Patent Application
20230364949
The present invention relates to a tire, intended more particularly to equip a lightweight four-wheeled vehicle (motor vehicle, 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.
An ongoing concern of vehicle manufacturers and users is to personalize the design of tire sidewalls using coloured means and/or additional elements, referred to as inserts in the present document.
A known coloured means is a coloured rubber composition, for example white in colour, which is present in the sidewall of the tire and contrasts with the black colour of the adjacent rubber compositions. However, this technical solution has a certain number of drawbacks. First of all, certain chemical components, such as protective components, that are present in the rubber compositions adjacent to the coloured means can migrate towards the coloured rubber composition and lead to it gradually losing colour over time. In addition, deformations of the sidewall throughout the service life of the tire can cause cracking to start in the coloured rubber composition and its appearance to deteriorate. Furthermore, the mechanical means used to mount the tire on its rim can also cause the coloured rubber composition to deteriorate by rubbing against it. Lastly, the manufacture of a tire comprising portions of differing colours is more complex in industrial terms.
Among the known inserts, document EP 2692542B1 describes a decorative ring intended to be mounted between the bead of the tire and the rim. However, the mounting of this ring is tricky because of its positioning. In addition, the presence of a ring between a bead of the tire and the rim can modify the mechanical behaviour of the tire, and thus that of the vehicle. Lastly, to install it correctly, this ring runs the risk of requiring adaptation of the geometry of the rim, which would then no longer conform to the standard of the rim profile for which the tire has been designed.
Document U.S. Pat. No. 3,128,815 describes another insert in the form of a tire lining element intended to be engaged removably in a sidewall. This lining element may be fixed to the sidewall by various means, such as engagement of its ends in the sidewall, attachment at its ends by anchoring means that are raised or recessed in relation to the sidewall. Moreover, the lining element described covers a significant portion of the sidewall, typically at least one third of the surface area of the sidewall, and is positioned more particularly in the radially inner segment of the sidewall, between the axially outermost point of the sidewall and the rim flange. However, this lining element is liable to deform and become detached from the sidewall when the tire is running, because it is positioned in a zone of high deflection of the tire.
Document JPH11151918 also describes a removable colour insert intended to be fixed to a tire sidewall, in the radially outer segment of the sidewall, close to the tread, by virtue of an attachment means that is recessed in relation to the surface of the sidewall. However, such an attachment means does not make it possible to easily mount this insert on the tire when the tire is mounted on its rim and inflated, because the geometry of the insert there may be insufficient compared with the geometry of the recess of the attachment means, depending on the inflation pressure or depending on the width of the rim. In addition, when the tire is running, the locking of the insert in the sidewall can be modified, for example under strong transverse accelerations, with a risk of the insert being ejected.
The inventors set themselves the objective of proposing a tire that is able to be equipped with at least one sidewall insert, with improved mounting on and attachment to the sidewall.
This objective has been achieved by a tire for a lightweight vehicle, which tire is intended to be mounted on a rim and is able to be equipped with at least one sidewall insert, the said tire having a nominal section of height H and comprising:
The principle of the invention is to have an anchoring means, for a sidewall insert, which comprises a circumferential recess, formed in an axially outer sidewall layer, and a protuberance, formed in said recess.
The recess may be circumferentially continuous or circumferentially discontinuous, that is to say formed of separate circumferential portions.
The axially outer sidewall layer in which the recess is formed extends axially from an axially outer sidewall face, which is in contact with atmospheric air, to an axially outermost reinforcing layer, which is formed of reinforcers that are most often textile. More specifically, the axially outer sidewall layer is in axially inner contact with the rubber compound coating the reinforcers of the axially outermost reinforcing layer, usually referred to as coating compound.
The recess makes it possible to anchor the sidewall, by locking the edges of the sidewall insert between its walls. It thus contributes to holding the sidewall insert in place when the tire is running, said sidewall insert being liable to be ejected.
