• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention relates to the top of a tire for a heavy civil engineering vehicle and aims to desensitize this summit to aggression. This objective has been achieved by a tire (1) comprising a tread (2) having a surface laminating ratio TL, expressed in m / m2, equal to the ratio between the cumulative length LD of the cutouts (21) and the area A of the radially outer surface (23) of the tread (2), and a protective armature (4) comprising at least two protective layers (41, 42) formed of elastic metal reinforcements and having a maximum breaking strength Rmax, expressed in daN / m, such that the TL surface area of the tread (2) is at least 3 m / m 2 and a coupling ratio C equal to the ratio between the maximum breaking strength Rmax and the level of surface laminating TL, is at least equal to 30000 daN.
    公开号:FR3044967A1
    申请号:FR1562374
    申请日:2015-12-15
    公开日:2017-06-16
    发明作者:Olivier Spinnler；Franck Nugier；Alain Domingo
    申请人:Michelin Recherche et Technique SA Switzerland ；Compagnie Generale des Etablissements Michelin SCA；Michelin Recherche et Technique SA France；
    IPC主号:
    专利说明:

    The present invention relates to a radial tire intended to equip a heavy vehicle type civil engineering and, more particularly, the top of such a tire.
    [0002] A radial tire for a heavy vehicle of the civil engineering type is designed to be mounted on a rim whose nominal diameter, according to the ETRTO standard (European Tire and Rim Technical Organization), is at least equal to 25 inches. Although not limited to this type of application, the invention is more particularly described with reference to a large radial tire intended, for example, to be mounted on a dumper, a vehicle for transporting materials extracted from quarries or surface mines. Large radial tire means a tire intended to be mounted on a rim whose nominal diameter is at least equal to 49 inches and can reach 57 inches or 63 inches.
    A tire having a geometry of revolution with respect to an axis of rotation, the geometry of the tire is generally described in a meridian plane containing the axis of rotation of the tire. For a given meridian plane, the radial, axial and circumferential directions respectively designate the directions perpendicular to the axis of rotation of the tire, parallel to the axis of rotation of the tire and perpendicular to the meridian plane.
    In what follows, the expressions "radially inner", respectively "radially outer" mean "closer", respectively "further from the axis of rotation of the tire". By "axially inner", respectively "axially outer", is meant "closer" or "furthest from the equatorial plane of the tire" respectively, the equatorial plane of the tire being the plane passing through the middle of the running surface of the tire and perpendicular to the axis of rotation of the tire.
    [0005] A radial tire comprises radially from the outside towards the inside a tread, a crown reinforcement and a carcass reinforcement. The assembly constituted by the tread and the crown reinforcement is the crown of the tire.
    The tread is the part of the crown of the tire intended to come into contact with a ground through a rolling surface and to be worn. The tread comprises at least one elastomeric material and a more or less complex system of cutouts separating elements in relief, called carving, in particular to ensure a satisfactory performance in adhesion.
    [0007] The tread cuts may have any type of orientation with respect to the circumferential direction of the tire. The longitudinal or circumferential cuts forming, with the circumferential direction, an angle at most equal to 45 ° are usually distinguished, and the axial or transverse cuts forming, with the circumferential direction, an angle of at least 45 °. Among the cuts, there are grooves and incisions. A groove is a cutout defining a space delimited by material walls opposite and distant from each other, so that said walls can not come into contact with each other during the passage of the tread in contact with the ground, when the tire is under running conditions under recommended nominal load and pressure conditions. An incision is a cutout defining a space delimited by material walls coming into contact with each other during rolling.
    The tread is generally characterized geometrically by an axial width Wt and a radial thickness Ηχ. The axial width Wj is defined as the axial width of the contact surface of the tread of the new tire with a smooth ground, the tire being subjected to pressure and load conditions as recommended, for example, by the standard ETRTO (European Tire and Rim Technical Organization). The radial thickness HT is defined, by convention, as the maximum radial depth measured in the cutouts. In the case of a tire for a heavy vehicle of civil engineering type, and by way of example, the axial width Wt is at least equal to 600 mm and the radial thickness Ηχ is at least equal to 60 mm.
    The tread is also often characterized by a volume notching rate TEV, equal to the ratio between the total volume Vd of the cutouts, measured on the free tire that is to say not mounted and not inflated, and the sum of the total volume Vd of the cuts and the total volume Vr of the relief elements delimited by these cuts. The sum Vd + Vr corresponds to the volume comprised radially between the running surface and a bottom surface, translated from the running surface radially inwards by a radial distance equal to the radial thickness Ηχ of the tread. This level of voluminal notching in TEV, expressed in%, conditions in particular the wear performance, the volume of rubber available, and the performance in longitudinal and transverse adhesion, by the presence of respectively transverse and longitudinal edges and cutouts with the ability to store or discharge water or sludge.
    In the present invention, effective cuts are called cutouts whose width Wd is at most equal to 20% of their radial depth Ηχ> and whose radial depth Ηχ> is at least equal to 50% of the thickness. radial HT. These are groove type cutouts, allowing air circulation in the tread, not incisions.
    These effective cutouts, having a cumulative length Ld, measured on a radially outer surface of the tread strip, make it possible to define a surface laminating ratio TL, expressed in m / m 2, equal to the ratio between the cumulative length L d of the cutouts. effective and the area A of the radially outer surface of the tread equal to 2 nRE * WTj where RE is the outer radius of the tire.
    [0012] Radially inside the tread, the crown reinforcement of a radial tire for a heavy vehicle of the civil engineering type comprises a superposition of crown layers extending circumferentially, radially inside the tread. tread and outside the carcass reinforcement. Each crown layer consists of generally metallic reinforcements, parallel to each other and coated with an elastomeric material obtained by mixing commonly called elastomeric mixture.
