WO2024078955A1 - Optimised architecture of a civil engineering-type tyre - Google Patents

Optimised architecture of a civil engineering-type tyre Download PDF

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Publication number
WO2024078955A1
WO2024078955A1 PCT/EP2023/077541 EP2023077541W WO2024078955A1 WO 2024078955 A1 WO2024078955 A1 WO 2024078955A1 EP 2023077541 W EP2023077541 W EP 2023077541W WO 2024078955 A1 WO2024078955 A1 WO 2024078955A1
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WO
WIPO (PCT)
Prior art keywords
rim
bead
sidewall
tire
hook
Prior art date
Application number
PCT/EP2023/077541
Other languages
French (fr)
Inventor
William License
François BARBARIN
Original Assignee
Compagnie Generale Des Etablissements Michelin
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Filing date
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Application filed by Compagnie Generale Des Etablissements Michelin filed Critical Compagnie Generale Des Etablissements Michelin
Publication of WO2024078955A1 publication Critical patent/WO2024078955A1/en

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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
    • 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
    • B60C15/02—Seating or securing beads on rims
    • B60C15/024—Bead contour, e.g. lips, grooves, or ribs
    • 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
    • B60C2015/0617—Flipper strips, fillers, or chafing strips and reinforcing layers for the construction of the bead comprising a cushion rubber other than the chafer or clinch rubber
    • B60C2015/0621—Flipper strips, fillers, or chafing strips and reinforcing layers for the construction of the bead comprising a cushion rubber other than the chafer or clinch rubber adjacent to the carcass turnup portion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C2200/00—Tyres specially adapted for particular applications
    • B60C2200/06—Tyres specially adapted for particular applications for heavy duty vehicles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C2200/00—Tyres specially adapted for particular applications
    • B60C2200/06—Tyres specially adapted for particular applications for heavy duty vehicles
    • B60C2200/065—Tyres specially adapted for particular applications for heavy duty vehicles for construction vehicles

