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
  • B60C15/06—Flipper strips, fillers, or chafing strips and reinforcing layers for the construction of the 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
  • B60C15/0603—Flipper strips, fillers, or chafing strips and reinforcing layers for the construction of the bead characterised by features of the bead filler or apex
  • B60C15/0607—Flipper strips, fillers, or chafing strips and reinforcing layers for the construction of the bead characterised by features of the bead filler or apex comprising several parts, e.g. made of different rubbers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
  • B60C9/02—Carcasses
  • B60C2009/0269—Physical properties or dimensions of the carcass coating rubber
  • B60C2009/0276—Modulus; Hardness; Loss modulus or "tangens delta"
• • 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
  • B60C13/00—Tyre sidewalls; Protecting, decorating, marking, or the like, thereof
  • B60C13/04—Tyre sidewalls; Protecting, decorating, marking, or the like, thereof having annular inlays or covers, e.g. white sidewalls
  • B60C2013/045—Tyre sidewalls; Protecting, decorating, marking, or the like, thereof having annular inlays or covers, e.g. white sidewalls comprising different sidewall rubber layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C2200/00—Tyres specially adapted for particular applications
  • B60C2200/06—Tyres specially adapted for particular applications for heavy duty vehicles

Definitions

• the present invention relates to a radial tire for fitting a heavy vehicle type civil engineering. Although not limited to this type of application, the invention will be more particularly described with reference to a radial tire to be mounted on a dumper, vehicle for transporting quarried quarry materials or surface mines.
• the nominal diameter of the rim of such a tire within the meaning of the European Tire and Rim Technical Organization (ETRTO) standard, is at least 25 ".
• Equatorial plane the plane passing through the middle of the running surface of the tire and perpendicular to the axis of rotation of the tire.
• Ring direction means a direction perpendicular to the axis of rotation of the tire.
• Axial direction a direction parallel to the axis of rotation of the tire.
• Circumferential Direction a direction perpendicular to a meridian plane.
• Ring distance a distance measured perpendicular to the axis of rotation of the tire and from the axis of rotation of the tire.
• Axial distance means a distance measured parallel to the axis of rotation of the tire and from the equatorial plane.
• a tire comprises two beads, providing the mechanical connection between the tire and the rim on which it is mounted, the beads being joined respectively via two sidewalls to a tread, intended to come into contact with the tire. soil through a rolling surface.
• a radial tire more particularly comprises a reinforcing reinforcement, comprising a crown reinforcement, radially inner to the tread, and a carcass reinforcement, radially inner to the crown reinforcement.
• the carcass reinforcement of a radial tire for civil engineering heavy vehicle usually comprises at least one carcass reinforcement layer consisting of metal reinforcing elements coated with a polymeric coating material.
• the metal reinforcing elements are substantially parallel to each other and form, with the circumferential direction, an angle of between 85 ° and 95 °.
• the carcass reinforcement layer comprises a main carcass reinforcement part, connecting the two beads to each other and winding in each bead around a bead core.
• the bead core comprises a circumferential reinforcing element most often metal surrounded by at least one material, non-exhaustively, polymeric or textile.
• the winding of the carcass reinforcement layer around the bead core extends from the inside to the outside of the tire to form a carcass reinforcement upturn, comprising one end.
• the carcass reinforcement overturn, in each bead allows the anchoring of the carcass reinforcement layer to the bead core core.
• Each bead comprises a filler member extending radially outwardly the bead core.
• the filling element has, in any meridian plane, a substantially triangular section and consists of at least one polymeric filling material.
• the filling element may consist of a stack in the radial direction of at least two polymeric filler materials in contact along a contact surface intersecting any meridian plane according to a meridian trace.
• the filler element axially separates the main carcass reinforcement portion and the carcass reinforcement upturn.
• Each bead also comprises a protective element extending radially inwards the flank and axially outside the carcass reinforcement overturning.
• the protection element is also at least partly in contact with its axially outer face with the edge of the rim.
• the protective element consists of at least one polymeric protective material.
• Each bead finally comprises an axially inner stuffing element to the sidewall and the protective element and axially outside the
• the stuffing element consists of at least one polymeric stuffing material.
• a polymeric material is mechanically characterized by tensile stress-strain characteristics determined by tensile tests. These tensile tests are carried out by a person skilled in the art on a test piece, according to a known method, for example in accordance with the international standard ISO 37, and under the normal conditions of temperature (23 + or - 2 ° C.) and hygrometry (50 + or -5% relative humidity), defined by the international standard ISO 471.
