Patent Publication Number: US-2023146790-A1

Title: Electric hydraulic brake

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on, and claims priority from, Korean Patent Application Number 10-2021-0151788, filed on Nov. 5, 2021, the disclosure of which is incorporated by reference herein in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to an electric hydraulic brake. 
     BACKGROUND 
     Description of this section only provides the background information of the present disclosure without configuring the related art. 
     An electric hydraulic brake generates hydraulic pressure using an electric motor and generates braking force at each of wheel cylinders by transmitting the hydraulic pressure to the wheel cylinders. An electric hydraulic brake makes it easy to individually control braking force that is generated at each wheel brake, and accordingly, it is possible to easily implement functions such as an Electronic Stability Control (ESC) System or an Anti-Lock Brake System (ABS). 
     ESC is for keeping the posture of a vehicle stable when the posture of the vehicle becomes unstable during driving. Factors that make the posture of a vehicle unstable are a slippery road condition due to rain, snow, sand, etc., motion inertia such as rapid zigzag driving, etc. An ESC system keeps the posture of a vehicle stable by controlling a brake and engine torque when the posture of the vehicle is dangerous. 
     Redundancy design of a brake system is required to prevent danger due to malfunction of a brake system that is electronically operated. For example, when the brake system of a vehicle electronically malfunctions, a driver can directly generate braking force in person by depressing a pedal using foot force. Alternatively, it is possible to configure a brake system in a 2-box type and generate braking force using another brake system when one brake system malfunctions. 
     However, when a brake system is configured in a 2-box type, there is a problem in that it is physically limited in terms of space to install two brake systems in an engine room. Further, there is another problem in that additional space and parts are needed to connect two controllers through a pipe. 
     Further, when inexpensive DC motor and two piston pumps are applied to dualize an actuator, there is a problem in that noise is generated due to pulsation for the characteristics of the piston pumps. 
     SUMMARY 
     According to at least one embodiment, the present disclosure provides an electric hydraulic brake including: a plurality of wheel brakes configured to supply braking force to wheels of a vehicle; a reservoir storing brake oil; a master cylinder connected to the reservoir and configured to generate hydraulic pressure in cooperation with a first motor; an auxiliary actuator including a second motor and a pump unit having three or more piston pumps linked with the second motor, and configured to transmit the hydraulic pressure to the plurality of wheel brakes when the master cylinder malfunctions; a hydraulic circuit configured to selectively transmit the hydraulic pressure to the plurality of wheel brakes, and including a front wheel hydraulic circuit configured to transmit the hydraulic pressure to a pair of front wheel brakes, a rear wheel hydraulic circuit configured to transmit the hydraulic pressure to a pair of rear wheel brakes, and a plurality of solenoid valves; a first controller configured to control the first motor and the hydraulic circuit in accordance with braking input; and a second controller configured to control the first motor and the front wheel hydraulic circuit when the first controller malfunctions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a hydraulic circuit diagram of an electric hydraulic brake according to an embodiment of the present disclosure. 
         FIG.  2    is a table showing a control relationship between first and second controllers and a plurality of solenoid valves of the electric hydraulic brake according to an embodiment of the present disclosure. 
         FIG.  3    is a hydraulic circuit diagram showing the flow of brake oil when there is malfunction in a master cylinder of the electric hydraulic brake according to an embodiment of the present disclosure. 
         FIGS.  4 A and  4 B  are graphs comparing operation noise of piston pumps of the electric hydraulic brake according to an embodiment of the present disclosure and an existing electric hydraulic brake. 
         FIGS.  5 A and  5 B  are graphs comparing the discharge amounts of piston pumps of the electric hydraulic brake according to an embodiment of the present disclosure and an existing electric hydraulic brake. 
         FIG.  6    is a view showing another embodiment of an electric hydraulic brake according to an embodiment of the present disclosure. 
         FIG.  7    is a view showing another embodiment of an electric hydraulic brake according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     An electric hydraulic brake according to an embodiment of the present disclosure can implement redundancy of a brake system of a vehicle by dually designing only a controller in one mechanical package. 
     An electric hydraulic brake according to an embodiment of the present disclosure can reduce pulsation and noise by applying and connecting an odd number of piston pumps for each circuit by improving the structure of an auxiliary actuator. 
     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. 
     Hereinafter, some 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. Further, in the following description of some embodiments, a detailed description of related known components and functions when considered to obscure the subject of the present disclosure will be omitted for the purpose of clarity and for brevity. 
