ELECTRIC POWER STEERING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an electric power steering device capable of eliminating a backlash by applying a proper pre-load to an engaging portion between a worm gear and a worm wheel and improving engagement strength between the worm gear and the worm wheel.SOLUTION: An electric power steering device is structured so that a pre-load direction P in which pre-load means 30 energizes a bearing 23A on the other end side is set to a radial direction passing through the central axis of the worm gear within a range of a minor angle interposed between: a direction of a radial component FL of a driving reaction which a worm gear receives from a worm wheel when the worm gear rotates in a left turn steering direction within a cross section perpendicular to an axis of the worm gear; and a direction of a radial component FR of a driving reaction which the worm gear receives from the worm wheel, when the worm gear rotates in a right turn steering direction.