MXPA00006853A - Tyre bead with circumferential reinforcing elements - Google Patents

Abstract

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

Description

PNEUMATIC HEEL WITH CIRCUMFERENTIAL REINFORCEMENT ELEMENTS DESCRIPTION OF THE INVENTION The present invention relates to a radial carcass reinforcement tire intended to carry heavy loads and, more particularly, to a tire for heavy goods vehicles, intended to equip vehicles such as, for example, trucks, road tractors, buses, trailers and others and, more particularly, to the new reinforcing structure of the heels of the aforementioned tires. A tire of the type considered comprises, in general, a carcass reinforcement formed by at least one wire rope fabric, anchored in each bead, at least to a rod, forming a fold. The carcass reinforcement has radially superimposed a crown reinforcement, composed of at least two metallic wire fabrics, crossed from one fabric to the next, forming with the circumferential direction angles comprised between 10 ° and 45 °. The folds of the carcass reinforcement are generally reinforced by at least one bead reinforcement fabric formed REF.121725 by metal cables oriented at a small angle, with respect to the circumferential direction, generally comprised between 10 ° and 30 °. The heel reinforcement fabric is generally located axially to the outside, along the fold of the carcass reinforcement, with a radially upper end located above or below the radially upper end of the fold of the carcass reinforcement . As regards the radially inferior end of such a reinforcing fabric, it is generally located below a line parallel to the axis of rotation and passing approximately through the center of gravity of the meridian section of the rod, anchor of the carcass reinforcement. The object of the known solution is to prevent the deradialization of the cables of the fold of the carcass reinforcement, as well as to minimize the radial and circumferential deformations suffered by the end of said fold, and by the outer rubber layer covering the bead and ensures the union with the rim. The useful life of the tires for large-tonnage vehicles, due to the progress made, due to the fact that certain taxiings become less penalizing in terms of wear of the tread, has become such that it is still necessary improve the resistance of the heels. Said improvement should fall on the degradation of the rubber layers at the ends of the fold of the carcass reinforcement and of the radially outer ends of the reinforcement fabrics of the heels. More particularly, in the case of tires subjected to prolonged rolling, which often induce a high temperature in the beads, due to the temperatures reached by the mounting rims, the rubber mixtures in contact with the rim are subjected, then, to a decrease of its rigidity, as well as to a more or less slow oxidation, which gives rise to a very marked tendency of the carcass reinforcement to unwind around the rod under the effect of the internal inflation pressure , despite the presence of one or more reinforcing fabrics of the heels. There are then movements of the rod, and shear deformations at all ends of the fabrics, which lead to the destruction of the heel. The mentioned improvement must refer, also, and mainly, to this second possibility of degradation.

