EP3086953A1

EP3086953A1 - Tire including a set of one or more knitted fabrics

Info

Publication number: EP3086953A1
Application number: EP14802907.7A
Authority: EP
Inventors: Christophe Le Clerc; Richard CORNILLE; Geneviève PINEAU; Xavier Legrand; Hubert OSTYN; Marc-Antoine COLOT; Guillaume TANCHAUD
Original assignee: Michelin Recherche et Technique SA Switzerland; Compagnie Generale des Etablissements Michelin SCA; Michelin Recherche et Technique SA France
Current assignee: Compagnie Generale des Etablissements Michelin SCA
Priority date: 2013-12-26
Filing date: 2014-11-27
Publication date: 2016-11-02
Also published as: CN105848928B; US20160325589A1; WO2015096951A1; CN105848928A; FR3015929A1

Abstract

The invention relates to a tire (10) which includes at least one set (45) of at least two layers of at least one knitted fabric (44₁, 44₂), the two layers being at least partially vertically adjacent. The knitted fabric (44₁, 44₂) includes: columns of loops arranged, one after the other, substantially in a so-called "main" general direction (X1); and rows of loops arranged, one beside the other, substantially in a so-called "transverse" general direction (Z1). The knitted fabric (44₁, 44₂) has a force no higher than 40 N × rows^-1 and/or 40 N × columns^-1 when 100% elongated. The force when 100% elongated is predetermined on the basis of a force/elongation curve obtained by applying ISO standard 13934-1:2013 to the or each knitted fabric (44₁, 44₂) embedded in the standard elastomer matrix, and the number of rows and/or columns is measured according to NF EN standard 14791.

Description

Pneumatic comprising an assembly of one or more knitwear

[001] The invention relates to a tire comprising an assembly of layers of one or more knits and a method of manufacturing such a tire.

[002] The invention applies to any type of vehicle but is preferably intended for passenger vehicles, two-wheeled vehicles such as a motorcycle or a bicycle, industrial vehicles chosen from vans, heavy vehicles such as "Heavy goods vehicles" - ie, metros, buses, road transport vehicles (trucks, tractors, trailers), off-the-road vehicles -, agricultural or civil engineering machinery, aircraft, other transport or handling vehicles.

[003] A state of the art tire known for a passenger vehicle comprising a carcass reinforcement anchored in two beads and radially surmounted by a crown comprising a crown reinforcement and a tread, the latter being joined to the beads. by two flanks.

[004] A constant objective of tire manufacturers is to increase the drift rigidity of the tire in order to improve the handling ("handling") of the tires, in particular during strong cornering stresses. For this purpose, several solutions have been implemented.

[005] A first solution is to provide the tire with a carcass reinforcement comprising two carcass plies. A second solution is to increase the thickness of the flanks. However, the rigidity of drift of the tire using the first solution remains perfectible and the mass of the tire using the second solution is relatively high.

[006] The object of the invention is to provide a tire having a rigidity of drift under the greatest possible stress, without, however, increasing the mass with respect to the tires using the first and second solutions described above.

[007] For this purpose, the subject of the invention is a tire comprising at least one assembly of at least two layers of at least one knit, the two layers being at least partially superposed on one another, the or each knit comprising: - columns of loops, the loops of one and the same column being arranged one after the other substantially in a so-called main general direction, - rows of loops, the loops of the same row being arranged next to each other substantially in a transverse general direction, the or each knit having a force at 100% elongation less than or equal to 40 N. row ¹ and / or 40 N. column ^"1 , the force at 100% elongation being determined from a force-elongation curve obtained by applying the standard ISO 13934-1: 2013 to the or each knit embedded in the standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971.

[008] By definition, a knit is a reinforcing element comprising stitches. Each mesh includes an interlaced loop with another loop. Thus, there is a knit which is a knitted fabric of a fabric which is a textile comprising weft yarns and warp yarns, the weft yarns being substantially parallel to one another and the warp yarns being substantially parallel to each other.

[009] There are knitted mesh (or knit weft) knit and jersey knit (or warp knit). In the gathered knit, the stitches are formed essentially in the direction in which the loops of the same row are arranged next to each other (depending on the width of the knit). In the knit jersey, the stitches are formed essentially in the direction in which the loops of the same column are arranged next to each other (depending on the length of the knit).

[010] Different contexts exist. By contexture means the interlacing mode of the son forming a repeating pattern on the knit. Among these contexts, and without these being limiting, we will quote the jersey, the quilted jersey, the coast 1 ^* 1, the English coast, the interlocked coast, the beaded coast for the knitted knitwear and the charmeuse, l atlas for discarded knitwear.

[011] With the assembly, the tire according to the invention has a high drift rigidity and greater than that of the tires of the first and second solutions while being lighter as demonstrated by the results of the comparative tests described below.

[012] The ISO 13934-1: 2013 standard indicates how to obtain the force-elongation curve of the or each knit of the tire according to the invention. The standard specifies precisely how to determine, from this force-elongation curve, the elongation at break and the maximum force, in particular the number of tests, the calculation and the expression of the results relative to these magnitudes. Those skilled in the art will also be able, from this force-elongation curve, to determine the forces at 100%, 50% and 10% elongation, to calculate and express the results relating to these quantities in an identical way. In particular, the force-elongation curve was produced on specimens having a width equal to 50 mm ± 0.5 mm and a length allowing a test length equal to 100 mm ± 1 mm.

[013] The standard elastomer matrix is a composition having an apparent MA100 modulus at 100% elongation (i.e., calculated with respect to the initial section of the specimen), measured according to ASTM D412 -1998, test tube "C", equal to 1.6 MPa ± 0.2 MPa, that is to say ranging from 1.4 to 1.8 MPa. The ISO 13934 1: 2013 standard indicates that measurements must be made on 2 sets of at least 5 test pieces. For each layer, each test piece is made by interposing each layer of knitted fabric in the fabric between two layers of the standard elastomer matrix. Each layer of the standard elastomer matrix has a thickness substantially equal to 0.4 mm. The test piece then formed by the knit layer and the two layers of the standard elastomer matrix is fired for 15 min at 160 ° C. under a pressure of 2.4 bar.

[014] The NF EN 14971 standard makes it possible to determine the number of columns and rows per unit length. Thus, a value of a characteristic (strength at 10%, 50%, 100% elongation and maximum force) is obtained per row by dividing the value obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in a standard elastomer matrix in the column direction by the number of rows per unit length multiplied by the width of the specimen. Similarly, the value of one characteristic per column is obtained by dividing the force obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in a standard elastomer matrix in the row direction by the number columns per unit length multiplied by the width of the specimen.

[015] In order to achieve the properties described below, the skilled person will vary some parameters of the or each knit as the contexture and some parameters of the manufacturing process of the or each knit as the type of trade used , the gauge of the trade and the greenhouse in the case of meshes picked.

[016] According to other preferred characteristics of the tire:

[017] The or each knit has a force at 100% elongation less than or equal to 35 N. row ^"1 and / or 35 N. column ^{" 1} , the force at 100% elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971. [018] - The or each knit has a force at 100% elongation greater than or equal to 0.5 N. row ^"1 and / or 0.5 N. column ^{" 1} , preferably 5 N. row ^"1 and or N. column ^"1 , more preferably 15 N. row ^{" 1} and / or 15 N. column ^"1 , the force at 100% elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard at or at each knit embedded in the standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971.

[019] According to other preferred features of the tire:

[020] - The or each knit has a force at 50% elongation greater than or equal to 0.5 N. row ^"1 and / or 0.5 N. column ^{" 1} , preferably 2.5 N. row ^{" 1} and / or 2.5 N. column ^"1 and more preferably 10 N. row ^{" 1} and / or 10 N. column ^"1 , the force at 50% elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971.

[021] - The or each knit has a force at 50% elongation less than or equal to 25 N. row ^"1 and / or 25 N. column ^{" 1} , preferably 20 N. row ^"1 and / or 20 N column ^"1 , the force at 50% elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971.

