JP4266600B2 - Tire with asymmetric tread pattern - Google Patents

Description

【００３３】
【発明の効果】
この発明によれば、従来は背反の関係にあった、耐ハイドロプレーニング性と操縦安定性及び耐摩耗性能とを、高次元で両立した、タイヤを提供することができる。
【図面の簡単な説明】
【図１】 この発明に従うトレッドパターンを示す図である。
【図２】 細溝の構造を示す図である。
【図３】 この発明に従う別のトレッドパターンを示す図である。
【図４】 比較のトレッドパターンを示す図である。
【符号の説明】
１ａ，１ｂ，１ｃ，１ｄ 周方向溝
２ａ，２ｂ 陸部列
３ａ，３ｂ 陸部
４ リブ状陸部
５ａ，５ｂ 傾斜溝
６ 細溝
７ ディンプル[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tire suitable for use in a passenger car, and more particularly to a high motion performance tire that maintains high hydroplaning performance on wet road surfaces while ensuring vehicle stability and wear resistance performance on dry road surfaces. It is.
[0002]
[Prior art]
In radial tires, increasing the strength of the tread and the belt inside the tread is effective for improving the high-speed running performance. In order to have the same, it becomes necessary to improve the drainage performance in the tread portion that is widened with flattening. In this case, in order to improve the so-called hydroplaning performance, the contact ratio of the tread land part is lowered, or a wide circumferential groove is formed in the center of the tread part in the width direction so as to follow the direction of water flow (streamline) during drainage. In the shoulder portion, an inclined groove extending in an oblique direction with respect to the equator of the tire is provided in accordance with an oblique streamline, thereby increasing drainage efficiency.
[0003]
On the other hand, in order to utilize the high belt tension and high rigidity at the center due to the so-called saddle effect, in order to express grip strength and steering stability when traveling at high speed on dry road surfaces, etc. The tread pattern of the rib base tone which does not provide a groove or the like in the tread center portion is adopted.
[0004]
Accordingly, the current situation is that the drainage performance on the wet road surface and the grip force and the steering stability when traveling on the dry road surface at high speeds are inevitably contradicted. In addition, since the tread center portion has high belt rigidity as described above, the circumferential distortion of the tread center portion accompanying rotation becomes excessive, and the center portion is preferentially worn, so-called center wear is likely to occur. There is also the problem of becoming.
[0005]
In view of such a situation, a tread pattern is currently being designed as a place where the above-mentioned various required performances can be realistically compromised. However, a result satisfying much could not be obtained.
[0006]
[Problems to be solved by the invention]
The present invention has been made with the object of solving the above-mentioned problems of the prior art, and has been developed in a high-dimensional manner with hydroplaning resistance, steering stability and wear resistance performance, which have been in a trade-off relationship in the past. The purpose is to propose a method to achieve both.
[0007]
[Means for Solving the Problems]
The inventors pay attention to the situation in which the tire is mounted on an actual vehicle and used, particularly the tire mounting posture (camber angle, toe-in, etc.), the ground contact shape at that time, and the flow of drainage and water (streamlines). As a result of detailed analysis of these, the following findings (a) to (d) were obtained.
(A) In most vehicles, tires are mounted under a slight toe-in or negative camber,
(B) As a result, a long grounding portion moves from the tire equator to the inside of the vehicle at the time of wearing. Therefore, in order to improve steering stability, the tread center portion (maximum belt tension) is considered from the viewpoint of grounding area and belt rigidity. Part) and the tread ground contact circumference maximum part, a large pattern in the tire width direction rigidity is required,
(C) On the other hand, since the belt rigidity is high at the tread center portion, in the land portion where the rigidity in the tire width direction is high, the circumferential distortion caused by the rotation of the tire is large, and the distortion is released when kicking. The wear increases due to the occurrence of this. In order to avoid such a phenomenon, it is necessary to achieve both tire width rigidity and circumferential rubber escape.
(D) The contribution of the circumferential groove to hydroplaning resistance, that is, drainage, is maximized at the maximum portion of the tread circumferential contact length. Therefore, in order to achieve both hydroplaning resistance and improved steering stability, the land position and the circumferential groove position are shifted from the relationship with (a) above, and the inside of the vehicle when the vehicle is mounted on the tire equatorial plane. It is effective to widen the circumferential groove of
And led to the present invention.
