JP2000062605A - Method and device for detecting brake defect for vehicle anti-skid hydraulic pressure control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge that a system not anti-skid controlled as a defect by detecting that only the wheel cylinder of the wheel of one system is anti-skid controlled, and detecting that the wheel speed of the wheel of the system not anti-skid controlled is within a prescribed range. SOLUTION: When a control is started (A), depression of a brake pedal is detected (B), and it is judged whether only one system is under anti-skid (ABS) control or not (C). It is whether the body speed is larger than a set minimum value or not (B), and it is also judged whether it is under the control of 2 cycles or more (E). Further, it is judged whether the wheel speed not under control is within a prescribed range or not (F). Namely, since a slight difference in wheel speed is caused when the brake piping of the front wheel system is defective, the brake defect of the front wheel system is judged. According to this, the brake defect of a control device having two brake systems can be quickly and surely detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake failure detection method and device for an antiskid hydraulic pressure control device for a vehicle.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional anti-skid control device. In FIG. 4, one side of the master cylinder 1 has a right front wheel FR and a left rear wheel RL via a conduit 31a.
The wheel cylinder of the left front wheel FL and the wheel cylinder of the right rear wheel RR are connected to the other brake system via the conduit 31b. That is, X piping is adopted. Also, 2-port, 2-position electromagnetic switching valves 7A, 7B, 7C, 7D, 8A, 8B, 8
C, 8D, a right front wheel FR and a left rear wheel RL are provided with a reservoir 30A and a left front wheel FL and a right rear wheel RR are provided with a reservoir 30B. And these are the pipe lines 3 communicating with the first and second hydraulic pressure generating chambers of the master cylinder 1.
Check valves 32a, 32 that are directly connected to 1a, 31b and have forward direction to the master cylinder 1 side
b is provided. The first two-port, two-position solenoid operated directional control valves 7A, 7B, 7C, 7D are provided in parallel with a check valve g having a forward direction toward the master cylinder 1.

When increasing the hydraulic pressure of the wheel cylinder, the first two-port, two-position electromagnetic switching valves 7A, 7B,
7C and 7D are in the communicating position, and therefore, through this, the hydraulic fluid is supplied to the wheel cylinder and the brake is applied.

When a control unit (not shown) should release the brake (it is assumed that all the wheels are changed in the same skid condition for the sake of clarity), the second two ports and the two positions are set. The solenoid portions of the electromagnetic switching valves 8A to 8D are excited to be in communication with each other, while the first two-port, two-position electromagnetic switching valves 7A to 7 are used.
The solenoid portion of D is also excited and turned off. As a result, the pressure fluid in the wheel cylinder is in the second 2 ports,
The reservoir 30A through the two-position electromagnetic switching valves 8A to 8D,
It is discharged to 30B. This releases the brake. As in the conventional example, the hydraulic pump is not provided in the present embodiment as well, so that the brake fluid discharged to the reservoirs 30A30B remains stored. That is, the amount by which the brake is released is determined by the capacity of these reservoirs 30A and 30B.

When the control unit (not shown) first judges that the brake should be held, the solenoid portion of the first two-port, two-position electromagnetic switching valves 7A to 7D is excited to activate the second two-port, two-position electromagnetic switch. The solenoids of the switching valves 8A to 8D are kept in a non-excited state, and the hydraulic fluid in the wheel cylinders is kept at a constant hydraulic pressure. Therefore, the wheel brake pressure is kept constant.

When the braking force is increased, the solenoid portion of the first two-port, two-position electromagnetic switching valves 7A to 7D is intermittently excited to increase the hydraulic pressure of the wheel cylinder stepwise. If the control unit determines that the braking force should be increased and the control unit should release the brake again, the first two
The ports and the two-position electromagnetic switching valves 7A to 7D are in the shut-off state, and the solenoid portions of the second two-port and two-position electromagnetic switching valves 8A to 8D are excited to be in the communication state, and the reservoir 30
The brakes on the wheels are released by discharging the brake fluid to A and 30B. When the driver releases the depression force on the brake pedal, the brake fluid stored in the reservoirs 30A and 30B is returned to the master cylinder 1 side by opening the check valves 32a and 32b by the spring force of the built-in spring. . Therefore, the reservoirs 30A and 30B can be made almost empty and the hydraulic pressure in the wheel cylinders of the wheels can be made zero.

