JP2006290095A - Brake controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake controller capable of identifying a failed pressure reducing valve without depending upon an accumulator. <P>SOLUTION: This brake controller includes an intensifying valve for controlling an intensifying amount in respective wheel cylinders; the pressure reducing valve for controlling a pressure reducing amount in the respective wheel cylinders; and a hydraulic circuit for independently controlling hydraulic pressure of the respective wheel cylinders by controlling the intensifying valve or the pressure reducing valve based on a detected signal of a hydraulic pressure sensor. A control unit performs two types of control: failure detection control for detecting failure in the pressure reducing valve based on a hydraulic pressure supply source operating state or hydraulic pressure change state in the wheel cylinder; failure occurring valve identifying control for identifying which of the respective pressure reducing valves has failure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a brake control device that generates hydraulic pressure by driving a pump and provides braking force to wheels.

Conventionally, there is a technique disclosed in Patent Document 1 as a brake control device without an accumulator. In this technique, at least one or more wheel cylinders are increased by one pump. In addition, a hydraulic pressure control means, a hydraulic pressure sensor, and a pressure reducing valve are provided. The pressure reducing valve is shut off at the time of pressure increase / holding, and opened at the time of pressure reducing to release the hydraulic pressure, thereby controlling the wheel cylinder pressure. Yes.
Special Table 2002-533263

  Here, when the pressure reducing valve leaks due to the failure, the pressure increasing / holding function is impaired. Therefore, the pump pressure is recirculated to the low pressure side via the leaked pressure reducing valve, and not only the leaked pressure reducing valve side wheel cylinder but also the normal pressure reducing valve side wheel cylinder does not increase in pressure. Depending on the comparison, there is a problem that it is impossible to specify which pressure reducing valve has failed.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a brake control device capable of specifying a failed pressure reducing valve.

  In order to achieve the above object, in the present invention, a hydraulic pressure generating source that supplies brake hydraulic pressure to each wheel cylinder provided on each of a plurality of wheels based on an output signal from a control unit, A hydraulic pressure sensor that detects the hydraulic pressure of the wheel cylinder, and is interposed between the discharge side of the hydraulic pressure supply source and each of the wheel cylinders, and enters each wheel cylinder based on a command from the control unit. A pressure increasing valve for controlling the pressure increasing amount, and a discharge side of the hydraulic pressure supply source is an upstream side, and each of the wheel cylinders is interposed on the downstream side of each of the wheel cylinders and based on a command from the control unit. A pressure reducing valve that controls the amount of pressure reduced inward, and the pressure increasing valve and the pressure reducing valve based on a detection signal of the hydraulic pressure sensor to control each of the foil wheels. And a hydraulic pressure circuit for independently controlling the hydraulic pressure of the brake, wherein the control unit is based on an operating state of the hydraulic pressure supply source or a hydraulic pressure change state in the wheel cylinder. An abnormality detection control for detecting an abnormality of the pressure reducing valve, and when an abnormality of the pressure reducing valve is detected, an opening degree of the pressure increasing valve is changed to generate a hydraulic pressure difference between the wheel cylinders, thereby reducing each pressure reducing valve. An abnormality occurrence valve specifying control for specifying which of the valves is abnormal is executed.

  Therefore, it is possible to provide a brake control device that can identify a failed pressure reducing valve by generating a hydraulic pressure difference of the wheel cylinder accompanying a change in the degree of opening of the pressure increasing valve.

  Hereinafter, the best mode for realizing the brake control device of the present invention will be described based on the embodiments shown in the drawings.

[Hydraulic circuit diagram]
Example 1 will be described with reference to FIGS. FIG. 1 is a hydraulic circuit diagram of the brake control device of the present application. In the present application, since the rear wheel side is a brake system that electrically obtains a braking force, only the front wheel side hydraulic circuit is shown, but the rear wheel side may obtain the braking force by hydraulic pressure without any particular limitation.

