JP7422583B2 - pneumatic tires - Google Patents

Description

The present disclosure relates to pneumatic tires.

2. Description of the Related Art Studless tires are known that have a low coefficient of friction and ensure driving performance on icy roads (ice performance). For example, Patent Document 1 has a plurality of blocks as tread land partitioned by main grooves and slits, and sipes provided in each block. The ice performance is enhanced by the edge effect and water removal effect of the sipes, and the ice performance is further enhanced by the traction effect of the slits.

However, since the blocks serving as the tread land are easy to move, uneven wear tends to occur. As uneven wear progresses, the ground contact of the tire's contact patch with the road surface deteriorates, resulting in a reduction in ice performance.

JP2012-250610A

The present disclosure provides a pneumatic tire that achieves both suppression of uneven wear and improvement of ice performance.

The pneumatic tire of the present disclosure includes a land extending in the circumferential direction of the tire, and the land has a first land opening at a land end on a first side in the tire width direction and spaced apart from a land end on a second side in the tire width direction. a slit, a second slit that is spaced apart from the land edge on the first side and opens to the land edge on the second side, and formed by each of the first slit and the second slit, and is wider than the maximum width of the land. The first slits and the second slits are arranged alternately in the circumferential direction of the tire, and the narrow land width portion has one narrow land width portion in the center of the tire circumferential direction. The first sipe extends in the width direction of the tire and divides the narrow land width portion.

FIG. 1 is a developed view showing an example of a tread surface of a pneumatic tire of the present disclosure. An enlarged development view showing shoulder land, quarter land, and center land. An enlarged development view showing shoulder land, quarter land, and center land. An enlarged development view showing the quarter land.

Hereinafter, one embodiment of the present disclosure will be described with reference to the drawings.

FIG. 1 is a developed view of a tread surface Tr provided in a pneumatic tire PT (hereinafter also simply referred to as "tire PT") of the present embodiment. The vertical direction in FIG. 1 corresponds to the tire circumferential direction CD, and the horizontal direction in FIG. 1 corresponds to the tire width direction WD. As shown in FIG. 1, the tread pattern formed on the tread surface Tr is a rib-shaped pattern in which each land continuously extends in the tire circumferential direction. The tire PT of this embodiment is a heavy load tire mounted on a truck or a bus.

The tread surface Tr of the tire PT is provided with four main grooves 61, 61, 62, and 62 that extend continuously in the tire circumferential direction CD. In this embodiment, there are four main grooves, but the number is not limited to this. It is possible to have three or more main grooves. The present embodiment includes a shoulder main groove 62 located at the outermost side in the tire width direction WD, and a center main groove 61 located inside the shoulder main groove 62 in the tire width direction WD. Furthermore, the main groove may have a groove width that is, for example, 3% or more of the distance between the ground contact edges CE and CE (dimension in the tire width direction WD), although this is not particularly limited. Further, the main groove may have a groove width of 7.0 mm or more, for example, although it is not particularly limited. Although the main groove is not particularly limited, for example, the main groove is continuous in the tire circumferential direction CD, has the deepest groove depth within the tread surface Tr, and has a TWI (tread wear indicator) in the groove that indicates the usage limit due to wear. ) may be provided.

In this specification, a slit means a groove that is narrower than the main groove and wider than the sipe. Sipe means a groove less than 1.5 mm wide.

The contact edge CE is the outermost position of the contact patch in the width direction of the tire when the tire PT is mounted on a regular rim, filled with the regular internal pressure, placed vertically on a flat road surface, and the regular load is applied. It is.

A regular rim is a rim defined for each tire by the standard in the standard system that includes the standard on which the tire is based, for example, a standard rim for JATMA, and a "Measuring Rim" for TRA and ETRTO. Regular internal pressure is the air pressure specified for each tire by each standard in the standard system including the standard on which the tire is based, and for JATMA it is the maximum air pressure, and for TRA it is the air pressure specified in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". ”, if it is ETRTO, it is “INFLATION PRESSURE”. Note that if the tire is for a passenger car, the pressure is 180 kPa, and if the tire is marked as Extra Load or Reinforced, the pressure is 220 kPa. The regular load is the load specified for each tire by each standard in the standard system including the standard on which the tire is based, and for JATMA it is the maximum load capacity, for TRA it is the maximum value listed in the table above, For ETRTO, it is "LOAD CAPACITY", but if the tire is for a passenger car, it is 88% of the corresponding load of internal pressure.

<Slit on shoulder land 1>
As shown in FIGS. 1 and 2, the tire PT has shoulder lands 1 extending in the tire circumferential direction CD at both ends of the tread surface Tr in the tire width direction. The shoulder land 1 is arranged outside the outermost main groove 62 in the tire width direction WD. The shoulder land 1 is divided into an outermost main groove 62 and a ground contact edge CE in the tire width direction WD. The shoulder land 1 extends continuously in the tire circumferential direction CD. The shoulder land 1 has a plurality of first slits 11 and a plurality of second slits 12. The first slit 11 opens at the land edge 1a (ground contact edge CE) of the first side WD1 in the tire width direction WD, and is spaced apart from the land edge 1b (main groove 62) of the second side WD2 in the tire width direction WD, It is blocked within shoulder land 1. The second slit 12 opens at the land edge 1b (main groove 62) of the second side WD2 in the tire width direction WD, and is spaced apart from the land edge 1a (ground contact edge CE) of the first side WD1 in the tire width direction WD, It is blocked within shoulder land 1. The first slits 11 and the second slits 12 have different positions in the tire circumferential direction CD, and are arranged alternately in the tire circumferential direction CD. The length of the first slit 11 and the second slit 12 in the tire width direction WD is 40% or more, more preferably 50% or more of the maximum width W11 of the shoulder land 1 in the tire width direction WD.

