To perform assistant power control with high precision by enabling stable and precise installation of an assistant power unit and a sensing device for pedal stamping force.
In this device, one end of a hollow shaft 22 to pivot a crank shaft 6 rotatably is connected with an output sprocket 8, while the other end is connected with a motor 12 through a one-way clutch 19 and also with a crank shaft through a ratchet 23. A case of this assistant power unit 4 is configured with an inner case and outer case perpendicularly intersecting the crank shaft in which a transmission system from the motor is accommodated and a cylindrical projection 25 which is concentrical with the crank shaft and hollow shaft and pivots the hollow shaft, and the projection is inserted into a hanger pipe 38 of a frame and the side faces of the inner case and outer case are abutted to the end face of the hanger pipe, and any part of the case is coupled with the frame, and thereby the assistant power device 4 is fixed to the frame.
NISHIMURA RITSUO
SHIMADA NOBUAKI
FURUKAWA TOSHIHARU
SATO SUSUMU