FIG. 4 shows an example in which both front wheels and both front wheels are connected to the two-system master cylinder 1 of the conventional example by the X piping method. In the figure, the piping is damaged in the pipeline 31a or 31b. If the brake fluid leaks, hydraulic pressure is no longer supplied to the wheel cylinders of the wheels connected to this system. Especially in FIG. 4, a hydraulic pump is not provided,
The brake fluid discharged from the wheel cylinders is discharged to the reservoir 30A or 30B due to the decrease in hydraulic pressure. If both systems are normal, proper anti-skid control is performed within the capacity of the reservoirs 30A and 30B, but if one system fails, the vehicle speed will be the maximum wheel speed of the four wheels. Or when approximating the vehicle body speed with the second wheel speed, if this is used as the reference speed, the wheel of the normal system receives the brake slack signal even if the wheel speed slightly decreases, Drain the brake fluid into the reservoir of that system. As a result, the anti-skid control is performed, but the brake fluid is supplied by depressing the pedal 2 from the master cylinder 1 in order to discharge the brake fluid to the reservoir 30A or 30B each time the brake slack command is received. The piston connected to the brake pedal 2 must be depressed in the cylinder body 4 until it comes into contact with or comes close to its end wall, and finally no brake is applied.

Conventionally, in order to detect such a failure of the pipeline, Japanese Patent Application Laid-Open No. 8-91200 is provided with a failure detection device between two systems, which is a plunger for receiving hydraulic pressure of both systems. When one of the systems fails, it receives the hydraulic pressure of the normal system and moves to this failure side. As a result, it is detected that one of the systems has failed due to the movement of the detection rod connected to the plunger.

However, in such a method, a mechanical structure must be incorporated in both brake conduits, and in order to detect the structure between them and the brake pipe, or for surely detecting this structure, this failure occurs. It is necessary to detect the difference between the hydraulic pressure in the piping and the hydraulic pressure in the normal system by moving the plunger, which complicates the entire device, and also causes the control circuit to convert the movement of the connected detection rod into an electric signal. hand,
We have to do proper control. As a result, the cost of the device is increased, and the accuracy of detecting the failure is not satisfactory.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is a vehicle anti-apparatus that can detect a failure of a pipe of one system at a low cost in a quick and reliable manner. An object of the present invention is to provide a brake failure detection method for a skid hydraulic pressure control device and a device therefor.

[0011]

The above-mentioned problems are solved by an anti-skid liquid provided with an anti-skid hydraulic pressure control valve device for controlling the brake hydraulic pressure of a wheel cylinder of a wheel connected to one of the two-system master cylinders. In the pressure control method, (A) detecting that only the wheel cylinders of the wheels of one system are anti-skid controlled; and (B) the wheel speeds of the wheels of the system that are not anti-skid controlled are both predetermined. A method for detecting a brake failure of an anti-skid hydraulic pressure control device for a vehicle, wherein the system detecting (B) is determined to be defective by detecting that it is within the range. It

Alternatively, an anti-skid hydraulic pressure control valve device for controlling a brake hydraulic pressure of a wheel cylinder of a wheel connected to one of the two-system master cylinders, a sensor for detecting a wheel speed of the wheel, and a sensor for detecting the wheel speed of the wheel. In an anti-skid hydraulic pressure control device provided with the anti-skid hydraulic pressure control valve for receiving an output and a control unit for controlling the control device, (A) by the control unit, only the wheel cylinders of wheels of one system are subjected to anti-skid control And (B) detecting that the wheel speeds of the wheels that are not anti-skid controlled by the control unit are both within a predetermined range, thereby detecting (B). Anti-skid hydraulic control for vehicles characterized by determining that the system that has failed Brake failure detection device of the apparatus,
Will be solved by.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a flowchart showing a brake failure detection program according to a first embodiment of the present invention (front and rear separated pipes).
In step B, it is detected whether or not the brake pedal is depressed, and if YES, it is determined in step C whether only one system is under ABS control, and if YES, then in step D the vehicle speed is lower than the set minimum value. If it is YES, it is judged in step E whether the control is being performed for two cycles or more. That is, as shown in FIG. 3, the wheel speed V1 or V2 is decreasing or increasing. At this time, the brake fluid is discharged to the reservoir by opening the solenoid valve, and the wheel speed is judged by the control unit. If it is sufficiently recovered, it is increased as shown in FIG. 3, but in this embodiment, one cycle from the first brake slack command to the next slack command is started. Therefore, the two cycles or more means that the brake slack command is issued twice or more.

