Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
  • B60C9/0007—Reinforcements made of metallic elements, e.g. cords, yarns, filaments or fibres made from metal
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C1/0041—Compositions of the carcass layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
  • B60C9/02—Carcasses
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B1/00—Constructional features of ropes or cables
  • D07B1/06—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core
  • D07B1/0606—Reinforcing cords for rubber or plastic articles
  • D07B1/062—Reinforcing cords for rubber or plastic articles the reinforcing cords being characterised by the strand configuration
  • D07B1/0633—Reinforcing cords for rubber or plastic articles the reinforcing cords being characterised by the strand configuration having a multiple-layer configuration
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
  • B60C2009/0071—Reinforcements or ply arrangement of pneumatic tyres characterised by special physical properties of the reinforcements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
  • B60C2009/0071—Reinforcements or ply arrangement of pneumatic tyres characterised by special physical properties of the reinforcements
  • B60C2009/0085—Tensile strength
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
  • B60C2009/0071—Reinforcements or ply arrangement of pneumatic tyres characterised by special physical properties of the reinforcements
  • B60C2009/0092—Twist structure
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C2200/00—Tyres specially adapted for particular applications
  • B60C2200/06—Tyres specially adapted for particular applications for heavy duty vehicles
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2205/00—Rope or cable materials
  • D07B2205/30—Inorganic materials
  • D07B2205/3021—Metals
  • D07B2205/3025—Steel
  • D07B2205/3046—Steel characterised by the carbon content
  • D07B2205/305—Steel characterised by the carbon content having a low carbon content, e.g. below 0,5 percent respectively NT wires
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2501/00—Application field
  • D07B2501/20—Application field related to ropes or cables
  • D07B2501/2046—Tire cords
• • D—TEXTILES; PAPER
  • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B2101/00—Inorganic fibres
  • D10B2101/20—Metallic fibres
• • D—TEXTILES; PAPER
  • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B2505/00—Industrial
  • D10B2505/12—Vehicles

Definitions

• the present invention relates to a tire, radial carcass reinforcement and more particularly to a tire intended to equip vehicles carrying heavy loads and rolling at a high speed, such as, for example, trucks, tractors, trailers or road buses.
• the carcass reinforcement is anchored on both sides in the bead zone and is radially surmounted by a crown reinforcement consisting of at least two layers, superimposed and formed of son or parallel cables in each layer and crossed from one layer to the next in making with the circumferential direction angles between 10 ° and 45 °.
• Said working layers, forming the working armature can still be covered with at least one so-called protective layer and formed of advantageously metallic and extensible reinforcing elements, called elastic elements.
• It may also comprise a layer of low extensibility wires or metal cables forming with the circumferential direction an angle of between 45 ° and 90 °, this so-called triangulation ply being radially located between the carcass reinforcement and the first ply of plywood.
• so-called working top formed of parallel wires or cables having angles at most equal to 45 ° in absolute value.
• the triangulation ply forms with at least said working ply a triangulated reinforcement, which presents, under the different stresses it undergoes, few deformations, the triangulation ply having the essential role of taking up the transverse compression forces of which the object all the reinforcing elements in the area of the crown of the tire.
• a single protective layer is usually present and its protective elements are, in most cases, oriented in the same direction and with the same angle in absolute value than those reinforcing elements of the radially outermost working layer and therefore radially adjacent.
• the presence of two protective layers is advantageous, the reinforcing elements being crossed from one layer to the next and the reinforcing elements of the radially inner protective layer being crossed with the inextensible reinforcing elements of the radially outer working layer and adjacent to said radially inner protective layer.
• the circumferential direction of the tire is the direction corresponding to the periphery of the tire and defined by the rolling direction of the tire.
• the transverse or axial direction of the tire is parallel to the axis of rotation of the tire.
• the radial direction is a direction intersecting the axis of rotation of the tire and perpendicular thereto.
• the axis of rotation of the tire is the axis around which it rotates in normal use.
• a radial or meridian plane is a plane which contains the axis of rotation of the tire.
• the circumferential mid-plane is a plane perpendicular to the axis of rotation of the tire and which divides the tire into two halves.
