Tire comprising a low angle belt

Abstract

The present invention relates to a tire comprising a tread and a belt portion located radially below the tread wherein the belt portion comprises a pair of working belts and a low angle belt. The low angle belt has a reinforcing element at an angle of less than 5 DEG with respect to the circumferential direction of the tire. In a first aspect, the low angle belt includes a first layer and one or more further layers, where the first layer extends over at least 70% of the axial width of the axially maximum working belt, and where each of the one or more further layers extends over at most 50% of the width of the axially maximum working belt, and is disposed radially below one of the shoulder grooves.

Description

Technical Field

[0001] The invention relates to a tyre comprising a low-angle belt. In particular, the tyre can be a truck tyre. Furthermore, the invention relates to a method of shaping such a tyre. Background Art

[0002] Modern truck tires should meet many different performance requirements, such as low rolling resistance and / or high wear resistance. It is also desirable that such tires are robust. In particular, the forces in the grooves and / or shoulder regions of the tire should be reduced. For example, it is possible to reduce such forces by providing a corresponding tread construction. Although progress has been made in the past few decades in developing robust tires, such as robust truck tires, there is still much room for improvement. Summary of the invention

[0003] In a first aspect of the invention, the invention relates to a tire comprising a tread and a belt portion located radially below the tread, wherein the tread has two shoulder portions and wherein each shoulder portion comprises a shoulder groove. The belt portion comprises a pair of working belts and a low-angle belt, wherein the low-angle belt has a reinforcing element, the angle of the reinforcing element to the circumferential direction of the tire being less than 5°. The low-angle belt comprises a first layer and one or more further layers, wherein the first layer extends over at least 70% of the axial width of the axially largest working belt. Each of the one or more further layers of the low-angle belt extends over at most 50% of the axial width of the axially largest working belt and is arranged radially below one of the shoulder grooves.

[0004] In a second aspect of the invention, the invention relates to a tire comprising a tread and a belt portion located radially below the tread, wherein the belt portion comprises a pair of working belts and a low-angle belt, the low-angle belt comprising at least one ply strip. The ply strip has parallel reinforcing elements, and the angle of the parallel reinforcing elements to the circumferential direction of the tire is less than 5°. The pair of working belts comprises a first working belt and a second working belt, wherein each of the pair of working belts comprises parallel reinforcing elements, and wherein the reinforcing elements of the first working belt and the reinforcing elements of the second working belt cross each other at opposite angles. Still according to the second aspect of the invention, the difference between i) the absolute value of the angle of the reinforcing elements of the first working belt and the circumferential direction and ii) the absolute value of the angle of the reinforcing elements of the second working belt and the circumferential direction is at least 2°.

[0005] In a third aspect of the invention, the invention relates to a tire comprising a tread and a belt portion located radially below the tread, wherein the tread has a first shoulder portion located on a first lateral side of the tire and a second shoulder portion located on a second lateral side of the tire, the second lateral side being opposite to the first side. The belt portion comprises a pair of working belts and a low-angle belt, wherein the low-angle belt comprises at least one spirally wound cord layer strip, the at least one spirally wound cord layer strip comprising at least one elongated reinforcing element, the at least one elongated reinforcing element being at an angle of less than 5° to the circumferential direction of the tire. Furthermore, the low-angle belt comprises a first layer, a second layer and a third layer, the layers being formed by the at least one spirally wound cord layer strip. The first layer extends over at least 70% of the axial width of the axially largest working belt, and the second layer is arranged radially below the first layer and radially below the first shoulder portion. The third layer is arranged radially above the first layer and radially below the second shoulder portion, and each of the second layer and the third layer extends over at most 50% of the axial width of the axially largest working belt.

[0006] In a fourth aspect of the invention, the invention relates to a method for building a tire having a tread with two shoulder portions, each shoulder portion optionally having a circumferential shoulder groove, wherein the method comprises the steps of: providing at least one carcass ply; applying a first working belt to the at least one carcass ply; and applying a low-angle belt to the first working belt, comprising steps a) to c):

[0007] a) in a first winding step, winding a ply strip around the first working belt so as to form a circumferential band of the low-angle belt extending over an axial portion of the first working belt radially below a first of the shoulder portions;

[0008] b) continuing to wind the same ply strip in a second winding step in an axial orientation opposite to that in the first winding step so as to form another layer of the low-angle belt, the other layer covering at least 70% of the width of the first working belt and at least partially covering the belt formed in the first winding step;

[0009] c) in a third winding step, continuing to wind the same carcass strip in the same axial orientation as in the first winding step to form an additional circumferential band of the low-angle belt, which extends over the axial portion of the low-angle belt formed in the second winding step and is located radially below the second shoulder portion in the shoulder portion.

[0010] The present invention provides the following technical solutions:

[0011] 1. A tire comprising a tread and a belt portion located radially below the tread,

[0012] The tread has two shoulder portions, each of which includes a shoulder groove.

[0013] Wherein, the belt portion includes a pair of working belts and a low-angle belt,

[0014] wherein the low-angle belt has reinforcing elements, the angle of the reinforcing elements to the circumferential direction of the tire is less than 5°, and

[0015] wherein the low-angle belt comprises a first layer and one or more additional layers,

[0016] wherein said first layer of said low angle belt extends over at least 70% of the axial width of the axially largest working belt, and

[0017] wherein each of said one or more further layers of said low-angle belt is arranged radially below one of said shoulder grooves and extends over at most 50% of said axial width of said axially largest working belt.

[0018] 2. The tire according to claim 1, wherein the low-angle belt comprises a helically wound cord layer strip.

[0019] 3. The tire according to technical solution 1, wherein the one or more additional layers include a second layer arranged radially below the first shoulder groove, and a third layer arranged radially below the second shoulder groove.

