Patent ID: 7374013

Claim:
An electric power steering apparatus comprising: a steering assisting electric motor having an output shaft; and a speed reduction mechanism, wherein the speed reduction mechanism includes a conical first gear joined with the output shaft of the electric motor and a conical second gear to be engaged with the first gear, the first gear includes a plurality of teeth each having a tooth surface, each tooth of the first gear includes a relatively large end portion and a relatively small end portion mutually opposed in a tooth width direction, the second gear includes a plurality of teeth each having a tooth surface, each tooth of the second gear includes a relatively large end portion and a relatively small end portion mutually opposed in a tooth width direction, the mutually corresponding tooth surfaces of the first and second gears each include engaging regions to be engaged with each other, a center position in the tooth width direction of the engaging region of each tooth surface of the first gear in an unloaded state is offset by a first offset amount from a center position in the tooth width direction of the tooth surface of the first gear to the relatively small end portion of the tooth of the first gear, and a center position in the tooth width direction of the engaging region of each tooth surface of the second gear in an unloaded state is offset by a second offset amount from a center position in the tooth width direction of the tooth surface of the second gear to the relatively small end portion of the tooth of the second gear.