     Additionally, alphanumeric codes such as first, second, i), ii), (a), (b), etc., in numbering components are used solely for the purpose of differentiating one component from the other but not to imply or suggest the substances, the order, or sequence of the components. Throughout this specification, when parts “include” or “comprise” a component, they are meant to further include other components, not excluding thereof unless there is a particular description contrary thereto. 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 hydraulic circuit diagram of an electric hydraulic brake according to an embodiment of the present disclosure. 
     Referring to  FIG.  1   , an electric hydraulic brake  100  according to an embodiment of the present disclosure may include all or some of a master cylinder  110 , a reservoir, a hydraulic circuit, and a controller. The controller may be an Electronic Control Unit (ECU). The controller may include a first controller  180  and a second controller  190 . 
     The master cylinder  110  may include all or some of a first motor  111 , a ball screw, a piston  113 , a first chamber  115 , and a second chamber  117 . 
     The master cylinder  110  can generate pressure of brake oil in cooperation with the first motor  111 . When a driver strokes a brake pedal, the first motor  111  is rotated by an electrical signal and the ball screw and the piston  113  linked with the first motor  111  are moved forward, so hydraulic pressure can be generated in the master cylinder. When the brake pedal is depressed, the master cylinder can supply the hydraulic pressure to a plurality of wheel brakes w 1 , w 2 , w 3 , and w 4 . In this case, a forward movement direction means that the piston  113  is moved toward the first chamber  115  and a backward movement direction means that the piston  113  is moved toward the second chamber  117 . 
     The master cylinder  110  may have a dual structure of which the inside is divided into the first chamber  115  and the second chamber by the piston  113 . The first motor  111  has a dual winding structure, and the first controller  180  and the second controller  190  each may control 50% of the first motor  111  under the assumption that the performance of the first motor  111  is 100. 
     The plurality of wheel brakes w 1 , w 2 , w 3 , and w 4  includes a first wheel brake w 1  that brakes the front left wheel of a vehicle, a second wheel brake w 2  that brakes the front right wheel of the vehicle, a third wheel brake w 3  that brakes the rear left wheel of the vehicle, and a fourth wheel brake w 4  that brakes the rear right wheel of the vehicle. The first to fourth wheel brakes w 1  to w 4  are formally defined for the convenience of description and the positions of the first to fourth wheel brakes w 1  to w 4  are not limited to the positions defined above. 
     The hydraulic circuit of the electric hydraulic brake  100  may include a front wheel hydraulic circuit and a rear wheel hydraulic circuit. The front wheel hydraulic circuit may be configured to transmit hydraulic pressure to a pair of front wheel brakes w 1  and w 2 . The rear wheel hydraulic circuit may be configured to transmit hydraulic pressure to a pair of rear wheel brakes w 3  and w 4 . 
     The front wheel hydraulic circuit may include all or some of a first main control valve  131 , a first main flow path  132 , inlet valves  141  and  142 , an inlet flow path, outlet valves  151  and  152 , and an outlet flow path. 
     The first main flow path  132  may be connected to the first chamber  115  of the master cylinder  110  via the first main control valve  131 . When the piston  113  is moved forward in accordance with a braking request, brake oil can be transmitted to the plurality of wheel brakes w 1  to w 4  from the first chamber  115  through the first main flow path  132 . The first main control valve  131  can adjust the hydraulic pressure that is transmitted from the first chamber  115  to the plurality of wheel brakes w 1  to w 4 . The first main control valve  131  may be a normal open type solenoid valve that is normally open and operates to close when receiving a closing signal from the controller (ECU). 
     The front wheel hydraulic circuit may include one or more inlet flow paths diverging from the first main flow path  132  to transmit hydraulic pressure to the front wheel brakes w 1  and w 2 , respectively. The inlet valves  141  and  142  are installed in the inlet flow path and can control the hydraulic pressure, which is transmitted to the front wheel brakes w 1  and w 2 , respectively, when braking is required. 
     The front wheel hydraulic circuit may include one or more outlet flow paths connecting the front wheel brakes w 1  and w 2  to the reservoir, respectively. The outlet valves  151  and  152  are installed in the outlet flow path and can control the hydraulic pressure, which is discharged from the front wheel brakes w 1  and w 2 , respectively, when braking is stopped. 
     The rear wheel hydraulic circuit may include all or some of a second main control valve  133 , a second main flow path  134 , inlet valves  143  and  144 , an inlet flow path, outlet valves  153  and  154 , and an outlet flow path. 
