JPH0635842Y2 - Brake fluid pressure control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a brake fluid pressure control device for controlling the fluid pressure of each brake cylinder corresponding to a front wheel and a rear wheel of a vehicle, and more particularly to a brake cylinder. The present invention relates to a brake hydraulic pressure control device including an electromagnetic hydraulic pressure control device that electromagnetically controls the hydraulic pressure.

[Conventional technology]

There is known a brake fluid pressure control device that electrically controls the hydraulic pressure level of a brake cylinder. For example, Japanese Patent Application No. 62-
That is the one described in the specification of 55083. This type of device is generally configured to include an electromagnetic hydraulic pressure control device that controls the hydraulic pressure of a hydraulic pressure source to a predetermined height by controlling the exciting current of a solenoid. This is performed by solenoid control means such as a drive circuit.

[Problems to be solved by the device]

However, it is said that electrical parts such as solenoids and solenoid control means are generally less reliable than mechanical parts. In a brake fluid pressure control device including an electromagnetic fluid pressure control device, if the solenoid or the like fails, the control of the fluid pressure of the brake cylinder that is the control target of the electromagnetic fluid pressure control device becomes defective or impossible, and the braking ability of the vehicle is reduced. There is a problem that it may become defective.

This problem also exists in the brake fluid pressure control device previously devised by the present inventor. This brake hydraulic pressure control device (a) generates a first output hydraulic pressure having a height corresponding to an operation amount of an operation member, an operation amount such as an operation stroke, and outputs the first output hydraulic pressure to the first output hydraulic pressure.
A hydraulic pressure supply device for supplying to a first brake cylinder corresponding to either one of a front wheel and a rear wheel (hereinafter referred to as a first wheel) of the vehicle via a liquid passage, and (b) a hydraulic pressure of a hydraulic pressure source. Is based on the hydraulic pressure level of the first brake cylinder, and in the event that the locked state should occur, the rear wheel is controlled to a height at which it falls simultaneously with the front wheel or slightly later to obtain the second output hydraulic pressure. , And an electromagnetic hydraulic pressure control device that supplies the second output hydraulic pressure to a second brake cylinder corresponding to one of the front wheels and the rear wheel that is not the one (hereinafter, referred to as the second wheel). In this brake hydraulic pressure control device, when the solenoid or the like of the electromagnetic hydraulic pressure control device fails, the electromagnetic hydraulic pressure control device may generate a normal second output hydraulic pressure having a height corresponding to the brake operation. No longer possible, and the second brake cylinder Brake is become inoperative. Therefore, the first brake cylinder corresponding to the first brake cylinder
Since the vehicle must be braked only by the brakes, the braking ability of the vehicle as a whole is lowered, and the required operation amount of the operating member is increased.

The present invention has been made to solve this problem.

[Means for Solving the Problems]

And the gist of the present invention is to provide a brake fluid pressure control device,
(A) The hydraulic pressure of the hydraulic pressure supply device and (b) the hydraulic pressure source is controlled to a second output hydraulic pressure by controlling the hydraulic pressure to a height according to the operation amount of the operating member, and the second output hydraulic pressure is set to the second output hydraulic pressure. The second through the second liquid passage
An electromagnetic hydraulic pressure control device that supplies the brake cylinder,
(C) Even when liquid leakage occurs in the pressure holding portion of the hydraulic pressure supply device from the electromagnetic hydraulic pressure control device to the second brake cylinder by the third liquid passage provided in the middle of the second liquid passage, It is connected to the pressure chamber that generates the first output hydraulic pressure, and in the brake operating state, the second output hydraulic pressure of the electromagnetic hydraulic pressure control device is always transmitted to the second brake cylinder, but the electromagnetic hydraulic pressure control device has failed. In this case, the transmission switching device for transmitting the first output hydraulic pressure of the hydraulic pressure supply device, and (d) the transmission switching device, which is provided in the transmission switching device, is operated due to a failure of at least one of the electromagnetic hydraulic pressure control device and the second brake cylinder. When the liquid is leaked from the pressure supply device, a shutoff means for shutting off the flow of the liquid from the transmission switching device to at least one of them is included.