[0020] 4. The tire according to claim 3, wherein each of the first layer, the second layer, and the third layer is formed by a spirally wound cord layer strip.

[0021] 5. The tire according to technical solution 4, wherein the first layer, the second layer and the third layer are formed by a single cord layer strip.

[0022] 6. The tire according to technical solution 5, wherein the second layer is located radially below the first layer, and the third layer is located radially above the first layer.

[0023] 7. The tire according to Technical Solution 4, wherein both the second layer and the third layer are located radially below the first layer or radially above the first layer.

[0024] 8. The tire according to technical solution 4, wherein the cord layer strip has an axial width in the range of 1.5 mm to 25 mm and a radial thickness in the range of 0.5 mm to 3 mm.

[0025] 9. The tire according to technical solution 4, wherein the cord layer strip includes from 1 to 5 parallel elongated reinforcing elements.

[0026] 10. The tire according to technical solution 9, wherein the reinforcing element is one or more of a metal cord and a metal wire.

[0027] 11. The tire according to technical solution 1,

[0028] Wherein, the pair of working belts comprises a first working belt and a second working belt,

[0029] Wherein, the low-angle belt is arranged between the first working belt and the second working belt,

[0030] wherein each of the pair of working belts comprises parallel reinforcing elements, and

[0031] The reinforcing elements of the first working belt and the reinforcing elements of the second working belt cross each other at opposite angles.

[0032] 12. The tire according to technical solution 11,

[0033] wherein the absolute value of the angle between the reinforcing element of each working belt and the circumferential direction ranges from 10° to 50°, and

[0034] Therein, the difference between i) the absolute value of the angle of the reinforcing element of the first working belt and ii) the absolute value of the angle of the reinforcing element of the second working belt is at least 2°.

[0035] 13. The tire according to technical solution 1,

[0036] wherein each of the pair of working belts comprises parallel reinforcing elements, and

[0037] Therein, the reinforcing elements of the working belt and the reinforcing elements of the low-angle belt are metal cords having a relative elongation higher than 0.2% and lower than 0.35% at 10% of their breaking force.

[0038] 14. The tire according to technical solution 1, wherein the tire further comprises one or more of the following:

[0039] a top belt arranged radially above the low-angle belt and the pair of working belts and comprising parallel reinforcing elements, the angles of the parallel reinforcing elements with the circumferential direction of the tire being in the range of 8 EPI to 14 EPI, and wherein the top belt is axially narrower than each of the working belts and the first layer of the low-angle belt;

[0040] A transition belt arranged radially below the low-angle belt and the pair of working belts, wherein the transition belt includes parallel reinforcing elements, the angles of the parallel reinforcing elements to the circumferential direction of the tire are in the range of 35° to 90°, and wherein the transition belt is axially narrower than each of the working belts and the first layer of the low-angle belt.

[0041] 15. A tire comprising a tread and a belt portion located radially below the tread, wherein the belt portion comprises a pair of working belts and a low-angle belt, the low-angle belt comprising a wound cord ply strip,

[0042] wherein the carcass strips have parallel reinforcing elements, the angle of the parallel reinforcing elements with the circumferential direction of the tire being less than 5°; and

[0043] wherein the pair of working belts comprises a first working belt and a second working belt, wherein each of the pair of working belts comprises parallel reinforcing elements, and wherein the reinforcing elements of the first working belt and the reinforcing elements of the second working belt cross each other at opposite angles,

[0044] wherein the absolute value of the angle between the reinforcing element of each working belt and the circumferential direction ranges from 10° to 50°, and

[0045] Therein, the difference between i) the absolute value of the angle of the reinforcing element of the first working belt strand and the circumferential direction and ii) the absolute value of the angle of the reinforcing element of the second working belt strand and the circumferential direction is at least 2°.

[0046] 16. The tire according to technical solution 15, wherein the absolute value of the angle of the radially inner working belt is 2° to 10° greater than the absolute value of the angle of the radially outer working belt.

[0047] 17. The tire according to technical solution 15,

[0048] The tread has two shoulder portions, each shoulder portion includes a shoulder groove, and

[0049] wherein the low-angle belt comprises a first layer and one or more additional layers,

[0050] wherein said first layer of said low-angle belt extends over at least 70% of the axial width of the axially largest working belt,

[0051] wherein each of said one or more further layers of said low-angle belt extends over at most 50% of said width of said axially largest working belt and is arranged radially below one of said shoulder grooves, and

[0052] Therein, the reinforcing elements of the working belt and the reinforcing elements of the low-angle belt have a relative elongation at 10% of their breaking force in the range of 0.2% to 0.29%.

[0053] 18. The tire according to claim 17, wherein all layers of the low-angle belt are formed by a single cord layer strip.

[0054] 19. A tire comprising a tread and a belt portion located radially below the tread,

[0055] wherein the tread has a first shoulder portion located on a first lateral side of the tire and a second shoulder portion located on a second lateral side of the tire, the second lateral side being opposite the first side;

[0056] Wherein, the belt portion includes a pair of working belts and a low-angle belt,

[0057] wherein the low-angle belt comprises at least one helically wound ply strip, the at least one helically wound ply strip comprising at least one elongated reinforcing element, the at least one elongated reinforcing element being at an angle of less than 5° to the circumferential direction of the tire, and

[0058] wherein the low-angle belt comprises a first layer, a second layer and a third layer, each of which is formed by the at least one spirally wound cord layer strip,

[0059] wherein the first layer extends over at least 70% of the axial width of the axially largest working band,

[0060] wherein the second layer is arranged radially below the first layer and radially below the first shoulder portion,

[0061] wherein the third layer is arranged radially above the first layer and radially below the second shoulder portion, and

[0062] wherein each of the second layer and the third layer extends over at most 50% of the axial width of the axially largest operating band.

