Patent ID: 8757311

Claim:
A motorized driving device for mounting to a frame of a bicycle, said bicycle comprising a pedal drive mechanism coupled to a chain for transferring a drive force to at least one chainwheel, said motorized driving comprising: a) a power source of rotary power, said power source further comprising: i) a battery pack; and ii) an electric motor coupled to said power transmission mechanism; said battery pack detachably fixed to said electric motor; said battery pack electrically connecting to said electric motor to provide electric power to said electric motor; and b) a power transmission mechanism for coupling between said pedal drive mechanism and said chain; said power transmission mechanism further comprising a first unidirectional power transmission module and a second unidirectional power transmission module, such that an auxiliary power transmitted by said power transmission mechanism from said power source to said chain is independent from a pedal power transmitted by said power transmission mechanism from said pedal drive mechanism to said chain; wherein said first unidirectional power transmission module further comprising an active flange for coupling to said pedal drive mechanism, and said second unidirectional power transmission module further comprises a passive flange coupled to said power source; said active flange providing said pedal power from said pedal drive mechanism to said chain; said passive flange providing said auxiliary power from said power source to said chain; said first unidirectional power transmission module further comprising: i) a plurality of pawl bases fixed on said passive flange; ii) a plurality of pawls each disposed in one of said plurality of pawl bases; and iii) a first ratchet mounted on an inner circumference of a primary gear; said first ratchet further comprising a plurality of first saw teeth formed on an inner circumference of said first ratchet; said plurality of first saw teeth engaging with said plurality of pawls in a way that when said primary gear rotates in a first direction with respect to said passive flange, said plurality of pawls driving said passive flange to move in said first direction; when said passive flange rotates in said first direction with respect to said primary gear, said primary gear not driven by said passive flange.