CN115107419B - pneumatic tire - Google Patents

Abstract

The present invention provides a pneumatic tire, wherein a plurality of 1 st pattern blocks respectively comprise: the circumferential slit open at both the 1 st block end and the 2 nd block end, the 1 st circumferential sipe open at the 1 st block end and closed in the land portion, and the 2 nd circumferential sipe open at the 2 nd block end and closed in the land portion. The plurality of axial slits each have: the 1 st intersection, which is the intersection between the circumferential slit and the axial slit that open at the 1 st block end, and the 2 nd intersection, which is the intersection between the circumferential slit and the axial slit that open at the 2 nd block end. The 1 st intersection and the 2 nd intersection at the same axial slit are different from each other in position in the tire axial direction. The circumferential slit and the 2 nd circumferential sipe of the 1 st block adjacent to the 1 st side face each other with the axial slit interposed therebetween, and the circumferential slit and the 1 st circumferential sipe of the 1 st block adjacent to the 2 nd side face each other with the axial slit interposed therebetween.

Description

Pneumatic tire

Technical Field

The present invention relates to a pneumatic tire.

Background

Pneumatic tires, particularly those for heavy loads mounted on trucks, buses, and the like, are required to have uneven wear resistance as described in japanese patent application laid-open No. 2019-108122. In addition, a tire capable of being mounted on a rear wheel as a driving wheel is required to have traction performance. Tires capable of being mounted on front wheels as steering wheels are required to have lateral slip resistance.

Disclosure of Invention

The present invention provides a method of: a pneumatic tire capable of ensuring traction performance, uneven wear resistance and lateral sliding resistance.

The pneumatic tire of the present invention includes a land portion extending along a tire circumferential direction, the land portion having: a plurality of axial slits each open at least any one of land portion ends on both sides in a tire axial direction, and a plurality of 1 st blocks arranged in the tire circumferential direction, the plurality of 1 st blocks each having: a1 st block end disposed on a1 st side in a tire circumferential direction, a2 nd block end disposed on a2 nd side opposite to the 1 st side in the tire circumferential direction, a circumferential slit extending in the tire circumferential direction and opening at both the 1 st block end and the 2 nd block end, a1 st circumferential sipe extending in the tire circumferential direction and opening at the 1 st block end and closing in the land portion, and a2 nd circumferential sipe extending in the tire circumferential direction and opening at the 2 nd block end and closing in the land portion, the plurality of axial slits each having: a1 st intersection, which is an intersection point between the circumferential slit and the axial slit, which are open at the 1 st block end, and a2 nd intersection, which is an intersection point between the circumferential slit and the axial slit, which are open at the 2 nd block end, the positions of the 1 st intersection and the 2 nd intersection at the same axial slit in the tire axial direction are different from each other, the circumferential slit and the 2 nd circumferential sipe of the 1 st block adjacent to the 1 st side face each other with the axial slit interposed therebetween, and the circumferential slit and the 1 st circumferential sipe of the 1 st block adjacent to the 2 nd side face each other with the axial slit interposed therebetween.

Drawings

Fig. 1 is a developed view showing an example of the tread surface of the pneumatic tire of the present invention.

Fig. 2 is an enlarged expanded view showing the center land portion of embodiment 1.

Fig. 3 is an enlarged expanded view showing the center land portion of embodiment 1.

Fig. 4 is an enlarged expanded view showing the center land portion of embodiment 1.

Fig. 5 is a perspective view of the tread surface of embodiment 1 as seen obliquely from above.

Fig. 6 is a sectional view of each portion shown in fig. 1 and 4.

Fig. 7 is an expanded view showing an example of the tread surface of modification 1 of embodiment 1.

Fig. 8 is an expanded view showing an example of the tread surface of modification 2 of embodiment 1.

Fig. 9 is an expanded view showing an example of the tread surface of modification 3 of embodiment 1.

Fig. 10 is an expanded view showing an example of the tread surface of modification 4 of embodiment 1.

Description of the reference numerals

1. 2 … central land portion (land portion); 4a, 4b … land portions; 4c … block 1 end; 4d … block 2 end; 40 … axial slit; 40a … part 1; 40b … part 2; 40c …, 3 rd position; 41 … circumferential slits; 42 … 1 st circumferential sipe; 43 … 2 nd circumferential sipe; 44 … intersection 1; 45 … intersection 2; AD … tire axial direction; AD3 … side 3; AD4 … side 4; b1 … block 1; b2 … block 2; CD … tire circumferential direction; CD1 … side 1; CD2 … side 2.

Detailed Description

[ embodiment 1 ]

Next, embodiment 1 of the present invention 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 simply referred to as "tire PT") according to embodiment 1. Fig. 2 to 4 are partial enlarged views of the center land portion 1 shown in fig. 1. Fig. 5 is a perspective view of the tread surface of the pneumatic tire of embodiment 1, viewed obliquely from above. FIG. 6 is a cross-sectional view of the A1-A1 site shown in FIG. 1, the A2-A2 site, the A3-A3 site and the A4-A4 site shown in FIG. 4. The vertical direction of fig. 1 to 5 corresponds to the tire circumferential direction CD, and the horizontal direction of fig. 1 to 5 corresponds to the tire axial direction AD. The figure shows the shape of the tread portion when the tire is new. As shown in fig. 1 and 5, the pneumatic tire PT includes: a plurality of land portions 1, 2, 3 extending along the tire circumferential direction CD. The tire PT of embodiment 1 is a heavy load tire mounted on a truck, bus, or the like. Of course, the tire of the present specification is not limited to this, and may be used for a small truck. However, the present invention is not applicable to tires for passenger vehicles. In the case of JATMA, the term "small truck tire" means: the description is given in chapter B: tire for small truck, the heavy load tire means: chapter "C: described in truck and bus chapter "or" D: a tire for a building vehicle.

