JPS5851497B2 - Anti-slip handshake - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rear wheel control anti-skid device used in a vehicle anti-skid device which controls the braking force to an optimum value so as to prevent the vehicle from locking during braking.

The purpose of this type of anti-skid device is to reduce the speed of the vehicle to prevent the rear wheels from locking when braking the vehicle, and to prevent irregularities caused by locking the rear wheels due to excessive braking force. The purpose is to prevent

For this reason, a general system detects the rotational speed of the rear wheels, and when the deceleration of the wheels becomes larger than a predetermined setting value, it determines that this is a sign that the wheel force ratio will increase, and the braking force of the wheels is determined. Efforts are being made to reduce the

FIG. 1 is a block diagram of a conventional anti-skid device applied to this type of hydraulic brake system.

In Fig. 1, 1 is a pulse generator that generates pulses proportional to the wheel rotation speed, 2 is an f/V converter that counts the number of pulses of the pulse generator 1 and generates a DC voltage proportional to the wheel rotation speed, and 3 is an f/V converter that generates a DC voltage proportional to the wheel rotation speed. A differentiation circuit that differentiates the output of the f/v converter 2 and generates an output proportional to the acceleration/deceleration of wheel rotation, 4.5 is a comparator, and each has 10G.

It has a comparison value -G, and generates the output when the acceleration/deceleration of wheel rotation exceeds the comparison value.

Reference numeral 6 denotes an output circuit that amplifies the outputs of the comparators 4 and 5 and drives a sudden pressurizing solenoid valve 7 and a pressure reducing solenoid valve 8 built into a braking force release device (not shown).

FIG. 2 is an explanatory diagram of this operation. When the braking torque increases due to the increase in the braking pressure e and exceeds the reaction force due to friction between the road surface and the tires, the wheel speed departs from the vehicle body speed a and begins to lock.

At this time, the wheel speed causes a deceleration exceeding the set value -G of the comparator 5 (Fig. 2 C) The pressure reducing solenoid valve 8 is driven, and the braking pressure e is set at a predetermined speed as shown in Fig. 2. decreases in

Therefore, the braking torque also gradually decreases, the wheel speed gradually approaches the vehicle body speed a, the wheel deceleration becomes -G or less, and the pressure reduction signal is released.

When the pressure reduction signal is released, the braking pressure e gradually increases again at a predetermined speed.

While repeating this operation, the wheel speed is decelerated at an appropriate slip rate relative to the vehicle speed without locking the wheels.

If the braking force is released too much, the wheel speed will generate a large acceleration and a sudden pressure signal will be generated from the comparator 4. This prevents the braking distance from increasing due to excessive rotation.

However, in a device with such a configuration, if the comparison value of the comparator and the rate of increase in braking pressure are set so that it will operate optimally on a dry asphalt road surface where the coefficient of friction between the road surface and the tires is high, for example, the friction coefficient will increase. On low snowy roads or frozen roads, the reaction force from the road surface is small, so the wheels decelerate quickly, making it easier for the wheels to lock up before the vehicle comes to a stop; conversely, it works best on roads with a low coefficient of friction. If each set value is determined so that the wheels rotate too much on a road surface with a high coefficient of friction and a low slip ratio, the braking distance becomes significantly longer.

This invention was made for the purpose of reducing the braking distance from a road surface with a high coefficient of friction to a road surface with a low coefficient of friction without causing the wheels to lock up, and in a manner that reduces or equals the braking distance to that without this device. A vehicle deceleration detection switch is provided to detect vehicle deceleration during braking, and the comparator setting value is switched by the output of the vehicle deceleration detection switch, and the delay in operation of the vehicle deceleration detection switch is compensated for by a sudden pressurizing electromagnetic device. This invention is characterized by the following, and will be explained below with reference to an embodiment of the invention shown in FIG.

In FIG. 3, 9 and 10 are comparators that compare the output voltage of the differentiating circuit 3 with comparison values -〇L, -GH and generate an output when the deceleration of wheel rotation exceeds the comparison values. The comparison value -GL of comparator 9 is set to a value suitable for a road surface with a low coefficient of friction, and the comparison value -GH of comparator 10 is set to a value suitable for a road surface with a high coefficient of friction.

11.12 is an AND gate, 13.14 is an OR gate,
15 is the vehicle body, deceleration detection switch, normal ONL
It turns OFF when the vehicle deceleration exceeds the set deceleration (generally around -0.5G).

One end of the switch is grounded, and the other terminal is connected to a resistor 16.
Connected to power via.

1T is a monostable multi-by-brake, which is triggered the moment the vehicle deceleration detection switch 15 reaches 0FFL, and its time is determined by the decompression signal generation time Ts that occurs first during braking and the -GH signal of the comparator 10 that occurs first during braking. This value corresponds to the time difference between the occurrence times TG.

FIG. 4 is an explanatory diagram of the operation of the actual case shown in FIG. 3. The operation will be explained below with reference to this diagram. When the braking pressure e increases, the wheel speed begins to slip and gradually departs from the vehicle body speed a. Comparators 9 and 10 generate deceleration signals -GL(f), -Gag).

-The GL signal has a deceleration setting value suitable for a decompression signal for a road surface with a low friction coefficient, -The GH multiplication signal has a deceleration setting value suitable for a decompression signal for a road surface with a high friction coefficient, and of course the GL multiplication signal generation time is - It is longer than the GH times signal generation time.