To improve the strength of the heel area of a tire carrying large loads, U.S. Pat. do not. 3 301 303, claims a carcass reinforcement wound according to a precise pattern around two practically axially adjacent bead rods: the carcass reinforcement is first anchored by winding around the rod axially further to the interior going radially from the exterior to the interior, and then axially from inside to outside, to pass then radially below the second rod, axially disposed to the outside, to wind around said second rod going radially from the interior to the exterior and then axially from the exterior to the interior to form a fold that returns radially below the first. rod and which, eventually, is wound around said rod and then placed along the axially outer face of the carcass ply. The carcass reinforcement of a radial tire, mounted on its service rim and inflated to the recommended pressure, has, on one side, a meridian profile regularly convex between, approximately, the splice areas, on the one hand, with the meridian profile of the crown armor and, on the other hand, with the heel. In particular, from the radius in which the carcass reinforcement is influenced by the reinforcing webs of the heels, said reinforcement has, in the heel, a meridian profile, substantially rectilinear, or curved in the opposite direction to the curvature on the sides, i.e., substantially parallel to the curvature of the flanges of the rim from the inflection point situated radially, approximately, at the radially superior end of the heel reinforcement fabric placed along the bend of the rim. carcass armor. Such an arrangement, which associates two rods in a heel with a meridian profile that presents a point of inflection in the region of the heel, significantly improves the resistance of the heels in the case of taxiing in a hot rim, but, however, it becomes insufficient, in the case of a taxi in which the loads supported become higher, or the inflation pressures lower, at the recommended loads and pressures and, more particularly, when the relation between the height H on the rim and the maximum width S of the tire becomes less than 0.8. The investigations carried out by the applicant have led to the conclusion that the meridian profile of the carcass reinforcement in the region of the change of curvature in the bead should be reinforced by at least one bead reinforcement reinforcement. In order to improve the strength of the heels of a tire with an H / S aspect ratio of less than 0.8, intended to equip a vehicle carrying heavy loads, said tire, according to the invention, comprises at least one armor. of radial carcass, formed by at least one fabric of inextensible reinforcing elements, anchored in each bead B, at least, to two rods close to each other, folded around the first one and then wound around the second to form a fold, and is characterized in that, seen in meridian section, an additional reinforcement reinforcement formed by at least one fabric of circumferential reinforcing elements, is positioned along the carcass reinforcement, at least axially to the interior, in the region of the heel where the tracing of the meridian profile of said carcass reinforcement changes curvature, to become rectilinear or concave, up to the point of tangency T with the covering layer, ca if circular, of the first anchoring rod, said reinforcing reinforcement having its radially lower end radially below the line D parallel to the axis of rotation and passing through the point, of the covering layer of the first anchor rod , radially furthest from the axis of rotation, but above the line D, parallel to the axis of rotation and passing through the point, of the covering layer of the first anchor rod, radially closer to the axis of rotation. The additional reinforcement reinforcement will preferably have its radially upper end located at a radial distance from the line D, comprised between a magnitude equal to the radial distance between the straight lines D and D "increased in the radial half-distance between the straight lines D and D and a magnitude equal to the radial half-distance between lines D and D "decreased in the radial half-distance between lines D and D, with line D being the one with the greatest axial width, and line D" with the largest axial width., by definition, the line parallel to the axis of rotation and passing through the point of the meridian profile of the carcass reinforcement corresponding to the point of greatest 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 reinforcement are called circumferential, if the angle they form with the circumferential direction is between + 5 ° and -5 °. Whatever the path traveled by the carcass reinforcement for its anchoring to the two bead rods, for example, the tracing as described in U.S. Pat. do not. 3 301 303 and defined above, or a path defined, then, by a first bend around the axially innermost rod going from the inside to the outside and then a passage axially between the two rods to be radially above the rod axially more outside, bending around said rod going radially from top to bottom and axially from outside to inside, and then being radially below the rod further in, it is advantageous that the end of the bend is located radially below the rod axially more inside An advantageous modification of the bead thus obtained resides in the fact that the line joining the two centers of gravity of the cross sections of the rods is not parallel to the axis of rotation, but forms with the latter an open, axial and radially outward, between 20 ° and 60 °. This structure thus allows a partial absorption of the meridian tension stresses suffered by the carcass reinforcement, and minimizes the possible deformations of the bending of the carcass reinforcement, whatever the rolling conditions e. The absorption of the stresses will be greater the more numerous the reinforcing elements of the additional fabric are; these will be, preferably, metallic, steel, and will be together over the entire length of the reinforcing fabric. It is said that the reinforcing elements are together, if, in the direction perpendicular to said elements, the distance separating two adjacent elements is reduced to the maximum. The absorption of the stresses of the meridian tension of a carcass reinforcement is known per se from numerous documents. The French patent no. 750 726 of the applicant teaches the gluing of carcass reinforcement fabrics to auxiliary reinforcements, each formed by spirally wound yarn and which, consequently, exhibits remarkable flexibility in the transverse direction. Said gluing is carried out in such a way that two fabrics of the carcass reinforcement enclose an auxiliary reinforcement, said enclosure being made in the absence of a rod and a bending of the carcass reinforcement. The French patent no. 1 169 474 teaches, also to suppress the rod used, usually, by small fabrics of wires or metallic cables inclined on the anchoring parallel, the inclination angle being able to descend up to 5 °, being bent, or not, the fabric or the fabrics of the carcass weave. The French patent no. 1 234 995 provides for the replacement of the reinforcing elements, usually oblique, of the fabric or the heel reinforcement fabrics intended to reduce the movements of the anchor against the rim flange, by circumferential elements, the reinforcing reinforcement being able to be arranged between the main part of the carcass reinforcement and the bending of said reinforcement, or axially to the exterior of said carcass reinforcement bending. In the French patent no. 1 256 432, there are the same heel reinforcement structures, of circumferential elements, said elements being intended for the absorption, in their entirety, of the stresses of the carcass reinforcement, and in the case of tires for vehicles of tourism, in the absence of anchor rods or any other reinforcing fabric. Document FR 2 055 988 describes a certain number of possible applications of a bead reinforcement reinforcement, of circumferential elements, in particular, the use of such a reinforcement instead of the usual reinforcement of oblique elements arranged axially outside the bending of the carcass reinforcement. The resistance problems cited above and that are influenced by the operating temperature of the beads have been resolved, to a very small extent, by a so-called thinned bead structure, obtained, for example, by the means described in French patent no. 2 451 016, which teaches, for this purpose, to rely on the outer wall of the tire, comprised between the point where said wall leaves contact with the rim and the point at which said wall reaches its maximum distance with respect to the Equatorial plane, a relatively large concavity, when the tire is mounted on its service tire and inflated to the recommended pressure.

