JP4141017B2 - Pneumatic tire - Google Patents

Description

本発明の適用された第１実施例〜第８実施例のタイヤは、従来例のタイヤに対して操縦安定性能が向上しているのが分かる。
【００９８】
また、最も評価の高かった第４実施例のタイヤについて、接地圧力の評価を行ったのが以下の表２，３である。
【００９９】
【表２】

【０１００】
【表３】

なお、この時考慮した入力条件及びその番号を図５に示す。
【０１０１】
入力１は、平押し荷重条件（面圧４kgf/cm² 相当）、入力２〜８は、図５に示す方向への剪断入力（剪断変形量１mmで評価）である。
【０１０２】
表２では、ブロック踏面の接地圧均一の度合いを指数で各入力毎に示している。結果は接地圧の不均一を、接地領域における接地圧の標準偏差で平均４５％改良している。
【０１０３】
また、このブロックの接地領域の面積を各入力ごとに示した表３は、上記改良が接地面積を損なわずになされたことを示し、他性能への悪影響を及ぼしにくいことが示唆される。
【０１０４】
第４実施例のブロックの摩耗の様子は図７に、従来例のブロックの摩耗の様子は図６に示す通りであり、実線は摩耗前、想像線は摩耗後の接地端付近の断面を示している。
【０１０５】
従来例のブロックでは、図６に示すように接地端部が局所的に激しく摩耗していた。
【０１０６】
第４実施例のブロックでは、図７に示すように均等な摩耗状態となった。
【０１０７】
これより、ブロックの踏面を適正な形状とすることにより、局所的な偏摩耗が抑制されることが確認された。
【０１０８】
【発明の効果】
以上説明したように、本発明の空気入りタイヤは上記の構成としたので、接地圧の不均一を解消でき、操縦安定性能、耐偏摩耗性能を向上させることができる、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２−２線断面図及び、踏面の各部位における接地圧を示すグラフである。
【図３】 図１に示すブロックの３−３線断面図及び、踏面の各部位における接地圧を示すグラフである。
【図４】 周辺隆起部の寸法関係を示す断面図である。
【図５】 試験時の入力の方向を説明する説明図である。
【図６】 従来例のブロックの摩耗の様子を示すブロックの断面図である。
【図７】 第４実施形態のブロックの摩耗の様子を示すブロックの断面図である。
【図８】 従来例のブロックの断面図である。
【図９】 従来例のブロックの接地時の断面図及び、踏面の各部位における接地圧を示すグラフである。
。
【図１０】 バックリングを発生した従来例のブロックの断面図である。
【図１１】 （Ａ）は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り、（Ｂ）は図１１（Ａ）の１１（Ｂ）−１１（Ｂ）線断面図である。
【符号の説明】
１０ 空気入りタイヤ
１２ トレッド
１４ 周方向溝
１６ 横溝
１８ ブロック
２０ 周辺隆起部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire provided with a block in a tread, and particularly to a pneumatic tire excellent in steering stability performance and uneven wear resistance performance.
[0002]
[Prior art]
Conventionally, in a pneumatic tire, as shown in FIG. 8, the height of the block 100 is usually constant.
[0003]
When the block 100 having a constant height contacts the road surface 102 as shown in FIG. 9, the block 100 is deformed so as to swell in a barrel shape. Is pushed in the grounding direction.
[0004]
Further, since the rubber which is the main material of the tread is incompressible, the block 100 having a constant height has a large compression rigidity near the center (the compression rigidity is low because the vicinity of the block side portion can bulge outward). .)
[0005]
Therefore, when the block 100 having a constant height contacts the road surface, as shown in the graph of FIG. 9, the ground pressure becomes particularly large at the ground end and becomes large at the center of the block. The non-uniformity which becomes comparatively small arises between parts. For this reason, in the block 100 having a constant height, there is a problem that it is difficult for the entire tread to transmit the braking / driving force to the road surface.
[0006]
In addition, due to such grounding variation, as shown by the imaginary line in FIG. 6, it is likely that partial wear is likely to occur at an early stage, and during shear input due to local concentration of ground pressure ( As shown in FIG. 10, only the vicinity of the input side grounding end of the input F is grounded at a high pressure locally during braking and driving, and as a result, it turns up and adversely affects steering stability.
[0007]
On the other hand, in the conventional examination, the tread pattern has been improved in order to improve the ground contact characteristics. However, the current situation is that there is a limit in terms of the balance between drainage and other performances.
