JPH11278238A - Internal liquid leakage detecting device for brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably detect by a low-cost method when brake fluid leaks to the outside of a design spot in the hydraulic control unit of a brake device for a vehicle to keep a brake hydraulic pressure at a proper value by effecting electronic control. SOLUTION: In a brake device, as shown in Fig, to effect pressure reduction and re-pressurization of a wheel cylinder 3 by a command from an electronic control device 10 when occasion demands, when a solenoid value 6 is opened when it is to be closed, brake fluid from a master cylinder 2 also flows to a buffer chamber 8 in a hydraulic control unit 11 and reduction of a pressure through electronic control is rendered impossible. Thereby, an internal part liquid leakage detecting device is provided to have a stroke sensor 13 to detect the position of a brake pedal and a pressure sensor 14 to detect a brake liquid pressure. When detecting signals from the sensors 13 and 14 do not satisfy a predetermined given relation, an abnormal signal is outputted and an alarm apparatus 15 is operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting internal fluid leakage of a brake hydraulic circuit used in a brake device having an electronically controlled brake system, and a vehicle brake device provided with the same to enhance safety.

[0002]

2. Description of the Related Art In recent years, in an electronically controlled brake system, which has become very popular for improving vehicle safety, a brake fluid is temporarily applied to a design portion in a hydraulic control unit due to a failure of a valve for opening and closing a flow passage. There is a possibility that a situation other than movement (internal liquid leakage) may occur.

For example, in an anti-lock brake system (shown in FIG. 6) exemplified in Japanese Patent Application Laid-Open No. 8-142,836, when the anti-lock pressure is reduced when the solenoid valve 5 is closed and the valve 6 is opened, the wheel cylinder 3 is turned off. The discharged brake fluid is transferred to the buffer chamber 8 in the hydraulic pressure control unit 11.
When the anti-lock is repressurized (at this time, the solenoid valve 5 is opened and the solenoid valve 6 is closed), it is pumped up by the pump 7 and supplied to the wheel cylinder 3. When a trouble occurs that the solenoid valve 6 cannot be closed mechanically even though no opening command is issued to the normally closed (normally closed) solenoid valve 6, the driver depresses the brake pedal 1. Then, the brake fluid to be supplied to the wheel cylinder 3 also flows into the buffer chamber 8. As a result, when the buffer chamber 8 is full and a decompression command is issued, there is no destination for the discharged liquid, and decompression becomes impossible.

In recent years, devices that can perform not only antilock control but also yaw control (for example, devices disclosed in Japanese Patent Application Laid-Open Nos. 3-112755 and 5-221300) have appeared. Equipment such as
Depending on the capacity of the reservoir (buffer chamber) that receives the discharged brake fluid when the wheel cylinder is depressurized, a problem that the pressure cannot be depressed due to internal fluid leakage may occur.

Further, the apparatus disclosed in Japanese Patent Application Laid-Open Nos. 3-112755 and 5-221300 for performing yaw control is characterized in that, during normal control, a flow path between a master cylinder and a wheel cylinder is provided with a pressure-sensitive cut valve or electromagnetic valve. Directly or indirectly to the wheel cylinder by shutting off with a switching valve and controlling the hydraulic pressure from the power driven hydraulic pressure source to a value corresponding to the operation input (the force applied to the brake pedal by the driver) by the electromagnetic proportional pressure control valve However, if the internal fluid leaks, the correspondence between the operation input and the actual brake fluid pressure is deteriorated, and the control may be disturbed.

[0006] Therefore, in an electronically controlled brake system, it is desired to detect an internal liquid leak so that a response can be taken as soon as possible.

[0007] To meet the demand, Japanese Utility Model Application
There is a brake device disclosed in Japanese Patent No. 60664. This brake device detects a change in the volume of the buffer chamber (reservoir tank) during normal braking by detecting means such as a contact type sensor in order to detect internal liquid leakage.

