JPH06262906A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To prevent the growth and progress of a crack in a reinforcing element terminal so as to improve tire durability by dividing the given percentage of reinforcing elements arranged in a rubber coated layer into bundles within a given number, and making the distribution intervals of the reinforcing elements adjoining the bundles a given interval. CONSTITUTION:At least 30% of reinforcing elements are divided into bundles 4 within several pieces, in the arrangement of reinforcing elements 3 composed of the monofilament of an organic fiber code or an organic fiber, in a rubber coated layer as a tread reinforcing belt for a tire. Dispersion intervals delta to the reinforcing elements 3 adjoining to the bundles 4 are made broader than intervals S at the time of equal interval alignment. Consequently, the growth and progress of a crack in the terminal vicinity of the reinforcing element 3, which is the cause of separation at an end part, can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a skeleton of a tire and a constituent material for reinforcing the tire, such as a belt for controlling tread or a folded portion of a carcass ply for reinforcing bead and a reinforcing layer for bead. The present invention relates to a pneumatic tire whose durability is improved by improving

As is well known, among the tire constituent materials, first, the belt controls the tread, and particularly in the case of the radial tire, plays a role of increasing the rigidity in the circumferential direction, and the carcass forms the skeleton of the tire, and The folded portion also contributes to the reinforcement of the bead portion, and the bead portion reinforcement layer contributes to the reinforcement of the bead portion by suppressing the collapse of the bead portion toward the rim flange side that occurs when the tire touches the ground. The bead portion reinforcing layer is usually arranged so as to extend from the vicinity of the bead core or inside the tire of the bead core toward the tire radial direction outer side along the folded portion of the carcass ply to a position beyond the folded end.

[0003]

2. Description of the Related Art The belt of a tire has a reinforcing element formed of cords arranged in parallel in parallel to the equatorial plane of the tire, and the carcass ply is oblique or perpendicular to the equatorial plane of the tire at the crown portion of the tire. Reinforcing elements made of steel cords, monofilaments, organic fiber cords or monofilaments that are arranged in parallel with each other, and similarly, the bead reinforcing layer is made of steel cords and organic fiber cords that are obliquely arranged in parallel with respect to the carcass cords. It is customary to use as a rubberized layer embedded at equal intervals.

[0004]

In the conventional component in which the parallel arrangement of the reinforcing elements has been arranged at equal intervals, the reinforcing elements of each reinforcing element are arranged at the ends thereof, that is, at the width ends of the belt. Since the rubber facing the terminal is picked up each time the tire touches the ground, a small crack is generated at first, and then it grows over the adjacent reinforcing elements, and then it is also connected between the laminated layers of the belt and suddenly grows. Expanded to the so-called belt separation. This crack propagation rate is remarkably fast, and this particularly determines the durability of the radial tire.

Further, in the carcass, at the end of the folded-back portion, the rubber facing the end of each reinforcing element is picked up every time the tire is grounded and deformed, so that a fine crack is generated first, and then the reinforcing elements are adjacent to each other. It grows over a period of time, then progresses toward the sidewalls and stiffeners and expands rapidly, which is one of the factors that determine the durability of the tire beads.

Similarly, in the bead reinforcing layer, if the end of the reinforcing element on the outer side in the tire axial direction or the bead reinforcing layer extends further from the vicinity of the bead core toward the inside of the tire, At the end in the tire axial direction, the rubber facing the end of each reinforcing element is caught at each contact deformation of the tire, so that a minute crack is generated at first, and eventually the reinforcing element grows across adjacent ones. After that, the adjacent bead portion reinforcing layers are connected to each other, or further extend toward the outer side of the carcass ply or the tire and rapidly expand, which also becomes a factor that determines the durability of the tire bead portion.

[0007] It is important to suppress the growth of the above-mentioned cracks. For that purpose, it is of course advantageous that the distance between the adjacent reinforcing elements is wide, but on the other hand, it is necessary in addition to the strong demand for reducing the weight of the tire. Code simplification
It is desirable to reduce the wire diameter of the reinforcing element. as a result,
In order to maintain the same tire strength, it is obvious that the reinforcement elements should be driven in many times, and the spacing between the reinforcement elements is rather narrow, which is incompatible with crack growth suppression.

Therefore, it is effective and appropriate for the deterioration of tire durability due to the subsequent growth and development of fine cracks generated in the rubber at the width end of the tire constituent member facing the end of the reinforcing element. It is an object of the invention to provide a solution, which is a problem imposed on this type of reinforcement, and to provide a pneumatic tire with improved components that can be advantageously adapted to this problem. is there.

