Method for Simplifying the Manufacture of a Tire Having a Single Actuating Layer

Abstract

The present invention relates to a method for manufacturing a tire comprising a carcass ply and a single working layer in which the working fibrous reinforcing elements (180) form an angle AT in the range of 27° to 40° with the circumferential direction of the tire, during which a carcass assembly intended to form the carcass ply is formed by winding the carcass ply, the carcass fibrous reinforcing elements (340) forming an initial angle A3 in the range of 80° to 90° in absolute value with the circumferential direction (x) of the support.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a tire and a tire manufactured by such a method.

Background Art

[0002] A tire comprising a crown, two sidewalls, and two beads, with each sidewall connecting each bead to the crown, is known from the prior art, in particular from EP3489035. Each bead generally comprises at least one circumferential reinforcing element in the form of a bead wire.

[0003] The tire also comprises a carcass reinforcement fixed within each bead and extending within each sidewall and within the crown. The carcass reinforcement comprises a single carcass layer wound around each circumferential reinforcing element.

[0004] The crown comprises a tread intended to come into contact with the road surface when the tire is in motion, and a crown reinforcement arranged radially between the tread and the carcass reinforcement. The crown reinforcement comprises an actuation reinforcement having a single actuation layer. The crown reinforcement also comprises a hoop reinforcement arranged radially outside the actuation reinforcement.

[0005] As described above, a particular feature of the tire described in EP3489035 is the elimination of one actuation layer compared to a conventional tire having two actuation layers in the actuation reinforcement. In EP3489035, the advantage of eliminating one of the actuation layers is that it reduces the amount of material and thus the mass of the tire while improving its circumferential stiffness, which, on the other hand, results in a decrease in shear stiffness, and this decrease is still acceptable considering the material savings.

[0006] The method for manufacturing a tire in EP3489035 comprises a step in which a carcass assembly intended to form a carcass layer is formed by winding a carcass ply around a support, as is known in particular from FR2797213 and from FR1413102 in the prior art. The carcass assembly comprises carcass fibrous reinforcing elements extending along a main direction forming an initial angle with the circumferential direction of the support, which initial angle depends on the angle intended to be obtained in the tire following the manufacturing method.

[0007] Next, an actuating assembly intended to form an actuating layer is formed by winding an actuating ply radially outside the carcass assembly. The actuating assembly also comprises actuating fibrous reinforcing elements extending along a main direction forming an initial angle with the circumferential direction of the support, which initial angle depends on the angle intended to be obtained in the tire following the manufacturing method. The carcass assembly and the actuating assembly then form an assembly having a substantially cylindrical shape.

[0008] Next, the assembly having a substantially cylindrical shape is deformed in order to obtain an assembly having a substantially annular shape, for which purpose - the main direction of each carcass fibrous reinforcing element forms a final angle equal to 70° with respect to the deformation S1 in EP3489035 and equal to 43° with respect to the deformation S2 in the axial central part of the carcass assembly extending axially radially aligned with the actuating assembly, and forms with the circumferential direction of the support, and - the main direction of each actuating fibrous reinforcing element forms a final angle equal to -40° with respect to the deformation S1 in EP3489035 and equal to -24° with respect to the deformation S2 with the circumferential direction of the support.

[0009] Next, the green form of the tire obtained from the assembly having a substantially annular shape is crosslinked in order to obtain the tire. In this tire, the main direction of each carcass fibrous reinforcing element forms an angle equal to the final angle obtained following the deformation step with the circumferential direction of the tire. The main direction of each actuating fibrous reinforcing element forms an angle equal to the final angle obtained following the deformation step with the circumferential direction of the tire.

[0010] Before the step of forming the carcass assembly by winding the carcass ply, the carcass ply is manufactured by arranging carcass fibrous reinforcing elements parallel to each other and embedding them in an uncrosslinked composition comprising at least an elastomer, for example by a skim coating, the composition being intended to form an elastomer matrix in a crosslinked state. A ply known as a straight ply is obtained in which the carcass fibrous reinforcing elements are parallel to each other and parallel to the main direction of the carcass ply. Next, each part of the carcass ply is cut at a cutting angle, and these parts are abutted so that the main direction along which the carcass fibrous reinforcing elements extend parallel to each other forms an angle equal to the cutting angle with the main direction of the carcass ply, and a ply known as an inclined ply having an angle equal to the above-mentioned initial angle is obtained. The working ply is manufactured in a similar manner.

[0011] In order to obtain the same final angle within tires of different sizes, it is necessary to use different initial angles taking into account the degree of shaping that varies between different sizes, which theoretically requires manufacturing as many carcass plies and working plies as there are tire sizes. However, managing such a large number of plies in a factory is complex and expensive.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0013] The object of the present invention is to enable the simplified manufacture of a tire having a limited number of carcass plies and a single working layer from the working plies while maintaining its shear stiffness and its circumferential stiffness, which are the main mechanical characteristics of the tire.

Means for Solving the Problems

[0014] To this end, the subject of the present invention is a method for manufacturing a tire comprising a crown, two sidewalls, and two beads, each sidewall connecting each bead to the crown, the tire comprising a carcass reinforcement fixed in each bead and extending radially inward of the crown within each sidewall, the carcass reinforcement comprising at least one carcass layer, the crown comprising - a tread intended to come into contact with the road surface when the tire is running, - a crown reinforcement arranged radially between the tread and the carcass reinforcement, the crown reinforcement comprising a working reinforcement having a single working layer, the working layer being axially delimited by two axial edges of the working layer and comprising working fibrous reinforcing elements, the working fibrous reinforcing elements extending axially from one axial edge of the working layer to the other axial edge of the working layer substantially parallel to each other along the main direction of each working fibrous reinforcing element forming an angle AT with the circumferential direction of the tire, the crown reinforcement as described above and comprising In this method, - a carcass assembly intended to form at least one carcass layer is arranged around a support having a substantially cylindrical shape around a main axis, the carcass assembly being axially delimited by two axial edges of the carcass assembly and comprising carcass fibrous reinforcing elements extending axially substantially parallel to each other from one axial edge of the carcass assembly to the other axial edge of the carcass assembly, each carcass fibrous reinforcing element extending within the carcass assembly along the main direction of each carcass fibrous reinforcing element forming an initial angle A3 with the circumferential direction of the support - The actuating assembly intended to form the actuating layer is arranged radially outside the carcass assembly, and the carcass assembly and the actuating assembly form an assembly having a substantially cylindrical shape around the main axis of the support. - The assembly having a substantially cylindrical shape around the main axis of the support is deformed to obtain an assembly having a substantially annular shape around the main axis of the support. - The green form of the tire obtained from the assembly having a substantially annular shape is crosslinked to obtain the tire. In this method, the angle A3 is in the range of 80° to 90° in absolute value, and the angle AT is in the range of 27° to 40° in absolute value.

[0015] By using an initial angle A3 in the range of 80° to 90° in absolute value, it is sufficient for each ply to have one or more carcass plies with a single cut angle between 80° and 90° in this case for arranging the carcass assembly. That is, it is possible to avoid the need to manufacture the same number of carcass plies as there is a tire size. The angle range of 80° to 90° makes it possible in particular to take into account the industrial variability of the manufacturing method during the skim coating stage, which results in a straight ply where the initial angle A3 can vary by up to 10° with respect to the theoretical value of 90°. Implicitly, the initial angle A3 is constant when moving axially from one axial edge of the carcass assembly to the other axial edge.

[0016] Inside the tire, the angle of the main direction of each carcass fibrous reinforcing element at the axial center part of the carcass layer thus depends on the degree of shaping and the initial angle of the main direction of each actuating fibrous reinforcing element. Its shear stiffness and its circumferential stiffness, which are the main mechanical properties of the tire, can thus be obtained by simply varying the initial angle of the main direction of each actuating fibrous reinforcing element according to the degree of shaping. The method according to the invention thus makes it possible that only the different actuating plies need to be managed.

