JPH11180294A - Brake fluid pressure control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To specify a failure part generated in a system regarding a brake fluid pressure control device for controlling brake fluid pressure to optional fluid pressure in a vehicle. SOLUTION: A hydraulic circuit is provided to regulate wheel cylinder pressure PWC to specified fluid pressure. Feedback control for making the wheel cylinder pressure PWC coincide with target fluid pressure Pref is executed. During the execution of feedback control, a failure part is specified on the basis of the grade relation between the target fluid pressure Pref and wheel cylinder pressure PWC and deviation ΔP between the target fluid pressure Pref and wheel cylinder pressure PWC. Failure detecting accuracy can be improved by changing the failure judgment threshold value according to brake fluid temperature.

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, and more particularly to a brake fluid pressure control device suitable for controlling a brake fluid pressure to an arbitrary fluid pressure in a vehicle.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Laid-Open Publication No.
As disclosed in No. 8, a brake fluid pressure control device for controlling a brake fluid pressure in a vehicle is known. The conventional device includes a hydraulic pressure sensor that detects a master cylinder pressure,
And a hydraulic pressure sensor for detecting a wheel cylinder pressure.

The brake fluid pressure control device controls the wheel cylinder pressure so that a predetermined relationship is established between the master cylinder pressure and the wheel cylinder pressure. Therefore, when the master cylinder pressure and the wheel cylinder pressure do not satisfy the predetermined relationship, it can be determined that some failure has occurred in the brake fluid pressure control device. The above-mentioned conventional brake fluid pressure control device has a function of detecting a failure by such a method. For this reason, according to the above-mentioned conventional apparatus, a system failure can be reliably detected.

[0004]

However, the contents which can be detected by the above-mentioned conventional device are limited to the presence or absence of a failure. That is, depending on the above-described conventional apparatus, it is not possible to specify which part in the apparatus has a failure. When any failure occurs in the brake fluid pressure control device, it is desirable to be able to identify the location of the failure for effective fail-safe. In this regard, the above-described conventional apparatus is not always ideal for achieving effective fail-safe.

[0005] The present invention has been made in view of the above points, and an object of the present invention is to provide a brake fluid pressure control device capable of specifying a failure site occurring in a system.

[0006]

The above object is achieved by the present invention.
As described in the above, in a brake fluid pressure control device provided with a fluid pressure adjustment mechanism that regulates the wheel cylinder pressure to a predetermined fluid pressure, a control means for performing feedback control to match the wheel cylinder pressure to the target fluid pressure, Achieved by a brake fluid pressure control device including: a magnitude relationship between a target fluid pressure and the wheel cylinder pressure; and a failure location specifying unit that identifies a failure location based on a deviation between the target hydraulic pressure and the wheel cylinder pressure. Is done.

In the present invention, the wheel cylinder pressure is controlled so as to match the target hydraulic pressure. Therefore, when the system operates normally, the wheel cylinder pressure becomes a value close to the target hydraulic pressure. If a failure or a failure occurs in the system, a situation occurs in which the wheel cylinder pressure cannot be controlled to the target hydraulic pressure. At this time, a magnitude relationship and a deviation occur between the wheel cylinder pressure and the target hydraulic pressure according to the content of the failure. In the present invention, the failure site is specified based on the magnitude relationship and the deviation. .

According to a second aspect of the present invention, in the brake fluid pressure control device according to the first aspect, the fluid pressure adjusting mechanism includes a control valve, and the failure of the control valve is determined by the failure portion specifying means. A brake fluid pressure control device including a fail handling means for repeatedly opening and closing the control valve when detected is effective in eliminating a blockage of the control valve.

In the present invention, when a failure of the control valve provided in the hydraulic pressure adjusting mechanism is detected, the opening and closing operation of the control valve is repeated. The foreign matter that has caught in the control valve is separated from the control valve by repeating the opening and closing operation of the control valve. Therefore, according to the present invention, the control valve having the leakage failure can be returned to a normal state. Further, as set forth in claim 3, in the brake fluid pressure control device according to claim 1, a condition change in which the failure determination condition when the failure portion specifying means detects a failure is changed according to the temperature of the brake fluid. The brake fluid pressure control device including the means is effective in preventing erroneous detection of a failure caused by a change in the viscosity of the brake fluid.

[0010] In the present invention, the failure judging condition when the failure location specifying means detects a failure is changed according to the temperature of the brake fluid. When the temperature of the brake fluid changes, the relationship between the target hydraulic pressure and the wheel cylinder pressure also changes due to the change in the viscosity. Therefore, according to the present invention, erroneous detection of a failure is prevented by changing the failure determination condition according to the temperature of the brake fluid.

[0011]

FIG. 1 is a system configuration diagram of a brake fluid pressure control device according to an embodiment of the present invention. The brake fluid pressure control device of the present embodiment includes an electronic control unit 10 (hereinafter, referred to as ECU 10). The brake fluid pressure control device of the present embodiment includes a brake pedal 11. A brake switch 12 is provided near the brake pedal 11. The brake switch 12 outputs an ON signal when the brake pedal 11 is depressed. The ECU 10 determines whether or not the brake pedal 11 is depressed based on the output signal of the brake switch 12.

The brake pedal 11 is a brake booster 1
3 is connected. The brake booster 13 is fixed to the master cylinder 14. The brake booster 13 amplifies the brake depression force applied to the brake pedal 11 and transmits the same to the master cylinder 14. The master cylinder 14 generates a master cylinder pressure PMC having a predetermined boosting ratio with respect to the brake depression force.

The master cylinder 14 has a regulator 1
5 is fixed. A reservoir tank 16 is provided above the master cylinder 14 and the regulator 15. Brake fluid is stored in the reservoir tank 16. The master cylinder 14 becomes conductive with the reservoir tank 16 when the depression of the brake pedal 11 is released.

The brake fluid pressure control device has a pump 18. A reservoir tank 16 communicates with a suction hole of the pump 18. An accumulator 22 is connected to a discharge hole of the pump 18 via a check valve 20. The accumulator 22 accumulates the hydraulic pressure discharged from the pump 18 as an accumulator pressure P _ACC. The pump 18 controls the brake fluid in the reservoir tank 16 so that the accumulator pressure P _ACC falls within a predetermined range.
Discharge to two sides.

The accumulator 22 communicates with the regulator 15 described above. The regulator 15 uses the accumulator 22 as a high-pressure source and the reservoir tank 1
6 is used as a low pressure source to generate a hydraulic pressure equal to the master cylinder pressure PMC (hereinafter, referred to as a regulator pressure PREG). A fluid pressure passage 24 communicates with the regulator 15. The hydraulic pressure passage 24 has a brake hydraulic pressure sensor 26 (hereinafter, referred to as a hydraulic pressure sensor).
PREG sensor 26). PREG
The sensor 26 generates an output signal VREG according to the regulator pressure PREG. The ECU 10 outputs the output signal VREG.
The regulator pressure PREG is detected based on

In the hydraulic passage 24, a pressure increasing linear control valve 28 (hereinafter referred to as SLA 28) and a check valve 30
The hydraulic passage 31 communicates with the fluid passage 31 via the. SLA 28 is
The control valve opens when the hydraulic pressure in the hydraulic passage 24 is higher than a predetermined relief pressure Prel as compared with the hydraulic pressure in the hydraulic passage 31. The ECU 10 supplies a drive signal VSLA to the SLA 28. The SLA changes the effective diameter of the variable orifice to a value proportional to the drive signal VSLA. The check valve 30 is a one-way valve that allows a fluid to flow from the hydraulic passage 31 toward the hydraulic passage 24.