The recess also makes it possible to engage the sidewall insert in the thickness of the sidewall, so as to not create a significant protuberance in relation to the axially outer sidewall face, and therefore to not disrupt the flow of air in the vicinity of the sidewall in this zone. Consequently, the aerodynamic drag of the tire is not increased. Correspondingly, the rolling resistance of the tire, and therefore the fuel consumption, are also not increased.
According to the invention, the depth Pc of the recess is at least equal to 2 mm.
If the depth Pc is less than 2 mm, the anchoring means does not ensure sufficient attachment of the sidewall insert that makes it possible to withstand the various mechanical stresses applied to the tire in the course of its use, throughout its service life.
Likewise according to the invention, the width Lc of the recess is at most equal to 15% of the nominal section height H of the tire.
The width Lc of the recess must remain limited, because the more it increases, the more the deflection of the zone of the sidewall insert increases during use, this generating significant deformations and possible problems of fatigue of the sidewall insert. The deformations at the recess increase specifically with the width Lc of the recess, it being possible to express the width as a percentage of the nominal section height H of the tire or as an absolute value. The nominal section height H is defined by the usual standards relating to tires, such as, for example, the “European Tire and Rim Technical Organisation” or “ETRTO” standard.
The protuberance, formed in the recess from the recess bottom, is intended to come into contact with an axially inner face of the sidewall insert, and makes it possible to anchor the sidewall insert by virtue of its axially inner portion which has a minimum width Lpmin in the vicinity of the recess bottom. This protuberance configuration makes it possible to effectively clip the sidewall insert over the protuberance and ensures it is held in position when the tire is running, under mechanical bending and centrifugal stresses applied to the tire.
Advantageously, the depth Pc of the recess is at most equal to 3 mm.
More advantageously, the depth Pc of the recess is at most equal to 7 mm, and preferably at most equal to 5 mm.
If the depth Pc is greater than 7 mm, the thickness of the layer of rubber material, axially on the inside of the recess bottom, is not enough to ensure mechanical decoupling between the sidewall insert, which is intended to be engaged in the said recess, and the axially outermost reinforcing layer. This results in stress concentrations in the recess bottom that are liable to generate cracking and a reduction in the endurance of the sidewall. Furthermore, as regards manufacture, a recess of limited depth ensures the presence of a thickness of the layer of rubber material, axially on the inside of the recess bottom, despite the existence of significant movements of the materials present in this zone, during the steps for fabricating and then finishing the tire. In other words, a recess depth which is not too high makes it possible to ensure manufacturing tolerances.
With the axially outer sidewall layer having a width W at the anchoring means, the difference between the thickness W of the axially outer sidewall layer and the depth Pc of the recess is at least equal to 1 mm, preferably at least equal to 2 mm.
The thickness W is measured between the axially outer sidewall face and the axially outer fibres of the reinforcers of the axially outermost reinforcing layer: this thickness therefore takes into account the actual axially outer sidewall layer and the axially outer coating layer of the axially outermost reinforcing layer. The difference between the thickness W of the axially outer sidewall layer and the depth Pc of the recess thus defines the thickness of the layer of rubber material, comprised between the recess bottom and the axially outermost reinforcing layer.
A thickness of 1 mm is the minimum thickness of the layer of rubber material that ensures mechanical decoupling between the sidewall insert, which is intended to be engaged in the said recess, and the axially inner reinforcement of reinforcers at the interface with the axially outer sidewall layer. This minimum thickness consequently avoids stress concentrations in the recess bottom that are liable to generate cracking and a reduction in the endurance of the sidewall.
Advantageously, the width Lc of the recess is at most equal to 10% of the nominal section height H of the tire.
Likewise advantageously, the width Lc of the recess is at most equal to 20 mm, and preferably at most equal to 12 mm.
Preferably, the recess is formed in an axially outer sidewall layer made of a single rubber material.
Consequently, the recess is not formed in a composite layer, which is made up of a superposition of materials and therefore is potentially sensitive to problems of mechanical strength at the interfaces between the said materials.
