JP2019018769A - Brake control device and brake control method - Google Patents

Abstract

To provide a brake control device and a brake control method capable of securing the stability of a vehicle behavior during braking.SOLUTION: According to this invention, information based on a state of a road surface in contact with a wheel part of a vehicle is acquired. Then, linear control for controlling a current which energizes a boosting valve part located in a connection liquid passage connected to a foil cylinder part which can apply brake force to the wheel part and pulse control for controlling a time for which the boosting valve part is opened are switched in accordance with the acquired state of the road surface in contact with the wheel part.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a vehicle brake control device and a brake control method.

  Conventionally, in Patent Document 1, when the deceleration is insufficient, the pressure increase valve is switched from linear control to pulse control, thereby increasing the pressure increase rate of the brake fluid pressure to suppress the occurrence of insufficient pressure increase. Technology is disclosed.

JP 2006-103438 A

However, in Patent Document 1, even if it is possible to suppress insufficient deceleration, an unexpected excessive pressure increase may make it difficult to ensure the stability of the vehicle behavior during braking.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a brake control device and a brake control method capable of ensuring the stability of vehicle behavior during braking.

  In order to achieve the above object, the present invention obtains information based on the state of the grounding road surface of the wheel portion of the vehicle, and the pressure increasing valve in the connecting fluid passage connected to the wheel cylinder portion capable of applying a braking force to the wheel portion. The linear control for controlling the current to be supplied to the part and the pulse control for controlling the time for opening the pressure increasing valve part are switched according to the acquired state of the ground road surface of the wheel part.

  Therefore, by switching between linear control and pulse control according to the state of the ground road surface, it is possible to ensure vehicle braking and stability of behavior.

It is a circuit block diagram of the brake control apparatus of Example 1. FIG. 3 is a schematic diagram illustrating a configuration of a solenoid-in valve according to the first embodiment. FIG. 3 is an enlarged view of a main part of the solenoid-in valve according to the first embodiment. 3 is a flowchart illustrating a switching process between linear control and pulse control according to the first exemplary embodiment. 3 is a time chart showing ABS control in a high μ road according to the first embodiment. 3 is a time chart showing ABS control in the split μ road according to the first embodiment. 6 is a time chart showing ABS control in a split μ road according to a second embodiment. It is a figure showing schematic structure of the brake system of Example 3. FIG. 6 is a diagram illustrating a schematic configuration of a first unit according to Embodiment 3.

[Example 1]
[Circuit configuration]
FIG. 1 is a circuit configuration diagram of the brake control device according to the first embodiment.
The hydraulic control unit HU adjusts the braking force applied to each wheel of the vehicle. Based on the command from the brake control unit (control unit) BCU, the wheel cylinder W / C (RL) on the left rear wheel, The hydraulic pressures of the front wheel wheel cylinder W / C (FR), the left front wheel wheel cylinder W / C (FL), and the right rear wheel wheel cylinder W / C (RR) are increased, decreased or maintained.
The hydraulic control unit HU has a piping structure called X piping, which is composed of two systems, a P system and an S system. By adopting X piping, even if one piping system fails, the other piping system can be used to generate half of the braking force during normal operation. In addition, P attached to the end of the code | symbol of each site | part described in FIG. 1 shows P system, S shows S system, and RL, FR, FL, RR is a left rear wheel, a right front wheel, a left front wheel, and a 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” refers to a hydraulic circuit that returns the brake fluid supplied to the wheel cylinder W / C to the reservoir tank ZRSV via the master cylinder ZM / C. By the way, the hydraulic circuit that can return the brake fluid supplied to the wheel cylinder W / C directly to the reservoir tank ZRSV without going through the master cylinder ZM / C is called `` Open hydraulic circuit ''. That's it.
The brake pedal ZBP is connected to the master cylinder ZM / C via the input rod ZIR. The pedal depression force input to the brake pedal ZBP is boosted by the brake booster ZBB. The master cylinder ZM / C generates brake fluid pressure according to the output of the brake booster ZBB.
The wheel cylinder W / C (RL) for the left rear wheel RL and the wheel cylinder W / C (FR) for the right front wheel FR are connected to the S system, and the wheel cylinder W / C (for the left front wheel FL is connected to the P system. FL) and the wheel cylinder W / C (RR) of the right rear wheel RR are connected. In addition, pumps PP and PS are provided in the P system and the S system. The pumps PP and PS are driven by one motor M. In the first embodiment, the pumps PP and PS are plunger pumps.

The master cylinder ZM / C and the wheel cylinder W / C are connected by a pipeline 1 and a pipeline 2. Pipe line Z2S is branched into pipe lines Z2RL and 2FR. Pipe line Z2RL is connected to wheel cylinder W / C (RL), and pipe line Z2FR is connected to wheel cylinder W / C (FR). Pipe line Z2P branches into pipe lines Z2FL and 2RR, pipe line Z2FL is connected to wheel cylinder W / C (FL), and pipe line Z2RR is connected to wheel cylinder W / C (RR).
A gate-out valve Z3, which is a normally open proportional control valve, is provided on the pipe line Z1. A master cylinder hydraulic pressure sensor Z4 is provided at a position closer to the master cylinder than the gate-out valve Z3P of the P system pipe line Z1P. On the pipe line Z1, a pipe line Z4 is provided in parallel with the gate-out valve Z3. A check valve Z5 is provided on the pipe line Z4. Check valve Z5 allows the flow of brake fluid from master cylinder ZM / C to wheel cylinder W / C and prohibits the flow in the opposite direction.
A solenoid-in valve Z6, which is a normally open proportional control valve corresponding to each wheel cylinder W / C, is provided on the pipe line Z2. On the pipeline Z2, a pipeline Z7 is provided in parallel with the solenoid-in valve Z6. A check valve Z8 is provided on the pipe line Z7. The check valve Z8 allows the flow of brake fluid in the direction from the wheel cylinder W / C to the master cylinder ZM / C and prohibits the flow in the opposite direction.

The discharge side of the pump P and the pipe line Z2 are connected by a pipe line Z9. A discharge valve Z10 is provided on the pipe line Z9. The discharge valve Z10 allows the flow of brake fluid in the direction from the pump P toward the pipe line Z2, and prohibits the flow in the opposite direction.
The position on the master cylinder side of the gate-out valve Z3 of the pipe line Z1 and the suction side of the pump P are connected by the pipe line Z11 and the pipe line Z12. A pressure regulating reservoir Z13 is provided between the pipe line Z11 and the pipe line Z12.
A position on the wheel cylinder side of the solenoid in valve Z6 of the pipe line Z2 and the pressure regulating reservoir Z13 are connected by a pipe line Z14. Pipe line Z14S branches to pipe lines Z14RL and Z14FR, and pipe line Z14P branches to pipe lines Z14FL and Z14RR and is connected to the corresponding wheel cylinder W / C.
A solenoid-out valve Z15, which is a normally closed solenoid valve, is provided on the pipe line Z14.
The pressure adjustment reservoir Z13 includes a pressure-sensitive check valve Z16. The check valve Z16 prevents high pressure from being applied to the suction side of the pump P by prohibiting the flow of brake fluid into the reservoir when the pressure in the pipe line Z11 exceeds a predetermined pressure. To do. The check valve Z16 opens regardless of the pressure in the pipe Z11 when the pump P is activated and the pressure in the pipe Z12 becomes low, allowing the brake fluid to flow into the reservoir. To do.

The brake control unit BCU is used to detect wheel speeds detected by wheel speed sensors Sfl, Sfr, Srl, Srr (hereinafter collectively referred to as wheel speed sensors Sx) provided on each wheel, vehicle yaw rate, front and rear The vehicle state detected by the integrated sensor Sc that detects acceleration and the steering angle detected by the steering angle sensor Sst that detects the steering angle of the driver are input. The brake control unit BCU, when detecting the lock tendency of the wheel, performs an anti-lock brake control (hereinafter referred to as ABS control) that avoids the wheel lock, the target vehicle behavior based on the steering angle, and the actual vehicle behavior. A VDC control unit that performs vehicle behavior control (hereinafter referred to as VDC control) that approximates the target vehicle behavior by applying a yaw moment to the vehicle by brake hydraulic pressure when the vehicle behavior deviates, and road surface friction A road surface μ estimation unit that estimates a road surface μ that is a coefficient. The road surface μ estimation unit estimates the road surface μ from the equation of motion of the wheels.
(Formula 1)
I × (dω / dt) = (μ × W × R) -τ: Wheel motion equation
I: Wheel inertia
dω / dt: Wheel acceleration τ: Brake torque (calculated from wheel cylinder pressure and friction coefficient of brake pad)
μ: Road surface μ
W: Wheel load
R: Depending on tire radius
μ = (I × (dω / dt) + τ) / (W × R)
It is represented by The wheel cylinder pressure is calculated from the flow rate based on the master cylinder hydraulic pressure sensor Z4 and the valve opening time of the solenoid-in valve Z6 and the solenoid-out valve Z15. As for the estimation of the road surface μ, in the steering device, a method of estimating from the relationship between the steering torque and the road surface reaction force, or an estimated deceleration is calculated from the wheel speed of each wheel to estimate the average road surface μ of the vehicle. There is also a way to do it.

  The ABS control unit has a pressure reduction start threshold value and a pressure increase start threshold value.When the wheel speed falls below the pressure reduction start threshold value, the solenoid-in valve Z6 is closed and the solenoid-out valve Z15 is opened to open the wheel. When the cylinder pressure is reduced, the wheel cylinder pressure is maintained when it is between the pressure reduction start threshold and the pressure increase start threshold, and when the pressure increase start threshold is exceeded, the solenoid-in valve Z6 is opened to open the wheel cylinder pressure. Increase the pressure. In addition, when it is determined that the road surface μ of the right wheel and the left wheel is a split μ road, the wheel cylinder pressure on the high μ road side is the same as the wheel cylinder pressure when ABS control is performed on the low μ road side. The split μ road control is performed to stabilize the vehicle behavior. In the VDC control unit, when the target vehicle behavior and the actual vehicle behavior deviate more than a predetermined amount, the gate-out valve 3 is closed, the pump P is operated, the solenoid-in valve 6 of the desired wheel is opened, and the wheel cylinder Increase pressure.

[Solenoid In Valve]
FIG. 2 is a schematic diagram illustrating the configuration of the solenoid-in valve according to the first embodiment.
The solenoid-in valve Z6 includes a solenoid Z21 that generates an electromagnetic attractive force, a valve element Z22 that operates according to the electromagnetic attractive force, and a coil spring Z23 that urges the valve element Z22 in the valve opening direction (upward in FIG. 2). And a valve body Z24 that is connected to a master cylinder side pipe Z2a and a wheel cylinder side pipe Z2b on the pipe Z2 from the solenoid-in valve Z6. When the valve element Z22 moves downward in FIG. 2, the leading end of the valve element Z22 is seated on the seat Z26 formed on the valve body Z24, whereby the pipe line Z2a and the pipe line Z2b are closed. On the other hand, when the valve element Z22 moves upward in FIG. 2, the leading end of the valve element Z22 is detached from the seat Z26, so that the pipe line Z2a and the pipe line Z2b are opened. That is, the communication state (differential pressure) between the pipe line Z2a and the pipe line Z2b is determined according to the vertical position (valve lift amount) of the valve body Z22.

