Tyre comprising a sidewall insert

Abstract

The present invention relates to a tyre (1) for a light vehicle, capable of being equipped with a sidewall insert (9), the tyre (1) comprising a curb guard (32) having an edge (321), which is the axially outermost zone of the sidewall, the measurement being taken on the tyre mounted on a rim (2) at a pressure of 2 bar. The sidewall (3) comprises an anchoring means (6), having a circumferential mean line (61), intended to engage with at least the sidewall insert (9). The circumferential mean line (61) of the anchoring means (6) is positioned radially inside the edge (321) of the curb guard (32).

Description

Tire including a sidewall insert

[0001] The present invention relates to a tire, intended more particularly to equip a light four-wheeled vehicle (car, van), or two-wheeled vehicle (motorcycle), and comprising at least one sidewall with a sidewall insert, intended to personalize the design of the tire sidewall.

[0002] A constant concern of vehicle manufacturers and users is to personalize the design of tire sidewalls by colored means and / or additional elements, called inserts in this document.

[0003] A tire having a geometry of revolution with respect to an axis of rotation, the geometry of the tire is generally described in a meridian plane containing the axis of rotation of the tire. For a given meridian plane, the radial, axial and circumferential directions respectively designate the directions perpendicular to the axis of rotation of the tire, parallel to the axis of rotation of the tire and perpendicular to the meridian plane. The circumferential direction is tangent to the circumference of the tire.

[0004] In the following, the expressions "radially inward", respectively "radially outward" mean "closer", respectively "further from the axis of rotation of the tire". By "axially inward", respectively "axially outward", is meant "closer", respectively "further from the equatorial plane of the tire", the equatorial plane of the tire being the plane passing through the middle of the rolling surface and perpendicular to the axis of rotation. By "an element A axially inward to an element B by an axial distance D", is meant that element A is closer to the equatorial plane than element B and that the axial distance between the two elements is equal to the distance D. This type of sentence can be generalized with the radial and circumferential direction and the outer versus inner position of one or the other of the elements.

[0005] Generally speaking, a tire comprises a tread, intended to come into contact with the ground via a rolling surface, the two axial ends of which are connected via two sidewalls with two beads ensuring the mechanical connection between the tire and the rim on which it is intended to be mounted.

[0006] By "bead" of a tire, we mean a part of the tire intended to sit on a wheel rim.

[0007] A radial tire further comprises a reinforcing reinforcement, consisting of a crown reinforcement, radially inside the tread, and a carcass reinforcement, radially inside the crown reinforcement.

[0008] A known colored means for personalizing the sidewall of a tire is a colored rubber composition, for example white, contained in the sidewall of the tire and contrasting with the black color of the adjacent rubber compositions. However, this technical solution has a number of disadvantages. First of all, certain chemical components, such as protective components, contained in the rubber compositions adjacent to the colored means, can migrate to the colored rubber composition and cause it to gradually discolor over time. In addition, deformations of the sidewall during the life of the tire can initiate cracks in the colored rubber composition and degrade its appearance. Furthermore, the mechanical means used to mount the tire on its rim, by rubbing on the colored rubber composition, can also degrade it.Finally, the manufacture of a tire comprising portions of differentiated colors is more complex industrially.

[0009] Document WO2022 / 069832 A1 describes an insert in the form of a tire trim element intended to be removably engaged in a sidewall. The trim element is positioned more particularly radially outside the edge of the protective cord. However, this trim element is likely to deform and detach from the sidewall, particularly during impacts against curbs or when cornering with strong transverse thrust. Furthermore, such an insert causes significantly penalizing aerodynamic drag at high speed, namely greater than 120 km / h. However, the tires more specifically concerned by this type of insert are tires for luxury sports cars whose speed index is at least equal to S (180 km / h).

[0010] The inventors set themselves the objective of proposing a tire capable of being equipped with at least one sidewall insert, with mounting and attachment on the sidewall improved resistance to impacts and curb scraping and cornering with strong transverse thrust and significantly reducing the aerodynamic drag of the insert.

[0011] This objective has been achieved by a tire for a light vehicle, intended to be mounted on a rim and capable of being equipped with at least one sidewall insert, said tire comprising: -two sides connecting a summit respectively to two beads, each intended to come into contact with the rim, - at least one sidewall comprising, on its axially outer sidewall face, a protective bead having an edge, being the most axially outer zone of the sidewall, the measurement being taken on the tire mounted on a rim at a pressure of 2 bars, -at least one side comprising an anchoring means, intended to cooperate with at least one side insert, - the anchoring means extending circumferentially, in a circumferential direction (XX') of the tire, and comprising at least one hollow formed in an axially outer layer of the sidewall comprising at least one rubber material, said hollow extending from an axially outer face of the sidewall axially towards the inside of the sidewall, - the anchoring means having a circumferential mean line, - the circumferential mean line of the anchoring means being positioned radially inside the edge of the protective cord.

