WO2024200442A1

WO2024200442A1 - Pneumatic tyre wth belt

Info

Publication number: WO2024200442A1
Application number: PCT/EP2024/058117
Authority: WO
Inventors: Bernardus Antonius René Roelofs
Original assignee: Apollo Tyres Global R&D B.V.
Priority date: 2023-03-30
Filing date: 2024-03-26
Publication date: 2024-10-03

Abstract

The invention relates to a tyre (10) for a vehicle, the tyre (10) comprising a belt (22), wherein the belt (22) comprises a multilayer composite laminate comprising at least three superposed layers (24, 26, 28), each layer (24, 26, 28) comprising reinforcements (30, 32, 34) being embedded in a rubber, wherein a first layer (24) is arranged on a tread side of the tyre (10) and comprises first reinforcements (30) comprising a heat shrinkable material, wherein a second layer (26) is in contact with the first layer (24) and arranged under the first layer (24), wherein the second layer (26) comprises second reinforcements (26) comprising metal, wherein a third layer (28) is in contact with the second layer (26) and arranged under the second layer (26), wherein the third layer (28) comprises third reinforcements (34) comprising metal, wherein the first reinforcements (30) are assemblies (30) of yarn bundles (36), each yam bundle (36) comprising multiple filaments, and wherein each assembly (30) comprises at least two yarn bundles (36). The invention further relates to a corresponding wheel for a vehicle

Description

PNEUMATIC TYRE WTH BELT

FIELD OF THE INVENTION

The present invention relates to a tyre of vehicle having a belt. In particular the present invention relates to a tyre with a belt, wherein the belt comprises a multilayer composite laminate comprising at least three superposed layers, each layer comprising reinforcements being embedded in a rubber.

The present invention further relates to a corresponding wheel.

BACKGROUND OF THE INVENTION

Tyres are meant for commuting purpose, carrying tons of load, and are subjected to varying speed operation, road conditions, and driver expertise.

Tyres with a radial carcass reinforcement, also called radial tyres, are well known. These tyres generally comprise a tread, two inextensible beads, two flexible sidewalls connecting the beads to the tread and a belt arranged circumferentially between the carcass reinforcement and the tread.

Cords in the carcass reinforcement are radially disposed at an angle approximately 90° relative to the circumference of the tyre, giving the tyre its name “radial tyre”. The belt is provided as a reinforcing layer on the carcass reinforcement.

The belt is generally made up of at least two rubber plies, also referred to as working plies, which are superposed, usually reinforced with metal cords disposed substantially parallel to one another and inclined with respect to the median circumferential plane of the tyre. It is possible that these working plies are associated with further plies and/or fabrics. The primary function of the working plies is to give the tyre high drift thrust or cornering stiffness which is necessary for achieving good handling of the motor vehicle. In particular for tyres that need to be highly reliable for high speed applications, the belt may further comprise above the working plies - i.e. on the tread side - an additional layer , also referred to as cap ply, which is generally reinforced with “circumferential” reinforcing threads, which means that these reinforcing threads are disposed practically parallel to one another and extend substantially circumferentially around the tyre casing to form an angle preferably in a range from -5° to +5° with the median circumferential plane. The primary role of these circumferential reinforcing threads is to withstand the centrifuging of the crown at high speed. Typically cords - which are multiple yam bundles twisted together - are used as reinforcements.

Such belt structures, having a multilayer composite laminate comprising at least one cap ply and two generally metallic working plies, are well known to those skilled in the art.

For example, EP 3 426 503 Bl describes a radial tyre with a belt comprising a multilayer composite laminate with at least three superposed layers, each layer comprising reinforcements being embedded in a rubber.

For reducing the energy consumption of the vehicles fitted with such tyres it is desirable to also reduce the rolling resistance and/or the weight of the tyre. Thus, there is a permanent need for providing lighter tyres without comprising handling, durability and/or high-speed performance of the tyre having reduced rolling resistance.

The present invention has the objective to provide a lighter tyre with reduced rolling resistance without comprising handling, durability and/or high-speed performance of the tyre.

SUMMARY OF THE INVENTION

This and other objects are achieved by providing a tyre according to claim 1 as well as a wheel according to claim 17. Preferred embodiments of the invention are given by the dependent claims, which can constitute each solely or in combination an aspect of the invention. In a first aspect, the invention provides a tyre for a vehicle comprising a belt, wherein the belt comprises a multilayer composite laminate comprising at least three superposed layers, each layer comprising reinforcements being embedded in a rubber, wherein a first layer is arranged on a tread side of the tyre and comprises first reinforcements comprising a heat shrinkable material, wherein a second layer is in contact with the first layer and arranged under the first layer, wherein the second layer comprises second reinforcements comprising metal, wherein a third layer is in contact with the second layer and arranged under the second layer, wherein the third layer comprises third reinforcements comprising metal, wherein the first reinforcements are assemblies of yam bundles, each yarn bundle comprising multiple filaments, and wherein each assembly comprises at least two yarn bundles.

