Patent ID: 8292053

Claim:
A one-way clutch comprising: an inner ring; an outer ring disposed coaxially with said inner ring; a plurality of engagement elements interposed between said inner and outer rings; and a cage holding said plurality of engagement elements to locate said plurality of engagement elements in a circumferential direction of said inner and outer rings; wherein, when said plurality of engagement elements contact said inner and outer rings, and are brought into biting engagement with said inner and outer rings, said inner and outer rings rotate in unison, and when said plurality of engagement elements are disposed out of biting engagement with said inner and outer rings, said inner and outer rings rotate relative to each other, wherein a contact pressure-increasing portion is formed on an outer peripheral surface of said inner ring, and said contact pressure-increasing portion serves to increase a contact pressure of an engagement element of the plurality of engagement elements relative to said inner ring at part of a region of contact between said engagement element and said inner ring, wherein the contact pressure-increasing portion comprises a groove, wherein the groove is formed on a cam surface provided on the outer peripheral surface of said inner ring such that the length of the groove, in a direction of rotation of the inner and outer rings is greater than a width of the groove in an axial direction of the inner and outer rings, wherein the groove is disposed between opposite edges of the cam surface or a portion where the engagement element is engaged on the cam surface, and wherein said contact pressure-increasing portion is defined by said groove and extends in the direction of rotation of said inner and outer rings.