[0017] As shown by the following test results, satisfactory shear stiffness and circumferential stiffness can be obtained within an angular range AT of 27° to 40°. Even if a slight decrease in these stiffnesses is observed, particularly with respect to the circumferential stiffness, this decrease is largely compensated for by the simplification of the method and the reduction in the number of carcass plies that are managed.

[0018] According to the present invention, the actuating reinforcement comprises a single actuating layer. The presence of a single actuating layer makes it possible in particular to lighten the tire, and thus to reduce the energy dissipated by the crown hysteresis, and thus to reduce the rolling resistance of the tire. That is, the actuating reinforcement does not have, other than the actuating layer, a layer reinforced by fibrous reinforcement elements. Such fibrous reinforcement elements of the reinforcement layer excluded from the actuating reinforcement of the tire comprise metallic fibrous reinforcement elements and fabric fibrous reinforcement elements. Very preferably, the actuating reinforcement is composed of a single actuating layer.

[0019] The carcass assembly may be intended to form a single carcass layer, or may be intended to form two carcass layers, for example by winding this carcass assembly over two turns. Thus, in an embodiment in which the tire comprises two carcass layers, for example, a single carcass assembly can be arranged by winding it over two turns, or a first radially inner carcass assembly can be arranged and a second radially outer carcass assembly arranged around the first radially inner carcass assembly, where each first and second carcass assembly may be intended to form each carcass layer.

[0020] Within the scope of the present invention, the actuating assembly is intended to form a single actuating layer.

[0021] In a preferred manner that enables the use of a relatively simple method, the carcass assembly is formed by winding a carcass ply or several carcass plies around a support, and the actuating assembly is formed by winding an actuating ply or a plurality of actuating plies radially outside the carcass assembly.

[0022] In a simplified method where only one carcass ply is handled to form each carcass assembly and circumferential joints are avoided between several carcass plies having an axial width smaller than the axial width of each carcass assembly to be formed, each carcass assembly is composed of one carcass ply intended to form each carcass layer. In other words, each carcass ply is axially continuous.

[0023] When each carcass assembly is formed by a plurality of carcass plies, it is preferable to use a plurality of carcass plies in which the main directions of the carcass fibrous reinforcing elements are all parallel to each other.

[0024] Similarly, in a simplified method where only one actuating ply is handled to form the actuating assembly and circumferential joints are avoided between a plurality of actuating plies having an axial width smaller than the axial width of the actuating assembly to be formed, the actuating ply is obtained from an actuating ply intended to form a single actuating layer. In other words, each actuating ply is axially continuous.

[0025] When the actuating assembly is formed by a plurality of actuating plies, it is preferable to use a plurality of actuating plies in which the main directions of the actuating fibrous reinforcing elements are all parallel to each other. Of course, it is possible to assume main directions of actuating fiber reinforcing elements that are not parallel to each other for each actuating ply.

[0026] The tire of the present invention is preferably intended for passenger cars defined in accordance with the European Tyre and Rim Technical Organization or "ETRTO" standard (2019) of 2019. Such a tire has a cross-section in a meridional plane of the cross-section characterized by a cross-section height H and a nominal cross-section width S in accordance with the European Tyre and Rim Technical Organization or "ETRTO" standard (2019), in which case the ratio H / S expressed as a percentage is equal to at most 90, preferably equal to at most 80, more preferably equal to at most 70, at least equal to 30, preferably at least equal to 40, the nominal cross-section width S is at least equal to 115 mm, preferably at least equal to 155 mm, more preferably at least equal to 175 mm, equal to at most 285 mm, preferably equal to at most 315 mm, more preferably equal to at most 285 mm, more preferably equal to at most 55 mm. In addition to this, the diameter D at the rim flange defining the diameter of the mounting rim of the tire is at least equal to 12 inches, preferably at least equal to 16 inches, equal to at most 24 inches, preferably equal to at most 20 inches.

[0027] The axial direction is understood to be the direction substantially parallel to the main axis of the tire or support, i.e., the axis of rotation of the tire or support.

[0028] The circumferential direction is understood to be the direction substantially perpendicular to the axial direction or to the radius of the tire or support (in other words, tangent to the circle centered on the axis of rotation of the tire or support).

[0029] The radial direction is understood to be the direction along the radius of the tire or support, i.e., any direction intersecting the axis of rotation of the tire or support and substantially perpendicular to that axis.

[0030] The median plane of the tire (denoted as M) is understood to be the plane perpendicular to the axis of rotation of the tire located in the middle between the two beads and passing through the axial center of the crown reinforcement.

[0031] The median plane of the assembly (denoted as m) is understood to be a plane perpendicular to the axis of rotation of the support located axially midway between the axial edges of the assembly in each axial direction.

[0032] The equatorial circumferential surface of the tire (denoted as E) is understood to be a theoretical cylindrical surface passing through the equator of the tire perpendicular to the median plane and the radial direction. The equator of the tire is parallel to the axis of rotation of the tire in the meridian plane (a plane perpendicular to the circumferential direction and parallel to the radial and axial directions), and is an axis located equidistantly between the radially outermost point of the tread intended to contact the road surface and the radially innermost point of the tire intended to contact the support, for example, a rim, and the distance between these two points is equal to H.

[0033] The equatorial circumferential surface of the assembly (denoted as e) is understood to be a theoretical cylindrical surface passing through the equator of the assembly perpendicular to the median plane and the radial direction. The equator of the assembly is parallel to the axis of rotation of the support in the meridian plane (a plane perpendicular to the circumferential direction and parallel to the radial and axial directions), and is an axis located equidistantly between the radially outermost point and the radially innermost point of the assembly, and the distance between these two points is equal to h.

[0034] The meridian plane is understood to be a plane parallel to and including the axis of rotation of the tire and perpendicular to the circumferential direction.

[0035] The bead is understood to be the part of the tire intended to be able to attach the tire to a mounting support, for example, a wheel having a rim. Thus, each bead is intended to contact, in particular, the flange of the rim enabling attachment to the rim.

[0036] The main direction in which the fibrous reinforcing element extends is understood to be the direction in which the fibrous reinforcing element extends along its maximum length. The main direction in which the fibrous reinforcing element extends can be linear or curved, and the reinforcing element can exhibit a linear or wavy path along its main direction.

[0037] The portion of the assembly, layer, or tire located between the axial edges of the assembly, layer, or reinforcement is understood to be the portion that extends axially and is located between the radial planes passing through the axial edges of the assembly, layer, or reinforcement.

[0038] A portion of the assembly intended to extend axially, a portion of the assembly that extends axially, or a portion of a layer that extends axially radially aligned with a reference assembly or reference layer is understood to be the portion of the assembly or layer located between the radial projections of the axial edges of the reference assembly or reference layer of the assembly or layer.

[0039] The range of values indicated by the expression "between a and b" represents a range of values extending from greater than a to less than b (i.e., excluding the endpoints a and b), whereas the range of values indicated by the expression "from a to b" means a range of values extending from the endpoint "a" to the endpoint "b" (i.e., including the exact endpoints "a" and "b").

[0040] Within the tire, the angle in question is the smaller of the two angles defined between a reference line (in this case, the circumferential direction of the tire) and the main direction in which the fibrous reinforcing element in question extends, in absolute value.

[0041] Within the tire and during the method, the orientation of the angle is understood to be in the clockwise or counterclockwise direction, and it is necessary to change the orientation from the reference line (in this case, the circumferential direction of the support or tire) by which the angle is defined to reach the main direction in which the fibrous reinforcing element in question extends.

