EP4341105A1

EP4341105A1 - Pneumatic vehicle tire having a belt bandage having at least one belt ply

Info

Publication number: EP4341105A1
Application number: EP22716331.8A
Authority: EP
Inventors: Mihail Catana; Daniel De Castro Pinho; Thomas Kramer; Michael Schunack
Original assignee: Continental Reifen Deutschland GmbH
Current assignee: Continental Reifen Deutschland GmbH
Priority date: 2021-05-20
Filing date: 2022-03-24
Publication date: 2024-03-27
Also published as: WO2022242810A1; DE102021205127A1; CN117320892A

Abstract

A pneumatic vehicle tyre having a belt bandage having at least one belt ply (3) which is reinforced with steel cords (1) which each have the same number of steel filaments (2) and are embedded in rubber and, within each belt ply, are arranged parallel to one another and with at least substantially equal distances to one another (Rg), have rubberization layers on both sides, the layer thicknesses (Rc, Rb) of which add up to 0.10 mm to 2.00 mm, when viewed in cross section are flattened, open steel cords (1) composed of four to six steel filaments (2) periodically twisted together, at least two of which viewed in cross section are flattened, especially in an irregular manner, have a first, relatively large diameter and, perpendicular thereto, a second, relatively small diameter (D1, D2), the ratio of which to one another is 1.10 to 3.00, and are embedded in the belt ply (3) with their first, relatively large diameter (D1) lying substantially flat and have substantially equal clearances (Rg) to one another of 0.10 mm to 1.00 mm.

Description

description

Pneumatic vehicle tire with a belt structure with at least one belt layer

The invention relates to a pneumatic vehicle tire with a belt assembly with at least one belt layer which is reinforced with steel cords embedded in rubber material and each having the same number of steel filaments.

Belt layers in pneumatic vehicle tires are essential components for the durability of the pneumatic vehicle tires, they ensure in particular the stability of the tires when driving straight ahead and cornering, even at high speeds. Due to the steel cords, belt plies contribute significantly to the overall weight of the tires, with the lowest possible tire weight being desirable in view of the rolling resistance of the tires. A number of requirements are also placed on the steel cords in the belt layers of pneumatic vehicle tires, for example, and depending on the type of tire, high tensile strength and flexural rigidity, high fatigue resistance and corrosion resistance. It is now already known, for example from KR 101019719 B1, to reinforce belt plies with flat steel cords made from three to nine steel filaments and with an open structure in order to reduce the thickness of the belt plies and thus reduce the tire weight by reducing the rubber material achieve. It was also recognized that belt plies with flat steel cords have a higher flexural rigidity in the lateral direction, while the flexural rigidity in the radial direction of the tire is comparatively lower. Tires with belt layers of this type therefore have improved driving comfort and high stability, the latter being advantageous when cornering, for example. The open structure of the steel cords ensures good penetration of the rubber compound between the individual filaments, which reduces fatigue and the so-called fretting phenomenon. The object of the invention is to optimize the balance between the stability of the belt assembly and a low weight in a pneumatic vehicle tire in order to reduce the rolling resistance and at the same time to ensure a high durability of the tire.

The stated object is achieved with a pneumatic vehicle tire with at least one belt ply, which is reinforced with steel cords which are arranged parallel to one another within each belt ply and at least essentially the same distance from one another,

- have rubber coating layers on both sides, the layer thicknesses of which total 0.10 mm to 2.00 mm, - viewed in cross section, are flattened open steel cords made of four to six steel filaments that are periodically twisted with one another, of which, viewed in cross section, at least two, in particular irregularly, are deformed flat, - have a first, larger diameter and a second, smaller diameter perpendicular to this, the ratio of which to one another is 1.10 to 3.00, - are embedded in the belt layer with their first, larger diameter lying largely flat and - to one another largely have the same clear distances, which are 0.10 mm to 1.00 mm.

Pneumatic vehicle tires with at least one belt layer designed in this way have a particularly good balance between the properties mentioned above. In pneumatic vehicle tires designed according to the invention, flat steel cords are embedded in at least one belt ply, preferably in all belt plies, and the small distance between them ensures high stability of the belt assembly. The particularly low layer thicknesses of the rubber layers cause a noticeable reduction in tire weight and therefore lower rolling resistance compared to tires with belt constructions with similar strength properties, but which are reinforced with steel cords made of a number of steel filaments with a circular cross section and embedded in the belt layers in any orientation. In pneumatic vehicle tires designed according to the invention, at least one of the belt layers, in particular all belt layers (with the exception of a possible belt bandage), is therefore reinforced with flattened steel cords. These flattened steel cords contain at least two steel filaments unevenly flattened or compressed into a non-circular shape. Depending on the point where a cross section is carried out, the steel cords therefore have two or more deformed steel filaments, it also being possible for all of the steel filaments to be deformed.

