JP3774541B2 - Pneumatic radial tire - Google Patents

Description

【００３２】
この表１から明らかなように、本発明タイヤ１は、切断破面を有するカーカス材を使用した従来タイヤに比べて荷重耐久性、操縦安定性及び生産性が優れていると共に、従来タイヤと略同等のサイド剛性を維持しながらカーカスコードの使用量を低減することができた。
【００３３】
【発明の効果】
以上説明したように本発明によれば、カーカスコードを左右一対のビードコア間に往復させると共に、該左右のビードコアと各ビードコアに隣接するショルダー部との間のサイド領域にそれぞれ往復させ、これらビードコア間の往復とサイド領域の往復とをタイヤ周方向に連続的に組み合わせながら延在させてカーカス層を形成することで、カーカス層に切断破面を有する従来の空気入りタイヤに比べて耐久性、操縦安定性、生産性を向上しながら、サイド部の剛性を調整自在にし、しかもカーカスコードの使用量を低減してコストダウンを図ることができる。
【図面の簡単な説明】
【図１】本発明の実施形態からなる空気入りタイヤを例示する子午線断面図である。
【図２】図１のタイヤのカーカス層を示す斜視図である。
【図３】図１のタイヤのカーカス層を示す平面図である。
【図４】（ａ）〜（ｅ）は、図１のタイヤにおけるビードロック構造を例示する斜視図である。
【図５】従来タイヤのビードロック構造を示す斜視図である。
【図６】比較タイヤのビードロック構造を示す斜視図である。
【符号の説明】
１ ビード部
２ カーカス層
３ ビードコア
６ カーカスコード
７ ショルダー部
８ サイド領域[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire in which a carcass cord is formed by reciprocating a carcass cord between a pair of left and right bead portions. More specifically, the rigidity of a side portion is improved while improving durability, steering stability, and productivity. The present invention relates to a pneumatic tire that can be adjusted and can reduce cost by reducing the amount of carcass cord used.
[0002]
[Prior art]
Conventionally, when forming a carcass layer to be applied to a general pneumatic radial tire, a belt-like sheet material is obtained by applying a plurality of pre-aligned carcass cords to a calendar process and rubberizing unvulcanized rubber. The rubberized sheet material is cut into a length that is slightly longer than the length of the carcass layer in the longitudinal direction by the winding height at both ends, and one or more of these cut pieces are tired according to the tire size. The carcass material is formed by splicing so as to have a necessary circumferential length in the circumferential direction.
[0003]
The carcass material prepared in this way is transferred to the green tire molding process, wound around a molding drum, then fitted with bead cores at both ends of the outer periphery, and then wrapped around the bead cores at both ends of the carcass material. A green tire is formed by winding and winding side rubber or the like.
[0004]
However, in the carcass layer formed in this manner, a cut fracture surface of the carcass cord is formed at the rolled-up end portion of the carcass material after molding, and this cut fracture surface exists in the tire sidewall portion having a large deformation amount. In many cases, a tire failure is caused by stress concentration on the cut fracture surface. Moreover, in this carcass structure, in order to ensure sufficient rigidity in the circumferential direction of the tire side portion, there is also a problem that a reinforcing layer accompanying an increase in weight must be added as necessary. Furthermore, in order to form such a carcass layer, there are a number of processes such as cutting the sheet material through the calendar process as described above and joining the cut pieces together, which is a factor that reduces productivity. It was.
[0005]
On the other hand, various tires have been proposed in which a carcass structure having no cut fracture surface is formed by continuously knitting a carcass layer from one carcass cord. For example, Japanese Patent Application Laid-Open No. 1-110941 discloses that the carcass structure is formed by sequentially passing a carcass cord between a pair of holding mechanisms arranged in a circle by a reciprocating motion of a rotary arm.
