JP4955860B2 - Pneumatic tire - Google Patents

Description

【００２７】
テストの結果、実施例のタイヤにあっては、ウエット性能（新品時及び５０％摩耗時）、耐摩耗性能をバランス良く向上していることが確認できる。これに対して、比較例１、２では、ウエット性能は良好であるが、ブロック欠け又はヒール＆トウ摩耗が激しく、耐摩耗性の面で問題がある。また比較例３では、耐摩耗性能は比較的良好であったが、ウエット性能が著しく低いことが確認できる。
【００２８】
【発明の効果】
上述したように、本発明の空気入りタイヤは、タイヤ新品時では横溝の第１の屈曲部の折れ曲がり角度を一定範囲に限定することにより、該第１の屈曲部に面する陸部に形成されるエッジの効果でウエット性能を向上しうる。また５０％摩耗時には第１の屈曲部の折れ曲がり角度を小とすることにより、該第１の屈曲部に面する陸部の剛性を増し、ブロック欠けや偏摩耗の発生を防止できる。このように本発明の空気入りタイヤは、ウエット性能と耐摩耗性能とをバランス良く向上することができる。
【００２９】
また本発明では、横溝に第２の屈曲部を設け、この屈曲部についても第１の屈曲部と同様に折れ曲がり角度を設定しているため、よりウエット性能と耐摩耗性能とをバランス良く向上しうる。
【００３０】
さらに、本発明では、溝巾が１５mm以上と太い重荷重用タイヤに適用されるため、本発明の効果がより顕著に発揮されうる。
【図面の簡単な説明】
【図１】本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。
【図２】そのトレッド面での横溝の拡大図である。
【図３】トレッド部の断面略図である。
【図４】５０％摩耗時の状態を示すトレッドパターンの展開図である。
【図５】そのトレッド面での横溝の拡大図である。
【図６】溝底縁までを示す図５の拡大図である。
【図７】ブロックの部分斜視図である。
【図８】比較例３のトレッドパターンを示す平面図である。
【図９】従来の横溝を示す平面図である。
【符号の説明】
２ トレッド面
３ 横溝
３ａ 第１の部分
３ｂ 第２の部分
３ｃ 第３の部分
５ 第１の屈曲部
６ 第２の屈曲部
θａ0 新品時の第１の屈曲部の折れ曲がり角度
θａ50 ５０％摩耗時の第１の屈曲部の折れ曲がり角度
θｂ0 新品時の第２の屈曲部の折れ曲がり角度
θｂ50 ５０％摩耗時の第２の屈曲部の折れ曲がり角度[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire that can improve wet performance and wear resistance performance in a well-balanced manner.
[0002]
[Prior art and problems to be solved by the invention]
Conventionally, a tread surface of a pneumatic tire is provided with a lateral groove extending in the tire axial direction in order to improve traction performance. In particular, in a heavy-duty tire used for heavy-duty vehicles such as trucks and dump trucks, such lateral grooves are frequently used as lug grooves as shown in FIG.
[0003]
However, a pattern that mainly includes lateral grooves generally tends to have low wet performance. For this reason, conventionally, as shown in FIG. 9, it is formed in a zigzag shape by providing a bent portion b in the lateral groove a, and the wet performance is improved by a draining effect using the edge e of the land portion facing the bent portion b. Is planned. However, such a zigzag lateral groove a tends to easily cause chipping of a land portion starting from the edge e or uneven wear (for example, heel & toe wear) starting from the edge e as wear progresses. There is.
[0004]
The present invention has been devised in view of such a situation, and is based on the principle that the angle of the bent portion of the lateral groove is large when the tire is new and small when 50% is worn. An object of the present invention is to provide a pneumatic tire capable of improving the wear performance in a well-balanced manner.
[0005]
[Means for Solving the Problems]
The invention according to claim 1 of the present invention is a pneumatic tire in which a lateral groove is provided on a tread surface, and the lateral groove has a lateral groove centerline passing through the middle between the groove edges on the road surface and the tread surface that contacts the road surface. A first portion extending at an angle θ1 with respect to the tire axial direction, and a second portion extending to the first portion and extending at an angle θ2 (≠ θ1) with respect to the tire axial direction. When the tire is new, the bending angle θa0 of the first bending portion represented by | θ2−θ1 | is 30 to 50 °, and the first bending portion is 50% worn. The bend angle θa50 is 0.35 to 0.65 times the θa0.