    Among the top layers, it is usual to distinguish the protective layers, constituting the protective armature and radially outermost, the working layers constituting the working armature and radially inner to the armature of protection, and the hooping layers, most often radially between the working reinforcement and the carcass reinforcement but may be radially between two working layers or radially between the protective reinforcement and the reinforcement of work .
    The protective armature, consisting of at least two layers of protection, essentially protects the working layers from mechanical or physicochemical attacks, likely to propagate through the tread radially inwardly of the tire. The protective reinforcement often comprises two radially superimposed protective layers formed of elastic metal reinforcements, parallel to each other in each layer and crossed from one layer to the next, forming, with the circumferential direction, angles the value of which absolute is generally between 15 ° and 45 °, and preferably between 20 ° and 40 °.
    The reinforcement of work, consisting of at least two working layers, has the function of belt the tire and give stiffness and handling to the tire. The reinforcement takes up both mechanical loading of the tire, generated by the inflation pressure of the tire and transmitted by the carcass reinforcement, and mechanical stresses of rolling, generated by the rolling of the tire on a ground and transmitted by the rolling band. The reinforcement must also withstand oxidation and shocks and perforations, thanks to its intrinsic design and that of the protective reinforcement. The working frame usually comprises two radially superposed working layers formed of non-elastic metal reinforcements, parallel to one another in each layer and crossed from one layer to the next, forming, with the circumferential direction, angles whose absolute value is generally between 15 ° and 45 °, and preferably between 15 ° and 40 °.
    The hooping frame, consisting of at least one shrink layer, limits the radial deformations of the top inflation and contributes to the stiffening of the top. The hooping frame often comprises two radially superimposed hooping layers, formed of non-elastic or elastic metal reinforcements, parallel to each other in each layer and crossed from one layer to the next, forming, with the circumferential direction, angles whose absolute value is not more than 15 °, preferably not more than 8 °.
    A metal reinforcement is mechanically characterized by a curve representing the tensile force (in N), applied to the metal reinforcement, depending on the relative elongation (in%) of the metal reinforcement, said force-elongation curve. From this force-elongation curve are deduced tensile mechanical characteristics, such as the structural elongation As (in%), the total elongation at break At (in%), the breaking force Fm (maximum load in N ) and the breaking strength Rm (in MPa), these characteristics being measured according to ISO 6892 of 1984.
    The total elongation at break of the metal reinforcement is, by definition, the sum of its structural, elastic and plastic elongations (At = As + Ae + Ap). The structural elongation As results from the relative positioning of the constituent metal son of the metal reinforcement under a low tensile force. The elastic elongation Ae results from the elasticity of the metal of the metal wires, constituting the metal reinforcement, taken individually (Hooke's law). The plastic elongation Ap results from the plasticity (irreversible deformation beyond the elastic limit) of the metal of these metal wires taken individually. These different elongations and their respective meanings, well known to those skilled in the art, are described, for example, in the documents US5843583, WO2005 / 014925 and WO2007 / 090603.
    It also defines, at any point of the force-elongation curve, an extension module (GPa) which represents the slope of the line tangent to the force-elongation curve at this point. In particular, the term elastic modulus in extension or Young's modulus, the module in extension of the elastic linear part of the force-allo ngement curve.
    Among the metal reinforcements, there are usually elastic metal reinforcements, such as those most often used in the protective layers, and non-elastic metal reinforcements, such as those generally used in the working layers.
    An elastic metal reinforcement is characterized by a structural elongation As at least equal to 1% and a total elongation at break At at least equal to 4%. In addition, an elastic metal reinforcement has an elastic modulus in extension at most equal to 150 GPa, and usually between 40 GPa and 150 GPa, preferably between 70 GPa and 110 GPa. Its breaking strength Fm is generally at least equal to 500 daN.
    An elastic metal reinforcement is often a multi-strand elastic cable, that is to say formed of an assembly of several strands, and whose structure is, for example, of the type K * (L + M) in the frequent case where the strands are two-layer strands. K is the number of two-layer strands, L is the number of wires constituting the inner layer of a strand and M is the number of wires constituting the outer layer of a strand. A two-layer strand is usually obtained by helically winding M son constituting an outer layer of the strand around L son constituting an inner layer of the strand.
    For a multi-strand elastic cable, the structural elongation As results from the construction and even aeration of the multi-strand cable and / or its elementary strands as well as their own elasticity, if necessary of a pre-formation. imposed on one or more of these strands and / or constituent wires. The aeration of the cable results, on the one hand, from the spacing of the wires with respect to the axial direction (direction perpendicular to the direction of the axis of the strand) and, on the other hand, from the spacing of the strands by relative to the axial direction (direction perpendicular to the direction of the axis of the cable).
    A non-elastic metal reinforcement is characterized by a total elongation, under a tensile force equal to 10% of the breaking force Fm, at most equal to 0.2%. Furthermore, a non-elastic metal reinforcement has an elastic modulus in extension usually between 150 GPa and 200 GPa.
    Regarding the use of a heavy vehicle tire type civil engineering, it is intended to carry high loads and to ride on slopes covered with pebbles of various sizes.
    Running under high load will generate, particularly in the top of the tire, high temperatures likely to cause damage to the top components and limit its endurance, and therefore the life of the tire. In particular, high temperatures are generated in the working frame whose working cups can separate under the action of heat: this is known as thermal cleavage. The reduction of the thermal level of the tire crown to combat thermal cleavage is a constant concern of the tire designer.
