JP2002029404A - Brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately detect abnormality of a solenoid valve without generating an operating sound. SOLUTION: An operation check for determining whether the solenoid valve is normally operated or not is executed by energizing a control unit executing ABS control for such a short time as not to actuate the solenoid valve. An abnormity detecting means determining the abnormality based on the results is provided. The abnormality detecting means is so constituted that, when the abnormality determinations are performed a prescribed plurality of times by the operation check, it makes the final determination to be abnormal, and when the abnormality determinations are made but the frequencies do not reach the prescribed plurality of times, it does not make the final determination to be abnormal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake control device for executing ABS control for preventing wheels from locking during braking, and more particularly to a technique for checking whether a solenoid valve operates normally.

[0002]

2. Description of the Related Art Conventionally, the wheel speed is detected during braking, and when the wheels tend to lock, the brake fluid pressure is reduced, held, and increased to prevent the wheels from locking and to minimize the braking distance. There is known a brake control device that executes ABS control. In such a brake control device, it is occasionally checked whether the solenoid valve provided in the device functions normally, and in an emergency where ABS control is required,
Make sure it works. In other words, the ABS control often operates infrequently, and cannot detect the malfunction of the device during normal traveling. In addition, if the solenoid valve is not used for a long time, the valve body may be stuck and the valve body may not operate even when the power is supplied.

Therefore, as an apparatus for solving the above-mentioned problem, an apparatus described in Japanese Patent Application Laid-Open No. H11-301441 is known. This prior art includes a first detecting means for conducting an electrical check by energizing for a short time such that the electromagnetic valve is not driven, and energizing for a time during which the electromagnetic valve is actually driven when the first detecting means determines that there is an abnormality. The second to check for abnormalities
Abnormality detection is performed by the detection means. Therefore,
Generation of driving noise of the solenoid valve can be greatly reduced, and an abnormality can be reliably detected.

[0004]

However, in the above-mentioned prior art, there is a case where an abnormality is determined when noise is superimposed when the first detecting means is energizing the solenoid valve. However, since the solenoid valve is actually operated by performing the second detection means even though it is actually normal, there is a problem that an operation sound is generated and discomfort is given to the occupant.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to execute high-precision detection of a solenoid valve abnormality without generating operation noise.

[0006]

[Means for Solving the Problems]

According to the present invention, when the abnormality of the solenoid valve is detected, an operation check is performed to determine whether or not the solenoid valve operates normally by conducting electricity for a short time without operating the solenoid valve. . If the abnormality check is made a plurality of predetermined times by this operation check, it is finally determined that there is an abnormality. However, if the number of times is not the predetermined number of times even if the abnormality determination is made, it is finally determined that there is an abnormality. do not do. Therefore, when performing the operation check, noise is superimposed,
Even if the noise is determined to be abnormal, if the noise is temporary, the number of times of determining the abnormality does not reach a predetermined number of times, and the final determination is not abnormal. In addition, when an abnormality is truly occurring, the number of times of abnormality determination by the operation check exceeds a predetermined number of times, and in this case, the abnormality is determined without actually flowing a current for driving the solenoid valve. A final decision can be made. As described above, it is possible to perform abnormality detection with high accuracy without causing discomfort to the occupant by actually operating the solenoid valve to generate an operation sound and without being affected by noise. Is obtained.

