WO2005095124A2

WO2005095124A2 - Wheel rim well band for runflat tyre

Info

Publication number: WO2005095124A2
Application number: PCT/ZA2004/000132
Authority: WO
Inventors: Geoffrey Charles Wolf; William Athol Alexander; John Ernest Simpson
Original assignee: Geoffrey Charles Wolf; William Athol Alexander; John Ernest Simpson
Priority date: 2003-10-31
Filing date: 2004-11-01
Publication date: 2005-10-13
Also published as: WO2005095124A3

Abstract

An elastomeric wheel well filler band (10) having a radially inner surface that is formed with at least one circumferential groove (28), preferably with two grooves (28), and is dimensioned substantially to span the well (16) of a wheel rim (12). The wheet well filler band (10) is formed by extrusion, wherein the ends are joined by an suitable adhesive. Preferably, the both join ends of the band are beveled at an angle of 45 degrees in the circumferential direction.

Description

RUN FLAT WHEEL BAND

TECHNICAL FIELD: This invention relates to run flat wheel bands that are fitted to a wheel rim on which a pneumatic tyre is mounted in order to prevent the tyre beads from separating from the wheel rim when the tyre loses pressure. The invention is concerned primarily with such bands of the type referred to in the art as "wheel well fillers".

BACKGROUND ART:

Pneumatic tyres have reinforced, substantially inextensible beads that engage the inner sides of a flange provided on each side of the periphery of a wheel rim to hold the tyre on the rim when it is pressurised. In order to fit the tyre to the rim it is necessary first to lever one of the beads over a rim flange, then move that bead longitudinally across the rim until it can seat in a wheel well, or annular groove on the wheel rim, and then lever the other bead over the same flange. Inflating the tyre causes both beads to move away from each other and seat against the flanges. The wheel well facilitates fitting the tyre and enables pneumatic inner tubes and the like also to be fitted if required. In the event of loss of air, say because of a puncture, the beads are free to move away from the flanges. Should one of the beads move into the wheel well, then it is possible and often likely that the other bead will have sufficient freedom to move over its adjacent flange. The vehicle then rides on the rim. This is dangerous and can be fatal at high speeds.

Wheel well fillers comprising one or more arcuate bands that can be joined to each other to fill the well are known. They work effectively, but can be difficult to fit and with ageing over time can be extremely difficult to remove and refit, especially with low profile tyres. US patent 4,076,067 describes a cast or moulded solid elastomeric band wheel well filler that can be stretched over the flanges. This band is then used with a special purpose wheel rim configured such that the band seats beneath one of the beads of the tyre. Longitudinally extending metal reinforcements at circumferentially spaced intervals are used to ensure the band does not separate from the well under centrifugal forces in use. US Patent 4,293,016 describes a cast, high modulus elastomer, channel section band that is a tread supporter and bead holder rather than a wheel well filler and that relies on its configuration, engagement with the tyre beads and stiffness to resist centrifugal forces. This band is extremely difficult to fit and is expensive because of the materials and configuration used.

Thus the invention seeks to provide a wheel well filler that is easy to fit and remove, can be manufactured inexpensively and does not require special wheel rims, configurations or after-fitment components to enable it to perform satisfactorily at the speed limits in most countries.

DISCLOSURE OF THE INVENTION: One aspect of the invention provides an elastomeric wheel well filler band having a radially inner surface that is formed with at least one circumferential groove and is dimensioned substantially to span the well of a wheel rim.

Preferably the band is formed with two spaced grooves in its radially inner surface.

Another aspect of the invention provides an elastomeric wheel well filler band comprising a strip of elastomer formed into an endless band, with the ends of the band bonded to each to each other by a suitable adhesive.

Preferably the strip of elastomer is formed by extrusion.

Preferably the ends are complementally bevelled, so as to maximise their mutual contact surface area and ensure the adhesive bond acts in shear rather than pure tension. Preferably the bevel extends in the direction of the circumference of the band. Preferably the bevel extends at between 20 and 70° to the length of the strip forming the band, more preferably between 30 and 60°, and optimally at about 45° for ease of manufacture.

Preferably the elastomer comprises a natural rubber. Pure natural rubber may be used, but it is preferred, for an acceptable compromise between cost and performance, to use a blend of natural rubber, filler and oil to provide a satisfactory tear strength, tensile strength, elasticity and hardness.

Preferably characteristics of the elastomer are at least one of: - tensile strength of at least 5 MpA, preferably at least 15 MpA and optimally in the range of 18 to 20 MpA; elasticity greater than 100% and preferably greater than 500%; and hardness of at least 50 Shore, more preferably in the range of 60 to 70 Shore.

A blend of 50 to 70% rubber, 25 to 35% filler and 5 to 15% oil is preferred, with about 60% rubber, about 30% filler and about 10% oil having been found to be an acceptable balance of characteristics, cost and workability.

Further features, variants and/or advantages of the invention will emerge from the following non-limiting description of an example of the invention made with reference to the accompanying schematic drawings.

BRIEF DESCRIPTION OF THE DRAWINGS:

Figure 1 shows a section through a portion of wheel rim with a well filler band of the invention filling a well in the rim; Figure 2 shows a perspective view of an extruded section used to form the band of Figure 1 ; Figure 3 shows a side view of the band of Figure 1 ; and

Figure 4 shows a section of a band suitable for use with narrow wheel wells.

DESCRIPTION OF ILLUSTRATED EMBODIMENTS:

In the drawings a wheel well filler band 10 of the invention is fitted to a wheel rim 12.