[0012] The principle of the invention is to have an anchoring means, for a flank insert, comprising at least one circumferential hollow, formed in an axially outer layer of the flank. A hollow always comprises at least two walls connected by a bottom surface. A circumferential hollow on the flank comprises at least one radially outermost circumferential wall and one radially innermost circumferential wall. Therefore the anchoring means comprises at least one radially outermost circumferential wall and one radially innermost circumferential wall, both of which may or may not belong to the same hollow.

[0013] The anchoring means may comprise a protuberance, formed in said hollow or between two hollows to improve the mechanical strength of the insert, in particular when rolling, or to improve the positioning of the insert, in particular the centering when mounting the insert.

[0014] The tire according to the invention also comprises a sidewall protection cord to protect the carcass against impacts or scraping on the sidewall, in particular impacts against curbs. The protection cord is therefore the axially outermost zone of the tire. It consists of a circumferential axial excess thickness of rubber, sometimes pyramidal, with a maximum radial thickness of approximately 5 mm over a radial height of 15 mm. A protection cord may comprise a variable axial excess thickness of rubber in the circumference, with bumps, grooves or any other pattern. The excess thickness is evaluated by considering for the sidewall of the tire, the difference between the local distance between the axially innermost carcass layer and the external surface - namely the surface in contact with the external air - of the sidewall, and the average of this distance.At the level of the protective bead, this difference in thickness increases then decreases over a radial height of the order of 10 mm to 15 mm of the sidewall height, with an axial thickness of approximately between 2 and 5 mm. The edge of the protective bead does not necessarily have to be protruding; the bead may be chamfered or rounded. The measurements of the distances between the axially outermost carcass layer and the outer surface of the sidewall will be made on a meridian section.

[0015] The anchoring means, therefore the hollow, may be circumferentially continuous or circumferentially discontinuous, that is to say formed of circumferential portions which are disjointed from one another. The mean circumferential line of the anchoring means is located at the mean radius between the radius of the most radially outer circumferential wall and the radius of the most radially inner circumferential wall at their junctions with the outer surface of the sidewall. In the event of the existence of a fillet at the junctions between said surfaces, the radius of each circumferential wall will be considered to be radially equidistant from the two ends of the fillet in question. In the event of a discontinuous hollow, the calculation of the mean circumferential line of the hollow will be made on the portions of the tire in which a hollow is present.

[0016] The hollow also allows the flank insert to be engaged in the thickness of the flank, so as not to create a significant protrusion relative to the axially outer face sidewall, and therefore not to disturb the flow of air near the sidewall in this area.

[0017] The principle of the invention is that unlike the state of the art, the anchoring means capable of receiving an insert is radially inside the protective cord because unexpectedly this position protects the insert much better from tearing among other advantages of the invention.

[0018] The axially outer sidewall layer in which the anchoring means is formed extends axially from an axially outer sidewall face, in contact with atmospheric air, to an axially outermost reinforcing layer, formed of reinforcements, most often textile. More precisely, the axially outer sidewall layer is in axially inner contact with the rubber mixture coating the reinforcements of the axially outermost reinforcing layer, usually called the coating mixture.

[0019] The hollow anchors the insert in the sidewall by blocking the edges of the sidewall insert between its walls. It therefore helps to hold the sidewall insert in place, which may be ejected during rolling.

[0020] According to the invention, a preferred solution is that the tire being intended to be mounted on a rim of diameter D in mm, in any meridian plane (YZ), the circumferential mean line of the anchoring means is positioned at a diameter DI at least equal to D+44 mm and at most equal to D+80 mm, preferably at most equal to D+70 mm. This involves positioning the insert in the most optimal area of ​​the sidewall between the rim and the protective bead.

[0021] According to one embodiment of the invention, the edge of the protective cord is at a radial distance from the circumferential mean line of the anchoring means at least equal to 4 mm in order to optimize the protective effect of the protective cord with respect to the insert against sidewalk impacts in particular.

[0022] To optimize the effect of the insert on the tire, it is advantageous for the edge of the protective cord to be positioned at a diameter D2 at least equal to D+52 mm and at most equal to D+96 mm, preferably at most equal to D+86 mm.

[0023] Furthermore, such a position of the anchoring means reduces its potential wear linked to friction between the insert and the walls of the hollow because it is not in the zone of greatest flexion of the sidewall. Indeed, during use, the sidewall deforms, particularly when it passes right through the contact area with the ground. This deformation increases from the rim due to the rigidity of the rim and that of the bead. Having different radii and the insert not being part of the tire, the walls of the hollows and the walls of the insert deform differently, creating movements and friction on their contact areas, thus creating wear. The recommendations given greatly reduce this phenomenon.The diameter D of a rim is defined by the usual standards relating to tires, such as, for example, the standard of the "European Tire and Rim Technical Organization" or "ETRTO" standard.

