tire

Abstract

To provide a tire that can further improve snow performance and wet performance. [Solution] The tire has a tread portion comprising: a plurality of widthwise grooves extending in the direction along the tire width direction and connected to the tire contact edge, spaced apart in the circumferential direction of the tire; a plurality of circumferential grooves extending in the direction along the circumferential direction and connected to each other; a plurality of shoulder land portions partitioned by the plurality of widthwise grooves and circumferential grooves; and a connecting portion formed in a part of the plurality of shoulder land portions, connecting the widthwise groove on the footing side and the widthwise groove on the push-off side. The connecting portion is formed of a plurality of narrow grooves having a groove width that gradually increases from the tread surface toward the groove bottom, and has an intersection where the plurality of narrow grooves intersect, a footing-side connecting portion connecting the intersection with the widthwise groove on the footing side, and a push-off-side connecting portion connecting the intersection with the widthwise groove on the push-off side. The push-off-side connecting portion has two narrow grooves that are inclined toward opposite sides with respect to the circumferential direction with respect to the intersection centered on the intersection.

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] Generally, winter tires prioritize snow performance and wet performance. For example, when the hardness of the tire compound is low, the adhesion between the tread surface and the road surface increases, improving snow performance. On the other hand, when the hardness of the tire compound is low, the block rigidity also decreases, resulting in a decline in wet performance.

[0003] Citation Document 1 discloses a tire capable of suppressing a decline in wet performance by providing a wide groove having a widened portion with a groove width increasing toward the groove bottom in the shoulder land portion.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In winter tires, further improvement in snow performance and wet performance is required.

[0006] An object of the present invention is to provide a tire capable of further improving snow performance and wet performance.

Means for Solving the Problems

[0007] A tire according to one aspect of the present invention is a tire provided with a tread portion having a tread surface and having a designated rotational direction, wherein, in the tread portion, Multiple widthwise grooves extending in the direction along the tire width and connecting to the tire contact edge, provided at intervals in the circumferential direction of the tire, Multiple circumferential grooves extending in a direction along the circumferential direction of the tire and connecting to each other in the width direction grooves, Multiple shoulder land portions are provided outside the tire width direction from the multiple circumferential grooves, and are partitioned by the multiple widthwise grooves and the multiple circumferential grooves. The system includes a connecting portion formed in at least a portion of the aforementioned multiple shoulder land portions, which connects the widthwise groove on the stepping side and the widthwise groove on the kicking side that demarcate the shoulder land portion, The connecting portion is formed of a plurality of narrow grooves having a groove width that gradually increases from the tread surface toward the groove bottom, and includes an intersection where the plurality of narrow grooves intersect, a foot-side connecting portion that connects the intersection with the widthwise groove on the foot-stepping side, and a kick-off side connecting portion that connects the intersection with the widthwise groove on the kick-off side. The kick-out side connection portion has two narrow grooves that are inclined in opposite directions with respect to the tire circumferential direction, with respect to the intersection portion as the center. [Effects of the Invention]

[0008] According to the present invention, snow performance and wet performance can be further improved. [Brief explanation of the drawing]

[0009] [Figure 1] This is a partial plan view of the tire according to this embodiment. [Figure 2] This is a partial end view of the tire according to this embodiment, along the line II-II shown in Figure 1. [Figure 3] This is a partial cross-sectional view of the tire according to this embodiment, along the line III-III shown in Figure 1. [Figure 4] This is a partially enlarged view of the tire according to this embodiment, along the line IV-IV shown in Figure 1. [Figure 5] This is a partially enlarged view of the tire according to this embodiment, along the VV line shown in Figure 1. [Modes for carrying out the invention]

[0010] Embodiments of the present invention relate to the following aspects.

