JP2004338628A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further improve dry gripping performance, hydro-planing resistance performance and wear resistant performance. <P>SOLUTION: The groove area ratio L in the entire tread surface is set to 0.15 to 0.35 and the groove area ratio Li in the inner tread half section Si is set to be larger by 0.05 or more than the groove area ratio Lo in the outer tread half section So. A linear and peripheral direction main groove 10 with its tilting angle α to the groove wall surface being 30 to 50° is provided in the area Y away from the tire equator C by the distance of 20 to 55% of the tread half width TW/2 in the inner tread half section Si.In the outer tread half section So, outer tilting lateral main grooves 20 having lateral groove main sections 21 extending at a tilting angle β of 35° or more toward the tread edge Eo from the tire equator C is provided, without forming a peripheral groove. The lateral groove main sections 21 are connected to an inner communication sections 22i communicating with the peripheral direction main groove 10 or to an outer communication section 22o communicating with the tread edge E. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００４４】
実施例のタイヤは、ウエットグリップ性能とドライグリップ性能との双方を両立した高めうるのが確認できる。
【００４５】
【発明の効果】
本発明は叙上の如く構成しているため、優れた排水性を確保しながらパターン剛性を適正に高めることができ、ドライグリップ性能、耐ハイドロプレーニング性能、及び耐摩耗性能を向上できる。
【図面の簡単な説明】
【図１】本発明の空気入りタイヤの一実施例を示す断面図である。
【図２】そのトレッドパターンを示す展開図である。
【図３】周方向主溝の横断面図である。
【図４】（Ａ）、（Ｂ）は、周方向主溝の溝壁面の傾斜角度を説明する線図である。
【図５】外のトレッド半部分から排除する周方向溝の一例を示す線図である。
【図６】本発明で用いるトレッドパターンの他の実施例を示す展開図である。
【図７】（Ａ）、（Ｂ）は、従来タイヤのトレッドパターンの一例を示す展開図である。
【符号の説明】
２Ｓ トレッド面
１０ 周方向主溝
２０ 外の傾斜横主溝
２０Ａ 第１の外の傾斜横主溝
２０Ｂ 第２の外の傾斜横主溝
２１ 横溝主部
２２ｉ 内の連通部
２２ｏ 外の連通部
Ｃ タイヤ赤道
Ｅ、Ｅｉ、Ｅｏ トレッド端
ｇ 溝壁面
Ｓｉ 内のトレッド半部分
Ｓｏ 外のトレッド半部分[0001]
TECHNICAL FIELD OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention can exhibit high dry grip performance and abrasion resistance when racing, for example, in a circuit competition or gymkhana competition, while sufficiently ensuring excellent wet grip performance (hydroplaning resistance performance) particularly on public roads. Related to pneumatic tires.
[0002]
2. Description of the Related Art
As shown in FIG. 7A, an S-shaped tread pattern mainly for improving dry grip performance as a tread pattern of a high-performance tire premised on race driving such as circuit competition and gym khana competition in addition to traveling on public roads. As illustrated in FIG. 7B, a V-shaped pattern in which both wet grip performance and dry grip performance are improved is widely used (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-2000-127715 (FIGS. 2 and 8)
[0004]
However, the S-shaped pattern has a high pattern rigidity with respect to the lateral acceleration (lateral G), and thus has excellent dry grip performance (particularly, lateral grip performance), but has a small angle θ of the tread groove a with respect to the tire circumferential direction. At P1, wear tends to progress quickly. In addition, the angle θ is largely inclined at 35 ° or more in most of the tread groove a, and the hydroplaning resistance is not good.
[0005]
On the other hand, the V-shaped pattern has a good wet grip performance, but when racing on a road surface having a high coefficient of friction μ, for example, a race course at a high lateral acceleration (lateral G), the vehicle has an outer side. The lateral stiffness of the outer tread half part to is not high, and it is difficult to further reduce the running time even by changing the composition and structure of the tread rubber. Further, in the tread groove a disposed in the outer tread half portion to, there is a problem that wear is accelerated in a portion P2 where the angle θ is 35 ° or less.
