JP2002283809A - Tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve cut through resistance and belt end separation resistance which are suitable for a vehicle for running a rough road. SOLUTION: A main belt layer is composed of the widest belt layer with a width of 80% or less of tread width and the second widest belt layer adjacent to the belt layer. Reinforcing cords of the main belt layer are arranged so that they each cross an equator surface of a tire at an angle of inclination of 35 deg. or less, bundle 30% or more of the reinforcing cords of each layer so that each bundle contains not more than several reinforcing cords, and enlarge a space between the bundle and the adjacent bundle or the reinforcing cord. Furthermore, at least one protective layer reinforced by a high elongation cord is arranged outside the belt in a radial direction of the tire.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire excellent in cut-through resistance and belt-end separation resistance suitable for a vehicle on a rough road.

[0002]

2. Description of the Related Art In recent years, the load applied to tires, especially for heavy duty tires running on rough roads, tends to increase rapidly. Along with this, the deformation of the tire at the time of contact with the ground increases, and a crack occurs at the belt end, causing so-called belt end separation. The mechanism for generating the belt end separation is considered as follows. That is, the ends of the reinforcing cords embedded in parallel at predetermined equal intervals in the respective layers constituting the belt, and in the crossed belt, are arranged side by side in the circumferential direction toward the shoulder portion of the tire. Therefore, the rubber facing the cut end of the cord is crushed by the cut end of the cord every time the tire is deformed at the time of contact with the tire. As a result, in the initial stage, fine cracks gradually grow and are connected to each other, and furthermore,
It also extends and extends between the stacked layers, causing the belt end separation. Therefore, as described above, today, when the load applied to the tire is increased, the tire is greatly deformed at the time of contact with the ground, the belt end separation is likely to occur, and the durability of the tire is reduced.

[0003] As a countermeasure, several methods are conceivable. The first is to reduce the width of the belt or to reduce the deformation at the end of the reinforcing cord to avoid placing the cord end on the shoulder side where the deformation during ground contact is large.
This is a method of increasing the angle of the reinforcing cord with respect to the equatorial plane of the tire.However, in this case, the diameter growth of the tire is not sufficiently suppressed, and a cut separation failure in which the interface between the belt and the tread rubber separates is promoted. Method cannot be adopted. A second method is to increase the intervals between the cords by reducing the number of cords inserted so that the cracks generated at the cut ends of the cords are not easily connected to each other. However, in this case, the rigidity in the tire circumferential direction is reduced, and the cord density becomes coarse, so that the cut-through resistance to a scratch penetrating the tread is also deteriorated. As an improvement, it is conceivable to use a thick cord in order to maintain circumferential rigidity.However, new problems such as a thicker belt, lower heat build-up, and an increase in tire weight arise. Can not be adopted. The third is to bundle the cords arranged at a predetermined interval into several bundles to form a bundle cord, thereby maintaining the circumferential rigidity and widening the bundle cord interval, thereby making it difficult for cracks to be connected. Although this is a method of improving the separation resistance at the belt end, the problem of cut-through resistance, which is particularly important on a rough road, cannot be solved.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to suppress belt end separation without deteriorating cut-through resistance.

[0005]