The tread surface Tr (ground contact surface contacting the road surface) of the tire PT is provided with: 3 main grooves 61, 62, 61 extending continuously along the tire circumferential direction CD. In embodiment 1, the number of main grooves is 3, but the present invention is not limited thereto. The number of the main grooves can be more than 3. Embodiment 1 includes: the tire shoulder main groove 61 located on the outermost side in the tire axial direction AD, and the center main groove 62 disposed on the inner side of the tire axial direction AD of the tire shoulder main groove 61 and closest to the tire equatorial plane TE. Although the main groove is not particularly limited, it may be configured, for example, as follows: has a groove width of 3% or more of the distance (dimension in the tire axial direction AD) between the land ends LE, LE. Although the main groove is not particularly limited, it may be configured, for example, as follows: has a groove width of 7.0mm or more. Although the main groove is not particularly limited, it may be configured, for example, as follows: continuous in the tire circumferential direction CD, the groove is deepest in the tread surface Tr, and a TWI (tread wear indicator) indicating the use limit of wear is provided in the groove.

In the present specification, slit means: a groove having a narrower width than the main groove, but a wider width than the sipe. The slit includes: the axial slit 40 and the circumferential slit 41 described later. Sipe means: a groove having a width of 1.5mm or less. The sipe includes: the 1 st circumferential sipe 42 and the 2 nd circumferential sipe 43 described later.

The ground contact end LE is the outermost end of the tread surface Tr (ground contact surface) in the tire axial direction AD. The tread surface Tr (ground contact surface) means: in a state where the tire is mounted on a regular rim and filled with a regular internal pressure, a surface of the tire that contacts the road surface when a regular load is applied thereto is placed perpendicularly to the flat road surface. The normal rim is: in a specification system including a specification according to which a tire is mounted, a rim is determined for each tire according to the specification. If JATMA, it is "standard rim", and if TRA or ETRTO, it is "measuring rim".

The normal internal pressure is: in a specification system including specifications according to which tires are based, the air pressure determined for each tire is the highest air pressure in the case of JATMA, and the maximum value described in the table "tire load limit under various cold inflation pressures" in the case of TRA, and is the "inflation pressure" in the case of ETRTO.

The normal load is: in a specification system including specifications according to which tires are based, a load is determined for each tire according to each specification. In the case of JATMA, the maximum load capacity is the maximum value described in the above table in the case of TRA, and the load capacity is the maximum value in the case of ETRTO.

< shoulder land portion 3 >)

As shown in fig. 1 and 5, the tire PT has, at both ends in the tire axial direction AD of the tread surface Tr: a shoulder land portion 3 extending along the tire circumferential direction CD. The shoulder land portion 3 is divided by the shoulder main groove 61 and the ground contact end LE. The shoulder land portions 3 extend continuously in the tire circumferential direction CD. The shoulder land portion 3 has: a groove extending along the tire axial direction AD and opening to the ground contact end LE at the shoulder main groove 61 and breaking the shoulder land portion 3.

< center land portion 1, 2 >)

As shown in fig. 1 and 5, the tire PT has at least 1 center land portion 1, 2 between the pair of shoulder main grooves 61, 61. The central land portions 1, 2 are the land portions closest to the tire equatorial plane TE. The center land portions 1 and 2 of embodiment 1 are partitioned by a center main groove 62 and shoulder main grooves 61. The center land portions 1, 2 extend along the tire circumferential direction CD, respectively. In embodiment 1, the center land portion 1 is disposed in: is located further to the 3 rd side AD3 (left side in the drawing) of the tire axial direction AD than the tire equatorial plane TE. The center land portion 2 is disposed: the tire is positioned further toward a4 th side AD4 (right side in the drawing) opposite to the 3 rd side AD3 than the tire equatorial plane TE in the tire axial direction AD. Hereinafter, the center land portion 1 is sometimes referred to as a1 st land portion, and the center land portion 2 is sometimes referred to as a2 nd land portion. The center land portion 2 (2 nd land portion) has the same shape as the center 1 (1 st land portion), and the center land portion 2 is: the center land portion 1 is made to slide along the tire axial direction AD and the positions of the land portions in the tire circumferential direction CD are made to be different. The center land portion 1 will be mainly described, and a detailed description thereof will be omitted with respect to the center land portion 2.

< axial slit 40 >)

As shown in fig. 1, 2 and 5, the center land portion 1 includes: a plurality of axial slits 40, and a plurality of 1 st blocks B1 (see fig. 2) arranged in the tire circumferential direction CD. The axial slit 40 may be open at least one of the land portion ends 4a, 4b on both sides in the tire axial direction AD. Accordingly, since the axial slit 40 is opened at least in one of the main grooves 61, 62 on both sides, the traction performance can be ensured. The axial slit 40 in embodiment 1 is open at the land portion end 4a on the 3 rd side AD3 of the tire axial direction AD and open at the land portion end 4b on the 4 th side AD4 of the tire axial direction AD. Accordingly, the plurality of axial slits 40 divide the center land portion 1 into a plurality of 1 st blocks B1 (see fig. 2). The axial slit 40 is shallower than either of the main grooves 61, 62. Accordingly, the land portion rigidity of the center land portion 1 can be ensured, and the wear resistance and uneven wear resistance can be ensured. Specifically, as shown in fig. 6, the depth D2 of the axial slit 40 in the tire radial direction RD is: the depth D1 of the main grooves 61, 62 is 10% or more and 40% or less. The depth is the depth of the tire radial direction RD, but the description of the tire radial direction RD is omitted later.

