Tyre comprising a flexible tread

Abstract

The present invention relates to a tyre (1) comprising a tread (6) joined via two sidewalls (7) to two beads (4), a composite layer (9) formed of reinforcers (100) parallel to one another, and coated in an elastomeric compound, forming a carcass reinforcement (2) wrapped, in each bead (4), around a bead wire (8) in order to produce a turn-up, said composite layer (9) extending radially to the outside of the carcass reinforcement (2) in order to form a crown reinforcement (5) comprising two crown layers (51, 52) radially superposed to the inside of the tread (6), the reinforcers (100) of the composite layer (9) are connected by weft filaments (110) such that the reinforcers and the weft filaments (110) form a woven fabric of which the weft-filament density is at least equal to half the density of the reinforcers of the woven fabric.

Description

Pneumatic tire with a flexible tread

[0001] The present invention relates to a bicycle tire, designed to have a carcass reinforcement and a crown reinforcement optimized for performances such as puncture resistance, and while having a minimized manufacturing cost, in comparison to conventional designs.

[0002] Furthermore, the invention applies to all types of bicycles or bikes, such as road bikes, mountain bikes (mountain bikes), hybrid bikes (hybrid bikes), bikes with motors, for example electric. The invention also applies to tubeless type tires, i.e. mounted directly on a rim without an inner tube, or to "tube-type" type tires requiring the presence of an inner tube.

[0003] By convention, we consider a reference (O, OX, OY, OZ), whose center O coincides with the center of the tire, the circumferential directions OX, axial OY, and radial OZ respectively designate a direction tangent to the rolling surface of the tire according to 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.

[0004] By radially inner, respectively radially outer, we mean closer, respectively further from the axis of rotation of the tire.

[0005] Axially inner, respectively axially outer, means 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 tire tread and perpendicular to the axis of rotation of the tire.

[0006] The construction of a 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 by the axisymmetry of the geometry of the tire around its axis of rotation. The tire also includes a plane of symmetry orthogonal to the axis of rotation and passing through the center of the tread: this is the equatorial plane.

[0007] Usually, a tire comprises a tread intended to be in contact with a ground, radially internally a crown reinforcement. The crown reinforcement The crown and tread constitute the crown of the tire. A carcass reinforcement radially inward to the crown reinforcement provides the tire with the strength needed to carry the intended load.

[0008] An elastomeric blend is an elastomeric material obtained by mixing its various constituents. An elastomeric blend typically comprises an elastomeric matrix with at least one diene elastomer of natural or synthetic rubber type, at least one reinforcing filler of carbon black type and / or silica type, a crosslinking system most often based on sulfur, and protective agents. For certain applications, the elastomers considered may also include thermoplastics (TPE).

[0009] The expression "based on" composition means a composition comprising the mixture and / or the 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 manufacture of the composition, in particular during its crosslinking or vulcanization.

[0010] By the expression "part by weight per hundred parts by weight of elastomer" (or pce), it is meant, within the meaning of the present invention, the part, by mass per hundred parts of elastomer present in the rubber composition considered.

[0011] An elastomeric mixture can be characterized mechanically, in particular after curing, by its dynamic properties, such as a dynamic shear modulus G*= (G'2+G” 2)1 / 2, where G' is the elastic modulus of shear stiffness and G” 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 type viscoanalyzer, according to the ASTM D 5992-96 standard. The response of a sample of vulcanized elastomeric mixture to a sinusoidal stress in alternating simple shear is recorded, at a frequency of 10Hz, at a temperature of 100°C. A strain amplitude sweep is carried out from 0.1% to 50% (forward cycle), then from 50% to 0.1% (return cycle). For the outward cycle, we indicate the maximum value of tan(ô) observed, noted Tan(ô) ma x. Prior art

[0012] A bicycle tire must meet very varied demands depending on its intended use. The user of an urban bicycle, or a mountain bike, has expectations related to their specific use, however, performance such as puncture resistance, pinch flats, or even the tire's waterproofness are expectations common to all users.

