Tire with improved interface

Abstract

The invention relates to a tyre for a passenger vehicle, comprising a reinforcement layer (36) and a reinforcement layer (44) extending radially from a bead (32) to a sidewall (30). The reinforcement layer (44) is arranged axially between the reinforcement layer (36) and the outer layer (42) of the sidewall (30), in contact with the reinforcement layer (36), and in contact with a portion of the outer layer (42) of the sidewall (30). The ratio R of the modulus MA100R of the polymer matrix of the reinforcement layer (36) at 100% elongation to the modulus MA10B of the reinforcement layer (44) at 10% elongation satisfies R * 1000 > = (0.011 * MA10B * MA10B)-1.71 * MA10B + 86.70.

Description

Technical Field

[0001] The present invention relates to a tire. A tire is understood to be a carcass designed to form, by cooperating with a supporting element (such as a rim), a cavity that can be pressurized to a pressure above atmospheric pressure. The tire according to the invention has a generally annular structure with rotational symmetry about its main axis. Background Art

[0002] Tires for passenger vehicles are known from the prior art, comprising a crown, two beads, and two sidewalls connecting each bead to the crown. The tire also comprises a carcass reinforcement comprising one or more carcass plies anchored in each bead. The crown also comprises a crown reinforcement, the or each carcass ply extending radially in each sidewall and extending axially in the crown radially inwardly of the crown reinforcement. The or each carcass ply comprises reinforcing elements embedded in a polymer matrix.

[0003] The tire further includes a reinforcing layer extending radially from each bead to each sidewall adjacent to the bead. In each adjacent sidewall, the reinforcing layer is axially arranged between the axially outermost carcass layer and the outer layer of the sidewall that supports the outer surface of the sidewall. In each sidewall, the reinforcing layer is arranged to contact a portion of the axially outermost carcass layer in each sidewall and to contact a portion of the outer layer of each sidewall.

[0004] Particularly under exceptionally severe conditions of use, in particular under conditions of high loads and / or pressures below the recommended pressures, a significant increase in energy dissipation and temperature rise at the interface between the reinforcement layer and the axially outermost carcass layer has been observed. Summary of the Invention

[0005] The purpose of the present invention is to control the energy dissipation and the temperature rise between the reinforcing layer and the axially outermost carcass layer, in particular under extremely severe conditions of use.

[0006] To this end, the subject of the invention is a tire for passenger vehicles, comprising:

[0007] a crown, two beads, two sidewalls connecting each bead to the crown, each sidewall comprising an outer layer of said sidewall carrying its outer surface,

[0008] a reinforcing layer extending radially in at least one sidewall and comprising filamentary reinforcing elements embedded in a polymer matrix,

[0009] a reinforcing layer extending radially from one bead to a sidewall adjacent to said bead, in said sidewall said reinforcing layer:

[0010] - arranged axially between the reinforcing layer and the outer layer of said sidewall, and

[0011] - in contact with at least a portion of the reinforcing layer and in contact with at least a portion of the outer layer of said sidewall,

[0012] The ratio R of the modulus MA100R of the polymer matrix of the reinforcing layer at 100% elongation to the modulus MA10B of the strengthening layer at 10% elongation satisfies R×1000≥(0.011×MA10B×MA10B)−1.71×MA10B+86.70.

[0013] Even under exceptionally harsh operating conditions, the tire according to the present invention exhibits relatively low temperature rise and energy dissipation. Specifically, the inventors have discovered that by limiting the difference between the modulus at the operating point of the polymer matrix of the reinforcing layer and the modulus at the operating point of the reinforcement layer, the stress difference at the interface between the polymer matrix of the reinforcing layer and the reinforcement layer is limited. However, the operating point of the polymer matrix of the reinforcing layer is at a relatively high elongation, while the operating point of the reinforcement layer is at a relatively low elongation. Therefore, the moduli at 100% elongation and 10% elongation represent the operating point of the reinforcing layer and the operating point of the reinforcement layer, respectively. Therefore, the inventors have determined that the ratio R represents the sensitivity of the interface between the polymer matrix of the reinforcing layer and the reinforcement layer. For a given value of the modulus MA10B, the higher the ratio, the lower the sensitivity of the interface.

[0014] To explain this, the inventors hypothesize that, for a given value of the modulus MA10B, by increasing the value of the ratio R, the stress differences at the interface that lead to energy dissipation and temperature increase are limited.

[0015] The reinforcing layer extends radially from one bead to the sidewall adjacent to said bead. The reinforcing layer is therefore present partly in the sidewall and partly in the bead, the proportion of one part relative to the other varying according to the tire under consideration and the properties that a person skilled in the art wishes to impart to it.

[0016] The reinforcing layer does not define the outer surface of the sidewall.

[0017] The outer surface is the surface of the tire that is in contact with the air at atmospheric pressure and is visible from the outside of the tire.

[0018] As for the modulus MA10B at 10% elongation, it is the elastic modulus of the compound measured at an elongation value of 0.1 (i.e. 10% elongation expressed as a percentage) in a uniaxial tensile test. Uniaxial tension is applied to the specimen at a constant rate, and the elongation and force are measured. The measurements are carried out using an INSTRON type tensile testing machine at a temperature of 23° C. and a relative humidity of 50% (standard ISO 23529). The conditions for measuring and using the results to determine the elongation and stress are as described in standard NFISO 37: 2012-03. The stress at 0.1 elongation is determined, and the tensile modulus of elasticity at 10% elongation is calculated by determining the ratio of this stress value to the elongation value. A person skilled in the art knows how to choose and adjust the dimensions of the specimen according to the amount of compound available and usable, in particular when the specimen is taken from a tire. The modulus MA100R is determined in the same way, with necessary changes.

[0019] When it is possible to determine the moduli MA10B and MA100R on a tire, they are measured on the polymer matrix and on the reinforcing layer defining the interface between the reinforcing layer and the reinforcing layer situated in the sidewalls.

[0020] Preferably, the polymer matrix is an elastomeric matrix.

