WO2020094979A1

WO2020094979A1 - Device of pneumatic tyre type with flexible filamentary elements, for a vehicle

Info

Publication number: WO2020094979A1
Application number: PCT/FR2019/052630
Authority: WO
Inventors: Matthieu Bonnamour
Original assignee: Compagnie Generale Des Etablissements Michelin
Priority date: 2018-11-09
Filing date: 2019-11-06
Publication date: 2020-05-14

Abstract

The present invention relates to a device (1) of the pneumatic tyre type, intended to be fitted to a vehicle, comprising a load-bearing assembly (8) providing an improvement in flattening, and with the objective of reducing the cabin noise generated. A device (1) of the pneumatic tyre type according to the invention essentially comprises two coaxial structures exhibiting symmetry of revolution, these respectively being a radially outer structure (2) and a radially inner structure (3), which are separated radially by an annular interior space (5), connected to one another, in a running zone, by a load-bearing assembly (8) made up of a load-bearing structure (6) comprising filamentary load-bearing elements (61), a radially outer connecting structure (71) and a radially inner connecting structure (72), and are connected to one another, at their respective axial ends (24, 34) by two sidewalls (9), themselves reinforced by a carcass reinforcement (10, 11). According to the invention, the equivalent tangent modulus of stiffness in extension E of the load-bearing assembly (8) is at most equal to 1 MPa.

Description

Pneumatic type device with flexible wire elements for vehicle.

The present invention relates to a pneumatic type device, intended to equip a vehicle. This pneumatic type device is preferably designed for passenger vehicles, but can a priori be used on any other type of vehicle such as two-wheeled vehicles, heavy vehicles, agricultural, civil engineering or airplanes or, more generally, on any rolling device.

A conventional tire is a toric structure, intended to be mounted on a rim, pressurized by an inflation gas and crushed on a ground under the action of a load. The tire has at every point of its rolling surface, intended to come into contact with a ground, a double curvature: a circumferential curvature and a meridian curvature. By circumferential curvature is meant a curvature in a circumferential plane, defined by a circumferential direction, tangent to the rolling surface of the tire in the rolling direction of the tire, and a radial direction, perpendicular to the axis of rotation of the tire. By meridian curvature is meant a curvature in a meridian or radial plane, defined by an axial direction, parallel to the axis of rotation of the tire, and a radial direction, perpendicular to the axis of rotation of the tire.

In what follows, the expression “radially interior, respectively radially exterior” means “closer, respectively farther from the axis of rotation of the tire”. The expression “axially interior, respectively axially exterior” means “closer, respectively farther from the equatorial plane of the tire”, the equatorial plane of the tire being the plane passing through the middle of the tire rolling surface and perpendicular to the axis of rotation of the tire.

It is known that the flattening of the tire on a horizontal ground, in a circumferential plane and in a meridian plane, is conditioned by the values of the radii of curvature, respectively circumferential and meridian, at the points of the surface of bearing positioned at the limits of the tire's contact area with the ground. This flattening is all the easier when these radii of curvature are large, that is to say that the curvatures are small, the curvature at a point, in the mathematical sense, being the inverse of the radius of curvature. It is also known that the flattening of the tire impacts the performance of the tire, in particular rolling resistance, grip, wear and noise. Consequently, a person skilled in the art, a specialist in tires, seeking to obtain the right compromise between the expected performance of the tire such as, in a non-exhaustive manner, wear, grip, endurance, resistance rolling and noise, has developed alternative solutions to conventional tires to optimize its flattening.

A conventional tire of the prior art generally has a large meridian curvature, that is to say a small meridian radius of curvature, at the axial ends of the tread, called shoulders, when the pneumatic, mounted on its mounting rim and inflated to its recommended operating pressure, is subject to its service load. The mounting rim, working pressure and service load are defined by standards, such as, for example, the standards of the European Tire and Rim Technical Organization (ETRTO). A conventional tire carries the load applied, essentially by the axial ends of the tread, or shoulders, and by the sidewalls connecting the tread to beads ensuring the mechanical connection of the tire with its mounting rim. It is known that a meridian flattening of a conventional tire, with a small meridian curvature at the shoulders, is generally difficult to obtain.

Document WO 2017005713 A1 proposes a device of the pneumatic type with improved flattening of its tread compared to a conventional tire, when it is subjected to a load. This pneumatic type device comprises a radially external structure of revolution, intended to come into contact with a ground, a radially interior structure of revolution, intended to come into contact with a mounting means, two sides connecting these two structures together. revolution and delimiting an interior annular space, and a load-bearing structure constituted by identical load-bearing elements which, when the tire is subjected to a load, are extended outside the area of contact of the tire with the ground and in compression in the 'contact area, and two sides. The supporting elements are fixed and are connected respectively to the radially inner face of the radially outer structure of revolution by a radially outer fabric and to the radially outer face of the radially inner structure of revolution by a radially inner fabric, so that the he assembly consisting of the supporting structure, the radially outer fabric and the radially inner fabric constitutes a sandwich structure. In addition, the average surface density D of the load-bearing elements per unit area of the radially outer structure of revolution, expressed in l / m ² , is at least equal to (S / S _| ) * Z / (A * F ₁ ), where S is the surface, in m ² , of the radially inner face of the radially outer structure of revolution, S _E is the connecting surface, in m ² , of the radially outer fabric with the radially inner face of the radially outer structure of revolution, Z is the nominal radial load, in N, A is the surface of contact with the ground, in m ² , and F _r the breaking force , in N, of a carrier element.

The document WO 2018020164 A1 is an improvement of the pneumatic type device described in the document WO 2017005713 A1 previously described, with a further improved flattening of its tread compared to a conventional tire, when it is subjected at a charge. This document describes in particular strand bearing elements of the bearing structure having an initial length L _P strictly greater than the mean radial height H and at most equal to 1.1 times the mean radial height H of the interior annular space, defined as the distance between the radially inner face of the radially outer structure of revolution and by the radially outer face of the radially inner structure of revolution. This distance H is measured on the pneumatic type device in its initial state, that is to say mounted on its mounting means, inflated to a recommended pressure but not subjected to a load Z. The recommended pressure may if necessary be zero: in this case, the tire is uninflated and supports the load only by its structure. An initial length Lp of carrier element strictly greater than the average radial height H implies that any carrier element is relaxed in the initial state of the pneumatic type device. When the pneumatic type device is subjected to the load Z, the load-bearing elements, out of contact with the ground, tend, and at least some of them become rectilinear, because the mean radial height increases outside Make contact, due to the appearance of a counter-arrow. On the other hand, the supporting elements in Make contact remain relaxed. The elongation of the load-bearing elements allows greater radii of curvature in any circumferential plane, at the entry and exit of the contact area, and therefore facilitates the circumferential flattening of the pneumatic type device. On the other hand, if the initial length L _P of the load-bearing element was greater than 1.1 times the average radial height H, any load-bearing element would remain relaxed and the load-bearing structure could not fulfill its load-bearing function.

The document WO 2017103490 A1 describes an advantageous embodiment of the sandwich structure constituted by the support structure, the radially outer fabric and the radially inner fabric of the pneumatic type device described in the document WO 2017005713 A1. This document describes a sandwich structure, constituted by an assembly comprising a first woven or knitted structure impregnated comprising a first fabric or knitted fabric and a first layer of a first polymeric composition, a second woven or knitted structure impregnated comprising a second fabric or knitting and a second layer of a second polymeric composition, a carrying structure comprising carrying elements connecting the first and second fabrics or knits together and at least one sacrificial means for temporarily holding the first and second woven or knitted structures impregnated one with respect to the other, connecting the first and second fabrics or knits to each other, the sacrificial means being arranged so as to break before the load-bearing elements when the first and second woven or knitted structures impregnated are removed from one 'other.

