JPH04237607A - Tire for high-speed heavy load - Google Patents

Abstract

PURPOSE:To suppress separation between plies in a high-speed heavy-load tire for an aircraft or the like by forming a reinforcing layer of a strip sheet of the specified thickness and width so as to cover the broken end of a carcass or the tread reinforcing ply into U-shape, and specifying the distance between cords. CONSTITUTION:Rubber projecting layers 20A, 20B for covering the respective end parts of the outer ply 14a1 and inner ply 14a2 of a rubber reinforcing layer 20 are covered into U-shape with a strip rubber sheet 16 to perform vulcanization molding. This strip rubber sheet 16 is formed into semi-vulcanized or unvulcanized strip shape of 0.2mm or more and 2.0mm or less in thickness and 20mm or more and 30mm or less in width, and attached in the state of covering the broken end (e) of each ply 14a into U-shape. The distance l between the respective cords 27 of the outer ply 14a1 and inner ply 14a2, the distance l2 between the respective cords 27, 26 of the outer ply 14a1 and a belt ply 10a1, and the distance l3 between the respective cords 27, 25 of the inner ply 14a2 and a carcass ply 7b1 are set 1/4 or more and 2.0 or less as long as the diameter of the cord 27.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed, heavy-load tire that can effectively suppress inter-ply peeling that progresses from the discontinuous ends of the carcass and tread reinforcing layer and improve the structural durability of the tire.

0002

[Prior art and problems to be solved by the invention] In recent years,
Tires used under high load and high speed conditions, such as aircraft tires, have a radial structure in which the outside of the carcass is tightened with a strong reinforcing layer in the radial direction to improve running stability, wear resistance, fuel efficiency, etc. Things are being adopted.

However, in such radial tires, the tread rigidity is greatly increased by the reinforcing layer, and the amount of deformation is reduced. Deformation increases significantly. As a result, shearing force acts in a concentrated manner at the discontinuous ends of both ends of the reinforcing layer that discontinue at the shoulder portion, and at the discontinuous end of the upper end of the carcass folded portion that discontinues at the bead portion, which induces delamination between the plies starting from each discontinuous end. It is known that structural durability can be impaired.

[0004] In order to suppress such ply separation, conventional methods have been to change the cord angle and cord material of the reinforcing layer at the shoulder section, or to add a new bead reinforcing layer at the bead section. Measures have been taken to increase the rigidity and reduce the amount of deformation, but these efforts have not resulted in a sufficiently satisfactory effect.

[0005] Therefore, the present inventors set the distance between the cords between adjacent plies at the broken end to be 1/4 or more and 2.0 times or less of the cord diameter, and the rubber material interposed between the cords is The idea was to alleviate the shearing force by expanding and contracting the material.

However, since this discontinuous end causes a difference in rigidity between the outside and the outside, the external pressure during green tire formation and the internal filling pressure during inflation during vulcanization molding act unevenly, causing the rubber interposed between the cords to Let the material flow outside,
It has been found that the distance between cords at the discontinuous end can be locally reduced. In order to secure the distance between the cords after spillage, it may be proposed to increase the overall coating thickness of the topping in each ply, but this would greatly increase the tire weight and impair fuel efficiency and heat generation. At the same time, for example, in the case of a tread reinforcing layer, the in-plane rigidity of the tread is reduced and running stability is deteriorated.

[0007] The present invention is based on the provision of a rubber protective layer that covers the broken ends using a strip rubber sheet of a predetermined size and is folded back on both sides of the ply, thereby reducing the distance between the cords at the broken ends without causing the above-mentioned disadvantages. The purpose of the present invention is to provide a high-speed, heavy-load tire that can ensure high-speed, heavy-duty tires, suppress inter-ply peeling, and improve tire durability.

[0008]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the high speed heavy load tire of the present invention has cords which are folded from the tread section through the sidewalls at the bead core of the bead section and aligned parallel to each other at the upper end of the folded section. A carcass consisting of a plurality of carcass plies that are discontinued at 1 and 2, and a carcass that is arranged radially outside of this carcass and inside the tread part and that goes around the tire and aligns the cords parallel to each other and that the cords are aligned in the circumferential direction of the tire. A reinforcing layer consisting of a plurality of plies in which the cord is interrupted on both sides in the axial direction of the tire by tilting, and has a length of 0.2 mm or more and 2.0 m.
A rubber protective layer is provided by folding a strip rubber sheet with a thickness of not more than 20 mm and a width of not less than 20 mm and not more than 300 mm on both sides of the ply, covering the broken ends, and in each of the plies for the carcass or the reinforcing layer. The distance between the cord of the ply and the cord of the ply adjacent to the ply in the thickness direction of the ply is at least 1/4 times the diameter D1 or D2 of the cord of the carcass or reinforcing layer ply, and 2.
It is set to be 0 times or less.

