tire

Abstract

To provide a tire which can improve on-snow performance, on-ice performance and braking performance with good balance.SOLUTION: A tire 1 has a tread part 2 which grounds when travelling. A block 6 of the tread part 2 is provided with a hexagonal sipe group 7 in which a plurality of linear sipe pieces 7a are arranged so as to constitute a plurality of hexagons H. The hexagonal sipe group 7 includes a first depth part 8, and a second depth part 9 of which depth in a tire radial direction is smaller than that of the first depth part 8.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a tire having a tread portion. [Background technology]

[0002] Conventionally, tires with sipes in the tread portion have been known to improve performance on snow and ice. For example, Patent Document 1 below proposes a tire with improved performance on snow and ice by providing hexagonal sipes in the inner middle blocks and axial sipes in the outer middle blocks. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-030414 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the tire of Patent Document 1 tends to have reduced rigidity due to the sipes provided over the entire inner middle block, and further improvement in braking performance has been desired.

[0005] The present disclosure has been devised in view of the above circumstances, and has as its main object to provide a tire that can improve performance on snow, performance on ice, and braking performance in a well-balanced manner. [Means for solving the problem]

[0006] The present disclosure relates to a tire having a tread portion, wherein the tread portion is provided with a group of hexagonal sipes in which a plurality of linear sipe pieces are arranged to form a plurality of hexagons, and the group of hexagonal sipes includes a first depth portion and a second depth portion that is smaller in depth in the tire radial direction than the first depth portion. [Effects of the Invention]

[0007] By having the above-described configuration, the tire of the present disclosure can improve performance on snow, performance on ice, and braking performance in a well-balanced manner. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a development view of a tread portion showing an embodiment of a tire according to the present disclosure. [Figure 2] FIG. 10 is an enlarged view of a block provided with a group of hexagonal sipes. [Figure 3] FIG. 3 is a cross-sectional perspective view schematically showing a first deep portion. [Figure 4] FIG. 4 is a cross-sectional perspective view schematically showing a second deep portion. [Figure 5] FIG. 10 is an enlarged view of a block when worn. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. FIG. 1 is a development view of a tread portion 2 showing a tire 1 of this embodiment. As shown in FIG. 1, the tire 1 of this embodiment has a tread portion 2 that comes into contact with the road surface during travel. The tire 1 can be suitably employed, for example, as a pneumatic tire for passenger cars used in winter. The tire 1 is not limited to this embodiment, and may also be employed, for example, as a heavy-duty tire, a motorcycle tire, a non-pneumatic tire that is not filled with pressurized air inside, and the like.

[0010] The tread portion 2 includes, for example, a plurality of circumferential grooves 3 extending continuously in the tire circumferential direction, land portions 4 divided by the circumferential grooves 3, and a plurality of lateral grooves 5 crossing the land portions 4 in the tire axial direction. As a result, the land portions 4 in this embodiment are divided into a plurality of blocks 6 by the circumferential grooves 3 and the lateral grooves 5.

[0011] In such a tread portion 2, the circumferential grooves 3 and the lateral grooves 5 can generate snow column shear force, and the circumferential grooves 3 and the lateral grooves 5 can also exert an edge effect. Therefore, the tread portion 2 of this embodiment is useful for improving the steering stability of the tire 1 when traveling on snowy roads (hereinafter referred to as "snow performance") and when traveling on icy roads (hereinafter referred to as "ice performance").

[0012] At least one of the blocks 6 of the tread portion 2 of this embodiment is provided with a hexagonal sipe group 7 in which a plurality of linear sipe pieces 7a are arranged to form a plurality of hexagons H. Such a tread portion 2 can achieve an edge effect and a snow-biting effect in the tire circumferential direction and the tire axial direction, thereby improving the performance of the tire 1 on snow and ice.

[0013] Here, in this specification, a sipe is a cut having a width of 2 mm or less perpendicular to the longitudinal direction. Furthermore, in this specification, unless otherwise specified, the dimensions of each part of the tire 1 are values ​​measured in a normal state. In the case where the tire 1 is a pneumatic tire, the "normal state" refers to a state in which the tire 1 is mounted on a normal rim, adjusted to a normal internal pressure, and no load is applied.