[0042] In this method, the problem angle formed by the main direction in which the actuating fibrous reinforcing element and the carcass fibrous reinforcing element extend is, by definition, an angle having an opposite direction, and the angle formed by the main direction in which each actuating fibrous reinforcing element extends is the smaller of the absolute values of two angles defined between a reference line (in this case, the circumferential direction of the support or the circumferential direction of the tire) and the main direction in which the actuating fibrous reinforcing element extends. Accordingly, the angle formed by the main direction in which each actuating fibrous reinforcing element extends defines an opposite direction to the angle formed by the main direction in which each carcass fibrous reinforcing element extends.

[0043] In embodiments where there are minor industrial variations during the manufacture of the carcass ply, the angle A3 is in the range of 85° to 90° in absolute value, preferably substantially equal to 90°.

[0044] Preferably, the angle AT is in the range of 30° to 37°, preferably 30° to 35° in absolute value. The inventors behind the present invention have noted that by using a relatively large angle AT, that is, an angle greater than or equal to 30°, the shear stiffness of the crown of the tire is improved compared to a smaller angle.

[0045] Nevertheless, using an angle AT that is too large, that is, greater than 37°, results in this reduction in circumferential stiffness and an increase in tire noise. Therefore, it is preferable not to use an angle AT that is too large. The inventors have recognized that using an angle AT that is too large within the scope of the present invention reduces the contribution of the actuating layer to the circumferential stiffness due to the projection of the force generated circumferentially by the actuating layer being small. Furthermore, the inventors have recognized that an angle AT that is too large within the scope of the present invention also contributes to an increase in noise because the vibration response increases compared to a more moderate angle AT.

[0046] In embodiments in which each bead is provided with a circumferential reinforcing element so that a carcass layer can be easily fixed to each bead, after the step of arranging the carcass assembly and before the step of arranging the actuating assembly, - Two circumferential reinforcing elements are arranged around the carcass assembly, - Since each axial edge of the carcass assembly is folded axially inwards, the carcass assembly is wound axially around each circumferential reinforcing element.

[0047] In these embodiments where the carcass layer is axially delimited by two axial edges of the carcass layer and comprises a carcass fibrous reinforcing element extending axially from one axial edge of the carcass layer to the other axial edge, and the carcass layer is wound around the circumferential reinforcing element, the main direction of each carcass fibrous reinforcing element is the circumferential direction of the tire and, - Forms an angle ACS, which is strictly less than 80° in absolute value, in the axial central part of the carcass layer extending axially radially aligned with the working layer, - Forms an angle ACF, which is in the range of 80° to 90°, preferably 85° to 90°, and more preferably substantially equal to 90° in absolute value, in each axial transverse part of the carcass layer extending axially between the axial central part of the carcass layer and each axial edge, and each axial transverse part is wound around each circumferential reinforcing element.

[0048] In the above method, the initial angle formed by the main directions of the carcass and the working fibrous reinforcing element with the circumferential direction of the support changes during the deformation stage to reach their final angles and the angles in the tire, except for each axial transverse part wound around the circumferential reinforcing element. In each axial transverse part, the main direction of the carcass fibrous reinforcing element remains substantially the same with respect to the circumferential direction of the support and thus the circumferential direction of the tire.

[0049] Furthermore, by maintaining the initial angle A3 in each axial transverse part and maintaining an angle ACS, which is strictly less than 80° in absolute value, in the axial central part, the tire has the characteristics of a radial tire imparted by the radial carcass fibrous reinforcing elements in the sidewalls and the characteristics of a tire provided with a triangular split crown reinforcement.

[0050] In an embodiment having a transition zone where the main direction of each carcass fibrous reinforcing element is substantially variable in angle between the axial center portion and the axial lateral portion, the axial center portion is equal to at least 40%, preferably at least 50% of the axial width of the working layer, and has an axial width equal to at most 90%, preferably at most 80% of the axial width of the working layer. Preferably, the median plane of the tire 10 intersects this axial center portion. More preferably, this axial center portion of the carcass layer or each carcass layer is arranged with the median plane of the tire as the axial center. The axial width of the axial center portion depends in particular on the degree of deformation and the initial angle. A person skilled in the art will know how the axial width of the axial center portion changes by changing one and / or the other of these parameters.

[0051] In these embodiments having a transition zone where the main direction of each carcass fibrous reinforcing element is substantially variable in angle between the axial center portion and the axial lateral portion, each axial lateral portion is equal to at least 50% of the radial height of the tire, and has a radial height equal to at most 100% of the radial height of the tire. Preferably, the equatorial circumferential surface of the tire intersects each axial lateral portion. Similar to the axial center portion, the radial height of each axial lateral portion depends in particular on the degree of deformation and the initial angle. A person skilled in the art will know how the radial height of each axial lateral portion changes by changing one and / or the other of these parameters.

[0052] For most passenger car tire sizes, starting from an initial angle A3 in the range of 80° to 90° in absolute value and obtaining an angle AT in the range of 27° to 40° in absolute value, the angle ACS will be in the range of 50° to 75° in absolute value.

[0053] According to the present invention, when the initial angle A3 is in the range of 80° to 90° in absolute value, the axial portions of the carcass fibrous reinforcing elements present in the central portion in the axial direction of the carcass assembly are subjected to rotation, resulting in a decrease in the angle formed by their main directions. This angle decrease depends on the degree of deformation and the initial angle formed by the main direction of each active fibrous reinforcing element with the circumferential direction of the support before the deformation stage. The degree of deformation is determined in a manner known to those skilled in the art depending on the axial withdrawal of the axial edges of the carcass assembly from each other and the radial expansion of the assembly between its cylindrical and annular shapes. The determination of the initial angle according to the final angle or vice versa depends on the degree of deformation in a manner known to those skilled in the art as described in FR2797213 and FR1413102.

[0054] In an embodiment in which each axial transverse portion is wound around each circumferential reinforcing element, each axial transverse portion of the carcass layer is - an inner axial transverse portion axially arranged between the axial central portion and each circumferential reinforcing element, the main direction of each carcass fibrous reinforcing element forming an angle ACF1 with the circumferential direction of the tire, and said inner axial transverse portion - an outer axial transverse portion axially arranged between each circumferential reinforcing element and each axial edge of the carcass layer, the main direction of each carcass fibrous reinforcing element forming an angle ACF2 opposite to the angle ACF1 such that |ACF1 - ACF2 - 180| ≤ 20°, preferably |ACF1 - ACF2 - 180| ≤ 10°, more preferably |ACF1 - ACF2 - 180| is substantially zero, with the circumferential direction of the tire, and said outer axial transverse portion It is preferable to include. The inner axial transverse portion is arranged axially inside the outer axial transverse portion.

[0055] Starting from the initial angle A3 according to the present invention, each angle ACF1 and ACF2 is in the range of 80° to 90° in absolute value, preferably 85° to 90°, and more preferably substantially equal to 90°.

[0056] To obtain the angles ACS and ACF, a method is used of deforming an assembly having a substantially cylindrical shape so as to obtain an assembly having a substantially annular shape, in which case, following the deformation step, the main direction of each carcass fibrous reinforcing element is the circumferential direction of the support and, - forming a final angle B3S which is strictly less than 80° in absolute value at the axial central part of the carcass assembly which extends axially radially alongside the actuating assembly and is intended to form the axial central part of the carcass layer, - forming a final angle B3F which ranges from 80° to 90° in absolute value, preferably from 85° to 90°, and more preferably is substantially equal to 90° at two axial transverse parts of the carcass assembly which extend axially between the axial central part of the carcass layer and each axial edge and are intended to form each axial transverse part of the carcass layer.

[0057] In most embodiments, no step between the deformation step and the crosslinking step results in a variation in the angle B3S. As a result, the final angle B3S is substantially equal to the angle ACS. Thus, B3S ranges from 50° to 75° in absolute value.

