JP3954174B2 - Pneumatic tire - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire having a sipe in a block land portion provided on a surface portion of a tread.
[0002]
[Prior art]
Conventionally, when the tread part is configured with a block pattern divided by a plurality of main grooves extending in the circumferential direction and a plurality of lug grooves extending in a direction intersecting the main grooves on the surface portion of the tread in a pneumatic tire, the performance on ice In order to improve this, a horizontal sipe is formed in the block-shaped land portion. The on-ice performance is improved by increasing the edge component due to the horizontal sipe.
[0003]
[Problems to be solved by the invention]
However, when a double-sided opening type horizontal sipe that crosses the block-shaped land portion is provided in the block width direction, the rigidity of the block-shaped land portion divided into two by the horizontal sipe decreases. Therefore, there is a problem that the possibility of heel-and-toe wear increases due to the block-like land portion falling down due to friction with the road surface during tire rotation contact. In order to prevent the block-like land portion from falling down, it is also conceivable to form a wave-shaped sipe in the depth direction of the block-like land portion. That is, when the tire having the sipe formed in contact with the ground is rotated, the unevenness of the block-like land portions facing each other with the sipe interposed therebetween meshes to prevent the tire from falling down. However, when the sipe is formed in such a wavy shape, there is a problem that if the sipe is formed in an effective shape with respect to one rotation direction, the sipe does not always work effectively in the other rotation direction.
[0004]
In consideration of such facts, the present invention can prevent heel-and-toe wear of the block-shaped land portion at the time of tire rotation contact regardless of the rotation direction of the tire when a horizontal sipe is provided in the block-shaped land portion. It is an object to provide a pneumatic tire.
[0005]
[Means for Solving the Problems]
In the first aspect of the present invention, a block-shaped land portion divided into a plurality of sections by a main groove formed along the circumferential direction of the cylindrical tread and a lug groove formed in a direction intersecting the main groove is provided. A pneumatic tire comprising at least one sipe extending substantially in the tire width direction in the block-like land portion, wherein the sipe is linear on the tread surface side in the depth direction of the block-like land portion. And a first convex portion projecting in the first circumferential direction inside the block-shaped land portion when the circumferential direction of the tread is defined as the first circumferential direction and the second circumferential direction, respectively, by the rotational direction. And a wavy portion having at least a second convex portion convex in the second circumferential direction, the first convex portion on the tread surface side in the depth direction of the block-shaped land portion, and the second convex portion on the sipe bottom portion side A first wavy portion comprising: The second convex portions on the red surface side, and a second corrugated portion comprising a first convex portion in the sipe bottom side at different positions in the sipe longitudinal direction, said straight portion and said corrugated portion in the tire width of said block-shaped land portion The sipe wall surface is formed as a surface that is open on both side surfaces in the direction and smoothly continues between the both side surfaces .
[0006]
Therefore, since the sipe formed in the block-shaped land portion has a wave-shaped portion in the depth direction, the wave-shaped portions of the block-shaped land portion constituting the sipe mesh with each other at the time of tire rotation contact, Increase the rigidity of the block-shaped land to prevent falling down and prevent heel and toe wear. Further, the wave-shaped portion of the sipe is provided with a first convex portion convex in the first circumferential direction in the depth direction of the block on the tread surface side and a second convex portion convex in the second circumferential direction on the sipe bottom side. A block constituting a sipe since the second wavy portion provided with the second convex portion on the tread surface side and the first convex portion on the sipe bottom side opposite to the first wavy portion is provided at a different position in the longitudinal direction of the sipe. The meshing state of the wavy portions of the land portions is opposite in the circumferential direction of the tread between the first wavy portion and the second wavy portion. Therefore, the same effect can be obtained even if the rotation direction of the tire is reversed. That is, the pneumatic tire of the present invention has no directionality.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
[ Comparative example ]
Hereinafter, with reference to FIGS. 1 to 5 and Comparative Examples will be described before describing the first embodiment of the present invention.
