JP5949093B2 - Braking control device for vehicle - Google Patents

Description

  The present invention relates to a vehicle brake control device that controls a braking force applied to a vehicle in accordance with a brake operation amount by a driver.

  As an example of a vehicle braking control device, a vehicle braking device described in Patent Document 1 is known. This vehicle braking device sets a drive start pressure and a drive stop pressure of a pump that accumulates brake fluid in an accumulator based on a vehicle speed or the like. Specifically, when a high braking force is required, the pump driving start pressure and the pump driving stop pressure are set to be high so as to secure the hydraulic pressure necessary for braking. On the other hand, when a high braking force is not required, the pump drive start pressure and the pump drive stop pressure are set low. Thereby, the frequency which an accumulator pressure becomes high is reduced and it aims at the improvement of durability of a pump and an accumulator.

JP-A-2005-35356

  However, in the vehicle braking device described in Patent Document 1, the accumulator pressure does not decrease unless the brake fluid accumulated in the accumulator is consumed, so that the durability of the pump and the accumulator cannot be improved sufficiently.

  This invention is made in view of such a situation, and makes it a subject to provide the brake control apparatus for vehicles with high durability which can ensure the accumulator pressure required for braking.

The vehicular braking control apparatus according to claim 1 is a vehicular braking control apparatus that includes a pressure accumulating unit that accumulates brake fluid, and pressurizes a wheel cylinder of the vehicle using the fluid pressure of the accumulating unit, When the brake fluid discharge unit capable of discharging the brake fluid accumulated in the pressure storage unit, a vehicle speed acquisition unit that acquires the vehicle speed of the vehicle, and the vehicle speed acquired by the vehicle speed acquisition unit are less than a predetermined speed A brake fluid discharge controller that discharges the brake fluid accumulated in the pressure accumulator by the brake fluid discharger, a pump that communicates with the pressure accumulator and can discharge the brake fluid to the pressure accumulator, A hydraulic pressure acquisition unit that acquires the hydraulic pressure of the brake fluid stored in the pressure storage unit, and the pump that receives the hydraulic pressure acquired by the hydraulic pressure acquisition unit is less than a predetermined pump operation start hydraulic pressure. A pump control unit that starts discharge of the brake fluid and stops discharge of the brake fluid by the pump when the hydraulic pressure acquired by the hydraulic pressure acquisition unit is equal to or higher than a predetermined pump operation stop hydraulic pressure; A pump operating fluid pressure setting unit that sets the pump actuation start hydraulic pressure and the pump actuation stop hydraulic pressure lower when the vehicle speed is less than the predetermined speed compared to when the vehicle speed is greater than or equal to the predetermined speed; I have.

The vehicle brake control device according to claim 2 is the vehicle brake control device according to claim 1, wherein the brake fluid discharge control unit is configured such that the hydraulic pressure acquired by the hydraulic pressure acquisition unit is The brake fluid accumulated in the pressure accumulating portion is discharged by the brake fluid discharging portion until the hydraulic pressure is lower than the pump operation stop hydraulic pressure.

The brake control apparatus for a vehicle according to claim 3, in the braking control apparatus for a vehicle according to claim 2, wherein the brake fluid discharge control section, the fluid pressure obtained by the hydraulic acquiring unit said The brake fluid accumulated in the pressure accumulating portion is discharged by the brake fluid discharge portion until the hydraulic pressure becomes equal to or higher than the pump operation start hydraulic pressure .

The braking control device for a vehicle according to claim 4 is a braking control device for a vehicle that includes a pressure accumulating unit that accumulates brake fluid and pressurizes a wheel cylinder of the vehicle using the fluid pressure of the accumulating unit, When the brake fluid discharge unit capable of discharging the brake fluid accumulated in the pressure storage unit, a vehicle speed acquisition unit that acquires the vehicle speed of the vehicle, and the vehicle speed acquired by the vehicle speed acquisition unit are less than a predetermined speed Further, the brake fluid discharge control unit that discharges the brake fluid accumulated in the pressure accumulating unit by the brake fluid discharge unit, and the output piston is driven by the servo pressure in the servo chamber to move, and the movement of the output piston Is connected to the master cylinder configured to change the master pressure in the master chamber, the pressure accumulating unit, the master chamber, and the servo chamber, and accumulates pressure in the pressure accumulating unit. Adjusting the hydraulic pressure of the brake fluid to a hydraulic pressure corresponding to the master pressure, and a mechanical pressure adjusting section capable of outputting the adjusted hydraulic pressure to the servo chamber, and the brake The liquid discharge control unit is pressure-accumulated in the pressure accumulating unit when the servo pressure is regulated by the pressure regulating unit according to the master pressure and the vehicle speed is less than the predetermined speed. Drain the brake fluid.

The vehicular braking control apparatus according to claim 5 is a vehicular braking control apparatus that includes a pressure accumulating unit that accumulates brake fluid, and pressurizes a wheel cylinder of the vehicle using the hydraulic pressure of the accumulating unit, When the brake fluid discharge unit capable of discharging the brake fluid accumulated in the pressure storage unit, a vehicle speed acquisition unit that acquires the vehicle speed of the vehicle, and the vehicle speed acquired by the vehicle speed acquisition unit are less than a predetermined speed In addition, a brake fluid discharge control unit that discharges the brake fluid accumulated in the pressure accumulating unit by the brake fluid discharge unit, a cylindrical housing closed at the front, and a master chamber are partitioned in front of itself. An output piston disposed in the housing, and a rear chamber disposed in the housing behind the output piston so that a separation chamber is defined behind the output piston. A master cylinder having an input piston connected to a brake operation member and moved by an operation force applied to the brake operation member; and an open state in which the brake fluid flows into and out of the separation chamber, or the separation chamber A separation chamber opening / closing section that switches to a sealed state in which the brake fluid does not flow in and out, and the brake fluid discharge control section is configured such that the separation chamber is in the sealed state and the vehicle speed is less than the predetermined speed. In addition, the brake fluid accumulated in the pressure accumulator is discharged by the brake fluid discharger.

The braking control device for a vehicle according to claim 6 is a braking control device for a vehicle that includes a pressure accumulating unit that accumulates brake fluid and pressurizes a wheel cylinder of the vehicle using the fluid pressure of the accumulating unit, When the brake fluid discharge unit capable of discharging the brake fluid accumulated in the pressure storage unit, a vehicle speed acquisition unit that acquires the vehicle speed of the vehicle, and the vehicle speed acquired by the vehicle speed acquisition unit are less than a predetermined speed In addition, a brake fluid discharge control unit that discharges the brake fluid accumulated in the pressure storage unit by the brake fluid discharge unit, and a reaction force that generates a reaction force pressure corresponding to a reaction force that resists the operation of the brake operation member A chamber is formed between the reaction force chamber and the reservoir, the master cylinder generating a master pressure corresponding to the amount of operation of the brake operation member; A control valve for controlling the flow of the fluid, and the brake fluid discharge controller is allowed to flow the brake fluid from the reaction force chamber to the reservoir by the control valve, and the vehicle speed Is less than the predetermined speed, the brake fluid accumulated in the pressure accumulating portion is discharged by the brake fluid discharging portion.

The braking control device for a vehicle according to claim 7 is a braking control device for a vehicle that includes a pressure accumulating portion that accumulates brake fluid, and pressurizes a wheel cylinder of the vehicle using the fluid pressure of the accumulating portion, When the brake fluid discharge unit capable of discharging the brake fluid accumulated in the pressure storage unit, a vehicle speed acquisition unit that acquires the vehicle speed of the vehicle, and the vehicle speed acquired by the vehicle speed acquisition unit are less than a predetermined speed Further, the brake fluid discharge control unit that discharges the brake fluid accumulated in the pressure accumulating unit by the brake fluid discharge unit, and the output piston is driven by the servo pressure in the servo chamber to move, and the movement of the output piston The master cylinder configured to change the master pressure in the master chamber, and the pressure accumulating unit and the servo chamber communicate with each other, and the pressure accumulating unit accumulates the pressure. Adjusting the hydraulic pressure of the rake liquid to a hydraulic pressure corresponding to the pilot pressure in the pilot chamber and outputting it to the servo chamber, provided between the pressure accumulator and the pilot chamber, the pressure accumulator A first control valve that controls the flow of the brake fluid from the pilot section to the pilot chamber, and a first control valve that is provided between the pilot chamber and the reservoir, and that controls the flow of the brake fluid from the pilot chamber to the reservoir. The brake fluid discharge part includes the first control valve and the second control valve, and the brake fluid discharge control part opens the first control valve and the second control valve. The brake fluid accumulated in the pressure accumulating section is discharged to the reservoir.

  According to the braking control device for a vehicle according to claim 1, when the vehicle speed is less than a predetermined speed, that is, when a relatively large braking force is not required (for example, during low-speed traveling or stopping), the pressure accumulation is performed. The brake fluid accumulated in the portion (hereinafter referred to as “brake fluid in the pressure accumulation portion”) can be discharged to reduce the fluid pressure in the pressure accumulation portion. As a result, the hydraulic pressure of the pressure accumulating unit necessary for braking can be secured, and the durability of the vehicle braking control device can be enhanced.

In the braking control device for a vehicle according to claim 1, when the hydraulic pressure of the pressure accumulating portion becomes lower than the pump operation start hydraulic pressure, the pump starts discharging the brake fluid to the pressure accumulating portion, and the hydraulic pressure of the pressure accumulating portion is pumped. When the stop hydraulic pressure is exceeded, the pump stops discharging brake fluid to the pressure accumulator. Therefore, the hydraulic pressure level of the pressure accumulating unit is equal to or higher than the pump operation start hydraulic pressure and lower than the pump operation stop hydraulic pressure.

  Further, when the vehicle speed is lower than the predetermined speed, the pump operation start hydraulic pressure and the pump operation stop hydraulic pressure are set lower than when the vehicle speed is higher than the predetermined speed. Therefore, the hydraulic pressure level of the pressure accumulating unit when a relatively large braking force is not required is relatively higher than the pump operation starting hydraulic pressure which is smaller than the pump operation starting hydraulic pressure when a relatively large braking force is required. The pump operation stop hydraulic pressure is smaller than the pump operation stop hydraulic pressure when the braking force is required. In short, the hydraulic pressure level of the pressure accumulating portion when a relatively large braking force is not required can be made lower than the hydraulic pressure level of the pressure accumulating portion when a relatively large braking force is required.

Further, in the brake control device for a vehicle according to claim 1, when the vehicle speed is less than a predetermined speed, the brake fluid in the accumulator unit is discharged. Therefore, according to the braking control device for a vehicle according to claim 1 , when a relatively large braking force is not required, the hydraulic pressure level of the pressure accumulating portion is quickly reduced by discharging the brake fluid of the pressure accumulating portion. Thus, the durability of the vehicle braking control device can be improved.

