JPH0655913A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a tread pattern which achieves low pattern noise particularly among the tire noises, and excellent drainage performance. CONSTITUTION:In a pneumatic tire whose tread is divided into multiple land parts 5-9 ranging along the tread circumferential direction by multiple main grooves 1-4 and tread edges T extended along the tread circumferential line and arranged along the tread width direction at certain intervals, sipes 10 extended from its one end to its other end continuously or intermittently in s-shapes are arranged on the tread along the tread circuferential direction at approximately equal intervals and a lot of lug grooves 12-14, which are wider than the sipes, are arranged on the sipes so as to be extended along the direction crossing the sipes and in positions where they at the main grooves 1-4 respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having a tread pattern with low tire noise, especially pattern noise.

[0002]

2. Description of the Related Art Pattern noise is a method of reducing the ratio of grooves occupying the tread ground plane, that is, a so-called negative ratio,
A ribbing technique that makes a block pattern a rib pattern or a shape close to a rib pattern, and a tread pattern that arranges a lateral groove that divides a land portion divided by a plurality of main grooves extending along a tread circumferential line into a plurality of blocks At, by the method of shifting the phase of the lateral groove between land parts,
It can be reduced.

[0003]

Among them, the method of reducing the negative ratio is the most effective, but when the negative ratio is lowered, there is a problem in that the wet performance, especially the drainage capacity is lowered. Similarly, the ribbing method also causes a decrease in wet performance. On the other hand, the method of shifting the phase of the lateral groove is
Although it does not deteriorate other performances required for the tire, it may impair the aesthetic appearance of the tread pattern, and thus has a disadvantage that cannot be applied depending on the tread pattern. Furthermore, pattern noise reduction is not sufficient merely by dispersing the impact at the time of grounding by shifting the phase of the lateral groove.

Therefore, an object of the present invention is to propose a tread pattern which can solve the above problems at once.

[0005]

Means for Solving the Problems The inventors have studied a tread pattern which can satisfy the above-mentioned object. As a result, devising the shape of the groove extending in the direction intersecting with the circumferential groove sacrifices other functions. It has been found that it is advantageous to reduce the pattern noise without fail, and the present invention has been completed. That is, the present invention, the tread of the tire, extending along the tread circumferential line and arranged at intervals in the tread width direction, by a plurality of main grooves and tread ends,
In a pneumatic tire divided into a plurality of land portions that are continuous in the circumferential direction of the tread, in the tread, sipe extending continuously or intermittently from one end to the other end in an S shape is provided at substantially equal intervals in the circumferential direction of the tread. And a lug groove wider than the sipe, extending on the sipe and in a direction intersecting with the sipe, and provided in a large number at each position opening to the main groove.

FIG. 1 shows a main part of a tread of a pneumatic tire according to the present invention. The tread extends along the tread circumferential line, and in this example, main grooves 1 are arranged at substantially equal intervals in the tread width direction. ~ 4 and the tread edge T,
The land portions 5 to 9 extending in the circumferential direction of the tread are divided into one row at the center of the tread and two rows on each side of the tread, for a total of five rows. Further, between the tread ends T, the sipe 10 intermittently extending in an S shape in this example is arranged at substantially equal intervals in the circumferential direction of the tread to divide the land portions 5 to 9 into a large number of sections. Become. Further, a sipe 11 extending in a direction substantially orthogonal to the sipe 10 is added to the land portion 7.

Here, the sipe 12 or the end of the sipe 12 is started, and a lug groove 12 wider than the sipe is provided at a position opening in the main groove, and the lug groove 12 extends in a direction intersecting with the sipe 10 to the main groove. It is important to provide the lug grooves 13 and 14 at the opening positions. All lug grooves must have a length of 1/2 or more of the width of each land.

That is, the lug groove 12 of the illustrated example is on the locus of the sipe 10 of the land portion 7, extends from the sipe 11 toward the main groove 2 or 3 as a starting point, and opens in each main groove. The lug groove 12 has an inclination angle α of 30 to 50 ° with respect to the main groove 2 or 3 on the opening side, and the length 1 of the main groove and its starting end in the tread width direction is 60 to the width of the land portion 7. It is preferable to provide it in the region of 90%.

On the other hand, in the land portions 6 and 8, the lug groove 13 extends in a direction intersecting with the sipe starting from the sipe 10 and opens in the main groove 1, 3 or 2, 4. Also in the lug groove 13, with respect to the main grooves 1, 3 or 2, 4 on the opening side,
It is preferable that the inclination angle β is 60 to 30 ° and the length m in the tread width direction between the main groove and the starting end thereof is 60 to 90% of the width of the land portion 6 or 8.

