JP6812313B2 - Brake control device and brake control method - Google Patents

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 boosting valve is switched from linear control to pulse control to increase the brake fluid pressure boosting speed and suppress the occurrence of insufficient boosting. The technology is disclosed.

JP-A-2006-103438

However, in the above-mentioned Patent Document 1, even if the insufficient deceleration can be suppressed, there is a possibility that it becomes difficult to secure the stability of the vehicle behavior at the time of braking due to the unexpected overpressure.
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, in the present invention, a pressure boosting valve in a connecting liquid passage connected to a wheel cylinder portion capable of acquiring information based on the state of the ground contact road surface of the wheel portion of the vehicle and applying a braking force to the wheel portion. It was decided to switch between linear control for controlling the current energizing the part and pulse control for controlling the time for opening the booster valve part according to the acquired state of the ground contact road surface of the wheel part.

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

It is a circuit block diagram of the brake control device of Example 1. FIG. It is a schematic diagram which shows the structure of the solenoid-in-valve of Example 1. FIG. It is an enlarged view of the main part of the solenoid-in-valve of Example 1. It is a flowchart which shows the switching process of linear control and pulse control of Example 1. It is a time chart which shows the ABS control in the high μ road of Example 1. It is a time chart which shows the ABS control in the split μ path of Example 1. FIG. It is a time chart which shows the ABS control in the split μ path of Example 2. It is a figure which shows the schematic structure of the brake system of Example 3. It is a figure which shows the schematic structure of the 1st unit of Example 3.

[Example 1]
[Circuit configuration]
FIG. 1 is a circuit configuration diagram of the brake control device of the first embodiment.
The hydraulic pressure control unit HU adjusts the braking force applied to each wheel of the vehicle, and based on the command from the brake control unit (control unit) BCU, the left rear wheel wheel cylinder W / C (RL), right Increases or decreases or holds the hydraulic pressure of the front wheel wheel cylinder W / C (FR), left front wheel wheel cylinder W / C (FL), and right rear wheel wheel cylinder W / C (RR).
The hydraulic pressure 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 the X piping, even if one piping system fails, the other piping system can be used to generate half the braking force in the normal state. In addition, P attached to the end of the code of each part shown in FIG. 1 indicates P system, S indicates S system, and RL, FR, FL, RR indicate left rear wheel, right front wheel, left front wheel, right rear. Indicates that it corresponds to a ring. In the following description, when the P, S system or each wheel is not distinguished, the description of P, S or RL, FR, FL, RR is omitted.

The hydraulic pressure control unit HU of 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, for the closed hydraulic circuit, 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 is.
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) of the left rear wheel RL and the wheel cylinder W / C (FR) of the right front wheel FR are connected to the S system, and the wheel cylinder W / C (FR) of 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 S system. The pumps PP and PS are driven by one motor M. In the first embodiment, the pumps PP and PS are used as plunger pumps.

The master cylinder ZM / C and the wheel cylinder W / C are connected by the pipe line 1 and the pipe line 2. The pipeline Z2S branches into the pipelines Z2RL and 2FR, the pipeline Z2RL is connected to the wheel cylinder W / C (RL), and the pipeline Z2FR is connected to the wheel cylinder W / C (FR). The pipeline Z2P branches into pipelines Z2FL and 2RR, the pipeline Z2FL is connected to the wheel cylinder W / C (FL), and the pipeline Z2RR is connected to the wheel cylinder W / C (RR).
A gate-out valve Z3, which is a normally open type proportional control valve, is provided on the pipeline Z1. A master cylinder hydraulic pressure sensor Z4 is provided at a position on the master cylinder side of the gate-out valve Z3P of the P system pipeline Z1P. On the pipeline Z1, a pipeline Z4 is provided in parallel with the gate-out valve Z3. A check valve Z5 is provided on the pipeline Z4. The check valve Z5 allows the flow of brake fluid from the master cylinder ZM / C to the wheel cylinder W / C and prohibits the flow in the opposite direction.
A solenoid-in valve Z6, which is a normally open type proportional control valve corresponding to each wheel cylinder W / C, is provided on the pipeline Z2. A pipeline Z7 is provided in parallel with the solenoid-in valve Z6 on the pipeline Z2. A check valve Z8 is provided on the pipeline 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 pipeline Z2 are connected by the pipeline Z9. A discharge valve Z10 is provided on the pipeline Z9. The discharge valve Z10 allows the flow of brake fluid from the pump P toward the pipeline Z2 and prohibits the flow in the opposite direction.
The position on the master cylinder side of the gate-out valve Z3 of the pipeline Z1 and the suction side of the pump P are connected by the pipeline Z11 and the pipeline Z12. A pressure regulating reservoir Z13 is provided between the pipeline Z11 and the pipeline Z12.
The position on the wheel cylinder side of the solenoid-in valve Z6 of the pipeline Z2 and the pressure adjusting reservoir Z13 are connected by the pipeline Z14. The pipeline Z14S branches into pipelines Z14RL and Z14FR, and the pipeline Z14P branches into pipelines 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 pipeline Z14.
The pressure regulating reservoir Z13 includes a pressure-sensitive check valve Z16. The check valve Z16 prevents the high pressure from being applied to the suction side of the pump P by prohibiting the inflow of the brake fluid into the reservoir when the pressure in the pipeline Z11 exceeds a predetermined pressure. To do. When the pump P operates and the pressure in the pipeline Z12 becomes low, the check valve Z16 opens regardless of the pressure in the pipeline Z11 and allows the brake fluid to flow into the reservoir. To do.

The brake control unit BCU includes the wheel speed detected by the wheel speed sensors Sfl, Sfr, Srl, and Srr (hereinafter collectively referred to as the wheel speed sensor Sx) provided on each wheel, and the yaw rate and front / rear of the vehicle. 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 has an ABS control unit that performs anti-lock braking control (hereinafter referred to as ABS control) that avoids wheel lock when it detects a wheel lock tendency, and the target vehicle behavior and actual behavior based on the steering angle. Friction between the road surface and the VDC control unit that performs vehicle behavior control (hereinafter referred to as VDC control) that brings the vehicle behavior closer to the target vehicle behavior by applying a yaw moment to the vehicle by braking hydraulic pressure when the vehicle behavior deviates. It has a road surface μ estimation unit that estimates the road surface μ, which is a coefficient. The road surface μ estimation unit estimates the road surface μ from the equation of motion of the wheels.
(Equation 1)
I × (dω / dt) ＝ (μ × W × R) -τ: Wheel equation of motion
I: Wheel inertia
dω / dt: Wheel acceleration τ: Brake torque (calculated from wheel cylinder pressure and brake pad friction coefficient, etc.)
μ: Road surface μ
W: Wheel load
R: Depending on the 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 opening time of the master cylinder hydraulic pressure sensor Z4 and the solenoid in valve Z6 and solenoid out valve Z15. The road surface μ is estimated by a method of estimating from the relationship between the steering torque and the road surface reaction force in the steering device, or by calculating the estimated deceleration 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 depressurization start threshold value and a pressure increase start threshold value. When the wheel speed falls below the decompression start threshold value, the solenoid in valve Z6 is closed and then the solenoid out valve Z15 is opened to foil. The cylinder pressure is reduced, the wheel cylinder pressure is maintained when the pressure is between the depressurization 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. To increase the pressure. When it is determined that the road surface μ of the right wheel and the left wheel is a different split μ road, the wheel cylinder pressure on the high μ road side is about the wheel cylinder pressure when ABS control is performed on the low μ road side. 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 from each other by a predetermined value or more, the gate-out valve 3 is closed, the pump P is operated, and the solenoid-in valve 6 of the desired wheel is opened to open the wheel cylinder. Increase the pressure.

