PNEUMATIC VEHICLE TIRE HAVING A BELT BANDAGE HAVING AT LEAST ONE BELT PLY

Abstract

A pneumatic vehicle tire with a belt assembly with at least one belt ply reinforced with steel cords embedded in rubber material. The steel cords each having the same number of steel filaments, are arranged parallel to one another and at at least substantially equal distances apart within each belt ply, have rubber coating layers on both sides, the layer thicknesses of which in total are 0.10 mm to 2.00 mm, when viewed in cross section are flattened open steel cords composed of four to six steel filaments periodically twisted together, at least two of which, when viewed in cross section, are flat-deformed, have a first larger diameter and a second smaller diameter perpendicular thereto, the ratio of which is between 1.10 and 3.00, and are embedded in the belt ply with their first, larger diameter lying largely flat and are at largely equal clear distances from one another, which are 0.10 mm to 1.00 mm.

Claims

1. A pneumatic vehicle tire comprising a belt assembly having at least one belt ply which is reinforced with steel cords embedded in rubber material, each of the steel cords having the same number of steel filaments, in which the steel cords: are arranged parallel to one another and at at least substantially equal distances apart within at least one belt ply, have rubber coating layers on both sides, the layer thicknesses of which in total are 0.10 mm to 2.00 mm, when viewed in cross section are flattened open steel cords composed of four to six steel filaments periodically twisted together, at least two of which, when viewed in cross section, are flat-deformed, have a first larger diameter and a second smaller diameter perpendicular thereto, the ratio of the first diameter to the second diameter is between 1.10 and 3.00, are at equal distances from one another, which the equal distances are from 0.10 mm to 1.00 mm.

2. The pneumatic vehicle tire as claimed in claim 1, wherein, when viewed in any cross section along the steel cords, in each case at least one steel filament is circular.

3. The pneumatic vehicle tire as claimed in claim 1, wherein, the steel cords are composed of five steel filaments and when viewed in any cross section along the steel cords, at least three of the steel filaments are flat-deformed, or the steel cords are composed of six steel filaments, d when viewed in any cross section along the steel cords, at least four steel filaments are flat-deformed.

4. The pneumatic vehicle tire as claimed in claim 1, wherein: the steel cords are composed of five steel filaments, and when viewed in any cross section along the steel cords, exactly one of the steel filaments is circular, or the steel cords are composed of four or six steel filaments, and when viewed in any cross section along the steel cords, exactly two steel filaments are circular.

5. The pneumatic vehicle tire as claimed in claim 1, wherein the following relationship applies to the steel cords in the belt ply: $D1=100/\mathrm{epdm}-\mathrm{Rg},$ where D1 is the first larger diameter of the steel cords and D1>0.20 mm, and where Rg is the clear distance between adjacent steel cords and epdm is the number of cords per 10 cm of belt ply width.

6. The pneumatic vehicle tire as claimed in claim 1, wherein the ratio (D1/D2) of the larger diameter (D1) to the smaller diameter (D2) of the steel cord is 1.20 to 1.90.

7. The pneumatic vehicle tire as claimed in claim 1, wherein the layer thicknesses of the rubber coating layers in total are 0.20 mm to ?1.00 mm.

8. The pneumatic vehicle tire as claimed in claim 1, wherein the layer thickness of the rubber coating layers are the same size or of different sizes, the layer thicknesses being at least 0.05 mm in each case.

9. The pneumatic vehicle tire as claimed in one of claim 1, wherein the belt ply contains flattened steel cords composed of five steel filaments.

10. The pneumatic vehicle tire as claimed in claim 1, wherein the belt ply contains flattened steel cords composed of five steel filaments and with a larger diameter of 0.50 mm to 0.70 mm, with the clear distance between the steel cords being 0.35 mm to 0.70 mm.

11. The pneumatic vehicle tire as claimed in claim 9, wherein the ratio of the larger diameter to the smaller diameter of the steel cords is 1.40 to 1.60.

12. The pneumatic vehicle tire as claimed in claim 1, wherein the belt ply contains flattened steel cords composed of five steel filaments and with a larger diameter>0.50 mm to 1.35 mm, with the clear distance between the steel cords being 0.50 mm to 0.90 mm.

13. The pneumatic vehicle tire as claimed in claim 9, wherein the ratio of the larger diameter to the smaller diameter of the steel cords is 1.70 to 1.80.

