JP2792189B2 - Wheel speed control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a wheel speed control device for controlling a brake pressure at the time of braking a wheel to avoid a wheel lock, and in particular, to reduce detection sensitivity of a lock state when traveling on a rough road. And a wheel speed control device having a function of preventing unnecessary pressure reduction.

[Conventional technology]

Wheel anti-lock control generally determines slip ratio, wheel deceleration, etc., and compares them with respective thresholds to determine whether the wheel is prone to locking or recovering from locking. I do. Then, based on the determination result, the brake pressure is reduced, re-pressurized, or held.

The control reference values such as the slip ratio and the wheel deceleration used for the determination are obtained based on the wheel speed.However, on a rough road, the signal waveform of the wheel speed largely pulsates due to unevenness of the road surface as compared with the normal road running, and a pseudo The tendency to lock deepens.
Therefore, if the control mode for the normal road is executed as it is, the slip rate or the wheel deceleration exceeds the threshold before the decompression proper time is reached, the decompression is started, and the deceleration is lost, It may cause insufficient deceleration.

Therefore, as a countermeasure, the behavior of all four wheels or two non-driven wheels is monitored, and if the speed change amount of these wheels satisfies a specific condition, the threshold is determined according to the magnitude of the separately prepared bad road index. A method of changing the value is used to reduce the sensitivity of the decompression determination.

JP-A-60-22548, JP-A-64-70256 and JP-A-64-70256 disclose whether or not the wheel speed change amount satisfies a specific condition, that is, whether or not the traveling road surface is a rough road. Kaihei 1-12
Several methods such as those shown in 7448 and the like have been adopted.

In addition, the bad road index is a certain mathematical formula, for example, Japanese Patent Application No. 62-17 / 1987.
In addition to using mathematical functions as proposed in 1813,
A numerical value prepared in advance may be used by indexing from a memory table.

The bad road index is, for example, as shown in FIG. 6, when it is detected that the amount of change in each wheel speed (wheel acceleration) exceeds a certain amplitude a and exceeds a certain frequency b, or a wheel deceleration. Is incremented when it is detected that the time change amount of the data exceeds a predetermined value. The method of adding the bad road index at this time is to add a value obtained by multiplying the number of wheels that meet specific conditions, or to add a constant value regardless of the number of wheels that meet specific conditions. There is a method of adding values.

The rough road index is generally decremented by a certain number at regular intervals in accordance with the magnitude of the estimated vehicle speed, but is decremented when the vehicle is running on a rough road where detection is continuously performed many times at short time intervals. Since the increment amount exceeds the amount, the index gradually grows and increases, and accordingly, the sensitivity of the decompression judgment gradually decreases.

[Problems to be solved by the invention]

A conventional device of this type is configured to add a rough road index when any one of the detection target wheels satisfies a rough road index addition condition, reflect the result in a pressure reduction determination, and reduce the determination sensitivity. It is. Therefore, when a wrong road is misrecognized as a bad road due to a wheel speed signal waveform disorder due to wheel rotor chipping used for wheel speed detection, eccentricity, etc., or a signal waveform disorder due to intrusion of electromagnetic noise, etc. The bad road index is also added, and in such a case, there is a problem that the determination of the pressure reduction becomes unnecessarily strict and the tendency of the wheel lock becomes deep.

An object of the present invention is to solve such a problem.

[Means for solving the problem]

In order to eliminate the above-mentioned problems, the present invention determines that the vehicle is in an abnormal state if there is no request for addition of the bad road index from the same wheel continuously for a certain period of time or more from the other three wheels. Further, means for stopping the addition of the rough road index during the abnormal state is provided.

[Action]

When the condition for adding the bad road index is satisfied only for one wheel and the other three wheels are not satisfied, it is certain that the wheel speed signal satisfying the addition condition as a probability problem is abnormal. . According to the present invention, since the addition of the rough road index is stopped in this case, the bad road index may erroneously grow due to the wheel rotor speed signal disturbance due to the tooth loss, eccentricity, or mixing of electrical noise of the gear rotor. Is reduced.