[Solenoid in valve]
FIG. 2 is a schematic view showing the configuration of the solenoid-in valve of the first embodiment.
The solenoid-in valve Z6 includes a solenoid Z21 that generates an electromagnetic attraction force, a valve body Z22 that operates in response to this electromagnetic attraction force, and a coil spring Z23 that urges the valve body Z22 in the valve opening direction (upper in FIG. 2). It is composed of a valve body Z24 on the pipeline Z2, to which the pipeline Z2a on the master cylinder side and the pipeline Z2b on the wheel cylinder side are connected to the solenoid-in valve Z6. When the valve body Z22 moves downward in FIG. 2, the tip portion of the valve body Z22 is seated on the seat Z26 formed on the valve body Z24, so that the pipeline Z2a and the conduit Z2b are closed. On the other hand, when the valve body Z22 moves upward in FIG. 2, the tip portion of the valve body Z22 separates from the seat Z26, so that the pipeline Z2a and the pipeline Z2b are opened. That is, the communication state (differential pressure) between the pipeline Z2a and the pipeline 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 of the first embodiment.
In the valve body Z22, the force Fa corresponding to the differential pressure between the pressure on the upstream side (corresponding to the master cylinder hydraulic pressure) and the pressure on the downstream side (corresponding to the wheel cylinder hydraulic pressure) of the solenoid-in valve Z6 is applied to the upper part in FIG. A force Fb corresponding to the electromagnetic attraction force of the solenoid Z21 acts in the lower part of FIG. 3, and a force Fc due to the urging force of the coil spring Z23 acts in the upper part of FIG. By controlling the current that energizes the solenoid Z21, the differential pressure can be controlled to a desired value. That is, the urging force of the coil spring Z23 is uniquely determined according to the position of the valve body Z22. Therefore, if the current value is controlled to a predetermined value, the force due to the above differential pressure that finally balances the electromagnetic attraction force corresponding to this current value and the urging force of the coil spring Z23 acts on the valve body Z22. The valve body Z22 strokes to adjust the flow rate through the gate-out valve Z3. Hereinafter, this is referred to as linear control of the solenoid-in valve Z6. For linear control, the current that energizes the solenoid Z21 is pulsed from 0 amperes to the current that closes the solenoid Z21, and the valve body Z22 strokes according to the valve opening time to adjust the flow rate flowing through the solenoid-in valve Z6. It is possible. Hereinafter, this is referred to as pulse control of the solenoid-in valve Z6.

(Issues of linear control)
The feature of linear control makes it possible to fine-tune the flow rate. Therefore, the 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 and downstream differential pressure of the solenoid-in valve Z6 by linear control, the flow rate is higher or lower than the target flow rate due to the hydraulic pressure fluctuation of the master cylinder and the individual difference of the solenoid-in valve Z6. May be. If a flow rate higher than the target flow rate is generated, the amount of liquid flowing to the wheel cylinder side 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 wheel slip to the small slip by ABS control, the braking force may be reduced and the stopping distance may be extended.

Further, when braking on a road surface (hereinafter referred to as a split μ road) having a different road surface friction coefficient (hereinafter referred to as a road surface μ) on the left and right sides of the vehicle, a high braking force on the road surface μ is obtained due to excessive pressure boosting. It may be stronger than the braking force of a 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 lead to 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, so that the pressure boosting is too small. In ABS control when the pressure increase is too small, the hydraulic pressure is lower than the target hydraulic pressure, so the braking force is reduced and the stopping distance may be extended. Therefore, it was decided to switch the control method of the solenoid-in valve Z6 between linear control and pulse control according to the driving situation.

(Switching process between linear control and pulse control)
Next, the switching process between linear control and pulse control will be described. FIG. 4 is a flowchart showing the switching process of linear control and pulse control of the first embodiment.
In step S1, the estimated deceleration is calculated, it is determined whether or not the estimated deceleration is larger than the preset high μ pulse control execution judgment threshold, and if it is larger than the high μ pulse control execution judgment threshold, step S4 Proceed to, otherwise proceed to step S2. Here, the estimated deceleration may be calculated based on, for example, the amount of change in the 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. Further, the high μ time pulse control execution judgment threshold is a value that can be judged as a high μ path, and if a deceleration larger than the high μ time pulse control execution judgment threshold value can be obtained, it is a high μ path and a high μ time pulse. If a deceleration equal to or lower than the control execution determination threshold value is obtained, it is determined that the path is low μ.

In step S2, it is determined whether or not the road is a split μ road, and if it is determined to be a split μ road, the process proceeds to step S4, and if not, the process proceeds to step S3. In determining whether or not the road is a split μ road, it is determined whether or not the estimated braking force for the left wheel and the estimated braking force for the right wheel deviate 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 or not any of the above is satisfied.
The estimated braking force is a value obtained by multiplying the brake torque τ included in the wheel equation of motion shown in (Equation 1) by the tire radius R. The predetermined value is a value representing the braking force difference that occurs between the low μ road and the high μ road, and when the estimated braking force difference between the left and right wheels deviates by a predetermined value or more, the vehicle tends to spin. Shown.
In step S3, the control method of the solenoid-in valve Z6 is set to linear control.
In step S4, the control method of the solenoid-in valve Z6 is set to pulse control.

FIG. 5 is a time chart showing ABS control in the high μ road of Example 1. At time t1, ABS control is started by sudden braking by the driver, and the estimated deceleration is a value larger than the pulse control execution determination threshold value at high μ, so that the pulse control execution determination flag is turned ON. Therefore, a target hydraulic pressure for boosting, holding, and depressurizing is set for each wheel based on ABS control, and pulse control is performed so as to achieve this target hydraulic pressure. That is, when it is determined that the road is high μ, if linear control is selected, the amount of decompression becomes excessive when the pressure is reduced after the pressure is increased, and the stopping distance may be extended as the braking force is reduced. On the other hand, when pulse control is selected, even if an excessive flow rate occurs, the state of excessive flow rate does not continuously occur because the control is performed by the valve opening time. Therefore, it is possible to prevent the amount of decompression from becoming excessive at the time of decompression after the pressure increase, and to secure the braking force.

FIG. 6 is a time chart showing ABS control in the split μ path of Example 1. At time t1, when ABS control is started due to sudden braking by the driver, linear control is selected because the estimated deceleration is smaller than the high μ pulse control execution determination threshold. At this point, a large difference has not been detected in the road surface μ installed by the left wheel and the right wheel. After that, at time t2, when the road surface μ on the left side is judged to be a high μ road, and the split μ road is judged, the target hydraulic pressure of the left wheel on the high μ road side is the target liquid of the right wheel on the low μ road side. A target hydraulic pressure that is approximately 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 decompression start threshold value, it is not necessary to perform ABS control that repeats decompression, holding, and pressure increase. However, in order to avoid an unnecessary yaw moment due to the difference in braking force between the left side and the right side, it is avoided that a large braking force is generated on the high μ road side. At this time, if the linear control is continued and the flow rate becomes excessive, a large braking force is generated on the high μ road side, and the vehicle behavior may become unstable. Therefore, the linear control is switched to the pulse control. 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 Example 1, the following effects can be obtained.
(1) Pipeline Z2, which is a connecting liquidway connected to a wheel cylinder W / C that can apply braking force to the wheels of the vehicle according to the brake hydraulic pressure, and solenoid-in valve Z6 (pressure boosting valve) in the pipeline Z2. Part), linear control that controls the current that energizes the solenoid-in valve Z6, pulse control that controls the time to open the solenoid-in valve Z6, and an input signal based on the state of the ground contact road surface of the wheel part that has been acquired. It is equipped with a brake control unit BCU that switches according to the situation.
Therefore, it is possible to suppress the instability of the vehicle behavior during braking.
(2) The brake control unit BCU switches to pulse control when the friction coefficient of the ground contact surface is higher than when it is low.
Therefore, it is possible to reduce the extension of the stopping distance and the lack of braking force caused by the over-decompression that occurs after the over-pressure on the high μ road.
(3) The wheel portion includes a first wheel portion which is one of the left and right wheels of the vehicle and a second wheel portion which is the other of the left and right wheels, and the brake control unit BCU has a first friction coefficient on the ground contact surface. If the split μ path is lower on the second wheel than on the wheel, switch to pulse control.
Therefore, the spin tendency due to the high μ side overpressure in the split μ path can be reduced.

(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) When the deceleration of the vehicle is larger than the set threshold value for performing pulse control at high μ, the brake control unit BCU switches to pulse control.
Therefore, it is possible to reduce the extension of the stopping distance and the lack of braking force caused by the over-decompression that occurs after the over-pressure on the high μ road.
(6) The wheel portion includes a first wheel portion which is one of the left and right wheels of the vehicle and a second wheel portion which is the other of the left and right wheels, and the brake control unit BCU is a control generated in the first wheel portion. When the power is larger than the value obtained by adding a predetermined value to the braking force generated in the second wheel portion, the pulse control is switched.
Therefore, the spin tendency due to the high μ side overpressure in the split μ path can be reduced.