[0013] Furthermore, bicycle tire users have in common the desire to maximize the efficiency of their tire, which is the tire's ability to restore the energy supplied by the cyclist under riding conditions. In other words, it is the ratio between the energy restored under riding conditions, divided by the energy supplied by the cyclist.

[0014] This performance will depend on several factors, including the tread pattern, rolling resistance, and inflation pressure. Performance also depends on the choice of materials used and the tire's architecture.

[0015] Tire architecture refers to the stacking of profiles, layers of materials, and their relative positioning to produce a tire that meets a given technical and industrial performance specification. The design of the architecture often takes place through successive iterations with performance simulation phases.

[0016] According to a first known design, in the case of a carcass reinforcement comprising a single carcass layer, the free ends of each turn-up may extend to the crown of the tire, at which point they are positioned radially inside the tread and radially outside the carcass layer; in addition, they are radially superimposed on each other, so as to form a partial overlap of the two turns. In an overlap-type design, an additional reinforcing layer, connecting the two beads together, may be positioned between the carcass layer and its turns. For example, such an additional layer may be made of a nylon fabric. This additional reinforcement has the effect of improving the resistance of the carcass reinforcement to punctures and cuts, as well as to pinch impacts.

[0017] According to a second known design, each bead comprises a filling element made of an elastomeric mixture, extending radially outside the bead wire and axially between the carcass layer and its upturn. The axial direction being the direction of the tire's axis of rotation, "axially inner, respectively outer" means "closer, respectively further, from the equatorial plane of the tire, in the axial direction", the equatorial plane of the tire passing through the middle of the tread and being perpendicular to the tire's axis of rotation. Such a filling element stiffens the bead. By its deformation capacity and by the decoupling it induces between the carcass layer and its upturn, it also makes it possible to better absorb the deformation energy generated by a pinch impact. Consequently, it is a solution which also improves resistance to pinch impacts.

[0018] According to a third known design, the carcass reinforcement of a bicycle tire is made up of at least two carcass layers wrapped in each bead, from the inside to the outside, around a bead wire, to form a turn-up. Preferably, the reinforcements of a carcass layer are crossed from one carcass layer to the next, forming, with the circumferential direction of the tire, an angle equal to 45°. The free ends of the respective turn-ups of each carcass layer are radially superimposed, radially inside the tread, at the crown, to form an overlap. In addition, each bead comprises a filling element made of an elastomeric mixture, extending radially outside the bead wire and axially between the axially outermost carcass layer and the corresponding axially innermost turn-up.The combination of a carcass reinforcement comprising at least two carcass layers and a filling element in each bead provides advantageous resistance to pinching impacts.

[0019] Document EP3797040B1 relates to a bicycle tire comprising an anti-puncture system consisting of a tread comprising a protective layer capable of providing resistance to the penetration of foreign bodies.

[0020] However, there is a need to simplify the design of iso-performance bicycle tires while lowering industrial production costs.

[0021] The inventors set themselves the goal of simplifying the architecture of bicycle tires while improving endurance, more precisely puncture resistance, without reducing industrial production costs.

[0022] This aim has been achieved by the design of a bicycle tire comprising a tread intended to be in contact with a rolling ground, said tread being joined by means of two sidewalls with two beads intended to be in contact with a rim, a composite layer formed of reinforcements parallel to each other, making with a circumferential direction an angle ranging from 40° to 60°, preferably between 40° and 60° and coated in an elastomeric mixture, forming a carcass reinforcement by winding in each bead around a bead wire to produce a turn-over, said composite layer extending radially outside the carcass reinforcement to form a crown reinforcement comprising two crown layers radially superimposed inside the tread, and resulting from the overlap of the ends of said composite layer,said tire is characterized in that the parallel reinforcements of the composite layer are connected by weft threads so that the parallel reinforcements and the weft threads form a woven fabric whose density of weft threads is at least equal to half the density of the reinforcements of the woven fabric, the density of threads or reinforcements being the number of threads or reinforcements per decimeter.,

[0023] Any interval of values ​​designated by the expression "between a and b" represents the domain of values ​​from more than a to less than b (i.e., excluding the limits a and b), while any interval of values ​​designated by the expression "from a to b" means the domain of values ​​from a to b (i.e., including the strict limits a and b).