<Slit in center land 2>
The tire PT has a center land 2 extending in the tire circumferential direction CD at the center portion of the tread surface Tr in the tire width direction. Center land 2 is the land closest to the tire equator TE. The center land 2 is divided into a pair of main grooves 61, 61. The center land 2 extends continuously in the tire circumferential direction CD. In this embodiment, the center land 2 is provided on the tire equator TE, but is not limited thereto. The center land 2 has a plurality of first slits 21 and a plurality of second slits 22. The first slit 21 opens at the land edge 2a (main groove 61) of the first side WD1 in the tire width direction WD, and is spaced apart from the land edge 2b (main groove 61) of the second side WD2 in the tire width direction WD, It is blocked within Center Riku 2. The second slit 22 opens at the land edge 2b (main groove 61) of the second side WD2 in the tire width direction WD, and is spaced apart from the land edge 2a (main groove 61) of the first side WD1 in the tire width direction WD. , is blocked within Center Land 2. The first slits 21 and the second slits 22 have different positions in the tire circumferential direction CD, and are arranged alternately in the tire circumferential direction CD. The length of the first slit 21 and the second slit 22 in the tire width direction WD is 40% or more, more preferably 50% or more of the maximum width W21 of the center land 2 in the tire width direction WD.

<Slit in quarter land 3>
The tire PT has a quarter land 3 extending in the tire circumferential direction CD between a shoulder land 1 and a center land 2. The quarter land 3 is divided into a pair of main grooves 61 and 62. The quarter land 3 extends continuously in the tire circumferential direction CD. The quarter land 3 has a plurality of first slits 31 and a plurality of second slits 32. The first slit 31 opens at the land edge 3a (main groove 62) of the first side WD1 in the tire width direction WD, and is spaced apart from the land edge 3b (main groove 61) of the second side WD2 in the tire width direction WD. Blocked within Quarter Land 3. The second slit 32 opens at the land edge 3b (main groove 61) of the second side WD2 in the tire width direction WD, and is spaced apart from the land edge 3a (main groove 62) of the first side WD1 in the tire width direction WD. , is blocked within Quarter Land 3. The first slits 31 and the second slits 32 have different positions in the tire circumferential direction CD, and are arranged alternately in the tire circumferential direction CD. The length of the first slit 31 and the second slit 32 in the tire width direction WD is 40% or more, more preferably 50% or more of the maximum width W31 of the quarter land 3 in the tire width direction WD.

In addition, in FIG. 1, shoulder land 1 and quarter land 3 on the left side are labeled and explained, but shoulder land 1 and quarter land 3 on the right side of the same figure have their patterns reversed by rotation. .

<Narrow land area>
As shown in FIG. 1, in each land 1, 2, 3, the first slit 11, 21, 31 and the second slit 12, 22, 32 form a narrow land width portion 13, 23, 33, respectively. There is. The width of the narrow land width portions 13, 23, 33 in the tire width direction WD is narrower than the maximum width W11, W21, 31 of each land (shoulder land 1, center land 2, quarter land 3) in the tire width direction WD. . The narrow land width portions 13, 23, 33 formed by the first slits 11, 21, 31 and the narrow land width portions 13, 23, 33 formed by the second slits 12, 22, 32 are arranged in the circumferential direction of the tire. They are arranged alternately in the CD, and their positions in the tire width direction WD and the tire circumferential direction CD are different from each other.

In each land 1, 2, 3, notches 14, 24, 34 open at the land ends 1b, 2b, 3b corresponding to the first slits 11, 21, 31, and corresponding to the second slits 12, 22, 32. Notches 14, 24, and 34 that open at the land ends 1a, 2a, and 3a are formed. The notches 14, 24, 34 corresponding to the first slits 11, 21, 31 are arranged at positions sandwiching the narrow land width portions 13, 23, 33 together with the first slits 11, 21, 31. The notches 14, 24, 34 corresponding to the second slits 12, 22, 32 are arranged at positions sandwiching the narrow land width portions 13, 23, 33 together with the second slits 12, 22, 32. Although the notch is a type of slit, it has a shorter length in the tire width direction WD than the first slit and the second slit.

One first sipe 15, 25, 35 is formed at the center of each narrow land width portion 13, 23, 33 in the tire circumferential direction. The first sipes 15, 25, and 35 extend in the tire width direction WD and divide the narrow land width portions 13, 23, and 33, respectively. The first sipes 15, 25, 35 open into corresponding slits and notches, respectively. In the present embodiment, the first sipes 15, 25, and 35 have a wavy shape on the tread surface when new in plan view, but the shape is not limited, and may be linear, for example. Of course, it is preferable for the first sipes 15, 25, and 35 to be wavy sipes rather than straight sipes, since this is more effective in suppressing the movement of the land, from the viewpoint of suppressing uneven wear. If the narrow land width section is divided by two or more first sipes, the rigidity of the narrow land width section will be lowered, and the narrow land width section will move too much, causing uneven wear, which is not preferable.

As shown in FIGS. 1 and 2, one first sipe 15, 25, 35 divides each narrow land width portion 13, 23, 33. Each of the lands 1, 2, and 3 continues as land in the tire circumferential direction CD, but is divided into pseudo small blocks G1, G1 by the first sipes 15, 25, and 35 (see FIG. 4).

