JP2012153204A - Brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake control device capable of suppressing a pump operation frequency.SOLUTION: The brake control device includes: a gate-out valve 12 which is provided in a system P of two brake piping systems and which is disposed in a first brake circuit (pile lines 11 and 18) between a primary chamber 15a of a master cylinder M/C and a wheel cylinder W/C; a branch oil passage 16 which has a reflux oil passage section 17 branching off from a section between the primary chamber 15a and the gate-out valve 12 in the first brake circuit; a stroke simulator valve 27 that is provided in the reflux oil passage section 17; a reservoir 34 into which a brake fluid flows from the master cylinder M/C via the stroke simulator valve 27; and a pump 35 which sucks in the brake fluid via the reservoir 34 so as to discharge the brake fluid to the branch oil passage 16 from the reflux oil passage section 17.

Description

  The present invention relates to a brake control device.

  In Patent Document 1, when the brake pedal stroke is located between the stroke start position and a predetermined position, the regenerative efficiency is increased by limiting the friction braking force generated by the master cylinder pressure that rises according to the brake pedal stroke, It is described that the restriction of the friction braking force is released when the brake pedal stroke exceeds a predetermined position.

Japanese Patent No. 4415379

However, in the above prior art, when the brake pedal stroke has not reached the predetermined position in a situation where regenerative braking is impossible, the friction braking force is insufficient with respect to the driver's required braking force, and the pressure is increased by pump-up. Since the brake fluid has to be supplied to the wheel cylinder, there is a problem that the pump is frequently operated.
The objective of this invention is providing the brake control apparatus which can suppress the operating frequency of a pump.

  The brake control device of the present invention is provided in at least one of the two brake piping systems, and is disposed in a first brake circuit between the first fluid chamber of the tandem master cylinder and the wheel cylinder. Solenoid valve, a branch oil passage having a first brake circuit and a return oil passage portion branched from between the first liquid chamber and the first electromagnetic valve, and a control valve provided in the return oil passage portion And a reservoir into which the brake fluid from the tandem master cylinder flows via the control valve, and a pump that sucks the brake fluid through the reservoir and discharges the brake fluid from the reflux oil passage portion to the branch oil passage.

  According to the present invention, the operation frequency of the pump can be suppressed.

1 is a system configuration diagram showing a braking / driving system of a vehicle to which a brake control device of Example 1 is applied. It is a circuit block diagram of the brake control apparatus of Example 1. It is a figure which shows operation | movement of the hydraulic circuit at the time of wheel cylinder pressure increase by a normal brake. It is a time chart of a normal brake. It is a figure which shows operation | movement of the hydraulic circuit at the time of wheel cylinder pressure pressure reduction by a normal brake. It is a figure which shows operation | movement of the hydraulic circuit at the time of wheel cylinder pressure increase in regeneration cooperation control (when driver demand is constant and the brake fluid is stored in the reservoir 23). In regenerative cooperative control, it is a time chart when a driver performs brake operation in a middle vehicle speed range. It is a figure which shows operation | movement of the hydraulic circuit at the time of the wheel cylinder pressure increase in regeneration cooperation control (when driver demand is constant and the brake fluid is not stored in the reservoir 23). 7 is a time chart when a driver performs a braking operation in a low vehicle speed range in regenerative cooperative control (when the brake pedal is depressed after completion of switching from regenerative braking force to friction braking force). It is a figure which shows operation | movement of the hydraulic circuit at the time of wheel cylinder pressure holding | maintenance in regenerative cooperative control (driver request constant). It is a figure which shows operation | movement of the hydraulic circuit at the time of wheel cylinder pressure pressure reduction (driver request constant) in regenerative cooperative control. It is a figure which shows operation | movement of the hydraulic circuit at the time of the wheel cylinder pressure increase in regeneration cooperation control (when a driver request | requirement increase and the brake fluid is stored by the reservoir 23). In regenerative cooperative control, it is a time chart when a driver performs brake operation in a high-speed region. It is a figure which shows operation | movement of the hydraulic circuit at the time of the wheel cylinder pressure increase in regeneration cooperation control (when a driver request | requirement increase and the brake fluid is not stored in the reservoir 23). It is a figure which shows operation | movement of the hydraulic circuit at the time of wheel cylinder pressure holding | maintenance in regenerative cooperative control (driver request increase). It is a figure which shows operation | movement of the hydraulic circuit at the time of wheel cylinder pressure pressure reduction (driver request increase) in regeneration cooperative control. It is a time chart when regenerative braking is prohibited at the beginning of braking. It is a figure which shows operation | movement of the hydraulic circuit at the time of wheel cylinder pressure increase in regeneration cooperation control (when a driver request | requirement reduction | decrease and the brake fluid is stored by the reservoir 23). FIG. 6 is a time chart when the wheel cylinder pressure is increased in regenerative cooperative control (when the driver request decreases and brake fluid is stored in the reservoir 23). It is a figure which shows operation | movement of the hydraulic circuit at the time of wheel cylinder pressure increase in regenerative cooperative control (when a driver request | requirement reduction | decrease and the brake fluid is not stored in the reservoir 23). In regenerative cooperative control, it is a time chart when a driver performs a brake operation in a low vehicle speed range (when the brake pedal is stepped back before completion of switching from regenerative braking force to friction braking force). It is a figure which shows operation | movement of the hydraulic circuit at the time of the wheel cylinder pressure holding | maintenance in regenerative cooperative control (when a driver request | requirement reduction | decrease and the brake fluid is stored in the reservoir 23). It is a figure which shows operation | movement of the hydraulic circuit at the time of wheel cylinder pressure holding | maintenance in regenerative cooperative control (when a driver request | requirement reduction | decrease and the brake fluid is not stored in the reservoir 23). FIG. 6 is a time chart when the wheel cylinder pressure is maintained in regenerative cooperative control (when the driver request decreases and no brake fluid is stored in the reservoir 23). It is a figure which shows operation | movement of the hydraulic circuit at the time of wheel cylinder pressure pressure reduction in regenerative cooperative control. It is a circuit block diagram of the brake control apparatus of another Example.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the brake control apparatus of this invention is demonstrated based on the Example shown on drawing.
[Example 1]
The configuration will be described.
FIG. 1 is a system configuration diagram showing a braking / driving system of a vehicle to which the brake control device of the first embodiment is applied, and FIG. 2 is a circuit configuration diagram of the brake control device of the first embodiment.
[System configuration]
The hydraulic pressure control unit HU is based on the friction braking force command from the brake control unit BCU. The wheel cylinder W / C (FL) for the left front wheel (regenerative wheel) FL and the wheel cylinder for the right rear wheel (non-regenerative wheel) RR Increase / decrease or maintain the hydraulic pressure of wheel cylinder W / C (RR), wheel cylinder W / C (FR) for front right wheel (regenerative wheel), wheel cylinder W / C (RL) for left rear wheel (non-regenerative wheel) RL To do.
The motor generator MG is a three-phase AC motor, which is connected to the left and right front wheels FL, FR via the drive shafts DS (FL), DS (FR) and the differential gear DG, respectively, and based on commands from the motor control unit MCU. , Power running or regenerative operation, and apply driving force or regenerative braking force to the left and right front wheels FL, FR.
The inverter INV performs the power running operation of the motor generator MG by converting the DC power of the battery BATT into AC power based on a drive command from the motor control unit MCU and supplying the AC power to the motor generator MG. On the other hand, based on a regenerative command from the motor control unit MCU, the AC power generated by the motor generator MG is converted into DC power and the battery BATT is charged to regenerate the motor generator MG.