     The second main flow path  134  may be connected to the second chamber  117  of the master cylinder  110  via the second main control valve  133 . When the piston  113  is moved backward in accordance with a braking request, brake oil can be transmitted to the plurality of wheel brakes w 1  to s 4  from the second chamber  117  through the second main flow path  134 . The second main control valve  133  can adjust the hydraulic pressure that is transmitted from the second chamber  117  to the plurality of wheel brakes w 1  to w 4 . The second main control valve  133  may be a normal open type solenoid valve that is normally open and operates to close when receiving a closing signal from a controller. 
     The rear wheel hydraulic circuit may include one or more inlet flow paths diverging from the second main flow path  134  to transmit hydraulic pressure to the rear wheel brakes w 3  and w 4 , respectively. The inlet valves  143  and  144  are installed in the inlet flow path and can control the hydraulic pressure, which is transmitted to the front wheel brakes w 3  and w 4 , respectively, when braking is required. 
     The rear wheel hydraulic circuit may include one or more outlet flow paths connecting the front wheel brakes w 3  and w 4  to the reservoir, respectively. The outlet valves  153  and  154  are installed in the outlet flow path and can control the hydraulic pressure, which is discharged from the front wheel brakes w 3  and w 4 , respectively, when braking is stopped. 
     The inlet valves  141  to  144  are disposed at the upstream side of the wheel brakes w 1  to w 4  and may be normal open type solenoid valves that are normally open and operate to close when receiving a closing signal from a controller. The outlet valves  151  to  154  are disposed at the downstream side of the inlet valves  141  to  144  and may be normal closed type solenoid valves that are normally closed and operate to open when receiving an opening signal from a controller. 
     The electric hydraulic brake  100  according to an embodiment of the present disclosure may further include an auxiliary actuator  120 . The auxiliary actuator  120  may include a second motor  121  and a pump unit. The second motor may be a Direct Current (DC) motor. 
     When the master cylinder  110  cannot transmit hydraulic pressure to the plurality of wheel brakes w 1 , w 2 , w 3 , and w 4  due to malfunction of the first motor  111  or the ball screw of the master cylinder  110 , the auxiliary actuator  120  may be used. The second motor  121  is controlled by the first controller  180  and the second controller  190  and can generate pressure of brake oil using a pump unit. Since the electric hydraulic brake  100  includes the auxiliary actuator  120 , the actuator is dualized, so reliability of the brake system can be improved. 
     The pump unit may include a front wheel pump unit  123  connected to the front wheel hydraulic circuit and a rear wheel pump unit  125  connected to the rear wheel hydraulic circuit. The front wheel pump unit  123  can transmit hydraulic pressure to the plurality of wheel brakes w 1 , w 2 , w 3 , and w 4  through a first auxiliary flow path  122  connected to the front wheel inlet flow path. The rear wheel pump unit  125  can transmit hydraulic pressure to the plurality of wheel brakes w 1 , w 2 , w 3 , and w 4  through a second auxiliary flow path  124  connected to the rear wheel inlet flow path. 
     The pump unit may include an odd number of piston pumps. It is possible to reduce pulsation and noise that are generated in the existing ESCs by connecting an odd number of piston pumps to the second motor  121 . 
     Further, more piston pumps of the odd number of piston pumps may be disposed at the front wheel pump unit  123  than the rear wheel pump unit  125 . For example, when the pump unit includes three piston pumps, two piston pumps may be disposed at the front wheel pump unit  123  and one piston pump may be disposed at the rear wheel pump unit  125 . Since more piston pumps are disposed at the front wheel pump unit  123  than the rear wheel pump unit  125 , it is possible to generate braking force at a higher pressure-increasing speed using the auxiliary actuator  120  when the master cylinder  110  and the rear wheel hydraulic circuit malfunction. 
     The electric hydraulic brake  100  according to an embodiment of the present disclosure may further include a fixing valve  161 , a mixing flow path, and a recovery valve  171 . 
     The mixing valve  161  may be installed in a mixing flow path connecting the front wheel hydraulic circuit and the rear wheel hydraulic circuit. The mixing valve  161  can control hydraulic pressure that is transmitted between the front wheel hydraulic circuit and the rear wheel hydraulic circuit. The mixing valve  161  may be a Low pressure Switching Valve (LSV). The mixing valve  161  may be a normal closed type solenoid valve that is normally closed and operates to open when receiving an opening signal. 
