Motor-driven assist unit

摘要

The invention provides a motor-driven assist unit capable of enhancing the cooling performance of a control board contained in the unit and also of lowering the center of gravity of the unit, and to provide a motor-driven assist unit capable of containing a control unit without enlargement of the motor-driven assist unit, and shortening the lengths of a signal line and a power supply line. A motor-driven assist unit (1) contains an electric motor (M) for generating an assist-power in response to a leg-power inputted to a crank shaft and a control board (82) or control unit (8) for controlling the electric motor (M), wherein the assist-power and the leg-power are synthesized and the resultant power is transmitted to a drive wheel. The motor-driven assist unit is characterized in that the control board (82) is located at a position offset forwardly, downwardly from the crank shaft (101) in a posture of the motor-driven assist unit (1) mounted on a body frame (2), and that at least a rotation sensor (822) for detecting the rotational speed of the crank shaft (101) is mounted on the control board (82), and the control board (82) is disposed near a rotor (111) rotated in synchronization with the crank shaft (101) in such a manner that a positional relationship between the rotation sensor (822) and the rotor (111) is kept at a predetermined relation. <IMAGE>