| 摘要 |
<p>1339774 Pilot-operated relief valves SPERRY RAND CORP 10 May 1971 [20 May 1970] 13954/71 Heading G3P A pilot valve member 25 responding via 22a, 40 to the line pressure adjacent main relief valve member 19 is biased on to seat 24 by a spring 26 the setting of which is adjustable by a plunger 27 the central land 32 of which is responsive to the pressure drop across temperaturecompensated restrictor 46 when fluid flows from the main line via 29, 30, 33 to nozzle 36. Pressure downstream of restrictor 46 is controlled by a flapper 37 biased by feedback spring 26a on to the nozzle 36 and responsive to a control signal applied to coil 38. The control signal thereby determines the pressure at which the main valve member will be unseated. When the pilot valve member is unseated, fluid above piston 22 is exhausted via restrictor 43 and passage 41 so that the end lands 31, 34 of plunger 27 respond to the pressure drop across the restrictor 43 to ensure that the pilot valve closes at a lower pressure than that at which it opened.</p> |
