WO2018211194A1

WO2018211194A1 - Device for protecting a tyre sidewall

Info

Publication number: WO2018211194A1
Application number: PCT/FR2018/051068
Authority: WO
Inventors: Agnès DEGEORGES
Original assignee: Compagnie Generale Des Etablissements Michelin
Priority date: 2017-05-16
Filing date: 2018-04-27
Publication date: 2018-11-22
Also published as: FR3066436A1; FR3066436B1

Abstract

Tyre (1) comprising a crown portion (20) comprising a tread (21) and extended axially on each side by sidewalls (30), this tyre being provided with a device (10) for protecting at least one side wall against external attacks and comprising a plurality of raised elements (101, 102) in at least one first circumferential line (C1) and a second circumferential line (C2), the first circumferential line being the closest to the edges (210) of the tread of the tyre, each raised element in the one same circumferential line of suffix i having a maximum height Hi, measured with respect to the surface of the sidewall, the maximum heights Hi of the raised elements (101, 102) of the successive circumferential lines (C1, C2,), progressing from the first circumferential line towards the subsequent ones decreasing, this tyre being such that each raised element comprises an intermediate region of elongate shape in the circumferential direction, this intermediate region comprising two extensions that form a non-zero angle with the intermediate region.

Description

DEVICE FOR PROTECTING A TIRE SHEET.

FIELD OF THE INVENTION

The present invention relates to heavily loaded vehicle tires such as tires intended to equip heavy goods vehicles. It relates more particularly to a device for protecting these tires against attacks on the flanks of these tires.

STATE OF THE ART

[0002] In the usual way, a tire for a heavy vehicle comprises beads intended to come into contact with a rim, these beads being extended by flanks connecting on either side of a crown portion, the latter being covered by a tread whose function is to ensure contact during taxi with the road.

In addition, this tire comprises a carcass reinforcement which is anchored in the beads and which extends in the sidewalls and in the crown portion of the tire. This carcass reinforcement, formed of one or more layers of reinforcements, is surmounted radially outwardly in the crown portion of the tire by a crown reinforcement itself formed by a plurality of reinforced layers.

[0004] Among the reinforced layers of the crown reinforcement there are at least two working layers, each of these working layers comprising a plurality of reinforcing elements such as wires or metal cables with low extensibility and parallel in each layer of work and crossed from one working layer to the next by making an angle between 10 ° and 45 ° with the circumferential direction.

In the crown reinforcement, the working layers may be covered by at least one protective layer, each protective layer being formed of advantageously elastic reinforcing elements, ie having greater comparative extensibility. to that of the reinforcing elements of the working layers. Radially on the outside of the crown reinforcement is placed a tread intended to come into contact with a roadway in the contact area between said roadway and the tire.

Definitions: [0007] A radial direction is a direction intersecting the axis of rotation of the tire and perpendicular to it. A radial distance is measured in a radial direction.

An axial direction or transverse direction designates a direction which is parallel to the axis of rotation of the tire. By circumferential direction means a direction that is tangent to any circle centered on the axis of rotation. This direction is perpendicular to both the axial direction and a radial direction.

The tread surface of a tread designates the surface of the tread capable of coming into contact with the roadway when driving. The outer surface of a tire comprises the running surface and the other visible surfaces of the tire when it is mounted on a rim under conditions of use.

It is known that tires for heavy vehicles, especially those used on poor quality road networks, can suffer aggression during driving or maneuvering. These same tires can also come, during urban driving, in contact with sidewalks that under certain conditions can be assaulted and injure one of the flanks. These attacks are the result of obstacles coming to indent one side of a tire.

These attacks can have the effect of violently urge the carcass reinforcement and the crown reinforcement or even to go to cause breaks in the rubber material present between reinforcements of the carcass reinforcement that can lead to a rapid loss of pressure in the tire. This is of course highly detrimental to the life of the tires since the flanks are very often unrepairable, the breaks propagating between the cables of the carcass reinforcement reinforcing the flanks. These same attacks, without causing breakage at the moment of contact with an obstacle, may affect the resistance of the tire to repeated bending; this is due to the large deformations experienced by the materials at the moment of contact with an obstacle.

These attacks are carried out in the portion of the sidewall which is close to the edges of the crown reinforcement, this part of the sidewall being that where we can see a fairly strong variation in thickness of material between the carcass reinforcement. and the outer surface of the tire.

To this known problem, it has already been proposed solutions, but there is still a need for performance improvement. Particularly known is the application WO2009 / 029088 which describes a tire for off-road use, this tire being provided with a plurality of protection blocks on its sidewalls. These protection blocks have side walls inclined so as to avoid any attachment with an external object. The blocks are arranged on at least two circles concentric with the axis of rotation so as to be placed alternately but without contact between them.

