Combined bearing and variable speed viscous coupling

摘要

A combined variable speed viscous coupling and bearing includes a rolling element bearing that supports a driven member for relative rotation on a powered member. A viscous grease interposed and sealed with respect to the rolling elements of the bearing acts as a variable speed drive, frictionally retarding the rolling of the rolling elements when the powered member turns below a certain critical speed, thus causing the driven member to turn with the powered member in a one-to-one relationship. Above the predetermined critical speed, the rolling elements roll sufficiently through the viscous material to allow the powered member to overrun the driven member. In a preferred embodiment, the invention is disclosed as a variable speed drive for the cooling fan of a vehicle alternator.