[022] According to other preferred features of the tire:

[023] - The or each knit has a force at 10% elongation greater than or equal to 0.05 N. row ^"1 and / or 0.05 N. column ^{" 1} , preferably 1 N. row ^"1 and / or 1 N. column ^"1 and more preferably 2 N. row ^{" 1} and / or 2 N. column ^"1 , the force at 10% elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard at or at each knit embedded in the standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971.

[024] - The or each knit has a force at 10% elongation less than or equal to 9 N. row ^"1 and / or 9 N. column ^{" 1} , preferably 7 N. row ^"1 and / or 7 N column ^"1 , the force at 10% elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971. [025] According to other preferred features of the tire:

[026] - The or each knit has a maximum force greater than or equal to 5 N. row ^"1 and / or 5 N. column ^{" 1} , preferably 10 N. row ^"1 and / or 10 N. column ^{" 1} and more preferably N row ^"1 and / or 30 N. column ^{" 1} , the maximum force being measured according to ISO 13934-1: 2013 applied to the or each knit embedded in the standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971.

[027] - The or each knit has a maximum force less than or equal to

70 N. row ^"1 and / or 70 N. column ^{" 1} , preferably 60 N. row ^"1 and / or 60 N. column ^{" 1} , the maximum force being measured according to ISO 13934-1: 2013 applied to the or each knit embedded in the standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971.

[028] Preferably, the transverse general direction of the or each knit is substantially parallel to the circumferential direction of the tire.

[029] Preferably, the main general direction of the or each knit is substantially parallel to the radial direction of the tire.

[030] In a preferred embodiment, the main directions of the knit or knits of each layer are substantially parallel to each other. In another preferred embodiment, the transverse directions of the knit or knits of each layer are substantially parallel to each other. Alternatively, the main directions of the knit or knits of each layer form a substantially non-zero angle two by two, preferably are substantially perpendicular two by two. Alternatively, the transverse directions of the knit or knits of each layer form a substantially non-zero angle two by two, preferably are substantially perpendicular two by two.

[031] According to other preferred features of the tire:

[032] - The force at 100% elongation of the or each knit in the main direction and the transverse direction is greater than or equal to 0.5 N. row ^"1 and 0.5 N. column ^{" 1} , preferably N. row ^"1 and 5 N. column ^{" 1} and more preferably 15 N. row ^"1 and 15 N. column ^{" 1} , the force at 100% elongation being determined from a force-elongation curve obtained applying the ISO 13934-1: 2013 standard to the or each knit embedded in the standard elastomer matrix and the number of rows and columns being measured according to standard NF EN 14971.

[033] - The force at 100% elongation of the or each knit in the main direction and the transverse direction is less than or equal to 40 N. row ^"1 and 40 N. column ^{" 1} , preferably 35 N. row ^"1 and 35 N. column ^{" 1} , 100% strength of elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the standard elastomer matrix and the number of rows and columns being measured according to the standard NF EN 14971.

[034] According to other preferred features of the tire:

[035] - The force at 50% elongation of the or each knit in the main direction and the transverse direction, is greater than or equal to 0.5 N. row ^"1 and 0.5 N. column ^{" 1} , of preferably 2.5 N. row ^"1 and 2.5 N. column ^{" 1} and more preferably 10 N. row ^"1 and 10 N. column ^{" 1} , the force at 50% elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the standard elastomer matrix and the number of rows and columns being measured according to standard NF EN 14971.

[036] - The force at 50% elongation of the or each knit in the main direction and the transverse direction is less than or equal to 25 N. row ^"1 and 10 N. column ^{" 1} , preferably 20 N. row ¹ and 20 N. column ^"1 , the force at 50% elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the matrix of standard elastomer and the number of rows and columns being measured according to standard NF EN 14971.

[037] According to other preferred features of the tire:

[038] - The force at 10% elongation of the or each knit in the main direction and the transverse direction, is greater than or equal to 0.05 N. row ^"1 and 0.05 N. column ^{" 1} , of preferably 1 N. row ^"1 and 1 N. column ^{" 1} and more preferably 2 N. row ^"1 and 2 N. column ^{" 1} , the force at 10% elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the standard elastomer matrix and the number of rows and columns being measured according to standard NF EN 14971.

[039] - The force at 10% elongation of the or each knit in the main direction and the transverse direction is less than or equal to 9 N. row ^"1 and 9 N. column ^{" 1} , preferably 7 N. row ¹ and 7 N. Column ^"1 , the force at 10% elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the matrix of standard elastomer and the number of rows and columns being measured according to standard NF EN 14971.

[040] According to other preferred features of the tire: [041] - The maximum force of the or each knit in the main direction and the transverse direction is greater than or equal to 5 N. row ^"1 and 5 N. column ^{" 1} , preferably 10 N. row ^"1 and 10 N column ^1, more preferably N, row ¹ and N, column ¹ , the maximum force being measured according to ISO 13934-1: 2013 applied to the or each knit embedded in the standard elastomer matrix; number of rows and columns being measured according to standard NF EN 14971.

[042] - The maximum force of the or each knit in the main direction and the transverse direction is less than or equal to 70 N. row ^"1 and 70 N. column ^{" 1} , preferably 60 N. row ^"1 and 60 N column ^"1 , the maximum force being measured according to ISO 13934-1: 2013 applied to the or each knit embedded in the standard elastomer matrix and the number of rows and columns being measured according to standard NF EN 14971.

[043] According to other preferred features of the tire:

[044] - The or each knit has, according to the main general direction and / or the transverse general direction, a force at 100% elongation greater than or equal to 50 N, preferably 200 N and more preferably 500 N, the force at 100% elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the standard elastomer matrix.

[045] - The or each knit has, according to the main general direction and / or the transverse general direction, a force at 100% elongation less than or equal to 1500 N, preferably 1400 N and more preferably 1300 N, the force at 100% elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the standard elastomer matrix.

[046] According to other preferred features of the tire:

[047] - The or each knit has, according to the main general direction and / or the transverse general direction, a force at 50% elongation greater than or equal to 50 N, preferably 250 N, the force at 50% of elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the standard elastomer matrix.

[048] - The or each knit has, according to the main general direction and / or the transverse general direction, a force at 50% elongation less than or equal to 1000 N, preferably 700 N, the force at 50% of elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the standard elastomer matrix. [049] According to other optional characteristics of the tire:

[050] - The or each knit has, according to the main general direction and / or the transverse general direction, a force at 10% elongation greater than or equal to 5 N, preferably 50 N, the force at 10% of elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the standard elastomer matrix.

[051] - The or each knit has, according to the main general direction and / or the transverse general direction, a force at 10% of elongation less than or equal to 700 N, preferably 600 N, the force at 10% of elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the standard elastomer matrix.

[052] According to other preferred features of the tire:

[053] - The or each knit has, according to the main general direction and / or the transverse general direction, a maximum force greater than or equal to 600 N, the maximum force being measured according to ISO 13934-1: 2013 applied to the to each knit embedded in the standard elastomer matrix.

[054] - The or each knit has, according to the main general direction and / or the transverse general direction, a maximum force less than or equal to 2200 N, the maximum force being measured according to ISO 13934-1: 2013 applied to the to each knit embedded in the standard elastomer matrix.

[055] According to other preferred features of the tire:

[056] - The or each knit has, according to the main general direction and / or the transverse general direction, an elongation at break greater than or equal to 30%, preferably 100%, the elongation at break being measured according to the ISO 13934-1: 2013 standard applied to the or each knit embedded in the standard elastomer matrix. Such elongation at break is much greater than a conventional fabric whose elongation at break is of the order of 10% to 15% in the direction of the son. Such elongation allows the assembly to deform sufficiently even during extreme cornering stresses.

[057] - The or each knit has, according to the main general direction and / or the transverse general direction, an elongation at break less than or equal to 1200%, preferably 250%, the elongation at break being measured according to the ISO 13934-1: 2013 standard applied to the or each knit embedded in the standard elastomer matrix.

