GB1571916A

GB1571916A - Vehicle wheel assembly

Info

Publication number: GB1571916A
Application number: GB721/77A
Authority: GB
Original assignee: Uniroyal GmbH
Current assignee: Uniroyal GmbH
Priority date: 1976-01-09
Filing date: 1977-01-10
Publication date: 1980-07-23
Also published as: NO770057L; SE7700175L; BE850193A; LU76540A1; JPS5286604A; CA1056284A; NL7700194A; TR19520A; AU2115177A; DK7477A; FR2337633A1; DE2600691A1

Description

(54) VEHICLE WHEEL ASSEMBLY (71) We, UNIROYAL GMBH (formerly known as UNIROYAL AG), a corporation organized under the laws of the District Court of Aachen, West Germany, located at D-51 Aachen, Huettenstrasse 7, West Germany, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to a vehicle wheel assembly comprising a drop-center wheel rim having flanges, a tubeless pneumatic tire mounted on the rim and having bead regions which, owing to the pressure within the tire are forced against bead seats on the rim, and a safety insert in the form of an inflated annular hollow body positioned in the drop center of the rim and bearing axially outwardly on the bead regions of the tire in order to hold these in contact with the bead seats.

Assemblies of this nature are known, the objective being that in the event of puncture of the tire the safety insert will hold the beads in position on the rims, so that control of the vehicle can be maintained and the vehicle can continue to travel safely for significant distances.

According to the present invention in an assembly as aforesaid the hollow body is itself puncture-resistant, the radially outermost portion of the radially outer surface of the hollow body lies at a location which is radially outwardly spaced from the radially outermost parts of the rim flanges by a distance less than one quarter of the radial distance between the radially outermost parts of the rim flanges and the interior of the normally inflated tire at the mid-circumferential plane thereof, the thickness of the wall of the hollow body is greatest in a radially outward area thereof and decreases into sidewall regions of the hollow body and the radially outer surface of the hollow body is formed from an anti-friction rubber compound (as herein defined).

The term "anti-friction rubber compound" is used herein to mean a compound of a rubber and an additive which reduces the resistance to friction of the rubber (for example rubber compounded with silicone oil or with wax) or an elastimer having a low coefficient of friction (for example silicone rubber or a polytetrafluoroethylene composition).

In an assembly according to the invention, the inflated hollow body bears in its operating state adjoining the wheel flanges a substantial portion of the load if the tire has been flattened as a result of tire failure such as a puncture. The load transfer in the area of the wheel rim flanges becomes thus substantially reduced and, as a result, the marked friction in this area in the course of travel with a flattened tire is likewise reduced substantially. In the flattened state, the friction in the area of the inflated hollow body is additionally substantially reduced during the absorption of the load by the anti-friction rubber compound. Moreover, the inflated hollow body itself is designed to be puncture-resistant so assisting the security of the assembly. This object can be achieved in a variety of ways.

Accordingly, the inflated hollow body may have its radially outer wall reinforced by a belt consisting of at least two plies of thin steel cord. The cords in said plies can be arranged at identical or different angles, running however in opposite directions. The belt edges desirably extend down into the area of the drop-center rim, thereby protecting the hollow body against the penetration by outside elements into any sensitive surface areas.

Another possibility for rendering the hollow body puncture-resistant is to provide it with a puncture sealant substance, whether a semi-plastic puncture sealant layer or a loose particulate sealant, or to inflate the hollow body by filling it with a foam or solid filling per se known in the tire art as a protection against penetrating foreign bodies. By using a sealant or a protective filling (foam or solid), one avoids that, upon penetration of pointed objects into the hollow body, the hollow body becomes damaged to such an extent that it loses its support function in the case of a tire failure.

Contrary to the many proposals to fill a tire completely with foam, an assembly as aforesaid offers the advantage that, in the course of normal travel and in the normal operating state of the tire, the hollow body is in contact with the tire only in the area of the bead regions and does therefore not exert any effect on the behavior of the tire during travel. Moreover, as a result of the limiting of the foam or solid filling and of the hollow body to a relatively small radial area one guarantees against the occurrence of any substantial level of imbalance.

