GB2526314A

GB2526314A - A wheel

Info

Publication number: GB2526314A
Application number: GB1408957.7A
Authority: GB
Inventors: Conor Gray
Original assignee: Dublin Institute of Technology
Current assignee: Dublin Institute of Technology
Priority date: 2014-05-20
Filing date: 2014-05-20
Publication date: 2015-11-25
Also published as: GB201408957D0

Abstract

A wheel 1 comprises a hub 2 and at least one blade element 3. An inner end 5 of each blade element is mounted to the hub, and an outer end 6 of each blade element is movable relative to the hub. The outer end of each blade element may be pivotably movable in the circumferential direction C-C relative to the hub between an expanded diameter configuration and a contracted diameter configuration, thereby the overall outer diameter of the wheel may be varied between a larger overall outer diameter D1 and a smaller overall outer diameter D2. The outer end of each blade element may move relative to the hub in response to a change in angular velocity of rotation of the hub. The wheel may comprise a second hub (11, Fig.4) movable independently of the first hub or the hub may be constructed of a first and second part (21,22, Fig.8), where they may be drawn together or separated by a holding means (26) having a cam contact profile (27).

Description

A wheel

Introduction

This invention relates to a wheel.

Statements of Invention

According to the invention there is provided a wheel comprising: a first hub, and at least one first element extending outwardly from the first hub, at least part of the at least one first element being movable relative to the first hub to vary the diameter of the wheel.

By varying the diameter of the wheel, the invention enables the road holding of a vehicle to be improved. By varying the diameter of the wheel, the invention enables the comfort of a passenger in a vehicle to be improved. By varying the diameter of the wheel, the invention enables enhanced efficiency of a motor in a vehicle to be achieved. For example in the case of deceleration of the wheel, the motor may regenerate braking kinetic energy of the vehicle and store this regenerated energy in a power storage element, such as a battery. For example in the case of acceleration of the wheel, the motor may have lower energy losses, reduced i"2r losses, and less heat generated due to the reduced mechanical ratio of the wheel.

In one embodiment of the invention at least part of the at least one first element is movable relative to the first hub responsive to rotation of the first hub. Preferably at least part of the at least one first element is movable relative to the first hub responsive to a change in rotation of the first hub. This may correspond to an angular acceleration or an angular deceleration of the wheel. Ideally at least part of the at least one first element is movable circumferentially relative to the first hub. Most preferably the at least one first element is pivotably movable relative to the first hub.

A first end of the at least one first element may be mounted to the first hub and a second end of the at least one first element may be movable relative to the first hub.

In another embodiment the at least one first element is movable relative to the first hub between an expanded diameter configuration and a contracted diameter configuration. Preferably the at least one first element is biased towards the expanded diameter configuration.

In one case the wheel comprises a second hub. Preferably the wheel comprises at least one second element extending outwardly from the second hub. Ideally at least part of the at least one second element is movable relative to the second hub to vary the diameter of the wheel, Most preferably at least part of the at least one second element is movable relative to the second hub responsive to rotation of the second hub. At least part of the at least second one element may be movable relative to the second hub responsive to a change in rotation of the second hub. This may correspond to an angular acceleration or an angular deceleration of the wheel, Preferably the first hub is rotatable in a first direction, and the second hub is rotatable in a second direction, the first direction being opposite to the second direction. This arrangement enables the independent control of linear thmst forces and suspension forces.

In another case the first hub comprises a first part and a second part, the first part being movable relative to the second part, Preferably the first part is movable axially relative to the second part. Ideally at least part of the at least one first element is movable relative to the first hub responsive to movement of the first part relative to the second part. This arrangement enables the independent control of linear thrust forces and suspension forces. Most preferably the first part is movable relative to the second part between a first configuration in which the first part is located frirther apart from the second part, and a second configuration in which the first part is located closer to the second part. The first part and/or the second part may be biased towards the second configuration. Preferably the first hub comprises means to selectively hold the first part and/or the second part in the first configuration. Ideally the holding means is movable relative to the first part and/or the second part to facilitate movement of the first part relative to the second part between the first configuration and the second configuration. Most preferably the holding means is rotatable relative to the first part and/or the second part. The holding means may be engagable with the first part and/or the second part. Preferably an engagement surface of the holding means is cam-shaped. Ideally an engagement surface of the first part and/or the second part is cam-shaped.

