Autoclosing flow-control valve

Abstract

An autoclosing flow-control valve assembly has a housing forming an inlet chamber normally filled with a fluid under pressure, an outlet chamber, and a main valve seat between the chambers. A piston defining in the housing a control chamber carries a valve element sealingly engageable with the seat. A piston spring braced between the piston and the housing urges the piston and element into the closed position. The piston is formed with a small bleed passage extending between the control chamber and the outlet chamber. A control passage extending between the inlet chamber and the control chamber has a pilot valve that when open pressurizes the control chamber and pushes the piston and element into the open position and when closed blocks flow through the control passage. An actuating member is actuatable to open the pilot valve and an actuating spring braced between the member and the housing urges the member out of contact with the pilot valve. A bypass passage extending between the control chamber and the outlet chamber is of substantially greater flow cross section than the bleed passage. A bypass valve in the bypass passage normally blocks flow therethrough and is opened by actuation of the actuating member to permit flow through the bypass passage so that when the actuating member is actuated with the control chamber full the control chamber can be quickly drained and the valve element and piston moved by the spring into the closed position.