[0063] 20. The tire according to technical solution 19, wherein the tire is one or more of the following:

[0064] One of 22.5-inch tires and 24.5-inch tires;

[0065] Truck tires;

[0066] A tire having at least one steel reinforced carcass ply;

[0067] A tire comprising a steel reinforced working belt and a reinforced low angle belt formed from steel reinforced ply strips. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] The present invention will now be described by way of example and with reference to the accompanying drawings, in which:

[0069] Figure 1 is a schematic cross section of a tire according to a first embodiment of the present invention;

[0070] Figure 2 is a schematic cross section of another tire according to a second embodiment of the present invention;

[0071] Figure 3 Shows Figure 1 and Figure 2 A schematic cross-section of an alternative belt portion of one of the tires of FIG.

[0072] Figure 4 Shows Figure 1 and Figure 2 another schematic cross-section of another alternative belt portion of one of the tires of; and

[0073] Figure 5 Shows Figure 1 and Figure 2 Still another schematic cross-section of a third alternative belt portion of one of the tires shown in , wherein the alternative includes a non-reinforcing filler filling the space between two axially opposed layers of a low-angle belt. DETAILED DESCRIPTION

[0074] In a first aspect, the invention relates to a tire comprising a tread and a belt portion located radially below the tread, wherein the tread has two shoulder portions, each of which comprises a preferably circumferentially extending shoulder groove. The belt portion comprises a pair of working belts and a low-angle belt, wherein the low-angle belt has reinforcing elements, the angle of the reinforcing elements to the circumferential direction of the tire being less than 5° (preferably less than 2° or 1°). The low-angle belt comprises a first layer and one or more further layers, wherein the first layer extends over at least 70% (preferably over at least 75%, and / or less than 95%) of the axial width of the axially largest working belt. Each of the one or more further layers of the low-angle belt extends over at most 50% (preferably at most 30%, and / or preferably over at least 5%) of the axial width of the axially largest working belt and is arranged radially below one of the shoulder grooves.

[0075] It has been found that such a construction of a tire with a pair of working belts and a low-angle belt, in particular including a layer arranged radially below the shoulder grooves, improves the robustness of the tire, in particular in the shoulder region of the tread and / or belt portion. In particular, such a multilayer design of the low-angle belt contributes to improving the durability of the low-angle belt, and in particular its reinforcement, in the shoulder region of the tire.

[0076] In one embodiment, the low-angle belt comprises at least one ply strip. The ply strip is preferably a wound ply strip. It can be considered as being wound (e.g., helically / spirally wound) around the axial direction of the tire, for example to form at least one layer of the low-angle belt. The strip may be wound at an angle of less than 5° to the circumferential direction of the tire. Preferably, this angle is between 0.1° and 4°, or between 0.1° and 2°, or even more preferably between 0.2° and 1°. The angle is preferably the same angle as the angle of the parallel and / or elongated reinforcing elements of the ply strip. The reinforcing elements of the ply strip are preferably coated (coated) with a rubber composition so as to form the ply strip. In other words, the ply strip comprises reinforcing elements coated with a rubber composition.

[0077] In another embodiment, each of the one or more further layers (e.g. the second layer and / or the third layer) extends over an axial width corresponding to 5% to 30% (preferably 5% to 20%) of the axial width of the axially largest working belt. Alternatively or in addition, each of the one or more further layers (e.g. the second layer and / or the third layer) extends over an axial width corresponding to a range of 90% to 300% (preferably 100% or 110% to 250%) of the axial width of the (radially outer or outermost) opening of the respective shoulder groove, which is located radially above the respective further layer of the low-angle belt.

[0078] In another embodiment, the one or more further layers comprise a second layer arranged radially below the first shoulder groove, and a third layer arranged radially below the second shoulder groove.Preferably, the low-angle belt comprises only these three layers.

[0079] In another embodiment, the tread comprises four circumferential grooves, including two shoulder grooves, wherein one of the shoulder grooves is located at each axially / laterally outer side of the tread.

[0080] In yet another embodiment, the axially largest working belt (which is preferably the radially inner working belt) extends over an axial width in the range of 110% to 200%, preferably from 115% to 160%, of the axial distance between the axially (and radially) outer edges of the shoulder grooves. The axially (and radially) outer edges of the shoulder grooves can also be described as the axially outer edges of the radially outer openings of such grooves.

[0081] In another embodiment, each of the first, second and third layers is formed by at least one ply strip comprising reinforcing elements. Possibly, each layer is formed by one or more separate ply strips. Optionally, each strip is wound and / or constructed as mentioned above.

[0082] In another embodiment, the first layer, the second layer and the third layer are formed by the same cord layer strip. For example, it is possible that the second layer is spirally wound around the radially lower working belt from an axially inner position toward a first axially outer position. Starting from the first axially outer position, the strip is radially wound on top of the second layer in an axially inner direction to form the first layer, thereby covering at least 70% of the axial width of the axially largest working belt. Starting from the second axially outer (or outermost) position of the first layer (for example, on the opposite axial / lateral side of the tire), the axial winding direction of the strip is reversed to provide the third layer on top of the first layer. Providing all three layers using one strip is particularly fast and cost-effective. Moreover, different tire widths and diameters can be constructed using this method, for example by using only a single strip type.

[0083] In another embodiment, one or more of the first layer, the second layer, and the third layer are each formed from at least one separate ply strip.

[0084] In yet another embodiment, the second layer is located radially below the first layer, and the third layer is located radially above the first layer.This preferred configuration is easy to manufacture in one strip winding step.

[0085] In yet another embodiment, both the second layer and the third layer are located radially below or radially above the first layer. It is also possible that the second layer and the third layer are arranged at substantially the same radial height. However, each of the second layer and the third layer preferably forms a circumferential band located radially below each shoulder groove or shoulder of the tire. The position radially below each shoulder groove or shoulder of the tire does not exclude that one or more additional belts are arranged radially above the second layer and / or the third layer between the second layer / third layer and the shoulder grooves.