[0058] In other embodiments, a slight decrease in the final angle B3S may occur at any step between the deformation step and the crosslinking step, for example, during the step of shaping the green form in a mold, during which the green form undergoes radial and circumferential shaping deformations which cannot be ignored compared to the deformations received during the deformation step.

[0059] In certain embodiments which use steps between the deformation step and the crosslinking step, the method comprises the following steps: - a step in which the green form of the tire obtained from an assembly having a substantially annular shape is shaped by expanding the green form radially and circumferentially, - a step of crosslinking the expanded green form which has a substantially annular shape to obtain the tire.

[0060] Preferably, before the crosslinking stage, a strip of polymer material intended to form the tread is arranged radially outside the working assembly so as to form a green shape.

[0061] To obtain the angle AT for most passenger car tire sizes, when the working assembly comprises working fibrous reinforcing elements which are axially delimited by its two axial edges and extend axially substantially parallel to each other from one axial edge of the working assembly to the other axial edge of the working assembly, each working fibrous reinforcing element is used in such a way that it extends along the main direction of each working fibrous reinforcing element which forms an initial angle A2 in the range from 25° to 50° with the circumferential direction of the support in the working assembly. Implicitly, the initial angle A2 is constant when moving axially from one axial edge of the working assembly to the other axial edge of the working assembly.

[0062] In most embodiments where any stage between the deformation stage and the crosslinking stage does not cause a variation in the final angle B2 formed by the main direction of each carcass fibrous reinforcing element with the circumferential direction of the support after the deformation stage, the final angle B2 is substantially equal to the angle AT. Thus, since the assembly 58 having a substantially cylindrical shape around the main axis of the support is deformed to obtain an assembly having a substantially annular shape around the main axis A of the support, after the deformation stage, the main direction of each working fibrous reinforcing element 340 forms a final angle B2 in the range from 27° to 40°, preferably from 30° to 37°, more preferably from 30° to 35° in absolute value with the circumferential direction of the support.

[0063] In one embodiment capable of manufacturing a tire comprising a hoop reinforcement arranged radially outside the working reinforcement, following the deformation stage, a hooping assembly intended to form the hoop reinforcement is arranged radially around an assembly having a substantially annular shape around the main axis of the support, and this hooping assembly is formed by spirally winding a hoop ply obtained by embedding one or more hooping fibrous reinforcing elements or one or more hoopink fibrous reinforcing elements in an elastomer matrix.

[0064] During this method step, the step of arranging the hoop assembly is performed such that each hoop fibrous reinforcing element extends axially between two axial edges 76A, 76B of the hoop assembly along the main direction K1 of each hoop fibrous reinforcing element. The angle formed by the main direction of each hoop fibrous reinforcing element and the circumferential direction of the support is advantageously less than or equal to 10° in absolute value, preferably less than or equal to 7°, more preferably less than or equal to 5°.

[0065] Tire according to the present invention

[0066] The tire according to the invention is obtained using the method as defined above.

[0067] In an embodiment that makes it possible to improve the performance of the tire, in particular the cornering stiffness and the performance at high speeds, the tire comprises a hoop reinforcement arranged radially outside the working reinforcement, the hoop reinforcement being axially delimited by its two axial edges and having at least one hoop fibrous reinforcing element wound helically circumferentially so as to extend axially between the axial edges of the hoop reinforcement along a main direction forming an angle AF less than or equal to 10° in absolute value, preferably less than or equal to 7°, more preferably less than or equal to 5° with the circumferential direction of the tire. Thus, the hoop reinforcement is inserted radially between the working reinforcement and the tread.

[0068] In a variant, the carcass reinforcement comprises a single carcass layer. In this variant, except for the single carcass layer, the carcass reinforcement does not have a layer reinforced by fibrous reinforcing elements. Such fibrous reinforcing elements of the reinforcing layer excluded from the carcass reinforcement of the tire comprise metallic fibrous reinforcing elements and fabric fibrous reinforcing elements. Very preferably, the carcass reinforcement consists of a single carcass layer.

[0069] In another variant, the carcass reinforcement comprises two carcass layers, and the main directions of the carcass fibrous reinforcing elements with respect to the two carcass layers are substantially parallel to each other.

[0070] In the tire according to the invention, the crown comprises a tread and a crown reinforcement. The tread is - directed radially outwards by a surface intended to come into contact with the road surface, and - directed radially inwards by the crown reinforcement, and is understood to be a strip of polymer material, preferably an elastomeric material, which is delimited.

[0071] The strip of polymer material is composed of a layer of polymer material, preferably an elastomeric material, or is composed of a stack of several layers, each layer being composed of a polymer material, preferably an elastomeric material.

[0072] In an advantageous embodiment, the crown reinforcement comprises a single hoop reinforcement and a single working reinforcement. Thus, apart from these hoop reinforcements and working reinforcements, the crown reinforcement does not have a reinforcement reinforced by fibrous reinforcing elements. The fibrous reinforcing elements of such a reinforcement excluded from the crown reinforcement of the tire comprise metallic fibrous reinforcing elements and fabric fibrous reinforcing elements. Very preferably, the crown reinforcement is composed of a hoop reinforcement and a working reinforcement.

[0073] In a very preferred embodiment, apart from the crown reinforcement, the crown does not have a reinforcement reinforced by fibrous reinforcing elements. The fibrous reinforcing elements of such a reinforcement excluded from the crown of the tire comprise metallic fibrous reinforcing elements and fabric fibrous reinforcing elements. Very preferably, the crown is composed of a tread and a crown reinforcement.

[0074] In a highly preferred embodiment, the carcass reinforcement is arranged to be in direct radial contact with the crown reinforcement, and the crown reinforcement is arranged to be in direct radial contact with the tread. In this highly preferred embodiment, it is advantageous for the hoop reinforcement and the working layer to be arranged to be in direct radial contact with each other.

[0075] The expression "in direct radial contact" means that the objects in question that are in direct radial contact, in this case the layers, reinforcements, or tread, are not radially separated by any object, such as a layer, reinforcement, or strip that is radially interposed between the said objects that are in direct radial contact with each other.

[0076] Preferably, in order to ensure an effective triangulation of the crown of the tire, the main direction of the said or each hoop-like reinforcing element, the main direction of each working fibrous reinforcing element, and the main direction of each carcass fibrous reinforcing element form an angle with a different pair in the circumferential direction of the tire in the part of the tire that is axially located between the axially narrowest layer or reinforcement among the working layer and the hoop reinforcement and the axial edges thereof. This is also called a triangular mesh formed by the hoop, working, and carcass fibrous reinforcing elements.

[0077] In other words, in the case of the said or each hoop-like reinforcing element extending along the hoop main direction, each working fibrous reinforcing element extending along the working main direction, and each carcass fibrous reinforcing element extending along the carcass main direction, these hoop main direction, working main direction, and carcass main direction exist in different pairs in the part of the tire axially delimited by the axial edges of the axially narrowest layer or reinforcement among the working layer and the hoop reinforcement.

[0078] To further improve the triangulation of the crown of the tire, the main direction of each working fibrous reinforcing element and the main direction of each carcass fibrous reinforcing element form an angle with the circumferential direction of the tire in the part of the tire that is axially located between the axial edges of the working layer, and the directions of the angles are opposite.

[0079] Advantageously, the fibrous reinforcing elements of each layer are embedded in an elastomeric matrix. Different layers can comprise the same or different elastomeric matrices.

[0080] The elastomeric matrix means a matrix that exhibits elastomeric behavior in a crosslinked state. Such a matrix is advantageously obtained by crosslinking a composition comprising at least one elastomer and at least one other component. Preferably, the composition comprising at least one elastomer and at least one other component comprises an elastomer, a crosslinking system, and a filler. The compositions used for these layers are typically conventional compositions for natural rubber or some other diene elastomer, a reinforcing filler such as carbon black, a vulcanization system, and conventional additives-based calendered reinforcement. The adhesion between the fibrous reinforcing elements and the matrix in which they are embedded is ensured, for example, by conventional adhesive compositions, such as RFL-type adhesives or equivalent adhesives.