[0006]
However, in the above carcass structure, the carcass cord is knitted by continuously reciprocating between the pair of left and right bead portions, so the rigidity of the side portions cannot be adjusted as necessary, and the degree of freedom in design However, it is practically impossible to reduce the cost by reducing the amount of carcass cord used.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a pneumatic radial tire capable of adjusting the rigidity at the side portion while improving durability, steering stability, and productivity, and reducing the amount of use of the carcass cord to reduce the cost. It is to provide.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a pneumatic tire according to the present invention is a pneumatic radial tire having a carcass layer and a belt layer formed by radially arranging carcass cords, and reciprocating the carcass cord between a pair of left and right bead cores. Each of the left and right bead cores and a shoulder region adjacent to each bead core are reciprocated respectively, and the reciprocation between these bead cores and the reciprocation of the side regions are continuously combined in the tire circumferential direction , and the side regions The carcass layer is formed by extending the reciprocating folded portion from the inner diameter surface of the bead core to 50 mm or more and up to the height of the edge of the belt layer .
[0009]
In this way, the carcass cord is reciprocated between a pair of left and right bead cores, and is also reciprocated to the left and right side regions between the bead core and the shoulder portion, and the reciprocation between these bead cores and the reciprocation of the side regions are continued in the tire circumferential direction. Since the carcass layer does not have a cut fracture surface by extending while being combined in combination, the occurrence of edge separation in the carcass layer can be prevented and the load durability can be improved. In addition, since the carcass cord is arranged so as to extend in the tire circumferential direction at the reciprocating folded portion in the side region, the rigidity in the tire circumferential direction can be increased and the steering stability and the high-speed durability can be improved.
[0010]
In addition, since the carcass layer is formed by continuously reciprocating the carcass cord between the pair of left and right bead cores and the left and right side regions as described above, a complicated and many processes such as a calendar process and a cutting process are performed as in the past. Thus, it is not necessary to form a carcass layer, and the productivity of the tire can be increased.
Furthermore, in the above carcass structure, the carcass cord can be reciprocated in the left and right side regions, and the height of the reciprocating folded portion can be arbitrarily set, so that the rigidity of the side portion can be freely adjusted, In the lower region of the belt layer where the tension is not applied to the carcass cord, the amount of the carcass cord used can be reduced to reduce the cost.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
1 to 3 illustrate a pneumatic tire according to an embodiment of the present invention. In the figure, a carcass layer 2 is mounted between a pair of left and right bead portions 1, 1, and both ends of the carcass layer 2 in the tire width direction are locked to bead cores 3. On the outer side of the carcass layer 2 in the tread portion 4, two belt layers 5 are annularly arranged over the circumference of the tire.
[0012]
As shown in FIGS. 2 and 3, the carcass layer 2 reciprocates one or a plurality of carcass cords 6 between a pair of left and right bead cores 3 and 3 and shoulders adjacent to the left and right bead cores 3 and each bead core 3. It is formed by reciprocating to and from the side region 8 between the portions 7 and extending the reciprocation between the bead cores 3 and 3 and the reciprocation of the side region 8 while continuously combining them in the tire circumferential direction. The reciprocation in the side region is performed by extending the height of the reciprocating folded portion of the side region from the inner surface of the bead core to 50 mm or more and the height of the edge of the belt layer to form a carcass layer. It is important .
[0013]
In the figure, while the carcass cord 6 reciprocates once between the bead cores 3, 3, the left and right side regions 8 reciprocate once. However, the pattern and ratio of this combination are not particularly limited and can be arbitrarily arranged in the tire circumferential direction. In the present invention, if the number of the carcass cords 6 passing through the side region 8 is Z and the number of the carcass cords 6 reciprocating between the bead cores 3 and 3 is B, a range of 0 <B / Z <1, more preferably The carcass layer 2 may be formed in the range of 0.2 <B / Z <0.6.
