JP2004351993A - Pneumatic radial tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire capable of lightening the tire itself while improving side cutting resistance and maintaining tire performance such as steering stability, etc. <P>SOLUTION: This pneumatic radial tire 1 has a carcass layer 5 folding and engaging a carcass ply cord-aligned at an angle of roughly 90° against the tire peripheral direction from the inside to the outside around a bead core 41 of a pair of left and right bead parts 4 and a belt layer 7 arranged on a tread part 2 on the outside in the diametrical direction of the carcass layer 5, and a side reinforcing layer 9 made of flat woven fabric 10 consisting of warp 11 and weft 12 of organic fiber of fineness of less than 900 decitex is arranged on a side wall part 3 so that the warp 11 and the weft 12 cross with each other at roughly equal angle each other against the tire diametrical direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００３８】
【表２】

【００３９】
表１に示す結果から明らかなように、平織物をサイド補強層に用いた実施例１〜３はいずれもの場合も、従来品の比較例１に比べ耐サイドカット性に優れ、かつサイドウォールゴムを薄肉化し軽量化を実現し、操縦安定性を維持している。
【００４０】
これに対して、サイドウォールゴムを単に薄肉化した比較例２は、軽量化することはできるが耐サイドカット性が悪化し、サイドウォール剛性の低下により操縦安定性も悪化する。経糸と緯糸の打ち込み密度の低い比較例３はサイド補強性が不足し耐カット性が確保できず、また通常のすだれ織をサイド補強層に用いた比較例４は、コードが太く補強層が厚くなりサイドウォールゴムを薄肉化しても軽量化が達成できない。
【００４１】
９４０ｄｔｅｘの太いコードの平織物を用いた比較例５は、補強層が厚くなりサイドウォールゴムを薄肉化しても軽量化が得られず、逆に２２０ｄｔｅｘの細いコードの平織物では軽量化効果は大きいが耐サイドカット性が確保できない。また、平織物の裁断角度が３０度である比較例７は、サイドウォール部の剛性分布がタイヤ周方向で不均等となり操縦安定性が大幅に低下し、乗り心地が悪化することも明らかである。
【００４２】
【発明の効果】
以上説明したように、本発明の空気入りラジアルタイヤによれば、平織物をサイド補強層に用いることで、耐サイドカット性を向上しながらサイドウォールゴムを薄肉化して軽量化を実現し、かつサイドウォール部のタイヤ径方向及び周方向の剛性をバランスさせ操縦安定性や乗り心地などのタイヤ性能を維持する、特に乗用車用に適した空気入りラジアルタイヤを複雑な製造工程を要することなく提供することができる。
【図面の簡単な説明】
【図１】実施形態のタイヤ断面図である。
【図２】実施形態のサイドウォールゴムを一部除去したタイヤ側面図である。
【図３】実施形態の平織物の平面図である。
【図４】従来例のタイヤ断面図である。
【符号の説明】
１……空気入りラジアルタイヤ
２……トレッド部
３……サイドウォール部
４……ビード部
５……カーカス層
６……トレッドゴム
７……ベルト層
９……サイド補強層
１０……平織物
１１……経糸
１２……緯糸[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a pneumatic radial tire suitable for a passenger car that has improved cut resistance of a sidewall portion and reduced tire weight.
[0002]
[Prior art]
In recent years, in response to social demands for lower fuel consumption and higher performance of automobiles, pneumatic radial tires, especially tires for passenger cars, are required to simultaneously reduce tire characteristics and improve tire characteristics such as steering stability.
[0003]
As a technique for reducing the weight of the tire, the thickness of the entire tire is reduced, and in particular, it is generally practiced to reduce the thickness of the rubber gauge on the side portion because it is effective without impairing the performance of other tires.
[0004]
By the way, in order to reinforce the thinned side portion against bending deformation when running on rough roads or over a curb, and to improve durability, a reinforcing layer made of organic fiber cord or steel cord is arranged on the side portion Tires have been proposed (Patent Documents 1 and 2).
