GB1598627A - Deflated tyre annular support - Google Patents

Description

(54) DEFLATED TIRE ANNULAR SUPPORT (71) We, FORD MOTOR COMPANY LIMITED, of Eagle Way, Brentwood, Essex CM13 3BW, a British Company, 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:- This invention relates to supports for tubeless tires.

United States patent No. 2,040,645 issued May 12, 1936 to F. S. Dickinson for a Noncollapsible Tire contains the following statement: "The principal object of the invention is to provide a tire which is designed to be inflated and which in the event of deflation from punctures, blow-outs or for any other reason may still be used without injury to the tire itself or to the rim or felly upon which it is mounted." Although it may be questioned as to whether a blown-out tire can be subject to any greater injury, it is highly desirable that some form of support be provided for preventing complete collapse of the tire in the event of deflation or overloading, or a combination or both. Numerous such supports have been proposed. Representative of the current state of the art is U.S. patent No.

3,949,796 issued April 13, 1976 to D. M.

Bartos of Dow Corning Corporation for a Safety Tire. The patent discloses what is described as an elastomeric safety insert for a pneumatic tire assembly. The insert is broadly described as having a toroidal configuration with protruberances extending therefrom to space the body portion of the insert from the rim and tire casing, permitting the insert to dynamically balance itself when the inflated tire rotates. When the tire is deflated the belt area between the tire shoulders is contacted and supported by the main body of the insert (see Fig. 3 of the patent).

U.S. patent 3,981,341 issued September 21, 1976 to J. R. Bauer and J. M. Forney of the Goodyear Tire and Rubber Company for a Safety Support for Pneumatic Tires. This patent broadly discloses a safety support mountable on a rim inside a tire chamber to support the shoulder areas and some of the belt surface located between the shoulders of the tire in a deflated condition.

The present invention provides a support for a tubeless tire comprising two axially spaced annular members composed of moulded elastomeric material for engaging opposite internal surfaces of the sidewalls of a tire, and support elements extending radially inwardly from the annular members retaining the annular members axially spaced from each other and, in use, engaging a wheel rim to space the annular members radially therefrom, each annular member being arranged to be compressed between a bight formed by a collapsed sidewall of the tire and being formed to provide increasing resistance to radial compression in the bight in an axial direction from its inner side to its outer side, whereby the compressive forces exerted by the bights urge the annular members away from each other.

In the preferred embodiment of the invention, the support includes twin annular members that are capable of being radially positioned intermediate the wheel rim and the tire tread portion when the tire is inflated, the members also having the capability of dynamically balancing themselves when the wheel is rotating. The members are constructed and arranged so that in tire deflated condition the annular members will seat themselves in the bight formed in each tire sidewall outwardly of the tire tread portion.

Each annular member is adapted to substantially limit the acuteness of the radius of curvature of the sidewall bight thereby relieving the stress in the tire cords and preventing opposed portions of each sidewall from rubbing against one another, This minimizes the consequences of a maximum reduction of the tire rolling radius that is attained with a completely flat tire. The consequences are such as friction heat, sidewall cord stress, differential gear fatigue and vehicle trim.

The invention also includes a road wheel assembly incorporating a support in accordance with the invention. In the preferred assembly of the invention, the tire is of the type having a tread portion, shoulder portions at the edges of the tread portion and outwardly curved sidewalls terminating in bead portions positioning the tire on the rim.

The annular members are supported on radially outwardly curved resilient support elements each having one end located in the annular well of the wheel rim and its other end situating each annular member radially intermediate the wheel rim and tire tread portion in axially continguous relation to a sidewall of the tire. Each annular member thus is positioned to seat within the bight formed in the contiguous sidewalls of the tire between related shoulder and bead portions of the tire upon deflation of the latter to limit radial movement of the tire shoulder portions toward the respective superposed wheel rim side edges when in a fully deflated condition.

Further features and advantages of the present invention will be made more apparent as this description proceeds, reference being had to the accompanying drawings, wherein: FIG. I is an elevational view of the annular support in accordance with a first embodiment of the present invention; FIG. 2 is a cross sectional view on 2-2 of FIG. 1 showing the wheel and tire assembly with the annular support assembly mounted therein; FIG. 3 is a cross sectional view showing the wheel, tire and annular support assembly of FIG. 2 in a deflated condition of the tire; FIG. 4 is a view in part similar to FIG. 2 showing a modification of the invention; FIG. 4a is a fragmentary side elevation of FIG. 4 looking in the direction of the arrows 4a-4a; and FIG. 5 is a view in part similar to FIG. 2 showing a further modification of the invention.

