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EP1047565A1 - Tyre bead with circumferential reinforcing elements - Google Patents

Tyre bead with circumferential reinforcing elements

Info

Publication number
EP1047565A1
EP1047565A1 EP98966350A EP98966350A EP1047565A1 EP 1047565 A1 EP1047565 A1 EP 1047565A1 EP 98966350 A EP98966350 A EP 98966350A EP 98966350 A EP98966350 A EP 98966350A EP 1047565 A1 EP1047565 A1 EP 1047565A1
Authority
EP
European Patent Office
Prior art keywords
reinforcement
bead
radially
axially
rod
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98966350A
Other languages
German (de)
French (fr)
Inventor
Pascal Auxerre
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Compagnie Generale des Etablissements Michelin SCA
Original Assignee
Compagnie Generale des Etablissements Michelin SCA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Compagnie Generale des Etablissements Michelin SCA filed Critical Compagnie Generale des Etablissements Michelin SCA
Publication of EP1047565A1 publication Critical patent/EP1047565A1/en
Withdrawn legal-status Critical Current

Links

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
    • B60C15/00—Tyre beads, e.g. ply turn-up or overlap
    • B60C15/0009—Tyre beads, e.g. ply turn-up or overlap features of the carcass terminal portion
    • B60C15/0081—Tyre beads, e.g. ply turn-up or overlap features of the carcass terminal portion the carcass plies folded around or between more than one bead core
    • 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
    • B60C15/00—Tyre beads, e.g. ply turn-up or overlap
    • 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
    • B60C15/00—Tyre beads, e.g. ply turn-up or overlap
    • B60C15/04—Bead cores
    • B60C15/05—Bead cores multiple, i.e. with two or more cores in each bead
    • 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
    • B60C15/00—Tyre beads, e.g. ply turn-up or overlap
    • B60C15/06—Flipper strips, fillers, or chafing strips and reinforcing layers for the construction of the bead
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T152/00—Resilient tires and wheels
    • Y10T152/10—Tires, resilient
    • Y10T152/10495—Pneumatic tire or inner tube
    • Y10T152/10819—Characterized by the structure of the bead portion of the tire
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T152/00—Resilient tires and wheels
    • Y10T152/10—Tires, resilient
    • Y10T152/10495—Pneumatic tire or inner tube
    • Y10T152/10819—Characterized by the structure of the bead portion of the tire
    • Y10T152/10828—Chafer or sealing strips

Definitions

  • the present invention relates to a tire with a radial carcass reinforcement intended to carry heavy loads, and more particularly to a tire of the "Heavy Duty" type, intended to equip vehicles such as, for example, trucks, road tractors, buses, trailers and others, and more particularly the new structure for reinforcing the beads of said tires.
  • a tire of the type under consideration comprises a carcass reinforcement formed of at least one ply of metal cables, anchored in each bead to a bead, by forming a reversal.
  • the carcass reinforcement is radially surmounted by a crown reinforcement, composed of at least two plies of metal cables, crossed from one ply to the next, forming angles of between 10 ° and 45 ° with the circumferential direction.
  • Carcass reinforcement upturns are generally reinforced by at least one bead reinforcement ply formed of metal cables oriented at a small angle relative to the circumferential direction, generally between 10 ° and 30 °.
  • the bead reinforcement ply is generally located axially on the outside, along the carcass reinforcement upturn, with a radially upper end situated above or below the radially upper end of the carcass reinforcement upturn.
  • the radially lower end of such a ply of reinforcement it is generally located under a straight line parallel to the axis of rotation and passing approximately through the center of gravity of the meridian section of the anchoring rod of the carcass reinforcement.
  • the aim of the known solution is to avoid the de-shedding of the cables of the inversion of the carcass reinforcement, as well as to minimize the radial and circumferential deformations undergone by the end of the said inversion, and by the outer rubber layer covering the bead and ensuring the connection with the rim.
  • the carcass reinforcement of a radial tire mounted on its service rim and inflated to the recommended pressure, has in a sidewall a regularly convex meridian profile between approximately the zones of connection on the one hand with the meridian profile of the crown reinforcement and on the other hand with the bead.
  • said reinforcement has in the bead a meridian profile either substantially straight or curved in the opposite direction to the curvature in the sides, c that is to say substantially parallel to the curvature of the edges of rim from an inflection point located approximately radially at the radially upper end of the bead reinforcement ply, placed along the carcass reinforcement upturn.
  • Such an arrangement associating two rods in a bead with a meridian profile having an inflection point in the region of the bead significantly improves the endurance of the beads in the case of rolling on a heated rim, but becomes however insufficient, in in the case of driving where the supported loads become higher, or the inflation pressures lower, than the recommended loads and pressures, and more particularly when the ratio of the height on the rim H to the maximum axial width S of the tire becomes less than 0 , 8.
  • said tire comprises at least one frame of radial carcass, formed of at least one ply of inextensible reinforcing elements, anchored in each bead B with at least two rods close to each other, turned around the first and then wrapped around the second to form an inversion, and it is characterized in that, seen in meridian section, an additional reinforcement reinforcement, formed of at least one ply of circumferential reinforcement elements is placed along the carcass reinforcement, at least axially inside, in the bead region where the outline of the meridian profile of said carcass reinforcement changes curvature to become rectilinear or concave up to the point of tangency T with the coating layer almost circular of the first anchor rod, said reinforcing reinforcement having its radially lower end radially below the straight line D ', parallel to the axis of rotation and passing through the
  • the additional reinforcement preferably has its radially upper end situated at a radial distance from the straight line D, between an amount equal to the radial half-distance between the straight lines D and D "increased by the radial half-distance between the straight lines D and D 'and an amount equal to the radial half-distance between the lines D and D "minus the radial half-distance between the lines D and D', the line D" being the line of greatest axial width.
  • the line D "of greatest axial width is, by definition, the line parallel to the axis of rotation and passing through the point of the meridian profile carcass reinforcement corresponding to the point of highest grade axial width when the tire is mounted on its service rim and inflated to the recommended pressure and not loaded.
  • the elements of the additional reinforcement are said to be circumferential if the angle they form with the circumferential direction is between + 5 ° and - 5 °.
  • Reinforcement elements are said to be contiguous if, in the direction perpendicular to said elements, the distance separating two adjacent elements is reduced as much as possible.
  • Patent FR 750 726 of the applicant teaches the bonding of carcass reinforcement plies to auxiliary reinforcements, each formed from wire wound in a spiral and consequently having a notable flexibility in the transverse direction. Said bonding is carried out so that two carcass reinforcement plies enclose an auxiliary reinforcement, said clamping being effected in the absence of rod and carcass reinforcement flipping.
  • Patent FR 1,169,474 also teaches to remove the rod usually used by small plies of metal wires or cables inclined on the attachment parallel, the angle of inclination being able to descend to 5 °, the ply (s) (s) of carcass reinforcement being returned or not.
  • Patent FR 1 234 995 provides for the replacement of the usually oblique reinforcement elements of the bead reinforcement ply (s) intended to reduce the movements of the attachment against the rim flange, by circumferential elements. , the reinforcing reinforcement being able to be disposed between the main part of the carcass reinforcement and the inversion of said reinforcement, or axially outside said carcass reinforcement inversion.
  • Document FR 2 055 988 describes a certain number of possible applications of a bead reinforcement reinforcement with circumferential elements, in particular the use of such a reinforcement instead of the usual reinforcement with oblique elements arranged axially. outside the carcass reinforcement upturn.
  • the carcass reinforcement so as to reduce the volume of the beads as much as possible, is advantageously formed of reinforcing elements made of textile material, which makes it possible to easily carry out the armature windings around the rods.
  • a preferred solution of the invention then consists in providing said tire with a carcass reinforcement in three parts: a first part of metallic reinforcing elements passing at least under the crown reinforcement and in the sidewalls, and two other parts , formed of textile reinforcing elements, turned over and wound around the two anchor rods of each bead.
  • edges of the metal part, part which may or may not be turned around the anchor rods have, with the axially inner edges of the textile parts, a common length of overlap, at least situated in the region where the additional reinforcement is located. circumferential reinforcing elements.
  • the endurance of the beads in accordance with the invention, can also be improved by a thinning of said beads, by giving the carcass reinforcement anchored to two rods in a bead a meridian profile having no change in curvature in the region. beads.
  • Said meridian profile is then characterized in that, seen in meridian section, its layout, between the point A of greatest axial width and the point of tangency T with the almost circular coating layer of the first anchor rod, is convex and circular over its entire length, the center of curvature being located on the straight line D "of greater axial width, such as the thickness ⁇ of the bead B, measured on a perpendicular to said meridian profile at a point C of height hc, between 30 and 40 mm, measured with respect to the bead base Y Y ', is between 2 and 2.5 times the thickness e of the sidewall measured on the straight line D "of greater axial width.
  • rods of the "package" type with polygonal section that is to say rods obtained by winding on a form of a metal wire leading to several layers of different widths.
