Tire optimized for rolling resistance and road handling

Abstract

The present invention relates to a tire (1) for a motor vehicle comprising in a meridian plane: two beads (50) intended to be mounted on a rim, two sidewall layers (30) connected to the beads (50), a crown (20) comprising a tread (10), said crown (20) having a first side connected to the radially outer end of one of the two sidewall layers (30) and having a second side connected to the radially outer end of the other of the two sidewall layers (30); at least one carcass reinforcement (90) extending from the two beads (50) to the crown (20), the carcass reinforcement (90) being anchored in the two beads (50) to a bead (53); The tire (1) comprises a composite material consisting of an elastomeric blend including threads sewn into the elastomeric blend to form reinforcements oriented along the stitching directions. Figure 2-A

Description

Title of the invention: Tire optimized for rolling resistance and road handling Scope of the invention

[0001] The present invention relates to a tire whose bead is optimized to achieve an advantageous performance compromise in rolling resistance and road handling compared to conventional designs. Although not limited to this type of application, the invention is described more particularly with reference to a radial tire intended for mounting on passenger cars or light trucks. Definitions

[0002] By convention, we consider a frame (O, OX, OY, OZ), whose center O coincides with the geometric center of the tire, the circumferential direction OX, axial direction OY, and radial direction OZ respectively designate a direction tangent to the rolling surface of the tire in the direction of rotation, a direction parallel to the axis of rotation of the tire, and a direction orthogonal to the axis of rotation of the tire.

[0003] By radially inside, respectively radially outside, we mean closer, respectively further from the axis of rotation of the tire.

[0004] By axially inside, respectively axially outside, we mean closer, respectively further from the equatorial plane of the tire, the equatorial plane of the tire being the plane passing through the middle of the tread of the tire and perpendicular to the axis of rotation of the tire.

[0005] The construction of the tire is usually described by a representation of its constituents in a meridian plane, that is to say, a plane containing the axis of rotation of the tire. Such a choice is motivated, as a first approximation, by the axisymmetry of the geometry of the tire around its axis of rotation.

[0006] A tire includes a crown, intended to come into contact with a ground by means of a tread, the two axial ends of which are connected by means of two sidewalls to two beads ensuring the mechanical connection between the tire and the rim on which it is intended to be mounted.

[0007] A radial tire further comprises a reinforcing reinforcement, consisting of a crown reinforcement, radially inside the tread, and a carcass reinforcement, radially inside the crown reinforcement.

[0008] The crown reinforcement of a radial tire comprises a superposition of crown layers extending circumferentially, radially outside the carcass reinforcement. Each crown layer is made up of reinforcements parallel to each other and coated with a polymeric material of the elastomer type or elastomeric mixture. The assembly consisting of the crown reinforcement and the tread is called the crown.

[0009] The carcass reinforcement of a radial tire relevant to the invention typically comprises at least one carcass layer made of metallic or textile reinforcing elements, each coated in an elastomeric coating compound. This at least one carcass layer includes a main portion connecting the two beads and winding, within each bead, around an annular reinforcing structure, which is most often a bead. Generally, each bead includes a padding layer positioned axially external to the bead and axially internal to a sidewall.

[0010] An elastomeric mixture is understood to be an elastomeric material obtained by mixing its various constituents. An elastomeric mixture classically comprises an elastomeric matrix with at least one diene elastomer of the natural or synthetic rubber type, at least one reinforcing filler of the carbon black and / or silica type, a crosslinking system most often based on sulfur, and protective agents.

[0011] The expression "based on" composition means a composition comprising the mixture and / or reaction product of the different constituents used, some of these basic constituents being capable of, or intended to, react with each other, at least in part, during the different phases of manufacturing the composition, in particular during its crosslinking or vulcanization.

[0012] The expression "part by weight per hundred parts by weight of elastomer" (or pce) is to be understood in the context of the present invention as the part, by mass per hundred parts of elastomer present in the rubber composition considered.

