JP2005014628A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an off-road pneumatic tire further improved in traveling performance on a muddy road without degrading noise performance and traveling performance on a sandy place. <P>SOLUTION: The pneumatic tire has a tread pattern in which two zigzag main grooves 2, 3 extending paralelly in the circumferential direction in a tire center region, and a plurality of tilted lug grooves 4 extending paralelly from bent parts 2a, 3a of the main grooves 2, 3 to both shoulder S, S sides respectively are arranged. The bending angle θ of the main grooves is set from 75° to 140°, the tilt angle β of the lug grooves to the tire circumferential direction is set from 45° to 60°, and the width W of the main grooves 2, 3 is set from 2 to 4% of a tread expansion width TW. Furthermore, a ground contact area ratio of a tread surface 1 is set from 60 to 70% in a state where the tire is assembled to a normal rim and filled with a regular internal pressure, and 75% of a regular load is applied thereto. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

表１より、実施例１〜４は、ラグ溝４の傾斜角βと接地面積比率を本発明の規定範囲にしたことにより、砂地走行性能（及び騒音性能）を従来例のレベルに実質的に維持した状態で、泥濘地走行性能が向上したことがわかる。
【００１７】
【発明の効果】
上述したように、本発明の空気入りタイヤは、ジグザグ状の主溝の屈曲部からショルダー部に連通するように設けたラグ溝のタイヤ周方向に対する傾きを４５〜６０°の範囲にし、かつトレッド面の接地面積比率を６０〜７０％の範囲にしたことにより、泥濘地でのトラクションを増大することができる。
【００１８】
しかも、主溝のジグザグの屈曲角を７５〜１４０°とした上で、主溝幅をトレッド展開幅の２〜４％にしたことにより、騒音性能及び砂地走行性能を実質的に低下させることがない。
【図面の簡単な説明】
【図１】本発明の空気入りタイヤのトレッド面の一部を展開して示す平面図である。
【符号の説明】
１ トレッド面
２、３ 主溝
４ ラグ溝
５ サブ溝
Ｌ タイヤセンターライン
Ｓ ショルダー[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a pneumatic tire, and more particularly, a pneumatic tire for off-road driving that further improves muddy road running performance without substantially reducing noise performance and sandy road running performance improved by the prior art. About.
[0002]
[Prior art]
As a pneumatic tire suitable for off-road driving in sandy areas such as the Middle East desert region, the present applicant has reduced off-vehicle noise and improved sandy driving performance while ensuring off-road driving performance and hydroplaning performance. The proposed tire was proposed as Patent Document 1. In the tire of this Patent Document 1, a main groove in which a linear groove inclined at an angle of 20 to 40 ° with respect to the tire circumferential direction is bent in a zigzag shape at a bending angle of 90 to 140 ° in the center region of the tread surface is a tire. Two of them were arranged in the circumferential direction, and the width of the main groove was 3 to 7% of the developed tread width, and the contact area ratio of the land was 72% or more.
[0003]
This tire achieved the initial purpose by providing the zigzag main grooves as described above, but the performance on the muddy ground was further reduced from the market without further degradation of the sandy performance. It has been requested to improve (especially traction performance).
[0004]
[Patent Document 1]
JP 2002-12007 A (page 1-4, FIGS. 1 and 2)
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a pneumatic tire for off-road driving that further improves the muddy road running performance without lowering the noise performance and sandy road running performance in order to satisfy the above requirements. It is in.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the pneumatic tire of the present invention has two zigzag main grooves extending parallel to the tire center region in the circumferential direction on the tread surface, and both shoulder sides from the bent portions of the main grooves. In a pneumatic tire having a tread pattern in which a plurality of inclined lug grooves extending in parallel with each other is disposed, a bending angle formed by the main groove is 75 to 140 °, and an inclination angle of the lug groove with respect to the tire circumferential direction is 45 to 45 °. The tread surface in a state in which the groove width of the main groove is set to 2 to 4% of the tread development width at 60 °, and the tire is assembled in a normal rim and the normal internal pressure is filled and a load of 75% of the normal load is applied. The ground contact area ratio is 60 to 70%.
[0007]
In this way, the inclination of the lug groove provided so as to communicate from the bent portion of the zigzag main groove to the shoulder portion with respect to the tire circumferential direction is in a range of 45 to 60 ° larger than that of the conventional tire, and the tread surface is grounded. By changing the area ratio to a range of 60 to 70%, the traction in the muddy area can be increased. In addition, the bending angle of the zigzag in the main groove is set to approximately the same level as 75 to 140 °, and the main groove width is defined as a small range of 2 to 4% of the tread development width, so that the noise performance and the sandy traveling performance are achieved. Can be maintained at the level of conventional tires without substantially lowering.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
[0009]
FIG. 1 is a plan view showing a part of a tread surface of a pneumatic tire according to the present invention. On the tread surface 1 of the pneumatic tire, two zigzag main grooves 2 and 3 extending in parallel to the circumferential direction across the tire center line L, and both shoulders S from the bent portions of the main grooves 2 and 3, respectively. A non-directional tread pattern is formed by arranging a plurality of slanted lug grooves 4, 4,. In this embodiment, the two zigzag main grooves 2 and the apexes 2a and 3a of the main grooves 3 are positioned on the tire center line L, but these positions are arbitrarily set.
[0010]
In the tread pattern described above, the zigzag main grooves 2 and 3 have their bending angles θ set in the range of 75 to 140 °, and each lug groove 4 has an inclination angle β of 45 to 60 ° with respect to the tire circumferential direction. Is set in the range. Further, the groove width W of the main grooves 2 and 3 is set to 2 to 4% of the tread development width TW, and the ratio of the land contact area to the contact area of the tread contact surface is set to 60 to 70%. . Here, the contact area ratio refers to that in a state in which a tire is incorporated in a normal rim, filled with a normal internal pressure, and a load of 75% of the normal load is applied. The normal rim, normal internal pressure, and normal load refer to the rim, internal pressure, and load defined in the 2002 edition of JATMA, respectively.
[0011]
In the pneumatic tire of the present invention, the inclination angle β of the lug grooves 4, 4,... Passing through the shoulders S, S from the bent portions 2a, 3a of the zigzag main grooves 2, 3 is 45 to 45 as described above. By increasing the contact area ratio of the tread to 60 to 70% while increasing it to 60 ° as compared with the conventional tire, traction during muddy road traveling can be improved as compared with the conventional tire. On the other hand, the two zigzag main grooves 2 and 3 in the center portion have the bending angle θ in the range of 75 to 140 ° and are substantially the same level as the conventional tire, while the main groove width W is 2 to 2 of the tread deployment width TW. Since it is defined as small as 4%, sandy traveling performance and noise performance can be maintained substantially equal to the performance of conventional tires.
[0012]
If the bending angle θ of the main grooves 2 and 3 is less than 75 °, the problem of uneven wear occurs. On the other hand, if the bending angle θ exceeds 140 °, the sand running performance and the muddy ground running performance are deteriorated. As for the inclination of the lug grooves 4, 4,..., When the inclination angle β is less than 45 °, the muddy road running performance at a higher level than the object of the present invention is deteriorated. Will occur. Further, when the groove width W of the main grooves 2 and 3 is less than 2% of the tread developed width TW, the hydroplaning performance, muddy road running performance and sandy road running performance are lowered, and when it exceeds 4%, the noise performance is lowered. . Furthermore, when the contact area ratio is less than 60%, the noise performance is lowered, and when it exceeds 70%, the muddy road running performance is lowered.
[0013]
In the pneumatic tire of the present invention, in order to further improve the muddy road running performance, the groove width of the lug groove 4 is gradually expanded from the tire center line L side toward the shoulder S side, and enters the lug groove 4. It is preferable to make it easier to discharge mud. Further, if the sub-groove 5 that connects the straight groove portions of the main grooves 2 and 3 is disposed between the two main grooves 2 and 3, the muddy road running performance is further improved. be able to.
[0014]
[Experimental example]
The tire size (275 / 65R17) and the tread pattern (FIG. 1) are used in common, the contact area ratio, the main groove bending angle θ, the lug groove inclination angle β with respect to the tire circumferential direction, and the main groove width with respect to the tire development width. Conventional tires (conventional examples), tires of the present invention (Examples 1 to 4), and comparative tires (Comparative Examples 1 to 8) with different ratios as shown in Table 1 were produced.
[0015]
The above 13 types of tires are mounted on a rim (17 × 8JJ), filled with air pressure (200 kPa) and mounted on a vehicle, and the muddy ground running performance, noise performance and sandy running performance are evaluated by the following methods. The results are shown in Table 1.
[Muddyland running performance evaluation method]
The time elapsed while traveling a predetermined distance from a stopped state in a muddy area was measured. The results were evaluated by an index with the conventional example being 100. The larger the value, the better.
[Noise performance evaluation method]
External noise was measured when the vehicle was traveling straight at 50 km / h on the test course. The results were evaluated by an index with the conventional example being 100. The larger the value, the better.
[Sandland running performance evaluation method]
The vehicle was run on sandy ground, and the feeling evaluation was performed by two panelists. In addition, about what was divided | segmented, it displayed by connecting with "-".
[0016]
[Table 1]

