GB2554459A

GB2554459A - Wheel assembly

Info

Publication number: GB2554459A
Application number: GB1616552.4A
Authority: GB
Inventors: James Hopton
Original assignee: Energy Technologies Institute LLP
Current assignee: Energy Technologies Institute LLP
Priority date: 2016-09-29
Filing date: 2016-09-29
Publication date: 2018-04-04
Also published as: GB201616552D0; WO2018060669A1

Abstract

A wheel assembly (10), comprising a wheel hub 12 and a tyre 14 that collectively define a substantially fixed volume (16). Further provided is an actuator 18 located within the wheel assembly, such that it separates the fixed volume into a first sub-volume 20 and a second sub-volume 22. The actuator 18 is moveable between a first position and a second position, so as to cause a change of pressure within each of the first sub-volume and the second sub-volume.

Description

(54) Title of the Invention: Wheel assembly

Abstract Title: A wheel assembly comprising a hub, tyre and an actuator separating the tyre inner volume.

(57) Awheel assembly (10), comprising a wheel hub 12 and a tyre 14 that collectively define a substantially fixed volume (16). Further provided is an actuator 18 located within the wheel assembly, such that it separates the fixed volume into a first sub-volume 20 and a second sub-volume 22. The actuator 18 is moveable between a first position and a second position, so as to cause a change of pressure within each of the first sub-volume and the second sub-volume.

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12FIG. 1A

FIG. 1B

At least one drawing originally filed was informal and the print reproduced here is taken from a later filed formal copy.

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Wheel Assembly

Background

The present arrangement relates to a wheel assembly, and particularly an assembly that allows for prolonging the life of a vehicle’s tyre.

It is also desirable to improve vehicle fuel efficiency and performance on different terrains.

Whilst the arrangement can be applied to any vehicle using one or more tyres, the arrangement has particular application to heavy goods vehicles, construction, off-road and/or heavy duty vehicles, or passenger vehicles, such as buses or coaches.

It is known that a partially deflated tyre can achieve greater traction on uneven and/or soft ground. However, manually deflating (and subsequently inflating) the tyres of a vehicle at each interchange between highway and off-road is so time consuming as to be impractical.

The present arrangement seeks to addresses these problems.

Summary of the Invention

The present arrangement adapts the inner volume of the tyre to utilise that fluid (air) already therein. Therefore, in the present arrangement, significant amounts of fluid are not required to be introduced and removed from the tyre to create the pressure changes.

According to the present invention there is provided a wheel assembly, comprising: a wheel hub and a tyre that define a substantially fixed volume, and an actuator located within the wheel assembly, such that it separates the fixed volume into a first sub-volume and a second sub-volume, wherein the actuator is moveable between a first position and a second position, thereby causing a change of pressure within each of the first sub-volume and the second sub-volume.

In the present arrangement, a vehicle’s tyres may be at low relative pressure. This allows it to function in off-road situations, where the greater footprint and tread movement aid traction and grip. By using an actuator to reduce the volume in which the air in the tyre is stored, the pressure in the tyre may be increased. Accordingly, the vehicle can achieve desired on-road performance and fuel efficiency.

Preferably, when the actuator is moved between the first position and the second position, the pressure in the first sub-volume is caused to increase and the pressure in the second sub-volume is caused to decrease.

It is preferred that the actuator is an inflatable element. In a more preferred arrangement, the actuator is un-inflated in its first position, and inflated in its second position. It will be appreciated that these terms are relative to one another; it may be that, in the first position, the actuator is retained in a partially inflated state.

Thus, it is preferred that the actuator defines a third sub-volume, sandwiched between the first and second sub-volumes.

It is preferred that the actuator is inflated by pumping a fluid into it. Preferably the fluid is air, but any suitable liquid or gas will suffice.

The present arrangement is advantageous in that it allows for a considerable change in effective pressure of the tyre, without significant air being pump into, or removed from, the tyre. The only air that needs to be introduced or removed is that in the inflatable actuator.