• a modulus of elasticity at 10% elongation of a polymeric mixture, expressed in mega pascals (MPa) is called the tensile stress measured for an elongation of 10% of F specimen.
• a polymeric material, after cooking, is also characterized mechanically by its hardness.
• the hardness is defined in particular by the Shore A hardness determined in accordance with ASTM D 2240-86.
• the bending cycles in particular lead to stresses and deformations mainly of shear and compression, in the polymeric coating and stuffing materials, on the axially outer face of the carcass reinforcement upturn, due to the flexion bead on the rim flange.
• the bending cycles initiate cracks on the axially outer face of the carcass reinforcement overturn. These cracks propagate in the polymeric coating material and then in the polymeric stuffing material in which they form cavities likely to cause, over time, degradation of the tire requiring replacement.
• the crack propagation velocity depends on the one hand on the amplitude and the frequency of the stress and deformation cycles, on the other hand on the stiffnesses of the polymeric materials, in the cracking zone.
• JP 2004345414 has already described, in the case of a radial carcass reinforcement tire, beads whose design is intended to prevent cracks generated in the overlap zone between the carcass reinforcement overturning. and the radially outer end of a layer of metal reinforcing elements surrounding the radially inner portion of the bead core.
• a polymeric material element is interposed between the carcass reinforcement upturn and the radially outer end of the layer of metal reinforcing elements surrounding the radially inner portion of the bead core.
• the inventors have set themselves the objective of improving the endurance of the beads of a radial tire for a heavy vehicle type civil engineering, by reducing the speed of propagation of cracks that are initiated on the face externally of the carcass reinforcement overturn and propagate through the polymeric encapsulating and stuffing materials.
• a tire for a heavy vehicle of the civil engineering type comprising two beads intended to come into contact with a rim comprising two at least partly circular rims of rim,
• a carcass reinforcement comprising at least one carcass reinforcement layer consisting of metal reinforcing elements coated with a polymeric coating material
• the carcass reinforcement layer comprising a main carcass reinforcement part wound in each bead, from the inside to the outside of the tire, around a bead core to form a carcass reinforcement overturning ,
• each bead comprising a protection element radially inwardly extending a flank and a stuffing element axially inside the protection element and at the flank and axially outside the carcass reinforcement overturning,
• protection and stuffing elements being constituted respectively of at least one polymeric protective material and a polymeric stuffing material
• the polymeric stuffing material having a modulus of elasticity at 10% elongation less than the modulus of elasticity at 10% elongation of the polymeric coating material
• a transition element consisting of a transition polymeric material, being in contact, by its axially inner face, with the polymeric coating material of the axially outer face of the carcass reinforcement upturn and, by its axially facing side; outside, with the polymeric stuffing material,
• the modulus of elasticity at 10% of elongation of the polymeric transition material being intermediate between the elastic modulus at 10% elongation respective polymeric coating material and polymeric stuffing material.
• a transition element consisting of a polymeric transition material, in contact, by its axially inner face, with the polymeric coating material of the axially outer face of the carcass reinforcement reversal and, by its axially outer face, with the polymeric stuffing material.
• a transition element makes it possible to achieve a stiffness gradient and locally limit the levels of stresses and strains on which depends the crack propagation rate initiated on the axially outer face of the frame reinforcement. carcass and propagating through the polymeric coating and stuffing materials.
• the modulus of elasticity at 10% elongation of the transition polymeric material is advantageously intermediate between the elastic moduli at 10% elongation respective of the polymeric coating material and the polymeric stuffing material with which the transition element is in contact.
• transition polymer then to the polymeric stuffing material allows a decreasing and progressive gradient of stiffness, which reduces the stresses and deformations on the axially outer face of the carcass reinforcement overturn and, therefore, to slow the propagation of cracks .
• a modulus of elasticity at 10%> elongation of the intermediate transition polymeric material provides an advantage all the more significant as the difference between the respective elasticity modulus at 10%> elongation of the polymeric material.
• coating and polymeric stuffing material is important.
• the elastic modulus at 10% elongation of the polymeric coating material is equal to 1.6 times the modulus of elasticity at 10% elongation of the polymeric material. stuffing.
• the radially outer end of the radially outer transition element to the right passing through the center of the rim flange circle and making an angle of + 70 ° with respect to the axial direction.
• the rim of a tire comprising two rim flanges
• each rim flange comprising in its radially outermost part a circular portion, defining, for each rim flange, a local coordinate system whose origin is the center of the circle of the rim flange and whose axes are two straight lines passing through the center of the circle of the rim flange and respectively axially oriented towards the inside of the tire and radially outwardly of the tire.
