GB2570674A - A method of assembling an anti-backlash gear and an anti-backlash gear - Google Patents

Abstract

The method comprises positioning a protrusion 107 of a second gear 102 within an axial bore 105 of a first gear 101, to form a passageway 1001 that extends around the protrusion. A first hole 406, which extends through the first gear from the passageway is aligned with a second hole (711 fig. 14), which extends through the second gear 102 from the passageway. A first end 1101 of a spring member 110 is passed through an opening (407 fig. 11) of the first hole and into the second hole. One of the first gear and the second gear is rotated with respect to the other to cause a portion (1312 fig. 13) of the spring member to extend along the passageway from the first hole to the second hole. The multi-part gear may be used to take up slack and reduce backlash when the anti-backlash gear is in mesh with another gear by the spring member urging the teeth of the first gear against one side of the teeth of the other gear and urging the teeth on the second gear against the other side of the teeth of the other gear.

Description

TECHNICAL FIELD

The present disclosure relates to a method of assembling an anti-backlash gear and an antibacklash gear. In particular, but not exclusively it relates to a method of assembling an antibacklash gear and an anti-backlash gear for use in a vehicle.

Aspects of the invention relate to a method, an anti-backlash gear, a gear arrangement, an anti-roll bar, an engine, a transmission, and a vehicle.

BACKGROUND

When one gear is arranged to mesh with another gear, a clearance, referred to as backlash, is provided between mating gear teeth to prevent the gears from binding. However, the backlash has disadvantages, such as increased noise and inaccuracies in output motion. To avoid disadvantages of backlash, anti-backlash gears have been designed to eliminate backlash. Such anti-backlash gears comprise two coaxially mounted gears and one or more springs. A first one of the gears is rotatable with respect to the second one of the gears about their common axis, and the spring resiliently biases the first gear with respect to the second gear. In use, when the anti-backlash gear is arranged to engage another gear, the teeth of the first gear are forced against one side of the teeth of the other gear and the teeth of the second gear are forced against the other side of the teeth of the other gear. Consequently, the teeth of the anti-backlash gear are able to remain in contact with the teeth of the other gear even when there is a reverse in the rotational direction of the gears.

Disadvantages of existing anti-backlash gears include complexity or the components and/or the assembly of the components, and also the need to have an additional means to hold the first and second gears of the anti-backlash gear together.

It is an aim of the present invention to address disadvantages of the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provided a method, an anti-backlash gear, a gear arrangement, an anti-roll bar and a vehicle as claimed in the appended claims.

According to an aspect of the invention there is provided a method of assembling an antibacklash gear comprising: positioning a protrusion of a second gear within an axial bore of a first gear to form a passageway that extends around the protrusion, the passageway being defined by a first surface of the first gear and a second surface of the second gear; aligning a first hole, which extends through the first gear from the passageway, with a second hole, which extends through the second gear from the passageway; passing a first end of a spring member through an opening of the first hole and through the first hole into the second hole, or passing a first end of a spring member through an opening of the second hole and through the second hole into the first hole; and rotating one of the first gear and the second gear with respect to the other one of the first gear and the second gear to cause a portion of the spring member to extend along the passageway from the first hole to the second hole.

This provides the advantage that the gears may be of a relatively simple design and the method is relatively easy to perform.

In some embodiments the method comprises providing a stopping means to prevent movement of the spring member into the opening of the first hole and/or providing a stopping means to prevent movement of the spring member into the opening of the second hole.

In some embodiments, providing the stopping means comprises at least one of: affixing an end portion of the spring member to an exterior surface of the first gear or the second gear; bending an end portion of the spring member to prevent the end portion from passing through the opening.

This provides the advantage of a simple method of preventing further movement of the spring member into the first and/or second hole to enable the spring member to be tensioned.

In some embodiments the method comprises further rotating the first gear or the second gear to cause elastic deformation of a section of the spring member.

In some embodiments the spring member comprises a wire or a strip of resilient material and said further rotating of the first gear or the second gear causes a decrease in a radius of curvature of the spring member around a corner of the protrusion. The material may comprise a metal, a composite or a plastics material.

In some embodiments the first hole and/or the second hole extend in a direction having a radial component.

In some embodiments the first hole and/or the second hole extend in a direction having an axial component.

In some embodiments the first surface of the first gear comprises a groove in an interior surface defining the axial bore, and/or the second surface of the second gear comprises a groove on a peripheral surface of the protrusion.

In some embodiments the first surface of the first gear comprises a groove in an interior surface defining the axial bore, and the second surface of the second gear comprises a groove on a peripheral surface of the protrusion, and the method comprises positioning the groove in the interior surface alongside the groove in the peripheral surface to form the passageway.

This provides the advantage that when the spring member extends through the passageway it holds the first gear and the second gear together.

In some embodiments the method comprises temporarily locating a former against a region of the peripheral surface to support the spring member during said rotating.

This provides the advantage that the likelihood of the spring member being strained during the rotating is reduced.

According to another aspect of the invention there is provided an anti-backlash gear comprising a first gear, a second gear and a spring member resiliently deformable by rotation of one of the first gear and the second gear with respect to the other one of the first gear and the second gear, wherein: the first gear comprises an axial bore defined by an interior surface extending circumferentially around the axial bore; the second gear comprises a protrusion having a peripheral surface, the protrusion being configured to rotate within the axial bore with at least a portion of the peripheral surface extending circumferentially alongside the interior surface of the first gear; a passageway extending around the protrusion, the passageway being defined by a surface of the first gear and a surface of the second gear; the first gear defines a first hole extending from the passageway; the second gear defines a second hole extending from the passageway; the spring member comprises a first portion extending along the first hole, a second portion extending along the passageway, and a third portion extending along the second hole; and the first hole extends to an exterior surface of the first gear, and/or the second hole extends to an exterior surface of the second gear.