It should be noted that the hydraulic pressure supply device is not limited to the type that mechanically controls the hydraulic pressure of the brake cylinder such as the master cylinder, but may be the type that electrically controls the hydraulic pressure like the electromagnetic hydraulic pressure control device. May be.

The hydraulic pressure source of the electromagnetic hydraulic pressure control device may be dedicated or may be the hydraulic pressure source of the hydraulic pressure supply device. Further, the electromagnetic hydraulic pressure control device is not limited to the one that directly controls the second output hydraulic pressure according to the operation amount of the operation member, but the first output controlled to a height corresponding to the operation amount of the operation member. It is possible to control the second output hydraulic pressure according to the hydraulic pressure, that is, indirectly control the second output hydraulic pressure according to the operation amount of the operating member.

The failure of the electromagnetic hydraulic pressure control device is not limited to the case where the electrical parts such as the solenoid thereof also fail, and the mechanical parts such as the control valve fail or the electromagnetic hydraulic pressure control device and the transmission switching device are broken. It also includes the case where the liquid passage that connects the two is damaged. The same applies when the hydraulic pressure source dedicated to the electromagnetic hydraulic pressure control device fails, but in this case, the precondition is that the presence of the dedicated hydraulic pressure source is not essential to the hydraulic pressure supply device.

[Effect of action and device]

In the brake hydraulic pressure control device according to the present invention, when the electromagnetic hydraulic pressure control device operates normally, the second output hydraulic pressure thereof is transmitted to the second brake cylinder by the transmission switching device. On the other hand, when the electromagnetic hydraulic pressure control device fails, the first output hydraulic pressure of the hydraulic pressure supply device is transmitted to the second brake cylinder by the transmission switching device instead of the second output hydraulic pressure. In this state, the hydraulic pressures of both brake cylinders are both increased by the hydraulic pressure supply device.

In the case where the present invention is implemented in such a manner that the hydraulic pressure supply device also functions as the hydraulic pressure source of the electromagnetic hydraulic pressure control device, when the electromagnetic hydraulic pressure control device fails, The hydraulic pressure of the pressure chamber that generates the first output hydraulic pressure even in the state in which the hydraulic pressure leakage from the pressure control device to the second brake cylinder occurs in the second brake cylinder through the third hydraulic passage and the transmission switching device. Therefore, the second brake cylinder will not be inoperable even if liquid leakage occurs in the pressure holding portion from the electromagnetic hydraulic pressure control device to the second brake cylinder.

As described above, according to the present invention, even if the electromagnetic hydraulic pressure control device fails, the operation of both brakes corresponding to both brake cylinders is ensured, and the reduction of the braking ability of the vehicle as a whole can be suppressed. The effect is obtained.

If the electromagnetic hydraulic pressure control device or the second brake cylinder fails in a state where the first output hydraulic pressure of the hydraulic pressure supply device is transmitted to the second brake cylinder by the transmission switching device, the brake fluid supplied from the hydraulic pressure supply device. May leak, in which case the hydraulic pressure of the first brake cylinder may not be able to rise. In that respect, in the brake fluid pressure control device according to the present invention, when the brake fluid leaks from the fluid pressure supply device due to a failure of at least one of the electromagnetic fluid pressure control device and the second brake cylinder,
The blocking means blocks the flow of the brake fluid from the transmission switching device to at least one of the above. Therefore, it is possible to avoid a situation in which the hydraulic pressure of the first brake cylinder cannot be increased due to the failure of at least one of the electromagnetic hydraulic pressure control device and the second brake cylinder.

