# US 11,441,665 B2 · Worm reducer and method for manufacturing worm reducer

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- Number: US 11,441,665 B2
- Document ID: US11441665B2
- Status: Granted
- Kind: B2
- Application number: 17/081,367
- Filed: 2020-10-27
- Published: 2021-05-06
- Granted: 2022-09-13
- Earliest claimed: 2019-11-01
- Assignees: Jtekt Corporation
- Applicants: Jtekt Corporation
- Inventors: Naofumi Kawamura; Hirofumi Ueda
- Web page: https://patentgrep.com/patent/US11441665B2

## CPC

- F16H 55/24: Special devices for taking up backlash
- B62D 5/0409: {Electric motor acting on the steering column}
- F16H 57/022: Adjustment of gear shafts or bearings (for compensating misalignment of axes of toothed gearings without orbital motion F16H1/26; for compensating misalignment of axes of planetary gears F16H1/48)
- F16H 57/023: Mounting or installation of gears or shafts in the gearboxes, e.g. methods or means for assembly
- F16H 57/12: Arrangements for adjusting or for taking-up backlash not provided for elsewhere
- F16H 2057/0213: {Support of worm gear shafts}
- F16H 2057/0222: {Lateral adjustment}
- F16H 2057/127: {using springs}
- F16H: GEARING
- B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M)

## 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.

## Claims

### Claim 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.

### Claim 2 (depends on 1)

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.

### Claim 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.