[0008]
As disclosed in Japanese Patent Application Laid-Open No. 62-279105, an invention has been made in which the central portion of the block is convex in the tire circumferential direction or the cross-section in the width direction. Usually, it is difficult to obtain a tread surface shape, and it is usually difficult to determine the shape with trial and error.
[0009]
The reason is the following two points. First, the distribution of the contact pressure depends on the shape of the pattern and is difficult to predict because it is affected by deformation at the time of input (for example, deformation from FIG. 8 to FIG. 9 or deformation from FIG. 8 to FIG. 10). Furthermore, the input received by the tire varies, and it is very difficult to uniquely determine an appropriate improvement direction that satisfies all of the inputs.
[0010]
[Problems to be solved by the invention]
In consideration of the above facts, the present invention defines a shape that optimizes the block height of the block present in the tread, thereby eliminating unevenness of the contact pressure and improving the steering stability performance and uneven wear resistance performance. It is an object to provide a tire entering.
[0011]
[Means for Solving the Problems]
The invention according to claim 1 is a pneumatic tire comprising a tread having a plurality of blocks partitioned by a circumferential groove extending substantially along the tire circumferential direction and a lateral groove intersecting the circumferential groove. In addition, a peripheral ridge that gradually decreases in height toward the block edge and the central portion of the block is formed on the tread surface of the block in the vicinity of the block edge, and the side surface of the block Dimension H1 from the intersection of the ridge and the peripheral ridge to the top of the peripheral ridge measured along the tire radial direction, and the peripheral ridge measured from the deepest part of the central region of the block along the tire radial direction The ratio H2 / H1 to the dimension H2 up to the top of is 1.5 or less .
[0012]
The operation of the pneumatic tire according to claim 1 will be described.
[0013]
The contact pressure when a conventional block with a constant height contacts the road surface is particularly large at the ground end and large at the center of the block, and relatively small between the ground end and the block central. 2 (see FIG. 9), as shown in FIG. 2, on the tread surface of the block 18, when the peripheral ridge 20 whose height gradually decreases toward the block edge and the center of the block is formed in the vicinity of the block edge, Since the block height on both sides of the peripheral bulge 20, that is, the block edge and the block center side is lower than the peripheral bulge 20, the ground pressure on the ground end and block central side can be lowered, Nonuniform pressure can be suppressed.
[0014]
The circumferential groove may be parallel to the tire circumferential direction or may be inclined to some extent with respect to the tire circumferential direction.
[0015]
Further, the lateral groove only needs to intersect at least the circumferential groove, may be parallel to the tire width direction, and may be inclined to some extent with respect to the tire width direction.
[0016]
Further, in order not to cause local wear that occurs due to uneven distribution of the contact pressure, it is preferable that the peripheral raised portion is raised smoothly, and when the block is sectioned in the height direction, the tread surface It is preferable that the contour line is composed of a smooth curve.
Here, when H2 / H1 is 1.5 or less, the ground pressure near the deepest part (near the center of the block) and the ground pressure at the top of the peripheral ridges are observed when the ground pressure distribution when the block is grounded is observed. And approach. Note that it is preferable that H2 / H1 is 1.0 or less because the contact pressure near the deepest part and the contact pressure at the top of the peripheral ridges are closer to each other.
If H2 / H1 exceeds 1.5, the ground pressure near the deepest part is separated from the ground pressure at the top of the peripheral ridges, making it impossible to make the ground pressure uniform.
[0017]
According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the peripheral ridges are formed at least at both block edges when the block is sectioned along the height direction. It is characterized by being.
[0018]
The operation of the pneumatic tire according to claim 2 will be described.
[0019]
In the pneumatic tire according to claim 2, when the blocks are cross-sectioned along the height direction, the peripheral ridges are formed at least at both block edges, so that at least the contact pressure in the vicinity of both block edges is obtained. And the contact pressure can be made constant along the cross-sectional direction.
[0020]
According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, the peripheral ridges are disposed in the vicinity of block edges on both sides in the tire circumferential direction of the block. It is said.
[0021]
The operation of the pneumatic tire according to claim 3 will be described.
[0022]
In the pneumatic tire according to claim 3, since the peripheral raised portions are arranged on both sides in the tire circumferential direction of the block, unevenness in the contact pressure in the tire circumferential direction of the block can be suppressed, and thereby, the braking / driving force can be reduced. As a result, it is possible to suppress the extreme local deformation caused by the steering and improve the steering stability, and to suppress the uneven wear near the tire circumferential direction end due to the uneven contact pressure in the tire circumferential direction.