[0024] The architecture of the tire of the invention has been simplified to the point that a single composite layer forming a woven fabric constitutes both the carcass reinforcement and the crown reinforcement. The overlap of the two ends of the composite layer in woven fabric, radially superimposed, forms the crown reinforcement.

[0025] The density of the reinforcements of the composite layer is determined by counting the number of parallel reinforcements per decimeter in the direction normal to that defined by the parallel reinforcements. Similarly, the density of the weft threads of the composite layer is determined by counting the number of weft threads per decimeter in the direction normal to the direction of the weft threads. The direction of the weft threads is oblique to that of the reinforcements and preferably orthogonal to the direction of the reinforcements.

[0026] The combination of the "overlap" architecture of a bicycle tire and the use of a woven fabric with a high density of weft threads are at the heart of the invention. A high density of weft threads means a number of threads per decimeter significantly higher than usual practice, being at least equal to half the number of reinforcements per decimeter. In this way, the advantages of these two technologies are combined to gain both in simplification of the tire architecture and in industrial production costs.

[0027] Innovative and unexpected technical effects confer advantageous properties to the tires of the invention. The "overlap" architecture leads to a crown reinforcement with at least three passes of the composite layer under the crown, and two passes at the sidewalls. The woven fabric of the composite layer comprises weft threads which have a count greater than 10 tex, but above all, said weft fabric can comprise a density of weft threads greater than half the density of the reinforcements.

[0028] With a high density of weft threads, the composite layer that forms both the carcass reinforcement and the crown reinforcement constitutes a sort of effective mesh to protect the crown against perforations. This protective mesh is found on the transverse walls of the tire by the sidewalls where the composite layer passes twice due to the "overlap" architecture.

[0029] An example of reinforcement used is a nylon cable formed from a single strand with a count of 47 tex. This cable is used to form a fabric with 160 reinforcements per decimeter. The density of weft threads in this example is also 160 threads per decimeter.

[0030] There are two main methods for obtaining composite fabrics used in tire design. There are fabrics resulting from the direct calendering of a network of parallel and equidistant reinforcements, which consists of applying a layer of elastomeric mixture on either side of the network of parallel reinforcements to obtain a composite layer. This is the so-called "straight grain" method.

[0031] Another approach is to connect the reinforcements with a weft yarn, often orthogonal to the direction of the 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.

[0032] 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. To obtain a fabric, the textile must undergo a treatment including a sizing and drying phase, then a thermomechanical treatment before the final calendering step. Using the textile in the form of a woven fabric facilitates these different manufacturing steps.

[0033] But in the case of the bicycle tires of the invention, the woven fabric is characterized by a high density of weft threads and contributes to the mechanical behavior of the carcass and crown reinforcements. This additional contribution of rigidities in the plane of the woven composite layer makes it possible to simplify the architecture of the tire by removing certain layers of materials used in usual design based on straight-grain fabrics. This results in a significant reduction in the mass of the tire which translates into a reduction in the material cost directly perceptible on the industrial cost price of the tire.

[0034] A mass gain of 16% is observed on the mass of a tire of the invention.

[0035] The combination of the main characteristics of the invention, namely the choice of the "overlap" architecture combined with the use of a high density woven fabric, leads to the tire of the invention which solves the technical problem stated above.

[0036] Other characteristics of the invention linked to the nature of the woven fabric both on the reinforcements and on the weft thread, combined with the “overlap” architecture, make it possible to further optimize the compromise between the technical and industrial performances of the tires of the invention.

[0037] Advantageously, the weft yarn has a count ranging from 10 tex to 60 tex, preferably between 10 tex and 60 tex. The use of cotton weft yarn is the classic situation encountered in the trade of woven fabrics. For technical and economic reasons, it is advantageous for the weft yarn to be made of a material of the same nature as the reinforcements, which means that the textile used to constitute the weft yarn and the reinforcement is the same. In the example cited above, with a nylon reinforcement of 47 tex, the weft yarn is also made of nylon but possibly with a different count.

