Vehicle pneumatic tires

Abstract

Vehicle pneumatic tires with a tread having at least two circumferentially circumferential profile areas of certain widths, for example profile ribs (1, 2), each of which is composed of geometrically identical profile elements, so-called pitches (P1 to P5, P1' to P5'), arranged successively around the circumference, which are provided in at least three different circumferential lengths (L1 to L5, L1' to L5'), wherein the arrangement of the pitches (P1 to P5, P1' to P5') around the tire circumference in each profile area follows a separate noise-optimized pitch sequence, wherein the total number of pitches (P1 to P5, P1' to P5') in at least one circumferentially circumferential profile area differs from that in at least one further circumferentially circumferential profile area, characterized in thatthat the total number of pitches (P1 to P5) in the profile area with the highest total number is up to 3% greater than the total number of pitches (P1 to P5, P1' to P5') in the profile area with the lowest total number.

Description

[0001] The invention relates to a vehicle pneumatic tire with a tread having at least two circumferentially ring-shaped profile areas of certain widths, for example profile ribs, each of which is composed of geometrically identical profile elements, so-called pitches, arranged successively around the circumference, which are provided in at least three different circumferential lengths, wherein the arrangement of the pitches around the tire circumference in each profile area follows a separate noise-optimized pitch sequence, wherein the total number of pitches in at least one ring-shaped profile area differs from that in at least one further ring-shaped profile area.

[0002] When designing the tread pattern of pneumatic vehicle tires, it is common practice to assign different circumference lengths to the successive, identical tread sections, or pitches, around the tire's circumference in order to positively influence, reduce, and optimize tire / road noise. Typically, three to five different circumference lengths are incorporated into the tread, the ratios of which are predetermined, and the most noise-optimized sequence, the pitch sequence, is determined using suitable software.

[0003] Regarding the topic of pitches and pitch sequences of treads, numerous solutions can be found in patent literature. For example, a pneumatic tire of the type mentioned above is known from EP 0 114 594 B1. The tread of this pneumatic tire has two ring-shaped circumferential profile areas, each running in one half of the tread, whose identically designed pitches are arranged within pitch sequences whose total number differs from each other by 5% to 50%, and in particular by 10% to 30%. EP 0 412 952 B1 discloses a pneumatic tire with a profiled tread which, in the circumferential direction, is composed of identical pitches having at least two different circumferential lengths, the arrangement of which around the tire circumference follows a noise-optimized pitch sequence.Within the pitch sequence, there are at most two pitches whose length is either shorter than the second shortest pitch or longer than the second longest pitch. The known solutions primarily aim to achieve a distribution of the frequencies detected and occurring in tire / road noise over a wider frequency band.

[0004] US Patent 6,363,984 B1 discloses a vehicle tire with a tread having five circumferentially ring-shaped tread zones of specific widths, each tread zone being composed of pitches S, M, and L. The tread zones include a central tread zone that is free of any intersecting grooves. According to one embodiment, the tread zones located in one half of the tread are circumferentially offset from those located in the other half, such that the pitches S, M, and L are also offset from each other, which is intended to reduce tire / road noise. Similar results are said to be achievable by using different pitch sequences in the tread halves or different pitch sequences in the tread zones.

[0005] From DE 696 12 102 T2, a vehicle tire is known with a tread having a total of 67 to 103 pitches with four or five different pitch lengths, wherein the ratio of the length of the longest pitch to the length of the shortest pitch is a maximum of 1.58, the ratio of the lengths of two pitches immediately following each other in the circumferential direction is a maximum of 1.43, and the longest pitch does not immediately follow the shortest pitch. The pitch lengths differ such that the differences to the next larger and next smaller pitch lengths are equal. This pitch length variation is intended to ensure low tire / road noise.

[0006] Certain pitch sequences, pitch length ratios and / or the use of two or more pitch sequences in different tread areas can theoretically result in quiet or low tire / road noise; however, in practice, pitch sequences and pitch lengths cannot be arbitrarily combined in a tread, as this would lead to uneven wear or poor aquaplaning properties, for example.