[0008]

[Problems to be Solved by the Invention]
In the brake device disclosed in the publication, a sensor for detecting a change in volume is incorporated in the buffer chamber in the hydraulic unit, so that the buffer chamber becomes complicated, the manufacturing becomes complicated, the number of parts increases, and the cost increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a device capable of reliably detecting a liquid leak in an electronically controlled brake device by an economically advantageous method.

Further, when the internal fluid leaks, the brake fluid pressure obtained when the brake pedal is depressed by a certain amount becomes lower than in a normal condition, which may cause a decrease in braking force and a deterioration in pedal feeling. Therefore, the present invention also provides a brake device that solves this problem by using the internal liquid leakage detection device of the present invention.

[0011]

As a solution to the above-mentioned problems, the present invention provides the following internal liquid leak detecting device.

In the internal liquid leakage detecting device, the electronic control unit determines the necessity of increasing / decreasing the pressure of the wheel cylinder based on information from a sensor group including the brake pressure detecting means, and receives a pressure reduction command from the electronic control unit. Apparatus for adding a brake fluid for pressurizing a wheel cylinder to a vehicle brake device having a function of temporarily moving the brake fluid out of a main flow path, comprising: means for detecting a position of a brake pedal; and means for detecting the position of the brake pedal. A circuit for determining whether a relationship between a brake pedal position and a brake pressure detected by the brake pressure detecting means satisfies a predetermined relationship, and generating an abnormal signal when the relationship is not satisfied; It comprises.

Some of the electronically controlled vehicle brake devices can variably control a braking force obtained in response to an input applied by a driver. For example, a pedaling force or a pedal stroke applied to a brake pedal is detected and input to an electronic control unit, and an input signal is supplied to a pressure regulating valve (for example, an electromagnetic proportional pressure control valve) which performs pressure control according to an electric command from the electronic control unit. In the brake device of the type that regulates the wheel cylinder pressure by passing an electric command according to the above, when the output gain with respect to the input is changed by control software, the obtained braking force changes.

The above-described internal fluid leakage detection device is added to this type of brake device, and when an abnormal signal is output from the internal fluid leakage detection device, the control mode of the brake fluid pressure by the electronic control device is changed to the input mode. If the output gain is switched to a value larger than that in the case where there is no abnormal signal, it is possible to prevent a decrease in the braking force and the like due to internal liquid leakage.

[0015]

When the internal fluid leaks in the brake device, the brake pressure obtained when the brake pedal is depressed to a certain position is reduced as compared with the normal operation. Therefore, whether or not the internal liquid leakage has occurred can be reliably detected based on whether or not the relationship between the position of the brake pedal and the brake pressure satisfies a predetermined relationship (the relationship at the time of normal operation).

If the abnormality detected in this way is notified to the driver by an alarm, the driver can perform the brake operation in consideration of the fact that the pressure reduction by the electronic control is not performed, and the failure can occur. Will not be left uninformed.

Here, JP-A-5-22130 mentioned above
No. 0 publication detects the brake pressure as information for judging pressurization and decompression by the electronic control unit.
A pressure sensor for that purpose is provided as an essential element.
Further, some of them include a pedaling force sensor which can be a position detecting means of the brake pedal. Since the internal liquid leak detecting device of the present invention can use the pressure sensor, the pedaling force sensor, and the like originally provided in the brake device to be adopted, it is more advantageous in cost than the detecting device disclosed in Japanese Utility Model Laid-Open No. 4-60764.

When the present invention is applied to the apparatus disclosed in Japanese Patent Application Laid-Open No. 3-112755, the position of the brake pedal can be detected using a pressure sensor provided between the master cylinder and the cut valve. (The output of the sensor is approximately proportional to the amount of depression of the brake pedal.) Therefore, in this case, it is only necessary to add a pressure sensor for detecting the wheel cylinder pressure.
This is advantageous in terms of cost as compared with the detection device of JP-A-64.

