JP2001322539A - Vehicular braking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a braking distance in the case when a stroke simulator for changing (expanding) the volume by the fluid pressure, of a master cylinder is provided. SOLUTION: An accumulator 28 is provided for accumulating brake fluid pressure of high pressure besides a master cylinder 21. The stroke simulator 38 is arranged for expanding the volume by receiving the master cylinder fluid pressure. Valves MCV1 and MCV2 are usually closed, and accumulator fluid pressure is supplied to brake devices 31FL to 31RR (a wheel cylinder) by opening a VLV1 and a VLV2. When a brake fluid pressure sensor S1 to S5 cause failure, the opening-closing relationship between the valves is reversed so that the master cylinder fluid pressure is supplied to the wheel cylinder. At this time, an opening-closing valve 39 is closed to cut off supply of the master cylinder fluid pressure to the stroke simulator 38. The accumulator fluid pressure can be supplied to the back side of the stroke simulator 38 to restrain the volume change.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle braking device.

[0002]

2. Description of the Related Art In a braking device for a vehicle, in addition to a first hydraulic pressure generation source (master cylinder) for generating a brake hydraulic pressure in response to a driver's braking operation, a driver's braking operation is also included. In some cases, a second hydraulic pressure source for generating a high brake hydraulic pressure is provided independently. In this case, a wheel cylinder of a brake device for braking the vehicle is selectively connected to the first hydraulic pressure source and the second hydraulic pressure source by the switching means. In other words, under a predetermined condition set in advance, for example, when performing automatic braking or emergency braking, a desired braking force is obtained by using the high brake fluid pressure generated by the second hydraulic pressure source. On the other hand, at other times, braking using the first hydraulic pressure generation source is performed. Even during braking using the second hydraulic pressure generation source, the driver often performs the brake operation, and the first hydraulic pressure generation is performed so that the brake operation feeling at this time, in particular, the brake stroke can be properly obtained. In some cases, a stroke simulator whose volume is changed by receiving a brake fluid pressure from a source is provided (JP-A-11-48950).
Reference).

[0003]

By the way, it is conceivable that a failure occurs in the brake system and braking is performed using the brake hydraulic pressure from the first hydraulic pressure generation source. Normally, braking at this time requires urgency. However, if the above-described stroke simulator is provided, the brake hydraulic pressure generated by the first hydraulic pressure generation source is also affected by a change in the volume of the stroke simulator. There is room for improvement in that it is consumed and that quick braking is achieved, that is, the braking distance is shortened.

The present invention has been made in view of the above circumstances, and has as its object to provide a stroke simulator in which a volume is changed by receiving a brake fluid pressure generated by a brake operation by a driver. It is an object of the present invention to provide a vehicle braking device capable of shortening a braking distance when a failure occurs in a brake system.

[0005]

In order to achieve the above-mentioned object, the present invention adopts the following solution. That is, as described in claim 1 of the claims, a first hydraulic pressure source that generates a brake hydraulic pressure in response to a driver's braking operation, and a second hydraulic pressure source that generates a high brake hydraulic pressure A hydraulic pressure source and a wheel cylinder of a brake device for braking a vehicle are connected to the first hydraulic pressure source and a second hydraulic pressure source.
Switching means for selectively communicating with a hydraulic pressure source;
A stroke simulator that changes its volume in response to a brake fluid pressure from the first hydraulic pressure source, and a suppression unit that suppresses a change in the volume of the stroke simulator when a failure occurs in a brake system. There is. Preferred embodiments on the premise of the above solution are as described in claim 2 and the following claims.

[0006]

According to the first aspect of the present invention, when a failure occurs in the brake system, the change in the volume of the stroke simulator is suppressed. The generated brake fluid pressure is sufficiently supplied, and the braking distance is shortened.

According to the second aspect of the present invention, the first
The supply of the brake hydraulic pressure from the hydraulic pressure generation source to the stroke simulator is completely shut off, that is, the function of the stroke simulator is completely stopped, and the effect corresponding to claim 1 can be sufficiently exhibited. .