[0011] [Aspect 1] A tire having a tread portion with a tread surface, and having a specified direction of rotation, In the tread portion, Multiple widthwise grooves extending in the direction along the tire width and connecting to the tire contact edge, provided at intervals in the circumferential direction of the tire, Multiple circumferential grooves extending in a direction along the circumferential direction of the tire and connecting to each other in the width direction grooves, Multiple shoulder land portions are provided outside the tire width direction from the multiple circumferential grooves, and are partitioned by the multiple widthwise grooves and the multiple circumferential grooves. The system includes a connecting portion formed in at least a portion of the aforementioned multiple shoulder land portions, which connects the widthwise groove on the stepping side and the widthwise groove on the kicking side that demarcate the shoulder land portion, The connecting portion is formed of a plurality of narrow grooves having a groove width that gradually increases from the tread surface toward the groove bottom, and includes an intersection where the plurality of narrow grooves intersect, a foot-side connecting portion that connects the intersection with the widthwise groove on the foot-stepping side, and a kick-off side connecting portion that connects the intersection with the widthwise groove on the kick-off side. The kick-off side connection portion has two narrow grooves that are inclined in opposite directions relative to the tire circumferential direction, with respect to the intersection portion as the center. [Aspect 2] The tire according to embodiment 1, wherein the groove depth of the plurality of narrow grooves gradually increases from the stepping side to the kicking side. [Aspect 3] The tire according to embodiment 1, wherein the distance Xc in the tire width direction between the tire contact end and the intersection and the distance Pa in the tire width direction between the tire contact end of the shoulder land portion and the tire width direction edge of the shoulder land portion satisfy the following equation (1). Pa × 0.4 ≤ Xc ≤ Pa × 0.6 ···(1) [Aspect 4] The angle formed between the two narrow grooves in the kicking-side connecting portion is 60 degrees or more and 90 degrees or less. The tire according to aspect 1. [Aspect 5] The stepping-in side connecting portion has two narrow grooves that are inclined in opposite directions with respect to the tire circumferential direction around the intersection portion. The angle formed between the two narrow grooves in the kicking-side connecting portion is 30 degrees or more and 90 degrees or less. The tire according to aspect 1. [Aspect 6] For the plurality of narrow grooves, the groove width Wsgu on the tread surface, the groove bottom width Wsgl at the groove bottom, and the groove width Wg of the widthwise groove that demarcates the stepping-in side of the shoulder land portion satisfy the relationship of the following formula (2). The tire according to aspect 1. Wg×0.4≦Wsgu<Wsgl≦Wg×0.8···(2) [Aspect 7] For the plurality of narrow grooves, the groove depth Dsgf on the stepping-in side, the groove depth Dsgr on the kicking-out side, and the groove depth Dg of the widthwise groove that demarcates the stepping-in side of the shoulder land portion satisfy the relationship of the following formula (3). The tire according to aspect 1. Dg×0.6≦Dsgf<Dsgr≦Dg×1.0···(3)

[0012] (Definition) The tire radial direction refers to the direction orthogonal to the tire rotation axis. The tire radial direction inner side refers to the side facing the tire rotation axis in the tire radial direction, and the tire radial direction outer side refers to the side away from the tire rotation axis in the tire radial direction. The tire circumferential direction refers to the circumferential direction with the tire rotation axis as the central axis. The tire width direction refers to the direction parallel to the tire rotation axis. The tire width direction inner side refers to the side facing the tire equatorial plane (tire equator line) in the tire width direction, and the tire width direction outer side refers to the side away from the tire equatorial plane in the tire width direction. The tire equatorial plane refers to the plane that is orthogonal to the tire rotation axis and passes through the center of the tire width of the tire. "Following" a certain standard includes being aligned in a direction less than ±35° from that standard. "Center" includes the midpoint where the distance from two points is equal, and a range of ±10% of the distance between the two points from the midpoint. The groove width is measured as the maximum distance between opposing groove walls at the groove opening on the tread surface when the tire is mounted on a standard rim and filled to the standard internal pressure in an unloaded state. In the case of a configuration with a notch or chamfer at the groove opening, the groove width is the value measured with the endpoint being the intersection of the extension line of the tread surface and the extension line of the groove wall in a cross-sectional view parallel to the groove width direction and groove depth direction. Groove depth is measured as the maximum distance from the tread surface to the bottom of the groove when the tire is mounted on a standard rim, filled to the standard internal pressure, and under no load. If the groove in question has partial irregularities or sipes at the bottom of the groove, the groove depth shall be the value measured excluding these irregularities or sipes. The contact end is the maximum position in the tire width direction at the contact surface between the tire and the flat plate when the tire is mounted on a regular rim, subjected to regular internal pressure, and placed perpendicular to the flat plate in a stationary state, with a load corresponding to the regular load (80% of the maximum load capacity) applied. Similarly, in the following explanation, "regular rim" refers to the "applicable rim" as defined by JATMA, the "Design Rim" as defined by TRA, or the "Measuring Rim" as defined by ETRTO. Similarly, in the following explanation, "normal internal pressure" refers to the "maximum air pressure" specified by JATMA, the maximum value listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or "INFLATION PRESSURES" specified by ETRTO. Furthermore, "normal load" refers to the "maximum load capacity" specified by JATMA, the maximum value listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or "LOAD CAPACITY" specified by ETRTO.

