Tyre having an optimised bracing reinforcement arrangement

Abstract

The present invention relates to a tyre (1) comprising a crown (7) that comprises a bracing reinforcement (17) formed by winding a strip over multiple circumferential turns. The winding of the strip forms first (45) and second (46) bracing arrangements comprising a singular axial region (Z1). The singular axial region (Z1) is arranged axially in line with the rib (19C) that has the lowest void ratio, or with one of the ribs having the lowest void ratio, from among ribs (19A, 19B, 19C, 19D, 19E) of the tread (33) of the tyre (1).

Description

[0001] Pneumatics featuring an optimized shrink-fit reinforcement arrangement

[0002] The technological field of the invention is that of tires, particularly for passenger cars and vans.

[0003] The invention relates to a tire comprising a crown, two sidewalls, and two bead ribs, each sidewall connecting each bead to the crown. The crown of the tire comprises a tread and also a crown reinforcement arranged radially internally to the tread and a carcass reinforcement arranged radially internally to the crown reinforcement within the crown and anchored in each bead.

[0004] The top reinforcement comprises a working reinforcement and a shrinkage reinforcement. The working reinforcement is arranged radially internally to the shrinkage reinforcement. The working reinforcement includes at least one working layer. The shrinkage reinforcement comprises a strip wound in several circumferential turns and extends axially within the top reinforcement.

[0005] Document KR101148609B1 discloses a shrink-fitting armature in which the strip is wound in several circumferential turns to form first and second shrink-fitting arrangements radially superimposed on one another, the second shrink-fitting arrangement being arranged radially externally to the first shrink-fitting arrangement. The strip includes a circumferential starting edge and a circumferential ending edge. The shrink-fitting armature of KR101148609B1 includes a first portion of the first shrink-fitting arrangement extending axially from the circumferential starting edge to a first strip reversal zone. The shrink-fitting armature also includes a first portion of the second shrink-fitting arrangement, in contact with the first portion of the first shrink-fitting arrangement, extending axially from the first reversal zone to a strip release zone.The shrink-fit reinforcement then comprises a second portion of the first shrink-fit arrangement, extending axially from the first portion of the second shrink-fit arrangement from the step-off zone to a second strip reversal zone. Finally, the shrink-fit reinforcement comprises a second portion of the second shrink-fit arrangement, in contact with the second portion of the first shrink-fit arrangement, extending axially from the second reversal zone to the circumferential end edge.

[0006] JPH11105152A, W02008 / 035646A1 and EP0313362A2 each disclose a tire having a shrink-fit structure similar to that of KR101148609B1.

[0007] It was noted that the tires disclosed in KR101148609B1, JPH11105152A, W02008 / 035646A1 and EP0313362A2, despite the presence of two shrink-fit arrangements, showed traces of penetration of corrosive agents into the top reinforcement via the shrink-fit reinforcement.

[0008] Thus, the invention aims to define a vertex arrangement that limits the entry of corrosive agents.

[0009] The invention relates first to a tire comprising a crown, two sidewalls, and two bead ribs, each sidewall connecting each bead to the crown. The crown comprises a tread with ribs, and the crown includes a crown reinforcement with a radially arranged shrink-fit reinforcement inside the tread. The shrink-fit reinforcement comprises a strip wound in several circumferential turns to form first and second shrink-fit arrangements and includes a starting circumferential edge and an ending circumferential edge. The second shrink-fit arrangement is arranged radially outside the first shrink-fit arrangement. A first portion of the first shrink-fit arrangement, in contact with a bearing surface, extends axially from the starting circumferential edge to a first strip reversal zone.A first portion of the second shrink-fit arrangement, in contact with the first portion of the first shrink-fit arrangement, extends axially from the first turning zone to a strip release zone. A second portion of the first shrink-fit arrangement, in contact with the bearing surface, extends axially from the first portion of the second shrink-fit arrangement from the release zone to a second strip turning zone. A second portion of the second shrink-fit arrangement, in contact with the second portion of the first shrink-fit arrangement, extends axially from the second turning zone to the circumferential end edge.The shrink-fit reinforcement includes a singular axial zone comprising the circumferential starting and / or ending edge and comprising (i) a portion of the first shrink-fit arrangement in which the first shrink-fit arrangement is not radially overlapped by the second shrink-fit arrangement, and / or (ii) a portion of a third shrink-fit arrangement in which the third shrink-fit arrangement radially overlaps the second shrink-fit arrangement. The singular axial zone is partially arranged axially, among the ribs, with the rib having the lowest notch ratio or with one of the ribs having the lowest notch ratio.

[0010] The invention has as its second object a tire comprising a crown, two sidewalls, two beads, each sidewall connecting each bead to the crown, the crown comprising a tread including ribs, the crown comprising a crown reinforcement including a shrink-fit reinforcement arranged radially inside the tread, the shrink-fit reinforcement comprising a strip A and a strip B wound on several circumferential turns so as to form first and second shrink-fit arrangements, each strip A and strip B comprising a circumferential starting edge and circumferential finishing edge, the second shrink-fit arrangement being arranged radially externally to the first shrink-fit arrangement.A first portion of the first shrink-fit arrangement, in contact with a bearing surface, comprises several circumferential turns of strip A and extends axially from the circumferential starting edge of strip A to a turning zone of strip A. A first portion of the second shrink-fit arrangement, in contact with the first portion of the first shrink-fit arrangement, comprises several circumferential turns of strip A and extends axially from the turning zone of strip A to the circumferential ending edge of strip A. A second portion of the first shrink-fit arrangement, in contact with the bearing surface, comprises several circumferential turns of strip B and extends axially from the circumferential starting edge of strip B to a turning zone of strip B.A second portion of the second shrink-fit arrangement, in contact with the second portion of the first shrink-fit arrangement, comprises several circumferential turns of strip B and extending axially from the turning zone of strip B to the circumferential arrival edge of strip B. The shrink-fit reinforcement comprises a singular axial zone, comprising at least one of the circumferential starting and / or arrival edges of strip A or strip B and comprising (i) a portion of the first shrink-fit arrangement in which the first shrink-fit arrangement is not radially covered by the second shrink-fit arrangement and / or (ii) a portion of a third shrink-fit arrangement in which the third shrink-fit arrangement radially covers the second shrink-fit arrangement.The singular axial zone is partly arranged axially vertically, among the ribs, to the rib with the lowest notching rate or to one of the ribs with the lowest notching rate.

