Profiled vehicle tire

Abstract

The present invention relates to a vehicle tire (1), preferably a pneumatic vehicle tire (1), with radially from the inside to the outside • a carcass (12), preferably with belt package and winding bandage, • a softer layer (13), • a stiffer layer (14) relative to the softer layer (13) and • a cap layer (15), wherein the cap layer (15) has a profiling (11) with grooves (11c) and blocks (11b), so that the cap layer (15) forms a profiled tread (10) towards the outside, wherein a transition region (18) is formed between each groove (11c) and block (11b), wherein the thickness of the softer layer (13) below the grooves (11c) and / or in the transition regions (18) is less than below the blocks (11b).

Description

[0001] The present invention relates to a profiled vehicle tire.

[0002] It is well known that various types of vehicles can be moved on wheels, or rather, rolled over a surface using wheels. Today, this is usually done with tires, which are located around the circumference of the wheel and transfer the forces between the wheel and the surface, such as a road. The part of the vehicle's tire, i.e., the tire itself, that is in contact with the ground, is commonly referred to as the tire contact patch, whose tread extends around the tire.

[0003] Tires are typically manufactured using vulcanizing molds. These molds consist of, among other things, molded parts that together form the tire's radially outer surface, such as the tread, as well as the remaining outer surfaces of the tire, such as the shoulder area, sidewalls, and bead area. The segments of the vulcanizing mold that form the tire's tread are called profile or mold segments.

[0004] The unvulcanized "green" tire is vulcanized in the vulcanizing mold and transformed into its final rubber-elastic state through rubber crosslinking reactions. The tire acquires its tread pattern through the corresponding negative shaping of the mold surfaces of the mold segments. Mold surfaces refer to those surfaces of the mold segments that give the tire its corresponding shape.

[0005] To define or improve the contact between the tire and the road surface, the tire's tread is typically profiled, meaning the tire has a profiled tread radially outward toward the road surface. The profiled tread typically consists of a specific arrangement of blocks separated by grooves.

[0006] The disadvantage here is that this leads to a different pressure distribution, similar to that of the underlying tire components, such as the carcass in the sense of a "classic" carcass plus belt package with a coiled bandage, depending on the radial position, either under a groove, under a block, or at a block edge. The inhomogeneous force exerted by the ground on the tire tread leads to a higher wear rate, higher rolling resistance, and higher noise levels.

[0007] Most premium Nordic winter tires do not have longitudinal grooves; instead, their main grooves form a V-shape. Two V-shaped grooves are typically connected by several lateral grooves that extend more or less perpendicular to the V-shaped grooves. This divides the tread into numerous blocks, which are typically further incised by a multitude of grooves. This results in different tire cross-sections around the tire's circumference in terms of the positions of blocks and grooves. This makes it difficult to harmonize the aforementioned uneven pressure distribution experienced by the tire around its circumference, as each circumferential position requires a different lateral balancing of the tire.

[0008] One object of the present invention is to provide a vehicle tire, in particular a Nordic winter tire, of the type described above with an improved or more harmonized pressure distribution than previously known. At the very least, an alternative to such known vehicle tires is to be created.

[0009] The object is achieved according to the invention by a vehicle tire according to independent claim 1. Advantageous further developments are described in the subclaims.

[0010] Thus, the present invention relates to a vehicle tire with radially from the inside to the outside • a carcass, preferably with belt package and spool bandage, • a softer layer, • a stiffer layer relative to the softer layer and • a cap layer, the cap layer having a profile with grooves and blocks, so that the cap layer forms a profiled tread on the outside, with a transition zone being formed between each groove and block, the thickness of the softer layer below the grooves and / or in the transition zones being less than below the blocks. The carcass can optionally also have a belt package including a wound bandage.

[0011] According to the invention, a layer with or consisting of a comparatively soft material is arranged between the carcass and the layer with or consisting of a comparatively stiff material, so that when the tread is formed, essentially or exclusively the material of the softer layer is displaced laterally and not the stiffer layer. The softness or stiffness of the material is determined as Shore A hardness at room temperature in accordance with DIN ISO 7697-1-2018-07. The comparatively stiff material below the tread or groove and in the transition area at the edges of the groove thus remains completely or essentially with its original thickness. Accordingly, the comparatively stiff material can absorb and distribute forces or pressures evenly across the entire tread when the vehicle tire is in use. This leads to a more harmonized pressure distribution than previously known.

[0012] In other words, according to the invention, the use of tread contouring over a horizontal multi-compound base represents a possibility for harmonizing the pressure distribution towards the carcass in a preferably V-shaped tread of a preferably Nordic vehicle tire. During tread formation, more material volume of the cap layer and the softer base compound of the relatively soft layer, preferably the relatively soft cap layer and the even softer base compound of the relatively soft layer, is pressed out from under the grooves or grooves compared to the relatively stiff base or stiffer layer. This results in softer base material under the blocks in the cured tire and consequently in a contoured transition line from bottom to top that adapts to the pattern at every position in the circumferential direction.

