Vehicle pneumatic tires

Abstract

Vehicle tires with two bead areas (1) with bead cores (2), wherein each bead core (2) is wound spirally from a linear reinforcement carrier (8) to form an annular bead core (2), characterized in that the linear reinforcement carrier (8) is a cord made of non-metallic materials and has at least two intertwined linear elements, preferably yarns, and that the cord - either a cord (8) made of non-metallic high-modulus material, preferably PBO is - or a hybrid cord (8) wherein one linear element is made of a non-metallic, high-modulus material and wherein another linear element is made of a non-metallic, low-modulus material.

Description

[0001] The invention relates to a vehicle tire with two bead areas with bead cores, wherein each bead core is wound spirally from a linear reinforcement carrier to an annular bead core.

[0002] Tires with bead cores are well known. Bead cores ensure a secure and stable fit of the tire on the rim and therefore require sufficiently high tensile strength. On the other hand, the tire must be able to be mounted onto the rim over the rim flange, for which the bead core must also possess a certain degree of elasticity.

[0003] A bead core is typically manufactured by wrapping a suitable bronze-plated steel wire with a rubber compound specifically formulated for the core wire in a core winding machine and spirally winding it into a ring-shaped bead core. Steel offers sufficient tensile strength and the necessary elongation. However, steel's high specific gravity is a disadvantage, resulting in a heavy tire with this steel wire bead core, which negatively impacts the tire's rolling resistance.

[0004] To positively influence the weight and thus the rolling resistance of a vehicle tire, various linear reinforcement elements for ring-wound bead cores have already been proposed. These elements, in addition to a non-metallic material, always incorporate steel wires or filaments. For example, DE 41 37 726 A1 discloses the production of a wound bead core from both steel cords and cords made of aromatic polyamide wires. The steel wire cords are located in the interior of the bead core's cross-section, while the aromatic polyamide wire cords are arranged in the exterior of the cross-section. Furthermore, JP 2010-173437 A discloses the use of steel wires as reinforcement elements, which are coaxially encased by a woven layer of aramid.

[0005] The invention is based on the objective of providing a vehicle tire with bead cores that allow the tire to be easily mounted on the rim, ensure a secure fit on the rim, and exhibit improved rolling resistance. Furthermore, the vehicle tire should be more durable.

[0006] The problem is solved by the linear strength carrier being a cord made of non-metallic materials and having at least two intertwined linear elements, preferably yarns, and by the cord - either a cord (8) made of non-metallic high-modulus material, preferably PBO is - or is a hybrid cord in which one linear element is made of a non-metallic, high-modulus material and another linear element is made of a non-metallic, low-modulus material.

[0007] A pneumatic tire with bead cores made exclusively of non-metallic materials has been created, resulting in a lower specific gravity than previously used steel wires / filaments or combinations of non-metallic and metallic bead cores. This positively influences the tire's rolling resistance. Furthermore, corrosion-prone materials are omitted, and the non-metallic reinforcing elements used do not corrode, thus improving the tire's durability.

[0008] The reinforcing material is either a PBO cord with sufficient elasticity to allow a tire with a bead core made of PBO cord to be mounted on the rim.

[0009] Alternatively, the cord is a hybrid reinforcement element, which is made of at least one high-modulus, high-strength material, preferably yarn, and one low-modulus material, preferably yarn, twisted together. This hybrid cord allows the vehicle tire to be easily mounted on the rim because the low-modulus material, serving as a filler element, deflects the high-modulus material element into a geometrically helical shape, thus making it structurally elastic.

[0010] The high-strength, high-modulus material ensures a secure fit of the vehicle tire on the rim.

[0011] The non-metallic material for the bead core has a specific gravity of less than 3 g / cm³. 3 , preferably less than 1.7 g / cm³ 3 on.

[0012] Such a bead core is produced by a core winding machine analogous to a core made of standard core wire, whereby the hybrid cord is sheathed with a core wire mixture and wound ring-shaped to form a bead core.

