JP2000006618A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve wet grip performance, brake on the ice, driving performance and uneven wear resisting performance by restraining a pneumatic tire from having its grounding property deterioration when the number of sipes are increased. SOLUTION: A block-shaped land part 18 is formed with a plurality of sipes 20 zigzag extending along the tire in the cross direction. The sipes 20 being formed with slants 20C on the intermediate portions in the depth direction have larger contact area on the sipe walls than the sipes extending straight in the depth direction so that the sipe walls facing each other easily come into contact just by the block-shaped land part 18 receiving compressional deformation. For this reason, sipe contacting force comes still more stronger when the block deforms and the block-shaped land part 18 can be restrained from collapsing more effectively than the conventional ones at the time of braking drive when the number of sipes are increased, which serve to improve wet grip performance, on-the-ice-braking and uneven wear resisting performance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to an improvement of a pneumatic tire having excellent running performance on ice and snow roads.

[0002]

2. Description of the Related Art With the ban on the use of spike tires, various improvements in treads have been made in search of better studless tires.

[0003] As a feature almost common to this studless tire, a large number of sipes extending straight in the depth direction are provided on the tread.

The sipe divides the tread surface into a number of blocks, and the shape of the sipe in the width direction has been studied in order to improve the friction coefficient (μ) on ice (edge effect) by the corners of the blocks.

[0005]

In order to achieve a higher friction coefficient on ice in the prior art, there are a method of increasing the number of sipes and a method of improving the water removal function.

[0006] If the number of sipes is increased in the prior art, the grounding property is deteriorated due to a decrease in the block rigidity, so that such an effect cannot be expected. In addition, uneven wear (heel and toe wear) due to deterioration of the grounding property occurs.

[0007] The present invention has been made in view of the above-mentioned problems, and it is possible to suppress deterioration of the grounding property when the number of sipes is increased, thereby improving wet grip performance, braking drive performance on ice, and uneven wear resistance. It is an object of the present invention to provide a pneumatic tire that can be used.

[0008]

According to the first aspect of the present invention,
Including a plurality of circumferentially extending main grooves and a block-shaped land portion divided by a number of lug grooves intersecting these main grooves,
In the pneumatic tire provided with a tread in which each of the block-shaped land portions has a plurality of sipes, the sipes have an amplitude in a direction perpendicular to the sipe longitudinal direction at least on the tread side, and the tread when bisected in the depth direction. The first part on the side and the second part on the sipe bottom part are displaced in the sipe width direction, and the first part and the second part extend in a direction crossing the tire radial direction. It is characterized by being connected via a third part.

Next, the operation of the pneumatic tire according to the first aspect will be described.

In general, since the groove width of the sipe is narrow, when the block-shaped land portion comes into contact with the ground during driving braking or the like, the sipe wall surfaces come into contact with each other and the fall of the small land portion divided by the sipe is suppressed to some extent. Is done.

In the sipe of the pneumatic tire according to the present invention, the first portion on the tread side and the second portion on the sipe bottom are displaced in the tire circumferential direction, and the first and second portions are displaced from each other. Are connected via a third portion extending in a direction intersecting the tire radial direction, so that the sipe has a bent portion at a middle portion in the depth direction.

The sipe having the third portion extending in the direction intersecting the tire radial direction at the middle portion in the depth direction as in the present invention has a greater contact with the sipe wall surface than the sipe extending straight in the depth direction. Since the area is increased, the effect of suppressing the falling of the block-shaped land portion at the time of touchdown is high.

Further, the third portion extending in a direction intersecting with the tire radial direction can easily contact the sipe wall surfaces when the block-shaped land portion is subjected to compressive deformation. The force is further increased, and the effect of suppressing the falling of the block-shaped land portion is enhanced as compared with the sipe extending straight in the depth direction.

As described above, according to the present invention, even when the number of sipes is increased, it is possible to suppress the falling of the block-shaped land portion at the time of touching down even when the number of sipes is increased.