[0013] The comparatively high proportion of stiff substrate beneath the grooves or channels results in lower pressure, while the stiff-soft base combination in the blocks results in higher pressure exerted on the blocks by the groove edges, i.e., in the transition area. This allows for more homogeneous excitation of the blocks and thus improved wear, rolling resistance, and noise performance compared to a monobase variant, i.e., only the cap compound directly on the carcass, preferably with a belt package and wound bandage.

[0014] Further performance advantages in terms of wear, rolling resistance, and TSI (tire stiffness index) arise from the higher transition line between the stiff base and the cap compound, preferably Nordic, compared to a monobase, resulting in greater stiffness and thus less deformation under radial, circumferential, and lateral load application. Furthermore, in this configuration, a very low hysteresis compound could be used as the soft bottom base, further increasing rolling resistance. Typical of preferably Nordic tires is that the lower energy dissipation per unit deformation of a low hysteresis base is offset by its reduced stiffness, resulting in a higher degree of deformation.

[0015] According to one aspect of the invention, the thickness of the cap layer below the grooves and / or in the transition areas is less than below the blocks. This represents a specific result or feature of the tread pattern formation in the previously described finished vehicle tire, resulting from the previously described material properties of the layers with different stiffness and softness.

[0016] According to a further aspect of the invention, the thickness of the stiffer layer below the grooves and / or in the transition region corresponds to the thickness of the stiffer layer below the blocks. This represents a concrete result or feature of the tread pattern formation in the previously described finished vehicle tire, resulting from the previously described material properties of the layers with different stiffness or softness. This can promote the realization of a more harmonized pressure distribution.

[0017] According to a further aspect of the invention, the softer layer has the same softness as, or greater softness than, the cap mixture. These can represent concrete implementation possibilities for achieving the properties described above.

[0018] According to a further aspect of the invention, the cap layer has a greater softness than the stiffer layer. This can represent a concrete implementation option for achieving the properties described above.

[0019] According to a further aspect of the invention, the softer layer beneath the blocks has a thickness of 60% to 90% of the total thickness of the two layers, preferably 1.5 mm to 2.0 mm. The thickness or strength is to be understood in the radial direction. The total thickness of the two layers represents the sum of the thickness of the softer layer and the thickness of the stiffer layer. This can represent a concrete implementation possibility for achieving the properties described above.

[0020] According to a further aspect of the invention, the stiffer layer beneath the blocks has a thickness of 10% to 40% of the total thickness of the two layers, preferably 1.0 mm to 1.5 mm. This can represent a concrete implementation option for achieving the properties described above.

[0021] According to a further aspect of the invention, the vehicle tire consists, radially outward from the carcass, of the softer layer, the stiffer layer, and the cap layer. It should be understood that, apart from the three layers already described, no further layers or other elements are present radially outward from the carcass.

[0022] According to a further aspect of the invention, at least one groove, preferably all grooves, is V-shaped. This can represent a specific implementation option, which may be common or advantageous, particularly for winter tires.

[0023] According to a further aspect of the invention, the cap layer is a Nordic cap layer. This means that the cap layer comprises a material that is commonly used as a cap layer for winter tires. This can facilitate the implementation of the invention, particularly for winter tires.

[0024] An embodiment and further advantages of the invention are explained below in conjunction with the following figures. Therein: Fig. 1 shows a first cross section through a vehicle tire according to the invention; Fig. 2 shows a second cross-section, offset along the circumference, through the vehicle tire according to the invention; Fig. 3 a sectional plan view of the tread of the vehicle tire according to the invention; Fig. 4 a cross-section of an unvulcanized “green” tire blank of the vehicle tire according to the invention before forming the tread; Fig. 5 a cross-sectional view of a detailed view of the unvulcanized “green” tire blank of the vehicle tire according to the invention during the formation of the tread; and Fig. 6 the detailed view of the Fig. 5 in the molded and vulcanized state.

[0025] The description of the above figures is given in cylindrical coordinates with a longitudinal axis X, a radial direction R perpendicular to the longitudinal axis X and a circumferential direction U circulating around the longitudinal axis X. The longitudinal axis X, the radial direction R and the circumferential direction U can also be referred to together as spatial directions X, R, U or as cylindrical spatial directions X, R, U.

[0026] A vehicle tire 1 according to the invention in the form of a pneumatic vehicle tire 1 is considered, see for example Fig. 1, Fig. 2 and Fig. 5. From radially inside to outside, the pneumatic vehicle tire 1 has a carcass 12, preferably with a belt package and wound bandage, which forms a tire inner side 17 radially inward. Towards the radial outside, the carcass 12 is followed by a softer layer 13, which has a softer or relatively soft base compound 13, a stiffer layer 14, which has a stiffer or relatively stiff base compound 14, which has a Nordic cap layer 15, see for example Fig. 6. The radially outwardly directed surface or outer side of the Nordic cap layer 15 has a profiling 11 in the form of 11b, which is formed or spaced apart from each other or separated from each other by V-shaped grooves 11c arranged therebetween, which penetrate radially in a V-shape into the Nordic cap layer 15, see for example Fig. 1 to 3. The blocks 11b merge into the intermediate V-shaped groove 11c by means of a transition area 18, see for example Fig. 6. This forms a profiled tread 10, see for example Fig. 1 and Fig. 2. Tire sidewalls 16 are connected to the profiled tread 10 on both sides.

