VEHICLE AIR TIRES

Description

[0001] The invention relates to a pneumatic vehicle tire of radial design with a footprint which is determined with a tire mounted on a standard rim at a load of 70% of the maximum load capacity and an internal pressure of 85% of the standard pressure according to ETRTO standards, and with a profiled tread with a tread shoulder outside the lateral footprint edges of the footprint, wherein the tread consists of at least one rubber material and wherein the tread contains inserts made of a rubber material which are stiffer than the other rubber material of the tread and which run circumferentially and extend to the tread periphery.

[0002] Such a pneumatic vehicle tire is known, for example, from WO 2019 / 016440 A1. This tire has a tread with a plurality of circumferential grooves running in the circumferential direction and tread elements located between them. Inserts with a trapezoidal cross-section are positioned in pairs within the tread such that their sidewalls each form a groove flank of a circumferential groove. The inserts have a stiffness that is greater than the stiffness of the rubber material of the tread. This is intended to improve the dynamic response of a vehicle equipped with such tires to steering forces without impairing the tire's rolling resistance or rolling noise.

[0003] US 2013 / 0220500 A1 discloses a commercial vehicle tire with a tread patterned with circumferential grooves. The tread has shoulder-side tread ribs, each containing an insert extending to the tread periphery. The inserts are made of a rubber material that is stiffer than the rest of the tread's rubber material. The inserts are located at least partially within the footprint and are intended to help prevent increased abrasion of the shoulder-side tread ribs compared to the rest of the tread.

[0004] FR 2 578 200 A1 discloses a commercial vehicle tire with a tread divided into three axial sections, such that the tread is composed of a central tread portion and two shoulder tread portions. The central tread portion is made of a rubber material with a JIS hardness of 63 to 67 and a tear strength of 240 kg / cm² to 280 kg / cm² to improve cut resistance. The shoulder tread portions are made of a rubber material with a JIS hardness of 58 to 62 and a tear strength of 280 kg / cm² to 320 kg / cm² and are said to exhibit good abrasion resistance.

[0005] JP S62 59104 A discloses a pneumatic vehicle tire with a tread having shoulder-side tread ribs, which are at least partially formed by shoulder-side tread parts. The shoulder-side tread parts extend to the tread periphery and help form the shoulder flanks extending to the sidewalls. According to one embodiment, the rubber material of the shoulder-side tread parts has a lower dynamic storage modulus than the rubber material of the remaining tread. The shoulder-side tread parts are therefore made of a rubber material that is less stiff than the rubber material of the remaining tread, with the shoulder-side tread parts contributing to uniform wear behavior of the tread.

[0006] EP 2 052 880 A1 discloses a pneumatic vehicle tire with a tread having a tread cap containing the tread pattern and a tread base, wherein the tread has, in at least one shoulder-side tread rib, a shoulder-side tread part made of the rubber material of the tread base, which part contacts the tread base and forms the tread outer surface. The rubber material of the shoulder-side tread part and the rubber material of the tread base are made of a rubber mixture containing 20 phr to 80 phr of carbon black and 10 phr to 40 phr of silica. The rubber material of the tread cap is made of a rubber mixture containing 40 phr to 100 phr of silica and 0 phr to 40 phr of carbon black. The rubber material of the shoulder-side tread parts has greater abrasion resistance than the rubber material of the tread cap.

[0007] When the tread of a tire enters the contact patch with the ground, pneumatic vehicle tires experience lateral compression, the extent of which depends on the stiffness of the rubber material in the tread that comes into contact with the ground. It is known that a softer rubber material in the tread is beneficial for good braking performance, but negatively impacts the tire's handling characteristics due to its low stiffness. In order to increase the stiffness in the shoulder-side tread elements, which are important for good handling characteristics, it is known to use stiffer rubber materials in these areas. This partially loses the beneficial effect of the softer rubber material in the tread.

[0008] The invention is based on the object of designing a tire of the type mentioned at the outset in such a way that the softer rubber material, which is advantageous for good braking performance of the tire, can be used over the entire area of ​​the tread that comes into contact with the ground without impairing the handling properties.

[0009] The stated object is achieved according to the invention in that an insert made of the stiffer rubber material is located outside the footprint, the rubber material of the inserts having a dynamic storage modulus E' mean which is 4 MPa to 8 MPa higher than that of the rubber material or rubber materials in the rest of the tread (1), E' mean being determined in accordance with DIN 53513 and E' being measured at 0.15% elongation and at 8% elongation, so that E' mean = [E'(0.15%) + E'(8%)] / 2 and the rubber material of the inserts having a Shore A hardness, determined in accordance with DIN ISO 7697-1, which is 5 Shore A to 15 Shore A, in particular 8 Shore A to 12 Shore A, higher than that of the rubber material or rubber materials in the rest of the tread.