[0038] Another surprising result is the improvement of the tire's sealing to retain the internal inflation air, so that the internal sealing layer, usually made of a butyl material, can be removed from the architecture of a tire of the invention. Indeed, the inventors have observed that the elastomeric mixture coating layer of the composite layer ensures effective sealing of the internal inflation air. Therefore, advantageously, the coating mixture of the reinforcements of the composite layer constitutes the internal sealing layer in the tire cavity.

[0039] Thanks to the "overlap" architecture, advantageously, the crossed working crown layers are formed by the overlap of the axial ends of the composite layer forming the crown reinforcement. This superposition of woven composite layers under the crown, namely the passage of the carcass layer and the overlap of the axial ends of the composite layer, reinforces the crown of the tire against perforations. In conventional designs without woven fabrics, a protective layer is added to the crown, but in the context of this invention this addition is no longer necessary as a general rule. However, for very specific uses where the tires are particularly stressed, for example on off-road paths, it is advantageous for the crown reinforcement to comprise at least one protective composite layer, arranged radially outside the crown reinforcement and radially inside the tread.

[0040] Advantageously, the protective composite layer is made of the same material as the composite layer forming the crown reinforcement. This means that all the elements constituting the composite layer are identical to those of the protective composite layer (nature of reinforcements, nature of weft threads, counts, twist, densities, nature of the coating mixture, thickness of the layers, etc.). In this embodiment, the interest is to standardize the materials used to save on material costs.

[0041] Another benefit of the overlap architecture is visible through the sidewalls. Advantageously, each sidewall comprises at least two composite layers. As a result, the lateral protection of the tires of the invention is reinforced.

[0042] Advantageously, the bead is made of a metallic material. There are two categories of tires whose appearance depends on the nature of the bead. A first category of tires is made with metallic bead, consisting of a winding of a metal wire, the number of turns being a function of the size and use of the tire and in particular its operating pressure. These tires are then presented in their final form, that is to say a tire forming a torus and therefore of a significant size when it comes to transport or storage.

[0043] For a second category of tire, the bead is made of a textile material. To simplify the storage and transport of bicycle tires, a second category of tires has been proposed that can be folded to limit their bulk. Such tires are made with textile material beads that can be elastically deformed without disrupting their performance when they return to their original shape. Preferably, the bead is made of an aromatic polyamide material.

[0044] Advantageously, the composite woven layer forming the carcass reinforcement, and the crown reinforcement has a circumferential length ranging from 1200 mm to 2000 mm, preferably between 1200 mm and 2000 mm, and has an axial width ranging from 120 mm to 450 mm, preferably between 120 mm and 450 mm.

[0045] The circumferential length of the composite layer is defined as its unrolling in the circumferential direction before being laid on the manufacturing drum. Similarly, the axial width corresponds to its axial extent.

[0046] The inventors have pushed the standardization of materials used to manufacture a tire to the maximum. With only a surface area of ​​woven composite fabrics ranging from 0.144 m 2 at 0.9 m 2 , preferably between 0.144 m 2 and 0.9 m 2 , a tire of the invention can be assembled. When the tire has a protective layer, this same woven composite fabric can be used.

[0047] Preferably, the reinforcements of the composite layer are textile cables, each cable being obtained by twisting a twist T2 of N strands of a textile material 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).

[0048] The raw material used in the manufacture of a textile cable is the yarn stored by winding on reels of 4 to 12 kg. It is a flat wick composed of continuous elementary filaments, identical in both appearance and properties. mechanical, the said roving comes directly from the spinning installations. A yarn is generally defined by the nature of the material which constitutes the filaments (PET, Nylon, Rayon, Aramid); its linear mass which is expressed in tex and which represents the mass in grams of 1000 m of yarn; the number of elementary filaments constituting the yarn (200 to 1500), and the degree of intermingling of the elementary filaments.