The object is also solved by a wheel for a vehicle comprising a tyre rim for being connected to an axle of the vehicle and the above tyre mounted to the tyre rim.

Using in the first layer assemblies of yam bundles, with at least two yarn bundles per assembly, and wherein each yam bundle comprises multiple filaments, makes it possible to reduce the overall thickness of the belt without affecting the durability of the tyre negatively. It makes it possible to use less rubber in the belt making the belt lighter. Furthermore, it was found that using the assemblies of yarn bundles, with at least two yarn bundles per assembly, makes it possible to reduce the ratio of rubber to reinforcement in the first layer, thus reducing the thickness of the layer without compromising the durability of the tyre.

The assembly of yarn bundles are formed by at least two yam bundles that are grouped together. In other words, instead of using cords, which are multiple yarn bundles twisted together, the assemblies of yam bundles are used as first reinforcements. Within one assembly the yarn bundles are preferably not spaced apart from each other but are directly adjacent to each other. The induvial assemblies on the other hand are preferably spaced apart from each other.

The yarn bundle comprises multiple filaments, typically in a magnitude of hundreds of filaments. A filament is a very long continuous fiber. The filaments of the yam bundle are very thin and have typically a diameter in a magnitude of micrometers. The multiple filaments in one yam bundle can be twisted or untwisted. Preferably, the multiple filaments in the yam bundle are slightly twisted to form the yarn bundle.

In other words, by using the described belt structure, the thickness of the rubber above and below the reinforcements embedded in the rubber can be kept constant, even though the thickness of the cap ply - i.e. the thickness of the first layer - is reduced. Hence, the durability of the tyre is not negatively affected, even though a thinner belt is used.

The thinner belt structure comes not only with the advantage that the weight of the tyre is reduced, but the belt structure has also the advantage that the rolling resistance and the hysteresis of the tyre is reduced. Thus, the consumption of energy of vehicles fitted with such a tyre is reduced.

Preferably the tyre is configured as radial tyre and more particularly as radial-ply tyre. Further preferably the reinforcements being embedded in the rubber are extending unidirectional within each layer. Further preferably the first reinforcements, i.e. the assemblies of yam bundles extend circumferentially around the tyre casing and further preferably form an angle of -5 to +5 degree and preferably of 0 degree with the median circumferential plane. Further preferably the second and third reinforcements extend circumferentially around the tyre casing and further preferably form an angle of -15 to +35 degrees with the median circumferential plane.

Within the context of this application the circumferential direction of the tyre is preferably the direction along the tyre rolling movement. As used herein, the terms “radial direction”, and/or “radially” refer to a direction orthogonal to the circumferential direction and can either mean towards an axis of rotation of the tyre or away from the axis of rotation. The “axial direction” is a direction substantially parallel to the axis of rotation of the tyre.

The ’’median circumferential plane” is the plane perpendicular to the axis of rotation of the tyre which is located halfway between the two beads and passes through the middle of the belt. Rubber is considered any type of elastomer, whether it is of the diene type or of the nondiene type, for example a thermoplastic.

The term “layer” is used to describe a sheet, strip or any other element of relatively small thickness compared to its other dimensions, preferably having a ratio of the thickness to the largest of the other dimensions that is less than 0.5, more preferably less at 0.1.

The term “yarn bundle” is used to describe multiple filaments that are grouped together. The filaments are also called filament fibres and are long continuous fibres, that are typically created by spinning process. The filaments in the yam bundle may be slightly twisted in a Z-direction or S-direction or may be untwisted.

The yarn bundle preferably is configured as single yarn. Such a yarn is also called singly- ply or one-ply yarn. This means that the filaments of the yarn bundle are held together with a small amount of twist in the same direction for all filaments making up the yarn bundle. This also means in other words that the yarn bundle is not generated by plying.

Plying is the process of twisting plies together to create a stronger yam. The plies (also called strands) - i.e. groups of filaments that are held together with a small amount of twist - are twisted together in the direction opposite that in which they were spun. In contrast to a single yarn - which is not generated by plying - in a two-ply yam, the yarn consists of a first group of filaments held together with a small amount of twist and a second group of filaments held together with a small amount of twist, and the two groups are then intertwined by plying.

With regard to the second and third layer - i.e. the working ply - and according to a preferred embodiment of the invention, the second and the third reinforcements are single monofilaments or the second and third reinforcements are twisted monofilaments. It is possible to use twisted monofilaments as the second and third reinforcement. Twisted monofilaments are structures comprising two or more monofilaments that are twisted together. Alternatively, it is also possible to use single monofilaments as second and third reinforcement. Particular when using single monofilaments, the thickness of the rubber above and below the reinforcements embedded in the rubber can be kept constant, even though the thicknesses of the working plies - i.e. the thicknesses of the second and third layer - are reduced. Hence, the durability of the tyre is not negatively affected, even though a thinner belt is used.

