JP3636811B2 - Pneumatic tire - Google Patents

Description

【００３９】
上記試験結果から、本発明の実施例の空気入りタイヤが従来の空気入りタイヤ及び比較例タイヤに比較して氷雪性能に優れていることが明確になった。
【００４０】
また、実施例タイヤ３は、サイプ本数を従来よりも増したにもかかわらずブロック剛性が殆ど低下しなかったため、氷雪性能が大幅に向上した。
【００４１】
なお、上記実施形態では、サイプの形状がジグザグ状であったが、サイプはその他の形状、例えば、波形状であっても良い。
【００４２】
また、サイプの方向は実質的にタイヤ軸方向に延びていれば良く、タイヤ軸方向に傾斜していても良い。
【００４３】
また、上記実施形態では、トラック用のタイヤに本発明を適用した例を示したが、本発明は、バス、乗用車等の他の車両用のタイヤに適用しても良いのは勿論である。
【００４４】
【発明の効果】
以上説明したように、請求項１に記載の空気入りタイヤは上記の構成としたので、耐摩耗性、耐偏摩耗性等の他性能を低下させることなく高い氷雪性能を得ることができるという優れた効果を有する。耐摩耗性、耐偏摩耗性が特に低いブロック列に底上げサイプを配置することにより、有効に最小限のブロック剛性の向上ができる。
【００４５】
請求項２に記載の空気入りタイヤは上記の構成としたので、エッジ効果が周方向及び軸方向に発揮され、氷雪路走行に好適となる。
【００４６】
請求項３に記載の空気入りタイヤは上記の構成としたので、高い氷雪性能を確実に得られ、また、耐摩耗性、耐偏摩耗性の低下を確実に防止できるという優れた効果を有する。
【００４７】
請求項４に記載の空気入りタイヤは上記の構成としたので、ブロックのタイヤ周方向の剛性をタイヤ軸方向により一層均一に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】本発明の一実施形態に係る空気入りタイヤのトレッドの平面図である。
【図２】図１に示すブロックの拡大平面図である。
【図３】図２に示すブロックの３−３線断面図である。
【図４】トラクション・ブレーキ入力が作用した際の変形状態を示すブロックの断面図である。
【図５】他の実施形態に係る空気入りタイヤのブロックの平面図である。
【図６】従来タイヤのブロックの平面図である。
【図７】トラクション・ブレーキ入力が作用した際の図６に示すブロックの断面図である。
【符号の説明】
１２ トレッド
１８ ブロック
２０Ａ サイプ
２０Ｂ サイプ
２２ 底上げ部分[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire that is particularly excellent in running performance on icy and snowy roads.
[0002]
[Prior art]
As the use of spike tires has been banned, various tread improvements have been made in search of better studless tires. A tread of a studless tire that runs on ice and snow is provided with a plurality of circumferentially extending main grooves and blocks (land portions) that are distinguished by a number of lug grooves that intersect with these main grooves. Sipes are provided.
[0003]
In order to improve the snow and snow performance, it is known that increasing the edge component by sipe is effective.
[0004]
[Problems to be solved by the invention]
However, the increase in edge components due to an increase in the number of sipes has a limit due to a decrease in block rigidity.
[0005]
In other words, if a large number of sipes are provided in the block in order to improve the snow and snow performance, the edge component increases, but the block rigidity decreases, and the land element segmented by the sipes collapses. As a result, the ground contact property is lowered, the snow and snow performance is lowered, the wear resistance and uneven wear resistance (occurrence of heel and toe wear), the block durability is lowered, and the like.
[0006]
In order to solve this problem, as shown in FIG. 6, a bottom-up portion 22 (a portion surrounded by a dotted line) with a shallow sipe depth is provided at the ends and the center of the sipes 20A and 20B. Although measures have been taken to reinforce and prevent the fall of the divided land element 23, there is a limit to the increase in the number of sipes.
[0007]
In view of the above facts, an object of the present invention is to provide a pneumatic tire capable of obtaining high ice / snow performance without lowering other performances such as wear resistance and uneven wear resistance.
[0008]
[Means for Solving the Problems]
As a result of the inventors investigating and examining the conventional tire, in the conventional tire, the sipe reinforcement by the bottom-up portion 22 is arranged at the end portion or the center portion of each sipe, so that the reinforcement unevenness is large, and the tire circumferential direction Since the ratio of the projected length (L1 + L2 + L3) projected in the tire circumferential direction of the bottom-up portion 22 to the tire axial direction dimension WB of the block 18 projected on is as low as 30% to 50%, the tire circumferential direction input, that is, It was found that sufficient reinforcement effect was not obtained with respect to stepping in, kicking out input, traction brake input.