• Some current tires are intended to run at high speed and on longer and longer journeys, because of the improvement of the road network and the growth of the motorway network in the world.
• the set of conditions under which such a tire is called to roll undoubtedly allows an increase in the number of kilometers traveled, the wear of the tire being less; on the other hand, the stamina of the latter is penalized.
• the prolonged rolling under particularly severe conditions of the tires thus constructed do indeed show limits in terms of endurance of these tires.
• the elements of the carcass reinforcement are in particular subjected to flexural and compressive stresses during rollings that go against their endurance.
• the cables constituting the reinforcement elements of the carcass layers are in fact subjected to considerable stresses during the rolling of the tires, in particular to repeated bending or variations of curvature inducing at the level of the yarns of friction, and therefore of wear, as well as fatigue; This phenomenon is called "fatigue-fretting".
• said cables must first have good flexibility and high endurance in flexion, which implies in particular that their son have a relatively small diameter, of preferably less than 0.28 mm, more preferably less than 0.25 mm, generally smaller than that of the wires used in conventional cables for tire crown reinforcement.
• the cables of the carcass reinforcement are also subject to so-called "fatigue-corrosion” phenomena due to the very nature of the cables that promote the passage or even drain corrosive agents such as oxygen and moisture. Indeed, the air or water entering the tire for example during a degradation during a cut or simply because of the permeability, even small of the inner surface of the tire, can be driven by the channels formed within the cables because of their structure.
• the inventors have thus given themselves the mission of providing tires for heavy vehicles of the "heavy-weight” type, the endurance performance of the reinforcing elements of the carcass reinforcement remain satisfactory especially in view of the phenomena of "fatigue-corrosion” or “fatigue-fretting-corrosion” whatever the conditions of rolling and whose manufacturing cost remains acceptable.
• a radial carcass reinforcement tire consisting of at least one layer of metal reinforcing elements, said tire comprising a crown reinforcement, itself radially capped. a tread, said tread being joined to two beads via two sidewalls, the metal reinforcing elements of at least one layer of the carcass reinforcement being cables consisting of several steel wires having a carbon content in mass C such that 0.01% ⁇ C ⁇ 0.4%, said cables of at least one layer of the carcass reinforcement having a permeability test with a flow rate of less than or equal to 20 cmVmn, the thickness of rubbery mixture between the inner surface of the tire cavity and the point of a metal reinforcing element of the carcass reinforcement nearest to said inner surface of the cavity being less than or equal to 3.2 mm and said steel wires having a maximum stress before rupture R, expressed in MPa, such that R> 175 + 930.C - 600.1n (d) and R> 1500 MPa, d being the diameter of said steel wires
• the so-called permeability test makes it possible to determine the longitudinal permeability to air of the cables tested, by measuring the volume of air passing through a specimen under constant pressure for a given time.
• the principle of such a test is to demonstrate the effectiveness of the treatment of a cable to make it impermeable to air; it has been described for example in ASTM D2692-98.
• the test is performed on cables extracted directly, by shelling, vulcanized rubber sheets that they reinforce, so penetrated by the cooked rubber.
• the test is carried out on 2 cm of cable length, so coated by its surrounding rubber composition (or coating gum) in the cooked state, in the following manner: it sends air to the cable inlet, under a pressure of 1 bar, and the volume of air at the outlet is measured using a flow meter (calibrated for example from 0 to 500 cm 3 / min).
• the cable sample is locked in a compressed seal (eg a dense foam or rubber seal) in such a way that only the amount of air passing through the cable from one end to the other, along its longitudinal axis, is taken into account by the measure; the tightness of the seal itself is checked beforehand with the aid of a solid rubber specimen, that is to say without cable.
• a compressed seal eg a dense foam or rubber seal
• the average air flow measured (average of 10 test pieces) is even lower than the longitudinal imperviousness of the cable is high.
• the measured values less than or equal to 0.2 cm 3 / min are considered as zero; they correspond to a cable that can be described as airtight (totally airtight) along its axis (ie, in its longitudinal direction).
• This permeability test is also a simple means of indirect measurement of the penetration rate of the cable by a rubber composition.
• the measured flow rate is even lower than the penetration rate of the cable by the rubber is high.
