Patent ID: 6029691
Filing Date: 2000-02-29
Classification: F16K,Y10T

Abstract:
An in-line control valve, comprising:a housing having an inlet port, an outlet port downstream of the inlet port, and a valve seat between said two ports;a valve assembly within said housing, said valve assembly including a valve member movable towards and away from said valve seat and having an upstream face facing said valve seat and a downstream face facing the outlet port;a valve stem fixed to the valve member and extending downstream thereof;a piston head carried by the valve stem at the downstream end thereof and having a downstream face defining a first control chamber with a first surface of the housing;a cylindrical skirt fixed to and extending downstream of the valve member and enclosing said valve stem but terminating short of said piston head to define a second control chamber with the valve member, the valve stem and a second surface of said housing;a fluid flow passageway defined by said housing to permit fluid flow therethrough in the open condition of the valve member;a pressure-control passageway defined by said valve stem establishing communication between said first and second control chambers such that the fluid pressure in said first chamber acts on the downstream face of the piston head tending to move it and the valve member towards said valve seat, and such that the fluid pressure in said second chamber acts on the downstream face of the valve member and tends to move it and the valve member also towards said valve seat, the upstream face of the piston head and a third surface of the housing defining, a third control chamber such that the fluid pressure therein acts on the upstream face of the piston head tending to move it and the valve member towards the open position of the valve member away from said valve seat; anda control port connected to a source of fluid pressure and communicating with said third control chamber for applying fluid therein to move the valve member towards its open position away from said valve seat.