Definitions

  • the subject of the present invention is a radial tire, intended to equip a heavy vehicle of the civil engineering type and concerns more particularly the bead and the sidewall of such a tire.
  • a radial tire for a heavy civil engineering vehicle within the meaning of the European Tire and Rim Technical Organization or ETRTO standard, is intended to be mounted on a rim whose diameter is at least equal to 25 inches.
  • ETRTO standard European Tire and Rim Technical Organization
  • the invention is described for a large radial tire intended to be mounted on a dumper, in particular vehicles for transporting materials extracted from quarries or surface mines, by intermediate of a rim whose diameter is at least equal to 35 inches and can reach 57 inches, or even 63 inches.
  • the tires are intended to be mounted on rims whose geometric specificities are given in the technical documents of national or international organizations such as European Tire and Rim Technical Organization or ETRTO - European Tire and Rim Technical Organization - or the TRA, Tire and Rim association - Tire and Rim Association, United States association. These documents specify which rim must be used for which tire size, and for objects as technical as civil engineering tires, a single tire size corresponds to a single rim size, up to manufacturing tolerances.
  • a tire and a rim having a geometry of revolution relative to an identical axis of rotation once the tire is mounted on the rim, their geometries are generally described in a meridian plane containing the axis of rotation.
  • the radial, axial and circumferential directions respectively designate the directions perpendicular to the axis of rotation of the tire or the rim, parallel to the axis of rotation and perpendicular to the meridian plane.
  • the circumferential direction is tangent to the circumference of the tire.
  • the expressions “radially interior”, respectively “radially exterior” mean “closer”, respectively “further from the axis of rotation of the tire, respectively from the rim”.
  • axially interior”, respectively “axially exterior”, we mean “closer”, respectively “further from the equatorial plane of the tire, respectively from the rim”.
  • the equatorial plane or median plane of the tire is the plane passing through the middle of the rolling surface and perpendicular to the axis of rotation.
  • the equatorial or median plane of the rim is the plane passing through the middle of the two rim hooks and perpendicular to the axis of rotation.
  • a tire comprises a tread, intended to come into contact with a ground via a rolling surface, the two axial ends of which are connected via two sidewalls with two beads ensuring the mechanical connection between the tire and the rim on which it is intended to be mounted.
  • a radial tire further comprises a reinforcing reinforcement, consisting of a crown reinforcement, radially internal to the tread, and a carcass reinforcement, radially internal to the crown reinforcement.
  • the carcass reinforcement of a radial tire for a heavy vehicle of the civil engineering type usually comprises a carcass layer comprising reinforcements, or reinforcing elements, generally metallic coated with a polymeric material of the elastomer or elastomeric type, obtained by mixing and called coating mixture.
  • a carcass layer comprises a main part, connecting the two beads together and generally winding, in each bead, from the inside to the outside of the tire around a circumferential reinforcing element, most often metallic, called a bead, to form a reversal.
  • the metal reinforcements of a carcass layer are substantially parallel to each other and form, with the circumferential direction, an angle of between 80° and 100°.
  • the diameters of the reinforcing elements of the carcass layers are for civil engineering tires with a diameter at least equal to 1.5 mm.
  • the state-of-the-art carcass reinforcement (see US 5236031) comprises a single layer of carcass without another layer of reinforcing elements.
  • the end of the turnaround is close to the most axially exterior point of the tire, or even radially exterior to it as shown in the cited document. If this end is positioned too close to the bead, there is a risk that under the effect of pressure and heat during intensive use, the reinforcing elements of the carcass layer will pass under the bead causing a loss sudden pressure of the tire.
  • the end of the turnaround is in an intermediate radial position such that its radial distance from the radially innermost point of the tire is less than twice the nominal rim hook height, the end of the turnover is in a zone compression, which increases the risk that the rubber compositions surrounding these ends will crack.
  • Positioning the end of the turnaround near the most axially outer point of the tire prevents the ends of the reinforcing elements from generating the first cracks.
  • the overturning is subjected in the bending zone to traction-compression cycles which can lead to ruptures of the reinforcement elements in fatigue.
  • the inventors set themselves the objective, for a radial tire for a civil engineering type vehicle, of increasing the endurance of the bead.
  • a tire for a civil engineering type vehicle intended to be mounted on a nominal rim, said nominal rim comprising on either side of a median plane perpendicular to the axis of rotation of said rim, a conical rim seat and an edge, of radial height G, formed axially from the inside towards the outside of a first radial part and a hook formed by a first circular part of standardized radius RI and center 01, and a hook end, the tire comprising:
  • a radial carcass reinforcement extending between the two beads and comprising at least one carcass layer comprising metal reinforcements forming an angle, with a circumferential direction, between 80° and 100°, coated with a rubber composition, said carcass layer being anchored in each of the beads by an inversion around a rod, to form a main part extending from one rod to the other, and an inversion, axially external to the main part in each of the beads, and having a free end, • the external surface of the bead being configured in each meridian plane, to be in contact with said nominal rim, the measurement being made on a tire mounted and inflated on said nominal rim at the nominal pressure, on the seat and the edge of the rim to a final point of contact at the circular portion of the nominal rim hook, the last point of contact being the radially outermost point of contact between the nominal rim and the bead, the angle between the radius of the circular portion of the nominal rim passing through said last point of contact and the axial direction being between 80 and 85°
  • the invention consists of a radial civil engineering tire comprising a layer of metal carcass whose bead is configured to have an enlarged contact zone with the rim hook in order to maximize the absorption of the compressive stresses of the rubber compositions to relieve the reinforcing elements of the rollover and the main part of the carcass layer. It is necessary to correctly position the last point of contact between the rim and the bead so that the gain in endurance of the carcass layer is not destroyed by the failure of the rubber compositions of the bead which are in the invention more stressed than in state of the art. This support modifies the deformation in this area of the bead.
  • external surface of the tire we designate the surface which delimits the object.
  • This surface can be radially external, in this case it designates the rolling surface. It can be axially external, in this case it is the surface, of the sides or of the bead, intended to be in contact with the rim. It can be interior and in this case it is intended, once the tire is mounted on its rim, to be in contact with an inflation gas.
  • the current dimensioning of the axially exterior external surface of the beads of civil engineering tires is such that in the mounted inflated position the contact arrives approximately in the middle of the circular part of the rim hook, which is the most effective method. sure to have mechanical continuity between the bead and the sidewall.
  • the upper part of the rim hook then serves to accompany the deformation of the sidewall during the crushing of the tire for the part of the tire located at proximity to the contact area.
  • the rim hook takes up part of the compression force, which leads to a better distribution of the contact forces between the bead and the rim.
  • the angle (Al) between the radius of the circular part of the rim passing through the last point of contact and the axial direction, is determined from the point of intersection of the rim with the axial axis to the last point of contact. contact between the rim hook and the external surface of the bead.
  • the position of the last point of contact with respect to the rim hook can be determined by any relevant measuring means with a feeler for example or by optical or contact profilometry. These measurement methods will also make it possible to determine the values of the other characteristics of the external surface of the tire described in the present invention.
  • a preferred solution is that, the tire being mounted and inflated on the nominal rim, on the axially exterior parts of the bead and the sidewall, the external surface of the bead is connected to the external surface of the sidewall by a most radially interior part of the external surface of the sidewall, said most radially interior part being substantially circular over a portion of a radial height at least equal to 0.2 times RI and at most equal to 0.4 times RI the radius of the rim hook, the center of curvature of said most radially interior part of the external surface of the sidewall being axially interior to said most radially interior part of the external surface of the sidewall.
  • curvature of said most radially interior part of the external surface of the sidewall thus dimensioned and positioned with a center of curvature positioned towards the plane of symmetry of the tire relative to the external surface, makes it possible to avoid having a significant discontinuity at the level of the external surface of the sidewall or having to dimension a sidewall thicker than necessary.
  • substantially circular we mean that in each meridian plane, between the last point of contact and a point on the external surface located radially between 0.2 times and 0.4 times RI, the external surface is located on a curve between two circles of radii varying by 10%.
  • a preferred solution for optimizing the stresses at the junction between the sidewall and the bead is that, the tire being mounted and inflated on the nominal rim, the most radially interior part of the external surface of the sidewall is of the shape substantially circular, following a circle whose center is on the right passing through the center of the circular part of the hook of said rim and the last point of contact, and whose radius R2 is included in 0.25 and 0.4 times the radius RI of the circular part of the hook of said rim.
  • An advantageous solution for ensuring the best continuity of the external surface of the sidewall, particularly between the most radially interior circular part and the part adjacent to it, is that, the tire being mounted and inflated on the nominal rim, the part more radially interior of the external surface of the sidewall is of substantially circular shape over an angular portion between 65° and 75° and measured from the radius formed by the last point of contact and the center of the circle.
  • the outer surface of the sidewall radially outer and adjacent to the most radially inner substantially circular part of the outer surface of the sidewall on a radial height equal to the radial height G of the hook of the nominal rim has a center of curvature axially external to the bead and preferably an average radius of curvature at least equal to 400 mm.
  • the center of curvature of this zone of the sidewall is axially inside the bead in the continuity of the connection between the bead and the sidewall.
  • the invention requires the reconfiguration of the entire zone to ensure correct operation.
  • This reconfiguration of the bead and the adjacent part of the sidewall has the consequence of moving the compression point of the turning of the carcass layer towards a radially outer point compared to the state of the art solution.
  • This point is located in relation to the most axially exterior point of the seat of the rim between 2 and 2.5 times the height (G) of the rim hook.
  • G height
  • a preferred solution is therefore that the tire being mounted inflated on the nominal rim, the distance between the main part of the carcass layer, and its inversion, is minimal at a radial height from the most axially outer point of the seat of the nominal rim , between 2 and 2.5 times the height of the nominal rim hook.
  • the measurement of the distance between the main part of the carcass layer, and its reversal can be done on a meridian section.
  • the distance is measured from the neutral fiber of the carcass layer to the neutral fiber of the turnaround perpendicular to the neutral fiber of the main part of the carcass layer.
  • a bead filler rubber For optimal operation of the bead and the sidewall, it is advantageous for a single rubber composition, called a bead filler rubber, to fill the volume between the main part of the carcass layer, and its reversal, this composition of rubber having a secant extension modulus MA10 at 10% deformation, measured at 23° C according to standard ASTM D 412, at least equal to 5 MPa.
  • a rubber composition adjacent and axially external to the reversal of the carcass layer, at least radially external to said last point of contact of the external surface of the bead has a secant extension modulus MA10 at 10% deformation, measured at 23° C according to standard ASTM D 412, at least equal to 90% and preferably at most equal to 110% of the modulus d MA10 rod filler extension.
  • FIG. 1 the outline of a conical seat rim (1) is shown for tires of dimensions 25, 29, 33, 35, 49, 51, 57 and 63 inches as presented in the documentation of the “tyre and Rim association” (association of tires and wheels).
  • This contour represents the section of a rim comprising on either side of a median plane perpendicular to the axis of rotation (O Y) of said rim, a conical rim seat (11) and an edge (12), of a radial height G, formed axially from the inside towards the outside of a first radial part (121) and a hook (122) formed by a first circular part of standardized radius RI and center 01 (see . figure 2 and 3), and a hook end.
  • the figure also shows the most axially outer point (111) of the seat (11) of the rim on the contact surface with the tire.
  • the seat (11) of the nominal rim is linked to the edge (12) by a fillet, the fillet would be considered as the start of the edge (12).
  • Figure 2 shows the detail of a meridian section of a tire for a heavy vehicle of the civil engineering type mounted, inflated on its rim (1), and in particular the sidewall (2), and the bead (3).
  • the bead (3) has an external surface (31) extending by an external surface of the sidewall (21).
  • the radial carcass reinforcement comprises a carcass layer (4) anchored in the bead by an inversion around a rod (5), to form a main part (41) extending from one rod to the other, and a turnaround (42), axially exterior to the main part (41) in each of the beads (3), and having a free end (421).
  • the outer surface (31) of the bead is configured to be in contact with the nominal rim (1), up to the radially outermost contact point (311) on the central circular portion (01) of the rim hook, l 'corner (Al) between the radius of the circular part of the rim passing through said last (311) point of contact and the axial direction being between 80 and 85°.
  • the angle (Al) between the radius of the circular part of the rim passing through the last point of contact and the axial direction is determined from a point of intersection of the rim with the axis axial to the last point of contact between the rim hook and the external surface of the bead.
  • Figure 2 also shows the distance (d) between the main part (41) of the carcass layer (4), and its reversal (42) which is continuously decreasing until its minimum (dm) located at a radial height ( hm) from the most axially outer point of the seat (111) of the rim, between 2 and 2.5 times the height (G) of the rim hook.
  • a single rubber composition called a bead filler rubber (32), fills the volume between the main part (41) of the carcass layer (4), and its reversal (42), adjacent and axially interior to a composition (22). ) of rubber.
  • Figure 2 also shows the profile (21') of a tire according to the state of the art.
  • Figure 3 is a zoom on the bead to show the transition between the bead and the sidewall around the last point of contact (311) between the external surface (31) of the bead (3) and the nominal rim (1 ).
  • the external surface (21) of the sidewall (2) is in its most radially interior part (211) of substantially circular shape, following a circle whose center (02) is on the straight line passing through the center (01) of the circular part of the hook (122) and the last point of contact (311), and whose radius R2 is included in 0.25 and 0.4 times the radius RI of the circular part of the hook (122) of said rim (1), on a angular portion (A2) between 65 and 75° and measured from the radius formed by the last point of contact (311) and the center (02) of the circle.
  • the invention was tested on tires of size 24.00R35.
  • the tires according to the invention are compared to reference tires of the same size.
  • the reference tires and the tires according to the invention comprise a single layer of carcass whose metal reinforcements are cables of 7 strands comprising 7 steel wires of 23 hundredths of 2.24 mm in diameter arranged in a pitch of 2.6 mm under the rod.
  • the turnarounds for both tires have their free ends (421) near the most axially outer point of the tire.
  • the rubber compositions used are equivalent for both solutions.
  • the geometry of the external surface of the bead has been modified such that the last point of contact (311) has an angle Al close to 60° for the control tire and, for the tire according to the invention, an angle equal to 81.3°.
  • connection to the point of contact is made by a substantially circular curve over the entire part of the sidewall between the last point of contact (311) and the most axially external point of the tire, curve whose center of curvature is axially interior to the bead.
  • connection between the bead and the sidewall is made by a circular portion over an angular portion of 69°, the center of this angular portion being on the right extending the radius of the circular part of the hook of rim passing through the last point of contact (311) between the external surface (31) of the bead (3) and the rim (1).
  • the radius of this circular part is equal to 0.3 times the radius RI of the circular part of the rim (1).
  • the distance (d) between the main part (41) of the carcass layer (4), and its turn (42) is minimum at a radial height (hm) of the most axially outer point of the seat (111) of the rim , equal to 2.1 times the height (G) of the rim hook for the invention against 1.0 times the height (G) for the reference tire.
  • the tires are tested on a machine. They are previously planed to the bottom of the sculpture in order to concentrate the stresses on the sides and the beads. The profile of the tread of the planed tire corresponding to the profile of the new tread. Two tires are crushed on top of each other with a force of 25,000 daN corresponding to the nominal load plus 25% overload at 6.2 bar pressure, i.e. a pressure 1.05 bar lower than the nominal pressure. The tires roll on top of each other at a speed of 15 km/h.
  • the tire according to the invention performed more than 1000 hours of driving without damage when the tire according to the state of the art was stopped on a break in the rubber mixtures in the sidewall, in the part adjacent to the rim hook, after 600 hours.
  • the invention provides an improvement of at least 66% in the endurance performance of the sidewall and the bead for overloaded and underinflated use.

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

Abstract

Radial tyre for a civil engineering vehicle, intended to be mounted on a nominal rim (1) comprising a hook (122) having a circular part. The portion of the outer surface (31) of the bead is configured to be in contact with the nominal rim (1) up to a point (311) of contact with the circular portion of the rim hook, the angle (A1) between the radius of the circular portion of the rim, passing through said contact point (311), and the axial direction being between 80 and 85°.

