JP2006001402A - Brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake control device which can achieve early detection of irregularities. <P>SOLUTION: The brake control device is provided with a source of hydraulic pressure, a hydraulic pressure sensor, a plurality of switching valves, a means of controlling pressure, and a means of detecting irregularities. The source of hydraulic pressure supplies brake hydraulic pressure to a wheel cylinder based on an output signal from a control unit. Then the hydraulic pressure sensor detects a hydraulic pressure within the wheel cylinder, and the plurality of switching valves switch oil pathways to increase, retain and reduce the hydraulic pressure conditions within the wheel cylinder. Then the means of controlling pressure switches the hydraulic pressure conditions within the wheel cylinder by a predetermined pattern comprising a combination of a pressure increase, pressure retention and reduction regardless of the operation of a brake pedal. Then the means of detecting irregularities detects the irregularities of the hydraulic pressure sensor or the switching valve based on whether or not the hydraulic pressure conditions in accordance with the predetermined pattern have been obtained at the time when an ignition is on. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a brake control device, and more particularly to a technique for detecting an abnormality in a sensor, a solenoid valve, or the like.

Conventionally, a technique described in Patent Document 1 has been disclosed as an abnormality detection unit of a brake control device. In this publication, an abnormality of the pressure sensor is detected when hydraulic pressure acts on the wheel cylinder by operating the brake pedal during traveling.
JP-A-8-292112.

  However, in the above-described prior art, since the abnormality of the hydraulic pressure sensor is detected based on the brake hydraulic pressure generated by operating the brake pedal during traveling, the abnormality of the hydraulic pressure sensor is detected only when the brake pedal is actually depressed. There was a problem that detection could not be performed and the timing of abnormality detection was delayed.

  The present invention has been made paying attention to the above-described conventional problems, and an object of the present invention is to provide a brake control device that can achieve abnormality detection at an early stage.

  In order to achieve the above object, the present invention provides a hydraulic pressure generating source for supplying brake hydraulic pressure to the wheel cylinder based on an output signal from the control unit, a hydraulic pressure sensor for detecting the hydraulic pressure in the wheel cylinder, Multiple switching valves that switch the oil path to increase, hold, and reduce the hydraulic pressure in the wheel cylinder, and increase, hold, and reduce the hydraulic pressure in the wheel cylinder regardless of brake pedal operation. Pressure control means for switching in a predetermined pattern consisting of a combination, and abnormality detection for detecting an abnormality in the hydraulic pressure sensor or the switching valve based on whether or not a hydraulic pressure state corresponding to the predetermined pattern is obtained when the ignition is turned on Means.

  Therefore, it is possible to detect an abnormality in the hydraulic pressure sensor or the switching valve when the ignition is turned on before the vehicle starts running.

  The best mode for carrying out the present invention will be described below with reference to the drawings as an embodiment.

  FIG. 1 is a schematic diagram (mainly a circuit configuration of a rear wheel hydraulic pressure control unit) illustrating a configuration of the brake control device according to the first embodiment. First, the configuration will be described. A master cylinder 4 integrated with a reservoir tank 3 is connected to a brake pedal 1 operated by a driver via a booster 2 that assists pedal effort. The master cylinder 4 is a so-called tandem type, and supplies the same master cylinder pressure to the two brake paths 4a and 4b. Each of the brake paths 4a and 4b is provided with a hydraulic pressure sensor 5 for detecting the master cylinder pressure, and is input to the main control unit ECU. Further, on the brake paths 4a and 4b, a driver-integrated front wheel side hydraulic pressure control unit 100 capable of achieving the known ABS control, VDC control, TCS control, etc. is provided, and the wheels of the right front wheel FR and the left front wheel FL are provided. Connected to cylinder W / C.

  On the rear wheel side, a rear wheel hydraulic pressure control unit 10 including a hydraulic pressure source other than the master cylinder 4 and an electric brake unit 200 are provided. The rear wheel hydraulic pressure control unit 10 is configured to be able to achieve brake-by-wire control. During normal braking control, the main control unit ECU calculates the rear-wheel braking force according to the master cylinder pressure (front-wheel braking force) generated by the driver's operation of the brake pedal 1, and the electric brake unit 200, rear A command signal is output to the wheel side hydraulic pressure control unit 10. In addition, when ABS control, VDC control, TCS control or the like is executed, a command signal is output to the front wheel side hydraulic pressure control unit 100, the electric brake unit 200, and the rear wheel side hydraulic pressure control unit 10. Each wheel is provided with a wheel speed sensor 6 for detecting the wheel speed, and outputs a wheel speed signal to the main control unit ECU.

