| 摘要 |
PROBLEM TO BE SOLVED: To provide an electric power steering device that can prevent adhesion of abrasion powder generated by friction between a belt and a driven pulley to a ball screw part of a rack shaft.SOLUTION: A transmission mechanism 20 is formed by screwing a ball nut 38 to a ball screw part 39 of a rack shaft 12 through a plurality of balls 40. The ball nut 38 is supported rotatably through a driven pulley 36 by a bearing 34 supported on a first housing 29. To an outer periphery of the ball nut 38 is fitted the driven pulley 36 to be integrally rotatable, and the driven pulley 36 is fixed by a ball screw fastening screw 44 which is screwed to an inner peripheral face of an end part, at a side not supported in a cantilever shape, of the driven pulley 36. The ball-screw fastening screw 44 is formed of a cylindrical lock screw extending longer in a shaft direction than the driven pulley 36, and comprises a flange part 47 protruding in a radial direction on an outer periphery of one end part thereof, whose outer peripheral surface that does not overlap with the driven pulley 36 is applied with grease. |