• the angle of a straight line passing through the center of the rim flange circle with respect to the axial direction is the angle of this straight line with the axial direction line passing through the center of the circle of the rim flange and oriented towards the inside of the tire.
• This angle is positive if one passes from the straight line passing through the center of the circle of the rim flange and axially oriented towards the inside of the tire at said right by a rotation of trigonometric direction.
• the geometrical positions of the ends of the transition element are measured on a tire mounted on its rim, that is to say, inflated to the minimum pressure ensuring the correct positioning of the beads of the tire relative to the rim flanges .
• this minimum pressure may be equal to 10% of the nominal inflation pressure as specified by the ETRTO standard.
• the transition element must at least cover this crack sensitivity zone on the axially outer face of the carcass reinforcement upturn, taking into account the positioning tolerances of the transition element with respect to the upturn of the carcass reinforcement. carcass reinforcement inherent in the manufacturing process.
• the thickness of the transition element is at least equal to the thickness of the polymeric coating material.
• the thickness of the transition element is referred to as the constant thickness of the transition element measured outside the effusion zones at the ends of the transition element.
• the thickness of the polymeric coating material the thickness of the polymeric coating material measured on the axially outer face of the carcass reinforcement overturning, from and perpendicularly to the axially outer generatrix of a cylindrical element for reinforcing metal carcass reinforcement overturning.
• This minimum thickness of the transition element makes it possible to establish a minimum stiffness gradient, making it possible to reduce the speed of propagation of the cracks.
• the thickness of the transition element is advantageously at most equal to 5 times the thickness of the polymeric coating material. Indeed, the heat dissipation of the polymeric transition material is greater than that of the polymeric stuffing material, due to its modulus of elasticity at 10% higher elongation. Therefore, a too high volume of polymeric transition material causes a rise in temperature of the bead damaging to its duration of life, hence the importance of limiting the thickness of the transition element to a maximum value.
• An advantageous embodiment of the invention is to have the modulus of elasticity at 10% elongation of the polymeric transition material at least equal to 0.9 times and at most 1.1 times the arithmetic average of the moduli. respective elongation at 10% elongation of the polymeric coating material and the polymeric stuffing material.
• This range of values for the modulus of elasticity at 10% elongation of the transition polymeric material ensures a minimum stiffness gradient, when one passes successively from the polymeric coating material, to the polymeric transition material and then to the polymeric stuffing material. , therefore a significant decrease in the crack propagation speed.
• FIG 1 shows a sectional view in a meridian plane of the bead of a tire for a heavy vehicle of the civil engineering type of the state of the art.
• FIG. 2 shows a sectional view in a meridian plane of the bead of a tire for a heavy vehicle of the civil engineering type, according to the invention.
• FIGS 1 and 2 are not shown in scale for ease of understanding.
• a carcass reinforcement comprising a single carcass reinforcement layer consisting of metal reinforcing elements coated with a polymeric coating material, with a main carcass reinforcement part winding it, from the inside towards the outside of the tire, around a bead core 2 to form a carcass reinforcement upturn 1b,
• a filling element 3 extending radially outwardly the bead core 2, having, in any meridian plane, a substantially triangular section and consisting of two polymeric filler materials, a first polymeric filling material 3a being radially external and in contact with the bead core 2,
• a second polymeric filling material 3b being radially external and in contact with the first polymeric filling material 3a
• a protective element 4 extending radially inwardly a flank 5 and constituted by at least one polymeric protective material
• FIG. 2 shows a tire bead for a heavy vehicle of the civil engineering type, according to the invention, comprising:
• a carcass reinforcement comprising a single carcass reinforcement layer constituted by metal reinforcing elements coated with a polymeric coating material, with a carcass reinforcement main portion 21a winding, from the inside towards the outside of the tire, around a bead core 22 to form a carcass reinforcement upturn 21b,
• a filling element 23 extending radially outwardly the bead core 22, having, in any meridian plane, a substantially triangular section and consisting of two polymeric filling materials,
• a protective element 24 extending radially inwardly a sidewall 25 made of at least one protective polymeric material
• a stuffing element 26 axially inner to the protection element 24 and to the sidewall 25 and axially outside the carcass reinforcement overturning 21b, and consisting of a polymeric stuffing material.
• transition element 28 in contact, by its axially inner face, with the polymeric coating material of the axially outer face of the upturn carcass reinforcement and, by its axially outer face, with the polymeric stuffing material.