[0011] In practice, each rib is delimited by its two lateral faces and one face of the running surface. The total volume VT of each rib corresponds to the volume that the elastomeric material would occupy between the different faces described above in the theoretical case where each rib had no notches. Thus, we have the following relationship: VT = VE + VC, where VC is the volume of elastomeric material actually contained in each rib, and VE is the volume of notches in each rib. The ratio of the notch volume VE to the total volume VT determines a volumetric notching ratio TEV such that TEV = VE / VT.

[0012] The arrangement of the singular axial zone directly above the rib with the lowest notch ratio, or one of the ribs with the lowest notch ratio, ensures protection of the top reinforcement through the material thickness of the aforementioned rib, while taking into account the volumetric notch ratio of each rib. To this end, the singular axial zone may have an axial portion directly above the aforementioned rib and a complementary portion that is not directly above it. In order to maximize the protection effect of the top reinforcement, the inventors recommend maximizing the axial portion of the singular axial zone located directly above the aforementioned rib.

[0013] The thickness of the aforementioned rib material prevents the entry of corrosive agents into the top reinforcement and also offers increased resistance to perforations.

[0014] The term "in line with a rib" refers to the axial part between the two radial projections of the two lateral faces of that rib.

[0015] In a first variant of the first and second objects of the invention, the singular axial zone comprises the portion of the first shrink-fit arrangement which is not radially covered by the second shrink-fit arrangement and which forms a portion in underthickness.

[0016] In a second variant of the first and second objects of the invention, the singular axial zone comprises the portion of the third shrink-fit arrangement in which the third shrink-fit arrangement radially covers the second shrink-fit arrangement and which forms an overthick portion.

[0017] In a third variant of the first and second objects of the invention, the singular axial zone comprises a portion with less thickness and a portion with more thickness as described above.

[0018] Thus, whatever the object and variant, the singular axial zone has at least one portion with a thickness strictly less than the thickness of the assembly of the first and second arrangements and / or a portion with a thickness strictly greater than the thickness of the assembly of the first and second arrangements.

[0019] In the first variant of each first and second object of the invention, the thickness of the aforementioned rib compensates for the void created by the portion under thickness in order to maintain a sufficient level of protection of the top reinforcement.

[0020] In the second variant of each of the first and second objects of the invention, the thickness of the aforementioned rib allows the thicker portion to be sufficiently distanced from the surface of the tread that is in contact with the ambient air. Thus, the tread thickness prevents perforation and the propagation of potential corrosive agents into the thicker portion.

[0021] The first shrink-fit arrangement has radially internal and external boundaries formed respectively by a radially internal and external surface of the first arrangement. The second shrink-fit arrangement has radially internal and external boundaries formed respectively by a radially internal and external surface of the second arrangement. The thickness of the assembly of the first and second arrangements is the radial distance between the radially internal surface of the first arrangement and the radially external surface of the second arrangement. In the case of a variable thickness, the thickness considered is an average thickness.

[0022] Each first and second object of the invention comprises at least two first and second shrink-fit arrangements forming at least a portion of the shrink-fit reinforcement. Each first and second shrink-fit arrangement is formed from at least one strip wound in several circumferential turns. The first arrangement extends from the circumferential starting edge of the strip in question and externally into contact with a bearing surface of the first arrangement. Preferably, the bearing surface of the first arrangement is formed at least partially by the radially external surface of the working reinforcement. The second arrangement extends to a circumferential ending edge of the strip in question and externally into contact with a bearing surface. Preferably, the bearing surface of the second arrangement is formed at least partially by a radially external surface of the first arrangement.The second shrink-fit arrangement is thus arranged radially externally to the first arrangement and radially internally to the tread.

[0023] The starting circumferential edge of the strip(s) corresponds to one end of the strip, and the ending circumferential edge corresponds to the other end of the strip, the strip being continuous between the first and second ends. Generally, a strip comprises two longitudinal edges extending along the longitudinal direction of the strip and two starting and ending circumferential edges extending along the transverse direction of the strip.

[0024] Each detachment zone is a zone in which the strip changes its bearing surface without changing its axial winding direction, the strip passing from the bearing surface formed by, preferably, the radially outer surface of the first arrangement to the bearing surface of the first arrangement, which preferably is the radially outer surface of the working reinforcement.

[0025] Each reversal zone is a zone in which the strip changes its bearing surface while changing its axial direction of winding, the strip passing from the bearing surface formed by the bearing surface of the first arrangement, which preferably is the radially outer surface of the working reinforcement, to the bearing surface of the second arrangement formed, preferably, by the radially outer surface of the first arrangement.

