| 摘要 |
<p>The present invention concerns a vehicle skid control system for controlling the braking of at least one selected wheel of a wheeled vehicle. The vehicle includes a brake pedal operable by the vehicle operator and a master cylinder actuated by the brake pedal for supplying pressurized brake fluid to the associated wheel brakes. In accordance with the present invention, a normally open isolation valve is connected between the master cylinder and the selected wheel brakes, and a normally closed dump valve is connected between the selected wheel brakes and a fluid accumulator. A computer control module is connected to operate the isolation valve and the dump valve. In operation, when a slip condition of the controlled wheels is detected, the computer control module closes the isolation valve to hold fluid pressure to the controlled brakes at a relatively constant level. After a slip condition has been detected and the isolation valve has been closed to hold pressure, if the deceleration of the controlled wheels exceeds a predetermined amount, the computer control module will selectively open the dump valve to enable fluid to flow into the accumulator, thereby reducing the fluid pressure to the controlled wheel brakes and reducing the deceleration of the associated wheels. Also, after the isolation valve has been closed and the slip condition is corrected, the computer control module can detect when the vehicle travels from a relatively low friction surface such as wet asphalt to a relatively high friction surface such as a dry concrete. In these instances, the braked wheels of the vehicle which are not controlled by the skid control system will cause an increase in deceleration of the vehicle. Under these conditions, pressure to the controlled wheel brakes can generally be increased without causing a lock-up condition. The control module is responsive to an increase in wheel deceleration above a predetermined rate to selectively open the isolation valve after the valve has been closed to gradually increase pressure to the controlled wheel brakes.</p> |