The hydraulic pressure passage 31 has a brake hydraulic pressure sensor 3
4 (hereinafter, referred to as a PRW sensor 34).
The PRW sensor 34 detects the hydraulic pressure PRW inside the hydraulic passage 31.
Generates an output signal VRW corresponding to. The ECU 10 detects the hydraulic pressure PRW based on the output signal VRW. The hydraulic passage 31 is provided with a pressure reducing linear control valve 36 (hereinafter, SLR).
36) and a pressure-restricting reservoir 40 via a check valve 38. The SLR 36 is a control valve having a variable orifice therein. The ECU 10
A drive signal VSLR is supplied to the SLR. SL
R36 determines the effective diameter of the variable orifice as the drive signal VSLR.
To a value proportional to. The check valve 38 is a one-way valve that allows a fluid to flow from the pressure reduction restriction reservoir 40 toward the hydraulic pressure passage 31. The decompression restriction reservoir 40 can store a predetermined amount of brake fluid therein.

A hydraulic passage 46 communicates with the hydraulic passage 31 via a holding valve 42 and a check valve 44. Holding valve 4
Reference numeral 2 denotes a two-position solenoid valve that keeps the valve open in a normal state and is closed when a drive signal is supplied from the ECU 10. On the other hand, the check valve 44 is a one-way valve that allows a fluid to flow from the hydraulic passage 46 to the hydraulic passage 31.

The hydraulic passage 46 communicates with the wheel cylinders 50 and 52 of the left and right rear wheels RL and RR via a P valve 48 and communicates with a reservoir passage 56 via a pressure reducing valve 54. The SRR 54 is a two-position solenoid valve that maintains a closed state in a normal state and is opened when a drive signal is supplied from the ECU 10. Reservoir passage 56
Communicates with the reservoir tank 16 described above.

The hydraulic pressure passage 31 is connected to a separation valve 58 (hereinafter, SS).
58) to the hydraulic passage 60. S
S58 is a two-position solenoid valve that keeps the valve closed in a normal state and is opened when a drive signal is supplied from the ECU 10. The hydraulic pressure passage 60 is provided with a brake hydraulic pressure sensor 62 (hereinafter, referred to as a PFW sensor 62). The PFW sensor 62 detects the hydraulic pressure PF in the hydraulic passage 60.
An output signal VFW corresponding to R is generated. ECU10
Detects the hydraulic pressure PFW based on the output signal VFW.

The hydraulic passage 60 communicates with a hydraulic passage 68 via a holding valve 64 and a check valve 66, and communicates with a hydraulic passage 74 via a holding valve 70 and a check valve 72. I have. Each of the holding valves 64 and 70 is a two-position solenoid valve that maintains an open state in a normal state and is closed when a drive signal is supplied from the ECU 10. On the other hand, the check valves 66 and 72 are one-way valves that allow only the flow of the fluid from the hydraulic passage 68 or the hydraulic passage 74 to the hydraulic passage 60.

The hydraulic passages 68 and 74 are respectively provided with wheel cylinders 76 and 78 of the left and right front wheels FL and FR.
And with the reservoir passage 56 via the pressure reducing valves 80 and 82. The pressure reducing valves 80 and 82 are two-position solenoid valves that maintain a closed state in a normal state and are opened when a drive signal is supplied from the ECU 10.

A hydraulic passage 84 communicates with the master cylinder 14. The hydraulic pressure passage 84 has a brake hydraulic pressure sensor 86
(Hereinafter, referred to as a PMC sensor 86). P
The MC sensor 86 generates an output signal VMC corresponding to the master cylinder pressure PMC. The ECU 10 outputs the output signal VM
The master cylinder pressure PMC is detected based on C. The hydraulic passage 84 also has a first master cut valve 88 (hereinafter, referred to as a first master cut valve 88).
Together with the liquid pressure passage 74 via the SMC _-1 referred to as 88) is communicated, the second master cut valve 90 (hereinafter, SMC _-2
90) is in communication with the hydraulic passage 68. S
The MC- ₁ 88 and the SMC- ₂ 90 are two-position solenoid valves that maintain a valve-open state in a normal state and are closed when a drive signal is supplied from the ECU 10.

The hydraulic pressure passage 84 further communicates with a brake stroke simulator 92. The brake stroke simulator 92 is composed of SMC _- 188 and SMC- _2.
When the valve 90 is closed, it is a mechanism for absorbing brake fluid flowing out of the master cylinder 14 and realizing an appropriate brake feeling. Next, the basic operation of the brake fluid pressure control device of the present embodiment will be described with reference to FIG.

FIG. 2 shows a flowchart of a main routine executed by the ECU 10. In the brake fluid pressure control device according to the present embodiment, the ECU 10 executes the main routine shown in FIG. 2 to generate a braking force corresponding to a brake operation. The routine shown in FIG. 2 is a routine that is repeatedly started each time the processing is completed. When the routine shown in FIG. 2 is started, first, the process of step 100 is executed.

In step 100, it is determined whether or not execution of the one-system hydraulic pressure control is permitted. One-system hydraulic pressure control is used when the brake hydraulic pressure control device functions normally.
This control is executed to generate a braking force corresponding to the brake operation. In the present embodiment, the execution of the one-system hydraulic pressure control is prohibited when a predetermined failure is found in the brake hydraulic pressure control device.

In this routine, if it is determined in step 100 that execution of the one-system hydraulic pressure control is not permitted, the process of step 102 is executed next. Meanwhile, 1
If it is determined that the execution of the system hydraulic pressure control is permitted, the process of step 104 is executed next. In step 102, a fail handling operation is performed. That is, this step 102 is executed when a predetermined failure has occurred in the brake fluid pressure control device. This step 10
In 2, in a situation where a predetermined failure has occurred in the brake fluid pressure control device, the most appropriate fail-response operation for generating the braking force intended by the driver is executed. When the process of step 102 ends, the current routine ends.

In step 104, it is determined whether or not a braking request has been made in the brake fluid pressure control device.
In this step 104, specifically, it is determined whether or not the brake pedal 11 is depressed based on the output signal VMC. As a result, when it is determined that the brake pedal 11 has not been depressed, it is determined that a braking request has not occurred. In this case, the process of step 106 is performed next.

