Patent Publication Number: US-2022227343-A1

Title: Electronic brake system and operation method thereof

Description:
TECHNICAL FIELD 
     The present disclosure relates to an electronic brake system and an operation method thereof, and more particularly, to an electronic brake system and an operation method thereof for generating a braking force using an electrical signal corresponding to a displacement of a brake pedal. 
     BACKGROUND ART 
     In general, vehicles are essentially equipped with a brake system for performing braking, and various types of brake systems have been proposed for the safety of drivers and passengers. 
     In a conventional brake system, a method of supplying a hydraulic pressure required for braking to wheel cylinders using a mechanically connected booster when a driver depresses a brake pedal has been mainly used. However, as market demands to implement various braking functions in a detailed response to operation environments of vehicles increase, in recent years, an electronic brake system, that receives an electrical signal corresponding to a pressing force by a driver from a pedal displacement sensor that detects a displacement of a brake pedal when the driver depresses the brake pedal and operates a hydraulic pressure supply device based on the electric signal to supply a hydraulic pressure required for braking to wheel cylinders, have been widely used. 
     In such an electronic brake system, an electrical signal is generated and provided when a driver depresses the brake pedal in a normal operation mode, and based on the electric signal, the hydraulic pressure supply device is electrically operated and controlled to generate a hydraulic pressure required for braking and transfer the hydraulic pressure to the wheel cylinders. As such, although such an electronic brake system and an operation method are electrically operated and controlled so that complex and various braking operations may be implemented, when a technical problem occurs in an electric component, a hydraulic pressure required for braking may not be stably generated, and thus the safety of passengers may not be secured. 
     Therefore, the electronic brake system enters an abnormal operation mode when a component fails or becomes out of control, and in this case, a mechanism is required in which the operation of the brake pedal by a driver is directly linked to the wheel cylinders. That is, in the abnormal operation mode in the electronic brake system, as the driver depresses the brake pedal, a hydraulic pressure required for braking needs to be generated immediately and transferred directly to the wheel cylinders. 
     DISCLOSURE 
     Technical Problem 
     The present disclosure is directed to providing an electronic brake system capable of reducing the number of parts to be applied and achieving a miniaturization and lightweight of a product. 
     The present disclosure is directed to providing an electronic brake system capable of effectively implementing braking in various operating situations. 
     The present disclosure is directed to providing an electronic brake system capable of stably generating a braking pressure of a high pressure. 
     The present disclosure is directed to providing an electronic brake system capable of improving performance and operational reliability. 
     The present disclosure is directed to providing an electronic brake system capable of improving durability of a product by reducing loads applied to components. 
     The present disclosure is directed to providing an electronic brake system capable of improving easiness of assembly and productivity of a product and reducing a manufacturing cost of the product. 
     Technical Solution 
     An aspect of the present disclosure provides an electronic brake system including a reservoir in which a pressurized medium is stored, an integrated master cylinder including a master chamber, a master piston provided in the master chamber to be displaceable by a brake pedal, a first simulation chamber, a first simulation piston provided in the first simulation chamber to be displaceable by a displacement of the master piston or a hydraulic pressure of the pressurized medium accommodated in the master chamber, a second simulation chamber, a second simulation piston provided in the second simulation chamber to be displaceable by a displacement of the first simulation piston or a hydraulic pressure in the first simulation chamber, and an elastic member provided between the first simulation piston and the second simulation piston, a hydraulic pressure supply device provided to generate a hydraulic pressure by operating the hydraulic piston according to an electrical signal output in response to a displacement of the brake pedal, a hydraulic control unit including a first hydraulic circuit provided to control the hydraulic pressure transferred to two wheel cylinders and a second hydraulic circuit provided to control the hydraulic pressure transferred to the other two wheel cylinders, and an electronic control unit provided to control valves based on hydraulic pressure information and displacement information of the brake pedal. 
     The first hydraulic circuit may include a first inlet valve and a second inlet valve provided to control a flow of the pressurized medium to be supplied to a first wheel cylinder and a second wheel cylinder, respectively, a first outlet valve and a second outlet valve provided to control the flow of the pressurized medium to be discharged from the first wheel cylinder and the second wheel cylinder, respectively, and a discharge valve provided to control the flow of the pressurized medium to be supplied to the reservoir by passing through each of the first outlet valve and the second outlet valve, wherein the discharge valve may be provided as a solenoid valve that is linearly controlled to adjust a flow rate of the pressurized medium. 
     The integrated master cylinder may further include a simulation flow path connecting the first simulation chamber and the reservoir, and a simulator valve provided in the simulation flow path to control a flow of the pressurized medium. 
     The electronic brake system may include a first backup flow path connecting the master chamber and the first hydraulic circuit, a second backup flow path connecting the first simulation chamber and the second hydraulic circuit, a first cut valve provided in the first backup flow path to control the flow of the pressurized medium, at least one second cut valve provided in the second backup flow path to control the flow of the pressurized medium, an auxiliary backup flow path connecting the second simulation chamber and the second backup flow path, and an inspection valve provided in the auxiliary backup flow path to control the flow of the pressurized medium. 
     The hydraulic pressure supply device may include a first pressure chamber provided on one side of the hydraulic piston movably accommodated in the cylinder block to be connected to one or more of the wheel cylinders, and a second pressure chamber provided on the other side of the hydraulic piston to be connected to one or more of the wheel cylinders, and the hydraulic control unit may include a first hydraulic flow path in communication with the first pressure chamber, a second hydraulic flow path in communication with the second pressure chamber, a third hydraulic flow path in which the first hydraulic flow path and the second hydraulic flow path join, a fourth hydraulic flow path branched from the third hydraulic flow path to be connected to the first hydraulic circuit, and a fifth hydraulic flow path branched from the third hydraulic flow path to be connected to the second hydraulic circuit. 
     The hydraulic control unit may include a first valve provided in the first hydraulic flow path to control the flow of the pressurized medium, a second valve provided in the second hydraulic flow path to control the flow of the pressurized medium, a third valve provided in the fourth hydraulic flow path to control the flow of the pressurized medium, and a fourth valve provided in the fifth hydraulic flow path to control the flow of the pressurized medium. 
     The first valve may be provided as a check valve allowing only the flow of the pressurized medium discharged from the first pressure chamber, the second valve may be provided as a solenoid valve controlling the flow of the pressurized medium in bidirectional directions, the third valve may be provided as a check valve allowing only the flow of the pressurized medium directing to the first hydraulic circuit from the third hydraulic flow path, and the fourth valve may be provided as a check valve allowing only the flow of the pressurized medium directing to the second hydraulic circuit from the third hydraulic flow path. 
     The second hydraulic circuit may include a third inlet valve and a fourth inlet valve provided to control the flow of the pressurized medium to be supplied to third wheel cylinder and fourth wheel cylinder, respectively, and the second backup flow path may be provided to connect at least one of downstream sides of the third and fourth inlet valves to the first simulation chamber. 
     The first valve may be provided as a check valve allowing only the flow of the pressurized medium discharged from the first pressure chamber, the second valve and the fourth valve may be provided as solenoid valves controlling the flow of the pressurized medium in bidirectional directions, and the third valve may be provided as a check valve allowing only the flow of the pressurized medium directing to the first hydraulic circuit from the third hydraulic flow path. 
     The electronic brake system may further include generators provided in third wheel cylinder and fourth wheel cylinder in the second hydraulic circuit, respectively. 
     The hydraulic control unit may further include a sixth hydraulic flow path connecting the first hydraulic flow path and the second hydraulic flow path, and a fifth valve provided in the sixth hydraulic flow path to control the flow of the pressurized medium. 
     The first valve may be provided as a check valve allowing only the flow of the pressurized medium discharged from the first pressure chamber, the second valve may be provided as a check valve allowing only the flow of the pressurized medium discharged from the second pressure chamber, the third valve may be provided as a check valve allowing only the flow of the pressurized medium directing to the first hydraulic circuit from the third hydraulic flow path, the fourth valve may be provided as a check valve allowing only the flow of the pressurized medium directing to the second hydraulic circuit from the third hydraulic flow path, and the fifth valve may be provided as a solenoid valve controlling the flow of the pressurized medium in bidirectional directions. 
     In a normal operation mode, the first cut valve may be closed to seal the master chamber, the inspection valve may be closed to seal the second simulation chamber, and the second cut valve may be closed but the simulator valve may be opened to communicate the first simulation chamber and the reservoir, so that the first simulation piston may compress the elastic member by an operation of the brake pedal, and an elastic restoring force of the elastic member may be provided to a driver as a pedal feeling. 
     The normal operation mode, as the hydraulic pressure transferred from the hydraulic pressure supply device to the wheel cylinders increases, may include a first braking mode in which the hydraulic pressure is firstly provided by a forward movement of the hydraulic piston, a second braking mode in which the hydraulic pressure is secondarily provided by a backward movement of the hydraulic piston after the first braking mode, and a third braking mode in which the hydraulic pressure is thirdly provided by the forward movement of the hydraulic piston after the second braking mode. 
     In the first braking mode, the second valve may be closed, so that the hydraulic pressure generated in the first pressure chamber by the forward movement of the hydraulic piston may be provided to the first hydraulic circuit by sequentially passing through the first hydraulic flow path, the third hydraulic flow path, and the fourth hydraulic flow path, and provided to the second hydraulic circuit by sequentially passing through the first hydraulic flow path, the third hydraulic flow path, and the fifth hydraulic flow path. 
     In the second braking mode, the second valve may be opened, so that the hydraulic pressure generated in the second pressure chamber by the backward movement of the hydraulic piston after the first braking mode may be provided to the first hydraulic circuit by sequentially passing through the second hydraulic flow path, the third hydraulic flow path, and the fourth hydraulic flow path, and provided to the second hydraulic circuit by sequentially passing through the second hydraulic flow path, the third hydraulic flow path, and the fifth hydraulic flow path. 
     In the third braking mode, the second valve may be opened, so that a part of the hydraulic pressure generated in the first pressure chamber by the forward movement of the hydraulic piston after the second braking mode may be provided to the first hydraulic circuit by sequentially passing through the first hydraulic flow path, the third hydraulic flow path, and the fourth hydraulic flow path, and provided to the second hydraulic circuit by sequentially passing through the first hydraulic flow path, the third hydraulic flow path, and the fifth hydraulic flow path, and the remaining part of the hydraulic pressure generated in the first pressure chamber may be provided to the second pressure chamber by sequentially passing through the first hydraulic flow path and the second hydraulic flow path. 
     The first hydraulic circuit may further include a discharge valve provided to control the flow of the pressurized medium to be discharged from the two wheel cylinders to the reservoir, the discharge valve being linearly controlled to adjust a flow rate of the pressurized medium, wherein the second cut valve or the simulator valve may be provided as a solenoid valve that is linearly controlled to adjust the flow rate of the pressurized medium, and wherein when the first to third braking modes are released, a degree of opening of the discharge valve may be controlled, so that the pressurized medium provided to the first hydraulic circuit may be recovered to the reservoir through the discharge valve, and a degree of opening of the second cut valve or the simulator valve may be controlled, so that the pressurized medium provided to the second hydraulic circuit may be recovered to the reservoir by sequentially passing through the first simulation chamber and the simulation flow path. 
     In the regenerative braking mode by the generator, the fourth valve may be closed, so that the supply of hydraulic pressure from the hydraulic pressure supply device to the third wheel cylinder and the fourth wheel cylinder may be blocked. 
     The normal operation mode, as the hydraulic pressure transferred from the hydraulic pressure supply device to the wheel cylinders increases, may include a first braking mode in which the hydraulic pressure is firstly provided by a forward movement of the hydraulic piston, a second braking mode in which the hydraulic pressure is secondarily provided by a backward movement of the hydraulic piston after the first braking mode, and a third braking mode in which the hydraulic pressure is thirdly provided by the forward movement of the hydraulic piston after the second braking mode, wherein in the third braking mode, the fifth valve may be opened, so that a part of the hydraulic pressure generated in the first pressure chamber by the forward movement of the hydraulic piston after the second braking mode may be provided to the first hydraulic circuit by sequentially passing through the first hydraulic flow path, the third hydraulic flow path, and the fourth hydraulic flow path, and provided to the second hydraulic circuit by sequentially passing through the first hydraulic flow path, the third hydraulic flow path, and the fifth hydraulic flow path, and the remaining part of the hydraulic pressure generated in the first pressure chamber may be provided to the second pressure chamber by sequentially passing through the first hydraulic flow path, the sixth hydraulic flow path, and the second hydraulic flow path. 
     Advantageous Effects 
     An electronic brake system according to the present embodiment can reduce the number of parts to be applied and achieve a miniaturization and lightweight of a product. 
     The electronic brake system according to the present embodiment can stably and effectively implement braking in various operating situations of a vehicle. 
     The electronic brake system according to the present embodiment can stably generate a braking pressure of a high pressure. 
     The electronic brake system according to the present embodiment can improve performance and operational reliability of the product. 
     The electronic brake system according to the present embodiment can stably provide a braking pressure even when a device fails or a pressurized medium leaks. 
     The electronic brake system according to the present embodiment can improve durability of the product by reducing loads applied to components. 
     The electronic brake system according to the present embodiment can improve easiness of assembly and productivity of the product and reduce a manufacturing cost of the product. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a hydraulic circuit diagram illustrating an electronic brake system according to a first embodiment of the present disclosure. 
         FIG. 2  is a hydraulic circuit diagram illustrating that the electronic brake system according to the first embodiment of the present disclosure performs a first braking mode. 
         FIG. 3  is a hydraulic circuit diagram illustrating that the electronic brake system according to the first embodiment of the present disclosure performs a second braking mode. 
         FIG. 4  is a hydraulic circuit diagram illustrating that the electronic brake system according to the first embodiment of the present disclosure performs a third braking mode. 
         FIG. 5  is a hydraulic circuit diagram illustrating that the electronic brake system according to the first embodiment of the present disclosure releases a braking mode. 
         FIG. 6  is a hydraulic circuit diagram illustrating that the electronic brake system according to the first embodiment of the present disclosure performs an abnormal operation mode (fallback mode). 
         FIG. 7  is a hydraulic circuit diagram illustrating that the electronic brake system according to the first embodiment of the present disclosure performs an inspection mode. 
         FIG. 8  is a hydraulic circuit diagram illustrating an electronic brake system according to a second embodiment of the present disclosure. 
         FIG. 9  is a hydraulic circuit diagram illustrating that the electronic brake system according to the second embodiment of the present disclosure performs a regenerative braking mode. 
         FIG. 10  is a hydraulic circuit diagram illustrating an electronic brake system according to a third embodiment of the present disclosure. 
         FIG. 11  is a hydraulic circuit diagram illustrating that the electronic brake system according to the third embodiment of the present disclosure performs a first braking mode. 
         FIG. 12  is a hydraulic circuit diagram illustrating that the electronic brake system according to the third embodiment of the present disclosure performs a second braking mode. 
         FIG. 13  is a hydraulic circuit diagram illustrating that the electronic brake system according to the third embodiment of the present disclosure performs a third braking mode. 
         FIG. 14  is a hydraulic circuit diagram illustrating an electronic brake system according to a fourth embodiment of the present disclosure. 
     
    
    
     MODE OF THE DISCLOSURE 
     Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. The following embodiment is provided to fully convey the spirit of the present disclosure to a person having ordinary skill in the art to which the present disclosure belongs. The present disclosure is not limited to the embodiment shown herein but may be embodied in other forms. The drawings are not intended to limit the scope of the present disclosure in any way, and the size of components may be exaggerated for clarity of illustration. 
       FIG. 1  is a hydraulic circuit diagram illustrating an electronic brake system  1000  according to a first embodiment of the present disclosure. 
     Referring to  FIG. 1 , the electronic brake system  1000  according to the first embodiment of the present disclosure includes a reservoir  1100  in which a pressurized medium is stored, an integrated master cylinder  1200  provided to provide a reaction force against pressing of a brake pedal  10  to a driver and pressurize and discharge the pressurized medium such as brake oil accommodated therein, a hydraulic pressure supply device  1300  provided to receive an electrical signal corresponding to a pressing force by a driver from a pedal displacementsensor  11  that detects a displacement of the brake pedal  10  and to generate a hydraulic pressure of the pressurized medium through a mechanical operation, a hydraulic control unit  1400  provided to control the hydraulic pressure provided from the hydraulic pressure supply device  1300 , hydraulic circuits  1510  and  1520  having wheel cylinders  20  for braking respective wheels RR, RL, FR, and FL as the hydraulic pressure of the pressurized medium is transferred, a dump controller  1800  provided between the hydraulic pressure supply device  1300  and the reservoir  1100  to control a flow of the pressurized medium, backup flow paths  1610  and  1620  are provided to hydraulically connect the integrated master cylinder  1200  and the hydraulic circuits  1510  and  1520 , a reservoir flow path  1700  provided to hydraulically connect the reservoir  1100  and the integrated master cylinder  1200 , and an electronic control unit (ECU, not shown) provided to control the hydraulic pressure supply device  1300  and various valves based on hydraulic pressure inform ation. and pedal displacement information. 
     The integrated master cylinder  1200  includes simulation chambers  1230   a  and  1240   a,  and a master chamber  1220   a  to, when the driver presses the brake pedal  10  for braking operation, provide a reaction force against the pressing to the driver to provide a stable pedal feel, and at the same time pressurize and discharge the pressurized medium accommodated therein. 
     The integrated master cylinder  1200  may be divided into a pedal simulation part to provide a pedal feel to the driver, and a master cylinder part to transfer the pressurized medium to the first hydraulic circuit  1510  side, which will be described later. The integrated master cylinder  1200  may be configured such that the master cylinder part and the pedal simulation part are sequentially provided from the brake pedal  10  side and disposed coaxially within a cylinder block  1210 . 
     Specifically, the integrated master cylinder  1200  may include the cylinder block  1210  having a chamber formed therein, the master chamber  1220   a  formed on an inlet side of the cylinder block  1210  to which the brake pedal  10  is connected, a master piston  1220  provided in the master chamber  1220   a  and connected to the brake pedal  10  to be displaceable depending on the operation of the brake pedal  10 , a piston spring  1220   b  provided to elastically support the master piston  1220 , the first simulation chamber  1230   a  formed more inside than the master chamber  1220   a  on the cylinder block  1210 , a first simulation piston  1230  provided in the first simulation chamber  1230   a  to be displaceable by a displacement of the master piston  1220  or a hydraulic pressure of the pressurized medium accommodated in the master chamber  1220   a,  the second simulation chamber  1240   a  formed more inside than the first simulation chamber  1230   a  on the cylinder block  1210 , a second simulation piston  1240  provided in the second simulation chamber  1240   a  to be displaceable by a displacement of the first simulation chamber  1230   a  or a hydraulic pressure of the pressurized medium accommodated in the first simulation chamber  1230   a,  an elastic member  1250  disposed between the first simulation piston  1230  and the second simulation piston  1240  to provide a pedal feeling through an elastic restoring force generated during compression, a simulator spring  1270  provided to elastically support the second simulation piston  1240 , a simulation flow path  1260  provided to connect the first simulation chamber  1230   a  and the reservoir  1100 , and a simulator valve  1261  provided in the simulation flow path  1260  to control the flow of the pressurized medium. 
     The master chamber  1220   a,  the first simulation chamber  1230   a,  and the second simulation chamber  1240   a  may be sequentially formed toward the inside (left side of  FIG. 1 ) from the brake pedal  10  side (right side of  FIG. 1 ) on the cylinder block  1210  of the integrated master cylinder  1200 . Also, the master piston  1220 , the first simulation piston  1230 , and the second simulation piston  1240  are disposed in the master chamber  1220   a,  the first simulation chamber  1230   a,  and the second simulation chamber  1240   a,  respectively, to generate a hydraulic pressure or a negative pressure by the pressurized medium accommodated in the respective chambers depending on forward or backward movement. 
     The master chamber  1220   a  may be formed on the inlet side or the outermost side (right side of  FIG. 1 ) of the cylinder block  1210 , and the master piston  1220  connected to the brake pedal  10  via an input rod  12  may be accommodated in the master chamber  1220   a  to enable reciprocating movement. 
     The pressurized medium may be introduced into and discharged from the master chamber  1220   a  through a first hydraulic port  1280   a  and a second hydraulic port  1280   b.  The first hydraulic port  1280   a  is connected to a first reservoir flow path  1710 , which will be described later, so that the pressurized medium may be introduced into the master chamber  1220   a  from the reservoir  1100 , and the second hydraulic port  1280   b  is connected to a first backup flow path  1610 , which will be described later, so that the pressurized medium may be discharged into the first backup flow path  1610  side from the master chamber  1220   a,  or conversely, the pressurized medium may be introduced into the master chamber  1220   a  side from the first backup flow path  1610 . A pair of sealing members  1290   a  are provided in front and rear of the first hydraulic port  1280   a  to prevent leakage of the pressurized medium. The pair of sealing members  1290   a  may allow the flow of the pressurized medium directing to the first master chamber  1220   a  from the reservoir  1100  through the first reservoir flow path  1710  while blocking the flow of the pressurized medium directing to the first reservoir flow path  1710  from the first master chamber  1220   a.    
     The master piston  1220  may be accommodated in the master chamber  1220 a to generate a hydraulic pressure by pressurizing the pressurized medium accommodated in the master chamber  1220   a  by moving forward (left direction of  FIG. 1 ) or to generate a negative pressure inside the master chamber  1220   a  by moving backward (right direction of  FIG. 1 ). The master piston  1220  may be elastically supported by the piston spring  1220   b,  and the piston spring  1220   b  may be provided with one end supported by the cylinder block  1210  and the other end supported by a flange portion formed by extending outwardly from an end of the master piston  1220 . 