[0005]
[Patent Document 1]
JP-A-6-278414
[Patent Document 2]
JP 2001-206026 A
[Problems to be solved by the invention]
However, the pneumatic tire described in Patent Literature 1 uses a fine cord of polyparaphenylene benzobisoxazole (PBO) having high strength and high elasticity for the side reinforcing layer, and has a side cut resistance and a light weight. Although it is possible to achieve both, it is necessary to arrange side protection layers in a substantially sector shape in order to use a rigid and small-stretch PBO cord, so that the number of working steps such as cutting and pasting the protection layer is reduced. Problems such as an increase, a decrease in uniformity due to a gap between the protection layers, or an overlap allowance can be considered.
[0008]
Further, the pneumatic tire described in Patent Document 2 is provided with an annular reinforcing cord layer made of a continuous cord that draws a cycloid curve, and requires a lot of working time to form the reinforcing layer on the side portion. Requires dedicated manufacturing equipment.
[0009]
The present invention has been made in view of the above-described problems, and achieves weight reduction of a tire while improving cut resistance of a sidewall portion, and maintains tire performance such as steering stability, and has a complicated manufacturing process. It is an object of the present invention to provide a pneumatic radial tire that does not require a tire.
[0010]
[Means for Solving the Problems]
The invention according to claim 1 is a carcass layer in which carcass plies arranged at an angle of about 90 ° with respect to a tire circumferential direction are folded back and locked from inside to outside around a bead core of a pair of right and left bead portions, and the carcass layer In the pneumatic radial tire having a belt layer disposed on the tread portion on the radially outer side, a plain woven fabric composed of a warp and a weft of an organic fiber having a fineness of less than 900 dtex, the warp and the weft are arranged in the tire radial direction. The pneumatic radial tire is arranged on the sidewall portion so as to intersect at substantially the same angle with respect to the pneumatic radial tire.
[0011]
According to the pneumatic radial tire of the present invention, a plain woven fabric composed of a warp and a weft of an organic fiber having a fineness of less than 900 dtex is formed at the sidewall portion at an angle substantially equal to each other with respect to the tire radial direction. The side reinforcement layers are arranged so as to intersect with each other, so the side cut resistance is improved, and the rubber thickness of the sidewall can be reduced to 1.5 mm or less at the maximum width of the tire, and the weight of the tire is reduced. In addition, the flat woven fabric of the reinforcing layer is evenly expanded by the pantograph effect even when the sidewall is expanded during tire molding and vulcanization, and tire performance such as steering stability is maintained without impairing uniformity. In addition, since the plain fabric is continuously arranged in the tire circumferential direction, there is no need for a complicated reinforcing layer manufacturing process and equipment.
[0012]
The invention according to claim 2 is the pneumatic radial tire according to claim 1, wherein one of the warp and the weft is a sweet twist cord, and the other is a non-twist cord.
[0013]
In the pneumatic radial tire of the present invention, the cross section of the cord is easily flattened, the thickness of the reinforcing layer is minimized to reduce the weight, and the effect of reducing the weight is improved. Prevention of separation in the layer and making one of the layers a non-twisted cord can contribute to cost reduction.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described.
[0015]
FIG. 1 is a half cross-sectional view of a pneumatic radial tire (hereinafter, referred to as a tire) 1 according to a first embodiment of the present invention. FIG. 2 is a tire in which a side wall rubber is partially removed to show a side reinforcing layer 9. It is a side view.
[0016]
As shown in FIG. 1, a tire 1 is composed of a tread portion 2, a sidewall portion 3 and a bead portion 4, and cords are arranged at an angle of approximately 90 ° with respect to the tire circumferential direction. And a carcass layer 5 composed of a single carcass ply locked with the bead filler 42 interposed therebetween, and two steel plates intersecting each other disposed between the radial outside of the carcass layer 5 and the tread rubber 6. A tread pattern 21 is formed on the outer peripheral portion of the tread portion 1.
