JP4445088B2 - Pneumatic radial tire - Google Patents

Description

【００３９】
【発明の効果】
叙上の如く本発明の空気入りラジアルタイヤは、ベルト補強層に、内側プライに密着する翼状部を形成しているため、ベルト補強層によるタガ効果をその端部に亘って高く発揮でき、ベルト端の動きを強く拘束し、ベルト端からのセパレーションを効果的に抑制しうる。
【図面の簡単な説明】
【図１】本発明の一実施例のタイヤの断面図である。
【図２】ベルト補強層の一部を拡大して示す部分断面図である。
【図３】（Ａ）、（Ｂ）は、ベルト補強層の他の実施例を示す断面図である。
【図４】重荷重用ラジアルタイヤである場合のベルト補強層の一例を示す断面図である。
【図５】従来技術を説明する概略図である。
【符号の説明】
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
６ａ，６ｂ カーカスプライ
７ ベルト層
７ａ〜７ｄ ベルトプライ
９ ベルト補強層
１０ ベルト補強プライ
１０Ａ 本体部
１０Ｂ 折曲がり部
１０Ｃ 翼状部
１１ 内側プライ
２０ 補強コード
２１，２２ プライコード
ＢＥ 端縁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic radial tire that can suppress separation from the belt ply end and improve durability.
[0002]
[Background Art and Problems to be Solved by the Invention]
As shown in FIG. 5, a pneumatic radial tire is widely known in which a belt reinforcing layer b covering at least the outer end portion of the belt layer a is provided outside the belt layer a. This belt reinforcing layer b improves the durability by increasing the restraining force on the belt layer a due to its tagging effect and suppressing the rising of the outer end portion of the belt layer a due to the centrifugal force during high-speed rotation.
[0003]
In recent years, the transition to monofilament cords (single metal cords) has been promoted in recent years because of the advantage of being inexpensive and having high bending stiffness and maintaining the belt stiffness while keeping the amount of steel low. Since such a monofilament cord has a high bending rigidity, the restraint to the belt layer a by the belt reinforcing layer b has become more important for improving the durability.
[0004]
JP-A-1-229704 discloses the structure of a belt reinforcing layer b in a tire using a monofilament cord for the belt layer a, as schematically shown in FIG.
[0005]
This ensures a sufficient inter-cord distance t between the inner belt ply a1 having the maximum width and the extended portion of the belt reinforcing layer b extending beyond the outer end thereof, thereby It has been proposed to suppress separation between the belt plies a1 and a2 and the belt reinforcing layer b.
[0006]
However, in recent years, a structure having a further improved effect of suppressing belt separation is desired in order to meet a stronger demand for improvement in durability.
[0007]
Therefore, the present invention can more effectively suppress the separation from the outer end of the belt ply, based on the fact that the belt reinforcing layer is arranged in close contact with the carcass ply inside the belt reinforcing layer, The object is to provide a pneumatic radial tire that can greatly improve the durability.
[0008]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the invention of claim 1 of the present application is arranged in a carcass made of a carcass ply extending from a tread portion to a bead core of a bead portion through a sidewall portion, inside the tread portion and outside the carcass. A pneumatic radial tire comprising a belt layer composed of at least two belt plies that overlap each other in the radial direction and at least one belt reinforcement ply disposed outside the belt layer. The belt reinforcement ply adjacent outside the outermost belt ply in the radial direction has a bent portion that bends radially inward at the edge of the belt ply on the main body covering the outermost belt ply. through it, along the inner ply is rolled Mashimasu Luke Kasupurai in the tire axial direction outer side than the edge at the inside of the outermost belt ply A wing-shaped portion is provided, and a cord center distance Lt between the reinforcing cord of the wing-shaped portion and the ply cord of the inner ply is between the reinforcing cord of the main body portion and the ply cord of the outermost belt ply. It is characterized by being in the range of 0.5 to 1.5 times the distance Ls between cord centers.
[0009]
According to a second aspect of the present invention, the width of the wing-shaped portion in the tire axial direction is not less than two lengths Lc, which is a length including two reinforcing cords, in the belt reinforcing ply.
[0010]
According to a third aspect of the present invention, the ply cord of the outermost belt ply is a steel monofilament cord.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 illustrates a cross-sectional view when a pneumatic radial tire 1 (hereinafter referred to as a tire 1) of the present invention is a radial tire for a passenger car.
[0012]
In the figure, the tire 1 includes a tread portion 2, sidewall portions 3 extending inward in the tire radial direction from both ends thereof, and bead portions 4 positioned at inner ends of the respective sidewall portions 3.
[0013]
Further, a carcass 6 is bridged between the bead portions 4 and 4 on the tire 1, and a belt layer 7 and a belt reinforcing layer 9 are sequentially formed on the outer side in the radial direction of the carcass 6 and on the inner side of the tread portion 2. It is arranged.
[0014]
The carcass 6 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 6B that is connected to both ends of the bead portion 5 and is folded around the bead core 5. Between the main body portion 6A and the folded portion 6B, a bead apex rubber 8 made of a hard rubber tapering outward from the bead core 5 in the radial direction is arranged and reinforced from the bead portion 4 to the sidewall portion 3. Yes.
[0015]
The carcass 6 is formed of one or more carcass cords arranged at an angle of 75 to 90 ° with respect to the tire circumferential direction, in this example, two carcass plies 6a and 6b. What twisted together several filaments which consist of organic fibers, such as rayon, polyester, and vinylon, can be adopted suitably. A steel cord (multifilament cord) obtained by twisting a plurality of steel filaments may be used as required.
[0016]
Next, the belt layer 7 is formed of at least two belt plies in which belt cords are arranged at an angle of 15 to 70 ° with respect to the tire circumferential direction. In the passenger car tire as in this example, the belt cord is usually formed of two belt plies 7a and 7b arranged at an angle of 15 to 30 °, and the inclination direction of the cord is such that the belt cords intersect each other between the plies. Are placed in a different way.
[0017]
As shown in FIG. 4, a heavy duty radial tire for trucks and buses is usually formed of four belt plies 7a to 7d, and the first inner belt ply 7a in the radial direction has a belt cord of 45 to 45. The second to fourth belt plies 7b to 7d are arranged at an angle of 70 ° and an angle of 15 to 30 °, and the inclination direction of the belt cord is different between the second and third belt plies 7b and 7c. ing.
[0018]
