JP4262813B2 - studless tire - Google Patents

Description

【００１５】
【表２】

【００１６】
この表１から明らかなように、本発明タイヤ（実施例１〜９）は、サイプ内壁面を平坦に形成したタイヤ（比較例１）に比べて氷上摩擦性能が著しく向上していた。また、サイプ内壁面に凸部とディンプルを形成してこれらを噛み合わせるようにしたタイヤ（比較例２）に対しても、本発明タイヤは氷上摩擦性能が向上していた。
【００１７】
小ブロック同士の最短距離ｙｅが小さい実施例７と大きい実施例４では、十分なエッジ効果と接地面積が得られないため実施例１，５，６に比べて氷上摩擦性能の向上効果が小さかった。小ブロック同士の最短距離ｙｅは０．０５〜１．０ｍｍであることが望ましい。また、実施例１０，１１の結果から、直方体以外の小ブロックの形状でも効果があることが分かる。小ブロックとしては任意の立体形状を選択し、各形状に応じてその寸法を適宜設定すれば良い。
小ブロックの高さｈがサイプの溝幅に対して小さい比較例３では、小ブロック同士の十分な噛み合わせとサイプ内の排水用の空間を十分に確保できないため、小ブロック高さが大きい実施例１，８，９に比べて氷上摩擦性能の向上効果が小さかった。この小ブロック高さはサイプ溝幅の０．５５〜０．９５倍であることが必要である。
【００１８】
【発明の効果】
以上説明したように本発明によれば、トレッド表面にタイヤ周方向に延びる複数本の主溝と、この主溝に交差する複数の副溝とでブロックを形成し、さらに前記ブロックに少なくとも１本のサイプをタイヤ幅方向に延びるように設けたスタッドレスタイヤにおいて、総サイプ数の３０％以上のサイプに対し、サイプ内壁面に複数の小ブロックを形成し、これら小ブロックの前記内壁面からの高さを前記サイプの溝幅の０．５５〜０．９５倍とし、その対面する内壁面の小ブロック同士を無負荷状態では互いに非接触でタイヤ周方向に重複し、かつ前記ブロックの倒れ込み時には互いに接触するように配置したことにより、ブロックの倒れ込みを抑制すると共に、サイプエッジによる掘り起こし効果を十分に確保し、氷上摩擦性能を向上することができる。従って、本発明のスタッドレスタイヤは、氷結路面走行用タイヤとしての理想的性能を発揮することが可能である。
【図面の簡単な説明】
【図１】本発明の実施形態からなるスタッドレスタイヤのトレッドパターンを例示する平面図である。
【図２】（ａ）は図１におけるサイプを示す断面図、（ｂ）はそのブロック倒れ込み時における状態を示す断面図である。
【図３】（ａ）〜（ｅ）は本発明のスタッドレスタイヤにおける小ブロックの形状を例示する斜視図である。
【図４】（ａ）は実施例１〜９において小ブロックが直方体である場合のブロックを示す断面図、（ｂ）はそのタイヤ周方向の投影図である。
【図５】（ａ）は実施例１０において小ブロックが半球である場合のブロックを示す断面図、（ｂ）はそのタイヤ周方向の投影図である。
【図６】（ａ）は実施例１１において小ブロックが半円柱のエッジを球面にした立体である場合のブロックを示す断面図、（ｂ）はそのタイヤ周方向の投影図である。
【図７】（ａ）は比較例２において凸部及びディンプルが直方体である場合のブロックを示す断面図、（ｂ）はそのタイヤ周方向の投影図である。
【図８】従来のスタッドレスタイヤにおけるブロックの倒れ込み現象を示す断面図である。
【符号の説明】
１ トレッド表面
２ 主溝
３ 副溝
４ ブロック
５ サイプ
５ａ，５ｂ サイプの内壁面
６ａ，６ｂ 小ブロック[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a studless tire suitable for running on ice, and more particularly, to a studless tire having improved frictional performance on ice.
[0002]
[Prior art]
In conventional studless tires, in order to further improve the friction performance on ice, for example, a flexible rubber is used to increase the adhesive friction force, and a large number of sipes are formed on the block to enhance the effect of digging up with sipe edges. It is done.
However, in a studless tire using a flexible rubber, the block rigidity is remarkably lowered, and the contact area is reduced due to the collapse of the block. Therefore, it is difficult to increase the number of sipes. That is, when the number of sipes is increased in a studless tire using a flexible rubber, each sub-block divided by the sipes S is in the traveling direction of the block B when braking on an icing road surface as shown in FIG. It falls in the reverse direction and the lower end rear part is in a state of floating from the road surface R. As a result, the contact area of the block B is reduced, the frictional force is reduced, and the braking performance on ice is lowered.
[0003]
As a means for preventing the block from falling down, a studless tire (Japanese Patent Laid-Open No. 5-58118) has been proposed in which convex portions and dimples are formed on the inner wall surface of the sipe so as to engage with each other. However, in this tire, although the collapse of the block is suppressed, there remains a problem that the digging effect by the sipe edge is poor. Further, as a studless tire having a configuration similar to the above-mentioned Japanese Patent Laid-Open No. 5-58118, a studless tire having a convex portion formed on the inner wall surface of the sipe and having a sipe groove width composed of a wide portion and a narrow portion (Japanese Patent Laid-open No. No. 4-345504 gazette) is known, but with this tire, excellent drainage, which is its original purpose, can be ensured, but the effect of suppressing the block collapse cannot be exhibited.