Bellows sealed stem for rotary valve

Abstract

A valve body includes a chamber for the flow of fluid between an inlet and outlet thereto. A valve member, such as a ball valve member, is positioned in the chamber for rotatable movement between an open position and a closed position to open and close the chamber. A bent valve stem extends between and is connected to the valve member and a rotatable valve actuator. Rotation of the actuator moves the valve member by rotation of the valve stem between the open and closed positions. The valve stem upper end portion is displaced from the valve stem lower end portion to provide the valve stem with a bent configuration. A bellows surrounds the valve stem to provide a hermetic seal around the stem between the valve body and the actuator. The bellows has a bent configuration corresponding to the bent configuration of the valve stem. The other surface of the valve stem is positioned closely adjacent to the inner surface of the bellows to provide the bellows with support substantially along the entire length of the bellows and means are provided to minimize wear between the bellows and stem. In operation, the bellows is internally pressurized and the support provided by the valve stem prevents lateral deflection of the bellows and failure of the bellows due to distortion.