JP2004042773A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for preventing grooves to demarcate blocks from being stuffed with snow, and improving the on-snow performance and on-ice performance. <P>SOLUTION: In the pneumatic tire having a plurality of block 4 on a tread part 1, at least one small groove 6 extending in the tire radial direction is formed in wall surfaces of the blocks 4, and the depth D and the width W of the small groove 6 are set to be in a range of 0.3 mm ≤ D ≤ 2.0 mm and in a range of 0.3 mm ≤ W ≤ 2.0 mm, respectively. <P>COPYRIGHT: (C)2004,JPO

Description

【００２３】
表１から判るように、実施例１〜３はいずれも従来例に比べて雪詰まりの影響による氷上制動性能の低下が少ないものであった。一方、比較例１〜３はいずれも細溝の寸法が不適当であるため、圧雪路にて加速後の氷上制動性能が氷上にて加速後の氷上制動性能に比べて大きく低下していた。
【００２４】
【発明の効果】
以上説明したように本発明によれば、トレッド部に複数のブロックを設けた空気入りタイヤにおいて、ブロックの壁面にタイヤ径方向に延びる少なくとも１本の細溝を設け、該細溝の深さＤを０．３ｍｍ≦Ｄ≦２．０ｍｍ、幅Ｗを０．３ｍｍ≦Ｗ≦２．０ｍｍの範囲にしたから、ブロックを区画する溝への雪詰まりを防止し、雪上性能及び氷上性能を改善することができる。しかも、ブロックの壁面に設けた細溝の水膜除去作用によって雪詰まりを防止するので、従来の雪詰まり防止策によって生じていた不都合を回避することができる。
【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のトレッドパターンを示す平面図である。
【図２】本発明の実施形態からなる空気入りタイヤのブロックを拡大して示す斜視図である。
【図３】図２のＸ部の拡大図である。
【符号の説明】
１　トレッド部
２　主溝
３　横溝
４　ブロック
５　サイプ
６　細溝
Ｄ　細溝の深さ
Ｗ　細溝の幅[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic tire having a block pattern, and more particularly, to a pneumatic tire that prevents snow from clogging a groove defining a block and improves performance on snow and performance on ice.
[0002]
[Prior art]
It is a well-known fact that a so-called “snow clogging” phenomenon occurs in which snow is clogged in a groove of a tread portion when running on a snow road that has not been compacted particularly in winter tires. When this snow clogging occurs, the tire cannot fully grasp the new snow when the snow clogged portion comes into contact with the road surface next time. In this case, not only the braking / driving performance on snow is impaired, but also when the vehicle enters a frozen road while biting snow, the performance on ice due to the edge effect may not be sufficiently exhibited.
[0003]
It is considered that the main cause of the snow clogging in the groove is that the adhesive force due to the water film generated between the snow and ice and the block wall surface exceeds the peeling force based on the snow mass and centrifugal force. Therefore, as a method for preventing snow clogging and improving snow removal, it is effective to increase the inclination angle of the block wall surface or set the groove width to increase the mass of snow clogging the groove. However, if the inclination angle of the block wall surface is too large or the groove width is too wide, there is a disadvantage that the performance on snow in the middle period of wear is deteriorated and the originally required ground contact area cannot be secured. In particular, in recent stalles tires, grooves that define blocks intersect in a complicated manner, and it is extremely difficult to increase the angle of inclination of the block wall surface in order to improve snowfall.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a pneumatic tire that can prevent snow clogging in a groove that divides a block and can improve performance on snow and performance on ice.
[0005]
[Means for Solving the Problems]
A pneumatic tire according to the present invention for solving the above-mentioned object is a pneumatic tire in which a plurality of blocks are provided on a tread portion, wherein at least one narrow groove extending in a tire radial direction is provided on a wall surface of the block. The depth D of the groove is in the range of 0.3 mm ≦ D ≦ 2.0 mm, and the width W is in the range of 0.3 mm ≦ W ≦ 2.0 mm.
[0006]
In a pneumatic tire having a block pattern, it is necessary to remove as much as possible a water film serving as an adhesive layer between snow and ice and a block wall surface in order to reduce snow clogging in a groove that partitions the block. In the present invention, a thin groove extending in the tire radial direction is provided on the wall surface of the block in order to efficiently remove a water film generated between snow and ice and the wall surface of the block. As a result, a water film serving as an adhesive layer between the snow and ice and the block wall surface is reduced, so that the snow falls easily due to its own weight and centrifugal force, and the snow clogging is reduced. As a result, the tire of the present invention can catch new snow in the groove between the blocks every rotation, and thus can sufficiently exhibit braking / driving performance on snow. In addition, the possibility of entering the frozen road while biting snow is significantly reduced, so that the performance on ice by the edge effect can be sufficiently exhibited.
[0007]
In the present invention, since the snow clogging is prevented by the water film removing action of the narrow groove provided on the wall surface of the block, the inclination angle of the block wall surface is set to be large or the groove width is widened as in the conventional snow clogging prevention measure. No need to set. Therefore, there is no inconvenience that the tread pattern changes as the wear progresses and the tire performance deteriorates, or that the originally required contact area cannot be secured.
[0008]
It is preferable that the narrow groove is arranged only in a region on the tread surface side of the groove bottom curved portion of the block wall surface. Thereby, generation of cracks due to the narrow grooves can be avoided more reliably.
