JP2024061489A - tire - Google Patents

Abstract

[Problem] To provide a tire that can sufficiently improve snow and ice performance while ensuring wear resistance. [Solution] In a tire 1 of the present invention, a block has at least three sipes extending in the tire width direction, at least one side in the tire width direction opening into a circumferential groove, and the at least three sipes are composed of a first sipe 18a and a second sipe 18b, the first sipe 18a is a linear vertical flask sipe that extends linearly in a tread surface view, and has a linear portion extending perpendicularly from the tread surface 10 in a cross section in the sipe depth direction, and has a flask shape with a widened portion on the sipe bottom side, and the second sipe 18b is a wavy flask sipe that extends in a wavy manner with three or more peaks on at least one side in a tread surface view, and has a flask shape with a widened portion on the sipe bottom side in a cross section in the sipe depth direction. [Selected Figure] Figure 1

Description

The present invention relates to a tire.

Many technologies have been developed to improve the performance of tires on snow and ice. For example, Patent Document 1 discloses a tire that improves its performance on ice by improving the configuration of three sipes that extend in the tire width direction and are provided on the blocks of the tread surface.

International Publication No. 2019/111757

However, particularly in heavy-duty tires, there are cases where sufficient snow and ice performance cannot be obtained depending on the road surface, even with the sipe configuration as shown in Patent Document 1. Also, in tires, care must be taken to ensure that the provision of sipes in the blocks does not reduce wear resistance.

Therefore, the objective of the present invention is to provide a tire that can sufficiently improve performance on snow and ice while maintaining wear resistance.

The above problem can be solved by the following means:

(1) The tire of the present invention is
A tire having blocks defined by circumferential grooves and lug grooves formed on a tread surface,
The block has at least three sipes extending in the tire width direction, at least one side in the tire width direction being open to the circumferential groove,
The at least three sipes include a first sipe and a second sipe,
The first sipe is a linear vertical flask sipe that extends linearly when viewed from the tread surface, and has a linear portion extending vertically from the tread surface when viewed in a cross section in the sipe depth direction, and has a flask shape having an expanded portion on the sipe bottom side,
The second sipe is characterized in that it is a wavy flask sipe that extends in a wavy manner with at least three or more peaks on each side when viewed from the tread surface, and has a flask-like shape with a widened portion on the bottom side of the sipe when viewed in a cross-section in the sipe depth direction.
According to the tire of the present invention, it is possible to sufficiently improve the performance on snow and ice while ensuring the wear resistance.

(2) In the tire according to (1),
Of the at least three sipes in each block, it is preferable that only a sipe on a central side in the tire circumferential direction within the block is the first sipe.
In this case, it is possible to further improve the ice and snow performance and the wear resistance, and to suppress variations in the ice and snow performance and the wear resistance caused by differences in the mounting direction of the tire on the vehicle when in use.

(3) In the tire according to (2),
Of the at least three sipes in each block, it is preferable that only one sipe located on a central side in the tire circumferential direction within the block is the first sipe.
In this case, it is possible to achieve a better balance between snow and ice performance and abrasion resistance.

(4) In the tire according to (2) or (3),
In a tread surface view, it is preferable that an average distance in the tire circumferential direction between the first sipe and the second sipe is shorter than an average distance in the tire circumferential direction between the second sipe and an edge of the block in the tire circumferential direction.
In this case, it is possible to further improve the wear resistance performance, and to further suppress the variation in wear resistance performance due to differences in the mounting direction of the tire on a vehicle during use.

(5) In any one of the tires (1) to (4),
The first sipes and the second sipes are provided in a plurality of blocks adjacent to each other in a tire width direction,
It is preferable that, between two of the blocks adjacent in the tire width direction, the projection directions of the ridges of the second sipes are on opposite sides in the tire circumferential direction.
In this case, it is possible to suppress variations in ice and snow performance caused by differences in the direction in which the tire is mounted on the vehicle when in use.

(6) In any one of the tires (1) to (5),
The first sipe is a protruding sipe having a protrusion protruding from a sipe wall on one side of the first sipe and extending in a sipe depth direction,
It is preferable that the protrusion of the first sipe has a length in the sipe depth direction that is equal to or greater than half the sipe depth, and extends from the tread surface in the sipe depth direction.
In this case, the snow and ice performance can be further improved.

(7) In the tire according to (6),
In the block, it is preferable that a protruding direction of the projection of the first sipe from a sipe wall is opposite to a protruding direction of the ridge of the second sipe in the tire circumferential direction.
In this case, it is possible to suppress variations in ice and snow performance caused by differences in the direction in which the tire is mounted on the vehicle when in use.

The present invention provides a tire that can sufficiently improve snow and ice performance while maintaining wear resistance.

1 is a development view showing a tread surface of a tire according to one embodiment of the present invention. FIG. 2 is an enlarged plan view for explaining an example of a block in the tire of FIG. 1 . FIG. 2 is an enlarged plan view for explaining a first sipe in the tire of FIG. 1 . 2 and 3A in cross section taken along the line X1-X1. This is a cross-sectional view taken along the line X2-X2 of FIG. 10 is a schematic plan view for explaining the relationship between the direction in which a protrusion in a first sipe protrudes from a sipe wall and the direction in which a crest in a second sipe protrudes. FIG.

The tire according to the present invention can be used as any type of tire, for example, as a passenger car tire, a truck/bus tire, or a construction/mining vehicle tire, and is particularly suitable for use as a heavy-duty tire such as a truck/bus tire or a construction/mining vehicle tire, and particularly as a truck/bus tire.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a tire according to the present invention will be described by way of example with reference to the drawings.
The same components and parts are designated by the same reference numerals in each drawing.
In this specification, the term "tire circumferential direction" refers to the direction in which the tire rotates about the tire's axis of rotation, and the term "tire width direction" refers to the direction parallel to the tire's axis of rotation. In some drawings, the tire circumferential direction is indicated by the symbol "CD" and the tire width direction is indicated by the symbol "WD".
In this specification, the side closer to the tire equatorial plane CL along the tire width direction is referred to as the "inner side in the tire width direction," and the side farther from the tire equatorial plane CL along the tire width direction is referred to as the "outer side in the tire width direction."
Furthermore, in this specification, "extending in the tire circumferential direction" means extending with at least a tire circumferential component, and "extending in the tire width direction" means extending with at least a tire width direction component.

Unless otherwise specified, the positional relationship and dimensions of each element are measured in a standard state in which the tire is mounted on an applicable rim, inflated to the specified internal pressure, and unloaded. In this specification, the term "tread surface" refers to the outer peripheral surface of the tire that comes into contact with the road surface when the tire is mounted on an applicable rim, inflated to the specified internal pressure, and under maximum load, and the edge of the tread surface in the tire width direction is called the "tread edge (TE)." In this specification, "tread surface view" refers to a planar view of the tread surface when the tread surface is developed on a flat surface.

In this specification, the term "applicable rim" refers to the standard rim for the applicable size that is described or will be described in the future in the industrial standards in effect in the region in which the tire is manufactured and used, such as the JATMA Yearbook of the Japan Automobile Tire Manufacturers Association (JATMA) in Japan, the Standards Manual of the European Tire and Rim Technical Organization (ETRTO) in Europe, and the Yearbook of the Tire and Rim Association, Inc. (TRA) in the United States. For sizes not specified in these industry standards, it refers to a rim with a width that corresponds to the bead width of a pneumatic tire. "Applicable rim" includes current sizes as well as sizes that will be specified in the aforementioned industry standards in the future. Examples of "sizes that will be specified in the future" include sizes specified as "FUTURE DEVELOPMENTS" in the 2013 edition of ETRTO.