As described in document WO 2017005713 A1, the support structure, the radially outer fabric and the radially inner fabric, constituting the sandwich structure, can be made up of various types of materials:

-polymeric materials, such as an aliphatic polyamide, for example nylon, an aromatic polyamide, for example aramid, or a polyester, for example a polyethylene terephthalate (PET),

-metallic materials, such as steel,

-or glass or carbon type materials or any combination of the previous materials.

The inventors have however found that with a support structure constituted by some of the materials mentioned above, such as, for example, a polyester of polyethylene terephthalate (PET) type, the pneumatic type device could generate a level of interior noise degraded compared to a standard tire. The interior noise is here defined by a noise at low frequencies, perceived inside a vehicle driving on a ground with high granularity, the frequencies being between 80 Hz and 800 Hz. Consequently, certain materials constituting the load-bearing elements the supporting structure is not suitable for the internal noise generated.

The present invention therefore aims to provide a device of the type

tire for vehicle with a supporting structure allowing an improvement of the flattening, with a reduction of the internal noise generated.

This object was achieved, according to the invention, by a pneumatic type device, intended to equip a vehicle, comprising: a radially outer structure of revolution whose axis of revolution is the axis of rotation of the pneumatic type device and intended to come into contact with a ground by means of a tread comprising at least one elastomeric material, the radially outer structure of revolution having two axial ends and a radially inner face, and the radially outer structure of revolution comprising a circumferential reinforcement,

a radially interior structure of revolution, coaxial with the radially exterior structure of rotation and intended to ensure the connection of the pneumatic type device with a mounting means on the vehicle, the radially interior structure of revolution having two axial ends and a radially facing exterior, and the radially interior structure of revolution comprising at least one polymeric material,

an interior annular space radially delimited by the radially interior face of the radially exterior structure of revolution and by the radially exterior face of the radially interior structure of revolution,

-two sidewalls, connecting two by two the axial ends of the structures of revolution respectively radially exterior and radially interior and axially delimiting the interior annular space,

a carcass reinforcement extending radially in each sidewall and axially at least partly in the radially outer structure of revolution and at least partly in the radially interior structure of revolution,

-a supporting structure constituted by a plurality of identical supporting wire elements, each having a medium section Sp, not interconnected in the inner annular space and extending continuously from a radially outer connecting structure, having a surface S _E and secured to the radially inner face of the radially outer structure of revolution, up to a radially inner connecting structure, having a surface Si and secured to the radially outer face of the structure of radially inner revolution, so that, when the pneumatic type device is inflated to a nominal pressure P and crushed under a nominal radial load Z on a ground, at least part of the load-bearing elements, connected to the portion of the radially outer structure of revolution not in contact with the ground, are in tension,

the supporting structure, the radially outer connecting structure and the radially inner connecting structure constituting a carrying assembly,

-the bearing assembly having an equivalent tangent modulus of rigidity in extension E _and and a equivalent secant modulus of rigidity in extension E _es , respectively defined for the value of the radial extension of the carrier assembly, diametrically opposite the contact area, achieved when the pneumatic type device is inflated to a nominal pressure P and crushed under a nominal radial load Z,

the equivalent tangent modulus of rigidity in extension E _and of the bearing assembly being at most equal to 1 MPa.

A pneumatic type device according to the invention thus essentially comprises two coaxial structures of revolution, respectively radially exterior and radially interior, separated radially by an interior annular space and connected together, in the current zone, by a support assembly and, at their respective axial ends, by two flanks, themselves reinforced by a carcass reinforcement.

The radially outer structure of revolution is intended to come into contact with a ground by means of a tread comprising at least one elastomeric material and comprises a circumferential reinforcement reinforcing contributing to the resumption of inflation forces and road holding of the pneumatic type device.

The radially inner revolution structure, coaxial with the radially outer revolution structure, is intended to ensure the connection of the pneumatic type device with a mounting means on the vehicle, such as a rim, and comprises at least one polymeric material, most often elastomeric.

The pneumatic type device also comprises two sidewalls, connecting two by two the axial ends of the structures of revolution respectively radially exterior and radially interior and axially delimiting the interior annular space. Consequently, the interior annular space constitutes a closed cavity which can be pressurized by an inflation gas. The sidewalls, according to their design and, in particular, according to their structural rigidity, can participate more or less in carrying the applied radial load. The sidewalls generally comprise at least one elastomeric material and most often a reinforcing reinforcement. The sides may or may not be directly linked to the supporting structure. If they are not directly linked to the supporting structure, the sidewalls have an autonomous mechanical behavior, without affecting the proper mechanical functioning of the supporting structure. In addition, in combination with the two structures of revolution respectively radially exterior and radially interior, they close the interior annular space which then constitutes a closed cavity which can be pressurized or not by an inflation gas. In the case of effective pressurization by an inflation gas, the pneumatic type device then has pneumatic rigidity, due to the pressure, which will also contribute to the carrying of the applied radial load. Usually, for use on a passenger vehicle, the inflation pressure is at least equal to 0.5 bar, preferably at least equal to 1 bar. The higher the pressure, the greater the contribution of the pneumatic rigidity to the carrying of the applied radial load. In the absence of pressurization and in the case of low structural rigidity of the sidewalls, subject to sufficient circumferential rigidity of the reinforcement reinforcement included in the radially outer structure of revolution, the carrier assembly ensures almost entire load bearing, the sides only playing a protective role against possible attack by elements external to the pneumatic device.

In the case of a device operating with a pressurized cavity, the nominal load is equal to 80% of the maximum load as defined by ETRTO, for example in the document entitled "ETRTO - STANDARDS MANU AL - 2018 " The maximum load depends on the dimensions of the tire and its standard or reinforced version. In the case of a device operating in the absence of pressure, the nominal load is the nominal load as defined above of a device operating with a pressurized cavity of the same dimensions in its standard version. Obviously, by in the absence of pressure, it will be understood that the pressure in the cavity is equal to atmospheric pressure.

In the case of a device operating with a pressurized cavity, the nominal pressure is equal to 2.1 bars for a tire in its standard version and equal to 2.5 bars for a tire in its reinforced version, and this whatever its size. Obviously, in the case of a device operating in the absence of pressure, the nominal pressure is equal to atmospheric pressure.

The pneumatic type device also comprises a carcass reinforcement extending radially in each sidewall and axially at least partially in the radially outer structure of revolution and at least partially in the radially interior structure of revolution. The carcass reinforcement, positioned in each flank, contributes to the resumption of forces and the limitation of deformations, which generate the internal pressure, at the flanks. This contribution requires a mechanical anchoring of said carcass reinforcement with respect to the respectively radially exterior and radially interior structures of revolution: this is the reason why the carcass reinforcement, extending radially in each sidewall, extends axially at least partly in the radially outer structure of revolution and at least partly in the radially interior structure of revolution. In the absence of this carcass reinforcement reinforcing the flanks, the mechanical resistance of the flanks to pressure would be weaker, and their excessive deformations. The term “carcass reinforcement” preferably means a reinforcing reinforcement comprising at least one carcass layer formed by reinforcements coated in an elastomeric mixture. Most often, such a carcass reinforcement comprises a single carcass layer, but it can also be constituted by two superposed carcass layers, the respective reinforcements of which are crossed from one layer to the next.