FIG. 3 is an enlarged view of a main part of the solenoid-in valve 6 according to the first embodiment.
In the valve body Z22, a force Fa corresponding to the differential pressure between the pressure on the upstream side of the solenoid-in valve Z6 (corresponding to the master cylinder hydraulic pressure) and the pressure on the downstream side (corresponding to the hydraulic pressure of the wheel cylinder) is shown in the upper part of FIG. Then, a force Fb corresponding to the electromagnetic attraction force of the solenoid Z21 acts on the lower side in FIG. 3, and a force Fc due to the urging force of the coil spring Z23 acts on the upper side in FIG. The differential pressure can be controlled to a desired value by controlling the current supplied to the solenoid Z21. That is, the urging force of the coil spring Z23 is uniquely determined according to the position of the valve body Z22. For this reason, if the current value is controlled to a predetermined value, the force due to the differential pressure that finally balances the electromagnetic attractive force according to the current value and the urging force of the coil spring Z23 acts on the valve body Z22. Until the valve body Z22 strokes, the flow rate through the gate-out valve Z3 is adjusted. Hereinafter, this is referred to as linear control of the solenoid-in valve Z6. For linear control, the current flowing to solenoid Z21 is pulsed from 0 ampere to the current that closes solenoid Z21, and the valve body Z22 strokes according to the valve opening time to adjust the flow rate that flows through solenoid-in valve Z6. It is possible. Hereinafter, this is referred to as pulse control of the solenoid-in valve Z6.

(Problems with linear control)
The feature of the linear control makes it possible to finely adjust the flow rate. Therefore, pulsation of the brake fluid can be suppressed. As a result, the vibration of the brake pedal and the sound when the solenoid-in valve Z6 is closed can be suppressed, so that the sound vibration performance is better than that of the pulse control. However, when adjusting the upstream / downstream differential pressure of solenoid-in valve Z6 by linear control, the flow rate is higher or lower than the target flow rate due to fluid pressure fluctuations in the master cylinder and individual differences of solenoid-in valve Z6. It may become. If a flow rate higher than the target flow rate is generated, the amount of liquid flowing toward the wheel cylinder increases, resulting in excessive pressure increase. In the case of excessive pressure increase, if the wheel cylinder hydraulic pressure is reduced in order to restore the large slip of the wheel to the small slip by the ABS control, the braking force is reduced and the stopping distance may be increased.

  In addition, braking on road surfaces (hereinafter referred to as split μ roads) having different road surface friction coefficients (hereinafter referred to as road surface μs) on the left and right sides of the vehicle causes a high braking force on the road surface μ due to excessive pressure increase. There is a possibility that it becomes stronger than the braking force of the low road surface μ. Then, since the vehicle is pulled toward the high road surface μ side, a moment is generated in the vehicle, which may cause a spin. On the other hand, if a flow rate smaller than the target flow rate is generated, the amount of brake fluid flowing to the wheel cylinder side is small, and therefore the pressure increase is too small. In the ABS control when the pressure increase is too small, the hydraulic pressure is lower than the target hydraulic pressure, so that the braking force is reduced and the stopping distance may be increased. Therefore, the control method of the solenoid-in valve Z6 is switched between linear control and pulse control according to the traveling situation.

(Switching between linear control and pulse control)
Next, switching processing between linear control and pulse control will be described. FIG. 4 is a flowchart illustrating a switching process between the linear control and the pulse control according to the first embodiment.
In step S1, an estimated deceleration is calculated, and it is determined whether the estimated deceleration is greater than a preset high μ pulse control execution determination threshold. Otherwise, go to step S2. Here, the estimated deceleration may be calculated based on, for example, the amount of change in wheel speed per unit time detected by the wheel speed sensor Sx, or may be calculated based on the longitudinal acceleration of the integrated sensor Sc. Good. Also, the high μ pulse control execution determination threshold is a value that can be determined as a high μ road, and when a deceleration larger than the high μ pulse control execution determination threshold is obtained, the high μ road is used. When the deceleration below the control execution determination threshold is obtained, it is determined that the road is a low μ road.

In step S2, it is determined whether or not the road is a split μ road. If it is determined that the road is a split μ road, the process proceeds to step S4. In determining whether the road is a split μ road, it is determined whether the left wheel estimated braking force and the right wheel estimated braking force are different from each other by a predetermined value or more. In particular,
(Left wheel estimated braking force)> (Right wheel estimated braking force + predetermined value)
Or
(Right wheel estimated braking force)> (Left wheel estimated braking force + predetermined value)
Judgment is made based on whether one of the above is satisfied.
The estimated braking force is a value obtained by multiplying the braking torque τ included in the wheel motion equation shown in (Expression 1) by the tire moving radius R. The predetermined value is a value representing a braking force difference generated between the low μ road and the high μ road. When the left and right wheel estimated braking force difference is more than the predetermined value, the vehicle tends to spin. Show.
In step S3, the solenoid-in valve Z6 is controlled by linear control.
In step S4, the control method of the solenoid-in valve Z6 is changed to pulse control.

  FIG. 5 is a time chart showing the ABS control in the high μ road according to the first embodiment. At time t1, ABS control is started by the driver's sudden braking, and the estimated deceleration is larger than the high μ pulse control execution determination threshold value, so the pulse control execution determination flag is turned on. Therefore, the target hydraulic pressure for pressure increase / holding / depressurization based on ABS control is set in each wheel, and pulse control is performed to achieve this target hydraulic pressure. That is, if it is determined that the road is a high μ road, and if linear control is selected, when an excessive flow rate occurs, the amount of pressure reduction becomes excessive during pressure reduction after pressure increase, and the stopping distance may increase as the braking force decreases. On the other hand, when pulse control is selected, even if an excessive flow rate occurs, the control is performed based on the valve opening time, so that the excessive flow rate state does not occur continuously. Therefore, it is possible to avoid excessive pressure reduction during pressure reduction after pressure increase, and to secure a braking force.

  FIG. 6 is a time chart showing the ABS control in the split μ road according to the first embodiment. At the time t1, when the ABS control is started by the driver's sudden braking, the estimated deceleration is a value smaller than the high μ pulse control execution determination threshold value, so the linear control is selected. At this time, a large difference is not detected in the road surface μ set by the left wheel and the right wheel. Thereafter, at time t2, if the left road surface μ is determined to be a high μ road, and if a split μ road is determined, the target hydraulic pressure of the left wheel on the high μ road side is the target liquid pressure of the right wheel on the low μ road side. A target hydraulic pressure that is substantially the same as the average value of the pressure is set. That is, on the high μ road side, since the wheel speed does not fall below the pressure reduction start threshold, it is not necessary to perform ABS control that repeats pressure reduction, maintenance, and pressure increase. However, in order to avoid an unnecessary yaw moment due to a difference in braking force between the left side and the right side, generation of a large braking force on the high μ road side is avoided. At this time, if linear control is continued and an excessive flow rate occurs, a large braking force is generated on the high μ road side, and the vehicle behavior may become unstable. Therefore, switching from linear control to pulse control is performed. As a result, even if an excessive flow rate occurs in the solenoid-in valve Z6, since the valve opening time is controlled, the excessive flow rate state does not continuously occur, and the stability of the vehicle behavior can be ensured.

As described above, in the first embodiment, the following operational effects can be obtained.
(1) Pipe line Z2 which is a connecting liquid path connected to a wheel cylinder W / C capable of applying a braking force to the vehicle wheel according to the brake hydraulic pressure, and a solenoid-in valve Z6 (pressure increasing valve) in the pipe line Z2. Input signal based on the state of the grounding road surface of the wheel section obtained, and linear control for controlling the current supplied to the solenoid-in valve Z6 and pulse control for controlling the time for opening the solenoid-in valve Z6. And a brake control unit BCU that switches according to the
Therefore, instability of vehicle behavior during braking can be suppressed.
(2) The brake control unit BCU switches to pulse control when the ground road surface friction coefficient is high compared to the low friction coefficient.
Therefore, it is possible to reduce the stop distance extension and the insufficient braking force caused by the excessive pressure reduction that occurs after the excessive pressure increase on the high μ road.
(3) The wheel portion includes a first wheel portion that is one of the left and right wheels of the vehicle, and a second wheel portion that is the other of the left and right wheels, and the brake control unit BCU has a first friction coefficient on the ground road surface. In the case of a split μ road where the second wheel portion is lower than the wheel portion, the control is switched to pulse control.
Therefore, it is possible to reduce the spin tendency due to the high μ side overpressure in the split μ road.

(4) The brake control unit BCU switches to pulse control during ABS control.
Therefore, during ABS control, it is possible to achieve both control that prioritizes sound vibration performance and control that prioritizes functional performance such as stopping distance and vehicle behavior stability.
(5) The brake control unit BCU switches to the pulse control when the deceleration of the vehicle is greater than the threshold value for determining the pulse control execution at high μ, which is a set threshold value.
Therefore, it is possible to reduce the stop distance extension and the insufficient braking force caused by the excessive pressure reduction that occurs after the excessive pressure increase on the high μ road.
(6) The wheel portion includes a first wheel portion that is one of the left and right wheels of the vehicle and a second wheel portion that is the other of the left and right wheels, and the brake control unit BCU is a control that is generated in the first wheel portion. When the power is larger than a value obtained by adding a predetermined value to the braking force generated in the second wheel portion, the control is switched to pulse control.
Therefore, it is possible to reduce the spin tendency due to the high μ side overpressure in the split μ road.

(Example 2)
Next, Example 2 will be described. Since the basic configuration is the same as that of the first embodiment, only different points will be described. FIG. 7 is a time chart showing ABS control in the split μ road according to the second embodiment. In Example 1, during deceleration on the split μ road, the control of the solenoid-in valve Z6 in all the wheels was changed from linear control to pulse control. In contrast, in the second embodiment, at the time of deceleration on the split μ road, only the solenoid-in valve Z6 corresponding to the rear wheel on the high μ road side is changed from linear control to pulse control. That is, in order to stabilize the vehicle behavior during braking, it is important to ensure the cornering force of the rear wheels. Further, during sudden braking, the load moves to the front wheel side, and the wheel load of the rear wheel decreases. Therefore, the friction circle of the rear wheel tends to be small, and the cornering force is likely to be lowered when the rear wheel is excessively pressurized. On the other hand, if the solenoid-in valves Z6 of all the wheels are pulse controlled as in the first embodiment, the sound vibration performance may be deteriorated. Therefore, in the second embodiment, when the road is split μ, only the rear wheel on the high μ road side is switched from linear control to pulse control, thereby ensuring the vehicle stability and suppressing the deterioration of sound vibration performance. did.

