| 摘要 |
The present invention concerns a vehicle anti-lock brake control system which does not require the use of an auxiliary hydraulic pump and, in the preferred embodiment, is adapted to control only the rear brakes of a four-wheel vehicle. The control system includes a normally open solenoid actuated isolation valve connected between the master cylinder and the rear wheel brakes, and a normally closed solenoid actuated dump valve connected between the rear wheel brakes and a fluid accumulator. A computer control is connected to monitor the rear wheel speed and deceleration and, during breaking of the vehicle, functions to control the application of hydraulic pressure to the rear brakes via the isolation and dump valves in order to prevent lock-up of the brakes. In the event excessive rear wheel deceleration is detected during a vehicle stop, the computer control closes the isolation valve to hold pressure to the rear brakes at a relatively constant level. If, after the isolation valve has been closed, the difference between the actual rear wheel speed and a calculated theoretical speed ramp valve exceeds a predetermined slip threshold, the dump valve is selectively opened to reduce pressure to the rear brakes and correct the wheel slip condition. The computer control is adapted to monitor several operating parameters while the system is in the anti-lock mode in order to determine whether additional pressure should be applied to the rear brakes by selectively opening the isolation valve.
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