The operating principle of a pneumatic type device according to the invention is to carry a radial load applied to the pneumatic type device, at least in part by means of a load-bearing structure, made up of load-bearing elements not interconnected in the interior annular space and at least a portion of them, positioned outside the contact area of the pneumatic type device with the ground, are tensioned. The carrier elements positioned in the contact area may or may not be tensioned, under the action of the radial load, depending on the level of the pre-tension possibly applied to the carrier elements during the manufacture of the pneumatic type device, of its mounting on a mounting means and / or its inflation.

The support structure is constituted by a plurality of identical support elements, that is to say, whose geometric characteristics and the constituent materials are identical.

In addition, the carrier elements are not interconnected, that is to say two to two independent, in the interior annular space. In other words, the supporting elements are not mechanically linked to each other in the interior annular space, so that they have independent mechanical behaviors. For example, they are not linked together to form a network or a trellis.

Finally, each carrier element extends continuously from a radially outer connecting structure, having a surface S _E and secured to the radially inner face of the radially outer structure of revolution, to a connecting structure radially interior, having a surface Si and integral with the radially exterior face of the radially interior structure of revolution. In other words, each load-bearing element extends along a generally rectilinear trajectory comprising a first end connected to the radially external connection structure and a second end connected to the radially internal connection structure. Generally, the load-bearing elements are not directly linked to the radially outer and radially inner structures of revolution, but are interfaced with them by means of connecting structures. These connecting structures are most often joined to the corresponding structures of revolution by vulcanization, by gluing or any other fixing method. These connecting structures can be, for example, constituted by woven fabrics. These connecting structures can if necessary be integrated into the corresponding structures of revolution, for example in the case of the anchoring of the ends of the load-bearing elements in the structures of revolution.

The load-bearing elements of the load-bearing structure are moreover stranded, that is to say one-dimensional elements assimilated to wires.

More specifically, each carrier element can be characterized geometrically by its length L _P and by its average section Sp, which is the average of the sections obtained by cutting the carrier element by all the cylindrical surfaces, coaxial with the two structures of revolution radially exterior and radially exterior respectively, and radially between said two structures of revolution. In the most frequent case of a constant section of the carrier element, the mean section Sp is equal to this constant section. The mean section Sp of the carrier element is characterized by a larger characteristic dimension L and a smaller characteristic dimension E, the ratio K = L / E of which is called the aspect ratio. By way of example, a circular average section Sp, having a diameter equal to d, has an aspect ratio K = l, a rectangular average section Sp, having a length L and a width 1, has an aspect ratio K = L / l, and an elliptical middle section Sp, having a large axis A and a small axis a, has an aspect ratio K = A / a.

By definition, a load-bearing element is said to be linear or one-dimensional when the smallest characteristic dimension E of its mean section Sp is at most equal to 0.02 times the mean radial height at rest H ₀ of the interior annular space, and when the aspect ratio K of its mean section Sp is at most equal to 3. The average radial height at rest Ho of the interior annular space is the distance between the radially interior face of the radially exterior structure of revolution and the radially face outside of the radially inner structure of revolution, measured on the non-inflated pneumatic type device. A smaller characteristic dimension E of the medium section Sp of the element carrier at most equal to 0.02 times the average radial height at rest H ₀ of the interior annular space excludes any massive carrier element having a large volume. In other words, each load-bearing element has a high slenderness, in the radial direction. A form ratio K of its mean section Sp at most equal to 3 means that the largest characteristic dimension L of its mean section Sp is at most equal to 3 times the smallest characteristic dimension E of its mean section Sp.

A supporting wire element has a mechanical behavior of the wire type, that is to say that it can only be subjected to extension or compression forces along its mean line. Among the components commonly used in the tire field, the textile reinforcements, constituted by an assembly of textile yarns, or the metal cables, constituted by an assembly of metallic threads, can be considered as load-bearing elements, because their average section Sp being substantially circular, the aspect ratio K is equal to 1, therefore less than 3.

The strand carrying elements may be radial, that is to say form a zero angle with a radial direction perpendicular to the axis of rotation of the tire. In this case, the supporting wire elements are perpendicular to the two structures of revolution respectively radially exterior and radially interior and have lengths Lp which can be between 0.5 times and 1.1 times the average radial height H of the interior annular space. The average radial height H of the interior annular space is the distance between the radially interior face of the radially exterior structure of revolution and the radially exterior face of the radially interior structure of revolution, measured on the pneumatic type device mounted and inflated to a nominal pressure P. However, the supporting elements can also form a non-zero angle with a radial direction.

The assembly constituted by the support structure and the two connecting structures respectively radially exterior and radially interior, called support assembly, is a sandwich structure similar to a composite material. This composite material can be characterized mechanically by a constitutive law representing the evolution of the stress in extension, applied to the composite material in a direction normal to the connection structures, according to its deformation in extension or elongation. This behavior law can typically be determined by a static tensile test on a test piece constituted by a sample of the sandwich structure, comprising the structure carrier connected to the two connecting structures. The tensile specimen used has the form of a thick hollow circular cylinder having an internal diameter equal to 38 mm and an external diameter equal to 60 mm, each end of said cylinder being fixed by gluing to a hollow disc having an internal diameter equal to 26 mm and an outside diameter equal to 70 mm. The tensile test is carried out at imposed deformation with a tensile speed of 200 mm / min. At any point in the constitutive law thus obtained, it is known to determine an equivalent tangent modulus of rigidity in extension E _and and an equivalent secant modulus of rigidity in extension E _es . The equivalent tangent modulus of rigidity in extension E _and is the slope of the line tangent to the law of behavior at the point considered. The equivalent secant modulus of rigidity in extension E _es is the slope of the line passing through the origin of the reference frame and the point considered of the law of behavior. The inventors have chosen to determine, for the bearing assembly, an equivalent tangent modulus of rigidity in extension E _and and an equivalent secant modulus of rigidity in extension E _es , for the value of radial extension of the bearing assembly, diametrically to opposite of the contact area, reached when the pneumatic type device is inflated to a nominal pressure P and crushed under a nominal radial load Z.

According to the invention, the equivalent tangent modulus of rigidity in extension E _and of the carrier assembly is at most equal to 1 MPa.

The inventors have in fact shown that the noise level generated by the pneumatic type device is generally correlated to the equivalent tangent modulus of rigidity in extension E _and of the carrier assembly. More specifically, for a pneumatic type device corresponding to a conventional dimension for a passenger vehicle, for example of the 255/35 R 19 type, the noise level is an increasing non-linear function of the equivalent tangent modulus of rigidity in extension E _and of the carrier assembly, with strong growth below 1 MPa, weaker growth between 1 MPa and 2 MPa, to reach an almost constant maximum level above 2 MPA. Consequently, the inventors fixed at 1 MPa the threshold of equivalent tangent modulus of rigidity in extension E _and of the load-bearing assembly, below which the noise level is considered to be acceptable.

