JPS6124220B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an anti-skid device for a vehicle that controls the braking pressure of the wheels to an optimum value to prevent the wheels from locking when braking the vehicle. For this reason, generally, a wheel speed detector is provided to detect the rotational speed of the wheel, and the deceleration of the wheel is detected based on the output. When the deceleration reaches a reference setting value or higher, the braking pressure is set in advance. The braking pressure is reduced at a predetermined speed, and then when the deceleration becomes less than a reference setting value, the braking pressure is increased at a predetermined speed.This operation is repeated. However, with this method, it is difficult to always obtain the optimum braking pressure for wheel movements that change frequently.

The present invention provides an anti-skid device for a vehicle that eliminates the above-mentioned drawbacks and obtains optimum braking pressure for wheel movement.An embodiment of the present invention shown in FIG. 1 will be described below. explain.

In the figure, 1 is a wheel speed detector that generates a signal with a frequency proportional to the wheel rotation speed, and 2 is an f-v converter that converts the output signal of the wheel speed detector 1 into a DC voltage proportional to the wheel rotation speed. , 3 is a differential circuit whose output generates a voltage corresponding to the deceleration of the wheel. 4 is a comparator that compares the reference voltage of the deceleration reference setter 5 and the output voltage of the differentiating circuit 3, and generates a deceleration signal when the differentiated output voltage, that is, the wheel deceleration is higher than the set deceleration, and the differentiating circuit 3 , forms a brake pressure reduction signal generation circuit together with the deceleration reference setting device 5, and uses the deceleration signal as a brake pressure reduction signal. Further, 6 is a comparator that compares the reference voltage of the acceleration standard setter 7 and the output voltage of the differentiating circuit 3, and generates an acceleration signal when the differentiated output voltage, that is, the wheel acceleration is higher than the set acceleration. Together with the reference setter 7, it forms an acceleration signal generation circuit. Reference numeral 8 denotes a pseudo vehicle speed generation circuit, which is composed of a diode 9, a capacitor 10, a constant current discharge circuit 11, and voltage dividing resistors 12 and 13. 14 is f-v
Comparison of the output voltage of the converter 2 and the output voltage of the pseudo vehicle speed generation circuit 8, and when the output voltage of the fv converter 2 is less than the output voltage of the pseudo vehicle speed generation circuit 8, a slip signal is generated. 15 is a gate circuit which generates an output signal when the acceleration signal from the comparator 6 and the slip signal from the comparator 14 are generated simultaneously. 16 is an amplification circuit for applying the deceleration signal of the comparator 4 to the solenoid valve 19 in the brake pressure control device 18; 17 is an amplification circuit for applying the output signal of the gate circuit 15 to the brake pressure control device 18;
This is an amplification circuit for applying voltage to the solenoid valve 20 inside. The braking pressure control device 18 is installed in a conduit connecting a brake valve that generates braking pressure (not shown) and a brake chamber that applies braking pressure to the wheels, and both the solenoid valves 19 and 20 are energized. When not, the braking pressure of the brake valve is directly transmitted to the brake chamber, and when only the solenoid valve 19 is energized, the braking pressure of the brake chamber is reduced at a predetermined speed, and after the pressure is reduced, the solenoid valve is When the excitation of 19 is cut off, the braking pressure in the brake chamber gradually increases at a predetermined speed.
After the pressure is reduced, when the solenoid valve 20 is energized, the braking pressure in the brake chamber is increased at a predetermined speed.
It is configured to rapidly increase pressure.

Next, the operation of FIG. 1 configured as described above will be explained with reference to the operation explanatory diagram shown in FIG. 2. In FIG. 2, 21 is a diagram showing the vehicle speed, 22 is a diagram showing the wheel speed, and the f-v converter 2 corresponds to the output voltage. 23 is a diagram showing the pseudo vehicle speed and corresponds to the voltage of the capacitor 10 of the pseudo vehicle speed generating circuit 8. 24 is a voltage corresponding to the output voltage of the pseudo vehicle speed generating circuit 8, 25 is a slip signal generated by the comparator 14, and 26 is a diagram showing the deceleration of the wheel, which corresponds to the output voltage of the differentiating circuit 3. 27
28 is a diagram showing the deceleration signal generated by the comparator 4, 28 is the acceleration signal generated by the comparator 6, 29 is the braking pressure generated by the brake valve, and 30 is the braking pressure controlled by the braking pressure control device 18. FIG. 3 is a diagram showing braking pressure applied to a brake chamber. The pseudo vehicle speed generation circuit 8 receives the wheel speed 22 as input,
This is a simulated vehicle speed when the wheel speed 22 is decelerated beyond a predetermined speed, and the wheel speed 2
2 decelerates by -1.0 g (g: gravitational acceleration) or more, a pseudo vehicle body speed 23 is generated that decelerates by -1.0 g, which corresponds to the maximum deceleration of the vehicle body. That is, the capacitor 10 is charged via the diode 9 with the wheel speed voltage which is the output voltage of the f-v converter 2, and when the wheel speed voltage of the f-v converter 2 exceeds the deceleration corresponding to -1.0 g. When decelerating, the charge of the capacitor 10 is discharged by the constant current discharge circuit 1.
1 to discharge at a speed equivalent to -1.0g. Note that the diode 9 is assumed to be an ideal diode for convenience of explanation. The resistors 12 and 13 are voltage dividing resistors selected to have values that do not affect the discharge of the capacitor 10. A comparator 14 compares the wheel speed 22 with a diagram 24 showing the output, and the wheel speed 22 is calculated as a pseudo value. When the slip rate exceeds the slip rate determined by the voltage dividing resistors 12 and 13 with respect to the vehicle speed 23, the comparator 14 generates a slip signal 25. During sudden braking, the braking pressure 29 from the brake valve rapidly increases, causing the wheel speed 22 to decelerate, and a point A where the wheel deceleration 26 generated by the differentiating circuit 3 exceeds the deceleration set by the deceleration reference setting device 5. The comparator 4 generates a deceleration signal 27. The deceleration signal 27 is the amplification circuit 1
After the current is increased in step 6, the solenoid valve 19 in the brake pressure control device 18 is energized. When the electromagnetic valve 19 is energized, the braking pressure in the brake chamber starts to decrease at a predetermined speed. By reducing the braking pressure in the brake chamber, the wheel deceleration 26
deceleration decreases, and at point B when the set deceleration is reached, the deceleration signal is canceled and the excitation of the solenoid valve 19 is also cut off.
The braking pressure in the brake chamber is increased accordingly.

