One-way clutch unit and one-way clutch therefor

A one-way clutch unit comprising:

• a first one-way clutch including 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 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 rolling members 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 including 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 rolling members disposed between the raceway surface of the second outer ring and the raceway surface of the second inner ring;
• wherein
• an outer diameter of a portion on a side of the raceway surface in an outer peripheral surface of the second outer ring of the second one-way clutch is smaller than an outer diameter of a portion on a side of the engagement surface in the outer peripheral surface of the second outer ring;
• wherein
• an annular recess is provided in an inner periphery of the first inner ring of the first one-way clutch;
• and wherein
• one end portion on the side of the raceway surface in the second one-way clutch is disposed in the annular recess.