[0013] (Overall structure) Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Figure 1 is a partial plan view of the tire 10, which is mounted on a regular rim, subjected to regular internal pressure, and placed perpendicular to a flat plate in a stationary state, with a load corresponding to a regular load (80% of the maximum load capacity) applied to it.

[0014] The tire 10 shown in Figure 1 has a tread portion 12 on the radially outer side of the tire. The tire 10 has a specified direction of rotation. The tire 10 is equipped with a rotation direction indicator (not shown) that indicates the direction of tire rotation. The tire rotation direction refers to the direction of rotation that is most frequently used when the tire is in use, for example, the direction of rotation when the vehicle is moving forward. Based on the indication of this rotation direction indicator, the tread side (the side that touches first or the heel side) and the push-off side (the side that touches last or the toe side) of the tread block are defined (see Figure 1). The rotation direction indicator is, for example, made up of marks or indentations on the sidewall of the tire 10. In Figure 1, the lower side is the tread side. In Figure 1, the upper side is the push-off side.

[0015] The tread portion 12 is formed of rubber material (tread rubber). The tread portion 12 has a tread surface 14 that contacts the road surface when the vehicle is running. The tread surface 14 is annular in shape with respect to the rotation axis of the tire 10, has a predetermined length in the tire width direction, and is continuous in the tire circumferential direction. A tread pattern of a predetermined pattern is engraved on the tread surface 14. The tread pattern is asymmetrical with respect to the tire equatorial plane CP between the two sides in the tire width direction of the tire equatorial plane CP. In Figure 1, the symbol EL indicates the contact edge line (a line connecting continuous tire contact edges E in the tire circumferential direction).

[0016] The tread rubber is formed from a rubber material with excellent contact characteristics and weather resistance, and is exposed on the tread surface 14. Preferably, the tread rubber contains silica, wax, and an anti-aging agent.

[0017] The tire 10 has a tread surface 14 equipped with a widthwise groove 16, a circumferential groove 18, a shoulder land portion 20, and a connecting portion 22.

[0018] The widthwise grooves 16 are provided on both sides in the tire width direction with respect to the tire equatorial plane CP. Multiple widthwise grooves 16 are provided at predetermined intervals in the tire circumferential direction. The groove width of the widthwise grooves 16 may be, for example, 2.0 mm to 8.0 mm. The groove depth of the widthwise grooves 16 may be, for example, 6.0 mm to 9.0 mm.

[0019] The tire 10 shown in Figure 1 shows three of the multiple widthwise grooves 16 arranged on both sides in the tire width direction relative to the tire equatorial plane CP. Specifically, in Figure 1, from the stepping side to the push-off side, the first left widthwise groove 24, second left widthwise groove 26, and third left widthwise groove 28 are shown on one side relative to the tire equatorial plane CP, and the first right widthwise groove 30, second right widthwise groove 32, and third right widthwise groove 34 are shown on the other side relative to the tire equatorial plane CP. The widthwise grooves 16 extend in a direction along the tire width direction, and the outer side in the tire width direction is connected to the tire contact edge E.

[0020] The inner side of the widthwise groove 16 in the tire width direction is connected to the inclined groove 36. The inclined groove 36 extends from the inner end of the widthwise groove 16 in the tire width direction toward the inner side in the tire width direction, in a direction that slopes from the kicking side toward the stepping side. The inclined grooves 36, provided on both sides in the tire width direction, form a roughly V shape in plan view and intersect each other on the inner side in the tire width direction. The inclined groove 36 has a tapered shape in which the groove width gradually decreases from the outer end in the tire width direction toward the inner tip in the tire width direction.

