JP3917420B2 - Pneumatic tire - Google Patents

Description

試験の結果、実施例１〜実施例４のタイヤは、従来例及び比較例のタイヤに対して乾燥路面での操縦安定性能、及び氷上性能が向上しているのが分かる。
【００６２】
【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、従来よりも乾燥路面での操縦安定性能、及び氷上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に示すブロックの斜視図である。
【図３】ブロックのタイヤ幅方向断面図である。
【図４】ブロックのタイヤ周方向断面図である。
【図５】ブロックのタイヤ幅方向断面における接地圧分布を示す説明図である。
【図６】ブロックのタイヤ周方向断面における接地圧分布を示す説明図である。
【図７】従来例のブロックの断面図である。
【図８】従来のブロックにおける乾燥路面での接地圧分布を示す説明図である。
【図９】従来のブロックにおける氷路面での接地圧分布を示す説明図である。
【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 隆起部
２２ 陥没部
２４ 陥没部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire provided with a block in a tread, and more particularly to a pneumatic tire excellent in steering stability performance and on-ice performance.
[0002]
[Prior art]
Conventionally, in a pneumatic tire, as shown in FIG. 7, the height of the block 100 is usually constant.
[0003]
As shown in FIG. 8, when the block 100 having a constant height contacts the dry road surface 102, a frictional force is generated between the block 100 and the dry road surface 102. In order to be deformed to swell into a barrel shape, bending acts on the grounding end of the block 100, and the grounding end 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]
Accordingly, when the block 100 having a constant height contacts the dry road surface 102, the contact pressure becomes particularly large at the contact end (block end) and large at the center of the block as shown in the graph of FIG. Thus, a non-uniformity that is relatively small occurs between the ground contact end and the block center.
[0006]
For this reason, in the block 100 having a constant height, the tread surface is particularly important in steering stability in a small rudder angle region (when the slip angle is small) or a large rudder angle region (when the slip angle is large). There was a problem that it was difficult for the whole to convey lateral force to the road surface.
[0007]
Further, when the block 100 having such a constant height comes into contact with the ice road surface 104 as shown in FIG. 9, there is almost no frictional force between the block 100 and the ice road surface 104. Is deformed into a trapezoidal shape in which the tread surface is widened, and the bending contact as in the case of the dry road surface 102 does not work at the ground contact end of the block 100.
[0008]
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). .)
[0009]
Therefore, when the block 100 having a constant height contacts the ice road surface 104, the contact pressure becomes particularly large at the center of the block as shown in the graph of FIG.
[0010]
If the contact pressure is uneven, the contact area is smaller than that when the contact pressure is uniform. Therefore, in the block 100 having a constant height, the tread is particularly important during driving and braking, which is important for performance on ice. As a whole, there is a problem that it is difficult to transmit driving force and braking force to the road surface.
[0011]
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.
[0012]
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.
[0013]
Further, as disclosed in Japanese Patent Application Laid-Open No. 2000-71719, the invention is intended to make the contact pressure uniform by forming a peripheral bulging portion whose height gradually decreases toward the block edge and the central portion of the block in the vicinity of the block edge. However, this method alone has improved the performance of a dry road surface, but it has been difficult to achieve compatibility with the performance of an ice road surface.
[0014]
[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 stability of driving and the performance on ice. The object is to provide a tire.
[0015]
[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, when viewed in a cross section along the tire width direction orthogonal to the tire equatorial plane, the height of the tread of the block gradually increases from the end toward the center, and then toward the center. height gradually decreases, when viewed in cross section along a tire circumferential direction parallel to the tire equatorial plane, so that the height toward the end to the central portion is gradually reduced, ridges and depressions have been eclipsed set It is characterized by that.
[0016]
Next, the operation of the pneumatic tire according to claim 1 will be described.
[0017]
The distribution of contact pressure in the block width direction when a conventional block with a constant height contacts the dry road surface is particularly large at the contact end and large at the center of the block, and between the contact end and the block center. However, when viewed in a cross-section along the tire width direction, the height once increases gradually from the end toward the center, and then increases toward the center. Since the block height gradually decreases, the block height on the block edge and the center side of the block becomes lower, so that the ground contact on the ground end side in the tire width direction and the ground side on the center side in the tire width direction compared to the block with a constant tread height The pressure can be lowered, and the contact pressure can be made uniform in the tire width direction (see FIG. 5).