Next, in step F, it is judged whether the wheel speed which is not under control is within a predetermined range. That is, in FIG. 3, since the front-rear piping system is used now, if the brake piping of the front wheel system is lost, these are not ABS controlled, so that they are dependent on the vehicle body speed and as shown by V3 and V4.ゞ It will decrease as well. The braking force is 0
Or very small, but slightly less than each other in their wheel speeds. This difference is within the predetermined range W
Therefore, it is certainly decided that these front wheel systems have failed brakes. If YES in step F, it is determined in step G whether front wheel control is in progress. If YES here, it means that the rear wheel side is not controlled, so that the counter is started at step H by this, and when the counter time T becomes longer than the predetermined time T ₀ (step I),
In step J, a failure, that is, a leak flag is set. On the other hand, if the answer is NO in the front wheel control, it is determined in step K whether the vehicle body deceleration is less than 0.4 g. Y
In the case of ES, the counter is started at step H, but in the front and rear pipes as well, generally, a pressure reducing proportional valve is provided on the rear wheel side, or EBD control is performed to make the braking force smaller than that of the front wheel. Therefore, if it is less than 0.4 g, it means that the front wheel side has failed, and if pressure reduction proportional control or EBD control is being performed, it can be said that the front wheel side has failed. Since the ABS control may be temporarily performed during the period, in order to further ensure this detection control, it is determined in step K whether the vehicle deceleration is less than 0.4 g. Use H to count up. If NO, the front wheel side is normal and sufficient braking force is being generated, so the counter is cleared at stage L and the leak flag is reset at stage M. Stage N
The control ends with.

Although this embodiment is applied to the front and rear piping system, it is possible to reliably detect the failure of any system, and take appropriate measures. For example, the ABS control is stopped, or the driver is notified that a failure has occurred.

FIG. 2 is a flowchart of brake failure detection according to the second embodiment (X-pipe) of the present invention.
In the figure, control starts at stage O, and at stage P, the X piping system is used, but it is determined whether or not only one system is under ABS control. If YES, in step Q, it is determined whether the vehicle speed is higher than the set minimum value. If YES, in step R it is determined whether the vehicle body deceleration is less than 0.5 g. That is, if one of the systems has a brake failure,
This is because a deceleration of 0.5 g or more cannot be obtained. In step S, it is determined whether the ABS control is in control for two cycles or more. This is performed in the same manner as the case of using the front and rear separation type piping shown in FIG. If YES, in step T it is determined whether the wheel speed of the wheel that is not in control is within a predetermined range. This is also as described in the first embodiment,
If there is a failure in the wheel of the system that failed, for example, the pipe connecting the right front wheel and the left rear wheel in the present embodiment, these wheels will not be braked, so the wheel speeds are almost the same. If it is within the predetermined range, it is determined that the failure has occurred. Therefore, if YES in this step, the counter is started in step U, and if the counter time T becomes longer than the predetermined time T ₀ , the leak flag is set in step W.

On the other hand, if NO in each of the stages P to T, the counter is cleared in the stage X and the leak flag is reset in the stage Y. Control ends at step Z.

As described above, since the hydraulic pressure difference between the two systems is not mechanically detected by the signal from the control unit as in the conventional case, there is no need to add a structure for detecting a failure. The failure can be detected by using the conventional anti-skid control circuit as it is.

Although the embodiments of the present invention have been described above, the present invention is not limited to these, and various modifications can be made based on the technical idea of the present invention.

For example, in the above embodiment, in the front / rear separated pipe, it is determined in step B whether the vehicle speed is higher than the set minimum value.
Further, the failure detection method of the present invention can be realized without omitting the next step, that is, whether or not the control is being performed for two cycles or more.

