| 摘要 |
<p>694,059. Fluid-pressure servomotor-control systems. DOWTY EQUIPMENT Ltd. Dec. 10, 1951 [Dec. 19, 1950], No. 30929/50. Class 135 A hydraulic slide valve for reversibly connecting each of a pair of service conduits 10, 11 to.pressure and return conduits 7, 8 respectively, comprises a slide member 17 held on its seating face 13 by a spring-loaded thimble 15 and engageable at its ends by annular members 23, 24 and pistons 25, 26 slidable in the members 23, 24 respectively. Looseball pilot valves 47, 61 operable independently by solenoids 35, 36 control the annular members and the pistons. When both solenoids are de-energized the ball valves 47, 61 are urged on to their upper seats by pressure liquid from the conduit 7 which passes through passages 38, 43 and 57, 58 to the rear of the members 23, 24 and pistons 25, 26 whence the slide 17 is held in its neutral position, by the members 23, 24 which abut stops 31, 32 spaced apart a distance equal to the length of the slide 17. To connect, e.g. the service conduit 10 with the pressure conduit 7 and the service conduit 11 with the return conduit 8. the solenoid 35 is energized whence the ball 47 is moved to its lower seat and pressure liquid behind the member 23 and piston 25 is released to the return conduit 8 through passages 43, 19. The pressure still acting on the piston 26 moves the slide 17 to the right which in turn moves the member 23 and piston 25. To return the slide to its neutral position the solenoid 35 is de-energized, the member 23 and piston 25 again being subjected to pressure whence the pressure acting on the piston 25 balances that acting on the piston 26, the slide 17 being moved to the left by the member 23 since the member 24 is in abutment with the stop 32.</p> |