The carcass reinforcement, in order to reduce as much as possible the volume of the heels, is advantageously formed by reinforcing elements of textile material, which allows the reinforcement of the reinforcement to be easily carried out around the rods. However, for different reasons, the presence of a metal shell reinforcement is required, in particular, in the regions of the crown and the sides of the tire. A preferred solution of the invention then consists in providing said tire with a three-part carcass reinforcement: a first part of metallic reinforcing elements passing, at least, under the crown reinforcement and on the sides, and two other parts, formed by textile reinforcement elements, folded and wound around the two anchoring rods of each bead. The edges of the metal part, which part may or may not be bent around the anchoring rods, have, with the axially inner edges of the textile parts, a common overlap length, located, at least, in the region where the metal is located. additional reinforcement of circumferential reinforcement elements. The resistance of the heels, according to the invention, can also be improved by a thinning of said heels, conferring to the carcass reinforcement anchored to two rods in a heel, a meridian profile that does not present change of curvature in the heel. heels region. Said meridian profile is characterized, then, because, seen in meridian section, its tracing, comprised between the point A of greatest axial width and the point of tangency T with the coating layer, almost circular, of the first anchor rod, it is convex and circular over its entire length, the center of curvature being located on the line D "of greatest axial width, such that the thickness e of the heel B, measured perpendicular to said meridian profile at a point C of height hc, between 30 and 40 mm, measured with respect to the heel base YY ', is between 2 and 2.5 times the thickness e of the side measured on line D "of greatest axial width. The combination of the presence of two bead anchoring rods, with the presence of a bead reinforcement reinforcement, of circumferential elements, and arranged, according to the invention, inside the main part of the carcass reinforcement, allows not only the improvement of the resistance of the heels, but also, in combination with the fully convex meridian profile of the carcass reinforcement described above, allows to obtain a very clear decrease in the weight of a tire, without altering, on the other hand , His properties. Said decrease in weight can be advantageously accentuated by the replacement of the rods of rectangular metal wires used, generally, in the type of tire considered, by cheaper rods of the "braided" type, that is to say, formed by a helical braid of various metallic threads, or by "package" type rods, of polygonal section, that is, rods obtained by winding on a wire form, giving rise to several layers of different widths. The above types of rods, in addition, allow a smaller volume, due to the shape of their cross sections and the possible decrease of the aforementioned sections, respectively, of the order of 30% and 50% for each, which it leads, with respect to the application of the invention to the case of more bulky rectangular wire rods, to have a thinner bead thickness. The bead reinforcement reinforcement, thus described, can be made separately, by spirally winding it on a horizontal support in an appropriate manner and then transferring it to the unvulcanized tire blank. However, the manufacture of such a tire will advantageously be facilitated by the use of reinforcing elements, sections, or sets or groups of sections., of cables of circumferential length comprised between 0.2 and 0.4 times the average circumferential length of the reinforcement reinforcement, which allows, without major difficulties, the placement of the reinforcement reinforcement of the bead on the drum of preparation of the raw blank of the carcass reinforcement and the toric conformation of said blank, and the aforementioned average length being measured during the positioning on said confection drum. The interstices or circumferential cuts between cut elements will preferably be displaced relative to one another. The characteristics of the invention will be better understood with the help of the description that follows and which refers to the attached drawings, which illustrate, by way of non-limiting example, examples of execution, and in which: Figure 1 schematically represents a structure of pneumatic, known from the state of the art, figure 2 schematically represents, and in enlarged view, a first variant bead according to the invention, in its normal version, figure 3 schematically represents a second variant bead according to the invention, the rods being braided rods and the heel being thinned, FIG. 4 schematically represents a variant of the invention with a three-part carcass reinforcement. The tire P shown in FIG. 1 is a tire of measures 205/75 R 17.5 intended to be mounted on a rim comprising inclined rim seats 15 A The pneumatic tire comprises a tread band (4) joined to two heels B by intermediate of two sides (5). Each bead B is reinforced by a rod (1) formed by the winding on an appropriate form of a wire of quadrilateral section, until obtaining several rows of radially juxtaposed threads. Around said rod (1) is anchored a carcass reinforcement (2), composed of a single cable fabric of aromatic polyamide. The carcass reinforcement (2), seen in meridian section, has a meridian profile between the point A of greatest axial width and the point of tangency T of said profile with the coating layer (10), almost circular, of the rod ( 1) (it is said to be almost circular because the coating layer almost never has a perfectly circular transverse shape), which has two curvatures: the profile is convex from point A to point J of inflection located radially above the rod, and is concave from the point of inflection to point T of tangency. The anchor of the carcass reinforcement (2) is made by a fold (20) around the layer (10) of rubber mixture covering the rod (1), and the radial distance h separating the radially superior end of the rod (1). cited bending (20) with respect to the line YY '(parallel to the axis of rotation and defining the nominal diameter of the bead, which, in the present case, is also that of the rim), equal to 25 mm, in the example studied tire measures 205/75 R 17.5. Between the carcass reinforcement (2) and its bending (20), a rod filling (71) of rubber mixture of generally high Shore hardness is disposed radially above the rod (1). Axially to the outside of the fold (20), there is a reinforcing fabric (6) formed by inextensible metallic cables weakly oriented with respect to the circumferential direction and whose radially upper end is farther from the axis of rotation than the upper end of the fold ( 20) of the carcass reinforcement (2). Said fabric (6) is separated, on the one hand, from the carcass reinforcement (2), and from the rod filling (71) by a second blocking filler (72) and, on the other hand, from the rubber mixture. of protection (8) surrounding the heel, by a third padding (73). The heel B of the tire of measures 205/75 R 17.5, according to the invention and shown in figure 2, is reinforced by two rods (11) and (12), each of said cords being rectangular wire rods, that is, formed by winding on an appropriate form of a yarn of rectangular section, until obtaining several rows of radially juxtaposed yarns, which are covered by a rubber mixture (110) (120) of high elongation module. The line joining the two centers of gravity of the cross sections of the rods (11) and (12) forms with the axis of rotation an angle ß, open axially and radially to the outside, equal to 26 °. In the case described, the carcass reinforcement (2) is formed by a single fabric (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 to the almost circular coating layer (110) of the first rod (11) axially and radially further to the interior, to be rolled up next around said rod (11) going radially from outside to inside and axially from inside to outside, then extending to the second rod (12), and winding around said rod (12) going radially from inside to outside and axially from outside to inside and, finally, radially from outside to inside to go to join the first rod (11) axially to the outside and have its end radially below said first rod (11). The arrangement of the rubber fillers between the different reinforcement elements is modified, then, as follows: axially and radially to the outside of the axially inner rod (11) is a first filler (71), axially and radially to the outside of the axially external rod is a second filler (72), while radially and axially to the interior of the axially outer rod (12) is a third filler (73). Said arrangement can be modified in the sense that the complex formed by the axially outer rod (12) surrounded by the covering (120) and the filling (73) can be replaced by a single rubber filling (73). It is advantageous, then, that the secant modulus of elasticity to the stress of said single filler is high: measured for a relative elongation of 1%, this module is preferably at least equal to 10 MPa. The meridian profile of the carcass reinforcement (2) is, in a known manner, convex between the point A of greater axial width and the point of tangency T to the coating (110) of the rod (11) axially more to the interior without presenting point J. The convexity of said profile, of radius R, whose center of curvature is located on the line D "of greatest axial width, is such that the thickness e of the heel B, measured in a perpendicular to said meridian profile at a point C of height hc equal to 34 mm, measured with respect to the heel base Y / Y ', equal to 19 mm, or 2.5 times the thickness e of the side measured on line D "of greatest axial width , while the thickness of the heel of figure 1, measured under the same conditions, is equal to 22 mm. The heel is also characterized by the presence of a reinforcement reinforcement (6) composed of a heel reinforcement fabric (61), formed by metallic circumferential elements, of steel, which are 19 x 28 metal cables cut, being the length of said elements or cable sections equal to a quarter of the circumferential length of said fabric (61), measured in its radius of placement prior to the shaping of the unvulcanized blank of the carcass reinforcement, said fabric (61) being placed axially inside the carcass reinforcement (2) and not axially outside the fold (20) of the carcass reinforcement (2). The spaces between ends of elements before shaping the blank have a small amplitude (3 mm) and are circumferentially offset from each other. The radially inferior end of the fabric (61) A magnitude equal to 227 mm is distant from the axis of rotation of the tire, that is to say, comprised between the distance of 223 mm separating the straight line D passing through the point from the axis of rotation of the almost circular covering layer. (110) of the first anchor rod (11), closer to the axis of rotation, and the distance of 233 mm separating the line D 'from the axis of rotation passing through the point of the cover layer (110) more away from the aforementioned axis of rotation.