According to the third aspect of the present invention, the second
The change in volume of the stroke simulator can be suppressed by effectively using the high pressure generated by the hydraulic pressure generation source.

According to the invention described in claim 4, the effect corresponding to claim 3 can be exhibited even when the brake fluid pressure stored in the accumulator is small.

According to the invention described in claim 5, the same effect as in claim 1 can be obtained by minimizing the volume change of the stroke simulator for the same brake stroke.

[0011]

FIG. 1 shows an example of a brake (braking) circuit. In FIG. 1, reference numeral 21 denotes a master cylinder as a first hydraulic pressure generation source that generates a brake hydraulic pressure in accordance with the operation amount (depressed amount) of the brake pedal 22. Further, a pump device 23 is provided as a second hydraulic pressure generation source. The pump device 23 includes two pumps 2
4 and one motor 25 for driving the pump 24. Each pump 24 sucks brake fluid from the reservoir tank 21 a of the master cylinder 21 via a check valve 26 and discharges high-pressure brake fluid to an accumulator 28 via a check valve 27. Excess brake fluid discharged from the pump 24 is returned to the reservoir tank 21a via the check valve 29. The brake fluid stored in the accumulator 28 is supplied to the reservoir 30 after being adjusted to a desired pressure by the linear solenoid valve LSV.

The brake devices provided on the respective wheels, that is, the friction brake devices that perform braking by frictional force are all disc brakes in the embodiment, the left front wheel brake device is denoted by reference numeral 31FL, and the right front wheel brake device is Code 3
1FR, the left rear wheel brake device is denoted by 31RL.
, And the brake device for the right rear wheel is indicated by reference numeral 31RR. Each brake device (wheel cylinder) 31FL
To 31RR, brake fluid pressure is supplied via the ABS control circuit 32. That is, the ABS control circuit 32
It has two connecting parts 33 and 34, and for the connecting part 33, the brake fluid from the master cylinder 21 via the MCV1 consisting of an electromagnetic on-off valve and the VLV1 consisting of an electromagnetic on-off valve are provided. And the brake fluid from the reservoir 30 are selectively supplied. Similarly, for the connection portion 34, the brake fluid from the master cylinder 21 via the MCV2 comprising an electromagnetic on-off valve and the brake fluid from the reservoir 30 via the VLV2 comprising an electromagnetic on-off valve are provided. Are selectively supplied. An electromagnetic opening / closing valve 42 is connected to a passage 41 extending from the reservoir 30 to the reservoir 21a of the master cylinder 21. The on-off valve 42 is closed when the brake fluid pressure is supplied from the pump device 23 to the wheel brake device via the linear solenoid valve LSV, and is opened otherwise.

The ABS control circuit 32 has a supply valve and an exhaust valve each composed of an electromagnetic on-off valve for each brake device. That is, the brake fluid from the connection portion 33 is supplied to the supply valve 35FL.
Is supplied to the left front wheel brake device 31FL via the supply valve 35RR, and is supplied to the right rear wheel brake device 31RR via the supply valve 35RR. Similarly, the brake fluid from the connecting portion 34
Right front wheel brake device 31FR via supply valve 35FR
And supplied to the left rear wheel brake device 31RL via the supply valve 35RL. Further, the brake fluid is discharged from each of the brake devices 31FL to 31RL during the ABS control independently through the discharge valves 36FL to 36RR. In FIG. 1, reference numerals 37FL to 37RR denote check valves provided in each of the brake devices to bypass the supply valve 35 and immediately discharge the brake fluid.

A stroke simulator 38 is connected to a brake passage extending from the master cylinder 21 to the on-off valve MCV1. This stroke simulator 38
As will be described later, the volume is changed according to the magnitude of the brake fluid pressure generated in the master cylinder 21 (securing the stroke of the brake pedal 22). Further, between the master cylinder 21 and the stroke simulator 38, an electromagnetic on-off valve 39 for suppressing a change in volume of the stroke simulator 38 is connected as described later.

