Patent Publication Number: US-2022227344-A1

Title: Electric brake system and operation method

Description:
TECHNICAL FIELD 
     The disclosure relates to an electronic brake system and an operation method thereof, and more specifically, 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 
     A brake system for braking of a vehicle is essentially mounted to a vehicle, and a variety of brake systems have been recently proposed for the safety of drivers and passengers. 
     In a conventional brake system, when a driver operates a brake pedal, hydraulic pressure for braking is supplied to wheel cylinders using a booster mechanically connected to the brake pedal. Due to the high market demand for various brake functions, however, an electronic brake system provided with a hydraulic pressure supply device and an operation method thereof have recently come into widespread use. Once a driver operates a brake pedal, the hydraulic pressure supply device of the electronic brake system detects a displacement of the brake pedal through a pedal displacement sensor, and receives an electrical signal indicating the driver&#39;s braking intention from the pedal displacement sensor, such that the hydraulic pressure required for braking is supplied to wheel cylinders. 
     In the electronic brake system and operation method thereof described above, in a normal operation mode, an electrical signal is generated and provided when a driver depresses the brake pedal, and the hydraulic pressure supply device electrically operates and is controlled based on the electrical signal to generate and transfer hydraulic pressure required for braking to the wheel cylinders. As described above, since the electronic brake system and operation method thereof are electrically operated and controlled, complicated and various braking operations may be performed. However, when a technical malfunction occurs in an electric component, a hydraulic pressure required for braking is not stably generated, which may threaten the safety of passengers. Accordingly, when a component fails or becomes out of control, the electronic brake system enters an abnormal operation mode, and in this case, a mechanism in which a driver&#39;s brake pedal operation is directly linked to the wheel cylinders is required. That is, in the abnormal operation mode of the electronic brake system and operation method thereof, when the driver depresses the brake pedal, a hydraulic pressure required for braking is required to be immediately generated and transferred directly to the wheel cylinders. 
     DISCLOSURE 
     Technical Problem 
     An embodiment of the disclosure provides an electronic brake system and an operation method thereof that may reduce the number of components and implement product miniaturization and weight reduction by integrating a master cylinder and a simulation apparatus into one. 
     An embodiment of the disclosure provides an electronic brake system and an operation method thereof that may implement stable and effective braking even in various operating situations. 
     An embodiment of the disclosure provides an electronic brake system and an operation method thereof that may stably generate a high braking pressure. 
     An embodiment of the disclosure provides an electronic brake system and an operation method thereof that may improve a performance and operational reliability. 
     An embodiment of the disclosure provides an electronic brake system and an operation method thereof that may improve ease of assembly and productivity of a product, as well as reducing manufacturing costs. 
     Technical Solution 
     According to an aspect of the disclosure, there is provided an electronic brake system, including: a reservoir in which a pressurized medium is stored; an integrated master cylinder including a first simulation chamber, a second simulation chamber, a first master chamber and a second master chamber having a smaller diameter than the second simulation chamber, a first simulation piston provided to pressurize the first simulation chamber and be displaceable by a brake pedal, a second simulation piston provided to pressurize the second simulation chamber and the first master chamber and be displaceable by a displacement of the first simulation piston or a hydraulic pressure of the first simulation chamber, a master piston provided to pressurize the second master chamber and be displaceable by a displacement of the second simulation piston or a hydraulic pressure of the first master chamber, an elastic member provided between the first simulation piston and the second simulation piston, a first simulation flow path to connect the first simulation chamber and the reservoir, and a first simulator valve provided in the first simulation flow path to control a flow of the pressurized medium; a reservoir flow path to connect the integrated master cylinder and the reservoir; a hydraulic pressure supply device configured 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, and including a first pressure chamber provided on one side of the hydraulic piston accommodated to be movable in a cylinder block and connected to one or more wheel cylinders, and a second pressure chamber provided on another side of the hydraulic piston and connected to the one or more wheel cylinders; a hydraulic control unit having a first hydraulic circuit configured to control a hydraulic pressure transferred to two wheel cylinders and a second hydraulic circuit configured to control a hydraulic pressure transferred to other two wheel cylinders; and an electronic control unit configured to control valves based on hydraulic pressure information and displacement information of the brake pedal, wherein the hydraulic control unit includes 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 and connected to the first hydraulic circuit, a fifth hydraulic flow path branched from the third hydraulic flow path and connected to the second hydraulic circuit, a sixth hydraulic flow path in communication with the first hydraulic circuit, a seventh hydraulic flow path in communication with the second hydraulic circuit, an eighth hydraulic flow path in which the sixth hydraulic flow path and the seventh hydraulic flow path join, a ninth hydraulic flow path branched from the eight hydraulic flow path and connected to the first pressure chamber, and a tenth hydraulic flow path branched from the eight hydraulic flow path and connected to the second pressure chamber. 
     There is provided an electronic brake system, including: a reservoir in which a pressurized medium is stored; an integrated master cylinder having a master chamber and a simulation chamber to provide a driver with a reaction force corresponding to a pressing force of a brake pedal, and at the same time to pressurize and discharge a pressurized medium accommodated therein; a reservoir flow path to connect the integrated master cylinder and the reservoir; a hydraulic pressure supply device configured 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, and including a first pressure chamber provided on one side of the hydraulic piston accommodated to be movable in a cylinder block and connected to one or more wheel cylinders, and a second pressure chamber provided on another side of the hydraulic piston and connected to the one or more wheel cylinders; a hydraulic control unit having a first hydraulic circuit configured to control a hydraulic pressure transferred to two wheel cylinders and a second hydraulic circuit configured to control a hydraulic pressure transferred to other two wheel cylinders; and an electronic control unit configured to control valves based on hydraulic pressure information and displacement information of the brake pedal, wherein the hydraulic control unit includes 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 and connected to the first hydraulic circuit, a fifth hydraulic flow path branched from the third hydraulic flow path and connected to the second hydraulic circuit, a sixth hydraulic flow path in communication with the first hydraulic circuit, a seventh hydraulic flow path in communication with the second hydraulic circuit, an eighth hydraulic flow path in which the sixth hydraulic flow path and the seventh hydraulic flow path join, a ninth hydraulic flow path branched from the eight hydraulic flow path and connected to the first pressure chamber, and a tenth hydraulic flow path branched from the eight hydraulic flow path and connected to the second pressure chamber. 
     The hydraulic control unit includes 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, a fourth valve provided in the fifth hydraulic flow path to control the flow of the pressurized medium, a fifth valve provided in the sixth hydraulic flow path to control the flow of the pressurized medium, a sixth valve provided in the seventh hydraulic flow path to control the flow of the pressurized medium, a seventh valve provided in the ninth hydraulic flow path to control the flow of the pressurized medium, and an eighth valve provided in the tenth hydraulic flow path to control the flow of the pressurized medium. 
     The first valve is provided as a check valve that allows only the flow of the pressurized medium discharged from the first pressure chamber, the second valve is provided as a check valve that allows only the flow of the pressurized medium discharged from the second pressure chamber, the third valve is provided as a check valve that allows only the flow of the pressurized medium from the third hydraulic flow path to the first hydraulic circuit, the fourth valve is provided as a check valve that allows only the flow of the pressurized medium from the third hydraulic flow path to the second hydraulic circuit, the fifth valve is provided as a check valve that allows only the flow of the pressurized medium discharged from the first hydraulic circuit, the sixth valve is provided as a check valve that allows only the flow of the pressurized medium discharged from the second hydraulic circuit, and the seventh valve and the eighth valve are provided as solenoid valves that control the flow of the pressurized medium in both directions. 
     The electronic brake system further includes a dump control unit provided between the reservoir and the hydraulic pressure supply device to control the flow of the pressurized medium, wherein the dump control unit includes a first dump flow path to connect the first pressure chamber and the reservoir, a first dump check valve provided in the first dump flow path and allowing only the flow of the pressurized medium from the reservoir to the first pressure chamber, a first bypass flow path connected in parallel to the first dump check valve on the first dump flow path, a first dump valve provided in the first bypass flow path to control the flow of the pressurized medium in both directions, a second dump flow path to connect the second pressure chamber and the reservoir, a second dump check valve provided in the second dump flow path and allowing only the flow of the pressurized medium from the reservoir to the second pressure chamber, a second bypass flow path connected in parallel to the second dump check valve on the second dump flow path, and a second dump valve provided in the second bypass flow path to control the flow of the pressurized medium in both directions. 
     The simulation chamber includes a first simulation chamber and a second simulation chamber, the master chamber includes a first master chamber and a second master chamber having a smaller diameter than the second simulation chamber, and the integrated master cylinder includes a first simulation piston provided to pressurize the first simulation chamber and be displaceable by the brake pedal, a second simulation piston provided to pressurize the second simulation chamber and the first master chamber and be displaceable by a displacement of the first simulation piston and a hydraulic pressure of the first simulation chamber, a master piston provided to pressurize the second master chamber and be displaceable by a displacement of the second simulation piston and a hydraulic pressure of the first master chamber, an elastic member provided between the first simulation piston and the second simulation piston, a simulation flow path to connect the first simulation chamber and the reservoir, and a simulator valve provided in the simulation flow path to control the flow of the pressurized medium. 
     The electronic brake system further includes a first backup flow path to connect the first simulation chamber and the first hydraulic circuit; a second backup flow path to connect the second master chamber and the second hydraulic circuit; an auxiliary backup flow path to connect the first master chamber and the first backup flow path; at least one first cut valve provided in the first backup flow path to control the flow of the pressurized medium; and at least one second cut valve provided in the second backup flow path to control the flow of the pressurized medium. 
     The reservoir flow path includes a first reservoir flow path including a reservoir valve to communicate the reservoir and the second simulation chamber and control the flow of the pressurized medium, a second reservoir flow path to communicate the reservoir and the first master chamber, and a third reservoir flow path to communicate the reservoir and the second master chamber. 
     The first hydraulic circuit includes a first inlet valve and a second inlet valve to control the flow of the pressurized medium supplied to a first wheel cylinder and a second wheel cylinder, respectively, and the second hydraulic circuit includes a third inlet valve and a fourth inlet valve to control the flow of the pressurized medium supplied to a third wheel cylinder and a fourth wheel cylinder, respectively. 
     The first valve is provided as a check valve that allows only the flow of the pressurized medium discharged from the first pressure chamber, the second valve is provided as a check valve that allows only the flow of the pressurized medium discharged from the second pressure chamber, the third valve is provided as a check valve that allows only the flow of the pressurized medium from the third hydraulic flow path to the first hydraulic circuit, the fifth valve is provided as a check valve that allows only the flow of the pressurized medium discharged from the first hydraulic circuit, the sixth valve is provided as a check valve that allows only the flow of the pressurized medium discharged from the second hydraulic circuit, and the fourth valve, the seventh valve and the eighth valve are provided as solenoid valves that control the flow of the pressurized medium in both directions. 
     The first hydraulic circuit includes a first wheel cylinder and a second wheel cylinder, and the second hydraulic circuit includes a third wheel cylinder and a fourth wheel cylinder, and the electronic brake system further includes: a generator provided in the third wheel cylinder and the fourth wheel cylinder, respectively. 
     The integrated master cylinder further includes a second simulation flow path to connect the first simulation chamber and the second simulation chamber, and the second simulation flow path includes a second simulator valve to control the flow of the pressurized medium. 
     There is provided an operation method of an electronic brake system, including: as the hydraulic pressure transferred from the hydraulic pressure supply device to the wheel cylinders gradually increases, a first braking mode in which the hydraulic pressure is primarily provided, a second braking mode in which the hydraulic pressure is secondly provided by a forward movement of the hydraulic piston, and a third braking mode in which the hydraulic pressure is thirdly provided by a forward movement of the hydraulic piston after the second braking mode. 
     In the first braking mode, the eighth valve and the first dump valve are closed, and a hydraulic pressure generated in the first pressure chamber by the forward movement of the hydraulic piston is 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 is 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 seventh valve and the second dump valve are closed, and a hydraulic pressure generated in the second pressure chamber by a backward movement of the hydraulic piston after the first braking mode is 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 is 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 seventh valve and the eighth valve are open, the first dump valve and the second dump valve are closed, a portion of the hydraulic pressure generated in the first pressure chamber by the forward movement of the hydraulic piston is 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 is 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 a remaining portion of the hydraulic pressure generated in the first pressure chamber is provided to the second pressure chamber by sequentially passing through the ninth hydraulic flow path and the tenth hydraulic flow path. 
     When the first braking mode is released, the seventh valve and the second dump valve are open, the eighth valve and the first dump valve are closed, a negative pressure is generated in the first pressure chamber by a backward movement of the hydraulic piston, the pressurized medium provided to the first hydraulic circuit is recovered to the first pressure chamber by sequentially passing through the sixth hydraulic flow path, the eighth hydraulic flow path and the ninth hydraulic flow path, and the pressurized medium provided to the second hydraulic circuit is recovered to the first pressure chamber by sequentially passing through the seventh hydraulic flow path, the eighth hydraulic flow path and the ninth hydraulic flow path. 
