JP5116191B2 - Pneumatic tire - Google Patents

Description

【００２５】
上記表１で明らかなように、Ｗ≧０．４・１／２ＴＷで、Ｗ１＞Ｗ３＞Ｗ２とすることによって、従来例Ａおよび比較例Ｂ〜Ｄのゲーピング指数が１００〜６９であるのに対し、本発明の実施例Ｅ、Ｆはいずれもゲーピング指数が低い値（数）となって、ゲーピングの力が低くなり、顕著な作用効果を奏することが理解できる。
【００２６】
【発明の効果】
以上詳述したように本発明によれば、ゲーピング量およびショルダー摩耗／レール摩耗を著しく改善したリブパターンのトレッド有する空気入りタイヤを提供でき、特に限定するものではないが重荷重用の操舵輪として有益である。
【図面の簡単な説明】
【図１】 空気入りタイヤのトレッドを示す平面図（展開図）である。
【図２】 空気入りタイヤのトレッド要部の断面図である。
【図３】 空気入りタイヤのトレッド要部の断面図である。
【図４】 従来例のトレッド平面図である。
【符号の説明】
１ センターリブ
３Ｌ、３Ｒ 左右のショルダーリブ
５Ｌ、５Ｒ 左右のショルダー主溝
８ カーカス
９ ベルト層
１０Ｌ、１０Ｒ ゴム緩和層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire, and more specifically to a pneumatic tire having a radial structure suitable for heavy loads such as trucks and buses.
[0002]
[Prior art]
A pneumatic tire, particularly a pneumatic tire having a radial structure, is formed in a toroidal shape by a tread portion, a shoulder portion, a sidewall portion, and a bead portion, and a radial structure carcass is disposed from the left and right bead portions to the tread, and the tread portion. A belt that restricts the radial expansion of the carcass is embedded in the outer periphery of the carcass.
[0003]
Pneumatic tires used as front wheels (steering wheels) of vehicles (referred to as trucks, buses, etc.) are placed in the center of the tread due to the effects of “lateral force accompanying steering” and “alignment of the wheels themselves (front wheel alignment)”. On the other hand, a phenomenon (called shoulder wear) occurs in which the wear rate (wear degree) of the left and right shoulders becomes significantly faster, which makes it impossible for the wearer to exhibit sufficient wear performance, and the tire must be rotated with the drive wheels. It is disadvantageous.
[0004]
On the other hand, the tread pattern of this front wheel (also with rear wheel steering) is mainly a “rib”, “mix”, “rib / lag” pattern, and since all are steered wheels, grooves (vertical grooves or It is a tread design with a main groove).
Since these tread patterns have deep and wide main grooves in the circumferential direction, the grooves (when the tire internal pressure is applied) during inflation (the parts with weak tread rigidity with respect to land parts such as ribs) Therefore, a force that tends to be rounded at the tire shoulder portion (so-called gapping force) is generated, and the radius of the tread portion is uneven (the radius of the left and right shoulder portions is smaller than that of the center portion).
[0005]
This non-uniformity causes unevenness of the movement of the land part when touching the road surface and when it is not touching (away from the road surface) (the center part is difficult to move and the shoulder part is easy to move). This was one of the causes of premature wear of the left and right shoulders.
In addition, when the tire rotates and changes from a non-grounding state to a grounding state, the shape of the groove greatly changes from the gating state (the groove width becomes narrow), so that the gating is adjacent to the groove where the gating occurs. The land edge has a large movement when it touches down, the edge wears quickly, and the edge becomes round and wears. Eventually, uneven wear starting from the edge (generally called river wear / rail wear) I was waking up.
[0006]
[Problems to be solved by the invention]
In order to improve the above-mentioned problem, there is a technique shown in FIG.
