Patent Publication Number: US-2022219664-A1

Title: Electronic brake system and method for operating same

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 providing unit 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 providing unit 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 the 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 high-pressure braking 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 simulation chamber, a simulation piston provided in the simulation chamber to be displaceable by a brake pedal, a master chamber, a master piston provided in the master chamber to be displaceable by a displacement of the simulation piton or a hydraulic pressure of the simulation chamber, an elastic member provided between the simulation piston and the master piston, a piston spring elastically supporting the master piston, a simulation flow path connecting the simulation chamber to the reservoir, and a simulator valve provided in the simulation flow path to control a flow of a pressurized medium; a hydraulic pressure providing unit provided to generate a hydraulic pressure by operating a hydraulic piston according to an electrical signal output in response to a displacement of the brake pedal; a hydraulic pressure control unit including a first hydraulic circuit provided to control the hydraulic pressure to be transferred to two wheel cylinders, and a second hydraulic circuit provided to control the hydraulic pressure to be transferred to other two wheel cylinders; an electronic control unit configured to control valves based on hydraulic pressure information and displacement information of the brake pedal; a backup flow path connecting the simulation chamber to the first hydraulic circuit; an auxiliary backup flow path connecting the master chamber to the backup flow path; and an inspection valve provided in the auxiliary backup flow path to control a flow of the pressurized medium. 
     The hydraulic pressure providing device may include: a first pressure chamber provided on one side of the hydraulic piston movably accommodated in a cylinder block to be connected to one or more of the wheel cylinders; and a second pressure chamber provided on an other side of the hydraulic piston to be connected to one or more of the wheel cylinders, and wherein the hydraulic pressure control unit may include: a first hydraulic flow path in communication with the first pressure chamber; a second hydraulic flow path branched from the first hydraulic flow path to be connected to the first hydraulic circuit; a third hydraulic flow path branched from the first hydraulic flow path to be connected to the second hydraulic circuit; a fourth hydraulic flow path in communication with the second pressure chamber; a fifth hydraulic flow path connecting the first hydraulic flow path to fourth hydraulic flow path; and a sixth hydraulic flow path branched from the first hydraulic flow path to be connected to the fifth hydraulic flow path. 
     The hydraulic pressure control unit may include a first vale provided in the first hydraulic flow path to control a flow of the pressurized medium and a second vale provided in the sixth hydraulic flow path to control a flow of the pressurized medium. 
     The first valve may be provided as a check valve for allowing only a flow of the pressurized medium discharged from the first pressure chamber, and the second valve may be provided as a solenoid valve for controlling bidirectional flows of the pressurized medium. 
     The electronic brake system may further include a cut valve provided in the back up flow path to control a flow of the pressurized medium. 
     The electronic brake system may further include a reservoir flow path configured to communicate the integrated master cylinder with the reservoir, and wherein the reservoir flow path may include a first reservoir flow path connecting the reservoir to the simulation chamber and a second reservoir flow path branched from an upstream side of the simulation flow path and rejoining at a downstream side of the simulation flow path. 
     The electronic brake system may further include a reservoir valve provided in the second reservoir flow path, and allowing only a flow of the pressurized medium from the reservoir toward the simulation chamber. 
     The first hydraulic circuit may include: a first inlet valve and a second inlet valve provided to control the flow of the pressurized medium to be supplied to a first wheel cylinder and a second wheel cylinder, respectively; and 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 a third wheel cylinder and a fourth wheel cylinder, respectively, and a first outlet valve and a second outlet valve provided to control the flow of the pressurized medium to be discharged from the third wheel cylinder and the fourth wheel cylinder to the reservoir, respectively, and the backup flow path may be provided to connect at least one of downstream sides of the first and second inlet valves to the simulation chamber. 
     The electronic brake system may further include a dump controller provided between the reservoir and the hydraulic pressure providing device to control a flow of the pressurized medium, wherein the dump controller may include: a dump flow path provided to connect the first pressure chamber to the reservoir; a dump check valve provided in the dump flow path to allow only a flow of the pressurized medium from the reservoir toward the first pressure chamber; a bypass flow path connected in parallel to the dump check valve on the dump flow path; and a dump valve provided in the bypass flow path to control bidirectional flows of the pressurized medium. 
     The hydraulic pressure control unit further includes a third valve provided in the fourth hydraulic flow path to control a flow of the pressurized medium. 
     The third valve may be provided as a solenoid valve for controlling bidirectional flows of the pressurized medium. 
     Another aspect of the present disclosure provides an operation method of the electronic brake system according to claim  4 , including a first braking mode in which, as the hydraulic pressure of the pressurized medium transferred from the hydraulic pressure providing unit to the wheel cylinder gradually increases, the hydraulic pressure is primarily provided according to a forward movement of the hydraulic piston; and a second braking mode in which the hydraulic pressures is secondarily provided according to a backward movement of the hydraulic piston after the first braking mode. 
     In the first braking mode, the second valve may be opened, and the hydraulic pressure generated in the first pressure chamber according to a forward movement of the hydraulic piston may be provided to the first hydraulic circuit by sequentially passing through the first hydraulic flow path and the second hydraulic flow path, and provided to the second hydraulic circuit by sequentially passing through the first hydraulic flow path and the third hydraulic flow path, and at least a 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, the fifth hydraulic flow path, and the fourth hydraulic flow path. 
     In the second braking mode, the second valve may be closed, and the hydraulic pressure generated in the second pressure chamber according to a backward movement of the hydraulic piston after the first braking mode may be provided to the first hydraulic circuit by sequentially passing through the fourth hydraulic flow path, the fifth hydraulic flow path, and the second hydraulic flow path, and provided to the second hydraulic circuit by sequentially passing through the fourth hydraulic flow path, the fifth hydraulic flow path, and the third hydraulic flow path. 