[0081] Advantageously, each actuating fibrous reinforcing element is metallic. A metallic fibrous element is understood, by definition, to be a fibrous element formed from one single fiber made entirely (100% of the thread) of a metallic material or from an assembly of a plurality of elementary single fibers. Such metallic fibrous elements are preferably implemented using fine wires made of steel, more preferably pearlite (or ferrite - pearlite) carbon steel, hereinafter referred to as "carbon steel", or fine wires made of stainless steel (by definition, stainless steel comprises at least 11% chromium and at least 50% iron). However, it is of course possible to use other steels or other alloys. When advantageously using carbon steel, its carbon content (weight % of the steel) is preferably in the range of 0.05% to 1.2%, particularly from 0.5% to 1.1%, and these contents represent a good compromise between the mechanical properties required for the tire and the feasibility of the fine wire. The metal or steel used can be coated with itself in a metallic layer, thereby improving, for example, the workability of the metal cord and / or its components, or the grip properties, corrosion resistance, or wear properties of the cord and / or the tire itself, such as aging resistance. According to a preferred embodiment, the steel used is coated with a layer of brass (Zn - Cu alloy) or zinc. Each metallic elementary single fiber is preferably made of carbon steel, as described above, and has a mechanical strength in the range of 1000 MPa to 5000 MPa. Such mechanical strength corresponds to the steel grades commonly encountered in the field of tires, namely NT (normal tensile), HT (high tensile), ST (super - tensile), SHT (super - high tensile), UT (ultra - tensile), UHT (ultra - high tensile) and MT (mega - tensile), and by using a high mechanical strength, it is potentially possible to improve the reinforcement of the base material intended to be embedded with the cord and to lighten the base material thus reinforced. One elementary single fiber or an assembly of a plurality of elementary single fibers can be coated with a polymeric material, as described, for example, in US2016 / 0167438.

[0082] That the angles AT, ACS, ACF, ACF1, ACF2, and AF characterize the angles in the final tire, that the angles A1, A2, A3 characterize the angles before the deformation stage, and that the angles B2, B3S, B3F characterize the angles after the deformation stage and before the crosslinking stage will be easily understood in light of the summary of abnormalities and the description of the following drawings.

[0083] The present invention and its advantages will be easily understood in light of the following detailed description and non-limiting exemplary embodiments and from FIGS. 1 to 14 related to these examples.

Brief Description of the Drawings

[0084]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

DETAILED DESCRIPTION OF THE INVENTION

[0085] A coordinate system X, Y, Z corresponding to the normal circumferential direction (X), axial direction (Y), and radial direction (Z) of the tire respectively is shown in the figure related to the tire. Regarding a manufacturing support that is deformable between a substantially cylindrical shape and an annular shape around the axis y, a coordinate system x, y, z corresponding to the normal circumferential direction (x), axial direction (y), and radial direction (z) respectively is shown in the figure related to the method.

[0086] FIG. 1 shows a tire denoted by the general reference number 10 according to the invention. The tire 10 substantially exhibits rotational symmetry with respect to an axis substantially parallel to the axial direction Y. The tire 10 is for a passenger car in this case and has a size of 245 / 45R18.

[0087] The tire 10 includes a crown 12, and the crown 12 includes a tread 20 intended to contact the road surface during running and a crown reinforcement 14 extending along the circumferential direction X within the crown 12. The tire 10 also includes an airtight layer 15 for gas for inflation, and this airtight layer is intended to delimit an internal cavity closed by the mounting support of the tire 10 when the tire 10 is mounted on a mounting support, for example, a rim.

[0088] The crown reinforcement 14 includes a single-acting reinforcement 16 having an actuating layer 18 and a single-hoop reinforcement 17 having a single-hooping layer 19. In this case, the actuating reinforcement 6 has a single actuating layer 18 and, in this particular case, is composed of the single actuating layer 18. In the following description, for the sake of brevity, with respect to the actuating layer 18, it will be referred to without repeating each time that it is a single layer. The hoop reinforcement 17 is composed of the hooping layer 19.

[0089] The crown reinforcement 14 radially supports the tread 20. In this case, the hoop reinforcement 17, in this example the hooping layer 19, is arranged radially outside the actuating reinforcement 16 and is thus inserted radially between the actuating reinforcement 16 and the tread 20. In the embodiments shown in FIGS. 1 and 2, the hoop reinforcement 17 has an axial width smaller than the axial width of the actuating layer 18. Thus, the hoop reinforcement 17 is the one with the smaller axial width among the actuating layer 18 and the hoop reinforcement 17.

[0090] The tire 10 includes two sidewalls 22 that extend radially inwardly of the crown 12. The tire 10 also has two beads 24 radially inside the sidewalls 22. Each sidewall 22 connects each bead 24 to the crown 12.

[0091] Each bead 24 includes at least one circumferential reinforcement element 26, in this example, a bead wire 28 on which a mass of filling rubber 30 is radially supported.

[0092] The tire 10 includes a carcass reinforcement 32 fixed to each bead 24. The carcass reinforcement 32 extends inside each sidewall 22 and radially inside the crown 12. The crown reinforcement 14 is arranged radially between the tread 20 and the carcass reinforcement 32.

[0093] The carcass reinforcement 32 comprises a single carcass layer 34. In this case, the carcass reinforcement 32 comprises a single carcass layer 34 and, in this particular case, is constituted by the single carcass layer 34. In this embodiment, for the sake of simplicity, reference is made to the carcass layer 34 without having to state each time that it is a single layer.

[0094] The carcass reinforcement 32 is arranged to be in direct radial contact with the crown reinforcement 14. The crown reinforcement 14 is arranged to be in direct radial contact with the tread 20. The hoop reinforcement 17 and the working layer 18 are arranged to be in direct radial contact with each other.

[0095] Reference is now made to FIGS. 1 to 4 with respect to the hooping layer 19, the working layer 18, and the carcass layer 34.

[0096] The hoop reinforcement 17, in this case the hooping layer 19, is axially delimited by two axial edges 17a, 17b of the hoop reinforcement 17. The hoop reinforcement 17 comprises a plurality of hooping fibrous reinforcement elements 170 which are wound helically in the circumferential direction so as to extend axially between the axial edge 17A and the other axial edge 17B of the hooping layer 17 along the main direction D1 of each hooping fibrous reinforcement element 170. The main direction D1 forms an angle AF with the circumferential direction X of the tire 10 which is less than or equal to 10° in absolute value, preferably less than or equal to 7°, more preferably less than or equal to 5°. In this case, AF = -5°.

[0097] The actuating layer 18 is axially delimited by two axial edges 18A, 18B of the actuating layer 18. The actuating layer 18 comprises actuating fibrous reinforcing elements 180 that extend axially in a substantially parallel manner to one another from one axial edge 18A of the actuating layer 18 to the other axial edge 18B of the actuating layer 18. Each actuating fibrous reinforcing element 180 extends along a main direction D2 of each actuating fibrous reinforcing element 180. The direction D2 forms an angle AT with the circumferential direction X of the tire 10 that is strictly greater in absolute value than 10°, preferably in the range from 27° to 40°, preferably in the range from 30° to 37°, more preferably in the range from 30° to 35°. In this case, AT = -35°.