As shown in FIG. 2, the lengths L13, L23, L33 of the narrow land width portions 13, 23, 33 in the tire width direction WD are the maximum widths W11, W21 of the respective lands 1, 2, 3 in the tire width direction WD. , W31 is preferably 10% or more and 60% or less. Explaining using the symbols shown in FIG. 2, W11×10%≦L13≦W11×60%, W21×10%≦L23≦W21×60%, and W31×10%≦L33≦W31×60%. This is to suppress uneven wear and ensure running stability on snowy roads (snow performance) due to snow column shear force.
Furthermore, lengths L13, L23, and L33 of the narrow land width portions 13, 23, and 33 in the tire width direction WD are 20% or more and 40% or less of the maximum widths W11, W21, and W31 of each land in the tire width direction WD. It is preferable that
If the length of the narrow land width portions 13, 23, 33 in the tire width direction WD is less than 10% of the maximum width W11, W21, W31 of each land in the tire width direction WD, adjacent small blocks G1, G1 (See Fig. 4) The effect of supporting each other becomes weaker, and sufficient block rigidity cannot be ensured, leading to uneven wear.
If the length of the narrow land width portions 13, 23, 33 in the tire width direction WD exceeds 60% of the maximum width W11, W21, W31 of each land in the tire width direction WD, the first slit, the second slit, the notch As the groove volume becomes smaller, this becomes a factor in deterioration of driving performance on snowy roads (snow performance) due to snow column shear force.

<Overlapping area>
As shown in FIG. 3, in each of the shoulder land 1, the center land 2, and the quarter land 3, the first slits 11, 21, 31 and the second slits 12, 22, 32 are adjacent to each other in the tire circumferential direction CD. , when viewed along the tire circumferential direction CD, have overlapping regions Ar1, Ar2, and Ar3 that partially overlap. The length of the overlapping regions Ar1, Ar2, Ar3 in the tire width direction WD is preferably 5% or more and 40% or less of the maximum width W11, W21, W31 of each land in the tire width direction WD. Explaining using the symbols shown in FIG. 3, W11×5%≦Ar1≦W11×40%, W21×5%≦Ar2≦W21×40%, and W31×5%≦Ar3≦W31×40%.
If the length of the overlapping regions Ar1, Ar2, Ar3 in the tire width direction WD is less than 5% of the maximum width W11, W21, W31 of each land in the tire width direction WD, the overlapping regions Ar1, Ar2, Ar3 are provided. The effect of improving traction due to this is poor.
If the length of the overlapping regions Ar1, Ar2, Ar3 in the tire width direction WD exceeds 40% of the maximum width W11, W21, W31 of each land in the tire width direction WD, the land rigidity decreases and uneven wear occurs. It becomes a factor.
Note that the first slits 11, 21, 31 and the second slits 12, 22, 32, which are adjacent to each other in the tire circumferential direction CD, have overlapping regions Ar1, Ar2, Ar3 in which positions in the tire width direction WD partially overlap. It can be said that it does.
In addition, the first slits 11, 21, 31 and the second slits 12, 22, 32, which are adjacent to each other in the tire circumferential direction CD, are defined by the tire meridian cross section when projected along the tire circumferential direction CD with respect to the tire meridian cross section. It can also be said that they overlap at the top.

The lengths in the tire width direction WD of the overlapping regions Ar1, Ar2, and Ar3 are longer than the lengths L14, L24, and L34 in the tire width direction WD of the notches 14, 24, and 34 that open in the main groove in each land. If explained using the symbols shown in FIG. 3, Ar1>L14, Ar2>L24, and Ar3>L34. It is possible to effectively exert traction while suppressing the occurrence of uneven wear. For example, if the length in the tire width direction WD of the overlapping region Ar1 is shorter than the length L14 in the tire width direction WD of the notch 14 that opens in the main groove on each land, if the notch is significantly long, or if the notch is It may be short and the overlapping region may be even shorter than the notch. If the notch is extremely long, the block rigidity decreases, causing uneven wear. If the notch is short and the overlapping region is even shorter than the notch, the traction element combined with the slit and notch will be insufficient, resulting in insufficient traction.

As shown in FIG. 3, the length of the overlapping region Ar2 of the center land 2 in the tire width direction WD is longer than the length of the overlapping region Ar1 of the shoulder land 1 in the tire width direction WD. In this embodiment, when the length of the overlapping region Ar3 of the quarter land 3 in the tire width direction WD is indicated as Ar3, Ar2>Ar3>Ar1. Although the length is explained here, it is preferable to specify it as a percentage of the maximum width of the land. That is, the ratio (Ar2/W21) of the overlapping area Ar2 of the center land 2 in the tire width direction WD to the maximum width W21 of the center land 2 is the ratio (Ar2/W21) of the overlapping area Ar1 of the shoulder land 1 in the tire width direction to the maximum width W11 of the shoulder land 1. It is preferable that the ratio is larger than the ratio of WD (Ar1/W11). In this embodiment, (Ar2/W21)>(Ar3/W31)>(Ar1/W11).
In a heavy-duty tire, the ground pressure is high near the tire equator TE, and the traction provided by the slits 21 and 22 is likely to be effective, so the overlapping region Ar2 is made relatively large. Since the shoulder region, which is the end region in the tire width direction WD, is a region that is prone to uneven wear, the overlapping region Ar1 is made relatively small. By making such a size relationship, uneven wear can be suppressed while improving the traction effect.