This provides the advantage that the anti-backlash gear has a relatively simple construction and is easy to assemble.

In some embodiments the first hole extends to the exterior surface of the first gear in a direction having a radial component.

In some embodiments the first hole extends to the exterior surface of the first gear and the exterior surface defines teeth of the first gear.

In some embodiments the first hole extends to an opening between two teeth of the first gear. This provides the advantage that an end portion of the spring member may be positioned between the two teeth so that it does not affect the ability of the anti-backlash gear to mesh with another gear. It also enables the spring member to be easily fed through the first hole into the second hole during assembly when the passageway is defined by a groove in both the interior surface of the first gear and the peripheral surface of the second gear.

In some embodiments the first hole extends to the exterior surface of the first gear in an axial direction or a direction having an axial component. This provides the advantage that it enables the spring member to be easily fed through the first hole into the second hole during assembly when the passageway is defined by a groove in both the interior surface of the first gear and the peripheral surface of the second gear.

In some embodiments the second hole is a blind hole.

In some embodiments the second hole extends in a radial direction or a direction having a radial component.

In some embodiments the second hole extends in an axial direction or a direction having an axial component to the exterior surface of the second gear.

In some embodiments the second portion of the spring member has a cross-sectional shape and the first portion and/or the third portion have the same cross-sectional shape as the second portion. This provides the advantage that the spring member may be a simple structure such as a wire. In alternative embodiments, the second portion of the spring member has a cross-sectional shape and the first portion and/or the third portion have different cross-sectional shapes, or different diameters, to the second portion.

In some embodiments the spring member comprises a wire or a strip formed of a resilient material. The material may comprise a metal, a composite or a plastics material.

In some embodiments the protrusion has at least a first part that holds a first section of the spring member at least a first distance from a central axis of the axial bore; a region of the peripheral surface is disposed between a second section of the spring member and the central axis; all distances from the central axis to the region of the peripheral surface are less than the first distance; and the second section of the spring member is elastically deflectable towards the region by rotation of one of the first gear and the second gear with respect to the other one of the first gear and the second gear.

This provides the advantage that the first gear may be biased to rotate with respect to the second gear by flexing of the spring member in a similar manner to a leaf spring.

In some embodiments the protrusion holds a third section of the spring member at least the first distance from the central axis, and the second section extends between the first section and the third section.

In some embodiments the region is flat. This provides the advantage that it provides the protrusion with a simple shape that is easily produced.

In some embodiments a cross-section of the protrusion is defined by: the region of the peripheral surface; an arc of a circle; and corners between the region and the arc, which have a smaller radius of curvature than the arc. This provides the advantage that the curved corners provide support for the spring member at positions when it is most tightly bent.

In some embodiments the spring member holds the first gear and the second gear together.

This provides the advantage that no additional means is required to hold the first gear and the second gear together.

In some embodiments the spring member is configured to resiliently bias one of the first gear and the second gear with respect to the other one of the first gear and the second gear.

In some embodiments the passageway is defined at least in part by a groove in the interior surface and/or a groove in the peripheral surface.

In some embodiments the passageway is defined at least in part by a groove in the interior surface and a groove in the peripheral surface. This provides the advantage that the presence of the spring member in the passageway holds the first and second gears together.

In some embodiments the anti-backlash gear comprises a stopping means to prevent movement of the spring member into the opening of the first hole and/or a stopping means to prevent movement of the spring member into the opening of the second hole. The stopping means may comprise at least one of: an end portion of the spring member affixed to an exterior surface of the first gear or the second gear; a bend in an end portion of the spring member.

According to a further aspect of the invention there is provided a gear arrangement comprising the anti-backlash gear according to any one of the previous paragraphs and at least one other gear engaged with the anti-backlash gear, wherein the second section of the spring member is elastically deflected away from the interior surface towards the region to cause teeth of the first gear to be urged against one side of teeth of the at least one other gear, and teeth of the second gear to be urged against the other side of the teeth of the at least one other gear.

According to yet another aspect of the invention there is provided an anti-roll bar comprising an electric motor and a reduction gear arrangement, in which the reduction gear arrangement includes the anti-backlash gear of any one of the previous paragraphs.

According to a still further aspect of the invention there is provided a vehicle comprising an anti-backlash gear according to any one of the previous paragraphs, a gear arrangement according to a previous paragraph and/or an anti-roll bar according to the previous paragraph.

According to yet another aspect of the invention there is provided an engine comprising an anti-backlash gear according to any one of the previous paragraphs.

According to yet another aspect of the invention there is provided a transmission for a vehicle comprising an anti-backlash gear according to any one of the previous paragraphs.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 shows an anti-backlash gear embodying the present invention;

Figs. 2, 3 and 4 show a front view, a bottom view and a cross-sectional side view of a first gear;

Figs. 5, 6 and 7 show a front view, a bottom view and a cross-sectional side view of a second gear;

Figs. 8, 9 and 10 show a front view, a bottom view and a cross-sectional side view of an assembly comprising the first and second gear;

Figs. 11 to 14 show the assembly of Fig. 8 and a spring member in cross-sectional front views at subsequent stages of a method of assembling the anti-backlash gear of Fig. 1;

Fig. 15 shows a gear arrangement comprising the anti-backlash gear of Fig. 1 and another gear;

Fig. 16 shows a cross-sectional side view of the anti-backlash gear of Fig. 1;

Fig. 17 shows a front view of an alternative assembly comprising a first gear and a second gear;

Fig. 18 shows an anti-backlash gear embodying the present invention that is formed from the assembly shown in Fig. 17;

Figs. 19 and 20 show a front view and a cross-sectional view of an assembly comprising a first gear and a second gear of another anti-backlash gear embodying the present invention;

Figs. 21 to 24 show a method of assembling an anti-backlash gear from the assembly of Figs. 19 and 20;

Figs. 25 and 26 show a front view and a cross-sectional side view of an assembly comprising a first gear and a second gear of yet another anti-backlash gear embodying the present invention;

Fig. 27 shows the anti-backlash gear comprising the assembly shown in Figs 25 and 26; and Fig. 28 shows a vehicle embodying the present invention, comprising anti-roll bars incorporating an anti-backlash gear.