[0098] The carcass layer 34 is axially delimited by two axial edges 34A, 34B of the carcass layer 34. The carcass layer 34 comprises carcass fibrous reinforcing elements 340 that extend axially from the axial edge 34A to the other axial edge 34B (not shown) of the carcass layer 34. The carcass layer 34 comprises an axially central portion 34S that extends axially radially alongside the actuating layer 18, and two axially transverse portions 34F that extend axially between the axially central portion 34S and each of the axial edges 34A, 34B. Each axially transverse portion 34F is wound around each circumferential reinforcing element 26. Each axially transverse portion 34F comprises an inner axially transverse portion 38 that is axially disposed between the axially central portion 34S and each circumferential reinforcing element 26, and an outer axially transverse portion 40 that is axially disposed between each circumferential reinforcing element 26 and each axial edge 34A, 34B of the carcass layer 34. Lumps of filling rubber 30 are inserted between the inner and outer axially transverse portions 38, 40.

[0099] Each carcass fibrous reinforcing element 340 extends along a main direction D3 of each carcass fibrous reinforcing element 340, and that direction forms an angle ACS with the circumferential direction X of the tire 10 that is strictly less than 80° in absolute value at the axially central portion 34S of the carcass layer 34. Advantageously, at this axially central portion 34S of the carcass layer 34, the main direction D3 of each carcass fibrous reinforcing element 340 forms an angle ACS with the circumferential direction X of the tire 10 that is in the range from 50° to 75° in absolute value. In this case, ACS = +65°.

[0100] The axial center portion 34S of the carcass layer 34 is equal to at least 40%, preferably at least 50%, of the axial width L of the working layer 18 and has an axial width equal to at most 90%, preferably at most 80%, of the axial width L of the working layer 18. In this particular case, it has an axial width equal to 60% of the working layer 18. The median plane M of the tire 10 intersects this portion 34S. More preferably, this portion 34S is arranged with the median plane M of the tire 10 as the axial center.

[0101] As shown in FIGS. 1 and 3, the main direction D3 of each carcass fibrous reinforcing element 340 forms an angle ACF with the circumferential direction X of the tire 10. This angle is in the range of 80° to 90°, preferably 85° to 90°, in absolute value at each axial lateral portion 34F of the carcass layer 34 extending radially at each sidewall 22, and more preferably is substantially equal to 90°. In this case, ACF = +90°.

[0102] Each portion 34F of the carcass layer 34 extending radially at each sidewall 22 has a radial height equal to at least 50% of the radial height H of the tire 10 and at most 100% of the radial height H of the tire 10. In this particular case, it has a radial height equal to 95% of the radial height H of the tire 10. The equatorial circumferential surface E of the tire 10 intersects each portion 34F of the carcass layer 34 located at each sidewall 22.

[0103] The main direction D3 of each carcass fibrous reinforcing element 340 forms an angle ACF1 with the circumferential direction X of the tire 10 at each inner axial lateral portion 38 and an angle ACF2 at each outer axial lateral portion 40. The angles ACF1 and ACF2 have opposite directions. Each angle ACF1 and ACF2 is in the range of 80° to 90°, preferably 85° to 90°, in absolute value, and more preferably is substantially equal to +90° and -90° respectively. Note that |ACF1 - ACF2 - 180| ≦ 20°, preferably |ACF1 - ACF2 - 180| ≦ 10°, and in this case, |ACF1 - ACF2 - 180| is substantially zero.

[0104] As shown in FIG. 2, the main direction D2 of each actuating fibrous reinforcing element 180 and the main direction D3 of each carcass fibrous reinforcing element 340 form angles AT and ACS of opposite directions with the circumferential direction X of the tire 10 in a portion PS of the tire 10 that is axially located between the axial edges 18A, 18B of the actuating layer 18. Specifically, in this case, AT = -35° and ACS = +65°. Further, the main direction D1 of each hoop reinforcing fibrous material 170, the main direction D2 of each actuating fibrous reinforcing element 180, and the main direction D3 of each carcass fibrous reinforcing element 340 form angles that form a pair with different absolute values with the circumferential direction X of the tire 10 in a portion PS' of the tire 10 that is axially located between the axial edges 17A, 17B of the hoop reinforcement 17.

[0105] Generally and particularly in the described embodiment, each portion PS, PS' of the tire 10 is equal to at least 40%, preferably at least 50% of the axial width L of the actuating layer 18, and has an axial width equal to a maximum of 90%, preferably a maximum of 80% of the axial width L of the actuating layer 18, and in this particular case has an axial width equal to 60% of the actuating layer 18. The median plane M of the tire 10 intersects each portion PS, PS' of the tire 10. More preferably, each portion PS, PS' of the tire 10 is arranged with the median plane M of the tire 10 as the axial center.

[0106] Each actuating fibrous reinforcing element 180 is an assembly of two steel single fibers each having a diameter equal to 0.30 mm, and the two steel single fibers are wound around each other with a pitch of 14 mm.

[0107] Each carcass fibrous reinforcing element 340 conventionally comprises two multi-fiber strands, each multi-fiber strand comprising a spun yarn of polyester single fibers, here PET. These two multi-fiber strands are each over-twisted at 240 turns per meter in one direction and then twisted at 240 turns per meter in the opposite direction. These two multi-fiber strands are wound around each other in a helical manner. Each of these multi-fiber strands has a count equal to 220 tex.

[0108] Each hoop-shaped fibrous reinforcing element 170 is of the type described, for example, in WO2016 / 166056 A1.

[0109] The tire 10 is obtained by the method according to the invention, and the method will be described with reference to FIGS. 5 to 14.

[0110] First, the actuating assembly 50 and the carcass assembly 52 are produced by arranging the fibrous reinforcing elements 180 and 340 of each assembly 50 and 52 parallel to each other and embedding them in an uncrosslinked composition comprising at least one elastomer, for example, by skim coating, this composition being intended to form an elastomeric matrix in a crosslinked state. A ply known as a straight ply is obtained in which the fibrous reinforcing elements are parallel to each other and parallel to the main direction of the ply.

[0111] Next, with respect to the actuating ply, each part of the straight actuating ply is cut at a cutting angle and these parts are butted against each other to obtain an actuating ply known as an inclined actuating ply, in which case the actuating fibrous reinforcing elements are parallel to each other and form an angle equal to the cutting angle with the main direction of the actuating ply.

[0112] With respect to the carcass ply, each part of the straight carcass ply is cut perpendicular to the main direction of the straight carcass ply and these parts are butted against each other to obtain a carcass ply known as an inclined carcass ply, in which case the carcass fibrous reinforcing elements are parallel to each other and form an angle in the range of 80° to 90° equal to the cutting angle with the main direction of the carcass ply.

[0113] In the embodiment to be described, a single actuating ply 49 and a single carcass ply 51 are obtained, and the axial width of each of them, i.e., the dimension along the direction perpendicular to the longitudinal edges of each ply, is respectively equal to the axial width of each of the actuating assembly 50 and the carcass assembly 52 to be formed later.

[0114] Referring to FIG. 5, in the first stage of assembling the raw tire form, a sealing assembly 72 is formed which is intended to form a sealing layer 15 by arranging a sealing ply 70 around a support 60 having a substantially cylindrical shape with respect to its main axis A. In this case, the sealing ply 70 is arranged by winding the sealing ply 70. The support 60 has a substantially cylindrical laying surface with a radius equal to 235 mm.

[0115] Next, referring to FIG. 6, a carcass assembly 52 intended to form a carcass layer 34 on the radially outer side of the sealing assembly 72 is arranged around the support 60. In this particular case, to form the carcass assembly 52, the carcass assembly 52 is arranged by winding a carcass ply 51 around the support 60. The carcass assembly 52 is axially delimited by two axial edges 52A, 52B of the carcass assembly 52 and comprises carcass fibrous reinforcing elements 340 which extend axially substantially parallel to each other from one axial edge 52A of the carcass assembly 52 to the other axial edge 52B of the carcass assembly 52. Each carcass fibrous reinforcing element 340 extends along the main direction K3 of each carcass fibrous reinforcing element 340 in the carcass assembly 51 in the carcass assembly 52. The main direction K3 forms an initial angle A3 of each carcass fibrous reinforcing element 340 in the range of 80° to 90° in absolute value with the circumferential direction x of the support 60, preferably in the range of 85° to 90°, and in this case is substantially equal to 90°.