    Furthermore running on tracks covered with pebbles, which will indent the tread, will generate aggression from the top of the tire by these indenters. More precisely, the indentors will on the one hand attack the tread, on the other hand get stuck, if necessary, in the tread cuts. The jamming of pebbles in the trenches of the tread, usually called pebble retention, is capable of initiating cracks in the bottom of cutouts which will propagate radially towards the inside of the crown of the tire to reach the crown reinforcement, and more precisely the protective armature, which will degrade over time and break: which will reduce the life of the tire. This phenomenon is all the more marked that the tread cuts are numerous and / or have a large volume, that is to say that the rate of notching volume of the tread is high, typically at least equal to 12%. This problem of attacks of the summit is therefore also a concern of the tire designer.
    To reduce the thermal level of the crown of the tire, a known solution is to notch the tread at a sufficient level, that is to say to have a high rate of notching volumic, to lower the temperatures generated in the summit at an acceptable level. The higher the volume notching rate, the more the thermal level of the top will be decreased, but the higher the risk of being attacked by the indentors present on the tracks.
    The inventors have set themselves the goal of desensitizing the crown of a radial tire for a heavy vehicle of the civil engineering type to aggressions by indentors, in particular in the case of a tread having a high rate of notching of volume. .
    This object has been achieved, according to the invention, by a tire for a heavy vehicle type civil engineering comprising a tread and a crown reinforcement, radially inner to the tread: -the tread, having a radial thickness Ht at least equal to 60 mm, comprising cutouts, having a width Wd and a radial depth Hd, and relief elements, separated by the cutouts, the cutouts, the width Wd of which is at most 20 % of the radial depth Hd and whose radial depth HD is at least equal to 50% of the radial thickness Ht, said effective cutouts, having a cumulative length Ld, measured on a radially outer surface of the tread, -the strip having a surface laminating ratio TL, expressed in m / m 2, equal to the ratio of the cumulative length L d of the effective cuts and T A of the radially outer surface of the tread equal to 21Re * Wt; where Re is the outer radius of the tire, the crown reinforcement comprising a protective armature, a work armature and a shrinking armature, the radially outermost protection armature comprising at least two protective layers. , formed of elastic metal reinforcements, forming, with the circumferential direction, an angle of between 15 ° and 45 °, each protective layer having a breaking strength R per unit of layer width, expressed in daN / m, Rmax being the maximum value of the rupture resistors R of the protective layers, the working armature comprising at least two working layers, formed of non-elastic metal reinforcements, crossed from one working layer to the next and forming, with a circumferential direction of the tire, an angle between 15 ° and 45 °, -the shrinking armature, comprising at least one shrink layer, formed of metal reinforcements, forming, with the circumferential direction, an angle at most equal to 15 °, the TL surface area laminating ratio being at least equal to 3 m / m 2 and a coupling ratio C equal to the ratio between the maximum value R max R-strength resistors R protective layers and the TL surface area laminating rate of the tread, being at least equal to 30000 daN.
    A surface tread TL level of the minimum tread, that is to say, a cumulative length Ld minimum efficient cutouts per unit area, ensures minimal ventilation efficient truncations of the tread, so a cooling of the tread and, consequently, a decrease in the internal temperatures of the crown, in particular at the axial ends of the working layers, preferential zones of initiation of thermal cleavage.
    A coupling ratio C, equal to the ratio between the maximum value Rmax of the rupture resistors R of the protective layers and the surface saturation level TL of the tread, is minimal for the strength of the reinforcement. protection, for a given TL laminating ratio.
    The combination of these two essential characteristics makes it possible to obtain a satisfactory compromise between the thermal level of the crown and the resistance to attack from the summit that may initiate cracking from the tread radially towards the inside of the crown. of the tire.
    Preferably the coupling ratio C is at least equal to 40000 daN. A higher coupling ratio C strengthens resistance to attack from the summit, so allows use on even more aggressive floors at the same level of cooling of the summit.
    More preferably the coupling ratio C is at most equal to 120000 daN. Beyond this coupling ratio, the maximum value Rmax of the rupture resistances R of the protective layers requires, at the level of the protective reinforcement, a level of reinforcement that can be obtained with large diameter metal reinforcements, involving layers of protection of great thickness, likely to degrade the thermal level of the summit.
    Advantageously, the TL laminating rate of the tread is at least equal to 3.5 m / m. The ventilation of the effective tread cuts is improved by a higher TL laminating rate.
    Still advantageously the TL laminating rate of the tread is at most equal to 9 m / m2. Beyond this level of TL laminating, the cumulative length Ld efficient cutting per unit area, therefore the number of effective cuts per unit area, may sensitize the tread attacks to an unacceptable level. On the one hand, the number of crack initiation zones in the bottom of cutouts becomes important. On the other hand, because of the large number of cuts, the dimensions of the relief elements decrease and therefore their stiffness decreases, which increases the risk of tearing off the elements in relief.
    The maximum value Rmax of the rupture resistors R of the protective layers is advantageously at least equal to 150000 daN / m, preferably at least 160000 daN / m. This makes it possible to guarantee satisfactory cut resistance to the protective layers concerned.
    According to a first advantageous embodiment of the protective armature, the breaking strength R of the most radially outer protective layer is equal to the maximum value Rmax of the rupture resistances R of the protective layers. The most radially outer protective layer is the first barrier to indenter penetration. This makes it possible to optimize the cut resistance of the protective reinforcement.
    According to a second preferred embodiment of the protective armature, the breaking strength R of each protective layer is equal to the maximum value Rmax of the rupture resistors R of the protective layers. This makes it possible to maximize the cut resistance of the protective reinforcement.
    According to a third advantageous embodiment of the protective armature, the minimum value Rmjn of the breaking resistors R of the protective layers is such that the ratio Rmin / TL is at least equal to 30000 daN. In other words, all the protective layers have a breaking strength R such that the Rmjn / TL ratio is at least 30000 daN. This makes it possible to obtain a satisfactory compromise between the thermal level of the crown and the resistance to cuts of the protective reinforcement.