In Example 2, the following effects are obtained.
(7) The first wheel portion includes a first front wheel that is a front wheel of the vehicle and a first rear wheel that is a rear wheel of the vehicle, and the second wheel portion is a second front wheel that is a front wheel of the vehicle. A second rear wheel that is a rear wheel of the vehicle, and a solenoid-in valve Z6 includes a solenoid-in valve Z6FR corresponding to the first front wheel, a solenoid-in valve Z6FL corresponding to the first rear wheel, and a second front wheel The brake control unit BCU switches only the high μ road side to pulse control among the solenoid-in valves Z6RR and Z6RL, and the solenoid-in valve Z6RR corresponding to the second rear wheel.
Therefore, by switching the rear wheel of the high μ road side to pulse control for only one wheel, it is possible to stabilize the vehicle behavior and suppress the deterioration of sound vibration performance.
In the second embodiment, only the rear wheels on the high μ road side are switched to the pulse control, but at least one or more wheels may be switched to the pulse control. For example, only the front wheel on the high μ road side may be switched to pulse control, the front wheel and the rear wheel on the high μ road side may be switched to pulse control, or in addition to the front wheel and rear wheel on the high μ road side, The rear wheels may be switched to pulse control.

(Example 3)
Next, Example 3 will be described. In Example 1, the example applied to the brake control apparatus of a closed hydraulic circuit was demonstrated. On the other hand, in Example 3, it applied to the brake control apparatus of a brake-by-wire system. FIG. 8 is a diagram illustrating a schematic configuration of a brake system according to the third embodiment. FIG. 9 is a diagram illustrating a schematic configuration of a first unit according to the third embodiment. The brake system 1 according to the third embodiment includes a vehicle including only an internal combustion engine (engine) as a prime mover for driving wheels, a hybrid vehicle including an electric motor (generator) in addition to the engine, and an electric motor. This is a hydraulic brake system that can be mounted on an electric vehicle equipped only with a brake pedal 100 and a wheel cylinder 101 of wheels (left front wheel FL, right front wheel FR, left rear wheel RL, and right rear wheel RR). Arranged between. The brake system 1 supplies brake fluid as hydraulic fluid to the wheel cylinder 101, and generates fluid pressure (brake fluid pressure) in the wheel cylinder 101. The wheel cylinder 101 applies a friction braking force (hydraulic braking force) to the wheel according to the brake fluid pressure. The brake system 1 has two brake pipes. The piping type is X (diagonal) piping, but front and rear piping may be adopted. When distinguishing a member corresponding to the first system (primary system) and a member corresponding to the second system (secondary system), subscripts P and S are added to the end of each symbol. The members corresponding to the wheels FL to RR are appropriately distinguished by adding suffixes a to d at the end of the reference numerals.

  As shown in FIG. 8, the brake system 1 includes a first unit 1A and a second unit 1B. The first unit 1A and the second unit 1B are installed in an engine room or the like isolated from the cab of the vehicle by a dash panel or the like. The first unit 1A integrally includes a reservoir tank 2, a push rod 3, a master cylinder 4, and a stroke sensor 91. The first unit 1A is fixed to, for example, a dash panel. The first unit 1A does not include a negative pressure booster. Here, the negative pressure booster is a device that boosts a driver's brake operation force by using a negative pressure generated by a vehicle engine or a negative pressure pump provided separately. The second unit 1B integrally includes a hydraulic unit 5, a stroke simulator 6, hydraulic pressure sensors 92 and 93, and an electronic control unit 90. The first unit 1A and the second unit 1B are connected to each other by a plurality of pipes 10. The plurality of pipes 10 include a master cylinder pipe 10M (first pipe 10MP, second pipe 10MS) and a suction pipe 10R. Second unit 1B and wheel cylinder 101 of each wheel are connected to each other by a wheel cylinder pipe 10W.

  The reservoir tank 2 is a brake fluid source that stores brake fluid, and is opened to atmospheric pressure. As shown in FIG. 9, the reservoir tank 2 has a first wall 21, a second wall 22, and a third wall 23. Each of the walls 21 to 23 extends from the bottom 20 of the reservoir tank 2 to a predetermined height, and partitions the bottom 20 side in the reservoir tank 2 into a plurality of chambers. A first chamber 24 </ b> P is defined between the first wall 21 and the inner peripheral surface of the reservoir tank 2. A sensor chamber 25 is defined between the first wall 21 and the second wall 22. A second chamber 24S is defined between the second wall 22 and the third wall 23. A third chamber 26 is defined between the third wall 23 and the inner peripheral surface of the reservoir tank 2. The third wall 23 is higher than the first wall 21 and the second wall 22. Liquid level sensors 27 and 28 are installed in the sensor chamber 25 and the third chamber 26, respectively. Connectors 270 and 280 of the liquid level sensors 27 and 28 are installed on the outer surface of the bottom 20. A port 29 communicating with the third chamber 26 is provided on the side surface of the reservoir tank 2. One end of the suction pipe 10R is connected to the port 29. The push rod 3 is a member that converts the swing of the brake pedal 100 into a linear motion. One end of the push rod 3 is rotatably connected to the brake pedal 100. The push rod 3 has a flange 30. The collar portion 30 includes a tapered surface 300.

  The master cylinder 4 is a first hydraulic pressure source that operates in response to an operation of the brake pedal 100 by the driver and can supply hydraulic fluid pressure to the wheel cylinder 101. The master cylinder 4 includes a first cylinder 40, a piston 41, a spring unit 42, and seal members 43 and 44. The first cylinder 40 accommodates a piston 41 and the like. The reservoir tank 2 is installed above the first cylinder 40 in the vertical direction. 8 and 9, a cross section passing through the axis of the master cylinder 4 is shown. For convenience of explanation, the x-axis is provided in the moving direction (axial direction) of the piston 41, and the side on which the piston 41 moves in response to the depression operation of the brake pedal 100 is negative. As shown in FIG. 9, the inner periphery of the first cylinder 40 has a large diameter portion 401 and a small diameter portion 402. These portions 401 and 402 have a cylindrical shape and extend substantially in the x-axis direction on the same axis line (within manufacturing error). The large-diameter portion 401 is at the end of the first cylinder 40 on the x-axis positive direction side. The end of the large diameter portion 401 on the x axis positive direction side gradually decreases in diameter toward the x axis positive direction side. Thereby, a tapered surface 403 is formed. A hole 404 is opened at the center of the surface 403. The hole 404 extends in the x-axis direction on the axis and penetrates the inside and outside of the first cylinder 40. The diameter of the hole 404 is larger than the diameter of the portion 31 (on the side of the brake pedal 100 relative to the flange 30) in the push rod 3, and is smaller than the diameter of the flange 30. In the hole 404, the portion 31 of the push rod 3 is fitted. A rod-shaped guide member 910 is installed at a step portion between the large diameter portion 401 and the small diameter portion 402 at the end of the large diameter portion 401 on the negative x-axis direction side. The guide member 910 extends inside the large diameter portion 401 in the x-axis direction.

  The small diameter portion 402 is adjacent to the large diameter portion 401 on the x-axis negative direction side. The small-diameter portion 402 has a supply recess 405, a supply recess 406, and seal grooves 407 and 408 for each of the first and second systems. The first system supply recess 405P and the like are on the x-axis positive direction side of the small-diameter portion 402 and are adjacent to the large-diameter portion 401 on the x-axis negative direction side. The second system supply recess 405S and the like are on the x-axis negative direction side of the small-diameter portion 402, and are adjacent to the first system supply recess 405P and the like on the x-axis negative direction side. The recesses 405 and 406 and the grooves 407 and 408 are ring-shaped extending in the direction around the axis (hereinafter referred to as the circumferential direction). The supply recess 405 has a groove shape. The seal groove has a first groove 407 and a second groove 408, and these grooves 407 and 408 sandwich a supply recess 405 in the x-axis direction. The first groove 407 is on the x-axis positive direction side of the supply recess 405, and the second groove 408 is on the x-axis negative direction side of the supply recess 405. A first seal member 43 is installed in the first groove 407, and a second seal member 44 is installed in the second groove 408. The seal members 43 and 44 are ring-shaped packings having a U-shaped cross section. The first seal member 43S of the second system opens on the x-axis positive direction side, and the other seal members 43P, 44P, 44S open on the x-axis negative direction side. The supply recess 406 is adjacent to the supply recess 405 (second groove 408) on the x-axis negative direction side. The first cylinder 40 has a replenishment liquid path 45 and a supply liquid path 46 for each of the first and second systems. These liquid passages extend in the radial direction with respect to the axis (hereinafter referred to as radial direction) inside the first cylinder 40 and open to the small diameter portion 402 and open to the outer surface 400 of the first cylinder 40. The replenishment liquid path 45 opens in the replenishment recess 405, and the supply liquid path 46 opens in the supply recess 406. On the outer surface 400 of the first cylinder 40, the opening of the first supply liquid passage 45P is connected to the opening in the bottom 20 of the first chamber 24P of the reservoir tank 2, and the opening of the second supply liquid passage 45S is the reservoir. The tank 2 is connected to the opening in the bottom 20 of the second chamber 24S of the tank 2.

  The master cylinder 4 is a tandem type and has a piston 41 and a spring unit 42 for each of the first and second systems. The first piston 41P is accommodated inside the first cylinder 40 so as to be movable in the axial direction (x-axis direction) of the first cylinder 40, and is connected to the brake pedal 100 via the push rod 3. The first piston 41P may be directly connected to the brake pedal 100 without using the push rod 3. The second piston 41S is accommodated in the first cylinder 40 so as to be movable in the axial direction (x-axis direction) of the first cylinder 40, and is arranged in series with the first piston 41P. The second piston 41S is on the x-axis negative direction side with respect to the first piston 41P. The second piston 41S is a free piston type and interlocks with the first piston 41P. The outer periphery of the piston 41 is cylindrical, and its diameter is slightly smaller than the diameter of the small diameter portion 402. The diameters of the first and second pistons 41P and 41S (outer peripheral surfaces thereof) are substantially equal to each other. The lip of the seal members 43 and 44 is in contact with the outer peripheral surface of the piston 41.

  On the inner peripheral side of the piston 41, there are bottomed cylindrical concave portions 411 and 412 extending in the axial direction of the piston 41. The first recess 411 opens on one side in the axial direction of the piston 41, and the second recess 412 opens on the other side in the axial direction. The diameters of both concave portions 411 and 412 are substantially equal. There is a wall 413 separating the concave portions 411 and 412 at the bottom of the concave portions 411 and 412. A wall 413P of the first piston 41P has a hemispherical recess 414 on the first recess 411 side. The other end of the push rod 3 includes a hemispherical convex portion 32. The convex part fits into the concave part 414 and contacts the bottom surface of the concave part 414. A replenishment hole 415 is provided in the peripheral wall of the second recess 412 in the piston 41. The supply hole 415 extends in the radial direction with respect to the axis of the piston 41, penetrates the peripheral wall, and opens to the inner side (second recess 412) and the outer side (outer surface 410 of the piston 41). The replenishing holes 415 are located on the opening side of the bottom of the second recess 412, and a plurality (for example, four) of the replenishing holes 415 are arranged at substantially equal intervals around the axis of the piston 41.