In this specification, "prescribed internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel in the applicable size and ply rating as described in the aforementioned industrial standards such as the JATMA YEAR BOOK, and in the case of a size not described in the aforementioned industrial standards, refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle on which the tire is mounted. Also, in this specification, "maximum load" refers to the load corresponding to the maximum load capacity of the tire in the applicable size as described in the aforementioned industrial standards, or in the case of a size not described in the aforementioned industrial standards, refers to the load corresponding to the maximum load capacity specified for each vehicle on which the tire is mounted.

In this specification, "groove width" is measured in a direction parallel to the tread surface in a cross section perpendicular to the extension direction of the groove on the tread surface in the above-mentioned reference state. The groove width may be constant or may vary in a direction perpendicular to the tread surface. However, in this specification, unless otherwise specified, "groove width" refers to the groove width on the tread surface. Also, in this specification, "groove depth" is measured in a direction perpendicular to the tread surface in the above-mentioned reference state.

In this specification, the term "sipe" refers to a sipe having a width of 2 mm or less over an area of 50% or more of the sipe depth in the above-mentioned standard state. Here, in this specification, the term "sipe width" refers to a cross section perpendicular to the extension direction of the sipe on the tread surface in the above-mentioned standard state, measured in a direction parallel to the tread surface, excluding the protrusion portion described below. The sipe width may be constant or may vary in a direction perpendicular to the tread surface. However, in this specification, unless otherwise specified, the term "sipe width" refers to the sipe width on the tread surface. In addition, in this specification, the term "sipe depth" refers to a direction perpendicular to the tread surface in the above-mentioned standard state, and the term "sipe depth direction" refers to a direction perpendicular to the tread surface for the sipe in the above-mentioned standard state. Furthermore, in this specification, the term "sipe longitudinal direction" refers to the extension direction of the sipe (more specifically, the sipe center line) on the tread surface, and the term "sipe width direction" refers to a direction perpendicular to the sipe longitudinal direction on the tread surface. In some drawings, the sipe longitudinal direction is indicated by the symbol "SLD" and the sipe width direction is indicated by the symbol "SWD."

FIG. 1 is a development view showing a tread surface of a tire according to one embodiment of the present invention.
A tire 1 according to one embodiment of the present invention shown in FIG. 1 is a pneumatic radial tire for trucks and buses.

Although detailed description is omitted, the tire 1 of the embodiment described below can have a general tire structure, for example, a sidewall portion extending radially outward from each of a pair of bead portions, a tread portion spanning between both sidewall portions, a carcass having a carcass ply made of, for example, organic fiber cords or steel cords that extends from one bead portion through the tread portion to the other bead portion, and a belt having a belt layer made of, for example, steel cords, disposed between the carcass and the tread rubber of the tread portion.

1, the tire 1 of this embodiment has a tread surface 10 formed with a pair of inner circumferential main grooves (circumferential grooves) 11 arranged on both sides of the tire equatorial plane CL in the tire width direction, and a pair of outer circumferential main grooves (circumferential grooves) 12 arranged on both sides of the pair of inner circumferential main grooves 11 in the tire width direction. The inner circumferential main groove 11 and the outer circumferential main groove 12 each extend linearly along the tire circumferential direction (i.e., at an angle of 0° with respect to the tire circumferential direction) continuously around the entire tire circumference.
The groove depths of the inner circumferential main groove 11 and the outer circumferential main groove 12 are the same (e.g., about 20 mm). The groove widths of the inner circumferential main groove 11 and the outer circumferential main groove 12 are the same. However, the groove depths of the inner circumferential main groove 11 and the outer circumferential main groove 12 may be different from each other, and the groove widths of the inner circumferential main groove 11 and the outer circumferential main groove 12 may be different from each other.

The tread surface 10 is divided into a center block row 13 located between the pair of inner circumferential main grooves 11 and including the tire equatorial plane CL, a second block row 14 located between the inner circumferential main groove 11 and the outer circumferential main groove 12, and a shoulder block row 15 located outboard in the tire width direction from the pair of outer circumferential main grooves 12.

The center block row 13 and the second block row 14 each have a circumferential narrow groove (circumferential groove). The circumferential narrow groove 16 extends continuously around the entire circumference of the tire while repeatedly bending in the tire width direction at the bending portion (in this example, repeatedly bending in the tire width direction at the angular bending portion, i.e., zigzag while repeatedly bending in the tire width direction at the bending portion). A plurality of inner lug grooves (lug grooves) 17 are formed in the center block row 13 and the second block row 14 at intervals in the tire circumferential direction. The inner lug grooves 17 are arranged over the entire tire width direction length of the center block row 13 and the second block row 14, and are divided in the tire width direction by the circumferential narrow groove 16. In each of the center block row 13 and the second block row 14, the inner lug grooves 17 located on one side of the circumferential narrow groove 16 in the tire width direction and the inner lug grooves 17 located on the other side of the circumferential narrow groove 16 are different from each other in the tire circumferential direction. Each of the inner lug grooves 17 opens into the circumferential narrow groove 16 and into the inner circumferential main groove 11 or the outer circumferential main groove 12.

1, in this embodiment, as described above, the inner circumferential main groove 11 and the outer circumferential main groove 12 each extend linearly along the tire circumferential direction (i.e., at an angle of 0° with respect to the tire circumferential direction) when viewed from the tread surface, but the inner circumferential main groove 11 and/or the outer circumferential main groove 12 may extend in the tire circumferential direction while repeatedly bending in the tire width direction at bending portions. That is, the inner circumferential main groove 11 and/or the outer circumferential main groove 12 may extend in a wavy manner in the tire circumferential direction.
In this specification, "wavy" or "extending in a wavy manner" refers to extending while repeatedly bending at bends, and includes both extending while repeatedly bending at rounded bends, and extending while repeatedly bending (i.e., bending) at angular bends (i.e., bends) (in this case, also referred to as "zigzag-like" or "extending in a zigzag manner").
As shown in FIG. 1, in this embodiment, as described above, the circumferential narrow groove 16 extends in the tire circumferential direction while repeatedly bending in the tire width direction at the bending portion (i.e., in a wavy shape) when viewed from the tread surface. However, the circumferential narrow groove 16 may extend in a straight line along the tire circumferential direction.

1, in this embodiment, the center block row 13 is composed of two block rows 131 and 132 in which blocks of the same configuration are lined up in the tire circumferential direction, sandwiching a circumferential narrow groove (circumferential groove) 16 in the tire width direction. The center block row 13 includes a large number of center blocks (blocks) 13a, 13b that are partitioned by an inner circumferential main groove (circumferential groove) 11, a circumferential narrow groove (circumferential groove) 16, and two inner lug grooves (lug grooves) 17 adjacent in the tire circumferential direction.
In this embodiment, each of the pair of second block rows 14 is composed of two block rows 141 and 142, or two block rows 143 and 144, in which blocks of the same configuration are lined up in the tire circumferential direction, sandwiching a circumferential narrow groove (circumferential groove) 16 in the tire width direction. Each of the pair of second block rows 14 includes a large number of second blocks (blocks) 14a, 14b, 14c, and 14d partitioned by an inner circumferential main groove (circumferential groove) 11 and a circumferential narrow groove (circumferential groove) 16, or an outer circumferential main groove (circumferential groove) 12 and a circumferential narrow groove (circumferential groove) 16, and two inner lug grooves (lug grooves) 17 adjacent in the tire circumferential direction.
That is, in the tire 1 of this embodiment, blocks defined by circumferential grooves and lug grooves are formed on the tread surface 10 .