     When the second braking mode is released, the eighth valve and the first dump valve are open, the seventh valve and the second dump valve are closed, a negative pressure is generated in the second pressure chamber by the forward movement of the hydraulic piston, the pressurized medium provided to the first hydraulic circuit is recovered to the second pressure chamber by sequentially passing through the sixth hydraulic flow path, the eighth hydraulic flow path and the tenth hydraulic flow path, and the pressurized medium provided to the second hydraulic circuit is recovered to the second pressure chamber by sequentially passing through the seventh hydraulic flow path, the eighth hydraulic flow path and the tenth hydraulic flow path. 
     When the third braking mode is released, the seventh valve and the eighth valve are open, the first dump valve is closed, a negative pressure is generated in the first pressure chamber by the backward movement of the hydraulic piston, the pressurized medium provided to the first hydraulic circuit is recovered to the first pressure chamber by sequentially passing through the sixth hydraulic flow path, the eighth hydraulic flow path and the ninth hydraulic flow path, the pressurized medium provided to the second hydraulic circuit is recovered to the first pressure chamber by sequentially passing through the seventh hydraulic flow path, the eighth hydraulic flow path and the ninth hydraulic flow path, and at least a portion of the pressurized medium in the second pressure chamber is supplied to the first pressure chamber by sequentially passing through the tenth hydraulic flow path and the ninth hydraulic flow path. 
     There is provided an operation method of an electronic brake system, wherein, in a regenerative braking mode by the generator, a hydraulic pressure generated in the first pressure chamber by a forward movement of the hydraulic piston is 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 is prevented to be provided to the third wheel cylinder and the fourth wheel cylinder by closing the fourth valve. 
     Advantageous Effects 
     According to the embodiment of the disclosure, an electronic brake system and an operation method thereof can reduce the number of components and implement product miniaturization and weight reduction. 
     According to the embodiment of the disclosure, the electronic brake system and the operation method thereof can implement stable and effective braking even in various operating situations. 
     According to the embodiment of the disclosure, the electronic brake system and the operation method thereof can stably generate a high braking pressure. 
     According to the embodiment of the disclosure, the electronic brake system and the operation method thereof can improve a performance and operational reliability. 
     According to the embodiment of the disclosure, the electronic brake system and the operation method thereof can stably provide a braking pressure even when a component fails or a pressurized medium leaks. 
     According to the embodiment of the disclosure, the electronic brake system and the operation method thereof can improve ease of assembly and productivity of a product, as well as reducing manufacturing costs. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a hydraulic circuit diagram illustrating an electronic brake system according to a first embodiment of the disclosure. 
         FIG. 2  is a hydraulic circuit diagram illustrating that the electronic brake system according to the first embodiment of the 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 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 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 disclosure operates to release the third braking mode. 
         FIG. 6  is a hydraulic circuit diagram illustrating that the electronic brake system according to the first embodiment of the disclosure operates to release the second braking mode. 
         FIG. 7  is a hydraulic circuit diagram illustrating that the electronic brake system according to the first embodiment of the disclosure operates to release the first braking mode. 
         FIG. 8  is a hydraulic circuit diagram illustrating that the electronic brake system according to the first embodiment of the disclosure operates (fallback mode) in an abnormal state. 
         FIG. 9  is a hydraulic circuit diagram illustrating that the electronic brake system according to the first embodiment of the disclosure operates in an ABS dump mode. 
         FIG. 10  is a hydraulic circuit diagram illustrating that the electronic brake system according to the first embodiment of the disclosure operates in a diagnosis mode. 
         FIG. 11  is a hydraulic circuit diagram illustrating an electronic brake system according to a second embodiment of the disclosure. 
         FIG. 12  is a hydraulic circuit diagram illustrating that the electronic brake system according to the second embodiment of the disclosure operates in a regenerative braking mode. 
         FIG. 13  is a hydraulic circuit diagram illustrating an electronic brake system according to a third embodiment of the disclosure. 
         FIG. 14  is a hydraulic circuit diagram illustrating that the electronic brake system according to the third embodiment of the disclosure operates (fallback mode) in an abnormal state. 
         FIG. 15  is a hydraulic circuit diagram illustrating that the electronic brake system according to the third embodiment of the disclosure operates in a diagnosis mode. 
     
    
    
     BEST MODE OF THE DISCLOSURE 
     Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The following embodiments are provided to fully convey the spirit of the disclosure to a person having ordinary skill in the art to which the present disclosure belongs. The disclosure is not limited to the embodiments shown herein but may be embodied in other forms. The drawings are not intended to limit the scope of the 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 disclosure. 
     Referring to  FIG. 1 , the electronic brake system  1000  includes a reservoir  1100 , an integrated master cylinder  1200 , a hydraulic pressure supply device  1300 , a hydraulic control unit  1400 , hydraulic circuits  1510  and  1520 , a dump control unit  1800 , backup flow paths  1610 ,  1620  and  1630 , a reservoir flow path  1700 , and an electronic control unit (ECU, not shown). A pressurized medium is stored in the reservoir  1100 . The integrated master cylinder  1200  provides a driver with a reaction force corresponding to a pressing force of a brake pedal  10  and pressurizes and discharges a pressurized medium accommodated therein such as a brake oil, etc. The hydraulic pressure supply device  1300  receives an electrical signal corresponding to a driver&#39;s braking intention from a pedal displacement sensor  11  detecting a displacement of the brake pedal  10  and generates a hydraulic pressure of the pressurized medium through a mechanical operation. The hydraulic control unit  1400  controls the hydraulic pressure provided from the hydraulic pressure supply device  1300 . The hydraulic circuits  1510  and  1520  include wheel cylinders  20  that perform braking of respective wheels RR, RL, FR and FL by receiving a hydraulic pressure of the pressurized medium. The dump control unit  1800  is provided between the hydraulic pressure supply device  1300  and the reservoir  1100  to control a flow of the pressurized medium. The backup flow paths  1610 ,  1620  and  1630  hydraulically connect the integrated master cylinder  1200  and the hydraulic circuits  1510  and  1520 . The reservoir flow path  1700  hydraulically connects the integrated master cylinder  1200  and the reservoir  1100 . The ECU controls 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 master chambers  1220   a  and  1220   b  to, when the driver presses the brake pedal  10  for braking, provide a reaction force against the pressing to the driver to provide a stable pedal feeling, 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 feeling to the driver, and a master cylinder part to transfer the pressurized medium to the second hydraulic circuit  1520  to be described later. 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 one cylinder block  1210 . 
     Specifically, the integrated master cylinder  1200  includes the cylinder block  1210 , the first simulation chamber  1240   a,  a first simulation piston  1240 , the second simulation chamber  1230   a,  a second simulation piston  1230 , the first master chamber  1220   a,  the second master chamber  1220   b,  a master piston  1220 , an elastic member  1250 , a simulator spring  1232 , a piston spring  1222 , a first simulation flow path  1260  and a first simulator valve  1261 . The cylinder block  1210  has a chamber formed therein, and the first simulation chamber  1240   a  is formed on an inlet side of the cylinder block  1210  to which the brake pedal  10  is connected. The first simulation piston  1240  is provided in the first simulation chamber  1240   a  and connected to the brake pedal  10  to be displaceable by an operation of the brake pedal  10 . The second simulation chamber  1230   a  is formed more inside than the first simulation chamber  1240   a  on the cylinder block  1210 . The second simulation piston  1230  is provided in the second simulation chamber  1230   a  to be displaceable by a displacement of the first simulation piston  1240  or a hydraulic pressure of the pressurized medium accommodated in the first simulation chamber  1240   a.  The first master chamber  1220   a  and the second master chamber  1220   b  are formed more inside than the second simulation chamber  1230   a  on the cylinder block  1210  and have a smaller diameter than the second simulation chamber  1230   a.  The master piston  1220  is provided in the second master chamber  1220   b  and provided to be displaceable by a displacement of the second simulation piston  1230  and a hydraulic pressure of the pressurized medium accommodated in the first master chamber  1220   a.  The elastic member  1250  is disposed between the first and second simulation pistons  1240  and  1230  to provide a pedal feeling through an elastic restoring force generated during compression. The simulator spring  1232  elastically supports the second simulation piston  1230  and the piston spring  1222  elastically supports the master piston  1220 . The first simulation flow path  1260  connects the first simulation chamber  1240   a  and the reservoir  1100 , and the first simulator valve  1261  is provided in the first simulation flow path  1260  to control the flow of the pressurized medium. 
     The first simulation chamber  1240   a,  the second simulation chamber  1230   a,  the first master chamber  1220   a,  and the second master chamber  1220   b  may be sequentially provided from the brake pedal  10  side (a right side based on  FIG. 1 ) from an inside (a left side based on  FIG. 1 ) on the cylinder block  1210  of the integrated master cylinder  1200 . 
     The first simulation piston  1240  is provided in the first simulation chamber  1240   a  and may generate a hydraulic pressure or negative pressure in the pressurized medium accommodated therein by moving forward or backward. 
     The second simulation piston  1230  spans the second simulation chamber  1230   a  and the first master chamber  1220   a  and may generate a hydraulic pressure or negative pressure in the pressurized medium accommodated in each of the chambers by moving forward or backward. Specifically, the second simulation piston  1230  has one end (an end to the second simulation chamber  1230   a  side) having a larger diameter than another end (an end to the first master chamber  1220   a ), and thus the one end seals the second simulation chamber  1230   a  side and the other end seals the first master chamber  1220   a  to partition each of the chambers. Accordingly, as the second simulation piston  1230  moves forward or backward, the second simulation piston  1230  may generate a hydraulic pressure or negative pressure in the pressurized medium accommodated in the second simulation chamber  1230   a  and the first master chamber  1220   a  simultaneously. 
     The master piston  1220  is provided in the second master chamber  1220   b  and may generate a hydraulic pressure or negative pressure in the pressurized medium accommodated therein by moving forward or backward. 
     The first simulation chamber  1240   a  may be formed on the inlet side or the outermost side (the right side based on  FIG. 1 ) of the cylinder block  1210 , and the first simulation piston  1240  connected to the brake pedal  10  through an input rod  12  may be accommodated in the first simulation chamber  1240   a  to enable reciprocating movement. 
     The pressurized medium may be introduced into or discharged from the first simulation chamber  1240   a  through a first hydraulic port  1280   a  and a second hydraulic port  1280   b.  The first hydraulic port  1280   a  is connected to the first simulation flow path  1260  to be described later, so that the pressurized medium may be introduced or discharged from the first simulation chamber  1240   a  to the reservoir  1100 . Also, the second hydraulic port  1280   b  is connected to the first backup flow path  1610  to be described later, so that the pressurized medium may be discharged to the first backup flow path  1610  from the first simulation chamber  1240   a,  or conversely, the pressurized medium may be introduced into the first simulation chamber  1240   a from the first backup flow path  1610 .    
     Meanwhile, the first simulation chamber  1240   a  may be assisted to be in communication with the reservoir  1100  through an auxiliary hydraulic port  1280   h.  By connecting an auxiliary reservoir flow path  1740  to the auxiliary hydraulic port  1280   h,  the flow of the pressurized medium between the first simulation chamber  1240   a  and the reservoir  1100  may be assisted. A sealing member  1290   a  to be described later is provided in front (the left side based on  FIG. 1 ) of the auxiliary hydraulic port  1280   h,  so that supply of the pressurized medium from the auxiliary reservoir flow path  1740  to the first simulation chamber  1240   a  may be allowed, while a flow of the pressurized medium in opposite direction may be blocked. A sealing member  1290   b  to be described later is provided in a rear (the right side based on  FIG. 1 ) of the auxiliary reservoir flow path  1740 , so that the pressurized medium may be prevented from leaking to an outside of the cylinder block  1210  from the first simulation chamber  1240   a.    
     The first simulation piston  1240  is accommodated in the first simulation chamber  1240   a  to pressurize the pressurized medium accommodated in the first simulation chamber  1240   a  or pressurize the elastic member  1250  by moving forward (a left direction based on  FIG. 1 ) for generating a hydraulic pressure. Also, the first simulation piston  1240  may generate a negative pressure inside the first simulation chamber  1240   a  or return the elastic member  1250  to its original position and shape by moving backward (a right direction based on  FIG. 1 ). 
     The second simulation chamber  1230   a  may be formed inside (the left side based on FIG.  1 ) of the first simulation chamber  1240   a  on the cylinder block  1210 , and the second simulation piston  1230  may be accommodated in the second simulation chamber  1230   a  to enable reciprocating movement. 
     The pressurized medium may be introduced into or discharged from the second simulation chamber  1230   a  through a third hydraulic port  1280   c.  The third hydraulic port  1280   c  is connected to a first reservoir flow path  1710  to be described later, so that the pressurized medium accommodated in the second simulation chamber  1230   a  may be discharged to the reservoir  1100 , or conversely, may be introduced from the reservoir  1100 . 
     The second simulation piston  1230  is accommodated in the second simulation chamber  1230   a  to generate a hydraulic pressure of the pressurized medium accommodated in the second simulation chamber  1230   a  by moving forward, or to generate a negative pressure inside the second simulation chamber  1230   a  by moving backward. At the same time, the second simulation piston  1230  may generate a hydraulic pressure or negative pressure in the first master chamber  1220   a  to be described later by moving forward or backward. At least one sealing member  1290   c  may be provided between an inner wall of the cylinder block  1210  and an outer circumferential surface of one end (an end to the first simulation chamber  1240   a  side) of the second simulation piston  1230  in order to prevent leakage of the pressurized medium between adjacent chambers. 
