One way clutch

Abstract

In a one way clutch, a sprag does not always turn around a center of curvature thereof, failing to move smoothly because the sprag contacts an outer ring and an inner ring on the surface. Accordingly, switching from idle rotation to locking of the clutch may cause hopping or the like of the sprag which will pop out of place to be broken. The present invention has an object to provide a one way clutch capable of allowing the stable motion of the sprag if the sprag should hop during pivotal movement and offering an increased freedom of design of a retainer and a ribbon spring. For achieving the object, a one way clutch comprises an annular space defined between an outer ring and an inner ring, sprags, a retainer and a spring, characterized in that the sprag comprises a cam surface contacting an inner circumferential surface of the outer ring, a cam surface contacting an outer circumferential surface of the inner ring and a protrusion opposing a wall surface of a pocket of the retainer. The latter cam surface and the protrusion are configured such as to have the respective curvature centers positioned at the same center of turning. On the other hand, the cam surface contacting the inner circumferential surface of the outer ring is configured to turn about the curvature center thereof positioned in the vicinity of the curvature center of the cam surface and protrusion.