Description

Description Description
Titre • Architecture optimisée d’un pneumatique de type Génie Civil Title • Optimized architecture of a Civil Engineering type tire
[0001] La présente invention a pour objet un pneumatique radial, destiné à équiper un véhicule lourd de type génie civil et concerne plus particulièrement le bourrelet et le flanc d’un tel pneumatique. [0001] The subject of the present invention is a radial tire, intended to equip a heavy vehicle of the civil engineering type and concerns more particularly the bead and the sidewall of such a tire.
[0002] Les pneumatiques radiaux destinés à équiper un véhicule lourd de type génie civil, sont désignés au sens de la norme de la European Tyre and Rim Technical Organisation ou ETRTO - Organisation technique européenne du pneu et de la jante. [0002] Radial tires intended to equip a heavy civil engineering type vehicle are designated within the meaning of the standard of the European Tire and Rim Technical Organization or ETRTO - European Tire and Rim Technical Organization.
[0003] Par exemple un pneumatique radial pour véhicule lourd de type génie civil, au sens de la norme de la European Tyre and Rim Technical Organisation ou ETRTO, est destiné à être monté sur une jante dont le diamètre est au moins égal à 25 pouces. Bien que non limitée à ce type d’application, l’invention est décrite pour un pneumatique radial de grande dimension destiné à être monté sur un dumper, notamment des véhicules de transport de matériaux extraits de carrières ou de mines de surface, par l’intermédiaire d’une jante dont le diamètre est au moins égal à 35 pouces et peut atteindre 57 pouces, voire 63 pouces. [0003] For example, a radial tire for a heavy civil engineering vehicle, within the meaning of the European Tire and Rim Technical Organization or ETRTO standard, is intended to be mounted on a rim whose diameter is at least equal to 25 inches. . Although not limited to this type of application, the invention is described for a large radial tire intended to be mounted on a dumper, in particular vehicles for transporting materials extracted from quarries or surface mines, by intermediate of a rim whose diameter is at least equal to 35 inches and can reach 57 inches, or even 63 inches.
[0004] Les pneumatiques sont destinés à être montés sur des jantes dont les spécificités géométriques sont données dans les documents techniques des organisations nationales ou internationales comme European Tyre and Rim Technical Organisation ou ETRTO - Organisation technique européenne du pneu et de la jante - ou la TRA, Tire and Rim association - Association du pneumatique et de la jante, association des états unis. Ces documents précisent quelle jante doit être utilisée pour quelle dimension de pneumatique, et pour des objets aussi techniques que des pneumatiques de génie civil, à une dimension de pneumatique correspond une unique dimension de jante, aux tolérances de fabrication près. [0004] The tires are intended to be mounted on rims whose geometric specificities are given in the technical documents of national or international organizations such as European Tire and Rim Technical Organization or ETRTO - European Tire and Rim Technical Organization - or the TRA, Tire and Rim association - Tire and Rim Association, United States association. These documents specify which rim must be used for which tire size, and for objects as technical as civil engineering tires, a single tire size corresponds to a single rim size, up to manufacturing tolerances.
[0005] Un pneumatique et une jante ayant une géométrie de révolution par rapport à un axe de rotation identique une fois le pneumatique monté sur la jante, leurs géométries sont généralement décrites dans un plan méridien contenant l’axe de rotation. Pour un plan méridien donné, les directions radiale, axiale et circonférentielle désignent respectivement les directions perpendiculaire à l’axe de rotation du pneumatique ou de la jante, parallèle à l’axe de rotation et perpendiculaire au plan méridien. La direction circonférentielle est tangente à la circonférence du pneumatique. [0005] A tire and a rim having a geometry of revolution relative to an identical axis of rotation once the tire is mounted on the rim, their geometries are generally described in a meridian plane containing the axis of rotation. For a given meridian plane, the radial, axial and circumferential directions respectively designate the directions perpendicular to the axis of rotation of the tire or the rim, parallel to the axis of rotation and perpendicular to the meridian plane. The circumferential direction is tangent to the circumference of the tire.
[0006] Dans ce qui suit, les expressions «radialement intérieur», respectivement «radialement extérieur» signifient «plus proche », respectivement «plus éloigné de l’axe de rotation du pneumatique, respectivement de la jante ». Par «axialement intérieur», respectivement «axialement extérieur», on entend «plus proche», respectivement «plus éloigné du plan équatorial du pneumatique, respectivement de la jante». Le plan équatorial ou plan médian du pneumatique est le plan passant par le milieu de la surface de roulement et perpendiculaire à l’axe de rotation. De même, le plan équatorial ou médian de la jante est le plan passant par le milieu des deux crochets de jante et perpendiculaire à l’axe de rotation. [0006] In what follows, the expressions “radially interior”, respectively “radially exterior” mean “closer”, respectively “further from the axis of rotation of the tire, respectively from the rim”. By “axially interior”, respectively “axially exterior”, we mean “closer”, respectively “further from the equatorial plane of the tire, respectively from the rim”. The equatorial plane or median plane of the tire is the plane passing through the middle of the rolling surface and perpendicular to the axis of rotation. Likewise, the equatorial or median plane of the rim is the plane passing through the middle of the two rim hooks and perpendicular to the axis of rotation.
[0007] De façon générale, un pneumatique comprend une bande de roulement, destinée à venir en contact avec un sol par l’intermédiaire d’une surface de roulement, dont les deux extrémités axiales sont reliées par l’intermédiaire de deux flancs à deux bourrelets assurant la liaison mécanique entre le pneumatique et la jante sur laquelle il est destiné à être monté. [0007] Generally, a tire comprises a tread, intended to come into contact with a ground via a rolling surface, the two axial ends of which are connected via two sidewalls with two beads ensuring the mechanical connection between the tire and the rim on which it is intended to be mounted.
[0008] Un pneumatique radial comprend en outre une armature de renforcement, constituée d’une armature de sommet, radialement intérieure à la bande de roulement, et d’une armature de carcasse, radialement intérieure à l’armature de sommet. [0008] A radial tire further comprises a reinforcing reinforcement, consisting of a crown reinforcement, radially internal to the tread, and a carcass reinforcement, radially internal to the crown reinforcement.
[0009] L’armature de carcasse d’un pneumatique radial pour véhicule lourd de type génie civil, comprend habituellement une couche de carcasse comprenant des renforts, ou éléments de renforcement, généralement métalliques enrobés par un matériau polymérique de type élastomère ou élastomérique, obtenu par mélangeage et appelé mélange d’enrobage. Une couche de carcasse comprend une partie principale, reliant les deux bourrelets entre eux et s’enroulant généralement, dans chaque bourrelet, de l’intérieur vers l’extérieur du pneumatique autour d’un élément de renforcement circonférentiel le plus souvent métallique appelé tringle, pour former un retournement. Les renforts métalliques d’une couche de carcasse sont sensiblement parallèles entre eux et forment, avec la direction circonférentielle, un angle compris entre 80° et 100°. Les diamètres des éléments de renforcement des couches de carcasse sont pour les pneumatiques de génie civil d’un diamètre au moins égal à 1.5 mm. [0009] The carcass reinforcement of a radial tire for a heavy vehicle of the civil engineering type usually comprises a carcass layer comprising reinforcements, or reinforcing elements, generally metallic coated with a polymeric material of the elastomer or elastomeric type, obtained by mixing and called coating mixture. A carcass layer comprises a main part, connecting the two beads together and generally winding, in each bead, from the inside to the outside of the tire around a circumferential reinforcing element, most often metallic, called a bead, to form a reversal. The metal reinforcements of a carcass layer are substantially parallel to each other and form, with the circumferential direction, an angle of between 80° and 100°. The diameters of the reinforcing elements of the carcass layers are for civil engineering tires with a diameter at least equal to 1.5 mm.
