Worm reducer and method for manufacturing worm reducer

Patent metadata

Field	Value
Publication number	US-11441665-B2
Application number	US-202017081367-A
Country	US
Kind code	B2
Filing date	Oct 27, 2020
Priority date	Nov 1, 2019
Publication date	Sep 13, 2022
Grant date	Sep 13, 2022

Abstract

A worm reducer includes a worm shaft; a worm wheel; a housing that houses the worm shaft and the worm wheel; a bearing that holds the worm shaft inside the housing; a coil spring that contacts an outer peripheral surface of the bearing and applies an urging force toward the worm wheel; and a preload member that is screwed into and fixed to the housing and pressurizes the coil spring. A winding direction of the coil spring is different from a winding direction of a thread of the preload member, and contact resistance between the coil spring and the preload member is greater than contact resistance between the coil spring and the bearing.

First claim

What is claimed is:

1. A worm reducer comprising:
a worm shaft;
a worm wheel;
a housing that houses the worm shaft and the worm wheel;
a bearing that holds the worm shaft inside the housing;
a coil spring that contacts an outer peripheral surface of the bearing and applies an urging force toward the worm wheel; and
a preload member that is screwed into and fixed to the housing and pressurizes the coil spring,
wherein a winding direction of the coil spring is different from a winding direction of a thread of the preload member, and contact resistance between the coil spring and the preload member is greater than contact resistance between the coil spring and the bearing, and
a position of a first distal end portion of a wire rod forming the coil spring is disposed within a predetermined circumferential range around a winding axis of the coil spring, so that the first distal end portion is located on a side of the bearing.

2. The worm reducer according to claim 1 , wherein the preload member has a surface that contacts the coil spring, and the surface is a flat surface perpendicular to a winding axis of the coil spring or a surface of revolution with the winding axis serving as an axis of the revolution.

3. A method for manufacturing a worm reducer including a worm shaft, a worm wheel, a housing that houses the worm shaft and the worm wheel, a bearing that holds the worm shaft inside the housing, a coil spring that contacts an outer peripheral surface of the bearing and applies an urging force toward the worm wheel, and a preload member that is screwed into and fixed to the housing and pressurizes the coil spring, the method comprising:
disposing the coil spring such that one end of the coil spring in a winding axis direction contacts the bearing; and
screwing the preload member into the housing,
wherein a winding direction of the coil spring is different from a winding direction of a thread of the preload member, and contact resistance between the coil spring and the preload member is greater than contact resistance between the coil spring and the bearing,
wherein in an initial stage in which the preload member is screwed into the housing, the coil spring is rotated together with the preload member, and
wherein in a final stage in which the preload member is screwed into the housing, a position of a first distal end portion of a wire rod forming the coil spring is disposed within a predetermined circumferential range around a winding axis of the coil spring, so that the first distal end portion is located on a side of the bearing, and the preload member and the coil spring slide along with each other towards the bearing, thereby the preload member is attached to the housing.

Assignees

• Jtekt Corp

Inventors

• Kawamura Naofumi
• Ueda Hirofumi

Classifications

• F16H1/16

  comprising worm and worm-wheel · CPC title

• F16H57/0006 Primary

  Vibration-damping or noise reducing means specially adapted for gearings (devices for varying tension of belts, ropes or chains with damping means F16H7/0829; toothed members with construction providing vibration damping F16H55/14; reducing vibrations or noise of the gearbox casing F16H57/028; suppression of vibrations or noise of gear selectors F16H59/0208; control of hydrostatic fluid gearing preventing or reducing vibrations or noise F16H61/4183) · CPC title

• F16H2057/02013

  Extension units for gearboxes, e.g. additional units attached to a main gear · CPC title

• F16H2057/0213

  Support of worm gear shafts · CPC title

• F16H57/12

  Arrangements for adjusting or for taking-up backlash not provided for elsewhere · CPC title