14. The pneumatic vehicle tire as claimed in claim 1, wherein the flattened steel cords are produced by deforming steel cords of cross-sectionally circular steel filaments with matching diameters of 0.18 mm to 0.45 mm.

15. The pneumatic vehicle tire as claimed in claim 1, wherein the flattened steel cords are produced by deforming steel cords of cross-sectionally circular steel filaments with diameters of 0.185 mm, 0.20 mm, 0.22 mm, 0.28 mm or 0.40 mm.

16. The pneumatic vehicle tire as claimed in claim 1, wherein the flattened steel cords are produced by deforming steel cords of cross-sectionally circular steel filaments with diameters of 0.18 mm to 0.45 mm, the relationship for the deformed, flattened steel cords being:
1.60d?D2?2.40d, where d is the diameter of the cross-sectionally circular steel filaments of the undeformed steel cords and D.sub.2 is the smaller diameter of the deformed, flattened steel cords.

17. The pneumatic vehicle tire of claim 1, in which the steel cords when viewed in cross-section are flat deformed in an irregular manner.

18. The pneumatic vehicle tire of claim 5, where D1>0.26 mm.

19. The pneumatic vehicle tire of claim 6, wherein the ratio (D1/D2) of the larger diameter (D1) to the smaller diameter (D2) of the steel cords is 1.40 to 1.80.

20. The pneumatic vehicle tire of claim 7, wherein the layer thicknesses of the rubber coating layers in total are 0.20 mm to 0.70 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Further features, advantages and details of the invention are now described in more detail on the basis of the drawing, which shows exemplary embodiments and in which:

[0028] FIG. 1 shows a schematic cross section of a variant of an embodiment of a flattened steel cord composed of five steel filaments,

[0029] FIG. 2 shows a schematic cross section of a non-flattened steel cord composed of five cross-sectionally circular steel filaments,

[0030] FIG. 3 shows a schematic cross section of a further variant of an embodiment of a flattened steel cord composed of six steel filaments,

[0031] FIG. 4 shows a schematic cross section of a non-flattened steel cord composed of six cross-sectionally circular steel filaments,

[0032] FIG. 5 shows a realistic cross section of a flattened steel cord composed of five steel filaments and

[0033] FIG. 6 shows a schematic cross section of a portion of a belt ply of a pneumatic vehicle tire with embedded, flattened and schematically shown steel cords composed of five steel filaments.

DETAILED DESCRIPTION

[0034] The present invention is concerned with the arrangement of flattened, cross-sectionally non-circular steel cords composed of four to six steel filaments in at least one of the belt plies of pneumatic vehicle tires of a radial design and of any type, preferably tires for passenger cars, light trucks or heavy-duty vehicles.

[0035] All dimensions specified in the description should be understood taking into account the usual production-related deviations.

[0036] The four to six steel filaments of the flattened steel cords are periodically twisted together or intertwined, so that an open steel cord is present in such a way that, when embedding the steel cords in a belt rubber coating compound, the material of the compound can penetrate into the gaps between the steel filaments, thereby filling them. Individual steel filaments may in this case also contact one another without affecting the penetrability. The steel filaments of the flattened steel cords have a common tensile strength of 2,500 N/mm.sup.2 to 4,500 N/mm.sup.2, the tensile strengths are therefore substantially in the range from NT (Normal Tensile) to UT (Ultra Tensile).

[0037] FIG. 1 shows a schematic cross section of a flattened steel cord 1 with five steel filaments 2, FIG. 3 shows a schematic cross section of a flattened steel cord 1 with six steel filaments 2. The production of the flattened steel cords 1 is performed in such a way that five or up to six steel filaments 2 of the same design and circular in cross section, with a diameter d of 0.10 mm to 0.60 mm, in particular of 0.18 mm to 0.45 mm, are twisted together so that the steel cords 1, that are round in cross section in FIG. 2 and FIG. 4 are formed as original cords. These original cords are deformed, for example by a rolling operation, so that in each case at least two steel filaments 2 are locally flattened or deformed, in particular in the region of their mutual contact points, and an irregularly flattened cross-sectional form is thereby at least partially obtained, with also the steel cord 1 being given overall a flattened cross-sectional shape. Due to the twisting of the steel filaments 2, when viewed in different cross sections over the length of the steel cord 1, steel filaments 2 are differently deformed; some may even not be deformed and then locally have their originally circular cross section. FIG. 5 shows this on the basis of a representation of a realistic cross section of a flattened steel cord 1 with five largely irregularly deformed steel filaments 2. The same applies to flattened steel cords composed of four steel filaments.

