JPH08216618A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE: To improve radial run out(RRO) property, while holding high speed resistance so as to suppress generation of vibration. CONSTITUTION: The present invention relates to a pneumatic radial tire provided with a radially arranged carcass 6 which passes from a tread part 2 along the side wall part 3 and turns back around the bead core 5 of a bead part 4, and provided with a belt layer 7 arranged inside of the tread part and also arranged outward in radial direction of the carcass, wherein this radial tire has a band layer 9 consisting of at least one sheet of band ply in which band cords made of organic or inorganic fibers and arranged approximately in parallel to the tire equator, is arranged between the carcass and a belt layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of suppressing high-speed running-induced vibrations due to the band layer during high-speed running and preventing uneven wear while maintaining high-speed durability.

[0002]

2. Description of the Related Art In recent years, as the performance of vehicles has increased, tires mounted on the vehicles have been strongly required to have durability and steering stability in a high speed range. Normally, as the tire speed increases, the centrifugal force acting on the tire increases,
The tread circumference tends to widen. For this reason, during high-speed running, the shape of the tread surface is different from that during stationary and low-speed running, so that high-speed running stability and high-speed durability are often impaired.

Moreover, at high speeds, the radial increase due to the centrifugal force is greater than that at the center of the tread at both sides of the belt layer where the restraint force by the belt layer is relatively small. Wear tends to occur in the shoulder portion. Therefore, conventionally, in order to solve these problems, a band layer has been provided outside the belt layer.

[0004]

The band layer is formed as shown in FIG.
As shown in FIG. 5, the band ply b in which the band cords d are arranged substantially parallel to the equator of the tire is formed by the sheet body in which the ends e and e are overlapped and wound on the belt layer. Therefore, the band layer thus formed has the overlapping portions f where the edges e of the sheet body overlap.

Further, since the band layer is wound on the belt layer, it is easily affected by the overlapping portion f, and the radial runout (RRO) is deteriorated. In particular, the waveform of RRO is abnormal at the overlapping portion f. In this state, a protruding state occurs, which causes an increase in vibration during traveling and uneven wear.

Further, by winding the band ply on the belt layer, the end portion of the belt layer hangs down, and by filling the internal pressure of the tire, the shoulder portion tends to fall over the shoulder, and the shoulder portion becomes early. There is a risk of wear.

As a result of repeated research and trial manufacture for solving such a problem, the inventor has found that the problem can be solved by interposing a band layer between the carcass and the belt layer, thereby completing the present invention. I made it.

It is an object of the present invention to provide a pneumatic radial tire capable of suppressing vibrations that tend to occur during high speed running and preventing early wear of the shoulder portion while maintaining the high speed durability.

[0009]

According to the present invention, there is provided a carcass in a radial arrangement in which a tread portion passes through a sidewall portion and is folded back around a bead core of a bead portion, and the carcass is arranged inside the tread portion and radially outside the carcass. A pneumatic radial tire including a belt layer, comprising: at least one band ply in which band cords made of organic or inorganic fibers are arranged substantially parallel to a tire equator between the carcass and the belt layer. The pneumatic radial tire is characterized by arranging the following band layers.

The band ply can be formed by winding the sheet body on the carcass one or more times with an overlapping part where the ends overlap, and further, a band-shaped cord or a band-shaped coated with a topping rubber. It may be formed by spirally winding the elongated body in the tire circumferential direction.

The band layer may be formed by a full width band ply which overlaps the belt layer over substantially the entire surface, or may be formed by a small width band ply arranged at both ends of the belt layer in the tire axial direction. Alternatively, the band ply having the full width and the band ply having the small width may be included.

[0012]

The band layer is formed by a band ply in which band cords made of organic or inorganic fibers are arranged substantially parallel to the tire equator. As a result, even during high-speed running, lifting of the tread surface due to centrifugal force and RRO can be suppressed, and high-speed durability can be maintained.