Preferably a reservoir is housed within the wheel assembly, and particularly in either the tyre cavity, on inside the wheel. It is more preferred that a fluid (preferably either nitrogen or air) from the reservoir is used to inflate the actuator. Fluid from the actuator may be returned to the reservoir when the actuator moves from the second position to the first position.

In an alternative arrangement, a pump may be provided to inflate the actuator 18. The pump may be powered by the vehicle, either from the vehicle engine, vehicle battery or the rotation of the wheel. A dedicated power supply may alternatively be provided.

It is preferred that the actuator surrounds the wheel hub. It is further preferred that the actuator comprises a series of connected 3D elements, and most preferably a series of toroidal segments.

The actuator will typically be constructed from rubber, or similar material. To aid inflation one or more flaps, folds or diaphragms may be provided.

According to a second aspect of the present invention, there is provided a method of increasing the pressure in a tyre of a vehicle, the method comprising:

providing the tyre on a wheel hub such that a volume is defined therein, and filling the volume with a fluid;

compressing the fluid using an actuator.

Preferably the fluid may be compressed whilst the vehicle is in motion. Such an arrangement is desirable as it allows for an efficient transition between on-road and off-road.

It is preferred that the actuator is an inflatable member. Typically, inflating the actuator will compress the fluid in the cavity defined by the wheel hub and the tyre. In preferred arrangements, the actuator is inflated using a reservoir of stored, pressurised fluid. However, a pump arrangement to use air from the atmosphere is also envisaged.

It is preferred that the actuator surrounds the wheel hub.

According to a third aspect of the present invention, there is provided a wheel assembly comprising a tyre with an inflatable member substantially sealed around an inner surface thereof, wherein the inflatable member is operable to be inflated inside the tyre so as to compress a fluid therein.

According to a further aspect of the present invention there is provided a motorised vehicle tyre with an actuating means disposed therein, said actuator configured to compress air within the tyre on increase the operating pressure of the tyre by reducing the volume within which the air is disposed in said tyre.

The various aspects defined above are complementary, and features defined in one may be used in another.

In order that the present invention be more readily understood, specific embodiments thereof will now be described with reference to the accompanying drawings.

Brief Description of the drawings

Figures la and lb shows a wheel assembly in accordance with an embodiment in, respectively, a first and a second operating position.

Figure 2a shows a wheel assembly with a tyre in a high pressure mode.

Figure 2b shows the wheel assembly of figure la, with the tyre in a low pressure mode.

Figure 3 shows a close-up of a section of the wheel assembly of figures la and lb.

Figures 4a, 4b and 4c show arrangements of the actuator in different operating states.

Description of Preferred Embodiments

It is desirable to provide a commercially viable apparatus and method of enabling pressures in tyres of a range of vehicles to be changed to enable the tractive effort of the vehicle to be optimised. Accordingly, the efficiency of the vehicle can be improved for each operating condition, rather than compromised across a range. Furthermore, the tyre pressures of a vehicle directly relate to its rolling resistance, which has an impact on fuel economy.

Optimised operation minimises fuel consumption resulting in minimised vehicle CO₂ emissions.

For a system to be commercially viable, it ideally has to be able to be operated with the vehicle in use; it is not worthwhile if a vehicle operator has to manually inflate and deflate the tyres on each transition from on-road to off-road. If the pressure change is required to be achieved whilst the vehicle is stationary, it is highly desirable that all tyre pressures may be altered substantially simultaneously, and at reasonable speed.

Furthermore, the system is required to be able to initiate a significant number of inflations and deflations - certainly upwards of 50, and ideally nearer 100 - before requiring any servicing or re-charging.

The present arrangement enables a tyre to be inflated and deflated whilst a vehicle is in operation.

It will be appreciated that, in general, the inflating operation presents greater difficulties that the deflating operation.

The arrangement may be applied to any vehicle, although it finds particular application to heavy duty vehicles (HDVs). When an HDV is operating ‘on site’, such as a quarry, mine or construction site, it can be advantageous to have the pressure at approximately 3 bar. Typically, the ground in such an environment is particularly uneven, and may contain loose material, such as mud, gravel or sand. A pressure of 3 bar allows for better grip and traction, because the tyre present a larger footprint, and the tread has greater movement.