With regard to the first layer and as already mentioned, the assemblies of yarn bundles comprise at least two yam bundles. Preferably the assemblies comprise more than two yam bundles, for example three yarn bundles, four yarn bundles or five yarn bundles.

According to a preferred embodiment of the invention the assemblies of yarn bundles are untwisted assemblies. Instead, for each assembly the yam bundles within the assembly preferably extend parallel to each other. This helps to maintain the durability of the tyre even the amount or rubber within the first layer is reduced.

In this context and according to another preferred embodiment of the invention, all yam bundles in each assembly are arranged side by side to each other. In other words, this means that the yam bundles are arranged in a row next to each other. This is particularly preferred in cases where the assemblies comprise more than two yarn bundles. Except for the outermost yam bundles of one assembly or except in cases where the assembly only comprises two yarn bundles, each yarn bundle in one assembly has two contact points to another yam bundle.

According to another preferred embodiment of the invention, a width of the assembly of yam bundles is at least 0.2 mm, preferably at least 0.4 mm and further preferably at least 0.5 mm. In this regard and according to another preferred embodiment of the invention the width of the assembly of yam bundles is not more than 1.5 mm, preferably not more than 1.1 mm, further preferably not more than 0.8 mm. The width of the assembly is preferably the greatest distance across one assembly of yam bundles. For example, for an assembly comprising two yarn bundles the width of the assembly preferably corresponds to the sum of the diameters of the two yarn bundles. As the yarn bundles in one assembly are preferably arranged side by side to each other, the width of the assembly preferably correspond to the sum of the diameters of all the yam bundles in the assembly. In relation to this and according to another preferred embodiment of the invention, the diameter of the yarn bundle is preferably at least 0.1 mm, and preferably at least 0.2 mm. Furthermore, the diameter of the yarn bundle is preferably not more than 0.6 mm, preferably not more than 0.5 mm and further preferably not more than 0.4 mm.

The diameter of the yam bundle is further preferably below 0.5 mm and further preferably below 0.4 mm. The diameter can for example be 0.46 mm, 0.37 mm or even as low as 0.26 mm. It was found that using yam bundles with such diameters provide in the assembly of yam bundles highly durable tyres despite the thin belt. Further preferably it is possible that the yarn bundles do not all have the same diameter, but instead that the yarn bundles have different diameters. However, it is preferred that all yam bundles have the same diameter.

With regard to a diameter of the second or third reinforcement - i.e the single monofilament - it is preferred that the diameter is preferably 0.15 mm to 0.35 mm and further preferably 0.2 mm to 0.3 mm. Using such diameters makes it possible to reduce the thickness of the belt even further.

Further preferably as already mentioned the individual assemblies are preferably spaced apart from each other. In this regard and according to another preferred embodiment of the invention, the assemblies of yam bundles are spaced apart from each other with a distance of at least 0.1 mm, preferably at least 0.15 mm and further preferably at least 0.2 mm. It was found that a distance below 0.1 mm may affect the durability of the tyre negatively. Without being bound to a specific theory it is believed that the distance of at least 0.1 mm helps to absorb shearing forces and thus helps to increase the durability of the tyre.

Further preferably the assemblies of yam bundles are spaced apart from each other with a distance being not more than 1 mm, preferably not more than 0.35 mm and further preferably not more than 0.25 mm. Providing more space in between the individual assemblies may affect the durability of the tyre and the rolling resistance negatively.

Particularly preferably a tyre is provided, wherein the assemblies of yarn bundles are spaced apart from each other with a distance of 0.1 mm to 1 mm, preferably 0.15 mm to 0.35 mm, and even more preferably 0.2 mm to 0.25 mm. It has been found that such values allow to maintain the durability of the tyre and to decrease the amount or rubber in the belt.

It was also found that a ratio between the width of the assemblies of yarn bundles and the distance between the assemblies affects the durability and the rolling resistance of the tyre. In particular, the ratio of the width of the assembly to the distance is preferably at least 1.8/1, further preferably at least 1.85/1, also further preferably at least 2.3/1, and particularly preferably at least 2.7/1. It was also found that there is a preferred upper limit for the ratio of the width to the distance, which is preferably not more than 5/1, further preferably not more than 3.5/1. A further preferred upper limit for the ratio of the width to the distance is 3.3/1.

According to another preferred embodiment of the invention, a thickness of the first layer is below 1 mm. In this context a thickness of the first layer means the thickness of the first layer in radial direction. Preferably the thickness is even below 0.9 mm and further preferably below 0.8 mm. For example, the thickness of the first layer is 0.7 mm, or 0.7 mm ± 0.08 mm. Despite the small thickness of the first layer the assemblies of yarn bundles ensure a high durability of the tyre.

