JPH028861Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a device that can prevent each of the four wheels from locking when sudden braking is applied, especially when desired.
This invention relates to a device that can release anti-skid brake operation on two front wheels.

When a vehicle brakes suddenly, the direction of travel during braking becomes unstable, especially on roads with a low friction coefficient.
The braking distance tends to increase, and anti-skid brake devices are used to improve this. By the way, vehicles with this anti-skid brake device installed on all four wheels have the advantage of improving braking stability and shortening braking distance, but on special roads such as snow-covered roads or dirt roads, straight-line braking stability is However, the braking distance may be lengthened.
The reason for this is that the frictional relationship between the road surface and the tires is in a region that cannot be explained by theory. Specifically, if the four-wheel anti-skid brake system is not used and the four wheels are locked, snow, dirt, mud, etc. Since the anti-skid brakes are wedged between the wheels and the road surface, it is possible to stop the vehicle in a shorter distance than when braking while keeping the tire slip rate within a certain value.

For this reason, some conventional four-wheel anti-skid brake systems are equipped with a changeover switch for canceling the four-wheel anti-skid brake operation in order to shorten the braking distance on special road surfaces. However, when the changeover switch is turned off, all functions of the anti-skid brake stop, and although braking distance can be shortened, straight-line braking stability cannot be ensured. Moreover,
If you forget to turn the switch back on, the danger increases rapidly on normal road surfaces. If instead of this, the control method for the front wheels is set to select high, that is, the signal of the higher wheel speed is selected among the front wheels, and the control is performed based on that signal, most of the locks will not be applied to the one wheel with the lower wheel speed. Occur. In this case, although the braking distance on special road surfaces is shortened to some extent, it is not preferable because it has an adverse effect on the steering function and the like during braking on normal road surfaces.

The object of the present invention is to provide a four-wheel anti-skid brake device that can ensure straight-line braking stability and shorten braking distance even on special road surfaces.

The four-wheel anti-skid brake system according to the present invention is characterized in that a changeover switch capable of cutting off the output of a detection signal is connected to the front wheel speed detector.

The present invention will be described below with reference to the accompanying drawings.

The four-wheel anti-skid brake system (hereinafter referred to simply as the brake system) shown in FIG. Appropriate braking force is applied based on the detection signals 6, 7, and 8. Each wheel speed detector 5, 6, 7, 8 generates a signal with a frequency proportional to the wheel speed as a detection signal S1, S2, S3, S4. These wheel speed detectors are connected to a control unit 11 by first and second connectors 9,10. Wheel speed detectors 5 for the front two wheels 1 and 2,
Switches 12 and 13, which operate on and off, are connected between the first and second connectors 9 and 10 connected to the connector 6, respectively. These selector switches are knob 1
Switching is performed in conjunction with 4.

The control unit 11 is composed of a microcomputer and an output amplifier connected thereto. This control unit controls each detection signal S.
1, S2, S3, and S4 are A/D converted, and the slip rate of each wheel is detected based on this wheel speed signal and acceleration and deceleration signals obtained by differential processing of this wheel speed signal. The tendency of each wheel to lock is detected from a sudden change, and a close (ON) signal and an open (OFF) signal are output to the electromagnetic valves 15, 16, 17, and 18, respectively, in order to prevent the wheels from locking. The control unit 11 has a brake switch 15 connected to one of its input terminals, which is turned on when the brake pedal is depressed, and is further connected to a power source via a power switch 27 which is interlocked with an ignition switch. The output terminal side of the control unit 11 is connected to the
Three solenoid valves 15, 16, 17, and 18 are connected.

Each solenoid valve is an anti-skid brake modulator (hereinafter simply referred to as a modulator) 1 for each wheel.
These are switching valves 9, 20, 21, and 22, and when they are off, the hydraulic pressure as brake fluid pressure from the master cylinder 29 is directly transferred to each wheel cylinder 2.
3, 24, 25, and 26, and when turned on, it cuts off the connection between the master cylinder and the wheel cylinder, and also acts to loosen the hydraulic pressure on the wheel cylinder side. As each modulator, a well-known negative pressure modulator is used which can ensure a hydraulic loosening operation speed that exceeds the wheel locking speed by utilizing the pressure difference between the engine negative pressure and the atmospheric pressure.