In order to achieve the above object, the present invention has the following arrangement. (1) In a tire in which at least three layers of belts are arranged radially outward of a crown portion of a carcass extending between a pair of bead portions and extending in a toroidal shape, the belt has a tread width. A main belt layer comprising the widest belt layer of 80% or less and the second widest belt layer adjacent to the belt layer, the main belt layer having a reinforcing cord whose tire equatorial plane And the reinforcing cords in each layer of the main belt layer are arranged so as to intersect with each other at an inclination angle of 35 ° or less.
0% or more is made into a bundle of several or less bundles, and the space between this bundle and the bundle or reinforcing cord adjacent thereto (hereinafter, “cord spacing”)
), And at least one protective layer reinforced with a high elongation cord is disposed outside the belt in the tire radial direction. In the present invention, the “tread width” is defined as JATMA Year Book.
Refers to the width of the tread contact area when assembled to the standard rim of the applicable size specified in the above, adjusted to the air pressure for the maximum load capacity of the applicable size of the standard, and the maximum load of the applicable size of the standard is applied. (2) In the above (1), the protective layer has a treat strength of 5 to 40 of the treat strength of the widest belt layer.
% And an elongation at break of 4% or more. In the present invention, “treat strength” refers to strength at break. (3) In the above (2), the protective layer has a treat strength of 10 to 30% of the treat strength of the belt layer having the widest width,
In addition, the elongation at break is 5 to 8%. (4) In any one of the above (1) to (3), 30% or more of the reinforcing cords in all the belt layers are formed into a bundle of several or less bundles, and the interval between the bundle and the bundle or the reinforcing cord adjacent thereto. Is characterized by being enlarged. (5) In any one of the above (1) to (4), 30% or more of the reinforcing cords in the protective layer are made into a bundle of several wires or less, and the interval between this bundle and a bundle or reinforcing cord adjacent thereto is enlarged. It is characterized by having done. (6) In any one of the above (1) to (5), the width of the narrowest belt layer of the belt is 30% or more of the tread width. (7) In any one of the above (1) to (6), the width of the protective layer is 50 to 100% of the tread width.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail. FIG. 1 illustrates an approximate configuration of a tire according to the present invention. That is, a toroidal carcass 2 composed of a ply of organic fiber cords extending in the radial direction is formed as a skeleton between a pair of bead portions 1, and at least a radial outside of a crown portion of the carcass 2 and an inside of a tread 3 are provided. The belt 4 includes three (four: illustrated) belts 4 and at least one protective layer 5. Tire according to the present invention, in order to be able to be suitably used in vehicles for traveling on rough roads, for maintaining strength,
The belt requires at least three layers, each belt layer being arranged such that its reinforcing cords intersect each other between the belt stacks to form a crossed belt. Further, in order to suppress the tire diameter growth, it is preferable that the belt width is wide, but from the viewpoint of avoiding the arrangement at both ends in the tire width direction with a large amount of deformation, the belt width is the widest among the layers constituting the belt. The width BWmax of the belt layer is set to 80 of the tread width TW.
% Or less. The width BWmin of the narrowest belt layer among the layers constituting the belt is defined as the tread width T.
It is preferable to set W to 30% or more, but this is for the purpose of achieving both the suppression of the diameter growth and the separation property at the end. The inclination angle of the reinforcing cord of the widest belt layer is 35 ° or less with respect to the equatorial plane of the tire in order to secure circumferential rigidity. Further, the second widest belt layer relative to the widest belt layer is disposed adjacent to the widest belt layer, but the tread side and the anti-tread side of the widest belt layer. Either may be used. The angle of inclination of the reinforcing cord is 35 ° or less on the opposite side to the equatorial plane from the reinforcing cord of the widest belt layer. This is for suppressing the growth of the diameter (securing the rigidity in the circumferential direction). In addition, it is preferable that these inclination angles are 10 degrees or more. The reason for this is that if the angle is less than 10 °, the separation property at the end of the belt deteriorates, which causes a reduction in tire life. Examples of the material of these reinforcing cords include steel and organic fibers, and the cords include at least one filament and include those that are not twisted.

Further, in the present invention, the main belt layer of the belt is constituted by the widest belt layer and the second widest belt layer. At least one protective layer reinforced with cord
Arrange in layers. The cord that reinforces the protective layer is a high elongation cord, which differs from the cord used to reinforce the belt in physical properties, such as low elastic modulus and large elongation at break. In addition, examples of the material include steel and organic fibers. The reinforcing cord of the present invention is disclosed in JP-A-6-2629.
As described in Japanese Patent Application Publication No. 06-2006, not only the case where each bundle of codes divided into bundles consists of the same number of codes, but also the case where the number of codes differs depending on the divided bundles, The cords may be in contact with each other, and include a case where the cords are gathered at a smaller interval than the interval between adjacent cords. In addition, when cords that are not bundled are included in addition to cords divided into bundles, each bundle or a single cord is uniformly dispersed throughout the layer, which is a point of view of tire uniformity. preferable. When such a reinforcing cord contains cords divided into bundles, the rubberization method is to use a calendering roll with an improved comb-tooth-shaped roll, and disperse the cords at predetermined intervals. By embedding in a rubber sheet, it can be performed.

[0008] In the present invention, the reinforcing cord 3
0% or more cords are arranged in bundles, but when the cords are not included in the bundle (all cords are arranged at equal intervals). Cracks generated at the cord ends while maintaining relative rigidity in the circumferential direction This is because at least 30% of the codes are required to be bundled in order to obtain a code interval necessary to prevent the connection of the codes. FIG. 2A and FIG. 2B specifically illustrate a rubberized layer including a bundle of cords. (C) has the same number of hits as these, and the code is 1
The figure shows a case in which the books are individually dispersed at equal intervals D.
From the state of the (c), by the bundle of each three as (a), can wider cord spacing D _1, can be suppressed ties crack. Further, as shown in (b), be dispersed code not to the four bundles and bundle Similarly, wide cord spacing D _2, can suppress the growth of cracks. Furthermore, as the embodiment of the bundle, such as the bundle S ₁ shown in the left end of (a), in the case where each code in the bundle are in contact, as in the bundle S ₂ shown next to it, the bundle If the 3 Homma has small gap, as further bundle S ₃ shown next to it, to that in contact with the bundle, and may be selected if it contains some of the gaps, due to code contact bunch of S ₂ is preferred from the viewpoint of Furettengu prevention.

