DE102011001877B4 - pneumatic vehicle tires - Google Patents

Abstract

Pneumatic vehicle tire with a belt (2) and a tread (1), which consists of a radially inner first rubber layer (base) (4) covering the belt (2) and a radially outer second rubber layer (cap) (5) forming the road contact surface, wherein the first rubber layer (base) (4) has an electrically conductive rubber mixture from which an electrically conductive rubber wedge (6) is also formed and wherein this rubber wedge (6) completely penetrates the second rubber layer (cap) (5) in the radial direction, wherein the first rubber layer (base) (4) is formed in at least two parts in the axial direction, wherein it consists of at least a first layer part (7) made of a rolling resistance-optimized rubber mixture and a second layer part (8) made of the electrically conductive rubber mixture, wherein the second layer part (8), viewed in the tire cross-section, is arranged axially on the outside, characterized in that the first rubber layer (Base) (4) is formed in two parts, wherein the second layer part (8) has a width (10) of 20% - 40% of the axial width (9) of the first rubber layer (Base) (4).

Description

The invention relates to a pneumatic vehicle tire with a belt and a tread, which consists of a radially inner first rubber layer (base) covering the belt and a radially outer second rubber layer (cap) forming the road contact surface, wherein the first rubber layer (base) has an electrically conductive rubber mixture from which an electrically conductive rubber wedge is also formed and wherein this rubber wedge completely penetrates the second rubber layer (cap) in the radial direction, wherein the first rubber layer (base) is formed in at least two parts in the axial direction, wherein it consists of at least a first layer part made of a rolling resistance-optimized rubber mixture and a second layer part made of the electrically conductive rubber mixture, wherein the second layer part, viewed in the tire cross-section, is arranged axially on the outside and the first rubber layer (base) is formed in two parts, wherein the second layer part has a width of 20% - 40% of the axial width of the first rubber layer (base).

Such pneumatic vehicle tires with a belt and a tread made up of a radially inner first rubber layer (base) covering the belt and a radially outer second rubber layer (cap) forming the road contact surface are widely used. The second rubber layer (cap) forming the road contact surface usually has a high silica content for good driving properties and is insufficiently electrically conductive, while the first rubber layer (base) is usually carbon black-based and has sufficient electrical conductivity. In order to be able to dissipate the electrostatic charge of the tire via the tread independently of the rubber mixture of the cap, an electrically conductive rubber wedge, which consists of the rubber material of the base and is connected to it, is arranged within the ground contact area of the tread. This rubber wedge penetrates the second rubber layer (cap) completely in approximately the radial direction and is in contact with the road surface.

A pneumatic vehicle tire of the type mentioned above is known, for example, from US 2009/0095390 A1 known. The tire has a belt and a tread made of a cap made of electrically non-conductive rubber material and a one-piece base made of electrically conductive rubber material. The cap is penetrated in the middle by an electrically conductive rubber wedge that is in contact with the base and runs around the circumference in the radial direction. The wedge is made of the same rubber material as the base. To produce the tread, according to one embodiment, a rubber mixture strip made of electrically conductive base mixture is wound up and a right-hand section of a base is formed in this way. A rubber mixture strip made of electrically non-conductive cap mixture is wound up on the radial outside of the right-hand section of the base, thereby forming a right-hand section of a cap. A left-hand section of the base is then formed from the rubber mixture strip made of the base mixture, with a web running to the tread periphery being formed in the middle of the tread. A rubber mixture strip made of cap mixture is wound onto the radial outside of the left section of the base, forming a left section of the cap which ends at the web and does not overlap it radially on the outside. The method is intended to allow a safe manufacture of the corresponding pneumatic vehicle tire, in particular a reliable formation of the corresponding rubber wedge. In the associated tire, the rubber wedge is to be securely supported and yet narrow, so that stable and precise positioning in the tread is possible during manufacture with a narrow contact area to the road surface.

The JP 2010 222 004 A discloses a pneumatic vehicle tire with a tread made of a cap and a base, each of which consists of electrically non-conductive rubber material. An electrically conductive rubber layer runs between the cap and the base in one half of the tread, which extends to the outer surface of the tread in the area of the tire's equatorial plane. A method for producing the tread is also disclosed. In this method, reinforcement strips are applied to a building drum to form the belt layers. A rubber mixture strip is wound onto the reinforcement strips to form the base. A first cap section made of an electrically non-conductive rubber mixture strip is then wound over approximately half of the base, and then an electrically conductive rubber mixture strip is wound onto the section of the base that is not yet covered to form the rubber layer, with the rubber mixture strip running over part of the first cap section to the periphery. A second cap section is then wound on, completing the cap in this way, leaving the radially outer end of the rubber mixture strip that subsequently forms the rubber layer free. During vulcanization, care must be taken to ensure that the rubber layer that is being formed actually reaches the tread periphery. This is ensured by the formation of a protrusion on the tread periphery. The associated vulcanization mold or the corresponding mold segment must be specially designed or constructed. The electrically conductive passage formed from the rubber layer The tread periphery should be as narrow as possible, which is beneficial for rolling resistance and wet grip.