〔Example〕

An embodiment of the present invention applied to a brake hydraulic pressure control device for a hydraulic brake device of a four-wheeled vehicle will be described in detail below with reference to the drawings.

Reference numeral 10 in FIG. 1 indicates a brake pedal as an operating member. The brake pedal 10 is connected to a brake master cylinder 14 (hereinafter simply referred to as a master cylinder) via a hydraulic booster 12, and the brake pedal is connected to the master cylinder 14.
The brake fluid pressure of the height corresponding to the operating force of 10 is generated. A front wheel cylinder 18 (first brake cylinder) of a front wheel is connected to the master cylinder 14 by a front main fluid passage (first fluid passage) 20. The hydraulic booster 12 is well known and is not indispensable for understanding the present invention, so a detailed description thereof will be omitted. The hydraulic booster 12 includes an accumulator 22 and a first accumulator passage 24.
And the reservoir 26 and the first reservoir passage 28. As is clear from the above description, in the present embodiment, the master cylinder 14 and the front main fluid passage 20 constitute a fluid pressure supply device.

Reference numeral 30 indicates a spool type proportional electromagnetic hydraulic pressure control valve (hereinafter, simply referred to as a control valve). This includes the accumulator 22, the reservoir 26 and the rear wheel cylinder 32 of the rear wheel (secondary wheel).
The brake cylinder) and the second accumulator passage 34, the second reservoir passage 36, and the rear main fluid passage (second fluid passage) 38, respectively. Control valve 30 is a practical application Sho 61-
The hydraulic pressure is the same as that described in the specification of No. 170587, and the hydraulic pressure of the rear wheel cylinder 32 (hereinafter referred to as the rear hydraulic pressure).
Is controlled to a height proportional to the magnitude of the exciting current of the solenoid.

A change valve 52 is provided in the middle of the rear main liquid passage 38 while being connected to the front main liquid passage 20 by a liquid passage (third liquid passage) 50. As a result, the rear main liquid passage 38 is divided into a control valve side passage 54 on the control valve 30 side and a wheel cylinder side passage 56 on the rear wheel cylinder 32 side. As shown in FIG. 2, the change valve 52 includes a cylindrical housing 58 and a control piston 62 slidably fitted in a cylinder bore 60 formed in the housing 58.
It has and. The control piston 62 is normally held at the forward end position (the original position shown) by a return spring 64.

An annular groove 66 is formed in an axially intermediate portion of the control piston 62, and the control piston 62 is fitted into the cylinder bore 60, so that the control piston 62 is provided with a first (forward) right side of the control piston 62. A chamber 68, a second chamber 70 in the annular groove 66, and
Third chamber 72 behind the control piston 62 (to the left in the figure)
Are formed. The first chamber 68 is in the liquid passage 50 and the second chamber is
70 is connected to the control valve side passage 54, and the third chamber 72 is connected to the wheel cylinder side passage 56. First chamber 68 and second chamber 70
The cup seals 74 and 76 prevent the liquid flow in both directions, and the second chamber 70 and the third chamber 72 allow the liquid flow from the former to the latter by the cup seal 78 and vice versa. Has been thwarted.

The control piston 62 further includes a communication passage 80 that connects the second chamber 70 and the third chamber 72, and the third chamber 72 of the communication passage 80 is provided.
An opening / closing valve 82 is provided at the side opening. This on-off valve
82 is opened by a stepped rod 84 as a valve opening member when the control piston 62 is at the forward end position.
The control piston 62 is closed by a spring 86 in a state where the control piston 62 is retracted by a small distance (moved to the left in the figure).

