Reinforcement layer of a vehicle tire and vehicle tire with such a reinforcement layer

Description

[0001] The invention relates to a reinforcement layer of a vehicle pneumatic tire, comprising a strip-shaped section made of a plurality of reinforcing elements arranged parallel to one another and embedded in rubber material, wherein the strip-shaped section has a longitudinal axis and two edge edges extending parallel to the longitudinal axis, and the reinforcing elements extend at an angle to the longitudinal axis between the edge edges of the section, wherein adjacent reinforcing elements each have different lengths and are arranged such that their ends, viewed in the direction of the longitudinal axis, are offset from one another in a step-like manner with respect to the edge edges. The invention further relates to a corresponding vehicle pneumatic tire.

[0002] Conventional pneumatic tires for passenger cars and light commercial vehicles have a structure in which at least one reinforcement layer consisting of reinforcing elements embedded in rubber material is provided beneath the radially outer tread, which also carries the tire profile. In their uninstalled, raw state, these reinforcement layers are formed as strip-shaped sections. The reinforcing elements, usually steel or plastic wires, are cut using a guillotine shear or similar tool so that a straight edge is created in the area of ​​the outer edges; that is, a connecting line through all the ends of the reinforcing elements running in the direction of the longitudinal axis runs parallel to the longitudinal axis and the outer edges of the reinforcement layer.

[0003] Typically, several of these reinforcing layers are arranged on top of each other in such pneumatic tires as a belt pack, with the reinforcing elements providing high stiffness to the individual reinforcing layers and the entire belt pack. However, stiffness decreases significantly in the area of ​​the edge edges where the reinforcing elements terminate. To prevent the decrease in stiffness towards the edge edges of a belt pack from being too abrupt, the individual reinforcing layers are cut to different widths and stacked on top of each other. Nevertheless, due to the straight cut, there is still a significant change in stiffness for each individual reinforcing layer. Therefore, the individual edge edges are often covered by a rubber insert or a ply wrap to improve the tire's durability.

[0004] Furthermore, US 3 719 218 A and US 3 841 376 A disclose the ability to trim the edge edges of the reinforcement layer in a zigzag or wavy pattern, which, however, results in individual reinforcing elements being cut multiple times and creating edge peaks in which only very short length sections of individual reinforcing elements are embedded, leading to durability problems.

[0005] WO 03 / 045714 A1 discloses reinforcement layers in which the individual reinforcing bars are cut to the same length and several adjacent reinforcing bars are grouped into packages. Successive packages are arranged with an axial offset from one another. However, due to the grouping of several adjacent reinforcing bars into packages, this design also exhibits a significant change in stiffness, which appears to be in need of improvement.

[0006] JP S61 37501 A discloses the design of a reinforcement layer with alternating longer and shorter reinforcing elements, wherein the longer reinforcing elements are cut together with the embedding rubber layers along straight edge edges and thus have a slanted cut edge, which further leads to undesirably high stress peaks in the edge areas.

[0007] From JP H09 2016 A, it is known to lay two layers of identical but differently lengthened reinforcing elements on top of each other and embed them in rubber compound to form a reinforcement layer. All reinforcing elements are cut along straight edges, which also lead to stress concentrations in the edge regions that could be improved.

[0008] From JP 2005 041455 A, a generic design of a reinforcement layer is known in which shorter and longer reinforcing elements alternate. The reinforcing elements are embedded in rubber material, and the entire reinforcement layer exhibits zigzag-shaped edge profiles. The resulting stiffness modulation and durability remain unsatisfactory.

[0009] The object of the invention is to propose a reinforcement layer for a vehicle pneumatic tire that overcomes the disadvantages of the prior art.

[0010] To solve the stated problem, the invention proposes a reinforcement layer in accordance with the features of claim 1. Advantageous embodiments and further developments of the reinforcement layer according to the invention are the subject of the dependent claims.

[0011] Furthermore, the invention also proposes a vehicle pneumatic tire equipped with at least one such reinforcement layer according to the invention.

[0012] The inventive proposal is based on the fact that adjacent reinforcing beams in the direction of the longitudinal axis each have different lengths and are arranged such that their ends are offset from each other in a step-like manner in the direction of the longitudinal axis with respect to the edge edges.

