FR3159347A1 - Pneumatic comprising a durable stiffening structure and a high-performance radially internal anchorage - Google Patents

Abstract

The tire (10) comprises sidewalls (30A, 30B), beads (32A, 32B), a radially inner reinforcing structure (38A) arranged in a sidewall (30A) and/or bead (32A), a circumferential anchoring element (42A) extending in the sidewall (30A) and/or bead (32A) from a radially outer end (421A) to a radially inner end (422A), a stiffening structure (52) comprising a radially inner anchoring portion (541) extending in the sidewall (30A) and/or bead (32A) from a radially inner anchoring point (56A) to be anchored in or around a radially inner reinforcing structure (38A). The radially inner anchoring portion (541) extends from the radially inner reinforcing structure (38A) radially inwardly outside an area arranged radially between the radially outer (421A) and inner (422A) ends and axially between the circumferential attachment element (42A) and a carcass layer (50). Figure for abstract: Fig 1

Description

Pneumatic comprising a durable stiffening structure and a high-performance radially internal anchorage

The present invention relates to a tire, in particular for a passenger vehicle.

A tire is understood to mean a bandage intended to form a cavity by cooperating with a mounting support, for example a rim, this cavity being capable of being pressurized to a pressure higher than atmospheric pressure. A tire has a structure of substantially toroidal shape of revolution around a main axis of the tire, this main axis being the same as the axis of rotation of the tire.

Previous techniques

Known from the state of the art is a tire intended to equip a passenger vehicle and described in WO2020/128225. The tire described comprises a crown extended radially inwards respectively on each side of the median plane of the tire by first and second sidewalls then by first and second beads intended to come into contact with a mounting support, for example a rim. Each first and second bead comprises a circumferential reinforcing element intended to allow the tire to be attached to the mounting support.

The tire includes an internal surface delimiting a toric cavity for inflating the tire once the latter is mounted on the mounting support.

The tire described in WO2020/128225 comprises a stiffening structure comprising first stiffening elements extending continuously in the toric cavity from the first bead to the crown and second stiffening elements extending continuously in the toric cavity from the second bead to the crown.

Each first and second stiffening element is secured to each bead from which it extends by a bead interface between the stiffening element and a portion of the inner surface of the bead. Similarly, each first and second stiffening element is secured to the crown of the tire by a crown interface between the stiffening element and a portion of the inner surface of the crown. Each bead and crown interface comprises a cushion of elastomeric mixture positioned between the stiffening element and the portion of the corresponding inner surface.

It was noted that each bead and crown interface was subjected to tensile stress. Such interfaces are sensitive to repeated stresses which can lead to early debonding between the stiffening elements and the inner surface of the bead and/or the inner surface and therefore to early destruction of the stiffening structure.

The endurance of the tire described in WO2020/128225 was improved in WO2022/200717 by using an anchoring of each first and second stiffening element in the internal structure of the tire. However, the endurance of the tire described in WO2022/200717, in particular the endurance of the anchoring of the first and second stiffening elements in each first sidewall and/or bead and second sidewall and/or bead, although significantly improved compared to that of the tire described in WO2020/128225, proved to be improvable. Indeed, it was noted that the stiffening structure was degrading due to the loosening of the stiffening elements in one of the first and second beads.

The aim of the invention is to improve the endurance of the stiffening structure described in WO2020/128225 and to ensure the integrity of the tire even in the event of the tire stiffening elements described in WO2022/200717 becoming loose.

The invention relates to a tire comprising a crown, first and second sidewalls each extending the crown radially inwards, first and second beads respectively extending the first and second sidewalls radially inwards, the tire being provided with an internal surface delimiting a toric inflation cavity of the tire, the tire having a substantially toric shape around an axis of revolution and comprising:

- at least one first radially internal reinforcing structure arranged in the first sidewall and/or bead,

- a stiffening structure comprising at least one first stiffening element extending continuously in the toric cavity from at least the first flank and/or bead to at least the top, and comprising at least one radially inner anchoring portion extending in the first flank and/or bead from a radially inner anchoring point of said first stiffening element to be anchored in or around said first radially inner reinforcing structure,

- at least one first circumferential attachment element intended to allow the tire to be attached to a mounting support, and extending in the first sidewall and/or bead radially inward from a radially outer end to a radially inner end of said first circumferential attachment element, said radially inner anchoring portion of said first stiffening element extending, from said first radially inner reinforcing structure, radially inward at least partly along said first circumferential attachment element, said first circumferential attachment element being axially adjacent to said radially inner anchoring portion,

- a carcass reinforcement comprising at least one carcass layer arranged at least in the first sidewall and/or bead and extending radially along said first circumferential attachment element, said first circumferential attachment element being axially adjacent to the carcass layer,

tire in which said radially inner anchoring portion of said first stiffening element extends outside an area located:

- axially between said carcass layer and said first circumferential attachment element, and

- radially between the radially outer end and the radially inner end of said first circumferential attachment element.

As explained below, the invention works as soon as it is applied to only one side of the tire, here at least on the side comprising the first sidewall and/or bead. Advantageous embodiments teach to also apply the invention to both sides of the tire without this being necessary to carry out the invention. Thus, in the present application, the use of the qualifier “first” or “first” aims, unless there is an obvious different interpretation, to associate the element qualified as “first” or “first” with the first sidewall and/or bead. Similarly, the use of the qualifier “second” aims, unless there is an obvious different interpretation, to associate the element qualified as “second” with the second sidewall and/or bead.

Advantageously, the first sidewall and/or bead is arranged on the same side of the median plane of the tire as the outer side of the tire. Thus, the stiffening structure acts on the side of the tire that is most stressed during high drift stresses. By inner and outer sides, we mean that the tire is designed so that one of its sides is arranged on the inner side and the other of its sides is arranged on the outer side. This orientation imposed by the tire manufacturer ensures that the tire has the expected operation. Indeed, mounting a tire with an orientation different from that imposed by the manufacturer can lead to suboptimal behavior of the vehicle. By outer side, we mean the side of the tire that is entirely visible from the outside of the vehicle when the tire is mounted on the vehicle. By inner side, we mean the side of the tire facing the wheel arch of the vehicle on which it is mounted. Generally, the tire has a marking indicating the inner side and the outer side.

In a preferred embodiment in which the stiffening structure performs its function on either side of the median plane of the tire, which makes it possible to obtain homogeneous behavior of the tire, the tire comprises:

- at least one second radially internal reinforcing structure arranged in the second sidewall and/or bead,

- the stiffening structure comprising at least one second stiffening element extending continuously in the toric cavity from at least the second flank and/or bead to at least the top, and comprising at least one radially inner anchoring portion extending in the second flank and/or bead from a radially inner anchoring point of said second stiffening element to be anchored in or around said second radially inner reinforcing structure,

- at least one second circumferential attachment element intended to allow the tire to be attached to a mounting support, and extending in the second sidewall and/or bead radially inward from a radially outer end to a radially inner end of said second circumferential attachment element, said radially inner anchoring portion of said second stiffening element extending, from said second radially inner reinforcing structure, radially inward at least partly along said second circumferential attachment element, said first circumferential attachment element being axially adjacent to said radially inner anchoring portion,

- said carcass layer being arranged at least in the second sidewall and/or bead and extending radially along said second circumferential attachment element, said second circumferential attachment element being axially adjacent to the carcass layer,

tire in which said radially inner anchoring portion of said second stiffening element extends outside an area located:

- axially between said carcass layer and said second circumferential attachment element, and

- radially between the radially outer end and the radially inner end of said second circumferential attachment element.

The stiffening element concerned exerts high forces on the corresponding sidewall and/or bead which are absorbed by said corresponding radially inner reinforcement structure. These high forces are the cause, in the tire of the state of the art described in WO2022/200717, of the initiation of cracks at the anchorage in the sidewall and/or bead. When the radially innermost point of the stiffening element concerned is arranged radially outside the radially outer end of the circumferential attachment element or, even worse, when the radially innermost point of the stiffening element concerned is arranged axially between the carcass layer and the circumferential attachment element, the cracks can propagate in the area located axially between the carcass layer and the corresponding circumferential attachment element and located radially between the radially outer end and the radially inner end of the circumferential attachment element concerned and lead to the separation of the circumferential attachment element.

The positioning of the radially inner anchoring portion concerned according to the invention at least partly along the circumferential attachment element, that is to say radially inside the radially outer end of the circumferential attachment element while remaining outside the zone situated axially between the carcass layer and the circumferential attachment element and situated radially between the radially outer end and the radially inner end of the circumferential attachment element, makes it possible to ensure the integrity of the tire even if crack initiation and propagation were to occur, nevertheless causing the loss of the advantages associated with the stiffening structure. On the contrary, a crack initiated in said zone may lead, in addition to the loss of the advantages associated with the stiffening structure, to degradation of the structure of the tire, for example by uncontrolled crack propagation leading to separation of the circumferential attachment element.

