Commercial vehicle tires

Abstract

Commercial vehicle tires of radial construction with a belt (3) of at least three layers, which, viewed from radially inside to radially outside, has at least one locking layer (5) and two working layers (6, 7), wherein the first, radially inner working layer (6) is the widest belt layer and is wider than the second, radially outer working layer (7), and the second, radially outer working layer (7) is at least as wide as the locking layer (5), wherein the working layers (6, 7) contain reinforcing elements, in particular made of steel cord, which in each working layer (6, 7) run parallel to each other and at an angle of 15° to 24° to the circumferential direction of the tire, wherein the reinforcing elements in one working layer (6, 7) cross the reinforcing elements in the other working layer (6, 7), wherein at least the edges of the second, radially outer working layer (7) are each covered by an edge reinforcement strip (9, 9', 9'') which is embedded in rubber.Contains parallel load-bearing elements, . characterized by that the strength carriers of the edge reinforcement strip (9, 9', 9'') are hybrid cords running at an acute angle of 15° to 30° to the circumferential direction, each consisting of at least one high-modulus yarn and one low-modulus yarn, where the force, normalized to the yarn fineness in tex, which must be applied to the high-modulus yarn, is > 300 mN / tex at 1% elongation and > 500 mN / tex at 2% elongation and where the force that must be applied to the low-modulus yarn, normalized to the yarn fineness in tex, is < 150 mN / tex at 1% elongation and < 200 mN / tex at 2% elongation.

Description

[0001] The invention relates to a commercial vehicle tire of radial construction with a belt of at least three layers, which, viewed from radially inside to radially outside, has at least one locking layer and two working layers, wherein the first, radially inner working layer is the widest belt layer and is wider than the second, radially outer working layer, and the second, radially outer working layer is at least as wide as the locking layer, wherein the working layers contain reinforcing elements, in particular made of steel cord, which in each working layer run parallel to each other and at an angle of 15° to 24° to the circumferential direction of the tire, wherein the reinforcing elements in one working layer cross the reinforcing elements in the other working layer, wherein at least the edges of the second, radially outer working layer are each covered by an edge reinforcement strip which contains reinforcing elements embedded in rubber and running parallel to each other.

[0002] Radial tires for commercial vehicles, especially trucks or buses, have a belt with at least two, and in particular a belt with four, layers. In a so-called triangular belt consisting of four layers, the reinforcing elements in the first, radially innermost layer typically form an angle of approximately 45° to 65° with the circumferential direction. In the two working layers, the reinforcing elements run at angles of 15° to 24° to the circumferential direction. The fourth layer, the radially outermost layer, is the so-called protective layer, whose reinforcing elements run circumferentially or at an acute angle to the circumferential direction.

[0003] It is known that the service life of commercial vehicle tires can be affected by the continuous stresses in the area of ​​the belt edges, as the belt ply edges possess a certain degree of mobility. This can lead to cracks in the surrounding rubber material in the belt edge areas and to separation of the belt edges. Attempts have therefore already been made to implement appropriate measures to reduce the mobility of the belt edges, for example, by selecting the spacing of the reinforcing elements in the working layers, by adjusting the belt ply widths and the reinforcing element angles, and by installing shoulder pads or belt edge pads. To further reduce the mobility of the belt edges, it is also known to cover the edge areas of the working layers with a strip of rubberized polyamide cords, for example, PA 6.6 or PA6, running circumferentially around the tire.6 is a low-modulus material with a tensile strength-elongation behavior that is not very favorable for this application. The known nylon strips were therefore unable to influence the mobility of the edges of the working layers to the desired extent.

[0004] A commercial vehicle tire of the type mentioned above is known, for example, from DE 693 05 211 T2. This commercial vehicle tire has a four-ply belt with a barrier layer, a first, radially inner working layer, a second, radially outer working layer, and a protective layer. The radially inner working layer is the widest belt layer. The second, radially outer working layer is as wide as the barrier layer. The working layers contain steel or aramid cords which run at an angle of 17° to 27° to the circumferential direction. The edges of the second, radially outer working layer are each covered by an edge reinforcement strip, which consists of cords of steel, aramid, nylon, polyester, or polyalkylenes embedded in rubber, running parallel to each other and at an angle of 0° to 55° to the circumferential direction (0° to 5° in the exemplary embodiment), with nylon cord being preferred.The edge reinforcement strips reduce stresses in the area of ​​the belt edges by restricting growth in the tire shoulders or by distributing the stresses over a larger area.