Further preferably, a thickness of the second or third layer is below 1 mm. Preferably the thickness is even below 0.9 mm. For example, the thickness of the second or third layer is 0.8 mm or 0.7 mm. The second and third layer can have the same thickness or can have different a thickness. Despite the small thickness of the second and third layer, the second and third layers still ensure a high durability of the tyre.

Thus, with regard to the overall thickness of the belt - i.e. the sum of the thicknesses of the first, the second and the third layer - preferably a belt is provided having a thickness of below 2.8 mm, further preferably below 2.6 mm, more preferably below 2.5 mm and even more preferably below 2.45 mm. For example, the thickness of the belt is 2.3 mm, 2.1 mm, or 2.0 mm.

With regard to the material of the reinforcements, the second and third reinforcements are preferably made of metal, preferably steel. Preferably the steel is a carbon steel however it is also possible to use other steels, for example stainless steels, or other alloys. Particularly preferably the second and/or third reinforcements are free of a sheath, and in particularly free of a sheath of a polymer material such as a thermoplastic. Further preferably the second and third reinforcements consist of metal.

With regard to the first reinforcements, these comprise a heat shrinkable material. According to a preferred embodiment of the invention, the heat shrinkable material is selected from the group consisting of polyamides, polyesters, polyketons, and mixtures thereof.

Preferred polyamides are polyamides 4-6, 4-10, 5-6, 6, 6-6, 11 or 12. Preferred polyesters are PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PEF (polyethylene furanoate or also called polyethylene furan-2,5-dicarboxylate), PBT (polybutylene terephthalate), PBN (polybutylene naphthalate), PPT (polypropylene terephthalate), PPN (polypropylene naphthalate).

Particularly preferably the heat-shrinkable material is a polyamide, preferably a linear aliphatic polyamide, and further preferably PA 6-6, or the heat-shrinkable material is a polyester.

With regard to the rubber, it is further preferred that the rubber of the first layer, the second layer and the third layer is preferably a diene rubber, which is derived at least in part from monomers of dienes. The rubber may comprise further components such as fillers for example carbon black.

Further preferably the diene rubber is selected from the group consisting of polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), butadiene copolymers, isoprene copolymers, and mixtures of these. The copolymers is preferably selected form the group consisting of butadiene- styrene (SBR) copolymers, isoprenebutadiene (BIR) copolymers, isoprene-styrene (SIR) copolymers and isoprenebutadiene- styrene (SBIR).

As already mentioned, the assemblies of yam bundles comprise at least two yam bundles, preferably more than two yam bundles. In this context and according to another preferred embodiment of the invention, the assemblies of yarn bundles comprise not more than seven yam bundles per assembly. It is believed that assemblies with a higher number of yarn bundles per assembly may negatively affect the durability of the tyre.

With regard to the number of yarn bundles per assembly and according to another preferred embodiment of the invention, the number of yam bundles in the assemblies is the same for all assemblies. In an alternative preferred embodiment, the number of yam bundles in the assemblies is not the same for all assemblies.

In particular in case the number of yarn bundles in the assemblies is not the same for all assemblies, it is preferred that a repetitive pattern with regard to the number of yarn bundles is formed in axial direction over the belt. For example, the first assembly may comprise two yam bundles, the second assembly being neighboring to the first assembly may comprise three yarn bundles, the third assembly being neighboring to the second assembly may comprise again two yam bundles, and so on forming a pattern with the repeating unit 2-3. Also, other patterns are possible such as 2-2-3-3, 4-2-2, or 7-2-5. The repeating unit does preferably not comprise more than eight designations about the number of yarn bundles per assembly. For illustration, the repeating unit 2-3 has two designations, the repeating unit 2 -2-3-3 has four designations, while the repeating unit 7- 2-5 has three designations. Further preferably the repeating unit does not comprise more than 30 individual yarn bundles. For illustration, the repeating unit 2-3 has five - i.e. the sum of two and three - individual yam bundles, the repeating unit 2-2-3-3 has 10 individual yam bundles, while the repeating unit 7-2-5 has 14 individual yarn bundles.

Further preferably in case the number of yam bundles in the assemblies is not the same for all assemblies, it is preferred that the number of yam bundles in the assemblies increase with an increasing distance of the assembly from the median circumferential plane of the tyre. This makes it possible to increase the strength on the edges of the belt. Preferably with regard to the axial direction over the belt the first assembly, the first two assemblies, the first three assemblies, the first four assemblies, or the first five assemblies have a higher number of yarn bundles per assembly than the further assemblies and/or the last five assemblies, the last four assemblies, the last three assemblies, the last two assemblies or the last assembly has a higher number of yam bundles per assembly than the preceding assemblies. Further preferably with regard to the axial direction over the belt the first percent of assemblies, the first two percent of assemblies, the first three percent of assemblies, or the first four percent of assemblies have a higher number of yam bundles per assembly than the further assemblies and/or the last four percent of assemblies, the last three percent of assemblies, the last two percent of assemblies and the last percent of assembly has a higher number of yam bundles per assembly than the preceding assemblies; wherein all assemblies in the first layer constitute 100 percent. Having a higher number of yam bundles in the assemblies that are located on the edge of the belt may also make it possible reduce an overall number of layers that may be used on the edge of the belt.