     A step part formed in a stepped manner inwardly may be provided at a portion where the second simulation chamber  1230   a  is formed on the cylinder block  1210 , and an extension part provided in an outer circumferential surface of the second simulation piston  1230  is extended outwardly to be caught by the step part. Specifically, on the cylinder block  1210 , the step part formed in a stepped manner inwardly between the second simulation chamber  1230   a  and the first master chamber  1220   a  may be provided, and thus the first and second master chambers  1220   a  and  1220   b  may have a smaller diameter than the first and second simulation chambers  1240   a  and  1230   a.  Also, the extension part is provided at an end of the second simulation piston  1230  on a side of the first simulation chamber  1240   a  to be caught by the step part. The at least one sealing member  1290   c  is provided at the extension part to seal between the second simulation chamber  1230   a  and the first simulation chamber  1240   a,  and at the same time to pressurize the second simulation chamber  1230   a  when the second simulation piston  1230  moves forward. A sealing member  1290   d  at an end of the second simulation piston  1230  on a side of the first master chamber  1220   a  may seal between the second simulation chamber  1230   a  and the first master chamber  1220   a,  and at the same time, pressurize the first master chamber  1220   a  when the second simulation piston  1230  moves forward. 
     The first master chamber  1220   a  may be formed inside (the left side based on  FIG. 1 ) the second simulation chamber  1230   a  on the cylinder block  1210 , and the second simulation piston  1230  may be accommodated in the first master chamber  1220   a  to enable reciprocating movement. 
     The pressurized medium may be introduced into or discharged from the first master chamber  1220   a  through a fourth hydraulic port  1280   d  and a fifth hydraulic port  1280   e.  Specifically, the fourth hydraulic port  1280   d  is connected to a second reservoir flow path  1720  to be described later, and thus the pressurized medium may be discharged to the reservoir  1100 , or conversely, introduced from the reservoir  1100 . The fifth hydraulic port  1280   e  is connected to an auxiliary backup flow path  1630  to be described later, the pressurized medium may be discharged to the auxiliary backup flow path  1630  from the first master chamber  1220   a,  or conversely, may be introduced from the auxiliary backup flow path  1630  to the first master chamber  1220   a.  Meanwhile, a pair of sealing members  1290   d  may be provided in front of and at a rear of the fourth hydraulic port  1280   d  to prevent leakage of the pressurized medium. 
     The second simulation piston  1230  is accommodated in the first master chamber  1220   a,  and may generate a hydraulic pressure of the pressurized medium accommodated in the first master chamber  1220   a  by moving forward, or generate a negative pressure in the first master chamber  1220   a  by moving backward. 
     Also, the second simulation piston  1230  may include a cut-off hole  1231  to connect the first master chamber  1220   a  and the fourth hydraulic port  1280   d.  Specifically, the cut-off hole  1231  is formed through an inside of the second simulation piston  1230 , and when the second simulation piston  1230  is in its original position, the cut-off hole  1231  connects the first master chamber  1220   a  and the fourth hydraulic port  1280   d.  When the second simulation piston  1230  deviates from its original position, the cut-off hole  1231  and the fourth hydraulic port  1280   d  are out of joint, and thus a connection between the first master chamber  1220   a  and the second reservoir flow path  1720  may be blocked. That is, the cut-off hole  1231  may be provided to selectively connect the first master chamber  1220   a  and the second reservoir flow path  1720 . Accordingly, the second simulation piston  1230  connects the first master chamber  1220   a  and the reservoir  1100  in a normal operation mode to be described later, and in an abnormal operation mode, the second simulation piston  1230  moves, and thereby may block a connection between the first master chamber  1220   a  and the reservoir  1100 . 
     The first master chamber  1220   a  may be formed inside (the left side based on  FIG. 1 ) the second simulation chamber  1230   a  on the cylinder block  1210 , and the second simulation piston  1230  may be accommodated in the first master chamber  1220   a  to enable reciprocating movement. 
     The pressurized medium may be introduced into or discharged from the second master chamber  1220   b  through a sixth hydraulic port  1280   f  and a seventh hydraulic port  1280   g.  Specifically, the sixth hydraulic port  1280   f  is connected to a third reservoir flow path  1730  to be described later, so that the pressurized medium may be discharged to the reservoir  1100 , or conversely, introduced from the reservoir  1100 . The seventh hydraulic port  1280   g  is connected to the second backup flow path  1620  to be described later, so that the pressurized medium may be discharged to the second backup flow path  1620  from the second master chamber  1220   b,  or conversely, be introduced from the second backup flow path  1620  to the second master chamber  1220   b.  Meanwhile, a pair of sealing members  1290   e  may be provided in front of and at a rear of the sixth hydraulic port  1280   f  to prevent leakage of the pressurized medium. The master piston  1220  is accommodated in the second master chamber  1220   b,  and may generate a hydraulic pressure of the pressurized medium accommodated in the second master chamber  1220   b  by moving forward, or generate a negative pressure in the second master chamber  1220   b  by moving backward. 
     Also, the master piston  1220  may include a cut-off hole  1221  to connect the second master chamber  1220   b  and the sixth hydraulic port  1280   f  in the normal operation mode. 
     Specifically, the cut-off hole  1221  is formed through an inside of the master piston  1220 , and when the master piston  1220  is in its original position, the cut-off hole  1221  connects the second master chamber  1220   b  and the sixth hydraulic port  1280   f.  When the master piston  1220  deviates from its original position, the cut-off hole  1221  and the sixth hydraulic port  1280   f  are out of joint, and thus a connection between the second master chamber  1220   b  and the third reservoir flow path  1730  may be blocked. That is, the cut-off hole  1221  may be provided to selectively connect the second master chamber  1220   b  and the third reservoir flow path  1730 . Accordingly, the master piston  1220  connects the second master chamber  1220   b  and the reservoir  1100  in the normal operation mode to be described later, and in the abnormal operation mode, the master piston  1220  moves, and thereby may block a connection between the second master chamber  1220   b  and the reservoir  1100 . 
     Meanwhile, the integrated master cylinder  1200  according to the first embodiment of the disclosure may secure safety in the event of a failure of a component by utilizing the master chambers  1220   a  and  1220   b  and the simulation chambers  1230   a  and  1240   a.  For instance, the first simulation chamber  1240   a  and the first master chamber  1220   a  may be connected to any two wheel cylinders  20  among 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  and the auxiliary backup flow path  1630 , which will be described later, and also the second master chamber  1220   b  may be connected to the other two wheel cylinders  20  through the second backup flow path  1620  to be described later. Accordingly, even when an error such as a leak occurs in any one of the chambers, braking may be performed, which will be described in detail with reference to  FIG. 8 . 
     The elastic member  1250  is disposed between the first simulation piston  1240  and the second simulation piston  1230  and provides the driver with a pedal feeling of the brake pedal  10  by its elastic restoring force. The elastic member  1250  may be made of a material such as compressible and expandable rubber, and the like. When displacement occurs in the first simulation piston  1240  by an operation of the brake pedal  10 , but the second simulation piston  1230  maintains its original position, the elastic member  1250  is compressed, and the driver may receive a stable and familiar pedal feeling by an elastic restoring force of the compressed elastic member  1250 , which will be described in detail later. 
     A receiving groove formed to be recessed in a manner that corresponds to a shape of the elastic member  1250  may be provided at a rear (the left side based on  FIG. 1 ) of the first simulation piston  1240  facing the elastic member  1250 , for smooth compression and deformation of the elastic member  1250 . 
     The simulator spring  1232  is provided to elastically support the second simulation piston  1230 . One end of the simulator spring  1232  is supported by the master piston  1220 , and another end of the simulator spring  1232  is supported by the second simulation piston  1230  to elastically support the second simulation piston  1230 . When displacement occurs in the second simulation piston  1230  by moving forward due to braking, the simulator spring  1232  is compressed, and then when the braking is released, the simulator spring  1232  is expanded by an elastic force and the second simulation piston  1230  returns to its original position. 
     The piston spring  1222  is provided to elastically support the master piston  1220 . One end of the piston spring  1222  is supported by the cylinder block  1210  and another end of the piston spring  1222  is supported by the master piston  1220  to elastically support the master piston  1220 . When displacement occurs in the master piston  1220  by moving forward due to braking, the piston spring  1222  is compressed, and then when the braking is released, the piston spring  1222  is expanded by an elastic force and the master piston  1220  returns to its original position. 
     The first simulation flow path  1260  is provided to communicate the first simulation chamber  1240   a  and the reservoir  1100  and may be provided with the first simulator valve  1261  to control the flow of the pressurized medium in both directions. The first simulator valve  1261  may be provided as a normally closed type solenoid valve that operates to be open when an electrical signal is received from the ECU in a normally closed state. The first simulator valve  1261  may be open in the normal operation mode of the electronic brake system  1000 . 
     With respect to a pedal simulation operation by the integrated master cylinder  1200 , in a normal operation, when the driver operates the brake pedal  10 , at the same time, first cut valves  1611  and second cut valves  1621  provided in the first backup flow path  1610  and the second backup flow path  1620  to be described later are closed, and a reservoir valve  1711  provided in the first reservoir flow path  1710  is also closed. By contrast, the first simulator valve  1261  provided in the first simulation flow path  1260  is open. As the operation of the brake pedal  10  proceeds, the first simulation piston  1240  moves forward, but the first master chamber  1220   a  is closed by the closing operation of the first cut valves  1611 , the second master chamber  1220   b  is closed by the closing operation of the second cut valves  1621 , and the second simulation chamber  1230   a  is also closed by the closing operation of the reservoir valve  1711 . Accordingly, a hydraulic pressure of the pressurized medium accommodated in the first simulation chamber  1240   a  is transferred to the reservoir  1100  through the first simulation flow path  1260 , and thus the first simulation piston  1240  moves forward and a displacement occurs. By contrast, because the second simulation chamber  1230   a,  the first master chamber  1220   a  and the second master chamber  1220   b  are closed, a displacement does not occur in the second simulation piston  1230 . Accordingly, the elastic member  1250  is compressed by the displacement of the first simulation piston  1240 , and an elastic restoring force by the compression of the elastic member  1250  may be provided the driver with a pedal feeling. Afterwards, when the driver releases the pressing force of the brake pedal  10 , the elastic member  1250  returns to its original position and shape by the elastic restoring force, and the first simulation chamber  1240   a  may be supplied with the pressurized medium from the reservoir  1100  through the first simulation flow path  1260 , or be filled with the pressurized medium supplied from the first hydraulic circuit  1510  through the first backup flow path  1610  to be described later. 
     As described above, because an inside of each of the second simulation chamber  1230   a,  the first master chamber  1220   a  and the second master chamber  1220   b  is always filled with the pressurized medium, when the pedal simulation is operated, a friction of the second simulation chamber  1230   a  and the master piston  1220  is minimized, thereby improving a durability of the integrated master cylinder  1200  and preventing an inflow of foreign substances from an outside. 
     Meanwhile, when the electronic brake system  1000  is abnormally operated, i.e., when a fallback mode is performed, an operation of the integrated master cylinder  1200  will be described later with reference to  FIG. 8 . 
     The pressurized medium may be accommodated and stored in the reservoir  1100 . The reservoir  1100  is connected to each constituent component such as the integrated master cylinder  1200 , the hydraulic pressure supply device  1300  to be described later, the hydraulic circuits  1510  and  1520 , and the like, in order to supply or be supplied with the pressurized medium. Although a plurality of reservoirs  1100  are illustrated with the same reference numeral in the drawings as an example for better understanding, the reservoir  1100  may be provided as a single component or a plurality of independent and separate components. 
     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  that connects the second simulation chamber  1230   a  and the reservoir  1100 , the second reservoir flow path  1720  that connects the first master chamber  1220   a  and the reservoir  1100 , and the third reservoir flow path  1730  that connects the second master chamber  1220   b  and the reservoir  1100 . 
     The reservoir valve  1711  may be provided in the first reservoir flow path  1710  as a two-way control valve that controls a flow of a braking fluid delivered through the first reservoir flow path  1710 . The reservoir valve  1711  may be provided as a normally open type solenoid valve that operates to be closed when an electrical signal is received from the ECU in a normally open state. The reservoir valve  1711  may be closed in the normal operation mode of the electronic brake system  1000 . 
     The hydraulic pressure supply device  1300  is provided to generate a hydraulic pressure of the pressurized medium through a mechanical operation by receiving an electrical signal corresponding to the driver&#39;s braking intention from the pedal displacement sensor  11  that detects a displacement of the brake pedal  10 . 
     The hydraulic pressure supply device  1300  may include a motor (not shown) that generates a rotational force by the electrical signal received from the pedal displacement sensor  11 , and a power transfer unit (not shown) that converts a rotational motion of the motor into a linear motion to provide the linear motion to a hydraulic pressure providing unit. 
     The hydraulic pressure supply device  1300  includes a cylinder block  1310  provided to accommodate the pressurized medium, a hydraulic piston  1320  accommodated in the cylinder block  1310 , a sealing member  1350   a  provided between the hydraulic piston  1320  and the cylinder block  1310  to seal pressure chambers  1330  and  1340 , and a drive shaft  1390  that transfers power output from the power transfer unit to the hydraulic piston  1320 . 
