Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C15/00—Tyre beads, e.g. ply turn-up or overlap
  • B60C15/0009—Tyre beads, e.g. ply turn-up or overlap features of the carcass terminal portion
  • B60C15/0081—Tyre beads, e.g. ply turn-up or overlap features of the carcass terminal portion the carcass plies folded around or between more than one bead core
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C15/00—Tyre beads, e.g. ply turn-up or overlap
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C15/00—Tyre beads, e.g. ply turn-up or overlap
  • B60C15/04—Bead cores
  • B60C15/05—Bead cores multiple, i.e. with two or more cores in each bead
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C15/00—Tyre beads, e.g. ply turn-up or overlap
  • B60C15/06—Flipper strips, fillers, or chafing strips and reinforcing layers for the construction of the bead
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T152/00—Resilient tires and wheels
  • Y10T152/10—Tires, resilient
  • Y10T152/10495—Pneumatic tire or inner tube
  • Y10T152/10819—Characterized by the structure of the bead portion of the tire
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T152/00—Resilient tires and wheels
  • Y10T152/10—Tires, resilient
  • Y10T152/10495—Pneumatic tire or inner tube
  • Y10T152/10819—Characterized by the structure of the bead portion of the tire
  • Y10T152/10828—Chafer or sealing strips

Definitions

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

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

Applications Claiming Priority (3)

Publications (1)

Family

ID=9521739

Family Applications (1)

Country Status (10)

Families Citing this family (19)

Family Cites Families (16)

• 1998
  • 1998-01-12 FR FR9800291A patent/FR2773518A1/fr active Pending
  • 1998-12-16 EP EP98966350A patent/EP1047565A1/fr not_active Withdrawn
  • 1998-12-16 CN CN98813434A patent/CN1129532C/zh not_active Expired - Fee Related
  • 1998-12-16 BR BR9814586-0A patent/BR9814586A/pt not_active IP Right Cessation
  • 1998-12-16 JP JP2000527415A patent/JP4564653B2/ja not_active Expired - Fee Related
  • 1998-12-16 KR KR1020007007653A patent/KR100697969B1/ko not_active IP Right Cessation
  • 1998-12-16 CA CA002318333A patent/CA2318333C/fr not_active Expired - Fee Related
  • 1998-12-16 WO PCT/EP1998/008264 patent/WO1999034989A1/fr active IP Right Grant
  • 1998-12-16 RU RU2000121067/11A patent/RU2219073C2/ru not_active IP Right Cessation
• 2000
  • 2000-07-12 US US09/614,627 patent/US6463975B1/en not_active Expired - Fee Related

Non-Patent Citations (1)

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