JPH1178848A - Device for controlling brake fluid pressure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten wheel cylinder pressure in nearly the same way as a boosting function is activated when a brake operation member is operated, in the time that the boosting function is not properly activated as running. SOLUTION: This device is provided with the second boosting device A which is prepared with a pump 9 for fail which can discharge the fluid from a master cylinder to the wheel cylinder side, a shut valve 10 of an open type arranged in a pipeline provided parallel to the pipeline, a balance valve 11 arranged within a pipeline provided parallel to the pipeline of the shut valve 10, in the piping communicating the master cylinder with the wheel cylinders. Thus, in the time of trouble, the shut valve 10 is closed and the brake can be applied, then the balance valve 11 heighten the pressure of the wheel cylinders 7, 8 for the input pressure from the master cylinder 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake fluid pressure control device having a boosting function such as a vacuum brake booster or a hydraulic brake booster. Even if the force function does not work properly,
The present invention relates to a brake fluid pressure control device capable of performing a brake operation when a brake operation member is operated, in substantially the same manner as when a boost function is operating.

[0002]

2. Description of the Related Art In general, an unfamiliar driver or a driver who has become accustomed and has fallen into a panic state cannot step on the brakes strongly and cannot maintain the pedaling force for a long time. For this reason, the development of brake fluid pressure control devices that maximize the performance of brakes, including anti-lock control systems, has recently been promoted, and as one of such development directions, various developments related to improving the performance of brake boosters have been carried out. Is underway.

[0003]

SUMMARY OF THE INVENTION For example, Japanese Patent Application Laid-Open No. H8-8
The brake booster (hydraulic booster) described in No. 7430 has a movable valve body slidably disposed in a piston that slides in a cylinder hole in the hydraulic booster, and the movable valve is provided with a movable valve body. By supporting the left and right ends of the body with seal rings,
Vibration of the movable valve body due to a rapid flow of hydraulic pressure during operation of the device is suppressed, and generation of abnormal noise is prevented.

In the above-mentioned hydraulic booster, for example, an engine trouble occurs during running and the engine is stopped, so that a negative pressure is no longer generated in the vacuum brake booster, or the booster is not used. When the brake operation member is operated in a state where the accumulator has failed, the boosting function does not operate normally. In order to prepare for such a situation, the conventional brake device transmits the hydraulic pressure generated in the master cylinder to the wheel cylinder as it is, even if the above-mentioned situation occurs, so that the brake can be operated safely. It has a structure. However, in such a state, there is a problem that the pedal effort of the brake pedal fluctuates greatly from the normal state.

Accordingly, the present invention newly provides a fail pump system which operates when a brake operating member is operated in a state where an engine trouble or a failure has occurred in an accumulator or the like in a conventional brake device. It is another object of the present invention to provide a brake fluid pressure control device capable of securing a braking force as normal, and to solve the above-mentioned problems.

According to the present invention, a pump which operates by detecting the occurrence of the above-described abnormality in a brake hydraulic circuit including a conventional anti-lock control modulator, and opens and closes by a command from an electronic control unit. An extremely safe brake fluid pressure control device can be obtained only by retrofitting a shut valve and a balance valve for adjusting the fluid pressure in the wheel cylinder when the pump operates. Further, since there is no significant change in the brake circuit or the like, it is advantageous in terms of cost.