The motor control unit MCU outputs a drive command to the inverter INV based on the drive force command from the drive controller 1. Also, based on the regenerative braking force command from the brake control unit BCU, the regenerative command is output to the inverter INV.
The motor control unit MCU sends the state of output control of the driving force or regenerative braking force by the motor generator MG and the maximum regenerative braking force that can be generated at present to the brake control unit BCU and drive controller 1 via the communication line 2. send. Here, the “maximum regenerative braking force that can be generated” is calculated (estimated) by, for example, the battery SOC estimated from the inter-terminal voltage and current value of the battery BATT or the wheel speed sensors 3FL, 3FR, 3RL, 3RR. Calculated from vehicle body speed (vehicle speed). Further, when turning, the calculation is performed in consideration of the steering characteristic of the vehicle.
That is, at the time of full charge when the battery SOC is in the upper limit value or near the upper limit value, it is necessary to prevent overcharge from the viewpoint of battery protection. Further, when the vehicle speed decreases due to braking, the maximum regenerative braking force that can be generated by motor generator MG decreases. Furthermore, when regenerative braking is performed during high-speed traveling, the inverter INV becomes a high load, so the maximum regenerative braking force is limited even during high-speed traveling.

In addition, in the vehicle of the first embodiment, since the regenerative braking force is applied to the front wheels, if the regenerative braking force is excessive with respect to the friction braking force at the time of turning, that is, the braking force of the front wheels is too large with respect to the rear wheel, The steer characteristic of the vehicle is prone to understeer and the turning behavior is disturbed. For this reason, when the understeer tendency becomes strong, the maximum regenerative braking force is limited, and the front and rear wheel distribution of the braking force during turning is determined according to the vehicle specifications (for example, front: rear = 6: 4). ).
The motor generator MG, the inverter INV, the battery BATT, and the motor control unit MCU constitute a regenerative braking device that generates a regenerative braking force for the wheels (left and right front wheels FL, FR).
Drive controller 1 inputs vehicle speed (vehicle speed) calculated by wheel speed sensors 3FL, 3FR, 3RL, 3RR, accelerator opening from accelerator opening sensor 4, battery SOC, etc. directly or via communication line 2 Is done.
The drive controller 1 performs operation control of the motor generator MG by a driving force command to the motor control unit MCU based on information from each sensor.

The brake control unit BCU is connected directly or through the communication line 2 to the master cylinder pressure from the master cylinder pressure sensor 5, the brake pedal stroke amount from the brake pedal stroke sensor 6, the steering wheel angle from the steering angle sensor 7, the wheel speed. The wheel speeds from the sensors 3FL, 3FR, 3RL, 3RR, the yaw rate from the yaw rate sensor 8, the battery SOC, and the like are input.
The brake control unit BCU calculates the braking force (all wheels) required for the vehicle based on the information from each sensor, etc., and distributes the necessary braking force between the regenerative braking force and the friction braking force, Operation control of the hydraulic pressure control unit HU by the friction braking force command to the control unit BCU and operation control of the motor generator MG by the regenerative braking force command to the motor control unit MCU are performed.
Here, in the first embodiment, as the regenerative cooperative control, the regenerative braking force is given priority over the friction braking force, and the maximum (maximum regenerative control) is used without using the hydraulic pressure as long as the necessary braking force can be covered by the regenerative component. The area of regeneration is expanded to (power). Thereby, especially in a traveling pattern in which acceleration / deceleration is repeated, energy recovery efficiency is high, and energy recovery by regenerative braking is realized up to a lower vehicle speed. The brake control unit BCU reduces the regenerative braking force when the regenerative braking is limited due to a decrease or increase in the vehicle speed, etc., and increases the friction braking force by that amount. Ensure the necessary braking force. Hereinafter, reducing the regenerative braking force to increase the friction braking force is referred to as switching from the regenerative braking force to the friction braking force, and conversely reducing the friction braking force to increase the regenerative braking force. This is called switching from power to regenerative braking force.

The brake control unit BCU directly increases the pressure using the hydraulic pressure generated by the driver's brake operation (normal braking), and controls to increase / decrease or maintain the wheel cylinder pressure using the discharge pressure of the pump P. With this wheel cylinder pressure control, automatic braking control, which automatically increases and decreases the wheel cylinder pressure based on the braking force required for various vehicle controls, including anti-lock brake control (hereinafter referred to as ABS control), is executed. Is possible.
Here, the ABS control means that when it is detected that a wheel tends to be locked during a driver's braking operation, the wheel cylinder pressure is reduced or reduced in order to generate the maximum braking force while preventing the wheel from being locked. This control repeats holding and increasing pressure. In addition, in the above automatic braking control, when it is detected that an oversteer tendency or an understeer tendency has become strong at the time of turning of the vehicle, a vehicle behavior stability control for stabilizing the vehicle behavior by controlling the wheel cylinder pressure of a predetermined wheel to be controlled. In addition, the brake assist control that generates higher pressure in the wheel cylinder W / C than the pressure that is actually generated in the master cylinder M / C when the driver operates the brake, and auto-cruise automatically depending on the relative relationship with the preceding vehicle Control for generating a braking force automatically. The brake control unit BCU includes an anti-lock brake control unit that performs ABS control and a vehicle behavior stabilization control unit that performs vehicle behavior stabilization control.

