Valve structure having fluid pressure actuated sealing members

Claim 1

A ball valve structure comprising a Valve body having a chamber therein and upstream and downstream flow passages in communication with the valve chamber, a valve ball mounted within the valve chamber and forming a body cavity between the valve ball and valve body, means to rotate the valve ball between open and closed positions to control the flow of fluid through said passages, an annular sealing member on opposed sides of the valve ball providing upstream and downstream sealing members, said sealing members mounted for limited longitudinal movement relative to the valve ball to provide a varying sealing pressure against the valve ball, a separate pilot valve for each sealing member mounted on an exterior surface of the valve body, each pilot valve including a body having a central cylindrical bore and three ports communicating with the bore and spaced along the valve body to provide end and intermediate ports, a cylindrical landed shuttle member slidable back and forth within the central bore between positions in which the end ports are in communication with the intermediate port, a first fluid conduit located internally of the bodies between the body cavity and one end port, a second fluid conduit located internally of the bodies between the associated sealing member and the intermediate port and a third fluid conduit located internally of the bodies between the associated flow passage and the other end port, said shuttle member having means responsive to the reaching of a body fluid pressure higher than the fluid pressure in the associated flow line moving to a position in which the first fluid conduit is in communication with the second fluid conduit thereby to urge the associated sealing member into tight engagement with the valve ball and upon the reaching of a fluid pressure in the associated flow line higher than the fluid pressure in the valve body moving to a position in which the third fluid conduit is in communication with the second fluid conduit to urge the associated sealing member toward the valve ball.