Pneumatic

Abstract

The invention relates to a tire (100) comprising a crown (110), two sidewalls (120), and two bead sections (130). The crown comprises a working reinforcement (113) in which one or each working layer (114) comprises wire reinforcements forming an angle of 10° to 60° with a circumferential direction (Z). The tire comprises a carcass reinforcement (140) in which one or each carcass layer (141) comprises wire reinforcements which, with the circumferential direction, form an angle of 80° to 90° in each of two lateral portions (141F) and an angle of 30° to 80° in a crown portion.The working reinforcement and the carcass reinforcement have breaking strengths, expressed in daN / mm, which are at least equal to 11.5*Tx+18.7 and 1.8*Tx+16.0 respectively, where Tx is a dimensionless ratio equal to RT / RI, where RT and RI are radii measured between an axis of rotation (X100) and, respectively, the outermost radial end of the working reinforcement and the innermost radial end of the tire. See Figure 1 for abbreviations.

Description

Title of the invention: Pneumatics

[0001] The present invention relates to a pneumatic tire.

[0002] The invention relates in particular, but not exclusively, to tires for light vehicles, especially passenger vehicles, including four-wheeled and two-wheeled vehicles. The term "tire" refers to a tire designed to form a cavity by cooperating with a mounting support, commonly referred to as a "rim," this cavity being capable of being pressurized to a pressure greater than atmospheric pressure. The tire has a substantially toroidal shape of revolution around an axis of revolution of the tire, which coincides with an axis of rotation around which the tire can be driven to rotate in order to roll on the ground. This axis of revolution defines three directions, namely an axial direction, a circumferential direction, and a radial direction, conventionally used by those skilled in the art to describe the tire according to the following conventions:

[0003] - by axial direction, we mean the direction substantially parallel to the axis of tire revolution, that is to say the axis of rotation of the tire;

[0004] - by radial direction, we mean the direction along a radius of the tire, that is to say any direction intersecting the axis of rotation of the tire and substantially perpendicular to this axis;

[0005] - by circumferential direction, we mean the direction which is substantially perpendicular to both the axial direction and a radius of the tire; in other words, the circumferential direction is tangent to a circle whose center is on the axis of rotation of the tire; the circumferential direction is thus tangent to a rolling surface of the tire, intended to be in contact with the ground when the tire is rolling;

[0006] - by median plane of the tire, we mean the plane perpendicular to the axis of rotation of the tire, which passes through the axial middle of the tire's rolling surface;

[0007] - by meridian plane of the tire, we mean a plane containing the axis of rotation of the tire, the meridian plane thus being perpendicular to the circumferential direction;

[0008] - by radially internal, respectively radially external, we mean more close to the axis of rotation of the tire, respectively further from the axis of rotation of the tire;

[0009] - by axially internal, respectively axially external, we mean more close to the median plane of the tire, respectively further from the median plane of the tire; and

[0010] - by equatorial circumferential surface of the tire, we mean the surface cylindrical which is perpendicular to the radial direction and which passes through the equator of the tire, it being noted that the equator of the tire is, in a meridian plane, a geometric line which is parallel to the axis of rotation of the tire and located at an equidistance between the outermost radial point and the innermost radial point of the tire.

[0011] Typically, a tire comprises a crown extended radially inward on each side of the tire's median plane by first and second sidewalls, and then by first and second bead sections designed to contact the wheel rim. The crown, first and second sidewalls, and first and second bead sections define a toroidal inflation cavity for the tire. Here, a bead section is understood to be the radial portion of the tire designed to allow the tire to be attached to the rim. Thus, each bead section is specifically designed to be in contact with a rim hook, enabling it to be attached.The bead is thus delimited radially internally by the innermost radial end of the tire and radially externally by an axial line passing through the outermost radial point in contact with a standard rim as defined by the European Tyre and Rim Technical Organisation (ETRTO) standard, 2020. Furthermore, the sidewall is defined as the radial portion of the tire connecting the bead to the crown. The sidewall is delimited radially externally by a line perpendicular to the outer surface of the tire passing through the point where the angle between the tangent to the outer surface of the tire and a line parallel to the axial direction passing through that point is equal to 30°. When there are several points on a meridional cross-section where this angle is equal to 30°, the outermost radial point is selected.The sidewall is delimited radially internally by an axial line passing through the outermost radial point in contact with a standard rim as defined by the European Tyre and Rim Technical Organisation or "ETRTO" standard, 2020.

[0012] The crown comprises both a tread, intended to come into contact with the ground when the tire is rolling, and a crown reinforcement, which reinforces the crown and is arranged radially between the tread and a carcass reinforcement of the tire, connecting the two beads to each other by passing through the sidewalls and the crown.

[0013] During its use, the tire is likely to roll over foreign objects, which puncture its tread and may damage, even to the point of rupture, the crown reinforcement and / or the carcass reinforcement. In order to assess the tire's performance for this use case, it is known to apply a puncture test to the tire, typically the test called "breaking energy," which can be translated as "rupture energy test." This is a standardized test that measures the energy required for a standardized metal rod, called a "polar," to puncture the crown of the tire, in its mounted and inflated state, which is static and subjected to a standardized load. For example, in China, this "breaking energy" test is specified in section 4.5.1 of the GB9743-2024 standard; in the United States, this "breaking energy" test is specified in section S6.5 of the 49 CFR 571.139 standard. The energy measured at the moment of perforation of the tip by the polar is compared to a normalized minimum value: to satisfy the "breaking energy" test, this energy measured at the moment of perforation must be greater than the normalized minimum value, the latter being for example 588 J for the so-called "Extraload" category.

[0014] The invention relates more specifically to tires in the crown of which a triangulation is at least achieved between the wire reinforcements of a single carcass layer of the carcass reinforcement and the wire reinforcements of a single working layer of the crown reinforcement. Since the same layer of wire reinforcements is used to manufacture the carcass layer of various tire dimensions, and the same layer of wire reinforcements is used to manufacture the working layer of various tire dimensions, it is observed that the tire's sensitivity to the "breaking energy" test varies according to the tire dimensions: in other words, the tire may pass the "breaking energy" test for some of its dimensions, but not for other dimensions.Similar considerations apply to tires, whose carcass reinforcement consists of several carcass layers whose respective wire reinforcements are, at least in the apex, parallel to each other between the different carcass layers, and / or whose working reinforcement consists of several working layers whose respective wire reinforcements are parallel to each other between the different working layers.