As regards the radially superior end, this, in the described case, is located radially at a distance r from the axis of rotation equal to 255 mm, which is comprised between a measurement of 265 mm, equal to the semisum 260 mm of the respective ones distances to the axis of rotation of lines D and D "(297 + 232) / 2, with the straight line D" having the greatest axial width passing through point A, at 297 mm from the axis of rotation, increased in the radial half-direction of 5 mm between lines D and D '(233 - 223) / 2, and a measurement of 255 mm, equal to the semisum 260 mm of the respective distances to the axis of rotation of lines D and D "decreased at half-distance 5 mm radial between lines D and D. The heel B, shown in figure 3, has, seen in meridian section, a meridian profile of carcass reinforcement (2), which, as in the case of figure 2 , between the point A of greatest 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, in a continuous manner, convex, with no inflection point J in the region of the bead. The said heel of figure 3 differs from that of figure 2, on the one hand, by the fact that the first rod (11), axially and radially more to the interior, is a "braided" type rod, which, with cross-sectional area equal to the cross-sectional area of a rectangular wire rod, allows an overall smaller volume and, on the other hand, 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 heel and the weight reduction of the tire. The above arrangement allows to obtain a heel thickness e, measured in a perpendicular to said meridian profile at a point C of height hc, equal to 30 mm, measured with respect to the base of the heel YY ', equal to 17 mm, that is to say 2.2 times the thickness e of the side measured on the line D "of greatest axial width The reinforcing fabric (6) of the heel, composed of circumferential elements, is placed, as in the case shown in FIG. 2, axially to the interior of the carcass reinforcement (2) and not axially to the outside of the fold (20) of the carcass reinforcement (2) The heel B of figure 4 differs from that of figure 3 only in the fact that the carcass reinforcement ( 2) of the considered tire, is composed of a first part (21) formed by metal cables, and two parts (22) formed by textile cables.The first part (21) has, on the one hand, a meridian profile tracing that goes under the crown (not shown) and on the sides and, on the other hand, two bo rdes (210) partially bent around the complex formed by the anchor rod (11) and the profile (73). Each second part has an axially inner edge (220), which has a common length of overlap with an edge (210) of the first part, and such that the radially upper end of said edge is radially within the radially upper end of the second part. the additional reinforcing fabric (61). Said second part is folded around the rod (11), to then wind around the single filler (73) and present a second edge located radially below the rod (11). The PAR tires of the measures described and comprising heels with two "braided" type rods, a thinned carcass reinforcement profile, and an additional heel reinforcement fabric, of circumferential elements, and located axially inside the carcass reinforcement, have been compared with: - usual Pt tires, that is, comprising heels of usual thickness, comprising only a rod of rectangular threads and in which the reinforcement fabric of the heel is a continuous metallic wire fabric oriented at 22 ° with respect to the circumferential direction and axially disposed to the outside of the fold of the carcass reinforcement, as shown in figure 1 of the drawings, - PA tires, identical to the Pt tires, but with heels with two anchor rods, and - PB tires, identical to Pt tires, but with tapered edges, a rod of type "braided", and an additional reinforcement of the heel, of. circumferential elements and located axially inside the carcass reinforcement. The comparison has been made under two quality criteria, fundamental for the resistance of the tire beads: resistance with overload, and resistance in hot rim. In the same conditions of taxi for all the tires tested (tested 2 per category), the usual Pt tires, average 36,000 km in running with overload and 5,100 km in roda e in hot rim. The PA tires with heels with two rods, do, respectively, in the same two runs, 27,000 km and 21,000 km, which represents a significant gain in hot tire running. The PB tires have made, under the same conditions of taxi and in the two tests, 72,000 km and 5,900 km, while the PAB tires have made 93,000 km and 31,000 km, which represents considerable progress. Pc tires comprising heels of normal thickness, two anchoring rods in each heel, and an additional reinforcing bead reinforcement, of circumferential elements and located axially inside the carcass reinforcement, have, in turn, reached the kilometers that they follow: 61,000 km in taxi with overload and 29,000 km in taxi with hot rim. The aforementioned results show, in a very clear way, the powerful effect of the presence of two anchor rods in a bead on the behavior in terms of resistance in hot rim running. On the other hand, in a running underload, the aforesaid presence is far from being beneficial, being rather ominous in the case of a tire of normal constitution with normal thicknesses and normal reinforcement reinforcement of the heel. The aforementioned harmful influence is canceled out, unexpectedly, in the case of tires in which the usual reinforcing reinforcement of the heel has been replaced in the fold of the carcass reinforcement, by a reinforcement reinforcement, of circumferential elements and located axially the interior of the carcass reinforcement and, even more unexpectedly, becomes a beneficial effect in the case of tires comprising thinned heels combined with the presence of the additional reinforcement reinforcement, of circumferential elements, inside the the carcass reinforcement, at the same time as it improves, also, the running performance in a hot rim, which makes the PAB combination particularly profitable. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention is the conventional one for the manufacture of the objects or products to which it refers.

