Patent ID: 6349686
Filing Date: 2002-02-26
Classification: F01L

Abstract:
A hydraulically driven valve comprising:a valve body defining a first passage and a second passage; a valve member positioned in said valve body and being moveable between a first position in which said first passage is open to said second passage, and a second position in which said first passage is closed to said second passage, and said valve member including a biasing hydraulic surface and a control hydraulic surface; a biasing pressure chamber defined at least in part by said valve body and said biasing hydraulic surface; a control pressure chamber defined at least in part by said valve body and said control hydraulic surface; said biasing pressure chamber and said control pressure chamber being fluidly isolated from said first passage and said second passage; a medium pressure force on said biasing hydraulic surface; and one of a high pressure force and a low pressure force on said control hydraulic surface.