This is because the tread portion T is formed into a rib pattern with the center rib 1 and the left and right side ribs 2L and 2R and the left and right shoulder ribs 3L and 3R in the main grooves 4L, 4R, 5L and 5R in the circumferential direction. The sipe 6L, 6R having a constant width is formed at a rib edge adjacent to the grooves 5L, 5R at a circumferential interval, and the sipe 7L, 7R crossing the rib (land) is formed at a circumferential interval. Thus, by reducing the rigidity of the entire rib or the rib edge, the movement of the entire rib or the rib edge due to the ground contact is received to reduce the “rubbing” with the road surface.
[0007]
According to the conventional example shown in FIG. 4, although the occurrence of shoulder wear / rail wear can be delayed, after the middle wear, the rigidity of the land (rib) is increased by the decrease in tread rubber (rib rubber amount) due to wear. However, there is a problem that it does not last long, and there is a lack of rubber from the sipe 6L, 6R, 7L, 7R or rail wear starting from the sipe, and the current situation is that it has not been improved sufficiently.
[0008]
Further, as another means, attempts have been made to improve by multiradius in a deflated state when new.
That is, the present applicant has proposed an improvement (Japanese Patent Application No. 2000-152044, but not a publicly known technology) that uses a multi-tread radius during deflation and a uniform radius during inflation.
[0009]
Specifically, in a pneumatic tire in which a carcass is disposed across a tread portion, a shoulder portion, and a sidewall portion, and a belt is provided on the outer periphery side of the carcass in the tread portion, the shoulder portion before air filling A pneumatic tire is characterized in that the relationship between the radius of curvature of the carcass is R1 and the radius of curvature of the carcass after air filling is R2, and the relationship between the two is set to R1 ≦ R2. ”
[0010]
Although this proposed technology is useful as it is, it is effective in the conditions where tire rotation speed, tire internal pressure, heavy load, etc. change every moment because multiradius is set after affirming gating. It was not possible.
As a result of diligent research, the present inventor firstly devised the rib pattern, in particular, the shoulder main groove and / or the shoulder rib, in the pneumatic tire having the tread of the rib pattern. The company has succeeded in developing a pneumatic tire that can significantly improve rail wear.
[0011]
Secondly, a pneumatic tire in which the amount of gapping is reduced is successfully developed by reflecting the belt layer (belt rigidity) in the main groove.
[0012]
[Means for Solving the Problems]
A pneumatic tire according to the present invention has a tread having a rib pattern including a center rib, a side rib, and a shoulder rib, which are partitioned by a main groove extending in the circumferential direction and are arranged from the center in the width direction toward the outside on both sides in the width direction. W1 when the total width of the tread is TW and the tread width from the outer edge of the tread to the center of the groove width of the shoulder main groove, which is a groove that divides the side rib and the shoulder rib, is W1. ≧ 0.4 · 1 / 2TW, and a plurality of belt layers made of cords inclined at a constant angle with respect to the circumferential direction are overlapped with the cords and embedded in the inner tread rubber of the rib pattern. And by the plurality of belt layers, the distance in the radial direction compared to the inner overlapped portion at the outer end portion in the width direction. Large rubber relaxation layer is formed, the outermost belt layer has the same inclination direction of the belt layer and the cord on the outside of the belt layer of the most the radial direction of the plurality of belt layers superimposed is provided the side rib and the distance a tread width of the shoulder rib from the groove width center of the shoulder main groove which divides up the tread outer edge W1, from the tread outer edge to the inner edge in the width direction of the rubber relieving layer Is the tread width W2 , and the distance from the outer edge of the tread to the edge of the outermost belt layer in the width direction is the tread width W3, W1>W3> W2 .
[0013]
The Rukoto to the W 1> W3> W2, the belt increasing the belt rigidity of the right and left shoulder main groove gradually decreases is allowed while Gepingu toward the direction of right and left shoulder portions stiffness (the belt layers) are generated, and the center section Ru can be made uniform.
In the pneumatic tire described above, it is desirable that the cord constituting the belt layer is a steel cord that is aligned and juxtaposed and covered with rubber (topping). A code can also be adopted.
[0014]
The cross-sectional shape of the rubber relaxation layer is arbitrary, but desirably it is a wedge-shaped cross section or a triangular shape, and it is recommended that the rubber gauge layer is interposed with the thinner gauge thickness facing inward.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, a common code | symbol is used for the part which is common in the structure already described with reference to FIG.