Each of the center blocks (blocks) 13a, 13b and the second blocks (blocks) 14a to 14d has a plurality of inner sipes (sipes) 18 extending in the tire width direction. In other words, in this embodiment, at least some (in this example, all) of the blocks (13a, 13b, 14a to 14d) located in the tire width direction region sandwiched between a pair of circumferential grooves (11, 12) on the outermost side in the tire width direction, sandwiching the tire equatorial plane CL, have sipes extending in the tire width direction. In each of these blocks, a plurality of inner sipes 18 are formed at intervals in the tire circumferential direction. More specifically, each of these blocks has at least three (in this example, three) inner sipes 18 extending in the tire width direction. In addition, in each of these blocks, the inner sipes 18 open, at least on one side in the tire width direction (in this example, both sides in the tire width direction), to the inner circumferential main groove (circumferential groove) 11, the outer circumferential main groove (circumferential groove) 12, or the circumferential narrow groove (circumferential groove) 16.
That is, in this embodiment, the block has a plurality of sipes extending in the tire width direction. More specifically, in this embodiment, the block has at least three sipes extending in the tire width direction, at least one side in the tire width direction opening into the circumferential groove.

In this embodiment, the groove depth of the inner sipes 18 is shallower than the groove depth of the circumferential narrow grooves 16. In addition, the groove depth of the inner sipes 18 is, for example, 50% to 100% of the groove depth of each of the inner circumferential main groove 11 and the outer circumferential main groove 12.
In this embodiment, a plurality of inner sipes 18 are disposed in each of the center blocks 13a, 13b and the second blocks 14a to 14d, and the same number of inner sipes 18 are disposed in each of these blocks.
In this embodiment, circumferential sipes 19 extending linearly along the tire circumferential direction in a tread surface view are formed on both circumferential ends of each of the center blocks 13a, 13b and the second blocks 14a to 14d in the tire circumferential direction. However, the circumferential sipes 19 do not necessarily have to be formed on both circumferential ends of each of the center blocks 13a, 13b and the second blocks 14a to 14d in the tire circumferential direction.

As shown in FIG. 1, in this embodiment, the multiple (more specifically, at least three) inner sipes (sipes) 18 in each of the center blocks 13a, 13b and the second blocks 14a to 14d include a first sipe 18a. Also, the inner sipes 18 in each of these blocks include a second sipe 18b that has a different configuration from the first sipe 18a. That is, in this embodiment, the multiple inner sipes (sipes) 18 in each of the above blocks include a first sipe 18a and a second sipe 18b. More specifically, in this embodiment, the at least three inner sipes (sipes) 18 in each of the above blocks are composed of a first sipe 18a and a second sipe 18b.
The configuration and arrangement of the inner sipes (sipes) 18, including the first sipes 18a and the second sipes 18b, in each of the above blocks will be described in detail later with reference to FIGS.

The shoulder block row 15 has a plurality of outer lug grooves (lug grooves) 21 formed at intervals in the tire circumferential direction. The groove depth of the outer lug grooves 21 is, for example, 50% to 100% of the groove depth of the outer circumferential main groove 12. The groove width of the outer lug grooves 21 is, for example, 8.2 mm or less. The outer lug grooves 21 are arranged over the entire tire width direction length of the shoulder block row 15. At the tire width direction outer end of the tread surface 10, including the tread edge TE, a plurality of shoulder blocks (blocks) 15a, 15b are partitioned by the plurality of outer lug grooves 21 and the outer circumferential main grooves (circumferential grooves) 12.

The tire circumferential positions of the outer lug grooves 21 arranged in one shoulder block row 15 and the outer lug grooves 21 arranged in the other shoulder block row 15 are different from each other. The tire circumferential deviation amount of the outer lug grooves 21 arranged in one shoulder block row 15 and the outer lug grooves 21 arranged in the other shoulder block row 15 is equal to or less than half the tire circumferential length of the shoulder blocks 15a, 15b.
The positions in the tire circumferential direction of the outer lug grooves 21 arranged in one shoulder block row 15 and the outer lug grooves 21 arranged in the other shoulder block row 15 may be set to be equal to each other.

In this embodiment, the shoulder blocks 15a, 15b are formed with a lateral groove 22 that is narrower than the outer lug groove 21 and extends over the entire length of the shoulder blocks 15a, 15b in the tire width direction, and a longitudinal groove 23 that is narrower than the outer circumferential main groove 12 and extends over the entire length of the shoulder blocks 15a, 15b in the tire circumferential direction. Both ends of the lateral groove 22 in the tire width direction open in the tire width direction, and the inner ends of the lateral groove 22 in the tire width direction open to the outer circumferential main groove 12. Both ends of the longitudinal groove 23 in the tire circumferential direction open to the outer lug groove 21. The lateral groove 22 is disposed in the center of the shoulder blocks 15a, 15b in the tire circumferential direction, and the longitudinal groove 23 is disposed in the center of the shoulder blocks 15a, 15b in the tire width direction. The longitudinal groove 23 has a groove width equal to the groove width of the lateral groove 22.
The groove widths of the lateral groove 22 and the vertical groove 23 may be different from each other, for example, the groove width of the vertical groove 23 may be wider than the groove width of the lateral groove 22. Furthermore, the groove widths of the lateral groove 22 and the vertical groove 23 may each change midway along their respective extension directions.

The groove depth of the lateral grooves 22 is, for example, greater than 45% and less than 100% of the groove depth of the outer circumferential main groove 12. By having the groove depth of the lateral grooves 22 greater than 45% of the groove depth of the outer circumferential main groove 12, it becomes easier to individually deform the shoulder blocks 15a, 15b on both sides of the lateral groove 22 in the tire circumferential direction, and by having the groove depth be less than 100%, it is possible to suppress a decrease in the rigidity of the shoulder blocks 15a, 15b. The groove depth of the lateral grooves 22 is the same as the groove depth of the outer lug grooves 21 (for example, about 12 mm).

At least a portion of the longitudinal groove 23 is shallower than the lateral groove 22. The longitudinal groove 23 has a groove depth, excluding the central portion in the tire circumferential direction and extending over more than half of the tire circumferential length, that is shallower than the lateral groove 22, for example, about 2 mm.

As shown in FIG. 1, each of the shoulder blocks 15a and 15b has a rectangular shape with one pair of sides extending in the tire width direction and the remaining pair of sides extending in the tire circumferential direction when viewed from the tread surface. Of the four corners of each of the shoulder blocks 15a and 15b, chamfered portions are formed at the two corners located on the outer side in the tire width direction. The chamfered portions are located in positions in the shoulder blocks 15a and 15b away from the lateral grooves 22 and the longitudinal grooves 23.

In each of the shoulder blocks 15a, 15b, an outer sipe (sipe) 24 extending in the tire width direction is formed in the tire width direction inner part located on the tire width direction inner side of the longitudinal groove 23. The outer sipes 24 extend linearly in the tire width direction when viewed from the tread surface, and a plurality of outer sipes are formed in each of the shoulder blocks 15a, 15b at intervals in the tire circumferential direction. The outer sipes 24 are arranged in the same number (one in this example) in each part located on both sides of the lateral groove 22 in the tire circumferential direction in the tire width direction inner part of the shoulder blocks 15a, 15b. The outer sipes 24 are arranged in the tire circumferential center part of the part located between the tire circumferential edge of the shoulder blocks 15a, 15b and the lateral groove 22 in the tire width direction inner part of the shoulder blocks 15a, 15b.