[0013] An elastomeric blend can be mechanically characterized, particularly after curing, by its dynamic properties, such as a dynamic shear modulus G* = (G'² + G”²)l / ², where G' is the elastic shear stiffness modulus and G” is the viscous shear modulus, and a dynamic loss Tanô = G” / G'. The dynamic shear modulus G* and the dynamic loss Tanô are measured on a Metravib VA4000 viscoanalyzer, according to ASTM D 5992-96. The response of a vulcanized elastomeric blend sample in the form of a sinusoidal alternating simple shear load, at a frequency of 10 Hz, at a temperature of 23 °C, is recorded. A strain amplitude sweep is performed from 0.1% to 50% (forward cycle), then from 50% to 0.1%. (return cycle). For the forward cycle, the maximum observed value of Tan(ô) is indicated, denoted Tan(ô)max. For this same forward cycle, the value of the dynamic elastic shear modulus, G*, is also indicated.

[0014] An elastomeric compound can also be characterized by static mechanical properties. Tensile tests allow the determination of elastic stresses and breaking properties. Unless otherwise specified, they are carried out in accordance with French standard NFT 46-002 of September 1988. The so-called "nominal" secant moduli (or apparent stresses, in MPa) are measured at 10% elongation (denoted "MA10") and 100% elongation ("MA100") at the second elongation (i.e., after one accommodation cycle). All these tensile measurements are carried out under normal temperature (23±2°C) and humidity (50±5% relative humidity) conditions, according to French standard NF T 40-101 (December 1979). The breaking stresses (in MPa) and elongations at break (in %) are also measured at a temperature of 23°C. Previous technique

[0015] A person skilled in the art, a tire designer, knows that the expected functions of a tire are at least threefold. First, it must carry the load resulting from the vehicle's mass and all the additional loads related to the vehicle's dynamic movements, as well as any aerodynamic loads at high speed. Second, it must be able to guide the vehicle along the trajectories chosen by the driver, and finally, it must transmit to the road the acceleration or braking forces chosen by the driver.

[0016] The crown reinforcement is an essential element that contributes decisively to the three functions of supporting, guiding, and transmitting. In a typical design, said crown reinforcement, with at least two cross-laminated metal layers, encircles the carcass reinforcement to provide the tire with the necessary strength to perform its supporting function.

[0017] The Guidance function is also known as "road behavior." This refers to the responses of a vehicle / tire assembly to various driver inputs (steering, acceleration, braking, etc.). This behavior is essential both for safety, ensuring vehicle stability, and for driving pleasure.

[0018] The tire plays a key role in road behavior because it ensures, at the end of the chain, the transmission of forces between the vehicle and the ground in order to maintain the trajectory defined by the driver.

[0019] When cornering, to keep the vehicle on its trajectory, a force equivalent to (but in the opposite direction to) the centrifugal force that tends to eject the vehicle from its trajectory must be generated. This lateral force must be generated by the vehicle's four tires to overcome the centrifugal force.

[0020] The deformation of the tread blocks in contact with the ground generates a lateral force. The mechanism that allows the tire to deform the tread blocks when cornering is called drift. Drift is the angle between the direction of the wheel and the trajectory followed by the vehicle. When cornering, this angle is not zero in order to allow the tire to deform the tread blocks and thus generate the necessary lateral forces.

[0021] Transverse drift stiffness is defined as the variation of the transverse forces generated in the contact area of ​​the moving tire compressed by the load, as a function of the drift angle applied to the tire. Transverse drift stiffness is expressed in Newtons per degree (N / °).

[0022] For small drift angles, i.e., angles less than 4°, the transverse force, parallel to the axis of rotation of the tire, is proportional to the drift angle. The transverse drift stiffness is equal to this proportionality coefficient.

[0023] Transverse drift stiffness is an essential mechanical quantity that links the tire to the vehicle and determines the quality of the vehicle's behavior on the road.

[0024] Rolling resistance is another performance characteristic addressed in the invention. Rolling resistance is one of the forces that oppose the forward motion of the vehicle. The rolling resistance coefficient (RRC) of a tire is the rolling resistance force expressed per unit load on the tire. The coefficient is expressed in kg / t.

