| 摘要 |
An active suspension system for supporting a mass, such as a seat (12) on a base (16) of a vehicle, includes a hydraulic actuator (18) coupled between the seat (12) and the base (16), an pneumatic off-load device between the seat and the base (16), and a control system which actively controls the hydraulic actuator (18) and which controls the off-load member. The control system actively controls the hydraulic actuator (18) as a function of a seat position error signal. A flow control valve (70) controls the extension and retraction of the actuator (18). A proportional pressure control valve (44) is connected between a primary pressure reducing valve (42) and an inlet (72) of the flow control valve (70). During start up, the pressure control valve (44) prevents the supply of pressurized fluid to the flow control valve (70) until the flow control valve (70) is driven to its center or null position. During an electrical power failure, the solenoid operated pressure control valve (44) is spring driven to a shut off position preventing communication of pressure to the flow control valve (70).
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