(Example 2)
Next, Example 2 will be described. Since the basic configuration is the same as that of the first embodiment, only the differences will be described. FIG. 7 is a time chart showing ABS control in the split μ path of Example 2. In the first embodiment, the control of the solenoid-in valve Z6 in all wheels was changed from linear control to pulse control during deceleration on the split μ path. On the other hand, in the second embodiment, when decelerating 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 secure 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 wheels decreases. Therefore, the friction circle of the rear wheels tends to be small, and the cornering force tends to decrease significantly when the rear wheels are over-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, in the case of the split μ road, by switching from the linear control to the pulse control only for the rear wheels on the high μ road side, it is possible to suppress the deterioration of the sound vibration performance while ensuring the vehicle stability. did.

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

(Example 3)
Next, Example 3 will be described. In the first embodiment, an example applied to the brake control device of the closed hydraulic circuit has been described. On the other hand, in Example 3, it was applied to the brake control device of the brake-by-wire system. FIG. 8 is a diagram showing a schematic configuration of the brake system of the third embodiment, and FIG. 9 is a diagram showing a schematic configuration of the first unit of the third embodiment. The brake system 1 of the third embodiment includes a vehicle having only an internal combustion engine (engine) as a prime mover for driving wheels, a hybrid vehicle having an electric motor (generator) in addition to the engine, and an electric motor. It is a hydraulic braking system that can be mounted on electric vehicles, etc. equipped with only the brake pedal 100 and the wheel cylinder 101 of the wheels (left front wheel FL, right front wheel FR, left rear wheel RL, and right rear wheel RR). Placed in between. The brake system 1 supplies a brake fluid as a working fluid to the wheel cylinder 101 to generate a hydraulic pressure (brake hydraulic pressure) in the wheel cylinder 101. The wheel cylinder 101 applies frictional braking force (hydraulic braking force) to the wheels 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 between the member corresponding to the first system (primary system) and the member corresponding to the second system (secondary system), the subscripts P and S are added to the end of each code. Members corresponding to each wheel FL to RR are appropriately distinguished by adding subscripts a to d at the end of their codes.

As shown in FIG. 8, the brake system 1 has 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 driver's 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 have a negative pressure booster. Here, the negative pressure booster is a device that doubles the brake operating force of the driver by utilizing the negative pressure generated by the engine of the vehicle or the negative pressure pump provided separately. The second unit 1B integrally includes a hydraulic pressure unit 5, a stroke simulator 6, hydraulic pressure sensors 92, 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 have a master cylinder pipe 10M (first pipe 10MP, second pipe 10MS) and a suction pipe 10R. The second unit 1B and the wheel cylinder 101 of each wheel are connected to each other by the wheel cylinder pipe 10W.

The reservoir tank 2 is a brake fluid source for storing the 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 wall 21 to 23 extends from the bottom 20 of the reservoir tank 2 to a predetermined height, and divides the side of the bottom 20 inside the reservoir tank 2 into a plurality of chambers. The first chamber 24P 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. The second room 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. On the outer surface of the bottom 20, connectors 270,280 of the liquid level sensors 27,28 are installed. On the side surface of the reservoir tank 2, there is a port 29 communicating with the third chamber 26. 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 collar portion 30. The collar 30 includes a tapered surface 300.

The master cylinder 4 is a first hydraulic pressure source that operates in response to the operation of the brake pedal 100 by the driver and can supply the hydraulic hydraulic pressure to the wheel cylinder 101. The master cylinder 4 has a first cylinder 40, a piston 41, a spring unit 42, and seal members 43 and 44. The first cylinder 40 accommodates the piston 41 and the like. The reservoir tank 2 is installed on the upper side of the first cylinder 40 in the vertical direction. 8 and 9 show a cross section passing through the axis of the master cylinder 4. For convenience of explanation, the x-axis is provided in the moving direction (axis direction) of the piston 41, and the side on which the piston 41 moves in response to the stepping operation of the brake pedal 100 is negative. As shown in FIG. 9, the inner circumference of the first cylinder 40 has a large diameter portion 401 and a small diameter portion 402. These sections 401, 402 are cylindrical and extend in the x-axis direction on substantially the same axis (within manufacturing error) from each other. The large diameter portion 401 is located at the end of the first cylinder 40 on the positive side of the x-axis. The diameter of the end of the large diameter portion 401 on the positive side of the x-axis gradually decreases toward the positive side of the x-axis. As a result, the tapered surface 403 is formed. A hole 404 opens in the center of this surface 403. The hole 404 extends on the axis in the x-axis direction 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 brake pedal 100 side of the collar portion 30) of the push rod 3 and smaller than the diameter of the collar portion 30. The portion 31 of the push rod 3 fits into the hole 404. At the end of the large diameter portion 401 on the negative side of the x-axis, a rod-shaped guide member 910 is installed at the step portion between the large diameter portion 401 and the small diameter portion 402. The guide member 910 extends in the x-axis direction inside the large diameter portion 401.

The small diameter portion 402 is adjacent to the large diameter portion 401 on the negative side of the x-axis. 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 supply recess 405P and the like of the first system are on the x-axis positive direction side of the small diameter portion 402, and are adjacent to the x-axis negative direction side with respect to the large diameter portion 401. The replenishment recess 405S and the like of the second system are on the x-axis negative direction side of the small diameter portion 402, and are adjacent to the replenishment recess 405P and the like of the first system on the x-axis negative direction side. These recesses 405, 406 and grooves 407, 408 are annular surfaces extending in the circumferential direction (hereinafter, circumferential direction) of the axis. The replenishment 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 the supply recess 405 in the x-axis direction. The first groove 407 is on the x-axis positive direction side of the replenishment recess 405, and the second groove 408 is on the x-axis negative direction side of the replenishment recess 405. The first seal member 43 is installed in the first groove 407, and the second seal member 44 is installed in the second groove 408. The sealing members 43 and 44 are annular 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 negative side of the x-axis. The first cylinder 40 has a supply liquid passage 45 and a supply liquid passage 46 for each of the first and second systems. These liquid passages extend inside the first cylinder 40 in the radial direction (hereinafter, radial direction) with respect to the axis and open to the small diameter portion 402 and open to the outer surface 400 of the first cylinder 40. The supply liquid passage 45 opens in the supply recess 405, and the supply liquid passage 46 opens in the supply recess 406. On the outer surface 400 of the first cylinder 40, the opening of the replenishment passage 45P of the first system is connected to the opening at the bottom 20 of the first chamber 24P of the reservoir tank 2, and the opening of the replenishment passage 45S of the second system is the reservoir. It connects to the opening at 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 movably housed inside the first cylinder 40 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 the push rod 3. The second piston 41S is movably housed inside the first cylinder 40 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 negative side of the x-axis with respect to the first piston 41P. The second piston 41S is a free piston type and is interlocked with the first piston 41P. The outer circumference 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) are substantially equal to each other. The lips of the sealing members 43 and 44 are in contact with the outer peripheral surface of the piston 41.

On the inner peripheral side of the piston 41, there are bottomed cylindrical recesses 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 recesses 411 and 412 are substantially equal. At the bottom of both recesses 411,412, there is a wall 413 that separates both recesses 411,412. The wall 413P of the first piston 41P has a hemispherical recess 414 on the side of the first recess 411. The other end of the push rod 3 includes a hemispherical convex portion 32. The convex portion fits into the concave portion 414 and abuts on the bottom surface of the concave portion 414. There is a supply hole 415 on the peripheral wall of the second recess 412 in the piston 41. The supply hole 415 extends radially with respect to the axis of the piston 41, penetrates the peripheral wall, and opens to the inside (second recess 412) and the outside (outer surface 410 of the piston 41) of the peripheral wall. A plurality (for example, four) of the supply holes 415 are arranged at substantially equal intervals in the direction around the axis of the piston 41 on the opening side of the second recess 412 with respect to the bottom side.