    According to a preferred embodiment of the metal reinforcements of the protective layers, the elastic metal reinforcements of the protective layers are multistrand cables, consisting of a single layer of N strands, N being between 3 and 5, each strand being made of metal wires. This type of metal reinforcements is characterized by good penetration ability of an elastomeric coating mixture, which guarantees a good resistance to corrosion and thus an improvement in the endurance of the protective reinforcement.
    According to a first variant of the preferred embodiment of the metal reinforcements of the protective layers, each strand of formula (M + P) comprises an inner layer of M metal wires and an outer layer of P metal wires wound around it. of the inner layer. Each strand is thus made of two concentric layers of metal son.
    According to a particular example of the first variant of the preferred embodiment of the metal reinforcements of the protective layers, the elastic metal reinforcements of the protective layers are multi-conductor cables, of formula 4 * (3 + 8) * 0.35, made up of a single layer of 4 strands, each strand comprising an inner layer of 3 metal wires and an outer layer of 8 metal wires wound around the inner layer, and each strand being made of metal wires with a diameter of 0.35 mm.
    According to another particular example of the first variant of the preferred embodiment of the metal reinforcements of the protective layers, the elastic metal reinforcements of the protective layers are multistrand cables, of formula 4 * (4 + 9) * 0.26, consisting of a single layer of 4 strands, each strand comprising an inner layer of 4 metal wires and an outer layer of 9 metal wires wound around the inner layer, and each strand being made of metal wires with a diameter of 0.26 mm.
    According to a second variant of the preferred embodiment of the metal reinforcements of the protective layers, each strand, of formula (M + N + P), comprises an intermediate layer of N metal wires wound around the inner layer of M son. metallic, the outer layer of P metal wires being wound around the intermediate layer of N metal wires. Each strand is thus made of three concentric layers of metal son.
    Preferably, the outer layer of P metal son is unsaturated. By definition, an unsaturated layer of yarns is such that there is sufficient space in this layer to add at least one (P + 1) th yarn of the same diameter as the P yarns of the layer, several yarns then being able to contact each other.
    Also preferably the diameter of the constituent son of each strand is at least equal to 0.22 mm, preferably at least equal to 0.26 mm.
    The elastic metal reinforcements of the protective layers have, in the air permeability test, an average air flow rate of less than 30 cm3 / min. This criterion characterizes the penetration of metallic wire-type reinforcements by the elastomeric coating mixture. The lower the average air flow rate, the more the metal cables are penetrated, which improves their resistance to endurance, given a low air circulation, and therefore oxygen, corrosion factor, inside. reinforcements.
    As regards the air permeability test, this test makes it possible to determine the longitudinal permeability to air of the metal 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, well known to those skilled in the art, is to demonstrate the effectiveness of the treatment of a wire rope to make it impermeable to air; it has been described for example in ASTM D2692-98.
    The test is carried out either on metal cables extracted tires, so already coated from the outside by an elastomeric mixture or rubber composition in the cooked state, or on raw metal cables manufacturing.
    In the second case, the raw metal cables must be previously coated from the outside with a rubber compound called coating gum. For this, a series of 10 cables arranged in parallel (inter-cable distance: 20 mm) is placed between two ski ms (two rectangles of 80 x 200 mm) of a raw rubber composition, each skim having a 3.5 mm thick; the whole is then locked in a mold, each of the metal cables being maintained under a sufficient tension (for example 2 daN) to ensure its straightness during the establishment in the mold, using clamping modules; then the vulcanization (baking) is carried out for 40 min at a temperature of 140 ° C and a pressure of 15 bar (rectangular piston 80 x 200 mm). After which, the assembly is demolded and cut 10 pieces of metal cables thus coated, in the form of parallelepipeds of dimensions 7x7x20 mm, for characterization.
    A conventional rubber composition for a tire, based on natural rubber (peptized) and carbon black N330 (65 phr), comprising the following usual additives: sulfur (7 phr), is used as a coating rubber. , sulfenamide accelerator (1 phr), ZnO (8 phr), stearic acid (0.7 phr), antioxidant (1.5 phr), cobalt naphthériate (1.5 phr) (phr parts per hundred parts by weight) elastomer); the extension module at 10% elongation E10 of the coating gum is approximately 10 MPa.
    The test is carried out on a 2 cm length of wire rope, therefore coated by its surrounding rubber composition (or coating gum) in the cooked state, in the following manner: air is sent to the At the inlet of the cable, under a pressure of 1 bar, the volume of air at the outlet is measured using a flow meter (calibrated, for example, from 0 to 500 cm 3 / min). During the measurement, the wire rope 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 wire rope from one end to the other 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.
    The average air flow measured (average of 10 test pieces) is even lower than the longitudinal imperviousness of the wire rope is high. As the measurement is made with an accuracy of ± 0.2 cm3 / min, measured values less than or equal to 0.2 cm3 / min are considered as zero; they correspond to a metal cable which can be qualified as airtight (totally sealed) to the air along its axis (that is to say in its longitudinal direction).
    According to an advantageous embodiment of the protective layers, the elastic metal reinforcements of the protective layers are distributed at an average pitch of between 3.5 mm and 5 mm.
    According to another advantageous embodiment of the invention, the set of cutouts having a total volume Vd and the set of relief elements having a total volume Vr, the tread having a volume notching rate. TEV, expressed in%, equal to the ratio between the total volume Vd of the cuts and the sum of the total volume Vd of the cutouts and the total volume of the elements in relief, the voiding volume level TEV of the tread is at least equal at 12%, preferably at least 14%. To have effective thermal ventilation of the tread, the cuts must both be sufficient, which results in a minimum TL sanding rate, and have a sufficient volume, which results in a notch rate minimal TEV volume.