[0009]

The above-mentioned object is properly achieved by the constitution summarized below. In a pneumatic tire having a rubberized layer composed of a predetermined number of reinforcing elements arranged in parallel with each other as a constituent material, at least 30% of the reinforcing elements arranged in the rubberized layer are divided into a bundle of several or less. ,
A pneumatic tire characterized in that a dispersion interval between the bundle and the reinforcing elements adjacent thereto is made wider than in the case where the predetermined number of the reinforcing elements are arranged at equal intervals in the rubberized layer.

The above-mentioned constituent materials include a belt used for reinforcing the tread of a tire, at least one layer of a carcass ply wound from the inside to the outside of a tire around a pair of bead cores, or a pair of bead cores of a tire around a pair of bead cores. A particularly advantageous fit is at least one bead reinforcement layer extending along the folds of the carcass ply which folds from the inside to the outside. In addition to these, there are constituent members such as a belt reinforcing layer that covers a part or the entire width of the belt, and it goes without saying that these are also included in the constituent members. Here, as the reinforcing element, cords or monofilaments of organic fibers are preferably used for the belt and the bead reinforcing layer, and cords or monofilaments of organic fibers or steel are preferably used for the carcass ply.

Further, the bundle includes the same number of reinforcing elements, the bundle includes different numbers of reinforcing elements, and at least some of the adjacent reinforcing elements in the bundle are arranged in contact with each other. Each case is included in which the gaps between the adjacent reinforcing elements in the bundle are arranged to be narrower than the distribution gap of the bundle.

It should be noted that since a surplus on the section of the bundle may occur depending on the total number of the reinforcing elements required for forming the skeleton of the tire by the constituent materials and reinforcement, regarding the reinforcing element protruding from the section of the bundle. Can be arranged in a distributed manner so as to be approximately balanced over the entire circumference of the tire.

In the present invention, in order to prepare the rubberized layer of the reinforcing element to be used as the constituent material, the treat material is first prepared by the calendering roll which is an improved comb tooth-shaped roll. This comb-tooth roll is thereby provided with a side-by-side arrangement of several reinforcing elements, for example, in sections of a bundle addressed to two,
Uses a calendar roll to help the rubber sheet be united.

The comb tooth roll has a plurality of circumferential grooves for the above-mentioned juxtaposed arrangement of reinforcing elements, the circumferential grooves being defined by collar-shaped comb teeth for guiding between adjacent ones of the sorting bundles. The groove has a groove width corresponding to a piece bundle of two individual reinforcing elements which are in unconstrained contact with each other. When the treat material thus produced is used for reinforcement of a tire or the like, when the reinforcing element is inclined with respect to the equatorial plane of the tire, the treat width is diagonally cut according to the required inclination, and then, A rubber strip in which the ears at the width ends of the treat are rejoined is wound around a raw fabric coil together with the liner, and is used in the tire building process.

[0015]

As described above, the process of rubber breakage at the end of the component is accompanied by fine cracks in the rubber facing the end of the reinforcing element every time the tire is repeatedly deformed. Aside from the initial stage where it travels along the surface of the stiffening element, if the stiffening elements are arranged in parallel at equal intervals according to the conventional technique, they will quickly start to grow across the adjacent stiffening elements. Then, there is a disadvantage that they are connected between the laminated layers of the constituent materials or expand rapidly toward the outside or the inside of the tire with the constituent materials as the center, and progress into various separations and cracks.

On the other hand, according to the present invention, when the bundles and the bundles or the reinforcing elements that do not belong to the bundles are mixed, the dispersion distance between the reinforcing elements and the bundles is much wider than in the case of the equidistant arrangement. Therefore, the crack growth after the initial stage is delayed between the reinforcing elements adjacent to each other with the dispersion interval according to the dispersion interval, so that the subsequent separation and the rapid expansion of the crack are effectively suppressed. When the rigidity of the reinforcing element is high, minute cracks are likely to occur early due to the above-mentioned pecking of the reinforcing element end. Therefore, in the reinforcing element having particularly high rigidity, for example, steel cord or organic fiber, aromatic polyamide (Kevlar) is used. 2) is used, the effect of suppressing expansion of interlayer separation by the constituent material of the present invention becomes particularly large.