[0021] The circumferential grooves 18 are provided on both sides in the tire width direction with respect to the tire equatorial plane CP, at positions between the tire equatorial plane CP and the tire contact edge E. The circumferential grooves 18 extend in a direction along the tire circumferential direction and are connected to two adjacent widthwise grooves 16 in the tire circumferential direction. The foot-in side of the circumferential groove 18 may be connected to the connection portion between the widthwise groove 16 and the inclined groove 36. The kick-out side of the circumferential groove 18 may be connected to the inclined groove 36. The groove width of the circumferential groove 18 may be, for example, 2.0 mm to 5.0 mm. The groove depth of the circumferential groove 18 may be, for example, 4.0 mm to 7.0 mm.

[0022] The shoulder land area 20 is divided by two adjacent widthwise grooves 16 and a circumferential groove 18 in the tire circumferential direction. That is, the tire 10 has shoulder land areas 20 on both sides in the tire width direction with respect to the tire equatorial plane CP, and multiple shoulder land areas 20 are provided at predetermined intervals in the tire circumferential direction. Figure 1 shows the first left shoulder land area 38, divided by the first left widthwise groove 24, the second left widthwise groove 26 and the circumferential groove 18; the second left shoulder land area 40, divided by the second left widthwise groove 26, the third left widthwise groove 28 and the circumferential groove 18; the first right shoulder land area 42, divided by the first right widthwise groove 30, the second right widthwise groove 32 and the circumferential groove 18; and the second right shoulder land area 44, divided by the second right widthwise groove 32, the third right widthwise groove 34 and the circumferential groove 18. Focusing on the first left shoulder track section 38, the widthwise groove 16 on the stepping side is the first left widthwise groove 24, and the widthwise groove 16 on the push-off side is the second left widthwise groove 26.

[0023] The connecting portion 22 is formed on at least a portion of the multiple shoulder land portions 20. The connecting portion 22 connects the widthwise grooves 16 on the stepping side and kicking side that demarcate the shoulder land portion 20. Preferably, the connecting portion 22 is provided on 50% or more of the multiple shoulder land portions 20 provided in the circumferential direction of the tire, more preferably on 75% or more, and even more preferably on 85% or more. Preferably, the shoulder land portions 20 having the connecting portion 22 are evenly arranged in the circumferential direction of the tire.

[0024] The connecting portion 22 is formed by a plurality of narrow grooves 46. As shown in Figure 2, each narrow groove 46 has a pair of groove walls 48 and a groove bottom 50 connected to the inner ends of the groove walls 48 in the tire radial direction. The distance between the groove walls of the narrow groove 46 gradually increases from the tread surface 14 toward the groove bottom 50. That is, the pair of groove walls 48 are inclined in a direction in which the distance between the groove walls widens from the tread surface 14 toward the groove bottom 50.

[0025] When the groove width, which is the distance between the groove walls at the groove opening 52 on the tread surface 14 of the land groove 46, is denoted as Wsgu, and the groove bottom width, which is the distance between the groove walls at the groove bottom 50, is denoted as Wsgl, the land groove 46 satisfies the relationship of Wsgu < Wsgl. When chamfering is provided at the radially outer end of the groove wall 48 in the tire diameter direction, the groove width Wsgu is the distance between the intersection points of the extension line of the surface of the groove wall 48 and the extension line of the tread surface 14. When the space between the groove wall 48 and the groove bottom 50 is rounded, the groove bottom width Wsgl is the shortest distance between the intersection points of the extension line of the surface of the groove wall 48 and the extension line of the surface of the groove bottom 50, that is, the distance in the direction perpendicular to the extending direction of the land groove 46.

[0026] In plan view, the distances between the groove walls of the plurality of land grooves 46 shown in FIG. 1 are the same in the extending direction of the land grooves 46. Here, "the same" includes the case where the difference from the average value of the groove widths at three points with different positions in the extending direction of the land groove 46 is within ±10%.