Advantageously, the straight line, which is present in any meridian plane and passes through two intersection points respectively of each recess wall with the axially outer sidewall face, forms an angle at most equal to 25°, preferably at most equal to 15°, with the radial direction.
When the angle A is greater than 25°, the axially outer sidewall face becomes excessively inclined in relation to the radial direction, in the zone of the anchoring means, generally close to the tire bead. Consequently, the lateral walls of the recess do not make it possible to retain the sidewall insert, which will deform under the action of centrifugal forces.
Preferably, the protuberance has, in any meridian plane, a height Hp at least equal to the depth Pc of the recess less 2 mm.
A minimum height value Hp that is equal to the depth Pc of the recess less 2 mm makes it possible to position a sidewall insert over the protuberance, with a sufficient anchoring height whilst still not protruding beyond, or protruding only very little beyond, the axially outer sidewall face. This configuration thus ensures effective anchoring of the sidewall insert whilst still protecting it from potential scuffing of the sidewall against the kerb. Moreover, limited engagement of the sidewall insert in the thickness of the sidewall ensures it can be seen as design means.
Also preferably, the protuberance has, in any meridian plane, a height Hp at least equal to the depth Pc of the recess plus 2 mm.
A maximum height value Hp that is equal to the depth Pc of the recess plus 2 mm makes it possible to avoid the insert being raised in relation to the axially outer sidewall face. This configuration thus makes it possible to not disrupt the flow of air in the vicinity of the sidewall in this zone. Consequently, the aerodynamic drag of the tire is not increased. Correspondingly, the rolling resistance of the tire, and therefore the fuel consumption, are not increased. Moreover, sensitivity to potential scuffing of the sidewall against the kerb remains limited.
According to a preferred embodiment of the protuberance, the protuberance is constituted, in any meridian plane, by a stepped arrangement of a first narrow portion, extending axially towards the outside from the recess bottom and having a minimum width equal to the minimum protuberance width Lpmin, and a second wide portion, extending axially towards the outside from the first narrow portion and having a maximum width equal to the maximum protuberance width Lpmax. Such a protuberance thus has substantially the shape of a mushroom, the stem of which is the first narrow portion and the cap of which is the second wide portion.
With the sidewall comprising, on its axially outer sidewall face and in the radially outer vicinity of a bead, a protective ridge having an edge corner, and the anchoring means having a circumferential mean line, the circumferential mean line of the anchoring means is advantageously positioned, in any meridian plane, at a radial distance d1 at least equal to 4 mm, radially on the outside of the edge corner of the protective ridge.
A protective ridge is positioned on the axially outer sidewall face and in the radially outer vicinity of a bead. A positioning in the radially outer vicinity of the bead means that the radially innermost point of the protective ridge is positioned at a radial distance of at least 4 mm radially on the outside of a rim flange on which the tire is intended to be mounted. Furthermore, the edge corner of the protective ridge is the vertex of the substantially triangular section of the protective ridge, which is not located on the axially outer sidewall face.
Since the function of the protective ridge is to protect the flange of the rim on which the tire is intended to be mounted, it is the portion of the tire that is most liable to rub against external elements, such as kerbs and stones, and also the one that is most liable to come into contact with the ground when the tire is being dismounted. Consequently, the sidewall insert, and therefore the corresponding anchoring means, must be far enough away from the protective ridge to not be damaged. Furthermore, an anchoring means close to the protective ridge makes it even more visible.
Also advantageously, the circumferential mean line of the anchoring means is positioned, in any meridian plane, at a radial distance d2 at least equal to 10% of the nominal section height H of the tire, radially on the inside of an axial straight line passing through the halfway point H/2 of the nominal section height of the tire.