That is, in the pneumatic tire of the present invention, the increase in the amount of deformation of the block-shaped land portion when the number of sipes is increased can be reduced, so that the deterioration of the ground contact can be suppressed.
In the case of the sipe extending in the tire width direction, the wet grip performance, the braking drive performance on ice, and the uneven wear resistance can be improved, and in the case of the sipe extending in the tire circumferential direction, the cornering performance can be improved.

According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the first portion and the second portion have a zero amplitude at a connection portion with the third portion. It is characterized by.

Next, the operation of the pneumatic tire according to claim 2 will be described.

In a sipe extending linearly in the tire width direction, an edge length appearing on a tread is not sufficient, so that a water film between the sipe and a road surface cannot be cut sufficiently.

On the other hand, in a sipe having an amplitude on the block surface and a constant amplitude in the depth direction (for example, a general zigzag sipe), a water film is cut in the amplitude shape of the block surface, and a road surface is formed inside the sipe. Although it is possible to suck up the water between the block, the water sucked up particularly at the center of the block cannot be smoothly drained to the outside of the block.

That is, comparing a sipe having an amplitude like a zigzag sipe and a straight sipe extending linearly, the straight sipe has a smoother flow of water in the sipe (the longitudinal direction of the sipe), Water can be drained smoothly from the side of the block.

In the sipe of the pneumatic tire according to the second aspect, since the amplitude of the sipe becomes zero at a connection portion with the third portion, when the sipe extends along the tire width direction, a water film is formed on the block surface. And the water sucked into the sipe can be smoothly drained from the block side surface to the main groove through the portion where the amplitude of the sipe becomes zero and the vicinity thereof.

In the third portion, it is preferable from the viewpoint of drainage that the amplitude is zero over the whole, that is, it extends straight in the tire width direction.

According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, in the block-shaped land portion, the first region is located on one side of a land center. The second portion is displaced toward the one side from the portion, and the second portion is displaced toward the other side rather than the first portion in a region on the other side with respect to a land center. It is characterized by having.

Next, the operation of the pneumatic tire according to the third aspect will be described.

For example, as shown in FIG.
When the input indicated by the arrow F acts on the tread surface of the block-shaped land portion 100 on which the sipe 102 having the second portion 102B and the second portion 102B is formed, the small blocks 100A, 100
B leans on a small block adjacent in the direction of arrow F (small block 100A to small block 100B, small block 100B to small block 100C), small block 1
00A and the wall of the sipe 102 between the small block 100B and the small block 100B contact each other,
And the sipe wall surface of the sipe 102 comes into contact.

Due to the contact force when the walls of the sipe 102 come into contact, the deformation of the small blocks 100A and 100B is suppressed.

Although the small block 100C receives the contact force by the small block 100B, the deformation is suppressed because the width near the base of the block is large and the rigidity is high. If the rigidity of the small block 100C is not sufficient, it is supported by the small blocks 100D and 100E which do not fall down even if an input is received.
The deformation of the small blocks 100D and 100E is also suppressed.

Therefore, in the pneumatic tire according to the third aspect, the function of suppressing deformation of the block-shaped land portion is further improved.

According to a fourth aspect of the present invention, in the pneumatic tire according to the first or second aspect, when the sipes are viewed adjacent to each other in the block-like land portion, the second The parts are characterized in that they are displaced in opposite directions.

According to a fifth aspect of the present invention, in the pneumatic tire according to any one of the first to fourth aspects,
The third portion is characterized in that the depth is different for each sipe.

Next, the operation of the pneumatic tire according to the fifth aspect will be described.

In the pneumatic tire according to the fifth aspect, in the plurality of sipes formed on the block-shaped land portion, the third
Since the depth of the portion is different for each sipe, the effect of suppressing the falling can be enhanced as compared with the block-like land portion in which all the third portions are set to the same depth.

According to a sixth aspect of the present invention, in the pneumatic tire according to any one of the first to fourth aspects,
The third portion is provided at a position deeper as a sipe near the center of the land portion.

Next, the operation of the pneumatic tire according to claim 6 will be described.

