JP2021154810A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire capable of both suppressing uneven wear and improving ice performance.SOLUTION: A tire has a land extending in a tire circumferential direction. The land has: a first slit which is opened to a first side land end in a tire width direction, and is separated from a second side land end in the tire width direction; a second slit which is separated from the first side land end, and is opened to the second side land end; and a land width narrow part which is formed by the first slit and the second slit, and whose width is narrower than the maximum width of the land. The first slit and the second slit are alternately disposed in the tire circumferential direction. The land width narrow part has one first sipe at the center in the tire circumferential direction. The first sipe extends in the tire width direction to divide the land width narrow part.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to pneumatic tires.

Studless tires that ensure running performance (ice performance) on icy roads with a low coefficient of friction are known. For example, Patent Document 1 has a plurality of blocks as a tread land partitioned by a main groove and a slit, and a sipe provided in each block. The ice performance is enhanced by the edge effect and water removal effect of the sipe, and the ice performance is further enhanced by the traction effect of the slit.

However, since the block as the tread land is easy to move, uneven wear is likely to occur. When uneven wear progresses, the ground contact surface of the tire with respect to the road surface deteriorates, and the ice performance is reduced.

Japanese Unexamined Patent Publication No. 2012-250610

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 tire circumferential direction, and the land is a first land that opens at the land end on the first side in the tire width direction and is separated from the land end on the second side in the tire width direction. It is formed by a slit, a second slit that is separated from the land end on the first side and opens to the land end on the second side, and the first slit and the second slit, respectively, and is larger than the maximum width of the land. It has a narrow land width portion, and the first slit and the second slit are alternately arranged in the tire circumferential direction, and the land narrow portion is one in the central portion in the tire circumferential direction. The first sipe extends in the tire width direction and divides the land width narrow portion.

The development view which shows an example of the tread surface of the pneumatic tire of this disclosure. Enlarged view showing shoulder land, quarter land and center land. Enlarged view showing shoulder land, quarter land and center land. Enlarged view showing quarter land.

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

FIG. 1 is a development view of a tread surface Tr included in the pneumatic tire PT of the present embodiment (hereinafter, also simply referred to as “tire PT”). 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 extends continuously in the tire circumferential direction. The tire PT of the present embodiment is a heavy-duty 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, 62 extending continuously in the tire circumferential direction CD. In the present embodiment, the number of main grooves is four, but the present invention is not limited to this. The number of main grooves can be three or more. In the present embodiment, the shoulder main groove 62 on the outermost side of the tire width direction WD and the center main groove 61 arranged inside the tire width direction WD of the shoulder main groove 62 are provided. Further, the main groove is not particularly limited, but may have, for example, a groove width of 3% or more of the distance between the ground contact ends CE and CE (dimension of WD in the tire width direction). Further, the main groove is not particularly limited, but may have a groove width of 7.0 mm or more, for example. The main groove is not particularly limited, but for example, it is continuous with the CD in the tire circumferential direction, the groove depth is the deepest in the tread surface Tr, and the inside of the groove is a TWI (tread wear indicator) indicating the usage limit due to wear. ) May be provided.

As used herein, a slit means a groove that is narrower than the main groove and wider than the sipe. Sipe means a groove with a width of less than 1.5 mm.

The ground contact end CE is the outermost position of the ground contact surface in the tire width direction when the tire PT is rim-assembled on the regular rim, the tire PT is placed vertically on a flat road surface with the regular internal pressure charged, and a regular load is applied. Is.

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

<Slit in shoulder land 1>
As shown in FIGS. 1 and 2, the tire PT has a shoulder land 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 the outermost main groove 62 in the tire width direction WD and the ground contact end CE. 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 end 1a (ground contact end CE) of the first side WD1 in the tire width direction WD, and is separated from the land end 1b (main groove 62) of the second side WD2 in the tire width direction WD. It is blocked in the shoulder land 1. The second slit 12 opens at the land end 1b (main groove 62) of the second side WD2 in the tire width direction WD, and is separated from the land end 1a (ground contact end CE) of the first side WD1 in the tire width direction WD. It is blocked in the shoulder land 1. The first slit 11 and the second slit 12 have different positions of the tire circumferential CDs from each other, and are alternately arranged in the tire circumferential CDs. The length of the tire width direction WD of the first slit 11 and the second slit 12 is 40% or more, more preferably 50% or more of the maximum width W11 of the tire width direction WD of the shoulder land 1.