[0008]
As shown in FIG. 1, the pneumatic tire 10 includes a cylindrical tread 12 straddling a pair of left and right sidewalls (not shown). The tread 12 includes a plurality of main grooves 14 formed along the tire circumferential direction (hereinafter referred to as p direction), and a plurality of lug grooves 16 formed along the tire width direction (hereinafter referred to as w direction). Is formed. A plurality of blocks 18 are defined by the main groove 14 and the lug groove 16. These blocks 18 are formed with horizontal sipes 20 extending along the w direction.
[0009]
FIG. 2 shows a perspective view of a single block. As shown in this figure, the lateral sipe 20 is a double-sided sipe having both ends opened to the block end faces 18a and 18b. In the width direction of the block 18 (same as the tire width direction, hereinafter referred to as the “w direction”), the horizontal sipe 20 extends horizontally from the half of the block 18 to the block end surface 18a side and from the half to the block end surface 18b side. It is divided into sipe 20b.
[0010]
The horizontal sipe 20a includes a straight portion 22a on the surface portion of the block 18 and a wave-like portion 24 on the bottom side of the sipe in the depth direction of the block 18 (hereinafter referred to as d direction). In the wavy portion 24, as shown in FIG. 2, a first convex portion 24a convex in the first direction (hereinafter referred to as the p1 direction) in the circumferential direction of the tread (same as the tire circumferential direction; hereinafter referred to as the p direction) is blocked. A second convex portion 24 b that is convex in the second direction (hereinafter referred to as the p2 direction) is formed on the bottom side of the horizontal sipe 20 on the surface side of 18.
[0011]
Similarly, the horizontal sipe 20b is provided with a straight portion 22b on the surface portion and a corrugated portion 26 inside in the d direction. The straight portion 22b is formed continuously with the straight portion 22a, and constitutes the straight portion 22 integrally. On the other hand, in the wavy portion 26, a second convex portion 26a convex in the p2 direction is formed on the surface side of the block 18, and a first convex portion 26b convex in the p1 direction is formed on the bottom side of the horizontal sipe 20. As a result, as shown in FIG. 3, the wavy portions 24 and 26 of the horizontal sipes 20a and 20b are symmetrical with each other across the plane including the straight portions 22a and 22b.
[0012]
For example, the above-described configuration can be obtained by forming the wavy portions 24 and 26 of the horizontal sipe 20 configured as described above with sine curves and shifting the phase by 180 degrees.
[0013]
In addition, let the p1 side of the block 18 divided | segmented by the horizontal sipe 20 in the p direction be the front-end | tip part 18c, and let the p2 side be the front-end | tip part 18d. As shown in FIG. 3, the sipe wall surface 30 of the distal end portion 18 c includes a concave portion 30 a and a convex portion 30 b corresponding to the wavy portion 24 on the horizontal sipe 20 a side, and a convex portion 30 c and a convex portion 30 c corresponding to the wavy portion 26 on the horizontal sipe 20 b side. A recess 30d is formed.
[0014]
Similarly, the sipe wall surface 32 of the tip 18d forms a convex portion 32a and a concave portion 32b on the side of the horizontal sipe 20a, and a concave portion 32c and a convex portion 32d on the side of the horizontal sipe 20b.
[0015]
When the pneumatic tire 10 having the tread 12 formed with the block 18 configured as described above is actually mounted on an automobile, the following effects are obtained.
[0016]
That is, as shown in FIG. 4, the pneumatic tire 10 rotates in the P1 direction as the automobile travels, and the block 18 formed on the surface of the tread 12 contacts the ground. The deformation state of the block 18 in this case will be described on the end face 18a side.