• Cables having a flow rate of less than 20 cm3 / min in the so-called permeability test have a penetration rate greater than 66%.
• the penetration rate of a cable can still be estimated according to the method described below.
• the method consists first of all in eliminating the outer layer on a sample having a length of between 2 and 4 cm, and then measuring in a longitudinal direction and along a given axis the sum of the lengths of rubber mix reported over the length of the sample. These measurements of rubber mix lengths exclude non-penetrated spaces on this longitudinal axis. These measurements are repeated on three longitudinal axes distributed over the periphery of the sample and repeated over five cable samples.
• the first removal step is repeated with the newly outer layer and the length measurements of rubber mix along longitudinal axes.
• An average of all ratios of lengths of rubber mixture on the lengths of the samples thus determined is then carried out to define the rate of penetration of the cable.
• the thickness of the rubbery mixture between the inner surface of the tire cavity and the point of a reinforcing element closest to said surface is equal to the length of the orthogonal projection of the end of the d-point. a reinforcing element closest to said surface on the inner surface of the tire cavity.
• the maximum stress at break or rupture limit corresponds to the force required to break the wire.
• the maximum stress-strain measurements denoted R (in MPa) are carried out according to the ISO 6892 standard of 1984.
• the rubbery mixture enters the tire cavity and the reinforcing elements. of the radially innermost carcass reinforcement layer consisting of at least two layers of rubber mix, the radially innermost rubbery mix layer has a thickness of less than or equal to 1.5 mm.
• this layer is usually composed of butyl so as to increase the seal of the tire and this type of material having a significant cost, the reduction of this layer is favorable.
• the layer of rubber mix radially adjacent to the radially innermost rubbery adhesive layer has a thickness of less than or equal to 1.7 mm.
• the thickness of this layer the components of which make it possible in particular to fix the oxygen of the air, can also be reduced so as to further reduce the cost of the tire.
• each of these two layers are equal to the length of the orthogonal projection of a point of a surface on the other surface of said layer.
• the inventors have demonstrated that a tire thus produced according to the invention leads to improvements in terms of endurance compromise very interesting manufacturing costs. Indeed, the endurance properties with such a tire are improved over the solutions mentioned above especially under particularly severe driving conditions. Furthermore, the thickness of the layer of rubber mix between the carcass reinforcement and the tire cavity being reduced compared to conventional tires and this being one of the most expensive components of the tire, the cost of manufacturing the tire is less than that of a conventional tire.
• the cables of the carcass reinforcement being constituted by several steel wires having a carbon content in mass C such that 0.01% ⁇ C ⁇ 0.4% make it possible to limit the risks of local oxidation of reinforcements of the carcass reinforcement. which could appear in particularly severe driving conditions.
• the values of maximum stress before breaking son according to the invention further promotes the performance in terms of endurance of the tire, the mechanical properties of the carcass reinforcement thus being ensured to withstand attacks of the type shocks that may appear in use on the sidewalls or on the tread.
• the carbon content by mass C being relatively low, it improves the wire wire drawability, that is to say the ability to sufficiently wet the wire by drawing to give it significant mechanical strength properties and in particular a maximum stress before satisfactory rupture. It may thus be possible to reduce the diameter of the wire, and thus lighten the tire, while maintaining sufficient mechanical strength to reinforce the tire.
• the wire according to the invention is much less sensitive to fatigue and corrosion which improves the endurance of the tire and offsets its possible initial deficit in maximum stress before rupture.
• said steel son have a chromium content in Cr mass such as Cr ⁇ 12%.
• chromium Cr makes it possible to obtain a wire having advantages in terms of constraints related to the environment. Indeed, the use of chromium requires the use of expensive specific measures, especially during the recycling of such son, which can be avoided with the wire according to the invention.
• the micro-structure of the steel is integrally ferrite, perlite or a mixture of these microstructures.
• the micro-structure of the steel is devoid of martensite and / or bainite.
• a ferritic-martensitic microstructure causes decohesion between the ferritic and martensitic phases, which is undesirable.
• a martensitic microstructure is not sufficiently ductile to allow wire drawing which would break too frequently.
• ferritic, pearlitic or ferrito-pearlitic micro-structure of another micro-structure in particular martensitic or bainitic, by metallographic observation.