Further, the band layer is arranged between the carcass and the belt layer. Therefore, in the band ply forming the band layer, the outer side in the radial direction is covered with the belt layer, and therefore even when formed as a sheet body, the overlapping portion is inside the belt layer, and the influence of the overlapping portion is exerted. The influence on the tread surface is small, and it is possible to suppress the phenomenon that the RRO locally rises abnormally on the tread surface corresponding to the overlapping portion, that is, the occurrence of so-called pitting. As a result, vibrations that tend to occur during high-speed running can be reduced, steering stability and riding comfort can be enhanced, speeding up of the tires can be promoted, and uneven wear that tends to occur at overlapping portions can be suppressed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2, the pneumatic radial tire 1 is
It has a tread portion 2, a pair of sidewall portions 3 extending inward in the tire radial direction from both sides thereof, and a bead portion 4 extending inward of the sidewall portion 3.

Further, in the pneumatic radial tire 1, a folded-back portion is formed by folding back around the bead core 5 from the inner side in the tire axial direction to the main body portion 6a extending from the tread portion 2 to the sidewall portion 3 to the bead portion 4. The carcass 6 includes a carcass 6b and a belt layer 7 disposed outside the carcass 6 and inside the tread portion 2. A band layer 9 is arranged between the carcass 6 and the belt layer 7.

In this embodiment, the carcass 6 has a body portion 6a and a folded portion 6b radially outward of the bead core 5.
A bead apex 8 having a triangular cross section and made of hard rubber is erected between and.

In the present embodiment, the carcass 6 is composed of one carcass ply, and the carcass ply has a carcass cord made of organic fibers such as nylon, polyester, rayon, and aromatic polyamide at 75 with respect to the tire equator C. It is formed as a radial or semi-radial array juxtaposed at an angle of ~ 90 °.

In this example, the belt layer 7 is composed of an inner belt ply 7A on the inner side in the tire radial direction and an outer belt ply 7B on the outer side. Each of the belt plies 7A and 7B is made of nylon, polyester, rayon or aromatic. A belt cord made of an organic fiber such as polyamide or a steel cord is tilted at an angle of 10 to 45 ° with respect to the tire equator C, and the belt plies 7A and 7B are arranged so as to intersect each other.

In this embodiment, the inner belt ply 7A is formed to be slightly wider than the outer belt ply 7B, and the inner ply width of the inner belt ply 7A, that is, the belt width of the wider belt ply. WB is tread width W
It is formed to be 0.8 to 1.1 times as large as T.

The band layer 9 is a sheet member 13 in this embodiment.
The band ply 10 is formed by rotating the band ply 10 on the carcass 6 once and then winding the sheet body 13 so that both end portions E, E in the circumferential direction have overlapping portions F overlapping each other.
Further, the band width WD1 of the band ply 10 in the axial direction of the tire is formed as the band width 14 having the same width as the belt width WB which is the ply width of the inner belt ply 7A.

In this example, the band layer 9 is formed by stacking two band plies 14 having such a full width inside and outside in the radial direction.

The band ply 10 is made of organic fiber such as nylon, rayon, polyester, aromatic polyamide or the like or inorganic fiber such as glass fiber at an angle of 0 to 5 degrees with respect to the tire equator C, that is, substantially with respect to the tire equator. It is formed by covering the band cords 11 arranged in parallel with a topping rubber.

As shown in FIG. 3, the band ply 10 includes one or a plurality of band plies, and in this example, two band cords 21,
Alternatively, the cord-shaped or strip-shaped elongated body 17 in which 21 is covered with the topping rubber 22 may be spirally wound on the carcass 6 substantially parallel to the tire equator C.

FIG. 4 shows another mode of the band layer 9. FIG.
(A) shows the band layer 9 formed by the narrow band plies 15 arranged at both ends of the belt layer 7 in the axial direction of the tire.
The mode which formed is shown. In this example, the edge K on the outer side in the tire axial direction of the narrow band ply 15 is made substantially coincident with the edge L of the belt layer 7 in the width direction, while the band width WD2 of the narrow band ply 15 is set to the belt. Width WB 0.1 to 0.1
It is preferably 0.3 times. Further, in this example, the band layer 9 is formed by stacking two small and narrow band plies 15 inside and outside.

When the band layer 9 is formed by the band ply 15 having a small width as described above, the shoulder region 2S of the tread portion 2 is more lifted than the central region 2C due to internal pressure filling or high speed running. Can be effectively prevented, the ground contact pressure of the shoulder region 2S can be suppressed from increasing, and high-speed durability and uneven wear resistance of the shoulder region 2S can be enhanced.