The deformation or compression preferably takes place in such a way that, viewed in any cross section along the steel cord, preferably at least one steel filament is circular in cross section, ie is not deformed at the relevant point. It is therefore not necessary for all of the steel filaments to be deformed or compressed in order to provide a “flat” steel cord.

In an embodiment of the steel cord with five steel filaments, preferably at least three, in an embodiment of the steel cord with six steel filaments, preferably at least four steel filaments are deformed, in particular irregularly, flat. The steel cords are therefore flattened overall in such a way that the belt ply reinforced with them has a particularly advantageous ratio of higher flexural rigidity in the lateral direction to lower flexural rigidity in the radial direction of the tire.

A configuration is particularly preferred in which, viewed in any cross section along the steel cord, exactly one of the steel filaments is circular when the steel cord is designed with five steel filaments, and exactly two steel filaments are circular when the steel cord is designed with four or six steel filaments.

In a further embodiment, the following relationship applies to the steel cords in the belt layer:

D ₁ = 100/epdm - R _g , where D ₁ is the larger diameter of the steel cord and D1 > 0.20 mm, in particular ≥ 0.26 mm, R _g is the mutual clearance between adjacent steel cords and epdm is the number of cords per 10 cm belt ply width. Such mutual coordination of these parameters is particularly advantageous in order to ensure high stability of the belt layer or the belt assembly and thus to ensure a long service life of the tire.

It is also of particular advantage if the ratio of the larger diameter to the smaller diameter of the steel cord is 1.20 to 1.90, in particular 1.40 to 1.80. This ratio is determined by the extent of the deformation of the original cord made of steel filaments with a circular cross-section, the specified diameter ratios yielding steel cords with high breaking strength, which also ensure high tensile strength of the belt ply.

Also particularly preferred is an embodiment of the belt ply in which the total layer thicknesses of the rubber layers are 0.20 mm up to 1.00 mm, in particular up to 0.70 mm and preferably up to 0.60 mm. The thinner the layer thicknesses of the rubber layers, the greater their beneficial effect on the overall weight of the tire and thus on the rolling resistance. Larger rubber layer thicknesses, which range in total from 0.50 mm to 1.00 mm, in special cases also up to 2.00 mm, are used in tires for trucks or buses, in tires for agricultural vehicles/machines, earthmoving machines and vehicles for material handling.

The layer thicknesses of the rubber layers can be the same or different, with their minimum thickness being at least 0.05 mm in each case. In this case, the radially outer layer thickness is preferably the greater in order to offer better protection against penetration by objects.

Furthermore, an embodiment of the pneumatic vehicle tire is particularly preferred in which at least one belt ply contains flattened steel cords made from five steel filaments, so that the steel content in the belt ply is relatively small, which is advantageous for the tire weight. In addition, can be reinforced with such steel cords Belt layers optimize the balance between the stability of the belt association and a low tire weight particularly well.

In the case of pneumatic vehicle tires for passenger cars, it is advantageous in this context if the belt layer contains flattened steel cords made of five steel filaments and with a larger diameter of 0.50 to 0.70 mm, the mutual clear distance between the steel cords being 0.35 mm to 0 is .70 mm. The ratio of the larger diameter of the steel cord to the smaller diameter of the steel cord, which, as already mentioned, is determined by the extent of the deformation, is preferably 1.40 to 1.60, in particular 1.50, for such steel cords.

In the case of pneumatic vehicle tires that are subject to greater loads during operation, such as pneumatic vehicle tires for heavy-duty vehicles, light trucks, buses and the like, it is preferred if the belt layer has flattened steel cords made of five steel filaments and with a larger diameter > 0.50 mm to 1.35 mm contains, the mutual clearance between the steel cords being 0.50 mm to 0.90 mm. In this variant, it is advantageous if the ratio of the larger diameter to the smaller diameter of the steel cord is 1.70 to 1.80.

The flattened steel cords are preferably produced by deforming steel cords made from steel filaments with a circular cross section and matching diameters of 0.18 mm to 0.45 mm, in particularly preferred embodiments by deforming steel cords made from steel filaments with a circular cross section and with diameters of 0.185 mm, 0. 20mm, 0.22mm, 0.28mm or 0.40mm.