The inner end of the outer sipe 24 in the tire width direction opens into the outer circumferential main groove 12. The outer end of the outer sipe 24 in the tire width direction is located outward in the tire width direction from the inner edge of the shoulder blocks 15a, 15b in the tire width direction by, for example, less than one-quarter of the tire width direction length of the shoulder blocks 15a, 15b.

Next, the configuration and arrangement of the inner sipes (sipes) 18, including the first sipes 18a and the second sipes 18b, in the center blocks 13a, 13b and the second blocks 14a to 14d will be described with reference to Figures 2 to 4.

Figure 2 is an enlarged plan view for explaining an example of a block in the tire of Figure 1. Figure 3A is an enlarged plan view for explaining a first sipe in the tire of Figure 1, Figure 3B is an X1-X1 cross-sectional view of Figures 2 and 3A, and Figure 3C is an X2-X2 cross-sectional view of Figure 2. Figure 4 is a schematic plan view for explaining the relationship between the protrusion direction of the projection from the sipe wall of the first sipe and the projection direction of the ridge of the second sipe.

FIG. 2 shows an enlarged view of an example of a block in the tire 1 of the present embodiment shown in FIG. 1, more specifically, a configuration of the second block 14b shown in FIG.
The following description will mainly focus on the second block 14b as an example. In this embodiment, the configurations of the center blocks 13a, 13b and the second blocks 14a, 14c, 14d shown in FIG. 1 and the inner sipes 18 (first sipes 18a, second sipes 18b) included in each block are substantially the same, except for the fact that the contour shape of each block on the tread surface 10, the inclination angle of the inner sipes 18 (first sipes 18a, second sipes 18b) relative to the tire width direction, the protrusion direction PJD of the protrusions 18ap of the first sipes 18a from the sipe wall, and the projection direction SUD of the peaks 18bm of the second sipes 18b, which will be described later, may differ between the blocks as shown in FIG. 1.

1 and 2, in this embodiment, the second block (block) 14b has a plurality of inner sipes (sipes) 18 extending in the tire width direction. In this example, the second block 14b has at least three (more specifically, three in this example) inner sipes 18 extending in the tire width direction.
The plurality of inner sipes 18 include a first sipe 18a. In this example, the at least three inner sipes 18 are composed of a first sipe 18a and a second sipe 18b.

As shown in Figs. 1 and 2, in this embodiment, only one first sipe 18a is formed at approximately the center of the second block 14b in the tire circumferential direction.
However, the first sipe 18a does not have to be formed at approximately the center of the second block 14b in the tire circumferential direction, and may be formed at a position in the tire circumferential direction shifted from the approximately center. Also, the second block 14b may have a plurality of first sipes 18a, for example, two or two to three. However, from the viewpoint of rigidity balance and the like, it is preferable that only one first sipe 18a is formed at approximately the center of the second block 14b in the tire circumferential direction.

As shown in Figs. 1 and 2, in this embodiment, the first sipe 18a extends linearly when viewed from the tread surface.
Moreover, the first sipe 18a has both sides in the tire width direction that open into the circumferential groove (the inner circumferential main groove 11 or the circumferential narrow groove 16). More specifically, the first sipe 18a has an end on one side in the tire width direction (the left side in Figs. 1 and 2) that opens into the circumferential narrow groove 16, and an end on the other side in the tire width direction (the right side in Figs. 1 and 2) that opens into the inner circumferential main groove 11, and between these ends, the first sipe 18a extends continuously in the tire width direction across the second block 14b in the tire width direction.
However, it is sufficient that at least one side in the tire width direction of the first sipe 18a opens into the inner circumferential main groove 11 or the circumferential narrow groove 16, and for example, one side in the tire width direction may open into the circumferential narrow groove 16 and the other side in the tire width direction may terminate within the second block 14b, or the other side in the tire width direction may open into the inner circumferential main groove 11 and one side in the tire width direction may terminate within the second block 14b. However, from the viewpoint of ensuring sufficient water absorption performance (and thus ice and snow performance), it is preferable that the first sipe 18a opens into the circumferential groove (the inner circumferential main groove 11 or the circumferential narrow groove 16) on both sides in the tire width direction.

As shown in FIGS. 3A and 3B, in this embodiment, the first sipe 18a is a protruding sipe having a protrusion 18ap that protrudes from a sipe wall on one side of the first sipe 18a and extends in the sipe depth direction.
Because the first sipe 18a is a protruding sipe having protrusions 18ap with a predetermined configuration, it is possible to sufficiently prevent the sipe from closing due to load application, making it impossible to obtain a sufficient water absorption effect, even though the sipes are provided with the intention of achieving a water absorption effect through the sipes.

As shown in FIG. 3B, the protrusion 18ap in the first sipe 18a has a length Dp (hereinafter also referred to as the "depth" of the protrusion) that is 1/2 or more of the sipe depth Ds (i.e., the entire sipe depth of the first sipe 18a) in the sipe depth direction. In this example, the depth Dp of the protrusion 18ap is, for example, about 3/5 of the sipe depth Ds. Since the depth Dp of the protrusion 18ap is 1/2 or more of the sipe depth Ds, the sipe can be sufficiently prevented from closing (and thus the water absorption performance can be reduced), and the sipe closure suppression effect can be maintained even after wear has progressed. Furthermore, the sipe walls can easily support each other, which can improve block rigidity and contribute to improving wear resistance.
From the same viewpoint, it is preferable that the protrusion 18ap of the first sipe 18a has a length (depth) Dp that is 3/4 or more of the sipe depth Dl (see FIG. 3B) excluding the widened portion 18ab described later in the sipe depth direction (i.e., the sipe depth of the portion of the first sipe 18a excluding the widened portion 18ab). In this example, the depth Dp of the protrusion 18ap is, for example, about 7/8 of the sipe depth Dl excluding the widened portion 18ab.

However, the depth Dp of the projection 18ap is preferably 4/5 or less of the sipe depth Ds.
In this case, it becomes easier to eliminate the problem that the thin blade used as a mold for forming sipes during tire manufacturing becomes difficult to remove, which can lead to damage to the blade or rubber, and it also eliminates the problem that the volume of the sipes is reduced, which could conversely reduce the water absorption performance of the sipes.
The depth Dp of the protrusion 18ap may be, for example, about 7 mm.

As shown in FIG. 3B, the protrusion 18ap of the first sipe 18a extends from the tread surface 10 in the sipe depth direction.
Because the protrusions 18ap extend from the tread surface 10 in the sipe depth direction, the protrusions support the space between the sipe walls from the early stages of wear, preventing the sipes from closing and sufficiently suppressing the deterioration of water absorption performance. In particular, in heavy-duty tires, the sipes are most likely to close near the tread surface 10, so the deterioration of water absorption performance can be more effectively suppressed.

Furthermore, as shown in FIG. 3B, the protrusion 18ap of the first sipe 18a has a tapered shape in which the width in the sipe width direction decreases toward the sipe bottom at the lower end on the sipe bottom side in a cross-sectional view in the sipe depth direction.
In this case, it becomes easier to eliminate the problem that it becomes difficult to remove the thin blade used as a mold for forming sipes during tire manufacturing, which can easily lead to damage to the blade or rubber.

From the above, the first sipe 18a is a protruding sipe having a protrusion 18ap protruding from the sipe wall on one side of the first sipe 18a and extending in the sipe depth direction, and the protrusion 18ap on the first sipe 18a has a length in the sipe depth direction that is at least half the sipe depth Ds and extends from the tread surface 10 in the sipe depth direction, which satisfactorily suppresses the decrease in water absorption performance caused by the sipes closing.