[0006]
In the present invention, the transverse grooves may have a second bent portion by the arc and a third portion extending in said second portion contiguous and angle θ3 with respect to the tire axial direction (≠ .theta.2), When the tire is new, the bending angle θb0 of the second bent portion represented by | θ3−θ2 | is set to 30 to 50 °, and the bending angle θb50 of the second bent portion at the time of 50% wear is set to the it characterized in that it was 0.35-0.65 times of θb0.
[0007]
Further, the present invention, the lateral grooves, is empty pneumatic tire of a heavy duty groove width is 15~25mm.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a development view (when new) of a tread pattern of a heavy-duty pneumatic tire mounted on a truck, a bus, or the like as this embodiment, and FIG. 2 is a partially enlarged view of the lateral groove 3. Moreover, the horizontal groove of FIG. 1, FIG. 2 patterns the groove edge in the tread surface which contacts a road surface. As shown in FIG. 1, a lateral groove 3 is provided on the tread surface 2. In the present example, the lateral groove 3 is formed in a lug groove shape that extends inward in the tire axial direction from the tread ends E on both sides.
[0009]
Lateral grooves 3 of the groove width, groove depth, 5.0 to 12.0% of the good Mashiku tread width of the groove width, more preferably between 6.0 to 10.5%, the groove depth of the tread width It is desirable that the content be 8.0 to 10.5%, more preferably 8.5 to 10.0%. If the groove width is less than 5.0% of the tread width or the groove depth is less than 8.0%, the wet performance tends to deteriorate because the basic drainage performance is deteriorated. If the width is larger than 12.0% or the groove depth is larger than 10.5% of the tread width, the rigidity of the tread surface 2 tends to be lowered, and the driving stability and grip force on the dry pavement are impaired. Cheap. Particularly as in the present invention, in the case of tires for heavy load, to set the lateral groove 3 of the groove width at 15 to 25 mm.
[0010]
The tread width refers to the distance in the tire axial direction between the grounded outer ends when the tire is assembled on a regular rim, filled with a regular internal pressure, and loaded with a regular load and brought into contact with a flat surface. The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, a standard rim for JATMA, “Design Rim” for TRA, or ETRTO If so, use "Measuring Rim". In addition, “regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. It is the maximum air pressure for JATMA and the table “TIRE LOAD LIMITS” for TRA. The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for ETRTO, but 180 KPa for tires for passenger cars. Furthermore, “regular load” is the load that each standard defines for each tire in the standard system including the standard on which the tire is based. The maximum load capacity is specified for JATMA, and the table “TIRE LOAD LIMITS” for TRA. The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”. If ETRTO, “LOAD CAPACITY”.
[0011]
In this example, the lateral groove 3 has a first portion 3a, one end of which is continuous with the tread end E and linearly extending at an angle θ1 with respect to the tire axial direction N, and the first portion 3a, which is continuous with the first portion 3a. A second portion 3b extending linearly with respect to N at an angle θ2 (≠ θ1), and a second portion 3b extending linearly with respect to the tire axial direction N at an angle θ3 (≠ θ2). 3 portion 3c. Accordingly, the lateral groove 3 has a first bent portion 5 bent at an angle | θ2-θ1 | and a second bent portion 6 bent at an angle | θ3-θ2 |. The zigzag shape extends in the tire axial direction. It is The angles θ1 to θ3 of the respective portions 3a to 3c of the lateral groove 3 can be determined by the lateral groove center line CL passing through the middle between the groove edges 7 and 7 of the lateral groove 3. In the present specification, in the angles θ1 to θ3, the counterclockwise direction is positive and the clockwise direction is negative with respect to the tire axial direction N.
