WO2013175178A1

WO2013175178A1 - Hub and wheel

Info

Publication number: WO2013175178A1
Application number: PCT/GB2013/051263
Authority: WO
Inventors: Samuel Blackburn Pearce
Original assignee: Jelly Products Limited
Priority date: 2012-05-22
Filing date: 2013-05-16
Publication date: 2013-11-28
Also published as: GB2502296A; GB201208995D0; TW201406566A; GB2502296B

Abstract

A hub (10) for a wheel (40) incorporating resilient spokes (36) to connect the hub (10) to a rim (38). The hub (10) comprises a hub body (12) having a through hole (14) defining an axis of rotation (A) of the hub (10) and a plurality of spoke mounts (16) for connection, in use, to resilient spokes (36) extending between the hub (10) and a rim (38). The spoke mounts (16) are pivotably mounted in pairs about an outer circumferential surface (18) of the hub body (12) at locations equidistantly spaced from, and about, the axis of rotation (A) of the hub (10). Each pair of spoke mounts (16) is mounted for pivotable movement about a common pivot axis (B) extending generally parallel to the axis of rotation (A) of the hub (10). The spoke mounts (16) in each pair are mounted about the outer circumferential surface (18) of the hub body (12) so as to be located on opposite sides of a circumferential hub line (C) from each other. The circumferential hub line (C) extends about the outer circumferential surface (18) of the hub body (12), around the axis of rotation of the hub (A) The hub (10) further includes a plurality of damping elements (20), each damping element (20) being coupled between a respective spoke mount (16) and the hub body (12) to control pivotable movement of the spoke mount (16), about the respective pivot axis (A), relative to the hub body (12).

Description

HUB AND WHEEL

The invention relates to a hub for a wheel incorporating resilient spokes to connect the hub to a rim. The invention also relates to a wheel including the hub.

Wheel-based vehicles and machinery often experience shock and/or loss of control when one or more of the wheels is subjected to an impact or is driven over an uneven driving surface. In order to overcome this problem such vehicles and machinery are often equipped with suspension systems including springs and dampers connected to each of the wheels so as to absorb impacts and to assist in the control of the wheels. The inclusion of such suspension also helps to ensure that the wheels of such vehicles and machinery remain in contact with a driving surface, regardless of the condition of the surface, and thereby helps to ensure the comfort and well-being of any occupants. Conventionally the suspension systems used are distinct apparatus connected to each of the wheels. The inclusion of one of more suspension systems therefore increases the size, weight and manufacturing costs of wheel-based vehicles and machinery.

Wheels having integrated suspension systems are disclosed in US 1 ,445,522 and EP 2 020 308.

According to an aspect of the invention there is provided a hub for a wheel incorporating resilient spokes to connect the hub to a rim, the hub comprising a hub body having a through hole defining an axis of rotation of the hub, and a plurality of spoke mounts for connection, in use, to resilient spokes extending between the hub and a rim, the spoke mounts being pivotably mounted in pairs about an outer circumferential surface of the hub body at locations equidistantly spaced from, and about, the axis of rotation of the hub, each pair of spoke mounts being mounted for pivotable movement about a common pivot axis extending generally parallel to the axis of rotation of the hub, wherein the spoke mounts in each pair are mounted about the outer circumferential surface of the hub body so as to be located on opposite sides of a circumferential hub line from each other, the circumferential hub line extending about the outer circumferential surface of the hub body, around the axis of rotation of the hub, and wherein the hub further includes a plurality of damping elements, each damping element being coupled between a respective spoke mount and the hub body to control pivotable movement of the spoke mount, about the respective pivot axis, relative to the hub body. The provision of spring mounts that are pivotably mounted in pairs about an outer circumferential surface of the hub body is advantageous in the construction of a wheel incorporating resilient spokes connected between the hub and a rim of the wheel where the use of resilient spokes allows displacement of the hub relative to the rim and thereby provides an integrated suspension system. This is because the pivotably mounted spoke mounts provide a means for connecting each spoke to the hub in a manner that allows movement of the spoke at one end relative to the hub. This in turn allows the use of a spoke that is stronger and less flexible than would otherwise be the case if the spoke were fixedly connected to the hub because it reduces the force required to produce the same deflection when compared with a rigid connection at this hub, and so results in a better lateral stiffness to compression ratio.

Effectively the provision of pivotable spoke mounts about the hub body, for connecting resilient spokes to the hub results in a structure, when used in a wheel, that is able to respond and react better to a force that results in displacement of the hub relative to the rim of the wheel.

The provision of damping elements coupled between each spoke mount and the hub body to control pivotable movement of the spoke mount, about the respective pivot axle, relative to the hub body further improves the performance of a wheel incorporating the hub. This is because, whilst the use of pivotably mounted spoke mounts allows the use of stronger spokes that achieve the desired compression and extension of the spokes when the wheel is subjected to a force causing displacement of the hub relative to the rim, the damping elements absorb the reaction force that might otherwise cause a bounce or trampoline effect. The damping elements in effect absorb or dissipate the reaction force that would otherwise cause the spoke mounts to oscillate relative to the hub body as a result of the reaction force that is created on compressing and extending the spokes It will be appreciated therefore that a hub incorporating a plurality of pivotably mounted spring mounts and a damping element coupled between each of the spring mounts and the hub body greatly improves the strength and performance of a wheel constructed using the hub in combination with a plurality of resilient spokes to connect the hub to a rim.

The relative positions of the spring mounts, that are mounted in pairs on common pivot axes so that the spring mounts in each pair are located on opposite sides of a circumferential hub line extending about the outer circumferential surface of the hub body, about the axis of rotation of the hub, allows resilient spokes, in use, to be connected to the hub in opposing pairs. In preferred embodiments, the spoke mounts are pivotably mounted about the outer circumferential surface of the hub body by means of mounting axles secured to the hub body about the outer circumferential surface thereof at locations equidistantly spaced from, and about, the axis of rotation of the hub so that each mounting axles extends generally parallel to the axis of rotation of the hub, each pair of spoke mounts being pivotably mounted on a respective mounting axle.

The use of mounting axles provides a convenient and effective means for pivotably mounting the spoke mounts in pairs for pivotable movement about a common pivot axis. So as to facilitate the connection of resilient spokes, each spring mount may include a mounting block having a through hole to receive a respective mounting axle and a mounting flange extending from the mounting block for connection, in use, to a resilient spoke, the spoke mounts of each pair of spoke mounts being mounted on the respective mounting axle in opposite orientations to each other and so that the spoke mounts mounted on each of the mounting axles, on the same side of the circumferential hub line as each other, are oriented in the same direction.

The provision of a mounting flange extending from the mounting block allows the end of a resilient spoke to be securely connected to a respective spoke mount by means of fixings extending through both the spoke and the mounting flange. This in turn results in a relatively strong but simple structure that allows adjustment of the position of the spoke relative to the mounting flange and thereby allows adjustment of the performance of the spoke. The positions of the damping elements may be varied depending on the position of the mounting flange relative to the mounting block in each spring mount.