     The pressure chambers  1330  and  1340  may include the first pressure chamber  1330  located on a front side (a left side of the hydraulic piston  1320  based on  FIG. 1 ) of the hydraulic piston  1320 , and the second pressure chamber  1340  located on a rear side (a right side of the hydraulic piston  1320  based on  FIG. 1 ) of the hydraulic piston  1320 . 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 a 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  to be described later through a first communication hole  1360   a  formed on the cylinder block  1310 . The second pressure chamber  1340  is connected to a second hydraulic flow path  1402  to be described later through a second communication hole  1360   b  formed on the cylinder block  1310 . 
     A piston sealing member  1350   a  is 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 . A hydraulic pressure or negative pressure in the first pressure chamber  1330  and the second pressure chamber  1340  generated by a forward or backward movement of the hydraulic piston  1320  may be transferred to the first hydraulic flow path  1401  and the second hydraulic flow path  1402  to be described later, by being sealed with the piston sealing member  1350   a  without leakage. 
     The motor (not shown) is provided to generate a driving force of the hydraulic piston  1320  by an electrical signal output from the ECU. The motor may include a stator and a rotor, and through the above, 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 related thereto is omitted. 
     The power transfer unit (not shown) is provided to convert a rotational force of the motor into a linear motion. For example, the power transfer unit may be provided to include 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 having 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 , through which the hydraulic piston  1320  may slidably move 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 transmitted to the ECU, and the ECU 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 . 
     By contrast, when the pressing force applied to the brake pedal  10  is released, the ECU drives the motor to rotate the worm shaft in an 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 the hydraulic pressure and negative pressure in the second pressure chamber  1340  may be implemented by operating in an opposite way to the operations described above. That is, when the displacement of the brake pedal  10  is detected by the pedal displacement sensor  11 , the detected signal is transmitted to the ECU, and the ECU drives the motor to rotate the worm shaft in an 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 in the cylinder block  1310 , thereby generating a hydraulic pressure in the second pressure chamber  1340 . 
     By contrast, when the pressing force applied to the brake pedal  10  is released, the ECU drives the motor in one direction to rotate the worm shaft in one direction. Accordingly, the worm wheel also rotates in the opposite 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 described above, the hydraulic pressure supply device  1300  may generate a hydraulic pressure and a negative pressure in each of the first pressure chamber  1330  and the second pressure chamber  1340  depending on the rotation direction of the worm shaft by the operation of the motor. Also, whether braking is performed by transferring a hydraulic pressure or whether braking is released using a negative pressure may be determined by controlling the valves, which will be described in detail later. 
     Meanwhile, the power transfer unit according to the first 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 with various structures and manners. 
     The hydraulic pressure supply device  1300  may be hydraulically connected to the reservoir  1100  by the dump control unit  1800 . The dump control unit  1800  may include a first dump flow path  1810  to connect the first pressure chamber  1330  and the reservoir  1100 , a first bypass flow path  1830  that rejoins after branching on the first dump flow path  1810 , a second dump flow path  1820  to connect the second pressure chamber  1340  and the reservoir  1100 , a second bypass flow path  1840  that rejoins after branching on the second dump flow path  1820 , and an auxiliary dump flow path  1850  to subsidiarily connect the first pressure chamber  1330  and the reservoir  1100 . 
     A first dump check valve  1811  and a first dump valve  1831  may be provided in the first dump flow path  1810  and the first bypass flow path  1830 , respectively, to control the flow of the pressurized medium. The first dump check valve  1811  may be provided to allow only the flow of the pressurized medium from the reservoir  1100  to the first pressure chamber  1330  and block the flow of the pressurized medium in an opposite direction. The first bypass flow path  1830  may be connected in parallel to the first dump check valve  1811  on the first dump flow path  1810 , and the first dump valve  1831  may be provided in the first bypass flow path  1830  to control the flow of the pressurized medium between the first pressure chamber  1330  and the reservoir  1100 . That is, the first bypass flow path  1830  may be connected by bypassing a front end and a rear end of the first dump check valve  1811  on the first dump flow path  1810 , and the first dump valve  1831  may be provided as a two-way solenoid valve that controls the flow of the pressurized medium between the first pressure chamber  1330  and the reservoir  1100 . The first dump valve  1831  may be provided as a normally closed type solenoid valve that operates to be open when an electrical signal is received from the ECU in a normally closed state. 
     A second dump check valve  1821  and a second dump valve  1841  may be provided in the second dump flow path  1820  and the second bypass flow path  1840 , respectively, to control the flow of the pressurized medium. The second dump check valve  1821  may be provided to allow only the flow of the pressurized medium from the reservoir  1100  to the second pressure chamber  1340  and block the flow of the pressurized medium in an opposite direction. The second bypass flow path  1840  may be connected in parallel to the second dump check valve  1821  on the second dump flow path  1820 , and the second dump valve  1841  may be provided in the second bypass flow path  1840  to control the flow of the pressurized medium between the second pressure chamber  1340  and the reservoir  1100 . That is, the second bypass flow path  1840  may be connected by bypassing a front end and a rear end of the second dump check valve  1821  on the second dump flow path  1820 , and the second dump valve  1841  may be provided as a two-way solenoid valve that controls the flow of the pressurized medium between the second pressure chamber  1340  and the reservoir  1100 . The second dump valve  1841  may be provided as a normally open type solenoid valve that operates to be closed when an electrical signal is received from the ECU in a normally open state. 
     The auxiliary dump flow path  1850  may assist a communication between the first pressure chamber  1330  and the reservoir  110  through an auxiliary hydraulic port  1850   a.  Specifically, the auxiliary hydraulic port  1850   a  is connected to the auxiliary dump flow path  1850 , thereby may assist the flow of the pressurized medium between the first pressure chamber  1330  and the reservoir  110 . A sealing member  1350   b  is provided in front (the left side based on  FIG. 1 ) of the auxiliary hydraulic port  1850   a  to allow a supply of the pressurized medium from the auxiliary dump flow path  1850  to the first pressure chamber  1330  and block the flow of the pressurized medium in an opposite direction. Also, a sealing member  1350   c  is provided at rear (the right side based on  FIG. 1 ) of the auxiliary dump flow path  1850  to prevent the pressurized medium from leaking from the first pressure chamber  1330  to an outside of the cylinder block  1310 . 
     The hydraulic control unit  1400  may be provided to control a hydraulic pressure transferred to each of the wheel cylinders  20 , and the ECU is provided to control the hydraulic pressure supply device  1300  and various valves based on hydraulic pressure information and pedal displacement information. 
     The hydraulic control unit  1400  may include the first hydraulic circuit  1510  that controls the flow of the pressurized medium transferred to first and second wheel cylinders  21  and  22  among the four wheel cylinders  20 , and the second hydraulic circuit  1520  that controls the flow of the pressurized medium transferred to third and fourth wheel cylinders  23  and  24 . Also, the hydraulic control unit  1400  includes a plurality of flow paths and valves to control the hydraulic pressure transferred to the wheel cylinders  20  from the hydraulic pressure supply device  1300 . 
     The first hydraulic flow path  1401  may be provided to be in communication with the first pressure chamber  1330 , and the second hydraulic flow path  1402  may be 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 joined into a third hydraulic flow path  1403 , and then branched again to a fourth hydraulic flow path  1404  connected to the first hydraulic circuit  1510  and a fifth hydraulic flow path  1405  connected to the second hydraulic circuit  1520 . 
     A sixth hydraulic flow path  1406  may be provided to be in communication with the first hydraulic circuit  1510 , and a seventh hydraulic flow path  1407  may be provided to be in communication with the second hydraulic circuit  1520 . The sixth hydraulic flow path  1406  and the seventh hydraulic flow path  1407  may be joined into an eighth hydraulic flow path  1408 , and then branched again to a ninth hydraulic flow path  1409  communicating with the first pressure chamber  1330  and a tenth hydraulic flow path  1410  communicating with the second pressure chamber  1340 . 
     A first valve  1431  to control the flow of the pressurized medium may be provided on the first hydraulic flow path  1401 . The first valve  1431  may be provided as a check valve that allows only the flow of the pressurized medium discharged from the first pressure chamber  1330  and blocks the flow of the pressurized medium in an opposite direction. Also, a second valve  1432  to control the flow of the pressurized medium may be provided on the second hydraulic flow path  1402 . The second valve  1432  may be provided as a check valve that allows only the flow of the pressurized medium discharged from the second pressure chamber  1340  and blocks the flow of the pressurized medium in an opposite direction. 
     The fourth hydraulic flow path  1404  is branched from the third hydraulic flow path  1403  where the first hydraulic flow path  1401  and the second hydraulic flow path  1402  join, and is connected to the first hydraulic circuit  1510 . A third valve  1433  to control the flow of the pressurized medium may be provided on the fourth hydraulic flow path  1404 . The third valve  1433  may be provided as a check valve that allows only the flow of the pressurized medium from the third hydraulic flow path  1403  to the first hydraulic circuit  1510  and blocks the flow of the pressurized medium in an opposite direction. 
     The fifth hydraulic flow path  1405  is branched from the third hydraulic flow path  1403  where the first hydraulic flow path  1401  and the second hydraulic flow path  1402  join, and is connected to the second hydraulic circuit  1520 . A fourth valve  1434  to control the flow of the pressurized medium may be provided on the fifth hydraulic flow path  1405 . The fourth valve  1434  may be provided as a check valve that allows only the flow of the pressurized medium from the third hydraulic flow path  1403  to the second hydraulic circuit  1520  and blocks the flow of the pressurized medium in an opposite direction. 
     The sixth hydraulic flow path  1406  in communication with the first hydraulic circuit  1510  and the seventh hydraulic flow path  1407  in communication with the second hydraulic circuit  1520  are provided to join into the eighth hydraulic flow path  1408 . A fifth valve  1435  may be provided on the sixth hydraulic flow path  1406  to control the flow of the pressurized medium. The fifth valve  1435  may be provided as a check valve that allows only the flow of the pressurized medium discharged from the first hydraulic circuit  1510  and blocks the flow of the pressurized medium in an opposite direction. Also, a sixth valve  1436  may be provided on the seventh hydraulic flow path  1407  to control the flow of the pressurized medium. The sixth valve  1436  may be provided as a check valve that allows only the flow of the pressurized medium discharged from the second hydraulic circuit  1520  and blocks the flow of the pressurized medium in an opposite direction. 
     The ninth hydraulic flow path  1409  is branched from the eighth hydraulic flow path  1408  where the sixth hydraulic flow path  1406  and the seventh hydraulic flow path  1407  join, and is connected to the first pressure chamber  1330 . A seventh valve  1437  may be provided on the ninth hydraulic flow path  1409  to control the flow of the pressurized medium. The seventh valve  1437  may be provided as a two-way control valve that controls the flow of the pressurized medium delivered along the ninth hydraulic flow path  1409 . The seventh valve  1437  may be provided as a normally closed type solenoid valve that operates to be open when an electrical signal is received from the ECU in a normally closed state. 
     The tenth hydraulic flow path  1410  is branched from the eighth hydraulic flow path  1408  where the sixth hydraulic flow path  1406  and the seventh hydraulic flow path  1407  join, and is connected to the second pressure chamber  1340 . An eighth valve  1438  may be provided on the tenth hydraulic flow path  1410  to control the flow of the pressurized medium. The eighth valve  1438  may be provided as a two-way control valve that controls the flow of the pressurized medium delivered along the tenth hydraulic flow path  1410 . Like the seventh valve  1437 , the eighth valve  1438  may be provided as a normally closed type solenoid valve that operates to be open when an electrical signal is received from the ECU in a normally closed state. 
     Due to the above-described arrangement of the hydraulic flow paths and valves of the hydraulic control unit  1400 , 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 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 generated 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 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 . 
     By contrast, due to a negative pressure generated in the first pressure chamber  1330  by the backward movement of the hydraulic piston  1320 , the pressurized medium provided to the first hydraulic circuit  1510  may be recovered to the first pressure chamber  1330  by sequentially passing through the sixth hydraulic flow path  1406 , the eighth hydraulic flow path  1408  and the ninth hydraulic flow path  1409 , and also the pressurized medium provided to the second hydraulic circuit  1520  may be recovered to the first pressure chamber  1330  by sequentially passing through the seventh hydraulic flow path  1407 , the eighth hydraulic flow path  1408  and the ninth hydraulic flow path  1409 . Also, due to a negative pressure generated in the second pressure chamber  1340  by the forward movement of the hydraulic piston  1320 , the pressurized medium provided to the first hydraulic circuit  1510  may be recovered to the second pressure chamber  1340  by sequentially passing through the sixth hydraulic flow path  1406 , the eighth hydraulic flow path  1408  and the tenth hydraulic flow path  1410 , and also the pressurized medium provided to the second hydraulic circuit  1520  may be recovered to the second pressure chamber  1340  by sequentially passing through the seventh hydraulic flow path  1407 , the eighth hydraulic flow path  1408  and the tenth hydraulic flow path  1410 . 