Thus, an anchorage according to the invention is significantly more robust than the bead interfaces described in WO2020/128225 and ensures the integrity of the tire compared to WO2022/200717.

The radially outer end of the circumferential attachment element corresponds to the point of said circumferential attachment element located most radially to the outside. Similarly, the radially inner end of the circumferential attachment element corresponds to the point of said circumferential attachment element located most radially to the inside.

The carcass reinforcement may comprise several carcass layers. The invention may therefore be preferentially applied to each carcass layer of the carcass reinforcement.

A circumferential gripping element is axially adjacent to the carcass layer means that the circumferential gripping element is the circumferential element axially closest to the carcass layer when moving axially inward or outward from the carcass layer. Thus, a carcass layer may have a single circumferential gripping element adjacent axially inward or axially outward or two circumferential gripping elements adjacent axially inward and axially outward.

A circumferential anchoring element is axially adjacent to the radially inner anchoring portion means that the circumferential anchoring element is the circumferential element axially closest to the radially inner anchoring portion.

In some cases, the circumferential attachment element is in contact with the carcass layer so that the area located axially between the carcass layer and the circumferential attachment element and located radially between the radially outer end and the radially inner end of the circumferential attachment element has a thickness that is substantially zero over all or part of the length of the circumferential attachment element. In other more preferred cases, the circumferential attachment element is at a distance from the carcass layer so that the zone located axially between the carcass layer and the circumferential attachment element and located radially between the radially outer end and the radially inner end of the circumferential attachment element has a non-zero thickness, preferably less than or equal to 1 mm and for example equal to 0.5 mm, so as to ensure mechanical decoupling between the carcass layer and the circumferential attachment element.

In some cases, the radially inner anchoring portion extends along the circumferential attachment element in contact with the circumferential attachment element. In other preferred cases, the radially inner anchoring portion extends along the circumferential attachment element at a distance from the circumferential attachment element, preferably at a distance less than or equal to 1 mm and for example equal to 0.5 mm, so as to reduce as much as possible the risk of propagation of a possible crack initiation from the radially inner anchoring portion axially through the circumferential attachment element.

The radially inner reinforcing structure arranged radially outside the corresponding circumferential attachment element makes it possible to reduce the propagation of noise generated by the stiffening structure from the stiffening structure to the vehicle through the tire mounting bracket. Indeed, the noise generated by the stiffening structure is damped by the tire structure separating the radially inner reinforcing structure in question from the circumferential attachment element located on the same side of the tire median plane.

This damping is the result of the fact that the radially inner reinforcement structure considered is mechanically decoupled from the circumferential attachment element located on the same side of the median plane of the tire.

The toric inflation cavity is intended to be pressurized by an inflation gas once the tire is mounted on a mounting support, most often a rim.

Among other advantages, the stiffening structure makes it possible to simultaneously increase the radial stiffness, axial stiffness and drift stiffness of the tire compared to a conventional tire not comprising a stiffening structure but also compared to tires comprising other stiffening structures, such as that described in WO2017/005713.

By increasing the radial rigidity, the stiffening structure limits the radial deformation of the crown, during rolling, and in particular, the counter-deflection, that is to say the radial deformation, opposite the contact area of the rolling surface in contact with the ground. Thus, during the rolling of the tire, during the wheel revolution, the stiffening structure makes it possible to limit the amplitude of the cyclic deformations of the tire, and in particular of its tread, and therefore to limit the resulting energy dissipation, which contributes to the reduction of the rolling resistance. In addition, under radial stress, the value of the contact area with the ground is not modified, which makes it possible to maintain the same grip performance as for the tire described in WO2017/005713.

By increasing axial stiffness and drift stiffness, the stiffening structure will contribute to improving behavior under transverse stress, for example when drifting. In addition, under transverse stress, the contact area with the ground ensures a more homogeneous distribution of contact pressures, which increases transverse grip.

Furthermore, the stiffening structure participates at least partially in carrying the load applied to the tire such that this applied load is taken up jointly by the tire, thanks to its pneumatic rigidity and its intrinsic structural rigidity and by the stiffening structure. Thus, when the tire is subjected to a nominal radial load, a portion of the stiffening structure arranged opposite the contact area is put under tension. In certain embodiments, conversely, a portion of the stiffening structure arranged opposite the contact area is subjected to compression buckling.

The presence of the stiffening structure thus makes it possible to reduce the tire's contribution to carrying the load and therefore to be able to reduce its structural rigidity, for example by reducing the volume of the beads. Indeed, the beads of a conventional tire dissipate a significant quantity of energy, due to their volume and the hysteretic nature of their constituent elastomeric mixture. Reducing their volume thus makes it possible to significantly reduce rolling resistance.

The tire according to the invention has a substantially toric shape around an axis of revolution substantially coincident with the axis of rotation of the tire. This axis of revolution defines three directions conventionally used by those skilled in the art: an axial direction, a circumferential direction and a radial direction.

Axial direction means the direction substantially parallel to the axis of revolution of the tire, i.e. the axis of rotation of the tire.

Circumferential direction means the direction which is substantially perpendicular to both the axial direction and a radius of the tire (in other words, tangent to a circle whose center is on the axis of rotation of the tire).

By radial direction is meant the direction along a radius of the tire, that is to say any direction intersecting the axis of rotation of the tire and substantially perpendicular to this axis.

By median plane of the tire, noted M, we mean the plane perpendicular to the axis of rotation of the tire which is located at the axial mid-distance of the two beads and passes through the axial center of the crown reinforcement.

By equatorial circumferential plane of the tire, noted E, is meant, in a meridian section plane, the plane passing through the equator of the tire, perpendicular to the median plane and to the radial direction. The equator of the tire is, in a meridian section plane (plane perpendicular to the circumferential direction and parallel to the radial and axial directions) the axis parallel to the axis of rotation of the tire and located equidistant between the radially outermost point of the tread intended to be in contact with the ground and the radially innermost point of the tire intended to be in contact with a support, for example a rim.

By meridian plane is meant a plane parallel to and containing the axis of rotation of the tire and perpendicular to the circumferential direction.

By radially inner, respectively radially outer, we mean closer to the tire's axis of rotation, respectively further from the tire's axis of rotation. By axially inner, respectively axially outer, we mean closer to the tire's median plane, respectively further from the tire's median plane.

By bead is meant the radial portion of the tire intended to allow the tire to be attached to a mounting support, for example a wheel comprising a rim. Thus, each bead is in particular intended to be in contact with a hook on the rim allowing it to be attached. The bead is thus delimited radially internally by the radially inner end of the tire and radially externally by an axial line passing through the radially outermost point in contact with a standard rim within the meaning of the European Tire and Rim Technical Organization or “ETRTO” standard, 2023.

The sidewall is the radial portion of the tire connecting the bead to the crown. The sidewall is delimited radially externally by a tread edge. The axial edges of the tread are determined on a tire mounted on a nominal rim and inflated to the nominal pressure as defined in the ETRTO 2023 standard manual. The edges are arranged on either side of the median plane of the tire and formed by lines substantially parallel to the circumferential direction of the tire. In the case of an obvious boundary between the tread and the sidewall of the tire, the edges are determined simply. In the case where the tread is continuous with the sidewalls, the edges are usually determined by loading the tire to 80% of its load capacity according to the ETRTO 2023 standard manual and the edges are identified as the axial limits of the tread in contact with the ground. The sidewall is delimited radially internally by an axial line passing through the radially outermost point in contact with a standard rim within the meaning of the European Tyre and Rim Technical Organisation or “ETRTO” standard, 2023.

Any interval of values designated by the expression "between a and b" represents the domain of values from more than a to less than b (i.e., excluding the limits a and b), while any interval of values designated by the expression "from a to b" means the domain of values from a to b (i.e., including the strict limits a and b).

The tires of the invention are preferably intended for passenger vehicles as defined in the sense of the standard of the European Tyre and Rim Technical Organisation or “ETRTO”, 2023. Such a tire has a section in a meridian cutting plane characterized by a section height H and a nominal section width SW in the sense of the standard of the European Tyre and Rim Technical Organisation or “ETRTO”, 2023. The values of SW and H are indicated on the marking of the sidewall of the tire, for example as defined according to the ETRTO manual, 2023.

Preferably, the passenger vehicle tires to which the invention will advantageously be applied are such that the H/S ratio, expressed as a percentage, is at most equal to 90 and at least equal to 20, and the nominal section width SW is at least equal to 115 mm and at most equal to 385 mm. In addition, the hook diameter D, defining the diameter of the rim on which the tire is mounted, is at least equal to 12 inches and at most equal to 30 inches.

Optionally, the first circumferential attachment element is arranged radially inside said first radially inner reinforcing structure by being wound circumferentially around the axis of revolution.

Optionally, the second circumferential attachment element is arranged radially inside said second radially inner reinforcement structure by being wound circumferentially around the axis of revolution.

