JPS63287653A - Anti-lock device - Google Patents

Abstract

PURPOSE:To prevent excessive pressure reduction in the anti-lock device of an automobile by detecting the peak value of deceleration while pressure is being reduced, and outputting a command of temporary holding brake pressure after the maximum deceleration is indicated. CONSTITUTION:As a brake is applied and wheel speed Vw starts to be reduced, a circuit 5 calculates a slip ratio lambda from an estimated body speed Vv and a slip ratio evaluating signal S and, when the slip ratio lambda is above a threshold value lambda1 while deceleration being smaller than a defined value -b without the peak value of the deceleration being appeared, an AND circuit 14 gives an H output. Then, when the peak value is detected, an F/F 12 is set and, as the lambda becomes lower than a threshold restoring value lambda2 a pressure holding signal O11 is turned on whereas, a pressure reducing signal O12 is turned off, via AND circuits 14, 15, an OR circuit 16, and a timer 18. Thereby, any inconvenience that locking gets deeper by carrying out the holding of a temporarily brake pressure too early or, on the contrary, that too much pressure reduction is given to a wheel which was able to be restored from locking, can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an anti-lock device for detecting the locked state of the wheels of an automobile and efficiently applying braking force.

[Conventional technology]

The anti-lock device has a configuration roughly as shown in FIG.

First, the AC voltage supplied from the wheel speed sensor S is converted into pulses by the interface circuit 22, counted by the pulse processing circuit 23, and inputted to the calculation and lock state detection circuit 24 as a wheel speed signal. This circuit 2
In step 4, the estimated vehicle speed, deceleration, or acceleration is calculated based on the wheel speed signal, and by comparison with various threshold values, if the wheels tend to lock, a brake pressure reduction command is issued; Further, when the lock is in a tendency to recover, a pressure increase command is issued.Furthermore, depending on certain conditions, a brake pressure maintenance command may be issued even during a pressure reduction or pressure increase command.

Now, when a pressure reduction command is issued from the circuit 24, the solenoid drive circuit 25 excites the solenoid SQL+ and the solenoid 5OLz. Then, pressure control valves ■1 and ■2
both move to the right in the figure, control valve v1 cuts off the hydraulic circuit from the hydraulic pressure source consisting of mask cylinder 26 and pump P, and control valve V! connects the hydraulic circuit from the wheel cylinder 27 to the reservoir 28. Therefore, the brake pressure is reduced.

When a pressurization command is issued, the solenoid drive circuit 25
When solenoid SQL and 5OLz are demagnetized,
Pressure control valves (1) and (2) both move to the positions shown in the figure, allowing the hydraulic pressure generation source and the wheel cylinder 27 to communicate with each other.

Also, when a pressure hold command is issued, solenoid S
When energizing QL and demagnetizing solenoid 5OLz,
The control 'B valve ■1 moves to the right in the figure, and the control valve ■2 remains as it is in the figure, so the wheel cylinder 27
It is cut off from the source of hydraulic pressure and its pressure is confined in the wheel cylinder 27 circuit.

Brake pressure is therefore kept constant.

In such an anti-lock device, when a lock tendency is detected and a brake pressure reduction command is issued continuously for a preset first set time or more, a second brake pressure reduction command after the first set time is issued. The decompression command is interrupted for the set time, and
A device is known that is equipped with a control means that generates a command to maintain brake pressure (Japanese Patent Publication No. 59-30588). This is done in order to shorten the braking distance without reducing the brake pressure more than necessary by further reducing the pressure if necessary.

[Problems with conventional technology]

However, if the brake pressure is maintained regardless of the behavior of the wheels after a certain period of time has elapsed after the start of pressure reduction as described above, the pressure may be held too early even though pressure reduction is actually still necessary. The wheels may become locked, or vice versa.
Even if the pressure is maintained earlier, the pressure will not be maintained until after a certain period of time has passed for the wheels that have recovered from the lock, resulting in a problem of excessive pressure reduction.

Therefore, an object of the present invention is to solve the above problem and to prevent excessive pressure reduction and premature pressure holding by appropriately changing the point at which brake pressure starts to be held during brake pressure reduction according to the behavior of the wheels. It lies in trying to avoid sex.

[Means of problem solving]

In order to solve the above problem, in the present invention, after the anti-lock device detects a tendency of the wheels to lock and issues a brake pressure reduction command, the peak of deceleration is detected, and from that point on, for a predetermined period of time, The system now issues a command to maintain brake pressure.

[Effect]

Among wheel behaviors, deceleration indicates the rate of change in wheel speed, so the fact that deceleration has reached its peak indicates that the wheel speed is almost certainly heading toward recovery. Therefore, it is not too early to issue the brake pressure holding command at this time, which is the optimal timing, and is effective in shortening the pressure reduction time.

〔Example〕

As shown in FIGS. 1 and 2, a pulse signal proportional to the rotational speed of the wheel is supplied from a wheel speed detection means 1 including a sensor, an interface circuit, and a pulse processing circuit.
The wheel speed signal v is counted by the wheel speed calculation circuit 2.
Output w. The estimated vehicle speed calculation circuit 3 receives the signal v,1
Then, the estimated vehicle speed vv is calculated. On the other hand, in the slip speed evaluation signal calculation circuit 4, the wheel speed signal V. and the vehicle body speed signal Vv, a slip speed evaluation signal S is calculated, and the circuit 5 calculates these signals V. , VV, and S, the slip speed signal λ (=Vv-S-V.) is calculated and output. Note that although the signal S is obtained by filtering the actual slip speed (Vv Vw), this signal S may not be used.

These signals λ are each supplied to evaluation circuits 6.7 and evaluated using the slip start threshold value λ1 and the slip recovery threshold value λo, respectively, and the results are used as ON/OFF logic signals 0! ,
Output with 03.

