JP3579090B2 - Heavy duty pneumatic tires - Google Patents

Description

【００３０】
【表２】

【００３１】
表２の結果から、本発明の実施例の重荷重用空気入りタイヤスタイヤは、比較例の重荷重用空気入りタイヤスタイヤに比べ、含水率の高い不整地での泥落とし性能性及びトラクション性能が向上していることが明らかとなった。
【００３２】
【発明の効果】
本発明の重荷重用空気入りタイヤは上記構成としたので、含水率の低い不整地での耐摩耗性、乗り心地性及びトラクション性等の基本性能を維持しつつ、含水率の高い不整地での泥落とし性能及びトラクション性を向上することができるという優れた効果を有する。
【図面の簡単な説明】
【図１】本発明の一実施例の重荷重用空気入りタイヤのトレッドの一部を示す平面図である。
【図２】図１の２−２線断面図である。
【図３】従来例の重荷重用空気入りタイヤのトレッドの一部を示す平面図である。
【符号の説明】
１０ 重荷重用空気入りタイヤ
１２ トレッド
１４ ラグ溝
１６ タイヤ赤道面
２６ プラットホーム[0001]
[Industrial applications]
The present invention relates to a heavy-duty pneumatic tire, and more particularly to a heavy-duty pneumatic tire having a pattern for improving running performance on soft roads.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a heavy-duty pneumatic tire disclosed in Japanese Patent Application Laid-Open No. 1-254405 is known as an example of a heavy-duty pneumatic tire mounted on a construction vehicle that travels on both rough terrain and leveling.
[0003]
As shown in FIG. 3, in the heavy duty pneumatic tire 70, one pitch P between the circumferential centers of the adjacent grooves 74 at the center of the tread 72 is divided into four equal parts. Among the negative ratios of the four areas, the negative comparison value that is the ratio between the maximum negative ratio and the minimum negative ratio is set to 1.22 or less.
[0004]
As a result, the heavy-duty pneumatic tire 70 has sufficient traction, skidability, and sufficient tire life, reduces occurrence of chipping failure of the block land portion 76, and improves ride comfort until the end of traveling. It can be maintained well.
[0005]
[Problems to be solved by the invention]
However, in the heavy duty pneumatic tire 70, there is a narrow portion 78 in the groove 74 in which the groove depth, the groove width orthogonal to the groove, the inclination angle of the groove wall, the radius of the arc at the groove bottom, and the like change. The constricted portion 78 functions as a weir, and mud (arrow F in FIG. 3) flowing in the groove 74 is blocked in the groove 74. Further, when mud is clogged in the narrowed portion 78, the mud is clogged with the nucleus as a nucleus, and the entire groove 74 is filled with mud. Note that mud is likely to be clogged in the lateral groove of the tread central portion 72B, which has a long distance to the tread end 72A serving as a mud discharge port.
[0006]
Therefore, the construction vehicle equipped with the heavy-duty pneumatic tire 70 has a high water content (defined as the ratio of the amount of change in gravity after leaving 100 g of mud left at room temperature and humidity for 24 hours to the original weight of 100 g), for example, When the vehicle travels on a muddy ground having a water content of 30% or more, mud is likely to be clogged in the groove 74. For this reason, there was a problem that the shear resistance against the ground contact surface due to the lug pattern was significantly reduced, and the traction on muddy ground was greatly reduced.
[0007]
In consideration of the above facts, the present invention maintains the basic performance such as abrasion resistance on rough terrain having a low water content, ride comfort and traction, and also has the performance of removing mud and traction on rough terrain having a high water content. It is an object of the present invention to obtain a heavy-duty pneumatic tire capable of improving the load.
[0008]
[Means for Solving the Problems]
The heavy-duty pneumatic tire according to the present invention according to claim 1, includes a plurality of lug grooves crossing the tread substantially in the tire width direction, lugs defined by the lug grooves, and right and left sides of a tire equatorial plane of the lugs. And a platform shallower than the lug groove for connecting the lug grooves adjacent to each other and dividing the lug into approximately three equal parts, wherein the lug groove has a central area in a range of approximately half the tread width. The lug grooves have substantially the same cross-sectional shape, and the cross-sectional area of the lug groove gradually increases from the center toward the tread end in both side regions.
[0009]
According to a second aspect of the present invention, in the heavy duty pneumatic tire according to the first aspect of the present invention, a ratio of a width of the lug groove to a depth is 1.3 or more and 2.5 or less. And
[0010]
According to a third aspect of the present invention, in the heavy duty pneumatic tire according to the first aspect of the present invention, a cross-sectional inclination angle of a groove wall of the lug groove is 25 ° or more and 35 ° or less. .
[0011]
[Action]
In general, in order for the mud clogged in the lug grooves to fall, a condition is that the force of the mud falling by its own weight is greater than the adhesive force between the mud and the groove wall. Further, the lug vibrates during the rolling of the tire and the mud is peeled off from the lug groove wall, which is one factor for the mud to fall. In the vibration of the lug, the shape of the lug groove, that is, the groove width, the groove depth, and the sectional inclination angle of the groove wall are important parameters.
[0012]
Therefore, in the heavy-duty pneumatic tire according to the present invention, the lug is formed by connecting lug grooves adjacent to each other on both the left and right sides of the tire equatorial plane of the lug and dividing the lug into approximately three equal parts. A pair of shallower platforms are provided, and by these platforms, the sideslip of the tire can be prevented, and the respective parts of the lugs adjacent via the platforms vibrate integrally during the rolling of the tire. Due to the expansion of the groove, mud in the lug groove can be easily dropped.
[0013]
In addition, since the cross-sectional shape of the lug groove is substantially the same in the central region in the range of approximately one half of the tread width, and the cross-sectional area of the lug groove gradually increases from the center to the tread edge in both side regions. The mud in the lug groove moving from the center to the tread edge along the lug groove can be easily dropped.
[0014]
Accordingly, the performance of removing mud on uneven terrain having a high moisture content is improved, and the traction is also improved.
[0015]
If the ratio of the width to the depth of the lag groove is less than 1.3, the width relative to the depth of the lag groove is small, so that the mud stuck in the lag groove is unlikely to fall. On the other hand, when the ratio of the width to the depth of the lug groove exceeds 2.5, the width of the lug groove increases relative to the depth of the lug groove, so that the lug width becomes narrow and the wear resistance deteriorates, or the lug groove depth decreases. And the desired tire life cannot be set. For this reason, the ratio of the width to the depth of the lug groove is set to 1.3 or more and 2.5 or less.