Here, even if only a part of the total number of the reinforcing elements between the rubberized layers is bundled and the distributed arrangement is such that the reinforcing elements are almost evenly distributed over the entire circumference of the tire, the bundle and Since the distance between the adjacent reinforcing elements is wider than the distance between the reinforcing elements in the case of the regular interval arrangement according to the conventional technique, the rapid expansion of separation and cracks is suppressed. However, since the effect may not be significant, at least 30% of the total circumference of the reinforcing element should be targeted in terms of the section of the bundle. By doing so, the effect becomes remarkable.

Here, the number of the reinforcing elements in the bundle is set to several or less, which is advantageous because the dispersion interval can be made wider as the number of the reinforcing elements is increased. Therefore, it is necessary to make a bundle of several bundles, preferably 2 to 9 bundles, because of the disadvantage of crack development occurring in the bundle.

[0019]

【Example】

Example 1 As a tread reinforcing belt 2 of a radial tire 1 for a passenger car having a size of 185/70 R14 whose cross section is shown in FIG. 2 to 7 in comparison with various arrangements of reinforcing elements when used in a belt,
The cross-section orthogonal to the axial direction of the reinforcing element at a position separated by several mm from the width end of the tread reinforcing belt 2 is illustrated, 3 is a reinforcing element made of an organic fiber cord or an organic fiber monofilament, and 4 is a bundle thereof.

The tread reinforcing belt 2 is the conventional example shown in each upper stage (a) of FIGS. 2 to 7, and the organic fibers in the rubberized layer are arranged at equal intervals s. As shown in each lower row (b) for different cases of this invention,
The division bundles 4 for every several reinforcing elements 3 are arranged at a spacing δ wider than the regular spacing s. In the example of FIG. 3 (b), the bundles 4 and 4'show the case where the number of the reinforcing elements 3 is alternately different.

Each of the test tires 1 shown in Table 1 below, which were made by trial using the reinforcing elements having different cord types according to the above-mentioned conditions, was subjected to a drum tester under the conditions of an internal pressure of 1.9 kgf / cm ² and a load of 455 kg. After running for 60,000 km at a running speed of 80 km / h, it was dissected and the crack length near the width end of the belt 2 was measured. The results are shown in Table 1. Also, in contrast to the conventional example shown in each upper row (a) of FIGS. 6 to 7, an example in which less than half of the entire circumference is divided into a bundle is shown in FIG. 6 (b). An example of the divided case is shown in Fig. 7 (b). # 5 in Table 1,
# 6 shows the results in these cases.

[0022]

[Table 1]

In this example, the belt 2 is formed by laminating two sheets,
The reinforcing elements of each layer intersect each other at 24 ° with respect to the equatorial plane of the tire, and the layer on the tread side is slightly narrower than the layer on the carcass side.

The above-mentioned cracks generated near the width end of the belt are
It occurs only in the layer on the tread side, and therefore the measurement results are for only the layer on the tread side. Based on this fact, it is of course possible to apply the rubberized layer of the present invention only to the belt on the tread side.

Example 2 Radius for truck / bus of size 10.00 R20 shown in FIG.
Fig. 9 (b) shows the belt 2 for tread reinforcement of Altire.
Applying a belt, the test tire has an internal pressure of 7.00kgf / cm ²,load
Drum testing machine under the condition of 2600kg, speed 60km / h
After running 100,000 km, dissect and near the width edge of the belt
The crack length that occurred was measured and the results are shown in Table 2. Na
Incidentally, also in FIG. 9, a position separated by a few mm from the width end of the belt 2.
A cross section orthogonal to the axial direction of the reinforcing element is shown.

[0026]

[Table 2]

Here, the belt 2 is made up of four laminated layers in this example, and the reinforcing elements of each layer are 18 ° left and 18 ° left from the tread side, respectively.
It is inclined with respect to the tire equatorial plane at °, 18 ° to the right and 50 ° to the right. The above-mentioned cracks generated near the belt width edge are generated only in the second layer from the tread side, and therefore the measurement result is also only in that layer. Based on this fact, it is of course possible to use the rubberized layer of the present invention only for the second layer from the tread side.

Embodiment 3 Regarding the carcass ply 5 of the radial tire 1 for trucks and buses of size 11/70 R22.5 whose cross section is shown in FIG. Various arrangements of reinforcing elements when using the carcass ply described above, in contrast to FIGS. 11 to 14,
The cross section orthogonal to the axial direction of the reinforcing element at a position separated by several mm from the end of the folded portion of the carcass ply 5 is illustrated, and 3 is a reinforcing element and 4 is a bundle thereof. In FIG. 10, 6 is a folded portion of the carcass ply 5, 7 is a bead core, and 8 is a bead portion reinforcing layer.

