JPH05310112A - Brake device for vehicle - Google Patents

Abstract

PURPOSE:To prevent a state wherein an automatic brake is being applied due to trouble in applying automatic braking such as traction control, etc. CONSTITUTION:Brake fluid pressure from a pump 37 is applied to the fluid chamber 13 of a pressurizing piston 12 to pressurize brake fluid in a piping 6 extending from a master cylinder 1, by making a directional control valve 32 a fluid pressure supply condition (automatic brake condition). Automatic brake can be surely released even the directional control valve 32 is fixed in the fluid pressure supply condition with a switch valve 44 opened when brake fluid pressure in the fluid chamber 13 is released.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Generally, a vehicle brake device is
The brake cylinder is equipped with a master cylinder in which a brake hydraulic pressure is generated when a driver depresses a brake pedal, and the brake hydraulic pressure generated in the master cylinder is applied to a wheel through a brake pipe. -The braking is performed by being supplied to the key device.

As described above, the braking of the vehicle is usually governed by the will of the driver. However, recently, regardless of the intention of the driver, braking is performed when a predetermined condition is satisfied, that is, automatic braking is performed. The number of vehicles that perform braking is increasing. For example, there is a so-called traction control or slip control that automatically applies a braking force to a drive wheel when the drive wheel excessively rotates during acceleration (see Japanese Patent Laid-Open No. 2-274649). Further, as is known by the name of a rear-end collision prevention device, there is a device that automatically brakes when it is detected that the vehicle is too close to the preceding vehicle.

As described above, in the automatic braking system, in addition to the first hydraulic pressure generating means for generating the brake hydraulic pressure by the brake operation of the driver, for example, it is driven by the engine. The second brake hydraulic pressure generating means is provided for generating the brake hydraulic pressure regardless of the driver's intention by using the pump. A pressurizing piston for pressurizing the brake fluid in the first hydraulic pressure path connecting the first brake hydraulic pressure generating means and the brake device for vehicle braking is provided, and the pressurizing piston is provided. By applying the brake fluid pressure generated by the second brake fluid pressure generating means to the piston, the brake fluid in the first fluid pressure path is pressurized to perform automatic braking. Is becoming

The supply of the brake hydraulic pressure to the pressurizing piston (at the time of automatic braking) and the release (at the time of releasing automatic braking) are switched by a switching valve. That is, the brake generated by the second brake hydraulic pressure generating means is generated by the switching valve.
A hydraulic pressure supply mode of supplying the hydraulic pressure to the pressurizing piston and a hydraulic pressure releasing mode of releasing the brake hydraulic pressure acting on the pressurizing piston to the reservoir tank are switched.

[0006]

By the way, in the automatic brake device as described above, the switching valve remains stuck in the hydraulic pressure supply state due to some cause, and the brake is not used. It is conceivable that the key will be left on, that is, it will be held in the state of the automatic brake. In this way, if the automatic brake state is maintained, the running of the vehicle will be supported, and some measures will be required.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a brake device for a vehicle which can prevent the automatic brake state from being continuously maintained due to a failure.

[0008]

In order to achieve the above object, the present invention has the following structure, that is, a brake hydraulic pressure is generated by a brake operation by a driver. A first hydraulic pressure generating means, a first hydraulic pressure path for supplying the brake hydraulic pressure generated by the first hydraulic pressure generating means to a braking device of a vehicle, and a brake operation by a driver. Second hydraulic pressure generating means for generating a brake hydraulic pressure independently of each other, and a brake hydraulic pressure in the first hydraulic pressure path when the brake hydraulic pressure generated by the second hydraulic pressure generating means is received. A pressurizing piston that pressurizes the brake fluid to activate the brake device;
A hydraulic pressure supply mode for supplying the brake hydraulic pressure generated by the second hydraulic pressure generating means to the pressurizing piston and the brake hydraulic pressure acting on the pressurizing piston is released to the reservoir tank. A switching valve for switching between hydraulic pressure releasing modes, a bypass passage for releasing the brake hydraulic pressure acting on the pressurizing piston to the reservoir tank by bypassing the switching valve, and the bypass passage. And an on-off valve connected to.

For determining the failure of the switching valve, for example, the following configuration can be adopted. That is, when the pressure detecting means for detecting the brake fluid pressure acting on the pressure piston and the brake fluid pressure from the second brake fluid pressure generating means are applied to the pressure piston. A delay means for switching the switching valve to the hydraulic pressure supply mode by delaying after closing the switching valve; and a delay means for switching the switching valve to the hydraulic pressure supply mode after the switching valve is closed. Up to the above, it is possible to further include a failure determination means for performing failure determination of the switching valve according to the magnitude of the brake fluid pressure detected by the pressure detection means.

