JPH032105B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an anti-skid device for automobile brakes.

BACKGROUND TECHNOLOGY In automobiles, if the braking force is excessive, the tires may become locked, and as the tires slide on the road surface without rotating, the braking force decreases from its maximum value. This can cause problems such as inability to steer due to only the front wheels locking up, and irregular turns due to the rear wheels locking up, so when the braking force is too large and the wheels are about to lock up, the braking force is temporarily reduced.
As a result, a so-called anti-lock device is widely used which returns the braking force to the previous level once the condition in which the wheels are likely to lock is resolved.

It is desirable for an anti-lock device to perform anti-lock control independently for each wheel, but due to weight and cost constraints, for a pair of left and right front wheels, one of the left and right wheels is already in a locked state or is in a locked state. The so-called high-select type anti-lock control is used to apply anti-lock control to both left and right wheels only when the other one subsequently becomes locked. On the other hand, an anti-lock control device using so-called row select type control has already been developed, which immediately performs anti-lock control on the left and right wheels when a lock occurs (for example, see Japanese Patent Laid-Open No. 58-450). ).

Problems to be Solved by the Invention The braking system of an automobile has two systems so that even if a part of the braking system fails, the braking function of the entire braking system will not be impaired due to the failure. A two-system control system is widely used in which each system performs a braking function independently. When trying to apply the above-mentioned front wheel high select type and rear wheel low select type anti-lock control to the cross-piped two-system control control device that is often used in front-wheel drive vehicles with a large front wheel load, it is necessary to apply the cross-piped two-system hydraulic control system. In addition to the circuit, left and right front wheels and left and right rear wheels type 2
There are problems such as the need for a system hydraulic circuit.

It is an object of the present invention to solve these problems and to improve braking performance when driving on rough roads.

Means for Solving the Problems The present invention provides a cross-piped braking system for automobiles that supplies braking fluid pressure from a master cylinder to the brakes of front and rear wheels on a diagonal line. A wheel speed sensor that emits a wheel speed signal is provided, and the higher wheel speed signal is selected from among the wheel speed signals emitted by the wheel speed sensors installed on the left and right front wheels, and the high select circuit outputs the wheel speed signal and the right wheel speed signal. A first row select circuit that generates an anti-lock signal when the slip rate of either the wheel speed signal or the vehicle speed signal generated by the wheel speed sensor provided at the rear wheel exceeds a preset reference value. A left front wheel-right rear wheel brake fluid pressure control device is provided which reduces the brake fluid pressure of a cross piping system including a left front wheel and a right rear wheel by a predetermined value in response to an anti-lock signal, and also includes a wheel speed signal of the high select circuit. A second row select circuit generates an anti-lock signal when the slip rate with respect to either the wheel speed signal generated by the wheel speed sensor provided on the left rear wheel or the vehicle body speed signal exceeds a preset reference value. The present invention is characterized by the provision of a right front wheel-left rear wheel brake hydraulic pressure control device that reduces the brake hydraulic pressure of a cross piping system including a right front wheel and a left rear wheel by a predetermined value in response to the anti-lock signal.

By adopting the above configuration, the present invention employs a high selection method for the left and right front wheels when the left and right wheels contact a road surface with different coefficients of friction. The front wheels lock, but the anti-skid operation (same as anti-lock operation), which is performed by lowering the brake fluid pressure in the piping system, does not operate until just before the rear wheels on the road side, which have a high coefficient of friction, lock.

On the other hand, in other systems, the rear wheels on the road side, which have a low coefficient of friction, tend to lock before the front wheels on the road side, which have a high coefficient of friction, so by adopting a low select circuit, the braking of that piping system is An anti-skid operation is performed by lowering the hydraulic pressure, which prevents both the front and rear wheels from locking.

As a result, when the left and right wheels touch a road surface with different coefficients of friction, the front wheel on the road side with a low coefficient of friction locks, but the other three wheels do not lock, and the front wheel on the road side with a high coefficient of friction locks. The rear wheels can utilize their braking power to the limit of locking.

Example The present invention will be explained with reference to the accompanying drawings.