[0026] A rib is a raised portion of the tread in the radial direction, as opposed to a groove, which is recessed in the radial direction. Because they are delimited by at least one circumferential groove, each rib extends substantially circumferentially. A rib can be circumferentially continuous or circumferentially discontinuous, interrupted by transverse grooves, whether these transverse grooves are blind or open into at least one circumferential groove. We distinguish between so-called central ribs, delimited axially by two adjacent circumferential grooves, and so-called lateral ribs, delimited axially by one circumferential groove and one of the axial edges of the tread surface. Each lateral rib is the outermost axial rib of the tread on each side of the tire's median plane.

[0027] A cut forms a space opening onto the tread surface and is created from a circumferential, axial, or oblique radial groove in the tread. A cut has two main characteristics: a width and a curvilinear length such that the curvilinear length is at least twice the width. A cut is therefore delimited by at least two main lateral faces, connected by a bottom face called the cut bottom, the two main lateral faces being separated by a non-zero distance called the cut width. A cut is such that the main lateral faces cannot come into contact with each other, particularly when the tire is new. A cut oriented in a predominantly circumferential direction is called a "circumferential cut," and a cut oriented in a predominantly axial direction is called a "transverse cut."In cases where the main lateral faces can come into contact with each other, particularly when the tire is new, the cut is a circumferential, radial or oblique notch depending on the main direction of said notch.

[0028] In particular and optional embodiments, the singular axial zone includes a portion devoid of a first shrink-fit arrangement.

[0029] In particular and optional embodiments of the first object of the invention, the step-off zone is arranged axially between the first and second turning zones. In particular and optional embodiments of the second object of the invention, each circumferential arrival edge is arranged axially within its corresponding turning zone.

[0030] In specific and optional embodiments of the first variants, the second shrink-fit arrangement axially covers at least 75%, and preferably at least 90%, of the axial width of the first shrink-fit arrangement. This significantly minimizes the axial width of the singular axial zone, thus facilitating alignment with the aforementioned rib.

[0031] The tire has a roughly toroidal shape around an axis of revolution, which is essentially the same as the tire's axis of rotation. This axis of revolution defines three directions commonly used by those skilled in the art: an axial direction, a circumferential direction, and a radial direction.

[0032] Axial direction refers to the direction parallel to the axis of revolution of the tire, that is, the axis of rotation of the tire.

[0033] Circumferential direction means the direction that is perpendicular to the axial direction and to a radius of the tire.

[0034] Radial direction refers to the direction along a radius of the tire, that is, any direction intersecting the axis of rotation and perpendicular to that axis.

[0035] By meridian plane, we mean a plane containing the axis of rotation of the tire.

[0036] By median plane of the tire (denoted M), we mean the plane perpendicular to the axis of rotation of the tire and which passes through the axial midpoint of the tire.

[0037] The circumferential equatorial plane of the tire refers to the theoretical cylindrical surface passing through the tire's equator, perpendicular to the median plane and the radial direction. The tire's equator, in a meridian plane (a plane perpendicular to the circumferential direction and parallel to the radial and axial directions), is the axis parallel to the tire's axis of rotation and located equidistant between the outermost radial point of the tread intended to be in contact with the ground and the innermost radial point of the tire intended to be in contact with a support, such as a rim.

[0038] Radially inside and radially outside refer to the area closest to and further from the tire's axis of rotation, respectively. Axially inside and axially outside refer to the area closer to and further from the tire's median plane, respectively.

[0039] In preferred embodiments of the invention, the tires are intended for passenger vehicles as defined in the European Tyre and Rim Technical Organisation (ETRTO) standard, 2023. Preferably and optionally, such a tire has a cross-section in a meridional plane characterized by a section height H and a nominal section width or bead size S as defined in the European Tyre and Rim Technical Organisation (ETRTO) standard, 2023, such that the H / S ratio, expressed as a percentage, is at most 90 and at least 20, and the nominal section width S is at least 115 mm and at most 385 mm. Furthermore, the hook diameter D, defining the diameter of the tire's mounting rim, is at least 12 inches and at most 30 inches.

[0040] Any range of values ​​designated by the expression "between a and b" represents the range of values ​​from more than a to less than b (i.e., bounds a and b excluded) while any range of values ​​designated by the expression "from a to b" means the range of values ​​from a to b (i.e., including the strict bounds a and b).

[0041] In advantageous and optional embodiments, the singular axial zone is entirely arranged axially in line with the rib having the lowest notch ratio or with one of the ribs having the lowest notch ratio.

[0042] In other words, the axial width of the aforementioned rib is strictly greater than the axial width of the singular axial zone. Thus, the singular axial zone is optimally protected.

[0043] The width of a rib on a new tire is the maximum distance measured between the two main side faces. If the rib has no chamfer or fillet, the measurement is taken at a radial height coinciding with the tread surface. If the rib has a chamfer or fillet, the measurement is taken at the innermost radial height of the rib and radially inner to the chamfer or fillet. The width is measured approximately perpendicular to the main side faces.

[0044] The width of the singular axial zone is determined as the maximum axial distance of the singular axial zone.

[0045] In advantageous and optional embodiments, the singular axial zone is arranged in an axial portion of the shrink-fitting frame centered on a median plane of the tire and extending axially over an axial width less than or equal to 30%, preferably 20% and more preferably 10% of the axial width of a tread area of ​​the tire.

[0046] Thus, the position of the starting and / or finishing circumferential edge can be common to several tire sizes, particularly for tires with different tread widths. By positioning the starting and / or finishing circumferential edge in the axial portion centered on the median plane, its axial position is no longer dependent on the tire's tread width.