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a studless tire that suppresses the collapse of a block, sufficiently secures a digging effect by a sipe edge, and improves the friction performance on ice.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a studless tire according to the present invention has a tread surface formed with a plurality of main grooves extending in the tire circumferential direction and a plurality of sub-grooves intersecting the main grooves. In a studless tire provided with at least one sipe extending in the tire width direction , a plurality of small blocks are formed on a sipe inner wall surface for a sipe of 30% or more of the total sipe number, and the inner wall surface of these small blocks The height from the sipe is 0.55 to 0.95 times the groove width of the sipe, and the small blocks of the inner wall surfaces facing each other are not contacted with each other in the unloaded state and overlap each other in the tire circumferential direction. They are arranged so as to come into contact with each other when they fall down.
[0006]
In this way, by forming a plurality of small blocks on the inner wall surface of the sipe and arranging the small blocks on the inner wall surface facing each other so as to be combined with each other, the small blocks facing each other mesh with each other when the block collapses and the block collapses Suppressing and preventing close contact between sipe inner walls facing small blocks, ensuring sufficient drainage, and allowing the sipe inner walls to be slightly displaced from each other, ensuring sufficient digging effect by sipe edge Therefore, the friction performance on ice can be improved. If the number of sipes with small blocks is too small, the effect of improving the friction performance on ice is low. Therefore, it is necessary to form small blocks on sipes of 30% or more of the total number of sipes in the tire.
[0007]
In addition, in the studless tire of the present invention, it is desirable to arrange sipes so that the shortest distance between the small blocks that are assembled with each other is 0.05 to 1.0 mm, and by ensuring the shortest distance, block collapse is suppressed. The increase in the contact area due to the sipe and the excavation effect due to the sipe edge are highly balanced, and a superior friction performance on ice can be obtained.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a plan view showing an example of a tread pattern of a studless tire of the present invention. In FIG. 1, a tread surface 1 is provided with a plurality of main grooves 2 extending in the tire circumferential direction and a plurality of sub grooves 3 intersecting with the main grooves 2. A block pattern composed of a plurality of blocks 4 partitioned by the sub-grooves 3 is formed. Each block 4 is formed with two sipes 5 extending in the tire width direction, and the blocks 4 are divided into three sub-blocks by the sipes 5.
[0009]
As shown in FIG. 2 (a), a plurality of small blocks 6a and 6b projecting from the inner wall surfaces 5a and 5b are formed on the inner wall surfaces 5a and 5b facing the sipe 5, respectively. These small blocks 6a and 6b are arranged so as to be assembled without contact with each other in a no-load state, that is, overlap in the tire circumferential direction in a side view of the tire. And when the block 4 falls down, as shown in FIG.2 (b), the small blocks 6a and 6b which face are meshed | engaged with each other.
