JP3616150B2 - Heavy duty studless pneumatic tire - Google Patents

Description

【００２１】
【表２】

【００２２】
テスト条件として、タイヤは夫々１６×５．５Ｆリムに組み、５．５Ｋｇｆ／ｃｍ^２ の内圧を充填した。
テスト方法は次の通りである
氷上（雪上）操縦安定性：
氷結フィ−ルド（雪上の場合は圧雪フィ−ルド）にコ−ナリング性、旋回性にポイントを置き設定した特設コ−スをパネラ−の運転技量に応じて走行（２０〜６０Ｋｍ／ｈ）し、フィ−リングにより評価した。
氷上（雪上）加速性：
氷結路上（雪上の場合は圧雪路上）で加速がスム−ズに行えるかどうか、またその時のふらつきの度合いをフィ−リングにより評価した。
氷上（雪上）制動性：
氷結路上（雪上の場合は圧雪路上）において直進初速３０Ｋｍ／ｈでタイヤにブレ−キをかけ、その地点から停止地点までの距離を測定した。
【００２３】
【表３】

【００２４】
ヒ−ルアンドトウ摩耗は、比較例のタイヤが中間ブロックを中心に著しく発生したのに対し、実施例のタイヤには殆ど認められなかった。
【００２５】
このように、中央陸部および中間陸部が多数のラグ溝によって区分されたブロックの列を形成する一方、ショルダ−陸部は、周方向に所定間隔を置きトレッド端から軸方向内側に向かってこの陸部の中途まで延びる多数の広幅ラグ溝によって、片歯の櫛状に実質上連なる周方向リブとし、このリブおよび上記ブロックに複数の横向きサイプを備えた本発明の重荷重用スタッドレス空気入りタイヤは、車両積荷時における優れた氷上性能と耐偏摩耗を発揮するのである。
【図面の簡単な説明】
【図１】本発明の実施例を示すトレッド平面図。
【図２】比較例のトレッド平面図
【符号の説明】
１ トレッド
２ 周方向主溝
３ 陸部
４ ラグ溝
５ ブロック
６ 横向きサイプ
８ 広幅ラグ溝
９ リブ[0001]
[Industrial application fields]
The present invention relates to a heavy-duty studless pneumatic tire having excellent running performance on icy and snowy road surfaces.
[0002]
[Prior art]
Since the use of spike tires to eliminate dust pollution caused by spikes or studs protruding on the surface of the tread has been banned, various developments have been made aiming at tires with excellent running performance on snowy and snowy road surfaces that do not have spikes. . These are collectively referred to as studless tires. A feature that is almost common to the studless tire is that the tread surface is divided into a large number of blocks and a large number of sipes are applied. Various forms of this sipe are possible, and various proposals have been made so far, and all of them aim to improve the slip resistance on ice by the edge effect of the block corner by the sipe.
[0003]
FIG. 2 is a plan view of a tread shown as an example of a studless tire. In FIG. 2, the tread 1 is provided with a main groove 2 extending in a deformed crank shape or a deformed zigzag shape on the equatorial plane O and on both sides thereof, and between the main groove 2 and the tread end E 2. The six land portions 3 are divided and further divided into independent blocks 5 by a large number of lug grooves 4 crossing them. In this case, a negative rate (ratio of the total area of the groove portion to the tread area) is set in preparation for running on snow. Giving big. On the other hand, for running on ice, the block 5 is siped horizontally and vertically so as to give an edge effect in a direction substantially perpendicular to the direction in which these forces act to external forces acting during driving, braking and cornering. Many 6 and 7 are provided.
[0004]
[Problems to be solved by the invention]
A tread with such a structure, not only when traveling on snow, but as a general tendency when traveling on ice, the negative force increases, that is, the frictional force decreases due to the decrease in the effective contact area that actually contacts the road surface. by only the edge effect, it is difficult to compensate for a decrease friction. Even so, even if we try to reduce the negative rate, there will be a restriction on the performance on snow, which is reduced accordingly.
[0005]
On the other hand, unlike passenger car tires, heavy-duty tires with high internal pressure applied, and light-duty truck tires whose load fluctuates significantly between hollow and loaded vehicles, the surface on the tread edge faces on the hard ice when loaded. The ground pressure is concentrated on the shoulder block, and low-elastic rubber is used in the tread to improve the performance on ice. Crushing occurs in the block, and as a result, it is difficult to function effectively. Further, there has been a problem that the occurrence of uneven wear due to the crushing, particularly the generation of wear and toe wear, is remarkable. The present invention has been made based on the above findings, and an object of the present invention is to provide a studless pneumatic tire excellent in icy and snowy road running performance and uneven wear resistance.
[0006]
[Means for Solving the Problems]
The present invention provides a central land portion, a pair of shoulder land portions adjacent to both ends of the tread surface, and an intermediate land between these land portions, which are partitioned by a cylindrical tread surface portion by at least four circumferential main grooves. in a tire having a tread and a section, a circumferential main groove adjacent to the central land portion in the above one row, without exceeding its center line, together extend in and out of the left and right small deformations crank shape, The circumferential main groove adjacent to the shoulder land is extended without exceeding the groove center line with a larger left and right swing width than the circumferential main groove adjacent to the central land. Forms a row of blocks that are partitioned by a number of lug grooves crossing them, while the shoulder land portion is arranged at a predetermined interval in the circumferential direction, and the midway portion of the land portion is axially inward from the tread tread surface end. Extend to By providing a large number of wide lug grooves wider than the lug grooves, a single-tooth comb shape is formed, and the shoulder land portion is narrow enough to close when a longitudinal force acts on the ground plane. By providing a groove or sipe, a circumferential rib substantially continuous in the circumferential direction is provided, and the rib and the block have a plurality of lateral sipes.
