ELECTRIC POWER STEERING SYSTEM

摘要

A reduction gear coupled to an electric motor includes: a first bearing that rotatably supports a first end portion of a worm shaft such that the worm shaft is allowed to oscillate in an oscillation direction about the first end portion; and a first elastic member that elastically urges a second bearing in such a direction that an axis-to-axis distance between the worm shaft and the worm wheel reduces. The first end portion and an output shaft of the electric motor are coupled by a joint. A second elastic member located between the joint and the first end portion elastically urges the worm shaft toward a second end portion and applies a preload on the first bearing. An outer ring of the first bearing is interposed in an axial direction by the third elastic member and the fourth elastic member.