PNEUMATIC TIRE FOR A VEHICLE

Abstract

The invention relates to a pneumatic tire for a vehicle, having at least one surface element (2) that is formed on the outer surface of the tire and has a structure (6) which contrasts with a base level (N.sub.B) and gives the surface element (2) a roughness.

The contrast structure (6) is formed by a multiplicity of contrast structure cells (6a), which coincide in shape in plan view and are joined together in the form of a grid, wherein the contrast structure cells (6a) have irregular peak and trough structures (6b) of a surface-covering configuration, wherein the arrangement of the contrast structure cells (6a) and the configuration of the irregular peak and trough structures (6b) are such that, when considered in plan view, the irregular peak and trough structures (6b) can be transferred one into the other by congruence mapping.

Claims

1.-15. (canceled)

16. A pneumatic tire for a vehicle, the tire comprising: at least one surface element formed on an outer face of the tire and has a structure that contrasts with a base level (N.sub.B) and gives the surface element (2) a roughness, wherein the contrast structure is formed by a plurality of contrast structure cells that coincide in shape in a plan view and are joined together in the form of a grid, wherein the contrast structure cells have irregular peak and trough structures of a surface-covering configuration, wherein the arrangement of the contrast structure cells and the configuration of the irregular peak and trough structures are such that, when considered in plan view, the irregular peak and trough structures can be transferred one into the other by congruence mapping.

17. The tire of claim 16, wherein the peak and trough structures (6b), considered in plan view, can be transferred one into the other by parallel displacement of the contrast structure cells (6a).

18. The tire of claim 16, wherein the contrast structure cells (6a) in plan view have the shape of rectangles, in particular squares, or hexagons, in particular regular hexagons.

19. The tire of claim 16, wherein the contrast structure cells (6a) have an edge length (l) of 0.8 mm to 1.5 mm, in particular of up to 1.2 mm, preferably of 1.0 mm.

20. The tire of claim 16, wherein the peak and trough structure (6b) of each contrast structure cell (6a) with a height surface region (f.sub.1), extending over the region of the contrast structure cell (6a), of a first height surface (F.sub.1), which extends parallel to the base level (N.sub.B) of the contrast structure (6) and, with respect thereto, lies at a height (h.sub.1) of 80 m, has a single- or multi-part sectional surface (s.sub.1), which occupies 80% to 90% of the height surface region (f.sub.1).

21. The tire of claim 16, wherein the peak and trough structure (6b) of each contrast structure cell (6a) with a height surface region (f.sub.2), extending over the region of the contrast structure cell (6a), of a second height surface (F.sub.2), which extends parallel to the base level (N.sub.B) of the contrast structure (6) and, with respect thereto, lies at a height (h.sub.2) of 150 m, has a single- or multi-part sectional surface (s.sub.2), which occupies 40% to 60% of the height surface region (f.sub.2).

22. The tire of claim 16, wherein the peak and trough structure (6b) of each contrast structure cell (6a) with a height surface region (f.sub.3), extending over the region of the contrast structure cell (6a), of a third height surface (F.sub.3), which extends parallel to the base level (N.sub.B) of the contrast structure (6) and, with respect thereto, lies at a height (h.sub.3) of 200 m, has a single- or multi-part sectional surface (s.sub.3), which occupies 20% to 40% of the height surface region (f.sub.3).

23. The tire of claim 16, wherein the peak and trough structure (6b) of each contrast structure cell (6a) with a height surface region (f.sub.4), extending over the region of the contrast structure cell (6a), of a fourth height surface (F.sub.4), which extends parallel to the base level (N.sub.B) of the contrast structure (6) and, with respect thereto, lies at a height (h.sub.4) of 280 m, has a single- or multi-part sectional surface (s.sub.4), which occupies 10% to 20% of the height surface region (f.sub.4).

24. The tire of claim 16, wherein the height surface regions (f.sub.4) of the fourth height surface (F.sub.4) separate peak regions (6c) from the other peak and trough structure (6), wherein up to five, in particular up to three, peak regions (6c) sit on each height surface region (f.sub.4) and preferably have, at their highest points, a height (h.sub.max), determined with respect to and perpendicular to the base level (N.sub.B), of 300 m to 350 m.

