ELECTRIC POWER APPARATUS FOR A WHEELED VEHICLE

摘要

This disclosure describes an improved electrical power apparatus (29) for assisting a rider in powering a wheeled vehicle (11) such as a bicycle (11). The apparatus (29) controllably connects a rechargeable battery (23) to a dc motor (13) engageable with a wheel (17) of the vehicle in a pedetermined fashion, such that the wheel is driven with a torque that varies with the vehicle's speed according to a predetermined non-uniform profile (Figure 5). This control advantageously can be achieved by modulating on and off a switch at a duty cycle between 0 % and 100 %, which is selected to provide a motor torque that decreases monotonically with the vehicle's speed, from a maximum value at zero speed to a predetermined intermediate value at a predetermined intermediate speed, and that remains at that predetermined intermediate value for speeds between the intermediate speed and a predetermined maximum speed. The apparatus further includes a charger (25) for charging the battery (23) using a flyback-type dc-to-dc converter (Figure 3).