DETAILED DESCRIPTION

An anti-backlash gear 100 embodying the present invention is shown in Fig. 1. The antibacklash gear 100 comprises a first gear 101, a second gear 102. The first gear 101 and the second gear 102 have teeth 103 arranged cylindrically around a central axis 104. The first gear 101 comprises an axial bore 105 defined by an interior surface 106 extending circumferentially around the axial bore 105. In the present embodiment the interior surface 106 of the first gear 101 is generally cylindrical and extends symmetrically around the central axis 104.

The second gear 102 comprises a protrusion 107 having a peripheral surface 108. The protrusion 107 is configured to rotate within the axial bore 105 with at least a first region 109 of the peripheral surface 108 extending circumferentially alongside the interior surface 106 of the first gear 101. The first region 109 of the peripheral surface 108 extends more than 180 degrees around the central axis 104, so that the first gear 101 is able to rotate about the protrusion 107 but radial movement of the first gear 101 relative to the second gear 102 is prevented. In alternative embodiments, several separate regions of the peripheral surface 108 are arranged to extend alongside the interior surface 106 defining the axial bore 105, and the several separate regions extend more than 180 degrees around the central axis, so that the first gear 101 is able to rotate about the protrusion 107 but radial movement of the first gear 101 relative to the second gear 102 is prevented.

The anti-backlash gear 100 also comprises a spring member 110 resiliently deformable by rotation of one of the gears 101 and 102 with respect to the other one of the gears 101 and 102. The spring member 110 is configured to resiliently bias one of the first gear 101 and the second gear 102 with respect to the other one of the first gear 101 and the second gear 102, in use.

The first gear 101 is shown in a front view in Fig. 2, a bottom view in Fig. 3 and a crosssectional side view in Fig. 4. The first gear 101 has a first end face 401 and a second end face 402 that are connected at their peripheries by a toothed surface 403 comprising the teeth 103. When the first gear 101 is assembled with the second gear 102, the first end face 401 faces the second gear 102, but the second end face 402 and the toothed surface 403 provide parts of an exterior surface 404 that is not covered by the second gear 102.

The first end face 401 and a second end face 402 are also connected by the interior surface 106, which defines the axial bore 105. An annular groove 405 in the interior surface 106 also extends symmetrically about the central axis 104. In the present embodiment, the groove 405 has rectangular cross-section as illustrated in Fig. 4, but in alternative embodiments it may have another shape of cross-section, such as a semicircular cross-section, or oblong with a semicircular bottom.

A first hole 406 extends from the groove 405 to the exterior surface 404. In the present embodiment, the first hole 406 extends radially outwards from the groove 405 to the toothed surface 403. An opening 407 of the first hole 406 is disposed between two teeth 103, and in the present embodiment a recess 408 is provided between the two teeth adjacent to the opening 407. The recess 408 is provided to receive an end portion of the spring member 110 as will be described below.

The second gear 102 is shown in a front view in Fig. 5, a bottom view in Fig. 6 and a crosssectional side view in Fig. 7. The second gear 102 has main body 700 that has a first end face 701 and a second end face 702 that are connected at their peripheries by a toothed surface 703 comprising the teeth 103. When the second gear 102 is assembled with the first gear 101, the first end face 701 faces the first gear 101, but the second end face 702 and the toothed surface 703 provide parts of an exterior surface 704 that is not covered by the first gear 101.

The protrusion 107 extends from the first face 701 of the main body 700. The peripheral surface 108 of the protrusion 107 has a second region 705 that meets the cylindrically extending first region 109 at a first corner 706 and a second corner 707. In the present embodiment, the second region 705 and the two corners 706 and 707 extend parallel to the central axis 104, but in alternative embodiments the two corners 706 and 707 are not parallel to each other. Also, in the present embodiment, the corners 706 and 707 are edges separating the first region 109 and the second region 705, but as will be described below with reference to Figs. 17 and 18, the corners 706 and 707 may comprise curved surfaces or chamfers. The first region 109 of the peripheral surface 108 has a small radius of curvature when compared to the second region 705, and consequently the whole of the second region 705 is closer to the central axis than the first region 109. In the present embodiment, the 10 second region 705 is flat, but in alternative embodiments it may be curved, as described below with reference to Figs. 17 and 18.

In the present embodiment, the peripheral surface 108 of the protrusion 107 comprises an annular groove 710. The groove 710 extends circumferentially around the protrusion 107 along the first region 109 of the peripheral surface 108. The groove 710 is positioned on the protrusion 107 so that when the protrusion 107 is located within the axial bore 105 of the first gear 101, the groove 710 may be positioned alongside the groove 405 in the interior surface 106 of the first gear 101 to form a passageway (1001 shown in Figs. 8 and 10).

A second hole 711 extends from the groove 710 into the protrusion 107. In the present embodiment, the second hole 711 extends radially inwards, but in alternative embodiments it extends in other directions as will be described below.