[0007] Further, in finally performing the abnormality determination,
In the invention described in claim 2, it is assumed that the number of times of abnormality determination at the time of performing the operation check is equal to or greater than a predetermined number of times set in advance. By setting the number of times of abnormality determination in this way, it is possible to eliminate temporary superimposition of noise, and if an abnormality has occurred, it is possible to reliably detect the abnormality and improve the accuracy of abnormality detection. Can be higher. In the third aspect of the present invention, it is assumed that, when finally performing the abnormality determination, the abnormality determination at the time of performing the operation check is performed continuously for a predetermined number of times or more. As described above, when the abnormality determination is made more than the predetermined number of times continuously, it is possible to eliminate the superimposition of the temporary noise, and when the abnormality has occurred, it is necessary to make sure that this is not the case. And abnormality detection accuracy can be increased. Further, in the invention described in claim 4, when the abnormality determination is finally performed, it is assumed that the number of abnormality determinations when the operation check is performed a plurality of times is when the majority of the number of operation checks is satisfied. In this way, when the abnormality is determined by more than a majority, it is possible to eliminate the superimposition of temporary noise and, when an abnormality has occurred, to reliably detect this. And the abnormality detection accuracy can be increased.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 First, the configuration will be described. FIG. 1 is a hydraulic circuit diagram showing an oil passage configuration in the brake control device according to the first embodiment, in which WC indicates a wheel cylinder. In addition, the code in parentheses, FL is the wheel cylinder of the left front wheel, FR is the wheel cylinder of the right front wheel, R
Indicates a wheel cylinder of the rear wheel. The wheel cylinders WC for the rear wheels are provided on the left and right wheels, respectively. However, in the present embodiment, only one wheel cylinder WC is shown in the drawing because they are controlled to the same pressure. The rear wheel may be configured in the same manner as the front wheel so that the left and right sides can be independently hydraulically controlled. These wheel cylinders WC are connected to the master cylinder MC via the brake circuits 1 and 2, and the left and right front wheel cylinders WC (FL), W
A brake circuit 1 connected to C (FR) and a brake circuit 2 connected to wheel cylinders WC (R) of left and right rear wheels
And two systems are provided. In the following description, the wheel cylinders WC (FL) (FR) (R) will be described as WC only when no specific one is indicated.

The front-wheel-side brake circuit 1 includes a wheel cylinder WC (FL), (FR) for each front wheel at a branch point 1d.
And an inflow valve 5 is provided in the middle of each of the branch circuits 1L and 1R.
An inflow valve 5 is also provided in the middle of the brake circuit 2. These inflow valves 5 are constituted by normally open two-port two-position electromagnetic switching valves which make the respective circuits 1L, 1R, 2 communicate with each other by a spring force when they are not operated, and shut them off when they are operated (when energized). ing. In addition, each inflow valve 5
Is provided with a bypass passage 1h which bypasses the bypass passage 1h. The bypass passage 1h is provided with a one-way valve 1g which allows only a return from a downstream (wheel cylinder WC side) to an upstream (master cylinder MC side).

A drain circuit 10 for connecting the brake circuits 1 and 2 and the reservoir 7 is connected downstream of the inflow valve 5. The drain circuit 10 is provided with the outflow valve 6. These outflow valves 6 are normally closed 2-port 2-position electromagnetic switching valves that shut off the drain circuit 10 when not in operation and communicate with the drain circuit 10 when in operation.

The drain circuit 10 is connected via a recirculation circuit 11 to a position upstream of the inflow valve 5 of each of the brake circuits 1 and 2. Further, pumps 4 and 4 for returning the brake fluid stored in the reservoir 7 to the brake circuits 1 and 2 are provided in the middle of the return circuit 11. Each of these pumps 4 is a plunger-type pump that performs suction and discharge by changing the volume of a volume chamber as the plunger 4p slides, and is operated by driving a motor M.
Each pump 4 has a suction valve 4 having a one-way valve structure.
a, a discharge valve 4b is provided, and a pulsation absorbing damper 4d is provided on the discharge side.

[0012] Of the configurations described above, the configuration surrounded by a chain line BU in Fig. 1 is a brake unit, which is collectively housed in a housing (not shown).

As shown in FIG. 2, the switching of the valves 5 and 6 of the electromagnetic valve structure and the driving of the motor M which is the driving source of the pump 4 are controlled by a control unit CU as ABS control means. That is, the control unit CU includes a wheel speed sensor S for detecting the rotation speed of each wheel (not shown), a brake switch BS that switches in accordance with the driver's depression of the brake pedal BP, and a G for detecting the longitudinal and lateral acceleration of the vehicle. Sensor group S having sensor GS and the like
G is connected, and the control unit CU obtains the wheel speed Vw of each wheel based on the signal input from the sensor group SG, and reduces the wheel speed Vw during braking by the pressure reduction obtained from the pseudo vehicle body speed Vi. When the threshold value becomes lower than the threshold value λ1 (when the slip ratio of the wheel becomes equal to or more than a predetermined value), the ABS control for preventing the wheel from being locked is performed.