25. The tire of claim 16, wherein the peak and trough structure (6b) of each contrast structure cell (6a) with height surface regions (f.sub.1, f.sub.2, f.sub.3, f.sub.4) which extend over the region of the contrast structure cell (6a) and which belong to height surfaces (F.sub.1, F.sub.2, F.sub.3, F.sub.4) extending parallel to the base level (N.sub.B) of the contrast structure (6) has, in each case, a single- or multi part sectional surface (s.sub.1, s.sub.2, s.sub.3, s.sub.4), wherein a first height surface (F.sub.1) with respect to the base level (N.sub.B) lies at a height (h.sub.1) of 80 m, a second height surface (F.sub.2) with respect to the base level (N.sub.B) lies at a height (h.sub.2) of 150 m, a third height surface (F.sub.3) with respect to the base level (N.sub.B) lies at a height (h.sub.3) of 200 m, and a fourth height surface (F.sub.4) with respect to the base level (N.sub.B) lies at a height (h.sub.4) of 280 m, wherein the following relationships apply: a) size of the sectional surface (s.sub.4) with the height surface region (f.sub.4) of the fourth height surface (F.sub.4)0.7 the size of the sectional surface (s.sub.3) with the height surface region (f.sub.3) of the third height surface (F.sub.3), b) size of the sectional surface (s.sub.3) with the height surface region (f.sub.3) of the third height surface (F.sub.3)0.7 the size of the sectional surface (s.sub.2) with the height surface region (f.sub.2) of the second height surface (F.sub.2), and c) size of the sectional surface (s.sub.2) with the height surface region (f.sub.2) of the second height surface (F.sub.2)0.7 the size of the sectional surface (s.sub.1) with the height surface region (f.sub.1) of the first height surface (F.sub.1).

26. The tire of claim 16, wherein the contrast structure (6), along the mutual connection points of the contrast structure cells (6a), has trough structures (6d) so that the grid pattern of the contrast structure (6) is visible to the naked eye.

27. The tire of claim 16, wherein the trough structures (6d), starting from a side, facing away from the base level (N.sub.B), of a height surface (F.sub.2) which, with respect to the base level (N.sub.B), lies at a height (h.sub.2) of 150 m, have a width of at least 0.1 mm.

28. The tire of claim 16, wherein the contrast structure (6) has smooth transitions of peak and trough structures between the contrast structure cells (6a), so that the grid pattern of the contrast structure (6) is not visible to the naked eye.

29. The tire of claim 16, wherein the contrast structure (6), in each plane (E.sub.1) arranged perpendicular to the base level (N.sub.B), has a height profile with multiple local maxima (P.sub.max) and local minima (P.sub.min) arranged successively in alternation, wherein a height difference (h) of 80 m to 300 m, measured perpendicular to the base level (N.sub.B), exists between each local minimum (P.sub.min) and each of the two directly adjacent local maxima (P.sub.max).

30. The tire of claim 16, wherein local minima (P.sub.min) and adjacent local maxima (P.sub.max) are provided, between which the height difference (h) is at least 100 m, preferably at least 150 m.

Description

[0036] Further features, advantages and details of the invention will now be described in more detail with reference to the drawing, which schematically shows an exemplary embodiment of the invention. In the drawing:

[0037] FIG. 1 shows a schematic plan view of a circumferential portion of a sidewall of a pneumatic tire for a vehicle with a design variant of the invention,

[0038] FIG. 2 shows a plan view of a micrograph in the region of a surface element situated on the sidewall,

[0039] FIG. 3a and FIG. 3b show views of the micrograph from FIG. 2, wherein a first height surface is drawn in each case,

[0040] FIG. 4a and FIG. 4b show views analogous to FIG. 3a and FIG. 3b, wherein a second height surface is drawn in each case,

[0041] FIG. 5a and FIG. 5b show further views analogous to FIG. 3a and FIG. 3b, wherein a third height surface is drawn in each case,

[0042] FIG. 6a and FIG. 6b show further views analogous to FIG. 3a and FIG. 3b, wherein a fourth height surface is drawn,

[0043] FIG. 7a shows an oblique view of a portion of the micrograph from FIG. 2, wherein the micrograph is sliced along a plane E1, and

[0044] FIG. 7b shows a height profile of the micrograph in the plane E1 from FIG. 7a.

[0045] The invention is concerned with surface elements which are formed on the outer surface of pneumatic tires for vehicles and have a special contrast structure.