Inside the first cylinder 40, the first chamber 47P is partitioned by the first piston 41P and the second piston 41S, and the second piston 41S is on the opposite side in the axial direction (x-axis negative direction side) with respect to the first chamber 47P. 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) of the first chamber 47P in the axial direction. The first chamber 47P is on the negative side of the x-axis with respect to the second seal member 44P on the outer peripheral surface of the second seal member 44P and the first piston 41P, the second recess 412P of the first piston 41P, the first seal member 43S, and the first. The x-axis positive direction side of the outer peripheral surface of the two pistons 41S from the first seal member 43S, the first recess 411S of the second piston 41S, and the second seal member 44P and the first seal member in the small diameter portion 402 of the first cylinder 40. It is defined by the space between 43S (mainly the supply recess 406P). The second chamber 47S has a small diameter of the second sealing member 44S, the second concave portion 412S of the second piston 41S, and the small diameter of the first cylinder 40 on the outer peripheral surface of the second piston 41S on the negative side of the x-axis with respect to the second sealing member 44S. It is defined by the x-axis negative direction side (including the supply recess 406S) of the second seal member 44S in the portion 402. The third chamber 48 is located on the x-axis positive direction side of the outer peripheral surface of the first seal member 43P and the first piston 41P, the first recess 411P of the first piston 41P, and the large size of the first cylinder 40. It is defined by the x-axis positive direction side of the first seal member 43P of the diameter portion 401. The 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 on 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 passage 46S connected to the second chamber 47S.

When the piston 41 moves along the inner peripheral surface of the first cylinder 40, the sealing members 43 and 44 (lips) 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 replenishment recess 405P to 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 to the replenishment recess 405P on the outer peripheral side of the first piston 41P, and allows the flow of brake fluid in the opposite direction. The first seal member 43S suppresses the flow of brake fluid from the first chamber 47P to the replenishment recess 405S on the outer peripheral side of the second piston 41S, and allows the flow of brake fluid in the opposite direction. The second seal member 44S suppresses the flow of brake fluid from the second chamber 47S to the replenishment recess 405S on the outer peripheral side of the second piston 41S, and allows the flow of brake fluid in the opposite direction.

The spring unit 42 has 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 diameter of the outer circumference of the spring 420 is slightly smaller than the diameter of the inner circumference of the recesses 411 and 412 of the piston 41. The retainers 421,422 are bottomed cylindrical and have a cylindrical portion 424, a bottom portion 425, and a flange portion 426. The flange portion 426 extends radially outward from the opening side of the cylindrical portion 424 in a disk shape. A hole 427 penetrates the center of the bottom 425. The diameter of the outer circumference of the cylindrical portion 424 is slightly smaller than the diameter of the inner circumference 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 425 of the second retainer 422. One end of the stopper 423 has a small shaft portion 428 having a diameter smaller than that of the main body. The diameter of the thin shaft portion 428 is slightly smaller than the diameter of the hole 427 in the bottom 425 of the first retainer 421. The other end 429 of the stopper 423 is a cylinder having a diameter larger than that of the main body, and its diameter is slightly smaller than the inner circumference of the cylindrical portion 424 of the second retainer 422, and the diameter of the hole 427 in the bottom 425 of the second retainer 422. Greater.

One end side of the spring 420 surrounds the cylindrical portion 424 of the first retainer 421, and one end of the spring 420 contacts the flange portion 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 contacts 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 of the bottom 425 of the first retainer 421. The body of the stopper 423 fits into the hole 427 in the bottom 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 the retainers 421 and 422, respectively. The extension of the spring 420 in the axial direction is restricted by the stopper 423, and the spring 420 is in a state of being constantly compressed and deformed by compressive elasticity within a predetermined amount in the axial direction. The maximum length of the spring 420 is limited by the contact of the other end 429 of the stopper 423 with the bottom 425 of the second retainer 422. The main body of the stopper 423 moves along the inner circumference 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 circumference 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 housed in the first chamber 47P, and the second spring unit 42S is housed 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 side of the first spring unit 42P fits into the second recess 412P of the first piston 41P, and the flange 426 of the first retainer 421P contacts 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 side of the second spring unit 42S fits into the second recess 412S of the second piston 41S, and the flange 426 of the first retainer 421S contacts the bottom (wall 413S) of the second recess 412S. The x-axis negative direction side of the second spring unit 42S (the flange portion 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 inside the first chamber 47P in the axial direction of the first cylinder 40, and is between the first piston 41P and the second piston 41S. 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 is in a state of being compressed with the inner surfaces of the second piston 41S and the first cylinder 40. Is between. The spring 420P constantly urges the first piston 41P in the positive x-axis direction, and the spring 420S functions as a return spring that constantly urges the second piston 41S in the positive x-axis direction. 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 may be a disc spring or the like as well as a coil spring. Further, the material of the spring 420 is not limited to metal, but may be non-metal such as rubber.

When the flange portion 30 (surface 300) of the push rod 3 comes into contact with the periphery (surface 403) of the hole 404 of the first cylinder 40, the push rod 3 moves in the positive direction of the x-axis, that is, both pistons 41P, The movement of the 41S in the positive x-axis direction is restricted. In this state, that is, in the initial state in which both pistons 41P and 41S are maximally displaced 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 replenishment recess 405 and the lip of the second seal member 44) and communicates with the replenishment 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 the replenishment liquid passage 45P, the replenishment recess 405P, and the 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 passage 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 x-axis positive end of the first piston 41P. The guide member 910 fits into the magnet holder 911. The sensor body 913 has 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 the x-axis direction movement 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 electric signal in response to the movement of the magnet 912. As a result, the stroke sensor 91 detects the amount of movement (pedal stroke) of the first piston 41P in the x-axis direction. The circumferential displacement of the magnet 912 with respect to the detection portion of the sensor body 913 is regulated by the guide member 910 fitted in the magnet holder 911. This improves the detection accuracy of the stroke sensor 91.

As shown in FIG. 8, the hydraulic unit 5 includes a housing 50, a motor 80, a pump 8, a plurality of solenoid valves 71, and the like. The housing 50 houses a valve body such as a pump 8 and a solenoid valve 71 inside the housing 50. Inside the housing 50, there are circuits (brake hydraulic circuits) of the above two systems (first system and second system) through which brake fluid flows. This circuit contains multiple liquid channels. A plurality of ports are opened on 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 with the liquid passages outside the housing 50 (pipe 10M, etc.). 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 the 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 provided with a rotating shaft, and is installed on one side of the housing 50. The motor 80 may be a brushed motor or a brushless motor provided with a resolver that detects the rotation angle or rotation speed of the rotation shaft. The pump 8 is a second hydraulic pressure source driven by the motor 80 and capable of supplying hydraulic 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 solenoid valve is a control valve that operates in response to a control signal, and has a solenoid and a valve body. The valve body strokes according to the energization of the solenoid to switch the opening and closing of the liquid passage (connecting and connecting the liquid passage). 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 shutoff valve 71, a pressure boosting 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 shutoff valve 71 (first valve 71P, second valve 71S), pressure boosting valve 72, and pressure regulating valve 74 are normally open valves that open 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 are closed in a non-energized state. The shutoff valve 71, the pressure boosting valve 72, and the pressure regulating valve 74 are proportional control valves in which the opening degree of the valve is 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 in which the opening and closing of the valves is controlled in a binary manner. Note that 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 passages are supply liquid passage 11 (first liquid passage 11P, second liquid passage 11S), suction liquid passage 12, discharge liquid passage 13, pressure adjusting liquid passage 14, decompression liquid passage 15, positive pressure liquid passage 16. , A back pressure fluid passage 17, a back pressure supply fluid passage 18, and a replenishment fluid passage 19. The supply liquid passage 11 has a first liquid passage 11P and a second liquid passage 11S. One end side of the first liquid passage 11P is connected to the first port 51P. The other end side of the first liquid passage 11P branches into a liquid passage 11a for the front left wheel and a liquid passage 11d for the rear right wheel. Each liquid passage 11a, 11d connects to the corresponding wheel cylinder port 52a, 52d. One end side of the second liquid passage 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 liquid passage 11b, 11c connects to the corresponding wheel cylinder port 52b, 52c. There is a shutoff valve 71 on the one end side of the supply liquid passage 11. In the supply liquid passage 11, there is an orifice 111 on the side of the master cylinder port 51 with respect to the shutoff valve 71. Each liquid passage 11a to 11d has a pressure boosting valve 72. In each of the liquid passages 11a to 11d, there is an orifice 112 on the side of the shutoff valve 71 with respect to the booster valve 72. Bypassing the booster valve 72 (and the orifice 112), there is a bypass liquid passage 110 in parallel with each liquid passage 11a to 11d. The liquid passage 110 has a check valve 720. The valve 720 only allows the flow of brake fluid from the wheel cylinder port 52 side to the master cylinder port 51 side.