• the ferrito-pearlitic micro-structure exhibits ferrite grains as well as lamellar pearlitic zones.
• the martensitic micro-structure comprises slats and / or needles which those skilled in the art will be able to distinguish between ferrite-pearlitic and pearlitic micro-structures from grains and lamellae.
• the microstructure of the steel is integrally ferrito-pearlitic.
• Said son according to the invention are made of steel, that is to say they consist mainly of (that is to say for more than 50% by weight) or integrally (for 100% by weight) of steel as defined in standard NF EN 10020.
• a steel is a material containing more iron than any other element and whose carbon content is less than 2% and which contains other elements of iron. alloys.
• the steel optionally includes other alloying elements.
• the steel is a non-alloy steel as defined in the NF EN10020 standard.
• the steel comprises, in addition to carbon and iron, other known alloying elements in quantities in accordance with the NF EN 10020 standard.
• the steel is an alloy steel as defined in the NF EN10020 standard.
• the steel comprises, in addition to carbon and iron, other known alloying elements.
• the steel is not a stainless steel as defined in the NF EN10020 standard.
• the steel preferably comprises at most 10.5% by weight of chromium.
• the wire has a carbon content in mass C such that 0.07% ⁇ C ⁇ 0.3%, preferably 0.1% ⁇ C ⁇ 0.3% and more preferably 0.15% ⁇ C ⁇ 0.25%.
• d is greater than or equal to 0.10 mm and preferably 0.12 mm.
• d is less than or equal to 0.40 mm, preferably 0.25 mm, more preferably 0.23 mm and even more preferentially 0.20 mm.
• the diameter d is too large, the flexibility and endurance of the wire are too low for use of the wire in some tire plies, including the carcass reinforcement, for example for a heavy vehicle type.
• the metal reinforcing elements of at least one layer of the carcass reinforcement are metal cables with building layers [L + M] or [L + M + N ] usable as reinforcement element of a tire carcass reinforcement, comprising a first layer C1 to L son of diameter di with L ranging from 1 to 4, surrounded by at least one intermediate layer C2 to M son of diameter d 2 wound together in a helix in a pitch p 2 with M ranging from 3 to 12, said layer C2 being optionally surrounded by an outer layer C3 of N son of diameter d 3 wound together helically in a pitch p 3 with N ranging from 8 to 20.
• the diameter of the son of the first layer of the inner layer (Cl) is between 0.10 and 0.4 mm and the son diameter of the outer layers (C2, C3) is between 0.10 and 0.4 mm.
• the pitch of the winding helix of said son of the outer layer (C3) is between 8 and 25 mm.
• the pitch represents the length, measured parallel to the axis of the cable, at the end of which a wire having this pitch performs a complete revolution around the axis of the cable; thus, if the axis is divided by two planes perpendicular to said axis and separated by a length equal to the pitch of a wire of a constituent layer of the cable, the axis of this wire has in these two planes the same position on the two circles corresponding to the layer of the wire considered.
• the intermediate layer C2 preferably comprises six or seven wires, and the cable according to the invention then has the following preferential characteristics (di, d 2 , d 3 , P2 and p 3 in mm):
• all the son of the layers C2 and C3 are wound in the same direction of torsion, that is to say either in the direction S (disposition "S / S"), or in the Z direction ("Z / Z" layout).
• the winding in the same direction of the layers C2 and C3 advantageously allows, in the cable according to the invention, to minimize the friction between these two layers C2 and C3 and therefore the wear of the son constituting them (since there is no longer cross contact between the son).
• the cable of the invention is a construction layer cable denoted 1 + M + N, that is to say that its inner layer Cl consists of a single wire.
• the invention is preferably implemented with a cable chosen from the cables of structure 1 + 9, 1 + 4 + 8, 1 + 4 + 9, 1 + 4 + 10, 1 + 5 + 9, 1 + 5 + 10, 1 + 5 + 11.1 + 6 + 10, 1 + 6 + 11, 1 + 6 + 12, 1 + 7 + 11, 1 + 7 + 12 or 1 + 7 + 13.
• the cables of the carcass reinforcement have, in the so-called permeability test, a flow rate of less than 10 cmVmn and more preferably less than 2 cmVmn.