[0007]

For this reason, the technical solution adopted by the present invention is that when the brake operating member is operated when the function of the brake booster is abnormal in the pipe connecting the master cylinder and the wheel cylinder. A brake fluid pressure control device, comprising: a second booster that operates, wherein a brake can be operated by the second booster when an abnormality occurs, wherein the second booster includes a master cylinder and a wheel cylinder. And a fail-opening pump 9 which is arranged in a pipeline between which can pump up the brake fluid from the master cylinder and discharge it to the wheel cylinder side, and a normally-open type which is arranged in a pipeline provided in parallel with the pipeline of the failing pump 9. A shut valve 10 and a balance valve 11 disposed in a pipe provided in parallel with the pipe of the shut valve 10.
When the second booster is operated, the shut-off valve 10 is closed to apply the discharge pressure of the fail pump 9 to the brake cylinder so that the brake can be applied. A brake fluid pressure control device characterized in that the pressure of the wheel cylinders 7 and 8 is controlled to increase with respect to the input pressure from

A second booster, which is activated when a brake operating member is operated when the function of the brake booster is abnormal, is disposed in a pipe connecting the master cylinder and the wheel cylinder, and the second booster is operated when the brake booster fails. A brake fluid pressure control device capable of operating a brake by a device, wherein the second booster is disposed in a pipeline between a master cylinder and a wheel cylinder, and pumps brake fluid from the master cylinder to a wheel cylinder side. Pump 9 that can discharge to
, A normally-open shut-off valve 10 disposed in a conduit provided in parallel with the conduit, a balance valve 11 disposed in a conduit provided in parallel with the conduit of the shut-off valve 10, and a normally-closed cut valve. 25 and shut valve 1
0, the normally closed cut valve 25 is opened, and the discharge pressure of the fail pump 9 is applied to the brake cylinder to apply a brake. The balance valve 11 is operated by the wheel cylinders 7 and 8 with respect to the input pressure from the master cylinder 3.
A brake fluid pressure control device characterized in that the pressure is controlled to increase with respect to the master cylinder pressure, and when the vehicle stops, the state is detected and the shut valve 10 is closed to maintain the wheel cylinder pressure. It is.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a brake fluid pressure control device according to a first embodiment. In FIG. 1, 1 is a brake pedal as a brake operating member, 2 is a brake booster (first booster), 3 is a tandem master cylinder, and two pipe routes 4 for front and rear wheels from the tandem master cylinder. 5 are provided. The end of each of the piping paths 4 and 5 is branched 6 to form a front wheel cylinder (W
/ C) 7, connected to the rear wheel cylinder 8
Tandem master cylinder 3 and wheel cylinders 7, 8
A second booster A, as shown, comprising a fail pump 9, a shut valve 10, a balance valve 11, and the like, which is a feature of the present invention, is disposed in the middle of the pipe to the branch point 6 of FIG.

A conventionally known antilock modulator (ABS device) B comprising a hold valve, a decay valve, an antilock control reservoir, a hydraulic pump, and a motor is arranged in a pipe path branched for each wheel. . The first booster (brake booster) 2, the master cylinder 3, and the wheel cylinder 4 also have the same configuration as conventionally known ones. In this example, the ABS device B is provided for each wheel. Various forms such as independent front wheels and common rear wheels can be adopted. The second booster A provided in each of the two pipe paths 4 and 5 has the same configuration except for the common motor M that drives the fail pump, and has an electronic control device (the electronic control device that controls the second booster A). ECU)
The electronic control unit (ECU) includes a sensor that detects a failure of the accumulator in addition to signals from various sensors (such as a speed sensor) used in the conventional antilock control. A signal from an (accumulator pressure is detected), an L terminal for detecting an engine stop (the generator does not work due to the engine stop, the voltage is reduced), and a signal from a brake switch are input.

Hereinafter, a description will be given of the second booster A disposed in one piping path (the path on the right side in the figure) 5 with reference to FIG.
More specifically, the hydraulic pressure operated by a common motor M driven by a command from an electronic control unit (ECU) is provided in the pipe between the pipe branch point 6 to the left and right wheels and the master cylinder 3. A pump 9 is provided, and a shutoff valve 10 for switching a position in response to a command from an electronic control unit (ECU) is provided in a pipe provided in parallel with the pipe of the hydraulic pump 9. A balance valve 11 is disposed in a pipe provided in parallel with the pipe of the shut valve 10. The discharge port of the hydraulic pump 9 is connected to a second hydraulic chamber 15 (described later) of the balance valve via a pipe 31.