Also known is the application US2013 / 0092308-A1 which describes a tire whose flanks are provided with a plurality of blocks on the sidewalls, these blocks having a solid shape and are placed on two circumferential lines next to each other. others on each line with sufficient space so that each block of a line is partially inserted between two blocks of the other line and deforms freely.

WO2016 / 062623 discloses a tire of which at least one of the flanks comprises a plurality of relief patterns, each relief pattern being provided with an appropriate separation zone to close and generate contact forces when the relief pattern is attacked by an external body like a stubble. The document US2013 / 139936 discloses a tire whose flanks comprise a series of protuberances formed on two circumferential lines, the protuberances located closest to the axis of rotation of the tire being of lesser height than the other protuberances. If these solutions have shown interest, it was found that under certain conditions, these solutions still needed to be perfected.

BRIEF SUMMARY OF THE INVENTION

The present invention aims to provide a tire whose at least one sidewall is protected from external aggression experienced during contact with an obstacle during taxiing. This contact on the outer wall of one of the flanks results in a violent force of which one component is directed in a direction pointing inwardly of the inner cavity of the tire and another component directed in a circumferential direction. To this end, the subject of the invention is a tire for a vehicle intended to carry heavy loads, this tire comprising a carcass reinforcement having reinforcements embedded in a rubber material, this tire comprising a top portion comprising a tire strip. bearing defined axially by edges, this tread being intended to be in contact with a ground during rolling, the top part comprising a crown reinforcement and being extended axially on both sides by sidewalls, these sidewalls being - even extended by beads intended to come in contact with a rim.

This tire is further provided with a device for protecting at least one side against external aggressions, this protection device comprising a plurality of raised elements formed on the sidewall to be protected, these elements in relief being disposed in the circumferential direction along at least a first circumferential line and a second circumferential line, the first circumferential line being closest to the edges of the tread of the tire. Each element in relief of the same circumferential line of index i has the same maximum height Hi measured with respect to the surface of the side on which it is formed. By definition, the index i of the first circumferential line is equal to 1; on this first circumferential line are formed relief elements of maximum height H1.

The relief elements of the protective device are such that the maximum heights Hi of the relief elements of the successive circumferential lines going from the first circumferential line index 1 to the following are decreasing. This means that the maximum height H1 of the relief elements of the first circumferential line is greater than the maximum height H2 of the relief elements of the second circumferential line, the latter maximum height H2 being itself larger than the maximum height H3 of the relief elements of the third circumferential line and so on.

In addition, this tire is such that each relief element comprises an intermediate region of elongate shape and having two ends, this intermediate region being extended at each of its two ends, by an extension which is not aligned with the intermediate region of the relief element.

Advantageously, but not necessarily, the extensions of the relief elements of the first line have heights that are greater than the heights of the extensions of the relief elements of the second line.

According to an interesting variant, each extension of a relief element of the device makes an angle B at least equal to 25 ° with the circumferential direction along which is oriented the intermediate portion of said relief element.

In an interesting variant, the extensions of the relief elements of the first circumferential line are directed from the intermediate portion of each element to the axis of rotation of the tire while the extensions of the relief elements of the second circumferential line are directed from the middle portion of each element of the second line to the tread.

According to another variant, in the case where the extensions of the relief elements of the first and second circumferential lines are oriented in opposition, it is advisable that there is an overlap of the extensions of a relief element of the first line by two relief elements of the second line.

What is indicated for two circumferential lines of relief elements may be completed by a third line or a fourth circumferential line.

Preferably, the first circumferential line of relief elements is located on the sidewall so that these relief elements are placed radially. inwardly with respect to an enveloping surface and extending axially outwardly the last layer of the crown reinforcement.

It is advisable to provide that relief elements of a circumferential line can not come into contact with the relief elements of a neighboring circumferential line.

It is also also advisable to form on each element of relief of at least the first circumferential line a cut extending from the outer surface of the relief element in its thickness to generate frictional forces. during a possible contact with an obstacle during taxiing in the image of what is described in the document published under the number WO2016 / 062623. This cut can extend partially or entirely on the intermediate portion and on the extensions of a relief element.

Preferably, the average circumferential length overall of each element in relief is at least equal to 20 mm and at most equal to 150 mm.

Preferably, the height of the relief elements of the first circumferential line is at least equal to 3 mm and at most 15 mm. The height reduction of the relief elements from one circumferential line to the next is at least 10% of the height of the tallest elements.

Preferably, the width of the relief elements is at least equal to half their height and at most three times that same height.

Each element of relief of a circumferential line may have its intermediate portion circumferentially oriented or make a non-zero angle with the circumferential direction; in the latter case, the average angle of the intermediate portion is not more than 20 degrees with the circumferential direction.