[058] Advantageously, the characteristics described above (100% strength, 50% and 10% elongation, maximum force and elongation at break) are observable. according to the main senior management and / or transversal management. In a variant, they are observable only in the main general direction. In another variant, they are observable only in the transverse general direction. Finally, in a last variant, they are observable according to the main general direction and the transverse general direction.

[059] According to other preferred features of the tire:

the force at 100% elongation of the or each knit in the main direction, determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the matrix of standard elastomer, is greater than or equal to 150 N, preferably 700 N and more preferably 1000 N, and

the force at 100% elongation of the or each knit in the transverse direction, determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the matrix of standard elastomer, is greater than or equal to 50 N, preferably 500 N.

[060] According to other preferred features of the tire:

the force at 50% elongation of the or each knit along the main direction, determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the matrix of standard elastomer is greater than or equal to 120 N, preferably 500 N, and

the force at 50% elongation of the or each knit in the transverse direction, determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the matrix of standard elastomer, is greater than or equal to 50 N, preferably 300 N.

[061] According to other preferred features of the tire:

the force at 10% elongation of the or each knit in the main direction, determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the matrix of standard elastomer is greater than or equal to 30 N, preferably 170 N, and

the force at 10% elongation of the or each knit in the transverse direction, determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit embedded in the matrix of standard elastomer, is greater than or equal to 10 N, preferably 80 N. [062] According to other preferred features of the tire:

the elongation at break of the or each knit according to the main direction measured according to the ISO 13934-1: 2013 standard applied to the or each knit embedded in the standard elastomer matrix is less than or equal to 700%, preferably 250%, and the elongation at break of the or each knit according to the transverse direction measured according to ISO 13934-1: 2013 applied to the or each knit embedded in the standard elastomer matrix is less than or equal to 1200 %, preferably 250%.

[063] According to other preferred features of the tire:

the elongation at break of the or each knit according to the principal direction measured according to the ISO 13934-1: 2013 standard applied to the or each knit embedded in the standard elastomer matrix is greater than or equal to 150%, and

the elongation at break of each knit according to the transverse direction measured according to the ISO 13934-1: 2013 standard applied to the or each knit embedded in the standard elastomer matrix is greater than or equal to 150%.

[064] According to other preferred features of the tire:

the maximum force of the or each knit according to the main direction measured according to ISO 13934-1: 2013 applied to the or each knit embedded in the standard elastomer matrix is greater than or equal to 600 N, and

the maximum force of the or each knit according to the transverse direction measured according to ISO 13934-1: 2013 applied to the or each knit embedded in the standard elastomer matrix is greater than or equal to 600 N.

[065] According to other preferred features of the tire:

the maximum force of the or each knit according to the main direction measured according to ISO 13934-1: 2013 applied to the or each knit embedded in the standard elastomer matrix is less than or equal to 2200 N, and

the maximum force of the or each knit according to the transverse direction measured according to ISO 13934-1: 2013 applied to the or each knit embedded in the standard elastomer matrix is less than or equal to 1500 N.

[066] Advantageously, the main and transverse directions of the or each knit, are relative to each other, an angle between 75 ° and 105 °, preferably between 85 ° and 95 °.

[067] In one embodiment, the surface density of the mesh or each knit, measured according to standard NF EN 14971, is less than or equal to 700 meshes. cm ² , preferably 100 mesh cm ² and more preferably 75 mesh. cm ^"2 . [068] In one embodiment, the surface density of the mesh or each knit, measured according to the standard NF EN 14971, is greater than or equal to 15 meshes. cm ^{^"2,} preferably at 25 mesh. ^{cm" 2} and more preferably at 30 mesh. cm ^"2 .

[069] Preferably, the or each knit consists of one or more filamentary elements of a material chosen from a polyester, a polyamide, a polyketone, a polyvinyl alcohol, a cellulose, a mineral fiber, a natural fiber, an elastomeric material or a mixture of these materials.

[070] Among the polyesters, mention will be made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), polypropylene terephthalate (PPT) or polypropylene naphthalate (PPN) . Among the polyamides, mention may be made of an aliphatic polyamide such as nylon or an aromatic polyamide such as aramid. Among the polyvinyl alcohols, mention may be made of Kuralon®. Among the celluloses, mention will be made of rayon. Among the mineral fibers, mention will be made of glass and carbon fibers. Among the natural fibers, mention may be made of hemp or flax fibers. Elastomeric materials include Lycra ®.

[071] Advantageously, the or each wire element comprises at least one multifilament strand comprising several elementary monofilaments.

[072] In a variant in which the or each knit comprises a plurality of multifilament strands, all the multifilament strands are made of the same material. In another variant in which the or each knit comprises a plurality of multifilament strands, the multifilament strands are made in at least two different materials.

[073] In one embodiment, each wire element comprises a single multifilament strand called surtors comprising several elementary monofilaments.

[074] In another embodiment, each wire element comprises a plurality of multifilament strands, each called surtors, each comprising a plurality of elementary monofilaments and assembled together in a helix to form a twist.

[075] Preferably, each wire element has a tenacity greater than or equal to 30 cN.dtex- ¹ . For example, PET wire elements have a value of about 70 cN.dtex- ¹ and aramid wire elements. have a tenacity of the order of 200 cN.dtex ^-1 .

[076] Advantageously, each multifilament strand comprises between 2 and 2000 elementary monofilaments, preferably between 50 and 1000 elementary monofilaments. [077] Advantageously, the diameter of each elemental monofilament ranges from 10 μηη to 100 μηι, preferably from 10 μηη to 50 μηη and more preferably from 12 μηη to 30 μηη. Such a diameter makes it possible to obtain a relatively flexible knit and thus compatible with its use in a tire.

[078] In another embodiment, each wire element comprises, preferably consists of, a single monofilament.

[079] Preferably, the or each knit is coated with a layer of adhesion adhesive. The adhesive used is for example of the RFL type (Resorcinol-Formaldehyde-Latex) or for example, as described in the publications WO2013017421, WO2013017422, WO2013017423.

[080] In the tire, the or each knit is preferably embedded in an elastomer matrix. By elastomer matrix (or rubber, the two terms being synonymous) is meant a matrix comprising at least one elastomer.

[081] Preferably, the elastomer is a diene elastomer. In known manner, the diene elastomers can be classified in two categories: "essentially unsaturated" or "essentially saturated". The term "essentially unsaturated" means a diene elastomer derived at least in part from conjugated diene monomers having a level of units or units of diene origin (conjugated dienes) which is greater than 15% (mol%); Thus, diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins of the EPDM type do not fall within the above definition and may in particular be described as "essentially saturated" diene elastomers ( low or very low diene origin, always less than 15%). In the category of "essentially unsaturated" diene elastomers, the term "highly unsaturated" diene elastomer is particularly understood to mean a diene elastomer having a content of units of diene origin (conjugated dienes) which is greater than 50%.

[082] Although it is applicable to any type of diene elastomer, the present invention is preferably implemented with a diene elastomer of the highly unsaturated type.

[083] This diene elastomer is more preferably chosen from the group consisting of polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), various butadiene copolymers, the various isoprene copolymers, and mixtures of these elastomers, such copolymers being chosen in particular from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR) and copolymers of isoprene-butadiene-styrene (SBIR). [084] A particularly preferred embodiment consists in using an "isoprene" elastomer, that is to say a homopolymer or a copolymer of isoprene, in other words a diene elastomer chosen from the group consisting of rubber natural (NR), synthetic polyisoprenes (IR), different isoprene copolymers and mixtures of these elastomers. The isoprene elastomer is preferably natural rubber or synthetic polyisoprene of the cis-1,4 type. Among these synthetic polyisoprenes, polyisoprenes having a level (mol%) of cis-1,4 bonds greater than 90%, more preferably still greater than 98%, are preferably used. According to a preferred embodiment, each layer of rubber composition comprises 50 to 100 phr of natural rubber. According to other preferred embodiments, the diene elastomer may consist, in whole or in part, of another diene elastomer such as, for example, an SBR elastomer used in or with another elastomer, for example type BR.