If, for certain tires having a small nominal section height H, and therefore a small sidewall height, the protective ridge is the axially outermost portion of the tire, for other tires the axially outermost point of the tire is positioned on an axial straight line passing through the halfway point H/2 of the nominal section height of the tire. For these tires, to avoid degradation of the sidewall insert, in particular when the sidewall scuffs against a kerb, the circumferential mean line of the corresponding anchoring means is advantageously radially positioned at a radial distance d2 at least equal to 10% of the nominal section height H of the tire, radially on the inside of the axial straight line passing through the halfway point H/2 of the nominal section height of the tire. Typically, the radial distance d2 is at least equal to 2 mm and preferably at least equal to 8 mm.
The invention also relates to a sidewall insert intended to be mounted on a tire sidewall.
The sidewall insert is intended to interact with an anchoring means according to any of the tire embodiments described above, by engaging in the recess (7) of the anchoring means (6) and by clipping over the protuberance (8) of the anchoring means (6).
The sidewall insert has a circumferential mean line having a mean diameter D2, before the sidewall insert is anchored to the tire, at most equal to a mean diameter D1 of a circumferential mean line of the anchoring means. In these conditions, the sidewall insert is anchored in the anchoring means under prestress, this contributing to effectively holding the sidewall insert in place in the sidewall, with a low risk of being ejected when the tire is running.
According to a particular embodiment, the sidewall insert may have a variable width in the vicinity of the axially outer sidewall face. This involves a variable width of the recess of the anchoring means, and therefore an anchoring means that does not exhibit symmetry of revolution about the axis of rotation of the tire.
According to a preferred embodiment, the sidewall insert comprises at least one polymeric material, such as a rubber material, a silicone or a thermoplastic material, for example a polyurethane.
The one or more materials of which the sidewall insert is made must be deformable enough not to generate excessive stresses at the interface between the sidewall insert and the anchoring means that are liable to induce cracking and fatigue ruptures in the sidewall of the tire. A polymeric material, such as a rubber material, a silicone or a thermoplastic material, for example a polyurethane, this list not being exhaustive, would meet this requirement.
With the sidewall insert being made of a material having a tensile elastic modulus at 10% elongation M2 and being intended to interact with an anchoring means made of a rubber material having a tensile elastic modulus at 10% elongation M1, M2 is advantageously at least equal to 0.4*M1. The sidewall insert must be stiff enough to enable it to be installed on the sidewall.
With the sidewall insert being made of a material having a tensile elastic modulus at 10% elongation M2 and being intended to interact with an anchoring means made of a rubber material having a tensile elastic modulus at 10% elongation M1, M2 is also advantageously at most equal to 5*M1. The sidewall insert must not be too stiff, so as to not generate excessive stresses in the sidewall of the tire that are liable to damage the sidewall when it is subjected to bending stresses, and to reduce the risk of the sidewall insert being ejected by centrifugation when the tire is running.
The sidewall insert preferably has a colouration and/or a texture different from those of the sidewall comprising the anchoring means. Since the objective of the invention is to personalize the design of the tire sidewalls, the sidewall insert preferably has a differentiating colouration and/or a texture in relation to the sidewall.
The preferably coloured sidewall insert may have one or more differentiated colours in relation to the usually black colour of the sidewall. Also preferably, the sidewall insert is monochrome, with the aim of simplifying its manufacture.
According to particular embodiment variants, to further differentiate the sidewall, the sidewall insert is covered with a graphic or a texture, for example of velvet type.
Lastly, the invention relates to an assembly made up of a tire according to any one of the embodiments of the tire that were described above, and at least one sidewall insert according to any one of the embodiments of the sidewall insert that were described above.
The features of the invention are illustrated by the schematic
The inventors have more particularly examined this invention for a tire of size 245/45 R 18 100 W XL, which is intended to be inflated to a recommended pressure equal to 2.9 bar and to bear a recommended load equal to 800 kg.
The characteristics of the example examined by the inventors are presented in Table 1 below:
The inventors were able to note facilitated mounting and more effective attachment for a sidewall insert with which a sidewall of the tire according to the invention is equipped.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR2010023 | Oct 2020 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2021/051675 | 9/28/2021 | WO |