<Slit at Center Land 2>
The tire PT has a center land 2 extending in the tire circumferential direction CD at the central 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 the present 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 end 2a (main groove 61) of the first side WD1 in the tire width direction WD, and is separated from the land end 2b (main groove 61) of the second side WD2 in the tire width direction WD. It is blocked in the center land 2. The second slit 22 opens at the land end 2b (main groove 61) of the second side WD2 in the tire width direction WD, and is separated from the land end 2a (main groove 61) of the first side WD1 in the tire width direction WD. , It is blocked in the center land 2. The first slit 21 and the second slit 22 have different positions of the tire circumferential CDs from each other, and are alternately arranged in the tire circumferential CDs. The length of the tire width direction WD of the first slit 21 and the second slit 22 is 40% or more, more preferably 50% or more of the maximum width W21 of the tire width direction WD of the center land 2.

<Slit in Quarter Land 3>
The tire PT has a quarter land 3 extending in the tire circumferential direction CD between the shoulder land 1 and the 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 end 3a (main groove 62) of the first side WD1 in the tire width direction WD, and is separated from the land end 3b (main groove 61) of the second side WD2 in the tire width direction WD. It is blocked in Quarter Land 3. The second slit 32 opens at the land end 3b (main groove 61) of the second side WD2 in the tire width direction WD, and is separated from the land end 3a (main groove 62) of the first side WD1 in the tire width direction WD. , It is blocked in the quarter land 3. The first slit 31 and the second slit 32 have different positions of the tire circumferential CDs from each other, and are alternately arranged in the tire circumferential CDs. The length of the tire width direction WD of the first slit 31 and the second slit 32 is 40% or more, more preferably 50% or more of the maximum width W31 of the tire width direction WD of the quarter land 3.

In FIG. 1, the shoulder land 1 and the quarter land 3 on the left side are described by adding a reference numeral, but the shoulder land 1 and the quarter land 3 on the right side of the figure are obtained by reversing the pattern by rotation. ..

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

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

One first sipe 15, 25, 35 is formed at the center of each of the narrow land width portions 13, 23, 33 in the tire circumferential direction. The first sipes 15, 25, and 35 extend in the tire width direction WD, respectively, and divide the land width narrow portions 13, 23, and 33, respectively. The first sipes 15, 25 and 35 are open to the corresponding slits and notches, respectively. In the present embodiment, the first sipe 15, 25, 35 has a wavy shape on the tread when new in a plan view, but the shape is not limited, and may be, for example, a straight line. Of course, it is preferable that the first sipes 15, 25, and 35 are wavy sipes rather than straight sipes, because the effect of suppressing the movement of the land is higher, and therefore, from the viewpoint of suppressing uneven wear. If the narrow land width portion is divided by two or more first sipes, the rigidity of the narrow land width portion becomes low, and the narrow land width portion moves too much, which causes uneven wear, which is not preferable.

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

As shown in FIG. 2, the lengths L13, L23, and L33 of the WD in the tire width direction of the land width narrow portions 13, 23, 33 are the maximum widths W11, W21 of the tire width direction WD of the land 1, 2, and 3, respectively. , W31 is preferably 10% or more and 60% or less. Explaining with reference numerals shown in FIG. 2, W11 × 10% ≦ L13 ≦ W11 × 60%, W21 × 10% ≦ L23 ≦ W21 × 60%, W31 × 10% ≦ L33 ≦ W31 × 60%. This is to achieve both suppression of uneven wear and ensuring running stability (snow performance) on snowy roads due to the shearing force of snow columns.
Further, the lengths L13, L23, L33 of the tire width direction WD of the land width narrow portions 13, 23, 33 are 20% or more and 40% or less of the maximum widths W11, W21, W31 of the tire width direction WD of each land. Is preferable.
If the length of the tire width direction WD of the land width narrow portions 13, 23, 33 is less than 10% of the maximum width W11, W21, W31 of the tire width direction WD of each land, adjacent small blocks G1, G1 The effect of supporting each other (see FIG. 4) is weakened, and sufficient block rigidity cannot be secured, which causes uneven wear.
If the length of the tire width direction WD of the land width narrow portions 13, 23, 33 exceeds 60% of the maximum width W11, W21, W31 of the tire width direction WD of each land, the first slit, the second slit, and the notch As the groove volume becomes smaller due to the above, it becomes a factor of deterioration of running performance (snow performance) on a snowy road due to the shearing force of the snow column.