Also, steel cords are generally used as belt cords, but monofilament cords consisting of a single steel filament are inexpensive and have high bending rigidity to keep the belt stiffness low while keeping the belt stiffness low. Can be used more preferably. In the case of a monofilament cord, usually the cord diameter is preferably about 0.25 to 0.70 mm, and the number of cords to be driven is preferably about 25 to 100 per 5 cm. This monofilament cord can be used for all belt plies as in this example, but is preferably used for at least the radially outermost belt ply from the standpoint of excellent fracture resistance.
[0019]
In this example, the two belt plies 7 a and 7 b have substantially the same width, and the belt rigidity is set to be substantially equal over the entire width of the belt layer 7.
[0020]
Next, the belt reinforcing layer 9 includes at least one belt reinforcing ply, in this example, one belt reinforcing ply 10 in which reinforcing cords are arranged at an angle of 0 to 5 ° with respect to the tire circumferential direction.
[0021]
The belt reinforcing ply 10 is preferably formed by spirally winding a narrow belt-shaped ply material in which a plurality of reinforcing cords are arranged in parallel in the tire circumferential direction from the viewpoint of a tag effect. However, it can also be formed by winding a ply material having the same width as the belt reinforcing ply 10 in the tire circumferential direction. As the reinforcing cord, an organic fiber cord such as nylon, rayon, polyester, vinylon or the like can be preferably employed. At this time, the number of cords to be driven is preferably about 30 to 70 per 5 cm.
[0022]
Further, as shown in FIG. 2 in an enlarged manner, the belt reinforcing ply 10 has a main body 10A covering the outermost belt ply 7b, and a bent portion 10B that is bent inward in the radial direction at an edge BE of the belt ply 7b. A wing-like portion 10 </ b> C extending along the inner ply 11 is provided.
[0023]
Here, the inner ply 11, by extending in the tire axial direction outer side than the end edge BE inside said outermost belt ply 7b, means Luke Kasupurai to expose its radially outer surface, The wing-like portion 10C is disposed substantially in close contact with the exposed surface S.
[0024]
In this example, the belt plies 7a and 7b have substantially the same width as described above .
[0025]
The main body portion 10A needs to cover at least the outer end portion of the outermost belt ply 7b. Therefore, as the main body portion 10A, as in this example, a full band shape covering the entire width of the outermost belt ply 7b or a hollow shape with the tire equator removed can be suitably employed.
[0026]
In the present application, in the wing-like portion 10C, the cord center distance Lt between the reinforcement cord 20 of the wing-like portion 10C and the ply cord (corresponding to the carcass cord) 21 of the inner ply 11 is the reinforcement of the main body portion 10A. The cord 20 and the ply cord (corresponding to a belt cord) 22 of the outermost belt ply 7b are regulated to a range of 0.5 to 1.5 times the cord center distance Ls.
[0027]
As a result, the wing-like portion 10C and the inner ply 11 are integrated, and the tagging effect by the belt reinforcing layer 9 is sufficiently exerted over the end portion. As a result, the movement of the belt end can be strongly restrained. Separation from the outer end of the ply can be effectively suppressed. In particular, when the inner ply 11 is the carcass ply 6b as in the present invention, the entire belt layer 7 is surrounded and protected in a shell shape, so that the effect of suppressing the separation is further enhanced.
[0028]
If the distance Lt between the cord centers is less than 0.5 × Ls, the rubber thickness Tt between the cords 20 and 21 becomes too small so that the stress is likely to be concentrated such that the strain is hardly absorbed, and conversely 1.5 × If Ls is exceeded, the restraining force on the belt end is weakened and the movement itself becomes large, so that in any case, the effect of suppressing the separation becomes insufficient. Therefore, the distance Lt between the cord centers is preferably in the range of 0.8 × Ls to 1.2 × Ls.
[0029]
The cord center distance Lt is about 0.8 to 1.4 mm for passenger car tires, about 1.4 to 2.2 mm for heavy duty tires, and the rubber thickness Tt is about 0.5 to 0.7 mm. Is good.
[0030]
In order to sufficiently exhibit the effect of suppressing the separation, the width W1 of the wing-like portion 10C in the tire axial direction is set to a two-length Lc that is a length including two of the reinforcing cords 20 in the belt reinforcing ply 10. The above (W1 ≧ Lc) is preferable. In other words, it is preferable that two or more reinforcing cords 20 exist in the wing-like portion 10C.
[0031]
Next, FIG. 3A shows a reference example , and FIG. 3B shows another embodiment of the present application. The figure illustrates the case where the inner belt ply 7a is wider than the outermost belt ply 7b .
[0032]
In such a case, the wing-like portion 10C is arranged at least on the inner ply 11 closest to the outermost belt ply 7b. FIG. 3A illustrates a case where the wing-like portion 10C is brought into close contact with only the inner ply 11 that is the inner belt ply 7a, and FIG. 3B shows the inner belt ply 7a and the carcass ply. The case where the said wing-like part 10C is closely_contact | adhered to the two inner plies 11 which are 6b is illustrated.
[0033]
As shown in FIGS. 2 and 3B, the structure including the wing-like portion 10C that is in close contact with the carcass ply is preferable because the effect of suppressing the separation is high.
[0034]
Next, FIG. 4 illustrates a case where the tire 1 of the present application is a heavy duty radial tire. In this example, the belt layer 7 is composed of the first to fourth belt plies 7a to 7d as described above, and the third belt ply 7d, the second belt ply 7b, and the carcass ply 6a each have an exposed surface S. The inner ply 11 is configured. In the belt reinforcing layer 9, the wing-like portion 10C is disposed only on the inner ply 11 that is the third belt ply 7d.
[0035]
As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.
[0036]
【Example】
A tire for a passenger car having a tire size of 165 / 70SR13 having the structure shown in FIG. 1 was prototyped based on the specifications in Table 1, and the durability of each sample tire was tested.
The test conditions are as follows.
[0037]
<Durability>
A sample tire was mounted on a passenger vehicle (1600 cc; FF) under a rim (5 J × 13) and internal pressure (220 kPa). After traveling 60,000 km on a general road, the tire was disassembled and generated at the belt end. The crack length was measured and evaluated by an index with Comparative Example 1 taken as 100. The smaller the value, the better the separation resistance and the higher the durability.
[0038]
[Table 1]