[0005] DE 694 03 315 T2 discloses a vehicle tire with a belt and a belt bandage. The belt has two belt layers of equal width made of aramid cords. The belt bandage comprises two outer bandage parts and a central bandage part, which extends over the radially outer belt layer and the two outer bandage parts and terminates at the belt edges of the belt layers. The bandage parts each contain a hybrid cord that runs at an angle of 0° to 3° to the circumferential direction and consists of at least one yarn with a high modulus of elasticity, for example, an aramid fiber, a polyvinyl alcohol fiber, a carbon fiber, or a glass fiber, and at least one yarn with a low modulus of elasticity, for example, an aliphatic polyamide fiber, such as nylon.These hybrid cords are intended to influence the behavior of the vehicle tire during molding in the vulcanization mold in such a way that tire expansion during high-speed driving is reduced, thus providing a lightweight tire with good high-speed durability.

[0006] Furthermore, DE 10 2012 217 332 A1 discloses a run-flat pneumatic tire with crescent-shaped inner rubber layers installed in the sidewall area to absorb the load during run-flat operation. This tire also has a belt with belt layers containing cords inclined to the circumferential direction. Radially outside the belt, a belt cover layer is arranged, which contains a circumferentially oriented cord, in particular a composite cord. The composite cord has two types of organic fibers, one of which has high extensibility and low elasticity, and the other has low extensibility and high elasticity. This is intended to suppress flexing in the tire's zenith area during run-flat operation and to improve run-flat durability, steering stability, and ride comfort.

[0007] Furthermore, it is known to use a hybrid cord as a reinforcing material in a reinforcement layer of a pneumatic tire, in particular the carcass layer or a belt ply. For example, DE 10 2011 053 264 A1 discloses a hybrid cord which has, for instance, the construction Aramid 1670 × 2 + PA 6.6 1400 × 1. DE 10 2009 026 205 A1 discloses a reinforcing cord for the carcass layer of pneumatic tires, which consists of two yarns of non-metallic material twisted together. The reinforcing cord is a hybrid cord, one yarn of which is made of polyketone and the other of which is made of polyester or rayon. The use of this reinforcing cord in the carcass layer of a pneumatic tire is intended to improve the tire's durability.The hybrid cord known from DE 10 2008 037 615 A1 is intended for use as a reinforcing material in the belt band of a passenger car tire and consists of two twisted yarns, one of which is made of aramid and the other of polyamide, in particular nylon. Both yarns are initially twisted in the same direction, while the hybrid cord is twisted in the opposite direction. The use of this hybrid cord in the belt band is intended to significantly improve the tire's high-speed performance.

[0008] The demands placed on the service life and durability of commercial vehicle tires have increased, making it necessary to better prevent the occurrence of separation and cracking at the belt edges. The object of the present invention is therefore to find a method for significantly improving the circumferential stiffness at the belt edge areas, thereby suppressing or noticeably reducing stress at the belt edges. High circumferential stiffness also significantly reduces the mobility of the belt edges, thus extending the service life of the tire.

[0009] The problem set out in the invention is solved by the fact that the reinforcing elements of the edge reinforcement strip (9, 9', 9'') are hybrid cords running at an acute angle of 15° to 30° to the circumferential direction, each consisting of at least one high-modulus yarn and one low-modulus yarn, where the force, normalized to the yarn fineness in tex, which must be applied to the high-modulus yarn, is > 300 mN / tex at 1% elongation and > 500 mN / tex at 2% elongation and where the force that must be applied to the low-modulus yarn, normalized to the yarn fineness in tex, is < 150 mN / tex at 1% elongation and < 200 mN / tex at 2% elongation.

[0010] The term "high-modulus yarn" refers to a yarn made from a high-modulus material, while "low-modulus yarn" refers to a yarn made from a low-modulus material. High-modulus and low-modulus yarns are defined by the values ​​in mN / tex given in Table 1 below. The force required to apply to a yarn at 1% elongation and at 2% elongation, normalized to the yarn count in tex, is determined according to ASTM D885. Table 1 yarn 1% elongation 2% elongation Low modulus < 150 mN / tex < 200 mN / tex High modulus > 300 mN / tex > 500 mN / tex

[0011] The hybrid cord, through the combination of at least one high-modulus yarn with one low-modulus yarn, exhibits a very favorable tensile-elongation behavior for its intended use in reinforcement strips at belt edges. The hybrid cord possesses the required elongation capacity for molding the tire into the vulcanization mold with minimal force, but exhibits only slight elongation above approximately 3%. Therefore, in the finished vulcanized tire, the hybrid cord ensures high circumferential stiffness at the belt edges during operation and effectively prevents undesirable movement in the belt edge areas.