In FIG. 1, 1 is a brake pedal, and 2 is a master cylinder. When the brake pedal 1 is depressed, the master cylinder 2 is actuated, and two systems of braking hydraulic pressure piping 31, 32 are connected to the left front wheel 5, the right rear wheel 6, and the right front wheel. Braking fluid is force-fed to each wheel cylinder of the wheels 4 and left rear wheel 7 to brake all the wheels.

In the above-mentioned cross-piped brake system, as shown in FIG.
A right front wheel speed sensor 41, a left front wheel speed sensor 51, a right rear wheel speed sensor 61, and a left rear wheel speed sensor 71 are provided for each of the two wheels to detect wheel rotation and issue a wheel speed signal. Either one of the wheel speed signal of the high select circuit 81 which selects the higher wheel speed signal among the wheel speed signals emitted by the wheel speed sensor 51 and outputs it as an output, or the wheel speed signal emitted by the right rear wheel speed sensor 61. The brake fluid pressure including the left front wheel 5 and right rear wheel 6 is determined by the anti-lock signal of the first row select circuit 82 which issues an anti-lock signal when the slip rate relative to the vehicle speed signal exceeds a preset reference value. The left front wheel-right rear wheel brake fluid pressure control device 91 provided in the pipe 31 is activated to reduce the brake fluid pressure by a predetermined value, and the wheel speed signal output from the high select circuit 81 and the left rear wheel speed sensor 71 are activated. The anti-lock signal of the second row select circuit 83, which generates an anti-lock signal when the slip rate for either one of the vehicle body speed signals and the wheel speed signal that is generated exceeds a preset reference value, is used to control the right front wheel 4. Left rear wheel 7
The right front wheel provided in the brake hydraulic pressure piping 32 including
The left rear wheel brake hydraulic pressure control device 92 is operated to reduce the brake hydraulic pressure by a predetermined value.

8 is the high select circuit 81, the first low select circuit 82, and the second low select circuit 83.
A control circuit 10 is a vehicle speed sensor that detects the vehicle speed and issues a vehicle speed signal.

In the above, as shown in Fig. 3, the right front and rear wheels of the car run on a low friction coefficient road surface such as an icy road.
Considering a situation in which the left front and rear wheels are running on a road surface with a high friction coefficient such as an ordinary paved road, the right front wheel 4, which is on a road surface with a low friction coefficient, is driven as shown by the hatched wheel in Fig. 3. Since the wheel locks up or is on the verge of locking up during braking, the wheel speed becomes lower than that of the left front wheel 5, which is on a road surface with a high friction coefficient. Since the right front wheel speed sensor 41 and the left front wheel speed sensor 51 are connected to the high select circuit 81, the high select circuit 81 is connected to the left front wheel speed sensor 51 provided on the left front wheel 5, which has a high wheel speed due to the above-mentioned reason. The output is a wheel speed signal.

When the wheel speed signal generated by the high select circuit 81 is input to the second low select circuit 83 together with the wheel speed signal from the left rear wheel speed sensor 71 provided on the left rear wheel 7, the second low select circuit 83 The select circuit 83 selects the lower one of both inputs,
The slip rate ( _λ
= 1 - V _w /V) exceeds a reference value (for example, about 10%), an anti-lock signal is generated, and the brake hydraulic pressure piping 32 including the front right wheel 4 and the rear left wheel 7 is connected to the anti-lock signal. The front right wheel/rear left wheel brake hydraulic pressure control device 92 is operated to reduce the brake hydraulic pressure by a predetermined amount to perform anti-lock operation.

That is, the right front wheel-left rear wheel braking hydraulic pressure control device 92 is controlled by the left front wheel speed sensor 51 and the left rear wheel speed sensor 71 provided on the left front wheel 5 and the left rear wheel 7, both of which are on a high friction coefficient road surface. Antilock operation is not performed until any one of the wheel speed signals exceeds the slip rate reference value.

On the other hand, the left front wheel-right rear wheel braking hydraulic pressure control device 91 is connected to a left front wheel speed sensor 51 provided on the left front wheel 5 which is on a high friction coefficient road surface and a right rear wheel 6 which is on a low friction coefficient road surface. Wheel speed sensor 61
Anti-lock operation will not be performed until one of the wheel speed signals from Since it is in the state, the first row select circuit 8
2, an anti-lock signal is issued, and the anti-lock signal activates the left front wheel-right rear wheel brake hydraulic pressure control device 91 interposed in the brake hydraulic pressure piping 31 including the left front wheel 5 and the right rear wheel 6, Anti-lock operation is performed by reducing the brake fluid pressure by a predetermined amount. As a result, when the wheel is no longer locked or is about to lock, the brake fluid pressure is returned to the previous level.