[0025] Rolling resistance is essentially linked to tire deformation. For example, the sidewall beads account for 20% to 30% of the tire's rolling resistance, while the tread contributes 60% to 80%.

[0026] Reducing greenhouse gas emissions from transportation is one of the major challenges facing vehicle manufacturers today. Tires represent a significant source of progress through a reduction in rolling resistance, as this has a direct impact on vehicle fuel consumption. For example, a 20% reduction in the rolling resistance of a passenger car tire can save approximately 3% of fuel per 100 km in the combined cycle.

[0027] The choice of bead architecture plays a crucial role in establishing a compromise between road handling and rolling resistance. Among the tire design parameters, those skilled in the art are familiar with the impact of the tread layers on the desired performance compromise. In each bead, the tread layer is chosen so that its stiffness modulus The dynamic elastic modulus along the transverse direction (tire axis, OY direction) must be greater than 10 MPa. In this way, the tread layers contribute to the tire's drift stiffness. However, in general, this high level of the shear modulus of a tread layer is also accompanied by a high level of hysteresis, and therefore degrades the tire's rolling resistance. It is known that for a passenger car tire, the tread layer accounts for approximately 10% of the tire's rolling resistance.

[0028] It is known to those skilled in the art that various techniques exist, based either on the geometry of the tread layer or on its mechanical properties, to arrive at a suitable choice regarding the compromise between rolling resistance and road handling. In documents FR2983123, FR2971733, FR2970902, and FR2968601, a compromise is sought by reducing the shear modulus of the tread layer while increasing its volume to compensate for the lack of rigidity. This results in a significant increase in the tire's mass and therefore its production cost, making this type of approach prohibitively expensive.

[0029] Other approaches have been initiated by increasing the rigidity of the stuffing layer by adding synthetic or organic fibers, as taught in documents EP3057810, or JP2013079050, but again without achieving conclusive results.

[0030] Finally, in documents EP2655098 and EP185871, a layer of composite material was introduced into the bead. This layer comprises metallic or fabric reinforcements coated with an elastomeric compound and positioned within the bead. However, this intrusive approach to bead manufacturing excessively increases the industrial cost of the tire.

[0031] The inventors have set themselves the objective of establishing an advantageous compromise of performance in rolling resistance and road behavior which solves the difficulties listed above. Description of the invention

[0032] This objective has been achieved by a motor vehicle tire comprising, in a meridian plane: two beads intended to be mounted on a rim, two sidewall layers connected to the beads, a crown comprising a tread, said crown having a first side connected to the radially outer end of one of the two sidewall layers and having a second side connected to the radially outer end of the other of the two sidewall layers; at least one carcass reinforcement extending from the two beads to the crown, the carcass reinforcement comprising a plurality of carcass reinforcement elements and being anchored in the two beads to a bead, characterized in that said tire comprises at less a composite material consisting of an elastomeric mixture comprising threads sewn into said elastomeric mixture to form reinforcements oriented along stitching directions.

[0033] The principle of the invention is to replace initial elastomeric compound profiles obtained after an extrusion phase with composite materials resulting from stitching textile threads into said elastomeric compound profiles. In this way, a portion of the compound volumes of the initial profiles are replaced by stitching threads that are less hysteretic. Furthermore, the composite material profiles are stiffer than the initial compound profiles, i.e., their dynamic elastic shear moduli are significantly higher. It follows that a tire of the invention incorporating such composite profiles deforms less than a prior art tire, and therefore the rolling resistance of said tire of the invention is lower.

[0034] In particular, composite material profiles can be used in the bead sections, providing the required level of transverse shear stiffness (in the OY axis direction of the tire) to improve lateral drift stiffness and thus the vehicle's handling. Furthermore, with less deformation, rolling resistance is reduced.

[0035] According to the inventors, there are two main methods for obtaining composite fabrics used in pneumatic design. One method involves fabrics produced by the direct calendering of a network of parallel and equidistant reinforcements, which consists of applying a layer of elastomeric blend on either side of the network of parallel reinforcements to obtain a composite layer. This is the so-called "straight grain" method.