[0015] The object of the present invention is to remedy this unsatisfactory situation, by proposing a solution which, while being specific to a tire of the type described in the immediately preceding paragraph, guarantees that the various dimensions of the tire will satisfy the "breaking energy" test or a similar perforation test.

[0016] To this end, the invention relates to a tire, comprising a crown, two sidewalls, each extending radially inwards from the crown, and two beads, which extend radially inwards from the two sidewalls respectively and which are adapted to hook the tire onto a nominal rim, the tire being in an inflated mounted state when it is mounted on the nominal rim inflated to a nominal pressure. The crown comprises both a tread, which is intended to come into contact with the ground when the tire is in motion, and a crown reinforcement, which is arranged radially within the tread. The crown reinforcement includes a working reinforcement consisting of a single working layer or several working layers that are radially superimposed, the working layer or layers (i) being axially delimited by two axial edges of the working layer, and (ii) comprising wire reinforcements that extend from one to the other of the two axial edges of the working layer in a substantially parallel manner along a principal direction DT that forms an angle AT with a circumferential direction of the tire, the angle AT having an absolute value of 10° to 60°. In the case where the working reinforcement consists of several working layers,The AT angles respectively associated with the working layers are identical to each other. The tire comprises a carcass reinforcement, which is arranged radially inside the crown reinforcement and which consists of a single layer of carcass or of several layers of carcass which are radially superimposed in the crown, the layer or layers of carcass (i) being anchored in each bead and extending from one bead to the other through each sidewall and the crown, (ii) being axially delimited by two axial edges of the carcass layer, and (iii) comprising wire reinforcements which extend from one to the other of the two axial edges of the carcass layer in a principal direction DC, which, in each of two lateral portions of the carcass layer, arranged respectively in the sidewalls, forms an angle ACF with the circumferential direction of the tire, the angle ACF having, in absolute value, a value of 80° to 90°, and which,In a top portion of the carcass layer, extending axially in line with the radial axis of the working reinforcement, an angle ACS forms with the circumferential direction of the tire. The absolute value of the ACS angle is between 30° and 80°, and it has an orientation opposite to that of the AT angle(s). The wire reinforcements of the carcass layer are substantially parallel to each other in the top portion of the carcass layer. If the carcass reinforcement consists of several carcass layers, the ACS angles associated with each carcass layer are identical. The working reinforcement has a breaking strength, expressed in daN / mm, which is at least equal to 1.5*Tx+18.7 and the carcass reinforcement has a breaking strength, expressed in daN / mm, which is at least equal to 1.8*Tx+16.0, where Tx is a dimensionless rate which is equal to RT / RI where RT and RI are measured radii, in the mounted inflated state of the tire,radially between an axis of rotation of the tire and, respectively, the outermost radial end of the working frame and the innermost radial end of the tire.

[0017] One of the ideas behind the invention is to define a dimensioning rule both for the working reinforcement with a single working layer or with several working layers and for the carcass reinforcement with a single carcass layer or with several carcass layers, so that the tire satisfies a puncture test, in particular the "breaking energy" test, for all its dimensions, including for its dimensions most sensitive to this test.Indeed, the inventors established that, for a given tire—that is, for a tire whose various possible dimensions are manufactured from the same given layer of wire reinforcement for its carcass layer(s) and from the same given layer of wire reinforcement for its working layer(s)—the change in dimensions affects the density of the wire reinforcement in the working layer(s) and the density of the wire reinforcement in the upper portion of the carcass layer(s), but also the mechanical behavior of these layers during the puncture test. Without being bound by any particular theory, the inventors sought to quantify a relationship between the tire's sensitivity to the "breaking energy" test and the various tire dimensions.

[0018] In practice, the variation in the dimensions of the tire is quantifiable by a rate, denoted Tx in this document, which is dimensionless and which is strictly greater than one.This Tx rate is mathematically linked to the conformation rate of the tire when the latter is manufactured by conformation, that is to say by controlled inflation, of, jointly, the layer(s) of wire reinforcement which, once formed, respectively form the working layer(s), and the layer(s) of wire reinforcement which, once formed, respectively form the carcass layer(s): the conformation rate is then equal to the ratio of dimensional increase between the outside diameter, or the outside radius, of a cylindrical support, around which these different layers of wire reinforcement are wound flat, and the maximum inside diameter, or the maximum inside radius, of the substantially toroidal shape of the tire, in which these layers of wire reinforcement are deformed by inflation to obtain the tire.Since the invention is applicable regardless of how the tire is manufactured, including both controlled inflation (as explained above) and molding over an internal core, the Tx ratio is more generally defined as RT / RI, where RT and RI are radii measured radially between a tire's axis of rotation and, respectively, the outermost radial end of the working structure and the innermost radial end of the tire, in the mounted and inflated state. The "mounted and inflated state" of the tire refers to the state of the tire when it is both mounted on a nominal rim and inflated. to a nominal pressure, as defined by the European Tyre and Rim Technical Organisation (ETRTO) standard. The ETRTO standard associates each tire size or dimension with a nominal rim, on which the tire can be mounted. The rim's dimensions are adjusted to match those of the tire in the contact area between the rim and the tire. Similarly, the ETRTO standard defines, based on factors including the tire type and / or size, a nominal pressure at which the tire, mounted on its corresponding nominal rim, is inflated. This pressure is determined for predetermined environmental and load conditions.

[0019] The inventors have established, in particular through calculations and experiments, that the "breaking energy" test or, more generally, a similar puncture test is satisfied by the tire according to the invention provided that (i) the working reinforcement has a breaking strength, expressed in daN / mm, which is at least equal to 1.5*Tx+18.7 and (ii) the carcass reinforcement has a breaking strength, expressed in daN / mm, which is at least equal to 1.8*Tx+16.0. Thanks to this dimensioning rule, it is guaranteed that at least one of the layers among the working layer(s) and the carcass layer(s) sufficiently resists the polar during the puncture test, in particular during the "breaking energy" test, to satisfy this test.