     In a releasing of the first braking mode, the second valve may be opened, and a negative pressure may be generated in the first pressure chamber according to a backward movement of the hydraulic piston such that the pressurized medium provided to the first hydraulic circuit may be recovered to the first pressure chamber by sequentially passing through the second hydraulic flow path, the fifth hydraulic flow path, the sixth hydraulic flow path, and the first hydraulic flow path, and the pressurized medium provided to the second hydraulic circuit may be recovered to the first pressure chamber by sequentially passing through the third hydraulic flow path, the fifth hydraulic flow path, the sixth hydraulic flow path, and the first hydraulic flow path, and the pressurized medium in the second pressure chamber may be supplied to the first pressure chamber by sequentially passing through the fourth hydraulic flow path, the fifth hydraulic flow path, the sixth hydraulic flow path, and the first hydraulic flow path. 
     In a releasing of the second braking mode, the second valve may be closed, and a negative pressure may be generated in the second pressure chamber according to a forward movement of the hydraulic piston such that the pressurized medium provided to the first hydraulic circuit may be recovered to the second pressure chamber by sequentially passing through the second hydraulic flow path, the fifth hydraulic flow path, and the fourth hydraulic flow path, and the pressurized medium provided to the second hydraulic circuit may be recovered to the second pressure chamber by sequentially passing through the third hydraulic flow path, the fifth hydraulic flow path, and the fourth hydraulic flow path. 
     Another aspect of the present disclosure provides an operation method of the electronic brake system according to claim  5 , wherein in a normal operation mode, the inspection valve is closed to seal the master chamber, and the cut valve is closed but the simulator valve is opened to communicate the simulation chamber with the reservoir such that as the brake pedal operates for the simulation piston to compress the elastic member, and an elastic restoring force of the elastic member is provided to a driver as a pedal feeling. 
     In an abnormal operation mode, the inspection valve may be opened for the master chamber to communicate with the first hydraulic circuit, and the simulator valve may be closed but the cut valve may be opened for the simulation chamber to communicate with the first hydraulic circuit, and the pressurized medium in the simulation chamber may be provided to the first hydraulic circuit through the backup flow path according to a stepping force of the brake pedal, the pressurized medium in the mater chamber may be provided to the first hydraulic circuit by sequentially passing through the auxiliary backup flow path and the backup flow path, and at least a part of the pressurized medium provided to the first hydraulic circuit may be provided to the second hydraulic circuit. 
     In an inspection mode of inspecting a leak of the integrated master cylinder or the simulator valve, the simulator valve and the inspection valve may be closed, the hydraulic pressure generated according to an operation of the hydraulic pressure providing unit may be provided to the simulation chamber by sequentially passing through the hydraulic pressure control unit and the backup flow path, and an expected hydraulic pressure value expected to occur based on a displacement amount of the hydraulic piston may be compared with a hydraulic pressure value measured by a pressure sensor in the first hydraulic circuit or the simulation chamber to identify a leak. 
     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 high-pressure braking 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 component 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 releases the second 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 the first 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. 
     
    
    
     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 an integrated master cylinder  1200 , a reservoir  1100  in which a pressurized medium is stored, a hydraulic pressure providing unit  1300  provided to receive an electrical signal corresponding to a braking intention 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 pressure control unit  1400  provided to control the hydraulic pressure provided from the hydraulic pressure providing unit  1300 , first and second hydraulic circuits  1510  and  1520  having wheel cylinders  21 ,  22 ,  23 , and  24  for braking respective heels RR, RL, FR, and FL as the hydraulic pressure of the pressurized medium is transferred, a dump controller  1800  provided between the hydraulic pressure providing unit  1300  and the reservoir  1100  to control a flow of the pressurized medium, a backup flow path  1610  provided to hydraulically connect the integrated master cylinder  1200  and the first and second 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 providing unit  1300  and various valves based on hydraulic pressure information and pedal displacement information. 
     The integrated master cylinder  1200  includes a master chamber  1230   a  and a simulation 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 and second hydraulic circuits  1510  and  1520  side, which will be described below. The integrated master cylinder  1200  may be configured such that the pedal simulation part and the master cylinder 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 simulation chamber  1220   a  formed on an inlet side of the cylinder block  1210  to which the brake pedal  10  is connected, a simulation piston  1220  provided in the simulation chamber  1220   a  and connected to the brake pedal  10  to be displaceable depending on the operation of the brake pedal  10 , the master chamber  1230   a  formed more inside than the simulation chamber  1220   a  on the cylinder block  1210 , a master piston  1230  provided in the master chamber  1230   a  to be displaceable by a displacement of the simulation piston  1220  or a hydraulic pressure of the pressurized medium accommodated in the simulation chamber  1220   a , an elastic member  1240  disposed between the simulation piston  1220  and the master piston  1230  to provide a pedal feeling through an elastic restoring force generated during compression, a piston spring  1270  provided to elastically support the master piston  1230 , a first simulator spring (not shown) provided to elastically support the simulation piston  1220  on the cylinder block  1210 , a second simulator spring (not shown) provided to elastically support the simulation piston  1220  while being interposed between the simulation piston  1220  and the master piston  1230 , a simulation flow path  1260  provided to connect the simulation chamber  1220   a  to the reservoir  1100 , and a simulator valve  1261  provided in the simulation flow path  1260  to control the flow of the pressurized medium. 
     The simulation chamber  1220   a  and the master chamber  1230   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 simulation piston  1220  and the master piston  1230  are disposed in the simulation chamber  1220   a  and the master chamber  1230   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 simulation 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 simulation piston  1220  connected to the brake pedal  10  via an input rod  12  may be accommodated in the simulation chamber  1220   a  to enable reciprocating movement. 
