GB2432649A

GB2432649A - A steering wheel arrangement with an integrally formed ball bearing race

Info

Publication number: GB2432649A
Application number: GB0523835A
Authority: GB
Inventors: Laurent Groleau; Romain Chebret; Etienne Chapelain
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 2005-11-23
Filing date: 2005-11-23
Publication date: 2007-05-30
Also published as: GB0523835D0; EP1951563A4; WO2007061355A1; EP1951563A1

Abstract

A steering wheel arrangement comprising: a fixed element; a first rotatable element which is mounted on the fixed element for rotation relative thereto by means of a first ring bearing; and a second rotatable element which is mounted on the fixed element for rotation relative thereto by means of a second ring bearing, wherein the first and second rotatable elements engage one another so that rotation of the first rotatable element causes rotation of the second rotatable element, wherein the first and second ring bearings each comprise respective inner and outer races and a plurality of ball bearings that are retained between the races, and either at least one of the races is formed integrally and directly on a surface of an element, or one of the races is not a ring shaped element with a groove or cut-away portion. Various embodiments show some or all of the races formed on an element. The arrangement support a non-rotating hub driven by a ring gear and pinion.

Description

A STEERING WHEEL ARRANGEMENT

Description of Invention

THIS INVENTION relates to a steering wheel arrangement, and in particular concerns a steering wheel arrangement in which the steering wheel has a central, non-rotating hub, around which an outer peripheral part of the steering wheel may be rotated.

It has been previously proposed to provide a steering wheel unit for use in a motor vehicle. The steering wheel is mounted to rotate relative to a fixed housing, and the axis upon which the steering wheel rotates is offset from the axis of the steering column. The steering column carries a pinion gear, and the steering wheel carries a ring gear which meshes with part of the pinion gear. As the steering wheel rotates, so the steering wheel column is rotated through the interaction between the ring gear and the pinion gear.

In one embodiment of a steering wheel of this type, it is possible to mount a central air-bag unit, with the air-bag unit remaining stationary while the steering wheel rotates. This sort of arrangement enables a specially-shaped air-bag to be utilised and also facilitates the mounting of control buttons or the like on the upper surface of the air-bag unit.

A typical steering wheel arrangement incorporates a large number of parts, and there may be some cumulative tolerances when many parts are put together. This can particularly be the case in the above-mentioned type steering wheel arrangement because there may be some "play" between the pinion on the steering column and the ring gear provided on the steering wheel. This gives the steering wheel an undesirable "feel" when the motor vehicle is being driven.

The present invention seeks to provide an improved steering wheel arrangement.

Accordingly, one aspect of the present invention provides a steering wheel arrangement comprising: a fixed element; a first rotatable element which is mounted on the fixed element for rotation relative thereto by means of a first ring bearing; and a second rotatable element which is mounted on the fixed element for rotation relative thereto by means of a second ring bearing, wherein the first and second rotatable elements engage one another so that rotation of the first rotatable element causes rotation of the second rotatable element, wherein the first and second ring bearings each comprise respective inner and outer races and a plurality of ball bearings that are retained between the races, and at least one of the races is formed directly on a surface of the first or second rotatable element or the fixed element.

Advantageously, the inner race of the first ring bearing is formed on an outer surface of the fixed element.

Preferably, the outer race of the first ring bearing is formed on an inner surface of the first rotatable element.

Conveniently, the outer race of the second ring bearing is formed on an inner surface of an aperture formed through the fixed element.

Advantageously, the inner race of the second ring bearing is formed on an outer surface of the second rotatable element.

Preferably, the inner or outer race comprises a groove formed in a substantially cylindrical surface of one of the first or second rotatable elements or the fixed element.

Conveniently, the first rotatable element is attached to an outer peripheral surface of the fixed element by the first ring bearing, and a portion of the first rotatable element comprises a toothed inner surface.

Advantageously, the second rotatable element is provided in an aperture formed through the fixed element and is attached to an inner surface of the aperture by the second ring bearing, and a portion of the second rotatable element comprises a toothed outer surface.

Preferably, the toothed inner surface of the portion of the first rotatable element engages the toothed outer surface of the portion of the second rotatable element so that rotation of the first rotatable element causes rotation of the second rotatable element.