[0013] The term "element" refers to yarn or filament.

[0014] The terms "high-modulus material, preferably yarn" and "low-modulus material, preferably yarn" are defined based on the yarn values ​​in (mN / tex) described in Table 1 below. This determines the force that must be applied to a yarn at 1% elongation and at 2% elongation, normalized to the yarn count in tex. The determination is performed according to ASTM D885. Table 1 Yarn / Stretch 1% 2% Low modulus < 150 mN / tex < 200 mN / tex High modulus > 300 mN / tex > 500 mN / tex

[0015] Preferably, the non-metallic high-modulus material is a yarn made of aramid or PBO with the trade name ZYLON®.

[0016] Preferably, the non-metallic, low-modulus material is a yarn made of PES or polyamide. Suitable materials include those that meet the parameters listed in Table 1, such as PA66, PA6, PET, staple fiber aramid, etc.

[0017] The preferred material combinations for hybrid cord made from high-modulus and low-modulus yarns are: - Aramid + PES or - PBO + PES.

[0018] It is advantageous if the diameter of the cord or hybrid cord is between 0.5 mm and 3.0 mm, preferably between 0.7 mm and 0.9 mm. A diameter of the (hybrid) cord between 0.5 mm and 3.0 mm corresponds to the diameter of a steel wire proven effective as a bead core wire. Hybrid cords with a diameter of 0.8 to 1.6 mm are readily available on the market. The advantage of a hybrid cord with a diameter of 0.7 mm and 0.9 mm is that existing equipment for manufacturing the bead core, tire building machines, and existing tire constructions can be used.

[0019] It is advantageous if the hybrid cord consists of two or three twisted yarns that are end-twisted together. This creates the helical component necessary for generating the geometric elongation of the high-modulus material.

[0020] In a hybrid cord made of three yarns, it is advantageous to twist two high-modulus yarns together, which are then end-twisted with a low-modulus yarn. Such a construction is described as high-modulus material x2 + low-modulus material x1.

[0021] The hybrid cord is symmetrical or asymmetrical with regard to yarn fineness and its twisting.

[0022] If the hybrid cord has a high-modulus x2 + low-modulus x1 construction, the yarn count is highly asymmetrical, while the twist is preferably symmetrical. "x2" means 2 yarns, "x1" means 1 yarn.

[0023] Table 2 below lists two preferred embodiments of reinforcing elements which can be used as bead cores in vehicle tires according to the invention, along with their essential properties. Table 2 PBO 1640x2 + 470x1 PBO 1640x2 BF [N] 660 1030 Elong. At Break [%] 4,0 3,3 Twist [t / m] 200 210 Tenacity [mN / dtex] 176 314

[0024] It is advantageous if the bead core is a rectangular core, a vertical core, or a hexagonal core.

[0025] The weight advantage achieved by a vehicle tire according to the invention is described with reference to the examples shown in Table 3. A steel wire used for a prior art bead core is compared with two cords (see Table 2) used for bead cores of vehicle tires according to the invention.

[0026] In a passenger car tire with dimensions 205 / 55R16, the bead core typically consists of a linear reinforcement made of steel wire, with the bead core having a 4x5 construction. This means that, viewed in cross-section, the core is a rectangular core with four wires arranged side by side in five rows each. The steel wire has a diameter of 0.89 mm and a length of 25 m. The steel bead core thus weighs approximately 122 g. In contrast, the vehicle tire according to the invention, with a bead core made of a non-metallic textile hybrid cord or cord of the construction specified in Tables 2 and 3, weighs only approximately 8–9 g per bead core, thus achieving a weight saving of 113–114 g per bead core and therefore a weight saving of 225–228 g per tire. Table 3 steel wire 0.89 mm Hybrid cord PBO 1640x2 + PA6.6 470x1 KordPBO 1640x2 Weight [g / 100 m] 488 37,5 32,8 Weight [%] 100 7,7 6,7 Twist [t / m] 140 200 210 Tenacity [mN / dtex] 103 176 314 Tires 205 / 55 R16 Length of reinforcing bar per bead core [m] 25 25 25 Weight per bead core [g] 122 9 8 Weight advantage [g] per reinforcement element per bead core 113 114 Weight advantage [g] per vehicle tire 226 228

[0027] Preferably, the vehicle tire is a pneumatic tire for passenger cars, vans or light commercial vehicles (LT).