[0020] It should be noted that the breaking forces considered above for the working reinforcement and the carcass reinforcement, respectively, are the breaking forces of these reinforcements in their conformed state within the finished tire, and not the breaking forces of flat plies from which the working and carcass layers are obtained during tire manufacturing. In practice, each of these breaking forces for the working reinforcement and the carcass reinforcement, respectively, is a quantity that can be calculated from measurements taken directly on a given tire.To do this, the wire reinforcements of each of the working and carcass layers are first extracted without degumming from the tire, then each of all or part of the wire reinforcements thus extracted is subjected to either the measurement standard ASTM D885 / D885M-10a when the wire reinforcement in question is textile or essentially textile, or the measurement standard ASTM D2969-00 when the wire reinforcement in question is metallic or essentially metallic: in particular, the wire reinforcement is subjected to tensile stress by an ad hoc machine equipped with clamps between which the wire reinforcement in question is extended until a break must be obtained outside the respective gripping zones of the clamps, it being noted that the tensile force applied to the wire reinforcement by the machine is measured during the test to have a force, called unit breaking force, corresponding to the force at which the wire reinforcement breaks.The breaking strength of the layer from which the considered wire reinforcement was extracted is calculated by multiplying the unit breaking strength by the average axial density of wire reinforcement(s) in that layer, noting that the . The average axial density of wire reinforcement is equal to the average number of wire reinforcements per millimeter of the axial width of the layer in question, or per millimeter of the layer measured along the axial direction of the tire. This explains why the breaking strength is expressed in Newtons (or multiples of Newtons) per millimeter. In practice, the axial density of wire reinforcement is determined on an axial portion of the layer, which is axially centered on the median plane of the tire and corresponds to half the axial width of the tire.In the case where the working reinforcement and / or carcass consists of a single layer of working reinforcement and / or carcass, the breaking strength of the working reinforcement and / or carcass is equal to the breaking strength of that layer of working reinforcement and / or carcass; in the case where the working reinforcement and / or carcass consists of several layers of working reinforcement and / or carcass, the breaking strength of the working reinforcement and / or carcass is equal to the sum of the respective breaking forces of the layers of working reinforcement and / or carcass.

[0021] The "principal direction" along which a wire reinforcement extends is understood to mean the direction along which the wire reinforcement extends along its greatest length. This principal direction may be straight or curved, the reinforcement element being able to describe a straight or curved path along its principal direction.

[0022] By "portion of a layer, extending axially in the radial line of a reference object", we mean a portion of this layer, contained between the radial projections of the axial edges of this layer on the reference object.

[0023] Any interval of values ​​designated by the expression "between a and b" represents a domain of values ​​going from more than a to less than b, that is to say excluding the bounds a and b from this domain. Any interval of values ​​designated by the expression "from a to b" means a domain of values ​​going from a to b, that is to say including the bounds a and b in this domain.

[0024] In the tire, a considered angle is the smaller of the two angles defined between the reference line, here the circumferential direction of the tire, and the principal direction along which the wire reinforcement in question extends. Furthermore, the orientation of an angle refers to the direction, clockwise or counterclockwise, in which one must turn from the reference line, here the circumferential direction of the tire, defining the angle to reach the principal direction along which the wire reinforcement in question extends.

[0025] In practice, the tire according to the invention is preferably intended for passenger vehicles. In particular, within the meaning of the European Tyre and Rim Technical Organisation or "ETRTO" standard, the tire has, in a meridional cross-sectional plane, a section characterized by a section width S, measured along the axial direction, and by a section height H, measured along The radial direction, such that the H / S ratio, expressed as a percentage, is at most 90, preferably at most 80, and more preferably at most 70, and is at least 25, preferably at least 40, and the section width S is at least 115 mm, preferably at least 155 mm, and more preferably at least 175 mm, and at most 385 mm, preferably at most 315 mm, more preferably at most 285 mm, and even more preferably at most 255 mm. Furthermore, the nominal rim diameter associated with the tire according to the invention is at least 12 inches, preferably at least 16 inches, and at most 24 inches.

[0026] According to advantageous optional features of the tire according to the invention, taken individually or in all technically possible combinations:

[0027] - the working reinforcement has a breaking strength, expressed in daN / mm, which is at least equal to 12.9*Tx+21.7;

[0028] - the carcass reinforcement has a breaking strength, expressed in daN / mm, which is at least equal to l.8*Tx+18.5;

[0029] - the Tx rate is between 1.2 and 1.9;

[0030] - angle AT has an absolute value of 15° to 45° and angle ACS has an absolute value of absolute, from 35° to 70°;

[0031] - the carcass reinforcement consists of the single layer of carcass and the reinforcement the working layer consists of the single working layer;

[0032] - each of the wire reinforcements of the or each working layer is a monofilament metallic having a diameter which is equal to or greater than 0.33 mm, preferably less than 0.50 mm;

[0033] - the top reinforcement further comprises a shrink-fit layer, which (i) is arranged radially between the tread and the working reinforcement, (ii) is axially delimited by two axial edges of the shrink layer, and (iii) includes at least one wire reinforcement which is circumferentially wound in a helix along a principal direction DF from one to the other of the two axial edges of the shrink layer, which principal direction DF forms an angle AF with the circumferential direction of the tire, the angle AF being, in absolute value, at most 10°.

[0034] According to an advantageous optional aspect of the tire according to the invention, the shrink-fit layer consists of a strip which (i) is circumferentially wound in a helix over several turns, and (ii) is non-overlapping radially on itself in each of two axially external portions of the shrink-fit layer, which extend axially inwards from respectively one and the other of the two axial edges of the shrink-fit layer and which each have an axial width which is equal to at least 12.5% ​​of the axial width of the or each working layer.