Further, as shown in FIG. 4B, a band layer may be formed by superposing the full width band ply 14 of the above construction and the pair of small width band plies 15 and 15 of the above construction. The present invention can be modified into various aspects.

[0027]

SPECIFIC EXAMPLE Tires having a tire size of 265/70 R15 and having the configuration shown in FIG. 1 or FIGS. 4A and 4B (Tables 1 and 3 for Examples 1 to 3 and 11 to 13).
A prototype was made according to the specifications shown in Table 2 and its performance was tested. The tires having the band layer and the belt layer (Comparative Examples 1 to 3 and 11 to 13) were also tested to compare their performances.

(1) Radial run-out (RRO) The radial run-out amount and the peak value (piyoco) at the overlapping portion of the band ply were measured for each of 10 test tires, and the average value was obtained. In addition, the piyoko is indicated by an index with 100 corresponding to each comparative example. The smaller the number, the better.

(2) High-speed durability Using a drum tester, each test tire was tested with 15 ″ × 8JJ
Mounted on the rim of the car and under an internal pressure of 2.85 kgf / cm ² 8
Performed in accordance with the load / speed performance test method stipulated in ECE30 by applying a load of 48 kg, increasing the running speed one by one by the step speed method, and judging by the speed when cracks occur in the tread part and each response The comparative example is represented by an index of 100. The larger the index, the better. In each example,
In each of the comparative examples, five samples are measured and the average value is shown.

(3) Amount of uneven wear in shoulder area Each test tire was mounted on an actual vehicle under an internal pressure of 2.0 kgf / cm ² , and the vehicle was run for 30,000 km. The difference in the amount of abrasion was measured, and each index was displayed as an index with 100 being the corresponding comparative example. The larger the value, the better.

[0031]

[Table 1]

[0032]

[Table 2]

As a result of the test, it was confirmed that each of the examples can reduce the radial runout and increase the uneven wear resistance while maintaining the high speed durability as compared with the corresponding comparative example.

[0034]

As described above, the pneumatic tire of the present invention is
Since the gist of the band layer is between the carcass and the belt layer, radial runout can be reduced without lowering high-speed durability, vibration that tends to occur during high-speed running is suppressed, and uneven wear Can be prevented, and high-speed driving performance can be improved.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing an example of a band ply forming a sheet body.

FIG. 3 is a perspective view showing an example of a long body.

4 (A) and 4 (B) are partial cross-sectional views showing another embodiment.

5 (A), (B), and (C) are sectional views showing a conventional technique.

[Explanation of symbols]

 2 tread part 3 sidewall part 4 bead part 5 bead core 6 carcass 7 belt layer 9 band layer 10 band ply 11, 21 band cord 13 sheet body 14 full width band ply 15 narrow band ply 17 long body C tire equator E Edge F Overlapping part

Claims (6)

[Claims] 1. A pneumatic tire comprising a carcass of a radial arrangement in which a tread portion passes through a sidewall portion and is folded back around a bead core of a bead portion, and a belt layer disposed inside the tread portion and radially outside the carcass. A radial tire, wherein a band layer made of at least one band ply in which band cords made of organic or inorganic fibers are arranged substantially parallel to the tire equator is arranged between the carcass and the belt layer. A characteristic pneumatic radial tire. 2. The air according to claim 1, wherein the band ply is formed by winding a sheet body one or more times with an overlapping portion whose ends overlap each other on a carcass. Radial tires with. 3. The band ply is formed by spirally winding a cord-shaped or band-shaped elongated body obtained by coating a band cord with a topping rubber in a tire circumferential direction on a carcass. 1. The pneumatic radial tire described in 1. 4. The pneumatic radial tire according to claim 1, wherein the band layer includes a full-width band ply that overlaps the entire surface of the belt layer. 5. The pneumatic radial tire according to claim 1, wherein the band layer comprises narrow band plies arranged at both ends of the belt layer in the tire axial direction. 6. The pneumatic radial tire according to claim 5, wherein the band layer includes the full-width band ply and the narrow-width band ply.