Block 1, block 1 end 4c, block 2 end >

As shown in fig. 2, the 1 st blocks B1 of the center land portion 1 each have: the 1 st block end 4c, the 2 nd block end 4d, the circumferential slit 41 extending along the tire circumferential direction CD, the 1 st circumferential sipe 42 extending along the tire circumferential direction CD, and the 2 nd circumferential sipe 43 extending along the tire circumferential direction CD. The 1 st block end 4c is arranged on the 1 st side CD1 in the tire circumferential direction of the 1 st block B1. The 2 nd block end 4d is arranged on the 2 nd side CD2 in the tire circumferential direction of the 1 st block B1. The 2 nd side CD2 in the tire circumferential direction is the opposite side of the 1 st side CD1 in the tire circumferential direction. The 1 st block end 4c is formed by the axial slit 40. The 2 nd block end 4d is formed by the axial slit 40.

< circumferential slit 41 >)

As shown in fig. 1, 2 and 5, the circumferential slit 41 opens at both ends of the 1 st block end 4c and the 2 nd block end 4 d. In embodiment 1, the circumferential slit 41 is inclined with respect to both the tire circumferential direction CD and the tire axial direction AD, and is formed in a straight line in a plan view (in a case of viewing in a line of sight parallel to the tire radial direction). The circumferential slit 41 is shallower than the main grooves 61, 62. Accordingly, the land portion rigidity of the center land portion 1 can be ensured, and the wear resistance and uneven wear resistance can be ensured. Specifically, as shown in fig. 6, the depth D2 of the circumferential slit 41 is: the depth D1 of the main grooves 61, 62 is 10% or more and 40% or less. In embodiment 1, the depth D2 of the circumferential slit 41 is the same as the depth D2 of the axial slit 40, but the present invention is not limited thereto.

< 1 st intersection 44, 2 nd intersection 45 >

As shown in fig. 2 and 3, the plurality of axial slits 40 each include: the 1 st intersection 44 and the 2 nd intersection 45, which are different from each other in the tire axial direction AD, are located. The 1 st intersection 44 is: the intersection between the opening of the circumferential slit 41 at the 1 st block end 4c and the axial slit 40. The 1 st intersection 44 is disposed: the position closer to the 4 th side AD4 (right side in the drawing) of the tire axial direction AD than the 2 nd intersection 45. The 2 nd intersection 45 is: the intersection between the opening of the circumferential slit 41 at the 2 nd block end 4d facing the 1 st block end 4c and the axial slit 40. Accordingly, the opening of the circumferential slit 41 disposed on the 1 st side CD1 of the tire circumferential direction CD with the axial slit 40 interposed therebetween and the opening of the circumferential slit 41 disposed on the 2 nd side CD2 of the tire circumferential direction CD are disposed so as to be offset from each other in the tire axial direction AD. The respective circumferential slits 41 are avoided from being continuously connected in the tire circumferential direction CD, so that the land portion rigidity can be improved.

< 1 st circumferential sipe 42, 2 nd circumferential sipe 43 >

As shown in fig. 1, 2, 3 and 5, the 1 st circumferential sipe 42 is open at the 1 st block end 4c and closed in the land portion. That is, although one end of the 1 st circumferential sipe 42 is open at the 1 st block end 4c, the other end is not open at any of the axial slit 40, the circumferential slit 41, and the main grooves 61, 62. The 2 nd circumferential sipe 43 is open at the 2 nd block end 4d and closed in the land portion. That is, although one end of the 2 nd circumferential sipe 43 is open at the 2 nd block end 4d, the other end is not open at any of the axial slit 40, the circumferential slit 41, and the main grooves 61, 62. In embodiment 1, the 1 st circumferential sipe 42 and the 2 nd circumferential sipe 43 are linear in plan view, but may be wavy. The 1 st circumferential sipe 42 is not connected to the 2 nd circumferential sipe 43. If the 1 st circumferential sipe 42 and the 2 nd circumferential sipe 43 are linear in a plan view, the sipe is easier to open than if it is in a wave shape, and the lateral sliding resistance can be improved. If the 1 st circumferential sipe 42 and the 2 nd circumferential sipe 43 have a waveform shape in a plan view, the movement of the land portion (1 st block B1) can be suppressed as compared with the case of being linear, and the uneven wear resistance can be improved.

As shown in fig. 3, the length L42 of the 1 st circumferential sipe 42 in the tire circumferential direction CD is preferably: the length L41 of the circumferential slit 41 in the tire circumferential direction CD is 20% or more and 50% or less. The length L43 of the 2 nd circumferential sipe 43 in the tire circumferential direction CD is preferably: the length L41 of the circumferential slit 41 in the tire circumferential direction CD is 20% or more and 50% or less. This is because: the rigidity of the 1 st block B1 can be ensured, and the wear resistance and the uneven wear resistance can be improved.

As shown in fig. 6, the depth D3 of the 1 st circumferential sipe 42 and the 2 nd circumferential sipe 43 is preferably: the depth D1 of the main grooves 61, 62 is 10% or more and 50% or less. Accordingly, the block rigidity can be ensured, and the wear resistance and uneven wear resistance can be improved. In embodiment 1, the depth D3 of the 1 st circumferential sipe 42 and the 2 nd circumferential sipe 43 is the same as the depth D2 of the axial slit 40 and the circumferential slit 41, but the present invention is not limited thereto.

< positional relationship of circumferential sipe and circumferential slit >)

As shown in fig. 3, the 1 st blocks B11, B12, B13 are arranged from the 1 st side CD1 toward the 2 nd side CD2 of the tire circumferential direction CD. The circumferential slit 41 of the 1 st block B12 and the 2 nd circumferential sipe 43 of the 1 st block B11 adjacent to the 1 st side CD1 face each other with the axial slit 40 interposed therebetween. The circumferential slit 41 of the 1 st block B12 and the 1 st circumferential sipe 42 of the 1 st block B13 adjacent to the 2 nd side CD2 face each other with the axial slit 40 interposed therebetween.