In the change valve 52 configured as above,
When the output hydraulic pressure of the control valve 30 is equal to or higher than the output hydraulic pressure of the master cylinder 14, the control piston 62 is at the forward end position, and the liquid of the control valve 30 is the second chamber 70, the communication passage 80, the third passage. Although it is supplied to the rear wheel cylinder 32 through the chamber 72 and the like, the output hydraulic pressure of the master cylinder 14 becomes higher than the output hydraulic pressure of the control valve 30,
Moreover, when the retracting force of the control piston 62 generated according to the hydraulic pressure difference overcomes the urging force of the return spring 64, the control piston 62 retracts and the on-off valve 82 closes.
The control valve 30 and the rear wheel cylinder 32 are shut off, and the hydraulic pressure in the first chamber 68 is controlled by the control piston 62 in the third chamber.
By being transmitted to 72, the hydraulic pressure of the rear wheel cylinder 32 is increased by the output hydraulic pressure of the master cylinder 14.

In FIG. 1, reference numeral 92 indicates a computer including a CPU, ROM, RAM, an input unit, an output unit and a bus. The input portion of the computer 92 detects a depression sensor 94 for detecting the depression of the brake pedal 10, a depression sensor 96 for detecting the depression force of the brake pedal 10, and a hydraulic pressure of the front wheel cylinder 18 (hereinafter referred to as front hydraulic pressure). Front hydraulic pressure sensor 9
8, a rear hydraulic pressure sensor 100 for detecting the rear hydraulic pressure and a rear wheel load sensor 102 for detecting the load applied to the rear wheels are connected, while the output section is a solenoid control connected to the solenoid of the control valve 30. The circuit 104 and the warning light 108 are connected. The computer 92 supplies a signal for controlling the rear hydraulic pressure to an appropriate height to the solenoid control circuit 104 based on various input signals by executing a control program (represented by a flowchart in FIG. 3) stored in the ROM. In addition, the warning light 10
By turning on 8, the driver is notified of an abnormal situation. The above control will be described in detail later.

The liquid in the reservoir 26 is pumped up by the pump 110 in the accumulator 22 and stored at a certain range of liquid pressure.
The motor 112 that drives the pump 110 is connected to the output section of the computer 92 via a motor control circuit 114, and the drive state of the pump 110 is controlled according to the hydraulic pressure in the accumulator 22 detected by the accumulator hydraulic pressure sensor 116. Is done. That is, in this embodiment, the accumulator 22, the reservoir 26, the pump 110, the motor 112, the motor control circuit 114, and the motor 112 of the computer 92 are the hydraulic pressure sources corresponding to the control valve 30 (hereinafter referred to as control valve It is called a hydraulic pressure source). Moreover, the control valve hydraulic pressure source also functions as a hydraulic pressure source for the hydraulic pressure booster 12. A level switch 120 is attached to the reservoir 26, and the liquid level of the reservoir 26 is monitored by the computer 92.

As is clear from the above description, in this embodiment,
Control valve hydraulic pressure source, control valve 30, rear main hydraulic passage 38, front hydraulic pressure sensor 98, rear hydraulic pressure sensor 100, rear wheel load sensor 102, solenoid control circuit 104, and third of computer 92
A portion that stores each step of the flowchart in the drawing and a portion that executes the same constitute an electromagnetic hydraulic pressure control device.

Next, the operation will be described.

First, a case where the electromagnetic hydraulic pressure control device operates normally will be described.

When the power is turned on, the computer 92 is activated to execute the hydraulic pressure control program represented by the flowchart of FIG. First, in step S1 (hereinafter referred to simply as S1; the same applies to the following steps), the initial flag of the CPU is reset, and in step S2, a pressure reduction command is issued to the control valve 30 so that the rear hydraulic pressure becomes 0. Will be issued. Then, in S3, it is determined whether or not the depression sensor 94 detects the depression of the brake pedal 10, and if the brake pedal 10 is operated and the determination result is YES, the steps after S4 are executed and the rear hydraulic pressure is executed. Is controlled to an appropriate height, and at the same time, the brake fluid pressure corresponding to the pedaling force of the brake pedal 10 is applied from the pressurizing chamber 16 of the master cylinder 14 to the front wheel cylinder 18
Is supplied to. On the other hand, when the brake pedal 10 is operated,
If the determination result in S3 is NO, the process returns to S1.