[0006]
Therefore, the present invention provides a pneumatic tire that can appropriately increase the pattern rigidity while securing excellent drainage performance, and can further improve dry grip performance, wet grip performance, and wear resistance performance. The purpose is.
[0007]
[Means for Solving the Problems]
In order to achieve the object, the invention of claim 1 of the present application is a pneumatic tire provided with an asymmetric pattern in which a tread pattern is different on both sides of a tire equator on a tread surface,
The tread surface is centered on the tire equator, and when the tire is mounted on the vehicle, the tread half portion on the inside of the vehicle and the outer tread half portion on the outside of the vehicle are virtually divided, and the inner tread half portion is The groove area ratio Li of the tread pattern is 0.05 or more larger than the groove area ratio Lo of the tread pattern in the outer half of the tread outside the vehicle, and the groove area ratio L of the tread pattern on the entire tread surface is 0.15. ~ 0.35,
The inner tread half portion has a linear circumferential main groove extending continuously in the tire circumferential direction in a region Y separated from the tire equator by a distance of 20 to 55% of a tread half width from the tire equator to the tread edge. And the inclination angle α of the groove wall surface of the circumferential main groove with respect to the normal to the tread surface is set to 30 to 50 °,
In the outer tread half, without providing a circumferential groove extending continuously in the tire circumferential direction,
Moreover, the outer half of the tread extends from the inner end to the tire equator toward the tread end and has an outer inclined lateral main groove having an inclined angle β of 35 ° or more with respect to the tire circumferential direction. Yes,
And the outer inclined horizontal main groove is connected to the inner end of the horizontal groove main portion and communicates with the circumferential main groove beyond the tire equator, or the outer end of the horizontal groove main portion and the tread end. , And the inclination angle β at the communication position of each communication portion is set to 75 to 90 °.
[0008]
According to a second aspect of the present invention, the outer inclined horizontal main groove comprises only a first outer inclined horizontal main groove in which an outer communicating portion is connected to the horizontal groove main portion.
[0009]
In the invention of claim 3, the outer inclined horizontal main groove includes a first outer inclined horizontal main groove having an outer communicating portion connected to the lateral groove main portion, and the inner communicating portion having a lateral groove main portion. And a second outer inclined horizontal main groove connected thereto.
[0010]
Further, in the invention according to claim 4, the outer inclined horizontal main groove is such that the first outer inclined horizontal main groove and the second outer inclined horizontal main groove are alternately arranged in a circumferential direction. Features.
[0011]
Further, in the invention of claim 5, the tread surface has a radial distance Hi from the tire equatorial point at the tread end of the inner tread half and a radial distance from the tire equatorial point at the tread end of the outer tread half. The ratio Hi / Ho to the distance Ho is set to 1.02 to 1.20.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to illustrated examples. FIG. 1 shows a meridional section of the pneumatic tire of the present invention, and FIG. 2 shows its tread pattern.
In FIG. 1, a pneumatic tire 1 is a high-performance tire premised on both running on a public road and running in a race such as a circuit competition and a gym khana competition. 4 has a radially structured carcass 6 leading to a bead core 5.
[0013]
A belt layer 7 is wound around the outside of the carcass 6 and inside the tread portion 2, and the flatness H / W, which is the ratio of the tire cross-sectional height H to the tire width W, is determined by the tagging effect. In the present example, it is restricted to 50% or less, for example, 40%. Thereby, while increasing the tire rigidity, the tread width TW is increased, and the high-speed performance and the steering stability are improved.
[0014]
Here, the “tread width TW” is a tire axial distance between the tread ends E, E, and the “tread end E” is a virtual line that extends the contour of the tread surface 2S outward in the axial direction. When an intersection with a virtual line extending outwardly in the radial direction from the contour of the buttress surface 3S is defined as J, a radial line passing through the intersection J intersects the tire surface.
