| 摘要 |
A skid control unit for a dual brake system having separate master cylinders serving individual wheel cylinders. The skid control unit includes a control valve and an expansion chamber device interposed in each circuit between the master cylinder and the respective wheel cylinders. The control valve is movable to a closed position to block communication between the master cylinder and the wheel cylinder in response to a predetermined signal indicative of an incipient skid condition. The expansion chamber is then permitted to increase the volume so as to relieve the wheel cylinder pressure and release the brakes. Upon reapplication, the expansion chamber is decreased in volume to increase the wheel cylinder pressure and cause brake reapplication. Subsequently, the control valve is opened to return communication between the master cylinder and the wheel cylinders. The interconnection between the expansion chamber and the control valve is such that the control valve is not reopened until a higher pressure exists in the expansion chamber than the pressure that existed at the time the control valve was closed. This permits a smoother brake reapplication and acts to assist in preventing subsequent wheel lock-up. The expansion chamber and control valve are operated, in part, by an ancillary source of fluid pressure such as the pressure of a power steering pump. A regulator maintains a pressure in the ancillary fluid that is dependent upon the pressure in the brake system. The regulator is constructed so that it is responsive to the pressure in the brake system having the higher pressure and failure of the hydraulic system of one brake circuit will not interfere with operation of the regulator. Fail safe systems are provided for bypassing the control valve and the expansion chamber of each brake circuit in the event of failure of the ancillary fluid pressure source. |