[0017]
The carcass layer 5 is composed of a carcass ply in which organic fiber cords such as polyester, nylon, rayon, and aramid are arranged in parallel and woven into a weave and covered with rubber. The belt layer 7 has a small size in the tire circumferential direction. It consists of two steel cord layers stacked so as to intersect at an angle (for example, 10 to 35 °), and tightens the carcass layer 5 to increase the rigidity of the tread portion 2.
[0018]
The side wall portion 3 of the tire 1 has a side extending outside the carcass layer 5 in a range from the vicinity of the locking end portion 5a of the carcass layer 5 at the upper end of the bead portion 4 to the vicinity of the shoulder portion 3b around the tire maximum width portion 3a. The reinforcing layer 9 is arranged continuously in the circumferential direction of the tire 1.
[0019]
As shown in FIG. 3, the side reinforcing layer 9 is formed from a plain woven fabric 10 in which a warp 11 and a weft 12 made of organic fibers having a fineness of less than 900 dtex (hereinafter, dtex is abbreviated as dtex) are woven at right angles. The rubber coated on both sides is used.
[0020]
The reinforcing layer 9 is disposed on the sidewall portion 3 so that the warp yarn 11 and the weft yarn 12 cross each other at substantially the same angle with respect to the radial direction of the tire 1, so that the yarn itself does not sufficiently elongate. The expansion of the reinforcing layer 9 is made uniform in the circumferential direction of the tire by the pantograph effect of the plain woven fabric 10 and also by the expansion of the sidewall portion 3 during tire molding and vulcanization, and the warp 11 and the weft 12 are formed in the tire radial direction. Can be deformed into a bias shape having a uniform distribution on the left and right.
[0021]
As a result, the side cut resistance is improved, the unevenness of the surface of the sidewall portion 3 is not reduced, and the uniformity is not impaired, and the rigidity balance in the tire circumferential direction and the radial direction can be maintained. Even if the thickness of the side wall rubber is reduced to 1.5 mm or less, tire performance such as steering stability and riding comfort can be maintained.
[0022]
Further, the plain woven fabric 10 can be easily prepared as a base material of the side reinforcing layer 9 because of its excellent weaving property, and the rubber coated cloth cut at a predetermined width at 45 degrees to the cord direction is used. The side reinforcing layer 9 can be formed by affixing to the sidewall portion 3 at the time of tire molding, and there is an advantage that a complicated manufacturing process of the reinforcing layer and a special manufacturing device are not required and the tire manufacturing process is not changed. is there.
[0023]
Examples of the organic fibers constituting the warp yarn 11 and the weft yarn 12 include nylon fibers such as nylon 6,66, polyester fibers such as polyethylene terephthalate, vinylon, and aramid fibers. Among them, nylon 66 has high strength and high resistance. It is easy to secure the side cut property, and since it has a high melting point, it can withstand high-temperature vulcanization even in a thin-walled side wall part, and has a moderate elongation during vulcanization to adhere the tire to the vulcanization mold. This is preferable because it does not cause molding failure and is advantageous in cost.
[0024]
The warp yarns 11 and the weft yarns 12 are multifilament yarns made of the above organic fibers, and the number of filaments is not particularly limited, but is preferably 5 to 50 filaments, and more preferably 10 to 30 filaments. This is because if the number of filaments is small, the yarn is difficult to be thick and flat and the reinforcing layer 9 is thick, and if the number of filaments is large, filament breakage is likely to occur.
[0025]
The thickness of the warp yarn 11 and the weft yarn 12 is preferably less than 900 dtex, and when it is more than 900 dtex, the plain woven fabric 10 becomes thicker, the thickness of the side reinforcing layer 9 increases, the amount of rubber used is increased, and weight reduction is realized. If it is too thin, on the other hand, the strength and rigidity of the cord will be low, and it will not be possible to secure the side reinforcement. Therefore, a cord with a thickness of about 300 dtex or more is preferred. And the adhesiveness is reduced.