     The pressurized medium may be introduced into and discharged from the simulation chamber  1220   a  through a first hydraulic port  1280   a , a second hydraulic port  1280   b , and a third hydraulic port  1280   c . The first hydraulic port  1280   a  is connected to a first reservoir flow path  1710 , which will be described below, so that the pressurized medium may be introduced into the simulation chamber  1220   a  from the reservoir  1100 , and the third hydraulic port  1280   c  is connected to the simulation flow path  1260 , which will be described below, so that the pressurized medium accommodated in the simulation chamber  1220   a  may be discharged to the reservoir  1100  side, or conversely, the pressurized medium may be introduced from the reservoir  1100 . In addition, the second hydraulic port  1280   b  is connected to a backup flow path  1610 , which will be described below, so that the pressurized medium may be discharged from the simulation chamber  1220   a  into the backup flow path  1610 , or conversely, the pressurized medium may be introduced into the simulation chamber  1220   a  from the 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 from the reservoir  1100  toward the simulation chamber  1220   a  through the first reservoir flow path  1710 , while blocking the flow of the pressurized medium from the simulation chamber  1220   a  toward the first reservoir flow path  1710 . 
     The simulation piston  1220  may be accommodated in the simulation chamber  1220   a , and configured to generate a hydraulic pressure of the pressurized medium accommodated in the simulation chamber  1220   a , or pressurize the elastic member  1240 , which will be described below, by moving forward, and configured to generate a negative pressure inside the simulation chamber  1220   a  or return the elastic member  1240  to its original position and shape by moving backward. 
     The master chamber  1230   a  may be formed at an inner side (left side of  FIG. 1 ) of the simulation chamber  1220   a  on the cylinder block  1210 , and the master piston  1230  may be accommodated in the master chamber  1230   a  to enable reciprocating movement. 
     The pressurized medium may be introduced into and discharged from the master chamber  1230   a  through a fourth hydraulic port  1280   d . The fourth hydraulic port  1280   d  is connected to an auxiliary backup flow path  1620 , which will be described below, so that the pressurized medium accommodated in the master chamber  1230   a  may be discharged into the backup flow path  1610  side, or conversely, the pressurized medium may be introduced from the backup flow path  1610  toward the master chamber  1230   a.    
     The master piston  1230  may be accommodated in the master chamber  1230   a , and configured to generate a hydraulic pressure of the pressurized medium accommodated in the master chamber  1230   a  by moving forward, or generate a negative pressure inside the master chamber  1230   a  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 master piston  1230  to prevent leakage of the pressurized medium between the adjacent chambers. 
     The integrated master cylinder  1200  according to the present embodiment may secure safety in the event of a failure of a component by including the simulation chamber  1220   a  and the master chamber  1230   a . For example, the simulation chamber  1220   a  may be connected to any wheel cylinders  21 ,  22 ,  23 , and  24  of a right front wheel FR, a left front wheel FL, a left rear wheel RL, and a right rear wheel RR through the backup flow path  1610 , which will be described below, 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 described below with reference to  FIG. 6 . 
     The elastic member  1240  is interposed between the simulation piston  1220  and the master piston  1230  and provided to provide a pedal feeling of the brake pedal  10  to the driver by its own elastic restoring force. The elastic member  1240  may be made of a material such as compressible and expandable rubber, and when a displacement occurs in the simulation piston  1220  by the operation of the brake pedal  10 , but when the master piston  1230  is maintained in an original position thereof, the elastic member  1240  is compressed, and the driver may receive a stable and familiar pedal feel by the elastic restoring force of the compressed elastic member  1240 . A detailed description thereof will be described below. 
     Accommodating grooves recessed in a shape corresponding to the shape of the elastic member  1240  to facilitate smooth compression and deformation of the elastic member  1240  may be provided on a rear surface (left surface of  FIG. 1 ) of the simulation piston  1220  and a front surface (right surface of  FIG. 1 ) of the master piston  1230 , which face the elastic member  1240 , respectively. 
     The piston spring  1270  is provided to elastically support the master piston  1230 . One end of the piston spring  1270  may be supported on the cylinder block  1210 , and the other end may be supported on the master piston  1230 , to elastically support the master piston  1230 . When the master piston  1230  moves forward according to a braking operation and a displacement occurs, the piston spring  1270  is compressed, and when the braking is released, as the piston spring  1270  expands by an elastic force thereof, the master piston  1230  may return to the original position. 
     The simulation flow path  1260  is provided to connect a rear side of the simulation chamber  1220   a  (left side of  FIG. 1 ) to the reservoir  1100 . A 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 . The simulator valve  1261  may be closed in a normal operation of the electronic brake system  1000  to seal the simulation chamber  1220   a , and may be closed in an inspection mode of inspecting whether the integrated master cylinder  1200  or the simulator valve  1261  has a leak. A detailed description thereof will be provided below. 
     The auxiliary backup flow path  1620  is provided to connect the master chamber  1230   a  to the backup flow path  1610  to communicate the simulation chamber  1220   a  with the master chamber  1230   a . The auxiliary backup flow path  1620  may be provided with an inspection valve  1621  for controlling bidirectional flows of the pressurized medium. The inspection valve  1621  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 inspection valve  1621  may be closed in a normal operation mode of the electronic brake system  1000 . 
     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 providing unit  1300 , which will be described below, and the hydraulic circuits, which will be described below, 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 a front side (right side of  FIG. 1 ) of the simulation chamber  1220   a  to the reservoir  1100  and the second reservoir flow path  1720  branched from an upstream side of the simulation flow path  1260  connecting a rear side (left of  FIG. 1 ) of the simulation chamber  1220   a  to the reservoir  1100  and then rejoining at a downstream side of the simulation flow path  1260 . To this end, one ends of the first reservoir flow path  1710  and the simulation flow path  1260  may communicate with the simulation chamber  1220   a  of the integrated master cylinder  1200  and the other ends may communicate with the reservoir  1100 . 