However, due to time delays in the f-v converter 2, differential circuit 3, solenoid valve 19, etc., the braking pressure in the brake chamber may be excessively reduced compared to the reaction force generated between the wheels and the road surface. In this case, the wheel speed 22 is rapidly accelerated toward the vehicle body speed 21. An acceleration signal 28 is generated from the comparator 6 at a point C where the wheel deceleration 26 at this time reaches the set acceleration of the acceleration reference setting device 7 or more. On the other hand, when the wheel speed 22 decelerates to -1.0 g or more as the braking pressure increases, a pseudo vehicle speed 23 occurs. At point D, where the wheel speed 22 decelerates beyond the set slip rate of the pseudo vehicle speed 23, the comparator 14 outputs a slip signal 25.
occurs.

When both the acceleration signal 28 and the slip signal 25 are generated, the solenoid valve 20 is activated by the action of the gate circuit 15.
is excited.

That is, at point C, the solenoid valve 20 is energized and the braking pressure starts to increase rapidly. If the sudden increase in braking pressure continues until point E, where the acceleration signal 28 is released as the braking pressure increases, the braking pressure will be over-decreased due to the delay in the system described above, resulting in sudden wheel deceleration and control. Since the slip rate of the middle wheel speed 22 relative to the vehicle body speed 21 increases, and there is a risk that the side force cannot be maintained sufficiently, the sudden increase in braking pressure is stopped at point F where the slip signal 25 is released.

Stopping the sudden application of braking pressure using the slip signal 25 has the advantage that sudden deceleration of the wheels due to sudden application of pressure can be prevented and that the braking pressure can be gradually increased around the appropriate pressure.

After that, the braking pressure is gradually increased, and by repeating the above operation, the braking pressure is controlled to an appropriate pressure so that the wheel speed 22 is decelerated to a slip ratio of around 20% with respect to the vehicle speed 21. becomes possible.

Note that when there is little over-decrease in the braking pressure and the wheel acceleration signal 28 is not generated, the solenoid valve 20 is not excited and the braking pressure can be gradually increased to around the appropriate pressure.

As explained above, the present invention uses means for increasing the controlled braking pressure at two different pressurization speeds, and when the wheel deceleration signal and the wheel slip signal occur simultaneously after the braking pressure has been reduced, the braking By rapidly increasing the pressure and gradually increasing the pressure when no deceleration signal or slip signal is occurring, there is an advantage that the braking pressure can be maintained optimally under various conditions. Note that it is also possible to use the brake pressure rapid pressurization means according to the present invention in combination with brake pressure rapid pressurization means using other methods.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a diagram for explaining the operation of FIG. In the figure, 1 is a wheel speed detector, 2 is an f-v converter,
3 is a differentiation circuit, 4, 6, 14 are comparators, 8 is a pseudo vehicle speed generation circuit, 15 is a gate circuit, 16, 1
7 is an amplifying circuit, and 18 is a braking pressure control device.

Claims (1)

[Claims] 1. A wheel speed detector that detects the rotational speed of the wheels;
A brake pressure reduction signal generation circuit detects wheel deceleration by the wheel speed detector and generates a brake pressure reduction signal when the deceleration exceeds a reference setting value, and the wheel speed detector detects wheel acceleration. An acceleration signal generation circuit generates an acceleration signal when the acceleration exceeds a reference setting value, and uses the output of the wheel speed detector as input, and generates a pseudo vehicle speed when the wheel speed decelerates above a predetermined speed. a slip signal generating circuit that compares the pseudo vehicle speed with the wheel speed and generates a slip signal when the wheel speed decelerates to a reference value or more with respect to the pseudo vehicle speed; and the brake pressure reduction signal. means for reducing the braking pressure of the braking device that brakes the wheels by means of the braking device; means for gradually restoring the braking pressure of the braking device when the braking pressure reduction signal disappears; and the acceleration signal and the slip. 1. An anti-skid device for a vehicle, comprising a brake pressure control device comprising means for rapidly restoring brake pressure when signals are generated simultaneously.