Patent Publication Number: US-2023134290-A1

Title: Hydraulic brake apparatus for vehicle and control method therefor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of priority to Korean Patent Application No. 10-2021-0147210, filed on Oct. 29, 2021, the disclosure of which is incorporated herein by this reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to a hydraulic brake apparatus for a vehicle and a method of controlling the same. 
     BACKGROUND 
     Description of this section only provides the background information of the present disclosure without configuring the related art. 
     A hydraulic brake apparatus for a vehicle is configured to brake a vehicle by transmitting hydraulic pressure, which is generated by a pump therein, to a plurality of wheel brakes mounted on different wheels. In order to prevent a wheel-lock phenomenon, a hydraulic brake apparatus for a vehicle has to be able to adjust the magnitude of hydraulic pressure that is transmitted to wheel brakes. Further, in order to perform an Electronic Stability Control (ESC) function, a hydraulic brake apparatus for a vehicle has to be able to independently transmit hydraulic pressure generated by a pump to a plurality of wheel brakes. That is, a hydraulic brake apparatus for a vehicle has to be able to adjust the path for transmitting hydraulic pressure. Such functions are for the safety of passengers in a vehicle and should be able to be necessarily performed by an automotive brake system. 
     A plurality of valves is mounted in the channels of a hydraulic brake apparatus to adjust the magnitude of hydraulic pressure that is transmitted to wheel brakes or to change the flow paths of fluid. A hydraulic brake apparatus adjusts the opening/closing states of a plurality of valves, that is, whether to open/close the valves, or the degrees of opening. When the functions described above are not appropriately performed due to contaminants stuck in even any one of a plurality of valves, etc., the safety of a vehicle is considerably deteriorated. For example, when braking pressure is supplied to only one wheel brake, the vehicle may be unexpectedly turned. 
     SUMMARY 
     The present disclosure relates to a hydraulic brake apparatus for a vehicle that can remove contaminants in a valve by controlling valves and a pump in the hydraulic brake apparatus even without an additional device, and a method of controlling the hydraulic brake apparatus. 
     However, the objects of the present disclosure are not limited to the objects described above and other objects will be clearly understood by those skilled in the art from the following description. 
     According to one aspect, the present disclosure provides a method for controlling a hydraulic brake apparatus for a vehicle that includes a brake device including a plurality of valves for selectively transmitting hydraulic pressure to a plurality of wheel brakes and a pressurizer for pressurizing fluid, and a control unit controlling the brake device. The method comprises: a target valve group closing process in which the control unit controls the brake device to close a target brake group selectively including the plurality of valves; a hydraulic pressure supply process in which the control unit controls the brake device to supply hydraulic pressure to at least one of channels separated by closing the target valve group; and a contaminant removal process in which the control unit controls the brake device such that the target valve group opens and the fluid washes the target valve group. 
     According to another aspect, the present disclosure provides a hydraulic brake apparatus for a vehicle that comprises a brake device including a plurality of valves for selectively transmitting hydraulic pressure to a plurality of wheel brakes and a pressurizer for pressurizing fluid using torque of a motor, and a control unit controlling the brake device. Herein, the control unit comprises: a receiving unit configured to receive a brake pedal stroke measured by a pedal stroke sensor, information sensed by a door sensor about whether a door is opened or close, and information for determining whether the engine of a vehicle is stopped; a pressurizer controller configured to control the brake device to supply hydraulic pressure to at least one of channels separated by closing a target valve group selectively including the plurality of valves, with the target valve group closed; and a valve controller configured to control the target valve group such that the target valve group closes to wash the target valve group, and control the target valve group such that the target valve group opens after hydraulic pressure is supplied to the at least one of the channels separated by closing the target valve group. 
     A hydraulic brake apparatus for a vehicle and a method of controlling the hydraulic brake apparatus according to an embodiment have an effect that it is possible to remove contaminants in a valve even without an additional device by controlling valves and a pump in the hydraulic brake apparatus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a hydraulic circuit diagram showing a hydraulic brake apparatus for a vehicle employing a control method according to an embodiment of the present disclosure. 
         FIG.  2    is a flowchart showing a control method according to an embodiment of the present disclosure. 
         FIG.  3    is a flowchart showing a process of removing contaminants according to an embodiment of the present disclosure. 
         FIG.  4    is a hydraulic circuit diagram showing the state in which a first target valve group according to an embodiment of the present disclosure is closed in a process of removing contaminants from the first target valve group. 
         FIG.  5    is a hydraulic circuit diagram showing the state in which the first target valve group according to an embodiment of the present disclosure is open in the process of removing contaminants from the first target valve group. 
         FIG.  6    is a hydraulic circuit diagram showing the state in which a second target valve group according to an embodiment of the present disclosure is closed in a process of removing contaminants from the second target valve group. 
         FIG.  7    is a hydraulic circuit diagram showing the state in which the second target valve group according to an embodiment of the present disclosure is open in the process of removing contaminants from the second target valve group. 
         FIG.  8    is a hydraulic circuit diagram showing the state in which a third target valve group according to an embodiment of the present disclosure is closed in a process of removing contaminants from the third target valve group. 
         FIG.  9    is a hydraulic circuit diagram showing the state in which the third target valve group according to an embodiment of the present disclosure is open in the process of removing contaminants from the third target valve group. 
         FIG.  10    is a hydraulic circuit diagram showing the state in which a fourth target valve group according to an embodiment of the present disclosure is closed in a process of removing contaminants from the fourth target valve group. 
         FIG.  11    is a hydraulic circuit diagram showing the state in which the fourth target valve group according to an embodiment of the present disclosure is open in the process of removing contaminants from the fourth target valve group. 
         FIG.  12    is a flowchart showing a process of determining whether a passenger gets off according to an embodiment of the present disclosure. 
         FIG.  13    is a flowchart showing a process of controlling a brake device of a self-test process according to an embodiment of the present disclosure. 
         FIG.  14    is a flowchart showing a process of determining whether there is leakage and/or a leakage position of the self-test process according to an embodiment of the present disclosure. 
         FIG.  15    is a block diagram showing the configuration of a hydraulic brake apparatus for a vehicle according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, some exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, like reference numerals preferably designate like elements, although the elements are shown in different drawings. Furthermore, in the following description of various exemplary embodiments of the present disclosure, a detailed description of known functions and configurations incorporated therein will be omitted for clarity and for brevity. 
     Additionally, various terms such as first, second, A, B, (i), (ii), (a), (b), etc., are used solely to differentiate one component from the other but not to imply or suggest the substances, order, or sequence of the components. Throughout the present specification, when a part ‘includes’ or ‘comprises’ a component, the part is meant to further include other components, not to exclude thereof unless specifically stated to the contrary. The terms such as ‘unit,’ ‘module,’ and the like refer to one or more units for processing at least one function or operation, which may be implemented by hardware, software, or a combination thereof. 
