GB2167359A - Inserts for supporting deflated tyres - Google Patents

Abstract

A run-flat insert for a pneumatic tyre incorporates an exterior surface heat insulation and anti-friction skin 32. <IMAGE>

Description

SPECIFICATION Run-flat tyre inserts The invention relates to inserts for tyres on motor vehicle wheels that enable the effects of a puncture or other deflation to be overcome.

Basically, tyre inserts hereof comprise closed-cell elastomeric material that, in normally inflated tyres, are substantially free of contact with the interior tyre wall, but, in a punctured or otherwise deflated tyre, offers sufficient immediate support to the tyre side walls to prevent ruinous buckling thereof and, subsequently, after being worked by repeated compression/expansion, expands substantially to fill the tyre cavity and support the tyre for a period of "get home" running pending repairs. Extensive tests have demonstrated the efficiency of such supports, particularly in the form of separable strips installed as rings side-by-side within the tyre on the outer periphery of the wheel, to such extend as readily to afford some tens, even hundreds, of miles of near normal running pending repair.

Using one particular grade and tyre of sorbo (type number ES7068) for such insert. rings, it has proved to be feasible, for all tyres encountered to date, to achieve the multiple objectives of avoiding insert material working at normal tyre inflation, supporting tyre walls at first-deflation sufficiently to avoid permanent damage from buckling of the walls, and expansion to fill the tyre and afford running pressure, all without damaging increase of tyre wall temperature, often virtually no or very little increase of that temperature and without damaging increase of interior insert material temperatures leading to early disintegration thereof.

Howver, being concious of the fact that other closed-cell elastomeric materials must be available and/or capable of development that are or would be satisfactory save for higher temperatures and/or greater susceptibility to chafing wear, it is now proposed herein that some exterior surface coating, skinning or special treatment be applied that has heat insulating and/or antifriction properties.

It is envisaged that such application be at least at outer corners of outermost insert rings, if not entirely to their outer sides and/or outer periphery, even further to their inner sides and to the sides and/or peripheries even of any intermediate insert rings.

Another proposal hereof concerns the formation within the combined insert material of cavities or voids, so as to reduce the bulk of such material used and/or achieve a preferred boundary-enclosed volume there of for a given desired or required bulk of material.

This proposal has application both to materials other than the aforementioned sorbo and also to the use of that material itself.

Broadly, then, knowledge of the expansion characteristics, and the expanded properties, of any particular material enables minimising material usage and/or optimising initial tyre wall support and ultimate running pressure properties.

Moulded insert rings can have such cavities or voids formed in a variety of ways, including the obvious one of making depressions or indents in one side face, or both side faces. It stock strip material for the insert rings is formed by extrusion, such indenting could be by way of grooves, and further cavities or voids could optionally, intentionally or inevitably be divided at notch-like cut-outs or similar to aid forming to a ring.

A further proposal hereof involves aiding fitment and/or flexing of insert rings as required at first-deflation by mutual hold means for inner and/or outer boundaries of adjacent insert rings, whether via formation, comb-like, by slotting or cutting the material only partially from one edge, or by retention tape or other bonded or otherwise secured material whether circumferentially or intermittently across their widths, or by wire, thread or cord whether as stitching or otherwise.

Moreover, basis production, storage and handling can thus be facilitated by production and/or supply in bulk-connected rings separable individually or in sets at fitment to a particularly tyre/wheel combination.

To avoid the possibility of inflation valves being even partially obstructed by insert rings, it is proposed that valve heads be formed with grooves as air channels and/or with facets or side faces for air exits.

Specific implementation of these proposals will now be describe, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a section through part of a wheel, an insert system and a tyre showing coating etc of insert parts; Figure 2 is a similar section showing incorporation of voids into a tyre insert system; Figure 3 shows a variant for the tyre inserts of Fig. 2; Figure 4 is a section showing insert rings connected at their bottoms; and Figure 5 shows specially configured valves.

In Fig. 1, vehicle wheel 10 has a well 12 and flanking shoulders 14, 16 to outer rims 18, 20 within which beads 22, 24 of a tubeless tyre 26 are retainingly seated, all in conventional manner.

Within the tyre cavity and seated on the wheel periphery is an insert system of the aforesaid closed-cell expansible material, the insert system actually shown comprising three side-by-side strips or rings 30A, 30B, 30C of such material. As shown, the t,o outer rins 30A, 30C are similarly configured, one being the mirror image of the other, and seat on the shoulders 14, 16, whereas the central ring 30B seats in the well 12.It is believed to be worth noting, at this stage, that it is viable for all rings to be identical, at least as to height and interior diameter if not also to basic shape and thickness (width), if the well 12 is filled to the level of the shoulders 14, 16 by a suitable material, with consequent advantages from stock sizes of inserts being then entirely a matter of nominal wheel size and tyre profile, rather than further depending on wheel well configuration, and can be made up from any desired number less than or greater than three.

Fig. 1 shows each of the insert strips or rings covered by a layer, coating, skin or the like 32 that has anti-friction and/or heat insulating properties for the purposes aforesaid. It will be appreciated that, at least for anti-friction and/or wear-resistance purposes, minimum such application, or suitable treatment, such as impregnation or toughening by heat or solvents or reaction agents, is at the outermost corners of the outer strips with optional extension over outer sides and/or tops thereof, and/or to top of the inner strip to a maximum short of adjacent confronting surfaces of the strips.

In Fig. 2, just two insert strips are shown and have their confronting surfaces indended at 34, so as to form voids also for purposes as aforesaid. It will be evident that the indentations can be grooves and/or non-registering, again as aforesaid.

Turning to Fig. 3, four insert strips are shown with varying height formation of their surfaces, whether, as normally intended, sufficiently deeply to create significant voids or, as may well be, just shallowly enough to reduce the possibility of strips sticking together (in which case they may more resembie dimpling or scoring in non-matching patterns).

In Fig. 4, a unitary insert is shown with slotting from its outer periphery effectively to form the aforementioned strips, but in a structure that is, perhaps, more readily machinefitted.

Additionally, say to promote outward bending of the outer strips, or alternatively, simply to facilitate handling, insert strips may be interconnected at their tops, say by intermittent stitching (dashed line 36) or by tape (dashed line 38).

Turning to Fig. 5, modified valves are shown with grooved heads 42 affording channels to inflation gas and/or side-exiting 44 from domed or faceted heads, so as to reduce risks that insert material hereof will effectively block them.

Lastly, we point to Fig. 6 showing a well insert 28 as alluded to above and with a possible smaller, multiwheel-fitting, outline shown at 28'.

If a suitable material is or becomes available for use in a single piece as a tyre insert, it is feasible to employ a doughnut shape that could use at least corners of the well of a wheel for location purposes at fitment.

Claims (7)

1. Pneumatic tyre inserts which incorporate an exteriof surface insulation and/or anti-friction skin.

2. Pneumatic tyre inserts in which cavities are formed so as to reduce material bulk for a desired boundery enclosed volume, and to facilitate bending and movement in a prefered manner.

3. Pneumatic tyre inserts which have their rings joined at their bases to aid fitment and preferred flexing as required on initial deflation.

4. Pneumatic tyre inserts which have their rins joined as hereinbefore described to enhance ease of production, storage, handling and preferred flexing.

5. Pneumatic tyre valves with heads grooved and faceted, or side facing for air exits to prevent obstruction by inserts.

6. A pneumatic tyre insert system which incorporates a well fitting strip to compensate for variation in wheel profile and accompanying insert rings.

7. Pneumatic tyre inserts substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings and any permutations of the same.