In the vehicle brake control device according to claim 2, when the vehicle speed is less than a predetermined speed, the brake fluid in the pressure accumulating portion is discharged until the fluid pressure in the pressure accumulating portion becomes less than the pump operation stop fluid pressure. Is done. Therefore, the hydraulic pressure level of the pressure accumulating unit when a relatively large braking force is not required can be reduced more quickly.

  Here, if the brake fluid in the pressure accumulating portion is discharged until the fluid pressure in the pressure accumulating portion becomes less than the pump operation start fluid pressure, the pump operates until the fluid pressure in the pressure accumulating portion becomes equal to or higher than the pump operation stop fluid pressure. For this reason, it takes time until the hydraulic pressure in the pressure accumulating section becomes lower than the pump operation stop hydraulic pressure and higher than the pump operation start hydraulic pressure.

On the other hand, in the braking control device for a vehicle according to claim 3 , the brake fluid in the pressure accumulating portion is discharged until the fluid pressure in the pressure accumulating portion is less than the pump operation stop fluid pressure and equal to or higher than the pump operation start fluid pressure. . As a result, the hydraulic pressure level of the pressure accumulating unit when a relatively large braking force is not required can be reduced more rapidly.

In the vehicle brake control device according to the fourth aspect , it is conceivable that the master pressure becomes high when the hydraulic pressure corresponding to the master pressure is output to the servo chamber by the pressure adjusting unit. That is, when the output piston moves forward by the brake operation and the master pressure increases, the servo pressure increases due to the increase in the master pressure. Therefore, unless the brake operation force is reduced, the output piston further advances and the master pressure increases. It is conceivable that the master pressure is increased by repeating such an increase cycle of the master pressure.

In contrast, in the vehicle braking control device according to claim 4, when the hydraulic pressure corresponding to the master pressure is output to the servo chamber by the pressure adjusting unit, and the vehicle speed is less than the predetermined speed. The brake fluid in the pressure accumulator is discharged. Thereby, it can suppress that a master pressure becomes high by repeating the increase cycle of the said master pressure.

In the vehicle brake control device according to the fifth aspect , when the separation chamber is sealed, the brake fluid in the separation chamber becomes a rigid body, so that the output piston moves together with the input piston. In this case, since the operation force with respect to the brake operation member acts on the output piston as it is, it is conceivable that the master pressure becomes high.

On the other hand, in the vehicle braking control device according to the fifth aspect , the brake fluid in the pressure accumulating portion is discharged when the separation chamber is in a sealed state and the vehicle speed is less than a predetermined speed. Thereby, it can suppress that a master pressure becomes high resulting from a separation chamber becoming a sealing state.

In the vehicle brake control device according to claim 6, when the flow of the brake fluid from the reaction force chamber to the reservoir is allowed, the reaction force against the operation of the brake operation member is reduced, so that the master pressure is high. It is possible to become.

In contrast, in the vehicle brake control device according to the sixth aspect , the flow of the brake fluid from the reaction force chamber to the reservoir is permitted by the control valve, and the vehicle speed is less than the predetermined speed. The brake fluid in the pressure accumulator is discharged. Thereby, it is possible to suppress the master pressure from becoming high due to the fact that the flow of the brake fluid from the reaction force chamber to the reservoir is permitted.

According to the vehicle brake control device according to claim 7 , the first control valve and the second control valve are opened, so that the brake fluid of the pressure accumulating portion passes through the pilot chamber of the pressure regulating portion from the pressure accumulating portion. Can be discharged into the reservoir. In this way, the first control valve and the second control valve that control the pilot pressure can also be used as the brake fluid discharge portion, so that the cost of the vehicle brake control device can be reduced.

It is a fragmentary sectional view showing an example of composition of a brake control device for vehicles. FIG. 2 is a partial cross-sectional view illustrating an example of a configuration of a regulator 44 in FIG. 1. It is explanatory drawing which shows an example of the relationship between pedal depression force Ft and master pressure Pm. It is a block diagram which shows an example of the control block of pressure accumulation control. It is explanatory drawing which shows an example of the time-dependent change of the accumulator pressure Pac. It is a flowchart which shows an example of the control procedure of pressure accumulation control. It is explanatory drawing which shows an example of a time-dependent change of the drive current of the pressure increase valve, the pedal stroke Fs, the pedal depression force Ft, the accumulator pressure Pac, the master pressure Pm, and the servo pressure Ps.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each figure is a conceptual diagram and does not define the dimensions of the detailed structure.
(1) Configuration of braking control device for vehicle

  FIG. 1 is a partial cross-sectional view showing an example of the configuration of a vehicle braking control device. As shown in the figure, the braking control device for a vehicle of this embodiment mainly includes a master cylinder 1, a reaction force generator 2, a control valve 22, a control valve 3, and a servo pressure generator 4. The brake device 5, the brake ECU 6, and various sensors 72 to 76 that can communicate with the brake ECU 6 are provided. Note that a known hybrid ECU (not shown) is communicably connected to the brake ECU 6.

(Master cylinder 1)
The master cylinder 1 supplies brake fluid to the brake device 5, and mainly includes a main cylinder 11, a cover cylinder 12, an input piston 13, a first master piston 14, a second master piston 15, have.

  The main cylinder 11 is a bottomed substantially cylindrical cylinder having one end opened and a bottom surface on the other end. The main cylinder 11 corresponds to a “housing”. Hereinafter, the master cylinder 1 will be described with the opening side of the main cylinder 11 as the rear (arrow A1 direction) and the bottom side of the main cylinder 11 as the front (arrow A2 direction). The main cylinder 11 has an inner wall portion 111 for separating the opening side (arrow A1 direction side) and the bottom surface side (arrow A2 direction side) of the main cylinder 11 inside. A through hole 111a is formed in the center of the inner wall 111 to penetrate in the axial direction (front-rear direction).

  Further, inside the main cylinder 11, there are small-diameter portions 112 (front) and 113 (rear) having a smaller inner diameter in front of the inner wall portion 111. That is, the small diameter portions 112 and 113 protrude from a part of the entire circumference of the inner peripheral surface of the main cylinder 11 in the axial direction. In the main cylinder 11, a first master piston 14 and a second master piston 15, which will be described later, are arranged so as to be slidable in the axial direction. The first master piston 14 and the second master piston 15 correspond to “output pistons”. Note that ports and the like that allow communication between the inside and the outside will be described later.

  The cover cylinder 12 has a substantially cylindrical cylinder portion 121 and a cup-shaped compression spring 122. The cylinder portion 121 is disposed on the rear end side of the main cylinder 11 and is fitted coaxially to the opening of the main cylinder 11. The inner diameter of the front part 121a of the cylinder part 121 is larger than the inner diameter of the rear part 121b. Further, the inner diameter of the front portion 121a is larger than the inner diameter of the through hole 111a of the inner wall portion 111.

  The compression spring 122 is assembled to the rear end portion of the main cylinder 11 and the outer peripheral surface of the cylinder portion 121 so as to close the opening of the main cylinder 11 and the rear end side opening of the cylinder portion 121. On the bottom wall of the compression spring 122, a flange 122a of the operation rod 10a is formed. The compression spring 122 is made of an elastic member that can expand and contract in the axial direction, and its bottom wall is urged rearward.

  The input piston 13 is a piston that slides in the cover cylinder 12 in accordance with the operation of the brake pedal 10. The input piston 13 is a bottomed substantially cylindrical piston having a bottom surface at the front and an opening at the rear. The bottom wall 131 constituting the bottom surface of the input piston 13 has a larger diameter than other portions of the input piston 13. The input piston 13 is disposed so that the bottom wall 131 is positioned at the rear end of the front portion of the cylinder portion 121. The input piston 13 is slidable in the axial direction and liquid-tightly disposed at the rear portion 121b of the cylinder portion 121.

  Inside the input piston 13, an operation rod 10a and a pivot 10b of the brake pedal 10 are installed. The operation rod 10 a protrudes outside through the opening of the input piston 13 and the flange 122 a of the cover member 122, and is connected to the brake pedal 10. The operating rod 10a moves in conjunction with the operation of the brake pedal 10, and moves forward while pressing the compression spring 122 in the axial direction when the brake pedal 10 is depressed. As the operating rod 10a advances, the input piston 13 also advances. The brake pedal 10 corresponds to a “brake operation member”.

  The first master piston 14 is slidably disposed in the main cylinder 11 in the axial direction. Specifically, the first master piston 14 has a first main body portion 141 and a protruding portion 142. The first main body 141 is coaxially disposed in front of the inner wall 111 in the main cylinder 11. The first main body 141 is formed in a substantially cylindrical shape with a bottom having an opening at the front and a flange 141a at the rear. That is, the 1st main-body part 141 has the collar part 141a and the surrounding wall part 141b.

  The flange 141a is slidable in the axial direction on the main cylinder 11 in front of the inner wall 111 and is disposed in a liquid-tight manner. The peripheral wall portion 141b is formed in a cylindrical shape having a smaller diameter than the flange portion 141a, and extends coaxially forward from the front end surface of the flange portion 141a. The front portion of the peripheral wall portion 141b is slidable in the axial direction and liquid-tightly arranged on the small-diameter portion 112. A rear portion of the peripheral wall portion 141 b is separated from the inner peripheral surface of the main cylinder 11.

  The protruding portion 142 is a columnar portion that protrudes backward from the center of the end surface of the flange portion 141 a of the first main body portion 141. The protruding portion 142 is slidable in the axial direction and liquid-tightly arranged in the through hole 111a of the inner wall portion 111. The rear portion of the protruding portion 142 is located inside the cylinder portion 121 through the through hole 111a. A rear portion of the protruding portion 142 is separated from the inner peripheral surface of the cylinder portion 121. The rear end surface of the protrusion 142 is separated from the bottom wall 131 of the input piston 13 by a predetermined distance. The first master piston 14 is urged rearward by an urging member 143 made of a spring or the like.

  Here, the “servo chamber 1 </ b> A” is defined by the rear end surface of the flange 141 a of the first main body 141, the front end surface of the inner wall 111, the inner peripheral surface of the main cylinder 11, and the outer peripheral surface of the protruding portion 142. The “separating chamber 1 </ b> B” is defined by the rear end surface of the inner wall 111, the outer surface of the input piston 131, the inner peripheral surface of the front portion 121 a of the cylinder portion 121, and the outer surface of the protruding portion 142. Further, the “reaction force chamber 1 </ b> C” is defined by the rear end surface of the small diameter portion 112 (including the seal member 91), the outer peripheral surface of the first master piston 14, and the inner peripheral surface of the main cylinder 11.

  The second master piston 15 is coaxially disposed in front of the first master piston 14 in the main cylinder 11. The second master piston 15 is formed in a substantially cylindrical shape with a bottom having an opening in the front and a bottom wall 151 in the rear. That is, the second master piston 15 has a bottom wall 151 and a peripheral wall 152 having the same diameter as the bottom wall 151. The bottom wall 151 is disposed between the small diameter portions 112 and 113 in front of the first master piston 14. A rear portion of the second master piston 15 including the bottom wall 151 is separated from the inner peripheral surface of the main cylinder 11. The peripheral wall 152 is cylindrical and extends coaxially from the bottom wall 151 to the front. The peripheral wall portion 152 is slidable in the axial direction and liquid-tightly disposed on the small diameter portion 113. The second master piston 15 is urged rearward by an urging member 153 made of a spring or the like.