From Table 1, Examples 1-4 are substantially equivalent to the level of a conventional sandy driving | running | working performance (and noise performance) by having made inclination-angle (beta) of the lug groove 4 and the contact area ratio into the prescription | regulation range of this invention. It can be seen that the muddy road running performance has been improved in the maintained state.
[0017]
【The invention's effect】
As described above, in the pneumatic tire of the present invention, the inclination of the lug groove provided so as to communicate from the bent portion of the zigzag main groove to the shoulder portion is in the range of 45 to 60 ° with respect to the tire circumferential direction, and the tread By setting the contact area ratio of the surface in the range of 60 to 70%, the traction in the muddy area can be increased.
[0018]
Moreover, the noise performance and sandy running performance can be substantially reduced by setting the main groove width to 2 to 4% of the tread development width after the zigzag bending angle of the main groove is set to 75 to 140 °. Absent.
[Brief description of the drawings]
FIG. 1 is a plan view showing a developed part of a tread surface of a pneumatic tire according to the present invention.
[Explanation of symbols]
1 Tread surface 2, 3 Main groove 4 Lug groove 5 Sub groove L Tire center line S Shoulder

Claims (2)

On the tread surface, two zigzag main grooves extending in the circumferential direction in the tire center region and a plurality of inclined lug grooves extending in parallel to both shoulder sides from the bent portions of the main grooves are arranged. In a pneumatic tire having a tread pattern,
The bending angle formed by the main groove is 75 to 140 °, the inclination angle of the lug groove with respect to the tire circumferential direction is 45 to 60 °, the groove width of the main groove is 2 to 4% of the tread development width, and the tire A pneumatic tire in which a contact area ratio of the tread surface is 60 to 70% in a state in which a normal internal pressure is filled and a load of 75% of a normal load is applied. The pneumatic tire according to claim 1, wherein a sub-groove that connects straight groove portions of the main groove is disposed between the two main grooves.

Images