[0021] Preferably, unlike the reinforcing layer, the reinforcing layer does not include any filamentary reinforcing elements embedded therein. Therefore, preferably, the reinforcing layer is made of a polymer compound, preferably an elastomeric compound. Such reinforcing compounds are known, in particular, from EP0678404 and WO2010072736.

[0022] The expression "filamentous reinforcing elements" refers to elements that provide mechanical reinforcement to a polymer matrix and are intended to be embedded in said polymer matrix. Each reinforcing element is filamentous, meaning that its length is at least 10 times greater than the largest dimension of its cross-section, regardless of the shape of said cross-section: circular, elliptical, rectangular, polygonal, in particular rectangular or square or oval. In the case of a rectangular cross-section, the thread-like reinforcing elements have the shape of a strip.

[0023] The matrix or compound is called a polymer matrix or polymer compound because it is based on a polymer composition that may contain one or more polymers chosen, for example, from thermoplastic polymers, thermosetting polymers, elastomers, thermoplastic elastomers, as well as fillers and other components commonly used in the field of compositions for tires, in particular compositions for embedding filamentary reinforcing elements or compositions for reinforcement layers.

[0024] The expression “sidewall adjacent to the bead” means the sidewall arranged on the same side of the midplane of the tire as the bead is located.

[0025] The tyre according to the invention has a substantially annular shape around an axis of rotation (substantially coinciding with the axis of rotation of the tyre).This axis of rotation defines three directions commonly used by those skilled in the art: axial, circumferential and radial.

[0026] The expression "axial direction" means a direction substantially parallel to the axis of rotation of the tyre, ie the axis of rotation of the tyre.

[0027] The expression "circumferential direction" means a direction substantially perpendicular to the axial direction and to the radius of the tire (in other words tangential to a circle centered on the axis of rotation of the tire).

[0028] The expression "radial direction" is intended to mean a direction along a radius of the tire, ie any direction intersecting the axis of rotation of the tire and substantially perpendicular to this axis.

[0029] The expression “median plane of the tire” (denoted M) means the plane perpendicular to the axis of rotation of the tire, axially midway between the two beads and passing through the axial middle of the crown reinforcement.

[0030] The expression "equatorial circumferential surface of the tire" is understood to mean the combination of planes which, in each meridian section plane, pass through the equator of the tire (denoted by E) and are perpendicular to the median plane and to the radial direction. The equator of the tire is the axis in a meridian section plane (a plane perpendicular to the circumferential direction and parallel to the radial and axial directions) which is parallel to the axis of rotation of the tire and is situated equidistant between the radially outermost point of the tread intended to come into contact with the ground and the radially innermost point of the tire intended to come into contact with a support, such as a rim.

[0031] The expression “meridian plane” means a plane parallel to and containing the axis of rotation of the tire and perpendicular to the circumferential direction.

[0032] The expressions “radially inside” and “radially outside” mean respectively closer to and further away from the tire's axis of rotation. The expressions “axially inside” and “axially outside” mean respectively closer to and further away from the tire's mid-plane.

[0033] The term "bead" refers to the portion of the tire intended to attach the tire to a mounting support, such as a wheel comprising a rim. Each bead is therefore intended to specifically come into contact with the flange of the rim, thereby allowing attachment. According to the 2021 ETRTO Standards Manual, the radially outer end of the outer surface of the tire bead is defined as the radially outermost point at which the outer surface of the tire contacts the measuring rim of the tire when the tire is inflated to its nominal pressure on the measuring rim. Thus, the bead and sidewall are bounded by a straight line perpendicular to the outer surface of the tire at that point.

[0034] Any numerical interval expressed by the expression "between a and b" represents a numerical range extending from greater than a to less than b (i.e., excluding the limits a and b), while any numerical interval expressed by the expression "a to b" means a numerical range extending from a to b (i.e., including the strict limits a and b).

[0035] The tire is intended for passenger vehicles as defined in the 2021 ETRTO Manual of Standards. Optionally, the cross-section of this tire in the meridian cross-sectional plane is characterized by a section height H and a nominal section width SW within the meaning of the 2021 ETRTO Manual of Standards satisfying the ratio H / SW, expressed as a percentage, of at most 90 and at least 20, and the nominal section width SW is at least 185 mm and at most 385 mm. Furthermore, the diameter D at the flange (which defines the diameter of the rim on which the tire is mounted) is optionally at least 14 inches and at most 24 inches. Finally, and still optionally, the load index LI ranges from 80 to 116.

[0036] The sidewall height H is defined by H = SW × AR / 100, where SW is the nominal section width of the tire and AR is the nominal aspect ratio of the tire, for example as shown in the 2021 ETRTO Standards Manual.

[0037] Advantageously, the reinforcing layer is the axially outermost layer in the or each sidewall. In a meridian cross-sectional plane, the axially outermost reinforcing layer has the greatest curved length in contact with the reinforcing layer in the sidewall. Therefore, taking into account the continuity of the axially outermost reinforcing layer, the axially outermost reinforcing layer is the axially outermost reinforcing layer in the largest part of the sidewall. Typically, the axially outermost reinforcing layer is the axially outermost layer at the equator.

[0038] In an embodiment in which both sides of a tire according to the invention are arranged, said tire comprises:

[0039] one or more reinforcing layers extending radially in each sidewall, the or each reinforcing layer comprising filamentary reinforcing elements embedded in a polymer matrix,

[0040] - two reinforcing layers arranged on either side of the mid-plane of the tire, each reinforcing layer extending radially from each bead to each sidewall adjacent to said bead, in said sidewalls, each reinforcing layer:

[0041] ○ is arranged axially between the reinforcing layer and the outer layer of said sidewall, and

[0042] ○ in contact with at least a portion of the reinforcing layer and in contact with at least a portion of the outer layer of said sidewall,

[0043] The ratio R of the modulus MA100R of the polymer matrix of the reinforcing layer at 100% elongation to the modulus MA10B of the reinforcing layer arranged in the sidewall at 10% elongation satisfies R×1000≥(0.011×MA10B×MA10B)−1.71×MA10B+86.70.