Each damping element may, for example, be coupled between a respective mounting flange and the hub body to control pivotable movement of the mounting flange, about the respective pivot axis, relative to the hub body. In other embodiments each damping element may be coupled between a respective mounting block and the hub body to control pivotable movement of the mounting block, about the respective pivot axis, relative to the hub body. Preferably, in order to achieve the desired performance of the damping elements, each damping element is a dashpot damper.

The use of damping elements in the form of dashpot dampers results in a structure in which it is possible to most effectively control the extent to which each spoke mount moves relative to the hub body when it is subject to a force. This arrangement allows the spoke mounts to react quickly when a wheel incorporating the hub is subjected to a force causing movement of the hub relative to the rim whilst causing the spoke mounts to react slowly in response to the reaction force caused by the compression and extension of the spokes and thus smoothing out the effects of the initial force causing displacement of the hub relative to the rim.

The dashpot damper may be selected from a group comprising a rubber stopper, a mechanical dashpot damper, an electromagnetic dashpot damper, a hydraulic dashpot damper and a hydrostatic dashpot damper.

The performance of the hub is further improved in embodiments of the invention by the inclusion of a plurality of guides spaced about the outer circumferential surface of the hub body, each guide being arranged to receive and guide pivotable movement of a respective spoke mount about the respective pivot axis, relative to the hub body, and thereby prevent twisting movement of the respective spoke mount relative to the respective pivot axis.

The provision of guides to guide movement of the spoke mounts relative to the hub body reduces the manufacturing tolerances that would otherwise be required. Pivotably mounting the spoke mounts relative to the hub body greatly amplifies movement of the spoke mounts relative to the hub body and would otherwise thus require high manufacturing tolerances to ensure that none of the spoke mounts may twist relative to its respective pivot axis. The provision of a plurality of guides to guide movement of the spoke mounts, and effectively restrain the spoke mounts against moving in any other direction relative to the hub, reduces these manufacturing tolerances. It will be appreciated that the relative positions of the spoke mounts will be determined by the numbers of pairs of spoke mounts included on the hub. In embodiments including three pairs of spoke mounts, the spoke mounts are pivotably mounted about the circumferential surface of the hub body so that adjacent pairs of spoke mounts are located 120° apart.

In other embodiments, including four pairs of spoke mounts, the spoke mounts are pivotably mounted about the circumferential surface of the hub body so that adjacent pairs of spoke mounts are located 90° apart.

As outlined above, the hub is intended for inclusion in a wheel incorporating resilient spokes to connect the hub to a rim of the wheel. In such embodiments, a plurality of resilient spokes are preferably arranged to define pairs of opposed spokes spaced circumferentially around the wheel, each spoke being connected at or towards one end to the hub and at or towards its other end to the rim, the hub defining an axis of rotation of the wheel that is coincident with the axis of rotation of the hub, wherein the spokes of each pair of opposed spokes are connected to the hub via spoke mounts located on opposite sides of the circumferential hub line and are connected to the rim on a circumferential rim line that extends about an inner circumferential surface of the rim, around the axes of rotation of the wheel and the hub and concentrically aligned with the circumferential hub line, the spokes of each pair of opposed spokes being shaped to follow curved profiles extending towards each other as they extend towards the rim.

The use of resilient spokes defining curved profiles along at least part of their lengths allows displacement of the hub radially relative to the rim and thereby provides an integrated suspension system. Each of the spokes behaves as a resilient spring when, for example, the hub experiences a force that results in displacement of the hub radially relative to the rim and the spoke is either elongated or compressed under the resultant radial load. This removes the need for external suspension and therefore reduces the number of components that would otherwise be associated with the wheel, thereby resulting in size and cost benefits.

Arranging the spokes so as to define pairs of opposed spokes in which curved profiles of the spokes are oriented to oppose each other allows the spokes to apply opposing turning forces to the hub when a driving force is applied to either the hub or the rim. Consequently the arrangement of spokes acts to resist rotation of the hub relative to the rim and thereby reduces any lag between rotation of the hub and rotation of the rim when any such driving torque is applied. This is the case regardless of whether the driving torque acts to accelerate or decelerate rotation of the wheel, and regardless of the direction of the driving torque applied to the hub or the rim. Connecting the spokes of each pair of opposed spokes to the hub on opposite sides of a circumferential hub line that extends about an outer circumferential surface of the hub, and connecting each spoke to the rim on a circumferential rim line that extends about an inner circumferential surface of the rim and is concentrically aligned with the circumferential hub line has been found to be particularly advantageous. It improves the lateral stability of the wheel by resisting lateral or twisting movement of the hub relative to the rim when a lateral force is applied to the rim or the hub.

Such positioning of the connections between the spokes of each pair of opposing spokes and the hub and rim, relative to the circumferential hub and rim lines, also allows adjacent spokes to pass each other so as to assist with the positioning of the spokes within the normal envelope of a rim and hub, particularly in the event the spokes are compressed during movement of the hub relative to the rim causing adjacent pairs of opposing spokes to move towards each other. There is a risk otherwise that the adjacent spokes might collide.

The circumferential hub line may be centrally located relative to the width of the outer circumferential surface of the hub. Similarly the circumferential rim line may be centrally located relative to the width of the inner circumferential surface of the rim. It will however be appreciated that such central positioning of the circumferential hub and rim lines is not necessary, provided that the circumferential rim line is concentrically aligned with the circumferential hub line.

In embodiments of the invention, the spokes of each pair of opposed spokes may be connected to the hub via spoke mounts located on opposite sides of the circumferential hub line and mounted for pivotable movement about the same pivot axis, the spokes of each pair of opposed spokes being shaped to extend away from each other as they extend away from the hub and thereafter follow curved profiles extending back towards each other as they extend towards the rim. In other embodiments of the invention, the spokes of each pair of opposed spokes may be connected to the hub via spoke mounts located on opposite sides of the circumferential hub line and mounted for pivotable movement about adjacent pivot axes, the spokes of each pair of opposed spokes being shaped to pass each other as they extend away from the hub and thereafter follow curved profiles extending back towards each other as they extend towards the rim. Connecting the spokes of each pair of opposed spokes to the hub in this manner results in connections at circumferentially spaced locations along the length of the circumferential hub line. This spacing increases the lateral stability of the wheel, preventing twisting movement of the hub relative to the rim, and also increases the ability of the spokes to resist turning of the hub relative to the rim, particularly when accelerating or decelerating. It will be appreciated however that the provision of spoke mounts mounted in pairs allows resilient spokes to be connected to the hub in a number of different configurations and arrangements, depending on the intended use of the wheel and the desired performance of the spokes. According to a second aspect of the invention there is provided a wheel comprising a hub, a rim and a plurality of resilient spokes arranged to define pairs of opposed spokes spaced circumferentially about the wheel, each spoke being connected at or towards one end to the hub and at or towards its other end to the rim, the hub including a hub body having a through hole defining coincident axes of rotation of the wheel and hub and a plurality of spoke mounts pivotably mounted in pairs about an outer circumferential surface of the body at locations equidistantly spaced from, and about, the axes of rotation of the wheel and hub, each pair of spoke mounts being mounted for pivotable movement about a common pivot axis extending generally parallel to the axes of rotation of the wheel and hub, wherein the spoke mounts in each pair are mounted about the outer circumferential surface of the hub body so as to be located on opposite sides of a circumferential hub line that extends about the outer circumferential surface of the hub body, around the axes of rotation of the wheel and hub, and wherein the spokes of each pair of opposed spokes are connected to the hub via spoke mounts located on opposite sides of the circumferential hub line and mounted for pivotable movement about adjacent pivot axes, and are connected to the rim on a circumferential rim line that extends about an inner circumferential surface of the rim, around the axes of rotation of the wheel and hub and concentrically aligned with the circumferential hub line, the spokes of each pair of opposed spokes being shaped to pass each other as they extend away from the hub and thereafter follow curved profiles extending back towards each other as they extend towards the rim. As outlined above, the use of resilient spokes defining curved profiles along at least part of their lengths allows displacement of the hub radially relative to the rim and thereby provides an integrated suspension system. Each of the spokes behaves as a resilient spring when, for example, the hub experiences a force that results in displacement of the hub radially relative to the rim and the spoke is either elongated or compressed under the resultant radial load. This removes the need for external suspension and therefore reduces the number of components that would otherwise be associated with the wheel, thereby resulting in size and cost benefits. Arranging the spokes so as to define pairs of opposed spokes in which curved profiles of the spokes are oriented to oppose each other allows the spokes to apply opposing turning forces to the hub when a driving force is applied to either the hub or the rim. Consequently the arrangement of spokes acts to resist rotation of the hub relative to the rim and thereby reduces any lag between rotation of the hub and rotation of the rim when any such driving torque is applied. This is the case regardless of whether the driving torque acts to accelerate or decelerate rotation of the wheel, and regardless of the direction of the driving torque applied to the hub or the rim.

