JP3684882B2 - Brake hydraulic pressure control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a brake fluid pressure control device that controls a brake fluid pressure by controlling a brake fluid pressure.
[0002]
[Prior art]
Conventionally, as a brake fluid pressure control device that controls the brake fluid pressure by controlling the brake fluid pressure, there is a device disclosed in Japanese Patent Laid-Open No. 10-1000088. In this brake fluid pressure control device, a failure state such as a sensor failure or a system piping failure is determined and braking control is performed in accordance with the failure state.
[0003]
[Problems to be solved by the invention]
However, in the above-described brake fluid pressure control device, no countermeasures are taken for the case where a failed wheel is generated due to the fluid leakage of the wheel cylinder (W / C). However, there is a problem that the braking performance is reduced due to the necessity of brake control by only one system not including the lost wheel.
[0004]
An object of the present invention is to provide a brake fluid pressure control device capable of suppressing a decrease in braking performance even when a failed wheel is generated due to a fluid leakage of a wheel cylinder.
[0005]
[Means for Solving the Problems]
The brake hydraulic pressure control device according to claim 1 includes a control device that causes a hydraulic pressure source to communicate with a wheel cylinder in each of a plurality of wheels and controls a hydraulic pressure of the wheel cylinder during a brake operation. In the above, when the difference between the hydraulic pressure of the wheel cylinder at one wheel and the hydraulic pressure of the wheel cylinder at the other wheel is equal to or greater than a predetermined value, the failure determination is performed to detect the wheel failure. The detecting means has a hydraulic pressure in the wheel cylinder in one wheel in a state in which a holding valve provided corresponding to the wheel cylinder of each wheel is closed, and a wheel in the other wheel. The absolute value of the difference from the hydraulic pressure in the cylinder is greater than the predetermined value, and the rate of change of the wheel cylinder with the lower hydraulic pressure in the wheel is less than the predetermined negative When a small, performs second fail criterion for detecting a failure of the wheel, the controller, the malfunction by detecting means to cut off the hydraulic pressure supply from the hydraulic pressure source to the detected wheel wheel cylinder In addition, the hydraulic pressure of the wheel cylinder in the wheels other than the wheel in which the failure is detected is controlled.
[0006]
The brake hydraulic pressure control device according to claim 2, wherein the control device obtains a hydraulic gain of a normal wheel adjacent to the wheel in which the failure is detected and a second normal wheel located on a diagonal line of the normal wheel. Based on the hydraulic gains of the normal wheel and the second normal wheel, the hydraulic gain of the third normal wheel located on the diagonal line of the wheel where the failure is detected is calculated.
[0007]
The brake hydraulic pressure control device according to claim 3 includes a control device that allows a hydraulic pressure source to communicate with a wheel cylinder in each of a plurality of wheels and controls a hydraulic pressure of the wheel cylinder during a brake operation. In the above, when the difference between the hydraulic pressure of the wheel cylinder at one wheel and the hydraulic pressure of the wheel cylinder at the other wheel is equal to or greater than a predetermined value, the failure determination is performed to detect the wheel failure. has a detection means, each wheel are arranged on the left and right front and rear, with the control device, the malfunction by detecting means to cut off the hydraulic pressure supply from the hydraulic pressure source to the detected wheel wheel cylinder, failure is used to control the hydraulic pressure of the wheel cylinder at the wheels other than the detected wheel controller, the normal wheel next to the wheel failure is detected Oyo Determine the hydraulic gain of the second normal wheel located on the diagonal of the normal wheel, and locate it on the diagonal of the wheel where the fault was detected based on the hydraulic gain of the normal wheel and the second normal wheel And calculating a hydraulic gain of a third normal wheel .
[0008]
The brake hydraulic pressure control device according to claim 4 includes a control device that causes a hydraulic pressure source to communicate with a wheel cylinder in each of a plurality of wheels and controls a hydraulic pressure of the wheel cylinder during a brake operation. In the above, when the difference between the hydraulic pressure of the wheel cylinder at one wheel and the hydraulic pressure of the wheel cylinder at the other wheel is equal to or greater than a predetermined value, the failure determination is performed to detect the wheel failure. The control device has a detection unit, and the control device cuts off the hydraulic pressure supply from the hydraulic pressure source to the wheel cylinder of the wheel in which the failure is detected by the detection unit, and the wheels in the wheels other than the wheel in which the failure is detected. Controls the hydraulic pressure of the cylinder. The detection means is requesting braking control by depressing the brake pedal and the amount of brake pedal operation. The normal control in which the target control amount of the fluid pressure in the wheel cylinder is calculated on the basis, and performs failure determination.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a hydraulic brake circuit diagram of an electronically controlled brake device 10 according to the first embodiment. This electronically controlled brake device 10 has a master cylinder 14 that pumps hydraulic oil in response to a driver's depressing operation of a brake pedal 12.