Conveniently, the steering wheel arrangement further comprises a steering wheel attached to the first rotatable element.

Advantageously, the steering wheel arrangement further comprises a steering column attached to the second rotatable element.

Preferably, the steering wheel arrangement further comprises a hub which is attached to the fixed element and which does not rotate upon rotation of the first and second rotatable elements.

Another aspect of the present invention provides a steering wheel arrangement comprising: a fixed element; a first rotatable element which is mounted on the fixed element for rotation relative thereto by means of a first ring bearing; and a second rotatable element which is mounted on the fixed element for rotation relative thereto by means of a second ring bearing, wherein the first and second rotatable elements are at least indirectly connected to one another so that rotation of the first rotatable element causes rotation of the second rotatable element, wherein the first and second ring bearings each comprise respective inner and outer races and a plurality of ball bearings, and at least one of the races is formed without a dedicated bearing element.

A further aspect of the present invention provides a vehicle comprising a steering wheel arrangement according to the above.

In order that the present invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompany drawings, in which: Figure 1 shows a cut-away view of components of a known steering wheel arrangement; Figures 2 to 6 show cut-away views of steering wheel arrangements embodying the present invention; Figure 7a shows a known steering wheel arrangement; and Figure 7b shows a steering wheel arrangement embodying the present invention.

With regard firstly to figure 1, components of a known steering wheel assembly 1 are shown. The known steering wheel assembly 1 comprises a fixed element 2 which takes the form of a generally circular, substantially planar disc with a generally circular, off-centre aperture 3 provided therein.

Mounted on an outer peripheral surface 4 of the fixed element 2 is a first bearing element 5, which takes the form of a ring of generally rectangular cross-section but having a circumferential groove 6 running around the outer surface thereof. A plurality of first ball bearings 7 are received in the groove 6.

A second bearing element 8 is also provided, again being ring-shaped and having a generally rectangular cross-section but having a groove 9 running around the inner surface thereof. The diameter of the second bearing element 8 is slightly larger than that of the first bearing element 5, and the first ball bearings 7 are also received in the groove 9 of the second bearing element 8, so that the ball bearings 7 are sandwiched between the first and second bearing elements 5, 8. It will be understood by a skilled person that the first and second bearing elements 5, 8 and the ball bearings 7 form a first ring bearing 10, with the respective grooves 6, 9 acting as the inner and outer races of the bearing 10. The second bearing element 8 may therefore rotate freely with respect to the first bearing element 5 about the axis of the disc of the fixed element 2, with the first ball bearings 7 rotating as this occurs.

A steering-wheel element 11 is attached to the second bearing element 8. The steering-wheel element 11 forms part of a steering wheel, or is adapted to be at least indirectly connected to a steering wheel.

It will thus be appreciated that a non-rotating hub may be connected to the fixed element 2. The steering-wheel element 11 may rotate with respect to the fixed element 2 and, therefore, with respect to the non-rotating central hub.

The steering wheel element 11, which has generally circular symmetry, has a ring portion 12 which projects perpendicularly away from the plane of the fixed element 2, and an inward-facing rim portion 13 which projects inwardly from the ring portion 13 towards the central axis of the fixed element 2. The steering wheel element 11 is therefore approximately L-shaped in cross-section, with one arm of the L comprising the ring portion 12 and being attached to the second bearing element 8 and the second arm of the L projecting inwardly to form the rim portion 13. An inner surface of the rim portion 13 is provided with a toothed interior 14 to form a ring gear.

Mounted on the inner surface 15 of the aperture 3 is a second ring bearing 34.

The second ring bearing 34 comprises a third bearing element 16, which is attached to the inner surface 15 and is ring-shaped with a generally rectangular cross-section having a groove 17 running around the inner surface thereof, and a fourth bearing element 18 which has a smaller diameter than the third bearing element 16 and is again generally ring-shaped with a generally rectangular cross-section but with a groove 19 running around an outer peripheral surface thereof. Second ball bearings 20 are between the third and fourth bearing elements 16, 18 and are received in the grooves 17, 19 thereof. It will therefore be appreciated that the grooves 17, 19 form inner and outer races respectively of the second ring bearing 16, and that the outer race may rotate freely with respect to the inner race, with the second ball bearings 20 rotating as this occurs.

