JP2005059634A - Pneumatic tire for ice or snow road - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for an ice or snow road with both of high ice braking performance and high eccentric abrasion resistance. <P>SOLUTION: This pneumatic tire for an ice or snow road is provided with a plurality of vertical grooves 2 extending on a tread face 1 in a tire peripheral direction, and a plurality of horizontal grooves 3 crossing the vertical grooves 2. These vertical grooves 2 and horizontal grooves 3 form a large number of blocks 4, and one or more sipes 5 extending in a tire width direction are provided to each block 4. A hoop block 5 having a peak face 5a lower than a tread of a block 4 by one step is formed around the block 4, and a frame sipe 7 having depth in a tire radial direction is formed at a boundary between the block 4 and the hoop block 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

この結果、本発明タイヤは従来例１及び２に比較して、氷上制動性能及び耐偏摩耗性能が高いレベルで両立していることがわかる。
【００１９】
【発明の効果】
上述したように、本発明の氷雪路用空気入りタイヤは、ブロックの周囲に、ブロック踏面より一段低い頂面を有する箍ブロックを形成し、ブロックと箍ブロックとの境界にタイヤ径方向に深さを有する枠サイプを形成したので、サイプの形成により踏面部の接地性を向上させて氷上制動性能を確保すると共に、サイプの形成により剛性が低下したブロックの倒れ込みを枠サイプを隔ててブロックの周囲に形成した箍ブロックが支えることにより偏摩耗を防止することができる。
【図面の簡単な説明】
【図１】本発明の氷雪路用空気入りタイヤのトレッド面の一例を示す一部平面図である。
【図２】本発明の氷雪路用空気入りタイヤのブロックの斜視図である。。
【図３】図２のＸーＸ矢視断面図である。
【図４】（ａ）〜（ｅ）は本発明の氷雪路用空気入りタイヤのブロックの形態の例を示す平面図である。
【図５】（ａ）〜（ｄ）本発明の効果を確認するために採用した各タイヤのブロックの形態を示す図で、上段に平面図を下段にＹーＹ矢視断面図をそれぞれ示す。
【符号の説明】
１ トレッド面
２ 縦溝
３ 横溝
４ ブロック
５ サイプ
６ 箍ブロック
７ 枠サイプ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire for icy and snowy roads, and more particularly, to a pneumatic tire for icy and snowy roads having both on-ice braking performance and uneven wear resistance performance.
[0002]
[Prior art]
In order to ensure braking / driving performance on a snowy road surface, an ice / snow road pneumatic tire is generally provided with a plurality of vertical grooves extending in the tire circumferential direction and a plurality of horizontal grooves extending in the tire width direction on the tread surface. A tread pattern in which a large number of blocks are defined by vertical and horizontal grooves is adopted. In addition, the surface of each block is provided with a notch called sipe in the tire width direction to reduce the rigidity of the tread surface to improve the ground contact property, and to use the edge effect due to capillary action and water film destruction on the ice surface I try to get higher traction performance.
[0003]
However, if too many sipes are formed excessively on the surface of each block, there is a problem that the rigidity of the block is excessively lowered and uneven wear called so-called heel and toe wear occurs on the block surface.
[0004]
Many proposals have heretofore been made in order to achieve both on-ice braking performance and uneven wear resistance, which are in a trade-off relationship in this manner (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-165507
[Problems to be solved by the invention]
However, each of these proposals has advantages and disadvantages, and none of them has been able to achieve both performances at a high level.
[0007]
An object of the present invention is to provide a pneumatic tire for icy and snowy roads that solves the conventional problems and achieves both high braking performance on ice and uneven wear resistance at a high level.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a pneumatic tire for icy and snowy roads of the present invention is provided with a plurality of vertical grooves extending in the tire circumferential direction on the tread surface and a plurality of horizontal grooves intersecting the vertical grooves, and the vertical grooves In a pneumatic tire for snowy and snowy roads in which a plurality of blocks are formed by lateral grooves and each block is provided with one or more sipes extending in the tire width direction, a top surface that is one step lower than the tread surface of the block around the block And a frame sipe having a depth in the tire radial direction is formed at the boundary between the block and the heel block.
[0009]
In this way, a saddle block having a top surface that is one step lower than the block tread surface is formed around the block, and a frame sipe having a depth in the tire radial direction is formed at the boundary between the block and the saddle block. This improves the ground contact performance of the tread surface to ensure braking performance on ice, and also supports uneven wear due to the saddle block formed around the block across the frame sipe that supports the falling of the block whose rigidity has decreased due to the formation of the sipe. Can be prevented.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each drawing, the same constituent elements are given the same reference numerals, and redundant description is omitted.
[0011]
FIG. 1 is a plan view showing an example of a tread surface of a pneumatic tire for icy and snowy roads of the present invention. The pneumatic radial tire for an snowy and snowy road is provided with a plurality of vertical grooves 2 extending in the tire circumferential direction T and a plurality of horizontal grooves 3 extending in the tire width direction intersecting with the tread surface 1. Thus, the block 4 is partitioned.
[0012]
Each block 4 is formed with one or more sipes 5 (three in the figure) in the tire width direction, and around the block 4, as shown in FIGS. A saddle block 6 having a low top surface 6a is formed. A frame sipe 7 having a depth in the tire radial direction is formed at the boundary between the block 4 and the heel block 6.
[0013]
A step d between the tread surface of the block 4 and the top surface 6a of the saddle block 6, a depth Da of the sipe 5, a depth Db of the frame sipe 7 from the tread surface of the block 4, and a depth D of the lateral groove 3 In the meantime, the respective values are set so that d <Da <D and d <Db <D are satisfied. By setting in this way, the grounding performance of the tread portion of the block 4 is improved to ensure braking performance on ice, and the saddle block 6 surrounding the fall of the block 4 whose rigidity has been lowered due to the formation of the sipe 5 is supported. Thus, uneven wear can be prevented. The relationship between the depth Da of the sipe 5 and the depth Db from the tread surface of the block 4 of the frame sipe 7 is preferably Da <Db. Accordingly, since the shear force from the road surface can be received by the entire block 4, it is possible to suppress generation of cracks at the bottom of the sipe 5 and heel and toe wear for each small block partitioned by the sipe 5.
[0014]
The tread pattern in the pneumatic tire for icy and snowy roads of the present invention is not limited to the pattern illustrated in FIG. 1, and is illustrated in FIGS. 4A to 4E due to the difference in the shape of the vertical groove 2 and the horizontal groove 3. The pattern which combined the block 4 which has such various plane forms may be sufficient. Further, as illustrated, the shape of the sipe 5 may be a zigzag sipe that is inclined with respect to the tire width direction. In any case, a saddle block 6 having a top surface 6a that is one step lower than the tread surface of the block 4 is formed around the block 4, and the boundary between the block 4 and the saddle block 6 is formed in the tire radial direction. A frame sipe 7 having a depth is formed.
[0015]
As described above, the pneumatic tire for snowy and snowy road according to the present invention prevents uneven wear by preventing the block 4 whose rigidity has been lowered due to the formation of the sipe 4 from falling down by the eaves block 6 surrounding the block 4. Therefore, the formation density of the sipes 5 in the block 4 can be increased and the braking performance on ice can be ensured. Therefore, the braking performance on ice and the anti-uneven wear performance that are in a trade-off relationship can be achieved at a high level. .
[0016]
【Example】
The tire size (11R22.5) and the size of the block 4 (circumferential length L = 30.0 mm, widthwise length W = 20.0 mm) and the arrangement are the same, and the form of the block is as shown in Table 1 Conventional tires (conventional examples 1 and 2), tires of the present invention (examples) and comparative tires (comparative examples) having the tread pattern of FIG. In addition, the width w of the heel block 6 in the tire of the present invention was 2.0 mm.
[0017]
These four types of tires were evaluated for braking performance on ice and uneven wear resistance by the following methods, and are listed in Table 1 by index display with Conventional Example 1 being 100. The larger the value, the better.
[Evaluation of braking performance on snow and ice]
Each tire was mounted on a heavy-duty vehicle (constant load), and the braking distance was measured by lock braking from an initial speed of 40.0 km / h on an icy road surface. [Evaluation of uneven wear resistance]
Each tire is mounted on a heavy-duty vehicle (constant load), and after traveling 10,000 km on an asphalt road with a normal load applied, the occurrence of heel and toe wear and changes in the appearance of the entire tread surface The situation was examined and evaluated based on the results.
[0018]
[Table 1]

