JP3894777B2 - Pneumatic tire - Google Patents

Description

表１から明らかなように、本発明の構成からなるタイヤ（実施例１〜５）は制動停止距離が短く、高速走行時の湿潤路面におけるＡＢＳ制動性能に優れていることがわかる。
【００２９】
【発明の効果】
上述したように本発明の空気入りタイヤによれば、トレッド面の接地領域内におけるタイヤ幅方向のエッジの合計長さＬｅを１５００〜３０００ｍｍとし、トレッド面の単位面積（１ｃｍ² ）あたりの周方向剛性Ｃｘを５〜８Ｎ／ｍｍとしたため、ＡＢＳ制動機構による湿潤路面における制動停止距離に影響を与える、接地領域内のエッジ成分長さを規定し、周方向剛性を最適化したことにより、高速走行時に湿潤路で優れたＡＢＳ制動性能を発揮することができる。
【図面の簡単な説明】
【図１】本発明の空気入りタイヤに設けられるトレッドパターンの一例を示す平面図である。
【符号の説明】
１ 主溝
２ ラグ溝
３ リブ
４ ブロック
５ サイプ
６ エッジ
７ 接地領域[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that makes it possible to more effectively exhibit ABS (anti-lock brake system) braking performance on wet road surfaces.
[0002]
[Prior art]
If the brakes are applied suddenly while driving the vehicle on a wet road surface, the tires may lock and cause side slipping, etc., and the steering wheel operation may not work, leading to an accident.
[0003]
An anti-lock brake system (hereinafter referred to as “ABS”) has been developed as a measure for preventing the phenomenon that the steering wheel control is not effective when the brake is suddenly applied on a wet road surface.
[0004]
This ABS does not completely lock the tire at the time of sudden braking, but the friction coefficient between the tire and the road surface is maximized by sliding the tire against the road surface so that the slip rate is about 5 to 15%. This is a mechanism that keeps the handle in a controlled manner and stops while maintaining the controllability of the handle.
[0005]
However, this ABS makes it possible to stop while maintaining the controllability of the steering wheel, but it is a method of controlling while allowing a certain slip ratio as described above, so there is a problem that the braking stop distance becomes long. It was.
[0006]
Conventionally, in order to solve this problem, the circumferential length per unit area of the tread surface and the total length of the width direction components projected in the tire axial direction of the edge of the tread pattern per unit length in the circumferential direction are within a predetermined range. There was a proposal to use a specified pneumatic tire. However, in this proposal, it cannot be said that the braking stop distance by the ABS control mechanism is necessarily shortened, and the tendency is particularly prominent during braking from high speed running.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a pneumatic tire that can further reduce a braking distance by an ABS (anti-lock braking system) braking mechanism on a wet road surface.
[0008]
[Means for Solving the Problems]
The pneumatic tire of the present invention that achieves the above object is a pneumatic tire having a tread pattern formed by a main groove extending in the tire circumferential direction and a lug groove extending in the tire width direction or a lug groove and a sipe on the tread surface. The total length Le of the edges in the tire width direction in the contact area of the tread surface is 1500 to 3000 mm, and the circumferential rigidity Cx per unit area (1 cm ² ) of the contact area is 5 to 8 N / mm. It is characterized by.
[0009]
Thus, the total length Le of the edges in the tire width direction in the contact area of the tread surface is 1500 to 3000 mm, and the circumferential rigidity Cx per unit area (1 cm ² ) of the contact area is 5 to 8 N / mm. Therefore, by defining the edge component length in the ground contact area that affects the braking stop distance by the ABS braking mechanism on wet road surfaces and optimizing the circumferential rigidity, the braking distance by the ABS braking mechanism can be further shortened. be able to.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
[0011]
FIG. 1 is a plan view of a tread surface of a pneumatic tire according to the present invention.
[0012]
In FIG. 1, a rib 3 is formed at the center in the tire width direction by a main groove 1 extending in the tire circumferential direction on the tread surface, and a block 4 is partitioned by a main groove 1 and a lug groove 2 extending in the tire width direction on both outer sides thereof. Has been. Further, each block 4 is provided with a sipe 5 extending in the tire width direction.
[0013]
Reference numeral 7 denotes a contact area when the tire contacts the road surface, W denotes a contact width of the contact area 7, and a denotes a contact length. The ground contact area 7 is an area when the tire is assembled on a regular rim, filled with a regular internal pressure and loaded with a regular load to be grounded on a flat road surface.
[0014]
In the pneumatic tire of the present invention, the total length Le existing in the ground contact region 7 of the edge 6 in the tire width direction formed in the block 4 by the lug groove 2 and the sipe 5 in the tread pattern formed as described above. The total sum of the lengths of the edges 6 in the tire width direction within the contact area is set to be 1500 mm to 3000 mm. Here, the edge in the tire width direction refers to an edge having a tire width direction component among edges formed by blocks or sipes, that is, the remaining edges excluding edges extending in the tire circumferential direction from all edges. Say.
[0015]
Le is defined by the following equation (1).
Le = L × (a / Lt) (1)
However,
L: the total length of the entire tire circumference at the edge in the tire width direction existing within the ground contact width W;
a: The grounding length of the grounding area,
Lt: tire outer peripheral length,
Defined by
[0016]
In other words, the total length Le of the edges in the tire width direction in the contact area is equal to the total length of the edges in the tire width direction over the entire circumference of the tire in the contact width W (the sum of the edge lengths). It is a value obtained by multiplying the ratio of the ground contact length to.
[0017]
Furthermore, the pneumatic tire of the present invention is set so that the circumferential rigidity Cx (N / mm) per unit area (1 cm ² ) of the tread surface in the ground contact region 7 is 5 to 8 N / mm. .
[0018]
Here, Cx is defined by the following equation (2).
Cx = [ΣCi × [1-2n × 0.212 × {0.263 × (hs / h) +0.529} ⁶ ]] / S (2)
However,
Ci: circumferential rigidity of blocks and ribs in the ground contact area,
S: Grounding area of the grounding area,
h: Height from groove bottom to surface of block or rib,
hs: depth of sipe,
n: number of sipes,
The circumferential rigidity Ci is calculated by the following equation (3).
Ci = 1 / (h ³ / 3EI + h / AG) (3)
However,
E: Young's modulus of tread rubber,
G: Shear elastic modulus of the tread rubber (G = E / 3),
I: sectional moment of the block or rib,
A: sectional area of block or rib,
Defined by Here, when calculating the circumferential rigidity Ci of the rib, “h” is set to “(1/2) h”.
[0019]
That is, the circumferential rigidity Cx per unit area is a value obtained by dividing the sum of the circumferential rigidity of each block or rib in the ground contact area by the ground contact area S.
[0020]
As described above, by defining the total length Le of the edges in the tire width direction within the ground contact region 7 and the circumferential rigidity Cx per unit area (1 cm ² ) of the tread surface, As is apparent, the coefficient of friction on the wet road surface when braking with a vehicle equipped with an ABS braking device can be increased, and the braking distance by the ABS braking mechanism can be further shortened.
[0021]
If the total length Le of the edges in the tire width direction in the ground contact area is smaller than 1500 mm, the edge component necessary for braking is insufficient and the edge effect is insufficient, so the braking stop distance becomes longer, and if it exceeds 3000 mm, the edge length However, it is not preferable because the block rigidity is lowered, and the deformation of the block becomes large and a sufficient edge effect cannot be exhibited.
[0022]
Also, during braking, if the tire receives a braking force and a shearing force is applied to the block, the contact pressure with the ground at the edge of the block on the tire traveling direction side increases locally, and the direction opposite to the tire traveling direction of the block The contact pressure of the side edge with the ground decreases. And in fact, since the edge portion with high contact pressure with the ground contributes to the braking effect, the braking distance becomes shorter when the length of the edge portion with high contact pressure is longer than the data of the examples described later. Become.
[0023]
When the circumferential rigidity Cx per unit area is less than 5 N / mm, the deformation of the block becomes large, and a sufficient edge effect on a wet road surface cannot be exhibited, and the braking distance by the ABS braking mechanism becomes long. It is not preferable. On the other hand, when the circumferential rigidity Cx is larger than 8 N / mm, the lug groove and the sipe length tend to be short, and the block deformation at the time of braking is small, so that a sufficient edge effect cannot be obtained, which is not preferable. Furthermore, noise performance and riding comfort performance are adversely affected, which is not preferable.
[0024]
In the above embodiment, a block pattern pneumatic tire having ribs provided at the center of the tread has been described as an example. However, the present invention is also applied to a block pattern pneumatic tire without ribs. The present invention is also applied to a case where no sipes are provided. In this case, n = 0 may be set in the equation (3).
[0025]
【Example】
Examples 1-5, Comparative Examples 1-6, Conventional tire sizes are common to 205 / 65R15 94H, and the circumferential rigidity Cx per unit area in the contact area and the total length of edges in the tire width direction in the contact area Pneumatic tires (Examples 1 to 5, Comparative Examples 1 to 6, and conventional examples) with Le as shown in Table 1 were manufactured.
[0026]
These 12 types of tires are assembled on a JATMA standard rim, mounted on a passenger car with an ABS mechanism with an air displacement of 200 kPa and a displacement of 3000 cc. Was measured.
[0027]
Brake stop distance measurement method The stop distance from the initial speed of 100 km / h to the stop is measured five times, and the average value of three times excluding the maximum and minimum values is set as the stop distance. The reciprocal number is shown as an index value of 100. The larger the index value, the better the braking performance.
The results are shown in Table 1.
[0028]
[Table 1]

