JP4382227B2 - Pneumatic tire - Google Patents

Description

【００２５】
実施例１〜３、比較例１〜４及び従来例の各タイヤを供試タイヤとし、これらタイヤを適用リムのうちの標準リム９．００×２２．５に装着し、これに最高空気圧９００kPa を充てんし、これらタイヤ及びリム組立体は、最大負荷能力の１．９倍に相当する荷重６６．１５ｋＮの負荷下で、速度６０km/hで回転するドラムに押し当て、ベルトに故障が生じるまでの走行距離を測定した。測定結果は従来例タイヤを１００とする指数にてあらわし、表１にこれら指数を記載した。値は大なるほど良い。
【００２６】
表１から、実施例１〜３のタイヤは、従来例タイヤ対比、いずれもベルト耐久性が大幅に向上していること、これに対し、適正値範囲外の比較例１〜４のタイヤは、ベルト耐久性向上が小幅に止まっていることが分かる。
【００２７】
【発明の効果】
この発明の請求項１〜５に記載した発明によれば、重荷重負荷転動の下でのベルト耐久性が大幅に向上する空気入りタイヤを提供することができる。
【図面の簡単な説明】
【図１】 この発明の空気入りタイヤの左半断面図である。
【符号の説明】
１ 空気入りタイヤ
２ トレッド部
３ サイドウォール部
４ ビード部
５ ビードコア
６ ラジアルカーカス
７ ベルト
７w-1 、７w-2 波形コード巻回層
７c-1 、７c-2 コード交差層
Ｅ タイヤ赤道面
Ｍ ラジアルカーカス最大幅位置
ＣＷmax ラジアルカーカス最大幅
ＢＷc コード交差層最大幅
ＢＷw 波形コード巻回層最大幅[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire, and more particularly to a pneumatic radial tire for use in heavy vehicles such as trucks and buses, and particularly to a pneumatic tire with improved belt durability.
[0002]
[Prior art]
In particular, the pneumatic radial tire used in the above-described vehicle is likely to fail in the belt because it is used under a heavy load for a long period of time. Therefore, as a means for improving the durability of the belt, a conventional type of multiple layers, for example, two layers, is used. Corrugated cords (called "Wavy cords") arranged outside the cord crossing layer along the tire equator plane, or with a slight inclination of 1 ° or less with respect to the equator plane A belt structure in which a plurality of cord winding layers are arranged is used.
[0003]
[Problems to be solved by the invention]
It has been confirmed that this belt structure exhibits superior durability as compared with the belt structure having only the cord crossing layer. However, in recent years, as the flattening of tires has further progressed and the load applied to the tire cavities has increased, the shortage of belt durability has become conspicuous even in radial tires having this type of belt structure.
[0004]
Accordingly, an object of the present invention described in the first to fifth aspects of the present invention is to provide a pneumatic tire having a belt durability that can sufficiently cope with recent tire flattening tendency and high load load conditions.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 of the present invention has a tread portion, a pair of sidewall portions and a pair of bead portions connected to both sides thereof, and one ply or more for reinforcing these portions. In a pneumatic tire provided with a radial carcass and a belt composed of four or more rubber-coated cord layers that reinforce the tread portion on the outer periphery of the radial carcass,
The belt has two or more cord crossing layers and 2 to 4 corrugated cord winding layers,
The corrugated cord winding layer is located on the inner side in the tire radial direction of the cord crossing layer,
The cord crossing layer, at least one of which has a maximum width in the range of 70-90% of the maximum width of the radial carcass;
The pneumatic tire is characterized in that a value obtained by subtracting the maximum width of the corrugated cord winding layer from the maximum width of the cord crossing layer is in a range of 20 to 50 mm.
[0006]
Here, the maximum width of the radial carcass follows the definition described below. That is, according to the measurement method of new tires of the tire standards established by the country such as JATMA YEAR BOOK (1999), the prescribed tire is mounted on the applicable rim, and the maximum air pressure (the air pressure corresponding to the maximum load capacity) is set to room temperature (15- (30 ° C) for 24 hours, and then adjust to the original air pressure and measure again. When it is difficult to measure the maximum width of the radial carcass, a value obtained by subtracting the rubber thickness from the tire cross-sectional width may be used.
[0007]
Regarding the invention described in claim 1, as in the invention described in claim 2, each cord of the cord crossing layer and the corrugated cord winding layer is made of a steel cord having one or more strands.
[0008]
As for the invention described in claims 1 and 2, each layer of the corrugated cord winding layer has a uniform width as in the invention described in claim 3, and the corrugated as in the invention described in claim 4. The cord winding layer has one of a spiral winding configuration of one or more corrugated cords and an overlapping configuration of a plurality of corrugated cord arrangement layers along the tire equatorial plane.
[0009]
Moreover, regarding the invention described in claims 1 to 4, as in the invention described in claim 5, the cord of the cord crossing layer has an inclination angle within a range of 30 to 60 ° with respect to the tire equatorial plane.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to FIG.
FIG. 1 is a left half sectional view of a pneumatic tire according to the present invention.
In FIG. 1, a pneumatic tire (hereinafter referred to as a tire) 1 includes a tread portion 2, a pair of sidewall portions 3 (shown only on one side) and a pair of bead portions 4 (shown only on one side). ). Reference numeral E denotes a tire equator plane.
[0011]
The tire 1 has one or more plies that reinforce each of the parts 2 to 4 between the bead cores 5 embedded in the bead parts 4. In the illustrated example, the radial carcass 6 of one ply and the tread part 2 on the outer periphery of the radial carcass 6 are shown. And a belt 7 to be reinforced.
[0012]