In S4, it is determined whether or not the initial flag is set. If the determination result is NO, that is, if S4 is executed for the first time during one continuous brake operation, a signal representing the rear wheel load is fetched from the rear wheel load sensor 102 in S5, but if YES, that is, If the execution of S4 is the second time or later, the execution of S5 is bypassed. In this embodiment, the brake fluid pressure control corresponding to one continuous brake operation is performed based on the actual rear wheel load immediately after the start of the brake operation. After the first flag is set in S6, a signal representing the pedaling force is taken in from the pedaling force sensor 96 in S7, and a signal representing the front hydraulic pressure is taken in from the front hydraulic pressure sensor 98 in S8.

In S9, the front system, to be precise, the master cylinder
14, front wheel cylinder 18, front main fluid passage 20 connecting them, master cylinder 14 and change valve 5
1st chamber 6 of liquid valve 50 and change valve 52 connecting to 2
It is detected whether or not 8 has failed. That is, even though the actual brake pedal force exceeds the value for increasing the front hydraulic pressure to 0.5 kg / cm ₂ , the front hydraulic pressure is 0
It is determined whether or not it is less than or equal to a constant value close to.
If the determination result is NO, that is, if the front system is normal, S10 and subsequent steps are executed, and the determination result is YES, that is,
If the front system has failed, S15 and subsequent steps are executed.

First, the case where the front system is normal will be described. In S10, after a command to turn off the warning light 108 is issued,
In S11, the target value of the rear hydraulic pressure is calculated by executing a normal-time hydraulic pressure calculation program (not shown) in the ROM.
As shown in the graph of FIG. 4, the target value of the rear hydraulic pressure is set to a value slightly smaller than the ideal value of the rear hydraulic pressure corresponding to the front hydraulic pressure and the rear wheel load, and should it be locked. In case of falling into the rear wheel, the rear wheel falls into a position slightly behind the front wheel. In the present embodiment, a calculation formula having variables of the front hydraulic pressure and the rear wheel load is stored in the ROM, and the target value of the rear hydraulic pressure is calculated by this calculation formula. Note that FIG. 4 representatively shows an empty vehicle and a fixed volume vehicle. Then, in S12, a signal representing the current rear hydraulic pressure is fetched from the rear hydraulic pressure sensor 100, and in S13, the control amount of the rear hydraulic pressure to be controlled this time is calculated by subtracting the current value from the target value. The control valve 30 is controlled based on the control amount calculated in S14, and the process returns to the execution of S3.

The liquid of the control valve 30 controlled as described above is supplied to the second chamber 70 of the change valve 52 via the control valve side passage 54 as shown in FIG. The output fluid pressure of the control valve 30 is always set to be higher than the output fluid pressure of the master cylinder 14 in the brake operating state.
52 is maintained in the state shown in FIG. 2, and the output hydraulic pressure of the control valve 30 is supplied to the rear wheel cylinder 32.

On the other hand, if the front system has failed,
After the determination result in S9 of FIG. 2 is YES and the warning light 108 is turned on in S15, the rear hydraulic pressure is executed by executing the failure hydraulic pressure calculation program (not shown) stored in the ROM in S16. The target value of is calculated. The ROM stores a formula for calculating the rear hydraulic pressure, which is a height that compensates for the decrease in the braking ability of the entire vehicle due to the front failure, with the brake pedal force and the rear wheel load as variables.
The target value of the rear hydraulic pressure is calculated by this calculation formula. After that, S12 and the subsequent steps are executed, and the rear hydraulic pressure is controlled to an appropriate height when it fails.

Also in this case, the liquid of the control valve 30 is supplied to the rear wheel cylinder 32 via the change valve 52 as in the case described above. The hydraulic pressure in the master cylinder 14 does not rise and the control valve
This is because it is lower than the output hydraulic pressure of 30.