  • the above rod types also allow less size due to the shape of their cross sections and the possible reduction of said sections, respectively of the order of 30% and 50% for each, which leads, in relation to the application of the invention, to rods with more bulky rectangular wires, to have a thinner bead thickness.
  • the bead reinforcement thus described can be produced separately by spiral winding on a horizontal support of suitable shape, and then transferred to the unvulcanized tire blank.
  • the manufacture of such a tire will however advantageously be facilitated by the use, as reinforcing elements, of sections or of sets or groups of sections of cables, of circumferential length between 0.2 and 0.4 times the circumferential length of the reinforcement ply, which allows the fitting of the bead reinforcement reinforcement on the drum for making the raw carcass reinforcement blank and the toroidal shaping of said blank without major difficulties, and said average length being measured when laid on said construction drum.
  • the interstices or circumferential cuts between cut elements are preferably offset with respect to each other.
  • FIG. 1 schematically represents a tire structure, known from the state of the art
  • FIG. 2 schematically represents and in an enlarged view a first variant of a bead in accordance with the invention, in its normal version
  • FIG. 3 schematically represents a second variant of bead according to the invention, the rods being braided rods and the bead being thinned,
  • FIG. 4 schematically shows a variant of the invention with a carcass reinforcement in three parts.
  • the tire P of the prior art shown in FIG. 1, is a tire of dimension 205/75 R 17.5, intended to be mounted on a rim comprising rim seats J inclined at 15 °.
  • Said tire comprises a tread (4) joined to two beads B by means of two sidewalls (5).
  • Each bead B is reinforced by a rod (1) formed by winding on a suitable form a wire with a quadrilateral section until several rows of radially juxtaposed wires are obtained.
  • a carcass reinforcement (2) composed of a single ply of aromatic polyamide cables.
  • the carcass reinforcement (2) has, seen in meridian section, a meridian profile, between point A of greater axial width and the point of tangency T of said profile with the almost circular coating layer (10) of the rod (1) (it is written almost circular because the coating layer hardly ever has a perfectly circular transverse shape), presenting two curvatures: the profile is convex of the point A at point J of inflection situated radially above the rod, and it is concave from said point of inflection to point T of tangency.
  • the carcass reinforcement (2) is anchored by an inversion (20) around the layer (10) of rubber mixture which covers the rod (1), the radial distance h, separating the radially upper end of said reversal (20) of the straight line YY '(parallel to the axis of rotation and defining the nominal diameter of the bead, which is also, in this case, that of the rim) and being equal, in the studied example of the tire dimension 205/75 R 17.5, at 25 mm. Between the carcass reinforcement (2) and its upturn (20), radially above the rod (1), is disposed a rod stuffing (71) in a rubber mixture of generally high Shore hardness.
  • a reinforcement ply (6) formed of inextensible metallic cables weakly oriented relative to the circumferential direction, and the radially upper end of which is further from the axis of rotation. that the upper end of the carcass reinforcement upturn (20) (2).
  • Said ply (6) is on the one hand, separated from the carcass reinforcement (2) and the rod stuffing (71) by a second filling stuffing (72), and on the other hand, from the rubbery protective mixture ( 8) which surrounds the bead, by a third stuffing (73).
  • the bead B of the tire of size 205/75 R 17.5, in accordance with the invention and shown in FIG. 2, is reinforced by two bead wires (11) and (12), each of said bead wires with rectangular wires, that is to say - said formed by the winding on a suitable form of a wire of rectangular section until several rows of radially juxtaposed wires are obtained, being coated in a rubber mixture (110) (120) with high modulus elongation.
  • the straight line joining the two centers of gravity of the cross sections of rods (11) and (12) makes with the axis of rotation an angle ⁇ , open axially and radially outwards, equal to 26 °.
  • the carcass reinforcement (2) is formed, in the case described, of a single ply (2) of aromatic polyamide, and its anchoring is done by means of two rods (11) and (12)
  • the meridian profile of said reinforcement (2) is, as defined above, tangent in T to the quasi-circular coating layer (110) of the first rod (11), axially and radially innermost, to then wind around of said rod (11) going radially from the outside to the inside and axially from the inside to the outside, then extend to the second rod (12), and wrap around said rod ( 12) by going radially from the inside to the outside and axially from the outside to the inside and finally radially from the outside to the inside to join the first rod (11) axially outside and have its end radially under said first rod (11).
  • the arrangement of the rubber jams between the various reinforcing elements is then modified as follows: axially and radially outside the axially inner rod (11) is a first jam (71), axially and radially outside the axially outer rod is a second padding (72), while radially and axially inside the axially outer rod (12) is a third padding (73).
  • Said arrangement can be modified in the sense that the complex formed by the axially outer rod (12) surrounded by the coating (120) and the stuffing (73) can be replaced by a single stuffing of rubber (73). It is then advantageous for the secant modulus of elasticity to the tension of said single padding to be high: measured at 1% relative elongation, this modulus is preferably at least equal to lO MPa.
  • the meridian profile of the carcass reinforcement (2) is continuously convex between the point A of greatest axial width and the point of tangency T to the covering (110) of the rod (11) axially the most interior without showing an inflection point J.
  • the convexity of said profile, of single radius R, the center of curvature of which is situated on the straight line D "of greater axial width, is such that the thickness ⁇ of the bead B, measured on a perpendicular to said meridian profile at a point C of height hc, equal to 34 mm, measured with respect to the bead base YY ', either equal to 19 mm, or 2.5 times the thickness e of the flank measured on the straight line D "of greatest axial width, then that the thickness, measured under the same conditions, of the bead of FIG. 1 is equal to 22 mm.
  • the bead is also characterized by the presence of a reinforcing reinforcement (6) composed of a bead reinforcing ply (61), formed of metallic circumferential elements of steel which are cut metal cables 19 x 28, the length said elements or sections of cables being equal to a quarter of the circumferential length of said ply (61), measured at its laying radius before conformation of the unvulcanized blank of the carcass reinforcement, said ply (61) being placed axially at inside the carcass reinforcement (2) and not axially outside the reversal (20) of the carcass reinforcement (2).
  • the spaces between the ends of elements before shaping the blank have a small amplitude (3 mm) and are offset circumferentially between them.
  • the radially lower end of the ply (61) is distant from the axis of rotation of the tire by an amount equal to 227 mm, that is to say between the distance of 223 mm separating from the axis of rotation the straight line D passing through the point, of the almost circular coating layer (110) of the first anchor rod (10) closest to the axis of rotation and the distance of 233 mm separating from the axis of rotation the straight line D 'passing through the point of the coating layer (110) furthest from said axis of rotation.
  • the radially upper end it is located radially, in the case described, at a distance r e from the axis of rotation equal to 255 mm, an amount which is between an amount of 265 mm, equal to half sum 260 mm of the respective distances to the axis of rotation of the straight lines D and D "(297 + 223/2), the straight line D" of greatest axial width passing through the point A being 297 mm from the axis of rotation ) increased by the radial half-distance of 5 mm between the straight lines D and D '(233-223/2), and an amount of 255 mm, equal to the half-sum 260 mm of the respective distances to the axis of rotation lines D and D "minus the radial half-distance of 5 mm between lines D and D '.
  • Bead B shown in FIG. 3, has, seen in meridian section, a meridian profile of carcass reinforcement (2) which, as in the case of FIG. 2, between point A of greater axial width and the point of tangency T of said profile with the circle circumscribed to the coating layer (110) of the first rod (11) is continuously convex, without inflection point J in the region of the bead. Said bead in FIG. 3 differs from that in FIG.
  • the first rod (11) axially and radially innermost is a rod of the "braided" type which, in area of cross section equal to the cross-sectional area of a rectangular wire rod, allows a generally smaller overall size, and secondly by the fact that the complex formed by the axially outer rod (12) and the rubber profile (73 ) is replaced by a single padding (73), which accentuates the thinning of the bead and the reduction in weight of the tire.
  • the above arrangement makes it possible to obtain a bead thickness ⁇ , measured on a perpendicular to said meridian profile at a point C of height h c , equal to 30 mm, measured relative to the bead base YY ', ie equal to 17 mm, or 2.2 times the thickness e of the sidewall measured on the straight line D "of greater axial width.
  • the bead reinforcement ply (6) composed of circumferential elements, is, as in the case shown on Figure 2, placed axially inside the carcass reinforcement (2) and not axially outside the upturn (20) of the carcass reinforcement (2).
  • the bead B in FIG. 4 differs from that in FIG. 3 only in that the carcass reinforcement (2) of the tire in question is composed of a first part (21) formed of metallic cables, and of two parts ( 22) formed of textile cables.
  • the first part (21) has, on the one hand a tracing of a meridian profile passing under the summit (not shown) and in the sides, and on the other hand two edges (210) partially turned around the complex formed by the rod d anchor (11) and the profile (73).
  • Each second part has an axially inner edge (220), which has an edge (210) of the first part with a common length of overlap, and such that the radially upper end of said edge is radially inside the end radially upper of the additional reinforcement ply (61).
  • Said second part is turned around the rod (11), to then wrap around the single stuffing (73) and have a second edge located radially under the rod (11).
  • Pc tires comprising beads of normal thickness, two anchor rods in each bead and an additional bead reinforcement, with circumferential elements and located axially inside the carcass reinforcement, have reached the following mileage: 61,000 km when driving with overload and 29,000 km when driving on a heated rim.