[0023]
In addition, since the peripheral raised portions are arranged on both sides of the block in the tire circumferential direction, the tire does not have directionality.
[0024]
According to a fourth aspect of the present invention, in the pneumatic tire according to any one of the first to third aspects, the peripheral ridges are arranged in the vicinity of the block edge on both sides in the tire width direction of the block. It is characterized by having.
[0025]
The operation of the pneumatic tire according to claim 4 will be described.
[0026]
On the tread surface of the block, near the block edge in the tire width direction, from the top located closer to the center side of the block than the block edge in the tire width direction to the center portion of the block in the tire width direction and the block edge in the tire width direction When the peripheral bulging portion whose height gradually decreases is formed, the contact pressure at the contact end of the block in the tire width direction can be reduced, and uneven contact pressure in the tire width direction of the block can be suppressed.
[0027]
For this reason, generation | occurrence | production of the partial wear near the tire width direction edge part resulting from the nonuniformity of the contact pressure of a tire width direction can be suppressed.
[0028]
According to a fifth aspect of the present invention, in the pneumatic tire according to any one of the first to fourth aspects, measurement is performed along a tire radial direction from an intersection of the side surface of the block and the peripheral raised portion. The dimension H1 to the top of the peripheral ridge is 0.1 to 2.5 mm.
[0029]
The operation of the pneumatic tire according to claim 5 will be described.
[0030]
If this dimension H1 is a positive value, it is in a direction to alleviate the concentration of the contact pressure, so that the range in which the effect appears is wide.
[0031]
However, since the deformation of the block is limited under the input received by the tire, if this dimension H1 is too large, a portion that does not come into contact with the road surface on the tread surface of the block occurs. That is, the ground contact area is reduced.
[0032]
Therefore, the upper limit of the dimension H1 is set to 2.5 mm or less so as not to cause an extreme reduction in the contact area.
[0033]
On the other hand, when the dimension H1 is less than 0.1 mm, the effect of lowering the contact pressure at the block edge is low, and the effect of suppressing uneven contact pressure is insufficient.
[0034]
Therefore, the dimension H1 is set to 0.1 to 2.5 mm.
[0035]
The dimension H1 is more preferably 0.3 to 1.0 mm.
[0036]
The invention according to claim 6 is the pneumatic tire according to any one of claims 1 to 5, wherein the peripheral raised portion is measured along the tire radial direction from the deepest portion of the central region of the block. The dimension H2 to the top of is 0.1 to 2.0 mm.
[0037]
The operation of the pneumatic tire according to claim 6 will be described.
[0038]
By setting the dimension H2 from the deepest part of the central area of the block (the lower end of the hem of the peripheral ridge) to the top of the peripheral ridge measured along the tire radial direction to be 0.1 mm or more, the grounding of the central part of the block The pressure can be reliably reduced.
[0039]
The dimension H2 has an optimum value for each portion depending on the compression rigidity and shape of the block. The effect of the invention is greater than 0, that is, if this is also a positive value, the improvement is in the direction of improvement.
[0040]
However, if this value is too large, the ground contact area will be reduced (the center of the block will not be grounded), and the performance will deteriorate, so the effect will be significant and the range that does not impair the performance is 0.1 to 2.0 mm. It is.
[0041]
[0042]
[0043]
[0044]
[0045]
Invention according to claim 7, the pneumatic tire according to any one of claims 1 to 6, measured from the intersection of the side surface and the peripheral ridge of the block along the tread surface the The feature is that the dimension L1 to the top of the peripheral bulge is 1.0 to 10.0 mm.
[0046]
The operation of the pneumatic tire according to claim 7 will be described.
[0047]
By setting the dimension L1 to 1.0 to 10.0 mm, the ground pressure can be made more uniform, and if it is out of the range, the ground pressure may be non-uniform.
[0048]
In addition, it is preferable to set it as dimension L1 = 1.5-6.0 mm, and it is still more preferable to set it as dimension L1 = 1.5-4.0 mm.
[0049]
Here, when the dimension H1 is constant and the dimension L1 is different, the shorter the dimension L1, the sharper the shape, and the longer the dimension L1, the more gentle the shape.