[0014] A "genuine rim" is a rim that is specified for each tire in a standard system that includes the standard on which tire 1 is based, such as a "standard rim" for JATMA, a "design rim" for TRA, or a "measuring rim" for ETRTO. If there is no standard system that includes the standard on which tire 1 is based, a "genuine rim" is a rim that is specified for each tire by the manufacturer, etc.

[0015] "Normal internal pressure" is the air pressure specified for each tire by the standard system, including the standard on which tire 1 is based. For JATMA, it is the "maximum air pressure," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is the "INFLATION PRESSURE." If there is no standard system including the standard on which tire 1 is based, "normal internal pressure" is the air pressure specified for each tire by the manufacturer, etc.

[0016] In this embodiment, an example is shown in which the hexagonal sipe group 7 is provided in the block 6 closest to the tread end Te, but this is not limited to such an example, and the hexagonal sipe group 7 may be provided in other land portions 4.

[0017] Here, in the case where the tire 1 is a pneumatic tire, the tread edge Te is the axially outermost contact point when the tire 1 in a normal state is loaded with a normal load and contacts a flat surface with a camber angle of 0°. The tire equator C is the axial center position between a pair of tread edges Te.

[0018] "Normal load" is the load determined for each tire by the standard system including the standard on which tire 1 is based, and is the "maximum load capacity" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "LOAD CAPACITY" for ETRTO. "Normal load" is the load determined for each tire by the manufacturer, etc., when there is no standard system including the standard on which tire 1 is based.

[0019] Fig. 2 is an enlarged view of a block 6 provided with a hexagonal sipe group 7. As shown in Fig. 2, the hexagonal sipe group 7 of this embodiment includes a first deep portion 8 and a second deep portion 9 that is deeper in the tire radial direction than the first deep portion 8. In Fig. 2, for ease of understanding, the first deep portion 8 is represented by a thicker line than the second deep portion 9.

[0020] Such hexagonal sipe groups 7 can maintain high rigidity and improve the braking performance on dry roads of the tire 1. Therefore, the tire 1 of this embodiment can improve the performance on snow, performance on ice, and braking performance in a well-balanced manner.

[0021] More preferably, the hexagonal sipe group 7 includes a first hexagon H1 and a second hexagon H2 adjacent to each other as the multiple hexagons H. The multiple sipe pieces 7a in this embodiment include one first sipe piece 7b constituting the first hexagon H1, one second sipe piece 7c constituting the second hexagon H2, and a third sipe piece 7d connecting the first sipe piece 7b and the second sipe piece 7c. It is desirable that the first sipe piece 7b and the second sipe piece 7c extend parallel to each other. The first sipe piece 7b and the second sipe piece 7c extend, for example, in the tire axial direction.

[0022] In this embodiment, the first deep portion 8 is formed in a crank shape by the first sipe piece 7b, the second sipe piece 7c, and the third sipe piece 7d. In this type of hexagonal sipe group 7, the first deep portion 8 is bent in a crank shape, which prevents the rigidity of the block 6 from being excessively reduced, and can provide an edge effect in the tire circumferential direction and the tire axial direction. Note that the first deep portion 8 is not limited to this embodiment, and may be, for example, a portion of the sipe piece 7a that is deeper.

[0023] It is desirable that a plurality of first deep portions 8 are arranged spaced apart in the tire circumferential direction. In this embodiment, a pair of first deep portions 8 adjacent in the tire circumferential direction have their cranks oriented in opposite directions. In such first deep portions 8, adjacent first deep portions 8 in the tire circumferential direction are arranged with a positional offset in the tire axial direction, which suppresses a decrease in the rigidity of the block 6 in the tire circumferential direction and improves the braking performance of the tire 1.

[0024] 3 is a cross-sectional perspective view schematically illustrating the first deep portion 8. As shown in FIG. 3, the first deep portion 8 of this embodiment includes at least one bent portion 8a that bends in the direction of the sipe width w1 in the tire radial direction. When a large external force acts on the block 6, such as during braking, the bent portions 8a support each other in the first deep portion 8, thereby preventing a decrease in rigidity. Note that the bent portion 8a may have a three-dimensional shape, such as a so-called Miura folding structure.