[0018]
In the steering stability performance, it is important that the entire tread surface of the block transmits a lateral force to the road surface in a small rudder angle region and a large rudder angle region. However, in the pneumatic tire according to claim 1, Since the non-uniformity of the contact pressure in the tire width direction of the block is suppressed, the contact property of the block at the time of lateral force input on the dry road surface is good, and thus high steering stability performance is obtained on the dry road surface.
[0019]
Next, when a conventional block with a constant height contacts the ice road surface, the distribution of the contact pressure in the circumferential direction of the block is large at the center of the block and relatively small at the contact end (see FIG. 9). The block whose height gradually decreases from the end toward the center when viewed in a cross section along the tire circumferential direction lowers the contact pressure on the center of the block in the tire circumferential direction on the icy road surface. The contact pressure on the icy road surface can be made uniform in the tire circumferential direction (see FIG. 6).
[0020]
In the performance on ice, it is important that the entire tread transmits the driving force and the braking force to the icy road surface at the time of driving and braking. Since unevenness of the ground contact pressure in the direction is suppressed, the ground contact property of the block during driving and braking on the ice road is good, and therefore high performance on ice can be obtained.
[0021]
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.
[0022]
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.
[0023]
Further, in order not to cause local wear that occurs due to uneven distribution of the contact pressure, the height of the tread is preferably smoothly changed, and when the block is sectioned in the height direction, It is preferable that the tread surface outline is constituted by a smooth curve.
[0024]
The invention according to claim 2 is the pneumatic tire according to claim 1,
In any section in the tire width direction perpendicular to the tire equatorial plane in the tire circumferential direction, the height once increases gradually from the end toward the center, and then gradually decreases toward the center, and the tire width also in the tire circumferential direction cross section parallel to the tire equatorial plane of which parts of the direction, so that the height toward the central portion is gradually reduced from the end portion, ridges and depressions are kicked set, as characterized by Yes.
[0025]
Next, the operation of the pneumatic tire according to claim 2 will be described.
[0026]
In the tire width direction cross section orthogonal to the tire equatorial plane of any part in the tire circumferential direction, the height of the tread gradually increases from the end toward the center and then gradually decreases toward the center. By doing so, the contact pressure can be made uniform in the tire width direction in the entire block. Thereby, steering stability performance can be improved.
[0027]
In addition, in any section in the tire circumferential direction parallel to the tire equatorial plane in the tire width direction, the contact pressure is reduced throughout the entire block by adopting a tread shape that gradually decreases in height from the end toward the center. Uniform in the direction. Thereby, performance on ice can be improved.
[0028]
According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect , the highest portion and the lowest portion of the tread surface in a cross section in the tire width direction perpendicular to the tire equatorial plane of the block. The height difference and the height difference between the highest part and the lowest part of the tread on the tire circumferential cross section parallel to the tire equatorial plane are each in the range of 0.1 to 2.5 mm.
[0029]
Next, the operation of the pneumatic tire according to claim 3 will be described.
[0030]
Under the input received by the tire, there is a limit to the deformation of the block. Therefore, if the height difference is too large, a part of the block tread that does not come into contact with the road surface occurs. That is, the ground contact area may be reduced.
[0031]
Therefore, the upper limit of the height difference dimension is set to 2.5 mm so as not to cause an extreme reduction in the contact area.
[0032]
On the other hand, when the height difference is less than 0.1 mm, the effect of lowering the contact pressure at the block edge and the block center is low, and the effect of suppressing uneven contact pressure is insufficient.
[0033]
Therefore, it is preferable that the height difference is in the range of 0.1 to 2.5 mm.
[0034]
It is more preferable that the height difference is in the range of 0.3 to 1.0 mm.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the pneumatic tire of the present invention will be described with reference to FIGS. 1 to 6.