The carcass ply 5 is the upper stage of each of FIGS. 11 to 14.
In the conventional example shown in (a), the reinforcing elements are arranged at equal intervals s in the rubberized layer, while the lower layers are also the same.
As shown in (b), which is a different case of the present invention, the division bundles 4 for every several reinforcing elements 3 are arranged at a spacing δ wider than the regular spacing s. In the example of FIG. 13 (b), the bundles 4 and 4'show the case where the number of the reinforcing elements 3 is alternately different.

Each of the test tires 1 shown in Table 3 below, which were made by trial using the reinforcing elements having different cord types according to the above-mentioned conditions, were subjected to a drum tester under the conditions of an internal pressure of 8.0 kgf / cm ² and a load of 3000 kg. The vehicle traveled at a speed of 80 km / h, the traveling distance when the carcass ply was cracked and the traveling became impossible, and the measurement results are shown in Table 3 as a ratio to the conventional example.

In contrast to the conventional example shown in the upper part (a) of FIG. 15, an example in which more than half of the entire circumference is divided into a bundle is shown in FIG. 15 (b), and less than half of the entire circumference is divided into a bundle. Examples of such cases are shown in Fig. 15 (c). The results are shown in Table 4.

[0032]

[Table 3]

[0033]

[Table 4]

Example 4 Radial for passenger cars of size P235 / 75 SR15 shown in FIG.
Carcass ply 5 of the ear carcass shown in Figures 17 and 18
Applying ply to the tire under test with internal pressure of 2.0 kgf / cm ²,load
Drum testing machine under the condition of 1450kg, speed 60km / h
When the carcass ply is run, the carcass ply becomes cracked and cannot run.
The measured distance is measured and the measurement result is used as a conventional example.
Table 5 shows the corresponding ratio. Note that the odor
However, a few mm away from the end of the folded back part of the carcass ply 5.
A cross section orthogonal to the axial direction of the reinforcing element at different positions is shown.

[0035]

[Table 5]

Example 5 As a bead reinforcing layer 8 of a radial tire 1 for trucks and buses of size 11/70 R22.5 whose cross section is shown in FIGS. ,
Various arrays of reinforcing elements in the case of using the bead portion reinforcing layer described above in relation to the present invention, in contrast to FIGS.
At 24, the end surface of the bead portion reinforcing layer 8 on the outer side in the tire radial direction is illustrated, and 3 is a reinforcing element and 4 is a bundle thereof. Fig. 19 and
In FIG. 20, 5 is a carcass ply, 6 is a folded portion thereof, and 7 is a bead core, and the tire of FIG. 20 is an example in which an additional reinforcing layer 9 of steel cord for reinforcing the carcass ply 5 is further arranged. Note that FIGS. 21 to 24 are shown in a cross section in which several millimeters are spaced inward from the radially outer end of each bead portion reinforcing layer.

The bead portion reinforcing layer 8 is the upper stage of each of FIGS.
In the conventional example shown in (a), the arrangement of the organic fibers in the rubberized layer is at equal intervals s, but the lower layers are the same.
As shown in (b), a different example of the present invention, the bundles 4 of the reinforcing elements 3 are arranged at intervals δ wider than the equal interval s.

Each of the test tires 1 shown in Table 6 below, which were made by trial using the reinforcing elements having different cord types according to the above-mentioned conditions, were subjected to a drum tester under the conditions of an internal pressure of 7.5 kgf / cm ² and a load of 3000 kg. After running for 60,000 km at a speed of 60 km / h, dissection was performed, the crack length generated near the end surface of the bead reinforcing layer 8 on the outer side in the tire radial direction was measured, and the results are shown in Table 6 together. . 23 and 24 are examples that can be further implemented based on the present invention.

[0039]

[Table 6]

Example 6 A bead portion reinforcing layer having an end face on the outer side in the tire radial direction shown in FIG. 26 is applied to the bead portion reinforcing layer 8 of a radial tire for passenger cars of size 195/75 R14 whose cross section is shown in FIG. The test tire was subjected to a drum tester under the conditions of an internal pressure of 2.0 kgf / cm ² and a load of 600 kg, run at a speed of 80 km / h for 60,000 km, and then dissected to determine the tire diameter of the bead reinforcement layer 8. The crack length generated near the end face on the outer side in the direction was measured, and the results are shown in Table 7. Note that FIG. 27 is an example that can be further implemented based on the present invention. Also in FIGS. 26 and 27,
It is shown by a cross section that is separated from the radially outer end of each bead portion reinforcing layer toward the inside by several mm.