Connected to the fourth bearing element 18 is a steering column element 21, which forms part of a steering column or is adapted to be at least indirectly attached to a steering column. The steering column element 21 comprises a cylindrical body portion 22, with the fourth bearing element 18 being mounted on an outer surface of the cylindrical body portion 22. The cylindrical body portion 22 projects away from the plane of the fixed element 2, in the same direction as does the steering wheel element 11, and this projecting part is provided with a substantially disc-shaped pinion portion 23, which lies in a plane that is parallel to that of the fixed element 2, is rather wider than the body portion 22 and has a toothed periphery 24.

It will be understood that, because the aperture 3 in which the steering column element 21 is received is off-centre in the fixed element 2, the axis of rotation of the steering column element 21 will be offset with respect to the axis of rotation of the steering wheel element 11. The arrangement is such that the portion of the toothed periphery 24 of the pinion portion 23 which is closest to the edge of the fixed element 2 meshes with the rim gear created by the toothed inner surface 14 of the rim portion 13 of the steering wheel element 11. Thus, rotation of the steering wheel element 11 with respect to the fixed element 2 will, through the interaction of the rim gear and the pinion portion 16, cause rotation of the steering column element 21 with respect to the fixed element 2 in the same sense as the rotation of the steering wheel element 11.

It will be understood how the above-described arrangement allows an outer part of the steering wheel of a motor vehicle to be rotated, and cause corresponding rotation of the steering column, while allowing a central hub of the steering wheel to remain stationary during this rotation.

Figure 2 shows components of a first steering wheel arrangement 25 embodying the present invention. In common with the known steering wheel arrangement 1 described above, the first steering wheel arrangement 25 embodying the present invention comprises a disc-shaped fixed element 2 having an off-centre circular aperture 3 therein, and also has a steering wheel element 11 and steering column element 21 as described above.

However, with regard to the first ring bearing 10, the inner race of the first ring bearing 10 comprises a groove 26 which is formed directly on the outer surface 4 of the fixed element 2, and the outer race comprises a groove 27 which is formed directly on the inner surface of the steering wheel element 11.

The first ball bearings 7 are sandwiched directly between the fixed element 2 and the steering wheel element 11, and are received in the grooves 26, 27 formed therein. It will therefore be understood that the steering wheel element 11 may rotate freely with respect to the fixed element 2, with the first ball bearings 7 rotating as this occurs, without the need for separate inner and outer bearing elements 5, 8, as were discussed above in relation to the known steering wheel arrangement 1.

Similarly, with regard to the second ring bearing 34, the inner race comprises a groove 28 which is formed directly on the inner surface of the aperture 3, and the outer race comprises a groove 29 which is formed directly on an outer surface of the cylindrical body portion 22 of the steering column element 21 The second ball bearings 20 are sandwiched between the fixed element 2 and the steering column element 21, and received in the grooves 28, 29 formed therein. It will be appreciated that the steering column element 21 may therefore rotate freely with respect to the fixed element 2, with the second ball bearings 20 rotating as this occurs, again without the need for separate inner and outer bearing elements 16, 18.

It will be appreciated that this arrangement allows the components to rotate with respect to one another as required, but with a reduced number of parts and a simpler assembly for the steering wheel arrangement, which will decrease cost, decrease manufacturing tolerances and reduce the number of components which may develop faults. The performance of the steering wheel arrangement will also be improved in terms of friction torque, mechanical stiffness and the frequency of the mechanism.

Figure 3 shows a second steering wheel arrangement 30 embodying the present invention. The second steering wheel arrangement has the same components as the first steering wheel arrangement 25, except that the second ring bearing 34 has a separate bearing element (corresponding to the fourth bearing element 18) which is attached to the outer surface of the cylindrical body portion 22 of the steering column element 21. The outer race of the second ring bearing 16 is, however, provided (in common with the first steering wheel arrangement 25) by a groove 28 provided in the inner surface of the aperture 3.

