JP4054097B2 - Heavy duty pneumatic radial tire - Google Patents

Description

【００１９】
表１によれば、実施例タイヤでは、ウェット性能および雪上性能ともに、従来タイヤに比して大きく向上することが明らかである。
また、比較タイヤでは、周方向細溝の存在の故に、ウェット性能を従来タイヤより幾分高めることができるが、とくに比較タイヤ１では、周方向細溝が直線溝であることから、雪上性能の向上を実現し得ないことが解かる。
【００２０】
【発明の効果】
以上に述べたところから明らかなように、この発明によれば、高い雪上性能を確保してなお、ウェット性能を大きく向上させることができる。
【図面の簡単な説明】
【図１】直線溝およびジグザグ溝の、溝幅とウェット制動性能および雪上制動性能との関係を示すグラフである。
【図２】この発明の実施形態を示す、トレッドパターンの展開図である。
【符号の説明】
１，２ 周方向主溝
３ 周方向細溝
４，５，６ 幅方向溝
７，８，９ ブロック
11, 12, 13 サイプ
14 段差リブ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heavy-duty pneumatic radial tire suitable for application to heavy-duty vehicles such as trucks and buses, and in particular, a studless tire, and in particular, achieves excellent wet performance.
[0002]
[Prior art]
As studless tires applied to trucks, buses, etc., a relatively wide circumferential main groove extending continuously in the tread circumferential direction has a zigzag extending form, and the circumferential main groove of the tread width direction Some edge components contribute to improving the traction performance on snow.
[0003]
[Problems to be solved by the invention]
However, in such a prior art, since the circumferential main groove extends in a zigzag shape, the virtual side segment of each groove side wall of the circumferential main groove is interconnected with the protruding end into the groove. The so-called see-through region that is sandwiched becomes considerably narrower than the groove width of the circumferential main groove, and therefore the wet performance, especially when the groove volume decreases at the end of wear, the wet performance is low. There was a problem.
[0004]
The present invention was made as a result of studying as a subject to solve such problems of the prior art, and the object of the present invention is to sufficiently provide excellent performance on ice and snow required for studless tires. In order to provide a heavy-duty pneumatic radial tire that achieves high wet performance.
[0005]
[Means for Solving the Problems]
The heavy-duty pneumatic radial tire according to the present invention is formed on the tread tread surface portion, and is formed between three or more circumferential main grooves extending linearly in the tread circumferential direction, between the circumferential main grooves. At least one circumferential narrow groove that continuously extends in a zigzag shape in the circumferential direction, a widthwise groove that extends in the tread width direction and that divides the land portion partitioned by each circumferential groove into blocks, and It is formed in each block, which even those comprising a respective sipe tends to extend in the tread width direction, the width of the circumferential main groove beyond the 5mm and the following dimensions 15 mm, also, the circumferential The width of the direction narrow groove is set to 2 mm or more and less than 5 mm , and two sipes are formed in each block, and one end of each of the two sipes is opened to the block side end opposite to each other. With it The other end is terminated in a block of, also characterized in that the shoulder side of the circumferential direction main groove to form a stepped rib which forms a step down relative to the tread surface of the cross-sectional contour is there.
[0006]
In pneumatic tires, it is effective to increase the edge component in the tread width direction by using circumferential grooves as zigzag grooves to ensure traction performance on snow. To ensure wet performance, circumferential grooves are straight grooves. It is advantageous to increase the see-through area, but especially with regard to wet performance, the effect is small when the groove width of the circumferential groove is narrow, while the effect on snow performance is also effective even when the groove width is narrow. Based on the new knowledge that this can be achieved, the pneumatic tire of the present invention has excellent wet performance by extending the circumferential main groove linearly and making the groove width wider than 5 mm. In addition, by extending circumferential narrow grooves of less than 5mm in a zigzag shape, excellent traction performance on snow is guaranteed.
[0007]
Here, when the groove width of the circumferential main groove is 5 mm or less, it is difficult to ensure high wet performance, and when the groove width of the circumferential narrow groove is 5 mm or more, the performance on snow is improved. Although there is no change, a decrease in performance on ice due to a decrease in the contact area is inevitable.
By the way, the lower limit value of the circumferential narrow groove is preferably 2 mm in order to prevent snow clogging there.
[0008]
Fig. 1 is a graph showing these points, and the braking distance from a vehicle speed of 80 km / h to stopping when a heavy-duty vehicle with a 2D axle is attached to a tire with tires with only circumferential grooves attached. By measuring the wet braking performance, and by measuring the braking distance from the vehicle speed of 20 km / h to the stop, the braking performance on snow was obtained, and the measured values were evaluated by an index.
[0009]
1 (a) and 1 (b) are graphs of zigzag grooves and linear grooves each having a swing width of 8 mm, with the groove width as a parameter, and the results are better as the index value is larger. It was.
[0010]
Here, according to FIG. 1 (a), the wet braking performance is greatly improved particularly in a straight groove having a groove width exceeding 5 mm, and according to FIG. 1 (b), the snow braking performance is It is clear that the zigzag grooves show particularly good results regardless of the width of the grooves.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 2 is a developed view of a tread pattern showing one embodiment of the present invention. Note that the internal reinforcement structure of the tire is the same as that of a general heavy-duty radial tire, and thus illustration thereof is omitted.
[0012]
Here, three circumferential main grooves 1 and 2 each having a groove width exceeding 5 mm and continuously extending linearly in the tread circumferential direction are provided on the tread surface, respectively, so that one circumferential main groove 1 is formed. On the tread center, the other two circumferential main grooves 2 are respectively positioned on the tread shoulder portion.
[0013]
Further, here, each circumferential narrow groove 3 extending in a zigzag shape in the tread circumferential direction and having a groove width of less than 5 mm, preferably 2 mm or more is formed between the circumferential main grooves 1 and 2. Each of the land grooves defined by the circumferential grooves 1, 2, 3 extends in the tread width direction and opens in the circumferential grooves 1, 2, 3. 6 is divided into respective blocks 7, 8, and 9, and each block 7, 8, 9 is formed with two sipes 11, 12, 13 that also tend to extend in the tread width direction. Thus, one end of each of the two sipes 11, 12, 13 is opened to the block side end opposite to each other, and the other end thereof is terminated in the block.
[0014]
By the way, reference numeral 14 in the figure denotes a step rib formed in the circumferential main groove 2 on the shoulder side and stepping down with respect to the cross-sectional outline of the tread surface. This step rib 14 is a load acting on the tire. It functions to contain uneven wear that inevitably occurs on the tire tread, locally and without affecting the tire performance.
[0015]
According to the tire configured as described above, excellent wet performance can be provided mainly under the action of the circumferential main grooves 1 and 2, and the tread width of each of the blocks 7, 8, and 9 can be provided. Excellent traction performance and braking performance on snow can be realized based on the action of the circumferential narrow grooves 3 in addition to the action of the peripheral edges and the sipes 11, 12, and 13 of the direction.
[0016]
【Example】
Examples of the present invention will be described below.
Each tire of size 11R 22.5 is attached to a heavy-duty vehicle with 2D axle type, and each vehicle is measured by measuring the braking distance from the vehicle speed of 80km / h to stopping under the load on the vehicle. The wet performance of the tire was determined, and the performance on snow was determined by measuring the braking distance on the snow from the vehicle speed of 20km / h to the stop, and the measured values were evaluated as shown in Table 1. became.
It should be noted that the larger the index value, the better the result.
[0017]
By the way, in the example tires in the table, the tires having the tread pattern shown in FIG. 2 are given various dimensions in the table, and both the conventional tire and the comparative tire have zigzag grooves in the circumferential main grooves. In addition, various dimensions in the table were given.
[0018]
[Table 1]