In one embodiment at least part of the at least one first element is movable radially relative to the first hub. Preferably a first end of the at least one first element is mounted to the first hub and a second end of the at least one first element is mounted to the first hub. Ideally a portion of the at least one first element between the first end and the second end is movable relative to the first hub.

The invention also provides in another aspect a vehicle comprising a wheel of the invention.

By varying the diameter of the wheel, the invention enables the road holding of the vehicle to be improved. By varying the diameter of the wheel, the invention enables the comfort of a passenger in the vehicle to be improved.

In one embodiment of the invention the vehicle comprises a motor. By varying the diameter of the wheel, the invention enables enhanced efficiency of the motor in the vehicle to be achieved. Preferably the vehicle comprises means to regenerate braking energy. Ideally the vehicle comprises means to store regenerated braking energy. For example in the case of deceleration of the wheel, the motor may regenerate the braking kinetic energy of the vehicle and store this regenerated energy in the power storage element, such as a battery. Most preferably the vehicle comprises an automobile.

Brief Description of the Drawings

The invention will be more clearly understood from the following description of some embodiments thereof given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is an isometric view of a wheel according to the invention, Fig. 2 is an isometric view of the wheel of Fig. I decelerating in use, Fig. 3 is an isometric view of the wheel of Fig. I accelerating in use, Fig. 4 is an isometric view of another wheel according to the invention, Fig. 5 is an isometric view of part of the wheel of Fig. 4, Fig. 6 is an isometric view of the wheel of Fig. 4 decelerating in use, Fig. 7 is an isometric view of the part of Fig. 5 decelerating in use, Fig. 8 is an isometric view of another wheel according to the invention in a first configuration, Fig. 9 is an isometric view of part of the wheel of Fig. 8 in the first configuration, Fig. 10 is an isometric view of the wheel of Fig. 8 in a second configuration, and Fig. 11 is an isometric view of the part of Fig. 9 in the second configuration.

Detailed Description

Referring to the drawings, and initiafly to Figs. I to 3 thereof, there is illustrated a wheel 1 according to the invention. The wheel 1 is suitable for use as part of a vehicle, such as an automobile.

The vehicle may comprise a motor, means to regenerate braking energy, and means to store such regenerated braking energy.

The wheel comprises a first hub 2, and a plurality of first blade elements 3, The hub 2 has an axial direction A-A, a radial direction R-R, and a circumferential direction C-C. The hub 2 is rotatable around the axis A-A in the circumferential direction C-C.

The plurality of blade elements 3 are evenly spaced apart around the circumference of the hub 3. Each of the blade elements 3 extends outwardly from the hub 2. An inner end 5 of each blade element 3 is mounted to the hub 2, and an outer end 6 of each blade element 3 is movable relative to the hub 2, as illustrated in Figs. 2 and 3. In this manner the outer end 6 of each blade element 3 is pivotably movable in the circumferential direction C-C relative to the hub 2 between an expanded diameter configuration (Fig. 1) and a contracted diameter configuration (Figs. 2 and 3). Each blade element 3 is movable in the anti-clockwise direction relative to the hub 2 as illustrated in Fig. 2, or in the clockwise direction relative to the hub 2 as illustrated in Fig. 3.

By pivotably moving the outer ends 6 of the blade elements 3 relative to the hub 2, the overall outer diameter of the wheel 1 may be varied between the expanded diameter configuration with a larger overall outer diameter Di (Fig. 1), and the contracted diameter configuration with a smaller overall outer diameter D2 (Figs. 2 and 3). Dl is greater than D2. In this case the blade elements 3 are biased towards the expanded diameter configuration of Fig. I. The outer end 6 of each blade element 3 is caused to move relative to the hub 2 in response to a change in angular velocity of rotation of the hub 2. For example in the case where the hub 2 is rotating in the anti-clockwise direction. In the event of a deceleration force being applied to the hub 2 with a reduction in angular velocity of rotation of the hub 2, the outer end 6 of each blade element 3 is caused to pivotably move in the anti-clockwise circumferential direction C-C relative to the hub 2 between the expanded diameter configuration (Fig. I) and the contracted diameter configuration (Fig. 2). For example in the case where the wheel 1 is stationary. In the event of an acceleration force being applied to the hub 2 in the anti-clockwise direction with an increase in angular velocity of rotation of the hub 2, the outer end 6 of each blade element 3 is caused to pivotably move in the clockwise circumferential direction C-C relative to the hub 2 between the expanded diameter configuration (Fig. I) and the contracted diameter configuration (Fig. 3).