When the HDV enters firmer ground, and particularly the public highway, it desirable to return the tyre pressure to around 8 bar. Such pressure allows for greater fuel economy.

Thus, for the optimum efficiency, it is desirable to change the vehicles tyre pressures from 3 bar to 8 bar. Accordingly, to inflate the tyres between these range extremes will require 5 bar to be added to the volume of the tyre cavity. To achieve this be conventional means would require either a sizeable compressor or a large reservoir to make the compressed gas available. Both of these options have considerable drawbacks.

The present embodiment achieves the effect with a fraction of the compressed air that would be required to conventionally fill the tyre.

According to a preferred embodiment, there is provided a wheel assembly 10. The assembly comprises a wheel hub 12 and a tyre 14. A volume 16 is defined by the wheel hub 12 and the tyre 14. Means, such as a valve 62, is typically provided to allow a fluid, such as air, to be introduced therein to bring the tyre 14 up to the desired pressure.

An actuator 18 is further provided. The actuator 18 is located within the volume 16 defined by the wheel hub 12 and the tyre 14. This volume is sometimes referred to as the tyre cavity. The actuator 18 functions to divide the volume 16 in the tyre cavity into two discrete volumes. In figures la and lb these are indicated at 20 (first sub-volume) and 22 (second sub-volume). By moving the actuator 18, the pressure in the sub-volumes may be altered.

In preferred arrangements, the actuator 18 is an inflatable structure. However, it will be appreciated that any arrangement that is operable to move between a first position and a second position so as to alter the pressure in the sub-volumes 20, 22 may be used.

An inflatable actuator 18 forms a third sub-volume 24 within the tyre cavity 16.

Figures la and lb show an embodiment of the present arrangement. Figure la shows the actuator 18 in a deflated position. Figure lb shows the actuator 18 in an inflated position. Accordingly, the pressure in sub-volume 20 is, respectively lower in figure la and higher in figure lb.

An additional representation is shown in figures 2a and 2b, which are described in more detail below.

A fluid reservoir 26 may be provided. The reservoir 26 may be used to store fluid - most preferably either nitrogen or air - that may be used to inflate the actuator 18. Typically, the reservoir 26 is at 20 to 100 bar. In preferred arrangements the reservoir is a semi-rigid housing that may be constructed from nylon or Kevlar®. Of course, other suitable materials may be used.

Appropriate valves to transfer the fluid from the reservoir 26 to the actuator 18 may be provided.

In alternative arrangements, the reservoir 26 may be omitted from the arrangement. An appropriate pump and valve system 80 may be provided instead of, or as well as the reservoir.

Details of the pump system 80 are described further below, particularly with reference to figures 2a and 2b. The pump may be situated on the wheel assembly 10. This is advantageous because it allows the rotation of the wheel assembly 10 to power the pump, and hence, via the valve, introduce air into the actuator 18. However, the pump 80 may be powered by the vehicle’s engine or battery. Alternatively, a dedicated power supply may be provided.

Figure la show the actuator 18 - in this case an inflatable structure - in a deflated state. In this state, the pressures in the various sub-volumes within the tyre are substantially the same. The pressure in the tyre in this arrangement may be set so as to be at relatively low pressure, for use when the vehicle is off-road.

The inflation of the actuator 18 forces the fluid that exists within the cavity to compress into a smaller space and hence increase in pressure. This arrangement is shown in figure lb.

In this arrangement, the pressure in sub-volume 20 is increased, and the pressure in sub-volume 22 is decreased.

In preferred arrangements, the inflatable structure 18 is operable to form an arch whilst compressing the gas that it is displacing. The material used in the actuator 18 has to be flexible to fold, but has to be constructed to hold its arch-like shape as it inflates. Accordingly, the actuator comprises one or more flaps to enable it to inflate in a sequence. A pressurised fluid may be used to inflate the structure. This could be a gas or a liquid, but will typically be nitrogen or air. Figures 4a to 4c show various options, and will be described in further depth below.

Other arrangements may be used to vary the pressure in the first and second sub-volumes 20, 22. For example, instead of an inflatable element, the actuator may comprise an auxetic material material with a negative Poisson’s ratio. In this arrangement a solenoid may be used to active the actuator 18.

