Patent ID: 7159690

Claim:
An electric power steering apparatus comprising a pinion provided in a shaft rotated in response to an operation of a steering member, and a rack shaft including rack teeth meshed with the pinion and movable in an axial direction, the electric power steering apparatus further comprising: an electric motor for steering assist including an output shaft; a speed reduction mechanism including a first gear connected to the output shaft in the electric motor and a second gear meshed with the first gear; and a motion conversion mechanism for converting the rotation of the second gear into an axial movement of the rack shaft, wherein the motion conversion mechanism comprises a rotating cylinder rotated in synchronization with the second gear and a screw shaft integrally provided coaxially with the rack shaft and screwed into the rotating cylinder through a rolling member, the screw shaft includes a screw groove, the first gear includes teeth, and a shape of the screw groove in the screw shaft and a shape of the teeth in the first gear are twisted in shape in a same direction relative to the respective axes when viewing the axes from similar view points, so that when the screw groove is a right-hand groove, the teeth of the first gear will be right-hand teeth, and when the screw groove is a left-hand groove, the teeth of the first gear will be left-hand teeth.