[085] The elastomer matrix may contain one or more elastomer (s) diene (s), which (s) last (s) can be used in combination with any type of synthetic elastomer other than diene, even with polymers other than elastomers. The rubber composition may also comprise all or part of the additives normally used in rubber matrices intended for the manufacture of tires, such as, for example, reinforcing fillers such as carbon black or silica, coupling agents, anti-aging agents. antioxidants, plasticizers or extension oils, whether the latter are of aromatic or non-aromatic nature (in particular very weak or non-aromatic oils, for example of the naphthenic or paraffinic type, with high or preferably low viscosity, MES or TDAE oils), plasticizing resins with a high Tg greater than 300 ° C, agents facilitating the implementation (processability) of the compositions in the green state, tackifying resins, anti-reversion agents, methylene acceptors and donors such as, for example, HMT (hexamethylenetetramine) or H3M (hexamethoxymethylmelamine), resins forcing (such as resorcinol or bismaleimide), known adhesion promoter systems such as metal salts for example, in particular salts of cobalt, nickel or lanthanide, a crosslinking or vulcanization system.

[086] Preferably, the elastomer matrix crosslinking system is a so-called vulcanization system, that is to say based on sulfur (or a sulfur donor) and a primary accelerator vulcanization. To this basic vulcanization system may be added various secondary accelerators or activators of vulcanization known. The sulfur is used at a preferential rate of between 0.5 and 10 phr, the primary vulcanization accelerator, for example a sulfenamide, is used at a preferential rate of between 0.5 and 10 phr. The level of reinforcing filler, for example carbon black or silica, is preferably greater than 50 phr, especially between 50 and 150 phr.

[087] Suitable carbon blacks are all carbon blacks, especially blacks of the HAF, ISAF, SAF type conventionally used in tires (so-called pneumatic grade blacks). Among the latter, mention will be made more particularly of carbon blacks of (ASTM) grade 300, 600 or 700 (for example N326, N330, N347, N375, N683, N772). Suitable silicas are in particular precipitated or pyrogenic silicas having a BET surface area of less than 450 m ² / g, preferably from 30 to 400 m ² / g.

[088] One skilled in the art will, in the light of the present description, adjust the formulation of the rubber composition to achieve the desired properties (including modulus of elasticity), and adapt the formulation to the specific application envisaged.

[089] Preferably, the elastomer matrix has, in the crosslinked state, a secant modulus in extension, at 10% elongation, which is between 4 and 80 MPa, more preferably between 4 and 20 MPa. The modulus measurements are carried out in tension, unless otherwise indicated, according to ASTM D 412 of 1998 (specimen "C"). The secant modulus is measured in second elongation (that is to say after an accommodation cycle). "true" (that is to say, brought back to the actual section of the test piece) at 10% elongation, noted here Ms and expressed in MPa (normal temperature and humidity conditions according to ASTM D 1349 of 1999).

[090] In one embodiment, the tire is for industrial vehicles chosen from light trucks, heavy vehicles such as "heavy goods vehicles" - the., Subway, bus, road transport equipment (trucks, tractors, trailers), vehicles off-the-road -, agricultural or engineering machinery, aircraft, other transport or handling vehicles. In another embodiment, the tire is for passenger vehicle. In yet another embodiment, the tire is for a two-wheeled vehicle.

[091] Preferably, the assembly consists of several knits, each knit forming at least one layer of the assembly. Preferably, the knits of the assembly are identical. However, it will also be possible to consider using different knits in the assembly. Alternatively, the assembly comprises a single knit wound on several layers. [092] Advantageously, the layers are partially superimposed in a radial and / or axial direction of the tire. Thus, when the assembly is arranged in the top of the tire, the layers are preferably partially superposed in a radial direction of the tire. When the assembly is arranged in the sidewall of the tire, the layers are preferably partially superposed in an axial direction of the tire.

[093] In a preferred embodiment, the tire comprises a carcass reinforcement anchored in two beads and radially surmounted by a crown reinforcement itself surmounted by a tread which is joined to the beads by two flanks, each flank comprising the assembly.

[094] By positioning the assembly in the sidewall, the drift rigidity of the tire is improved.

[095] In a preferred embodiment, the radially outer end of the assembly is axially inner with respect to the axially outer end of the crown ply radially adjacent to the assembly.

[096] In an even more preferred embodiment, the axial distance between the radially outer end of the assembly and the axially outer end of a crown ply radially adjacent to the assembly is greater than or equal to 5 mm. preferably at 10 mm and more preferably at 15 mm.

[097] In a preferred embodiment, the radially outer end of the assembly is radially interposed between the carcass reinforcement and the crown reinforcement. Alternatively, the radially outer end of the assembly is radially outer relative to the crown reinforcement.

[098] In some embodiments, the carcass reinforcement is anchored in each bead by a flipping around an annular bead structure so as to form a forward strand and a return strand.

[099] In a particularly preferred embodiment, the radial distance between the radially inner end of the assembly and the radially median plane of the annular structure of the bead is less than or equal to 15 mm, preferably to 10 mm and more. preferably at 5 mm. Thus, in the case of a nip of the flank against the rim, the assembly can prevent degradation of the carcass reinforcement. The radially median plane is the plane separating the annular structure into two parts having an equal space in the radial direction.

In a first variant, the assembly extends in the bead axially between the forward strand and the back strand of the carcass reinforcement. In a second variant, the assembly extends in the bead axially outside the return strand.

In other embodiments, the assembly is arranged axially inside the carcass reinforcement.

In a preferred embodiment, the assembly forms a monolithic ring having an axis of revolution substantially parallel to the axis of the tire.

By monolithic ring means that each mesh of the or each knit is assembled with at least one other mesh of the same knit. Thus, in a monolithic ring, there is no overlap between two ends of the same knit. Such a ring simplifies the manufacturing process of the tire.

The invention also relates to the use of at least one assembly of at least two layers of at least one knit, the two layers being at least partially superimposed on one another, as that reinforcing element of a tire.

Another object of the invention is a method of manufacturing a tire as defined above, in which the assembly is embedded in at least one elastomer matrix.

In one embodiment, each layer of knit is embedded separately in an elastomer matrix in order to form several layers. The elastomer matrices may be identical or different. Then, the webs thus formed are at least partially superimposed in order to form the assembly.

In another embodiment, the knit layers are at least partially superimposed so as to form the assembly. Then, the assembly thus formed is drowned in an elastomer matrix.

In yet another embodiment, a first layer of the elastomer matrix is positioned, then a first layer of knit is positioned on the first layer of the elastomer matrix, and then a second layer of the elastomer is positioned. elastomer matrix on the first knit layer, then a second knit layer is positioned on the second layer of the elastomer matrix and finally a third layer of the elastomer matrix is positioned on the second knit layer.

The invention will be better understood on reading the description which follows, given solely by way of nonlimiting example and with reference to the drawings in which: Figure 1 is a sectional view of a tire according to a first embodiment of the invention comprising an assembly;

- Figure 2 is a schematic view of the developed tire of Figure 1 illustrating the axial distribution of the assemblies;

FIG. 3 is a schematic view of the tire assembly of FIG. 1;

Figure 4 is a detail view of one of the knits of the assembly of Figure 3; Figures 5 and 6 are graphs illustrating force-elongation curves of the knits of Figures 1 to 4 and a control knit;

FIGS. 7 and 8 are views similar respectively to those of FIGS.

1, 2 of a tire according to a second embodiment;

Figures 9 and 10 are views respectively similar to those of Figures 1, 2 of a tire according to a third embodiment;

Figures 11 and 12 are views respectively similar to those of Figures 1, 2 of a tire according to a fourth embodiment;

Figures 13 and 14 are views respectively similar to those of Figures 1, 2 of a tire according to a fifth embodiment, and Figures 15 and 16 are views respectively similar to those of Figures 1, 2 of a tire according to a sixth embodiment.