[0044] In an optional but advantageous embodiment, R×1000≧(0.0106×MA10B×MA10B)−1.72×MA10B+90.40.

[0045] In an optional but advantageous embodiment, R×1000≤(0.0127×MA10B×MA10B)−2.03×MA10B+109.

[0046] In an optional but advantageous embodiment, MA10B ≥ 30.0 MPa, preferably MA10B ≥ 40.0 MPa, and more preferably 40.0 MPa ≤ MA10B ≤ 70.0 MPa. Because the reinforcing layer has a greater stiffness, it can improve the dynamic behavior of the tire by strengthening the area in which it is located. In particular, it can increase the tire's cornering stiffness.

[0047] In an optional but advantageous embodiment, MA100R ≥ 1.0 MPa, preferably MA100R ≥ 1.5 MPa.

[0048] In an optional but advantageous embodiment, MA100R≤2.5 MPa, preferably MA100R≤2.0 MPa.

[0049] The embodiments are particularly sensitive to energy dissipation and temperature rise between the reinforcement layer and the axially outermost carcass layer. This is because the development of electric and hybrid passenger vehicles has increased vehicle weight, particularly due to the relatively high weight of batteries, which is generally proportional to the vehicle's range. Therefore, to increase the range of an electric vehicle, for example, the battery size must be increased, and thus the vehicle's weight. Simply put, current estimates indicate that each kilometer of range driven by an electric motor adds one kilogram to the vehicle's weight. Therefore, to achieve a range of 500 kilometers, a vehicle propelled by an internal combustion engine would need to increase its weight by approximately 500 kg. These vehicles require tires capable of withstanding extremely high loads. Consequently, tire manufacturers have decided to develop a completely new tire type, currently referred to as High Load Capacity in the 2021 ETRTO Standards Manual. This new tire type ensures that a tire of a given size can withstand higher loads than a tire of the same size in standard or extra load versions. For the 255 / 35R18 size, the high load capacity version therefore has a load index of 98, indicating that it can withstand a load of 750 kg at a pressure of 290 kPa. The 255 / 35R18 size tire in its extra load version has a load index of 94. This means that at a pressure of 290 kPa, the tire can withstand a load of 670 kg. The 255 / 35R18 size tire in its standard load version (abbreviated as SL) has a load index of 90 and can withstand a load of 600 kg at a pressure of 250 kPa.

[0050] Therefore, due to the relatively high loads they need to withstand, high load capacity tires are required to operate under very demanding conditions of use, especially under high load conditions. Therefore, it is particularly advantageous that, in certain embodiments, the tire of the present invention is a high load capacity tire according to the 2021 ETRTO standard manual.

[0051] By increasing the load index of the tire of the present invention relative to the load index of the extra-load version of the tire of the same size, the high-load capacity type tire can increase the load-bearing capacity of the installation assembly without changing the space, compactness and comfort of the vehicle in which the tire is used. In particular, since the dimensions of the tire are the same as those of the extra-load version tire, the installation assembly does not take up any more space than the extra-load version tire. The high-load capacity type tire can be equipped with a unique marking to distinguish it from the standard load version and the extra-load version (for example, a marking of the type HL (High Load) or XL+ (Extra Load+)). Such marking is disclosed in particular in the 2021 ETRTO Standards Manual (section General Notes - Passenger Car Tyres, page 3). Examples of the dimensions of the high-load capacity type tire are also disclosed in the 2021 ETRTO Standards Manual (section 9.1, section Passenger Car Tyres - Tyres with Metric Designation, page 44).

[0052] A tire of the high load capacity type may be characterized in that its load index LI satisfies LI≥LI'+1, where LI' is the load index of an extra load tire of the same size according to the ETRTO Standard Manual of 2021. The load index LI' is the load index of an extra load tire of the same size, i.e. the same nominal section width, the same nominal aspect ratio, the same construction (R and ZR are considered to be the same) and the same nominal rim diameter. The load index LI' is given in the ETRTO Standard Manual of 2021, in particular in the section entitled "Passenger Car Tyres - Tyres with Metric Designation" on pages 22 to 43. Depending on the size, LI=LI'+1 or LI=LI'+2 or LI=LI'+3 or LI=LI'+4. In most embodiments, LI'+1≤LI≤LI'+4, or even LI'+2≤LI≤LI'+4.

[0053] Technical solutions for designing tyres of the high load capacity type are described in particular in WO 2022 / 074341, WO 2022 / 074342, WO 2022 / 074343, WO 2022 / 074344 and WO 2022 / 074345.

[0054] Advantageously, the sidewall height H of the tire is defined by H=SW×AR / 100, where SW is the nominal cross-sectional width of the tire, AR is the nominal aspect ratio of the tire, and the load index LI satisfies H / LI≤1.00, preferably 0.72≤H / LI≤1.00, more preferably 0.72≤H / LI≤0.95, wherein SW, AR and LI are defined in accordance with the 2021 ETRTO standard manual. Therefore, the present invention is preferably applicable to tires that may have relatively significant deflection because they have a relatively high load index relative to the sidewall height, and the sidewall height is relatively low relative to the load index. In particular, due to the relatively significant deflection, the interface between the reinforcing layer and the carcass layer is subjected to higher stress and energy dissipation occurs (the present invention can advantageously control energy dissipation).

[0055] The nominal section width SW, the nominal aspect ratio AR and the load index LI are shown in particular by the dimension markings engraved on the sidewall of the tyre and comply with the ETRTO Standards Manual of 2021.

[0056] In some embodiments, the tire comprises a carcass reinforcement comprising at least one carcass ply anchored in each bead, the crown comprising a crown reinforcement, at least one carcass ply extending radially in each sidewall and extending axially in the crown radially inside the crown reinforcement, at least one carcass ply forming a reinforcing layer. In these embodiments, the carcass ply forms the reinforcing layer, the polymer matrix is a calendered matrix of the carcass ply, and the filamentary reinforcing elements are filamentous reinforcing elements of the carcass ply.

