US 12,168,496 B2
Power assist device for bicycles, and bicycle
Kenji Tsukamoto, Saitama (JP)
Assigned to HONDA MOTOR CO., LTD., Tokyo (JP)
Appl. No. 17/610,517
Filed by HONDA MOTOR CO., LTD., Tokyo (JP)
PCT Filed Jun. 10, 2020, PCT No. PCT/JP2020/022838
§ 371(c)(1), (2) Date Nov. 11, 2021,
PCT Pub. No. WO2020/250926, PCT Pub. Date Dec. 17, 2020.
Claims priority of application No. 2019-109732 (JP), filed on Jun. 12, 2019.
Prior Publication US 2022/0212751 A1, Jul. 7, 2022
Int. Cl. B62M 6/50 (2010.01); B62M 6/55 (2010.01)
CPC B62M 6/50 (2013.01) [B62M 6/55 (2013.01)] 12 Claims
OG exemplary drawing
 
1. An electric power-assist device for bicycles, the device comprising: a crankshaft configured to be driven by a force transmitted from a crankarm on each side, the crankarm having a pedal; an electric motor connected to the crankshaft or the crankarm of a bicycle in a torque transmitting relationship; a battery which is provided in the bicycle and serves as a power source for the electric motor; a housing which can be attached to a frame structure of the bicycle, wherein the electric motor is provided in the housing; a rotating member rotatably supported by the housing, rotationally driven by the electric motor, and connected to the crankshaft or the crankarm of the bicycle in a torque transmitting relationship; and a control unit for controlling operation of the electric motor,
wherein the electric power assist device further comprises:
a dynamic brake circuit connected to the electric motor;
a rotational angle sensor configured to detect a crank rotational angle of the crankshaft; and
a current sensor configured to detect a value of motor current supplied to the electric motor,
wherein the control unit comprises:
a dynamic brake controller configured to stop supply of current from the battery to the electric motor and bring the dynamic brake circuit to an ON state when the crank rotational angle is within one or more predetermined crank rotational angle ranges;
a pedaling force estimator configured to estimate a pedaling force put on each pedal of the bicycle based on a value of reverse current caused by a counter electromotive force and detected by the current sensor when the dynamic brake circuit is in the ON state; and
a motor drive controller configured to control the electric motor based on the pedaling force estimated by the pedaling force estimator.