A brake device in which the relationship between the input and the obtained braking force is variable and the control mode of the hydraulic pressure is switched to a mode in which the output gain is made larger than that in the normal state when an abnormality is detected is an internal liquid leakage. Since the amount of fluid replacement from the pump circuit at the time of occurrence increases, the amount of fluid leakage is compensated for by the increased amount of fluid replacement, thereby preventing a reduction in braking force and deterioration in pedal feeling.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of a brake device employing an internal liquid leak detecting device according to the present invention.
In the figure, 1 is a brake pedal, 2 is a master cylinder, 3 is a wheel cylinder, 4 is a main flow path from the master cylinder 2 to the wheel cylinder 3, 5 and 6 are solenoid valves for opening and closing the flow path, 7 is a power-driven pump, 8 is a buffer chamber, 9
Is a wheel speed sensor, 10 is an electronic control unit, 11 is a hydraulic control unit, 12 is a reservoir mounted on the master cylinder 2, 13 is a stroke sensor for detecting the position of the brake pedal, and 14 is the generated brake pressure (in the case of the figure). , Brake fluid pressure), and 15 is an alarm.

The wheel cylinder 3, the solenoid valve 5,
6, only the wheel speed sensor 9 is provided in a one-wheel system. Either one or both of the solenoid valves 5 and 6 may be replaced by a pressure regulating valve capable of continuous pressure control.

When the electronic control unit 10 detects a sign of wheel lock based on information from the wheel speed sensor 9 in a normal state, the brake device issues a close command to the solenoid valve 5 and an open command to the solenoid valve 6 so that the wheel cylinder 3 Is reduced. When the wheel shows a sign of recovery from the lock due to the pressure reduction, the solenoid valve 5 is opened, the valve 6 is returned to the closed state, and the pressure is re-pressurized by the pressure introduced from the pump 7, and the operation is repeated to lock the wheel lock. Be avoided.

When the solenoid valve 6 cannot be closed due to some trouble and the brake is applied in this state and the brake fluid from the master cylinder 2 leaks toward the buffer chamber 8, the fluid is The leak is detected by a detection device constituted by the stroke sensor 13, the pressure sensor 14 and a circuit in the electronic control device 10.

First, the stroke amount of the brake pedal 1 is detected by the stroke sensor 13, the generated brake fluid pressure is detected by the pressure sensor 14, and each detection signal is input to the electronic control unit 10. .

Next, the electronic control unit 10 checks the relationship between the input stroke signal and the hydraulic pressure signal, and determines whether or not the relationship is a predetermined relationship (normal relationship). FIG. 3 shows an example of a control flow relating to the determination.
Here, the ratio (for example, Q = Si / Pi) of the stroke signal Si and the hydraulic pressure signal Pi is calculated and calculated, and when the ratio Q exceeds the set value N, Si and Pi satisfy a predetermined relationship. It is concluded that there is no abnormal signal, and the output circuit of the abnormal signal is turned on, and the abnormal signal is output therefrom. In the brake device shown in FIG. 1, the alarm 15 is activated by the abnormality signal to notify the driver of the abnormality.

When the internal liquid leaks into the buffer chamber 8, the pressure reduction by the electronic control becomes impossible. Therefore, it is preferable to stop the antilock control.

The brake device shown in FIG. 1 has been described by way of example for general anti-lock control in order to make the description easy to understand. In this brake device, for example, a solenoid valve 5 shown in the figure is a normally closed (normally closed) valve, and a cut valve for closing the main flow path 4 between the pressure sensor 14 and the master cylinder 2 shown in FIG. When the accumulator is inserted and the accumulator is further inserted into the discharge circuit of the pump 7, automatic braking can be applied by a command from the electronic control unit 10, and control such as yaw control and traction control can be performed. Depending on the contents of the control, the pressure sensor 14 and the stroke sensor 13 (which may be replaced by a treading force sensor or the like) are essential elements. The brake device according to the present invention is advantageous in terms of cost since it detects internal liquid leakage using the brake device.