BRIEF DESCRIPTION OF THE FIGURES

[0040] Figure 1 shows a partial view of a tire according to one embodiment of the invention; Figure 2 shows a sectional view of a sidewall of the tire shown in Figure 1;

Figure 3 shows in section a variant of a sidewall comprising a protection device according to a variant of the invention. DESCRIPTION OF THE FIGURES

Figure 1 shows a partial view of a tire 1 for a heavy vehicle of size 295/80 R 22.5 and comprising a protection device 10 of a sidewall 30 according to a first embodiment of the invention. The tire 1 shown comprises a crown portion 20 extended on either side by flanks 30, these flanks 30 being connected to beads 40 intended to come into contact with a tire mounting rim (not shown here).

The tire 1 is reinforced by a carcass reinforcement 31 constituted by a plurality of reinforcements. In the present case, these reinforcements are anchored in each bead 40 on bead reinforcements 41 and extend from bead to bead passing through the flanks and the upper part 20.

In the case described, only the sidewall 30 to be positioned so as to be visible from the outside of the vehicle on which is mounted the tire is provided with a protective device 10 of said sidewall. Of course, the present invention can be implemented on both sides of the same tire. The uppermost portion 20 comprises, radially outside the carcass reinforcement 31, a crown reinforcement 22 and radially outwardly a tread 21 whose surface is intended to serve as a running surface 200 to come into contact with a roadway while driving.

On the sidewall 30 there is a protective device 10 against external aggressions that can be generated by rigid bodies against which said sidewall of the tire can come into contact during travel.

The protection device 10 comprises a plurality of first relief elements 101 and second relief elements 102 arranged respectively on a first circumferential line C1 and a second circumferential line C2. Each circumferential line is a circle centered on the axis of rotation of the tire.

The first circumferential line C1 has a radius R1 greater than the radius R2 of the second circumferential line C2; this first circumferential line C1 is located between the second line C2 and one of the edges 210 of the tread 20 of the tire. The relief elements 101 formed on this first circumferential line C1 have a U-shaped geometry returned comprising a medially oriented middle intermediate portion and having an average length equal to 75 mm and a width equal to 11 mm. Each intermediate portion 101 is extended on either side by extensions, these extensions being oriented towards the axis of rotation of the tire relative to said middle intermediate portion.

These extensions each form with the intermediate portion an angle A which in this case is equal to 120 °. In this case the angle B with the circumferential direction of each extension is equal to 60 °. These extensions have lengths - here equal to 15 mm - suitable for mechanically supporting the intermediate portion when the latter is subjected to the contact forces with an external obstacle to the rolling tire. In the case in point, an offset D equal to 10 mm is created between the intermediate portion and the end of each extension. The circumferential distance between each relief element 101 is sufficiently small and appropriate to prevent any body from being able to directly attack the sidewall.

In this variant, the first circumferential line C1 of relief elements 101 is located on the sidewall so that these relief elements carried on this first line are placed radially inward with respect to an enveloping surface. (indicated in Figure 2 by the line S representing the section of this surface with the plane of Figure 2) and extending axially outwardly the crown reinforcement 22. On the second circumferential line C2 are arranged the relief elements 102 of elongated shape and comprising at their ends oblique extensions with respect to the circumferential direction; these elements have a geometric shape substantially identical to that of the first relief elements of the first circumferential line. These oblique extensions are oriented towards the relief elements 101 of the first circumferential line C1.

The relief elements 101 of the first circumferential line C1 are arranged on the sidewall 30 of the tire so as to be offset circumferentially relative to the relief elements 102 of the second circumferential line C2 so as to create a kind of dam to any body coming to pass between two consecutive relief elements 101 of the first circumferential line.

Each element of relief 101 of the first circumferential line C1 has a height H1 in this case constant and equal to 5 mm. This height H1 is measured relative to the external surface 300 of the sidewall 30.

The relief elements 102 formed on the second circumferential line C2 have a U-shaped geometry inverted with respect to that of the elements of the first circumferential line: a medially oriented intermediate intermediate portion circumferentially extended on either side by extensions, these extensions being oriented towards the relief elements 101 of the first circumferential line.

The total average length of each relief element 102 of the second circumferential line is equal to 72 mm, and its average width equal to 11 mm.

Each element of relief 102 of the second circumferential line has a height H2 in this case constant and equal to 3 mm. This height H2 is measured relative to the outer surface 300 of the sidewall 30.

In the variant shown, the relief elements of each circumferential line are not intended to come into contact with the relief elements of the other circumferential line. However, it would be possible to predict that these elements could come into contact with each other. With this reduction of the heights of the relief elements according to their position relative to the tread surface of the tread and the presence of obliquely oriented extensions relative to the intermediate portions of the relief elements, it is possible to to limit the additional volumes of material while reducing the effects of a contact against bodies coming to attack the sidewall while driving.