       FIG.  1    is a block diagram showing a hydraulic brake apparatus for a vehicle of a control method according to an embodiment of the present disclosure. 
     Referring to  FIG.  1   , a hydraulic brake apparatus of a control method according to an embodiment of the present disclosure includes some or all of a plurality of wheel brakes w 1 , w 2 , w 3 , and w 4 , a brake device  1100 , and a control unit  150  controlling the brake device  1100 . 
     The plurality of wheel brakes w 1 , w 2 , w 3 , and w 4  are configured to restrain rotation of wheels using hydraulic pressure generated by the brake device  1100 . The plurality of wheel brakes w 1 , w 2 , w 3 , and w 4  are mounted on different wheels and can apply a braking force to the corresponding wheels. The wheel brakes w 1 , w 2 , w 3 , and w 4  may be caliper type brakes or drum type brakes. In the present disclosure, the wheel brakes mounted on front wheels are referred to as front wheel brakes w 1  and w 2  and the wheel brakes mounted on rear wheels are referred to as rear wheel brakes w 3  and w 4 . 
     The brake device  1100  supplies hydraulic pressure, which is needed to brake a vehicle, to the wheel brakes w 1 , w 2 , w 3 , and w 4 . The brake device  1100  includes a pressurizer for pressurizing fluid, and a plurality of valves  1111  to  1117 , IV, IN, OV, and OUT for selectively transmitting fluid to the plurality of wheel brakes w 1 , w 2 , w 3 , and w 4 . 
     The pressurizer  120  includes some or all of a motor  1121 , a piston  1122 , and a hydraulic chamber  1123 ,  1124 . The pressurizer  120  may be driven by the motor  1121 . The pressurizer  1120  may include a power train (not shown) that converts torque of the motor  1121  into a force for translating the piston  1122 . The power train, which is a mechanism converting a rotation motion into a translation motion, for example, may use a ball screw and a screw nut. The piston  1122  may be configured to move forward or backward, depending on the rotation direction of the motor  1121 . In the present disclosure, the side opposite to the motor  1121  is referred to as a ‘front side,’ and the side of the motor  1121  is referred to as a ‘rear side’. The hydraulic chamber  1123 ,  1124 , which is a space in which fluid is pressurized, may be divided into two parts by the piston  1122 . The hydraulic chamber positioned ahead of the piston  1122  is referred to as first hydraulic chamber  1123 , and the hydraulic chamber positioned behind the piston  1122  is referred to as a second hydraulic chamber  1124 . When the piston  1122  moves forward, the fluid in the first hydraulic chamber  1123  is pressurized, and the fluid can be supplied into the second hydraulic chamber  1124 . When the piston  1122  moves backward, the fluid in the second hydraulic chamber  1124  is pressurized, and the fluid can be supplied into the first hydraulic chamber  1123 . However, the pressurizer of the present disclosure is not limited to such a double-acting pressurizer  1120 . The pressurizer  1120 , for example, may be a single-acting pressurizer  1120  configured such that fluid is not pressurized in the second hydraulic chamber  1124 , and fluid is supplied to the first hydraulic chamber  1123 . The pressurizer  1120  may include a cylinder of which the inner circumferential surface is in contact with the outer circumferential surface of the piston  1122 . The piston  1122  may slide and move toward the front or the rear of the cylinder, depending on the rotation direction of the motor  1121 . 
     The plurality of valves  1111  to  1117 , IV, IN, OV, and OUT may include a plurality of solenoid valve configured to the opening/closing states that are changed in accordance with an applied current value. For example, the plurality of valves  1111  to  1117 , IV, IN, OV, and OUT may include inlet valves IV and IN and outlet valves OV and OUT that are mounted on the wheel brakes w 1 , w 2 , w 3 , and w 4  to implement an ABS function. The inlet valves and the outlet valves that are mounted on the front wheel brakes w 1  and w 2  are referred to as front wheel inlet valves IN and front wheel outlet valves OUT, respectively, and the inlet valves and the outlet valves that are mounted on the rear wheel brakes w 3  and w 4  are referred to as rear wheel inlet valves IV and rear wheel outlet valves OV, respectively. 
     The front wheel inlet valves IN and the front wheel outlet valves OUT may be mounted in the channel connecting the front wheel brakes w 1  and w 2  and the first hydraulic chamber  1123 . The control unit  1500  can adjust hydraulic pressure that is transmitted to the front wheel brakes w 1  and w 2  from the first hydraulic chamber  1123  by controlling the opening/closing states of the front wheel inlet valves IN and the front wheel outlet valves OUT. Similarly, the rear wheel inlet valves IV and the rear wheel outlet valves OV may be mounted in the channel connecting the rear wheel brakes w 3  and w 4  and the second hydraulic chamber  1124 . The control unit  1500  can adjust hydraulic pressure that is transmitted to the rear wheel brakes w 3  and w 4  from the second hydraulic chamber  1124  by controlling the opening/closing states of the rear wheel inlet valves IV and the rear wheel outlet valves OV. A first block valve  1115  may be disposed in the channel connecting the first hydraulic chamber  1123  and the front wheel inlet valves IN and a second block valve  1116  may be disposed in the channel connecting the second hydraulic chamber  1124  and the rear wheel inlet valves IV. The first block valve  1115  may include a check valve that allows fluid to flow from the first chamber to the wheel brakes w 1 , w 2 , w 3 , and w 4  and prevents fluid from flowing from the wheel brakes w 1 , w 2 , w 3 , and w 4  to the first chamber. The second block valve  1116  may include a check valve that allows fluid to flow from the second chamber to the wheel brakes w 1 , w 2 , w 3 , and w 4  and prevents fluid from flowing from the wheel brakes w 1 , w 2 , w 3 , and w 4  to the second chamber. 
     The plurality of valves  1111  to  1117 , IV, IN, OV, and OUT may include a connection valve that fluid-communicates or disconnects at least some of the plurality of valves  1111  to  1117 , IV, IN, OV, and OUT and some other plurality of valves  1111  to  1117 , IV, IN, OV, and OUT to or from each other. The connection valve  1117  according to an embodiment of the present disclosure is configured to fluid-communicate or disconnect the channel connecting the first hydraulic chamber  1123  and the front wheel brakes w 1  and w 2  and the channel connecting the second hydraulic chamber  1124  and the rear wheel brakes w 3  and w 4  to or from each other. When the connection valve  1117  is opened, the channel connecting the first hydraulic chamber  1123  and the front wheel brakes w 1  and w 2  and the channel connecting the second hydraulic chamber  1124  and the rear wheel brakes w 3  and w 4  fluid-communicate with each other. 