  Here, the second master piston 15 outer surface, the first master piston 14 front end surface, the first master piston inner surface, the small diameter portion 112 front end surface (including the seal member 92), the small diameter portion 113 rear end surface (including the seal member 93). ) And the inner peripheral surface of the main cylinder 11 between the small-diameter portions 112 and 113 define a “first hydraulic pressure chamber 1D”. Further, the main cylinder 11 inner bottom surface 111d, the second master piston 15 front end surface, the second master piston 15 inner surface, the small diameter portion 113 front end surface (including the seal member 94), and the main cylinder 11 inner peripheral surface "second hydraulic pressure". Chamber 1E "is partitioned. The first hydraulic chamber 1D and the second hydraulic chamber 1E are also referred to as “master chambers”.

  The master cylinder 1 is formed with ports 11a to 11i that communicate between the inside and the outside. The port 11 a is formed behind the inner wall 111 in the main cylinder 11. The port 11b is formed opposite to the port 11a at the same position in the axial direction as the port 11a. The port 11 a and the port 11 b communicate with each other via a space between the inner peripheral surface of the main cylinder 11 and the outer peripheral surface of the cylinder part 121. The port 11a is connected to the pipe 161. The port 11b is connected to the reservoir 171. That is, the port 11a communicates with the reservoir 171.

  Further, the port 11 b communicates with the separation chamber 1 </ b> B through a passage 18 formed in the cylinder portion 121 and the input piston 13. The passage 18 is divided when the input piston 13 moves forward. That is, when the input piston 13 moves forward, the separation chamber 1B and the reservoir 171 are separated.

  The port 11c is formed in front of the port 11a and connects the separation chamber 1B and the pipe 162. The port 11d is formed in front of the port 11c and connects the servo chamber 1A and the pipe 163. The port 11e is formed in front of the port 11d and communicates the reaction force chamber 1C and the pipe 164.

  The port 11f is formed between the seal members 91 and 92 of the small-diameter portion 112, and communicates the reservoir 172 and the inside of the main cylinder 11. The port 11 f communicates with the first hydraulic chamber 1 </ b> D via a passage 144 formed in the first master piston 14. The passage 144 is formed at a position slightly rearward of the seal member 92 so that the port 11f and the first hydraulic chamber 1D are separated when the first master piston 14 moves forward.

  The port 11g is formed in front of the port 11f and communicates the first hydraulic chamber 1D and the pipe 51. The port 11 h is formed between the seal members 93 and 94 of the small diameter portion 113 and communicates the reservoir 173 and the inside of the main cylinder 11. The port 11g communicates with the second hydraulic chamber 1E via a passage 154 formed in the second master piston 15. The passage 154 is formed at a position slightly rearward of the seal member 94 so that the port 11g and the second hydraulic chamber 1E are separated when the second master piston 15 moves forward. The port 11i is formed in front of the port 11h, and communicates the second hydraulic chamber 1E and the pipe 52.

  Further, in the master cylinder 1, a seal member (black circle portion in the drawing) such as an O-ring is appropriately disposed. The seal members 91 and 92 are disposed in the small-diameter portion 112 and are in liquid-tight contact with the outer peripheral surface of the first master piston 14. Similarly, the seal members 93 and 94 are disposed in the small diameter portion 113 and are in liquid-tight contact with the outer peripheral surface of the second master piston 15. A seal member is also arranged between the input piston 13 and the cylinder part 121. The brake pedal 10 is provided with a stroke sensor 72. The stroke sensor 72 is a sensor that detects the stroke amount (operation amount by the driver) of the brake pedal 10, and the detection result is transmitted to the brake ECU 6.

(Reaction force generator 2)
The reaction force generator 2 includes a stroke simulator 21. The stroke simulator 21 is a device that generates a reaction force pressure Pr in the reaction force chamber 1C via the separation chamber 1B according to the stroke amount of the brake pedal 10. Generally, in the stroke simulator 21, a piston 212 is slidably fitted in a cylinder 211, and a simulator liquid chamber 214 is formed on the front side of the piston 212 urged forward by a compression spring 213. The stroke simulator 21 is connected to the reaction force chamber 1C via the pipe 164 and the port 11e, and is connected to the control valve 22 and the control valve 3 via the pipe 164.

(Control valve 22)
The control valve 22 is a normally closed electromagnetic valve (linear valve), and opening and closing of the control valve 22 is controlled by the brake ECU 6. The control valve 22 is connected to the pipe 164 and the pipe 162, and connects or disconnects the pipes 162 and 164. That is, the control valve 22 is an on-off valve that connects or disconnects the separation chamber 1B and the reaction force chamber 1C. The control valve 22 corresponds to a “separation chamber opening / closing part”.

  The hydraulic pressure sensor 73 is a sensor that mainly detects the pressure in the separation chamber 1 </ b> B and the reaction force chamber 1 </ b> C, and is connected to the pipe 164. The hydraulic pressure sensor 73 detects the pressure in the separation chamber 1B and the reaction force chamber 1C when the control valve 22 is open, and detects the pressure in the reaction force chamber 1C when the control valve 22 is closed.

(Control valve 3)
The control valve 3 is a normally open electromagnetic valve, and opening and closing of the control valve 3 is controlled by the brake ECU 6. The control valve 3 is connected to the pipe 164 and the pipe 161, and connects or disconnects the pipes 161 and 164. When the control valve 22 is in the open state, the control valve 3 can connect or disconnect the separation chamber 1 </ b> B and the reaction force chamber 1 </ b> C and the reservoir 171. When the control valve 22 is in the closed state, the control valve 3 can connect or disconnect the reaction force chamber 1 </ b> C and the reservoir 171.

(Control of control valve 22 and control valve 3)
Here, control by the brake ECU 6 of the control valve 3 and the control valve 22 at the time of brake operation will be described. When the brake pedal 10 is depressed, the input piston 13 moves forward, the passage 18 is divided, and the reservoir 171 and the separation chamber 1B are shut off. At the same time, the control valve 3 changes from the open state to the closed state, and the control valve 22 changes from the closed state to the open state. By closing the control valve 3, the reaction force chamber 1C and the reservoir 171 are shut off. When the control valve 22 is opened, the separation chamber 1B and the reaction force chamber 1C communicate with each other. That is, the separation piston 1 </ b> B and the reaction force chamber 1 </ b> C are shut off from the reservoir 171 by the input piston moving forward and the control valve 3 being closed. Then, the stroke simulator 21 generates a reaction force pressure Pr corresponding to the driver's pedal stroke amount in the separation chamber 1B and the reaction force chamber 1C. At this time, the brake fluid of the same amount as the amount of fluid flowing in and out of the separation chamber 1B according to the movement of the first master piston 14 and the second master piston 15 flows into and out of the reaction force chamber 1C.

(Servo pressure generator 4)
The servo pressure generator 4 mainly includes a pressure reducing valve 41, a pressure increasing valve 42, a pressure supply unit 43, and a regulator 44. The pressure reducing valve 41 is a normally open electromagnetic valve, and the flow rate is controlled by the brake ECU 6. One side of the pressure reducing valve 41 is connected to the pipe 161 via the pipe 411, and the other side of the pressure reducing valve 41 is connected to the pipe 413. That is, one side of the pressure reducing valve 41 communicates with the reservoir 171 through the pipes 411 and 161 and the ports 11a and 11b. The pressure increasing valve 42 is a normally closed electromagnetic valve, and the flow rate is controlled by the brake ECU 6. One of the pressure increasing valves 42 is connected to the pipe 421, and the other of the pressure increasing valves 42 is connected to the pipe 422.

  The pressure supply unit 43 can supply high-pressure brake fluid to the regulator 44 based on an instruction from the brake ECU 6. The pressure supply unit 43 mainly includes an accumulator 431, a pump 432, a motor 433, and a reservoir 434.

  The accumulator 431 accumulates the hydraulic pressure generated by the pump 432. The accumulator 431 corresponds to a “pressure accumulator”. The accumulator 431 is connected to the regulator 44, the hydraulic pressure sensor 75, and the pump 432 through a pipe 431a. The pump 432 is connected to the motor 433 and the reservoir 434. The pump 432 supplies the brake fluid stored in the reservoir 434 to the accumulator 431 when the motor 433 is driven. The hydraulic pressure sensor 75 is a sensor that detects the hydraulic pressure of the brake fluid accumulated in the accumulator 431. The fluid pressure detected by the fluid pressure sensor 75 is referred to as accumulator pressure Pac. The hydraulic pressure sensor 75 corresponds to a “hydraulic pressure acquisition unit”.

  When the hydraulic pressure sensor 75 detects that the accumulator pressure Pac has dropped below a predetermined value, the motor 433 is driven based on a control signal from the brake ECU 6, and the pump 432 supplies brake fluid to the accumulator 431. Pressure energy is supplied to the accumulator 431. The accumulation control of the accumulator pressure Pac will be described later.

  The regulator 44 is obtained by adding a sub piston 446 mainly to a general regulator. FIG. 2 is a partial cross-sectional view showing an example of the configuration of the regulator 44 of FIG. As shown in the figure, the regulator 44 mainly includes a cylinder 441, a ball valve 442, an urging portion 443, a valve seat portion 444, a control piston 445, and a sub piston 446. The regulator 44 corresponds to a “pressure adjusting unit”.

  The cylinder 441 includes a substantially bottomed cylindrical cylinder case 441a having a bottom surface on one side (in the direction of arrow A3) and a lid member 441b that closes the opening side (in the direction of arrow A4) of the cylinder case 441a. In the figure, the lid member 441b is formed in a U-shaped cross section, but in this specification, the lid member 441b is described as a columnar shape. That is, the part which closes the opening part of cylinder case 441a is demonstrated as the cover member 441b. The cylinder case 441a is formed with a plurality of ports 4a to 4h for communicating the inside and the outside.

  The port 4a is connected to the pipe 431a. The port 4b is connected to the pipe 422. The port 4c is connected to the pipe 163. The port 4d is connected to the pipe 161 via the pipe 411. The port 4 e is connected to a pipe 424 that leads to the pipe 422 through a relief valve 423. The port 4f is connected to the pipe 413. The port 4g is connected to the pipe 421. The port 4 h is connected to a pipe 511 branched from the pipe 51.