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

Abstract

The invention concerns a tyre comprising at least a radial body ply (2), anchored in each tyre bead (B) to two bead wires (11) and (12) to form a turn-up (20), characterised in that, viewed in meridian cross-section, a supplementary reinforcement (6), formed by at least one ply (61) of circumferential reinforcing elements, is placed, at least axially inside, along the radial body ply (2) in the tyre bead (B) zone.

Description

BOURRELET DE PNEUMATIQUE AVEC ELEMENTS DE RENFORT CIRCONFERENTIELS TIRE SADDLE WITH CIRCUMFERENTIAL REINFORCEMENT ELEMENTS
La présente invention concerne un pneumatique à armature de carcasse radiale destiné à porter de lourdes charges, et plus particulièrement un pneumatique de type "Poids Lourds", destiné à équiper des véhicules tels que, par exemple, les camions, tracteurs routiers, autobus, remorques et autres, et plus particulièrement la nouvelle structure de renforcement des bourrelets desdits pneumatiques.The present invention relates to a tire with a radial carcass reinforcement intended to carry heavy loads, and more particularly to a tire of the "Heavy Duty" type, intended to equip vehicles such as, for example, trucks, road tractors, buses, trailers and others, and more particularly the new structure for reinforcing the beads of said tires.
En général, un pneumatique du type considéré comprend une armature de carcasse formée d'au moins une nappe de câbles métalliques, ancrée dans chaque bourrelet à une tringle, en formant un retournement. L'armature de carcasse est radialement surmontée d'une armature de sommet, composée d'au moins deux nappes de câbles métalliques, croisés d'une nappe à la suivante en formant avec la direction circonférentielle des angles compris entre 10° et 45°. Les retournements d'armature de carcasse sont généralement renforcés par au moins une nappe de renforcement de bourrelet formée de câbles métalliques orientés à un faible angle par rapport à la direction circonférentielle, compris généralement entre 10° et 30°.In general, a tire of the type under consideration comprises a carcass reinforcement formed of at least one ply of metal cables, anchored in each bead to a bead, by forming a reversal. The carcass reinforcement is radially surmounted by a crown reinforcement, composed of at least two plies of metal cables, crossed from one ply to the next, forming angles of between 10 ° and 45 ° with the circumferential direction. Carcass reinforcement upturns are generally reinforced by at least one bead reinforcement ply formed of metal cables oriented at a small angle relative to the circumferential direction, generally between 10 ° and 30 °.
La nappe de renforcement de bourrelet est généralement située axialement à l'extérieur, le long du retournement d'armature de carcasse, avec une extrémité radialement supérieure située au dessus ou au dessous de l'extrémité radialement supérieure du retournement d'armature de carcasse. Quant à l'extrémité radialement inférieure d'une telle nappe de renforcement, elle est généralement située sous une droite parallèle à l'axe de rotation et passant approximativement par le centre de gravité de la section méridienne de la tringle d'ancrage de l'armature de carcasse.The bead reinforcement ply is generally located axially on the outside, along the carcass reinforcement upturn, with a radially upper end situated above or below the radially upper end of the carcass reinforcement upturn. As for the radially lower end of such a ply of reinforcement, it is generally located under a straight line parallel to the axis of rotation and passing approximately through the center of gravity of the meridian section of the anchoring rod of the carcass reinforcement.
La solution connue a pour but d'éviter la déradiahsation des câbles du retournement de l'armature de carcasse, ainsi que de minimiser les déformations radiales et circonférentielles subies par l'extrémité dudit retournement, et par la couche de caoutchouc extérieure recouvrant le bourrelet et assurant la liaison avec la jante.The aim of the known solution is to avoid the de-shedding of the cables of the inversion of the carcass reinforcement, as well as to minimize the radial and circumferential deformations undergone by the end of the said inversion, and by the outer rubber layer covering the bead and ensuring the connection with the rim.
La durée de vie des pneumatiques "Poids-Lourds", du fait des progrès accomplis, du fait que certains roulages sont rendus moins pénalisants en ce qui concerne l'usure de la bande de roulement, est devenue telle qu'il est encore nécessaire d'améliorer l'endurance des bourrelets. Ladite amélioration doit porter sur la dégradation des couches de caoutchouc au niveau des extrémités de retournement d'armature de carcasse et extrémités radialement extérieures des nappes de renforcement de bourrelets. Plus particulièrement dans le cas de pneumatiques soumis à des roulages prolongés, roulages induisant souvent une température élevée des bourrelets, du fait des températures atteintes par les jantes de montage, les mélanges de caoutchouc en contact avec la jante sont alors sujets à une diminution de leurs rigidités, ainsi qu'à une oxydation plus ou moins lente, d'où une tendance très marquée de l'armature de carcasse à se dérouler autour de la tringle sous l'effet de la pression de gonflage intérieure, malgré la présence d'une ou plusieurs nappes de renforcement de bourrelets. Prennent alors naissance des mouvements de tringle, des déformations de cisaillement à toutes les extrémités de nappes, pour aboutir à la destruction du bourrelet. Ladite amélioration doit aussi, et principalement, porter sur cette deuxième possibilité de dégradation.The lifespan of "Heavy Duty" tires, due to the progress made, the fact that certain runs are made less penalizing as regards the wear of the tread, has become such that it is still necessary to '' improve the endurance of the beads. Said improvement must relate to the degradation of the rubber layers at the ends of the carcass reinforcement upturn and radially outer ends of the bead reinforcement plies. More particularly in the case of tires subjected to prolonged running, rolling often inducing a high temperature of the beads, due to the temperatures reached by the mounting rims, the rubber mixtures in contact with the rim are then subject to a reduction in their rigidities, as well as more or less slow oxidation, hence a very marked tendency for the carcass reinforcement to unwind around the bead wire under the effect of the internal inflation pressure, despite the presence of a or several reinforcing plies of beads. Rod movements then arise, shear deformations at all ends of the plies, to lead to the destruction of the bead. Said improvement must also, and mainly, relate to this second possibility of degradation.
Le brevet US 3 301 303 revendique, pour améliorer l'endurance de la zone des bourrelets d'un pneumatique portant des fortes charges, une armature de carcasse enroulée suivant un tracé précis autour de deux tringles de bourrelets pratiquement axialement adjacentes : l'armature de carcasse est d'abord ancrée par retournement autour de la tringle axialement la plus à l'intérieur en allant radialement de l'extérieur à l'intérieur, puis axialement de l'intérieur à l'extérieur, pour passer ensuite radialement au dessous de la deuxième tringle, disposée axialement à l'extérieur, pour s'enrouler autour de ladite deuxième tringle en allant radialement de l'intérieur à l'extérieur puis axialement de l'extérieur à l'intérieur pour former un retournement revenant radialement sous la première tringle et s'enroulant éventuellement autour de ladite tringle pour être disposé ensuite le long de la face axialement extérieure de la nappe de carcasse.US Pat. No. 3,301,303 claims, in order to improve the endurance of the bead zone of a tire carrying heavy loads, a carcass reinforcement wound in a precise path around two bead rods practically axially adjacent: the reinforcement of carcass is first anchored by turning around the rod axially innermost by going radially from the outside to the inside, then axially from the inside to the outside, then passing radially below the second rod, arranged axially outside, to wrap around said second rod going radially from the inside to the outside then axially from the outside to the inside to form a reversal returning radially under the first rod and optionally winding around said rod to be then placed along the axially outer face of the carcass ply.
L'armature de carcasse d'un pneumatique radial, monté sur sa jante de service et gonflé à la pression recommandée, a dans un flanc un profil méridien régulièrement convexe entre approximativement les zones de raccordement d'une part avec le profil méridien de l'armature de sommet et d'autre part avec le bourrelet. En particulier, à partir du rayon où l'armature de carcasse subit l'influence des nappes de renforcement de bourrelets, ladite armature possède dans le bourrelet un profil méridien soit sensiblement rectiligne soit incurvé dans le sens opposé à la courbure dans les flancs, c'est-à-dire sensiblement parallèle à la courbure des rebords de jante à partir d'un point d'inflexion situé radialement approximativement au niveau de l'extrémité radialement supérieure de la nappe de renforcement de bourrelet, placée le long du retournement d'armature de carcasse.The carcass reinforcement of a radial tire, mounted on its service rim and inflated to the recommended pressure, has in a sidewall a regularly convex meridian profile between approximately the zones of connection on the one hand with the meridian profile of the crown reinforcement and on the other hand with the bead. In particular, from the radius where the carcass reinforcement is influenced by the bead reinforcement plies, said reinforcement has in the bead a meridian profile either substantially straight or curved in the opposite direction to the curvature in the sides, c that is to say substantially parallel to the curvature of the edges of rim from an inflection point located approximately radially at the radially upper end of the bead reinforcement ply, placed along the carcass reinforcement upturn.
Une telle disposition associant deux tringles dans un bourrelet à un profil méridien présentant un point d'inflexion dans la région du bourrelet, améliore de manière importante l'endurance des bourrelets dans le cas de roulage sur une jante chauffante, mais devient cependant insuffisante, dans les cas d'un roulage où les charges supportées deviennent supérieures, ou les pressions de gonflage inférieures, aux charges et pressions recommandées, et plus particulièrement lorsque le rapport de la hauteur sur jante H sur la largeur axiale maximale S du pneumatique devient inférieur à 0,8.Such an arrangement associating two rods in a bead with a meridian profile having an inflection point in the region of the bead, significantly improves the endurance of the beads in the case of rolling on a heated rim, but becomes however insufficient, in in the case of driving where the supported loads become higher, or the inflation pressures lower, than the recommended loads and pressures, and more particularly when the ratio of the height on the rim H to the maximum axial width S of the tire becomes less than 0 , 8.
Les recherches de la demanderesse ont permis d'arriver à la conclusion que le profil méridien d'armature des carcasse dans la région du changement de courbure dans le bourrelet devait être renforcé par au moins une armature de renforcement de bourrelet.The Applicant's research has led to the conclusion that the meridian profile of carcass reinforcement in the region of the change in curvature in the bead must be reinforced by at least one bead reinforcing reinforcement.
