Rotary valve

Abstract

A rotary valve has a valve body with a pair of fluid ports providing fluid exits on a face of the valve body. The fluid ports are connected to corresponding fluid channels in the valve body extending between the fluid ports and fluid inlet connections to the valve body. A fluid control plate is positioned in contact with the face of the valve body and extends across the fluid ports. The control plate has a fluid channel therein which is dimensioned to extend between the fluid ports in one position of the valve plate. The valve plate is axially mounted on an output shaft of a drive motor which is connected to the valve plate by a coupling shaft. The face of the valve body and the contacting face of the valve plates are ground precisely flat and after hard anodizing are coated with a low friction coating such as molydisulphide. The motor is arranged to urge the valve plate parallel to and against the face of the valve body by the weight of the motor and the connecting elements between the motor and the valve. The low friction coating allows a rotation of the valve plate on the valve body by the motor while providing a fluid seal therebetween to confine the fluid to the ports and channel in the valve plate. The coating exposes the ports to the channel in the valve plate in the one position of the valve plate and interrupts a fluid path between the ports and the channel in valve plate in a second position of the valve plate.