  The ball valve 442 is a ball-type valve and is disposed inside the cylinder 441 on the bottom surface side of the cylinder case 441a (arrow A3 direction side, hereinafter referred to as the cylinder bottom surface side). The urging portion 443 is a spring member that urges the ball valve 442 toward the opening side of the cylinder case 441a (arrow A4 direction side, hereinafter referred to as the cylinder opening side), and is installed on the bottom surface of the cylinder case 441a. . The valve seat portion 444 is a wall member provided on the inner peripheral surface of the cylinder case 441a, and partitions the cylinder opening side (arrow A4 direction side) and the cylinder bottom surface side (arrow A3 direction side). A through passage 444a is formed in the center of the valve seat portion 444 to communicate the partitioned cylinder opening side (arrow A4 direction side) and the cylinder bottom side (arrow A3 direction side). The valve seat portion 444 holds the ball valve 442 from the cylinder opening side (arrow A4 direction side) in such a manner that the biased ball valve 442 closes the through passage 444a.

  A space defined by the ball valve 442, the urging portion 443, the valve seat portion 444, and the inner peripheral surface of the cylinder case 441a on the cylinder bottom surface side (arrow A3 direction side) is referred to as a “first chamber 4A”. The first chamber 4A is filled with brake fluid, connected to the pipe 431a via the port 4a, and connected to the pipe 422 via the port 4b.

  The control piston 445 includes a substantially cylindrical main body 445a and a substantially cylindrical protrusion 445b having a smaller diameter than the main body 445a. In the cylinder 441, the main body 445a is disposed coaxially and liquid-tightly on the cylinder opening side (arrow A4 direction side) of the valve seat 444 so as to be slidable in the axial direction. The main body 445a is urged toward the cylinder opening side (arrow A4 direction side) by an urging member (not shown). A passage 445c extending in the circumferential direction (in the direction of arrow A5) with both ends opened to the peripheral surface of the main body 445a is formed at the approximate center of the main body 445a in the cylinder axis direction. A port 4d is formed on a part of the inner peripheral surface of the cylinder 441 corresponding to the arrangement position of the opening of the passage 445c, and is recessed in a concave shape to form a “third chamber 4C” by the main body 445a.

  The protruding portion 445b protrudes from the center of the cylinder bottom surface side (arrow A3 direction side) end surface of the main body portion 445a to the cylinder bottom surface side (arrow A3 direction side). The diameter of the protruding portion 445 b is smaller than the through passage 444 a of the valve seat portion 444. The protruding portion 445b is arranged coaxially with the through passage 444a. The tip of the protruding portion 445b is separated from the ball valve 442 by a predetermined distance toward the cylinder opening side (arrow A4 direction side). The protrusion 445b is formed with a passage 445d that extends in the cylinder axial direction and opens in the center of the end surface of the protrusion 445b on the cylinder bottom surface side (arrow A3 direction side). The passage 445d extends into the main body 445a and is connected to the passage 445c.

  The space defined by the cylinder bottom surface (arrow A3 direction side) end surface of the main body 445a, the outer surface of the protrusion 445b, the inner peripheral surface of the cylinder 441, the valve seat 444 and the ball valve 442 is referred to as a “second chamber 4B”. To do. The second chamber 4B communicates with the ports 4d and 4e via the passages 445c and 445d and the third chamber 4C.

  The sub piston 446 has a sub main body 446a, a first protrusion 446b, and a second protrusion 446c. The sub main body 446a is formed in a substantially cylindrical shape. In the cylinder 441, the sub main body 446a is disposed coaxially and liquid-tightly on the cylinder opening side (arrow A4 direction side) of the main body 445a so as to be slidable in the axial direction.

  The first projecting portion 446b has a substantially cylindrical shape having a smaller diameter than the sub main body portion 446a, and projects from the center of the end surface of the sub main body portion 446a on the cylinder bottom surface side (arrow A3 direction side). The first projecting portion 446b is in contact with the cylinder opening side (arrow A4 direction side) end surface of the main body portion 445a. The 2nd protrusion part 446c is the same shape as the 1st protrusion part 446b, and protrudes from the end surface center of the cylinder opening side (arrow A4 direction side) of the sub main body part 446a. The second protrusion 446c is in contact with the lid member 441b.

  The sub-main body 446a is partitioned by the cylinder bottom surface (arrow A3 direction side) end surface, the first protrusion 446b outer surface, the control piston 445 cylinder opening side (arrow A4 direction side) end surface, and the cylinder 441 inner peripheral surface. This space is referred to as “pilot room 4D”. The pilot chamber 4D communicates with the pressure reducing valve 41 via the port 4f and the pipe 413, and communicates with the pressure increasing valve 42 via the port 4g and the pipe 421.

  On the other hand, a space defined by the end surface of the sub main body 446a on the cylinder opening side (arrow A4 direction side), the outer surface of the second protrusion 446c, the lid member 441b and the inner peripheral surface of the cylinder 441 is referred to as “fourth chamber 4E”. And The fourth chamber 4E communicates with the port 11g via the port 4h and the pipes 511 and 51. Each chamber 4A-4E is filled with brake fluid. The hydraulic pressure sensor 74 is a sensor for detecting the pressure (servo pressure Ps) in the servo chamber 1 </ b> A, and is connected to the pipe 163.

(Brake device 5)
Wheel cylinders 541 to 544 communicate with the first hydraulic chamber 1D and the second hydraulic chamber 1E that generate the master pressure Pm through pipes 51 and 52 and an ABS 53, respectively. The wheel cylinders 541 to 544 constitute the brake device 5 for the wheels 5FR to 5RL. Specifically, a known ABS (Antilock Break System) 53 is connected to the port 11g of the first hydraulic chamber 1D and the port 11i of the second hydraulic chamber 1E via pipes 51 and 52, respectively. . Wheel cylinders 541 to 544 for braking the wheels 5FR to 5RL are connected to the ABS 53.

  Here, the configuration of one of the four wheels (5FR) of the ABS 53 will be described. Since the other wheels have the same configuration, the description thereof is omitted. The ABS 53 includes a holding valve 531, a pressure reducing valve 532, a reservoir 533, a pump 534, and a motor 535. The holding valve 531 is a normally-open electromagnetic valve, and opening / closing thereof is controlled by the brake ECU 6. The holding valve 531 is arranged such that one is connected to the pipe 52 and the other is connected to the wheel cylinder 541 and the pressure reducing valve 532. That is, the holding valve 531 is an input valve of the ABS 53.

  The pressure reducing valve 532 is a normally closed electromagnetic valve, and opening / closing thereof is controlled by the brake ECU 6. One of the pressure reducing valves 532 is connected to the wheel cylinder 541 and the holding valve 531, and the other is connected to the reservoir 533. When the pressure reducing valve 532 is opened, the wheel cylinder 541 and the reservoir 533 communicate with each other.

  The reservoir 533 can store brake fluid, and is connected to the pipe 52 via a pressure reducing valve 532 and a pump 534. The pump 534 is arranged such that the suction port is connected to the reservoir 533 and the discharge port is connected to the pipe 52 via the check valve z. The check valve z here allows the flow from the pump 534 to the pipe 52 (second hydraulic pressure chamber 1E) and restricts the flow in the reverse direction. The pump 534 is driven by the operation of a motor 535 according to a command from the brake ECU 6. In the ABS control decompression mode, the pump 535 sucks the brake fluid in the wheel cylinder 541 or the brake fluid stored in the reservoir 533 and returns it to the second hydraulic pressure chamber 1E. Note that a damper (not shown) is disposed on the upstream side of the pump 534 in order to reduce the pulsation of the brake fluid discharged from the pump 534.

  The ABS 53 includes a vehicle speed sensor 76 that detects a wheel speed. The detection result detected by the vehicle speed sensor 76 is output to the brake ECU 6. The vehicle speed detected by the vehicle speed sensor 76 is referred to as a vehicle speed VS. The vehicle speed sensor 76 corresponds to a “vehicle speed acquisition unit”.

  In the ABS 53 configured as described above, the brake ECU 6 switches and controls the opening and closing of the electromagnetic valves 531 and 532 based on the master pressure Pm, the state of the wheel speed, and the longitudinal acceleration, and operates the motor 535 as necessary. ABS control (anti-lock brake control) is performed to adjust the brake fluid pressure applied to the wheel cylinder 541, that is, the braking force applied to the wheel 5FR. The ABS 53 adjusts the amount of brake fluid supplied from the master cylinder 1 and the supply timing based on an instruction from the brake ECU 6 and supplies the adjusted brake fluid to the wheel cylinders 541 to 544.

  In the linear mode to be described later, the accumulator pressure Pac sent from the accumulator 431 of the servo pressure generator 4 is controlled by the pressure increasing valve 42 and the pressure reducing valve 41, and the servo pressure Ps is generated in the servo chamber 1A. 14 and the second master piston 15 move forward to pressurize the first hydraulic chamber 1D and the second hydraulic chamber 1E. The hydraulic pressure (master pressure Pm) in the first hydraulic pressure chamber 1D and the second hydraulic pressure chamber 1E is supplied from the ports 11g and 11i to the wheel cylinders 541 to 544 as the master pressure Pm via the pipes 51 and 52 and the ABS 53. Thus, a hydraulic braking force is applied to the wheels 5FR to 5RL. The pressure reducing valve 41, the control valve 3, the pressure adjusting unit 43, and the ABS 53 are appropriately provided with a check valve z.

(Brake ECU 6)
The brake ECU 6 is an electronic control unit that communicates with the various sensors 72 to 76 and controls the electromagnetic valves 22, 3, 41, 42, 531, 532, motors 433, 535, and the like. The brake ECU 6 stores two control modes, a linear mode and a REG mode. The linear mode is a normal brake control. The control valve 22 is opened and the control valve 3 is closed, and the pressure reducing valve 41 and the pressure increasing valve 42 are controlled to control the servo pressure Ps in the servo chamber 1A. It is a mode to do.

  The REG mode has a first REG mode and a second REG mode. The first REG mode is a mode when the pressure reducing valve 41, the pressure increasing valve 42, the control valve 22 and the electromagnetic valve 3 of the control valve 3 are in a non-energized state (maintenance maintained) due to a failure or the like. The second REG mode is a mode for controlling the servo pressure Ps of the servo chamber 1A by controlling the pressure reducing valve 41 and the pressure increasing valve 42 with the control valve 22 closed or the control valve 3 opened. That is, the second REG mode differs from the linear mode in that the control valve 22 and the control valve 3 are opened and closed, and the second REG mode is different from the first REG mode in that the pressure reducing valve 41 and the pressure increasing valve 42 can be controlled.

(Linear mode)
When the brake pedal 10 is not depressed, the state as described above, that is, the state where the ball valve 442 blocks the through passage 444a of the valve seat portion 444 is obtained. Further, the pressure reducing valve 41 is in an open state, and the pressure increasing valve 42 is in a closed state. That is, the first chamber 4A and the second chamber 4B are isolated.

  The second chamber 4B communicates with the servo chamber 1A via the pipe 163 and is kept at the same pressure. The second chamber 4B communicates with the third chamber 4C through passages 445c and 445d of the control piston 445. Therefore, the second chamber 4B and the third chamber 4C communicate with the reservoir 171 through the pipes 414 and 161. One of the pilot chambers 4 </ b> D is closed by the pressure increasing valve 42, and the other is in communication with the reservoir 171 through the pressure reducing valve 41. The pilot chamber 4D and the second chamber 4B are kept at the same pressure. The fourth chamber 4E communicates with the first hydraulic chamber 1D via the pipes 511 and 51 and is maintained at the same pressure.