Afin d'améliorer l'endurance des bourrelets d'un pneumatique à rapport de forme H/S inférieur à 0,8, destiné à équiper un véhicule portant de lourdes charges, ledit pneumatique, conforme à l'invention, comprend au moins une armature de carcasse radiale, formée d'au moins une nappe d'éléments de renforcement inextensibles, ancrée dans chaque bourrelet B à au moins deux tringles proches l'une de l'autre, retournée autour de la première et ensuite enroulée autour de la deuxième pour former un retournement, et il est caractérisé en ce que, vue en section méridienne, une armature additionnelle de renforcement, formée d'au moins une nappe d'éléments de renforcement circonférentiels est placée le long de l'armature de carcasse, au moins axialement à l'intérieur, dans la région de bourrelet où le tracé du profil méridien de ladite armature de carcasse change de courbure pour devenir rectiligne ou concave jusqu'au point de tangence T avec la couche d'enrobage quasi circulaire de la première tringle d'ancrage, ladite armature de renforcement ayant son extrémité radialement inférieure radialement au dessous de la droite D', parallèle à l'axe de rotation et passant par le point, de la couche d'enrobage de la première tringle d'ancrage, radialement le plus éloigné de l'axe de rotation, mais au dessus de la droite D, parallèle à l'axe de rotation et passant par le point, de la couche d'enrobage de la première tringle d'ancrage, radialement le plus proche de l'axe de rotation.In order to improve the endurance of the beads of a tire with an H / S shape ratio of less than 0.8, intended to equip a vehicle carrying heavy loads, said tire, according to the invention, comprises at least one frame of radial carcass, formed of at least one ply of inextensible reinforcing elements, anchored in each bead B with at least two rods close to each other, turned around the first and then wrapped around the second to form an inversion, and it is characterized in that, seen in meridian section, an additional reinforcement reinforcement, formed of at least one ply of circumferential reinforcement elements is placed along the carcass reinforcement, at least axially inside, in the bead region where the outline of the meridian profile of said carcass reinforcement changes curvature to become rectilinear or concave up to the point of tangency T with the coating layer almost circular of the first anchor rod, said reinforcing reinforcement having its radially lower end radially below the straight line D ', parallel to the axis of rotation and passing through the point, of the coating layer of the first rod anchor, radially furthest from the axis of rotation, but above the straight line D, parallel to the axis of rotation and passing through the point, of the coating layer of the prem 1st anchor rod, radially closest to the axis of rotation.
L'armature additionnelle de renforcement aura préférentiellement son extrémité radialement supérieure située à une distance radiale de la droite D, comprise entre une quantité égale à la demi-distance radiale entre les droites D et D" augmentée de la demi-distance radiale entre les droites D et D' et une quantité égale à la demi-distance radiale entre les droites D et D" diminuée de la demi-distance radiale entre les droites D et D', la droite D" étant la droite de plus grande largeur axiale.The additional reinforcement preferably has its radially upper end situated at a radial distance from the straight line D, between an amount equal to the radial half-distance between the straight lines D and D "increased by the radial half-distance between the straight lines D and D 'and an amount equal to the radial half-distance between the lines D and D "minus the radial half-distance between the lines D and D', the line D" being the line of greatest axial width.
La droite D" de plus grande largeur axiale est, par définition, la droite parallèle à l'axe de rotation et passant par le point du profil méridien d' armature de carcasse correspondant au point de plus grade largeur axiale lorsque le pneumatique st monté sur sa jante de service et gonflé à la pression recommandée et non chargé.The line D "of greatest axial width is, by definition, the line parallel to the axis of rotation and passing through the point of the meridian profile carcass reinforcement corresponding to the point of highest grade axial width when the tire is mounted on its service rim and inflated to the recommended pressure and not loaded.
Les éléments de l'armature additionnelle de renforcement sont dits circonférentiels si l'angle qu'ils forment avec la direction circonférentielle est compris entre + 5° et - 5°.The elements of the additional reinforcement are said to be circumferential if the angle they form with the circumferential direction is between + 5 ° and - 5 °.
Quel que soit le chemin suivi par l'armature de carcasse pour son ancrage aux deux tringles du bourrelet, par exemple le tracé tel que décrit dans le brevet US 3 301 303 et défini ci-dessus, ou alors un tracé défini par un premier retournement autour de la tringle axialement la plus à l'intérieur en allant de l'intérieur à l'extérieur, puis un passage axialement entre les deux tringles pour se trouver radialement au-dessus de la tringle axialement la plus à l'extérieur, se retourner autour de ladite tringle en allant radialement du haut vers le bas et axialement de l'extérieur vers l'intérieur, et ensuite se retrouver radialement au-dessous de la tringle la plus à l'intérieur, il est avantageux que l'extrémité du retournement soit située radialement sous la tringle axialement la plus à l'intérieur.Whatever the path followed by the carcass reinforcement for its anchoring to the two rods of the bead, for example the path as described in US Patent 3,301,303 and defined above, or else a path defined by a first reversal around the axially innermost rod going from the inside to the outside, then an axially passage between the two rods to be radially above the axially outermost rod, turn around around said rod going radially from top to bottom and axially from outside to inside, and then ending up radially below the innermost rod, it is advantageous for the end of the inversion is located radially under the axially innermost rod.
Une modification avantageuse du bourrelet ainsi obtenu réside dans le fait que la droite joignant les deux centres de gravité des sections transversales de tringles n'est plus parallèle à l'axe de rotation, mais fait avec ce dernier un angle β ouvert axialement et radialement vers l'extérieur compris entre 20° et 60°. Cette structure permet ainsi une reprise partielle des efforts de tension méridiens subis par l'armature de carcasse, et ainsi minimise les déformations possibles de retournement d'armature de carcasse, quelles que soient les conditions de roulage.An advantageous modification of the bead thus obtained lies in the fact that the straight line joining the two centers of gravity of the transverse sections of rods is no longer parallel to the axis of rotation, but makes with the latter an angle β open axially and radially towards outside between 20 ° and 60 °. This structure thus allows a partial recovery of the meridian tension forces undergone by the carcass reinforcement, and thus minimizes the possible deformations of carcass reinforcement overturning, whatever the driving conditions.
La reprise des efforts sera d'autant plus importante que les éléments de renforcement de la nappe additionnelle seront plus nombreux ; ils seront préférentiellement métalliques, en acier et jointifs sur toute la longueur de la nappe de renforcement. Des éléments de renforcement sont dits jointifs, si, dans la direction perpendiculaire auxdits éléments, la distance séparant deux éléments adjacents est réduite au maximum.The resumption of efforts will be all the more important as the reinforcing elements of the additional ply will be more numerous; they will preferably be metallic, steel and joined over the entire length of the reinforcement ply. Reinforcement elements are said to be contiguous if, in the direction perpendicular to said elements, the distance separating two adjacent elements is reduced as much as possible.
La reprise des efforts de tension méridienne d'une armature de carcasse est connue en soi par de nombreux documents. Le brevet FR 750 726 de la demanderesse enseigne le collage des nappes d'armature de carcasse à des armatures auxiliaires, chacune formée de fil enroulé en spirale et présentant en conséquence une flexibilité notable dans le sens transversal. Ledit collage est réalisé de sorte que deux nappes d'armature de carcasse enserrent une armature auxiliaire, ledit enserrement se faisant en l'absence de tringle et de retournement d'armature de carcasse.The resumption of the meridian tension forces of a carcass reinforcement is known in itself from numerous documents. Patent FR 750 726 of the applicant teaches the bonding of carcass reinforcement plies to auxiliary reinforcements, each formed from wire wound in a spiral and consequently having a notable flexibility in the transverse direction. Said bonding is carried out so that two carcass reinforcement plies enclose an auxiliary reinforcement, said clamping being effected in the absence of rod and carcass reinforcement flipping.
Le brevet FR 1 169 474 enseigne aussi de supprimer la tringle usuellement employée par des petites nappes de fils ou câbles métalliques inclinées sur le parallèle d'accrochage, l'angle d'inclinaison pouvant descendre jusqu'à 5°, la (les) nappe(s) d'armature de carcasse étant retournées on non. Le brevet FR 1 234 995 prévoit le remplacement des éléments de renforcement usuellement obliques de la(des) nappe(s) de renforcement de bourrelet destinée(s) à réduire les mouvements de l'accrochage contre le rebord de jante, par des éléments circonférentiels, l'armature de renforcement pouvant être disposée entre la partie principale de l'armature de carcasse et le retournement de ladite armature, ou axialement à l'extérieur dudit retournement d'armature de carcasse.Patent FR 1,169,474 also teaches to remove the rod usually used by small plies of metal wires or cables inclined on the attachment parallel, the angle of inclination being able to descend to 5 °, the ply (s) (s) of carcass reinforcement being returned or not. Patent FR 1 234 995 provides for the replacement of the usually oblique reinforcement elements of the bead reinforcement ply (s) intended to reduce the movements of the attachment against the rim flange, by circumferential elements. , the reinforcing reinforcement being able to be disposed between the main part of the carcass reinforcement and the inversion of said reinforcement, or axially outside said carcass reinforcement inversion.
Nous retrouvons les mêmes armatures de renforcement de bourrelet à éléments circonférentiels dans le brevet FR 1 256 432, lesdits éléments étant destinés à la reprise dans son intégralité des efforts de tension d'armature de carcasse, et dans le cas de pneumatiques pour véhicules de tourisme, en l'absence de tringles d'ancrage ou toute autre nappe de renforcement.We find the same bead reinforcement reinforcements with circumferential elements in patent FR 1 256 432, said elements being intended for the recovery in its entirety of the stresses of carcass reinforcement tension, and in the case of tires for passenger vehicles. , in the absence of anchor rods or any other reinforcement ply.
Le document FR 2 055 988 décrit un certain nombre d'applications possibles d'une armature de renforcement de bourrelet à éléments circonférentiels, en particulier l'utilisation d'une telle armature au lieu et place de l'armature usuelle à éléments obliques disposés axialement à l'extérieur du retournement d'armature de carcasse.Document FR 2 055 988 describes a certain number of possible applications of a bead reinforcement reinforcement with circumferential elements, in particular the use of such a reinforcement instead of the usual reinforcement with oblique elements arranged axially. outside the carcass reinforcement upturn.
Les problèmes d'endurance cités ci-dessus et qui sont influencés par la température de fonctionnement des bourrelets ont été, en très faible partie, résolus par une structure de bourrelet dite amincie, par exemple obtenue par les moyens décrits dans le brevet FR 2 451 016 qui enseigne, dans ce but, de conférer à la paroi extérieure du pneumatique, comprise entre le point où ladite paroi quitte le contact de la jante et le point où ladite paroi atteint sa distance maximale par rapport au plan équatorial, une concavité relativement importante, lorsque le pneumatique est monté sur sa jante de service et gonflé à la pression recommandée.The endurance problems mentioned above and which are influenced by the operating temperature of the beads have been, in very small part, resolved by a bead structure called thinned, for example obtained by the means described in patent FR 2 451 016 which teaches, for this purpose, to impart to the outer wall of the tire, comprised between the point where said wall leaves the contact with the rim and the point where said wall reaches its maximum distance from the equatorial plane, a relatively large concavity, when the tire is mounted on its service rim and inflated to the recommended pressure.