     Also, due to the negative pressure generated in the first pressure chamber  1330  by the backward movement of the hydraulic piston  1320 , the pressurized medium may be supplied from the reservoir  110  to the first pressure chamber  1330  through the first dump flow path  1810 , and also due to the negative pressure generated in the second pressure chamber  1340  by the forward movement of the hydraulic piston  1320 , the pressurized medium may be supplied from the reservoir  110  to the second pressure chamber  1340  through the second dump flow path  1820 . 
     The delivery of the hydraulic pressure and negative pressure by the arrangement of the hydraulic flow paths and the valves will be described in greater detail with reference to  FIGS. 2 to 7 . 
     The first hydraulic circuit  1510  of the hydraulic control unit  1400  may control a hydraulic pressure in the first and second wheel cylinders  21  and  22 , i.e., the two cylinders  20  among the four wheels RR, RL, FR and FL, and the second hydraulic circuit  1520  may control a hydraulic pressure in the third and fourth wheel cylinders  23  and  24 , i.e., the other two wheel cylinders  20 . 
     The first hydraulic circuit  1510  may receive the hydraulic pressure through the fourth hydraulic flow path  1404 , and discharge the hydraulic pressure through the sixth hydraulic flow path  1406 . To this end, as shown in  FIG. 1 , the fourth hydraulic flow path  1404  and the sixth hydraulic flow path  1406  may be joined, and then branched to two flow paths connected to the first wheel cylinder  21  and the second wheel cylinder  22 . Also, the second hydraulic circuit  1520  may receive the hydraulic pressure through the fifth hydraulic flow path  1405 , and discharge the hydraulic pressure through the seventh hydraulic flow path  1407 . Accordingly, as shown in  FIG. 1 , the fifth hydraulic flow path  1405  and the seventh hydraulic flow path  1407  may be joined, and then branched to two flow paths connected to the third wheel cylinder  23  and the fourth wheel cylinder  24 . However, a flow path connection shown in  FIG. 1  is an example to help understanding, and the disclosure is not limited thereto. Each of the fourth hydraulic flow path  1404  and the sixth hydraulic flow path  1406  may be connected to the first hydraulic circuit  1510  side and independently branched and connected to the first wheel cylinder  21  and the second wheel cylinder  22 , and likewise, each of the fifth hydraulic flow path  1405  and the seventh hydraulic flow path  1407  may be connected to the second hydraulic circuit  1520  side and independently branched and connected to the third wheel cylinder  23  and the fourth wheel cylinder  24 . It should be understood to be the same even when the connection is made in various methods and structures. 
     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,  to control the flow and the hydraulic pressure of the pressurized medium transferred to the first to fourth wheel cylinders  20 . The first to fourth inlet valves  1511   a,    1511   b,    1521   a  and  1521   b  are disposed on an upstream side of the first to fourth wheel cylinders  20 , respectively, and may be provided as normally open type solenoid valves that operate to be closed when an electrical signal is received from the ECU 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 to the first to fourth inlet valves  1511   a,    1511   b,    1521   a  and  1521   b.  The first to fourth check valves  1513   a,    1513   b,    1523   a  and  1523   b  may be provided in bypass flow paths that connect front 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 . Also, the first to fourth check valves  1513   a,    1513   b,    1523   a  and  1523   b  may allow only the flow of the pressurized medium from the respective wheel cylinders  20  to the hydraulic pressure supply device  1300  and block the flow of the pressurized medium from the hydraulic pressure supply device  1300  to the wheel cylinders  20 . The hydraulic pressure of the pressurized medium applied to the respective wheel cylinders  20  may be quickly released by the first to fourth check valves  1513   a,    1513   b,    1523   a  and  1523   b.  Also, 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 respective wheel cylinders  20  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 branched from the first backup flow path  1610  to be descried later. The first backup flow path  1610  is provided with at least one first cut valve  1611  to control the flow of the pressurized medium between the integrated master cylinder  1200  and the first and second wheel cylinders  21  and  22 . Also, in an anti-lock braking system (ABS) braking mode of a vehicle, the first cut valve  1611  selectively releases the hydraulic pressure of the pressurized medium applied to the first and second wheel cylinders  21  and  22 , thereby may transfer the hydraulic pressure of the pressurized medium to the reservoir  1100  through the first backup flow path  1610 , the first simulation chamber  1240   a,  and the first simulation flow path  1260 . 
     The third and fourth wheel cylinders  23  and  24  of the second hydraulic circuit  1520  may be branched from the second backup flow path  1620  to be descried later. The second backup flow path  1620  is provided with at least one second cut valve  1621  to control the flow of the pressurized medium between the integrated master cylinder  1200  and the third and fourth wheel cylinders  23  and  24 . Also, in the ABS braking mode of the vehicle, the second cut valve  1621  selectively releases the hydraulic pressure of the pressurized medium applied to the third and fourth wheel cylinders  23  and  24 , thereby may transfer the hydraulic pressure of the pressurized medium to the reservoir  1100  through the second backup flow path  1620  and the second master chamber  1220   b.    
     The electronic brake system  1000  according to the first embodiment may include the first and second backup flow paths and the auxiliary backup flow path  1610 ,  1620  and  1630  to implement braking by directly supplying the pressurized medium discharged from the integrated master cylinder  1200  to the wheel cylinders  20 , when a normal operation may not be performed due to a device failure, or the like. An abnormal operation mode where the hydraulic pressure in the integrated master cylinder  1200  is directly transferred to the wheel cylinders  20  is referred to as a fallback mode. 
     The first backup flow path  1610  is provided to connect the first simulation chamber  1240   a  of the integrated master cylinder  1200  and the first hydraulic circuit  1510 , and the second backup flow path  1620  is provided to connect the second master chamber  1220   b  of the integrated master cylinder  1200  and the second hydraulic circuit  1520 . The auxiliary backup flow path  1630  is provided to connect the first master chamber  1220   a  of the integrated master cylinder  1200  and the first backup flow path  1610 . 
     Specifically, one end of the first backup flow path  1610  may be connected to the first simulation chamber  1240   a,  and another end thereof may be connected to downstream sides of the first inlet valve  1511   a  and the second inlet valve  1511   b  on the first hydraulic circuit  1510 . Also, one end of the second backup flow path  1620  may be connected to the second master chamber  1220   b,  and another end thereof may be connected to downstream sides of the third inlet valve  1521   a  and the fourth inlet valve  1521   b  on the second hydraulic circuit  1520 . Also, the auxiliary backup flow path  1630  is joined to be connect to the first backup flow path  1610 , but is not limited thereto. That is, the auxiliary backup flow path  1630  may be provided to connect the first simulation chamber  1240   a  and the first hydraulic circuit  1510  as a separate flow path. 
     The auxiliary backup flow path  1630  may include an orifice  1631  that may reduce a flow rate of the pressurized medium passing through the auxiliary backup flow path  1630 . Accordingly, in a diagnosis mode to be described later, the pressurized medium transferred from the first hydraulic circuit  1510  to the integrated master cylinder  1200  may be filled in the first simulation chamber  1240   a  before the first master chamber  1220   a,  which will be described in detail later. 
     The first and second backup flow paths  1610  and  1620  may include at least one first and second cut valves  1611  and  1621 , respectively, to control the bidirectional flow and hydraulic pressure of the pressurized medium transferred to the first to fourth wheel cylinders  20 . Specifically, the first backup flow path  1610  may be branched to be connected to the first and second wheel cylinders  21  and  22 , and a pair of first cut valves  1611  may be provided in each of the first and second wheel cylinders  21  and  22 . Also, the second backup flow path  1620  may be branched to be connected to the third and fourth wheel cylinders  23  and  24 , and a pair of second cut valves  1621  may be provided in each of the third and fourth wheel cylinders  23  and  24 . 
     The first and second cut valves  1611  and  1621  may be provided as a normally open type solenoid valve that operates to be closed when an electrical signal is received from the ECU in a normally open state. 
     Accordingly, in a normal braking mode, when the first and second cut valves  1611  and  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 wheel cylinders  20  through the hydraulic control unit  1400  to perform braking. By contrast, in an abnormal operation mode, the first and second cut valves  1611  and  1621  are open, and thus the pressurized medium pressurized in the integrated master cylinder  1200  may be directly supplied to the wheel cylinders  20  through the backup flow paths  1610 ,  1620  and  1630  to perform braking. 
     The electronic brake system  1000  according to the first embodiment of the disclosure may include a pressure sensor (PS) for detecting at least one hydraulic pressure in the first hydraulic circuit  1510  and the second hydraulic circuit  1520 . Although it is illustrated that the pressure sensor is provided on the first hydraulic circuit  1510  side, a position and the number of pressure sensors are not limited thereto. As long as the pressure sensor may detect a hydraulic pressure of the hydraulic circuit and the integrated master cylinder  1200 , the position and the number thereof may vary. 
     Hereinafter, an operation method of the electronic brake system  1000  according to the first embodiment of the disclosure is described. 
     Operations of the electronic brake system  1000  according to the first embodiment of the disclosure may include a normal operation mode, an abnormal operation mode (fallback mode), an ABS dump mode, and a diagnosis mode. In the normal operation mode, various devices and valves of the electronic brake system  1000  operate normally without failure or error, and in the abnormal operation mode, the electronic brake system  1000  operates abnormally due to failure or error of various devices and valves. In the ABS dump mode, a hydraulic pressure in the wheel cylinders  20  is rapidly and continuously decompressed for ABS operation, and in the diagnosis mode, whether a leak occurs in the integrated master cylinder  1200  or the simulator valve  1261  is checked. 
     First, the normal operation mode among the operation methods of the electronic brake system  1000  according to the first embodiment of the disclosure is described. 
     The normal operation mode of the electronic brake system  1000  according to the first embodiment of the disclosure may be divided into first to third braking modes, as the hydraulic pressure transferred from the hydraulic pressure supply device  1300  to the wheel cylinders  20 . Specifically, in the first braking mode, the hydraulic pressure by the hydraulic pressure supply device  1300  may be primarily provided to the wheel cylinders  20 , and in the second braking mode, the hydraulic pressure by the hydraulic pressure supply device  1300  may be secondarily provided to the wheel cylinders  20  to transfer a higher braking pressure than in the first braking mode. In the third braking mode, the hydraulic pressure by the hydraulic pressure supply device  1300  may be thirdly provided to the wheel cylinders  20  to transfer a higher braking pressure than in the second braking mode. 
     The first to third braking modes may be changed by changing 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 pressurized medium without a high specification motor by utilizing the first to third braking modes, and further, may prevent unnecessary loads applied to the motor. Accordingly, 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 first embodiment of the disclosure performs a first braking mode. 
     Referring to  FIG. 2 , when the driver depresses the brake pedal  10  at a beginning of the braking, the motor (not shown) operates to rotate in one direction, the rotational force of the motor is transferred to the hydraulic pressure supply device  1300  by the power transfer unit, and the hydraulic piston  1320  of the hydraulic pressure supply device  1300  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 each of the 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 and second wheel cylinders  21  and  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 . In this instance, because the first valve  1431  is a check valve allowing only the flow of the pressurized medium discharged from the first pressure chamber  1330  and the third valve  1433  is a check valve allowing only the flow of the pressurized medium from the third hydraulic flow path  1403  to the first hydraulic circuit  1510 , 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 cut valves  1611  are maintained in a closed state, and thus the hydraulic pressure of the pressurized medium may be prevented from leaking to the reservoir  1100 . 
     Also, 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 , the third hydraulic flow path  1403  and the fifth hydraulic flow path  1405 . As described above, because the first valve  1431  is a check valve allowing only the flow of the pressurized medium discharged from the first pressure chamber  1330  and the fourth valve  1434  is a check valve allowing only the flow of the pressurized medium from the third hydraulic flow path  1403  to the second hydraulic circuit  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 second cut valves  1621  are maintained in a closed state, and thus the hydraulic pressure of the pressurized medium may be prevented from leaking to the second backup flow path  1620 . 
     The eighth valve  1438  is controlled in the closed state in the first braking mode, and thus the hydraulic pressure generated in the first pressure chamber  1330  may be prevented from leaking to the second pressure chamber  1340 . Also, the first dump valve  1831  provided in the first bypass flow path  1830  is maintained in the closed state, and thus the hydraulic pressure generated in the first pressure chamber  1330  may be prevented from leaking to the reservoir  1100 . 
     Meanwhile, a negative pressures is generated in the second pressure chamber  1340  as the hydraulic piston  1320  moves forward, the hydraulic pressure of the pressurized medium is transferred to the second pressure chamber  1340  from the reservoir  1100  through the second dump flow path  1820  and the second bypass flow path  1840 , and thus the second braking mode to be described later may be prepared. Because the second dump check valve  1821  provided in the second dump flow path  1820  allows the flow of the pressurized medium from the reservoir  1100  to the second pressure chamber  1340 , the pressurized medium may be stably supplied to the second pressure chamber  1340 . The second dump valve  1841  provided in the second bypass flow path  1840  is switched to an open state, and thus the pressurized medium may be rapidly supplied to the first pressure chamber  1330  from the reservoir  1100 . 