<Positional relationship of slits>
As shown in FIGS. 1 and 2, the tire PT has a first land (quarter land 3) on the first side and a second land (quarter land 3) on the second side that are adjacent to each other and sandwich the main groove 61 closest to the tire equator TE. center land 2), a third land on the first side (shoulder land 1) and a fourth land on the second side (quarter land 3) which are adjacent to each other and sandwich the main groove 62 located at the outermost side in the tire width direction WD. , has.

The opening of the second slit 32 of the first land (quarter land 3) and the opening of the first slit 21 of the second land (center land 2) do not overlap each other when viewed in the tire width direction WD. The slits 32 and 21 are shifted in position in the tire circumferential direction CD. The opening of the second slit 32 of the first land (quarter land 3) and the opening of the first slit 21 of the second land (center land 2) are separated in the tire circumferential direction CD.
The opening of the second slit 12 of the third land (shoulder land 1) and the opening of the first slit 31 of the fourth land (quarter land 3) at least partially overlap each other when viewed in the tire width direction WD. The positions of the slits 12 and 31 in the tire circumferential direction CD correspond.
As shown in FIG. 2, when a virtual line V2 is drawn that passes through the opening end of each slit 32, 21 and is parallel to the tire width direction WD, it can be seen that the openings of the slits 32, 21 do not overlap with each other.
When a virtual line V2 is drawn that passes through the opening end of each slit 12, 31 and is parallel to the tire width direction WD, it can be seen that the openings of the slits 12, 31 at least partially overlap each other.

As shown in FIG. 2, the extension line V1 of the center line of the second slit 32 of the first land (quarter land 3) does not enter the first slit 21 of the second land (center land 2). The slits 32 and 21 are shifted in position in the tire circumferential direction CD.
Further, V1 of the center line of the second slit 12 of the third land (shoulder land 1) enters the first slit 31 of the fourth land (quarter land 3). The positions of the slits 12 and 31 in the tire circumferential direction CD correspond.

<Slit depth>
The depth of each slit 11, 12, 21, 22, 31, 32 is determined from the depth of the main grooves 61, 62 from the viewpoint of ensuring winter performance (snow performance) and preventing uneven wear and deterioration of wear resistance performance. It is preferable that the height is 50% or more and 90% or less. This is because if the depth of the slit is less than 50% of the depth of the main groove, the traction performance after the middle stage of wear will decrease and the winter performance will deteriorate. If the depth of the slit is deeper than 90% of the depth of the main groove, the block rigidity will decrease, leading to worsening of abrasion and uneven wear.

The slits 21 and 22 in the center land 2 are deeper than the slits 11 and 12 in the shoulder land 1. If the slits 21 and 22 of the center land 2 are deeper than the slits 11 and 12 of the shoulder land 1, they will contribute to the edge effect and improve ice performance. Further, it is preferable that the slits 31 and 32 in the quarter land 3 be shallower than the slits 21 and 22 in the center land 2 from the viewpoint of uneven wear resistance, but the present invention is not limited thereto. If the quarter land 3 is to play the same role as the shoulder land 1, the slits 11 and 12 in the shoulder land 1 may have the same depth as the slits 21 and 22 in the center land 2.

<Sipe>
As shown in FIG. 2, a plurality of sipes are formed on each of the shoulder land 1, the center land 2, and the quarter land 3. The sipe is formed by a cut having a width of less than 1.5 mm. Each of the lands 1, 2, and 3 has a circumferential sipe 52, a closed sipe 53, and a semi-open sipe 54.

As shown in FIG. 2, the circumferential sipe 52 is a sipe with a wavy tread shape, and extends in the tire circumferential direction CD at the center portion of each land 1, 2, 3 in the tire width direction, and connects the first slits 11, 21. , 31 and the second slits 12, 22, 32, and divide the lands 1, 2, 3 into left and right sides in the tire width direction WD. Therefore, in this embodiment, from the viewpoint of suppressing the movement of the divided land and reducing uneven wear, the circumferential sipe 52 has a tread shape of a wave-like sipe, and the shape changes along the depth direction. It is a three-dimensional sipe that includes a part. However, the present invention is not limited to this, and the circumferential sipe 52 may be a two-dimensional sipe whose shape does not change along the depth direction.
The closed sipe 53 is a sipe with a wavy tread shape, extends in the tire width direction WD, and closes within each of the lands 1, 2, and 3.
The semi-open sipe 54 is a sipe with a wavy tread shape, and extends in the tire width direction WD at the center in the tire circumferential direction. The semi-open sipe 54 has a first end 54a that is closed within each land 1, 2, and 3, and a second end 54b that opens at the land end of each land 1, 2, and 3.

Although the closed sipe 53 and the semi-open sipe 54 are sipes with wavy tread shapes, the tread shape is not limited to this, and the tread shape may be straight. Further, the closed sipe 53 and the semi-open sipe 54 are two-dimensional sipes whose shape does not change along the depth direction, but they may be three-dimensional sipes that include a portion whose shape changes along the depth direction. .