[0050]
The invention according to claim 8 is the pneumatic tire according to any one of claims 1 to 7 , wherein the pneumatic tire is measured along the tread surface from the intersection of the side surface of the block and the peripheral raised portion. The ratio L1 / L2 between the dimension L1 to the top of the peripheral ridge and the dimension L2 from the top to the deepest part of the central region of the block measured along the tread surface is 1.0 or less. Yes.
[0051]
The operation of the pneumatic tire according to claim 8 will be described.
[0052]
Assuming that the block size is constant, the dimension L2 is a value determined depending on the dimension L1. In a general block such as a rectangle, the shape in which the central portion is gently recessed when the block is viewed in cross section is ideal from the compression rigidity distribution. To make the contact pressure distribution uniform, the dimension L2 is larger than the dimension L1. It is desirable to be larger.
[0053]
In the block pattern having a special shape, there may be partial inversion depending on the way of taking a cross section, but even in that case, a large effect can be expected with many arbitrary cross sections when L1 / L2 is 1.0 or less.
[0054]
The invention according to claim 9 is the pneumatic tire according to any one of claims 1 to 8 , wherein measurement is performed along a tire radial direction from an intersection of the side surface of the block and the peripheral raised portion. The ratio H1 / L1 between the dimension H1 to the top of the peripheral ridge and the dimension L1 from the intersection of the side surface of the block and the peripheral ridge to the top of the peripheral ridge measured along the tread surface is 1. It is characterized by being smaller than 0.0.
[0055]
The operation of the pneumatic tire according to claim 9 will be described.
[0056]
When the block is viewed in cross section, the effect of uniformizing the contact pressure distribution is enhanced by the dimension L1 being larger than the dimension H1.
[0057]
The reason is the deformation of the block, and a certain degree of gentleness is required for the curve of the tread when the block is viewed in cross section.
[0058]
The reason for this is that, if the curve is excessively steep, the end of the block floats off the road surface and the ground contact area is reduced, and uneven contact pressure is left in that part.
[0059]
Therefore, by making H1 / L1 smaller than 1.0, a uniform ground pressure can be obtained.
[0060]
The invention according to claim 10 is the peripheral bulge portion measured along the tire radial direction from the deepest portion of the central region of the block in the pneumatic tire according to any one of claims 1 to 9. The ratio H2 / L2 between the dimension H2 to the top of the block and the dimension L2 from the top to the deepest part of the central region of the block measured along the tread surface is smaller than 1.0.
[0061]
The operation of the pneumatic tire according to claim 10 will be described .
[0062]
When the block is viewed in cross section, the effect of making the ground pressure distribution uniform is enhanced by the dimension L2 being larger than the dimension H2.
[0063]
The reason is the deformation of the block, and a certain degree of gentleness is required for the curve of the tread when the block is viewed in cross section.
[0064]
The reason for this is that, if the curve is excessively steep, the end of the block floats off the road surface and the ground contact area is reduced, and uneven contact pressure is left in that part.
[0065]
Therefore, by making H2 / L2 smaller than 1.0, a uniform ground pressure can be obtained.
[0066]
According to an eleventh aspect of the present invention, in the pneumatic tire according to any one of the first to tenth aspects, a ratio T1 / T0 between the maximum height T0 of the block and the minimum height T1 of the block. Is characterized in that 0.7 ≦ T1 / T0 <1.0.
[0067]
The operation of the pneumatic tire according to claim 11 will be described .
[0068]
When T1 / T0 is less than 0.7, there is a possibility that the portion of the block having the minimum height T1, that is, the lower portion of the block will not touch the road surface and the ground contact area may be reduced. On the other hand, when T1 / T0 is 1, the effect of lowering the ground pressure is lost. Therefore, in order to ensure the ground contact area and to reliably obtain the effect of lowering the ground pressure, it is preferable to satisfy 0.7 ≦ T1 / T0 <1.0.
[0069]
A twelfth aspect of the present invention is the pneumatic tire according to any one of the first to eleventh aspects, wherein the peripheral ridge is formed along the entire circumference of the block edge. It is said.
[0070]
The operation of the pneumatic tire according to claim 12 will be described.
[0071]
Since the peripheral raised portion is formed along the entire circumference of the block edge, nonuniformity of the contact pressure can be suppressed over the entire circumference near the block edge regardless of the block shape.
[0072]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the pneumatic tire of the present invention will be described with reference to FIGS.