The belt 7 has two or more layers, in the illustrated example, two cord crossing layers 7c-1 and 7c-2, and two to four layers, and in the illustrated example, two corrugated cord winding layers 7w-1 and 7w-2 And have. The cord crossing layers 7c-1 and 7c-2 are layers in which straight cords cross each other with the tire equatorial plane E in between. On the other hand, the corrugated cord winding layers 7w-1 and 7w-2 are arranged in a plane parallel to the tire equator plane E, where the winding of the cord (wavy cord) attached to the corrugation in the width direction of the belt 7 is located. Or a winding arrangement that is tilted slightly less than 1 ° with respect to the plane.
[0013]
Here, the corrugated cord winding layers 7w-1 and 7w-2 are positioned inward in the radial direction (hereinafter referred to as the radial direction) of the tire 1 of the cord crossing layers 7c-1 and 7c-2. Further, at least one of the cord crossing layers 7c-1 and 7c-2, and in the illustrated example, one cord layer 7c-1 passes through the maximum width position M of the radial carcass 6 by the width CWmax (described above). (According to the definition) having a width BWc in the range of 70 to 90%, this width BWc forms the maximum width of the cord crossing layers 7c-1 and 7c-2.
[0014]
The value obtained by subtracting the maximum width BWw of the corrugated cord winding layers 7w-1 and 7w-2 from the maximum width BWc of the cord crossing layers 7c-1 and 7c-2 is set in the range of 20 to 50 mm. That is, the corrugated cord winding layers 7w-1 and 7w-2 are completely covered by one of the cord crossing layers 7c-1 and 7c-2 having the maximum width BWc, in this example, the cord layer 7c-1. And Each cord layer of the belt 7 is preferably divided into two halves by the tire equatorial plane E. In this case, as shown in FIG. 1, the edge of the cord layer 7c-1 and the corrugated cord winding layer 7w-1 , 7w-2, the distance Dw between the end of the cord layer having the maximum width BWc is 10 to 25 mm.
[0015]
In the tire 1 having the configuration of the belt 7 described above, the cord crossing layers 7c-1 and 7c-2 suppress the elongation of the corrugated cord winding layers 7w-1 and 7w-2 and are corrugated under a predetermined internal pressure. Since the cord winding layers 7w-1 and 7w-2 are arranged at the center of the tread portion 2, the amount of radial growth of the belt 7 can be made uniform over the entire width of the belt 7, here the maximum width BWc. . Due to uniform growth over the entire width of the belt 7, the durability of the belt is greatly improved. This is because the belt durability depends on the growth amount at the ends of the cord crossing layers 7c-1 and 7c-2, and the larger the growth amount at the ends, the lower the belt durability. This is because durability is improved and uniform growth reduces the growth amount of the end portion while increasing the growth amount of other portions except the end portion.
[0016]
Here, if the maximum width BWc of the cord crossing layers 7c-1 and 7c-2 is less than 70% of the maximum width CWmax of the radial carcass 6, when the tread portion 2 is cut and damaged, the cut scratches are formed on the radial carcass 6. If it exceeds 90%, the effect of uniform growth over the entire width of the belt 7 is diminished, and a separation failure is likely to occur at the ends of the cord crossing layers 7c-1 and 7c-2. So neither is possible.
[0017]
If the value obtained by subtracting the maximum width BWw from the maximum width BWc is less than 20 mm, a separation failure occurs between the cord crossing layers 7c-1 and 7c-2 and the end portions of the corrugated cord winding layers 7w-1 and 7w-2. Since it becomes easy to generate | occur | produce and the uniformity of a growth amount will become inadequate if it exceeds 50 mm, neither is impossible.
[0018]
In practice, the above effect is remarkable when steel cords having one or more strands are applied to the cord intersection layers 7c-1 and 7c-2 and the corrugated cord winding layers 7w-1 and 7w-2. It becomes.
[0019]
Further, as shown in FIG. 1, each of the corrugated cord winding layers 7w-1 and 7w-2 has a uniform width BWw. In this case, it is preferable to match the edges. The same applies when the corrugated cord winding layers are three layers and four layers.
[0020]
The corrugated cord winding layers 7w-1 and 7w-2 are configured by spiral winding of one or more corrugated cords, or a large number of corrugated cord array layers along a plane parallel to the tire equatorial plane E. Are configured to overlap in the circumferential direction of the tread portion 2, or any configuration is acceptable.
[0021]
Further, arranging the cords of the cord crossing layers 7c-1 and 7c-2 at an inclination angle within a range of 30 to 60 ° with respect to the tire equator plane E contributes to improvement in belt durability.
[0022]
【Example】
Radial ply tires for trucks and buses having a size of 315 / 60R22.5, and tires of Examples 1 to 3 according to FIG. 1 were prepared. Steel cords were all applied to the ply cord of the radial carcass 6, the corrugated cord winding layers 7w-1 and 7w-2 of the belt 7, and the cords of the cord crossing layers 7c-1 and 7c-2. The corrugated cord winding layers 7w-1 and 7w-2 are cord spiral winding layers having the same width BWw, and the inclination angle of the cord crossing layers 7c-1 and 7c-2 with respect to the tire equatorial plane E is 38 °.
[0023]
On the other hand, the tires of Comparative Examples 1 to 4 outside the compatible numerical value range and the conventional tire in which the corrugated cord winding layer is arranged outside the cord crossing layer were prepared. The ratio of the cord crossing layer 7c-1 width (maximum width) BWc to the maximum width CWmax of the radial carcass 6 (BWc / CWmax) × 100 (%) of these tires and the cord cord winding from the cord crossing layer 7c-1 width BWc Table 1 shows the value (mm) of (BWc−BWw) obtained by subtracting the width BWw of the layers 7w-1 and 7w-2.
[0024]
[Table 1]