When the failure determination means determines that the switching valve has a failure, failure handling means for forcibly holding the open / close valve in the open state may be further provided.

Further, the following structure can be used for determining the failure of the on-off valve. That is, pressure detecting means for detecting the brake fluid pressure acting on the pressurizing piston and two brakes acting on the pressurizing piston.
When the hydraulic pressure is released to the reservoir tank, the opening / closing valve is opened and delayed to delay the switching valve to the hydraulic pressure releasing mode, and the opening / closing valve is opened and then the delaying means is used. Failure determination means for performing failure determination of the on-off valve according to the magnitude of the brake fluid pressure detected by the pressure detection means until the switching valve is switched to the hydraulic pressure release mode. It can be configured to further include.

When the failure determination means determines that the on-off valve has a failure, an alarm device such as a buzzer or a lamp can be operated. In this case, as long as the switching valve operates normally, The switching control of the switching valve, that is, the control for obtaining the automatic brake can be continued as it is.

[0013]

As described above, according to the present invention, a bypass passage is provided for releasing the brake fluid pressure acting on the pressurizing piston to the reservoir tank by bypassing the switching valve.
Since the on-off valve is provided in this bypass passage, even if the switching valve remains stuck in the fluid pressure supply mode, the brake fluid pressure acting on the pressurizing piston is forced by opening the on-off valve. In addition, the automatic brake can be released by releasing it to the reservoir tank, and the vehicle can be run without any support.

With the structure as described in claim 2, the changeover valve is in the hydraulic pressure supply mode by checking whether or not the pressure detected by the pressure detecting means rises during the delay by the delay means. It is possible to easily and surely know whether or not a failure has occurred. Further, as described in claim 3, when it is determined that the switching valve is stuck in the hydraulic pressure supply mode, the on-off valve is forcibly held in the open state so that the automatic brake is maintained. Is prevented.

According to the structure described in claim 4, by checking whether or not the pressure detected by the pressure detecting means is reduced during the delay by the delay means, the on-off valve is fixed in the closed state. You can easily and surely know the failure. Then, by operating the alarm device as described in claim 5, the driver can easily know the failure. Preferred aspects of the invention and advantages thereof will become apparent from the description of the examples below.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, reference numeral 1 denotes a master cylinder as a first hydraulic pressure generating means, which is a brake pedal 2 operated by a driver.
Is stepped up by the booster 3 and transmitted to the master cylinder 1, and a brake hydraulic pressure corresponding to the stepping force is generated in the master cylinder 1.

The master cylinder 1 has two discharge ports 1a,
It is a tandem type having 1b. The pipe 4 extending from the discharge port 1a is branched into two in the middle, one branch pipe 4a is connected to the brake device 5FL for the left front wheel, and the other branch pipe 4b is connected to the brake device 5FR for the right front wheel. It is connected.

A pressurizing device 7 which will be described later is connected in the middle of the pipe 6 extending from the discharge port 1b, and a portion upstream of the pressurizing device 7 (on the side of the master cylinder 1) is indicated by reference numeral 6A.
The portion downstream of the pressurizing device 7 is indicated by reference numeral 6B. The downstream side pipe 6B is branched into two in the middle, one branch pipe 6a is connected to the left rear wheel braking device 5RL, and the other branch pipe 6b is connected to the right rear wheel braking device 5RR. It is connected. In the embodiment, the front wheels are driven wheels and the rear wheels are drive wheels.

The pressure device 7 is constructed as follows.
First, the pressure piston 12 is slidably inserted into the casing 11 so that the inside of the casing 11 is compressed by the pressure piston 12.
Is defined by two liquid chambers 13 and 14. The liquid chamber 14 is separated from the liquid chamber 15 by a partition wall 7a formed in the casing, and a communication port 16 is formed in the partition wall 7a to connect the both liquid chambers 14 and 15.

The liquid chambers 13 and 15 are located in the axial direction of the pressurizing piston 12 with the liquid chamber 14 interposed therebetween. A movable valve body 17 is held on the pressurizing piston 12 so as to be slidable in the axial direction of the pressurizing piston 12. The movable valve body 17 has a valve body portion 17a which faces the communication port 16, and the spring 18 causes the valve body portion 17a to approach the communication port 16, that is, in the direction of approaching the partition wall 7a which functions as a valve seat. Being energized.