L'armature de carcasse, de manière à réduire le plus possible le volume des bourrelets, est avantageusement formée d'éléments de renforcement en matériau textile, ce qui permet de réaliser aisément les enroulements d'armature autour des tringles. Il est cependant parfois exigé, pour différentes raisons, la présence d'une armature de carcasse métallique en particulier dans les régions du sommet et des flancs du pneumatique. Une solution préférentielle de l'invention consiste alors à doter ledit pneumatique d'une armature de carcasse en trois parties : une première partie d'éléments de renforcement métalliques passant au moins sous l'armature de sommet et dans les flancs, et deux autres parties, formées d'éléments de renforcement textiles, retournées et enroulées autour des deux tringles d'ancrage de chaque bourrelet. Les bords de la partie métallique, partie pouvant être ou non retournée autour des tringles d'ancrage, présentent, avec les bords axialement intérieurs des parties textiles, une longueur commune de chevauchement, au moins située dans la région où se trouve l'armature additionnelle d'éléments de renforcement circonférentiels.The carcass reinforcement, so as to reduce the volume of the beads as much as possible, is advantageously formed of reinforcing elements made of textile material, which makes it possible to easily carry out the armature windings around the rods. However, it is sometimes required, for various reasons, the presence of a metal carcass reinforcement in particular in the regions of the crown and the sidewalls of the tire. A preferred solution of the invention then consists in providing said tire with a carcass reinforcement in three parts: a first part of metallic reinforcing elements passing at least under the crown reinforcement and in the sidewalls, and two other parts , formed of textile reinforcing elements, turned over and wound around the two anchor rods of each bead. The edges of the metal part, part which may or may not be turned around the anchor rods, have, with the axially inner edges of the textile parts, a common length of overlap, at least situated in the region where the additional reinforcement is located. circumferential reinforcing elements.
L'endurance des bourrelets, conformes à l'invention, peut aussi être améliorée par un amincissement desdits bourrelets, en conférant à l'armature de carcasse ancrée à deux tringles dans un bourrelet un profil méridien ne présentant pas de changement de courbure dans la région des bourrelets. Ledit profil méridien est alors caractérisé en ce que, vu en section méridienne, son tracé, compris entre le point A de plus grande largeur axiale et le point de tangence T avec la couche d'enrobage quasi circulaire de la première tringle d'ancrage, est convexe et circulaire sur toute sa longueur, le centre de courbure étant situé sur la droite D" de plus grande largeur axiale, tel que l'épaisseur ε du bourrelet B, mesurée sur une perpendiculaire audit profil méridien en un point C de hauteur hc, comprise entre 30 et 40 mm, mesurée par rapport à la base de bourrelet Y Y', soit comprise entre 2 et 2,5 fois l'épaisseur e du flanc mesurée sur la droite D" de plus grande largeur axiale.The endurance of the beads, in accordance with the invention, can also be improved by a thinning of said beads, by giving the carcass reinforcement anchored to two rods in a bead a meridian profile having no change in curvature in the region. beads. Said meridian profile is then characterized in that, seen in meridian section, its layout, between the point A of greatest axial width and the point of tangency T with the almost circular coating layer of the first anchor rod, is convex and circular over its entire length, the center of curvature being located on the straight line D "of greater axial width, such as the thickness ε of the bead B, measured on a perpendicular to said meridian profile at a point C of height hc, between 30 and 40 mm, measured with respect to the bead base Y Y ', is between 2 and 2.5 times the thickness e of the sidewall measured on the straight line D "of greater axial width.
Non seulement la combinaison de la présence de deux tringles d'ancrage par bourrelet avec la présence d'une armature de renforcement de bourrelet, à éléments circonférentiels, et disposée, conformément à l'invention, à l'intérieur de la partie principale de l'armature de carcasse, permet l'amélioration de l'endurance des bourrelets, mais elle permet en outre, en combinaison avec le profil méridien entièrement convexe de l'armature de carcasse décrit ci-dessus, d'obtenir une très nette diminution du poids du pneumatique tout en n'altérant pas ses propriétés. Ladite diminution de poids peut être avantageusement accentuée par le remplacement des tringles à fils métalliques rectangulaires, généralement utilisées dans le type de pneumatique considéré, par des tringles plus économiques de type "tressé", c'est-à-dire formée d'un tressage hélicoïdal de plusieurs fils métalliques, ou des tringles de type "paquet" à section polygonale, c'est-à-dire des tringles obtenues par l'enroulement sur une forme d'un fil métallique conduisant à plusieurs couches de différentes largeurs. Les types de tringle ci-dessus permettent de plus un moindre encombrement du fait de la forme de leurs sections transversales et de la diminution possible desdites sections, respectivement de l'ordre de 30% et 50% pour chacune , ce qui conduit par rapport à l'application de l'invention au cas de tringles à fils rectangulaires plus encombrantes, à avoir une épaisseur de bourrelet plus amincie.Not only the combination of the presence of two anchor rods per bead with the presence of a bead reinforcement frame, with circumferential elements, and arranged, in accordance with the invention, inside the main part of the carcass reinforcement, improves the endurance of the beads, but it also allows, in combination with the fully convex meridian profile of the carcass reinforcement described above, to obtain a very marked reduction in weight of the tire while not altering its properties. Said reduction in weight can be advantageously accentuated by replacing the rods with rectangular metallic wires, generally used in the type of tire considered, by more economical rods of the "braided" type, that is to say formed from a braiding. helical of several metal wires, or rods of the "package" type with polygonal section, that is to say rods obtained by winding on a form of a metal wire leading to several layers of different widths. The above rod types also allow less size due to the shape of their cross sections and the possible reduction of said sections, respectively of the order of 30% and 50% for each, which leads, in relation to the application of the invention, to rods with more bulky rectangular wires, to have a thinner bead thickness.
L'armature de renforcement de bourrelet ainsi décrite peut être réalisée séparément par enroulement en spirale sur un support horizontal de forme appropriée, et ensuite transférée sur l'ébauche de pneumatique non vulcanisée. La fabrication d'un tel pneumatique sera cependant avantageusement facilitée par l'emploi, à titre d'éléments de renforcement, de tronçons ou d'ensembles ou groupes de tronçons de câbles, de longueur circonférentielle comprise entre 0,2 et 0,4 fois la longueur circonférentielle de la nappe de renforcement, ce qui permet la pose de l'armature de renforcement de bourrelet sur le tambour de confection de l'ébauche crue d'armature de carcasse et la mise sous forme torique de ladite ébauche sans difficultés majeures, et ladite longueur moyenne étant mesurée à la pose sur ledit tambour de confection. Les interstices ou coupures circonférentielles entre éléments coupés sont préférentiellement décalés les uns par rapport aux autres.The bead reinforcement thus described can be produced separately by spiral winding on a horizontal support of suitable shape, and then transferred to the unvulcanized tire blank. The manufacture of such a tire will however advantageously be facilitated by the use, as reinforcing elements, of sections or of sets or groups of sections of cables, of circumferential length between 0.2 and 0.4 times the circumferential length of the reinforcement ply, which allows the fitting of the bead reinforcement reinforcement on the drum for making the raw carcass reinforcement blank and the toroidal shaping of said blank without major difficulties, and said average length being measured when laid on said construction drum. The interstices or circumferential cuts between cut elements are preferably offset with respect to each other.
Les caractéristiques de l'invention seront mieux comprises à l'aide de la description qui suit et qui se réfère au dessin, illustrant à titre non limitatif des exemples d'exécution, et sur lequel :The characteristics of the invention will be better understood with the aid of the description which follows and which refers to the drawing, illustrating non-limiting examples of execution, and in which:
- la figure 1 représente schématiquement une structure de pneumatique, connu par l'état de la technique, - la figure 2 représente schématiquement et en vue agrandie une première variante de bourrelet conforme à l'invention, dans sa version normale,FIG. 1 schematically represents a tire structure, known from the state of the art, FIG. 2 schematically represents and in an enlarged view a first variant of a bead in accordance with the invention, in its normal version,
- la figure 3 représente schématiquement une deuxième variante de bourrelet conforme à l'invention, les tringles étant des tringles tressées et le bourrelet étant aminci,FIG. 3 schematically represents a second variant of bead according to the invention, the rods being braided rods and the bead being thinned,
- la figure 4 représente schématiquement une variante de l'invention avec une armature de carcasse en trois parties.- Figure 4 schematically shows a variant of the invention with a carcass reinforcement in three parts.