As shown in FIG. 3B, in this embodiment, the first sipe 18a is a flask sipe that has a flask shape having an expanded portion 18ab on the sipe bottom side in a cross-sectional view in the sipe depth direction.
By making the first sipes 18a into flask sipes as described above, the volume of the sipes can be sufficiently secured, and the deterioration of water absorption and drainage performance caused by providing the protrusions 18ap on the first sipes 18a can be further suppressed.

As shown in FIG. 3B, in this embodiment, the first sipe 18a has a linear portion 18as that extends perpendicularly from the tread surface 10 in a cross-sectional view in the sipe depth direction.
More specifically, as shown in FIG. 3B , in this example, the first sipe 18a, which is a flask sipe, has, in a cross-sectional view in the sipe depth direction, a straight portion 18as in which both sipe walls extend linearly in the sipe depth direction perpendicular to the tread surface 10 with the same sipe width, and an expanded portion 18ab that is connected to the straight portion 18as and extends toward the sipe bottom while gradually increasing the sipe width as it approaches the sipe bottom.
The sipe width Wsb of the widened portion 18ab where the sipe width of the first sipe 18a is maximum is preferably, for example, 1.5 to 4.0 times the sipe width Ws (i.e., in this example, the sipe width of the linear portion 18as) on the tread surface 10. The sipe width Ws of the first sipe 18a can be, for example, 0.3 to 1.5 mm.
Moreover, the sipe depth Dl of the first sipe 18a excluding the widened portion 18ab (in this example, the sipe depth of the linear portion 18as) is preferably, for example, 0.6 to 0.8 times the sipe depth Ds of the first sipe 18a. The sipe depth Ds of the first sipe 18a may be, for example, 8 to 15 mm.

As shown in FIG. 3A, in this embodiment, the first sipe 18a has a plurality of protrusions 18ap provided thereon at intervals in the sipe longitudinal direction of the first sipe 18a as viewed from the tread surface.
In this case, for example, compared to a case in which only one protrusion 18ap with a relatively long length in the longitudinal direction of the first sipe 18a is provided near the center of the longitudinal direction of the sipe, it is possible to more effectively suppress deterioration in water absorption performance by ensuring sufficient sipe volume while ensuring sufficient block rigidity.
However, only one protrusion 18ap may be provided on the first sipe 18a.
In this example, two protrusions 18ap are provided on the first sipe 18a as shown in Fig. 3A. However, three or more protrusions 18ap may be provided on the first sipe 18a.

As shown in FIG. 3A, in this embodiment, the protrusions 18ap of the first sipes 18a are not provided at the ends of the first sipes in the sipe longitudinal direction when viewed from the tread surface.
In this case, a protrusion of small volume can sufficiently prevent the sipe from closing, thereby effectively preventing a decrease in water absorption performance, and also prevents damage to the blade used to form the sipe, thereby reducing manufacturing problems.

Also, as shown in Figures 3A and 3B, the protrusion 18ap in the first sipe 18a has a length Hp (hereinafter also referred to as the "height" of the protrusion) that is greater than or equal to 3/5 of the sipe width Ws in the sipe width direction when viewed from the tread surface.
In this case, the sipes can be reliably prevented from closing when a heavy load is applied, and the deterioration of water absorption performance can be more effectively suppressed.

However, as shown in Figures 3A and 3B, it is preferable that the height Hp of the protrusion 18ap is smaller than the sipe width Ws (i.e., a gap SP is formed between the tip of the protrusion 18ap in the protruding direction and the sipe wall opposite the tip), and it is more preferable that the height Hp is 9/10 or less of the sipe width Ws.
In these cases, damage to the blades used to form the sipes can be suppressed, and the deterioration of snow and ice performance caused by the prevention of snow that has entered the sipes being prevented from being discharged can be suppressed.
The height Hp of the projection 18ap may be, for example, about 0.6 mm.

As shown in Fig. 3A, the protrusion 18ap of the first sipe 18a has a tapered shape in which the length in the sipe longitudinal direction (hereinafter also referred to as the "length" of the protrusion) in the tread surface view becomes shorter toward the tip side of the protrusion 18ap. That is, in this embodiment, the protrusion 18ap has a tapered shape in which the sipe longitudinal length Lpt at the tip is shorter than the sipe longitudinal length Lp at the base end, and the length gradually becomes shorter linearly from the base end side toward the tip side. More specifically, in the example of Fig. 3A, the protrusion 18ap has a trapezoidal shape with the base end side as the lower base and the tip end side as the upper base.
In this case, the projections are less likely to be crushed in the sipe width direction, and the deterioration of water absorption performance can be more effectively suppressed.

In this embodiment, from the viewpoint of maintaining an appropriate rigidity balance, the first sipe 18a has the same sipe longitudinal length La between one end of the first sipe 18a in the sipe longitudinal direction and the protrusion 18ap, the same sipe longitudinal length Lp at the base end of the protrusion 18ap, and the same sipe longitudinal length Lb (see FIG. 3A) between two protrusions 18ap adjacent in the sipe longitudinal direction. However, the sipe longitudinal lengths La, Lp, and Lb do not have to be the same.
The sipe longitudinal length Ls (see FIG. 3A) of the first sipe 18a may be, for example, about 20 mm. The sipe longitudinal lengths La, Lp, and Lb may be, for example, about 4 mm. The sipe longitudinal length Lpt of the tip of the projection 18ap may be, for example, about 2 mm.

Here, in this embodiment, as described above, the first sipe (sipe) 18a extends linearly when viewed from the tread surface, and is a flask sipe that has a linear portion 18as extending vertically from the tread surface 10 when viewed in a cross section in the sipe depth direction and has a flask-like shape with an expanded portion 18ab on the sipe bottom side when viewed in a cross section in the sipe depth direction. That is, the first sipe 18a is a linear vertical flask sipe.
On the other hand, in this embodiment, as shown in Figs. 1 and 2, the second sipe (sipe) 18b extends in a wavy manner with the number of peaks 18bm (18bm1, 18bm2) being three or more on at least one side in the tread tread view. Here, the "peak" in the second sipe 18b refers to a portion of the second sipe 18b in the tread tread view that protrudes from the center line 18bc of the second sipe 18b to either side in the sipe width direction (and thus in the tire circumferential direction). That is, the second sipe 18b has three or more peaks 18bmn (18bm1 or 18bm2) on at least one side (both sides in this example) between one side (upper side in Fig. 2) and the other side (lower side in Fig. 2) of the center line 18bc. In addition, the "center line" of the sipe refers to a line connecting the centers of the amplitude of the waves in the case of a wavy sipe that extends in a wavy manner in the tread tread view.
3C, the second sipe 18b is a flask sipe having a flask-like shape with an expanded portion 18bb on the sipe bottom side in a cross-sectional view in the sipe depth direction. That is, the second sipe 18b is a wavy flask sipe.
By making the first sipe 18a the linear vertical flask sipe as described above and the second sipe 18b the wavy flask sipe as described above, it is possible to sufficiently improve the snow and ice performance while ensuring the wear resistance. That is, the snow and ice performance and the wear resistance performance are excellent because the sipe walls sufficiently support each other in the snow and ice sipes that extend in a wave shape on the tread surface, but the snow and ice performance may be superior in the case of the straight sipes that extend in a straight line on the tread surface. This is because the straight sipes have an edge effect from the early stage of deformation because the block parts are easily collapsed between the sipes and pressure is easily applied to the edge components, so that the snow and ice performance (water removal and scratching effect) is superior to the snow and ice performance (water removal and scratching effect) at low input (small deformation) compared to the snow and ice performance ... straight sipes because the tread surface of the straight sipes is not uneven, and the discharge of snow that has entered the sipes and the water absorption performance are high, and the block surface is constantly refreshed, and the road surface robustness is high. In addition, by having at least three or more peaks on each side in the wavy sipe, more sufficient snow and ice performance and wear resistance can be obtained. Furthermore, since both the first sipe 18a and the second sipe 18b are flask sipes having widened portions (18ab, 18bb) on the sipe bottom side, more sufficient water absorption and drainage performance is ensured. For the above reasons, by having the first sipe 18a, which is the linear vertical flask sipe as described above, in addition to the second sipe 18b, which is the wavy flask sipe as described above, the wear resistance of the tire can be ensured while the snow and ice performance can be sufficiently improved.