[0009]
The present invention can be applied to various pneumatic tires, but is particularly preferably applied to winter tires represented by studless tires.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
[0011]
FIG. 1 shows a tread pattern of a pneumatic tire according to an embodiment of the present invention, and FIG. 2 shows an enlarged block diagram thereof. As shown in FIG. 1, the tread portion 1 is provided with a plurality of main grooves 2 extending in the tire circumferential direction and a plurality of lateral grooves 3 extending in the tire width direction. A plurality of blocks 4 are defined by the main groove 2 and the lateral groove 3. Sipe 5 is appropriately formed in block 4.
[0012]
As shown in FIG. 2, a plurality of narrow grooves 6 extending in the tire radial direction are provided on the wall surface of the block 4. The narrow groove 6 is desirably substantially 0 ° with respect to the tire radial direction, but may be within a range of ± 10 ° with respect to the tire radial direction. These fine grooves 6 have a depth D in the range of 0.3 mm ≦ D ≦ 2.0 mm, and a width W of 0.3 mm ≦ W ≦ 2.0 mm, more preferably 0.5 mm ≦ W ≦ 2. It is in the range of 0 mm.
[0013]
In the above-described pneumatic tire, when snow and ice enter the main groove 2 and the lateral groove 3 when traveling on snow, a water film is formed between the wall surface of the block 4 and the snow and ice. Removed. For this reason, the bonding force between the wall surface of the block 4 and the snow and ice is reduced, and the snow falls easily due to the own weight and centrifugal force of the snow and ice, and the snow clogging is reduced. Therefore, the braking / driving performance on snow can be sufficiently exhibited. Further, since the possibility of entering the frozen road while biting snow in the main groove 2 and the lateral groove 3 is significantly reduced, the performance on ice by the edge effect can be sufficiently exhibited.
[0014]
Here, if the depth D of the narrow groove 6 is less than 0.3 mm, the water film cannot be sufficiently removed, and if it exceeds 2.0 mm, the performance on snow and the performance on ice decrease due to the change in block rigidity. I do. If the width W of the narrow groove 6 is less than 0.3 mm, the water film cannot be sufficiently removed. Conversely, if the width W exceeds 2.0 mm, snow easily enters the narrow groove 6 and the snow clogging may occur. Cause.
[0015]
The arrangement density of the narrow grooves 6 is preferably set to 1 to 20 lines / cm. If the arrangement density is less than 1 line / cm, the effect of removing the water film becomes insufficient, and if the arrangement density exceeds 20 lines / cm, it is difficult to specify the width W described above. The cross-sectional shape of the narrow groove 6 is preferably a rectangular shape as shown in the figure, and based on this shape, it is possible to remove the water film while effectively suppressing the entry of snow into the narrow groove 6.
[0016]
It is preferable that the narrow groove 6 is arranged only in a region on the tread surface side of the groove bottom curved portion of the wall surface of the block 4. In other words, when the narrow groove 6 is also arranged at the groove bottom 41 of the groove that partitions the block 4 and at the groove bottom curved portion 42 that connects the groove bottom 41 to the wall surface of the block 4, cracks caused by the narrow groove 6 occur. There is concern. Therefore, by defining the arrangement region of the narrow groove 6 as described above, it is possible to more reliably avoid the occurrence of cracks due to the narrow groove 6.
[0017]
In the pneumatic tire described above, the inclination angle of the wall surface of the block 4 and the groove width of the grooves 2 and 3 that define the block 4 do not need to be set particularly wide. It is not difficult to secure a necessary ground contact area.
[0018]
【Example】
In the pneumatic tire having a block pattern of a tire size of 155R138PR, conventional examples, examples 1 to 3 and comparative examples 1 to 3 in which narrow grooves were formed on the block wall surfaces as shown in Table 1 were manufactured.
[0019]
With respect to these test tires, the braking performance on ice after acceleration on ice and the braking performance on ice after acceleration on snowy roads were evaluated by the following test methods. The results are shown in Table 1.
[0020]
Braking performance on ice after acceleration on ice:
The test tire was mounted on a four-wheel drive van equipped with an anti-lock brake system (ABS) at an air pressure of 230 kPa, accelerated to 40 km / h on ice, then ABS-bred on ice, and the braking distance was measured. This measured value was used as a reference (100).
[0021]
Braking performance on ice after accelerating on a snowy road:
The test tire was mounted on a four-wheel drive van equipped with ABS at an air pressure of 230 kPa, accelerated to 40 km / h on a snow-covered road, and then subjected to ABS braking on ice, and the braking distance was measured. The evaluation results are shown as indices for each tire, where the braking distance on ice after acceleration on ice is 100. The larger the index value is, the better the braking performance on ice after acceleration on a snow-covered road is, that is, the lower the braking performance on ice due to the snow clogging is.
[0022]
[Table 1]

