Device and method for starting engine

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.

An engine starting device comprising:

• an engine output shaft and a motor output shaft provided between an engine and a motor that are provided for driving a vehicle;
• a damper having an elastic member that absorbs variations in rotation of the engine output shaft and the motor output shaft;
• the dumber having a fist member connected to the engine output shaft and a second member connected to the motor output shaft, and the elastic member being interposed between the first member and the second member;
• a rotational position detecting section that detects the rotational position of the motor output shaft relative to the engine output shaft;
• a reverse rotation driving control mechanism that applies reverse rotation current to the motor to rotationally drive the motor output shaft from an initial rotational position at which the motor begins to rotate, in a reverse rotation direction opposite to a normal rotation direction whereby by the driving of the motor output shaft in the reverse direction, the second member is displaced in the reverse rotation direction of the motor from a neutral position at which the first member corresponds to the second member in a circumferential direction, to make the elastic member store an urging force that urges the motor output shaft in the normal rotation direction;
• an urging force releasing control mechanism that detects by the rotational position detecting section a predetermined driving rotation stopping position of the motor output shaft rotated by the reverse rotation driving control mechanism in the reverse rotation direction and that stops the application of the reverse rotation current based on a detection signal from the rotational position detecting section to release the urging force of the elastic member so that the second member displaced from the neutral position in the reverse rotation direction returns to the neutral position;
• and
• a normal rotation driving control mechanism that detects by the rotational position detecting section a predetermined driving rotation starting position of the motor output shaft rotated by the urging force of the elastic member in the normal rotation direction of the engine output shaft and that applies normal rotation current to the motor based on a detection signal from the rotational position detecting section to rotationally drive the motor output shaft in the normal rotation direction.