[0049] From the yarns, double-twisted textile cables (Tl, T2) are produced, which are prepared by a process called twisting in which: - during a first stage, the overtwisting, each yarn or multifilament fiber (in English "yarn") constituting the final cable is first of all 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 English "strand") in which the elementary filaments are subjected to a helical deformation around the fiber axis (or axis of the strand); - then, during a second stage, twisting, several strands, generally two, three or four in number, of identical or different natures in the case of so-called hybrid or composite cords, are then twisted together according to a final twist T2 (which may be equal to or different from Tl) in the 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 cord or final assembly with several strands.

[0050] The role of twisting is to adapt the material properties in order to create transverse cohesion of the reinforcement, improve endurance to compressive stresses and distribute the stresses over all the filaments. This step of the twisting process is accompanied by a decrease in breaking strength and longitudinal modulus and an increase in fatigue endurance with increasing twist. Ultimately, the process is parameterized to achieve a compromise between fatigue resistance and breaking strength.

[0051] The cable production process continues with a gluing phase to ensure the bond between the cable and the surrounding elastomeric mixture. The quality of the textile / mixture interface influences the fatigue performance of the glued cable.

[0052] Advantageously, the number N of strands of a textile cable ranges from 1 to 6, preferably between 1 and 6 and more preferably N = 1. An example of such a cable is N 47 / 1, which means that the cable is composed of the assembly of a Nylon strand with a 47 tex count.

[0053] When N=2, an industrial direct cabling process allows overtwisting and twisting to be carried out in a single manufacturing step, resulting in a significant gain in productivity. On the other hand, when N=3, overtwisting and twisting are carried out in two separate operations to produce 3-strand constructions.

[0054] Advantageously, the yarns are made of a hybrid assembly of filaments of textile materials such as an aliphatic polyamide, a polyester, a rayon, an aromatic polyamide. Advantageously, the count of the aliphatic polyamide (Nylon) cables making up the woven composite layer is greater than or equal to 10 tex, preferably greater than or equal to 14 tex, and even more preferably greater than or equal to 47 tex, the count being the linear mass of the cable, i.e. the mass expressed in grams per thousand meters of cable.

[0055] Other advantageous details and characteristics of the invention will emerge below from the description of the exemplary embodiments of the invention with reference to the figures which represent meridian views of diagrams of a tire according to embodiments. The figures are not shown to scale to simplify understanding.

[0056] Figure 1 includes a view 1-A which shows a section of a tire of the invention in a meridian plane, and a view 1-B which represents an enlargement of a woven fabric.

[0057] Figure 2 shows an embodiment of the invention with the presence of a protective layer in the crown reinforcement.

[0058] Figure 3 is a schematic diagram of the weaving process to obtain the high density weft yarn fabric of the invention.

[0059] Figure 4 includes two views 4-A and 4-B showing the principle of producing the reinforcements of the woven composite fabric of the invention. Figure 4-A illustrates the overtwisting of two aramid yarns to form two strands by illustrating the two possible directions “S” or “Z” overtwisting. Figure 4-B shows the twisting of the two preceding strands to form a cable, used in a composite fabric of the invention.

[0060] The invention was implemented on a tire of dimension 25-622, according to the specification standard of ETRTO (European Technical Organization for Rims and Tires).

[0061] In Figure 1-A, the general reference tire 1 comprises a composite layer 9 which forms a carcass reinforcement 2 and a crown reinforcement 5 with two crown layers (51, 52). The carcass reinforcement 2 consists of a first carcass layer which wraps around a bead wire 8 in each bead 4 so as to form a loop, then extends into the crown reinforcement 5 to form crown layers (51, 52) consisting of the axial ends of the composite layer 9. The beads 4 are connected to the tread 6 via two sidewalls 7.

[0062] Figure 1-B shows a piece of woven fabric with the textile reinforcing threads 100 connected orthogonally by woven threads 110.