In the present embodiment, the second region 705 extends from the first face 701 of the second gear 102 to an end face 708 of the protrusion 107. However, in alternative embodiments, the cylindrically extending first region 109 of the peripheral surface 108 extends the whole way around the protrusion 107 at one or more positions along the central axis 104. For example, as illustrated in dotted outlines 709 in Figs. 5 and 7, the first region 109 may extend cylindrically the whole way around the protrusion 107 adjacent to the first end face 701 of the main body 700 of the first gear 101 and adjacent to the end face 708 of the protrusion 107. However, in such embodiments, the peripheral surface 108 of the protrusion 107 is still provided with a second region 705 having a large radius of curvature (when compared to the first region 109) at axial positions 712 that coincide with the groove 710 of the second gear 102 and the groove 405 of the first gear 101.

A method of assembling the anti-backlash gear 100 will now be described with reference to Figs. 8 to 14. Firstly, the first gear 101 and the second gear 102 are assembled together to form the assembly 801 shown in Figs. 8 to 10. The assembly 801 is shown in a front view in Fig. 8, in a bottom view in Fig. 9 and a cross-sectional side view in Fig. 10. To assemble the first gear 101 and second gear 102 together, the protrusion 107 of the second gear 102 is slid inside the axial bore 105 of the first gear 101 until the groove 710 in the protrusion 107 is alongside the groove 405 in the interior surface 106 of the first gear 101. The cylindrically extending first region 109 of the peripheral surface 108 of the protrusion 107 has a radius of curvature that is marginally smaller than the radius of the axial bore 105 to enable the first gear 101 to be mounted on the second gear 102 in this way. If the first hole 406 and second hole 711 are not already aligned, the first gear 101 may be rotated with respect to the second gear 102, to align the first hole 406 with the second hole 711.

When the first gear 101 and the second gear 102 have been assembled together, the grooves 405 and 710, which are positioned alongside each other, form an enclosed passageway 1001 extending around the protrusion 107.

It may also be noted that the interior surface 106 of the first gear 101, the first region 109 of the peripheral surface 108 of the protrusion 107 of the second gear 102, and the toothed surfaces 403 and 703 of the first gear 101 and the second gear 102 are coaxially arranged.

In alternative embodiments, a groove 405 may only be provided on the interior surface 106 of the first gear 101 and not on the protrusion 107 of the second gear 102, or alternatively a groove 710 may only be provided on the protrusion 107 and not on the interior surface 106 of the first gear 101. In a further alternative embodiment, a passageway 1001 is formed between an interior surface 106 of a first gear and a protrusion 107 of a second gear between steps formed in the interior surface 106 and the peripheral surface 108 of the protrusion 107. However, in each of the various embodiments, a passageway 1001 is formed between a first surface of the first gear 101, such as the interior surface 106, and a second surface of the second gear 102, such as the peripheral surface 108.

Figs. 11 to 14 show the assembly 801 and the spring member 110 in cross-sectional front views at subsequent stages of the method of assembling the anti-backlash gear 100.

In the present embodiment, the spring member 110 comprises a length of spring steel in the form of a wire. Alternatively, the spring member 110 may comprise an alternative resilient metal, or a plastics material, or a composite material, and it may be in the form of a strip having a non-circular cross-section.

A first end 1101 of the spring member 110 is positioned outside of the opening 407 of the first hole 406 formed in the first gear 101, as shown in Fig. 11. The first end 1101 is then passed through the opening 407 of the first hole 406 formed in the first gear 101 and through the first hole 406 into the second hole 711 formed in the second gear 102, as shown in Fig. 12.

One of the gears 101, 102 is then rotated with respect to the other gear 101, 102 while the spring member 110 continues to be fed into the first hole 406. The rotation causes a bend 1300 (shown in Fig. 13) to be formed in the spring member 110 where it enters the second hole 711 in the protrusion 107, and the bend 1300 prevents movement of the first end 1101 of the spring member 110 back along the second hole 711. The rotation also causes a portion of the spring member 110 to be drawn into the passageway 1001 and wrapped around the protrusion 107. The rotation causes a first section 1301 (shown in Fig. 13) of the spring member 110 to be positioned around a first part 1202 (shown in Fig. 12) of the protrusion 107 along the groove 710, causes a second section 1302 (shown in Fig. 13) of the spring member 110 to be positioned around the protrusion 107 across the second region 705, and causes a third section 1303 (shown in Fig. 13) of the spring member 110 to be positioned around a second part 1203 (shown in Fig. 12) of the protrusion 107 along of the groove 710. Fig. 13 shows the assembly comprising the first gear 101, the second gear 102 and the spring member 110 after completion of this initial rotation. Typically, the second gear 102 is rotated with respect to the first gear 101 by 270 degrees in this initial rotation.

Before the initial rotation is performed, a former 1201 may be located against the second region 705 of the peripheral surface 108 of the protrusion 107, as shown in Figs. 12 and 13, to ensure that the second section 1302 of the spring member 110 is held within the groove 405 of the interior surface 106 of the first gear 101 during the initial rotation. By supporting the spring member 110 with the former 1201 during this initial rotation, the likelihood of the spring member 110 being strained is reduced.

After the initial rotation has been completed, a stopping means is provided to prevent further movement of the spring member 110 into the opening 407 of the first hole 406. Providing the stopping means may comprise affixing an end portion 1304 of the spring member 110 to an exterior surface 404 of the first gear 101, or bending an end portion 1304 of the spring member 110 to prevent the end portion 1304 from passing through the opening 407. For example, the end portion 1304 of the spring member 110 that outside of the first hole 406 may be cut to a required length and bent over and concealed within the recess 408 (shown in Fig. 4) between teeth 103 of the first gear 101. The end portion 1304 is shown after 13 bending in this way in Fig. 1 and Fig. 16. Typically, the spring member 110 is made to the required length and bent prior to assembly.