The wheel rim 12 comprises a hub portion 14 and a rim portion 16 formed with a wheel well 18 and opposed tyre bead retaining side flanges 20. The band 10 is seated in the wheel well rim portion 16 has a web 18.

The band 10 is formed by joining the ends of an extruded strip of natural rubber, filler and oil that has been vulcanised. As shown in Figure 3, the join is made by cutting the ends of the strip at a slant or bevel of about 45° and joining then together at 11. The strip has a substantially flat upper or radially outermost surface 22, opposed shoulders 24 and three spaced truncated conical ribs 26 that define two grooves 28 between one another. An overhang 30 is formed between each shoulder and the rib adjacent to it.

The rib and groove formations provide the band with a thickness or depth that gives it strength and stiffness, while minimising its mass. The formations, especially the outer ribs and shoulder overhang, also enable the band to flex to fit into most shapes of wheel well that are commonly used. Figure 4 shows another shape of band 10.1 of the invention suitable for so called "narrow" wheel wells that are sometimes used - in this event the outer ribs are closer to each other and slightly shorter than those of the band 10. The rib formation also facilitates cutting away portions of either the central rib or the central rib and one of the side ribs to enable a tyre valve to be fitted for those wheel rims that have the tyre valve opening in the wheel well.

In practice, the bands 10 are fitted to and removed from a wheel rim using the commonly available machines used for fitting tyres to the rim. Thus no additional expertise or specialised equipment is required to fit or remove the band, nor is there the possibility that the band has not been fitted properly or secured and tensioned adequately as with know wheel fillers.

An important aspect of the invention is that the diameter of the band is selected such that when installed on a particular size wheel rim, the band is under sufficient tension to enable it to be driven up to satisfactorily high speeds without the danger of it distorting radially under centrifugal forces to a significant extent. Typically, the tension will be such that the band remains in the wheel well up to about 25% above the statutory maximum speed. For example, in South Africa the maximum statutory speed is 120 km/h, so the band will be tensioned to remain seated in the well up to about 150 km/h. Different diameter bands are made for 13", 14" ... 21" wheels. Exceeding that speed will cause the band to distort, in which event the wheel will become unstable and will vibrate warning the driver to slow down. Bands capable of being driven to higher speeds can be made, either by decreasing the diameter of the unstressed band so that is under a higher tension when installed or by modifying the composition of the material of the band so that it is stiffer, i.e. has a higher elastic coefficient.

While the driver of a vehicle fitted with the bands will know of the speed limitations, another driver may be unaware. The inventor thus further proposes that each wheel fitted with the tyre band be clearly marked as such, e.g. by painting a large bright, red, yellow, white, etc. dot or circle or other shape on the outside of each tyre and by providing a visible marking on the windscreen, dashboard or steering wheel. An important aspect of the invention is the realisation by the inventor that the band does not need to be made for the highest potential speed at which a vehicle on which it is mounted will be driven, merely sufficient for normal usage and optionally coupled with suitable warning indicia. This enables the band to be made economically, fitted without difficulty, and sold at an acceptable price where the life saving and danger reducing benefits will outweigh the possible speed limitations it may impose.

The invention is not limited to the precise details described above and shown in the drawings. Modifications may be made and other embodiments developed without departing from the spirit of the invention. For example, the material of the band may be made of other rubbers and rubber blends, such as synthetic rubbers if desired. Also the band may be cast or moulded.

Claims

CLAIMS:

1. An elastomeric wheel well filler band having a radially inner surface that is formed with at least one circumferential groove and is dimensioned substantially to span the well of a wheel rim.

2. The band of claim 1, wherein the band is formed with two spaced grooves in its radially inner surface.

3. An elastomeric wheel well filler band comprising a strip of elastomer formed into an endless band, with the ends of the band bonded to each to each other by a suitable adhesive.

4. The band of claim 3, wherein the strip of elastomer is formed by extrusion.

5. The band of either of claims 3 or 4, wherein the ends are complementally bevelled.

6. The band of claim 5, wherein the bevel extends in the direction of the circumference of the band.

7. The band of either of claims 5 or 6, wherein the bevel extends at between 20 and 70° to the length of the strip forming the band.

8. The band of either of claims 5 or 6, wherein the bevel extends at between

30 to 60° to the length of the strip forming the band.

9. The band of either of claims 5 or 6, wherein the bevel extends at between about 45° to the length of the strip forming the band.

10. The band of any preceding claim, wherein the elastomer comprises a natural rubber.

11. The band of any preceding claim, wherein the elastomer comprises a blend of natural rubber, filler and oil to provide a satisfactory tear strength, tensile strength, elasticity and hardness.

12. The band of any preceding claim, wherein the elastomer has a tensile strength of at least 5 MpA.

13. The band of any preceding claim, wherein the elastomer has a tensile strength of at least 15 MpA.

14. The band of any preceding claim, wherein the elastomer has a tensile strength in the range of 18 to 20 MpA.

15. The band of any preceding claim, wherein the elastomer has an elasticity greater than 100%.

16. The band of any preceding claim, wherein the elastomer has an elasticity greater than 500%.

17. The band of any preceding claim, wherein the elastomer has a hardness of at least 50 Shore.

18. The band of any preceding claim, wherein the elastomer has a hardness in the range of 60 to 70 Shore.

19. The band of any preceding claim, wherein the elastomer comprises a blend of 50 to 70% rubber, 25 to 35% filler and 5 to 15% oil.

20. The band of any preceding claim, wherein the elastomer has comprises about 60% rubber, about 30% filler and about 10% oil.