     The plurality of valves  1111  to  1117 , IV, IN, OV, and OUT may include a third valve  1113  and a fourth valve  1114  that are mounted in the channel connecting the first chamber and an oil reservoir  1200 , and a first valve  1111  and a second valve  1112  that are mounted in the channel connecting the second chamber and the oil reservoir  1200 . 
     The control unit  1500  controls the brake device  1100 . The control unit  1500  can control rotation of the motor  1121  by adjusting the phase of the intensity of a current that is supplied to the motor  1121 . The control unit  1500  can control the opening/closing states of solenoid valves  1111  to  1117 , IV, IN, OV, and OUT by adjusting a current value that is applied to the solenoid valves  1111  to  1117 , IV, IN, OV, and OUT. 
       FIG.  2    is a flowchart showing a control method according to an embodiment of the present disclosure. 
     In the present disclosure, the fact that the control unit  1500  controls displacement of the piston  1122 , for example, may mean that the control unit  1500  moves the piston  1122  by adjusting a current that is applied to the motor  1121  of the pressurizer  1120 . Further, displacement of the piston  1122  may be measured by a rotation angle sensor (not shown) of the motor  1121  or a piston displacement sensor (not shown) in the pressurizer  1120 . 
     Referring to  FIGS.  1  and  2   , in the control method according to an embodiment of the present disclosure, the control unit  1500  controls the brake device  100  to remove contaminants at a target valve group including one or more values selected from the plurality of valves  1111  to  1117 , IV, IN, OV, and OUT (S 2200 ). The contaminants may be understood as substances that are included in the valves  1111  to  1117 , IV, IN, OV, and OUT, unlike the design specifications, and interfere with the intended driving of the brake device  1100 . In the process S 2200 , the control unit  1500  controls the opening/closing states of displacement of the piston  1122  and the valves  1111  to  1117 , IV, IN, OV, and OUT to remove contaminants as a target valve group. In this process, the brake device  1100  may generate braking pressure and driving noise while being driven. When the process S 2200  is performed with a passenger in a vehicle, the passenger may feel that the vehicle is driven differently from intention due to braking pressure and driving noise generated in the process S 2200 . Accordingly, whether a passenger has gotten off the vehicle may be determined before the process S 2200  (S 2100 ). When it is determined that a passenger has gotten off the vehicle in the step S 2100 , the process S 2200  is performed, and when it is determined that a passenger has not gotten off the vehicle, the control is ended. The control unit  1500  can determine whether there is leakage (i.e., a leakage occurrence) and/or a leakage position at the brake device  1100  with contaminants removed from the valves  1111  to  1117 , IV, IN, OV, and OUT using the process S 2200  (S 2300 ). 
       FIG.  3    is a flowchart showing a process of removing contaminants according to an embodiment of the present disclosure. 
     Referring to  FIGS.  1  and  3   , in the contaminant removal process S 2200 , the control unit  1500  controls the brake device  100  such that a target valve group selectively including the plurality of valves  1111  to  1117 , IV, IN, OV, and OUT is closed. Thereafter, as the target valve group is closed, the control unit  1500  controls the brake device  1100  to supply hydraulic pressure to at least one of separate channels. For example, the control unit  1500  may control the motor  1121  such that the piston  1122  moves forward or backward. Accordingly, by the valves  1111  to  1117 , IV, IN, OV, and OUT (hereafter, ‘target valves’) included in the target valve group, high hydraulic pressure is generated in the channel at a side of the target valves that is separate from the channel at another side of the target valves. Accordingly, a pressure difference is generated between the channel at a side and the channel at another side with the target valves therebetween. Thereafter, the control unit  1500  controls the brake device  1100  such that the target valve group is opened. When the target valve groups are opened, high-pressure fluid is transmitted from the channel at a side of the target valves to the channel at another side through the target valves. The contaminants in the target valves are removed while the high-pressure fluid passes through the target valves. According to the control method of an embodiment of the present disclosure, it is possible to remove contaminants in the brake device  1100  using the existing brake device  1100  and control unit  1500  without a new additional component. 
     The contaminant removal process may be performed on a plurality of target valve groups including a different combination of the valves  1111  to  1117 , IV, IN, OV, and OUT. In this case, the fact that the contaminant removal process is performed on any target valve group means that a process of removing contaminants at the target valve group by closing the target valve group, supplying hydraulic pressure to a channel, and opening the target valve group. For example, the contaminant removal process may be performed on a target valve group including some of the valves  1111  to  1117 , IV, IN, OV, and OUT mounted on the brake device  1100 , and then the contaminant removal process may be performed on a target valve group including the other valves  1111  to  1117 , IV, IN, OV, and OUT mounted on the brake device  1100 . Accordingly, it is possible to remove contaminants at all of the valves  1111  to  1117 , IV, IN, OV, and OUT mounted on the brake device  1100 . 
     The contaminant removal process according to an embodiment of the present disclosure is performed on each of first to fourth target valve groups  1111 ,  1112 ,  1116 ,  1117 , and OV. The first target valve group  1113 ,  1114 , OV, and OUT includes at least one of the valves  1111  to  1117 , IV, IN, OV, and OUT mounted in the channel connecting the first hydraulic chamber  1123  and the oil reservoir  1200 . The first target valve group  1113 ,  1114 , OV, and OUT may include the third valve  1113 , the fourth valve  1114 , the rear wheel outlet valve OV, and the front wheel outlet valve OUT. The second target valve group  1111 ,  1112 , OV, and OUT includes at least one of the valves  1111  to  1124 , IV, IN, OV, and OUT mounted in the channel connecting the second hydraulic chamber  1124  and the oil reservoir  1200 . The second target valve group  1111 ,  1112 , OV, and OUT may include the first valve  1111 , the second valve  1112 , the rear wheel outlet valve OV, and the front wheel outlet valve OUT. The third target valve group  1113 ,  1114 ,  1115 ,  1117 , and OUT includes at least one of the valves  1111  to  1117 , IV, IN, OV, and OUT mounted in the channel connecting the first hydraulic chamber  1123  and the wheel brakes w 1 , w 2 , w 3 , and w 4 . The third target valve group  1113 ,  1114 ,  1115 ,  1117 , and OUT may include the third valve  1113 , the fourth valve  1114 , the first block valve  1115 , the connection valve  1117 , and the front wheel outlet valve OUT. The fourth target valve group  1111 ,  1112 ,  1116 ,  1117 , and OV includes at least one of the valves  1111  to  1124 , IV, IN, OV, and OUT mounted in the channel connecting the second hydraulic chamber  1124  and the wheel brakes w 1 , w 2 , w 3 , and w 4 . The fourth target valve group  1111 ,  1112 ,  1116 ,  1117 , and OV may include the first valve  1111 , the second valve  1112 , the second block valve  1116 , the connection valve  1117 , and the rear wheel outlet valve OV. The contaminant removal process for the first target valve group  1113 ,  1114 , OV, and OUT, the contaminant removal process for the second target valve group  1111 ,  1112 , OV, and OUT, the contaminant removal process for the third target valve group  1113 , and the contaminant removal process for the fourth target valve group  1114  are sequentially performed, so all of the fifteen valves  1111  to  1117 , IV, IN, OV, and OUT shown in  FIG.  1    can be washed. 