[0046] The surface elements are formed on the outer surface in a region which does not come into contact with the ground or does not come into surface contact with the ground when the pneumatic tire for a vehicle is in use, in particular on sidewalls, on the tread edge, i.e. on the shoulder flanks running outside the ground contact area to the sidewalls, or on groove flanks and/or groove bottoms of grooves running in the tread. As a particular preference, the surface elements are formed on a sidewall. Sidewalls of pneumatic tires for vehicles generally include symbols which represent the prescribed information, such as dimensional information, the speed index, the manufacturer or the purpose (summer/winter tires), or other symbols, such as logos or design elements. The surface elements having a special contrast structure can surround the symbols mentioned on the sidewall and/or can themselves form the symbols.

[0047] The surface elements can also be formed on the tread, i.e. on that region of the outer surface of the tread which comes into contact with the ground when the pneumatic tire for a vehicle is in use.

[0048] The level with respect to which the contrast structure of the surface elements is formed on the tire is referred to below as the base level N.sub.B. The base level N.sub.B is the level from which the positives of the contrast structure are raised, as explained below.

[0049] The contrast structure is preferably formed in the course of vulcanization of the pneumatic tire for a vehicle. The mold segment(s) of the vulcanization mold, for example the side shells, is/are provided with a laser engraving corresponding to the contrast structure. The contrast structure is therefore a positive of the laser engraving and thus a positive with respect to the base level N.sub.B. For example, if a side shell is directly provided with a laser engraving, the level of the sidewall is the base level N.sub.B. For example, if an elevation formed on the side shell is provided with a laser engraving, the base level N.sub.B is the level of the bottom of a shallow depression formed on the sidewall.

[0050] Alternatively, the contrast structure can be laser engraved on the finished vulcanized tire. The resulting base level N.sub.B is thus offset towards the inside of the tire with respect to the non-engraved level surrounding the base level.

[0051] FIG. 1 shows a schematic illustration, projected into the plane, of a circumferential portion of a sidewall 1 with a surface element 2 which has substantially the form of a portion of a circular ring. A tread edge 3 and an outer bead region 4, which is at least partially covered by a rim when the tire is mounted on the rim, are additionally indicated in FIG. 1. The surface element 2 surrounds lettering 5, the letters A B C of which have a smooth surface. The lettering 5 is thus not part of the surface element 2.

[0052] FIG. 2 shows a plan view of a micrograph of a partial region of the surface element 2, wherein a square grid (square lattice) with grid lines r is drawn in. In FIG. 3a to FIG. 6a, the base level N.sub.B is indicated in each case by grid lines.

[0053] The surface element 2 is provided over the full area, i.e. over its entire extent, with a three-dimensional contrast structure 6 (FIG. 1), which imparts roughness, i.e. unevenness, to the surface element 2 (FIG. 3a to FIG. 6a). As indicated in FIG. 2 by the aforementioned square grid, the contrast structure 6 in the exemplary embodiment is composed of a plurality of contrast structure cells 6a which adjoin one another in a checkerboard fashion, are square in plan view with respect to their outer circumference, and are designed to be substantially coincident. The contrast structure cells 6a have an edge length l of 0.8 mm to 1.5 mm, in the exemplary embodiment of 1.0 mm, wherein in FIG. 2 only a single contrast structure cell 6a can be seen completely and partial regions of eight contrast structure cells 6a adjacent thereto.

[0054] The term contrast structure cells 6a designed to be substantially coincident means, on the one hand, those which have been generated (engraved) in a coincident manner directly on the outer surface of the tire (in the exemplary embodiment, on the sidewall) by means of a software-controlled laser. On the other hand, contrast structure cells 6a designed to be substantially coincident are understood to be those which were generated in the course of vulcanization by a corresponding laser engraving located on the inside of the mold segment (in the exemplary embodiment, the side shell), wherein the laser engraving comprises a plurality of engraving regions which adjoin one another and which were each generated in a coincident manner by means of a software-controlled laser. Due to the melting and evaporation processes occurring during laser engraving, it is not possible to produce identical (100% coincident) contrast structure cells 6a on the outer surface of pneumatic tires for vehicles using the methods currently available. This applies both to contrast structure cells 6a produced indirectly by laser engraving of the molded parts and to contrast structure cells 6a produced directly by laser engraving of the vulcanized rubber material. The term substantially coincident therefore refers to deviations occurring within the technical tolerance limits of the production process (software-controlled laser engraving).