[0024] A protrusion, formed in the hollow from the bottom of the hollow, intended to come into contact with an axially inner face of the sidewall insert, can allow better anchoring of the sidewall insert thanks to a specific shape. One solution for such a protrusion is to have a substantially mushroom shape, the root of which is the axially inner portion of the head, the portion of greater radial width. This configuration of protrusion allows effective clipping of the sidewall insert on the protrusion and guarantees its maintenance in position during rolling, under the mechanical stresses of bending and centrifugation applied to the tire.

[0025] A thickness of 1 mm is the minimum thickness of the rubber material layer, ensuring mechanical decoupling between the sidewall insert, intended to be engaged in said hollow, and the closest axially internal reinforcement reinforcement. This minimum thickness avoids stress concentrations at the bottom of the hollow.

[0026] Preferably the hollow is formed in an axially outer sidewall layer made of a single rubber material.

[0027] Advantageously, the hollow is not formed in a composite layer, consisting of a superposition of materials, and, therefore, potentially sensitive to problems of mechanical strength of the interfaces between said materials.

[0028] Advantageously, the straight line, contained in any meridian plane and passing through two points of intersection respectively of each hollow wall with the axially external face of the flank, forms, with the radial direction, an angle at most equal to 25°, preferably at most equal to 15°.

[0029] When the angle A is greater than 25°, the axially outer sidewall face becomes too inclined relative to the radial direction, in the area of ​​the anchoring means, generally close to the tire bead. As a result, the insert becomes less visible and loses its appeal.

[0030] The sidewall insert is intended to cooperate with an anchoring means according to one of the previously described tire embodiments, by engagement in the hollow of the anchoring means and possibly by clipping if the anchoring means is provided with a protuberance.

[0031] If the anchoring means comprises a protuberance having an outer meridian profile, the flank insert preferably has an inner meridian profile substantially parallel to the outer meridian profile of the protuberance. In other words, in this configuration the flank insert has a mushroom shape which constitutes a female portion into which the male mushroom shape of the protuberance fits, which ensures good anchoring.

[0032] According to a preferred embodiment, the sidewall insert comprises at least one polymeric material, such as an elastomeric, rubbery, silicone or thermoplastic material.

[0033] The material(s) constituting the flank insert must be sufficiently deformable so as not to generate excessive stresses at the interface between the flank insert and the anchoring means, likely to induce wear of the insert. A polymeric material, such as, but not limited to, an elastomeric, rubber, silicone or thermoplastic material, meets this requirement.

[0034] The sidewall insert preferably has a coloring and / or texture different from those of the sidewall comprising the anchoring means. The objective of the invention being to personalize the design of the tire sidewalls, the sidewall insert preferably has a coloring and / or texture different from the sidewall.

[0035] The preferably colored sidewall insert may have one or more colors differentiated from the usually black color of the sidewall. Preferably again, the sidewall insert is monochrome in order to simplify its manufacture. The sidewall insert may be continuous circumferentially or in pieces.

[0036] According to particular embodiments, to further differentiate it from the sidewall, the sidewall insert is covered with a graphic or texture, for example microtexture or velvet, suitable for creating contrast effects, or tinted throughout.

[0037] Preferably, the tire is asymmetrical and preferably non-directional and includes an anchoring means intended to cooperate with at least one sidewall insert on only one of the two sidewalls of the tire. It is not relevant to have an insert in the sidewall positioned on the inside of the vehicle, because it is not visible. It is therefore advantageous to have an anchoring means only on one sidewall of the tire. The tire is therefore already asymmetrical by its sidewalls, it is therefore advantageous that this asymmetry is found on the sculpture, one side of the tread being to be placed according to the manufacturer's recommendations on the outside of the vehicle. To avoid having two tires, one for the right side and one for the left side of the vehicle, it is advantageous that the tire is not directional.So to respect the axisymmetry of the tire, it is enough to turn the right tire in relation to the left tire on the same axle, so that the right tire is symmetrical in relation to the plane perpendicular to the axle of the left tire.

[0038] The invention finally relates to an assembly consisting of a tire according to any one of the embodiments of the tire previously described, and at least one sidewall insert according to any one of the embodiments of the sidewall insert previously described.

[0039] The characteristics of the invention are illustrated by Figure 1, which is schematic and not shown to scale.

