Tyre comprising sidewall insert

Abstract

The invention relates to a tyre (1) for a lightweight vehicle, the tyre (1) being able to be fitted with a sidewall insert (9), the tyre (1) comprising a curb protection device (32) having an edge (321), the edge (321) being the axially outermost region of the sidewall, the measurement being carried out on a tyre mounted on a rim (2) at a pressure of 2 bar. The sidewall (3) comprises anchoring means (6) having a circumferential mean line (61) and intended to engage at least with the sidewall insert (9). The circumferential mean line (61) of the anchoring means (6) is located radially inward of the edge (321) of the curb protection means (32).

Description

Technical Field

[0001] The present invention relates to a tyre, more particularly intended to be mounted on light four-wheeled vehicles (motor vehicles, vans) or two-wheeled vehicles (motorcycles), and comprising at least one sidewall having a sidewall insert intended to personalize the design of the tyre sidewall. Background Art

[0002] There is a continuing interest among vehicle manufacturers and users in personalizing the design of the tire sidewall using color devices and / or additional elements (referred to in this document as inserts).

[0003] Because a tire exhibits a geometry that is a function of rotation about an axis of rotation, its geometry is typically described in a meridian plane containing the tire's axis of rotation. For a given meridian plane, the radial, axial, and circumferential directions refer to the directions perpendicular to the tire's axis of rotation, parallel to the axis of rotation, and perpendicular to the meridian plane, respectively. The circumferential direction is tangential to the tire's circumference.

[0004] Hereinafter, the expressions "radially inside" and "radially outside" mean "closer to the tire's axis of rotation" and "further away from the tire's axis of rotation," respectively. "Axially inside" and "axially outside" mean "closer to the tire's equatorial plane" and "further away from the tire's equatorial plane," respectively, where the tire's equatorial plane is the plane passing through the middle of the tread surface and perpendicular to the axis of rotation. "Element A is axially located at an axial distance D inside of element B" means that element A is closer to the equatorial plane than element B, and the axial distance between the two elements is equal to distance D. This type of phraseology can be extended to both radial and circumferential directions, as well as to exterior and interior positions of one element or the other.

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

[0006] The "bead" of a tire means the portion of the tire that is intended to be mounted to the rim.

[0007] The radial tire also comprises a reinforcement composed of a crown reinforcement radially on the inside of the tread and a carcass reinforcement radially on the inside of the crown reinforcement.

[0008] A known color device for personalizing the sidewall of a tire is a colored rubber composition (e.g., a white rubber composition) that is present in the sidewall of the tire and contrasts with the black color of the adjacent rubber composition. However, this technical solution has several disadvantages. First, certain chemical components (e.g., protective components) present in the rubber composition adjacent to the color device may migrate toward the colored rubber composition and cause the colored rubber composition to gradually lose color over time. In addition, over the entire service life of the tire, deformation of the sidewall may cause the colored rubber composition to begin to crack and deteriorate its appearance. Moreover, the mechanical device used to mount the tire to its rim may also degrade the colored rubber composition through friction. Finally, from an industrial perspective, manufacturing a tire that includes portions of different colors is more complicated.

[0009] Document WO 2022 / 069832 A1 describes an insert in the form of a tire decorative element, which is intended to be removably engaged in the sidewall. The decorative element is more specifically located radially outside the edge of the curb rib. However, this decorative element is prone to deformation and detachment from the sidewall, in particular when subjected to curb impact or cornering under high lateral loads. In addition, this insert causes aerodynamic drag, which is particularly disadvantageous at high speeds (in particular, greater than 120 km / h). Tires of this type of insert are more particularly of interest for luxury sports cars with a speed rating of at least S (180 km / h). Summary of the Invention

[0010] The inventors aim to disclose a tire that can be fitted with at least one sidewall insert having improved sidewall mounting and attachment, capable of resisting curb impacts and scrapes, and capable of cornering under high lateral loads, while significantly reducing the aerodynamic drag of the insert.

[0011] This object has been achieved by a tire for light vehicles, intended to be mounted on a wheel rim and capable of being equipped with at least one sidewall insert, comprising:

[0012] - two sidewalls respectively connecting the crown to two beads, each intended to come into contact with the rim,

[0013] - at least one sidewall comprises, on its axially outer sidewall, a curb rib having an edge, said edge being the axially outermost area of ​​the sidewall, the measurement being made on the tyre mounted on the rim at a pressure of 2 bar,

[0014] - at least one sidewall also comprises anchoring means intended to cooperate with at least one sidewall insert,

[0015] - the anchoring means extends circumferentially in the circumferential direction (XX') of the tire and comprises at least one recess formed on an axially outer layer of the sidewall comprising at least one rubber material, said recess extending axially towards the interior of the sidewall from the axially outer sidewall,

[0016] - the anchoring device has a circumferential mean line,

[0017] The circumferential mean line of the anchoring device is located radially inside the edge of the curb rib.