[0055] As shown in particular in FIG. 2 in combination with FIG. 3a, each contrast structure cell 6a has an irregular peak and trough structure 6b, which is formed in an area-covering manner, and therefore over the entire contrast structure cell 6a, and has irregular peak structures with peak ridges and peak saddles as well as irregular trough structures, wherein both the peak structures and the trough structures run over different levels relative to the base level N.sub.B or are located at different levels. As has already been mentioned, the contrast structure cells 6a are substantially coincident, such that they have substantially coincident irregular peak and trough structures 6b. The irregular peak and trough structures 6b, as seen in plan view, are transferable into each other by (twist-free) parallel displacement of the contrast structure cells 6a. To illustrate this fact, in FIG. 2 in each contrast structure cell 6a the same partial region of a peak structure or the part of this partial region to be seen is provided with a hatching.

[0056] The further shape of the contrast structure cells 6a is explained below with the aid of height surfaces F.sub.1, F.sub.2, F.sub.3 and F.sub.4 (FIG. 3a to FIG. 6a, FIG. 3b to FIG. 6b). The height surfaces F.sub.1, F.sub.2, F.sub.3 and F.sub.4 extend parallel to the base level N.sub.B, and intersect the irregular peak and trough structure 6b at various heights h.sub.1 (height surface F.sub.1, FIG. 3a), h.sub.2 (height surface F.sub.2, FIG. 4a), h.sub.3 (height surface F.sub.3, FIG. 5a) and h.sub.4 (height surface F.sub.4, FIG. 6a) determined perpendicular with respect to the base level N.sub.B. Height h.sub.1 is 80 m, height h.sub.2 is 150 m, height h.sub.3 is 200 m, and height h.sub.4 is 280 m. In each contrast structure cell 6a, the height surfaces F.sub.1, F.sub.2, F.sub.3 and F.sub.4corresponding to the size of a contrast structure cell 6ahave a 1 cm1 cm height surface region f.sub.1, f.sub.2, f.sub.3, f.sub.4 (FIG. 3b to FIG. 6b). In each contrast structure cell 6a, the irregular peak and trough structure 6b with the associated height surface region f.sub.1, f.sub.2, f.sub.3, f.sub.4 has, in each case, a single-part or multi-part sectional surface s.sub.1, s.sub.2, s.sub.3, s.sub.4 (FIG. 3b to FIG. 6b), which is part of the height surface region f.sub.1, f.sub.2, f.sub.3, f.sub.4 and which is provided with a hatching in FIG. 3b to FIG. 6b. In the region of each sectional surface s.sub.1, s.sub.2, s.sub.3, s.sub.4, the height surface region f.sub.1, f.sub.2, f.sub.3, f.sub.4 is penetrated by the irregular peak and trough structure 6b (compare FIG. 3a to FIG. 6a). The sectional surface s.sub.1 occupies 80% to 90% of the height surface region f.sub.1 (FIG. 3b), the sectional surface s.sub.2 occupies 40% to 60% of the height surface region f.sub.2 (FIG. 4b), the sectional surface s.sub.3 occupies 20% to 40% of the height surface region f.sub.3 (FIG. 5b), and the sectional surface s.sub.4 occupies 10% to 20% of the height surface region f.sub.4 (FIG. 6b). Here, the relationship s.sub.4<s.sub.3<s.sub.2<s.sub.1 applies. More preferably, the relationships s.sub.40.7 s.sub.3, s.sub.30.7 s.sub.2 and s.sub.20.7 s.sub.1 also apply.

[0057] As FIG. 6a and FIG. 6b show, each height surface region f.sub.4 separates peak regions 6c from the rest of the peak and trough structure 6b, i.e. from the region of the peak and trough structure 6b below the respective height surface region f.sub.4. In this context, a peak region 6c is a contiguous peak region of the peak and trough structure 6b which sits on, i.e. is adjacent to, the height surface region f.sub.4 or the height surface F.sub.4. Within the contrast structure cell 6a, there are preferably three to twenty, in particular five to fifteen, peak regions 6c sitting on the height surface region f.sub.4. At their highest points, the peak regions 6c each have a height h.sub.max (FIG. 6a), determined with respect to and perpendicular to the base level N.sub.B, of 300 m to 350 m.