     In the process of supplying hydraulic pressure, the channel to which the hydraulic pressure is supplied may be changed in accordance with the movement direction of the piston  1122 . For example, when the piston  1122  moves forward, hydraulic pressure may be supplied to the channel connected to the first chamber, and when the piston  1122  moves backward, hydraulic pressure may be supplied to the channel connected to the second chamber. Accordingly, the control method can configure a combination of valves  1111  to  1117 , IV, IN, OV, and OUT included in a target valve group in correspondence to the movement direction of the piston  1122 . The control unit  1500  can wash a plurality of target valve groups by controlling the movement direction of the piston  1122  and the opening/closing states of the valves  1111  to  1117 , IV, IN, OV, and OUT after controlling the pressurizer  1120  (S 2210 ) such that the displacement of the piston  1122  is initialized. The initialized position of the piston  1122  may be a position when the piston  1122  maximally moved toward the monitor  1121 . 
       FIG.  4    is a hydraulic circuit diagram showing the state in which a first target valve group according to an embodiment of the present disclosure is closed in a process of removing contaminants from the first target valve group. 
       FIG.  5    is a hydraulic circuit diagram showing the state in which the first target valve group according to an embodiment of the present disclosure is open in the process of removing contaminants from the first target valve group. 
     Referring to  FIGS.  2  to  4   , a contaminant removal process is performed on the first target valve group  1113 ,  1114 , OV, and OUT. The control unit  1500  controls the brake device  1100  such that the first target valve group  1113 ,  1114 , OV, and OUT is closed. Thereafter, the control unit  1500  controls the brake device  1100  such that the piston  1122  moves forward. The control unit  1500  can disconnect the outlet valves OV and OUT and the oil reservoir  1200  at a lower pressure by closing the second block valve  1116 . Accordingly, the hydraulic pressure of the channels indicated by bold lines in  FIG.  4    increases. That is, high hydraulic pressure is generated at a first side of each of the first target valves  1113 ,  1114 , OV, and OUT. 
     Referring to  FIGS.  2  to  5   , the control unit  1500  controls the brake device  1100  such that the first target valve group  1113 ,  1114 , OV, and OUT is opened with high hydraulic pressure generated at the first side of each of the first target valves  1113 ,  1114 , OV, and OUT. High-pressure fluid is transmitted to the channel at the first side of each of the first target valves  1113 ,  1114 , OV, and OUT to the channel at a second side through the first target valves  1113 ,  1114 , OV, and OUT. Accordingly, contaminants in the first target valve group  1113 ,  1114 , OV, and OUT are separated out from the first target valve group  1113 ,  1114 , OV, and OUT by the high-pressure fluid. Contaminants in each of the first target valves  1113 ,  1114 , OV, and OUT can be collected to the oil reservoir  1120  through the channel at the second side of each of the first target valves  1113 ,  1114 , OV, and OUT. 
     Such a contaminant removal process for the first target valve group  1113 ,  1114 , OV, and OUT may include the process S 2221  to S 2224  of  FIG.  2   . In the contaminant removal process for the first target valve group  1113 ,  1114 , OV, and OUT, the control unit  1500  controls the pressurizer  1120  such that the piston  1122  moves forward (S 2221 ). The control unit  1500  controls the brake device  1100  such that the first target valve group  1113 ,  1114 , OV, and OUT is closed (S 2222 ). As the first target valve group  1113 ,  1114 , OV, and OUT is closed after the process S 2222 , the control unit  1500  controls the brake device  1100  to supply hydraulic pressure to at least one of separate channels (S 2223 ). After the process S 2223 , the control unit  1500  controls the brake device  1100  such that the first target valve group  1113 ,  1114 , OV, and OUT is opened. Accordingly, the first target valve group  1113 ,  1114 , OV, and OUT is washed (S 2224 ). 
       FIG.  6    is a hydraulic circuit diagram showing the state in which a second target valve group according to an embodiment of the present disclosure is closed in a process of removing contaminants from the second target valve group. 
       FIG.  7    is a hydraulic circuit diagram showing the state in which the second target valve group according to an embodiment of the present disclosure is open in the process of removing contaminants from the second target valve group. 
     Referring to  FIGS.  2  to  6   , a contaminant removal process is performed on the second target valve group  1111 ,  1112 , OV, and OUT. The control unit  1500  controls the brake device  1100  such that the second target valve group  1111 ,  1112 , OV, and OUT is closed. Thereafter, the control unit  1500  controls the brake device  1100  such that the piston  1122  moves backward. The control unit  1500  can disconnect the outlet valves OV and OUT and the oil reservoir  1200  at lower pressure by closing the first block valve  1115 . Accordingly, the hydraulic pressure of the channels indicated by bold lines in  FIG.  6    increases. That is, high hydraulic pressure is generated at a first side of each of the second target valves  1111 ,  1112 , OV, and OUT. 
     Referring to  FIGS.  2  to  7   , the control unit  1500  controls the brake device  1100  such that the second target valve group  1111 ,  1112 , OV, and OUT is opened with high hydraulic pressure generated at the first side of each of the second target valves  1111 ,  1112 , OV, and OUT. High-pressure fluid is transmitted to the channel at the first side of each of the second target valves  1111 ,  1112 , OV, and OUT to the channel at a second side through the second target valves  1111 ,  1112 , OV, and OUT. Accordingly, contaminants in the second target valve group  1111 ,  1112 , OV, and OUT are separated out from the second target valve group  1111 ,  1112 , OV, and OUT by the high-pressure fluid. Contaminants in each of the second target valves  1111 ,  1112 , OV, and OUT can be collected to the oil reservoir  1112  through the channel at the second side of each of the second target valves  1111 ,  1112 , OV, and OUT. 
     Such a contaminant removal process for the second target valve group  1111 ,  1112 , OV, and OUT may include the process S 2231  to S 2234  of  FIG.  2   . In the contaminant removal process for the second target valve group  1111 ,  1112 , OV, and OUT, the control unit  1500  controls the pressurizer  1120  such that the piston  1122  moves backward (S 2231 ). The control unit  1500  controls the brake device  1100  such that the second target valve group  1111 ,  1112 , OV, and OUT is closed (S 2232 ). As the second target valve group  1111 ,  1112 , OV, and OUT is closed after the process S 2232 , the control unit  1500  controls the brake device  1100  to supply hydraulic pressure to at least one of separate channels (S 2233 ). After the process S 2233 , the control unit  1500  controls the brake device  1100  such that the second target valve group  1111 ,  1112 , OV, and OUT is opened. Accordingly, second target valve group  1111 ,  1112 , OV, and OUT is washed (S 2234 ). 