Next, the operation when the electromagnetic hydraulic pressure control device fails will be described.

In this case, when the brake pedal 10 is operated, the output hydraulic pressure of the master cylinder 14 rises, but the output hydraulic pressure of the control valve 30 does not rise, and the first chamber 68 of the change valve 52 shown in FIG.
Due to the output hydraulic pressure of the master cylinder 14 supplied to the control piston 62, the control piston 62 retracts and the on-off valve 82 closes. As a result, the supply of the hydraulic fluid from the control valve 30 to the rear wheel cylinder 32 is cut off, and the output hydraulic pressure of the master cylinder 14 is allowed to be transmitted to the rear wheel cylinder 32. Is increased according to the output hydraulic pressure of the master cylinder 14.

In this state, if the wheel cylinder side passage 56 or the rear wheel cylinder 32 itself fails, the liquid in the third chamber 72 will leak, but the first chamber 68, the second chamber 70, and the third chamber 72 are mutually Since it is blocked by the control piston 62, the cup seal 74 and the housing 58, the liquid in the master cylinder 14 is prevented from leaking. Therefore,
After the control piston 62 reaches the retracted end position by the hydraulic pressure of the first chamber 68, that is, the output hydraulic pressure of the master cylinder 14, the master cylinder 14 can be boosted, and the front wheel cylinder 18 operates the brake pedal 10 with an operating force. A brake fluid pressure of a height corresponding to is generated.

From the above state, if the operation of the brake pedal 10 is released, the determination result in S3 of FIG. 2 becomes NO, the initial flag is reset in S1, and the pressure reducing command is issued to the control valve 30 in S2 to cause the rear liquid. As the pressure decreases, the front hydraulic pressure also decreases.

As is clear from the above description, in this embodiment,
The change valve 52, which is a transfer switching valve, and the liquid passage 50 constitute a transfer switching device.
The reference numeral 82 functions as a shut-off means when liquid leakage occurs on the side of the control valve 30 which is the electromagnetic hydraulic pressure control device, and the control piston 62 of the change valve 52, the cup seal 74 and the housing 58.
Is the rear wheel cylinder 32, which is the second brake cylinder.
It functions as a shut-off means when liquid leakage occurs on the side.

Even if the control valve hydraulic pressure source of the electromagnetic hydraulic pressure control device fails, the operation of the front and rear brakes is ensured as described above. However, in the present embodiment, the control valve hydraulic pressure source is hydraulic pressure. Since it also serves as the hydraulic pressure source of the booster 12, it is possible to prevent the boosting action of the hydraulic booster 12 from being obtained due to a failure of the hydraulic pressure source for the control valve, and as a result, it is possible to avoid increasing the required operating force of the brake pedal 10. I don't get it. When it is necessary to avoid such a situation, the hydraulic pressure source of the hydraulic pressure booster 12 may be provided separately from the control valve hydraulic pressure source.

The above explanation is for the case where the main power supply of the vehicle is normal. However, even when this main power supply fails, the operation of the front and rear brakes is the same as when the control valve hydraulic pressure source fails. Is secured. If the hydraulic pressure supply device is of a type that electromagnetically controls the front hydraulic pressure, both brakes may become inoperable due to a failure of the main power supply. However, in this embodiment, the front hydraulic pressure is mechanically generated by the master cylinder 14 in accordance with the brake operating force, so that the operation of both brakes is secured even if the main power source fails. .

In this embodiment, the control of the rear hydraulic pressure by the control valve 30 is performed based on the actual rear hydraulic pressure. Although the so-called feedback control is performed, the rear hydraulic pressure control may be an open loop control in which the computer 92 unilaterally supplies a predetermined signal to the solenoid control circuit 104 according to the target value of the rear hydraulic pressure. . In this case, the rear hydraulic pressure sensor 100 can be omitted, and the effect of reducing the device cost can be obtained.

