JP3606459B2 - Pneumatic tire - Google Patents

Description

表１の結果が示すように、実施例では横方向及び前後方向のエッジ成分が大きいため、アイス制動性能、アイス旋回性能及び耐摩耗性能が従来品と比較して大幅に改善されていた。これに対して、サイプの第２部分の長さが小さい比較例２では、アイス旋回性能の改善効果が殆どなかった。
【図面の簡単な説明】
【図１】本発明の空気入りタイヤの一例のトレッド面を示す平面図
【図２】図１のトレッド面のブロックを示す要部拡大図
【図３】本発明におけるサイプの他の例を示す要部拡大図
【符号の説明】
１ ブロック
１０ サイプ
１１ サイプの波状部分
１１ａ 第１部分
１１ｂ 第２部分
１２ 略直線部分
ＰＩ ピッチ
ＷＤ タイヤ幅方向
ＰＤ タイヤ周方向[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire including a tread pattern having a plurality of blocks in which a sipe including a wavy portion or a zigzag portion is formed, and is particularly useful as a studless tire.
[0002]
[Prior art]
Conventionally, in order to improve the ice performance of a studless tire, an example in which a large number of sipes are arranged in each part (center part, mediate part, shoulder part) of a tire pattern is known. For the purpose of improving the ice braking performance, many sipes extending in the tire width direction have been arranged to improve the edge effect in the front-rear direction. For the purpose of improving the ice turning performance, the sipe component having an angle approaching the tire circumferential direction has been increased to improve the lateral edge effect.
[0003]
As a method for improving both the ice braking performance and the ice turning performance, it has been generally performed to form a wave-shaped or zigzag-shaped sipe in the tire width direction instead of the straight sipe in the tire width direction. In such a wave-shaped sipe, in addition to a portion with an angle close to the tire width direction, there is a portion with an angle close to about 45 ° from the tire width direction. Can do.
[0004]
However, in the above-mentioned wave type sipe, etc., the decrease in the component in the tire width direction is unavoidable, and the component in the tire circumferential direction cannot be said to be sufficient at an angle of about 45 °. The improvement effects were not sufficient.
[0005]
[Problems to be solved by the invention]
On the other hand, in JP-A-2000-94909, the ratio of short side to long side (short side / long side) of the zigzag sipe extending in the tire width direction is set to 0.25 to 0.75, and the long side Proposed pneumatic tires with an inclination angle of 65 to 90 ° with respect to the tire circumferential direction, an intersection angle between the long side and the short side of 90 to 130 °, and an inclination direction of the lateral groove and the long side opposite to each other. Has been. And it is disclosed that ice braking performance, ice running stability, and edge wear resistance are improved by such sipe formation.
[0006]
However, the above sipe extends in the tire width direction, the length of the short side is small, and the angle also allows a large deviation from the tire circumferential direction. There seems to be little effect. And in the said gazette, the improvement effect of ice running stability is positioned as the effect by having made the inclination direction of a horizontal groove and the inclination direction of a sipe long side opposite.
[0007]
Therefore, an object of the present invention is to provide a pneumatic tire having large edge components in the lateral direction and the front-rear direction and having a large improvement effect on both ice braking performance and ice turning performance.
[0008]
[Means for Solving the Problems]
The above object can be achieved by the present invention as described below. That is, the present invention relates to a pneumatic tire having a tread pattern having a plurality of blocks each having a sipe including a wavy portion, wherein the sipe has a tangent of -20 to 20 ° with respect to the tire width direction. One portion and a second portion whose tangent is at an angle of -20 to 20 ° with respect to the tire circumferential direction, and the ratio of the lengths of both portions (first portion / second portion) is 0.9 to 1.1. And a wavy portion including a length of 40% or more in one cycle is repeatedly formed in the same cycle.