[0116] Next, referring to FIGS. 7 and 8, two circumferential reinforcing elements 26 are arranged around the carcass assembly 52 by folding each axial edge 52A, 52B of the carcass assembly 52 axially inwards so as to cover each circumferential reinforcing element 26 radially at each axial edge 52A, 52B of the carcass assembly 52 and such that the carcass assembly 52 is wound around each circumferential reinforcing element 26 axially therearound.

[0117] FIG. 9 shows the arrangement of the carcass fibrous reinforcing element 340 after the step of axially folding the axial edges 52A, 52B of the carcass assembly 52 around the circumferential reinforcing element 26. The initial angle A3 described above is shown in this FIG. 9.

[0118] Next, referring to FIG. 10, an actuating assembly 50 intended to form the actuating layer 18 is disposed radially outside the carcass assembly 52. In this particular case, the actuating assembly is disposed by radially winding the actuating ply 49 radially outside the carcass assembly 52 so as to form the actuating assembly 50. The actuating assembly 50 is axially delimited by two axial edges 50A, 50B of the actuating assembly 50, and includes actuating fibrous reinforcing elements 180 that extend axially substantially parallel to each other from one axial edge 50A of the actuating assembly 50 to the other axial edge 50B. Each actuating fibrous reinforcing element 180 extends along the main direction K2 of each actuating fibrous reinforcing element 180 in the actuating assembly 50. Referring to FIG. 11, the main direction K2 forms an initial angle A2 of each actuating fibrous reinforcing element 180 in the range of 25° to 50° in absolute value with the circumferential direction x of the support 60. In this case, A2 = -39°.

[0119] The carcass assembly 52 and the actuating assembly 50 then form an assembly 58 having a substantially cylindrical shape around the main axis A of the support 60.

[0120] FIG. 11 shows a view similar to that of FIG. 9 illustrating the arrangement of the carcass fibrous reinforcing element 340 and the actuating fibrous reinforcing element 180 after the step of forming the actuating assembly 50. The initial angles A2 and A3 are shown in this FIG. 11.

[0121] Next, an assembly 58 having a substantially cylindrical shape around the main axis A of the support 60 is deformed to obtain an assembly 58 having a substantially annular shape around the main axis A of the support 60. The deformed assembly 58 shown in FIG. 12 is obtained. In that case, the laying surface of the support 60 has a radius equal to 327 mm on the central plane of the support.

[0122] Referring to FIG. 13, since an assembly 58 having a substantially cylindrical shape around the main axis A of the support 60 is deformed to obtain an assembly 58 having a substantially annular shape around the main axis A of the support 60, after the deformation step, the main direction K3 of each carcass fibrous reinforcement element 340 forms the circumferential direction x of the support 60 and the final angle B3S of each carcass fibrous reinforcement element 340, and this angle is strictly less than 80° in absolute value at the axial central portion 52S of the carcass assembly 52 extending axially side by side with the actuating assembly 50 in the radial direction. Advantageously, the final angle B3S is in the range of 50° to 75° in absolute value. In this case, B3S = +65°. The portion 52S of the carcass assembly 52 is intended to form the axial central portion 34S of the carcass layer 34.

[0123] Since an assembly 58 having a substantially cylindrical shape around the main axis A of the support 60 is deformed to obtain an assembly 58 having a substantially annular shape around the main axis A of the support 60, similarly after the deformation step, the main direction K3 of each carcass fibrous reinforcement element 340 forms the circumferential direction x of the support 60 and the final angle B3F of each carcass fibrous reinforcement element 340, and this angle is in the range of 80° to 90° in absolute value at the two axial transverse portions 52F of the carcass assembly 52 extending axially between the axial central portion 52S and the axial edges 52A, 52B of the carcass assembly 52. Each axial transverse portion 52F of the carcass assembly 52 is intended to form the axial transverse portion 34F of the carcass layer 34. In this case, B3F = +90°.

[0124] The assembly 58, which substantially has a cylindrical shape around the main axis A of the support 60, is deformed to obtain an assembly 58 that substantially has an annular shape around the main axis A of the support 60. Thus, similarly after the deformation stage, the main direction K2 of each active fibrous reinforcing element 340 forms the circumferential direction x of the support 60 and the final angle B2 of each active fibrous reinforcing element 340, and this angle is strictly greater in absolute value than 10°. Advantageously, the final angle B2 is in the range from 27° to 40° in absolute value, preferably from 30° to 37°, more preferably from 30° to 35°. In this case, B2 = -35°.

[0125] The main direction K2 of each active fibrous reinforcing element 180 and the main direction K3 of each carcass fibrous reinforcing element 340 form the final angles B2 and B3S, which have opposite directions, with the circumferential direction x of the support 60 at the portion AC of the assembly 58 that is axially located between the axial edges 50A, 50B of the actuating assembly 50. Specifically, in this case, B2 = -35° and B3S = +65°.

[0126] As shown in FIG. 14, the hooping assembly 76, which is intended to form the hoop reinforcement 17, is arranged radially around the pre-formed assembly 58 on the support 60. In this case, the hooping assembly 76 is formed by spirally winding the hooping ply 75 on an annular shape. Next, the hooping assembly 76 is moved radially outside the pre-formed assembly 58 with the aid of a transfer ring. In the deformation, in order to form the hooping assembly 76, the hooping ply 74 can be directly spirally wound circumferentially around the pre-formed assembly 58. The hooping ply 74 is manufactured in the same way as the carcass ply 51 and the actuating ply 49 by embedding the hooping fibrous reinforcing element 170 in an elastomeric matrix.

[0127] In the illustrated embodiment, the hooping assembly 76 has an axial width that is smaller than the axial width of the actuating assembly 50. Thus, the hooping assembly 74 is the narrower one axially among the actuating assembly 50 and the hooping assembly 76.

[0128] The step of arranging the hoop assembly 76 is performed such that each hoop fibrous reinforcing element 170 extends axially between two axial edges 76A, 76B of the hoop assembly 76 along the main direction K1 of each hoop fibrous reinforcing element 170. The angle formed by the main direction K1 of each hoop fibrous reinforcing element 170 with the circumferential direction x of the support 60 is less than or equal to 10° in absolute value, preferably less than or equal to 7°, more preferably less than or equal to 5°.

[0129] The angle A1 formed by the main direction K1 of each hoop fibrous reinforcing element 170 with the circumferential direction x of the support 60 is less than or equal to 10° in absolute value, preferably less than or equal to 7°, more preferably less than or equal to 5°, and in this case is equal to 5°.

[0130] The main direction K1 of each hoop fibrous reinforcing material 170, the main direction K2 of each actuating fibrous reinforcing element 180, and the main direction K3 of each carcass fibrous reinforcing element 340 form angles with the circumferential direction x of the support 60 that are different in absolute value in the assembly 58 and a portion AC' (not shown) of the hoop assembly 76 that are axially located between the axial edges 76A, 76B of the hoop assembly 76.

[0131] Next, in order to form the green form of the tire 10, a strip of polymeric material intended to form the tread 20 is disposed radially outside the actuating assembly 50, in this case radially outside the hoop assembly 76.

[0132] In a preferred variant not shown, the hoop assembly 76 can be arranged on the annular form, and then a strip of polymer material intended to form the tread 20 can be arranged radially outside the hoop assembly 76 to form an intermediate assembly, and then this intermediate assembly can be transferred radially outside the assembly 58 formed on the support 60 previously.

[0133] Next, the green form of the tire 10 obtained from the pre-formed assembly 58, from the hoop assembly 76, and from the strip of polymer material is shaped by expanding it radially and circumferentially.

[0134] Next, to obtain the tire 10, the expanded green form having a substantially annular shape is crosslinked, for example, by vulcanization.

