Diaphragm piston operated valve device

Abstract

A diaphragm type valve device comprising a housing having a pair of valve chambers separated by a diaphragm piston and connected to respective fluid pressure input ports, oppositely disposed valve seats fixed in the housing in facing relation to each side of the diaphragm piston and connected to respective output ports, a pair of valve members reciprocably disposed in a central bore in the diaphragm piston and being axially biased in opposite directions by a spring compressibly installed in the central bore between the valve members, one or the other of the valve members being seatable on one or the other of the valve seats when the diaphragm piston is axially displaced by dominating pressure acting on one or the other side thereof, and stop rings concentrically fixed in the central bore adjacent the respective ends thereof for limiting axial displacement of said valve members by the spring to a spaced-apart distance somewhat greater than the fixed axial distance between the valve seats. A spring for biasing the diaphragm toward one of the valve seats, if desired, may be compressibly disposed in one of the valve chambers between the diaphragm piston and an end wall of the housing.