In FIG. 1, S1 to S5 are pressure sensors.
That is, the sensors S1 and S2 independently detect the hydraulic pressure generated in the master cylinder 21 having two systems. The sensors S3 and S4 independently detect the hydraulic pressures of the two wheel cylinders. The sensor S5 detects the pressure stored in the accumulator 28.

FIG. 2 shows an example of the stroke simulator 38. This stroke simulator 38
Has first and second two pistons 52 and 53 slidably fitted in a main body casing 51, and first and second two return springs 54 and 55, respectively. The two pistons 52 and 53 are arranged in series with each other, and an oil chamber 56 is defined on the left side of the first piston 52 in the drawing, and the oil chamber 56 is connected to the master cylinder 21 via the on-off valve 39. Connected. A first return spring 54 is provided between the two pistons 52 and 53, and a second return spring 55 is provided on the right side of the second piston 53. The first return spring 53 urges the first piston 52 in a direction in which the oil chamber 56 is compressed. Also, the second
The return spring 55 urges the first piston 52 via the second piston 53 and the first return spring 53 in a direction in which the oil chamber 56 is compressed. The rear side of each of the pistons 52 and 53 opposite to the oil chamber 56 is connected to the reservoir 21a of the master cylinder 21 (drain).

The urging force of the second return spring 55 is set to be larger than the urging force of the first return spring 54. Thus, the relationship between the brake stroke and the change in the volume of the oil chamber 56 (the amount of volume increase) is as shown in FIG. That is, as the brake stroke, that is, the generated brake fluid pressure in the master cylinder 21 increases, first, the first piston 52 is displaced rightward in FIG. 2 only against the first return spring 54 (brake). After the first piston 52 contacts the second piston 53, the first piston 52 is displaced rightward in FIG. 2 against the return spring 55. (Small volume change relative to brake stroke).

FIG. 4 shows a control system for braking control, where U is a controller (control unit) constructed using a microcomputer. The controller U receives signals from the pressure sensors S1 to S5 described above and also receives a signal from a stroke sensor S6 for detecting a brake stroke (in this embodiment, the stroke of the brake pedal 22 is directly detected). ). Also,
From the controller U, the various valves MCV1,
MCV2, VKV1, VKV2, LSV, pump /
A control signal is output to the motors 24 and 25, and the fuel lamp 40 is operated when a brake system failure described later occurs.

Next, the braking control by the controller U will be described with reference to the flowchart of FIG. 5. In the following description, Q indicates a step. In the embodiment,
Normally, a braking force is obtained by using a brake fluid pressure from a pump device 23 as a second fluid pressure source, and a brake fluid pressure from a master cylinder 22 as a first fluid pressure source is supplied to a brake system. At the time of failure (emergency)
Only used for The opening / closing valve 29 is initially opened, and is closed only when a failure occurs in the brake system as described later.

First, in Q1 of FIG. 5, various sensors S
After the signals from 1 to S6 are input, it is determined in S2 whether a failure has occurred in the brake system. In the embodiment, the devices to be subjected to the failure determination and the failure determination method are as follows. First, with respect to the accumulator pressure detecting sensor S5, when the increase rate of the pressure detected by the sensor S5 is smaller than a predetermined value in a state where the motor 25 is driven and the LSV is closed, the sensor S5 fails. Is determined. When the deviation between the detected values of the master cylinder pressure detecting sensors S1 and S2 is larger than a predetermined value, the sensor S1 or S2
2 is determined to be faulty. When the deviation between the respective detection values of the wheel cylinder pressure detection sensors S3 and S4 is equal to or greater than a predetermined value, it is determined that the sensor S4 or S5 is unique. Regarding the LSV, when the wheel cylinder pressure (the value detected by the sensors S4 and S5) with respect to the control target value is abnormal, it is determined that the LSV has failed.