     In the first braking mode where braking of the wheel cylinders  20  is performed by the hydraulic pressure supply device  1300 , the first cut valves  1611  and the second cut valves  1621  provided in the first backup flow path  1610  and the second backup flow path  1620 , respectively, are switched to the closed state, the reservoir valve  1711  provided in the first reservoir flow path  1710  is switched to the closed state, and thus the pressurized medium discharged from the integrated master cylinder  1200  may be prevented from being delivered to the wheel cylinders  20 . 
     Specifically, when the pressing force is applied to the brake pedal  10 , the first master chamber  1220   a  is sealed because the first cut valves  1611  are closed, the second master chamber  1220   b  is sealed because the second cut valves  1621  are closed, and the second simulation chamber  1230   a  is sealed because the reservoir valve  1711  is closed. Accordingly, as the pressing force is applied to the brake pedal  10 , the first master chamber  1220   a,  the second master chamber  1220   b  and the second simulation chamber  1230   a  are sealed, and thus the second simulation piston  1230  and the master piston  1220  are not displaced. On the other hand, because the simulator valve  1261  is open so that the first simulation chamber  1240   a  and the reservoir  1100  are in communication with each other, the pressurized medium accommodated in the first simulation chamber  1240   a  is supplied to the reservoir  1100  through the simulation flow path  1260 , and the first simulation piston  1240  smoothly moves forward by the pressing force of the brake pedal  10  to generate displacement. As such, as the first simulation piston  1240  moves forward in a state where the second simulation piston  1230  is fixed, the elastic member  1250  disposed between the first simulation piston  1240  and the second simulation piston  1230  is compressed, and a reaction force corresponding to the pressing force of the brake pedal  10  acts by elastic restoring force of the compressed elastic member  1250 , thereby providing a stable and proper pedal feeling to the driver. 
     The electronic brake system  1000  according to the first embodiment of the disclosure may switch from the first braking mode to the second braking mode illustrated in  FIG. 3 , when a higher braking pressure than in the first braking mode is required to be provided. 
       FIG. 3  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the first embodiment of the disclosure performs a second braking mode. 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 reference, or when a hydraulic pressure detected by the pressure sensor is higher than a preset reference, the ECU may switch from the first braking mode to the second braking mode by determining that a higher braking pressure is required. 
     When switching from the first braking mode to the second braking mode, the motor operates to rotate in another direction, and the rotational force of the motor is transferred by the power transfer unit to the hydraulic pressure providing 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 each of the wheel cylinders  20  through the hydraulic control unit  1400 , the first hydraulic circuit  1510  and the second hydraulic circuit  1520  to generate a braking force. 
     Specifically, the hydraulic pressure generated in the second pressure chamber  1340  is secondarily transferred to the first and second wheel cylinders  21  and  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 . In this instance, because the second valve  1432  provided in the second hydraulic flow path  1402  is a check valve allowing only the flow of the pressurized medium discharged from the second pressure chamber  1340  and the third valve  1433  provided in the fourth hydraulic flow path  1404  is a check valve allowing only the flow of the pressurized medium from the third hydraulic flow path  1403  to the first hydraulic circuit  1510 , 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, the first cut valves  1611  are maintained in the closed state, and thus the hydraulic pressure of the pressurized medium may be prevented from leaking to the reservoir  1100 . 
     Also, the hydraulic pressure generated in the second pressure chamber  1340  is secondarily transferred to the third and fourth wheel cylinders  23  and  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 described above, because the second valve  1432  provided in the second hydraulic flow path  1402  is a check valve allowing only the flow of the pressurized medium discharged from the second pressure chamber  1340  and the fourth valve  1434  provided in the fifth hydraulic flow path  1405  is a check valve allowing only the flow of the pressurized medium from the third hydraulic flow path  1403  to the second hydraulic circuit  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 the open state and the second cut valves  1621  are maintained in the closed state, and thus the hydraulic pressure of the pressurized medium may be prevented from leaking to the second backup flow path  1620 . 
     The seventh valve  1437  is controlled in a closed state in the second braking mode, and thus the hydraulic pressure generated in the second pressure chamber  1340  may be prevented from leaking to the first pressure chamber  1330 . Also, the second dump valve  1841  is switched to a closed state, and thus the hydraulic pressure generated in the second pressure chamber  1340  may be prevented from leaking to the reservoir  1100 . 
     Meanwhile, a negative pressures is generated in the first pressure chamber  1330  as the hydraulic piston  1320  moves backward, the hydraulic pressure of the pressurized medium is transferred to the first pressure chamber  1330  from the reservoir  1100  through the first dump flow path  1810  and the first bypass flow path  1830 , and thus the third braking mode to be described later may be prepared. Because the first dump check valve  1811  provided in the first dump flow path  1810  allows the flow of the pressurized medium from the reservoir  1100  to the first pressure chamber  1330 , the pressurized medium may be stably supplied to the first pressure chamber  1330 . The first dump valve  1831  provided in the first bypass flow path  1830  is switched to an open state, and thus the pressurized medium may be rapidly supplied to the first pressure chamber  1330  from the reservoir  1100 . 
     Because the operation of the integrated master cylinder  1200  in the second braking mode is the same as that of the integrated master cylinder  1200  in the first braking mode described above, a description thereof is omitted to prevent duplication of content. 
     The electronic brake system  1000  according to the first embodiment of the disclosure may switch from the second braking mode to the third braking mode illustrated in  FIG. 4 , when a higher braking pressure than in the second braking mode is required to be provided. 
       FIG. 4  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the first embodiment of the disclosure 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 reference, or when a hydraulic pressure detected by the pressure sensor is higher than a preset reference, the ECU may switch from the second braking mode to the third braking mode by determining that a higher braking pressure is required. 
     When switching from the second braking mode to the third braking mode, the motor (not shown) operates to rotate in one direction, and the rotational force of the motor is transferred by the power transfer unit to the hydraulic pressure providing 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 each of the wheel cylinders  20  through the hydraulic control unit  1400 , the first hydraulic circuit  1510  and the second hydraulic circuit  1520  to generate a braking force. 
     Specifically, a portion of the hydraulic pressure generated in the first pressure chamber  1330  is primarily transferred to the first and second wheel cylinders  21  and  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 . In this instance, because the first valve  1431  is a check valve allowing only the flow of the pressurized medium discharged from the first pressure chamber  1330  and the third valve  1433  is a check valve allowing only the flow of the pressurized medium from the third hydraulic flow path  1403  to the first hydraulic circuit  1510 , 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 cut valves  1611  are maintained in the closed state, and thus the hydraulic pressure of the pressurized medium may be prevented from leaking to the reservoir  1100 . 
     Also, a portion of 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 , the third hydraulic flow path  1403  and the fifth hydraulic flow path  1405 . As described above, because the first valve  1431  is a check valve allowing only the flow of the pressurized medium discharged from the first pressure chamber  1330  and the fourth valve  1434  is a check valve allowing only the flow of the pressurized medium from the third hydraulic flow path  1403  to the second hydraulic circuit  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 the open state and the second cut valves  1621  are maintained in the closed state, and thus the hydraulic pressure of the pressurized medium may be prevented from leaking to the second backup flow path  1620 . 
     Meanwhile, because a high hydraulic pressure is provided in the third braking mode, as the hydraulic piston  1320  moves forward, the hydraulic pressure in the first pressure chamber  1330  also increases a force to move the hydraulic piston  1320  backward, and thus a load applied to the motor drastically increases. Accordingly, in the third braking mode, the seventh valve  1437  and the eighth valve  1438  operate to be open to allow the flow of the pressurized medium through the ninth hydraulic flow path  1409  and the tenth hydraulic flow path  1410 . That is, a portion 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 ninth hydraulic flow path  1409  and the tenth hydraulic flow path  1410 , 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. Accordingly, the load applied to the motor may be reduced and durability and reliability of devices may be improved. 
     In the third braking mode, the first dump valve  1831  is switched to the closed state, and thus the hydraulic pressure generated in the first pressure chamber  1330  may be prevented from leaking to the reservoir  1100  along the first bypass flow path  1830 . Also, the second dump valve  1841  is controlled in the closed state, and thus a negative pressure may be rapidly generated in the second pressure chamber  1340  by the forward movement of the hydraulic piston  1320  and the pressurized medium provided from the first pressure chamber  1330  may be smoothly supplied. 
     Because the operation of the integrated master cylinder  1200  in the third braking mode is the same as that of the integrated master cylinder  1200  in the first and second braking modes described above, a description thereof is omitted to prevent duplication of content. 
     Hereinafter, a method of operating the electronic brake system  1000  according to the first embodiment of the disclosure in which braking is released from the normal operation mode is described. 
       FIG. 5  is a hydraulic circuit diagram illustrating that the hydraulic piston  1320  of the electronic brake system  1000  according to the first embodiment of the disclosure moves backward to release the third 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 transfer unit, and the power transfer unit moves the hydraulic piston  1320  backward. Accordingly, the hydraulic pressure in the first pressure chamber  1330  may be released and at the same time, a negative pressure may be generated. Thus, the pressurized medium in the wheel cylinders  20  may be delivered 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 sixth hydraulic flow path  1406 , the eighth hydraulic flow path  1408  and the ninth hydraulic flow path  1409 . In this instance, because the fifth valve  1435  provided in the sixth hydraulic flow path  1406  is a check valve allowing only the flow of the pressurized medium discharged from the first hydraulic circuit  1510 , the pressurized medium may be recovered, and the seventh valve  1437  is open to allow the flow of the pressurized medium through the ninth hydraulic flow path  1409 . Also, the first dump valve  1831  is operated to be closed so that a negative pressure is effectively generated in the first pressure chamber  1330 . 
     At the same time, in order to enable the hydraulic piston  1320  to move backward rapidly and smoothly, the pressurized medium accommodated in the second pressure chamber  1340  is transferred to the first pressure chamber  1330  by sequentially passing through the tenth hydraulic flow path  1410  and the ninth hydraulic flow path  1409 . To this end, the eighth valve  1438  provided in the tenth hydraulic flow path  1410  is also switched to the open state. In this instance, the second dump valve  1841  operates to be closed, thereby may induce the pressurized medium of the second pressure chamber  1340  to be supplied to the first pressure chamber  1330 . 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 cut valves  1611  are maintained in the closed state. 
     Also, the hydraulic pressure of the pressurized medium applied to the third and fourth wheel cylinders  23  and  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 seventh hydraulic flow path  1407 , the eighth hydraulic flow path  1408  and the ninth hydraulic flow path  1409 . As described above, because the sixth valve  1436  provided in the seventh hydraulic flow path  1407  is a check valve allowing only the flow of the pressurized medium discharged from the second hydraulic circuit  1520 , the pressurized medium may be recovered, and the seventh valve  1437  is open to allow the flow of the pressurized medium through the ninth hydraulic flow path  1409 . 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 valves  1621  are maintained in the closed state. 
     After the releasing of the third braking mode is completed, it may be switched to the releasing operation of the second braking mode illustrated in  FIG. 6  in order to further lower the braking pressure of the wheel cylinders. 
       FIG. 6  is a hydraulic circuit diagram illustrating that the hydraulic piston  1320  of the electronic brake system  1000  according to the first embodiment of the disclosure moves forward to release the second braking mode. 
     Referring to  FIG. 6 , 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 transfer unit, and the power transfer unit moves the hydraulic piston  1320  forward. Accordingly, the hydraulic pressure in the second pressure chamber  1340  may be released and at the same time, a negative pressure may be generated. Thus, the pressurized medium in the wheel cylinders  20  may be delivered to the second pressure chamber  1340 . 
     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 second pressure chamber  1340  by sequentially passing through the sixth hydraulic flow path  1406 , the eighth hydraulic flow path  1408  and the tenth hydraulic flow path  1410 . In this instance, because the fifth valve  1435  provided in the sixth hydraulic flow path  1406  allows only the flow of the pressurized medium discharged from the first hydraulic circuit  1510 , the pressurized medium may be recovered, and the eighth valve  1438  provided in the tenth hydraulic flow path  1410  is switched to be open to allow the flow of the pressurized medium delivered along the tenth hydraulic flow path  1410 . Also, the seventh valve  1437  is controlled in the closed state so that the pressurized medium recovered from the first hydraulic circuit  1510  may be prevented from leaking to the first pressure chamber  1330  through the ninth hydraulic flow path  1409 . 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 cut valves  1611  are maintained in the closed state. 
     Also, the hydraulic pressure of the pressurized medium applied to the third and fourth wheel cylinders  23  and  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 seventh hydraulic flow path  1407 , the eighth hydraulic flow path  1408  and the tenth hydraulic flow path  1410 . As described above, because the sixth valve  1436  provided in the seventh hydraulic flow path  1407  allows the flow of the pressurized medium discharged from the second hydraulic circuit  1520  and the eighth valve  1438  provided in the tenth hydraulic flow path  1410  is open, the pressurized medium may be smoothly recovered to the second pressure chamber  1340 . Further, the seventh valve  1437  is controlled in the closed state, the pressurized medium recovered from the first hydraulic circuit  1510  may be prevented from leaking to the first pressure chamber  1330  through the ninth hydraulic flow path  1409 . 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 valves  1621  are maintained in the closed state. 
     Meanwhile, when the second braking mode is released, the first dump valve  1831  is open for smooth forward movement of the hydraulic piston  1320  and the second dump valve  1841  may be switched to the closed state to rapidly generate a negative pressure in the second pressure chamber  1340 . 