Claims (11)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. Tire with H / S aspect ratio less than 0.8 for equipping a vehicle carrying heavy loads, said tire comprising at least one radial carcass reinforcement, formed by at least one fabric of inextensible reinforcing elements, anchored in each bead B, at least, two rods next to each other, folded around the first rod and then wound around the second rod to form a fold, characterized in that, seen in meridian section, an additional reinforcement reinforcement formed by at least one web of circumferential reinforcing elements is positioned along the carcass reinforcement, at least axially to the interior, said reinforcing arm having, on the one hand, its radially lower end radially below the straight D ', parallel to the axis of rotation and passing through the point, of the covering layer of the first anchor rod, radially farthest from the axis of rotation, eg above the line D, parallel to the axis of rotation and passing through the point, of the covering layer of the first anchor rod, radially closer to the axis of rotation and, on the other hand, its radially upper end of the additional reinforcing reinforcement located at a radial distance from line D, comprises between a quantity equal to the radial half-distance between lines D and D "increased in the radial half-distance between lines D and D 'and a magnitude equal to the radial semidistance between lines D and D 'decreased in the radial semidistance between lines D and D', with line D being the one with the greatest axial width.

2. Tire according to claim 1, characterized in that, in the region of the heel B, the tracing of the meridian profile of said reinforcement changes curvature to become rectilinear or concave up to the point of tangency T with the almost circular covering layer of the tire. first anchor rod.