  A first chamber 47P is partitioned inside the first cylinder 40 by a first piston 41P and a second piston 41S, and the second piston 41S is opposite to the first chamber 47P in the axial direction (on the negative side of the x axis). The second chamber 47S is partitioned, and the third chamber 48 is partitioned by the first piston 41P on the opposite side (x-axis positive direction side) in the axial direction with respect to the first chamber 47P. The first chamber 47P includes the second seal member 44P, the second seal member 44P on the outer peripheral surface of the first piston 41P, the x-axis negative direction side, the second recess 412P of the first piston 41P, the first seal member 43S, The second seal member 44P and the first seal member in the x-axis positive direction side of the first seal member 43S on the outer peripheral surface of the two piston 41S, the first recess 411S of the second piston 41S, and the small diameter portion 402 of the first cylinder 40 Defined by 43S (mainly the supply recess 406P). The second chamber 47S includes the second seal member 44S, the second seal member 44S on the outer peripheral surface of the second piston 41S, the x-axis negative direction side, the second recess 412S of the second piston 41S, and the small diameter of the first cylinder 40. The portion 402 is defined by the x-axis negative direction side (including the supply recess 406S) from the second seal member 44S. The third chamber 48 includes the first seal member 43P, the first seal member 43P on the outer peripheral surface of the first piston 41P, the positive side in the x-axis direction, the first recess 411P of the first piston 41P, and the size of the first cylinder 40. It is defined by the x-axis positive direction side of the first seal member 43P in the diameter portion 401. A supply liquid passage 46 is always open in the first chamber 47P and the second chamber 47S. The opening of the supply liquid passage 46 in the outer surface 400 of the first cylinder 40 functions as a port (connection port). One end of the first pipe 10MP is connected to the opening of the supply liquid passage 46P connected to the first chamber 47P. One end of the second pipe 10MS is connected to the opening of the supply liquid path 46S connected to the second chamber 47S.

  When the piston 41 moves along the inner peripheral surface of the first cylinder 40, the seal members 43 and 44 (lips thereof) are in sliding contact with the outer peripheral surface of the piston 41. The seal members 43 and 44 function as rod seals. The first seal member 43P suppresses the flow of brake fluid from the supply recess 405P toward the third chamber 48 on the outer peripheral side of the first piston 41P. The second seal member 44P suppresses the flow of brake fluid from the first chamber 47P toward the supply recess 405P on the outer peripheral side of the first piston 41P, and allows the flow of brake fluid in the reverse direction. The first seal member 43S suppresses the flow of brake fluid from the first chamber 47P toward the supply recess 405S on the outer peripheral side of the second piston 41S, and allows the flow of brake fluid in the reverse direction. The second seal member 44S suppresses the flow of brake fluid from the second chamber 47S to the supply recess 405S on the outer peripheral side of the second piston 41S, and allows the flow of brake fluid in the reverse direction.

  The spring unit 42 includes a spring (elastic body) 420, a first retainer 421, a second retainer 422, and a stopper 423. The spring 420 is a compression coil spring. The outer diameter of the spring 420 is slightly smaller than the inner diameter of the recesses 411 and 412 of the piston 41. The retainers 421 and 422 have a bottomed cylindrical shape, and include a cylindrical portion 424, a bottom portion 425, and a flange portion 426. The flange 426 extends in a disk shape from the opening side of the cylindrical portion 424 to the radially outer side. A hole 427 passes through the center of the bottom 425. The diameter of the outer periphery of the cylindrical portion 424 is slightly smaller than the diameter of the inner periphery of the spring 420. The axial dimension of the cylindrical portion 424 is larger in the second retainer 422 than in the first retainer 421. The stopper 423 has a rod shape, and the diameter of the main body thereof is slightly smaller than the diameter of the hole 427 in the bottom portion 425 of the second retainer 422. One end of the stopper 423 has a thin shaft portion 428 having a smaller diameter than the main body. The diameter of the thin shaft portion 428 is slightly smaller than the diameter of the hole 427 in the bottom portion 425 of the first retainer 421. The other end 429 of the stopper 423 has a columnar shape having a diameter larger than that of the main body, and the diameter thereof is slightly smaller than the diameter of the inner periphery of the cylindrical portion 424 of the second retainer 422, and the diameter of the hole 427 in the bottom portion 425 of the second retainer 422. Greater than.

  One end of the spring 420 surrounds the cylindrical portion 424 of the first retainer 421, and one end of the spring 420 is in contact with the flange 426 of the first retainer 421. The other end of the spring 420 surrounds the cylindrical portion 424 of the second retainer 422, and the other end of the spring 420 is in contact with the flange 426 of the second retainer 422. One end of the stopper 423 is fixed to the first retainer 421 by fitting the thin shaft portion 428 of the stopper 423 into the hole 427 in the bottom 425 of the first retainer 421. The main body of the stopper 423 is fitted in the hole 427 in the bottom portion 425 of the second retainer 422, and the other end 429 of the stopper 423 is on the inner peripheral side of the cylindrical portion 424 of the second retainer 422. Both ends of the spring 420 are held by retainers 421 and 422, respectively. The spring 420 is limited in its axial direction by the stopper 423 and is always pressed and contracted, and can be elastically deformed in a predetermined amount in the axial direction. When the other end 429 of the stopper 423 contacts the bottom 425 of the second retainer 422, the maximum length of the spring 420 is limited. The main body of the stopper 423 moves along the inner periphery of the hole 427 in the bottom 425 of the second retainer 422, and the other end 429 of the stopper 423 moves along the inner periphery of the cylindrical portion 424 of the second retainer 422. The deformation of the spring 420 is guided in the axial direction.

  The first spring unit 42P is accommodated in the first chamber 47P, and the second spring unit 42S is accommodated in the second chamber 47S. The axial dimension of the first spring unit 42P (second retainer 422 and stopper 423) is smaller than the axial dimension of the second spring unit 42S (second retainer 422 and stopper 423). The x-axis positive direction side of the first spring unit 42P is fitted into the second recess 412P of the first piston 41P, and the flange 426 of the first retainer 421P is in contact with the bottom (wall 413P) of the second recess 412P. The x-axis negative direction side of the first spring unit 42P fits into the first recess 411S of the second piston 41S, and the flange 426 of the second retainer 422 contacts the bottom (wall 413S) of the first recess 411S. The x-axis positive direction side of the second spring unit 42S is fitted in the second recess 412S of the second piston 41S, and the flange 426 of the first retainer 421S is in contact with the bottom (wall 413S) of the second recess 412S. The x-axis negative direction side of the second spring unit 42S (the flange 426 of the second retainer 422) is in contact with the bottom of the first cylinder 40 on the x-axis negative direction side. The spring 420P (first elastic body) of the first spring unit 42P is compressed between the first piston 41P and the second piston 41S in the first chamber 47P while being compressed in the axial direction of the first cylinder 40. It is in. The spring 420S (second elastic body) of the second spring unit 42S is compressed inside the second chamber 47S in the axial direction of the first cylinder 40 and the inner surfaces of the second piston 41S and the first cylinder 40. Between. The spring 420P always urges the first piston 41P to the x-axis positive direction side, and the spring 420S functions as a return spring that always urges the second piston 41S to the x-axis positive direction side. The set load of the spring 420P is less than or equal to the set load of the spring 420S. The spring 420 may be an elastic body, and is not limited to a coil spring but may be a disc spring or the like. The material of the spring 420 is not limited to metal, and may be non-metal such as rubber.

  When the flange 30 (the surface 300) of the push rod 3 comes into contact with the periphery (the surface 403) of the hole 404 of the first cylinder 40, the push rod 3 moves in the positive x-axis direction, that is, both pistons 41P, The movement of 41S in the positive x-axis direction is restricted. In this state, that is, in an initial state in which both pistons 41P and 41S are displaced maximum in the positive direction of the x-axis, the opening of the supply hole 415 on the outer peripheral surface of the piston 41 is the lip of the first seal member 43 and the second in the x-axis direction. It is located between the lip of the seal member 44 (between the supply recess 405 and the lip of the second seal member 44), and communicates with the supply liquid passage 45. The first chamber 24P of the reservoir tank 2 is connected to the first chamber 47P of the master cylinder 4 via a replenishment liquid path 45P, a replenishment recess 405P, and a replenishment hole 415P. The second chamber 24S of the reservoir tank 2 is connected to the second chamber 47S of the master cylinder 4 via the replenishment liquid path 45S, the replenishment recess 405S, and the replenishment hole 415S.

  The stroke sensor 91 includes a magnet holder 911, a magnet 912, and a sensor body 913. The magnet 912 is installed in the magnet holder 911. The magnet holder 911 (magnet 912) is installed at the positive end of the first piston 41P in the x-axis direction. A guide member 910 is fitted in the magnet holder 911. The sensor body 913 includes a detection unit such as a Hall element and a connector 914. The sensor body 913 is installed on the outer surface 400 of the first cylinder 40. The swing of the brake pedal 100 is converted into movement in the x-axis direction of the push rod 3 and the first piston 41P. When the first piston 41P moves in the x-axis direction, the magnet 912 also moves in the x-axis direction by the same amount. The detection unit of the sensor body 913 is located at a position overlapping the magnet 912 in the circumferential direction of the first cylinder 40, and generates an electrical signal in accordance with the movement of the magnet 912. Thereby, the stroke sensor 91 detects the movement amount (pedal stroke) of the first piston 41P in the x-axis direction. The circumferential displacement of the magnet 912 relative to the detection portion of the sensor body 913 is regulated by a guide member 910 that fits in the magnet holder 911. Thereby, the detection accuracy of the stroke sensor 91 is improved.

  As shown in FIG. 8, the hydraulic unit 5 includes a housing 50, a motor 80, a pump 8, a plurality of electromagnetic valves 71, and the like. The housing 50 accommodates valve bodies such as the pump 8 and the electromagnetic valve 71 therein. Inside the housing 50 is a circuit (brake hydraulic circuit) of the above-mentioned two systems (first system and second system) through which the brake fluid flows. This circuit includes a plurality of fluid paths. A plurality of ports are opened in the outer surface 500 of the housing 50. The plurality of ports are continuous with the liquid passages inside the housing 50, and connect these liquid passages to a liquid passage outside the housing 50 (such as a pipe 10M). The plurality of ports include a master cylinder port 51 (first port 51P, second port 51S), a wheel cylinder port 52, a suction port 53, a positive pressure port 54, a back pressure port 55, and a supply port 56. The other end of the first pipe 10MP is connected to the first port 51P. The other end of the second pipe 10MS is connected to the second port 51S. One end of a wheel cylinder pipe 10W is connected to the wheel cylinder port 52. The other end of the suction pipe 10R is connected to the suction port 53.

  The motor 80 is an electric motor having a rotation shaft, and is installed on one side of the housing 50. The motor 80 may be a motor with a brush, or may be a brushless motor provided with a resolver that detects the rotation angle or the number of rotations of the rotating shaft. The pump 8 is driven by a motor 80 and is a second hydraulic pressure source that can supply hydraulic fluid pressure to the wheel cylinder 101. The pump 8 is commonly used in the first system and the second system. The pump 8 is a plunger pump and includes a plurality of (for example, five) cylinders (plungers). The pump 8 may be a gear pump or the like. The electromagnetic valve is a control valve that operates according to a control signal, and includes a solenoid and a valve body. The valve body strokes in response to energization of the solenoid, and switches between opening and closing the liquid path (connecting and disconnecting the liquid path). The solenoid valve generates a control hydraulic pressure by controlling the communication state of the circuit and adjusting the flow state of the brake fluid. The plurality of solenoid valves include a shut-off valve 71, a pressure increasing valve 72, a communication valve 73, a pressure regulating valve 74, a pressure reducing valve 75, a simulator out valve 77, and a simulator in valve 78. The shut-off valve 71 (first valve 71P, second valve 71S), the pressure increasing valve 72, and the pressure regulating valve 74 are normally open valves that are opened in a non-energized state. The communication valve 73, the pressure reducing valve 75, the simulator-out valve 77, and the simulator-in valve 78 are normally closed valves that close in a non-energized state. The shut-off valve 71, the pressure increasing valve 72, and the pressure regulating valve 74 are proportional control valves in which the opening degrees of the valves are adjusted according to the current supplied to the solenoid. The communication valve 73, the pressure reducing valve 75, the simulator-out valve 77, and the simulator-in valve 78 are on / off valves that are controlled to be switched in a binary manner. These valves may be proportional control valves. There is an oil filter on the input side or output side of the brake fluid for each valve 71 and the like.