[0035] Thanks to this feature, in each of the two axially external portions of the or each layer of the reinforcement, as defined above, this reinforcement layer extends axially without overlapping of its constituent strip at the shoulders of the tread, that is to say, at the axially opposed end portions of the tread from which the sidewalls of the tire extend radially inwards. Without this feature, such overlapping of a reinforcement strip at the shoulders, which is usually considered to counteract centrifugal forces in the shoulders and thus to increase the performance of the tire at high rolling speeds, would make the stiffness distribution of the crown reinforcement axially inhomogeneous in the corresponding axial portion of the crown.By ensuring that the strip is wound in a non-overlapping manner on itself, in other words by not overlapping the windings of this strip, in each of the two axially external portions of the shrink layer, the aforementioned aspect avoids any "over-shrinking" of the shrink reinforcement at the shoulders, which homogenizes the rigidity of the apex reinforcement along the axial direction of the tire at the shoulders and which helps to limit the risk of premature wear of the shoulders.In practice, the implementation of the aforementioned aspect, in that it prohibits any radial overlap between the turns of the strip in each of the two axially external portions of the shrink-wrapping layer, can be achieved either by winding these turns contiguously over the entire axial width of the two axially external portions of the shrink-wrapping layer, by means of winding the strip with a suitable constant pitch, or by winding these turns non-contiguously, that is to say with transverse free spaces between the turns of the strip, by means of winding the strip with an increasing pitch.

[0036] Taking into account the explanations given so far, it will be understood that it is possible to implement the above aspect within a tire having all the characteristics of the invention defined above, except for the characteristics relating to the dimensioning in breaking strength of its carcass and working reinforcements.

[0037] According to additional advantageous features relating to the aforementioned aspect, the strip includes, on each axial side of a median plane of the tire, a most axially external point which is axially further from the median plane than the corresponding axial edge of the or each working layer.

[0038] The invention will be better understood upon reading the following description, given solely by way of example and with reference to the drawings in which:

[0039] - [Fig. 1] [Fig. 1] is a partial schematic section of a conforming tire to the invention, this section being in a cutting plane corresponding to a meridian plane of the tire;

[0040] - [Fig.2] [Fig.2] is a partial schematic elevation view along arrow II of the [Fig.l], showing the tire partially torn away to reveal wire reinforcements;

[0041] - [Fig.3] [Fig.3] is a partial schematic elevation view along arrow III of [Fig. 1], showing wire reinforcements of the tire carcass; and

[0042] - [Fig.4] [Fig.4] is a view similar to [Fig.2], showing partial tear-off layers of a tire crown reinforcement.

[0043] Figures 1 to 4 show a tire 100 and a geometric coordinate system whose X, Y, and Z directions correspond respectively to the axial, radial, and circumferential directions of the tire 100, as defined in the introductory section of this document. The tire 100 has a substantially toroidal shape around an axis of revolution, which is substantially parallel to the axial direction X and coincides with an axis of rotation XI00 of the tire 100, around which the latter can be driven in rotation to roll on the ground. The tire 100 is, for example, intended for a passenger vehicle.

[0044] In [Fig.1], the tire 100 is associated with a nominal rim 10, in the sense of the standard of the European Tyre and Rim Technical Organisation or “ETRTO”, on which the tire 100 can be mounted, as schematically illustrated in dotted lines.

[0045] As shown in Figures 1 and 2, the tire 100 comprises a crown 110 having a tread 111, which extends in the circumferential direction Z over the entire circumference of the tire 100 and which is intended to come into contact with the ground when rolling the tire 100. The crown 110 also comprises a crown reinforcement 112 which extends in the crown 110 in the circumferential direction Z over the entire circumference of the tire 100, being radially surmounted by the tread 111.

[0046] The top reinforcement 112 includes a working reinforcement 113 consisting of at least one working layer 114. Here, a single working layer 114 is advantageously provided, so that the working reinforcement 113 consists of this single working layer 114. The working reinforcement 113 is then, with the exception of the single working layer 114, devoid of any layer reinforced by wire reinforcement elements. The working reinforcement 113, and consequently the top reinforcement 112, is thus lightened. In what follows, for the sake of simplicity, we will refer to the working layer 114 without repeatedly stating that this layer is unique.

[0047] The working layer 114 is axially delimited by two axial edges 114A and 114B of the working layer 114. The working layer thus has an axial width LT which is equal to the axial distance between the axial edges 114A and 114B. The axial edges 114A and 114B of the working layer 114 are arranged axially on either side of a median plane M of the tire 100, this median plane M being as defined in the introductory part of this document. The working layer 114 includes wire reinforcements 114R which, in practice, are embedded in an elastomeric matrix of the working layer 114. The wire reinforcements 114R extend from one to the other of the axial edges 114A and 114B in a substantially parallel manner along a principal direction DT of the wire reinforcements 114R. This principal direction DT forms, with the circumferential direction Z of the tire 100, an angle AT.The angle AT has an absolute value ranging from 10° to 60°, preferably from 15° to 45°. As an example, the angle AT is equal to -24°.

[0048] The structural and dimensional specifications of the 114R wire reinforcements are not limiting to the invention. Thus, each 114R wire reinforcement can be made of metal and / or textile, optionally at least partially made of recycled or renewable material. Preferably, each 114R wire reinforcement is made essentially, or even exclusively, of metal. In particular, especially for reasons of compactness, each 114R wire reinforcement is advantageously a metallic monofilament having a diameter equal to or greater than 0.33 mm, preferably less than 0.50 mm.

[0049] In the embodiment considered here, the top reinforcement 112 also includes a shrink-fit reinforcement 115, comprising at least one shrink-fit layer 116. Here, the shrink-fit reinforcement 115 advantageously comprises a single shrink-fit layer 116 and is made up of this single shrink-fit layer 116. The shrink-fit reinforcement 115 is then, with the exception of the single shrink-fit layer 116, devoid of any layer reinforced by wire reinforcement elements. The shrink-fit reinforcement 115, and consequently the top reinforcement 112, is thus made lighter. In what follows, for the sake of simplicity, we will refer to the shrink-fit layer 116 without repeatedly stating that this layer is unique.

[0050] The shrink-fit reinforcement 115, here the shrink-fit layer 116, is arranged radially outside the working reinforcement 113 and is therefore radially intercalated between the working reinforcement 113 and the tread 111. In the embodiment considered here, the shrink-fit reinforcement 115, here the shrink-fit layer 116, has an overall axial width which is greater than the axial width LT of the working reinforcement 113, here of the working layer 114; in an alternative not shown, it is otherwise.