[Brake circuit configuration]
The hydraulic control unit HU according to the first embodiment has a piping structure called X piping that includes two systems of a P system and an S system. In addition, P and S attached to the end of the code | symbol of each site | part described in FIG. 2 show P system and S system, and RL, FR, FL, and RR are left rear wheel, right front wheel, left front wheel, and right rear. Indicates that it corresponds to a ring. In the following description, the description of P, S or RL, FR, FL, RR is omitted when the P, S system or each wheel is not distinguished.
The hydraulic control unit HU according to the first embodiment uses a closed hydraulic circuit. Here, the closed hydraulic circuit is a hydraulic circuit that returns the brake fluid supplied to the wheel cylinder W / C to the reservoir tank RSV via the master cylinder M / C.
The brake pedal BP is connected to the master cylinder M / C via the input rod IR. The input rod IR is provided with a negative pressure booster (booster) NPB that boosts the input of the input rod IR by negative pressure.
The master cylinder M / C is a tandem master cylinder, and has a primary piston 15c and a secondary piston 15d constituting a primary chamber (first liquid chamber) 15a and a secondary chamber 15b, and both pistons 15c and 15d are springs 15e. When the brake pedal BP is not depressed, the pistons 15c and 15d are pressed to return the brake pedal BP to the initial position side. The primary chamber 15a is connected to the P system of the hydraulic pressure control unit HU, and the secondary chamber 15b is connected to the S system.
The reservoir tank RSV is connected to each of the primary chamber and the secondary chamber via pipes (not shown) when the brake pedal BP is in the initial position. The reservoir tank RSV is connected to the master cylinder M / C according to the stroke of the input rod IR. The brake fluid is supplied to or the surplus brake fluid in the master cylinder M / C is stored.

Wheel P / W (C) for front right wheel FR and wheel cylinder W / C (RL) for rear left wheel RL are connected to P system, while wheel cylinder W / C (wheel front / left wheel cylinder W / C (RL) is connected to system S. FL), the wheel cylinder W / C (RR) of the right rear wheel RR is connected. The P system and S system are provided with a pump (second pump) PP and a pump (second pump) PS. The pump PP and the pump PS are, for example, gear pumps, driven by one motor M1, pressurizing the brake fluid sucked from the suction part 10a, and discharging it to the discharge part 10b.
The master cylinder M / C and the discharge part 10b of the pump P are connected by a pipe line 11 and a pipe line 31. The pipe 11 is provided with a gate-out valve (first electromagnetic valve) 12 which is a normally open type (fully opened when not energized and operates in the closing direction when energized) proportional solenoid valve. A pipe line 32 that bypasses the gate-out valve 12 is provided in the pipe line 11. A check valve 13 is provided on the pipe line 32. The check valve 13 allows the flow of brake fluid from the master cylinder M / C to the wheel cylinder W / C and prohibits the flow in the opposite direction.
A check valve 20 is provided on the pipe line 31. The check valve 20 allows the flow of brake fluid in the direction from the pump P toward the pipe 11 and prohibits the flow in the opposite direction.

The discharge part 10b of the pump P and the wheel cylinder W / C are connected by a pipe line 18. A solenoid-in valve (second electromagnetic valve) 19 which is a normally open proportional electromagnetic valve corresponding to each wheel cylinder W / C is provided on the pipe line 18.
On the pipeline 18, a pipeline 21 that bypasses the solenoid-in valve 19 is provided, and a check valve 22 is provided on the pipeline 21. This check valve 22 allows the flow of brake fluid in the direction from the wheel cylinder W / C toward the pump P, and prohibits the flow in the opposite direction. The pipeline 18 is connected at the connection point between the pipeline 11 and the pipeline 31.
The first brake that connects the master cylinder M / C that generates the brake fluid pressure by the driver's brake operation and the wheel cylinder W / C that is configured so that the brake fluid pressure acts by the pipeline 11 and the pipeline 18. A circuit is constructed.
The wheel cylinder W / C and the reservoir (second reservoir) 23 are connected by a conduit 24. The conduit 24 is provided with a solenoid-out valve 25 which is a normally closed solenoid valve (fully closed when not energized and operates in the opening direction when energized). The reservoirs 23P and 23S can store more than the amount of brake fluid corresponding to the maximum regenerative braking force limit value of the corresponding left and right front wheels FL and FR (the upper limit of the maximum regenerative braking force determined by the characteristics of the motor generator MG).
The master cylinder M / C and the reservoir 23 are connected by a pipeline 26. The reservoir 23 and the suction part 10a of the pump P are connected by a pipe 30.
Pipe lines 26, 30, and 31 branch from between the branch point of branch oil path 16 and one side of gate-out valve 12, and are connected to the first brake circuit (pipe 11) on the other side of gate-out valve 12. A second brake circuit.

The reservoir 23 includes a piston 23a and a gas spring (spring member) 23b that urges the piston 23a. The reservoir 23 also includes a pressure-sensitive check valve (regulating valve) 28 on the pipe line 26. The check valve 28 includes a seat portion 28a formed at the inlet 23c of the reservoir 23 and a valve body 28b that contacts the seat portion 28a. The valve body 28b is provided integrally with the piston 23a. When a predetermined amount of brake fluid is stored, or when the pressure in the pipe line 26 exceeds a predetermined pressure, the check valve 28 is seated on the seat portion 28a and closed, By prohibiting the inflow of the brake fluid into the reservoir 23, high pressure is prevented from being applied to the suction portion 10a of the pump P. The check valve 28 is opened when the pump P is activated and the pressure in the pipe line 30 becomes low, regardless of the pressure in the pipe line 26, the valve element 28b is separated from the seat portion 28a. The brake fluid is allowed to flow into the reservoir 23.
A branch oil passage 16 that branches from between the primary chamber 15a of the master cylinder M / C and the gate-out valve 12P is provided in the pipeline 11P of the P system. The branch oil passage 16 has a reflux oil passage portion 17 having both ends connected to the branch oil passage 16.
The reflux oil passage 17 is provided with a stroke simulator valve (control valve) 27, a reservoir 34, a pump (first pump) 35, and a check valve 36. The stroke simulator valve 27 is a normally closed proportional solenoid valve. The brake fluid from the master cylinder M / C flows into the reservoir 34 via the stroke simulator valve 27. The reservoir 34 can store more than the amount of brake fluid corresponding to the maximum regenerative braking force limit value (upper limit of the maximum regenerative braking force determined by the characteristics of the motor generator MG) of the left and right front wheels FL, FR. The pump 35 is, for example, a gear pump, and is driven by the motor M2. The pump 35 pressurizes the brake fluid sucked from the suction part 35a and discharges it to the discharge part 35b. As a result, the brake fluid stored in the reservoir 34 is discharged from the reflux oil passage portion 17 to the branch oil passage 16. The check valve 36 allows the flow of brake fluid from the pump 35 toward the branch oil passage 16 and prohibits the flow in the opposite direction.
The brake control unit BCU activates the valves 12, 19, 25, 27 and the motors M1, M2 according to the regenerative state of the regenerative braking device (motor generator MG, inverter INV, battery BATT) to reduce the brake fluid pressure. Control.