Le pneumatique P de l'art antérieur, représenté sur la figure 1 est un pneumatique de dimension 205/75 R 17.5, destiné à être monté sur une jante comportant des sièges de jante J inclinés à 15°. Ledit pneumatique comprend une bande de roulement (4) réunie à deux bourrelets B par l'intermédiaire de deux flancs (5). Chaque bourrelet B est renforcé par une tringle (1) formée par l'enroulement sur une forme appropriée d'un fil à section quadrilatère jusqu'à obtention de plusieurs rangées de fils radialement juxtaposées. Autour de ladite tringle (1) est ancrée une armature de carcasse (2), composée d'une seule nappe de câbles de polyamide aromatique. L'armature de carcasse (2) possède, vue en section méridienne, un profil méridien, entre le point A de plus grande largeur axiale et le point de tangence T dudit profil avec la couche d'enrobage (10) quasi circulaire de la tringle (1) (il est écrit quasi circulaire parce que la couche d'enrobage n'a pratiquement jamais une forme transversale parfaitement circulaire), présentant deux courbures : le profil est convexe du point A au point J d'inflexion situé radialement au-dessus de la tringle, et il est concave dudit point d'inflexion jusqu'au point T de tangence. L'ancrage de l'armature de carcasse (2) se fait par un retournement (20) autour de la couche (10) de mélange caoutchouteux qui recouvre la tringle (1), la distance radiale h, séparant l'extrémité radialement supérieure dudit retournement (20) de la droite YY' (parallèle à l'axe de rotation et définissant le diamètre nominal du bourrelet, qui est aussi, dans le cas présent, celui de la jante) et étant égale, dans l'exemple étudié du pneumatique de dimension 205/75 R 17.5, à 25 mm. Entre l'armature de carcasse (2) et son retournement (20), radialement au dessus de la tringle (1), est disposé un bourrage tringle (71) en mélange caoutchouteux de dureté Shore généralement élevée. Axialement à l'extérieur du retournement (20), se trouve une nappe de renforcement (6) formée de câbles métalliques inextensibles faiblement orientés par rapport à la direction circonférentielle, et dont l'extrémité radialement supérieure est plus éloignée de l'axe de rotation que l'extrémité supérieure du retournement (20) d'armature de carcasse (2). Ladite nappe (6) est d'une part, séparée de l'armature de carcasse (2) et du bourrage tringle (71) par un deuxième bourrage (72) de remplissage, et d'autre part, du mélange caoutchouteux de protection (8) qui entoure le bourrelet, par un troisième bourrage (73).The tire P of the prior art, shown in FIG. 1, is a tire of dimension 205/75 R 17.5, intended to be mounted on a rim comprising rim seats J inclined at 15 °. Said tire comprises a tread (4) joined to two beads B by means of two sidewalls (5). Each bead B is reinforced by a rod (1) formed by winding on a suitable form a wire with a quadrilateral section until several rows of radially juxtaposed wires are obtained. Around said rod (1) is anchored a carcass reinforcement (2), composed of a single ply of aromatic polyamide cables. The carcass reinforcement (2) has, seen in meridian section, a meridian profile, between point A of greater axial width and the point of tangency T of said profile with the almost circular coating layer (10) of the rod (1) (it is written almost circular because the coating layer hardly ever has a perfectly circular transverse shape), presenting two curvatures: the profile is convex of the point A at point J of inflection situated radially above the rod, and it is concave from said point of inflection to point T of tangency. The carcass reinforcement (2) is anchored by an inversion (20) around the layer (10) of rubber mixture which covers the rod (1), the radial distance h, separating the radially upper end of said reversal (20) of the straight line YY '(parallel to the axis of rotation and defining the nominal diameter of the bead, which is also, in this case, that of the rim) and being equal, in the studied example of the tire dimension 205/75 R 17.5, at 25 mm. Between the carcass reinforcement (2) and its upturn (20), radially above the rod (1), is disposed a rod stuffing (71) in a rubber mixture of generally high Shore hardness. Axially outside the turnaround (20), there is a reinforcement ply (6) formed of inextensible metallic cables weakly oriented relative to the circumferential direction, and the radially upper end of which is further from the axis of rotation. that the upper end of the carcass reinforcement upturn (20) (2). Said ply (6) is on the one hand, separated from the carcass reinforcement (2) and the rod stuffing (71) by a second filling stuffing (72), and on the other hand, from the rubbery protective mixture ( 8) which surrounds the bead, by a third stuffing (73).
Le bourrelet B du pneumatique de dimension 205/75 R 17.5, conforme à l'invention et montré sur la figure 2, est renforcé par deux tringles (11) et (12), chacune desdites tringles à fils rectangulaires, c'est-à-dire formée par l'enroulement sur une forme appropriée d'un fil à section rectangulaire jusqu'à obtention de plusieurs rangées de fils radialement juxtaposées, étant enrobée dans un mélange de caoutchouc (110) (120) à haut module d'élongation. La droite joignant les deux centres de gravité des sections transversales de tringles (11) et (12) fait avec l'axe de rotation un angle β, ouvert axialement et radialement vers l'extérieur, égal à 26°. L'armature de carcasse (2) est formée, dans le cas décrit, d'une seule nappe (2) en polyamide aromatique, et son ancrage se fait au moyen des deux tringles (11) et (12) Le profil méridien de ladite armature (2) est, comme défini ci-dessus, tangent en T à la couche d'enrobage quasi circulaire (110) de la première tringle (11), axialement et radialement la plus à l'intérieur, pour s'enrouler ensuite autour de ladite tringle (11) en allant radialement de l'extérieur à l'intérieur et axialement de l'intérieur à l'extérieur, puis se prolonger jusqu'à la deuxième tringle (12), et s'enrouler autour de ladite tringle (12) en allant radialement de l'intérieur vers l'extérieur et axialement de l'extérieur vers l'intérieur et enfin radialement de l'extérieur vers l'intérieur pour aller rejoindre la première tringle (11) axialement à l'extérieur et avoir son extrémité radialement sous ladite première tringle (11). La disposition des bourrages de caoutchouc entre les différents éléments de renforcement est alors modifié comme suit : axialement et radialement à l'extérieur de la tringle axialement intérieure (11) se trouve un premier bourrage (71), axialement et radialement à l'extérieur de la tringle axialement extérieure se trouve un deuxième bourrage (72), alors que, radialement et axialement à l'intérieur de la tringle axialement extérieure (12) se trouve un troisième bourrage (73).The bead B of the tire of size 205/75 R 17.5, in accordance with the invention and shown in FIG. 2, is reinforced by two bead wires (11) and (12), each of said bead wires with rectangular wires, that is to say - said formed by the winding on a suitable form of a wire of rectangular section until several rows of radially juxtaposed wires are obtained, being coated in a rubber mixture (110) (120) with high modulus elongation. The straight line joining the two centers of gravity of the cross sections of rods (11) and (12) makes with the axis of rotation an angle β, open axially and radially outwards, equal to 26 °. The carcass reinforcement (2) is formed, in the case described, of a single ply (2) of aromatic polyamide, and its anchoring is done by means of two rods (11) and (12) The meridian profile of said reinforcement (2) is, as defined above, tangent in T to the quasi-circular coating layer (110) of the first rod (11), axially and radially innermost, to then wind around of said rod (11) going radially from the outside to the inside and axially from the inside to the outside, then extend to the second rod (12), and wrap around said rod ( 12) by going radially from the inside to the outside and axially from the outside to the inside and finally radially from the outside to the inside to join the first rod (11) axially outside and have its end radially under said first rod (11). The arrangement of the rubber jams between the various reinforcing elements is then modified as follows: axially and radially outside the axially inner rod (11) is a first jam (71), axially and radially outside the axially outer rod is a second padding (72), while radially and axially inside the axially outer rod (12) is a third padding (73).
Ladite disposition peut être modifiée en ce sens que le complexe formé par la tringle axialement extérieure (12) entourée de l'enrobage (120) et le bourrage (73) peut être remplacé par un unique bourrage de caoutchouc (73). Il est alors avantageux que le module sécant d'élasticité à la tension dudit bourrage unique soit élevé : mesuré sous 1 % d'allongement relatif, ce module est préférentiellement au moins égal à lO MPa.Said arrangement can be modified in the sense that the complex formed by the axially outer rod (12) surrounded by the coating (120) and the stuffing (73) can be replaced by a single stuffing of rubber (73). It is then advantageous for the secant modulus of elasticity to the tension of said single padding to be high: measured at 1% relative elongation, this modulus is preferably at least equal to lO MPa.
Le profil méridien de l'armature de carcasse (2) est de manière continue convexe entre le point A de plus grande largeur axiale et le point de tangence T à l'enrobage (110) de la tringle (11) axialement la plus à l'intérieur sans présenter de point J d'inflexion. La convexité dudit profil, de rayon unique R, dont le centre de courbure étant situé sur la droite D" de plus grande largeur axiale, est telle que l'épaisseur ε du bourrelet B, mesurée sur une perpendiculaire audit profil méridien en un point C de hauteur hc, égale à 34 mm, mesurée par rapport à la base de bourrelet YY', soit égale à 19 mm, soit 2,5 fois l'épaisseur e du flanc mesurée sur la droite D" de plus grande largeur axiale, alors que l'épaisseur, mesurée dans les mêmes conditions , du bourrelet de la figure 1 est égale à 22 mm.The meridian profile of the carcass reinforcement (2) is continuously convex between the point A of greatest axial width and the point of tangency T to the covering (110) of the rod (11) axially the most interior without showing an inflection point J. The convexity of said profile, of single radius R, the center of curvature of which is situated on the straight line D "of greater axial width, is such that the thickness ε of the bead B, measured on a perpendicular to said meridian profile at a point C of height hc, equal to 34 mm, measured with respect to the bead base YY ', either equal to 19 mm, or 2.5 times the thickness e of the flank measured on the straight line D "of greatest axial width, then that the thickness, measured under the same conditions, of the bead of FIG. 1 is equal to 22 mm.
Le bourrelet est aussi caractérisé par la présence d'une armature de renforcement (6) composée d'une nappe (61) de renforcement de bourrelet, formée d'éléments circonférentiels métalliques en acier qui sont des câbles 19 x 28 métalliques coupés, la longueur desdits éléments ou tronçons de câbles étant égale au quart de la longueur circonférentielle de ladite nappe (61), mesurée à son rayon de pose avant conformation de l'ébauche non vulcanisée d'armature de carcasse, ladite nappe (61) étant placée axialement à l'intérieur de l'armature de carcasse (2) et non axialement à l'extérieur du retournement (20) de l'armature de carcasse (2). Les espaces entre extrémités d'éléments avant conformation de l'ébauche ont de faible amplitude (3 mm) et sont décalés circonférentiellement entre eux.The bead is also characterized by the presence of a reinforcing reinforcement (6) composed of a bead reinforcing ply (61), formed of metallic circumferential elements of steel which are cut metal cables 19 x 28, the length said elements or sections of cables being equal to a quarter of the circumferential length of said ply (61), measured at its laying radius before conformation of the unvulcanized blank of the carcass reinforcement, said ply (61) being placed axially at inside the carcass reinforcement (2) and not axially outside the reversal (20) of the carcass reinforcement (2). The spaces between the ends of elements before shaping the blank have a small amplitude (3 mm) and are offset circumferentially between them.
L'extrémité radialement inférieure de la nappe (61) est distante de l'axe de rotation du pneumatique d'une quantité égale à 227 mm, c'est-à-dire comprise entre la distance de 223 mm séparant de l'axe de rotation la droite D passant par le point, de la couche d'enrobage quasi circulaire (110) de la première tringle d'ancrage (10) le plus proche de l'axe de rotation et la distance de 233 mm séparant de l'axe de rotation la droite D' passant par le point de la couche d'enrobage (110) le plus éloigné dudit axe de rotation.The radially lower end of the ply (61) is distant from the axis of rotation of the tire by an amount equal to 227 mm, that is to say between the distance of 223 mm separating from the axis of rotation the straight line D passing through the point, of the almost circular coating layer (110) of the first anchor rod (10) closest to the axis of rotation and the distance of 233 mm separating from the axis of rotation the straight line D 'passing through the point of the coating layer (110) furthest from said axis of rotation.