       FIG.  8    is a hydraulic circuit diagram showing the state in which a third target valve group according to an embodiment of the present disclosure is closed in a process of removing contaminants from the third target valve group. 
       FIG.  9    is a hydraulic circuit diagram showing the state in which the third target valve group according to an embodiment of the present disclosure is open in the process of removing contaminants from the third target valve group. 
     Referring to  FIGS.  2  to  8   , a contaminant removal process is performed on the third target valve group  1113 ,  1114 ,  1115 ,  1117 , and OUT. The control unit  1500  controls the brake device  1100  such that the third target valve group  1113 ,  1114 ,  1115 ,  1117 , and OUT is closed. Thereafter, the control unit  1500  controls the brake device  1100  such that the piston  1122  moves forward. Accordingly, the hydraulic pressure of the channels indicated by bold lines in  FIG.  8    increases. That is, high hydraulic pressure is generated at a first side of each of the third target valves  1113 ,  1114 ,  1115 ,  1117 , and OUT. 
     Referring to  FIGS.  2  to  9   , the control unit  1500  controls the brake device  1100  such that the third target valve group  1113 ,  1114 ,  1115 ,  1117 , and OUT is opened with high hydraulic pressure generated at one side of each of the third target valves  1113 ,  1114 ,  1115 ,  1117 , and OUT. High-pressure fluid is transmitted to the channel at the first side of each of the third target valves  1113 ,  1114 ,  1115 ,  1117 , and OUT to the channel at a second side through the third target valves  1113 ,  1114 ,  1115 ,  1117 , and OUT. Accordingly, contaminants in the third target valve group  1113 ,  1114 ,  1115 ,  1117 , and OUT are separated out from the third target valve group  1113 ,  1114 ,  1115 ,  1117 , and OUT by the high-pressure fluid. Contaminants in each of the third target valves  1113 ,  1114 ,  1115 ,  1117 , and OUT can be collected to the oil reservoir  1120  through the channel at the second side of each of the third target valves  1113 ,  1114 ,  1115 ,  1117 , and OUT. 
     Such a contaminant removal process for the third target valve group  1113 ,  1114 ,  1115 ,  1117 , and OUT may include the process S 2241  to S 2244  of  FIG.  2   . In the contaminant removal process for the third target valve group  1113 ,  1114 ,  1115 ,  1117 , and OUT, the control unit  1500  controls the pressurizer  1120  such that the piston  1122  moves forward (S 2241 ). The control unit  1500  controls the brake device  1100  such that the third target valve group  1113 ,  1114 ,  1115 ,  1117 , and OUT is closed (S 2242 ). As the third target valve group  1113 ,  1114 ,  1115 ,  1117 , and OUT is closed after the process S 2242 , the control unit  1500  controls the brake device  1100  to supply hydraulic pressure to at least one of separate channels (S 2243 ). After the process S 2243 , the control unit  1500  controls the brake device  1100  such that the third target valve group  1113 ,  1114 ,  1115 ,  1117 , and OUT is opened. Accordingly, the third target valve group  1113 ,  1114 ,  1115 ,  1117 , and OUT is washed (S 2244 ). 
       FIG.  10    is a hydraulic circuit diagram showing the state in which a fourth target valve group according to an embodiment of the present disclosure is closed in a process of removing contaminants from the fourth target valve group. 
       FIG.  11    is a hydraulic circuit diagram showing the state in which the fourth target valve group according to an embodiment of the present disclosure is open in the process of removing contaminants from the fourth target valve group. 
     Referring to  FIGS.  2  to  10   , a contaminant removal process is performed on the fourth target valve group  1111 ,  1112 ,  1116 ,  1117 , and OV. The control unit  1500  controls the brake device  1100  such that the fourth target valve group  1111 ,  1112 ,  1116 ,  1117 , and OV is closed. Thereafter, the control unit  1500  controls the brake device  1100  such that the piston  1122  moves backward. Accordingly, the hydraulic pressure of the channels indicated by bold lines in  FIG.  10    increases. That is, high hydraulic pressure is generated at a first side of each of the fourth target valves  1111 ,  1112 ,  1116 ,  1117 , and OV. 
     Referring to  FIGS.  2  to  11   , the control unit  1500  controls the brake device  1100  such that the fourth target valve group  1111 ,  1112 ,  1116 ,  1117 , and OV is opened with high hydraulic pressure generated at one side of each of the fourth target valves  1111 ,  1112 ,  1116 ,  1117 , and OV. High-pressure fluid is transmitted to the channel at the first side of each of the fourth target valves  1111 ,  1112 ,  1116 ,  1117 , and OV to the channel at a second side through the fourth target valves  1111 ,  1112 ,  1116 ,  1117 , and OV. Accordingly, contaminants in the fourth target valve group  1111 ,  1112 ,  1116 ,  1117 , and OV are separated out from the fourth target valve group  1111 ,  1112 ,  1116 ,  1117 , and OV by the high-pressure fluid. Contaminants in each of the third fourth target valves  1111 ,  1112 ,  1116 ,  1117 , and OV can be collected to the oil reservoir  1120  through the channel at the second side of each of the fourth target valves  1111 ,  1112 ,  1116 ,  1117 , and OV. 
     Such a contaminant removal process for the fourth target valve group  1111 ,  1112 ,  1116 ,  1117 , and OV may include the process S 2251  to S 2254  of  FIG.  2   . In the contaminant removal process for the third fourth target valve group  1111 ,  1112 ,  1116 ,  1117 , and OV, the control unit  1500  controls the pressurizer  1120  such that the piston  1122  moves backward (S 2251 ). The control unit  1500  controls the brake device  1100  such that the fourth target valve group  1111 ,  1112 ,  1116 ,  1117 , and OV is closed (S 2252 ). As the fourth target valve group  1111 ,  1112 ,  1116 ,  1117 , and OV is closed after the process S 2252 , the control unit  1500  controls the brake device  1100  to supply hydraulic pressure to at least one of separate channels (S 2253 ). After the process S 2253 , the control unit  1500  controls the brake device  1100  such that the fourth target valve group  1111 ,  1112 ,  1116 ,  1117 , and OV is opened. Accordingly, the fourth target valve group  1111 ,  1112 ,  1116 ,  1117 , and OV is washed (S 2254 ). 