Connecting the spokes of each pair of opposed spokes to the hub on opposite sides of a circumferential hub line that extends about an outer circumferential surface of the hub, and connecting each spoke to the rim on a circumferential rim line that extends about an inner circumferential surface of the rim and is concentrically aligned with the circumferential hub line has been found to be particularly advantageous. It improves the lateral stability of the wheel by resisting lateral or twisting movement of the hub relative to the rim when a lateral force is applied to the rim or the hub.

Such positioning of the connections between the spokes of each pair of opposing spokes and the hub and rim, relative to the circumferential hub and rim lines, also allows adjacent spokes to pass each other so as to assist with the positioning of the spokes within the normal envelope of a rim and hub, particularly in the event the spokes are compressed during movement of the hub relative to the rim causing adjacent pairs of opposing spokes to move towards each other. There is a risk otherwise that the adjacent spokes might collide. Connecting the spokes of each pair of opposed spokes to the hub via spoke mounts mounted for pivotable movement on adjacent pivot axes, so that the spokes extend towards and pass each other as they extend away from the hub results in greatly increases the lateral stability of the wheel, preventing twisting movement of the hub relative to the rim. The circumferential spacing between the hub connections also increases the ability of the spokes to resist turning of the hub relative to the rim, particularly when accelerating or decelerating.

It will be appreciated that the circumferential hub line may be centrally located relative to the width of the outer circumferential surface of the hub. Similarly the circumferential rim line may be centrally located relative to the width of the inner circumferential surface of the rim. It will also however be appreciated that such central positioning of the circumferential hub and rim lines is not necessary, provided that the circumferential rim line is concentrically aligned with the circumferential hub line.

Connecting the spokes to the hub via spring mounts that are pivotably mounted in pairs about an outer circumferential surface of the hub body is advantageous it provides a means for connecting each spoke to the hub in a manner that allows movement of the spoke at one end relative to the hub. This in turn allows the use of spokes that are stronger and less flexible than would otherwise be the case if the spokes were fixedly connected to the hub because it reduces the force required to produce the same deflection when compared with a rigid connection at this hub, and so results in a better lateral stiffness to compression ratio.

Effectively the use of pivotable spoke mounts about the hub body to connect resilient spokes to the hub results in a structure that is able to respond and react better to a force that results in displacement of the hub relative to the rim of the wheel.

In preferred embodiments, the spoke mounts are pivotably mounted about the outer circumferential surface of the hub body by means of mounting axles secured to the hub body about the outer circumferential surface thereof at locations equidistantly spaced from, and about, the axis of rotation of the hub so that each mounting axles extends generally parallel to the axis of rotation of the hub, each pair of spoke mounts being pivotably mounted on a respective mounting axle.

The use of mounting axles provides a convenient and effective means for pivotably mounting the spoke mounts in pairs for pivotable movement about a common pivot axis.

So as to facilitate the connection of resilient spokes, each spring mount may include a mounting block having a through hole to receive a respective mounting axle and a mounting flange extending from the mounting block for connection, in use, to a resilient spoke, the spoke mounts of each pair of spoke mounts being mounted on the respective mounting axle in opposite orientations to each other and so that the spoke mounts mounted on each of the mounting axles, on the same side of the circumferential hub line as each other, are oriented in the same direction.

The provision of a mounting flange extending from the mounting block allows the end of a resilient spoke to be securely connected to a respective spoke mount by means of fixings extending through both the spoke and the mounting flange. This in turn results in a relatively strong but simple structure that allows adjustment of the position of the spoke relative to the mounting flange and thereby allows adjustment of the performance of the spoke.

The performance of the wheel may be further improved by the inclusion of a plurality of damping elements, each damping element being coupled between a respective spoke mount and the hub body to control pivotable movement of the spoke mount, about the respective pivot axis, relative to the hub body.

The provision of damping elements coupled between each spoke mount and the hub body to control pivotable movement of the spoke mount, about the respective pivot axle, relative to the hub body further improves the performance of the wheel. This is because, whilst the use of pivotably mounted spoke mounts allows the use of stronger spokes that achieve the desired compression and extension of the spokes when the wheel is subjected to a force causing displacement of the hub relative to the rim, the damping elements absorb the reaction force that might otherwise cause a bounce or trampoline effect. The damping elements in effect absorb or dissipate the reaction force that would otherwise cause the spoke mounts to oscillate relative to the hub body as a result of the reaction force that is created on compressing and extending the spokes It will be appreciated therefore that the use of a plurality of pivotably mounted spring mounts and a damping element coupled between each of the spring mounts and the hub body greatly improves the strength and performance of the wheel.

The positions of the damping elements may be varied in embodiments where each spoke mount includes a mounting block and a mounting flange depending on the position of the mounting flange relative to the mounting block in each spring mount. Each damping element may, for example, be coupled between a respective mounting flange and the hub body to control pivotable movement of the mounting flange, about the respective pivot axis, relative to the hub body. In other embodiments each damping element may be coupled between a respective mounting block and the hub body to control pivotable movement of the mounting block, about the respective pivot axis, relative to the hub body.

Preferably, in order to achieve the desired performance of the damping elements, each damping element is a dashpot damper.

The use of damping elements in the form of dashpot dampers results in a structure in which it is possible to most effectively control the extent to which each spoke mount moves relative to the hub body when it is subject to a force. This arrangement allows the spoke mounts to react quickly when the wheel is subjected to a force causing movement of the hub relative to the rim whilst causing the spoke mounts to react slowly in response to the reaction force caused by the compression and extension of the spokes and thus smoothing out the effects of the initial force causing displacement of the hub relative to the rim.