In the following description, in the use of the term "radial", it is appropriate to distinguish several different uses of the word by the person skilled in the art. First, the term refers to a radius of the tire. It is in this sense that we say from point A that it is "radially interior" to a point B (or "radially inside" of point B) if it is closer to the axis of rotation of the tire than the point B. Conversely, a point C is said to be "radially outside a point D (or" radially outside "of the point D) if it is farther from the axis of rotation of the only point D. It will be said that one is advancing "radially inwards (or outward)" when moving towards smaller (or larger) radii. When it comes to radial distances, this sense of the term also applies.

In contrast, a reinforcing element or a reinforcement is said to be "radial" when the reinforcing element or the reinforcing elements of the reinforcement make with the circumferential direction an angle greater than or equal to 65 ° and less than or equal to at 90 °.

An "axial" direction is a direction parallel to the axis of rotation of the tire. A point E is said to be "axially inner" at a point F (or "axially inside" of the point F) if it is closer to the median plane of the tire than the point F. Conversely, a point G is said to be "axially outside at" a point H (or "axially outside" of the point H) if it is farther from the median plane of the tire than the point H.

The "median plane" M of the tire is the plane which is normal to the axis of rotation of the tire and which is equidistant from the annular reinforcing structures of each bead.

A "circumferential" direction is a direction that is perpendicular to both a radius of the tire and the axial direction.

On the other hand, any range of values designated by the expression "between a and b" represents the range of values from more than a to less than b (that is, terminals a and b excluded). ) while any range of values designated by the expression "from a to b" means the range of values from the terminal "a" to the terminal "b" that is to say including the strict limits " a "and" b ". EXAMPLES OF PNEUMATIC TIRES ACCORDING TO THE INVENTION

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

FIGS. 1 and 2 show a tire according to a first embodiment of the invention and designated by the general reference 10. The tire 10 is substantially of revolution about the axis X. The tire 10 is here intended for a passenger vehicle.

The tire 10 comprises an apex 12 comprising a crown reinforcement 14 comprising a working reinforcement 15 comprising two working plies 16, 18 of reinforcing elements and a reinforcement 17 of protection or shrinking comprising a protective ply 19 The crown reinforcement 14 is surmounted by a tread 20. Here, the protective reinforcement 17, here the protective ply 19, is inserted radially between the working reinforcement 15 and the tread 20.

Two flanks 22 extend the vertex 12 radially inwardly. The tire 10 further comprises two beads 24 radially inner to the flanks 22 and each having an annular reinforcement structure 26, in this case a bead wire 28, surmounted by a mass of tamping rubber 30, and a carcass reinforcement. radial 32. The carcass reinforcement 32 is surmounted radially by the crown reinforcement 14. The carcass reinforcement 32 preferably comprises a single carcass ply 34 of radial textile reinforcing elements, the ply 34 being anchored to each of the beads 24 by a reversal around the bead wire 28 so as to form in each a bead 24 a strand 38 extending from the beads 24 through the sidewalls 22 to the top 12, and a return strand 40, the radially outer end of the return strand 40 being here substantially halfway up the tire 10. The carcass reinforcement 32 thus extends from the beads 24 through the flanks 22 to the top 12. Alternatively, the radial reinforcing elements are metallic. The tire 10 also comprises an inner sealing ply 42, generally made of butyl, arranged axially and radially inside the carcass reinforcement 32.

The working plies 16, 18 comprise metal reinforcing elements or conventional textiles for the skilled person and forming an angle ranging from 15 ° and 40 °, preferably from 20 ° to 30 ° and here equal to 26 ° with the circumferential direction Z of the tire. The reinforcement elements of the working plies are crossed by one working ply with respect to the other.

The protective ply 19 comprises metal or textile reinforcing elements also conventional for the skilled person forming an angle ranging from 0 ° to 10 ° with the circumferential direction Z of the tire.

In addition, the tire comprises an additional reinforcement 41 comprising at least one additional ply 43. In the example of FIG. 1, the additional reinforcement 41 comprises an additional ply 43 comprising an assembly 45 of at least two layers. at least one knit, the two layers being at least partially superimposed on one another. In this case, the assembly 45 comprises two knits 44-i, 44 ₂ , each knit forming a layer. Alternatively, one could imagine a single knit wound on two turns around the axis of the tire 10, each turn forming a layer of the assembly 45.

As a variant, the additional reinforcement 41 comprises two additional plies 43, each additional ply then comprising a knit 44-i, 44 ₂ . In both cases, the assembly 45 of knits 44-i, 44 ₂ is arranged axially outside the carcass reinforcement 34. Thus, as illustrated in FIG. 1, each flank 22 comprises an assembly 45 of knits. 44-i, 44 ₂ .

The radially outer end P1 of the assembly 45 is axially inner with respect to the axially outer end P3 of the crown ply 18 radially adjacent to the assembly 45. In addition, the radially outer end P1 of the assembly 45 is radially interposed between the carcass reinforcement 32 and the crown reinforcement 14.

The axial distance d1 between the radially outer end P1 of the assembly 45 and the axially outer end P3 of the crown ply 18 radially adjacent to the assembly 45 is greater than or equal to 5 mm, preferably greater than or equal to 5 mm. 10 mm. Here, d 1 = 10 mm. In other embodiments, d1 is greater than or equal to 15 mm.

The assembly 45 extends, in the bead, axially between the forward strand 38 and the back strand 40 of the carcass reinforcement 32. Alternatively, an embodiment may be envisaged in which the assembly 45 extends, in the bead, axially outside the return strand 40.

The radial distance d2 between the radially inner end P2 of the assembly 45 and the radially median plane P4 of the annular structure 26 of the bead 24 is less than or equal to 15 mm, preferably to 10 mm and more preferably to 5 mm. Here d2 = 5 mm.

Each working ply 16, 18, protection 19, carcass 34 and additional 43 comprises an elastomer matrix in which are embedded the reinforcing elements of the corresponding ply. The compositions of the elastomer matrices of the working plies 16, 18, protection 19, carcass 34 and additional plies 43 are conventional compositions for calendering reinforcing elements conventionally comprising a diene elastomer, for example natural rubber, a reinforcing filler, for example carbon black and / or silica, a crosslinking system, for example a vulcanization system, preferably comprising sulfur, stearic acid and zinc oxide, and optionally an accelerator and / or a vulcanization retarder and / or various additives.

FIG. 3 shows the assembly 45. In the present case, the two knits 44-I, 44 ₂ are identical and have the same dimensions so that they are entirely superimposed on each other. other in a radial and / or axial direction of the tire 10, here in the axial direction X of the tire 10. It may, however, be envisaged knits 44-i, 44 ₂ of different types and / or different dimensions.

As shown in FIG. 4, each knit 44 ^ 44 ₂ comprises columns C1, C2, C3, C4 of loops B as well as rows R1, R2, R3, R4 of loops B. The loops B of a same column Ci are arranged one after the other substantially in a general direction called main X1. Loops B of the same row Ri are arranged next to each other substantially in a generally transverse direction Z1. The main directions X1 and transverse Z1 of each knit 44-i, 44 ₂ are, relative to each other, an angle between 75 ° and 105 °, preferably between 85 ° and 95 °. Here, the main directions X1 and transverse Z1 are substantially perpendicular to each other.

The transverse general direction Z1 makes an angle at most equal to 10 ° with the circumferential direction Z of the tire 10 and here an angle equal to 0 °, the transverse general direction Z1 of each knit 44-i, 44 ₂ being substantially parallel to the circumferential direction Z of the tire. The main general direction X1 of the knit 44 is substantially parallel to the radial direction X of the tire.

Each knit 44 ^ 44 ₂ has a jersey type texture and was custom made from a conventional knitting process for the skilled person of this field. Each knit 44-i, 44 ₂ has, in the direction Y1 a thickness ranging from 0.3 to 3 mm, preferably 0.8 to 1, 7 mm and here equal to 0.8 mm.

The areal density of knit stitches, measured according to standard NF EN 14971, is less than or equal to 700 meshes. cm ² , preferably 100 mesh cm ² and more preferably 75 mesh. cm ^"2. The areal density of the knitted fabric is greater than or equal to 15 meshes. ^{cm" 2,} preferably at 25 mesh. cm ² and more preferably 30 mesh cm ² . In this case, the surface density is equal to 55 meshes. cm ² .

