JPS6052014B2 - anti-skid device for vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an anti-skid device for a vehicle that prevents wheels from locking.

This type of anti-skid device detects the rotational speed of the wheel with a wheel speed sensor, calculates the acceleration/deceleration of the wheel from the rotational speed, and when the deceleration of the wheel exceeds a predetermined deceleration reference value, the wheel skids. When the brake pressure supplied to the brake device of that wheel is determined to be reduced and the deceleration of the wheel decreases, and the value becomes smaller than the deceleration reference value mentioned above, the slip ratio of the wheel reaches a predetermined value. The brake pressure is gradually lowered as long as the acceleration reference value has not been reached, and when the wheel acceleration exceeds the acceleration reference value, the brake pressure is kept constant or slowly increased.

By the way, in conventional anti-skid devices, when the acceleration of the wheels exceeds the above acceleration reference value, the brake pressure is kept constant or increases at a constant speed.
If the brake pressure drops too much during the brake pressure reduction process and the wheels suddenly change from deceleration to acceleration, the brake pressure will be suppressed more than necessary. If the brake pressure increases when the vehicle starts accelerating, there is a drawback that the slip ratio, which drops again before the wheel speed fully recovers to the vehicle body speed, increases. The present invention has been made in order to improve the above-mentioned drawbacks, and is directed to the time required from when the deceleration of the wheel becomes smaller than a predetermined deceleration reference value until the acceleration of the wheel becomes equal to or higher than the predetermined acceleration reference value. Provided is an anti-skid device for a vehicle that measures the brake pressure and controls the rate of increase in brake pressure according to the time while the wheel acceleration is equal to or higher than an acceleration reference value, thereby optimally controlling the brake pressure of the wheels. The purpose is to below,
Specific embodiments of the present invention will be described with reference to the drawings.

In FIG. 1 showing a block diagram of an embodiment, a wheel speed sensor 1 is mounted, for example, on a rotating portion of a wheel, and generates a pulse signal with a frequency proportional to the rotational speed of the wheel.

This pulse signal is transmitted to the wheel speed signal generator 2,
It is converted into an analog or digital wheel speed signal V proportional to the wheel speed.

Approximate vehicle speed signal generator 3 receives wheel speed signal V, and until the rate of decrease in wheel speed signal V reaches a predetermined value,
An approximate vehicle speed signal E is generated which maintains the same value as the wheel speed signal (3) and decreases by a preset rate of decrease when the rate of decrease exceeds a predetermined value.