  From this state, when the brake pedal 10 is depressed by the driver, first, regenerative braking is performed. The brake ECU 6 separates the required braking force based on the driver's brake operation amount into a hydraulic braking force and a regenerative braking force due to the hydraulic pressure of the brake fluid. The ratio between the hydraulic braking force and the regenerative braking force with respect to the brake operation amount is defined in advance by a map, a table, a relational expression, or the like.

  The hybrid ECU operates the motor as a generator, thereby applying regenerative braking force to the drive wheels to decelerate the vehicle and converting kinetic (rotational) energy into electrical energy. The converted electrical energy is recovered by the battery via the inverter. After predetermined regenerative braking, the brake ECU 6 controls the pressure reducing valve 41, the pressure increasing valve 42 and the motor 433 based on information from the stroke sensor 72. That is, the brake ECU 6 controls the pressure reducing valve 41 in the closing direction and the pressure increasing valve 42 in the opening direction. The brake ECU 6 controls the accumulator pressure Pac of the accumulator 431 by the motor 433.

  By opening the pressure increasing valve 42, the accumulator 431 and the pilot chamber 4D communicate with each other. By closing the pressure reducing valve 41, the pilot chamber 4D and the reservoir 171 are shut off. The pressure (pilot pressure Pd) in the pilot chamber 4D can be increased by the high-pressure brake fluid supplied from the accumulator 431. As the pilot pressure Pd increases, the control piston 445 slides to the cylinder bottom side (arrow A3 direction side). As a result, the tip of the protrusion 445 b of the control piston 445 contacts the ball valve 442, and the passage 445 d is closed by the ball valve 442. Then, the second chamber 4B and the reservoir 171 are shut off.

  Further, when the control piston 445 slides toward the cylinder bottom surface (arrow A3 direction side), the ball valve 442 is pushed and moved by the protrusion 445b toward the cylinder bottom surface side (arrow A3 direction side), and the ball valve 442 is moved. Separated from the valve seat 444. As a result, the first chamber 4A and the second chamber 4B communicate with each other through the through passage 444a of the valve seat portion 444. High pressure brake fluid is supplied from the accumulator 431 to the first chamber 4A, and the pressure in the second chamber 4B increases due to communication.

  As the pressure in the second chamber 4B increases, the pressure in the servo chamber 1A communicating therewith (servo pressure Ps) also increases. As the servo pressure Ps increases, the first master piston 14 moves forward, and the pressure (master pressure Pm) in the first hydraulic pressure chamber 1D increases. And the 2nd master piston 15 also moves forward and the pressure (master pressure Pm) of the 2nd hydraulic pressure chamber 1E rises. Due to the pressure increase in the first hydraulic chamber 1D, high-pressure brake fluid is supplied to the ABS 53 and the fourth chamber 4E. Although the pressure in the fourth chamber 4E rises, the pressure in the pilot chamber 4D (pilot pressure Pd) similarly rises, so the sub-piston 446 does not move. In this way, a high-pressure (master pressure Pm) brake fluid is supplied to the ABS 53, and the brake device 5 is operated to brake the vehicle. The force that advances the first master piston 14 in the linear mode corresponds to the force corresponding to the servo pressure Ps.

  When releasing the brake operation, on the contrary, the pressure reducing valve 41 is opened, the pressure increasing valve 42 is closed, and the reservoir 171 and the pilot chamber 4D are communicated. As a result, the control piston 445 moves backward and returns to the state before the driver operates the brake pedal 10.

(First REG mode)
In the first REG mode, the pressure reducing valve 41, the pressure increasing valve 42, the control valve 22 and the control valve 3 are not energized (controlled), the pressure reducing valve 41 is open, the pressure increasing valve 42 is closed, and the control valve 22 is closed. In the state, the control valve 3 is open. And even after the brake pedal 10 is operated by the driver, the non-energized state (non-control state) is maintained.

  In the first REG mode, when the brake pedal 10 is operated by the driver, the input piston 13 moves forward, the passage 18 is divided, and the separation chamber 1B and the reservoir 171 are shut off. In this state, since the control valve 22 is in a closed state, the separation chamber 1B is in a sealed state. However, the reaction force chamber 1C communicates with the reservoir 171 because the control valve 3 is in the open state.

  Here, when the brake pedal 10 is further depressed, the input piston 13 moves forward, the pressure in the separation chamber 1B (separation pressure Pb) rises, and the first master cylinder 14 moves forward by the separation pressure Pb. At this time, since the pressure reducing valve 41 and the pressure increasing valve 42 are not energized, the servo pressure Ps is not controlled. That is, the first master cylinder 14 moves forward only with a force (separation pressure Pb) corresponding to the operating force of the brake pedal 10. As a result, the volume of the servo chamber 1 </ b> A increases, but the brake fluid is replenished because it communicates with the reservoir 171 via the regulator 44.

  When the first master piston 14 moves forward, the pressures (master pressure Pm) in the first hydraulic chamber 1D and the second hydraulic chamber 1E increase as in the linear mode. And the pressure of 4th chamber 4E also rises by the pressure rise of 1st hydraulic pressure chamber 1D. The sub piston 446 slides to the cylinder bottom side (arrow A3 direction side) due to the pressure increase in the fourth chamber 4E. At the same time, the control piston 445 is pushed by the first protrusion 446b and slides to the cylinder bottom surface side (arrow A3 direction side). As a result, the protruding portion 445b contacts the ball valve 442, and the ball valve 442 is pushed and moved to the cylinder bottom surface side (arrow A3 direction side). That is, the first chamber 4A and the second chamber 4B communicate with each other, the servo chamber 1A and the reservoir 171 are shut off, and high-pressure brake fluid from the accumulator 431 is supplied to the servo chamber 1A.

  As described above, in the first REG mode, when the input piston 13 advances by a predetermined stroke by the driver's operating force of the brake pedal 10, the accumulator 431 and the servo chamber 1A communicate with each other, and the servo pressure Ps increases without control. To do. Then, the first master piston 14 advances more than the operating force of the driver. Thereby, even if each solenoid valve is in a non-energized state, high-pressure brake fluid is supplied to the ABS 53. In the first REG mode, a control map is created so as to generate a braking force that can be safely stopped and stopped in consideration of when the vehicle stops on a slope.

  The force for moving the first master piston 14 forward in the first REG mode corresponds to the force corresponding to the operating force of the driver. That is, the force corresponding to the driver's operating force is the force that advances the first master cylinder 14 only by the driver's operating force, and the servo pressure Ps that is mechanically generated based on the driving of the first master cylinder 14. Force for advancing the piston 14.

(Second REG mode)
The second REG mode is a mode for increasing the braking force when the braking force is reduced due to, for example, a fade phenomenon. In the second REG mode, with the control valve 22 closed or the control valve 3 opened, the pressure reducing valve 41 and the pressure increasing valve 42 are controlled to control the servo pressure Ps in the servo chamber 1A.

  When the braking force decreases due to, for example, a fade phenomenon during traveling in the linear mode, the brake ECU 6 closes the control valve 22 or opens the control valve 3. By closing the control valve 22, the separation chamber 1 </ b> B is hermetically sealed and liquid-tight. By opening the control valve 3, the reaction force chamber 1C is communicated with the reservoir 171 and the reaction force pressure Pr disappears. That is, the first master piston 14 and the second master piston 15 can be moved forward by the driver's pedal depression force Ft, and the pressure applied to the wheel cylinders 541 to 544 can be increased.

The radial sectional area of the separation chamber 1B is S1, the radial sectional area of the first hydraulic chamber 1D and the second hydraulic chamber 1E (master chamber) is S2, and the pressure of the separation chamber 1B is the separation pressure Pb. At this time, the increase ΔPm of the master pressure Pm due to the driver's pedal depression force Ft can be expressed by the following formula 1. For example, if the ratio of the radial cross-sectional area S1 and the radial cross-sectional area S2 is set to 1: 2, the increase ΔPm of the master pressure Pm is ½ of the separation pressure Pb. Further, the master pressure Pm can be expressed by the following equation 2 because the increment ΔPm is added to the servo pressure Ps.
(Equation 1)
ΔPm = Pb × S1 / S2
(Equation 2)
Pm = Ps + Pb × S1 / S2

  FIG. 3 is an explanatory diagram showing an example of the relationship between the pedal effort Ft and the master pressure Pm. The horizontal axis represents the driver's pedal effort Ft, and the vertical axis represents the master pressure Pm. A curve L1 indicates braking in the linear mode, and a curve L2 indicates braking in the second REG mode. In the case of the first REG mode, the characteristics are the same as those of the curve L2. In the linear mode, the control valve 22 is opened and the control valve 3 is closed. Therefore, a reaction force pressure Pr corresponding to the pedal stroke amount of the driver is generated in the reaction force chamber 1C. Thereby, pressurization of the first hydraulic chamber (master chamber) 1D and the second hydraulic chamber (master chamber) 1E by the driver's pedal depression force Ft is suppressed.

  On the other hand, when the control valve 3 is opened in the second REG mode, the reaction force pressure Pr is released. When the control valve 22 is closed, the separation chamber 1B is hermetically sealed and liquid-tight. Therefore, the master chamber is directly pressurized by the driver's pedaling force Ft. Therefore, the master pressure Pm indicated by the curve L2 is larger than the master pressure Pm indicated by the curve L1. The same can be said for the relationship between the first REG mode and the linear mode. In addition, in the same figure, the pedal effort Ft used as an assistance limit is shown by Ft1. The assist limit is a state where the servo pressure Ps reaches the maximum hydraulic pressure that can be generated by the accumulator 431.

  As described above, in the REG mode, when the driver's pedal effort Ft increases, the master pressure Pm increases accordingly, and the master pressure Pm acts on the brake device 5 from the master cylinder 1. Thereby, for example, when the braking force is reduced due to a fade phenomenon or the like, the braking force can be increased. On the other hand, when the vehicle speed VS is low or when the vehicle is stopped, a large braking force is not required as compared with high speed traveling. Therefore, in this embodiment, in such a case, the master pressure Pm supplied from the master cylinder 1 to the brake device 5 is reduced to reduce the load generated on the master cylinder 1, the servo pressure generator 4, the brake device 5, and the like. Let Thereby, these durability can be improved.

  In the REG mode, the master pressure Pm is generated by adding the pressurization amount by the driver's pedal depression force Ft to the servo pressure Ps. Since the pressurization by the driver's pedal depression force Ft cannot be reduced, the servo pressure Ps needs to be reduced in order to reduce the master pressure Pm. That is, it is necessary to reduce the accumulator pressure Pac that generates the servo pressure Ps.