[0016]
When the cross-sectional inclination angle of the groove wall of the lug groove is less than 25 °, the opening angle of the opposing groove wall of the lug groove is small, so that the mud stuck in the lug groove does not easily fall. On the other hand, when the cross-sectional inclination angle of the groove wall of the lug groove exceeds 35 °, in order to secure the standard lug groove depth, the lug width becomes narrow, and the land area must be reduced, resulting in abrasion resistance. The tire performance deteriorates, and the desired tire life cannot be set. For this reason, the cross-sectional inclination angle of the groove wall of the lug groove is set to 25 ° or more and 35 ° or less.
[0017]
【Example】
One embodiment of the heavy duty pneumatic tire of the present invention will be described with reference to FIGS.
[0018]
As shown in FIG. 1, the heavy-duty pneumatic tire 10 has a tire size of 30 / 65R25 (outer diameter 1625 mm, maximum width 765 mm, tread width 643 mm, crown R1600 mm). A plurality of lug grooves 14 are formed along the width direction (the left-right direction in FIG. 1). The groove swing angle β of the tangent line S of the line L passing through the center of the groove width of the lug grooves 14 with respect to the tire width direction (the left-right direction in FIG. 1) is set to 30 ° or less. Drop.
[0019]
These lug grooves 14 are bent in a wave shape and are formed at predetermined intervals in the tire circumferential direction, and the lugs 22 are partitioned by the lug grooves 14. On both left and right sides of the tire equatorial plane 24 of the lug 22, a pair of platforms 26 for dividing the lug 22 into approximately three equal parts in the tire width direction are formed. These platforms 26 are shallower than the lug grooves 14 and are adjacent to each other. Are connected to each other.
[0020]
The ratio (L / D) of the width L (L1 or L2) to the depth D of the lug groove 14 shown in FIG. 2 is 1.3 or more and 2.5 or less, and the cross-sectional inclination of the groove wall 14A of the lug groove 14 Angle α is not less than 25 ° and not more than 35 °. Further, a connecting portion 14C between the groove wall 14A and the groove bottom 14B has an arc shape.
[0021]
As shown in FIG. 1, the lug grooves 14 have substantially the same cross-sectional shape (shape in FIG. 2) in a central region X in a range of approximately half the tread width TW, and both side regions Y (shoulder portions). ), The cross-sectional area of the lug groove 14 gradually increases from the center side toward the tread end, and the lug groove outside the shoulder portion Y is larger than the groove width L1 of the lug groove 14 inside the shoulder portion Y. Fourteen groove widths L2 are wide. That is, the cross-sectional shape of the lug groove 14 at the tread end is a shape indicated by a broken line in FIG.
[0022]
Next, the operation of the present embodiment will be described.
In the heavy-duty pneumatic tire 10 of the present embodiment, a platform 26 is provided on a lug 22 defined by a lug groove 14 having a low groove swing angle (β ≦ 30 °). In addition to preventing sideslip, each part of the lug 22 adjacent via the platform 26 vibrates integrally during rolling of the tire, and the vibration spreads the lug groove 14 so that mud in the lug groove 14 easily falls. Can be done.
[0023]
Further, the cross-sectional shape of the lug groove 14 is substantially the same in the central region X in a range of approximately one half of the tread width, and the cross-sectional area of the lug groove 14 in the both side regions Y is from the center to the tread edge. Since it gradually increases, the mud in the lug groove 14 that moves from the center side along the lug groove 14 toward the tread end (the direction of arrow A in FIG. 1) can be easily dropped.
[0024]
Therefore, the performance of removing mud on uneven terrain having a high moisture content is improved, and the traction is also improved.
[0025]
When the ratio (L / D) of the width L to the groove depth D of the lug groove 14 is less than 1.3, the width of the lug groove 14 relative to the groove depth is narrow, so that the mud stuck in the lug groove 14 falls. Difficult to do. On the other hand, when the ratio (L / D) of the width L to the groove depth D of the lug groove 14 exceeds 2.5, the lug width becomes narrower as the width of the lug groove 14 to the groove depth of the lug groove 14 increases. As a result, the wear resistance becomes poor or the lug groove depth becomes shallow, so that a desired tire life cannot be set. Therefore, the ratio (L / D) of the width L to the groove depth D of the lug groove 14 is 1.3 or more and 2.5 or less, preferably 1.4 or more and 2.5 or less.
[0026]
When the cross-sectional inclination angle α of the groove wall 14A of the lug groove 14 is less than 25 °, the opening angle of the opposing groove wall 14A of the lug groove 14 is small, so that the mud stuck in the lug groove 14 does not easily fall. On the other hand, when the cross-sectional inclination angle α of the groove wall 14A of the lug groove 14 exceeds 35 °, in order to secure the standard lug groove depth, the lug width is reduced and the land area has to be reduced. In addition, the wear resistance deteriorates, and a desired tire life cannot be set. For this reason, the cross-sectional inclination angle α of the groove wall 14A of the lug groove 14 is 25 ° or more and 35 ° or less, preferably 27 ° or more and 35 ° or less.
[0027]
In addition, the lug groove 14 traverses substantially in the tire width direction. If the groove swing angle β of the tangent S of the line L passing through the center of the groove width of the lug groove 14 with respect to the tire width direction is larger than 30 °, the tire is not rolled. Since the opening of the lug groove 14 is hardly developed, the groove swing angle β is set to 30 ° or less, preferably 20 ° or less.
(Test example)
In order to confirm the mud removal performance and the traction performance of the heavy duty pneumatic tire of the present example, each heavy duty pneumatic tire having the specifications shown in Table 1 and Comparative Examples was prepared. Except for the specifications shown in Table 1 for each of these heavy duty pneumatic tires, they are the same as the heavy duty pneumatic tire 10 of the present embodiment.
[0028]
Next, each of the heavy-duty pneumatic tires was mounted on an actual vehicle, and the vehicle was driven on a Kanto loam layer having a water content of 30%. The mud-dropping performance was measured. The results are shown in Table 2 using an index when all the mud is clogged with 0. In addition, the traction performance was measured, and the results are shown in Table 2 as an index with 100 when no slippage of the tire occurred and 0 when running was impossible due to slippage of the tire.
[0029]
[Table 1]