FIG. 2 shows an example of a brake device according to a second embodiment in which a braking force obtained for an input can be arbitrarily changed by control software.

Here, a pressure regulating valve 16 for wheel cylinder pressure is provided in place of the solenoid valve 6 in FIG. 1, and a normally closed solenoid valve 17 and a master cylinder pressure regulating valve are provided between the main flow path 4 and the reservoir 12. A pressure valve 18 is provided in series, and an accumulator 19 is added to the discharge circuit of the pump 7.

The pressure regulating valve 16 is an electromagnetic proportional pressure control valve (a type in which the passage between the wheel cylinder 3 and the pump 7 and the passage between the wheel cylinder 3 and the buffer chamber 8 are both closed when not in operation). Based on output signals from a sensor group for detecting the behavior (wheel speed sensor, acceleration sensor, yaw sensor, etc., all of which are not shown), the wheel cylinder 3 receives a pressure regulation command from an electronic control unit (not shown) when necessary. Is controlled to a value corresponding to the electric command amount (current value flowing through the driving electromagnet).

The pressure regulating valve 18 controls the brake fluid pressure (master cylinder pressure) generated in the main flow path 4 to a value corresponding to the output of the stroke sensor 13. FIG. 4 is an example of an electromagnetic proportional pressure control valve used as the pressure regulating valve 18. This electromagnetic proportional pressure control valve has been proposed by the present applicant, and has a spool 3 inserted into the housing 30.
1 is the force applied upward (driving force by electromagnet 34)
To the balance point of the downwardly applied force (the force obtained by adding the force of the spring 33 and the thrust Fpr due to the hydraulic pressure), and the connection of the load port 36 to the input port 35 and the discharge port 37 is switched by the spool movement. A first port for opening and closing a passage between the input port 35 and the load port 36;
The opening of the valve portion 38 and the second valve portion 39 that opens and closes the passage between the discharge port 37 and the load port 36 are also adjusted, so that the load port 3
6 (master cylinder pressure) is smoothly and continuously controlled so as to be a function of the current I flowing through the electromagnet 34.

The above-mentioned Fpr is a fluid chamber 40 for communicating the fluid pressure of the input port 35 with the reservoir P12 in FIG.
Assuming that the hydraulic pressure of P41 is P3 and the cross-sectional area of the reaction force pin 32 is S, it can be obtained by the equation (P2-P3) · S.

The electromagnetic proportional pressure control valve of FIG. 4 can also be used as the pressure regulating valve 16 if the initial position of the spool 31 is set to a position where both the first valve portion 38 and the second valve portion 39 are closed.

In the brake device of FIG. 2, the output gain with respect to the driver's input (the output of the stroke sensor 13) can be freely changed by control software, and the change in the gain changes the current flowing through the electromagnet of the pressure regulating valve 18. The obtained braking force changes.

In the brake device shown in FIG. 2, if the pressure regulating valve 16 is not closed when it should be closed, the internal fluid leakage detecting device similar to that described with reference to FIG. Circuit for generating an abnormal signal when detected (not shown)
Outputs an abnormal signal.

When this abnormal signal is output, the control mode of the master cylinder pressure by the pressure regulating valve 18 is switched to a mode in which the output gain with respect to the input is increased as compared with the case where there is no abnormal signal. The amount of the introduced liquid is increased as compared with the normal state, and a decrease in the braking force and an increase in the pedal stroke are prevented or suppressed.

The brake device shown in FIG.
And the pressure regulating valve 18 may be omitted. An example is shown in FIG.
Shown in In the figure, reference numeral 21 denotes a stroke simulator provided as needed.

In this brake device, when the brake pedal 1 is depressed, the main flow path 4 is closed by the solenoid valve 5,
The switching cylinder 20 connects the wheel cylinder 3 to the pressure regulating valve 23. The pressure regulating valve 23 is an electromagnetic proportional pressure control valve as described in FIG. 4. The pressure regulating valve 23 regulates the pressure so that the brake fluid pressure of the discharge circuit of the pump 7 becomes a value corresponding to the output of the stroke sensor 13. Being wheel cylinder 3
Supplied to The brake fluid pressure after pressure regulation may be supplied directly to the wheel cylinder 3 or indirectly via a cylinder 22 that makes the system on the pump 7 side and the system on the master cylinder 2 side independent.

