JP4612181B2 - Pneumatic tire - Google Patents

Description

【００３１】
【発明の効果】
以上説明したように、本発明の空気入りタイヤは、バンドのタイヤ軸方向の外端を、最大巾ベルトプライのタイヤ軸方向の外端よりもタイヤ軸方向内側で終端させているため、よりシビアな高負荷走行条件下においても、最大巾のベルトプライの外端の端面とバンドとが接触することを防止でき、従来このような接触が原因で生じていた最大巾のベルトプライ外端でのゴム剥離を抑制しうる結果、一般耐久性を大巾に向上しうる。
【図面の簡単な説明】
【図１】 本発明の実施形態を示すタイヤ（バンドを除く）の断面図である。
【図２】そのベルトプライの外端付近の拡大図である。
【図３】その略図である。
【図４】 参考例を示すベルトプライの外端付近の略図である。
【図５】（Ａ）、（Ｂ）は本発明の他の実施形態を示すベルトプライの外端付近の略図である
【図６】本発明の他の実施形態を示すベルトプライの外端付近の略図である
【図７】ベルトプライの外端付近の略図である
【図８】従来のバンドを示すトレッド部の断面図である。
【図９】その略図である
【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 カーカス
７ ベルト層
７Ａ 最大巾ベルトプライ
７Ｂ 外のベルトプライ
７Ａｅ、７Ｂｅ ベルトプライの外端
９ バンド
９ｅ バンドの外端[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire that can improve high-speed durability.
[0002]
[Prior art and problems to be solved by the invention]
With the recent high performance of vehicles and the development of highway networks, improvement of high-speed durability is also strongly desired for pneumatic tires. In general pneumatic radial tires, for example, as shown in FIG. 8, a belt layer b made of two belt plies b1 and b2 made of, for example, a steel cord, for fastening a toroidal carcass a is provided. However, the outer end be of the widest belt ply b1 has the most movement and the strain is concentrated in the tire due to repeated ground contact (when loaded) and ungrounded (no load) associated with high speed running of the tire. Part. Accordingly, most of the damage caused by the high-speed running is concentrated on the outer end be of the belt ply b1 having the maximum width, and there is an urgent need to improve the durability of the portion.
[0003]
Conventionally, in order to solve this kind of problem, optimization of the belt ply width, improvement of the cord material of the belt ply, improvement of adhesion of the pre-tapping rubber, optimization of the tread rubber thickness, and the like have been performed. However, there is a limit to the improvement by these methods. Further, in recent years, in order to suppress the movement of the outer end be of the belt ply b1, as shown in FIG. 8 and FIG. 9 which is a partially enlarged view thereof, an organic fiber cord is provided on the outer side in the tire radial direction of the belt layer b. Providing a so-called band c wound around the tire circumferential direction has been proposed. The outer end ce of the band c in the tire axial direction generally terminates at a position further beyond the outer end be of the belt ply b1 having the maximum width.
[0004]
The inventors analyzed the cause of damage under high load conditions in a tire provided with a band c in order to further improve the durability of the tire. As a result, under more severe high load conditions, the outer end ce of the band c is wound beyond the outer end be of the maximum width belt ply b1 outward in the tire axial direction. The end surface (belt cord end) of the outer end be of the belt ply b1 and the organic fiber cord of the band c are repeatedly contacted and separated, and this causes the end surface of the outer end be of the maximum width belt ply b1. From the above, it was found that rubber peeling occurred, which spread in the tire axial direction and caused belt ply edge looseness (BEL) to cause damage.
[0005]
In view of the actual situation as described above, the present invention is based on terminating the position of the outer end of the band in the tire axial direction on the inner side in the tire axial direction from the outer end of the belt ply of the maximum width in the tire axial direction. An object of the present invention is to provide a pneumatic tire that can further improve durability by preventing contact with the band at the outer end of the belt ply having the maximum width.