[0025]
The tires of Examples 1 to 3, Comparative Examples 1 to 4 and the conventional example are used as test tires, and these tires are mounted on a standard rim 9.00 × 22.5 of the applicable rims, and the maximum air pressure is 900 kPa. These tires and rim assemblies are pressed against a drum rotating at a speed of 60 km / h under a load of 66.15 kN corresponding to 1.9 times the maximum load capacity until the belt fails. The mileage was measured. The measurement results are expressed as indices with the conventional tire as 100, and these indices are shown in Table 1. The higher the value, the better.
[0026]
From Table 1, the tires of Examples 1 to 3 are significantly improved in belt durability compared to the conventional tires, whereas the tires of Comparative Examples 1 to 4 outside the appropriate range are It can be seen that the improvement in belt durability is limited.
[0027]
【The invention's effect】
According to the first to fifth aspects of the present invention, it is possible to provide a pneumatic tire in which belt durability under heavy load rolling is greatly improved.
[Brief description of the drawings]
FIG. 1 is a left half sectional view of a pneumatic tire according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Radial carcass 7 Belt 7w-1, 7w-2 Corrugated cord winding layer 7c-1, 7c-2 Cord crossing layer E Tire equatorial plane M Radial carcass Maximum width position CWmax Maximum radial carcass width BWc Maximum width of cord crossing layer BWw Maximum width of corrugated cord winding layer

Claims (5)

It has a tread part, a pair of sidewall parts and a pair of bead parts connected to both sides thereof, a radial carcass of one ply or more that reinforces each part, and four or more layers that reinforce the tread part on the outer periphery of the radial carcass In a pneumatic tire provided with a belt made of a rubber-coated cord layer,
The belt has two or more cord crossing layers and 2 to 4 corrugated cord winding layers,
The corrugated cord winding layer is located on the inner side in the tire radial direction of the cord crossing layer,
The cord crossing layer, at least one of which has a maximum width in the range of 70-90% of the maximum width of the radial carcass;
A pneumatic tire characterized in that a value obtained by subtracting the maximum width of the corrugated cord winding layer from the maximum width of the cord crossing layer is in a range of 20 to 50 mm. The tire according to claim 1, wherein each cord of the cord crossing layer and the corrugated cord winding layer is made of a steel cord having one or more strands. The tire according to claim 1 or 2, wherein each layer of the corrugated cord winding layer has a uniform width. The corrugated cord winding layer has any one of a spiral winding configuration of one or more corrugated cords and an overlapping configuration of a plurality of corrugated code array layers along the tire equatorial plane. The tire described in item 1. The tire according to any one of claims 1 to 4, wherein the cord of the cord crossing layer has an inclination angle within a range of 30 to 60 ° with respect to the tire equatorial plane.

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