The hub 2 may be provided in the form of a drum. Figs. Ito 3 illustrate the single centre drum hub 2 with the outer diameter controlled by acceleration and deceleration which allows for more efficient operation and less heat generation. The wheel 1 comprises the central drum hub 2, The wheel 1 has the number of radial flat blade spokes 3 evenly spaced around the circumference of the drum hub 2, radiating outwards, The radial flat blades 3 are attached at one end of the drum hub 2, using the pivotal joint which allows the distance between the outer tip 6 of the blade 3 and the central axis A-A to increase as the central drum hub 2 rotates.

In use, when the hub 2 is rotating in the anti-clockwise direction, and a deceleration force is applied to the hub 2 with a reduction in angular velocity of rotation of the hub 2, the outer end 6 of each blade element 3 pivotably moves in the anti-clockwise circumferential direction C-C relative to the hub 2 from the expanded diameter configuration (Fig. 1) to the contracted diameter configuration (Fig. 2). In this manner the overall outer diameter of the wheel I is reduced to D2. When the deceleration force ceases to be applied to the hub 2 with a return to a constant angular v&ocity of rotation of the hub 2, the blade elements 3 are biased back towards the expanded diameter configuration of Fig. 1. Therefore the outer end 6 of each blade element 3 pivotably moves in the clockwise circumferential direction C-C relative to the hub 2 from the contracted diameter configuration (Fig. 2) back to the expanded diameter configuration (Fig. t). In this manner the overall outer diameter of the wheel 1 is increased again to DI.

When the wheel 1 is stationary, and an acceleration force in the anti-clockwise direction is applied to the hub 2 with an increase in angular velocity of rotation of the hub 2, the outer end 6 of each blade element 3 pivotably moves in the clockwise circumferential direction C-C relative to the hub 2 from the expanded diameter configuration (Fig. I) to the contracted diameter configuration (Fig. 3), In this manner the overall outer diameter of the wheel I is reduced to D2. When the acceleration force ceases to be applied to the hub 2 with a return to a constant angular velocity of rotation of the hub 2, the blade elements 3 are biased back towards the expanded diameter configuration of Fig. 1. Therefore the outer end 6 of each blade element 3 pivotably moves in the anti-clockwise circumferential direction C-C relative to the hub 2 from the contracted diameter configuration (Fig. 3) back to the expanded diameter configuration (Fig. 1). In this manner the overall outer diameter of the wheel 1 is increased again to D I. In Fig. 1 the wheel I is travelling in the anti-clockwise direction. When no torque is applied to the centre hub 2, for example freewheeling or at rest, the distance between the blade tip 6 and the centre axis A-A is at a maximum, which results in the wheel 1 having maximum diameter Dl. Fig. 1 illustrates the frilly expanded wheel 1 with zero torque applied to the centre hub 2.

In Fig. 2 the wheel I is travelling in the anti-clockwise direction. When braking is applied to the centre hub 2, for example negative torque, which allows the distance between the outer tip 6 of the blade 3 and the central axis A-A to decrease, which results in the overall diameter of the wheel contracting. A smaller diameter wheel is advantageous when decelerating as it allows the motor operating in regeneration mode to operate more efficiently. During braking the kinetic energy of the vehicle is regenerated back into the batteries via the motor operating as a generator. Fig. 2 illustrates the frilly contracted wheel following deceleration.

In Fig. 3 the wheel I is ftavelling in the anti-clockwise direction. When accelerating torque is applied to the centre hub 2, for example positive torque, which allows the distance between the outer tip 6 of the blade 3 and the central axis A-A to decrease, which results in the overall diameter of the wheel I contracting. A smaller diameter wheel is advantageous when accelerating as it allows the motor to operate more efficiently due to the reduced mechanical ratio, thereby reducing the iA2r losses in the motor which means less heat generated and also more efficient operation. Fig. 3 illustrates the frilly contracted wheel I when accelerating.