[0014]
On the other hand, the bead lock structure with respect to the carcass cord 6 is not particularly limited, and can be in various forms as shown in FIGS. That is, in FIG. 4A, the carcass cord 6 reciprocates on the side region 8 outside the bead core 3. In FIG. 4B, the bead core 3 is inserted so that the carcass cord 6 is spirally wound around the bead core 3. In FIG. 4C, the bead core 3 is inserted into one of the pair of loops formed by the carcass cord 6. In FIG. 4D, the carcass cord 6 is sandwiched between two bead cores 3. Further, in FIG. 4 (e), the bead core 3 is sandwiched from inside and outside by a pair of loops formed by the carcass cord 6. In any bead lock structure, the carcass cords 6 do not contact each other.
[0015]
As described above, the carcass layer 2 has a cut fracture surface by forming the carcass layer 2 by continuously combining the reciprocation between the bead cores 3 and 3 of the carcass cord 6 and the reciprocation of the side region 8 in the tire circumferential direction. Therefore, the edge separation in the carcass layer 2 can be prevented and the load durability can be improved. Further, since the carcass cord 6 is arranged so as to extend in the tire circumferential direction in the reciprocating folded portion 9 in the side region 8, the rigidity in the tire circumferential direction can be increased and the steering stability and the high speed durability can be improved.
[0016]
Further, as described above, the carcass cord 6 is continuously reciprocated between the pair of left and right bead cores 3 and 3 and the left and right side regions 8 to form the carcass layer 2. It is not necessary to form a carcass layer through complicated and numerous processes, and tire productivity can be increased. Therefore, in this invention, compared with the pneumatic tire which has a cut fracture surface in a carcass layer, durability, steering stability, and productivity are excellent.
[0017]
Moreover, in the said carcass structure, since the height of the reciprocating folding | turning part 9 in the left and right side area | region 8 can be set arbitrarily, it becomes possible to adjust the rigidity of a side part freely. As a result, it is possible to reduce the amount of use of the carcass cord 6 in the lower region of the belt layer 5 where the tension due to the tire internal pressure is not applied to the carcass cord 6 to reduce the cost.
[0018]
Therefore, as compared with a pneumatic tire knitted by continuously reciprocating the carcass cord between the pair of left and right bead portions, the degree of freedom in design can be increased and the cost can be reduced. In the carcass structure, since at least a part of the carcass cords 6 of all the carcass cords reciprocates between the pair of left and right bead cores 3 and 3, inflation molding can be performed during tire molding.
[0019]
In the present invention, the height H from the inner diameter surface of the bead core 3 of the reciprocating folded portion 9 in the side region 8 may be the same in the tire circumferential direction, or may be varied randomly. Also good. Thus, by varying the height H of the reciprocating folded portion 9, it becomes easy to adjust the rigidity of the side portion, and the degree of freedom in design increases. In addition, it is important that the height H of the reciprocating folded portion 9 from the inner diameter surface of the bead core 3 is 50 mm or more . Thus, the rigidity of a side part is fully securable by making the height H of the reciprocating folding | returning part 9 50 mm or more. The upper limit of the height H of the reciprocating folded portion 9, and until it corresponds to the edge of the belt layer 5.
[0020]
【Example】
The tire 1 of the present invention, the conventional tire, and the comparative tires 1 and 2 were manufactured in which the tire size was 185 / 60R14 and only the carcass structure was changed as follows.
[0021]
Invention tire 1
The carcass cord is reciprocated between a pair of left and right bead cores, and is also reciprocated to the left and right side regions between the bead core and the shoulder portion. The reciprocation between these bead cores and the reciprocation of the left and right side regions is shown in FIG. Thus, the carcass layer was formed by alternately combining at a ratio of 1: 1 in the tire circumferential direction, and the height from the bead core of the reciprocating folded portion in the side region was set to 50 mm.
[0022]
Comparative tire 1
The same carcass structure as the tire 1 of the present invention was used except that the height of the reciprocating folded portion in the side region from the bead core was 20 mm.
[0023]
Conventional tire As shown in FIG. 5, a carcass material having a cut fracture surface of a carcass cord is mounted between a pair of left and right bead portions, and both ends in the tire width direction of the carcass material are arranged around the bead core from the inside of the tire. By winding it outward, the winding height of the carcass cord was 50 mm.