[0025] The sipe width w1 of the bent portion 8a is preferably 0.5 mm or less. Such bent portion 8a can reliably support the blocks 6 when a large external force acts on them, such as during braking, thereby improving the braking performance of the tire 1. From this perspective, the sipe width w1 of the bent portion 8a is more preferably 0.3 mm or less.

[0026] The first deep portion 8 preferably includes a straight portion 8b that extends linearly radially inward of the bent portion 8a in the tire radial direction. Such straight portion 8b can provide edge effect and snow-biting effect even after the bent portion 8a has disappeared due to wear or the like, and can maintain the performance on snow and ice of the tire 1 for a long period of time.

[0027] In this embodiment, the sipe width w2 of the straight portion 8b is larger than the sipe width w1 of the bent portion 8a. Since the sipe width w2 of such straight portion 8b increases when the tire wears, the snow column shear force can be increased, and the on-snow performance of the tire 1 when worn can be improved.

[0028] The sipe width w2 of the straight portion 8b is preferably 1.0 mm or less. Such straight portion 8b prevents the rigidity of the block 6 from being excessively reduced, and can improve the on-snow performance, on-ice performance, and braking performance of the tire 1 in a well-balanced manner when worn. From this perspective, the sipe width w2 of the straight portion 8b is more preferably 0.7 mm or less.

[0029] The depth d2 of the bent portions 8a is preferably 10% to 50% of the depth d1 of the first deep portion 8. By making the depth d2 of the bent portions 8a 10% or more of the depth d1 of the first deep portion 8, the straight portions 8b are prevented from becoming excessively large, and the bent portions 8a can reliably exhibit their mutual support effect, thereby suppressing a decrease in rigidity. By making the depth d2 of the bent portions 8a 50% or less of the depth d1 of the first deep portion 8, the straight portions 8b with a large sipe width w2 are reliably present when wear has progressed to the point where the second deep portion 9 has disappeared, which helps to improve the on-snow performance of the tire 1 over a long period of time.

[0030] 4 is a cross-sectional perspective view schematically showing the second deep portion 9. As shown in Fig. 4, the second deep portion 9 of this embodiment extends linearly in the tire radial direction. Such a second deep portion 9 has a high snow compaction effect and can improve snow column shear force.

[0031] The sipe width w3 of the second deep portion 9 is preferably 0.5 mm or less. Such a second deep portion 9 can achieve an edge effect and a water absorption effect due to capillary action, thereby improving the on-ice performance of the tire 1. From this perspective, the sipe width w3 of the second deep portion 9 is more preferably 0.3 mm or less.

[0032] As shown in Figures 3 and 4, it is desirable that the sipe width w3 of the second deep portion 9 be approximately equal to the sipe width w1 of the bent portion 8a. Here, in this specification, "approximately equal" means that the difference in dimensions is within ±15%. Such second deep portion 9, in cooperation with the bent portion 8a, can achieve a balanced edge effect and snow-engaging effect in the tire circumferential and axial directions.

[0033] The depth d3 of the second deep portion 9 is preferably 10% to 50% of the depth d1 of the first deep portion 8. When the depth d3 of the second deep portion 9 is 10% or more of the depth d1 of the first deep portion 8, it is possible to prevent the second deep portion 9 from disappearing in the early stage of wear. When the depth d3 of the second deep portion 9 is 50% or less of the depth d1 of the first deep portion 8, it is possible to prevent the rigidity of the block 6 from decreasing excessively.

[0034] It is desirable that the depth d3 of the second deep portion 9 be approximately equal to the depth d2 of the bent portion 8a. In such a hexagonal sipe group 7, when the second deep portion 9 disappears due to wear, the straight portion 8b with the large sipe width w2 of the first deep portion 8 appears, thereby improving the on-snow performance, on-ice performance, and braking performance of the tire 1 for a long period of time.

[0035] Fig. 5 is an enlarged view of a block 6 when worn. As shown in Fig. 5, when the block 6 of this embodiment wears, the straight line portions 8b of the first deep portions 8 appear and the second deep portions 9 disappear. In such a block 6, when worn, the first deep portions 8 adjacent in the tire circumferential direction are arranged with a displacement in the tire axial direction, which suppresses a decrease in the rigidity of the block 6 in the tire circumferential direction and improves the braking performance of the tire 1 when worn.

