Patent ID: 7644722

Claim:
A hydraulically actuated valve, comprising: a housing configured and arranged to permit fluid communication between an entrance port, a control port, and a drain port; a seal member arranged inside said housing for hydraulic actuation between a valve-open position and a valve-closed position, said valve-open position permitting draining fluid flow between said entrance port and said drain port, and said valve-closed position resisting said draining fluid flow; a fluid-flow restriction valve disposed in a first fluid path along which control fluid may flow in a first direction from said control port toward said entrance port, said fluid-flow restriction valve being structured to generate a back-pressure responsive to a flow of said control fluid in said first direction, said back-pressure being effective to urge flow of actuation fluid toward said seal member; and a bleed-down port configured and arranged to permit evacuation, as bleed-down fluid, of actuation fluid confined by said seal member; and said seal member comprises an expandable diaphragm configured and arranged to be self-biased from said valve-closed position toward said valve open position.