  The plurality of liquid paths are a supply liquid path 11 (first liquid path 11P, second liquid path 11S), suction liquid path 12, discharge liquid path 13, pressure adjusting liquid path 14, pressure reducing liquid path 15, and positive pressure liquid path 16. , A back pressure liquid path 17, a back pressure supply liquid path 18, and a replenishment liquid path 19. The supply liquid path 11 has a first liquid path 11P and a second liquid path 11S. One end side of the first liquid path 11P is connected to the first port 51P. The other end side of the first liquid path 11P branches into a liquid path 11a for the front left wheel and a liquid path 11d for the rear right wheel. Each fluid path 11a, 11d is connected to a corresponding wheel cylinder port 52a, 52d. One end side of the second liquid path 11S is connected to the second port 51S. The other end side of the second liquid passage 11S branches into a liquid passage 11b for the front right wheel and a liquid passage 11c for the rear left wheel. Each fluid path 11b, 11c is connected to a corresponding wheel cylinder port 52b, 52c. A shutoff valve 71 is provided at the one end side of the supply liquid passage 11. In the supply liquid passage 11, an orifice 111 is provided on the master cylinder port 51 side with respect to the shutoff valve 71. There is a pressure increasing valve 72 in each of the liquid passages 11a to 11d. In each of the liquid passages 11a to 11d, an orifice 112 is provided on the side of the shutoff valve 71 with respect to the pressure increasing valve 72. There is a bypass liquid path 110 in parallel with each of the liquid paths 11a to 11d, bypassing the pressure increasing valve 72 (and the orifice 112). There is a check valve 720 in the liquid passage 110. The valve 720 only allows the flow of brake fluid from the wheel cylinder port 52 side toward the master cylinder port 51 side.

  The suction liquid path 12 connects the liquid storage chamber 57 and the suction port 81 of the pump 8. The liquid reservoir chamber 57 communicates with a suction port 53 that opens to the outer surface 500 of the housing 50. The liquid reservoir chamber 57 is a volume chamber on the suction liquid passage 12, and functions as a reservoir inside the housing 50. One end side of the discharge liquid passage 13 is connected to a discharge port 82 of the pump 8. The other end side of the discharge liquid path 13 branches into a liquid path 13P for the first system and a liquid path 13S for the second system. Each of the liquid passages 13P and 13S is connected between the shutoff valve 71 and the pressure increasing valve 72 in the supply liquid passage 11. Each fluid passage 13P, 13S has a communication valve 73. In each of the liquid passages 13P and 13S, an orifice 131 is provided on the supply liquid passage 11 side with respect to the communication valve 73. The fluid passages 13P and 13S connect the first fluid passage 11P (on the wheel cylinder port 52 side with respect to the shutoff valve 71P) and the second fluid passage 11S (on the wheel cylinder port 52 side with respect to the shutoff valve 71S). Functions as a communication path. The pump 8 is connected to each wheel cylinder port 52 via the communication path (discharge liquid paths 13P, 13S) and the supply liquid paths 11P, 11S. The pressure adjusting liquid path 14 connects the pump 8 and the communication valve 73 in the discharge liquid path 13 to the liquid reservoir chamber 57. The liquid passage 14 has a pressure regulating valve 74 as a first pressure reducing valve. The decompression liquid path 15 connects the liquid reservoir chamber 57 between the pressure increasing valve 72 and the wheel cylinder port 52 in each of the liquid paths 11a to 11d of the supply liquid path 11. The liquid passage 15 has a pressure reducing valve 75 as a second pressure reducing valve. In each of the liquid passages 15a to 15d, an orifice 151 is provided on the liquid reservoir chamber 57 side with respect to the pressure reducing valve 75.

  The positive pressure liquid path 16 connects the first pressure path 54 between the first port 51P and the shutoff valve 71P in the first liquid path 11P. One end of the back pressure liquid passage 17 is connected to the back pressure port 55. The other end of the liquid path 17 is connected to the liquid reservoir chamber 57. There is a simulator out valve 77 in the liquid passage 17. In the liquid passage 17, an orifice 171 is provided on the back pressure port 55 side with respect to the simulator out valve 77. There is a bypass liquid path 170 in parallel with the liquid path 17 bypassing the simulator out valve 77 (and the orifice 171). There is a check valve 770 in the fluid path 170. The valve 770 allows only the flow of brake fluid from the liquid reservoir chamber 57 side to the back pressure port 55 side. The back pressure supply fluid path 18 branches from between the back pressure port 55 in the back pressure fluid path 17 and the simulator out valve 77, and between the shutoff valve 71P and the pressure increasing valves 72a, 72d in the first fluid path 11P. Connecting. The liquid path 18 has a simulator-in valve 78. In the liquid path 18, an orifice 181 is provided on the side of the first liquid path 11P with respect to the simulator-in valve 78. There is a bypass liquid path 180 in parallel with the liquid path 18 bypassing the simulator-in valve 78 (and the orifice 181). There is a check valve 780 in the liquid path 180. The valve 780 only allows the flow of brake fluid from the back pressure fluid passage 17 side toward the first fluid passage 11P side. The replenishment liquid path 19 connects the liquid reservoir chamber 57 and the replenishment port 56. In the third embodiment, a part of the replenishment liquid path 19 is common to the decompression liquid path 15.

  Between the pump 8 and the communication valve 73 in the discharge liquid passage 13, there is a liquid pressure sensor 92 that detects the liquid pressure (pump discharge pressure) at this location. Between the shut-off valve 71P and the pressure increasing valves 72a and 72d in the first fluid path 11P, there is a fluid pressure sensor 93P that detects the fluid pressure at this location (corresponding to the wheel cylinder fluid pressure). Between the shutoff valve 71S and the pressure increasing valves 72b and 72c in the second fluid passage 11S, there is a fluid pressure sensor 93S that detects the fluid pressure at this location (corresponding to the wheel cylinder fluid pressure).

  The stroke simulator 6 operates in accordance with the driver's braking operation, and can apply a reaction force and a stroke to the brake pedal 100. The stroke simulator 6 includes a second cylinder 60, a third piston 61, a first spring unit 62, a second spring unit 63, and seal members 64 and 65. The second spring unit 63 includes a lid member 66. The second cylinder 60 accommodates the third piston 61 and the like, and is installed on one side of the housing 50. In FIG. 8, the cross section which passes along the axis line of the stroke simulator 6 is shown. For convenience of explanation, the y-axis is provided in the moving direction (axial direction) of the third piston 61, and the side on which the third piston 61 moves in accordance with the depression operation of the brake pedal 100 is negative.

  The inner circumference of the second cylinder 60 has a small diameter part 601 and a large diameter part 602. These parts 601 and 602 are cylindrical and extend in the y-axis direction on substantially the same axis. The small-diameter portion 601 is on the y-axis positive direction side of the second cylinder 60 and has a supply recess 603, a communication groove 604, and seal grooves 605 and 606. The recesses 603, 604, 606 are on the y axis negative direction side of the small diameter portion 601. The recess 603 and the grooves 604 to 606 are annular extending in the direction around the axis (hereinafter referred to as the circumferential direction). The seal groove has a first groove 605 and a second groove 606, and these grooves 605 and 606 sandwich the supply recess 603 in the y-axis direction. The first groove 605 is on the positive y-axis side of the supply recess 603, and the second groove 606 is on the negative y-axis side of the supply recess 603. A first seal member 64 is installed in the first groove 605, and a second seal member 65 is installed in the second groove 606. The seal members 64 and 65 are annular and have a U-shaped cross section. The first seal member 64 opens on the y-axis positive direction side, and the second seal member 65 opens on the y-axis negative direction side. The communication groove 604 is located between the supply recess 603 and the second groove 606 in the y-axis direction and connects them. The diameter of the communication groove 604 is smaller than the diameter of the supply recess 603. The large diameter portion 602 is on the y axis negative direction side of the second cylinder 60 and is adjacent to the small diameter portion 601 on the y axis negative direction side. The y-axis negative direction end of the large diameter portion 602 opens to the outer surface 600 of the second cylinder 60. This opening is closed by a lid member 66. The outer periphery of the lid member 66 is cylindrical. On the outer periphery of the lid member 66, there is a seal groove 660 extending in the direction around the axis. An O-ring 67 is installed in the seal groove 660. The O-ring 67 is in contact with the large diameter portion 602.

  The second cylinder 60 has a positive pressure liquid path 691, a back pressure liquid path 692, a replenishment liquid path 693, and discharge liquid paths 694 and 695. These liquid passages 691 and the like extend inside the second cylinder 60 in the radial direction (hereinafter referred to as the radial direction) with respect to the axis and open to the small diameter portion 601 or the large diameter portion 602 and to the outer surface 600 of the second cylinder 60. Open. Bleeder valves 681 and 682 are installed in openings of the drainage channels 694 and 695 on the outer surface 600, respectively. The positive pressure liquid path 691 and the first discharge liquid path 694 open to the y axis positive direction side of the small diameter portion 601 (the y axis positive direction side from the first groove 605), and the back pressure liquid path 692 and the second discharge liquid path 695. Opens on the positive side of the large-diameter portion 602 in the y-axis direction. The replenishment liquid passage 693 opens into the replenishment recess 603.

  The third piston 61 is accommodated in the second cylinder 60 so as to be movable in the axial direction (y-axis direction) of the second cylinder 60. The outer periphery of the third piston 61 is cylindrical. The diameter of the third piston 61 (the outer peripheral surface thereof) is slightly smaller than the diameter of the small diameter portion 601, and is substantially equal to the diameters of the first and second pistons 41P and 41S (the outer peripheral surface thereof). The lip of the seal members 64 and 65 is in contact with the outer peripheral surface of the third piston 61. On the inner peripheral side of the third piston 61, there is a bottomed cylindrical recess 61 (611, 612) extending in the axial direction of the third piston 61. The first recess 611 opens on one side in the axial direction of the third piston 61, and the second recess 612 opens on the other side in the axial direction. The diameters of both concave portions 611 and 612 are substantially equal. At the bottom of both recesses 611 and 612, there is a wall 613 that separates both recesses 611 and 612. The wall 613 has a columnar convex portion 614 that protrudes toward the second concave portion 612. A supply hole 615 is provided in the peripheral wall of the first recess 611 in the third piston 61, and a supply hole 616 is provided in the peripheral wall of the second recess 612. Both holes 615 and 616 extend in the radial direction with respect to the axis of the piston 61, penetrate the peripheral wall, and open to the inner side (recessed portions 611 and 612) and the outer side (the outer surface 610 of the piston 61). A plurality of (for example, four) holes 615 and 616 are arranged at substantially equal intervals in the direction around the axis of the piston 61. The supply hole 615 is closer to the opening side than the bottom side of the first recess 611. The supply hole 616 is located on the bottom side of the second recess 612 rather than the opening side.