[0047] Conventionally, the tread surface is axially delimited by first and second axial edges, which coincide respectively with the first and second axial edges of the tread. The axial width of the tread surface is the distance measured along the axial direction between the first and second axial edges. The first and second axial edges are determined on a tire mounted on a nominal rim and inflated to the nominal pressure as defined in the ETRTO 2023 standard manual. The first and second axial edges are positioned on either side of the tire's median plane and are formed by lines substantially parallel to the tire's circumferential direction. In the case of a clear boundary between the tread surface and the rest of the tire, the first and second axial edges are determined simply.In the case where the tread surface is continuous with the external surfaces of the sidewalls of the tire, the first and second axial edges are usually determined by loading the tire to 80% of its load capacity according to the ETRTO 2023 standard manual and the first and second axial edges are identified as the axial limits of the tread in contact with the ground.

[0048] In advantageous and optional embodiments, the rib, directly above which the singular axial zone is arranged, is closest axially to the median plane.

[0049] Thus, advantageously, the shrink-fit reinforcement approaches symmetry with respect to the median plane and allows for the design of a particularly uniform tire whose high-speed performance is ensured while offering the desired protection against the penetration of corrosive agents.

[0050] In advantageous and optional embodiments, the portion of the third shrink-fit arrangement extends continuously and circumferentially over at least 75%, preferably at least 90% and more preferably 100% of the circumference of the tire.

[0051] Thus, advantageously, the positioning of the third shrink-fit arrangement arranged in line with the aforementioned rib, in particular as close axially as possible to the median plane, makes it possible to improve the performance of the tire in indentation tests.

[0052] To perform these indentation tests (called "breaking energy tests"), the tire assembly (mounted on a rim) is pressurized and successively rests against a series of standardized indenters (the cylindrical shape of the indenters has a greater height than its diameter, and the end of the side exposed to the tire tread is generally rounded). These tests quantify the energy (in Joules) required to achieve the maximum permissible indentation of the tire assembly as a function of the applied load (in kilograms) and the vertical displacement (in millimeters) of the assembly toward the indenter. Such tests are described in standards such as FMVSS-139, proposed by the NHTSA (National Highway Traffic Safety Administration - USA), where the indenter must be aligned with the protective raised element closest to the centerline.

[0053] In advantageous and optional embodiments, the portion of the third shrink-fit arrangement extends axially over at least 80% of the axial width of the aforementioned rib, particularly as close axially as possible to the median plane. This optimizes the tire's resistance to indentation.

[0054] In advantageous and optional embodiments, the strip, or each strip A and strip B, includes at least one wire reinforcement element for shrinking.

[0055] Optionally, the wire reinforcement element(s) of the swaging are textile.

[0056] A textile yarn reinforcing element is defined as at least one textile monofilament. Such monofilaments are obtained, for example, by melt spinning, solution spinning, or gel spinning. Textile monofilaments are usually classified into two main categories: natural monofilaments and chemical monofilaments. Natural monofilaments include those of plant origin (including cotton), animal origin, and mineral origin. Chemical monofilaments include man-made and synthetic monofilaments. Man-made monofilaments are manufactured from natural raw materials and include, for example, viscose made from wood pulp. Synthetic monofilaments include organic polymer monofilaments (e.g., polyesters and polyamides) as well as inorganic polymer monofilaments (e.g., glass and carbon).For protection against corrosive agents, the textile monofilament(s) used here are preferably chosen from among chemical monofilaments, preferably from among synthetic monofilaments, and most preferably from among organic polymeric monofilaments. Examples include aliphatic polyamides, particularly polyamide 6-6, polyesters, particularly polyethylene terephthalate, and aromatic polyamides, particularly aramid.

[0057] Optionally, each wire reinforcement element is embedded in a polymer matrix, preferably an elastomeric matrix. The compositions used for these matrices are conventional compositions for calendering reinforcements, typically based on natural rubber or other diene elastomer, a reinforcing filler such as carbon black, a vulcanizing system, and standard additives. Adhesion between the wire reinforcement element(s) and the matrix in which they are embedded is ensured, for example, by a standard adhesive composition, such as an RFL (Resorcinol-Formaldehyde-Latex) type adhesive or an equivalent adhesive, for example, as described in W02013017421 or W02017168109.

[0058] In advantageous and optional embodiments, the tire comprises a carcass layer anchored in each bead, the carcass layer extending radially in each sidewall and radially inward to the crown reinforcement in the crown, the carcass layer comprising carcass wire reinforcement elements extending along a principal direction of each carcass wire reinforcement element forming, with the circumferential direction of the tire: - an angle, in absolute value, ranging from 80° to 90° in a portion of the carcass layer extending radially in each sidewall, and

[0059] - an angle strictly less than 80° in a portion of the carcass layer extending axially into the apex.

[0060] In advantageous and optional embodiments, the top reinforcement includes a working reinforcement comprising a single working layer.

[0061] The presence of a single working layer necessitates reinforcement of the tire's mechanical structure, a reinforcement notably provided by the shrink-fit reinforcement, which comprises the first and second shrink-fit arrangements. In addition to its shrink-fit function, the shrink-fit reinforcement absorbs a greater proportion of the tire's circumferential stresses during inflation, rolling, and centrifugal forces, and thus, through its drift stiffness, contributes more effectively to the tire's guidance function.

