Gear arrangement

Abstract

A steering-wheel arrangement is disclosed which comprises a steering-wheel having a first gear element. A second gear element is provided which is mounted on a steering column. The first and second gear elements inter-engage one another and the arrangement is further provided with an anti-backlash gear which is mounted on one of the gear elements. The anti-backlash gear has teeth configures to as to align substantially with the teeth of the gear element upon which it is mounted, and the anti-backlash gear is biased relative to the gear element upon which it is mounted towards a position in which the teeth of the anti-backlash gear become displaced from the corresponding teeth of the gear element. This gear arrangement has been found to provide improved “feel” for a person driving a motor vehicle.

Description

THE PRESENT INVENTION relates to a gear arrangement. The gear arrangement of the invention may find a particular application in the context of a steering wheel, for example in a motor vehicle.

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

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 enables a specially shaped air-bag to be utilised and also facilities the mounting of control buttons or the like on the upper surface of the air-bag unit.

It has been found that with a steering wheel of this type, 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.

According to the present invention, there is provided a gear element, the gear element having a toothed portion dimensioned to engage with a co-operating gear element, the gear element having an anti-backlash gear, the anti-backlash gear having teeth corresponding to the teeth of the gear element, the anti-backlash gear being mounted to the gear element with the teeth thereof substantially in alignment with the teeth of the gear element, there being a resilient element to bias the teeth of the anti-backlash gear to a position slightly displaced from the corresponding teeth of the gear element.

Preferably, there are two anti-backlash elements, each anti-backlash element having teeth corresponding to the teeth of the gear element, the anti-backlash elements being mounted to the gear element with the teeth thereof substantially in alignment with the teeth of the gear element being biased resiliently away from each other.

According to another aspect of the present invention, there is provided a steering-wheel arrangement comprising: a steering wheel having a first gear element; and a second gear element mounted on or mountable on a steering column; the first and second gear elements inter-engaging one another; the arrangement further comprising at least one anti-backlash gear mounted on one of said gear elements, the or each anti-backlash gear having teeth configured so as to align substantially with the teeth of said gear element upon which it is mounted, the anti-backlash gear being rotatably biased, relative to the gear element upon which it is mounted, towards a position in which the teeth of the anti-backlash gear are displaced from the corresponding teeth of the gear element.

Preferably, two said anti-backlash gears are mounted on said gear element, the two anti-backlash gears being biased in opposite directions.

Advantageously, said gear element on which the or each anti-backlash gear is mounted is a ring gear.

Alternatively, said gear element on which the or each anti-backlash gear is mounted is a pinion gear.

Preferably, the pinion gear is provided with two anti-backlash gears, the anti-backlash gears each being in the form of a plate, each plate having an aperture therein, the aperture defining portions to engage spring elements, the apertures of the two anti-backlash gears being co-aligned and receiving spring elements.

Advantageously, each spring element is of substantially “C” shape, each spring element passing through part of the aperture in one plate which engages the spring element and part of the aperture in the other spring plate which accommodates the spring element.

Conveniently, part of the aperture that engages the spring element is an outwardly directed part of the aperture that is bifurcated and has two arcuate slots, each slot receiving part of the spring element, and the part of the aperture that accommodates the spring element, is of a generally arcuate outwardly directed part of the periphery of the aperture.

Preferably, the anti-backlash gears are held in position by a retaining washer.

The present invention seeks to provide an improved gear, the gear being such that it can be incorporated into a steering wheel arrangement of the type described above to improve the “feel” of the steering wheel. Of course, the gear arrangement may find many other applications.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, an embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a partly perspective and partly cutaway view of a steering wheel arrangement;

FIG. 2 is a sectional view illustrating part of the steering wheel mounting in more detail.

FIG. 3 is a section view taken through the line 3-3 of FIG. 2;

FIG. 4 is a perspective view of a pinion unit;

FIG. 5 is an exploded view illustrating two anti-backlash gears, a washer and a spring;

FIG. 6 is a plan view of one anti-backlash gear;

FIG. 7 is a perspective view of a washer;

FIG. 8 is a view of a spring unit;

FIG. 9 is a sectional view of the pinion.

Referring initially to FIGS. 1-3 of the accompanying drawings a steering wheel assembly 1 incorporates a steering wheel 2 which is mounted on a steering column 3. A fixed housing 4 is provided which is securely mounted in position.

The steering wheel 2 incorporates a metallic frame 5 which defines spokes such as the spoke 6, and a peripheral rim 7. The frame 5 is covered with an appropriate outer covering 8, for example, of a foam material.