[0010]
Moreover, it is preferable that the sipe includes a substantially straight portion extending from at least one end of the wavy portion or the zigzag portion to the side wall of the block or the vicinity thereof and having an angle of -20 to 20 ° with respect to the tire width direction. .
[0011]
[Function and effect]
According to the present invention, since the tangent line includes the first portion having an angle of -20 to 20 ° with respect to the tire width direction with a length of 40% or more in one cycle of the sipe, the edge component in the front-rear direction increases. Front and rear performance such as ice braking performance is improved. In addition, since the tangent includes the second portion having an angle of -20 to 20 ° with respect to the tire circumferential direction with a length of 40% or more in one cycle of the sipe, the edge component in the lateral direction is increased, and the ice turning property is increased. Will improve. And both the ice braking performance and ice turning performance can be improved in a well-balanced manner by setting the ratio of the lengths of both portions (first portion / second portion) to 0.9 to 1.1. In addition, since the sipe component of about 45 ° with respect to the tire width direction is reduced, the block piece is difficult to open when a longitudinal force or a lateral force is generated, and the block piece is less likely to fall down. Step wear can also be made difficult to occur.
[0013]
The sipe extends from at least one end of the wavy portion or zigzag portion to the side wall of the block or the vicinity thereof, and when the direction includes a substantially straight portion having an angle of -20 to 20 ° with respect to the tire width direction, the side wall of the block Therefore, it is possible to prevent the block piece from being damaged near the sipe end.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing a tread surface of an example of the pneumatic tire of the present invention. 2A is an enlarged view of a main part showing a block of the tread surface of FIG. 1, and FIG. 2B is an enlarged view of a main part of the sipe.
[0015]
As shown in FIG. 1, the pneumatic tire of the present invention includes a tread pattern T having a plurality of blocks 1 each having a sipe 10 including a wavy portion or a zigzag portion. In the present embodiment, an example is shown in which rectangular blocks 1 are formed by being divided by circumferential grooves 2 and lateral grooves 3, and five rows of blocks 1 are arranged for the tire center CL. In this example, the sipes 10 in each block 1 are arranged so that the directions of the sipes 10 are opposite to each other, but they may be arranged in the same direction.
[0016]
In the sipe 10 according to the present invention, as shown in FIGS. 2A to 2B, the wavy portion 11 or the zigzag portion of the sipe 10 has a tangent of -20 to 20 ° with respect to the tire width direction WD. The first portion 11a is included in a length of 20 to 70% in one cycle, and the second portion 11b whose tangent is at an angle of -20 to 20 ° with respect to the tire circumferential direction PD is 20 to 70% in one cycle. It is characterized by including in length. FIG. 2B shows the sipe 10 that is contained in the length 42% of the first portion 11a and the length 42% of the second portion 11b in one period corresponding to the pitch PI. The tangent line of the sipe 10 is determined with reference to the sipe center line.
[0017]
In the present invention, while improving the balance between the ice braking performance and the ice turning performance, while maintaining the performance of both of them at a certain level or more, the length of the first portion 11a in one cycle is 40 to 60%, and the second portion 11b The length within one period is preferably 40 to 60%.
[0018]
The ratio of the length of the first portion 11a and the second portion 11b (first portion / second portion) is preferably 0.8 to 1.2, more preferably 0.9 to 1.1. is there. Most preferably, the wavy portion 11 of the sipe 10 is formed by making the ratio of the lengths of the first portion 11a and the second portion 11b substantially the same and repeating this in the same cycle.
[0019]
In the present invention, a zigzag portion may be provided instead of providing the wavy portion 11 as shown in FIG. 2, but in order to improve the wear resistance of the bent portion, the bent portion of the sipe 10 as shown in FIG. It is preferable that 11c has a circular arc part. Further, the bent portion need not be formed only by an arc, and may be an elliptical arc or a part of a parabola.