FIG. 1 is a plan view showing a tread of a pneumatic tire. A tread portion T is a rib pattern including a center rib 1, left and right side ribs 2L and 2R, and left and right shoulder ribs 3L and 3R. It is isolated by the grooves 4L, 4R, 5L, 5R.
[0016]
When the total width of the tread (tread portion) T is TW and the tread width from the outer edge of the tread to the center of the groove width of the shoulder main groove 5L is W1, W1 ≧ 0.4 · 1 / 2TW. Although FIG. 1 shows the left shoulder main groove 5L, the same applies to the right shoulder main groove 5R (hereinafter the same).
Thus, by setting W1 ≧ 0.4 · 1 / 2TW, each of the left and right shoulder main grooves 5L and 5R is brought close to the tread center portion, and the influence of the force that the tire tends to be rounded during inflation is small. (To reduce the power of gapping).
[0017]
Furthermore, by increasing the rib width of the left and right shoulder ribs 3L and 3R with respect to other rib widths, specifically by increasing the width by 1.2 to 2.0 times, the rigidity of the left and right shoulder portions of the tire is improved. This is advantageous for shoulder wear.
Therefore, the number of sipes 6L and 6R processed at the edges of the left and right side ribs 2L and 2R and the shoulder ribs 3L and 3R can be reduced, and the occurrence of shoulder wear / rail wear is caused by wear of the rubber (rib) of the tread T. Is also improved from the new article to the second half of wear (including the middle period).
[0018]
2 and 3 show cross-sectional views of the main part of the tread of the pneumatic tire. Of course, the rib pattern satisfying W1 ≧ 0.4 · 1 / 2TW described above can also be used in FIGS. 2 and 3. It is.
2 and 3, the main part on the left side from the center OO of the tire is shown in cross section, but the cross section of the main part on the right side is the same.
[0019]
2 and 3, a plurality of belt layers (also referred to as breaker layers) 9 are disposed on the crown portion (tread portion) of the carcass 8 having a radial structure, and the belt layer 9 is embedded in the tread rubber. ing.
The belt layer 9 is obtained by coating (topping) rubber on a cord (a steel cord is a fiber cord or the like, regardless of the material) that is aligned with a certain angle with respect to the circumferential direction. When a plurality of belt layers 9 are overlapped, the cords are provided with different inclination directions (therefore, the upper and lower belt layers intersect with each other), and the belt layers 9 have left and right overlapping portions. Rubber relaxation layers 10L and 10R are interposed between both end portions 9L and 9R (in the figure, between the left end portions 9L but the same applies to the right side 9R).
[0020]
The left and right end portions 9L, 9R and the rubber relaxation layers 10L, 10R of the overlapping portion in the belt layer 9 are positioned in the shoulder ribs 3L, 3R on the outer side of the shoulder main grooves 5L, 5R. The belt rigidity is reflected in the shoulder main grooves 5L and 5R to reduce the amount of gapping.
Specifically, when the tread width from the tread edge to the center of the groove width of the shoulder main grooves 5L and 5R is W1, and the tread width from the tread outer edge to the inner edges of the rubber relaxation layers 10L and 10R is W2. As shown in FIGS. 2 and 3, W1> W2.
[0021]
Further, in FIG. 3, an outermost belt layer 9A having the same inclination direction of the cord is provided on the belt layer 9, and left and right end edges 9A-L and 9A-R shoulder main grooves of the outermost belt layer 9A. It is set between 5L, 5R and the inner end edges 10L-A, 10R-A of the rubber relaxation layers 10L, 10R.
Specifically, when the tread width from the outer edge of the tread to the left and right edges 9A-L, 9A-R of the outermost belt layer 9A is W3, W1>W3> W2.
[0022]
As a result, the overall range of restraint of the belt stiffness can be expanded, and the belt stiffness of the shoulder main grooves 5L and 5R where the gapping occurs can be made high and uniform with the center portion while gradually reducing the belt stiffness in the shoulder direction. It is.