     A reservoir valve  1721  for controlling a flow of a pressurized medium may be provided in the second reservoir flow path  1720 . The reservoir valve  1721  may be provided as a check valve for allowing the flow of the pressurized medium from the reservoir  1100  toward the simulation chamber  1220   a , while blocking the flow of the pressurized medium from the simulation chamber  1220   a  toward the reservoir  1100 . 
     Explaining a pedal simulation operation by the integrated master cylinder  1200 , in a normal operation, at the same time as the driver operates the brake pedal  10 , a cut valve  1611  provided in each of the backup flow paths  1610 , which will be described below, is closed, while the inspection valve  1621  of the auxiliary backup flow path  1620  is closed and the simulator valve  1261  of the simulation flow path  1260  is opened. As the operation of the brake pedal  10  progresses, the simulation piston  1220  moves forward, but since the simulation chamber  1220   a  is sealed by a closing operation of the cut valve  1611 , the hydraulic pressure of the pressurized medium accommodated in the simulation chamber  1220   a  is transferred to the simulation piston  1220 , so that the simulation piston  1220  moves forward to generate a displacement. On the other hand, as the inspection valve  1621  is closed, the master chamber  1230   a  is sealed so that a displacement of the master piston  1230  is not generated, and thus the elastic member  1240  is compressed by the displacement of the simulation piston  1220 , and the elastic restoring force by compression of the elastic member  1240  may be provided to the driver as a pedal feeling. In this case, the pressurized medium accommodated in the simulation chamber  1220   a  is transferred to the reservoir  1100  through the simulation flow path  1260 . After that, when the driver releases the pressing force of the brake pedal  10 , the elastic member  1240  returns to the original shape and position thereof by the elastic restoring force, and the simulation chamber  1220   a  may be filled with the pressurized medium supplied from the reservoir  1100  through the simulation flow path  1260 . 
     As such, because the inside of the simulation chamber  1220   a  and the master chamber  1230   a  is always filled with the pressurized medium, when the pedal simulation is operated, friction of the simulation piston  1220  and the master piston  1230  is minimized, so that the durability of the integrated master cylinder  1200  is improved, and 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 below with reference to  FIG. 6 . 
     The hydraulic pressure providing unit  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 providing unit  1300  may include a hydraulic pressure providing unit to provide a pressure to the pressurized medium to be transferred to the wheel cylinders  21 ,  22 ,  23 , and  24 , 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 below, and the second pressure chamber  1340  is connected to a fourth hydraulic flow path  1404 , which will be described below. 
     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 fourth hydraulic flow path  1404 , which will be described below. 
     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 providing unit  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 described below. 
     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 providing unit  1300  may be hydraulically connected to the reservoir  1100  by the dump controller  1800 . The dump controller  1800  may include a dump flow path  1810  connecting the first pressure chamber  1330  and the reservoir  1100 , and a bypass flow path  1820  that is branched from the dump flow path  1810  and rejoins the dump flow path  1810 . 
     A dump check valve  1811  and a dump valve  1821  for controlling the flow of the pressurized medium may be provided in the dump flow path  1810  and the bypass flow path  1820 , respectively. The dump check valve  1811  may be provided to allow only the flow of the pressurized medium from the reservoir  1100  toward the first pressure chamber  1330  and block the flow of the pressurized medium in the opposite direction. The bypass flow path  1820  is connected in parallel with respect to the dump check valve  1811  in the dump flow path  1810 , and the dump valve  1821  for controlling the flow of the pressurized medium between the first pressure chamber  1330  and the reservoir  1100  may be provided in the bypass flow path  1820 . In other words, the bypass flow path  1820  may bypass the dump check valve  1811  on the dump flow path  1810  to connect a front side and a rear side of the dump check valve  1811 , and the dump valve  1821  may be provided as a bidirectional solenoid valve for controlling the flow of the pressurized medium between the first pressure chamber  1330  and the reservoir  1100 . The dump valve  1821  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 hydraulic pressure control unit  1400  may be provided to control a hydraulic pressure transferred to the respective wheel cylinders  21 ,  22 ,  23 , and  24 , and the electronic control unit (ECU) is provided to control the hydraulic pressure providing unit  1300  and various valves based on the hydraulic pressure information and pedal displacement information. 
     The hydraulic pressure control unit  1400  may include a 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  21 ,  22 ,  23 , and  24 , and a 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 providing unit  1300  to the wheel cylinders  21 ,  22 ,  23 , and  24 . 
     The first hydraulic flow path  1401  is provided to be in communication with the first pressure chamber  1330  and may be branched into a second hydraulic flow path  1402  and a third hydraulic flow path  1403 . Also, the fourth hydraulic flow path  1404  is provided to be in communication with the second pressure chamber  1340 , a fifth hydraulic flow path  1405  is provided to connect the first hydraulic flow path  1401  to the fourth hydraulic flow path  1404 , and a sixth hydraulic flow path  1406  is provided to be branched from the first hydraulic flow path  1401  to be connected to the fifth hydraulic flow path  1405 . 
     The second hydraulic flow path  1402  and the third hydraulic flow path  1403  branched from the first hydraulic flow path  1401  are provided to be connected to the first hydraulic circuit and the second hydraulic circuit, respectively. 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 for allowing the flow of the pressurized medium from the first pressure chamber toward the first and second hydraulic circuits  1510  and  1520 , while blocking the flow of the pressurized medium in the opposite direction. Also, a second valve  1412  for controlling the flow of the pressurized medium may be provided in the sixth hydraulic flow path  1406 , and the second valve  1412  may be provided as a bidirectional control valve for controlling the flow of the pressurized medium. 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. 
     By the arrangement of the hydraulic flow paths and valves of the hydraulic pressure 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  and the second hydraulic flow path  1402 , and may be transferred to the second hydraulic circuit  1520  by sequentially passing through the first hydraulic flow path  1401  and the third hydraulic flow path  1403 . 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 fourth hydraulic flow path  1404 , the fifth hydraulic flow path  1405 , and the second hydraulic flow path  1402 , and may be transferred to the second hydraulic circuit  1520  by sequentially passing through the fourth hydraulic flow path  1404 , the fifth hydraulic flow path  1405 , and the third hydraulic flow path  1403 . 