Here, the so-called "facing" may be: an extension line V1 of the center line of the circumferential sipes 42, 43 enters the axial slit 40. In addition, the so-called "facing" may be: in the case where an imaginary line V2 passing through the circumferential sipes 42 and 43 and the open ends of the axial slit 40 and parallel to the tire circumferential direction CD is drawn, the opening of the circumferential sipe 42 or 43 and the opening of the axial slit 40 overlap each other at least partially.

As shown in fig. 2, in embodiment 1, among the 1 st blocks B1, the 1 st circumferential sipe 42 is disposed on the 3 rd side AD3 (left side in the drawing) of the tire axial direction AD of the circumferential slit 41, and the 2 nd circumferential sipe 43 is disposed on the 4 th side AD4 (right side in the drawing) of the tire axial direction AD of the circumferential slit 41. In each 1 st block B1, the 1 st circumferential sipe 42 and the 2 nd circumferential sipe 43 are arranged in: the circumferential slit 41 is sandwiched from both sides in the tire axial direction AD. Accordingly, the rigidity balance in the 1 st block B1 exhibits good, so that the uneven wear resistance is improved.

As shown in fig. 2, the axial slit 40 is inclined with respect to both the tire axial direction AD and the tire circumferential direction CD. The axial slit 40 is curved at the 1 st intersection 44 and the 2 nd intersection 45, and has 2 bending points (the 1 st intersection 44 and the 2 nd intersection 45). The portions between the bending points in the axial slit 40 and the portions from the bending points to the land end are respectively formed in a straight line shape. Accordingly, the axial slit 40 has: 3 straight parts and 2 bending points (44, 45) connecting the adjacent 2 straight parts. By providing the axial slit 40 with a bending point in this way, the axial slit 40 can be provided with a component extending along the tire circumferential direction CD, and the lateral sliding resistance can be ensured. On the other hand, although the 1 st block B1 is easily movable due to the axial slit 40, by providing a bending point, excessive movement of the 1 st block B1 can be suppressed. As a result, uneven wear resistance can be improved.

As shown in fig. 2, at the 1 st intersection 44, which is a bending point of the axial slit 40, the 2 nd circumferential sipe 43 opens into the axial slit 40, and the circumferential slit 41 opens into the axial slit 40. In addition, at the 2 nd intersection 45, which is a bending point of the axial slit 40, the 1 st circumferential sipe 42 opens in the axial slit 40, and the circumferential slit 41 opens in the axial slit 40. Accordingly, the circumferential slit 41 and the circumferential sipes 42 and 43 are opened at the bending points of the axial slit 40, whereby the circumferential slit 41 and the circumferential sipes 42 and 43 can be effectively opened, and traction performance and lateral sliding resistance can be improved.

As shown in fig. 3, the 1 st block end 4c is formed in a convex shape (mountain) at the 2 nd intersection 45 in a plan view, and the 1 st circumferential sipe 42 opens into the axial slit 40. Accordingly, any one corner among the corners (1 st corner) of the 2 land portions formed between the 1 st circumferential sipe 42 and the axial slit 40 is liable to generate an acute angle θ1. On the other hand, at the 2 nd intersection 45 where the 2 nd block end 4d appears concave (valley) in plan view, the circumferential slit 41 facing the 1 st circumferential sipe 42 opens in the axial slit 40. Accordingly, any one corner among the corners (2 nd corner) of the 2 land portions formed between the circumferential slit 41 and the axial slit 40 is liable to generate an obtuse angle θ2. Although uneven wear tends to occur at the 1 st corner and the 2 nd corner, uneven wear tends to occur at the 2 nd corner as compared with the 1 st corner because the land portion formed by the circumferential slit 41 having a larger groove width than the circumferential sipes 42 and 43 tends to move. Accordingly, compared to a configuration in which the circumferential slit 41 opens at the axial slit 40 at the intersection where the block end appears in a convex shape (fig. 8), a configuration in which the circumferential slit 41 opens at the axial slit at the intersection where the block end appears in a concave shape is likely to be an obtuse angle due to the corner between the circumferential slit 41 and the axial slit 40, and therefore, uneven wear resistance can be improved.

The same applies to the 1 st intersection 44. Specifically, the 2 nd circumferential sipe 43 opens into the axial slit 40 at the 1 st intersection 44 where the 2 nd block end 4d appears in a convex shape in plan view. At the 1 st intersection 44 where the 1 st block end 4c is formed in a concave shape in plan view, the circumferential slit 41 facing the 2 nd circumferential sipe 43 opens in the axial slit 40. In addition, the sum of the angles of the 2 nd corners may be greater than: the sum of the angles of the 2 1 st corner portions facing the 2 nd corner portions.

Relationship between center land portion 1 (1 st land portion) and center land portion 2 (2 nd land portion)

As shown in fig. 1, the center land portion 1 (1 st land portion) and the center land portion 2 (2 nd land portion) are different in position in the tire circumferential direction CD. Specifically, the axial slit 40 of the 2 nd land portion (2) and the axial slit 40 of the 1 st land portion (1) do not overlap each other when viewed along the tire axial direction AD (viewed in a line of sight parallel to the tire axial direction AD). That is, when the axial slit 40 of the 2 nd land portion (2) and the axial slit 40 of the 1 st land portion (1) are projected parallel to the tire axial direction AD with the tire equatorial plane TE as a projection plane, the axial slit 40 of the 2 nd land portion (2) and the axial slit 40 of the 1 st land portion (1) do not overlap each other.