To summarize the above, the wheel speed signal from the left front wheel speed sensor 51 provided on the left front wheel 5 on the high friction coefficient road surface obtained by the high select circuit 81 and the left rear wheel 7 on the high friction coefficient road surface The anti-lock operation by the right front wheel-left rear wheel braking hydraulic pressure control device 92 is performed until the slip rate for either vehicle body speed exceeds the reference value with respect to the wheel speed signal from the left rear wheel speed sensor 71 provided at the front left wheel. Therefore, even if the right front wheel 4 is locked, the left rear wheel 7
The braking force will not become small, and the wheel speed signal from the left front wheel speed sensor 51 and the wheel speed from the right rear wheel speed sensor 61 provided on the right rear wheel 6 on the low friction coefficient road surface. Anti-lock operation by the left front wheel-right rear wheel braking hydraulic pressure control device 91 is not performed unless the slip rate for either vehicle speed with respect to the traffic light exceeds a reference value. Since the right rear wheel 6 is locked or close to locking, anti-lock operation is performed immediately, so the right rear wheel 6, which is on a low friction road coefficient surface, can maintain braking force without locking, and the right front wheel 6 is locked. This can be limited to only the wheels 4.

It goes without saying that even if the high friction coefficient road surface and the low friction coefficient road surface are opposite to those shown in FIG. 3, the same results as above can be obtained.

Effects of the Invention By adopting the above configuration, the present invention eliminates the need for separately providing two piping systems for the left and right front wheels and the left and right rear wheels in addition to the cross piping system in an automobile having a cross piping type brake device. , it is possible to perform high select control for the front wheels and low select control for the rear wheels, and when the left and right wheels are on a high friction coefficient road surface and a low friction coefficient road surface, respectively, Since only the front wheel on the ground locks and the other three wheels do not, sufficient braking force can be obtained, and directional stability is ensured by preventing the rear wheels on the low friction coefficient road surface from locking. In addition, the front wheels on a road surface with a high friction coefficient do not lock up, so steering performance can be ensured, and other practical effects can be brought about.

[Brief explanation of the drawing]

Fig. 1 is a control system diagram of the hydraulic system and electrical system showing an embodiment of the present invention, Fig. 2 is a block diagram showing the control mode, and Fig. 3 is when braking a car on a road surface with a different coefficient of friction. It is an explanatory diagram of the behavior in . 1... Brake pedal, 2... Master cylinder, 31, 32... Braking fluid pressure piping, 4, 5, 6,
7...Wheel, 41,51,61,71...Wheel speed sensor, 8...Control circuit, 81...High select circuit, 81,82...Low select circuit, 9
1, 92...Brake fluid pressure control device, 10...Vehicle speed sensor.

Claims (1)

[Claims] 1. In an automotive cross-piped brake system that supplies braking fluid pressure from a master cylinder to the brakes of the front and rear wheels on the diagonal, a wheel speed sensor is installed on each of the four wheels on the front, rear, left, and right sides to detect wheel rotation and issue a wheel speed signal, The wheel speed signal of a high select circuit which selects the higher wheel speed signal among the wheel speed signals emitted by the wheel speed sensors provided on the left and right front wheels and issues it as an output, and the wheel speed signal emitted by the wheel speed sensor provided on the right rear wheel. The anti-lock signal of the first row select circuit that issues an anti-lock signal when the slip rate for either one of the vehicle speed signals exceeds a preset reference value is used to control the left front wheel and the right rear wheel. A left front wheel-right rear wheel brake fluid pressure control device is provided to reduce the brake fluid pressure of a cross piping system including a predetermined value by a predetermined value. When the slip rate for either the wheel speed signal emitted by the wheel speed sensor or the vehicle body speed signal exceeds a preset reference value, the anti-lock signal of the second row select circuit generates an anti-lock signal. A brake fluid pressure control device for an automobile brake system, comprising a right front wheel-left rear wheel brake fluid pressure control device that reduces the brake fluid pressure of a cross piping system including a wheel and a left rear wheel by a predetermined value.