[0009]
The invention described in claim 1 has been made in view of the above-described facts, and is a pneumatic tire having a plurality of rows of blocks arranged in the tire circumferential direction on the tread , the depth of which is reduced. A block having at least one row of blocks each including a plurality of bottom-up sipes having a bottom-up portion and extending substantially in the tire axial direction, the block having the bottom-up sipes. The bottom raised portion is straight in the tire circumferential direction in at least one of the remaining regions excluding the tire axial end region of the block from a plurality of regions passing through the bottom raised portion in the tire circumferential direction. It is characterized by not being lined up on the line.
[0010]
Next, the operation of the pneumatic tire according to claim 1 will be described.
By arranging bottom-up sipes extending substantially in the tire axial direction along the tire circumferential direction, a plurality of land elements are formed in the block, and at the same time, an edge effect is ensured.
[0011]
In addition, if the block is divided into a plurality of blocks, the rigidity of the block decreases, so the land elements between the sipes are likely to fall down during driving and braking, and the actual ground contact area decreases. However, the raised part of the raised sipe increases the rigidity. Therefore, the land element can be prevented from falling. Moreover, in the present invention, at least one of the remaining regions excluding the region at the tire axial direction end of the block from the plurality of regions passing through the bottom-up portion in the tire circumferential direction, the bottom-up portion is disposed in the tire circumferential direction. Since the bottom-up portions are dispersed in the tire circumferential direction, the rigidity of the block in the tire circumferential direction can be made uniform in the tire axial direction.
[0012]
For this reason, the fall of the land element subdivided by the sipe can be uniformly suppressed as a whole, and high snow and ice performance can be ensured by improving the ground contact property uniformly. Further, since the ground contact property is improved uniformly, the wear resistance and uneven wear resistance are also improved. When the conventional simple siping as shown in FIG. 6 is applied to the block row in the tread pattern having a plurality of block rows in which the blocks are arranged along the tire circumferential direction, the entire applied block row is as described above. However, in the pneumatic tire according to claim 1, since the bottom-up sipes are formed in all the blocks in at least one block row, the present invention is more effective. The function of bottom-up siping can be demonstrated.
[0013]
The invention according to claim 2 is the pneumatic tire according to claim 1, wherein the sipe has a zigzag shape.
[0014]
Next, the operation of the pneumatic tire according to claim 2 will be described.
In the pneumatic tire according to claim 2, since the sipe extends in a zigzag shape, the edge effect is exhibited in the circumferential direction and the axial direction, which is suitable for running on an icy and snowy road.
[0015]
According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, the bottom raised portion projected in the tire circumferential direction with respect to the tire axial dimension of the block projected in the tire circumferential direction. The projected length is at least 60%.
[0016]
Next, the operation of the pneumatic tire according to claim 3 will be described.
In the pneumatic tire according to claim 3, since the projected length of the raised portion projected in the tire circumferential direction with respect to the tire axial direction dimension of the block projected in the tire circumferential direction is within the range of at least 60%, High ice and snow performance can be reliably obtained. In addition, it is possible to reliably prevent the wear resistance and uneven wear resistance from decreasing.
[0017]
In addition, if the throwing length is less than 60% in the tire circumferential direction with respect to the tire axial direction dimension of the block projected in the tire circumferential direction, a difference from the conventional tire cannot be obtained.
[0018]
According to a fourth aspect of the present invention, in the pneumatic tire according to any one of the first to third aspects, each bottom raised portion of each bottom raised sipe is set to 1 in the tire axial direction in the arrangement order of the bottom raised sipe. It is characterized by being sequentially shifted in the direction.
[0019]
Next, the operation of the pneumatic tire according to claim 4 will be described.
In the pneumatic tire according to claim 4, since each bottom raised portion of each bottom raised sipe is sequentially shifted in one direction in the tire axial direction in the order of arrangement of the bottom raised sipe, the rigidity in the tire circumferential direction of the block is determined by the tire axial direction. It can be made more uniform.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a pneumatic tire according to the present invention will be described below with reference to FIGS.
[0023]
As shown in FIG. 1, a block 18 defined by a plurality of circumferential main grooves 14 and a plurality of lug grooves 16 is provided on the tread 12 of the pneumatic tire (tire size: LXR 6.50R16 10PR) of the present embodiment. A plurality are provided. The tread 12 of this embodiment is provided with 240 (3 × 80 pitch) blocks 18.