[0040] Figure 1 is a half-meridian section of a tire 1 according to the invention mounted on a rim 2 of diameter D and equipped with a sidewall insert 9 clipped into the sidewall 3. The sidewall 3, connecting the crown 4 respectively to the bead 5, comprises, on its axially outer sidewall face 31, a protective cord 32 having an edge 321 positioned at a diameter D2. This edge 321 is the most axially outer zone of the flank. The flank 3 also comprises an anchoring means 6, comprising at least one hollow 7 and intended to cooperate with the flank insert 9. The anchoring means 6 has a circumferential mean line 61, having a diameter DI. The circumferential mean line 61 is positioned radially inside the edge 321 of the protective bead 32 and at a radial distance d from the edge 321. The radial distance d is at least equal to 4 mm. The straight line T passing through the two points of intersection 71 and 72 respectively of each hollow wall with the axially outer face of the flank 31, forms, with the radial direction (ZZ'), an angle A at most equal to 20°, preferably at most equal to 15°.

[0041] The inventors have more particularly studied this invention for a tire of dimension 275 / 35 R 21 103 Y XL, intended to be inflated to a recommended pressure equal to 2.9 bars and to carry a maximum load equal to 875 kg.

[0042] The tire according to the invention was compared to a control tire according to the state of the art. The anchoring means of the two tires have the same geometry as well as the inserts which are clipped onto protuberances. Only the position of the anchoring means in relation to the protective cord changes. According to the invention the mean line of the anchoring means is at a distance of 7 mm from the edge of the protective cord but radially inside it. In the control tire the mean line of the anchoring means is at a distance of 4 mm from the edge of the protective cord but radially outside it.

[0043] Expert knowledge knowing that the position of the insert for the tire according to the invention masks the position of the edge of the insert by that of the cord allows us to know with certainty that the aerodynamic drag of the invention will be lower than that of the control tire in the majority of vehicles.

[0044] Tests on a sporting use on a circuit with strong bends for maximum lateral thrusts greater than 1 g over a distance of 50 km generated local dislocations outside the anchoring means on the control tire. The same test for the tire according to the invention showed that the insert remained clipped onto the tire according to the invention over its entire length.

[0045] These tests demonstrate the interest of the invention.

Claims

Claims 1. Tire (1) for a light vehicle, intended to be mounted on a rim (2) and capable of being equipped with at least one sidewall insert (9), said tire (1) comprising: -two sides (3) connecting a top (4) respectively to two beads (5), each intended to come into contact with the rim (2), - at least one sidewall (3) comprising, on its axially outer sidewall face (31) a protective bead (32) having an edge (321), being the axially outermost zone of the sidewall, the measurement being made on the tire mounted on a rim (2) at a pressure of 2 bars, -at least one sidewall (3) comprising an anchoring means (6), intended to cooperate with at least one sidewall insert (9), - the anchoring means (6) extending circumferentially, in a circumferential direction (XX') of the tire, and comprising at least one hollow (7) formed in an axially outer layer of the sidewall (3) comprising at least one rubber material, said hollow (7) extending from an axially outer face of the sidewall (31) axially towards the inside of the sidewall (3), - the anchoring means (6) having a circumferential mean line (61), - characterized in that the circumferential mean line (61) of the anchoring means (6) is positioned radially inside the edge (321) of the protective cord (32).

2. Tire (1) according to claim 1, intended to be mounted on a rim of diameter D in mm, in which in any meridian plane (YZ), the circumferential mean line (61) of the anchoring means (6) is positioned at a diameter DI at least equal to D+44 mm and at most equal to D+80 mm, preferably at most equal to D+70 mm.

3. Tire (1) according to one of claims 1 or 2, in which the edge (321) of the protective cord (32) is at a radial distance (d) from the circumferential mean line (61) of the anchoring means (6) at least equal to 4 mm. he 4. Tire (1) according to any one of claims 1 to 3, intended to be mounted on a rim of diameter D in mm, in which the edge (321) of the protective cord (32) is positioned at a diameter D2 at least equal to D+52 mm and at most equal to D+96 mm, preferably at most equal to D+86 mm.

5. Tire (1) according to any one of claims 1 to 4, in which a straight line (T), contained in any meridian plane (YZ) and passing through two points of intersection (71, 72) respectively of the most radially outer circumferential wall and the most radially inner circumferential wall of the hollow (7) with the axially outer sidewall face (31), forms, with the radial direction (ZZ'), an angle (A) at most equal to 20°, preferably at most equal to 15°.

6. Tire (1) according to any one of claims 1 to 5, in which the tire is asymmetrical and preferably non-directional and comprises an anchoring means (6) intended to cooperate with at least one sidewall insert (9) on only one of the two sidewalls of the tire.

7. Assembly consisting of a tire (1) according to any one of claims 1 to 5 and at least one sidewall insert (9) intended to cooperate with the anchoring means (6).

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