(2) Pressure Accumulation Control of Accumulator 431 FIG. 4 is a block diagram showing an example of a control block for pressure accumulation control. When viewed as a control block, the brake ECU 6 includes a brake fluid discharge control unit 61, a pump control unit 62, and a pump hydraulic pressure setting unit 63. Note that the pressure accumulation control shown in this chapter is performed in the second REG mode.

(Brake fluid discharge controller 61)
The brake fluid discharge control unit 61 discharges the brake fluid accumulated in the accumulator 431 by the brake fluid discharge unit 6D when the vehicle speed VS detected by the vehicle speed sensor 76 is less than the predetermined speed VS0. The brake fluid discharge part 6D preferably includes a pressure increasing valve 42 and a pressure reducing valve 41. The pressure increasing valve 42 corresponds to a “first control valve”, and the pressure reducing valve 41 corresponds to a “second control valve”. In this case, the brake fluid accumulated in the accumulator 431 can be discharged to the reservoir 171 by opening the pressure increasing valve 42 and the pressure reducing valve 41.

  As shown in FIGS. 1 and 2, the brake fluid flows from the accumulator 431 to the piping 431a, the port 4a, the first chamber 4A, the port 4b, the piping 422, the pressure increasing valve 42, the piping 421, the port 4g, the pilot chamber 4D, and the port 4f. The pipe 413, the pressure reducing valve 41, the pipe 411, the pipe 161, and the port 11a are discharged to the reservoir 171. Thereby, the hydraulic pressure (accumulator pressure Pac) accumulated in the accumulator 431 can be reduced.

  In the present embodiment, when the vehicle speed VS is lower than the predetermined speed VS0, that is, when a relatively large braking force is not required (for example, during low-speed traveling or when stopped), the brake fluid accumulated in the accumulator 431 is used. The accumulator pressure Pac can be reduced by discharging. As a result, the accumulator pressure Pac necessary for braking can be secured, and the durability of the vehicle braking control device can be enhanced.

  Also, the brake fluid discharge control unit 61 can discharge the brake fluid of the accumulator 431 from the accumulator 431 to the reservoir 171 via the pilot chamber 4D of the regulator 44 by opening the pressure increasing valve 42 and the pressure reducing valve 41. it can. Thus, the booster valve 42 and the pressure reducing valve 41 that control the pilot pressure Pd can also be used as the brake fluid discharge part 6D, so that the cost of the vehicle brake control device can be reduced.

(Pump control unit 62)
The pump control unit 62 starts discharging brake fluid by the pump 432 when the accumulator pressure Pac becomes lower than a predetermined pump operation start hydraulic pressure. When the accumulator pressure Pac becomes equal to or higher than the predetermined pump operation stop hydraulic pressure, the pump 432 Stop the brake fluid discharge. Specifically, when the accumulator pressure Pac detected by the hydraulic pressure sensor 75 becomes less than a predetermined pump operation start hydraulic pressure, the motor 433 is driven, and the brake fluid stored in the reservoir 434 is transferred from the pump 432 to the accumulator 431. Supply. Thereby, pressure energy is replenished to the accumulator 431 and the accumulator pressure Pac increases.

  On the other hand, when the accumulator pressure Pac detected by the hydraulic pressure sensor 75 becomes equal to or higher than a predetermined pump operation stop hydraulic pressure, the driving of the motor 433 is stopped. As a result, the supply of the brake fluid from the pump 432 to the accumulator 431 is stopped, and the accumulator pressure Pac does not increase. That is, the accumulator pressure Pac can be set to a predetermined hydraulic pressure by driving or stopping the motor 433 by comparing the pump operation start hydraulic pressure and the pump operation stop hydraulic pressure with the accumulator pressure Pac.

  The pump operation start hydraulic pressure and the pump operation stop hydraulic pressure can be set according to the vehicle speed VS, for example. The pump operation start hydraulic pressure and the pump operation stop hydraulic pressure can be set to the accumulator pressure Pac that can generate the servo pressure Ps necessary at the vehicle speed VS. A plurality of pump operation start fluid pressures and pump operation stop fluid pressures can be set, and it is preferable to set the pump operation start fluid pressure and the pump operation stop fluid pressure according to the vehicle speed VS.

  For example, consider a case where the pump operation stop hydraulic pressure is set to a predetermined normal pressure accumulation end pressure PH1 and the pump operation start hydraulic pressure is set to a predetermined normal pressure accumulation start pressure PH2. In this case, the pump control unit 62 starts the discharge of brake fluid by the pump 432 when the accumulator pressure Pac becomes less than the normal pressure start pressure PH2, and the brake by the pump 432 when the accumulator pressure Pac becomes equal to or higher than the normal pressure end pressure PH1. Stop liquid discharge. Thereby, the accumulator pressure Pac can be maintained in the range from the normal pressure accumulation start pressure PH2 to the normal pressure accumulation end pressure PH1.

  Similarly, when the pump operation stop hydraulic pressure is set to a predetermined load reduction accumulation end pressure PL1 and the pump operation start hydraulic pressure is set to a predetermined load reduction accumulation start pressure PL2, the accumulator pressure Pac is set to the load reduction accumulation pressure. It can be maintained in a range from the start pressure PL2 to the load reduction pressure accumulation end pressure PL1. Here, it is assumed that the load reduction pressure accumulation end pressure PL1 is lower than the normal pressure accumulation end pressure PH1, and the load reduction pressure accumulation start pressure PL2 is lower than the normal pressure accumulation end pressure PH2. Further, the load reduction pressure accumulation end pressure PL1 is lower than the normal pressure accumulation start pressure PH2. The pump operation start hydraulic pressure and the pump operation stop hydraulic pressure can be derived in advance by simulation, measurement by an actual machine, and the like, and are stored in the memory.

(Pump working fluid pressure setting unit 63)
The pump operation hydraulic pressure setting unit 63 is configured so that when the vehicle speed VS detected by the vehicle speed sensor 76 is less than the predetermined speed VS0, the pump operation start hydraulic pressure and the pump operation stop are compared with the case where the vehicle speed VS is equal to or higher than the predetermined speed VS0. Set fluid pressure low. For example, when the vehicle speed VS is less than the predetermined speed VS0, the pump operation hydraulic pressure setting unit 63 sets the pump operation stop hydraulic pressure to the load reduction pressure accumulation end pressure PL1, and sets the pump operation start hydraulic pressure to the load reduction pressure accumulation start pressure. Set to PL2. Then, when the vehicle speed VS is equal to or higher than the predetermined speed VS0, the pump operation hydraulic pressure setting unit 63 sets the pump operation stop hydraulic pressure to the normal pressure accumulation end pressure PH1, and the pump operation start hydraulic pressure to the normal pressure accumulation start pressure PH2. Set. In this specification, the pressure accumulation control of the accumulator pressure Pac performed when the vehicle speed VS is equal to or higher than the predetermined speed VS0 is referred to as “normal pressure accumulation control”. On the other hand, the pressure accumulation control for accumulator pressure Pac performed when the vehicle speed VS is lower than the predetermined speed VS0, and the pressure accumulation control for reducing the load on the accumulator 431 is referred to as “accumulator load reduction pressure accumulation control”.

  In the present embodiment, when the vehicle speed VS is lower than the predetermined speed VS0, the pump operation start hydraulic pressure and the pump operation stop hydraulic pressure are set lower than when the vehicle speed VS is equal to or higher than the predetermined speed VS0. Therefore, the hydraulic pressure level of the accumulator 431 when a relatively large braking force is not required is lower than the pump operation starting hydraulic pressure (normal pressure accumulation starting pressure PH2) when a relatively large braking force is required. Pump operation stop hydraulic pressure (load reduction) that is higher than the hydraulic pressure (load reduction pressure accumulation start pressure PL2) and smaller than the pump operation stop hydraulic pressure (normal pressure accumulation end pressure PH1) when a relatively large braking force is required. The pressure is less than the pressure accumulation end pressure PL1). In short, the hydraulic pressure level of the accumulator 431 when a relatively large braking force is not required can be made lower than the hydraulic pressure level of the accumulator 431 when a relatively large braking force is required.

  Furthermore, in this embodiment, when the vehicle speed VS is less than the predetermined speed VS0, the brake fluid of the accumulator 431 is discharged. Therefore, when a relatively large braking force is not required, draining the brake fluid from the accumulator 431 can quickly reduce the hydraulic pressure level of the accumulator 431 and improve the durability of the vehicle brake control device.

  When the vehicle speed VS is less than the predetermined speed VS0, the brake fluid discharge control unit 61 accumulates pressure in the accumulator 431 by the brake fluid discharge unit 6D until the accumulator pressure Pac becomes lower than the pump operation stop hydraulic pressure. It is preferable to drain the brake fluid. In this case, the hydraulic pressure level of the accumulator 431 when a relatively large braking force is not required can be reduced more quickly.

  Here, if the brake fluid of the accumulator 431 is discharged until the accumulator pressure Pac becomes lower than the pump operation start hydraulic pressure, the pump 432 operates until the accumulator pressure Pac becomes equal to or higher than the pump operation stop hydraulic pressure. For this reason, it takes time for the accumulator pressure Pac to be lower than the pump operation stop hydraulic pressure and higher than the pump operation start hydraulic pressure.

  Therefore, when the vehicle speed VS is less than the predetermined speed VS0, the brake fluid discharge control unit 61 increases the brake fluid until the accumulator pressure Pac is less than the pump operation stop fluid pressure and equal to or higher than the pump operation start fluid pressure. It is preferable to discharge the brake fluid accumulated in the accumulator 431 by the discharge unit 6D. As a result, the hydraulic pressure level of the accumulator 431 when a relatively large braking force is not required can be reduced more rapidly.

  FIG. 5 is an explanatory diagram showing an example of a change with time of the accumulator pressure Pac. The horizontal axis represents time t, and the vertical axis represents accumulator pressure Pac. A curve L3 indicates accumulator load reduction pressure accumulation control, and a curve L4 indicates normal pressure accumulation control. The predetermined accumulator pressure PM0 shown in the figure is an accumulator pressure Pac that can generate the servo pressure Ps required when the vehicle speed VS is lower than the predetermined speed VS0. The load reduction pressure accumulation end pressure PL1 is set by subtracting the amount of pressure applied to the master chamber by the driver's pedal depression force Ft from the predetermined accumulator pressure PM0. The predetermined accumulator pressure PM0 can be derived in advance by simulation, measurement with an actual machine, etc., and is stored in the memory. It should be noted that the predetermined accumulator pressure PM0 can be matched with the load reduction pressure accumulation end pressure PL1.

  In the accumulator load reduction pressure accumulation control indicated by the curve L3, the pressure increasing valve 42 and the pressure reducing valve 41 are opened, the brake fluid accumulated in the accumulator 431 is discharged, and the accumulator pressure Pac is decreased. At this time, the brake fluid discharge control unit 61 opens the pressure increasing valve 42 and the pressure reducing valve 41 until the accumulator pressure Pac becomes a hydraulic pressure lower than the predetermined accumulator pressure PM0, and the brake fluid accumulated in the accumulator 431 is stored. Discharge. In the figure, the time when the pressure increasing valve 42 and the pressure reducing valve 41 are opened is indicated by t0, and the time when the pressure increasing valve 42 and the pressure reducing valve 41 are closed is indicated by t1.