Note that the addition condition is satisfied for two wheels due to a rotor failure or the like, and the addition condition is not satisfied for the other two wheels (when monitoring the behavior of two non-driving wheels, one wheel is satisfied, and the other one wheel is not satisfied). (Unsatisfied) cannot be determined indefinitely.However, stopping the addition under the conditions of 2: 2 or 1: 1 may cause the brakes to become loose when the wheels satisfying the addition conditions are actually running on a bad road. Not preferred.

〔Example〕

 FIG. 1 schematically shows an embodiment of the present invention.

As shown, the electronic control unit 1 performs various calculation and determination signals from the wheel speed sensors S ₁ to S ₄ which are provided on each wheel (only S ₁ on behalf here) as an input And outputs a control signal of brake hydraulic pressure to a pressure control valve of the hydraulic system.

AC signal from the wheel speed sensor S ₁ is converted into a pulse, the pulse is converted to the wheel speed is counted by the wheel speed detection means 2. Further, the wheel speed signal is input to the calculation and lock state detecting means 3, where the estimated vehicle speed, the slip speed of each wheel, the wheel deceleration and the like are calculated.

In addition, the addition condition satisfaction determination means 4 includes the wheel speed detection means 2.
, And it is determined whether or not the conditions for adding the bad road index are satisfied for each wheel. Here, when the amount of change in the wheel speed exceeds a certain amplitude a (for example, 1 G acceleration) and a certain frequency b (for example, 62.5 Hz), it is determined that the addition condition is satisfied.

When this addition condition is satisfied, the rough road index calculating means 5 adds the rough road index and sends it to the calculation and lock state detecting means 3.

In this example, the lock state detecting means 3 determines that the wheel lock has started when the calculated slip speed exceeds the threshold value, and issues a pressure reduction command to the solenoid drive circuit 7.
The determination of the pressure reduction at this time is performed by changing the threshold value so that the sensitivity of the determination decreases as the rough road index increases.

The solenoid drive circuit 7 excites the solenoids SOL ₁ and SOL ₂ when receiving the pressure reduction command from the lock state detecting means 3.
As a result, the normally open pressure control valve 12 closes the brake fluid supply path from the hydraulic pressure source including the master cylinder 11 and the accumulator 16, and the normally closed pressure control valve 13 opens the brake fluid discharge path. Therefore, the brake fluid of the wheel cylinder 14 flows to the reservoir 15, and the brake fluid pressure decreases.

On the other hand, when the pressure reduction is started, the motor drive circuit 8 starts the motor M, and the pump P pumps up the liquid in the reservoir 15 and returns the liquid to the supply side.

Further, when the wheel speed starts to recover due to the pressure reduction and the slip speed becomes smaller than a certain value, the lock state detecting means 3 determines that the lock has been avoided and issues a pressure command to the solenoid drive circuit 7. With the demagnetization of SOL ₁ and SOL ₂ by this command, the pressure control valves 12 and 13 return to the state shown in the figure, and re-pressurization is performed. In some cases, during decompression or re-pressurization
SOL ₁ is excited and SOL ₂ is demagnetized to maintain pressure.

In addition, the judgment of the tendency to lock and the tendency to recover from lock
In addition to slip speed and wheel deceleration, it may be performed by adding other indicators.

Next, the configuration of the part that characterizes the present invention will be described.

As shown in FIG.
Is provided. The addition stopping means 6 determines whether the conditions for adding the bad road index are satisfied for all four wheels.
If only one wheel is established and the other three wheels are not established,
The addition by the rough road index calculation means 5 is stopped, and the addition is performed only when the condition is satisfied for two or more wheels.

Such addition stopping means 6 can be implemented as a computer program. FIG. 2 shows an example of a flowchart for such means. FIG. 3 shows the relationship between the wheel speed, the monitoring timer, and the rough road index in the control based on the flowchart.

First, when the control cycle starts, in step 30 ch
The number of (channels) is cleared to zero. Next, at step 31, it is asked whether the conditions for adding the rough road index have been satisfied for the first channel.
If so, the monitoring timer is cleared in step 33 and the process jumps to step 38.

Also, in step 32, it is asked whether the monitoring timer has continued for a predetermined time k _{1 ms} or more, that is, whether the addition condition of the rough road index has continued for a certain time or more.If YES, proceed to step 34, and if NO, monitor in step 35. Increment the timer and jump to step 37.

