Electric Power Steering

Abstract

Construction of an electric power-steering apparatus is achieved that, by stably suppressing backlash of an output shaft 6a of an electric motor 5 over a long period of time, is able to stably reduce vibration and strange noise that occurs during operation. The front end section of the output shaft 6a and the base end section of a worm 7 are connected such that torque can be transmitted and such that relative displacement in the axial direction is possible An elastic member 31 having an elastic force in a direction that separates the output shaft 6a and worm 7 is provided in the connecting section between the output shaft 6a and the worm 7. Due to the elastic force of the elastic member 31, together with the tandem arrangement contact angles, the preload is applied to a pair of ball bearings 14a, 14b that support the output shaft 6a with respect to the motor case 13 such that the output shaft 6a can rotate freely.

Description

technical field [0001] The present invention relates to an electric power steering device for automobiles. Background technique [0002] In order to reduce the force required to operate the steering wheel when the steering angle is applied to the steering wheels of the car (except for special vehicles such as forklifts, usually the front wheels), electric power steering devices are widely used. Use an electric motor as an auxiliary power source. Although electric power steering apparatuses of various structures are known, in any of the structures, the auxiliary power of the electric motor is applied to the steering shaft rotated by the operation of the steering wheel via the speed reducer. A worm gear reducer is generally used as the reducer. In the case of an electric power steering system using a worm gear reducer, the auxiliary power of the electric motor is freely transmitted to the steering shaft by meshing a worm screw rotationally driven by the electric motor with a...

AI Technical Summary

Problems solved by technology

In addition, when the preload of the other ball bearing is lost, abnormal noise or vibration such as impact sound may be generated in the other ball bearing portion.

Therefore, there is a problem that only by providing an elastic member between the front end surface of the output shaft of the electric motor and the base end surface of the worm shaft, the rattling of the output shaft cannot be sufficiently prevented.

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