Patent ID: 6971801
Filing Date: 2005-12-06
Classification: F16C

Abstract:
1. A bearing unit comprising: a housing; a shaft passing through said housing and rotatably supported on said housing, said shaft defining an axial direction thereof; and a pair of rolling bearings disposed between said housing and said shaft and fitted to two positions on said shaft, which are spaced apart from each other in the axial direction, at least one of said rolling bearings having an inner ring press-fitted to said shaft, said inner ring defining an intermediate portion in the axial direction at least partially including an inner raceway surface, wherein a reduced diameter part having an outer diameter smaller than the inner diameter of said inner ring and a predetermined width in the axial direction is formed on said shaft at a position corresponding to said intermediate portion of said inner ring so that inner circumferential surfaces located at both ends of said inner ring in the axial direction are interference fitted to said shaft and the inner circumferential surface at said intermediate portion thereof is clearance fitted to said shaft, wherein the predetermined width of the reduced diameter part is longer than an entire width of the raceway surface of one of the inner rings. wherein each of said pair of rolling bearings is a ball bearing including a plurality of balls and an outer ring, and further wherein a center position of said reduced diameter part of said shaft in the axial direction is substantially set at an intersection position of said inner raceway surface with a contact angle line connecting points that said ball contacts with said inner and outer rings.