[0007]
The shoulder land portion is preferably an apparent block row divided by a narrow groove extending between the tip of the wide lug groove and the main groove adjacent to the land portion.
[0008]
[Action]
Heavy duty studless tire of the present invention, a circumferential main groove adjacent to the central land portion in the above one row, without exceeding its center line, together extend in and out of the left and right small deformations crank shape, the shoulder land The circumferential main groove adjacent to the central portion extends with a greater left and right swing width than the circumferential main groove adjacent to the central land portion without exceeding the groove center line, and is also partitioned by the circumferential main groove. The central and middle land portions form a row of blocks separated by a number of lug grooves crossing them, while the shoulder land portions are spaced in the circumferential direction from the tread tread edge to the axially inner side. A large number of wide lug grooves that extend to the middle of the land portion and wider than the lug groove are formed into a single-toothed comb shape. A structural feature is that by providing a narrow groove or sipe that closes when a directional force is applied, a circumferential rib substantially continuous in the circumferential direction is provided, and the rib and the block have a plurality of lateral sipe. And
The shoulder land portion thus forms a circumferential rib that is substantially continuous in a single-tooth comb shape, so unlike the block sectioned by the lug groove, the land portion rigidity that may be a concern even if a large amount of lateral sipe is used. Less likely to cause a decline. As a result, the effective contact area of the tread shoulder land, which is a heavy burden when traveling on ice in a loaded state, increases with lateral sipe, and as a result, the driving force and braking performance are particularly improved due to the increased frictional force and the edge effect of sipe. At the same time, wear and toe wear is advantageously reduced.
[0009]
On the other hand, in running on snow, the comb-shaped shoulder land portion functions substantially as a block under the action of the wide lug groove, and load holding can be achieved as usual.
[0010]
When the shoulder-land portion is apparently divided into blocks by providing a narrow groove that closes when a longitudinal force is applied within the ground plane, the function of the blocks independent of each other and the longitudinal force Has a function as a rib by the cooperation of these blocks, and an edge effect by the provided narrow groove can be obtained.
Further, when the shoulder land portion is an endless rib, the edge effect of the increased sipe landing portion is improved without causing an undesired decrease in rigidity even when a large amount of sideways sipe is used.
[0011]
【Example】
This will be described with reference to the drawings. FIG. 1 is a plan view of a tread showing an embodiment of the present invention.
Studless tire of the present invention is partitioned by the circumferential main grooves 2 of at least 4 on a cylindrical tread portion, a center land portion 3 _C, a pair of surfaces at both ends E of the tread portion shoulder - land portions 3 _S, and a tread 1 having a middle land portion _{3 M} between these land portions ₃ C, _{3 S.}
The central land portion 3 _C and the intermediate land portions 3 _M is a row of blocks 5 which are partitioned by a number of lug grooves 4 across them, whereas shoulder - land portions 3 _S has a tread placed a predetermined interval in the circumferential direction tread portion ends, or extending from the tread edge E to the middle of the land portions 3 _S toward axially inward, the wider than lug grooves 4, substantially continuous circumferential rib like a comb by providing a plurality of wide lug grooves 8 9 and the rib 9 and the block 5 have a plurality of lateral sipes 6.
[0012]
The shoulder-land portion 3 _S is provided with a narrow groove 10 that is narrow enough to close when a force in the front-rear direction passes between the tip of the wide lug groove 8 and the main groove 2 adjacent to the land portion 3 _S. Accordingly, it is preferable to divide into apparent blocks 5 ′, or to provide a sideways or similar sipe at the position of the narrow groove 10 instead.
[0013]