In step 106, a process for bringing the brake fluid pressure control device into the normal state, that is, the state shown in FIG. 1 is executed. The normal state is realized by turning off all control valves of the brake fluid pressure control device. When the process of step 106 ends, the current routine ends. If it is determined in step 104 in this routine that a braking request has been issued to the brake fluid pressure control device, the process of step 108 is executed next.

In step 108, the master cylinder pressure PMC is detected based on the output signal VMC. In this embodiment, the master cylinder pressure PMC can be grasped as a value that substitutes the brake operation amount. Step 1
At 10, the target hydraulic pressure Pref is calculated based on the master cylinder pressure PMC. The target hydraulic pressure Pref is a hydraulic pressure to be supplied from the hydraulic pressure passages 31, 60 to the wheel cylinders 50, 52, 76, 78 in order to generate a braking force intended by the driver.

In step 112, the hydraulic pressure PRW of the hydraulic passage 31 and the hydraulic pressure PFW of the hydraulic passage 60 are detected.
In step 114, the wheel cylinder pressure PWC is calculated. Wheel cylinder pressure PWC is a representative value of the hydraulic pressure guided to wheel cylinders 50, 52, 76, 78 of all wheels. Wheel cylinder pressure PWC is calculated, for example, by averaging hydraulic pressure PRW and hydraulic pressure PFW.

In step 116, a deviation ΔP = Pref−PWC between the target hydraulic pressure Pref and the wheel cylinder pressure PWC is calculated. In step 118, the process of the SMC _-1 88 and SMC _-2 90 turned on (closed) is executed. In step 120, a process of turning SS58 on (valve open) is executed.

According to the processing of steps 118 and 120, the wheel cylinders 50, 5 of the left and right rear wheels RL, RR
2 to the hydraulic passage 31 and the left and right front wheels FL,
FR wheel cylinders 76 and 78 are connected to master cylinder 1
4 and can communicate with the hydraulic passage 31. According to the above state, the wheel cylinder pressures PWC of all the wheels can be controlled using the regulator 15 as a hydraulic pressure source.

In step 122, the SLA 28 and S
The cooperative control of the LR 36 is executed. SLA28 and S
According to the cooperative control of the LR 36, the SL is set such that the deviation ΔP between the target hydraulic pressure Pref and the wheel cylinder pressure PWC becomes small.
Drive voltages VSLA, V for A28 and SLR36
An SLR is provided. Specifically, when PWC is at a low pressure compared to Pref, SLC is set to increase the pressure of PWC.
A drive signal VSLA corresponding to the deviation ΔP is supplied to A28. When the PWC is higher than the Pref, the drive signal VSLA corresponding to the deviation ΔP is supplied to the SLR 36 in order to reduce the PWC. If the PWC is controlled near Pref, P
In order to maintain WC, drive voltages VSLA and VSL
R are both set to “0”.

According to the above cooperative control, when the brake fluid pressure control device functions normally, the wheel cylinder pressure P
WC can be accurately controlled near the target hydraulic pressure Pref. When the process of step 122 is completed, the current routine is completed. By the way, the brake fluid pressure control device according to the present embodiment performs wheel cylinder pressure PWC by one-system fluid pressure control when a failure occurs in the system.
May not be controlled properly. If such a failure occurs, if the failure site can be identified, it is necessary to determine the optimal fail-response operation for generating the braking force intended by the driver by minimizing the influence of the failure. Can be. Therefore, in the brake fluid pressure control device, it is important to specify a failed part.

The brake fluid pressure control device according to the present embodiment is characterized in that, in order to meet the above demand, the occurrence of a failure is detected and the processing for specifying the location of the detected failure is executed. doing. Hereinafter, the above-mentioned characteristic portions will be described with reference to FIGS. 3 to 5 show flowcharts of a control routine executed by the ECU 10 to realize the above functions. The routine shown in FIGS. 3 to 5 is a routine that is started each time the processing is completed. When the routine shown in FIGS. 3 to 5 is started, first, the process of step 124 is executed.

In step 124, PMC-PREG>
It is determined whether or not KP1 holds for a predetermined time KT1. The above condition is satisfied when the regulator pressure PREG is unduly low as compared with the master cylinder pressure PMC. In the brake fluid pressure control device of the present embodiment, when the system is normal, almost the regulator pressure PRE
G and the master cylinder pressure PMC are equal.

Therefore, when it is determined that the above condition is satisfied, a path (hereinafter, referred to as REG) including the regulator 15, the pump 18, the regulator 22, the hydraulic passage 24, and the like.
(Referred to as the hydraulic piping system).
If such a determination is made in step 124, the process of step 126 is executed next. Step 126
It is recognized that a failure has occurred in the REG hydraulic piping system. When the process of step 126 is executed, the EC
U10 thereafter executes an appropriate fail handling operation corresponding to the REG hydraulic piping system failure. When the process of step 126 ends, the current routine ends.

In this routine, the above step 124
If it is determined that the condition is not satisfied, the process of step 128 is executed next. In step 128, the PR
It is determined whether or not EG-PMC> KP2 is satisfied for a predetermined time KT2. The above condition is satisfied when the master cylinder pressure PMC is unduly low as compared with the regulator pressure PREG. Therefore, if it is determined that the above condition is satisfied, the master cylinder 14, the hydraulic passage 8
It can be determined that a failure has occurred in the path (hereinafter, referred to as the MC hydraulic piping system) including No. 4. If this determination is made in step 128, the process of step 130 is executed next.

In step 130, it is recognized that a failure has occurred in the MC hydraulic piping system. When the process of step 130 is executed, the ECU 10 thereafter executes an appropriate fail handling operation corresponding to the MC hydraulic piping system failure. When the process of step 130 ends, the current routine ends. In this routine, if it is determined that the condition of step 128 is not satisfied, then the process of step 132 is executed.

In step 132, | PREG-PRW
It is determined whether or not |> KP3 holds for a predetermined time KT3. Threshold value KP used in the above conditional expression
3 is a value substantially equal to the maximum value of the relief pressure Pref of the SLA 28. Therefore, when the SLA 28 functions normally, PREG-PRW> KP3 does not hold.

In the system of this embodiment, when the check valve 30 functions normally, PRW-PREG becomes K
Never exceed P3. Therefore, step 13
If it is determined in step 2 that the above condition is satisfied, the SLA
It can be determined that a failure has occurred in the check valve 28 or the check valve 30. In this case, the process of step 134 is executed next.

In step 134, it is recognized that the SLA 28 or the check valve 30 has a blockage.
When the process of step 134 is performed, the ECU 10
Performs an appropriate fail-response operation for a failure of the SLA 28 or the check valve 30 thereafter. When the process of step 134 ends, the current routine ends.