In particularly preferred embodiments, the flattened steel cords are also produced by deforming steel cords from steel filaments that are circular in cross-section and have diameters of 0.18 mm to 0.45 mm, the relationship for the deformed, flattened steel cords being:

1.60 d ≤ D ₂ ≤ 2.40 d, where d is the diameter of the circular steel filaments of the undeformed steel cords and D ₂ is the smaller diameter of the deformed flattened steel cords. Further features, advantages and details of the invention will now be described in more detail with reference to the drawing, which shows exemplary embodiments. show it

1 shows a schematic cross section of an embodiment variant of a flattened steel cord made of five steel filaments,

2 shows a schematic cross-section of a non-flattened steel cord made of five steel filaments of circular cross-section

3 shows a schematic cross section of a further embodiment variant of a flattened steel cord made of six steel filaments,

4 shows a schematic cross section of a non-flattened steel cord made of six steel filaments with a circular cross section,

5 shows a realistic cross section of a flattened steel cord made of five steel filaments and

6 shows a schematic cross section of a section of a belt ply of a pneumatic vehicle tire with embedded, flattened and schematically illustrated steel cords made of five steel filaments.

The present invention deals with the arrangement of flattened, non-circular cross-section steel cords made of four to six steel filaments in at least one of the belt layers of pneumatic vehicle tires of radial design and any type, preferably tires for passenger cars, light trucks or heavy goods vehicles.

All dimensions given in the description are to be understood taking into account the usual deviations caused by production technology. The four to six steel filaments of the flattened steel cords are periodically twisted or twisted with one another so that an open steel cord is present such that the mixture material can penetrate into the gaps between the steel filaments when embedding the steel cords in a belt rubberizing mixture and fill them up. Individual steel filaments can also come into contact with one another without impairing the ability to penetrate. The steel filaments of the flattened steel cords have a usual tensile strength of 2,500 N/mm ² to 4,500 N/mm ² , the tensile strengths are therefore essentially in the range from NT (Normal Tensile) to UT (Ultra Tensile).

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 flattened steel cords 1 are produced in such a way that five or up to six identically shaped and im Cross-section circular steel filaments 2 'with a diameter d of 0.10 mm to 0.60 mm, in particular from 0.18 mm to 0.45 mm, twisted together, so that the in Fig. 2 and Fig. 4 round cross-section steel cords 1' arise as "origin cords". These "original cords" are deformed, for example by a rolling process, so that at least two steel filaments 2' are locally flattened or deformed, in particular in the area of their mutual contact points, and a cross-sectional shape that is at least partially irregularly flattened is obtained, with the steel cord 1 as a whole also being deformed a flattened cross-sectional shape. Due to the twisting of the steel filaments 2, viewed in different cross sections over the length of the steel cord 1, steel filaments 2 are deformed differently, some may not be deformed and then locally have their originally circular cross section. 5 shows this on the basis of a depiction 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 made of four steel filaments.

The flattened steel cords 1 have a larger diameter D ₁ and a diameter D ₂ which is smaller than D ₁ and is at right angles thereto. The diameters D ₁ and D ₂ are the largest diameters and are therefore at the Points with the greatest "widths" of the steel cords 1 determined. In this case, D ₁ > 0.2 mm, in particular D ₁ ≥ 0.26 mm, and the ratio of D ₁ to D 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 ₂ ≦2.40 d applies with regard to the smaller diameter D ₂ , where d is the diameter of the steel filaments, which are circular in cross section, of the undeformed steel cords. The deformation or compression of the “original cords” takes place in particular in such a way that the deformed steel filaments 2 have their largest diameter d ₁ essentially parallel to the diameter D ₁ and another smaller diameter d ₂ at their widest point at right angles to it, with the ratio of d ₂ to d ₁ ranges from about 0.70 to about 0.98.

The flattened deformed steel filaments 2 each have a cross-sectional area which corresponds or largely corresponds to that of the originally circular steel filaments 2, the latter because slight local material displacements can take place in the longitudinal direction of the steel filaments during the deformation process.

6 shows an example of a cross section through a section of a belt ply 3 of a pneumatic vehicle tire, the belt ply 3 being reinforced with steel cords 1 shown schematically with five steel filaments 2 . Instead of the steel cords made of five filaments shown, the belt layer 3 can also contain steel cords with four or six filaments, as described. The mutual clear distance R _g of the steel cords 1 depends on the diameter D ₁ and the cord density (epdm, number of cords per decimeter belt ply) and ranges from 0.10 mm, in particular 0.30 mm, to 1. 00 mm, where:

D ₁ = 100/epdm - R _g , where D ₁ > 0.2 mm as mentioned above.