In this example, as shown in FIG. 1 and FIG. 2, the second sipe 18b has four peaks 18bm1 on one side (upper side in FIG. 2) of the sipe width direction across the center line 18bc, and three peaks 18bm2 on the other side (lower side in FIG. 2), but it may be the other way around (three on one side and four on the other side). Also, the number of peaks 18bm in the second sipe 18b may be, for example, three on one side (upper side in FIG. 2) of the sipe width direction and two on the other side (lower side in FIG. 2), or it may be the other way around (two on one side and three on the other side). Also, the number of peaks 18bm may be, for example, three on each side in the sipe width direction. Furthermore, the number of peaks 18bm may be, for example, four or more on each side in the sipe width direction. In addition, from the viewpoint of ensuring that the direction of projection SUD of the ridges 18bm (described later) is determined to one side in the tire circumferential direction, it is preferable that the number of ridges 18bm in the second sipe 18b is not the same on both sides in the sipe width direction.

As described above, as shown in FIG. 3C, the second sipe 18b has a widened portion 18bb on the sipe bottom side. In this example, the second sipe 18b has a 3D portion that not only extends wavy in the tread tread view (i.e., on the tread tread 10) but also extends wavy in the sipe depth direction in the sipe depth direction region from the tread tread 10 to the widened portion 18bb. In FIG. 3C, the configuration of the sipe depth direction region of the second sipe 18b from the tread tread 10 to the widened portion 18bb, including the 3D portion, is illustrated in a schematic manner. Since the second sipe 18b includes a 3D portion, the sipe walls support each other more reliably, so that the block rigidity is more sufficiently ensured, the lifting of the block surface at the time of input is suppressed, the ground contact area is improved, and the sipe volume is sufficiently ensured to improve the water absorption performance, which further improves the snow and ice performance, and the wear resistance is also further improved by ensuring the block rigidity more sufficiently.
However, the second sipe 18b does not have to include a 3D portion, and may be composed of a straight portion and a widened portion, similar to the first sipe 18a illustrated in FIG. 3B.

The sipe width Wsb of the widened portion 18bb where the second sipe 18b has a maximum sipe width is preferably, for example, 1.5 to 4.0 times the sipe width Ws at the tread surface 10. The sipe width Ws of the second sipe 18b may be, for example, 0.3 to 1.0 mm.
The sipe depth Dl (see FIG. 3C) of the second sipe 18b excluding the widened portion 18bb is preferably, for example, 0.7 to 0.9 times the sipe depth Ds of the second sipe 18b. The sipe depth Ds of the second sipe 18b may be, for example, 8 to 15 mm.

3B and 3C, in this embodiment, the sipe width Ws of the first sipe 18a on the tread surface 10 is the same as the sipe width Ws of the second sipe 18b on the tread surface 10. In this embodiment, the sipe width Wsb of the widened portion 18ab where the sipe width of the first sipe 18a is maximum is the same as the sipe width Wsb of the widened portion 18bb where the sipe width of the second sipe 18b is maximum.
In this case, the sipe widths Ws, Wsb can be adjusted so that sufficient snow and ice performance is obtained from both the first sipes 18a and the second sipes 18b.

3B and 3C, in this embodiment, the sipe depth Ds of the first sipes 18a and the sipe depth Ds of the second sipes 18b are the same as each other.
In this case, the sipe depth Ds can be adjusted so that sufficient snow and ice performance is obtained from both the first sipes 18a and the second sipes 18b.

3B and 3C, in the present embodiment, in a cross-sectional view in the sipe depth direction, the size (area) of the widened portion 18ab of the first sipe 18a is made larger than the size (area) of the widened portion 18bb of the second sipe 18b. That is, in this example, the sipe widths Wsb of the widened portions shown in the figures are the same for the first sipe 18a and the second sipe 18b, but the sipe depth direction length (corresponding to Ds-Dl in the figures) of the widened portions is longer for the first sipe 18a.
In this case, by ensuring sufficient volume for the first sipes 18a, the water absorption and drainage performance, and therefore the ice and snow performance, of the first sipes 18a can be more effectively improved, and the sipe walls of the second sipes 18b can support each other more firmly, thereby effectively improving the wear resistance performance of the second sipes 18b in particular.

Next, referring again to Figures 1 and 2, the preferred arrangement of the first sipes 18a and second sipes 18b on the tread surface 10, which is also used in this embodiment, will be described.

As described above, the second block 14b shown in Fig. 2, which is an example of a block, has at least three sipes extending in the tire width direction, at least one side in the tire width direction opening into the circumferential groove, and the at least three sipes are composed of the first sipes 18a and the second sipes 18b as described above. Here, in this embodiment, of the at least three sipes in the second block (block) 14b, only the sipe on the center side in the tire circumferential direction in the block is the first sipe 18a. In other words, in the block, the second sipes 18b are arranged on both sides of the first sipe 18a in the tire circumferential direction, and none of the first sipes 18a are arranged at the end side in the tire circumferential direction.
In this case, the water absorption performance and thus the ice and snow performance can be effectively improved, and the variation in the water absorption performance and thus the ice and snow performance due to the difference in the mounting direction of the tire on the vehicle can be avoided. During tire rotation, the ground contact surface is more likely to change from ice to water on the trailing edge of the same block, but by arranging wavy sipes with a larger sipe volume and higher water absorption performance on both ends in the tire circumferential direction than the straight sipes, water can be absorbed more effectively regardless of the mounting direction. In addition, in this case, block deformation can be suppressed and thus the wear resistance can be effectively improved, and the variation in block deformation and thus the wear resistance performance due to the difference in the mounting direction of the tire on the vehicle can be avoided. During tire rotation, the block deformation amount is larger on the trailing edge of the same block, but by arranging wavy sipes with a higher shear stiffness on both ends in the tire circumferential direction than the straight sipes, block deformation can be suppressed more effectively regardless of the mounting direction. In other words, the above-mentioned configuration can improve water absorption performance, snow and ice performance, block deformation, and wear resistance, while suppressing variations in snow and ice performance and wear resistance caused by differences in the mounting direction of the tire on the vehicle during use. Therefore, the above-mentioned configuration is particularly effective when applied to heavy-duty tires such as truck and bus tires, which are not usually specified in the mounting direction.

From a similar viewpoint, as in the present embodiment shown in Figures 1 and 2, it is preferable that, of the at least three sipes in a second block (block) 14b, only one sipe on the central side in the tire circumferential direction within that block is a first sipe 18a.
In this case, as in the present embodiment, for example, by arranging one second sipe 18b on each side of the first sipe 18a in the circumferential direction of the tire, it is possible to suppress variations in ice and snow performance and wear resistance due to differences in the mounting direction of the tire on the vehicle when in use, and it is possible to achieve a better balance between ice and snow performance and wear resistance.