[0009]

[Operation] A strip rubber sheet of a predetermined size is folded in a U shape and pasted on the ends of the ply for the carcass and reinforcing layer.
A protective rubber layer is formed over the broken ends of the ply. Therefore, even if a certain amount of rubber material between the cords flows out during internal pressure filling during vulcanization molding, the required distance between the cords at the broken end is ensured, and the shearing force during tire deformation is alleviated and absorbed, and the gap between the plies is Can prevent peeling. In addition, since this rubber protective layer is locally provided only at the end of the ply, it is possible to maintain running stability, fuel efficiency, etc. without causing a decrease in in-plane rigidity of the tread or an increase in tire weight.

0010

[Example] Hereinafter, an example of the present invention will be described in which the tire size is 4.
An example of a 6×17R20 aircraft tire will be explained based on the drawings.

In FIG. 1 showing a cross section of a tire mounted on a regular rim R and in a normal internal pressure state with normal internal pressure applied, a high-speed heavy load tire 1 (hereinafter referred to as tire 1) has a bead portion 3 through which a bead core 2 passes; The tire includes a sidewall part 4 connected to the bead part 3 and extending outward in the tire radial direction, and a tread part 5 connecting the outer ends of the sidewall part 4.

Furthermore, the tire 1 includes an inner layer 7A consisting of a plurality of layers, for example, four plies 7a, . . . , which fold the bead core 2 from the inside to the outside of the tire. Multiple sheets unrolled from the outside to the inside,
For example, a carcass 7 is provided which has an outer layer 7B consisting of two outer plies 7b, 7b.

The inner ply 7a has sidewall portions 4,
A folded part 7 in which the bead core 2 is folded from the inside of the tire to the outside at both ends of the main body part 70 which passes through the tread part 5 and forms a toroidal shape.
1, and the outer ply 7b has a toroidal body part 73.
The bead core 2 is provided with an unrolling part 74 unrolled outside the bead core 2.

The inner and outer plies 7a and 7b each have a sheet shape in which a cord arrangement body in which cords 25 are arranged at an angle of 75 degrees to 90 degrees with respect to the tire equator is covered with a topping rubber 30. Each cord 25 of the outer ply 7a is interrupted at the upper end of the folded portion 71, and each cord 25 of the outer ply 7b is interrupted at the inner end of the unwound portion 74. Further, in this example, the carcass 7 is stacked in different directions between adjacent carcass plies so that the cords 25 are inclined to alternately intersect with the circumferential direction.

[0015] As the cord 25 of the carcass, an organic fiber cord such as rayon, polyester, vinylon, nylon, aromatic polyamide, etc. is used.

A bead apex 9 made of tapered rubber extending in the radial direction of the tire is provided above the bead core 2 to increase rigidity and to disperse stress caused by bending of the folded portion 71 of the carcass 7. Further, a chafe (not shown) for preventing rim displacement may be provided on the outer surface of the bead portion 3.

Furthermore, in this example, the tread portion 5 includes a belt in which a reinforcing cord 26 is located at the outside in the radial direction of the carcass 7 and arranged at a cord angle of 5 degrees or less with respect to the tire equator CO. 10, and a reinforcing cord 2 interposed between the belt 10 and the carcass 7 and inclined at a cord angle of 0 or more and 70 degrees or less with respect to the tire equator CO.
A reinforcing layer 15 consisting of a cut breaker 14 having a cut breaker 7 is wound in the tire circumferential direction.

The belt 10 has a plurality of pieces, for example 6 to 10 pieces, each of which has the cord 26 embedded in the topping rubber 30.
It is formed from two plies 10a, and each cord 26 is interrupted at both ends of the ply in the tire axial direction. Also, the ply 10
a... is gradually narrowed outward in the radial direction, so that the belt 10 has a substantially trapezoidal cross section including the tire shaft, and its side surface 10S has substantially the same thickness as the outer surface SB of the tire buttress portion. It becomes a slope along the slope. Further, the maximum width WB of the belt 10 in the tire axial direction, in this example, the width of the innermost wide ply 10a1, is set in a range of about 75 to 85% of the total tire width WT. Note that the code 26 is for each ply 10
Alternately tilt in the opposite direction. Note that the ply width is measured as the distance between the outermost cord ends of the ply.

The cut breaker 14 is made of, for example, two plies 14a1 and 14a2 (the plies 14a1 and 14a2 are collectively called 14a), each cord 2
7 is interrupted at the ply end, and in this example, the width W1 in the tire axial direction of the outer ply 14a1 is smaller than the width W2 of the inner ply 14a2 adjacent to the ply 14a1 on the inside, and the ply 10a1 of the belt 10 adjacent on the outside Width W3
That is, in this example, the stress is distributed by setting the width to be smaller than the maximum width WB and by changing the position of each ply end. Note that the width W1 may be set to be the same as or wider than the widths W2 and W3.