[0036]
As shown in FIG. 2, the tread 12 of the pneumatic tire 10 of the present embodiment includes a plurality of circumferential grooves 14 extending in the tire circumferential direction (arrow A direction) and the tire width direction (arrow B direction). A plurality of blocks 18 are formed by a plurality of lateral grooves 16 extending along the.
[0037]
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.
[0038]
1 shows a block 18 in a perspective view, FIG. 3 shows a cross section in the tire width direction of the block 18, and FIG. 4 shows a cross section in the tire circumferential direction of the block 18.
[0039]
As shown in FIGS. 1, 3, and 4, raised portions 20 are formed on the tread surface of the block 18 in the vicinity of the block edges on both sides in the tire width direction.
[0040]
The raised portion 20 is continuously formed in the tire circumferential direction, and the height thereof is set to be highest at both ends in the tire circumferential direction and lowest in the tire circumferential central portion, and the block height. As shown in FIG. 4, the distance gradually decreases gradually from both ends in the tire circumferential direction toward the center in the tire circumferential direction.
[0041]
Further, a depressed portion 22 continuous in the tire circumferential direction is provided between the raised portion 20 and the raised portion 20, and a depressed portion 24 continuous in the tire circumferential direction is provided on the block end side of the raised portion 20 in the tire width direction. Yes.
[0042]
The depressed portion 22 and the depressed portion 22 are set to have the highest end portions in the tire circumferential direction and the lowest central portion in the tire circumferential direction, and the block height is from the both ends in the tire circumferential direction toward the central portion in the tire circumferential direction. It gradually decreases smoothly.
[0043]
Further, the depressed portion 22, the depressed portion 22 and the raised portion 20 are smoothly connected to each other.
[0044]
In the block 18 of the present embodiment, the height of the contour shape of the tread when viewed in a cross section along the tire width direction is once increased gradually from the end to the center as shown in FIG. The shape gradually decreases toward the center, and the contour shape of the tread when viewed in a cross section along the tire circumferential direction is gradually decreased from the end toward the center as shown in FIG. Shape.
[0045]
As shown in FIG. 3, the height difference D1 between the highest part and the lowest part of the tread when the block 18 is viewed in a cross section along the tire width direction is preferably within a range of 0.1 to 2.5 mm. More preferably within the range of 0.3 to 1.0 mm.
[0046]
Further, as shown in FIG. 4, the height difference D2 between the highest part and the lowest part of the tread when the block 18 is viewed in a cross section along the tire circumferential direction is within a range of 0.1 to 2.5 mm. Is preferable, and the range of 0.3 to 1.0 mm is more preferable.
(Function)
Next, the effect | action of the pneumatic tire 10 of this embodiment is demonstrated.
[0047]
The distribution of contact pressure in the block width direction when a block with a constant height contacts the dry road surface is particularly large at the contact end and large at the center of the block, and relative between the contact end and the block center. As shown in FIG. 3, when the block 18 is viewed in a cross section along the tire width direction, the height once increases gradually from the end toward the center, and then toward the center. The shape in which the height gradually decreases toward the surface can reduce the contact pressure on the contact end side in the tire width direction and the center side in the tire width direction in comparison with the block having a constant tread height, as shown in FIG. Thus, the contact pressure can be made uniform in the tire width direction throughout the block 18.
[0048]
Thereby, the grounding property of the block at the time of lateral force input on the dry road surface is improved, and high steering stability performance on the dry road surface is obtained.
[0049]
Further, in the block 18 of the present embodiment, the unevenness of the contact pressure in the tire width direction can be suppressed as described above, so that the buckling due to the lateral force is reduced on the road surface where the frictional force acts like the dry road surface. Stable generation performance can be improved by suppressing occurrence.
[0050]
In addition, when a block with a constant height contacts the icy road surface, the distribution of the contact pressure in the block circumferential direction is large at the center of the block and relatively small at the contact end, but as shown in FIG. When the block 18 is viewed in a cross-section along the tire circumferential direction, the height gradually decreases from the end toward the central portion, so that the center portion in the tire circumferential direction is compared with the block having a constant tread height. The contact pressure on the side can be reduced, and as shown in FIG. 6, the contact pressure can be made uniform in the tire circumferential direction in the entire block 18.