[0038] The flattened steel cords 1 have a larger diameter D.sub.1 and a diameter D.sub.2 at right angles to it, smaller compared to D.sub.1. The diameters D.sub.1 and D.sub.2 are the largest diameters in each case and are therefore determined at the locations with the largest widths of the steel cords 1. D.sub.1 is in this case>0.2 mm, in particular D.sub.1>0.26 mm, and the ratio of D.sub.1 to D.sub.2 is 1.10 to 3.00, preferably 1.20 to 1.90, particularly preferably 1.40 to 1.80. For the deformed, flattened steel cords 1, the relationship 1.60 d?D.sub.2?2.40 d applies with respect to the smaller diameter D.sub.2, where d is the diameter of the cross-sectionally circular steel filaments of the undeformed steel cords. The deformation or compression of the original cords is performed in particular in such a way that the deformed steel filaments 2 have their largest diameter d.sub.1 substantially parallel to the diameter D.sub.1 and a further smaller diameter d.sub.2 at right angles to it at its widest point, where the ratio of d.sub.2 to d.sub.1 is in the range of about 0.70 to about 0.98.

[0039] The flat-deformed steel filaments 2 each have a cross-sectional surface area which corresponds or largely corresponds to that of the originally circular steel filaments 2, because minor material shifts in the longitudinal direction of the steel filaments can take place locally in the deformation process.

[0040] FIG. 6 shows by way of example a cross section through a portion of a belt ply 3 of a pneumatic vehicle tire, the belt ply 3 being reinforced with schematically shown steel cords 1 with five steel filaments 2. Instead of the steel cords composed of five filaments shown, as described, steel cords of four or six filaments may also be contained in the belt ply 3. The clear distance R.sub.g between the steel cords 1 depends on the diameter D.sub.1 and the cord density (epdm, number of cords per decimeter belt ply) and ranges between 0.10 mm, in particular 0.30 mm, and 1.00 mm, where:

[00001]$D_1=100/\mathrm{epdm}-R_g,\mathrm{where}{D}_1>0,2\mathrm{mm},\mathrm{as}\mathrm{mentioned}\mathrm{above}.$

[0041] If, according to a preferred embodiment, the flattened steel cords have five steel filaments and a diameter D.sub.1 of 0.50 mm to 0.70 mm, the clear distance R.sub.g between the steel cords is 0.35 mm to 0.70 mm. If the diameter D.sub.1 of the flattened steel cords is >0.50 mm to 1.35 mm, the steel cords 1 are embedded in the belt ply 3 in such a way that their clear distance R.sub.g apart is 0.50 mm to 0.90 mm.

[0042] The overall thickness La of the belt ply 3 is the sum of the aforementioned smaller diameter D.sub.2 of the steel cords 1 contained in the belt ply 3 and the layer thicknesses R.sub.c and R.sub.b of the rubber coating layers present above and below the steel cords 1. The layer thicknesses R.sub.c and R.sub.b are in each case determined as the smallest clear distances between the steel cords 1 and the outer and inner outer surfaces of the belt ply 3. The sum of the two layer thicknesses R.sub.c and R.sub.b for flattened steel cords composed of four to six steel filaments is at least 0.10 mm and at most 2.00 mm, in particular up to 1.00 mm, preferably up to 0.70 mm, particularly preferably up to 0.60 mm. R.sub.c and R.sub.b may be the same size (on average) or of different sizes, so that there is an asymmetric rubber coating. A preferred range for the sum of R.sub.c and R.sub.b lies in the range from 0.20 mm to 0.60 mm.

[0043] Table 1, Table 2 and Table 3 contain data on preferred variants VAR1.1, VAR1.2, VAR2.1, VAR 2.2, VAR3 and VAR4 of an embodiment of belt plies with flattened steel cords 1 composed of five steel filaments 2 and comparative examples REF1.1, REF1.2, REF2 and REF3 of belt plies with steel cords that are known steel cords made according to the prior art. REF1.1 is the comparative example for the variants VAR1.1 and VAR2.1; REF1.2 is the comparative example for the variants VAR1.2 and VAR2.2. REF2 is the comparative example for the variant VAR3, and REF3 is the comparative example for the variant VAR4.

[0044] The comparative examples REF1.1, REF1.2, REF2 and REF3 contain steel cords of the constructions 2?0.30 mm HT, 2+2?0.32 mm HT and 3?0.2 mm+6?0.35 mm HT with cross-sectionally circular steel filaments.