[0057] Optionally, the carcass layer anchored in each bead is axially delimited by its two axial ends and comprises filamentary carcass reinforcing elements extending axially from one axial end of the carcass layer to the other axial end.

[0058] Optionally, each filamentary carcass reinforcing element extends in a main direction forming an angle with the circumferential direction of the tire having an absolute value greater than or equal to 60°, preferably ranging from 80° to 90°.

[0059] In a first variant of the first configuration, the carcass reinforcement comprises a single carcass layer anchored in each bead, extending radially in each sidewall and extending axially in the crown radially inside the crown reinforcement, said single carcass layer forming a reinforcing layer.

[0060] In certain embodiments of this first variant form, a single carcass layer is wound around the circumferential reinforcement elements of each bead so that the axially inner portion of the first carcass layer is axially arranged inboard of the axially outer portion of the carcass layer, and each axial end of the carcass layer is radially arranged on the outside of each circumferential reinforcement element, the portion of the reinforcement layer in contact with the reinforcement layer arranged in the sidewall being formed by a portion of the axially inner portion of the single carcass layer in the sidewall. In these embodiments, the axially outer portion of the carcass layer is relatively short. Therefore, the reinforcement layer is in contact with at least a portion of the axially outer portion at least in the bead and at least a portion of the axially inner portion at least in the sidewall. Optionally, the tire includes a filling layer, which is arranged at least axially between the axially inner and axially outer portions of the single carcass layer and extends radially from the circumferential reinforcement elements to the crown of the tire, the reinforcement layer also being in contact with at least a portion of the filling layer.

[0061] In other embodiments of this first variant, a single carcass layer is wound around the circumferential reinforcement element of each bead so that the axially inner portion of the first carcass layer is axially arranged inboard of the axially outer portion of the carcass layer, and each axial end of the carcass layer is radially arranged on the outside of each circumferential reinforcement element, and the portion of the reinforcing layer in contact with the reinforcing layer arranged in the sidewall is formed by a portion of the axially outer portion of the single carcass layer in the sidewall. In these embodiments, the axially outer portion of the carcass layer is relatively long. Therefore, the reinforcing layer is in contact with a portion of the axially outer portion in at least the bead and is in contact with another portion of the axially outer portion in at least the sidewall.

[0062] In other embodiments of this first variant form, each bead comprises at least a first circumferential reinforcing element and a second circumferential reinforcing element, and a portion of the carcass layer is arranged axially between at least two of the first circumferential reinforcing element and the second circumferential reinforcing element, for example as described in WO2021 / 123522.

[0063] In a second variant of the first construction, the carcass reinforcement comprises a first carcass layer and a second carcass layer, each of which is anchored in each bead, extends radially in each sidewall and extends axially in the crown radially on the inside of the crown reinforcement, one of the first carcass layer and the second carcass layer forming a reinforcing layer.

[0064] In certain embodiments of this second variant form, the first carcass layer is wound around the circumferential reinforcement element of each tire bead so that the axially inner portion of the first carcass layer is axially arranged on the inside of the axially outer portion of the first carcass layer, each axial end of the first carcass layer is radially arranged on the outside of each circumferential reinforcement element, and each axial end of the second carcass layer is radially arranged on the inside of each axial end of the first layer.

[0065] In a first alternative form of these embodiments, each axial end of the second carcass layer is axially arranged between the axially inner and axially outer portions of the first carcass layer, the second carcass layer forming a reinforcement layer. In this first alternative form, the reinforcement layer is thus in contact with at least a portion of the axially outer portion of the first carcass layer at least in the bead, and at least a portion of the second carcass layer at least in the sidewall. Optionally, the tire comprises at least a filling layer axially arranged at least between the axially inner and axially outer portions of the first carcass layer and extending radially from the circumferential reinforcement element to the crown of the tire, the reinforcement layer thus also being in contact with at least a portion of the filling layer.

[0066] In a second alternative form of these embodiments, each axial end of the second carcass layer is axially arranged on the inside of each axially inner portion of the first carcass layer, the first carcass layer forming a reinforcing layer. In this second alternative form, the reinforcing layer is therefore in contact with at least a portion of the axially outer portion of the first carcass layer at least in the beads, and at least a portion of the first carcass layer at least in the sidewalls. Optionally, the tire comprises a filling layer axially arranged at least between the axially inner and axially outer portions of the first carcass layer and extending radially from the circumferential reinforcing element to the crown of the tire, the reinforcing layer thus also being in contact with at least a portion of the filling layer.

[0067] In a third alternative of these embodiments, each axial end of the second carcass layer is axially arranged on the outside of each axially outer portion of the first carcass layer, the second carcass layer forming a reinforcing layer. In this third alternative, the reinforcing layer is therefore in contact with at least a portion of the second carcass layer at least in the beads and at least another portion of the second carcass layer at least in the sidewalls.

[0068] In other embodiments of this second variant form, each bead comprises a plurality of circumferential reinforcing elements, at least a portion of each of the first and second carcass layers being axially arranged between at least two circumferential reinforcing elements of the plurality of circumferential reinforcing elements, for example as described in WO 2021 / 123522.

[0069] In a second configuration, the tire comprises:

[0070] a carcass reinforcement comprising at least one carcass layer anchored in each bead, the crown comprising a crown reinforcement, the carcass layer extending radially in each sidewall and extending axially in the crown radially on the inside of the crown reinforcement,

[0071] - sidewall reinforcements arranged axially on the outside of the carcass reinforcement,

[0072] The sidewall reinforcement layers form the reinforcement layers.

[0073] Unlike the carcass layer, which is anchored in each bead, the sidewall reinforcement layer is not anchored in each bead. Therefore, each radially inner end of the sidewall reinforcement layer is arranged radially outside each bead. The sidewall reinforcement layer extends at least radially in each sidewall and has:

[0074] a radially inner end portion arranged radially inside the tire equator, and

[0075] A radially outer end portion arranged radially outside the tire equator.