    The characteristics of the invention will be better understood with reference to FIGS. 1 and 2, schematic and not to scale: FIG. 1: half-section, in a meridian plane, of a tire peak for heavy vehicle of the civil engineering type, according to the invention -figure 2: domain of the maximum breaking strengths Rmax as a function of the TL laminating rate of the tread for a heavy vehicle tire of the civil engineering type, according to the invention.
    In Figure 1, there is shown a meridian half-section, in a YZ plane of the top of a tire 1 for a heavy vehicle type civil engineering comprising a tread 2 and a crown reinforcement 3, radially inner to tread 2. The tread 2, having a radial thickness HT at least equal to 60 mm, comprises cutouts 21, having a width Wd and a radial depth Hd, and relief elements 22, separated by the cutouts. 21. The cutouts 21, whose width Wd is at most equal to 20% of the radial depth Hd and whose radial depth HD is at least equal to 50% of the radial thickness Ht, said effective cutouts, have a cumulative length. Ld (not shown in the figure), measured on a radially outer surface 23 of the tread band 2. The tread 2 has a surface laminating ratio TL, expressed in m / m 2, equal to the ratio between the cumulative length Ld of the Découp effective areas 21 and the area A of the radially outer surface 23 of the tread equal to 2HRe * Wt, where Re is the outside radius of the tire measured in the equatorial plane XZ, between revolution Y Y 'and the surface radially outer 23 of the tread 2 or rolling surface. Radially inside the tread 2, the crown reinforcement 3 comprises a protective armature 4, a working frame 5 and a hooping frame 6. The radially outermost protective armature 4 comprises two protective layers (41, 42) formed of elastic metal reinforcements, forming, with the circumferential direction XX ', an angle of between 15 ° and 45 °. Each protective layer (41, 42) has a breaking strength R per unit of layer width, expressed in daN / m, where Rmax is the maximum value of the rupturing resistors R of the protective layers (41, 42). The working armature 5 comprises two working layers (51, 52), formed of non-elastic metal reinforcements, crossed from one working layer to the next and forming, with the circumferential direction XX ', an angle of between 15 ° and 45 °. The hooping frame 6 comprises two hooping layers (61, 62), formed of metal reinforcements, forming, with the circumferential direction XX ', an angle at most equal to 15 °. According to the invention, the TL surface area laminating ratio of the tread 2 is at least 3 m / m 2 and a coupling ratio C equal to the ratio between the maximum value Rmax of the rupture resistors R of the protective layers. (41, 42) and TL surface laminating rate of the tread 2, is at least equal to 30000 daN.
    FIG. 2 represents the domain of the maximum breaking strengths Rmax as a function of the level of TL laminating of the tread for a heavy vehicle tire of the civil engineering type according to the invention. According to the invention, the TL surface area laminating ratio is at least 3 m / m 2 and a coupling ratio C equal to the ratio between the maximum value Rmax of the rupture resistors R of the protective layers and the TL surface area laminating rate of the tread 2 is at least equal to 30000 daN. Therefore, the field of the invention is defined by the maximum breaking strengths Rmax at least equal to 30000 * TL, where TL is the area laminating ratio, with TL at least equal to 3 m / m2. On the abscissa axis of the graph of FIG. 2, is represented the minimum value of the TL surface area laminating ratio of the tread equal to 3 m / m 2. On the y-axis of the graph of FIG. 2, the minimum value of the maximum resistance Rmax of the rupture resistances R of the protective layers equal to 90000 daN / m is represented, corresponding to the minimum coupling ratio C equal to 30000 daN. On the graph are also represented a first embodiment of the invention II in which the surface laminating rate TL is equal to 4.2 m / m 2 and the maximum value Rmax of the rupture resistors R of the protective layers is equal to 160000 daN / m, the protective layers comprising multi-tone elastic cables of formula 4 * (4 + 9) * 0.26, and a second embodiment of the invention 12 in which the surface laminating ratio TL is equal to 4.2 m / m 2 and the maximum value Rmax of the rupture resistors R of the protective layers is equal to 200000 daN / m, the protective layers comprising multi-tone elastic cables of formula 4 * (3 + 8) * 0.35. FIG. 2 also shows an example of the state of the art E, characterized by a surface laminating ratio TL equal to 1.6 m / m and a maximum value Rmax of the rupture strengths R of the protective layers equal to 102000 daN / m, therefore outside the scope of the invention.
    The invention has more particularly been studied for a tire size 40.00R57. Two examples of a tire according to the invention II and 12 and a tire of the state of the art E, taken in reference, were compared by the inventors.
    In the case studied, the tires respectively of the state of the art E and according to the invention II and 12 have a crown reinforcement comprising, radially from the outside towards the inside, a protective reinforcement constituted by two protective layers with elastic metal reinforcements, a working frame consisting of two working layers with non-elastic metal reinforcements and a hooping reinforcement consisting of two shrink layers with non-elastic metal reinforcements. With regard to the protective reinforcement, the elastic metal reinforcements of the two protective layers, crossed from one layer to the next, form, with the circumferential direction XX ', an angle equal to 24 °, for the tire of the state of the technique E, and an angle equal to 33 °, for the tires according to the invention II and 12. Concerning the working reinforcement, the non-elastic metal reinforcements of the two working layers, crossed from one layer to the next, form, with the circumferential direction XX ', angles respectively equal to 33 ° and 19 °, for the tire of the state of the art E, and angles respectively equal to 33 ° and 24 °, for the tires according to the invention II and 12. Concerning the hooping reinforcement, the non-elastic metal reinforcements of the two hooping layers, crossed from one layer to the next, form, with the circumferential direction XX ', an angle of between 6 ° and 8 ° , for the tire of the state of the art E and for the tires according to the invention II and 12.
