JP2004098926A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high performance pneumatic tire having both on-ice/snow performance and wet performance at a high degree by improving a tread pattern for optimizing the numbers of main peripheral grooves and sipes provided in blocks. <P>SOLUTION: The pneumatic tire comprises an circularly formed tread portion, a pair of sidewall portions arranged ranging from both sides of the tread portion to the inside in a tire radial direction, and bead portions ranging to the inside of the sidewall portions in the tire radial direction. The four main grooves 1 extending to the peripheral direction and the blocks 3 sectioned by the main grooves 1 and lug grooves 2 crossing them are formed in the tread surface of the tread portion. The blocks 3 have three sipes 5a, 4, 5b in the cross direction, at least one of which is a one-side open sipe tied to the main groove 1 at one side. The lug grooves 2 are offset in blocks in the peripheral direction. <P>COPYRIGHT: (C)2004,JPO

Description

【００３５】
（２）氷上ブレーキ試験
場所：テストコース
路面：氷上
【００３６】
【表２】

【００３７】
（３）雪上トラクション試験
場所：テストコース
路面：雪上
【００３８】
【表３】

【００３９】
【発明の効果】
以上説明してきたように、本発明によれば、トレッドパターンを改良することにより、周方向主溝およびブロックに設けるサイプの本数を適正化して、特に摩耗中期までの氷雪上性能と、新品時から摩耗中期以降履き潰し時までのウェット性能とを高度に両立させた高性能の空気入りタイヤを提供することが可能となる。
【図面の簡単な説明】
【図１】本発明の一好適例の空気入りタイヤのブロックパターンを示す展開平面図である。
【図２】本発明の他の好適例の空気入りタイヤのブロックパターンを示す展開平面図である。
【図３】従来例の空気入りタイヤのブロックパターンを示す展開平面図である。
【符号の説明】
１　周方向主溝
２　ラグ溝
３　ブロック
４　オープンサイプ
５ａ、５ｂ　片側オープンサイプ
６　丸穴部分
１１、１２　周方向主溝
１３　副溝
１４　幅方向溝
１５、１６、１７　ブロック列
１８　オープンサイプ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire with improved tread pattern to improve the performance on ice and snow until the middle wear and the wet performance from the time of new wear to the time of crushing after the middle wear. .
[0002]
[Prior art]
The tread pattern of a pneumatic tire has been studied from various viewpoints. For example, it is generally effective to increase the edge density generated by blocks and sipes projected in the width direction to improve so-called ice and snow performance such as braking performance on ice and snow road surface and traction performance on snow. It has been known.
[0003]
For example, Patent Document 1 discloses a plurality of circumferential grooves (three in FIG. 1 and [0010] in the document) and a width dividing a land row formed between the circumferential grooves in a tire width direction. In a tire having blocks defined by directional grooves, each block is subdivided by at least two sipes (two in FIG. 1 and [0011] in the literature) that open into the circumferential grooves, and By forming a projecting land portion in the circumferential direction at the bottom of at least one groove, and making the surface a step so that the surface comes into sliding contact with the outer contour of the tire when rolling on the tire, the performance on ice and snow is improved. An improved tire is described.
[0004]
On the other hand, in order to secure so-called wet performance such as braking performance and steering stability on a wet road surface in a pneumatic tire, it is advantageous to increase the see-through area by using circumferential grooves as straight grooves. Therefore, when the performance on ice and snow is improved by increasing the edge component in the width direction in the circumferential groove, the see-through region becomes narrower than the groove width of the circumferential main groove, and the wet performance deteriorates. Occurs.
[0005]
On the other hand, as a technique for achieving both the performance on ice and snow and the wet performance, for example, Patent Document 2 discloses three circumferential main grooves extending linearly in the circumferential direction, and a gap between the circumferential main grooves. A circumferential narrow groove formed in a zigzag shape in the circumferential direction, a width direction groove for dividing a land portion defined by each circumferential groove into blocks, and a sipe formed in each block and extending in the tread width direction (implemented) In the example, two tires are described, and the width of each of the circumferential main groove and the circumferential narrow groove is set to a predetermined dimension.
[0006]
As in the tires described in Patent Literature 1 and Patent Literature 2, in a tread pattern of a conventional pneumatic tire, it is common to provide three circumferential main grooves and provide about two or less sipes in a block. Met. Further, the lug grooves in the conventional tread pattern are offset (the phases are shifted) between the blocks adjacent to each other with the circumferential main groove interposed therebetween, but there are many cases where the lug grooves have the same phase.
[0007]
In contrast to the tires described in Patent Literature 1 and Patent Literature 2, for example, Patent Literature 3 includes four circumferential main grooves, and the center rib among the ribs defined by the circumferential main grooves is formed on both sides. The main groove has a lug groove alternately from the main groove and a length of 50% or more of the width with respect to the center rib, and has a connecting groove having a sipe at the groove bottom for connecting the lug groove in a circumferential direction. There is described a technique for improving uneven wear resistance and the like in addition to performance on ice and snow and wet performance by using tires. The tire block described in Patent Literature 3 is provided with three sipes from the circumferential main groove.