[0086] In yet another embodiment, the low-angle belt (including its layers) is radially disposed between two of the pair of working belts.

[0087] In yet another embodiment, the ply strip has an axial width in the range of 1.5 mm to 25 mm (preferably from 3 mm to 16 mm, or from 3 mm to 9 mm), and / or a radial thickness in the range of 0.5 mm to 3 mm (preferably from 1 mm to 3 mm). Such radial thickness values ​​may also be applicable to other belts or belt plies mentioned herein, including one or more of working belts, transition belts, and top belts.

[0088] In yet another embodiment, the ply strip comprises from 1, preferably from 2 to 5 parallel reinforcing elements selected from one or more of cords and wires.

[0089] In yet another embodiment, the ply strip has a parallel reinforcement element density ranging from 10 EPI to 20 EPI.

[0090] In yet another embodiment, the working belt has a parallel reinforcement element density ranging from 8 EPI to 15 EPI, preferably from 10 EPI to 14 EPI.

[0091] In yet another embodiment, the reinforcing element is one or more of the following: an elongated reinforcing element; a metal reinforcing element; a metal and / or hybrid cord, optionally comprising a plurality of metal wires / filaments. The preferred metal herein is steel. The metal reinforcing element may optionally be coated with brass. In a most preferred embodiment, the reinforcing element is a brass coated steel cord, in particular comprising a plurality of steel wires.

[0092] In yet another embodiment, the reinforcing elements (e.g., of the working belt and / or the low-angle belt) are metal cords having a configuration a+bxd, wherein a ranges from 2 to 5 (wires / filaments), b ranges from 2 to 4 (wires / filaments), and d (the corresponding diameter of the wires / filaments) ranges from 0.2 mm to 0.5 mm (preferably from 0.3 mm to 0.45 mm). In particular, this configuration is considered to be relatively open to rubber penetration, which further improves the robustness of the tire.

[0093] In another embodiment, the cords (e.g., of the working belts and / or low-angle belts, preferably all of them) have a configuration 4+3x0.35. In this example, the four inner filaments (or metal wires) are straight and three filaments are twisted on the four inner filaments. Alternatively, the thickness of the individual metal wires / filaments forming the cords is preferably in the range t of 0.15 to 0.35 mm. Thus, the metal cords may have a configuration 4+3x t, such as with t as mentioned above.

[0094] In another embodiment, the reinforcing elements or cords have an elongation at 10% of their breaking force which is higher than 0.2% or 0.21% and preferably lower than 0.4%, 0.35%, 0.3% or 0.29% (measured after extraction from the cured tire). Preferably, such values ​​apply to the cords of the working belt and / or the cords of the low-angle belt. The cord elongation or tensile test of the cords is carried out here according to ISO 6892-1B with a preload of 20 MPa on the cords extracted from the cured tire.

[0095] In yet another embodiment, the pair of working belts includes a first working belt and a second working belt, wherein the low-angle belt is arranged between the first working belt and the second working belt, wherein each working belt in the pair of working belts includes parallel reinforcing elements, and wherein the reinforcing elements of the first working belt and the reinforcing elements of the second working belt cross each other at opposite angles, or in other words, cross each other at opposite angular orientations.

[0096] In yet another embodiment, the absolute value of the angle of the (corresponding) reinforcing element of each working belt with the circumferential direction ranges from 10° to 50°, preferably from 15° to 30°, or more preferably from 15° to 25°. Alternatively or in addition, the difference between the absolute value of the angle of the reinforcing element of i) the first working belt and the absolute value of the angle of the reinforcing element of ii) the second working belt is at least 2° (preferably at least 3° and / or at most 15°, or at most 8°, or only at most 6°). Preferably, the radially innermost working belt has a larger absolute angle. This preferably makes the angle closer to the angle of the at least one carcass ply, the angle of the at least one carcass ply with the circumferential direction preferably being 90°. Preferably, in such an embodiment, the belt portion does not have a transition belt between the radially innermost working belt and the adjacent carcass ply, the adjacent carcass ply being arranged radially below the innermost working belt.

[0097] In yet another embodiment, each working belt of the pair of working belts comprises parallel reinforcing elements, wherein at least one of i) the reinforcing elements of the working belts and ii) the reinforcing elements of the low-angle belts has a relative elongation at 10% of their / the breaking force, which is lower than 0.4% (preferably lower than 0.3% or lower than 0.29%). Optionally, the elongation is at least 0.2% or 0.21%.

[0098] In yet another embodiment, the tire further comprises a top belt arranged radially above the low-angle belt and the pair of working belts. The top belt preferably comprises parallel reinforcing elements, the angle of the parallel reinforcing elements to the circumferential direction of the tire being in the range of 10° to 25°, preferably 14° to 21°. Optionally, the top belt is axially narrower than each of the working belts and the first layer of the low-angle belt.

[0099] In yet another embodiment, the top belt comprises a rubber composition reinforced by cords (e.g., metal, textile or hybrid cords). Preferably, the cords are metal cords. Suitable cord constructions include, for example, 3+2x0.35 and / or 5x0.35 and / or 5x0.38.

[0100] In yet another embodiment, the belt portion has exactly four belts, namely two working belts, a low angle belt (having multiple layers, preferably exactly three layers) and a top belt.

[0101] In yet another embodiment, the top belt has an axial width of at least 50% of the axial width of the axially largest working belt and / or the radially innermost working belt. Additionally or alternatively, the axial width of the top belt is in the range of 50% to 90% (preferably 60% to 80%) of the axially largest working belt and / or the radially innermost working belt.