[0023]
As can be seen from Table 1, all of Examples 1 to 3 showed less reduction in braking performance on ice due to the influence of snow clogging than the conventional example. On the other hand, in all of Comparative Examples 1 to 3, the dimensions of the narrow grooves were inappropriate, so that the braking performance on ice after acceleration on a snow-covered road was significantly lower than the braking performance on ice after acceleration on ice.
[0024]
【The invention's effect】
As described above, according to the present invention, in a pneumatic tire in which a plurality of blocks are provided on a tread portion, at least one narrow groove extending in the tire radial direction is provided on a wall surface of the block, and a depth D of the narrow groove is provided. 0.3 mm ≦ D ≦ 2.0 mm and the width W within the range of 0.3 mm ≦ W ≦ 2.0 mm, thereby preventing snow clogging in the groove defining the block and improving the performance on snow and the performance on ice. be able to. Moreover, since the snow clogging is prevented by the water film removing action of the narrow groove provided on the wall surface of the block, it is possible to avoid the inconvenience caused by the conventional snow clogging prevention measures.
[Brief description of the drawings]
FIG. 1 is a plan view showing a tread pattern of a pneumatic tire according to an embodiment of the present invention.
FIG. 2 is an enlarged perspective view showing a block of the pneumatic tire according to the embodiment of the present invention.
FIG. 3 is an enlarged view of a portion X in FIG. 2;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tread part 2 Main groove 3 Lateral groove 4 Block 5 Sipe 6 Narrow groove D Narrow groove depth W Narrow groove width

Claims (2)

In a pneumatic tire provided with a plurality of blocks on a tread portion, at least one narrow groove extending in the tire radial direction is provided on a wall surface of the block, and a depth D of the narrow groove is set to 0.3 mm ≦ D ≦ 2.0 mm. And a pneumatic tire having a width W in a range of 0.3 mm ≦ W ≦ 2.0 mm. The pneumatic tire according to claim 1, wherein the narrow groove is arranged only in a region on the tread surface side of the groove bottom curved portion of the block wall surface.

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