Patent ID: 7073648

Claim:
A power transmission mechanism comprising: a drive shaft rotatably supported by housings, at least one end portion of the drive shaft projecting from the corresponding housing; and a driven member mounted on the projecting one end portion of the drive shaft by means of a one-way clutch interposed therebetween; the one-way clutch comprising: a swinging clutch portion of keyhole-section shape, including a cylindrical portion extending axially of the drive shaft and a projecting portion extending from the cylindrical portion; a clutch portion housing groove formed in the drive shaft, for housing the cylindrical portion, holding the swinging clutch portion swingably about the cylindrical portion; a collar rotatably fitted onto the drive shaft and having a slit formed such that a distal end portion of the projecting portion can project therefrom and retract thereinto; at least one engaging groove formed in an inner peripheral surface of the driven member for engagement with the distal end portion of the projecting portion; and a sealing member interposed between the housing and the collar for preventing the collar from rotating along with rotation of the drive shaft, wherein, when the swinging clutch portion is raised by the collar rotating more slowly than the drive shaft rotates, the distal end portion of the projecting portion projects from a periphery of the slit, thereby engaging the engaging groove, and when the swinging clutch portion is laid down, the distal end portion of the projecting portion retracts into the slit, thereby disengaging from the engaging groove.