<Overlapping area>
As shown in FIG. 3, in each of the land 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 adjacent to each other in the tire circumferential direction CD are , Has overlapping regions Ar1, Ar2, Ar3 that partially overlap when viewed along the tire circumferential direction CD. The length of the WD in the tire width direction of the overlapping regions Ar1, Ar2, Ar3 is preferably 5% or more and 40% or less of the maximum widths W11, W21, W31 in the tire width direction of each land. Explaining with reference numerals shown in FIG. 3, W11 × 5% ≦ Ar1 ≦ W11 × 40%, W21 × 5% ≦ Ar2 ≦ W21 × 40%, W31 × 5% ≦ Ar3 ≦ W31 × 40%.
If the length of the WD in the tire width direction of the overlapping regions Ar1, Ar2, Ar3 is less than 5% of the maximum widths W11, W21, W31 in the tire width direction of each land, the overlapping regions Ar1, Ar2, Ar3 are provided. The effect of improving traction is poor.
If the length of the WD in the tire width direction of the overlapping regions Ar1, Ar2, Ar3 exceeds 40% of the maximum widths W11, W21, and W31 in the tire width direction of each land, the rigidity of the land is reduced and uneven wear is caused. It becomes a factor to do.
The first slits 11, 21, 31 and the second slits 12, 22, 32 adjacent to each other in the tire circumferential direction CD have overlapping regions Ar1, Ar2, Ar3 in which the positions occupied in the tire width direction WD partially overlap. It can be said that it does.
Further, the first slits 11, 21, 31 and the second slits 12, 22, 32 adjacent to each other in the tire circumferential direction CD are the tire meridian cross sections when projected along the tire circumferential direction CD with respect to the tire meridian cross section. It can be said that they overlap on the above.

The length of the tire width direction WD of the overlapping regions Ar1, Ar2, Ar3 is longer than the tire width direction WD lengths L14, L24, L34 of the notches 14, 24, and 34 that open in the main groove in each land. Explaining with reference numerals 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, when the length of the tire width direction WD of the overlapping region Ar1 is shorter than the tire width direction WD length L14 of the notch 14 which opens in the main groove in each land, the notch is remarkably long or the notch is It may be short and the overlapping area may be even shorter than the notch. If the notch is extremely long, the block rigidity is lowered, which causes uneven wear. When the notch is short and the overlapping region is shorter than the notch, the traction element including the slit and the notch is insufficient, so that the traction is insufficient.

As shown in FIG. 3, the length of the tire width direction WD of the overlapping region Ar2 of the center land 2 is longer than the length of the tire width direction WD of the overlapping region Ar1 of the shoulder land 1. In the present embodiment, if the length of the WD in the tire width direction of the overlapping region Ar3 of the quarter land 3 is indicated as Ar3, then Ar2>Ar3> Ar1. Although the length is used here, it is preferable to specify the length as a ratio to the maximum width of the land. That is, the ratio of the WD in the tire width direction of the overlapping region Ar2 of the center land 2 to the maximum width W21 of the center land 2 (Ar2 / W21) is the tire width direction of the overlapping region Ar1 of the shoulder land 1 with respect to the maximum width W11 of the shoulder land 1. It is preferably larger than the ratio of WD (Ar1 / W11). In this embodiment, (Ar2 / W21)> (Ar3 / W31)> (Ar1 / W11).
In heavy-duty tires, the contact pressure is high near the tire equator TE, and traction by the slits 21 and 22 is likely to be effective, so the overlapping region Ar2 is relatively large. Since the shoulder region, which is the end region of the WD in the tire width direction, is a region where uneven wear is likely to occur, the overlapping region Ar1 is made relatively small. By making such a magnitude relationship, it is possible to suppress uneven wear while improving the effect of traction.