In this routine, step 132
If it is determined that the above condition is not satisfied, the process of step 136 shown in FIG. 4 is executed. Step 136
Then, it is determined whether or not a predetermined time α has elapsed after the one-system hydraulic pressure control is started in the brake hydraulic pressure control device. When the one-system hydraulic pressure control is started, the hydraulic pressure passage 60 provided with the PFW sensor 62 is brought into conduction with the hydraulic pressure passage 31 provided with the PRW sensor 34. Predetermined time α
When the system is normal, after the hydraulic passage 62 and the hydraulic passage 31 are brought into conduction, the hydraulic pressures PFR and PFR
This is the time required for the RW to become substantially equal pressure.

Therefore, if a large deviation occurs between the hydraulic pressure PFW and the hydraulic pressure PRW when it is determined in step 136 that the predetermined time α has elapsed, the system is not functioning properly. Can be determined. If it is determined in step 136 that the predetermined time α has elapsed after the one-system hydraulic pressure control is started in step 136, the process of step 138 is performed next.

In step 138, | PFW-PRW |
It is determined whether or not> KP4 holds for a predetermined time KT4. The above condition is satisfied when a large deviation occurs between the hydraulic pressure PFW and the hydraulic pressure PRW at the time when the predetermined time α has elapsed. In the system of the present embodiment,
Such a situation occurs when the SS 58 has a failure, and when the wheel cylinders 50, 52, 76, 78
Occurs when a failure occurs in any of the pipes communicating with the pipe.

Therefore, when it is determined that the above condition is satisfied, it can be determined that a leakage failure of SS58 or a leakage failure of the front wheel piping or the rear wheel piping has occurred.
If such a determination is made in step 138, the process of step 140 is performed next. Step 140
Then, it is recognized that a clogging failure of SS58 or a leakage failure of the front wheel system piping or the rear wheel system piping has occurred. When the process of step 140 is executed, the ECU 1
0 performs an appropriate fail-response operation corresponding to those failures thereafter. When the process of step 140 ends, the current routine ends.

In this routine, step 138 is performed.
If it is determined that the condition is not satisfied, the process of step 142 is executed next. In step 142, | P
It is determined whether REG-PFW |> KP5 holds for a predetermined time KT5. The threshold value KP5 used in the above conditional expression is substantially equal to the maximum value of the relief pressure Pref of the SLA 28. Therefore, when the system is normal, | PREG-PFW |> K at the time when a predetermined time α has elapsed after the one-system hydraulic pressure control is started.
P5 does not hold.

In the system according to the present embodiment, when a predetermined time α elapses after the one-system hydraulic pressure control is started, the PR
If EG-PFW> KP5 holds, it can be determined that the hydraulic pressure PFW is unduly low. Such a situation, S
This occurs when the LA 28 or SS 58 has a failure, and when the piping leading to the wheel cylinders 76, 78 of the front wheels has a failure.

In the system according to the present embodiment, if PFW-PREG> KP5 is satisfied when a predetermined time α has elapsed after the one-system hydraulic pressure control is started, the hydraulic pressure P
It can be determined that the FW is unduly high pressure. Such a situation occurs when the check valve 30 has a failure. Therefore, if it is determined in step 144 that the above condition is satisfied, it can be determined that the SLA 28, the check valve 30 or the SS 58, that is, a failure, or a front wheel system pipe leakage failure has occurred. In this case, the process of step 144 is performed next.

In step 144, it is recognized that a failure of the SLA 28, the check valve 30 or the SS 58, or a leakage failure of the front wheel system piping has occurred. When the process of step 144 is executed, the ECU 10
Perform an appropriate fail-response operation corresponding to those failures. When the process of step 144 ends, the current routine ends.

In this routine, the above-mentioned step 136 is executed.
When it is determined that the condition is not satisfied, and when it is determined that the condition of step 142 is not satisfied,
Next, the process of step 146 is performed. Step 14
6, PREG-PRW> KP6 and Pref-PW
It is determined whether the period in which at least one of C> KP7 is satisfied has continued for a predetermined time KT6. PREG-PR
When W> KP6 holds, it can be determined that the SLA 28 has a failure.

If it is determined that Pref-PWC> KP7 holds, it can be determined that PWC is improperly lower than the target hydraulic pressure Pref. PWC is SLA28
Alternatively, when an operation failure occurs in the SLR 36 or when a failure occurs in the front-wheel system piping or the rear-wheel system piping, the pressure becomes lower than the target hydraulic pressure Pref. Therefore, when the condition of step 146 is satisfied, it can be determined that an operation failure of the SLA 28 or SLR 36 or a leakage failure of the front wheel system piping or the rear wheel system piping has occurred. If such a determination is made in step 146, the process of step 148 is executed next.

At step 148, the SLA 28 or S
It is recognized that an operation failure of the LR 36 or a leakage failure of the front wheel system piping or the rear wheel system piping has occurred. When the process of step 148 is executed, the ECU 10 thereafter executes an appropriate fail handling operation corresponding to those failures. When the process of step 148 is completed, the current routine is completed.

In this routine, step 146 is performed.
If it is determined that the condition is not satisfied, the process of step 150 shown in FIG. 5 is executed next. Step 150
Then, it is determined whether or not the brake control with the feedback control of the wheel cylinder pressure PWC is being executed.
As a result, if it is determined that the brake control is not being executed, the current routine is terminated without any further processing. On the other hand, when it is determined that the brake control is being executed, the process of step 152 is executed next.

In step 152, it is determined whether or not all the following conditions are satisfied for a predetermined time KT7. VSLA> 0 VSLR = 0 Pref-PWC> KP8 The above conditions are for the target hydraulic pressure in a situation where a drive signal for requesting an increase in the wheel cylinder pressure PWC is supplied to the SLA 28 and SLR 36 without fail. This holds when the wheel cylinder pressure PWC is sufficiently low compared to Pref.

The threshold value KP8 used under the condition of step 152 is set to a value that is satisfied only when a large amount of brake fluid supplied from the SLA 28 to the hydraulic pressure passage 31 leaks out of one of the pipes. I have. Therefore, if it is determined in step 152 that the above conditions are continuously satisfied for the predetermined time KT7, it can be determined that a leakage failure has occurred in any of the pipes. If such a determination is made in step 152, the process of step 154 is performed next.

In step 154, it is recognized that a failure has occurred in either the front wheel system piping or the rear wheel system piping. When the process of step 154 is performed, the ECU
10 performs an appropriate fail-response operation corresponding to the failure thereafter. When the process of step 154 ends, the current routine ends. In this routine, if it is determined that the condition of step 152 is not satisfied, then the process of step 156 is executed.

At step 156, it is determined whether or not all the following conditions are satisfied for a predetermined time KT8. VSLA≥0 VSLR = 0 Pref-PWC> KP9 (<KP8) The above-mentioned conditions are those in which a drive signal is supplied to the SLA 28 and the SLR 36 to request that the wheel cylinder pressure PWC be reliably increased or held. This is established when the wheel cylinder pressure PWC is lower than the target hydraulic pressure Pref.