[0026]
One of the warp 11 and the weft 12 of the plain woven fabric 10 is preferably twisted about 5 to 20 times per 10 cm. This twist makes it easier to form a gap between the warp or the weft, improves the adhesion of the plain woven fabric 10 due to the anchoring effect due to the intrusion of rubber, and can prevent the separation at the sidewall portion 3 that undergoes bending deformation. . Of course, a sweet twisted cord can be used for both the warp 11 and the weft 12. However, since the prevention of the separation can be achieved only by using one of the sweet twisted cords, the other may be a non-twisted cord.
[0027]
Further, by using the sweet twisted and non-twisted cords for the warp 11 and the weft 12, the cords coated with rubber are flattened, and the reinforcing layer 9 can be made thinner, and the effect of reducing the weight of the tire is improved. On the other hand, if a cord having a normal number of twists is used for the warp 11 or the weft 12, the cord becomes thicker, it is hard to be flattened, the reinforcing layer 9 cannot be made thinner, and it is against weight reduction. When non-twisted cords are used, all of the filaments come into close contact with each other, so that rubber cannot enter between the cords and the adhesiveness is reduced.
[0028]
Here, the driving density of the warp yarn 11 and the weft yarn 12 of the plain fabric 10 is about 30 to 50 yarns / 50 mm, more preferably about 30 to 50 yarns / 50 mm, from the viewpoint of appropriately maintaining the rigidity of the sidewall portion 3 related to steering stability and riding comfort. A desirable range is about 35 to 50 wires / 50 mm, and it is necessary to design in consideration of the relationship with the thickness of the cord. In addition, it is preferable that the thickness and the driving density of the warp yarn 11 and the weft yarn 12 have the same thickness and density in order to effectively exert the pantograph effect at the time of expansion.
[0029]
(Example)
Hereinafter, the present invention will be described in more detail with reference to examples.
[0030]
According to the specifications shown in Tables 1 and 2, 14 filaments of nylon 66 and 440 dtex multifilament yarn (Comparative Example 5 uses 30 filaments, 940 dtex, Comparative Example 6 uses 7 filaments, 220 dtex) warp A plain woven fabric in which wefts are orthogonally woven or a cord made of nylon 66, 940 dtex / 2 woven in a blind weave is applied to the side reinforcing layer, and each example having the tire structure shown in FIG. An example pneumatic radial tire was prototyped. The following evaluation was performed, and the results are shown in Tables 1 and 2.
[0031]
The size of the prototype tire is 175 / 70R1382S, the carcass layer is 1 ply of polyester 1670 dtex / 2 (implantation density 45 pcs / 50 mm), and the belt layer is the steel cord 2 + 2 × 0.25 (implantation density 38/50 mm) at an intersection angle 23. It has a two-layer structure. FIG. 4 is a half cross-sectional view of a comparative example 1 tire of a conventional product having no side reinforcing layer and a thick side wall rubber as before (the rubber thickness outside the carcass layer is 2.5 mm).
[0032]
The side reinforcing layer is a belt-shaped reinforcing layer cut to a predetermined width at an angle of 45 or 30 degrees with respect to the warp of the plain woven fabric coated with rubber, or a predetermined angle at an angle of 30 degrees with respect to the warp of the blind woven fabric coated with rubber. The band-shaped reinforcing layer cut into a width is stuck on the carcass of the side wall portion in the circumferential direction of the tire by the first molding and expanded, and the side wall rubber, the belt layer and the tread rubber are stuck by the second molding to produce an unvulcanized tire. The tire was manufactured through a conventional vulcanization process. A 45-degree cut plain woven fabric is pantograph-deformed by expansion and warps and wefts are deformed in a biased manner with a uniform distribution of the warp and weft in the tire radial direction. It was even.
[0033]
The cord density at the time of tire is the cord density near the tire maximum width (average value of warp and weft for plain woven fabric) (book / 50 mm), and the thickness of the sidewall rubber is the thickness of the reinforcing layer or carcass layer near the tire maximum width. This is the rubber thickness of the thinnest part of the outer sidewall rubber.
[0034]
(Evaluation method)
Tire weight: The average value of the weight of the prototype tire. It is indicated by an index with Comparative Example 1 being 100, and the smaller the numerical value, the lighter the weight.