  A positive pressure chamber 607 is partitioned by the third piston 61 inside the second cylinder 60, and the back pressure chamber 608 is opposite to the positive pressure chamber 607 in the axial direction of the second cylinder 60 (y-axis negative direction side). Is partitioned. The positive pressure chamber 607 includes the first seal member 64, the first seal member 64 on the outer peripheral surface 610 of the third piston 61, the y-axis positive direction side, the first recess 611 of the third piston 61, and the second cylinder 60. The small-diameter portion 601 is defined by the y-axis positive direction side of the first seal member 64. The back pressure chamber 608 includes the second seal member 65 and the second seal member 65 on the outer peripheral surface 610 of the third piston 61 in the negative y-axis direction, the second recess 612 of the third piston 61, and the small diameter of the second cylinder 60. The portion 601 is defined by the y-axis negative direction side of the second seal member 65, the large-diameter portion 602 is defined by the y-axis positive direction side of the O-ring 67, and the lid member 66. A positive pressure fluid path 691 is always open in the positive pressure chamber 607, and a back pressure liquid path 692 is always open in the back pressure chamber 608. The openings of the positive pressure fluid passage 691, the replenishment fluid passage 693, and the back pressure fluid passage 692 in the outer surface 600 of the second cylinder 60 function as ports. A positive pressure port 54 of the hydraulic pressure unit 5 is connected to the opening of the positive pressure fluid passage 691. A supply port 56 of the hydraulic unit 5 is connected to the opening of the supply liquid passage 693. A back pressure port 55 of the fluid pressure unit 5 is connected to the opening of the back pressure fluid passage 692.

  When the third piston 61 moves along the inner peripheral surface of the second cylinder 60, the seal members 64 and 65 are in sliding contact with the outer peripheral surface 610 of the third piston 61. The seal members 64 and 65 function as rod seals. The first seal member 64 suppresses the flow of brake fluid from the positive pressure chamber 607 toward the supply recess 603 on the outer peripheral side of the third piston 61, and allows the flow of brake fluid in the reverse direction. The second seal member 65 suppresses the flow of brake fluid from the back pressure chamber 608 to the communication groove 604 (replenishment recess 603) on the outer peripheral side of the third piston 61, and allows the flow of brake fluid in the reverse direction.

  The first spring unit 62 includes a first spring 620, a first retainer 621, a second retainer 622, a stopper 623, and a first elastic member 62A. The configurations of the first spring 620, the first retainer 621, the second retainer 622, and the stopper 623 are the same as those of the spring 420, the first retainer 421, the second retainer 422, and the stopper 423 of the spring unit 42 of the master cylinder 4, respectively. is there. The first elastic member 62A is formed in a cylindrical shape using rubber (resin) as a material. The second spring unit 63 includes a second spring 630, a third retainer 631, a lid member 66, and a second elastic member 63A. The second spring 630 is a compression coil spring. The diameter, material diameter, axial dimension, and spring coefficient of the second spring 630 are larger than those of the first spring 620, respectively. Similar to the first retainer 621, the third retainer 631 has a bottomed cylindrical shape, and includes a cylindrical portion 632, a bottom portion 633, and a flange portion 634. The diameter of the outer periphery of the cylindrical portion 632 is slightly smaller than the diameter of the inner periphery of the second spring 630. The lid member 66 has a bottomed cylindrical shape. There is a convex portion 661 protruding from the bottom of the lid member 66. The convex portion 661 has a bottomed cylindrical shape and has a concave portion 662. Between the inner periphery of the lid member 66 and the outer periphery of the convex portion 661, there is a bottomed annular concave portion 663. The second elastic member 63A is made of rubber (resin) as a material and is formed in a cylindrical shape with a constricted center in the axial direction of the outer periphery.

  Both spring units 62 and 63 are accommodated in the back pressure chamber 608. The y-axis positive direction side of the first spring unit 62 is fitted in the second recess 612 of the third piston 61. The convex portion 614 of the third piston 61 is fitted to the inner periphery of the cylindrical portion 624 of the second retainer 622, and the flange portion 626 of the second retainer 622 is in contact with the bottom portion (wall 613) of the second concave portion 612. The first elastic member 62A is accommodated on the inner peripheral side of the cylindrical portion 624. One end surface of the first elastic member 62A in the axial direction is in contact with the convex portion 614. The y-axis negative direction side of the first spring unit 62 is fitted into the cylindrical portion 632 of the third retainer 631, and the flange portion 626 of the first retainer 621 is in contact with the bottom portion 633 of the third retainer 631. The y-axis positive direction side of the second spring 630 surrounds the cylindrical portion 632 of the third retainer 631, and the y-axis positive direction end of the second spring 630 is in contact with the flange portion 634 of the third retainer 631. The y-axis negative direction side of the second spring 630 surrounds the convex part 661 of the lid member 66 and fits into the concave part 663, and the y-axis negative direction end of the second spring 630 is in contact with the bottom part of the concave part 663. The second elastic member 63A is accommodated in the inner periphery (concave portion 662) of the convex portion 661 of the lid member 66. One end of the second elastic member 63A in the axial direction is in contact with the bottom surface of the concave portion 662, and the other end side projects from the convex portion 661 into the back pressure chamber 608. The first spring 620 and the second spring 630 are compressed in the axial direction of the second cylinder 60 inside the back pressure chamber 608, and function as the third piston 61 and the lid member 66 (the inner surface of the second cylinder 60). The surface of the lid member 66 on the positive side in the y-axis direction). Both springs 620 and 630 function as a return spring that constantly urges the third piston 61 toward the positive y-axis direction. The set load of the first spring 620 is less than or equal to the set load of the second spring 630. The springs 620 and 630 only need to be elastic bodies, and are not limited to coil springs and may be disc springs or the like. The material of the springs 620 and 630 is not limited to metal, and may be non-metal such as rubber.

  The movement of the third piston 61 in the y-axis positive direction side is restricted by the third piston 61 (in the y-axis positive direction end surface) being in contact with the inner surface of the second cylinder 60 (the inner peripheral side y-axis positive direction end surface). Is done. In this state, that is, in the initial state in which the third piston 61 is displaced to the maximum in the y-axis positive direction, the opening of the supply hole 615 in the outer peripheral surface of the third piston 61 is the positive pressure liquid path 691 in the small diameter portion 601 in the y-axis direction. And communicates with the positive pressure liquid passage 691. In the initial state, the opening of the supply hole 616 on the outer peripheral surface of the third piston 61 overlaps with the second groove 606 in the small diameter portion 601 in the y-axis direction, and the second seal member 65 is interposed via the second groove 606. Communicates with the communication groove 604 and the supply recess 603 on the positive side of the y-axis from the lip. In the initial state, there is a predetermined gap between the other end surface of the first elastic member 62A in the axial direction and the other end 629 of the stopper 623, and the other end surface of the second elastic member 63A in the axial direction and the third retainer 631 There is a predetermined gap between the bottom 633.

  The first chamber 47P of the master cylinder 4 includes a supply liquid path 46P of the first cylinder 40, a supply liquid path in the first pipe 10MP, a first liquid path 11P in the housing 50, and a supply liquid in the wheel cylinder pipes 10Wa and 10Wd. The wheel cylinders 101a and 101d are connected via a path. The second chamber 47S is connected via the supply liquid path 46S of the first cylinder 40, the supply liquid path in the second pipe 10MS, the second liquid path 11S of the housing 50, and the supply liquid paths in the wheel cylinder pipes 10Wb and 10Wc. The wheel cylinders 101b and 101c are connected. The first chamber 47P of the master cylinder 4 includes a supply liquid path 46P of the first cylinder 40, a supply liquid path in the first pipe 10MP, a first liquid path 11P and a positive pressure liquid path 16 of the housing 50, and a second cylinder 60. The positive pressure chamber 607 of the stroke simulator 6 is connected via the positive pressure liquid passage 691. The back pressure chamber 608 of the stroke simulator 6 is connected to the liquid reservoir chamber 57 via the back pressure liquid passage 692 of the second cylinder 60 and the back pressure liquid passage 17 of the housing 50. The back pressure chamber 608 includes a back pressure liquid path 692 of the second cylinder 60, a back pressure liquid path 17 of the housing 50, a back pressure supply liquid path 18, a supply liquid path 11, and a supply liquid path in the wheel cylinder pipe 10W. To the wheel cylinder 101. In the initial state, the back pressure chamber 608 is connected to the supply hole 616 of the third piston 61, the communication groove 604 of the second cylinder 60, the supply recess 603, the supply liquid path 693, and the supply liquid path 19 of the housing 50. , Connected to the liquid storage chamber 57.

  With the driver's brake operation, brake fluid pressure is generated in the first chamber 47P and the second chamber 47S of the master cylinder 4. Each chamber 47P, 47S functions as a hydraulic chamber. The reservoir tank 2 replenishes the chambers 47P and 47S with brake fluid. The brake fluid that has flowed out of each chamber 47P, 47S can be supplied to each wheel cylinder 101 via the supply fluid passage 11 (such as the second unit 1B). That is, the brake system 1 can supply the master cylinder hydraulic pressure to each wheel cylinder 101. The system 1 can pressurize the wheel cylinders 101a and 101d through the first liquid passage 11P by the master cylinder hydraulic pressure generated in the first chamber 47P. Further, the wheel cylinders 101b and 101c can be pressurized via the second liquid passage 11S by the master cylinder hydraulic pressure generated in the second chamber 47S. The brake fluid flowing out from the first chamber 47P can be supplied to the stroke simulator 6. By supplying the brake fluid, the stroke simulator 6 artificially generates an operation reaction force (pedal reaction force) of the brake pedal 100. Thus, the master cylinder 4, the reservoir tank 2, and the stroke simulator 6 function as a brake device.

  An electronic control unit (control unit; hereinafter referred to as ECU) 90 is installed on one side of the housing 50. The ECU 90 is connected to the stroke sensor 91 (connector 914) and the liquid level sensors 27 and 28 (connectors 270 and 280) via the harness 94. The ECU 90 is electrically connected to the hydraulic pressure sensors 92 and 93, and is connected to other control devices on the vehicle side via an in-vehicle network such as CAN. The ECU 90 opens and closes the solenoid valve 71 and the rotational speed of the motor 80 (based on information about the detected value of the sensor 91 and the like, information on the running state input from the vehicle side, and a built-in (stored in ROM) program) That is, the discharge amount of the pump 8 is controlled. Thereby, the wheel cylinder hydraulic pressure (hydraulic braking force) of each wheel FL-RR is controlled. The ECU 90 can execute various types of brake control by controlling the wheel cylinder hydraulic pressure. Brake control includes boost control to reduce driver's braking force, anti-lock brake control (ABS) to suppress wheel slip due to braking, traction control to suppress wheel drive slip, vehicle Brake control for motion control, automatic brake control such as preceding vehicle follow-up control, regenerative cooperative brake control, and the like. Vehicle motion control includes vehicle behavior stabilization control such as skidding prevention.

