JPS5849416B2 - Anti-slip handshake - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an anti-skid device for a vehicle in which a plurality of wheel axles are arranged close to each other.

In general, the brake friction coefficient fb and side friction coefficient fs between the wheels and the road surface are calculated by the wheel slip rate S (vehicle speed
If the wheel circumferential speed is Vw, then S=(■b-vw)÷vb)
As shown in Figure 1, the brake friction coefficient fb is maximum at around S = 0.2, becomes several tenths of that when S = 1 (wheel stuck), and side friction coefficient fs is maximum at S = 0. It decreases as S increases, and becomes almost 0 when S=1.

Therefore, S = 0. Anti-skid control is performed on the wheels by repeatedly loosening, maintaining, and tightening the brake pressure so that the brake pressure is around 2, and the brake pressure is maintained near the maximum.
It is also optimal to maintain sufficient side force, that is, force to prevent irregular rotation.

In anti-skid devices for regular vehicles with four wheels, the coefficient of friction between the wheels and the road surface differs depending on each wheel, or when the vehicle's center of gravity shifts during braking, it shifts to the front and rear wheels. Since the load changes, it is most preferable in terms of performance to perform anti-skid control independently for each wheel, but this requires a wheel speed detector, control circuit, and brake pressure controller for each wheel, which is uneconomical. I can't escape it.

Therefore, as an economical method, an axis control system has been proposed in which the wheels are controlled on an axis-by-axis basis.

In this axis control method, a wheel speed detector is attached to each wheel, but the average value of the left and right wheel speeds or the lower wheel speed is determined for each axle, and based on this speed, the brake force of both wheels of that wheel is adjusted. In this way, changes in the load on the front and rear wheels due to weight shift during braking can be coped with, and the number of control circuits and brake pressure controllers can be halved.

By the way, when performing anti-skid control on two axles of a vehicle having three or more axles that are close to each other and placed at a short distance, or on the axles of a semi-trailer that has two axles that are close to each other, the two axles are in close proximity to each other. Therefore, since the load movement between these axes caused by the weight movement during braking is small, it is uneconomical to install a wheel speed detector on each wheel and control the axes for each wheel.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an economical anti-skid device for a vehicle that controls wheels of multiple axles arranged at a short distance. However, a wheel speed detector is provided for each of the diagonal wheels of a set of a plurality of wheel axles arranged at a short distance, and the average value or the speed signal on the low speed side of the output signals of these wheel speed detectors is determined. The control circuit generates a brake pressure control signal based on this speed signal, and upon receiving this brake pressure control signal, the brake pressure of each wheel is commonly controlled by a brake pressure controller.

Examples of the present invention will be described below.

In FIG. 2, 1 is a tractor and 2 is a semi-trailer, which are connected by a coupler 3.

And the load of semi-trailer is coupler 3 and semi-trailer 2
It is supported by front wheels 4, 4a1 and rear wheels 5, 5a.

However, as shown in the figure, the front wheels 4, 4a and the rear wheels 5,
5a is very short compared to the distance between the front wheels 4, 4a and the coupler 3. For example, when the distance between the front wheels 4, 4a and the coupler 3 is several meters or more, the distance between the shafts is 1. It is about .2m.

Therefore, the load change due to the shift of the center of gravity that occurs during braking is caused by the load change between the coupler 3 and the front and rear wheels 4. 4a, 5, 5a, and only a fraction of that effect appears between the front wheels 4, 4a and the rear wheels 5, 5a.The effect of this effect is that when the front and rear wheels are controlled with the same brake pressure, The shift of the center of gravity during braking does not lead to insufficient braking force.

Furthermore, since the front and rear wheels are close to each other, the coefficient of friction between the road surface and the wheels is approximately the same for the front wheels 4.4a and the rear wheels 5, 5a.

The anti-skid device will be explained in detail with reference to FIGS. 3 and 4.

The wheels are numbered the same as in FIG. 2, and 4 is the right front wheel, 5 is the right rear wheel, 4a is the left front wheel, and 5a is the left rear wheel.

Reference numeral 6 denotes a brake pressure controller, which is interposed in the middle of the brake service line 7 and exhausts the pressure fluid to the relay valve 8, supplies pressure fluid to the relay valve 8, or shuts off the pressure fluid and controls the input of the relay valve 8. Anti-skid pressure control.

The relay valve 8 supplies pressure fluid according to the output pressure of the brake pressure controller 6 from the pressure vessel 9 to each brake actuator 21a, 2lb of the wheel brake device of each front and rear wheel 4, 4a, 5, 5a.
, 22a, 22b.