[0036] Another approach involves connecting the reinforcements with a weft yarn, often orthogonally to the direction of said reinforcements, so that the parallel reinforcements and the weft yarns form a woven fabric. A calendering step is then carried out on both sides of the woven fabric to produce a composite layer.

[0037] The use of woven fabrics in the design of passenger car, aircraft, and agricultural tires is well known. Weft yarns were initially introduced to improve the productivity of fabric manufacturing compared to straight grain processes.

[0038] The invention proposes a new approach where the reinforcements are sewn directly into the elastomeric mixture thus avoiding the calendering step, but introduces a sewing step downstream of the extrusion phase.

[0039] The detailed sewing step in [Fig.4] has a limited impact on the process, thus avoiding too much degradation in the cost price of the tire.

[0040] The main characteristic of the invention leads to the tire of the invention characterized in that it achieves a compromise of performance in road handling and in rolling resistance thanks to the use of composite profiles providing additional transverse shear stiffness.

[0041] Other features related to different embodiments of the invention contribute to further improving the performance compromise of the tire. Most often, these features relate to properties of the stitching such as direction and stitching thread density.

[0042] Advantageously, the composite material is sewn with a seam such that the distance between two consecutive stitch points is between 1 mm and 50 mm.

[0043] The distance between two stitching points is illustrated in Figures 3-A and 3-C. Textile threads provide rigidity to the composite profile. Thus, the smaller the distance between two stitching points, the more rigid the composite profile. According to the inventors, when the distance is less than or equal to 1 mm, the difficulty in obtaining a high-quality composite profile leads to numerous rejections. When the distance is greater than 50 mm, the gain in rigidity may be reduced.

[0044] According to a first preferred embodiment, the composite material is stitched with a seam such that the distance between two consecutive stitches is constant; alternatively, according to a second embodiment, the composite material is stitched with a seam such that the distance between two consecutive stitches is variable. This latter alternative is encountered when manufacturing composite profiles with complex geometries.

[0045] Advantageously, the composite material is stitched with a seam such that the distance between two consecutive stitch lines is variable, a stitch line being a succession of stitches in a given direction. As seen in the previous example, this embodiment is particularly suitable for profiles with complex geometries. Alternatively, another option is possible: the composite material is stitched with a seam such that the distance between two consecutive stitch lines is constant, a stitch line being a succession of stitches in a given direction.

[0046] Advantageously, the thread density of a stitched composite material being the number of stitch lines per decimeter, measured in the orthogonal direction of said stitching threads of said composite material, said tire is characterized in that the composite material has a thread density between 15 threads per decimeter and 150 threads per decimeter.

[0047] Yarn density is another parameter that controls the stiffness level of the stitched composite material. The higher the yarn density, the stiffer the composite material.

[0048] Other features of the invention related to the nature and assembly of the sewing thread contribute to further improving the desired performance compromise.

[0049] Advantageously, the sewing threads are textile cables, each cable being obtained by twisting N strands of a textile material with a twist T2 in a given direction DI (respectively direction S or Z), with N>1, each strand resulting from overtwisting a twist T1 of a yarn of said textile material, in an opposite direction D2 (respectively Z or S).

[0050] The raw material used in the manufacture of a textile cable is yarn stored by winding onto spools weighing 4 to 12 kg. It is a flat strand composed of continuous elementary filaments, identical in both appearance and mechanical properties; this strand comes directly from the spinning mills. A yarn is generally defined by the nature of the material that constitutes the filaments (polyethylene terephthalate, aliphatic polyamide (Nylon), Rayon, aromatic polyamide (Aramid)); its linear density, expressed in tex, which represents the mass in grams of 1000 meters of yarn; the number of elementary filaments constituting the yarn (200 to 1500); and the degree of interlacing of the elementary filaments.