According to another preferred embodiment of the invention the yarn bundles of the first reinforcement are warp filaments of a woven fabric being embedded in the first layer, and wherein the assemblies of yam bundles are formed by at least two neighboring warp filaments arranged side by side to each other. Further preferably the minimum distance between the individual assemblies matches a diameter of a weft filament of the woven fabric.

In this regard and according to another preferred embodiment of the invention the weft filament of the woven fabric altematingly passes over and under neighboring assemblies.

With regard to the further structure of the tyre and according to another preferred embodiment of the invention, a tyre is provided wherein the tyre further comprises a crown surmounted by a tread, two sidewalls, and two beads, wherein each sidewall connects one bead to the crown, wherein the tyre further comprises a carcass reinforcement anchored in each of the beads and extending in the sidewalls up towards the crown, and wherein the belt is located radially between the carcass reinforcement and the tread.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example and with reference to the accompanying drawings in which: Fig. 1 is a schematic view of a tyre according to a preferred embodiment of the invention;

Fig. 2 is a schematic view of a belt of the tyre of figure 1;

Fig. 3 is a schematic view another belt according to a further preferred embodiment of the invention;

Fig. 4 is a schematic view of another belt according to a further preferred embodiment of the invention;

Fig. 5 is a schematic view of a comparative belt; and

Fig. 6 is another schematic view of a comparative belt.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so as to assist those having ordinary skill in the art in a comprehensive understanding of the invention, and the present invention is not limited to the embodiments disclosed below. Referring to the drawings, wherein like reference signs designate like or corresponding parts throughout the several views.

Figures 1 shows a schematic view of a tyre 10 according to an embodiment of the invention. The tyre 10 is a radial tyre, defining three main directions, circumferential (X), axial (Y) and radial (Z). The tyre 10 comprises a crown 12 surmounted by a tread 14, two sidewalls 16, two beads 18, each sidewall 16 connecting each bead 18 to the crown 12, a carcass reinforcement 20 anchored in each of the beads 18 and extending in the sidewalls 16 up to the crown 12. The tyre 10 further comprises a belt 22 extending in the crown 12 in the circumferential direction (X) and located radially between the carcass reinforcement 20 and the tread 14.

Figure 2 shows a schematic view of the belt 10 of the tyre of figure 1. The belt of this specific embodiment comprises three superposed layers 24, 26, 28, each layer comprising reinforcements 30, 32, 34 being embedded in a rubber. A first layer 24 is arranged on a tread side of the tyre 10 and comprises first reinforcements 30 comprising a heat shrinkable material. A second layer 26 is in contact with the first layer 24 and arranged under the first layer 24. The second layer 26 comprises second reinforcements 32

RECTIFIED SHEET (RULE 91) ISA/EP comprising metal. A third layer 28 is in contact with the second layer 26 and arranged under the second layer 26 and comprises third reinforcements 34 comprising metal.

As can be seen in figure 2, the second and third reinforcements 32, 34 are single monofilaments 32a, 34a. On the other hand the first reinforcements 30 are assemblies 30 of yarn bundles 36, each yarn bundle 36 comprising multiple filaments (the multiple filaments are not illustrated in the figure), and wherein each assembly 30 comprises at least two yarn bundles 36. In this specific embodiment the assembly 30 comprises two yarn bundles 36. Within one assembly 30 the yarn bundles 36 are not spaced apart from each other but are directly adjacent to each other. The induvial assemblies 30 on the other hand are spaced apart from each other with a distance 38.

In this particular embodiment the distance 38 is 0.3 mm. Furthermore, a width 40 of the assembly 30 is 0.75 mm. The width 40 of the assembly 30 is the greatest distance across one assembly 30. As in this case the assemblies 30 comprise two yam bundles 36 and the yarn bundles 36 have a circular cross-section, the width 40 of the assembly 30 corresponds to the sum of a diameter 42 of the yarn bundle 36, the diameter is for this embodiment 0.375 mm.

As is also evident from figure 2, the yam bundles 36 in the assemblies 30 are not twisted with each other. Instead, they run parallel to each other. Furthermore, they extend circumferentially around the tyre 10 casing in an angle of 0 degree ± 5 degrees with the median circumferential plane M.

With regard to a diameter 44 of the second reinforcement 32 - i.e the single monofilament 32a - or a diameter 46 of the third reinforcement 34 - i.e the single monofilament 34a -, in this embodiment the diameter 44, 46 is the same for both single monofilaments 32a, 34a, and is 0.3 mm. Furthermore, in this embodiment a thickness 48 of the first layer 24 is below 1 mm, namely 0.7 mm. A thickness 50 of the second layer 26 is 0.7 mm and a thickness 52 of the third layer 28 is also 0.7 mm. Thus, in this particular embodiment an overall thickness of the belt is 2.1 mm.