FIGS. 5 and 6 show force-elongation curves obtained by applying the ISO 13934-1: 2013 standard to each knit 44-i, 44 ₂ embedded in a standard elastomer matrix as defined above. In this example, the standard elastomer matrix comprises a diene elastomer, a reinforcing filler, for example carbon black, a vulcanization system and the usual additives used by those skilled in the art. The compositions of these standard matrices are within the abilities of a person skilled in the art who will be able to formulate them to obtain the apparent MA100 module at 100% desired elongation, here 1.6 MPa ± 0.2 MPa (ASTM D412-1998, test piece "C"). On the other hand, the apparent MA10 modulus at 10% elongation of the standard elastomer matrix used here is equal to 3.3 MPa ± 0.5 MPa and the MA300 apparent modulus at 300% elongation of the matrix of The standard elastomer used here is equal to 1.7 MPa ± 0.3 MPa (ASTM D412-1998, "C" test piece).

The curves I (main direction) and II (transverse direction) correspond to each knit 44-i, 44 ₂ described above. The curves III (main direction) and IV (transverse direction) correspond to a control knit used alone in the tire Q1 of the comparative tests below. As can be seen in FIGS. 5 and 6, each knit 44 ^ 44 ₂ has particular properties of elongation at break and maximum force measured according to ISO 13934-1: 2013, as well as properties force at 10%, 50% and 100% elongation determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard. The number of rows and / or columns is measured according to standard NF EN 14971.

Each knit 44-i, 44 ₂ has, according to the main general direction X1 and / or the transverse general direction Z1, and here in the two directions X1 and Z1, a force at 100% elongation greater than or equal to 50 N, preferably 200 N and more preferably 500 N and less than or equal to 1500 N, preferably 1400 N and more preferably 1300 N. During strong cornering, the assembly 45 is highly stressed. It has been observed that, during strong cornering stresses, the elongation of the knits in the circumferential direction of the tire 10 is of the order of 100% in the circumferential direction of the tire 10. Thus, during these strong stresses, in order to To obtain a high rigidity of drift, it is desirable that the force of the assembly is relatively high, as it is the case for the knits of curves I and II. Preferably, the force at 100% elongation in the main direction X1 is greater than or equal to 150 N, preferably 700 N and more preferably 1000 N and the force at 100% elongation in the transverse direction Z1 is greater than or equal to at 50 N, preferably 500 N. Even more preferably, on the one hand, each knit 44-i, 44 ₂ has a force at 100% elongation greater than or equal to 0.5 N. row ^"1 and / or 0.5 N. column ^"1 , preferably 5 N. row ^{" 1} and / or 5 N. column ^"1 , and more preferably 15 N. row ^{" 1} and / or 15 N. column ^"1 according to the main direction and / or transverse.

On the other hand, according to the invention, each knit 44-i, 44 ₂ has a force at 100% elongation less than or equal to 40 N. row ^"1 and / or 40 N. column ^{" 1} according to the main and / or transverse direction. Preferably, the force at 100% elongation is less than or equal to 35 N. row ^"1 and / or 35 N. column ^{" 1} in the main direction and / or transverse.

Preferably, each knit 44 ^ 44 ₂ has, in the main general direction X1 and / or the transverse general direction Z1, a force at 50% elongation greater than or equal to 50 N, preferably 250 N, and less than or equal to 1000 N, preferably 700 N. More preferably, on the one hand, each knit 44-i, 44 ₂ has a force at 50% elongation greater than or equal to 0.5 N. row ^"1 and / or 0.5 N. column ^"1 , preferably 2.5 N. row ^{" 1} and / or 2.5 N. column ^"1 and more preferably 10 N. row ^{" 1} and / or 10 N. column ^"1 according to the main direction and / or transverse. On the other hand, each knit 44 ^ 44 ₂ has a force at 50% elongation less than or equal to 25 N. row ^"1 and / or 25 N. column ^{" 1} , preferably 20 N. row ^"1 and / or N. column ¹ in the main and / or transverse direction.

Preferably, each knit 44-i, 44 ₂ has, according to the main general direction X1 and / or the transverse general direction Z1, a force at 10% elongation greater than or equal to 5 N, preferably 50 N and less than or equal to 700 N, preferably 600 N. More preferably, on the one hand, each knit 44-i, 44 ₂ has a force at 10% elongation greater than or equal to 0.05 N. row ^{" 1} and / or 0.05 N. column ^"1 , preferably 1 N. row ^{" 1} and / or 1 N. column ^"1 and more preferably 2 N. row ^{" 1} and / or 2 N. column ^"1 according to the main and / or transverse direction. On the other hand, each knit 44 ^ 44 ₂ has a force at 10% elongation less than or equal to 9 N. row ^"1 and / or 9 N. column ^{" 1} , preferably 7 N. row ^"1 and / or 7 N. column ^"1 according to the main and / or transverse direction.

Preferably, the force at 50% elongation in the main direction X1 is greater than or equal to 120 N, preferably 500 N and the force at 50% elongation in the transverse direction Z1 is greater than or equal to 50 N, preferably 300 N. Preferably, the force at 10% elongation in the main direction X1 is greater than or equal to 30 N, preferably 170 N and the force at 10% elongation in the transverse direction Z1 is greater or equal to 10 N, preferably 80 N.

Preferably, each knit 44 ^ 44 ₂ has, according to the main general direction X1 and / or the transverse general direction Z1, a maximum force greater than or equal to 600 N and less than or equal to 2200 N. Each knit 44- i, 44 ₂ corresponding to curves I and II individually has a moderate strength and lower than the knit corresponding to curves III and IV. The assembly, on the other hand, has a relatively high mechanical strength and greater than that of the single knit corresponding to curves III and IV. This feature is particularly advantageous in the case of shocks between the tire and possible obstacles, known by the English name "road hazard". Preferably, the maximum force in the main direction X1 is greater than or equal to 600 N and the maximum force in the transverse direction Z1 is greater than or equal to 600 N. Preferably, the maximum force in the main direction X1 is less than or equal to 2200. N, and the maximum force in the transverse direction Z1 is less than or equal to 1500 N. More preferably, on the one hand, each knit 44i, 44 ₂ has a maximum force greater than or equal to 5 N. row ^" ¹ and / or N. column ^"1 , preferably 10 N. row ^{" 1} and / or 10 N. column ^"1 and above preferably N row ^"1 and / or 30 N. column ^{" 1} in the main direction and / or transverse. On the other hand, each knit 44-i, 44 ₂ has a maximum force less than or equal to 70 N. row ^"1 and / or 70 N. column ^{" 1} , preferably 60 N. row ^"1 and / or 60 N column ^"1 according to the main and / or transverse direction.

Preferably, each knit 44 ^ 44 ₂ has, according to the main general direction X1 and / or the transverse general direction Z1, an elongation at break of greater than or equal to 30%, preferably 100% and less than or equal to 1200%, preferably 250%. By limiting the elongation at break of each knit 44-i, 44 ₂ corresponding to the curves I and II, it is ensured that the knit will not deform unnecessarily, the elastomer matrix adjacent to the risking assembly, in all cases, to break before knitting. Preferably, the elongation at break in the main direction X1 is less than or equal to 700%, preferably 250% and the elongation at break in the transverse direction Z1 is less than or equal to 1200%, preferably 250%. Preferably, the elongation at break in the main direction X1 is greater than or equal to 150% and the elongation at break in the transverse direction Z1 is greater than or equal to 150%.

Each knit 44-i, 44 ₂ consists of one or more wire elements E of a material chosen from a polyester, a polyamide, a polyketone, a cellulose, a mineral fiber, a natural fiber, a material elastomer or a mixture of these materials.

The or each wire element E comprises at least one multifilament strand comprising a plurality of elementary monofilaments. In the present case, the or each wire element E comprises two strands of nylon each of 47 tex overworked each at 250 revolutions. m ^"1 in a first direction and then twisted around each other at 250 revolutions m ^{" 1} in a second direction opposite to the first direction.