The dashpot damper may be selected from a group comprising a rubber stopper, a mechanical dashpot damper, an electromagnetic dashpot damper, a hydraulic dashpot damper and a hydrostatic dashpot damper. The performance of the hub is further improved in embodiments of the invention by the inclusion of a plurality of guides spaced about the outer circumferential surface of the hub body, each guide being arranged to receive and guide pivotable movement of a respective spoke mount about the respective pivot axis, relative to the hub body, and thereby prevent twisting movement of the respective spoke mount relative to the respective pivot axis.

The provision of guides to guide movement of the spoke mounts relative to the hub body reduces the manufacturing tolerances that would otherwise be required. Pivotably mounting the spoke mounts relative to the hub body greatly amplifies movement of the spoke mounts relative to the hub body and would otherwise thus require high manufacturing tolerances to ensure that none of the spoke mounts may twist relative to its respective pivot axis. The provision of a plurality of guides to guide movement of the spoke mounts, and effectively restrain the spoke mounts against moving in any other direction relative to the hub, reduces these manufacturing tolerances.

It will be appreciated that the relative positions of the spoke mounts will be determined by the numbers of pairs of spoke mounts included on the hub. In embodiments including three pairs of spoke mounts, the spoke mounts are pivotably mounted about the circumferential surface of the hub body so that adjacent pairs of spoke mounts are located 120° apart. In other embodiments, including four pairs of spoke mounts, the spoke mounts are pivotably mounted about the circumferential surface of the hub body so that adjacent pairs of spoke mounts are located 90° apart.

In particularly preferred embodiments of a wheel according to the invention, the spokes of each pair of opposed spokes are connected to the rim in an end to end arrangement. In such embodiments, the spokes of each pair of opposed spokes may be formed integrally with one another.

In order to achieve the desired performance of the resilient spokes, and ensure that adjacent spokes do not collide when the hub moves relative to the rim so as to cause compression of the spokes, the profile of each spoke is preferably twisted and connected to the hub and the rim so that the spoke, at or towards the one end, lies in contact with a respective spoke mount along a line that is generally parallel to the axes of rotation of the wheel and the hub, and the spoke at or towards the other end lies in contact with the inner circumferential surface of the rim along a line that is generally parallel to the axes of rotation of the wheel and the hub, and the spoke extends from the respective spoke mount at an angle to the circumferential hub line.

In such embodiments the profile of each spoke may be twisted and connected to the hub and the rim so that the spoke extends from the rim at an angle to the circumferential rim line.

In other such embodiments the profile of each spoke may be twisted and connected to the hub and the rim so that the spoke extends from the rim along the circumferential rim line. Preferred embodiments of the invention will now be described, by way of non-limiting examples, with reference to the accompanying drawings in which:

Figures 1 to 3 show a hub according to an embodiment of the invention;

Figure 4 shows a schematic view of a spoke mount of the hub shown in

Figures 1 to 3;

Figures 5 and 6 show schematic views of spoke mounts of hubs according to other embodiments of the invention;

Figures 7 to 10 show a wheel according to an embodiment of the invention; Figures 1 1 a and 11 b are side and cross-sectional views of the connections between a pair of opposed spokes and a hub and rim of the wheel shown in Figures 7 to 10;

Figure 12 is a plan view from above of the wheel shown in Figures 7 to 10;

Figure 13 is a plan view from above of a wheel according to another embodiment of the invention;

Figure 14 is a schematic illustration of the resultant springs defined by two pairs of opposed spokes of the wheel shown in Figures 7 to 10;

Figure 15 is a schematic illustration of the resultant springs defined by two pairs of opposed spokes of a wheel not forming part of the invention;

Figure 16 illustrates the angular positions of adjacent mounting axles of the wheel shown in Figures 7 to 10; and

Figures 17 to 19 illustrate possible positions of mounting axles of the wheel shown in Figures 7 to 10. A hub 10 according to an embodiment of the invention is shown in Figures 1 to 3.

The hub 10 includes a hub body 12 having a through-hole 14 defining an axis of rotation A of the hub 10. The hub 10 also includes a plurality of spoke mounts 16 for connection, in use, to resilient spokes extending between the hub 10 and a rim of a wheel.

The spoke mounts 16 are pivotably mounted in pairs about an outer circumferential surface 18 of the hub body 12 so that each pair of spoke mounts 16a, 16b is mounted for pivotable movement about a common pivot axis B extending generally parallel to the axis of rotation A of the hub 10. The pivot axes B are equidistantly spaced from each other about the outer circumferential surface 18 9Figure 3) of the hub body 12. The pivot axes B are also equidistantly spaced from the axis of rotation B of the hub 10. The spoke mounts 16 in each pair of spoke mounts 16a, 16b are mounted about the outer circumferential surface 18 of the hub body 12 so as to be located on opposite sides of a circumferential hub line C from each other (Figure 3). The circumferential hub line C extends about the outer circumferential surface 18 of the hub body 12, around the axis of rotation A of the hub 10.

In the embodiment shown in Figures 1 to 3, the hub 10 also includes a plurality of damping elements 20, each damping element 20 being coupled between a respective spoke mount 16 and the hub body 12 to control pivotable movement of the spoke mount 16, about the respective pivot axis B, relative to the hub body 12.

It is envisaged that in other embodiments the damping elements 20 may be omitted depending on the intended use of the hub 10 and the resilient nature of the spokes connected to the spoke mounts 16. Referring to Figure 3, it can be seen that the common pivot axes B of the pairs of spoke mounts 16a, 16b are formed by means of mounting axles 22 secured to the hub body 12 about the outer circumferential surface 18 thereof at locations equidistantly spaced from, and about, the axis of rotation A of the hub 10, each pair of spoke mounts 16a, 16b being pivotably mounted on a respective mounting axle 22.

It is envisaged that in other embodiments the common pivot axis B of each pair of spoke mounts 16a, 16b may be defined by two separate pivot pins mounted side by side on pivot pin mounts extending from the outer circumferential surface 18 of the hub body 12. In the embodiment shown in Figures 1 to 3, each spoke mount 16 includes a mounting block 24 having a through-hole 26 to receive a respective mounting axle 22 and a mounting flange 28 extending from the mounting block 24 for connection, in use, to a resilient spoke. Referring to Figure 1 it can be seen that the spoke mounts 16 of each pair of spoke mounts 16a, 16b are mounted on the respective mounting axle 22 in opposite orientations towards each other so that the mounting flanges 28 extend away from the mounting axle 22 in opposite directions to each other. It can also be seen that the spoke mounts 16 mounted on each of the mounting axles 22, on the same side of the circumferential hub line C as each other, are oriented in the same direction.

The location of the through-hole 26 in the mounting block 24 of each of the spoke mounts 16 is shown schematically in Figure 4. The through-hole 26 is located towards a lower edge of the mounting block 24, spaced from the mounting flange 28 that extends from an upper edge of the mounting block 24.