In fact, a tangent modulus of rigidity in extension E _and of the sufficiently small carrier assembly gives the carrier assembly a flexibility making it possible to significantly dampen the transmission of rolling vibrations from the pneumatic type device to the wheel, and thus reduce the interior noise in the vehicle. The equivalent tangent modulus of rigidity in extension E _and of the carrier assembly is therefore considered to be a relevant parameter with regard to the generation of noise. It is defined for the value of the radial extension of the carrier assembly, diametrically opposite the contact area, reached when the pneumatic type device is inflated to a nominal pressure P and crushed under a nominal radial load Z The deformation of the support assembly under the action of a tensile force applied perpendicular to the connecting structures is called radial extension of the support assembly. The nominal pressure P and the nominal radial load Z are recommended values, as defined for example by the ETRTO standards. As described above, this equivalent tangent modulus of rigidity in extension can be determined, in a known manner, from the constitutive law in extension of the bearing assembly obtained by a test of static traction on test piece: it is the slope of the line tangent to the law of behavior at the point considered.

The equivalent tangent modulus of rigidity in extension E _and of the carrier assembly is a function of the tangent modulus of rigidity in extension E _t of each wire bearing element, but also modules of rigidity in extension of the connecting structures as well as rigidities of the interfaces between the supporting wire elements and the connecting structures. The tangent modulus of rigidity in extension E _t of each wire support element is defined for the elongation value of the wire support element reached when the pneumatic type device is inflated to a nominal pressure P and crushed under a nominal radial load Z .

The equivalent tangent modulus of rigidity in extension E _and of the load-bearing assembly is also a function of the surface density D of stranded load elements, defined as the ratio between the sum of the average sections Sp of the stranded load elements and the average arithmetic S _M of the surface S _E of the radially exterior connection structure and of the surface Si of the radially interior connection structure. For given characteristics of strand bearing elements, in terms of geometry and material, the equivalent tangent modulus of rigidity in extension E _and of the bearing assembly is an increasing function of the surface density D of strand bearing elements.

In the particular case where the strand carrying elements are radial, that is to say, are perpendicular to the connecting structures, and where the connecting structures, as well as the interfaces between the strand carrying elements and the structures of connection are sufficiently rigid, the tangent equivalent module of rigidity in extension E _and of the bearing assembly is substantially equal to the product of the tangent modulus of rigidity in extension E _t of each supporting wire element by the surface density D of supporting wire elements.

Advantageously, the equivalent secant module of rigidity in extension E _eq of the carrier assembly is at least equal to 0.1 MPa.

The equivalent secant modulus of rigidity in extension E _eq of the carrier assembly is considered to be a relevant parameter with respect to the radial deformation, or radial deflection, of the pneumatic type device, when the latter is inflated and subjected to a radial load. It is defined for the value of the radial extension of the carrier assembly, diametrically opposite the contact area, reached when the pneumatic type device is inflated to a nominal pressure P and crushed under a nominal radial load Z As described above, this equivalent secant modulus of rigidity in extension can be determined, in a known manner, from the constitutive law in extension of the bearing assembly obtained by a static tensile test on test piece: this is the slope of the line passing by the origin of the reference mark and by the point considered of the constitutive law.

Below a value of equivalent secant modulus of rigidity in extension E _eq equal to 0.1 MPa, the carrier assembly becomes too flexible and the strand carrier elements may be subjected to excessive elongations liable to cause their rupture.

Also advantageously, the carrier assembly having a surface density D of wire carrier elements, defined as the ratio between the sum of the average sections Sp of the wire carrier elements and the arithmetic mean S _M of the surface S _E of the structure of radially exterior connection and of the surface If of the radially interior connection structure, the surface density D of the supporting wire elements is at most equal to 10%. The surface density D of supporting wire elements is defined for a carrier assembly at rest, that is to say not subject to mechanical stresses. Above 10%, the surface density D of the supporting wire elements becomes too high, which results in an excessive number of supporting wire elements, and consequently an excessive mass and material cost of the supporting structure.

Generally, the surface density D of wire carrier elements is constant both in the circumferential direction and in the axial direction, that is to say that the distribution of the carrier elements is uniform both circumferentially and axially . The advantage of a constant surface density is that it contributes to giving the strip of bearing an almost cylindrical geometry, with a so-called “daisy effect” reduced compared to other pneumatic type devices of the prior art.

However, the surface density D of filar carrier elements may be variable in the circumferential direction and / or in the axial direction, that is to say that the distribution of the carrier elements is not necessarily circumferentially uniform and / or axially. In this case, the surface density D of the bearing load elements taken into account is an average surface density.

Still advantageously, the surface density D of filar carrier elements is at least equal to 0.05%. Below 0.05%, the surface density D of the supporting wire elements becomes too low, which causes, in the supporting wire elements, high stresses likely to cause their rupture, as well as excessive point forces at the level of the interfaces with the connecting structures capable of causing the rupture of the bearing assembly.

The tangent modulus of rigidity in extension E _t of any strand bearing element is advantageously at most equal to 2000 MPa, this tangent module being defined for the value of elongation of the strand bearing element reached opposite to l contact area when the pneumatic type device is inflated to a nominal pressure P and crushed under a nominal radial load Z. In other words, the tangent modulus of rigidity in extension of any strand bearing element must be sufficiently small, c that is to say the flexible carrier element flexible enough, to give the carrier assembly flexibility making it possible to significantly dampen the transmission of rolling vibrations from the pneumatic type device to the wheel, and thus reduce the internal noise in the vehicle. The tangent modulus of rigidity in extension E _t of the filar load-bearing element is equal to K _t * Lo / So, I being the tangent rigidity in extension, L _o being the initial length at rest and So the initial section at rest of l wire element. The tangent modulus of rigidity in extension E _t is determined for a level of deformation DL / L ₀ of a wire support element positioned opposite the contact area, when the pneumatic type device is inflated to a nominal pressure P and crushed under a nominal radial load Z. The tangent rigidity in extension K _t is deduced from the traction curve "force (N) / elongation (mm)" of the filar load-bearing element.

The secant modulus of rigidity in extension E _s of any strand bearing element is also advantageously at least equal to 1 MPa, this secant module being defined for the value of elongation of the strand bearing element reached opposite to the contact area when the pneumatic type device is inflated to a nominal pressure P and crushed under a nominal radial load Z. Below 1 MPa, the supporting wire element being very flexible, the surface density D of supporting wire elements necessary to ensure the wearing of the applied radial load becomes very high, and therefore results in an excessive load-bearing mass. The secant modulus of rigidity in extension E _s of the filar load-bearing element is equal to K _s * L ₀ / S ₀ , K _s being the secant rigidity in extension, L _o being the initial length at rest and So the initial section at rest of the wire carrying element. This secant modulus of rigidity in extension E _s is determined for a level of deformation DL / Lo of a filar carrier element positioned opposite the contact area, when the pneumatic type device is inflated to a nominal pressure P and crushed under a nominal radial load Z. The secant stiffness in extension K _s is deduced from the traction curve "force (N) / elongation (mm)" of the filar load-bearing element.

According to advantageous variants of the materials constituting the strand carrying elements, any strand carrying element comprises a polymeric material such as an aliphatic polyamide, an aromatic polyamide, a polyester, an elastane or any combination of the preceding materials. The aforementioned materials have the advantage of guaranteeing a satisfactory compromise between the load carrying capacity of the carrier assembly and the endurance of the strand bearing elements, by virtue of an adapted pre-tension of said strand bearing elements.

Advantageously, any supporting wire element forms, in a circumferential plane and with a radial direction, an angle AXp at most equal to 5 °. In the case where the angle AXp is not zero, that is to say in the case of a load-bearing structure made up of non-radial wire support elements in a circumferential plane, the load-bearing structure makes a contribution to the circumferential rigidity of the pneumatic type device.