[0012]
The tread surface 2 is provided with a pair of zigzag narrow grooves 4a, 4a that are zigzag-shaped and extend in the tire circumferential direction on both sides of the tire equator. The zigzag narrow groove 4a extends continuously in the tire circumferential direction while joining the inner end side in the tire axial direction of the third portion 3c of the lateral groove 3. In the present embodiment, the zigzag narrow groove 4a is slanted in one direction with respect to the tire circumferential direction and extends in a straight line, and the slanted groove 4a is slanted and straight in a direction opposite to the narrow width part 4a1 with respect to the tire circumferential direction. The wide portions 4a2 extending in a shape are arranged alternately in the tire circumferential direction. This helps to form a zigzag edge continuously in the circumferential direction of the tire to compensate for improved wet performance. The groove width of the zigzag narrow groove 4a is not particularly limited, but is smaller than the groove width of the lateral groove 3 in this example. Specifically, the narrow portion 4a1 is, for example, 2.5 to 4.5 mm, and the wide portion 4a2 is 1.0 to 3.0 times, more preferably 1.0 to 2.5 times that of the narrow portion 4a1. It is desirable to set the groove width.
[0013]
Further, the zigzag narrow groove 4a is formed on the tread surface 2 by extending between the lateral grooves 3 and 3 adjacent to each other in the tire circumferential direction and connecting the first bent portion 5 and the second bent portion 6 of these lateral grooves 3. An oblique narrow groove 4b extending linearly in parallel with the narrow width portion 4a1 is provided. The slanted narrow groove 4b is set to have a small width of, for example, a groove width of 1.0 to 4.0 mm, more preferably 1.0 to 3.0 mm. Such slanted narrow grooves 4b do not contribute much to the improvement of drainage, but optimize the rigidity of the land portion between the lateral grooves 3 and 3 to alleviate the shear force generated between the road surface and the like during turning. In addition to being able to contribute to the improvement of wear resistance, the rigidity of the land portion is secured by easily closing the groove width, so that it is possible to prevent a decrease in steering stability performance. The angle α of the narrow portion 4a1 of the zigzag narrow groove 4a and the slanted narrow groove 4b with respect to the tire circumferential direction is preferably 16 to 30 °, more preferably 22 to 27 °.
[0014]
Further, on the tread surface 2, a joint groove 4c extending between the pair of zigzag narrow grooves 4a, 4a and bent in a substantially Z shape is provided in the tire circumferential direction. As a result, the tread surface 2 of the present example has a large center block B1 having a substantially S shape in plan view aligned in the tire circumferential direction between the zigzag narrow grooves 4a, 4a, and the zigzag narrow groove 4a. A substantially hexagonal middle block B2 formed between the narrow groove 4b and a substantially hexagonal shoulder block B3 formed on the outer side in the tire axial direction of the slanted narrow groove 4b are formed.
[0015]
As shown in FIG. 2, when the tire is new, the pneumatic tire has a second bending angle θa 0 and | θ 3 −θ 2 | of the first bending portion 5 represented by | θ 2 −θ 1 |. The bending angle θb0 of the bent portion 6 is set to 30 to 50 °, and is set relatively large. As a result, sharp edges e are formed in the land portions (in this example, the middle block B2 and the shoulder block B3) located in the front and rear in the tire circumferential direction with the first and second bent portions 5 and 6 interposed therebetween. Such an edge e can cut and eliminate the water film at the time of contact with the road surface having the water film, thereby improving the wet performance.
[0016]
If the bending angle θa0 of the first bent portion 5 is less than 30 °, the effect of improving the wet performance cannot be sufficiently obtained. Conversely, if it exceeds 50 °, the edge e becomes excessively sharp and its rigidity is lowered. to reason, in addition to easily chipped occurs the edge e, uneven wear of said heel and toe wear decreases the like abrasion resistance tends to occur. More preferably, the bending angle θa0 of the first bent portion 5 is 34.0 to 46.0 °. Further, the second bent portion 6 is not particularly limited, but in the present embodiment, similarly to the first bent portion 5, the bending angle θb0 of the second bent portion 6 is also limited to 30 to 50 °. is doing. Thereby, the land part which has more edges e can be formed in the tread surface 2, and wet performance can further be improved.