Rather, the hollow body is firmly and immovably seated on the rim and is capable of contributing significantly and frequently decisively in the event of a tire failure to permit the vehicle to continue travelling at moderate speed with good controllability.

Another possibility for designing the hollow body to be puncture-resistant resides in that one applies at a suitable point of the hollow body a layer of material having a self-sealing effect. Particularly suitable for this purpose is a layer comprising a semiplastic material based on a cured or partially cured elastomer in combination with a permanently plastic or tacky material. Such a material is capable of reliably closing a perforation produced through a puncture of the hollow body.

Another possibility for achieving self-sealing of the hollow body resides in that small plug-like elements made of natural or synthetic rubber are present in the free inside space of the body. As a result of suction created by escaping air, one or the other of the particles comes to be carried along and is capable of providing a hermetic seal of the resultant perforation (see, for example, U.S. patent 3,042,098, Reinowski et al., July 3, 1962).

The invention is explained in greater detail by means of schematic drawings relating to exemplified embodiments in which: Fig. 1 represents a cross-section through a vehicle wheel assembly according to a first embodiment of the invention, illustrating a tire in a partially flattened state; and Fig. 2 represents, on a larger scale, a cross-section of a second embodiment of assembly according to the invention.

The pneumatic tire 1 illustrated in Fig. 1 has a tread 2 and sidewalls 3 terminating in beads 4 and 5 maintained on seats adjoining the rim flanges of a drop-center wheel rim 6.

It is assumed that the tire has been damaged by a foreign body and, in its condition illustrated in the drawing, has already lost a substantial portion of its inflation air.

Upon further escape of air, the tire applies with its inside surface under load onto the areas of the sidewalls adjoining the beads 4 and 5 so that the tire comes to be substantially braced on the wheel flanges. Upon continued travel there would occur, in the absence of the invention, as a result of the attendant squeezing and compressing, a substantial friction between the tire portions lying on one another and, as a result, a premature destruction that would rapidly call an end to any continued travel of the vehicle even at moderate speeds.

The controllability of a vehicle travelling with flattened tires is preserved sufficiently as long as the firm connection between the tire and the rim can be preserved, that is to say, as long as the beads 4 and 5 retain their position on the rim even in the case of a flattened tire.

To achieve this object there is provided an inflated hollow body 7 which, in its operating condition as illustrated in Fig. 1, has an axial width somewhat greater than the width of the drop-centre wheel rim and protruding radially outwardly out of the bed of the rim by a predetermined value above the wheel flanges. It will be noted that the inflated hollow body projects radially outwardly above the radially outer part of the rim flanges by only a minor amount of the total radial distance between the radially outer part of the rim flanges and the interior of the normally inflated tire at the mid-cir cumferential plane thereof; that minor amount must be less than a quarter and is preferably not more than about one or two tenths of that total radial distance. Furthermore the hollow body takes up only a very minor fraction {usually less than 25%) of the total available volume within the normally inflated tire.

The inflated hollow body consists of an elastimer material 8 that is cured and into which there is embedded a tire cord ply 9 defining the dimension of the cross-section of the hollow body in its inflated state. By proper construction, the outside diameter of the inflated hollow body 7 is by that much greater than the rim flange diameter that, in the event of a tire failure, the hollow body can assume a portion of the load. In the absence of this arrangement, the lower por tion of the tread 2 of the tire shown in Fig.

1 would, in the event of continued decrease of the inflation pressure, come to be braced against the tire segments at the elevation of the dash-and-dot line 13, which are supported in turn by the wheel flanges. Instead the tread section 2 attains in the event of a flattening of the tire a load-bracening support from the moment the interior of the tread section has attained the dash-and-dot line 12. In the process, the tire bears centrally onto the inflated hollow body that is therefore capable of absorbing a substantial portion of the load and of substantially reducing the the transfer of load in the area of the wheel flanges.

In order to reduce friction occurring upon the mutual contacting of tire components under load and during travel, the hollow body elastomer mass 8 itself or else a special outer ply of the hollow body consists of an anti-friction rubber compound guaranteeing favourable sliding under certain conditions.