When the determination of Q2 is NO (normal)
In Q3, MCV1 and MCV2 are closed, and VLV1 and VLV2 are opened. Then
In Q4, it is determined whether or not emergency braking is being performed.
Specifically, the determination of the emergency braking in Q4 is made when the master cylinder pressure (the pressure detected by the sensors S1 and S2) is equal to or higher than a predetermined value and the rate of change of the master cylinder pressure in the rising direction is equal to or higher than the predetermined value. It is assumed that emergency braking is being performed. If the determination in Q4 is NO, in Q5, it is determined whether the brake stroke detected in S6 is equal to or less than a predetermined value, that is, whether the brake stroke is within the range of the stepping allowance of the brake pedal 22. If the determination in Q5 is NO, it means that there is no longer any stepping allowance for depressing and displacing the brake pedal 22, and in this case, in Q6, the wheel cylinder pressure is reduced to the target control pressure (in accordance with the master cylinder pressure). LS so that the target control value
V is controlled (feedback control). When the determination in Q5 is YES, that is, when the brake pedal 22 is still in the range where the brake pedal 22 can be depressed and displaced, the LSV is controlled such that the wheel cylinder pressure becomes the target control pressure corresponding to the brake stroke ( Feedback control).

After Q6 or Q7, it is determined in Q8 whether the accumulator pressure is equal to or lower than a predetermined value. If the determination in Q8 is YES, Q9
, The pump 25 is operated to increase the accumulator pressure. If NO in Q8, Q10
In, the motor 25 is stopped.

If the determination in Q4 is YES, it means that the emergency braking is being performed, and in Q11, a predetermined increase coefficient K (K> K) is applied to the master cylinder pressure in order to set the wheel cylinder pressure to a sufficiently large value. The LSV is controlled so that the target control pressure is set according to the value obtained by multiplying 1) (feedback control).

If the determination in Q2 is YES, it means that a failure has occurred in the brake system. In this case, Q1
At 2, MCV1 and MCV2 are opened, and VLV1 and VLV2 are closed. Then, Q1
At 3, the on-off valve 39 is closed.

The above-described process of shifting to Q3 is a brake fluid pressure control using LSV, and therefore, MCV1 and MCV2 are closed in Q3. This MCV1, MC
When V2 is closed, the volume of (the oil chamber 56 of) the stroke simulator 38 is expanded by receiving the master cylinder pressure generated in response to the depression of the brake pedal 22, thereby causing the brake pedal 22 to fully stroke. Becomes possible, and the brake operation feeling is improved.

FIGS. 6 and 7 show a second embodiment of the present invention. FIG. 6 is an essential hydraulic circuit showing only parts different from FIG. 1, and FIG. 6 is a main part flowchart showing only parts different from FIG. In the present embodiment, the volume change of the stroke simulator 38 when a failure occurs in the brake system is suppressed by supplying a high-pressure accumulator pressure to the back side of the piston, so that the volume of the stroke simulator 38 does not substantially change. (So as not to increase the volume). That is, the piston back side of the stroke simulator 38 is selectively communicated with the accumulator 28 and the reservoir 21a of the master cylinder by the electromagnetic switching valve 61 controlled by the controller U. When the one shown in FIG. 2 is used as the stroke simulator 38, the first piston 52 and the second piston 53
At least one back side (the side opposite to the oil chamber 56)
May be set so as to selectively communicate with the accumulator 28 or the reservoir 21a (when the accumulator pressure is received, the first piston 52 is fixed to the left end position shown in FIG. Not to be enlarged).

As shown in FIG. 7, when a failure occurs in the brake system, the processes of Q22 to Q26 are performed in place of Q12 and Q13 of FIG. 5 (other controls are the same as those of FIG. 5). the same). That is, if it is determined in Q2 that a failure has occurred in the brake system, in Q22, MC
V1 and MCV2 are opened, and VLV1 and VL
V2 is closed. Next, in Q23, the switching valve 61 is switched so that the stroke simulator 38 (on the rear side) communicates with the accumulator 28. Thereafter, in Q24, it is determined whether the accumulator pressure is equal to or less than a predetermined value. In the determination of Q24, YE
In the case of S, the pump 25 is operated in Q25 to increase the accumulator pressure. If NO in Q24, the motor 25 is stopped in Q26. By the processing from Q24 to Q26, suppression of the volume change of the stroke simulator 38 using the accumulator pressure is reliably ensured.