  In the first embodiment, the motor / pump operation detects the no-load state for a predetermined time while the motor torque is constant (no-load state; pressure-reducing valve complete leak, pump discharge amount = pressure-reducing valve leak amount). This is an example of detecting a leak.

  The hydraulic circuit in the present application is a tandem type unit composed of a P system connected to the left front wheel and an S system connected to the right front wheel. Both the left and right FL and FR wheels are connected to the same pump P and are driven by a motor M. The motor M is controlled by the control unit 10 using the battery B as a power source.

  The master cylinder 1 is connected to the wheel cylinders 5 and 5 through oil passages 31 and 32, normally open shut-off valves 21 and 22, and oil passages 33 and 34. The pump P is a one-way pump, the suction side is connected to the reservoir 8 via the oil passage 41, and the discharge side is connected to the oil passages 43 and 44. The master cylinder 1 is provided with a stroke sensor 2 and a stroke simulator 3 that detect the pedaling force of the driver, and outputs a detection signal to the control unit 10.

  The oil passages 43 and 44 are provided with normally open proportional pressure increasing valves 23 and 24, which are connected to the oil passages 45 and 46, respectively. The oil passages 45 and 46 are provided with pressure reducing valves 25 and 26 that are normally closed proportional valves, and are connected to the oil passage 41. The oil passages 43 and 44 are provided with check valves 27 and 28 that allow only the flow from the pump P to the pressure increasing valves 23 and 24. Furthermore, a relief valve 30 for releasing excess discharge pressure is provided in an oil passage 47 that connects the oil passages 43 and 44 and the oil passage 41.

  Hydraulic pressure sensors 51 and 52 for detecting the master cylinder pressure are provided between the master cylinder 1 and the shut-off valves 21 and 22 in the oil passages 31 and 32. The oil passages 33 and 34 are also provided with hydraulic pressure sensors 53 and 54 for detecting the wheel cylinder pressure. Further, a hydraulic pressure sensor 55 for detecting the pump discharge pressure is also provided on the discharge side of the pump P. The detected hydraulic pressure is output to the control unit 10.

(When pressure is increased)
When the pressure is increased, hydraulic oil is pumped from the reservoir 8 through the oil passage 41 by the pump P, and the wheel cylinders 5 and 5 are increased through the normally open pressure increasing valves 23 and 24. At this time, the normally open shut-off valves 21 and 22 are closed, and the master cylinder pressure is not introduced into the wheel cylinders 5 and 5. Further, the pressure reducing valves 25 and 26 are also closed, and the wheel cylinders 5 and 5 and the reservoir 8 are shut off.

(At reduced pressure)
During decompression, the pump P is stopped and the decompression valves 25 and 26 are opened. The normally open shut-off valves 21 and 22 are closed. As a result, the wheel cylinders 5 and 5 communicate with the reservoir 8 through the oil passages 33, 34 and 45, 46, and the oil passage 41, and the wheel cylinder pressure is reduced.

(When holding)
When holding, the pump P is stopped, and the check valves 27 and 28 prevent backflow to the pump side regardless of whether the pressure increasing valves 23 and 24 are opened or closed. Further, the pressure reducing valves 25 and 26 and the shut-off valves 21 and 22 are closed. As a result, the wheel cylinders 5 and 5 are disconnected from the master cylinder 1 and the reservoir 8, and the hydraulic pressure is maintained.

(During fail)
At the time of failure, the solenoid valves 21 to 26 are not energized, the normally open shutoff valves 21 and 22 and the pressure increasing valves 23 and 24 are automatically opened, and the normally closed pressure reducing valves 25 and 26 are closed. . As a result, the master cylinder 1 and the wheel cylinders 5 and 5 are communicated with each other, the wheel cylinders 5 and 5 and the reservoir 8 are shut off, and a manual brake is secured.