     In  FIG.  2   , the contaminant removal process S 2221  to S 2224  for the first target valve group  1113 ,  1114 , OV, and OUT, the contaminant removal process S 2231  to S 2234  for the second target valve group  1111 ,  1112 , OV, and OUT, the contaminant removal process S 2241  to S 2244  for the third target valve group  1113 ,  1114 ,  1115 ,  1117 , and OUT, and the contaminant removal process S 2251  to S 2254  for the fourth target valve group  1111 ,  1112 ,  1116 ,  1117 , and OV are sequentially performed, but the contaminant removal process of the present disclosure is not limited to this sequence. For example, the contaminant removal process S 2221  to S 2234  for the first and second target valve groups  1111 ,  1112 , OV, and OUT may be performed after the contaminant removal process S 2241  to S 2254  for the third and fourth target valve groups  1111 ,  1112 ,  1116 ,  1117 , and OV. The process S 2221  to the process S 2254  may be sequentially performed while the piston  1122  reciprocates two times. 
       FIG.  12    is a flowchart showing a process of determining whether a passenger gets off according to an embodiment of the present disclosure. 
     Referring to  FIG.  12   , when a passenger gets off a vehicle, a brake pedal  1130  is not stroked. The passenger stops the engine of the vehicle before or immediately after getting off the vehicle. Further, the passenger opens and closes a door of the vehicle when getting off the vehicle. In order for the control unit  1500  to determine whether a passenger has gotten off the vehicle in the process S 2300 , the control unit  1500  determines whether the brake pedal  1300  is being stroked (S 2110 ). The control unit  1500  can determine whether the brake pedal  1300  is being stroked on the basis of a stroke signal generated by a pedal stroke sensor PS. The control unit  1500  determines whether the engine of the vehicle has been stopped (S 2120 ). The control unit  1500  determines whether a door of the vehicle has been opened and then stopped (S 2130 ). When determining that the brake pedal  1130  is not stroked, the engine of the vehicle is stopped, and a door of the vehicle has been opened and then closed, the control unit  1500  determines that a passenger has gotten off. Further, the control unit  1500  may further determine whether 1 minute has passed since the door was opened and then closed, and then determine that a passenger has gotten off when 1 minute has passed. If not, the control unit  1500  determines that a passenger is in the vehicle. 
       FIG.  13    is a flowchart showing a process of controlling a brake device of a self-test process according to an embodiment of the present disclosure. 
       FIG.  14    is a flowchart showing a process of determining whether there is leakage and/or a leakage position of the self-test process according to an embodiment of the present disclosure. 
     In the present disclosure, the fact that leakage occurred any channel means that fluid leaked on a path through which fluid can flow. When leakage occurs at a channel, for example, it includes leakage occurred at the valves  1111  to  1117 , IV, IN, OV, and OUT or the pressurizer  1120 . 
     Referring to  FIGS.  13  and  14   , in order for the control unit  1500  to determine whether there is leakage and/or a leakage position in the brake device  1100 , the control unit  1500  pressurizes the pressurizer  1120  such that the piston  1122  pressurizes the fluid in the first hydraulic chamber  1123  at first pressure (hereafter, a ‘first hydraulic chamber ( 1123  and  1124 )-pressurizing process’). The control unit  1500  controls the pressurizer  1120  such the piston  1122  pressurizes the fluid in the second hydraulic chamber  1124  at second pressure (hereafter, a ‘second hydraulic chamber ( 1123  and  1124 )-pressurizing process’). The control unit  1500  determines whether there is leakage and/or a leakage position in the brake device  1100  on the basis of displacement of the piston  1122  in the first hydraulic chamber ( 1123  and  1124 )-pressurizing process and/or the second hydraulic chamber ( 1123  and  1124 )-pressurizing process. 
     When the piston  1122  supplies hydraulic pressure to a channel and the channel is damaged, fluid leaks through the damaged portion and the piston  1122  moves further than expected displacement (hereafter, ‘expected displacement’) calculated on the basis of the initial design specifications and a desired braking force of the brake device  1100 . In this case, the desired braking force, which is a target braking force that is supposed to be applied to the vehicle by the hydraulic brake apparatus for a vehicle, may be calculated on the basis of a stroke signal generated by the pedal stroke sensor PS or a braking signal calculated by an autonomous driving system (not shown). When leakage occurs at the channel connected with the first hydraulic chamber  1123 , the piston  1122  moves toward the first hydraulic chamber  1123  further than the expected displacement when the piston pressurizes the first hydraulic chamber  1123 /Accordingly, when the piston  1122  moves further than first displacement in the first hydraulic chamber ( 1123  and  1124 )-pressurizing process, the control unit  1500  can determine that leakage is occurring at the channel connected to the first hydraulic chamber  1123 . 
     Similarly, when the piston  1124  moves further than second displacement in the second hydraulic chamber ( 1123  and  1124 )-pressurizing process, the control unit  1500  can determine that leakage is occurring at the channel connected to the second hydraulic chamber  1124 . In this case, the first displacement and the second displacement may be understood as expected displacement in the first hydraulic chamber ( 1123  and  1124 )-pressurizing process and expected displacement in the second hydraulic chamber ( 1123  and  1124 )-pressurizing process, respectively. Expected displacement according to a desired braking force may be stored in the form of a Look-Up Table (LUT) in a memory (not shown) of the control unit  1500 . 
     In a self-test process S 2300 , the control unit  1500  may control the connection valve  1117  such that the connection valve  1117  closes (S 2311 ), and may control the first hydraulic chamber ( 1123  and  1124 )-pressurizing process (S 2312 ) the second hydraulic chamber ( 1123  and  1124 )-pressurizing process (S 2313 ) with the connection valve  1117  closed. When the connection valve  1117  is closed, the channel connecting the first hydraulic chamber  1123  and the front wheel brakes w 1  and w 2  and the channel connecting the second hydraulic chamber  1124  and the rear wheel brakes w 3  and w 4  are fluid-disconnected from each other. In this state, when the piston  1122  pressurizes the first hydraulic chamber  1123 , hydraulic pressure is supplied to the channel connecting the first hydraulic chamber  1123  and the front wheel brakes w 1  and w 2  and the channel connecting the first hydraulic chamber  1123  and the oil reservoir  1200 . Accordingly, when the first hydraulic chamber  1123  is pressurized with the connection valve  1117  closed and the piston  1122  moves further than the first displacement, the control unit  1500  can determine that leakage occurred at the channel connecting the first hydraulic chamber  1123  and the front wheel brakes w 1  and w 2  and the channel connecting the first hydraulic chamber  1123  and the oil reservoir  1200 . Similarly, when the second hydraulic chamber  1124  is pressurized and the piston  1122  moves further than the second displacement, the control unit  1500  can determine that leakage occurred at the channel connecting the second hydraulic chamber  1124  and the rear wheel brakes w 3  and w 4  and the channel connecting the second hydraulic chamber  1124  and the oil reservoir  1200 . 