In the pneumatic tire according to the sixth aspect, in the plurality of sipes formed on the block-like land portion, the third
Is located as deep as the sipe near the center of the land,
The bending rigidity of the block-shaped land gradually increases from the center of the land toward the end of the block-shaped land. Can be increased.

According to a seventh aspect of the present invention, in the pneumatic tire according to any one of the first to sixth aspects,
The sipe extends in the tire width direction.

Next, the operation of the pneumatic tire according to claim 7 will be described.

In the case where a sipe extending along the tire width direction is provided in the block-shaped land portion as in the pneumatic tire according to the seventh aspect, the small land portion divided by the sipe extends in the tire circumferential direction. The fall can be suppressed, and the performance when traveling straight ahead, specifically, the wet grip performance, the braking drive performance on ice, and the uneven wear resistance performance can be improved.

The invention according to claim 8 provides the pneumatic tire according to any one of claims 2 to 7,
The relationship between the depth A of the portion where the amplitude becomes zero at a position on the bottom side of the tread surface of the sipe and the depth B of the sipe is 1 /
It is characterized in that 10 <A / B <1/2.

Next, the operation of the pneumatic tire according to claim 8 will be described.

If A / B <1/10, the portion where the amplitude becomes zero in the early stage of wear disappears, and there is a possibility that heel and toe wear may occur due to a decrease in block rigidity in the middle stage of wear.

On the other hand, if 2/3 <A / B, the rigidity of only the base portion (base portion) of the small land portion divided by the sipe is reduced, and deformation is concentrated near the base portion, so that the block shape is obtained. The falling deformation of the land cannot be suppressed. Therefore, heel-and-toe wear may occur from the beginning of wear.

Therefore, it is preferable that 1/10 <A / B <1/2.

[0044]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of a pneumatic tire according to the present invention will be described below with reference to FIGS. 1 (A) and 1 (B).
And FIG.

The internal structure of the pneumatic tire 10 according to the present embodiment is the structure of a general radial tire, and a description of the internal structure will be omitted.

As shown in FIG. 2, the tread 12 of the pneumatic tire 10 of the present embodiment has a tire circumferential direction (arrow S).
), And a plurality of lug grooves 16 intersecting with the main grooves 14 are formed, and the block-shaped land portion 18 is divided by these main grooves 14 and the lug grooves 16. I have.

In this embodiment, both the main groove 14 and the lug groove 16 are straight. However, the main groove 14 is a known groove such as a zigzag shape, a crank shape and the like, which extends in the tire circumferential direction at a predetermined interval on the left and right sides. Similarly, the lug groove 16 may have another shape such as a crank shape or a concave groove.

As shown in FIGS. 1A and 2, the block-shaped land portion 18 of the present embodiment has the same length L1 in the tire circumferential direction and the same length L2 in the tire width direction (arrow W direction). The shape is a square shape, but may be another shape such as a rectangle.

As shown in FIG. 2, a plurality of sipes 20 extending in the tire width direction and crossing the block-like land portion 18 are formed on the block-like land portion 18, and each block-like land portion 18 It is divided into a plurality of small blocks (land areas) 18B by a plurality of sipes 20.

As shown in FIG. 1A, the sipe 20 of this embodiment is a so-called zigzag sipe (triangular wave shape) having an amplitude a, and the amplitude a is set to be constant from the tread surface 18A to the bottom of the sipe.

If the sipe 20 is a sipe having an amplitude a on the tread surface 18A, the shape that appears on the tread surface 18A is not limited to a zigzag shape, but may be another shape such as a sine curve.

As shown in FIGS. 1A and 1B, the sipe 20 of the block-shaped land portion 18 extends in a direction substantially perpendicular to the tread surface 18A and contacts the first portion 20A.
And extends substantially perpendicularly to the tread 18A, and the tread 1
8A, and a second portion 20B offset to the side away from the center of the block-shaped land portion 18 in the tire circumferential direction with respect to the first portion 20A, and each of the first portion 20A and the second portion 20B adjacent to each other. And an inclined portion 20C extending obliquely downward from the first portion 20A toward the second portion 20B.