Also indicated in figure 2 is a spacing 54 between the assemblies 30 of the first layer 24. As in this embodiment all assemblies 30 comprise the same number of yarn bundles 36, the spacing 54 is equal to the sum of the width 40 and the distance 38. In this embodiment the spacing 54 is 1.05 mm.

For the second layer, a spacing 56 of the second reinforcement 32 is in this embodiment 0.71 mm and for the third layer a spacing 58 of the third reinforcement 34 is in this embodiment also 0.71 mm.

Figure 3 shows a schematic view of a further belt 10 according to another preferred embodiment of the invention. The general structure of the belt 22 is the same as in figure 2 - i.e. the belt 22 comprises three superposed layers 24, 26, 28, each layer comprising reinforcements 30, 32, 34 being embedded in a rubber. In the following only the differences are described:

In the embodiment in figure 3 compared to figure 2, the first reinforcement 30 are assemblies 30 comprising three yam bundles 36, instead of two yam bundles 36.

Furthermore, in this embodiment the distance 38 between two assemblies 30 is 0.3 mm, and the width 40 of the assembly 30 is 0.81 mm. The diameter 42 of the yam bundle 36 is in this example 0.27 mm

With regard to the diameter 44 of the second and third reinforcement 32, 34, the diameter 44 of the single monofilament 32a and the diameter 46 of the single monofilament 34a, are in this embodiment again the same, namely 0.3 mm.

Furthermore, in this embodiment the thickness 48 of the first layer 24 is 0.6 mm. The thickness 50 of the second layer 26 is 0.7 mm and the thickness 52 of the third layer 28 is also 0.7 mm. Thus, in this particul ar embodiment the overall thickness of the belt 22 is 2.0 mm. The spacing 54 between the assemblies 30 of the first layer 24 is in this embodiment 1.11. mm. The spacing 56 of the second reinforcement 32 is in this embodiment 0.71 mm and the spacing 58 of the third reinforcement 34 is in this embodiment also 0.71 mm.

Figure 4 shows a schematic view of another belt 22 according to another preferred embodiment of the invention. The general structure of the belt 22 is again the same as in figure 2 and 3 - i.e. the belt 22 comprises three superposed layers 24, 26, 28, each layer comprising reinforcements 30, 32, 34 being embedded in a rubber. While in figure 3 compared to figure 2 the structure of the working ply - i.e. the layers 26, 28 was the same as in figure 2 and the structure of the cap ply - i.e. the first belt 24 was different, for the embodiment in figure 4, the situation is inverted:

In the embodiment in figure 4 compared to figure 2, the second and third reinforcement 32, 34 are not single monofilaments. Instead, they are twisted monofilaments 32b, 34b, meaning that each second or third reinforcement consists of two single monofilaments twisted together. The first layer 24 is on the other hand the same structure as in figure 2, with two yarn bundles 36 forming an assembly 30 as first reinforcement 30.

A diameter of the single monofilament forming up the twisted monofilament 32b as well as a diameter of the single monofilament forming up the twisted monofilament 34b, are in the embodiment in figure 0.2 mm. Thus, the overall diameter 44, 46 of the second and third reinforcement - i.e. the twisted monofilament is 0.4 mm. The spacing 56 of the second reinforcement 32 is in this embodiment 0.704 mm and the spacing 58 of the third reinforcement 34 is in this embodiment also 0.704 mm.

Furthermore, in this embodiment in figure 4 the thickness 50 of the second layer 26 is 0.8 mm and the thickness 52 of the third layer 28 is also 0.8 mm. As the thickness 48 of the first layer 24 is 0.9 mm, the overall thickness of the belt 22 in this particular embodiment is 2.5 mm.

EXAMPLES

Examples of the present invention will be described below, but the present invention is not limited to the following example.

In this example, a finite element analysis (FEA) is carried out to illustrate the advantages of the invention in terms of rolling resistance:

The FEA was carried out for the structure as shown in figure 2 with two different set of values for the parameters of the first layer 24, i.e. for the layer thickness 48, the diameter 42, the assembly width 40 and the distance 38. A further FEA was carried out for the structure as shown in figure 3 and a further FEA was carried out for the structure as shown in figure 4.

As comparison a further FEA was carried out for a structure as shown in figure 5, where the first reinforcements 30’ are not configured as assemblies of at least two yarn bundles 36’. Instead, the reinforcements 30’ consist of the yarn bundle 36’. Furthermore, in figure 5, the working plies 26’, 28’ comprise twisted monofilaments 32b’, 34b’. As further comparison a FEA was carried out for the structure as shown in figure 6, where the first reinforcements 30’ are not configured as assemblies of at least two yarn bundles 36’. Instead, the reinforcements 30’ consist of the yarn bundle 36’. Furthermore, in figure 6, the working plies 26’, 28’ comprise single monofilaments 32a’, 34a’. All reference numerals for the prior art structure shown in figure 5 and 6 are denoted with a prime (‘).