This approximate vehicle speed signal E is compared with the wheel speed signal V by a slip ratio comparator 4, and when the wheel speed signal V becomes a predetermined percentage of the approximate vehicle speed signal E, for example, 90% or less,
The output signal input of the comparator 4, which generates the slip rate signal, becomes RH. The wheel speed signal ■ is also the differentiator 5
The differentiator 5 outputs an acceleration/deceleration signal proportional to the acceleration/deceleration of the wheel. This acceleration speed signal is compared with a predetermined reference value by the deceleration comparator 6, and when the deceleration of the wheel exceeds the predetermined deceleration reference value, a deceleration signal is generated, that is, the output signal of the comparator 6 -b force HJ
become. Further, the acceleration/deceleration signal ~ is compared with a predetermined reference value by the acceleration comparator 7, and when the acceleration of the wheel exceeds the predetermined acceleration reference value, for example 0.5 g, an acceleration signal is generated, that is, the output signal +b is Become a RHJ. The off delay timer 8 receives the output signals of the comparators 6 and 7 via the OR gate 9, and maintains the RH signal for a predetermined time T1, for example, 0.3 seconds after the output signal of the OR gate 9 becomes RL. The pulse signal generator 10 receives the output signal A of the AND gate 11, and when the output signal A of the AND gate 11 becomes H, the pulse signal generator 10 outputs RL. J. A pulse signal having a predetermined time ratio of T2:T3 with respect to l5rH is generated at output terminal B. The flip-flop 12 has its set terminal S connected to the output terminal of the comparator 6, and its reset terminal R connected to the output terminal of the comparator 6. When the output signal -b of the comparator 6 becomes RHJ, the output of the comparator 7 The output signal Q is kept in the RHJ state until the signal +b reaches 1HJ. Further, the flip-flop 13 has its set terminal S connected to the output terminal of the comparator 6, its reset terminal R connected to the output terminal of the comparator 7 via the on-delay timer 14, and its output signal Q is connected to the output terminal of the comparator 6. When the signal of device 6 - B75 becomes HJ, it becomes RH.
When the ΔT time set by the delay timer 14 elapses after the output signal +b of the comparator 7 reaches RHJ, RL! become. The on-delay timer 14 is provided to prevent the up counter 15 from being reset before the presettable down counter 19 (described later) is preset, and its set time ΔT is set to a small value. Up counter 15 receives clock pulse signal FO from pulse oscillator 17 via AND gate 16,
The signal of the reset terminal R connected to the AND gate 18 is R
L. When it reaches j, clock pulses FO are counted until it changes to 1HJ. Then, the output signal F of the AND gate 18 is RLJ from when the output signal -b of the comparator 6 becomes RLyo until the output signal of the comparator 7 becomes RHyo. Therefore, the count value Qi of the up counter 15 is proportional to the time from when the deceleration signal disappears until the acceleration signal is generated. Note that the AND gate 16 is cut off when the count value Qi of the up counter 15 reaches a predetermined value, and prevents the clock pulse FO from being transmitted to the terminal C of the up counter 15.

The count value Qi of the up counter 15 is transmitted to the presettable down counter 19.

The down counter 19 detects that the output signal 1b of the comparator 7 is RH.
When the signal is transmitted to the PR terminal, the count value Qi transmitted from the up counter 15 is set as an initial value, and the clock pulse FO from the pulse oscillator 17 transmitted via the AND gate 20 is counted down. .

Then, each time the count value reaches 0, a short pulse is generated. This pulse signal is transmitted to the mono-multivibrator 21 and converted into a pulse signal having a predetermined pulse width T4. Therefore, the output signal G of the mono-multivibrator 21 generates a pulse signal having a predetermined time width T4 every time the count value of the down counter 19 reaches O. 22 and 32 represent OR gates, and 23, 24, 25, 26 and 27 represent AND gates.

In the current amplifier 28, the output signal of the AND gate 23 is RH.
When reaching J, solenoid 2 of the discharge valve (not shown)
A current ■a is supplied to the terminal 9. Further, when the output signal of the OR gate 32 becomes RH, the current amplifier 30 supplies the current 1e to the solenoid 31 of the cutoff valve (not shown).
Note that the cutoff valve and the discharge valve have a known structure, and are interposed in the piping connecting the master cylinder and the brake device of the wheels, and a current of 1 is applied to the solenoid 31 of the cutoff valve.
When e is supplied, the isolation valve operates to cut off the communication between the master cylinder and the brake device, and the brake pressure of the brake device is maintained constant, and the current 1e is applied to the solenoids 31 and 29 of the isolation valve and the discharge valve. When 1a and 1a are supplied, the braking device is connected via a discharge valve to, for example, a reservoir, and the braking pressure of the braking device is reduced.

Next, the operation of the embodiment will be explained with reference to FIG. 2, which shows an operation diagram. When the brake pedal is depressed to apply the brakes to the vehicle and the brake pressure P increases, the brakes are applied to the wheels and the wheel speed signal (■) decreases.

Then, at time t1, when the deceleration of the wheels exceeds a predetermined deceleration reference value, the output signal -b of the comparator 6 changes to RHJ.
become. Then, this RH signal is transmitted to the OR gate 22, the output signal of the OR gate 22 becomes RH, and the output signal of the AND gate 23 becomes RHJ. Further, the output signal of the OR gate 32 becomes 1H. Therefore, the currents 1e and 1a are supplied to the solenoids 31 and 29 of the isolation valve and the discharge valve, the isolation valve and the discharge valve are activated, and the brake pressure P starts to decrease.