In this embodiment, the sipe depth B of each sipe 20 is set to be the same, and the center position of the inclined portion 20C measured in a direction perpendicular to the tread surface 18A (see FIG. 1).
The dimensions A up to the position indicated by the dashed line in (A) are all set to the same dimension.

The relationship between the sipe depth B and the dimension A is as follows.
1/10 <A / B <2/3.

Next, the operation of the pneumatic tire 10 of the present embodiment will be described.

Since the sipe 20 of the pneumatic tire 10 of the present embodiment has the inclined portion 20C at the middle part in the depth direction, the sipe 20 is compared with a sipe extending straight in the depth direction (condition of the same depth as the sipe 20). The contact area of the wall surface increases, and the action of suppressing the falling of the block-shaped land portion 18 during the braking operation is high.

Further, in the inclined portion 20C, even when the block-shaped land portion 18 is only subjected to compressive deformation, opposing sipe wall surfaces easily come into contact with each other (that is, the inclined portion 20C is in a direction intersecting the compression direction). Therefore, the sipe contact force at the time of block deformation is further increased, and the block-shaped land portion 18 of the present embodiment is less likely to fall down as compared with a conventional block-shaped land portion having a sipe without the inclined portion 20C. .

In the pneumatic tire 10 of the present embodiment, the sipe is formed by the increase in the contact area of the sipe wall surface due to the provision of the inclined portion 20C and the increase in the sipe contact force at the inclined portion 20C when subjected to compressive deformation. Even when the number is increased, the falling of the block-shaped land portion 18 during the braking drive can be suppressed more than before.

As described above, in the pneumatic tire 10 according to the present embodiment, since the amount of deformation of the block-shaped land portion 18 when the number of sipes is increased can be reduced, and deterioration of the contact property can be suppressed, the wet grip performance and The braking drive performance on ice and the uneven wear resistance performance can be improved.

When A / B <1/10, the effect of the present invention is lost because the inclined portion 20C disappears in the early stage of wear, and heel-and-toe wear occurs due to a decrease in block rigidity in the middle stage of wear. Would.

On the other hand, when 2/3 <A / B, sipe 2
The rigidity of only the base portion (base portion) of the small block divided by 0 is reduced, and the deformation concentrates near the base, so that the falling deformation of the block-like land portion 18 cannot be suppressed. For this reason, heel-and-toe wear occurs from the beginning of wear.

In this embodiment, the block-shaped land portion 1 is used.
Although eight sipe 20 are formed on the block 8, six sipe 20 may be formed on the block land 18 as shown in FIG.
The number of 0s formed is not limited to the number in the present embodiment.

Further, as shown in FIG.
In one block-shaped land portion 18, the position of the inclined portion 20C may be set deeper toward the center portion. Thereby, the block-like land portion 1 is smaller than the case where the position of the inclined portion 20C is set to the same depth (the same number of sipes are compared between the same ones).
8 can be suppressed and the ground contact area can be secured, so that wet grip performance, braking drive performance on ice, and uneven wear resistance can be maintained at a high level.

Further, the sipe 20 does not cross the block-shaped land portion 18 as shown in FIG. Or
It is also possible to appropriately use a so-called transverse sipe such as the sipe 20 and a dead end sipe. [Second Embodiment] Next, a second embodiment of the pneumatic tire according to the present invention will be described with reference to FIG. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 5A, each block-shaped land portion 18 is formed with a plurality of lateral sipes 24 extending in the tire width direction (the direction of the arrow W).

The sipe 24 formed in each block-shaped land portion 18 extends in a direction substantially perpendicular to the tread surface 18A and contacts a first portion 24A that contacts the tread surface 18A, and extends in a direction substantially perpendicular to the tread surface 18A. A second portion 24B, which is spaced from the tread surface 18A and is offset from the first portion 24A to a side away from the centerline 19 in the tire circumferential direction of the block-shaped land portion 18, a first portion 24A and a second portion 24B; From the first portion 24A to the second portion 24B.
Inclined portion 24 that extends diagonally downward toward
C.