The threshold value KP9 used under the condition of the step 156 is set to a value that is satisfied only when the brake fluid supplied from the SLA 28 to the hydraulic pressure passage 31 leaks slightly. In the system of the present embodiment, such a situation occurs when a failure has occurred in the SLR 36. If such a situation is detected by the processing of step 156, the processing of step 158 is executed next.

At step 158, it is recognized that a failure has occurred in the SLR 36. When the process of step 158 is executed, the ECU 10 thereafter executes an appropriate fail handling operation corresponding to the failure. When the process of step 158 is completed, the current routine ends. If it is determined in this routine that the condition of step 156 is not satisfied, then step 160
Is performed.

In step 160, it is determined whether or not all the following conditions are satisfied for a predetermined time KT9. In the system of the present embodiment, the brake fluid that has flowed into the pressure-reducing reservoir 40 is supplied with the regulator pressure by releasing the brake pedal 11 in the system of the present embodiment. PREG
Is returned to the regulator 15 through the check valves 38 and 30. Therefore, the amount of the brake fluid stored in the decompression restriction reservoir 40 depends on the brake pedal 11.
After the brake pedal is depressed, it can be detected by accumulating the amount of brake fluid flowing through the SLR 36.

In the present embodiment, the ECU 10 detects the amount of the brake fluid flowing into the pressure-reducing reservoir 40 by the above method. Then, when the inflow amount has reached the capacity of the pressure reduction restriction reservoir 40, it is determined that the pressure reduction restriction reservoir 40 has reached the bottom state. Therefore, in step 160, it is determined that the above condition is satisfied when the amount of brake fluid that has flowed into the decompression restriction reservoir 40 has not reached the capacity of the decompression restriction reservoir 40.

When the pressure-reducing reservoir 40 is in the non-bottom state, the brake fluid in the wheel cylinder is set to S
It is possible to flow into the pressure reduction restriction reservoir 40 through the LR 36, that is, to reduce the wheel cylinder pressure PWC. Under the above conditions, the wheel cylinder pressure PWC is set to the target hydraulic pressure Pre under the above-described conditions, even though the SLA 28 and the SLR 36 are driven to reduce the pressure.
This holds when the pressure is sufficiently high compared to f.

In the system according to the present embodiment, such a situation occurs when a failure has occurred in the SLA 26 and the SM has failed.
This occurs when a failure has occurred in the C _- 188 or SMC _- 290, when a failure has occurred in the SLR 36, and when there is a sticking failure in the decompression restriction reservoir 40. If the occurrence of such a situation is recognized by the processing of step 160, the processing of step 162 is executed next.

[0066] At step 162, the leakage failure SLA26, leakage failure of SMC _-1 88 or SMC _-2 90, SL
It is recognized that either a failure of R36 or a fixation failure of the decompression restriction reservoir 40 has occurred. When the process of step 162 is performed, the ECU 10
Thereafter, an appropriate fail-response operation corresponding to those failures is executed. When the process of step 162 ends, the current routine ends.

In this routine, step 160
If it is determined that the condition is not satisfied, the process of step 164 is executed next. In step 164, it is determined whether or not all the following conditions are satisfied for a predetermined time KT10. VSLA = 0 VSLR ≧ 0 PWC-Pref> KP10 (<KP9) The above conditions are based on a situation in which a drive signal for requesting the SLA 28 and the SLR 36 to securely reduce or maintain the wheel cylinder pressure PWC is supplied. This holds when the wheel cylinder pressure PWC is higher than the target hydraulic pressure Pref.

[0068] threshold KP10 used in the condition of step 164, if slightly leakage SLA28 has occurred, and, established when the slightly leakage SMC _-1 88 or SMC _-2 90 occurs Is set to Therefore, if it is determined in step 164 that the condition is satisfied, the SLA 28 and the SMC _- 188 are determined.
Alternatively, it can be determined that the SMC _- 290 has a leakage failure that allows slight leakage of brake fluid. If such a determination is made in step 164, the process of step 166 is executed next. On the other hand, if such a determination is not made in step 164, the current routine is immediately terminated.

At step 166, SLA 28, SLA
It is recognized that a leak failure has occurred in either 28 or SMC-188 or SMC _{- 2} 90. This step 166
Is executed, the ECU 10 thereafter executes an appropriate fail handling operation corresponding to the failure. When the process of step 166 ends, the current routine ends.

As described above, according to the brake fluid pressure control device of the present embodiment, the failure of the fluid pressure circuit is detected by comparing the fluid pressure generated in each part of the fluid pressure circuit, and the detected failure is detected. Can be specified. In particular, according to the brake fluid pressure control device of the present embodiment, the wheel cylinder pressure P
By comparing the target hydraulic pressure Pref and the wheel cylinder pressure PWC during the execution of the brake control accompanied by the feedback control of the WC, it is possible to specify the location of various failures.

Further, the brake fluid pressure control device of the present embodiment specifies the detected failure portion, and then executes the most appropriate fail-response operation for the content of the failure. Therefore, according to the brake fluid pressure control device of the present embodiment, an excellent fail-safe function against a failure of the hydraulic circuit can be realized. Next, a failure handling operation executed by the brake fluid pressure control device of the present embodiment when detecting a failure in the SLR 36 will be described.

FIG. 6 shows a flowchart of a control routine executed by the ECU 10 to realize a failure handling operation for a failure of the SLR 36. The routine shown in FIG.
This is a routine that is repeatedly started each time the processing is completed. When the routine shown in FIG. 6 is started, first, the processing of step 170 is executed. In step 170, S
It is determined whether a failure of the LR 36 has been detected.
As a result, when it is determined that the failure of the SLR 36 has not been detected, the current routine is terminated without any further processing. On the other hand, if it is determined that the failure of the SLR 36 has been detected, then step 17 is executed.
2 is executed.

At step 172, the first refresh counter CREF1 is incremented. CREF1
Has been reset to "0" by the initial processing. CREF1 is a counter for counting the number of executions of the refresh processing of the SLR 36. Step 17
In 4, the count value of the CREF1 whether has reached a predetermined value n ₀ is determined. As a result, still CREF1 ≧ n ₀
If it is determined that is not established, then step 176
Is performed.

At step 176, a flag process for inhibiting execution of the regenerative cooperative control is performed. In an electric vehicle or a hybrid vehicle equipped with a motor as a drive source of a vehicle, when a driver applies a braking force, the motor is used as a generator to regenerate braking energy. At this time, the motor generates a regenerative braking force. The regenerative cooperative control is a control for adjusting the wheel cylinder pressure PWC of each wheel so that when the motor generates the regenerative braking force, the sum of the braking forces generated in the vehicle becomes the braking force intended by the driver. After the process of step 176 is performed, thereafter, execution of the regenerative cooperative control is prohibited.

At step 178, it is determined whether or not the vehicle is stopped. The process of step 178 is repeatedly executed until it is determined that the vehicle is stopped.
As a result, when it is determined that the vehicle is stopped, the process of step 180 is executed next. In step 180, the SLR 36 is refreshed. More specifically, a process of bringing the SLA 28 into a fully open state (a state in which the relief pressure Prel is the lowest) and a process of driving the SLR 36 at a duty, that is, a process of repeatedly opening and closing the SLR 36 are executed.