As shown in FIG. 2, in this embodiment, on the tread surface 10, the average distance in the tire circumferential direction between the first sipe 18a and the second sipe 18b is shorter than the average distance in the tire circumferential direction between the second sipe 18b and the tire circumferential edge 14be of the second block (block) 14b.
In this case, the wear resistance can be further improved, and the variation in wear resistance due to the difference in the mounting direction on the vehicle during use can be further suppressed. During tire rotation, the block deformation amount is larger on the trailing edge side within the same block, but by making the tire circumferential length of the block portion between the second sipe 18b and the tire circumferential edge of the block, i.e., on both ends in the tire circumferential direction, longer than between the first sipe 18a and the second sipe 18b, i.e., on the tire circumferential center side, block deformation can be more effectively suppressed regardless of the mounting direction.
The "average distance in the tire circumferential direction" is measured with respect to the sipes (first sipe 18a, second sipe 18b) based on the sipe center lines 18ac, 18bc on the tread surface 10, and the "average distance" is calculated as (maximum distance + minimum distance)/2. When a plurality of first sipes 18a or second sipes 18b are formed in the same block, the average distance in the tire circumferential direction is measured based on the first sipe 18a that is closest to the center in the tire circumferential direction in that block and the second sipe 18b that is closest to the edge in the tire circumferential direction in that block.

As shown in FIG. 1, in this embodiment, the first sipes 18a and the second sipes 18b are provided in a plurality of blocks adjacent to each other in the tire width direction (in this example, the second blocks 14a, 14b, the center blocks 13a, 13b, and the second blocks 14c, 14d. Hereinafter, the "center blocks" and the "second blocks" may be simply referred to as "blocks"), and between two blocks adjacent to each other in the tire width direction (in this example, the blocks 14a and 14b, the blocks 14b and 13a, the blocks 13a and 13b, the blocks 13b and 14c, and the blocks 14c and 14d), the deflection directions SUD (see FIG. 4) of the peaks 18bm of the second sipes 18b are on the opposite sides in the tire circumferential direction. Note that, in the same block, the deflection directions SUD of the peaks 18bm of the second sipes 18b are on the same side in the tire circumferential direction at both ends of the second sipe 18b in the tire width direction.
In this case, the variation in snow and ice performance caused by the difference in the mounting direction on the vehicle when the tire is used can be suppressed. More specifically, the second sipe 18b, which is a wavy sipe, has a higher edge effect of biting snow and ice with the sipe edge on the side with more peaks 18bm in the tire circumferential direction, so that the side with more peaks 18bm in the tire circumferential direction, i.e., the side with the projection direction SUD of the peaks 18bm, is set as the leading side during tire rotation, and the snow and ice performance tends to be higher than the trailing side during tire rotation. In other words, the projection direction SUD of the peaks 18bm on which there are many peaks 18bm has a directional property with respect to snow and ice performance. Therefore, by reversing the projection direction SUD of the peaks 18bm in the second sipe 18b between blocks adjacent in the tire width direction, the variation in snow and ice performance caused by the difference in the mounting direction on the vehicle when the tire is used can be suppressed.

Here, the direction of projection SUD of the peak 18bm of the second sipe 18b, which is a wavy sipe, refers to the direction in which the peak 18bm first protrudes as the second sipe 18b extends from the end of one or the other side in the tire width direction toward the inside of the block, as shown by the white arrow in Fig. 4. For example, in the example shown in Fig. 4, the peak bm1 (bm) of each of the two second sipes 18b first protrudes toward one side in the tire circumferential direction as the second sipes 18b extend from the end of the tire width direction toward the inside of the block, so that the directions of projection SUD of the peaks 18bm are all obliquely upward on the paper, that is, all on the same one side in the tire circumferential direction. Note that Fig. 4 is a schematic plan view for explaining the relationship between the protruding direction PJD of the projection 18ap of the first sipe 18a from the sipe wall, which will be described later, and the direction of projection SUD of the peak 18bm of the second sipe 18b, and as an example, the state of the second block 14b in the example of Fig. 2 is shown in schematic form.
2 and 4, in the present embodiment, the projection directions of the peaks 18bm of the second sipes 18b are all the same in one block (block 14b in this example), which allows the shapes of the multiple small blocks partitioned by the sipes in one block to be substantially the same, and allows the deformation tendency to be the same, thereby suppressing uneven wear.

Furthermore, as shown in FIG. 4, in this embodiment, the protrusion direction PJD of the above-mentioned protrusion 18ap of the first sipe 18a from the sipe wall (hereinafter, simply referred to as the "protrusion direction (PJD) of the protrusion (18ap)" and shown by a thick black arrow in FIG. 4) is the opposite side in the tire circumferential direction to the projection direction of the peak 18bm of the second sipe 18b. In other words, the protrusion 18ap of the first sipe 18a protrudes from the sipe wall on one side of the first sipe 18a (the upper side of the paper in FIG. 4) on the opposite side in the tire circumferential direction to the projection direction SUD of the peak 18bm of the second sipe 18b. In further other words, the protrusion 18ap of the first sipe 18a protrudes from the sipe wall on the projection direction SUD side of the peak 18bm of the second sipe 18b.
In this case, the variation in snow and ice performance due to the difference in the mounting direction of the tire on the vehicle during use can also be suppressed. More specifically, as described above, the second sipe 18b, which is a wavy sipe, tends to have higher snow and ice performance when the side of the ridge 18bm in the swing-out direction SUD is set as the step-in side during tire rotation than when the side of the ridge 18bm in the kick-out side during tire rotation. Similarly, the first sipe 18a, which is a straight sipe, has higher snow and ice performance on the sipe wall side where the protrusion 18ap does not protrude, i.e., the side of the protrusion 18ap in the protruding direction PJD from the sipe wall, so that the snow and ice performance tends to be higher when the side of the protrusion PJD is set as the step-in side during tire rotation than when the side of the protrusion PJD is set as the kick-out side during tire rotation. That is, the swing-out direction SUD of the ridge 18bm and the protrusion direction OJD of the protrusion 18ap have the same directionality with respect to snow and ice performance. Therefore, within the same block, the protruding direction PJD of the protrusion 18ap in the first sipe 18a is on the opposite side of the tire circumferential direction to the projection direction SUD of the ridge 18bm in the second sipe 18b, thereby suppressing variations in ice and snow performance due to differences in the mounting direction of the tire on the vehicle when in use.

As in the case of the projection direction SUD of the ridge 18bm of the second sipe 18b described above, in this embodiment, although not shown, the first sipe 18a and the second sipe 18b are provided in a plurality of blocks adjacent to each other in the tire width direction (in this example, blocks 14a, 14b, 13a, 13b, 14c, and 14d), and between two blocks adjacent to each other in the tire width direction (in this example, blocks 14a and 14b, blocks 14b and 13a, blocks 13a and 13b, blocks 13b and 14c, and blocks 14c and 14d), the protrusion directions PJD of the protrusions 18ap in the first sipe 18a from the sipe wall are on opposite sides in the tire circumferential direction.
As in the case of the deflection direction SUD of the ridges 18bm of the second sipes 18b described above, this case also suppresses variation in snow and ice performance due to differences in the mounting direction of the tire on the vehicle when in use. This is because, as in the case of the deflection direction SUD of the ridges 18bm, the protrusion direction OJD of the protrusions 18ap also has directional properties with respect to snow and ice performance.