[0017]
When the block 18 rotates and comes into contact with the ground, first, the edge portions of the tip portions 18c and 18d come into contact with the ground, and the tip portions 18c and 18d are elastically deformed by a frictional force. At this time, the tip 18c receives a stronger compressive stress and is displaced in the direction of the arrow A1 relative to the tip 18d. At this time, the distal end portion 18d is displaced in the arrow A2 direction relative to the distal end portion 18c. As a result, the block surface side of the concave portion 30a constituting the sipe wall surface 30 of the tip end portion 18c and the block surface side of the convex portion 32a constituting the sipe wall surface 32 of the block 18d abut. Since the distance H1 from the surface where the tip 18c and the tip 18d abut to the block surface is shorter than the distance H2 from the sipe bottom to the block surface, the bending moment acting on the tips 18c and 18d is sufficiently small. . That is, the tip portions 18c and 18d have substantially sufficient rigidity, and the collapse is suppressed.
[0018]
Therefore, uneven wear of the block 18 can be prevented. Further, since the tip portions 18c and 18d are prevented from falling down in comparison with the block in which the linear sipe is formed in the sipe depth direction, the ground contact property on the block surface is improved and the steering stability is also improved.
[0019]
On the other hand, as shown in FIG. 5, when the rotation direction of the pneumatic tire 10 is reversed (p2 direction), the tip portions 18d and 18c are elastically deformed by friction. At this time, the tip portion 18d receives a stronger compressive stress and is displaced in the direction of the arrow B1 relative to the tip portion 18c. Conversely, the tip 18c is displaced in the B2 direction relative to the tip 18d. In this case, the contact portion between the tip portions 18 d and 18 c is on the block surface side of the concave portion 32 b constituting the sipe wall surface 32 and on the block surface side of the convex portion 30 b constituting the sipe wall surface 30. Since the difference between the distance H3 from the contact point between the tip portions 18d and 18c to the block surface and the distance H2 is not so large, the bending moment acting on the tip portions 18c and 18d is not sufficiently reduced, and it is difficult to suppress collapse. .
[0020]
That is, sufficient rigidity cannot be given to the front end portions 18c and 18d of the block 18, and the collapse may continue and heel and toe wear may occur.
[0021]
At this time, on the side where the opposite side sipe 20b is formed, the shape of the wavy portion 26 is such that the irregularities of the wavy portion 24 of the side sipe 20a are reversed in the p direction. Therefore, the same operation as the horizontal sipe 20a shown in FIG. 4 occurs in the horizontal sipe 20b. That is, the displacement of the tip portions 18c and 18d is prevented on the side of the horizontal sipe 20b. As a result, the tip portions 18c and 18d of the block 18 acquire sufficient rigidity, and the collapse is suppressed.
[0022]
As described above, according to the comparative example , since the wavy portions 24 and 26 are provided in the horizontal sipe 20 formed in the block 18, the tip end portions 18 c and 18 d abut at the positions of the wavy portions 24 and 26 during the ground rotation. Thereby, the bending moment which acts on the front-end | tip parts 18c and 18d becomes small, the rigidity of the block 18 is improved substantially, and collapse is suppressed. Therefore, heel and toe wear can also be prevented. Moreover, since the horizontal sipe 20 is divided into the horizontal sipe 20a and the horizontal sipe 20b, and the irregularities of the respective wavy portions are reversed in the p direction, the same fall-in suppressing effect can be obtained no matter which direction the tire is mounted. That is, since this tire has no directionality, heel-and-toe wear can be prevented regardless of the rotational direction.
[ First Embodiment ]
Next, the first embodiment will be described.
[0023]
Similar to the comparative example , a horizontal sipe 34 is formed in the block 18. The horizontal sipe 34 is formed with a straight portion 36 and a wave-like portion 38 from the block surface side in the d direction. The shape of the wavy portion 38 is the same as that of the comparative example on the block end faces 18a and 18b (see FIG. 3). However, as shown in FIG. 6, the sipe wall surface is formed of a smoothly continuous surface between the block end surfaces 18 a and 18 b so that the straight portion 36 and the waved portion 38 of the horizontal sipe 34 are open on both sides. .