[0020]
On the other hand, as shown in FIG. 2A, the sipe 10 in the present embodiment extends from at least one end of the corrugated portion 11 to the side wall of the block or the vicinity thereof, and the direction is -20 to 20 ° with respect to the tire width direction WD. And a substantially straight portion 12 having an angle of.
[0021]
Moreover, the several sipe 10 is made into the one-side obstruction | occlusion sipe, the obstruction | occlusion side is arrange | positioned alternately right and left, and the release side and obstruction | occlusion side of the sipe 10 are made to alternate in a block side wall. Thus, by maintaining the block rigidity in the vicinity of the block side wall, uneven wear at that portion is effectively prevented.
[0022]
In the example shown in FIG. 2, eight sipes 10 are arranged for each block 1. However, in the present invention, it is preferable to arrange a plurality of sipes 10 for each block 1. Thus, the sipe density can be increased by increasing the number of the sipe 10, but the sipe density is preferably 0.1 mm / mm ² or more.
[0023]
The plurality of sipes 10 are preferably arranged such that the wavy portions 11 or zigzag portions thereof are substantially parallel to each other. Furthermore, it is preferable to synchronize the periods of adjacent sipes 10.
[0024]
The sipe depth is preferably about 1 to 8 mm, and the sipe groove width is preferably about 0.1 to 0.5 mm.
[0025]
The pneumatic tire of the present invention is the same as a normal pneumatic tire except that it includes the tread pattern T as described above, and any conventionally known material, shape, structure, manufacturing method, and the like can be employed in the present invention.
[0026]
The pneumatic tire of the present invention can be applied to so-called summer tires, but is particularly useful as a studless tire because it exhibits the effects as described above.
[0027]
[Other Embodiments]
Hereinafter, other embodiments of the present invention will be described.
[0028]
(1) In the above-described embodiment, an example is shown in which the sipe 10 shown in FIGS. 1 to 2 is formed, but the sipe in the present invention is as shown in FIGS. 3 (a) to 3 (c), for example. But you can.
[0029]
The sipe 10 shown in FIG. 3 (a) is an example in which the sipe 10 is formed only by the undulating portion 11 without providing a substantially straight portion having an angle of −20 to 20 ° with respect to the tire width direction extending from the undulating portion 11. is there. Even in this case, it is preferable that the end of the wavy portion 11 is at an angle of -20 to 20 ° with respect to the block side wall. To achieve this, the periodicity of the end of the wavy portion 11 is slightly changed. It may be changed.
[0030]
The sipe 10 shown in FIG. 3B is obtained by slightly tilting the whole with respect to that shown in FIG. As a result, the direction of the substantially straight portion 12 extending from at least one end of the wavy portion 11 or the zigzag portion to the side wall of the block or the vicinity thereof is substantially 0 ° with respect to the tire width direction.
[0031]
A sipe 10 shown in FIG. 3C is formed by forming a sipe including a wave-like portion 11 or a zigzag-like portion close to a square wave. Even in the sipe 10 having such a shape, the tangent includes a first portion having an angle of -20 to 20 ° with respect to the tire width direction in a length of 20 to 70% in one cycle, and the tangent is in the tire circumferential direction. On the other hand, the second portion having an angle of -20 to 20 ° can be included in a period of 20 to 70%.
[0032]
(2) In the above-described embodiment, an example is shown in which the sipe shape does not change in the depth direction. However, a concave portion and a convex portion that engage with each other may be formed on the sipe inner surface facing each other. In that case, examples of the shape of the concave portion and the convex portion include hemispherical, conical, or pyramidal irregularities.
[0033]
(3) In the above-described embodiment, an example in which the sipe reference plane is formed so as to be perpendicular to the block surface is shown. ° or less) may be inclined.
[0034]
(4) In the above-described embodiment, an example of the block pattern as shown in FIG. 1 is shown. However, the block pattern is not limited to a rectangular block, and may be a parallelogram, V-shaped, pentagonal, or curved block. In addition, a grooved block or a part of land portion may be continuous in the circumferential direction near the center or near the end.