[0058] According to FIG. 2, the contrast structure 6 in the shown exemplary embodiment has trough structures 6d along the grid lines r free of positives, which make the grid pattern of the contrast structure 6, i.e. the mutual connection points of the contrast structure cells 6a, visible to the naked eye. Beginning at the latest from the height surface F.sub.2 (compare FIG. 4a) on the side, facing away from the base level N.sub.B, of the height surface F.sub.2, the trough structures 6d have a width of at least 0.1 mm-0.05 mm on each side of the grid line rdetermined perpendicular to the grid lines. The trough structures 6d can also have the aforementioned width below the height surface F.sub.2, i.e. in the region between the height surface F.sub.2 and the base level N.sub.B, and can also run or be formed at the base level N.sub.B, i.e. have the aforementioned width at the base level N.sub.B.

[0059] FIG. 7a shows the micrograph from FIG. 2 in an oblique view, wherein the contrast structure 6 is cut open along a plane E1 running parallel to the grid lines r (compare FIG. 2) and perpendicular to the base level N.sub.B, wherein the plane E1 does not run within one of the trough structures 6d, butcorresponding to the detail shownintersects two of the trough structures 6d (compare FIG. 2). FIG. 7b showsin enlarged form compared to FIG. 7athe height profile of the contrast structure 6 in the plane E1, wherein the base level N.sub.B is drawn. In the plane E1, the height profile of the contrast structure 6 has a large number of successive local maxima P.sub.max and local minima P.sub.min. At each local maximum P.sub.max, the height of the contrast structure 6 determined with respect to and perpendicular to the base level N.sub.B decreases on both sides. At each local minimum P.sub.min, the height of the contrast structure 6 increases on both sides. In the plane E.sub.1, a local minimum P.sub.min alternately follows a local maximum P.sub.max several times. Between each local minimum P.sub.min and the two immediately adjacent local maxima P.sub.max, there is a height difference h of 80 m to 300 m. Particularly preferred are local minima P.sub.min and adjacent local maxima P.sub.max between which the height difference h is at least 100 m, preferably at least 150 m. The contrast structure 6 preferably has a height profile with such local minima P.sub.min and adjacent local maxima P.sub.max in each plane perpendicular to the base level N.sub.B, which does not run exclusively through a trough structure 6d.

[0060] According to an alternative embodiment, the grid pattern of the contrast structure 6 is not visible to the naked eye. This is achieved by omitting trough structures 6d and smooth transitions of peak and trough structures between the contrast structure cells 6a.

[0061] The invention is not limited to the exemplary embodiment described.

[0062] The contrast structure cells in plan view may have a shape that deviates from the square shape described. Preferably, the contrast structure cells are each bounded by a number of straight edges in plan view. Particularly preferably, the contrast structure cells have the shape of rectangles, in particular squares, or hexagons, in particular regular hexagons. Considered in plan view, the contrast structure cells of the contrast structure are transferable into one another by at least one congruence mapping. The congruence mappings include, in a known manner, reflections (more precisely point reflections and perpendicular axis reflections, but not circle reflections and oblique reflections), rotations, parallel displacements (translations) and sliding reflections (thrust reflections). Therefore, contrast structure cells can also be provided, which can be transferred into each other by executing a plurality of different congruence mappings.

LIST OF REFERENCE SIGNS

[0063] 1 . . . Sidewall [0064] 2 . . . Surface element [0065] 3 . . . Edge of the tread [0066] 4 . . . Outer bead region [0067] 5 . . . Lettering [0068] 6 . . . Contrast structure [0069] 6a . . . Contrast structure cell [0070] 6b . . . Peak and trough structure [0071] 6c . . . Peak region [0072] 6d Trough structure [0073] E.sub.1 . . . Plane [0074] F.sub.1, F.sub.2, F.sub.3, F.sub.4 . . . Height surface [0075] f.sub.1 f.sub.2, f.sub.3, f.sub.4 . . . Height surface region [0076] h.sub.1, h.sub.2, h.sub.3, h.sub.4, h.sub.max . . . Height [0077] h . . . Height difference [0078] l . . . Edge length [0079] N.sub.B . . . Base level [0080] P.sub.min . . . Local minimum [0081] P.sub.max . . . Local maximum [0082] r . . . Grid line [0083] s.sub.1, s.sub.2, s.sub.3, s.sub.4 . . . Sectional surface