The resultant directions of pivotal movement of the mounting block 24 and the mounting flange 28 are illustrated in Figure 4 by means of arrows D and E. As a result, the damping element 20 is coupled between the mounting flange 28 and the circumferential surface 18 of the hub body 12 to control pivotable movement of the spoke mount 16 about the pivot axis B defined by the mounting axle 22. In other embodiments the location of the damping element 20 relative to the spoke mount 16 may be altered depending on the direction of pivotable movement of the spoke mount 16 relative to the hub body 12. One such embodiment is shown schematically in Figure 5 wherein the through-hole 26 is located towards an upper edge of the mounting block 24. In this embodiment the damping element 20 is coupled between the mounting block 24 and a stopper 30 provided on the outer circumferential surface 18 of the hub body 12.

In further embodiments the structure of the spoke mount 16 may be altered, such as is shown schematically in Figure 6. In the embodiment shown in Figure 6 the mounting block 24 is omitted and the through-hole 26 extends centrally through the mounting flange 28. As a result of the resultant pivotable movement of the mounting flange 28 about the mounting axle 22, the damping element 20 is coupled between an end of the mounting flange 28 and the hub body 12. It will be appreciated that the damping element could, in an alternative embodiment, be coupled between the other end of the mounting flange 28 and the hub body 12.

In the embodiments shown in Figures 1 to 6 the damping element 20 is provided in the form of a waisted stopper. The waisted stopper is preferably formed from a rubber material and is most preferably formed from Sorbothane (RTM). The use of a waisted stopped formed from Sorbothane (RTM) results in the creation of a dashpot damper coupled between each spoke mount 16 and the hub body 12. This is because the nature of the Sorbothane (RTM) means that the damping element 20 will compress when it is subjected to a relatively gradual force whereas it will not compress when it is subjected to a relatively quick and sudden force.

In other embodiments of the invention the waisted stoppers may be replaced by another dashpot damper chosen from a group including a mechanical dashpot damper, an electromagnetic dashpot damper, a hydraulic dashpot damper and a hydrostatic dashpot damper.

The use of a dashpot damper as a damping element is advantageous in that, in use in a wheel, it allows the spoke mounts 16 to react quickly when the wheel is subjected to a force causing movement of the hub relative to the rim whilst causing the spoke mounts 16 to react slowly in response to the reaction force caused by the compression and extension of the spokes and thus smoothing out the effects of the initial force causing displacement of the hub relative to the rim.

Referring to Figures 1 to 3 the hub 10 further includes a plurality of guides 32 spaced about the outer circumferential surface 18 of the hub body 12. Each guide 32 is shaped and arranged to receive and guide pivotable movement of a respective spoke mount 16 about the respective pivot axis B, relative to the hub body 12.

The guide 32 shown in Figures 1 to 3 includes an H-shaped element mounted relative to the outer circumferential surface 18 of the hub body 12 in a position where it receives a free end of the mounting flange 28 of a respective spoke mount 16 between a pair of its upstanding limbs 34 (Figure 1). Whilst the free end of the mounting flange is received between the upstanding limbs 34 of the guide 32, the mounting flange 28 is prevented from moving sideways along the mounting axle 22 and is also prevented from exhibiting any twisting movement about the mounting axle 22. The provision of the guide 32 thereby reduces the manufacturing tolerances required by the engagement between the mounting block 24 and the mounting axle 22.

In use the hub 10 a plurality of resilient spokes 36 are connected to the spoke mounts 16 so as to extend between the hub 10 and a rim 38 to form a wheel 40, as shown in Figure 7. The spokes 36 are arranged to define pairs of opposed spokes 36a, 36b spaced circumferentially around the wheel 40. Each spoke 36 is connected at or towards one end to the hub 10 and at or towards it other end to the rim 38 and the hub 10 defines an axis of rotation A of the wheel that is coincident with the axis of rotation A of the hub 10.

The spokes 36 of each pair of opposed spokes 36a, 36b are connected to the hub 10 via spoke mounts 16a, 16b located on opposite sides of the circumferential hub line C, as shown in Figures 8 to 10. The spokes 36 of each pair of opposed spokes 36a,36b are connected to the rim on a circumferential rim line F (Figure 10) that extends about an inner circumferential surface 42 of the rim 38, around the axes of rotation A of the wheel and the hub and concentrically aligned with the circumferential hub line C.

Whilst the circumferential hub line C and circumferential rim line F may be centrally located relative to the respective widths of the outer circumferential surface 18 of the hub body 12 and the inner circumferential surface 42 of the rim 38, such central positioning of the circumferential hub and rim lines C,F is not necessary. It may for example, in arrangements where a brake disk and/or gear elements are additionally mounted on one or both sides of the hub body 12 prove impossible for the circumferential hub line C to be located centrally of the outer circumferential surface 18 of the hub body 12 and there remain room to mount the resilient spokes 36. In such circumstances the circumferential hub line C may be located closer towards one or other of the two ends of the hub body 12. In such arrangements however the circumferential rim line F remains concentrically aligned with the circumferential hub line C.

Referring to Figure 7 to 10 it can be seen that the spokes 36 of each pair of opposed spokes 36a, 36b are shaped to follow curved profiles extending towards each other as they extend towards the rim 38.

More specifically, the spokes 36 of each pair of opposed spokes 36a, 36b are connected to the hub 10 via spoke mounts 16a, 16b located on opposite sides of the circumferential hub line C and mounted for pivotable movement about the pivot axes B defined by adjacent mounting axles 22. The mounting axles 22 are chosen so that the spokes 36 of each pair of opposed spokes 36a, 36b are then shaped to pass each other as they extend away from the hub 10 and thereafter follow curved profiles extending back towards each other as they extend towards the rim 38 when the opposed spokes 36a, 36b meet in an end to end arrangement on the circumferential rim line F.

It is envisaged that in other embodiments the spokes 36 of each pair of opposed spokes 36a, 36b may be connected to the hub 10 via spoke mounts 16a, 16b located on opposite sides of the circumferential hub line C and mounted for pivotable movement about the pivot axis defined by the same mounting axle 22. In such an arrangement, the spokes 36 of each pair of opposed spokes 36a,36b are then shaped to extend away from each other as they extend away from the hub 10 and thereafter follow curved profiles extending back towards each other as they extend towards the rim 38.

It is also envisaged that in other embodiments the opposed spokes 36a, 36b may not meet in an end to end arrangement on the circumferential rim line F. In the embodiment shown in Figures 7 to 10, the opposed spokes 36a, 36b are formed integrally with each other. This arrangement strengthens the wheel 40 and facilitates construction of the wheel 40 using connection portions 44 that are mounted on the inner circumferential surface 42 of the rim 38. In other embodiments it is envisaged that the opposed spokes 36a,36b may be provided in the form of two separate spokes 36.

The spokes 36 are formed from laminated structures including a plurality of alternating layers of carbon fibre and epoxy resin. The layers of carbon fibre are arranged within the laminated structures so as to be aligned along the lengths of the spokes 36 and provide a uni-directional strengthening effect.

Each spoke 36 is shaped to define a constant width W between the hub 10 and the rim 38.