[0010] En génie civil, l’armature de carcasse de l’état de l’art (cf. US 5236031) comprend une unique couche de carcasse sans autre couche d’éléments de renforcement. L’extrémité du retournement est proche du point le plus axialement extérieur du pneumatique, voire radialement extérieure à celui-ci comme le montre le document cité. Si cette extrémité est positionnée trop proche de la tringle, il y a un risque que sous l’effet de la pression et de la chaleur lors d’usages intensifs, les éléments de renforcement de la couche de carcasse passent sous la tringle provoquant une perte de pression brutale du pneumatique. Si l’extrémité du retournement se trouve dans une position radiale intermédiaire telle que sa distance radiale au point le plus radialement intérieur du pneumatique soit inférieure à deux fois la hauteur du crochet de la jante nominale, l’extrémité du retournement se trouve dans une zone de compression, ce qui augmente le risque que les compositions de caoutchouc entourant ces extrémités se fissurent. Positionner l’extrémité du retournement à proximité du point le plus axialement extérieur du pneumatique, permet d’éviter que les extrémités des éléments de renforcement soient les génératrices des premières fissures. Cependant le retournement est soumis dans la zone de flexion à des cycles de traction compression pouvant conduire à des ruptures des éléments de renforcement en fatigue. L’état de l’art (cf. US 5236031) propose de rapprocher le retournement de la partie principale de la couche de carcasse afin de diminuer les contraintes de flexion, le bourrelet ayant le comportement d’une poutre. Cependant cette solution est compliquée par le diamètre des éléments de renforcement des couches de carcasse des pneumatiques de génie civil. Compte tenu de leur rigidité de flexion, il est difficile de les maintenir pendant tout le procédé de fabrication dans la position idéale pour l’endurance du pneumatique. [0010] In civil engineering, the state-of-the-art carcass reinforcement (see US 5236031) comprises a single layer of carcass without another layer of reinforcing elements. The end of the turnaround is close to the most axially exterior point of the tire, or even radially exterior to it as shown in the cited document. If this end is positioned too close to the bead, there is a risk that under the effect of pressure and heat during intensive use, the reinforcing elements of the carcass layer will pass under the bead causing a loss sudden pressure of the tire. If the end of the turnaround is in an intermediate radial position such that its radial distance from the radially innermost point of the tire is less than twice the nominal rim hook height, the end of the turnover is in a zone compression, which increases the risk that the rubber compositions surrounding these ends will crack. Positioning the end of the turnaround near the most axially outer point of the tire prevents the ends of the reinforcing elements from generating the first cracks. However, the overturning is subjected in the bending zone to traction-compression cycles which can lead to ruptures of the reinforcement elements in fatigue. The state of the art (see US 5236031) proposes to bring the reversal closer to the main part of the carcass layer in order to reduce the bending stresses, the bead having the behavior of a beam. However, this solution is complicated by the diameter of the reinforcing elements of the carcass layers of civil engineering tires. Given their bending rigidity, it is difficult to maintain them throughout the manufacturing process in the ideal position for the endurance of the tire.
[0011] Cette solution ne permet néanmoins pas de résoudre l’ensemble des problèmes d’endurance du bourrelet et de la couche de carcasse à sa périphérie. En effet, sur les sols irréguliers où sont utilisés les pneumatiques de génie civil, la vitesse toujours plus élevée des engins, pour améliorer leur productivité, crée des phénomènes de résonance lors de décollements du pneumatique du sol suivis de rebonds qui impliquent des surcharges dynamiques très importantes pouvant aller jusqu’à 2 fois la charge nominale. A ce phénomène s’ajoute des pratiques néfastes pour l’endurance du bourrelet comme des usages avec des pressions plus basses que celles préconisées ou l’augmentation de la charge au-delà de la charge nominale. La baisse de pression est utilisée pour améliorer l’endurance du sommet aux chocs mais elle implique une augmentation des déformations de la couche de carcasse au-dessus du bourrelet. Par ailleurs l’électrification des moteurs en raison du poids des batteries conduira également à devoir améliorer l’endurance des bourrelets en surcharge. [0011] This solution does not, however, make it possible to resolve all of the endurance problems of the bead and of the carcass layer at its periphery. Indeed, on uneven ground where civil engineering tires are used, the ever-increasing speed of the machines, to improve their productivity, creates resonance phenomena when the tire separates from the ground followed by rebounds which imply overloads. very significant dynamics which can go up to 2 times the nominal load. Added to this phenomenon are practices that are harmful to the endurance of the bead, such as using pressures lower than those recommended or increasing the load beyond the nominal load. The pressure drop is used to improve the endurance of the crown to shocks but it implies an increase in the deformation of the carcass layer above the bead. Furthermore, the electrification of motors due to the weight of the batteries will also lead to the need to improve the endurance of the overload beads.
[0012] Les inventeurs se sont donnés pour objectif, pour un pneumatique radial pour véhicule de type génie civil, d’augmenter l’endurance du bourrelet. [0012] The inventors set themselves the objective, for a radial tire for a civil engineering type vehicle, of increasing the endurance of the bead.
[0013] Cet objectif a été atteint, selon l’invention, par un pneumatique pour véhicule de type génie civil destiné à être monté sur une jante nominale, ladite jante nominale comprenant de part et d’autre d’un plan médian perpendiculaire à l’axe de rotation de ladite jante, un siège de jante conique et un bord, d’hauteur radiale G, formé axialement de l’intérieur vers l’extérieur d’une première partie radiale et d’un crochet formé par une première partie circulaire de rayon normé RI et de centre 01, et d’une fin de crochet, le pneumatique comprenant : [0013] This objective was achieved, according to the invention, by a tire for a civil engineering type vehicle intended to be mounted on a nominal rim, said nominal rim comprising on either side of a median plane perpendicular to the axis of rotation of said rim, a conical rim seat and an edge, of radial height G, formed axially from the inside towards the outside of a first radial part and a hook formed by a first circular part of standardized radius RI and center 01, and a hook end, the tire comprising:
• une armature de sommet, radialement intérieure à une bande de roulement, ladite bande de roulement étant réunie par l’intermédiaire de deux flancs, à deux bourrelets, • a crown reinforcement, radially internal to a tread, said tread being joined via two sidewalls, with two beads,
• chaque bourrelet ayant une surface externe se prolongeant par une surface externe du flanc, • each bead having an external surface extending through an external surface of the sidewall,
• une armature de carcasse radiale s’étendant entre les deux bourrelets et comprenant au moins une couche de carcasse comportant des renforts métalliques formant un angle, avec une direction circonférentielle, compris entre 80° et 100°, enrobés par une composition de caoutchouc, ladite couche de carcasse étant ancrée dans chacun des bourrelets par un retournement autour d’une tringle, pour former une partie principale s’étendant d’une tringle à l’autre, et un retournement, axialement extérieur à la partie principale dans chacun des bourrelets, et ayant une extrémité libre, • la surface externe du bourrelet étant configurée dans chaque plan méridien, pour être en contact avec ladite jante nominale, la mesure étant faite sur un pneumatique monté et gonflé sur ladite jante nominale à la pression nominale, sur le siège et le bord de la jante jusqu’à un dernier point de contact à la partie circulaire du crochet de jante nominale, le dernier point de contact étant le point de contact le plus radialement extérieur entre la jante nominale et le bourrelet, l’angle entre le rayon de la partie circulaire de la jante nominale passant par ledit dernier point de contact et la direction axiale étant compris entre 80 et 85°. • a radial carcass reinforcement extending between the two beads and comprising at least one carcass layer comprising metal reinforcements forming an angle, with a circumferential direction, between 80° and 100°, coated with a rubber composition, said carcass layer being anchored in each of the beads by an inversion around a rod, to form a main part extending from one rod to the other, and an inversion, axially external to the main part in each of the beads, and having a free end, • the external surface of the bead being configured in each meridian plane, to be in contact with said nominal rim, the measurement being made on a tire mounted and inflated on said nominal rim at the nominal pressure, on the seat and the edge of the rim to a final point of contact at the circular portion of the nominal rim hook, the last point of contact being the radially outermost point of contact between the nominal rim and the bead, the angle between the radius of the circular portion of the nominal rim passing through said last point of contact and the axial direction being between 80 and 85°.
[0014] L’invention consiste en un pneumatique radial de Génie civil comprenant une couche de carcasse métallique dont le bourrelet est configuré pour avoir une zone de contact élargi avec le crochet de jante afin de maximiser la reprise des contraintes de compression des compositions de caoutchouc pour soulager les éléments de renforcement du retournement et de la partie principale de la couche de carcasse. Il convient de positionner correctement le dernier point de contact entre la jante et le bourrelet afin que le gain en endurance de la couche de carcasse ne soit pas détruit par la défaillance des compositions de caoutchouc du bourrelet qui sont dans l’invention plus sollicitées que dans l’état de l’art. Cet appui modifie la déformation dans cette zone du bourrelet. [0014] The invention consists of a radial civil engineering tire comprising a layer of metal carcass whose bead is configured to have an enlarged contact zone with the rim hook in order to maximize the absorption of the compressive stresses of the rubber compositions to relieve the reinforcing elements of the rollover and the main part of the carcass layer. It is necessary to correctly position the last point of contact between the rim and the bead so that the gain in endurance of the carcass layer is not destroyed by the failure of the rubber compositions of the bead which are in the invention more stressed than in state of the art. This support modifies the deformation in this area of the bead.
[0015] Par surface externe du pneumatique, on désigne la surface qui délimite l’objet. Cette surface peut-être radialement extérieure, elle désigne dans ce cas la surface de roulement. Elle peut être axialement extérieure, elle est dans ce cas la surface, des flancs ou du bourrelet, destinée à être en contact avec la jante. Elle peut être intérieure et dans ce cas elle est destinée une fois le pneumatique monté sur sa jante à être en contact avec un gaz de gonflage. [0015] By external surface of the tire, we designate the surface which delimits the object. This surface can be radially external, in this case it designates the rolling surface. It can be axially external, in this case it is the surface, of the sides or of the bead, intended to be in contact with the rim. It can be interior and in this case it is intended, once the tire is mounted on its rim, to be in contact with an inflation gas.
