Electric power steering system

摘要

An electric power steering system includes a joint that connects a rotary shaft of an electric motor with a worm shaft of a speed reducer. The joint includes a first rotational element that has a boss into which a first end portion of the worm shaft is press-fitted, and a flange extending radially from the boss. The first bearing is held by a housing and supports the first end portion so that the first end portion is rotatable and movable in an axial direction. A first elastic body, which urges the worm shaft in the axial direction toward the electric motor through the first rotational element, is provided between an inner ring of the first bearing and the flange.

主权项

1. An electric power steering system comprising:
an electric motor having a rotary shaft; a speed reducer that includes a worm shaft having a first end portion and a second end portion, and a worm wheel that meshes with the worm shaft; a joint that includes a rotational element that has a boss into which the first end portion of the worm shaft is press-fitted and a flange extending radially from the boss, the joint connecting the first end portion of the worm shaft with the rotary shaft so that torque is transmittable between the first end portion of the worm shaft and the rotary shaft; a housing that houses the speed reducer; a bearing that is held by the housing and supports the first end portion of the worm shaft so that the first end portion of the worm shaft is rotatable and movable in an axial direction; an elastic body that is interposed between an inner ring of the bearing and the flange of the rotational element, and urges the worm shaft in the axial direction toward the electric motor through the rotational element; and a receiving plate that is disposed along the same axis as the flange and directly contacts the elastic body and directly contacts the flange, wherein the flange has an outer diameter that is larger than an outer diameter of the receiving plate such that the outermost surface of the flange extends a distance farther from the axis than the outermost surface of the receiving plate extends from the axis.