[0051] The shrink-fit layer 116 is axially delimited by two axial edges 116A and 116B of the shrink-fit layer 116, which are arranged axially on either side of the median plane M of the tire 100. Here, as illustrated in Figures 1 and 2, the axial edges 116A and 116B of the shrink-fit layer 116 extend axially outwards respectively from the axial edges 114A and 114B of the working layer; in an alternative not shown, it is otherwise.

[0052] The shrink-fit layer 116 comprises a single wire reinforcement or, as in this case, several wire reinforcements 116R, each of which is circumferentially wound in a helix along a principal direction DF of the wire reinforcement concerned, from one to the other of the axial edges 116A and 116B. The principal direction DF forms, with the circumferential direction Z of the tire 10, an angle AF which has, in absolute value, at most 10°, preferably at most 7°, more preferably at most 5°. By way of example, the angle AF is equal to -5°.

[0053] In the broadest definition of the invention, the structural and dimensional specifications of the wire reinforcement(s) 116R are not limiting. By way of example, the wire reinforcement(s) 116R are formed by a cable as described in WO2016166056, WO2016166057, WO2019122620, W02016091809, W02016091810, W02016091811, W02016091812 or WO2021074511, this cable being, where appropriate, at least partly made of recycled or renewable material.

[0054] In the embodiment considered here, as more specifically illustrated in [Fig. 4], the shrink-fit layer 116 advantageously consists of a strip 117 which is circumferentially wound, advantageously continuously, in a helix over several turns. The strip 117 is thus wound radially non-overlappingly upon itself, here advantageously in a substantially contiguous manner between the turns of the strip 117, in at least each of two axially external portions 116E of the shrink-fit layer 116, which extend axially inwards from respectively one and the other of the two axial edges 116A and 116B of the shrink-fit layer. Each of the two axially external portions 116E of the shrinkage layer 116 has an axial width LFE which is equal to at least 12.5% ​​of the axial width LT of the working layer 114.Thus, the turns of the band 117 do not radially overlap each other at the level of each of the two shoulders of the tread 111. In the rest of the shrink layer 116, that is to say in a portion of the shrink layer 116, which extends axially from one to the other of its two axially external portions 116E and which is axially centered on the median plane M of the tire 100, the turns of the band 117 are advantageously, but not necessarily, radially non-overlapping each other, whether contiguous or not.

[0055] The first and last turns of the strip 117 form, on their axial side facing away from the median plane M, respectively the axial edges 116A and 116B of the shrink-wrapping layer 116, or vice versa. The strip 117 extends circumferentially in length from one to the other of two circumferential edges 117C and 117D of the strip 117, which correspond respectively to longitudinal ends of the strip through which the winding of the strip 117 begins and ends, or vice versa.Perpendicular to a longitudinal direction of the strip 117, along which the latter extends circumferentially from one to the other of its circumferential edges 117C and 117D, the strip has a width L117, which is substantially constant along the length of the strip 117 and which is less than half, preferably a quarter, more preferably a tenth, of the axial width of the working reinforcement 113, here of the working layer 114. By way of non-limiting example, the width L117 of the strip 117 is equal to a value ranging from 5.0 to 15.0 mm, for example equal to 10.0 mm.

[0056] In practice, as schematically illustrated in [Fig. 4], the wire reinforcements 116R are integrated into the strip 117 so that their principal direction DF corresponds substantially to the longitudinal direction of the strip 117. The wire reinforcements 116R are, for example, embedded in an elastomeric matrix of this strip and are distributed regularly over the width of the strip 117. By way of non-limiting example, two to ten wire reinforcements 116R are thus integrated into the strip 117.

[0057] In all cases, the strip 117 includes two outermost axial points PI 17.1 and PI 17.2 which are arranged axially on either side of the median plane M of the tire 100. Here, the outermost axial point PI 17.1 is formed at the intersection of the axial edge 116A and the circumferential edge 117C while the outermost axial point PI 17.2 is formed at the intersection of the axial edge 116B and the circumferential edge 117D. The axial distance separating the outermost axial points PI 17.1 and PI 17.2 corresponds to the overall axial width of the shrinkage layer 116, which, as indicated above, is here greater than the axial width LT of the working layer 114. More precisely, as illustrated in [Fig.4], on one of the two axial sides of the median plane M, the outermost axial point PI 17.1 is advantageously axially further from this median plane M than the axial edge 114A of the working layer 114 while, on the other of the two axial sides of the median plane M, the outermost axial point PI 17.2 is advantageously axially further from this median plane M than the axial edge 114B of the working layer 114. This arrangement is of interest in terms of stiffness for the top reinforcement 112 under certain conditions of use of the tire 100, in particular at high rolling speeds.

[0058] The tire 100 further comprises two sidewalls 120, each extending radially inwards from the apex 110 and arranged axially on either side of a median plane M of the tire 100, this median plane being as defined in the introductory part of this document. Only one of these two sidewalls 120 is visible in [Fig. 1].

[0059] The tire 100 also has two beads 130, which extend radially inwards respectively from the two sidewalls 120. Only one of these two beads 130 is visible in [Fig. 1]. Thus, one of the sidewalls 120 connects one of the two beads 130 to the apex 110 and the other sidewall 120 connects the other bead 130 to the apex 110, the two beads 130 being opposite each other with respect to the median plane M.

[0060] Each of the two bead 130 is provided with a circumferential reinforcing element 131, which extends into the corresponding bead in the circumferential direction Z and which is, for example, a bead. The circumferential reinforcing elements 131 allow the tire 100 to be attached to the nominal rim 10. Each circumferential reinforcing element 131 is advantageously radially surmounted by a mass of rubber packing 132 of the corresponding bead 130.

[0061] The tire 100 further includes a carcass reinforcement 140 which is anchored in each bead 130 and extends from one bead to the other through each sidewall 120 and the top 110. In the top 110, the carcass reinforcement 140 is arranged radially inside the top reinforcement 112, more precisely the working reinforcement 113 of the latter.