In the land portions 5 and 9, the lug groove 14 starts in the land portion and extends in a direction intersecting with the sipe 10 and opens in the main groove 1 or 4. Also in the lug groove 14, the inclination angle γ is 50 to 70 ° with respect to the main groove 1 or 4 on the opening side.
It is preferable that the length n in the tread width direction from the main groove to the starting end thereof is 50 to 80% of the width of the land portion 5 or 9.

In particular, in the illustrated example, in the land portions 6, 7 and 8, lug grooves are alternately opened in the main grooves on both sides of each land portion, and further adjacent land portions 6 and 7, or 7 and 8 are provided.
Then, the arrangement is such that the inclination direction of the lug groove is different.

The sipes 10 and 11 have a width that closes when they are in the contact area, specifically, a width of about 0.5 to 1.5 mm, and the lug grooves 12 to 14 have an edge effect and sufficient wetness. It has a width for obtaining the property, specifically, a width of about 2 to 4 mm. Regarding the depth, both the sipe and the lug groove should be slightly shallower than the main groove depth.

FIG. 2 shows another tread pattern according to the present invention. The tread pattern shown in FIG.
In the tread pattern shown in FIG. 3, the sipe 10 is continuously extended between the tread ends T, and the narrow grooves 15 and the main grooves 1 and 4 are spaced apart from each other on the tread end T side.
16 are arranged, and the lug groove 17 opening to these narrow grooves is attached to the land portion 5
And 9 are newly provided.

Here, the other structure of the tire according to the present invention may be in accordance with the conventional practice of tires. For example, a carcass is at least one (up to three) turn-up ply that is wound around the bead core from the inside of the tire to the outside, and the ply is a fiber cord typified by rayon, nylon, and polyester. The belt layer is arranged in a direction substantially perpendicular to the equatorial plane (radial direction), and the belt layer is made of non-stretchable cords such as steel cords and aromatic polyamide fiber cords at 10 to 35 ° with respect to the equatorial plane of the tire. At least two of the belts arranged at an angle of
The formation of at least one auxiliary belt layer having heat-shrinkable cords, represented by nylon cords, arranged substantially parallel to the equatorial plane of the tire over the entire width of the main belt layer with the layers crossing each other. As the main belt layer, a plurality of cords arranged along the circumference of the main belt is spirally wound in a ribbon state. Then, a tread having the above-mentioned tread pattern is arranged on this belt layer.

[0015]

The sipes extending in an S-shape between the ends of the treads are provided at substantially equal intervals in the circumferential direction of the tread to improve the ground contact of the tread and improve the riding comfort without increasing the pattern noise. Moreover, the wet effect is also improved by the edge effect by sipes. The inclination of the sipe with respect to the main groove is preferably about 40 to 70 ° on average.

Further, a plurality of lug grooves extending on the sipe and in a direction intersecting with the sipe and provided at positions respectively opening to the main grooves, that is, the lug grooves are provided between the main grooves on both sides of the land portion. Since they do not penetrate, each land portion becomes a rib which is substantially continuous in the circumferential direction of the tread, and therefore pattern noise can be reduced.

Here, as described above, it is preferable that the lengths 1, m and n in the tread width direction between the main groove of the lug groove and the starting end thereof are preferably 1/2 or more of the tread width. If it is less than the above range, the wet performance is significantly deteriorated. Also, the upper limit is preferably 90% of the tread width, which is
This is because if it exceeds 90%, the continuity in the circumferential direction of the land portion is impaired and the pattern noise increases. Further, the preferred range of the inclination angles α, β and γ of the lug groove is 30 to 70 °, that is, if it is less than 30 °, the land portion surrounded by the lug groove, the sipes and the main groove becomes small and the block rigidity is insufficient. As a result, uneven wear is likely to occur, and if it exceeds 70 °, the acute angle portion of the land portion formed by the intersection of the lug groove and the sipe becomes small, and similarly, uneven wear is likely to occur.

The tread patterns shown in FIGS. 1 and 2 conform to the basic pattern described above, and further, the lug grooves are alternately opened in the main grooves on both sides of each land portion.
Through the lug groove, it is possible to evenly drain water to both main grooves on both sides of the land portion.