<Position of slits>
As shown in FIGS. 1 and 2, the tire PT sandwiches the main groove 61 closest to the tire equator TE and is adjacent to each other on the first land (quarter land 3) and the second land on the second side (quarter land 3). Center land 2) and the third land (shoulder land 1) on the first side and the fourth land (quarter land 3) on the second side that sandwich the main groove 62 on the outermost side in the tire width direction WD and are adjacent to each other. Have.

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 in the tire width direction WD. The slits 32 and 21 are misaligned with the CD in the tire circumferential direction. 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 by 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) overlap each other at least partially in the tire width direction WD. The positions of the CDs in the tire circumferential direction of the slits 12 and 31 correspond to each other.
As shown in FIG. 2, when a virtual line V2 that passes through the opening ends of the slits 32 and 21 and is parallel to the tire width direction WD is drawn, it can be seen that the openings of the slits 32 and 21 do not overlap each other.
It can be seen that when the virtual line V2 that passes through the opening ends of the slits 12 and 31 and is parallel to the tire width direction WD is drawn, the openings of the slits 12 and 31 overlap each other at least partially.

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 misaligned with the CD in the tire circumferential direction.
Further, V1 of the center line of the second slit 12 of the third land (shoulder land 1) is in the first slit 31 of the fourth land (quarter land 3). The positions of the CDs in the tire circumferential direction of the slits 12 and 31 correspond to each other.

<Slit depth>
The depths of the slits 11, 12, 21, 22, 31 and 32 are the depths of the main grooves 61 and 62 from the viewpoint of ensuring winter performance (snow performance) and preventing uneven wear and deterioration of wear resistance performance. It is preferably 50% or more and 90% or less of the slit. This is because if the depth of the slit is shallower than 50% of the depth of the main groove, the traction property after the middle stage of wear is lowered and the winter performance is deteriorated. If the depth of the slit is deeper than 90% of the depth of the main groove, the block rigidity is lowered, which causes deterioration of wear resistance and uneven wear.

The slits 21 and 22 of the center land 2 are deeper than the slits 11 and 12 of 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, it contributes to the edge effect and the ice performance is improved. Further, it is preferable that the slits 31 and 32 of the quarter land 3 are shallower than the slits 21 and 22 of the center land 2 from the viewpoint of uneven wear resistance, but the present invention is not limited to this. If the quarter land 3 has the same role as the shoulder land 1, the slits 11 and 12 of the shoulder land 1 may have the same depth as the slits 21 and 22 of 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 notches less than 1.5 mm wide. Each land 1, 2, 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 having a wavy tread shape, and extends in the tire circumferential direction CD at the central portion in the tire width direction of each land 1, 2, and 3, and the first slits 11, 21. , 31 and the second slits 12, 22 and 32 are opened to divide the land 1, 2 and 3 into the left and right in the tire width direction WD. Therefore, in the present embodiment, from the viewpoint of suppressing the movement of the divided land and reducing uneven wear, the circumferential sipe 52 has a wavy tread shape and the shape changes along the depth direction. It is a three-dimensional sipe that includes the part to be used. 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 having a wavy tread shape, extends in the tire width direction WD, and closes within each land 1, 2, and 3.
The semi-open sipe 54 is a sipe having a wavy tread shape and extends in the tire width direction WD at the central portion in the tire circumferential direction. The semi-open sipe 54 has a first end 54a that closes within each land 1, 2, 3 and a second end 54b that opens at the land end of each land 1, 2, 3.