[0073]
As shown in FIG. 1, the tread 12 of the pneumatic tire 10 of the present embodiment includes a plurality of circumferential grooves 14 extending along the tire circumferential direction (arrow A direction) and the tire axial direction (arrow B direction). A plurality of blocks 18 are formed by a plurality of lateral grooves 16 extending along the.
[0074]
In addition, since the internal structure of this pneumatic tire 10 is not different from a general pneumatic tire, description of an internal structure is abbreviate | omitted.
[0075]
2 shows a cross section in the tire circumferential direction of the block 18, and FIG. 3 shows a cross section in the tire axial direction of the block 18.
[0076]
As shown in FIG. 2 and FIG. 3, peripheral ridges 20 are formed on the tread surface of the block 18 in the vicinity of each block edge on both sides in the tire circumferential direction and both sides in the tire width direction. Then, the peripheral bulging part 20 is continuously formed along the block outer periphery.
[0077]
As shown in the sectional view, it is preferable that the contour line of the peripheral raised portion 20 is constituted by a smooth curve.
[0078]
The peripheral ridge 20 is such that the top 20 </ b> A is located on the inner side of the block with respect to the extended line of the side surface (= groove wall) 18 </ b> A of the block 18 and has a height from the top 20 </ b> A toward the block edge and the center of the block 18. It is gradually decreasing.
[0079]
Below, the preferable range, such as a dimension of the peripheral protrusion part of the block 18, is demonstrated.
(1) As shown in FIG. 4, the dimension from the intersection C between the side surface 18A of the block 18 and the peripheral ridge 20 to the top 20A of the peripheral ridge 20 measured along the tire radial direction (arrow D direction) is H1. The dimension H1 is preferably 0.1 to 2.5 mm.
(2) When the dimension from the deepest part 18B of the central part of the block 18 to the top part 20A of the peripheral raised part 20 measured along the tire radial direction is H2, the dimension H2 is 0.1 to 2.0 mm. It is preferable.
(3) H2 / H1 is preferably 1.5 or less.
(4) When the dimension from the intersection C to the top 20A measured along the tread surface of the block 18 is L1, the dimension L1 is preferably 1.0 to 10.0 mm.
(5) When the dimension from the top portion 20A to the deepest portion 18B measured along the tread surface of the block 18 is L2, L1 / L2 is preferably 1.0 or less.
(6) It is preferable that H1 / L1 is smaller than 1.0.
(7) It is preferable that H2 / L2 is smaller than 1.0.
(8) It is preferable that the ratio T1 / T0 between the maximum height T0 of the block 18 and the minimum height T1 of the block 18 is 0.7 ≦ T1 / T0 <1.0 (see FIG. 4; minimum (The position of the height T1 may be the edge of the block or the center of the block.)
(Function)
Next, the effect | action of the pneumatic tire 10 of this embodiment is demonstrated.
[0080]
The contact pressure when a block with a constant height touches the road surface is particularly large at the ground end and large at the center of the block, and relatively small between the ground end and the block center. As shown in FIG. 2 and FIG. 3, when a peripheral ridge 20 having a height gradually decreasing toward the block edge and the block center of the tread surface of the block 18 is formed in the vicinity of the block edge, 2 and the imaginary line in FIG. 3) The contact pressure at the contact end and the block center can be lowered, and the contact pressure is made uniform in both the tire circumferential direction and the tire axial direction as shown in the graphs of FIGS. be able to.
[0081]
In this embodiment, the peripheral ridges 20 can be arranged on both sides of the block 18 in the tire circumferential direction to suppress uneven contact pressure in the tire circumferential direction, so that a buckling phenomenon caused by braking / driving force can be prevented. It is possible to improve the steering stability and to suppress uneven wear in the vicinity of the tire circumferential end due to uneven contact pressure in the tire circumferential direction.
[0082]
In addition, since the peripheral raised portions 20 are arranged on both sides in the tire width direction, it is possible to suppress the occurrence of uneven wear near the ends in the tire width direction due to uneven contact pressure in the tire width direction.
[0083]
In addition, by setting the dimension H1 to 0.1 to 2.5 mm, it is possible to suppress unevenness of the ground pressure without reducing the ground contact area near the block edge.
[0084]
By setting the dimension H2 to 0.1 to 2.0 mm, the contact pressure at the center of the block can be reliably reduced without reducing the contact area at the center of the block.
[0085]
By setting H2 / H1 to 1.5 or less, when the block 18 is grounded, the ground pressure in the vicinity of the deepest part (the center of the block) and the ground pressure at the top 20A of the peripheral ridge 20 are preferable.