[0062] The invention and its advantages will be readily understood in light of the following detailed, non-limiting description with reference to Figures 1 to 8, in which:

[0063] - Figure 1 is a cross-sectional view in a meridian cutting plane of a tire according to a first configuration of a first embodiment of the invention, the first embodiment corresponding to the first object described above,

[0064] - Figure 2 is a top view of the tread of the tire in Figure 1, comprising circumferentially continuous ribs,

[0065] - Figure 3 is a view analogous to Figure 2, of a tire according to a variant of the tread embodiment comprising circumferentially discontinuous ribs including transverse cutouts,

[0066] - Figure 4 is a detailed view of zone IV of figure 1, illustrating a step-off zone in the strip,

[0067] - Figure 5 illustrates a schematic top view of the shrink-fit armature as well as a view in a meridian section plane AA' including the axis of rotation of the tire of Figure 1,

[0068] - Figure 6 is a view analogous to Figure 4, of a tire according to a second configuration of the first embodiment, and

[0069] - Figures 7 and 8 are views similar to Figure 4, of tires respectively according to first and second configurations of a second embodiment of the invention, the second embodiment corresponding to the second object described previously.

[0070] In the figures relating to the tire, a coordinate system X, Y, Z is shown, corresponding to the usual circumferential (X), axial (Y), and radial (Z) directions of a tire. Figure 1 shows a tire 1, conforming to the first variant of the first embodiment of the invention. Tire 1 is substantially of revolution about an axis substantially parallel to the axial direction Y. Tire 1 is intended for a passenger vehicle and has a tire size of 245 / 45R18. Tire 1 is intended to be mounted on a mounting support, for example, a rim.

[0071] The tire 1 includes a vertex 7 comprising a tread 33 comprising a tread surface 31 intended to come into contact with a road surface and a vertex reinforcement 13 extending into the vertex 7 in the circumferential direction X. The vertex reinforcement 13 and the tread 33 are arranged in contact with each other. The apex reinforcement 13 is arranged radially inside the tread 33. The tread 33 also has several circumferential cutouts 21. The tread 33 includes two circumferentially continuous lateral ribs 19A, 19E and circumferentially continuous central ribs 19B, 19C, 19D illustrated in Figure 2, each axially delimited by at least one of the circumferential cutouts 21. Each rib 19A, 19B, 19D, 19E includes transverse cutouts 20 while rib 19C is devoid of transverse cutouts.Rib 19C is the rib closest axially to the median plane M and the one with the lowest notch ratio.

[0072] In one embodiment of the tread, and with reference to Figure 3, the tread 33 comprises several circumferentially discontinuous ribs 25A, 25B, 25C, 25D, and includes transverse cutouts 39 creating a circumferential discontinuity in the rib. In this embodiment, ribs 25B and 25C are the ribs closest axially to the median plane M and have the lowest notch ratio.

[0073] The tire 1 comprises two sidewalls 3 extending radially inwards from the apex 7. The tire 10 further comprises two beads 5 radially inwards from the sidewalls 3. Each sidewall 3 connects each bead 5 to the apex 7.

[0074] The top reinforcement 13 comprises a working reinforcement 15 and a shrink-fit reinforcement 17. The shrink-fit reinforcement 17 is arranged radially outside the working reinforcement 15 and radially inside the tread 33. The shrink-fit reinforcement 17 is therefore radially interposed between the working reinforcement 15 and the tread 33.

[0075] The tire 1 includes a carcass reinforcement 10 anchored in each bead 5. In this case, the carcass reinforcement 10 includes at least one carcass layer 11 and here includes a single carcass layer 11 wrapped around two beads 9. The carcass reinforcement 10, here the carcass layer 11, extends radially in each sidewall 3 and axially in the crown 7 radially internally to the crown reinforcement 13 in the crown 7. The crown reinforcement 13 is arranged radially between the tread 33 and the carcass reinforcement 10.The carcass layer 11 comprises wire carcass reinforcement elements extending along a principal direction. Each wire carcass reinforcement element forms an angle, in absolute value, with the circumferential direction X of the tire 1, ranging from 80° to 90° in a portion of the carcass layer extending radially in each sidewall, and an angle strictly less than 80° in a portion of the carcass layer extending axially in the crown. Examples of such carcass layers are described, in particular, in WO2021074511.

[0076] The working reinforcement 15 includes at least one working layer 16. Here, the working reinforcement 15 includes a single working layer 16. Such working reinforcements are described in particular in WO2021074511.

[0077] The shrink-fitting frame 17 comprises a first shrink-fitting arrangement 45 in contact with the working frame 15 and a second shrink-fitting arrangement 46 in contact with the first shrink-fitting arrangement 45. The second shrink-fitting arrangement 46 is arranged radially externally to the first shrink-fitting arrangement 45.

[0078] The first shrink-fit arrangement 45 is arranged in contact with a bearing surface of the first shrink-fit arrangement 45 formed at least in part by a radially external surface 27 of the working frame 15 forming the bearing surface of the shrink-fit frame 17.

[0079] The second shrink-fit arrangement 46 is arranged in contact with a bearing surface of the second shrink-fit arrangement 46 formed at least in part by a radially external surface 28 of the first arrangement 45.

[0080] With reference to Figures 1, 4 and 5, in the first embodiment, the shrink-fitting frame 17 comprises a single continuous strip 41 wound over several circumferential turns so as to form the first and second shrink-fitting arrangements 45, 46. The second shrink-fitting arrangement 46 axially covers at least 75%, preferably at least 90% of the axial width of the first shrink-fitting arrangement 45.

[0081] The strip 41 comprises, a circumferential starting edge 43 and a circumferential ending edge 44, positioned in the vicinity of the median plane M as well as two longitudinal edges 54, 55.

[0082] The strip 41 here comprises eight to ten wire reinforcement elements embedded in an elastomeric matrix to form a strip with a width ranging from 5.0 mm to 15.0 mm and a thickness ranging from 0.5 mm to 1.0 mm. Each wire reinforcement element comprises two multifilament strands of aromatic polyamide and one strand of polyester, for example as described in WO2021074511.