     The electric hydraulic brake  100  according to an embodiment of the present disclosure may implement redundancy by dually configuring the first controller  180  and the second controller  190 . That is, by dually installing only controller in one mechanical package, even if one controller malfunctions, the other controller can secure braking force of the electric hydraulic brake  100 . 
     The first controller  180  and the second controller  190  each may include a 46-pin connector and a Micro Controller Unit (MCU). A plurality of solenoid valves of the front wheel hydraulic circuit may be connected to the first controller  180  and the second controller  190 . That is, even if the first controller  180  malfunctions, the front wheel hydraulic circuit can perform control using the second controller  190 . A plurality of solenoid valves of the rear wheel hydraulic circuit may be connected to the first controller  180 . 
     In a normal state, the first controller  180  and the second controller  190  can control the electric hydraulic brake  100  by cooperating with each other. When the first controller  180  malfunctions, the second controller  190  can control a Conventional Brake System (CBS). When the second controller  190  malfunctions, the first controller  180  can control an Electronic Parking Brake (EPB). 
     When the electric hydraulic brake  100  does not malfunction, the first controller  180  and the second controller  190  can control the first motor  111  and the first controller  180  controls the second main control valve  133  and the mixing valve  161 , so it is possible to generate braking force. 
     When a braking request is generated, the first controller  180  and the second controller  190  rotate the first motor  111 , and the ball screw and the piston  113  that are linked with the first motor  111  are moved forward, so hydraulic pressure is generated in the master cylinder  110 . When the piston  113  is moved forward, the hydraulic pressure generated in the master cylinder  110  can be transmitted to the plurality of wheel brakes w 1 , w 2 , w 3 , and w 4  via the first main control valve  131 , the plurality of inlet valves  141  to  144 , and the mixing valve  161 . 
     When a braking request is generated, the first controller  180  can control the second main control valve  133  and the mixing valve  161 . The first controller  180  can close the second main control valve  133  by transmitting a closing signal to the second main control valve  133 . The first controller  180  can open the mixing valve  161  by transmitting an opening signal to the mixing valve  161 . 
     When the electric hydraulic brake  100  does not malfunction, the first controller  180  can control the second main controller  133  with the brake pedal released. The first controller  180  can remove residual pressure by opening and then closing again the second main control valve  133 . Hydraulic pressure can be transmitted to the reservoir through the outlet flow path with the brake pedal released. 
     When the rear wheel hydraulic circuit malfunctions, the first controller  180  can close the mixing valve  161  by transmitting a closing signal to the mixing valve  161 . The electric hydraulic brake  100  can generate braking force using only by the front wheel hydraulic circuit by closing the mixing valve  161 . Further, the first controller  180  and the second controller  190  can remove residual pressure by controlling the front wheel outlet valves  151  and  152  with the brake pedal released. The electric hydraulic brake  100  can generate braking force using only the front wheel hydraulic circuit and the EPB. Accordingly, the electric hydraulic brake  100  can show performance of about 65% in comparison the normal state. The functions such as an Electronic Stability Control System (ESC) and an Anti-Lock Brake System (ABS) of the electric hydraulic brake  100  can be converted into a degraded mode in comparison to the normal state. Further, it is possible to perform steering and cooperative control to secure stability of a vehicle. 
     When the front wheel hydraulic circuit malfunctions, the first controller  180  can close the first main control valve  131  by transmitting a closing signal to the first main control valve  131 . The first controller  180  can open the second main control valve  133  by transmitting an opening signal to the second main control valve  133 . The electric hydraulic brake  100  can generate braking force using only the rear wheel hydraulic circuit by closing the first main control valve  131  and the second main control valve  133 . Further, the first controller  180  can remove residual pressure by controlling the recovery valve  171  with the brake pedal released. The electric hydraulic brake  100  can generate braking force using only the rear wheel hydraulic circuit and the EPB. Accordingly, the electric hydraulic brake  100  can show performance of about 40% in comparison the normal state. The functions such as an ESC and an ABS can also be converted into a degraded mode in comparison to the normal state. Further, it is possible to perform steering and cooperative control to secure stability of a vehicle. 