In other embodiments each spoke 36 may be shaped so as to vary in width W between the hub 10 and the rim 38. In one such other embodiment, each spoke 36 may be shaped so as to reduce in width W as it extends from the hub 10 towards the rim 38 such that the width W of the spoke 36 is least at the connection between the spoke 36 and the rim 38.

As will be appreciated from Figure 7, the resilient spokes 36 of each pair of opposed spokes 36a, 36b are equal in length and define the same curved profile. This means that the hub 10 is centrally located relative to the rim 38 in an unloaded state.

The resilient nature of the spokes 36 allows the curved profile of each spoke 36 to deform on the application of a compressive or tensile load, the curvature of the curved profile of each spoke 36 increasing on the application of a compressive load and the curvature of the curved profile of the spoke 36 decreasing on the application of a tensile load. Consequently, on the application of a radial load to the hub 10, the spokes 36 deform as the hub 10 moves relative to the rim 38 in the direction of the radial load, the nature of the deformation of each spoke 36, i.e. elongation or compression, being determined by the direction of the applied load.

On removal of the radial load, the resilient nature of the spokes 16 means that each of the spokes 36 resumes its original shape and the hub 10 is thereby returned to its unloaded or rest position, centrally located within the rim 38.

Similarly, on the application of a radial load to the rim 38 so as to cause movement of the rim 38 towards the hub 10, the spokes 36 will deform in accordance with the direction of the radial load, as the rim 38 moves towards the hub 10, and will return the rim 38 to its unloaded or rest position relative to the hub 10 on removal of the load.

The arrangement of the spokes in each pair of opposed spokes 36a, 36b relative to the circumferential hub and rim lines C,F improves the lateral stability of the wheel 40 by resisting twisting movement of the hub 10 relative to the rim 38 whilst at the same time facilitating the use of a relatively narrow rim 38. This is particularly advantageous when the size of the rim 38 is an important factor in terms of the performance of the wheel 40. The use of a relatively narrow rim 38 is important, for example, in racing bicycle wheels.

Crossing of the spokes 36 in each pair of opposed spokes 36a, 36b, as they extend away from the hub 10, also increases the lateral stiffness of the wheel 40.

The width W of the spokes 36 also helps to improve the lateral stability of the wheel 40 by increasing the lateral stiffness of the spokes and thereby increases the ability of the spokes 36 to resist twisting of the hub 10 relative to the rim 38.

Arranging the spokes so as to define pairs of opposed spokes 36a,36b in which the curved profiles of the spokes 36a, 36b oppose each other, and connecting the opposed spokes 36a, 36b of each pair to the hub 10 to adjacent mounting axles 22, enables the spokes 36 to apply opposing turning forces to the hub 10 when a driving torque is applied to either the hub 10 or the rim 38. Consequently the spokes 36 act on the hub 10 to resist rotation of the hub 10 relative to the rim 38. This is particularly advantageous in circumstances where the driving torque is applied to the hub 10 to either accelerate or decelerate rotation of the wheel 40.

The extent to which the spokes 36 on their own provide an integrated suspension capability is determined by the elastic nature of the reinforcing material used in the laminated structure of each spoke 36.

The use of carbon fibre produces a relatively elastic response but is less flexible and exhibits a relatively low elastic limit. As such, whilst spokes 36 formed using carbon fibre react relatively quickly to the application of a radial load to the hub 10 or rim 38, they provide limited damping capability and are perhaps less suitable for use on their own over bumpy terrain. This is because the spokes 36 are more likely to reach their elastic limit on the application of a relatively large radial load to either the hub 10 or rim 38. This would lead to breakage of the spokes 36.

The use of pivotably mounted spoke mounts 16 to connect the spokes 36 to the hub body 12 reduces the amount of flex required by the spokes 36. This is because the spoke mounts 16 allow movement of each of the spokes 36 at one end relative to the hub 10. This in turn allows the use of a spoke 36 that is stronger and less flexible than would otherwise be the case if the spoke 36 were fixedly connected to the hub 10 because it reduces the force required to produce the same deflection when compared with a rigid connection at the hub 10, and so results in a better lateral stiffness to compression ratio. The use of pivotably mounted spoke mounts 16 thus results in a wheel 40 that is able to respond and react better to a force that results in displacement of the hub 12 relative to the rim 38 of the wheel 40.

In addition, the damping elements 20 coupled between the mounting flanges 28 and the hub body 12 in the embodiment shown in Figures 7 to 10 absorb the reaction force that would otherwise cause a bounce or trampoline effect when the wheel 40 is subjected to a force causing displacement of the hub 10 relative to the rim 38.

The damping capability of the spokes 36 themselves may be increased through the use of a reinforcing material that exhibits less of an elastic response but is more flexible, such as glass fibre. The use of glass fibre leads to the production of spokes 36 that react more slowly to radial forces applied to the hub 10 or rim 38 and thereby provides a greater damping effect. The use of glass fibre may thus be considered more suitable for use in a wheel 40 according to other embodiments of the invention where the damping elements are omitted and the wheel 40 is intended to be used over bumpy terrain. This is because the spokes 36 are less likely to reach their elastic limit on the application of a relatively large radial load to either the hub 10 or rim 38 and therefore less likely to snap.

In yet further embodiments, depending on the elastic response required from the spokes 36, Kevlar (RTM) or hemp may be used in the laminated structure used to form the spokes 36.

The spokes 16 are fixedly connected to the rim 38 so as to minimise flexing of the spokes 36 relative to the rim 38 and ensure that the spokes 36 are able to consistently apply the turning forces required to resist rotation of the hub 10 relative to the rim 38 on the application of a driving torque to the hub 10 or rim 38.

The strength of each spoke 36 at the connection between the spoke 36 and the rim 38 may be increased to cope with the stresses applied to the spokes 36 at the connections with the rim 38 through the use of one or more additional layers of carbon fibre in the laminated structure at the ends of the spokes 36 fixedly connected to the rim 38.

Referring to Figures 11a and 11 b, it can be seen that the profile of each spoke 36 of the is twisted and connected to the hub 10 and the rim 38 so that the spoke 36, at the end that is connected to the hub 10 lies in contact with the respective spoke mount 16 along a line G that is generally parallel to the axis of rotation A of the wheel 40 and the hub 10.

At its other end the spoke 36 lies in contact with the inner circumferential surface 42 of the rim 38 along a line H that is generally parallel to the axes of rotation A of the wheel 40 and the hub 10. In this twisted arrangement, each spoke 36 extends from the respective spoke mount 16 at an angle to the circumferential hub line C.

In the embodiment shown in Figures 7 to 10, the profile of each spoke 36 is twisted and connected to the hub 10 and the rim 38 so that the spoke 36 extends from the rim 38 along the circumferential rim line F, as shown in Figure 12. In other embodiments the profile of each spoke 36 may be twisted and connected to the hub 10 and the rim 38 so that the spoke 36 extends from the rim 38 at an angle to the circumferential rim line D, as shown in Figure 13. This arrangement increases the clearance between neighbouring pairs of opposed spokes 36a, 36b and allows a greater number of spokes 36 to be used in the wheel 40, which inevitably requires neighbouring pairs of opposed spokes 36a,36b to be located closer together.