[Pressure reducing valve leak detection control (motor no load detection)]
If a leak occurs in either one or both of the pressure reducing valves 25 and 26, the wheel cylinder pressure cannot be increased because the wheel cylinders 5 and 5 and the reservoir 8 communicate with each other during pressure increase / holding. Since the P and S system wheel cylinders 5 and 5 have the same hydraulic pressure as long as the pressure is not increased, the leakage of the pressure reducing valves 25 and 26 cannot be detected simply by comparing the hydraulic pressures of the wheel cylinders 5 and 5. Thus, it is conceivable to increase the wheel cylinder pressure instantaneously by accumulator pressure accumulation, but this is not preferable because it increases the number of parts.

  Here, as shown in the time-motor torque map of FIG. 2, if the pressure reducing valves 25 and 26 are normal, the wheel cylinder pressure is increased and a rotational load is generated on the pump P. Conversely, if leakage occurs in the pressure reducing valves 25 and 26, no rotational load is generated even if the pump P is driven, and the pump P is driven in a no-load state.

  Therefore, in the first embodiment of the present invention, paying attention to this point, when the rotational load of the pump P is not detected after a certain time Δt has elapsed from the start of driving of the pump P, that is, when the motor M is driven in a no-load state. In the control unit 10, it is determined that any one of the pressure reducing valves 25 and 26 has leaked.

  Even when the pressure increasing valves 23 and 24 are normal, the pressure increasing response time varies depending on the number of rotations of the motor M and the degree of opening of the pressure increasing valve. It is determined by reading a map based on the valve opening degree command value of 24 (see FIG. 3).

  In the first embodiment, the leak determination is performed by detecting the no-load torque of the motor. However, the determination may be made using the motor rotation speed. If there is no leak, the pressure is increased and the motor load is increased to decrease the rotational speed. If there is a leak, the pressure is not increased and the motor load is not increased. Therefore, it is possible to make a leak determination in the same manner as in the case of detecting no-load torque for a certain period of time as in the first embodiment by determining a leak when the motor rotation speed increases.

[Leak valve identification control]
Even if the motor M is in a no-load state and a certain time Δt has passed and it is confirmed that a leak has occurred, it is still not specified which of the P and S system pressure reducing valves 25 and 26 has a leak. Can not.

  Therefore, in the first embodiment of the present invention, after the leak is detected, the control unit 10 first determines whether the P system pressure reducing valve 25 is leaking, and then determines whether the S system pressure reducing valve 26 is leaking. In order to determine whether the pressure reducing valves 25 and 26 are leaking, one of the pressure increasing valves 23 and 24 provided in each system is closed and the other is opened, and the pump pressure is supplied to only one of the systems. By doing.

  When the motor M is in a no-load state and the fixed time Δt has elapsed, it is certain that a leak has occurred in either one or both of the pressure reducing valves 25 and 26. Here, for example, when the P system of the P and S system pressure increasing valves 23 and 24 is closed, the S system is opened, and the pump pressure is supplied only to the S system, the S system wheel cylinder pressure is increased by a predetermined value or more. Then, it can be determined that at least the P system pressure reducing valve 25 is leaking. The same applies to the S system.

  When only one of the P and S system pressure reducing valves 25 and 26 is leaking, the control brake is executed only with a normal system. If both are leaking, the two-way fail control is executed to perform forced braking such as engine braking.

  The pressure increasing valves 23 and 24 may reduce the valve opening degree instead of closing one of them. On the side where the degree of valve opening is lowered, the pressure increases due to the orifice effect. Therefore, the leak generation valve can be specified by detecting the increased pressure.

[Pressure reducing valve leak detection control processing (motor no load detection)]
FIG. 4 is a flowchart showing the flow of the pressure reducing valve leak detection control process. Hereinafter, each step will be described.

  In step S101, the driver's intention to decelerate is confirmed by the stroke sensor 2, and the process proceeds to step S102.

  In step S102, a motor drive command is output from the control unit 10 to generate a braking force, and the process proceeds to step S103.

  In step S103, it is determined whether or not the motor M has rotated. If YES, the process proceeds to step S104, and if NO, the process proceeds to step S106.