3. Tire in accordance with the claim 1, characterized in that the meridian profile of the carcass reinforcement, seen in meridian section, has a path, comprised between the point A of greatest axial width and the point of tangency T with the coating layer, almost circular, of the first rod Anchor, convex and circular along its entire length, being the center of curvature in the line D "of greater axial width, such that the thickness e of the heel B, measured in a perpendicular to the said meridian profile at a point C of height hc, between 30 and 40 mm, measured with respect to the heel base YY ', is between 2 and 2.5 times the thickness e of the side measured on line D "of greatest axial width.

4. Tire according to any of claims 2 or 3, characterized in that the meridian profile of the carcass reinforcement, tangent T to the coating of the first rod, axially and radially, more to the inside, is then wound around said rod going radially from outside to inside and axially from inside to outside, and then axially extend to the outside to the second rod, to wind around said rod going radially from inside to outside and axially from outside to inside to form a fold that runs radially from the outside. outside to the inside to join the first rod axially inside.

5. A tire according to any of claims 2 or 3, characterized in that the fold end of the carcass reinforcement is located radially below the axial rod and radially further inside.

6. Tire according to any of claims 2 or 3, characterized in that the line joining the two centers of gravity of the cross sections of the rods and forms with the axis of rotation an angle ß, open axially and radially to the outside, included between 20 ° and 60 °.

7. Tire according to any of claims 2 or 3, characterized in that the circumferential reinforcing elements of the reinforcement reinforcement of the bead B are metallic and steel.

8. A tire according to any of claims 2 or 3, characterized in that the anchoring rods and the carcass reinforcement are rods of the "braided" type.

9. Tire according to any of claims 2 to 6, characterized in that the reinforcing elements of the reinforcement reinforcement of the bead B, are sections, or sets of sections, of metallic cables of circumferential length comprised between 0.2 and 0.4 times the circumferential length of the reinforcement reinforcement, measured at its radius of placement prior to the shaping of the unvulcanized blank of the carcass reinforcement.

10. Tire according to any of claims 2 or 3, characterized in that the carcass reinforcement is formed by reinforcing elements of textile material.

11. Tire according to any of claims 2 or 3, characterized in that the carcass reinforcement is formed by three parts: a first part of metallic reinforcement elements, passing, at least, under the crown reinforcement and along the sides of the reinforcement. said tire, and two other parts, formed by textile reinforcement elements, folded and wound around the two anchoring rods of each bead B, each edge of the metal part having, with each axially inner edge of a textile part, a length overlap common, located, at least, in the region where the additional reinforcement of circumferential reinforcement elements is located.