[0008]
The gist configuration of the present invention is as follows.
(1) A tire having an asymmetric tread pattern in which a direction with respect to the inside and outside of the vehicle is specified when the vehicle is mounted, and at least two circumferential grooves extending along the equator plane of the tire are arranged on the tread surface. The rib-like land portion extending along the equator of the tire, on or near the tire equator, sandwiched between the circumferential grooves, the center of the rib-shaped land portion in the tire width direction is the tire equator plane Further, when a negative camber is applied to the tire, the tire has a plurality of narrow grooves that are located on the side where the circumferential length of the tread contact area extends and extends in a direction crossing the tire equatorial plane. Of the two circumferential grooves having a portion extending in a direction inclined with respect to the tire radial direction and discontinuous in the tire width direction and sandwiching the rib-like land portion, the circumferential length of the tread contact region Stretched Tire having an asymmetric tread pattern wherein a circumferential groove located on the side is wide.
[0009]
(2) The tire having an asymmetric tread pattern according to (1), wherein the narrow groove has an inclination of 5 to 45 ° with respect to the tire width direction.
[0010]
(3) The tire having an asymmetric tread pattern as described in (1) or (2) above, wherein the narrow groove is open on the tread surface.
[0011]
(4) The tire having an asymmetric tread pattern according to (1), (2) or (3) above, wherein the opening width of the narrow groove is 2 mm or less.
[0012]
(5) The tire having an asymmetric tread pattern according to (1) or (2) above, wherein the narrow groove is closed on the tread surface.
[0013]
(6) A tire having an asymmetric tread pattern in which the orientation with respect to the inside and outside of the vehicle is specified when the vehicle is mounted, and at least two circumferential grooves extending along the equator plane of the tire are arranged on the tread surface. The rib-like land portion extending along the equator of the tire, on or near the tire equator, sandwiched between the circumferential grooves, the center of the rib-shaped land portion in the tire width direction is the tire equator plane In addition, when a negative camber is applied to the tire, the tire has a plurality of dimples that are located on the side where the circumferential length of the tread contact area extends and that has a long axis in the direction crossing the tire equatorial plane. Of the two circumferential grooves sandwiching the rib-like land portion, the circumferential groove located on the side where the circumferential length of the tread contact area extends is wide. Ya.
[0014]
(7) The tire having an asymmetric tread pattern as described in (6) above, wherein the dimple has a major axis having an inclination of 5 to 45 ° with respect to the tire width direction.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Below, the tire of this invention is demonstrated in detail based on drawing.
FIG. 1 shows a tread pattern of a tire for a passenger car according to the present invention. In this example, there are four circumferential grooves 1a to 1d extending along the equator plane O of the tire, and between these circumferential grooves 1a to 1d and Between the tread ends T, land rows 2a and 2b in which blocks are connected to both tread ends T, land portions 3a and 3b on the inner side in the tire width direction, and rib-like land portions 4 on the equator plane O of the tire. Are divided into sections.
[0016]
Further, the land portions 3a and 3b have inclined grooves 5a and 5b that are inclined with respect to the equator plane O of the tire and open outward in the tire width direction. Further, the rib-like land portion 4 has a plurality of narrow grooves 6 extending in a direction crossing the tire equatorial plane O.
[0017]
Here, as shown in FIG. 1, the ground contact shape when a negative camber is applied to the tire is indicated by a thick line, the rib-shaped land portion 4 has a tire width direction center S at the tire equatorial plane O, and the tire has a negative camber on the tire. It is important to locate the tread contact area on the side where the circumferential length extends (the side where the tread ground contact length maximum position mL exists).
[0018]
That is, the rib-like land portion 4 can be disposed in a portion where the belt tension is high and high belt tension is generated due to the wrinkle effect in the tread center portion described above, and where the ground contact area is expanded by extending the ground contact length. Therefore, it is effective for greatly improving the steering stability.
[0019]
Further, as described above, it is also necessary to provide the narrow groove 6 in the rib-like land portion 4 so that the wear does not concentrate on the rib-like land portion 4 in the tread center portion due to high belt rigidity. In other words, since the narrow groove 6 can relieve the circumferential distortion caused by the tire rotation, wear when the distortion generated at the time of kicking is released is suppressed.