     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. 7  in order to completely release the braking pressure applied to the wheel cylinders  20 . 
       FIG. 7  is a hydraulic circuit diagram illustrating that the hydraulic piston  1320  of the electronic brake system  1000  according to the first embodiment of the disclosure moves backward again to release the first braking mode. 
     Referring to  FIG. 7 , 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 transfer unit, and the power transfer unit moves the hydraulic piston  1320  backward. Accordingly, a negative pressure may be generated in the first pressure chamber  1330 , and thus, the pressurized medium in the wheel cylinders  20  may be delivered 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 sixth hydraulic flow path  1406 , the eighth hydraulic flow path  1408  and the ninth hydraulic flow path  1409 . In this instance, because the fifth valve  1435  provided in the sixth hydraulic flow path  1406  is a check valve allowing only the flow of the pressurized medium discharged from the first hydraulic circuit  1510 , the pressurized medium may be recovered, and the seventh valve  1437  is open to allow the flow of the pressurized medium through the ninth hydraulic flow path  1409 . 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 cut valves  1611  are maintained in the closed state. Also, the eighth valve  1438  is controlled in the closed state so that the pressurized medium recovered from the first hydraulic circuit  1510  may be prevented from leaking to the second pressure chamber  1340  through the tenth hydraulic flow path  1410 , and the first dump valve  1831  is operated to be closed so that a negative pressure is effectively generated in the first pressure chamber  1330 . 
     The hydraulic pressure of the pressurized medium applied to the third and fourth wheel cylinders  23  and  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 seventh hydraulic flow path  1407 , the eighth hydraulic flow path  1408  and the ninth hydraulic flow path  1409 . As described above, because the sixth valve  1436  provided in the seventh hydraulic flow path  1407  is a check valve allowing only the flow of the pressurized medium discharged from the second hydraulic circuit  1520 , the pressurized medium may be recovered, and the seventh valve  1437  is open to allow the flow of the pressurized medium through the ninth hydraulic flow path  1409 . 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. Further, the eighth valve  1438  is controlled in the closed state so that the pressurized medium recovered from the second hydraulic circuit  1520  may be prevented from leaking to the second pressure chamber  1340  through the tenth hydraulic flow path  1410 . 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 valves  1621  are maintained in the closed state. 
     At the same time, the second dump valve  1841  is open for smooth backward movement of the hydraulic piston  1320 , and thus the pressurized medium accommodated in the second pressure chamber  1340  may be discharged to the reservoir  1100  through the second bypass flow path  1840 . 
     Hereinafter, an operation state when the electronic brake system  1000  according to the first embodiment of the disclosure does not operate normally, i.e., a fallback mode, is described. 
       FIG. 8  is a hydraulic circuit diagram illustrating an operation in an abnormal operation mode (fallback mode) where the electronic brake system  1000  according to the first embodiment of the disclosure may not operate normally due to a failure of device, and the like. 
     Referring to  FIG. 8 , in the abnormal operation mode, each of the valves is controlled to be in an initial braking state which is a non-operating state. In this instance, when the driver depresses the brake pedal  10 , the first simulation piston  1240  connected to the brake pedal  10  moves forward, and thus displacement occurs. Because the first simulator valve  1261  is closed and the first cut valves  1611  are maintained in an open state, the pressurized medium accommodated in the first simulation chamber  1240   a  may be delivered to the first and second wheel cylinders  21  and  22  in the first hydraulic circuit  1510  through the first backup flow path  1610  by the forward movement of the first simulation piston  1240  to perform braking. 
     Also, when the first simulation piston  1240  moves forward, the second simulation chamber  1230   a  and the first master chamber  1220   a  are not sealed, and thus the elastic member  1250  is not compressed and the second simulation piston  1230  moves forward and displacement occurs. In this instance, because the reservoir valve  1711  is maintained in an open state, the pressurized medium accommodated in the second simulation chamber  1230   a  may be delivered to the reservoir  1100  through the first reservoir flow path  1710  by the displacement of the second simulation piston  1230 . Because the first cut valves  1611  are maintained in the open state, the pressurized medium accommodated in the first master chamber  1220   a  may be delivered to the first and second wheel cylinders  21  and  22  in the first hydraulic circuit  1510  through the auxiliary backup flow path  1630  the first backup flow path  1610  to perform braking. As the second simulation piston  1230  moves forward, the cut-off hole  1231  provided in the second simulation piston  1230  blocks a connection between the first master chamber  1220   a  and the second reservoir flow path  1720  in order to prevent the pressurized medium accommodated in the first master chamber  1220   a  from being delivered to the reservoir  1100 . 
     Also, when the second simulation piston  1230  moves forward, the pressurized medium in the first master chamber  1220   a  moves the master piston  1220  forward and displacement occurs. Because the second cut valves  1621  are maintained in an open state, the pressurized medium accommodated in the second master chamber  1220   b  may be delivered to the third and fourth wheel cylinders  23  and  24  in the second hydraulic circuit  1520  through the second backup flow path  1620  to perform braking. In this instance, as the master piston  1220  moves forward, the cut-off hole  1221  provided in the master piston  1220  blocks a connection between the second master chamber  1220   b  and the third reservoir flow path  1730  in order to prevent the pressurized medium from being delivered to the reservoir  1100 . 
     In the abnormal operation mode, because the first cut valves  1611 , the second cut valves  1621  and the reservoir valve  1711  are in the open state and the first simulator valve  1261  is in the closed state, the hydraulic pressure transferred from the first simulation chamber  1240   a,  the first master chamber  1220   a  and the second master chamber  1220   b  of the integrated master cylinder  1200  may be directly transferred to each of the wheel cylinders  20 , thereby improving a braking stability and performing quick braking. 
     Hereinafter, an ABS dump mode of the electronic brake system  1000  according to the first embodiment of the disclosure is described. 
       FIG. 9  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the first embodiment of the disclosure operates in the ABS dump mode. 
     Referring to  FIG. 9 , when the ABS dump mode is to be performed while the hydraulic pressure supply device  1300  is operating, the ECU may be operated to control operations of the first and second cut valves  1611  and  1621  for braking. 
     Specifically, as the hydraulic piston  1320  of the hydraulic pressure supply device  1300  moves forward, a hydraulic pressure is generated in the first pressure chamber  1330 , and the hydraulic pressure in the first pressure chamber  1330  is delivered to each of the 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. Afterwards, when the ABS dump mode is to be performed, the ECU repeatedly opens and closes at least a portion of the first cut valves  1611 , so that a portion of the hydraulic pressure of the pressurized medium applied to the first and second wheel cylinders  21  and  22  may be discharged to the reservoir  1100  by sequentially passing through the first backup flow path  1610 , the first simulation chamber  1240   a  and the first simulation flow path  1260 . Also, the ECU repeatedly opens and closes at least a portion of the second cut valves  1621 , so that a portion of the hydraulic pressure of the pressurized medium applied to the third and fourth wheel cylinders  23  and  24  may be discharged to the reservoir  1100  by sequentially passing through the second backup flow path  1620 , the second master chamber  1220   b  and the third reservoir flow path  1730 . 
     Hereinafter, a diagnosis mode of the electronic brake system  1000  according to the first embodiment of the disclosure is described. 
     The electronic brake system  1000  according to the first embodiment of the disclosure may perform the diagnosis mode for checking whether a leak occurs in the integrated master cylinder  1200 .  FIG. 10  is a hydraulic circuit diagram illustrating that the electronic brake system  1000  according to the first embodiment of the disclosure operates in the diagnosis mode. Referring to  FIG. 10 , when the diagnosis mode is performed, the ECU controls the hydraulic pressure generated in the hydraulic pressure supply device  1300  to be supplied to the first simulation chamber  1240   a  of the integrated master cylinder  1200 . 
     Specifically, in a state where each of the valves is controlled to be in the initial braking state which is a non-operating state, the ECU operates to move the hydraulic piston  1320  forward to generate a hydraulic pressure in the first pressure chamber  1330 , and at the same time, controls the second cut valves  1621  to be in the closed state. The hydraulic pressure generated in the first pressure chamber  1330  is 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 . Also, the pressurized medium delivered to the first hydraulic circuit  1510  is delivered to the first simulation chamber  1240   a  through the first backup flow path  1610  by opening at least a portion of the first cut valves  1611 . 
     In this instance, because the orifice  1631  provided in the auxiliary backup flow path  1630  slows down the delivery of the pressurized medium, the hydraulic pressure may be applied to the first simulation chamber  1240   a  first, and thus the second simulation piston  1230  may slightly move forward. Also, in order to move the second simulation piston  1230  forward even when the hydraulic pressure is applied to the first simulation chamber  1240   a  first, the reservoir valve  1711  is briefly open and then closed, the hydraulic pressure of the second simulation chamber  1230   a  is partially released, and thereby may move the second simulation piston  1230  forward. As described above, when the second simulation piston  1230  moves forward, the cut-off hole  1231  and the fourth hydraulic port  1280   d  are out of joint and blocked, and thus the first master chamber  1220   a  may be sealed. 
     Also, the first simulator valve  1261  remains closed, and thus the first simulation chamber  1240   a  may remain sealed. 
     Meanwhile, for quick diagnosis, the first inlet valve  1511   a  and the second inlet valve  1511   b  provided in the first hydraulic circuit  1510  may be switched to the closed state. 
     In this state, by comparing a hydraulic pressure value of the pressurized medium expected to be generated by the displacement of the hydraulic piston  1320  with a hydraulic pressure value of the first simulation chamber  1240   a  or the first hydraulic circuit  1510  measured by the pressure sensor (PS), a leak of the integrated master cylinder  1200  or the first simulator valve  1261  may be diagnosed. Specifically, an estimated 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 of the first simulation chamber  1240   a  or the first hydraulic circuit  1510  measured by the pressure sensor (PS), and when the two hydraulic pressure values are the same, it may be determined that no leak occurs in the integrated master cylinder  1200  or the first simulator valve  1261 . By contrast, when the actual hydraulic pressure value of the first simulation chamber  1240   a  or the first hydraulic circuit  1510  measured by the pressure sensor is lower than the estimated 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), which indicates that a portion of the hydraulic pressure of the pressurized medium applied to the first simulation chamber  1240   a  is lost, and thus it may be determined that a leak occurs in the integrated master cylinder  1200  or the first simulator valve  1261 , and this may be notified to the driver. 
     Hereinafter, an electronic brake system  2000  according to a second embodiment of the disclosure is described. 
     Also, in the description of the electronic brake system  2000  according to the second embodiment of the disclosure to be described below, except for additionally making a description using separate reference numerals, since the electronic brake system  2000  according to the second embodiment of the disclosure is the same as the electronic brake system  1000  according to the first embodiment of the disclosure, a description thereof is omitted to prevent duplication of content. 
     Recently, as the market demand for eco-friendly vehicles increases, hybrid vehicles with improved fuel efficiency are gaining popularity. A hybrid vehicle recovers kinetic energy as electrical energy while braking, stores it in a battery, and uses a motor as an auxiliary driving source of the vehicle. In general, a hybrid vehicle recovers energy by a generator (not shown), or the like, while braking to increase an energy recovery rate, which is called a regenerative braking mode. In the electronic brake system  2000  according to the second embodiment of the disclosure, a generator (not shown) may be provided in the third and fourth wheel cylinders  23  and  24  of the second hydraulic circuit  1520  to implement the regenerative braking mode. The regenerative braking mode may be implemented through cooperative control of the generator of the third and fourth wheel cylinders  23  and  24  and a fourth valve  2434 , which is described with reference to  FIG. 11 . 
       FIG. 11  is a hydraulic circuit diagram illustrating the electronic brake system  2000  according to the second embodiment of the disclosure. Referring to  FIG. 11 , the fourth valve  2434  may be provided in the fifth hydraulic flow path  1405  according to the second embodiment of the disclosure to control the flow of the pressurized medium. The fourth valve  2434  may be provided as a two-way control valve that controls the flow of the pressurized medium delivered along the fifth hydraulic flow path  1405 . The fourth valve  2434  may be provided as a normally closed type solenoid valve that operates to be open when an electrical signal is received from the ECU in a normally closed state. A fifth valve  2415  is controlled to be open in the normal operation mode, but when entering the regenerative braking mode by the generator (not shown) provided in the third and fourth wheel cylinders  23  and  24 , the fifth valve  2415  may be switched to a closed state. 
     Hereinafter, the regenerative braking mode of the electronic brake system  2000  according to the second embodiment of the disclosure is described. 
       FIG. 12  is a hydraulic circuit diagram illustrating that the electronic brake system  2000  according to the second embodiment of the disclosure operates in a regenerative braking mode. Referring to  FIG. 12 , in the first and second wheel cylinders  21  and  22  of the first hydraulic circuit  1510 , a braking force desired by a driver is formed by the hydraulic pressure of the pressurized medium by an operation of the hydraulic pressure supply device  1300  only. However, in the third and fourth wheel cylinders  23  and  24  of the second hydraulic circuit  1520  where an energy recovery device such as the generator, etc., is installed, a sum of braking pressures obtained by adding a braking pressure of the pressurized medium by the hydraulic pressure supply device  1300  and a regenerative braking pressure by the generator is required to be the same as a total braking force of the first and second wheel cylinders  21  and  22 . Accordingly, when entering the regenerative braking mode, a 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 , by removing or constantly maintaining a braking pressure applied to the third and fourth wheel cylinders  23  and  24  by the hydraulic pressure supply device  1300  through closing of the fourth valve  2434 , and at the same time, by increasing the regenerative braking pressure by the generator. 