As shown in Fig. 1, in the present embodiment, in the tread surface view, two adjacent blocks via a circumferential narrow groove (circumferential groove) 16 overlap each other in the tire width direction in a part in the tire circumferential direction. More specifically, for example, two block rows 141 and 142 constituting the second block row 14 on one side in the tire width direction in Fig. 1 are arranged such that the blocks 14a and 14b of the blocks 14a and 14b overlap each other in the tire width direction only in a part of the tire circumferential direction, not in the entire tire circumferential region of the blocks 14a and 14b. In other words, the two block rows 141 and the brick row 142 adjacent in the tire width direction via the circumferential narrow groove 16 that extends while bending in the tire circumferential direction are arranged in the tire circumferential direction such that the blocks 14a and 14b constituting each row are staggered in the tire width direction.
In this case, variations in snow and ice performance and wear resistance due to differences in circumferential position of the tire are suppressed, and the characteristics tend to be uniform in the circumferential direction of the tire.
1, the same applies to blocks 13a and 13b of block rows 131 and 132 constituting the center block row 13, and blocks 14c and 14d of block rows 143 and 144 constituting the second block row 14 on the other side in the tire width direction. Furthermore, the same applies to two blocks adjacent to each other via the inner circumferential main groove (circumferential groove) 11 or the outer circumferential main groove (circumferential groove) 12 (blocks 15a and 14a, blocks 14b and 13a, blocks 13b and 14c, and blocks 14d and 15b).

1, in this embodiment, the first sipes 18a and/or the second sipes 18b are formed in a plurality of blocks 14a, 14b, 13a, 13b, 14c, and/or 14d arranged at different positions in the tire width direction. In addition, in a tread surface view, the first sipes 18a and/or the second sipes 18b are inclined with respect to the tire circumferential direction, and the inclination angle of the first sipes 18a and/or the second sipes 18b with respect to the tire width direction is smaller for the blocks 13a and/or 13b on the inner side in the tire width direction than for the blocks 14a, 14b, 14c, and/or 14d on the outer side in the tire width direction. More specifically, in this example, the inclination angle of the first sipes 18a and the second sipes 18b in the center blocks 13a and 13b with respect to the tire width direction is, for example, less than 5°, more specifically, for example, 0°, and the inclination angle of the first sipes 18a and the second sipes 18b in the second blocks 14a, 14b, 14c, and 14d with respect to the tire width direction is, for example, 5 to 25°, more specifically, for example, 10°. Note that the inclination angle of the sipe with respect to the tire width direction is measured based on the sipe center lines 18ac and 18bc shown in FIG. 2.
According to the above configuration, the extension direction of each sipe on the tread surface is close to the kick line of the ground contact shape at low load such as an empty state, so that the edge effect of each sipe is enhanced and the snow and ice performance can be further improved. Also, according to the above configuration, in the tire width direction region near the tire equatorial plane CL where the ground contact pressure is the highest, the inclination angle of the sipe with respect to the tire width direction is close to 0° so that the sipe edges are sufficiently effective in the tire circumferential direction, so that the braking and driving forces in the tire circumferential direction, especially when traveling straight, can be increased, and in other tire width direction regions, the angle of the sipe with respect to the tire width direction is relatively larger than near 0° so that the sipe edges are effective not only in the tire circumferential direction but also in the tire width direction, so that the lateral force during cornering, and therefore the braking and driving forces can also be increased.

The above describes exemplary embodiments of the present invention, and various modifications can be made without departing from the scope of the claims.
For example, in the tire 1 in the above-described embodiment, the first sipes 18a and the second sipes 18b (and thus the first sipes 18a) are formed in all of the block rows 131, 132, 141-144 arranged in the tire width direction region between the circumferential grooves on the outermost sides in the tire width direction in each tire half portion sandwiching the tire equatorial plane CL, and furthermore, in all of the blocks 13a, 13b, 14a-14d in the tire width direction region, but the first sipes 18a and the second sipes 18b (and thus the first sipes 18a) may be formed only in some of these blocks. For example, the first sipes 18a and the second sipes 18b (and thus the first sipes 18a) may be formed only in the blocks of at least one of the block rows among the above-described block rows.

The tire according to the present invention can be used as any type of tire, for example, as a passenger car tire, a truck/bus tire, or a construction/mining vehicle tire, and is particularly suitable for use as a heavy-duty tire such as a truck/bus tire or a construction/mining vehicle tire, and particularly as a truck/bus tire.

Contributing to the United Nations-led Sustainable Development Goals (SDGs)

The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is considered to be a technology that can contribute to "No. 12 - Responsible consumption and production" and "No. 13 - Concrete measures against climate change."

1: tire, 10: tread surface, 11: inner circumferential main groove (circumferential groove), 12: outer circumferential main groove (circumferential groove), 13: center block row, 13a, 13b: center block (block), 131, 132: block row, 14: second block row, 14a to 14d: second block (block), 14be: tire circumferential edge of block, 141 to 144: block row, 15: shoulder block row, 15a, 15b: shoulder block (block), 16: circumferential narrow groove (circumferential groove), 17: inner lug groove (lug groove), 18: inner sipe (sipe), 18a: first sipe (sipe), 18ab: widened portion, 18ac: sipe center line, 18ap: protrusion, 18as: straight portion, 18b: second sipe (sipe), 18bb: widened portion, 18bc: sipe center line, 18bm, 18bm1, 18bm2: ridge, 19: circumferential sipe, 21: outer lug groove (lug groove), 22: lateral groove, 23: longitudinal groove, 24: outer sipe (sipe),
CD: tire circumferential direction, CL: tire equatorial plane, Dl, Ds: sipe depth, Dp: protrusion depth, Hp: protrusion height, La, Lb, Lp, Lpt, Ls: sipe longitudinal length, PJD: protrusion protrusion direction, SLD: sipe longitudinal direction, SP: gap, SUD: ridge direction, SWD: sipe width direction, TE: tread edge, WD: tire width direction, Ws, Wsb: sipe width

Claims (7)

A tire having blocks defined by circumferential grooves and lug grooves formed on a tread surface,
The block has at least three sipes extending in the tire width direction, at least one side in the tire width direction being open to the circumferential groove,
The at least three sipes include a first sipe and a second sipe,
The first sipe is a linear vertical flask sipe that extends linearly when viewed from the tread surface, and has a linear portion extending vertically from the tread surface when viewed in a cross section in the sipe depth direction, and has a flask shape having an expanded portion on the sipe bottom side,
The tire is characterized in that the second sipe is a wavy flask sipe that extends in a wave shape with at least three or more ridges on each side when viewed from the tread surface, and has a flask shape with a widened portion on the sipe bottom side when viewed in a cross-section in the sipe depth direction. The tire according to claim 1, wherein, of the at least three sipes in the block, only the sipe on the center side in the tire circumferential direction within the block is the first sipe. The tire according to claim 2, wherein, of the at least three sipes in the block, only one sipe on the center side in the tire circumferential direction within the block is the first sipe. The tire according to claim 2 or 3, wherein, when viewed from the tread surface, the average distance in the tire circumferential direction between the first sipe and the second sipe is shorter than the average distance in the tire circumferential direction between the second sipe and the tire circumferential edge of the block. The first sipes and the second sipes are provided in a plurality of blocks adjacent to each other in a tire width direction,
The tire according to any one of claims 1 to 3, wherein, between two of the blocks adjacent in the tire width direction, directions in which the ridges of the second sipes extend are opposite to each other in the tire circumferential direction. The first sipe is a protruding sipe having a protrusion protruding from a sipe wall on one side of the first sipe and extending in a sipe depth direction,
The tire according to any one of claims 1 to 3, wherein the protrusion of the first sipe has a length in a sipe depth direction that is equal to or greater than half the sipe depth and extends in the sipe depth direction from the tread surface. The tire according to claim 6, wherein within the block, the direction in which the protrusion of the first sipe protrudes from the sipe wall is opposite in the tire circumferential direction to the direction in which the ridge of the second sipe protrudes.

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