As shown in FIGS. 1, 2, and 4, the first sipes 15, 25, and 35 of the narrow land width portions 13, 23, and 33 form each of the lands 1, 2, and 3 into pseudo small blocks G1, G1. be divided. Furthermore, the small block G1 is divided into left and right small blocks in the tire width direction WD by the circumferential sipe 52, and the small block is further partially divided in the tire circumferential direction CD by the semi-open sipe 54. As a result, although it is land as a whole, a plurality of pseudo small blocks G2, G3, G4, G5 (4 for center land 2 and quarter land 3) are divided into one small block G1 in the tire circumferential direction CD. will be formed. As a result, compared to the case of adopting a block pattern divided by slits, while suppressing the occurrence of uneven wear due to the land, pseudo small blocks G2, G3, G4, and G5 that are smaller than the land can be used to create traction elements or resistance. It is possible to increase sideslip elements and improve ice performance. However, since the closed sipe 53 is provided and the semi-open sipe 54 is provided at the center of the small block G1 in the tire circumferential direction, the traction element is increased while maintaining the rigidity balance within the small blocks G2, G3, G4, and G5. This makes it possible to improve ice performance while suppressing the occurrence of uneven wear.
Although not particularly limited, it is preferable that the circumferential sipe 52 has a wavy tread shape. The wall surfaces of the circumferential sipes 52 come into contact with each other, making it possible to suppress excessive movement of the small blocks.

As shown in FIG. 2, the small block G6 closest to the ground contact edge CE, which is divided by the circumferential sipes 52 and the narrow land width portion 13, is easily affected by lateral force, so all the sipes are closed. Only Sipe 53 is used.

From the viewpoint of improving ice performance and suppressing the occurrence of uneven wear, the width Wo of the first sipes 15, 25, 35 and the circumferential sipe 52 is thicker than the width Ws of the semi-open sipe 54; It is preferable that Ws is thicker than the width Wc of the closed sipe 53. Wo>Ws>Wc. By making the width Wo of the open sipe (first sipe, circumferential sipe 52) relatively thicker, it is possible to improve ice performance while ensuring land rigidity compared to a block pattern composed of grooves. Become. By making the width Wc of the closed sipe 53 relatively thin, it is possible to suppress the movement of the block and reduce the cause of wear or uneven wear. By setting the width of the semi-open sipe 54 to be an intermediate width between the open sipe (first sipe, circumferential sipe 52) and the closed sipe 53, it is possible to balance block rigidity and ice performance. Of course, if these aspects do not matter, the widths of all the sipes may be the same, or the size relationship of the widths can be changed in various ways.

Note that the depth of the sipe in this specification is preferably 50% or more and 80% or less of the depth of the main groove. If the depth of the sipes is less than 50% of the depth of the main groove, the ice performance as a winter tire will be insufficient. If the depth of the sipe is deeper than 80% of the depth of the main groove, the rigidity of the land decreases, causing uneven wear.

As described above, the pneumatic tire PT of the present embodiment includes the land 1 (2; 3) extending in the tire circumferential direction CD, and the land 1 (2; 3) is located on the first side WD1 in the tire width direction WD. A first slit 11 (21; 31) that opens at the land end 1a (2a; 3a) and is spaced apart from the land end 1b (2b; 3b) on the second side WD2 in the tire width direction WD; A second slit 12 (22; 32) that opens to the land end 1b (2b; 3b) of the second side WD2 and is spaced apart from the land end 1a (2a; 3a) of the first side WD1 in the tire width direction WD; The narrow land width portion 13 (23) is formed by the slit 11 (21; 31) and the second slit 12 (22; ; 33), the first slits 11 (21; 31) and the second slits 12 (22; 32) are arranged alternately in the tire circumferential direction CD, and the narrow land width portion 13 (23; 33) has one first sipe 15 (25; 35) at the center in the tire circumferential direction, and the first sipe 15 (25; 35) extends in the tire width direction WD. It is preferable that the

Since the land 1 (2; 3) extends continuously in the tire circumferential direction CD, it can ensure rigidity compared to a block and suppress uneven wear. Furthermore, the first slits 11 (21; 31) and the second slits 12 (22; 32) arranged alternately in the tire circumferential direction CD ensure the traction element while maintaining the rigidity balance of the land 1 (2; 3). It becomes possible. Each slit 11, 12 (21, 22; 31, 32) forms a narrow land width portion 13 (23; 33), so that the narrow land width portion 13 (23; 33) 22; 31, 32) and alternately arranged in the tire circumferential direction CD, the rigidity of the land can be maintained in a well-balanced manner, and uneven wear can be suppressed. However, since the narrow land width portion 13 (23; 33) is divided by the first sipe 15 (25; 35), the land continuous in the tire circumferential direction CD is pseudo-divided into small block groups G1, G1. Therefore, compared to block groups divided by slits, it is possible to suppress uneven wear while increasing traction elements and ensuring ice performance.
If the narrow land width portion 13 (23; 33) is divided by two or more sipes, the narrow land width portion 13 (23; 33) becomes more mobile due to decreased rigidity, resulting in uneven wear. On the other hand, by reducing the number of first sipes 15 (25; 35) formed in the narrow land width portion 13 (23; 33) to one, it is possible to suppress uneven wear.
Therefore, it is possible to both improve ice performance due to the traction element and suppress uneven wear. Furthermore, by suppressing uneven wear, the ground contact properties of the ground contact surface are improved, and it becomes possible to improve the ice performance due to the water removal effect of scratches and sipes.

As in this embodiment, it is preferable that all the land forming the ground plane be the above-mentioned land. As a result, since all of the land is the above-mentioned land, the grounding performance of the entire ground contact surface with respect to the road surface is improved, and it is possible to improve the ice performance.