[0007] The invention is based on the objective of designing a vehicle pneumatic tire with a tread of the type mentioned above in such a way that the subjective perception of the tire / road noise is significantly improved, while ensuring other desirable tread properties, in particular uniform wear of the tread.

[0008] The problem is solved according to the invention by ensuring that the total number of pitches in the profile area with the largest total number is up to 3% greater than the total number of pitches in the profile area with the smallest total number.

[0009] By designing the tread with ring-shaped, circumferential profile zones containing varying total numbers of pitches that differ only slightly from one another, particularly smooth excitation spectra can be generated. This measure also allows the pitch sequences to be designed to be relatively similar to each other and to be well coordinated. The small difference in the total number of pitches allows the identical profile elements within the profile zones to be arranged in such a way that a stiffness distribution is present across the entire tread, ensuring uniform wear.

[0010] In a preferred embodiment of the invention, the different total numbers of pitches in the profile regions share several of the numbers 1 to 5 as a common divisor. This measure particularly effectively prevents the subharmonics of the different pitch sequences from "coinciding." Especially through small common divisors, such as the numbers 1 to 5, it can be avoided that spectral regions with increased excitation coincide in the excitation spectra of the intended different pitch sequences.

[0011] In this context, an embodiment of the invention is particularly advantageous in which the different total numbers of pitches in the profile areas have only the number 1 as a common divisor.

[0012] Furthermore, a particularly quiet tire / road noise can be achieved by having the tread pattern have two tread areas with different pitch sequences, whereby the total number of pitches in the tread areas differs from each other by a maximum of two pitches.

[0013] In a tread design according to the invention, it is further advantageous if the number of different pitch lengths in the tread areas is up to seven, particularly if this number is at most five. With more than seven different pitch lengths, the geometric design and the arrangement of the different pitch lengths around the tire circumference become relatively complex; designs with up to five different pitch lengths are optimal.

[0014] Further optimization of tire / road noise can be achieved through specific additional measures and designs. These include, for example, selecting the number of different pitch lengths in one tread area in such a way that it differs from the number of different pitch lengths in another tread area.

[0015] Within the scope of the invention, the tread can be designed with geometrically variable features; circumferential grooves, transverse grooves, cuts, and the like can be implemented in the individual profile areas according to the specified requirements. In particular, it is possible for the tread to have at least two profile areas designed according to the invention, wherein the pitches in the profile areas are geometrically identical. In another embodiment, the tread can have at least two profile areas designed according to the invention, wherein the pitches in the profile areas are geometrically different.

[0016] Further advantageous measures can help to optimize the stiffness distribution in the tread and, in particular, to ensure uniform wear. These measures include, for example, ensuring that the ratio of the length of the longest pitch to the length of the shortest pitch is 1:1.4. Another advantageous measure in this context is that the total number of pitches in the tread area with the fewest pitches is at least 90, and in particular at least 120. Further features, advantages, and details of the invention will now be described in more detail with reference to the drawing, which schematically depicts an exemplary embodiment. The single figure shows, Fig. 1, a section of the circumference of a tread of a vehicle tire.

[0017] In Fig. Figure 1 shows a shoulder-side profile rib 1 and another profile rib 2, separated from profile rib 1 by a wide circumferential groove 3, of a radial vehicle tire for passenger cars, vans, and the like. Instead of profile ribs, circumferential profile block rows can also be provided. In the illustrated embodiment, another circumferential groove 3' runs along the inside of the tread of profile rib 2, to which profile positives (not shown) connect. Both profile rib 1 and profile rib 2 are structured in a block-like manner; profile rib 1 by transverse grooves 4, and profile rib 2 by transverse grooves 5. In the embodiment shown Fig. In the schematically shown embodiment, the transverse grooves 4 are arranged such that they terminate on the inside of the tread within the profile rib 1 and thus at a distance in front of the circumferential groove 3. On the outside of the tread, they extend beyond the lateral edge of the tread's ground contact area width B, which is symbolized by a dashed line, and terminate in this area, i.e., on the outside of the tread. The ground-contacting portion of the tread corresponds to the statically determined footprint according to ETRTO standards (load at 70% of the bearing capacity at an internal pressure of 2.5 bar, internal pressure 85% of 2.5 bar). The transverse grooves 5 in the profile rib 2 are, by way of example, transverse grooves that terminate in a sac-like manner within the profile rib 2 and open into the circumferential groove 3'. The design and course of the transverse grooves 4 and 5 are not part of the invention and will therefore not be discussed in detail.

