Commercial vehicle tires

Abstract

Commercial vehicle tire of radial construction with a tread (1), a carcass ply (3) and a belt assembly (2) consisting of at least four belt plies (6 to 10), wherein the belt ply located in the position of the second or third belt ply is a 0° belt ply (8) having a width (b1) of 70% to 90% of the ground contact area width (B) and consisting of a steel cord (11) wound in a single layer in a spiral fashion with circumferentially circumferential turns, wherein the further belt plies (6, 7, 9, 10) each have steel cords running parallel to each other and at an acute angle to the circumferential direction, embedded in a rubber ply, characterized in that the 0° belt ply (8) has lateral sections (8b, 8'b) in which the steel cord turns are directly on the belt ply (6) arranged radially within the 0° belt ply (8). 7) are located,wherein the steel cord windings in the areas of the 0° belt layer (8) adjoining the lateral sections (8b, 8'b) are located on a separate thin rubber layer (12, 13) which is positioned between the belt layer (6, 7) arranged radially within the 0° belt layer (8) and the 0° belt layer (8).

Description

The invention relates to a commercial vehicle tire of radial construction with a tread, a carcass insert and a belt assembly of at least four belt layers, wherein the belt layer located in the position of the second or third belt layer is a 0° belt layer, which has a width of 70% to 90% of the ground contact area width and consists of a steel cord which is wound in a single layer in a spiral fashion from edge edge to edge edge in circumferential turns, wherein the further belt layers each have steel cords running parallel to each other and at an acute angle to the circumferential direction, embedded in a rubber layer. It is known to incorporate a 0° belt layer in the belt structure of commercial vehicle tires, consisting of a steel cord wound spirally around the circumference of the tire. 0° belt layers in the belt structure are advantageous for the circumferential stiffness of the commercial vehicle tire, more uniform or reduced tread wear, and overall increased durability of the belt structure. Uniform and, if possible, high circumferential stiffness across the tread width is one of the parameters responsible for low tread wear. One of the factors influencing the circumferential stiffness achievable with a 0° belt layer is the preload applied to the steel cord during the winding process. This winding process begins at one edge of the 0° belt layer to be created and continues continuously across the axial width in the circumferential direction of the tread until the second edge of the 0° belt layer is reached.In the outer windings, the original pretension is no longer maintained due to the loose ends of the steel cord located there; in particular, part of this pretension is lost during the crowning process of the raw tire. Commercial vehicle tires of the type mentioned above with a 0° belt layer are known in a variety of designs, also from patent literature. A commercial vehicle tire of the type mentioned above is known, for example, from EP 1 886 843 B1. This commercial vehicle tire has a belt structure with four belt plies. The first belt ply has steel cords running at an angle of 10° to 45° to the circumferential direction and has an axial width of at least 85% of the width of the contact patch. The third belt ply has steel cords running at an angle of 10° to 45° to the circumferential direction and in the opposite direction to the steel cords of the first belt ply, and has an axial width of at least 85% of the width of the contact patch. The second belt ply is a 0° belt ply with steel cords running at an angle of up to 5° to the circumferential direction and has an axial width of at least 70% of the contact patch, being narrower than the first and third belt plies.The fourth belt layer features steel cords running at an angle of up to 5° to the circumferential direction and has an axial width of 35% to 40% of the contact patch. Between the first and third belt layers, an axially inner rubber layer with a thickness of 1.5 mm to 4.0 mm and an axially outer rubber layer with a thickness of at least 2.0 mm are formed, adjoining each belt edge of the second belt layer. The rubber material of the axially inner layer has a complex modulus of elasticity of 8.0 MPa to 14.0 MPa, and the rubber material of the axially outer layer has a complex modulus of elasticity of 6.0 MPa to 12.0 MPa. These measures are intended to limit the expansion of the commercial vehicle tire during driving. For example, EP 1 754 615 B1 discloses a commercial vehicle tire with a belt structure comprising at least three belt layers, the second belt layer being a 0° belt layer. DE 10 2010 000 181 A1 discloses a commercial vehicle tire with a belt structure comprising at least four belt layers, in which the second belt layer is also a 0° belt layer. In the commercial vehicle tire disclosed in DE 10 2014 209 423, with a belt structure comprising at least four layers and using steel cords as reinforcing elements, the first belt layer is a 0° belt layer. The invention is based on the objective of designing a commercial vehicle tire of the type mentioned above in such a way that the lower preload caused by the loose ends of the steel cord in the edge sections of the 0° belt layer is no longer present; preferably, the preload in the edge sections of the 0° belt layer should even be higher than in the middle area of ​​the 0° belt layer. The object stated is solved according to the invention by the fact that the 0° belt layer has lateral sections in which the steel cord windings are located directly on the belt layer arranged radially within the 0° belt layer, wherein the steel cord windings in the areas of the 0° belt layer adjoining the lateral sections are located on a separate thin rubber layer which is positioned between the belt layer arranged radially within the 0° belt layer and the 0° belt layer. In a commercial vehicle tire according to the invention, the steel cord windings located in the outer sections of the 0° belt layer therefore have a shorter circumferential length than those located in the adjacent areas of the 0° belt layer. Consequently, during the crowning process, a greater tension is applied to the raw tire in the lateral sections of the 0° belt layer than in those areas where steel cord windings are positioned on a rubber layer. As a result, in a tire designed according to the invention, the pretension of the steel cords in the 0° belt layer can be essentially the same in the lateral areas as in the other areas of this belt layer. The finished tire can therefore exhibit the desired uniform circumferential stiffness across its width in the tread area. As mentioned earlier, uniform circumferential stiffness is particularly advantageous for uniform tread wear. In a preferred embodiment of the invention, the lateral sections of the 0° belt layer have an axial width of 5% to 15% of the width of the 0° belt layer. Lateral sections of this width are particularly well suited for achieving uniform circumferential stiffness. A particularly advantageous embodiment of the invention is one in which the rubber layer extends continuously between the lateral sections of the 0° belt layer. A tire with a continuous rubber layer can be manufactured easily. In a design favorable to the rolling