[0045] The steel cords in the belt plies made according to the invention (VAR1.1 to VAR4) are flattened steel cords, for which, in the absence of better terminology, the originally circular diameter of the steel filaments is indicated in the steel cord construction; therefore 0.185 mm (construction referred to as 5?1.85 mm ST), also 0.20 mm (construction referred to as 5?0.20 mm ST), 0.28 mm (construction referred to as 5?0.28 mm ST) and 0.40 mm (construction referred to as 5?0.40 mm ST).

[0046] Other parameters in the tables are the cord diameter (REF1.1 to REF3), the diameter D.sub.1, the diameter D.sub.2, the ratio D.sub.1 to D.sub.2, the breaking force that can be withstood by the respective steel cord, determined according to ASTM D2969 and ASTM D4975, the tensile strength of the belt ply in kN/dm (calculated from the epdm and the breaking force that can be withstood by the respective cord), the belt thickness in mm, the clear distance between cords R.sub.g in mm and the number of cords per 10 cm of belt ply (epdm).

[0047] In the comparative examples REF1.1 to REF3, the belt ply weight is set to 100%, in the examples according to the invention VAR1.1 to VAR4 respectively in % and in relation to the respective comparative examples REF1.1 to REF3.

TABLE-US-00001 TABLE 1 REF1.1 REF1.2 VAR1.1 VAR1.2 VAR2.1 VAR2.2 Cord construction 2 ? 0.30 mm HT 5 ? 0.185 mm ST 5 ? 0.20 mm ST Cord diameter [mm] 0.60 0.60 Diameter D.sub.1 [mm] 0.60 0.60 0.66 0.66 Diameter D.sub.2 [mm] 0.40 0.40 0.44 0.44 Ratio of D.sub.1 to D.sub.2 1.5 1.5 1.5 1.5 Breaking force (N) 445 445 460 460 505 505 Tensile strength [kN/dm] 35.6 42.3 36.8 43.7 40.4 48.0 Clear distance between 0.65 0.45 0.65 0.45 0.59 0.39 cords R.sub.g [mm] Belt ply weight [%] 100.0% 100.0% 85.0% 85.7% 87.6% 88.1% Belt ply thickness [mm] 0.90 0.90 0.70 0.70 0.74 0.74 epdm 80 95 80 95 80 95

TABLE-US-00002 TABLE 2 REF2 VAR3 Cord construction 2 + 2 ? 0.32 5 ? 0.28 mm HT mm ST Cord diameter [mm] 0.83 Diameter D.sub.1 [mm] 0.94 Diameter D.sub.2 [mm] 0.53 Ratio of D.sub.1 to D.sub.2 1.77 Breaking force (N) 1010 980 Tensile strength [kN/dm] 65.7 63.7 Clear distance between cords R.sub.g [mm] 0.71 0.60 Belt ply weight [%] 100.0% 79.0% Belt ply thickness [mm] 1.30 0.83 epdm 65 65

TABLE-US-00003 TABLE 3 REF3 VAR4 Cord construction 3 ? 0.2 mm + 5 ? 0.40 6 ? 0.35 mm HT mm ST Cord diameter [mm] 1.13 Diameter D.sub.1 [mm] 1.30 Diameter D.sub.2 [mm] 0.75 Ratio of D.sub.1 to D.sub.2 1.74 Breaking force (N) 1980.0 1931.7 Tensile strength [kN/dm] 81.2 90.8 Clear distance between cords R.sub.g [mm] 1.31 0.83 Belt ply weight [%] 100.0% 86.1% Belt ply thickness [mm] 1.60 1.05 epdm 41 47

LIST OF REFERENCE SIGNS

[0048] 1, 1 . . . . . . . . . . . . . . . Steel cord [0049] 2, 2 . . . . . . . . . . . . . . . Steel filament [0050] 3. . . . . . . . . . . . . . . . . . . . Belt ply [0051] R.sub.g . . . . . . . . . . . . . . . . . . Distance [0052] R.sub.c, R.sub.b . . . . . . . . . . . . . Rubber coating layer thicknesses [0053] D.sub.1, D.sub.2 . . . . . . . . . . . . Diameter of steel cord [0054] d.sub.1, d.sub.2 . . . . . . . . . . . . . . Diameter of steel filament [0055] d. . . . . . . . . . . . . . . . . . . . Diameter of steel filament [0056] L.sub.d . . . . . . . . . . . . . . . . . . . Overall thickness of the belt ply