[0076] In certain embodiments in which a single carcass layer or a first carcass layer forms a winding, each axial end of the carcass layer is arranged radially inboard of the tire equator, and even more preferably at a radial distance of less than or equal to 30 mm from the radially inner end of each circumferential reinforcing element of each bead. By arranging each axial end of the single carcass layer or the first carcass layer inboard of the tire equator, the mass of the carcass reinforcement is significantly reduced. Furthermore, the vast majority of rims currently used for passenger vehicle tires have a J-shaped flange that is less than 30 mm in height in all cases. Arranging each axial end preferably in an area roughly radially corresponding to the rim flange mechanically protects each axial end. Specifically, if each axial end were arranged radially too far above each circumferential reinforcing element of each bead in the sidewall (i.e., at a radial distance significantly greater than 30 mm from the radially inner end of each circumferential reinforcing element), each axial end would be located in a flexible region of the tire subject to excessive stresses. In particular, such stresses are particularly high in tires of high load capacity types.

[0077] In other embodiments in which a single carcass layer or a first carcass layer forms the winding, each axial end of said carcass layer is arranged radially on the outside of the tire equator. Advantageously, in these other embodiments, each axial end of a single carcass layer or a first carcass layer is very preferably arranged axially on the inside of an axial end of said crown layer or of at least one crown layer of the crown reinforcement.

[0078] In some embodiments, the crown comprises a crown reinforcement comprising a working reinforcement comprising a radially inner working layer and a radially outer working layer arranged radially outside the radially inner working layer.

[0079] Optionally, each working layer is axially delimited by two axial ends of said working layer and comprises working reinforcement elements extending axially from one axial end to the other axial end of said working layer and being substantially parallel to each other.

[0080] Optionally, each working reinforcement element extends in a main direction forming an angle with the circumferential direction of the tire having an absolute value strictly greater than 10°, preferably ranging from 15° to 50°, more preferably ranging from 20° to 35°.

[0081] Preferably, in an embodiment in which the working reinforcement comprises a radially innermost working layer and a radially outermost working layer arranged radially outside the radially innermost layer, the main direction of extension of each working reinforcement element of the radially innermost working layer and the main direction of extension of each working reinforcement element of the radially outermost working layer form angles of opposite orientation with the circumferential direction of the tire.

[0082] Optionally, the crown reinforcement comprises a hoop reinforcement axially delimited by two axial ends of the hoop reinforcement and comprising at least one hoop reinforcing element circumferentially helically wound so as to extend axially between the axial ends of the hoop reinforcement.

[0083] Preferably, the hoop reinforcement is arranged radially outside the working reinforcement.

[0084] Preferably, the or each hoop reinforcing element extends in a main direction making an angle with the circumferential direction of the tyre of absolute value less than or equal to 10°, preferably less than or equal to 7°, more preferably less than or equal to 5°. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] The invention will be better understood on reading the following description, given by way of non-limiting example only and with reference to the accompanying drawings, in which:

[0086] - Figure 1 is a view of a meridian cross-sectional plane of a tire according to a first embodiment of the invention,

[0087] - Figure 2 for Figure 1 Detail of one sidewall of the tire,

[0088] - Figure 3 for Figure 1 Detail of one bead and part of a sidewall of a tire,

[0089] - Figures 4 to 10 Respectively Figure 1 Similar views of tires according to the second, third, fourth, fifth, sixth, seventh and eighth embodiments. DETAILED DESCRIPTION

[0090] The figures show reference frames X, Y, Z which correspond to the general axial direction (Y), radial direction (Z) and circumferential direction (X) of the tire or mounting assembly, respectively.

[0091] Figures 1 to 3 A tire according to the present invention is shown, designated by reference numeral 10. Tire 10 has a generally annular shape about an axis of rotation substantially parallel to axial direction Y. Tire 10 is intended for use on passenger vehicles and has a size of 255 / 35R19. In the various figures, tire 10 is shown brand new, i.e., when it has not yet been driven.

[0092] The tire 10 comprises a crown 12 comprising a tread 14 intended to come into contact with the ground when the tire is running, and a crown reinforcement 16 extending in the crown 12 in the circumferential direction X. The tire 10 also comprises an airtight inner liner 18 impermeable to the inflation gas and intended to delimit, together with the mounting support of the tire 10 when the tire 10 is mounted on the mounting support, such as a rim, an internal cavity intended to be pressurized with the inflation gas. The airtight inner liner 18 bears an inner surface 19 of the tire 10.

[0093] The crown reinforcement 16 comprises a working reinforcement 20 and a hoop reinforcement 22. The working reinforcement 20 comprises at least one working layer, in this case two working layers, a radially inner working layer 24 and a radially outer working layer 26 arranged radially to the outside of the radially inner working layer 24.

[0094] The hoop reinforcement 22 comprises at least one hoop layer, in this case one hoop layer 28 .

[0095] The crown reinforcement 16 is arranged radially on the inside of the tread 14 . In this case, the hoop reinforcement 22 , in this case a hoop layer 28 , is arranged radially on the outside of the working reinforcement 20 and is therefore radially interposed between the working reinforcement 20 and the tread 14 .

[0096] The tire 10 comprises two sidewalls 30 which continue radially inwardly from the crown 12. The tire 10 also has two beads 32 which are located radially inwardly of the sidewalls 30. Each sidewall 30 connects each bead 32 to the crown 12. Figure 3 The boundary between each bead 32 and each adjacent sidewall 30 is shown by dashed line D.

[0097] The tire 10 comprises a carcass reinforcement 34. A crown reinforcement 16 is arranged radially between the tread 14 and the carcass reinforcement 34. The carcass reinforcement 34 comprises at least one carcass ply 36, in this case a single carcass ply 36, anchored in each bead 32. The carcass ply 36 extends radially in each sidewall 30 and axially in the crown 12 radially inside the crown reinforcement 16.