In Figs, 4 to 7 there is illustrated another wheel 10 according to the invention, which is similar to the wheel 1 of Figs. ito 3, and similar elements in Figs. 4 to 7 are assigned the same reference numerals.

In this case in addition to the first hub 2, the wheel 10 also comprises a second hub ii, and a plurality of second blade elements 12.

The second hub 11 has the same axial direction A-A, the same radial direction R-R, and the same circumferential direction C-C as the first hub 2. The second hub 11 is rotatable around the axis A-A in the circumferential direction C-C similar to the first hub 2. However the first hub 2 and second hub 11 are configured to rotate in opposite directions.

Each of the second blade elements 12 extends outwardly from the second hub 11. An inner end of each second blade element 12 is mounted to the second hub 11, and an outer end of each second blade element 12 is movable relative to the second hub II.

In this manner the outer end of each second blade element 2 is pivotably movable in the circumferential direction C-C relative to the second hub 11 between an expanded diameter configuration (Fig. 4) and a contracted diameter configuration (Fig. 6).

Each second blade element 12 is movable in the anti-clockwise direction relative to the second hub 11, or in the clockwise direction relative to the second hub 11 as illustrated in Fig. 6.

By pivotably moving the outer ends of the second blade elements 12 relative to the second hub 11, the overall outer diameter of the wheel 10 may be varied between the expanded diameter configuration with the larger overall outer diameter D (Fig, 4), and the contracted diameter configuration with the smaller overall outer diameter D2 (Fig. 6). In this case the second blade elements 12 are biased towards the expanded diameter configuration of Fig. 4.

The outer end of each second blade element 12 is caused to move r&ative to the second hub II in response to a change in angular velocity of rotation of the second hub 11. For example in the case where the second hub 11 is rotating in the clockwise direction. In the event of a deceleration force being applied to the second hub 11 with a reduction in angular velocity of rotation of the second hub ii, the outer end of each second blade element 12 is caused to pivotably move in the clockwise circumferential direction C-C relative to the second hub it between the expanded diameter configuration (Fig. 4) and the contracted diameter configuration (Fig. 6). For example in the case where the second hub 11 is stationary. In the event of an acceleration force being applied to the second hub 11 in the clockwise direction with an increase in angular velocity of rotation of the second hub 11, the outer end of each second blade element 12 is caused to pivotably move in the anti-clockwise circumferential direction C-C relative to the second hub 11 between the expanded diameter configuration and the contracted diameter configuration.

Each hiade element 3, 12 may be provided in the form of a radial flat blade spoke.

Figs. 4 to 7 illustrate the counter rotating drum hubs 2, II to allow for independent control of linear thrust forces and suspension forces. The wheel 10 comprises the two drum hubs 2, 11, with 2 being the outer drum hub and 11 being the inner drum hub.

Each drum hub 2, ii has the number of radial flat blade spokes 3, 12 respectively evenly spaced around the circumference of the drum hub 2, , radiating outwards, With the drum hub 2, the flat blade spokes 3 are tangential in one direction while in drum hub 11, the flat blade spokes 12 are tangential in the opposite direction. The radial flat blade spokes 3, 12 are aftached at one end of the drum hub 2, 11, using a pivotal joint which allows the distance between the outer tip of the fiat blade spokes 3, 12 and the central axis A-A to increase as the central drum hubs 2, 11 rotate. The drum hubs 2, II are independently driven with respect to one another: The drum hubs 2, 11 are always rotating in opposite directions with respect to one another.

In Fig, 4 the drum hubs 2, ii are shown in phase with each other, resulting in maximum expansion of the distance between the tips of the fiat blade spokes and the centre axis A-A. Here the two lines on the inside of the drum hubs 2, 11 are aligned.

This has the net effect of an increased diameter wheel 10. Figs, 4 and 5 illustrate the frilly expanded wheel 10 with 0 degrees phase shift.