If, according to a preferred embodiment, the flattened steel cords have five steel filaments and a diameter D ₁ of 0.50 mm to 0.70 mm, the mutual clear distance R _g between the steel cords is 0.35 mm to 0.70 mm. If the diameter D ₁ of the flattened steel cords is >0.50 mm to 1.35 mm, the Steel cords 1 embedded in the belt layer 3 in such a way that their mutual clear distance R _g is 0.50 mm to 0.90 mm.

The total thickness L _d of the belt ply 3 is the sum of the above-mentioned smaller diameter D ₂ of the steel cords 1 contained in the belt ply 3 and the layer thicknesses R _c and R _b of the topping rubber layers above and below the steel cords 1 . The layer thicknesses R _c and R _b are each determined as the smallest clear distances between the steel cords 1 and the outer or inner outer surfaces of the belt ply 3 . The sum of the two layer thicknesses R _c and R _b for flattened steel cords made from 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 to 0.60mm. R _c and R _b can be of the same size (on average) or of different sizes, resulting in an asymmetrical rubber coating. A preferred range for the sum of R _c and R _b is from 0.20 mm to 0.60 mm.

Table 1, Table 2 and Table 3 contain data on preferred embodiment variants VAR1.1, VAR1.2, VAR2.1, VAR 2.2, VAR3 and VAR 4 of belt layers with flattened steel cords 1 made from five steel filaments 2 and comparative examples REF1.1, REF1. 2, REF2 and REF3 of belt plies with steel cords, which are known steel cords implemented 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 comparison example to variant VAR3 and REF3 is the comparison example to variant VAR4.

The comparative examples REF1.1, REF1.2, REF2 and REF3 contain steel cords of the constructions 2 x 0.30 mm HT, 2 + 2 x 0.32 mm HT and 3 x 0.2 mm + 6 x 0.35 mm HT steel filaments circular in cross-section.

The steel cords in the belt layers (VAR1.1 to VAR4) designed according to the invention are flattened steel cords, with the originally circular diameter of the steel filaments being specified for the steel cord construction in the absence of better terminology. therefore 0.185mm (construction referred to as 5 x 1.85mm ST), further 0.20mm (construction referred to as 5 x 0.20mm ST), 0.28mm (construction referred to as 5 x 0.28mm ST). ) and 0.40mm (construction referred to as 5 x 0.40mm ST). Other parameters in the tables are the cord diameter (REF1.1 to REF3), the diameter D ₁ , the diameter D ₂ , the ratio D ₁ to D ₂ , the breaking strength of the respective steel cord, determined according to ASTM D2969 and ASTM D4975, the tensile strength of the Belt layer in kN/dm (calculated from the epdm and the breaking strength of the respective cord), the belt thickness in mm, the clear cord spacing R _g in mm and the number of cords per 10 cm belt layer (epdm).

In the comparative examples REF1.1 to REF3, the belt layer weight is set at 100%, in the examples VAR1.1 to VAR4 according to the invention it is given in % and in relation to the respective comparative example REF1.1 to REF3.

Table 1 Table 2

Table 3 reference number list

1, 1' steel cord

2, 2' steel filament 3 belt layer

R _g distance

R _c , R _b gum layer thicknesses

D ₁ , D ₂ Steel cord diameter d ₁ , d ₂ Steel filament diameter d Steel filament diameter

L _d total thickness of the belt ply

Claims

patent claims

1. Pneumatic vehicle tire with a belt assembly with at least one belt ply (3), which is reinforced with steel cords (1) embedded in rubber material, each having the same number of steel filaments (2), which - within each belt ply parallel to one another and under at least essentially the same size are arranged at mutual distances (R _g ),

- have rubber coating layers on both sides, the layer thicknesses (R _c , R _b ) totaling 0.10 mm to 2.00 mm, - viewed in cross section, are flattened open steel cords (1) made of four to six steel filaments (2) that are periodically twisted with one another, of which, viewed in cross-section, at least two are deformed flatly, in particular irregularly, - have a first, larger diameter and, perpendicularly thereto, a second, smaller diameter (D ₁ , D ₂ ), whose ratio (D ₁ /D ₂ ) to one another is 1 .10 to 3.00, - are embedded in the belt layer (3) with their first, larger diameter (D ₁ ) lying largely flat and - have largely equal clearances (R _g ) to one another, which are 0.10 mm to 1.00 mm.