Figure 4 shows a third steering wheel arrangement 31 embodying the present invention. The third steering wheel arrangement 31 has the same parts as the second steering wheel arrangement 30, but a separate bearing element (corresponding to the second bearing element 8) is provided, mounted on the inner surface of the steering wheel element 11, to provide the outer race of the first ring bearing 10. The inner race of the first ring bearing 10 is, however, (in common with the first steering wheel arrangement 25) provided by a groove 26 which is formed directly in the outer surface of the fixed element 2.

Figure 5 shows a fourth steering wheel arrangement embodying the present invention. The fourth steering wheel arrangement 32 is the same as the second steering wheel arrangement 30, except that a separate bearing element (corresponding to the third bearing element 16) is provided to form the outer race of the second ring bearing 16. Separate bearing elements are, therefore, provided to form both the inner and outer races of the second ring bearing 16.

Figure 6 shows a fifth steering wheel arrangement 33 embodying the present invention. The fifth steering wheel arrangement 33 has the same components as the fourth steering wheel arrangement 32, except that a separate bearing element (corresponding to the second bearing element 8) is provided, attached to the inner surface of the steering wheel element 11, to form the outer race of the first ring bearing 10.

Thus, in the fifth steering wheel arrangement 33, separate bearing elements are provided to form the inner and outer races of the second ring bearing 16, and the outer race of the first ring bearing 10. The inner race of the first ring bearing 10 is, however, provided by a groove formed directly into the outer surface of the fixed element 2.

It will be appreciated that, in all of the above-described steering wheel arrangements 25, 30, 31, 32, 33 embodying the present invention, at least one of the inner and outer races of at least one of the first and second ring bearings is formed directly into a surface of the steering wheel element 11, the steering column element 21, or the fixed element 2.

Figures 7a and 7b show the known steering wheel arrangement 1 and the first steering wheel arrangement 25 embodying the present invention, respectively, in conjunction with other elements of a steering wheel arrangement. Like reference numerals have been employed to designate like parts. It can be seen that the fixed element 2 is mounted on a support 41, and that the steering wheel element 7 is connected to a steering wheel frame 42.

It will be appreciated that, when ring bearings formed from dedicated bearing elements (as used in the known steering wheel arrangement 1) are used, it is important that the bearing elements are braced against axial movement (i.e. movement in a direction parallel with the axis around which the bearing rotates). With reference to figure 1, it can be seen that the fourth bearing element 19 is received in an annular recess 35 in the outer surface of the cylindrical body part 22 of the steering column element 21. A top edge of the fourth bearing element 14 is abutted against an end waIl 36 of the recess 35, and it will be appreciated that this abutment against the end wall 36 prevents the fourth bearing element 19 from being displaced in a direction towards the end wall 36 (upwards, in the orientation of figure 1).

When the fourth bearing element 19 is fully received in the recess 35, a disc-shaped first retaining member 37 is inserted into an annular cavity 38 which is formed into the outer surface of the cylindrical body portion 22 of the steering column element 21, so that an outer portion of the disc protrudes outwardly from the cylindrical body portion 22. The protruding part of this first retaining member 37 then abuts against the furthest end of the fourth bearing member 19 from the end thereof which abuts the end wall 36. It will be appreciated that the fourth bearing element 19 is now prevented from being displaced axially in either direction.

Referring to figure 7a, it can be seen that each of the four bearing elements 5, 8, 16, 18 is received in a respective recess and abuts an end wall thereof, with a plurality of retaining members 40 being provided to restrain the bearing elements from being displaced in the opposite direction to that in which the bearing elements abut the end walls.

It will be appreciated that this arrangement requires the preparation and assembly of a large number of components, thus increasing the overall cost and decreasing the life expectancy of the steering wheel arrangement 1. In addition, it will be seen that a large screw 39 is required to secure certain ones of the retaining members 40 to the support 41.

By contrast, with reference to figure 7b, it can be seen that, when the inner and outer races of the first and second ring bearings 10, 34 comprise grooves 26, 27, 28, 29 which are formed directly into the fixed element 2, the steering wheel element 11 and the steering column element 21, the need for the retaining members is removed. It will therefore be appreciated that the construction of the steering wheel arrangement is further simplified since these retaining members need not be included. The overall machining tolerances of the steering wheel arrangement are also improved.