Tire development is striving to make pneumatic vehicle tires with lower rolling resistance. It is known that a pneumatic vehicle tire has a higher rolling resistance when using carbon black-based, electrically conductive rubber mixtures. Nevertheless, a carbon black-based rubber mixture is necessary for the base in order to conduct the electrical charge from an appropriately designed belt or sidewall and to dissipate it through the rubber wedge through the tread.

The invention is based on the object of providing a pneumatic vehicle tire with optimized rolling resistance with respect to the tread and a method for producing this tread.

The problem is solved by the first rubber layer (base) being divided into two parts, with the second layer part having a width of 20% - 40% of the axial width of the first rubber layer (base).

According to the invention, the first rubber layer (base) is designed in at least two parts to improve the rolling resistance of the pneumatic vehicle tire, i.e. it consists of at least two layer parts, one of which is made of a rubber mixture optimized for rolling resistance. The other layer part is sufficiently electrically conductive for the necessary dissipation of the electrical charge and preferably consists of a carbon black-based rubber mixture. The rubber wedge originates from the layer part of the carbon black-based rubber mixture and completely penetrates the cap in an approximately radial direction and is in contact with the road surface. This improves the rolling resistance of the pneumatic vehicle tire, while the dissipation of the electrical charge is still reliably guaranteed.

The smaller width value is obtained when the second layer part extends in the right or left half of the tread cross-section from the shoulder area to between two circumferential profile grooves, and the maximum value is obtained when the layer part extends from the shoulder area to the outermost circumferential groove of the tire, but in any case still within the ground contact width. The second layer part is arranged axially on the outside in the tire cross-section. It is important that the electrically conductive rubber wedge extends within the ground contact area of the pneumatic vehicle tire within a profile element in order to be able to come into contact with the road surface.

• 1 einen Fahrzeugluftreifen in Querschnittsdarstellung;
• 2 die rechte Querschnittshälfte durch den Laufstreifen eines Reifenrohlings;
• 3 die rechte Querschnittshälfte durch einen anderen Laufstreifen eines Reifenrohlings;
• 4 die rechte Querschnittshälfte durch einen weiteren Laufstreifen eines Reifenrohlings.

Further features, advantages and details of the invention will now be explained in more detail with reference to the drawings, which show schematic embodiments. The drawing shows:

• 1 a vehicle pneumatic tire in cross-section;
• 2 the right half of the cross-section through the tread of a green tire;
• 3 the right half of the cross-section through another tread of a green tire;
• 4 the right half of the cross-section through another tread of a green tire.

In 1 the structure of the pneumatic vehicle tire according to the invention is shown by way of example. In the pneumatic vehicle tire, in a right bead region 22 designed to attach the pneumatic vehicle tire to a rim, around a bead core 23 with a core profile not shown in detail, a carcass ply of a carcass 3 of radial design is laid outside an air-impermeable inner layer over the right shoulder region and the zenith plane to the left shoulder region and the bead core 23 with core profile formed in the left bead region 22, around which it runs in the conventional manner. In the conventional manner, a bead strip of a known type (not shown in detail), a bead reinforcement of a known type (not shown in detail) and a horn profile 26 are formed in the bead region 22, and a sidewall rubber material 24 is laid on, starting from the horn profile 26 and extending into the shoulder region. Several belt layers of a belt 2 with steel cords embedded in rubber extend over the circumference of the tire outside the carcass 3. A belt bandage layer of a known type with strength members oriented in the circumferential direction is formed on the belt layers of the belt 2 between the belt layers 2 and the tread 1. In the shoulder area, additional shoulder strips 25 are applied in a known manner. The tire structure is completed in a known manner by a profiled tread 1.

The tread 1 consists of a radially inner first rubber layer (base) 4 covering the belt 2, a radially outer second rubber layer (cap) 5 forming the road contact surface and an electrically conductive rubber wedge 6 which completely penetrates the second rubber layer (cap) 5 in approximately the radial direction (R) and has contact with the road surface. The first rubber layer (base) 4 is divided into two parts, so that it has a first layer part 7, which consists of a rolling resistance-optimized rubber mixture, and a second layer part 8, which consists of the electrically conductive rubber mixture. The rubber wedge 6 consists of the material of the second layer part 8 and is in connection with it. The rubber wedge 6 is arranged radially above the first layer part 7. The second layer part 8 has an axial width 10 of 20% - 40% of the axial width 9 of the first rubber layer (base) 4. The rubber wedge 6 arranged radially above the rolling resistance-optimized first layer part 7 is not included in the axial width 10 of the second layer part 8. The second rubber layer (cap) 5 forming the road surface contract surface has a high silica content for good driving properties and is insufficiently electrically conductive.

