Encapsulated balance shaft and method

摘要

A shaft assembly includes a shaft, a spacer and a cover. The body of the shaft includes a sealing portion, a balancing portion and a hollow portion which may collectively define a generally cylindrical space. The spacer substantially encloses the hollow portion of the body. The cover encapsulates the shaft body and the spacer to provide a substantially continuous cylindrical surface in sealing engagement with the sealing portion. The shaft assembly may be rotatably installed in an engine such that the balancing portion may be partially submerged in an oil bath in the engine and such that the substantially continuous cylindrical surface of the cover minimizes turbulence and aeration of the oil bath when the shaft assembly is rotated. The shaft may be configured for rotation in synchrony with a crankshaft. A method for encapsulating the shaft includes forming a continuous cylindrical surface in sealing engagement with the shaft body.