The closed sipe 53 and the semi-open sipe 54 have a wavy tread shape, but the tread shape is not limited to this and may be a straight line. Further, the closed sipe 53 and the semi-open sipe 54 are two-dimensional sipe whose shape does not change along the depth direction, but may be a three-dimensional sipe including a portion whose shape changes along the depth direction. ..

As shown in FIGS. 1, 2 and 4, the first sipes 15, 25, 35 of the narrow land width portions 13, 23, 33 make each land 1, 2, 3 into pseudo small blocks G1, G1. It is divided. Further, the circumferential sipe 52 divides the small block G1 into left and right small blocks in the tire width direction WD, and the semi-open sipe 54 further divides the small block into the tire circumferential CD. As a result, although it is land as a whole, a plurality of pseudo small blocks G2, G3, G4, G5 (four in the center land 2 and the quarter land 3) divided into one small block G1 in the tire circumferential direction CD. Will be formed. As a result, compared to the case of adopting the block pattern divided by the slit, the traction element or the resistance to the traction element or the resistance by the pseudo small blocks G2, G3, G4, G5 smaller than the land while suppressing the occurrence of uneven wear by the land. The skid element can be increased, and the ice performance can be improved. Nevertheless, 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 in 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 tread shape of the circumferential sipe 52 is wavy. The wall surfaces of the circumferential sipes 52 come into contact with each other, and excessive movement of the small blocks can be suppressed.

As shown in FIG. 2, the small block G6 closest to the ground contact end CE, which is divided by the circumferential sipe 52 and the land width narrowing portion 13, is easily affected by the lateral force, so all the sipe 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 sipe 15, 25, 35 and the circumferential sipe 52 is thicker than the width Ws of the semi-open sipe 54, and the width of the semi-open sipe 54. Ws is preferably 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 thick, it is possible to improve the ice performance while ensuring the rigidity of the land compared to the 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 factors of wear or uneven wear. By setting the width of the semi-open sipe 54 to an intermediate width between the open sipe (first sipe, circumferential sipe 52) and the closed sipe 53, it is possible to balance the block rigidity and the ice performance. Of course, if these viewpoints are not a problem, the widths of all sipes may be the same, and the magnitude relationship of the widths can be changed in various ways.

The depth of the sipe in the present specification is preferably 50% or more and 80% or less of the depth of the main groove. If the depth of the sipe is shallower 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 will decrease, which will cause 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 the first side WD1 of the tire width direction WD. A first slit 11 (21; 31) that opens to the land end 1a (2a; 3a) and is separated from the land end 1b (2b; 3b) of the second side WD2 in the tire width direction WD, and a second tire width direction WD. A second slit 12 (22; 32) that opens at the land end 1b (2b; 3b) of the second side WD2 and is separated from the land end 1a (2a; 3a) of the first side WD1 in the tire width direction WD, and a first. Land width narrow portion 13 (23) formed by each of the slit 11 (21; 31) and the second slit 12 (22; 32) and narrower than the maximum width W11 (W21; W31) of the land 1 (2; 3). 33), and the first slit 11 (21; 31) and the second slit 12 (22; 32) are alternately arranged in the tire circumferential direction CD, and the land width narrow portion 13 (23; 33) has one first sipe 15 (25; 35) in the central portion in the tire circumferential direction, and the first sipe 15 (25; 35) extends in the tire width direction WD 13 (23; 33). It is preferable that the tires are divided.

Since land 1 (2; 3) extends continuously in the tire circumferential direction CD, rigidity can be ensured and uneven wear can be suppressed as compared with the block. Further, the first slit 11 (21; 31) and the second slit 12 (22; 32) alternately arranged in the tire circumferential direction CD secure the traction element while maintaining the rigidity balance of the land 1 (2; 3). It will be possible. Since the slits 11 and 12 (21, 22; 31, 32) form the land width narrow portion 13 (23; 33), the land width narrow portion 13 (23; 33) forms the land width narrow portion 13 (23; 33). 22; 31, 32) are 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. Nevertheless, since the land width narrow portion 13 (23; 33) is divided by the first sipe 15 (25; 35), the land continuous with the tire circumferential CD is pseudo-divided into small block groups G1 and G1. Therefore, it is possible to increase the traction element and secure the ice performance while suppressing uneven wear as compared with the block group divided by the slit.
If the land width narrow portion 13 (23; 33) is divided by two or more sipes, the land width narrow portion 13 (23; 33) becomes easy to move due to a decrease in rigidity and causes uneven wear. On the other hand, by using one first sipe 15 (25; 35) formed in the narrow land width portion 13 (23; 33), it is possible to suppress the suppression of uneven wear.
Therefore, it is possible to achieve both improvement of ice performance by the traction element and suppression of uneven wear. Further, by suppressing uneven wear, the ground contact property of the ground contact surface is improved, and it becomes possible to improve the ice performance by the water removing action of scratching and sipes.