[0102] In yet another embodiment, the tire further comprises a transition belt arranged radially below the low-angle belt and the pair of working belts. Optionally, the transition belt comprises parallel reinforcing elements, the angle of the parallel reinforcing elements to the circumferential direction of the tire is in the range of 35° to 90° (preferably 50° to 90°, or more preferably 50° to 75°). Preferably, the transition belt is axially narrower than each of the working belts and the first layer of the low-angle belt.

[0103] In yet another embodiment, the tire further comprises a rubber cord layer arranged between the radially inner working belt and the radially outermost carcass cord layer. Such a rubber cord layer preferably has no reinforcement. Optionally, it has a radial thickness in the range of 0.5 mm to 3 mm, preferably in the range of 1 mm to 2.5 mm. Preferably, its hardness is at most the hardness of the rubber composition of the radially inner working belt. Preferably, the hardness of the rubber composition of the rubber cord layer is at least 5% lower than the hardness of the rubber composition of the radially inner working belt. Hardness is determined herein as G'(1%). G' is measured herein using the RPA 2000 of Alpha Technologies. TM Rubber Process Analyzer acquired at 100°C and 1 Hz at 1% strain based on ASTM D5289 or equivalent.

[0104] In yet another embodiment, one or more of the first, second and third layers (of the low-angle belt) do not extend axially beyond adjacent axially outer edges of the one or more of the working belts.

[0105] In yet another embodiment, one or more of the first, second, and third layers extend axially beyond adjacent axially outer edges of the top band (if present). Preferably, one or more of the first, second, and third layers extend beyond the axially outer edges of the top band by less than 10% (preferably less than 5%) of the total axial width of the top band.

[0106] In yet another embodiment, the belt portion has one or more of the following: a first layer of low-angle belts, which is axially larger than the top belt; a first working belt, which is axially larger than the first layer; and a second working belt, which is axially larger than the first working belt (and which is preferably arranged between the top belt and the low-angle belt), wherein the first working belt is preferably arranged radially below each layer of the top belt, the second working belt and the low-angle belt.

[0107] In another embodiment, each of the belts extends in an axially outward direction so as to support a shoulder groove on each lateral / axial side of the tire. In other words, each belt optionally extends to an outer axial position that is axially outward of the radially outermost end of the axially outer sidewall of the corresponding shoulder groove.

[0108] In yet another embodiment, at least one of the working belt and / or the low-angle belt has a rubber permeability of at least 90%, preferably at least 95%, even more preferably at least 99% or 100%. The rubber permeability is measured herein by air permeability testing according to Survey of Mechanical Properties of Steel Cord and Related Test Methods (Special Technical Publication 694, ASTM, 1980) by L. BOURGOIS. Such high rubber permeability provides even higher durability of the corresponding belt layer and helps to avoid cord breakage.

[0109] According to a second aspect of the invention, the invention relates to a tire comprising a tread and a belt portion located radially below the tread, wherein the belt portion comprises a pair of working belts and a low-angle belt, the low-angle belt comprising at least one ply strip. The ply strip has parallel reinforcing elements, and the angle of the parallel reinforcing elements to the circumferential direction of the tire is less than 5°. The pair of working belts comprises a first working belt and a second working belt, wherein each of the pair of working belts comprises parallel reinforcing elements, and wherein the reinforcing elements of the first working belt and the reinforcing elements of the second working belt cross each other at opposite angles, or in other words, cross each other at opposite angles. In addition, the absolute value of the angle of the reinforcing elements of each working belt to the circumferential direction ranges from 10° to 50°, preferably from 15° to 30°, or 15° to 25°. Still according to the second aspect of the invention, the difference between i) the absolute value of the angle of the reinforcing elements of the first working belt bundle with the circumferential direction and ii) the absolute value of the angle of the reinforcing elements of the second working belt bundle with the circumferential direction is at least 2° (preferably at least 3° and / or at most 10°, or at most 8°, or only at most 6°).

[0110] This combination of a low angle belt and a pair of working belts has been found to be particularly desirable for providing a strong belt portion for a tire, such as a truck tire.

[0111] Preferably, the low-angle belt is disposed between the first working belt and the second working belt.

[0112] In one embodiment, the absolute value of the angle of the radially inner working belt is from 2° to 10° (preferably from 3° to 8°) greater than the absolute value of the angle of the radially outer working belt. In particular, the inventors have found that such a relatively small difference is advantageous for the durability of the belt portion.

[0113] In another embodiment, the tread has two shoulder portions, wherein each shoulder portion optionally comprises a shoulder groove, and wherein the low-angle belt comprises a first layer and one or more further layers. Optionally, the first layer of the low-angle belt extends over at least 70% of the axial width of the axially largest working belt. Additionally or alternatively, each of the one or more further layers of the low-angle belt extends over at most 50%, preferably at most 30%, of the width of the axially largest working belt, and / or is arranged radially below one of the shoulder grooves, in particular to support at least the entire axial width of the respective shoulder groove (measured at the radially outermost opening of such shoulder groove).

[0114] In yet another embodiment, the reinforcing elements of the working belt and / or the reinforcing elements of the low-angle belt have a relative elongation at 10% of their / the breaking force ranging between 0.2% and 0.29%.

[0115] In yet another embodiment, one or more layers, preferably all layers, of the low-angle belt are formed from a single ply strip.

[0116] In yet another embodiment, the tire is one or more of the following: a pneumatic tire; a radial tire; one of 17.5, 19.5, 22.5 and 24.5 inch tires; a truck tire; a tire having at least one steel reinforced carcass ply; a tire including a steel reinforced working belt and / or a reinforced low-angle belt formed by steel reinforced ply strips.

