HIGH-PRESSURE VALVE WITH LOW-PRESSURE OPERATING DEVICE

摘要

1,213,573. Fluid-pressure servomotor systems. GENERAL GAS LIGHT CO. Feb.9, 1968 [March 3, 1967], No.6617/68. Heading G3P. [Also in Division F2] A pilot actuated valve has an inlet 12, an outlet 13 and a vent 108, a valve member 51 occupying a first position when the inlet is connected to the outlet and a second position when the inlet is disconnected from the outlet, a passage 61 interconnecting the inlet with an enclosed chamber 22 to provide constant communication therebetween, an orifice 68 in the passage to cause a pressure drop as the fluid passes therethrough, a second passage 106,104,107 interconnecting the chamber 22 with the vent 108, and an actuator 92 for selectively blocking the second passage so as to cause a pressure build up within chamber 22 to shift the valve member 51 to its first position. This shift is effected against a spring load 63 by the fluidpressure in chamber 22 acting on a diaphragm 19 to disengage the valve member from a seat 43 and close it against a seat 46 allowing fluid to flow from the inlet 12 through a passage 58 and apertures 33 in a diaphragm 21 to the outlet 13, an exhaust port (not shown) at right angles to the inlet and outlet being simultaneously isolated by the engagement of the valve member with the seat 46. The actuator 92 opens the second passage when a port 76 communicating with a diaphragm 86 is disconnected from a source S of low-pressure pilot fluid and vented to atmosphere, the valve member 51 being shifted to the right by the spring load and the fluidpressure differential on the diaphragm 21. A closed compartment may be used in place of the source S to provide an actuator responsive to changes in environmental temperature and pressure. The port 76 may also be permanently open to the atmosphere while a closed compartment on the side of the diaphragm 82 remote from the port is connected to a variable source of vacuum. The valve member 51, which may be modified by omission of the diaphragm 21 and replacement of the diaphragm 19 by a piston, may control the supply of compresed air to a cylinder.