[0010] The inserts provided according to the invention, which are preferably located completely outside the footprint and are made of a stiffer rubber material than the other rubber materials in the tread, surprisingly have such a stiffening effect despite their positioning that good handling characteristics are achieved. The area of ​​the tread that comes into contact with the ground can be made of a softer rubber compound, which is advantageous for braking properties.

[0011] For the stiffening effect of the inserts, it is beneficial if the inserts are directly connected to the footprint.

[0012] If the pneumatic vehicle tire has wing rubbers that adjoin the tread on the shoulder side, it is a further advantage if the inserts extend up to the wing rubbers.

[0013] In another preferred embodiment, the inserts are the only inserts in the tread whose rubber material is stiffer than the rest of the rubber material of the tread. The inserts may even be the only inserts in the tread. Therefore, the tread may advantageously consist of one or more rubber materials across the entire footprint area, each of which is designed for good braking performance.

[0014] For the stiffening effect of the inserts, it is also advantageous if they extend from the tread periphery to a depth which corresponds to 30% to 80% of the thickness of the tread at the zenith and if the inserts have a width of at least 3.0 mm, in particular from 5.0 mm to 12.0 mm, at the tread periphery.

[0015] For the stiffening effect of the inserts, it is further advantageous if they have a substantially parallelogram-shaped cross-section with two side walls running substantially parallel to one another, which run inclined towards the center of the tread and thus each enclose an angle of 5° to 35°, in particular up to 20°, in the radial direction.

[0016] The invention further relates to methods for producing a pneumatic vehicle tire according to one or more of claims 1 to 12. In preferred methods, the inserts are inserted as mixture strands into the unvulcanized tread, or they are co-extruded during the extrusion of the tread, or they are wound up during the construction of the tread by means of a strip-winding process.

[0017] Further features, advantages and details of the invention will now be described in more detail with reference to the drawing, which schematically shows an embodiment. The sole drawing figure shows, Fig. 1 , a partial cross-section through a pneumatic vehicle tire in the area of ​​the tread.

[0018] Fig. 1 shows a cross-section through a tread 1 of a pneumatic vehicle tire of radial design for passenger cars. The tread 1 is profiled and has, for example, circumferential grooves 2 and profile ribs 3 running between the circumferential grooves 2, which, as is known, can be divided into profile blocks. Radially inside the tread 1 is the not shown, for example two-layered belt assembly, which can additionally be covered with a belt bandage. B represents the footprint width, which is the largest width of the tread in the ground contact area and is determined with a tire mounted on a standard rim at a load of 70% of the maximum load capacity and an internal pressure of 85% of the standard pressure (standard rim, standard pressure, load capacity according to ETRTO standards).The axially outermost edges of the footprint run parallel to the circumferential direction of the tire and are referred to as footprint edges k. Outside the footprint edges k, the tread 1 has a section in both of its side areas, each of which forms a tread shoulder 4. In each tread shoulder 4, in the embodiment shown, outside the footprint width B and immediately adjacent to the associated footprint edges k, there is a rib- or strip-shaped insert 5 running around the circumference of the tread and made of a rubber material which differs from the surrounding rubber material(s) in the tread 1 in that it has a higher dynamic storage modulus E' mean and a higher Shore A hardness.The dynamic storage modulus E' mean is determined using a vulcanized sample at 55°C from a dynamic-mechanical measurement according to DIN 53513. E' is measured at 0.15% elongation and E' at 8% elongation, so that E' mean = [E'(0.15%) + E'(8%)] / 2. The Shore A hardness is also determined using a sample in the vulcanized state at room temperature according to DIN ISO 7697-1. The dynamic storage modulus E' mean of the rubber material of inserts 5 is 4 MPa to 8 MPa higher than that of the rubber material(s) in the rest of tread 1. The Shore A hardness of inserts 5 is 5 Shore A to 15 Shore A, in particular 8 Shore A to 12 Shore A, higher than that of the rubber material(s) in tread 1.