[0012] Edge reinforcement strips, in which the hybrid cords run in the circumferential direction of the tire, can exhibit a particularly high circumferential stiffness that is advantageous under high loads.

[0013] In a preferred embodiment of the invention, the edge reinforcement strip covers the edge of the second, radially outer working layer with an overlap width of at least 10 mm on this working layer. The second, radially outer working layer is the one that is subjected to particular stresses at its edges during tire operation. The overlap with the edge reinforcement strip according to the invention is particularly important in this working layer. In one embodiment of the invention, the edge reinforcement strip may cover only the edge of the second, radially outer working layer, in which case the edge reinforcement strip extends along the first, radially inner working layer at most to the edge of this working layer.

[0014] A particularly advantageous embodiment of the invention is one in which the edge reinforcement strip covers the edges of both working layers. In this embodiment, the edges of those belt layers that are typically particularly susceptible to delamination and tearing in the surrounding rubber material are protected from undesirable movement.

[0015] In a further embodiment of the invention, the edge reinforcement strip covers the edges of the two working layers and a fourth belt layer, its overlap width on the fourth belt layer being at least 10 mm and preferably up to 15 mm. This arrangement of the edge reinforcement strips is particularly advantageous for commercial vehicle tires, which are subjected to especially high loads.

[0016] For the intended use of hybrid cords as reinforcing elements in edge reinforcement strips according to the invention, certain materials are particularly advantageous for the filaments of the yarns used. It is especially beneficial if the high-modulus yarn in the hybrid cord consists of filaments made of aramid, glass, or carbon, and if the low-modulus yarn in the hybrid cord consists of filaments made of polyamide, particularly PA 6.6 or PA 6, or of PET. In this context, it is also advantageous if the high-modulus yarn has a fineness of 1500 dtex to 1800 dtex, particularly 1600 dtex to 1700 dtex, and the low-modulus yarn has a fineness of 1200 dtex to 1600 dtex, particularly 1350 dtex to 1450 dtex.

[0017] Depending on the intended use or arrangement of the edge reinforcement strips, it may also be advantageous if, optionally, the inclination of the hybrid cords relative to the circumferential direction corresponds to the inclination of the reinforcing elements in the radially outer working position.

[0018] Further features, advantages, and details of the invention will now be described in more detail with reference to the drawing, which schematically illustrates exemplary embodiments. The drawing shows

[0019] Fig. 1 to Fig. 3 partial cross-sections through each half of a commercial vehicle tire in the area of ​​the belt and the tread, each with an embodiment of the invention.

[0020] Fig. 1 to Fig.Figure 3 schematically shows a cross-section through one half of the tread and belt area of ​​a commercial vehicle tire of a typical standard construction with a radial carcass 1, in particular of a typical construction, an airtight inner layer 2, a four-ply belt 3 and a profiled tread 4. The other components of the tire, such as the sidewalls, the components of bead areas and any shoulder pads or belt edge pads provided at the edge areas of the belt 3, are not shown.

[0021] In the illustrated embodiments, the belt 3 has four belt layers 5, 6, 7, and 8, the radially innermost belt layer being designated as the first belt layer and representing the so-called barrier layer 5. The second and third belt layers are the so-called working layers 6 and 7, with working layer 6 being the widest belt layer. Working layer 7 is slightly wider or essentially the same width as barrier layer 5. The fourth belt layer is the so-called protective layer 8 and has the narrowest width of all belt layers. However, protective layer 8 can also be the same width as the third belt layer, working layer 7. All belt layers 5, 6, 7, and 8 consist, in a known manner, of reinforcing elements embedded in a belt rubber, in particular of steel cord of a known construction.The depicted belt 3 is a so-called triangular belt, in which the reinforcing elements in the barrier position 5 form an angle of approximately 50° to 65° with the circumferential direction. The reinforcing elements in the working positions 6 and 7 typically form an angle of between 15° and 24° with the circumferential direction and run intersecting with each other; the reinforcing elements in the protective position 8 usually run at an acute angle of 15° to 50° to the circumferential direction, but can also be oriented circumferentially.

[0022] According to the invention, at least one edge reinforcement strip 9, 9', 9'', the design and arrangement of which are described in more detail below, is provided at the belt edge areas. Fig.In the embodiment shown in Figure 1, the edge reinforcement strip 9 is designed to be wide enough to cover the edge edges of the two working layers 6, 7 and the protective layer 8. The overlap width b on the protective layer 8, the distance between the edge of the protective layer 8 and the end of the edge reinforcement strip 9, is 10 mm to 15 mm. The edge reinforcement strip 9 projects beyond the radially inner working layer 6 by an overlap width b' of 5 mm to 15 mm.