[0117] In a third aspect, the invention relates to a tire comprising a tread and a belt portion radially below the tread, wherein the tread has a first shoulder portion located on a first lateral (or axial) side of the tire and a second shoulder portion located on a second lateral (or axial) side of the tire, the second lateral (or axial) side being opposite to the first side. The belt portion comprises a pair of working belts and a low-angle belt, wherein the low-angle belt comprises at least one helically wound cord strip (e.g., helically wound about an axial direction), the at least one helically wound cord strip comprising at least one elongated reinforcing element (such as at least one cord), the at least one elongated reinforcing element being at an angle of less than 5° to the circumferential direction of the tire. Furthermore, the low-angle belt comprises a first layer, a second layer and a third layer, the layers being formed by the at least one helically wound cord strip. The first layer extends over at least 70% of the axial width of the axially largest working belt, and the second layer is arranged radially below the first layer and radially below the first shoulder portion, and optionally radially below the circumferential shoulder groove of the portion. The third layer is arranged radially above the first layer and radially below the second shoulder portion, and optionally radially below the circumferential shoulder groove of said portion, wherein each of the second and third layers extends over at most 50% (preferably at most 30% and / or at least 5% or 10%) of the axial width of the axial maximum working belt.

[0118] In one embodiment, the second layer and / or the third layer are arranged axially outside of a respective shoulder groove of a respective shoulder portion.

[0119] It is emphasized herein that embodiments and / or features of the first aspect and / or the second aspect can also be applied to the third aspect.

[0120] According to a fourth aspect of the invention, the invention relates to a method of building a tire, such as one of the tires mentioned above, the tire having a tread, the tread having two shoulder portions, each shoulder portion preferably having a circumferential shoulder groove, wherein the method comprises one or more of the following steps:

[0121] providing at least one carcass ply, such as on a tire building drum;

[0122] Optionally, applying a transition belt to the carcass ply;

[0123] applying a first working belt to the carcass ply and / or the transition belt;

[0124] Applying the low-angle belt to the first working belt preferably comprises one or more of the following sub-steps a) to c):

[0125] a) in a first winding step, winding a ply strip around (or around) the first working belt so as to form a circumferential band (or layer) of the low-angle belt extending over an axial portion of the first working belt, radially below the first one of the shoulder portions and / or the first one of the shoulder grooves (wherein said band or layer has an axial width of preferably at most 50% or 30% (and / or at least 5%) of the axial width of the first working belt);

[0126] b) continuing to wind the same ply strip in a second winding step (preferably in an axial orientation opposite to that in the first winding step) so as to form another layer of the low-angle belt, which further layer covers at least 70% (and / or at most 95%) of the width of the first working belt and preferably also covers said belt or layer formed in the first winding step;

[0127] c) in a third winding step, continuing to wind the same ply strip (preferably in the same axial orientation as in the first winding step) so as to form a further circumferential band (or layer) of the low-angle belt, extending over an axial portion of the low-angle belt and / or said further layer formed in the second winding step, radially below the second shoulder portion and / or second shoulder groove (on the side of the tire axially opposite to said first one of the shoulder portions and / or grooves), wherein the axial width of said further band (or layer) is preferably at most 50% or 30% (and / or at least 5%) of the axial width of the first working belt;

[0128] applying a second working belt to the low angle belt;

[0129] applying the top belt to the second working belt, wherein the second working belt and the top belt may optionally be applied together as one component to the low angle belt;

[0130] The tread is applied to the second working belt and / or the top belt (if present).

[0131] The above method provides a very efficient way to provide a low angle belt to increase the robustness of the belt portions and tread, such as the shoulder portions, especially the shoulder grooves.

[0132] In one embodiment, the first winding step, the second winding step and the third winding step are performed consecutively, for example in one pass.

[0133] In another embodiment, the winding is a helical winding, such as around an axial direction, and / or as described in other paragraphs herein.

[0134] It is emphasized that the method of building a tire is not limited to the steps mentioned and that such method does not exclude further manufacturing or mounting steps of further tire components, such as sidewalls, chafers, beads, apex, overlays, etc. Such steps may also be present between one or more of the steps mentioned above.

[0135] Figure 1 A tire 1 according to a preferred embodiment of the present invention is shown. The tire 1 has a tread 20, a pair of sidewalls 30, a pair of bead portions 40, a carcass ply 50, and an inner liner 60. Each bead portion 40 includes a bead 41 and a bead apex 42. In addition, the tire 1 has a belt portion 100, which includes a plurality of belts, including a first working belt 110, a second working belt 130, a low-angle belt 120 (sometimes also referred to as a zero-degree belt), and a top belt 140. According to Figure 1 In the embodiment of the present invention, the low-angle belt 120 includes three layers, namely a first layer 121, a second layer 122 and a third layer 123. Each of the second layer 122 and the third layer 123 is arranged radially below the corresponding shoulder groove 21 of the tread 20.