Advantageously, any strand bearing element forms, in a meridian plane and with a radial direction, an angle AYp at least equal to 5 ° and at most equal to 45 °. A supporting structure made up of supporting supporting elements, forming a non-zero angle AY _P , that is to say non-radial in a meridian plane, thus contributes to the axial, or transverse, rigidity of the pneumatic type device.

According to a first preferred embodiment, the radially outer connecting structure and the radially inner connecting structure of the carrier assembly are respectively constituted by a radially outer fabric and by a radially inner fabric.

Thus, the two respectively radially exterior and radially interior connection structures, acting as interfaces between the load-bearing elements and the structures of revolution, respectively radially exterior and radially interior, are two fabrics. By fabric is meant a structure obtained by weaving elementary threads which can be made up of various types of material.

It should be noted that the surface S _E of the radially outer fabric is not necessarily identical to the surface S of the radially inner face of the radially outer structure of revolution to which it is secured. In addition, the radially outer fabric is not necessarily continuous and may consist of juxtaposed fabric elements: in this case, the surface S _E of the radially outer fabric is the sum of the surfaces of the juxtaposed fabric elements. In practice, the surface S _E is at most equal to the surface S, that is to say that the radially exterior fabric does not necessarily entirely cover the radially interior face of the radially exterior structure of revolution.

Similarly, the surface Si of the radially inner fabric is at most equal to the surface S 'of the radially outer face of the radially inner revolution structure to which it is secured, that is to say that the fabric radially interior does not necessarily entirely cover the radially exterior face of the radially interior structure of revolution. As with radially outer fabric, the radially inner fabric is not necessarily continuous and may consist of juxtaposed fabric elements: in this case, the surface Si of radially inner fabric is the sum of the surfaces of the juxtaposed fabric elements.

This design with fabrics as connecting structures advantageously makes it possible to have a sandwich structure which can be produced independently and integrated in a single block during the manufacture of the pneumatic type device. The sandwich structure thus obtained can be joined to the respectively radially exterior and radially interior structures of revolution by vulcanization, bonding or any other method of respectively radially exterior and radially interior tissue bonding.

According to a first variant of the first preferred embodiment, the radially outer fabric is a woven fabric comprising interlacing of a first family of threads, mutually parallel, each thread of the first family of the fabric radially exterior forming, with a circumferential direction of the pneumatic type device, an angle AE at least equal to 10 ° and at most equal to 45 °, and of a second family of wires, mutually parallel, the respective wires of the two families of threads being symmetrical with respect to an equatorial plane of the pneumatic type device and the radially inner fabric is a woven fabric comprising interlaces of a first family of threads, mutually parallel, each thread of the first family of the radially inner fabric forming, with the circumferential direction of the pneumatic type device, an angle AI substantially equal to 45 °, and of a second family of wires, mutually parallel, the respective wires of the two families of wires being symmetrical with respect to an equatorial plane of the device pneumatic type.

In general, a woven fabric, during its manufacture, usually consists of interlacing of a first family of threads parallel to each other, called weft threads, and of a second family of threads parallel to each other, called warp threads, perpendicular to the weft threads. The mechanical characteristics of such a fabric such as its rigidity in extension and its tensile strength, depending on the direction of the weft or that of the warp, depend on the characteristics of the elementary threads, such as, for elementary threads in textile , the titer, expressed in tex or g / l000 m, the toughness, expressed in cN / tex, and the standard contraction, expressed in%, these elementary threads being distributed according to a given density, expressed in number of threads / dm. All these characteristics are a function of the material of the wires and of the design of these wires.

A woven fabric as previously described is, first, linked to the ends of the carrier elements as a constituent element of the sandwich structure. In the most general case, the sandwich structure thus comprises at least one screened fabric intended to be bonded, generally by bonding or vulcanization, either to the radially inner face of the radially outer structure of revolution, to become the radially outside screened fabric, either on the radially outer face of the radially inner revolution structure, to become the radially inner woven fabric.

Whether the screened fabric is intended to become the radially outside screened fabric or the radially inside screened fabric, it is placed on a cylindrical surface, so that the warp and weft threads, perpendicular to each other, form initially, with the circumferential direction XX 'of the pneumatic type device, an angle substantially equal to 45 °.

After assembly of the sandwich structure in the pneumatic type device, the pneumatic type device is shaped, that is to say the diameter of the structure radially outer revolution increases while the diameter of the radially inner revolution structure remains constant. If the screened fabric is radially outer, its radial distance from the axis of revolution of the pneumatic type device increases significantly during shaping, its circumferential length increases and the angle formed by the warp threads and the weft yarns, with the circumferential direction XX 'of the pneumatic type device, initially equal to 45 °, decreases and becomes at least equal to 10 ° and at most equal to 45 °, after conformation. If the screened fabric is radially internal, its radial distance relative to the axis of revolution of the pneumatic type device remains almost constant during the shaping, its circumferential length does not vary or little and the angle formed by the son of warp and weft threads, with the circumferential direction XX 'of the pneumatic type device, initially equal to 45 °, remains substantially equal to 45 °, after conformation.

According to a second variant of the first preferred embodiment, the radially outer fabric is a woven fabric comprising interlacing of a first family of threads, parallel to each other, each thread of the first family of the radially outer fabric forming, with a circumferential direction of the pneumatic type device, an angle AE at most equal to 5 °, and of a second family of wires, mutually parallel, the respective wires of the two families of wires forming between them an angle BE at least equal to 85 ° and at most 95 ° and the radially inner fabric is a woven fabric comprising interlaces of a first family of threads, mutually parallel, each thread of the first family of the radially inner fabric forming, with the circumferential direction of the device of pneumatic type, an angle AI at most equal to 5 °, and of a second family of wires, mutually parallel, the respective wires of the two families of sons between them an angle BE at least equal to 85 ° and at most 95 °. Such fabrics are conformable during inflation of the pneumatic type device, that is to say that the various angles described above, for the woven fabrics, remain substantially constant during the pressurization, which makes it possible to maintain an angulation. substantially constant of the bearing load-bearing elements.

In the case of a radially outer woven fabric, any strand carrying element advantageously comprises at least one radially outer end portion integrated into the radially outer woven fabric and formed by interlacing with respect to at least one wire of a of the two families of sons and parallel to the other family of sons In the case of a radially inner woven fabric, any strand carrying element also advantageously comprises at least one radially inner end portion integrated into the radially inner woven fabric and formed by interlacing with respect to at least one wire. one of the two families of sons and parallel to the other families of sons.

Preferably, the carrier assembly comprises two respectively radially exterior and radially interior woven fabrics and wire support elements constituted by wires, the end portions of which are integrated in each fabric respectively radially exterior and radially interior, parallel to the one of the families of fabric threads. Such a sandwich structure has the advantage of being able to be produced in a single weaving step. According to a particular variant, several wire carrying elements are constituted by a continuous wire passing alternately through each fabric respectively radially exterior and radially interior.

As regards the nature of the materials, the respectively radially exterior and radially interior fabrics comprise a polymeric material such as an aliphatic polyamide, an aromatic polyamide, a polyester, an elastane, or a metallic material, such as steel, or a glass or carbon material or any combination of the above materials. Polymers, in particular elastomers, and metal, such as steel, are commonly used in the tire industry. Glass and carbon are possible alternative materials for use in tires.