[0062] The frame reinforcement 140 consists of at least one layer of frame 141. Here, a single layer of frame 141 is advantageously provided, so that the frame reinforcement 140 consists of the single layer of frame 141. The frame reinforcement 140 is then, with the exception of the single layer of frame 141, devoid of any layer reinforced by wire reinforcement elements. The frame reinforcement 140 is thus made lighter. In what follows, for the sake of simplicity, we will refer to the single layer of frame 141 without repeatedly stating that this layer is unique.

[0063] The carcass layer 141 is anchored in each of the two ridges 130 and extends from one to the other of these ridges 130 through each of the two flanks 120 and through the top 110. Here, as clearly visible in [Fig. 1], the carcass layer 141 comprises two wound portions 141T which are respectively wound around the circumferential reinforcing members 131 so that, in each ridge 130, the carcass layer 141 forms an axially inner portion 1411 and an axially outer portion 141E, which extend from the wound portion 141T axially on either side of the corresponding circumferential reinforcing member 131. In For each bead 130, the mass of packing rubber 132 is intercalated between the axially inner portion 1411 and the axially outer portion 141E. Other anchoring methods for the carcass layer 141 are possible, for example as described in US5702548.

[0064] The carcass layer 141 is axially delimited by two axial edges 141A and 14IB of the carcass layer 141, it being noted that only the axial edge 141A is visible in the figures, more precisely in [Fig. 1], and that the axial edge 141B is substantially symmetric to the axial edge 141A with respect to the median plane M. The carcass layer 141 includes wire reinforcements 141R which, in practice, are embedded in an elastomeric matrix of the carcass layer 141. The wire reinforcements 141R extend from one to the other of the axial edges 141A and 141B along a principal direction DC of the wire reinforcements 141R.

[0065] As illustrated in Figures 1 and 3, in each of two lateral portions 141F of the carcass layer 141, which are arranged respectively in the sidewalls 120, the principal direction DC of each of the wire reinforcements 141R forms, with the circumferential direction Z of the tire 100, an angle ACF which has, in absolute value, a value of 80° to 90°. By way of example, the angle ACF associated with each of the wire reinforcements 141R is equal to 90°.

[0066] In practice, each lateral portion 141F of the carcass layer 141 has a radial height equal to at least 5%, preferably at least 15% and more preferably at least 30% of the section height H of the tire 100 and equal to at most 80%, preferably at most 70% and more preferably at most 60% of the radial height H of the tire 100. By way of example, the radial height of each lateral portion 141F is equal to 40% of the section height H of the tire 100. The equatorial circumferential surface of the tire 10, as defined above and denoted E in Figures 1 and 3, intersects each lateral portion 141F of the carcass layer 141.

[0067] As illustrated in [Fig. 2], in a top portion 141S of the carcass layer 141, extending axially radially above the working layer 114, the wire reinforcements 141R of the carcass layer 141 are parallel to each other and their principal direction DC forms an angle ACS with the circumferential direction Z of the tire 100. The angle ACS has an absolute value of 30° to 80°, preferably 30° to 79°, and even more preferably 35° to 70°. By way of example, the angle ACS is equal to +43°.

[0068] In practice, the upper portion 141S of the carcass layer 141 has an axial width that is equal to at least 40%, preferably at least 50%, of the axial width of the working layer 114 and equal to at most 90%, preferably at most 80%, of the axial width of the working layer 114. By way of example, the width The axial width of the top portion 141S is equal to 60% of the axial width of the working layer 114. The median plane M of the tire 100 intersects this top portion 141S. More preferably, the top portion 141S is axially centered on the median plane M of the tire 10.

[0069] As illustrated in [Fig.2], in a portion of the vertex 110, which, in projection along the radial direction, corresponds to the summit portion 141S of the carcass layer 141, the angles AT, AF and ACS are in pairs different in absolute value and the angles AT and ACS have respective orientations which are opposite to each other.

[0070] The structural and dimensional specifications of the 141R wire reinforcements are not limiting to the invention. Thus, each 141R wire reinforcement can be made of metal and / or textile, optionally at least partially made of recycled or renewable material. Preferably, each 141R wire reinforcement is made essentially, or even exclusively, of textile.

[0071] The apex 110, the two sidewalls 120, and the two bead 130 jointly define a toroidal cavity 150 of the tire 100, delimited by an internal surface 151 of the tire 100. This toroidal cavity 150 allows the tire 100 to be inflated when the latter is mounted on the nominal rim 10. When the tire 100 is mounted on the nominal rim 10, the toroidal cavity 150 is closed jointly by the tire 100 and the nominal rim 10, so that it can be pressurized by an inflation gas, which is introduced into the toroidal cavity 150 and with which the internal surface 151 is then in contact. In the embodiment considered here, the internal surface 151 is supported by a sealing layer 152 that is substantially impermeable to the inflation gas. For this purpose, this sealing layer 152 includes a sealing composition including, for example, one or more butyl rubbers, such as that described in WO2016 / 001226.As mentioned above, the tire 100 is in a mounted inflated state when it is both mounted on the nominal rim 10 and inflated to a nominal pressure, as defined by the European Tyre and Rim Technical Organisation or "ETRTO" standard.

[0072] In its mounted and inflated state, the tire 100 exhibits:

[0073] - a radius RT which, as shown in [Fig. 1], is measured radially between the axis of rotation XI00 of the tire and a most radially outer end of the working layer 114, this end corresponding, in practice, to the most radially outer point of the radially outer face of the working layer 114 and belonging, here, to the median plane M of the tire, and

[0074] - a radius RI which, as also shown in [Fig. 1], is measured radially between the X100 axis of rotation of the tire and the innermost radial end of the tire 100.

[0075] The RT / RI ratio is equal to a dimensionless ratio, hereafter referred to as Tx, which, by definition, is strictly greater than 1. As indicated above, this Tx ratio reflects the conformation ratio of the tire 100 when the latter is manufactured by controlled inflation. Regardless of how the tire 100 is manufactured, it is understood that the Tx ratio varies according to the size of the tire 100. By way of non-limiting examples, the Tx ratio is equal to 1.45 when the size of the tire 100 is 245 / 45 / 18, to 1.50 when the size of the tire 100 is 235 / 55 / 19, and to 1.61 when the size of the tire 100 is 215 / 65 / 17. Preferably, the Tx ratio is between 1.2 and 1.9.