[0063] Figure 2 is an embodiment of the invention where a protective layer 10 reinforces the crown reinforcement 5, positioned radially outside the crown layers.

[0064] Figure 3 shows the principle of the general reference weaving process 200 to obtain the woven fabric 9. The cable reels 220 are installed in the creel 210 which, after unwinding the cables, makes it possible to obtain a network of parallel cables 100. A cable separation system 250 precedes the passage through the comb 240 for the insertion of the weft threads 110. The particularity here is to have, on the one hand, a high density of weft threads which is greater than half the density of cables of the fabric, and on the other hand the weft threads and the cables are of the same nature.

[0065] Figure 4 shows views 4-A and 4-B. View 4-A shows two strands obtained, one by an S-shaped overtwisting, and the other by a Z-shaped overtwisting of yarns composed of bundles of textile filaments.

[0066] Figure 4-C illustrates the principle of manufacturing textile cable, for example, overtwisting two Z-shaped yarns, which are then twisted in the opposite direction in an S-shape to obtain a cable.

[0067] The dimensional data of the tire, produced in accordance with the invention, have a sidewall height of 35 mm, and a flange width of 25 mm. The angles of the reinforcements of the crown layers with the circumferential direction vary from 40° to 60°. The bead wire is made of textile with an assembly of 18 Aramid threads.

[0068] The tire is used with an inflation pressure of 800 kPa.

[0069] The composite layer constituting the carcass and crown reinforcements is made of Nylon 6.6 reinforcements with a count of 47 tex. These Nylon reinforcements are cables formed from a single strand. Their breaking force is equal to 2.3 daN at 23% elongation, and the cable density of a composite layer is 40 threads per inch. The diameter of the cables is 39 hundredths of a millimeter, and the composite layer has a thickness of 0.41 mm. The weft threads connecting the cables are also made of Nylon with a count of 47 tex. The density of the weft threads of the wefted composite layer is 40 threads per inch.

[0070] For the tire size studied, the circumferential length of the composite layer forming the carcass and crown reinforcements is 1944 mm, and its axial width is 168 mm. These dimensions of the composite layer are sufficient to form both the carcass and crown reinforcements. These values ​​guarantee optimal functioning of the composite layer both as a carcass reinforcement and as a crown reinforcement.

[0071] The elastomeric coating mixture of the composite layer is a composition as described below in the following table:

[0072] [Table 1]

[0073] The coating mixture of the composite layer forming the carcass and crown reinforcement is characterized by the following mechanical properties:

[0074] [Table 2]

[0075] The thickness of the coating layer of the composite layer cables is less than or equal to 0.1 mm.

[0076] Tire configurations of the invention were tested to clearly highlight the performance provided by the invention. The results of these tests are compared with those obtained on a control tire of the same size, namely: 25-622.

[0077] Witness T is in accordance with the diagram in Figure 1-A and corresponds to a tire of usual design with an “overlap” architecture, but without woven fabric. This tire differs from the invention in that the composite layer forming the carcass reinforcement and the crown reinforcement is not a woven fabric, but a so-called straight-grain fabric.

[0078] First, an endurance test was carried out on each of the tires. This test consists of measuring the resistance to wear of a tire in contact with a rotating steering wheel, fitted with tension bars and subjected to cycles of stress in loads, pressure and speed.

[0079] The "breaking energy" test, also known as the polar test, involves inserting a polar into the sidewall of a tire inflated to the nominal pressure and mounted on a measuring rim. The force applied is measured at the point of sidewall rupture.

[0080] Rolling resistance tests were carried out according to the principles of ISO 28580. For a tested tire, the result is the rolling resistance coefficient which represents the ratio of the force resisting the vehicle's forward movement due to tire hysteresis divided by the load carried.

[0081] A leak test comparing the control and the tire of the invention was carried out. The test consists of mounting a tire on a rim, inflating it to a set pressure and monitoring the evolution of the internal pressure over time.

[0082] A result above (or below) 100% means an improvement (or deterioration) in the performance considered.