FIGS. 8 to 13 show a third embodiment of the present invention, which suppresses a change in volume (increase in volume) of (the oil chamber 56 of) the stroke simulator 38 when a failure occurs in the brake system. Is obtained by increasing the resistance of the stroke simulator 38 to the brake stroke, that is, the brake fluid pressure. First, the principle of the present embodiment will be described with reference to FIG. 8. Reference numeral 71 denotes a cylinder portion having a piston 73 that defines an oil chamber 72 (corresponding to the oil chamber 56 in FIG. 2) that receives a master cylinder pressure. . An elongated connecting member 74 is integrated with the piston 73. This connecting member 74 is
It is connected to a spring mechanism 78 via a link 75, a swing lever 76, and a second link 77.

The spring mechanism 78 includes a cylinder 81, a movable member 82 and a spring seat member 83 disposed therein.
And a return spring 84 is disposed between the two 82 and 83. The spring seat member 83 is screwed to a screw rod 85 that is rotatable with respect to the cylinder 81 and is not displaceable in the axial direction. It can be displaced in the cylinder 81 (the relative distance to the movable member 82 is variable). In the spring mechanism 78, the return spring 84 abuts against the movable member 82 and the spring seat member 83 so that the spring seat member 8
Position 3 is set.

The swing lever 76 is swingable about a fulcrum 76a. One end of the first link 75 is rotatably connected to one end of the connecting member 74 about a fulcrum 75a, and the other end of the first link 75 is
The swing lever 76 is rotatably connected to a tip end of the swing lever 76 about a fulcrum 75b. As will be described later, a slider 91 is attached to the swing lever 76 so as to be displaceable in the longitudinal direction of the swing lever 76, and the position of the slider 91 is changed by a motor 92 as described later. One end of a second link 77 is rotatably connected to the slider 91 about a fulcrum 77a, and the other end of the second link 77 is connected to a movable member 82 of a spring mechanism 78.
, Are rotatably connected around a fulcrum 77b.

When the master cylinder pressure acts on the oil chamber 72 of the cylinder portion 71, the piston 73 is displaced rightward in FIG. 8, and this displacement is caused by the first link 75, the swing lever 76, and the second link 77. 8 acts as a force for displacing the movable member 82 of the spring mechanism 78 rightward in FIG. The displacement of the movable member 82 to the right in FIG. 8 is resisted by the return spring 84, and this resisting force becomes a reaction force from the spring mechanism 78 accompanying the increase in the volume of the oil chamber 72. The magnitude of the reaction force (resistance force) of the spring mechanism 78 that opposes the force received by the piston 73 due to the master cylinder pressure is the first length L that is the length from the fulcrum 76a to the fulcrum 75b.
It is determined by a lever ratio which is a ratio of 1 to a second length L2 which is a length from the fulcrum 76a to the fulcrum 77a. Therefore, if the lever ratio is changed by changing the position of the slider 91, the resistance by the spring mechanism 78 is changed (substantial change in the spring constant of the return spring 84).

In order to change the resistance using the spring mechanism 78 in two stages, the first link 75, the swing lever 76,
Two sets of the second link 77, the spring mechanism 78, and the like are provided. As for the second set, those corresponding to the elements from 75 to 92 have B
8 (part of components corresponding to the second set of spring mechanisms is not shown). This second set is
It is arranged in parallel with the first set in the direction perpendicular to the paper surface.
In the second set of spring mechanisms 78B, in the initial state, the movable member 82B and the return spring 84B are separated by a predetermined distance α, and the urging force of the return spring 84B is larger than the urging force of the return spring 84. It is assumed. Thus, when the piston 73 is displaced rightward in FIG. 8 by receiving the master cylinder pressure, a reaction force is initially generated only by the spring mechanism 78, but a large reaction force is generated from the middle by the spring mechanism 78B. You. FIG. 9 shows a characteristic line indicating the relationship between the brake stroke (master cylinder pressure) and the reaction force (resistance) when the second set of spring mechanisms 78B is provided. By changing the positions of both sliders 91 (91B is not shown), the state shown by the solid line and the state shown by the broken line in FIG. 9 can be changed as appropriate. Of course, the case indicated by the broken line indicates a case where the reaction force is large.