[0018] Profile rib 1 forms a first, ring-shaped profile section that extends circumferentially, occupying a portion of the width B of the tread. Profile rib 2 forms a second, ring-shaped profile section that also extends circumferentially over a portion of the tread's contact area width B. Both profile rib 1 and profile rib 2 are each composed of identical profile elements arranged in a circumferential sequence, also called profile pitches. In the illustrated embodiment, the pitch boundaries between the pitches are located approximately midway between successive transverse grooves 4 and 5 and follow the course of these grooves. However, the pitch boundaries can also be positioned elsewhere, for example, at the edge of transverse grooves 4 and 5 that are positioned in the same direction circumferentially.The pitches in each depicted profile area have their own geometric design, but it is also possible that the geometric designs of the pitches in the profile areas are the same.

[0019] The division of the profile elements into pitches of different circumference lengths, which are arranged around the circumference within a so-called pitch sequence that is calculated, is common and serves the purpose of minimizing or optimizing tire / road noise and distributing or generating the audible frequencies that arise when the tire rolls in such a way that they are as little disturbing as possible to the human ear.

[0020] In the illustrated embodiment, the pitch sequences in profile rib 1 and in profile rib 2 each consist of the same number of pitches of different lengths, according to Fig. 1. An example consisting of pitches P1 to P5 and P1' to P5' with circumferential lengths L1 to L5 and L1' to L5', wherein the pitch sequence and the total number of pitches P1 to P5 in profile rib 1 differ from the pitch sequence and the total number of pitches P1' to P5' in profile rib 2. In the Fig.In the embodiment shown in Figure 1, with five different circumferential lengths L1 to L5 and L1' to L5', their length ratios are such that the ratio of the length L1 or L1' of the shortest pitch P1 or P1' to the length L5 or L5' of the longest pitch P5 or P5' is 1:1.4. The lengths L1, L2, L3, L4, and L5, as well as the lengths L1', L2', L3', L4', and L5', are preferably in the ratio 1:1, 1:1, 2:1, 3:1.4 to each other. In contrast to the embodiment shown, three to seven pitches with different circumferential lengths can be provided, preferably with a length ratio of 1:1.4 between the shortest and the longest pitch. If a profile area contains a certain number of pitches of different lengths with defined circumferences, for example five, then the same number of pitches of different lengths can be used in the other profile area(s).However, different numbers of pitches of varying lengths may be provided in the individual profile areas.

[0021] The total number of pitches in one profile rib 1 differs from the total number of pitches in the second profile rib 2 by a maximum of 3%. This means that the profile area with the greater total number of pitches has up to 3% more pitches than the other profile area. Any rounding to whole pitches is carried out according to DIN 1333. With three or more profile areas with different pitch sequences in the tread, the one with the greatest total number of pitches has up to 3% more pitches than the profile area with the smallest total number of pitches. A particularly advantageous design is a tread with two profile areas with different pitch sequences, in which the profile area with the greater total number of pitches has at most two pitches, in particular one pitch, more than the other profile area.

