| 摘要 |
PROBLEM TO BE SOLVED: To provide a drive unit for a motor assisted bicycle, which is light in weight, and inexpensive, and can dispense with a control system with a complex form. SOLUTION: In this drive unit for a motor assisted bicycle, the torque of a motor 31 is transmitted to a driving side chain sprocket 4 by way of the crank shaft 39 of a footing pedal, an epicyclic roller reducer 40 which makes the output shaft of the motor 31 as a sun roller shaft, and a two stage gear reducer 50 for further reducing the output, and concurrently, the torque of the motor 31 at this time can be transmitted to the driving side chain sprocket 4 on condition that the aforesaid torque exceeds a definite footing torque value. |