In step 182, the above-mentioned step 180 is executed.
After the start of the process, it is determined whether or not a predetermined time has elapsed. As a result, if it is determined that the predetermined time has not yet elapsed, the process of step 176 is executed again. On the other hand, if it is determined that the predetermined time has elapsed, the current routine ends. According to the above processing, if a failure of the SLR 36 is recognized, the SLR 36 is repeatedly opened and closed while the vehicle is stopped, with the SLA 28 fully opened, that is, with the regulator pressure PREG supplied to the SLR 36. be able to.
When the regulator pressure PREG is supplied, the SLR 36
When the opening / closing operation is repeated, the foreign matter that has been caught in the SLR 36 may fall off, and the SLR 36 may return to a normal state. For this reason, according to the brake fluid pressure control device of the present embodiment, it is possible to realize an excellent fail-safe function against a failure of the SLR 36.

In step 174 of this routine, the CR
If it is determined that EF1 ≧ n ₀ is satisfied, the SLR3 is executed regardless of the execution of the refresh processing a plurality of times.
6 can be determined not to return to a normal state.
In this case, the process of step 184 is executed next. At step 184, a flag process is performed to prohibit execution of the one-system hydraulic pressure control. When the process of step 184 is performed, it is determined that the execution of the one-system hydraulic pressure control is not permitted in step 100 shown in FIG.
As a result, the execution of the one-system hydraulic pressure control is prohibited.

At step 186, an alarm process for notifying the driver that a failure has occurred in the SLR 36 is executed. When the process of step 186 is performed, the current routine ends. According to the above processing, SL
When a failure that cannot be dealt with by the refresh processing occurs in R36, the state can be reliably recognized, and unnecessary refresh processing can be prevented.

In the above embodiment, the duty driving of the SLR 36 is terminated when a predetermined time has elapsed. However, the present invention is not limited to this, and the opening / closing operation is repeated a predetermined number of times. At this point, the duty driving of the SLR 36 may be terminated. Next, the brake fluid pressure control device of this embodiment
A failure handling operation executed when a failure of A28 is detected will be described.

FIG. 7 shows a flowchart of a control routine executed by the ECU 10 to realize a failure handling operation for a failure of the SLA 28. The routine shown in FIG.
This is a routine that is repeatedly started each time the processing is completed. When the routine shown in FIG. 7 is started, first, the process of step 190 is executed. In step 190, S
It is determined whether a failure of LA 28 has been detected.
As a result, if it is determined that the failure of the SLA 28 has not been detected, the current routine is terminated without any further processing. On the other hand, if it is determined that the failure of the SLA 28 has been detected, then step 19 is executed.
2 is executed.

At step 192, the second refresh counter CREF2 is incremented. CREF2
Has been reset to "0" by the initial processing. CREF2 is a counter for counting the number of times the SLA 28 has executed the refresh process. Step 19
In 4, the count value of CREF2 whether has reached a predetermined value n ₀ is determined. As a result, CREF2 ≧ n ₀
If it is determined that is not established, then step 196
Is performed.

At step 196, a flag process for inhibiting the execution of the regenerative cooperative control is performed. This step 1
After the processing of 96 is executed, the execution of the regenerative cooperative control is prohibited thereafter. In step 198, it is determined whether or not the output signal of the brake switch 12 has changed from the on state to the off state, that is, whether or not the depression of the brake pedal 11 has been released. The process of step 198 is repeatedly executed until it is determined that the above condition is satisfied. As a result, when it is determined that the output signal of the brake switch 12 has changed from the on state to the off state, the process of step 200 is executed next.

At step 200, the SLA 28 is refreshed. Specifically, a process of repeatedly opening and closing the SLA 28 at a predetermined duty ratio is executed. In step 202, it is determined whether or not a predetermined time has elapsed after the process of step 200 was started. As a result, if it is determined that the predetermined time has not yet elapsed, the process of step 200 is executed again. On the other hand, if it is determined that the predetermined time has elapsed, the current routine ends.

According to the above processing, when a failure of the SLA 28 is recognized, the SLA 28 can be repeatedly opened and closed in synchronization with the timing at which the depression of the brake pedal 11 is released. When the depression of the brake pedal 11 is released, from the wheel cylinder side or
The brake fluid flows backward from the pressure reduction restriction reservoir 40 toward the SLA 28. Therefore, under such circumstances SLA
When the opening / closing operation of the SLA 28 is repeated, the foreign matter that has been caught in the SLA 28 may fall off, and the SLA 28 may return to a normal state. For this reason, according to the brake fluid pressure control device of the present embodiment, it is possible to realize an excellent fail-safe function against a failure of the SLA 28.

In this routine, at step 194, the CR
If it is determined that EF2 ≧ n ₀ is satisfied, the SLA2 is executed regardless of the execution of the refresh processing a plurality of times.
8 can be determined not to return to a normal state.
In this case, the process of step 204 is performed next. In step 204, a flag process for prohibiting the execution of the one-system hydraulic pressure control is performed. When the process of step 204 is executed, it is determined that the execution of the one-system hydraulic pressure control is not permitted in step 100 shown in FIG.
As a result, the execution of the one-system hydraulic pressure control is prohibited.

At step 206, an alarm process for notifying the driver that a failure has occurred in the SLA 28 is executed. When the process of step 206 is performed, the current routine ends. According to the above processing, SL
When a failure that cannot be dealt with by the refresh processing occurs in A28, the state can be reliably recognized, and unnecessary refresh processing can be prevented.

In the above embodiment, the duty driving of the SLA 28 is terminated when a predetermined time has elapsed. However, the present invention is not limited to this, and the opening and closing operation is repeated a predetermined number of times. At this point, the duty driving of the SLA 28 may be terminated. Next, a second embodiment of the present invention will be described.

As described above, the brake fluid pressure control device of the first embodiment detects a failure in the fluid pressure circuit by comparing the fluid pressure generated in each part of the fluid pressure circuit. That is,
In the first embodiment, when the pressure difference that appears corresponding to a specific portion of the hydraulic circuit is larger than the pressure difference that should appear during normal operation, it is determined that a failure has occurred in that portion. However, the pressure difference generated in the hydraulic circuit increases as the viscosity of the brake fluid increases, that is, as the temperature of the brake fluid decreases.

For example, regarding the failure determination in step 124, the greater the viscosity of the brake fluid, the greater the differential pressure between the regulator pressure PREG and the master cylinder pressure PMC. Also, for example, in step 15
Regarding the failure determination in step 2, even if the SLA 28 normally performs the pressure increasing operation, as the viscosity of the brake fluid increases, a larger deviation appears between the target hydraulic pressure Pref and the wheel cylinder pressure PWC. For this reason, when the failure determination is performed at the extremely low temperature using the same threshold values KP1 and KP8 as those at the normal temperature, it is erroneously determined that the failure has occurred even though the REG hydraulic piping system and the SLA 28 are normal. A decision may be made. Therefore, the REG hydraulic piping system and the SLA
It is appropriate to increase the thresholds KP1 and KP8 in accordance with a decrease in the temperature of the brake fluid in order to improve the accuracy of the failure detection at 28. Similarly, for other parts of the hydraulic circuit, it is appropriate to increase the respective thresholds in accordance with a decrease in the temperature of the brake fluid in order to improve the failure detection accuracy.