A material that has proved to be particularly suitable for this purpose is rubber containing silicone oil. However, rubbers containing wax or other substances are likewise suited for this purpose.

Preferably, one covers not the entire hollow body, rather, one applies a special layer 10 made for instance of silicone oil-containing rubber so as to cover completely only the exposed area of the hollow body.

In the event of tire puncture or failure, this layer guarantees that a lubrication becomes effective between the superpositioned layers of rubber, which reduces substantially friction and generation of heat and, consequently, prevents to a large extent premature tire destruction during travel on a punctured tire.

The rubber into which a lubricating substance is compounded to provide the desired anti-friction properties may be any suitable conventional rubber normally used in the construction of tires, whether natural rubber or a synthetic rubber (e.g., SBR, NBR, polychloroprene, or other elastomer based on conjugated diene [e.g., butadiene, isoprene] homopolymers or copolymers [e.g., copolymers with copolymerizable monoethylenically unsaturated monomers such as styrene, acrylonitrile, vinylpyridine], as well as rubbers with little or no unsaturation such as ethylene-propylene copolymer, ethylenepropylene-non-conjugated diene terpolymers ["EPDM"], polyurethane elastomers and thermoplastic rubbers. Any suitable known lubricating or anti-friction substance may be compounded into the elastomer in amount sufficient to provide the desired low friction properties. As indicated, silicone oil is a preferred anti-friction additive for the rubber but other lubricating substances can also be used such as waxes (animal, vegetable, mineral or synthetic wax), various softeners or plasticizers (e.g. high boiling phthalate, adipate or sebacate esters of such alcohols as octyl alcohol and cyclohexanol), or lubricants such as erucyl amide, oleyl amide, sodium stearate, aluminum stearate, oleyl palmitamide, stearyl eurcamide, oleamide and ethylene bis stearamide. More than one such anti-friction additive may be incorporated in the rubber compound if desired.

Instead of employing a rubber into which an anti-friction substance is compounded prior to vulcanization, one may employ, as the special layer 10 (or as the inflatable body 7 in the event that the special layer 10 is omitted), an elastomer which is in itself inherently anti-friction, for example silicone rubber curable to an elastmeric state, or a polytetrafluoroethylene composition.

An example of an anti-friction rubber stock containing silicone oil is (by weight): 50 parts natural rubber smoked sheet, 50 parts cis-polybutadiene rubber, 45 parts furnace carbon black, 4 parts process oil (petroleum hydrocarbon oil or aromatic type), 5-15 parts dimethyl silicone oil (viscosity 60,000 cp), 5 parts tackifier (hydrogenated rosin), 2 parts paraffin wax, 2.5 parts antioxidant (acetone-diphenylamine condensation product), 4 parts zinc oxide, 1.5 parts stearic acid, 0.8 part accelerator (tetramethyl thiuram disulfied) and 2.1 parts sulfur.

The assembly can most reliably perform its duty, as the hollow body is itself puncture-resistant even in those instances in which a foreign body in the damaged tire comes in direct contact with the hollow body after flattening of the tire.

In the case of the example according to Fig. 1, this object is achieved in that, following the introduction of the hollow body into the drop-center rim, the hollow body is inflated by being filled with a foam 11 (e.g., polyurethane elastomer foam) so as to attain the desired shape and cross-sectional dimension, with said foam guaranteeing, even in the event of penetration of the hollow body by a pointed element, that the hollow body substantially retains its supporting function.

In the normal state of operation of the tire, neither the foam filling nor the hollow body 7 as a whole (which is in contact with the tire in the area of the bead regions only and which, having small radial dimensions, is firmly embedded in the drop-center rim) can impair the travel properties of the tire.

Alternatively, in place of a foam filling, suitable solid filling may be used (see, for example, U.S. patent 3,866,651, Gomberg, Feb.

18, 1975) to prevent collapse of the hollow body even if punctured.

In the case of the exemplified embodiment according to Fig. 2, the inflated tube-shaped hollow body 24 is fitted into the drop-center wheel rim 23 in the identical manner as in the case of the exemplified embodiment according to Fig. 1, with the hollow body reliably supporting and securing the beads 21 and 22 of the tire 20 in the condition shown in the drawing.