[0051]
Thereby, the grounding property of the block at the time of driving and braking on an ice road surface is improved, and high on-ice performance is obtained.
[0052]
Further, in the tire circumferential direction cross section and the tire width direction cross section, the height difference of the tread surface of the block 18 is set within the range of 0.1 to 2.5 mm, so that the tire width is reduced without reducing the contact area of the block 18. The contact pressure can be made uniform in both the direction and the tire circumferential direction.
[0053]
In this embodiment, the circumferential groove 14 extends along the tire circumferential direction (arrow A direction), and the lateral groove 16 extends along the tire width 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 width direction.
[0054]
Further, the block 18 of the present embodiment is rectangular, but 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. By adding a notch or the like, it may be a polygon such as a rhombus, hexagon, or octagon, may have a substantially U shape, may be a circle, an ellipse, or the like.
(Test example)
In order to confirm the effect of the present invention, four types of tires of the example to which the present invention was applied, two types of tires of comparative examples, and one type of conventional tire were prepared, and evaluation of steering stability performance and on-ice performance was performed by running an actual vehicle. Went.
[0055]
The tire size was 195 / 50R15 and the vehicle was driven with an internal pressure of 200 kPa.
[0056]
The block dimensions are 30 mm in the tire circumferential direction, 20 mm in the tire width direction, and 9 mm in height (average value).
[0057]
The conventional tire is a tire having blocks having a constant height.
[0058]
The tire of an Example and a comparative example is a tire which has a protruding part and a depression part in a tread surface like embodiment mentioned above.
[0059]
As shown in FIG. 3, the distance L1 from the block end to the top of the raised portion 20 is 3 mm.
[0060]
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.
[0061]
[Table 1]

As a result of the test, it can be seen that the tires of Examples 1 to 4 have improved driving stability performance on the dry road surface and performance on ice as compared with the tires of the conventional example and the comparative example.
[0062]
【The invention's effect】
As described above, since the pneumatic tire of the present invention has the above-described configuration, it is possible to eliminate unevenness of the contact pressure, and it is possible to improve the steering stability performance on the dry road surface and the performance on ice more than before. It has an excellent effect.
[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 perspective view of the block shown in FIG.
FIG. 3 is a sectional view of a block in the tire width direction.
FIG. 4 is a sectional view in the tire circumferential direction of a block.
FIG. 5 is an explanatory diagram showing a contact pressure distribution in a cross section in the tire width direction of the block.
FIG. 6 is an explanatory diagram showing a contact pressure distribution in a tire circumferential cross section of a block.
FIG. 7 is a cross-sectional view of a conventional block.
FIG. 8 is an explanatory diagram showing a contact pressure distribution on a dry road surface in a conventional block.
FIG. 9 is an explanatory diagram showing a contact pressure distribution on an icy road surface in a conventional block.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Tread 14 Circumferential groove 16 Horizontal groove 18 Block 20 Raised part 22 Depressed part 24 Depressed part

Claims (3)

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,
When viewed in a cross section along the tire width direction orthogonal to the tire equator plane, the height of the tread surface of the block gradually increases from the end toward the center and then increases toward the center. decreasing and, when viewed in cross section along a tire circumferential direction parallel to the tire equatorial plane, a height direction from the end to the central portion so as to gradually decrease, ridges and depressions are kicked set, it Pneumatic tire characterized by. In any section in the tire width direction perpendicular to the tire equatorial plane in the tire circumferential direction, the height once increases gradually from the end toward the center, and then gradually decreases toward the center, and the tire width also in the tire circumferential direction cross section parallel to the tire equatorial plane of which part of the direction, and characterized such that the height toward the central portion is gradually reduced from the end portion, ridges and depressions are kicked set, that The pneumatic tire according to claim 1. The height difference between the highest and lowest portions of the tread surface in the tire width direction cross section orthogonal to the tire equator surface of the block, and the highest and lowest portions of the tread surface in the tire circumferential section parallel to the tire equator surface 3. The pneumatic tire according to claim 1, wherein a difference in height from the portion is within a range of 0.1 to 2.5 mm.

Images