Viscous fluid coupling having centrifugal valve means

Abstract

The viscous fluid coupling is comprised of a drive shaft having a hollow casing rotatably mounted thereon with one end of the drive shaft extending into the hollow casing. The interior of the casing is divided into a reservoir chamber and an operating chamber by means of a dividing plate secured within the housing. The rotor on the end of the shaft is rotatably mounted within the operating chamber and a thermostatically responsive valve member is rotatably mounted within the reservoir chamber for controlling the flow of fluid through a first passage extending through the divider plate. A centrifugally responsive valve member is located within the divider plate for providing additional control of the fluid through the first passage from the reservoir chamber to the operating chamber. A second passage extends through the divider plate for permitting the flow of fluid from the operating chamber to the reservoir chamber in response to a pumping action generated by relative rotation between the rotor and the casing. According to one embodiment, the centrifugally responsive valve also controls the flow of fluid through the second passage so that fluid will continue to be pumped through the second passage subsequent to the closing of the first passage by the valve. In a second embodiment, a separate flexible, resilient one-way valve is provided for controlling the flow of fluid from the operating chamber to the reservoir chamber through the second passage in response to the pumping pressure created by relative rotation between the rotor and the casing.