     The first simulation chamber  1230   a  may be formed at an inner side (left side of  FIG. 1 ) of the master chamber  1220   a  on the cylinder block  1210 , and the first simulation piston  1230  may be accommodated in the first simulation chamber  1230   a  to enable reciprocating movement. 
     The pressurized medium may be introduced into and discharged from the first simulation chamber  1230   a  through a third hydraulic port  1280   c  and a fourth hydraulic port  1280   d.  The third hydraulic port  1280   c  is connected to a second reservoir flow path  1720  and the simulation flow path  1260 , which will be described later, so that the pressurized medium accommodated in the first simulation chamber  1230   a  may be discharged into the reservoir  1100  side, or conversely, the pressurized medium may be introduced from the reservoir  1100 . The fourth hydraulic port  1280   d  is connected to the second backup flow path  1620 , which will be described later, so that the pressurized medium accommodated in the first simulation chamber  1230   a  may be discharged into the second hydraulic circuit  1520  side, or conversely, the pressurized medium may be introduced into the first simulation chamber  1230   a  side from the second backup flow path  1620 . 
     The first simulation piston  1230  may be accommodated in the first simulation chamber  1230   a  to generate a hydraulic pressure of the pressurized medium accommodated in the first simulation chamber  1230   a  or press the elastic member  1250 , which will be described later, by moving forward, or to generate a negative pressure inside the first simulation chamber  1230   a  or return the elastic member  1250  to an original position and shape thereof by moving backward. At least one sealing member  1290   b  may be provided between an inner wall of the cylinder block  1210  and an outer circumferential surface of the first simulation piston  1230  to prevent leakage of the pressurized medium between the adjacent chambers. 
     A step portion formed to be stepped may be provided at a portion where the first simulation chamber  1230   a  is formed on the cylinder block  1210 , and an extension portion provided to be caught on the step portion by expanding outwardly may be provided on the outer circumferential surface of the first simulation piston  1230 . As the extension portion of the first simulation piston  1230  is provided to be caught on the step portion of the cylinder block  1210 , in order for the first simulation piston  1230  to return to an original position thereof after moving forward by the operation of the brake pedal  10 , a backward stroke degree of the first simulation piston  1230  when moving backward may be limited. 
     The second simulation chamber  1240   a  may be formed at an inner side (left side of  FIG. 1 ) of the first simulation chamber  1230   a  on the cylinder block  1210 , and the second simulation piston  1240  may be accommodated in the second simulation chamber  1240   a  to enable reciprocating movement. 
     The pressurized medium may be introduced into and discharged from the second simulation chamber  1240   a  through a fifth hydraulic port  1280   e  and a sixth hydraulic port  1280 f. Specifically, the fifth hydraulic port  1280   e  is connected to a third reservoir flow path  1730 , which will be described later, so that the pressurized medium may be introduced into the second simulation chamber  1240   a  side from the reservoir  1100  or discharged from the second simulation chamber  1240  to the reservoir  1100  side. The sixth hydraulic port  1280 f is connected to an auxiliary backup flow path  1630 , which will be described later, so that the pressurized medium accommodated in the second simulation chamber  1240   a  may be discharged into the second backup flow path  1620  side, or conversely, the pressurized medium may be introduced into the second simulation chamber  1240   a  side from the second backup flow path  1620  side. 
     The second simulation piston  1240  may be accommodated in the second simulation chamber  1240   a  to generate a hydraulic pressure of the pressurized medium accommodated in the second simulation chamber  1240   a  by moving forward, or to generate a negative pressure inside the second simulation chamber  1240   a  by moving backward. At least one sealing member  1290   c  may be provided between the inner wall of the cylinder block  1210  and an outer circumferential surface of the second simulation piston  1240  to prevent leakage of the pressurized medium between the adjacent chambers. The sealing member  1290   c  may allow the flow of the pressurized medium directing to the second simulation chamber  1240   a  from the reservoir  1100  through the third reservoir flow path  1730  while blocking the flow of the pressurized medium directing to the third reservoir flow path  1730  from the second simulation chamber  1240   a.    
     The integrated master cylinder  1200  according to the present embodiment may secure safety in the event of a failure of a device by including the master chamber  1220   a  and the simulation chambers  1230   a  and  1240   a.  For example, the master chamber  1220   a  may be connected to the wheel cylinders  20  of any two of a right front wheel FR, a left front wheel FL, a left rear wheel RL, and a right rear wheel RR through the first backup flow path  1610 , which will be described later, and the simulation chambers  1230   a  and  1240   a  may be connected to the wheel cylinders  20  of the other two through the second backup flow path  1620  and the auxiliary backup flow path  1630 , which will be described later, and thus even when a problem such as a leak in any one of the chambers occurs, it may be possible to brake the vehicle. A detailed description thereof will be given later with reference to  FIG. 6 . 
     The elastic member  1250  is interposed between the first simulation piston  1230  and the second simulation piston  1240  to provide a pedal feeling of the brake pedal  10  to the driver by its own elastic restoring force. The elastic member  1250  may be made of a material such as compressible and expandable rubber, and when a displacement occurs in the first simulation piston  1230  by the operation of the brake pedal  10 , but when the second simulation piston  1240  is maintained in an original position thereof, the elastic member  1250  is compressed, and the driver may receive a stable and familiar pedal feeling by the elastic restoring force of the compressed elastic member  1250 . A detailed description thereof will be given later. 
     Accommodating grooves recessed in a shape corresponding to the shape of the elastic member  1250  to facilitate smooth compression and deformation of the elastic member  1250  may be provided on a rear surface (left surface of  FIG. 1 ) of the first simulation piston  1230  and a front surface (right surface of  FIG. 1 ) of the second simulation piston  1240 , which face the elastic member  1250 , respectively. 
     The simulator spring  1270  is provided to elastically support the second simulation piston  1240 . The simulator spring  1270  has one end supported by the cylinder block  1210  and the other end supported by the second simulation piston  1240 , thereby resiliently supporting the second simulation piston  1240 . When the second simulation piston  1240  moves forward according to a braking operation to generate a displacement, the simulator spring  1270  is compressed, and thereafter, when the braking is released, as the simulator spring  1270  expands by an elastic force thereof, the second simulation piston  1240  may return to the original position. 
     The simulation flow path  1260  is provided such that the first simulation chamber  1230   a  and the reservoir  1100  are in communication with each other, and the simulator valve  1261  for controlling bidirectional flows of the pressurized medium may be provided in the simulation flow path  1260 . The simulator valve  1261  may be provided as a normally closed type solenoid valve that operates to be opened when an electric signal is received from the electronic control unit in a normally closed state. The simulator valve  1261  may be opened in a normal operation mode of the electronic brake system  1000 . 
     Explaining a pedal simulation operation by the integrated master cylinder  1200 , at the same time as the driver operates the brake pedal  10  in a normal operation, a first cut valve  1611  and a second cut valve  1621  provided in the first backup flow path  1610  and the second backup flow path  1620 , which will be described later, respectively, are closed, while the simulator valve  1261  in the simulation flow path  1260  is opened. As the operation of the brake pedal  10  progresses, the master piston  1220  moves forward, but the master chamber  1220   a  is sealed by a closing operation of the first cut valve  1611 , so that as the hydraulic pressure of the pressurized medium accommodated in the master chamber  1220   a  is transferred to the first simulation piston  1230 , the first simulation piston  1230  moves forward to generate a displacement. On the other hand, as the second cut valve  1621  is closed, the second simulation chamber  1240   a  is sealed so that a displacement of the second simulation piston  1240  is not generated, and thus the elastic member  1250  is compressed by the displacement of the first simulation piston  1230 , and the elastic restoring force by compression of the elastic member  1250  may be provided to the driver as the pedal feeling. At this time, the pressurized medium accommodated in the first simulation chamber  1230   a  is transferred to the reservoir  1100  through the simulation flow path  1260 . Thereafter, when the driver releases the pressing force of the brake pedal  10 , the piston spring  1220   b  and the elastic member  1250  return to the original shape and position thereof by the elastic restoring force, and the first simulation chamber  1230   a  may be filled with the pressurized medium supplied from the reservoir  1100  through the simulation flow path  1260 . 
     As such, because the insides of the first simulation chamber  1230   a  and the second simulation chamber  1240   a  are always filled with the pressurized medium, when the pedal simulation is operated, friction of the first simulation piston  1230  and the second simulation piston  1240  is minimized, so that the durability of the integrated master cylinder  1200  is improved and at the same time the inflow of foreign substances from the outside may be blocked. 
     A case in which the electronic brake system  1000  operates abnormally, that is, an operation of the integrated master cylinder  1200  in a fallback mode will be described later with reference to  FIG. 6 . 
     The reservoir  1100  may accommodate and store the pressurized medium therein. The reservoir  1100  may be connected to each component such as the integrated master cylinder  1200 , the hydraulic pressure supply device  1300 , which will be described later, and the hydraulic circuits, which will be described later, to supply or receive the pressurized medium. Although a plurality of the reservoirs  1100  is shown with the same reference numeral in the drawings, this is only an example for better understanding of the present disclosure, and the reservoir  1100  may be provided as a single component, or a plurality of the separate and independent reservoirs  1100  may be provided. 
     The reservoir flow path  1700  is provided to connect the integrated master cylinder  1200  and the reservoir  1100 . 
     The reservoir flow path  1700  may include the first reservoir flow path  1710  connecting the master chamber  1220   a  and the reservoir  1100 , the second reservoir flow path  1720  connecting the first simulation chamber  1230   a  and the reservoir  1100 , and the third reservoir flow path  1730  connecting the second simulation chamber  1240   a  and the reservoir  1100 . To this end, one end of the first reservoir flow path  1710  may communicate with the master chamber  1220   a  of the integrated master cylinder  1200  and the other end thereof may communicate with the reservoir  1100 , one end of the second reservoir flow path  1720  may communicate with the first simulation chamber  1230   a  of the integrated master cylinder  1200  and the other end thereof may communicate with the reservoir  1100 , and one end of the third reservoir flow path  1730  may communicate with the second simulation chamber  1240   a  of the integrated master cylinder  1200  and the other end thereof may communicate with the reservoir  1100 . As shown in the drawing, the second reservoir flow path  1720  may be connected to the reservoir  1100  as the simulation flow path  1260  is branched from the second reservoir flow path  1720  and rejoins the second reservoir flow path  1720 , but is not limited thereto, and the second reservoir flow path  1720  and the simulation flow path  1260  may be connected to the reservoir  1100  independently of each other. 
     A reservoir valve  1721  for controlling a flow of a braking fluid transferred through the second reservoir flow path  1720  may be provided in the second reservoir flow path  1720 . The reservoir valve  1721  may be provided as a check valve allowing the flow of the pressurized medium directing to the first simulation chamber  1230 a from the reservoir  1100  while blocking the flow of the pressurized medium directing to the reservoir  1100  from the first simulation chamber  1230   a.    
     The hydraulic pressure supply device  1300  is provided to receive an electrical signal corresponding to a pressing force of the driver from the pedal displacement sensor  11  detecting a displacement of the brake pedal  10  and to generate a hydraulic pressure of the pressurized medium through a mechanical operation. 
     The hydraulic pressure supply device  1300  may include a hydraulic pressure providing unit to provide a pressure to the pressurized medium to be transferred to the wheel cylinders  20 , a motor (not shown) to generate a rotational force by an electrical signal from the pedal displacement sensor  11 , and a power conversion unit (not shown) to convert a rotational motion of the motor into a linear motion to provide the linear motion to the hydraulic pressure providing unit. 
     The hydraulic pressure providing unit includes a cylinder block  1310  provided such that the pressurized medium may be accommodated, a hydraulic piston  1320  accommodated in the cylinder block  1310 , a sealing member  1350  provided between the hydraulic piston  1320  and the cylinder block  1310  to seal the pressure chambers  1330  and  1340 , and a drive shaft  1390  to transfer power output from the power conversion unit to the hydraulic piston  1320 . 
     The pressure chambers  1330  and  1340  may include the first pressure chamber  1330  located in the front of the hydraulic piston  1320  (left direction of the hydraulic piston  1320  in  FIG. 1 ), and the second pressure chamber  1340  located in the rear of the hydraulic piston  1320  (right direction of the hydraulic piston  1320  in  FIG. 1 ). That is, the first pressure chamber  1330  is provided to be partitioned by the cylinder block  1310  and a front surface of the hydraulic piston  1320  so that a volume thereof varies depending on the movement of the hydraulic piston  1320 , and the second pressure chamber  1340  is provided to be partitioned by the cylinder block  1310  and a rear surface of the hydraulic piston  1320  so that a volume thereof varies depending on the movement of the hydraulic piston  1320 . 
     The first pressure chamber  1330  is connected to a first hydraulic flow path  1401 , which will be described later, through a first communication hole  1360   a  formed on the cylinder block  1310 , and the second pressure chamber  1340  is connected to a second hydraulic flow path  1402 , which will be described later, through a second communication hole  1360   b  formed on the cylinder block  1310 . 
     The sealing members include a piston sealing member  1350   a  provided between the hydraulic piston  1320  and the cylinder block  1310  to seal between the first pressure chamber  1330  and the second pressure chamber  1340 , and a drive shaft sealing member  1350   b  provided between the drive shaft  1390  and the cylinder block  1310  to seal between the second pressure chamber  1340  and an opening of the cylinder block  1310 . The hydraulic pressure or negative pressure of the first pressure chamber  1330  and the second pressure chamber  1340  generated by the forward or backward movement of the hydraulic piston  1320  may not leak by being sealed by the piston sealing member  1350   a  and the drive shaft sealing member  1350   b  and may be transferred to the first hydraulic flow path  1401  and the second hydraulic flow path  1402 , which will be described later. 
     The motor (not shown) is provided to generate a driving force of the hydraulic piston  1320  by an electric signal output from the electronic control unit. The motor may include a stator and a rotor, and through this configuration, may provide power to generate a displacement of the hydraulic piston  1320  by rotating in a forward or reverse direction. A rotational angular speed and a rotational angle of the motor may be precisely controlled by a motor control sensor. Because the motor is a well-known technology, a detailed description thereof will be omitted. 
     The power conversion unit (not shown) is provided to convert a rotational force of the motor into a linear motion. The power conversion unit may be provided as a structure including, for example, a worm shaft (not shown), a worm wheel (not shown), and the drive shaft  1390 . 
     The worm shaft may be integrally formed with a rotation shaft of the motor and may rotate the worm wheel by a worm formed on an outer circumferential surface thereof to be engaged with the worm wheel. The worm wheel may linearly move the drive shaft  1390  by being connected to be engaged with the drive shaft  1390 , and the drive shaft  1390  is connected to the hydraulic piston  1320  so that the hydraulic piston  1320  may be slidably moved within the cylinder block  1310 . 
     Explaining the above operations again, when the displacement of the brake pedal  10  is detected by the pedal displacement sensor  11 , the detected signal is transferred to the electronic control unit, and the electronic control unit drives the motor to rotate the worm shaft in one direction. The rotational force of the worm shaft is transferred to the drive shaft  1390  via the worm wheel, and the hydraulic piston  1320  connected to the drive shaft  1390  moves forward in the cylinder block  1310 , thereby generating a hydraulic pressure in the first pressure chamber  1330 . 
     Conversely, when the pressing force of the brake pedal  10  is released, the electronic control unit drives the motor to rotate the worm shaft in the opposite direction. Accordingly, the worm wheel also rotates in the opposite direction, and the hydraulic piston  1320  connected to the drive shaft  1390  moves backward in the cylinder block  1310 , thereby generating a negative pressure in the first pressure chamber  1330 . 
     The generation of a hydraulic pressure and negative pressure in the second pressure chamber  1340  may be implemented by operating opposite to the above operations. That is, when the displacement of the brake pedal  10  is detected by the pedal displacement sensor  11 , the detected signal is transferred to the electronic control unit, and the electronic control unit drives the motor to rotate the worm shaft in the opposite direction. The rotational force of the worm shaft is transferred to the drive shaft  1390  via the worm wheel, and the hydraulic piston  1320  connected to the drive shaft  1390  moves backward within the cylinder block  1310 , thereby generating a hydraulic pressure in the second pressure chamber  1340 . 
     Conversely, when the pressing force of the brake pedal  10  is released, the electronic control unit drives the motor to rotate the worm shaft in one direction. Accordingly, the worm wheel also rotates in one direction, and the hydraulic piston  1320  connected to the drive shaft  1390  moves forward in the cylinder block  1310 , thereby generating a negative pressure in the second pressure chamber  1340 . 
     As such, the hydraulic pressure supply device  1300  may generate a hydraulic pressure or negative pressure in the first pressure chamber  1330  and the second pressure chamber  1340 , respectively, depending on the rotation direction of the worm shaft by the operation of the motor, and whether a hydraulic pressure is transferred to the chambers to perform braking, or whether a negative pressure is generated in the chambers to release braking may be determined by controlling the valves. A detailed description thereof will be given later. 
     The power conversion unit according to the present embodiment is not limited to any one structure as long as it may convert the rotational motion of the motor into the linear motion of the hydraulic piston  1320 , and may include devices having various structures and manners. 
     The hydraulic pressure supply device  1300  may be hydraulically connected to the reservoir  1100  by the dump controller  1800 . The dump controller  1800  may include a first dump flow path  1810  connecting the first pressure chamber  1330  and the reservoir  1100 , and a second dump flow path  1820  connecting the second pressure chamber  1340  and the reservoir  1100 . 
     A first dump check valve  1811  and a second dump check valve  1821  for controlling the flow of the pressurized medium may be provided in the first dump flow path  1810  and the second dump flow path  1820 , respectively. The first dump check valve  1811  may be provided to allow only the flow of the pressurized medium directing to the first pressure chamber  1330  from the reservoir  1100  and block the flow of the pressurized medium in the opposite direction, and the second dump check valve  1821  may be provided to allow only the flow of the pressurized medium directing to the second pressure chamber  1340  from the reservoir  1100  and block the flow of the pressurized medium in the opposite direction. 
     The hydraulic control unit  1400  may be provided to control a hydraulic pressure transferred to the respective wheel cylinders  20 , and the electronic control unit (ECU) is provided to control the hydraulic pressure supply device  1300  and various valves based on the hydraulic pressure information and pedal displacement information. 
     The hydraulic control unit  1400  may include the first hydraulic circuit  1510  for controlling the flow of the hydraulic pressure to be transferred to first and second wheel cylinders  21  and  22  among the four wheel cylinders  20 , and the second hydraulic circuit  1520  for controlling the flow of the hydraulic pressure to be transferred to third and fourth wheel cylinders  23  and  24 , and includes a plurality of flow paths and valves to control the hydraulic pressure to be transferred from the hydraulic pressure supply device  1300  to the wheel cylinders  20 . 
     The first hydraulic flow path  1401  is provided to be in communication with the first pressure chamber  1330 , and the second hydraulic flow path  1402  is provided to be in communication with the second pressure chamber  1340 . The first hydraulic flow path  1401  and the second hydraulic flow path  1402  may be provided to join in a third hydraulic flow path  1403 , and then may be formed to be branched into a fifth hydraulic flow path  1405  and a sixth hydraulic flow path  1406  to be respectively connected to the first hydraulic circuit  1510  and the second hydraulic circuit  1520 . 
     A first valve  1411  for controlling the flow of the pressurized medium may be provided in the first hydraulic flow path  1401 . The first valve  1411  may be provided as a check valve allowing only the flow of the pressurized medium directing to the third hydraulic flow path  1403  from the first pressure chamber  1330  and blocking the flow of the pressurized medium in the opposite direction. A second valve  1412  for controlling the flow of the pressurized medium is provided in the second hydraulic flow path  1402 , and the second valve  1412  may be provided as a bidirectional control valve for controlling the flow of the pressurized medium transferred along the second hydraulic flow path  1402 . The second valve  1412  may be provided as a normally closed type solenoid valve that operates to be opened when an electric signal is received from the electronic control unit in a normally closed state. The second valve  1412  may be controlled to be opened in a second braking mode and a third braking mode in the normal operation mode of the electronic brake system  1000 . A detailed description thereof will be given later with reference to  FIGS. 3 and 4 . 
     The first hydraulic flow path  1401  and the second hydraulic flow path  1402  may be joined to form the third hydraulic flow path  1403 , and the third hydraulic flow path  1403  is formed to be branched into a fourth hydraulic flow path  1404  connected to the first hydraulic circuit  1510  and the fifth hydraulic flow path  1405  connected to the second hydraulic circuit  1520 . 
     A third valve  1413  for controlling the flow of the pressurized medium may be provided in the fourth hydraulic flow path  1404 . The third valve  1413  may be provided as a check valve allowing only the flow of the pressurized medium directing to the first hydraulic circuit  1510  from the third hydraulic flow path  1403  and blocking the flow of the pressurized medium in the opposite direction. A fourth valve  1414  for controlling the flow of the pressurized medium may be provided in the fifth hydraulic flow path  1405 , and the fourth valve  1414  may be provided as a check valve allowing only the flow of the pressurized medium directing to the second hydraulic circuit  1520  from the third hydraulic flow path  1403  and blocking the flow of the pressurized medium in the opposite direction. 
     By the arrangement of the hydraulic flow paths and valves of the hydraulic control unit  1400  as described above, the hydraulic pressure generated in the first pressure chamber  1330  according to the forward movement of the hydraulic piston  1320  may be transferred to the first hydraulic circuit  1510  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 , and may be transferred to the second hydraulic circuit  1520  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . Also, the hydraulic pressure formed in the second pressure chamber  1340  according to the backward movement of the hydraulic piston  1320  may be transferred to the first hydraulic circuit  1510  by sequentially passing through the second hydraulic flow path  1402 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 , and may be transferred to the second hydraulic circuit  1520  by sequentially passing through the second hydraulic flow path  1402 , the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . 
