| 摘要 |
PROBLEM TO BE SOLVED: To install an auxiliary power unit to a general bicycle without necessity to modify the vehicle body by constructing the auxiliary power unit to transmit auxiliary power to crank shaft from torque accumulation means using constant force spring. SOLUTION: A bicycle 1 is a general bicycle that is commercially available and used all-purposely. The bicycle 1 is disposed with an auxiliary power unit 2 that is equipped with a torque accumulation means which employs a constant force spring and is tied to the lower end portion of a bottom pipe 4 and bracket lug 3. A sprocket 19 is mounted to a driving shaft 18 of the auxiliary power unit 2 by means of one-way clutch, a sprocket 20 is fixed to a crank shaft on a left crank 14L side, and a stepped belt 21 is suspended. By operating an auxiliary power switching means, the driving shaft 18 becomes rotatable counterclockwise by accumulated torque. The accumulated torque is transmitted to the sprocket 20 via the sprocket 19 and steeped belt 21, and the crank shaft is rotated and driven to assist running forward of the bicycle 1.
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