Other alternative stopping means for preventing further movement of the spring member 110 into the first hole 406 may be provided. For example, instead of attachment of the end portion 1304 to the exterior surface 404 or a bend in the end portion 1304, the stopping means may comprise a ferrule crimped onto the spring member 110 that is located within a counterbore of the first hole 406. In alternative embodiments, a wedge may be forced into the hole alongside the spring member 110, or the first hole may be deformed to provide the stopping means.

After providing the stopping means to prevent further movement of the spring member 110 into the first hole 406, the former 1201 (if used) is removed. The anti-backlash gear 100 is then complete.

As shown in Fig. 13, a first portion 1311 of the spring member 110 resides in the first hole 406 in the first gear 101, a second portion 1312 of the spring member 110 extends between the first hole 406 and the second hole 711 in the second gear 102, and a third portion 1313 of the spring member 110 resides within the second hole 711. The second portion 1312 of the spring member 110 comprises the first section 1301 and the third section 1303, which extend over the first region 109 of the peripheral surface 108, and the second section 1302, which extends across the second region 705 of the peripheral surface 108.

In the present embodiment the second portion 1312 of the spring member 110 has the same cross-sectional shape as the first portion 1311 and the third portion 1313. This enables the first hole 406, the passageway 1001 and the second hole 711 to be dimensioned to enable the first portion 1311 of the spring member 110 to pass through the first hole 406 and the passageway 1001 and to enable the first portion 1311 be retained in the second hole 711. However, in alternative embodiments, at least a part of the third portion 1313 of the spring member 110 may be provided with a smaller diameter than the second portion 1312, and the second hole 711 may be dimensioned so that the third portion 1313 is a good fit in the second hole 711. In addition, or alternatively, at least a part of the first portion 1311 may have a larger diameter than the second portion 1312, and a corresponding part of the first hole 406 may have a counterbore to receive the larger diameter. For example, such an 14 arrangement may provide a stopping means for preventing the further movement of the spring member through the first hole 406.

When the anti-backlash gear 100 is to be used, one of the first gear 101 and the second gear 102 is further rotated with respect to the other one of the first gear 101 and the second gear 102. The anti-backlash gear 100 is shown in Fig. 14 after further rotation of the second gear 102 with respect to the first gear 101.

The further rotation causes the second corner 707 of the protrusion 107 to ride over the spring member 110 so that a longer section of the spring member 110, is enclosed in the passageway 1001 between the first hole 406 and the second corner 707. Consequently, while the first section 1301 is spaced from the central axis 104 by the first part 1202 of the protrusion 107 and the third section 1303 is spaced from the central axis 104 (shown in Fig. 1) by the second part 1203 of the protrusion 107, the second section 1302 of the spring member 110, which extends across the second region 705 of the peripheral surface 108 of the protrusion 107, is shortened and pulled towards the second region 705. This causes the spring member 110 to be further elastically deformed as the radiuses of curvature of the spring member 110 around the corners 706 and 707 of the protrusion are decreased. Therefore, the resilience of the spring member 110 resists the further rotation and urges the second gear 102 to rotate back towards the position shown in Fig. 13.

With the spring member 110 flexed by this further rotation of the first gear 101 with respect to the second gear 102, the anti-backlash gear 100 may be installed in a gear arrangement. A gear arrangement comprising the anti-backlash gear 100 and another gear 1501 is shown in Fig. 15. As mention above, the resilience of the spring member 110 urges the second gear 102 to rotate with respect to the first gear 101. Consequently, one of the teeth 103 of the first gear 101 is urged against one side of a tooth 1503 of the other gear 1501, and one of the teeth 103 of the second gear 102 is urged against the other side of the tooth 1503 of the other gear 1501. In general, as the anti-backlash gear 100 and the other gear 1501 rotate, the teeth 103 of the first gear 101 are urged against one side of the teeth 1503 of the other gear 1501, and teeth 103 of the second gear 102 are urged against the other side of the teeth 1503 of the other gear 1501 to eliminate backlash.

A cross-sectional side view of the anti-backlash gear 100 is shown in Fig. 16. Fig. 16 illustrates how the spring member 110 holds the first gear 101 and the second gear together. The cross-section of the spring member 110 in the passageway 1001 extends into both the groove 405 in the interior surface 106 of the first gear 101 and the groove 710 in the peripheral surface 108 of the protrusion 107. The cross-section of the spring member 110 is configured such that it cannot fit into only one of the grooves 405 and 710, and therefore the presence of the spring member 110 prevents the first gear 101 from moving along the central axis 104 relative to the second gear 102.

A front view of an alternative assembly 1701 comprising a first gear 101A and a second gear 102A is shown in Fig. 17 and an anti-backlash gear 100A embodying the present invention that is formed from the assembly 1701 is shown in Fig. 18. The anti-backlash gear 100A is like the anti-backlash gear 100 of Fig. 1, except for the features described below.

Firstly, the first hole 406 in the first gear 101A and the second hole 711 in the second gear 102A do not extend radially. Instead, the first hole 406 and the second hole 711 extend in a direction that has a radial component but which does not intersect the central axis 104 (which extends into the page in Figs. 17 and 18). However, like those of the anti-backlash gear 100 of Fig. 1, the first hole 406 and the second hole 711 are configured to align, as shown in Fig. 17 so that the spring member 110 may be passed through the first hole 406 and into the second hole 711.

Secondly, the second region 705 of the peripheral surface 108 is curved and convex. Consequently the area of cross-section of the protrusion 107 may be larger than it might be if the second region 705 were flat. However, the whole of the second region 705, across which the spring member 110 extends, is closer to the central axis 104 than the first region 109 of the peripheral surface 108 that extends circumferentially alongside the interior surface 106 of the first gear 101 A, and therefore the second section 1302 of the spring member 110 has space in which to flex when the first gear 101A is rotated relative to the second gear 102A.