     Conversely, a negative pressure may be generated in the first pressure chamber  1330  according to the backward movement of the hydraulic piston  1320 , and thus the pressurized medium may be supplied from the reservoir  1100  to the first pressure chamber  1330  through the first dump flow path  1810 . Also, a negative pressure may be generated in the second pressure chamber  1340  according to the forward movement of the hydraulic piston  1320 , and thus the pressurized medium may be supplied from the reservoir  1100  to the second pressure chamber  1340  through the second dump flow path  1820 . 
     A detailed description of the transfer of the hydraulic pressure and negative pressure by the arrangement of these hydraulic flow paths and valves will be given later with reference to  FIGS. 2 to 5 . 
     The first hydraulic circuit  1510  of the hydraulic control unit  1400  may control the hydraulic pressure in the first wheel cylinder  21  and the second wheel cylinder  22 , which are the two wheel cylinders  20  among the four wheels RR, RL, FR, and FL, and the second hydraulic circuit  1520  may control the hydraulic pressure in the third and fourth wheel cylinders  23  and  24  which are the other two wheel cylinders  20 . 
     The first hydraulic circuit  1510  receives the hydraulic pressure through the fourth hydraulic flow path  1404 , and the fourth hydraulic flow path  1404  may be formed to be branched into two flow paths connected to the first wheel cylinder  21  and the second wheel cylinder  22 . Also, the second hydraulic circuit  1520  receives the hydraulic pressure through the fifth hydraulic flow path  1405 , and the fifth hydraulic flow path  1405  may be formed to be branched into two flow paths connected to the third wheel cylinder  23  and the fourth wheel cylinder  242 . 
     The first and second hydraulic circuits  1510  and  1520  may include first to fourth inlet valves  1511   a,    1511   b,    1521   a,  and  1521   b,  respectively, to control the flow and hydraulic pressure of the pressurized medium to be transferred to the first to fourth wheel cylinders  21  to  24 . The first to fourth inlet valves  1511   a,    1511   b,    1521   a,  and  1521   b  are disposed on upstream sides of the first to fourth wheel cylinders  20 , respectively, and may be provided as a normally open type solenoid valve that operates to be closed when an electric signal is received from the electronic control unit in a normally open state. 
     The first and second hydraulic circuits  1510  and  1520  may include first to fourth check valves  1513   a,    1513   b,    1523   a,  and  1523   b  provided to be connected in parallel with respect to the first to fourth inlet valves  1511   a,    1511   b,    1521   a,  and  1521   b.  The check valves  1513   a,    1513   b,    1523   a,  and  1523   b  may be provided in bypass flow paths connecting front sides and rear sides of the first to fourth inlet valves  1511   a,    1511   b,    1521   a,  and  1521   b  on the first and second hydraulic circuits  1510  and  1520 , and may allow only the flow of pressurized medium from each of the wheel cylinders  20  to the hydraulic pressure supply device  1300  while blocking the flow of the pressurized medium from the hydraulic pressure supply device  1300  to the wheel cylinders  20 . By the first to fourth check valves  1513   a,    1513   b,    1523   a,  and  1523   b,  the hydraulic pressure of the pressurized medium applied to each of the wheel cylinders  20  may be quickly released, and even when the first to fourth inlet valves  1511   a,    1511   b,    1521   a,  and  1521   b  do not operate normally, the hydraulic pressure of the pressurized medium applied to the wheel cylinders  20  may be smoothly returned to the hydraulic pressure providing unit. 
     The first hydraulic circuit  1510  may include first and second outlet valves  1512   a  and  1512   b  for controlling the flow of the pressurized medium discharged from the first and second wheel cylinders  21  and  22  to improve performance when braking of the first and second wheel cylinders  21  and  22  is released. The first and second outlet valves  1512   a  and  1512   b  are provided on discharge sides of the first and second wheel cylinders  21  and  22 , respectively, to control the flow of the pressurized medium transferred from the first and second wheel cylinders  21  and  22  to a discharge valve  1550 , which will be described late. The first and second outlet valves  1512   a  and  1512   b  may be provided as normally open type solenoid valves that operate to be closed when an electric signal is received from the electronic control unit in a normally open state. 
     The discharge valve  1550  is provided to control the flow of the pressurized medium recovered from the first and second outlet valves  1512   a  and  1512   b  to the reservoir  1100 . To this end, the discharge valve  1550  may be provided between the first and second outlet valves  1512   a  and  1512   b  and the reservoir  1100 , is provided as a normally closed type valve that operates to be opened when an electric signal is received from the electronic control unit in a normally closed state, and may be provided as a solenoid valve in which an opening degree thereof is linearly adjustable to control a flow rate of the pressurized medium discharged from the first and second outlet valves  1512   a  and  1512   b  to the reservoir  1100 . The discharge valve  1550  may discharge the hydraulic pressure of the pressurized medium applied to the first and second wheel cylinders  21  and  22  to the reservoir  1100  side by adjusting the opening degree in the normal operation mode of the electromagnetic brake system  1000 , thereby performing a pressure reduction braking or a braking release. A release of the braking modes of the electromagnetic brake system  1000  by the discharge valve  1550  will be described later with reference to  FIG. 5 . 
     The second backup flow path  1620 , which will be described later, may be branched and connected to the third and fourth wheel cylinders  23  and  24  of the second hydraulic circuit  1520 , and the second cut valve  1621  may be provided in the second backup flow path  1620  to control the flow of the pressurized medium between the third and fourth wheel cylinders  23  and  24  and the integrated master cylinder  1200 . 
     The electronic brake system  1000  according to the present embodiment may include the first and second backup flow paths  1610  and  1620  and the auxiliary backup flow path  1630  to implement braking by directly supplying the pressurized medium discharged from the integrated master cylinder  1200  to the wheel cylinders  20  when the normal operation is impossible due to a device failure or the like. A mode in which the hydraulic pressure in the integrated master cylinder  1200  is directly transferred to the wheel cylinders  20  is referred to as an abnormal operation mode, that is, a fallback mode. 
     The first backup flow path  1610  may be provided to connect the master chamber  1220   a  of the integrated master cylinder  1200  and the first hydraulic circuit  1510 , and the second backup flow path  1620  may be provided to connect the first simulation chamber  1230   a  of the integrated master cylinder  1200  and the second hydraulic circuit  1520 . The auxiliary backup flow path  1630  is provided to connect the second simulation chamber  1240   a  of the integrated master cylinder  1200  and the second backup flow path  1620 . 
     Specifically, the first backup flow path  1610  may have one end connected to the master chamber  1220   a  and the other end connected between the first inlet valve  1511   a  and the first outlet valve  1512   a  on the first hydraulic circuit  1510 , and the second backup flow path  1620  may have one end connected to the first simulation chamber  1230   a  and the other end connected to downstream sides of the third and fourth inlet valves  1521   a  and  1521   b  on the second hydraulic circuit  1520 . Although  FIG. 1  illustrates that the first backup flow path  1610  is connected between the first inlet valve  1511   a  and the first outlet valve  1512   a,  the first backup flow path  1610  may be branched and connected to at least one of upstream sides of the first outlet valve  1512   a  and the second outlet valve  1512   b.  The auxiliary backup flow path  1630  has one end connected to the second simulation chamber  1240   a  and the other end provided to join the second backup flow path  1620 , so that the pressurized medium accommodated in the second simulation chamber  1240   a  may be transferred to the second backup flow path  1620 . 
     The first cut valve  1611  for controlling the bidirectional flows of the pressurized medium may be provided in the first backup flow path  1610 , and the at least one second cut valve  1621  for controlling the bidirectional flows of the pressurized medium may be provided in the second backup flow path  1620 . The first cut valve  1611  and the second cut valve  1621  may be provided as normally open type solenoid valves that operate to be closed when a closing signal is received from the electronic control unit in a normally open state. 
     An inspection valve  1631  for controlling the bidirectional flows of the pressurized medium is provided in the auxiliary backup flow path  1630 , and the inspection valve  1631  may be provided as a normally open type solenoid valve that operates to be closed when a closing signal is received from the electronic control unit in a normally open state. The inspection valve  1631  may be closed in the normal operation of the electronic brake system  1000  to seal the second simulation chamber  1240   a,  and may be closed in an inspection mode of inspecting whether a leak occurs in the integrated master cylinder  1200  or the simulator valve  1261 . A detailed description thereof will be given later. 
     Accordingly, when the first and second cut valves  1621  are closed, the pressurized medium in the integrated master cylinder  1200  may be prevented from being directly transferred to the wheel cylinders  20 , and at the same time the hydraulic pressure provided from the hydraulic pressure supply device  1300  may be supplied to the first and second hydraulic circuits  1510  and  1520  side through the hydraulic control unit  1400 , and when the first and second cut valves  1611  and  1612  and inspection valve  1631  are opened, the pressurized medium pressurized in the integrated master cylinder  1200  may be directly supplied to the first and second hydraulic circuits  1510  and  1520  side through the first and second backup flow paths  1620  and the auxiliary backup flow path  1630 , thereby performing braking. 
     The electronic brake system  1000  according to the present embodiment may include a pressure sensor PS to detect a hydraulic pressure in at least one of the first hydraulic circuit  1510  and the second hydraulic circuit  1520 . The drawing illustrates that the pressure sensor PS is provided in the second hydraulic circuit  1520  side, but the pressure sensor is not limited to the above position and number, and as long as the hydraulic pressures in the hydraulic circuits and the integrated master cylinder  1200  may be detected, the pressure sensor may be provided in various positions and in various numbers. 
     Hereinafter, operation methods of the electronic brake system  1000  according to the first embodiment of the present disclosure will be described. 
     The operation of the electronic brake system  1000  according to the present embodiment may include the normal operation mode in which various devices and valves operate normally without failure or malfunction, the abnormal operation mode (fallback mode) in which various devices and valves operate abnormally due to failure or malfunction, and the inspection mode of inspecting whether a leak occurs in the integrated master cylinder  1200  or the simulation valve  1261 . 
     First, the normal operation mode among the operating methods of the electronic brake system  1000  according to the present embodiment will be described. 
     The normal operation mode of the electronic brake system  1000  according to the present embodiment may be classified into a first braking mode, a second braking mode, and a third braking mode as the hydraulic pressure transferred from the hydraulic pressure supply device  1300  to the wheel cylinders  20  increases. Specifically, in the first braking mode, the hydraulic pressure may be firstly provided to the wheel cylinders  20  by the hydraulic pressure supply device  1300 , in the second braking mode, the hydraulic pressure may be secondarily provided to the wheel cylinders  20  by the hydraulic pressure supply device  1300  to transfer a higher braking pressure than in the first braking mode, and in the third braking mode, the hydraulic pressure may be thirdly provided to the wheel cylinders  20  by the hydraulic pressure supply device  1300  to transfer a higher braking pressure than in the second braking mode. 
     The first to third braking modes may be changed by varying the operations of the hydraulic pressure supply device  1300  and the hydraulic control unit  1400 . The hydraulic pressure supply device  1300  may provide a sufficiently high hydraulic pressure of the pressurized medium without a high specification motor by utilizing the first to third braking modes, and furthermore, may prevent unnecessary loads applied to the motor. Therefore, a stable braking force may be secured while reducing the cost and weight of the brake system, and durability and operational reliability of the devices may be improved. 
       FIG. 2  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the present embodiment performs the first braking mode. 
     Referring to  FIG. 2 , when the driver depresses the brake pedal  10  at a beginning of braking, the motor (not shown) operates to rotate in one direction, the rotational force of the motor is transferred to the hydraulic pressure providing unit by the power conversion unit, and the hydraulic piston  1320  of the hydraulic pressure providing unit moves forward, thereby generating a hydraulic pressure in the first pressure chamber  1330 . The hydraulic pressure discharged from the first pressure chamber  1330  is transferred to the respective wheel cylinders  20  through the hydraulic control unit  1400 , the first hydraulic circuit  1510  and the second hydraulic circuit  1520 , thereby generating a braking force. 
     Specifically, the hydraulic pressure generated in the first pressure chamber  1330  is primarily transferred to the first wheel cylinder  21  and the second wheel cylinder  22  provided in the first hydraulic circuit  1510  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 . At this time, as the first valve  1411  and the third valve  1413  are provided as check valves allowing only the flow of the pressurized medium directing to the first hydraulic circuit  1510  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the first and second wheel cylinders  21  and  22 . Also, the first inlet valve  1511   a  and the second inlet valve  1511   b  provided in the first hydraulic circuit  1510  are maintained in an open state, and the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550  are controlled to be closed, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the reservoir  1100  side. 
     Also, the hydraulic pressure of the pressurized medium generated in the first pressure chamber  1330  is primarily transferred to the third and fourth wheel cylinders  23  and  24  provided in the second hydraulic circuit  1520  by sequentially passing through the first hydraulic flow path  1401 , and the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . As described above, as the first valve  1411  and the fourth valve  1414  are provided as check valves allowing only the flow of the pressurized medium directing to the second hydraulic circuit  1520  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the third and fourth wheel cylinders  23  and  24 . Also, the third inlet valve  1521   a  and the fourth inlet valve  1521   b  provided in the second hydraulic circuit  1520  are maintained in an open state, and a second cut valve  1622  is maintained in a closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the second backup flow path  1620  side. 
     In the first braking mode, as the second dump check valve  1821  provided in the second dump flow path  1820  connected to the second pressure chamber  1340  allows the pressurized medium to be supplied from the reservoir  1100  to the second pressure chamber  1340 , the second pressure chamber  1340  may be filled with the pressurized medium, thereby preparing the second braking mode, which will be described later. 
     In the first braking mode in which braking of the wheel cylinders  20  is performed by the hydraulic pressure supply device  1300 , the first cut valve  1611  and the second cut valve  1621  provided in the first backup flow path  1610  and the second backup flow path  1620 , respectively, are switched to be closed, so that the pressurized medium discharged from the integrated master cylinder  1200  is prevented from being transferred to the wheel cylinders  20  side. 
     Specifically, because the first cut valve  1611  is closed when a pressing force is applied to the brake pedal  10 , the master chamber  1220   a  is sealed. Therefore, as the pressing force is applied to the brake pedal  10 , the pressurized medium accommodated in the master chamber  1220   a  is pressurized to generate a hydraulic pressure, the hydraulic pressure of the pressurized medium generated in the master chamber  1220   a  is transferred to the front surface (right side of  FIG. 2 ) of the first simulation piston  1230 , and the simulator valve  1261  is opened in the normal operation mode, so that a displacement is generated in the first simulation piston  1230 . On the other hand, because the inspection valve  1631  is closed in the normal operation mode of the electronic brake system  1000 , the second simulation chamber  1240   a  is sealed so that a displacement is not generated in the second simulation piston  1240 , and thus the elastic member  1250  is compressed by the displacement of the first simulation piston  1230 , and the elastic restoring force by the compression of the elastic member  1250  is provided to the driver as a pedal feeling. At this time, the pressurized medium accommodated in the first simulation chamber  1230   a  is discharged to the reservoir  1100  through the simulation flow path  1260 . 
     The electronic brake system  1000  according to the present embodiment may switch from the first braking mode to the second braking mode illustrated in  FIG. 3  when a braking pressure higher than that in the first braking mode is to be provided. 
       FIG. 3  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the present embodiment performs the second braking mode, and referring to  FIG. 3 , when a displacement or an operating speed of the brake pedal  10  detected by the pedal displacement sensor  11  is higher than a preset level or a hydraulic pressure detected by the pressure sensor is higher than a preset level, the electronic control unit may switch from the first braking mode to the second braking mode by determining that a higher braking pressure is required. 
     When the first braking mode is switched to the second braking mode, the motor operates to rotate in the other direction, and the rotational force of the motor is transferred to the hydraulic pressure providing unit by the power conversion unit so that the hydraulic piston  1320  moves backward, thereby generating a hydraulic pressure in the second pressure chamber  1340 . The hydraulic pressure discharged from the second pressure chamber  1340  is transferred to the respective wheel cylinders  20  through the hydraulic control unit  1400 , the first hydraulic circuit  1510 , and the second hydraulic circuit  1520 , thereby generating a braking force. 
     Specifically, the hydraulic pressure generated in the second pressure chamber  1340  is secondarily transferred to the first wheel cylinder  21  and the second wheel cylinder  22  provided in the first hydraulic circuit  1510  by sequentially passing through the second hydraulic flow path  1402 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 . At this time, as the second valve  1412  provided in the second hydraulic flow path  1402  is opened, the flow of the pressurized medium transferred along the second hydraulic flow path  1402  toward the third hydraulic flow path  1403  may be stably provided. The first inlet valve  1511   a  and the second inlet valve  1511   b  provided in the first hydraulic circuit  1510  are maintained in the open state, and the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550  are closed, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the reservoir  1100  side. 
     Also, the hydraulic pressure generated in the second pressure chamber  1340  is secondarily transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24  provided in the second hydraulic circuit  1520  by sequentially passing through the second hydraulic flow path  1402 , the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . 
     As the fourth valve  1414  provided in the fifth hydraulic flow path  1405  is provided as a check valve allowing only the flow of the pressurized medium directing to the second hydraulic circuit  1520  side from the second pressure chamber  1340 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24 . The third inlet valve  1521   a  and the fourth inlet valve  1521   b  provided in the second hydraulic circuit  1520  are maintained in the open state, and the second cut valve  1622  is maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the second backup flow path  1620  side. 
     In the second braking mode, as the first valve  1411  provided in the first hydraulic flow path  1401  is provided as a check valve blocking the flow of the pressurized medium directing to the first pressure chamber  1330 , the hydraulic pressure of the pressurizing medium generated in the second pressure chamber  1340  may be prevented from being transferred to the first pressure chamber  1330 . Also, as the first dump check valve  1811  provided in the first dump flow path  1810  connected to the first pressure chamber  1330  allows the pressurized medium to be supplied from the reservoir  1100  to the first pressure chamber  1330 , the first pressure chamber  1330  may be filled with the pressurized medium, thereby preparing the third braking mode, which will be described later. 
     Because an operation of the integrated master cylinder  1200  in the second braking mode is the same as the operation of the integrated master cylinder  1200  in the first braking mode described above, a description thereof will be omitted to prevent duplication of contents. 
     The electronic brake system  1000  according to the present embodiment may switch from the second braking mode to the third braking mode illustrated in  FIG. 4  when a braking pressure higher than that in the second braking mode is to be provided. 
       FIG. 4  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the present embodiment performs the third braking mode. 
     Referring to  FIG. 4 , when a displacement or an operating speed of the brake pedal  10  detected by the pedal displacement sensor  11  is higher than a preset level or a hydraulic pressure detected by the pressure sensor is higher than a preset level, the electronic control unit may switch from the second braking mode to the third braking mode by determining that a higher braking pressure is required. 
     When the second braking mode is switched to the third braking mode, the motor (not shown) operates to rotate in one direction, and the rotational force of the motor is transferred to the hydraulic pressure providing unit by the power conversion unit so that the hydraulic piston  1320  of the hydraulic pressure providing unit moves forward again, thereby generating a hydraulic pressure in the first pressure chamber  1330 . The hydraulic pressure discharged from the first pressure chamber  1330  is transferred to the respective wheel cylinders  20  through the hydraulic control unit  1400 , the first hydraulic circuit  1510 , and the second hydraulic circuit  1520 , thereby generating a braking force. 
     Specifically, the hydraulic pressure generated in the first pressure chamber  1330  is thirdly transferred to the first wheel cylinder  21  and the second wheel cylinder  22  provided in the first hydraulic circuit  1510  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 . At this time, as the first valve  1411  and the third valve  1413  are provided as check valves allowing only the flow of the pressurized medium directing to the first hydraulic circuit  1510  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the first and second wheel cylinders  21  and  22 . Also, the first inlet valve  1511   a  and the second inlet valve  1511   b  provided in the first hydraulic circuit  1510  are maintained in the open state, and the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550  are maintained in a closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the reservoir  1100  side. 
     Also, the hydraulic pressure of the pressurized medium generated in the first pressure chamber  1330  is thirdly transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24  provided in the second hydraulic circuit  1520  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . As described above, as the first valve  1411  and the fourth valve  1414  are provided as check valves allowing only the flow of the pressurized medium directing to the second hydraulic circuit  1520  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24 . The third inlet valve  1521   a  and the fourth inlet valve  1521   b  provided in the second hydraulic circuit  1520  are maintained in the open state, and the second cut valve  1622  is maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the second backup flow path  1620  side. 
     Because the hydraulic pressure of a high pressure is provided in the third braking mode, as the hydraulic piston  1320  moves forward, a force of the hydraulic pressure in the first pressure chamber  1330  to move the hydraulic piston  1320  backward also increases, so that a load applied to the motor increases rapidly. Accordingly, in the third braking mode, the second valve  1412  is operated to open, thereby allowing the flow of the pressurized medium through the second hydraulic flow path  1402 . In other words, a part of the hydraulic pressure generated in the first pressure chamber  1330  may be supplied to the second pressure chamber  1340  by sequentially passing through the first hydraulic flow path  1401  and the second flow path  1402 , and through this, the first pressure chamber  1330  and the second pressure chamber  1340  are in communication with each other to synchronize the hydraulic pressure, so that the load applied to the motor may be reduced and the durability and reliability of the devices may be improved. 