Figure 3 shows a cross-section of a wheel hub 12 and a tyre 14. The tyre comprises a bead 60 operable to be received by the wheel hub 12.

A fluid inlet 62, and associated inner tube 72, is provided to allow a fluid, such as air, to be introduced into the tyre.

A reservoir 26 is created by a Kevlar® or nylon structure 64. The structure 64 may comprise a bead 70 to assist sealing. This structure 64 defines, together with the wheel hub 12, a volume. A fluid inlet 66 is provided to allow the reservoir to be filled. This allows the reservoir to be precharge, and also to allow fluid to be introduced thereto by a pumping system.

The actuator 18 is disposed between the fluid inlet 62 and the structure 64. Means 68 to assist sealing may be provided. Typically such means will be a shaped body. Said body could be manufactured from metal, plastic or any other suitable material.

The reservoir 26 and actuator 18 are connected by suitable valve means to allow fluid to be transferred between the two. Such transfer allows the actuator to be inflated and deflated. Accordingly, the fluid in section A of the tyre cavity may be compressed when the actuator in inflated to allow the active pressure in the tyre to in increased.

To ensure that the actuator 18 inflates in a desired and repeatable manner, it is preferred that a one or more folds or flaps or the like are provided. Figure 4a - 4c show examples. Reservoir structure 64 is shown inside actuator 18. In figure 4a, the left-hand side shows the actuator 18 in an expanded state, whilst the right-hand side shows a representation of the actuator in a deflated state.

In preferred arrangements the actuator 18 takes the form of a connected series of toroids surrounding the wheel hub 12. They may be considered as a series of ‘doughnut shaped’ inflatable members.

It is desired that the actuator 18 substantially follows the shape of the inside of the tyre 14. According, the actuator 18 will have vertical sections that follow the tyre sidewall, and a horizontal section that follows the tyre tread.

Figure 4a shows an example of the folds on the horizontal portion. Figure 4b shows the folds along the vertical portion (noting that the left-side would correspond). A hybrid version is shown in figure 4c.

The operation of the wheel assembly will now be described with reference to figures 2a and 2b.

Section X shows a tyre, with three notional sections defined therein: section A, section B and section C. Section Y shows a representation of the assembly used to inflate the actuator 18. This assembly - ie section Y - may be fitted onto a vehicle, and will typically be fitted onto the wheel hub 12.

Figure 2a shows an arrangement with the actuator 18 inflated. In this arrangement, the air in section A is compressed, and hence the tyre is at a high operating temperature. This arrangement is suitable for on-road driving. It will be appreciated that the air in section c will be at below equilibrium pressure.

Figure 2b shows the actuator 18 in a deflated state. The air in section A may expand into a larger volume. Accordingly, the tyre will run at a lower pressure.

In preferred arrangements, each of sections A, B, and C will be at equilibrium pressure in figure 2b. By inflating the actuator, the air in section A is forced into a smaller volume, hence increasing the active pressure in the tyre.

This arrangement is particularly advantageous. A relatively small amount of fluid is required to inflate an actuator. The actuator is used to reduce a volume in a tyre cavity, thereby increasing the relative pressure. Accordingly, introducing a 5 bar increase, as mentioned earlier, does not require significant input of air into, and out of, the tyre, as the actuator achieves the effect by varying the volume.

With reference to figures 2a and 2b, an explanation of the operation of the present system will now be provided.

A compressor 30 is operable to draw a fluid - in preferred arrangements air - either from the atmosphere 100, or from the reservoir 26, or a re-circulation tank 32.

During operation, the compressor 30 fills tank 26 to a pre-determined pressure. Advantageously, this may occur whilst the vehicle is in motion.

Reservoir 26 may be within the wheel structure.

As the vehicle approaches a region which requires the lower pressure, a signal from the operator or detection from a sensor on the vehicle (not shown) causes the tyre 14 to be deflated by releasing the gas in zone B into the re-circulating reservoir 32. Fluid is forced out of the actuator 18 - section B in figures 2a and 2b - due to the mass of the vehicle and/or the load on the tyre 14.