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

As in the present embodiment, the first slit 11 (21; 31) and the second slit 12 (22; 32) adjacent to each other in the tire circumferential direction CD are partially viewed along the tire circumferential direction CD. It is preferable to have overlapping regions Ar1 (Ar2; Ar3) that overlap each other. As a result, if the lengths of the two slits 11 and 12 are totaled, the maximum width W11 of the land 1 or more is obtained, so that the traction element can be increased and the ice performance can be improved. Further, since the slit is longer than that in the case where the overlapping region Ar1 (Ar2; Ar3) is not provided, it is possible to improve the snow performance due to the shearing force of the snow column.

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

As in this embodiment, the land 1 (2; 3) opens at the land ends 1a, 1b (2a, 2b; 3a, 3b) and together with the slits 11 (21,22; 31,32), the land width narrow portion 13 Notches 14 (24; 34) sandwiching (23; 33) are provided, and the length of the overlapping region Ar1 (Ar2; Ar3) tire width direction WD is such that the notch 14 (24; 3) opens in the main groove in each land 1 (2; 3). 24; 34) is preferably longer than the length L14 (L24; L34) of the WD in the tire width direction. As a result, traction can be effectively exhibited while suppressing the occurrence of uneven wear.

As in the present embodiment, the land 1 (2; 3) has a shoulder land 1 arranged outside the outermost main groove 62 in the tire width direction WD and a center land which is the land closest to the tire equator TE. The ratio of the tire width direction WD (Ar2 / W21) to the maximum width W21 of the overlapping region Ar2 of the center land 2 is the tire width direction WD with respect to the maximum width W11 of the overlapping region Ar1 of the shoulder land 1. It is preferably larger than the ratio (Ar1 / W11). In heavy-duty tires, the contact pressure is high near the equator TE of the tire, and traction by the slits 21 and 22 is likely to be effective. Since it is an easy-to-use region, the overlapping region Ar1 is made relatively small. By making such a magnitude relationship, it is possible to suppress uneven wear while improving the effect of traction.

As in the present embodiment, the land 1 (2; 3) has 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 main groove 61. The second land (2) adjacent to the second side WD2, the third land (1) adjacent to the first side WD1 of the second main groove 62 on the outermost side in the tire width direction WD, and the second main groove 62. They are 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). Does not overlap each other 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. It is preferable that they overlap each other at least partially. As a result, by shifting the position of the CD in the tire circumferential direction with the slits 21 and 32 in the center region near the tire equator TE where the contact pressure is high, the frequency of slits appearing in the contact patch during rolling increases, and traction by the slits increases. It is possible to effectively exert the effect. Since the ground contact pressure is lower in the shoulder area near the ground contact end CE than in the center area, by matching the positions of the CDs in the tire circumferential direction of the slits 12 and 31, the relatively long traction element can be exhibited at once, effectively snowing. It is possible to improve the performance.

As in the present embodiment, the land 1 (2; 3) has a shoulder land 1 arranged outside the outermost main groove 62 in the tire width direction WD and a center land which 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 having a high contact pressure is enhanced, and the ice performance can be improved. Further, since the slit of the shoulder land 1 is relatively shallow, uneven wear can be suppressed. Further, since the slits 21 and 22 of the center land 2 remain at the end of wear, the edge effect of the slit of the center land 2 having a high contact pressure can be ensured even at the end of wear.