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

The positive pressure liquid passage 16 connects between the first port 51P and the shutoff valve 71P in the first liquid passage 11P and the positive pressure port 54. One end of the back pressure fluid passage 17 is connected to the back pressure port 55. The other end of the liquid passage 17 is connected to the liquid storage chamber 57. The liquid passage 17 has a simulator out valve 77. In the liquid passage 17, there is an orifice 171 on the side of the back pressure port 55 with respect to the simulator out valve 77. There is a bypass fluid passage 170 in parallel with the fluid passage 17, bypassing the simulator out valve 77 (and orifice 171). The liquid passage 170 has a check valve 770. The valve 770 only allows the flow of brake fluid from the side of the reservoir 57 to the side of the back pressure port 55. The back pressure supply liquid passage 18 branches from between the back pressure port 55 and the simulator out valve 77 in the back pressure liquid passage 17, and is between the shutoff valve 71P and the pressure boosting valves 72a and 72d in the first liquid passage 11P. Connecting. The liquid passage 18 has a simulator-in valve 78. In the liquid passage 18, there is an orifice 181 on the side of the first liquid passage 11P with respect to the simulator-in valve 78. There is a bypass liquid passage 180 in parallel with the liquid passage 18 bypassing the simulator-in valve 78 (and the orifice 181). The liquid passage 180 has a check valve 780. The valve 780 allows only the flow of brake fluid from the back pressure fluid passage 17 side to the first fluid passage 11P side. The replenishment liquid passage 19 connects the liquid storage chamber 57 and the replenishment port 56. In Example 3, a part of the replenishment liquid passage 19 is common with the decompression liquid passage 15.

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

The stroke simulator 6 operates in response to the driver's brake 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, 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 surface of the housing 50. FIG. 8 shows a cross section passing through the axis of the stroke simulator 6. For convenience of explanation, a y-axis is provided in the moving direction (axis direction) of the third piston 61, and the side on which the third piston 61 moves in response to the stepping operation of the brake pedal 100 is negative.

The inner circumference of the second cylinder 60 has a small diameter portion 601 and a large diameter portion 602. These portions 601,602 are cylindrical and extend in the y-axis direction on substantially the same axis as each other. 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 a seal groove 605,606. 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 an annular shape extending in the circumferential direction (hereinafter, circumferential direction) of the axis. 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 y-axis positive direction side of the replenishment recess 603, and the second groove 606 is on the y-axis negative direction side of the replenishment recess 603. The first seal member 64 is installed in the first groove 605, and the second seal member 65 is installed in the second groove 606. The sealing members 64 and 65 are annular packings having a U-shaped cross section. The first seal member 64 opens in the positive direction of the y-axis, and the second seal member 65 opens in the negative direction of the y-axis. 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 end of the large diameter portion 602 opens to the outer surface 600 of the second cylinder 60. This opening is closed by the lid member 66. The outer circumference of the lid member 66 is cylindrical. On the outer circumference of the lid member 66, there is a seal groove 660 extending in the direction around the axis thereof. 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 passage 691, a back pressure liquid passage 692, a make-up liquid passage 693, and a discharge liquid passage 694,695. These liquid passages 691 and the like extend inside the second cylinder 60 in the radial direction (hereinafter, radial direction) with respect to the axis and open to the small diameter portion 601 or the large diameter portion 602 and reach the outer surface 600 of the second cylinder 60. Open. Breeder valves 681 and 682 are installed at the openings of the drainage channels 694 and 695 on the outer surface 600, respectively. The positive pressure liquid passage 691 and the first discharge liquid passage 694 are opened on 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 passage 692 and the second discharge liquid passage 695. Opens in the positive direction of the y-axis of the large diameter portion 602. The replenishment channel 693 opens into the replenishment recess 603.

The third piston 61 is housed inside the second cylinder 60 so as to be movable in the axial direction (y-axis direction) of the second cylinder 60. The outer circumference of the third piston 61 is cylindrical. The diameter of the third piston 61 (outer peripheral surface) is slightly smaller than the diameter of the small diameter portion 601 and is substantially equal to the diameter of the first and second pistons 41P and 41S (outer peripheral surface). The lips of the sealing members 64 and 65 are 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 recesses 611 and 612 are substantially equal. At the bottom of both recesses 611,612, there is a wall 613 that separates both recesses 611,612. The wall 613 has a columnar convex portion 614 protruding toward the second concave portion 612. The peripheral wall of the first recess 611 in the third piston 61 has a supply hole 615, and the peripheral wall of the second recess 612 has a supply hole 616. Both holes 615,616 extend radially with respect to the axis of the piston 61, penetrate the peripheral wall, and open inside (recessed portions 611,612) and outside (outer surface 610 of the piston 61) of the peripheral wall. A plurality (for example, four) of both 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 on the opening side of the first recess 611 with respect to the bottom side. The supply hole 616 is on the bottom side of the second recess 612 with respect to the opening side.

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

When the third piston 61 moves along the inner peripheral surface of the second cylinder 60, the sealing members 64 and 65 are in sliding contact with the outer peripheral surface 610 of the third piston 61. 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 to the replenishment recess 603 on the outer peripheral side of the third piston 61, and allows the flow of brake fluid in the opposite 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 opposite 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 columnar 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 constant of the second spring 630 are each larger than those of the first spring 620. Like the first retainer 621, the third retainer 631 has a bottomed cylindrical shape and has a cylindrical portion 632, a bottom portion 633, and a flange portion 634. The diameter of the outer circumference of the cylindrical portion 632 is slightly smaller than the diameter of the inner circumference 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. There is a bottomed annular recess 663 between the inner circumference of the lid member 66 and the outer circumference of the convex portion 661. The second elastic member 63A is made of rubber (resin) and is formed in a columnar shape having a constricted center in the axial direction of the outer circumference.

Both spring units 62 and 63 are housed in the back pressure chamber 608. The y-axis positive direction side of the first spring unit 62 fits into the second recess 612 of the third piston 61. The convex portion 614 of the third piston 61 fits into the inner circumference of the cylindrical portion 624 of the second retainer 622, and the flange portion 626 of the second retainer 622 contacts the bottom portion (wall 613) of the second concave portion 612. The first elastic member 62A is housed 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 side of the first spring unit 62 fits into the cylindrical portion 632 of the third retainer 631, and the flange portion 626 of the first retainer 621 contacts the bottom portion 633 of the third retainer 631. The y-axis positive side of the second spring 630 surrounds the cylindrical portion 632 of the third retainer 631, and the y-axis positive end of the second spring 630 is in contact with the flange 634 of the third retainer 631. The y-axis negative direction side of the second spring 630 surrounds the convex portion 661 of the lid member 66 and fits into the concave portion 663, and the y-axis negative direction end of the second spring 630 contacts the bottom of the concave portion 663. The second elastic member 63A is housed in the inner circumference (recessed 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 function as the inner surface of the third piston 61 and the lid member 66 (the inner surface of the second cylinder 60) in a state of being compressed inside the back pressure chamber 608 in the axial direction of the second cylinder 60. It is between the lid member 66 and the surface on the positive side of the y-axis). Both springs 620 and 630 function as return springs that constantly urge the third piston 61 in the positive direction of the y-axis. The set load of the first spring 620 is equal to or less than the set load of the second spring 630. The springs 620 and 630 may be elastic bodies, and may be not limited to coil springs but may be disc springs or the like. Further, 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 positive direction of the y-axis is restricted by contacting the third piston 61 (the end face in the positive direction of the y-axis) with the inner surface of the second cylinder 60 (the end surface in the positive direction of the y-axis on the inner peripheral side). Will be done. In this state, that is, in the initial state in which the third piston 61 is maximally displaced in the positive direction of the y-axis, the opening of the supply hole 615 on the outer peripheral surface of the third piston 61 is the positive pressure liquid passage 691 in the small diameter portion 601 in the y-axis direction. It overlaps with the opening of and communicates with the positive pressure liquid passage 691. Further, in the above initial state, the opening of the supply hole 616 on the outer peripheral surface of the third piston 61 overlaps the second groove 606 in the small diameter portion 601 in the y-axis direction, and passes through the second groove 606 to the second seal member 65. It communicates with the communication groove 604 and the supply recess 603 on the positive side of the y-axis from the lip. In the above 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 with the bottom 633.