Next, in step 34, the monitoring timers of the other three wheels are all set to 0.
That is, whether all the addition conditions are not satisfied is determined. If NO, all monitoring timers are returned to 0 in step 36, and the bad road index is added in step 37.

Further, in step 38, it is confirmed whether or not the judgment has been completed for the other three wheels. If NO, the number of channels is counted up by one in step 39, and the process returns to step 31. If the condition of YES is satisfied, the control is terminated. .

According to this control cycle, in the state of part A in FIG. 3 in which only the wheels of the FR satisfy the addition condition, the monitoring timer is started at step 35 in the judgment on the FR at first.
Until k _{1 ms} , the rough road index is once added at the increment of θ ₁ , but after the monitoring timer reaches k _{1 ms, the} control flow changes from step 31 → 32 → 34 and the addition stops, and to become 0 decreases at a constant reduced width of the wake not theta ₄ to the time elapsed summed exponent, it is not affected by false.

Further, in the part B or C of FIG. 3, since two or more wheels satisfy the addition condition, the flow from step 34 is → 36 → 37.
And the bad road index is added.

In this case, the increase amount of the bad road index per wheel is θ _1, and a value obtained by multiplying the increase amount by the number of wheels satisfying the addition condition is added (the decrease amount is always constant). The amount can be constant even if the addition request is from two or more wheels.

FIG. 4 and FIG. 5 show an example of this.

The difference between the flowchart of FIG. 4 and FIG. 2 is that a step 40 is placed after step 36 so that the flag of the rough road index can be set here. The setting state of the rough road index addition flag is confirmed in step 41, and if YES, the process proceeds to step 37 to add the rough road index, and if NO, the control cycle is terminated without passing through step 37. . Needless to say, a step 29 for clearing the bad road index addition flag is also provided before step 30. Even in such a control cycle,
When only one wheel satisfies the addition condition, substantial addition is not performed.

In FIG. 5, as described above, the addition amount of the rough road index is constant irrespective of the number of wheels required to be added.

〔effect〕

As described above, according to the present invention, the means for stopping the addition is provided when the condition for adding the bad road index is satisfied for only one wheel, so that the gear rotor is damaged, the mounting accuracy is poor, or the It is said that the bad road index does not erroneously grow due to the fluctuation of the wheel speed signal due to the mixing of noise and the like, and the problem of the deepening of the tendency to lock due to the erroneous growth is solved and the braking performance of the wheel is improved. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of an example of the apparatus of the present invention, FIG. 2 is a flowchart showing an example of a control cycle of a rough road index, and FIG. 3 is a flowchart of FIG. FIG. 4 is a flowchart showing another example of a control cycle, FIG. 5 is a diagram showing a state of adding a rough road index in the above flow, and FIG. 6 is a diagram showing addition of a rough road index by a conventional device. It is a figure showing a state. 1 ... electronic control device, 2 ... wheel speed detecting means, 3 ...
Calculation and lock state detection means, 4... Addition condition satisfaction determination means, 5... Rough road index calculation means, 6.
7: Solenoid drive circuit, 8: Motor drive circuit, 11
…… Master cylinder, 12, 13 …… Pressure control valve, 14 ……
Wheel cylinder, 15 Reservoir, 16 Accumulator, S Wheel speed sensor, P Pump, SOL
solenoid.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B60T 8/66 B60T 8/96

Claims (1)

(57) [Claims] An apparatus for controlling a brake fluid pressure by performing an arithmetic operation based on a signal from a wheel speed sensor and detecting that the wheel has a tendency to lock or to recover from the lock, comprising: Means for determining the condition of the rough road index addition condition for each wheel based on the amount, and a rough road index calculation means for adding the rough road index with the magnitude obtained from the change amount of the wheel speed when the rough road index addition condition is satisfied. In the wheel speed control device for slowing down the detection sensitivity of the lock tendency in accordance with the magnitude of the rough road index, when the addition of the rough road index is continuously issued from the same wheel for a predetermined time or more, the other three wheels A means for judging an abnormal state if there is no addition request during this period, and stopping the addition of a bad road index during this abnormal state.