[0006]
[Means for Solving the Problems]
The invention according to claim 1 of the present invention includes a carcass extending from the tread portion through the sidewall portion to the bead core of the bead portion, a belt layer disposed on the outer side in the tire radial direction of the carcass and inside the tread portion, A pneumatic tire having a band in which a band cord made of organic fibers is arranged substantially in the tire circumferential direction on the outer side in the tire radial direction of the belt layer, wherein the belt layer has a maximum width in the tire axial direction. It consists of two belt plies, a belt ply of width and one outer belt ply arranged on the outer side in the tire radial direction of the belt ply of the maximum width, and the outer end of the band in the tire axial direction is The belt ends at the inner side in the tire axial direction than the outer end in the tire axial direction of the belt ply of the maximum width, and the band extends in the tire axial direction at the outer end of the outer belt ply. A portion that covers at least a part of the step portion of the maximum width belt ply between the outer end of the outer belt ply and the outer end of the maximum width belt ply by extending outward from the outer end from the inside A first band ply having a covering portion; and a second band ply that terminates inward in the tire axial direction from the outer end of the outer belt ply and overlaps the first band ply in the tire radial direction. And the axial distance L1 of the partially covered portion is 20 to 90% of the step amount S which is the length of the step portion in the tire axial direction.
[0008]
In the invention according to claim 2 , the outer belt ply is formed by covering the inner surface, the outer surface, and the end surface in the tire axial direction of the tire radial direction with a covering rubber on the end portion in the tire axial direction. the band cord of the distance between the end face is a pneumatic tire according to claim 1, characterized in that a 1.0 to 2.5 mm.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings, taking a pneumatic radial tire for passenger cars as an example. FIG. 1 is a right half sectional view of a pneumatic tire . In the figure, a pneumatic tire 1 includes a carcass 6 that extends from a tread portion 2 through a sidewall portion 3 to a bead core 5 of a bead portion 4, and a belt disposed outside the carcass 6 in the tire radial direction and inside the tread portion 2. A layer 7 and a band 9 disposed on the outer side in the tire radial direction of the belt layer 7 are provided.
[0011]
The carcass 6 includes one or more radial structures in which carcass cords are arranged at an angle of, for example, 75 ° to 90 ° with respect to the tire equator C, and in this example, one carcass ply 6A. As the carcass cord, a polyester cord is employed in this example, but other than this, an organic fiber cord such as nylon or rayon, and an aramid cord or a steel cord may be employed depending on the type of tire.
The carcass ply 6A includes a main body portion 6a that extends from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a folded portion that extends from the main body portion 6a and is folded around the bead core 5. 6b is shown, and a hard bead apex rubber 8 extending from the bead core 5 to the outside in the tire radial direction is disposed between the main body 6a and the turn-up portion 6b.
[0012]
Further, in this example, the belt layer 7 has a maximum width belt ply 7A having a maximum tire axial width BW and arranged on the inner side in the tire radial direction, and an outer side in the tire radial direction of the maximum width belt ply 7A. An example is shown in which two belt plies are combined with one outer belt ply 7B. Accordingly, the belt layer 7 includes the step portion 20 of the maximum width belt ply in which the outer end 7Ae of the maximum width belt ply 7A in the tire axial direction and the outer end 7Be of the outer belt ply 7B are displaced in the tire axial direction. Form. 2 shows an enlarged cross-sectional view of the belt ply and the like, and FIG. 3 shows a schematic view thereof. The step amount S, which is the length of the step portion 20 in the tire axial direction, is determined by the outer ends 7Ae and 7Be. In order to prevent overlap and prevent stress concentration due to a rigidity step with the rubber part, it is preferably set to, for example, 4.0 to 10.0 mm, more preferably about 6.0 to 10 mm. Here, the outer end of each ply is the outer end of the cord arranged in the ply.
[0013]
Each of the belt plies 7A and 7B is formed by covering the belt cord 14 with the topping rubber 15, and in this example, the belt cord 14 is inclined with respect to the tire equator C at a small angle of 10 to 45 °, for example. The belt cords 14 are arranged and overlapped with each other between the plies so as to cross each other. Moreover, although the steel cord is employ | adopted for the said belt cord 14 in this example, highly elastic organic fiber cords, such as aramid and rayon, can also be used as needed.