     Because an operation of the integrated master cylinder  1200  in the third braking mode is the same as the operation of the integrated master cylinder  1200  in the first braking mode described above, a description thereof will be omitted to prevent duplication of contents. 
     Hereinafter, an operation method of releasing the braking in the normal operation mode of the electronic brake system  1000  according to the present embodiment will be described. 
       FIG. 5  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the present embodiment releases the braking. 
     Referring to  FIG. 5 , when the pressing force applied to the brake pedal  10  is released, the motor generates a rotational force in any one direction and transmits the rotational force to the power conversion unit, and the power conversion unit returns the hydraulic piston  1320  to an original position thereof. As the hydraulic piston  1320  moves forward or backward to return to the original position, the hydraulic pressure generated in the first pressure chamber  1330  or the second pressure chamber  1340  may be transferred to the first hydraulic circuit  1510  or the second hydraulic circuit  1520  through the hydraulic control unit  1400  to be discharged to the reservoir  1100  side together with the hydraulic pressure of the pressurizing medium applied to the wheel cylinders  20 . 
     Specifically, the hydraulic pressure of the pressurized medium applied to the first wheel cylinder  21  and the second wheel cylinder  22  provided in the first hydraulic circuit  1510  may be discharged to the reservoir  1100  by sequentially passing through the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550 . To this end, the first and second outlet valves  1512   a  and  1512   b  may be switched to an open state, and the discharge valve  1550  may adjust the flow rate of the pressurized medium to be discharged to the reservoir  1100  by adjusting the opening degree depending on a displacement amount of the brake pedal  10 , thereby performing the pressure reduction braking or the braking release. At this time, as described above, the first inlet valve  1511   a  and the second inlet valve  1511   b  may be maintained in the open state so that the hydraulic pressure generated in the first pressure chamber  1330  or the second pressure chamber  1340  by the return of the hydraulic piston  1320  to the original position may also be discharged to the reservoir  1100  by sequentially passing through the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550 . 
     Also, the hydraulic pressure of the pressurized medium applied to the third wheel cylinder  23  and the fourth wheel cylinder  24  provided in the second hydraulic circuit  1520  may be discharged to the reservoir  1100  by sequentially passing through the second backup flow path  1620 , the first simulation chamber  1230   a,  and the simulation flow path  1260 . To this end, the second cut valve  1621  and the simulator valve  1261  may be switched to an open state, and at least one of the second cut valve  1621  and in response to a degree of pressure reduction of the hydraulic pressure applied to the first hydraulic circuit  1510  being adjusted by the discharge valve  1550 , the simulator valve  1261  may be provided as a solenoid valve that is linearly controlled to adjust the flow rate of the pressurized medium passing therethrough, like the discharge valve  1550 . At this time, as described above, the third inlet valve  1521   a  and the fourth inlet valve  152  lb may be maintained in the open state so that the hydraulic pressure generated in the first pressure chamber  1330  or the second pressure chamber  1340  by the return of the hydraulic piston  1320  to the original position may also be discharged to the reservoir  1100  by sequentially passing through the second backup flow path  1620 , the first simulation chamber  1230   a,  and the simulation flow path  1260 . 
     Hereinafter, the case in which the electronic brake system  1000  according to the present embodiment does not operate normally, that is, operates in the fallback mode will be described. 
       FIG. 6  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the present embodiment operates in the case in which the normal operation is impossible due to a device failure or the like, that is, in the case of the abnormal operation mode (fallback mode). 
     Referring to  FIG. 6 , in the abnormal operation mode, each of the valves is controlled to an initial braking state which is a non-operational state. At this time, when the driver depresses the brake pedal  10 , the master piston  1220  connected to the brake pedal  10  moves forward to generate a displacement. Because the first cut valve  1611  is provided in the open state in the non-operational state, by the forward movement of the master piston  1220 , the pressurized medium accommodated in the master chamber  1220   a  is transferred to the first wheel cylinder  21  and the second wheel cylinder  22  of the first hydraulic circuit  1510  along the first backup flow path  1610 , thereby performing braking. 
     Also, the pressurized medium accommodated in the master chamber  1220 a moves the first simulation piston  1230  forward to generate a displacement, so that the pressurized medium accommodated in the first simulation chamber  1230   a  is transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24  of the second hydraulic circuit  1520  along the second backup flow path  1620 , thereby performing braking. At the same time, the second simulation piston  1240  also generates a displacement by moving forward due to the displacement of the first simulation piston  1230 , so that the pressurized medium accommodated in the second simulation chamber  1240   a  may be provided to the second hydraulic circuit  1520  by joining into the second backup flow path  1620  along the auxiliary backup flow path  1630 . At this time, because the simulator valve  1261  is provided in a closed state in the non-operational state, the pressurized medium accommodated in the first simulation chamber  1230   a  may be transferred to the second backup flow path  1620  without being discharged to the reservoir  1100 , and at the same time, may generate a hydraulic pressure for moving the second simulation piston  1240  forward, and because the inspection valve  1631  and the second cut valve  1621  are provided in an open state, the pressurized medium accommodated in the first simulation chamber  1230   a  and the second simulation chamber  1240   a  may be transferred to the second backup flow path  1620 . 
     Hereinafter, the inspection mode of the electronic brake system  1000  according to the present embodiment will be described. 
       FIG. 7  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the present embodiment performs the inspection mode, and referring to  FIG. 7 , the electronic brake system  1000  according to the present embodiment may perform the inspection mode of inspecting whether a leak is generated in the integrated master cylinder  1200  or the simulator valve  1261 . When the inspection mode is performed, the electronic control unit controls to supply the hydraulic pressure generated from the hydraulic pressure supply device  1300  to the first simulation chamber  1230   a  of the integrated master cylinder  1200 . 
     Specifically, in a state in which each of the valves is controlled to the initial braking state, which is the non-operational state, the electronic control unit operates to move the hydraulic piston  1320  forward, so that a hydraulic pressure is generated in the first pressure chamber  1330 , the inspection valve  1631  and the first cut valve  1611  are switched to a closed state, and the second cut valve  1621  is maintained in the open state. Accordingly, as the hydraulic pressure generated in the first pressure chamber  1330  is transferred to the second hydraulic circuit  1520  side by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 , and the third inlet valve  1521   a  and the fourth inlet valve  152  lb are maintained in a normally open state, the pressurized medium transferred to the second hydraulic circuit  1520  is introduced into the first simulation chamber  1230   a  through the second backup flow path  1620 . At this time, the simulator valve  1261  is maintained in the closed state to induce the first simulation chamber  1230   a  to be in a sealed state. 
     In this state, by comparing an expected hydraulic pressure value of the pressurized medium to be generated by the displacement of the hydraulic piston  1320  with a hydraulic pressure value in the second hydraulic circuit  1520  or the first simulation chamber  1230   a  measured by the pressure sensor PS, a leak in the integrated master cylinder  1200  or the simulator valve  1261  may be diagnosed. Specifically, the expected hydraulic pressure value calculated based on a displacement amount of the hydraulic piston  1320  or a rotational angle measured by a motor control sensor (not shown) is compared with an actual hydraulic pressure value measured by the pressure sensor PS, and when the two hydraulic pressure values match, it may be determined that there is no leak in the integrated master cylinder  1200  or the simulator valve  1261 . On the other hand, when the actual hydraulic pressure value measured by the pressure sensor PS is lower than the expected hydraulic pressure value calculated based on the displacement amount of the hydraulic piston  1320  or the rotational angle measured by the motor control sensor (not shown), this is due to the loss of a part of the hydraulic pressure of the pressurized medium applied to the first simulation chamber  1230   a,  and thus it may be determined that there is a leak in the integrated master cylinder  1200  or the simulator valve  1261 , and this leak may be notified to the driver. 
     Hereinafter, an electronic brake system  2000  according to a second embodiment of the present disclosure will be described. 
       FIG. 8  is a hydraulic circuit diagram illustrating the electronic brake system  2000  according to the second embodiment of the present disclosure, and referring to  FIG. 8 , a fourth valve  2414  of a hydraulic control unit  2400  according to the second embodiment of the present disclosure is provided to perform cooperative control for a regenerative braking mode. 
     Because the following description of the electronic brake system  2000  according to the second embodiment of the present disclosure except for additional explanation with separate reference numerals is the same as the above description of the electronic brake system  1000  according to the first embodiment of the present disclosure, a description thereof will be omitted in order to prevent redundant description. 
     Recently, as the market demand for eco-friendly vehicles increases, hybrid vehicles with improved fuel efficiency are gaining popularity. The hybrid vehicle recovers kinetic energy as electric energy while braking the vehicle, stores the electric energy in a battery, and then utilizes the motor as an auxiliary driving source of the vehicle, and the hybrid vehicle typically recovers energy by a generator (not shown) or the like during a braking operation of the vehicle in order to increase the energy recovery rate. This braking operation is referred to as a regenerative braking mode, and in the electronic brake system  2000  according to the present embodiment, a generator (not shown) may be provided in the third wheel cylinder  23  and the fourth wheel cylinder  24  of the second hydraulic circuit  1520  to implement the regenerative braking mode. The generator and the fourth valve  2414  in the third and fourth wheel cylinders  23  and  24  may perform the regenerative braking mode through cooperative control. 
     The fourth valve  2414  provided in the fifth hydraulic flow path  1405  may be provided as a bidirectional control valve for controlling the flow of the pressurized medium transferred along the fifth hydraulic flow path  1405 . The fourth valve  2414  may be provided as a normally closed type solenoid valve that operates to be opened when an electric signal is received from the electronic control unit in a normally closed state. The fourth valve  2414  is controlled to be opened in a normal operation mode of the electronic brake system  2000 , and may be switched to a closed state when entering the regenerative braking mode by the generator (not shown) provided in the third wheel cylinder  23  and the fourth wheel cylinder  24 . 
     Hereinafter, the regenerative braking mode of the electronic brake system  2000  according to the second embodiment of the present disclosure will be described. 
       FIG. 9  is a hydraulic circuit diagram illustrating that the electronic brake system  2000  according to the second embodiment of the present disclosure performs the regenerative braking mode, and referring to  FIG. 9 , while in the case of the first wheel cylinder  21  and the second wheel cylinder  22  of the first hydraulic circuit  1510 , a braking force that the driver intends to implement is only generated by the hydraulic pressure of the pressurized medium by the operation of the hydraulic pressure supply device  1300 , in the case of the third wheel cylinder  23  and the fourth wheel cylinder  24  of the second hydraulic circuit  1520  in which an energy recovery device such as a generator is installed, the sum of the braking pressure of the pressurized medium by the hydraulic pressure supply device  1300  and the total braking pressure plus the regenerative braking pressure by the generator should be equal to the total braking force of the first wheel cylinder  21  and the second wheel cylinder  22 . 
     Therefore, when entering the regenerative braking mode, as the braking pressure by the hydraulic pressure supply device  1300  applied to the third wheel cylinder  23  and the fourth wheel cylinder  24  is removed or maintained constant by closing the fourth valve  2414 , and at the same time the regenerative braking pressure by the generator is increased, the total braking force of the third and fourth wheel cylinders  23  and  24  may be equal to the braking force of the first and second wheel cylinders  21  and  22 . 
     Specifically, when the driver depresses the brake pedal  10  to brake the vehicle, the motor (not shown) operates to rotate in one direction, the rotational force of the motor is transferred to the hydraulic pressure providing unit by the power conversion unit, and the hydraulic piston  1320  of the hydraulic pressure providing unit moves forward, thereby generating a hydraulic pressure in the first pressure chamber  1330 . The hydraulic pressure discharged from the first pressure chamber  1330  is transferred to the respective wheel cylinders  20  through the hydraulic control unit  1400 , the first hydraulic circuit  1510  and the second hydraulic circuit  1520 , thereby generating a braking force. 
     In the case of the first hydraulic circuit  1510  in which an energy recovery device such as a generator is not installed, the hydraulic pressure of the pressurized medium generated in the first pressure chamber  1330  sequentially passes through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 , and is transferred to the first and second wheel cylinders  21  and  22 , thereby performing braking. As described above, as the first valve  1411  and the third valve  1413  allow the flow of the pressurized medium directing to the first hydraulic circuit  1510  from the first pressure chamber  1330 , the hydraulic pressure of the pressurizing medium generated in the first pressure chamber  1330  may be transferred to the first hydraulic circuit  1510 . 
     On the other hand, in the case of the second hydraulic circuit  1520  in which the generator is installed, when the electronic control unit determines that it is possible to enter the regenerative braking mode by sensing a speed, deceleration, etc. of the vehicle, the electronic control unit may close the fourth valve  2414  to block transmission of the hydraulic pressure of the pressurized medium to the third wheel cylinder  23  and the fourth wheel cylinder  24 , and may implement regenerative braking by the generator. Thereafter, when the electronic control unit determines that the vehicle is in an unsuitable state for regenerative braking, or the braking pressure in the first hydraulic circuit  1510  and the braking pressure in the second hydraulic circuit  1520  are different, the electronic control unit may control the hydraulic pressure of the pressurizing medium to be transferred to the second hydraulic circuit  1520  by switching the fourth valve  2414  to an open state, and the at the same time may synchronize the braking pressure in the first hydraulic circuit  1510  and the braking pressure in the second hydraulic circuit  1520 . Accordingly, the braking pressure or braking force applied to the first to fourth wheel cylinders  20  may be uniformly controlled, so that in addition to braking stability of the vehicle, oversteering or understeering may be prevented to improve driving stability of the vehicle. 
     Hereinafter, an electronic brake system  3000  according to a third embodiment of the present disclosure will be described. 
       FIG. 10  is a hydraulic circuit diagram illustrating the electronic brake system  3000  according to the third embodiment of the present disclosure, and referring to  FIG. 10 , a hydraulic control unit  3400  according to the third embodiment of the present disclosure may be provided to further include a sixth hydraulic flow path  3406  connecting the first hydraulic flow path  1401  and the second hydraulic flow path  1402 , and a fifth valve  3415  provided in the sixth hydraulic flow path  3406  to control the flow of the pressurized medium, and a second valve  3412  provided in the second hydraulic flow path  1402  may be provided as a check valve allowing only the flow of the pressurized medium discharged from the second pressure chamber  1340 . 
     Because the following description of the electronic brake system  3000  according to the third embodiment of the present disclosure except for additional explanation with separate reference numerals is the same as the above description of the electronic brake system  1000  according to the first embodiment of the present disclosure, a description thereof will be omitted in order to prevent redundant description. 
     The second valve  3412  provided in the second hydraulic flow path  1402  may be provided as a check valve allowing only the flow of the pressurized medium directing to the third hydraulic flow path  1403  from the second pressure chamber  1340  and blocking the flow of the pressurized medium in the opposite direction. 
     The sixth hydraulic flow path  3406  is provided to connect the first hydraulic flow path  1401  and the second hydraulic flow path  1402 . Specifically, one end of the sixth hydraulic flow path  3406  may be connected between the first pressure chamber  1330  and the first valve  1411  on the first hydraulic flow path  1401 , and the other end thereof may be connected between the second pressure chamber  1340  and the second valve  3412  on the second hydraulic flow path  1402 . The fifth valve  3415  is provided in the sixth hydraulic flow path  3406  to control the flow of the pressurized medium, and may be provided as a bidirectional control valve for controlling the flow of the pressurized medium transferred along the second hydraulic flow path  1402 . The fifth valve  3415  may be provided as a normally closed type solenoid valve that operates to be opened when an electric signal is received from the electronic control unit in a normally closed state. The fifth valve  3415  may be controlled to be opened in a third braking mode of a normal operation mode of the electronic brake system  3000 . A detailed description thereof will be given later with reference to  FIG. 13 . 
     Hereinafter, an operation method of the electronic brake system  3000  according to the third embodiment of the present disclosure will be described. 
     The normal operation mode of the electronic brake system  3000  according to the third embodiment of the present disclosure may be classified into a first braking mode, a second braking mode, and the third braking mode as the hydraulic pressure transferred from the hydraulic pressure supply device  1300  to the wheel cylinders  20  increases. Specifically, in the first braking mode, the hydraulic pressure may be firstly provided to the wheel cylinders  20  by the hydraulic pressure supply device  1300 , in the second braking mode, the hydraulic pressure may be secondarily provided to the wheel cylinders  20  by the hydraulic pressure supply device  1300  to transfer a higher braking pressure than in the first braking mode, and in the third braking mode, the hydraulic pressure may be thirdly provided to the wheel cylinders  20  by the hydraulic pressure supply device  1300  to transfer a higher braking pressure than in the second braking mode. 
     The first to third braking modes may be changed by varying the operations of the hydraulic pressure supply device  1300  and the hydraulic control unit  3400 . The hydraulic pressure supply device  1300  may provide a sufficiently high hydraulic pressure of the pressurized medium without a high specification motor by utilizing the first to third braking modes, and furthermore, may prevent unnecessary loads applied to the motor. Therefore, a stable braking force may be secured while reducing the cost and weight of the brake system, and durability and operational reliability of the devices may be improved. 
       FIG. 11  is a hydraulic circuit diagram illustrating that the electronic brake system  3000  according to the third embodiment of the present disclosure performs the first braking mode. 
     Referring to  FIG. 11 , when the driver depresses the brake pedal  10  at the beginning of braking, the motor (not shown) operates to rotate in one direction, the rotational force of the motor is transferred to the hydraulic pressure providing unit by the power conversion unit, and the hydraulic piston  1320  of the hydraulic pressure providing unit moves forward, thereby generating a hydraulic pressure in the first pressure chamber  1330 . The hydraulic pressure discharged from the first pressure chamber  1330  is transferred to the respective wheel cylinders  20  through the hydraulic control unit  1400 , the first hydraulic circuit  1510  and the second hydraulic circuit  1520 , thereby generating a braking force. 
     Specifically, the hydraulic pressure generated in the first pressure chamber  1330  is primarily transferred to the first wheel cylinder  21  and the second wheel cylinder  22  provided in the first hydraulic circuit  1510  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 . At this time, the fifth valve  3415  is maintained in a closed state to prevent the hydraulic pressure generated in the first pressure chamber  1330  from leaking into the second pressure chamber  1340  along the sixth hydraulic flow path  3406 . Also, as the first valve  1411  and the third valve  1413  are provided as check valves allowing only the flow of the pressurized medium directing to the first hydraulic circuit  1510  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the first and second wheel cylinders  21  and  22 . The first inlet valve  1511   a  and the second inlet valve  1511 b provided in the first hydraulic circuit  1510  are maintained in the open state, and the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550  are maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the reservoir  1100  side. 
     The hydraulic pressure of the pressurized medium generated in the first pressure chamber  1330  is primarily transferred to the third and fourth wheel cylinders  23  and  24  provided in the second hydraulic circuit  1520  by sequentially passing through the first hydraulic flow path  1401 , and the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . As described above, the fifth valve  3415  is maintained in the closed state to prevent the hydraulic pressure generated in the first pressure chamber  1330  from leaking into the second pressure chamber  1340  side along the sixth hydraulic flow path  3406 , and as the first valve  1411  and the fourth valve  1414  are provided as check valves allowing only the flow of the pressurized medium directing to the second hydraulic circuit  1520  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the third and fourth wheel cylinders  23  and  24 . The third inlet valve  1521   a  and the fourth inlet valve  152  lb provided in the second hydraulic circuit  1520  are maintained in the open state, and the second cut valve  1622  is maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the second backup flow path  1620  side. 
     In the first braking mode, as the second dump check valve  1821  provided in the second dump flow path  1820  connected to the second pressure chamber  1340  allows the pressurized medium to be supplied from the reservoir  1100  to the second pressure chamber  1340 , the second pressure chamber  1340  may be filled with the pressurized medium, thereby preparing the second braking mode, which will be described later. 
     Because an operation of the integrated master cylinder  1200  in the first braking mode is the same as the operation of the integrated master cylinder  1200  in the first to third braking modes of the electronic brake system according to the first embodiment described above, a description thereof will be omitted to prevent duplication of contents. 
     The electronic brake system  3000  according to the third embodiment of the present disclosure may switch from the first braking mode to the second braking mode illustrated in  FIG. 12  when a braking pressure higher than that in the first braking mode is to be provided. 
       FIG. 12  is a hydraulic circuit diagram illustrating that the electronic brake system  3000  according to the third embodiment of the present disclosure performs the second braking mode, and referring to  FIG. 12 , when a displacement or an operating speed of the brake pedal  10  detected by the pedal displacement sensor  11  is higher than a preset level or a hydraulic pressure detected by the pressure sensor is higher than a preset level, the electronic control unit may switch from the first braking mode to the second braking mode by determining that a higher braking pressure is required. 
     When the first braking mode is switched to the second braking mode, the motor operates to rotate in the other direction, and the rotational force of the motor is transferred to the hydraulic pressure providing unit by the power conversion unit so that the hydraulic piston  1320  moves backward, thereby generating a hydraulic pressure in the second pressure chamber  1340 . The hydraulic pressure discharged from the second pressure chamber  1340  is transferred to the respective wheel cylinders  20  through the hydraulic control unit  1400 , the first hydraulic circuit  1510 , and the second hydraulic circuit  1520 , thereby generating a braking force. 
     Specifically, the hydraulic pressure generated in the second pressure chamber  1340  is secondarily transferred to the first wheel cylinder  21  and the second wheel cylinder  22  provided in the first hydraulic circuit  1510  by sequentially passing through the second hydraulic flow path  1402 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 . At this time, the fifth valve  3415  is maintained in the closed state to prevent the hydraulic pressure generated in the second pressure chamber  1340  from leaking into the first pressure chamber  1330  side along the sixth hydraulic flow path  3406 . Also, as the second valve  3412  and the third valve  1413  are provided as check valves allowing only the flow of the pressurized medium directing to the first hydraulic circuit  1510  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the first and second wheel cylinders  21  and  22 . The first inlet valve  1511   a  and the second inlet valve  1511 b provided in the first hydraulic circuit  1510  are maintained in the open state, and the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550  are maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the reservoir  1100  side. 