[0016] Ainsi le dimensionnement actuel de la surface externe axialement extérieure des bourrelets des pneumatiques de génie civil est tel qu’en position monté gonflé le contact arrive approximativement au milieu de la partie circulaire du crochet de jante, ce qui est la méthode la plus sure d’avoir une continuité mécanique entre le bourrelet et le flanc. La partie supérieure du crochet de jante sert alors à accompagner la déformation du flanc lors de l’écrasement du pneumatique pour la partie du pneumatique située à proximité de l’aire de contact. Cette solution est d’autant plus intéressante que l’armature de carcasse comprend une unique couche de carcasse. [0016] Thus the current dimensioning of the axially exterior external surface of the beads of civil engineering tires is such that in the mounted inflated position the contact arrives approximately in the middle of the circular part of the rim hook, which is the most effective method. sure to have mechanical continuity between the bead and the sidewall. The upper part of the rim hook then serves to accompany the deformation of the sidewall during the crushing of the tire for the part of the tire located at proximity to the contact area. This solution is all the more interesting as the carcass reinforcement comprises a single layer of carcass.
[0017] Dans l’invention le crochet de jante reprend une partie de l’effort de compression ce qui amène une meilleure répartition des efforts de contact entre le bourrelet et la jante. Pour cela, il est important que le dernier point de contact entre le crochet de jante et la surface externe du bourrelet soit dans une position particulière par rapport au crochet de jante à savoir que l’angle (Al) entre le rayon de la partie circulaire de la jante passant par le dernier point de contact et la direction axiale doit être compris entre 80 et 85°. En deçà de cet angle, le fonctionnement du bourrelet reste le même, au- delà de cet angle, la continuité de raccordement du bourrelet au flanc implique une géométrie non optimale du pneumatique. L’angle (Al) entre le rayon de la partie circulaire de la jante passant par le dernier point de contact et la direction axiale, est déterminé depuis le point d’intersection de la jante avec l’axe axial jusqu’au dernier point de contact entre le crochet de jante et la surface externe du bourrelet. [0017] In the invention, the rim hook takes up part of the compression force, which leads to a better distribution of the contact forces between the bead and the rim. For this, it is important that the last point of contact between the rim hook and the external surface of the bead is in a particular position relative to the rim hook, namely that the angle (Al) between the radius of the circular part of the rim passing through the last point of contact and the axial direction must be between 80 and 85°. Below this angle, the operation of the bead remains the same, beyond this angle, the continuity of connection of the bead to the sidewall implies a non-optimal geometry of the tire. The angle (Al) between the radius of the circular part of the rim passing through the last point of contact and the axial direction, is determined from the point of intersection of the rim with the axial axis to the last point of contact. contact between the rim hook and the external surface of the bead.
[0018] La position du dernier point de contact vis-à-vis du crochet de jante peut être déterminée par tout moyen de mesure pertinent avec un palpeur par exemple ou par profilométrie optique ou de contact. Ces méthodes de mesure permettront également de déterminer les valeurs des autres caractéristiques de la surface externe du pneumatique décrite dans la présente invention. [0018] The position of the last point of contact with respect to the rim hook can be determined by any relevant measuring means with a feeler for example or by optical or contact profilometry. These measurement methods will also make it possible to determine the values of the other characteristics of the external surface of the tire described in the present invention.
[0019] Pour éviter une concentration de contrainte à la zone de jonction entre le flanc et le bourrelet, une solution préférée est que, le pneumatique étant monté et gonflé sur la jante nominale, sur les parties axial ement extérieures du bourrelet et du flanc, la surface externe du bourrelet soit reliée à la surface externe du flanc par une partie la plus radialement intérieure de la surface externe du flanc, ladite partie la plus radialement intérieure étant sensiblement circulaire sur une portion d’une hauteur radiale au moins égale à 0.2 fois RI et au plus égale à 0.4 fois RI le rayon du crochet de jante, le centre de courbure de ladite partie la plus radialement intérieure de la surface externe du flanc étant axialement intérieur à ladite partie la plus radialement intérieure de la surface externe du flanc. La courbure de ladite partie la plus radialement intérieure de la surface externe du flanc ainsi dimensionnée et positionnée avec un centre de courbure positionné vers le plan de symétrie du pneumatique par rapport à la surface externe, permet d’éviter d’avoir une discontinuité importante au niveau de la surface externe du flanc ou de devoir dimensionner un flanc plus épais que nécessaire. Par sensiblement circulaire, on entend que dans un chaque plan méridien, entre le dernier point de contact et un point de la surface externe situé radial ement entre 0.2 fois et 0.4 fois RI, la surface externe est située sur une courbe comprise entre deux cercles de rayons variants de 10%. [0019] To avoid a concentration of stress at the junction zone between the sidewall and the bead, a preferred solution is that, the tire being mounted and inflated on the nominal rim, on the axially exterior parts of the bead and the sidewall, the external surface of the bead is connected to the external surface of the sidewall by a most radially interior part of the external surface of the sidewall, said most radially interior part being substantially circular over a portion of a radial height at least equal to 0.2 times RI and at most equal to 0.4 times RI the radius of the rim hook, the center of curvature of said most radially interior part of the external surface of the sidewall being axially interior to said most radially interior part of the external surface of the sidewall. The curvature of said most radially interior part of the external surface of the sidewall thus dimensioned and positioned with a center of curvature positioned towards the plane of symmetry of the tire relative to the external surface, makes it possible to avoid having a significant discontinuity at the level of the external surface of the sidewall or having to dimension a sidewall thicker than necessary. By substantially circular, we mean that in each meridian plane, between the last point of contact and a point on the external surface located radially between 0.2 times and 0.4 times RI, the external surface is located on a curve between two circles of radii varying by 10%.
[0020] Une solution préférée pour optimiser les contraintes au niveau de la jonction entre le flanc et le bourrelet est que, le pneumatique étant monté et gonflé sur la jante nominale, la partie la plus radialement intérieure de la surface externe du flanc est de forme sensiblement circulaire, suivant un cercle dont le centre est sur la droite passant par le centre de la partie circulaire du crochet de ladite jante et le dernier point de contact, et dont le rayon R2 est compris en 0.25 et 0.4 fois le rayon RI de la partie circulaire du crochet de ladite jante. [0020] A preferred solution for optimizing the stresses at the junction between the sidewall and the bead is that, the tire being mounted and inflated on the nominal rim, the most radially interior part of the external surface of the sidewall is of the shape substantially circular, following a circle whose center is on the right passing through the center of the circular part of the hook of said rim and the last point of contact, and whose radius R2 is included in 0.25 and 0.4 times the radius RI of the circular part of the hook of said rim.
[0021] Une solution avantageuse pour assurer la meilleure continuité de la surface externe du flanc notamment entre la partie circulaire la plus radialement intérieure et la partie qui lui est adjacente est que, le pneumatique étant monté et gonflé sur la jante nominale, la partie la plus radialement intérieure de la surface externe du flanc est de forme sensiblement circulaire sur une portion angulaire comprise entre 65° et 75° et mesurée depuis le rayon formé par le dernier point de contact et le centre du cercle. [0022] Pour optimiser la forme du flanc et notamment sa thermique, le pneumatique étant monté et gonflé sur la jante nominale, la surface externe du flanc radialement extérieure et adjacente à la partie sensiblement circulaire la plus radialement intérieure de la surface externe du flanc sur une hauteur radiale égale à la hauteur radiale G du crochet de la jante nominale, a un centre de courbure axial ement extérieur au bourrelet et de préférence un rayon de courbure moyen au moins égal à 400 mm. Dans les pneumatiques selon l’état de l’art, le centre de courbure de cette zone du flanc est axialement intérieur au bourrelet dans la continuité de la connexion entre le bourrelet et le flanc. L’invention demande la reconfiguration de l’ensemble de la zone pour lui assurer un fonctionnement correct. [0021] An advantageous solution for ensuring the best continuity of the external surface of the sidewall, particularly between the most radially interior circular part and the part adjacent to it, is that, the tire being mounted and inflated on the nominal rim, the part more radially interior of the external surface of the sidewall is of substantially circular shape over an angular portion between 65° and 75° and measured from the radius formed by the last point of contact and the center of the circle. [0022] To optimize the shape of the sidewall and in particular its thermal, the tire being mounted and inflated on the nominal rim, the outer surface of the sidewall radially outer and adjacent to the most radially inner substantially circular part of the outer surface of the sidewall on a radial height equal to the radial height G of the hook of the nominal rim, has a center of curvature axially external to the bead and preferably an average radius of curvature at least equal to 400 mm. In tires according to the state of the art, the center of curvature of this zone of the sidewall is axially inside the bead in the continuity of the connection between the bead and the sidewall. The invention requires the reconfiguration of the entire zone to ensure correct operation.