[0013]
A stroke simulator 18 is connected to the master cylinder 14 via a normally open type simulator cut valve 16. Master pressure sensors 24 and 26 for detecting the pressure in the master cylinder 14 are provided between the master cylinder 14 and the normally closed master cut valves 20 and 22.
[0014]
One end of a hydraulic supply conduit 30 and a hydraulic discharge conduit 32 is connected to the reservoir 28. A pump 36 driven by a motor 34 is provided in the middle of the hydraulic supply conduit 30, and an accumulator 38 that stores hydraulic pressure increased by rotating the pump 36 is provided. An accumulator pressure sensor 40 for detecting the internal pressure of the accumulator 38 is provided in the middle of the hydraulic pressure supply conduit 30. Further, a relief valve 44 is provided between the hydraulic supply conduit 30 and the hydraulic discharge conduit 32 to return the hydraulic oil to the reservoir 28 when the pressure in the hydraulic supply conduit 30 becomes high.
[0015]
The other end of the hydraulic pressure supply conduit 30 is connected to a left front wheel wheel cylinder 48FL via a left front wheel hydraulic pressure supply conduit 46FL, and is connected to a right front wheel wheel cylinder 48FR via a right front wheel hydraulic pressure supply conduit 46FR. Yes. The other end of the hydraulic pressure supply conduit 30 is connected to the left rear wheel wheel cylinder 48RL via the left rear wheel hydraulic pressure supply conduit 46RL, and the right rear wheel wheel is connected to the right rear wheel hydraulic pressure supply conduit 46RR. It is connected to the cylinder 48RR.
[0016]
Similarly, the other end of the hydraulic discharge conduit 32 is connected to the left front wheel wheel cylinder 48FL via the left front wheel hydraulic discharge conduit 50FL, and is connected to the right front wheel wheel cylinder 48FR via the right front wheel hydraulic discharge conduit 50FR. Has been. The other end of the hydraulic discharge conduit 32 is connected to the left rear wheel wheel cylinder 48RL via the left rear wheel hydraulic discharge conduit 50RL, and the right rear wheel via the right rear wheel hydraulic discharge conduit 50RR. It is connected to the cylinder 48RR.
[0017]
Electromagnetic flow control valves (holding valves) 52FL, 52FR, 52RL, and 52RR are provided in the middle of the hydraulic supply conduits 46FL, 46FR, 46RL, and 46RR, respectively. Electromagnetic flow control valves (pressure reducing valves) 54FL, 54FR, 54RL, and 54RR are provided, respectively. In addition, pressure sensors 56FL, 56FR, 56RL and 56RR are provided to detect the respective pressures in the wheel cylinders 48FL, 48FR, 48RL and 48RR. Further, a normally closed electromagnetic flow control valve 58 is provided between the wheel cylinders 48FL and 48FR, and a normally closed electromagnetic flow control valve 60 is provided between the wheel cylinders 48RL and 48RR. .
[0018]
The ECU (not shown) includes a signal indicating the pressure in the master cylinder 14 output from the master pressure sensors 24 and 26, a signal indicating the pressure in the accumulator 38 output from the accumulator pressure sensor 40, and pressure sensors 56FL to 56RR. A signal indicating the pressure in the wheel cylinders 48FL to 48RR is output. On the other hand, control signals are output to the simulator cut valve 16, the master cut valves 20 and 22, the electromagnetic flow control valves 52 FL to 52 RR, 54 FL to 54 RR, 58 and 60, and the motor 34.
[0019]
When the brake pedal 12 is operated during the normal control, the electronically controlled brake device 10 detects the pressure in the master cylinder 14 by the master pressure sensors 24 and 26, and detects by the master pressure sensors 24 and 26. The target control amount is calculated based on the pressure in the master cylinder 14 thus obtained. Then, the braking force applied to each wheel is controlled by controlling the pressure (working hydraulic pressure) in the wheel cylinders 48FL to 48RR based on the target control amount.