At the same time, the RHJ signal is transmitted to the set terminals S of the flip-flops 12 and 13, and the respective output signals Q become RH. Then, the brake pressure P decreases,
When the wheel deceleration becomes smaller than a predetermined deceleration reference value,
The output signal -b of the deceleration comparator 6 becomes RLJ.

Therefore, the output signal F of the AND gate 18 is RLJ
, and the up counter 15 starts counting the clock pulses FO of the pulse oscillator 17. At this time, the wheel speed signal V is smaller than the predetermined ratio η:E of the approximate vehicle speed signal E, and the output signal λ of the slip ratio comparator 4 is RHJ.
It's getting old. Therefore, since the slip rate signal λ is RHJ, the AND gate 23 and the OR gate 32 operate at RH
The brake pressure P continues to decrease.

As the brake pressure P decreases, the wheels start accelerating, and the time is up!
When the acceleration of the wheel exceeds a predetermined acceleration reference value, the output signal +b of the acceleration comparator 7 becomes RH.

Then, the output signal of the AND game 23 becomes RL, the current 1a to the solenoid 29 becomes zero, and the discharge valve returns to the non-operating position. At the same time, the down counter 19 detects when an acceleration signal is generated, that is, when the output signal of the comparator 7
Count value Qi of up counter 15 when becomes RHJ
Start counting down using the initial value. Then, at time, when the count value of the down counter 19 becomes 0, a pulse with a predetermined time width T4 is transmitted to the mono multivibrator 2.
1 output signal G is generated, inverted by the AND gate 27, and transmitted to the OR gate 32. Therefore, the shutoff valve is
"Deceleration" signal disappears, that is, the output signal of comparator 6 -b
Demagnetization is repeated for a predetermined time period T4, with the period from when the output signal +b of the comparator 7 reaches RLJ until the acceleration signal is generated, that is, until the output signal +b of the comparator 7 reaches RHJ. In other words, the brake pressure P increases stepwise at intervals of a period of time from when the deceleration signal disappears until the acceleration signal is generated.

Therefore, the shorter the above-mentioned time is, the faster the brake pressure increases.

At time ζ, when the wheel acceleration becomes smaller than the predetermined acceleration reference value, the output signal +b of the acceleration comparator 7 becomes R again.
Become LJ.

At this time, since the wheel speed signal V has become larger than a predetermined ratio of the approximate vehicle body speed signal E and the output signal λ of the slip ratio comparator 4 has become RLJ, the output terminal A of the AND gate 11 has a delay The action of timer 8 generates the RH signal. Therefore, the pulse signal generator 10 is activated and a pulse signal with a time ratio T2:T3 is generated at its output terminal B.

This signal is transmitted to the current amplifier 30 via the AND gate 25 and the OR gate 32, and the solenoid 3 of the shutoff valve
1 is intermittently demagnetized. That is, according to predetermined T2 and T3 times, the shutoff valve is closed and opened, and the brake pressure is increased stepwise. Due to the stepwise increase in brake pressure P, the deceleration of the wheels increases again, and at time N5, when the deceleration exceeds the predetermined deceleration reference value and the output signal 1b of the deceleration comparator 6 becomes RHJ again, the AND gate 12 Then, the output signal of the OR gate 32 becomes RHJ, the solenoids 31 and 29 of the cutoff valve and the discharge valve are energized, and the brake pressure P starts to decrease.

When the deceleration of the wheels becomes smaller than a predetermined reference value at time T6 due to a decrease in the brake pressure P, the output signal -b of the deceleration comparator 6 becomes RLJ.

At this time, since the output signal λ of the slip ratio comparator 4 is 1LJ, the output signal A of the AND gate 11 becomes RH.
Then, the pulse signal generator 10 is activated, and the pulse signal is transmitted to the output signal C of the flip-flop 12 when the output signal C becomes RH. Since the current is J, the current is transmitted to the amplifier 28 via the AND gate 26, OR gate 22, and AND gate 23, and intermittently excites the solenoid 29 of the discharge valve.

