Engine starter with torque variator

A starter for an engine comprising:

• a motor which works to produce torque when electrically energized;
• a planetary gear train which includes a sun gear installed on an output shaft of the motor, planet gears meshing with the sun gear, an outer gear meshing with the planet gears, and a planetary carrier retaining the planet gears to be rotatable, the planetary gear train being responsive to input of the torque produced by the motor to output torque from the planetary carrier;
• a pinion gear which meshes with a ring gear of an engine and works to transmit the torque, as outputted from the planetary carrier, to the ring gear to start the engine;
• a one-way clutch which permits the outer gear to rotate in a first direction in which the sun gear rotates when the motor rotates to exert the torque on the ring gear for starting the engine and inhibits the outer gear from rotating in a second direction opposite the first direction;
• and
• a torque variator that selectively operates in one of an active and an inactive mode,
• wherein when the outer gear is permitted by the one-way clutch to rotate to cause the outer gear and the planetary carrier to rotate together, the inactive mode is entered to establish transmission of the torque from the motor to the pinion gear, and when the outer gear is inhibited by the one-way clutch from rotating, the active mode is entered to increase the torque transmitted from the motor to the pinion gear.