[0086]
By setting the dimension L1 to 1.0 to 10.0 mm, the contact pressure can be made more uniform, which is preferable.
[0087]
By making L1 / L2 1.0 or less, it is preferable because the ground pressure distribution of the rectangular block 18 can be made uniform.
[0088]
By making H1 / L1 smaller than 1.0, it is preferable because a uniform ground pressure can be obtained.
[0089]
By making H2 / L2 smaller than 1.0, the effect of making the contact pressure distribution uniform is enhanced, which is preferable.
[0090]
Further, by setting the ratio T1 / T0 between the maximum height T0 of the block 18 and the minimum height T1 of the block 18 to 0.7 ≦ T1 / T0 <1.0, the ground contact area is secured and the ground pressure is lowered. This is preferable because the effect can be obtained with certainty.
[0091]
In the present embodiment, the circumferential groove 14 extends along the tire circumferential direction (arrow A direction) and the lateral groove 16 extends along the tire axial direction (arrow B direction). However, the present invention is not limited to this. The circumferential groove 14 may be inclined with respect to the tire circumferential direction, and the lateral groove 16 may be inclined with respect to the tire axial direction.
[0092]
Although the block 18 of the present embodiment is rectangular, the present invention is not limited to this, and the shape of the block 18 when the tread 12 is viewed in plan is the orientation of the circumferential groove 14 and the lateral groove 16, chamfering, and cutting. It may be a polygon such as a rhombus, hexagon, or octagon by adding a notch or the like, or may have a substantially U shape as shown in FIG. 11A, and may be a circle, an ellipse, or the like.
[0093]
In the block 18 shown in FIG. 11A, a peripheral ridge 20 (shaded portion in the figure) is formed along the block edge, and as shown in the cross-sectional view of FIG. Depending on the position of cutting, the peripheral ridges 20 appear in a total of three places on the cross-sectional view, that is, both block edges and the middle part thereof.
(Test example)
In order to confirm the effect of the present invention, eight types of tires of the example to which the present invention was applied and one type of conventional tire were prepared, and the steering stability performance and the ride comfort were evaluated by running the vehicle.
[0094]
The tire size was 195 / 50R15, and the vehicle was driven with an internal pressure of 2.0 kg / cm ² .
[0095]
The block dimensions are 30 mm in the tire circumferential direction, 20 mm in the tire width direction, and 9 mm in height.
[0096]
Evaluation is as shown in Table 1 below. In addition, evaluation is feeling evaluation by a test driver, and is an index display with a conventional tire as 100. Moreover, it shows that performance is so good that a numerical value is large.
[0097]
[Table 1]

It can be seen that the tires of the first to eighth embodiments to which the present invention is applied have improved steering stability performance compared to the conventional tires.
[0098]
Tables 2 and 3 below evaluated the contact pressure of the tire of the fourth example, which had the highest evaluation.
[0099]
[Table 2]

[0100]
[Table 3]

In addition, FIG. 5 shows the input conditions and their numbers considered at this time.
[0101]
Input 1 is a flat pushing load condition (corresponding to a surface pressure of 4 kgf / cm ² ), and inputs 2 to 8 are shear inputs in the direction shown in FIG. 5 (evaluated with a shear deformation of 1 mm).
[0102]
In Table 2, the degree of uniform contact pressure on the block tread is shown as an index for each input. The results improve the contact pressure non-uniformity by an average of 45% with the standard deviation of the contact pressure in the contact area.
[0103]
Further, Table 3 showing the area of the grounding area of this block for each input shows that the above improvement was made without impairing the grounding area, and it is suggested that it does not easily adversely affect other performances.
[0104]
FIG. 7 shows the state of wear of the block of the fourth embodiment, and FIG. 6 shows the state of wear of the block of the conventional example. The solid line shows a cross-section near the grounding end after wear, and the imaginary line shows the cross section near the grounding end after wear. ing.
[0105]
In the block of the conventional example, as shown in FIG.
[0106]
In the block of the fourth embodiment, uniform wear was obtained as shown in FIG.
[0107]
From this, it was confirmed that local uneven wear is suppressed by making the tread surface of the block into an appropriate shape.
[0108]
【The invention's effect】
As described above, since the pneumatic tire according to the present invention has the above-described configuration, it has an excellent effect of being able to eliminate uneven contact pressure and improving steering stability performance and uneven wear resistance performance. .