[0008]
[Patent Document 1]
JP-A-2002-127716 ([0003], [FIG. 1], etc.)
[Patent Document 2]
JP-A-11-180113 (Claims, etc.)
[Patent Document 3]
Japanese Patent Application Laid-Open No. 2000-158916 (Claims, etc.)
[0009]
[Problems to be solved by the invention]
Generally, the sipe and the lug groove formed on the tread gradually disappear from the viewpoint of securing the block rigidity when the wear of the tread exceeds 50%. Therefore, in the conventional tire having three circumferential main grooves, the negative at the end of wear is reduced, and there is a problem that the wet performance cannot be sufficiently secured.
[0010]
We also want to increase the number of sipes to improve performance on ice, but on the other hand, increasing the number of sipes tends to reduce block durability and uneven wear resistance. Often, only two or less sipes could be inserted.
[0011]
In addition, when the tire rolls on snow, the snow is sheared by compressing the snow in the lug grooves between the blocks. In this case, if the lug grooves are not out of phase, the continuous snow column No shearing occurs. In the conventional tire, there is a portion where lug grooves have the same phase, so that snow column shearing is discontinuous, and there is a problem that the effect of improving the on-snow performance by the lug grooves cannot be sufficiently obtained.
[0012]
Accordingly, an object of the present invention is to improve the tread pattern to optimize the number of sipes provided in the circumferential main groove and the block, and to provide a high-performance pneumatic pneumatic tire that has both high performance on ice and snow and high wet performance. To provide tires.
[0013]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventor has found that the above configuration can achieve the above object, and has completed the present invention. That is, the pneumatic tire of the present invention is as follows.
[0014]
(1) A ring-shaped tread portion, a pair of sidewall portions disposed radially inward from both sides of the tread portion in the tire radial direction, and a bead portion continuous with the sidewall portion radially inward in the tire radial direction. In the pneumatic tire provided,
On the tread portion of the tread portion, a block divided by four main grooves extending in the circumferential direction and a lug groove intersecting with the main groove is formed, and the block has three sipes in the width direction, A pneumatic tire, wherein at least one of the sipes is a one-sided open sipe connected to the main groove on one side, and the lug grooves are circumferentially offset for each block row. It is.
[0015]
(2) The pneumatic tire according to (1), wherein the central sipe of the three sipes is an open sipe connected to the main groove on both sides.
[0016]
(3) The pneumatic tire according to (1) or (2), wherein the sipe at both ends of the three sipes is a one-sided open sipe connected to the main groove on one side.
[0017]
(4) The pneumatic tire according to (3), wherein the sipes at both ends are connected to the main grooves on opposite sides, respectively.
[0018]
(5) The pneumatic tire according to any one of the above (1) to (4), wherein the sipe is formed by a linear flat blade or a bent blade having one or more bent portions. It is.
[0019]
(6) The pneumatic tire according to any one of (1) to (5), wherein the depth of the sipe is 50% or more of the depth of the main groove.
[0020]
(7) The pneumatic tire according to any one of the above (1) to (6), wherein the length of the one-sided open sipe is 50% or more of the block width.
[0021]
In the pneumatic tire of the present invention, the drainage performance is improved by combining the four circumferential main grooves and the three sipes including at least one one-side open sipes, and further shifting the phases of the lug grooves. In addition to improved performance, performance on ice and performance on snow, the durability and uneven wear resistance of the block have been balanced, making it possible to realize a pneumatic tire with a higher performance than ever before.
[0022]
As described above, in Patent Document 3, four circumferential main grooves are provided, a block defined by the width direction grooves is provided between each circumferential main groove, and the number of sipes provided in the block is three. Although the tire to be the present invention is described, the effect obtained by combining the conditions related to these circumferential main grooves and sipes and the offset of the one-side open sipes and the lug grooves according to the present invention is described in this document. No mention is made.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 shows a block pattern of a pneumatic tire according to a preferred embodiment of the present invention. As shown in the figure, the pneumatic tire of the present invention has, on a tread portion of a tread portion, a block 3 divided by four circumferential main grooves 1 and lug grooves 2 intersecting therewith. In addition, the block 3 shown in the drawing has one open sipe 4 connected to the main groove 1 on both sides and two one-side open sipes 5a and 5b connected to the main groove 1 on one side, for a total of three. Are formed in the width direction.
[0024]