[0030]
[Table 2]

[0031]
From the results in Table 2, the pneumatic tire tire for heavy load of the example of the present invention has better mud dropping performance and traction performance on rough terrain having a high water content than the pneumatic tire tire for heavy load of the comparative example. It is clear that it has improved.
[0032]
【The invention's effect】
Since the heavy-duty pneumatic tire of the present invention is configured as described above, it maintains the basic performances such as abrasion resistance, riding comfort and traction on uneven terrain having a low moisture content, while maintaining the basic performance such as traction. It has an excellent effect of improving mud dropping performance and traction.
[Brief description of the drawings]
FIG. 1 is a plan view showing a part of a tread of a heavy duty pneumatic tire according to one embodiment of the present invention.
FIG. 2 is a sectional view taken along line 2-2 of FIG.
FIG. 3 is a plan view showing a part of a tread of a conventional heavy-duty pneumatic tire.
[Explanation of symbols]
10 Pneumatic tire for heavy load 12 Tread 14 Lug groove 16 Tire Equatorial plane 26 Platform

Claims (3)

A plurality of lug grooves that cross the tread substantially in the tire width direction, a lug defined by the lug grooves, and a pair of lug grooves formed on the left and right sides of the tire equatorial plane of the lugs and connecting mutually adjacent lug grooves, and connecting the lugs. A platform shallower than the lug groove, which divides into approximately three equal parts, wherein the lug groove has substantially the same cross-sectional shape in a central region in a range of approximately half the tread width, A pneumatic tire for heavy loads, characterized in that the area of the cross section of the lug groove gradually increases from the center to the tread edge. The heavy duty pneumatic tire according to claim 1, wherein a ratio of a width to a depth of the lug groove is 1.3 or more and 2.5 or less. The pneumatic tire for heavy load according to claim 1, wherein a cross-sectional inclination angle of a groove wall of the lug groove is 25 ° or more and 35 ° or less.

Images