[0041]

[Table 7]

[0042]

EFFECTS OF THE INVENTION According to the present invention, it is possible to effectively prevent the growth of cracks near the end of the reinforcing element of the constituent material, which is the cause of the separation at the end of various constituent materials, which has been regarded as a weak point of the pneumatic tire. You can

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a test tire for passenger cars.

FIG. 2 is a comparative view of a reinforcing element array.

FIG. 3 is a comparative view of a reinforcing element array.

FIG. 4 is a comparative view of a reinforcing element array.

FIG. 5 is a comparative view of a reinforcing element array.

FIG. 6 is a comparative view of a reinforcing element array.

FIG. 7 is a comparative view of a reinforcing element array.

FIG. 8 is a cross-sectional view of a test tire for trucks and buses.

FIG. 9 is a comparative view of a reinforcing element array.

FIG. 10 is a cross-sectional view of a test tire for trucks and buses.

FIG. 11 is a comparative view of a reinforcing element array.

FIG. 12 is a comparative view of a reinforcing element array.

FIG. 13 is a comparative view of a reinforcing element array.

FIG. 14 is a comparative view of a reinforcing element array.

FIG. 15 is a comparative diagram of a reinforcing element array.

FIG. 16 is a cross-sectional view of a test tire for passenger cars.

FIG. 17 is a comparative view of a reinforcing element array.

FIG. 18 is a comparative view of a reinforcing element array.

FIG. 19 is a cross-sectional view of a test tire for trucks and buses.

FIG. 20 is a cross-sectional view of a test tire for trucks and buses.

FIG. 21 is a comparison diagram of a reinforcing element array.

FIG. 22 is a comparative diagram of a reinforcing element array.

FIG. 23 is a comparative view of a reinforcing element array.

FIG. 24 is a comparative view of a reinforcing element array.

FIG. 25 is a cross-sectional view of a test tire for passenger cars.

FIG. 26 is a comparative view of a reinforcing element array.

FIG. 27 is a diagram showing a reinforcing element array.

[Explanation of symbols]

 1 Tire 2 Belt for Tread Reinforcement 3 Reinforcement Element 4 Bundle 5 Carcass Ply 6 Folding Part 7 Bead Core 8 Bead Part Reinforcing Layer 9 Additional Reinforcing Layer

Continuation of front page (31) Priority claim number Japanese Patent Application No. 4-62194 (32) Priority date Hei 4 (1992) March 18 (33) Priority claiming country Japan (JP) (31) Priority claim number Special Japanese Patent Application No. 4-62195 (32) Priority Date 4 (1992) March 18 (33) Priority Claim Country Japan (JP) (31) Priority Claim Number Japanese Patent Application No. 4-62196 (32) Priority Date 4 (1992) March 18 (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 5-6150 (32) Priority Day 5 (1993) January 18 (33) Priority Claiming country Japan (JP)

Claims (11)

[Claims] 1. A pneumatic tire having a rubberized layer composed of a predetermined number of reinforcing elements arranged in parallel with each other as a constituent material, wherein at least 30% of the reinforcing elements arranged in the rubberized layer are within several It is characterized in that it is divided into a bundle, and the dispersion interval between the bundle and the reinforcing elements adjacent thereto is wider than that in the case where the predetermined number of the reinforcing elements are arranged at equal intervals in the rubberized layer. Pneumatic tires. 2. The tire according to claim 1, wherein the constituent material is a belt used for reinforcing the tread of the tire. 3. The tire according to claim 2, wherein the reinforcing element of the belt is an organic fiber. 4. The tire according to claim 1, wherein the constituent material is a carcass ply having at least one layer wound around a pair of bead cores from inside to outside of the tire. 5. The tire according to claim 4, wherein the reinforcing element of the carcass ply is organic fiber or steel. 6. The at least one bead portion reinforcing layer extending along the folded portion of a carcass ply folded from the inside to the outside of a tire around a pair of bead cores, wherein the constituent material is at least one bead reinforcing layer. The tire described in. 7. The tire according to claim 6, wherein the reinforcing element of the bead portion reinforcing layer is an organic fiber. 8. The tire according to claim 1, wherein the bundle comprises the same number of reinforcing elements. 9. A tire according to any one of claims 1 to 7, wherein the bundle comprises reinforcing elements of different numbers. 10. At least some of the reinforcing elements adjacent to each other in the bundle are arranged in contact with each other.
The tire according to any one of 1. 11. The tire according to claim 1, wherein the gaps between the adjacent reinforcing elements in the bundle are arranged to be narrower than the distribution gap of the bundle.