[0136] The first working belt 110 and the second working belt 130 have parallel and elongated reinforcements or reinforcement elements (in this case metal cords) with an angle ranging from 10° to 50° with the circumferential direction c. The reinforcement elements of the first working belt 110 cross the reinforcement elements of the second working belt 130 at an opposite angle orientation, wherein, in a preferred embodiment, the angle of the first working belt 110 with the circumferential direction c is 4° greater than that of the second working belt 130 with the circumferential direction c. Figure 1 As further schematically shown in FIG. 1 , the low-angle belt includes at least one ply strip wound to form the low-angle belt 120. In particular, in this example, the metal cords of the low-angle belt 120 (particularly in the ply strip of the low-angle belt 120) are at an angle of less than 1° to the circumferential direction c. The ply strip is spirally wound around the axial direction a on top of the circumferential first working belt 110. Figure 1 In the preferred embodiment shown in , the entire low-angle belt 120 including three layers is formed by a single ply strip. In particular, this ply strip is spirally wound from an axially inner position to an axially outer end position so as to form the second layer 122. After having reached the axially outer end position of the second layer 122, the ply strip is still wound around the axial direction of the tire 1, but moves in the axially inner direction during continued winding so as to form the first layer 121 ( Figure 1After the cord layer strip is continuously wound radially above the first working belt 110, the axial outward movement during winding stops and is reversed again at the axial outer end position on the right hand side of the tire 1, and so as to continue moving in the axial inward direction of the tire 1 again during winding. By the axial inward movement, the third layer 123 of the low-angle belt 120 is formed. Finally, as soon as the third layer 123 of the desired width is obtained, the axial inward movement and winding are stopped. In the present embodiment, it is desirable that each of the second and third layers at least covers the bottom of the corresponding shoulder groove located radially above each of the second layer 121 and the third layer 123. The total axial width of the low-angle belt 120 is preferably greater than the total axial width of the top belt 140, for example, axially at least 1% greater and / or axially at most 10% greater than the axial width of the top belt 140. The width of the first working belt 110 is greater than the width of the second working belt 130, preferably in the range of 5% to 20% greater than the width of the second working belt 130. On the one hand, the total axial width of one of the second layer 122 and the third layer 123 of the low-angle belt 120 is preferably in the range of 10% to 30% of the axial width of the first working belt 110 (which in this case is the axially largest belt of the belt portion 100). On the other hand, the width of the second layer 122 or the third layer 123 of the low-angle belt 120 is preferably in the range of 90% to 250% of the axial width of the outermost opening of the corresponding shoulder groove 21 located radially above the second layer 122 or the third layer 123. In the present embodiment, the top belt 140 is the axially narrowest belt. As shown in the present embodiment, there are preferably four belts in total. In addition, the tread 20 preferably has four circumferential grooves. In an alternative embodiment, the tread has five such grooves.

[0137] Thus, the ply strips or in other words the spirally wound ply strips that form the layers of the low-angle belt 120 have a width in the range of 3 mm to 25 mm and a radial thickness in the range of 0.5 mm to 3 mm. In a preferred embodiment of the invention, the strips have a width of 5 mm and a thickness of about 2 mm. In another specific embodiment, the strips have a width of 15 mm and a thickness of 2 mm.

[0138] For better understandability, Figure 1 , an axial direction a, a circumferential direction c and a radial direction r are indicated. The axial direction a is parallel to the axis of rotation of the tire. The circumferential direction c is parallel to the circumference of the tire, and the radial direction r is perpendicular to the axial direction a and the circumferential direction c. It is emphasized that each of these directions can have a different orientation, so that a reference to one of these directions is generally not limited to a specific orientation unless otherwise indicated herein.

[0139] As mentioned above, Figure 1 is a schematic diagram. For example, Figure 1 The distances between the belts and / or layers shown in the drawings are shown to be larger than in reality. Therefore, the interstitial spaces between the depicted belt layers and / or belts will usually close when the tire is cured. The same applies to the further drawings shown in this article. Figure 2 Another embodiment of a tire 10 according to the invention is shown. Where appropriate, Figure 2 will with Figure 1 The same reference numerals are used for various components including the tread 20, shoulder grooves 21, sidewalls 30, bead portions 40, apex 42, beads 41, carcass ply 50, and inner liner 60. Figure 1 In contrast to the embodiment of the tire 1 shown in Figure 2 The tire 10 of the embodiment of the present invention has a different belt portion 200. The belt portion 200 includes a first working belt 210, a second working belt 230, a low angle belt 220 and a top belt 240. The low angle belt does not include three layers, but includes a single layer 220 formed by a spirally wound cord layer strip. In particular, the low angle belt does not include two additional layers arranged radially below each of the shoulder grooves 21. However, the low angle belt 220 also extends below each shoulder groove 21. In addition, the working belts 210, 230 each include parallel metal cords, which have an angle with the circumferential direction. The absolute value of the angle of the parallel cords of the first working belt 210 is 4° greater than the absolute value of the (relative) angle of the parallel cords of the second working belt 230. In particular, the cords of the first working belt 210 have an absolute angle of 23°, and the cords of the second working belt 230 have an absolute angle of 19°. It has been found that the combination of such a pair of working belts 210, 230 and a low-angle belt disposed radially between the two working belts 210, 230 results in an even more robust construction, further improving the robustness of the working belts. Figure 3 An alternative belt portion 300 that can be used in a tire, such as one of tire 1 or tire 10, is shown. The belt portion 300 includes a radially inner working belt 310, a radially outer working belt 330, a low angle belt 320 disposed between the first working belt 310 and the second working belt 330, and a top belt 340. The low angle belt 320 includes a first layer 321, a second layer 322, and a third layer 323. In this embodiment, each layer is formed by a separate ply strip. The remaining construction can be similar to that described with respect to Figure 2 The configurations described in the embodiments are the same or similar. Figure 3 Embodiments of the invention are also directed to providing second and third low-angle belt layers radially below the shoulder grooves (not explicitly shown herein).

[0140] Figure 4A further embodiment of a belt portion 400 is shown, which includes a first working belt 410, a second working belt 430, a low angle belt 420 and a top belt 440. The low angle belt 420 includes a first layer 421, a second layer 422 and a third layer 423, wherein each of the layers is formed by a separate ply strip. Figure 3 In contrast to the embodiment shown in FIG. 4 , the third layer 422 and the second layer 423 are arranged radially above the first layer 421, while in FIG. Figure 3 In the embodiment of FIG. 3 , a similar layer is arranged radially below the corresponding first layer 321 .