As is apparent from Table 1, the tires (Examples 1 to 5) having the configuration of the present invention have a short braking stop distance and are excellent in ABS braking performance on a wet road surface during high-speed traveling.
[0029]
【The invention's effect】
As described above, according to the pneumatic tire of the present invention, the total length Le of the edges in the tire width direction in the contact area of the tread surface is 1500 to 3000 mm, and the circumferential direction per unit area (1 cm ² ) of the tread surface. Since the stiffness Cx is 5-8 N / mm, the edge component length in the ground contact area that affects the braking stop distance on the wet road surface by the ABS braking mechanism is specified, and the circumferential stiffness is optimized, resulting in high-speed running Sometimes it can exhibit excellent ABS braking performance on wet roads.
[Brief description of the drawings]
FIG. 1 is a plan view showing an example of a tread pattern provided in a pneumatic tire of the present invention.
[Explanation of symbols]
1 Main groove 2 Lug groove 3 Rib 4 Block 5 Sipe 6 Edge 7 Grounding area

Claims (3)

In a pneumatic tire having a tread pattern formed by a main groove extending in the tire circumferential direction and a lug groove extending in the tire width direction or a lug groove and a sipe on the tread surface, an edge in the tire width direction in a contact area of the tread surface A pneumatic tire having a total length Le of 1500 to 3000 mm and a circumferential rigidity Cx per unit area (1 cm ² ) of the ground contact region of 5 to 8 N / mm. The pneumatic tire according to claim 1, wherein the tread pattern is a pattern mainly composed of blocks. The pneumatic tire according to claim 2, comprising a rib at the center of the tread surface.

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