     Even if the second controller  190  malfunctions, it is possible to transmit hydraulic pressure to the plurality of wheel brakes w 1 , w 2 , w 3 , and w 4  in the same way as the normal state. When a braking request is generated, the first controller  180  rotates the first motor  111 , and the ball screw and the piston  113  that are linked with the first motor  111  are moved forward, so hydraulic pressure is generated in the master cylinder  110 . When the piston  113  is moved forward, the hydraulic pressure generated in the master cylinder  110  can be transmitted to the plurality of wheel brakes w 1 , w 2 , w 3 , and w 4  via the first main control valve  131 , the plurality of inlet valves  141  to  144 , and the mixing valve  161 . When a braking request is generated, the first controller  180  can control the second main control valve  133  and the mixing valve  161 . The first controller  180  can close the second main control valve  133  by transmitting a closing signal to the second main control valve  133 . The first controller  180  can open the mixing valve  161  by transmitting an opening signal to the mixing valve  161 . The situation in which the brake pedal is released in the same as the case of  FIG.  3   . That is, even if the second controller  190  malfunctions, it is possible to control a plurality of solenoid valves using the first controller  190  in the same was as the normal state. 
     When the second controller  190  malfunctions, the rear wheel left EPB that is controlled by the second controller  190  cannot be used. Further, since the first controller  180  and the second controller  190  control the motor  111  in the ratio of 1:1, the output of the first motor  111  may be limited to 50% of the normal state. 
     When the first controller  180  malfunctions, the electric hydraulic brake  100  can generate braking force using only the front wheel hydraulic circuit. The electric hydraulic brake  100  can generate braking force using only the front wheel hydraulic circuit and the rear wheel left EPB. Accordingly, the electric hydraulic brake  100  can show performance of about 65% in comparison the normal state. The functions such as an ESC and an ABS can also be converted into a degraded mode in comparison to the normal state. Further, it is possible to perform steering and cooperative control to secure stability of a vehicle. 
       FIG.  2    is a table showing a control relationship between first and second controllers and a plurality of solenoid valves of the electric hydraulic brake according to an embodiment of the present disclosure. 
     Referring to  FIG.  2   , the first controller  180  can control the front wheel hydraulic circuit and the rear wheel hydraulic circuit. The first controller  180  can control the first main controller  131 , the second main controller  133 , the inlet valves  141  to  144 , the outlet valve  151  to  154 , the mixing valve  161 , the recovery valve  171 , the first motor  111 , the pressure sensor  162 , and the rear wheel right EPB. 
     The second controller  190  can control the front wheel hydraulic circuit. The second controller  190  can control the first main controller  131 , the front wheel inlet valves  141  and  142 , the front wheel outlet valve  151  and  152 , the first motor  111 , the pressure sensor  162 , and the rear wheel left EPB. The first controller  180  and the second controller  190  can control the hydraulic circuits by cooperating with each other through communication in real time. 
     The electric hydraulic brake  100  may include two or more pressure sensor  162  and the pressure sensor  162  can communicate with the first controller  180  and the second controller  190 . The pressure sensor  162  may be positioned in the front wheel hydraulic circuit. However, the pressure sensor  162  is not limited to the position described above as an embodiment. The auxiliary actuator  120  can be controlled by the first controller  180  and the second controller  190 . 
     The first main controller  131 , the front wheel inlet valves  141  and  142 , and the front wheel outlet valve  151  and  152  that are connected to the second controller  190  can be controlled using the second controller  190  even if the first controller  180  malfunctions. 
       FIG.  3    is a hydraulic circuit diagram showing the flow of brake oil when there is malfunction in a master cylinder of the electric hydraulic brake according to an embodiment of the present disclosure. 
     Referring to  FIG.  3   , when the first motor  111  and the ball screw of the master cylinder  110  malfunction, the electric hydraulic brake  100  can use the auxiliary actuator  120 . The auxiliary actuator  120  can generate pressure of brake oil using the pump unit by operating the second motor  121 . 
     The pump unit may include an odd number of piston pumps. It is possible to reduce pulsation and noise that are generated in the existing ESCs by connecting an odd number of piston pumps to the second motor  121 . In this case, the piston pumps all have the same specifications, two piston pumps may be disposed at the front wheel pump unit  123  connected to the front wheel hydraulic circuit having a large amount of necessary liquid, and one piston pump may be disposed at the rear wheel pump unit  125  connected to the rear wheel hydraulic circuit. 
     When a braking request is generated, the first controller  180  can control the first main control valve  131 , the second main control valve  133 , and the mixing valve  161 . The first controller  180  can close the second main control valve  133  by transmitting a closing signal to the first main control valve  131  and the second main control valve  133 . The first controller  180  can open the mixing valve  161  by transmitting an opening signal to the mixing valve  161 . That is, by opening the mixing valve  161 , it is possible to increase the pressure of brake oil using three pistons. 