[0010]
The shortest distance ye between the small blocks 6a and 6b is set to be 0.05 to 1.0 mm. This shortest distance ye defines the amount of block collapse for enabling the digging effect due to the edge of the sipe 5, and if it is less than 0.05 mm, the digging effect due to the sipe edge becomes insufficient. This is not preferable because the contact area of the block 4 is reduced and the frictional resistance is lowered.
The groove width of the sipe 5 is set to 0.3 to 2.0 mm. If the height of the small blocks 6a, 6b is lower than the groove width of the sipe 5, it is difficult for the small blocks 6a, 6b to engage with each other. Therefore, the height of the small blocks 6a, 6b from the inner wall surfaces 5a, 5b is sipe. 5 is preferably set to 0.55 to 0.95 times the groove width.
[0011]
According to the present invention, as described above, a plurality of small blocks 6a and 6b are formed on the inner wall surfaces 5a and 5b of the sipe 5, and the small blocks 6a and 6b facing each other are arranged in a non-contact manner. Thus, when the block 4 falls, the small blocks 6a and 6b facing each other mesh with each other, and the block 4 can be prevented from falling. Moreover, since the inner wall surfaces 5a and 5b facing the sipe 5 can be shifted from each other based on the shortest distance ye, the digging effect by the sipe edge can be sufficiently ensured. Therefore, since the digging effect by the sipe edge can be sufficiently obtained while ensuring a sufficient contact area, it is possible to improve the friction performance on ice.
As shown in FIGS. 3A to 3E, as the three-dimensional shape of the small block 6, an arbitrary shape such as a hemisphere, a rectangular parallelepiped, a chamfered rectangular parallelepiped, a cylinder, and a semicylindrical can be selected. The dimensions may be set as appropriate.
[0012]
【Example】
In a studless tire having a tire size of 185 / 65R14, the tread pattern shown in FIG. 1, and a sipe groove width of 0.6 mm, a comparative tire (Comparative Example 1) in which the inner wall surface of the sipe is formed flat, Tires of the present invention (Examples 1 to 9) and comparative tires (Comparative Example 3) in which sipes shown in FIG. 4 are arranged, and tires of the present invention in which sipes shown in FIGS. For the comparative tire (Comparative Example 2) in which convex portions and dimples are formed on the inner wall surface of the sipe shown in FIG. 7 and meshed with each other, the friction performance on ice is evaluated by the following test method. The results are shown in Table 1.
[0013]
That is, the evaluation of the frictional performance on ice was performed by mounting each test tire on a passenger car with an air pressure of 200 kPa and measuring the braking distance from the running state at a speed of 40 km / h on the icing road surface until the brake was applied. . The evaluation results are shown as an index with the reciprocal of the measured value of Comparative Example 1 as 100. The larger the index value, the better the friction performance on ice.
In each of the tires, the compounds shown in Table 2 were used as the rubber composition constituting the tread portion.
[0014]
[Table 1]