FIG. 2 represents a cross-sectional view of the sidewall of the tire shown in FIG. 1. In this figure, a first relief element 101 and a second relief element 102 are located in relief on the outer surface 300 of the side wall 30. respectively on a first circumferential line C1 of radius RI and a second circumferential line C2 of radius R2, this second radius R2 being smaller than the radius R1.

The relief element 101 has an outer surface 1010 whose all points are located at a constant distance H1 from the outer surface 300 of the sidewall. The relief element 102 has an outer surface 1020 whose all points are at a constant distance H2 from the flank surface. In a variant not shown, each relief element of the sidewall protection device comprises a separation zone made in the form of an incision of appropriate width so that this incision can close during contact with a foreign body and thus generate a friction force. This incision is oriented substantially in the circumferential direction in the intermediate region and extends over the entire length of each extension so as to generate frictional forces between the facing faces delimiting this incision when one said relief elements come into contact with an external body.

Figure 3 shows in section another variant of a sidewall comprising a protection device according to the invention. According to this variant, the outer surfaces 1010 and 1020, relief elements 101, 102 respectively, are inclined relative to the profile of the outer surface 300 of the sidewall. Each first relief element 101 has ridges 1011 and 1012 limiting the outer surface 1010, the edge 1011 located on the side of the edge 210 of the tread being located at a distance H1 of the outer surface of the sidewall which is greater than the distance H12 from the other edge 1012 measured with respect to the same surface. It is the same for the second relief element 102 which has edges 1021 and 1022 limiting the outer surface 1020, the edge 1021 located on the side of the first relief element 101 being located at a distance H21 from the surface external side of the sidewall which is greater than the distance H22 of the other edge 1022. In this variant, the maximum height H21 of each second element 102 is less than the minimum height H12 of each first element 101.

The description of two variants of the invention, for the sole purpose of understanding the invention, can not of course limit the scope of this invention which is defined by the claims and the person skilled in the art is able to to adapt to his needs the parameters of the invention.

Claims

A tire (1) for a vehicle intended to carry heavy loads, said tire comprising a carcass reinforcement (31) having reinforcements embedded in a rubber material, said tire comprising a crown portion (20) comprising a tread (21). ) delimited axially by edges (210), this tread being intended to be in contact with a ground during rolling, the top portion (20) comprising a crown reinforcement (22) and being extended axially on both sides other by flanks (30), these flanks being themselves extended by beads (40) intended to come into contact with a rim, this tire being provided with a protection device (10) of at least one flank against external aggressions, this protection device (10) comprising a plurality of raised elements formed on the sidewall to be protected, these relief elements being arranged in the circumferential direction along at least a first circumferential line ntielle (Cl) and a second circumferential line (C2), the first circumferential line being the closest to the edges (210) of the tread of the tire, each element in relief of the same circumferential line of index i having a same maximum height Hi measured with respect to the surface of the sidewall on which it is formed, the index i of the first circumferential line is equal to 1, on this first circumferential line (C1) are formed relief elements (101) of maximum height H1, the maximum heights Hi of the relief elements (102) of the successive circumferential lines going from the first circumferential line to the following are decreasing, this tire being characterized in that each relief element comprises an intermediate region of shape elongated in the circumferential direction, this intermediate region comprising two ends and being extended at each of its two extremities by an extension forming a non-zero angle B with the circumferential direction.

2- Tire according to claim 1 characterized in that each extension of a relief element (101, 102) of the protective device (10) makes an angle B at least equal to 25 ° with the circumferential direction.

3- tire according to claim 1 or claim 2 characterized in that the extensions of the relief elements (101) of the first circumferential line (C1) are directed from the intermediate portion of each element to the axis of rotation of the tire while that the extensions of the relief elements (102) of the second circumferential line (C2) are directed from the intermediate portion of each element of the second line to the tread 4- Tire according to any one of claims 1 to 3, characterized in that the first circumferential line (C1) of relief elements (101) is located on the sidewall so that these relief elements are placed radially inward with respect to an enveloping surface (S) and extending axially outwardly the crown reinforcement (22).

5- Tire according to any one of claims 1 to 4 characterized in that the relief elements of each circumferential line can not come into contact with relief elements of a neighboring circumferential line. 6- tire according to any one of claims 1 to 5 characterized in that on each element of relief (101) of at least the first circumferential line (Cl) there is formed a cut opening on the outer surface of the element of relief and prolonged in its thickness. 7- tire according to any one of claims 1 to 6 characterized in that the width of the relief elements (101, 102) is at least equal to 0.5 times their height (Hl, H2) and at most 3 times the same height (H1, H2).

8- tire according to any one of claims 1 to 7 characterized in that the height of the relief elements (101) of the first circumferential line (Cl) is at least equal to 3 mm and at most 15 mm.