[0083] The first shrink-fit arrangement 45 comprises a first portion 47 of the first shrink-fit arrangement 45 and a second portion 49 of the first shrink-fit arrangement 45. The second shrink-fit arrangement 46 comprises a first portion 51 of the second shrink-fit arrangement 46 and a second portion 53 of the second shrink-fit arrangement 46.

[0084] For the sake of clarity in Figures 5 to 8, vertical hatching represents the second arrangement, while oblique hatching represents the first arrangement. For example, each reversal zone includes an uncovered portion of the first shrink-fit arrangement, which is therefore represented by oblique hatching. Finally, the bearing surface 27, formed by the radially outer surface of the single working layer 16, is shown without hatching.

[0085] The first portion 47 of the first shrink-fit arrangement 45 is in contact with the bearing surface 27 and extends axially from the circumferential starting edge 43 to a first reversal zone 59A of the strip 41. The first reversal zone 59A corresponds to a first change in the axial winding direction of the strip 41.

[0086] The first portion 51 of the second shrink-fit arrangement 46 is in contact with the first portion 47 of the first shrink-fit arrangement 45 and extends axially from the first reversal zone 59A to a step-off zone 57 of the strip 41.

[0087] The second portion 49 of the first shrink-fit arrangement 45 is in contact with the bearing surface 27 and extends axially the first portion 51 of the second shrink-fit arrangement 46 from a step-off zone 57 of the strip 41 to a second reversal zone 59B of the strip 41. The second reversal zone 59B corresponds to a second change in the axial winding direction of the strip 41.

[0088] The second portion 53 of the second shrink-fit arrangement 46 is in contact with the second portion 49 of the first shrink-fit arrangement 45 and extends axially from the second turning zone 59B to the circumferential arrival edge 44.

[0089] The detachment zone 57 is arranged axially between the first and second reversal zones 59A, 59B.

[0090] As illustrated in Figure 5, the shrink-fit armature 17 includes a singular axial zone Z1 comprising the circumferential starting edge 43 and the circumferential ending edge 44. In the first configuration of the first embodiment, the singular axial zone Z1 includes a portion 65 of the first shrink-fit arrangement 45 in which the first shrink-fit arrangement 45 is not radially covered by the second shrink-fit arrangement 46.

[0091] The portion 65 is said to be under-thick. Indeed, as can be seen in figure 5, the portion 65 has a thickness strictly less than the thickness of the assembly of the first and second arrangements 45, 46. The singular axial zone Z1 is arranged in an axial portion centered on a median plane M of the tire and extends axially over an axial width less than or equal to 30%, preferably 20% and more preferably 10% of the axial width of the tread surface 31 of the tire 1.

[0092] With reference to Figures 1 and 2, the singular axial zone Z1 is at least partially, here entirely, arranged axially above rib 19C. With reference to Figure

[0093] 5, the portion 65 of the first shrink-fit arrangement 45 includes a portion 65A arranged circumferentially between the starting and ending edges 43, 44 and portions 65B extending from the step-off zone 58 to each longitudinal edge 54, 55 of the strip 41.

[0094] We will now describe a second configuration of the first embodiment with reference to Figure 6, by contrasting it with the pneumatic version according to the first variant of the first embodiment. Elements analogous to those described previously are designated by identical reference numerals.

[0095] In the second configuration of the first embodiment, the shrink-fitting frame 17 includes a third shrink-fitting arrangement 48 arranged radially externally to the second shrink-fitting arrangement 46. The singular axial zone Z1 includes a portion 67 of the third shrink-fitting arrangement 48.

[0096] Portion 67 is said to be thicker. Indeed, as can be seen in the figure

[0097] 6, portion 67 has a thickness strictly greater than the thickness of the assembly of the first and second arrangements 45, 46.

[0098] In addition, the singular axial zone Z1 includes a portion 65 of the first shrink-fit arrangement 45 not radially covered by the second shrink-fit arrangement 46 extending here from the step-off zone 57 to each end zone 54 of the strip 41.

[0099] Just as in the first configuration, the singular axial zone Z1 is at least partly, here entirely, arranged axially in line with rib 19C.

[0100] We will now describe a first configuration of the second embodiment with reference to Figure 7, by contrasting it with the configurations described previously. Elements analogous to those described previously are designated by identical reference numerals.

[0101] The shrink-fit armature 17 of the first configuration of the second embodiment comprises a separate strip A and a strip B, i.e., not continuous with each other. Each strip A and strip B is continuous and wound on several circumferential turns so as to form the first and second arrangements 45, 46. Each strip A and strip B comprises respectively a circumferential starting edge 43A, 43B and a circumferential ending edge 44A, 44B positioned here in the vicinity of the median plane M.

[0102] The first portion 47 of the first shrink-fit arrangement 45, in contact with the bearing surface 27, comprises several circumferential turns of the strip A and extends axially from the starting circumferential edge 43A to a turning zone 59A of the strip A. The first portion 51 of the second shrink-fit arrangement 46 comprises several circumferential turns of the strip A and extends axially from the turning zone 59A to the ending circumferential edge 44A.

[0103] The second portion 49 of the first shrink-fit arrangement 45, in contact with the bearing surface 27, comprises several circumferential turns of the strip B and extends axially from the starting circumferential edge 43B to a turning zone 59B of the strip B. The second portion 53 of the second shrink-fit arrangement 46 comprises several circumferential turns of the strip B and extends axially from the turning zone 59B to the ending circumferential edge 44B.

[0104] Each circumferential arrival edge 44A, 44B is arranged axially inside each corresponding turning zone 59A, 59B.