     Also, the hydraulic pressure generated in the second pressure chamber  1340  is secondarily transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24  provided in the second hydraulic circuit  1520  by sequentially passing through the second hydraulic flow path  1402 , the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . At this time, as described above, the fifth valve  3415  is maintained in the closed state to prevent the hydraulic pressure generated in the second pressure chamber  1340  from leaking into the first pressure chamber  1330  side along the sixth hydraulic flow path  3406 , and as the fourth valve  1414  provided in the fifth hydraulic flow path  1405  is provided as check valves allowing only the flow of the pressurized medium directing to the second hydraulic circuit  1520  side from the second pressure chamber  1340 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24 . The third inlet valve  1521   a  and the fourth inlet valve  152  lb provided in the second hydraulic circuit  1520  are maintained in the open state, and the second cut valve  1622  is maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the second backup flow path  1620  side. 
     In the second braking mode, as the first dump check valve  1811  provided in the first dump flow path  1810  connected to the first pressure chamber  1330  allows the pressurized medium to be supplied from the reservoir  1100  to the first pressure chamber  1330 , the first pressure chamber  1330  may be filled with the pressurized medium, thereby preparing the third braking mode, which will be described later. 
     Because an operation of the integrated master cylinder  1200  in the second braking mode is the same as the operation of the integrated master cylinder  1200  in the first to third braking modes of electronic brake system described above, a description thereof will be omitted to prevent duplication of contents. 
     The electronic brake system  3000  according to the third embodiment of the present disclosure may switch from the second braking mode to the third braking mode illustrated in  FIG. 13  when a braking pressure higher than that in the second braking mode is to be provided. 
       FIG. 13  is a hydraulic circuit diagram illustrating that the electronic brake system  3000  according to the third embodiment of the present disclosure performs the third braking mode. 
     Referring to  FIG. 13 , when a displacement or an operating speed of the brake pedal  10  detected by the pedal displacement sensor  11  is higher than a preset level or a hydraulic pressure detected by the pressure sensor is higher than a preset level, the electronic control unit may switch from the second braking mode to the third braking mode by determining that a higher braking pressure is required. 
     When the second braking mode is switched to the third braking mode, the motor (not shown) operates to rotate in one direction, and the rotational force of the motor is transferred to the hydraulic pressure providing unit by the power conversion unit so that the hydraulic piston  1320  of the hydraulic pressure providing unit moves forward again, thereby generating a hydraulic pressure in the first pressure chamber  1330 . The hydraulic pressure discharged from the first pressure chamber  1330  is transferred to the respective wheel cylinders  20  through the hydraulic control unit  3400 , the first hydraulic circuit  1510 , and the second hydraulic circuit  1520 , thereby generating a braking force. 
     Specifically, the hydraulic pressure generated in the first pressure chamber  1330  is thirdly transferred to the first wheel cylinder  21  and the second wheel cylinder  22  provided in the first hydraulic circuit  1510  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 . At this time, as the first valve  1411  and the third valve  1413  are provided as check valves allowing only the flow of the pressurized medium directing to the first hydraulic circuit  1510  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the first and second wheel cylinders  21  and  22 . The first inlet valve  1511   a  and the second inlet valve  1511   b  provided in the first hydraulic circuit  1510  are maintained in the open state, and the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550  are maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the reservoir  1100  side. 
     Also, the hydraulic pressure of the pressurized medium generated in the first pressure chamber  1330  is thirdly transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24  provided in the second hydraulic circuit  1520  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . As described above, as the first valve  1411  and the fourth valve  1414  are provided as check valves allowing only the flow of the pressurized medium directing to the second hydraulic circuit  1520  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24 . Also, the third inlet valve  1521   a  and the fourth inlet valve  1521   b  provided in the second hydraulic circuit  1520  are maintained in the open state, and the second cut valve  1622  is maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the second backup flow path  1620  side. 
     Because the hydraulic pressure of a high pressure is provided in the third braking mode, as the hydraulic piston  1320  moves forward, a force of the hydraulic pressure in the first pressure chamber  1330  to move the hydraulic piston  1320  backward also increases, so that a load applied to the motor increases rapidly. Accordingly, in the third braking mode, the fifth valve  3415  is operated to open, thereby allowing the flow of the pressurized medium through the sixth hydraulic flow path  3406 . In other words, a part of the hydraulic pressure generated in the first pressure chamber  1330  may be supplied to the second pressure chamber  1340  by sequentially passing through the first hydraulic flow path  1401 , the sixth hydraulic flow path  3406 , and the second flow path  1402 , and through this, the first pressure chamber  1330  and the second pressure chamber  1340  are in communication with each other to synchronize the hydraulic pressure, so that the load applied to the motor may be reduced and the durability and reliability of the devices may be improved. 
     Because an operation of the integrated master cylinder  1200  in the third braking mode is the same as the operation of the integrated master cylinder  1200  in the first to third braking modes of electronic brake system described above, a description thereof will be omitted to prevent duplication of contents. 
     Also, because an operation method of releasing the braking in the normal operation mode of the electronic brake system  3000  according to the third embodiment of the present disclosure is the same as the operation method of releasing the braking in the normal operation mode of the electronic brake system  1000  according to the first embodiment of the present disclosure described above, a separate description thereof will be omitted. 
     Hereinafter, an electronic brake system  4000  according to a fourth embodiment of the present disclosure will be described. 
       FIG. 14  is a hydraulic circuit diagram illustrating the electronic brake system  4000  according to the fourth embodiment of the present disclosure, and referring to  FIG. 14 , an integrated master cylinder  4200  according to the fourth embodiment may further include a first simulator spring  4271  provided to elastically support the first simulation piston  1230 , and a second simulator spring  4272  provided to elastically support the second simulation piston  4272 . 
     Because the following description of the electronic brake system  4000  according to the fourth embodiment of the present disclosure except for additional explanation with separate reference numerals is the same as the above description of the electronic brake system  3000  according to the third embodiment of the present disclosure, a description thereof will be omitted in order to prevent redundant description. 
     The first simulator spring  4271  is provided to elastically support the first simulation piston  1230 . To this end, one end of the first simulation spring  4271  may be supported on the rear surface (left surface of  FIG. 14 ) of the first simulation piston  1230 , and the other end thereof may be supported on the front surface (right surface of  FIG. 14 ) of the second simulation piston  1240 . When the first simulation piston  1230  moves forward according to a braking operation to generate a displacement, the first simulator spring  4271  is compressed, and at this time, a pedal feeling may be provided to the driver together with the elastic member  1250  by the elastic restoring force. Thereafter, when the braking is released, as the first simulator spring  4271  expands by an elastic force thereof, the first simulation piston  1230  may return to the original position. 
     The second simulator spring  4272  is provided to elastically support the second simulation piston  1240 . As one end of the second simulator spring  4272  is supported on the cylinder block  1210  and the other end thereof is supported on the second simulation piston  1240 , the second simulator spring  4272  may elastically support the second simulation piston  1240 . When the second simulation piston  1240  moves forward according to the braking operation to generate a displacement, the second simulator spring  4272  is compressed, and thereafter, when the braking is released, as the second simulator spring  4272  expands by an elastic force thereof, the second simulation piston  1240  may return to the original position. 
     Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. The following embodiment is provided to fully convey the spirit of the present disclosure to a person having ordinary skill in the art to which the present disclosure belongs. The present disclosure is not limited to the embodiment shown herein but may be embodied in other forms. The drawings are not intended to limit the scope of the present disclosure in any way, and the size of components may be exaggerated for clarity of illustration. 
       FIG. 1  is a hydraulic circuit diagram illustrating an electronic brake system  1000  according to a first embodiment of the present disclosure. 
     Referring to  FIG. 1 , the electronic brake system  1000  according to the first embodiment of the present disclosure includes a reservoir  1100  in which a pressurized medium is stored, an integrated master cylinder  1200  provided to provide a reaction force against pressing of a brake pedal  10  to a driver and pressurize and discharge the pressurized medium such as brake oil accommodated therein, a hydraulic pressure supply device  1300  provided to receive an electrical signal corresponding to a pressing force by a driver from a pedal displacement sensor  11  that detects a displacement of the brake pedal  10  and to generate a hydraulic pressure of the pressurized medium through a mechanical operation, a hydraulic control unit  1400  provided to control the hydraulic pressure provided from the hydraulic pressure supply device  1300 , hydraulic circuits  1510  and  1520  having wheel cylinders  20  for braking respective wheels RR, RL, FR, and FL as the hydraulic pressure of the pressurized medium is transferred, a dump controller  1800  provided between the hydraulic pressure supply device  1300  and the reservoir  1100  to control a flow of the pressurized medium, backup flow paths  1610  and  1620  are provided to hydraulically connect the integrated master cylinder  1200  and the hydraulic circuits  1510  and  1520 , a reservoir flow path  1700  provided to hydraulically connect the reservoir  1100  and the integrated master cylinder  1200 , and an electronic control unit (ECU, not shown) provided to control the hydraulic pressure supply device  1300  and various valves based on hydraulic pressure information and pedal displacement information. 
     The integrated master cylinder  1200  includes simulation chambers  1230   a  and  1240   a,  and a master chamber  1220   a  to, when the driver presses the brake pedal  10  for braking operation, provide a reaction force against the pressing to the driver to provide a stable pedal feel, and at the same time pressurize and discharge the pressurized medium accommodated therein. 
     The integrated master cylinder  1200  may be divided into a pedal simulation part to provide a pedal feel to the driver, and a master cylinder part to transfer the pressurized medium to the first hydraulic circuit  1510  side, which will be described later. The integrated master cylinder  1200  may be configured such that the master cylinder part and the pedal simulation part are sequentially provided from the brake pedal  10  side and disposed coaxially within a cylinder block  1210 . 
     Specifically, the integrated master cylinder  1200  may include the cylinder block  1210  having a chamber formed therein, the master chamber  1220   a  formed on an inlet side of the cylinder block  1210  to which the brake pedal  10  is connected, a master piston  1220  provided in the master chamber  1220   a  and connected to the brake pedal  10  to be displaceable depending on the operation of the brake pedal  10 , a piston spring  1220   b  provided to elastically support the master piston  1220 , the first simulation chamber  1230   a  formed more inside than the master chamber  1220   a  on the cylinder block  1210 , a first simulation piston  1230  provided in the first simulation chamber  1230   a  to be displaceable by a displacement of the master piston  1220  or a hydraulic pressure of the pressurized medium accommodated in the master chamber  1220   a,  the second simulation chamber  1240   a  formed more inside than the first simulation chamber  1230   a  on the cylinder block  1210 , a second simulation piston  1240  provided in the second simulation chamber  1240   a  to be displaceable by a displacement of the first simulation chamber  1230   a  or a hydraulic pressure of the pressurized medium accommodated in the first simulation chamber  1230   a,  an elastic member  1250  disposed between the first simulation piston  1230  and the second simulation piston  1240  to provide a pedal feeling through an elastic restoring force generated during compression, a simulator spring  1270  provided to elastically support the second simulation piston  1240 , a simulation flow path  1260  provided to connect the first simulation chamber  1230   a  and the reservoir  1100 , and a simulator valve  1261  provided in the simulation flow path  1260  to control the flow of the pressurized medium. 
     The master chamber  1220   a,  the first simulation chamber  1230   a,  and the second simulation chamber  1240   a  may be sequentially formed toward the inside (left side of  FIG. 1 ) from the brake pedal  10  side (right side of  FIG. 1 ) on the cylinder block  1210  of the integrated master cylinder  1200 . Also, the master piston  1220 , the first simulation piston  1230 , and the second simulation piston  1240  are disposed in the master chamber  1220   a,  the first simulation chamber  1230   a,  and the second simulation chamber  1240   a,  respectively, to generate a hydraulic pressure or a negative pressure by the pressurized medium accommodated in the respective chambers depending on forward or backward movement. 
     The master chamber  1220   a  may be formed on the inlet side or the outermost side (right side of  FIG. 1 ) of the cylinder block  1210 , and the master piston  1220  connected to the brake pedal  10  via an input rod  12  may be accommodated in the master chamber  1220   a  to enable reciprocating movement. 
     The pressurized medium may be introduced into and discharged from the master chamber  1220   a  through a first hydraulic port  1280   a  and a second hydraulic port  1280   b.  The first hydraulic port  1280   a  is connected to a first reservoir flow path  1710 , which will be described later, so that the pressurized medium may be introduced into the master chamber  1220   a  from the reservoir  1100 , and the second hydraulic port  1280   b  is connected to a first backup flow path  1610 , which will be described later, so that the pressurized medium may be discharged into the first backup flow path  1610  side from the master chamber  1220   a,  or conversely, the pressurized medium may be introduced into the master chamber  1220   a  side from the first backup flow path  1610 . A pair of sealing members  1290   a  are provided in front and rear of the first hydraulic port  1280   a  to prevent leakage of the pressurized medium. The pair of sealing members  1290   a  may allow the flow of the pressurized medium directing to the first master chamber  1220   a  from the reservoir  1100  through the first reservoir flow path  1710  while blocking the flow of the pressurized medium directing to the first reservoir flow path  1710  from the first master chamber  1220   a.    
     The master piston  1220  may be accommodated in the master chamber  1220 a to generate a hydraulic pressure by pressurizing the pressurized medium accommodated in the master chamber  1220   a  by moving forward (left direction of  FIG. 1 ) or to generate a negative pressure inside the master chamber  1220   a  by moving backward (right direction of  FIG. 1 ). The master piston  1220  may be elastically supported by the piston spring  1220   b,  and the piston spring  1220   b  may be provided with one end supported by the cylinder block  1210  and the other end supported by a flange portion formed by extending outwardly from an end of the master piston  1220 . 
     The first simulation chamber  1230   a  may be formed at an inner side (left side of  FIG. 1 ) of the master chamber  1220   a  on the cylinder block  1210 , and the first simulation piston  1230  may be accommodated in the first simulation chamber  1230 a to enable reciprocating movement. 
     The pressurized medium may be introduced into and discharged from the first simulation chamber  1230   a  through a third hydraulic port  1280   c  and a fourth hydraulic port  1280   d.  The third hydraulic port  1280   c  is connected to a second reservoir flow path  1720  and the simulation flow path  1260 , which will be described later, so that the pressurized medium accommodated in the first simulation chamber  1230   a  may be discharged into the reservoir  1100  side, or conversely, the pressurized medium may be introduced from the reservoir  1100 . The fourth hydraulic port  1280   d  is connected to the second backup flow path  1620 , which will be described later, so that the pressurized medium accommodated in the first simulation chamber  1230   a  may be discharged into the second hydraulic circuit  1520  side, or conversely, the pressurized medium may be introduced into the first simulation chamber  1230   a  side from the second backup flow path  1620 . 
     The first simulation piston  1230  may be accommodated in the first simulation chamber  1230   a  to generate a hydraulic pressure of the pressurized medium accommodated in the first simulation chamber  1230   a  or press the elastic member  1250 , which will be described later, by moving forward, or to generate a negative pressure inside the first simulation chamber  1230   a  or return the elastic member  1250  to an original position and shape thereof by moving backward. At least one sealing member  1290   b  may be provided between an inner wall of the cylinder block  1210  and an outer circumferential surface of the first simulation piston  1230  to prevent leakage of the pressurized medium between the adjacent chambers. 
     A step portion formed to be stepped may be provided at a portion where the first simulation chamber  1230   a  is formed on the cylinder block  1210 , and an extension portion provided to be caught on the step portion by expanding outwardly may be provided on the outer circumferential surface of the first simulation piston  1230 . As the extension portion of the first simulation piston  1230  is provided to be caught on the step portion of the cylinder block  1210 , in order for the first simulation piston  1230  to return to an original position thereof after moving forward by the operation of the brake pedal  10 , a backward stroke degree of the first simulation piston  1230  when moving backward may be limited. 
     The second simulation chamber  1240   a  may be formed at an inner side (left side of  FIG. 1 ) of the first simulation chamber  1230   a  on the cylinder block  1210 , and the second simulation piston  1240  may be accommodated in the second simulation chamber  1240   a  to enable reciprocating movement. 
     The pressurized medium may be introduced into and discharged from the second simulation chamber  1240   a  through a fifth hydraulic port  1280   e  and a sixth hydraulic port  1280 f. Specifically, the fifth hydraulic port  1280   e  is connected to a third reservoir flow path  1730 , which will be described later, so that the pressurized medium may be introduced into the second simulation chamber  1240   a  side from the reservoir  1100  or discharged from the second simulation chamber  1240  to the reservoir  1100  side. The sixth hydraulic port  1280 f is connected to an auxiliary backup flow path  1630 , which will be described later, so that the pressurized medium accommodated in the second simulation chamber  1240   a  may be discharged into the second backup flow path  1620  side, or conversely, the pressurized medium may be introduced into the second simulation chamber  1240   a  side from the second backup flow path  1620  side. 
     The second simulation piston  1240  may be accommodated in the second simulation chamber  1240   a  to generate a hydraulic pressure of the pressurized medium accommodated in the second simulation chamber  1240   a  by moving forward, or to generate a negative pressure inside the second simulation chamber  1240   a  by moving backward. At least one sealing member  1290   c  may be provided between the inner wall of the cylinder block  1210  and an outer circumferential surface of the second simulation piston  1240  to prevent leakage of the pressurized medium between the adjacent chambers. The sealing member  1290   c  may allow the flow of the pressurized medium directing to the second simulation chamber  1240   a  from the reservoir  1100  through the third reservoir flow path  1730  while blocking the flow of the pressurized medium directing to the third reservoir flow path  1730  from the second simulation chamber  1240   a.    
     The integrated master cylinder  1200  according to the present embodiment may secure safety in the event of a failure of a device by including the master chamber  1220   a  and the simulation chambers  1230   a  and  1240   a.  For example, the master chamber  1220   a  may be connected to the wheel cylinders  20  of any two of a right front wheel FR, a left front wheel FL, a left rear wheel RL, and a right rear wheel RR through the first backup flow path  1610 , which will be described later, and the simulation chambers  1230   a  and  1240   a  may be connected to the wheel cylinders  20  of the other two through the second backup flow path  1620  and the auxiliary backup flow path  1630 , which will be described later, and thus even when a problem such as a leak in any one of the chambers occurs, it may be possible to brake the vehicle. A detailed description thereof will be given later with reference to  FIG. 6 . 
     The elastic member  1250  is interposed between the first simulation piston  1230  and the second simulation piston  1240  to provide a pedal feeling of the brake pedal  10  to the driver by its own elastic restoring force. The elastic member  1250  may be made of a material such as compressible and expandable rubber, and when a displacement occurs in the first simulation piston  1230  by the operation of the brake pedal  10 , but when the second simulation piston  1240  is maintained in an original position thereof, the elastic member  1250  is compressed, and the driver may receive a stable and familiar pedal feeling by the elastic restoring force of the compressed elastic member  1250 . A detailed description thereof will be given later. 
     Accommodating grooves recessed in a shape corresponding to the shape of the elastic member  1250  to facilitate smooth compression and deformation of the elastic member  1250  may be provided on a rear surface (left surface of  FIG. 1 ) of the first simulation piston  1230  and a front surface (right surface of  FIG. 1 ) of the second simulation piston  1240 , which face the elastic member  1250 , respectively. 
     The simulator spring  1270  is provided to elastically support the second simulation piston  1240 . The simulator spring  1270  has one end supported by the cylinder block  1210  and the other end supported by the second simulation piston  1240 , thereby resiliently supporting the second simulation piston  1240 . When the second simulation piston  1240  moves forward according to a braking operation to generate a displacement, the simulator spring  1270  is compressed, and thereafter, when the braking is released, as the simulator spring  1270  expands by an elastic force thereof, the second simulation piston  1240  may return to the original position. 
     The simulation flow path  1260  is provided such that the first simulation chamber  1230   a  and the reservoir  1100  are in communication with each other, and the simulator valve  1261  for controlling bidirectional flows of the pressurized medium may be provided in the simulation flow path  1260 . The simulator valve  1261  may be provided as a normally closed type solenoid valve that operates to be opened when an electric signal is received from the electronic control unit in a normally closed state. The simulator valve  1261  may be opened in a normal operation mode of the electronic brake system  1000 . 
     Explaining a pedal simulation operation by the integrated master cylinder  1200 , at the same time as the driver operates the brake pedal  10  in a normal operation, a first cut valve  1611  and a second cut valve  1621  provided in the first backup flow path  1610  and the second backup flow path  1620 , which will be described later, respectively, are closed, while the simulator valve  1261  in the simulation flow path  1260  is opened. As the operation of the brake pedal  10  progresses, the master piston  1220  moves forward, but the master chamber  1220   a  is sealed by a closing operation of the first cut valve  1611 , so that as the hydraulic pressure of the pressurized medium accommodated in the master chamber  1220   a  is transferred to the first simulation piston  1230 , the first simulation piston  1230  moves forward to generate a displacement. On the other hand, as the second cut valve  1621  is closed, the second simulation chamber  1240   a  is sealed so that a displacement of the second simulation piston  1240  is not generated, and thus the elastic member  1250  is compressed by the displacement of the first simulation piston  1230 , and the elastic restoring force by compression of the elastic member  1250  may be provided to the driver as the pedal feeling. At this time, the pressurized medium accommodated in the first simulation chamber  1230   a  is transferred to the reservoir  1100  through the simulation flow path  1260 . Thereafter, when the driver releases the pressing force of the brake pedal  10 , the piston spring  1220   b  and the elastic member  1250  return to the original shape and position thereof by the elastic restoring force, and the first simulation chamber  1230   a  may be filled with the pressurized medium supplied from the reservoir  1100  through the simulation flow path  1260 . 