The amplitude a of the first portion 24A gradually decreases from the tread surface 18A toward the sipe bottom surface, and the amplitude a becomes zero at the contact point with the inclined portion 24C.

In the inclined portion 24, the amplitude a is zero throughout.

The amplitude a of the second portion 24B at the contact point with the inclined portion 24 is zero, but the amplitude a gradually increases toward the bottom of the sipe.

In this embodiment, the sipe depth B of each sipe 24 is all set to be the same, and the dimension A up to the center position (the position shown by the dashed line) of the inclined portion 24C is all set to the same size. I have.

In this embodiment, the relationship between the sipe depth B and the dimension A is set to 1/10 <A / B <1/2.

Next, the operation of the pneumatic tire 10 of the present embodiment will be described.

The sipe 24 of the pneumatic tire 10 of the present embodiment also has the inclined portion 24C at the middle part in the depth direction, so that the contact area of the sipe wall surface is increased as compared with the sipe extending straight in the depth direction, and braking is performed. The effect of suppressing the falling of the block-shaped land portion 18 during driving is high.

Further, in the inclined portion 24C, even when the block-shaped land portion 18 is only subjected to compression deformation, opposing sipe wall surfaces easily come into contact with each other (that is, the inclined portion 24C is in a direction intersecting the compression direction). Therefore, the sipe contact force at the time of block deformation is further increased, and the block-shaped land portion 18 of the present embodiment is less likely to fall as compared with a conventional block-shaped land portion having a sipe without the inclined portion 24C. .

The pneumatic tire 10 of the present embodiment also has a sipe due to an increase in the contact area of the sipe wall surface due to the provision of the inclined portion 24C and an increase in the sipe contact force at the inclined portion 24C when subjected to compressive deformation. Even when the number is increased, the falling of the block-shaped land portion 18 during the braking drive can be suppressed as compared with the related art.

As described above, also in the pneumatic tire 10 of the present embodiment, the increase in the amount of deformation of the block-shaped land portion 18 when the number of sipes is increased can be reduced, and the deterioration of the contact property can be suppressed. In addition, the braking drive performance on ice and the uneven wear resistance performance can be improved.

Further, the pneumatic tire 10 of the present embodiment
Then, since the amplitude a of the sipe 24 becomes zero at the inclined portion 24C, the water film between the sipe 24 and the road surface is cut off by the edge of the sipe 24 appearing on the tread surface 18A, and the water sucked up into the sipe 24 has an amplitude a of zero. It is possible to smoothly drain water from the side surface of the block-shaped land portion 18 (the longitudinal end of the sipe 24) to the main groove 14 via the inclined portion 24C extending linearly in the tire width direction. Performance is improved.

If A / B <1/10, the effect of the present invention is lost because the inclined portion 24C disappears in the early stage of wear, and heel-and-toe wear occurs due to a decrease in block rigidity in the middle stage of wear. Would.

On the other hand, when 1/2 <A / B, the inclined portion 2
Since 4C is far from the tread surface 18A and drainage performance is reduced, the sipe 24 cannot sufficiently suck up water between the road surface and the effect of the present invention cannot be expected.

In the sipe 24, as shown in FIG. 6, the position of the inclined portion 24C may be set deeper toward the center of one block-shaped land portion 18. Thereby, the block-like land portion 1 is smaller than the case where the position of the inclined portion 24C is set to the same depth (the number of sipes is the same for the same number).
8 can be suppressed and the ground contact area can be secured, so that wet grip performance, braking drive performance on ice, and uneven wear resistance can be maintained at a high level.

Although not shown, the sipe 24 may be arranged so that the second portion 24B is alternately arranged between the adjacent sipe 24.

Note that the amplitude a of the sipe of the above-described embodiment is
Is preferably 1 to 3 mm. When the amplitude a is less than 1 mm, the effect is reduced because the contact area of the sipe wall surface becomes small. On the other hand, if the amplitude a is larger than 3 mm, the sipe interval is widened, so that the number of sipe formed on the block-shaped land portion decreases.