[0036] Although particularly preferred embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above-described embodiments and can be modified and implemented in various forms.

[0037] [Note] The present disclosure is as follows.

[0038] [Disclosure 1] A tire having a tread portion, wherein the tread portion is provided with a group of hexagonal sipes in which a plurality of linear sipe pieces are arranged to form a plurality of hexagons, and the group of hexagonal sipes includes a first depth portion and a second depth portion that is smaller in depth in the tire radial direction than the first depth portion.

[0039] [Disclosure 2] The tire described in Disclosure 1, wherein the hexagonal sipe group includes a first hexagon and a second hexagon adjacent to each other as the plurality of hexagons, the plurality of sipe pieces include one first sipe piece constituting the first hexagon, one second sipe piece constituting the second hexagon, and a third sipe piece connecting the first sipe piece and the second sipe piece, and the first depth portion is formed in a crank shape by the first sipe piece, the second sipe piece, and the third sipe piece.

[0040] [Disclosure 3] The tire described in Disclosure 2, wherein the first deep portions are arranged in a plurality of positions spaced apart in the tire circumferential direction, and a pair of the first deep portions adjacent in the tire circumferential direction have crank orientations in opposite directions.

[0041] [Disclosure 4] The tire according to any one of Disclosures 1 to 3, wherein the depth of the second deep portion is 10% to 50% of the depth of the first deep portion.

[0042] [Disclosure 5] The tire according to any one of disclosures 1 to 4, wherein the first depth portion includes at least one bent portion that bends in a direction perpendicular to the longitudinal direction of the sipe piece in the tire radial direction.

[0043] [Disclosure 6] The tire according to Disclosure 5, wherein the first depth portion includes a straight portion that extends straight in the tire radial direction and more inward than the bent portion in the tire radial direction.

[0044] [Disclosure 7] 7. The tire according to claim 6, wherein a sipe width in the straight portion is greater than a sipe width in the curved portion.

[0045] [Disclosure 8] The tire according to any one of Disclosures 1 to 7, wherein the second depth portion extends linearly in the tire radial direction. [Explanation of symbols]

[0046] 1 tire 2 Tread section 6 blocks 7 Hexagonal sipe group 7a sipe piece 8 First depth section 9 Second Depth

Claims

1. A tire having a tread portion, The tread portion is provided with a group of hexagonal sipes in which a plurality of linear sipe pieces are arranged to form a plurality of hexagons, The group of hexagonal sipes includes a first depth portion and a second depth portion that is smaller in depth in the tire radial direction than the first depth portion, The hexagonal sipe group includes, as the plurality of hexagons, a first hexagon and a second hexagon adjacent to each other, the plurality of sipe pieces include one first sipe piece constituting the first hexagon, one second sipe piece constituting the second hexagon, and a third sipe piece connecting the first sipe piece and the second sipe piece, The first depth portion is formed in a crank shape by the first sipe piece, the second sipe piece, and the third sipe piece. tire.

2. The first depth portion is a plurality of first depth portions arranged spaced apart in the tire circumferential direction, The tire according to claim 1 , wherein a pair of the first depth portions adjacent in the tire circumferential direction have crank directions opposite to each other.

3. A tire having a tread portion, The tread portion is provided with a group of hexagonal sipes in which a plurality of linear sipe pieces are arranged to form a plurality of hexagons, The group of hexagonal sipes includes a first depth portion and a second depth portion that is smaller in depth in the tire radial direction than the first depth portion, The first depth portion includes at least one bent portion that bends in a direction perpendicular to the longitudinal direction of the sipe piece in the tire radial direction. tire.

4. The tire according to claim 3 , wherein the first depth portion includes a linear portion that extends linearly radially inward of the bent portion in the tire radial direction.

5. The tire according to claim 4 , wherein a sipe width in the straight portion is greater than a sipe width in the bent portion.

6. 6. The tire according to claim 1, wherein the depth of the second depth portion is 10% to 50% of the depth of the first depth portion.

7. The tire according to claim 1 , wherein the second depth portion extends linearly in the tire radial direction.

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