In order to be applied to a vehicle for traveling on rough roads, it is necessary to apply a rubberized layer containing such a bundle of cords to at least the main cross layer of the belt, but to apply it to all layers of the belt. Is more effective, and it is preferable to use it also for the protective layer. In the present invention, in order to prevent belt end separation, cords are divided into bundles in at least two wide layers, and the resulting reduction in cut-through resistance is reinforced with high elongation cords. This is prevented by further laminating a protective layer on the outer side in the tire radial direction. The mechanism is that, by the protective layer reinforced with high elongation cords, it gains elongation for the penetration of projections such as rocks, suppresses cord breakage, and densifies the mesh formed by cords , Preventing protrusions from penetrating. For this purpose, the treat strength of the protective layer is 5 to 40%, preferably 10 to 30% of the treat strength of the widest belt layer of the belt, and the protective layer has an elongation at break of 4% or more. , Preferably 5-8
% Is preferable. Further, the reinforcing cords of the protective layer are also preferably bundled, for the same reason as in the case of the above-described reinforcing cords of the belt. Also, the width P of the protective layer
W (see FIG. 1) is preferably 50 to 100% of the tread width, but if it is less than 50%, it is too narrow to obtain the effect of providing the protective layer. Here, the width of the widest belt layer is restricted to 80% or less of the tread width, while the width of the protective layer is allowed to be 100% of the tread width because of the rocks or the like on the main belt layer. This is in order to prevent the penetration. Further, even if a crack occurs at the belt end of the protective layer, the crack here is less likely to cause a burst or the like.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below. FIGS. 3 and 4 show tires each specifically showing a crown portion.
It was produced in Example 1 and Example 2 described below, and the effect of the present invention was demonstrated.

Example 1 (see FIG. 3) The tire used was ORR 18.00R25, an appropriate rim 13.00, a load load 106820N, and an internal pressure 700 kp.
a, Experiments were performed under the conditions of a speed of 15 km / h. Tread width: 425mm Belt: 4 layers (first layer 4a, second layer in order from the carcass side)
The layer 4b, the third layer 4c, the fourth layer 4d), and the second layer 4b are the widest layers, and the reinforcing cords of only the invention examples were all divided into bundles. Further, the third layer 4c is the second widest layer, and similarly, only the reinforcing cords of the present invention are all formed of a bundle. These second
The main belt layer is composed of the layer 4b and the third layer 4c. In the bundle, the adjacent cords in the bundle were in close contact with each other. The first layer 4a and the narrowest fourth layer 4d do not divide the cord into bundles. Protective layer: Only one layer (fifth layer 5), and cords are not bundled.

First layer: width 280 mm, cord inclination angle right 20 ° Second layer: width 320 mm, cord inclination angle left (variable) ° Third layer: width 300 mm, cord inclination angle right (variable) ° 4 layers: width 150 mm, cord inclination angle 20 ° to the left Protective layer: width 330 mm, cord inclination angle 25 ° to the left (the above “variables” were variously changed as shown in Table 1.) Reinforcement cords for each layer of the belt: Material steel, structure 1 + 6,
Driving density 24.21 strands / 50mm, cord spacing when divided into bundles 3.00mm, cord spacing between cords not divided into bundles 0.82mm Reinforcing cord of protective layer: material steel, structure 3 × 4, implantation density 48 / 50mm, cord spacing 0.48mm

Evaluation method Treat strength: The strength of the cord was evaluated by multiplying the strength of the cord by the number of strikes using an Instron tensile tester. Elongation at break: Elongation (%) at cord cutting was measured and evaluated in the same manner as above. The tensile tester was used to measure the soldered sample under the conditions of a capacity of 500 kg or more, a pulling speed of 20 ± 2 mm / min, and a length of the soldered sample of 200 ± 1 mm. The fixation was performed. Cut-through resistance: The running distance until the tire breaks the cord on the protruding drum was measured, and the index was set as an index with the conventional example being 100. The larger the value, the better. Cut separation resistance: 120 on test drum
The interlayer crack width of the belt after running for an hour was measured, and was indexed with the conventional example as 100. The smaller the value, the better. Belt end separation resistance: The belt end separation length after running on the test drum for 250 hours was measured, and the result was indexed with the conventional example as 100. The smaller the value, the better.