[0014]
Further, the outer end 7Be of the outer belt ply 7B of the present example is a covering rubber having an inner surface, an outer surface in the tire radial direction, and an end surface in the tire axial direction at the end portion in the tire axial direction. What was covered by 10 is illustrated. The maximum width belt ply 7A has a small thickness rubber strip 11 attached to the outer surface in the tire radial direction. With these covering rubber 10 and strip rubber sheet 11, in the finished state of the tire, the minimum belt cord distance X1 in the tire radial direction between the maximum width belt ply 7A and the outer belt ply 7B is, for example, 1.0 to 1.0. The belt cord distance X2 in the tire radial direction between the maximum width belt ply 7A and the outer belt ply 7B at the outer end 7Be of the outer belt ply can be maintained at, for example, 1.0 to 1.6 mm. It can be 1.6 mm.
[0015]
As a result, the rubber gauge in the tire radial direction between the maximum width belt ply 7A and the outer belt ply 7B is reliably and appropriately secured, so that the shearing force generated between the belt plies 7A and 7B can be relaxed and absorbed, and separation and the like can be performed. Effective to prevent.
[0016]
The band 9 is formed on the outer side of the belt layer 7 in the tire radial direction by arranging band cords 16 made of, for example, nylon, rayon, polyester, aramid, or other organic fiber coat substantially parallel to the tire circumferential direction. . The band 9 is formed in a variety of conventionally known methods, for example, a wide ply in which a large number of band cords 16 are arranged in parallel is wound around the outside of the belt layer 7 and both ends in the circumferential direction are overlapped to form an annular shape. A ply seam is formed by spirally winding a band-shaped ply in which a joint type band or a plurality of band cords 16 arranged in parallel or in parallel with a topping rubber 17 are arranged in a spiral shape along the tire circumferential direction. It can be formed of a jointless band or the like that substantially eliminates the above. The arrangement of the band cord 16 substantially parallel to the tire circumferential direction includes a case where the angle between the band cord 16 and the tire circumferential direction is 5 ° or less.
[0017]
The band 9 of the present embodiment is, for example, the jointless type band, and is configured as a so-called edge band arranged with a small width W1 (shown in FIG. 1) on the outer side in the tire radial direction of the belt layer 7 and on the shoulder portion. Things are illustrated. Such a band 9 suppresses the lifting and movement of the belt layer 7 on the shoulder side, reduces heat generation, and improves the high-speed durability of the tire. Also, since there is no ply joint, the binding force on the belt layer 7 increases. Moreover, since the uniformity of the tire is improved, it is particularly suitable for improving the durability.
[0018]
In the present invention, one of the features is that the outer end 9e of the band 9 in the tire axial direction terminates on the inner side in the tire axial direction of the outer end 7e of the maximum width belt ply 7A in the tire axial direction.
[0019]
In such a pneumatic tire 1, the belt cord 16 can be reliably prevented from coming into contact with the outer end 7 </ b> Ae of the belt ply having the maximum width that moves most during high-speed traveling. High-speed durability at high load can be improved. The band 9 extends, for example, from the inner side in the tire axial direction of the outer end 7Be of the outer belt ply 7B to the outer side of the outer end 7Be, thereby partially covering a part 21 that covers at least a part of the step part 20. It is desirable to have As a result, the band 9 can cover at least a part of the outer side in the tire radial direction of the maximum width belt ply 7A, so that the movement of the maximum width belt ply 7A can be reliably suppressed and the outside of the maximum width belt ply 7A can be prevented. Contact with the end 7Ae can be prevented.
[0020]
When the distance L1 in the tire axial direction of the partial covering portion 21 is large, the outer end 9e of the band 9 tends to approach the outer end 7Ae of the maximum width belt ply. Conversely, when the distance L1 is decreased, the belt Since the effect which suppresses the motion of the layer 7 falls relatively, it is not preferable. From this viewpoint, although not particularly limited, the distance L1 is desirably 20 to 90% of the step amount S, more preferably 50 to 90%, and still more preferably 60 to 80%.