As in the present 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 toward the tire circumferential CD at the center of the land 1 (2; 3) in the tire width direction, and the first slit 11 (21; 31) and the second slit 12 (22; Opening to both sides of 32), the closed sipe 53 (third sipe) extends in the tire width direction WD and closes within land 1 (2; 3), and the semi-open sipe 54 (fourth sipe) is the tire. A th-th region that extends in the tire width direction WD at the tire circumferential center portion of the region G1 separated by the land width narrow portion 13 (23; 33) adjacent to the circumferential CD and closes in the land 1 (2; 3). It is preferable to have one end 54a and a second end 54b that opens to the land end of land 1 (2; 3).
As a result, the land 1 (2; 3) is divided into small blocks in the tire width direction WD by the circumferential sipe 52 (second sipe), and the land 1 (2; 3) is divided by the semi-open sipe 54 (fourth sipe). A plurality of small blocks G2, G3, G4, and G5, which are pseudo-divided into tire circumferential CDs and divided into tire circumferential CDs (four in center land 2 and quarter land 3), are pseudo-formed. Therefore, compared to the case of adopting a block pattern divided by slits, pseudo small blocks G2, G3, which are smaller than the land, while suppressing the occurrence of uneven wear by the rib-shaped land that is continuous in the tire circumferential direction. The traction element can be increased by G4 and G5, and the ice performance can be improved. Nevertheless, the closed sipe 53 (third sipe) suppresses the decrease in land rigidity while increasing the traction element, and the semi-open sipe 54 (fourth sipe) that reduces the land rigidity is the center of the small block G1 in the tire circumferential direction. Since it is provided in the portion, it is possible to increase the traction element while maintaining the rigidity balance in the small blocks G2, G3, G4, and G5, and it is possible to improve the ice performance while suppressing the occurrence of uneven wear. ..
Although not particularly limited, it is preferable that the tread shape of the circumferential sipe 52 (second sipe) is wavy. The wall surfaces of the circumferential sipe 52 (second sipe) come into contact with each other, and excessive movement of the small blocks can be suppressed, and uneven wear due to the small blocks can be suppressed.

In the above, the circumferential sipe 52, the closed sipe 53 and the semi-open sipe 54 are applied in combination 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 sipe 52 is adopted, the land can be divided into left and right in the tire width direction to make a pseudo small block. When the semi-open sipe 54 is adopted, the rigidity in these small blocks G2, G3 (G4, G5) is divided into two small blocks G2, G3 (G4, G5) adjacent to the tire circumferential CD. It is possible to increase the traction elements while maintaining the balance, and it is possible to improve the ice performance while suppressing the occurrence of uneven wear.

As in the present embodiment, the width Wo of the first sipe 15, 25, 35 and the circumferential sipe 52 (second sipe) is thicker than the width Ws of the semi-open sipe 54 (fourth sipe), and the semi-open sipe 54 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 the ice performance and suppress the occurrence of uneven wear.

Although the embodiments of the present disclosure have been described above with reference to the drawings, it should be considered that the specific configuration is not limited to these embodiments. The scope of the present disclosure is shown not only by the description of the above-described embodiment but also by the scope of claims, and further includes all modifications within the meaning and scope equivalent to the scope of claims.

<Modification 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 adjacent center lands are arranged at positions sandwiching the middle main groove.

(2) In the present embodiment, the notch 14 (24; 34) is provided, but the notch may not be provided. In the absence of a notch, the first sipes 15, 25, 35 open into the corresponding main groove or ground end.

(3) In the present embodiment, the overlapping region is formed by the first slit and the second slit, but the overlapping region may not be present.

(4) In the present embodiment, regarding the relationship between the length of the WD in the tire width direction of the overlapping regions Ar1, Ar2, Ar3 and the lengths L14, L24, L34 of the notches 14, 24, 34 in the tire width direction, Ar1> L14, Ar2> L24, Ar3> L34, but the present invention is 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) The length of the WD in the tire width direction of the overlapping region Ar2 of the center land 2, the overlapping region Ar1 of the shoulder land 1, and the overlapping region Ar3 of the quarter land 3 is, but is not limited to, Ar2> Ar3> Ar1. For example, Ar2 ≦ Ar3 ≦ Ar1 can be adopted as long as these viewpoints do not matter.