[0023] Cette reconfiguration du bourrelet et de la partie adjacente du flanc a pour conséquence de déplacer le point de compression du retournement de la couche de carcasse vers un point radialement extérieur comparativement à la solution de l’état de l’art. Ce point se situe par rapport au point le plus axialement extérieur du siège de la jante entre 2 et 2.5 fois la hauteur (G) du crochet de la jante. Pour minimiser la compression dans le retournement à cet endroit, il convient donc de rapprocher le retournement à la partie principale de la couche de carcasse. Comparativement à la solution selon l’état de l’art, réaliser ce rapprochement à ce niveau est beaucoup plus aisé, car on dispose d’une plus grande longueur de retournement pour réaliser ce rapprochement. Une solution préférée est donc que le pneumatique étant monté gonflé sur la jante nominale, la distance entre la partie principale de la couche de carcasse, et son retournement, est minimale à une hauteur radiale du point le plus axialement extérieur du siège de la jante nominale, comprise entre 2 et 2.5 fois la hauteur du crochet de la jante nominale. [0023] This reconfiguration of the bead and the adjacent part of the sidewall has the consequence of moving the compression point of the turning of the carcass layer towards a radially outer point compared to the state of the art solution. This point is located in relation to the most axially exterior point of the seat of the rim between 2 and 2.5 times the height (G) of the rim hook. To minimize the compression in the turning at this location, it is therefore advisable to bring the turning closer to the main part of the carcass layer. Compared to the solution according to the state of the art, making this connection at this level is much easier, because we have a greater turning length to make this connection. A preferred solution is therefore that the tire being mounted inflated on the nominal rim, the distance between the main part of the carcass layer, and its inversion, is minimal at a radial height from the most axially outer point of the seat of the nominal rim , between 2 and 2.5 times the height of the nominal rim hook.
[0024] La mesure de la distance entre la partie principale de la couche de carcasse, et son retournement pourra se faire sur une coupe méridienne. La distance est mesurée depuis la fibre neutre de la couche de carcasse jusqu’à la fibre neutre du retournement perpendiculairement à la fibre neutre de la partie principale de la couche de carcasse. [0025] Pour une bonne répartition de la rigidité dans le bourrelet, il est avantageux que la distance entre la partie principale de la couche de carcasse, et son retournement soit continûment décroissante depuis le centre géométrique de la tringle jusqu’au point du minimum de ladite distance. The measurement of the distance between the main part of the carcass layer, and its reversal can be done on a meridian section. The distance is measured from the neutral fiber of the carcass layer to the neutral fiber of the turnaround perpendicular to the neutral fiber of the main part of the carcass layer. [0025] For a good distribution of the rigidity in the bead, it is advantageous for the distance between the main part of the carcass layer and its reversal to be continuously decreasing from the geometric center of the bead to the point of the minimum of said distance.
[0026] Pour un fonctionnement optimal du bourrelet et du flanc, il est avantageux qu’une unique composition de caoutchouc, dit gomme de bourrage tringle, comble le volume entre la partie principale de la couche de carcasse, et son retournement, cette composition de caoutchouc ayant un module d’extension sécant MA10 à 10 % de déformation, mesuré à 23° C selon la norme ASTM D 412, au moins égal à 5 MPa. [0027] Pour éviter des gradients de déformation trop importants entre le bourrage tringle et la composition de caoutchouc enrobant les éléments de renforcement de la couche de carcasse, il est avantageux qu’une unique composition de caoutchouc comble le volume entre la partie principale de la couche de carcasse, et son retournement et ait un module d’extension sécant MA10 à 10 % de déformation, mesuré à 23° C selon la norme ASTM D 412, au moins égal à 90% et de préférence au plus égal à 110%, du même module de la composition de caoutchouc enrobant les éléments de renforcement de la couche de carcasse. [0028] De même pour un fonctionnement optimal en flexion du flanc, il est préféré qu’une composition de caoutchouc adjacent et axial ement extérieur au retournement de la couche de carcasse, au moins radial ement à l’extérieur audit dernier point de contact de la surface externe du bourrelet, ait un module d’extension sécant MA10 à 10 % de déformation, mesuré à 23° C selon la norme ASTM D 412, au moins égal à 90% et de préférence au plus égal à 110% du module d’extension MA10 du bourrage tringle. [0026] For optimal operation of the bead and the sidewall, it is advantageous for a single rubber composition, called a bead filler rubber, to fill the volume between the main part of the carcass layer, and its reversal, this composition of rubber having a secant extension modulus MA10 at 10% deformation, measured at 23° C according to standard ASTM D 412, at least equal to 5 MPa. [0027] To avoid excessively large deformation gradients between the bead filler and the rubber composition coating the reinforcing elements of the carcass layer, it is advantageous for a single rubber composition to fill the volume between the main part of the carcass layer, and its reversal and has a secant extension modulus MA10 at 10% deformation, measured at 23° C according to the ASTM D 412 standard, at least equal to 90% and preferably at most equal to 110%, of the same module of the rubber composition coating the reinforcing elements of the carcass layer. [0028] Likewise for optimal operation in bending of the sidewall, it is preferred that a rubber composition adjacent and axially external to the reversal of the carcass layer, at least radially external to said last point of contact of the external surface of the bead, has a secant extension modulus MA10 at 10% deformation, measured at 23° C according to standard ASTM D 412, at least equal to 90% and preferably at most equal to 110% of the modulus d MA10 rod filler extension.
[0029] Les caractéristiques de l’invention sont illustrées par les figures 1 à 3 schématiques et non représentées à l’échelle, en référence à un pneumatique de dimension 24.00R35. [0029] The characteristics of the invention are illustrated in Figures 1 to 3, which are schematic and not shown to scale, with reference to a tire of size 24.00R35.
[0030] Sur la figure 1, est représenté le contour d’une jante (1) de seat conique pour les pneumatiques de dimension 25, 29, 33, 35, 49, 51, 57 et 63 pouces tels que présenté dans la documentation de la « tyre and Rim association » (association du pneumatique et de la roue). Ce contour représente la coupe d’une jante comprenant de part et d’autre d’un plan médian perpendiculaire à l’axe de rotation (O Y) de ladite jante, un siège de jante conique (11) et un bord (12), d’une hauteur radiale G, formé axialement de l’intérieur vers l’extérieur d’une première partie radiale (121) et d’un crochet (122) formé par une première partie circulaire de rayon normé RI et de centre 01 (cf. figure. 2 et 3), et d’une fin de crochet. La figure montre également le point (111) le plus axialement extérieur du siège (11) de la jante sur la surface de contact avec le pneumatique. Dans le cas où le siège (11) de la jante nominale serait lié au bord (12) par un congé, le congé serait considéré comme le début du bord (12). [0030] In Figure 1, the outline of a conical seat rim (1) is shown for tires of dimensions 25, 29, 33, 35, 49, 51, 57 and 63 inches as presented in the documentation of the “tyre and Rim association” (association of tires and wheels). This contour represents the section of a rim comprising on either side of a median plane perpendicular to the axis of rotation (O Y) of said rim, a conical rim seat (11) and an edge (12), of a radial height G, formed axially from the inside towards the outside of a first radial part (121) and a hook (122) formed by a first circular part of standardized radius RI and center 01 (see . figure 2 and 3), and a hook end. The figure also shows the most axially outer point (111) of the seat (11) of the rim on the contact surface with the tire. In the case where the seat (11) of the nominal rim is linked to the edge (12) by a fillet, the fillet would be considered as the start of the edge (12).