[0015]
Then, in the pneumatic tire 1 of the present invention, the tread surface 2S is, with the tire equator C as a center, the inner tread half Si that is inside the vehicle and the outer tread half So that is outside the vehicle when the vehicle is mounted. When the tread pattern is virtually divided into two, the tread pattern of the inner tread half Si and the tread pattern of the outer tread half So are formed in an asymmetric pattern different from each other.
[0016]
Specifically, as shown in FIG. 2, the tread half portion Si in the region Y is separated from the tire equator C by a distance of 20 to 55% of the tread half width TW / 2 (１ ／ of the tread width TW). A single circumferential main groove 10 extending continuously in the circumferential direction of the tire is provided.
[0017]
The circumferential main groove 10 is a straight groove having a high drainage effect with a groove width GW0 of 14 mm or more, preferably 18 mm, and the groove center line is arranged in the region Y, that is, the tire equator at the groove center line. The distance L0 from C is set to 20 to 55% of the half width TW / 2 of the tread.
[0018]
If the circumferential main groove 10 is arranged on the outside of the vehicle with respect to the area Y, the pattern rigidity in the outer tread half portion So cannot be sufficiently ensured, so that the high dry grip performance and the high durability required for racing. It becomes difficult to satisfy wear performance at a high level. Conversely, when the circumferential main groove 10 is disposed on the inner side of the vehicle with respect to the area Y, the wet grip performance required for traveling on a public road cannot be sufficiently secured.
[0019]
Further, from the viewpoint of dry grip performance and abrasion resistance, the circumferential main groove 10 has, as shown in FIG. 3, a tread surface in which a groove wall surface g is formed by a groove side edge in a groove cross section perpendicular to the groove center line. It is necessary to incline at a large inclination angle α of 30 to 50 ° with respect to the normal to 2S. In particular, when turning, a larger lateral force acts on the outside of the vehicle than on the inside of the vehicle. It is preferable to set the value larger than (αo> αi). If the inclination angle α is less than 30 °, the rigidity in the vicinity of the groove side edge becomes insufficient, resulting in reduced wear resistance such as uneven wear such as track wear. Conversely, if the inclination angle α exceeds 50 °, the groove volume decreases and the drainage property decreases.
[0020]
In addition, as shown in FIG. 4 (A), when the groove wall surface g is a convexly curved surface, the inclination angle α of the tangent at each position of the curved surface is in the range of 30 to 50 °, and FIG. ), When the groove wall surface g is a curved surface composed of a plurality of surface portions, the inclination angle α of each surface portion is in the range of 30 to 50 °. When comparing the inclination angles αi and αo, in the case of a curved surface, the average of the maximum value and the minimum value of the inclination angle α of the tangent is compared. Compare by value.
[0021]
Further, the inner tread half portion Si may be provided with an inner inclined horizontal main groove 11 between the circumferential main groove 10 and the inner tread end Ei. In this example, the inclined horizontal main groove 11 has an inner end communicating with the circumferential main groove 10 and an outer end separated from the inner tread end Ei by a distance L1 in the tire axial direction. Is formed including the inclined horizontal main groove 11A.
[0022]
In particular, in this example, the inner inclined horizontal main groove 11 communicates with the first inner inclined horizontal main groove 11A, the outer end communicates with the inner tread end Ei, and the inner end extends from the circumferential main groove 10 to the tire shaft. A case is illustrated in which it is formed from a second inner slanted horizontal main groove 11B interrupted by a distance L2 in the direction. At this time, it is preferable from the viewpoint of uniformity that the first and second inclined horizontal main grooves 11A and 11B are alternately arranged in the circumferential direction.
[0023]
Note that the distances L1 and L2 are preferably 7% to 14% of the tread width TW. If the distance L1 and L2 are less than 7%, the rigidity is reduced and the dry grip performance and wear resistance tend to decrease. Conversely, if it exceeds 14%, the wet grip performance tends to decrease. In addition, for wet grip performance, it is preferable that the first and second inclined horizontal main grooves 11A and 11B have an overlapping portion 12 that overlaps each other in the tire circumferential direction.