The 1 st circumferential sipe 42 and the 2 nd circumferential sipe 43 of the 1 st land portion (1) and the axial slit 40 of the 2 nd land portion (2) do not overlap each other when viewed in the tire axial direction AD.

Accordingly, since the traction elements (the 1 st circumferential sipe 42, the 2 nd circumferential sipe 43, and the axial slit 40) are dispersedly present in the range of contact with the road surface, traction performance and lateral slip resistance can be exhibited when the tire rotates.

< sipe 46 >

As shown in fig. 4 to 6, each of the circumferential slit 41 and the axial slit 40 includes: a base sipe 46 is open at a portion of the bottom surface of the slit. In fig. 4, the base sipe 46 is shown in phantom. Accordingly, the block rigidity can be ensured by the sipe having a bottom 46, and the traction performance and the lateral sliding resistance in the mid-wear period can be improved, as compared with the configuration in which only the slits 40 and 41 are formed. As shown in fig. 6, the maximum depth D4 obtained by adding the slits 40, 41 and the sipe 46 is preferably: the depth D1 of the main grooves 61, 62 is 40% or more and 90% or less. Accordingly, the traction performance in the mid-wear period and the lateral sliding resistance can be improved. As shown in fig. 5, the bottom sipe 46 of the circumferential slit 41 is: the shape in which the shallowest shallow bottom portion 46a is provided at the center portion in the sipe length direction and the deepest deep bottom portions 46b are provided at both sides of the shallow bottom portion 46a in the sipe length direction is not limited thereto. The depth of the base sipe 46 of the axial slit 40 is constant except for the end.

As shown in fig. 4 and 5, the plurality of axial slits 40 each include: a1 st portion 40a from the land portion end 4b of the 4 th side AD4 (right side in the drawing) to the 1 st intersection 44, a2 nd portion 40b from the 1 st intersection 44 to the 2 nd intersection 45, and a3 rd portion 40c from the 2 nd intersection 45 to the land portion end 4a of the 3 rd side AD3 (left side in the drawing). The sipe 46 is formed in the 1 st portion 40a and the 3 rd portion 40c. On the other hand, the sipe 46 is not formed in the 2 nd portion 40b. The 1 st portion 40a, 3 rd portion 40c, and circumferential slit 41 having the bottom sipe 46 are configured to: the shape of the Z is Z-shaped when seen from the top. Accordingly, the sipe 46 is not formed in the 2 nd portion 40b of the center portion in the tire axial direction AD of the center land portion 1, so that the land portion rigidity can be improved, and the wear resistance and uneven wear resistance can be improved. Further, by arranging the base sipe 46 in a zigzag shape, traction performance and lateral sliding resistance by the base sipe 46 can be ensured. Further, since the 2 1 st blocks B11 and B12 divided by the axial slit 40 are connected to the 2 nd portion 40B in the tire circumferential direction CD to form the 2 nd block B2 which is virtual to join the 1 st blocks B11 and B12, the blocks virtually lengthen in the tire circumferential direction CD, the tire circumferential rigidity (front-rear rigidity) of the center land portion 1 can be ensured, and the uneven wear resistance can be improved.

The sipe 46 having a bottom portion disposed at the 1 st portion 40a or 3 rd portion 40c of the axial slit 40 is formed as: one end is open in the main groove 61 or the main groove 62, and the other end is closed in the land portion. The sipe 46 disposed in the circumferential slit 41 is closed in the land portion.

The length of the sipe 46 formed in the circumferential slit 41 in the tire circumferential direction CD is preferably: the length L41 of the circumferential slit 41 in the tire circumferential direction CD is 80% or more and 100% or less.

The total length of the sipe formed in the axial slit 40 in the tire axial direction AD of the sipe 46 is preferably: the length of the axial slit 40 in the tire axial direction AD is 50% or more and 70% or less. The length of the sipe formed in the 1 st portion 40a in the tire axial direction AD of the sipe 46 is preferably: the length of the 1 st part 40a in the tire axial direction AD is 70% or more and 90% or less. The length of the sipe formed in the 3 rd position 40c in the tire axial direction AD of the sipe 46 is preferably: the 3 rd portion 40c has a length of 70% to 90% of the tire axial direction AD.

As shown in fig. 4, the center land portion 1 has: a plurality of 1 st blocks B1 (B11, B12) divided in the tire circumferential direction CD by the axial slit 40, and a plurality of 2 nd blocks B2 divided in the tire circumferential direction CD by the 1 st portion having the sipe base, the 3 rd portion, and the circumferential slit 41. The length LB2 of the tire circumferential direction CD of the 2 nd block B2 is longer than: length LB1 of tire circumferential direction CD of 1 st block B1. Accordingly, the tire circumferential rigidity (front-rear rigidity) of the center land portion 1 can be ensured, and the uneven wear resistance can be improved.

Modification example

(1) Fig. 7 shows a tread surface of modification 1 of embodiment 1. As shown in fig. 7, the axial slit 40 may be linear in plan view, and may not have a curved portion and may not be curved. In embodiment 1 shown in fig. 1 to 6, the axial slit 40 includes: the straight portions are connected at the bending points, but the straight portions may be curved. In modification 1 of fig. 7, the arrangement of the sipe 46 is the same as that of embodiment 1 shown in fig. 1 to 6.