Furthermore, the control unit 11 has an indicator light 30 connected to its output terminal. This indicator lamp outputs a display when the above-mentioned changeover switches 12 and 13 are off.

In such a brake device, the knob 14 is kept on during normal times. Power switch 2
When a sudden brake operation B is performed as shown in FIG. 2 while the vehicle with switch 7 turned on is running on a normal road surface, the control unit 11 detects each wheel speed detector 5, 6, 7, 8. Detection signals S1, S
2, S3, and S4, the locking tendency (a
), each solenoid valve 15, 16, 17, 18
Output to . This allows each modulator 1
9, 20, 21, and 22 adjust the hydraulic pressure to reduce the slip rate of the wheels (section b), prevent locking, and intermittent the braking force applied to the wheels.
Activate anti-skid brakes on 4 wheels.

On the other hand, when the driver enters a snowy road, the driver turns off the knob 14. Then, the indicator light 30 indicates that the front wheel anti-skid brake has been released.
If you suddenly apply the brakes while driving in this condition,
The control unit 11 includes wheel speed detectors 7 and 8.
Based on the detection signals S3 and S4, anti-skid braking is performed on the rear two wheels to apply a sudden brake to the vehicle while preventing them from locking. On the other hand, the control unit 11, which has determined that the rotation of the two front wheels 1 and 2 is zero, follows a mode in which no output is made to the solenoid valves 15 and 16 corresponding to both front wheels. As a result, the two front wheels 1 and 2 that have been subjected to the sudden braking operation become locked. In this case, the rear two wheels 3 and 4 perform anti-skid braking to ensure straight-line braking stability, and the front two wheels, which have a large brake force distribution, generate wheel lock, so there may be snow, etc. between the tires and the road surface. By interposing the wedge-shaped formation, the effect of shortening the braking distance can be increased. This type of operation is effective under special road surface conditions such as snow-covered roads, and the driver can select the changeover switch 12,
This is done by manually turning on and off the 13 knobs 14.

As described above, according to the brake device according to the present invention, when entering a special road surface, the driver first presses the knob 1.
Turn off 4. Then, the control unit's fail-self function activates to release the anti-skid brakes on the front two wheels 1 and 2 when the brakes are applied suddenly, causing the front two wheels to shorten the braking distance, and the rear wheels 3 and 4 to reduce the braking distance. The anti-skid brake can be activated to ensure straight-line braking stability. Therefore, the vehicle can maintain straight-line braking stability even on special road surfaces, and shorten the braking distance. Moreover, even if you overlook the indicator light 30 when returning to the normal road surface, forget to turn on the changeover switches 12 and 13 by returning the knob 14, or even if you make a mistake in the switching position when driving on the normal road surface. , anti-skid brakes are always applied to the rear two wheels. Therefore, straight-line braking stability of the vehicle can always be ensured, and when the switch is turned off, as in the conventional case where an on/off switch A is installed between the control unit and the power supply as shown by the two-dot chain line in Fig. It is possible to eliminate the problem that straight-line braking becomes unstable.

[Brief explanation of the drawing]

FIG. 1 shows a wiring diagram of a brake device as an embodiment of the present invention, and FIG. 2 shows a wheel speed diagram of the same brake device. 1, 2, 3, 4...wheels, 5, 6, 7, 8...
Wheel speed detector, 12, 13...changeover switch, 1
4... Knob, 23, 24, 25, 26... Wheel cylinder, S1, S2, S3, S4... Detection signal, 11... Control unit.

Claims (1)

[Scope of utility model registration request] A wheel speed detector installed to detect the wheel speeds of the front and rear wheels of the vehicle, and a brake fluid pressure that regulates the brake fluid pressure on the wheel cylinder side that applies braking force to each of the front and rear wheels. An anti-skipping control means detects the locking tendency of the wheels based on the detection signal of the wheel speed detector and outputs a pressure regulation signal to avoid locking to the brake fluid pressure adjusting means of each wheel that has a locking tendency. In the four-wheel anti-skid brake system, the wheel speed detector that detects the wheel speed of the front wheel among the wheel speed detectors is capable of blocking the output of the detection signal. A four-wheel anti-skid brake system connected to the control means via a changeover switch, the control means stopping output to the brake fluid pressure adjustment means on the front wheel side in response to interruption of the detection signal. .