[0024]
Further, the inclination angle γ of the inner inclined horizontal main groove 11 with respect to the circumferential direction is preferably 35 ° or more, and particularly at the communication position with the circumferential main groove 10 and the inner tread end Ei. It is desirable that the inclination angle γ1 be 75 to 90 °. Thereby, an excessive decrease in rigidity at the communication position can be suppressed, and a decrease in wear resistance can be suppressed.
[0025]
On the other hand, a higher lateral rigidity is required on the outer half tread So, because a larger lateral force acts on the outer tread half during turning. For this purpose, as shown in FIG. 2, the outer tread half portion So is not provided with a circumferential groove extending continuously in the tire circumferential direction, and the outer inclined main groove 20 is inclined and extends in the tire circumferential direction. Is formed.
[0026]
Here, "do not provide a circumferential groove extending continuously in the tire circumferential direction" means to eliminate all circumferential grooves that cause a decrease in pattern lateral rigidity. Main grooves with a groove width of 3 mm or more, with a main purpose of optimizing drainage and pattern rigidity, narrow grooves with a groove width of 1.0 to 3 mm, and main purposes of optimizing pattern rigidity and edge effects Siping with a groove width of less than 1.0 mm is targeted. Further, as schematically shown in FIG. 5, a connecting groove 30 </ b> A or the like that sequentially connects the outer inclined main grooves 20 adjacent to each other in the tire circumferential direction can be regarded as one zigzag circumferential groove 30. , Subject to exclusion.
[0027]
The outer inclined lateral main groove 20 has an inclination angle β of 35 ° or more with respect to the tire circumferential direction, and extends from the inner end 21Ei on the tire equator C toward the outer tread end Eo. The main portion of the lateral groove 21 is provided with a communication portion 22i which is continuous with the inner end 21Ei and communicates with the circumferential main groove 10 beyond the tire equator C, or the main portion of the lateral groove 21. An outer communication portion 22o is provided to communicate with the outer end 21Eo and communicate with the outer tread end Eo.
[0028]
In the present example, the outer inclined horizontal main groove 20 is connected to the first outer inclined main groove 20A in which the outer communicating main part 21 is connected to the outer communicating main part 21 and the first outer inclined horizontal main groove 20A. In this case, a case is shown in which the second main portion 20i is connected to a second outer inclined main groove 20B to which the portion 22i is connected. At this time, it is preferable from the viewpoint of uniformity that the first and second outer inclined main grooves 20A and 20B are alternately arranged in the circumferential direction. As required, the first outer inclined main groove 20 </ b> A extends beyond the tire equator C from the inner end 21 </ b> Ei of the main main portion 21 and is separated from the circumferential main groove 10 by a distance L <b> 3 in the tire axial direction. An edge 24 (shown by a dashed line) can also be provided.
[0029]
Here, in the outer inclined horizontal main groove 20, the inclination angle β needs to be 35 ° or more, and if it is less than 35 °, the pattern lateral rigidity against the lateral force during turning becomes insufficient. As a result, the dry grip performance (especially the lateral grip performance) during the race running is insufficient, so that the running time cannot be improved, and the wear resistance near the groove side edge of the outer inclined main groove 20 is reduced. .
[0030]
In particular, the outer inclined lateral main groove 20 tends to have reduced rigidity at the communication position with the outer tread end Eo and the circumferential main groove 10, thereby deteriorating wear resistance. Therefore, it is also important to set the inclination angle β1 at the communication position of each of the communication portions 22i and 22o in the range of 75 to 90 °, respectively, and to suppress a decrease in rigidity.
[0031]
When the inner and outer slanted horizontal main grooves 11 and 20 are curved, the slant angles β and γ are indicated by the slant angles of their tangents.
[0032]
Further, the distance L4 between the outer end and the outer tread end Eo of the second outer inclined main groove 20B is preferably set to 10% to 20% of the tread width TW. It tends to reduce dry grip performance and abrasion resistance. Conversely, if it exceeds 20%, the wet grip performance tends to decrease. In the case where the edge portion 24 is provided in the first outer inclined main groove 20A, it is necessary to secure the distance L3 to the circumferential main groove 10 at 12% or more of the tread width TW to improve the dry grip performance. It is preferable for ensuring abrasion resistance.