For all the FEAs, where the working plies - i.e. layers 26 and 28 - are configured such that the second and third reinforcements 32, 34 are single monofilaments 32a, 34a, a steel belt according to 135 epdm 1* 0.3 was used for the FEA. “epdm” means “ends per decimetre” which is a measure of the density of the reinforcements 32, 34. The values after the epdm indicate that it is a monofilament (1), where the diameter 44, 46 of the monofilament is 0.3 mm. Thus, the use of the above indicated steel belt results in the parameters given in table 1 for the diameter 44, 46 and the spacing 56, 58.

For the FEAs, where the working plies - i.e. layers 26 and 28 - are configured such that the second and third reinforcements 32, 34 are twisted monofilaments 32b, 34b, a steel belt according to 95 epdm 2* 0.3 and according to 142 epdm 2*0.20 was used for the FEA, resulting in the parameters given in table 1 for the diameter 44, 46, of the first and second reinforcement and the spacing 56, 58.

For the cap ply - i.e. the layer 24 - different nylon fabric according to the specifications indicated in table 2 where used for the FEA, resulting in the parameters given in table 1 for the spacing 54 and the distance 38. The diameter 42 and the assembly width 40 were estimated based on the type of nylon fabric. A fabric according to 66 epdm 2*2800/1 for example means that density of assemblies 30 is 66 per 1 dm, that the assembly 30 consists of two (2) yarn bundles 36, and that one yam bundle 36 is a single yarn (/I) having a linear density of 2800 dtex. Dtex is the gram weight of the 10000 meters of length of the yarn.

Table 1 summarizes the values of the parameters used for the FEA.

Table 3 lists the resulting rolling resistance from the FEA.

As can be seen by comparing parameters for the FEA #4 with the parameters for the FEA #C1 (table 1 und table 2), even though the percentage of nylon in the cap ply 24 increases from 100 % to 189 % the layer thickness 48 of the cap ply 24 only increases from 100 % (0.8 mm) to 115 % (0.92 mm), despite the fact that for the FEA #4 for the first reinforcement 30 a yam bundle 36 with a higher diameter 42 was used compared to #C1. The overall belt thickness decreases from 2.8 mm to 2.52 mm. The effect of the different belt structure for the rolling resistance (see table 3) is evident for the significant decrease from 12.3 N/kN to 12.11 N/kN.

With regard to the parameters for the FEA #1 and the FEA #2, where the FEA #1 has the same cap ply 24 construction as the FEA #4, it is evident that the thickness 48 of the cap ply 24 can be reduced from 100% (0.92 mm) to around 78% (0.72 mm) and still achieving a nylon content of 95% that is very comparable to the nylon content of the structure for FEA #C1. Despite the comparable Nylon content, the thickness 48 of the cap ply 24 is in the FEA #C1 (0.80 mm) is much higher than in the FEA #2 (0.72 mm). The results of the FEA #1 and #2 further show that reducing the thickness 48 from the cap ply 24 decreases the rolling resistance from 12.02 N/kN to 11.86 N/kN.

As can further be seen, by comparing the FEA #1, #2, and 3# to the FEA #C2, where for all FEAs the structure of the working plies 26, 28 with monofilaments 32a, 34a is the same, is that the rolling resistance for the FEA #2 gives a better rolling resistance than the comparative example #C2, while the FEA #3 gives nearly comparable results as #C2. Furthermore, the results also show that having a diameter 42 of the yarn bundle 36 below 0.5 mm, having the assemblies 30 of yarn bundles 36 spaced apart from each other with a distance 38 of 0.2 mm to 0.3 mm and having a thickness 48 of the first layer 24 below 0.9 mm leads to a better rolling resistance.

REFERENCE SIGNS

10 tyre

12 crown

14 tread

16 sidewall

18 bead

20 carcass reinforcement

22 belt

24 first layer, cap ply

26 second layer, working ply

28 third layer, working ply

30 first reinforcement, assembly

32a second reinforcement, single monofilament

32b second reinforcement, twisted monofilament

34a third reinforcement, single monofilament

34b third reinforcement, twisted monofilament

36 yarn bundle

38 distance between assemblies

40 width of assembly

42 diameter of yam bundle

44 diameter of second reinforcement

46 diameter of third reinforcement

48 thickness of first layer

50 thickness of second layer

52 thickness of third layer

54 spacing in first layer

56 spacing in second layer

58 spacing in third layer

X circumferential direction

Y axial direction

Z radial direction

M circumferential plane

Claims

1. Tyre (10) for a vehicle, the tyre (10) comprising a belt (22), wherein the belt (22) comprises a multilayer composite laminate comprising at least three superposed layers (24, 26, 28), each layer (24, 26, 28) comprising reinforcements (30, 32, 34) being embedded in a rubber, wherein a first layer (24) is arranged on a tread side of the tyre (10) and comprises first reinforcements (30) comprising a heat shrinkable material, wherein a second layer (26) is in contact with the first layer (24) and arranged under the first layer (24), wherein the second layer (26) comprises second reinforcements (26) comprising metal, wherein a third layer (28) is in contact with the second layer (26) and arranged under the second layer (26), wherein the third layer (28) comprises third reinforcements (34) comprising metal, wherein the first reinforcements (30) are assemblies (30) of yarn bundles (36), each yam bundle (36) comprising multiple filaments, and wherein each assembly (30) comprises at least two yam bundles (36).