As in the present embodiment, the first slit 11 (21; 31) and the second slit 12 (22; 32) that are adjacent to each other in the tire circumferential direction CD are partially It is preferable to have overlapping regions Ar1 (Ar2; Ar3) that overlap each other. As a result, the total length of the two slits 11 and 12 is greater than or equal to the maximum width W11 of the land 1, making it possible to increase the traction factor and improve the ice performance. Furthermore, since the slit is longer than in the case where there is no overlap region Ar1 (Ar2; Ar3), it is also possible to improve snow performance due to snow column shear force.

As in the present embodiment, the length L13 (L23; L33) of the narrow land width portion 13 (23; 33) in the tire width direction WD is the maximum width W11 (L23; L33) of the land 1 (2; 3) in the tire width direction WD. W21; W31) is preferably 10% or more and 60% or less. This makes it possible to both suppress uneven wear and ensure running stability on snowy roads (snow performance) due to snow column shear force.

As in this embodiment, the land 1 (2; 3) opens to the land edges 1a, 1b (2a, 2b; 3a, 3b), and together with the slit 11 (21, 22; 31, 32), the land narrow part 13 (23; 33), and the length of the overlap region Ar1 (Ar2; Ar3) in the tire width direction WD is the notch 14 (24; 24; 34) is preferably longer than the length L14 (L24; L34) in the tire width direction WD. This makes it possible to effectively exert traction while suppressing the occurrence of uneven wear.

As in this embodiment, the land 1 (2; 3) includes a shoulder land 1 located outside the outermost main groove 62 in the tire width direction WD, and a center land that is the land closest to the tire equator TE. The ratio of the tire width direction WD to the maximum width W21 of the overlapping area Ar2 of the center land 2 (Ar2/W21) is the ratio of the tire width direction WD to the maximum width W11 of the overlapping area Ar1 of the shoulder land 1. It is preferable that the ratio is larger than the ratio (Ar1/W11). In heavy-duty tires, the ground pressure is high near the tire equator TE, and the traction by the slits 21 and 22 is likely to be effective, so the overlapping region Ar2 is made relatively large, and the shoulder region, which is the end region in the tire width direction WD, prevents uneven wear. Since it is an area where it is easy to overlap, the overlapping area Ar1 is made relatively small. By making such a size relationship, uneven wear can be suppressed while improving the traction effect.

As in the present embodiment, the land 1 (2; 3) includes the first land (3) adjacent to the first side WD1 of the first main groove 61 closest to the tire equator TE, and the first land (3) adjacent to the first side WD1 of the first main groove 61 closest to the tire equator TE. A second land (2) adjacent to the second side WD2, a third land (1) adjacent to the first side WD1 of the second main groove 62 located at the outermost side in the tire width direction WD, and a third land (1) adjacent to the first side WD1 of the second main groove 62 located at the outermost side in the tire width direction WD. They are respectively arranged as the fourth land (3) adjacent to the second side WD2, and the opening of the second slit 32 of the first land (3) and the opening of the first slit 21 of the second land (2) do not overlap each other when viewed in the tire width direction WD, and the opening of the second slit 12 of the third land (1) and the opening of the first slit 31 of the fourth land (3) are in the tire width direction. Preferably, they overlap each other at least partially. As a result, by shifting the position of the slits 21 and 32 in the tire circumferential direction CD from the center region near the tire equator TE where the ground contact pressure is high, the frequency of the slits appearing in the ground contact surface during rolling increases, and the slits provide traction. It becomes possible to effectively demonstrate the effect. The shoulder area near the contact edge CE has a lower ground contact pressure than the center area, so by aligning the positions of the slits 12 and 31 in the tire circumferential direction CD, a relatively long traction element can be exerted all at once, effectively suppressing the snow. It becomes possible to improve performance.

As in this embodiment, the land 1 (2; 3) includes a shoulder land 1 located outside the outermost main groove 62 in the tire width direction WD, and a center land that is the land closest to the tire equator TE. The slits 21 and 22 of the center land 2 are preferably deeper than the slits 11 and 12 of the shoulder land 1. As a result, if the slits 21 and 22 of the center land 2 are deeper than the slits 11 and 12 of the shoulder land 1, the edge effect of the center land 2 with high ground contact pressure increases, and it becomes possible to improve the ice performance. Furthermore, since the slit in the shoulder land 1 is made relatively shallow, uneven wear can be suppressed. Furthermore, since the slits 21 and 22 of the center land 2 remain in the final stage of wear, it is possible to ensure the edge effect of the slits in the center land 2 with high ground contact pressure even in the final stage of wear.