[0014]

[Table 1]

Example 2 (see FIG. 4) The tires used were ORR40.00R57, an appropriate rim of 29.00, a load of 999600N, and an internal pressure of 700 kp.
a, Experiments were performed under the conditions of a speed of 10 km / h. Tread width: 980 mm Belt: 4 layers (first layer 4e, second layer in order from the carcass side)
Layer 4f, third layer 4g, fourth layer 4h) and second layer 4f are the widest layers, and third layer 4g is the second widest layer. The second layer 4f and the third layer 4g constitute a main belt layer. The first layer 4e is the narrowest layer.
In the layer where the bundle was adopted, everything was divided into bundles. Protective layer: 2 layers (fifth layer 5a, sixth layer
In layer 5b), all the cords were divided into bundles in the layer which also employed bundles. In the bundle, adjacent cords are configured to be close to each other.

First layer: width 320 mm, cord inclination angle 5 ° to the right Second layer: width 700 mm, cord inclination angle to the left (variable) ° Third layer: width 650 mm, cord inclination angle to the right (variable) ° Fourth layer: width 400 mm, cord inclination angle 10 ° to the left Fifth layer: width 820 mm, cord inclination angle 27 ° to the left Sixth layer: width 640 mm, cord inclination angle 23 ° to the right (The above “variable” is shown in Table 2) Various changes were made as shown.) Reinforcement cord for each layer of belt: Material steel, structure 7 × (3
+9) +1, driving density 7.00 strands / 50 mm, cord spacing 4.02 mm when divided into bundles, cord spacing 2.51 mm between cords not divided into bundles Reinforcement cords for protective layer: material steel, structure 4 × 6 The driving density was 14.5 lines / 50 mm, the cord spacing when divided into bundles was 4.84 mm, and the cord spacing when not divided into bundles was 0.4 mm. The evaluation method was the same as described above.

[0017]

[Table 2]

[0018]

According to the present invention, a tire excellent in cut-through resistance and belt-end separation resistance suitable for a vehicle traveling on a rough road can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view of a tire.

FIG. 2 is a cross-sectional view of a rubberized layer showing a dispersion state of a reinforcing cord.

FIG. 3 is a sectional view of a crown portion of the tire used in Example 1.

FIG. 4 is a sectional view of a crown portion of a tire used in Example 2.

[Explanation of symbols]

 2 Carcass 3 Tread 4 Belt 5 Protective layer

Claims (7)

[Claims] 1. A tire having a carcass crown portion extending in a toroidal shape extending between a pair of bead portions in a tire radially outward direction.
In a tire having a belt comprising at least three layers, the belt comprises a widest belt layer having a width of not more than 80% of a tread width, and a belt layer adjacent to the second widest belt layer. From the main belt layer,
The main belt layers are arranged such that the reinforcing cords thereof intersect with the tire equatorial plane at an inclination angle of 35 ° or less, respectively, and the reinforcing cords in each of the main belt layers have 30% or more of the reinforcing cords in several layers. The bundle and the spacing between the bundle and the adjacent bundle or reinforcing cord are enlarged, and further, at least one protective layer reinforced with a high elongation cord is arranged on the outer side of the belt in the tire radial direction. A tire characterized by becoming. 2. The tire according to claim 1, wherein the protective layer has a treat strength of 5 to 40% of a treat strength of the widest belt layer and an elongation at break of 4% or more. 3. The tire according to claim 2, wherein the protective layer has a treat strength of 10 to 30% of the treat strength of the widest belt layer and an elongation at break of 5 to 8%. 4. The method according to claim 1, wherein 30% or more of the reinforcing cords in all the belt layers are formed into a bundle of several or less bundles, and the interval between the bundle and the bundle or the reinforcing cord adjacent thereto is enlarged. The tire according to any one of claims 1 to 3. 5. The method according to claim 1, wherein 30% or more of the reinforcing cords in the protective layer are bundled within several wires, and the interval between the bundle and the adjacent bundle or reinforcing cord is enlarged. The tire according to any one of the above. 6. The width of the narrowest belt layer of the belt,
The tire according to any one of claims 1 to 5, wherein the tire width is 30% or more of a tread width. 7. The protective layer has a width of 50 to 10 of a tread width.
The tire according to any one of claims 1 to 6, which is 0%.