The purpose of the vehicle deceleration detection switch 15 is to detect the vehicle deceleration, and thereby to know the magnitude of the friction coefficient of the braking road surface.The output of the vehicle deceleration detection switch 15 can be used as actual information only for the wheels. This is when the tire slips and the friction between the tire and the road surface is equal to the friction between the tire and the road surface that occurs when the tire locks up. A reed switch is activated using the inertia of a weight, or a mercury switch is used, but these switches generally have a certain amount of delay time relative to the actual deceleration of the vehicle. be.

From these points, on a road surface with a high coefficient of friction, when the first -GL or -GH signal is generated during braking, the vehicle deceleration detection switch 15 is often still ON. , the depressurization signal is applied to the AND gate 11. -GL through OR gate 13
The doubled signal is directly generated as a decompression signal.

On a road surface with a low coefficient of friction, the vehicle body deceleration switch 15 remains ON during braking, and the 10L signal becomes a decompression signal from beginning to end, resulting in optimal operation on a road surface with a low coefficient of friction.

On a road surface with a high coefficient of friction, the braking force will initially be released excessively, but as shown in Figure 4, the vehicle deceleration detection switch 1
5 is 0FFL, the monostable multivibrator 17 is triggered, and a time T corresponding to the difference between the decompression signal generation time Ts that first occurs during braking and the 1GH signal generation time TG that first occurs during braking. During this period, a sudden pressure increase signal is generated, and the braking pressure is suddenly increased through the OR gate 14 to compensate for the delay in the vehicle body deceleration detection switch 15.

This time T is determined by (TS TG'), the rate of decrease in braking pressure, and the rate of sudden increase in brake pressure to a time corresponding to the period outside of excessive depressurization.

After the vehicle body deceleration detection switch 15 is 0FFL and a sudden pressurization signal is generated by the monostable multivibrator 17, -GH
The pressure reduction operation is performed by a signal, and when the wheel speed suddenly decreases during control, a sudden pressure increase signal is issued, as in the past.

If the vehicle deceleration detection switch 15 is turned OFF before the first deceleration signal -〇L is generated during braking, -GH is detected from the beginning.
It is clear that the pressure will only be reduced by the signal.

Additionally, the interval between the first and second pressure reduction signals during braking is generally about 0.3 to 0.4 seconds, and on road surfaces with a high friction coefficient, vehicle deceleration is detected before the second pressure reduction signal is generated. The switch 15 operates, but if the vehicle deceleration detection switch 15 turns OFF before the second depressurization signal is generated,
This is the case when braking is performed on a road surface with an intermediate friction coefficient near the operating limit of the switch.In this case, sudden pressure is applied only outside the initial excessive decompression, but in the case of a road surface with an intermediate friction coefficient, Since the set values of -GL and -GH are determined so that appropriate control can be achieved by depressurizing either of -GI, -GH, sudden pressurization is not necessarily necessary.

In addition, contrary to the embodiment of the present invention, the first pressure reduction during braking is performed by -GH, and thereafter the pressure is reduced by either -GL or -GH corresponding to the G sensor, and there is a delay in the vehicle deceleration detection switch due to pressure reduction. A method of incorporating compensation could be considered, but in this case, when sudden braking is performed on a road surface with a low coefficient of friction, the wheels will fall into deep slip from the beginning.
In the case of a rear-wheel drive vehicle, when the engine stops, it becomes impossible to recover the wheels or control them regularly, and the effect of the compensation circuit is small, so the embodiment shown in FIG. Better actual vehicle results were obtained.

As explained above, this invention uses a circuit consisting of a simple car body deceleration detection switch and a monostable multi-by-brake, etc. When braking, the first decompression signal is a signal suitable for a road surface with a low coefficient of friction, and after that, the car body The deceleration detection switch uses a depressurization signal suitable for the braking road surface, and when braking is performed on a road surface with a high friction coefficient, the braking pressure corresponding to the initial excessive decompression is set to OFF (when the vehicle deceleration detection switch turns 0FF). The system is characterized by compensating for the delay in the operation of the vehicle body deceleration detection switch by applying sudden pressure, so that the wheels do not lock up and the braking distance does not extend from a road surface with a low coefficient of friction to a road surface with a high coefficient of friction. The present invention provides an anti-skid device with a simple structure, which has the advantage of being highly effective in practical use.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional device, FIG. 2 is an explanatory diagram of its operation, and FIG. 3 is a block diagram showing an embodiment of the present invention.
FIG. 4 is an explanatory diagram of its operation. In the figure, 1 is a pulse generator, 2 is an f/v converter, 3 is a differential circuit, 4, 5, 9.8 are comparators, 6 is an output circuit, 7 is a solenoid valve for sudden pressurization, 8 is a solenoid valve for pressure reduction, 1
1 to 13 are gate circuits, 15 is a vehicle deceleration detection switch, and 17 is a monostable multi-vib break. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A wheel rotation speed detector that detects the rotation speed of the wheels; a pressure reduction signal generator that receives the output of the wheel rotation speed detector as an input, detects the deceleration of the wheels, and generates a signal to reduce the braking pressure;
A vehicle deceleration detection switch is provided which turns on and off depending on the magnitude of vehicle deceleration during braking, and the set value of the depressurization signal generator is switched in accordance with the output of the vehicle deceleration detection switch to detect vehicle deceleration. When the braking pressure is excessively reduced due to a delay in the operation of the switch, the brake pressure is suddenly increased temporarily when the vehicle deceleration detection switch is activated, thereby reducing the delay in the operation of the vehicle deceleration detection switch. An anti-skid device for a vehicle characterized by compensation.