[0024]
As shown in FIG. 2, the block 18 extends in a zigzag shape along the tire axial direction (arrow A direction) from one end 18 </ b> A facing one circumferential main groove 14 toward the other circumferential main groove 14. Two sipe 20A terminating at a predetermined dimension before the other circumferential main groove 14 are formed, and the tire shaft extends from one end 18B facing the other circumferential main groove 14 toward one circumferential main groove 14. A sipe 20B extending in the direction and ending before a predetermined dimension of one circumferential main groove 14 is formed between the sipe 20A and the sipe 20A.
[0025]
As for the dimensions of the block 18 of this embodiment, the dimension LB in the tire circumferential direction (arrow B direction) is 26 mm, the dimension WB in the tire axial direction is 21 mm, and the height HB is 14.4 mm as shown in FIG.
[0026]
As shown in FIG. 2, the length LS of the sipe 20A and the sipe 20B in the tire axial direction is 18 mm, and the sipe interval P is 5 mm. The sipe depths of the sipe 20A and the sipe 20B are not constant over the entire length, and the bottom-up portion 22 surrounded by the dotted line in FIG. 2 is shallower than the main region (region other than the bottom-up portion 22) as shown in FIG. Yes. In the sipe 20A and the sipe 20B, the sipe depth DM of the main region is 10.1 mm, and the sipe depth Ds of the bottom-up portion 22 is 7.2 mm.
[0027]
As shown in FIG. 2, the bottom-up portions 22 are provided one at each of the ends of the sipe 20 </ b> A and the sipe 20 </ b> B on the circumferential main groove 14 side and the portions separated from the ends, and the bottom-up portions 22 are provided at the center side. The portions 22 are sequentially provided while being shifted by a predetermined dimension in one direction so as not to overlap when projected in the tire circumferential direction.
[0028]
As shown in FIG. 2, in this embodiment, the projection length (L1 + L2 +... + L5) of the bottom raised portion 22 is 85% with respect to the length (dimension WB) of the block 18 projected in the tire circumferential direction. Is set.
[0029]
Next, the operation of this embodiment will be described.
In the pneumatic tire of the present embodiment, the bottom-up portion 22 of the sipe 20A, 20B increases the rigidity, so that the falling of the land element 23 divided by the sipe 20A, 20B with respect to the traction / brake input can be suppressed. . In addition, since the raised bottom portions 22 are arranged in the tire circumferential direction, the rigidity of the block 18 in the tire circumferential direction can be made uniform in the tire axial direction, and the falling of the land element 23 can be suppressed uniformly. As a result, the grounding property can be improved uniformly and high snow and ice performance can be secured.
[0030]
For example, when the conventional block 100 in which the bottom-up portion 22 is provided at the ends and the center of the sipes 20A and 20B as shown in FIG. 6 is compared with the block 18 of the present embodiment, the conventional block 100 is shown in FIG. 6 and FIG. 7, in the deep region of the sipe depth between the raised portion 22 and the raised portion 22, the land element 23 is greatly collapsed with respect to the traction / brake input, and the actual ground contact area is greatly reduced. In the block 18 of the present embodiment in which the bottom-up portions 22 are dispersed in the tire axial direction, as shown in FIG. 4, the land element 23 is less collapsed and the actual contact area is less decreased.
[0031]
Further, in the pneumatic tire according to the present embodiment, the rigidity in the tire circumferential direction of the block 18 approaches uniformly in the tire axial direction, so that the durability of the block can be improved. By improving uniformly, wear resistance and uneven wear resistance can also be improved.
[Test example]
In order to confirm the effect of the present invention, three types of example tires to which the present invention was applied, one conventional tire, and one comparative tire were prepared, and ice / snow resistance, wear resistance and uneven wear resistance were obtained by the following methods. Examined.
(Test method)
Ice and snow: A test tire is mounted on a real car (Toyota Dyna 2t product 2WD car) and suddenly braked (locked) while driving on an icy road at a speed of 20km / h, from that point to the stop point. The distance was measured.
[0032]
Abrasion resistance: A test tire was mounted on an actual vehicle (same as above), traveled on a predetermined course with a general road for 15,000 km, and the amount of wear was calculated by measuring the groove depth before and after traveling.
[0033]
Uneven wear resistance: The level difference due to heel and toe wear generated in the front and rear land portions of the lug groove of a tire that traveled in the same manner as the evaluation of wear resistance was measured.
[0034]
The structure of the conventional tire and the example tire used for the test will be described below.