The brake fluid pressure control device according to the present embodiment, in order to meet the above-mentioned demands, uses the system shown in FIG.
The CU 10 is realized by executing the routines shown in FIGS. 8 and 9 in addition to the routines shown in FIGS. In this embodiment, the ECU 10 is connected via a communication line to a regenerative ECU that executes the above-described regenerative cooperative control. The regenerative ECU is further connected to an engine ECU that controls the engine via a communication line. The engine ECU constantly monitors the temperature of the engine cooling water (hereinafter, referred to as engine water temperature TH), and according to the engine water temperature TH, two flags FENG1 and FEN.
Set the state of G2. That is, the flag FENG1
Is turned on when the engine water temperature TH is equal to or lower than a predetermined low temperature THL, and is turned off when TH exceeds THL. The flag FENG2 indicates the engine coolant temperature T
H is turned on when H is equal to or higher than a predetermined high temperature THH.
When H does not reach THH, it is turned off. The engine ECU determines these two flags FENG1 and FEN1
G2 is transmitted to the regenerative ECU. The regenerative ECU sets the flags FENG1 and FEN received from the engine ECU.
G2 is transferred to the ECU 10. The ECU 10 is a regenerative EC
The temperature state of the brake fluid is determined based on the on / off state of the flags FENG1 and FENG2 received from U.

Hereinafter, the contents of the routine shown in FIGS. 8 and 9 will be described. The routine shown in FIGS. 8 and 9 is a routine that is started each time the processing is completed. First, the routine shown in FIG. 8 will be described. FIG. 8 shows a flowchart of a routine executed by the ECU 10 to determine the temperature state of the brake fluid. When the routine shown in FIG. 8 is started, first, the process of step 300 is executed. In step 300, it is determined whether or not a predetermined time T1 has elapsed after the ignition switch was turned on. The ECU 10, the regenerative ECU, and the engine ECU execute an initial check process immediately after the ignition switch is turned on. The predetermined time T1 is
This time is set in consideration of the time required for the initial check process. If the predetermined time T1 or more has not elapsed after the ignition switch was turned on, the regenerative ECU or the engine ECU is performing the initial check. It is determined that there is a possibility. If such a determination is made in step 300, the flag FENG1
And FENG2 cannot be received, and therefore the flag FENG
It is determined that the temperature determination cannot be performed based on 1 and FENG2, and then the process of step 302 is executed. In step 302, the low temperature flag FLOW is set to the ON state. On the other hand, if the predetermined time T1 has elapsed in step 300, then step 304
Is performed.

In step 304, the ECU 10 and the regeneration E
It is determined whether the communication line connecting to the CU is normal. As a result, if the communication line is not normal, EC
U10 cannot receive the flags FENG1 and FENG2. In this case, the flags FENG1 and FEN
It is determined that the temperature determination based on G2 cannot be performed.
W is set to the ON state. On the other hand, if the communication line is normal in step 304, then in step 306
Is performed.

In step 306, it is determined whether or not the flags FENG1 and FENG2 are properly set. As described above, the flag FENG1 indicates the engine coolant temperature TH.
Is a flag that is turned on when the temperature is lower than THL. On the other hand, a flag FENG2 indicates that the engine coolant temperature TH
This flag is turned on when the temperature is higher than H. Therefore, the flags FENG1 and FENG2 cannot both be in the ON state as long as they are properly set. Therefore, in step 306, the flag FENG
If both 1 and FENG2 are on, it is determined that these flags are not set properly. In this case, it is determined that the temperature determination cannot be performed based on the flags FENG1 and FENG2, and then in step 302, the low temperature flag FLOW is set to the ON state. On the other hand, in step 306, the flag FEN
If G1 and FENG2 are properly set, the process of step 308 is executed next.

In step 308, it is determined whether or not the flag FENG1 is off. As a result, if not in the off state, the engine water temperature TH is equal to or lower than the predetermined low temperature THL. In this case, it is determined that the brake fluid is very likely to be in an extremely low temperature state, and then in step 302, the low temperature flag FLOW is set to the ON state. On the other hand, if the flag FENG1 is off in step 308, it is determined that the brake fluid is in the normal temperature state. In this case, in step 310, the low temperature flag FLOW is reset to the off state. When the process of step 310 ends, the current routine ends.

Step 312 following the above step 302
Then, it is determined whether or not the low temperature flag FLOW is maintained in the on state for a predetermined time T2 or more. As a result, if an affirmative determination is made, it is determined that the brake fluid has been heated to the normal temperature state by the operation of the hydraulic circuit for the predetermined time T2 or more. In this case, in step 310, the low temperature flag FLOW is reset to the off state. On the other hand, if a negative determination is made in step 312, the process of step 314 is executed next.

In step 314, it is determined whether or not the flag FENG2 has been set to the ON state a predetermined time T3 or more before the present time. As a result, if an affirmative determination is made, it means that the brake fluid pressure control device has been operating continuously for at least the predetermined time T3 after the engine coolant temperature TH has become equal to or higher than the predetermined high temperature THH.
In this case, it is determined that the temperature of the brake fluid has been raised to the normal temperature state by the operation of the hydraulic circuit during that time, and then in step 310, the low temperature flag FLOW is reset to the off state. On the other hand, if a negative determination is made in step 314, the current routine ends while the low temperature flag FLOW is maintained in the on state.

According to the processing in steps 312 and 314, the temperature state of the brake fluid can be determined in consideration of not only the engine coolant temperature TH but also the temperature increase of the brake fluid accompanying the operation of the hydraulic circuit. . Therefore, according to the routine shown in FIG. 8, the temperature state of the brake fluid can be more accurately determined. In the above routine, the flag FEN is set in step 308.
Not only when G1 is on, but also in step 30
If a negative determination is made in 0, 304, or 306, that is, if the temperature determination based on the flags FENG1 and FENG2 cannot be performed, the low temperature flag FLOW is set to the ON state in step 302. As described later, when the low temperature flag FLOW is in the ON state, the threshold values KP1 to KP11 for performing the failure determination are determined.
Is set to a larger value than when the low temperature flag FLOW is in the off state. In the routine shown in FIG. 3 to FIG. 5, since a failure is detected when the predetermined pressure difference exceeds the threshold values KP1 to KP11, the threshold values KP1 to KP
If 11 is set to a large value, it becomes difficult to detect a failure. Therefore, according to the routine shown in FIG. 8, when the temperature determination based on the flags FENG1 and FENG2 cannot be performed, the low-temperature flag FLOW is set to the ON state. It has become difficult.