In order to suppress a change in the volume of the stroke simulator 38 when the brake system fails, the slider 9 is controlled so that the reaction force of the spring mechanisms 78 and 78B is maximized.
1 (91B not shown) is changed (Q1 in FIG. 2).
Control corresponding to 3). Of course, the controller U is provided with a motor 92 for changing the position of the slider 91 (91B not shown).
(Not shown, 92B). Motor 8
6 and 86B change the positions of the spring seat members 83 and 83B so that the desired characteristics shown in FIG. 9 can be obtained by changing the position of the slider 91 (91B not shown).
It is controlled by the controller U.

FIGS. 10 and 11 show the spring mechanism 78 described above.
It shows a specific example of the above. A projection 83a is formed on the outer peripheral surface of the spring seat member 83 so as to protrude, while a guide groove 81a extending in the axial direction is formed on the inner surface of the cylinder 81, and the projection 83a is slidable in the guide groove 81a. And the rotation of the screw rod 85 is prevented (co-rotation of the spring seat member 83 with rotation of the screw rod 85). Screw rod 85
Is held rotatably with respect to the cylinder 81 and cannot be displaced in the axial direction. Then, the spring seat member 83 is screwed to the screw rod 85, and the spring seat member 83 is displaced in the axial direction of the cylinder 81 with the rotation of the screw rod 85.

FIGS. 12 and 13 show specific examples of the swing lever 76 portion. That is, the swing lever 76
Is swingable about a fulcrum 76a with respect to a holder 95 serving as a fixing member. A screw rod 96 is held by the swing lever 76 so as to be rotatable and non-displaceable in the longitudinal direction (axial direction).
Is screwed. Thus, by rotating the screw rod 96 by the motor 92, the slider 91 is displaced in the longitudinal direction of the swing lever 76.

FIG. 14 shows a fourth embodiment of the present invention, in which the brake control using the LSV is executed at the time of automatic braking performed to avoid collision with an obstacle ahead. . Note that FIG. 14 shows only steps different from those in FIG. 5, and the other controls are the same as those in FIG. 5. That is, in Q34 (Q in FIG. 5)
4), it is determined whether or not the automatic braking is required. Specifically, for example, when the vehicle deceleration required to set the headway time to the front obstacle (the time to reach the front obstacle) as a target value is equal to or greater than a predetermined value, and when automatic braking is required. It is determined that there is. If the determination in Q34 is NO, the same processing as in Q5 and thereafter in FIG. 5 is performed. If the determination in Q34 is YES, the LSV is controlled in Q31 (corresponding to Q11 in FIG. 5) such that the wheel cylinder pressure becomes a control target value corresponding to the vehicle deceleration (feedback control). The control target value (target brake fluid pressure) is set to increase as the vehicle deceleration increases. Note that a radar that detects the distance to the obstacle ahead is used to calculate the above-mentioned headway time, and the detection distance of this radar is input to the controller U.

Although the embodiment has been described above, the conditions for selecting whether the brake fluid pressure introduced into the wheel cylinder should be the high brake fluid pressure from the accumulator 28 or the brake fluid pressure from the master cylinder 21 are appropriately determined. It can be set. Stroke simulator 38
May have only one piston (return spring). The swing lever 76 and the spring mechanism 78 shown in FIG.
Only one set may be used (the characteristic line in FIG. 9 is almost linear),
Alternatively, there may be three or more sets (the characteristic line in FIG. 9 has three or more break points). Each step (step group) shown in the flowchart or various members such as a sensor and a switch can be expressed by adding a name of a means to a higher-level expression of its function. In addition, the object of the present invention is not limited to what is explicitly specified, but also implicitly includes providing what is expressed as substantially preferable or advantageous. Further, the present invention can be expressed as a control method.

[Brief description of the drawings]

FIG. 1 is a brake circuit diagram showing an example of a brake system.

FIG. 2 is a sectional view showing an example of a stroke simulator.