As in this embodiment, the land 1 (2; 3) includes a circumferential sipe 52 (second sipe), a closed sipe 53 (third sipe), and a semi-open sipe 54 (fourth sipe). , the circumferential sipe 52 (second sipe) extends in the tire circumferential direction CD at the center of the tire width direction of the land 1 (2; 3), and includes the first slit 11 (21; 31) and the second slit 12 (22; 32), the closed sipe 53 (third sipe) extends in the tire width direction WD and is closed in the land 1 (2; 3), and the semi-open sipe 54 (fourth sipe) In the center of the tire circumferential direction of the region G1 separated by the narrow land width portions 13 (23; 33) adjacent to each other in the circumferential direction CD, a first section extends in the tire width direction WD and is closed within the land 1 (2; 3). It is preferable to have a first end 54a and a second end 54b opening at the land end of land 1 (2; 3).
As a result, land 1 (2; 3) is divided into small blocks in the tire width direction WD by the circumferential sipe 52 (second sipe), and land 1 (2; 3) is divided by the semi-open sipe 54 (fourth sipe). A plurality of (four in the center land 2 and quarter land 3) small blocks G2, G3, G4, and G5 are pseudo-divided in the tire circumferential direction CD and divided in the tire circumferential direction CD. Therefore, compared to the case of adopting a block pattern divided by slits, the occurrence of uneven wear is suppressed by the rib-shaped land continuous in the circumferential direction of the tire, and pseudo small blocks G2, G3, smaller than the land are suppressed. G4 and G5 can increase the traction element and improve ice performance. At the same time, the closed sipe 53 (third sipe) increases the traction element while suppressing a decrease in the rigidity of the land, and the semi-open sipe 54 (fourth sipe) that reduces the rigidity of the land is located at the center in the tire circumferential direction of the small block G1. Since it is provided in the small blocks G2, G3, G4, and G5, the number of traction elements can be increased while maintaining the rigidity balance within the small blocks G2, G3, G4, and G5, making it possible to improve ice performance while suppressing the occurrence of uneven wear. .
Although not particularly limited, it is preferable that the circumferential sipe 52 (second sipe) has a wavy tread shape. The wall surfaces of the circumferential sipes 52 (second sipes) come into contact with each other, suppressing excessive movement of the small blocks, and making it possible to suppress uneven wear caused by the formation of small blocks.

In the above description, a combination of the circumferential sipe 52, the closed sipe 53, and the semi-open sipe 54 is applied to one land, but the present invention is not limited to this. For example, each sipe can be applied on land alone or in combination with any other sipe. For example, when the circumferential sipes 52 are employed, the land can be divided into left and right sides in the tire width direction to create pseudo small blocks. When the semi-open sipe 54 is adopted, the rigidity within these small blocks G2, G3 (G4, G5) is increased while dividing into two small blocks G2, G3 (G4, G5) adjacent to each other in the tire circumferential direction CD. Traction elements can be increased while maintaining balance, making it possible to improve ice performance while suppressing uneven wear.

As in the present embodiment, the width Wo of the first sipes 15, 25, 35 and the circumferential sipe 52 (second sipe) is thicker than the width Ws of the semi-open sipe 54 (fourth sipe). The width Ws of the (fourth sipe) is preferably thicker than the width Wc of the closed sipe 53 (third sipe). This makes it possible to improve ice performance and prevent uneven wear.

Although the embodiments of the present disclosure have been described above based on the drawings, it should be understood that the specific configuration is not limited to these embodiments. The scope of the present disclosure is indicated not only by the description of the embodiments described above but also by the claims, and further includes all changes within the meaning and scope equivalent to the claims.

<Modified example>
(1) In the embodiment shown in FIG. 1, the center land 2 is provided on the tire equator TE, but is not limited thereto. For example, when there are three main grooves and the middle main groove is arranged on the tire equator TE, a pair of mutually adjacent center lands are arranged at positions sandwiching the middle main groove.

(2) In this embodiment, the notch 14 (24; 34) is provided, but the notch may not be provided. If there is no notch, the first sipes 15, 25, 35 open into the corresponding main groove or ground end.

(3) In this embodiment, an overlapping region is formed by the first slit and the second slit, but there may be no overlapping region.

(4) In this embodiment, regarding the relationship between the lengths of the overlapping regions Ar1, Ar2, and Ar3 in the tire width direction WD and the lengths L14, L24, and L34 of the notches 14, 24, and 34 in the tire width direction WD, Ar1> L14, Ar2>L24, Ar3>L34, but are not limited to this. For example, Ar1≦L14, Ar2≦L24, and Ar3≦L34 can be adopted as long as these viewpoints do not matter.

(5) Regarding the length in the tire width direction WD of the overlapping area Ar2 of the center land 2, the overlapping area Ar1 of the shoulder land 1, and the overlapping area Ar3 of the quarter land 3, Ar2>Ar3>Ar1, but it is not limited to this. For example, it is possible to adopt Ar2≦Ar3≦Ar1 as long as these aspects do not matter.

(6) The depths of the slits in the center land 2, the slits in the shoulder land 1, and the slits in the quarter land 3 are not limited to this embodiment, and may all be the same.

(7) Regarding the above set of slits, in this embodiment, since there are four main grooves, the first facing land is a set of center land 2 and quarter land 3, and the second facing land is a set of shoulder land 1. This is a group of 3 quarter land, but it is not limited to this. For example, if there are three main grooves, the pair of center lands are adjacent to each other across the middle main groove, and the pair of shoulder lands are arranged on the outside of each center land in the tire width direction. In this case, the first opposing land is a set of center land, and the second opposing land is a set of center land and shoulder land.

It is possible to apply the structure adopted in each of the above embodiments to any other embodiment. The specific configuration of each part is not limited to the embodiment described above, and various modifications can be made without departing from the spirit of the present disclosure.

It is possible to apply the structure adopted in each of the above embodiments to any other embodiment.