[0020]
In addition, the electronically controlled brake device 10 performs brake control for three wheels excluding the failed wheel by determining the failed wheel in the ECU. That is, as shown in the flowchart of FIG. 2, it is first determined whether or not the failure determination 1 or the failure determination 2 is established (step S10).
[0021]
Here, the failure determination 1 is performed when there is a relatively large amount of hydraulic oil leakage, and is performed according to the flowchart of FIG. That is, it is determined that the brake is being requested by depressing the brake pedal 12, and that the anti-lock brake system (ABS) and the vehicle behavior control system (VSC) by the brake control are not being controlled (step S20). If it is determined that the condition of step S20 is satisfied, the pressure (P _{W / C} FR) in the wheel cylinder 48FR detected by the pressure sensor 56FR and the pressure in the wheel cylinder 48FL detected by the pressure sensor 56FL are determined. The absolute value of the difference from the pressure (P _{W / C} FL) is larger than the predetermined value (P _diff1 ), and P _{W / C} FR or P _{W / C} FL (P _{W / C} F *) and the wheel cylinder When the absolute value of the difference from the target value (P _{W / C} target) is greater than a predetermined value (P _diff2 ) and the pressure sensors 56FR and 56FL are not abnormal (step S21) ), It is determined that failure determination 1 is established (step S22).
[0022]
It should be _noted that P _{W / C} FR for the right front wheel and P _{W / for the} left front wheel are determined by determining whether or not the absolute value of the difference between P _{W / C} F * and the P _{W / C} target is larger than P _{diff2. It} is possible to determine which of the CFL is faulty. In addition, by performing the process of step S21 for the pressures P _{W / C} RR and P _{W / C} RL in the wheel cylinders of the left and right rear wheels, the faulty wheel is specified when the left and right rear wheels have a fault. Can do.
[0023]
Further, the failure determination 2 is a determination when the hydraulic oil leakage is small, and is performed according to the flowchart of FIG. That is, it is determined whether the estimated vehicle speed (VSo) is 0 (step S30). If it is determined here that VSo = 0, it is determined whether or not the stop switch ON or the pressure ( _PMC ) in the master cylinder 14 is greater than a predetermined threshold (A) (step S31). . Here P _MC> If it is determined that A is in a braking required vehicle rate of change per unit time of the P _MC it is determined that the state in which the stop is a predetermined threshold value (B) It is determined whether it is smaller than (step S32).
[0024]
Here dP _MC / dt <If it is determined that the B is holding valves provided corresponding to the holding valve 52FL and the right front wheel of the wheel cylinder 48FR is provided corresponding to the left front wheel cylinder 48FL A closing signal is output for a certain time to 52FR (step S33). Next, the absolute value of the difference between the pressure in the wheel cylinder 48FR (P _{W / C} FR) and the pressure in the wheel cylinder 48FL (P _{W / C} FL) when the holding valves 52FL and 52FR are closed is a predetermined value. The rate of change of P _{W / C} FR or P _{W / C} FL which is larger than the value (P _diff3 ) and lower in pressure (P _{W / C} F *) is a predetermined negative value (−ΔP ) (Step S34), the failure determination value is counted up (step S35), assuming that there is a failure in P _{W / C} F *.
[0025]
Next, it is determined whether or not the failure determination value is greater than or equal to a predetermined value (step S36). That is, by repeatedly performing the processing from step S30 to step S36, it is determined that the failure determination 2 is established when the failure determination value is equal to or greater than a predetermined value (step S37).
[0026]
The failure ring is identified by judging which pressure is lower in P _{W / C} FR and P _{W / C} FL. In addition, the same processing is performed on the pressures P _{W / C} RR and P _{W / C} RL in the wheel cylinders of the left and right rear wheels, so that when the left and right rear wheels have a failure, the failure determination 2 is performed and the pressure is lost. You can identify the fallen circle.
[0027]
When the failure determination 1 or the failure determination 2 is established in the processing of the above-described step S10 and the failure wheel can be identified, the failure wheel holding valve is closed, and the brake is performed by the three wheels excluding the failure wheel. Control is performed (step S11), and the warning lamp is turned on (step S12).
[0028]
If it is determined in step S10 that neither failure determination 1 nor failure determination 2 has been established, the open failure determination of the holding valves 52FL to 52RR and the pressure sensors 56FL to 56RR are performed. An abnormality determination is made, and when it is determined that the holding valves 52FL to 52RR are in an open failure and when it is determined that the pressure sensors 56FL to 56RR are abnormal (step S13), the warning lamp is turned on (step S13). S12).