FIG. 3 is a view showing characteristics of the stroke simulator shown in FIG. 2;

FIG. 4 is a block diagram showing an example of a control system according to the present invention.

FIG. 5 is a flowchart showing a control example of the present invention.

FIG. 6 is a main part brake circuit diagram in a case where the volume change of the stroke simulator is suppressed using the accumulator pressure.

FIG. 7 is a main part flowchart showing a control example in the case of FIG. 6;

FIG. 8 is a simplified explanatory view showing an example of a mechanism that makes the resistance of a stroke simulator variable.

FIG. 9 is a diagram showing resistance force characteristics of a stroke simulator when two sets of spring mechanisms are provided.

FIG. 10 is a side sectional view showing a specific example of the spring mechanism shown in FIG. 8;

11 is a cross-sectional view corresponding to line X11-X11 in FIG.

FIG. 12 is a plan view showing a specific example of a swing lever portion shown in FIG. 8;

FIG. 13 is a sectional view taken along line X13-X13 in FIG. 112;

FIG. 14 is a main part flowchart showing an example of brake fluid pressure control during automatic braking.

[Explanation of symbols]

21: Master cylinder 21a: Reservoir 22: Brake pedal 23: Pump device (high-pressure brake fluid pressure generating source) 28: Accumulator 31FL-31RR: Brake device 38: Stroke simulator 39: Open / close valve (for suppressing volume change) 52, 53 : Piston 54: 55: return spring 56: oil chamber 72: oil chamber 73: piston 74: connecting member 75: first link 76: swing lever 76 a: swing fulcrum 77: second link 78: spring mechanism 78B: 2 Spring mechanism of the set 82: Movable member 83: Spring seat member 84: Return spring 85: Screw rod 86: Motor 91: Slider (for variable resistance) 92: Motor (for variable resistance) 96: Screw rod MCV1, MCV2 : Switching valve (for selecting master cylinder and accumulator) VLV1, VLV2 Switching valve (for selection of the master cylinder and the accumulator) LSV: linear solenoid valve (for adjusting the brake fluid pressure) S1-S5: pressure sensor S6: stroke sensor U: Controller - La

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Akira Iyoda 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture F-term (reference) 3D046 BB01 BB03 BB18 BB28 HH16 LL00 LL02 LL23 LL37 LL41 MM06

Claims (5)

[Claims] 1. A first hydraulic pressure source for generating a brake hydraulic pressure in response to a driver's brake operation, a second hydraulic pressure source for generating a high brake hydraulic pressure, and a brake for braking a vehicle Switching means for selectively communicating a wheel cylinder of the device with the first hydraulic pressure source and the second hydraulic pressure source; and receiving a brake hydraulic pressure from the first hydraulic pressure source to change the volume. A braking device for a vehicle, comprising: a stroke simulator to be operated; and a suppression unit that suppresses a change in volume of the stroke simulator when a failure occurs in a brake system. 2. The apparatus according to claim 1, wherein said suppressing means is set to cut off communication between said first hydraulic pressure generation source and a stroke simulator when a failure occurs in a brake system. Vehicle braking device. 3. The stroke simulator according to claim 1, wherein the stroke simulator has a piston defining an oil chamber that communicates with the first hydraulic pressure generation source, and is urged in a direction to compress the oil chamber via the piston. And a suppressor for introducing a high pressure from the second hydraulic pressure generation source to a rear side of the piston opposite to the oil chamber when a failure occurs in a brake system. A braking device for a vehicle, which is set as follows. 4. The apparatus according to claim 3, wherein the second hydraulic pressure generation source includes an accumulator for accumulating high-pressure brake fluid, and a pump for accumulating brake fluid from a reservoir in the accumulator, A brake system for a vehicle, wherein the pump is set to operate when the pressure of the accumulator is low when a failure occurs in a brake system. 5. The apparatus according to claim 1, further comprising: a resistance varying means for varying a resistance of the stroke simulator to a change in volume, wherein the suppressing means has a maximum value when a failure occurs in a brake system. The braking device for a vehicle is set so as to control the resistance varying means as described above.