As a result, it can be seen that the tire of the present invention is compatible with the braking performance on ice and the uneven wear resistance at a high level as compared with the conventional examples 1 and 2.
[0019]
【The invention's effect】
As described above, the pneumatic tire for snowy and snowy roads of the present invention forms a saddle block having a top surface that is one step lower than the block tread surface around the block, and has a depth in the tire radial direction at the boundary between the block and the saddle block. Since the frame sipe with the sipe is formed, the grounding property of the tread surface is improved by forming the sipe to secure the braking performance on ice, and the fall of the block whose rigidity has been reduced by the formation of the sipe is separated around the block by the frame sipe. Uneven wear can be prevented by supporting the eaves block formed on.
[Brief description of the drawings]
FIG. 1 is a partial plan view showing an example of a tread surface of a pneumatic tire for icy and snowy roads according to the present invention.
FIG. 2 is a perspective view of a block of a pneumatic tire for icy and snowy roads of the present invention. .
3 is a cross-sectional view taken along the line XX in FIG. 2;
4 (a) to 4 (e) are plan views showing an example of a block form of a pneumatic tire for snowy and snowy roads according to the present invention.
FIGS. 5A to 5D are diagrams showing the form of each tire block adopted for confirming the effects of the present invention, and a plan view is shown in the upper part and a cross-sectional view taken along the arrow YY is shown in the lower part, respectively. .
[Explanation of symbols]
1 Tread surface 2 Vertical groove 3 Horizontal groove 4 Block 5 Sipe 6 箍 Block 7 Frame sipe

Claims (3)

A plurality of vertical grooves extending in the tire circumferential direction and a plurality of horizontal grooves intersecting the vertical grooves are provided on the tread surface, and a plurality of blocks are formed by the vertical grooves and the horizontal grooves, and each block extends in the tire width direction. In pneumatic tires for icy and snowy roads with one or more sipes,
For ice and snowy roads in which a saddle block having a top surface that is one step lower than the tread surface of the block is formed around the block, and a frame sipe having a depth in the tire radial direction is formed at the boundary between the block and the saddle block Pneumatic tire. The step between the tread of the block and the top surface of the saddle block is d, the depth of the sipe is Da, the depth of the frame sipe from the tread of the block is Db, and the depth of the lateral groove is D, The pneumatic tire for ice and snowy road according to claim 1, wherein the relation of d <Da <D and d <Db <D is satisfied. The pneumatic tire for ice and snowy road according to claim 2, wherein a relationship between a depth Da of the sipe and a depth Db from the tread surface of the block of the sipe is Da <Db.

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