Referring now to the drawings, there is shown in FIGS. 1 to 3, inclusive, a preferred embodiment of the present invention as applied to a wheel and tire assembly. The tire shown comprises a conventional tubeless tire casing, generally designated 11, having a tire tread portion 12 in its perimeter, shoulder portions 13 at the edges of the tread portion 12 and outwardly curved sidewalls 14 extending toward the center of the wheel and terminating in wheel rim flange 15 engageable bead portions 16.

The wheel rim 17 shown is a conventional drop center rim having the side flanges 15 and a substantially axially centrally positioned annular well 18 for facilitating mounting of the tire casing 11.

As used herein the term "axially" refers to directions paralleling the axis of rotation of the vehicle wheel. Reference may also be made to directions extending "radially" of the axis of the wheel.

The annular support assembly, generally o designated 19, to be used with the tire and wheel, comprises a pair of axially spaced, symmetrical, annular members 21 and 22 adapted to be radially positioned intermediate the wheel rim 17 and the tire tread portion 12 when the tire casing 11 is inflated.

Each of the annular members 21 and 22 is supported in contiguous relationships to an inner wall surface 23 of a sidewall 14 of the tire casing on the outer perimeter 24 of resilient, radially outwardly extending support elements 25. Preferably, the support elements comprise a plurality of spokes 26 equally spaced from each other. As shown in Fig. 1, each annular member may be supported on at least three such spokes 26.

Preferably, each axially adjacent pair of spokes 26 are integrally molded to each other at 26a, see FIG. 2.

As shown in FIGS. 4 and 4a, the support assembly 19a may be molded as two symmetrically separate pieces 27 and 28 with the spokes 26 terminating in stepped end portions 29. The stepped end portions 29 are clamped between flanged plates 31 and 32 which are held in clamping position by rivets 33.

The annular members 21 and 22, as is the entire support assembly 19, are molded of an elastomeric material such as a self-skinned microcellular urethane having a density of 45 pounds per cubic foot and a surface hardness of approximately 75-85 Shore "A" as measured with a Durometer. The annular members 21 and 22 are molded in a generally quadrilateral shape, preferably in a trapezial shape. Each annular member has an axially outer generally radially extending and slightly convex side surface 34 facing an inner surface 23 of the tire casing sidewall 14 and an inner generally radially extending side surface 35 facing inwardly of the tire casing. As indicated above, the sides 34 and 35 are not necessarily parallel to each other.

Each annular member 21 and 22 has axially extending sides 36 and 37 which are inclined relative to one another so that the planar projections of the surfaces indicated by the lines 36a and 37a intersect radially outwardly of the surface 34 contiguous to the tire casing inner surface 23.

Each annular member 21 and 22 has an annular groove 38 extending axially outwardly from its inner surface 35 with the groove being of decreasing radial width toward the bottom 39 thereof.

The annular support assembly of the preferred embodiment is provided with an axial positioning or centering means comprising a flange 41 adapted to lie within the annular well 18 of the wheel rim 17. It will be understood that the annular support 19 may be molded with a flange 41 projecting laterally from both sides ofthejuncture 26a of the spokes. The flanges 41 then may be trimmed to fit within the rim well 18 to properly axially center the assembly within the inflated tire casing.

With respect to the annular support assembly 19a shown in FIG. 4, either clamping plate 31 or 32, or both, may be provided with a wide flange 42 as required to properly position or center the assembly on the wheel rim 17.

In operation, the annular support assembly 19 functions as follows: In FIG. 2 the tire casing 11 is shown as it appears in a normal inflated condition. The annular support assembly 19 is axially centered within the tire casing with the side surfaces 34 of the annular members 21 and 22 contiguous to the inner surfaces of the casing side walls 23. As the vehicle wheel rotates, the support assembly 19 floats on the wheel rim and dynamically balances itself since the spokes are resilient and present sufficient damping due to the inherent hysteresis of the chosen material.

Upon deflation of the tire casing or upon a flattening of the ground engaging portion of the tire casing due to an excessive load on the vehicle wheel, the cross section of the ground engaging portion of the tire casing appears substantially as shown in FIG. 3. Between each shoulder portion 13 and the corresponding wheel rim flange 15, each sidewall 14 of the tire casing forms a loop or bight which receives an annular member 21 or 22.

Each annular member is of sufficient radial thickness. that is, thickness between its sides 36-37, to substantially limit the acuteness of the radius of curvature of the loop or bight in a sidewall 14 thereby to relieve the stress in the tire casing cords and to prevent opposed bight portions of each side wall from rubbing against each other when the tire casing is run in a deflated condition.