Hereinafter, the operation and action of each valve and each pump of the hydraulic pressure control unit HU in each scene of regenerative cooperative control will be described using a hydraulic circuit and a time chart. On the hydraulic circuit, the flow of brake fluid is indicated by a bold line. Also, on the time chart, “the braking force required for the vehicle determined from the brake pedal stroke” is “driver request”, “regenerative braking force” is “regenerative”, and “regenerative wheel friction braking force is“ friction (regenerative wheel) ” ”,“ Master cylinder pressure ”is“ MC pressure ”,“ Non-regenerative wheel RL, RR wheel cylinder pressure ”is“ WC pressure (non-regenerative wheel) ”, Regenerative wheel“ left and right front wheel FL, "FR wheel cylinder pressure" is "WC (regenerative wheel)", the amount of brake fluid stored in reservoir 34 is "for stroke absorption", the amount of brake fluid stored in reservoir 23 is "for decompression", stroke simulator valve 27 Is denoted as “SS”, the solenoid-in valve 19 as “S-in”, and the solenoid-out valve 25 as “S-out”.
[Normal brake]
(Foil cylinder pressure increase)
When the wheel cylinder pressure is increased by the normal brake, as shown in Fig. 3, all the valves and pumps are uncontrolled. From the master cylinder M / C to the wheel cylinder W / C only with the boost of the negative pressure booster NPB Brake fluid is sent to increase the wheel cylinder pressure (period from time t1 to time t2 in FIG. 4).
(Wheel cylinder pressure retention)
When the wheel cylinder pressure is maintained by the normal brake, the wheel cylinder pressure is maintained only by the boost of the negative pressure booster NPB (period from time t2 to time t3 in FIG. 4). There is no brake fluid flow on the hydraulic circuit. Therefore, the hydraulic circuit is in the state shown in FIG.
(Foil cylinder pressure reduction)
When the wheel cylinder pressure is reduced by the normal brake, as shown in Fig. 5, each valve and each pump are all uncontrolled, and only the boost of the negative pressure booster NPB is used to brake the wheel cylinder W / C to the master cylinder M / C. The liquid is returned and the wheel cylinder pressure is reduced (period from time t3 to time t4 in FIG. 4).

[Regenerative cooperative control]
(Driver requirement constant, regenerative wheel pressure increase)
In the regenerative braking control, when the driver request is constant and the wheel cylinder pressure is increased by reducing the regenerative braking force and the brake fluid is stored in the reservoir 23, as shown in FIG. Then, brake fluid is sent from the reservoir 34 to the regenerative wheels of the two brake systems via the master cylinder M / C to increase the wheel cylinder pressure of the regenerative wheels. More specifically, the discharge pressure of the pump 35 is sent to the P-type wheel cylinders W / C (FR) and W / C (RL) and simultaneously to the primary chamber 15a of the master cylinder M / C. In response to this, the secondary piston 15d moves to the right side in the figure and the secondary chamber 15b becomes narrow, so that the brake fluid is supplied to the S system accordingly. In other words, the same amount of brake fluid sent to the P system wheel cylinders W / C (FR), W / C (RL) is supplied to the S system wheel cylinders W / C (FL), W / C (RR ).
Further, the brake fluid is sent from the reservoir 23 to the two regenerative wheels of the brake by the pump P, and the wheel cylinder pressure of the regenerative wheel is increased. At this time, the pressure increase amount of the regenerative wheel is adjusted by proportionally controlling the solenoid-in valves 19FL and 19FR. In addition, the stroke simulator valve 27 leaks the excess discharge amount of the pump 35 and the pump P, and adjusts the brake pedal stroke and the master cylinder pressure to be equivalent to the driver request (relationship between the brake pedal stroke and the master cylinder pressure in the normal brake) ( (Period from time t5 to t6 in FIG. 7).
On the other hand, when the brake fluid is not stored in the reservoir 23, as shown in FIG. 8, the pump 35 sends the brake fluid from the reservoir 34 to the regenerative wheels of the two brake systems via the master cylinder M / C. Increase cylinder pressure. At this time, the pressure increase amount of the regenerative wheel is adjusted by proportionally controlling the solenoid-in valves 19FL and 19FR. Further, the surplus discharge amount of the pump 35 is leaked by the stroke simulator valve 27 (period from time t3 to time t4 in FIG. 9).
(Driver requirement constant, regenerative wheel holding)
In the regenerative cooperative control, when the driver request and the regenerative braking force are both constant and the wheel cylinder pressure is maintained, the brake fluid in the reservoir 34 is recirculated by the pump 35 and the stroke simulator valve 27 as shown in FIG. It circulates in the oil passage part 17 and is prepared so that it can respond to a driver demand increase / decrease immediately. Further, the solenoid-in valves 19FL and 19FR are closed to shut off the master cylinder M / C and the wheel cylinder W / C, and the brake fluid pressure of the regenerative wheel is maintained (period from time t2 to t3 in FIG. 9).
(Driver requirement constant, regenerative wheel decompression)
In the regenerative cooperative control, when the driver request is constant and the wheel cylinder pressure is reduced by increasing the regenerative braking force, the brake fluid in the reservoir 34 is recirculated by the pump 35 and the stroke simulator valve 27 as shown in FIG. It circulates in the oil passage part 17 and is prepared so that it can respond to a driver demand increase / decrease immediately. Further, the solenoid in valves 19FL and 19FR are closed to shut off the master cylinder M / C and the wheel cylinder W / C, and the solenoid out valves 25FL and 25FR are opened to reduce the pressure of the regenerative wheel (time t3 in FIG. 7). To t4).