(2) In embodiment 1 shown in fig. 3, the axial slit 40 is bent at the intersections 44 and 45, and the circumferential slit 41 is opened at the intersections 44 and 45 having a concave shape (valley) in a plan view, but the present invention is not limited to this. For example, as shown in fig. 8. Fig. 8 shows a tread surface of modification 2 of embodiment 1. As shown in fig. 8, the circumferential slit 41 may be opened in the axial slit 40 at the intersections 44 and 45 having a convex shape (mountain) in a plan view, and the circumferential sipes 42 and 43 may be opened in the axial slit 40 at the intersections 44 and 45 having a concave shape (valley) in a plan view. With this configuration, the circumferential slit 41 and the circumferential sipes 42 and 43 are opened at the bending points of the axial slit 40, and thus the circumferential slit 41 and the circumferential sipes 42 and 43 can be effectively opened, and traction performance and lateral sliding resistance can be improved. However, as shown in fig. 8, the angle of the corner of the 2 land portions formed between the circumferential slit 41 and the axial slit 40 is an acute angle θ1, and the uneven wear resistance is slightly lower than that of the configuration shown in fig. 3.

In the modification 2 of fig. 8, the arrangement of the sipe 46 is not shown, but is the same as that of embodiment 1 shown in fig. 1 to 6.

(3) In embodiment 1 shown in fig. 1 to 5, the plurality of axial slits 40 are open at both land portion ends 4a, 4b on both sides in the tire axial direction AD, but the present invention is not limited thereto. For example, as shown in fig. 9. Fig. 9 shows a tread surface of modification 3 of embodiment 1. As shown in fig. 9, the plurality of axial slits 40 are open at only one of the land portion ends 4a, 4b on both sides in the tire axial direction AD. In the example shown in fig. 9, the axial slit 40 includes: the 1 st axial slit which is open at the land portion end 4a of the 3 rd side AD3 of the tire axial direction AD and which is closed in the land portion by being separated from the land portion end 4b of the 4 th side AD4, and the 2 nd axial slit which is open at the land portion end 4b of the 4 th side AD4 and which is closed in the land portion by being separated from the land portion end 4a of the 3 rd side AD 3. As shown in fig. 9, the 1 st axial slit and the 2 nd axial slit are alternately arranged along the tire circumferential direction CD. In this case, the length of the axial slit 40 in the tire axial direction is preferably: the length of the tire axial direction AD of the center land portion 1 (land portion) is 60% or more. Accordingly, the plurality of axial slits 40 divide the land portion into a plurality of virtual 1 st blocks B1 in the tire circumferential direction CD.

(4) In embodiment 1, the circumferential slit 41 is inclined with respect to both the tire circumferential direction CD and the tire axial direction AD, but is not limited thereto. For example, as shown in fig. 10, the circumferential slit 41 may be parallel to the tire circumferential direction CD. Fig. 10 shows a tread surface of modification 4 of embodiment 1.

In embodiment 1, the circumferential slit 41 is sandwiched between the 1 st circumferential sipe 42 and the 2 nd circumferential sipe 43 in each 1 st block in the tire axial direction AD, but the present invention is not limited thereto. For example, as shown in fig. 10, in each 1 st block, the 1 st circumferential sipe 42 and the 2 nd circumferential sipe 43 may be disposed in only one of the tire axial directions AD of the circumferential slit 41.

(5) In embodiment 1, a plurality (2) of center land portions 1, 2 are provided so as to sandwich the tire equatorial plane TE, but 1 may be provided.

(6) The tire PT of the embodiment shown in fig. 1 to 10 includes: a tread pattern symmetrical about a point on the tire equatorial plane TE. However, this is not a limitation. For example, the tire PT may have: a tread pattern that is symmetric in the right-left direction about the tire equatorial plane TE, a tread pattern that is asymmetric in the right-left direction, or a tread pattern that specifies the direction of rotation of the tire.

As described above, the pneumatic tire PT may include, as in embodiment 1 shown in fig. 1 to 6 and the modifications shown in fig. 7 to 10: land portions 1, 2 extending along the tire circumferential direction CD, the land portions 1, 2 having: the plurality of axial slits 40 and the plurality of 1 st blocks B1 arranged in the tire circumferential direction CD, the plurality of axial slits 40 are open at least one of land portion ends 4a, 4B on both sides in the tire axial direction AD, and the plurality of 1 st blocks B1 each have: a1 st block end 4c arranged on a1 st side CD1 of the tire circumferential direction CD, a2 nd block end 4d arranged on a2 nd side CD2 opposite to the 1 st side CD1 of the tire circumferential direction CD, circumferential slits 41 extending along the tire circumferential direction CD and opening at both the 1 st block end 4c and the 2 nd block end 4d, a1 st circumferential sipe 42 extending along the tire circumferential direction CD and opening at the 1 st block end 4c and closing in the land portion, and a2 nd circumferential sipe 43 extending along the tire circumferential direction CD and opening at the 2 nd block end 4d and closing in the land portion, the plurality of axial slits 40 each having: the 1 st intersection 44, which is the intersection between the circumferential slit 41 and the axial slit 40 where the 1 st block end 4c opens, and the 2 nd intersection 45, which is the intersection between the circumferential slit 41 and the axial slit 40 where the 2 nd block end 4d opens, are located at different positions in the tire axial direction AD between the 1 st intersection 44 and the 2 nd intersection 45 in the same axial slit 40, and the circumferential slit 41 and the 2 nd circumferential sipe 43 of the 1 st block adjacent to the 1 st side CD1 face each other with the axial slit 40 interposed therebetween, and the circumferential slit 41 and the 1 st circumferential sipe 42 of the 1 st block adjacent to the 2 nd side CD2 face each other with the axial slit 40 interposed therebetween.

According to this configuration, the traction performance can be ensured by the axial slit 40 opening at the land portion end, and the lateral sliding resistance against the lateral force in the tire axial direction AD can be improved by the circumferential slit 41 and the circumferential sipes 42 and 43 extending along the tire circumferential direction CD. Further, the circumferential slits 41 and the circumferential sipes 42 and 43 are alternately arranged along the tire circumferential direction throughout the plurality of 1 st blocks B1, and the opening positions of the circumferential slits 41 are different, whereby the situation in which the respective circumferential slits 41 are continuously connected in the tire circumferential direction CD is avoided, and therefore, the rigidity balance of the blocks can be ensured, and the uneven wear resistance can be improved.