[0021]
In addition, as shown in FIG. 7, it is conceivable to prevent the contact between the band 9 and the outer end 7Ae of the maximum width belt ply 7A by attaching a covering rubber 10 to the maximum width belt ply 7A. Practical use such as a step difference in the radial direction of the tire between the maximum width belt ply 7A and the outer belt ply 7B increases, resulting in molding defects in which air remains in the tread during vulcanization molding, and scrap is frequently generated. The top is difficult.
[0022]
Further, the outer end 7Be of the outer belt ply 7B is placed on the maximum width belt ply 7A and is a portion where the movement is relatively small even when the tire is running at a high speed compared to the outer end 7Ae of the maximum width belt ply. Is unlikely to occur. However, when the outer end 9e of the band 9 terminates between the outer end 7Ae of the maximum width belt ply and the outer end 7Be of the outer belt ply, more preferably, the band cord 16 and the outer belt ply The distance L2 between the cords in the tire axial direction of the outer end 7Be is, for example, 1.0 to 2.5 mm, and more preferably 1.5 to 2.5 mm. As a result, it is possible to more reliably prevent the occurrence of the damage starting point at the outer end 7Be of the outer belt ply. The width W1 of the band can be variously set as required, and is not particularly limited. However, when the band is an edge band, it can be set to, for example, 10 to 30% of the maximum belt ply width BW.
[0023]
FIG. 4 shows a reference example .
In this example, the band 9 is composed of a plurality of layers that overlap inside and outside in the tire radial direction. More specifically, the band 9 includes two layers of a first band ply 9A on the inner side in the tire radial direction and a second band ply 9B disposed on the outer side in the tire radial direction. The outer ends 9Ae and 9Be of each of the plurality of band plies are provided on the inner side in the tire axial direction and on the outer side in the tire axial direction of the outer end 7Be of the outer belt ply with respect to the outer end 7Ae of the maximum width belt ply. ing. In this example, the outer ends 9Ae and 9Be of each of the plurality of band plies are both terminated at the same position in the tire axial direction. In such an embodiment, both the band plies 9A and 9B are preferable in that the movement of the maximum width belt ply 7B is further suppressed because a part of the covering portion 21 is formed.
[0024]
5A and 5B show still another embodiment of the present invention.
In this example, the band 9 is the same as the above embodiment in that it is composed of two layers of a first band ply 9A on the inner side in the tire radial direction and a second band ply 9B on the outer side in the tire radial direction. In this example, those in which the positions of the outer ends 9Ae and 9Be in the tire axial direction are different are illustrated. FIG. 5A illustrates an example in which the outer end 9Be of the second band ply 9B is terminated on the inner side in the tire axial direction with respect to the outer end 7Be of the outer belt ply. A partially covered portion 21 is formed. 5B, the outer end 9Ae of the first band ply 9A is terminated on the inner side in the tire axial direction with respect to the outer end 7Be of the outer belt ply, and the second band ply 9B Each of those forming 21 is illustrated.
[0025]
When a band ply having an outer end 9Be or 9Ae that terminates in the tire axial direction from the outer end 7Be of the outer belt ply 7B is provided, the outer end 7Be of each outer end 9Be or 9Ae and the outer end 7Be of the outer belt ply The distance L3 in the tire axial direction is 20 to 90% of the step amount S, more preferably 50 to 90%, and still more preferably 60 to 80%.
[0026]
Although the embodiment of the present invention has been described in detail above, the band 9 includes at least one so-called full band ply 9C having a width extending substantially over the entire belt layer 7, for example, as shown in FIG. the present invention such as may be may be carried out in various aspects.
[0027]
【Example】
Next, more specific examples of the present invention will be described.