     As such, because the insides of the first simulation chamber  1230   a  and the second simulation chamber  1240   a  are always filled with the pressurized medium, when the pedal simulation is operated, friction of the first simulation piston  1230  and the second simulation piston  1240  is minimized, so that the durability of the integrated master cylinder  1200  is improved and at the same time the inflow of foreign substances from the outside may be blocked. 
     A case in which the electronic brake system  1000  operates abnormally, that is, an operation of the integrated master cylinder  1200  in a fallback mode will be described later with reference to  FIG. 6 . 
     The reservoir  1100  may accommodate and store the pressurized medium therein. The reservoir  1100  may be connected to each component such as the integrated master cylinder  1200 , the hydraulic pressure supply device  1300 , which will be described later, and the hydraulic circuits, which will be described later, to supply or receive the pressurized medium. Although a plurality of the reservoirs  1100  is shown with the same reference numeral in the drawings, this is only an example for better understanding of the present disclosure, and the reservoir  1100  may be provided as a single component, or a plurality of the separate and independent reservoirs  1100  may be provided. 
     The reservoir flow path  1700  is provided to connect the integrated master cylinder  1200  and the reservoir  1100 . 
     The reservoir flow path  1700  may include the first reservoir flow path  1710  connecting the master chamber  1220   a  and the reservoir  1100 , the second reservoir flow path  1720  connecting the first simulation chamber  1230   a  and the reservoir  1100 , and the third reservoir flow path  1730  connecting the second simulation chamber  1240   a  and the reservoir  1100 . To this end, one end of the first reservoir flow path  1710  may communicate with the master chamber  1220   a  of the integrated master cylinder  1200  and the other end thereof may communicate with the reservoir  1100 , one end of the second reservoir flow path  1720  may communicate with the first simulation chamber  1230   a  of the integrated master cylinder  1200  and the other end thereof may communicate with the reservoir  1100 , and one end of the third reservoir flow path  1730  may communicate with the second simulation chamber  1240   a  of the integrated master cylinder  1200  and the other end thereof may communicate with the reservoir  1100 . As shown in the drawing, the second reservoir flow path  1720  may be connected to the reservoir  1100  as the simulation flow path  1260  is branched from the second reservoir flow path  1720  and rejoins the second reservoir flow path  1720 , but is not limited thereto, and the second reservoir flow path  1720  and the simulation flow path  1260  may be connected to the reservoir  1100  independently of each other. 
     A reservoir valve  1721  for controlling a flow of a braking fluid transferred through the second reservoir flow path  1720  may be provided in the second reservoir flow path  1720 . The reservoir valve  1721  may be provided as a check valve allowing the flow of the pressurized medium directing to the first simulation chamber  1230   a  from the reservoir  1100  while blocking the flow of the pressurized medium directing to the reservoir  1100  from the first simulation chamber  1230   a.    
     The hydraulic pressure supply device  1300  is provided to receive an electrical signal corresponding to a pressing force of the driver from the pedal displacement sensor  11  detecting a displacement of the brake pedal  10  and to generate a hydraulic pressure of the pressurized medium through a mechanical operation. 
     The hydraulic pressure supply device  1300  may include a hydraulic pressure providing unit to provide a pressure to the pressurized medium to be transferred to the wheel cylinders  20 , a motor (not shown) to generate a rotational force by an electrical signal from the pedal displacement sensor  11 , and a power conversion unit (not shown) to convert a rotational motion of the motor into a linear motion to provide the linear motion to the hydraulic pressure providing unit. 
     The hydraulic pressure providing unit includes a cylinder block  1310  provided such that the pressurized medium may be accommodated, a hydraulic piston  1320  accommodated in the cylinder block  1310 , a sealing member  1350  provided between the hydraulic piston  1320  and the cylinder block  1310  to seal the pressure chambers  1330  and  1340 , and a drive shaft  1390  to transfer power output from the power conversion unit to the hydraulic piston  1320 . 
     The pressure chambers  1330  and  1340  may include the first pressure chamber  1330  located in the front of the hydraulic piston  1320  (left direction of the hydraulic piston  1320  in  FIG. 1 ), and the second pressure chamber  1340  located in the rear of the hydraulic piston  1320  (right direction of the hydraulic piston  1320  in  FIG. 1 ). That is, the first pressure chamber  1330  is provided to be partitioned by the cylinder block  1310  and a front surface of the hydraulic piston  1320  so that a volume thereof varies depending on the movement of the hydraulic piston  1320 , and the second pressure chamber  1340  is provided to be partitioned by the cylinder block  1310  and a rear surface of the hydraulic piston  1320  so that a volume thereof varies depending on the movement of the hydraulic piston  1320 . 
     The first pressure chamber  1330  is connected to a first hydraulic flow path  1401 , which will be described later, through a first communication hole  1360   a  formed on the cylinder block  1310 , and the second pressure chamber  1340  is connected to a second hydraulic flow path  1402 , which will be described later, through a second communication hole  1360   b  formed on the cylinder block  1310 . 
     The sealing members include a piston sealing member  1350   a  provided between the hydraulic piston  1320  and the cylinder block  1310  to seal between the first pressure chamber  1330  and the second pressure chamber  1340 , and a drive shaft sealing member  1350   b  provided between the drive shaft  1390  and the cylinder block  1310  to seal between the second pressure chamber  1340  and an opening of the cylinder block  1310 . The hydraulic pressure or negative pressure of the first pressure chamber  1330  and the second pressure chamber  1340  generated by the forward or backward movement of the hydraulic piston  1320  may not leak by being sealed by the piston sealing member  1350   a  and the drive shaft sealing member  1350   b  and may be transferred to the first hydraulic flow path  1401  and the second hydraulic flow path  1402 , which will be described later. 
     The motor (not shown) is provided to generate a driving force of the hydraulic piston  1320  by an electric signal output from the electronic control unit. The motor may include a stator and a rotor, and through this configuration, may provide power to generate a displacement of the hydraulic piston  1320  by rotating in a forward or reverse direction. A rotational angular speed and a rotational angle of the motor may be precisely controlled by a motor control sensor. Because the motor is a well-known technology, a detailed description thereof will be omitted. 
     The power conversion unit (not shown) is provided to convert a rotational force of the motor into a linear motion. The power conversion unit may be provided as a structure including, for example, a worm shaft (not shown), a worm wheel (not shown), and the drive shaft  1390 . 
     The worm shaft may be integrally formed with a rotation shaft of the motor and may rotate the worm wheel by a worm formed on an outer circumferential surface thereof to be engaged with the worm wheel. The worm wheel may linearly move the drive shaft  1390  by being connected to be engaged with the drive shaft  1390 , and the drive shaft  1390  is connected to the hydraulic piston  1320  so that the hydraulic piston  1320  may be slidably moved within the cylinder block  1310 . 
     Explaining the above operations again, when the displacement of the brake pedal  10  is detected by the pedal displacement sensor  11 , the detected signal is transferred to the electronic control unit, and the electronic control unit drives the motor to rotate the worm shaft in one direction. The rotational force of the worm shaft is transferred to the drive shaft  1390  via the worm wheel, and the hydraulic piston  1320  connected to the drive shaft  1390  moves forward in the cylinder block  1310 , thereby generating a hydraulic pressure in the first pressure chamber  1330 . 
     Conversely, when the pressing force of the brake pedal  10  is released, the electronic control unit drives the motor to rotate the worm shaft in the opposite direction. Accordingly, the worm wheel also rotates in the opposite direction, and the hydraulic piston  1320  connected to the drive shaft  1390  moves backward in the cylinder block  1310 , thereby generating a negative pressure in the first pressure chamber  1330 . 
     The generation of a hydraulic pressure and negative pressure in the second pressure chamber  1340  may be implemented by operating opposite to the above operations. That is, when the displacement of the brake pedal  10  is detected by the pedal displacement sensor  11 , the detected signal is transferred to the electronic control unit, and the electronic control unit drives the motor to rotate the worm shaft in the opposite direction. The rotational force of the worm shaft is transferred to the drive shaft  1390  via the worm wheel, and the hydraulic piston  1320  connected to the drive shaft  1390  moves backward within the cylinder block  1310 , thereby generating a hydraulic pressure in the second pressure chamber  1340 . 
     Conversely, when the pressing force of the brake pedal  10  is released, the electronic control unit drives the motor to rotate the worm shaft in one direction. Accordingly, the worm wheel also rotates in one direction, and the hydraulic piston  1320  connected to the drive shaft  1390  moves forward in the cylinder block  1310 , thereby generating a negative pressure in the second pressure chamber  1340 . 
     As such, the hydraulic pressure supply device  1300  may generate a hydraulic pressure or negative pressure in the first pressure chamber  1330  and the second pressure chamber  1340 , respectively, depending on the rotation direction of the worm shaft by the operation of the motor, and whether a hydraulic pressure is transferred to the chambers to perform braking, or whether a negative pressure is generated in the chambers to release braking may be determined by controlling the valves. A detailed description thereof will be given later. 
     The power conversion unit according to the present embodiment is not limited to any one structure as long as it may convert the rotational motion of the motor into the linear motion of the hydraulic piston  1320 , and may include devices having various structures and manners. 
     The hydraulic pressure supply device  1300  may be hydraulically connected to the reservoir  1100  by the dump controller  1800 . The dump controller  1800  may include a first dump flow path  1810  connecting the first pressure chamber  1330  and the reservoir  1100 , and a second dump flow path  1820  connecting the second pressure chamber  1340  and the reservoir  1100 . 
     A first dump check valve  1811  and a second dump check valve  1821  for controlling the flow of the pressurized medium may be provided in the first dump flow path  1810  and the second dump flow path  1820 , respectively. The first dump check valve  1811  may be provided to allow only the flow of the pressurized medium directing to the first pressure chamber  1330  from the reservoir  1100  and block the flow of the pressurized medium in the opposite direction, and the second dump check valve  1821  may be provided to allow only the flow of the pressurized medium directing to the second pressure chamber  1340  from the reservoir  1100  and block the flow of the pressurized medium in the opposite direction. 
     The hydraulic control unit  1400  may be provided to control a hydraulic pressure transferred to the respective wheel cylinders  20 , and the electronic control unit (ECU) is provided to control the hydraulic pressure supply device  1300  and various valves based on the hydraulic pressure information and pedal displacement information. 
     The hydraulic control unit  1400  may include the first hydraulic circuit  1510  for controlling the flow of the hydraulic pressure to be transferred to first and second wheel cylinders  21  and  22  among the four wheel cylinders  20 , and the second hydraulic circuit  1520  for controlling the flow of the hydraulic pressure to be transferred to third and fourth wheel cylinders  23  and  24 , and includes a plurality of flow paths and valves to control the hydraulic pressure to be transferred from the hydraulic pressure supply device  1300  to the wheel cylinders  20 . 
     The first hydraulic flow path  1401  is provided to be in communication with the first pressure chamber  1330 , and the second hydraulic flow path  1402  is provided to be in communication with the second pressure chamber  1340 . The first hydraulic flow path  1401  and the second hydraulic flow path  1402  may be provided to join in a third hydraulic flow path  1403 , and then may be formed to be branched into a fifth hydraulic flow path  1405  and a sixth hydraulic flow path  1406  to be respectively connected to the first hydraulic circuit  1510  and the second hydraulic circuit  1520 . 
     A first valve  1411  for controlling the flow of the pressurized medium may be provided in the first hydraulic flow path  1401 . The first valve  1411  may be provided as a check valve allowing only the flow of the pressurized medium directing to the third hydraulic flow path  1403  from the first pressure chamber  1330  and blocking the flow of the pressurized medium in the opposite direction. A second valve  1412  for controlling the flow of the pressurized medium is provided in the second hydraulic flow path  1402 , and the second valve  1412  may be provided as a bidirectional control valve for controlling the flow of the pressurized medium transferred along the second hydraulic flow path  1402 . The second valve  1412  may be provided as a normally closed type solenoid valve that operates to be opened when an electric signal is received from the electronic control unit in a normally closed state. The second valve  1412  may be controlled to be opened in a second braking mode and a third braking mode in the normal operation mode of the electronic brake system  1000 . A detailed description thereof will be given later with reference to  FIGS. 3 and 4 . 
     The first hydraulic flow path  1401  and the second hydraulic flow path  1402  may be joined to form the third hydraulic flow path  1403 , and the third hydraulic flow path  1403  is formed to be branched into a fourth hydraulic flow path  1404  connected to the first hydraulic circuit  1510  and the fifth hydraulic flow path  1405  connected to the second hydraulic circuit  1520 . 
     A third valve  1413  for controlling the flow of the pressurized medium may be provided in the fourth hydraulic flow path  1404 . The third valve  1413  may be provided as a check valve allowing only the flow of the pressurized medium directing to the first hydraulic circuit  1510  from the third hydraulic flow path  1403  and blocking the flow of the pressurized medium in the opposite direction. A fourth valve  1414  for controlling the flow of the pressurized medium may be provided in the fifth hydraulic flow path  1405 , and the fourth valve  1414  may be provided as a check valve allowing only the flow of the pressurized medium directing to the second hydraulic circuit  1520  from the third hydraulic flow path  1403  and blocking the flow of the pressurized medium in the opposite direction. 
     By the arrangement of the hydraulic flow paths and valves of the hydraulic control unit  1400  as described above, the hydraulic pressure generated in the first pressure chamber  1330  according to the forward movement of the hydraulic piston  1320  may be transferred to the first hydraulic circuit  1510  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 , and may be transferred to the second hydraulic circuit  1520  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . Also, the hydraulic pressure formed in the second pressure chamber  1340  according to the backward movement of the hydraulic piston  1320  may be transferred to the first hydraulic circuit  1510  by sequentially passing through the second hydraulic flow path  1402 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 , and may be transferred to the second hydraulic circuit  1520  by sequentially passing through the second hydraulic flow path  1402 , the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . 
     Conversely, a negative pressure may be generated in the first pressure chamber  1330  according to the backward movement of the hydraulic piston  1320 , and thus the pressurized medium may be supplied from the reservoir  1100  to the first pressure chamber  1330  through the first dump flow path  1810 . Also, a negative pressure may be generated in the second pressure chamber  1340  according to the forward movement of the hydraulic piston  1320 , and thus the pressurized medium may be supplied from the reservoir  1100  to the second pressure chamber  1340  through the second dump flow path  1820 . 
     A detailed description of the transfer of the hydraulic pressure and negative pressure by the arrangement of these hydraulic flow paths and valves will be given later with reference to  FIGS. 2 to 5 . 
     The first hydraulic circuit  1510  of the hydraulic control unit  1400  may control the hydraulic pressure in the first wheel cylinder  21  and the second wheel cylinder  22 , which are the two wheel cylinders  20  among the four wheels RR, RL, FR, and FL, and the second hydraulic circuit  1520  may control the hydraulic pressure in the third and fourth wheel cylinders  23  and  24  which are the other two wheel cylinders  20 . 
     The first hydraulic circuit  1510  receives the hydraulic pressure through the fourth hydraulic flow path  1404 , and the fourth hydraulic flow path  1404  may be formed to be branched into two flow paths connected to the first wheel cylinder  21  and the second wheel cylinder  22 . Also, the second hydraulic circuit  1520  receives the hydraulic pressure through the fifth hydraulic flow path  1405 , and the fifth hydraulic flow path  1405  may be formed to be branched into two flow paths connected to the third wheel cylinder  23  and the fourth wheel cylinder  242 . 
     The first and second hydraulic circuits  1510  and  1520  may include first to fourth inlet valves  1511   a,    1511   b,    1521   a,  and  1521   b,  respectively, to control the flow and hydraulic pressure of the pressurized medium to be transferred to the first to fourth wheel cylinders  21  to  24 . The first to fourth inlet valves  1511   a,    1511   b,    1521   a,  and  1521   b  are disposed on upstream sides of the first to fourth wheel cylinders  20 , respectively, and may be provided as a normally open type solenoid valve that operates to be closed when an electric signal is received from the electronic control unit in a normally open state. 
     The first and second hydraulic circuits  1510  and  1520  may include first to fourth check valves  1513   a,    1513   b,    1523   a,  and  1523   b  provided to be connected in parallel with respect to the first to fourth inlet valves  1511   a,    1511   b,    1521   a,  and  1521   b.  The check valves  1513   a,    1513   b,    1523   a,  and  1523   b  may be provided in bypass flow paths connecting front sides and rear sides of the first to fourth inlet valves  1511 a,  1511   b,    1521   a,  and  1521   b  on the first and second hydraulic circuits  1510  and  1520 , and may allow only the flow of pressurized medium from each of the wheel cylinders  20  to the hydraulic pressure supply device  1300  while blocking the flow of the pressurized medium from the hydraulic pressure supply device  1300  to the wheel cylinders  20 . By the first to fourth check valves  1513   a,    1513   b,    1523   a,  and  1523   b,  the hydraulic pressure of the pressurized medium applied to each of the wheel cylinders  20  may be quickly released, and even when the first to fourth inlet valves  1511   a,    1511   b,    1521   a,  and  1521   b  do not operate normally, the hydraulic pressure of the pressurized medium applied to the wheel cylinders  20  may be smoothly returned to the hydraulic pressure providing unit. 
     The first hydraulic circuit  1510  may include first and second outlet valves  1512   a  and  1512   b  for controlling the flow of the pressurized medium discharged from the first and second wheel cylinders  21  and  22  to improve performance when braking of the first and second wheel cylinders  21  and  22  is released. The first and second outlet valves  1512   a  and  1512   b  are provided on discharge sides of the first and second wheel cylinders  21  and  22 , respectively, to control the flow of the pressurized medium transferred from the first and second wheel cylinders  21  and  22  to a discharge valve  1550 , which will be described late. The first and second outlet valves  1512   a  and  1512   b  may be provided as normally open type solenoid valves that operate to be closed when an electric signal is received from the electronic control unit in a normally open state. 
     The discharge valve  1550  is provided to control the flow of the pressurized medium recovered from the first and second outlet valves  1512   a  and  1512   b  to the reservoir  1100 . To this end, the discharge valve  1550  may be provided between the first and second outlet valves  1512   a  and  1512   b  and the reservoir  1100 , is provided as a normally closed type valve that operates to be opened when an electric signal is received from the electronic control unit in a normally closed state, and may be provided as a solenoid valve in which an opening degree thereof is linearly adjustable to control a flow rate of the pressurized medium discharged from the first and second outlet valves  1512   a  and  1512   b  to the reservoir  1100 . The discharge valve  1550  may discharge the hydraulic pressure of the pressurized medium applied to the first and second wheel cylinders  21  and  22  to the reservoir  1100  side by adjusting the opening degree in the normal operation mode of the electromagnetic brake system  1000 , thereby performing a pressure reduction braking or a braking release. A release of the braking modes of the electromagnetic brake system  1000  by the discharge valve  1550  will be described later with reference to  FIG. 5 . 
     The second backup flow path  1620 , which will be described later, may be branched and connected to the third and fourth wheel cylinders  23  and  24  of the second hydraulic circuit  1520 , and the second cut valve  1621  may be provided in the second backup flow path  1620  to control the flow of the pressurized medium between the third and fourth wheel cylinders  23  and  24  and the integrated master cylinder  1200 . 
     The electronic brake system  1000  according to the present embodiment may include the first and second backup flow paths  1610  and  1620  and the auxiliary backup flow path  1630  to implement braking by directly supplying the pressurized medium discharged from the integrated master cylinder  1200  to the wheel cylinders  20  when the normal operation is impossible due to a device failure or the like. A mode in which the hydraulic pressure in the integrated master cylinder  1200  is directly transferred to the wheel cylinders  20  is referred to as an abnormal operation mode, that is, a fallback mode. 
     The first backup flow path  1610  may be provided to connect the master chamber  1220   a  of the integrated master cylinder  1200  and the first hydraulic circuit  1510 , and the second backup flow path  1620  may be provided to connect the first simulation chamber  1230   a  of the integrated master cylinder  1200  and the second hydraulic circuit  1520 . The auxiliary backup flow path  1630  is provided to connect the second simulation chamber  1240   a  of the integrated master cylinder  1200  and the second backup flow path  1620 . 
     Specifically, the first backup flow path  1610  may have one end connected to the master chamber  1220   a  and the other end connected between the first inlet valve  1511   a  and the first outlet valve  1512   a  on the first hydraulic circuit  1510 , and the second backup flow path  1620  may have one end connected to the first simulation chamber  1230   a  and the other end connected to downstream sides of the third and fourth inlet valves  1521   a  and  1521   b  on the second hydraulic circuit  1520 . Although  FIG. 1  illustrates that the first backup flow path  1610  is connected between the first inlet valve  1511   a  and the first outlet valve  1512   a,  the first backup flow path  1610  may be branched and connected to at least one of upstream sides of the first outlet valve  1512   a  and the second outlet valve  1512   b.  The auxiliary backup flow path  1630  has one end connected to the second simulation chamber  1240   a  and the other end provided to join the second backup flow path  1620 , so that the pressurized medium accommodated in the second simulation chamber  1240   a  may be transferred to the second backup flow path  1620 . 