As in the embodiments shown in fig. 1 to 9, the configuration may be such that: in each 1 st block B1, the 1 st circumferential sipe 42 is disposed on the 3 rd side AD3 of the tire axial direction AD of the circumferential slit 41, and the 2 nd circumferential sipe 43 is disposed on the 4 th side AD4 of the tire axial direction AD of the circumferential slit 41 opposite to the 3 rd side AD 3.

According to this configuration, the 1 st circumferential sipe 42 and the 2 nd circumferential sipe 43 are arranged in: since the circumferential slit 41 is sandwiched between both sides in the tire axial direction AD, rigidity in one block is well balanced, and uneven wear resistance can be further improved.

As in the embodiments shown in fig. 1 to 10, the lengths L42, L43 of the 1 st circumferential sipe 42 and the 2 nd circumferential sipe 43 in the tire circumferential direction CD may be 20% to 50% of the length of the circumferential slit 41 in the tire circumferential direction CD.

With this configuration, the block rigidity can be ensured, and the wear resistance and uneven wear resistance can be improved.

As in the embodiment shown in fig. 1 to 10, the circumferential slit 41 and the axial slit 40 may each include: a base sipe 46 is open at a portion of the bottom surface of the slit.

With this configuration, the block rigidity can be ensured, and the traction performance in the mid-wear period and the lateral sliding resistance can be improved.

As in the embodiments shown in fig. 1 to 8, the configuration may be such that: the plurality of axial slits 40 are open at land portion ends 4a, 4b of both the 3 rd side AD3 of the tire axial direction AD and the land portion end 4b of the 4 th side AD4 opposite to the 3 rd side AD3 of the tire axial direction AD, respectively, and in each of the plurality of axial slits 40, the 1 st intersection 44 is disposed closer to the 4 th side AD4 than the 2 nd intersection 45, and the plurality of axial slits 40 each have: the sipe 46 is formed in the 1 st portion 40a and the 3 rd portion 40c from the land portion end 4b of the 4 th side AD4 to the 1 st intersection 44, the 2 nd portion 40b from the 1 st intersection 44 to the 2 nd intersection 45, and the 3 rd portion 40c from the 2 nd intersection 45 to the land portion end 4a of the 3 rd side AD3, but is not formed in the 2 nd portion 40b.

According to this configuration, the 2 nd portion 40b is the tire axial direction center portion of the land portion, and rigidity of this portion can be improved, and wear resistance and uneven wear resistance can be improved. Further, the 1 st portion 40a, 3 rd portion 40c, and circumferential slit 41 having the bottom sipe 46 are configured to: the 1 st block B1 divided by the axial slit 40 is connected in the tire circumferential direction CD by the 2 nd portion 40B so that the 1 st block B1 becomes longer in the tire circumferential direction CD, and therefore, the front-rear rigidity (rigidity of the tire circumferential direction CD) of the land portion can be ensured, and the uneven wear resistance can be improved.

As in the embodiment shown in fig. 4, the configuration may be as follows: the land portion 1 has a plurality of 2 nd blocks B2, the plurality of 1 st blocks B1 are each divided in the tire circumferential direction CD by the axial slit 40, the plurality of 2 nd blocks B2 are each divided in the tire circumferential direction CD by the 1 st portion 40a having the sipe 46, the 3 rd portion 40c, and the circumferential slit 41, and the length LB2 of the 2 nd blocks B2 in the tire circumferential direction CD is longer than: length of the 1 st block B1 in the tire circumferential direction CD.

With this configuration, the front-rear rigidity (rigidity in the tire circumferential direction CD) of the land portion can be ensured, and the uneven wear resistance can be further improved.

As in the embodiments shown in fig. 1 to 6 and 8 to 10, the configuration may be as follows: the plurality of axial slits 40 are curved at the 1 st intersection 44 and the 2 nd intersection 45, respectively, the 1 st circumferential sipe 42 opens at the 2 nd intersection 45, the 2 nd circumferential sipe 43 opens at the 1 st intersection 44, and the axial slits 40.

According to this configuration, by opening the circumferential sipes 42, 43 and the circumferential slit 41 at the bending points 44, 45 of the axial slit 40, the grooves (the circumferential sipes 42, 43 and the circumferential slit 41) can be effectively formed, and traction and lateral sliding resistance can be improved.

As in the embodiments shown in fig. 1 to 6, 9, and 10, the configuration may be as follows: the 1 st circumferential sipe 42 and the 2 nd circumferential sipe 43 are open in the axial slit 40 at intersecting portions 44, 45 where the block ends are convex in plan view, and the circumferential slit 41 is open in the axial slit 40 at intersecting portions 44, 45 where the block ends are concave in plan view.

According to this configuration, the angle of the corner portion between the circumferential slit 41 and the axial slit 40 can be made to be the obtuse angle θ2, and the uneven wear resistance at the corner portion can be improved as compared with a configuration in which the block end exhibits a mountain shape in a plan view of the circumferential slit 41 and the intersection portion is opened (fig. 8).

As in the embodiment shown in fig. 1 to 8 and 10, the plurality of axial slits 40 may be open at the land portion ends 4a and 4b on both sides in the tire axial direction AD.

With this configuration, the axial slit 40 can ensure traction performance.