[0019]
According to Table 1, it is clear that in the example tire, both the wet performance and the performance on snow are greatly improved as compared with the conventional tire.
Further, in the comparative tire, the wet performance can be somewhat higher than that of the conventional tire due to the presence of the circumferential narrow groove. In particular, in the comparative tire 1, the circumferential narrow groove is a straight groove, so that the performance on snow is improved. It turns out that improvement cannot be realized.
[0020]
【The invention's effect】
As is apparent from the above description, according to the present invention, wet performance can be greatly improved while ensuring high performance on snow.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between groove width, wet braking performance, and snow braking performance of straight grooves and zigzag grooves.
FIG. 2 is a development view of a tread pattern showing an embodiment of the present invention.
[Explanation of symbols]
1, 2 circumferential main groove 3 circumferential narrow groove 4, 5, 6 width direction groove 7, 8, 9 block
11, 12, 13 Sipe
14 Step rib

Claims (1)

Three or more circumferential main grooves formed on the tread tread surface and extending linearly in the tread circumferential direction, and at least one circumferential direction formed between the circumferential main grooves and extending in a zigzag manner in the tread circumferential direction A narrow groove, a width direction groove that tends to extend in the tread width direction and divides the land portion divided by each circumferential groove into blocks, and a sipe that is formed in each block and tends to extend in the tread width direction A pneumatic tire with
Wherein the circumferential main groove width dimension below 15 mm beyond 5mm of, the width of the circumferential narrow groove, and less than 2mm or 5mm, formed by two of the sipes in each block, these two One end of each sipe is opened to the opposite block side end, and the other end is terminated in the block, and the cross-sectional profile of the tread tread is in the circumferential main groove on the shoulder side. A pneumatic radial tire for heavy loads, characterized by forming step ribs that step down with respect to the wire .

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