[0023] At the in Fig. In the embodiment shown in Figure 2, the edge reinforcement strip 9' covers the edges of the working layers 6 and 7, the radially outer working layer 7 with an overlap width b'' of at least 10 mm and preferably up to 15 mm, wherein the edge reinforcement strip 9' extends at most to the edge of the protective layer 8. The edge reinforcement strip 9' projects laterally beyond the inner working layer 6 by the aforementioned overlap width b' ( Fig.1), which can range from 5 mm to 15 mm. In the case of the Fig. In the embodiment shown in Figure 3, the edge reinforcement strip 9' covers only the edge of the radially outer working layer 7 with an overlap width b'' on the working layer 7 of at least 10 mm and preferably up to 15 mm. On the working layer 6, the edge reinforcement strip 9' extends at most to the edge of the working layer 6.

[0024] The edge reinforcement strips 9, 9' and 9'' contain as a reinforcing element a hybrid cord consisting of at least one high-modulus yarn, preferably two high-modulus yarns, and one low-modulus yarn, all yarns being filament yarns. The high-modulus yarn consists in particular of filaments made of aramid, glass, or carbon, and the low-modulus yarn consists in particular of filaments made of polyamide, preferably PA 6.6 or PA 6, or of PET (polyethylene terephthalate). Table 1 above defines what is meant by a high-modulus yarn and a low-modulus yarn.

[0025] Particularly preferred within the scope of the invention is the combination of two aramid yarns with a PA 6.6 (nylon) yarn. The hybrid cord therefore consists in particular of two twisted high-modulus yarns, especially of aramid, wherein the two twisted yarns are twisted with a low-modulus yarn, especially of nylon. The high-modulus yarns have a fineness of 1500 dtex to 1800 dtex, in particular 1600 dtex to 1700 dtex, and the low-modulus yarn has a fineness of 1200 dtex to 1600 dtex, in particular 1350 dtex to 1450 dtex. The yarns and also the hybrid cord are twisted in particular at 200 T / m to 400 T / m, preferably at 250 T / m to 350 T / m. The yarns can be Z-twisted and the hybrid cord S-twisted, or the yarns can be S-twisted and the hybrid cord Z-twisted.

[0026] Regarding the tensile strength-elongation behavior of the hybrid cord, it is advantageous if the force, normalized to the yarn fineness in tex, which must be applied to the hybrid cord at a certain elongation, is 3 cN / tex to 7 cN / tex, in particular 4 cN / tex to 6 cN / tex, at 1% elongation; 10 cN / tex to 20 cN / tex, in particular 13 to 16 cN / tex, at 3% elongation; and 30 cN / tex to 80 cN / tex, in particular 45 cN / tex to 65 cN / tex, at 6% elongation.

[0027] In a preferred embodiment of the invention, the hybrid cord runs in the edge reinforcement strips 9, 9', 9'' in the circumferential direction of the tire. In the production of such edge reinforcement strips 9, 9' and 9'', for example, a strip of hybrid cords embedded in a rubber compound, running parallel to each other and in the longitudinal direction of the strip, is wound circumferentially at the belt edges, according to the respective embodiment. A strip with a width of, for example, 10 mm typically contains between five and fifteen hybrid cords. The winding is carried out in such a way that the turns required, depending on the width of the edge reinforcement strip 9, 9', 9'', are butt-jointed.In another embodiment, a strip of material consisting of a rubber compound with embedded parallel hybrid cords can already be produced in the width required for the edge reinforcement strips 9, 9' and 9'' and laid around the circumference of the raw tire in the area of ​​the belt edges during tire construction.

[0028] In a further embodiment of the invention, a number of hybrid cords are calendered in a parallel arrangement and embedded in a rubber compound. The calendered material is cut obliquely into a strip, such that the hybrid cords in the strip run at an acute angle of, for example, 15° to 30° to the longitudinal direction of the tire. The width of the cut strip corresponds to the respective width of the edge reinforcement strips 9, 9', or 9'', depending on the embodiment. During tire assembly, the strip is positioned accordingly on the belt edge(s), preferably such that the orientation of the hybrid cords with respect to the circumferential direction of the tire coincides with that of the reinforcement strips in the radially outer working position 7.