[0105] The shrink-fit reinforcement 17 includes a singular axial zone Z1 comprising a portion 65 of the first shrink-fit arrangement 45 in which the first shrink-fit arrangement 45 is not radially covered by the second shrink-fit arrangement 46. In this case, the portion 65 of the first shrink-fit arrangement 45 comprises four portions 65C, 65D, 65E, and 65F extending between the step-out zone 57A and the longitudinal edge 54A, and between the step-out zone 57B and the longitudinal edge 55B. The singular axial zone Z1 also includes a portion 66 lacking the first shrink-fit arrangement 45.

[0106] Just as in previous configurations, the singular axial zone Z1 is at least partly, if not entirely, arranged axially in line with rib 19C.

[0107] We will now describe a second configuration of the second embodiment with reference to Figure 8, by contrasting it with the configurations previously described. Elements analogous to those described previously are designated by identical reference numerals.

[0108] The shrink-fitting frame 17 includes a third shrink-fitting arrangement 48 arranged radially externally to the second shrink-fitting arrangement 46. The singular axial zone Z1 includes a portion 67 of the third shrink-fitting arrangement 48 in which the third shrink-fitting arrangement 48 radially overlaps the second shrink-fitting arrangement 46. The portion 67 is arranged circumferentially between the circumferential starting edge 43A of the strip A and the circumferential ending edge 44B of the strip B. The portion 67 of the third shrink-fitting arrangement 48 is formed here by a portion of the strip B which partially overlaps the first portion 47 of the first shrink-fitting arrangement 45 and partially overlaps the first portion 51 of the second shrink-fitting arrangement 46.

[0109] The singular axial zone Z1 also includes a portion 65H, 65I of the first shrink-fit arrangement 45 in which the first shrink-fit arrangement 45 is not covered by the second shrink-fit arrangement 46.

[0110] Just as in previous configurations, the singular axial zone Z1 is at least partly, if not entirely, arranged axially in line with rib 19C.

[0111] The invention is not limited to the configurations and embodiments previously described.

[0112] In particular, the structure constituting the strip is not limited to that described previously. Other wire reinforcement elements for the shrink-wrapping could be considered, in addition to those described. A strip made from cut wire reinforcement elements could also be considered.

[0113] We can also consider sculptures more complex than those described previously, including circumferential cutouts with varying general directions.

[0114] It is also possible to consider embodiments in which the working reinforcement comprises two working layers. Such working reinforcements, as well as the associated frame reinforcements, are described in particular in WO2021250331.

[0115] Unlike the configurations and embodiments described above in which the winding pitch of the strip is substantially equal to the width of the strip, embodiments may be considered in which the winding pitch of the strip is strictly greater or strictly less than the width of the strip, and this over all or part of the top.

[0116] We may also consider embodiments in which, contrary to the second configuration of the first embodiment illustrated in Figure 6 in which the portion 67 of the third shrink-fit arrangement 48 is relatively reduced, the portion 67 of the third shrink-fit arrangement 48 extends continuously and circumferentially over at least 75%, preferably at least 90% and more preferably 100% of the circumference of the tire.

[0117] The tires described above can be obtained by a known tire manufacturing process. This process includes a step of forming an intermediate blank lacking the reinforcement and tread. This forming step is carried out on a molding jig. The process also includes a helical winding step of the tread. In one variant, the helical winding step is performed directly on the intermediate blank.

[0118] In a second variant, the helical winding step of the strip is performed on a winding support separate from the forming support and separate from the blank. The winding support includes a strip anchoring device for anchoring the strip at an anchor point located axially near the mid-plane of the winding support. Such an anchoring device is described, for example, in document FR3083475. The process then includes a step of transferring the helical winding of the strip to the intermediate blank by means of a transfer device. Such a transfer device is described, for example, in document EP3554817.

[0119] Thanks to the positioning of the starting edge of each strip near the mid-plane, the only parameters that need to be modified to determine the axial width of the shrink-fit reinforcement are the positions of the turning zones, or in other words, the number of turns required to reach the turning zones. Thus, when two tires have shrink-fit reinforcements with different axial widths, for example, because the tires have different cross-sectional widths, it is possible to use the same process and devices described previously for both tires by changing only the parameters indicated above.

[0120] In the first variant, a person skilled in the art will be able to take a relevant reference point on the intermediate blank and / or the assembly of the winding device relative to the winding device to position the starting edge of the strip. In the second variant, a person skilled in the art will be able to take a relevant reference point on the winding device and / or the winding support and / or the wound shrink-wrap assembly relative to the intermediate blank and / or the assembly of the winding device to position the starting edge of the strip.