[0013] Within the scope of the invention, an arrangement of three successive reinforcing beams of different lengths is proposed, wherein either a) a first load-bearing element of the arrangement is designed with a greater length than the next adjacent load-bearing element, followed by an adjacent third load-bearing element which has a length between the lengths of the first and second load-bearing elements, or b) the first load-bearing element of the arrangement has a medium length, the subsequent second load-bearing element has the greatest length and the adjacent third load-bearing element has the shortest length in comparison to the arrangement, and this arrangement is then repeated several times in the direction of the longitudinal axis.

[0014] According to the invention, it is possible to assemble the reinforcing elements into a reinforcement layer such that an imaginary connecting line of the ends facing the edge edges has an irregular profile with a multitude of different slopes, undercuts, overlaps, and the like. It has been shown within the scope of the invention that, with this design, the bending stiffness of the reinforcement layer decreases over a greater area towards the edge edges when viewed across its width. This ensures that the overall stiffness of a tire belt assembly formed from several such reinforcement layers gradually decreases towards the edge edges. This makes it possible to dispense with previously required rubber inserts or layer folds, which not only offers cost advantages but also reduces the rolling resistance of a tire designed in this way.

[0015] The invention defines a stepped arrangement as an arrangement in which the imaginary connection of the ends of more than two adjacent load-bearing elements is not a straight line, but is subject to abrupt changes in direction.

[0016] According to one proposal of the invention, the reinforcing elements are each formed from steel wires, with each reinforcing element comprising only one or more such steel wires.

[0017] To further increase the gradual stiffness reduction of the reinforcement layer according to the invention, it is proposed that the reinforcing elements be cut at right angles to their ends with respect to their longitudinal axis. In this way, stress peaks at the respective ends of the individual reinforcing elements are minimized.

[0018] The reinforcement layer described above enables the construction of belt packages of a vehicle pneumatic tire in which the changes in bending stiffness are distributed over a larger area, resulting in a significantly improved belt durability overall.

[0019] A vehicle pneumatic tire according to the invention is characterized in that it has at least one reinforcement layer of the type described above, preferably several such reinforcement layers combined into a belt package.

[0020] Further embodiments and details of the invention are explained below with reference to the drawings illustrating exemplary embodiments. These show: Figure 1 is a schematic top view of an embodiment of the invention; Figure 2 is a schematic top view of a further embodiment of the invention; Figure 3 is a schematic top view of an embodiment according to the prior art; Figure 4 is a schematic top view of a further embodiment according to the prior art; Figure 5 is an enlarged view of the end of a single reinforcing element according to the invention; Figure 6 is a top view of a reinforcement layer of a vehicle pneumatic tire.

[0021] From the Figure 6 A schematic top view shows a reinforcement layer of a vehicle pneumatic tire, such as is used below the tread to form a belt package.

[0022] The reinforcement layer is formed as a strip-shaped section 1 consisting of a multitude of parallel reinforcing elements 10, which are formed from one or more bundled steel wires and are arranged at an angle of, for example, 45° to the longitudinal axis L of section 1. The individual reinforcing elements 10 are embedded in a rubber material (not shown) and extend from the left edge R1 to the right edge R2, with both edges R1 and R2 running parallel to the longitudinal axis L.

[0023] In a typical embodiment known from the prior art, which is described in the Figure 4As shown, the individual reinforcement carriers 10 are cut to a common, identical length during the production of the reinforcement layer, for example by means of a guillotine shear, i.e. the ends 100 of the individual reinforcement carriers 10 run along a straight connecting line parallel to the longitudinal axis L with respect to the edge edges R1 (not shown) and R2.

[0024] If one considers the stiffness of this reinforcement layer according to the state of the art across the width from the central longitudinal axis L to the edge, represented here by R2, the following arises in the Figure 4 The characteristic shown as curve K4 exhibits a step-like decrease in bending stiffness at the ends 100 of the individual reinforcing members 10. This is problematic for durability.

[0025] In the embodiment not belonging to the invention according to Figure 3A strength beam 10 of greater length is followed by a strength beam 10 of a correspondingly shorter length. This arrangement is then repeated several times in the direction of the longitudinal axis L.

[0026] In the embodiments according to the invention Figures 1 and 2 The adjacent reinforcement members 10 are each formed in different lengths and arranged such that their ends 100 are offset from each other in a step-like manner in the direction of the longitudinal axis L with respect to the edge edges, here represented by R2.