[0031] La figure 2 montre le détail d’une coupe méridienne d’un pneumatique pour véhicule lourd de type génie civil monté, gonflé sur sa jante (1), et notamment le flanc (2), et le bourrelet (3). Le bourrelet (3) a une surface externe (31) se prolongeant par une surface externe du flanc (21). L’armature de carcasse radiale comprend une couche de carcasse (4) ancrée dans le bourrelet par un retournement autour d’une tringle (5), pour former une partie principale (41) s’étendant d’une tringle à l’autre, et un retournement (42), axialement extérieur à la partie principale (41) dans chacun des bourrelets (3), et ayant une extrémité libre (421). La surface externe (31) du bourrelet est configurée pour être en contact avec la jante nominale (1), jusqu’au point de contact (311) le plus radialement extérieur sur la partie circulaire de centre (01) du crochet de jante, l’angle (Al) entre le rayon de la partie circulaire de la jante passant par ledit dernier (311) point de contact et la direction axiale étant compris entre 80 et 85°. Conformément aux figures 2 et 3, l’angle (Al) entre le rayon de la partie circulaire de la jante passant par le dernier point de contact et la direction axiale, est déterminé depuis un point d’intersection de la jante avec l’axe axial jusqu’au dernier point de contact entre le crochet de jante et la surface externe du bourrelet. La figure 2 montre également la distance (d) entre la partie principale (41) de la couche de carcasse (4), et son retournement (42) qui est continûment décroissante jusqu’à son minimum (dm) situé à une hauteur radiale (hm) du point le plus axialement extérieur du siège (111) de la jante, comprise entre 2 et 2.5 fois la hauteur (G) du crochet de la jante. Une unique composition de caoutchouc, dit gomme de bourrage tringle (32), comble le volume entre la partie principale (41) de la couche de carcasse (4), et son retournement (42), adjacent et axialement intérieur à une composition (22) de caoutchouc. La figure 2 montre également le profil (21’) d’un pneumatique selon l’état de l’art. [0031] Figure 2 shows the detail of a meridian section of a tire for a heavy vehicle of the civil engineering type mounted, inflated on its rim (1), and in particular the sidewall (2), and the bead (3). The bead (3) has an external surface (31) extending by an external surface of the sidewall (21). The radial carcass reinforcement comprises a carcass layer (4) anchored in the bead by an inversion around a rod (5), to form a main part (41) extending from one rod to the other, and a turnaround (42), axially exterior to the main part (41) in each of the beads (3), and having a free end (421). The outer surface (31) of the bead is configured to be in contact with the nominal rim (1), up to the radially outermost contact point (311) on the central circular portion (01) of the rim hook, l 'corner (Al) between the radius of the circular part of the rim passing through said last (311) point of contact and the axial direction being between 80 and 85°. In accordance with Figures 2 and 3, the angle (Al) between the radius of the circular part of the rim passing through the last point of contact and the axial direction, is determined from a point of intersection of the rim with the axis axial to the last point of contact between the rim hook and the external surface of the bead. Figure 2 also shows the distance (d) between the main part (41) of the carcass layer (4), and its reversal (42) which is continuously decreasing until its minimum (dm) located at a radial height ( hm) from the most axially outer point of the seat (111) of the rim, between 2 and 2.5 times the height (G) of the rim hook. A single rubber composition, called a bead filler rubber (32), fills the volume between the main part (41) of the carcass layer (4), and its reversal (42), adjacent and axially interior to a composition (22). ) of rubber. Figure 2 also shows the profile (21') of a tire according to the state of the art.
[0032] La figure 3 est un zoom sur le bourrelet pour montrer la transition entre le bourrelet et le flanc autour du dernier point de contact (311) entre la surface externe (31) du bourrelet (3) et de la jante nominale (1). La surface externe (21) du flanc (2) est dans sa partie la plus radial ement intérieure (211) de forme sensiblement circulaire, suivant un cercle dont le centre (02) est sur la droite passant par le centre (01) de la partie circulaire du crochet (122) et le dernier point de contact (311), et dont le rayon R2 est compris en 0.25 et 0.4 fois le rayon RI de la partie circulaire du crochet (122) de ladite jante (1), sur une portion angulaire (A2) comprise entre 65 et 75° et mesurée depuis le rayon formé par le dernier point de contact (311) et le centre (02) du cercle. [0032] Figure 3 is a zoom on the bead to show the transition between the bead and the sidewall around the last point of contact (311) between the external surface (31) of the bead (3) and the nominal rim (1 ). The external surface (21) of the sidewall (2) is in its most radially interior part (211) of substantially circular shape, following a circle whose center (02) is on the straight line passing through the center (01) of the circular part of the hook (122) and the last point of contact (311), and whose radius R2 is included in 0.25 and 0.4 times the radius RI of the circular part of the hook (122) of said rim (1), on a angular portion (A2) between 65 and 75° and measured from the radius formed by the last point of contact (311) and the center (02) of the circle.
[0033] L’invention a été testée sur des pneumatiques de dimension 24.00R35. Les pneumatiques selon l’invention sont comparés à des pneumatiques de référence de même dimension. [0033] The invention was tested on tires of size 24.00R35. The tires according to the invention are compared to reference tires of the same size.
[0034] Les pneumatiques de référence et les pneumatiques selon l’invention comprennent une unique couche de carcasse dont les renforts métalliques sont des câbles de 7 torons comprenant 7 fils d’acier de 23 centièmes de 2.24 mm de diamètre disposés selon un pas de 2.6 mm sous la tringle. Les retournements pour les deux pneumatiques ont leurs extrémités libre (421) à proximité du point le plus axialement extérieur du pneumatique. Les compositions de caoutchouc utilisées sont équivalentes pour les deux solutions. La géométrie de la surface externe du bourrelet a été modifiée de telle sorte que le dernier point de contact (311) passe pour le pneumatique témoin d’un angle Al proche de 60° et à, pour le pneumatique selon l’invention, un angle égal à 81.3°. Pour le pneumatique témoin, le raccordement au point de contact se fait par une courbe sensiblement circulaire sur toute la partie du flanc comprise entre le dernier point de contact (311) et le point le plus axialement extérieur du pneumatique, courbe dont le centre de courbure est axialement intérieur au bourrelet. Pour le pneumatique selon l’invention, le raccordement entre le bourrelet et le flanc se fait par une portion circulaire sur une portion angulaire de 69°, le centre de cette portion angulaire se trouvant sur la droite prolongeant le rayon de la partie circulaire du crochet de jante passant par le dernier point de contact (311) entre la surface externe (31) du bourrelet (3) et la jante (1). Le rayon de cette partie circulaire est égal à 0.3 fois le rayon RI de la partie circulaire de la jante (1). La distance (d) entre la partie principale (41) de la couche de carcasse (4), et son retournement (42) est minimale à une hauteur radiale (hm) du point le plus axialement extérieur du siège (111) de la jante, égale à 2.1 fois la hauteur (G) du crochet de la jante pour l’invention contre 1.0 fois la hauteur (G) pour le pneumatique de référence. [0034] The reference tires and the tires according to the invention comprise a single layer of carcass whose metal reinforcements are cables of 7 strands comprising 7 steel wires of 23 hundredths of 2.24 mm in diameter arranged in a pitch of 2.6 mm under the rod. The turnarounds for both tires have their free ends (421) near the most axially outer point of the tire. The rubber compositions used are equivalent for both solutions. The geometry of the external surface of the bead has been modified such that the last point of contact (311) has an angle Al close to 60° for the control tire and, for the tire according to the invention, an angle equal to 81.3°. For the control tire, the connection to the point of contact is made by a substantially circular curve over the entire part of the sidewall between the last point of contact (311) and the most axially external point of the tire, curve whose center of curvature is axially interior to the bead. For the tire according to the invention, the connection between the bead and the sidewall is made by a circular portion over an angular portion of 69°, the center of this angular portion being on the right extending the radius of the circular part of the hook of rim passing through the last point of contact (311) between the external surface (31) of the bead (3) and the rim (1). The radius of this circular part is equal to 0.3 times the radius RI of the circular part of the rim (1). The distance (d) between the main part (41) of the carcass layer (4), and its turn (42) is minimum at a radial height (hm) of the most axially outer point of the seat (111) of the rim , equal to 2.1 times the height (G) of the rim hook for the invention against 1.0 times the height (G) for the reference tire.
[0035] Les autres composants des pneumatiques témoins et selon l’invention, architecture sommet, mélanges caoutchouteux. . . sont identiques. [0035] The other components of the control tires and according to the invention, crown architecture, rubber mixtures. . . are the same.
[0036] Les pneumatiques sont testés sur machine. Ils sont préalablement rabotés jusqu’au fond de sculpture afin de concentrer les sollicitations sur les flancs et les bourrelets. Le profil de la bande de roulement du pneumatique raboté correspondant au profil de la bande de roulement à neuf. Deux pneumatiques sont écrasés l’un sur l’autre avec un effort de 25 000 daN correspondant à la charge nominale plus 25% de surcharge à 6.2 bars de pression soit une pression inférieure de 1.05 bar à la pression nominale. Les pneumatiques roulent l’un sur l’autre à la vitesse de 15 km/h. Le pneumatique selon l’invention a effectué plus de 1000 h de roulage sans dommage quand le pneumatique selon l’état de l’art a été arrêté sur une cassure des mélanges de gomme dans le flanc, dans la partie adjacente au crochet de jante, au bout de 600h. [0036] The tires are tested on a machine. They are previously planed to the bottom of the sculpture in order to concentrate the stresses on the sides and the beads. The profile of the tread of the planed tire corresponding to the profile of the new tread. Two tires are crushed on top of each other with a force of 25,000 daN corresponding to the nominal load plus 25% overload at 6.2 bar pressure, i.e. a pressure 1.05 bar lower than the nominal pressure. The tires roll on top of each other at a speed of 15 km/h. The tire according to the invention performed more than 1000 hours of driving without damage when the tire according to the state of the art was stopped on a break in the rubber mixtures in the sidewall, in the part adjacent to the rim hook, after 600 hours.
[0037] Ainsi l’invention amène bien une amélioration d’au moins 66% de la performance en endurance du flanc et du bourrelet pour un usage surchargé et sous gonflé. [0037] Thus the invention provides an improvement of at least 66% in the endurance performance of the sidewall and the bead for overloaded and underinflated use.