FIG. 3 is a flowchart showing a basic control flow in the ABS control of the present embodiment. In step S1, a signal is read from each wheel speed sensor S,
The wheel speed Vw of each wheel is calculated. In the following step S2, the rate of change of each wheel speed Vw, that is, the wheel acceleration △ Vw
Is calculated. In step S3, a pseudo vehicle speed Vi is determined. The pseudo vehicle speed Vi is formed by the largest value among the wheel speeds Vw. In step S4, a process of obtaining a pressure reduction threshold value λ1 for each wheel is performed. In step S5, the wheel speed Vw of each wheel is reduced to the pressure reduction threshold λ.
1 is determined, and if Vw ≦ λ1, step S
6, and if Vw> λ1, the process proceeds to step S10. In step S6, it is determined whether or not an ABS flag AS described later is set (AS = 1). If AS = 1, the process proceeds to step S7, the slip counter TSLP is incremented, and if AS = 0, the process proceeds to step S7. Proceed to S8. In step S8, it is determined whether or not the wheel acceleration △ Vw is less than a positive predetermined value B, and if △ Vw <B, the process proceeds to step S9.
If Vw ≧ B, the process proceeds to step S11. In step S10, it is determined whether the wheel acceleration △ Vw is less than a negative predetermined value A including 0, and the process proceeds to step S12 when で Vw <A.
If ΔVw ≧ A, the process proceeds to step S11. In step S9, the pressure increasing process is performed, that is, the inflow valve 5 is opened while the outflow valve 6 is closed. In step S11, a holding process is executed, that is, the inflow valve 5 is closed and the outflow valve 6 is also closed. In step S12, a decompression process is performed, that is, the inflow valve 5 is closed while the outflow valve 6 is opened.
The ABS control flag AS indicating that the pressure control of the wheel cylinder WC based on the S control is being executed is set to 1, the slip counter TSLP is reset to 0, and the driving of the motor M is started. By the way,
The slip counter TSLP measures an area where the wheel speed Vw does not need to be reduced in the state of AS = 1, and in this embodiment, measures a time during which the wheel speed Vw is a value larger than the pressure reduction threshold λ1. In the present embodiment, since the pseudo vehicle speed Vi indicates the largest value of each wheel speed Vw, the slip counter T
The measured value of the SLP is a time during which the wheel speed Vw falls within a range between the pseudo vehicle body speed Vi and the pressure reduction threshold value λ1.

In step S13 to which the processing proceeds after performing any one of the above-described steps S9, S11 and S12, it is determined whether or not AS = 1. If AS = 1, the processing proceeds to step S20 to execute ABS termination control. One flow ends when AS = 0. Incidentally, the ABS termination control is performed when the time measured by the slip counter TSLP exceeds a predetermined value.
This is executed as a result of the BS control flag AS being reset to 0, and mainly consists of a process of reliably returning the brake fluid stored in the reservoir 7 to the master cylinder MC.

Next, abnormality detection control which is a feature of the present embodiment will be described. (Embodiment 1) This embodiment 1 corresponds to the first and third aspects of the present invention. FIG.
It is a flowchart which performs abnormality detection control. Step S
At 101, initialization is performed. Here, a counter, a flag, and the like described later are reset. Step S102
Then, it is determined whether or not the normal end flag has been set. If the normal end flag has been set, the abnormality detection control is terminated as it is. On the other hand, step S102
If the normal end flag is not set in step, the process proceeds to step S103. In step S103, ABS
It is determined whether or not control is being performed. If non-ABS control is being performed, the process proceeds to step S104. If ABS control is being performed, the process returns to step S102. In step S104,
It is determined whether or not the vehicle speed is higher than a predetermined value, that is, whether or not the vehicle is running at or above the predetermined speed. When the vehicle is running at or above the predetermined speed, the process proceeds to step S105. Return. In step S105, it is determined whether or not the brake switch BS is ON, that is, whether or not braking is being performed. The process returns to step S102 during braking, and proceeds to step S106 when braking is not performed. In step S106, the inflow valve 5 and the outflow valve 6 which are solenoid valves
It is determined whether or not a drive signal for abnormality detection is being output toward the device. If the drive signal is being output, the process proceeds to step S107. If the drive signal is not being output, step S114 is performed.
And outputs the drive signal. In step S107, an analog electric signal is taken in from a drive circuit that drives both valves 5 and 6. In step S108, the output of the drive signal to both valves 5 and 6, which are electromagnetic valves, is stopped.