Likewise in this case, the hollow body 24 can consist of a cured elastomer material 25 designed, if indicated, to have its shape retained by means of a tire cord. The hollow body is reliably protected against damage by foreign bodies or the like by means of a belt 26 preferably consisting of at least two thin plies 27, 28 of steel cords, the cords in different plies being arranged at identical or different angles but cords in adjacent plies always being oriented in opposite directions. As a result, the belt forms a dense net of steel on the exposed areas of the hollow body, with the steel netting reliably preventing a piercing of the hollow body by foreign elements. For this purpose, the belt 26 extends with its edges preferably down into the drop-center rim, an area in which the inflated hollow body is reliably protected by the rim itself.

Likewise in the case of this exemplified embodiment, the hollow body itself can be made of an elastomer composition containing a silicone oil, wax, or similar substances as described above. Preferably, however, there is provided a special ply made for instance of such rubber composition and designated by the reference 29.

It is of course understood that, even in the case of the embodiment according to Fig. 2, the inflated hollow body can be provided with a foam filling similar to the foam filling 11 of the exemplified embodiment according to Fig. 1, or with a solid filling, in order to reinforce even further the unimpairability of the hollow body under all circumstances.

Even though it is known that silicone oil containing rubber compounds or rubber compounds exuding for instance wax do have a friction-reducing effect, this arrangement plays a special part by guaranteeing not only against a premature destruction of the tire itself but, above all else, assuring also the maintenance of the operating capacity of hollow body. The moment the tire has assumed a sufficiently flat state following a tire failure, the anti-friction rubber compound enters into action under the effect of the compression of the surface pressure and the increased temperature caused by friction so that, as in the case of an elastic bearing, a rolling motion under load becomes possible.

A further possibility for designing the hollow body to be itself puncture-resistant resides in providing the hollow body with a self-sealing means, notably a layer made of a self-sealing substance. Said layer can be arranged at any suitable site of the hollow body for instance on its inside or else within the thickness of the hollow body. Any suitable conventional self-sealant or puncturesealant for pneumatic tires or inner tubes may be used for this purpose, such as for example those disclosed in U.S. patents 2,782,829, Peterson et al., Feb. 26, 1957; 2,802,505, Peterson et al., Aug. 13, 1957; 2,811,190, Iknayan et al., Oct. 29, 1957; 3,903,947, Emerson, Sept. 9, 1975; 3,935,893, Strang et al., Feb. 3, 1976; 3,952,787, Okado et al., Apr. 27, 1976; or 3,981,342, Farber et al., Sept. 21, 1976. As is well known, such sealant compositions are usually semi-plastic materials, frequently based on a cured or partially cured elastomeric component in combination with a permanently plastic or tacky component. Alternatively, a free particulate solid type of sealant may be used, as in U.S. patent 3,042,098 referred to previously.

In this case, one can preferably use partially vulcanized elastomers, in particular rubber compounds available in their tacky, plastic state.

Self-sealing tire failure sealing materials such as, for instance, depolymerized natural rubber or high-molecular rubbers or unsaturated elastimers containing titanium ester and that are partially vulcanizable can likewise be used (see U.S. patent 3,981,342, referred to above).

Moreover, mixtures made up of butyl rubber and polychloroprene or else neoprene or mixtures made up of polyisobutylene and chloroprene or neoprene are suitable for this purpose.

The various forms of manufacturing a tubelike body having included a belt reinforcement are well known to those skilled in the art. For example, a tubelike body, i.e.

which consists of a silicone oil containing rubber stock wall, may be built up on a mandrel. An inner liner tape may be wound up on the mandrel in order to have an overlapped bandage. Thereon applied is a puncture sealant layer and thereupon applied is a cross angled, thin, steel cord double ply belt reinforcement. Then a silicone oil compounded rubber tape may be wound up to a helical lined tube covering all the other elements and forms an endless body. This green tube with a valve may then be vulcanized in a mold to produce a hollow body as described above.

Preferably, it is appropriate to use separate valves for inflating the main chamber of the tire and the hollow body. The preferred mounting of the body onto the rim is: first, one of the beads of the tire is put on the rim; second, the hollow body is stripped over the free rim flange to put it into the rim; and third, the other bead of the tire is put on the rim.