[0029]
On the other hand, when it is determined that the holding valves 52FL to 52RR are not open and the pressure sensors 56FL to 56RR are normal (step S13), brake control by four wheels, that is, normal control is performed. Continue (step S14). The determination of the open failure of the holding valves 52FL to 52RR is made according to the flowchart shown in FIG. Here, steps S40 to S43 in this flowchart are the same as steps S30 to S33 in the flowchart shown in FIG.
[0030]
When the output of the control signal for closing the holding valves 52FL to 52RR is completed (step S43), the control signal for opening the pressure reducing valves 54FL to 54RR is output (step S44). When the internal pressure (P _{W / C} F *) of any of the wheel cylinders 48FL to 48RR decreases (step S45), the holding valve provided corresponding to the wheel cylinder whose internal pressure has decreased is open. It is determined that it is in progress (step S46). On the other hand, when there is no decrease in the internal pressure (P _{W / C} F *) in any of the wheel cylinders 48FL to 48RR (step S45), a control signal for closing the pressure reducing valves 54FL to 54RR is output (step S48). ). Here, when the internal pressure (P _{W / C} F *) of any of the wheel cylinders 48FL to 48RR changes (step S48), the holding valve provided corresponding to the wheel cylinder whose internal pressure has changed is open failure. It is determined that it is in progress (step S46). If any of the internal pressures (P _{W / C} F *) of the wheel cylinders 48FL to 48RR does not change (step S48), a control signal for opening the holding valve is output (step S47), and the holding valve opens. The determination ends.
[0031]
According to the first embodiment, when a faulty wheel is generated due to a failure due to leakage of hydraulic oil from the wheel cylinder, the three wheels other than the faulty wheel are subject to brake control. A sufficient braking force can be obtained even when a depression occurs.
[0032]
Next, a second embodiment of the present invention will be described. The electronically controlled brake device 10 according to the second embodiment has the same configuration as the electronically controlled brake device according to the first embodiment (see FIG. 1).
[0033]
In this electronically controlled brake device, as shown in FIG. 6, first, a failure determination 1 (see FIG. 3 in the first embodiment) or a failure determination 2 (see FIG. 4 in the first embodiment) is performed. It is determined whether or not it is established (step S50). If it is determined that the failure determination 1 or the failure determination 2 has been established, the current vehicle speed (VSo) that is estimated is estimated.
Is determined to be greater than a predetermined speed (VSo _min ) (step S51). That is, only if VSo> VSo _min, performs brake control shown in this flow chart.
[0034]
Next, the normal front wheel hydraulic gain (FrGain) is obtained according to the equation shown in step S52, and the normal rear wheel hydraulic gain (ReGain) located on the diagonal of the normal front wheel according to the equation shown in step S53. Further, according to the equation shown in step S54, the hydraulic gain (abnormal system gain) of the normal wheel located on the diagonal line of the failed wheel is determined. Here, VSo _max is the maximum value of the vehicle speed, and the Fr distribution coefficient and the Re distribution coefficient are coefficients having a relationship of Fr distribution coefficient + Re distribution coefficient = 1. Next, on the basis of FrGain, ReGain, and abnormal system Gain, brake control is performed on three wheels other than the failed wheel as in the electronically controlled brake device according to the first embodiment (step S55).
[0035]
According to the electronically controlled brake device according to the second embodiment, when the vehicle speed increases, the hydraulic gain of the normal front wheel (FrGain) and the hydraulic gain of the normal rear wheel (ReGain) positioned on the diagonal line of the normal front wheel are increased. Increases, and the hydraulic gain (abnormal system gain) of the normal wheel located on the diagonal line of the failed wheel decreases. Therefore, the stability of the vehicle can be maintained even when a missing wheel is generated and brake control is performed using three wheels.
[0036]
【The invention's effect】
According to the present invention, since all the wheels other than the failed wheel are subjected to the brake control, a sufficient braking force can be obtained even when the wheel has failed.
[0037]
In addition, when changing the hydraulic pressure distribution of the wheel cylinders of other wheels according to the position of the wheel where the failure is detected, the vehicle changes the braking force distribution to the remaining wheels depending on the position of the failed wheel. Stability can be maintained.
[Brief description of the drawings]
FIG. 1 is a hydraulic brake circuit diagram of an electronically controlled brake device according to a first embodiment.