(Increased driver demand, increased regeneration wheel pressure)
In the regenerative cooperative control, when the driver demand increases and the wheel cylinder pressure is increased and the brake fluid is stored in the reservoir 23, the non-regenerative wheel is equal to the driver demand pressure as shown in FIG. The regenerative wheel is adjusted by proportionally controlling the solenoid-in valves 19FL and 19FR. Further, the brake fluid is sent from the reservoir 23 to the two regenerative wheels of the brake by the pump P, and the wheel cylinder pressure of the regenerative wheel is increased. At this time, the brake pedal stroke and the master cylinder pressure are adjusted corresponding to the driver request by the stroke simulator valve 27 and the pump 35 (period from time t4 to time t5 in FIG. 13).
On the other hand, when the brake fluid is not stored in the reservoir 23, as shown in FIG. 14, the non-regenerative wheel is increased by the same pressure as the driver required pressure, and the regenerative wheel is adjusted by proportionally controlling the solenoid-in valves 19FL and 19FR. To do. At this time, the brake pedal stroke and the master cylinder pressure are adjusted corresponding to the driver request by the stroke simulator valve 27 and the pump 35 (period from time t2 to time t3 in FIG. 13).
(Driver demand increase, regenerative wheel retention)
In the regenerative cooperative control, when the wheel cylinder pressure is maintained when the driver demand increases, the non-regenerative wheel increases at the same pressure as the driver demand pressure as shown in FIG. The valves 19FL and 19FR are closed to shut off the master cylinder M / C and the wheel cylinder W / C to maintain the brake fluid pressure of the regenerative wheel. At this time, the brake pedal stroke and the master cylinder pressure are adjusted corresponding to the driver request by the stroke simulator valve 27 and the pump 35 (period from time t1 to time t2 in FIG. 13).
(Driver demand increase, regenerative wheel decompression)
In the regenerative cooperative control, when reducing the wheel cylinder pressure when the driver request and the regenerative braking force are both increased, as shown in FIG. 16, the non-regenerative wheel is increased at the same pressure as the driver required pressure, Solenoid in valves 19FL and 19FR are closed to shut off master cylinder M / C and wheel cylinder W / C, and solenoid out valves 25FL and 25FR are opened to reduce the pressure of the regenerative wheel. At this time, the brake pedal stroke and the master cylinder pressure are adjusted corresponding to the driver request by the stroke simulator valve 27 and the pump 35 (period from time t2 to time t3 in FIG. 17).

(Reduced driver requirements, increased regeneration wheel pressure)
In the regenerative cooperative control, when the driver demand decreases and the wheel cylinder pressure is increased and the brake fluid is stored in the reservoir 23, the non-regenerative wheel is equal to the driver demand pressure as shown in FIG. Depressurize with pressure. Further, the brake fluid is sent from the reservoir 23 to the two regenerative wheels of the brake by the pump P, and the wheel cylinder pressure of the regenerative wheel is increased. At this time, the pressure increase amount of the regenerative wheel is adjusted by proportionally controlling the solenoid-in valves 19FL and 19FR. Further, the brake pedal stroke and the master cylinder pressure are adjusted corresponding to the driver request by the stroke simulator valve 27 and the pump 35 (period from time t1 to time t2 in FIG. 19).
On the other hand, when no brake fluid is stored in the reservoir 23, as shown in FIG. 20, the non-regenerative wheel is depressurized at the same pressure as the driver required pressure. At this time, the pressure increase amount of the regenerative wheel is adjusted by proportionally controlling the solenoid-in valves 19FL and 19FR. Further, the brake pedal stroke and the master cylinder pressure are adjusted corresponding to the driver request by the stroke simulator valve 27 and the pump 35 (period from time t4 to time t5 in FIG. 21).
(Driver demand reduced, regenerative wheel retention)
In the regenerative cooperative control, when the driver demand is reduced and the wheel cylinder pressure is maintained and the brake fluid is stored in the reservoir 23, the non-regenerative wheel is equal to the driver demand pressure as shown in FIG. The pressure is reduced by the pressure, and the brake fluid is sent from the reservoir 23 to the master cylinder M / C by the pump P. Further, the solenoid in valves 19FL and 19FR are closed to shut off the master cylinder M / C and the wheel cylinder W / C, and the hydraulic pressure of the regenerative wheel is maintained. Further, the surplus discharge amounts of the pump 35 and the pump P are leaked by the stroke simulator valve 27, and the brake pedal stroke and the master cylinder pressure are adjusted to correspond to the driver request by the stroke simulator valve 27 and the pump 35 (from time t7 to t8 in FIG. 13). Period).
On the other hand, when the brake fluid is not stored in the reservoir 23, as shown in FIG. 23, the non-regenerative wheel is depressurized at the same pressure as the driver required pressure. Further, the solenoid in valves 19FL and 19FR are closed to shut off the master cylinder M / C and the wheel cylinder W / C, and the hydraulic pressure of the regenerative wheel is maintained. Further, the brake pedal stroke and the master cylinder pressure are adjusted corresponding to the driver request by the stroke simulator valve 27 and the pump 35 (period from time t1 to time t2 in FIG. 24).
(Reduced driver requirements, reduced regeneration wheel)
In the regenerative cooperative control, when the driver demand decreases and the wheel cylinder pressure is reduced, the non-regenerative wheel is reduced at the same pressure as the driver required pressure as shown in FIG. Send brake fluid to M / C. Further, the solenoid-in valves 19FL and 19FR are closed to shut off the master cylinder M / C and the wheel cylinder W / C, and the solenoid-out valves 25FL and 25FR are opened to reduce the hydraulic pressure of the regenerative wheel. At this time, the surplus discharge amounts of the pump 35 and the pump P are leaked by the stroke simulator valve 27, and the brake pedal stroke and the master cylinder pressure are adjusted to correspond to the driver request by the stroke simulator valve 27 and the pump 35 (from time t6 in FIG. 13). period until t7).