[0027] As shown in FIG. 3, it is preferable that the groove depth of the land groove 46 gradually increases from the indentation side toward the kick-out side. That is, when the groove depth of the land groove 46 at the connection portion with the widthwise groove 16 on the indentation side is denoted as Dsgf, and the groove depth of the land groove 46 at the connection portion with the widthwise groove 16 on the kick-out side is denoted as Dsgr, it is preferable that the land groove 46 satisfies the relationship of Dsgf < Dsgr.

[0028] The tire 10 shown in FIG. 1 has, as the connection portion 22, a first connection portion 22L provided on the shoulder land portion 20 on one side (the left side in FIG. 1) in the tire width direction, and a second connection portion 22R provided on the shoulder land portion 20 arranged on the other side (the right side in FIG. 1) in the tire width direction.

[0029] The first connection portion 22L will be described with reference to FIG. 4. The first connection portion 22L provided on the first left shoulder land portion partitioned by the first left width groove 24 and the second left width groove 26 will be described. The first connection portion 22L has four land grooves 46 and is X-shaped in plan view. The first connection portion 22L has an intersection portion 54A, an indentation side connection portion 56, and a kick-out side connection portion 58.

[0030] The intersection 54A is formed by four narrow grooves 46 intersecting each other. The intersection 54A is located between the first left-width groove 24 on the stepping side and the second left-width groove 26 on the kicking side, which demarcate the shoulder land portion 20. The stepping-side connection 56 connects the intersection 54A and the first left-width groove 24. The kicking-side connection 58 connects the intersection 54A and the second left-width groove 26.

[0031] The kick-off side connection portion 58 has two narrow grooves 46 that are inclined in opposite directions relative to the tire circumferential direction, centered on the intersection portion 54A. That is, in a plan view, the kick-off side connection portion 58 is V-shaped, extending from the intersection portion 54A toward the second left width groove 26. The kick-off side connection portion 58 has a foot-in side edge 58F and a kick-off side edge 58R on both sides in the tire width direction relative to the intersection portion 54A.

[0032] In the kicking-side connection portion 58, the foot-side edge 58F is formed between the foot-side groove wall 48 of the pair of groove walls 48 of the V-shaped narrow grooves 46 and the tread surface 14. The angle α between the groove wall 48 of the foot-side edge 58F and the tread surface 14 (hereinafter referred to as the "edge angle") is less than 90 degrees because the groove wall 48 is inclined in the direction in which the distance between the groove walls widens toward the inside in the radial direction of the tire.

[0033] Each of the stepping-side edges 58F is connected to the widthwise groove 16 on the kicking-out side, inclined toward the intersection 54A on the stepping-side side, and connected to the stepping-side connection 56. The distance between the pair of stepping-side edges 58F gradually decreases from the kicking-out side to the stepping-out side, and is shortest at the intersection 54A. The distance between the pair of stepping-side edges 58F at the intersection 54A is the same as the distance between the groove walls of the narrow groove 46. The angle θsgx between the two narrow grooves at the kicking-side connection 58 of the first connection 22L is preferably 30 degrees or more and 90 degrees or less. The angle θsgx is the angle between the pair of stepping-side edges 58F.

[0034] In the push-off side connection portion 58, the push-off side edge 58R is formed between the push-off side groove wall 48 of the pair of groove walls 48 of the V-shaped narrow grooves 46 and the tread surface 14. The edge angle of the push-off side edge 58R is less than 90 degrees. The push-off side edge 58R and the widthwise groove 16 on the push-off side demarcate an inverted triangular block 60R in plan view, with its apex on the push-off side.

[0035] The foot-operated side connection portion 56 of the first connection portion 22L has two narrow grooves 46 that are inclined in opposite directions with respect to the tire circumferential direction, centered on the intersection portion 54A. That is, in a plan view, the foot-operated side connection portion 56 of the first connection portion 22L is in an inverted V shape that extends from the intersection portion 54A toward the first left width groove 24. The foot-operated side connection portion 56 has a foot-operated side edge 56F and a kick-off side edge 56R on both sides in the tire width direction relative to the intersection portion 54A.

[0036] At the foot-side connection portion 56, the foot-side edge 56F is formed between the foot-side groove wall 48 of the pair of groove walls 48 of the narrow grooves 46 arranged in an inverted V shape and the tread surface 14. The edge angle of the foot-side edge 56F is less than 90 degrees. The pair of foot-side edges 56F intersect at the intersection portion 54A, inclined toward each other on the foot-side, and connect to the widthwise groove 16 on the foot-side. The foot-side edge 56F and the first left width groove 24 demarcate a triangular block 60F in plan view, with its apex on the push-off side.