FIG. 2 is a flowchart for explaining brake control in the electronically controlled brake device according to the first embodiment;
FIG. 3 is a flowchart for explaining failure determination 1 in the electronically controlled brake device according to the first embodiment;
FIG. 4 is a flowchart for explaining failure determination 2 in the electronically controlled brake device according to the first embodiment.
FIG. 5 is a flowchart for determining an open failure of the holding valve in the electronically controlled brake device according to the first embodiment.
FIG. 6 is a flowchart for explaining brake control in the electronically controlled brake device according to the second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Electronically controlled brake device, 12 ... Brake pedal, 14 ... Master cylinder, 16 ... Simulator cut valve, 18 ... Stroke simulator, 20, 22 ... Master cut valve, 24, 26 ... Master pressure sensor, 28 ... Reservoir, 30 ... Hydraulic supply conduit, 32 ... hydraulic discharge conduit, 34 ... motor, 36 ... pump, 38 ... accumulator, 48FL-48RR ... wheel cylinder, 52FL-52RR, 54FL-54RR ... electromagnetic flow control valve.

Claims (4)

In the brake fluid pressure control device having a control device for communicating the fluid pressure source and the wheel cylinder in each of the plurality of wheels at the time of the brake operation, and controlling the fluid pressure of the wheel cylinder,
Detection means for detecting a failure of the wheel when the difference between the hydraulic pressure of the wheel cylinder in one wheel and the hydraulic pressure of the wheel cylinder in the other wheel exceeds a predetermined value. Have
The detecting means includes a hydraulic pressure in the wheel cylinder in the one wheel in a state in which a holding valve provided corresponding to the wheel cylinder of each wheel is closed, and a wheel cylinder in the other wheel. When the absolute value of the difference from the hydraulic pressure of the wheel is larger than a predetermined value and the rate of change of the wheel cylinder with the lower hydraulic pressure is smaller than a predetermined negative value, Make a second failure detection to detect,
The control device shuts off the hydraulic pressure supply from the hydraulic pressure source to the wheel cylinder of the wheel in which the failure is detected by the detection means, and in the wheels other than the wheel in which the failure is detected. A brake fluid pressure control device for controlling a fluid pressure of the wheel cylinder. The control device obtains a hydraulic gain of a normal wheel next to the wheel in which the failure is detected and a second normal wheel located on a diagonal of the normal wheel;
The hydraulic gain of a third normal wheel located on a diagonal line of the wheel in which the failure is detected is calculated based on the hydraulic gain of the normal wheel and the second normal wheel. Brake fluid pressure control device. In the brake fluid pressure control device having a control device for communicating the fluid pressure source and the wheel cylinder in each of the plurality of wheels at the time of the brake operation, and controlling the fluid pressure of the wheel cylinder,
Detection means for detecting a failure of the wheel when the difference between the hydraulic pressure of the wheel cylinder in one wheel and the hydraulic pressure of the wheel cylinder in the other wheel exceeds a predetermined value. Have
The wheels are arranged on the front, rear, left and right respectively.
The control device shuts off the hydraulic pressure supply from the hydraulic pressure source to the wheel cylinder of the wheel in which the failure is detected by the detection means, and in the wheels other than the wheel in which the failure is detected. For controlling the hydraulic pressure of the wheel cylinder,
The control device obtains a hydraulic gain of a normal wheel next to a wheel in which a failure is detected and a second normal wheel located on a diagonal of the normal wheel,
A brake that calculates a hydraulic gain of a third normal wheel located on a diagonal line of the wheel in which the failure is detected, based on the hydraulic gain of the normal wheel and the second normal wheel. Hydraulic control device. In the brake fluid pressure control device having a control device for communicating the fluid pressure source and the wheel cylinder in each of the plurality of wheels at the time of the brake operation, and controlling the fluid pressure of the wheel cylinder,
Detection means for detecting a failure of the wheel when the difference between the hydraulic pressure of the wheel cylinder in one wheel and the hydraulic pressure of the wheel cylinder in the other wheel exceeds a predetermined value. Have
The control device shuts off the hydraulic pressure supply from the hydraulic pressure source to the wheel cylinder of the wheel in which the failure is detected by the detection means, and in the wheels other than the wheel in which the failure is detected. For controlling the hydraulic pressure of the wheel cylinder,
Said detecting means is under the braking control request by depression of the brake pedal, but before Symbol normal control target control amount of the hydraulic pressure in the wheel cylinder is calculated based on the operation amount of the brake pedal, the lost A brake fluid pressure control device characterized by performing a failure determination.

Images