[0018] The principle of the present invention is to provide an anchoring device for a sidewall insert, comprising at least one circumferential recess formed in the axially outer sidewall ply. The recess always comprises at least two walls connected by a bottom surface. The circumferential recess in the sidewall comprises at least one radially outermost circumferential wall and one radially innermost circumferential wall. Thus, the anchoring device 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 recess.

[0019] The anchoring means may comprise a protrusion formed in the recess or between two recesses to increase the mechanical strength of the insert, in particular during rolling, or to improve the positioning of the insert, in particular the centering of the insert when it is mounted.

[0020] The tire according to the present invention also includes a curb rib on the sidewall to protect the carcass from impacts or scrapes on the sidewall, particularly from impacts with curbs. The curb rib is therefore the axially outermost region of the tire. It consists of a circumferential excess thickness of rubber, sometimes tapered, with a maximum radial thickness of approximately 5 mm at a radial height of 15 mm. The curb rib may include an axial excess thickness of rubber that varies circumferentially, with projections, ridges, or any other pattern. The excess thickness is measured on the tire sidewall as the difference between the local distance between the axially innermost carcass layer and the outer surface of the sidewall (i.e., the surface in contact with the outside air) and the average value of this distance. For the curb rib, this thickness difference first increases and then decreases by a radial thickness of between approximately 2 mm and 5 mm over a radial height of approximately 10 mm to 15 mm of the sidewall height. The edge of the curb rib is not necessarily protruding, as the rib may be chamfered or rounded. The distance between the axially outermost carcass layer and the outer surface of the sidewall is measured on a meridian cross-section.

[0021] The anchoring device, and therefore the recess, may be circumferentially continuous or circumferentially discontinuous (i.e., formed of separate circumferential portions). The mean circumferential line of the anchoring device is located at the mean radius between the radius of the radially outermost circumferential wall and the radius of the radially innermost circumferential wall, where they intersect the outer surface of the sidewall. If a fillet exists where these surfaces intersect, the radius of each circumferential wall is considered to be radially equidistant from the two ends of the fillet in question. The mean circumferential line of the discontinuous recess is calculated over the portion of the tire where the recess exists.

[0022] The recess also enables the sidewall insert to be engaged in the thickness of the sidewall without creating a significant protrusion relative to the axially outer sidewall, and therefore without disturbing the air flow near the sidewall in this area.

[0023] Unlike the prior art, the principle of the invention is that the anchoring device capable of receiving the insert is located radially inside the curb rib, since, surprisingly, this position provides better protection of the insert against tearing, among other advantages of the invention.

[0024] The axially outer sidewall layer formed with the anchoring device extends axially from the axially outer sidewall (which is in contact with the atmospheric air) to the axially outermost reinforcing layer (which is formed by a reinforcement body that is generally a textile). More specifically, the axially outer sidewall layer is in contact with the rubber compound (generally referred to as the coating compound) that coats the reinforcement body of the axially outermost reinforcing layer on the axially inner side.

[0025] The recess serves to anchor the insert in the sidewall by locking its edges between its walls. Thus, it helps to secure the sidewall insert (which tends to pop out during rolling).

[0026] According to the invention, the preferred solution is that, when the tire is mounted on a rim having a diameter D (in mm), the circumferential mean line of the anchoring device is located, in any meridian plane (YZ), at a diameter D1 that is at least D+44 mm and at most D+80 mm, preferably at most D+70 mm. The goal is to position the insert in the optimal area of ​​the sidewall between the rim and the curb rib.

[0027] According to one embodiment of the invention, the edge of the curb rib has a radial distance of at least 4 mm from the circumferential mean line of the anchoring device in order to optimize the protective effect of the curb rib, in particular protecting the insert from curb impacts.

[0028] To optimize the effect of the insert relative to the tyre, it is advantageous if the edge of the curb rib is situated 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.

[0029] Furthermore, this position of the anchoring device reduces its likelihood of being subject to wear caused by friction between the insert and the recess wall, since it is not located in the area of ​​the sidewall subject to the greatest bending. In practice, the sidewall deforms during use, particularly when it passes directly through the area of ​​contact with the ground. This deformation is compounded by the rigidity of the rim and the bead wire. Due to the difference in radius and the fact that the insert is not part of the tire, the walls of the recess and the insert deform differently, resulting in movement and friction in their contact area, and thus wear. The proposed proposal significantly reduces this phenomenon. The diameter D of the rim is defined by the commonly used tire-related standards, such as, for example, the European Tire and Rim Technical Organization (ETRTO) standards.