[0037] In the foot-side connection section 56, the kick-off side edge 56R is formed between the kick-off groove wall 48 of the pair of groove walls 48 of the inverted V-shaped narrow grooves 46 and the tread surface 14. The edge angle of the kick-off side edge 56R is less than 90 degrees. The pair of kick-off side edges 56R are inclined away from each other from the intersection 54A toward the kick-off side and are connected to the widthwise groove 16 on the foot-side.

[0038] The second connecting section 22R will be described with reference to Figure 5. Note that components similar to those of the first connecting section 22L shown in Figure 4 are denoted by the same reference numerals and their descriptions are omitted. The second connecting section 22R, located on the second right shoulder land area 44, which is partitioned by the second right width groove 32 and the third right width groove 34, will be described. The second connecting section 22R is Y-shaped in plan view. The second connecting section 22R has an intersection 54B, a stepping-side connecting section 62, and a kicking-out side connecting section 58B.

[0039] The intersection 54B is formed by three narrow grooves intersecting each other. The intersection 54B is located between the second right-width groove 32 on the foot-stepping side and the third right-width groove 34 on the kick-off side. The foot-stepping side connection 62 connects the intersection 54B and the second right-width groove 32. The kick-off side connection 58B connects the intersection 54B and the third right-width groove 34.

[0040] The kick-out side connection portion 58B has two narrow grooves 46 that are inclined in opposite directions relative to the tire circumferential direction, centered on the intersection portion 54B. That is, in a plan view, the kick-out side connection portion 58B is V-shaped, extending from the intersection portion 54B toward the third right-width groove 34. The kick-out side connection portion 58B has a foot-in side edge 58F and a kick-out side edge 58R on both sides of the intersection portion 54B in the tire width direction. The distance between the pair of foot-in side edges 58F gradually decreases from the kick-out side to the foot-in side, and is shortest at the intersection portion 54B. The distance between the pair of foot-in side edges 58F at the intersection portion 54B is the same as the distance between the groove walls of the narrow grooves 46.

[0041] The angle θsgy between the two narrow grooves in the kick-out side connection portion 58B of the second connection portion 22R is preferably 60 degrees or more and 90 degrees or less. The angle θsgy is the angle between the pair of foot-in side edges 58F. The foot-in side connection portion 62 of the second connection portion 22R has one narrow groove 46 extending in the circumferential direction of the tire. That is, in a plan view, the foot-in side connection portion 62 of the second connection portion 22R is I-shaped, extending from the intersection portion 54B toward the widthwise groove 16 on the foot-in side. The foot-in side connection portion 62 extends in a direction along the circumferential direction of the tire.

[0042] Hereafter, when the first connection part 22L and the second connection part 22R are not distinguished, they will simply be referred to as the connection part. The intersection 54 is preferably located approximately in the center of the shoulder land portion 20 in the tire width direction, where the connecting portion 22 is provided. That is, if Xc is the distance in the tire width direction between the tire contact end E and the intersection 54, and Pa is the distance in the tire width direction between the tire contact end E and the tire width direction edge of the shoulder land portion 20, then it is preferable that the distance Xc and the distance Pa satisfy the following relationship (1).

[0043] Pa × 0.4 ≤ Xc ≤ Pa × 0.6 ···(1)

[0044] Distance Xc is the distance in the tire width direction between the intersection point P of the centerlines of the groove widths of each narrow groove 46 intersecting at the intersection 54 and the tire contact edge E. Distance Pa is the distance between the innermost edge 20E in the tire width direction of the shoulder land portion 20 where the connecting portion 22 is provided and the tire contact edge E.

[0045] The intersection 54 is preferably located approximately in the center of the tire circumferential direction of the shoulder land portion 20 where the connecting portion 22 is provided. In other words, it is preferable that the intersection P of the intersection 54 is located at the center between two points where a line passing through the intersection and perpendicular to the extending direction of the widthwise groove 16 on the kicking side or the widthwise groove 16 on the stepping side intersects with the kicking side end and the stepping side end of the shoulder land portion 20.