[Regenerative cooperative control at low vehicle speeds]
FIG. 9 is a time chart when the driver performs a braking operation in the low vehicle speed range in the regenerative cooperative control (when the brake pedal is stepped back after completion of switching from the regenerative braking force to the friction braking force).
At time t1, the driver has started depressing the brake pedal BP. Therefore, during the period from time t1 to time t2, the hydraulic circuit is in the state shown in FIG. 15, and the regenerative braking force rises as the driver demand increases. By maintaining the braking force, an increase in the friction braking force can be suppressed and the regeneration efficiency can be increased.
At time t2, the driver stops depressing the brake pedal BP and the brake pedal stroke becomes constant. Therefore, during the period from time t2 to t3, the hydraulic circuit is set to the state shown in FIG. 10 and the braking force is maintained constant.
At time t3, the regenerative braking force starts to decrease as the maximum regenerative braking force decreases due to deceleration. Therefore, during the period from time t3 to t4, the hydraulic circuit is in the state shown in FIG. By raising the braking force, the regenerative braking force is switched to the friction braking force.
At time t4, since the switching from the regenerative braking force to the friction braking force is completed, the hydraulic circuit is in the state shown in FIG. 2, the stroke simulator valve 27, the solenoid-in valve 19, and the pump 35 are not controlled, and the normal braking is performed. Therefore, during the period from time t4 to t5, the wheel cylinder pressure is held only by the boost of the negative pressure booster NPB.
At time t5, the driver has started to depress the brake pedal BP. Therefore, during the period from time t5 to time t6, the hydraulic circuit is in the state shown in FIG. Return brake fluid to cylinder M / C and reduce wheel cylinder pressure.
FIG. 21 is a time chart when the driver performs a braking operation in the low vehicle speed range in the regenerative cooperative control (when the brake pedal is stepped back before completion of switching from the regenerative braking force to the friction braking force).
The period from time t1 to t3 is the same as that in FIG.
At time point t3, the regenerative braking force starts to decrease as the maximum regenerative braking force decreases due to deceleration. Therefore, during the period from time point t3 to t4, the hydraulic circuit is in the state shown in FIG. 8 and friction is applied as the regenerative braking force decreases. By raising the braking force, the regenerative braking force is switched to the friction braking force.
At time t4, since the driver has started to depress the brake pedal BP, during the period from time t4 to t5, the hydraulic circuit is in the state shown in FIG. 20, and the switching from the regenerative braking force to the friction braking force is continued.
At time t5, since the switching from the regenerative braking force to the friction braking force is completed, the hydraulic circuit is brought into the state shown in FIG. 5, the stroke simulator valve 27, the solenoid-in valve 19, and the pump 35 are not controlled, and the normal braking is performed. Therefore, in the period from time t5 to t6, the brake fluid is returned from the wheel cylinder W / C to the master cylinder M / C only by the boost of the negative pressure booster NPB, and the wheel cylinder pressure is reduced.

[Regenerative cooperative control in the middle vehicle speed range]
FIG. 7 is a time chart when the driver performs a braking operation in the middle vehicle speed range in the regenerative cooperative control.
The period up to time t2 is the same as that in FIG.
Since the regenerative braking force has reached the maximum regenerative braking force at time t2, during the period from time t2 to t3, the hydraulic circuit is brought into the state shown in FIG. 14, and the friction braking force is raised according to the increasing driver demand and the regenerative braking force. .
At time t3, the driver stops depressing the brake pedal BP, and the brake pedal stroke becomes constant. Therefore, during the period from time t3 to time t4, the hydraulic circuit is set to the state shown in FIG. 11 according to the increasing regenerative braking force. Reduce friction braking force.
Since the regenerative braking force reaches the maximum braking force at time t4, the hydraulic circuit is brought into the state shown in FIG. 10 during the period from time t4 to t5, and the braking force is maintained.
At time t5, the regenerative braking force starts to decrease as the maximum regenerative braking force decreases due to deceleration. Therefore, during the period from time t5 to t6, the hydraulic circuit is in the state shown in FIG. Raise the braking force.
The period from time t6 to t8 is the same as the period from time t4 to t6 in FIG.
[Regenerative cooperative control at high vehicle speeds]
FIG. 13 is a time chart when the driver performs a brake operation in a high speed range in the regenerative cooperative control.
The period up to time t4 is the same as in FIG.
At time t4, the driver has started to depress the brake pedal BP. Therefore, during the period from time t4 to time t5, the hydraulic circuit is in the state shown in FIG. 12, and the friction braking force is increased according to the increasing driver demand and regenerative braking force. increase.
At time t5, the driver stops increasing the brake pedal BP and the brake pedal stroke becomes constant. Therefore, during the period from time t5 to t6, the hydraulic circuit is in the state shown in FIG. To reduce the friction braking force.
At time t6, since the driver has started to depress the brake pedal BP, during the period from time t6 to t7, the hydraulic circuit is brought into the state shown in FIG. 25, and friction control is performed according to the decreasing driver demand and the increasing regenerative braking force. Reduce power.
At time t7, the friction braking force of the regenerative wheel becomes zero. Therefore, during the period from time t7 to t8, the hydraulic circuit is set in the state shown in FIG. 22 and the friction braking force of the regenerative wheel is maintained at zero while the non-regenerative wheel is maintained. The friction braking force is reduced according to the driver's request.

[When regenerative braking is prohibited]
FIG. 4 is a time chart of normal braking.
At time t1, since the driver has started to depress the brake pedal BP, during the period from time t1 to time t2, the hydraulic circuit is in the state shown in FIG. 3, and the wheel cylinder pressure is increased only by the boost of the negative pressure booster NPB.
At time t2, the driver stopped increasing the brake pedal BP and the brake pedal stroke became constant, so the hydraulic circuit was in the state shown in Fig. 2. During the period from time t2 to t3, the booster of the negative pressure booster NPB Only hold the wheel cylinder pressure.
At time t3, since the driver has started to depress the brake pedal BP, during the period from time t3 to t4, the hydraulic circuit is brought into the state shown in FIG. 5, and the wheel cylinder pressure is reduced only by the boost of the negative pressure booster.
[When regenerative braking is prohibited at the beginning of braking]
FIG. 17 is a time chart in the case where regenerative braking is prohibited in the early stage of braking.
At time t1, the driver started to increase the brake pedal BP, but since regenerative braking is prohibited, during the period from time t1 to t2, the hydraulic circuit is in the state shown in FIG. Launch.
Since regenerative braking starts to rise at time t2, during the period from time t2 to t3, the hydraulic circuit is brought into the state shown in FIG. 16, and the friction braking force is reduced as the regenerative braking force increases.
At time t3, the driver stops increasing the brake pedal BP and the brake pedal stroke becomes constant. Therefore, during the period from time t3 to time t4, the hydraulic circuit is set to the state shown in FIG. 11 in accordance with the increasing regenerative braking force. To reduce the friction braking force.
At time t4, since the regenerative braking force reaches the maximum regenerative braking force, the hydraulic circuit is brought into the state shown in FIG. 10 during the period from time t4 to t5, and the braking force is maintained.
At time t5, the regenerative braking force starts to decrease as the maximum regenerative braking force decreases due to deceleration. Therefore, during the period from time t5 to t6, the hydraulic circuit is in the state shown in FIG. Raise the braking force.
At time t6, since the switching from the regenerative braking force to the friction braking force is completed, the hydraulic circuit is shifted to the normal brake with the state shown in FIG. Therefore, during the period from time t6 to t7, the wheel cylinder pressure is held only by the boost of the negative pressure booster NPB.
At time t7, since the driver has started to depress the brake pedal BP, during the period from time t7 to t8, the hydraulic circuit is brought into the state shown in FIG. 5, and the wheel cylinder pressure is reduced only by the boost of the negative pressure booster NPB.

