JP4281901B2 - Pneumatic tire - Google Patents

Description

【００１７】
【発明の効果】
以上の通り、本発明の空気入りタイヤにおいて、ブロックをタイヤ周方向に略二分割する副スリットが刻まれ、前記副スリットのタイヤ周方向両側に波形サイプ、前記副スリットの底部に直線サイプがそれぞれ刻まれ、前記副スリットの幅及び深さを所定の寸法としたので、ドライ性能を維持し、スノー性能を向上でき、しかもチャンキングを防止することができる。
【図面の簡単な説明】
【図１】 本発明に係る空気入りタイヤのトレッドパターン概略展開図である。
【図２】 ブロックを概念的に示す斜視図である。
【図３】 １ブロックにおけるスリット及びサイプバリエーションを示す図である。
図３(a)は副スリット４、直線サイプ５ともにオープンの基本形である。
図３(b)は直線サイプ５の片側がクローズドである。
図３(c)は副スリット４の両側がクローズドである。
図３(d)は直線サイプ５の両側がクローズドである。
図３(e)は副スリット４の片側がクローズドである。
図３(f)は直線サイプ５が副スリット４中央部で片側クローズドである。
図３(g)は直線サイプ５が副スリット４中央部と両端でクローズドである。
【図４】 従来例に係る空気入りタイヤのトレッドパターン概略展開図である。
【符号の説明】
１ 主溝
２ 主スリット
３ ブロック
４ 副スリット
５ 直線サイプ
６ 波形サイプ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire in which a corrugated sipe is engraved on a block, and relates to compatibility between dry performance and snow performance and prevention of chunking.
[0002]
[Prior art]
Conventionally, in order to improve the snow performance of a tire, the sipe edge effect has been used by carving a large number of sipes on the tread surface. On the other hand, in order to obtain satisfactory performance on a dry road surface, the block should have a higher rigidity. In order to achieve both of these performances, measures have been taken to limit the movement of the sipe (rocking effect) and increase the rigidity of the block by making the sipe shape into a waveform. For example, a pneumatic tire described in Patent Document 1 is known as a pneumatic tire engraved with corrugated sipes.
[0003]
[Patent Document 1]
JP-A-10-114205 (pages 3-4, FIGS. 3-4).
[0004]
[Problems to be solved by the invention]
However, in such a pneumatic tire, the rigidity of the central portion of the block is high, and on the other hand, the rigidity of the block end portion is low, so that the ground contact area is reduced and sufficient traction may not be obtained. As a method for solving these conflicting characteristics, a method of deepening the sipe at the center of the block and conversely shallowing the sipe at the block end can be considered. However, in such a method, since the sipe has a waveform, the stress due to the deformation of the block concentrates on the peak portion of the wave at the bottom of the sipe, and the chunk may be broken.
[0005]
Accordingly, an object of the present invention is to maintain dry performance, improve snow performance, and prevent chunking.
[0006]
[Means for Solving the Problems]
As a result of diligent studies to solve the above problems, in the present invention, in a pneumatic tire including a block defined by a main groove and a main slit that communicates between the main grooves on the tread surface,
Sub-slits that divide the block substantially in the tire circumferential direction are engraved, corrugated sipes are engraved on both sides of the sub-slit in the tire circumferential direction, and linear sipes are engraved on the bottom of the sub-slits, and the width of the sub-slit is the block A pneumatic tire having a width of 40% to 60% of the width of the main slit that divides the block and a depth of the sub slit of 40% to 60% of the depth of the main slit that divides the block. .
[0007]
By engraving the sub-slit that divides the block substantially in the tire circumferential direction, the circumferential rigidity of the central portion of the block is lowered, and it becomes easy to fall down, so that the traction on the snow road surface increases. In addition, since the width and depth of the sub slit are 40% to 60% of the width and depth of the main slit that defines the block, the rigidity is not significantly reduced and the performance on the dry road surface is maintained. .
[0008]
In addition, since a straight sipe is engraved on the bottom of the secondary slit, even if there is a deformation due to falling down, the stress is distributed to the bottom of the secondary slit and the bottom of the linear sipe, and the stress is concentrated on the top of the wave. Unlike the above, stress is not concentrated in one place, so chunking can be prevented.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a pneumatic tire according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic development view of a tread pattern of a pneumatic tire according to the present invention. A main groove 1 extending in a tire circumferential direction R is formed on a surface of a tread T, and a main slit 2 communicating the main grooves 1 with each other. The block 3 is defined by the main groove 1 and the main slit 2. A sub-slit 4 is engraved so as to be divided into two substantially in the tire circumferential direction R of the block 3, and a straight sipe 5 is engraved on the bottom 4 a of the slit 4. Waveform sipes 6 are carved on both sides of the tire circumferential direction R of the slit 4.
[0010]
FIG. 2 is a perspective view conceptually showing the block for explanation, and the shape does not coincide with the block of FIG. The sub slit 4 that substantially bisects the block 3 in the tire circumferential direction R reduces the circumferential rigidity of the central portion of the block 3 and makes it easy to fall down. As a result, the traction on the snow road surface increases.
[0011]
Even if the block 3 is deformed due to the falling, the stress is distributed to the bottom 4 a of the sub slit 4 and the bottom 5 a of the straight sipe 5. In addition, unlike the waveform sipe 6 in which stress concentrates on the wave top 6a, the stress is not concentrated in one place, so that chunking can be prevented.
[0012]
The width W and depth D of the sub slit 4 are preferably 40% to 60% of the width and depth of the main slit 2 that partitions the block 3, respectively. If it is less than 40%, the rigidity is still high and traction cannot be increased. On the other hand, if it exceeds 60%, the rigidity is excessively lowered and the performance on the dry road surface is lowered.
[0013]
The depth of the sipe 5 is not required to be deeper than the main slit 2. In addition to the illustrated two opens, one open or both closed may be used, or two or more parts may be divided and carved. Further, the number of waveform sipes 6 may be not limited to one on one side of the slit 4 but may be plural. Further, the sub slit 4 may be a single open or a double closed in addition to the both open shown. FIG. 3 shows variations of the sub slit 4, the straight sipe 5, and the corrugated 6 sipe carved in these blocks 3. FIG. 3 (a) shows the open basic shape for both the secondary slit 4 and the straight sipe 5. In FIG. 3B, one side of the straight sipe 5 is closed. In FIG. 3C, both sides of the sub slit 4 are closed. In FIG. 3D, both sides of the straight sipe 5 are closed. In FIG. 3 (e), one side of the sub slit 4 is closed. In FIG. 3 (f), the straight sipe 5 is closed on one side at the center of the sub slit 4. In FIG. 3 (g), the straight sipe 5 is closed at the center and both ends of the sub slit 4. The block shape may be a wedge-shaped block shape in addition to the substantially parallelogram shown in the figure.
[0014]
【Example】
As an embodiment of the pneumatic tire according to the present invention, a tire having the tread pattern shown in FIG. 1 and a block shape as shown in FIG. 4 as a conventional example is the same as the embodiment, and does not include a secondary slit and a straight sipe. Tires having a secondary slit as comparative examples 1 to 3 but having a width and depth outside the range, and tires having a secondary slit as comparative example 4 but not having a straight sipe were each prototyped and used as a rear-wheel drive passenger car. Wearing and performance evaluation were performed. The dimensions of the main slit, the sub slit, and the sipe are as shown in Table 1, and all tire sizes were 195 / 65R15.
[0015]
The evaluation results are as shown in Table 1. The dry steering performance indicates the reciprocal of the lap time on the handling course (dry road), and the snow braking performance indicates the reciprocal of the stop distance from 40 km / h on the snow road surface. . Therefore, the larger the number, the better the performance. The chunking test was performed in accordance with the high-speed performance test A of JIS standard D4230. A load of 472 kg is applied to a tire with an internal pressure of 280 kPa on a bench test machine, and first accelerates to an initial speed of 170 km / h in the first 10 minutes, then accelerates by 10 km / h every 10 minutes, up to a maximum of 230 km / h An 8-step test was performed. The presence / absence of chunking described in Table 1 is the result of visually confirming the occurrence of chunking in the tire after completion of the test.
[0016]
[Table 1]