1...Shoulder land (land), 2...Center land (land), 3...Quarter land (land), Ar1, Ar2, Ar3...overlapping area, CD...tire circumferential direction, WD...tire width direction, WD1...tire width direction WD2...second side in the tire width direction, W11, W21, W31...land maximum width, 1a, 1b, 2a, 2b, 3a, 3b...land edge, 11, 21, 31...first slit, 12, 22, 32...Second slit, 13,23,33...Narrow land width portion, 15,25,35...First sipe, 52...Circumferential sipe (second sipe), 53...Closed sipe (third sipe) ), 54... Semi-open sipe (4th sipe), 14, 24, 34... Notch, 61... 1st main groove, 62... 2nd main groove, 2, 3... 1st landward, 1, 3... 2nd Against land

Claims (6)

Equipped with a land extending in the circumferential direction of the tire,
The land includes a first slit that opens at a land end on a first side in the tire width direction and is spaced apart from a land end on a second side in the tire width direction, and a first slit that opens at a land end on a first side in the tire width direction; a second slit opening at the side land edge, and a narrow land width portion formed by each of the first slit and the second slit and narrower in width than the maximum width of the land,
The first slits and the second slits are arranged alternately in the tire circumferential direction,
The narrow land width portion has one first sipe at the center in the tire circumferential direction, and the first sipe extends in the tire width direction and divides the narrow land width portion ,
The first slit and the second slit that are adjacent to each other in the tire circumferential direction have overlapping regions that partially overlap each other when viewed along the tire circumferential direction,
The land includes a notch that opens at the end of the land and sandwiches the narrow land width portion together with the slit,
The length of the overlapping region in the tire width direction is longer than the length of the notch in the tire width direction.
, pneumatic tires. Equipped with a land extending in the circumferential direction of the tire,
The land includes a first slit that opens at a land end on a first side in the tire width direction and is spaced apart from a land end on a second side in the tire width direction, and a first slit that opens at a land end on a first side in the tire width direction; a second slit opening at the side land edge, and a narrow land width portion formed by each of the first slit and the second slit and narrower in width than the maximum width of the land,
The first slits and the second slits are arranged alternately in the tire circumferential direction,
The narrow land width portion has one first sipe at the center in the tire circumferential direction, and the first sipe extends in the tire width direction and divides the narrow land width portion,
The first slit and the second slit that are adjacent to each other in the tire circumferential direction have overlapping regions that partially overlap each other when viewed along the tire circumferential direction,
The land is arranged as a shoulder land located outside the outermost main groove in the width direction of the tire, and a center land that is the land closest to the tire equator,
A pneumatic tire, wherein a ratio of the overlapping area of the center land in the tire width direction to the maximum width of the center land is larger than a ratio of the overlapping area of the shoulder land to the maximum width of the shoulder land in the tire width direction . Equipped with a land extending in the circumferential direction of the tire,
The land includes a first slit that opens at a land end on a first side in the tire width direction and is spaced apart from a land end on a second side in the tire width direction, and a first slit that opens at a land end on a first side in the tire width direction; a second slit opening at the side land edge, and a narrow land width portion formed by each of the first slit and the second slit and narrower in width than the maximum width of the land,
The first slits and the second slits are arranged alternately in the tire circumferential direction,
The narrow land width portion has one first sipe at the center in the tire circumferential direction, and the first sipe extends in the tire width direction and divides the narrow land width portion,
The land includes a first land adjacent to the first side of the first main groove closest to the tire equator, a second land adjacent to the second side of the first main groove, and the outermost land in the tire width direction. are respectively arranged as a third land adjacent to the first side of the second main groove and a fourth land adjacent to the second side of the second main groove,
The opening of the second slit of the first land and the opening of the first slit of the second land do not overlap each other when viewed in the tire width direction,
The opening of the second slit of the third land and the opening of the first slit of the fourth land are:
Pneumatic tires that overlap each other at least partially when viewed in the tire width direction . Equipped with a land extending in the circumferential direction of the tire,
The land includes a first slit that opens at a land end on a first side in the tire width direction and is spaced apart from a land end on a second side in the tire width direction, and a first slit that opens at a land end on a first side in the tire width direction; a second slit opening at the side land edge, and a narrow land width portion formed by each of the first slit and the second slit and narrower in width than the maximum width of the land,
The first slits and the second slits are arranged alternately in the tire circumferential direction,
The narrow land width portion has one first sipe at the center in the tire circumferential direction, and the first sipe extends in the tire width direction and divides the narrow land width portion,
The land is arranged as a shoulder land located outside the outermost main groove in the width direction of the tire, and a center land that is the land closest to the tire equator,
In the pneumatic tire, the slit in the center land is deeper than the slit in the shoulder land . Equipped with a land extending in the circumferential direction of the tire,
The land includes a first slit that opens at a land end on a first side in the tire width direction and is spaced apart from a land end on a second side in the tire width direction, and a first slit that opens at a land end on a first side in the tire width direction; a second slit opening at the side land edge, and a narrow land width portion formed by each of the first slit and the second slit and narrower in width than the maximum width of the land,
The first slits and the second slits are arranged alternately in the tire circumferential direction,
The narrow land width portion has one first sipe at the center in the tire circumferential direction, and the first sipe extends in the tire width direction and divides the narrow land width portion,
The land includes a second sipe, a third sipe, and a fourth sipe,
The second sipe extends in the tire circumferential direction at the center in the tire width direction on the land, and is open to both the first slit and the second slit,
The third sipe extends in the tire width direction and is closed in the land area,
The fourth sipe extends in the tire width direction in the tire circumferential center of a region separated by the land narrow portions adjacent to each other in the tire circumferential direction, and has a first end and the land end that are closed in the land. A pneumatic tire having a second end opening into the pneumatic tire. The pneumatic tire according to claim 5 , wherein a width of the second sipe is thicker than a width of the fourth sipe, and a width of the fourth sipe is thicker than a width of the third sipe.

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