    In the case studied, the tires respectively of the state of the art E and according to the invention II and 12 have treads comprising at least three cutouts or circumferential grooves, the cutouts having a width Wd at least equal to at 8 mm. The corresponding treads have an entableness rate of at least 12%.
    For the case studied in 40.00R57, the characteristics of the crown for the tire of the state of the art E taken as a reference and for the tires according to the invention II and 12 are presented in Table 1 below:
    Table 1 [0065] The tires of the state of the art and according to the invention have been subjected to measurements and tests, in particular to evaluate the thermal level of the crown, when the tire is subjected to pressure conditions, Recommended load and speed, and to quantify the breaking strength of the top, when the tire is subjected to aggression by indentors.
    As regards the thermal level, the temperature of the summit is measured near the axial ends of the crown reinforcement, which are generally the hot spots of the summit, with the aid of a temperature probe. The results of these thermal measurements, in terms of temperatures at the axial ends of the crown reinforcement, are presented in Table 2 below, in relative value with respect to the tire of the state of the art taken as a reference.
    To characterize the breaking strength of a tire crown reinforcement subjected to shocks, it is known to those skilled in the art to carry out tests consisting of rolling a tire, inflated to a recommended pressure and submitted to to a recommended load, on a cylindrical indenter, called polar, of diameter between 1 inch, or 25.4 mm, and 2.2 inches, or 55.9 mm, depending on the size of the tire, and a certain height. The breaking strength is characterized by the critical height of the polar, that is to say the maximum height of the polar resulting in a total rupture of the crown reinforcement, that is to say the breaking of all the Summit layers. The results of these stress tests, in terms of the maximum heights of a cylindrical polar of diameter equal to 2 inches, are presented in Table 2 below, with respect to the tire of the state of the art taken as a reference. as a base 100.
    Table 2 below presents the results of thermal performance and performance in resistance to aggression for tires of the state of the art E and according to the invention II and 12 studied:
    Table 2 [0069] The thermal level of the tires according to the invention II and 12 is respectively 10 ° and 9 ° less than the celpi of the tire of the state of the art E. The performance in resistance to attack from the top tires according to the invention II and 12 are respectively increased by 40% and 80% relative to that of the tire of the state of the art E.
    权利要求:
    Claims (19)
    [1" id="c-fr-0001]
    1 - Pneumatic tire (1) for a heavy vehicle. civil engineering type comprising a tread (2) and a crown reinforcement (3), radially inner to the tread (2): the tread (2), having a radial thickness Ηχ at least equal to 60 mm, comprising cutouts (21), having a width Wd and a radial depth Hd, and raised elements (22), separated by the cutouts (21),. o -the cutouts (21) whose width Wd is at most equal to 20% of the radial depth Hd and whose radial depth Hd is at least equal to 50% of the radial thickness Ηχ, said effective cutouts, having a cumulative length Ld, measured on a radially outer surface (23) of the tread (2), -the tread (2) having a surface laminating ratio TL, expressed in m / m 2, equal to the ratio between the cumulative length Ld effective cutouts (21) and area A of the radially outer surface (23) of the tread equal to 2nR | * W |; where Re is the outer radius of the tire, -the crown reinforcement (3) comprising a protective reinforcement (4), a working reinforcement (5) and a hooping reinforcement (6), -the protective armature ( 4), radially outermost, comprising at least two protective layers (41, 42), formed of elastic metal reinforcements, forming, with the circumferential direction (XX '), an angle of between 15 ° and 45 °, each layer protection device (41, 42) having a breaking strength R per unit of layer width, expressed in daN / m, Rmax being the maximum value of the rupture resistors R of the protective layers (41, 42), the armature working device (5) comprising at least two working layers (51, 52) formed of non-elastic metal reinforcements, crossed from one working layer to the next and forming, with a circumferential direction (XX ') of the tire, a angle between 15 ° and 45 °, the hooping armature (6), comprising at least one shrinking layer (61, 62), formed of metal reinforcements, forming, with the circumferential direction (XX '), an angle at most equal to 15 °, characterized in that the surface laminar TL ratio of the strip (2) is at least equal to 3 m / m 2 and that a coupling ratio X equal to the ratio between the maximum value Rmax of the breaking strengths R of the protective layers (41, 42) and the TL surface laminating of the tread (2) is at least equal to 30000 daN.
    [2" id="c-fr-0002]
    2- tire (1) for civil engineering heavy vehicle according to claim 1, wherein the coupling ratio C is at least equal to 40000 daN.
    [3" id="c-fr-0003]
    3 - Pneumatic tire (1) for heavy vehicle type civil engineering according to one of claims 1 or 2, wherein the coupling ratio C is at most equal to 120000 daN.
    [4" id="c-fr-0004]
    4 - Pneumatic tire (1) for heavy vehicle type civil engineering according to any one of claims 1 to 3, wherein the TL laminating rate of the tread (2) is at least equal to 3.5 m / m2.
    [5" id="c-fr-0005]
    5 - Pneumatic tire (1) for heavy vehicle type civil engineering according to any one of claims 1 to 4, wherein the TL laminating rate of the tread (2) is at most equal to 9 m / m2.
    [6" id="c-fr-0006]
    6 - Pneumatic tire (1) for heavy vehicle type civil engineering according to any one of claims 1 to 5, wherein the maximum value Rmax of the rupture resistors R protective layers (41, 42) is at least equal to 150000 daN / m, preferably at least 160000 daN / m.
    [7" id="c-fr-0007]
    7 - Pneumatic tire (1) for heavy vehicle type civil engineering according to any one of claims 1 to 6, wherein the breaking strength R of the most radially outer protective layer (41, 42) is equal to the value maximum Rmax of the rupture resistors R of the protective layers (41, 42).