[0039]
【The invention's effect】
As described above, the pneumatic radial tire of the present invention has a wing-like portion that is in close contact with the inner ply in the belt reinforcing layer. The movement of the end is strongly restrained, and separation from the belt end can be effectively suppressed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a tire according to an embodiment of the present invention.
FIG. 2 is an enlarged partial sectional view showing a part of a belt reinforcing layer.
FIGS. 3A and 3B are cross-sectional views showing other examples of the belt reinforcing layer. FIGS.
FIG. 4 is a cross-sectional view showing an example of a belt reinforcing layer in the case of a heavy duty radial tire.
FIG. 5 is a schematic diagram for explaining the prior art.
[Explanation of symbols]
2 Tread portion 3 Side wall portion 4 Bead portion 5 Bead core 6 Carcass 6a, 6b Carcass ply 7 Belt layers 7a to 7d Belt ply 9 Belt reinforcing layer 10 Belt reinforcing ply 10A Main body portion 10B Bent portion 10C Wing portion 11 Inner ply 20 Reinforcement Cord 21, 22 Ply cord BE Edge

Claims (3)

A belt composed of a carcass ply that extends from the tread portion through the sidewall portion to the bead core of the bead portion, and at least two belt plies that are arranged inside the tread portion and outside the carcass and overlap each other in the radial direction. A pneumatic radial tire comprising a layer and a belt reinforcing layer comprising at least one belt reinforcing ply disposed outside the belt layer,
The belt reinforcement ply adjacent outside the outermost belt ply in the radial direction is connected to a main body portion covering the outermost belt ply via a bent portion that is bent radially inward at an edge of the belt ply. the provided with a wing portion along the inner ply is rolled Mashimasu Luke Kasupurai axially outwardly than the edge at the inside of the outermost belt ply,
The cord center distance Lt between the reinforcing cord of the wing-like portion and the ply cord of the inner ply is the cord center distance Ls between the reinforcing cord of the main body portion and the ply cord of the outermost belt ply. A pneumatic radial tire characterized by being in a range of 0.5 to 1.5 times. 2. The pneumatic radial tire according to claim 1, wherein the width of the wing-shaped portion in the tire axial direction is equal to or greater than two lengths Lc, which is a length including two reinforcing cords, in the belt reinforcing ply. The pneumatic radial tire according to claim 1, wherein the ply cord of the outermost belt ply is a steel monofilament cord.

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