As described above, in the brake control device according to the first embodiment, the branch oil passage 16 that branches from the position between the master cylinder M / C of the pipeline 11P of the P system and the gate-out valve 12P is provided. A reflux oil passage 17 having a stroke simulator valve 27, a reservoir 34, and a pump 35 is provided in the passage 16.
In a conventional brake control device, if the brake pedal stroke does not reach the predetermined position in a situation where regenerative braking is not possible, such as when the vehicle is stopped, or where the regenerative braking force is greatly limited, the friction braking force is in response to the driver request. And the brake fluid pressurized by pumping up must be supplied to the wheel cylinder, so that the frequency of operation of the pump increases. Further, in the event of an electrical failure that makes pumping impossible, braking force is not generated until the brake pedal stroke reaches a predetermined position, which gives the driver a feeling of strangeness. Furthermore, since there is a difference in the relationship between the brake pedal stroke and the braking force (deceleration) depending on the presence or absence of regenerative braking, the driver feels uncomfortable.
On the other hand, in the brake control device of the first embodiment, in a situation where regenerative braking is impossible, the stroke simulator valve 27 is not controlled and the inflow of the brake fluid from the master cylinder M / C to the reservoir 34 is restricted, so that Since the master cylinder pressure and the wheel cylinder pressure can be matched without operating the pump P, a friction braking force according to the driver's request can be generated. Since the stroke simulator valve 27 is a normally closed proportional solenoid valve, the valve closing state can be maintained in the event of an electrical failure, and the brake fluid is not stored in the reservoir 34. In addition, during regenerative cooperative control, the stroke simulator valve 27 and the pump 35 are constantly controlled to adjust the brake pedal stroke and master cylinder pressure to the driver's requirements. It is possible to control the relationship between the pedal stroke and the braking force, and to achieve the same good or pedal feel as a normal brake.

Since the pump 35 controls the brake fluid pressure of the brake piping system of the S system via the master cylinder M / C, the brake fluid pressure of the two systems can be adjusted using one pump 35.
Since the gate-out valve 12 is always uncontrolled during regenerative cooperative control, the control can be simplified as compared with the conventional brake control device.
The solenoid-in valves 19RL and 19RR corresponding to the wheel cylinders W / C (RL) and W / C (RR) of the left and right rear wheels RL and RR are always uncontrolled during regenerative cooperative control. In other words, the master cylinder M / C and the wheel cylinders W / C (RL), W / C (RR) of the left and right rear wheels RL, RR are always in communication, and the brake rigidity on the master cylinder side is reduced. Thus, an excessive increase in reaction force when the driver depresses the brake pedal BP can be reduced, and deterioration of the pedal feel can be suppressed.
In the first embodiment, the excess discharge amount of the pump 35 and the pump P is leaked from the stroke simulator valve 27 at the time of regenerative cooperative control, so that the brake pedal stroke and the master cylinder pressure can be adjusted corresponding to the driver request, and a good pedal feel is achieved. realizable.
Since the reservoir 34 can store more than the amount of brake fluid equivalent to the maximum regenerative braking force limit value of the left and right front wheels FL, FR, the brake that flows out of the master cylinder M / C until the regenerative braking force reaches the maximum regenerative braking force. The liquid can escape to the reservoir 34, and the regeneration efficiency can be maximized.
In addition, since the reservoirs 23P and 23S can store more than the amount of brake fluid equivalent to the maximum regenerative braking force limit value of the corresponding left and right front wheels FL and FR, when switching from friction braking force to regenerative braking force, the regenerative braking force is Until the maximum regenerative braking force is reached, the brake fluid flowing out from the wheel cylinders W / C (FL) and W / C (FR) can be stored in the reservoirs 23P and 23S, so that the regenerative efficiency can be maximized.

Next, the effect will be described.
The brake control device according to the first embodiment has the following effects.
(1) A negative pressure booster NPB that amplifies the brake operation force corresponding to the brake pedal stroke of the driver, and two systems (P system) with brake fluid pressure corresponding to the operation force amplified by the negative pressure booster NPB , S system) is supplied to the wheel cylinder W / C provided in the brake piping system to generate braking force, and the left and right front wheels FL, FR attached to the wheel cylinder W / C are regenerated. A brake control device used in a vehicle having a regenerative braking device (motor generator MG, inverter INV, battery BATT) that generates a braking force, and at least one of two brake piping systems (P system) A gate-out valve 12 disposed in a first brake circuit (lines 11 and 18) between the primary chamber 15a of the master cylinder M / C and the wheel cylinder W / C, and a first brake circuit. A branch oil passage 16 having a reflux oil passage portion 17 branching from between the primary chamber 15a and the gate-out valve 12, a stroke simulator valve 27 provided in the reflux oil passage portion 17, and a stroke simulator valve 27. A reservoir 34 into which the brake fluid from the master cylinder M / C flows, and a pump 35 that sucks the brake fluid through the reservoir 34 and discharges the brake fluid from the reflux oil passage portion 17 to the branch oil passage 16 are provided.
Therefore, in a situation where regenerative braking is impossible, the stroke simulator valve 27 is not controlled and the flow of brake fluid from the master cylinder M / C to the reservoir 34 is restricted, so that the master cylinder pressure and the pump P are not operated by the normal brake. Since the wheel cylinder pressure can be matched, a friction braking force according to the driver request can be generated, and the operation frequency of the pump P can be suppressed.
(2) The pump 35 is driven when the regenerative braking device is operated, and controls the brake fluid pressure in the brake piping system of the other system (S system) via the master cylinder M / C. The brake fluid pressure of the system can be adjusted.
(3) A second brake circuit (pipe lines 26, 30) that branches from between the branch point of the branch oil passage 16 and one side of the gate out valve 12 and is connected to the first brake circuit on the other side of the gate out valve 12 , 31), and a pump P provided in the second brake circuit for discharging the brake fluid toward the connection point between the first brake circuit and the second brake circuit, each pump P, 35 and the stroke simulator valve 27 Are used to control the brake fluid pressure and brake pedal stroke of the master cylinder M / C when the regenerative braking device is operated to a predetermined relationship (the relationship between the master cylinder pressure and the brake pedal stroke in the normal brake).
Therefore, a good pedal feel similar to that of the normal brake can be obtained even during regenerative cooperative control.