  The ECU 90 includes a reception unit 901, a calculation unit 902, and a drive unit 903. The receiving unit 901 receives the detection value of the sensor 91 and the like and information from the in-vehicle network. The calculation unit 902 performs a target wheel cylinder hydraulic pressure and other calculations based on information input from the reception unit 901. For example, based on the detection value of the stroke sensor 91, the displacement amount (pedal stroke) of the brake pedal 100 as a brake operation amount is detected. During boost control, based on the detected pedal stroke, a desired boost ratio, that is, the ideal relationship between the pedal stroke and the driver's required brake fluid pressure (vehicle deceleration required by the driver) is achieved. Set the target wheel cylinder hydraulic pressure. During regenerative cooperative brake control, for example, the sum of the regenerative braking force input from the control unit of the regenerative braking device of the vehicle and the hydraulic braking force corresponding to the target wheel cylinder hydraulic pressure satisfies the vehicle deceleration required by the driver. The target wheel cylinder hydraulic pressure is calculated. At the time of motion control, for example, the target wheel cylinder hydraulic pressure of each wheel FL to RR is calculated based on the detected vehicle motion state amount (lateral acceleration or the like) so as to realize a desired vehicle motion state. The calculation unit 902 calculates a command for driving the actuator (each electromagnetic valve 71 and the motor 80) so as to realize the target wheel cylinder hydraulic pressure, and outputs the command to the drive unit 903. The drive unit 903 supplies power to the actuator in accordance with a command signal from the calculation unit 902. Thus, the hydraulic unit 5, the hydraulic sensors 92 and 93, and the ECU 90 function as a hydraulic control device.

  In addition, although the calculating part 902 and the receiving part 901 are implement | achieved by the software in a microcomputer in embodiment, you may implement | achieve with an electronic circuit. The calculation means not only mathematical calculation but also general processing on software. The receiving unit 901 may be a microcomputer interface or software in the microcomputer. The drive unit 903 includes a PWM duty value calculation unit, an inverter, and the like. The command signal may relate to a current value, or may relate to a torque or a displacement amount. For the calculation unit 902, the target wheel cylinder hydraulic pressure that achieves a predetermined boost ratio may be set by calculation in addition to being set by a map in the microcomputer.

  The ECU 90 deactivates the pump 8 and controls the shut-off valve 71 in the opening direction. In this state, the fluid passage (supply fluid passage 11) connecting the chambers 47P and 47S of the master cylinder 4 and the wheel cylinder 101 is the wheel cylinder fluid by the master cylinder fluid pressure generated by using the pedal force of the brake pedal 100. Realizes pedal force braking (non-boosting control) that creates pressure. During the pedal effort braking, the ECU 90 controls the simulator-in valve 78 and the simulator-out valve 77 in the closing direction. As a result, the stroke simulator 6 is deactivated.

  The ECU 90 controls the hydraulic pressure of each wheel cylinder 101 by using the hydraulic pressure generated by the pump 8 in a state where the communication between the master cylinder 4 and the wheel cylinder 101 is cut off by controlling the second unit 1B (the driver Can be controlled individually (independent of the brake operation). The ECU 90 operates the pump 8 and controls the shut-off valve 71 in the closing direction. In this state, the fluid path (the suction fluid path 12, the discharge fluid path 13, etc.) connecting the fluid reservoir chamber 57 and the wheel cylinder 101 creates the wheel cylinder fluid pressure by the fluid pressure generated by the pump 8. A so-called brake-by-wire system is realized. The pump 8 sucks the brake fluid in the liquid reservoir chamber 57 through the suction liquid path 12, and discharges it to the discharge liquid path 13 (communication liquid paths 13P and 13S). The liquid reservoir chamber 57 is supplied with brake fluid from the reservoir tank 2 via the pipe 10R. The second unit 1B supplies the brake fluid boosted by the pump 8 to the wheel cylinder 101 via the wheel cylinder pipe 10W. For example, during boost control, the ECU 90 operates the pump 8 at a predetermined rotation speed, closes the shut-off valve 71 in the closing direction, the booster valve 72 in the opening direction, the communication valve 73 in the opening direction, and the closing direction in the pressure reducing valve 75. To control. The opening and closing of the pressure regulating valve 74 is controlled so that the fluid pressure in the discharge fluid passage 13 which is the fluid pressure upstream of the pressure regulating valve 74 becomes the target fluid pressure corresponding to the target wheel cylinder fluid pressure. Thereby, the target wheel cylinder hydraulic pressure is realized. The upstream hydraulic pressure is obtained by using any one or a plurality of detection values (for example, average values) of the hydraulic pressure sensors 92, 93P, 93S. In the boost control, the wheel cylinder hydraulic pressure higher than the master cylinder hydraulic pressure is created using the pump 8 as a hydraulic pressure source instead of the engine negative pressure booster. Thus, the brake operation force is assisted by generating a hydraulic braking force that is insufficient with the driver's brake operation force.

  During brake-by-wire, the ECU 90 controls the simulator-in valve 78 in the closing direction and the simulator-out valve 77 in the opening direction. Thereby, the stroke simulator 6 operates. In response to the driver's brake operation, brake fluid flows out of the master cylinder 4 and flows into the positive pressure chamber 607 of the stroke simulator 6. As a result, a pedal stroke is generated and a pedal reaction force is generated by the biasing force of the first and second springs 620 and 630. The brake fluid flowing out from the back pressure chamber 608 is supplied to the liquid reservoir chamber 57 through the back pressure liquid passage 17 (simulator out valve 77). Specifically, the third piston 61 is actuated (stroked) by the brake fluid flowing into the positive pressure chamber 607. When the first spring 620 is compressed by a predetermined amount or more in the y-axis direction according to the stroke of the third piston 61, the first elastic member 62A (the other end surface thereof) and the stopper 623 (the other end 629) contact each other, The first elastic member 62A is compressively elastically deformed. Thereby, the compressive deformation of the first spring 620 is restricted, and the impact at the time of restriction is alleviated. When the third piston 61 further strokes, the second spring 630 starts compressive elastic deformation. When the second spring 630 is compressed by a predetermined amount or more in the y-axis direction, the second elastic member 63A (the other end surface thereof) comes into contact with the third retainer 631 (the bottom portion 633), and the second elastic member 63A is compressed elastically. Deform. Thereby, the compressive deformation of the second spring 630 is restricted, and the impact at the time of restriction is alleviated. A first spring 620 and a second spring 630 having different spring coefficients are connected in series, and these are elastically deformed step by step. As a result, the characteristics of both the springs 620 and 630 as a whole (characteristics of changes in the spring coefficient with respect to the deformation amount) become nonlinear. For this reason, the pedal reaction force generated by the stroke simulator 6 according to the operation (pedal stroke) of the third piston 61 can be brought closer to a more desirable characteristic. The second spring 630 may start compressive deformation before the first spring 620 is restricted from compressive deformation. The spring coefficient and set load of the second spring 630 may be smaller than the spring coefficient and set load of the first spring 620. One or both of the first elastic member 62A and the second elastic member 63A may be omitted.

  The simulator-out valve 77 may be controlled in the closing direction after the start of the depression operation of the brake pedal 100 until the pump 8 can generate a sufficiently high wheel cylinder hydraulic pressure. As a result, the brake fluid flowing out from the back pressure chamber 608 is supplied to the supply liquid passage 11 through the back pressure supply liquid passage 18 (the bypass liquid passage 180 and the check valve 780) and supplied toward the wheel cylinder 101. . Thereby, the pressure | voltage rise responsiveness of wheel cylinder hydraulic pressure can be improved. When the pump 8 is in an operating state capable of generating a sufficiently high wheel cylinder hydraulic pressure, the brake outflow destination from the back pressure chamber 608 is transferred to the liquid storage chamber 57 by controlling the simulator out valve 77 in the opening direction. Can be switched. Note that the cross-sectional area of the back pressure supply liquid passage 18 may be increased by controlling the simulator-in valve 78 in the opening direction while the simulator-out valve 77 is controlled in the closing direction.

  If a power failure occurs while the stroke simulator 6 is operating, the simulator out valve 77 is closed. Due to the force of the springs 620 and 630, the third piston 61 strokes in the y-axis positive direction toward the initial position. When the replenishment hole 616 of the third piston 61 returns to the y-axis positive direction side with respect to the lip of the second seal member 65, the back pressure chamber 608 and the replenishment liquid passage 693 communicate with each other. As a result, the brake fluid is smoothly replenished from the liquid reservoir chamber 57 (reservoir tank 2) to the back pressure chamber 608 via the replenishment liquid passage 19. Note that the replenishment liquid passage 693 and the replenishment recess 603 may be omitted. In this case, the seal members 64 and 65 may be piston seals, squeeze packings (X rings) having an X-shaped cross section, or the like.

The pressure receiving area of the first piston 41P in the first chamber 47P is A1, the pressure receiving area of the second piston 41S in the second chamber 47S is A2, the pressure receiving area of the third piston 61 in the positive pressure chamber 607 is A3, and in the first chamber 47P. The pressure receiving area of the second piston 41S is A4. The hydraulic pressure in the first chamber 47P is P1, the hydraulic pressure in the second chamber 47S is P2, and the hydraulic pressure in the positive pressure chamber 607 is P3. In the present embodiment, since the diameters of the first to third pistons 41P, 41S, 61 (outer peripheral surfaces thereof) are substantially equal to each other, the formula (1) is established.
A1 = A2 = A3 = A4 (1)
Hereinafter, the sign of the force F follows the sign of the x-axis and y-axis directions. The force due to the fluid pressure P1 acting on the first piston 41P is Fp1, the force due to the fluid pressure P1 acting on the second piston 41S and the fluid pressure P2 is Fp2, and the force due to the fluid pressure P3 acting on the third piston 61 is Fp3. Equations (2), (3), and (4) hold.
Fp1 = P1 × A1… (2)
Fp2 = P2 × A2-P1 × A4 (3)
Fp3 = -P3 × A3… (4)
From the expressions (1) and (3), the expression (5) is established.
Fp2 = (P2-P1) × A2 (5)
When P1 = P3, Expression (6) is established from Expression (4).
Fp3 = -P1 × A3… (6)

The force of the spring 420P acting on the first piston 41P and the second piston 41S is fs1, the force of the spring 420S acting on the second piston 41S is fs2, the resultant force of the spring 420P and spring 420S acting on the first piston 41P is Fs1, The resultant force of the spring 420P and the spring 420S acting on the second piston 41S is Fs2, and the resultant force of the first spring 620 and the second spring 630 acting on the third piston 61 is Fs3. Equation (7) holds.
Fs2 = fs2-fs1… (7)
When the master cylinder 4 is not operating (initial state), fs1 (set load of the spring 420P) is fset1, fs2 (set load of the spring 420S) is fset2, Fs1 is Fset1, and Fs2 is Fset2. Let Fs3 be Fset3 when the stroke simulator 6 is not in operation (initial state). If the resultant force of Fp1 and Fs1 acting on the first piston 41P is F1, the resultant force of Fp2 and Fs2 acting on the second piston 41S is F2, and the resultant force of Fp3 and Fs3 acting on the third piston 61 is F3, the equation (8 ) (9) (10) holds.
F1 = Fp1 + Fs1… (8)
F2 = Fp2 + Fs2… (9)
F3 = Fp3 + Fs3… (10)

The specifications of each part of the master cylinder 4 and the stroke simulator 6 are set so as to satisfy the following condition (A). That is, when the brake pedal 100 is depressed,
(A) When the second piston 41S starts operation (stroke) from a stopped state, the first piston 41P and the third piston 61 are in a stroke state. In particular,
(A1) The third piston 61 starts the stroke after the first piston 41P starts the stroke, and the second piston 41S starts the stroke after the third piston 61 starts the stroke. Or
(A2) After the first piston 41P starts the stroke, the third piston 61 and the second piston 41S start the stroke. Or
(A3) The second piston 41S starts the stroke after the first piston 41P and the third piston 61 start the stroke.