[0027] To form the profile 11, these three layers 13, 14, 15 are arranged one above the other in the unvulcanized “green” tire blank with a uniform thickness, see Fig. 4. Then, a vulcanization mold 2 with a molding surface 20, which has projections 21 and recesses 22, is pressed radially from the outside in the direction A of a closing movement into the unvulcanized “green” tire blank in order to form the grooves 11c and thus also the blocks 11b of the profile 11 of the profiled tread 10, see Fig. 5. Vulcanization then takes place in this state. The vulcanization mold 2 is then removed in direction B of an opening movement, see Fig. 4.

[0028] Due to the inventive structure of the three layers 13, 14, 15 on the carcass 12 and the different softnesses and stiffnesses—the softer layer 13 has the same softness or greater softness than the cap compound 15, and the cap layer 15 has greater softness than the stiffer layer 14—of the three layers 13, 14, 15, the formation of the tread pattern 11 of the profiled tread 10 results in the thickness of the softer layer 13 below the grooves 11c and in the transition regions 18 being less than below the blocks 11b. The thickness of the cap layer 15 below the grooves 11c and in the transition regions 18 is also less than below the blocks 11b. Furthermore, the thickness of the stiffer layer 14 below the grooves 11c and in the transition region 18 corresponds to the thickness of the stiffer layer 14 below the blocks 11b.

[0029] This results from the fact that, during the formation of the tread 11, the material of the softer layer 13 is displaced laterally in the direction of a material flow D. Likewise, the material of the cap layer 15 is displaced laterally in the direction of a material flow C. Thus, the comparatively stiff material of the stiffer layer 14 below the tread 11 or below the grooves 11c, as well as in the transition region 18 at the edges of the grooves 11c, remains completely or essentially unchanged at its original thickness. Accordingly, the comparatively stiff material of the stiffer layer 14 can evenly absorb and distribute forces or pressures across the entire tread when the pneumatic vehicle tire 1 is in use. This leads to a more harmonized pressure distribution than previously known. List of reference symbols (part of the description) A Direction of closing movement of the vulcanization mold 2 B Direction of the opening movement of the vulcanization mold 2 C Direction of material flow of the cap layer 15 D Direction of material flow of the softer layer 13 R radial direction U circumferential direction X Longitudinal axis 1 vehicle tires; pneumatic vehicle tires 10 profiled treads 11 Profiling 11b Blocks 11c (V-shaped) grooves 12 Carcass, preferably with belt package and spool bandage 13 softer layer; softer base mixture 14 stiffer layer; stiffer base mixture 15 (Nordic) cap layer 16 tire sidewalls 17 Tire inner side 18 Transition area between groove 11c and block 11b 2 Vulcanization mold 20 mold surface 21 projections 22 rebounds

Claims

[1] Vehicle tyres (1), preferably pneumatic vehicle tyres (1), with radially from the inside to the outside • a carcass (12), preferably with belt package and winding bandage, • a softer layer (13), • a stiffer layer (14) relative to the softer layer (13) and • a cap layer (15), wherein the cap layer (15) has a profiling (11) with grooves (11c) and blocks (11b), so that the cap layer (15) forms a profiled tread (10) towards the outside, wherein a transition region (18) is formed between the groove (11c) and the block (11b), wherein the thickness of the softer layer (13) below the grooves (11c) and / or in the transition regions (18) is less than below the blocks (11b). [2] Vehicle tire (1) according to claim 1, wherein the thickness of the cap layer (15) below the grooves (11c) and / or in the transition regions (18) is less than below the blocks (11b). [3] Vehicle tyre (1) according to claim 1 or 2, wherein the thickness of the stiffer layer (14) below the grooves (11c) and / or in the transition region (18) corresponds to the thickness of the stiffer layer (14) below the blocks (11b). [4] Vehicle tyre (1) according to one of the preceding claims, wherein the softer layer (13) has the same softness or a greater softness than the cap compound (15). [5] Vehicle tire (1) according to one of the preceding claims, wherein the cap layer (15) has a greater softness than the stiffer layer (14). [6] Vehicle tyre (1) according to one of the preceding claims, wherein the softer layer (13) below the blocks (11b) has a thickness of 60% to 90% of the total thickness of the two layers (13, 14), preferably of 1.5 mm to 2.0 mm. [7] Vehicle tyre (1) according to one of the preceding claims, wherein the stiffer layer (14) below the blocks (11b) has a thickness of 10% to 40% of the total thickness of the two layers (13, 14), preferably of 1.0 mm to 1.5 mm. [8] Vehicle tire (1) according to one of the preceding claims, wherein the vehicle tire (1) consists of the softer layer (13), the stiffer layer (14) and the cap layer (15) radially outwardly from the carcass (12). [9] Vehicle tire (1) according to one of the preceding claims, wherein at least one groove (11c), preferably all grooves (11c), are V-shaped. [10] Vehicle tire (1) according to one of the preceding claims, wherein the cap layer (15) is a Nordic cap layer (15).

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