[0017]
In the pneumatic tire of the present invention, the first bent portion 5 is set such that the bending angle θa50 at the time of 50% wear is 0.35 to 0.65 times the bending angle θa0 when new. In addition, in this example, the bending angle θb50 at the time of 50% wear is also set to 0.35 to 0.65 times the bending angle θb0 at the time of new article for the second bent portion 6. Here, “at the time of 50% wear” means, as shown in FIG. 3, the depth of the lateral groove 3 (maximum groove depth) by cutting the tread portion along a curved surface P parallel to the tread surface 2 at the time of a new article. (Specified by the part) is set to a state where 50% of the new item is set.
[0018]
4 is a developed view of a tread pattern of a pneumatic tire at 50% wear, FIG. 5 is an enlarged plan view of the lateral groove 3, FIG. 6 is a plan view up to the groove bottom edge, and FIG. 7 is blocks B2 and B3. Are respectively perspective views. As shown in FIGS. 5 and 6, in this embodiment, the groove edge 7 and the groove bottom edge 9 of the lateral groove 3 are set non-parallel. Thereby, each groove wall surface W1, W2,... Of the lateral groove 3 is formed not by a plane but by a twisted curved surface. The groove wall surfaces W1, W2,... Are set so that the bending angles θa, θb of the first and second bent portions 5, 6 gradually decrease as the tread surface 2 wears. ing.
[0019]
First and second bent parts 5 and 6, angle bending that is at 50% wear θa50, θb50 is bent at the time of a new angle Shitaei0, by becoming smaller than Shitabi0, first and second bent as wear The rigidity in the vicinity of each edge e of the middle block B2 and the shoulder block B3 facing the portions 5 and 6 can be increased. For this reason, it is possible to suppress the occurrence of heel & toe wear starting from the edge e accompanying the progress of wear, and at the same time, it is possible to prevent the chipping of the block by making the edge e of the block non-sharp.
[0020]
If the bending angle θa50 of the first bent portion 5 at the time of 50% wear is less than 0.35 times the bending angle θa0 at the time of a new article, it is advantageous for wear resistance performance, but the edge action is reduced. The wet performance is significantly reduced. Further, when the bending angle θa50 of the first bent portion 5 at the time of 50% wear exceeds 0.65 times the bent angle θa0 at the time of a new product, it is advantageous for wet performance, but the first bent portion 5 The distortion tends to concentrate on the facing block or the edge e of the land part, and the chipping of the block and heel & toe wear are likely to be caused and the wear resistance is deteriorated. From this point of view, it is particularly desirable for the first bent portion 5 to set the bending angle θa50 at the time of 50% wear to 0.40 to 0.60 times the bending angle θa0 at the time of a new product. The same applies to the second bent portion 6.
[0021]
Although the embodiments of the present invention have been described above, the present invention is not limited to the illustrated heavy load tires as long as the tire has a lateral groove extending in the tire axial direction, and can be applied to various categories of tires. . Further, the tread pattern can be applied to various patterns such as a lag pattern and a rib lag pattern in addition to the block-based pattern as in this example. Furthermore, lateral grooves 3 in the present embodiment, first, showed that comprises the second bending portions 5 and 6, the present invention is applied to such transverse groove which comprises a third bending portion to be al it can.
[0022]
【Example】
Four types of heavy-duty radial tires with a tire size of 11R22.5 were prototyped, and wet performance (when new and 50% worn), presence or absence of land chipping, and heel & toe wear were measured. All of the prototype tires have the same internal structure and differ only in the tread pattern. The embodiment has the tread pattern shown in FIG. 1 and FIG. 3, and Comparative Example 1 is the same as FIG. 1 when it is new, but the bending angle of the bent portion substantially changes even when 50% wears. In the comparative example 2, the first and second bent portions have a large bending angle, and the comparative example 3 is generally used conventionally as shown in FIG. It has a rug pattern. The test conditions are as follows.
[0023]
<Wet performance test>
The test tire is assembled on a rim (7.50 × 22.5) and filled with an internal pressure of 850 kPa, and it is mounted on two driving wheels of a 2-D truck with a constant load (10 liters). The maximum traction force at the moment when the driving wheel slips on a low μ road such as above was measured. Generally, since the maximum traction force on a low μ road of a new tire requested by a user is 15 kN, the evaluation is represented by an index with 15 kN as 100. It shows that it is so favorable that a numerical value is large. The test at the time of 50% wear was carried out after cutting a new tire into a 50% wear state and running-in for 500 km.