We will now describe a method of manufacturing the tire 10 as described above. Only the main steps relating to the invention will be described, the other steps being easily achievable from the general knowledge of those skilled in the art.

During the process, a blank is formed comprising the beads 24, the flanks 22 and the carcass reinforcement 32, here the carcass ply 34.

In a first embodiment of the process, each knit 44-i, 44 _{2 is} knitted individually or collectively in an elastomer matrix so as to obtain one or two additional plies 43, for example by individual calendering of each knitted fabric. 44-1, 44 ₂ or by collective calendering of knits 44 _! , 44 ₂ between two bands of elastomer matrices. Then, this or these additional plies 43 are reported on the previously formed blank. Then, the crown reinforcement 14 and the tread 20 are reported.

In a second embodiment, a first band of the elastomer matrix is reported on the blank. Then, the assembly 45 of knits 44-i, 44 _{2 is reported} on the first strip of the elastomer matrix. Then, a second strip of the elastomer matrix is reported on the assembly 45 of knits 44-i, 44 ₂ . Finally, the crown reinforcement 14 and the tread 20 are reported. During the baking of the blank to form the tire 10, the elastomer matrix of the first and second strips flows through the assembly 45 of the knitwear 44-i, 44 ₂ . Thus, it knits the assembly 45 of knits 44-i, 44 ₂ in at least one elastomer matrix.

In this second embodiment, the assembly 45 forms a monolithic ring having an axis of revolution. The ring is deformable radially, that is to say perpendicular to its axis of revolution, between a rest position and a deformed position. Thus, the assembly 45 is deformed radially from its rest state to its deformed state, then it is axially connected around the blank in its deformed state, then the assembly 45 is released from its deformed state so that the knit grips the blank. Once positioned on the blank, the axis of revolution of the monolithic ring is substantially parallel to and coincides with the axis of the tire.

In a third embodiment, a first band of the elastomer matrix is reported on the blank. Then, the first knit 44-i is reported on the first strip of the elastomer matrix. Then, a second band of the elastomer matrix is reported on the first knit 44-. Then, the second knit 44 _{2 is reported} on the second strip of the elastomer matrix. Then, a third band of the elastomer matrix is reported on the second knit 44 ₂ . Finally, the crown reinforcement 14 and the tread 20 are reported. During the baking of the blank to form the tire 10, the elastomer matrix of the first, second and third strips flows through the assembly. 45 of knits 44-i, 44 ₂ . Thus, it knits the assembly 45 of knits 44-i, 44 ₂ in at least one elastomer matrix.

We will now describe second, third, fourth, fifth and sixth embodiments of the invention respectively with reference to Figures 7, 8 and 9, 10 and 11, 12 and 13, 14 and 15, 16. Elements similar to those described in the previous embodiment are designated by identical references. [0157] Unlike the tire according to the first embodiment, the tire according to the second embodiment of FIGS. 7 and 8 is such as the radial distance d2 between the radially inner end P2 of the assembly 45 and the plane radially. median P4 of the annular structure 26 of the bead 24 is greater than 15 mm.

[0158] Unlike the tire according to the first embodiment, the tire according to the third embodiment of FIGS. 9 and 10 is such that the radially outer end P1 of the assembly 45 is axially external with respect to the end. axially outer P3 of the crown ply 18 radially adjacent to the assembly 45.

The tire according to the fourth embodiment of Figures 11 and 12 comprises two assemblies 45i and 45 ₂ of knits, in this case the knitted assemblies 45 respectively of the second and third embodiments. Each assembly 45i and 45 ₂ includes a radially outer end respectively denoted by P1 and P1 i ₂ and a radially inner end respectively denoted P2 and P2-i _2.

[0160] Unlike the tire according to the first embodiment, the tire according to the fifth embodiment of FIGS. 13 and 14 is such that the radially outer end P1 of the assembly 45 is axially external with respect to the axially outer end P3 of the crown ply 18 radially adjacent to the assembly 45.

[0161] Unlike the tire according to the fourth embodiment of FIGS. 11 and 12, the tire of the sixth embodiment of FIGS. 15 and 16 comprises two assemblies 45 ₁ , 45 ₂ , in this case assemblies 45 and 46 respectively. and third embodiments, arranged axially inside the carcass reinforcement 32.

[0162] COMPARATIVE TESTS

A tire 10 according to the invention was compared with three control tires Q1, Q2, Q3 and three tires T1, T2 and T3 of the state of the art. The tire 10, according to the invention, has an architecture identical to that of the tire according to the first embodiment and comprises two knits each consisting of one or more nylon wire elements. Each control tire Q1, Q2, Q3 has an architecture identical to that of the tire 10, with the difference that each sheet comprises only one knit and not two superposed knitting layers. The characteristics of the knits used are described in Table 1 (properties relating to the maximum force, elongation at break, elongation at 10%, 50% and 100% obtained by applying the ISO 13934 standard. -1: 2013 at or at each knit embedded in the standard elastomer matrix), Table 2 (properties relative to the surface density of meshes according to standard NF EN 14971 of 2006) below and Table 3 (relative properties at maximum strength and forces at 10%, 50% and 100% elongation per row and column) below.

Table 1 Inflatable 10 Q1 Q2 Q3

Nature of strand N47 / 2 N 140/2 N94 / 2 N 140/2

Side

Contexture of knit Jersey Jersey Jersey pique

interlockée

Number of layer (s) of

2 1 1 1 knit

Method used in the

B B B B

standard NF EN 14971

Location Location Location Location

Measuring face

technical technical technical technique

Average results

5.8 4, 1 3 3.6 individual (column / cm)

Average results

9.6 6.4 5 5.7 individual (row / cm)

Surface density

55 26 15 21 (mesh / cm ² )

Table 2

Inflatable 10 Q1 Q2 Q3

Nature of strand N47 / 2 N 140/2 N94 / 2 N 140/2

Side

Contexture of knit Jersey Jersey Jersey pique

interlockée

Number of layer (s) of

2 1 1 1 knit

Surface density

55 26 15 21 (mesh / cm ² )

Main direction X1 (values expressed in N per row

Maximum Strength (N) 43, 1 93.8 74.7 169.8

100% strength

24.2 45, 1 61, 49.6 elongation

Strength at 50% elongation 13.4 28.2 33.4 39.0

Strength at 10% elongation 4.2 9.9 12.3 18.6

Transverse direction Z1 (values expressed in N per column)

Maximum Strength (N) 46.4 67.3 96.7 161, 4

100% strength

28.3 39.2 54.7 70.3 lengthening

Strength at 50% elongation 16.7 25, 1 29 49.4

Strength at 10% elongation 6 8.6 8.4 19.2

Table 3

The tire T1 is identical to the tire 10 with the exception that it is devoid of knitting. The tire T2 comprises, in addition to the elements of the tire T1, a second carcass ply. The tire T3 is identical to the tire T1 with the exception that its sidewalls have a thickness greater than 10 mm compared to that of the sidewalls of the tire T1.

The various tires 10, Q1 to Q3 and T1 to T3 were subjected to a drift thrust test Dz and to a rolling resistance test described below. The mass of each tire 10, Q1 to Q3 and T1 to T3 was also measured.

The results relating to the drift thrust and the mass are given in base 100 with respect to the tire T1. Thus, for the drifting thrust Dz, the greater the value is greater than 100, the better the drift thrust of the tested tire with respect to the tire T1. For the mass, the lower the value, the heavier the tire tested than the tire T1.

The results relating to the rolling resistance are given in base 100 with respect to the tire T3. The lower the value, the higher the rolling resistance. Obviously, we try to have the lowest rolling resistance possible.

To measure the drifting thrust Dz, each tire was rolled at a constant speed of 80 km / h on an appropriate automatic machine ("ground-plane" machine marketed by the MTS company), by varying the load "Z", under a relatively high drift angle of 8 degrees, and the drift thrust was continuously measured and the drift rigidity denoted "D" (corrected for the zero drift thrust) was recorded, by recording using sensors the transverse force on the wheel as a function of this load Z; this gives the rigidity of drift. We then obtain, for a chosen load, here 482 daN, the value reported Dz.