resistance of the tire, two rubber layers with an axial width of 10% to 20% of the width of the 0° belt layer are present, with the 0° belt layer being located directly on the belt layer arranged radially inside the 0° belt layer in the area between the rubber layers. The desired effect can be optimally achieved with one or two layers of rubber, which have a substantially constant thickness of 1 mm to 2 mm. Further features, advantages, and details of the invention will now be described in more detail with reference to the drawing, which schematically illustrates exemplary embodiments. Figures 1 and 2 show cross-sections through the radially outer region of a commercial vehicle tire, each depicting a variant of the invention. All dimensions specified in the description and in the patent claims refer to the vulcanized, unmounted tire. Figures 1 and 2 show the essential components of a radial-type commercial vehicle tire: a tread 1, a belt 2, a carcass ply 3, an airtight inner layer 4, and the radially outer sections of sidewalls 5. The carcass ply 3, the inner layer 4, the tread 1, and the other tire components not shown can be designed in a manner known per se. In Figures 1 and 2, the contact patch width of the tread 1 is also denoted by B. The belt assembly 2, located between the tread 1 and the carcass insert 3, has five belt layers 6, 7, 8, 9, and 10 in the illustrated embodiments. The fifth, radially outermost belt layer 10 is usually referred to as the protective layer and has the narrowest width of all belt layers 6 to 10. The first, radially innermost belt layer 6 is the so-called barrier layer; the second belt layer 7 and the fourth belt layer 9 are the so-called working layers and are subsequently referred to as such. The working layers 7 and 9 are wider than the radially innermost and the radially outermost belt layers 6 and 10, with the more radially inner working layer 7 being wider than the second working layer 9. Between the two working layers 7 and 9, there is a third belt layer, a 0° belt layer 8. The belt layers 6, 7, 9, and 10 each consist of steel cords of conventional construction embedded in a belt rubber layer, the steel cords in each belt layer 6, 7, 9, and 10 running essentially parallel to one another at the usual intervals. The steel cords in the belt layers 6, 7, 9, and 10 also run at the usual angles to the circumferential direction of the tire, which may differ in the individual belt layers 6, 7, 9, and 10, with the angles being selected, in particular, in a range of 10° to 75°. The mutual arrangement of the steel cords in some or all belt layers 6, 7, 9, and 10 is, in particular, such that the steel cords cross each other in a manner known per se. The actual arrangement of the steel cords in these belt layers 6, 7, 9, and 10 is not the subject of the invention and can be carried out according to the prior art. The previously mentioned 0° belt layer 8 has a width b1 of 70% to 90% of the width B and consists of a multitude of adjacent and parallel turns of a single circumferentially wound steel cord 11. The steel cord turns therefore run almost circumferentially; they can deviate from this by up to an angle of 5°. In the embodiment shown in Fig. 1, an additional thin rubber layer 12 is arranged symmetrically to the equatorial plane of the tire on the working position 7, the width of which b2 is 70% to 90% of the width b1 of the 0° belt layer 8. The 0° belt layer 8 therefore has a central section 8a, which is located on the rubber layer 12 and whose width corresponds to the width b2 of the rubber layer 12, and two lateral sections 8b, which are located directly on the working layer 7 and each have a width b4 of 5% to 15% of the width b1 of the 0° belt layer 8. During tire or belt construction, the 0° belt layer 8 is created by spirally winding the steel cord 11 circumferentially, starting at the edge of one lateral section 8b, winding this section 8b, winding section 8a on the still unvulcanized compound layer for the rubber layer 12, and winding the second lateral section 8a. In the vulcanized tire, the rubber layer 12 has a substantially constant thickness of 1.0 mm to 2.0 mm. The rubber layer 12 is preferably based on a rubber compound that corresponds to the rubber compound of the belt rubbers. In the embodiment shown in Fig. 2, two narrow rubber layers 13 are located directly on the working layer 7 within the area of ​​width b2, which is 70% to 90% of the width b1 of the 0° belt layer 8, and each directly adjoining one of the lateral edges of this area. The rubber layers 13 also have a thickness of 1.0 mm to 2.0 mm, and their width b3 is each 10% to 20% of the width b1 of the 0° belt layer 8. The 0° belt layer 8 therefore has two lateral sections 8'b with a width b4, which are located directly on the working layer 7, two intermediate sections 8'c, which are located on each of the rubber layers 13, and between the rubber layers 13 a central section 8'a, which is again located directly on the working layer 7. The circumferential length of the turns of the steel cord in the 0° belt position 8 is less in the lateral sections 8b, 8'b than in the section 8a ( Fig. 1 ) or the sections 8'c ( Fig. 2 ), which are located on a rubber layer 12, 13. During the construction of the raw tire, the 0° belt layer 8 is wound spirally onto a construction drum onto the already applied working layer 7 and onto the rubber compound web for the rubber layer 12 positioned on this, or onto the rubber compound strips for the rubber layers 13 positioned on this. The raw tire, along with the belt assembly, is then cambered, whereby the steel cord windings in the 0° belt layer 8 are subjected to elongation. Since the circumferential length of the steel cord windings in the lateral sections 8b, 8'b is shorter than in those located on a rubber layer 12, 13, the increase in tension in the steel cord windings in the lateral sections 8b, 8'b due to the cambering process is greater than in the steel cord windings located on rubber layers 12, 13. In this way, the lower pretension of the steel cord present in the lateral areas of 0° belt layers, caused by the loose ends of the steel cord located there, can be compensated for. In tires designed according to the invention, it is therefore possible to achieve both a uniform pretension of the steel cord windings across the entire width of the 0° belt layer 8 and, in principle, to influence the stress distribution and thus the circumferential stiffness of the vulcanized tire. In particular, in a commercial vehicle tire according to the invention, the circumferential stiffness in the lateral areas of the tread can be greater than in the central area due to a higher pretension of the steel cord windings in the lateral areas of the 0° belt layer. In a further embodiment of the invention, not shown, the 0° belt layer can be located between the first belt layer and the radially inner working layer, with the rubber layer(s) being located on the first belt layer in this case. Furthermore, the belt assembly can comprise a total of four belt layers, in particular a barrier layer, a 0° belt layer, and two working layers. Reference number list 1 Tread 2 Belt bandage 3 Carcass insert 4 Inner layer 5 Sidewall 6, 7, 9, 10 Belt layer 8 0° belt layer 8a, 8'a, 8b, 8'b Section 8'c Intermediate section 11 Steel cord 12, 13 Rubber layer B Ground contact area width b1, b2, b3, b4 Width