[0051] From the yarns, double-twisted textile cables (T1, T2) are produced, which are prepared by a process called twisting, in which: • during a first step, overtwisting, each yarn or multifilament fiber (in English "yarn") constituting the final cable is first individually twisted on itself (according to an initial twist Tl) in a given direction DI (respectively direction S or Z), to form a strand in which the elementary filaments are subjected to a helical deformation around the fiber axis (or strand axis); • then, during a second stage, the twisting, several strands, generally two, three or four, of identical or different natures in the case of so-called hybrid or composite cables, are then twisted together according to a final twist T2 (which may be equal to or different from T1) in opposite direction D2 (respectively direction Z or S, according to a recognized nomenclature designating the orientation of the turns according to the crossbar of an S or a Z), to obtain the cable (in English "cord") or final assembly with several strands.

[0052] The role of twisting is to adapt the material properties in order to create transverse cohesion of the cable, improve resistance to compressive stresses, and distribute stresses across all filaments. This step in the twisting process is accompanied by a decrease in breaking strength and longitudinal modulus, and an increase in fatigue resistance with increased torsion. Ultimately, the process is parameterized to achieve a compromise between fatigue resistance and breaking strength.

[0053] The cable production process continues with a gluing phase to ensure bonding between the cable and the surrounding elastomeric compound. The quality of the textile / compound interface influences the fatigue performance of the glued cable.

[0054] Advantageously, the number N of strands in a textile cable is between 1 and 6, and preferably N = 2. An example of such a cable is the A-140 / 2 250 / 300, meaning that the cable is composed of two aramid strands, each with a count of 140 tex. The twist of the yarns during the overtwisting phase is 250 turns per meter, and that of the strands during the backtwisting phase is 300 turns per meter.

[0055] When N = 1, the cable comprises a single strand.

[0056] When N=2, an industrial direct cabling process allows for overtwisting and retwisting in a single manufacturing step, resulting in a significant productivity gain. However, when N=3, overtwisting and retwisting are performed in two separate operations to produce 3-strand constructions.

[0057] Preferably, the filament strands are made up of a homogeneous assembly of filaments of a textile material. Alternatively, filament strands can also be made up of a hybrid assembly of filaments of textile materials.

[0058] In pneumatic design, the choice of a homogeneous or hybrid assembly depends on the performance compromise sought for the resulting cable, in terms of stiffness, breaking strength, endurance, and industrial production cost.

[0059] Preferably, the filament strands are chosen from polyester strands, aliphatic polyamide strands, strands comprising aromatic polyamides or aromatic copolyamides and strands comprising mixtures of filaments of these materials, preferably chosen from aliphatic polyamide strands and more preferably made of nylon 6.6.

[0060] Advantageously, the tex rating of the cables is within the range [70; 250], more preferably the tex rating of the cables is within the range [90; 150]; the rating being the linear mass of the cable, that is to say the mass expressed in grams per thousand meters of cable.

[0061] Advantageously, a composite material is sewn with a first thread wound in a bobbin separate from a second thread threaded in a sewing needle so that the sewn composite material has one face with the first thread and a second face with the second thread.

[0062] This embodiment allows the stitching of the composite material to be adapted according to its environment and its interaction with other materials of the tire.

[0063] Advantageously, the reinforcements of the stitched composite material include a layer of an adhesive composition.

[0064] Advantageously, each bead comprising a layer of packing, axially external to the bead, and axially internal to the sidewall, said tire is characterized in that the composite material comprises the packing layer comprises the composite material.

[0065] Advantageously, the dynamic elastic stiffness modulus G* of the elastomeric blend of the stitched composite material is between 3 MPa and 55 MPa, G* being measured at 23 °C under alternating shear stress at a frequency of 10 Hz and at 10% strain. Brief description of the drawings