[0024]
Comparative tire 2
As shown in FIG. 6, the carcass cord was continuously reciprocated between a pair of left and right bead portions to form a carcass layer.
[0025]
For these test tires, productivity, side rigidity, steering stability, load durability, and carcass cord usage were evaluated by the following test methods, and the results are shown in Table 1.
[0026]
productivity:
For each test tire, the number of tires produced per unit time was determined and indicated as an index with the conventional tire as 100. The larger the index value, the higher the productivity.
[0027]
Side rigidity:
For each test tire, the rigidity in the tire rotation axis direction was measured and indicated by an index with the conventional tire as 100. The larger the index value, the greater the circumferential rigidity of the side portion.
[0028]
Steering stability:
Each test tire was mounted on a domestic passenger car with an air pressure of 1.9 kg / cm ² and a displacement of 1.6 liters, and a feeling test was conducted by a test driver. The evaluation results are shown as an index with the conventional tire as 100. The larger the index value, the better the steering stability.
[0029]
Load durability:
The load durability was evaluated by a test method based on JIS D4230 and indicated by an index with the conventional tire as 100. The larger the index value, the better the load durability.
[0030]
Carcass cord usage:
About each tire, the usage-amount of the carcass cord was calculated | required and it showed with the index | index which makes the conventional tire 100. The smaller the index value, the smaller the amount of carcass cord used.
[0031]
[Table 1]

[0032]
As apparent from Table 1, the tire 1 of the present invention is superior in load durability, steering stability and productivity to the conventional tire using the carcass material having the cut fracture surface, and is substantially the same as the conventional tire. It was possible to reduce the amount of carcass cords used while maintaining equivalent side rigidity.
[0033]
【The invention's effect】
As described above, according to the present invention, the carcass cord is reciprocated between the pair of left and right bead cores, and is also reciprocated to the side region between the left and right bead cores and the shoulder portion adjacent to each bead core. The carcass layer is formed by extending the reciprocation of the side region and the reciprocation of the side region continuously in the tire circumferential direction to form a carcass layer, which is more durable and steerable than a conventional pneumatic tire having a cut fracture surface in the carcass layer. While improving the stability and productivity, the rigidity of the side portion can be adjusted, and the amount of the carcass cord used can be reduced to reduce the cost.
[Brief description of the drawings]
FIG. 1 is a meridian cross-sectional view illustrating a pneumatic tire according to an embodiment of the invention.
2 is a perspective view showing a carcass layer of the tire of FIG. 1. FIG.
3 is a plan view showing a carcass layer of the tire of FIG. 1. FIG.
FIGS. 4A to 4E are perspective views illustrating a bead lock structure in the tire of FIG. 1;
FIG. 5 is a perspective view showing a bead lock structure of a conventional tire.
FIG. 6 is a perspective view showing a bead lock structure of a comparative tire.
[Explanation of symbols]
1 Bead part 2 Carcass layer 3 Bead core 6 Carcass cord 7 Shoulder part 8 Side region

Claims (3)

In a pneumatic radial tire having a carcass cord and a belt layer formed by radially arranging carcass cords, the carcass cord is reciprocated between a pair of left and right bead cores, and the left and right bead cores and a shoulder portion adjacent to each bead core. The reciprocation between the bead cores and the reciprocation of the side regions are continuously combined in the tire circumferential direction , and the height of the reciprocating folded portion in the side region from the inner diameter surface of the bead core is increased. A pneumatic radial tire in which a carcass layer is formed by extending in a range of 50 mm or more and up to an edge height of the belt layer . The pneumatic radial tire according to claim 1, wherein heights of the reciprocating folded portions in the side regions from the bead core are set to a plurality of different sizes. A carcass layer is formed in a range of 0.2 <B / Z <0.6, where Z is the number of carcass cords passing through the side region, and B is the number of carcass cords reciprocating between the left and right bead cores. The pneumatic radial tire according to claim 1 or 2 .

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