[0098] The carcass ply 36 anchored in each bead 32 is wound around the circumferential reinforcing element 33 of each bead 32 so that the axially inner portions 3611, 3621 of the carcass ply 36 anchored in each bead 32 are arranged axially on the inside of the axially outer portions 3612, 3622 of the carcass ply 36 anchored in each bead 32, and each axial end 361, 362 of the carcass ply 36 anchored in each bead 32 is axially arranged radially on the outside of each circumferential reinforcing element 33. Each axial end 361, 362 of a single carcass ply 36 anchored in each bead 32 is arranged radially on the inside of the equator E of the tire. More precisely, each axial end 361, 362 of the carcass ply 36 anchored in each bead 32 is arranged at a radial distance RNC less than or equal to 30 mm from the radially inner end 331 of each circumferential reinforcing element 33 of each bead 32. In this case, RNC=23 mm.

[0099] Each working layer 24, 26, the hoop layer 28 and the carcass layer 36 comprises a polymer matrix (in this case an elastomeric matrix) in which one or more reinforcing elements (in this case filamentous reinforcing elements) of the corresponding layer are embedded. The structure of the various layers and the various reinforcing elements is conventional, for example as described in applications WO2021250331, WO2022074341 or WO2022069819.

[0100] In particular, refer to Figure 2 The axially outermost reinforcing layer in each sidewall 30, in this case a single carcass ply 36, comprises filamentary reinforcing elements 360 embedded in a polymer matrix 363. The filamentary reinforcing elements 360 extend axially from one axial end to the other axial end of the single carcass ply 36 in a main direction forming an angle with the circumferential direction X of the tire 10 having an absolute value greater than or equal to 60°, preferably ranging from 80° to 90°, in this case equal to 90°.

[0101] The carcass layer 36 is separated from the adjacent layers in contact with its polymer matrix 363 by an axially inner interface IAI and an axially outer interface IAE.

[0102] The modulus MA100R of the polymer matrix 363 of the carcass layer 36 at 100% elongation satisfies MA100R≧1.0 MPa, preferably MA100R≧1.5 MPa, and MA100R≦2.5 MPa, preferably MA100R≦2.0 MPa. In this case, MA100R=1.7 MPa.

[0103] Each sidewall 30 bears markings indicating the dimensions of tire 10. In this case, tire 10 has a nominal section width SW equal to 235, a nominal aspect ratio AR equal to 35, and a nominal rim diameter equal to 19. Consequently, the sidewall height H of tire 10, defined by SW×AR / 100, in this case is equal to 82. Tire 10 is an extra-load version with dimensions 235 / 35R19 and has a load index equal to 91, as shown in the 2021 ETRTO Standards Manual, section Passenger Car Tyres - Tyres with Metric Designation, page 38. Tire 10 satisfies 0.72≤H / LI≤1.00, preferably 0.72≤H / LI≤0.95, in which case H / LI = 0.90.

[0104] Reference Figures 1 to 3 Each sidewall 30 comprises an outer layer 42 of said sidewall 30. Each outer layer 42 carries an outer surface 43. The tire 10 comprises a reinforcing layer 44 extending radially from each bead 32 to the sidewall 33 adjacent to each bead 30.

[0105] The tire 10 comprises a filling layer 46 arranged axially at least between an axially inner portion 3611 and an axially outer portion 3612 of the single carcass layer 36 and extending radially from the circumferential reinforcing elements 33 to the crown 12. The tire 10 comprises a seat layer 48 for the tire 10, intended to come into contact with a mounting support of the tire 10, such as a rim, when the tire 10 is mounted on the mounting support.

[0106] In this first embodiment, a single carcass layer 36 forms the reinforcement layer. Thus, in each sidewall 30, each reinforcing layer 44 is axially arranged between the single carcass layer 36 and the outer layer 42 of the sidewall 30. In each sidewall 30, each reinforcing layer 44 is arranged to contact at least a portion of the single carcass layer 36. In each sidewall 30, each reinforcing layer 44 is arranged to contact at least a portion of the outer layer 42.

[0107] Therefore, the portion of the reinforcing layer in contact with the reinforcing layer 44 arranged in each sidewall 30 is formed by a portion of each axially inner portion 3611, 3621 of the single carcass layer 36 in each sidewall 30. In addition, the reinforcing layer 44 is in contact with a portion of each axially outer portion 3612, 3622 in each bead 32, and is in contact with a portion of the axially inner portion 3611, 3612 in each sidewall 30. Therefore, the reinforcing layer 44 is also in contact with a portion of the filling layer 46.

[0108] Specifically, the modulus MA10B of the reinforcing layer 44 at 10% elongation satisfies MA10B≧30.0 MPa, preferably MA10B≧40.0 MPa, and more preferably 40.0 MPa≦MA10B≦70.0 MPa. In this case, MA10B=48 MPa.

[0109] The polymer matrix of the axially outermost reinforcing layer (in this case, the single carcass layer 36) in contact with the reinforcing layer 44 arranged in each sidewall 30 is such that the ratio R=MA100R / MA10B satisfies R×1000≥(0.011×MA10B×MA10B)−1.71×MA10B+86.70, preferably R×1000≥(0.0106×MA10B×MA10B)−1.72×MA10B+90.40. Furthermore, R preferably satisfies R×1000≤(0.0127×MA10B×MA10B)−2.03×MA10B+109. In this case, 1000×R=35.42.

[0110] Now we will refer to Figures 4 to 10 Tires according to a second embodiment, a third embodiment, a fourth embodiment, a fifth embodiment, a sixth embodiment, a seventh embodiment and an eighth embodiment are described. Elements similar to those shown in the preceding figures are denoted by the same reference numerals.

[0111] Unlike the tire according to the first embodiment, Figure 4 Each bead 32 of the tire 10 of the second embodiment comprises at least a first circumferential reinforcing element 50 and a second circumferential reinforcing element 52. A portion of the single carcass layer 36 is axially arranged between the first circumferential reinforcing element 50 and the second circumferential reinforcing element 52.