Further, although the threshold values are set to 0.4 g and 0.5 g in the above-mentioned stage I and stage R, respectively, these can be variously changed according to the vehicle type. The same applies to the predetermined time and the counter time T ₀ . The present invention is of course applicable to an anti-skid control device using a hydraulic pump.

[0022]

As described above, according to the brake failure detection method for a vehicle anti-skid hydraulic pressure control device of the present invention and the device, a vehicle anti-skid hydraulic pressure control device having two brake systems is provided. A brake failure can be detected immediately and reliably.

[Brief description of drawings]

FIG. 1 is a flowchart of a program in which a brake failure detection method according to a first embodiment of the present invention is set in a computer (control unit).

FIG. 2 is a flowchart according to a second embodiment of the present invention.

FIG. 3 is a chart showing a change over time in the speed of a wheel showing the operation of the present invention.

FIG. 4 is a piping system diagram of an X piping system of an anti-skid control device that does not use a hydraulic pump to which the embodiment of the present invention is applied.

[Explanation of symbols]

1 master cylinder FR wheels RL wheels RR wheels FL wheels

Claims (10)

[Claims] 1. A brake failure detection of an anti-skid hydraulic pressure control device for a vehicle provided with an anti-skid hydraulic pressure control valve device for controlling a brake hydraulic pressure of a wheel cylinder of a wheel connected to each system of a two-system master cylinder. In the method, (A) detecting that only the wheel cylinders of the wheels of one system are anti-skid controlled; and (B) the wheel speeds of the wheels of the other system that are not anti-skid controlled are both predetermined. A method for detecting a brake failure of an anti-skid hydraulic pressure control device for a vehicle, comprising the step of detecting that it is within a range, and determining that the system that has detected (B) is failed. 2. The brake failure detection method for a vehicle anti-skid hydraulic pressure control device according to claim 1, wherein the anti-skid control is performed for two cycles or more. 3. The brake failure detection method for a vehicle anti-skid hydraulic pressure control device according to claim 1, wherein the vehicle body speed is equal to or higher than a minimum set value. 4. The wheel is connected to the two-system master cylinder by a front-rear separated piping system, and when the wheel deceleration is below a predetermined value, it is determined that the front-wheel system has failed. A method for detecting a brake failure of a vehicle anti-skid hydraulic pressure control device according to any one of claims 1 to 3. 5. The vehicle according to claim 1, wherein the wheels are connected to a two-system master cylinder by an X piping method, and a vehicle body deceleration is lower than a set minimum value. Brake failure detection method for anti-skid hydraulic pressure control device for automobile. 6. An anti-skid hydraulic pressure control valve device for controlling a brake hydraulic pressure of a wheel cylinder of a wheel connected to each system of a two-system master cylinder, a sensor for detecting a wheel speed of the wheel, and a sensor for detecting the wheel speed of the wheel. A brake failure detection device for a vehicle anti-skid hydraulic pressure control device provided with a control unit for receiving the output and controlling the anti-skid hydraulic pressure control device, comprising: (A) a wheel of a wheel of one system by the control unit. Means for detecting that only the cylinder is anti-skid controlled; and (B) means for detecting that the wheel speeds of the wheels that are not anti-skid controlled by the control unit are both within a predetermined range. The vehicle system characterized by determining that the system detecting (B) is defective. Brake failure detection device of the skid fluid pressure control apparatus. 7. The brake failure detection device for a vehicle anti-skid hydraulic pressure control device according to claim 6, wherein the anti-skid control is performed for two cycles or more. 8. The brake failure detection device for a vehicle anti-skid hydraulic pressure control device according to claim 6 or 7, wherein the vehicle body speed is equal to or higher than a minimum set value. 9. The wheel is connected to the two-system master cylinder by a front-rear separated piping system, and when the wheel deceleration is below a predetermined value, it is determined that the front-wheel system has failed. The brake failure detection device for a vehicle anti-skid hydraulic pressure control device according to any one of claims 6 to 8. 10. The vehicle according to claim 6, wherein the wheels are connected to a two-system master cylinder by an X piping method, and a vehicle body deceleration is lower than a set minimum value. Brake failure detection device for anti-skid hydraulic pressure control device.