• the metal reinforcing elements of at least one layer of the carcass reinforcement are cables with at least two layers, at least one inner layer being sheathed with layer consisting of a non-crosslinkable, crosslinkable or crosslinked rubber composition, preferably based on at least one diene elastomer.
• composition based on at least one diene elastomer is meant in known manner that the composition comprises in majority (i.e. in a mass fraction greater than 50%) this or these diene elastomers.
• sheath according to the invention extends continuously around the layer it covers (that is to say that this sheath is continuous in the "orthoradial" direction of the cable which is perpendicular to its radius), so as to form a continuous sleeve of cross section which is preferably substantially circular.
• the rubber composition of this sheath is crosslinkable or crosslinked, that is to say it comprises by definition a crosslinking system adapted to allow the crosslinking of the composition during its cooking (ie , its hardening and not its fusion); thus, this rubber composition can be described as infusible, since it can not be melted by heating at any temperature.
• iene elastomer or rubber is meant in known manner an elastomer derived at least in part (i.e. a homopolymer or a copolymer) of monomers dienes (monomers carrying two carbon-carbon double bonds, conjugated or not).
• diene elastomers can be classified in known manner into two categories: those known as “essentially unsaturated” and those known as “essentially saturated”.
• the term “diene elastomer” is used herein to mean 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% (%). in moles).
• conjugated diene monomers having a level of units or units of diene origin (conjugated dienes) which is greater than 15% (%). in moles).
• 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 termed "essentially saturated" 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%.
• iene elastomer can more particularly be understood as meaning that may be used in the cable of the invention:
• a ternary copolymer obtained by copolymerization of ethylene, of an ⁇ -olefin having 3 to 6 carbon atoms with a non-conjugated diene monomer having from 6 to 12 carbon atoms for example the elastomers obtained from ethylene, propylene with a nonconjugated diene monomer of the aforementioned type such as in particular 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene;
• the present invention is first implemented with essentially unsaturated diene elastomers, in particular of the type (a) or (b) above.
• the diene elastomer is preferably chosen from the group consisting of polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), the various butadiene copolymers and the various isoprene copolymers. , and mixtures of these elastomers.
• Such copolymers are more preferably selected from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR) and isoprene-copolymers.
• SBIR butadiene-styrene
• the diene elastomer chosen is predominantly (that is to say, for more than 50 phr) consisting of an isoprene elastomer.
• isoprene elastomer is meant in known manner a homopolymer or copolymer of isoprene, in other words a diene elastomer chosen from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR), different isoprene copolymers and mixtures of these elastomers.
• the diene elastomer chosen is exclusively (that is to say, 100 phr) consisting of natural rubber, synthetic polyisoprene or a mixture of these elastomers, the synthetic polyisoprene having a content (mol%) of cis-1,4 bonds preferably greater than 90%, more preferably still greater than 98%.
• blends of this natural rubber and / or these synthetic polyisoprenes with other highly unsaturated diene elastomers, especially with SBR or BR elastomers as mentioned above.
• the rubber sheath of the cable of the invention may contain one or more elastomer (s) diene (s), which (s) last (s) can be used (s) in combination with any type of elastomer synthetic other than diene, or with polymers other than elastomers, for example thermoplastic polymers, these polymers other than elastomers then being present as a minority polymer.
• elastomer (s) diene (s) which (s) last (s) can be used (s) in combination with any type of elastomer synthetic other than diene, or with polymers other than elastomers, for example thermoplastic polymers, these polymers other than elastomers then being present as a minority polymer.
• the rubber composition of said sheath is preferably free of any plastomer and comprises only one elastomer (or mixture of elastomers) diene (s) as a polymeric base
• said composition could also comprise at least a plastomer with a mass fraction x p less than the mass fraction x e of the elastomer (s).
• the following relationship is preferably: 0 ⁇ x p ⁇ 0.5. x e , and more preferably: 0 ⁇ x p ⁇ 0.1. x e .
• the system for crosslinking the rubber sheath is a so-called vulcanization system, that is to say based on sulfur (or a sulfur-donor agent) and a primary accelerator.
• vulcanization based on sulfur (or a sulfur-donor agent) and a primary accelerator.