In the brake device shown in FIG. 5, when a fluid leaks inside the pressure regulating valve 23 when the pressure regulating valve 23 operates normally (the spool valve type pressure regulating valve has a large sliding clearance for the spool, etc.). Such a case may occur), the output of the stroke sensor 13 and the pressure sensor 1
The output of No. 4 does not satisfy the predetermined relationship, whereby an internal liquid leak is detected. Further, the pressure regulating valve 23 whose output gain with respect to the input is higher than that in the normal state is driven, and a higher hydraulic pressure than in the normal state is supplied to the wheel cylinder 3, so that a decrease in the braking force is suppressed.

When the pressure of the wheel cylinder 3 is increased or decreased by electronic control, the stroke sensor 1
Since the relationship between the output of the pressure sensor 14 and the output of the pressure sensor 14 may deviate from the predetermined relationship, the determination of the internal liquid leak is performed when the pressure is not increased or reduced by the electronic control.

[0041]

As described above, the use of the fluid leakage detecting device of the present invention makes it possible to reliably detect the leakage of the brake fluid in the fluid pressure control unit by using the pressure sensor or the like originally provided in the braking device. It helps to increase the safety of the vehicle brake system economically.

Further, when an abnormal signal is generated, the brake device in which the control mode of the brake fluid pressure is switched to a mode in which the output gain with respect to the input is increased as compared with the case where there is no abnormal signal is controlled by internal fluid leakage. Deterioration of pedal feeling due to a decrease in power and an increase in pedal stroke can also be suppressed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a brake device according to a first embodiment.

FIG. 2 is a circuit diagram of a brake device according to a second embodiment.

FIG. 3 is a flowchart showing an example of internal liquid leak detection.

FIG. 4 is a sectional view showing a specific example of an electromagnetic proportional pressure control valve employed as the pressure regulating valve 18.

FIG. 5 is a circuit diagram of a brake device according to a third embodiment.

FIG. 6 is a circuit diagram of a conventional example of an electronic control brake device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brake pedal 2 Master cylinder 3 Wheel cylinder 4 Main flow path 5, 6, 17 Solenoid valve 7 Pump 8 Buffer chamber 9 Wheel speed sensor 10 Electronic control unit 11 Hydraulic pressure control unit 12 Reservoir 13 Stroke sensor 14 Pressure sensor 15 Alarm 16, 18, 23 Pressure regulator 19 Accumulator 20 Switching valve 21 Stroke simulator 22 Cylinder 30 Housing 31 Spool 32 Reaction pin 33 Spring 34 Electromagnet 35 Input port 36 Load port 37 Discharge port 38 First valve section 39 Second valve section 40, 41 Liquid chamber

Claims (2)

[Claims] An electronic control unit determines the necessity of pressurizing and depressurizing a wheel cylinder on the basis of information from a sensor group including a brake pressure detecting means. Apparatus for adding to a vehicle brake device having a function of temporarily moving liquid out of a main flow path, comprising: means for detecting a position of a brake pedal; position detection means for the brake pedal; and said brake pressure detection means Circuit that determines whether or not the relationship between the brake pedal position and the brake pressure detected by the ECU satisfies a predetermined relationship, and generates an abnormal signal when the relationship is not satisfied. Internal leak detection device. 2. A vehicle brake device capable of changing a braking force obtained in response to an input applied by a driver under the control of an electronic control unit, comprising a device for detecting an internal liquid leak according to claim 1. When an abnormal signal is output from the internal liquid leak detection device, the control mode of the brake fluid pressure by the electronic control unit switches to a mode in which the output gain for the input is made larger than when there is no abnormal signal. Vehicle brake device.