Use of assemblies according to the invention helps to achieve that a vehicle can, in the case of tire puncture or failure, reach at moderate speed a repair shop or service station that is still miles away.

In the embedded reinforcing ply 9, the cord angles described in U.S. patent 3,242,964, Mosshart et al., March 29, 1966, may be employed.

WHAT WE CLAIM IS: 1. A vehicle wheel assembly comprising a drop-center wheel rim having flanges; a tubeless pneumatic tire mounted on the rim and having bead regions which, owing to the pressure within the tire, are forced against bead seats on the rim; and a puncture-resistant inflated annular hollow body positioned in the drop-center of the rim and bearing axially outwardly on the bead regions of the tire in order to hold these in contact with the respective bead seats, the radially outermost portion of the radially outer surface of the hollow body lying at a location which is radially outwardly spaced from the radially outermost parts of the rim flanges by a distance less than one quarter of the radial distance between the radially outermost parts of the rim flanges and the interior of the normally inflated tire at the mid-circumferential plane thereof, the thickness of the wall of the hollow body being greatest in a radially outward area thereof and decreasing into sidewall regions of the hollow body and the radially outer surface of the hollow body being formed from an anti-friction rubber compound (as herein defined).

2. A vehicle wheel assembly according to claim 1 in which the inflated hollow body has an axial extent no less than the width of the drop-center of the rim.

3. A vehicle wheel assembly according to claim 1 in which the whole of the wall of the hollow body comprises an anti-friction rubber compound (as herein defined).

4. A vehicle wheel assembly according to claim 1 or claim 2 in which the radially outer surface of the hollow body is formed by a cover layer of an anti-friction rubber compound (as herein defined).

5. A veheicle wheel assembly according to any one of the preceding claims in which the thicker wall section is formed by incorporation of an additional ply of material into the radially outward area of the hollow body.

6. A vehicle wheel assembly according to any one of claim 1 to 4 in which the thicker wall section is formed by a cover layer over the radially outward area of the hollow body.

7. A vehicle wheel assembly according to any one of the preceding claims, in which the hollow body is inflated by being filled with foam.

8. A vehicle wheel assembly according to anyone of the preceding claims in which the inflated hollow body is reinforced with tire cord material.

9. A vehicle wheel assembly according to any one of the preceding claims in which the hollow body has its radially outer wall reinforced by a belt consisting of at least two plies of thin steel cord.

10. A vehicle wheel assembly according to claim 9 in which the belt edges extend down into the area of the drop-center rim.

11. A vehicle wheel assembly according to any one of the preceding claims in which the hollow body incorporates a layer made of self-sealing material.

12. A vehicle wheel assembly according to any one of claims 1 to 10 in which particulate puncture sealant material is present inside the hollow body.

13. A vehicle wheel assembly according to any one of the preceding claims in which a small number of free plug-like small elements made of natural or synthetic rubber are present in the free inside space of the hollow body.

14. A vehicle wheel assembly substantially as herein described with reference to either Figure of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. cord angles described in U.S. patent 3,242,964, Mosshart et al., March 29, 1966, may be employed. WHAT WE CLAIM IS:

1. A vehicle wheel assembly comprising a drop-center wheel rim having flanges; a tubeless pneumatic tire mounted on the rim and having bead regions which, owing to the pressure within the tire, are forced against bead seats on the rim; and a puncture-resistant inflated annular hollow body positioned in the drop-center of the rim and bearing axially outwardly on the bead regions of the tire in order to hold these in contact with the respective bead seats, the radially outermost portion of the radially outer surface of the hollow body lying at a location which is radially outwardly spaced from the radially outermost parts of the rim flanges by a distance less than one quarter of the radial distance between the radially outermost parts of the rim flanges and the interior of the normally inflated tire at the mid-circumferential plane thereof, the thickness of the wall of the hollow body being greatest in a radially outward area thereof and decreasing into sidewall regions of the hollow body and the radially outer surface of the hollow body being formed from an anti-friction rubber compound (as herein defined).