     Conversely, the negative pressure generated in the first pressure chamber  1330  according to the backward movement of the hydraulic piston  1320  may recover the pressurized medium provided in the first hydraulic circuit  1510  to the first pressure chamber  1330  by sequentially passing through the second hydraulic flow path  1402 , the sixth hydraulic flow path  1406 , and the first hydraulic flow path  1401 , and may recover the pressurized medium provided in the second hydraulic circuit  1520  to the first pressure chamber  1330  by sequentially passing through the third hydraulic flow path  1403 , the sixth hydraulic flow path  1406 , and the first hydraulic flow path  1401 . Also, the negative pressure generated in the second pressure chamber  1340  according to the forward movement of the hydraulic piston  1320  may recover the pressurized medium provided in the first hydraulic circuit  1510  to the second pressure chamber  1340  by sequentially passing through the second hydraulic flow path  1402 , the fifth hydraulic flow path  1405 , and the fourth hydraulic flow path  1404 , and may recover the pressurized medium provided in the second hydraulic circuit  1520  to the second pressure chamber  1340  by sequentially passing through the third hydraulic flow path  1403 , the fifth hydraulic flow path  1405 , and the fourth hydraulic flow path  1404 . 
     In addition, the negative pressure generated in the first pressure chamber  1330  according to the backward movement of the hydraulic piston  1320  may supply the pressurized medium from the reservoir  1100  to the first pressure chamber  1330  through the dump flow path  1810 . 
     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 described below with reference to  FIGS. 2 to 5 . 
     The first hydraulic circuit  1510  of the hydraulic pressure control unit  1400  may control the hydraulic pressure in the first wheel cylinder  21  and the second wheel cylinder  22 , which are two wheel cylinders  21 ,  22 ,  23 , and  24  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  21 ,  22 ,  23 , and  24 . 
     The first hydraulic circuit  1510  may receive the hydraulic pressure through the second hydraulic flow path  1402  from the hydraulic pressure providing unit  1300 , and the second hydraulic flow path  1402  may be provided to be branched into two flow paths, which are connected to the first wheel cylinder  21  and the second wheel cylinder  22 . Similarly, the second hydraulic circuit  1520  may receive the hydraulic pressure through the third hydraulic flow path  1403  from the hydraulic pressure providing unit  1300 , and the third hydraulic flow path  1403  may be provided to be branched into two flow paths, which are connected to the third wheel cylinder  23  and the fourth wheel cylinder  24 . 
     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  21 ,  22 ,  23 , and  24 , 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 the bypass flow paths that connect 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  21 ,  22 ,  23 , and  24  to the hydraulic pressure providing unit  1300 , while blocking the flow of the pressurized medium from the hydraulic pressure providing unit  1300  to the wheel cylinders  21 ,  22 ,  23 , and  24 . 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  21 ,  22 ,  23 , and  24  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  21 ,  22 ,  23 , and  24  may be smoothly returned to the hydraulic pressure providing unit. 
     The first and second wheel cylinders  21  and  22  of the first hydraulic circuit  1510  may be connected to flow paths branched from the backup flow path  1610 , which will be described below, and the backup flow path  1610  may be provided with at least one cut valve  1611  for controlling the flow of the pressurized medium between the first and second wheel cylinders  21  and  22  (further, the third and fourth wheel cylinders  23  and  24 ) and the integrated master cylinder  1200 . 
     The second hydraulic circuit  1520  may include first and second outlet valves  1522   a  and  1522   b  for controlling the flow of the pressurized medium discharged from the third and fourth wheel cylinders  23  and  24  to improve performance when braking of the third and fourth wheel cylinders  23  and  24  is released. The first and second outlet valves  1522   a  and  1522   b  are provided on discharge sides of the third and fourth wheel cylinders  23  and  24 , respectively, to control the flow of the pressurized medium transferred from the third and fourth wheel cylinders  23  and  24  to the reservoir  1100 . The first and second outlet valves  1522   a  and  1522   b  may be provided as normally closed type solenoid valves that operate to be opened when an electric signal is received from the electronic control unit in a normally closed state. In an ABS braking mode of the vehicle, the first and second outlet valves  1522   a  and  1522   b  may selectively release the hydraulic pressure of the pressurized medium applied to the first and second wheel cylinders  21  and  22  and transfer the released hydraulic pressure of the pressurized medium to the reservoir  1100  side. 
     The electronic brake system  1000  according to the present embodiment may include the backup flow paths  1610  to implement braking by directly supplying the pressurized medium discharged from the integrated master cylinder  1200  to the wheel cylinders  21 ,  22 ,  23 , and  24  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  21 ,  22 ,  23 , and  24  is referred to as an abnormal operation mode, that is, a fallback mode. 
     The backup flow path  1610  may be provided to connect the simulation chamber  1220   a  of the integrated master cylinder  1200  to the first hydraulic circuit  1510 , and further to the second hydraulic circuit  1520 . Specifically, the backup flow path  1610  may have one end connected to the simulation chamber  1220   a  and the other end connected between the first inlet valve  1511   a  and the cut valve  1611  on the first hydraulic circuit  1510 . Although  FIG. 1  illustrates that the backup flow path  1610  is connected between the first inlet valve  1511   a  and the cut valve  1611 , the same structure may be provided when the first backup flow path  1610  is branched and connected to at least one of upstream sides of the cut valve  1611 . 
     The cut valve  1611  is a valve for controlling bidirectional flows of the pressurized medium, and 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. 
