| 摘要 |
PURPOSE:To obtain a large speed reducing ratio with a small number of gears, by providing an eccentric differential gear mechanism rotating about an eccentric shaft, a rotary lever adapted to be rotated by the rotation of an external gear, and a rotation stopping means for an internal gear. CONSTITUTION:An external gear 7 having a number of teeth slightly less than that of an internal gear 6 is relatively rotatably mounted on an eccentric shaft 4 to form an eccentric differential gear mechanism. A rotary lever 9 having an elongated hole 11 engaged with a pin 8 of the external gear 7 is rotated between two operational positions in association with the rotation of the external gear 7. A stopper lever 13 is pivotably supported at its intermediate portion between the rotary lever 9 and a case 1, so as to stop the rotation of the internal gear 6 by a reaction of the torque of the external gear 7. Accordingly, when a motor is operated, the internal gear 6 as well as the eccentric shaft 4 is hindered from rotating by the stopper lever 13. As a result, the external gear 7 is allowed to carry out hypocycloid motion in the internal gear 6 by the eccentric shaft 4 and thereby reduce the speed by the difference in number of teeth per one revolution of the eccentric shaft 4. |