    [8" id="c-fr-0008]
    8 - Pneumatic tire (1) for heavy vehicle type civil engineering according to any one of claims 1 to 7, wherein the breaking strength R of each protective layer (41, 42) is equal to the maximum value Rmax of the resistors with breaking R protective layers (41, 42).
    [9" id="c-fr-0009]
    9 - Pneumatic tire (1) for civil engineering heavy vehicle according to any of claims 1 to 8, wherein the minimum value Rmin of the rupture resistors R of the protective layers is such that the ratio Rm, n / TL is at least equal to 30000 daN.
    [10" id="c-fr-0010]
    10- tire (1) for heavy vehicle type civil engineering according to any one of claims 1 to 9, wherein the elastic metal reinforcements of the protective layers (41, 42) are multitoron cables, consisting of a single layer N strands, N being between 3 and 5, each strand being made of metal son.
    [11" id="c-fr-0011]
    11 - Pneumatic tire (1) for civil engineering heavy vehicle according to claim 10, wherein each strand, of formula (M + P), comprises an inner layer of M metal son and an outer layer of P wire wrapped around the inner layer.
    [12" id="c-fr-0012]
    12 - Pneumatic tire (1) for a heavy vehicle of civil engineering type according to claim 11, wherein the elastic metal reinforcements of the protective layers (41, 42) are multistrand cables of formula 4 * (3 + 8) * 0.35, consisting of a single layer of 4 strands, each strand comprising an inner layer of 3 metal wires and an outer layer of 8 metal wires wound around the inner layer, and each strand being made of metal wires with a diameter of 0.35 mm.
    [13" id="c-fr-0013]
    13 - Pneumatic tire (1) for civil engineering heavy vehicle according to claim 11, wherein the elastic metal reinforcements of the protective layers (41, 42) are multistrand cables of formula 4 * (4 + 9) * 0.26, consisting of a single layer of 4 strands, each strand comprising an inner layer of 4 metal wires and an outer layer of 9 metal wires wound around the inner layer, and each strand being made of metal wires with a diameter of 0.26 mm.
    [14" id="c-fr-0014]
    14 - Pneumatic tire (1) for civil engineering heavy vehicle according to claim 10, wherein each strand, of formula (M + N + P), comprises an intermediate layer of N metal son wound around the inner layer of M son metallic, the outer layer of P metal wires being wound around the intermediate layer of N metal wires.
    [15" id="c-fr-0015]
    15 - Pneumatic tire (1) for civil engineering heavy vehicle according to one of claims 11 or 14, wherein the outer layer of P metal son is unsaturated.
    [16" id="c-fr-0016]
    16- tire (1) for heavy vehicle type civil engineering according to any one of claims 10 to 15, wherein the diameter of the constituent son of each strand is at least equal to 0.22 mm, preferably at least equal to 0.26 mm .
    [17" id="c-fr-0017]
    17 - Pneumatic tire (1) for heavy vehicle type civil engineering according to any one of claims 10 to 16, wherein the elastic metal reinforcements of the protective layers (41, 42) have, in the air permeability test, an average air flow rate of less than 30 cm3 / min.
    [18" id="c-fr-0018]
    18- tire (1) for a heavy vehicle of civil engineering type according to any one of claims 10 to 17, wherein the elastic metal reinforcements of the protective layers (41, 42) are distributed at an average pitch of between 3.5 mm and 5 mm.
    [19" id="c-fr-0019]
    19- Pneumatic tire (1) for heavy vehicle type civil engineering according to any one of claims 1 to 18, the set of cutouts (21) having a total volume Vd and all of the raised elements (22) having a total volume Vr, the tread (2) having a volume notching rate TEV, expressed in%, equal to the ratio between the total volume Vd of the cutouts (21) and the sum of the total volume Vd of the cutouts (21) and of the total volume of the raised elements (22) in which the level of volume notching TEV of the tread (2) is at least 12%, preferably at least 14%.
    类似技术:
    公开号 | 公开日 | 专利标题
    EP2855763B1|2017-07-12|Method for producing a two-layer multi-strand metal cable
    EP2855764A1|2015-04-08|Two-layer multi-strand metal cable
    EP3390107B1|2020-09-09|Tyre crown for heavy goods vehicle of the civil engineering type
    WO2015090920A1|2015-06-25|Two-layer multi-strand metal cable
    EP3541638B1|2020-08-12|Tyre crown for a heavy duty civil engineering vehicle
    EP3390101B1|2020-07-29|Tire having improved wear and rolling resistance properties
    EP3019344B1|2019-10-23|Air tyre having a softened carcass reinforcement
    EP3019343B1|2017-08-30|Tyre comprising variable thicknesses of the rubber mixtures inside the carcass reinforcement
    WO2015090921A1|2015-06-25|Two-layer multi-strand metal cable
    EP3344474B1|2020-11-04|Pneumatic tire comprising low-carbon carcass reinforcing cords and having reduced thicknesses of rubber mixtures
    EP3559338A1|2019-10-30|Two-layer multi-strand cable with improved penetrability
    WO2018134488A1|2018-07-26|Tyre sidewall for a heavy duty civil engineering vehicle