  In the brake system described above, the pressure-increasing valve 72 is normally linearly controlled and switched to pulse control according to the conditions shown in the first and second embodiments, so that the same effects as those in the first and second embodiments can be obtained.

[Technical ideas that can be grasped from Examples]
As mentioned above, although the form for implementing this invention was demonstrated based on the Example, the concrete structure of this invention is not limited to the structure shown in the Example, and is the range which does not deviate from the summary of invention. Any design changes are included in the present invention. Hereinafter, technical ideas that can be grasped from the embodiments will be described below.
(1) The brake control device of the present technical idea is, in one aspect thereof,
A connecting fluid path connected to a wheel cylinder part capable of applying a braking force to the wheel part of the vehicle according to the brake fluid pressure;
A pressure increasing valve portion in the connection liquid path;
In response to an input signal based on the acquired state of the ground road surface of the wheel portion, linear control for controlling a current to be supplied to the pressure increasing valve portion and pulse control for controlling a time for opening the pressure increasing valve portion. A control unit to switch,
Equipped with.
(2) In a more preferred embodiment, in the above embodiment,
The control unit switches to the pulse control when the friction coefficient of the ground road surface is high compared to the low friction coefficient.
(3) In another preferred embodiment, in any of the above embodiments,
The wheel portion includes a first wheel portion that is one of the left and right wheels of the vehicle, and a second wheel portion that is the other of the left and right wheels,
The control unit switches to the pulse control when the friction coefficient of the grounded road surface is a split road surface in which the second wheel unit is lower than the first wheel unit.
(4) In still another preferred embodiment, in any of the above embodiments,
The first wheel portion includes a first front wheel that is a front wheel of the vehicle, and a first rear wheel that is a rear wheel of the vehicle,
The second wheel portion includes a second front wheel that is a front wheel of the vehicle, and a second rear wheel that is a rear wheel of the vehicle,
The pressure increasing valve section includes a first pressure increasing valve corresponding to the first front wheel, a second pressure increasing valve corresponding to the first rear wheel, a third pressure increasing valve corresponding to the second front wheel, and the second rear pressure valve. A fourth pressure increasing valve corresponding to the wheel,
The control unit switches only the second pressure increasing valve to the pulse control.
(5) In still another preferred embodiment, in any of the above embodiments,
The wheel portion includes a first wheel portion that is one of the left and right wheels of the vehicle, and a second wheel portion that is the other of the left and right wheels,
The first wheel portion includes a first front wheel that is a front wheel of the vehicle, and a first rear wheel that is a rear wheel of the vehicle,
The second wheel portion includes a second front wheel that is a front wheel of the vehicle, and a second rear wheel that is a rear wheel of the vehicle,
The pressure increasing valve section includes a first pressure increasing valve corresponding to the first front wheel, a second pressure increasing valve corresponding to the first rear wheel, a third pressure increasing valve corresponding to the second front wheel, and the second rear pressure valve. A fourth pressure increasing valve corresponding to the wheel,
The control unit switches at least one of the first pressure increasing valve, the second pressure increasing valve, the third pressure increasing valve, and the fourth pressure increasing valve.
(6) In still another preferred embodiment, in any of the above embodiments,
The control unit switches to the pulse control during the ABS control.
(7) In still another preferred embodiment, in any of the above embodiments,
The control unit switches to the pulse control when the deceleration of the vehicle is greater than a set threshold value.
(8) In still another preferred embodiment, in any of the above embodiments,
The wheel portion includes a first wheel portion that is one of the left and right wheels of the vehicle, and a second wheel portion that is the other of the left and right wheels,
The control unit switches to the pulse control when the braking force generated in the first wheel portion is larger than a value obtained by adding a predetermined value to the braking force generated in the second wheel portion.

(9) From another point of view, the brake control method of the present technical idea is, in one aspect thereof,
A first step of acquiring information based on a state of a ground road surface of a wheel portion of the vehicle;
A linear control for controlling a current applied to a pressure increasing valve portion in a connecting fluid path connected to a wheel cylinder portion capable of applying a braking force to the wheel portion; and a pulse control for controlling a time for opening the pressure increasing valve portion. , A second step of switching according to the state of the ground road surface of the wheel portion acquired by the first step,
Equipped with.
(10) In a more preferred embodiment, in the above embodiment,
In the second step, when the friction coefficient of the ground contact surface is low, the control is switched to the pulse control when the friction coefficient is high.
(11) In still another preferred embodiment, in any of the above embodiments,
In the second step,
When the second wheel portion, which is the other of the left and right wheels, is a split road surface having a lower friction coefficient of the ground road surface than the first wheel portion which is one of the left and right wheels of the wheel portions, the control is switched to the pulse control. .
(12) In still another preferred embodiment, in any of the above embodiments,
In the second step,
Of the first wheel part, the front wheel is the first front wheel, the rear wheel is the first rear wheel, the second wheel part is the front wheel as the second front wheel, the rear wheel is the second rear wheel, The pressure increasing valve corresponding to the first front wheel is a first pressure increasing valve, the pressure increasing valve corresponding to the first rear wheel is a second pressure increasing valve, the pressure increasing valve corresponding to the second front wheel is a third pressure increasing valve, and the second rear pressure valve. When the pressure increasing valve corresponding to the wheel is the fourth pressure increasing valve,
Only the second pressure increasing valve is switched to the pulse control.
(13) In still another preferred embodiment, in any of the above embodiments,
In the second step,
Of the first wheel part, the front wheel is the first front wheel, the rear wheel is the first rear wheel, the second wheel part is the front wheel as the second front wheel, the rear wheel is the second rear wheel, The pressure increasing valve corresponding to the first front wheel is a first pressure increasing valve, the pressure increasing valve corresponding to the first rear wheel is a second pressure increasing valve, the pressure increasing valve corresponding to the second front wheel is a third pressure increasing valve, and the second rear pressure valve. When the pressure increasing valve corresponding to the wheel is the fourth pressure increasing valve,
At least one of the first pressure increasing valve, the second pressure increasing valve, the third pressure increasing valve, and the fourth pressure increasing valve is switched.
(14) In still another preferred embodiment, in any of the above embodiments,
In the second step, the pulse control is switched to the ABS control.
(15) In still another preferred embodiment, in any of the above embodiments,
In the second step, when the deceleration of the vehicle is larger than a set threshold value, the control is switched to the pulse control.
(16) In still another preferred embodiment, in any of the above embodiments,
In the second step,
When the braking force generated in the first wheel part which is one of the left and right wheels among the wheel parts is larger than the value obtained by adding a predetermined value to the braking force generated in the second wheel part which is the other of the left and right wheels, the pulse Switch to control.

Z1 pipeline
Z2 pipe (connection liquid path)
Z3 Gate-out valve
Z4 Master cylinder hydraulic pressure sensor
Z6 Solenoid In Valve
Z13 Pressure regulating reservoir
Z16 Check valve
Z21 solenoid
Z22 Disc
BCU Brake control unit (control unit)
ZBP brake pedal
ZM / C master cylinder
P pump
W / C wheel cylinder
72 Booster valve

Claims (9)

A connecting fluid path connected to a wheel cylinder part capable of applying a braking force to the wheel part of the vehicle according to the brake fluid pressure;
A pressure increasing valve portion in the connection liquid path;
In response to an input signal based on the acquired state of the ground road surface of the wheel portion, linear control for controlling a current to be supplied to the pressure increasing valve portion and pulse control for controlling a time for opening the pressure increasing valve portion. A control unit to switch,
A brake control device comprising: The brake control device according to claim 1, wherein
The control unit is configured to switch to the pulse control when the friction coefficient of the ground contact surface is high compared to a low friction coefficient. The brake control device according to claim 1, wherein
The wheel portion includes a first wheel portion that is one of the left and right wheels of the vehicle, and a second wheel portion that is the other of the left and right wheels,
The brake control device according to claim 1, wherein the control unit switches to the pulse control when the friction coefficient of the ground contact surface is a split road surface that is lower in the second wheel portion than in the first wheel portion. The brake control device according to claim 3,
The first wheel portion includes a first front wheel that is a front wheel of the vehicle, and a first rear wheel that is a rear wheel of the vehicle,
The second wheel portion includes a second front wheel that is a front wheel of the vehicle, and a second rear wheel that is a rear wheel of the vehicle,
The pressure increasing valve section includes a first pressure increasing valve corresponding to the first front wheel, a second pressure increasing valve corresponding to the first rear wheel, a third pressure increasing valve corresponding to the second front wheel, and the second rear pressure valve. A fourth pressure increasing valve corresponding to the wheel,
The brake control device, wherein the control unit switches only the second pressure increasing valve to the pulse control. The brake control device according to claim 1, wherein
The wheel portion includes a first wheel portion that is one of the left and right wheels of the vehicle, and a second wheel portion that is the other of the left and right wheels,
The first wheel portion includes a first front wheel that is a front wheel of the vehicle, and a first rear wheel that is a rear wheel of the vehicle,
The second wheel portion includes a second front wheel that is a front wheel of the vehicle, and a second rear wheel that is a rear wheel of the vehicle,
The pressure increasing valve section includes a first pressure increasing valve corresponding to the first front wheel, a second pressure increasing valve corresponding to the first rear wheel, a third pressure increasing valve corresponding to the second front wheel, and the second rear pressure valve. A fourth pressure increasing valve corresponding to the wheel,
The brake control device, wherein the control unit switches at least one of the first pressure increasing valve, the second pressure increasing valve, the third pressure increasing valve, and the fourth pressure increasing valve. The brake control device according to claim 1, wherein
The brake control device, wherein the control unit switches to the pulse control in the ABS control. The brake control device according to claim 6,
The control unit switches to the pulse control when the deceleration of the vehicle is larger than a set threshold value. The brake control device according to claim 6,
The wheel portion includes a first wheel portion that is one of the left and right wheels of the vehicle, and a second wheel portion that is the other of the left and right wheels,
The control unit switches to the pulse control when the braking force generated in the first wheel portion is larger than a value obtained by adding a predetermined value to the braking force generated in the second wheel portion. . A first step of acquiring information based on a state of a ground road surface of a wheel portion of the vehicle;
A linear control for controlling a current applied to a pressure increasing valve portion in a connecting fluid path connected to a wheel cylinder portion capable of applying a braking force to the wheel portion; and a pulse control for controlling a time for opening the pressure increasing valve portion. , A second step of switching according to the state of the ground road surface of the wheel portion acquired by the first step,
A brake control method comprising:

Images