  In the accumulator load reduction pressure accumulation control, the pump operation stop hydraulic pressure is set to the load reduction pressure accumulation end pressure PL1, and the pump operation start hydraulic pressure is set to the load reduction pressure accumulation start pressure PL2. Therefore, after time t1, the accumulator pressure Pac is maintained in a range from the load reduction pressure accumulation start pressure PL2 to the load reduction pressure accumulation end pressure PL1.

  On the other hand, in the normal pressure accumulation control indicated by the curve L4, the pressure increasing valve 42 and the pressure reducing valve 41 are not opened. Therefore, the accumulator pressure Pac is higher than in the case of accumulator load reduction pressure accumulation control. In the normal accumulation control, the pump operation stop hydraulic pressure is set to the normal accumulation end pressure PH1, and the pump operation start hydraulic pressure is set to the normal accumulation start pressure PH2. Therefore, the accumulator pressure Pac is maintained in the range from the normal pressure accumulation start pressure PH2 to the normal pressure accumulation end pressure PH1.

  FIG. 6 is a flowchart illustrating an example of a control procedure of the pressure accumulation control. The brake ECU 6 has a microcomputer including a CPU and a memory (not shown), and can execute pressure accumulation control of the accumulator 431 by executing a program stored in the memory. The pressure accumulation control of the accumulator 431 is repeatedly executed every elapse of a predetermined time.

  In step S101, the accumulator pressure Pac is detected. The accumulator pressure Pac is detected by a hydraulic pressure sensor 75. Next, in step S102, the open / close state of the control valve 22 and the control valve 3 is detected. If the control valve 22 is closed or the control valve 3 is open (Yes) in step S103, the process proceeds to step S104. When the condition is not satisfied (in the case of No), the process proceeds to step S301 and normal pressure accumulation control is performed.

  In step S104, the vehicle speed VS of the vehicle is detected. The vehicle speed VS is detected by a vehicle speed sensor 76. Next, in step S105, the vehicle speed VS is compared with a predetermined speed VS0. When the vehicle speed VS is less than the predetermined speed VS0 (in the case of Yes), the process proceeds to step S106, and accumulator load reduction pressure accumulation control is performed. When the vehicle speed VS is equal to or higher than the predetermined speed VS0 (in the case of No), the process proceeds to step S301, and normal pressure accumulation control is performed.

  In the accumulator load reduction pressure accumulation control, first, in step S106, the pump operation stop hydraulic pressure is set to the load reduction pressure accumulation end pressure PL1, and the pump operation start hydraulic pressure is set to the load reduction pressure accumulation start pressure PL2. When this routine is repeatedly processed, it is not necessary to set the pump operation stop hydraulic pressure and the pump operation start hydraulic pressure each time. Next, in step S107, the accumulator pressure Pac is compared with a predetermined accumulator pressure PM0. When the accumulator pressure Pac is greater than the predetermined accumulator pressure PM0 (in the case of Yes), the process proceeds to step S108.

  In step S108, the pressure increasing valve 42 and the pressure reducing valve 41 are opened until the accumulator pressure Pac becomes equal to or lower than the predetermined accumulator pressure PM0. When the accumulator pressure Pac becomes equal to or lower than the predetermined accumulator pressure PM0, the pressure increasing valve 42 and the pressure reducing valve 41 are once closed. Thereafter, similarly to the linear mode, the open / close states of the pressure increasing valve 42 and the pressure reducing valve 41 are appropriately controlled according to the required servo pressure Ps. Thereby, the desired servo pressure Ps can be generated in the servo chamber 1A. And this routine is once complete | finished.

  In step S107, when the accumulator pressure Pac is equal to or lower than the predetermined accumulator pressure PM0 (in the case of No), the process proceeds to step S201. In step S201, the accumulator pressure Pac is compared with the load reduction pressure accumulation end pressure PL1. When the accumulator pressure Pac is smaller than the load reduction pressure accumulation end pressure PL1 (in the case of Yes), the process proceeds to step S202. In step S202, the accumulator pressure Pac is compared with the load reduction pressure accumulation start pressure PL2. When the accumulator pressure Pac is smaller than the load reduction pressure accumulation start pressure PL2 (in the case of Yes), the process proceeds to step S203, and the drive of the motor 433 is started. As a result, the brake fluid stored in the reservoir 434 is supplied from the pump 432 to the accumulator 431, and pressure energy is supplied to the accumulator 431. Accordingly, the accumulator pressure Pac increases.

  In step S201, when the accumulator pressure Pac is equal to or higher than the load reduction accumulation pressure PL1 (in the case of No), the process proceeds to step S204, and the driving of the motor 433 is stopped. Thereby, the supply of the brake fluid from the pump 432 to the accumulator 431 is stopped. That is, the accumulator pressure Pac does not increase. In step S202, when the accumulator pressure Pac is equal to or higher than the load reduction pressure accumulation start pressure PL2 (in the case of No), this routine is temporarily ended. That is, when the accumulator pressure Pac is equal to or higher than the load reduction pressure accumulation start pressure PL2 and less than the load reduction pressure accumulation end pressure PL1, the motor 433 continues the previous state. That is, if the motor 433 was driven during the previous processing of this routine, the driving of the motor 433 is continued. On the other hand, if the motor 433 was stopped during the previous processing of this routine, the motor 433 is stopped.

  Next, normal pressure accumulation control will be described. In the normal pressure accumulation control, first, in step S301, the pump operation stop hydraulic pressure is set to the normal pressure accumulation end pressure PH1, and the pump operation start hydraulic pressure is set to the normal pressure accumulation start pressure PH2. When this routine is repeatedly processed, it is not necessary to set the pump operation stop hydraulic pressure and the pump operation start hydraulic pressure each time. Then, the process proceeds to step S302.

  In step S302, the accumulator pressure Pac is compared with the normal pressure accumulation end pressure PH1. When the accumulator pressure Pac is smaller than the normal pressure accumulation end pressure PH1 (in the case of Yes), the process proceeds to step S303. In step S303, the accumulator pressure Pac is compared with the normal pressure accumulation start pressure PH2. When the accumulator pressure Pac is smaller than the normal pressure accumulation start pressure PH2 (in the case of Yes), the process proceeds to step S304, and the drive of the motor 433 is started. Thereby, the accumulator pressure Pac increases.

  In step S302, when the accumulator pressure Pac is equal to or higher than the normal pressure accumulation end pressure PH1 (in the case of No), the process proceeds to step S305, and the driving of the motor 433 is stopped. Thereby, the accumulator pressure Pac does not increase. In step S303, when the accumulator pressure Pac is equal to or higher than the normal pressure accumulation start pressure PH2 (in the case of No), this routine is once ended. That is, when the accumulator pressure Pac is not less than the normal pressure accumulation start pressure PH2 and less than the normal pressure accumulation end pressure PH1, the motor 433 continues the previous state. That is, if the motor 433 was driven during the previous processing of this routine, the driving of the motor 433 is continued. On the other hand, if the motor 433 was stopped during the previous processing of this routine, the motor 433 is stopped.

  Step S101 is performed by the hydraulic pressure sensor 75. Step S104 is performed by the vehicle speed sensor 76. Steps S201 to S204 and S302 to S305 are performed by the pump control unit 62. Steps S106 and S301 are performed by the pump hydraulic pressure setting unit 63. Other than these, the brake fluid discharge control unit 61 performs.

  FIG. 7 is an explanatory diagram showing an example of changes over time of the drive current, the pedal stroke Fs, the pedal depression force Ft, the accumulator pressure Pac, the master pressure Pm, and the servo pressure Ps of the pressure increasing valve 42. The horizontal axis indicates time t. A curve L5 shows a change with time of the drive current of the pressure increasing valve 42, a curve L6 shows a change with time of the pedal stroke Fs, and a curve L7 shows a change with time of the pedal depression force Ft. A curve L8 indicates a change with time of the accumulator pressure Pac, a curve L9 indicates a change with time of the master pressure Pm, and a curve L10 indicates a change with time of the servo pressure Ps.

  It is assumed that the driver starts operating the brake pedal 10 at time t10 and continues the brake operation until time t14. Along with this, the pedal stroke Fs and the pedal effort Ft gradually increase and eventually become substantially constant. Then, the pedal stroke Fs and the pedal depression force Ft suddenly decrease as the operation of the brake pedal 10 ends (curves L6 and L7). As the pedal stroke Fs and the pedal effort Ft increase, the accumulator pressure Pac gradually decreases, and the master pressure Pm and servo pressure Ps gradually increase (curves L8 to L10).

  It is assumed that the pressure increasing valve 42 and the pressure reducing valve 41 are opened at time t11. At this time, a drive current for opening the pressure increasing valve 42 flows (curve L5). Then, the accumulator pressure Pac decreases and becomes substantially the same pressure as the servo pressure Ps at time t12. After time t12, the servo pressure Ps decreases following the decrease in the accumulator pressure Pac (curves L8 and L10). At this time, the master pressure Pm also decreases due to the decrease in the servo pressure Ps (curve L9).

  It is assumed that the pressure increasing valve 42 and the pressure reducing valve 41 are closed at time t13. At this time, there is no driving current for opening the pressure increasing valve 42 (curve L5). When the operation of the brake pedal 10 is completed at time t14, the master pressure Pm and the servo pressure Ps are not rapidly reduced (curves L9 and L10). It is assumed that vehicle speed VS is lower than predetermined speed VS0, and accumulator pressure Pac at time t13 is lower than predetermined accumulator pressure PM0.

  In the vehicle braking control device according to the present embodiment, it is conceivable that the master pressure Pm becomes high when the hydraulic pressure corresponding to the master pressure Pm is output from the regulator 44 to the servo chamber 1A. Specifically, when the first master piston 14 and the second master piston 15 move forward by the brake operation and the master pressure Pm increases, the servo pressure Ps increases due to the increase in the master pressure Pm. Therefore, if the brake operation force is not reduced, the first master piston 14 and the second master piston 15 further advance and the master pressure Pm increases. It is conceivable that the master pressure Pm is increased by repeating such an increase cycle of the master pressure Pm.

  On the other hand, in this embodiment, when the hydraulic pressure corresponding to the master pressure Pm is output to the servo chamber 1A by the regulator 44 and the vehicle speed VS is less than the predetermined speed VS0, the brake fluid of the accumulator 431 is obtained. Is discharged. Thereby, it can suppress that the master pressure Pm becomes high by repeating the increase cycle of the said master pressure Pm.

  Further, in the vehicle brake control device according to the present embodiment, when the separation chamber 1B is sealed, the brake fluid in the separation chamber 1B becomes a rigid body, so that the first master piston 14 and the second master piston 15 are input. It moves with the piston 13. In this case, since the operating force with respect to the brake pedal 10 acts on the first master piston 14 and the second master piston 15 as they are, it is conceivable that the master pressure Pm becomes high.