[0066] The present invention will be better understood upon reading the detailed description of embodiments taken by way of example, which are in no way limiting, and illustrated by the accompanying drawings in which: • Fig. 1 shows a schematic meridian section of a tire of the invention, with a padding layer 60 representing a stitched composite material. • Figure 2 shows, in view [Fig. 2]-A, a magnification of the tire bead from [Fig. 1]. In view [Fig. 2]-B, the profile 60, which corresponds to the padding layer 60 in the bead, has been extracted. During the extrusion phase, the profile 60 is extruded to a sufficient length, 98, to complete one revolution of the forming drum, as shown in [Fig. 2]-C. • In [Fig.3], we take up the previous [Fig.2]-B to illustrate two embodiments [Fig.3]-A and [Fig.3]-B. In [Fig.3]-A the seam is made in the thickness of the padding layer 60, and in [Fig.3]-B, the seam is made in the circumferential direction. • Figure 4 illustrates the stitching of a composite material in four steps [Fig.4]-A, 4-B, 4-C, and 4-D. • Figure 5 illustrates the production of the threads used for sewing in the composite material. Fig. 5-A shows two strands 300 obtained, one by S-twisting and the other by Z-twisting of strands composed of textile filaments. Fig. 5-B shows the principle of cable manufacturing textiles, for example, by overtwisting two yarns in a Z shape, which are then twisted in the opposite direction in an S shape to obtain a cable. Detailed description of the invention

[0067] The invention has been studied more particularly for a standardized passenger car tire designation, according to the ETRTO (European Technical Organisation for Wheels and Tyres) specification standard, 245 / 45 RI8 100W.

[0068] In the various figures, identical or similar elements bear the same reference numerals. Given the symmetry of the tread, for the sake of readability of the figures, the elements are referenced only once on one side of a meridian plane.

[0069] In [Fig. 1], the tire 1 comprises a carcass reinforcement 90 made of reinforcements coated with a rubber compound, and two beads 50 each having annular reinforcing structures 51 which hold the tire 1 onto the rim 100. The carcass reinforcement 90 is anchored in each of the beads 50. The tire 1 further comprises a crown reinforcement 20 comprising two working layers 21, 22, and a reinforcement layer 23. Each of the working layers 21 and 22 is reinforced by wire reinforcing elements which are parallel in each layer and crossed from one layer to the other, making angles with the circumferential direction between 10° and 70°. The reinforcement layer 23, arranged radially outside the top reinforcement 20, this reinforcement layer 23 being formed of circumferentially oriented and spirally wound reinforcing elements.A tread 10 is radially laid on the compression layer 23; it is this tread 10 that ensures the contact of the tire 1 with the road surface. The tire 1 shown is a tubeless tire: it comprises an inner rubber compound 95, impermeable to inflation gas, covering the inner surface of the tire. Each bead 50 comprises a layer of elastomeric compound 80 positioned radially on the innermost side and intended to be in contact with the rim 100, a layer of elastomeric compound filling 70, positioned at least in part between the main part 52 of the carcass reinforcement 90 and the inversion 53. The bead 50 also comprises a lateral filling layer 60 axially external to the inversion 53 and axially internal to the sidewall 30. Still on [Fig.1], the reference 49 surrounds the portion of the tire which corresponds to the lower zone 55.

[0070] In [Fig. 2]-A, the lower zone 55 of the tire is shown, with a bead 50 which partially comprises a carcass reinforcement 90 which has a main part 52, then wraps around a bead 51 to form a inversion 53. A first layer of padding 70 is positioned between the main part 52 of the carcass reinforcement 90 and its inversion 53. Depending on the modes of In its construction, the bead 50 may include a second lateral reinforcement padding layer 60, positioned axially externally to the inversion 53, and axially internally to the side layer 30. Axially furthest internally to the bead 50, a waterproof layer 95 constitutes the inner wall in contact with the internal inflation air.

[0071] Said bead 50 also includes a protective layer 80 which is in external axial contact with a portion of the rim 100 so as to limit the axial displacement of the bead. Said protective layer 80 also includes a portion intended to be in contact with the rim at the rim seat 100. A sidewall layer 30 cooperates with the bead 50 and constitutes an external lateral wall.

[0072] Fig.2-B is a magnification of the packing layer 60 which shows its profile in a meridian plane, and Fig.2-C shows it at the extrusion exit to then be placed flat on a tire manufacturing drum.