Further, the rubber relaxation layers 10L and 10R shown in FIG. 2 and FIG. 3 intervene because when belts of different angles (different cord angles) are overlapped, the belt edges are distorted, resulting in tire failure. Although it is (inserted), its cross-sectional shape is arbitrary. However, as shown in the drawing, it is desirable to interpose the one having a wedge shape or a triangular shape and having a thinner gauge thickness (inner end edges 10L-A, 10R-A side) inward.
[0023]
The number of belt layers 9 to be stacked is 2 to 4, but FIG. 2 shows 3 sheets and FIG. 3 shows 4 sheets. However, the number of sheets is arbitrary. In addition, when the relaxation layers 10L and 10R are interposed, it is desirable to extend the lower layer (inner diameter side) belt layer outwardly and receive the relaxation layers 10L and 10R at the extended portion.
The inventor of the present invention used a pneumatic radial tire of tire type 11R22.5 (however, a hand-carved product) for conventional example A and comparative examples B to D and examples E and F of the present invention, and the amount of gapping (measured at JATMA internal pressure). Is shown in Table 1 below.
[0024]
[Table 1]

[0025]
As is clear from Table 1, in W ≧ 0.4 · 1 / 2TW, by the W1>W3> W2, though Gepingu index of the conventional example A and comparative example B to D is from 100 to 69 On the other hand, it can be understood that Examples E 1 and F 2 of the present invention both have a low value (number) of the Gaping index, the Gaping power is reduced, and there are significant effects.
[0026]
【Effect of the invention】
As described above in detail, according to the present invention, it is possible to provide a pneumatic tire having a tread having a rib pattern in which the amount of gapping and shoulder wear / rail wear are remarkably improved, and it is useful as a steered wheel for heavy loads, although not particularly limited thereto. It is.
[Brief description of the drawings]
FIG. 1 is a plan view (development view) showing a tread of a pneumatic tire.
FIG. 2 is a cross-sectional view of a main part of a tread of a pneumatic tire.
FIG. 3 is a cross-sectional view of a main part of a tread of a pneumatic tire.
FIG. 4 is a plan view of a conventional tread.
[Explanation of symbols]
1 Center rib 3L, 3R Left and right shoulder ribs 5L, 5R Left and right shoulder main grooves
8 Carcass
9 Belt layer 10L, 10R Rubber relaxation layer

Claims (2)

A pneumatic tire having a tread of a rib pattern composed of a center rib, a side rib and a shoulder rib, which is partitioned by a main groove extending in the circumferential direction and arranged from the center in the width direction toward the outside on both sides in the width direction,
When the total width of the tread is TW, and the width of the tread from the outer edge of the tread to the center of the width of the shoulder main groove, which is a groove separating the side rib and the shoulder rib, is W1, W1 ≧ 0.4 · 1 / 2TW,
A plurality of belt layers made of cords inclined at a constant angle with respect to the circumferential direction are overlapped with each other so as to cross the cords, and are embedded in an inner tread rubber of the rib pattern,
By the plurality of belt layers, a rubber relaxation layer having a large interval in the radial direction is formed at the outer end portion in the width direction as compared with the inner overlapping portion.
An outermost belt layer having the same inclination direction of the belt layer and the cord is provided on the outermost belt layer in the radial direction in the plurality of the belt layers stacked,
The distance from the groove width center of the shoulder main groove that divides the side rib and the shoulder rib to the outer edge of the tread is a tread width W1, and the distance from the outer edge of the tread to the inner edge of the rubber relaxation layer in the width direction W1>W3> W2 when the distance is a tread width W2 and the distance from the outer edge of the tread to the edge of the outermost belt layer in the width direction is a tread width W3. Pneumatic tire. The rubber relaxation layer has a wedge shape or a triangular shape in cross section including the rotation axis,
The pneumatic tire according to claim 1, wherein the gauge tire is interposed with the thinner gauge side facing inward .

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