Note that the output signal of the OR gate 32 is the output signal of the AND gate 11.
The output signal of the flip-flop 12 is RHJ, and the output signal of the flip-flop 12
Since the output signal of is RH, it is held at RHJ via the AND gate 24, so it remains RH. Therefore, the solenoid 31 of the shutoff valve is kept in an energized state.
Therefore, the brake pressure P decreases in stages according to the pulse signal from the pulse signal transmitter 10.

Due to the gradual decrease in brake pressure, at a certain point in time, the wheels tend to recover and the acceleration of the wheels exceeds a predetermined acceleration reference value, and when the output signal of the acceleration comparator 7 becomes +b and HJ, the output signal of the AND gate 23 becomes RLJ, the solenoid 29 is demagnetized, and the discharge valve becomes inactive. At the same time, the down counter 19 starts counting down.

However, the preset value of the down counter 19 is equal to the count value of the up counter 15 counted from the time when the deceleration signal disappears until the acceleration signal is generated, so it is sufficiently large and the count value of the down counter 19 is It takes a long time for it to reach 0. Therefore, during that time, the output signal of the mono-multivibrator 21 is kept at RLJ, and therefore the output signal of the AND gate 27 is kept at 1HJ, and the solenoid 31 of the cutoff valve is kept in an energized state. Then, at time T8 before the count value of the down counter 19 reaches O, when the acceleration signal disappears, that is, when the output signal +b of the comparator 7 becomes RL, the down counter 19 stops counting and the AND gate 11 output signal A is RH
Become J.

Then, the pulse signal generator 10 is activated again, this pulse signal is transmitted to the current amplifier 30 via the AND gate 25 and the OR gate 32, and the solenoid 31 of the cutoff valve is energized according to predetermined times T2 and T3. and disappear repeatedly. That is, the brake pressure P increases step by step.
When the deceleration of the wheels exceeds a predetermined deceleration reference value due to an increase in brake pressure, the above-described series of actions is repeated again to optimally control the brake pressure.

As is clear from the above description, in the present invention, after the deceleration of the wheel recovers to a predetermined deceleration reference value or less and the deceleration signal disappears, the acceleration of the wheel becomes equal to or higher than the predetermined acceleration reference value and the acceleration signal is The system measures the time until the acceleration signal occurs, and increases the brake pressure step by step using a pulse signal with a period corresponding to that time while the acceleration signal is being generated. Wheel acceleration/deceleration
When the change in speed is fast, the pulse signal period is shortened to quickly increase the brake pressure, and when the brake pressure has moderately decreased and wheel acceleration/deceleration changes are gradual, the pulse signal period is lengthened to increase the brake pressure. It has the excellent effect of being able to gradually increase pressure.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an anti-skid device showing one embodiment of the present invention, and FIG. 2 is an operational diagram showing its operation. DESCRIPTION OF SYMBOLS 1...Wheel speed sensor, 2...Wheel speed signal generator, 3...Approximate vehicle speed signal generator, 4...Slip rate comparator, 5...Differentiator, 6...Decrease speed comparator, 7
... Acceleration comparator, 8, 14 ... Delay timer, 10
...Pulse signal oscillator, 12, 13...Flip-flop, 15...Up counter, 19...Down counter, 21...Mono multivibrator, 28
, 30... Current amplifier, 29, 31... Solenoid of discharge valve and cutoff valve.

Claims (1)

[Claims] 1 a deceleration comparator that generates a deceleration signal when the deceleration of the wheel exceeds a predetermined deceleration reference value; an acceleration comparator that generates an acceleration signal when the acceleration of the wheel exceeds the predetermined acceleration reference value; A measuring device that measures the time from when the deceleration signal disappears until the acceleration signal is generated, and a pulse generator that generates a pulse signal with a period corresponding to the measured time, and the acceleration signal is generated. While doing
An anti-skid device for a vehicle that increases brake pressure of the wheel based on the pulse signal.