In the above description, the term "steering wheel" is used to refer to a part of a steering arrangement that a user may grasp and rotate to control a vehicle.

It is to be understood that the term "steering wheel" may relate only to an outer portion of the steering arrangement, since an inner portion of the steering arrangement (from a user's point of view) will not rotate with the rotatable part of the steering arrangement.

It will also be appreciated that the steering arrangement need not comprise a complete wheel, and the term "steering wheel" relates to any steering arrangement which can be rotated, irrespective of the shape.

In this specification, the term "dedicated bearing element" means an element which is provided solely to form part of a ring bearing, and should be interpreted as generally comprising a ring-shaped element with a substantially rectangular cross-section, with a groove or other cut-away portion formed in an inner or outer surface thereof to accommodate ball bearings.

It will be understood that the present invention provides a steering wheel arrangement which has fewer moving parts than conventional steering wheel arrangements, and which will display superior characteristics in terms of friction torque, mechanical stiffness and the frequency of the steering wheel arrangement.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS

1. A steering wheel arrangement comprising: a fixed element; a first rotatable element which is mounted on the fixed element for rotation relative thereto by means of a first ring bearing; and a second rotatable element which is mounted on the fixed element for rotation relative thereto by means of a second ring bearing, wherein the first and second rotatable elements engage one another so that rotation of the first rotatable element causes rotation of the second rotatable element, wherein the first and second ring bearings each comprise respective inner and outer races and a plurality of ball bearings that are retained between the races, and at least one of the races is formed directly on a surface of the first or second rotatable element or the fixed element.

2. A steering wheel arrangement according to Claim 1, wherein the inner race of the first ring bearing is formed on an outer surface of the fixed element.

3. A steering wheel arrangement according to Claim 1 or 2, wherein the outer race of the first ring bearing is formed on an inner surface of the first

rotatable element.

4. A steering wheel arrangement according to any preceding claim, wherein the outer race of the second ring bearing is formed on an inner surface of an aperture formed through the fixed element.

5. A steering wheel arrangement according to any preceding claim, wherein the inner race of the second ring bearing is formed on an outer surface of the second rotatable element.

6. A steering wheel arrangement according to any preceding claim, wherein the inner or outer race comprises a groove formed in a substantially cylindrical surface of one of the first or second rotatable elements or the fixed element.

7. A steering wheel arrangement according to any preceding claim, wherein the first rotatable element is attached to an outer peripheral surface of the fixed element by the first ring bearing, and a portion of the first rotatable element comprises a toothed inner surface.

8. A steering wheel element according to claim 7, wherein the second rotatable element is provided in an aperture formed through the fixed element and is attached to an inner surface of the aperture by the second ring bearing, and a portion of the second rotatable element comprises a toothed outer surface.

9. A steering wheel arrangement according to claim 8, wherein the toothed inner surface of the portion of the first rotatable element engages the toothed outer surface of the portion of the second rotatable element so that rotation of the first rotatable element causes rotation of the second rotatable element.

10. A steering wheel arrangement according to any preceding claim further comprising a steering wheel attached to the first rotatable element.

11. A steering wheel arrangement according to any preceding claim further comprising a steering column attached to the second rotatable element.

12. A steering wheel arrangement according to any preceding claim further comprising a hub which is attached to the fixed element and which does not rotate upon rotation of the first and second rotatable elements.

13. A steering wheel arrangement comprising: a fixed element; a first rotatable element which is mounted on the fixed element for rotation relative thereto by means of a first ring bearing; and a second rotatable element which is mounted on the fixed element for rotation relative thereto by means of a second ring bearing, wherein the first and second rotatable elements are at least indirectly connected to one another so that rotation of the first rotatable element causes rotation of the second rotatable element, wherein the first and second ring bearings each comprise respective inner and outer races and a plurality of ball bearings, and at least one of the races is formed without a dedicated bearing element.

14. A vehicle comprising a steering wheel arrangement according to any preceding claim.

15. A steering wheel arrangement substantially as hereinbefore described, with reference to Figures 2 to 6 and 7b of the accompanying drawings.

16. Any novel feature or combination of features disclosed herein.