• vulcanization To this basic vulcanization system may be added various known secondary accelerators or vulcanization activators.
• the sulfur is used at a preferential rate of between 0.5 and 10 phr, more preferably between 1 and 8 phr
• the primary vulcanization accelerator for example a sulfenamide, is used at a preferential rate of between 0.5 and 10 phr, more preferably between 0.5 and 5.0 phr.
• the rubber composition of the sheath according to the invention comprises, in addition to said crosslinking system, all the usual ingredients that can be used in tire rubber compositions, such as reinforcing fillers based on carbon black and / or an inorganic reinforcing filler such as silica, anti-aging agents, for example antioxidants, extender oils, plasticizers or agents facilitating the use of the compositions in the green state, acceptors and donors of methylene, resins, bismaleimides, known adhesion promoter systems of the "RFS" type (resorcinol-formaldehyde-silica) or metal salts, especially cobalt salts.
• reinforcing fillers based on carbon black and / or an inorganic reinforcing filler such as silica such as silica
• anti-aging agents for example antioxidants, extender oils, plasticizers or agents facilitating the use of the compositions in the green state
• the composition of the rubber sheath has, in the crosslinked state, a secant modulus in extension at 10% elongation (denoted M 10), measured according to the ASTM D 412 standard of 1998, less than 20 MPa and more preferably less than 12 MPa, in particular between 4 and 11 MPa.
• the composition of this sheath is chosen identical to the composition used for the rubber matrix that the cables according to the invention are intended to reinforce. Thus, there is no problem of possible incompatibility between the respective materials of the sheath and the rubber matrix.
• said composition is based on natural rubber and it comprises carbon black as reinforcing filler, for example a carbon black of grade (ASTM) 300, 600 or 700 (for example N326, N330, N347, N375, N683, N772).
• ASTM carbon black of grade
• the crown reinforcement of the tire is formed of at least two working crown layers of preferably inextensible reinforcing elements, crossed from one layer to the other by making with the circumferential direction angles between 10 ° and 45 °.
• the crown reinforcement further comprises at least one layer of circumferential reinforcing elements.
• a preferred embodiment of the invention further provides that the crown reinforcement is completed radially on the outside by at least one additional layer, called protective layer, of so-called elastic reinforcing elements, oriented relative to the direction. circumferential with an angle between 10 ° and 45 ° and in the same direction as the angle formed by the inextensible elements of the working layer which is radially adjacent thereto.
• the protective layer may have an axial width smaller than the axial width of the least wide working layer.
• Said protective layer may also have an axial width greater than the axial width of the narrower working layer, such that it covers the edges of the narrower working layer and, in the case of the radially upper layer, being the smallest, as coupled, in the axial extension of the additional reinforcement, with the most wide over an axial width, to be then, axially outside, decoupled from said widest working layer by profiles of thickness at least equal to 2 mm.
• the protective layer formed of elastic reinforcing elements may, in the case mentioned above, be on the one hand possibly decoupled from the edges of said least wide working layer by profiles of thickness substantially less than the thickness. profiles separating the edges of the two working layers, and have on the other hand an axial width less than or greater than the axial width of the widest vertex layer.
• the crown reinforcement may be further completed, radially inwardly between the carcass reinforcement and the nearest radially inner working layer. of said carcass reinforcement, by a triangulation layer of steel non-extensible reinforcing elements making, with the circumferential direction, an angle greater than 60 ° and in the same direction as that of the angle formed by the reinforcing elements of the layer radially closest to the carcass reinforcement.
• FIGS. 1 to 2 represent: FIG. 1, a meridian view of a diagram of FIG. a tire according to one embodiment of the invention;
• FIG. 2 is an enlarged partial view of part of the diagram of FIG.
• the tire 1, of dimension 295/80 R 22.5 comprises a radial carcass reinforcement 2 anchored in two beads 3, around rods 4.
• the carcass reinforcement 2 is formed of a single layer of metal cables 11 and two calendering layers 13.
• the carcass reinforcement 2 is shrunk by a crown reinforcement 5, itself capped with a tread 6.
