POWER STEERING APPARATUS AND BACKLASH ADJUSTMENT MECHANISM THEREFOR

摘要

A power steering apparatus includes a worm gear that transmits a rotational force of an electric motor to a steering mechanism through engagement of a worm shaft and a worm wheel and a backlash adjustment mechanism that reduces backlash between the worm shaft and the worm wheel. The backlash adjustment mechanism has a ball bearing mounted to the worm shaft, a slider movable in a movement direction substantially perpendicular to a rotation axis of the worm shaft, a first sliding surface provided on an outer circumferential side of an outer race of the ball bearing, and a second sliding surface provided on the slider and brought in sliding contact with the first sliding surface such that forward movement of the slider in the movement direction causes relative sliding of the first and second sliding surfaces to bring the worm shaft closer to the worm wheel.

主权项

1. A power steering apparatus, comprising:
a steering mechanism that has a steering shaft connected to a steering wheel and transmits a steering force of the steering wheel to steerable wheels; an electric motor that applies a rotational force as a steering assist force to the steering mechanism; a reduction gear mechanism arranged between the steering mechanism and the electric motor and including: a worm gear that has a worm shaft coupled at one end portion thereof to the electric motor and a worm wheel engaged with the worm shaft and coupled to the steering mechanism and transmits the rotational force of the electric motor to the steering mechanism; and a gear housing that has a shaft accommodation part in which the worm shaft is accommodated and a wheel accommodation part in which the worm wheel is accommodated: a ball bearing mounted to the other end portion of the worm shaft within the shaft accommodation part of the gear housing and having an inner race, an outer race and a plurality of balls to rotatably support the worm shaft; a slider movable in a movement direction substantially perpendicular to a rotation axis of the worm shaft; a first sliding surface provided on an outer circumferential side of the outer race of the ball bearing; and a second sliding surface provided on the slider in an inclined shape with respect to the movement direction of the slider and brought in sliding contact with the first sliding surface such that forward movement of the slider in the movement direction causes relative sliding of the first and second sliding surfaces to bias the worm shaft in an engagement direction that brings the rotation axis of the worm shaft closer to a rotation axis of the worm wheel.