Although not shown, in the studless tire according to the present invention, the crown portion including the tread 1 straddling between the left and right side wheels and the both side wheels is connected to the toroidal, and the other side wall is passed through the crown portion from one side wall. -A carcass composed of at least one fiber cordial ply represented by nylon or polyester (usually two) or one steelcoil radial ply is placed between the cords. A reinforcing structure in which a non-extensible belt layer including a plurality of steel cord layers is disposed between the carcass and the tread 1 can be applied.
[0014]
FIG. 1 is an example of a tire for a small truck having a size of 6.50R16 10PR. The tread 1 has a pair of left and right main grooves 2 sandwiching the equator plane 0, and a pair of main grooves 2 extending in the circumferential direction on the outer side. A central land portion 3 _C , an intermediate land portion 3 _M having a wider ridge width on both sides thereof, and a shoulder-land portion 3 _S having a wider width on both sides thereof. Main groove adjacent to the central portion land portion 3 _C 2 is extended toward the circumferential direction out of the left and right small deformations crank shape without exceeding its center line j. Shoulder - the main groove 2 adjacent to the land portion 3 _S also, the left and right swing width is relatively large extend similar without exceeding the center line k of the groove be said. The width of the main groove 2 with respect to the tread width is 4.8% (7.0 mm / 146.4 mm). In addition, the range of 2-6% is suitable for both ratios.
The central land portion can be provided in a plurality of rows without being limited to one row between the intermediate land portions.
[0015]
Central portion 3 _C and the intermediate land portions 3 _M is substantially the number of lug grooves 4 transverse to the axial direction is bent in the middle provided, some vertically long land portion 3 _C position and land portions 3 _M is clogged relatively vertical Reclassified into block 5. On the other hand, the shoulder-land portion 3 _S has a wide lug groove (width 7.2 mm) 8 extending axially inward from the tread end to a position of 43% of the maximum width of the land portion 3 _S , thereby forming a one-tooth comb shape. Form a column. The width of the wide lug groove 8 with respect to the shoulder-land maximum width is 35 to 50%, the width of the lug groove 8 is wider than that of the lug groove 4 within the range of 5 to 10 mm, and the arrangement interval of the lug grooves 8 Are preferably provided in accordance with the distance between the lug grooves 4.
[0016]
The width of the narrow groove 10 that refracts in a crank shape from the tip of the wide lug groove 8 and extends across the land portion to the main groove 2 is 1.5 mm, and the depth is 70% of the depth of the wide lug groove 8. It is. The width and depth of the narrow groove 10 are preferably 0.7 to 2.0 mm and 60 to 75%, respectively, in light of the object of the present invention.
[0017]
In the block 5 ′ divided by the narrow grooves, four side sipe 6 extending zigzag from the tread end E and six from the main groove 2 are arranged to face each other at substantially equal intervals and are subdivided into portions 11. Further, a zigzag vertical sipe 7 that connects the ends of the wide lug groove 8 in the circumferential direction is provided in the space between the ends of the left and right horizontal sipe 6, and the block 5 'is apparently divided in the axial direction. Even if the block 5 ′ is subdivided in this way, consideration is given to the fact that the portion 11 can mutually influence and cope with the external force, particularly the lateral force, which acts due to the zigzag component. The same applies to the bent portion (longitudinal center position) of the narrow groove 10 that divides the point block 5 ′.
[0018]
Block 5 of the middle land portion 3 _M are equally spaced sideways sipe 6 terminating in a block extending from both axial ends in a zigzag, are provided and alternately present 4. Also block 5 of the central land portion 3 _C, the zig-zag transverse sipes 6 according to the block of the middle land portion 3 _M are provided six. The shoulder - land portions 3 _S, the central land portion 3 _C, and the sipes than the intermediate land portion 3 _M densely arranged.
[0019]
【effect】
In order to confirm the effect of the tire of the present invention constructed as described above, a radial structure of 650R16 10PR size is applied, and the provision of a small truck between the tire of the example shown in FIG. 1 and the tire of the comparative example shown in FIG. An evaluation was made by carrying out an actual vehicle test on ice and snow under load conditions and a wheel and toe wear test by running 13,000 km (speed 80 km / h ) on an asphalt pavement.
Table 1 shows the total length of the edge components with respect to the lateral force formed on the treads of both types of tires, and Table 2 shows the total length of the edge components with respect to the longitudinal force.
[0020]
[Table 1]