• the crown reinforcement 5 is formed radially of the inside outside: a triangulation layer formed of non-shrunk, non-shrunk, angled metal cables 9.28, oriented at an angle equal to 65 °, of a first working layer formed of unstretchable 11.35 inextensible metal cables, continuous over the entire width of the web, oriented at an angle equal to 26 °, - a second working layer formed of unstretchable 11.35 unstretchable metal cables, continuous over the entire width of the web, oriented at an angle equal to 18 ° and crossed with the cables of the first working layer, a protective layer formed of non-shrunken resilient metal cables 6.35, continuous over the entire width of the sheet, oriented at an angle equal to 18 ° in the same direction as the metal cables of the second layer of work.
• FIG. 2 illustrates an enlargement of the zone 7 of FIG. 1 and indicates in particular the thickness E of rubber mix between the inner surface 10 of the tire cavity 8 and the point 12 of a reinforcing element 11. closer to said surface 10.
• This thickness E is equal to the length of the orthogonal projection of the point 12 of a reinforcing element 11 closest to said surface 10 on the surface 10.
• This thickness E is the sum of the thicknesses of the different rubber mixes set up between said reinforcement element 11 of the carcass reinforcement 2; this is on the one hand the thickness of the radially inner calender layer 13 of the carcass reinforcement and, on the other hand, the thicknesses e 1 , e 2 of the various layers 14, 15 of rubbery mixture forming the wall 1.
• thicknesses e 1 , e 2 are also equal to the length of the orthogonal projection of a point of a surface on the other surface of the respective layer 14 or 15 respectively. Thicknesses are made on a cross-section of the tire, which is consequently not mounted and not inflated.
• the measured value of E is equal to 2.4 mm.
• the values of ei and Q 2 are equal to 1.4 mm and 1 mm respectively.
• the carcass reinforcement cables of the tire 1 are cables with structure layer 1 + 6 + 12, not shrunk, consisting of a central core formed of a wire, an intermediate layer formed of six wires and an outer layer of twelve wires.
• the steel son constituting the carcass reinforcement cables have a carbon content in mass C equal to 0.21%.
• the maximum stress before breaking of the steel wires constituting the carcass reinforcement cables is equal to 2750 MPa.
• the core of the cables consisting of the central core formed of a wire and the intermediate layer formed of the six son is sheathed by a rubber composition based on unvulcanized diene elastomer (in the green state).
• the sheathing is obtained via an extrusion head of the core consisting of the central core formed of a wire surrounded by six son of the intermediate layer. Then, a final operation of twisting or wiring the 12 son of the outer layer around the core and sheathed allows to finish the cables.
• the penetrability of the carcass reinforcement cables thus produced is equal to 95%.
• tires P made according to the invention in accordance with the representation of FIGS. 1 and 2, and others with so-called reference tires R 1.
• These reference tires R differ from the tires P according to the invention by cables of the carcass reinforcement comprising a cladding layer around the inner layers but the steel wires constituting the carcass reinforcement cables present a carbon content in mass C equal to 0.58% and a maximum stress before rupture equal to 2830 MPa.
• Endurance tests in rolling on an outer wheel of circumference equal to 8.5 meters were made by imposing on the tires a load of 4176 daN and a speed of 40 km / h, with an inflation of tires doped with oxygen at 10.2. bars. These tests are performed in an air-conditioned chamber at 15 ° C. The tests were carried out for the tires according to the invention with conditions identical to those applied to the reference tires. Rollings are stopped as soon as the tires have degradations of the carcass reinforcement.
• the mileage traveled is measured until the tire has a degradation.
• the measurements illustrated below are reduced to a base 100 for the reference tire.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Tires In General (AREA)
• Ropes Or Cables (AREA)

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Publications (1)

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• 2015
  • 2015-09-04 FR FR1558203A patent/FR3040656A1/fr active Pending
• 2016
  • 2016-09-02 EP EP16759796.2A patent/EP3344475A1/de not_active Withdrawn
  • 2016-09-02 US US15/757,211 patent/US20180250987A1/en not_active Abandoned
  • 2016-09-02 CN CN201680050359.7A patent/CN108025596A/zh not_active Withdrawn
  • 2016-09-02 WO PCT/EP2016/070704 patent/WO2017037226A1/fr active Application Filing

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