       FIGS.  4 A and  4 B  are graphs comparing operation noise of piston pumps of the electric hydraulic brake according to an embodiment of the present disclosure and an existing electric hydraulic brake.  FIGS.  5 A and  5 B  are graphs comparing the discharge amounts of piston pumps of the electric hydraulic brake according to an embodiment of the present disclosure and an existing electric hydraulic brake. 
     Referring to  FIGS.  4 A,  4 B,  5 A, and  5 B , it is possible to improve the Noise Vibration Harshness (NVH) function of the electric hydraulic brake  100  by applying three piston pumps. 
       FIG.  4 A  is a graph showing the NVH of an existing electric hydraulic brake not including a damper. Referring to  FIG.  4 A , it can be seen that the NVH of the existing electric hydraulic brake not including a damper is high. 
       FIG.  4 B  is a graph showing the NVD of an electric hydraulic brake  100  including three piston pumps according to an embodiment of the present disclosure. Referring to  FIG.  4 B , it can be seen that the NVH of the electric hydraulic brake  100  decreased in comparison to the existing electric hydraulic brake. It is possible to reduce noise by offsetting pulsations that are generated by piston pumps using an odd number of piston pumps. 
     Referring to  FIGS.  5 A and  5 B , it is possible to compare the discharge amounts of brake oil of piston pumps of the electric hydraulic brake  100  according to an embodiment and an existing electric hydraulic brake. The individual discharge amounts ESC MC1 and MC2 of the piston pumps of the existing electric hydraulic brake are larger than the individual discharge amount Premium MC1 and MC2 of the piston pumps of the electric hydraulic brake  100  according to an embodiment, but brake oil can be discharged only for a half of one rotation the first motor  121 . Accordingly, the average discharge amount ESC Average of the existing electric hydraulic brake is smaller than the average discharge amount Premium Average of the electric hydraulic brake  100  according to an embodiment. 
     Accordingly, the existing electric hydraulic brake discontinuously discharges brake oil, but the electric hydraulic brake  100  according to an embodiment continuously discharges brake oil, so pulsation is less and the NVH performance is excellent. 
       FIG.  6    is a view showing another embodiment of an electric hydraulic brake according to an embodiment of the present disclosure.  FIG.  7    is a view showing another embodiment of an electric hydraulic brake according to an embodiment of the present disclosure. 
     Referring to  FIG.  6   , the intake flow path structure of the pump unit of the auxiliary actuator  120  in the electric hydraulic brake  100  may be changed. The auxiliary actuator  120  may directly connect the intake flow path of a pump unit directly to the reservoir rather than the master cylinder  110 . 
     By directly connecting the intake flow path of the pump unit of the auxiliary actuator  120  with the reservoir, it is possible to increase the discharge amount of brake oil with the master cylinder  110  when a large discharge amount of brake oil is required. 
     Referring to  FIG.  7   , the number of the piston pumps of the pump unit of the assistant actuator  120  in the electric hydraulic brake  100  may be changed. It is possible to dispose three piston pumps at the front wheel pump unit  123  and three piston pumps at the rear wheel pump unit  125 . That is, it is possible to dispose three piston pumps at each of the front wheel hydraulic circuit and the rear wheel hydraulic circuit. 
     By disposing three piston pumps at each hydraulic circuit, it is possible to improve the pressure-increasing performance and the NVH performance of the electric hydraulic brake  100 . Further, there is also an effect that it is possible to reduce the size of each piston pump. 
     According to an embodiment, the electric hydraulic brake has only a controller dually designed in one mechanical package, so there is an effect that it is possible to implement redundancy of a brake system of a vehicle and to reduce an installation space and the manufacturing cost by decreasing parts. 
     According to an embodiment, the electric hydraulic brake reduces noise by offsetting pulsations that are generated by piston pumps, so there is an effect that a sense of incongruity is not transmitted to a driver. 
     Although exemplary embodiments of the present disclosure have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions, and substitutions are possible, without departing from the idea and scope of the claimed invention. Therefore, exemplary embodiments of the present disclosure have been described for the sake of brevity and clarity. The scope of the technical idea of the present embodiments is not limited by the illustrations. Accordingly, one of ordinary skill would understand that the scope of the claimed invention is not to be limited by the above explicitly described embodiments but by the claims and equivalents thereof.