[0083] The results obtained are summarized in the following table: (0084} [Table 3]

[0085] The tires of the invention are at an identical level of performance in endurance, but they are distinguished from the state of the art by the advantageous compromise of performances other than endurance such as rolling resistance and especially the tightness to the leakage of internal inflation air, the mass and by a very significant gain in industrial cost price.

[0086] The invention can also be applied, for example, to motorized two-wheeled vehicles, wheelchairs or strollers.

Claims

CLAIMS 1. A tire (1) for a bicycle comprising a tread (6) intended to be in contact with a rolling surface, said tread (6) being joined by means of two sidewalls (7) to two beads (4) intended to be in contact with a rim, a composite layer (9) formed of reinforcements (100) parallel to each other, making with a circumferential direction an angle ranging from 40° to 60°, and coated in an elastomeric mixture, forming a carcass reinforcement (2) by winding in each bead (4) around a bead wire (8) to produce a turn-over, said composite layer (9) extending radially outwardly to the carcass reinforcement (2) to form a crown reinforcement (5) comprising two crown layers (51, 52) radially superimposed internally to the tread (6), and resulting from the overlapping of the ends of said composite layer (9),said tire (1) is characterized in that the parallel reinforcements (100) of the composite layer (9) are connected by weft threads (110) so that the parallel reinforcements (100) and the weft threads (110) form a woven fabric whose density of weft threads is at least equal to half the density of the reinforcements of the woven fabric, the density of threads or reinforcements being the number of threads or reinforcements per decimeter., 2. Tire (1) according to claim 1, in which the weft thread (110) has a count ranging from 10 tex to 60 tex, and preferably between 10 tex and 60 tex.

3. Tire (1) according to any one of the preceding claims, in which the coating mixture of the reinforcements (100) of the composite layer (9) constitutes the internal sealing layer in the cavity of the tire (1).

4. Tire (1) according to any one of the preceding claims, in which the crown reinforcement (5) comprises at least one composite protective layer (10), arranged radially outside the crown reinforcement (5), and radially inside the tread (6).

5. Tire (1) according to claim 4, in which the protective composite layer (10) is made of the same material as the composite layer (9) forming the crown reinforcement (5).

6. Tire (1) according to any one of the preceding claims, in which each sidewall (7) comprises at least two composite layers.

7. A tire (1) according to any one of claims 1 to 6, wherein the bead wire (8) is made of a metallic material.

8. A tire (1) according to any one of claims 1 to 6, wherein the bead wire (8) is made of a textile material.

9. A tire (1) according to claim 8, wherein the bead wire (8) is made of an aromatic polyamide material.

10. Tire (1) according to any one of the preceding claims, in which the composite layer (9) formed by weaving the carcass reinforcement (2), and the crown reinforcement (5) has a circumferential length ranging from 1200 mm to 2000 mm, preferably between 1200 mm and 2000 mm.

11. Tire (1) according to any one of the preceding claims, in which the composite layer (9) formed by weaving the carcass reinforcement (2), and the crown reinforcement (5) has an axial width ranging from 120 mm to 450 mm, preferably between 120 mm and 450 mm.

12. Tire (1) according to any one of the preceding claims, in which the reinforcements (100) of the composite layer (9) are textile cables, each cable being textile obtained by twisting a twist T2 of N strands of a textile material 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).

13. Tire (1) according to claim 12, in which the number N of strands of each textile cable is from 1 to 6, preferably between 1 and 6, and more preferably N is equal to 1.

14. Tire (1) according to any one of claims 12 to 13, in which the yarns are made up of a hybrid assembly of filaments of textile materials such as an aliphatic polyamide, a polyester, a rayon, an aromatic polyamide.

15. Tire (1) according to any one of claims 12 to 14, in which the count of the aliphatic polyamide (Nylon) cables making up the woven composite layer (9) is greater than or equal to 10 tex, preferably greater than or equal to 14 tex, and even more preferably, greater than or equal to 47 tex, the count being the mass linear mass of the cable, that is to say the mass expressed in grams per thousand meters of cable.

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