As in the embodiment shown in fig. 1 or 5, the land portions 1 and 2 may include: the 1 st land portion 1 disposed closer to the 3 rd side AD3 of the tire axial direction AD than the tire equatorial plane TE and the 2 nd land portion 2 disposed closer to the 4 th side AD4 opposite to the 3 rd side AD3 of the tire axial direction AD than the tire equatorial plane TE, and the 1 st circumferential sipe 42 and the 2 nd circumferential sipe 43 of the 1 st land portion 1 and the axial slit 40 of the 2 nd land portion 2 do not overlap each other when viewed along the tire axial direction AD.

According to this configuration, since the circumferential sipes 42 and 43 of the 1 st land portion 1 and the axial slits 40 of the 2 nd land portion 2 are arranged so as to be dispersed in the tire circumferential direction CD, at least one of the circumferential sipes 42 and 43 of the 1 st land portion 1 and the axial slits 40 of the 2 nd land portion 2 is likely to appear in the ground contact surface when the tire rolls, and therefore, traction performance and lateral slip resistance can be effectively exhibited.

Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments. The scope of the present invention is defined by the claims rather than by the description of the embodiments described above, and includes all modifications within the meaning and scope equivalent to the scope of the claims.

The configuration used in each of the above embodiments may be used in any other embodiment. The specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention.

The configuration used in each of the above embodiments may be used in any other embodiment.

Claims (10)

1. A pneumatic tire having a land portion extending in a tire circumferential direction, characterized in that,

the land portion has: a plurality of axial slits, and a plurality of 1 st blocks arranged in the tire circumferential direction,

the plurality of axial slits are open at least any one of land portion ends on both sides in the tire axial direction,

the plurality of 1 st blocks each have: a1 st block end disposed on a1 st side in a tire circumferential direction, a2 nd block end disposed on a2 nd side opposite to the 1 st side in the tire circumferential direction, a circumferential slit extending in the tire circumferential direction and opening at both the 1 st block end and the 2 nd block end, a1 st circumferential sipe extending in the tire circumferential direction and opening at the 1 st block end and closing in the land portion, and a2 nd circumferential sipe extending in the tire circumferential direction and opening at the 2 nd block end and closing in the land portion,

the plurality of axial slits each have: a1 st intersection, which is an intersection point between the circumferential slit and the axial slit that are open at the 1 st block end, and a2 nd intersection, which is an intersection point between the circumferential slit and the axial slit that are open at the 2 nd block end,

the 1 st intersection and the 2 nd intersection at the same axial slit are different from each other in position in the tire axial direction,

the circumferential slit and the 2 nd circumferential sipe of the 1 st block adjacent to the 1 st side face each other with the axial slit interposed therebetween,

the circumferential slit and the 1 st circumferential sipe of the 1 st block adjacent to the 2 nd side face each other with the axial slit interposed therebetween.

2. A pneumatic tire according to claim 1, wherein,

in each of the 1 st blocks, the 1 st circumferential sipe is disposed on a3 rd side in the tire axial direction of the circumferential slit, and the 2 nd circumferential sipe is disposed on a4 th side opposite to the 3 rd side in the tire axial direction of the circumferential slit.

3. A pneumatic tire according to claim 2, wherein,

the length of the 1 st circumferential sipe in the tire circumferential direction of the 2 nd circumferential sipe is: the length of the circumferential slit in the tire circumferential direction is 20% or more and 50% or less.

4. A pneumatic tire according to any one of claim 1 to 3, wherein,

the circumferential slit and the axial slit each have: a portion of the bottom surface of the slit is provided with an open bottom sipe.

5. A pneumatic tire according to claim 4, wherein,

the plurality of axial slits are open at both the land portion end on the 3 rd side in the tire axial direction and the land portion end on the 4 th side opposite to the 3 rd side in the tire axial direction,

in each of the plurality of axial slits, the 1 st intersection is disposed further toward the 4 th side than the 2 nd intersection,

the plurality of axial slits each have: a1 st part from the land part end on the 4 th side to the 1 st intersection, a2 nd part from the 1 st intersection to the 2 nd intersection, and a3 rd part from the 2 nd intersection to the land part end on the 3 rd side,

the sipe having a bottom is formed in the 1 st portion and the 3 rd portion, but is not formed in the 2 nd portion.

6. A pneumatic tire according to claim 5, wherein,

the land portion has: a plurality of the 2 nd block is provided,

the plurality of 1 st blocks are divided in the tire circumferential direction by the axial slits respectively,

the plurality of 2 nd blocks are divided in the tire circumferential direction by the 1 st portion having the sipe base, the 3 rd portion, and the circumferential slit respectively,

the length of the tire circumferential direction of the 2 nd block is longer than: length in the tire circumferential direction of the 1 st block.

7. A pneumatic tire according to any one of claim 1 to 3, wherein,

the plurality of axial slits are curved at the 1 st intersection and the 2 nd intersection, respectively,

the 1 st circumferential sipe is open at the axial slit at the 2 nd intersection,

the 2 nd circumferential sipe is open at the axial slit at the 1 st intersection.

8. A pneumatic tire as in claim 7, wherein,

the 1 st circumferential sipe and the 2 nd circumferential sipe are open at the axial slit at intersections where block ends appear convex in a plan view,

the circumferential slit is open at the axial slit at a crossing portion where the block end is concave in plan view.

9. A pneumatic tire according to any one of claim 1 to 3, wherein,

the plurality of axial slits are open at land portion ends on both sides in the tire axial direction, respectively.

10. A pneumatic tire according to any one of claim 1 to 3, wherein,

the land portion includes: a1 st land portion disposed on a3 rd side in the tire axial direction from the tire equatorial plane, and a2 nd land portion disposed on a4 th side opposite to the 3 rd side in the tire axial direction from the tire equatorial plane,

the 1 st circumferential sipe and the 2 nd circumferential sipe of the 1 st land portion and the axial slit of the 2 nd land portion do not overlap each other when viewed in the tire axial direction.