• Man bildet die erste Kautschuklage (Base) (4) wenigstens 2-geteilt aus, indem man ein erstes Lagenteil 7, welches aus einer rollwiderstandsoptimierten Kautschukmischung besteht und indem man ein zweites Lagenteil 8, welches aus einer elektrisch leitfähigen Kautschukmischung besteht, auf den Gürtel (nicht dargestellt) auflegt. Weiterhin sieht man innerhalb des zweiten Lagenteils 7 eine Materialanhäufung 6 dort vor, wo der elektrisch leitfähige Kautschukkeil 6 ausgebildet werden soll. Anschließend bringt man die zweite Kautschuklage (Cap) 5 auf. Die zweite Kautschuklage (Cap) 5 führt man profiliert aus, derart, dass die Dicke der zweiten Kautschuklage 5 radial oberhalb der Materialanhäufung 6 soweit verringert ist, dass während des Heiz-Pressvorganges des Reifenrohlings die Materialanhäufung 6 die zweite Kautschuklage 5 vollständig durchstößt und den Kautschukkeil 6 bildet. Im unvulkanisierten Zustand überdeckt die zweite Kautschuklage (Cap) 5 die 2-geteilte erste Kautschuklage (Base) 4 samt Materialanhäufung 6 vollständig. Die Materialanhäufung 6 überlappt das dem zweiten Lagenteil 8 zugewandte Ende des ersten Lagenteils 7.

The 2 shows the right half of the cross-section through the tread 1 of a green tire, which in the vulcanized state represents a section of the tire of the 1 To produce the tread 1 including the material accumulation 6, proceed as follows:

• The first rubber layer (base) (4) is formed in at least two parts by placing a first layer part 7, which consists of a rubber mixture optimized for rolling resistance, and a second layer part 8, which consists of an electrically conductive rubber mixture, on the belt (not shown). Furthermore, a material accumulation 6 is provided within the second layer part 7 where the electrically conductive rubber wedge 6 is to be formed. The second rubber layer (cap) 5 is then applied. The second rubber layer (cap) 5 is profiled in such a way that the thickness of the second rubber layer 5 radially above the material accumulation 6 is reduced to such an extent that during the heating-pressing process of the green tire, the material accumulation 6 completely penetrates the second rubber layer 5 and forms the rubber wedge 6. In the unvulcanized state, the second rubber layer (cap) 5 completely covers the two-part first rubber layer (base) 4 including the material accumulation 6. The material accumulation 6 overlaps the end of the first layer part 7 facing the second layer part 8.

The 3 shows the right half of the cross-section through another tread 1 of a green tire. This other tread 3 differs from the tread of the 2 in that the first layer part 7 is arranged abutting against the second layer part 8. The material accumulation 6 is arranged in the edge region of the second layer part 8. In the vulcanized tire, the rubber wedge 6 is not arranged radially above, but laterally adjacent to the first layer part 7.

The 4 shows the right half of the cross-section through another tread 1 of a green tire. The difference to 2 is that the first layer part 7 extends thinned below the overlap width and that the overlapping layer part 8 is made correspondingly thinner, so that the thickness of the first rubber layer (base) is approximately the same within its axial extension.

list of reference symbols

1

tread

2

Belt

3

carcass

4

base

5

cap

6

Electrically conductive rubber wedge / material accumulation

7

First layer part (rolling resistance optimized)

8

Second layer part (electrically conductive)

9

Axial width of the base

10

Axial width of the second layer part

22

bead area

23

bead core

24

sidewall rubber material

25

shoulder stripes

26

horn profile

R

radial direction

A

axial direction

Claims (1)

Pneumatic vehicle tire with a belt (2) and a tread (1), which consists of a radially inner first rubber layer (base) (4) covering the belt (2) and a radially outer second rubber layer (cap) (5) forming the road contact surface, wherein the first rubber layer (base) (4) has an electrically conductive rubber mixture from which an electrically conductive rubber wedge (6) is also formed and wherein this rubber wedge (6) completely penetrates the second rubber layer (cap) (5) in the radial direction, wherein the first rubber layer (base) (4) is formed in at least two parts in the axial direction, wherein it consists of at least a first layer part (7) made of a rolling resistance-optimized rubber mixture and a second layer part (8) made of the electrically conductive rubber mixture, wherein the second layer part (8), viewed in the tire cross-section, is arranged axially on the outside, characterized in that the first rubber layer (Base) (4) is divided into 2 parts, wherein the second layer part (8) has a width (10) of 20% - 40% of the axial width (9) of the first rubber layer (base) (4).

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