Patent ID: 8505675
Filing Date: 2013-08-13
Classification: B62D,F16D

Abstract:
1. A power steering apparatus comprising: a steering mechanism constructed to transmit a rotational operation of a steering wheel to steerable road wheels; an electric motor having a motor output shaft rotatably supported by a first bearing, the electric motor providing the steering mechanism with a steering force via the motor output shaft; a worm gear including a worm wheel disposed on the steering mechanism, and a worm shaft rotatably supported by a second bearing and being engageable with the worm wheel; and a joint which connects the motor output shaft with the worm shaft so as to transmit a rotational torque of the motor output shaft to the worm shaft; the joint comprising: a first boss disposed on an axial end portion of the motor output shaft which is located on a side of the worm shaft; a plurality of first projections disposed on the first boss in a circumferential direction of the first boss, the respective first projections extending in a radial direction of the first boss, a second boss disposed on an axial end portion of the worm shaft which is located on a side of the motor output shaft, in an opposed relation to the first boss in an axial direction of the motor output shaft; a plurality of second projections disposed on the second boss in a circumferential direction of the second boss and arranged between the first projections disposed adjacent to each other in the circumferential direction of the first boss, the second projections each extending in a radial direction of the second boss and transmitting a rotational torque of the electric motor transmitted through the first projections to the worm shaft; a first elastic member disposed between an axial end surface of the first boss and an opposed axial end surface of the second boss which is opposed to the axial end surface of the first boss, the first elastic member being made of a metal material and formed to be elastically deformable in the axial direction the motor output shaft, and a second elastic member disposed between the axial end surface of the first boss and the opposed axial end surface of the second boss, the second elastic member being made of at least one of a resin material and a rubber material, the second elastic member cooperating with the first elastic member to generate an elastic force in such a direction as to move the worm shaft away from the motor output shaft, the second elastic member being compressively deformable so as to reduce an amount of deformation of the first elastic member when the first elastic member is compressively deformed due to a relative displacement of the motor output shaft and the worm shaft.