[0076] The working layer 114 and the carcass layer 141 are designed such that:

[0077] - the working layer 114 has a breaking strength, expressed in daN / mm², such that measurable by the ad hoc measurement experiment mentioned above, which is at least equal to 11.5*Tx+18.7, preferably at least equal to 12.9*Tx+21.7, and

[0078] - the carcass layer 141 has a breaking strength, expressed in daN / mm², such that measurable by the ad hoc measurement experiment mentioned above, which is at least equal to 1.8*Tx+16.0, preferably at least equal to 1.8*Tx+18.5.

[0079] In this way, as explained above, the tire 100 is guaranteed to pass a puncture test, in particular the “breaking energy” test.

[0080] In practice, ensuring that the working layers 114 and carcass layers 141 exhibit breaking strength values ​​that satisfy the limit values ​​calculated by the formulas above relies essentially on the specific characteristics of these working layers 114 and carcass layers 141, in particular their wire reinforcements 114R and 141R with regard to their individual structure / nature, their individual dimensions, and their spacing / pitch between them. Those skilled in the art can adapt these characteristics accordingly. By way of non-limiting examples:

[0081] - the working layer 114 is obtained by shaping a working sheet of which Wire reinforcements, which form the 114R wire reinforcements after shaping the working sheet, are metallic cables that:

[0082] - are each made up of an assembly of two 0.30 mm metal wires diameter each, the cables being axially spaced in pairs with an inter-cable pitch of 0.90 mm before shaping the working tablecloth, or

[0083] - are each made of a metallic monofilament 0.38 mm in diameter, the cables being axially spaced in pairs with an inter-cable pitch of 0.68 mm before shaping the working sheet; and

[0084] - the carcass layer 141 is obtained by shaping a carcass sheet including wire reinforcements, which form the 141R wire reinforcements after shaping of the carcass ply, are PET (polyethylene terephthalate) yarns of grade 334 / 2, the carcass layer having an axial density of wire reinforcements equal to 80 wires / dm before shaping of the carcass layer.

[0085] The invention has been studied more particularly for three tire sizes, for which tire 100 has been compared to tires not conforming to the invention. The table below shows, for each of the six tires considered and respectively referenced PI to P6, its size, its Tx rate, minimum values ​​of breaking force as calculated by the formulas indicated, breaking force measurements as obtained by the ad hoc measurement experiment mentioned above, and a measurement of the energy applied, during the "breaking energy" test, to a polar at the moment of perforation of the tire's crown by this polar: Dimension Tx l,8*Tx +16.0 ll,5*Tx +18.7 Tensile strength measurement for the carcass layer (daN / mm) Tensile strength measurement for the working layer (daN / mm) Puncture energy during the "breaking energy" test (J) PI 215 / 65 / 17 1.61 18.9 37.2 30.1 44.1 614 P2 215 / 65 / 17 1.61 18.9 37.2 30.1 33.7 405 P3 215 / 65 / 17 1.61 18.9 37.2 17.1 44.1 428 P4 235 / 55 / 19 1.50 18.7 36.0 27.0 48.4 995 P5 235 / 55 / 19 1.50 18.7 36.0 27.0 28.7 357 P6 245 / 45 / 18 1.45 18.6 35.4 26.7 50.3 718

[0086] Tires PI, P4, and P6 are examples of tire 100, and their puncture energy exceeds the minimum standardized value mentioned above for the "breaking energy" test, namely 588 J in the "Extraload" category. Conversely, tires P2, P3, and P5 do not conform to the invention, in that:

[0087] - for the P2 tire, the breaking strength of its working layer is less than the minimum value as calculated by the formula 1 l.5*Tx +18.7, which means that its perforation energy is below the aforementioned standardized minimum value,

[0088] - for the P3 tire, the breaking strength of its carcass layer is less than the minimum value as calculated by the formula l.8*Tx + 16.0, which means that its perforation energy is below the aforementioned normalized minimum value, and

[0089] - for the P5 tire, the breaking strength of its working layer is less than the minimum value as calculated by the formula 1 l,5*Tx +18.7, which means that its perforation energy is below the aforementioned normalized minimum value.

[0090] The P2 tire differs from the PI tire in that, unlike the working layer 114 of the PI tire, obtained by shaping a working layer whose wire reinforcements are cables which are each made up of an assembly of four metal wires of 0.26 mm diameter each and which are spaced apart by an inter-cable pitch of 1.25 mm before shaping the working layer and of 1.36 mm after shaping this layer, the working layer of the P2 tire is obtained by shaping a working layer whose wire reinforcements are cables which are each made up of an assembly of two metal wires of 0.30 mm diameter each and which are spaced apart by an inter-cable pitch of 1.20 mm before shaping the working layer and of 1.31 mm after shaping this layer.

[0091] The P3 tire differs from the PI tire in that, unlike the carcass layer 141 of the PI tire, obtained by shaping a carcass ply whose wire reinforcements are PET yarns of count 334 / 2 and whose axial density in the carcass ply is equal to 80 yarns / dm before shaping the carcass ply and to 73 yarns / dm after shaping this ply, the carcass layer of the P3 tire is obtained by shaping a carcass ply whose wire reinforcements are PET yarns of count 144 / 2 and whose axial density in the carcass ply is equal to 104 yarns / dm before shaping the carcass ply and to 95 yarns / dm after shaping this ply.

[0092] The P5 tire differs from the P4 tire in that, unlike the working layer 114 of the P4 tire, obtained by shaping a working layer whose wire reinforcements are monofilamentary metal cables of 0.38 mm diameter each and spaced with an inter-cable pitch of 0.68 mm before shaping the working layer and of 0.83 mm after shaping this layer, the working layer of the P5 tire is obtained by shaping a working layer whose wire reinforcements are monofilamentary metal cables of 0.32 mm diameter each and spaced with an inter-cable pitch of 0.70 mm before shaping the working layer and of 0.85 mm after shaping this layer.

[0093] The invention is not limited to the embodiments described so far.