[0019] At the Fig. 1 In the preferred embodiment shown, each insert 5 is parallelogram-shaped or substantially parallelogram-shaped in cross-section with two side walls 5a running parallel to one another or substantially parallel to one another, which, with respect to the respective tread shoulder 4, run inclined towards the center of the tread 1 and thus each enclose an acute angle α of 5° to 35°, in particular up to 20°, with the radial direction, which is indicated by dashed lines. The inserts 5 have a width b, which is measured at the tread periphery in the axial direction and is at least 3.0 mm and in particular 5.0 mm to 12.0 mm. The inserts 5 further extend to a depth t, which corresponds to 30% to 80% of the thickness d of the tread 1 at the zenith. The thickness d is determined in the radial direction and starting from an envelope at the tread periphery. In Fig. 1Wing rubbers 6 are indicated on the shoulder side of the tread 1, which, as is known, extend toward the sidewall rubbers and overlap with them. In an alternative design, the inserts 5 extend to the wing rubbers 6.

[0020] In further embodiments not shown, the inserts 5 have other cross-sectional shapes, for example V-shaped or triangular, with the triangle widening towards the tread periphery.

[0021] The insertion of the inserts 5 can be carried out by inserting appropriately shaped mixture strands into the unvulcanized tread, by appropriate extrusion of the tread - together with the inserts - or by producing the tread by means of a strip-winding process. List of reference numbers

[0022] 1Tread 2Circumferential groove 3Tread rib 4Tread shoulder 5Insert 6Wing rubber BFootprint width bWidth dThickness kFootprint edge tDepth αAngle

Claims

1. Pneumatic vehicle tyre of a radial design with a footprint that is determined with a tyre mounted on a standard rim under a load of 70% of the maximum load-bearing capacity and an internal pressure of 85% of the standard pressure in accordance with E.T.R.T.O. standards and with a profiled tread (1) with a tread shoulder (4) outside each of the side footprint edges (k) of the footprint, wherein the tread (1) consists of at least one rubber material and wherein the tread (1) contains inserts (5) which run around in the circumferential direction, reach as far as the tread periphery and are made of a rubber material that is stiffer than the other rubber material of the tread (1), characterized in that an insert (5) made of the stiffer rubber material is situated outside the footprint on each side, wherein the rubber material of the inserts (5) has a dynamic storage modulus E' mean which is 4 MPa to 8 MPa higher than that of the rubber material or the rubber materials in the rest of the tread (1), wherein E' mean is determined in accordance with DIN 53513 and E' is measured under 0.15% elongation and under 8% elongation, so that E' mean = [E'(0.15%) +E'(8%)] / 2, and wherein the rubber material of the inserts (5) has a Shore A hardness, determined in accordance with DIN ISO 7697-1, which is 5 Shore A to 15 Shore A, in particular 8 Shore A to 12 Shore A, higher than that of the rubber material or the rubber materials in the rest of the tread (1).

2. Pneumatic vehicle tyre according to Claim 1, characterized in that the inserts (5) directly adjoin the footprint.

3. Pneumatic vehicle tyre with wing rubbers (6) adjoining the tread (1) at the shoulders, according to Claim 1 or 2, characterized in that the inserts (5) reach as far as the wing rubbers (6).

4. Pneumatic vehicle tyre according to one of Claims 1 to 3, characterized in that the inserts (5) are the only inserts (5) in the tread (1) of a stiffer rubber material than the other rubber material of the tread (1).

5. Pneumatic vehicle tyre according to one of Claims 1 to 4, characterized in that, taken from the tread periphery, the inserts (5) reach to a depth (t) which corresponds to 30% to 80% of the thickness (d) of the tread (1) at the crown.

6. Pneumatic vehicle tyre according to one of Claims 1 to 5, characterized in that the inserts (5) have at the tread periphery a width (b) of at least 3.0 mm, in particular of 5.0 mm to 12.0 mm.

7. Pneumatic vehicle tyre according to one of Claims 1 to 6, characterized in that the inserts (5) have a substantially parallelogram-shaped cross section with two side walls (5a) running substantially parallel to one another, which extend in an inclined manner in the direction of the middle of the tread (1) and in each case include an angle (α) of 5° to 35°, in particular to 20°, with the radial direction.

8. Pneumatic vehicle tyre according to one of Claims 1 to 7, characterized in that the inserts (5) are the only inserts in the tread (1).

9. Method for producing a pneumatic vehicle tyre according to one or more of Claims 1 to 8, characterized in that the inserts (5) are inserted into the unvulcanized tread as strands of extruded mixture.

10. Method for producing a pneumatic vehicle tyre according to one or more of Claims 1 to 8, characterized in that the inserts (5) are co-extruded during the extrusion of the tread.

11. Method for producing a pneumatic vehicle tyre according to one or more of Claims 1 to 8, characterized in that the inserts (5) are wound on by means of a strip winding process during the build-up of the tread.