[0020]
On the other hand, the provision of the narrow groove 6 causes a decrease in rigidity in the tire width direction of the rib-like land portion 4, and therefore, in order to minimize a decrease in grip force due to this, the strain at the time of ground contact and the lateral direction are reduced. It is necessary to balance rigidity. That is, in the contact area, the narrow groove 6 has a tread tire radius so that the land portion defined by the narrow groove 6 can escape in the circumferential direction and interfere with each other in the width direction to maintain lateral rigidity. It is advantageous to have a portion extending in a direction inclined with respect to the direction.
[0021]
Here, the narrow groove 6 having a portion extending in a direction inclined with respect to the tire radial direction of the tread means that the narrow groove 6 does not extend uniformly in the tire radial direction and the width direction. Specifically, as shown in FIG. 2 in a three-dimensional view in the depth direction of the narrow groove 6 in the rib-like land portion 4, for example, the narrow groove 6 is divided into three in the tire width direction, and the depth direction of each portion is cut. It is preferable to incline the tire with respect to the radial direction of the tire and to give a staggered orientation between adjacent portions. At this time, it is advantageous that the angle α formed by the cuts in the respective portions is in the range of 5 to 30 °.
[0022]
In addition to the example shown in FIG. 2, the narrow groove 6 formed by a cut in a direction inclined with respect to the tire radial direction of the tread extends in a direction inclined with respect to the tire radial direction while twisting the cut. Each narrow groove is important in that the incision from the surface extends in a different direction from the middle, or the incision from the tread surface is divided into multiple parts in the tire width direction from the middle and the extending direction is made different between the divided parts. May be based on being discontinuous in the tire width direction.
[0023]
This is because, by providing the narrow groove 6 extending in such a direction, the circumferential distortion can be avoided, but the continuous groove in the tire width direction is avoided, so that the groove is partitioned in the tire width direction. This is because the deformation can be suppressed and the rigidity can be secured by the interference by the matching walls.
Thus, it is possible to achieve a high level of compatibility between hydroplaning resistance, steering stability and wear resistance, which were difficult to achieve at the same time.
[0024]
Further, in order to reduce so-called pattern noise generated when the road surface and the land portion come into contact with each other when the tire is depressed, it is preferable to incline the narrow groove 6 in a range of 5 to 45 ° with respect to the tire width direction. . That is, if this angle is less than 5 °, the narrow groove and the grounding shape line periodically coincide with each other when the tire rotates, which may cause a large pattern noise. On the other hand, if it exceeds 45 °, the rigidity in the width direction of the rib-like land portion 4 may be lowered, and the steering stability may be adversely affected.
[0025]
Further, the narrow groove 6 is preferably opened on the tread surface from the viewpoint of suppressing wear of the tread center portion. Specifically, if the opening width is 2 mm or less, the circumferential strain is reduced. The effect can be fully exhibited.
Similarly, the narrow groove 6 is preferably closed on the tread surface from the viewpoint of improving steering stability.
[0026]
In place of the narrow groove 6, as shown in FIG. 3, an elliptically dimple 7 having a major axis in the direction crossing the tire equatorial plane is formed, and thus the same as the narrow groove 6 described above. An effect can be obtained. In this case, it is preferable to make the long axis center of the dimple 7 coincide with the center of the rib-like land portion 4 in the tire width direction.
[0027]
【Example】
Invention Example 1
A radial tire for a passenger car having a tread pattern shown in FIG. 1 and having a size of 205 / 65R15 was prototyped. In the tread pattern shown in FIG. 1, the depth of each of the four circumferential grooves is 8 mm, the width is 8 mm for the circumferential grooves 1a and 1d, and the circumferential groove 1b on the grounding length extension side by adding a negative camber angle. 9 mm, and the circumferential groove 1c on the ground contact length decreasing side is 7 mm. Further, the offset amount of the land center S with respect to the tire equator plane O is 5 mm, and the ground contact shape indicated by a thick line indicates when a negative camber angle of 0.5 ° is added.
[0028]
Further, the narrow groove 6 is inclined 15 ° in the tire width direction. As shown in FIG. 2, the narrow groove 6 has an inclination angle of ± 22.5 ° in the tire radial direction within a range of 10 mm in depth in the tire radial direction over the entire width of the rib-like land portion 4 having a width of 18 mm. It is what was cut in. The opening width of the narrow grooves 6 is 0.4 mm, and the distance between the narrow grooves 6 is 30 mm.