  FIG. 2 is a circuit diagram illustrating a configuration of the rear wheel side hydraulic pressure control unit 10. The rear wheel side hydraulic pressure control unit 10 is connected to the reservoir tank 3 via an oil passage 40. Oil paths 41, 42, 45L (R), 46L (R), which will be described later, are connected to the oil path 40, respectively. A normally closed ON-OFF control type left in-side gate valve 11 is provided on the oil passage 41 and between the first plunger pump 17. A normally closed ON / OFF control type right-in side gate valve 12 is provided on the oil passage 42 and between the second plunger pump 18. In the first embodiment, both the first plunger pump 17 and the second plunger pump 18 have the same capacity and are driven by the same motor 19.

  The downstream side of the first plunger pump 17 and the second plunger pump 18 is connected to the oil passage 43. On the oil passage 43, a normally open ON / OFF control type isolation valve 24 is provided.

  A normally open proportional control type in-valve 27L is provided between the oil passage 43 and the oil passage 43L connected to the wheel cylinder W / C on the left rear wheel side in the left rear wheel side system. A hydraulic pressure sensor 29L that detects the wheel cylinder pressure of the left rear wheel is provided in the oil passage 43L. Further, between the oil passage 45L connected to the oil passage 40 and the oil passage 43L, a normally closed ON-OFF control type out valve 30L is provided. Between the oil passage 43 and the oil passage 40, a left drain oil passage 46L connected via a normally open proportional control type out-side gate valve 31L is provided.

  A normally open proportional control type in-valve 27R is provided between the oil passage 43 and the oil passage 43R connected to the right rear wheel side wheel cylinder W / C. The oil passage 43R is provided with a hydraulic pressure sensor 29R for detecting the wheel cylinder pressure of the right rear wheel. Further, a normally closed ON-OFF control type out valve 30R is provided between the oil passage 45R connected to the oil passage 40 and the oil passage 43R. Between the oil passage 43 and the oil passage 40, a right drain oil passage 46R connected via a normally open proportional control type out-side gate valve 31R is provided.

(Hydraulic pressure control action)
Next, the hydraulic pressure control operation based on the circuit configuration will be described. The rear wheel wheel cylinder pressure increase / decrease control is performed by reducing the drive amount of the motor 19 at the time of increase in accordance with the deviation between the calculated target hydraulic pressure and the actual hydraulic pressure detected by the hydraulic pressure sensors 29L and 29R. Sometimes, the valve operation amount of the out valves 30L, R or the out side gate valves 31L, R is controlled.

(Decompression action)
During brake-by-wire control, the wheel cylinder W / C is decompressed by proportionally controlling the out valves 31L and R. In addition, during ABS control or VDC control, the in-valves 27L and R are held, and at this time, the wheel cylinder W / C is depressurized by ON-OFF control of the out-valves 30L and R.

(Abnormality detection processing)
Next, the abnormality detection process of the present embodiment will be described. FIG. 3 is a flowchart showing the main flow of the abnormality detection process. This control process is performed when the ignition is turned on.

In step 101, the brake state is captured.
In step 102, it is determined whether or not the brake is OFF. If the brake is ON, this control flow is terminated. Otherwise, the process proceeds to step 103.
In step 103, the wheel speed detected by the wheel speed sensor 6 is read.
In step 104, it is determined whether or not the vehicle is stopped based on the read wheel speed. If the vehicle is stopped, the process proceeds to step 105. Otherwise, the control flow ends.
In step 105, drive pattern processing is started. Details of the process will be described later.
In step 106, it is determined whether or not an abnormality has been detected. When an abnormality is detected, the system is shut down, and otherwise the control is terminated.

(Drive pattern processing)
Next, drive pattern processing in step 105 will be described. 4 and 5 are flowcharts showing drive pattern processing.

(Drive pattern S1)
In step 108, the drive pattern of S1 is started. Details of the drive pattern will be described later.
In step 109, the wheel cylinder pressure of each wheel is read.
In step 110, it is determined whether or not the wheel cylinder pressure is larger than the reference value Pm. If the wheel cylinder pressure is larger, the process proceeds to step 111. Otherwise, the process proceeds to step 112.
In step 111, it is detected that the in valves 27L, R or the left and right in-side gate valves 11, 12 are abnormal.

(Drive pattern S2)
In step 112, the drive pattern of S2 is started. Details of the drive pattern will be described later.
In step 113, the pressure values of the hydraulic pressure sensors 29L and 29R are read.
In step 114, it is determined whether or not the pressure value is larger than the predetermined value Pm. If it is larger, the process proceeds to step 115. Otherwise, the process proceeds to step 116.
In step 115, an abnormality in the left and right in-side gate valves 11, 12 is detected.