In the above embodiment, a sipe extending in the tire width direction is formed on the block-shaped land portion, but a sipe extending in the tire circumferential direction may be formed on the block-shaped land portion.

By forming the sipe of the present invention extending in the tire circumferential direction on the block-shaped land portion, the cornering performance can be improved as compared with a conventional tire having a straight sipe. [Test Example] In order to confirm the effect of the present invention, a conventional pneumatic tire and a pneumatic tire of an embodiment to which the present invention was applied were prepared, and tests were performed on the braking performance on ice and the heel and toe wear performance. Was. All tires used had a tire size of 185 / 70R14.

The braking performance on ice is measured by measuring the distance from the point where the tire was applied to the vehicle and stopping at a speed of 20 km / h with the tire mounted on the vehicle, and the reciprocal of the distance was used as an index on the ice braking performance. (The conventional example is assumed to be 100). The larger the value, the better the performance. The measurement was performed twice each for a new product and 50% wear.

The heel and toe wear performance was 20,000
The amount of step difference due to heel-and-toe wear after traveling km was measured, and the reciprocal thereof was shown as an index (the conventional example was taken as 100) and shown in Table 1. The larger the value, the better the performance.

Example 1 A pneumatic tire provided with a block-shaped land portion shown in FIG. 1 on a tread, the block-shaped land portion having a tire circumferential length L1 of 20 mm and a tire width direction length L2 of 20 mm. The height H is 20 mm and the height H is 10 mm. The sipe has a sipe depth B of 7 mm, a dimension A from the tread surface to the center of the inclined portion of 3.5 mm, and an amplitude a of 1.5 mm.

Embodiment 2 A pneumatic tire provided with a block-shaped land portion shown in FIG. 5 on a tread, the size of the block-shaped land portion is the same as that of the embodiment 1, and the sipe has a depth B. 7 mm, the dimension A from the tread to the center of the inclined portion is 3.5 mm, and the amplitude a (maximum part) is 1.5 mm.

Conventional Example: As shown in FIG.
This is a pneumatic tire in which a straight sipe 72 is formed on a block-shaped land portion 70 having the same size as that of the tire 2. The sipe depth B of the straight sipe 72 is 7 mm, which is the same as in the embodiment.

[0090]

[Table 1]

From the results shown in Table 1, it was clarified that the tires 1, 2, and 3 of the present invention had better braking performance on ice than the conventional tires.

The reason why the tire of Example 2 has a higher braking performance on ice than that of Example 1 is that the drainage property is high at the slope of the sipe.

The reason why the tire of Example 1 has high braking performance on ice during wear is that the edge length of the block surface is longer than that of the other tires.

[0094]

As described above, the pneumatic tire according to the first aspect has the above-described structure. Therefore, when the pneumatic tire has a sipe extending in the tire width direction, the wet grip performance, the braking drive performance on ice, This has an excellent effect that the wear performance can be improved, and when a sipe extending in the tire circumferential direction is provided, the cornering performance can be improved.

Since the pneumatic tire according to the second aspect is configured as described above, the water sucked into the sipe is smoothly drained from the side surface of the block to the main groove through the portion where the amplitude of the sipe becomes zero and the vicinity thereof. This has an excellent effect that the wet grip performance and the on-ice braking drive performance can be further improved.

Since the pneumatic tire according to the third aspect has the above-described structure, the effect of suppressing deformation is large, so that the pneumatic tire has an excellent effect that the on-ice braking drive performance and the wet performance can be improved.

Since the pneumatic tire according to the fifth aspect has the above-described configuration, the effect of suppressing the falling can be enhanced more than the block-like land portion in which the third portions are all set to the same depth, and the contact area can be reduced. Therefore, when a sipe extending in the tire width direction is provided, wet grip performance, braking drive performance on ice, and uneven wear resistance performance can be maintained at a high level, and when a sipe extending in the tire circumferential direction is provided, It has an excellent effect that the cornering performance can be maintained at a high level.

