JP4428823B2 - Heavy duty pneumatic tire - Google Patents

Description

表１によれば、実施例タイヤでは、従来タイヤに比し、牽引力および泥はけ性の両者をともに大きく向上させ得ることが明らかである。
【００２４】
【発明の効果】
かくして、この発明によれば、悪路走行に際する泥はけ性を大きく向上させてトラクション性能の低下を防止するとともに、トラクション性能それ自体を直接的に向上させることができる。
【図面の簡単な説明】
【図１】 この発明の実施の形態を示すトレッドパターンの展開図である。
【図２】 従来タイヤを示すトレッドパターンの展開図である。
【符号の説明】
１ ラグ溝
２ 周方向溝
４ ラグ
５ 横断溝
６ センターブロック
７ 溝部
ＷＳ ラグのトレッド幅方向全体長さ
ＷＣ センターブロックの幅方向全体長さ
ＴＷ トレッド幅
Ｃ 中心線[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heavy-duty pneumatic tire having a lug with improved mud repellency and traction performance during rough road driving.
[0002]
[Prior art]
2. Description of the Related Art Conventional heavy-duty pneumatic tires having lugs, for example, pneumatic radial tires, have a tread pattern as illustrated in a developed view in FIG.
[0003]
The lug groove 21 is linearly inclined with an interval in the tread circumferential direction and opens at the tread end, and the circumferential groove that extends in a zigzag shape in the circumferential direction and communicates with the tip of the lug groove 21. 22, the lugs 23 are formed so that the opposite sides extend substantially in parallel and bend in a substantially “H” shape, and the circumferential grooves 22 and the inclined transverse grooves 24 connecting the lugs 23 extend the lugs 21. A center block 25 which is long in the present direction is defined, and a groove portion 26 extending substantially in parallel with the inclined transverse groove 24 is provided in the center portion of the center block 25.
[0004]
According to such a tread pattern, there is an advantage that heat storage due to heat generation of the lug during high-speed traveling can be effectively prevented by the heat radiation action of the groove portion, compared with the case where only the lug is provided in the tread portion.
[0005]
[Problems to be solved by the invention]
However, in such prior art, it is not clear how to set the relative or absolute shape and dimensions of the lug 23 in order to achieve excellent mud repellency and traction. Moreover, in the prior art, as shown in FIG. 2, the area occupied by the lug 23 is not so different from that of the groove 21, and the degree of deformation of the lug groove 21 during load rolling is not so great. Therefore, since the degree of opening of the lug groove 21 is small, mud is easily clogged in the mud road, and the clogged mud is not easily dropped. Since the center block 25 is emphasized by setting the length short, the traction performance when traveling on a rough road could not be sufficiently improved. As for the traction performance, recent experiments have confirmed that the ribs on both shoulder sides have a higher contribution ratio than the center block.
[0006]
The object of the present invention is to solve such problems of the prior art, and the purpose of the invention is to improve the mud repellency from the lug grooves and to reduce the traction performance. The object of the present invention is to provide a heavy-duty pneumatic tire that prevents and further improves the traction performance.
[0007]
[Means for Solving the Problems]
Heavy duty pneumatic tire of the present invention, for example, bent substantially "to" shape, with an opening to the tread end, and the lug grooves gradually decreasing width toward the tread center side, in the tread circumferential direction di Guzagu shape and has a Lula grayed partitioned by the extending circumferential groove, a zigzag pair of circumferential grooves, between the pair of circumferential grooves, the folding projection of the pair of circumferential grooves It has a center block that is partitioned by transverse grooves that communicate with each other, and the width of the lug that bends in the circumferential direction at the intermediate portion is changed from the tread end to the bent portion of the intermediate portion of the lug. with gradually increasing toward, the lag, the overall length of the tread width direction (WS), with the same overall length of the center block (WC) or 1/4 or less of the tread width (TW) It is obtained by the.
[0008]
According to this tire, by increasing the rigidity of the lug, it is possible to concentrate the external force input to the lug groove to increase the degree of deformation and to easily drop mud from the lug groove.
[0009]
Also, here, by specifying the overall length of the lug in the tread width direction as described above and making it sufficiently longer than that of the conventional technology, the traction performance at the time of tire load rolling in a muddy place It is possible to effectively expand the mud hold area on the side of the tread where the contribution ratio is high, thereby ensuring improvement in traction performance.
[0010]
By the way, the reason why the overall length (WS) of the lug in the tread width direction is equal to or greater than the overall length (WC) of the center block is to improve the traction performance, and in addition, the overall length of the lug ( The reason why WS) is set to 1/4 or more of the tread width (TW) is that if it is less than 1/4, it is not effective in improving the traction performance.
[0011]
Here, preferably, the groove width of the lug groove is gradually reduced toward the tread center side.
According to this, since the circumferential rigidity of the tread portion becomes uneven and the circumferential rigidity of the lug tends to increase, the protrusion of the tire at the time of load rolling is borne by the groove portion. As a result, the groove is easily opened, so that the mud repellency is improved.
[0012]
That is, when the vehicle travels in a muddy area, mud removal depends on the expansion deformation in the tread circumferential direction of the lug groove at the time of rolling out during the load rolling of the tire. Since the lug is symmetric with respect to the center line C, the circumferential rigidity of the pattern becomes uniform, and the force tends to be uniformly applied to the lug and lug groove. The lug part will also take charge, and the opening of the groove will worsen, so the mud repellency will be low.
[0013]
Moreover, according to this asymmetric structure, the rigidity of the lug inevitably increases, and the force with which the lug catches the road surface increases, so that the traction performance is also improved.
[0014]
In such a tire, when a groove is provided in the center portion of the center block, the traction performance can be further enhanced by trapping mud with the groove.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below based on the drawings.
FIG. 1 is a developed view of a tread pattern showing an embodiment of the present invention.
Note that the internal structure of the tire is the same as that of a general heavy-duty radial tire, and therefore illustration thereof is omitted.
[0016]
Here, the lug groove 1 is opened at each tread end, is bent in a substantially “h” shape at the middle portion, and gradually decreases in width toward the tread center side, and extends in a zigzag shape in the tread circumferential direction. A circumferential groove 2 communicating with the lug groove 1 defines a lug 4 having a substantially “h” shape, and the lug 4 has an asymmetric shape with respect to its center line C. The width in the circumferential direction of the tread is gradually increased toward the bent portion at the intermediate portion thereof.
[0017]
Further, the center block 6 is defined by a pair of the circumferential grooves 2 and 2 extending in a zigzag manner, and a transverse groove 5 that connects the bent protrusions between the circumferential grooves. As shown in the figure, a right-groove groove 7 extending in the diagonal direction of the center block 6 having a substantially parallelogram shape, for example, is provided.
[0018]
When each of the lug 4 and the center block 6 is partitioned as described above, the overall length WS of the lug 4 in the tread width direction is set to be equal to or larger than the same overall length WC of the center block 6 and the tread width TW is combined. 1/4 or more.
Preferably, the maximum width DS of the lugs 4 in the tread circumferential direction is 0.5 to 0.85 times the arrangement pitch P of the lugs 4.
[0019]
According to the tire configured as described above, the rigidity of the lug 4 is increased, the deformation degree of the lug groove 1 is effectively increased, and the mud removal performance when traveling on a rough road can be advantageously improved. Further, by increasing the overall length WS of the lug 4 and increasing the action area of the lug 4 against mud etc., the traction performance can be greatly enhanced.
[0020]
Moreover, when the groove width of the lug groove 1 is gradually reduced toward the tread center side, and the maximum width DS of the lug 4 is 0.5 to 0.85 times the lug arrangement pitch P, it is thicker than the conventional one. In this case, the rigidity of the lug 4 can be further increased, and further improvement in mud repellency and traction performance can be realized.
[0021]
【Example】
A tire for trucks and buses having a size of 315 / 80R22.5, which has the tread pattern shown in FIG. 1 and the tread pattern shown in FIG. 2, and the other structure is the same as that of the example tire. Each of the conventional tires was subjected to a traction test and a mud repellency test in a muddy area under load conditions, applied rim and air pressure in accordance with ETRT STANDARDDS MANUAL.
The results are shown in Table 1.
[0022]
Here, the traction force is indicated by an index value with the conventional tire as a control, and the larger the value, the better the result.The mud removability is measured by measuring the volume of mud remaining in the lug groove. The index value was used as a control, and the smaller the value, the better the result.
[0023]
[Table 1]

