| 摘要 |
On brake application in the event of failure of the anti-skid device of a motor vehicle hydraulic brake system, a solenoid valve 39 of a pressure-control device 9 is not energised and acts as a one-way valve opening only when master cylinder pressure exceeds a pre-set value (p sigma , Figs 3 & 4) so that the brake pressure in the rear wheel brake cylinders is reduced relative to the brake pressure in the front wheel brake cylinders in order to prevent locking of the rear wheels before locking of the front wheels of the vehicle. On brake application, when the anti-skid device is operational, the solenoid valve 39 is energised but only assumes a fully open condition when the master cylinder pressure exceeds a switching pressure (ps). The magnetic force acting on the armature of the valve is sufficient to retain the valve in its fully open position until the master cylinder pressure reduces to zero. In this manner, the switching frequency of, and thus the wear on, the pressure-control device (9) are greatly reduced. The solenoid (70) is designed, or is energized, in such a way that it is heated to a lesser extent when it is energized. With anti-skid device failure, brake fluid can return, on brake pedal release, via one-way valve 40. <IMAGE>
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