[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 a cross-sectional view taken along line 2-2 of the block shown in FIG. 1 and a graph showing the contact pressure at each part of the tread.
3 is a cross-sectional view taken along line 3-3 of the block shown in FIG. 1 and a graph showing the contact pressure at each part of the tread surface.
FIG. 4 is a cross-sectional view showing a dimensional relationship between peripheral ridges.
FIG. 5 is an explanatory diagram illustrating an input direction during a test.
FIG. 6 is a cross-sectional view of a block showing how the block of the conventional example is worn.
FIG. 7 is a cross-sectional view of a block showing a state of wear of the block of the fourth embodiment.
FIG. 8 is a cross-sectional view of a conventional block.
FIG. 9 is a cross-sectional view of a conventional block at the time of ground contact and a graph showing the contact pressure at each part of the tread surface.
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FIG. 10 is a cross-sectional view of a conventional block in which buckling occurs.
11A is a plan view of a block of a pneumatic tire according to another embodiment, and FIG. 11B is a cross-sectional view taken along line 11 (B) -11 (B) of FIG. 11A.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Tread 14 Circumferential groove 16 Lateral groove 18 Block 20 Peripheral bulge

Claims (12)

A pneumatic tire comprising a plurality of blocks in a tread partitioned by a circumferential groove extending substantially along the tire circumferential direction and a transverse groove intersecting the circumferential groove,
On the tread surface of the block, in the vicinity of the block edge, there is formed a peripheral ridge that gradually decreases in height toward the block edge and the center of the block ,
Measured along the tire radial direction from the deepest part of the central region of the block to the dimension H1 from the intersection of the side surface of the block and the peripheral raised portion to the top of the peripheral raised portion measured along the tire radial direction. The pneumatic tire according to claim 1, wherein a ratio H2 / H1 to a dimension H2 to the top of the peripheral raised portion is 1.5 or less .   2. The pneumatic tire according to claim 1, wherein the peripheral bulging portion is formed at least at both end edges of the block when the block is sectioned along the height direction. 3.   3. The pneumatic tire according to claim 1, wherein the peripheral bulge portion is disposed in the vicinity of a block edge on both sides in a tire circumferential direction of the block.   The pneumatic tire according to any one of claims 1 to 3, wherein the peripheral ridges are arranged in the vicinity of block edges on both sides in the tire width direction of the block.   The dimension H1 from the intersection of the side surface of the block and the peripheral ridge to the top of the peripheral ridge measured along the tire radial direction is 0.1 to 2.5 mm. The pneumatic tire according to claim 4.   The dimension H2 from the deepest part of the central region of the block to the top of the peripheral ridge measured along the tire radial direction is 0.1 to 2.0 mm. A pneumatic tire given in any 1 paragraph. Claims 1 to dimension L1 from the intersection between the side surface and the peripheral ridge of the block to the top of the peripheral ridges measured along the tread surface characterized in that it is a 1.0~10.0mm The pneumatic tire according to any one of items 6 . The dimension L1 from the intersection of the side surface of the block and the peripheral ridge to the top of the peripheral ridge measured along the tread surface, and the deepest portion of the central region of the block measured from the top along the tread surface The pneumatic tire according to any one of claims 1 to 7, wherein a ratio L1 / L2 with respect to the dimension L2 is 1.0 or less. Dimension H1 from the intersection of the side surface of the block and the peripheral ridge to the top of the peripheral ridge measured along the tire radial direction, and along the tread surface from the intersection of the side of the block and the peripheral ridge The pneumatic tire according to any one of claims 1 to 8, wherein a ratio H1 / L1 to a dimension L1 to the top of the peripheral bulge portion measured in step 1 is smaller than 1.0. . The dimension H2 from the deepest part of the central region of the block to the top of the peripheral ridge measured along the tire radial direction, and the dimension from the top to the deepest part of the central region of the block measured along the tread surface. The pneumatic tire according to any one of claims 1 to 9, wherein a ratio H2 / L2 to L2 is smaller than 1.0. The ratio T1 / T0 of the minimum height T1 of the block with maximum height T0 of the block, one of claims 1 to 10, characterized in that a 0.7 ≦ T1 / T0 <1.0 the pneumatic tire according to any one of claims. The pneumatic tire according to any one of claims 1 to 11, wherein the peripheral protruding portion is formed along the entire circumference of the block edge.

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