Optionally, said first circumferential attachment element is wound circumferentially over at least two complete turns, preferably over at least three complete turns, more preferably over at least four complete turns, even more preferably over at least five complete turns and very preferably over at least six complete turns, around the axis of revolution.

Optionally, said second circumferential attachment element is wound circumferentially over at least two complete turns, preferably over at least three complete turns, more preferably over at least four complete turns, even more preferably over at least five complete turns and very preferably over at least six complete turns, around the axis of revolution.

In one embodiment, said first and/or second circumferential attachment element is a wire reinforcement element extending in a main direction forming with the circumferential direction of the tire an angle less than or equal to 10°, preferably less than or equal to 5° and more preferably substantially zero.

The first radially internal reinforcement structure arranged in the first sidewall and/or bead preferably comprises at least one first radially internal circumferential reinforcement element allowing the anchoring of the stiffening structure.

In the embodiments comprising a second radially internal reinforcement structure arranged in the second sidewall and/or bead, this preferably comprises at least one second radially internal circumferential reinforcement element allowing the anchoring of the stiffening structure.

In one embodiment, the first and/or second radially inner reinforcement structure comprises at least one wire reinforcement element extending in a main direction forming with the circumferential direction of the tire an angle less than or equal to 10°, preferably less than or equal to 5° and more preferably substantially zero.

In a particular embodiment, the first and/or second radially inner reinforcing structure comprises at least two distinct wire reinforcing elements.

By distinct, we mean that the two wire reinforcement elements are discontinuous with respect to each other.

Advantageously, the or each wire reinforcement element of the first and/or second radially inner reinforcement structure is wound circumferentially over at least one complete turn around the axis of revolution.

Advantageously, said first stiffening element penetrates the top at a first radially outer anchoring point of said first stiffening element.

Optionally, said second stiffening element penetrates the vertex at a second radially outer anchoring point of said second stiffening element.

Advantageously, said first stiffening element comprises a portion extending continuously in the toric cavity from the first radially inner anchoring point to the first radially outer anchoring point.

Advantageously, said first stiffening element comprises a radially outer anchoring portion extending from the first radially outer anchoring point in the crown and extending the portion extending continuously in the toric cavity.

Optionally, said second stiffening element comprises a portion extending continuously in the toric cavity from the second radially inner anchoring point to the second radially outer anchoring point.

Optionally, said second stiffening element comprises a radially outer anchoring portion extending from the second radially outer anchoring point in the apex and extending the portion extending continuously into the toric cavity.

Advantageously, said radially outer anchoring portion of said first stiffening element is anchored in the crown by being anchored in or around one or more radially outer reinforcing structures of the stiffening structure arranged in the crown.

Alternatively, said radially outer anchoring portion of said first stiffening element is anchored in the crown by being anchored in an elastomeric mass of said crown.

Optionally, said radially outer anchoring portion of said second stiffening element is anchored in the crown by being anchored in or around one or more radially outer reinforcing structures of the stiffening structure arranged in the crown.

Alternatively, said radially outer anchoring portion of said second stiffening element is anchored in the crown by being anchored in an elastomeric mass of said crown.

Each radially inner or outer reinforcing structure is respectively arranged in the corresponding flank and/or bead or in the crown, that is to say arranged radially inside the internal surface and embedded in the mass of materials constituting the corresponding flank and/or bead or the crown. The stiffening structure passes through the internal surface to be anchored in or around the corresponding radially inner reinforcing structure and/or through the internal surface to be anchored in or around the or one of the radially outer reinforcing structure(s).

As previously indicated, the stiffening structure may be anchored in or around at least one radially inner and/or outer reinforcing structure.

Thus, in a first variant, the stiffening structure can be anchored in the very structure of said reinforcing structure, that is to say that the stiffening structure penetrates at least partly into said reinforcing structure, or even passes through it completely so that said reinforcing structure forms a mechanical anchoring of the stiffening structure.

In particular, in the case where said reinforcing structure is an assembly of several wire elements, the stiffening structure is “anchored in the structure” means, for example, that the stiffening structure wraps around certain wire elements of said reinforcing structure so as to pass through it.

In a second variant, the stiffening structure can be anchored around the very structure of said reinforcing structure, that is to say that the stiffening structure rests on said reinforcing structure so that said reinforcing structure takes up part of the forces exerted on the stiffening structure and anchors the stiffening structure in the sidewall and/or the bead or the crown.

In particular, in the case where said reinforcing structure is an assembly of several wire elements, the stiffening structure is “anchored around the structure” means, for example, that the stiffening structure wraps around the peripheral wire elements of said reinforcing structure without passing through it.

In the embodiments comprising at least one radially outer reinforcing structure arranged in the crown, the latter preferably comprises at least one radially outer circumferential reinforcing element.

In one embodiment, said radially outer circumferential reinforcing element of the or each radially outer reinforcing structure is a wire reinforcing element extending in a main direction forming with the circumferential direction of the tire an angle less than or equal to 10°, preferably less than or equal to 5° and more preferably substantially zero.

In some embodiments, the tire comprises first and second radially outer reinforcing structures. In these embodiments, preferably, each first and second radially outer reinforcing structure respectively comprises a first and second radially outer circumferential reinforcing element, the first radially outer circumferential reinforcing element being arranged axially spaced from said second radially outer circumferential reinforcing element.

This reduces the mass of the reinforcement structure allowing the anchoring of the stiffening structure in the crown and limits the over-frettage of the crown, thus maintaining a regular contact area.

Preferably, the first radially outer circumferential reinforcing element and the second radially outer circumferential reinforcing element are arranged on either side of the median plane of the tire.

This improves the axial distribution of the forces exerted by the stiffening structure on the top.

In other embodiments, the tire comprises a single radially outer reinforcement structure extending continuously on each side of the median plane of the tire. Conventionally, in a tire comprising a crown reinforcement and a carcass reinforcement, the crown comprises a tread intended to come into contact with the rolling ground and a crown reinforcement arranged radially inside the tread. The carcass reinforcement is anchored in each bead and extends radially in each sidewall and axially in the crown radially inside the crown reinforcement. Conventionally, the crown reinforcement comprises at least one crown layer comprising reinforcing elements. These reinforcing elements are preferably textile or metal wire elements.

In embodiments allowing the performance of so-called radial tires to be obtained as defined by the ETRTO, the carcass reinforcement comprises at least one carcass layer, said carcass layer comprising carcass cord reinforcement elements, each carcass cord reinforcement element extending substantially in a main direction forming with the circumferential direction of the tire, an angle, in absolute value, ranging from 80° to 90°. As a variant, it will be possible to have a variable angle ranging from 80° to 90° in at least one part of the sidewall and strictly less than 80° in at least one part of the crown.

In an advantageous embodiment, the stiffening structure is not sealed against a tire inflation gas. Thus, the stiffening structure allows the inflation gas to pass through. In other words, the stiffening structure does not delimit a secondary cavity under pressure in the tire. By "not sealed", it is understood that the stiffening structure is permeable to the inflation gas so that the pressure is uniform in the toric cavity at all times and, in particular, during tire inflation.

In advantageous embodiments, said radially inner anchoring portion of said first stiffening element extends radially inward to a point arranged radially inside the radially outer end of said first circumferential attachment element.

In embodiments using a second stiffening element, said radially inner anchoring portion of said second stiffening element extends radially inward to a point arranged radially inside the radially outer end of said second circumferential attachment element.

Thus, the anchoring portion concerned extends radially relatively deeply into the corresponding flank and/or bead, which improves the endurance of the anchoring of the stiffening structure.

In a variant, said radially inner anchoring portion of said first stiffening element extends radially inward to a point arranged radially outside the radially inner end of said first circumferential attachment element.

In embodiments using a second stiffening element, said radially inner anchoring portion of said second stiffening element extends radially inward to a point arranged radially outward of the radially inner end of said second circumferential attachment element.

In this variant, the amount of the stiffening portion extending radially inwards is optimized. In addition, the risk of damaging the integrity of the tire is further delayed by the relatively large radial height of materials radially inside the radially inner anchoring portion which must be crossed in the event of crack initiation.

In another variant, said radially inner anchoring portion of said first stiffening element extends radially inward to a point arranged radially inside the radially inner end of said first circumferential attachment element.

In embodiments using a second stiffening element, said radially inner anchoring portion of said second stiffening element extends radially inward to a point arranged radially inside the radially inner end of said second circumferential attachment element.

Optionally, said radially inner anchoring portion of said first stiffening element extends radially inward at least from the radially outer end of said first circumferential attachment element over at least 10%, preferably at least 20% of a length of said first circumferential attachment element.

In embodiments using a second stiffening element, said radially inner anchoring portion of said second stiffening element extends radially inward at least from the radially outer end of said second circumferential attachment element over at least 10%, preferably at least 20% of a length of said second circumferential attachment element.