[0029] The invention is not limited to the embodiments shown. The belt of the commercial vehicle tire can also comprise only three belt layers – one protective layer and two working layers – or more than four belt layers, wherein two of these belt layers are the working layers. Reference number list 1 radial carcass 2 inner layer 3 belts 4 treads 5 Blocking position 6 Working situation 7 Working situation 8 Protective position 9, 9', 9'' edge reinforcement strips b, b', b'' Coverage width

Claims

[1] Commercial vehicle tires of radial construction with a belt (3) of at least three layers, which, viewed from radially inside to radially outside, has at least one locking layer (5) and two working layers (6, 7), wherein the first, radially inner working layer (6) is the widest belt layer and is wider than the second, radially outer working layer (7) and the second, radially outer working layer (7) is at least as wide as the locking layer (5), wherein the working layers (6, 7) contain reinforcing elements, in particular made of steel cord, which in each working layer (6, 7) run parallel to each other and at an angle of 15° to 24° to the circumferential direction of the tire, wherein the reinforcing elements in one working layer (6, 7) cross the reinforcing elements in the other working layer (6, 7), wherein at least the edges of the second, radially outer working layer (7) are each covered by an edge reinforcement strip (9, 9', 9'') which is embedded in rubber,contains parallel load-bearing elements, characterized by that the strength carriers of the edge reinforcement strip (9, 9', 9'') are hybrid cords running at an acute angle of 15° to 30° to the circumferential direction, each consisting of at least one high-modulus yarn and one low-modulus yarn, where the force, normalized to the yarn fineness in tex, which must be applied to the high-modulus yarn, is > 300 mN / tex at 1% elongation and > 500 mN / tex at 2% elongation and where the force that must be applied to the low-modulus yarn, normalized to the yarn fineness in tex, is < 150 mN / tex at 1% elongation and < 200 mN / tex at 2% elongation. [2] Commercial vehicle tires according to claim 1, characterized by, that the edge reinforcement strip (9', 9'') covers the edge of the second, radially outer working layer (7) with an overlap width (b'') on this working layer (7) of at least 10 mm. [3] Commercial vehicle tires according to claim 1 or 2, characterized by , that the edge reinforcement strip (9'') only covers the edge of the second, radially outer working layer (7), whereby the edge reinforcement strip (9'') on the first, radially inner working layer (6) extends at most to the edge of this working layer (6). [4] Commercial vehicle tires according to claim 1 or 2, characterized by , that the edge reinforcement strip (9, 9') covers the edges of both working layers (6, 7). [5] Commercial vehicle tires with a four-ply belt (3) according to claim 1, characterized by, that the edge reinforcement strip (9) covers the edges of the two working layers (6, 7) and a fourth belt layer (8), wherein its overlap width (b) on the fourth belt layer (8) is at least 10 mm. [6] Commercial vehicle tires according to claim 5, characterized by , that the overlap width (b) on the fourth belt layer (8) is up to 15 mm. [7] Commercial vehicle tires according to any one of claims 4 to 6, characterized by , that the edge reinforcement strip (9, 9') extends beyond the edge of the first, radially inner working layer (6) by 5 mm to 15 mm. [8] Commercial vehicle tires according to any one of claims 1 to 7, characterized by that the high-modulus yarn in the hybrid cord consists of filaments made of aramid, glass or carbon. [9] Commercial vehicle tires according to any one of claims 1 to 8, characterized by , that the low-modulus yarn in the hybrid cord consists of filaments made of polyamide, in particular PA 6.6 or PA 6, or of PET. [10] Commercial vehicle tires according to any one of claims 1 to 9, characterized by , that the high-modulus yarn has a fineness of 1500 dtex to 1800 dtex, in particular of 1600 dtex to 1700 dtex. [11] Commercial vehicle tires according to any one of claims 1 to 10, characterized by , that the low-modulus yarn has a fineness of 1200 dtex to 1600 dtex, in particular of 1350 dtex to 1450 dtex. [12] Commercial vehicle tires according to any one of claims 1 to 11, characterized by , that the hybrid cord consists of two high-modulus yarns twisted together and one low-modulus yarn twisted together with the twisted high-modulus yarns. [13] Commercial vehicle tires according to any one of claims 1 to 12, characterized by , that the hybrid cords in the edge reinforcement strips (9, 9', 9'') run in the circumferential direction of the tire. [14] Commercial vehicle tires according to any one of claims 1 to 13, characterized by, that the inclination of the hybrid cords relative to the circumferential direction corresponds to the inclination of the reinforcing elements in the radially outer working position (7).

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