[0024]
<Land part missing test>
The test tire is assembled on a rim (7.50 x 22.5) and filled with an internal pressure of 850 kPa, and is mounted on two wheels of a 2-D truck with a constant load (10 liters). The road test was conducted until the thickness became substantially 50%. And the number which the chip | tip has produced in the edge of the block facing the 1st, 2nd bending part was measured. The smaller the number, the better.
[0025]
<Heel & toe wear test>
The road test was performed until the depth of the lateral groove was substantially 30% under the vehicle conditions. And the heel & toe wear amount was measured about the block which faced the horizontal groove. Those with a heel & toe wear amount of 3 mm or less are inconspicuous in appearance and pass.
The test results are shown in Table 1.
[0026]
[Table 1]

[0027]
As a result of the test, it can be confirmed that in the tire of the example, the wet performance (when new and 50% worn) and the wear resistance are improved in a well-balanced manner. On the other hand, in Comparative Examples 1 and 2, the wet performance is good, but block chipping or heel & toe wear is severe, and there is a problem in terms of wear resistance. In Comparative Example 3, the wear resistance was relatively good, but it was confirmed that the wet performance was extremely low.
[0028]
【Effect of the invention】
As described above, the pneumatic tire of the present invention is formed in a land portion facing the first bent portion by limiting the bending angle of the first bent portion of the lateral groove to a certain range when the tire is new. The wet performance can be improved by the edge effect. Further, by reducing the bending angle of the first bent portion at the time of 50% wear, the rigidity of the land portion facing the first bent portion can be increased, and the occurrence of block chipping and uneven wear can be prevented. Thus, the pneumatic tire of the present invention can improve wet performance and wear resistance performance in a well-balanced manner.
[0029]
In the present invention, the second bent portion is provided in the lateral groove, and the bent angle is set for the bent portion in the same manner as the first bent portion, so that the wet performance and the wear resistance performance are improved in a balanced manner. sell.
[0030]
Furthermore, since the present invention is applied to heavy duty tires having a groove width of 15 mm or more, the effects of the present invention can be more remarkably exhibited.
[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 an enlarged view of a lateral groove on the tread surface.
FIG. 3 is a schematic cross-sectional view of a tread portion.
FIG. 4 is a development view of a tread pattern showing a state at the time of 50% wear.
FIG. 5 is an enlarged view of a lateral groove on the tread surface.
6 is an enlarged view of FIG. 5 showing a groove bottom edge. FIG.
FIG. 7 is a partial perspective view of a block.
8 is a plan view showing a tread pattern of Comparative Example 3. FIG.
FIG. 9 is a plan view showing a conventional lateral groove.
[Explanation of symbols]
2 Tread surface 3 Horizontal groove 3a 1st portion 3b 2nd portion 3c 3rd portion 5 1st bent portion 6 2nd bent portion θa0 Bending angle of first bent portion when new, θa50 50% when worn Bending angle of the first bent portion θb0 Bending angle of the second bent portion at the time of a new product θb50 Bending angle of the second bent portion at 50% wear

Claims (1)

A pneumatic tire provided with a lateral groove on the tread surface,
The transverse groove includes a first portion in which a transverse groove center line passing through the middle between the groove edges on the tread surface that contacts the road surface extends at an angle θ1 with respect to the tire axial direction, and is connected to the first portion. A first bent portion by including a second portion extending at an angle θ2 (≠ θ1) with respect to the direction,
When the tire is new, the bending angle θa0 of the first bent portion represented by | θ2−θ1 | is set to 30 to 50 °,
And the bending angle θa50 of the first bent portion at the time of 50% wear is 0.35 to 0.65 times the θa0 ,
The lateral groove has a second bent portion by including a third portion that continues to the second portion and extends at an angle θ3 (≠ θ2) with respect to the tire axial direction.
When the tire is new, the bending angle θb0 of the second bent portion represented by | θ3-θ2 | is set to 30 to 50 °,
And the bending angle θb50 of the second bent portion at the time of 50% wear is 0.35 to 0.65 times the θb0,
The horizontal groove has a groove width of 15 to 25 mm, and is a pneumatic tire for heavy loads .

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