[0027] Thus, in the exemplary embodiment according to Figure 1The lowest, first reinforcement beam 10 is designed with a greater length than the adjacent next reinforcement beam 10, followed by an adjacent third reinforcement beam 10, which has a length between the lengths of the first and second reinforcement beams 10. This arrangement is then repeated several times in the direction of the longitudinal axis L.

[0028] In the exemplary embodiment according to Figure 2 The first, lowest reinforcing beam 10 has a medium length, the subsequent second reinforcing beam 10 has the greatest length, and the adjacent third reinforcing beam 10 has the shortest length in comparison. This arrangement is then repeated several times in the direction of the longitudinal axis L.

[0029] As a result, the embodiments according to the invention yield the following: Figures 1-2An imaginary connecting line between the ends 100 of adjacent reinforcement beams 10 does not have a straight course, as the ends 100 of adjacent reinforcement beams are arranged in a stepped offset from each other due to their different length dimensions. This results in a frayed-looking arrangement of the ends 100 of the reinforcement beams in the area of ​​the edge edges R1, R2. Considering again the stiffness of this reinforcement layer from the central longitudinal axis L to the edge edges, represented here by R2, the following results for the configurations according to Figures 1-2 The curves K1 and K2 shown in each case, in which, compared to curve K4, there is no step-like decrease in stiffness in the area of ​​the edge edges 2, but rather a gradual decrease, which is reflected in a significantly improved durability of a vehicle pneumatic tire equipped in this way.

[0030] To further reduce stress peaks in the area of ​​the edge edges R1, R2, the individual ends 100 of the reinforcing beams 10 can be shaped according to the illustration in Figure 5 be cut perpendicular to the longitudinal axis LA of the individual reinforcing beam 10.

[0031] It is understood that several such reinforcement layers can be placed on top of each other, preferably with the reinforcing elements 10 intersecting, and combined to form a belt package. It is also possible to arrange individual reinforcement layers designed according to the invention as described above. Figures 1-2 with a uniform design as in Figure 4 to combine as shown. Reference symbol list:

[0032] 1: Section 10: Reinforcing beam 100: End L: Longitudinal axis of the section LA: Longitudinal axis of the reinforcing beam R1: Edge R2: Edge K1: Stiffness curve in Figure 1 K2: Stiffness curve in Figure 2 K3: Stiffness curve in Figure 3 K4: Stiffness curve in Figure 4

Claims

1. Reinforcing ply of a vehicle pneumatic tyre comprising a strip-shaped portion (1) consisting of a multiplicity of reinforcing materials (10) arranged in parallel and embedded in rubber material, wherein the strip-shaped portion (1) has a longitudinal axis (L) and two outer edges (R1, R2) running parallel to the longitudinal axis (L), and the reinforcing materials (10) extend at an angle with respect to the longitudinal axis (L) between the outer edges (R1, R2) of the portion (1), -wherein adjacent reinforcing materials (10) each have different lengths and are arranged in such a way that, as viewed in the direction of the longitudinal axis (L), their ends (100) are arranged offset in a step-wise manner with respect to each other in relation to the outer edges (R1, R2), characterized in that an arrangement of three successive reinforcing materials (10) of different lengths is provided, wherein either a) a first reinforcing material (10) of the arrangement is formed with a longer length than the adjacent next reinforcing material (10), followed by an adjacent third reinforcing material (10) which has a length between the length of the first and second reinforcing material (10), or b) the first reinforcing material (10) of the arrangement has a middle length, the subsequent second reinforcing material (10) has the greatest length, and the adjacent third reinforcing material (10) has the comparatively smallest length of the arrangement, and this arrangement is then repeated multiple times in the direction of the longitudinal axis (L).

2. Reinforcing ply according to Claim 1, characterized in that the reinforcing materials (10) are each formed from steel wires.

3. Reinforcing ply according to either of Claims 1 or 2, characterized in that the reinforcing materials (10) each comprise one or more steel wires.

4. Reinforcing ply according to one of Claims 1 to 3, characterized in that the reinforcing materials (10) are cut to size at the end at right angles in relation to their longitudinal axis (LA).

5. Pneumatic vehicle tyre, comprising at least one reinforcing ply according to one of the preceding claims.