Detectors j0 and j11 are for the front wheel 4 and rear wheel 5a, respectively, and generate alternating current outputs at a frequency corresponding to the wheel speed of each wheel.

Reference numeral 12 denotes a control circuit, which includes a converter, a selection circuit, and a control logic circuit to be described later, and calculates the outputs of the respective detectors 10 and 11 to control the brake pressure controller 6 to release, maintain, and charge the brake pressure. send a signal.

In FIG. 4, 13 and 14 are converters that convert the outputs of the respective detectors 1o and ii into DC outputs corresponding to the wheel speeds of the front wheels 4 and rear wheels 5a.

A selection circuit 15 selects the lower of the outputs of the converters 13 and 14 or the average value of both.

Reference numeral 16 denotes a control logic circuit which calculates the output of the selection circuit 15 and generates signals to release, maintain, or apply the brake pressure under certain conditions to prevent the vehicle from skidding.

Reference numeral 17 denotes an electromagnetic solenoid for the brake pressure controller 6, which causes the brake pressure controller 6 to perform operations such as loosening, maintaining, and tightening according to the output signal of the control logic circuit 16.

Each element of the structure described above is known from Japanese Patent Application Laid-Open No. 49-44195, Japanese Patent Publication No. 49-33640, etc., and detailed explanation thereof will be omitted.

In this embodiment configured as described above, the number of wheel speed detectors is only two, and the selection circuit selects the lower speed of the two, or the average wheel speed is used as the control input, so that the control It is economical because the number of logic circuits and brake pressure controllers is one.

In addition, since the brake pressure controller is installed on the relay valve input side, the relay valve can be controlled with a small flow input pressure, making it smaller and lighter than when controlling the high flow operating pressure of the brake actuator. It is economical.

In terms of performance, the wheel speed of the diagonal wheels is detected, but since the front wheels 4, 4a and the rear wheels 5, 5a are close to each other, the brake force changes due to weight transfer. can be almost ignored, and if the front wheels tend to skid before the rear wheels, the change will cause the front wheels to skid.
Conversely, when the rear wheels tend to skid before the front wheels, the change is detected by the detector 11 of the rear wheels 5a, which controls the control circuit 12 and brake pressure controller 6. Since the brake pressure is controlled through the brake, rotation of at least two or more wheels can be ensured.

This also applies when there is a difference in braking force between the left and right wheels, such as when driving on a curve.

As for the loss with respect to the braking distance, as mentioned above, the load shift in the longitudinal direction is small, and the difference in the coefficient of friction between the front and rear wheels and the road surface due to changes in the road surface is also due to the fact that the front and rear wheels are close to each other. The time it takes to pass through a changing road surface is very short and can be ignored from the perspective of braking force.
It has performance equivalent to known axis control.

As explained above, by implementing the present invention,
A more economical anti-skid device for a vehicle can be obtained.

Note that the present invention is not limited to the above-described embodiments, and can be modified in many ways within the scope of its technical concept.

In this embodiment, the wheels whose wheel speeds are detected are the front wheel 4 and the rear wheel 5a.
However, the front wheel 4a and the rear wheel 5 may be used.

In addition, in this example, the application was applied to two axles placed close to the semi-trailer, but the two axles were applied before a vehicle with three axles approached each other.
It may be applied to one axis or two axes that approach each other.

[Brief explanation of drawings]

Fig. 1 is a diagram of changes in the coefficient of friction between the wheels and the road surface depending on the slip rate, Fig. 2 is an overall view of a semi-trailer connected to a tractor, and Fig. 3 is a block diagram of piping and wiring in an embodiment of the present invention. , FIG. 4 is a circuit block diagram of the control device. fb・・・Brake friction coefficient, fs・・・・・・
Side friction coefficient, S...Slip rate, 1...
・Tractor, 2... Trailer, 3...
Coupler, 4, 4a... Front wheel, 5, 5a...
...Rear wheel, 6... Brake pressure controller, 7...
... Brake service line, 8 ... Relay valve, 9゜゜゜ ... Pressure vessel, 10.11 ...
Detector, 12...Control circuit, 13.14...
...Converter, 15...Selection circuit, 16...
...Control logic circuit, 17...Solenoid.

Claims (1)

[Claims] 1. In a vehicle anti-skid device that controls the wheels of a plurality of wheel axles of a vehicle having a plurality of wheel axles arranged at a close distance, the wheel speed control device installed on each of a set of diagonal wheels of the plurality of wheel axles A sensor, a control circuit that calculates the average value or low-speed signal of the output signals of these wheel speed detectors, and sends a brake pressure control signal corresponding to this speed signal, An anti-skid device for a vehicle, comprising: a brake pressure controller that commonly controls the brake pressure of the vehicle.