In the first embodiment, the abnormality detection control is executed immediately after the start of the vehicle.
The control is not being executed, the vehicle is running at a predetermined vehicle speed or more,
This is executed when no braking is performed. The drive signal output to both valves 5 and 6 in accordance with the operation check is a short-time energization that does not actually drive a valve body (not shown) in both valves 5 and 6. The time corresponds to a time for executing the flow shown in FIG. 4 once in the first embodiment.

In step S109, step S107
It is determined whether or not the analog signal fetched indicates an abnormality. If it indicates an abnormality, the process proceeds to step S111, but if there is no abnormality, the process proceeds to step S110 to set a normal end flag. That is, in the first embodiment, once it is determined that the operation is normal, the normal end flag is set, and thereafter, the abnormality determination, that is, the operation check is not performed.

If an abnormality is determined in step S109, the process proceeds to step S111, where the counter is incremented. That is, when an operation check is performed and an abnormality is determined, the number of times is counted.
In step S112, it is determined whether or not the number of counters is equal to or greater than a predetermined number N. If the number is less than the predetermined number N, the process returns to step S102 to repeat the operation check. If there is
Proceeding to step S113, abnormality determination (final abnormality determination) is performed.

Next, the operation of the first embodiment will be described.
In the abnormality detection control according to the first embodiment, when the ABS control is not performed, when the vehicle is running at a speed exceeding a predetermined vehicle speed, and when braking is not performed, the valves 5 and 6 are compared with the valves 5 and 6. Starts an operation check that outputs a drive signal that does not actually drive, and if it is determined that the operation is normal in the first operation check, a normal end flag is set (step S102 → S10).
3 → S104 → S105 → S106 → S107 → S10
8 → S109 → S110), it is determined to be normal. Next, when it is determined that the operation is abnormal in the first operation check, the operation check is repeated, and the number of times of abnormality determination is accumulated in the counter (step S109 → S111 →).
(Based on the flow of S112).

In a normal state, whether the operation is determined to be normal at the first operation check or even if it is temporarily determined to be abnormal due to superimposition of noise or the like, the count value of the counter is set to N times which is the set number of times. Before exceeding, in step S109, it is determined that it is normal, and the process proceeds to step S110, where a normal end flag is set.

On the other hand, if an abnormality has really occurred, the operation check is repeated, and it is determined that the abnormality is abnormal even if the operation check is performed many times, and the number of times of this abnormality determination exceeds the set value N. That is, step S1
It becomes a flow of 12 → S113, and is determined to be abnormal.

As described above, the first embodiment is a means for performing only an operation check that does not actually drive the two valves 5 and 6 which are electromagnetic valves. Erroneous judgments can be eliminated, and when a real abnormality occurs, the abnormality can be reliably detected, and the abnormality detection accuracy is improved while preventing the occupant from feeling discomfort due to the operation noise. The effect that it can be obtained is obtained.

(Embodiment 2) Embodiment 2 corresponds to the first and fourth aspects of the present invention. FIG.
Is a flowchart showing the flow of abnormality detection control in the second embodiment. The same processes as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Only the processes different from the first embodiment will be described. I do.

In step S210, the second counter C2
Is incremented. The second counter C2 counts the number of times of abnormality detection. In step S211, the first counter C1 is incremented. This first
The counter C1 counts the number of times that the operation check has been performed. In step S212, the first counter C
It is determined whether or not the count number of the first counter C has reached a predetermined number N. If the count number of the first counter C1 is the predetermined number N, the process proceeds to step S213. If C1 is less than the predetermined number N, the process proceeds to step S213. Returning to S102, the operation check is repeated. In step S213, it is determined whether or not the count number of the second counter C2 is a majority of the predetermined number N. If C2 is a majority of N times, the process proceeds to step S214 and is determined to be abnormal, and C2 is determined. If the count number is less than the majority, the process proceeds to step S215 to set a normal flag.