In the pressurizing piston 12, a spring 19 (set to have a larger urging force than the spring 18) arranged in the liquid chamber 14 causes the valve body portion 17a to the left in FIG. It is urged away. As shown in FIG. 1, when the pressurizing piston 12 is at the left stroke end thereof, that is, the stroke end in the direction away from the communication port 16, the valve body portion 17a keeps the communication port 16 open. .. When the pressurizing piston 12 moves rightward from the state of FIG. 1, the communication port 16 is closed by the valve body portion 17a. The pressurizing piston 12 can further move rightward from the state where the valve body portion 17a closes the communication port 16, and at this time, the movable valve body 17 is slidably displaced relative to the pressurizing piston 12. ..

The casing 1 is provided with a port 20 which is always open to the liquid chamber 13, a port 21 which is always open to the liquid chamber 14, and a port 22 which is always open to the liquid chamber 15. .. The upstream pipe 6a extending from the master cylinder 1 is connected to the port 22, and the downstream pipe 6B connected to the rear wheel brake devices 5RL and 5RR is connected to the port 21. .. As a result, the valve body 17a is connected to the communication port 1
In the state where 6 is opened, the brake fluid pressure generated in the master cylinder 1 is changed to the upstream pipe 6A, the fluid chamber 15, the communication port 16,
The brake device 5 for the rear wheel is passed through the liquid chamber 14 and the downstream pipe 6B.
It will be supplied to RL and 5RR.

The port 20 opening to the liquid chamber 13 is provided with the pipe 3
It is connected to the switching valve 32 via 1. Switching valve 32
Is a 3-port 2-position electromagnetic type, and the piping 3
3 and 34 are also connected. The pipe 33 is connected to the reservoir tank 35 to form a relief passage. The pipe 34 is connected to a pump 37 driven by a motor 36 and constitutes a brake fluid pressure supply passage for automatic braking.

An accumulator 41 and a pressure sensor 42 are connected to the pipe 34. The pipes 31 and 33 are connected by a pipe 43 that bypasses the switching valve 32, and an electromagnetic on-off valve 44 is connected to the pipe 43. A pressure sensor 45 is also connected to the pipe 31. Further, the pipes 34 and 33 are connected by a relief pipe 46 that bypasses the switching valve 32, and a pressure-responsive relief valve that is opened when the pressure in the pipe 34 becomes a predetermined pressure or more. The valve 47 is connected.

Among the pipes 6 connected to the master cylinder 1, an upstream pipe 6A and a downstream pipe 6B, which are separated by a pressurizing device 7, are connected by a pipe 51 bypassing the pressurizing device 7. A fail valve 52, which is an electromagnetic on-off valve that is normally closed, is connected to the pipe 51.

FIG. 2 shows a control system. In the figure, U1 and U2 are control units each configured by using a microcomputer, and as known, CP
U, ROM, RAM, CLOCK, I / O interface
It is equipped with In addition to the pressure signals detected by the pressure sensors 42 and 45, the control unit U1 is supplied with a signal from the control unit U2 indicating the presence or absence of a request for automatic braking. Further, from the control unit U1, each of the valves 3
2, 44, 52, and an alarm device W such as a lamp or a buzzer.

The control unit U2 is used, for example, for traction control, and when the rotation speed of the rear wheels as driving wheels becomes excessive compared to the vehicle speed, the control unit U1 automatically controls the control unit U1 to apply a braking force to the driving wheels. A break request (pressurization request) signal is output. That is, the control unit U2
Except for the control of each valve 32, 44, 52 for automatic braking by the control unit U1 described later, control is performed until it is determined whether or not automatic braking is required. Since the traction control is well known, its detailed description is omitted. In addition, the control unit U2 is for appropriate control such as a signal for requesting automatic braking when the vehicle approaches the preceding vehicle too much. Can be

In the above configuration, when automatic braking is not performed, the following is performed. That is, the switching valve 32 connects the pipes 31 and 33 to each other to release the liquid chamber 13 to the reservoir tank 35, which is a hydraulic pressure release mode. Further, the opening / closing valve 44 is opened, and the pipe 31, that is, the liquid chamber 13 is opened to the reservoir tank 35 through the bypass pipe 43. Further, the fail valve 52 is kept closed.

Therefore, the brake fluid pressure from the pump 37 does not act on the liquid chamber 13, and the pressurizing piston 12 is positioned at the left stroke end by the spring 19 as shown in FIG. The communication port 16 is opened. As a result, as described above, the brake fluid pressure generated in the master cylinder 1 by depressing the brake pedal 2 is
Not only the brake devices 5FL and 5FR for the front wheels but also the brake devices 5RL and 5RR for the rear wheels can be supplied with them to obtain a normal brake action. When the brake pedal 2 is released, the brake hydraulic pressures of the brake devices 5FL to 5RR are released to the master cylinder 1 to release the brake.