The shut valve 10 is configured as a normally-open two-position switching valve. The shut valve 10 is provided with a fail-safe check valve 10 a in parallel, and the shut valve 10 drives the hydraulic pump 9. At the same time, it is configured to switch to the closed state in response to a command from an electronic control unit (ECU). Also the balance valve 11
Is provided with a stepped piston 13 slidably in a two-stage cylinder 12 having a different inner diameter, and a large-diameter portion 12a of the cylinder 12 has a large-diameter portion of the stepped piston 13 (pressure receiving area A).
1) is divided into a first hydraulic chamber 14 and a second hydraulic chamber 15. The first hydraulic chamber 14 is connected to the master cylinder 3, and the second hydraulic chamber 15 is connected to a discharge port of the hydraulic pump 9 via a pipe 31. In the small diameter 12b, the small diameter portion of the stepped piston 13 (pressure receiving area A
The atmosphere chamber 16 is partitioned by 2). Atmospheric chamber 16
A spring 17 for urging the stepped piston 13 upward in the drawing is provided therein.

A valve storage chamber 13a is formed in the center of the stepped piston 13. The valve storage chamber 13a is firstly opened by a flow path 13b formed in the stepped piston 13.
The flow passage 13b communicates with the hydraulic pressure chamber 14 and the second hydraulic pressure chamber 15, and can be maintained in an open state by contacting an engaging rod 18 provided on the cylinder side in the valve storage chamber 13a. A valve body 19 is arranged. The valve body 19 is urged by a valve spring 20 toward a valve seat 13c formed in the flow path 13b. When the valve body 19 is not operated, the valve body 19 abuts on the engaging rod 18 to keep the flow path 13b open.
When the stepped piston 13 moves downward from the state of FIG. 1 against the urging force of the spring 17, the valve body 19
The flow path 13b can be closed by abutting on c. In addition, 21 and 22 are sealing members.

The operation of the brake fluid pressure control device having the above configuration will be described. Normal operation In FIG. 1, when the brake pedal 1 is operated, a hydraulic pressure is generated in the master cylinder 3 by the force assisted by the brake booster (first booster) 2, and the hydraulic pressure is generated in the pipes 4 and 5. Are transmitted to the respective wheel cylinders 7 and 8 via the hold valves in the respective ABS devices B through the open shut valves 10 of the second booster A disposed in the above, and the brakes are operated. When the brake pedal 1 is released, the hydraulic pressure in the wheel cylinders 7 and 8 returns to the master cylinder 3 through the reverse route, and the brake is released. If the wheels tend to lock while the brakes are operating, the ABS device B performs the same anti-lock control as before by the command from the electronic control unit (ECU), and holds, reduces, and re-presses the brake fluid pressure. I do. This anti-lock control mode can adopt the conventional one as it is,
Since the control mode is the same, detailed description is omitted.

In the event of an abnormality If an engine trouble or a fault occurs in the accumulator or the like and a malfunction occurs in the function of the brake booster, the state is input to the electronic control unit (ECU) as an L terminal signal or a brake booster fault signal. When the ON signal of the brake switch is input, the motor M of the failure pump 9 is driven, and at the same time, the shut valve 10 is closed. When the failure pump 9 is driven, the hydraulic pressure from the master cylinder 3 is pumped up and increased, and the ABS device B
To the wheel cylinders 7 and 8 to operate the brake. At this time, the pressure of the wheel cylinders 7 and 8 with respect to the input pressure from the master cylinder 3 is controlled to increase according to a predetermined relationship as follows.

That is, when the hydraulic pressure generated in the master cylinder 3 reaches a predetermined value (a hydraulic pressure P described later), the hydraulic pressure acting on the first hydraulic chamber 14 in the balance valve 3 causes the stepped piston 13 to move the spring 17. 1 moves downward in FIG. 1 against the urging force of FIG.
Close.

