Patent ID: 8578904

Claim:
An engine starting method comprising: a motor reverse rotation driving step of applying reverse rotation current to a motor to drivingly rotate a motor output shaft connected to the motor from an initial rotational position at which the motor begins to rotate, in a reverse rotation direction opposite in rotation to a normal rotation direction for the motor output shaft whereby by the driving in the reverse rotation direction, a second member connected to the motor output shaft is displaced relative to a first member connected to an engine output shaft, in the reverse rotation direction from a neutral position where the first member and the second member correspond to each other in the circumferential direction, to elastically deform an elastic member thereby to make the elastic member store an urging force that urges the motor output shaft in the normal rotation direction; an urged normal rotation step of stopping the electrification to the motor to release the urging force of the elastic member to make the motor output shaft rotate in the normal rotation direction so that the second member having been displaced from the neutral position relative to the first member in the reverse rotation direction returns to the neutral position; a motor normal rotation driving step of applying normal rotation current to the motor to drivingly rotate the motor output shaft in the normal rotation direction; and an engine start igniting step of igniting an engine with the engine output shaft being rotated by the rotation at the motor normal rotation driving step, wherein the driving rotation of the motor output shaft at the motor normal rotation driving step is started when the motor output shaft returns to the vicinity of the initial rotational position and has kinetic energy in the normal rotation direction.