Thirdly, the protrusion 107 has rounded corners 1706 and 1707 between the second region 705 of its peripheral surface 108 and the groove 710 in the first region 109 of the peripheral surface 108. Therefore, a cross-section of the protrusion 107 at the location of the groove 16

710 and perpendicular to the central axis 104 is defined by the second region 705 of the peripheral surface 108, an arc of a circle along the bottom of the groove 710, and the corners 1706 and 1707 between the second region 705 and the arc. The corners 1706 and 1707 have a smaller radius of curvature than the arc and the corners 1706 and 1707 and the arc form a continuous smooth curve. This arrangement of curved corners provides support for the spring member 110 and prevents it from being overly stressed as it bends at the corners 1706 and 1707.

Fourthly, the second gear 102A is also provided with an axial bore 1708 for receiving a shaft (not shown).

It will be understood that each of these four features may be applied together or individually to the anti-backlash gear 100 of Fig. 1.

A first gear 101B and a second gear 102B of another anti-backlash gear embodying the present invention are shown assembled together in a front view in Fig. 19 and a crosssectional view in Fig. 20. The position of the cross-section of Fig. 20 is identified by line A-A in Fig. 19. The first gear 101B and the second gear 102B are like the first gear 101 and second gear 102 of the anti-backlash gear of Fig. 1, but differ in the following ways.

Firstly, the protrusion 107 does not have a groove that forms a part of its passageway 1001. The passageway 1001 of anti-backlash gear 100B is defined by an annular groove 405 in the interior surface 106 of the first gear 101B and the first region 109 of the peripheral surface 108 of the protrusion 107, which is free of grooves.

Secondly, the first hole 406 in the first gear 101B and the second hole 711 in the second gear 102B do not extend in a radial direction but instead extend in directions that have radial, axial and circumferential components.

Thirdly, both the first hole 406 and the second hole 711 are through-holes rather than one of them being a blind hole.

Fourthly, the first hole 406 extends from the passageway 1001 to the second end face 402 of the first gear 101B, and the second hole 711 extends from the passageway 1001 to the second end face 702 of the second gear 102B.

The method of assembling an anti-backlash gear from the assembly of Figs. 19 and 20 is illustrated by Figs. 21 to 24. Figs. 21 and 22 show cross-sectional views of the first gear 101B and second gear 102B, similar to the view of Fig. 20, and Figs. 23 and 24 show front views.

In the present method, as shown in Fig. 21, a first end 1101 of a spring member 110 is inserted through an opening 2101 of the second hole 711 in the second gear 102B and then passed through the second hole 711 and the passageway 1001 into the first hole 406 in the first gear 101B. The spring member 110 is then pushed further through the first and second gears 101B and 102B until an end portion 2103 of the spring member 110, adjacent to the first end 1101, emerges from the first hole406, as shown in Fig. 22. The end portion 2103 of the spring member 110 may then be bent to locate it against the second end face 402 of the first gear 101B as shown in Fig. 23.

One of the first gear 101B and the second gear 102B is then rotated with respect to the other one of the first gear 101B and the second gear 102B, typically through 270 degrees. During the rotation, the spring member 110 is fed through the second hole 711 and into the passageway 1001, so that a portion of the spring member 110 is wrapped around the protrusion 107 from the second hole 711 to the first hole 406.

A stopping means is then provided to prevent further movement of the spring member 110 into the opening 2101 of the second hole 711. The stopping means may comprise affixing an end portion 2401 of the spring member 110 to the second end surface 702 of the second gear 102B, but in the present embodiment the stopping means is formed by bending the end portion 2401 of the spring member 110 against the second end surface 702 of the second gear 102B to prevent the end portion 2401 from passing through the opening 2101, as shown in Fig. 24.

Fig. 24 shows the anti-backlash gear 100B assembled as described above. However, it may be noted that the anti-backlash gear 100B of Fig. 24 could have been assembled in an 18 alternative method in which the first end 1101 of the spring member 110 is pushed through the opening 2102 (shown in Fig. 21) into the first hole 406, and through the first hole 406 and the second hole 711.

Like the previously described anti-backlash gears 100 and 100A, the protrusion 107 of the second gear 102B of the anti-backlash gear 100B has a peripheral surface 108 that has a cylindrical first region 109 extending more than 180 degrees about a central axis 104 (which extends into the page in Fig. 24). The first region 109 meets a second region 705 of the peripheral surface 108 at axially extending corners 706 and 707. A first section 1301 of the spring member 110 extends from the second hole 711 in the protrusion 107 around the protrusion 107 to the first corner 706. A second section 1302 of the spring member 110 extends across the second region 705 from the first corner 706 to the second corner 707. A third section 1303 of the spring member 110 extends from the second corner 707 to the first hole 406 in the first gear 101B (as shown in Fig. 24).

By rotating the first gear 101B relative to the second gear 102B (counter-clockwise as viewed in Fig. 24), the length of the second section 1302 may be reduced. This results in the second section 1302 being flexed away from the groove 405 in the first gear 101B and towards the second region 705 of the peripheral surface 108 of the protrusion 107 of the second gear 102B. The resilience of the spring member 110 resists such flexing, and urges the first gear 101B to rotate in the opposite direction. Thus, with the spring member 110 stressed in this way, the anti-backlash gear 100B may eliminate backlash as described for anti-backlash gear 100 with regard to Fig. 15.