2. Pneumatic vehicle tire according to claim 1, characterized in that viewed in any cross section along the steel cords (1), at least one steel filament (2) is circular in each case.

3. Pneumatic vehicle tire according to claim 1 or 2, characterized in that, viewed in any cross section along the steel cord (1), in an embodiment of the steel cord (1) with five steel filaments (2) at least three, with one Execution of the steel cord (1) with six steel filaments (2) at least four steel filaments (2), in particular irregularly, are deformed flat.

4. Pneumatic vehicle tire according to one of claims 1 to 3, characterized in that, viewed in any cross section along the steel cord (1), in an embodiment of the steel cord (1) with five steel filaments (2), exactly one of the steel filaments (2) is circular is, in an embodiment of the steel cord (1) with four or six steel filaments (2), exactly two steel filaments (2) are circular.

5. Pneumatic vehicle tire according to one of claims 1 to 4, characterized in that the following relationship applies to the steel cords (1) in the belt layer (3):

D ₁ = 100/epdm - R _g , where D ₁ is the larger diameter of the steel cords (1) and D1 > 0.20 mm, in particular ≥ 0.26 mm, and where

R _g is the mutual clearance between adjacent steel cords (1) and epdm is the number of cords per 10 cm belt ply width.

6. Pneumatic vehicle tire according to claim 1, characterized in that the ratio (D ₁ /D ₂ ) of the larger diameter (D ₁ ) to the smaller diameter (D ₂ ) of the steel cords (1) is 1.20 to 1.90, in particular 1. 40 to 1.80.

7. Pneumatic vehicle tire according to claim 1, characterized in that the layer thicknesses (R _c , R _b ) of the rubber coating layers total 0.20 mm to 1.00 mm. in particular up to 0.70 mm and preferably up to 0.60 mm.

8. Pneumatic vehicle tire according to claim 1 or 7, characterized in that the layer thicknesses (R _c , R _b ) of the rubber layers are the same size or different sizes, the layer thicknesses (R _c , R _b ) being at least 0.05 mm in each case.

9. Pneumatic vehicle tire according to one of claims 1 to 8, characterized in that the belt layer (3) contains flattened steel cords (1) made of five steel filaments (2).

10. Pneumatic vehicle tire according to one of claims 1 to 9, characterized in that the belt layer (3) flattened steel cords (1) made of five steel filaments (2) and with a larger diameter (D ₁ ) of 0.50 mm to 0.70 mm contains, the mutual clearance (R _g ) between the steel cords (1) being 0.35 mm to 0.70 mm.

11. Pneumatic vehicle tire according to claim 9 or 10, characterized in that the ratio (D ₁ / D ₂ ) of the larger diameter (D ₁ ) to the smaller diameter (D ₂ ) of the steel cords (1) is 1.40 to 1.60, in particular 1.5.

12. Pneumatic vehicle tire according to one of claims 1 to 9, characterized in that the belt layer (3) flattened steel cords (1) from five steel filaments (2) and with a larger diameter (D ₁ )> 0.50 mm to 1.35 mm contains, the mutual clearance (R _g ) between the steel cords (1) being 0.50 mm to 0.90 mm.

13. Pneumatic vehicle tire according to claim 9 or 12, characterized in that the ratio (D ₁ /D ₂ ) of the larger diameter (D ₁ ) to the smaller diameter (D ₂ ) of the steel cords (1) is 1.70 to 1.80.

14. Pneumatic vehicle tire according to one of Claims 1 to 13, characterized in that the flattened steel cords (1) are produced by deforming steel cords from steel filaments which are circular in cross-section and have the same diameters of 0.18 mm to 0.45 mm.

15. Pneumatic vehicle tire according to one of Claims 1 to 14, characterized in that the flattened steel cords (1) are formed by deforming steel cords made from steel filaments which are circular in cross-section and have diameters (d) of 0.185 mm, 0.20 mm, 0.22 mm, 0 .28 mm or 0.40 mm are manufactured.

16. Pneumatic vehicle tire according to one of claims 1 to 15, characterized in that the flattened steel cords (1) by deforming steel cords from im Cross-section circular steel filaments with diameters (d) of 0.18 mm to 0.45 mm are produced, where for the deformed, flattened steel cords (1) the relationship:

1.60 d≦D ₂ ≦2.40 d, where d is the diameter of the steel filaments, which are circular in cross section, of the undeformed steel cords and D ₂ is the smaller diameter of the deformed, flattened steel cords (1).