The relationship between the hydraulic pressure when the valve body 19 contacts the valve seat 13c and the force of the spring 17 will now be described.
The hydraulic pressure in the hydraulic chamber 14 is P1, the hydraulic pressure in the second hydraulic chamber 15 is P2, the force of the spring is F, the pressure receiving area of the large-diameter portion of the stepped piston 13 is A1, and the small-diameter portion of the stepped piston is A1. Assuming that the pressure receiving area is A2, P1 · A1 = P2 (A1−A2) + F (1) Here, at the beginning of operation, the flow path 13b is open and P1 =
Since the pressure P is P2, when the hydraulic pressure P becomes P = A2 / F, the stepped piston 13 moves against the urging force of the spring 17, and the valve body 19 comes into contact with the valve seat 13c and the flow path 1
3b will be closed. Thereafter, as shown in the following equation (2) obtained by the equation (1), the hydraulic pressure P2 is changed to the hydraulic pressure P1.
Is increased in a predetermined relationship. As a result, the hydraulic pressure of the wheel cylinders 7 and 8 is increased with respect to the hydraulic pressure of the master cylinder 3. P2 = [P1 · A1 / (A1-A2)]-F / (A1-A2) (2)

In this way, even when the function of the brake booster is abnormal, the balance valve 11 increases the pressure of the wheel cylinders 7 and 8 in a predetermined relationship with respect to the input pressure from the master cylinder 3. It is possible to obtain a braking force corresponding to the hydraulic pressure of the master cylinder 3 substantially at the same time. When the brake pedal 1 is released, the failure pump 9 stops, and the shut valve 10
Is opened, the brake fluid in the wheel cylinder flows back to the master cylinder 3 via the opened shut valve 10, and the brake is released.

If the wheels tend to lock during the normal or abnormal braking operation, the ABS device is operated by a command from the electronic control unit to control the brake fluid pressure to control the wheel hydraulic pressure, similarly to the conventional device. Avoid locking propensity.

Next, a description will be given of a second embodiment. FIG. 2 is a configuration diagram of the second embodiment. The second embodiment is the first
The embodiment is characterized in that a slope start assist function is added, and as shown in FIG.
A normally-closed normally-cut valve 25 is provided in a pipe 31 connecting the second hydraulic chamber 15 and the discharge port of the hydraulic pump 9. The electronic control unit receives a new gear engagement signal and clutch connection signal for slope start control. In the second embodiment, as in the first embodiment, when the brake booster fails or the engine is stopped and the brake switch is turned on, the fail pump 9 operates as shown in FIG. Then, the shut valve 10 is closed, and the normally closed cut valve 25 is further opened. As a result, by the same operation as in the first embodiment, the wheel cylinder pressure can be increased corresponding to the master cylinder pressure by the pressure increasing action determined by the area ratio of the balance valve 11.

When a predetermined time (several seconds) elapses after the vehicle stops and the brake pedal is continuously depressed, the state is detected by a sensor, and when the shut valve 10 is closed as shown in FIG. 4 by a command from the electronic control unit. (The cut valve 25 is a normally-closed type and is closed at this time), and seals the brake fluid pressure in the wheel cylinder. After this state, the braking force is maintained even when the brake pedal is released. When the vehicle is started in this state (for example, when a gear input signal and a clutch connection signal are input to the electronic control unit), the shut-off valve 10 is opened by a command from the electronic control unit, and the brake fluid pressure becomes master. Opened to cylinder. Thus, an inexperienced driver can easily start on a slope without performing complicated clutch and brake operations. The vehicle start operation state can be detected from various states of the vehicle, and the valve can be controlled by the electronic control device by appropriately combining the states.