[0019]

EXAMPLES Pneumatic radial tires having a tire size of 205/65 R15 (tread width: 140 mm) were prototyped under the following specifications according to the tread patterns shown in FIGS. 1 and 2.

That is, in the test tire A according to the tread pattern of FIG. 1, the main grooves 1 to 4 have a width of 6 mm and a depth of 8 mm, and the sipe 10 has a width of 0.7 mm and a depth of 6.5 mm.
The average inclination angle with respect to the main groove was 55 °. Also,
The lug groove 12 has a width of 2-3 mm, a depth of 6.5 mm, and a length of 17 mm.
And the inclination angle α: 40 °, the width of the lug groove 13 is 2 to 2 similarly.
3 mm, depth: 6.5 mm, length m: 18 mm and inclination angle β:
40-50 °, lug groove 14 width: 2.5-3mm, depth: 6.5mm,
The length n was 14 mm and the inclination angle γ was 60 °.

On the other hand, the test tire B according to the tread pattern of FIG. 2 is the same as the test tire A, except that fine grooves 15 and 16 having a width of 1 mm and a depth of 6.5 mm are provided.
A lug groove 17 similar to the lug groove 14 is newly provided.
In this tread pattern, the lug groove 12 has a width of 2.5 mm, a depth of 6.5 mm, a length of l: 8 mm and an inclination angle α of 40 °,
Similarly, the lug groove 13 has a width of 3 mm, a depth of 6.5 mm, and a length of m: 12.
mm, inclination angle β: 50 °, lug groove 14 width: 3.5 mm, depth: 6.5 mm, length n: 12 mm and inclination angle γ: 60 °.

For comparison, a tire (comparative tire C) having the same size as the tread pattern shown in FIG. 3 was experimentally manufactured. The tread pattern shown in the figure has a pair of narrow grooves 21 arranged on both sides of two central main grooves 20, a pair of main grooves 22 arranged outside thereof, and a pair of narrow grooves arranged outside thereof.
23 are arranged, and narrow lateral grooves 24 and 25 extending in an inclined direction with respect to the main groove are arranged in the tread central area C and both side areas S thereof defined by the narrow grooves 21 and 23. The central main groove 20 and the main groove 22 have a width of 7 mm and a depth of 8 mm, and the fine grooves 21 and 23 have a width of 1.2 mm and a depth of 6.
5mm, lateral grooves 24 and 25, width: 2-3mm and depth: 6.
The arrangement is 5 mm and extends at an inclination angle of 45 to 70 °.

Table 1 shows the results of subjecting these trial tires to a pattern noise test and a hydroplaning test, respectively. The evaluation of each test is represented by an index when each test result of the comparative tire C is 100.

In the pattern noise test, the internal pressure is 1.8k.
After the tires with gf / cm ² were mounted on an ordinary passenger car, the sound inside the vehicle was evaluated when the vehicle was driven by 40 to 100 km / h on a smooth road with two people riding.

In the hydroplaning test, under the same conditions, the tread contact area was measured by taking a photograph of the tread when a straight running was carried out at a water depth of 6 mm at 80 to 90 km / h. The residual ratio of was measured.

[0026]

[Table 1]

[0027]

EFFECTS OF THE INVENTION According to the present invention, a tread pattern having both excellent wet performance and low noise characteristics, which is difficult to achieve by only improving the tread pattern in the past, can be provided. Higher performance can be realized.

[Brief description of drawings]

FIG. 1 is a development view of a tread pattern according to the present invention.

FIG. 2 is a development view of another tread pattern according to the present invention.

FIG. 3 is a development view of a conventional tread pattern.

[Explanation of symbols]

 1 Main groove 2 Main groove 3 Main groove 4 Main groove 5 Land part 6 Land part 7 Land part 8 Land part 9 Land part 10 Sipe 11 Sipe 12 Lug groove 13 Lug groove 14 Lug groove 15 Narrow groove 16 Narrow groove 17 Lug groove

Claims (1)

[Claims] 1. A tread of a tire is divided into a plurality of land portions that extend in the circumferential direction of the tread by a plurality of main grooves and tread ends that extend along the tread circumferential line and are arranged at intervals in the tread width direction. , In pneumatic tires,
Sipe extending continuously or intermittently from one end to the other in an S shape in the tread is arranged at substantially equal intervals in the circumferential direction of the tread, and lug grooves wider than the sipe are provided on the sipe and on the sipe. A pneumatic tire that extends in a direction intersecting with and is provided in large numbers at positions that open in the main groove.