Fluid control valves

摘要

947,897. Fluid-pressure servomotor control systems. R. S. WILLIS. June 29, 1961 [April 10, 1961], No.23611/61. Heading G3P. [Also in Division F2] The control of fluid flow from an inlet 19, Fig. 2, to an outlet 21 is effected by a main valve 24 having an integral actuating piston 29, the regulation of fluid pressure to and from which is determined by a pair of pilot valves 101, 201, respectively. The inlet chamber 54 of the valve 101 is connected to both a pressure gauge G and the main valve inlet 19 via a passage 68 and a manually adjustable valve 71. The stem 100, 200 of each pilot valve is connected to a spring-loaded piston 109, 209, Fig. 5, respectively, and the pressure gauge pointer is coupled to a contact 401a or 401b. Upon the occurrence of an abnormal gauge pressure one pair of contacts 401 make to cause energization of a relay coil 303 so completing a circuit to an electric motor Ml which drives a pump P1 that supplies fluid to actuate the piston 109 and unseat pilot valve 101, Fig. 2, so that fluid in chamber 54 passes through a port 28a to act on the piston 29 and close the main valve 24. Closing movement of the stem 100 actuates a limit switch 502e, Fig. 5, and shuts down the motor Ml whereupon the piston 109 is spring-urged to reseat the pilot valve 101, Fig. 2. When a switch 307, Fig. 5, is manually or otherwise moved to the dotted-line position the circuit to the motor M1 is broken and that to another electric motor M2 is made, concomitantly the relay 303 is de-energized; motor M2 drives a pump P2 which translates piston 209 so unseating the pilot valve 201, Fig. 2, whereby the fluid above the main valve piston 29 is exhausted through a port 33a and the main valve 24 reopens. When the stem 200, Fig. 5, operates a limit switch 501c the circuit to motor M2 is broken and the piston 209 is spring-urged to reseat the pilot valve 201. The relay coil 303 may also be energized over a manual switch 305. The position of the main valve is indicated by a rod 80, Fig. 2, extending out of the valve casing from the piston 29. An isolating valve is associated with the gauge to enable the latter to be removed; the pilot valve assemblies may also be removed upon closure of manual valve 71. The switches 305, 307, Fig. 5, are housed in a control box which may be remotely disposed. Specification 914, 111 is referred to.