Thus, the anchoring portion has a relatively long length to improve the endurance of the anchoring of the stiffening structure. Indeed, too short a length of the radially inner anchoring portion from the radially outer end of the first circumferential element would make the anchoring of the stiffening structure sensitive to its loosening during heavy stresses.

The length of the circumferential attachment element is taken between the radially outer and inner ends and is the distance of the straight line segment joining the radially outer and inner ends of said circumferential attachment element.

The length of the radially inner anchoring portion from the radially outer end of the corresponding circumferential attachment element is the distance of the straight line segment joining the point of the radially inner anchoring portion at the radially outer end of the circumferential attachment element and the most radially inner point of the radially inner anchoring portion.

Thus, the ratio between the length of the radially inner anchoring portion and the length of the circumferential attachment element corresponds to the overlap length ratio of these two lengths.

Optionally, said radially inner anchoring portion of said first stiffening element comprises at least first and second branches, said first branch extending radially inward and axially outward from the radially inner anchoring point of said first stiffening element, said second branch extending radially inward and axially inward from said first branch or from a third branch of said first stiffening element connecting said first branch and said second branch.

In embodiments using a second stiffening element, said radially inner anchoring portion of said second stiffening element comprises at least first and second branches, said first branch extending radially inward and axially outward from the radially inner anchoring point of said second stiffening element, said second branch extending radially inward and axially inward from said first branch or from a third branch of said second stiffening element connecting said first branch and said second branch.

The first and second branches thus arranged make it possible to create a robust anchoring of the anchoring portion due to the change in the direction in which the anchoring portion extends in the axial direction.

In advantageous embodiments, the second branch extends radially at least in part along said first circumferential attachment element. Thus, the second branch extends radially at least in part inside the radially outer end of said first circumferential attachment element.

In embodiments using a second stiffening element, the second branch extends radially at least in part along said second circumferential attachment element. Thus, the second branch extends radially at least in part inside the radially outer end of said second circumferential attachment element.

Thus, the second branch participates in the anchoring of the stiffening element concerned, all the more so since it extends radially inside the radially outer end of the circumferential attachment element adjacent to said radially inner anchoring portion concerned.

In a preferred configuration, said radially inner anchoring portion of said first stiffening element extends radially inward at least partly along said first circumferential attachment element without being anchored in the first circumferential attachment element.

In a preferred configuration, said radially inner anchoring portion of said second stiffening element extends radially inward at least partly along said second circumferential attachment element without being anchored in the second circumferential attachment element.

This further reduces the risk that the significant stresses exerted on the stiffening element will cause the circumferential attachment element to separate.

In another configuration, said radially inner anchoring portion of said first stiffening element extends radially inwardly at least partially along said first circumferential attachment element while being anchored in or around said first circumferential attachment element.

In embodiments using a second stiffening element, said radially inner anchoring portion of said second stiffening element extends radially inwardly at least partially along said second circumferential gripping element while being anchored in or around said second circumferential gripping element.

Optionally, the tire comprises a first axially inner circumferential attachment element and a first axially outer circumferential attachment element intended to allow the tire to be attached to a mounting support, and arranged radially inside said first radially inner reinforcing structure, each first axially inner and outer circumferential attachment element being axially adjacent to the carcass layer and extending in the first sidewall and/or bead radially inward from a radially outer end to a radially inner end respectively of said first axially inner and outer circumferential attachment element, said carcass layer extending radially along each first axially inner and outer circumferential attachment element and axially between said first axially inner circumferential attachment element and said first axially outer circumferential attachment element.

Thus, the carcass layer is anchored in the first sidewall and/or bead between said first axially inner circumferential attachment element and said first outer circumferential attachment element.

Optionally, the tire comprises a second axially inner circumferential attachment element and a second axially outer circumferential attachment element intended to allow the tire to be attached to a mounting support, and arranged radially inside said second radially inner reinforcing structure, each second axially inner and outer circumferential attachment element being axially adjacent to the carcass layer and extending in the second sidewall and/or bead radially inward from a radially outer end to a radially inner end respectively of said second axially inner and outer circumferential attachment element, said carcass layer extending radially along each second axially inner and outer circumferential attachment element and axially between said second axially inner circumferential attachment element and said second axially outer circumferential attachment element.

Thus, the carcass layer is anchored in the second sidewall and/or bead between said second axially inner circumferential attachment element and said second axially outer circumferential attachment element.

In one configuration, said radially inner anchoring portion of said first stiffening element extends at least partly axially inside said first axially inner circumferential attachment element.

In embodiments using a second stiffening element, said radially inner anchoring portion of said second stiffening element extends at least partly axially inside said second axially inner circumferential attachment element.

In this configuration, the tire manufacturing process is simplified by keeping the radially inner anchoring portion axially inside the carcass layer.

In this configuration, the optional and advantageous characteristics previously described with reference to the first and/or second circumferential attachment element can be applied optionally and advantageously to the first and/or second axially inner circumferential attachment element.

In another configuration, said radially inner anchoring portion of said first stiffening element axially passes through said carcass layer and extends at least partly axially outside said first axially outer circumferential attachment element.

In embodiments using a second stiffening element, said radially inner anchoring portion of said second stiffening element axially passes through said carcass layer and extends at least partly axially outside said second axially outer circumferential attachment element.

In this other configuration, the tire manufacturing process is complicated by moving the radially inner anchoring portion axially outside the carcass layer, but the anchoring of this radially inner anchoring portion is made more robust by increasing its length.

In this other configuration, the optional and advantageous characteristics previously described with reference to the first and/or second circumferential attachment element can be applied optionally and advantageously to the first and/or second axially external circumferential attachment element.

In optional embodiments, said first radially inner reinforcing structure comprises a first radially inner circumferential reinforcing element distinct from the first circumferential attachment element.

Preferably, in configurations using first axially inner and outer circumferential attachment elements, the first radially inner circumferential reinforcement element of said first radially inner reinforcement structure is distinct from each first axially inner and outer circumferential attachment element.

In embodiments using a second stiffening element, said second radially inner reinforcing structure comprises a second radially inner circumferential reinforcing element distinct from the second circumferential attachment element.

Preferably, in configurations using second axially inner and outer circumferential attachment elements, the second radially inner circumferential reinforcement element of said second radially inner reinforcement structure is distinct from each second axially inner and outer circumferential attachment element.

This mechanically disconnects the anchoring of the stiffening structure from the attachment of the tire to its mounting support.

By distinct, we mean that the circumferential elements are discontinuous with respect to one another or to each other.

Advantageously, said first radially inner anchoring point of said first stiffening element and said first radially outer anchoring point of said first stiffening element are arranged on the same side of the median plane of the tire.

Optionally, said second radially inner anchoring point of said second stiffening element and said second radially outer anchoring point of said second stiffening element are arranged on the same other side of the median plane of the tire.

Thus, the portions extending on the one hand, between a radially inner anchoring point and a radially outer anchoring point located on the same side of the median plane and on the other hand, between a radially inner anchoring point and a radially outer anchoring point located on the other side of the median plane, do not cross, which makes it possible to limit the axial buckling of the tread, i.e. the axial compression of the tread, in particular under conditions of high lateral stresses. Thus, on the one hand, a regular contact area is maintained, and on the other hand, the risk of deterioration of the crown reinforcement of the tire is reduced, in particular by avoiding the compression of the various constituent elements of the crown reinforcement, for example the textile and metal wire reinforcement elements of the crown reinforcement.

Preferably, the stiffening structure comprises a plurality of first stiffening elements distributed circumferentially in the toric cavity.

Optionally, the stiffening structure comprises a plurality of second stiffening elements distributed circumferentially in the toric cavity.

In a first configuration of the stiffening elements, each first stiffening element forms a first continuous stiffening element that winds at least from the first sidewall and/or bead through the apex. Also preferably, each second stiffening element forms a second continuous stiffening element that winds at least from the second sidewall and/or bead through the apex.

Thus, the manufacture of the tire is facilitated and the robustness of the stiffening structure is improved by removing ends of said stiffening element to be anchored in each sidewall and/or bead and/or in the crown. In this first configuration, it is thus possible to have a continuous stiffening element extending over the entire circumference of the tire. Said stiffening element of the stiffening structure being continuous, the transmission of forces between each sidewall and/or bead is improved, the transmission of forces being thus distributed over the tire. Thus, the stiffening structure performs its function over the entire circumference of the tire.

According to a first variant of the first configuration of the stiffening elements, said first and second stiffening elements form a continuous stiffening element which extends continuously from the first flank and/or bead towards the second flank and/or bead via the top so as to snake from the first flank and/or bead to the second flank and/or bead.

According to a second variant of the first configuration of the stiffening elements, each first stiffening element forms a continuous stiffening element which winds between the first sidewall and/or bead and the crown. Still in this second variant, each second stiffening element forms a continuous stiffening element which winds between the second sidewall and/or bead and the crown.

In a second configuration of the stiffening elements, it may be envisaged that each first stiffening element extends from the first sidewall and/or bead to the top and has one end in the first sidewall and/or bead. Similarly, it may be envisaged that each second stiffening element extends from the second sidewall and/or bead to the top and has one end in the second sidewall and/or bead.