In Fig, 6 the drum hubs 2, 11 are shown out of phase with each other, resulting in maximum contraction of the distance between the tips of the flat blade spokes and the centre axis A-A. The relative orientation of the two lines on the inside of the drum hubs 2, 11 represents the phase shift between the drum hubs 2, 11. This has the net effect of a reduced diameter wheel 10. Figs. 6 and 7 illustrate the frilly contracted wheel 10 with 90 degrees phase shifted. 1]

In use, when the second hub 11 is rotating in the clockwise direction, and a deceleration force is applied to the second hub 11 with a reduction in angular velocity of rotation of the second hub II, the outer end of each second blade element 12 pivotably moves in the clockwise circumferential direction C-C relative to the second hub 11 from the expanded diameter configuration (Fig. 4) to the contracted diameter configuration (Fig. 6). In this manner the overall outer diameter of the wheel 10 is reduced to D2. When the deceleration force ceases to be applied to the second hub 11 with a return to a constant angular velocity of rotation of the second hub 11, the second blade elements 12 are biased back towards the expanded diameter configuration of Fig. 4. Therefore the outer end of each second blade element 12 pivotably moves in the anti-clockwise circumferential direction C-C relative to the second hub t t from the contracted diameter configuration (Fig. 6) back to the expanded diameter configuration (Fig. 4), In this manner the overall outer diameter of the wheel 10 is increased again to Dl.

When the second hub 11 is stationary, and an acceleration force is applied to the second hub 11 in the clockwise circumferential direction C-C with an increase in angular velocity of rotation of the second hub ii, the outer end of each second blade element 12 pivotably moves in the anti-clockwise circumferential direction C-C relative to the second hub 11 from the expanded diameter configuration to the contracted diameter configuration. In this manner the overall outer diameter of the wheel lOis reduced to D2. When the acceleration force ceases to be applied to the second hub 11 with a return to a constant angular velocity of rotation of the second hub 11, the second blade elements 12 are biased back towards the expanded diameter configuration of Fig. 4. Therefore the outer end of each second blade element t2 pivotably moves in the clockwise circumferential direction C-C relative to the second hub It from the contracted diameter configuration back to the expanded diameter configuration. In this manner the overall outer diameter of the wheel 10 is increased again to Dl.

Figs. 8 to 11 illustrate a frirther wheel 20 according to the invention, which is similar to the wheel 1 of Figs. 1 to 3, and similar elements in Figs. 8 to 11 are assigned the same reference numerals.

In this case the first hub 2 comprises a first ring part 21, a second ring part 22, and a holder ring part 26. The holder ring part 26 is located between the first ring part 2! and the second ring part 22. The holder ring part 26 is engagab!e with the first ring part 21 and the second ring part 22. The holder ring part 26 has a cam-shaped engagement surface on a first side 27 facing the first ring part 21, aiid has a cam-shaped engagement surface on a second side 28 facing the second ring part 22. The first ring part 21 has a corresponding cam-shaped engagement surface on a side 29 facing the holder ring part 26. Similarly the second ring part 22 has a corresponding cam-shaped engagement surface on a side 30 facing the holder ring part 26.

The first ring part 21 is movable in the axial direction A-A relative to the second ring part 22 between a first configuration in which the first ring part 21 is located further apart from the second ring part 22 (Figs. 8 and 9), and a second configuration in which the first ring part 21 is located closer to the second ring part 22 (Figs. 10 and ii).

The first ring part 21 and the second ring part 22 are biased towards the second configuration. The holder ring part 26 acts to selectively hold the first ring part 2 and the second ring part 22 in the first configuration. The holder ring part 26 is rotatable in the circumferential direction C-C relative to the first ring part 21 and the second ring part 22 to facilitate movement of the first ring part 21 relative to the second ring part 22 between the first configuration (Figs. 8 and 9) and the second configuration (Figs. 10 and 11), A first end 23 of each first b!ade element 3 is mounted to the first ring part 21 and a second end 24 of each first blade element 3 is mounted to the second ring part 22 (Fig. 9). A central portion 25 of each blade element 3 located between the first end 23 and the second end 24 is movable radially relative to the hub 2.