     As illustrated in  FIG. 1 , a pair of the cut valves  1611  may be provided on the first wheel cylinder  21  and the second wheel cylinder  22 , respectively, and may selectively release the hydraulic pressure of the pressurized medium applied to the first wheel cylinder  21  and the second wheel cylinder  22  in the ABS braking mode of the vehicle so that the released hydraulic pressure of the pressurized medium may be discharged to the reservoir  1100  side by sequentially passing through the backup flow path  1610 , the simulation chamber  1220   a , and the simulation flow path  1260 . Accordingly, when the cut valves  1611  are closed, the pressurized medium in the integrated master cylinder  1200  may be prevented from being directly transferred to the wheel cylinders  21 ,  22 ,  23 , and  24 , and at the same time the hydraulic pressure provided from the hydraulic pressure providing unit  1300  may be supplied to the first and second hydraulic circuits  1510  and  1520  side through the hydraulic pressure control unit  1400 , and when the cut valves  1611  and the inspection valve  1621  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 backup flow paths  1610 , thereby performing braking. 
     The electronic brake system  1000  according to the present embodiment may include a pressure sensor PS 2  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 2  is provided in the first hydraulic circuit  1510  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 by 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 divided into a first braking mode and a second braking mode as the hydraulic pressure transferred from the hydraulic pressure providing unit  1300  to the wheel cylinders  21 ,  22 ,  23 , and  24  increases. Specifically, in the first braking mode, the hydraulic pressure by the hydraulic pressure providing unit  1300  may be primarily provided to the wheel cylinders  21 ,  22 ,  23 , and  24 , and in the second braking mode, the hydraulic pressure by the hydraulic pressure providing unit  1300  may be secondarily provided to the wheel cylinders  21 ,  22 ,  23 , and  24  to transfer a higher braking pressure than in the first braking mode. 
     The first and second braking modes may be changed by changing the operations of the hydraulic pressure providing unit  1300  and the hydraulic pressure control unit  1400 . The hydraulic pressure providing unit  1300  may provide a sufficiently high hydraulic pressure of the pressurized medium without a high specification motor  120  by utilizing the first and second 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 the present disclosure performs the first braking mode. 
     Referring to  FIG. 2 , 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  21 ,  22 ,  23 , and  24  through the hydraulic pressure control unit  1400 , the first hydraulic circuit  1510  and the second hydraulic circuit  1520 , thereby generating a braking force. 
     Specifically, a part of 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  and the second hydraulic flow path  1402 . In this case, as the first valve  1411  is provided as a check valve for allowing only the flow of the pressurized medium from the first pressure chamber  1330  toward the first and second hydraulic circuits  1510  and  1520 , 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 cut valve  1611  is maintained in a closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the backup flow path  1610  side. 
     The hydraulic pressure 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 . As described above, as the second valve  1412  is provided as a check valve for allowing only the flow of the pressurized medium discharged from the first pressure chamber  1330  toward the first and second hydraulic circuits  1510  and  1520 , 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 the first and second outlet valves  1522   a  and  1522   b  are maintained in a closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the reservoir  1100  side. 
     In the first braking mode, a part of the hydraulic pressure of the pressurizing medium generated in the first pressure chamber  1330  may be supplied to the second pressure chamber  1340 . As the hydraulic piston  1320  moves forward to generate a hydraulic pressure in the first braking mode, a part of the pressurization medium accommodated in the first pressure chamber  1330  is supplied to and filled in the second pressure chamber  1340 , so that the second braking mode, which will be described below, may be prepared. To this end, in the first braking mode, the second valve  1412  is operated to open, so that the flow of the pressurized medium through the sixth hydraulic flow path  1406  and the fifth hydraulic flow path  1405  may be allowed. 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  1406 , the fifth hydraulic flow path  1405 , and the fourth hydraulic flow path  1404 . 
     The dump valve  1821  provided in the bypass flow path  1820  is maintained in a closed state, thereby preventing the hydraulic pressure of the pressurized medium generated in the first pressure chamber  1330  from leaking into the reservoir  1100  side. 
     In the first braking mode in which braking of the wheel cylinders  21 ,  22 ,  23 , and  24  is performed by the hydraulic pressure providing unit  1300 , the cut valve  1611  provided in the backup flow path  1610  is 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  21 ,  22 ,  23 , and  24  side. 
     Specifically, as a pressing force is applied to the brake pedal  10 , the pressurized medium accommodated in the simulation chamber  1220   a  is pressurized to generate a hydraulic pressure, the hydraulic pressure of the pressurized medium generated in the simulation chamber  1220   a  is transferred to the front surface (right side of  FIG. 2 ) of the simulation piston  1220 , and because the simulator valve  1261  is opened in the normal operation mode, a displacement occurs in the simulation piston  1220 . On the other hand, because the inspection valve  1621  is closed in the normal operation mode of the electronic brake system  1000 , the master chamber  1230   a  is sealed so that no displacement occurs in master piston  1230 , and thus the elastic member  1240  is compressed by the displacement of the simulation piston  1220 , and the elastic restoring force by the compression of the elastic member  1240  is provided to the driver as a pedal feeling. In this case, the pressurized medium accommodated in the simulation chamber  1220   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 shown 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  21 ,  22 ,  23 , and  24  through the hydraulic pressure 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 fourth hydraulic flow path  1404 , the fifth hydraulic flow path  1405 , and the second hydraulic flow path  1402 . 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 cut valve  1611  is maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the backup flow path  1610  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 fourth hydraulic flow path  1404 , the fifth hydraulic flow path  1405 , and the third hydraulic flow path  1403 . 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 first and second outlet valves  1522   a  and  1522   b  are maintained in the closed state, thereby preventing the hydraulic pressure of the pressurized medium from leaking into the reservoir  1100  side. 