Next, the operation of the second embodiment will be described. The difference from the first embodiment will be described. In the second embodiment, the operation check is performed N times, and when the number of abnormality determinations among the N times exceeds a majority, it is finally determined that the abnormality is abnormal. If the abnormality determination does not exceed a majority, it is determined to be normal. Therefore, also in the case of the second embodiment,
In the case where noise is superimposed, the number of abnormality determinations by the operation check does not exceed a majority of the number of operation checks (N times), and no erroneous detection is performed. Since the number of times of abnormality determination exceeds the majority of N times, abnormality can be reliably detected.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and a design change or the like may be made without departing from the gist of the present invention. Even if present, it is included in the present invention. For example, in the embodiment, the ABS unit BU that performs only the ABS control is shown as the brake unit. However, the present invention is not limited to this. In order to control the vehicle speed by generating a braking force, or to generate a yaw moment in the vehicle in a direction to stabilize the vehicle, a brake unit that can generate a braking force on a desired wheel is also used. Can be applied. In the second embodiment, C2 ≧ N / 2 is set in step S213, but it may be determined whether or not C2 ≧ N / 2. In this case, for example, C2 ≧ A (predetermined value =
A) It is determined whether or not, and if C2 ≧ A, it is determined to be abnormal,
If C2 <A, a normal end flag is set.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing a configuration of an anti-skid control device according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing a configuration of a main part in the first embodiment.

FIG. 3 is a flowchart showing a basic control flow of ABS control in the first embodiment.

FIG. 4 is a flowchart showing a flow of abnormality detection control in the first embodiment.

FIG. 5 is a flowchart illustrating a flow of abnormality detection control according to the second embodiment.

[Explanation of symbols]

 1h Bypass path 1, 2 Brake circuit 1g One-way valve 1d Branch point 1L, 1R Branch circuit 4d Damper 4p Plunger 4 Pump 4b Discharge valve 4a, Suction valve 5 Inflow valve 6 Outflow valve 7 Reservoir 10 Drain circuit 11 Reflux circuit BP Brake pedal BS Brake switch BU ABS unit CU Control unit GS G sensor M Motor MC Master cylinder S Wheel speed sensor TSLP Slip counter Vi Simulated vehicle speed Vw Wheel speed WC Wheel cylinder

Claims (4)

[Claims] 1. A pressure reducing state in which a plurality of solenoid valves are provided and a wheel cylinder is connected to a low pressure side based on opening and closing of the solenoid valves, and a pressure increasing state in which the wheel cylinder is connected to a hydraulic pressure source side. A braking unit capable of detecting a running state of the vehicle, including a wheel speed detecting means for detecting a rotational speed of a wheel of the vehicle, and a wheel speed lower than a predetermined pressure reduction threshold during braking. Sometimes, based on a comparison between the wheel speed and the pressure reduction threshold, ABS control means for executing ABS control for preventing the wheel lock while preventing the brake distance from becoming longer by at least reducing and increasing the pressure of the brake unit. And performing an operation check on the ABS control means to determine whether or not the electromagnetic valve normally operates by energizing for a short time without operating the electromagnetic valve, and based on the result, An abnormality detecting means for performing an abnormality determination, wherein the abnormality detecting means makes a final determination that the abnormality is abnormal when a plurality of abnormality determinations are made by the operation check, and the abnormality determination is performed. If the predetermined number of times is not reached even if the above is performed, the abnormality determination is not performed and the final determination is not performed. 2. The brake control device according to claim 1, wherein the abnormality determination is made a plurality of times when the abnormality determination is made a predetermined number of times or more. 3. The brake according to claim 1, wherein the abnormality determination is performed a plurality of times a predetermined number of times when the abnormality determination is continuously performed a predetermined number of times or more. Control device. 4. The brake control device according to claim 1, wherein the abnormality determination is made a plurality of times when the abnormality determination is made by a majority of the number of times the operation check is performed. .