| 摘要 |
<p>An inner cylinder part (6) is provided in an inward flange (4) of a drive gear (1). A large-diameter coil spring part (22) is provided to a clutch spring (21) incorporated within the drive gear (1), a interconnecting part (23) is provided to the distal coiled end of the large-diameter coil spring part, and a small-diameter coil spring part (24) wound in a different direction relative to the winding direction of the large-diameter coil spring part (22) is provided to the small-diameter end of the interconnecting part (23). The large-diameter coil spring part (22) of the clutch spring (21) tightly binds the outside-diameter surface of the inner cylinder part (6). The small-diameter coil spring part (24) is incorporated so as to tightly bind the outside-diameter surface of a rotating shaft (41). When the drive gear (1) rotates in a direction opposite to the winding direction of the large-diameter coil spring part (22), the diameters of the large-diameter coil spring part (22) and the small-diameter coil spring part (24) are reduced, so that the rotation of the drive gear (1) is transmitted to the rotating shaft (41). The interconnecting part (23) of the clutch spring (21) has an inward spiral shape in which the winding direction is the same as the winding direction of the large-diameter coil spring part (22). When rotation torque is transmitted from the drive gear (1) to the rotating shaft (41), the interconnecting part (23) will not be loaded at high stress, and the clutch spring will be more durable. An annular cover (31) is incorporated to block off an opening at the other end of the drive gear (1), the cover (31) being connected to the drive gear (1); and the cover (31), the clutch spring (21), and the drive gear (1) being formed as a single unit to facilitate assembly.</p> |