[0112] Unlike the tire according to the first embodiment, in the tire according to Figure 5In the tire 10 of the third embodiment shown, each axial end 361, 362 of the carcass ply 36 anchored in each bead and forming a winding is arranged radially outside the equator E and even more preferably axially inside the axial ends of the working layers 24 and the hoop layers 28 of the crown reinforcement 16. In this third embodiment, the portion of the reinforcing layer in contact with the reinforcing layer 44 arranged in each sidewall 30 is formed by a portion of each axially outer portion 3612, 3622 of a single carcass ply 36 in each sidewall 30. The reinforcing layer 44 is in contact with a portion of each axially outer portion 3612, 3622 of the bead 32 and with another portion of the axially outer portion 3612, 3612 in each sidewall 30.

[0113] Unlike the tire according to the first embodiment, Figure 6 The carcass reinforcement 34 of the tire 10 of the fourth embodiment comprises a first carcass layer 36 and a second carcass layer 37 anchored in each bead 32. The first carcass layer 36 is wound around each circumferential reinforcing element 33 of each bead 32 so that an axially inner portion 3611, 3621 of the first carcass layer 36 is axially arranged on the inside of an axially outer portion 3612, 3622 of the first carcass layer 36, and each axial end 361, 362 of the first carcass layer 36 is radially arranged on the outside of each circumferential reinforcing element 33. Each axial end 371, 372 of the second carcass layer 37 is radially arranged on the inside of each axial end 361, 362 of the first layer and axially arranged between the axially inner portion 3611, 3621 and the axially outer portion 3612, 3622 of the first carcass layer 36. In this case, the second carcass layer 37 forms a reinforcing layer in contact with the arranged reinforcing layer 44. The reinforcing layer 44 contacts a portion of the axially outer portion 3612, 3622 of the first carcass layer 36 in each bead 32 and a portion of the second carcass layer 37 in each sidewall 30. The reinforcing layer 44 also contacts a portion of the filling layer 46.

[0114] Unlike the tire according to the fourth embodiment, in the tire according to Figure 7 In the tire 10 of the fifth embodiment shown, each axial end portion 371, 372 of the second carcass layer 37 is arranged axially inwardly of each axially inner portion 3611, 3621 of the first carcass layer 36. In this case, the first carcass layer 36 forms a reinforcement layer that is in contact with the arranged reinforcing layer 44. The reinforcing layer 44 is in contact with a portion of each axially outer portion 3612, 3622 of the first carcass layer 36 in each bead 32, and is in contact with a portion of the first carcass layer 36 in each sidewall 30. The reinforcing layer 44 is also in contact with a portion of the filling layer 46.

[0115] Unlike the tire according to the fourth embodiment, in the tire according to Figure 8In the tire 10 of the sixth embodiment shown, each axial end portion 371, 372 of the second carcass layer 37 is axially arranged outside each axially outer portion 3612, 3622 of the first carcass layer 36. In this case, the second carcass layer 37 forms a reinforcing layer. The reinforcing layer 44 contacts a portion of the second carcass layer 37 in each bead 32 and contacts another portion of the second carcass layer 37 in each sidewall 30.

[0116] Unlike the tire according to the fourth embodiment, in the tire according to Figure 9 In the tire 10 of the seventh embodiment shown, each bead 32 comprises a plurality of circumferential reinforcing elements 50, 52. At least a portion of each of the first and second carcass layers 36, 37 is axially arranged between two of the plurality of circumferential reinforcing elements 50, 52.

[0117] Unlike the tire according to the first embodiment, in the tire according to Figure 10 In the tire 10 of the eighth embodiment shown, the tire 10 comprises two sidewall reinforcement layers 39 arranged axially on the outside of the carcass reinforcement 34. Each sidewall reinforcement layer 39 extends radially at least in each sidewall 30 and has a radially inner end 391 arranged radially on the inside of the equator E and a radially outer end 392 arranged radially on the outside of the equator E. Each radially inner end 391 of each sidewall reinforcement layer 39 is arranged radially on the outside of each bead 32 and is therefore not anchored therein. In this case, the sidewall reinforcement layers 39 form a reinforcing layer.

[0118] Comparative testing

[0119] The two tires were run in a running test similar to the load / speed performance test described in Annex VII of UNECE Regulation No. 30 (but under even more severe conditions). The two tires were constructed similarly to the reference Figure 6 The construction of the tire of the fourth embodiment is described. These two tires comprise identical reinforcing layers having a modulus MA10B at 10% elongation equal to 48 MPa.

[0120] A first control tire not according to the invention had dimensions 235 / 35R19 and comprised a first carcass layer whose polymer matrix had a modulus MA100R at 100% elongation equal to 1.2 MPa, resulting in a value of 1000×R equal to 25.00, which is below the threshold of the invention (calculated to be 29.96).

[0121] A second tire according to the invention has the same dimensions 235 / 35R19 and comprises a first carcass layer whose polymer matrix has a modulus MA100R at 100% elongation equal to 1.6 MPa, resulting in a value of 1000×R equal to 33.33, which is above the threshold of the invention (calculated to be 29.96).

[0122] The composition of the corresponding polymer matrix is described in the table below. The compositions were prepared under conventional compounding conditions and vulcanized under conditions likewise conventional in the tire sector, in this case at between 160° and 165° for 15 minutes.

[0123]

[0124]

[0125] (1) - natural rubber; (2) - SBR with 26% of styrene units, 24% of vinyl units and 47% of 1-4 trans units, Tg: -54°C; (3) and (4) - ASTM grade carbon black according to standard D-1765; (5) - high-quality rubber processing oil (Vivatec 500); (6) - N-cyclohexyl-benzothiazolesulfenamide (Santocure CBS from Flexsys); (7) - N-tert-butyl-2-benzothiazolesulfenamide (sold by Flexsys); (8) - zinc oxide (technical grade - sold by Umicore); (9) - stearin ("Pristerene 4931" sold by Uniqema); (10) N-1,3-dimethylbutyl-N-phenyl-p-phenylenediamine (Santoflex 6-PPD sold by Flexsys).

[0126] After 31,000 km of travel on a rolling road machine, the control tire showed clear signs of heating of the interface between the reinforcement layer and the first carcass layer. The tire according to the invention did not show any signs of abnormal heating of this same interface.