The central portion 25 of each blade element 3 is caused to move relative to the hub 2 S in response to the first ring part 21 moving in the axial direction A-A relative to the second ring part 22 between the first configuration and the second configuration.

By moving the central portions 25 of the blade elements 3 relative to the hub 2, the overall outer diameter of the wheel 20 may be vaiied between the expanded diameter configuration with the larger overall outer diameter Dl (Fig. 10), and the contracted diameter configuration with the smaller overail outer diameter D2 (Fig. 8). Dl is greater than D2.

Figs. 8 to 11 illustrate the three drum hub cross spoke wheel 20 which allows for independent control of linear thrust forces and suspension forces. The wheel 20 comprises the three drum hubs, denoted as 21, 22, 26 with 21 being the outer drum hub and 26 being the middle drum hub and 22 being the inner drum hub. Drum hub 21 and drum hub 22 rotate in unison with each other, the phase between the two not varying, Drum hub 21 and drum hub 22 are identical and are placed on the same axis A-A in miror image to each other. Drum hub 21 and 22 are driven by the same motor, the only movement they can have rehttive to one another is axial movement.

Drum hub 21 and drum hub 22 have a flat outer edge, with the inner edges 29, 30 respectively forming a repetitive sinusoidal pattern. The same sinusoidal pattern is present on both sides 27, 28 of the drum hub 26. The series of flexible spokes 3 are attached to the outer sides of the drum hub 2 t and the drum hub 22 straddling the wheel 20. These spokes 3 are flexible.

In Fig. 8 the drum hubs 21 and 22 are in phase with each other, and both of these drum hubs 21 and 22 are out of phase with the centre drum hub 26 by an angle approaching 180 degrees. This results in maximizing the wheel width in the axial direction and thus reducing the distance between the spoke outer tip 25 and the central axis A-A which ultimately results in reduction of the overall diameter.

In Fig. 10 the drum hubs 21 and 22 are in phase with each other, they are also in phase with the centre drum hub 26. This resulls in minimizing the wheel width in the axial direction and thus increasing the distance between the spoke outer tip 25 and the central axis A-A which ultimately results in the increase of the overall diameter.

In use, the holder ring part 26 is rotated in the circumferential direction C-C relative to the first ring part 21 and the second ring part 22. Because the first ring part 21 and the second ring part 22 are biased towards the second configuration, this rotation allows the first ring part 21 to move in the axial direction A-A relative to the second ring part 22 from the first configuration (Figs. 8 arid 9) to the second configuration (Figs, 0 and 11). The movement of the first ring part 21 in the axial direction A-A relative to the second ring part 22 from the first configuration to the second configuration causes the central portion 25 of each blade element 3 to move radially outwardly relative to the hub 2. In this manner the overall outer diameter of the wheel 20 is increased from the contracted diameter configuration with the smaller overall outer diameter D2 (Fig. 8), to the expanded diameter configuration with the larger overall outer diameter Dl (Fig. 10).

The holder ring part 26 is then further rotated in the circumferential direction C-C relative to the first ring part 21 and the second ring part 22. Because the cam-shaped engagement surfaces 27, 28 engage against the corresponding cam-shaped engagement surface 29 of the first ring part 21 and the corresponding cam-shaped engagement surface 30 of the second ring part 22, this rotation forces the first ring part 21 to move in the axial direction A-A relative to the second ring part 22 from the second configuration (Figs. 10 and 11)to the first configuration (Figs. 8 and 9). The movement of the first ring part 21 in the axial direction A-A relative to the second ring part 22 from the second configuration to the first configuration causes the central portion 25 of each blade element 3 to move radially inwardly relative to the hub 2. In this maimer the overall outer diameter of the wheel 20 is decreased from the expanded diameter configuration with the larger overall outer diameter Dl (Fig. 10), to the contracted diameter configuration with the smaller overall outer diameter D2 (Fig. 8).

The invention is not limited to the embodiments hereinbefore described, with reference to the accompanying drawings, which may be varied in construction and detail.