[0022] Regarding the total number of pitches in the intended ring-like circumferential profile areas of certain widths—in the illustrated embodiment, these are exemplified by the two profile ribs 1 and 2—the design is preferably such that the different total numbers have several of the numbers 1 to 5 as common divisors. In a preferred embodiment, which is particularly advantageous, the total numbers have only 1 as a common divisor. These measures prevent the subharmonics of the two pitch sequences from "coinciding." Thus, by using small common divisors, as mentioned, or by using a design with only 1 as a common divisor, it is avoided that areas of increased excitation in the excitation spectra of the two pitch sequences meet.This measure is particularly advantageous in profile areas with a relatively high total number of pitches, especially a total number > 90, and most preferably a total number > 120, since the number of common divisors usually increases with the total number of pitches in a profile area. For example, the total number of pitches in one profile area implemented in the tread pattern can be 144 and in a second implemented profile area 145.

[0023] The concept according to the invention can thus be applied to treads that have two ring-shaped circumferential profile areas or consist of two ring-shaped circumferential profile areas, wherein a profile area can also include two or more profile ribs, profile block rows, and the like. The concept according to the invention is, of course, also applicable to treads that have more than two ring-shaped circumferential profile areas with different pitch sequences. Reference number list 1, 2 profile rib 3, 3 circumferential groove 4, 5 transverse groove B Ground contact area width L1 to L5 circumference length L1' to L5' Circumference length P1 to P5 Pitch P1' to P5' Pitch

Claims

[1] Vehicle pneumatic tires with a tread having at least two circumferentially circumferential profile areas of certain widths, for example profile ribs (1, 2), each of which is composed of geometrically identical profile elements, so-called pitches (P1 to P5, P1' to P5'), arranged successively around the circumference, which are provided in at least three different circumferential lengths (L1 to L5, L1' to L5'), wherein the arrangement of the pitches (P1 to P5, P1' to P5') around the tire circumference in each profile area follows a separate noise-optimized pitch sequence, wherein the total number of pitches (P1 to P5, P1' to P5') in at least one circumferentially circumferential profile area differs from that in at least one other circumferentially circumferential profile area, characterized by, that the total number of pitches (P1 to P5) in the profile area with the largest total number is up to 3% greater than the total number of pitches (P1 to P5, P1' to P5') in the profile area with the smallest total number. [2] Vehicle pneumatic tires according to claim 1, characterized by , that the different total numbers of pitches (P1 to P5, P1' to P5') in the profile areas have several of the numbers 1 to 5 as a common divisor. [3] Vehicle pneumatic tires according to claim 1, characterized by , that the different total numbers of pitches (P1 to P5, P1' to P5') in the profile areas have only the number 1 as a common divisor. [4] Vehicle pneumatic tires according to any one of claims 1 to 3, characterized by , that the tread has two profile areas (1, 2) with different pitch sequences, wherein the total number of pitches in the profile areas (1, 2) differs from each other by at most two pitches. [5] Vehicle pneumatic tires according to any one of claims 1 to 4, characterized by , that the number of different pitch lengths (P1 to P5, P1' to P5') in the profile areas is up to seven. [6] Vehicle pneumatic tires according to any one of claims 1 to 5, characterized by , that the number of different pitch lengths (P1 to P5, P1' to P5') in the profile areas is up to five. [7] Vehicle pneumatic tires according to any one of claims 1 to 6, characterized by , that the number of pitches of different lengths in one profile area differs from the number of pitches of different lengths in another profile area. [8] Vehicle pneumatic tires according to any one of claims 1 to 7, characterized by that the tread has at least two profile areas in which the pitches are geometrically identical. [9] Vehicle pneumatic tires according to any one of claims 1 to 7, characterized bythat the tread pattern has at least two profile areas in which the pitches are geometrically different from each other. [10] Vehicle pneumatic tires according to any one of claims 1 to 9, characterized by , that the ratio of the length (L5, L5') of the longest pitch (P5, P5') to the length (L1, L1') of the shortest pitch (P1, P1') is 1 : 1.

4. [11] Vehicle pneumatic tires according to any one of claims 1 to 10, characterized by that the total number of pitches (P1 to P5, P1' to P5') in the profile area which has the lowest total number is at least 90, in particular at least 120.

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