According to Table 1, it is clear that both the traction force and the mud repellency can be greatly improved in the example tire as compared with the conventional tire.
[0024]
【The invention's effect】
Thus, according to the present invention, it is possible to greatly improve the mud repellency when traveling on rough roads to prevent a decrease in traction performance and to directly improve the traction performance itself.
[Brief description of the drawings]
FIG. 1 is a development view of a tread pattern showing an embodiment of the present invention.
FIG. 2 is a development view of a tread pattern showing a conventional tire.
[Explanation of symbols]
1 Lug groove 2 Circumferential groove 4 Lug 5 Crossing groove 6 Center block 7 Groove portion WS Overall length WC in the tread width direction WC Overall length TW in the width direction of the center block TW Tread width C Center line

Claims (4)

The lug has a lug defined by a lug groove that opens at a tread end and a pair of circumferential grooves extending in a zigzag shape in the tread circumferential direction, and the pair of zigzag circumferential grooves and the pair of circumferential directions. A tire having a center block defined by a transverse groove that communicates the bent protrusions of the pair of circumferential grooves with each other between the grooves ,
While gradually increasing the tread circumferential width of the lug that bends in the circumferential direction at the intermediate part from the tread end toward the bent part of the intermediate part of the lug,
The lag, the entire tread width direction lengths (WS), with the same overall length of the center block (WC) above, the heavy duty pneumatic tire comprising as a quarter or more of the tread width (TW).   The heavy duty pneumatic tire according to claim 1, wherein the width of the lug groove is gradually reduced toward the tread center.   The heavy-duty pneumatic tire according to claim 1 or 2, wherein a maximum width (DS) of the lug in the tread circumferential direction is 0.5 to 0.85 times a lug arrangement pitch (P).   The heavy duty pneumatic tire according to any one of claims 1 to 3, wherein a groove is provided in a central portion of the center block.

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