The twisted profile of each spoke 36, whether or not each spoke 36 extends from the rim 38 at an angle to the circumferential rim line F, ensures that each pair of opposed spokes 36a, 36b are free to expand and compress without interfering with neighbouring pairs of opposed spokes 36a, 36b.

This is because the twisted profiles of the resultant springs defined by the pairs of opposed spokes 36a, 36b have spring axes I that are offset relative to the axes of rotation of the wheel 40 and the hub 10 (Figure 14). This allows the pairs of opposed spokes 36a, 36b to pass each other during compression without colliding with each other.

In contrast, in arrangements where the ends of the spokes 36 of a pair of opposed spokes 36a, 36b are simply connected to the hub 10 on opposite sides of the circumferential hub line C and meet at the rim 38 on the circumferential rim line F, with no twist, the ends of the opposed spokes 36a,36b must be connected to the hub 10 at a canted angle relative to the outer circumferential surface 18 of the hub body 12. This means that the resultant springs defined by the pairs of opposed spokes 36a, 36b have spring axes J that are generally parallel to the axes of rotation A of the wheel 40 and the hub 10 (Figure 15). This means that, unless the pairs of opposed spokes 36a, 36b are spaced sufficiently far apart, they will collide with each other under compression.

In the embodiment shown in Figures 7 to 10 the wheel 40 includes three pairs of opposed spokes 36a, 36b. This structure requires three pairs of spoke mounts 16 located and equidistantly spaced about the outer circumferential surface 18 of the hub body 12. As will be appreciated, the adjacent pairs of spoke mounts 16 in this embodiment are located 120° apart, as illustrated in Figure 16.

In other embodiments the number of pairs of opposed spokes 36a,36b may be increased, which will inevitably reduce the angular separation between adjacent pairs of spoke mounts 16 about the hub body 12. In an embodiment in which the wheel 40 includes four pairs of opposed spokes 36a, 36b, for example, the spoke mounts 16 required to connect the pairs of opposed spokes 36a, 36b to the hub 10 will be located 90° apart.

So as to ensure that spokes 36 of equal length retain the hub 10 in a central position relative to the rim 38 in an unloaded position, and the spokes 36 react equally when a force is subjected to the hub 10 or the rim 38 so as to cause movement of the hub 10 relative to the rim 38, the pairs of spoke mounts 16 are located at equal distances from the axes of rotation A of the wheel 40 and the hub 10. As will be appreciated, the greater the radial distance between the pairs of spoke mounts 16 and the axes of rotation of the wheel 40 and the hub 10, the greater the distance between adjacent pairs of spoke mounts 16.

Figure 16 illustrates two radial positions for the pairs of spoke mounts (1) and (2). In position (1) the distance between adjacent pairs of spoke mounts is identified as "a". In position (2) the distance between adjacent pairs of spoke mounts is identified as "b".

Since the radial distance from the axes of rotation A of the wheel 40 and hub 10 is greater in position (2), distance "b" is greater than distance "a". This increase in distance between the pairs of spoke mounts 16 increases the cross-over between the spokes 36 of each pair of opposed spokes 36a, 36b when the spokes 36 are connected to spoke mounts 36a, 36b mounted for pivotable movement on adjacent mounting axles 22. It therefore improves the torque characteristics of the wheel 40, improving the ability of the spokes 36 to resist turning movement of the hub 10 relative to the rim 38 when a driving or braking force is applied to either the hub 10 or the rim 38.

Three different radial positions of the spoke mounts 16 from the axes of rotation A of the wheel 40 and hub 10 are illustrated in Figures 17 to 19. The arrangement shown in Figure 17 illustrates the minimal position that is required in order to ensure that the spokes 36 of each opposed pair of spokes 36a, 236b do not collide with the hub 10 and can pivot freely when subject to a compressive force.

The arrangement shown in Figure 18 illustrates a mid-point position where the spoke mounts 16 are located mid-way between the hub 10 and the rim 38. In this position the spokes 36 will produce a better torque effect over the arrangement shown in Figure 17 due to the increased cross-over between the spokes 36 or each pair of opposed spokes 36a,36b as they extend away from the hub 10. This arrangement may however require a larger and/or heavier hub 10 to resist the torques produced at the hub 10.

The arrangement shown in Figure 19 illustrates the maximum position that might be utilised to maximise the torque effect. Again however, whilst the torque effect is greatly increased over the arrangements shown in Figures 17 and 18, a larger and/or heavier hub 10 is required to resist the torques produced at the hub 10.

Claims

1. A hub for a wheel incorporating resilient spokes to connect the hub to a rim, the hub comprising a hub body having a through hole defining an axis of rotation of the hub, and a plurality of spoke mounts for connection, in use, to resilient spokes extending between the hub and a rim, the spoke mounts being pivotably mounted in pairs about an outer circumferential surface of the hub body at locations equidistantly spaced from, and about, the axis of rotation of the hub, each pair of spoke mounts being mounted for pivotable movement about a common pivot axis extending generally parallel to the axis of rotation of the hub, wherein the spoke mounts in each pair are mounted about the outer circumferential surface of the hub body so as to be located on opposite sides of a circumferential hub line from each other, the circumferential hub line extending about the outer circumferential surface of the hub body, around the axis of rotation of the hub, and wherein the hub further includes a plurality of damping elements, each damping element being coupled between a respective spoke mount and the hub body to control pivotable movement of the spoke mount, about the respective pivot axis, relative to the hub body.

2. A hub according to Claim 1 wherein the spoke mounts are pivotably mounted about the outer circumferential surface of the hub body by means of mounting axles secured to the hub body about the outer circumferential surface thereof at locations equidistantly spaced from, and about, the axis of rotation of the hub so that each mounting axle extends generally parallel to the axis of rotation of the hub, each pair of spoke mounts being pivotably mounted on a respective mounting axle.

3. A hub according to Claim 2 wherein each spoke mount includes a mounting block having a through hole to receive a respective mounting axle and a mounting flange extending from the mounting block for connection, in use, to a resilient spoke, the spoke mounts of each pair of spoke mounts being mounted on the respective mounting axle in opposite orientations to each other and so that the spoke mounts mounted on each of the mounting axles, on the same side of the circumferential hub line as each other, are oriented in the same direction.

4. A hub according to Claim 3 wherein each damping element is coupled between a respective mounting flange and the hub body to control pivotable movement of the mounting flange, about the respective pivot axis, relative to the hub body.

5. A hub according to Claim 3 wherein each damping element is coupled between a respective mounting block and the hub body to control pivotable movement of the mounting block, about the respective pivot axis, relative to the hub body.

6. A hub according to any one of the preceding claims wherein each damping element is a dashpot damper.

7. A hub according to Claim 6 wherein the dashpot damper is selected from a group comprising a rubber stopper, a mechanical dashpot damper, an electromagnetic dashpot damper, a hydraulic dashpot damper and a hydrostatic dashpot damper.

