Fluid operated gate valve for use with vacuum equipment

Abstract

A gate valve for use with vacuum equipment is provided in which a gate assembly is opened and closed by a fluid operated device, such as a pneumatic cylinder. The gate assembly is enclosed in a valve housing. The valve housing has aligned openings therein, and the gate assembly is moved reciprocally between the walls and parallel to the planes of the aligned openings therein, to an open position and to a closed position with respect to the openings. The gate assembly comprises two gates which are intercoupled by a bellows, the bellows defining a hermetically sealed pressure vessel with the gates. The gate assembly is coupled to a piston in the pneumatic cylinder by a piston rod. The gate assembly is moved to its closed position when pressurized fluid is introduced to one end of the pneumatic cylinder; and the gate assembly is moved to its open position when pressurized fluid is introduced to the other end of the cylinder. When the gate assembly is moved to its closed position, a valve opens within the pneumatic cylinder, and pressurized fluid from the pneumatic cylinder is caused to enter the pressure vessel between the gates. This pressurized fluid forces the gates against seats mounted on the valve housing around the respective openings therein. Metal seals are provided for the gates, in the form of layers of relatively soft metal around the gates. The valve housing itself may be evacuated to reduce pressure differential across the gate-seat junctions and minimize molecular leakage. Relief grooves are provided adjacent the edges of the gates so that the outer perimeters of the gates are relieved to be deflected when the gates are closed so as to provide a resilient stress on the gate seals. This resilient stress serves to maintain the gates in a sealed condition even in the presence of temperature changes and resulting thermal expansion and contraction.

Dependencies are inferred from the claim text.