Quant à l'extrémité radialement supérieure, elle est située radialement, dans le cas décrit, à une distance re de l'axe de rotation égale à 255 mm, quantité qui est comprise entre une quantité de 265 mm, égale à la demi- somme 260 mm des distances respectives à l'axe de rotation des droites D et D" (297 + 223/2), la droite D" de plus grande largeur axiale passant par le point A étant à 297 mm de l'axe de rotation) augmentée de la demi- distance radiale de 5 mm entre les droites D et D' (233- 223/2), et une quantité de 255 mm, égale à la demi-somme 260 mm des distances respectives à l'axe de rotation des droites D et D" diminuée de la demi- distance radiale de 5 mm entre les droites D et D'.As for the radially upper end, it is located radially, in the case described, at a distance r e from the axis of rotation equal to 255 mm, an amount which is between an amount of 265 mm, equal to half sum 260 mm of the respective distances to the axis of rotation of the straight lines D and D "(297 + 223/2), the straight line D" of greatest axial width passing through the point A being 297 mm from the axis of rotation ) increased by the radial half-distance of 5 mm between the straight lines D and D '(233-223/2), and an amount of 255 mm, equal to the half-sum 260 mm of the respective distances to the axis of rotation lines D and D "minus the radial half-distance of 5 mm between lines D and D '.
Le bourrelet B, montré sur la figure 3, présente, vu en section méridienne, un profil méridien d'armature de carcasse (2) qui, comme dans le cas de la figure 2, entre le point A de plus grande largeur axiale et le point de tangence T dudit profil avec le cercle circonscrit à la couche d'enrobage (110) de la première tringle (11) est de manière continue convexe, sans point d'inflexion J dans la région du bourrelet. Ledit bourrelet de la figure 3 diffère de celui de la figure 2, d'une part par le fait que la première tringle (11) axialement et radialement la plus à l'intérieur est une tringle de type "tressé" qui, à aire de section transversale égale à l'aire de section d'une tringle à fils rectangulaire, permet un encombrement globalement moindre, et d'autre part par le fait que le complexe formé par la tringle axialement extérieure (12) et le profilé de caoutchouc (73) est remplacé par un unique bourrage (73), ce qui accentue l'amincissement du bourrelet et la diminution de poids du pneumatique. La disposition ci-dessus permet d'obtenir une épaisseur de bourrelet ε, mesurée sur une perpendiculaire audit profil méridien en un point C de hauteur hc, égale à 30 mm, mesurée par rapport à la base de bourrelet YY', soit égale à 17 mm, soit 2,2 fois l'épaisseur e du flanc mesurée sur la droite D" de plus grande largeur axiale. La nappe de renforcement de bourrelet (6), composée d'éléments circonférentiels, est, comme dans le cas montré sur la figure 2, placée axialement à l'intérieur de l'armature de carcasse (2) et non axialement à l'extérieur du retournement (20) de l'armature de carcasse (2).Bead B, shown in FIG. 3, has, seen in meridian section, a meridian profile of carcass reinforcement (2) which, as in the case of FIG. 2, between point A of greater axial width and the point of tangency T of said profile with the circle circumscribed to the coating layer (110) of the first rod (11) is continuously convex, without inflection point J in the region of the bead. Said bead in FIG. 3 differs from that in FIG. 2, on the one hand in that the first rod (11) axially and radially innermost is a rod of the "braided" type which, in area of cross section equal to the cross-sectional area of a rectangular wire rod, allows a generally smaller overall size, and secondly by the fact that the complex formed by the axially outer rod (12) and the rubber profile (73 ) is replaced by a single padding (73), which accentuates the thinning of the bead and the reduction in weight of the tire. The above arrangement makes it possible to obtain a bead thickness ε, measured on a perpendicular to said meridian profile at a point C of height h c , equal to 30 mm, measured relative to the bead base YY ', ie equal to 17 mm, or 2.2 times the thickness e of the sidewall measured on the straight line D "of greater axial width. The bead reinforcement ply (6), composed of circumferential elements, is, as in the case shown on Figure 2, placed axially inside the carcass reinforcement (2) and not axially outside the upturn (20) of the carcass reinforcement (2).
Le bourrelet B de la figure 4 diffère de celui de la figure 3 uniquement par le fait que l'armature de carcasse (2) du pneumatique considéré est composée d'une première partie (21) formée de câbles métalliques, et de deux parties (22) formées de câbles textiles. La première partie (21) a, d'une part un tracé de profil méridien passant sous le sommet (non montré) et dans les flancs, et d'autre part deux bords (210) partiellement retournés autour du complexe formé par la tringle d'ancrage (11) et le profilé (73). Chaque deuxième partie a un bord axialement intérieur (220), qui présente avec un bord (210) de la première partie une longueur commune de chevauchement, et telle que l'extrémité radialement supérieure dudit bord soit radialement à l'intérieur de l'extrémité radialement supérieure de la nappe additionnelle de renforcement (61). Ladite deuxième partie est retournée autour de la tringle (11), pour aller ensuite s'enrouler autour de l'unique bourrage (73) et présenter un deuxième bord situé radialement sous la tringle (11).The bead B in FIG. 4 differs from that in FIG. 3 only in that the carcass reinforcement (2) of the tire in question is composed of a first part (21) formed of metallic cables, and of two parts ( 22) formed of textile cables. The first part (21) has, on the one hand a tracing of a meridian profile passing under the summit (not shown) and in the sides, and on the other hand two edges (210) partially turned around the complex formed by the rod d anchor (11) and the profile (73). Each second part has an axially inner edge (220), which has an edge (210) of the first part with a common length of overlap, and such that the radially upper end of said edge is radially inside the end radially upper of the additional reinforcement ply (61). Said second part is turned around the rod (11), to then wrap around the single stuffing (73) and have a second edge located radially under the rod (11).
Les pneumatiques P^B de la dimension décrite et comprenant des bourrelets à deux tringles de type "tressé", un profil d'armature de carcasse aminci et une nappe additionnelle de renforcement de bourrelet à éléments circonférentiels et située axialement à l'intérieur de l'armature de carcasse, ont été comparés :The tires P ^ B of the dimension described and comprising beads with two bead wires of the "braided" type, a thinned carcass reinforcement profile and an additional bead reinforcement ply with circumferential elements and located axially inside the carcass reinforcement, were compared:
- à des pneumatiques P usuels, c'est à dire comprenant des bourrelets d'épaisseur usuelle, ne comportant qu'une seule tringle à fils rectangulaires et où la nappe de renforcement de bourrelet est une nappe de câbles métalliques continus orientés à 22° par rapport à la direction circonférentielle et disposée axialement à l'extérieur du retournement d'armature de carcasse, tel que montré sur la figure 1 du dessin, et- to conventional tires P, that is to say comprising beads of usual thickness, comprising only a single rod with rectangular wires and where the bead reinforcement ply is a ply of continuous metallic cables oriented at 22 ° by relative to the circumferential direction and arranged axially outside the carcass reinforcement upturn, as shown in FIG. 1 of the drawing, and
- à des pneumatiques PA, identiques aux pneumatiques Pχ5 mais avec des bourrelets à deux tringles d'ancrage, et - à des pneumatiques Pβ, identiques aux pneumatiques Py mais des bourrelets amincis, une tringle de type "tressé" et une armature additionnelle de renforcement de bourrelet, à éléments circonférentiels et située axialement à l'intérieur de l'armature de carcasse.- PA tires, identical to Pχ 5 tires but with beads with two anchor rods, and - Pβ tires, identical to Py tires but thinned beads, a bead of the "braided" type and an additional bead reinforcement, with circumferential elements and located axially inside the carcass reinforcement.
La comparaison s'est réalisée sur deux critères de qualité, fondamentaux pour l'endurance des bourrelets de pneumatiques : endurance sous surcharge, et l'endurance sur jante chauffante. Dans les mêmes conditions de roulage pour toutes les enveloppes testées, les pneumatiques Pτ; usuels font en moyenne (2 testés par catégorie) 36 000 km en roulage surchargé et 5 100 km en roulage jante chauffante. Les pneumatiques PA avec des bourrelets à deux tringles font respectivement dans les deux mêmes roulages 27 000 km et 21 000 km, ce qui représente un gain important en endurance sur jante chauffante. Les pneumatiques Pg ont réalisé dans les mêmes conditions de roulage et dans les deux tests 72 000 km et 5 900 km, alors que les pneumatiques PAB ont réalisé 93 000 km et 31 000 km, ce qui représente un progrès considérable. Des pneumatiques Pc comportant des bourrelets à épaisseur normale, deux tringles d'ancrage dans chaque bourrelet et une armature de renforcement additionnelle de bourrelet, à éléments circonférentiels et située axialement à l'intérieur de l'armature de carcasse, ont quant à eux atteint les kilométrages qui suivent : 61 000 km en roulage avec surcharge et 29 000 km en roulage sur jante chauffante.The comparison was made on two quality criteria, fundamental for the endurance of tire beads: endurance under overload, and endurance on a heated rim. Under the same running conditions for all the casings tested, the tires Pτ; usual make an average (2 tested by category) 36,000 km in overloaded driving and 5,100 km in heated rim driving. PA tires with double bead beads make 27,000 km and 21,000 km respectively in the same two runs, which represents a significant gain in endurance on a heated rim. Pg tires have performed under the same driving conditions and in both tests 72 000 km and 5900 km, while the BAP tires have performed 93,000 km and 31,000 km, which represents considerable progress. Pc tires comprising beads of normal thickness, two anchor rods in each bead and an additional bead reinforcement, with circumferential elements and located axially inside the carcass reinforcement, have reached the following mileage: 61,000 km when driving with overload and 29,000 km when driving on a heated rim.
Lesdits résultats montrent de manière très nette l'effet puissant de la présence de deux tringles d'ancrage dans un bourrelet pour la tenue en endurance sur jante chauffante. Par contre, dans un roulage avec surcharge, ladite présence est loin d'être bénéfique, elle est plutôt néfaste dans le cas d'un pneumatique de constitution normale avec des épaisseurs normales et des armatures de renforcement de bourrelet normales. Ladite influence néfaste est, de manière inattendue, annulée dans le cas de pneumatiques où l'on a remplacé l'armature usuelle de renforcement de bourrelet sur le retournement d'armature de carcasse par une armature de renforcement à éléments circonférentiels et située axialement à l'intérieur de l'armature de carcasse, et, de manière encore plus inattendue, transformée en effet bénéfique dans le cas de pneumatiques comportant des bourrelets amincis combinés à la présence de l'armature de renforcement additionnelle à éléments circonférentiels à l'intérieur de l'armature de carcasse, alors que le rendement en roulage sur jante chauffante est encore amélioré, ce qui rend la combinaison P^B particulièrement performante. Said results clearly show the powerful effect of the presence of two anchor rods in a bead for endurance resistance on a heated rim. On the other hand, in a traffic with overload, said presence is far from being beneficial, it is rather harmful in the case of a tire of normal constitution with normal thicknesses and normal bead reinforcement reinforcements. Said harmful influence is, unexpectedly, canceled in the case of tires where the usual reinforcement reinforcement of bead on the reversal of carcass reinforcement has been replaced by a reinforcement with circumferential elements and located axially at the center. inside the carcass reinforcement, and, even more unexpectedly, transformed into a beneficial effect in the case of tires comprising thinned beads combined with the presence of the additional reinforcement reinforcement with circumferential elements inside the carcass reinforcement, while the rolling efficiency on a heated rim is further improved, which makes the combination P ^ B particularly efficient.