(Drive pattern S3)
In step 116, the drive pattern of S3 is started. Details of the drive pattern will be described later.
In step 117, the pressure values of the hydraulic pressure sensors 29L and 29R are read.
In step 118, it is determined whether or not the pressure is increased. When it is determined that the pressure is increased, the process proceeds to step 119. Otherwise, the process proceeds to step 122.
In step 119, the inclination of the pressure increase of both wheels is calculated.
In step 120, it is determined whether or not the absolute value of the difference in inclination is larger than the predetermined value Pi. If larger, the process proceeds to step 121. Otherwise, the process proceeds to step 123.
In step 121, an abnormality in the out-side gate valves 31L and 31R or the hydraulic pressure sensors 29L and 29R is detected.
In step 122, this control flow is terminated as abnormality detection.

(Drive pattern S4)
In step 123, the drive pattern of S4 is started. Details of the drive pattern will be described later.
In step 124, the pressure values of the hydraulic pressure sensors 29L and 29R are read.
In step 125, it is determined whether or not the absolute value of the difference between the held values is larger than the predetermined value Phd. If it is larger, the process proceeds to step 126, and otherwise, the process proceeds to step 127.
In step 126, an abnormality in the in-side gate valves 11 and 12 is detected.

(Drive pattern S5)
In step 127, the drive pattern of S5 is started. Details of the drive pattern will be described later.
In step 128, the pressure values of the hydraulic pressure sensors 29L and 29R are read.
In step 129, the slopes of decompression of both wheels are calculated.
In step 130, it is determined whether or not the absolute value of the difference in inclination is larger than the predetermined value Pd. If it is larger, the process proceeds to step 131, and otherwise, the process proceeds to step 132.
In step 131, an abnormality in the out-side gate valves 31L and 31R is detected.

(Drive pattern S6)
In step 132, the drive pattern of S6 is started. Details of the drive pattern will be described later.
In step 133, the pressure values of the hydraulic pressure sensors 29L and 29R are read.
In step 134, it is determined whether the pressure is not reduced. If not, the process proceeds to step 135. Otherwise, the process proceeds to step 136.
In step 135, an abnormality in the out valves 30L and R is detected.
In step 136, it is determined that the operation is normal, and the control flow ends.

(About drive pattern)
Next, each driving pattern of S1 to S6 will be described. FIG. 6 is a diagram showing an operating combination of the in-side gate valves 11 and 12, the in-valves 27L and R, the out valves 30L and R, the out-side gate valves 31L and R, the isolation valve 24, and the motor 19 in each driving pattern. Each drive pattern is achieved by the combination shown in FIG. At this time, it is assumed that all the solenoid valves are normal when the ignition is switched from OFF to ON. In the first embodiment, the isolation valve 24 is always closed (ON state). FIG. 7 is a time chart showing drive pattern processing. Hereinafter, each drive pattern will be described in detail.

(Operation in drive pattern S1)
FIG. 8 is a diagram showing a rear wheel brake circuit in the drive pattern S1. In the drive pattern S1, the out-side gate valves 31L, R and the in-valves 27L, R are closed, and an ON signal is output and opened to the in-side gate valves 11, 12 in a state where a closed circuit is configured, and the motor 19 is driven by PWM control. Then, hydraulic pressure is generated. The in-valves 27L and R and the out-valves 31L and R, which are proportional control valves, are closed by a PWM control signal.

  As shown in FIG. 8, when hydraulic pressure is generated by driving the motor 19, the hydraulic pressure in the closed circuit increases. At this time, if each solenoid valve is operating normally, the pressure values of the hydraulic pressure sensors 29L and 29R will not increase. On the other hand, when the pressure values of the hydraulic pressure sensors 29L and R increase, it is considered that the hydraulic pressure has flowed out to the wheel cylinder side due to the abnormality of the in valves 27L and R, or the hydraulic pressure sensors 29L and R itself are abnormal. That is, when the pressure value exceeds the predetermined value Pm in the drive pattern S1, an abnormality of the in-valves 27L, R or an abnormality of the hydraulic pressure sensors 29L, R is detected.