The wheel speed signal Vw is supplied to a differentiating circuit 8, and the deceleration of the wheel is calculated. Deceleration signal as calculation result <
The input signal is fed to the deceleration evaluation circuit 9, where the deceleration threshold value is evaluated and the result is output as a logic signal 0. is output as On the other hand, the deceleration signal N is the deceleration peak detection circuit 1
1 and when a peak is detected, the signal 0. , which causes the flip-flop 12 to become cent.

Note that the circuit 11 and the flip-flop 12 are reset by an inverted signal from the inverter 13 of the slip continuation signal O1, which will be described later.

Next, the action during the pressure reduction period will be explained.

Now, the brake is activated and the wheel speed signal is V. begins to decrease, circuit 3 generates a predetermined estimated vehicle speed signal VV. Circuit 4 receives these signals Vv and Vw and calculates a slip speed evaluation signal S, and circuit 5 generates a slip speed signal S. Calculate λ.

When this signal λ exceeds a certain value λ1, the circuit 6 turns on the signal 02. Further, the deceleration signal, which is the differential value of the wheel speed signal V@, is evaluated in the circuit 9 and is given a constant value -
When it becomes smaller than b, the signal o1 is turned on. On the other hand, since the peak of deceleration has not yet appeared, signal 04 remains off, and therefore signal Os also remains off. Therefore, the output signal Oh of the AND gate 14 is turned on, but when the peak Dpaak of deceleration is detected, the peak value detection signal 0
4 is turned on, flip-flop 12 is activated,
Signal 0. turns on, and the output signal of AND gate 14 becomes 0.
．． is turned off.

The output signal of the flip-flop 12 is input to an AND gate 15, and the output of the circuit 7 is connected to the negative terminal of the AND gate 15. Right now, the signal is 0. is on, and the slip speed signal λ is not below the slip recovery threshold λ, so the output signal Os of the evaluation circuit 7 is off.

Therefore, the output signal of AND gate 15 is 0. Turns on.

Since the output signals 0& and 0° of the AND gates 14 and 15 are input to the OR gate 16, when the signal 0 is on and the signal O9 is off, the output signal of the OR gate 16, that is, the slip continuation signal 0. is on, and after the signal 06 is turned off, the signal O1 is turned on, so the slip continuation signal 0. is still on. Thereafter, the signal 0.1 is turned off because the output signal O3 of the evaluation circuit 7 is turned on, and the signal 0.1 is turned off. is turned off, that is, when the value of the slip speed signal λ falls below the slip recovery threshold λ2.

The output signal of the flip-flop is 0. is and gate 1
9 and is also input to the on-delay timer 18. This timer 18 receives a signal 0.0 which is turned on after a set time TI after the signal O2 remains on. Outputs 0. As soon as the signal is turned off, the signal 0. is off. Therefore the signal O
After the output signal 0.3 of the on-delay timer 18 is turned on, the output signal 0. remains off. Since this signal O9 is input to the negative terminal of the AND gate 19, the output signal of the AND gate 19, that is, the pressure holding signal 01. is turned on. On the other hand, since the signal O1° is input to the negative terminal of the AND gate 17, the pressure reduction signal 0□ is turned off. This state continues for T1 time.

When the time TI elapses, the output signal 0 of the timer 18 is turned on, and therefore the output signal O1 of the AND gate 19 is turned off. Therefore, the output signal O1 of the AND gate 17 is turned on again. Note that when the signal O is turned off within 11 hours, both the signals 01 and Olt are turned off. This indicates the pressurization mode, which is not shown in FIG.

In this embodiment, the pressure reduction signal 0. As a condition for turning on □, thresholds were set for both deceleration and slip speed, and only when the AND of these was satisfied, but the present invention is not limited to this. Either deceleration or slip speed may be used.

Furthermore, the circuits shown in the embodiments can be configured with hardware, or can be provided with the same functions using software built into a microcomputer.

〔effect〕

According to the present invention, as described above, by detecting the peak of deceleration during decompression, temporary braking is performed after the maximum deceleration, which is a clear indicator that the lock is likely to recover in the future, is detected. Since a command to hold the pressure is issued, there is an advantage that if the lock is held too early and the lock deepens, or conversely, even if the wheel is held too early, the wheel that has recovered from the lock will not have the problem of being depressurized too much. be.

[Brief explanation of drawings]

FIG. 1 is a schematic circuit diagram of the anti-lock ULF of the present invention,
FIG. 2 is an operating diagram similar to the above, and FIG. 3 is a block diagram showing an outline of the anti-lock device. 1... Wheel speed detection means, 2... Wheel speed calculation circuit, 3... Estimated vehicle body speed calculation circuit,
6.7...Slip speed evaluation circuit, 8...
...Differential circuit, 9... Deceleration evaluation circuit, 11.
... Deceleration peak verification circuit, 12 ... Flip-flop, 14.15 ... AND gate, 18 ... On-delay timer, 17.19 ...
. . . AND gate, 24 . . . Calculation and lock state detection circuit.

Claims (1)

[Claims] It performs calculations based on the wheel speed signal supplied from the wheel speed detection means, and when it detects that the wheels tend to lock, it issues a command to reduce the brake pressure, and when the lock tends to recover, it issues a command to increase the brake pressure. , and calculation and lock state detection means for issuing a brake pressure holding command as necessary, and means for opening and closing a pressure control valve of the brake hydraulic circuit based on the pressure reduction, pressurization, and holding commands. In the anti-lock device, the calculation and lock state detection means detects a lock tendency and issues a command to reduce the brake pressure, then detects the peak of deceleration, and issues a command to maintain the brake pressure for a predetermined period of time from that time. An anti-lock device characterized in that it has a control means configured to emit.