Claims

REVENDICATIONS
Pneumatique à rapport de forme H/S inférieur à 0,8, destiné à équiper un véhicule portant de lourdes charges, ledit pneumatique comprenant au moins une armature de carcasse radiale (2), formée d'au moins une nappe (2) d'éléments de renforcement inextensibles, ancrée dans chaque bourrelet B à au moins deux tringles (11, 12) proches l'une de l'autre, retournée autour de la première tringle et ensuite enroulée autour de la deuxième tringle pour former un retournement (20), caractérisé en ce que, vue en section méridienne, une armature additionnelle de renforcement (6), formée d'au moins une nappe (61) d'éléments de renforcement circonférentiels, est placée le long de l'armature de carcasse (2), au moins axialement à l'intérieur, dans la région de bourrelet B où le tracé du profil méridien de ladite armature (2) change de courbure pour devenir rectiligne ou concave jusqu'au point de tangence T avec la couche d'enrobage quasi circulaire de la première tringle d'ancrage (11), ladite armature de renforcement (6) ayant son extrémité radialement inférieure radialement au dessous de la droite D', parallèle à l'axe de rotation et passant par le point, de la couche d'enrobage (110) de la première tringle d'ancrage (11), radialement le plus éloigné de l'axe de rotation, mais au dessus de la droite D, parallèle à l'axe de rotation et passant par le point, de la couche d'enrobage (110) de la première tringle d'ancrage (11), radialement le plus proche de l'axe de rotation. - Pneumatique selon la revendication 1, caractérisé en ce que l'extrémité radialement supérieure de l'armature de renforcement additionnelle (6) est située à une distance radiale de la droite D, comprise entre une quantité égale à la demi-distance radiale entre les droites D et D" augmentée de la demi-distance radiale entre les droites D et D' et une quantité égale à la demi-distance radiale entre les droites D et D" diminuée de la demi-distance radiale entre les droites D et D', la droite D" étant la droite de plus grande largeur axiale.A tire with an H / S shape ratio of less than 0.8, intended to equip a vehicle carrying heavy loads, said tire comprising at least one radial carcass reinforcement (2), formed of at least one ply (2) of inextensible reinforcing elements, anchored in each bead B to at least two rods (11, 12) close to each other, turned around the first rod and then wound around the second rod to form an inversion (20) , characterized in that, seen in meridian section, an additional reinforcement armature (6), formed of at least one ply (61) of circumferential reinforcement elements, is placed along the carcass reinforcement (2) , at least axially inside, in the bead region B where the outline of the meridian profile of said reinforcement (2) changes its curvature to become rectilinear or concave up to the point of tangency T with the almost circular coating layer of the first rod anchor (11), said reinforcing reinforcement (6) having its radially lower end radially below the straight line D ', parallel to the axis of rotation and passing through the point, of the coating layer (110) of the first anchor rod (11), radially furthest from the axis of rotation, but above the straight line D, parallel to the axis of rotation and passing through the point, of the coating layer ( 110) of the first anchor rod (11), radially closest to the axis of rotation. - A tire according to claim 1, characterized in that the radially upper end of the additional reinforcement armature (6) is located at a radial distance from the straight line D, between an amount equal to the radial half-distance between the straight lines D and D "increased by the radial half-distance between the straight lines D and D 'and an amount equal to the radial half-distance between the straight lines D and D" minus the radial half-distance between the straight lines D and D' , the line D "being the line of greatest axial width.
- Pneumatique selon l'une des revendications 1 ou 2, caractérisé en ce que le profil méridien de l'armature de carcasse (2), tangent en T à l'enrobage (110) de la première tringle (11), axialement et radialement la plus à l'intérieur, s'enroule ensuite autour de ladite tringle (11) en allant radialement de l'extérieur à l'intérieur et axialement de l'intérieur à l'extérieur, puis se prolonger axialement vers l'extérieur jusqu'à la deuxième tringle (12), pour s'enrouler autour de ladite tringle (12) en allant radialement de l'intérieur vers l'extérieur et axialement de l'extérieur vers l'intérieur pour former un retournement (20) allant radialement de l'extérieur vers l'intérieur pour aller rejoindre la première tringle (11) axialement à l'intérieur.- Tire according to one of claims 1 or 2, characterized in that the meridian profile of the carcass reinforcement (2), tangent in T to the coating (110) of the first bead wire (11), axially and radially the innermost, then wraps around said rod (11) going radially from the outside to the inside and axially from the inside to the outside, then extending axially outwards until to the second rod (12), to wrap around said rod (12) going radially from the inside to the outside and axially from the outside to the inside to form a reversal (20) going radially from outside towards the inside to join the first rod (11) axially inside.
- Pneumatique selon la revendication 1 , caractérisé en ce que l'extrémité du retournement (20) d'armature de carcasse (2) est situé radialement sous la tringle (11) axialement et radialement la plus à l'intérieur. - Pneumatique selon l'une des revendications 1 à 4, caractérisé en ce que la droite joignant les deux centres de gravité des sections transversales de tringles (11) et (12) fait avec l'axe de rotation un angle β ouvert axialement et radialement vers l'extérieur compris entre 20° et 60°.- A tire according to claim 1, characterized in that the end of the upturn (20) of the carcass reinforcement (2) is located radially under the bead wire (11) axially and radially inward. - A tire according to one of claims 1 to 4, characterized in that the straight line joining the two centers of gravity of the transverse sections of bead wires (11) and (12) forms an angle β open axially and radially with the axis of rotation outwards between 20 ° and 60 °.
- Pneumatique selon l'une des revendications 1 à 5, caractérisé en ce que le complexe formé par la tringle axialement extérieure (12) et le bourrage (73), situé radialement et axialement à l'intérieur de ladite deuxième tringle (12) est remplacé par un unique bourrage de caoutchouc (73), dont le module sécant d'élasticité à la tension est, mesuré sous 1% d'allongement relatif, au moins égal à 10 MPa.- A tire according to one of claims 1 to 5, characterized in that the complex formed by the axially outer bead (12) and the padding (73), located radially and axially inside said second bead (12) is replaced by a single rubber packing (73), the secant modulus of elasticity of the tension of which is measured at 1% relative elongation, at least equal to 10 MPa.
- Pneumatique selon l'une des revendications 1 à 6, caractérisé en ce que le profil méridien de l'armature de carcasse (2) ne présente pas de changement de courbure dans la région des bourrelets B, ledit profil méridien ayant, vu en section méridienne, un tracé, compris entre le point A de plus grande largeur axiale et le point de tangence T avec la couche d'enrobage quasi circulaire (110) de la première tringle d'ancrage (11), est convexe et circulaire sur toute sa longueur, le centre de courbure étant situé sur la droite D" de plus grande largeur axiale, tel que l'épaisseur ε du bourrelet B, mesurée sur une perpendiculaire audit profil méridien en un point C de hauteur hc, comprise entre 30 et 40 mm, mesurée par rapport à la base de bourrelet YY', soit comprise entre 2 et 2,5 fois l'épaisseur e du flanc mesurée sur la droite D" de plus grande largeur axiale. - Pneumatique selon l'une des revendications 1 à 7, caractérisé en ce que les éléments de renforcement circonférentiels de l'armature de renforcement (6) de bourrelet B sont métalliques et en acier.- Tire according to one of claims 1 to 6, characterized in that the meridian profile of the carcass reinforcement (2) does not have any change in curvature in the region of the beads B, said meridian profile having, seen in section meridian, a path, between the point A of greater axial width and the point of tangency T with the almost circular coating layer (110) of the first anchor rod (11), is convex and circular over its whole length, the center of curvature being located on the straight line D "of greatest axial width, such as the thickness ε of the bead B, measured on a perpendicular to said meridian profile at a point C of height hc, between 30 and 40 mm , measured with respect to the bead base YY ', that is to say between 2 and 2.5 times the thickness e of the sidewall measured on the straight line D "of greatest axial width. - A tire according to one of claims 1 to 7, characterized in that the circumferential reinforcing elements of the reinforcing reinforcement (6) of bead B are metallic and made of steel.
- Pneumatique selon l'une des revendications 1 à 8, caractérisé en ce que les tringles d'ancrage (11) et (12) de l'armature de carcasse (2) sont des tringles de type "tressé".- A tire according to one of claims 1 to 8, characterized in that the anchor rods (11) and (12) of the carcass reinforcement (2) are rods of the "braided" type.
- Pneumatique selon l'une des revendications 1 à 9, caractérisé en ce que les éléments de renforcement de l'armature de renforcement (6) de bourrelet B sont des tronçons ou des ensembles de tronçons de câbles métalliques, de longueur circonférentielle comprise entre 0,2 et 0,4 fois la longueur circonférentielle de l'armature de renforcement (6), mesurée à son rayon de pose avant conformation de l'ébauche non vulcanisée d'armature de carcasse.- Tire according to one of claims 1 to 9, characterized in that the reinforcing elements of the reinforcing reinforcement (6) of bead B are sections or sets of sections of metal cables, of circumferential length between 0 , 2 and 0.4 times the circumferential length of the reinforcement reinforcement (6), measured at its laying radius before conformation of the unvulcanized blank of the carcass reinforcement.
- Pneumatique selon l'une des revendications 1 à 10, caractérisé en ce que l'armature de carcasse (2) est formée d'éléments de renforcement en matériau textile.- A tire according to one of claims 1 to 10, characterized in that the carcass reinforcement (2) is formed of reinforcing elements made of textile material.
- Pneumatique selon l'une des revendications 1 à 10, caractérisé en ce que l'armature de carcasse (2) est formée de trois parties : une première partie (21) d'éléments de renforcement métalliques passant au moins sous l'armature de sommet et dans les flancs dudit pneumatique, et deux autres parties (22), formées d'éléments de renforcement textiles, retournées et enroulées autour des deux tringles d'ancrage (11 , 12) de chaque bourrelet B, chaque bord (210) de la partie métallique présentant, avec chaque bord axialement intérieur (220) d'une partie textile, une longueur commune de chevauchement, au moins située dans la région où se trouve l'armature additionnelle (6) d'éléments de renforcement circonférentiels. - Tire according to one of claims 1 to 10, characterized in that the carcass reinforcement (2) is formed of three parts: a first part (21) of metal reinforcing elements passing at least under the reinforcement crown and in the sidewalls of said tire, and two other parts (22), formed of elements of textile reinforcement, turned over and wound around the two anchor rods (11, 12) of each bead B, each edge (210) of the metal part having, with each axially inner edge (220) of a textile part, a length overlapping joint, at least situated in the region where the additional reinforcement (6) of circumferential reinforcing elements is located.
EP98966350A 1998-01-12 1998-12-16 Tyre bead with circumferential reinforcing elements Withdrawn EP1047565A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR9800291 1998-01-12
FR9800291A FR2773518A1 (en) 1998-01-12 1998-01-12 TIRE SADDLE WITH CIRCUMFERENTIAL REINFORCEMENT ELEMENTS
PCT/EP1998/008264 WO1999034989A1 (en) 1998-01-12 1998-12-16 Tyre bead with circumferential reinforcing elements

Publications (1)

Publication Number Publication Date
EP1047565A1 true EP1047565A1 (en) 2000-11-02

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Application Number Title Priority Date Filing Date
EP98966350A Withdrawn EP1047565A1 (en) 1998-01-12 1998-12-16 Tyre bead with circumferential reinforcing elements

Country Status (10)

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US (1) US6463975B1 (en)
EP (1) EP1047565A1 (en)
JP (1) JP4564653B2 (en)
KR (1) KR100697969B1 (en)
CN (1) CN1129532C (en)
BR (1) BR9814586A (en)
CA (1) CA2318333C (en)
FR (1) FR2773518A1 (en)
RU (1) RU2219073C2 (en)
WO (1) WO1999034989A1 (en)

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Also Published As

Publication number Publication date
KR20010034045A (en) 2001-04-25
CN1129532C (en) 2003-12-03
CA2318333C (en) 2004-08-10
RU2219073C2 (en) 2003-12-20
FR2773518A1 (en) 1999-07-16
CN1284030A (en) 2001-02-14
BR9814586A (en) 2000-10-24
JP4564653B2 (en) 2010-10-20
CA2318333A1 (en) 1999-07-15
KR100697969B1 (en) 2007-03-23
US6463975B1 (en) 2002-10-15
JP2002500121A (en) 2002-01-08
WO1999034989A1 (en) 1999-07-15

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