[0033]
Next, in the pneumatic tire 1 of the present invention, the groove area ratio L of the tread pattern in the entire tread surface 2S is set in the range of 0.15 to 0.35, and the pattern rigidity is increased in the outer tread half portion So. In order to obtain a larger lateral grip, the groove area ratio Lo of the tread pattern is 0.05 or more smaller than the groove area ratio Li of the tread pattern in the inner tread half Si (Li−Lo ≧ 0.05). ). The groove area ratio means the ratio of the opening area of the tread groove to the tread surface.
[0034]
When the groove area ratio L is less than 0.15, it is difficult to secure necessary wet grip performance, and the groove area ratio L is larger than 0.35, and the difference Li-Lo of the groove area ratio is less than 0.05. Then, it becomes difficult to satisfy a high level of high dry grip performance and abrasion resistance performance required for racing. From the viewpoint of wet grip performance, the difference Li-Lo in the groove area ratio is preferably 0.12 or less.
[0035]
The inner and outer inclined horizontal main grooves 11 and 20 are main grooves for drainage whose groove widths GW1 and GW2 are each 3 mm or more, and the upper limit of each groove width GW0, GW1, and GW2, and And the pitch of the outer inclined horizontal main grooves 11 and 20 are appropriately set according to the above-described groove area ratio L and the difference Li-Lo of the groove area ratio.
[0036]
Next, in the pneumatic tire 1 of the present invention, as shown in FIG. 1, the tire equator point CO of the inner tread end Ei is used in order to sufficiently utilize the excellent lateral grip property and greatly improve the turning performance. Has an asymmetrical tread profile in which the ratio Hi / Ho of the radial distance Hi from the tire to the radial distance Ho of the outer tread end Eo from the tire equatorial point CO is 1.02 to 1.20. I have.
[0037]
In the tire mounted on the turning center side of the turning vehicle, the ground contact center is on the inner tread half Si side, and in the evening ear mounted on the opposite side to the turning center, the ground contact center is on the outer tread half So. Side. At this time, by setting the ratio Hi / Ho to 1.02 to 1.20, the actual rolling radius of the evening ear on the turning center side, that is, the actual rolling radius on the inner tread half Si side is turned. It can be smaller than the actual rolling radius of the evening ear on the side opposite to the center, that is, the actual rolling radius on the side of the outer tread half So, and smooth turning is possible. When the ratio Hi / Ho is less than 1.02, the above effect is not exhibited. On the other hand, when the ratio exceeds 1.20, the straight running performance is impaired, and the contact pressure distribution becomes non-uniform and the wear performance tends to deteriorate. Become.
[0038]
FIG. 6 illustrates another embodiment of the tread pattern. In the figure, the inner tread half Si is provided with an inner slanted horizontal main groove 11 consisting of only the first inner slanted horizontal main groove 11A, and the outer tread half So is provided with a An outer slanted horizontal main groove 20 composed of only the outer slanted horizontal main groove 20A is provided.
[0039]
Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment, and may be implemented in various forms without being limited to the illustrated embodiment, such as a general passenger car tire. .
[0040]
【Example】
A pneumatic tire (255 / 40ZR17) having the structure shown in FIG. 1 and having the tread pattern shown in FIGS. 2, 6, and 7 was prototyped according to the specifications shown in Table 1, and the wet grip performance of each test tire and gymkhana competition. The running time was measured, and the results are shown in Table 1. The specifications other than Table 1 are substantially the same.
[0041]
(1) Wet grip performance (linear hydroplaning resistance):
The test tires were accelerated on a straight road at a depth of 10 mm using a passenger vehicle (2600 cc) mounted on all wheels under the conditions of a rim (9 J × 17) and internal pressure (230 kPa), and the acceleration limit speed was measured. It was indicated by an index with Example 1 being 100. The higher the value, the better.