• the transition element 28 has a thickness e, represented
• the respective geometrical positioning of the radially outer ends E and radially inner I of the transition element 28 is defined relative to the local coordinate system whose origin is the center O of the rim flange circle 27 and whose axes YY and ZZ 'are two straight lines passing through the center O of the circle of the rim flange and respectively axially oriented towards the inside of the tire and radially outwardly of the tire.
• the angle of a straight line passing through the center O of the circle of the rim flange is then positive if one passes from the axis YY 'to the right by a rotation of trigonometric direction.
• the radially outer ends E and radially inner I of the transition element 28 are located respectively on the straight lines D and D, making the angles A and A with the axis YY '.
• the radially outer ends E and radially inner I of the transition element 28 are respectively radially external to the straight line Dmin, forming an angle with respect to the axis YY 'equal to + 70 °, and radially inner to the right d max , making an angle relative to the axis YY 'equal to + 40 °.
• the invention has been more particularly studied in the case of a heavy vehicle tire type dumper 59 / 80R63 dimension.
• the nominal conditions of use of such a tire are an inflation pressure equal to 6 bars, a static load equal to 99 tons and a distance covered in one hour between 16 and 32 km.
• the tire 59 / 80R63 was designed in accordance with the invention, as shown in FIG. 2.
• the angle A of the straight line D passing through the radially outer end E of the transition element 28 is equal to + 80 °, therefore greater than + 70 °.
• the angle a of the straight line passing through the radially inner end I of the transition element 28 is equal to + 35 °, therefore less than + 40 °.
• the thickness e of the transition element 28 is equal to 1.5 mm, so is between the thickness of the polymeric coating material equal to 1 mm and 5 times the thickness of the polymeric coating material.
• transition and packing polymers are respectively equal to 6 MPa, 4.8 MPa and 3.5 MPa. Therefore, the modulus of elasticity at 10% elongation of the transition polymeric material is equal to the arithmetic mean of the respective elongation moduli at 10% elongation of the encapsulating and stuffing polymeric materials.
• the elongation of the polymeric stuffing material 6, in the zone of sensitivity to cracking on the axially outer face of the carcass reinforcement upturn lb is equal to 1.3 times the elongation of the polymeric coating material in contact, these elongations being parallel to the carcass reinforcement overturn.
• the elongation of the polymeric transition material 28, in the zone of sensitivity to cracking on the axially outer face of the carcass reinforcement upturn 21b is equal to 1.1 times the elongation of the material polymeric coating.
• the propagation velocity of a crack of the polymeric coating material to the polymeric transition material 28, in the case of the invention is lower than the propagation speed of a crack of the polymeric material of the invention.
• coating to the polymeric stuffing material 6, in the case of the reference tire since the ratio of the elongation of the polymeric transition material 28 to the elongation of the polymeric material of coating, equal to 1.1, is less than the ratio of the elongation of the polymeric stuffing material 6 with respect to the elongation of the polymeric coating material, equal to 1.3.
• the invention should not be interpreted as being limited to the example illustrated in FIG. 2 but can be extended to other variants, such as, for example and in a non-exhaustive manner, relating to the number of polymeric transition materials between the polymeric coating material and the polymeric stuffing material.

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

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Citations (4)

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• 2009
  • 2009-12-09 FR FR0958781A patent/FR2953459B1/fr not_active Expired - Fee Related
• 2010
  • 2010-12-07 CA CA 2782726 patent/CA2782726A1/fr not_active Abandoned
  • 2010-12-07 WO PCT/EP2010/069077 patent/WO2011070018A1/fr active Application Filing
  • 2010-12-07 BR BR112012012896-5A patent/BR112012012896B1/pt active IP Right Grant
  • 2010-12-07 EP EP10787762.3A patent/EP2509807B1/fr active Active
  • 2010-12-07 CN CN201080055678.XA patent/CN102770288B/zh active Active
  • 2010-12-07 EA EA201290475A patent/EA021276B1/ru not_active IP Right Cessation
  • 2010-12-07 JP JP2012542518A patent/JP5732068B2/ja not_active Expired - Fee Related
  • 2010-12-07 ES ES10787762.3T patent/ES2546061T3/es active Active
  • 2010-12-07 US US13/515,260 patent/US20120298277A1/en not_active Abandoned
  • 2010-12-07 AU AU2010330021A patent/AU2010330021C1/en not_active Ceased
• 2012
  • 2012-05-16 ZA ZA2012/03573A patent/ZA201203573B/en unknown
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