| 摘要 |
PURPOSE:To make it possible to smoothly run up a steep slope with the gear ratio changed automatically in response to the torque increased by the load side by providing the 1st and 2nd external gears and a synchronous pinion shaft and by forming a reverse-preventive mechanism with a stationary internal gear sector, a free play pinion, and a cam plate. CONSTITUTION:When a power transmission device used in a toy car, etc. runs on a horizontal plane, the 2nd external gear 16 is rotated through an input pinion 19 by the rotary motion of a motor 4. The 1st and 2nd external gears 9, 16 are made synchronous in rotation under control of a synchronous pinion 23. Accordingly, a sun gear 8 and an internal gear 15 are rotated synchronous to each other, and a carrier 11 is also rotatd synchronously through a planetary gear 18, thus a wheel is rotated through an output gear 12 on the main shaft 7. When the load torque increases, then the 2nd pinion 22 goes off the 1st external gear 9, and the 1st external gear 9 makes a fixed reverse rottion, and this rotation is damped down by the action of a reverse-preventive mechanism 29 consisting of an internal gear sector 41, a free play pinion 43, a cam plate, etc. Consequently, the carrier 11 and the output gear 12 reduce their rotating speed and the driving torque increases. |