Conventional tire: As shown in FIG. 6, one sipe 20B and two sipes 20A are formed on a block 18, and a bottom-up portion is provided at an end portion and a center portion surrounded by a dotted line, and a projection ratio (in the tire circumferential direction) This is a pneumatic tire in which the ratio (%) of the projected length of the bottom raised portion projected in the tire circumferential direction to the tire axial direction dimension of the projected block is 45%.
[0035]
Example tires 1 and 2 and comparative example tire 1: The number of sipes was the same as that of conventional tires, and the pneumatic tires were changed in projection ratio as shown in Table 1 below.
[0036]
Example tire 3: As shown in FIG. 5, a pneumatic tire having a projection ratio of 85% in which two sipes 20A and two sipes 20B are alternately formed, and bottom-up portions 22 shown by dotted lines as shown in the figure are arranged. It is.
[0037]
The sipe of each tire has the same length.
The results of the test are as shown in Table 1 below. The results are shown in index notation where the conventional tire is 100, and the larger the value, the better the performance.
[0038]
[Table 1]

[0039]
From the above test results, it became clear that the pneumatic tires of the examples of the present invention were superior in ice / snow performance compared to conventional pneumatic tires and comparative tires.
[0040]
In addition, since the block stiffness of the tire 3 of Example 3 did not substantially decrease despite the increase in the number of sipes than before, the snow and ice performance was greatly improved.
[0041]
In the above embodiment, the sipe has a zigzag shape, but the sipe may have another shape, for example, a wave shape.
[0042]
Further, the direction of the sipe may be substantially extended in the tire axial direction, and may be inclined in the tire axial direction.
[0043]
Moreover, although the example which applied this invention to the tire for trucks was shown in the said embodiment, of course, this invention may be applied to the tires for other vehicles, such as a bus and a passenger car.
[0044]
【The invention's effect】
As described above, since the pneumatic tire according to claim 1 has the above-described configuration, it is possible to obtain high snow and ice performance without reducing other performances such as wear resistance and uneven wear resistance. It has the effect. By arranging the bottom-up sipe in a block row having particularly low wear resistance and uneven wear resistance, the minimum block rigidity can be effectively improved.
[0045]
Since the pneumatic tire according to claim 2 has the above-described configuration, the edge effect is exhibited in the circumferential direction and the axial direction, and it is suitable for running on icy and snowy roads.
[0046]
Since the pneumatic tire according to claim 3 has the above-described configuration, it has an excellent effect that high ice and snow performance can be reliably obtained, and a decrease in wear resistance and uneven wear resistance can be surely prevented.
[0047]
Since the pneumatic tire according to claim 4 has the above-described configuration, it has an excellent effect that the rigidity in the tire circumferential direction of the block can be made more uniform in the tire axial direction.
[Brief description of the drawings]
FIG. 1 is a plan view of a tread of a pneumatic tire according to an embodiment of the present invention.
FIG. 2 is an enlarged plan view of the block shown in FIG.
3 is a sectional view of the block shown in FIG. 2 taken along line 3-3.
FIG. 4 is a sectional view of a block showing a deformed state when a traction brake input is applied.
FIG. 5 is a plan view of a block of a pneumatic tire according to another embodiment.
FIG. 6 is a plan view of a block of a conventional tire.
7 is a cross-sectional view of the block shown in FIG. 6 when a traction brake input is applied.
[Explanation of symbols]
12 Tread 18 Block 20A Sipe 20B Sipe 22 Bottom-up part

Claims (4)

A pneumatic tire having a plurality of rows of blocks arranged in the tire circumferential direction on the tread .
A plurality of bottom-up sipes having a bottom-up portion having a shallow depth and extending substantially in the tire axial direction, and at least one block row comprising the blocks arranged along the tire circumferential direction;
In the block having the bottom raising sipes, the bottom raising is performed in at least one of the remaining areas excluding the area in the tire axial direction end of the block from the plurality of areas passing through the bottom raising portion in the tire circumferential direction. A pneumatic tire characterized in that the portions are not arranged in a straight line in the tire circumferential direction.   The pneumatic tire according to claim 1, wherein the sipe has a zigzag shape.   The projected length of the bottom-up portion projected in the tire circumferential direction with respect to the tire axial direction dimension of the block projected in the tire circumferential direction is set to at least 60%. Pneumatic tire.   The pneumatic tire according to any one of claims 1 to 3, wherein each bottom raised portion of each bottom raised sipe is sequentially shifted in one direction in the tire axial direction in the order of arrangement of the bottom raised sipe.

Images