  In step S104, it is determined whether or not the motor M has been driven at a constant time Δt with no-load torque Ta. If YES, the process proceeds to step S105, and if NO, the process proceeds to step S107.

  In step S105, the leak of any of the pressure reducing valves 25 and 26 is detected, and the process proceeds to step S200 to specify the leak occurrence valve.

  In step S106, it is determined that there is an abnormality in the motor M, the failure control is executed, and the control is terminated.

  In step S107, the pressure reducing valves 25 and 26 are both normal, normal brake control is executed, and the control is terminated.

[Leak generating valve specific control processing]
FIG. 5 is a flowchart of the leak occurrence valve specifying control process in step S200 of FIG.

  In step S201, the P system pressure increasing valve 23 is closed, the S system pressure increasing valve 24 is opened, the S system pressure reducing valve 26 is closed, and the process proceeds to step S202.

  In step S202, based on the detected value of the hydraulic pressure sensor 54, it is determined whether or not only the S-system wheel cylinder 5 has increased pressure by a predetermined value or more. If YES, the process proceeds to step S208, and if NO, the process proceeds to step S203. .

  In step S203, the S system pressure reducing valve 26 fails, and the process proceeds to step S204.

  In step S204, the P system pressure increasing valve 23 is opened, the S system pressure increasing valve 24 is closed, the P system pressure reducing valve 25 is closed, and the process proceeds to step S205.

  In step S205, based on the detection value of the hydraulic pressure sensor 53, it is determined whether or not only the P-system wheel cylinder 5 has increased pressure by a predetermined value or more. If YES, the process proceeds to step S210, and if NO, the process proceeds to step S206. .

  In step S206, the P system pressure reducing valve 25 is failed, and the process proceeds to step S207.

  In step S207, the pressure reducing valves 25 and 26 of both P and S systems are failed, the control at the time of both failures is executed, and the control is terminated.

  In step S208, from the result of step S202, the S system pressure reducing valve 26 is made normal, and the P system pressure reducing valve 25 is failed, and the process proceeds to step S209.

  In step S209, braking is executed only in the S system, and the control is terminated.

  In step S210, the P system pressure reducing valve 25 is normal, and the process proceeds to step S211.

  In step S211, braking is executed only in the P system, and the control is terminated.

[Contrast between the effects of the conventional example and the embodiment of the present application]
In the conventional example, when the pressure reducing valve fails and a leak occurs, the pump pressure is recirculated to the low pressure side through the leaked pressure reducing valve, and each wheel cylinder pressure has the same value regardless of the presence or absence of the leak. It becomes. Therefore, it cannot be specified in which pressure reducing valve the failure has occurred by comparing the hydraulic pressures. Thus, it is conceivable to increase the wheel cylinder pressure instantaneously by accumulator pressure accumulation, but this is not preferable because it increases the number of parts.

  Therefore, in the first embodiment of the present invention, when the rotational load of the pump P is not detected after the lapse of a fixed time Δt from the start of driving of the pump P, that is, when the motor M is driven in a no-load state, the control unit 10 It is determined that any one of the pressure reducing valves 25 and 26 has leaked.

  After the leak is detected, the presence or absence of one of the P and S system pressure reducing valves 25 and 26 is determined, and then the presence or absence of the other leak is determined. The determination of the presence / absence of leakage is performed by closing one of the pressure increasing valves 23 and 24 provided in each system and opening the other, and supplying pump pressure to only one of the systems. When only one of the P and S system pressure reducing valves 25 and 26 is leaking, braking is performed only with a normal system, and when both are leaking, both fail control such as engine stop is performed.

  As a result, it is possible to provide a brake control device that can quickly detect the failure of the pressure reducing valve and identify the failed pressure reducing valve without using an accumulator.