This cut breaker 14 is connected to the tread portion 5.
The purpose is to increase the in-plane bending stiffness and cornering force, and for this purpose, the cords 25 of the carcass and the cords 26 of the belt are arranged in a triangular structure. Therefore, since the cord 25 of the carcass is tilted at an angle of 75 to 90 degrees with respect to the tire equator, and the cord 26 of the belt is tilted at an angle of 5 degrees or less, the cord 27 of the cut breaker is preferably tilted at an angle of 10 to 45 degrees with respect to the tire equator CO. , more preferably at an angle of 10 to 30 degrees to form a strong triangular structure. In addition, the code 25 of the carcass is 75-8
When the angle is 0 degrees, the inclination of the cord 27 of the cut breaker with respect to the tire equator can also be set close to 0 degrees.

In this way, by adding the cut breaker 14 itself, the cords 25 and 26 are
The triangular structure increases in-plane bending stiffness, increases cornering force, and suppresses the formation of standing webs.

[0022] In the present invention, such a belt 10
In order to prevent ply peeling at the reinforcing layer 15 and the folded portion 71 of the carcass due to bending deformation from the shoulder portion 5A to the bead portion 3, which increases due to the formation of the reinforcing layer 15 consisting of the reinforcing layer 15 and the cut breaker 14, the reinforcing layer 15 is Rubber reinforcing layers 20 and 21 are provided at both ends of the layer 15 and at the upper end of the folded portion, respectively.

In this embodiment, the cord 27 of the cut breaker 14 is the cord 25 of the carcass and the cord 2 of the belt.
The stretching direction is different, such as intersecting belt 6, and belt 1
In addition to the difference in rigidity between the cut breaker 14 and the carcass 7, separation is likely to occur particularly between the plies of the cut breaker 14 and between the plies of the carcass and the belt adjacent to the plies of the cut breaker 14 in the shoulder portion 5A. Therefore, in this example, the rubber reinforcing layer 20 is arranged at both ends of the cut breaker 14 in the reinforcing layer 15.

That is, the rubber reinforcing layer 20 includes a rubber protective layer 20A that covers the end of the outer ply 14a1, and a rubber protective layer that covers the end of the inner ply 14a2, as shown in an enlarged view in FIG. 20B. Also, each rubber protective layer 2
0A and 20B are semi-vulcanized or unvulcanized strips having a thickness t of 0.2 mm or more and 2.0 mm or less and a width W of 20 mm or more and 300 mm or less, as shown in FIG. 3, respectively. Rubber sheet 16 is attached to each ply 14 in advance.
The ply 14a is folded in a U-shape on both sides of the upper and lower surfaces in the tire radial direction, covering the broken end e which is the end surface of the ply 14a, and is then used to form a green tire and placed in a mold. Formed by vulcanization. Note that this strip rubber sheet 16 flows out to some extent from the discontinuous end e due to the external force of sequentially laminating the belt 10, tread rubber, etc. during the formation of a green tire, and the filling internal pressure during vulcanization. However, since it has the thickness t in advance, the distance l1 in the ply thickness direction between the cord 27 of the outer ply 14a1 and the cord of the inner ply 14a2, and the distance l1 between the cord 27 of the outer ply 14a1 and the cord of the inner ply 14a2 and the belt 1
The distance l2 between the cord 26 of the inner ply 10a1 and the distance l3 between the cord 27 of the inner ply 14a2 and the cord 25 of the ply 7b1 of the carcass 7 are respectively determined by the cord 2.
It can be maintained within a range of 1/4 or more and 2.0 times or less of the diameter D2 of No. 7, and the shearing force that acts between the plies and concentrates at the discontinuous end e can be relaxed and absorbed by its rubber elasticity.

[0025] Therefore, the rubber protective layers 20A and 20B need to expand and contract following the cords that sandwich them, and for this purpose, the 100% modulus must be 40 or more and 70 kg/
cm2 or less, elongation at break of 200 or more and 350%
or less, and the stress at break is 150 or more and 300 kg.
/cm2 or less is used.

[0026] Furthermore, the 100% modulus is 40 kg/cm
If it is less than 2, heat generation will be large and thermal damage will easily occur, and if it exceeds 70 kg/cm2, the effect of relieving shearing force will be insufficient, and the adhesiveness with the cord will decrease, making it easy to cause cord looseness.