[0035]
【Example】
Examples and the like specifically showing the configuration and effects of the present invention will be described below. In addition, each performance evaluation of the tire was performed as follows.
[0036]
(1) Ice braking performance tires were mounted on a real vehicle (domestic 2000cc class FF sedan), and the vehicle was fully frozen by applying braking force at a speed of 40km / h while running on a frozen road under the load conditions of one passenger. The braking distance was evaluated with an index. In addition, evaluation is shown by an index display when the conventional product (Comparative Example 1) is set to 100, and a larger value indicates a better result.
[0037]
(2) Ice turning performance tires are mounted on the same actual vehicle as above, running on the same road surface under the load conditions of one person riding on the Lemnis skating curve (eight curve: R = 25m yen), and the lap time is evaluated as an index did. In addition, evaluation is shown by an index display when the conventional product (Comparative Example 1) is set to 100, and a larger value indicates a better result.
[0038]
(3) Abrasion resistance performance The amount of step wear when traveling on a paved road for 8000 km (step difference between block pieces on both sides of the sipe due to wear) was measured and evaluated by an index. In addition, evaluation is shown by an index display when the conventional product (Comparative Example 1) is set to 100, and a larger value indicates a better result.
[0039]
Examples 1-3
In the tread pattern as shown in FIG. 1, a sipe having a depth of 7 mm, a width of 0.3 mm, a wavy portion period of 2.5 mm, and an amplitude of 2.25 mm is formed under the conditions shown in Table 1, and a radial of size 185 / 70R14. A tire was manufactured and each performance evaluation was performed. The results are shown in Table 1. In addition, the sipe of Example 3 respond | corresponds to Fig.3 (a).
[0040]
Comparative example 1 (conventional product)
In the tread pattern as shown in FIG. 1, a conventional corrugated sipe extending mainly in the tire width direction (mainly an inclined portion of about 45 ° with respect to the tire width direction) is formed to produce a radial tire of size 185 / 70R14. Each of the above performance evaluations was performed. The results are shown in Table 1.
[0041]
Comparative Example 2
In Example 1, a radial tire of size 185 / 70R14 was manufactured in the same manner as in Example 1 except that the length of the second part of the sipe was changed as shown in Table 1, and the above performance evaluations were performed. went. The results are shown in Table 1.
[0042]
[Table 1]

As shown in the results of Table 1, in the examples, the edge components in the lateral direction and the front-rear direction are large, so that the ice braking performance, the ice turning performance, and the wear resistance performance are greatly improved as compared with the conventional product. On the other hand, in Comparative Example 2 in which the length of the second part of the sipe was small, there was almost no effect of improving the ice turning performance.
[Brief description of the drawings]
FIG. 1 is a plan view showing a tread surface of an example of a pneumatic tire of the present invention. FIG. 2 is an enlarged view of a main part showing a block of the tread surface of FIG. 1. FIG. 3 shows another example of a sipe in the present invention. Enlarged view of main parts [Explanation of symbols]
1 block 10 sipe 11 sipe wavy portion 11a first portion 11b second portion 12 substantially straight portion PI pitch WD tire width direction PD tire circumferential direction

Claims (2)

In a pneumatic tire provided with a tread pattern having a plurality of blocks formed with sipes including wavy portions,
The sipe includes a first portion having a tangent angle of -20 to 20 ° with respect to the tire width direction and a second portion having a tangent angle of -20 to 20 ° with respect to the tire circumferential direction. Repeating the wavy portions including the length ratio (first portion / second portion) of 0.9 to 1.1 with a length of 40% or more in one cycle in the same cycle A pneumatic tire characterized by being formed. 2. The pneumatic tire according to claim 1, wherein the sipe extends from at least one end of the wavy portion to a side wall of the block or the vicinity thereof, and includes a substantially straight portion whose direction is -20 to 20 ° with respect to the tire width direction.

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