     Specifically, referring to  FIG. 10 , when the driver depresses the brake pedal  10  in the first braking mode, the motor operates to rotate in one direction, the rotational force of the motor is transferred to the hydraulic pressure supply device  1300  by the power transfer unit, and the hydraulic piston  1320  of the hydraulic pressure supply device  1300  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 each of the 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 first hydraulic circuit  1510  where the energy recovery device such as the generator, etc., is not installed, the hydraulic pressure of the pressurized medium generated in the first pressure chamber  1330  is transferred to the first and second wheel cylinders  21  and  22  by sequentially passing through the first hydraulic flow path  1401 , the third hydraulic flow path  1403  and the fourth hydraulic flow path  1404  to perform braking of the first and second wheel cylinders  21  and  22 . 
     By contrast, in the second hydraulic circuit  1520  where the generator is installed, when the ECU determines to enter the regenerative braking mode by detecting a speed, a deceleration, etc., of the vehicle, the ECU may block the hydraulic pressure of the pressurized medium from being delivered to the third and fourth wheel cylinders  23  and  24  by closing the fourth valve  2434 , thereby implementing a regenerative braking by the generator. Afterwards, when the ECU determines that the vehicle is in an unsuitable state for regenerative braking or a braking pressure of the first hydraulic circuit  1510  is different from that of the second hydraulic circuit  1520 , the ECU may switch the fourth valve  2434  to an open state and control the hydraulic pressure of the pressurized medium to be delivered to the second hydraulic circuit  1520 , and at the same time, may synchronize the braking pressure of the first hydraulic circuit  1510  with the braking pressure of the second hydraulic circuit  1520 . Accordingly, the braking pressure or the braking force applied to the first to fourth wheel cylinders  21 ,  22 ,  23  and  24  may be evenly controlled, and thus oversteering or understeering may be prevented and a braking stability and a driving stability of the vehicle may be improved. 
     Hereinafter, an electronic brake system  3000  according to a third embodiment of the disclosure is described. 
     Also, in the description of the electronic brake system  3000  according to the third embodiment of the disclosure to be described below, except for additionally making a description using separate reference numerals, since the electronic brake system  3000  according to the third embodiment of the disclosure is the same as the electronic brake system  1000  according to the first embodiment of the disclosure, a description thereof is omitted to prevent duplication of content. 
       FIG. 13  is a hydraulic circuit diagram illustrating the electronic brake system  3000  according to the third embodiment of the disclosure. Referring to  FIG. 13 , an integrated master cylinder  3200  may further include a second simulation flow path  3270  that connects the first simulation chamber  1240   a  and the second simulation chamber  1230   a.  However, the second simulation flow path  3270  is not limited thereto, and may be provided to connect the first simulation flow path  1260  and the first reservoir flow path  1710 , and more specifically, may have one end connected between the integrated master cylinder  3200  and the first simulator valve  1261  of the first simulation flow path  1260  and another end connected between the integrated master cylinder  3200  and a reservoir valve  3711  of the first reservoir flow path  1260 . A second simulator valve  3271  may be provided in the second simulation flow path  3270  as a two-way control valve to control a flow of a braking fluid delivered through the second simulation flow path  3270 . The second simulator valve  3271  may be provided as a normally open type solenoid valve that operates to be closed when an electrical signal is received from the ECU in a normally open state. Also, the second simulator valve  3271  may be closed in the normal operation mode and the diagnosis mode of the electronic brake system  3000 . 
     The reservoir valve  3711  may be provided in the first reservoir flow path  1710  as a two-way control valve to control the flow of the braking fluid delivered through the first reservoir flow path  1710 . The reservoir valve  3711  may be provided as a normally closed type solenoid valve that operates to be open when an electrical signal is received from the ECU in a normally closed state. Accordingly, the reservoir valve  3711  may be closed in the normal operation mode, contrary to the reservoir valve  1711  of the electronic brake system  1000  according to the first embodiment of the disclosure. 
     Accordingly, when the electronic brake system  3000  according to the third embodiment of the disclosure operates in the abnormal operation mode (fallback mode), as the second simulation piston  1230  moves forward, the pressurized medium accommodated in the second simulation chamber  1230   a  is delivered to the first simulation chamber  1240   a  through the second simulation flow path  3270 , but the reservoir valve  3711  is maintained in the closed state, thereby may block the pressurized medium accommodated in the second simulation chamber  1230   a  from being delivered to the reservoir  1100 . Thus, the pressurized medium accommodated in the second simulation chamber  1230   a  may be provided to the first and second wheel cylinders  21  and  22  through the first backup flow path  1610 , and a braking stability may be improved and quick braking may be performed, which will be described in detail with reference to  FIG. 14 . 
     As described above, a description of the same operation as the electronic brake system  1000  according to the first embodiment of the disclosure is omitted to prevent duplication of content. Only pedal simulation operation of the integrated master cylinder  1200  in the normal operation mode of the electronic brake system  3000  according to the third embodiment of the disclosure is described. 
     With respect to the pedal simulation operation by the integrated master cylinder  1200 , in the normal operation mode (braking and release of braking), the driver operates the brake pedal  10 , and at the same time, the first cut valves  1611  and the second cut valves  1621 , and the reservoir valve  3711  and the second simulator valve  3271  operate to be closed, and thus the second simulation chamber  1230   a,  the first master chamber  1220   a  and the second master chamber  1220   b  may be sealed and the second simulation piston  1230  is not displaced. Accordingly, the elastic member  1250  is compressed by a displacement of the first simulation piston  1240 , an elastic restoring force by the compression of the elastic member  1250  may be provided the driver with a pedal feeling, and the pressurized medium accommodated in the first simulation chamber  1240   a  may be delivered to the reservoir  1100  through the first simulation flow path  1260 . Afterwards, when the driver releases the pressing force of the brake pedal  10 , the elastic member  1250  returns to its original position and shape by the elastic restoring force, and the first simulation chamber  1240   a  may be filled with the pressurized medium supplied from the reservoir  1100  through the first simulation flow path  1260 , or be filled with the pressurized medium supplied from the first hydraulic circuit  1510  through the first backup flow path  1610 . 
     Hereinafter, an operation in a fallback mode, i.e., in which the electronic brake system  3000  according to the third embodiment of the disclosure does not operate normally, is described. 
       FIG. 14  is a hydraulic circuit diagram illustrating an operation in an abnormal operation mode (fallback mode) where the electronic brake system  3000  according to the third embodiment of the disclosure may not operate normally due to a failure of device, and the like. 
     Referring to  FIG. 14 , in the abnormal operation mode, each of the valves is controlled to be in an initial braking state which is a non-operating state. In this instance, when the driver depresses the brake pedal  10 , the first simulation piston  1240  connected to the brake pedal  10  moves forward and thus displacement occurs. Because the first simulator valve  1261  is closed and the first cut valves  1611  are maintained in the open state, the pressurized medium accommodated in the first simulation chamber  1240   a  may be delivered to the first and second wheel cylinders  21  and  22  in the first hydraulic circuit  1510  through the first backup flow path  1610  by the forward movement of the first simulation piston  1240  to perform braking. 
     Also, when the first simulation piston  1240  moves forward, the second simulation chamber  1230   a  and the first master chamber  1220   a  are not sealed, and thus the elastic member  1250  is not compressed and the second simulation piston  1230  moves forward and displacement occurs. In this instance, because the reservoir valve  3711  is maintained in the closed state and the second simulator valve  3271  is maintained in an open state, the pressurized medium accommodated in the second simulation chamber  1230   a  may be delivered to the first simulation chamber  1240   a  through the second simulation flow path  3270  by the displacement of the second simulation piston  1230 , and also, as described above, may be delivered to the first and second wheel cylinders  21  and  22  of the first hydraulic circuit  1510  through the first backup flow path  1610  to perform braking. 
     At the same time, when a displacement occurs by moving the second simulation piston  1230  forward, because the first cut valves  1611  are maintained in the open state, the pressurized medium accommodated in the first master chamber  1220   a  may be delivered to the first and second wheel cylinders  21  and  22  in the first hydraulic circuit  1510  by sequentially passing through the auxiliary backup flow path  1630  and the first backup flow path  1610  to perform braking. On the other hand, as the second simulation piston  1230  moves forward, the cut-off hole  1231  provided in the second simulation piston  1230  blocks a connection between the first master chamber  1220   a  and the second reservoir flow path  1720 , and thereby may prevent the pressurized medium accommodated in the first master chamber  1220   a  from being delivered to the reservoir  1100 . 
     Also, when the second simulation piston  1230  moves forward, the pressurized medium in the first master chamber  1220   a  moves the master piston  1220  forward and displacement occurs. Because the second cut valves  1621  are maintained in the open state, the pressurized medium accommodated in the second master chamber  1220   b  may be delivered to the third and fourth wheel cylinders  23  and  24  of the second hydraulic circuit  1520  through the second backup flow path  1620  to perform braking. In this instance, as the master piston  1220  moves forward, the cut-off hole  1221  provided in the master piston  1220  blocks a connection between the second master chamber  1220   b  and the third reservoir flow path  1730 , and thereby may prevent the pressurized medium from being delivered to the reservoir  1100 . 
     In the abnormal operation mode, because the first cut valves  1611 , the second cut valves  1621  and the second simulator valve  3271  are in the open state and the reservoir valve  3711  and the first simulator valve  1261  are in the closed state, the hydraulic pressure transferred from the first simulation chamber  1240   a,  the second simulation chamber  1230   a,  the first master chamber  1220   a  and the second master chamber  1220   b  of the integrated master cylinder  1200 , i.e., all the chambers of the integrated master cylinder  1200 , may be directly transferred to each of the wheel cylinders  20 , thereby improving a braking stability and performing quick braking. 
     Hereinafter, a diagnosis mode of the electronic brake system  3000  according to the third embodiment of the disclosure is described. 
     The electronic brake system  3000  according to the third embodiment of the disclosure may perform the diagnosis mode for checking a leak of the integrated master cylinder  1200 .  FIG. 15  is a hydraulic circuit diagram illustrating that the electronic brake system  3000  according to the third embodiment of the disclosure operates in the diagnosis mode. Referring to  FIG. 15 , when the diagnosis mode is performed, the ECU may control the hydraulic pressure generated from the hydraulic pressure supply device  1300  to be supplied to the first simulation chamber  1240   a  of the integrated master cylinder  1200 . 
     As described above, a description of the same operation as the electronic brake system  1000  according to the first embodiment of the disclosure is omitted to prevent duplication of content. Only operation of a second simulation valve  3751  in the diagnosis mode of the electronic brake system  3000  according to the third embodiment of the disclosure is additionally described. 
     Specifically, in a state where each of the valves is controlled to be in the initial braking state which is a non-operating state, the ECU operates to move the hydraulic piston  1320  forward to generate a hydraulic pressure in the first pressure chamber  1330 , and at the same time, controls the second cut valves  1621  to be in the closed state. The hydraulic pressure generated in the first pressure chamber  1330  is 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 . Also, the pressurized medium delivered to the first hydraulic circuit  1510  is delivered to the first simulation chamber  1240   a  through the first backup flow path  1610  by opening at least a portion of the first cut valves  1611 . 
     In this instance, the first simulator valve  1261  remains closed and the second simulator valve  3271  is additionally controlled to be in a closed state, and thereby may prevent the first simulation chamber  1240   a  and the second simulation chamber  1230   a  from communicating with each other and seal the first simulation chamber  1240   a.    
     Meanwhile, for quick diagnosis, the first inlet valve  1511   a  and the second inlet valve  1511   b  provided in the first hydraulic circuit  1510  may be switched to the closed state. 
     In this state, by comparing a hydraulic pressure value of the pressurized medium expected to be generated by the displacement of the hydraulic piston  1320  with a hydraulic pressure value of the first simulation chamber  1240   a  or the first hydraulic circuit  1510  measured by the pressure sensor (PS), a leak of the integrated master cylinder  1200  or the first simulator valve  1261  may be diagnosed. Specifically, an estimated hydraulic pressure value calculated based on a displacement amount of the hydraulic piston  1320  or a rotational angle measured by the motor control sensor (not shown) is compared with an actual hydraulic pressure value of the first simulation chamber  1240   a  or the first hydraulic circuit  1510  measured by the pressure sensor (PS), and when the two hydraulic pressure values are the same, it may be determined that no leak occurs in the integrated master cylinder  1200  or the first simulator valve  1261 . By contrast, when the actual hydraulic pressure value of the first simulation chamber  1240   a  or the first hydraulic circuit  1510  measured by the pressure sensor is lower than the estimated 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), which indicates that a portion of the hydraulic pressure of the pressurized medium applied to the first simulation chamber  1240   a  is lost, and thus it may be determined that a leak occurs in the integrated master cylinder  1200  or the first simulator valve  1261  and this may be notified to the driver. Page  3