In a first variant of this second configuration, it may be envisaged that each first stiffening element extends from the first sidewall and/or bead to the top and has one end in the top. Similarly, it may be envisaged that each second stiffening element extends from the second sidewall and/or bead to the top and has one end in the top.

In a second variant of this second configuration, each first stiffening element is respectively each second stiffening element and extends from the first sidewall and/or bead to the second sidewall and/or bead via the top and has an end in each first and second sidewall and/or bead.

Each stiffening element according to one of the designs or configurations previously defined can be characterized geometrically, in particular by its mean section Sm, this characteristic not necessarily being identical for all the stiffening elements. The mean section Sm is the average of the sections obtained by cutting the stiffening element by all the cylindrical surfaces, coaxial with the tire and radially included in the internal toric cavity. In the most frequent case of a constant section, the mean section Sm is the constant section of the stiffening element. The mean section Sm includes a largest characteristic dimension Dmax and a smallest characteristic dimension Dmin, the ratio of which R= Dmax/Dmin is called the aspect ratio. As examples, a stiffening element having a circular mean section Sm, having a diameter equal to d, has a shape ratio R=1, a stiffening element having a rectangular mean section Sm, having a length L and a width l, has a shape ratio R=L/l, and a stiffening element having an elliptical mean section Sm, having a major axis D and a minor axis d, has a shape ratio R=D/d.

A first type of preferred stiffening element, with an aspect ratio R at most equal to 3, is said to be one-dimensional. In other words, a stiffening element is considered one-dimensional when the largest characteristic dimension Dmax of its mean section Sm is at most equal to 3 times the smallest characteristic dimension Dmin of its mean section Sm. A one-dimensional stiffening element has a wire-like mechanical behavior, that is to say that it can only be subjected to extension or compression forces along its mean line. This is the reason why a one-dimensional stiffening element is usually called a wire-like stiffening element. Among the components commonly used in the field of tires, textile wire elements, consisting of an assembly of elementary textile monofilaments, or metal cables, consisting of an assembly of elementary metal monofilaments, can be considered as one-dimensional stiffening elements, because their average section Sm being substantially circular, the aspect ratio R is equal to 1, therefore less than 3.

A second type of stiffening element, with an aspect ratio R at least equal to 3, is said to be two-dimensional. In other words, a stiffening element is considered two-dimensional when the largest characteristic dimension Dmax of its mean section Sm is at least equal to 3 times the smallest characteristic dimension Dmin of its mean section Sm. A two-dimensional stiffening element has membrane-type mechanical behavior, i.e. it can only be subjected to extension or compression forces in its thickness defined by the smallest characteristic dimension Dmin of its mean section Sm. According to a first variant, a stiffening element, with an aspect ratio R at least equal to 3 and at most equal to 50, is said to be two-dimensional of the strip type. According to a second variant, a stiffening element, with an aspect ratio R at least equal to 50, is said to be two-dimensional of the film type.

The materials that can be used for each stiffening element are as described in WO2022/200717.

In a very advantageous embodiment, the or each first and/or second stiffening element is respectively a first and/or second wire stiffening element, preferably a first and/or second textile wire stiffening element. Preferably, the wire stiffening elements are identical, that is to say they have identical geometric characteristics and constituent materials.

These stiffening wire elements are usually called stays. The advantage of using stiffening wire elements is to have a stiffening structure with low mass and low hysteresis. The use of identical stiffening wire elements allows for a homogeneous distribution of forces between the stiffening elements.

By textile is meant that each wire stiffening element is non-metallic, for example made of a material chosen from a polyester, a polyamide, a polyketone, a polyvinyl alcohol, a cellulose, a mineral fiber, a natural fiber, an elastomeric material or a mixture of these materials. Polyesters include, for example, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PBT (polybutylene terephthalate), PBN (polybutylene naphthalate), PPT (polypropylene terephthalate), PPN (polypropylene naphthalate). Polyamides include aliphatic polyamides such as polyamides 4-6, 6, 6-6 (nylon), 11 or 12 and aromatic polyamides such as aramid. Preferably, the material is a polyester or an aliphatic polyamide.

Advantageously, in a variant making it possible to manufacture the tire by implementing a relatively simple method, each wire stiffening element extends in the toric cavity in a main direction forming, with the circumferential direction of the tire, an angle ranging, in absolute value, from 85° to 90°. In another variant making it possible to manufacture the tire by implementing a more complex method but making it possible to increase the circumferential stiffness, each wire stiffening element extends in the toric cavity in a main direction forming, with the circumferential direction of the tire, an angle ranging, in absolute value, from 45° to 85° as is explained in particular in WO2020/128225.

The present invention will be better understood upon studying the detailed description of embodiments, taken as non-limiting examples and illustrated by the appended drawings in which:

FIG. 1 is a view of a tire in a meridian section plane parallel to the axis of rotation according to a first exemplary embodiment of the invention;

FIG. 2 And FIG. 3 are schematic representations of the arrangement of the stiffening structure of the FIG. 1 in each first and second flank and/or bead; and

FIG. 4 , FIG. 5 , FIG. 6 , FIG. 7 , FIG. 8 , FIG. 9 , FIG. 10 And FIG. 11 are views analogous to that of the FIG. 2 of tires respectively according to second, third, fourth, fifth, sixth, seventh, eighth and ninth examples of embodiment of the invention.

Detailed description

In the figures relating to the tire, a reference X, Y, Z is shown corresponding to the usual axial (Y), radial (Z) and circumferential (X) directions of a tire.

The figures represent a tire 10 having a substantially toric shape around an axis of revolution substantially parallel to the axial direction Y. The tire 10 is intended for a passenger vehicle and has a dimension of 275/35ZR19. In the various figures, the tire 10 is shown in new condition, that is to say not having yet been driven.

The tire 10 according to the first embodiment described with reference to Figures 1 to 3 comprises a crown 12 comprising a tread 14 intended to come into contact with a ground when rolling and a crown reinforcement 16 extending in the crown 12 in the circumferential direction X. The tire 10 also comprises an inner layer 18.

The tire 10 further comprises a crown reinforcement identical to that described in WO2022/200717 comprising a working reinforcement 20 comprising working layers 24, 26 as well as a hoop reinforcement 22 comprising a hoop layer 28.

The tire 10 comprises first and second sidewalls 30A, 30B extending the crown 12 radially inwards. The second sidewall 30B is opposite the first sidewall 30A relative to the median plane M. The tire 10 further comprises first and second beads 32A, 32B extending each first and second sidewall 30A, 30B radially inwards respectively. The second bead 32B is opposite the first bead 32A relative to the median plane M. Each first and second sidewall 30A, 30B respectively connects each first and second bead 32A, 32B to the crown 12. The tire 10 is provided with an internal surface 34, intended to be in contact with the inflation gas of the tire, and which delimits a toric cavity 36 for inflation of the tire 10. The internal surface 34 is here carried by the inner layer 18.

The tire 10 comprises first and second radially inner reinforcing structures 38A, 38B respectively arranged in each first and second bead 32A, 32B.

Each first and second radially inner reinforcing structure 38A, 38B respectively comprises at least first and second radially inner circumferential reinforcing elements 40A, 40B, respectively arranged in each first and second bead 32A, 32B, comprising in particular at least first and second wire reinforcing elements as described in WO2022/200717.

Each first and second bead 32A, 32B respectively comprises a first and second axially inner circumferential attachment element 42A, 42B and a first and second axially outer circumferential attachment element 43A, 43B, here each comprising a bead wire, and intended to allow the attachment of the tire 10 to a mounting support of the tire 10, for example a rim. Each first and second axially inner circumferential attachment element 42A, 42B is arranged respectively inside each first and second axially outer circumferential attachment element 43A, 43B. Each first axially inner circumferential attachment element 42A is distinct from each first axially outer circumferential attachment element 43A. Each second axially inner circumferential attachment element 42B is distinct from each second axially outer circumferential attachment element 43B.

The first axially inner circumferential attachment element 42A comprises a radially outer end 421A and a radially inner end 422A delimiting a length L1 of the first axially inner circumferential attachment element 42A. The first axially outer circumferential attachment element 43A comprises a radially outer end 431A and a radially inner end 432A delimiting a length L1' of the first axially outer circumferential attachment element 43A.

The second axially inner circumferential attachment element 42B comprises a radially outer end 421B and a radially inner end 422B delimiting a length L2 of the second axially inner circumferential attachment element 42B. The second axially outer circumferential attachment element 43B comprises a radially outer end 431B and a radially inner end 432B delimiting a length L2' of the second axially outer circumferential attachment element 43B.

Each length L1, L1’, L2, L2’ ranges from 3 to 20 mm.