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

As the driver operates the brake, the pressure of the brake fluid 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 brake fluid to 47P and 47S in each chamber. The brake fluid flowing out of each chamber 47P, 47S can be supplied to each wheel cylinder 101 via the supply liquid 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 simulates the operating reaction force (pedal reaction force) of the brake pedal 100. In this way, the master cylinder 4, the reservoir tank 2, and the stroke simulator 6 function as a braking device.

The 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 sensor 27,28 (connector 270,280) via the harness 94. In addition, the ECU 90 is electrically connected to the hydraulic pressure sensors 92 and 93, and is also connected to other control devices on the vehicle side via an in-vehicle network such as CAN. Based on the detected values of the sensor 91, etc., the information on the running condition input from the vehicle side, and the built-in program (stored in the ROM), the ECU 90 opens and closes the solenoid valve 71, etc., and rotates the motor 80 (the number of revolutions of the motor 80). That is, the discharge amount of the pump 8) is controlled. Thereby, the wheel cylinder hydraulic pressure (hydraulic braking force) of each wheel FL to RR is controlled. The ECU 90 can execute various brake controls by controlling the hydraulic pressure of the wheel cylinder. Brake control includes boost control to reduce the driver's braking force, anti-lock braking control (ABS) to suppress wheel slip due to braking, traction control to suppress wheel drive slip, and vehicle. Includes brake control for motion control, automatic brake control such as preceding vehicle follow-up control, and regenerative cooperative brake control. Vehicle motion control includes vehicle behavior stabilization control such as sideslip prevention.

The ECU 90 has a receiving unit 901, a calculation unit 902, and a driving unit 903. The receiving unit 901 receives the detected value of the sensor 91 and the like and the information from the vehicle-mounted network. The calculation unit 902 calculates the target wheel cylinder hydraulic pressure and other calculations based on the information input from the reception unit 901. For example, the displacement amount (pedal stroke) of the brake pedal 100 as the brake operation amount is detected based on the detection value of the stroke sensor 91. During boost control, based on the detected pedal stroke, a predetermined boost ratio, that is, the ideal relationship characteristic between the pedal stroke and the driver's required brake fluid pressure (vehicle deceleration required by the driver) is realized. Target wheel cylinder fluid pressure to be set. At the time of regenerative cooperative braking 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, the target wheel cylinder hydraulic pressures of the wheels FL to RR are calculated so as to realize a desired vehicle motion state based on, for example, the detected vehicle motion state amount (lateral acceleration, etc.). The calculation unit 902 calculates a command for driving an actuator (each solenoid valve 71 or the like or a motor 80) so as to realize the target wheel cylinder hydraulic pressure, and outputs this to the drive unit 903. The drive unit 903 supplies electric power to the actuator in response to a command signal from the calculation unit 902. As described above, the hydraulic pressure unit 5, the hydraulic pressure sensors 92, 93, etc., and the ECU 90 function as the hydraulic pressure control device.

Although the arithmetic unit 902 and the receiving unit 901 are realized by software in the microcomputer in the embodiment, they may be realized by electronic circuits. Calculation means not only mathematical calculation but also general processing on software. The receiver 901 may be the interface of the microcomputer or the software in the microcomputer. The drive unit 903 includes a PWM duty value calculation unit, an inverter, and the like. The command signal may be related to a current value, or may be related to a torque or a displacement amount. For the calculation unit 902, the target wheel cylinder hydraulic pressure that realizes a predetermined boost ratio may be set by a map in the microcomputer or by a calculation.

The ECU 90 deactivates the pump 8 and controls the shutoff valve 71 in the opening direction. In this state, the liquid passage (supply liquid passage 11) connecting the chambers 47P and 47S of the master cylinder 4 and the wheel cylinder 101 is the foil cylinder liquid due to the master cylinder hydraulic pressure generated by using the pedaling force of the brake pedal 100. A pedal brake (non-boosting control) that creates pressure is realized. During pedaling braking, the ECU 90 controls the simulator in valve 78 and the simulator out valve 77 in the closed direction. As a result, the stroke simulator 6 is inactive.

By controlling the second unit 1B, the ECU 90 uses the hydraulic pressure generated by the pump 8 to control the hydraulic pressure of each foil cylinder 101 (driver) while the communication between the master cylinder 4 and the wheel cylinder 101 is cut off. It can be controlled individually (independently of the braking operation by). The ECU 90 operates the pump 8 and controls the shutoff valve 71 in the closing direction. In this state, the liquid passages (suction liquid passage 12, discharge liquid passage 13, etc.) connecting the liquid storage chamber 57 and the wheel cylinder 101 create a foil cylinder hydraulic pressure by the liquid pressure generated by using the pump 8. A so-called brake-by-wire system is realized. The pump 8 sucks the brake fluid in the liquid reservoir 57 through the suction liquid passage 12, and discharges the brake fluid into the discharge liquid passage 13 (communication liquid passage 13P, 13S). Brake fluid is replenished from the reservoir tank 2 to the liquid reservoir 57 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 booster control, the ECU 90 operates the pump 8 at a predetermined rotation speed, closing the shutoff valve 71 in the closing direction, the booster valve 72 in the opening direction, the communication valve 73 in the opening direction, and the pressure reducing valve 75 in the closing direction. To control. The opening and closing of the pressure regulating valve 74 is controlled so that the hydraulic pressure in the discharge liquid passage 13, which is the hydraulic pressure on the upstream side of the pressure regulating valve 74, becomes the target hydraulic pressure according to the target wheel cylinder hydraulic pressure. As a result, the target wheel cylinder hydraulic pressure is achieved. The hydraulic pressure on the upstream side is obtained by using one or a plurality of detected values (for example, an average value) of the hydraulic pressure sensors 92, 93P, 93S. In booster control, instead of the engine negative pressure booster, the pump 8 is used as the hydraulic pressure source to create a wheel cylinder hydraulic pressure higher than the master cylinder hydraulic pressure. As a result, the brake operating force is assisted by generating a hydraulic braking force that is insufficient for the driver's braking operating force.

At the time of 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. As a result, the stroke simulator 6 operates. According to the driver's brake operation, the brake fluid flows out from 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 urging force of the first and second springs 620 and 630. The brake fluid flowing out of the back pressure chamber 608 is supplied to the liquid reservoir 57 through the back pressure fluid passage 17 (simulator out valve 77). Specifically, the brake fluid flowing into the positive pressure chamber 607 operates (strokes) the third piston 61. 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) and the stopper 623 (the other end 629) come into contact with each other. The first elastic member 62A is compressively elastically deformed. As a result, the compressive deformation of the first spring 620 is regulated, and the impact at the time of regulation is mitigated. 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) and the third retainer 631 (the bottom portion 633) come into contact with each other, and the second elastic member 63A is compressed and elastic. Deform. As a result, the compressive deformation of the second spring 630 is regulated, and the impact at the time of regulation is alleviated. The first spring 620 and the second spring 630, which have different spring constants, are connected in series, and these are elastically deformed step by step. As a result, the characteristics of both springs 620 and 630 as a whole (characteristics of changes in the spring coefficient with respect to the amount of deformation) become non-linear. Therefore, the pedal reaction force generated by the stroke simulator 6 in response 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 of the back pressure chamber 608 is supplied to the supply liquid passage 11 through the back pressure supply liquid passage 18 (bypass liquid passage 180 and check valve 780), and is supplied toward the wheel cylinder 101. .. As a result, the boost response of the 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 simulator out valve 77 is controlled in the opening direction so that the brake fluid outflow destination from the back pressure chamber 608 becomes the liquid reservoir 57. Can be switched. The flow path 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 controlling the simulator-out valve 77 in the closing direction.