[0017]
【The invention's effect】
As described above, in the pneumatic tire of the present invention, sub-slits that divide the block into two substantially in the tire circumferential direction are engraved, corrugated sipes on both sides of the sub-slit in the tire circumferential direction, and linear sipes on the bottom of the sub-slits, respectively. Since the width and depth of the sub-slit are set to predetermined dimensions, dry performance can be maintained, snow performance can be improved, and chunking can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic development view of a tread pattern of a pneumatic tire according to the present invention.
FIG. 2 is a perspective view conceptually showing a block.
FIG. 3 is a diagram showing slits and sipe variations in one block.
FIG. 3 (a) shows the open basic shape for both the secondary slit 4 and the straight sipe 5.
In FIG. 3B, one side of the straight sipe 5 is closed.
In FIG. 3C, both sides of the sub slit 4 are closed.
In FIG. 3D, both sides of the straight sipe 5 are closed.
In FIG. 3 (e), one side of the sub slit 4 is closed.
In FIG. 3 (f), the straight sipe 5 is closed on one side at the center of the sub slit 4.
In FIG. 3 (g), the straight sipe 5 is closed at the center and both ends of the sub slit 4.
FIG. 4 is a schematic development view of a tread pattern of a pneumatic tire according to a conventional example.
[Explanation of symbols]
1 Main groove 2 Main slit 3 Block 4 Sub slit 5 Linear sipe 6 Waveform sipe

Claims (1)

In a pneumatic tire provided with a block defined by a main slit and a main slit communicating the main grooves with each other on the tread surface,
Sub-slits that divide the block substantially in the tire circumferential direction are engraved, corrugated sipes are engraved on both sides of the sub-slit in the tire circumferential direction, and linear sipes are engraved on the bottom of the sub-slits, and the width of the sub-slit is the block A pneumatic tire having a width of 40% to 60% of the width of the main slit defining the block and a depth of the sub slit being 40% to 60% of the depth of the main slit defining the block.

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