Air pilot operated directional control valve

摘要

An air pilot operated directional control valve for selectively connecting a normally open port to two selection ports, by an axial movement of a plunger with valve seats which are adapted to selectively close the axial open ends of the selection ports. The valve has diaphragms which define therebetween a control chamber in which the selection ports and the normally open port open. The plunger is continuously biased by a spring in one direction. The valve also has a pilot pressure chamber which is defined by one of the diaphragms, so that when the pilot pressure exceeds a predetermined value, the plunger moves in the axial direction against the spring to switch the connection between the normally open port and the selection ports.