     In the second braking mode, as the second valve  1412  provided in the sixth hydraulic flow path  1406  is switched to a closed state, the hydraulic pressure of the pressurized medium generated in the second pressure chamber  1340  may be prevented from leaking into the first pressure chamber  1330 , and the first pressure chamber  1330  may be filled with the pressurized medium supplied from the reservoir  1100  through the dump flow path  1810 . In this case, the dump valve  1821  provided in the bypass flow path  1820  is switched to an open state as necessary, so that the flow of the pressurized medium from the reservoir  1100  toward the first pressure chamber  1330  may be allowed. 
     Hereinafter, an operation method of the electronic brake system  1000  according to the present embodiment in which the braking is released from the normal operation mode will be described. 
       FIG. 4  is a hydraulic circuit diagram illustrating that the hydraulic piston  1320  of the electronic brake system  1000  according to the present embodiment moves forward to release the second braking mode. 
     Referring to  FIG. 4 , when the pressing force applied to the brake pedal  10  is released, the motor generates a rotational force in one direction and transfers the rotational force to the power conversion unit, and the power conversion unit moves the hydraulic piston  1320  forward. Accordingly, the hydraulic pressure in the first pressure chamber  140  is released, and at the same time, a negative pressure may be generated, so that the pressurized medium in the wheel cylinders  21 ,  22 ,  23 , and  24  may be transferred to the second pressure chamber  1340 . 
     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  is recovered to the second pressure chamber  1340  by sequentially passing through the second hydraulic flow path  1402 , the first hydraulic flow path  1401 , the fifth hydraulic flow path  1405 , and the fourth hydraulic flow path  1404 . In this case, the second valve  1412  is closed to prevent the recovered pressurized medium from leaking into the first pressure chamber  1330 . 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 cut valve  1611  is maintained in the closed state. 
     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  by the negative pressure generated in the second pressure chamber  1340  is recovered to the second pressure chamber  1340  by sequentially passing through the third hydraulic flow path  1403 , the first hydraulic flow path  1401 , the fifth hydraulic flow path  1405 , and the fourth hydraulic flow path  1404 . The third inlet valve  1521   a  and the fourth inlet valve  1521   b  provided in the second hydraulic circuit  1520  are provided in the open state, and the first and second outlet valves  1522   a  and  1522   b  are maintained in a closed state. When the second braking mode is released, the dump valve  1821  may be opened to smoothly implement the forward movement of the hydraulic piston  1320 . 
     After the releasing of the second braking mode is completed, it may be switched to the releasing operation of the first braking mode illustrated in  FIG. 5  in order to completely release the braking pressure applied to the wheel cylinders  21 ,  22 ,  23 , and  24 . 
       FIG. 5  is a hydraulic circuit diagram illustrating that the hydraulic piston  1320  of the electronic brake system  1000  according to the present embodiment moves backward to release the first braking mode. 
     Referring to  FIG. 5 , when the pressing force applied to the brake pedal  10  is released, the motor generates a rotational force in the other direction and transfers the rotational force to the power conversion unit, and the power conversion unit moves the hydraulic piston  1320  backward. Accordingly, a negative pressure may be generated in the first pressure chamber  1330 , so that the pressurized medium in the wheel cylinders  21 ,  22 ,  23 , and  24  may be transferred to the first pressure chamber  1330 . 
     Specifically, the hydraulic pressure in the first and second wheel cylinders  21  and  22  provided in the first hydraulic circuit  1510  is recovered to the first pressure chamber  1330  by sequentially passing through the second hydraulic flow path  1402 , the fifth hydraulic flow path  1405 , the sixth hydraulic flow path  1406 , and the first hydraulic flow path  1401 . In this case, the second valve  1416  is opened to allow the flow of the pressurized medium through the sixth hydraulic flow path  1406 , and the dump valve  1821  is closed to effectively generate a negative pressure in the first pressure chamber  1330 . In addition, in order to enable the hydraulic piston  1320  to quickly and smoothly move backward, the pressurized medium accommodated in the second pressure chamber  1340  is transferred to the first pressure chamber  1330  by sequentially passing through the fourth hydraulic flow path  1404 , the fifth hydraulic flow path  1405 , the sixth hydraulic flow path  1406 , and the first hydraulic flow path  1401 . 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 cut valve  1611  is maintained in the closed state. 
     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  by the negative pressure generated in the first pressure chamber  1330  is recovered to the first pressure chamber  1330  by sequentially passing through the third hydraulic flow path  1403 , the fifth hydraulic flow path  1405 , the sixth hydraulic flow path  1406 , and the first hydraulic flow path  1401 . 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 first and second outlet valves  1522   a  and  1522   b  are maintained in the closed state. 
     Hereinafter, an operation method in a case where the electronic brake system  1000  according to the present embodiment does not operate normally, that is, in the fallback mode will be described. 
       FIG. 6  is a hydraulic circuit diagram illustrating the operation of the electronic brake system  1000  according to the present embodiment in the abnormal operation mode (fallback mode) when a normal operation is impossible due to a device failure or the like. 
     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. In this case, when the driver depresses the brake pedal  10 , the simulation piston  1220  connected to the brake pedal  10  moves forward to generate a displacement. Because the cut valve  1611  is opened in the non-operational state, the forward movement of the simulation piston  1220  may cause the pressurized medium accommodated in the simulation chamber  1220   a  to be transferred to the first wheel cylinder  21  and the second wheel cylinder  22  of the first hydraulic circuit  1510  along the backup flow path  1610 , thereby performing braking. In this case, because the simulator valve  1261  of the simulation flow path  1260  is provided in a closed state in the non-operational state, the pressurized medium accommodated in the simulation chamber  1220   a  may be transferred to the backup flow path  1610  without being discharged to the reservoir  1100 , and at the same time, may generate a hydraulic pressure for moving the master piston  1230  forward. In addition, since the inspection valve is opened so that the master chamber  1230   a  and the first hydraulic circuit  1510  may communicate with each other, the displacement of the simulation piston  1220  causes the master piston  1230  also to move forward so that a displacement occurs in the master piston  1230 . Accordingly, the pressurized medium accommodated in the master chamber  1230   a  may be provided to the first hydraulic circuit  1510  by sequentially passing through the auxiliary backup flow path  1620  and the backup flow path  1610 . Furthermore, the pressurized medium transferred to the first hydraulic circuit  1510  may be transferred to the third wheel cylinder  23  and the fourth wheel cylinder  24  of the second hydraulic circuit  1520  along the second hydraulic flow path  1402  and the third hydraulic flow path  1403 , thereby performing braking. 