Next, an example of control by the control unit U1 when performing automatic braking will be described with reference to the flow charts shown in FIGS. In the following description, S is a step. First, after the data is input in S1 of FIG. 3, whether or not the automatic brake is requested (pressurization request) is made by observing the signal from the control unit U2 in S2. Is determined. When the determination in S2 is YES, it is determined in S3 whether or not the pressurization is currently being performed (during automatic braking).

When the determination in S3 is NO, the control for obtaining the automatic braking force using the pressure piston 12 of the pressure device 7 is started from the state shown in FIG. in this case,
In S4, the on-off valve 44 is closed first. After this,
After waiting a predetermined time in S5, in S6, the pressure of the pipe 31 detected by the sensor 45 (the liquid chamber 13
After the pressure P1 is read, it is determined in S7 whether or not the pressure P1 has risen. The above S
The predetermined time in 5 is a short time until the influence of the pressure change on the pipe 31 due to the closing of the opening / closing valve 44 appears.

At the time of S7, the switching valve 32 is still in the state of shutting off the pipes 31 and 34 (the pipe 31
When the switching valve 32 is normal, the pressure P1 does not tend to increase. When the determination in S7 is NO, in S8, the switching valve 32 communicates with the hydraulic pressure, that is, the pipe 31 communicates with the pipe 34 and the pipe 33 (reservoir
It is switched to a hydraulic pressure supply mode in which communication with the tank tank 35) is cut off.

Thereafter, it is determined whether or not the pressure of the pipe 31 detected by the pressure sensor 45 and the pressure P2 of the pipe 34 detected by the pressure sensor 42 are equal (substantially equal). If the result of the determination in S9 is YES, it is determined that there is no abnormality and the process directly returns to S1. After once passing through S9, the determination in S3 becomes YES, and the process proceeds to S9.

By switching the switching valve 32 to the hydraulic pressure supply mode in S8, the brake hydraulic pressure from the pump 37 is supplied to the liquid chamber 13. As a result, the pressurizing piston 12 moves rightward in FIG. 1, and the communication port 16 is first closed by the valve body portion 17a of the movable valve body 17. Further pressurizing piston 12
1, the liquid chamber 14 is pressurized by the rightward movement, and the brake fluid pressure of the liquid chamber 14 generated by this pressurization is supplied to the brake devices 5RL, 5RR for the rear wheels, and the rear wheels concerned. Braking force will be applied to.

If the result of the determination in S7 is YES, it is considered that the switching valve 32 is stuck in a hydraulic pressure supply mode in which the pipes 31 and 34 are in communication with each other and is in a failure state. In addition, N is determined in S9.
When O, the switching valve 32 connects the pipe 31 to the reservoir tank 3
It is considered that it is a time of failure that the pressure is released to No. In this case, both of the on-off valve 44 in S10
Is forcibly opened, and thereafter the alarm device W is activated. Thus, when the switching valve 32 fails, the on-off valve 44
By forcibly opening and releasing the pressure in the liquid chamber 13, it is possible to reliably prevent the situation in which the automatic brake remains hard. Then, at the time of this failure, the control is ended here, and the automatic brake control by the switching control of the switching valve 32 is not performed (inhibited).

When the determination in S2 is NO, S in FIG.
Move to 21. In this S21, it is judged whether or not the pressurization is currently being performed (during automatic braking). If the determination in S21 is NO, there is no pressurization request, and since no pressurization is currently being made, the printer waits for the next pressurization request and then returns.
Will be

If the determination in S21 is YES, the liquid chamber 13
It is time to release the pressure of. At this time, first, S2
After opening the on-off valve 44 in 2, wait for a predetermined time (the same meaning as the predetermined time in S5) to elapse in S23,
In S24, the pressure of the pipe 31 detected by the pressure sensor 45 is read. Next, in S25, the pressure P1
Is determined.

If the determination in S25 is YES, the on-off valve 4
4 is operating normally and is in the open state. At this time, the switching valve 32 is switched to the hydraulic pressure releasing mode in S26 to release the brake hydraulic pressure of the liquid chamber 13 to the reservoir tank 35. .. After that, in S27, it is determined whether or not the pressure P2 is considerably higher than P1. When the determination in S27 is YES, the switching valve 32 is returned as it is, assuming that the switching valve 32 is actually switched to the hydraulic pressure releasing mode.