Because of the aforementioned grooves 38 in the annular members 21 and 22, the resistance to radial compressibility of the annular members increases axially from the inside or central portion of the tire casing toward the sidewalls 14 or other portion of the tire casing. This is shown in FIGS. 2 and 3. In FIG. 2. the planar projection of the surfaces 36 and 37 of each annular member, as represented by the lines 36a and 37a, either intersect outwardly of the tire casing sidewall or are parallel to one another. When an annular member 21 or 22 is seated in the bight of the sidewall 14 of a deflated, partially deflated or overloaded tire, as shown in FIG. 3, the slope of each line 36a and 37a now extends inwardly as the sidewalls of the groove 38 pivot about the wall between the bottom 39 and the side surface 34. The greatest compression force on the annular member occurs between the shoulder 13 at the edge of the tire tread portion and the flange 15 of the wheel rim. As a result, the component of the forces acting on the annular members 21 and 22 urge the latter axially outwardly of the tire casing thereby limiting the radial collapse of the latter and prevent the annular members 21 and 22 from being urged inwardly.

As is well known in the tire annular support art, it may be desirable to provide a lubricant to reduce friction between the inner surfaces of the tire casing and the abutting sufaces of the annular members 21, 22 when the tire is operated in a deflated mode. As shown in FIG. 4, a plurality of lubricant capsules 43 may be positioned in the grooves 38. The entrance to each groove 38 may be provided with a retention nub or ridge 44 to hold the capsule in place until it is ruptured under the radial compression forces exerted by the tire casing.

The embodiment of the invention shown in FIG. 5 is similar to that shown in FIG. 2 except that the radially extending surfaces of the annular members 21 and 22 are provided with sawtooth serrations 45 and 46 directed to assure minimum resistance to movement axially outwardly of the tire casing into the bight of the sidewalls of a deflating tire. The serrations are effective to increase the resistance to withdrawal of the annular members 21-22 from the bight of the tire casing sidewalls in deflated condition of the tire casing.

There is a basic method for inserting the annular support assembly into the tire casing. This method is to insert an expansion turnbuckle diametrically across the assembly. The turnbuckle is then operated to elongate the assembly longitudinally of the turnbuckle thereby forcing the assembly into an oval or elliptical shape until the minor axis of the assembly is less than the diameter of the tire opening diametrically across the tire beads. The insert then is inserted into the tire until one major diameter end abuts the inner wall of the tire tread portion. It then will be found that the other major diameter end of the insert will drop into the tire opening. When the turnbuckle is removed to allow the assembly to return to a circular shape, the latter will be retained in the tire casing ready to be mounted with the tire on a wheel in a conventional manner.

WHAT WE CLAIM IS: 1. A support for a tubeless tire comprising two axially spaced annular members composed of moulded elastomeric material for engaging opposite internal surfaces of the sidewalls of a tire, and support elements extending radially inwardly from the annular members retaining the annular members axially spaced from each other and in use engaging a wheel rim to space the annular members radially therefrom, each annular member being arranged to be compressed