According to a second embodiment, the radially outer connecting structure and the radially inner connecting structure of the carrier assembly are respectively integrated in the radially outer revolution structure and in the radially outer revolution structure. This is the case, for example, for an anchoring of the ends of the supporting wire elements directly in the structures of revolution radially exterior and radially interior respectively. This second embodiment is a priori more complex to manufacture than the first preferred embodiment with fabrics as connecting structures.

Advantageously, the radially inner structure of revolution comprises, on a radially inner face, a connecting layer intended to be fixed to the mounting means on the vehicle. The bonding layer generally comprises at least one elastomeric material, but not necessarily of reinforcing reinforcement. Layer fixation connection on the mounting means can be achieved by gluing, by locking means on the wheel or, possibly, by the only hooping resulting from the inflation pressure forces of the pneumatic type device.

In order to manufacture the pneumatic type device previously described, a method is implemented comprising:

-a step of assembling a raw blank of the pneumatic type device during which is wound around an assembly support substantially of revolution around an axis of revolution, the carrier assembly as described above, according to the circumferential direction of the assembly support,

a step of molding the assembled green blank during which the radially outer connecting structure is moved radially apart from the radially inner connecting structure, and

- A step of heating the molded green blank so as to crosslink at least partially the molded green blank.

During the heating step of the molded green blank, the tension in each wire support element is zero in order to avoid any relaxation of the material or materials constituting the wire support elements.

The invention also relates to a mounted assembly comprising a pneumatic device according to one of the previously described embodiments, mounted on a mounting means on the vehicle.

The present invention will be better understood with the aid of FIGS. 1 to 6 presented below:

-Figure 1: perspective view in partial section of a pneumatic type device according to the invention.

-Figure 2A: view of a circumferential section of a pneumatic type device according to the invention, in the crushed state, with compression of the strand carrier elements in Making contact.

-Figure 2B: view of a circumferential section of a pneumatic type device according to the invention, in the crushed state, with tensioning of the strand carrier elements in Making contact.

-Figure 3A: view of a meridian section of a pneumatic type device according to the invention, in the crushed state, with compression of the strand carrier elements in the contact area.

-Figure 3B: perspective view of a load-bearing element.

-Figure 4A: view in meridian section of a sandwich structure comprising two woven fabrics and a supporting structure.

-Figure 4B: top view of a sandwich structure comprising two woven fabrics and a supporting structure.

-Figure 5: law of behavior-type of an assembly carrying a pneumatic type device according to the invention.

FIG. 6: evolution of the interior noise level as a function of the tangent equivalent module of rigidity in extension of an assembly carrying a pneumatic type device according to the invention.

Figure 1 shows a perspective view in partial section of a pneumatic type device 1 according to the invention, mounted on a mounting means 4 or rim, and comprising a radially outer structure of revolution 2 having a face radially interior 23 and two axial ends 24, a radially interior structure of revolution 3 having a radially exterior face 33 and two axial ends 34, an interior annular space 5, a support assembly 8 comprising a support structure 6 and two respectively radially connecting structures exterior 71 and radially interior 72, and two sides 9. The radially exterior structure of revolution 2 has an axis of revolution which is the axis of rotation YY ′ of the pneumatic type device and is intended to come into contact with a ground by l 'Intermediate of a tread 21 comprising at least one elastomeric material. In addition, the radially outer structure of revolution 2 comprises a circumferential reinforcing reinforcement 22, constituted, in the present case, by a single reinforcing layer. The radially inner revolution structure 3, coaxial with the radially outer revolution structure 2, is intended to ensure the connection of the pneumatic type device 1 with the mounting means 4. The radially inner revolution structure 3 comprises at least one polymeric material , most often an elastomeric blend. The interior annular space 5 is radially delimited by the respectively radially exterior 2 and radially interior 3 revolution structures. The load-bearing structure 6 constituted by a plurality of identical thread supporting elements 61, not interconnected in the interior annular space 5 and extending continuously from a radially outer connecting structure 71, integral with the radially inner face 23 of the radially outer revolution structure 2, up to a radially connecting structure interior 72, secured to the radially exterior face 33 of the radially interior structure of revolution 3, at least a portion of the load-bearing elements 61, connected to the portion of the radially exterior structure of revolution 2 not in contact with the ground, are in tension . The two radially outer 71 and radially inner 72 connecting structures of the carrier assembly 8 are linked, and most often bonded, respectively to the radially inner face 23 of the radially outer revolution structure 2 and to the radially outer face 33 of the radially inner revolution structure 3. In addition, the pneumatic type device 1 comprises two sidewalls 9, connecting the axial ends (24, 34) of the respectively radially outer 2 and radially inner 3 revolution structures and axially delimiting the annular space interior 5, so that the interior annular space 5 constitutes a closed cavity which can be pressurized by an inflation gas. Finally, the pneumatic type device 1 comprises a carcass reinforcement (10, 11) extending radially in each sidewall 9 and axially at least partly in the radially outer structure of revolution 2 and at least partly in the structure of revolution radially inner 3. The carcass reinforcement (10, 11) is constituted by two carcass reinforcement portions each extending radially in a sidewall 9, from a first end positioned in the radially outer revolution structure 2 up to a second end positioned in the radially inner structure of revolution 3. In the present case, the respective first ends and the respective second ends of the two carcass reinforcement portions are disjoint.

2A shows a circumferential section of a pneumatic type device 1 according to the invention, mounted on a mounting means 4, in its inflated and crushed state, that is to say subjected to a radial load nominal Z, with compression of the supporting wire elements 61 in the contact area. The carrying structure 6 is constituted by a plurality of supporting wire elements 61, not interconnected in the interior annular space 5 and connecting the radially outer revolution structure 2 to the radially interior revolution structure 3. The pneumatic type device 1, subjected to a nominal radial load Z, is in contact with a flat ground by a contact surface A, having a circumferential length X _A.

Figure 2B shows a circumferential section of a pneumatic type device 1 according to the invention, mounted on a mounting means 4, in its inflated and crushed state, that is to say subjected to a radial load nominal Z, with extension of load-bearing elements wires 61 in the contact area. In this case, the supporting wire elements 61 remain in extension and are not subjected to buckling, because of the pre-tension which was generally applied to them during the manufacture of the pneumatic type device, of its mounting on a means mounting and / or inflation.

3A shows a meridian section of a pneumatic type device 1 according to the invention, mounted on a mounting means 4. As described for Figure 1, the pneumatic type device 1 comprises a structure of revolution radially outer 2 having a radially inner face 23 and two axial ends 24 and comprising a tread 21 and a reinforcement 22, a radially inner revolution structure 3 having a radially outer face 33 and two axial ends 34, an inner annular space 5 of height H, a support assembly 8 comprising a support structure 6 with wire support elements 61 and two respectively radially external connection structures 71, having a surface S _E , and radially interior 72, having a connection surface Si _, two sides 9 and a carcass reinforcement (10, 11). The pneumatic type device 1, subjected to a nominal radial load Z, is in contact with a flat ground by a contact surface A. As seen previously, in the case of FIG. 2A, the supporting wire elements 61, positioned at the 'opposite to the contact area are under tension, while the load-bearing elements 61, connected to the portion of radially outer structure of revolution 2 in contact with the ground, are subjected to buckling in compression.