[0042]
(2) Wet grip performance (lateral hydroplaning resistance):
Using the above vehicle, the vehicle is entered on a 100 m radius asphalt road surface on a course provided with a puddle having a depth of 5 mm and a length of 20 m while increasing the speed stepwise, and the lateral acceleration (lateral G) is measured. The average lateral G of the front wheels at a speed of 80 km / h was calculated. Then, the average lateral G was represented by an index with Comparative Example 1 being 100. The higher the value, the better.
[0043]
[Table 1]

[0044]
It can be confirmed that the tires of the examples can enhance both wet grip performance and dry grip performance.
[0045]
【The invention's effect】
Since the present invention is configured as described above, it is possible to appropriately increase the pattern rigidity while ensuring excellent drainage, and to improve dry grip performance, hydroplaning resistance, and abrasion resistance.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of a pneumatic tire according to the present invention.
FIG. 2 is a developed view showing the tread pattern.
FIG. 3 is a cross-sectional view of a circumferential main groove.
FIGS. 4A and 4B are diagrams illustrating the inclination angle of a groove wall surface of a circumferential main groove.
FIG. 5 is a diagram showing an example of a circumferential groove removed from an outer tread half.
FIG. 6 is a development view showing another embodiment of the tread pattern used in the present invention.
FIGS. 7A and 7B are development views showing an example of a tread pattern of a conventional tire.
[Explanation of symbols]
2S Tread surface 10 Circumferential main groove 20 Slope horizontal main groove 20A Outside first slant horizontal main groove 20B Second slant horizontal main groove 21 Communication part 22o inside horizontal groove main part 22i Communication part C outside Tire equators E, Ei, Eo Tread edge g Tread half within groove wall Si, Tread half outside So

Claims (5)

On the tread surface, a pneumatic tire provided with an asymmetric pattern in which the tread pattern is different on both sides of the tire equator,
The tread surface is centered on the tire equator, and in a state in which the tire is mounted on the vehicle, the tread half portion inside the vehicle and the outer tread half portion outside the vehicle are virtually divided, and the inner tread half portion. The groove area ratio Li of the tread pattern is 0.05 or more larger than the groove area ratio Lo of the tread pattern in the outer half of the tread outside the vehicle, and the groove area ratio L of the tread pattern on the entire tread surface is 0.15. ~ 0.35,
The tread half portion includes a linear circumferential main groove extending continuously in the tire circumferential direction in a region Y separated from the tire equator by a distance of 20 to 55% of a tread half width from the tire equator to the tread edge. And the inclination angle α with respect to the normal to the tread surface of the groove wall surface of the circumferential main groove is set to 30 to 50 °,
In the outer tread half, without providing a circumferential groove extending continuously in the tire circumferential direction,
Moreover, the outer half of the tread has an outer inclined main groove having an inner end extending toward the tread end with the inner end being a tire equator and having an inclined angle β of 35 ° or more with respect to the tire circumferential direction. Yes,
And the outer inclined horizontal main groove communicates with the inner end of the horizontal groove main portion and communicates with the circumferential main groove beyond the tire equator, or the outer end of the horizontal groove main portion and the tread end. A pneumatic tire having an outer communicating portion communicating with the tire, and the inclination angle β at a communicating position of each communicating portion is set to 75 to 90 °. 2. The pneumatic tire according to claim 1, wherein the outer inclined lateral main groove is formed only of a first outer inclined lateral main groove having an outer communicating portion connected to the lateral groove main portion. 3. The outer inclined horizontal main groove has a first outer inclined horizontal main groove having an outer communicating portion connected to the lateral groove main portion, and a second outer inclined main groove having the inner communicating portion connected to the lateral groove main portion. The pneumatic tire according to claim 1, further comprising a lateral main groove. 4. The outer inclined horizontal main groove, wherein the first outer inclined horizontal main groove and the second outer inclined horizontal main groove are alternately arranged in the circumferential direction. 5. Pneumatic tires. The tread surface is a ratio Hi / Ho of a radial distance Hi of the tread end of the inner tread half from the tire equatorial point to a radial distance Ho of the outer tread half of the tread end from the tire equatorial point. Was set to 1.02 to 1.20, the pneumatic tire according to any one of claims 1 to 4.

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