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

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. to fit within the rim well 18 to properly axially center the assembly within the inflated tire casing. With respect to the annular support assembly 19a shown in FIG. 4, either clamping plate 31 or 32, or both, may be provided with a wide flange 42 as required to properly position or center the assembly on the wheel rim 17. In operation, the annular support assembly 19 functions as follows: In FIG. 2 the tire casing 11 is shown as it appears in a normal inflated condition. The annular support assembly 19 is axially centered within the tire casing with the side surfaces 34 of the annular members 21 and 22 contiguous to the inner surfaces of the casing side walls 23. As the vehicle wheel rotates, the support assembly 19 floats on the wheel rim and dynamically balances itself since the spokes are resilient and present sufficient damping due to the inherent hysteresis of the chosen material. Upon deflation of the tire casing or upon a flattening of the ground engaging portion of the tire casing due to an excessive load on the vehicle wheel, the cross section of the ground engaging portion of the tire casing appears substantially as shown in FIG. 3. Between each shoulder portion 13 and the corresponding wheel rim flange 15, each sidewall 14 of the tire casing forms a loop or bight which receives an annular member 21 or 22. Each annular member is of sufficient radial thickness. that is, thickness between its sides 36-37, to substantially limit the acuteness of the radius of curvature of the loop or bight in a sidewall 14 thereby to relieve the stress in the tire casing cords and to prevent opposed bight portions of each side wall from rubbing against each other when the tire casing is run in a deflated condition. Because of the aforementioned grooves 38 in the annular members 21 and 22, the resistance to radial compressibility of the annular members increases axially from the inside or central portion of the tire casing toward the sidewalls 14 or other portion of the tire casing. This is shown in FIGS. 2 and 3. In FIG. 2. the planar projection of the surfaces 36 and 37 of each annular member, as represented by the lines 36a and 37a, either intersect outwardly of the tire casing sidewall or are parallel to one another. When an annular member 21 or 22 is seated in the bight of the sidewall 14 of a deflated, partially deflated or overloaded tire, as shown in FIG. 3, the slope of each line 36a and 37a now extends inwardly as the sidewalls of the groove 38 pivot about the wall between the bottom 39 and the side surface 34. The greatest compression force on the annular member occurs between the shoulder 13 at the edge of the tire tread portion and the flange 15 of the wheel rim. As a result, the component of the forces acting on the annular members 21 and 22 urge the latter axially outwardly of the tire casing thereby limiting the radial collapse of the latter and prevent the annular members 21 and 22 from being urged inwardly. As is well known in the tire annular support art, it may be desirable to provide a lubricant to reduce friction between the inner surfaces of the tire casing and the abutting sufaces of the annular members 21, 22 when the tire is operated in a deflated mode. As shown in FIG. 4, a plurality of lubricant capsules 43 may be positioned in the grooves 38. The entrance to each groove 38 may be provided with a retention nub or ridge 44 to hold the capsule in place until it is ruptured under the radial compression forces exerted by the tire casing. The embodiment of the invention shown in FIG. 5 is similar to that shown in FIG. 2 except that the radially extending surfaces of the annular members 21 and 22 are provided with sawtooth serrations 45 and 46 directed to assure minimum resistance to movement axially outwardly of the tire casing into the bight of the sidewalls of a deflating tire. The serrations are effective to increase the resistance to withdrawal of the annular members 21-22 from the bight of the tire casing sidewalls in deflated condition of the tire casing. There is a basic method for inserting the annular support assembly into the tire casing. This method is to insert an expansion turnbuckle diametrically across the assembly. The turnbuckle is then operated to elongate the assembly longitudinally of the turnbuckle thereby forcing the assembly into an oval or elliptical shape until the minor axis of the assembly is less than the diameter of the tire opening diametrically across the tire beads. The insert then is inserted into the tire until one major diameter end abuts the inner wall of the tire tread portion. It then will be found that the other major diameter end of the insert will drop into the tire opening. When the turnbuckle is removed to allow the assembly to return to a circular shape, the latter will be retained in the tire casing ready to be mounted with the tire on a wheel in a conventional manner. WHAT WE CLAIM IS:

1. A support for a tubeless tire comprising two axially spaced annular members composed of moulded elastomeric material for engaging opposite internal surfaces of the sidewalls of a tire, and support elements extending radially inwardly from the annular members retaining the annular members axially spaced from each other and in use engaging a wheel rim to space the annular members radially therefrom, each annular member being arranged to be compressed

between a bight formed by a collapsed side wall of the tire and formed to provide increasing resistance to radial compression in the bight in an axial direction from its inner side toward its outer side, whereby the compressive forces exerted by the bights urge the annular members away from each other.

2. A support according to Claim 1, in which: the annular members each has an axially outer generally radially extending side surface and an axially inner generally radially extending side surface, and a groove extending axially outwardly from its inner side surface the groove decreasing in radial width toward the bottom thereof to accommodate the radial compression of the annular member.

3. A support according to Claim 2, in which: the axially extending sides of each annular member are inclined relative to one another so that the planar projections of the axial sides intersect outwardly of the axially outer radial surface when the annular member is uncompressed and inwardly of the outer radial surface when radially compressed.

4. A support according to any one of claims 1 to 3 in which: the support elements comprise a plurality of resilient equally spaced spokes.

5. A support according to Claim 4, in which: the spokes supporting one annular member are each integrally molded to a spoke supporting the other annular member adjacent the wheel rim.

6. A support according to Claim 4 in which: the spokes supporting one annular member are joined, by clamping means, to the spokes supporting the other annular member adjacent the wheel rim.

7. A support according to Claim 6, in which: the clamping means is adapted to engage the wheel rim.

8. A support according to any one of claims 1 to 7 in which: each annular member is of generally trapezoidal cross section.

9. A support for a tubeless tire substantially as hereinbefore described and as illustrated in Figures 1 to 3, or Figure 4 or Figure 5 of the drawings.

10. A road wheel assembly comprising a wheel, a tubeless tire casing mounted on the wheel, and a support according to any one of claims 1 to 8 mounted on the wheel within the tire casing with the support elements engaging the wheel rim and the annular members lying in contact with the inner sidewalls of the tire casing.