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

(7) Regarding the set of slits, in the present embodiment, since there are four main grooves, the first landing is a set of center land 2 and quarter land 3, and the second landing is shoulder land 1. It is a set of quarter land 3, 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 with the middle main groove in between, and the pair of shoulder lands are arranged on the outer side of each center land in the tire width direction. In this case, the first landing is the center land group, and the second landing is the center land and shoulder land group.

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

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

1 ... Shoulder land (land), 2 ... Center land (land), 3 ... Quarter land (land), Ar1, Ar2, Ar3 ... Overlapping area, CD ... Tire circumference direction, WD ... Tire width direction, WD1 ... Tire width direction 1st side, WD2 ... 2nd side in the tire width direction, W11, W21, W31 ... Land maximum width, 1a, 1b, 2a, 2b, 3a, 3b ... Land end 11,21,31 ... 1st slit, 12, 22, 32 ... 2nd slit, 13, 23, 33 ... Narrow land width, 15, 25, 35 ... 1st sipe, 52 ... Circumferential sipe (2nd sipe), 53 ... Closed sipe (3rd sipe) ), 54 ... Semi-open sipe (4th sipe), 14, 24, 34 ... Notch, 61 ... 1st main groove, 62 ... 2nd main groove, 2, 3 ... 1st land, 1, 3 ... 2nd Landing

Claims (8)

With land extending in the tire circumferential direction,
The land has a first slit that opens at the land end on the first side in the tire width direction and is separated from the land end on the second side in the tire width direction, and the second slit that is separated from the land end on the first side. It has a second slit that opens to the land end on the side, and a land width narrow portion that is formed by each of the first slit and the second slit and is narrower than the maximum width of the land.
The first slit and the second slit are alternately arranged in the tire circumferential direction.
The narrow land width portion has one first sipe at the center in the circumferential direction of the tire, and the first sipe extends in the width direction of the tire to divide the narrow land width portion. The pneumatic tire according to claim 1, wherein the first slit and the second slit 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 has a notch that opens at the land end and sandwiches the narrow portion of the land together with the slit.
The pneumatic tire according to claim 2, wherein the length of the overlapping region in the tire width direction is longer than the length of the notch in the tire width direction. The land is arranged as a shoulder land arranged outside the outermost main groove in the tire width direction and a center land which is the land closest to the tire equator.
The ratio of the overlapping region of the center land to the maximum width of the center land in the tire width direction is larger than the ratio of the overlapping region of the shoulder land to the maximum width of the shoulder land in the tire width direction, claim 2 or. The pneumatic tire according to 3. The land is the first land adjacent to the first side of the first main groove closest to the equator of the tire, the second land adjacent to the second side of the first main groove, and the outermost land in the tire width direction. It is 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, respectively.
The opening of the second slit on the first land and the opening of the first slit on 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 at least partially overlapped with each other when viewed in the tire width direction, according to any one of claims 1 to 4. Pneumatic tires listed. The land is arranged as a shoulder land arranged outside the outermost main groove in the tire width direction and a center land which is the land closest to the tire equator.
The pneumatic tire according to any one of claims 1 to 5, wherein the slit on the center land is deeper than the slit on the shoulder land. The land comprises a second sipe, a third sipe, and a fourth sipe.
The second sipe extends in the tire circumferential direction at the central portion of the land in the tire width direction and opens in both the first slit and the second slit.
The third sipe extends in the tire width direction and is blocked in the land.
The fourth sipe extends in the tire width direction at the central portion of the tire circumferential direction in a region separated by the land width narrow portion adjacent to each other in the tire circumferential direction, and is closed in the land at the first end and the land end. The pneumatic tire according to any one of claims 1 to 6, which has a second end that opens into. The pneumatic tire according to claim 7, wherein the width of the second sipe is thicker than the width of the fourth sipe, and the width of the fourth sipe is thicker than the width of the third sipe.

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