[Other Examples]
As mentioned above, although the form for implementing this invention was demonstrated based on the Example, the specific structure of this invention is not limited to the structure shown in the Example, The range which does not deviate from the summary of invention. Such design changes are included in the present invention.
For example, in the embodiment, the example in which the branch oil passage is provided in the P system is shown, but it may be provided in the S system. Moreover, you may provide in both systems.
In the embodiment, the regenerative wheel is the front wheel and the non-regenerative wheel is the rear wheel, but the regenerative wheel may be the rear wheel and the non-regenerative wheel may be the front wheel.
In the embodiment, an example in which the brake control device of the present invention is applied to an electric vehicle has been shown, but it can also be applied to a hybrid vehicle.
Further, the present invention can be applied to a hydraulic circuit that satisfies the following three conditions.
1. Brake fluid can be stored in the reservoir
2. Solenoid out valve can reduce wheel cylinder pressure of regenerative wheel
3. The pump can discharge the fluid in the reservoir. Fig. 26 shows a hydraulic circuit that satisfies the above three conditions. 26 shows a hydraulic circuit of a general ABS unit. Instead of the reservoir 23, the solenoid-in valve 19, and the pump P in FIG. 2, a reservoir 37, a solenoid-in valve 38 that is a normally open solenoid valve, and a plunger pump 39 are provided. The configuration is such that the gate-out valve 12, the pipe line 26, and the check valve 20 are omitted. Even in this configuration, the same effects as those of the first embodiment can be obtained.

Hereinafter, technical ideas other than the invention described in the scope of claims understood from the embodiments will be described.
(a) In the brake control device according to claim 1,
Between the wheel cylinder provided on the non-regenerative wheel and the first solenoid valve, a normally open second solenoid valve is provided,
The brake control device according to claim 1, wherein the second electromagnetic valve is always operated in an opening direction when the regenerative braking device is operated.
Therefore, by keeping the master cylinder and the non-regenerative wheel cylinder in constant communication and reducing the brake rigidity on the master cylinder side, excessive reaction force increase when the driver steps on the brake pedal is reduced. It is possible to suppress the deterioration of the pedal feel.
(b) In the brake control device according to claim 1,
The brake control device according to claim 1, wherein when the regenerative braking device is activated, an excess discharge amount of the first pump and the second pump is leaked from the control valve.
Therefore, the brake pedal stroke and the master cylinder pressure can be adjusted corresponding to the driver request, and a good pedal feel can be realized.
(c) In the brake control device according to claim 1,
The brake control device according to claim 1, wherein the reservoir is capable of storing more than a brake fluid amount corresponding to a maximum regenerative braking force limit value of two regenerative wheels.
Therefore, the regenerative efficiency when generating the regenerative braking force from the beginning of braking can be maximized.
(d) In the brake control device according to claim 1,
Providing a second reservoir on the suction side of the second pump of the second brake circuit;
The brake control device according to claim 2, wherein the second reservoir is capable of storing more than a brake fluid amount corresponding to a maximum regenerative braking force limit value of one regenerative wheel.
Therefore, the regenerative efficiency when switching from the friction braking force to the regenerative braking force can be maximized.

BATT battery (regenerative braking device)
INV inverter (regenerative braking device)
M / C master cylinder (tandem master cylinder)
MCU motor control unit (regenerative braking device)
MG motor generator (regenerative braking device)
NPB negative pressure booster (booster)
P pump (second pump)
W / C wheel cylinder
11 Pipe line (1st brake circuit)
12 Gate-out valve (first solenoid valve)
15a Primary chamber (first liquid chamber)
16 Branch oil passage
17 Reflux oil passage
18 pipeline (first brake circuit)
26 pipeline (second brake circuit)
27 Stroke simulator valve (control valve)
30 pipeline (second brake circuit)
31 Pipeline (second brake circuit)
34 Reservoir
35 pump

Claims (3)

A booster that amplifies the brake operation force corresponding to the brake pedal stroke of the driver;
A tandem master cylinder that generates a braking force by supplying a brake hydraulic pressure corresponding to the operation force amplified by the booster to a wheel cylinder provided in two brake piping systems provided in the vehicle;
A regenerative braking device that generates a regenerative braking force with respect to a wheel attached to the wheel cylinder;
A brake control device used for a vehicle having
A first solenoid valve provided in at least one of the two brake piping systems and disposed in a first brake circuit between a first fluid chamber of the tandem master cylinder and the wheel cylinder;
A branch oil passage having a reflux oil passage portion which is the first brake circuit and branches from between the first liquid chamber and the first electromagnetic valve;
A control valve provided in the reflux oil passage,
A reservoir into which brake fluid flows from the tandem master cylinder via the control valve;
A pump that sucks brake fluid through the reservoir and discharges the brake fluid from the reflux oil passage to the branch oil passage;
A brake control device comprising: The brake control device according to claim 1, wherein
The pump is driven when the regenerative braking device is operated, and controls the brake fluid pressure of the other brake piping system via the tandem master cylinder. The brake control device according to claim 2,
A second brake circuit that branches from between a branch point of the branch oil passage and one side of the first solenoid valve, and is connected to the first brake circuit on the other side of the first solenoid valve;
A second pump provided in the second brake circuit for discharging brake fluid toward a connection point between the first brake circuit and the second brake circuit;
With
A brake control device using the pumps and the control valve to control the brake fluid pressure of the tandem master cylinder and the brake pedal stroke in a predetermined relationship when the regenerative braking device is operated.

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