| 摘要 |
<p>PROBLEM TO BE SOLVED: To stabilize retaining operation by means of a clutch, and to prevent deterioration in fastening force of a clutch torque caused by alternative torque at the time of opening and closing a valve. SOLUTION: A planetary gear device 3 arranged between a driving sprocket 1 and a camshaft 2 is composed of an input gear member 4 on an outer peripheral side of a small diameter part 2A of the camshaft 2, a carrier 8, planetary gears 10, 11, an output drum 5, etc. A spring clutch 14 is wound across a drum part 4C of the input gear member 4 and the output drum 5. A fastening state between the drum part 4C of the input gear member 4 and the output drum 5 is kept by the spring clutch 14. Braking force is applied to a clutch control disc 15 by means of a clutch releasing device 16, for releasing the retaining state of the spring clutch 14.</p> |