Each first and second axially inner circumferential attachment element 42A, 42B and axially outer circumferential attachment element 43A, 43B is wound circumferentially over at least two complete turns, preferably over at least three complete turns, more preferably over at least four complete turns, even more preferably over at least five complete turns and very preferably over at least six complete turns around the axis of revolution of the tire 10, and here over eight complete turns for the first and second axially inner circumferential attachment elements 42A, 42B and over seven complete turns for the first and second axially outer circumferential attachment elements 43A, 43B, so as to extend respectively in the first or second bead 32A, 32B radially inwards from the corresponding radially outer end 421A, 421B, 431A, 431B to the corresponding radially inner end 422A, 422B, 432A, 432B.

Each first and second axially inner circumferential attachment element 42A, 42B and axially outer circumferential attachment element 43A, 43B is arranged radially inside respectively each first and second radially inner reinforcing structure 38A, 38B, in particular each first and second axially inner circumferential attachment element 42A, 42B and axially outer circumferential attachment element 43A, 43B is arranged radially inside respectively each first and second radially inner circumferential reinforcing element 40A, 40B. Each first and second radially inner reinforcing structure 38A, 38B is arranged respectively radially outwardly relative to the radially outer end 421A, 421B of each first and second axially inner circumferential attachment element 42A, 42B and relative to the radially outer end 431A, 431B of each first and second axially outer circumferential attachment element 43A, 43B.

Each first radially inner circumferential reinforcing element 40A is distinct from each first axially inner circumferential attachment element 42A and axially outer circumferential attachment element 43A. Each second radially inner circumferential reinforcing element 40B is distinct from each second axially inner circumferential attachment element 42B and axially outer circumferential attachment element 43B.

The tire 10 further comprises first and second radially outer reinforcing structures 44A, 44B arranged in the crown 12 and each provided respectively with a first and second radially outer circumferential reinforcing element 46A, 46B arranged axially on either side of the median plane M of the tire 10 and here substantially symmetrically with respect to the median plane M of the tire 10. Each first and second radially outer circumferential reinforcing element 46A, 46B is as described in WO2022/200717.

The tire 10 comprises a carcass reinforcement 48 comprising a carcass layer 50 extending axially in the crown 12 radially inside the crown reinforcement 16 as well as radially in each first and second sidewall 30A, 30B and bead 32A, 32B. The crown reinforcement 16 is arranged radially between the tread 14 and the carcass reinforcement 48. The different crown layers 24, 26, 28 and carcass 50 are identical to those described in WO2022/200717.

The carcass layer 50 is therefore arranged in each first and second sidewall 30A, 30B and bead 32A, 32B and anchored in each first and second bead 32A, 32B.

In this case, the carcass layer 50 extends axially between each first and second axially inner circumferential attachment element 42A, 42B and each first and second axially outer circumferential attachment element 43A, 43B. Each first and second axially inner circumferential attachment element 42A, 42B and axially outer circumferential attachment element 43A, 43B is axially adjacent to the carcass layer 50 respectively in each first and second bead 32A, 32B.

The carcass layer 50 extends radially along each first and second axially inner circumferential attachment element 42A, 42B and outer circumferential attachment element 43A, 43B.

The tire 10 comprises a stiffening structure 52 extending in the toric cavity 36 from the first bead 32A to the crown 12 and which is anchored in the first bead 32A by being anchored around the first radially inner reinforcing structure 38A. The stiffening structure 52 extends in the toric cavity 36 from the second bead 32B to the crown 12 and is anchored in the second bead 32B by being anchored around the second radially inner reinforcing structure 38B. The stiffening structure 52 extends in the toric cavity 36 from the first bead 32A and from the second bead 32B to the crown 12 and is anchored in the crown 12 by being anchored around the radially outer reinforcing structures 44A, 44B.

The stiffening structure 52 comprises a plurality of stiffening elements 54 comprising a plurality of first stiffening elements 54A extending continuously in the toric cavity 36 and a plurality of second stiffening elements 54B extending continuously in the toric cavity 36. The first and second stiffening elements 54A, 54B are distributed circumferentially in the toric cavity 36.

Each stiffening element 54 is a textile wire stiffening element comprising an assembly of three multifilament strands of aliphatic polyamide, for example nylon, these three multifilament strands being individually helical at 190 turns per meter in one direction and then helical together at 190 turns per meter in the opposite direction. Each of these multifilament strands has a count equal to 188 tex.

Each first stiffening element 54A extends continuously from the first sidewall 30A and/or the first bead 32A to the top 12 and here from the first bead 32A to the top 12. Each second stiffening element 54B extends continuously from the second sidewall 30A and/or the second bead 32A to the top 12 and here from the second bead 32A to the top 12.

In order to ensure optimal anchoring of the first and second stiffening elements 54A, 54B, each first and second radially inner reinforcing structure 38A, 38B, in particular each first and second radially inner circumferential reinforcing element 40A, 40B, has relatively high extension and flexion rigidities.

In order to ensure optimal anchoring of the first and second stiffening elements 54A, 54B, each first and second radially outer reinforcing structure 44A, 44B, in particular each first and second radially outer circumferential reinforcing element 46A, 46B, has a relatively high extension rigidity and a relatively low bending rigidity in order to limit over-frettage of the crown 12 and not risk damaging the flattening of the tread 14.

Each first stiffening element 54A is anchored, in the first bead 32A, in or around the first radially inner reinforcing structure 38A. Each second stiffening element 54B is anchored in the second bead 32B, in or around the second radially inner reinforcing structure 38B.

Each first and second stiffening element 54A, 54B is also anchored, in the crown 12, respectively around each first and second radially outer reinforcing structure 44A, 44B, in particular around each first and second radially outer circumferential reinforcing element 46A, 46B. Here, each first and second stiffening element 54A, 54B is wound at least in part respectively around each first and second radially outer circumferential reinforcing element 46A, 46B.

Each first stiffening element 54A passes through the inner surface 34 at a first radially inner anchoring point 56A in the first bead 32A to be anchored around the first radially inner reinforcing structure 38A and at a first radially outer anchoring point 58A in the crown 12 to be anchored around the first radially outer reinforcing structure 44A. Thus, each first stiffening element 54A is anchored in the first bead 32A by extending into the first bead 32A from the first radially inner anchoring point 56A. Each first stiffening element 54A is anchored in the crown 12 by extending into the crown 12 from the first radially outer anchoring point 58A.

Each second stiffening element 54B passes through the inner surface 34 at a second radially inner anchoring point 56B in the second bead 32B to be anchored around the second radially inner reinforcing structure 38B and at a second radially outer anchoring point 58B in the crown 12 to be anchored around the second radially outer reinforcing structure 44B. Thus, each second stiffening element 54B is anchored in the second bead 32B by extending into the second bead 32B from the second radially inner anchoring point 56B. Each second stiffening element 54B is anchored in the crown 12 by extending into the crown 12 from the second radially outer anchoring point 58B.

Each first stiffening element 54A comprises a radially inner anchoring portion 541, a portion 543, and a radially outer anchoring portion 545, the portion 543 being extended on the one hand by the radially inner anchoring portion 541 and on the other hand by the radially outer anchoring portion 545.

Each second stiffening element 54B comprises a radially inner anchoring portion 542, a portion 544, and a radially outer anchoring portion 546, the portion 544 being extended on the one hand by the radially inner anchoring portion 542 and on the other hand by the radially outer anchoring portion 546.

The portion 543 of each first stiffening element 54A extends continuously in the toric cavity 36 from the first radially inner anchoring point 56A to the first radially outer anchoring point 58A.

The portion 544 of each second stiffening element 54B extends into the toric cavity 36 from the second radially inner anchoring point 56B to the second radially outer anchoring point 58B.

The radially inner anchoring portion 541 of each first stiffening element 54A extends from the first radially inner anchoring point 56A in the first bead 32A to be anchored in or around the first radially inner reinforcing structure 38A.

The radially outer anchoring portion 545 of each first stiffening element 54A extends from the first radially outer anchoring point 58A in the apex 12 to be anchored around the first radially outer reinforcing structure 44A.

The radially inner anchoring portion 542 of each second stiffening element 54B extends from the second radially inner anchoring point 56B in the second bead 32B to be anchored in or around the second radially inner reinforcing structure 38B.

The radially outer anchoring portion 546 of each second stiffening element 54B extends from the second radially outer anchoring point 58B in the apex 12 to be anchored around the second radially outer reinforcing structure 44B.

Each first stiffening element 54A forms a first continuous stiffening element which winds at least from the first bead 32A passing through the apex 12 and each second stiffening element 54B forms a second continuous stiffening element which winds at least from the second bead 32B passing through the apex 12. More precisely, the first and second stiffening elements 54A, 54B form a continuous stiffening element 54 which extends continuously from the first bead 32A to the second bead 32B passing through the apex 12 so as to wind from the first bead 32A to the second bead 32B.

