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Worm speed reducer

A technology of worm reducer and worm gear, which is applied in the direction of gear transmission, belt/chain/gear, portable lifting device, etc., and can solve problems such as easy tooth noise

Inactive Publication Date: 2020-02-18
NSK LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] However, since the meshing part of the worm wheel and the worm shaft constituting the worm gear reducer has unavoidable backlash, there is a problem that tooth noise is easily generated when the rotation direction of the worm wheel changes.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

no. 1 approach

[0081] refer to Figure 1 to Figure 5 The first embodiment will be described.

[0082]

[0083] The electric power steering device is a column-assisted electric power steering device, including: a steering wheel 1, a steering shaft 2, a steering column 3, a pair of universal joints 4a, 4b, an intermediate shaft 5, a steering gear unit 6, and a pair of tie rods 7 , Electric booster 8.

[0084] The steering wheel 1 is attached to a rear end portion of a steering shaft 2 , and the steering shaft 2 is rotatably supported inside a steering column 3 . The front end portion of the steering shaft 2 is provided inside a housing 9 fixed to the front end portion of the steering column 3 , and is coupled to an output shaft 11 via a torsion bar 10 .

[0085] The output shaft 11 is rotatably supported inside the casing 9 via a pair of rolling bearings 12a, 12b. The rotation of the output shaft 11 is transmitted to the pinion shaft 13 of the steering gear unit 6 via the pair of universa...

no. 2 approach

[0110] refer to Image 6 A second embodiment will be described. The urging member 22a of this embodiment has the urging shaft part 40a and the elastic pressing part 41a. The urging shaft portion 40a has an external thread portion 44 on one side in the axial direction, and has a large-diameter shaft portion 45 having a circular cross-section on the other axial side of the external thread portion 44 . The other side in the axial direction has a small-diameter shaft portion 50 with a circular cross section. The diameter of the small-diameter shaft portion 50 is smaller than the diameter of the large-diameter shaft portion 45, and its central axis is aligned with the rotation central axis O of the biasing shaft portion 40a. 40 coaxial.

[0111] The elastic pressing portion 41a is made of an elastic material such as rubber, and is formed in a hollow cylindrical shape as a whole. Especially in this embodiment, the central axis O of the through hole 49a passing through the elasti...

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Abstract

In this worm speed reducer (16), a bias member (22) is constituted from a bias shaft part (40) and an elastic pressing part (41). The bias shaft part (40) is rotatably disposed inside a housing (9) ina state in which the rotation center axis (O40) of the bias shaft part (40) is oriented substantially parallel to the central axis of a worm wheel. The elastic pressing part (41), which is made of anelastic material, is fitted onto and fixed to a portion, in the axial direction, of the bias shaft part (40) in an eccentric manner with respect to the rotation center axis (O40) of the bias shaft part (40). By rotating the bias shaft part (40), the outer circumferential surface of the elastic pressing part (41) is pressed against the outer circumferential surface of a second bearing (20) that isfitted onto a worm shaft (17). Thus, it is possible to achieve a structure for a worm speed reducer in which backlash is reduced while preventing an increase in the size of the housing.

Description

technical field [0001] The present invention relates to a worm gear reducer assembled in an electric power steering device and the like. Background technique [0002] Power steering devices are widely used in order to reduce the force required by the driver to manipulate the steering wheel. There are two types of power steering devices: an electric power steering device using an electric motor as an auxiliary power source, and a hydraulic power steering device using hydraulic pressure as an auxiliary power source. Compared with hydraulic power steering devices, electric power steering devices are becoming mainstream due to their advantages of being smaller and lighter in size, easier to control the magnitude of auxiliary power, and less power loss from the engine. [0003] In an electric power steering device, an auxiliary power of an electric motor is supplied through a speed reducer to a rotating steering shaft based on manipulation of a steering wheel. As such a speed r...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F16H1/16B62D5/04F16H55/24H02K7/116
CPCF16H1/16F16H55/24B62D5/0409H02K7/081H02K2205/03H02K7/1166F16H57/021F16H2057/0213F16H2057/126
Inventor 藤田哲英
Owner NSK LTD