The frame 5 is mounted by means an annular bearing 9 on an appropriate formation provided on the housing 4. The steering wheel is to rotate about a predetermined axis. An air-bag unit 10 may be provided, connected directly to the fixed element 4. The air-bag unit will thus not rotate on rotation of the steering wheel. The air-bag unit may be provided with a plurality of operating buttons 11 or the like, which will be fixed in position.

Part of the frame 5 adjacent the annular bearing 9 defines an inwardly facing ring gear 12.

The steering column 3 is mounted within a tubular projection 13 extending downwardly from the rest of the fixed housing 4 by means of two spaced apart bearings 14, 15 (FIG. 1). The uppermost end of the steering column carries a pinion 16, the pinion 16 having a toothed periphery 17 which engages with the ring gear 12 provided on the steering wheel frame.

It will be understood that on rotation of the steering wheel, the pinion 16 will rotate, thus rotating the steering column. A steering wheel assembly of this general type has been proposed before, and is described in EP-A-1199243.

However, in the present embodiment of the invention the pinion 16 is provided with anti-backlash gears as will now be described.

FIG. 4 is a perspective view of the pinion 16. The pinion 16 is provided with a depending portion to be connected to the steering column and has a disc-like portion provided with a peripheral toothed gear 17. Mounted on top of the disc-like portion are anti-backlash gears 18,19, which are superimposed by a mounting washer 20.

FIG. 6 illustrates one of the anti-backlash gears 18 in more detail. However, both anti-backlash gears 18, 19 are identical. However, one of the backlash gears is inverted relative to the other, so that one gear is one way up, and the other is effectively upside down. The anti-backlash gear 18 is in the form of a relatively thin plate. The plate has a toothed outer periphery 21.

The toothing of the outer periphery 21 is identical to the toothing 17 of the pinion gear 16 itself. The toothing on the anti-backlash gear 18 may, in some embodiments, have teeth which are slightly shorter than the teeth on the pinion gear 16, but there should be the same number of teeth on the anti-backlash gears 18, 19 as on the pinion gear 16, with the same basic width of tooth and width of gap between adjacent teeth.

The centre of the anti-backlash gear 18,19 is provided with an aperture 22 having an irregularly shaped periphery. The periphery of the aperture 22 is provided with three equi-angularly spaced arcuate outwardly projecting recesses 23. Offset and again equi-angularly spaced, and thus located between the arcuate projecting recesses 23, are further projecting recesses 24, each of the projecting recesses 24 being bifurcated to present two arcuate outwardly extending slots 25, 26.

FIG. 7 illustrates the mounting washer 20 in more detail. The washer 20 comprises a substantially flat disc 27 provided with a plurality of apertures 28 therein. The centre of the washer defines an aperture 29 surrounded by an upstanding collar 30.

FIG. 8 illustrates a spring element 31, a plurality of which are used to bias the anti-backlash gears 18, 19 relative to the pinion 16. Each spring element 31 is formed from a sheet spring material, the element having a semi-circular or “C” cross-section and having a predetermined length.

Each spring element 31 is dimensioned so that it may be inserted into a respective bifurcated recess 24 formed in the outer periphery of the aperture 22, with the two opposed sides of the spring element 31 being received in the two arcuate slits 25, 26. Each bifurcated recess 24 will thus retain a respective spring element 31 substantially in position. Also, each spring element 31 is designed so that it may be received within an arcuate recess, such as the arcuate recess 23, with opposed sides of the spring engaging opposed sides of the recess.

It is to be appreciated that the two anti-backlash gears 18, 19 are initially located in position one above the other, with the arcuate recesses 23 of one gear being aligned with the bifurcated recess 24 of the other gear, and vice-versa. One gear is upside down relative to the other. A plurality of spring elements 31 may then be located in position, and a maximum of six spring elements may be used in the described embodiment, with each spring element passing through a co-aligned pair of recesses 23,24 in the adjacent anti-backlash gears 18,19. The spring elements 31 are such that the anti-backlash gears 18,19 are held in the superimposed position, but can move, rotationally, relative to each other, whilst compressing the spring elements 31.

It is to be noted that the anti-backlash gears, when superimposed, are relatively located so that the teeth of the two anti-backlash gears are slightly offset from each other.

As can be seen from FIGS. 4 and 9, the two anti-backlash gears 18,19 are mounted on top of the pinion gear 16. The spring elements 31 have projecting ends received within an appropriate recess 32 formed in the pinion gear 16. The washer 20 overlies the anti-backlash gears 18,19 and serves to retain the anti-backlash gears in position on the pinion 16.