As shown in the figure, by setting the number of circumferential main grooves to four, the negative ratio in the circumferential direction is increased as compared with the conventional case of three, and the drainage property is improved. %, And the wet performance after the middle stage of wear can be secured satisfactorily. In addition, the block sipe is made up of three, and at least one of the sipe is a single-sided open sipe, thereby increasing the edge component and increasing the block rigidity. As a result, both on-ice performance and uneven wear resistance can be highly compatible.
[0025]
With regard to the three sipes provided in the block 3, if at least one of the sipes is a single-sided open sipe, an effect of preventing a decrease in block durability and uneven wear resistance due to the use of three sipes can be obtained. However, preferably, as shown in the drawing, two sipe at both ends of the three sipees are one-side open sipes 5a and 5b connected to the main groove 1 on one side. In particular, as shown in the drawing, by forming the one-side open sipes 5a and 5b so as to be connected to the opposite main grooves 1, respectively, it is possible to appropriately adjust the rigidity of the block in the tire width direction. From the same viewpoint, it is preferable that the central sipe is an open sipe 4 connected to the main groove 1 on both sides.
[0026]
The shape of the sipe is not particularly limited. For example, the sipe is formed by a linear flat blade as shown, or is formed by a bent blade having one or more bent portions. It can be. FIG. 2 shows an example of a pneumatic tire in which the central open sipe 4 is formed by a bending blade while the other configurations remain the same.
[0027]
Further, it is preferable that the depth of each sipe is 50% or more of the depth of the circumferential main groove 1. If the sipe depth is less than 50% of the main groove depth, the edge effect becomes insufficient, and the desired performance on ice cannot be secured. Furthermore, it is preferable that the length L of the one-side open sipes 5a and 5b is 50% or more of the block width W. Even if the length L of the one-side open sipes 5a, 5b is less than 50% of the block width W, a sufficient edge effect cannot be obtained, and the performance on ice tends to be insufficient. If the length L of the one-side open sipes 5a, 5b is too long, the effect of preventing the block rigidity from decreasing cannot be obtained, which is not preferable. In addition, the round holes 6 formed at the ends of the one-side open sipes 5a and 5b shown in FIGS. 1 and 2 are provided so as not to form sharp edges in order to suppress cracks at the sipes end.
[0028]
Further, in the present invention, as shown in the figure, the lug grooves 2 are circumferentially offset for each block row, that is, the lug grooves 2 are all provided with a phase shift for each block row. Thereby, continuous snow column shearing during traveling on snow is enabled, and it is possible to more effectively improve on-snow performance. Note that the offset amount between the lug grooves 2 is not particularly limited as long as all the phases of the lug grooves can be shifted for each block row.
[0029]
In the tire of the present invention, the tread pattern formed on the tread portion of the tire only needs to satisfy the above conditions, and other conditions such as the size of each groove and the pitch of the block pattern are particularly limited. is not. Also, conditions such as the structure of the tire itself are not particularly limited.
[0030]
【Example】
Hereinafter, the present invention will be described using examples.
Conventional example As a conventional example, a pneumatic tire of size 11R22.5W980Z having a tread pattern shown in FIG. 3 was produced. In the illustrated tire, three circumferential main grooves 11 and 12 extending in the circumferential direction, a sub-groove 13 extending continuously in the circumferential direction between these main grooves, and a width direction are provided on the tread portion of the tread portion. Block rows 15, 16, 17 are defined by the width direction grooves 14 thus formed. One linear open sipe 18 is formed in each of the blocks 15, 16 and 17, and each of the blocks 15, 16 and 17 is shifted in phase between adjacent blocks. However, the block rows 15 and 17 have the same phase.
[0031]
As an example <br/> Example were produced pneumatic tire of the conventional example and the same size having a tread pattern shown in FIG. In the illustrated tire, four circumferential grooves 1 are provided, and a block 3 defined by these and a lug groove 2 has one open sipe 4 and two one-side open sipes 5a, 5b. Are formed in the width direction. Further, all of the lug grooves 2 are offset in the circumferential direction for each block row. Here, the depth of the open sipe 4 is 55% of the depth of the circumferential main groove 1, the depth of the one-side open sipe 5a, 5b is 55% of the depth of the circumferential main groove 1, and further, The length of one open sipe 5a, 5b was 70% or more of the block width.
[0032]
Each of the test tires of the conventional example and the example was subjected to the following tests. The test conditions are as follows. The obtained results are shown in the following Tables 1 to 3 as indices with the conventional example (the wet turning test is a new one) as 100. The higher the value, the better the result.
Vehicle: 2-D4
Rim size / air pressure: 7.50 / 900 kPa
Load: Regular load specified in JATMA standard
(1) Wet turning test place: test course road surface: concrete
[Table 1]