     The first cut valve  1611  for controlling the bidirectional flows of the pressurized medium may be provided in the first backup flow path  1610 , and the at least one second cut valve  1621  for controlling the bidirectional flows of the pressurized medium may be provided in the second backup flow path  1620 . The first cut valve  1611  and the second cut valve  1621  may be provided as normally open type solenoid valves that operate to be closed when a closing signal is received from the electronic control unit in a normally open state. 
     An inspection valve  1631  for controlling the bidirectional flows of the pressurized medium is provided in the auxiliary backup flow path  1630 , and the inspection valve  1631  may be provided as a normally open type solenoid valve that operates to be closed when a closing signal is received from the electronic control unit in a normally open state. The inspection valve  1631  may be closed in the normal operation of the electronic brake system  1000  to seal the second simulation chamber  1240   a,  and may be closed in an inspection mode of inspecting whether a leak occurs in the integrated master cylinder  1200  or the simulator valve  1261 . A detailed description thereof will be given later. 
     Accordingly, when the first and second cut valves  1621  are closed, the pressurized medium in the integrated master cylinder  1200  may be prevented from being directly transferred to the wheel cylinders  20 , and at the same time the hydraulic pressure provided from the hydraulic pressure supply device  1300  may be supplied to the first and second hydraulic circuits  1510  and  1520  side through the hydraulic control unit  1400 , and when the first and second cut valves  1611  and  1612  and inspection valve  1631  are opened, the pressurized medium pressurized in the integrated master cylinder  1200  may be directly supplied to the first and second hydraulic circuits  1510  and  1520  side through the first and second backup flow paths  1620  and the auxiliary backup flow path  1630 , thereby performing braking. 
     The electronic brake system  1000  according to the present embodiment may include a pressure sensor PS to detect a hydraulic pressure in at least one of the first hydraulic circuit  1510  and the second hydraulic circuit  1520 . The drawing illustrates that the pressure sensor PS is provided in the second hydraulic circuit  1520  side, but the pressure sensor is not limited to the above position and number, and as long as the hydraulic pressures in the hydraulic circuits and the integrated master cylinder  1200  may be detected, the pressure sensor may be provided in various positions and in various numbers. 
     Hereinafter, operation methods of the electronic brake system  1000  according to the first embodiment of the present disclosure will be described. 
     The operation of the electronic brake system  1000  according to the present embodiment may include the normal operation mode in which various devices and valves operate normally without failure or malfunction, the abnormal operation mode (fallback mode) in which various devices and valves operate abnormally due to failure or malfunction, and the inspection mode of inspecting whether a leak occurs in the integrated master cylinder  1200  or the simulation valve  1261 . 
     First, the normal operation mode among the operating methods of the electronic brake system  1000  according to the present embodiment will be described. 
     The normal operation mode of the electronic brake system  1000  according to the present embodiment may be classified into a first braking mode, a second braking mode, and a third braking mode as the hydraulic pressure transferred from the hydraulic pressure supply device  1300  to the wheel cylinders  20  increases. Specifically, in the first braking mode, the hydraulic pressure may be firstly provided to the wheel cylinders  20  by the hydraulic pressure supply device  1300 , in the second braking mode, the hydraulic pressure may be secondarily provided to the wheel cylinders  20  by the hydraulic pressure supply device  1300  to transfer a higher braking pressure than in the first braking mode, and in the third braking mode, the hydraulic pressure may be thirdly provided to the wheel cylinders  20  by the hydraulic pressure supply device  1300  to transfer a higher braking pressure than in the second braking mode. 
     The first to third braking modes may be changed by varying the operations of the hydraulic pressure supply device  1300  and the hydraulic control unit  1400 . The hydraulic pressure supply device  1300  may provide a sufficiently high hydraulic pressure of the pressurized medium without a high specification motor by utilizing the first to third braking modes, and furthermore, may prevent unnecessary loads applied to the motor. Therefore, a stable braking force may be secured while reducing the cost and weight of the brake system, and durability and operational reliability of the devices may be improved. 
       FIG. 2  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the present embodiment performs the first braking mode. 
     Referring to  FIG. 2 , when the driver depresses the brake pedal  10  at a beginning of braking, the motor (not shown) operates to rotate in one direction, the rotational force of the motor is transferred to the hydraulic pressure providing unit by the power conversion unit, and the hydraulic piston  1320  of the hydraulic pressure providing unit moves forward, thereby generating a hydraulic pressure in the first pressure chamber  1330 . The hydraulic pressure discharged from the first pressure chamber  1330  is transferred to the respective wheel cylinders  20  through the hydraulic control unit  1400 , the first hydraulic circuit  1510  and the second hydraulic circuit  1520 , thereby generating a braking force. 
     Specifically, the hydraulic pressure generated in the first pressure chamber  1330  is primarily transferred to the first wheel cylinder  21  and the second wheel cylinder  22  provided in the first hydraulic circuit  1510  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 . At this time, as the first valve  1411  and the third valve  1413  are provided as check valves allowing only the flow of the pressurized medium directing to the first hydraulic circuit  1510  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the first and second wheel cylinders  21  and  22 . Also, the first inlet valve  1511   a  and the second inlet valve  1511   b  provided in the first hydraulic circuit  1510  are maintained in an open state, and the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550  are controlled to be closed, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the reservoir  1100  side. 
     Also, the hydraulic pressure of the pressurized medium generated in the first pressure chamber  1330  is primarily transferred to the third and fourth wheel cylinders  23  and  24  provided in the second hydraulic circuit  1520  by sequentially passing through the first hydraulic flow path  1401 , and the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . As described above, as the first valve  1411  and the fourth valve  1414  are provided as check valves allowing only the flow of the pressurized medium directing to the second hydraulic circuit  1520  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the third and fourth wheel cylinders  23  and  24 . Also, the third inlet valve  1521   a  and the fourth inlet valve  1521   b  provided in the second hydraulic circuit  1520  are maintained in an open state, and a second cut valve  1622  is maintained in a closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the second backup flow path  1620  side. 
     In the first braking mode, as the second dump check valve  1821  provided in the second dump flow path  1820  connected to the second pressure chamber  1340  allows the pressurized medium to be supplied from the reservoir  1100  to the second pressure chamber  1340 , the second pressure chamber  1340  may be filled with the pressurized medium, thereby preparing the second braking mode, which will be described later. 
     In the first braking mode in which braking of the wheel cylinders  20  is performed by the hydraulic pressure supply device  1300 , the first cut valve  1611  and the second cut valve  1621  provided in the first backup flow path  1610  and the second backup flow path  1620 , respectively, are switched to be closed, so that the pressurized medium discharged from the integrated master cylinder  1200  is prevented from being transferred to the wheel cylinders  20  side. 
     Specifically, because the first cut valve  1611  is closed when a pressing force is applied to the brake pedal  10 , the master chamber  1220   a  is sealed. Therefore, as the pressing force is applied to the brake pedal  10 , the pressurized medium accommodated in the master chamber  1220   a  is pressurized to generate a hydraulic pressure, the hydraulic pressure of the pressurized medium generated in the master chamber  1220   a  is transferred to the front surface (right side of  FIG. 2 ) of the first simulation piston  1230 , and the simulator valve  1261  is opened in the normal operation mode, so that a displacement is generated in the first simulation piston  1230 . On the other hand, because the inspection valve  1631  is closed in the normal operation mode of the electronic brake system  1000 , the second simulation chamber  1240   a  is sealed so that a displacement is not generated in the second simulation piston  1240 , and thus the elastic member  1250  is compressed by the displacement of the first simulation piston  1230 , and the elastic restoring force by the compression of the elastic member  1250  is provided to the driver as a pedal feeling. At this time, the pressurized medium accommodated in the first simulation chamber  1230   a  is discharged to the reservoir  1100  through the simulation flow path  1260 . 
     The electronic brake system  1000  according to the present embodiment may switch from the first braking mode to the second braking mode illustrated in  FIG. 3  when a braking pressure higher than that in the first braking mode is to be provided. 
       FIG. 3  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the present embodiment performs the second braking mode, and referring to  FIG. 3 , when a displacement or an operating speed of the brake pedal  10  detected by the pedal displacement sensor  11  is higher than a preset level or a hydraulic pressure detected by the pressure sensor is higher than a preset level, the electronic control unit may switch from the first braking mode to the second braking mode by determining that a higher braking pressure is required. 
     When the first braking mode is switched to the second braking mode, the motor operates to rotate in the other direction, and the rotational force of the motor is transferred to the hydraulic pressure providing unit by the power conversion unit so that the hydraulic piston  1320  moves backward, thereby generating a hydraulic pressure in the second pressure chamber  1340 . The hydraulic pressure discharged from the second pressure chamber  1340  is transferred to the respective wheel cylinders  20  through the hydraulic control unit  1400 , the first hydraulic circuit  1510 , and the second hydraulic circuit  1520 , thereby generating a braking force. 
     Specifically, the hydraulic pressure generated in the second pressure chamber  1340  is secondarily transferred to the first wheel cylinder  21  and the second wheel cylinder  22  provided in the first hydraulic circuit  1510  by sequentially passing through the second hydraulic flow path  1402 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 . At this time, as the second valve  1412  provided in the second hydraulic flow path  1402  is opened, the flow of the pressurized medium transferred along the second hydraulic flow path  1402  toward the third hydraulic flow path  1403  may be stably provided. The first inlet valve  1511   a  and the second inlet valve  1511   b  provided in the first hydraulic circuit  1510  are maintained in the open state, and the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550  are closed, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the reservoir  1100  side. 
     Also, the hydraulic pressure generated in the second pressure chamber  1340  is secondarily transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24  provided in the second hydraulic circuit  1520  by sequentially passing through the second hydraulic flow path  1402 , the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . 
     As the fourth valve  1414  provided in the fifth hydraulic flow path  1405  is provided as a check valve allowing only the flow of the pressurized medium directing to the second hydraulic circuit  1520  side from the second pressure chamber  1340 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24 . The third inlet valve  1521   a  and the fourth inlet valve  1521   b  provided in the second hydraulic circuit  1520  are maintained in the open state, and the second cut valve  1622  is maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the second backup flow path  1620  side. 
     In the second braking mode, as the first valve  1411  provided in the first hydraulic flow path  1401  is provided as a check valve blocking the flow of the pressurized medium directing to the first pressure chamber  1330 , the hydraulic pressure of the pressurizing medium generated in the second pressure chamber  1340  may be prevented from being transferred to the first pressure chamber  1330 . Also, as the first dump check valve  1811  provided in the first dump flow path  1810  connected to the first pressure chamber  1330  allows the pressurized medium to be supplied from the reservoir  1100  to the first pressure chamber  1330 , the first pressure chamber  1330  may be filled with the pressurized medium, thereby preparing the third braking mode, which will be described later. 
     Because an operation of the integrated master cylinder  1200  in the second braking mode is the same as the operation of the integrated master cylinder  1200  in the first braking mode described above, a description thereof will be omitted to prevent duplication of contents. 
     The electronic brake system  1000  according to the present embodiment may switch from the second braking mode to the third braking mode illustrated in  FIG. 4  when a braking pressure higher than that in the second braking mode is to be provided. 
       FIG. 4  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the present embodiment performs the third braking mode. 
     Referring to  FIG. 4 , when a displacement or an operating speed of the brake pedal  10  detected by the pedal displacement sensor  11  is higher than a preset level or a hydraulic pressure detected by the pressure sensor is higher than a preset level, the electronic control unit may switch from the second braking mode to the third braking mode by determining that a higher braking pressure is required. 
     When the second braking mode is switched to the third braking mode, the motor (not shown) operates to rotate in one direction, and the rotational force of the motor is transferred to the hydraulic pressure providing unit by the power conversion unit so that the hydraulic piston  1320  of the hydraulic pressure providing unit moves forward again, thereby generating a hydraulic pressure in the first pressure chamber  1330 . The hydraulic pressure discharged from the first pressure chamber  1330  is transferred to the respective wheel cylinders  20  through the hydraulic control unit  1400 , the first hydraulic circuit  1510 , and the second hydraulic circuit  1520 , thereby generating a braking force. 
     Specifically, the hydraulic pressure generated in the first pressure chamber  1330  is thirdly transferred to the first wheel cylinder  21  and the second wheel cylinder  22  provided in the first hydraulic circuit  1510  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 . At this time, as the first valve  1411  and the third valve  1413  are provided as check valves allowing only the flow of the pressurized medium directing to the first hydraulic circuit  1510  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the first and second wheel cylinders  21  and  22 . Also, the first inlet valve  1511   a  and the second inlet valve  1511   b  provided in the first hydraulic circuit  1510  are maintained in the open state, and the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550  are maintained in a closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the reservoir  1100  side. 
     Also, the hydraulic pressure of the pressurized medium generated in the first pressure chamber  1330  is thirdly transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24  provided in the second hydraulic circuit  1520  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . As described above, as the first valve  1411  and the fourth valve  1414  are provided as check valves allowing only the flow of the pressurized medium directing to the second hydraulic circuit  1520  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24 . The third inlet valve  1521   a  and the fourth inlet valve  1521   b  provided in the second hydraulic circuit  1520  are maintained in the open state, and the second cut valve  1622  is maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the second backup flow path  1620  side. 
     Because the hydraulic pressure of a high pressure is provided in the third braking mode, as the hydraulic piston  1320  moves forward, a force of the hydraulic pressure in the first pressure chamber  1330  to move the hydraulic piston  1320  backward also increases, so that a load applied to the motor increases rapidly. Accordingly, in the third braking mode, the second valve  1412  is operated to open, thereby allowing the flow of the pressurized medium through the second hydraulic flow path  1402 . In other words, a part of the hydraulic pressure generated in the first pressure chamber  1330  may be supplied to the second pressure chamber  1340  by sequentially passing through the first hydraulic flow path  1401  and the second flow path  1402 , and through this, the first pressure chamber  1330  and the second pressure chamber  1340  are in communication with each other to synchronize the hydraulic pressure, so that the load applied to the motor may be reduced and the durability and reliability of the devices may be improved. 
     Because an operation of the integrated master cylinder  1200  in the third braking mode is the same as the operation of the integrated master cylinder  1200  in the first braking mode described above, a description thereof will be omitted to prevent duplication of contents. 
     Hereinafter, an operation method of releasing the braking in the normal operation mode of the electronic brake system  1000  according to the present embodiment will be described. 
       FIG. 5  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the present embodiment releases the braking. 
     Referring to  FIG. 5 , when the pressing force applied to the brake pedal  10  is released, the motor generates a rotational force in any one direction and transmits the rotational force to the power conversion unit, and the power conversion unit returns the hydraulic piston  1320  to an original position thereof. As the hydraulic piston  1320  moves forward or backward to return to the original position, the hydraulic pressure generated in the first pressure chamber  1330  or the second pressure chamber  1340  may be transferred to the first hydraulic circuit  1510  or the second hydraulic circuit  1520  through the hydraulic control unit  1400  to be discharged to the reservoir  1100  side together with the hydraulic pressure of the pressurizing medium applied to the wheel cylinders  20 . 
     Specifically, the hydraulic pressure of the pressurized medium applied to the first wheel cylinder  21  and the second wheel cylinder  22  provided in the first hydraulic circuit  1510  may be discharged to the reservoir  1100  by sequentially passing through the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550 . To this end, the first and second outlet valves  1512   a  and  1512   b  may be switched to an open state, and the discharge valve  1550  may adjust the flow rate of the pressurized medium to be discharged to the reservoir  1100  by adjusting the opening degree depending on a displacement amount of the brake pedal  10 , thereby performing the pressure reduction braking or the braking release. At this time, as described above, the first inlet valve  1511   a  and the second inlet valve  1511   b  may be maintained in the open state so that the hydraulic pressure generated in the first pressure chamber  1330  or the second pressure chamber  1340  by the return of the hydraulic piston  1320  to the original position may also be discharged to the reservoir  1100  by sequentially passing through the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550 . 
     Also, the hydraulic pressure of the pressurized medium applied to the third wheel cylinder  23  and the fourth wheel cylinder  24  provided in the second hydraulic circuit  1520  may be discharged to the reservoir  1100  by sequentially passing through the second backup flow path  1620 , the first simulation chamber  1230   a,  and the simulation flow path  1260 . To this end, the second cut valve  1621  and the simulator valve  1261  may be switched to an open state, and at least one of the second cut valve  1621  and in response to a degree of pressure reduction of the hydraulic pressure applied to the first hydraulic circuit  1510  being adjusted by the discharge valve  1550 , the simulator valve  1261  may be provided as a solenoid valve that is linearly controlled to adjust the flow rate of the pressurized medium passing therethrough, like the discharge valve  1550 . At this time, as described above, the third inlet valve  1521   a  and the fourth inlet valve  152  lb may be maintained in the open state so that the hydraulic pressure generated in the first pressure chamber  1330  or the second pressure chamber  1340  by the return of the hydraulic piston  1320  to the original position may also be discharged to the reservoir  1100  by sequentially passing through the second backup flow path  1620 , the first simulation chamber  1230   a,  and the simulation flow path  1260 . Hereinafter, the case in which the electronic brake system  1000  according to the present embodiment does not operate normally, that is, operates in the fallback mode will be described. 
       FIG. 6  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the present embodiment operates in the case in which the normal operation is impossible due to a device failure or the like, that is, in the case of the abnormal operation mode (fallback mode). 
     Referring to  FIG. 6 , in the abnormal operation mode, each of the valves is controlled to an initial braking state which is a non-operational state. At this time, when the driver depresses the brake pedal  10 , the master piston  1220  connected to the brake pedal  10  moves forward to generate a displacement. Because the first cut valve  1611  is provided in the open state in the non-operational state, by the forward movement of the master piston  1220 , the pressurized medium accommodated in the master chamber  1220   a  is transferred to the first wheel cylinder  21  and the second wheel cylinder  22  of the first hydraulic circuit  1510  along the first backup flow path  1610 , thereby performing braking. 
     Also, the pressurized medium accommodated in the master chamber  1220 a moves the first simulation piston  1230  forward to generate a displacement, so that the pressurized medium accommodated in the first simulation chamber  1230   a  is transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24  of the second hydraulic circuit  1520  along the second backup flow path  1620 , thereby performing braking. At the same time, the second simulation piston  1240  also generates a displacement by moving forward due to the displacement of the first simulation piston  1230 , so that the pressurized medium accommodated in the second simulation chamber  1240   a  may be provided to the second hydraulic circuit  1520  by joining into the second backup flow path  1620  along the auxiliary backup flow path  1630 . At this time, because the simulator valve  1261  is provided in a closed state in the non-operational state, the pressurized medium accommodated in the first simulation chamber  1230   a  may be transferred to the second backup flow path  1620  without being discharged to the reservoir  1100 , and at the same time, may generate a hydraulic pressure for moving the second simulation piston  1240  forward, and because the inspection valve  1631  and the second cut valve  1621  are provided in an open state, the pressurized medium accommodated in the first simulation chamber  1230   a  and the second simulation chamber  1240   a  may be transferred to the second backup flow path  1620 . 
     Hereinafter, the inspection mode of the electronic brake system  1000  according to the present embodiment will be described. 
       FIG. 7  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the present embodiment performs the inspection mode, and referring to  FIG. 7 , the electronic brake system  1000  according to the present embodiment may perform the inspection mode of inspecting whether a leak is generated in the integrated master cylinder  1200  or the simulator valve  1261 . When the inspection mode is performed, the electronic control unit controls to supply the hydraulic pressure generated from the hydraulic pressure supply device  1300  to the first simulation chamber  1230   a  of the integrated master cylinder  1200 . 
     Specifically, in a state in which each of the valves is controlled to the initial braking state, which is the non-operational state, the electronic control unit operates to move the hydraulic piston  1320  forward, so that a hydraulic pressure is generated in the first pressure chamber  1330 , the inspection valve  1631  and the first cut valve  1611  are switched to a closed state, and the second cut valve  1621  is maintained in the open state. Accordingly, as the hydraulic pressure generated in the first pressure chamber  1330  is transferred to the second hydraulic circuit  1520  side by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 , and the third inlet valve  1521   a  and the fourth inlet valve  1521   b  are maintained in a normally open state, the pressurized medium transferred to the second hydraulic circuit  1520  is introduced into the first simulation chamber  1230 a through the second backup flow path  1620 . At this time, the simulator valve  1261  is maintained in the closed state to induce the first simulation chamber  1230   a  to be in a sealed state. 
     In this state, by comparing an expected hydraulic pressure value of the pressurized medium to be generated by the displacement of the hydraulic piston  1320  with a hydraulic pressure value in the second hydraulic circuit  1520  or the first simulation chamber  1230   a  measured by the pressure sensor PS, a leak in the integrated master cylinder  1200  or the simulator valve  1261  may be diagnosed. Specifically, the expected hydraulic pressure value calculated based on a displacement amount of the hydraulic piston  1320  or a rotational angle measured by a motor control sensor (not shown) is compared with an actual hydraulic pressure value measured by the pressure sensor PS, and when the two hydraulic pressure values match, it may be determined that there is no leak in the integrated master cylinder  1200  or the simulator valve  1261 . On the other hand, when the actual hydraulic pressure value measured by the pressure sensor PS is lower than the expected hydraulic pressure value calculated based on the displacement amount of the hydraulic piston  1320  or the rotational angle measured by the motor control sensor (not shown), this is due to the loss of a part of the hydraulic pressure of the pressurized medium applied to the first simulation chamber  1230   a,  and thus it may be determined that there is a leak in the integrated master cylinder  1200  or the simulator valve  1261 , and this leak may be notified to the driver. 
     Hereinafter, an electronic brake system  2000  according to a second embodiment of the present disclosure will be described. 