    EP3077221B1|2018-07-25|Tyre comprising carcass reinforcement cords havinglow permeability and variable rubber mixture thicknesses
    EP3019345B1|2019-07-03|Air tyre comprising carcass reinforcement cords with low permeability
    WO2019243691A1|2019-12-26|Double-layer multi-strand cord with improved penetrability
    EP3390102B1|2020-11-18|Tire having improved wear and rolling resistance properties
    EP3390097B1|2020-11-18|Tyre having improved wear and rolling resistance properties
    EP3523140B1|2021-05-19|Tyre tread for a heavy civil-engineering vehicle
    EP3390096B1|2020-09-09|Tire having improved wear properties and improved rolling resistance
    EP3390098B1|2020-11-18|Tyre having improved properties of wear and rolling resistance
    WO2019243692A1|2019-12-26|Double-layer multi-strand cord with improved penetrability
    同族专利:
    公开号 | 公开日
    US20180370292A1|2018-12-27|
    EP3390107A1|2018-10-24|
    FR3044967B1|2017-12-22|
    WO2017103478A1|2017-06-22|
    BR112018011886A2|2018-11-27|
    JP2018537349A|2018-12-20|
    CN108698449A|2018-10-23|
    CN108698449B|2019-10-25|
    EP3390107B1|2020-09-09|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JPH11348509A|1998-04-10|1999-12-21|Bridgestone Corp|Heavy load resistant pneumatic radial tire|
    WO2015140139A1|2014-03-18|2015-09-24|Compagnie Generale Des Etablissements Michelin|Civil engineering vehicle tyre with improved endurance|
    WO2015162174A1|2014-04-22|2015-10-29|Compagnie Generale Des Etablissements Michelin|Tyre for heavy industrial vehicle|
    DE19753819B4|1997-12-04|2004-04-01|Continental Aktiengesellschaft|Tread pattern of a winter tire|
    FR2824295A1|2001-05-03|2002-11-08|Michelin Soc Tech|SUMMIT FRAME FOR CIVIL ENGINEERED TIRES|
    AU2003282064A1|2003-10-31|2005-06-08|Pirelli Pneumatici S.P.A.|High-performance tyre for vehicle wheels|
    WO2006013758A1|2004-08-03|2006-02-09|Bridgestone Corporation|Pneumatic tire|
    BRPI0607219B1|2005-01-28|2018-11-06|Bridgestone Corp|radial tire for a construction vehicle|
    DE602005017679D1|2005-12-23|2009-12-24|Pirelli|AIR TIRES FOR HEAVY VEHICLES|
    FR2900367B1|2006-04-26|2008-07-04|Michelin Soc Tech|PNEUMATIC FOR HANDLING VEHICLE|
    JP2009126314A|2007-11-22|2009-06-11|Yokohama Rubber Co Ltd:The|Pneumatic tire|
    FR2943950B1|2009-04-07|2011-04-15|Michelin Soc Tech|TIRE FOR HEAVY VEHICLES COMPRISING A CIRCUMFERENTIAL ELEMENT LAYER.|
    FR2947575B1|2009-07-03|2011-08-19|Michelin Soc Tech|CABLE MULTITORONS WHOSE ELEMENTARY TORONES ARE CABLES WITH TWO LAYERS GOMMES IN SITU.|
    FR2959517B1|2010-04-28|2012-09-21|Michelin Soc Tech|ELASTIC MULTITOROUS METAL CABLE WITH HIGH PERMEABILITY.|
    FR2962453B1|2010-05-20|2012-09-21|Michelin Soc Tech|THREE-LAYER METAL CABLE, GUM IN SITU BY UNSATURATED THERMOPLASTIC ELASTOMER|
    CN103180152B|2010-10-29|2016-03-09|米其林集团总公司|There is the tire protector of multiple wearing layer|
    US20130048169A1|2011-08-30|2013-02-28|Boris Erceg|Pneumatic tire with dual tread cap|
    FR2990963B1|2012-05-25|2014-12-05|Michelin & Cie|MULTI-TONE METAL CABLE WITH TWO LAYERS.|
    FR2995822B1|2012-09-26|2014-09-12|Michelin & Cie|PNEUMATIC TOP FOR A HEAVY VEHICLE OF GENIE CIVIL TYPE|
    CN105142933B|2013-04-30|2018-07-13|米其林集团总公司|The manufacturing method of improved tyre surface and retreads|WO2019058053A1|2017-09-22|2019-03-28|Compagnie Generale Des Etablissements Michelin|Crown reinforcement for a tyre for a heavy vehicle of construction plant type|
    CN112004691A|2018-04-17|2020-11-27|米其林集团总公司|Protective reinforcement comprising different layers for a pneumatic tire for a heavy civil engineering vehicle|
    WO2019202240A1|2018-04-17|2019-10-24|Compagnie Generale Des Etablissements Michelin|Protective reinforcement for a tyre for a heavy civil-engineering vehicle|
    法律状态:
    2016-12-22| PLFP| Fee payment|Year of fee payment: 2 |
    2017-06-16| PLSC| Publication of the preliminary search report|Effective date: 20170616 |
    2017-12-21| PLFP| Fee payment|Year of fee payment: 3 |
    2019-09-27| ST| Notification of lapse|Effective date: 20190906 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1562374A|FR3044967B1|2015-12-15|2015-12-15|PNEUMATIC TOP FOR A HEAVY VEHICLE OF GENIE CIVIL TYPE|FR1562374A| FR3044967B1|2015-12-15|2015-12-15|PNEUMATIC TOP FOR A HEAVY VEHICLE OF GENIE CIVIL TYPE|
    EP16825515.6A| EP3390107B1|2015-12-15|2016-12-14|Tyre crown for heavy goods vehicle of the civil engineering type|
    BR112018011886-9A| BR112018011886B1|2015-12-15|2016-12-14|TOP OF TIRE FOR HEAVY CIVIL ENGINEERING VEHICLE|
    US16/062,474| US20180370292A1|2015-12-15|2016-12-14|Tire Crown For Heavy Goods Vehicle Of The Civil Engineering Type|
    PCT/FR2016/053427| WO2017103478A1|2015-12-15|2016-12-14|Tyre crown for heavy goods vehicle of the civil engineering type|
    JP2018529569A| JP2018537349A|2015-12-15|2016-12-14|Tire crowns for civil engineering heavy vehicles|
    CN201680071753.9A| CN108698449B|2015-12-15|2016-12-14|Tyre crown for civil engineering type heavy vehicle|
    [返回顶部]