[0073] Starting from the extruded profile of [Fig. 2]-C, an additional step is implemented to reinforce the stuffing layer by stitching threads 200 and 210 according to a first embodiment, [Fig. 3]-A, and a second embodiment in [Fig. 3]-B. The two embodiments differ in the orientation of the stitching threads. In these embodiments, thread 210, wound onto the spool 260, is visible on one face of the stuffing element after stitching, and a second thread 200 is visible on another face. Reference numeral 220 in [Fig. 3]-A represents the spacing between two stitch lines, and reference numeral 230 represents the spacing between two stitch points.

[0074] Fig. 4, with views [Fig. 4]-A, 4-B, 4-C, and 4-D, are of different stages of a A possible sewing phase implemented after the extrusion of a stuffing profile 60, as shown in [Fig. 2]-C. In the first step ([Fig. 4]-A), the thread 200, threaded through the needle 230 via the opening 240, is carried through the profile by the needle 230, forming a loop. Then, [Fig. 4]-B, the bobbin hook 250 catches the loop of thread 200, and the bobbin 220 rotates to pass it around itself, [Fig. 4]-C. The hook 250 releases the thread 200, thus forming a loop around the bobbin thread 220, trapping it. Finally, the stitch tightens when the needle 230 rises and the feed dogs pull the profile, [Fig. 4]-D, to form a stitch 280.

[0075] The invention is not limited by the stitching principle described above. Other stitching methods are possible.

[0076] Figure 5 illustrates the production of the threads used for sewing in the material composite. Fig. 5-A shows two strands 300 obtained, one by S-twisting and the other by Z-twisting of strands composed of textile filaments. Fig. 5-B shows the principle of textile cable manufacturing, with, for example, the overtwisting of Two Z-shaped strands are then twisted in the opposite direction into an S-shape to form a cable. The cable's diameter PHI is shown.

[0077] Several tire configurations of the invention were tested to clearly demonstrate the performance benefits of the invention. The results of these tests were compared to those obtained for a control tire. The same size was used for both the control tire and the tires of the invention: 245 / 45R18 100W. This tire is designed to carry a load of 800 kg with an inflation pressure of 290 kPa.

[0078] The witness T is a conventionally designed tire not using stitched composite material.

[0079] The first PI tire, according to the invention ([Fig.3]-B) differs from the witness T in that it comprises a padding layer sewn with a thread composed of two strands of PET, each with a count of 114 tex. The direction of the stitching is radial.

[0080] The stitching of the stuffing layer is achieved by a stitching thread oriented according to its thickness as shown in [Fig.3]-B. The pitch between two stitching points is 2 mm, and the stitching thread density is 50 threads per decimeter.

[0081] The second pneumatic P2 of the invention is identical to PI, except that the direction of the stitching threads is circumferential ([Fig.3]-C).

[0082] Table [1]: CRRT (%) Drift stiffness (%) T 100 100 PI 104 109 P2 102 102

[0083] The abbreviation CRRT is the resistance coefficient, based on 100 for the reference tire. For PI and P2 tires, the variation is evaluated relative to the reference tire's base of 100. The same is done for the transverse drift stiffness.

[0084] It is easily verified that the tires PI, and P2 are indeed covered according to the invention.

[0085] Rolling resistance and drift stiffness were simulated by the finite element method for tires of the invention and the prior art according to the two configurations. The results are shown in Table 1.

[0086] A result greater than (respectively less than) 100% means an improvement (respectively a degradation) of the performance considered.

[0087] This example confirms that the tires of invention PI, and P2 with a layer of padding sewn with textile thread into the bead provide a solution to advantageous compromise in rolling resistance and drift rigidity and therefore in road handling.

[0088] The examples presented here are not exhaustive. The invention also works for tires with a non-reversible carcass reinforcement.

