| 摘要 |
<p>A valve assembly (16) for use in a fluid system (10) includes a flow control valve (82) which controls fluid flow between a fluid inlet port (34) and a fluid supply passage (36) in response to the load requirements. A main control spool (96) is selectively movable between a neutral position and first and second actuated positions. A load sensing passage (78) communicates a load signal from an actuator (26) to the spring chamber (50) of the flow control valve (82). A drain passage (80) communicates the load sensing passage (78) with the reservoir (14) when the main control spool (96) is in the neutral position. A blocking mechanism (138) blocks the load sensing passage (78) when the main control spool (96) is in the neutral position and opens one of the inlet port (34) and the supply passage (36) to the spring chamber (50) so that the flow control spool (82) is held in an open position. Upon moving the main control spool (96) to one of its actuated positions, the drain passage is blocked from the reservoir (14) and a load pressure signal in the load sensing passage (78) moves the blocking mechanism from the blocking position to an open position and simultaneously closes the communication between the spring chamber (50) and one of the inlet port (34) and supply passage (36). This arrangement provides a system in which the actuator (26) responds more rapidly upon the main valve spool being moved to an actuated position since communication between the inlet port and supply passage is initially unrestricted. </p> |