  On the other hand, in the present embodiment, the brake fluid in the accumulator 431 is discharged when the separation chamber 1B is in a sealed state and the vehicle speed VS is less than the predetermined speed VS0. Thereby, it can suppress that the master pressure Pm becomes high resulting from the separation chamber 1B being in a sealed state.

  Furthermore, in the vehicle brake control device according to the present embodiment, when the flow of the brake fluid from the reaction force chamber 1C to the reservoir 171 is allowed, the reaction force against the operation of the brake pedal 10 is reduced. It is conceivable that the pressure Pm becomes high.

  On the other hand, in this embodiment, when the control valve 3 allows the brake fluid to flow from the reaction force chamber 1C to the reservoir 171 and the vehicle speed VS is less than the predetermined speed VS, the accumulator 431 Drain the brake fluid. Thereby, it is possible to suppress the master pressure Pm from becoming high due to the fact that the flow of the brake fluid from the reaction force chamber 1C to the reservoir 171 is permitted.

(3) Others The present invention is not limited to the embodiment described above and shown in the drawings, and can be implemented with appropriate modifications within a range not departing from the gist. For example, the brake fluid discharge part 6 </ b> D can be provided with a control valve separately instead of the pressure increasing valve 42 and the pressure reducing valve 41. In this case, for example, the pipe can be branched from the middle of the pipe 431a and connected to the reservoir 171 via a control valve (not shown). As the control valve, for example, a normally closed electromagnetic valve can be used. By opening the control valve, the brake fluid accumulated in the accumulator 431 can be discharged to the reservoir 171. Thereby, for example, pressure accumulation control of the accumulator 431 can be performed when the pressure increasing valve 42 and the pressure reducing valve 41 fail, that is, in the first REG mode. Further, by using these together, it is possible to improve the reliability.

  When the ABS control is not performed, the ABS 53 can be omitted. Also, when performing ABS control, the configuration of the ABS 53 is not limited to the above. For example, an actuator (not shown) capable of further increasing / decreasing the master pressure Pm for the wheel cylinders 541 to 544 may be installed on the downstream side (wheel cylinders 541 to 544 side) of the holding valve 531. In this case, the actuator has, for example, a cylinder and a piston, and the drive of the piston can be controlled by the brake ECU 6. Further, a pedal force sensor may be provided instead of the stroke sensor 72. In this case, in the control of the brake ECU 6, the pedal effort of the brake pedal 10 can be used instead of the pedal stroke amount. These may be used in combination.

1: master cylinder, 10: brake pedal (brake operating member),
11: Main cylinder (housing),
13: Input piston,
14: First master piston (output piston),
15: Second master piston (output piston), 171: Reservoir,
1A: servo room, 1B: separation room, 1C: reaction force room,
1D: first hydraulic chamber (master chamber), 1E: second hydraulic chamber (master chamber),
2: reaction force generator, 22: control valve (separation chamber opening / closing part), 3: control valve,
4: Servo pressure generator,
41: Pressure reducing valve (second control valve, brake fluid discharge part 6D),
42: Booster valve (first control valve, brake fluid discharge part 6D),
431: Accumulator (pressure accumulator), 432: Pump,
44: Regulator (regulator), 4D: Pilot room,
5: Brake device
541, 542, 543, 544: wheel cylinders,
6: Brake ECU,
61: Brake fluid discharge control unit,
62: Pump control unit,
63: Pump hydraulic pressure setting unit,
75: Fluid pressure sensor (fluid pressure acquisition unit), 76: Vehicle speed sensor (vehicle speed acquisition unit)

Claims (7)

A vehicular braking control device that includes a pressure accumulating unit that accumulates brake fluid, and pressurizes a wheel cylinder of the vehicle using the hydraulic pressure of the accumulating unit,
A brake fluid discharger capable of discharging the brake fluid accumulated in the pressure accumulation unit;
A vehicle speed acquisition unit for acquiring the vehicle speed of the vehicle;
When the vehicle speed acquired by the vehicle speed acquisition unit is less than a predetermined speed, a brake fluid discharge control unit that discharges the brake fluid accumulated in the pressure storage unit by the brake fluid discharge unit;
A pump communicated with the pressure accumulator and capable of discharging the brake fluid to the pressure accumulator;
A hydraulic pressure acquisition unit that acquires the hydraulic pressure of the brake fluid accumulated in the pressure accumulation unit;
When the hydraulic pressure acquired by the hydraulic pressure acquisition unit becomes less than a predetermined pump operation start hydraulic pressure, the pump starts discharging the brake fluid, and the hydraulic pressure acquired by the hydraulic pressure acquisition unit is predetermined. A pump control unit that stops the discharge of the brake fluid by the pump when the pump operation stop hydraulic pressure is exceeded,
When the vehicle speed is less than the predetermined speed, a pump operation hydraulic pressure setting unit that sets the pump operation start hydraulic pressure and the pump operation stop hydraulic pressure lower than when the vehicle speed is equal to or higher than the predetermined speed;
A braking control device for a vehicle comprising: The brake fluid discharge control unit is accumulated in the pressure accumulation unit by the brake fluid discharge unit until the hydraulic pressure acquired by the hydraulic pressure acquisition unit becomes a hydraulic pressure lower than the pump operation stop hydraulic pressure. The braking control device for a vehicle according to claim 1, wherein the brake fluid is discharged . The brake fluid discharge control unit is accumulated in the pressure accumulation unit by the brake fluid discharge unit until the hydraulic pressure acquired by the hydraulic pressure acquisition unit is equal to or higher than the pump operation start hydraulic pressure . The braking control device for a vehicle according to claim 2, wherein the brake fluid is discharged. A vehicular braking control device that includes a pressure accumulating unit that accumulates brake fluid, and pressurizes a wheel cylinder of the vehicle using the hydraulic pressure of the accumulating unit,
A brake fluid discharger capable of discharging the brake fluid accumulated in the pressure accumulation unit;
A vehicle speed acquisition unit for acquiring the vehicle speed of the vehicle;
When the vehicle speed acquired by the vehicle speed acquisition unit is less than a predetermined speed, a brake fluid discharge control unit that discharges the brake fluid accumulated in the pressure storage unit by the brake fluid discharge unit;
A master cylinder configured such that an output piston is driven and moved by a servo pressure in a servo chamber, and a master pressure in the master chamber is changed by the movement of the output piston;
The hydraulic pressure of the brake fluid that is communicated with the pressure accumulating unit, the master chamber, and the servo chamber and is accumulated in the pressure accumulating unit is adjusted to a hydraulic pressure corresponding to the master pressure, and the adjusted hydraulic pressure is adjusted. A mechanical pressure regulator capable of outputting to the servo chamber,
The brake fluid discharge controller is accumulated in the accumulator when the servo pressure is regulated according to the master pressure by the pressure regulator and the vehicle speed is less than the predetermined speed. A braking control device for a vehicle for discharging the brake fluid . A vehicular braking control device that includes a pressure accumulating unit that accumulates brake fluid, and pressurizes a wheel cylinder of the vehicle using the hydraulic pressure of the accumulating unit,
A brake fluid discharger capable of discharging the brake fluid accumulated in the pressure accumulation unit;
A vehicle speed acquisition unit for acquiring the vehicle speed of the vehicle;
When the vehicle speed acquired by the vehicle speed acquisition unit is less than a predetermined speed, a brake fluid discharge control unit that discharges the brake fluid accumulated in the pressure storage unit by the brake fluid discharge unit;
A cylindrical housing closed at the front, an output piston disposed in the housing so that the master chamber is partitioned in front of itself, and a separation chamber is partitioned behind the output piston, A master cylinder having an input piston disposed behind the output piston in the housing and having a rear end connected to a brake operation member and moved by an operation force applied to the brake operation member;
A separation chamber opening and closing section that switches to an open state in which the brake fluid flows into and out of the separation chamber or a sealed state in which the brake fluid does not flow into and out of the separation chamber,
The brake fluid discharge control unit is configured to store the brake fluid accumulated in the pressure accumulation unit by the brake fluid discharge unit when the separation chamber is in the sealed state and the vehicle speed is less than the predetermined speed. Brake control device for vehicles to be discharged . A vehicular braking control device that includes a pressure accumulating unit that accumulates brake fluid, and pressurizes a wheel cylinder of the vehicle using the hydraulic pressure of the accumulating unit,
A brake fluid discharger capable of discharging the brake fluid accumulated in the pressure accumulation unit;
A vehicle speed acquisition unit for acquiring the vehicle speed of the vehicle;
When the vehicle speed acquired by the vehicle speed acquisition unit is less than a predetermined speed, a brake fluid discharge control unit that discharges the brake fluid accumulated in the pressure storage unit by the brake fluid discharge unit;
A master cylinder that forms a reaction force chamber that generates a reaction force pressure corresponding to a reaction force that opposes the operation of the brake operation member, and generates a master pressure according to the operation amount of the brake operation member;
A control valve that is provided between the reaction force chamber and the reservoir and controls the flow of the brake fluid from the reaction force chamber to the reservoir;
The brake fluid discharge control unit is configured to discharge the brake fluid when the flow of the brake fluid from the reaction force chamber to the reservoir is permitted by the control valve and the vehicle speed is less than the predetermined speed. A brake control device for a vehicle that discharges the brake fluid accumulated in the pressure accumulating unit by the unit. A vehicular braking control device that includes a pressure accumulating unit that accumulates brake fluid, and pressurizes a wheel cylinder of the vehicle using the hydraulic pressure of the accumulating unit,
A brake fluid discharger capable of discharging the brake fluid accumulated in the pressure accumulation unit;
A vehicle speed acquisition unit for acquiring the vehicle speed of the vehicle;
When the vehicle speed acquired by the vehicle speed acquisition unit is less than a predetermined speed, a brake fluid discharge control unit that discharges the brake fluid accumulated in the pressure storage unit by the brake fluid discharge unit;
A master cylinder configured such that an output piston is driven and moved by a servo pressure in a servo chamber, and a master pressure in the master chamber is changed by the movement of the output piston;
A mechanical regulator that communicates with the pressure accumulator and the servo chamber, regulates the fluid pressure of the brake fluid accumulated in the accumulator to a fluid pressure corresponding to the pilot pressure in the pilot chamber, and outputs the fluid pressure to the servo chamber. Pressure part,
A first control valve provided between the pressure accumulator and the pilot chamber and controlling the flow of the brake fluid from the pressure accumulator to the pilot chamber;
A second control valve that is provided between the pilot chamber and the reservoir and controls the flow of the brake fluid from the pilot chamber to the reservoir;
The brake fluid discharge unit includes the first control valve and the second control valve,
The brake fluid discharge control unit is a vehicle brake control device that opens the first control valve and the second control valve to discharge the brake fluid accumulated in the pressure accumulating unit to the reservoir .

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