[0027] If the elongation at break is less than 200%, the followability to the cord is insufficient and rubber breakage is likely to occur;
If the temperature exceeds , the heat generation will increase. Furthermore, the stress at break is 1
If the weight is less than 50kg/cm2, the strength will be insufficient and the weight will exceed 300kg.
If it exceeds g/cm2, the shear force relaxation effect tends to be poor.

Similarly, the inter-cord distances l1, l2, l3
If it is less than 1/4 of the diameter D2, no shearing force relaxation effect can be expected, and if it exceeds twice the diameter D2, heat generation will increase.

The thickness t of the strip rubber sheet 16 for forming the rubber protective layer 20 is a value that takes into consideration the amount of rubber flowing out during tire formation, and when it is smaller than 0.2 mm and larger than 2.0 mm, Inter-cord distance within range l1, l2, l3
becomes difficult to maintain. Also, if the width W of the strip rubber sheet 16 is less than 20 mm, the stress relaxation effect will not be sufficiently exhibited, and if it exceeds 300 mm, the weight of the tire will increase, and
This reduces tread rigidity and impairs running performance.

The rubber protective layer 21 disposed on the folded portion 71 of the carcass 7 is similarly made of a strip rubber sheet 16 covering the broken end e of each inner ply 7a in a U-shape, as shown in FIG. Rubber protective layers 21A to 21 formed
D, thereby setting the distances L1 to L5 between the cords between the plies at the discontinuous end e to 1/4 or more and 2.0 times or less, respectively, of the diameter D1 of the cord 25 of the carcass.

In the present invention, the reinforcing layer 15 may be formed only by the belt 10, and in such a case, a rubber protective layer is formed at both ends of the ply 10a. Further, when the rubber protective layer 21 is provided only on the folded portion 71 of the carcass 7, the durability of the bead portion can be improved.

[Specific Example] A tire having the tire structure shown in FIG. 1 and a tire size of 46×17R20 was manufactured based on the specifications shown in Table 1, and the durability of the shoulder and bead portions of the trial tire was measured.

[0032]

[Table 1]

Table 2 shows the rubber composition and rubber physical properties of the rubber protective layer shown in Table 1.

[0034]

[Table 2]

As a high-speed durability test, a take-off test based on the US Civil Aviation Bureau standard TSO-C62c was conducted 100 times under a 150% standard load to evaluate the presence or absence of carcass rubber failure. The bead heat generation index is the value obtained by subtracting the bead temperature before each run from the average bead heat generation temperature after 100 runs, and dividing the temperature difference by the bead temperature before the run.

As a low-speed durability test, the vehicle was continuously driven for up to 3,000 km at a speed of 11 km/H under a 120% standard load, and evaluated based on the travel distance that resulted in shoulder and bead damage.

[0037]

[Effects of the Invention] As described above, the tire of the present invention is provided with a rubber reinforcing layer that covers each broken end of the carcass ply or the reinforcing layer ply by folding it in a U-shape using a strip rubber sheet of a predetermined size. Therefore, the shearing force concentrated at the discontinuous end can be alleviated without causing an increase in tire weight, a decrease in running performance, etc., and separation between the plies can be suppressed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a partially sectional view showing an enlarged shoulder portion.

FIG. 3 is a sectional view showing a strip rubber sheet.

FIG. 4 is a cross-sectional view showing an enlarged bead portion.

FIG. 5 is a cross-sectional view illustrating the distance between the cords.

[Explanation of symbols]

2 Bead core 3 Bead part 4 Sidewall part 5 Tread section 7 Carcass 7a　Ply for carcass 10a, 14a　Ply for reinforcing layer 15 Reinforcement layer 16 Strip rubber sheet 20, 21 Rubber protective layer 25, 26, 27 code 71 Turning part e Interrupted end

Claims (1)

[Claims] Claim 1: A carcass consisting of a plurality of carcass plies, in which cords are folded from the tread part through the sidewalls at the bead core of the bead part and aligned parallel to each other and are interrupted at the upper end of the folded part, and a radially outer side of the carcass. and a reinforcing layer consisting of a plurality of plies disposed inside the tread portion, which goes around the tire, aligns the cords parallel to each other, and whose cords are discontinued on both sides in the tire axial direction when the cords are tilted with respect to the tire circumferential direction. and a thickness of 0.2 mm or more and 2.0 mm or less and 20
A rubber protective layer is provided by folding a strip rubber sheet having a width of 1 mm or more and 300 mm or less on both sides of the ply to cover the broken end, and in each ply for the carcass or reinforcing layer, a rubber protective layer is provided between the cord of the ply and the ply. The distance between the cords of adjacent plies in the thickness direction of the ply is defined as the diameter D1 of the cord of the ply for the carcass or reinforcing layer.
Or a high-speed, heavy-load tire that is 1/4 times or more and 2.0 times or less of D2.