Claims

Demands 1. Tire (1) comprising a crown (7), two sidewalls (3), two bead ribs (5), each sidewall (3) connecting each bead rib (5) to the crown (7), the crown (7) comprising a tread (33) comprising ribs (19A, 19B, 19C, 19D, 19E), the crown (7) comprising a crown reinforcement (13) comprising a shrink-fit reinforcement (17) arranged radially inside the tread (33), the shrink-fit reinforcement (17) comprising a strip (41) wound in several circumferential turns so as to form first (45) and second (46) shrink-fit arrangements and comprising a circumferential starting edge (43) and a circumferential finishing edge (44), the second shrink-fit arrangement (46) being arranged radially outside the first shrink-fit arrangement (45),in which a first portion (47) of the first shrink-fit arrangement (45) extends axially from the circumferential starting edge (43) to a first turning zone (59A) of the strip (41), in which a first portion (51) of the second shrink-fit arrangement (46), in contact with the first portion (47) of the first shrink-fit arrangement (45), extends axially from the first turning zone (59A) to a step-off zone (57) of the strip (41), in which a second portion (49) of the first shrink-fit arrangement (45) axially extends the first portion (51) of the second shrink-fit arrangement (46) from the step-off zone (57) to a second turning zone (59B) of the strip (41), in which a second portion (53) of the second shrink-fit arrangement (46), in contact with the second portion of the first shrink-fitting arrangement (49),extends axially from the second turning zone (59B) to the circumferential arrival edge (44), wherein the shrink-fit armature (17) comprises a singular axial zone (Z1) comprising the circumferential starting edge (43) and / or arrival edge (44) and comprising:, - a portion (65) of the first shrink-fit arrangement (45) in which the first shrink-fit arrangement (45) is not radially covered by the second shrink-fit arrangement (46), and / or - a portion (67) of a third shrink-fit arrangement (48) in which the third shrink-fit arrangement (48) radially overlaps the second shrink-fit arrangement (46), and in which the singular axial zone (Z1) is partly arranged axially vertically, among the ribs (19A, 19B, 19C, 19D, 19E), of the rib (19C) having the lowest notch rate or of one of the ribs having the lowest notch rate.

2. Tire (1) comprising a crown (7), two sidewalls (3), two bead ribs (5), each sidewall (3) connecting each bead rib (5) to the crown (7), the crown (7) comprising a tread (33) comprising ribs (19A, 19B, 19C, 19D, 19E), the crown (7) comprising a crown reinforcement (13) comprising a shrink-fit reinforcement (17) arranged radially inside the tread (33), the shrink-fit reinforcement (17) comprising a strip A and a strip B wound in several circumferential turns so as to form first (45) and second (46) shrink-fit arrangements, each strip A and strip B comprising a circumferential starting edge (43A, 43B) and circumferential finishing edge (44A, 44B), the second shrink-fit arrangement (46) being arranged radially externally to the first shrink-fit arrangement (45),wherein a first portion (47) of the first shrink-fit arrangement (45) comprises several circumferential turns of the strip A and extends axially from the starting circumferential edge (43A) of the strip A to a turning zone (59A) of the strip A, wherein a first portion (51) of the second shrink-fit arrangement (46), in contact with the first portion (47) of the first shrink-fit arrangement (45), comprises several circumferential turns of the strip A and extends axially from the turning zone (59A) of the strip A to the ending circumferential edge (44A) of the strip A, wherein a second portion (49) of the first shrink-fit arrangement (45) comprises several circumferential turns of the strip B, and extends axially from the starting circumferential edge (43B) of the strip B to a zone of reversal (59B) of strip B,in which a second portion (53) of the second shrink-fit arrangement (46), in contact with the second portion (49) of the first shrink-fit arrangement (45), comprises several circumferential turns of the strip B and extends axially from the turning zone (59B) of the strip B to the circumferential arrival edge (44B) of the strip B, in which the shrink-fit reinforcement (17) comprises a singular axial zone (Z1), comprising at least one of the circumferential starting edges (43A, 43B) and / or arrival edges (44A, 44B) of the strip A or the strip B and comprising:, - a portion (65A, 65B) of the first shrink-fit arrangement (45) in which the first shrink-fit arrangement (45) is not radially covered by the second shrink-fit arrangement (46) and / or - a portion (67) of a third shrink-fit arrangement (48) in which the third shrink-fit arrangement (48) radially covers the second shrink-fit arrangement (46), and in which the singular axial zone (Z1) is partly arranged axially vertically, among the ribs (19A, 19B, 19C, 19D, 19E), of the rib (19C) having the lowest notch ratio or of one of the ribs having the lowest notch ratio.

3. Pneumatic (1) according to any one of the preceding claims, wherein the singular axial zone (Z1) is fully arranged axially in line with the rib (19C) having the lowest notch ratio or one of the ribs having the lowest notch ratio.

4. Tire (1) according to any one of the preceding claims, wherein the singular axial zone (Z1) is arranged in an axial portion of the shrink-fitting frame centered on a median plane (M) of the tire and extending axially over an axial width less than or equal to 30% of the axial width of a tread surface (31) of the tire (1).

5. Tire (1) according to claim 4, wherein said axial portion of the shrink-fitting frame extends axially over an axial width less than or equal to 20%, preferably 10%, of the axial width of the tread surface (31) of the tire (1).

6. Pneumatic (1) according to any one of the preceding claims, wherein the rib (19C), above which the singular axial zone (Z1) is arranged, is closest axially to the median plane (M).

7. Tire (1) according to any one of the preceding claims, wherein the portion (67) of the third shrink-fit arrangement (48) extends continuously and circumferentially over at least 75%, preferably at least 90% and more preferably 100% of the circumference of the tire.

8. Pneumatic (1) according to any one of the preceding claims, wherein the strip (41) or each strip A and strip B comprises at least one wire reinforcement element for shrinking.

9. Tire (1) according to any one of the preceding claims, comprising a carcass layer (11) anchored in each bead, the carcass layer extending radially in each sidewall and radially inwardly to the crown reinforcement in the crown, the carcass layer (11) comprising carcass wire reinforcement elements extending along a principal direction of each carcass wire reinforcement element forming, with the circumferential direction of the tire: - an angle, in absolute value, ranging from 80° to 90° in a portion of the carcass layer extending radially in each flank, and - an angle strictly less than 80° in a portion of the carcass layer extending axially into the apex.

10. Pneumatic (1) according to any one of the preceding claims, wherein the top reinforcement comprises a working reinforcement (15) comprising a single working layer.

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