The radially inner anchoring portion 541 of each first stiffening element 54A extends, from the first radially inner reinforcing structure 38A, radially inward at least partly along the first axially inner circumferential attachment element 42A axially adjacent to the radially inner anchoring portion 541, outside a first zone 49A located axially between the carcass layer 50 and the first axially inner circumferential attachment element 42A and located radially between the radially outer end 421A and the radially inner end 422A of the first axially inner circumferential attachment element 42A. The radially inner anchoring portion 541 extends radially inward at least partially along the first axially inner circumferential attachment element 42A without being anchored in the first axially inner circumferential attachment element 42A.

The radially inner anchoring portion 542 of each second stiffening element 54B extends, from the second radially inner reinforcing structure 38B, radially inward at least partly along the second axially inner circumferential attachment element 42B axially adjacent to the radially inner anchoring portion 542, outside a second zone 49B located axially between the carcass layer 50 and the second axially inner circumferential attachment element 42B and located radially between the radially outer end 421B and the radially inner end 422B of the second axially inner circumferential attachment element 42B. The radially inner anchoring portion 542 extends radially inward at least partially along the second axially inner circumferential attachment element 42B without being anchored in the second axially inner circumferential attachment element 42B.

The first radially outer anchoring point 58A is arranged axially on the same side as the first radially inner anchoring point 56A and the first radially inner reinforcing structure 38A relative to the median plane M. The second radially outer anchoring point 58B is arranged axially on the same other side as the second radially inner anchoring point 56B and the second radially inner reinforcing structure 38B relative to the median plane M. Each first and second radially inner anchoring point 56A, 56B and outer 58A, 56B is arranged so that the portions 543, 544 do not intersect in the toric cavity 36.

Each first and second stiffening element 54A, 54B is wound in part respectively around each first and second radially inner circumferential reinforcing element 40A, 40B, each first and second radially inner circumferential reinforcing element 40A, 40B being respectively the only radially inner circumferential reinforcing element of each corresponding first and second radially inner reinforcing structure 38A, 38B and being wound circumferentially over a complete turn around the axis of revolution.

More specifically and with reference to Figures 2 and 3, each radially inner anchoring portion 541 and 542 of each first and second stiffening element 54A and 54B comprises first, second and third branches 5411, 5412, 5413 and 5421, 5422, 5423 arranged successively respectively in each first and second bead 32A and 32B.

Each first branch 5411, 5421 extends radially inward and axially outward from each first and second radially inner anchoring point 56A, 56B, each first branch 5411, 5421 being here substantially straight. Each second branch 5412, 5422, which is here substantially straight, extends radially and axially inward respectively from each third branch 5413, 5423 which connects each first branch 5411, 5421 and each second branch 5412, 5422. Each third branch 5413, 5423 is partially wrapped around the first and second radially inner circumferential reinforcing element 40A, 40B and therefore here curved.

Each second branch 5412, 5422 extends radially at least partially along each first and second axially inner circumferential attachment element 42A, 42B. More specifically, each second branch 5412, 5422 extends radially at least partially inside each radially outer end 421A, 421B of each first and second axially inner circumferential attachment element 42A, 42B.

Each radially inner anchoring portion 541, 542 extends at least partly axially inside each first and second axially inner circumferential attachment element 42A, 42B.

Each radially inner anchoring portion 541, 542 extends radially inward to a point arranged radially inside the radially outer end 421A, 421B of each first and second axially inner circumferential attachment element 42A, 42B.

Each radially inner anchoring portion 541, 542 extends radially inward to a point arranged radially outside the radially inner end 422A, 422B of each first and second circumferential attachment element 42A, 42B.

Other embodiments will now be described with reference to Figures 4 to 12 in which elements similar to those of the first embodiment are designated by identical references. In the examples described with reference to Figures 4 to 12, the radially inner anchoring portion 542 of each second stiffening element 54B is defined mutatis mutandis with respect to the radially inner anchoring portion 541 of each first stiffening element 54A.

The second example of realization illustrated in the FIG. 4 differs from the first embodiment in that the radially inner anchoring portion 541 of each first stiffening element 54A is anchored in the first main radially inner circumferential reinforcing element 42A.

The third example of realization illustrated in the FIG. 5 differs from the first embodiment in that the first radially inner reinforcing structure 38A comprises a first radially inner circumferential reinforcing element 40A wound circumferentially over two complete turns around the axis of revolution superimposed in the radial direction. The first radially inner reinforcing structure 38A also comprises a first complementary radially inner circumferential reinforcing element 40A' distinct from the first radially inner circumferential reinforcing element 40A. The first complementary radially inner circumferential reinforcing element 40A' is wound circumferentially over one complete turn around the axis of revolution. The radially inner anchoring portion 541 extends at least in part between the first radially inner circumferential reinforcing element 40A and the first complementary radially inner circumferential reinforcing element 40A'.

The fourth example of realization illustrated in the FIG. 6 differs from the first embodiment in that the first radially inner reinforcing structure 38A comprises a first radially inner circumferential reinforcing element 40A wound circumferentially over three complete turns around the axis of revolution arranged side by side in the axial direction. The first radially inner reinforcing structure 38A also comprises a first complementary radially inner circumferential reinforcing element 40A' similar to that of the third embodiment.

The fifth example of realization illustrated in the FIG. 7 differs from the first embodiment in that the radially inner anchoring portion 541 of each first stiffening element 54A extends radially inward at least from the radially outer end 421A of the first axially inner circumferential attachment element 42A over at least 10%, preferably at least 20% of the length L1 of the first axially inner circumferential attachment element 42A. In this case, L1=15 mm and the length of the radially inner anchoring portion 541 from the radially outer end 421A is here substantially equal to 8 mm.

The sixth example of realization illustrated in the FIG. 8 differs from the fifth example of realization illustrated in FIG. 7 in that the radially inner anchoring portion 541 extends radially inwardly to a point arranged radially inside the radially inner end 422A of the first axially inner circumferential attachment element 42A.

The seventh example of realization illustrated in the FIG. 9 differs from the first embodiment in that the first bead 32A further comprises a first additional radially inner circumferential reinforcing element 60A offset axially inward relative to the first axially inner circumferential attachment element 42A, and here wound circumferentially over four complete turns around the axis of revolution so that the first additional radially inner circumferential reinforcing element 60A extends in the first bead 32A radially inward and axially inward.

The radially inner anchoring portion 541 of each first stiffening element 54A is arranged axially in part between the first axially inner circumferential attachment element 42A and the first additional radially inner circumferential reinforcement element 60A.

The eighth example of realization illustrated in the FIG. 10 differs from the fifth example of realization illustrated in FIG. 7 in that the radially inner anchoring portion 541 axially passes through the carcass layer 50 to be anchored around the first radially inner circumferential reinforcing element 40A arranged axially outside the carcass layer 50. The radially inner anchoring portion 541 extends at least partly axially outside the first axially outer circumferential attachment element 43A.

In this eighth embodiment, the first axially outer circumferential attachment element 43A is axially adjacent to the radially inner anchoring portion 541 so that the radially inner anchoring portion 541 extends, from the first radially inner reinforcing structure 38A, radially inward at least partly along the first axially outer circumferential attachment element 43A.

In this eighth embodiment, the radially inner anchoring portion 541 extends outside the first zone 49A' located axially between the carcass layer 50 and the first axially outer circumferential attachment element 43A and located radially between the radially outer end 431A and the radially inner end 432A of the first axially outer circumferential attachment element 43A.

In this eighth embodiment, the radially inner anchoring portion 541 of each first stiffening element 54A extends radially inward at least from the radially outer end 431A of the first circumferential attachment element 42A over at least 10%, preferably at least 20% of the length L1' of the first axially outer circumferential attachment element 43A. In this case, L1'=15 mm and the length of the radially inner anchoring portion 541 from the radially outer end 431A is here substantially equal to 11 mm.

The ninth example of realization illustrated in the FIG. 11 differs from the first embodiment in that the carcass reinforcement 48 comprises a radially and axially inner carcass layer 50 and a radially and axially outer carcass layer 51. The bead 32A comprises circumferential attachment elements axially inner 42A, axially intermediate 43A and axially outer 45A.

The radially and axially inner carcass layer 50 extends radially along the first axially inner circumferential gripping element 42A and along the first axially intermediate circumferential gripping element 43A, the first axially inner circumferential gripping elements 42A and axially intermediate 43A being axially adjacent to the radially and axially inner carcass layer 50.

The radially and axially outer carcass layer 51 extends radially along the first axially intermediate circumferential attachment element 43A and along the first axially outer circumferential attachment element 45A, the first axially intermediate 43A and axially outer 45A circumferential attachment elements being axially adjacent to the radially and axially outer carcass layer 51.

Each circumferential attachment element 42A, 43A, 45A is arranged radially inside the first radially inner reinforcing structure 38A and extends in the first bead 32A radially inward from a radially outer end 421A, 431A, 451A to a radially inner end 422A, 432A, 452A respectively. The radially inner anchoring portion 541 extends, just as in the first embodiment, from the first radially inner reinforcing structure 38A, radially inward at least partly along said first circumferential attachment element 42A which is axially adjacent to the radially inner anchoring portion 541.

