Device for motor vehicle running flat and method for mounting

Resilient tires and wheels – Tires – resilient – Wheel securing means

Reexamination Certificate

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Details

C152S400000, C152S520000

Reexamination Certificate

active

06286574

ABSTRACT:

The invention relates to a motor vehicle run-flat device enabling a considerable distance to be traveled (at least 100 km) at a relatively high speed (not less than 80 km/h) with a tire that is partially or completely deflated. The invention also relates to a method of fitting the device.
BACKGROUND OF THE INVENTION
Known devices of this type can be of relatively simple structure when they are designed for use with rims that can be disassembled or with special rims, however when they are to be fitted on standard rims (made as a single piece) having fixed lateral flanges for holding the beads of a tire, such devices are necessarily made of a plurality of parts each in the form of an arc of a circle, which parts are connected together end to end by mechanical link means using screws, eccentric means, etc. . . . so as to form a running ring which can be clamped onto the rim and which can be dismantled and withdrawn from the rim in spite of its lateral flanges.
These linking and clamping means are the source of considerable drawbacks since handling them is awkward and sometimes lengthy (it is necessary to place the hands and/or tools between the rim and the tire), yet such handling can be critical since poor clamping of the running ring on the rim can cause it to be destroyed quickly when running on a flat tire. Furthermore, the link means are sensitive to shock and are subjected in use to considerable forces which vary over time, thereby giving rise to fatigue phenomena that can cause them to break quite quickly, thereby destroying the run-flat device.
For fitting to mass-produced vehicles, run-flat devices must be capable of being fitted on standard wheel rims, i.e. on rims that are made as a single piece with lateral flanges.
For this purpose, devices have already been proposed that are formed by at least two circularly-arcuate elements which are connected end to end by link means, e.g. using screws, eccentrics, etc., in order to form a continuous ring which is clamped onto the rim and which can be fitted to and stripped from the rim in spite of its lateral flanges.
It has been found that such link means are often the cause of run-flat devices being destroyed prematurely for various reasons (poor clamping, sensitivity to shock, to vibration, fatigue phenomena, etc. . . . ).
OBJECTS AND SUMMARY OF THE INVENTION
A particular object of the present invention is to avoid those drawbacks.
Another object of the present invention is to provide a run-flat device of the above-specified type which is easy to fit on a standard rim without requiring special tooling.
Another object of the invention is to provide a run-flat device of the above-specified type which is easier to manufacture and assemble than are known devices of the prior art and which is more reliable.
Another object of the invention is to provide a device of this type whose performance can be guaranteed in spite of relatively slack manufacturing tolerances.
Another object of the invention is to provide a method of fitting such a device which is simpler and easier to implement.
The invention seeks to provide a motor vehicle run-flat device that can be used on a standard rim having lateral flanges for holding the beads of a tire, the device nevertheless being of a structure that is much simpler, that provides much higher performance, and that is much more reliable than known devices of the prior art.
Another object of the invention is to provide a device of this type which is easier and quicker to fit than are devices of the prior art.
To this end, the invention provides a motor vehicle run-flat device designed to be fitted so that it is clamped on a standard wheel rim having lateral flanges for holding the beads of a tire, wherein the device is constituted by at least two coaxial annular pieces engaged one on the other, the radially-inner first annular piece being of a relatively rigid material and forming an open ring around the rim, and the radially-outer second annular piece being based on an elastically deformable material and comprising a continuous one-piece ring surrounding the first piece and having an inside diameter substantially equal to or greater than the outside diameter of a lateral flange of the rim.
The device of the invention thus has the essential advantage of being completely free of any of the above-mentioned link or clamping means as used in the prior art while nevertheless being suitable for fitting on standard rims having fixed lateral flanges, with the device being assembled by engaging a continuous outer ring on an open inner ring.
The simplicity of the structure and the reliability of the device of the invention are considerably greater than those of known prior devices.
According to other characteristics of the invention, the second annular piece has an inside diameter that is slightly smaller than the outside diameter of the first piece and it is engaged by force thereon, thus ensuring that the first piece is clamped against the rim.
Advantageously, the second piece includes annular means that are substantially inextensible, e.g. embedded in the material constituting said second piece, such that when the second piece is engaged on the first, the material of said second piece is compressed between the first piece and the inextensible annular means of the second piece, thereby clamping the first piece strongly against the rim.
According to yet another characteristic of the invention, the contact surfaces between the first and second pieces are frustoconical, at least in part.
This makes it easier to center and fit the second piece on the first, and also ensures that the second piece is automatically locked on the first when running on a flat tire (providing the frustoconical surfaces flare from the outside towards the inside of the tires), since the forces which act on said pieces when running on a flat tire act from the outside towards the inside of the tires.
Finally, the device is also characterized by axial holding means for holding the second piece on the first.
Thus, once the second piece has been fitted and engaged by force on the first, it is held positively thereon, thus avoiding any risk of the two pieces accidentally separating in use.
In a first embodiment of the invention, the axial holding means can be annular grooves and ribs or the like which are formed at the interface between the first piece and the second piece.
In another embodiment, the axial holding means comprise a wedge-forming annular element between the first and second pieces, which element is held in position against these two pieces by fixing or locking means.
In another embodiment of the invention, the device includes an intermediate annular piece of relatively rigid material which forms an open ring and which is interposed between the first and second annular pieces.
This makes it possible in particular to reduce the radial thicknesses of the first piece and of the intermediate annular piece which are both made of relatively rigid material, thus making it easier to fit them on the rim.
The contact surfaces between the first piece and the intermediate piece are preferably frustoconical, at least in part, and axial holding means are provided for holding the intermediate piece on the first piece, for example annular grooves and ribs or the like formed at the interface between the first piece and the intermediate piece.
In general, the device of the invention is particularly designed for use on the wheels of private vehicles, but it can also be used on the wheels of larger vehicles, and it turns out to be particularly effective, with tests having shown that it is possible to run on a flat tire with this device even under driving conditions that are extreme.
In addition, the device is extremely insensitive to shock.
The invention also provides a method of fitting a run-flat device on a motor vehicle wheel, the device comprising at least:
a radially-inner annular piece and an intermediate annular piece both of relatively rigid material and open at at least one point in their respective peripheries, and designed to be fitted

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