[0015]
[Table 2]

[0016]
As is apparent from Table 1, the tires of the present invention (Examples 1 to 9) had significantly improved on-ice friction performance as compared with the tire (Comparative Example 1) having a sipe inner wall surface formed flat. In addition, the tire of the present invention has improved friction performance on ice, compared to a tire (Comparative Example 2) in which convex portions and dimples are formed on the inner wall surface of the sipe and meshed with each other.
[0017]
In Example 7 in which the shortest distance ye between the small blocks is small and Example 4 in which the short block is large, a sufficient edge effect and a contact area cannot be obtained, so the effect of improving the friction performance on ice is small compared to Examples 1, 5, and 6. . The shortest distance ye between the small blocks is preferably 0.05 to 1.0 mm. In addition, it can be seen from the results of Examples 10 and 11 that the shape of the small block other than the rectangular parallelepiped is also effective. An arbitrary three-dimensional shape may be selected as the small block, and the dimensions may be appropriately set according to each shape.
In Comparative Example 3 in which the height h of the small block is small relative to the groove width of the sipe, the small block height is large because sufficient engagement between the small blocks and sufficient space for drainage in the sipe cannot be secured. Compared to Examples 1, 8, and 9, the effect of improving the friction performance on ice was small. The small block height needs to be 0.55 to 0.95 times the sipe groove width.
[0018]
【The invention's effect】
As described above, according to the present invention, a block is formed by a plurality of main grooves extending in the tire circumferential direction on the tread surface and a plurality of sub-grooves intersecting the main grooves, and at least one block is formed in the block. In the studless tire provided with the sipe extending in the tire width direction, a plurality of small blocks are formed on the inner wall surface of the sipe with respect to a sipe of 30% or more of the total number of sipe, and the height of the small blocks from the inner wall surface is increased. The width of the groove is 0.55 to 0.95 times the groove width of the sipe, and the small blocks of the inner wall surfaces facing each other are not in contact with each other in the unloaded state and overlap in the tire circumferential direction, and when the blocks are collapsed, by was placed in contact, as well as suppress collapsing of the blocks, the digging effect is sufficiently ensured by Saipuejji, child improve friction performance on ice Can. Therefore, the studless tire of the present invention can exhibit ideal performance as a tire for running on an icy road surface.
[Brief description of the drawings]
FIG. 1 is a plan view illustrating a tread pattern of a studless tire according to an embodiment of the invention.
2A is a cross-sectional view showing a sipe in FIG. 1, and FIG. 2B is a cross-sectional view showing a state when the block is collapsed;
FIGS. 3A to 3E are perspective views illustrating the shape of small blocks in the studless tire of the present invention.
4A is a cross-sectional view showing a block when the small block is a rectangular parallelepiped in Examples 1 to 9, and FIG. 4B is a projection view in the tire circumferential direction.
5A is a cross-sectional view showing a block when the small block is a hemisphere in Example 10, and FIG. 5B is a projection view in the tire circumferential direction thereof.
6A is a cross-sectional view showing a block in a case where the small block is a solid with a semi-cylindrical edge made into a spherical surface in Example 11, and FIG. 6B is a projection view in the tire circumferential direction thereof.
7A is a cross-sectional view showing a block in the case where the convex portions and the dimples are cuboids in Comparative Example 2, and FIG. 7B is a projected view in the tire circumferential direction.
FIG. 8 is a cross-sectional view showing a block collapse phenomenon in a conventional studless tire.
[Explanation of symbols]
1 Tread surface 2 Main groove 3 Sub groove 4 Block 5 Sipe 5a, 5b Inner wall surface 6a, 6b of Sipe Small block

Claims (3)

A block is formed by a plurality of main grooves extending in the tire circumferential direction on the tread surface and a plurality of sub grooves intersecting the main grooves, and at least one sipe is provided in the block so as to extend in the tire width direction. In a studless tire, for a sipe of 30% or more of the total number of sipe, a plurality of small blocks are formed on the inner wall surface of the sipe, and the height of these small blocks from the inner wall surface is 0.55 of the groove width of the sipe. A studless tire which is arranged to be 0.95 times and the small blocks of the inner wall surfaces facing each other are arranged in a non-contact state so as not to contact each other and overlap each other in the tire circumferential direction, and to contact each other when the block collapses . The studless tire according to claim 1, wherein the shortest distance between the small blocks on the inner wall surfaces facing each other is 0.05 to 1.0 mm. The studless tire according to claim 1 or 2, wherein the groove width of the sipe is 0.3 to 2.0 mm .

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