A charge cycle is initiated by compressor 30 drawing the already partially compressed gas stored in re-circulation tank 32, and delivering it, via control valves 34 and 36, to reservoir 26. When this source of compressed gas has been reduced down to atmospheric pressure, valve 66 allows air to be drawn from the atmosphere.

Air inlet 42 (and valve 66) incorporates a shield (not shown) to prevent water ingress.

The compressor 30 continues running until the pressure in the reservoir 26 reaches a predetermined level which is sufficient to enable a pressure charge cycle to take place.

When the operator requires a high tyre pressure setting, the gas from reservoir 26 is discharged via valves 36 and 38 into the inflatable structure 18 (section B). The action of the inflation will compress the gas in section A, and cause pressure below atmospheric (partial vacuum) in section C. If the volume of compressed gas is insufficient to achieve the pressure required the system may channel gas directly from the compressor 30 via valves 34 & 38 to achieve the required inflation pressure.

Once the system has stabilised at high pressure the operation of recharging reservoir 26 commences.

Whilst running at the high pressure, the system monitors the pressure in the tyre 14 and uses valve 50 to lower the pressure if too high and a combination of compressor 30, valve 34 and valve 50 to increase the pressure.

The present arrangement is particularly advantageous in achieving a balance between optimum grip and traction in off-road conditions, and fuel economy in on-road conditions. Also, by always operating with the desired tyre pressures, advantages of lengthened tyre wear and performance are achieved.

It must be stressed that the arrangement is not limited to HDVs. The present arrangement may find use in buses and coaches, where it may be desirable to alter the tyre pressures depending on road conditions. For example, it may be desirable to run the tyres at a higher pressure on the motorway (freeway) than on A or B roads. Fikewise, it may be advantageous to run the tyres at lower pressures in adverse conditions, such as snow.

The present arrangement is also advantageous in that it may be retro-fitted to existing vehicles.

It will be appreciated that the foregoing provides embodiments of the present invention, and that many modifications and variations are possible within the scope of the appended claims.

Claims

1. A wheel assembly, comprising:

a wheel hub and a tyre that define a substantially fixed volume, and an actuator located within the wheel assembly, such that it separates the fixed volume into a first sub-volume and a second sub-volume, wherein the actuator is moveable between a first position and a second position, thereby causing a change of pressure within each of the first sub-volume and the second sub-volume.

2. A wheel assembly according to claim 1, wherein movement of the actuator between the first position and the second position causes the pressure in the first sub-volume to increase and the pressure in the second sub-volume to decrease.

3. A wheel assembly according to claim 1 or claim 2, wherein the actuator is an inflatable element.

4. A wheel assembly according to any preceding claim, wherein the actuator defines a third sub-volume, sandwiched between the first and second sub-volumes.

5. A wheel assembly according to any preceding claim, wherein the actuator is inflated by pumping a fluid therein.

6. A wheel assembly according to any preceding claim, comprising a fluid reservoir housed within the fixed volume.

7. A wheel assembly according to any of claims 1 to 5 comprising a pump configured to inflate the actuator 18.

8. A wheel assembly according to any preceding claim, wherein the actuator surrounds the wheel hub.

9. A method of increasing the pressure in a tyre of a vehicle, the method comprising: providing the tyre on a wheel hub such that a volume is defined therein, and filling the volume with a fluid; and compressing the fluid using an actuator.

10. A method of claim 9, further comprising compressing the fluid whilst the vehicle is in motion.

11. A method of claim 9 or 10, wherein the actuator is an inflatable member.

12. A method of any of claims 9 to 11, wherein the actuator surrounds the wheel hub.

10

13. A wheel assembly comprising a tyre with an inflatable member substantially sealed around an inner surface thereof, wherein the inflatable member is operable to be inflated inside the tyre so as to compress a fluid therein.

14. A motorised vehicle tyre with an actuating means disposed therein, said actuator 15 configured to compress air within the tyre on increase the operating pressure of the tyre by reducing the volume within which the air is disposed in said tyre.

Intellectual

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Application No: Claims searched:

GB1616552.4 1-8 & 13