     Hereinafter, the inspection mode of an electronic brake system  1000  according to the first embodiment of the present disclosure will be described.  FIG. 7  is a hydraulic circuit diagram illustrating the inspection mode of the electronic brake system  1  according to the first embodiment of the present disclosure performs, and referring to  FIG. 7 , the electronic brake system  1000  according to the present embodiment may perform the inspection mode of inspecting whether the integrated master cylinder  1200  or the simulator valve  1261  has a leak. When the inspection mode is performed, the electronic control unit controls to supply the hydraulic pressure generated from the hydraulic pressure providing unit  1300  to the simulation chamber  1220  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 a 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 simulator valve  1261  is switched to a closed state, and the cut valve  1611  is maintained in the open state. Accordingly, the hydraulic pressure generated in the first pressure chamber  1330  is transferred to the first hydraulic circuit  1510  side by sequentially passing through the first hydraulic flow path  1401  and the second hydraulic flow path  1402 , and because the first inlet valve  1511   a  and the second inlet valve  1511   b  are maintained in a normally open state, the pressurized medium transferred to the first hydraulic circuit  1510  is introduced into the simulation chamber  1220   a  through the backup flow path  1610 . In this case, the inspection valve  1621  is maintained in the closed state to induce the simulation chamber  1220   a  to be in a sealed state. 
     In order to quickly perform the inspection mode, the third inlet valve  1521   a  and the fourth inlet valve  1521   b  provided in the second hydraulic circuit  1520  may be switched to the closed state. 
     In this state, an expected hydraulic pressure value of the pressurized medium to be generated by the displacement of the hydraulic piston  1320  is compared with a hydraulic pressure value in the simulation chamber  1220   a  measured by the pressure sensor PS 1  or in the first hydraulic circuit  1510  measured by the pressure sensor PS 2 , so that 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 rotation angle measured by a motor control sensor (not shown) is compared with an actual hydraulic pressure value measured by the pressure sensor PS 1  or PS 2 , 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 1  or PS 2  is lower than the expected hydraulic pressure value calculated based on the displacement amount of the hydraulic piston  1320  or the rotation angle measured by the motor control sensor (not shown), because this is due to the loss of a part of the hydraulic pressure of the pressurized medium applied to the simulation chamber  1220   a , it is 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. Because except for additional explanations with separate reference numerals, the following description of the electronic brake system  2000  according to the second embodiment of the present disclosure is the same as the above description of the electronic brake system  1000  according to the first embodiment of the present disclosure, in order to prevent redundant description, a description thereof will be omitted. 
     Referring to  FIG. 8 , a hydraulic pressure control unit  2400  according to the second embodiment of the present disclosure may further include a third valve  2413  provided in the fourth hydraulic flow path  1404  to control the flow of the pressurized medium. The third valve  2413  may be provided as a bidirectional control valve for controlling the flow of the pressurized medium. The third valve  2413  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. For example, the third valve  2413  is provided in the fourth hydraulic flow path  1404  communicating with the second pressure chamber  1340 , so that when a leak occurs in the second pressure chamber  1340 , the third valve  2413  is provided to be switched to be closed, thereby preventing a leak described above. 
     Hereinafter, operation methods of the electronic brake system  2000  according to the second embodiment of the present disclosure will be described. 
     In the first braking mode during the normal operation mode of the electronic brake system  2000  according to the present embodiment, a part of the hydraulic pressure formed in the first pressure chamber  1330  is transferred to the second pressure chamber  1340  by sequentially passing through the first hydraulic flow path  1401 , the sixth hydraulic flow path  1406 , the fifth hydraulic flow path  1405 , and the fourth hydraulic flow path  1404 , and to this end, the second valve  1412  provided in the sixth hydraulic flow path  1406  and the third valve  2413  provided in the fifth hydraulic flow path  1405  are opened. 
     In the second braking mode, the third valve  1416  is maintained in the open state to allow the flow of the pressurized medium through the fifth hydraulic flow path  1405 , and the second valve  1412  provided in the sixth hydraulic flow path  1406  is switched to be closed to prevent the hydraulic pressure of the pressurized medium formed in the second pressure chamber  1340  from leaking into the first pressure chamber  1330 . 
     In a releasing of the second braking mode, the third valve  2413  is opened to allow the flow of the pressurized medium through the fifth hydraulic flow path  1405 , and the second valve  1412  provided in the sixth hydraulic flow path  1406  is closed to prevent the recovered pressurized medium from leaking into the first pressure chamber  1330 . 
     In a releasing of the first braking mode, the pressurized medium accommodated in the second pressure chamber  1340  is transferred to the first pressure chamber  1330  by sequentially passing through the fourth hydraulic flow path  1404 , the fifth hydraulic flow path  1405 , the sixth hydraulic flow path  1406 , and the firth hydraulic flow path  1401  so as to promote the rapid and smooth backward movement of the hydraulic piston  1320 . To this end, the second valve  1412  provided in the sixth hydraulic flow path  1406  is switched to be open, and the third valve  2413  provided in the fifth hydraulic flow path  1405  is maintained in an open state. 
     Among the operation methods of the electronic brake system  2000  according to the second embodiment of the present disclosure, the abnormal operation mode and the inspection mode are the same as the operation methods of the electronic brake system  1000  according to the first embodiment described above, so the description will be omitted.