When the anti-backlash gears 18,19 have been mounted on the pinion gear, the teeth of the anti-backlash gears are located so that they are displaced to each side of the corresponding tooth 17 on the pinion gear 16. Thus, when the pinion gear 16 is brought into contact with the ring gear 12, the two anti-backlash gears 18, 19 will have to move relative to each other so that the teeth on all three gears are co-aligned in order to be received between a single pair of adjacent teeth on the ring gear 12. When the pinion gear 16 and the backlash gas 18, 19 are released from this condition, the backlash gears 18,19 will be biased apart by the spring elements 31. Thus, the anti-backlash gears will firmly engage the ring gear 12, there being no “play” or backlash between the ring gear 12 and the pinion gear 16.

Consequently the steering wheel will have a good “feel” when the steering wheel is in use.

It is to be appreciated that whilst, in the described embodiment, two anti-backlash gears are provided which are biased in opposite directions relative to the pinion gear, an adequate effect may be obtained by providing a single backlash gear on the pinion, with that single gear being resiliently biased relative to the pinion.

Again, whilst the invention has been described with reference to an embodiment in which the anti-backlash gears are provided on the pinion, one or more anti-backlash gear elements might be provided on the ring gear. Of course, in such a situation the anti-backlash gears would each be of ring-gear form and the pinion would have to be dimensioned to engage not only with the ring gear, but also with the anti-backlash gears.

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.

Claims

1. A steering-wheel arrangement comprising: a steering wheel having a first gear element; and a second gear element mounted on or mountable on a steering column; the first and second gear elements inter-engaging one another; the arrangement further comprising at least one anti-backlash gear mounted on one of said gear elements, the or each anti-backlash gear having teeth configured so as to align substantially with the teeth of said gear element upon which it is mounted, the anti-backlash gear being rotatably biased, relative to the gear element upon which it is mounted, towards a position in which the teeth of the anti-backlash gear are displaced from the corresponding teeth of the gear element.

2. A steering wheel arrangement according to claim 1, wherein two said antibacklash gears are mounted on said gear element, the two anti-backlash gears being biased in opposite directions.

3. A steering wheel arrangement according to claim 1, wherein said gear element on which the or each anti-backlash gear is mounted is a ring gear.

4. A steering wheel arrangement according to claim 1, wherein said gear element on which the or each anti-backlash gear is mounted is a pinion gear.

5. A steering-wheel arrangement according to claim 4, wherein the pinion gear is provided with two anti-backlash gears, the anti-backlash gears each being in the form of a plate, each plate having an aperture therein, the aperture defining portions to engage spring elements, the apertures of the two anti-backlash gears being coaligned and receiving spring elements.

6. A steering-wheel arrangement according to claim 5, wherein each spring element is of substantially “C” shape, each spring element passing through part of the aperture in one plate which engages the spring element and part of the aperture in the other spring plate which accommodates the spring element.

7. A steering-wheel arrangement according to claim 6, wherein part of the aperture that engages the spring element is an outwardly directed part of the aperture that is bifurcated and has two arcuate slots, each slot receiving part of the spring element, and the part of the aperture that accommodates the spring element, is of a generally arcuate outwardly directed park of the periphery of the aperture.

8. A steering-wheel arrangement according to claim 4, wherein the anti-backlash gears are held in position by a retaining washer.

9. A steering-wheel arrangement comprising: a steering wheel having a first gear element; and a second gear element mounted on or mountable on a steering column; one of said gear elements being a pinion gear; the first and second gear elements inter-engaging one another; the arrangement further comprising two antibacklash gears mounted on one of said gear elements, with the said gear element on which the anti-backlash gears are mounted being a pinion gear, each antibacklash gear having teeth configured so as to align substantially with the teeth of said gear element upon which it is mounted, the anti-backlash gear being rotatably biased, relative to the gear element upon which it is mounted, towards a position in which the teeth of the anti-backlash gear are displaced from the corresponding teeth of the gear element, the anti-backlash gears each being in the form of a plate, each plate having an aperture therein, the aperture defining portions to engage spring elements, the apertures of the two anti-backlash gears being co-aligned and receiving spring elements of substantially “C” shape, each spring element passing through part of the aperture in one plate which engages the spring element and part of the aperture in the other spring plate which accommodates the spring element, the part of the aperture that engages the spring element being an outwardly directed part of the aperture that is bifurcated and has two arcuate slots, each slot receiving part of the spring element, and the park of the aperture that accommodates the spring element being of a generally arcuate outwardly directed part of the periphery of the aperture.