[0035]
(2) Ice brake test location: Test course Road surface: On ice [0036]
[Table 2]

[0037]
(3) Snow traction test location: Test course road surface: Snow
[Table 3]

[0039]
【The invention's effect】
As described above, according to the present invention, by improving the tread pattern, the number of sipes provided in the circumferential main groove and the block is optimized, and especially the performance on ice and snow until the middle wear period, It is possible to provide a high-performance pneumatic tire that is highly compatible with wet performance from the middle stage of wear to the time of crushing.
[Brief description of the drawings]
FIG. 1 is a developed plan view showing a block pattern of a pneumatic tire according to a preferred embodiment of the present invention.
FIG. 2 is a developed plan view showing a block pattern of a pneumatic tire according to another preferred embodiment of the present invention.
FIG. 3 is a developed plan view showing a block pattern of a conventional pneumatic tire.
[Explanation of symbols]
Reference Signs List 1 circumferential main groove 2 lug groove 3 block 4 open sipe 5a, 5b one side open sipe 6 round hole portion 11, 12 circumferential main groove 13 sub groove 14 width direction groove 15, 16, 17 block row 18 open sipe

Claims (7)

An air having an annular tread portion, a pair of sidewall portions disposed radially inward from both sides of the tread portion in the tire radial direction, and a bead portion extending radially inward of the sidewall portion in the tire radial direction. For entering tires,
On the tread portion of the tread portion, a block divided by four main grooves extending in the circumferential direction and a lug groove intersecting with the main groove is formed, and the block has three sipes in the width direction, A pneumatic tire, wherein at least one of the sipes is a one-sided open sipe connected to the main groove on one side, and the lug grooves are circumferentially offset for each block row. . The pneumatic tire according to claim 1, wherein a central sipe of the three sipe is an open sipe connected to the main groove on both sides. The pneumatic tire according to claim 1 or 2, wherein the sipe at both ends of the three sipees is a one-sided open sipe connected to the main groove on one side. The pneumatic tire according to claim 3, wherein the sipes at both ends are connected to the main grooves on opposite sides, respectively. The pneumatic tire according to any one of claims 1 to 4, wherein the sipe is formed of a straight flat blade or a bent blade having one or more bent portions. The pneumatic tire according to any one of claims 1 to 5, wherein the depths of the sipe are each 50% or more of the depth of the main groove. The pneumatic tire according to any one of claims 1 to 6, wherein the length of the one-side open sipe is 50% or more of the block width.

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