As described above, according to the present invention, even if the brake booster fails or the engine is stopped, the second booster can provide a pressure increasing function substantially the same as in a normal state, so that the safety is high. Become. Also, the normally closed cut valve 25
By simply adding, even an inexperienced driver can easily start on a slope. Further, in the second embodiment, the same function can be achieved by disposing the above-described normally-closed cut valve 25 at a dotted line position indicated by reference numeral 26 in FIG. Furthermore, in each of the above embodiments, the second booster is disposed in each of the two brake piping systems using the tandem master cylinder, but the second booster is disposed in only one of the two systems. Is also good.

[0023]

As described in detail above, according to the present invention,
When the brake booster fails or the engine stops, the fail pump in the second booster is activated, and the hydraulic pressure from this pump and the balance valve cooperate to increase the pressure corresponding to the master cylinder. The obtained wheel cylinder pressure can be obtained, and a highly safe brake fluid pressure control device can be obtained. In addition, since it has a configuration that can be retrofitted to a conventional brake fluid pressure control device, it can be applied to various types of vehicles, and the entire system can be configured at low cost. By adding a cut valve, Slope start assist control can be performed, and excellent effects such as easy driving can be achieved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a brake fluid pressure control device according to a first embodiment.

FIG. 2 is a configuration diagram of a brake fluid pressure control device (normal state) according to a second embodiment.

FIG. 3 is a main part configuration diagram illustrating a state in which a shut valve is closed and a normally-closed cut valve is opened (failure state) in the second embodiment.

FIG. 4 is a main part configuration diagram showing a state where both a shut valve and a normally closed type cut valve are closed (a slope start control state) in the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brake pedal 2 Brake booster 3 Tandem master cylinder 4, 5 Piping 6 Branch point 7, 8 Wheel cylinder 9 Fail pump 10 Shut valve 11 Balance valve 25 Normally closed cut valve A Second booster B ABS device

Claims (3)

[Claims] A second booster which operates when a brake operating member is operated when a function of a brake booster is abnormal, is disposed in a pipe connecting the master cylinder and the wheel cylinder; A brake fluid pressure control device capable of operating a brake by a force device, wherein the second booster device is disposed in a pipeline between a master cylinder and a wheel cylinder, and pumps brake fluid from the master cylinder to a wheel cylinder. Pump 9 that can be discharged to the side, and this fail pump 9
A normally open shut valve 10 disposed in a conduit provided in parallel with the conduit of the above, and a balance valve 11 disposed in a conduit provided in parallel with the conduit of the shut valve 10. When the booster is operated, the shut-off valve 10 is closed to apply the discharge pressure of the fail pump 9 to the brake cylinder so that the brake can be applied, and the balance valve 11 responds to the input pressure from the master cylinder 3. A brake fluid pressure control device for controlling the pressure of the wheel cylinders 7 and 8 to increase. A second booster which operates when a brake operating member is operated when a function of the brake booster is abnormal, is disposed in a pipe connecting the master cylinder and the wheel cylinder, A brake fluid pressure control device capable of operating a brake by a booster, wherein the second booster is disposed in a conduit between a master cylinder and a wheel cylinder, and a wheel for pumping brake fluid from the master cylinder. A fail pump 9 capable of discharging to the cylinder side;
, A normally-open shut-off valve 10 disposed in a conduit provided in parallel with the conduit, a balance valve 11 disposed in a conduit provided in parallel with the conduit of the shut-off valve 10, and a normally-closed cut valve. 25 and shut valve 1
0, the normally closed cut valve 25 is opened, and the discharge pressure of the fail pump 9 is applied to the brake cylinder to apply a brake. The balance valve 11 is operated by the wheel cylinders 7 and 8 with respect to the input pressure from the master cylinder 3.
A brake fluid pressure control device characterized in that the pressure is controlled to increase with respect to the master cylinder pressure, and when the vehicle stops, the state is detected and the shut valve 10 is closed to maintain the wheel cylinder pressure. . 3. The brake fluid pressure control device according to claim 1, wherein an ABS device is disposed between the second booster and the wheel cylinder.