Patent ID: 7195110

Claim:
A one-way clutch unit comprising: a rotating shaft; a first one-way clutch comprising: a first outer ring having in an inner periphery thereof an engagement surface and a raceway surface which are adjacent to each other; a first inner ring contacting the rotating shaft and having in an outer periphery thereof an engagement surface and a raceway surface which are adjacent to each other; first engagement members disposed between the engagement surface of the first outer ring and the engagement surface of the first inner ring; and first balls disposed between the raceway surface of the first outer ring and the raceway surface of the first inner ring; and a second one-way clutch comprising: a second outer ring having in an inner periphery thereof an engagement surface and a raceway surface which are adjacent to each other; a second inner ring having in an outer periphery thereof an engagement surface and a raceway surface which are adjacent to each other; second engagement members disposed between the engagement surface of the second outer ring and the engagement surface of the second inner ring; and second balls disposed between the raceway surface of the second outer ring and the raceway surface of the second inner ring; wherein an annular recess is provided in an inner periphery of the first inner ring of the first one-way clutch.