8. A hub according to any one of the preceding claims further including a plurality of guides spaced about the outer circumferential surface of the hub body, each guide being arranged to receive and guide pivotable movement of a respective spoke mount about the respective pivot axis, relative to the hub body, and thereby prevent twisting movement of the respective spoke mount relative to the respective pivot axis.

9. A hub according to any one of the preceding claims including three pairs of spoke mounts pivotably mounted about the outer circumferential surface of the hub body so that adjacent pairs of spoke mounts are located 120° apart.

10. A hub according to any one of Claims 1 to 8 including four pairs of spoke mounts pivotably mounted about the outer circumferential surface of the hub body so that adjacent pairs of spoke mounts are located 90° apart.

1 1. A wheel comprising a hub according to any one of the preceding claims, a rim and a plurality of resilient spokes arranged to define pairs of opposed spokes spaced circumferentially around the wheel, each spoke being connected at or towards one end to the hub and at or towards its other end to the rim, and the hub defining an axis of rotation of the wheel that is coincident with the axis of rotation of the hub, wherein the spokes of each pair of opposed spokes are connected to the hub via spoke mounts located on opposite sides of the circumferential hub line and are connected to the rim on a circumferential rim line that extends about an inner circumferential surface of the rim, around the axes of rotation of the wheel and the hub and concentrically aligned with the circumferential hub line, the spokes of each pair of opposed spokes being shaped to follow curved profiles extending towards each other as they extend towards the rim.

12. A wheel according to Claim 11 wherein the spokes of each pair of opposed spokes are connected to the hub via spoke mounts located on opposite sides of the circumferential hub line and mounted for pivotable movement about the same pivot axis, the spokes of each pair of opposed spokes being shaped to extend away from each other as they extend away from the hub and thereafter follow curved profiles extending back towards each other as they extend towards the rim.

13. A wheel according to Claim 11 wherein the spokes of each pair of opposed spokes are connected to the hub via spoke mounts located on opposite sides of the circumferential hub line and mounted for pivotable movement about adjacent pivot axes, the spokes of each pair of opposed spokes being shaped to pass each other as they extend away from the hub and thereafter follow curved profiles extending back towards each other as they extend towards the rim.

14. A wheel comprising a hub, a rim and a plurality of resilient spokes arranged to define pairs of opposed spokes spaced circumferentially about the wheel, each spoke being connected at or towards one end to the hub and at or towards its other end to the rim, the hub including a hub body having a through hole defining coincident axes of rotation of the wheel and hub and a plurality of spoke mounts pivotably mounted in pairs about an outer circumferential surface of the body at locations equidistantly spaced from, and about, the axes of rotation of the wheel and hub, each pair of spoke mounts being mounted for pivotable movement about a common pivot axis extending generally parallel to the axes of rotation of the wheel and hub, wherein the spoke mounts in each pair are mounted about the outer circumferential surface of the hub body so as to be located on opposite sides of a circumferential hub line that extends about the outer circumferential surface of the hub body, around the axes of rotation of the wheel and hub, and wherein the spokes of each pair of opposed spokes are connected to the hub via spoke mounts located on opposite sides of the circumferential hub line and mounted for pivotable movement about adjacent pivot axes, and are connected to the rim on a circumferential rim line that extends about an inner circumferential surface of the rim, around the axes of rotation of the wheel and hub and concentrically aligned with the circumferential hub line, the spokes of each pair of opposed spokes being shaped to pass each other as they extend away from the hub and thereafter follow curved profiles extending back towards each other as they extend towards the rim.

15. A wheel according to Claim 14 wherein the spoke mounts are pivotably mounted about the outer circumferential surface of the hub body by means of mounting axles secured to the hub body about the outer circumferential surface thereof at locations equidistantly spaced from, and about, the axis of rotation of the hub so that each mounting axle extends generally parallel to the axis of rotation of the hub, each pair of spoke mounts being pivotably mounted on a respective mounting axle.

16. A wheel according to Claim 15 wherein each spoke mount includes a mounting block having a through hole to receive a respective mounting axle and a mounting flange extending from the mounting block for connection, in use, to a resilient spoke, the spoke mounts of each pair of spoke mounts being mounted on the respective mounting axle in opposite orientations to each other and so that the spoke mounts mounted on each of the mounting axles, on the same side of the circumferential hub line as each other, are oriented in the same direction.

17. A wheel according to any one of Claims 14 to 16 further including a plurality of damping elements, each damping element being coupled between a respective spoke mount and the hub body to control pivotable movement of the spoke mount, about the respective pivot axis, relative to the hub body.

18. A wheel according to Claim 17 when dependent on Claim 16 wherein each damping element is coupled between a respective mounting flange and the hub body to control pivotable movement of the mounting flange, about the respective pivot axis, relative to the hub body.

19. A wheel according to Claim 17 when dependent on Claim 16 wherein each damping element is coupled between a respective mounting block and the hub body to control pivotable movement of the mounting block, about the respective pivot axis, relative to the hub body.

20. A wheel according to any one of Claims 17 to 19 wherein each damping element is a dashpot damper.

21. A wheel according to Claim 20 wherein the dashpot damper is selected from a group comprising a rubber stopper, a mechanical dashpot damper, an electromagnetic dashpot damper, a hydraulic dashpot damper and a hydrostatic dashpot damper.

22. A wheel according to any one of Claims 1 to 21 further including a plurality of guides spaced about the outer circumferential surface of the hub body, each guide being arranged to receive and guide pivotable movement of a respective spoke mount about the respective pivot axis, relative to the hub body, and thereby prevent twisting movement of the respective spoke mount relative to the respective pivot axis.

23. A wheel according to any one of Claims 14 to 22 including three pairs of spoke mounts pivotably mounted about the outer circumferential surface of the hub body so that adjacent pairs of spoke mounts are located 120° apart.

24. A wheel according to any one of Claims 14 to 22 including four pairs of spoke mounts pivotably mounted about the outer circumferential surface of the hub body so that adjacent pairs of spoke mounts are located 90° apart.

25. A wheel according to any one of Claims 11 to 24 wherein the spokes of each pair of opposed spokes are connected to the rim in an end to end arrangement.

26. A wheel according to Claim 25 wherein the spokes of each pair of opposed spokes are formed integrally with one another.

27. A wheel according to any one of Claims 11 to 26 wherein the profile of each spoke is twisted and connected to the hub and the rim so that the spoke, at or towards the one end, lies in contact with a respective spoke mount along a line that is generally parallel to the axes of rotation of the wheel and the hub, and the spoke at or towards the other end lies in contact with the inner circumferential surface of the rim along a line that is generally parallel to the axes of rotation of the wheel and the hub, and the spoke extends from the respective spoke mount at an angle to the circumferential hub line.

28. A wheel according to Claim 27 wherein the profile of each spoke is twisted and connected to the hub and the rim so that the spoke extends from the rim at an angle to the circumferential rim line.

29. A wheel according to Claim 27 wherein the profile of each spoke is twisted and connected to the hub and the rim so that the spoke extends from the rim along the circumferential rim line.

30. A hub generally as herein described with reference to and or as illustrated in the accompanying drawings.

31. A wheel generally as herein described with reference to and or as illustrated in the accompanying drawings.