     It is unlikely that in a self-test process S 2300 , the control unit  1500  may control the connection valve  1117  such that the connection valve  1117  opens (S 2321 ), and may control the first hydraulic chamber ( 1123  and  1124 )-pressurizing process (S 2322 ) and the second hydraulic chamber ( 1123  and  1124 )-pressurizing process (S 2323 ) with the connection valve  1117  open. When the connection valve  1117  is opened, the channel connecting the first hydraulic chamber  1123  and the front wheel brakes w 1  and w 2  and the channel connecting the second hydraulic chamber  1124  and the rear wheel brakes w 3  and w 4  fluid-communicate with each other. In this state, when the piston  1122  pressurizes the first hydraulic chamber  1123 , hydraulic pressure is supplied to the hydraulic circuit connecting the first hydraulic chamber  1123  and the front wheel and rear wheel brakes w 1 , w 2 , w 3 , and w 4  and the hydraulic circuit connecting the first hydraulic chamber  1123  and the oil reservoir  1200 . Accordingly, when the first hydraulic chamber  1123  is pressurized with the connection valve  1117  open and the piston  1122  moves further than the first displacement, the control unit  1500  can determine that leakage occurred at the channel connecting the first hydraulic chamber  1123  and the front wheel and rear wheel brakes w 1 , w 2 , w 3 , and w 4  and the channel connecting the first hydraulic chamber  1123  and the oil reservoir  1200 . Similarly, when the second hydraulic chamber  1124  is pressurized and the piston  1122  moves further than the second displacement, the control unit  1500  can determine that leakage occurred at the channel connecting the second hydraulic chamber  1124  and the front wheel and rear wheel brakes w 1 , w 2 , w 3 , and w 4  and the channel connecting the second hydraulic chamber  1124  and the oil reservoir  1200 . 
     [Case 1] 
     Hereafter, a case in which it is possible to determine that leakage occurred at the channel connecting the first hydraulic chamber  1123  and the oil reservoir  1200  is described. Referring to  FIG.  14   , when the piston  1122  pressurizes the first hydraulic chamber  1123  with the connection valve  1117  closed, the piston  1122  moves further than the first displacement. When the piston  1122  pressurizes the first hydraulic chamber  1123  with the connection valve  1117  open, the piston  1122  moves further than the first displacement. When the piston  1122  pressurizes the second hydraulic chamber  1124  with the connection valve  1124  open, the piston  1122  moves by the second displacement. If the displacement of the piston  1122  in the series of processes of controlling the connection valve  1117  and the pressurizer  1120  is the same as those described above, the control unit  1500  can determine that leakage occurred at the channel connecting the first hydraulic chamber  1123  and the oil reservoir  1200  (S 2330 , S 2350 , and S 2351 ). 
     [Case 2] 
     Hereafter, a case in which it is possible to determine that leakage occurred at the channel connecting the first hydraulic chamber  1123  and the front wheel brakes w 1  and w 2  is described. When the piston  1122  pressurizes the first hydraulic chamber  1123  with the connection valve  1117  closed, the piston  1122  moves further than the first displacement. When the piston  1122  pressurizes the first hydraulic chamber  1123  with the connection valve  1117  open, the piston  1122  moves further than the first displacement. When the piston  1122  pressurizes the second hydraulic chamber  1124  with the connection valve  1124  open, the piston  1122  moves further than the second displacement. If the displacement of the piston  1122  in the series of processes of controlling the connection valve  1117  and the pressurizer  1120  is the same as those described above, the control unit  1500  can determine that leakage occurred at the channel connecting the first hydraulic chamber  1123  and the front wheel brakes w 1  and w 2  (S 2330 , S 2350 , and S 2352 ). 
     [Case 3] 
     Hereafter, a case in which it is possible to determine that leakage occurred at the channel connecting the second hydraulic chamber  1124  and the oil reservoir  1200  is described. When the piston  1122  pressurizes the second hydraulic chamber  1124  with the connection valve  1124  closed, the piston  1122  moves further than the second displacement. When the piston  1122  pressurizes the second hydraulic chamber  1124  with the connection valve  1124  open, the piston  1122  moves further than the second displacement. When the piston  1122  pressurizes the first hydraulic chamber  1123  with the connection valve  1123  open, the piston  1122  moves by the first displacement. If the displacement of the piston  1122  in the series of processes of controlling the connection valve  1117  and the pressurizer  1120  is the same as those described above, the control unit  1500  can determine that leakage occurred at the channel connecting the second hydraulic chamber  1124  and the oil reservoir  1200  (S 2330 , S 2340 , S 2360 , and S 2361 ). 
     [Case 4] 
     Hereafter, a case in which it is possible to determine that leakage occurred at the channel connecting the second hydraulic chamber  1124  and the rear wheel brakes w 3  and w 4  is described. When the piston  1122  pressurizes the second hydraulic chamber  1124  with the connection valve  1124  closed, the piston  1122  moves further than the second displacement. When the piston  1122  pressurizes the second hydraulic chamber  1124  with the connection valve  1124  open, the piston  1122  moves further than the second displacement. When the piston  1122  pressurizes the first hydraulic chamber  1123  with the connection valve  1117  open, the piston  1122  moves further than the first displacement. If the displacement of the piston  1122  in the series of processes of controlling the connection valve  1117  and the pressurizer  1120  is the same as those described above, the control unit  1500  can determine that leakage occurred at the channel connecting the second hydraulic chamber  1124  and the rear wheel brakes w 3  and w 4  (S 2330 , S 2340 , S 2360 , and S 2362 ). 
     [Case 5] 
     With the connection valve  1117  closed, when the piston  1122  pressurizes the first hydraulic chamber  1123  and does not move further than the first displacement and when the piston  1122  pressurizes the second hydraulic chamber  1124  and does not move further than the second displacement, the control unit  1500  determines that there is no leakage in the brake device  1100  (S 2330 , S 2340 , and S 2370 ). 
     The control unit  1500  can determine whether there is leakage by performing the first hydraulic chamber ( 1123  and  1124 )-pressurizing process and the second hydraulic chamber ( 1123  and  1124 )-pressurizing process with the connection valve  1117  closed. Thereafter, the control unit  1500  can determine a leakage position by performing the first hydraulic chamber ( 1123  and  1124 )-pressurizing process and the second hydraulic chamber ( 1123  and  1124 )-pressurizing process with the connection valve  1117  open. 