(Operation in drive pattern S2)
FIG. 9 is a diagram showing a rear wheel brake circuit in the drive pattern S2. In the drive pattern S2, all the solenoid valves other than the in-valves 27L and R are closed, and the motor 19 is driven by PWM control. That is, a PWM control signal is sent to the out-side gate valves 31L and 31R as the electromagnetic valve drive signal. At this time, if each solenoid valve is operating normally, the in-side gate valves 11 and 12 are closed even if the pump is driven, and no hydraulic pressure is generated simply by idling, and the hydraulic pressure sensors 29L and 29L The pressure value does not increase. That is, it can be determined that the valve is operating normally when there is no hydraulic pressure difference upstream and downstream of the in-side gate valves 11 and 12.

  On the other hand, when the pressure values of the hydraulic pressure sensors 29L and 29R rise, it is considered that the in-side gate valves 11 and 12 are not closed and pressure increase by the pump is generated. That is, when the pressure value exceeds the predetermined value Pm in the drive pattern S2, an abnormality in the in-side gate valves 11 and 12 is detected.

(Operation in drive pattern S3)
FIG. 10 is a diagram showing a rear wheel brake circuit in the drive pattern S3. In the drive pattern S3, the in-valves 27L and R and the in-side gate valves 11 and 12 are opened, the other electromagnetic valves are closed, and the motor 19 is driven by PWM control. That is, an ON signal is output to the in-side gate valves 11 and 12 to open the electromagnetic valve drive signal, and a PWM control signal is output and closed to the out-side gate valves 31L and R.

At this time, the inclination of the pressure increase of both the hydraulic pressure sensors 29L and 29R is calculated, and if the difference between the inclinations is equal to or less than the predetermined value Pi, it is determined as normal. On the other hand, when the difference in inclination is larger than the predetermined value Pi,
1) Insufficient pump intake due to abnormality of in-side gate valves 11 and 12 2) Insufficient communication due to abnormality of in-valves 27L and R 3) Depressurization due to abnormality of out-valves 30L and R 4) Out-side gate valves 31L and R 5) Pressure sensor 29L, R may be abnormal. Here, the drive pattern S3 is performed only when the drive patterns S1 and S2 are normal. It is already known that the in-side gate valves 11 and 12 and the in-valves 27L and R are normal in a state where there is no fluid pressure difference, and it is assumed that the normally closed type out-valves 30L and R are normal. It can be determined that the gate valves 31L, R are abnormal or the hydraulic pressure sensors 29L, R are abnormal. When the pressure is not increased, it cannot be determined what is abnormal, but it is determined to be abnormal because there is some abnormality.

(Operation in drive pattern S4)
FIG. 11 is a diagram illustrating a rear wheel brake circuit in the drive pattern S4. In the drive pattern S4, only the in valves 27L and R are opened, the other solenoid valves are closed, and the drive of the motor 19 is also stopped. That is, as a drive signal for the solenoid valve, a PWM control signal is output to the out-side gate valves 31L and 31R and closed. When viewed from the drive pattern S3, the in-side gate valves 11 and 12 are only closed.

At this time, if the difference between the holding pressures of the two hydraulic pressure sensors 29L and 29R is equal to or smaller than the predetermined value Phd, it is determined that it is normal. On the other hand, when the difference in holding pressure is larger than the predetermined value Phd,
1) Pressure reduction due to leakage from the pump due to abnormality of the in-side gate valves 11 and 12 in a state where there is a hydraulic pressure difference 2) The possibility of pressure reduction due to abnormality of the out-side gate valves 31L and R is considered. Here, the drive pattern S4 is performed only when the drive patterns S1, S2, and S3 are normal. The in-side gate valves 11 and 12 in the state where no hydraulic pressure has already been generated are determined to be normal, and the in-valves 27L and R, the hydraulic pressure sensors 29L and R, the out valves 30L and R, and the out-side gate valves 31L and R Is known to be normal, it is possible to detect an abnormality in the in-side gate valves 11 and 12 in a state where there is a hydraulic pressure difference between the upstream and downstream.

(Operation in drive pattern S5)
FIG. 12 is a diagram illustrating a rear wheel side brake circuit in the drive pattern S5. In the drive pattern S5, the in-valves 27L, R and the out-side gate valves 31L, R are opened by PWM control, the other electromagnetic valves are closed, and the drive of the motor 19 is also stopped. That is, as a drive signal for the solenoid valve, a PWM control signal is output to the out-side gate valves 31L and 31R to start decompression. When viewed from the drive pattern S4, only the hydraulic pressure leaks from the out-side gate valves 31L and 31R.

  At this time, if the difference between the inclinations of the pressure reductions of both the hydraulic pressure sensors 29L and 29R is equal to or smaller than the predetermined value Pd, it is determined as normal. On the other hand, when the difference in the pressure reduction gradient is larger than the predetermined value Pd, it is possible to detect abnormality of the out-side gate valves 31L and 31 by the PWM control.