FIG. 3B shows a wire or one-dimensional support element 61 having a circular average section Sp, and a length L _P. The mean section Sp is defined by a smaller characteristic dimension E and a larger characteristic dimension L both equal, in the example presented, to the diameter of the circle, and characterized by its form ratio K equal to L / E, therefore equal to 1 in this case. In addition, the smallest characteristic dimension E of the average section Sp of the carrier element 61, that is to say in its present case, its diameter, is at most equal to 0.02 times the average radial height H of l interior annular space 5.

FIG. 4A is a view in meridian section of a support assembly 8 comprising two connection structures (71, 72) of the woven fabric type and a support structure 6. The two woven fabrics (71, 72) are intended for becoming the radially outer and radially inner fabrics respectively, after integration into the pneumatic type device. Each screened fabric (71, 72) is formed by perpendicular intertwining of a first family of threads (711, 721), called weft threads, and of a second family of threads (712, 722), called warp threads. In addition, the wired supporting elements 61 of the carrying structure 6 are constituted by continuous wires connecting the two screened fabrics (71, 72) and comprising portions (611, 612) intersecting with the respective weft son (711, 721) of said woven fabrics (71, 72), parallel to the warp threads (712, 722) and constituting the ends of the carrying elements 61 integrated in each fabric. The advantage of such a design is that it can weave the sandwich structure in one step.

4B shows a top view of a support assembly 8 comprising two connecting structures (71, 72) of woven fabric type and a support structure 6. The woven fabric 71 shown is formed by perpendicular intersections of the first family of sons 711, called weft threads, and of the second family of threads 712, called warp threads. In addition, FIG. 4B shows portions of threads 611, intersected with the weft threads 711, parallel to the warp threads 712 and constituting ends of the carrying elements 61 integrated in the screened fabric 71.

FIG. 5 is a typical behavior law of a support assembly, constituted by the support structure and the two connecting structures, respectively radially exterior and radially interior, which is a sandwich structure comparable to an equivalent composite material. This equivalent composite material can be characterized mechanically by a constitutive law representing the evolution of the stress in extension L / S, applied to the composite material in a direction normal to the connection structures, according to its deformation in extension or relative elongation DL / L. This behavior law can typically be determined by a static tensile test on a test piece constituted by a sample of the sandwich structure, comprising the load-bearing structure connected to the two connecting structures. At any point of the constitutive law thus obtained, the equivalent tangent modulus of rigidity in extension E _and is defined by the slope of the line tangent to the constitutive law at the point considered and the equivalent secant modulus of rigidity in extension E _es is defined by the slope of the line passing through the origin of the reference frame and by the point considered of the law of behavior. The inventors have chosen to determine, for the bearing assembly, an equivalent tangent modulus of rigidity in extension E _and and an equivalent secant modulus of rigidity in extension E _es , for the value of radial extension of the bearing assembly, diametrically to opposite of the contact area, reached when the pneumatic type device is inflated to a nominal pressure P and crushed under a nominal radial load Z. It should be noted that every single supporting element, taken individually, has a law of behavior of this type.

FIG. 6 is a graph representing the evolution of the interior noise level B, expressed in base 100 with respect to a maximum noise level defined as equal to 100, as a function of the equivalent tangent modulus of rigidity in extension E _and of the carrier assembly of a pneumatic type device, expressed in MPa. This curve is a theoretical curve, resulting from a numerical simulation. The noise level B is an increasing nonlinear function of the equivalent tangent modulus of rigidity in extension E _and of the assembly, with a strong growth below 1 MPa, a weakest growth between 1 MPa and 2 MPa, to reach an almost constant maximum level above 2 MPa. Consequently, the inventors fixed at 1 MPa the threshold of equivalent tangent modulus of rigidity in extension E _and , below which the noise level is considered acceptable, typically less than 95, the maximum noise level being defined by convention as equal. 100.

The pneumatic type device for a passenger vehicle according to the invention, having the noise performance characteristics shown in FIG. 6, corresponds to a tire of dimension 255/35 R19 XL having a load index equal to 96, inflated at a nominal pressure P equal to 2.5 bars and subjected to a nominal radial load Z equal to 557 daN. The load-bearing assembly of this pneumatic-type device is constituted by a load-bearing structure, constituted by identical thread-carrying elements made of elastane, and two connecting structures, respectively radially exterior and radially interior, constituted by woven polyester fabrics of polyethylene terephthalate type. (FART). The supporting wire elements form, in a circumferential plane and with a radial direction, a zero angle AXp, that is to say are radial in a circumferential plane. The supporting wire elements are elastane yarns, made up of a filament yarn having a titer equal to 187 tex (g / l000m). Such an elastane wire has, at the nominal operating point of the pneumatic type device, resulting from the application of the nominal pressure and load conditions described above, a tangent modulus of rigidity in extension E _t and a secant module of rigidity in extension E _s substantially equal to each other and equal to 0.24 MPa, corresponding respectively to a tangent rigidity in extension K ' _t and a secant rigidity in extension K' _s substantially equal to each other and equal to 0.55 cN / tex, these two rigidities in extension being deduced from a traction curve "force (N) / relative elongation (%)" of the wire having a substantially linear evolution up to the operating point considered. In in addition to the supporting wire elements are distributed with a density equal to 216,000 reinforcements / m ² , corresponding to a surface density equal to 3.4%. Indeed, in the present example, knowing that, on the one hand, the strand carrying elements have a titer equal to 187 tex or 187 g / km (or 187c10 ⁶ g / mm), and that, on the other hand, the density of the elastane is approximately 1 2 × 10 ³ g / mm ³ , it is possible to calculate the area of a section of a filar carrier element

So = (187c10 ⁶ ) / (l.2xl0 ³ ) = 0.156 mm ² . Assuming a density of stranded supporting elements equal to 216,000 reinforcements / m ² , the total cross-sectional area of the stranded supporting elements is equal to 216,000 x 0.156 = 33,696 mm ² , for 1 m ² of connecting structure. The surface density is therefore equal to 33696 / 1.10 ⁶ = 0.034, that is to say a surface density of 3.4%. The woven fabrics respectively radially outside and radially inside comprise interlacing of a first family of threads, parallel to each other and forming, with a circumferential direction of the pneumatic type device, an angle A _E equal to 0 °, and a second family of wires, parallel to each other, the respective wires of the two families of wires forming between them an angle B equal to 90 °. The PET yarns of the first family forming an angle A _E equal to 0 °, called warp yarns, consist of a filament yarn having a count equal to 110 tex. The second family PET yarns forming an angle B _E with the first family equal to 90 °, called weft yarns, consist of a filament yarn having a count equal to 170 tex. In the preceding hypotheses described, the equivalent tangent modulus of rigidity in extension E _and of the bearing assembly, at the nominal operating point, is equal to 0.24 MPa, therefore less than 1 MPa. It should be noted that the equivalent secant modulus of rigidity in extension E _es of the bearing assembly, at the nominal operating point, is also substantially equal to 0.24 MPa, due to the substantially linear behavior of the equivalent material of the bearing assembly up to 'at the operating point considered.