Claims

REVENDICATIONS Pneumatique pour véhicule de type génie civil destiné à être monté sur une jante nominale (1), ladite jante nominale comprenant de part et d’autre d’un plan médian perpendiculaire à l’axe de rotation de ladite jante, un siège de jante conique (11) et un bord (12), d’hauteur radiale G, formé axialement de l’intérieur vers l’extérieur d’une première partie radiale (121) et d’un crochet (122) formé par une première partie circulaire de rayon normé RI et de centre 01, et d’une fin de crochet, le pneumatique comprenant : CLAIMS Tire for civil engineering type vehicle intended to be mounted on a nominal rim (1), said nominal rim comprising on either side of a median plane perpendicular to the axis of rotation of said rim, a rim seat conical (11) and an edge (12), of radial height G, formed axially from the inside towards the outside of a first radial part (121) and a hook (122) formed by a first circular part of standardized radius RI and center 01, and a hook end, the tire comprising:
• une armature de sommet, radialement intérieure à une bande de roulement, ladite bande de roulement étant réunie par l’intermédiaire de deux flancs (2), à deux bourrelets (3), • a crown reinforcement, radially internal to a tread, said tread being joined via two sidewalls (2), with two beads (3),
• chaque bourrelet (3) ayant une surface externe (31) se prolongeant par une surface externe du flanc (21), • each bead (3) having an external surface (31) extending by an external surface of the sidewall (21),
• une armature de carcasse radiale s’étendant entre les deux bourrelets et comprenant au moins une couche de carcasse (4) comportant des renforts métalliques formant un angle, avec une direction circonférentielle, compris entre 80° et 100°, enrobés par une composition de caoutchouc, ladite couche de carcasse (4) étant ancrée dans chacun des bourrelets par un retournement autour d’une tringle (5), pour former une partie principale (41) s’étendant d’une tringle à l’autre, et un retournement (42), axialement extérieur à la partie principale (41) dans chacun des bourrelets (3), et ayant une extrémité libre (421), • a radial carcass reinforcement extending between the two beads and comprising at least one carcass layer (4) comprising metal reinforcements forming an angle, with a circumferential direction, between 80° and 100°, coated with a composition of rubber, said carcass layer (4) being anchored in each of the beads by an inversion around a rod (5), to form a main part (41) extending from one rod to the other, and an inversion (42), axially exterior to the main part (41) in each of the beads (3), and having a free end (421),
• caractérisé en ce que la surface externe (31) du bourrelet est configurée dans chaque plan méridien, pour être en contact avec ladite jante nominale (1), la mesure étant faite sur un pneumatique monté et gonflé sur ladite jante nominale (1) à la pression nominale, sur le siège et le bord de la jante jusqu’à un dernier point (311) de contact à la partie circulaire du crochet de jante nominale, le dernier point (311) de contact étant le point de contact le plus radialement extérieur entre la jante nominale et le bourrelet, l’angle (Al) entre le rayon de la partie circulaire de la jante nominale passant par ledit dernier (311) point de contact et la direction axiale étant compris entre 80 et 85°. • characterized in that the external surface (31) of the bead is configured in each meridian plane, to be in contact with said nominal rim (1), the measurement being made on a tire mounted and inflated on said nominal rim (1) at the nominal pressure, on the seat and the edge of the rim to a last point (311) of contact at the circular part of the nominal rim hook, the last point (311) of contact being the most radially contact point exterior between the nominal rim and the bead, the angle (Al) between the radius of the circular part of the nominal rim passing through said last (311) point of contact and the axial direction being between 80 and 85°.
2. Pneumatique selon la revendication 1, dans lequel, sur les parties axial ement extérieures du bourrelet (3) et du flanc (2), la surface externe du bourrelet (31) est reliée à la surface externe du flanc (21) par une partie la plus radialement intérieure (211) de la surface externe du flanc (21), ladite partie la plus radialement intérieure (211) étant sensiblement circulaire sur une portion d’une hauteur radiale au moins égale à 0.2 fois RI et au plus égale à 0.4 fois RI le rayon du crochet de jante (122), le centre de courbure (02) de ladite partie (211) la plus radialement intérieure de la surface externe du flanc (21) étant axial ement intérieur à ladite partie la plus radialement intérieure (211) de la surface externe du flanc (21). 2. Tire according to claim 1, in which, on the axially outer parts of the bead (3) and the sidewall (2), the outer surface of the bead (31) is connected to the outer surface of the sidewall (21) by a most radially interior part (211) of the external surface of the sidewall (21), said most radially interior part (211) being substantially circular over a portion of a radial height at least equal to 0.2 times RI and at most equal to 0.4 times RI the radius of the rim hook (122), the center of curvature (02) of said most radially interior part (211) of the external surface of the sidewall (21) being axially interior to said most radially interior part (211) of the external surface of the sidewall (21).
3. Pneumatique selon la revendication 2, dans lequel la partie la plus radialement intérieure (211) de la surface externe (21) du flanc (2) est de forme sensiblement circulaire, suivant un cercle dont le centre (02) est sur la droite passant par le centre de la partie circulaire du crochet (122) de ladite jante (1) et le dernier point de contact (311), et dont le rayon R2 est compris en 0.25 et 0.4 fois le rayon RI de la partie circulaire du crochet (122) de ladite jante (1). 3. Tire according to claim 2, in which the most radially inner part (211) of the external surface (21) of the sidewall (2) is of substantially circular shape, following a circle whose center (02) is on the right passing through the center of the circular part of the hook (122) of said rim (1) and the last point of contact (311), and whose radius R2 is between 0.25 and 0.4 times the radius RI of the circular part of the hook (122) of said rim (1).
4. Pneumatique selon la revendication 3, dans lequel la partie la plus radialement intérieure (211) de la surface externe (21) du flanc (2) est de forme sensiblement circulaire sur une portion angulaire (A2) comprise entre 65° et 75° et mesurée depuis le rayon formé par le dernier point de contact (311) et le centre (02) du cercle. 4. Tire according to claim 3, in which the most radially inner part (211) of the external surface (21) of the sidewall (2) is of substantially circular shape on an angular portion (A2) between 65° and 75° and measured from the radius formed by the last contact point (311) and the center (02) of the circle.
5. Pneumatique selon l’une des revendications précédentes, dans lequel, la surface externe (21) du flanc (2) radialement extérieure et adjacente à la partie sensiblement circulaire la plus radialement intérieure (211) de la surface externe (21) du flanc (2) sur une hauteur radiale égale à la hauteur radiale G du crochet (122) de la jante nominale (1), a un centre de courbure axialement extérieur au bourrelet (3). 5. Tire according to one of the preceding claims, wherein, the outer surface (21) of the sidewall (2) radially outer and adjacent to the most radially inner substantially circular part (211) of the outer surface (21) of the sidewall (2) over a radial height equal to the radial height G of the hook (122) of the nominal rim (1), has a center of curvature axially external to the bead (3).
6. Pneumatique selon l’une des revendications précédentes, dans lequel la distance (d) entre la partie principale (41) de la couche de carcasse (4), et son retournement (42) est minimale à une hauteur radiale (hm) du point le plus axial ement extérieur du siège (111) de la jante nominale, comprise entre 2 et 2.5 fois la hauteur (G) du crochet de la jante nominale. Pneumatique selon l’une des revendications précédentes, dans lequel, la distance (d) entre la partie principale (41) de la couche de carcasse, et son retournement (42) est continûment décroissante depuis le centre géométrique de la tringle (5) jusqu’au point du minimum (dm) de ladite distance (d). Pneumatique selon l’une des revendications précédentes, dans lequel une unique composition de caoutchouc, dit gomme de bourrage tringle (32), comble le volume entre la partie principale (41) de la couche de carcasse (4), et son retournement (42), cette composition de caoutchouc ayant un module d’extension sécant MA10 à 10 % de déformation, mesuré à 23° C selon la norme ASTM D 412, au moins égal à 5 MPa. Pneumatique selon l’une des revendications précédentes, dans lequel une unique composition de caoutchouc (32) comble le volume entre la partie principale (41) de la couche de carcasse (4), et son retournement (42) et a un module d’extension sécant MA10 à 10 % de déformation, mesuré à 23° C selon la norme ASTM D 412, au moins égal à 90% et de préférence au plus égal à 110%, du même module de la composition de caoutchouc enrobant les éléments de renforcement de la couche de carcasse (4). Pneumatique selon Tune des revendications précédentes, dans lequel une composition (22) de caoutchouc adjacente et axial ement extérieure au retournement (42) de la couche de carcasse, agencée au moins radial ement à l’extérieur dudit dernier point de contact (311) de la surface externe du bourrelet, a un module d’extension sécant MA10 à 10 % de déformation, mesuré à 23° C selon la norme ASTM D 412, au moins égal à 90% et de préférence au plus égal à 110% du module d’extension MA10 de la gomme du bourrage tringle (32). 6. Tire according to one of the preceding claims, in which the distance (d) between the main part (41) of the carcass layer (4), and its reversal (42) is minimum at a radial height (hm) of the most axially outer point of the seat (111) of the nominal rim, between 2 and 2.5 times the height (G) of the hook of the nominal rim. Tire according to one of the preceding claims, in which, the distance (d) between the main part (41) of the carcass layer, and its reversal (42) is continuously decreasing from the geometric center of the bead (5) until 'at the point of the minimum (dm) of said distance (d). Tire according to one of the preceding claims, in which a single rubber composition, called bead packing rubber (32), fills the volume between the main part (41) of the carcass layer (4), and its reversal (42). ), this rubber composition having a secant extension modulus MA10 at 10% deformation, measured at 23° C. according to standard ASTM D 412, at least equal to 5 MPa. Tire according to one of the preceding claims, in which a single rubber composition (32) fills the volume between the main part (41) of the carcass layer (4), and its reversal (42) and has a modulus of secant extension MA10 at 10% deformation, measured at 23° C according to standard ASTM D 412, at least equal to 90% and preferably at most equal to 110%, of the same modulus of the rubber composition coating the reinforcing elements of the carcass layer (4). Tire according to one of the preceding claims, in which a rubber composition (22) adjacent and axially external to the reversal (42) of the carcass layer, arranged at least radially outside said last contact point (311) of the external surface of the bead, has a secant extension modulus MA10 at 10% deformation, measured at 23° C according to standard ASTM D 412, at least equal to 90% and preferably at most equal to 110% of the modulus d MA10 extension of the bead jam rubber (32).
PCT/EP2023/077541 2022-10-13 2023-10-05 Optimised architecture of a civil engineering-type tyre WO2024078955A1 (en)

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US5236031A (en) 1990-11-20 1993-08-17 Bridgestone Corporation Pneumatic radial tires for construction vehicle
JP2000006621A (en) * 1998-06-22 2000-01-11 Sumitomo Rubber Ind Ltd Pneumatic tire
WO2001081103A1 (en) * 2000-04-25 2001-11-01 Societe De Technologie Michelin Lightened tyre bead
EP3045327A1 (en) * 2015-01-13 2016-07-20 Sumitomo Rubber Industries Limited Tire

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5236031A (en) 1990-11-20 1993-08-17 Bridgestone Corporation Pneumatic radial tires for construction vehicle
JP2000006621A (en) * 1998-06-22 2000-01-11 Sumitomo Rubber Ind Ltd Pneumatic tire
WO2001081103A1 (en) * 2000-04-25 2001-11-01 Societe De Technologie Michelin Lightened tyre bead
EP3045327A1 (en) * 2015-01-13 2016-07-20 Sumitomo Rubber Industries Limited Tire

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