Patent ID: 8715123

Claim:
A pulley device comprising: a pulley member having an outer periphery around which a belt is wound; a shaft disposed on an inner peripheral side of the pulley member coaxially with the pulley member; and a rotation urging mechanism disposed between the pulley member and the shaft, wherein the rotation urging mechanism includes: an outer raceway surface provided on an inner peripheral side of the pulley member; an inner raceway surface disposed on an outer peripheral side of the shaft on a radially inner side of the outer raceway surface; and a ball disposed rollably between the outer raceway surface and the inner raceway surface, wherein one of the outer and inner raceway surfaces is formed about a second axis which is inclined with respect to an axis of rotation of the pulley member, and the other raceway surface is formed about a third axis which is inclined with respect to the second axis and is disposed so as to cross the one raceway surface, wherein the ball is disposed at a portion of intersection between the outer and inner raceway surfaces, and wherein the second axis is inclined with respect to the first axis such that, as the ball moves in an axial direction of the axis of rotation of the pulley member, the ball is clamped by the inner raceway surface and the outer raceway surface such that a relative rotation between the outer raceway surface and the inner raceway surface is restricted such that the shaft and the pulley member rotate integrally.