Claims

1. Pneumatic type device (1), intended to equip a vehicle, comprising:

-a radially outer structure of revolution (2) whose axis of revolution is the axis of rotation (YY ') of the pneumatic type device and intended to come into contact with a ground via a tread (21) comprising at least one elastomeric material, the radially outer revolution structure (2) having two axial ends (24) and a radially inner face (23), and the radially outer revolution structure (2) comprising a circumferential reinforcement of reinforcement (22),

a radially inner structure of revolution (3), coaxial with the radially outer structure of revolution (2) and intended to ensure the connection of the pneumatic type device with a mounting means (4) on the vehicle, the structure of revolution radially inner (3) having two axial ends (34) and a radially outer face (33), and the radially inner structure of revolution (3) comprising at least one polymeric material,

an inner annular space (5) radially delimited by the radially inner face (23) of the radially outer revolution structure (2) and by the radially outer face (33) of the radially inner revolution structure (3), -two sidewalls (9), connecting two by two the axial ends (24, 34) of the respectively radially exterior (2) and radially interior (3) structures of revolution and axially delimiting the interior annular space (5),

a carcass reinforcement (10, 11) extending radially in each sidewall (9) and axially at least partly in the radially outer structure of revolution (2) and at least partially in the radially interior structure of revolution (3 ),

-a supporting structure (6) constituted by a plurality of identical supporting wire elements (61), each having a medium section Sp, not interconnected in the interior annular space (5) and extending continuously from a radially outer connecting structure (71), having a surface S _E and secured to the radially inner face (23) of the radially outer revolution structure (2), up to a radially inner connecting structure (72), having a surface Si and secured to the radially outer face (33) of the radially inner revolution structure (3), so that, when the device pneumatic type is inflated to a nominal pressure P and crushed under a nominal radial load Z on a ground, at least part of the load-bearing elements (61), connected to the portion of the radially outer structure of revolution (2) not in contact with the ground, are in tension,

the supporting structure (6), the radially outer connecting structure (71) and the radially inner connecting structure (72) constituting a carrying assembly (8),

the bearing assembly (8) having an equivalent tangent modulus of rigidity in extension E _and and an equivalent secant module of rigidity in extension E _es , respectively defined for the value of radial extension of the bearing assembly (8), diametrically opposite the contact area, reached when the pneumatic type device (1) is inflated to a nominal pressure P and crushed under a nominal radial load Z,

characterized in that the equivalent tangent modulus of rigidity in extension E _and of the carrier assembly (8) is at most equal to 1 MPa.

2. A pneumatic type device (1) according to claim 1, in which the equivalent secant modulus of rigidity in extension E _eq of the carrier assembly (8) is at least equal to 0.1 MPa.

3. Pneumatic type device (1) according to one of claims 1 or 2,

the carrier assembly (8) having a surface density D of wire carrier elements (61), defined as the ratio between the sum of the average sections Sp of the wire carrier elements (61) and the arithmetic mean S _M of the surface S _E of the radially outer connecting structure (71) and of the surface Si of the radially inner connecting structure (72), in which the surface density D of filar support elements (61) is at most equal to 10%.

4. A pneumatic type device (1) according to any one of claims 1 to 3, the support assembly (8) having a surface density D of wire support elements (61), defined as the ratio between the sum of the sections means Sp of the supporting wire elements (61) and the arithmetic mean S _M of the surface S _E of the radially outer connecting structure (71) and of the surface Si of the radially inside connecting structure (72), in which the density surface area D of wire bearing elements (61) is at least equal to 0.05%.

5. A pneumatic type device (1) according to any one of claims 1 to

4, any wire supporting element (61) having a tangent modulus of rigidity in extension E _t , defined for the elongation value of the wire supporting element (61) reached when the pneumatic type device (1) is inflated to a nominal pressure P and crushed under a nominal radial load Z, in which the tangent modulus of rigidity in extension E _t of any supporting wire element (61) is at most equal to 2000 MPa.

6. A pneumatic type device (1) according to any one of claims 1 to

5, any wire supporting element (61) having a secant modulus of rigidity in extension E _s , defined for the elongation value of the wire supporting element (61) reached when the pneumatic type device (1) is inflated to a nominal pressure P and crushed under a nominal radial load Z, in which the secant modulus of rigidity in extension E _s of any wire supporting element (61) is at least equal to 1 MPa.

7. A pneumatic type device (1) according to any one of claims 1 to

6, in which any strand carrying element (61) comprises a polymeric material such as an aliphatic polyamide, an aromatic polyamide, a polyester, an elastane or any combination of the preceding materials.

8. A pneumatic type device (1) according to any one of claims 1 to

7, in which any supporting wire element (61) forms, in a circumferential plane (XZ) and with a radial direction (ZZ '), an angle AX _P at most equal to 5 °.

9. A pneumatic type device (1) according to any one of claims 1 to

8, in which any supporting wire element (61) forms, in a meridian plane (YZ) and with a radial direction (ZZ '), an angle AY _P at least equal to 5 ° and at most equal to 45 °.

10. Pneumatic type device (1) according to any one of claims 1 to

9, in which the radially outer connecting structure (71) and the radially inner connecting structure (72) of the carrier assembly (8) are constituted respectively by a radially outer fabric (71) and by a radially inner fabric (72 ).

11. A pneumatic type device (1) according to claim 10, in which the radially outer fabric (71) is a woven fabric comprising interlacing of a first family of wires (711), mutually parallel, each wire of the first family (711) of the radially outer fabric (71) forming, with a circumferential direction (XX ′) of the pneumatic type device, an angle A _E at least equal to 10 ° and at most equal to 45 °, and a second family of threads (712), mutually parallel, the respective threads of the two families of threads (711, 712) being symmetrical with respect to an equatorial plane (XZ) of the pneumatic type device and in which the radially inner fabric (72) is a woven fabric comprising interlaces of a first family of threads (721), parallel to each other, each thread of the first family (721) of the radially inner fabric (72) forming, with the circumferential direction (XX ') of the device of pneumatic type, an angle Ai substantially equal to 45 °, and of a second family of wires (722), mutually parallel, the respective wires of the two families of wires (721, 722) being symmetrical with respect to an equatorial plane (XZ) of the pneumati type device than.

12. A pneumatic type device (1) according to claim 10, in which the radially outer fabric (71) is a woven fabric comprising interlacing of a first family of wires (711), mutually parallel, each wire of the first family (711) of the radially outer fabric (71) forming, with a circumferential direction (XX ′) of the pneumatic type device, an angle A _E at most equal to 5 °, and of a second family of threads (712), parallel to each other, the respective threads of the two families of threads (711, 712) forming between them an angle B _E at least equal to 85 ° and at most 95 ° and in which the radially inner fabric (72) is a woven fabric comprising interleaves of a first family of wires (721), mutually parallel, each wire of the first family (721) of the radially inner fabric (72) forming, with the circumferential direction (XX ′) of the pneumatic type device, an angle Ai at most equal to 5 °, and d the second family of wires (722), mutually parallel, the respective wires of the two families of wires (721, 722) between them an angle B _E at least equal to 85 ° and at most 95 °.

13. A pneumatic type device (1) according to one of claims 11 or 12, in which any wire support element (61) comprises at least one radially outer end portion (611) integrated into the radially outer woven fabric (71) and formed by intertwining with respect to at least one wire from one of the two families of wires (711, 712) and parallel to the other family of wires (711, 712).

14. A pneumatic type device (1) according to any one of claims 11 to 13, in which any strand carrying element (61) comprises at least one portion radially inner end (612) integrated into the radially inner woven fabric (72) and constituted by intertwining with respect to at least one thread from one of the two families of threads (721, 722) and parallel to the other families of son (721, 722).

15. Mounted assembly (1, 4) comprising a pneumatic type device (1) according to any one of the preceding claims mounted on a mounting means (4) on the vehicle.