[0135] Comparative test

[0136] The circumferential stiffness Rxx and the shear stiffness Gxy of different tires T1 and T2 not according to the present invention and tires P1, P2, P3, P4, P5 according to the present invention were simulated. The results are shown on a base 100 such that values greater than 100 with respect to the circumferential stiffness Rxx and the shear stiffness Gxy indicate an improvement in these stiffnesses.

[0137] Tire T1 is tire S2 described in EP3489035. Tire P3 is the above-described tire 10. All the tires are identical except for the angles A3, A2, ACS, and AT, and their values are collated in Table 1 below. TIFF0007713002000001.tif51153 Table 1

[0138] As described above, the angles AT and ACS have little effect on the circumferential stiffness Rxx. The shear stiffness Gxy is either little affected (tires P1 and P5) or improved for larger angles AT (tires P2, P3, and P4). Nevertheless, tires P1 to P5 have the undeniable advantage of all being manufactured from a single carcass ply with the angle A3 in the range of 80° to 90° and not requiring the step of cutting at a specific angle according to the size of the tire.

[0139] The present invention is not limited to the above-described embodiments.

[0140] Specifically, it is considered possible to easily assume a tire similar to the above-described one and having a carcass reinforcement with two carcass layers.

[0141] The present invention can also be implemented without a carcass layer having an axial lateral portion wound around each circumferential reinforcement element. In fact, other methods of fixing the carcass layer 34, such as those described in, for example, US5702548, are possible.

Claims

1. A tire (10) comprising a crown (12), two sidewalls (22), and two beads (24), each sidewall (22) connecting each bead (24) to the crown (12), the tire (10) comprising a carcass reinforcement (32) fixed to each bead (24) and extending radially inwardly within each sidewall (22) and within the crown (12), the carcass reinforcement (32) comprising at least one carcass layer (34), the crown (12) being - A tread (20) intended to contact the road surface when the tire (10) is running, - A crown reinforcement (14) disposed radially between the tread (20) and the carcass reinforcement (32), the crown reinforcement (14) comprising an active reinforcement (16) having a single active layer (18), the active layer (18) being axially delimited by two axial edges (18A, 18B) of the active layer (18) and along the main direction (D2) of each active fibrous reinforcing element (180) forming an angle AT with the circumferential direction (X) of the tire (10), the active fibrous reinforcing elements (180) extending axially from one axial edge (18A, 18B) of the active layer (18) to the other axial edge (18A, 18B) of the active layer (18) substantially parallel to each other, the method for manufacturing the tire (10) comprising In this method, - A carcass assembly (52) intended to form at least one carcass layer (34) is disposed around a support (60) having a substantially cylindrical shape around a main axis (A), the carcass assembly (52) being axially delimited by two axial edges (52A, 52B) of the carcass assembly (52) and the carcass fibrous reinforcing elements (340) extending axially from one axial edge (52A, 52B) of the carcass assembly (52) to the other axial edge (52A, 52B) of the carcass assembly (52) substantially parallel to each other, each carcass fibrous reinforcing element (340) extending within the carcass assembly (52) along the main direction (K3) of each carcass fibrous reinforcing element (340) forming an initial angle A3 in the range of 80° to 90° in absolute value with respect to the circumferential direction (x) of the support (60), - An actuating assembly (50) intended to form the actuating layer (18) is arranged radially outside the carcass assembly (52), and the carcass assembly (52) and the actuating assembly (50) form an assembly (58) having a substantially cylindrical shape around the main axis (A) of the support (60), - The assembly (58) having a substantially cylindrical shape around the main axis (A) of the support (60) is deformed to obtain an assembly (58) having a substantially annular shape around the main axis (A) of the support (60), - The green form of the tire obtained from the assembly (58) having a substantially annular shape is crosslinked to obtain the tire (10), The method of manufacturing, The angle AT is in the range of 30° to 37° in absolute value, A method characterized by this.

2. The angle A3 is in the range of 85° to 90° in absolute value, The method according to claim 1.

3. The angle AT is in the range of 30° to 35° in absolute value, The method according to claim 1 or 2.

4. After the step of arranging the carcass assembly (52) and before the step of arranging the actuating assembly, using each bead (24) provided with a circumferential reinforcing element (26), - The two circumferential reinforcing elements (26) are arranged around the carcass assembly (52), - Each axial edge (52A, 52B) of the carcass assembly (52) is folded axially inward so that the carcass assembly (52) is wound axially around each circumferential reinforcing element (26), The method according to any one of claims 1 to 3.

5. When the said or each carcass layer (34) is axially delimited by two axial edges (34A, 34B) of the carcass layer (34) and comprises the carcass fibrous reinforcing element (340) extending axially from one axial edge (34A, 34B) of the carcass layer (34) to the other axial edge (34A, 34B), the main direction (D3) of each carcass fibrous reinforcing element (340) is the same as the circumferential direction (X) of the tire (10) and - An angle ACS which is strictly less than 80° in absolute value within the axial central portion (34S) of the carcass layer (34) extending axially side by side with the actuating layer (18) in the radial direction, - Each axial lateral portion (34F) of the carcass layer (34) extending axially between the axial center portion (34S) and each axial edge portion (34A, 34B) of the carcass layer (34), and within each such axial lateral portion (34F) wound around each circumferential reinforcing element (26), an angle ACF having an absolute value of from 80° to 90°, forming, The method according to claim 4.

6. The angle ACS has an absolute value in the range of 50° to 75°, The method according to claim 5.

7. Each axial lateral portion (34F) of the carcass layer (34) is - An inner axial lateral portion (38) axially disposed between the axial center portion (34S) and each circumferential reinforcing element (26), and the main direction (D3) of each carcass fibrous reinforcing element (340) forms an angle ACF1 with the circumferential direction (X) of the tire, - An outer axial lateral portion (40) axially disposed between each circumferential reinforcing element (26) and each axial edge portion (34A, 34B) of the carcass layer (34), and the main direction (D3) of each carcass fibrous reinforcing element (340) has an angle ACF2 opposite to the angle ACF1 such that |ACF1 - ACF2 - 180| ≦ 20°, preferably |ACF1 - ACF2 - 180| ≦ 10°, more preferably |ACF1 - ACF2 - 180| is substantially zero, and forms an angle with the circumferential direction (X) of the tire, The method according to claim 5 or 6.

8. The assembly (58) having a substantially cylindrical shape, after the deformation stage, the main direction (K3) of each carcass fibrous reinforcing element (340) is the same as the circumferential direction (x) of the support and - A final angle B3S having an absolute value of strictly less than 80° within the axial center portion (52S) of the carcass assembly (52) intended to extend axially radially aligned with the actuating assembly (50) and form the axial center portion (34S) of the carcass layer (34), - Two axial lateral portions (52F) of the carcass assembly (52) each extending axially between the axial center portion (52S) and each axial edge portion (52A, 52B) of the carcass assembly (52), and each intended to form each axial lateral portion (34F) of the carcass layer (34), and having a final angle B3F with an absolute value of from 80° to 90°, deformed to obtain the assembly (58) having a substantially annular shape so as to form The method according to any one of claims 5 to 7. **Claim 9** When the actuating assembly (50) is axially delimited by two axial edges (50A, 50B) of the actuating assembly (50) and the actuating fibrous reinforcing element (180) extends axially from one axial edge (50A, 50B) of the actuating assembly (50) to the other axial edge (50A, 50B) substantially parallel to each other, each actuating fibrous reinforcing element (180) forms an initial angle A2 in the range of 25° to 50° in absolute value with the circumferential direction (x) of the support (60) and extends within the actuating assembly (50) along the main direction (K2) of each actuating fibrous reinforcing element (180). The method according to any one of claims 1 to 8. **Claim 10** A tire (10) obtained by the method according to any one of claims 1 to 9.

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