  A second embodiment will be described with reference to FIGS. Since the basic configuration is the same as that of the first embodiment, only different points will be described. In the first embodiment, leakage of the pressure reducing valves 25 and 26 is detected based on whether or not the motor M is rotating in a no-load state, but in the second embodiment, it is determined whether or not the wheel cylinder pressure is equal to or higher than a predetermined threshold value. The leak of the pressure reducing valves 25 and 26 is detected.

  That is, in Example 2, although the motor torque is increased by the operation of the motor / pump, the time required for reaching the hydraulic pressure threshold is too long (hydraulic valve micro leak, pump discharge amount> pressure reducing valve leak amount). It is an example. The leak valve specification after the leak detection is the same as in the first embodiment.

[Pressure reducing valve leak detection control (hydraulic pressure threshold judgment and hydraulic pressure gradient detection)]
In the hydraulic circuit of the brake control device of the present application, the wheel cylinders 5, 5 and the discharge side of the pump P communicate with each other via the pressure increasing valves 23, 24. Therefore, when the pressure increasing valves 23, 24 are opened, the wheel cylinder pressure The pump discharge pressure is the same.

  Therefore, in the second embodiment, paying attention to this point, if the pump discharge pressure does not increase when the pump P is driven, it is determined that any of the pressure reducing valves 25 and 26 is leaking. Even when the time gradient of the hydraulic pressure is negative despite the holding control time, it can be determined that the pressure reducing valves 25 and 26 are leaking.

  That is, as shown in FIG. 7, if the pump discharge pressure does not exceed the threshold Pa even after a certain time Δt has elapsed after the start of the pump P operation, a leak occurs in the pressure reducing valves 25 and 26. Judge that Even when the pressure is equal to or greater than the threshold value Pa, if the time gradient ΔPwc of the wheel cylinder pressure Pwc is negative at the time of holding (leak 2: two-dot chain line), it is determined that a leak has occurred.

  Here, since the pressure increase response of the pump discharge pressure differs depending on the rotational speed of the motor M and the degree of opening of the pressure reducing valves 25 and 26, the fixed time Δt and the threshold value Pa are set to It is determined by reading a map based on the valve opening degree command values of the current pressure increasing valves 23 and 24. Since the map is the same as that in FIG.

[Pressure reduction valve leak detection control processing (hydraulic pressure threshold judgment and hydraulic pressure gradient detection)]
FIG. 6 is a flowchart of the pressure reducing valve leak detection control process in the second embodiment. Hereinafter, each step will be described.

  Steps S301 to S303 are the same as steps S101 to S103 in the flowchart of FIG.

  In step S304, time measurement is started, and the process proceeds to step S305.

  In step S305, it is determined whether or not the predetermined time Δt has elapsed. If YES, the process proceeds to step S306, and if NO, the time measurement is continued.

  In step S306, it is determined whether or not the wheel cylinder pressure Pwc is greater than or equal to the threshold value Pa. If YES, the process proceeds to step S309, and if NO, the process proceeds to step S307.

  In step S307, it is determined that a failure has occurred in either or both of the pressure reducing valves 25 and 26, and the process proceeds to step S200 to specify the leak generating valve (see FIG. 5).

  In step S308, it is determined that there is an abnormality in the motor M, the failure control is executed, and the control is terminated.

  In step S309, the motor M is stopped, the pressure reducing valves 25 and 26 are closed to perform holding control, and the process proceeds to step S310.

  In step S310, it is determined whether or not the value of the time gradient ΔPwc of the wheel cylinder pressure Pwc at the time of holding is negative. If YES, the process proceeds to step S307, and if NO, the process proceeds to step S311.

  In step S311, the pressure reducing valves 25 and 26 are both normal, normal brake control is executed, and the control is terminated.

[Effect in Example 2]
In the second embodiment, when the pump discharge pressure does not increase when the pump P is driven, it is determined that any one of the pressure reducing valves 25 and 26 has a leak. In addition, even when the hydraulic pressure time gradient is negative despite the holding control, it is determined that the pressure reducing valves 25 and 26 are leaking. Thereby, the same effect as Example 1 can be acquired. By combining the motor load detection of the first embodiment and the hydraulic pressure detection of the second embodiment, the fail detection control of the pressure reducing valves 25 and 26 can be executed with higher accuracy.