If a power failure occurs during the operation of the stroke simulator 6, the simulator out valve 77 is closed. Due to the force of the springs 620 and 630, the third piston 61 strokes in the positive y-axis direction toward the initial position. When the replenishment hole 616 of the third piston 61 returns to the positive side of the y-axis 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 storage chamber 57 (reservoir tank 2) to the back pressure chamber 608 via the replenishment liquid passage 19. The replenishment liquid passage 693, the replenishment recess 603, and the like 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 the pressure receiving area of the third piston 61 in the first chamber 47P is A3. The pressure receiving area of the second piston 41S is A4. The hydraulic pressure of the first chamber 47P is P1, the hydraulic pressure of the second chamber 47S is P2, and the hydraulic pressure of 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) are substantially equal to each other, the equation (1) holds.
A1 = A2 = A3 = A4… (1)
Hereinafter, the positive and negative signs of the force F follow the positive and negative directions in the x-axis and y-axis directions. Let Fp1 be the force due to the hydraulic pressure P1 acting on the first piston 41P, Fp2 be the force due to the hydraulic pressure P1 and hydraulic pressure P2 acting on the second piston 41S, and Fp3 be the force due to the hydraulic pressure P3 acting on the third piston 61. , Equations (2), (3) and (4) hold.
Fp1 = P1 × A1… (2)
Fp2 = P2 × A2-P1 × A4… (3)
Fp3 = -P3 × A3… (4)
From equations (1) and (3), equation (5) holds.
Fp2 = (P2-P1) × A2… (5)
If P1 = P3, then Eq. (6) holds from Eq. (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, and the resultant force of the spring 420P and the 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 spring 420P) is fset1, fs2 (set load of spring 420S) is fset2, Fs1 is Fset1, and Fs2 is Fset2. Let Fs3 be Fset3 when the stroke simulator 6 is not operating (initial state). Let F1 be the resultant force of Fp1 and Fs1 acting on the first piston 41P, F2 be the resultant force of Fp2 and Fs2 acting on the second piston 41S, and F3 be the resultant force of Fp3 and Fs3 acting on the third piston 61. ) (9) (10) holds.
F1 = Fp1 + Fs1… (8)
F2 = Fp2 + Fs2… (9)
F3 = Fp3 + Fs3… (10)

The specifications of each component 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 operating (stroke) from the stopped state, the first piston 41P and the third piston 61 are in a stroked 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) The third piston 61 and the second piston 41S start the stroke after the first piston 41P starts 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 booster valve 72 is normally linearly controlled, and by switching to pulse control according to the conditions shown in Examples 1 and 2, the same effects as in Examples 1 and 2 can be obtained.

[Technical ideas that can be grasped from the examples]
Although the embodiment for carrying out the present invention has been described above based on the examples, the specific configuration of the present invention is not limited to the configuration shown in the examples and does not deviate from the gist of the invention. Even if there is a design change or the like, it is included in the present invention. The technical ideas that can be grasped from the examples are described below.
(1) The brake control device of the present technical idea is in one aspect thereof.
A connecting liquid passage connected to a wheel cylinder that can apply braking force to the wheels of the vehicle according to the brake fluid pressure,
The pressure booster valve in the connecting liquid passage and
Linear control for controlling the current energizing the booster valve portion and pulse control for controlling the time for opening the booster valve portion are performed according to the input signal based on the acquired ground contact road surface condition of the wheel portion. Control unit to switch and
Equipped with.
(2) In a more preferable embodiment, in the above embodiment,
The control unit switches to the pulse control when the friction coefficient of the ground contact surface is higher than when it is low.
(3) In another preferred embodiment, in any of the above embodiments,
The wheel portion includes a first wheel portion which is one of the left and right wheels of the vehicle and a second wheel portion which is the other of the left and right wheels.
The control unit switches to the pulse control when the friction coefficient of the ground contact road surface is lower on the second wheel portion than on the first wheel portion on the split road surface.
(4) In yet another preferred embodiment, in any of the above embodiments,
The first wheel portion includes a first front wheel which is a front wheel of the vehicle and a first rear wheel which is a rear wheel of the vehicle.
The second wheel portion includes a second front wheel which is a front wheel of the vehicle and a second rear wheel which is a rear wheel of the vehicle.
The pressure boosting valve portion includes a first pressure boosting valve corresponding to the first front wheel, a second pressure boosting valve corresponding to the first rear wheel, a third pressure boosting valve corresponding to the second front wheel, and the second rear wheel. Equipped with a 4th booster valve corresponding to the wheel,
The control unit switches only the second booster valve to the pulse control.
(5) In yet another preferred embodiment, in any of the above embodiments,
The wheel portion includes a first wheel portion which is one of the left and right wheels of the vehicle and a second wheel portion which is the other of the left and right wheels.
The first wheel portion includes a first front wheel which is a front wheel of the vehicle and a first rear wheel which is a rear wheel of the vehicle.
The second wheel portion includes a second front wheel which is a front wheel of the vehicle and a second rear wheel which is a rear wheel of the vehicle.
The pressure boosting valve portion includes a first pressure boosting valve corresponding to the first front wheel, a second pressure boosting valve corresponding to the first rear wheel, a third pressure boosting valve corresponding to the second front wheel, and the second rear wheel. Equipped with a 4th booster valve corresponding to the wheel,
The control unit switches at least one of the first booster valve, the second booster valve, the third booster valve, and the fourth booster valve.
(6) In yet another preferred embodiment, in any of the above embodiments,
The control unit switches to the pulse control during ABS control.
(7) In yet 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 the set threshold.
(8) In yet another preferred embodiment, in any of the above embodiments,
The wheel portion includes a first wheel portion which is one of the left and right wheels of the vehicle and a second wheel portion which is the other of the left and right wheels.
When the braking force generated in the first wheel portion is larger than the value obtained by adding a predetermined value to the braking force generated in the second wheel portion, the control unit switches to the pulse control.

(9) From another point of view, the brake control method of the present technical idea is, in one aspect thereof.
The first step to acquire information based on the condition of the ground contact road surface of the wheel of the vehicle,
Linear control that controls the current that energizes the pressure booster valve in the connecting liquid passage that connects to the wheel cylinder that can apply braking force to the wheel, and pulse control that controls the time to open the pressure booster valve. In the second step, which is switched according to the state of the ground contact road surface of the wheel portion acquired in the first step, and
Equipped with.
(10) In a more preferable embodiment, in the above embodiment,
In the second step, when the friction coefficient of the ground contact road surface is higher than the case where the friction coefficient is low, the pulse control is switched to.
(11) In yet another preferred embodiment, in any of the above embodiments,
In the second step,
If the second wheel portion, which is the other of the left and right wheels, has a split road surface having a lower friction coefficient of the ground contact road surface with respect to the first wheel portion, which is one of the left and right wheels, the pulse control is switched to. ..
(12) In yet another preferred embodiment, in any of the above embodiments,
In the second step,
Of the first wheel portion, the front wheel is the first front wheel, the rear wheel is the first rear wheel, the front wheel of the second wheel portion is the second front wheel, the rear wheel is the second rear wheel, and the pressure boosting valve portion. The pressure boosting valve corresponding to the first front wheel is the first pressure booster valve, the pressure booster valve corresponding to the first rear wheel is the second pressure booster valve, the pressure booster valve corresponding to the second front wheel is the third pressure booster valve, and the second rear wheel. When the pressure booster valve corresponding to the wheel is the fourth pressure booster valve,
Only the second booster valve is switched to the pulse control.
(13) In yet another preferred embodiment, in any of the above embodiments,
In the second step,
Of the first wheel portion, the front wheel is the first front wheel, the rear wheel is the first rear wheel, the front wheel of the second wheel portion is the second front wheel, the rear wheel is the second rear wheel, and the pressure boosting valve portion. The pressure boosting valve corresponding to the first front wheel is the first pressure booster valve, the pressure booster valve corresponding to the first rear wheel is the second pressure booster valve, the pressure booster valve corresponding to the second front wheel is the third pressure booster valve, and the second rear wheel. When the pressure booster valve corresponding to the wheel is the fourth pressure booster valve,
At least one of the first booster valve, the second booster valve, the third booster valve, and the fourth booster valve is switched.
(14) In yet another preferred embodiment, in any of the above embodiments,
In the second step, the pulse control is switched to during the ABS control.
(15) In yet another preferred embodiment, in any of the above embodiments,
In the second step, when the deceleration of the vehicle is larger than the set threshold value, the pulse control is switched to.
(16) In yet another preferred embodiment, in any of the above embodiments,
In the second step,
When the braking force generated in the first wheel portion of one of the left and right wheels of the wheel portion is larger than the value obtained by adding a predetermined value to the braking force generated in the second wheel portion of the other of the left and right wheels, the pulse Switch to control.