Claims

Demands

1. A motor vehicle tire (1) comprising in a meridian plane: two beads (50) intended to be mounted on a rim, two sidewall layers (30) connected to the beads (50), a vertex (20) comprising a tread (10), said vertex (20) having a first side connected to the radially outer end of one of the two sidewall layers (30) and having a second side connected to the radially outer end of the other of the two sidewall layers (30);at least one carcass frame (90) extending from the two bead ribs (50) to the top (20), the carcass frame (90) comprising a plurality of carcass reinforcement elements and being anchored in the two bead ribs (50) to a rod (53), characterized in that said tire (1) comprises at least one composite material consisting of an elastomeric blend comprising threads sewn into said elastomeric blend to form reinforcements oriented along stitching directions.;

2. Pneumatic (1) according to the preceding claim, wherein the composite material is stitched along a seam such that the distance between two consecutive stitch points is between 1 mm and 50 mm.

3. Pneumatic (1) according to claim 2, said pneumatic (1) in which the composite material is stitched along a seam such that the distance between two consecutive stitch points is constant.

4. Pneumatic (1) according to claim 2, wherein the composite material is stitched along a seam such that the distance between two consecutive stitch points is variable.

5. Pneumatic (1) according to any one of the preceding claims, wherein the composite material is stitched along a seam such that the distance between two consecutive stitch lines is variable, a stitch line being a succession of stitches along a given direction.

6. Pneumatic (1) according to any one of the preceding claims, wherein the composite material is stitched along a seam such that the distance between two consecutive stitch lines is constant, a stitch line being a succession of stitches in a given direction.

7. Pneumatic (1) according to any one of claims 5 to 6, the thread density of a stitched composite material being the number of stitch lines per decimeter, measured in the orthogonal direction of said stitch threads of said composite material, said pneumatic (1) is characterized in that the composite material has a thread density between 15 threads per decimeter and 150 threads per decimeter.

8. Pneumatic (1) according to any one of the preceding claims, wherein the sewing threads are textile cables, each cable being obtained by twisting N strands of a textile material with a twist T2 in a given direction D1 (respectively direction S or Z), with N>1, each strand resulting from overtwisting a twist T1 of a yarn of said textile material, in an opposite direction D2 (respectively Z or S).

9. Pneumatic (1) according to claim 8, wherein the number N of strands of a textile cable is between 1 and 6, and preferably N= 2.

10. Pneumatic (1) according to any one of claims 8 to 9, wherein the strands are made up of a homogeneous assembly of filaments of a textile material.

11. Pneumatic (1) according to any one of claims 8 to 9, wherein the strands are made up of a hybrid assembly of filaments of textile materials.

12. Pneumatic (1) according to any one of claims 8 to 11 wherein the strands are selected from polyester strands, aliphatic polyamide strands, strands comprising aromatic polyamides or aromatic copolyamides and strands comprising mixtures of filaments of these materials, preferably selected from aliphatic polyamide strands and more preferably made of nylon 6.

6.

13. Pneumatic (1) according to any one of claims 8 to 12, wherein the tex count of the cables is in the range [70; 250], more preferably the tex count of the cables is in the range [90; 150]; the count being the linear mass of the cable, i.e. the mass expressed in grams per thousand meters of cable.

14. Pneumatic (1) according to any one of the preceding claims, wherein a composite material is sewn with a first thread (210) wound onto a bobbin (220) separate from a second thread (200) threaded onto a sewing needle (230) such that said material The stitched composite has one face with the first thread (200) and a second face with the second thread (210).

15. Pneumatic (1) according to any one of the preceding claims, wherein the reinforcements of the composite material comprise a layer of an adhesive composition.

16. Tire (1) according to any one of the preceding claims, each bead (50) of a tire (1) comprising a packing layer (60), axially external to the bead (53), and axially internal to the sidewall (30), said tire (1) is characterized in that the packing layer (60) comprises the composite material.

17. Pneumatic (1) according to the preceding claim, wherein the dynamic elastic stiffness modulus G* of the elastomeric blend of the stitched composite material is between 3 MPa and 55 MPa, G* being measured at 23°C under alternating shear stress at a frequency of 10 Hz and at 10% strain.

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