[0021]
[Table 2]

[0022]
As test conditions, the tires were assembled in 16 × 5.5F rims and filled with an internal pressure of 5.5 kgf / cm ² .
The test method is as follows: Steering stability on ice (on snow):
Run a special course (20-60km / h ) according to the driving skill of the panel, with the cornering and turning characteristics set on the frozen field (pressed snow field in case of snow). And evaluated by filling.
Acceleration on ice (on snow):
Whether or not acceleration could be smoothly performed on an icy road (on a snowy road in the case of snow) and the degree of wobbling at that time were evaluated by feeling.
On-ice (snow) braking performance:
The tire was braked at an initial speed of 30 Km / h on an icy road (on a snowy road in the case of snow), and the distance from that point to the stop point was measured.
[0023]
[Table 3]

[0024]
The wheel and toe wear occurred remarkably in the tire of the comparative example centering on the intermediate block, but was hardly observed in the tire of the example.
[0025]
Thus, while the central land portion and the middle land portion to form a row of blocks is divided by a number of lug grooves, shoulder - land portion is circumferentially placed a predetermined distance toward the tread end axially inwardly A large number of wide lug grooves extending to the middle of the land portion are used as circumferential ribs that are substantially continuous in a single-tooth comb shape, and the rib and the block are provided with a plurality of laterally oriented sipes. The tire exhibits excellent performance on ice and uneven wear resistance when the vehicle is loaded.
[Brief description of the drawings]
FIG. 1 is a plan view of a tread showing an embodiment of the present invention.
[Fig. 2] Tread plan view of comparative example [Explanation of symbols]
1 Tread 2 Circumferential Main Groove 3 Land 4 Lug Groove 5 Block 6 Sideways Sipe 8 Wide Lug Groove 9 Rib

Claims (2)

A cylindrical tread has a central land portion defined by at least four circumferential main grooves, a pair of shoulder land portions adjacent to both ends of the tread, and an intermediate land portion between these land portions. In tires with treads,
The circumferential main grooves adjacent to the central land portion in the above one row, without exceeding its center line, together extend in and out is less deformed crank shape in the left and right, a circumferential main groove adjacent to the shoulder land portion The width of the left and right is larger than the circumferential main groove adjacent to the central land, and it extends without crossing the groove center line, and the center and middle land of the tread are divided by a number of lug grooves across them. While forming a row of the blocks, the shoulder land portions are arranged at predetermined intervals in the circumferential direction and extend from the tread tread surface end toward the inside in the axial direction to the middle of the land portions. By providing a single-tooth comb shape by providing a wide-width lug groove, and by providing a narrow groove or sipe that closes this shoulder land portion when a longitudinal force is applied within the ground plane Circumferentially and substantially continuous circumferential rib, heavy duty studless pneumatic tire characterized by having a plurality of lateral sipes in the rib and the block. 2. The heavy duty studless pneumatic tire according to claim 1, wherein the shoulder land portion includes an apparent block row divided by narrow grooves extending between a front end of a wide lug groove and a main groove adjacent to the land portion. 3. .

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