Claims

Claims 1 A wheel comprising: a first hub, and at least one first element extending outwardly from the first hub, at least part of the at least one first element being movable relative to the first hub to vary the diameter of the wheel.
2. A wheel as claimed in claim 1 wherein at least part of the at least one first element is movable relative to the first hub responsive to rotation of the first hub.
3, A wheel as claimed in claim 2 wherein at least part of the at least one first element is movable relative to the first hub responsive to a change in rotation of the first hub.
4. A wheel as claimed in any of claims Ito 3 wherein at least part of the at least one first element is movable circumferentiafly relative to the first hub.
S. A wheel as claimed in any of claims 1 to 4 wherein the at least one first element is pivotably movable relative to the first hub.
6. A wheel as claimed in any of claims 1 to 5 wherein a first end of the at least one first element is mounted to the first hub arid a second end of the at least one first element is movable relative to the first hub.
7. A wheel as claimed in any of claims 1 to 6 wherein the at least one first element is movable relative to the first hub between an expanded diameter configuration and a contacted diameter configuration.
8. A wheel as claimed in claim 7 wherein the at least one first element is biased towards the expanded diameter configuration.
9. A wheel as claimed in any of claims 1 to 8 wherein the wheel comprises a second hub.
10. A wheel as claimed in claim 9 wherein the wheel comprises at least one second element extending outwardly from the second hub.
11, A wheel as claimed in claim 0 wherein at least part of the at least one second element is movable relative to the second hub to vary the diameter of the wheel.
12. A wheel as claimed in claim 11 wherein at least part of the at least one second element is movable relative to the second hub responsive to rotation of the second hub.
13. A wheel as claimed in claim 2 wherein at least part of the at least second one element is movable relative to the second hub responsive to a change in rotation of the second hub.
14. A wheel as claimed in claim 12 or 13 wherein the first hub is rotatable in a first direction, and the second hub is rotatable in a second direction, the first direction being opposite to the second direction.
15. A wheel as claimed in any of claims 1 to 14 wherein the first hub comprises a first part and a second part, the first part being movable relative to the second part.
16. A wheel as claimed in claim 15 wherein the first part is movable axially relative to the second part.
17. A wheel as claimed in claim 15 or 16 wherein at least part of the at least one first element is movable relative to the first hub responsive to movement of the first part relative to the second part.
18 A wheel as claimed in any of claims 15 to 17 wherein the first part is movable relative to the second part between a first configuration in which the first part is located further apart from the second part, and a second configuration in which the first part is located closer to the second part.
19. A wheel as claimed in claim 18 wherein the first part and/or the second part is biased towards the second configuration.
20, A wheel as claimed in claim 8 or 19 wherein the first hub comprises means to selectively hold the first part and/or the second part in the first configuration.
21. A wheel as claimed in claim 20 wherein the holding means is movable relative to the first part and/or the second part to facilitate movement of the first part relative to the second part between the first configuration and the second configuration.
22, A wheel as claimed in claim 2 wherein the holding means is rotatable relative to the first part and/or the second part.
23. A wheel as claimed in any of claims 20 to 22 wherein the holding means is engagable with the first part and/or the second part.
24. A wheel as claimed in claim 23 wherein an engagement surface of the holding means is cam-shaped.
25. A wheel as claimed in claim 23 or 24 wherein an engagement surface of the first part and/or the second part is cam-shaped.
26. A wheel as claimed in any of claims 15 to 25 wherein at least part of the at least one first element is movable radially relative to the first hub.
27. A wheel as claimed in any of claims 15 to 26 wherein a first end of the at least one first element is mounted to the first hub and a second end of the at least one first element is mounted to the first hub.
28. A wheel as claimed in claim 27 wherein a portion of the at least one first element between the first end and the second end is movable relative to the first hub.
29. A wheel substantially as hereinbefore described with reference to the accompanying drawings.
30. A vehicle comprising a wheel as claimed in any of claims 1 to 29.
31. A vehicle as claimed in claim 30 wherein the vehicle comprises a motor.
32. A vehicle as claimed in claim 30 or 31 wherein the vehicle comprises means to regenerate braking energy. U,
33. A vehicle as claimed in any of claims 30 to 32 wherein the vehicle comprises means to store regenerated braking energy.
34, A vehicle as claimed in any of claims 30 to 33 wherein the vehicle comprises an automobile.
35. A vehicle substantially as hereinbefore described with reference to the accompanying drawings.