[0029]
Invention Example 2
A radial tire for passenger cars having a tread pattern shown in FIG. 3 and having a size of 205 / 65R15 was manufactured. The tread pattern shown in FIG. 3 is the same as that in FIG. 1 except that the dimples 7 whose major axis is inclined by 15 ° in the tire width direction are provided in the rib-like land portion 4 in place of the narrow grooves 6. The dimples 7 have a major axis of 13 mm and a minor axis of 3 mm, and the distance between the dimples 7 is 30 mm.
[0030]
Comparative Example FIG. 4 shows a comparative tread pattern. The basic pattern is the same as that of Invention Example 1, except that the narrow groove 6 is not provided in the rib-like land portion 4, and the center of the width of the rib-like land portion 4 is the tire equator. It is different in that it is placed on the plane O. The depth of the circumferential grooves is 8 mm, the width is 8 mm for the circumferential grooves 1a and 1d, and 7 mm for the circumferential grooves 1b and 1c.
[0031]
After each tire is incorporated in the standard rim and the internal pressure is adjusted to 220 kPa, the hydroplaning performance and steering stability during straight running are sensorially evaluated on the test course, and the vehicle wears over 20,000 km for center wear. It was made to run and the amount of wear of a tread center part was evaluated. The result is shown in Table 1 as an index with the result of Comparative Example 1 being 100, and the larger the index, the better.
[0032]
[Table 1]

[0033]
【The invention's effect】
According to the present invention, it is possible to provide a tire in which the hydroplaning resistance, the steering stability, and the wear resistance performance, which have conventionally been in a contradictory relationship, are compatible at a high level.
[Brief description of the drawings]
FIG. 1 shows a tread pattern according to the present invention.
FIG. 2 is a diagram showing a structure of a narrow groove.
FIG. 3 is a diagram showing another tread pattern according to the present invention.
FIG. 4 is a diagram showing a comparative tread pattern.
[Explanation of symbols]
1a, 1b, 1c, 1d Circumferential groove 2a, 2b Land part row 3a, 3b Land part 4 Rib-like land part 5a, 5b Inclined groove 6 Narrow groove 7 Dimple

Claims (7)

A tire having an asymmetric tread pattern in which the orientation of the vehicle with respect to the inside and outside of the vehicle is designated when the vehicle is mounted, and at least two circumferential grooves extending along the equator plane of the tire are arranged on the tread surface. Having a rib-like land extending along the tire equator on or near the tire equator, sandwiched between directional grooves,
The rib-shaped land portion is located at the center of the tire width direction on the side where the circumferential length of the tread contact area extends when a negative camber is applied to the tire from the tire equatorial plane, and the direction crossing the tire equatorial plane The narrow groove has a portion extending in a direction inclined with respect to the tire radial direction of the tread , is discontinuous in the tire width direction, and further sandwiches the rib-shaped land portion. The tire which has an asymmetric tread pattern characterized by the circumferential groove located in the side where the circumferential direction length of the said tread contact area extends among two circumferential grooves being wide. The tire having an asymmetric tread pattern according to claim 1, wherein the narrow groove has an inclination of 5 to 45 ° with respect to the tire width direction. The tire having an asymmetric tread pattern according to claim 1 or 2, wherein the narrow groove is open on a tread surface. The tire having an asymmetric tread pattern according to claim 1, 2 or 3, wherein the opening width of the narrow groove is 2 mm or less. The tire having an asymmetric tread pattern according to claim 1 or 2, wherein the narrow groove is closed on a tread surface. A tire having an asymmetric tread pattern in which the orientation of the vehicle with respect to the inside and outside of the vehicle is designated when the vehicle is mounted, and at least two circumferential grooves extending along the equator plane of the tire are arranged on the tread surface. Having a rib-like land extending along the tire equator on or near the tire equator, sandwiched between directional grooves,
The rib-shaped land portion is located at the center of the tire width direction on the side where the circumferential length of the tread contact area extends when a negative camber is applied to the tire from the tire equatorial plane, and the direction crossing the tire equatorial plane A circumferential groove located on the side where the circumferential length of the tread contact area extends, out of two circumferential grooves sandwiching the rib-like land portion. A tire having an asymmetric tread pattern characterized by being wide. The tire having an asymmetric tread pattern according to claim 6, wherein the dimple has a major axis inclined by 5 to 45 ° with respect to the tire width direction.

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