Next, the routine shown in FIG. 9 will be described. FIG. 9 shows a flowchart of a routine executed by the ECU 10 to correct the values of the threshold values KP1 to KP11 according to the temperature state of the brake fluid. When the routine shown in FIG. 9 is started, first, the process of step 350 is executed. In step 350, it is determined whether the low temperature flag FLOW is in an off state. As a result, if the low temperature flag FLOW is in the off state, that is, if the brake fluid is in the normal temperature state, the process of step 352 is executed next. On the other hand, if the low temperature flag FLOW is in the on state in step 350, that is, if the brake fluid is in the extremely low temperature state, the process of step 354 is executed next.

At step 352, the threshold value KPi (i
= 1 to 11) is substituted for the predetermined value CPi. The predetermined value CPi is a value corresponding to the threshold value KPi when the brake fluid is in a normal temperature state. When the process of step 352 ends, the current routine ends. In step 354, the threshold value KPi is set to (CPi +
αi) (αi> 0) is substituted. As described above, when the brake fluid is in a very low temperature state, the pressure difference appearing at each part of the hydraulic circuit increases due to the increase in viscosity as compared with the normal temperature. αi is a correction value set corresponding to each part of the hydraulic circuit in consideration of the rise in the differential pressure in the extremely low temperature state. When the process of step 354 ends, the current routine ends.

As described above, according to the routine shown in FIG. 8, the temperature state of the brake fluid can be accurately determined. According to the routine shown in FIG. 9, the threshold values KP1 to KP
By changing the value of 11, the failure determination condition of each part in the routine shown in FIGS. 3 to 5 can be corrected to an appropriate condition according to the change in the viscosity of the brake fluid. Therefore, according to the brake fluid pressure control device of the present embodiment, erroneous detection due to a change in the temperature of the brake fluid can be prevented, and the accuracy of failure detection can be improved. Further, by preventing the erroneous detection of the failure, it is possible to prevent the failure handling operation from being executed improperly based on the erroneous failure detection in the routine shown in FIGS.

In the second embodiment, the threshold value KP
Although only 1 to KT11 are changed according to the temperature of the brake fluid, the present invention is not limited to this, and the determination values KT1 to KT10 relating to time are changed according to the temperature of the brake fluid. Is also good.
That is, when a pressure difference is temporarily generated between two pressures that should be equal pressures, the longer the viscosity of the brake fluid, the longer it takes to eliminate the pressure difference. Therefore, KT1 to KT10 in the extremely low temperature state
With the threshold values KP1 to KP11, or
The failure detection accuracy can be improved by setting the value alone to be larger than the value in the normal temperature state.

In the second embodiment, the threshold value KP
1 to KP11 are changed in two steps corresponding to the normal temperature state and the extremely low temperature state, but the present invention is not limited to this, and may be changed to three or more steps in accordance with the temperature of the brake fluid. It may be. Further, in the second embodiment, the temperature state of the brake fluid is determined based on the engine coolant temperature TH. However, the present invention is not limited to this, and a temperature sensor is provided in the hydraulic circuit itself or in the vicinity thereof, and the temperature of the brake fluid is determined. May be detected more directly.

In the first and second embodiments, the hydraulic circuit of the brake fluid pressure control device is described in the "hydraulic pressure adjusting mechanism", and the SLA 28 and SLR 36 are described in the claim. The ECU 10 executes feedback control so as to make the wheel cylinder pressure PWC equal to the target hydraulic pressure Pref. By executing the processing of step 166, the “failure part specifying means” described in the claims is executed. By executing the processing of steps 170 to 182 and 190 to 202, the “failure responding means” described in the claims is executed.
By executing the routine shown in FIG. 9, the "condition changing means" described in the claims is realized.

[0104]

As described above, according to the first aspect of the present invention, the failure site of the system is specified based on the magnitude relationship and the deviation between the wheel cylinder pressure and the target hydraulic pressure. be able to. According to the second aspect of the invention, when a failure occurs in the on-off valve,
The failure can be detected and the on-off valve can be returned to a normal state.

Further, according to the third aspect of the invention, it is possible to prevent erroneous detection of a failure due to a change in the temperature of the brake fluid.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a brake fluid pressure control device according to an embodiment of the present invention.

FIG. 2 is a flowchart of a main routine executed in the brake fluid pressure control device shown in FIG.

FIG. 3 is a flowchart (part 1) of a control routine executed to detect a failure and specify a failure site in the brake fluid pressure control device shown in FIG. 1;

FIG. 4 is a flowchart (part 2) of a control routine executed to detect a failure and specify a failure site in the brake fluid pressure control device shown in FIG. 1;

FIG. 5 is a flowchart (part 3) of a control routine executed to detect a failure and specify a failure site in the brake fluid pressure control device shown in FIG. 1;

FIG. 6 shows a brake fluid pressure control system in the brake fluid pressure control device shown in FIG.
9 is a flowchart of a control routine that is executed to realize a failure handling operation for a failure of R.

FIG. 7 is a block diagram of the brake fluid pressure control device shown in FIG.
9 is a flowchart of a control routine that is executed to realize a failure handling operation for failure of A.

FIG. 8 is a flowchart of a control routine executed to determine a temperature state of brake fluid in a second embodiment of the present invention.

FIG. 9 is a flowchart of a control routine executed to change a threshold value for failure determination according to a brake fluid temperature state in a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 electronic control unit (ECU) 26 hydraulic pressure sensor (PREG sensor) 28 pressure increasing linear control valve (SLA) 36 pressure reducing linear control valve (SLR) 40 pressure reducing restriction reservoir 58 separation valve (SS) 62 liquid pressure sensor (PFW sensor) ) 86 Fluid pressure sensor (PMC sensor) PREG Regulator pressure PFW Front wheel wheel cylinder pressure PMC master cylinder pressure

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaki Hoshino 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation

Claims (3)

[Claims] 1. A brake fluid pressure control device having a fluid pressure adjusting mechanism for regulating a wheel cylinder pressure to a predetermined fluid pressure, a control means for performing feedback control for making the wheel cylinder pressure equal to a target fluid pressure, A brake fluid, comprising: a magnitude relationship between a target hydraulic pressure and the wheel cylinder pressure, and a failure site identification unit that identifies a failure site based on a deviation between the target hydraulic pressure and the wheel cylinder pressure. Pressure control device. 2. The brake hydraulic pressure control device according to claim 1, wherein the hydraulic pressure adjustment mechanism includes a control valve, and the control valve is provided when a failure of the control valve is detected by the failure location specifying unit. A brake fluid pressure control device comprising a failure handling means for repeatedly performing opening and closing operations. 3. The brake fluid pressure control device according to claim 1, further comprising a condition changing unit that changes a failure determination condition when the failure site specifying unit detects a failure in accordance with a temperature of brake fluid. Features a brake fluid pressure control device.