If the determination in S27 is NO, it is considered that the switching valve 32 is stuck in the hydraulic pressure supply mode and is in failure. In this case, the process proceeds to S10 described above, and the control mode at the time of failure is set.

If NO in the determination in S25, it is considered that the on-off valve 44 is stuck in the closed state and is in a failure. In this case, in S28, after activating the alarm device W, S
At 29, the fail valve 52 is opened and the process proceeds to S26 (the automatic brake control is not prohibited). As described above, by opening the fail valve 52, even if the communication port 1
Even in the case where the brake 6 remains closed, if the brake pedal 2 is released, the brake hydraulic pressure of the brake devices 5RL and 5RR is released to the master cylinder 1 through the pipe 51, and the brake fluid is released. Cancellation will be obtained. Of course, blur
When the pedal 2 is depressed, the master cylinder 1
The brake fluid pressure generated in step (3) is supplied to the brake devices (5RL, 5RR) via the pipe (51), and the brake operation can be obtained by the driver's intention.

Although the embodiment has been described above, the liquid chamber 13
When it is necessary to delicately control the hydraulic pressure supplied to the brake, it can be performed by, for example, duty-controlling the switching valve 32, or by controlling a variable throttle connected to a separate pipe 34. ..

[Brief description of drawings]

FIG. 1 is a brake fluid system diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a control system.

3 is a flow chart showing an example of control of the brake hydraulic pressure system shown in FIG.

4 is a flow chart showing an example of control of the brake hydraulic pressure system shown in FIG.

[Explanation of symbols]

 1: Master Cylinder (First Liquid Pressure Generating Means) 2: Brake Pedal 6: Brake Pipe (First Liquid Pressure System Path) 5RL, 5RR: Brake Device 7: Pressurizing Device 12: Pressurizing Piston 13 : Liquid chamber 14: Liquid chamber 15: Liquid chamber 16: Communication port 17: Movable valve body 31: Piping 32: Switching valve 33: Piping 34: Piping 35: Reservoir tank 37: Pump (second liquid pressure generating means) 43 : Bypass piping 44: Open / close valve 45: Pressure sensor

Claims (5)

[Claims] 1. A brake operated by a driver for a brake operation.
First hydraulic pressure generating means for generating a hydraulic pressure; a first hydraulic pressure path for supplying the brake hydraulic pressure generated by the first hydraulic pressure generating means to a braking device for braking of a vehicle; Second hydraulic pressure generating means for generating a brake hydraulic pressure irrespective of a brake operation by a driver, and the above-mentioned when the brake hydraulic pressure generated by the second hydraulic pressure generating means is received. A pressurizing piston that pressurizes the brake fluid in the first hydraulic pressure path to operate the brake device, and a brake hydraulic pressure generated by the second hydraulic pressure generating means to the pressurizing piston. A switching valve for switching between a hydraulic pressure supply mode to be supplied and a hydraulic pressure release mode for releasing the brake hydraulic pressure applied to the pressurizing piston to the reservoir tank, and the brake acting on the pressurizing piston. A bypass passage for releasing the liquid pressure to the reservoir tank by bypassing the switching valve. Key device - blur vehicle, characterized in that it comprises a opening and closing valve connected to the bypass passage. 2. The pressure detecting means for detecting a brake fluid pressure acting on the pressurizing piston, and the brake from the second brake fluid pressure generating means on the pressurizing piston according to claim 1. A delay means for switching the switching valve to the hydraulic pressure supply mode by delaying after closing the opening / closing valve when applying the hydraulic pressure; and the switching valve by the delaying means after the opening / closing valve is closed. Failure determination means for determining a failure of the switching valve according to the change state of the brake hydraulic pressure detected by the pressure detection means until the switching to the hydraulic pressure supply mode is further provided. thing. 3. The device according to claim 2, further comprising failure response means for forcibly holding the open / close valve in an open state when the failure determination means determines that the switching valve has a failure. 4. The pressure detecting means for detecting the brake fluid pressure acting on the pressurizing piston, and the two brake fluid pressure acting on the pressurizing piston as claimed in claim 1. -When releasing to the tank, delay means for delaying after opening the on-off valve to switch the switching valve to the fluid pressure releasing mode; and after the opening / closing valve is opened, the switching valve causes the switching valve to switch to the liquid state. A failure determination means for determining a failure of the on-off valve according to the change state of the brake hydraulic pressure detected by the pressure detection means until the pressure is released. 5. The alarm device according to claim 4, further comprising an alarm unit that is activated when the failure determination unit determines that the on-off valve has a failure.