Comparative tests

A tire was tested according to the fifth example of realization illustrated in FIG. 7 and a control tire identical to the tire according to the fifth embodiment but in which the radially inner anchoring portion of each stiffening element extends in each first and second zone located axially between the carcass layer and each first and second axially inner circumferential attachment element and located radially between the radially outer end and the radially inner end of each first and second axially inner circumferential attachment element. These tests were carried out on a rolling machine simulating the stresses exerted by the Nürburgring circuit (Germany) on the tire tested under extreme racing stress conditions so as to cause degradation of the stiffening structure.

The control tire has completed 2 revolutions at the end of which a separation of the first axially inner circumferential attachment element is observed, leading to a sudden loss of tire pressure.

The tire according to the invention also completed 2 laps, at the end of which a loosening of the stiffening elements in the first bead was observed without affecting the integrity of the rest of the tire structure. Thus, the tire according to the invention managed to complete 18 additional laps without any further damage, in particular without any sudden loss of pressure despite the loss of the advantages provided by the stiffening structure.

The invention is not limited to the embodiments previously described.

In accordance with the invention, embodiments may be envisaged in which each first and second bead and/or sidewall comprises a single first and second circumferential attachment element.

It may be envisaged to combine the characteristics of the invention described above with anchoring members as described in application FR2315326 and/or with a sealing layer as described in application FR2315327 or the absence of a sealing layer as described in FR2315327 and/or main and complementary stiffening elements as described in FR2315325 and/or inner and outer layers as described in FR2315328 filed in the name of the applicant of the present application.

Claims (14)

A tire (10) comprising a crown (12), first and second sidewalls (30A, 30B) each extending the crown (12) radially inward, first and second beads (32A, 32B) respectively extending the first and second sidewalls (30A, 30B) radially inward, the tire (10) being provided with an internal surface (34) delimiting a toric cavity (36) for inflating the tire (10), the tire (10) having a substantially toric shape around an axis of revolution and comprising:
- at least one first radially internal reinforcing structure (38A) arranged in the first sidewall (30A) and/or bead (32A),
- a stiffening structure (52) comprising at least one first stiffening element (54A) extending continuously in the toric cavity (36) from at least the first flank (30A) and/or bead (32A) to at least the apex (12), and comprising at least one radially inner anchoring portion (541) extending in the first flank (30A) and/or bead (32A) from a radially inner anchoring point (56A) of said first stiffening element (54A) to be anchored in or around said first radially inner reinforcing structure (38A),
- at least one first circumferential attachment element (42A; 43A) intended to allow the attachment of the tire (10) to a mounting support, and extending in the first sidewall (30A) and/or bead (32A) radially inward from a radially outer end (421A; 431A) to a radially inner end (422A; 432A) of said first circumferential attachment element (42A; 43A), said radially inner anchoring portion (541) of said first stiffening element (54A) extending, from said first radially inner reinforcing structure (38A), radially inward at least partly along said first circumferential attachment element (42A; 43A), said first circumferential attachment element (42A; 43A) being axially adjacent to said portion radially inner anchor (541),
- a carcass reinforcement (48) comprising at least one carcass layer (50) arranged at least in the first sidewall (30A) and/or bead (32A) and extending radially along said first circumferential attachment element (42A; 43A), said first circumferential attachment element (42A; 43A) being axially adjacent to the carcass layer (50),
characterized in that said radially inner anchoring portion (541) of said first stiffening element (54A) extends outside a zone (49A; 49A') located:
- axially between said carcass layer (50) and said first circumferential attachment element (42A; 43A), and
- radially between the radially outer end (421A; 431A) and the radially inner end (422A; 432A) of said first circumferential attachment element (42A; 43A). Tire (10) according to the preceding claim, comprising:
- at least one second radially inner reinforcing structure (38B) arranged in the second sidewall (30B) and/or bead (32B),
- the stiffening structure (52) comprising at least one second stiffening element (54B) extending continuously in the toric cavity (36) from at least the second flank (30B) and/or bead (32B) to at least the apex (12), and comprising at least one radially inner anchoring portion (542) extending in the second flank (30B) and/or bead (32B) from a radially inner anchoring point (56B) of said second stiffening element (54B) to be anchored in or around said second radially inner reinforcing structure (38B),
- at least one second circumferential attachment element (42B; 43B) intended to allow the attachment of the tire (10) to a mounting support, and extending in the second sidewall (30B) and/or bead (32B) radially inward from a radially outer end (421B; 431B) to a radially inner end (422B; 432B) of said second circumferential attachment element (42B; 43B), said radially inner anchoring portion (542) of said second stiffening element (54B) extending, from said second radially inner reinforcing structure (38B), radially inward at least partly along said second circumferential attachment element (42B; 43B), said first circumferential attachment element (42B; 43B) being axially adjacent to said portion radially inner anchor (542),
- said carcass layer (50) being arranged at least in the second sidewall (30B) and/or bead (32B) and extending radially along said second circumferential attachment element (42B; 43B), said second circumferential attachment element (42B; 43B) being axially adjacent to the carcass layer (50),
tire in which said radially inner anchoring portion (542) of said second stiffening element (54B) extends outside a zone (49B; 49B') located:
- axially between said carcass layer (50) and said second circumferential attachment element (42B; 43B), and
- radially between the radially outer end (421B; 431B) and the radially inner end (422B; 432B) of said second circumferential attachment element (42B; 43B). A tire (10) according to any preceding claim, wherein said radially inner anchoring portion (541) of said first stiffening element (54A) extends radially inward to a point arranged radially inside the radially outer end (421A; 431A) of said first circumferential attachment element (42A; 43A). A tire according to any one of claims 1 to 3, wherein said radially inner anchoring portion (541) of said first stiffening element (54) extends radially inward to a point arranged radially outside the radially inner end (422A; 432A) of said first circumferential attachment element (42A; 43A). A tire according to any one of claims 1 to 3, wherein said radially inner anchoring portion (541) of said first stiffening element (54) extends radially inward to a point arranged radially inside the radially inner end (422A; 432A) of said first circumferential attachment element (42A; 43A). A tire (10) according to any one of the preceding claims, wherein said radially inner anchoring portion (541) of said first stiffening element (54A) extends radially inward at least from the radially outer end (421A; 431A) of said first circumferential attachment element (42A; 43A) over at least 10%, preferably at least 20% of a length of said first circumferential attachment element (42A; 43A). A tire (10) according to any preceding claim, wherein said radially inner anchoring portion (541) of said first stiffening element (54A) comprises at least first and second branches (5411, 5412), said first branch (5411) extending radially inward and axially outward from the radially inner anchoring point (56A) of said first stiffening element (54A), said second branch (5412) extending radially inward and axially inward from said first branch (5411) or from a third branch (5413) of said first stiffening element (54A) connecting said first branch (5411) and said second branch (5412). Tire (10) according to the preceding claim, in which the second branch (5412) extends radially at least partly along said first circumferential attachment element (42A; 43A). A tire (10) according to any one of claims 1 to 8, wherein said radially inner anchoring portion (541) of said first stiffening element (54A) extends radially inward at least partly along said first circumferential attachment element (42A; 43A) without being anchored in the first circumferential attachment element (42A; 43A). A tire (10) according to any one of claims 1 to 8, wherein said radially inner anchoring portion (541) of said first stiffening element (54A) extends radially inward at least partly along said first circumferential attachment element (42A; 43A) while being anchored in or around said first circumferential attachment element (42A; 43A). A tire (10) according to any preceding claim, comprising a first axially inner circumferential attachment element (42A) and a first axially outer circumferential attachment element (43A) for enabling the tire (10) to be attached to a mounting support, and arranged radially within said first radially inner reinforcing structure (38A), each first axially inner (42A) and outer (43A) circumferential attachment element being axially adjacent to the carcass layer (50) and extending in the first sidewall (30A) and/or bead (32A) radially inward from a radially outer end (421A, 431A) to a radially inner end (422A, 432A) of said first axially inner (42A) and outer (43A) circumferential attachment element respectively, said layer of carcass (50) extends radially along each first axially inner (42A) and outer (43A) circumferential attachment element and axially between said first axially inner circumferential attachment element (42A) and said first axially outer circumferential attachment element (43A). A tire (10) according to claim 11, wherein said radially inner anchoring portion (541) of said first stiffening element (54A) extends at least partly axially inside said first axially inner circumferential attachment element (42A). A tire (10) according to claim 11, wherein said radially inner anchoring portion (541) of said first stiffening element (54A) axially passes through said carcass layer (50) and extends at least partly axially outside said first axially outer circumferential attachment element (43A). A tire (10) according to any one of the preceding claims, wherein said first radially inner reinforcing structure (38A) comprises a first radially inner circumferential reinforcing element (40A) separate from the first circumferential attachment element (42A; 43A).