The rolling resistance was measured on a steering wheel, according to the method ISO 87-67 (1992).

The results of these tests were collected in Table 4 below.

Table 4

It is noted that the tire 10 according to the invention has a mass relatively close to that of the tire T1 and in any case lower than that of the tire T2 and especially that of the tire T3. In addition, it is noted that the tire 10 according to the invention has a drift rigidity Dz greater than that of the tires T1 and T2 and close to that of the tire T3. In addition, even if the mass of the tire 10 according to the invention is slightly greater than that of the control tires Q1 to Q3, the drift rigidity of the tire 10 according to the invention is much greater than that of the control tires Q1 to Q3. Thus, the tire 10 according to the invention has excellent drift rigidity and a relatively contained mass. Furthermore, the tire 10 according to the invention has a rolling resistance contained and almost identical to that of the tire T3.

[0173] The invention is not limited to the embodiments described above.

The assembly may be arranged at other positions of the tire than those described above, for example in the crown reinforcement, radially outside the working plies or in the lower zone, for example in the bead.

It is also possible to combine the characteristics of the different embodiments described or envisaged above provided that they are compatible with each other.

Claims

1. Tire (10), characterized in that it comprises at least one assembly (45) of at least two layers of at least one knit (44-i, 44 ₂ ), the two layers being at least partially superimposed on the one on the other, the or each knit (44 ^ 44 ₂ ) comprising:

columns (C1, C2, C3, C4) of loops (B), the loops (B) of one and the same column (C1, C2, C3, C4) being arranged one after the other substantially in one direction general (X1) called principal,

- rows (R1, R2, R3, R4) of loops, the loops (B) of the same row (R1, R2, R3, R4) being arranged next to each other substantially in a general direction (Z1) called transverse,

the or each knit (44-i, 44 ₂ ) having a force at 100% elongation less than or equal to 40 N. row ^"1 and / or 40 N. column ^{" 1} , the force at 100% elongation being determined from a force-elongation curve obtained by applying ISO 13934-1: 2013 to the or each knit (44 ^ 44 ₂ ) embedded in the standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971.

2. A tire (10) according to the preceding claim, wherein the or each knit (44-I, 44 ₂ ) having a force at 100% elongation less than or equal to 35

N. row ^"1 and / or 35 N. column ^{" 1} , the 100% elongation force being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit (44-i, 44 ₂ ) embedded in the standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971.

3. A tire (10) according to any one of the preceding claims, wherein the or each knit (44 ^ 44 ₂ ) has a force at 100% elongation greater than or equal to 0.5 N. row ^"1 and / or 0.5 N. column ^"1 , preferably 5 N. row ^{" 1} and / or 5 N. column ^"1 and more preferably 15 N. row ^{" 1} and / or 15 N. column ^"1 , the force at 100 % elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit (44 _!, 44 ₂ ) embedded in a standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971.

4. A tire (10) according to any one of the preceding claims, wherein the or each knit (44 ^ 44 ₂ ) has a force at 100% elongation less than or equal to 40 N. row ^"1 and / or 40 N. column ^"1 , preferably 35 N. row ^{" 1} and / or 35 N. column ^"1 , the force at 100% elongation being determined from a force-elongation curve obtained by applying the standard ISO 13934 -1: 2013 to the or each knit (44-i, 44 ₂ ) embedded in the standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971.

A tire (10) according to any one of the preceding claims, wherein the or each knit (44 ^ 44 ₂ ) has a force at 50% elongation greater than or equal to 0.5 N. row ^"1 and / or 0.5 N. column ^"1 , preferably 2.5 N. row ^{" 1} and / or 2.5 N. column ^"1 and more preferably 10 N. row ^{" 1} and / or 10 N. column ^"1 , the force at 50% elongation being determined from a force-elongation curve obtained by applying the ISO 13934-1: 2013 standard to the or each knit (44-I, 44 ₂ ) embedded in the elastomer matrix standard and the number of rows and / or columns being measured according to standard NF EN 14971.

6. A tire (10) according to any one of the preceding claims, wherein the or each knit (44-i, 44 ₂ ) has a force at 50% elongation less than or equal to 25 N. row ^"1 and / or N. coli ^"1 , preferably 20 N. row ^{" 1} and / or 20 N. column ^"1 , the 50% elongation force being determined from a force-elongation curve obtained by applying the standard ISO 13934-1: 2013 at or at each knit (44-I, 44 ₂ ) embedded in the standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971.

7. A tire (10) according to any one of the preceding claims, wherein the or each knit (44 ^ 44 ₂ ) has a maximum force greater than or equal to 5 N. row ^"1 and / or 5 N. column ^{" 1} , preferably 10 N. row ^"1 and / or 10 N. column ^{" 1} and more preferably 30 N. row ^"1 and / or 30 N. column ^{" 1} , the maximum force being measured according to standard ISO 13934-1: 2013 applied to the or each knit (44 ^ 44 ₂ ) embedded in the standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971.

8. A tire (10) according to any one of the preceding claims, wherein the or each knit (44-i, 44 ₂ ) has a maximum force less than or equal to 70 N. row ^"1 and / or 70 N. column ^"1 , preferably 60 N. row ^{" 1} and / or 60 N. column ^"1 , the maximum force being measured according to ISO 13934-1: 2013 applied to the or each knit (44-i, 44 ₂ ) embedded in the standard elastomer matrix and the number of rows and / or columns being measured according to standard NF EN 14971.

Pneumatic tire (10) according to any one of the preceding claims, in which the main (X1) and transverse (Z1) directions relate to each other at an angle of between 75 ° and 105 °. preferably between 85 ° and 95 °.

10. A tire (10) according to any one of the preceding claims, wherein the surface density of the mesh or each knit (44 ^ 44 ₂ ), measured according to the standard NF EN 14971, is greater than or equal to 15 meshes. cm ² , preferably 25 mesh, cm ² and more preferably 30 mesh. cm ^"2 .

1 1. A tire (10) according to any one of the preceding claims, wherein the or each knit (441, 442) is made of one or more wire elements of a material selected from a polyester, a polyamide, a polyketone, a polyvinyl alcohol, a cellulose, a mineral fiber, a natural fiber, an elastomeric material or a mixture of these materials.

12. A tire (10) according to any preceding claim, comprising a carcass reinforcement (32) anchored in two beads (24) and radially surmounted by a crown reinforcement (14) itself surmounted by a strip of bearing (20) which is joined to the beads by two flanks (22), each flank (22) comprising the assembly (45).

13. A tire (10) according to the preceding claim, wherein the radially outer end (P1) of the assembly (45) is axially inner to the axially outer end (P3) of a crown ply (18). ) radially adjacent to the assembly (45).

14. A tire (10) according to claim 12 or 13, wherein the axial distance (d1) between the radially outer end (P1) of the assembly (45) and the axially outer end (P3) of the ply. apex (18) radially adjacent to the assembly (45) is greater than or equal to 5 mm, preferably 10 mm and more preferably 15 mm.

15. A tire (10) according to any one of claims 12 to 14, wherein the radially outer end (P1) of the assembly (45) is radially interposed between the carcass reinforcement (32) and the armature of summit (14).

Pneumatic tire (10) according to any one of claims 12 to 15, wherein the carcass reinforcement (32) is anchored in each bead (24) by an upturn around an annular structure (26) of the bead ( 24) to form a forward strand (38) and a return strand (40).

17. A tire (10) according to the preceding claim, wherein the radial distance (d2) between the radially inner end (P2) of the assembly (45) and the radially median plane (P4) of the annular structure (26). bead (24) is less than or equal to 15 mm, preferably 10 mm and more preferably 5 mm.

18. Use of at least one assembly (45) of at least two layers of at least one knit (44-i, 44 ₂ ), the two layers being at least partially superposed on one another, as a reinforcing element of a tire (10), the or each knit (44-I, 44 ₂ ) comprising:

19. A method of manufacturing a tire (10) according to any one of claims 1 to 17, wherein the assembly is embedded (45) in at least one elastomer matrix.