[0141] Figure 5 Another embodiment of a possible belt portion 500 is shown, which includes a belt portion with Figure 4 In particular, the belt portion 500 includes a first working belt 510, a second working belt 530, a low angle belt 520 and a top belt 540. The low angle belt 520 includes a first layer 521 and two radially outer layers 522 and 523, which are radially arranged on top of the first layer 521 and radially below the corresponding shoulder grooves (not explicitly shown herein). Figure 4 In addition to the construction shown in Figure 5 The belt portion 500 also has a filler layer 555 consisting of a spirally wound rubber strip which is not reinforced, in particular without fabric or metal cords. In the case where the layers of the low-angle belt (such as the second layer 522 and / or the third layer 523) are relatively thick, a filler layer can be used. However, such a provision is not essential, since typically the various belts of the tire will be attached to each other during tire curing.

[0142] In each of the non-limiting embodiments shown in the drawings herein, the low-angle belt has elongated reinforcing elements in the form of metal cords, in particular steel cords, which are preferably coated with brass. In a preferred example, they have the following cord construction: 4+3x0.35. In this example, the four inner filaments (or metal wires) are straight and three filaments are twisted on the four inner filaments, which provides a relatively open construction that allows, for example, good rubber (coating) penetration.

[0143] For example, the metal or steel cords in the working belt may have one of the following cord constructions: 3x7x0.22; 3x4x0.22; 4x4x0.22; 4+3x0.35; 3+2x0.35, and have an elongation at 10% of their breaking force that is greater than 0.4% and preferably less than 1%. The thickness of the individual metal wires forming such cords is preferably in the range of 0.15 to 0.35 mm.

[0144] However, even more preferred herein are working belts having the same or similar cords as the low-angle belts. For example, those working belts may have the following cord configurations: 4+3x0.35 and / or 3+2x0.35.

[0145] The cord may also have a construction selected from the following: 3+2x0.35; 3+3x0.35; 3+4x0.35; 4+2x0.35; 4+3x0.35; 4+4x0.35; 5+2x0.35; 5+3x0.35; 5+4x0.35; 4x6x0.19; 4x5x0.20; and a+bxd, wherein a ranges from 3 to 5, b ranges from 2 to 4, and d ranges from 0.2 mm to 0.5 mm (preferably from 0.3 mm to 0.45 mm).

[0146] The EPI of the cords in the working belt preferably ranges from 8 to 14 EPI. The EPI of the cords in the low-angle belt ply strips preferably ranges from 10 EPI to 20 EPI, preferably from 10 EPI to 16 EPI, or more preferably from 14 EPI to 16 EPI. Preferably, the EPI of the cords in the top belt ranges from 8 EPI to 14 EPI, preferably less than 10 EPI.

[0147] Preferably, the cords utilized herein have an elongation (or relative elongation) at 10% of their breaking force that is greater than 0.2%, preferably less than 0.4%.

[0148] about Figure 1 In view of the inventive example of a belt portion 100 shown in FIG. 1 , the inventors have performed a finite element analysis (FEA) comparing a tire having only a first layer of a low-angle belt (not shown) with a Figure 1 The analysis leads to the conclusion that by adding the third layer 123, the maximum forces in the low-angle belt are reduced by about 25%, which is a significant improvement. Thus, the durability of the tire is further improved.

[0149] In addition, the inventors have tested the rubber permeability in the belts and their layers used in the embodiments herein. The test results show 100% rubber permeability in the low-angle belt, including all its layers and across the entire axial width. The same applies to each of the working layers. This very high rubber permeability makes the tire stronger.

[0150] The present invention and optionally one or more of its embodiments contribute to providing a robust tire, in particular a tire with an advanced belt portion. For example, the stability of the shoulder and / or groove area can be improved. In addition, simple and / or cost-effective manufacturing is possible.

[0151] One or more of the above first, second, third and fourth aspects, and / or their corresponding embodiments and / or features may be combined with each other.

[0152] According to the description of the invention provided herein, changes in the present invention are possible. Although certain representative embodiments and details have been shown for the purpose of illustrating the present invention, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the scope of the present invention. Therefore, it will be understood that changes can be made in the specific embodiments described, and these changes will be within the complete expected scope of the present invention as defined by the following claims.

Claims

1. A tire comprising a tread and a belt portion located radially below the tread, in, The tread has two shoulder portions, each shoulder portion including a shoulder groove, Wherein, the belt portion includes a pair of working belts and a low-angle belt, wherein the low-angle belt has reinforcing elements, the angle of the reinforcing elements to the circumferential direction of the tire is less than 5°, and wherein the low-angle belt comprises a first layer and one or more additional layers, wherein said first layer of said low angle belt extends over at least 70% of the axial width of the axially largest working belt, and wherein each of said one or more further layers of said low-angle belt is arranged radially below one of said shoulder grooves and extends over at most 50% of said axial width of said axially largest working belt.

2. The tire according to claim 1, wherein: The low-angle belt includes a helically wound ply strip.

3. The tire according to claim 1, wherein: The one or more further layers include a second layer arranged radially below the first shoulder groove, and a third layer arranged radially below the second shoulder groove.

4. The tire according to claim 3, wherein: Each of the first layer, the second layer, and the third layer is formed from a helically wound ply strip.

5. The tire according to claim 4, wherein: The first layer, the second layer and the third layer are formed from a single ply strip.

6. The tire according to claim 5, wherein: The second layer is located radially below the first layer, and the third layer is located radially above the first layer.

7. The tire according to claim 4, wherein: Both the second layer and the third layer are located radially below the first layer or radially above the first layer.

8. The tire according to claim 4, wherein: The ply strip has an axial width in the range of 1.5 mm to 25 mm and a radial thickness in the range of 0.5 mm to 3 mm.

9. The tire according to claim 4, wherein: The ply strip comprises from 1 to 5 parallel elongated reinforcing elements.

10. The tire according to claim 9, wherein: The reinforcing elements are one or more of metal cords and metal wires.

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