[0028] Further features, advantages and details of the invention will now be explained in more detail with reference to a single drawing which represents a schematic embodiment.

[0029] This shows Fig. 1 a cross-section through the bead area of ​​a vehicle tire according to the invention.

[0030] In Fig.Figure 1 shows a cross-section through the bead area 1 of a vehicle pneumatic tire according to the invention, which is mounted on a rim. Only the rim seat 6 including the rim flange 7 is shown. The vehicle pneumatic tire is a 205 / 55 R16 tire for passenger cars. In the bead area 1, a bead core 2 of the 4x5 construction is arranged, which is enclosed by a carcass layer 3 from axially inside to axially outside and terminates as a carcass riser 3a. A bead rib 4 is arranged on the bead core 2. The largely airtight inner layer 5 is arranged axially inside.

[0031] The bead core 2 consists of a rubberized linear reinforcement element 8, which is wound spirally around the ring-shaped bead core 2. The linear reinforcement element 8 is a hybrid cord made of three twisted linear yarns of non-metallic materials with the construction PBO 1640x2 + PA6.6 470x1. Each hybrid cord is shown schematically in cross-section as a circle; the three yarns of each hybrid cord are not shown. Two yarns with a fineness of 1640 dtex are made of PBO, a non-metallic, high-modulus material. The third yarn has a fineness of 470 dtex and is made of PA6.6, a non-metallic, low-modulus material. The yarns are twisted together to form a hybrid cord. The weight advantage compared to a conventional steel wire bead core is described in Table 3. Reference symbol list 1 bead area 2 bead core 3 carcass layers 3a Carcass high impact 4 core riders 5 inner layer 6 rim seat 7 rim flange 8 Strength components aR axial direction rR radial direction QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 41 37 726 A1

[0004] JP 2010-173437 A

[0004]

Claims

[1] Vehicle tire with two bead areas (1) with bead cores (2), wherein each bead core (2) is wound spirally from a linear strengthening element (8) to form an annular bead core (2), characterized by , that the linear reinforcement element (8) is a cord made of non-metallic materials and has at least two intertwined linear elements, preferably yarns, and that the cord - either a cord (8) made of non-metallic high-modulus material, preferably PBO is - or a hybrid cord (8) wherein one linear element is made of a non-metallic, high-modulus material and wherein another linear element is made of a non-metallic, low-modulus material. [2] Vehicle tires according to claim 1, characterized by that the non-metallic high-modulus material is a yarn made of aramid or PBO. [3] Vehicle tires according to any one of the preceding claims, characterized bythat the non-metallic, low-modulus material is a yarn made of PES or polyamide. [4] Vehicle tires according to any one of the preceding claims, characterized by , that the diameter of the cord or hybrid cord (8) is between 0.5 mm and 3.0 mm, preferably in a range of 0.7 mm and 0.9 mm. [5] Vehicle tires according to any one of the preceding claims, characterized by , that the cord (8) or the hybrid cord (8) consists of at least two twisted yarns which are twisted together at the ends. [6] Vehicle tires according to any one of the preceding claims, characterized by , that the hybrid cord (8) has the construction PBO 1640dtex x 2 + PA6.6 470dtex x 1 or PBO 1640dtex x 2. [7] Vehicle tires according to any one of the preceding claims, characterized by , that the bead core (2) is a rectangular core, a vertical core, a hexagonal core. [8] Vehicle tires according to any one of the preceding claims, characterized bythat this is a pneumatic tire for cars, vans or LTs.

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