Further, a proportioning valve can be provided in the middle of the liquid passage 50 connecting the master cylinder 14 (or the first pressurizing chamber 140 of the tandem type master cylinder 130) and the change valve 52 (or the shuttle valve 142). This makes it possible to prevent early locking of the rear wheels at the conventional level even when the electromagnetic hydraulic pressure control device has failed.

Further, in the present embodiment, it is determined that the electromagnetic hydraulic pressure control device is out of order, the output hydraulic pressure of that is compared with the output hydraulic pressure of the hydraulic pressure supply device, and the former is lower than the latter. The determination is made by comparing the height of the output hydraulic pressure of the electromagnetic hydraulic pressure control device with a predetermined reference value, or the excitation command signal of the computer 92 and the solenoid of the control valve 30. It can be performed by a method according to the detection purpose, such as comparing with the exciting current. In these cases, if the transfer switching valve is an electromagnetic valve and the transfer state is switched electrically, the output hydraulic pressure of the electromagnetic hydraulic pressure control device will be the hydraulic pressure when the electromagnetic hydraulic pressure control device is normal. No need to set higher than the output fluid pressure of the supply device,
The degree of freedom in controlling the output hydraulic pressure is improved.

In addition, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a system diagram of a hydraulic brake device including a brake hydraulic pressure control device according to an embodiment of the present invention, FIG. 2 is a front sectional view showing a change valve in the above embodiment, and FIG. 6 is a flowchart showing a program for determining and controlling the rear wheel cylinder hydraulic pressure in the above embodiment. FIG. 4 is a graph showing the relationship between the front wheel cylinder hydraulic pressure, the rear wheel cylinder hydraulic pressure, and the rear wheel load in the above embodiment. 10: Brake pedal, 12: Hydraulic booster, 14: Brake master cylinder, 18: Front wheel cylinder, 22: Accumulator, 30: Spool type proportional electromagnetic hydraulic control valve, 32: Rear wheel cylinder, 52: Change valve, 92 : Computer, 98: Front hydraulic pressure sensor, 100: Rear hydraulic pressure sensor, 1
02: Rear wheel load sensor

Claims (1)

[Scope of utility model registration request] 1. A first output hydraulic pressure having a height corresponding to an operation amount of an operation member, an operation amount such as an operation stroke, etc. is generated, and the first output hydraulic pressure is applied to either a front wheel or a rear wheel of a vehicle through a first liquid passage. A hydraulic pressure supply device for supplying to the first brake cylinder corresponding to one side, and a hydraulic pressure of a hydraulic pressure source is controlled to a height according to an operation amount of the operating member to obtain a second output hydraulic pressure, and a second output thereof. An electromagnetic hydraulic pressure control device for supplying hydraulic pressure to a second brake cylinder corresponding to one of the front wheel and the rear wheel, which is not the other, by means of a second hydraulic passage, and an electromagnetic hydraulic pressure control device provided in the middle of the second hydraulic passage. By the third liquid passage,
Even when liquid leakage occurs in the pressure holding portion of the hydraulic pressure supply device from the electromagnetic hydraulic pressure control device to the second brake cylinder, the hydraulic pressure supply device is connected to a pressure chamber that generates the first output hydraulic pressure, and a brake operation is performed. In this state, the second output hydraulic pressure of the electromagnetic hydraulic pressure control device is always transmitted to the second brake cylinder, but when the electromagnetic hydraulic pressure control device fails, the first output hydraulic pressure of the hydraulic pressure supply device is changed. A transmission switching device for transmission, and when a fluid leaks from the hydraulic pressure supply device due to a failure of at least one of the electromagnetic hydraulic pressure control device and the second brake cylinder provided in the transmission switching device, transmission is performed. A brake fluid pressure control device including a shutoff means for shutting off the flow of fluid from the switching device to the at least one.