[0030] Due to its special shape, a protrusion formed in the recess from the bottom of the recess and intended to contact the axially inner face of the sidewall insert can better anchor the sidewall insert. One solution for such a protrusion is a substantially mushroom-shaped protrusion, in which the stem is axially located inside the head (which is the portion with the greater radial width). This protrusion configuration allows the sidewall insert to be effectively snapped onto the protrusion and ensures that the sidewall insert remains in place during rolling, even under the mechanical bending and centrifugal loads applied to the tire.

[0031] A thickness of 1 mm is the minimum thickness of the layer of rubber material to ensure mechanical decoupling between the sidewall insert (intended to engage in said recess) and the nearest axially inner reinforcement. This minimum thickness prevents loads from concentrating at the bottom of the recess.

[0032] Preferably, the recess is formed in an axially outer sidewall layer made of a single rubber material.

[0033] Advantageously, recesses are not formed in composite material layers which are made of superposed materials and which may therefore be susceptible to mechanical strength issues at the interfaces between said materials.

[0034] Advantageously, a straight line included in any meridian plane and passing respectively through the two points of intersection of each recess wall with the axial outer tread forms an angle with the radial direction equal to at most 25°, preferably at most 15°.

[0035] If the angle A is greater than 25°, the axially outer flank becomes excessively inclined relative to the radial direction in the region of the anchoring device generally close to the tire bead. Consequently, the insert becomes less visible and less effective.

[0036] The sidewall insert is intended to cooperate with the anchoring device according to any one of the embodiments of the tyre described above, by engagement in a recess of the anchoring device and optionally by snap-fitting (if the anchoring device is provided with protrusions).

[0037] If the anchoring means comprises a protrusion with an outer meridian profile, the sidewall insert preferably has an inner meridian profile substantially parallel to the outer meridian profile of the protrusion. In other words, in this configuration, the sidewall insert has a mushroom shape that constitutes a concave portion in which the convex mushroom shapes of the protrusion interlock, thus providing good anchoring.

[0038] According to a preferred embodiment, the sidewall insert comprises at least one polymeric material, such as an elastomeric material, rubber, silicone or a thermoplastic material.

[0039] The material or materials from which the sidewall insert is made must be sufficiently deformable so as not to generate excessive loads at the interface between the sidewall insert and the anchoring device, which could easily lead to wear of the insert. Polymeric materials (such as elastomeric materials, rubber, silicone or thermoplastic materials, this list not being exhaustive) will meet this requirement.

[0040] The sidewall insert preferably has a different color and / or texture than the sidewall comprising the anchoring means.Since the object of the invention is to personalize the design of the tire sidewall, the sidewall insert preferably has a different color and / or texture relative to the sidewall.

[0041] The sidewall insert, which is preferably coloured, may have one or more colours different from the normally black colour of the sidewall. It is also preferred that the sidewall insert is of a single colour in order to simplify its manufacture. The sidewall insert may be circumferentially continuous or integral.

[0042] According to a particular variant embodiment, in order to further distinguish the sidewall insert from the sidewall, the sidewall insert is covered with a graphic or texture capable of creating a contrasting effect (for example a microtexture or a velvet texture), or is solid colored.

[0043] Preferably, the tire is asymmetric, preferably non-directional, and includes an anchoring device intended to cooperate with at least one sidewall insert on only one of the tire's two sidewalls. Having an insert on the sidewall situated on the inside of the vehicle is irrelevant since it would not be visible. It is therefore advantageous to have the anchoring device on only one sidewall of the tire. The tire is therefore already asymmetric due to its sidewalls and therefore, according to the manufacturer's recommendations, it is advantageous to find this asymmetry in the tread pattern on the side of the tread situated on the outside of the vehicle. In order to avoid having two tires (one for the right side of the vehicle and one for the left side of the vehicle), it is advantageous for the tire to be non-directional. Therefore, in order to comply with the tire's axial symmetry, it is only necessary to rotate the right tire relative to the left tire on a single axis so that the right tire is symmetrical about a plane perpendicular to the axis of the left tire.