     If the displacement of the piston  1122  is the first displacement or more in the first hydraulic chamber ( 1123  and  1124 )-pressurizing process performed with the connection valve  1117  open and the displacement of the piston  1122  is less than the second displacement in the second hydraulic chamber ( 1123  and  1124 )-pressurizing process, the control unit  1500  determines that leakage occurred at the channel connecting the first hydraulic chamber  1123  and the oil reservoir  1200  (Case 1). 
     If the displacement of the piston  1122  is less than the first displacement in the first hydraulic chamber ( 1123  and  1124 )-pressurizing process performed with the connection valve  1117  open and the displacement of the piston  1122  is the second displacement or more in the second hydraulic chamber ( 1123  and  1124 )-pressurizing process, the control unit  1500  determines that leakage occurred at the channel connecting the second hydraulic chamber  1124  and the oil reservoir  1200  (Case 3). 
     Referring to  FIG.  13   , the control unit  1500  sequentially performs the first hydraulic chamber ( 1123  and  1124 )-pressurizing process (S 1123  and S 1124 ) and the second hydraulic chamber ( 1123  and  1124 )-pressurizing process (S 2311  to S 2313 ) with the connection valve  1117  closed, and then the first hydraulic chamber ( 1123  and  1124 )-pressurizing process (S 1123  and S 1124 ) and the second hydraulic chamber ( 1123  and  1124 )-pressurizing process (S 2311  to S 2313 ) with the connection valve  1117  open, but the control method of the present disclosure is not limited thereto. For example, the processes S 2311  to S 2313  may be performed after the processes S 2321  to S 2323 , or the second hydraulic chamber ( 1123  and  1124 )-pressurizing process may be performed before the first hydraulic chamber ( 1123  and  1124 )-pressurizing process. 
     Referring to  FIGS.  13  and  14   , the process of determining whether there is leakage and/or a leakage position (S 2323  to S 2351 ) of  FIG.  14    is performed after the process of controlling the connection valve  1117  and the pressurizer  1120  (S 2311  to S 2323 ) of  FIG.  13   , but the sequence is not limited to the sequence shown in the figures. For example, the processes S 2312 , S 2330 , S 2313 , and S 2340  may be sequentially performed. 
       FIG.  15    is a block diagram showing the configuration of a hydraulic brake apparatus for a vehicle according to an embodiment of the present disclosure. 
     The control method described above may be performed by a hydraulic brake apparatus for a vehicle according to an embodiment of the present disclosure. An embodiment of a hydraulic brake apparatus for a vehicle to be described hereafter may include the configuration of the hydraulic brake apparatus for a vehicle of the control method described above. The configuration and function of the hydraulic brake apparatus for a vehicle to be described hereafter correspond to the configuration and function of the hydraulic brake apparatus for a vehicle of the control method described above, so repeated description is omitted. 
     The control unit  1500  may include some or all of a receiving unit  1510 , a pressurizer controller  1520 , a valve controller  1530 , and a leakage determination unit  1540 . The receiving unit  1510  receives a brake pedal stroke, information about whether a door is opened/close, information for determining whether the engine of a vehicle is stopped, and information about displacement of the piston  1122 . The brake pedal stroke may be measured by the pedal stroke sensor PS and transmitted to the receiving unit  1510  in the form of an electrical signal. A door sensor  15   a  mounted on a door of a vehicle can transmit information about whether a door is opened/close to the receiving unit. An ignition device  15   b  can transmit whether the engine of a vehicle is started to the receiving unit  1510 . A piston displacement sensor  1122   a  can transmit information about displacement of the piston  1122  to the receiving unit  1510 . 
     The valve controller  1530  can adjust the opening/closing state of a target valve group by controlling a current value that is applied to a target valve that is a solenoid valve. The valve controller  1530  controls a target valve group such that the target valve group is closed in order to wash the target valve group. The pressurizer controller  1520  can change the magnitude of hydraulic pressure generated by the pressurizer  1120  or the channel through which hydraulic pressure is transmitted, by adjusting the intensity or the phase of a current that is applied to the motor  1121  that drives the pressurizer  1120 . The pressurizer controller  1120  control the pressurizer  1120  with a target valve group closed such that hydraulic pressure is supplied to at least one of channels separated by closing the target valve group. When hydraulic pressure is supplied to at least one of the channels separated by closing the target valve group by the pressurizer  1120 , the valve controller  1130  controls the target valve group such that the target valve group opens. 
     The leakage determination unit  1540  is configured to determine whether there is leakage and/or a leakage position in the brake device  1100 . The pressurizer controller  1520  can control the pressurizer  1120  such that the pressurizer  1120  pressurizes fluid at a preset magnitude. The leakage determination unit  1540  can determine whether there is leakage and/or a leakage position using the displacement of the piston  1122  in the pressurizer  1120  when fluid is pressurized by pressure having a preset magnitude. For example, the pressurizer controller  1120  can control the pressurizer such that the piston  1122  pressurizes the fluid in the first hydraulic chamber  1123  at first pressure or the piston pressurizes the fluid in the second hydraulic chamber  1124  at second pressure. The leakage determination unit  1540  can determine whether there is leakage and/or a leakage position in the brake device  1100  using the displacement of the piston when the first hydraulic chamber  1123  is pressurized at first pressure and the displacement of the piston  1122  when the second hydraulic chamber  1124  is pressurized at second pressure. 
     When the piston supplies hydraulic pressure to a channel and the channel is damaged, fluid leaks through the damaged portion, and the piston  1122  moves further than expected displacement. When leakage occurs at the channel connected with the first hydraulic chamber  1123 , the piston  1122  moves toward the first hydraulic chamber  1123  further than the expected displacement when the piston pressurizes the first hydraulic chamber  1123 /Accordingly, when the piston  1122  moves further than first displacement in the first hydraulic chamber ( 1123  and  1124 )-pressurizing process, the control unit  1500  can determine that leakage is occurring at the channel connected to the first hydraulic chamber  1123 . Similarly, when the piston  1124  moves further than second displacement in the second hydraulic chamber ( 1123  and  1124 )-pressurizing process, the control unit  1500  can determine that leakage is occurring at the channel connected to the second hydraulic chamber  1124 . In this case, the first displacement and the second displacement may be understood as expected displacement in the first hydraulic chamber ( 1123  and  1124 )-pressurizing process and expected displacement in the second hydraulic chamber ( 1123  and  1124 )-pressurizing process, respectively. Expected displacement according to a desired braking force may be stored in the form of a Look-Up Table (LUT) in a memory (not shown) of the control unit  1500 . 
     The foregoing descriptions of specific exemplary embodiments of the present disclosure have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described to explain certain principles of the present disclosure and their practical application, to enable others skilled in the art to make and utilize various exemplary embodiments of the present disclosure, as well as various alternatives and modifications thereof. It is intended that the scope of the present disclosure be defined by the Claims appended hereto and their equivalents.