2. The tyre (30) according to claim 1, wherein the second and the third reinforcements (32, 34) are single monofilaments (32a, 32a); or wherein the second and the third reinforcements (32, 34) are twisted monofilaments (32b, 34b).

3. The tyre (10) according to any of the preceding claims, wherein the yarn bundle (36) is configured as single yarn.

4. The tyre (10) according to any of the preceding claims, wherein the assemblies (30) of yarn bundles (36) are untwisted assemblies.

5. The tyre (10) according to any of the preceding claims, wherein all yarn bundles (36) in each assembly (30) are arranged side by side to each other.

6. The tyre (10) according to any of the preceding claims, wherein a width (40) of the assembly (30) of yarn bundles (36) is at least 0.2 mm, preferably at least

0.4 mm and further preferably at least 0.5 mm and/or wherein a width (40) of the assembly (30) of yam bundles (36) is not more than 1.5 mm, preferably not more than 1.1 mm, further preferably not more than 0.8 mm.

7. The tyre (10) according to any of the preceding claims, wherein a diameter (42) of the yam bundle (36) is at least 0.1 mm, preferably at least 0.2 mm, and/or wherein a diameter (42) of the yarn bundle (36) is not more than 0.6 mm, preferably not more than 0.5 mm and further preferably not more than 0.4 mm.

8. The tyre (10) according to any of the preceding claims, wherein the assemblies (30) of yarn bundles (36) are spaced apart from each other with a distance (38) of at least 0.1 mm, preferably at least 0.15 mm and further preferably at least 0.2 mm and/or wherein the assemblies (30) of yarn bundles (36) are spaced apart from each other with a distance (38) of not more than 1 mm, preferably not more than 0.35 mm and further preferably not more than 0.25 mm.

9. The tyre (10) according to any of the preceding claim, wherein a ratio of a width (40) of the assembly (30) of yarn bundles (36) to a distance (38) between the assemblies (30) of yarn bundles (36) is at least 1.8/1, preferably at least 1.85/1, preferably at least 2.3/1, and further preferably at least 2.7/1, and/or wherein a ratio of a width (40) of the assembly (30) of yarn bundles (36) to a distance (38) between the assemblies (30) of yam bundles (36) is not more than 5/1, further preferably not more than 3.5/1 and preferably not more than 3.3/1.

10. The tyre (10) according to any of the preceding claims, wherein a thickness (48) of the first layer (24) is below 1 mm, preferably below 0.9 mm, and further preferably below 0.8 mm.

11. The tyre (10) according to any of the preceding claims, wherein the heat shrinkable material is selected from the group consisting of polyamides, polyesters, polyketons, and mixtures thereof.

12. The tyre (10) according to any of the preceding claims, wherein the assemblies (30) of yarn bundles (36) comprise not more than seven yarn bundles (36) per assembly (30).

13. The tyre (10) according to any of the preceding claims, wherein the number of yarn bundles (36) in the assembly (30) is the same for all assemblies (30); or wherein the number of yam bundles (36) in the assembly (30) is not the same for all assemblies (30).

14. The tyre (10) according to any of the preceding claims, wherein the number of yarn bundles (36) in the assembly (30) increase with an increasing distance of the assembly (30) from a median circumferential plane (M) of the tyre (10).

15. The tyre (30) according to any of the preceding claims, wherein the yarn bundles (36) of the first reinforcement (30) are warp filaments of a woven fabric being embedded in the first layer (24), and wherein the assemblies (30) of yam bundles (36) are formed by at least two neighboring warp filaments arranged side by side to each other.

16. The tyre (10) according to the preceding claim, wherein a weft filament of the woven fabric altematingly passes over and under neighboring assemblies (30).

17. The tyre (10) according to any of the preceding claims, wherein the tyre (10) further comprises a crown (12) surmounted by a tread (14), two sidewalls (16), and two beads (18), wherein each sidewall (16) connects one bead (18) to the crown (12), wherein the tyre (10) further comprises a carcass reinforcement (20) anchored in each of the beads (18) and extending in the sidewalls (16) up towards the crown (12), and wherein the belt (22) is located radially between the carcass reinforcement (20) and the tread (14).

18. Wheel for a vehicle comprising a tyre rim for being connected to an axle of the vehicle and a tyre (10) according to any of claims 1 to 17 mounted to the tyre rim.