Claims

Commercial vehicle tire of radial construction with a tread (1), a carcass ply (3) and a belt assembly (2) consisting of at least four belt plies (6 to 10), wherein the belt ply located in the position of the second or third belt ply is a 0° belt ply (8) having a width (b1) of 70% to 90% of the ground contact area width (B) and consisting of a steel cord (11) wound in a single layer in a spiral fashion with circumferentially circumferential turns, wherein the further belt plies (6, 7, 9, 10) each have steel cords running parallel to each other and at an acute angle to the circumferential direction, embedded in a rubber ply, characterized in that the 0° belt ply (8) has lateral sections (8b, 8'b) in which the steel cord turns are directly on the belt ply arranged radially within the 0° belt ply (8). (6, 7) are located,wherein the steel cord windings in the areas of the 0° belt layer (8) adjoining the lateral sections (8b, 8'b) are located on a separate thin rubber layer (12, 13) which is positioned between the belt layer (6, 7) arranged radially within the 0° belt layer (8) and the 0° belt layer (8). Commercial vehicle tires according to claim 1, characterized in that the lateral sections (8b, 8'b) of the 0° belt layer (8) have an axial width (b4) of 5% to 15% of the width (b1) of the 0° belt layer (8). Commercial vehicle tires according to claim 1 or 2, characterized in that the rubber layer (12) extends continuously between the lateral sections (8b) of the 0° belt layer (8). Commercial vehicle tires according to claim 1 or 2, characterized in that two rubber layers (13) with an axial width (b3) of 10% to 20% of the width (b1) of the 0° belt layer (8) are present, wherein in the area between the rubber layers (13) the 0° belt layer (8) is located directly on the belt layer (6, 7) arranged radially within the 0° belt layer (8). Commercial vehicle tires according to one of claims 1 to 4, characterized in that the rubber layer(s) (12,13) ​​have a substantially constant thickness of 1 mm to 2 mm.

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