In a further alternative embodiment (not shown), an anti-backlash gear 100 comprises a passageway 1001 defined by the interior surface 106 of the first gear 101 and a groove 710 in the cylindrical first region 109 of the peripheral surface 108 of the protrusion 107. I.e. the interior surface 106 of the first gear 101 does not have a groove (like the groove 405 of the interior surface 106 of the first gear 101 of the anti-backlash gear 100 of Fig. 1) and the passageway 1001 is formed by only one groove, which is in the peripheral surface 108 of the protrusion 107.

Yet another anti-backlash gear 100C embodying the present invention is shown in Fig. 27. The first gear 101C and the second gear 102C of the anti-backlash gear 100C are shown assembled together in a front view in Fig. 25 and a cross-sectional side view in Fig. 26.

The first gear 101C and the second gear 102C have peripheral surfaces 403 and 703 which define teeth 103 arranged symmetrically about a central axis 104.

The first gear 101C has an interior surface 106 which defines an axial bore 105, but differs from previous embodiments in that the interior surface 106 comprises an annular step 2610 (shown in Fig. 26). The step 2610 separates a first part 2601 of the interior surface 106 from a second part 2602. The first part 2601 of the interior surface 106 has a first diameter and extends for a first distance along the central axis 104 from the first end face 402 of the first gear 101C to the step 2610. The second part 2602 of the interior surface 106 has a second diameter, larger than the first diameter, and extends for a second distance along the central axis 104 from the step 2610 to the first end face 401 of the first gear 101C.

The second gear 102C comprises a protrusion 107, which has a peripheral surface 108 that also comprises an annular step 2611. The step 2611 separates a first part 2603 of the peripheral surface 108 from a second part 2604. The first part 2603 of the peripheral surface

108 has a third diameter and extends for a third distance along the central axis 104 from the end face 708 of the protrusion 107 to the step 2611. The second part 2604 of the peripheral surface 108 has a fourth diameter and extends for a fourth distance along the central axis 104 from the step 2611 to a main body 700 of the second gear 102C. The fourth diameter of the second part 2604 is arranged to fit within the second part 2602 of the interior surface 106 of the first gear 101C.

The first part 2603 of the peripheral surface 108 of the protrusion 107 has a first region 109 that extends along a cylindrical curve with a diameter (i.e. the third diameter) arranged to fit within the first part 2601 of the interior surface 106 of the first gear 101C. The first part 2603 of the peripheral surface 108 also comprises a second region 705 that meets the first region

109 at axially extending corners 706 and 707. The whole of the second region 705 is arranged to be closer to the central axis 104 than the first region 109. In the embodiment of Figs. 25 to 27, the second region 705 is flat and parallel to the central axis 104.

The fourth distance, by which the second part 2604 of the peripheral surface 108 of the second gear 102C extends from the main body 700 to the step 2611 is shorter than the second distance by which the second part 2602 of the interior surface 106 extends from the first end face 401 of the first gear 101C to the step 2610. Consequently, a passageway 1001 is formed between the step 2610 in the first gear 101C and the step 2611 in the second gear 102C, and between the first part 2603 of the peripheral surface 108 of the protrusion 107 and the second part 2602 of the interior surface 106 of the first gear 101C.

A first hole 406 extends through the first gear 101C from the passageway 1001 to an exterior end face 402 of the first gear 101C, and a second hole 711 extends through the second gear 102C from the passageway 1001 to an exterior end face 702 of the second gear 102C.

A spring member 110 is assembled with the first gear 101C and the second gear 102C to form the anti-backlash gear 100C, shown in Fig. 27. The method of assembly may be as described above with regard to Figs. 21 to 24 for anti-backlash gear 100B.

An example of the use of an anti-backlash gear 100, 100A, 100B or 100C is illustrated in Fig. 28, which shows a vehicle 2800 embodying the present invention. The vehicle 2800 comprises a body 2801 supported on four road wheels 2802 via suspension arrangements 2803.

The suspension arrangements 2803 for the two front wheels 2802A are connected by an anti-roll bar 2804A and the suspension arrangements 2803 for the two rear wheels 2802B are connected by another anti-roll bar 2804B.

The anti-roll bars 2804A and 2804B are active anti-roll bars each comprising a left arm 2805 connected to a right arm 2806 by an actuation means 2807 for adjusting torsional forces between the left arm 2805 and the right arm 2806. The actuation means 2807 comprises an electric motor 2808 connected to an input shaft (not shown) of a reduction gear arrangement 2809 comprising a planetary gear set. The electric motor 2808 is also connected to the left arm 2805 of the respective anti-roll bar 2804A, 2804B, and an output shaft (not shown) of the reduction gear arrangement 2809 is connected to the right arm 2806. The reduction gear arrangement 2809 comprises at least one anti-backlash gear 100, 100A, 100B or 100C as described above, that has teeth engaged with teeth of another gear to eliminate backlash, as described with reference to Fig. 15.

Alternatively, or in addition, an anti-backlash gear embodying the present invention, such as anti-backlash gear 100, 100A, 100B or 100C, may be included within driveline components such as the engine 2810, the transmission 2811, etc. to eliminate backlash between gears.

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed.

Features described in the preceding description may be used in combinations other than the combinations explicitly described.

Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims (29)

1. A method of assembling an anti-backlash gear comprising:

positioning a protrusion of a second gear within an axial bore of a first gear to form a passageway that extends around the protrusion, the passageway being defined by a first surface of the first gear and a second surface of the second gear;

aligning a first hole, which extends through the first gear from the passageway, with a second hole, which extends through the second gear from the passageway;

passing a first end of a spring member through an opening of the first hole and through the first hole into the second hole, or passing a first end of a spring member through an opening of the second hole and through the second hole into the first hole; and rotating one of the first gear and the second gear with respect to the other one of the first gear and the second gear to cause a portion of the spring member to extend along the passageway from the first hole to the second hole.