[0044] Finally, the invention relates to an assembly consisting of a tyre according to any one of the embodiments of the tyre described above and at least one sidewall insert according to any one of the embodiments of the sidewall insert described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] pass Figure 1 Shows the characteristics of the present invention, the Figure 1 are schematic and not drawn to scale. DETAILED DESCRIPTION

[0046] Figure 1 To illustrate the radial half-section of a tire 1 according to the present invention, the tire 1 is mounted on a rim 2 having a diameter D and fitted with sidewall inserts 9 that snap into place in the sidewalls 3. The sidewalls 3, which each connect the crown 4 to the beads 5, include, on their axially outer sidewalls 31, a curb rib 32 having an edge 321 located at a diameter D2. This edge 321 is the axially outermost region of the sidewall. The sidewall 3 also includes an anchoring device 6 comprising at least one recess 7 and intended to engage with the sidewall insert 9. The anchoring device 6 has a circumferential mean line 61 having a diameter D1. The circumferential mean line 61 is radially located inwardly of the edge 321 of the curb rib 32 and at a radial distance d therefrom. The radial distance d is at least 4 mm. A straight line T passing through the two intersection points 71 and 72 of each recess wall with the axially outer tread 31 respectively forms an angle A with the radial direction (ZZ′) equal to at most 20°, preferably at most 15°.

[0047] The inventors have studied the invention more particularly for a tire having dimensions 275 / 35R 21 103Y XI, intended to be inflated to a recommended pressure equal to 2.9 bar and to carry a maximum load equal to 875 kg.

[0048] A tire according to the invention was compared with a control tire according to the prior art. The anchoring devices of both tires had the same geometry, including the inserts that snap onto the protrusions. Only the position of the anchoring devices relative to the curb rib varied. According to the invention, the mean line of the anchoring devices was located 7 mm from the curb rib edge and radially inward of the curb rib. In the control tire, the mean line of the anchoring devices was located 4 mm from the curb rib edge and radially outward of the curb rib.

[0049] Those skilled in the art will appreciate that the position of the insert in the tyre according to the invention means that the edge ribs of the insert are concealed and therefore the aerodynamic drag of the invention is significantly less than that of the control tyre on most vehicles.

[0050] Tests conducted under sporting conditions on a circuit with sharp turns resulted in maximum lateral loads exceeding 1 g over a distance of 50 km, leading to partial displacement of the anchoring device on the control tire. The same tests conducted on tires according to the invention showed that the insert remained engaged on the tires according to the invention along its entire length.

[0051] These tests demonstrate the benefits of the present invention.

Claims

1. A tyre (1) for lightweight vehicles, said tyre (1) being intended to be mounted on a rim (2) and being capable of being fitted with at least one sidewall insert (9), said tyre (1) comprising: - two sidewalls ( 3 ) connecting the crown ( 4 ) to two beads ( 5 ) each intended to come into contact with the rim ( 2 ), - at least one sidewall (3) comprises, on its axially outer sidewall (31), a curb rib (32) having an edge (321), said edge (321) being the axially outermost area of ​​the sidewall, the measurement being carried out on a tire mounted on the rim (2) at a pressure of 2 bar, - said at least one sidewall (3) further comprises anchoring means (6) intended to cooperate with at least one sidewall insert (9), - said anchoring device (6) extends circumferentially in the circumferential direction (XX') of the tire and comprises at least one recess (7) formed on an axially outer layer of a sidewall (3) comprising at least one rubber material, said recess (7) extending axially from an axially outer sidewall (31) towards the interior of the sidewall (3), - the anchoring device (6) has a circumferential mean line (61), - Characterized in that the circumferential mean line (61) of the anchoring device (6) is located radially inside the edge (321) of the curb rib (32).

2. Tyre (1) according to claim 1, intended to be mounted on a rim having a diameter D in mm, wherein In any meridian plane (YZ), the circumferential mean line (61) of said anchoring device (6) is located at a diameter D1 at least equal to D+44 mm and at most equal to D+80 mm, preferably at most equal to D+70 mm.

3. The tire (1) according to any one of claims 1 and 2, wherein: The radial distance (d) between the edge (321) of the curb rib (32) and the circumferential mean line (61) of the anchoring device (6) is at least 4 mm.

4. Tyre (1) according to any one of claims 1 to 3, intended to be mounted on a rim having a diameter D in mm, wherein The edge (321) of the curb rib (32) is located 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. The tire (1) according to any one of claims 1 to 4, wherein: A straight line (T) included in any meridian plane (YZ) and passing through the two intersection points (71, 72) of the radially outermost circumferential wall and the radially innermost circumferential wall of the recess (7) with the axially outer tire side surface (31) forms an angle (A) with the radial direction (ZZ') of at most 20°, preferably at most 15°.

6. The tire (1) according to any one of claims 1 to 5, wherein: The tyre is asymmetric, preferably non-directional, and comprises anchoring means (6) intended to cooperate with at least one sidewall insert (9) on only one of the two sidewalls of the tyre.

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

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