Bidirectional pressure-assisted valve seal

Claim 1

A valve structure, comprising a valve body having a central bore therethrough; a valve closure member mounted in said bore and movable between an open and closed position about an axis substantially transverse to said bore, and having a peripheral sealing surface; said valve body including an annular recess circumscribing said bore and disposed in radial alignment with said sealing surface when said closure member is closed and having a first sidewall and a second sidewall, said first sidewall including a converging tapered surface; a seal member including a peripheral portion in sealing engagement with said valve body, an inner annular sealing portion disposed to engage said sealing surface of said closure member when closed, and an intermediate flexible portion joining said peripheral portion and said inner sealing portion, the junction of said flexible portion and said inner sealing portion defining a channel having first and second side walls; resilient annular means disposed against said walls of said channel and between said annular sealing portion of said seal member and said converging surface of said first body recess sidewall for sliding on said converging surface to provide a moveable fulcrum about which said flexible portion bends for limiting movement of said sealing portion toward said first body recess sidewall and for deflecting and urging said sealing portion radially inward; and second fulcrum means on said second body recess sidewall; said annular sealing portion and said intermediate flexible portion of said seal member being substantially completely exposed to fluid pressure acting from either direction in said bore; whereby by coaction of one of said fulcrum means and said fluid pressure, sealing engagement between said seal member and said peripheral sealing surface of said closure member is improved when said fluid pressure acts on said seal member from either direction and said closure member is in a closed position.