Pilot operated control valve having a poppet with integral pressure compensating mechanism

摘要

A pilot operated valve (110) has a main poppet (124) that selectively controls bidirectional flow of fluid between two ports (118,120) in response to pressure in a control chamber (128) on one side of the main poppet (124). The main poppet (124) has a pilot orifice (156) that is opened and closed by a pilot poppet (166). A unique mechanism (142) is provided to compensate for variation of a pressure differential on opposite sides of the pilot orifice (156). This mechanism (142) has a pair of annular end members (144,146) between which extends a spring (145) formed by a plurality of helices. Multiple passages (133,138,139,141) with check valves (134,137,140,143) extend through the main poppet to communicate the greatest pressure among the two ports (118,120) to the control chamber (128) and the lowest pressure among the two ports (118,120) to the side of the pilot orifice (156) that is opposite the control chamber (128).