| 摘要 |
<p>A hydraulic servo valve arrangement of the type having a hydraulic amplifier (12) followed by a spool type servo valve second stage (18), includes a deceleration control mechanism (30). A spindle-type positioner has first and second positions which respectively permit and block flow of fluid from the first amplifier stage (12) to the first end (26) of the second stage spool (20). The hydraulic actuator urges the positioner (33) into its first position, and a spring (43) urges the positioner into a second or closed position in the event a failure mode is encountered. A solenoid valve (59) has a communicating port (58) coupled through a dropping orifice (52) to a source of fluid supply and a second port (60) coupled to drain, such that in an actuated condition, input port is at high pressure but in an unactuated condition the input port drops to low pressure. Relief channels (54) are in fluid communication with the one end of the spool member (20) and have metered orifices (51, 55) to limit the flow of hydraulic fluid when the spool transits to its null position. Relief passages (39) in communication with the positioner piston (33) have respective transit and null override orifices (39, 41) which achieve smooth movement of the positioner to push the spool member to its set position. <IMAGE></p> |