2. The method according to claim 1, wherein the method comprises providing a stopping means to prevent movement of the spring member into the opening of the first hole and/or providing a stopping means to prevent movement of the spring member into the opening of the second hole.

3. The method according to claim 2, wherein providing the stopping means comprises at least one of: affixing an end portion of the spring member to an exterior surface of the first gear or the second gear; bending an end portion of the spring member to prevent the end portion from passing through the opening.

4. The method according to any one of claims 1 to 3, wherein the method comprises further rotating the first gear or the second gear to cause elastic deformation of a section of the spring member.

5. The method according to claim 4, wherein the spring member comprises a wire or a strip of resilient material, and said further rotating of the first gear or the second gear causes a decrease in a radius of curvature of the spring member around a corner of the protrusion.

6. The method according to any one of claims 1 to 5, wherein the first hole and/or the second hole extend in a direction having a radial component.

7. The method according to any one of claims 1 to 5, wherein the first hole and/or the second hole extend in a direction having an axial component.

8. The method according to any one of claims 1 to 7, wherein the first surface of the first gear comprises a groove in an interior surface defining the axial bore, and/or the second surface of the second gear comprises a groove on a peripheral surface of the protrusion.

9. The method according to any one of claims 1 to 8, wherein the method comprises temporarily locating a former against a region of the peripheral surface to support the spring member during said rotating.

10. The method according to any one of claims 1 to 9, wherein the first surface of the first gear comprises a groove in an interior surface defining the axial bore, and the second surface of the second gear comprises a groove on a peripheral surface of the protrusion, and the method comprises positioning the groove in the interior surface alongside the groove in the peripheral surface to form the passageway.

11. An anti-backlash gear comprising a first gear, a second gear and a spring member resiliently deformable by rotation of one of the first gear and the second gear with respect to the other one of the first gear and the second gear, wherein:

the first gear comprises an axial bore defined by an interior surface extending circumferentially around the axial bore;

the second gear comprises a protrusion having a peripheral surface, the protrusion being configured to rotate within the axial bore with at least a portion of the peripheral surface extending circumferentially alongside the interior surface of the first gear;

a passageway extending around the protrusion, the passageway being defined by a surface of the first gear and a surface of the second gear;

the first gear defines a first hole extending from the passageway;

the second gear defines a second hole extending from the passageway;

the spring member comprises a first portion extending along the first hole, a second portion extending along the passageway, and a third portion extending along the second hole; and the first hole extends to an exterior surface of the first gear, and/or the second hole extends to an exterior surface of the second gear.

12. An anti-backlash gear according to claim 11, wherein the first hole extends to the exterior surface of the first gear in a direction having a radial component.

13. An anti-backlash gear according to claim 12, wherein the first hole extends to an opening between two teeth of the first gear.

14. An anti-backlash gear according to claim 11, wherein the first hole extends to the exterior surface of the first gear in an axial direction or a direction having an axial component and/or the second hole extends to the exterior surface of the second gear in an axial direction or a direction having an axial component.

15. An anti-backlash gear according to any one of claims 11 to 14, wherein the second hole is a blind hole.

16. An anti-backlash gear according to any one of claims 11 to 15, wherein the second hole extends in radial direction or a direction having a radial component.

17. An anti-backlash gear according to any one of claims 11 to 16, wherein the second portion of the spring member has a cross-sectional shape and the first portion and/or the third portion have the same cross-sectional shape as the second portion.

18. An anti-backlash gear according to any one of claims 11 to 17, wherein the spring member comprises a wire or a strip formed of a resilient material.

19. An anti-backlash gear according to any one of claims 11 to 18, wherein: the protrusion has at least a first part that holds a first section of the spring member at least a first distance from a central axis of the axial bore; a region of the peripheral surface is disposed between a second section of the spring member and the central axis; all distances from the central axis to the region of the peripheral surface are less than the first distance; and the second section of the spring member is elastically deflectable towards the region by rotation of one of the first gear and the second gear with respect to the other one of the first gear and the second gear.

20. An anti-backlash gear according to claim 19, wherein the protrusion holds a third section of the spring member at least the first distance from the central axis, and the second section extends between the first section and the third section.

21. An anti-backlash gear according to claim 19 or claim 20, wherein the region is flat.

22. An anti-backlash gear according to claim 21, wherein a cross-section of the protrusion is defined by: the region of the peripheral surface; an arc of a circle; and corners between the region and the arc, which have a smaller radius of curvature than the arc.

23. An anti-backlash gear according to any one of claims 11 to 22, wherein the spring member holds the first gear and the second gear together.

24. An anti-backlash gear according to any one of claims 11 to 23, wherein the spring member is configured to resiliently bias one of the first gear and the second gear with respect to the other one of the first gear and the second gear.

25. An anti-backlash gear according to any one of claims 11 to 24, wherein the passageway is defined at least in part by a groove in the interior surface and/or a groove in the peripheral surface.

26. An anti-backlash gear according to any one of claims 11 to 25, wherein the passageway is defined at least in part by a groove in the interior surface and a groove in the peripheral surface.

27. A gear arrangement comprising the anti-backlash gear of any one of claims 11 to 26 and at least one other gear engaged with the anti-backlash gear, wherein the second section of the spring member is elastically deflected away from the interior surface towards the region to cause teeth of the first gear to be urged against one side of teeth of the at least one other gear, and teeth of the second gear to be urged against the other side of the teeth of the at least one other gear.

28. An anti-roll bar comprising an electric motor and a reduction gear arrangement, in

5 which the reduction gear arrangement includes the anti-backlash gear of any one of claims 11 to 27.

29. A vehicle comprising an anti-backlash gear according to any one of claim 11 to 26, a gear arrangement according to claim 27 and/or an anti-roll bar according to claim 28.