[0035]
Side cut resistance (plunger test): Each test tire was mounted on a standard rim at an air pressure of 190 KPa, and a steel rod having a diameter of 32 mm, a hemispherical tip, and a weight of 30 kg was perpendicular to the sidewall portion of the tire maximum width. After dropping from a height of 300 mm, the number of broken cords in the side wall portion was measured. The smaller the number of broken cords, the better.
[0036]
Driving stability: Assemble each test tire on a standard rim, attach it to a passenger car at an air pressure of 190 KPa, and use three test drivers to test driving stability such as straight running, lane change, and handling on asphalt dry road surfaces. Evaluation was made out of 10 points by feeling. The lane change running stability test method was based on JASO C-707, and the handling was based on JASO C-708. The higher the score, the better.
[0037]
[Table 1]

[0038]
[Table 2]

[0039]
As is evident from the results shown in Table 1, in each of Examples 1 to 3 using plain woven fabric for the side reinforcing layer, the side cut rubber was more excellent than the comparative example 1 of the conventional product, and the side wall rubber was used. The thinner and lighter, the steering stability has been maintained.
[0040]
On the other hand, in Comparative Example 2 in which the sidewall rubber is simply made thinner, the weight can be reduced, but the side cut resistance deteriorates, and the steering stability also deteriorates due to the decrease in the sidewall rigidity. In Comparative Example 3 in which the warp and weft driving densities were low, the side reinforcing properties were insufficient and cut resistance could not be ensured. In Comparative Example 4 in which ordinary blind cloth was used for the side reinforcing layer, the cord was thick and the reinforcing layer was thick. Even if the thickness of the side wall rubber is reduced, weight reduction cannot be achieved.
[0041]
In Comparative Example 5 using a 940 dtex thick cord plain weave, weight reduction was not obtained even when the reinforcing layer was thickened and the side wall rubber was made thinner. Conversely, a 220 dtex thin cord plain weave had a large weight reduction effect. However, the side cut resistance cannot be secured. In Comparative Example 7 in which the cutting angle of the plain fabric is 30 degrees, it is also clear that the rigidity distribution of the sidewall portion is uneven in the tire circumferential direction, the steering stability is significantly reduced, and the riding comfort is deteriorated. .
[0042]
【The invention's effect】
As described above, according to the pneumatic radial tire of the present invention, by using a plain fabric for the side reinforcing layer, the side wall rubber is thinned while the side cut resistance is improved, and the weight is reduced, and Provide pneumatic radial tires suitable for passenger cars, especially without complicated manufacturing processes, that maintain tire performance such as steering stability and ride comfort by balancing the tire radial and circumferential rigidity of the sidewall portion. be able to.
[Brief description of the drawings]
FIG. 1 is a sectional view of a tire according to an embodiment.
FIG. 2 is a side view of the tire with a part of a sidewall rubber removed from the embodiment.
FIG. 3 is a plan view of the plain fabric of the embodiment.
FIG. 4 is a sectional view of a conventional tire.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Pneumatic radial tire 2 ... Tread part 3 ... Side wall part 4 ... Bead part 5 ... Carcass layer 6 ... Tread rubber 7 ... Belt layer 9 ... Side reinforcement layer 10 ... Plain fabric 11 ... warp 12 ... weft

Claims (2)

A carcass layer in which carcass plies arranged at an angle of about 90 ° with respect to the tire circumferential direction are folded back and locked from inside to outside around a bead core of a pair of right and left bead portions, and the tread radially outside the carcass layer. In a pneumatic radial tire having a belt layer arranged in the part,
Plain woven fabric consisting of warps and wefts of organic fibers with a fineness of less than 900 dtex,
A pneumatic radial tire, wherein the warp and the weft are arranged on the sidewall portion so as to intersect at substantially the same angle with respect to the tire radial direction. The pneumatic radial tire according to claim 1, wherein one of the warp and the weft is a sweet twist cord, and the other is a non-twist cord.

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