       FIG. 8  is a hydraulic circuit diagram illustrating the electronic brake system  2000  according to the second embodiment of the present disclosure, and referring to  FIG. 8 , a fourth valve  2414  of a hydraulic control unit  2400  according to the second embodiment of the present disclosure is provided to perform cooperative control for a regenerative braking mode. 
     Because the following description of the electronic brake system  2000  according to the second embodiment of the present disclosure except for additional explanation with separate reference numerals is the same as the above description of the electronic brake system  1000  according to the first embodiment of the present disclosure, a description thereof will be omitted in order to prevent redundant description. 
     Recently, as the market demand for eco-friendly vehicles increases, hybrid vehicles with improved fuel efficiency are gaining popularity. The hybrid vehicle recovers kinetic energy as electric energy while braking the vehicle, stores the electric energy in a battery, and then utilizes the motor as an auxiliary driving source of the vehicle, and the hybrid vehicle typically recovers energy by a generator (not shown) or the like during a braking operation of the vehicle in order to increase the energy recovery rate. This braking operation is referred to as a regenerative braking mode, and in the electronic brake system  2000  according to the present embodiment, a generator (not shown) may be provided in the third wheel cylinder  23  and the fourth wheel cylinder  24  of the second hydraulic circuit  1520  to implement the regenerative braking mode. The generator and the fourth valve  2414  in the third and fourth wheel cylinders  23  and  24  may perform the regenerative braking mode through cooperative control. 
     The fourth valve  2414  provided in the fifth hydraulic flow path  1405  may be provided as a bidirectional control valve for controlling the flow of the pressurized medium transferred along the fifth hydraulic flow path  1405 . The fourth valve  2414  may be provided as a normally closed type solenoid valve that operates to be opened when an electric signal is received from the electronic control unit in a normally closed state. The fourth valve  2414  is controlled to be opened in a normal operation mode of the electronic brake system  2000 , and may be switched to a closed state when entering the regenerative braking mode by the generator (not shown) provided in the third wheel cylinder  23  and the fourth wheel cylinder  24 . 
     Hereinafter, the regenerative braking mode of the electronic brake system  2000  according to the second embodiment of the present disclosure will be described. 
       FIG. 9  is a hydraulic circuit diagram illustrating that the electronic brake system  2000  according to the second embodiment of the present disclosure performs the regenerative braking mode, and referring to  FIG. 9 , while in the case of the first wheel cylinder  21  and the second wheel cylinder  22  of the first hydraulic circuit  1510 , a braking force that the driver intends to implement is only generated by the hydraulic pressure of the pressurized medium by the operation of the hydraulic pressure supply device  1300 , in the case of the third wheel cylinder  23  and the fourth wheel cylinder  24  of the second hydraulic circuit  1520  in which an energy recovery device such as a generator is installed, the sum of the braking pressure of the pressurized medium by the hydraulic pressure supply device  1300  and the total braking pressure plus the regenerative braking pressure by the generator should be equal to the total braking force of the first wheel cylinder  21  and the second wheel cylinder  22 . 
     Therefore, when entering the regenerative braking mode, as the braking pressure by the hydraulic pressure supply device  1300  applied to the third wheel cylinder  23  and the fourth wheel cylinder  24  is removed or maintained constant by closing the fourth valve  2414 , and at the same time the regenerative braking pressure by the generator is increased, the total braking force of the third and fourth wheel cylinders  23  and  24  may be equal to the braking force of the first and second wheel cylinders  21  and  22 . 
     Specifically, when the driver depresses the brake pedal  10  to brake the vehicle, the motor (not shown) operates to rotate in one direction, the rotational force of the motor is transferred to the hydraulic pressure providing unit by the power conversion unit, and the hydraulic piston  1320  of the hydraulic pressure providing unit moves forward, thereby generating a hydraulic pressure in the first pressure chamber  1330 . The hydraulic pressure discharged from the first pressure chamber  1330  is transferred to the respective wheel cylinders  20  through the hydraulic control unit  1400 , the first hydraulic circuit  1510  and the second hydraulic circuit  1520 , thereby generating a braking force. 
     In the case of the first hydraulic circuit  1510  in which an energy recovery device such as a generator is not installed, the hydraulic pressure of the pressurized medium generated in the first pressure chamber  1330  sequentially passes through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 , and is transferred to the first and second wheel cylinders  21  and  22 , thereby performing braking. As described above, as the first valve  1411  and the third valve  1413  allow the flow of the pressurized medium directing to the first hydraulic circuit  1510  from the first pressure chamber  1330 , the hydraulic pressure of the pressurizing medium generated in the first pressure chamber  1330  may be transferred to the first hydraulic circuit  1510 . 
     On the other hand, in the case of the second hydraulic circuit  1520  in which the generator is installed, when the electronic control unit determines that it is possible to enter the regenerative braking mode by sensing a speed, deceleration, etc. of the vehicle, the electronic control unit may close the fourth valve  2414  to block transmission of the hydraulic pressure of the pressurized medium to the third wheel cylinder  23  and the fourth wheel cylinder  24 , and may implement regenerative braking by the generator. Thereafter, when the electronic control unit determines that the vehicle is in an unsuitable state for regenerative braking, or the braking pressure in the first hydraulic circuit  1510  and the braking pressure in the second hydraulic circuit  1520  are different, the electronic control unit may control the hydraulic pressure of the pressurizing medium to be transferred to the second hydraulic circuit  1520  by switching the fourth valve  2414  to an open state, and the at the same time may synchronize the braking pressure in the first hydraulic circuit  1510  and the braking pressure in the second hydraulic circuit  1520 . Accordingly, the braking pressure or braking force applied to the first to fourth wheel cylinders  20  may be uniformly controlled, so that in addition to braking stability of the vehicle, oversteering or understeering may be prevented to improve driving stability of the vehicle. 
     Hereinafter, an electronic brake system  3000  according to a third embodiment of the present disclosure will be described. 
       FIG. 10  is a hydraulic circuit diagram illustrating the electronic brake system  3000  according to the third embodiment of the present disclosure, and referring to  FIG. 10 , a hydraulic control unit  3400  according to the third embodiment of the present disclosure may be provided to further include a sixth hydraulic flow path  3406  connecting the first hydraulic flow path  1401  and the second hydraulic flow path  1402 , and a fifth valve  3415  provided in the sixth hydraulic flow path  3406  to control the flow of the pressurized medium, and a second valve  3412  provided in the second hydraulic flow path  1402  may be provided as a check valve allowing only the flow of the pressurized medium discharged from the second pressure chamber  1340 . 
     Because the following description of the electronic brake system  3000  according to the third embodiment of the present disclosure except for additional explanation with separate reference numerals is the same as the above description of the electronic brake system  1000  according to the first embodiment of the present disclosure, a description thereof will be omitted in order to prevent redundant description. 
     The second valve  3412  provided in the second hydraulic flow path  1402  may be provided as a check valve allowing only the flow of the pressurized medium directing to the third hydraulic flow path  1403  from the second pressure chamber  1340  and blocking the flow of the pressurized medium in the opposite direction. 
     The sixth hydraulic flow path  3406  is provided to connect the first hydraulic flow path  1401  and the second hydraulic flow path  1402 . Specifically, one end of the sixth hydraulic flow path  3406  may be connected between the first pressure chamber  1330  and the first valve  1411  on the first hydraulic flow path  1401 , and the other end thereof may be connected between the second pressure chamber  1340  and the second valve  3412  on the second hydraulic flow path  1402 . The fifth valve  3415  is provided in the sixth hydraulic flow path  3406  to control the flow of the pressurized medium, and may be provided as a bidirectional control valve for controlling the flow of the pressurized medium transferred along the second hydraulic flow path  1402 . The fifth valve  3415  may be provided as a normally closed type solenoid valve that operates to be opened when an electric signal is received from the electronic control unit in a normally closed state. The fifth valve  3415  may be controlled to be opened in a third braking mode of a normal operation mode of the electronic brake system  3000 . A detailed description thereof will be given later with reference to  FIG. 13 . 
     Hereinafter, an operation method of the electronic brake system  3000  according to the third embodiment of the present disclosure will be described. 
     The normal operation mode of the electronic brake system  3000  according to the third embodiment of the present disclosure may be classified into a first braking mode, a second braking mode, and the third braking mode as the hydraulic pressure transferred from the hydraulic pressure supply device  1300  to the wheel cylinders  20  increases. Specifically, in the first braking mode, the hydraulic pressure may be firstly provided to the wheel cylinders  20  by the hydraulic pressure supply device  1300 , in the second braking mode, the hydraulic pressure may be secondarily provided to the wheel cylinders  20  by the hydraulic pressure supply device  1300  to transfer a higher braking pressure than in the first braking mode, and in the third braking mode, the hydraulic pressure may be thirdly provided to the wheel cylinders  20  by the hydraulic pressure supply device  1300  to transfer a higher braking pressure than in the second braking mode. 
     The first to third braking modes may be changed by varying the operations of the hydraulic pressure supply device  1300  and the hydraulic control unit  3400 . The hydraulic pressure supply device  1300  may provide a sufficiently high hydraulic pressure of the pressurized medium without a high specification motor by utilizing the first to third braking modes, and furthermore, may prevent unnecessary loads applied to the motor. Therefore, a stable braking force may be secured while reducing the cost and weight of the brake system, and durability and operational reliability of the devices may be improved. 
       FIG. 11  is a hydraulic circuit diagram illustrating that the electronic brake system  3000  according to the third embodiment of the present disclosure performs the first braking mode. 
     Referring to  FIG. 11 , when the driver depresses the brake pedal  10  at the beginning of braking, the motor (not shown) operates to rotate in one direction, the rotational force of the motor is transferred to the hydraulic pressure providing unit by the power conversion unit, and the hydraulic piston  1320  of the hydraulic pressure providing unit moves forward, thereby generating a hydraulic pressure in the first pressure chamber  1330 . The hydraulic pressure discharged from the first pressure chamber  1330  is transferred to the respective wheel cylinders  20  through the hydraulic control unit  1400 , the first hydraulic circuit  1510  and the second hydraulic circuit  1520 , thereby generating a braking force. 
     Specifically, the hydraulic pressure generated in the first pressure chamber  1330  is primarily transferred to the first wheel cylinder  21  and the second wheel cylinder  22  provided in the first hydraulic circuit  1510  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 . At this time, the fifth valve  3415  is maintained in a closed state to prevent the hydraulic pressure generated in the first pressure chamber  1330  from leaking into the second pressure chamber  1340  along the sixth hydraulic flow path  3406 . Also, as the first valve  1411  and the third valve  1413  are provided as check valves allowing only the flow of the pressurized medium directing to the first hydraulic circuit  1510  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the first and second wheel cylinders  21  and  22 . The first inlet valve  1511   a  and the second inlet valve  1511 b provided in the first hydraulic circuit  1510  are maintained in the open state, and the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550  are maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the reservoir  1100  side. 
     The hydraulic pressure of the pressurized medium generated in the first pressure chamber  1330  is primarily transferred to the third and fourth wheel cylinders  23  and  24  provided in the second hydraulic circuit  1520  by sequentially passing through the first hydraulic flow path  1401 , and the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . As described above, the fifth valve  3415  is maintained in the closed state to prevent the hydraulic pressure generated in the first pressure chamber  1330  from leaking into the second pressure chamber  1340  side along the sixth hydraulic flow path  3406 , and as the first valve  1411  and the fourth valve  1414  are provided as check valves allowing only the flow of the pressurized medium directing to the second hydraulic circuit  1520  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the third and fourth wheel cylinders  23  and  24 . The third inlet valve  1521   a  and the fourth inlet valve  1521   b  provided in the second hydraulic circuit  1520  are maintained in the open state, and the second cut valve  1622  is maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the second backup flow path  1620  side. 
     In the first braking mode, as the second dump check valve  1821  provided in the second dump flow path  1820  connected to the second pressure chamber  1340  allows the pressurized medium to be supplied from the reservoir  1100  to the second pressure chamber  1340 , the second pressure chamber  1340  may be filled with the pressurized medium, thereby preparing the second braking mode, which will be described later. 
     Because an operation of the integrated master cylinder  1200  in the first braking mode is the same as the operation of the integrated master cylinder  1200  in the first to third braking modes of the electronic brake system according to the first embodiment described above, a description thereof will be omitted to prevent duplication of contents. 
     The electronic brake system  3000  according to the third embodiment of the present disclosure may switch from the first braking mode to the second braking mode illustrated in  FIG. 12  when a braking pressure higher than that in the first braking mode is to be provided. 
       FIG. 12  is a hydraulic circuit diagram illustrating that the electronic brake system  3000  according to the third embodiment of the present disclosure performs the second braking mode, and referring to  FIG. 12 , when a displacement or an operating speed of the brake pedal  10  detected by the pedal displacement sensor  11  is higher than a preset level or a hydraulic pressure detected by the pressure sensor is higher than a preset level, the electronic control unit may switch from the first braking mode to the second braking mode by determining that a higher braking pressure is required. 
     When the first braking mode is switched to the second braking mode, the motor operates to rotate in the other direction, and the rotational force of the motor is transferred to the hydraulic pressure providing unit by the power conversion unit so that the hydraulic piston  1320  moves backward, thereby generating a hydraulic pressure in the second pressure chamber  1340 . The hydraulic pressure discharged from the second pressure chamber  1340  is transferred to the respective wheel cylinders  20  through the hydraulic control unit  1400 , the first hydraulic circuit  1510 , and the second hydraulic circuit  1520 , thereby generating a braking force. 
     Specifically, the hydraulic pressure generated in the second pressure chamber  1340  is secondarily transferred to the first wheel cylinder  21  and the second wheel cylinder  22  provided in the first hydraulic circuit  1510  by sequentially passing through the second hydraulic flow path  1402 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 . At this time, the fifth valve  3415  is maintained in the closed state to prevent the hydraulic pressure generated in the second pressure chamber  1340  from leaking into the first pressure chamber  1330  side along the sixth hydraulic flow path  3406 . Also, as the second valve  3412  and the third valve  1413  are provided as check valves allowing only the flow of the pressurized medium directing to the first hydraulic circuit  1510  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the first and second wheel cylinders  21  and  22 . The first inlet valve  1511   a  and the second inlet valve  1511 b provided in the first hydraulic circuit  1510  are maintained in the open state, and the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550  are maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the reservoir  1100  side. 
     Also, the hydraulic pressure generated in the second pressure chamber  1340  is secondarily transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24  provided in the second hydraulic circuit  1520  by sequentially passing through the second hydraulic flow path  1402 , the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . At this time, as described above, the fifth valve  3415  is maintained in the closed state to prevent the hydraulic pressure generated in the second pressure chamber  1340  from leaking into the first pressure chamber  1330  side along the sixth hydraulic flow path  3406 , and as the fourth valve  1414  provided in the fifth hydraulic flow path  1405  is provided as check valves allowing only the flow of the pressurized medium directing to the second hydraulic circuit  1520  side from the second pressure chamber  1340 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24 . The third inlet valve  1521   a  and the fourth inlet valve  152  lb provided in the second hydraulic circuit  1520  are maintained in the open state, and the second cut valve  1622  is maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the second backup flow path  1620  side. 
     In the second braking mode, as the first dump check valve  1811  provided in the first dump flow path  1810  connected to the first pressure chamber  1330  allows the pressurized medium to be supplied from the reservoir  1100  to the first pressure chamber  1330 , the first pressure chamber  1330  may be filled with the pressurized medium, thereby preparing the third braking mode, which will be described later. 
     Because an operation of the integrated master cylinder  1200  in the second braking mode is the same as the operation of the integrated master cylinder  1200  in the first to third braking modes of electronic brake system described above, a description thereof will be omitted to prevent duplication of contents. 
     The electronic brake system  3000  according to the third embodiment of the present disclosure may switch from the second braking mode to the third braking mode illustrated in  FIG. 13  when a braking pressure higher than that in the second braking mode is to be provided. 
       FIG. 13  is a hydraulic circuit diagram illustrating that the electronic brake system  3000  according to the third embodiment of the present disclosure performs the third braking mode. 
     Referring to  FIG. 13 , when a displacement or an operating speed of the brake pedal  10  detected by the pedal displacement sensor  11  is higher than a preset level or a hydraulic pressure detected by the pressure sensor is higher than a preset level, the electronic control unit may switch from the second braking mode to the third braking mode by determining that a higher braking pressure is required. 
     When the second braking mode is switched to the third braking mode, the motor (not shown) operates to rotate in one direction, and the rotational force of the motor is transferred to the hydraulic pressure providing unit by the power conversion unit so that the hydraulic piston  1320  of the hydraulic pressure providing unit moves forward again, thereby generating a hydraulic pressure in the first pressure chamber  1330 . The hydraulic pressure discharged from the first pressure chamber  1330  is transferred to the respective wheel cylinders  20  through the hydraulic control unit  3400 , the first hydraulic circuit  1510 , and the second hydraulic circuit  1520 , thereby generating a braking force. 
     Specifically, the hydraulic pressure generated in the first pressure chamber  1330  is thirdly transferred to the first wheel cylinder  21  and the second wheel cylinder  22  provided in the first hydraulic circuit  1510  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fourth hydraulic flow path  1404 . At this time, as the first valve  1411  and the third valve  1413  are provided as check valves allowing only the flow of the pressurized medium directing to the first hydraulic circuit  1510  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the first and second wheel cylinders  21  and  22 . The first inlet valve  1511   a  and the second inlet valve  1511   b  provided in the first hydraulic circuit  1510  are maintained in the open state, and the first outlet valve  1512   a,  the second outlet valve  1512   b,  and the discharge valve  1550  are maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the reservoir  1100  side. 
     Also, the hydraulic pressure of the pressurized medium generated in the first pressure chamber  1330  is thirdly transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24  provided in the second hydraulic circuit  1520  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403 , and the fifth hydraulic flow path  1405 . As described above, as the first valve  1411  and the fourth valve  1414  are provided as check valves allowing only the flow of the pressurized medium directing to the second hydraulic circuit  1520  side from the first pressure chamber  1330 , the hydraulic pressure of the pressurized medium may be smoothly transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24 . Also, the third inlet valve  1521   a  and the fourth inlet valve  1521   b  provided in the second hydraulic circuit  1520  are maintained in the open state, and the second cut valve  1622  is maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the second backup flow path  1620  side. 
     Because the hydraulic pressure of a high pressure is provided in the third braking mode, as the hydraulic piston  1320  moves forward, a force of the hydraulic pressure in the first pressure chamber  1330  to move the hydraulic piston  1320  backward also increases, so that a load applied to the motor increases rapidly. Accordingly, in the third braking mode, the fifth valve  3415  is operated to open, thereby allowing the flow of the pressurized medium through the sixth hydraulic flow path  3406 . In other words, a part of the hydraulic pressure generated in the first pressure chamber  1330  may be supplied to the second pressure chamber  1340  by sequentially passing through the first hydraulic flow path  1401 , the sixth hydraulic flow path  3406 , and the second flow path  1402 , and through this, the first pressure chamber  1330  and the second pressure chamber  1340  are in communication with each other to synchronize the hydraulic pressure, so that the load applied to the motor may be reduced and the durability and reliability of the devices may be improved. 
     Because an operation of the integrated master cylinder  1200  in the third braking mode is the same as the operation of the integrated master cylinder  1200  in the first to third braking modes of electronic brake system described above, a description thereof will be omitted to prevent duplication of contents. 
     Also, because an operation method of releasing the braking in the normal operation mode of the electronic brake system  3000  according to the third embodiment of the present disclosure is the same as the operation method of releasing the braking in the normal operation mode of the electronic brake system  1000  according to the first embodiment of the present disclosure described above, a separate description thereof will be omitted. 
     Hereinafter, an electronic brake system  4000  according to a fourth embodiment of the present disclosure will be described. 
       FIG. 14  is a hydraulic circuit diagram illustrating the electronic brake system  4000  according to the fourth embodiment of the present disclosure, and referring to  FIG. 14 , an integrated master cylinder  4200  according to the fourth embodiment may further include a first simulator spring  4271  provided to elastically support the first simulation piston  1230 , and a second simulator spring  4272  provided to elastically support the second simulation piston  4272 . 
     Because the following description of the electronic brake system  4000  according to the fourth embodiment of the present disclosure except for additional explanation with separate reference numerals is the same as the above description of the electronic brake system  3000  according to the third embodiment of the present disclosure, a description thereof will be omitted in order to prevent redundant description. 
     The first simulator spring  4271  is provided to elastically support the first simulation piston  1230 . To this end, one end of the first simulation spring  4271  may be supported on the rear surface (left surface of  FIG. 14 ) of the first simulation piston  1230 , and the other end thereof may be supported on the front surface (right surface of  FIG. 14 ) of the second simulation piston  1240 . When the first simulation piston  1230  moves forward according to a braking operation to generate a displacement, the first simulator spring  4271  is compressed, and at this time, a pedal feeling may be provided to the driver together with the elastic member  1250  by the elastic restoring force. Thereafter, when the braking is released, as the first simulator spring  4271  expands by an elastic force thereof, the first simulation piston  1230  may return to the original position. 
     The second simulator spring  4272  is provided to elastically support the second simulation piston  1240 . As one end of the second simulator spring  4272  is supported on the cylinder block  1210  and the other end thereof is supported on the second simulation piston  1240 , the second simulator spring  4272  may elastically support the second simulation piston  1240 . When the second simulation piston  1240  moves forward according to the braking operation to generate a displacement, the second simulator spring  4272  is compressed, and thereafter, when the braking is released, as the second simulator spring  4272  expands by an elastic force thereof, the second simulation piston  1240  may return to the original position.