[0024]
Accordingly, the first convex portion 38a on the block end surface 18a of the wavy portion 38 has a convex portion in the p1 direction that decreases to half the width of the block 18 in the w direction, becomes a straight line at a half position, and from the half position. The convex portion in the p2 direction increases toward the block end surface 18b, and becomes the second convex portion 38b on the block end surface 18b.
[0025]
Even in this case, in the w-shaped portion 38, the concave and convex shapes in the p direction from the half to the block end face 18a side and from the half to the block end face 18b side are reversed.
[0026]
Therefore, as in the comparative example , it is possible to suppress the collapse and prevent the heel and toe wear regardless of the rotation of the tire. In addition, in this embodiment, since the horizontal sipe 34 is a double-sided opening type even in the wavy portion 38, the drainage performance is improved and the wet performance is improved.
[0027]
The shape of the sipe is not limited to the above example, and the same effect can be obtained with the following.
[0028]
For example, as shown in FIG. 7, the first convex portion 42a and the second convex portion 42b of the wavy portion 42 of the horizontal sipe 40 are formed in a trapezoidal shape, and as shown in FIG. The first convex portion 46a and the second convex portion 46b are formed in a triangular shape. As shown in FIG. 9, the first convex portion 50a and the second convex portion 50b of the wavy portion 50 of the horizontal sipe 48 are formed in a semicircle. Things can be considered.
[0029]
In the comparative example , the horizontal sipe 20 is composed of the two horizontal sipes 20a and 20b. However, the horizontal sipe 20a and the horizontal sipe 20b may be alternately arranged a plurality of times in the w direction .
[0030]
[0031]
[0032]
[0033]
[0034]
【The invention's effect】
Since the pneumatic tire of the present invention has the above-described configuration, the block land portion can be prevented from falling down and the occurrence of heel and toe wear can be suppressed regardless of the rotation direction of the tire.
[Brief description of the drawings]
FIG. 1 is a plan view of a tread of a pneumatic tire according to a comparative example .
2 is a perspective view of a block according to a comparative example.
FIG. 3 is a side view of a block according to a comparative example .
FIG. 4 is a side view for explaining displacement of a block according to a comparative example .
FIG. 5 is a side view for explaining displacement of a block according to a comparative example .
FIG. 6 is a perspective view of a block according to the first embodiment .
FIG. 7 is a side view of a block according to another embodiment.
FIG. 8 is a side view of a block according to another embodiment.
FIG. 9 is a side view of a block according to another embodiment.
[Explanation of symbols]
10 Pneumatic tire 12 Tread 14 Main groove 16 Lug groove 18 Block (Block-shaped land)
20 Horizontal sipe (Sipe)
22 Straight portion 24 Wavy portion (first wavy portion)
24a 1st convex part 24b 2nd convex part 26 Wavy part (2nd wavy part)
26a 2nd convex part 26b 1st convex part

Claims (1)

A block land portion divided into a plurality of blocks by a main groove formed along a circumferential direction of the cylindrical tread and a lug groove formed in a direction intersecting the main groove; In particular, a pneumatic tire including at least one sipe extending in the tire width direction, wherein the sipe is in the depth direction of the block land portion,
When the linear portion formed linearly on the tread surface side and the circumferential direction of the tread are defined as the first circumferential direction and the second circumferential direction, respectively, according to the rotational direction, the first circumferential direction is located inside the block-shaped land portion. A wavy portion having at least a convex first convex portion and a second convex portion convex in the second circumferential direction;
In the depth direction of the block-shaped land portion, a first wavy portion having the first convex portion on the tread surface side and a second convex portion on the sipe bottom side, and the second convex portion on the tread surface side and the second convex portion on the sipe bottom side. The second wavy portion having one convex portion is provided at a different position in the sipe longitudinal direction ,
The air characterized in that the straight portion and the wavy portion are open on both side surfaces in the tire width direction of the block-shaped land portion, and the sipe wall surface is formed by a surface that smoothly continues between the both side surfaces. Enter tire.

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