Z1 pipeline
Z2 pipeline (connecting liquid channel)
Z3 gate out valve
Z4 Master Cylinder Hydraulic Sensor
Z6 solenoid in valve
Z13 Pressure Control Reservoir
Z16 check valve
Z21 solenoid
Z22 valve body
BCU brake control unit (control unit)
ZBP brake pedal
ZM / C Master Cylinder
P pump
W / C wheel cylinder
72 boost valve

Claims (8)

A connecting liquid passage connected to a wheel cylinder that can apply braking force to the wheels of the vehicle according to the brake fluid pressure,
The pressure booster valve in the connecting liquid passage and
Linear control for controlling the current energizing the booster valve portion and pulse control for controlling the time for opening the booster valve portion are performed according to the input signal based on the acquired ground contact road surface condition of the wheel portion. Control unit to switch and
A brake control apparatus provided with,
The wheel portion includes a first wheel portion which is one of the left and right wheels of the vehicle and a second wheel portion which is the other of the left and right wheels.
The first wheel portion includes a first front wheel which is a front wheel of the vehicle and a first rear wheel which is a rear wheel of the vehicle.
The second wheel portion includes a second front wheel which is a front wheel of the vehicle and a second rear wheel which is a rear wheel of the vehicle.
The pressure boosting valve portion includes a first pressure boosting valve corresponding to the first front wheel, a second pressure boosting valve corresponding to the first rear wheel, a third pressure boosting valve corresponding to the second front wheel, and the second rear wheel. Equipped with a 4th booster valve corresponding to the wheel,
The control unit includes the first booster valve, the second booster valve, and the third booster valve when the friction coefficient of the ground contact road surface is other than the split road surface where the second wheel portion is lower than the first wheel portion. And when the fourth pressure boosting valve is linearly controlled and the friction coefficient of the ground contact road surface is lower on the second wheel portion than on the first wheel portion, only the second booster valve is controlled by the linear control. A brake control device characterized by switching to the pulse control . A connecting liquid passage connected to a wheel cylinder that can apply braking force to the wheels of the vehicle according to the brake fluid pressure,
The pressure booster valve in the connecting liquid passage and
Linear control for controlling the current energizing the booster valve portion and pulse control for controlling the time for opening the booster valve portion are performed according to the input signal based on the acquired ground contact road surface condition of the wheel portion. Control unit to switch and
It is a brake control device equipped with
The control unit is a brake control device characterized by switching from the linear control to the pulse control when the deceleration of the vehicle is larger than a set threshold value during ABS control. A connecting liquid passage connected to a wheel cylinder that can apply braking force to the wheels of the vehicle according to the brake fluid pressure,
The pressure booster valve in the connecting liquid passage and
Linear control for controlling the current energizing the booster valve portion and pulse control for controlling the time for opening the booster valve portion are performed according to the input signal based on the acquired ground contact road surface condition of the wheel portion. Control unit to switch and
It is a brake control device equipped with
The wheel portion includes a first wheel portion which is one of the left and right wheels of the vehicle and a second wheel portion which is the other of the left and right wheels.
When the braking force generated in the first wheel portion is larger than the value obtained by adding a predetermined value to the braking force generated in the second wheel portion during ABS control, the control unit performs the pulse control from the linear control. Brake control method characterized by switching to. In the brake control device according to claim 2 or 3.
The wheel portion includes a first wheel portion which is one of the left and right wheels of the vehicle and a second wheel portion which is the other of the left and right wheels.
The first wheel portion includes a first front wheel which is a front wheel of the vehicle and a first rear wheel which is a rear wheel of the vehicle.
The second wheel portion includes a second front wheel which is a front wheel of the vehicle and a second rear wheel which is a rear wheel of the vehicle.
The pressure boosting valve portion includes a first pressure boosting valve corresponding to the first front wheel, a second pressure boosting valve corresponding to the first rear wheel, a third pressure boosting valve corresponding to the second front wheel, and the second rear wheel. Equipped with a 4th booster valve corresponding to the wheel,
The control unit is characterized in that at least one of the first booster valve, the second booster valve, the third booster valve, and the fourth booster valve is switched from the linear control to the pulse control. apparatus. The first step to acquire information based on the condition of the ground contact road surface of the wheel of the vehicle,
Linear control that controls the current that energizes the pressure booster valve in the connecting liquid passage that connects to the wheel cylinder that can apply braking force to the wheel, and pulse control that controls the time to open the pressure booster valve. In the second step, which is switched according to the state of the ground contact road surface of the wheel portion acquired in the first step, and
It is a brake control method characterized by being equipped with
The wheel portion includes a first wheel portion which is one of the left and right wheels of the vehicle and a second wheel portion which is the other of the left and right wheels.
The first wheel portion includes a first front wheel which is a front wheel of the vehicle and a first rear wheel which is a rear wheel of the vehicle.
The second wheel portion includes a second front wheel which is a front wheel of the vehicle and a second rear wheel which is a rear wheel of the vehicle.
The pressure boosting valve portion includes a first pressure boosting valve corresponding to the first front wheel, a second pressure boosting valve corresponding to the first rear wheel, a third pressure boosting valve corresponding to the second front wheel, and the second rear wheel. Equipped with a 4th booster valve corresponding to the wheel,
In the second step, when the friction coefficient of the ground contact road surface is other than the split road surface where the second wheel portion is lower than the first wheel portion, the first booster valve, the second booster valve, and the third booster are used. When the pressure valve and the fourth booster valve are linearly controlled and the friction coefficient of the ground contact road surface is lower on the second wheel portion than on the first wheel portion, only the second booster valve is linearly controlled. A brake control method characterized by switching from to the pulse control. The first step to acquire information based on the condition of the ground contact road surface of the wheel of the vehicle,
Linear control that controls the current that energizes the pressure booster valve in the connecting liquid passage that connects to the wheel cylinder that can apply braking force to the wheel, and pulse control that controls the time to open the pressure booster valve. In the second step, which is switched according to the state of the ground contact road surface of the wheel portion acquired in the first step, and
It is a brake control method characterized by being equipped with
In the second step, a brake control method comprising switching from the linear control to the pulse control when the deceleration of the vehicle is larger than a set threshold value during ABS control. The first step to acquire information based on the condition of the ground contact road surface of the wheel of the vehicle,
Linear control that controls the current that energizes the pressure booster valve in the connecting liquid passage that connects to the wheel cylinder that can apply braking force to the wheel, and pulse control that controls the time to open the pressure booster valve. In the second step, which is switched according to the state of the ground contact road surface of the wheel portion acquired in the first step, and
It is a brake control method characterized by being equipped with
The wheel portion includes a first wheel portion which is one of the left and right wheels of the vehicle and a second wheel portion which is the other of the left and right wheels.
In the second step, when the braking force generated in the first wheel portion is larger than the value obtained by adding a predetermined value to the braking force generated in the second wheel portion during ABS control, the pulse from the linear control A brake control method characterized by switching to control. In the brake control method according to claim 6 or 7.
The wheel portion includes a first wheel portion which is one of the left and right wheels of the vehicle and a second wheel portion which is the other of the left and right wheels.
The first wheel portion includes a first front wheel which is a front wheel of the vehicle and a first rear wheel which is a rear wheel of the vehicle.
The second wheel portion includes a second front wheel which is a front wheel of the vehicle and a second rear wheel which is a rear wheel of the vehicle.
The pressure boosting valve portion includes a first pressure boosting valve corresponding to the first front wheel, a second pressure boosting valve corresponding to the first rear wheel, a third pressure boosting valve corresponding to the second front wheel, and the second rear wheel. Equipped with a 4th booster valve corresponding to the wheel,
In the second step, at least one of the first booster valve, the second booster valve, the third booster valve, and the fourth booster valve is switched from the linear control to the pulse control. Control method.

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