A pneumatic radial tire for VAN having a tire size of 195 / 70R15 106 / 104L and the specifications shown in Table 1 was prototyped, and its general durability was tested to compare the performance. As a common specification for tires, the carcass consists of two carcass plies with the polyester cord tilted at 90 ° to the tire equator, and the steel cord on the outside is at an angle of 24 ° with the tire equator and crossing each other. An inclined two-layer belt ply was used. The configuration of the belt layer is as shown in FIG. 1, and the step amount S was set to 6.0 mm. The band was formed of a jointless edge band in which a nylon cord was spirally wound substantially parallel to the tire circumferential direction. The width W1 in the tire axial direction on each side of the edge band was set to 20% of the width BW of the maximum width belt ply.
[0028]
In order to compare the performance, a passenger car of the same size having a single-layer jointless band whose outer end is terminated beyond the outer end of the maximum width belt ply in the tire axial direction as shown in FIG. An experimental tire (conventional example) was also prototyped and tested.
[0029]
In addition, the general durability of the tire is determined by attaching a test tire to a rim (15 × 5 1/2) using a drum testing machine, and running it for 30000 km under the conditions of a load of 12.41 kN and an internal pressure of 600 kPa in the drum testing machine, The damage situation after running was investigated. The results of the test are shown in Table 1. “BEL” means belt ply edge loose, and it is confirmed that the example has improved durability under high load conditions compared to the conventional example. It was done.
[0030]
[Table 1]

[0031]
【The invention's effect】
As described above, the pneumatic tire of the present invention terminates the outer end of the band in the tire axial direction on the inner side in the tire axial direction than the outer end of the maximum width belt ply in the tire axial direction. Even under high-load running conditions, it is possible to prevent the end face of the belt ply at the maximum width from contacting the band and the belt ply at the outer end of the maximum width that has conventionally been caused by such contact. As a result of suppressing rubber peeling, general durability can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a tire (excluding a band) showing an embodiment of the present invention.
FIG. 2 is an enlarged view of the vicinity of the outer end of the belt ply.
FIG. 3 is a schematic diagram thereof;
FIG. 4 is a schematic view near the outer end of a belt ply showing a reference example .
FIGS. 5A and 5B are schematic views of the vicinity of the outer end of a belt ply showing another embodiment of the present invention. FIG. 6 shows the vicinity of the outer end of the belt ply of another embodiment of the present invention. FIG. 7 is a schematic view near the outer end of the belt ply. FIG. 8 is a cross-sectional view of a tread portion showing a conventional band.
FIG. 9 is a schematic diagram thereof [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Belt layer 7A Maximum width belt ply 7B Outer belt ply 7Ae, 7Be Outer end of belt ply 9 Band 9e Outer end of band

Claims (2)

A carcass extending from the tread portion to the bead core of the bead portion through the sidewall portion, a belt layer disposed on the outer side in the tire radial direction of the carcass and inside the tread portion, and an organic fiber on the outer side in the tire radial direction of the belt layer A pneumatic tire comprising a band in which band cords are arranged substantially in the tire circumferential direction,
The belt layer is composed of two belt plies of a belt ply having a maximum width in the tire axial direction and an outer belt ply arranged on the outer side in the tire radial direction of the belt ply of the maximum width. Become
And the outer end in the tire axial direction of the band terminates on the inner side in the tire axial direction than the outer end in the tire axial direction of the maximum width belt ply,
The band extends from the inner side in the tire axial direction of the outer end of the outer belt ply to the outer side of the outer end, so that the maximum band between the outer end of the outer belt ply and the outer end of the maximum width belt ply is obtained. A first band ply comprising a part covering part covering at least a part of the step part of the belt ply of width;
A second band ply that terminates in the tire axial direction from the outer end of the outer belt ply and overlaps the first band ply in the tire radial direction ;
And the tire axial direction distance L1 of the said some coating | coated part is 20 to 90% of step amount S which is the length of the tire axial direction of the said step part, The pneumatic tire characterized by the above-mentioned. The outer belt ply is covered with covering rubber on the inner surface, outer surface, and end surface in the tire axial direction at the end portion in the tire axial direction, so that the distance between the band cord of the band and the end surface is covered. The pneumatic tire according to claim 1 , wherein L2 is 1.0 to 2.5 mm .

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