[0127] The present invention is not limited to the embodiments described above.

[0128] In particular, as described above, the present invention can be advantageously applied to tires of the high load capacity type. For such tires, the marking includes a load index LI satisfying LI≥LI'+1, where LI' is the load index of an extra load tire of the same size according to the 2021 ETRTO standard manual. Preferably, LI'+1≤LI≤LI'+4, and even LI'+2≤LI≤LI'+4. As described above, the extra load version of the tire with a size of 235 / 35R19 has a load index equal to 91. Therefore, the load index LI of the high load capacity version of the tire with a size of 235 / 35R19 satisfies LI≥92, preferably 92≤LI≤95, even 93≤LI≤95, in which case LI=94. The high load capacity version of the tire satisfies 0.72≤H / LI≤1.00, preferably 0.72≤H / LI≤0.95, in which case H / LI=0.88.

Claims

1. A tire (10) for a passenger vehicle, the tire (10) comprising: a crown (12), two beads (32), two sidewalls (30) connecting each bead (32) to the crown (12), each sidewall (30) comprising an outer layer (42) of said sidewall (30) carrying an outer surface (43) of said sidewall (30), a reinforcing layer extending radially in at least one sidewall (30) and comprising filamentary reinforcing elements (360) embedded in a polymer matrix (363), a reinforcing layer (44) extending radially from one bead (32) to a sidewall (30) adjacent to said bead (32), wherein in said sidewall (30) said reinforcing layer (44): - axially arranged between the reinforcing layer and the outer layer (42) of said sidewall (30), and - in contact with at least a portion of the reinforcing layer and with at least a portion of the outer layer (42) of said sidewall (30), It is characterized in that the ratio R of the modulus MA100R of the polymer matrix (363) of the reinforcing layer at 100% elongation to the modulus MA10B of the reinforcing layer (44) at 10% elongation satisfies R×1000≥(0.011×MA10B×MA10B)-1.71×MA10B+86.

70.

2. Tyre (10) according to the preceding claim, wherein R×1000≥(0.0106×MA10B×MA10B)-1.72×MA10B+90.

40.

3. Tyre (10) according to any one of the preceding claims, wherein R×1000≤(0.0127×MA10B×MA10B)-2.03×MA10B+109.

4. Tyre (10) according to any one of the preceding claims, wherein MA10B≥30.0 MPa, preferably MA10B≥40.0 MPa, more preferably 40.0 MPa≤MA10B≤70.0 MPa.

5. Tyre (10) according to any one of the preceding claims, wherein MA100R≥1.0 MPa, preferably MA100R≥1.5 MPa.

6. Tyre (10) according to any one of the preceding claims, wherein MA100R≤2.5 MPa, preferably MA100R≤2.0 MPa.

7. Tyre (10) according to any one of the preceding claims, being of the high load capacity type according to the ETRTO Manual of Standards 2021.

8. The tire (10) according to any one of the preceding claims, wherein the sidewall height H of the tire (10) is defined by H=SW×AR / 100, wherein SW is the nominal section width of the tire, AR is the nominal aspect ratio of the tire, and the load index LI satisfies H / LI≤1.00, preferably 0.72≤H / LI≤1.00, and more preferably 0.72≤H / LI≤0.95, wherein SW, AR and LI are defined according to the ETRTO standard manual of 2021.

9. A tyre (10) according to any one of the preceding claims, comprising a carcass reinforcement (34), the carcass reinforcement (34) comprising at least one carcass layer anchored in each bead (32), the crown (12) comprising a crown reinforcement (16), the at least one carcass layer (34) extending radially in each sidewall (30) and extending axially in the crown (12) radially inside the crown reinforcement (16), the at least one carcass layer (34) forming a reinforcement layer.

10. The tire (10) according to claim 9, wherein The carcass reinforcement (34) comprises a single carcass layer (36) anchored in each bead (32), extending radially in each sidewall (30) and extending axially in the crown (12) radially inside the crown reinforcement (16), the single carcass layer forming a reinforcing layer.

11. Tyre (10) according to the preceding claim, wherein The single carcass layer (36) is wound around the circumferential reinforcing element (33) of each bead (32) so that the axially inner portion (3611, 3621) of the first carcass layer (36) is axially arranged on the inside of the axially outer portion (3612, 3622) of the carcass layer (36), and each axial end portion (361, 362) of the carcass layer (36) is radially arranged on the outside of each circumferential reinforcing element (33): - the portion of the reinforcing layer in contact with the reinforcement layer (44) arranged in the sidewall (30) is formed by a portion of the axially inner portion of a single carcass layer (36) in the sidewall (30), or The portion of the reinforcing layer in contact with the reinforcement layer (44) arranged in the sidewall (30) is formed by a portion of the axially outer portion of the single carcass layer (36) in the sidewall (30).

12. The tire (10) according to claim 9, wherein: The carcass reinforcement comprises a first carcass layer and a second carcass layer (36, 37), each of which is anchored in each bead (32), extends radially in each sidewall (30) and extends axially in the crown (12) radially inside the crown reinforcement (16), one of which forms a reinforcing layer.

13. Tyre (10) according to the preceding claim, wherein The first carcass layer (36) is wound around the circumferential reinforcing element (33) of each bead (32) so that the axially inner portion (3611, 3621) of the first carcass layer (36) is axially arranged inside the axially outer portion (3612, 3622) of the first carcass layer (36), and each axial end (361, 362) of the first carcass layer (36) is radially arranged outside each circumferential reinforcing element (33), and each axial end (371, 372) of the second carcass layer (37) is radially arranged inside each axial end (361, 362) of the first layer (36), and: - axially located between the axially inner portion (3611, 3621) and the axially outer portion (3612, 3622) of the first carcass layer (36), said second carcass layer (37) forming a reinforcement layer, or - axially inside each axially inner portion (3611, 3621) of a first carcass layer (36) forming a reinforcing layer, or - Axially outside each axially outer portion (3612, 3622) of the first carcass layer (36), said second carcass layer (37) forms a reinforcement layer.

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