(Other examples)
The best mode for carrying out the present invention has been described based on the embodiments. However, the specific configuration of the present invention is not limited to each embodiment, and the scope of the invention is not deviated. Design changes and the like are included in the present invention.

  In the first embodiment, the leak determination is performed by detecting the no-load torque of the motor. However, the determination may be made using the motor rotation speed. If there is no leak, the pressure is increased and the motor load is increased to decrease the rotational speed. If there is a leak, the pressure is not increased and the motor load is not increased. Therefore, when the motor rotational speed increases, it is possible to obtain the same effect as that of the first embodiment by determining that the leak is present.

  Further, technical ideas other than the claims that can be grasped from the above embodiments will be described below together with the effects thereof.

(A) In the brake control device according to claim 1,
In the abnormality occurrence valve specifying control, when one of the pressure increasing valves is closed and the other is opened, if the other wheel cylinder pressure does not increase more than a predetermined value, at least the pressure reducing valve on the opened side is abnormal. Judge that

  An abnormal pressure reducing valve can be detected quickly.

(B) In the brake control device according to claim 1,
When the abnormal pressure reducing valve is specified in the abnormality generating valve specifying control, the braking force is generated only by the wheels provided in the normal pressure reducing valve.

  The system in which an abnormality has occurred can be disconnected and fail-safe control can be executed promptly.

It is a hydraulic circuit diagram of the present brake control device. 2 is a time-motor torque (or rotation speed) map in the first embodiment. It is a pressure increase valve opening degree in Example 1-fixed time (DELTA) t map. 3 is a flowchart of a pressure reducing valve leak detection control process in the first embodiment. It is a flowchart of the leak generation valve specific control process in step S200 of FIG. 7 is a flowchart of a pressure reducing valve leak detection control process in Embodiment 2. 10 is a time-threshold value map according to the second embodiment.

Explanation of symbols

1 Master Cylinder 2 Stroke Sensor 3 Stroke Simulator 5 Wheel Cylinder 8 Reservoir 10 Control Units 21 and 22 Shutoff Valves 23 and 24 Pressure Boosting Valves 25 and 26 Pressure Reducing Valves 27 and 28 Check Valve 30 Relief Valves 31 to 34 Oil Path 41 Oil Path 43 ~ 47 Oil passage 51 ~ 55 Hydraulic pressure sensor

Claims (1)

A hydraulic pressure source for supplying brake hydraulic pressure to each wheel cylinder provided on each of the plurality of wheels based on an output signal from the control unit;
A hydraulic pressure sensor for detecting the hydraulic pressure of each wheel cylinder;
A pressure increasing valve that is interposed between the discharge side of the hydraulic pressure supply source and each wheel cylinder, and controls the amount of pressure increase in each wheel cylinder based on a command from the control unit;
A pressure reducing valve that controls the amount of pressure reduction in each wheel cylinder based on a command from the control unit, with the discharge side of the hydraulic pressure supply source being an upstream side and being interposed on the downstream side of each wheel cylinder. When,
A brake control device comprising: a hydraulic circuit that independently controls the hydraulic pressure of each wheel cylinder by controlling the pressure increasing valve and the pressure reducing valve based on a detection signal of the hydraulic pressure sensor;
The control unit includes an abnormality detection control for detecting an abnormality of the pressure reducing valve based on an operating state of the hydraulic pressure supply source or a hydraulic pressure change state in the wheel cylinder;
When an abnormality of the pressure reducing valve is detected, the opening of the pressure increasing valve is changed to generate a hydraulic pressure difference between the wheel cylinders, thereby specifying which of the pressure reducing valves is abnormal. A brake control device characterized by executing abnormality occurrence valve specifying control.

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