BEARING ASSEMBLY FOR A POWER STEERING MECHANISM

• US 20120024618A1
• Filed: 01/22/2010
• Published: 02/02/2012
• Est. Priority Date: 01/23/2009
• Status: Active Grant

• Current Assignee: ABet SKF
• Original Assignee: ABet SKF
• Inventors: Houdayer, Christophe, Charpentier, Jacques, Bussit, Sylvain, Arnault, Benoit, Liverato, Yves, Girardin, Carole
• Granted Patent: US 8,851,227 B2
• Time in Patent Office: Days
• US Class Current: 180/447
• CPC Class Codes: B62D 5/0448 Ball nuts
• CPC Class Codes: F16C 19/06 with a single row or balls
• CPC Class Codes: F16C 19/522 related to load on the bearing, e.g. bearings with load sensors or means to protect the bearing against overload
• CPC Class Codes: F16C 2326/24 Steering systems, e.g. steering rods or columns
• CPC Class Codes: F16C 25/083 with resilient means acting axially on a race ring to preload the bearing
• CPC Class Codes: F16H 25/24 Elements essential to such mechanisms, e.g. screws, nuts F16H25/22 takes precedence

Abstract

A bearing assembly is for a mechanism including a housing and a rotatable shaft disposed within the housing. The bearing assembly includes a sleeve disposable within the housing and having an inner circumferential surface defining a bore and a radial surface extending radially inwardly from the inner surface. A bearing is disposed within the bore and includes inner and outer races and rolling elements disposed between the races, the inner race being coupleable with the shaft such that the shaft and the inner race rotate as a single unit. Further, a biasing member biases the outer race generally against the sleeve radial surface or a housing radial surface to prevent axial displacement of the outer race during shaft rotation. Preferably, a retainer couples the biasing member with the outer race to retain the bearing and the biasing member within the bore when the assembly is separate from the housing.

Claims

1. A bearing assembly for a mechanism including a housing and a rotatable shaft disposed within the housing, the bearing assembly comprising:

a sleeve disposable within the housing and having an inner circumferential surface defining a bore and a radial surface extending radially inwardly with respect to the inner surface;

a bearing disposed within the sleeve bore and including inner and outer races and a plurality of rolling elements disposed between the inner and outer races, the inner race being coupleable with the shaft such that the shaft and the inner race rotate as a single unit; and

a biasing member configured to bias the bearing outer race generally against one of the sleeve radial surface and a radial surface of the housing so as to substantially prevent axial displacement of the bearing outer race during rotation of the shaft.

2. The bearing assembly as recited in claim 1 wherein:

the outer race has an outer circumferential surface sized to engage with the sleeve inner circumferential surface so as to form one of a clearance fit and a transition fit; and

the sleeve has an outer circumferential surface sized to engage with an inner circumferential surface of the housing so as to form an interference fit.

3. The bearing assembly as recited in claim 1 wherein the biasing member is one of a spring washer and an elastomeric member.

4. The bearing assembly as recited in claim 3 wherein the spring washer is one of a spherical washer, a Belleville washer, and a wave spring washer.

5. The bearing assembly as recited in claim 1 wherein the biasing member includes a generally annular body having inner and outer radial ends and a central portion extending axially with respect to the ends, the central portion being disposable against the bearing outer race and deflectable relative to the radial ends so as to exert a force on the outer race.

6. The bearing assembly as recited in claim 1 further comprising a retainer configured to couple the biasing member with the outer race such that the bearing and the biasing member are retained within the sleeve bore when the bearing assembly is separate from the housing.

7. The bearing assembly as recited in claim 6 wherein the retainer includes a generally annular body with an axial portion engaged with the sleeve and a radial portion having a first radial surface disposed against the biasing member and an opposing, second radial surface disposable against a radial surface of the housing, the biasing member being sandwiched between the retainer radial portion and the bearing outer race.

8. The bearing assembly as recited in claim 7 wherein the retainer axial portion is generally annular and has an inner circumferential surface sized to fit about the outer circumferential surface of the sleeve so as to couple the retainer with the sleeve.

9. The bearing assembly as recited in claim 7 wherein the retainer axial portion is slidably engaged with the sleeve such that the retainer is displaceable relative to the sleeve to deflect the biasing member such that the biasing member exerts a force on the bearing outer race directed at least generally toward the sleeve retainer surface.

10. The bearing assembly as recited in claim 7 wherein the sleeve has an annular groove extending generally radially inwardly from the sleeve outer surface and the retainer axial portion has an inner end connected with the radial portion and an opposing, outer end disposed within the groove so as to couple the retainer with the sleeve.

11. The bearing assembly as recited in claim 6 wherein the biasing member and the retainer are integrally formed.

12. The bearing assembly as recited in claim 1 wherein the biasing member is coupled with the sleeve and is further configured to retain the bearing within the sleeve when the bearing assembly is separate from the housing.

13. The bearing assembly as recited in claim 12 wherein the biasing member includes an elastomeric body with an axial portion engaged with the sleeve and a radial portion having a first radial surface disposed against the outer race and an opposing, second radial surface disposable against a radial surface of the housing, the body radial portion being compressible between the outer race and the housing radial surface so as to exert a force on the outer race directed generally toward the sleeve radial surface.

14. The bearing assembly as recited in claim 13 wherein the sleeve has an annular groove extending generally radially inwardly from the sleeve outer surface and the biasing member axial portion has an inner end connected with the radial portion and an opposing, outer end disposed within the groove of the sleeve so as to slidably couple the body with the sleeve.

15. The bearing assembly as recited in claim 1 further comprising a transfer member disposed between the biasing member and the outer race, the biasing member exerting force on the transfer member so as to bias the bearing outer race against the sleeve radial surface.

16. The bearing assembly as recited in claim 1 wherein the biasing member includes an elastomeric body disposed between the sleeve radial surface and the bearing outer race, the elastomeric body being compressed when the bearing assembly is disposed within the housing such that the biasing member exerts a force on the outer race to retain the outer race disposed against the housing radial surface.

17. A power steering assembly comprising:

a screw linearly displaceable along a central axis and having at least one end connectable with steering device for turning a wheel;

a drive nut disposed about a section of the screw, rotatable about the central axis, and threadably engaged with the screw such that rotation of the nut displaces the screw along the axis;

a housing having an interior chamber; and

a bearing assembly configured to rotatably mount the drive nut within the housing chamber, the bearing assembly including;

a sleeve disposable within the housing and having an inner circumferential surface defining a bore and a radial surface extending radially inwardly with respect to the inner surface;

a bearing disposed within the sleeve bore and including inner and outer races and a plurality of rolling elements disposed between the inner and outer races, the inner race being coupled with the nut such that the nut and the inner race rotates as a single unit; and

a biasing member configured to bias the bearing outer race generally against one of the sleeve radial surface and a radial surface of the housing so as to substantially prevent axial displacement of the bearing outer race during rotation of the nut.

18. The bearing assembly as recited in claim 17 wherein:

the outer race has an outer circumferential surface sized to engage with the sleeve inner circumferential surface so as to form one of a clearance fit and a transition fit between the outer race and the sleeve; and

the sleeve has an outer circumferential surface sized to engage with an inner circumferential surface of the housing so as to form an interference fit between the sleeve and the housing.

19. The bearing assembly as recited in claim 17 further comprising a retainer configured to couple the biasing member with the outer race such that bearing and the biasing member are retained within the sleeve bore when the bearing assembly is separate from the housing.