[0094] Thus, as an unshown variant of the tire 100, its working structure 113 does not consist of the single working layer 114, but consists of several, in particular two, working layers, which are radially superimposed. These radially superimposed working layers are each similar to the layer of The working layer 114 and the working layer 100 are thus respectively associated with identical AT angles. The calculation formula indicated above for the working layer 114 of the tire 100 then applies jointly to the radially superimposed working layers, in other words, to the working reinforcement formed by these radially superimposed working layers. The Tx ratio remains defined as equal to RT / RI, where RT is measured with respect to the outermost radially outermost end of the outermost radially superimposed working layer, in other words, with respect to the outermost radially outermost end of the working reinforcement formed by these radially superimposed working layers.

[0095] Also as a variant of the tire 100, not shown and combinable with the variant described above, the carcass reinforcement 140 is not made up of the single carcass layer 141, but consists of several, in particular two, carcass layers, which are radially superimposed in the crown of the tire. These radially superimposed carcass layers are each similar to the carcass layer 141 and are thus respectively associated with identical ACS angles. The calculation formula indicated above for the carcass layer 141 of the tire 100 then applies jointly to the radially superimposed carcass layers, in other words, to the carcass reinforcement made up of these radially superimposed carcass layers.

Claims

1. Claims A tire (100), comprising a crown (110), two sidewalls (120), each of which extends the crown radially inward, and two beads (130), which extend the two sidewalls radially inward respectively and which are adapted to attach the tire to a nominal rim (10), the tire being in an inflated mounted state when it is both mounted on the nominal rim and inflated to a nominal pressure, wherein the crown (110) comprises both a tread (111), which is intended to come into contact with the ground when the tire is rolling, and a crown reinforcement (112), which is arranged radially inside the tread, wherein the crown reinforcement (112) comprises a working reinforcement (113) consisting of a single working layer (114) or of several working layers which are radially superimposed, the or each working layer (114): - being axially delimited by two axial edges (114A, 114B) of the working layer, and - comprising wire reinforcements (114R) which extend from one to the other of the two axial edges of the working layer in a manner substantially parallel to each other in a main direction DT which forms an angle AT with a circumferential direction (Z) of the tire, the angle AT being, in absolute value, from 10° to 60°, in which, in the case where the working reinforcement (113) is made up of several working layers, the angles AT respectively associated with the working layers are identical to each other, in which the tire (100) comprises a carcass reinforcement (140), which is arranged radially inside the crown reinforcement (112) and which is made up of a single carcass layer (141) or of several carcass layers which are radially superimposed in the crown, the or each carcass layer (141): - being anchored in each bead (130) and extending from one to the other of the beads passing through each flank (120) and the top (110), - being axially delimited by two axial edges of the carcass layer, and

2.

3.

4.

5. - comprising wire reinforcements (141R) which extend from one to the other of the two axial edges of the carcass layer in a main direction DC which: - in each of two lateral portions (141F) of the carcass layer, arranged respectively in the sidewalls (120), forms an angle ACF with the circumferential direction (Z) of the tire, the angle ACF being, in absolute value, from 80° to 90°, and - in a top portion (141S) of the carcass layer, extending axially in radial line with the working reinforcement (113), forms an angle ACS with the circumferential direction (Z) of the tire, the angle ACS being, in absolute value, from 30° to 80° and having an orientation opposite to that of the angle(s) AT, the cord reinforcements of the carcass layer being substantially parallel to each other in the top portion of the carcass layer, in which, in the case where the carcass reinforcement (140) is made up of several carcass layers, the angles ACS respectively associated with the carcass layers are identical to each other, and in which the working reinforcement (113) has a breaking force, expressed in daN / mm, which is at least equal to 11.5*Tx+18.7 and the carcass reinforcement (140) has a breaking force, expressed in daN / mm, which is at least equal to l.8*Tx+16.0, where Tx is a dimensionless rate which is equal to RT / RI where RT and RI are measured radii,in the inflated mounted state of the tire (100), radially between an axis of rotation (XI00) of the tire and, respectively, a most radially outer end of the working reinforcement (113) and a most radially inner end of the tire. Tire according to claim 1, in which the working reinforcement (113) has a breaking force, expressed in daN / mm, which is at least equal to 12.9*Tx+21.7., A tire according to one of claims 1 or 2, wherein the carcass reinforcement (140) has a breaking force, expressed in daN / mm, which is at least equal to 1.8*Tx+18.

5. A tire according to any one of the preceding claims, wherein the Tx rate is from 1.2 to 1.

9. A tire according to any one of the preceding claims, wherein the angle AT is, in absolute value, from 15° to 45° and the angle ACS is, in absolute value, from 35° to 70°.

6. A tire according to any preceding claim, wherein the carcass reinforcement (140) consists of the single carcass layer (141) and the working reinforcement (113) consists of the single working layer (114).

7. A tire according to any preceding claim, wherein each of the wire reinforcements (114R) of the or each working layer (114) is a metal monofilament having a diameter which is equal to or greater than 0.33 mm, preferably less than 0.50 mm.

8. A tire according to any one of the preceding claims, wherein the crown reinforcement (112) further comprises a hooping layer (116), which: - is arranged radially between the tread (111) and the working reinforcement (113), - is delimited axially by two axial edges (116A, 116B) of the hooping layer, and - comprises at least one wire reinforcement (116R) which is wound circumferentially in a helix in a main direction DF from one of the two axial edges (116A, 116B) of the hooping layer (116) to the other, which main direction DF forms an angle AF with the circumferential direction (Z) of the tire (100), the angle AF being, in absolute value, at most 10°.

9. A tire according to claim 8, wherein the hooping layer (116) consists of a strip (117) which: - is wound circumferentially in a helix over several turns, and - is non-overlapping radially on itself in each of two axially outer portions (116E) of the hooping layer (116), which extend axially inward from respectively one and the other of the two axial edges (116A, 116B) of the hooping layer and which each have an axial width (LFE) which is equal to at least 12.5% ​​of the axial width (LT) of the or each working layer (114).

10. A tire according to claim 9, wherein the strip (117) includes, on each axial side of a median plane (M) of the tire (100), an axially outermost point (PI 17.1, PI 17.2) which is axially further from the median plane than the corresponding axial edge (114A, 114B) of the or each working layer (114).

Images