# US 10,502,296 B2 · Ball screw device and steering system

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- Number: US 10,502,296 B2
- Document ID: US10502296B2
- Status: Granted
- Kind: B2
- Application number: 15/607,895
- Filed: 2017-05-30
- Published: 2017-12-07
- Granted: 2019-12-10
- Earliest claimed: 2016-06-03
- Assignees: Jtekt Corporation
- Applicants: Jtekt Corporation
- Inventors: Takuya Nakayama; Toshihiro Asakura; Keisuke Ogawa
- Web page: https://patentgrep.com/patent/US10502296B2

## CPC

- F16H 25/2214: {with elements for guiding the circulating balls}
- B62D 3/08: using intermediate balls or the like
- F16H 25/2233: {with cages or means to hold the balls in position}
- B62D 3/02: mechanical
- B62D 3/04: of worm type
- B62D 3/06: with screw and nut
- F16H 25/18: for conveying or interconverting oscillating or reciprocating motions
- F16H 25/20: Screw mechanisms (with automatic reversal F16H25/12)
- F16H 25/22: with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members
- F16H 25/2204: {with balls}
- 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 cylindrical retainer configured to retain balls in a rollable manner is provided inside a ball screw nut. The retainer has retainer grooves each having a shape of an elongated hole that extends in an axial direction of a ball screw shaft so as to be inclined at a predetermined angle. A first end of the ball screw nut and a first end of the retainer, which is one of two ends of the retainer that is closer to the first end of the ball screw nut, are spaced away from each other by a distance. The terminal end of the retainer groove closest to the second end of the retainer and a ball that is closest to the second end of the ball screw nut are spaced away from each other by a distance. The distance is set equal to or larger than the distance.

## Claims

### Claim 1

A ball screw device comprising:
a ball screw shaft having a ball rolling groove disposed on an outer peripheral surface of the ball screw shaft in a helical pattern;
a ball screw nut having a ball rolling groove disposed on an inner peripheral surface of the ball screw nut in a helical pattern;
a plurality of balls provided between the ball rolling groove of the ball screw shaft and the ball rolling groove of the ball screw nut; and
a retainer arranged between the ball screw shaft and the ball screw nut, the retainer having a plurality of retainer grooves configured to retain the plurality of balls in a rollable manner, each retainer groove of the plurality of retainer grooves having (i) a straight portion extending in an axial direction of the ball screw shaft and (ii) a chamfer portion of a wall of each retainer groove in the axial direction, which intersects with the straight portion, wherein:
a distance between a first end of the ball screw nut and a first end of the retainer, which is one of two ends of the retainer that is closer to the first end of the ball screw nut, is set equal to or larger than a distance between a terminal end of the retainer groove that is closest to a second end of the retainer and a part of a last ball of the plurality of balls that is closest to a second end of the ball screw nut.

### Claim 2 (depends on 1)

The ball screw device according to claim 1, further comprising a flanged screw attached to at least one end face of the ball screw nut, the flanged screw overlapping a part of an end face of the retainer when viewed in the axial direction of the ball screw shaft.

### Claim 3 (depends on 1)

The ball screw device according to claim 1, further comprising a holding plate attached to at least one end face of the ball screw nut, the holding plate overlapping at least a part of the end face of the retainer when viewed in the axial direction of the ball screw shaft.

### Claim 4 (depends on 1)

The ball screw device according to claim 1, wherein a distance between a part closest to the first end of the ball screw nut on one of the plurality of balls that is located at a position closest to the first end of the ball screw nut and a part closest to the second end of the ball screw nut on the last one of the plurality of balls that is located at a position closest to the second end of the ball screw nut is set smaller than a distance between a first part of the retainer groove that is closest to the first end of the ball screw nut and a second part of the retainer groove that is closest to the second end of the ball screw nut.

### Claim 5 (depends on 1)

The ball screw device according to claim 1, wherein the chamfered portion is provided at a corner of the end of the retainer groove in the axial direction on an outer peripheral side of the retainer.

### Claim 6 (depends on 1)

A steering system comprising the ball screw device according to claim 1.