Since the pneumatic tire according to the sixth aspect has the above-described structure, the effect of suppressing the fall can be enhanced as compared with the block-shaped land portion in which all the third portions are set to the same depth, and the ground contact area can be reduced. Therefore, when a sipe extending in the tire width direction is provided, wet grip performance, braking drive performance on ice, and uneven wear resistance performance can be maintained at a high level, and when a sipe extending in the tire circumferential direction is provided, It has an excellent effect that the cornering performance can be maintained at a high level.

Since the pneumatic tire according to the seventh aspect has the above-described configuration, the wet grip performance mainly when the vehicle is traveling straight,
There is an excellent effect that the braking drive performance on ice and the uneven wear resistance performance can be improved.

Since the pneumatic tire according to the eighth aspect has the above-described structure, it has an excellent effect that generation of heel-and-toe wear can be reliably suppressed.

[Brief description of the drawings]

FIG. 1A is a perspective view of a block-shaped land portion of a pneumatic tire according to a first embodiment, and FIG. 1B is a side view of the block-shaped land portion.

FIG. 2 is a plan view showing a part of a tread of the pneumatic tire according to the first embodiment of the present invention.

FIG. 3 is a side view showing a modification of the block-shaped land portion of the pneumatic tire according to the first embodiment.

FIG. 4 is a side view showing still another modified example of the block-shaped land portion of the pneumatic tire according to the first embodiment.

FIG. 5A is a perspective view of a block-shaped land portion of a pneumatic tire according to a second embodiment, and FIG. 5B is a side view of the block-shaped land portion.

FIG. 6 is a side view showing a modification of the block-shaped land portion of the pneumatic tire according to the second embodiment.

FIG. 7 is a perspective view showing a block-shaped land portion of a pneumatic tire according to a conventional example.

FIG. 8 is a side view of a block-shaped land portion for explaining the operation of the pneumatic tire according to claim 3.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Tread 14 Main groove 16 Lug groove 18 Block-shaped land portion 18A Tread surface 20 Sipe 20A First part (first part) 20B Second part (second part) 20C Inclined part (third part) 24 Sipe 24A First part (first part) 24B Second part (second part) 24C Inclined part (third part)

Claims (8)

[Claims] 1. A tread having a plurality of circumferentially extending main grooves and a block-shaped land portion divided by a number of lug grooves intersecting these main grooves, wherein the block-shaped land portion has a plurality of sipes. In the pneumatic tire provided, the sipe has an amplitude in a direction perpendicular to the sipe longitudinal direction at least on the tread side, and a first portion on the tread side and a second portion on the sipe bottom side when divided in the depth direction. The first portion and the second portion are connected via a third portion extending in a direction intersecting the tire radial direction. And pneumatic tires. 2. The pneumatic tire according to claim 1, wherein the first portion and the second portion have a zero amplitude at a connection portion with the third portion. 3. In the block-shaped land portion, in a region on one side of a land portion center, the second portion is displaced to the one side more than the first portion, and the land portion center is In the area on the other side of the boundary, the second portion is more
3. The pneumatic tire according to claim 1 or 2, wherein the portion is displaced to the other side. 4. The block-shaped land portion according to claim 1, wherein the second portions are displaced in directions opposite to each other when the sipes are viewed adjacent to each other. A pneumatic tire according to claim 1. 5. The pneumatic tire according to claim 1, wherein the third portion has a different depth for each sipe. 6. The apparatus according to claim 1, wherein the third portion is provided at a position deeper as the sipe is closer to the center of the land.
The pneumatic tire according to any one of claims 4 to 4. 7. The pneumatic tire according to claim 1, wherein the sipe extends along a tire width direction. 8. The relationship between the depth A of a portion where the amplitude becomes zero at a position on the bottom side of the tread surface of the sipe and the depth B of the sipe is 1/10 <A / B <1/2. The pneumatic tire according to any one of claims 2 to 7, wherein