(Operation in drive pattern S6)
FIG. 13 is a diagram illustrating a rear wheel side brake circuit in the drive pattern S6. In the drive pattern S6, the in valves 27L, R and the out valves 30L, R are opened, the other solenoid valves are closed, and the drive of the motor 19 is also stopped. That is, as a drive signal for the electromagnetic valve, a PWM control signal is output to the out-side gate valves 31L, R and closed, and an ON signal is output to the out valves 30L, R to open. When viewed from the drive pattern S5, the out-side gate valves 31L and R are closed, and only the hydraulic pressure is leaked from the out valves 30L and R.

  At this time, if both the hydraulic pressure sensors 29L and R are depressurized, it is determined that the out valves 30L and R are normal. On the other hand, when the pressure is not reduced, since the out valves 30L and R are not opened even when energized, the abnormality of the out valves 30L and R can be detected. That is, it is confirmed that the out valves 30L, R initially assumed for the first time after reaching the drive pattern S6 are correct.

  As described above, in the configuration of the first embodiment, the drive patterns S1 to S6 are executed when the ignition is turned on, so that the electromagnetic valves and liquids are driven before the vehicle travels regardless of the driver's brake operation. Abnormality detection of the pressure sensor can be performed. In addition, it is possible to specify in which configuration the abnormality has occurred, and after the abnormality has occurred, it is possible to quickly find the cause of the abnormality at a repair shop or the like, which is advantageous in terms of maintenance.

  Further, by detecting the abnormality with the isolation valve 24 closed, even if the pressure is increased by one motor 19, it is possible to verify the abnormality from the relative hydraulic pressure relationship between the left and right wheels, and the relationship with the temperature characteristics. Abnormality can be detected.

Further, technical ideas other than the claims that can be grasped from the above embodiments will be described below together with the effects thereof.
(A) In the brake control device according to claim 1,
An isolation valve is provided that divides the brake hydraulic pressure supplied from the hydraulic pressure generation source into a circuit configuration that can be supplied independently to the right wheel cylinder and the left wheel cylinder,
The brake control device according to claim 1, wherein the abnormality detecting means is means for detecting an abnormality of the hydraulic pressure sensor or the switching valve based on a relative relationship between hydraulic pressure states in the left and right circuit configurations.

  Therefore, an abnormality can be detected regardless of the temperature characteristics of the brake fluid pressure.

It is the schematic showing the structure of the brake control apparatus of Example 1. FIG. FIG. 3 is a schematic diagram illustrating a circuit configuration of a rear wheel hydraulic pressure control unit according to the first embodiment. 3 is a flowchart illustrating a main flow of abnormality detection processing according to the first embodiment. 3 is a flowchart illustrating drive pattern processing according to the first exemplary embodiment. 3 is a flowchart illustrating drive pattern processing according to the first exemplary embodiment. FIG. 3 is a diagram illustrating an operation combination of each component in each drive pattern of Example 1. 3 is a time chart illustrating drive pattern processing according to the first exemplary embodiment. FIG. 4 is a diagram illustrating a rear wheel brake circuit in drive pattern S1. FIG. 6 is a diagram showing a rear wheel side brake circuit in drive pattern S2. FIG. 5 is a diagram showing a rear wheel side brake circuit in drive pattern S3. FIG. 7 is a diagram showing a rear wheel side brake circuit in drive pattern S4. FIG. 6 is a diagram showing a rear wheel brake circuit in drive pattern S5. FIG. 7 is a diagram illustrating a rear wheel brake circuit in drive pattern S6.

Explanation of symbols

11, 12 In side gate valve 24 Isolation valve 27L, R In valve 30L, R Out valve 31L, R Out side gate valve 19 Motor

Claims (1)

A hydraulic pressure source for supplying brake hydraulic pressure to the wheel cylinder based on an output signal from the control unit;
A hydraulic pressure sensor for detecting the hydraulic pressure in the wheel cylinder;
A plurality of switching valves that switch oil passages in order to increase, hold, and reduce the hydraulic pressure in the wheel cylinder;
Pressure control means for switching the hydraulic pressure state in the wheel cylinder in a predetermined pattern consisting of a combination of increasing pressure, holding pressure and reducing pressure regardless of the operation of the brake pedal;
An abnormality detecting means for detecting an abnormality of the hydraulic pressure sensor or the switching valve based on whether or not a hydraulic pressure state corresponding to the predetermined pattern is obtained when the ignition is turned on;
A brake control device comprising:

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