[0046] If Wg is the groove width of the widthwise groove 16 that demarcates the footing side of the shoulder land portion 20 where the connecting portion 22 is provided, it is preferable that the groove width Wsgu of the narrow groove 46 and the groove bottom width Wsgl satisfy the relationship shown in equation (2) below.

[0047] Wg × 0.4 ≤ Wsgu <Wsgl≦Wg×0.8···(2)

[0048] The groove width Wg is the groove width of the widthwise groove 16 at the point where a straight line L, which passes through the intersection point P of the centerlines of the groove widths of each narrow groove 46 intersecting at the intersection 54 and intersects the widthwise groove 16 perpendicular to the extension direction of the widthwise groove 16 on the stepping side, intersects the widthwise groove 16.

[0049] If Dg is the groove depth of the widthwise groove 16 that demarcates the stepping side of the shoulder land portion 20 where the connecting portion 22 is provided, it is preferable that the groove depth Dsgf of the narrow groove 46 at the connection portion with the widthwise groove 16 on the stepping side and the groove depth Dsgr of the narrow groove 46 at the connection portion with the widthwise groove 16 on the kicking side satisfy the relationship given by the following formula (3).

[0050] Dg × 0.6 ≤ Dsgf <Dsgr≦Dg×1.0···(3)

[0051] The groove depth Dg is defined as the groove depth of the widthwise groove 16 at the point where a straight line L, which passes through the intersection point P of the centerlines of the groove widths of each narrow groove 46 intersecting at the intersection 54 and intersects the widthwise groove 16 perpendicular to the extension direction of the widthwise groove 16 on the stepping side, intersects the widthwise groove 16.

[0052] By satisfying equation (3) above, as shown in Figure 3, the groove depth of the narrow groove 46 at the connection point with the widthwise groove 16(26) on the stepping side is shallower than the groove depth of the narrow groove 46 at the connection point with the widthwise groove 16(28) on the kicking side. That is, the narrow groove 46 has a raised bottom portion 64 at the stepping side end. By having the raised bottom portion 64 in the narrow groove 46, the shoulder base portion 20 can suppress the decrease in block rigidity on the stepping side of the shoulder base portion 20.

[0053] The tire 10 of this embodiment, as described above, is obtained through the usual manufacturing processes, namely the mixing process of tire materials, the processing process of tire materials, the molding process of the green tire, the vulcanization process, and the inspection process after vulcanization. When manufacturing the tire 10 of this embodiment, protrusions and recesses corresponding to a predetermined tread pattern are formed on the inner wall of the vulcanization mold, and vulcanization is performed using this mold.

[0054] (Mechanism of Action and Effects) Water is discharged from the inside in the tire width direction to the outside in the tire width direction through inclined grooves 36 provided on the tread surface 14. The water discharged through the inclined grooves 36 is then discharged towards the push-off side in the tire circumferential direction through circumferential grooves 18, and further discharged outward in the tire width direction through widthwise grooves 16.

[0055] The widthwise grooves 16 are connected to connecting parts 22 provided on the adjacent shoulder land area 20 in the circumferential direction of the tire. A portion of the water flowing through the widthwise grooves 16 flows through the connecting parts 22 and along the shoulder land area 20 from the foot-in side to the foot-out side in the circumferential direction of the tire. Therefore, the tire 10 discharges water from the inside in the tire width direction to the outside in the tire width direction, and also discharges water from the foot-in side to the foot-out side in the circumferential direction of the tire, resulting in superior wet performance.

[0056] The connecting portion 22 has a kick-out side connecting portion 58 between the intersection portion 54 and the kick-out side widthwise groove 16. The kick-out side connecting portion 58 has two narrow grooves 46 that are inclined in opposite directions relative to the tire circumferential direction with respect to the intersection portion 54, and traction performance is obtained when the grooves tilt toward the foot-pressing side during braking. Furthermore, since the edge angle of the foot-pressing side edge 58F in the kick-out side connecting portion 58 is less than 90 degrees, the edge effect that grips the road surface more reliably is increased. Therefore, the tire 10 can exhibit better snow performance when braking.

[0057] Furthermore, the distance between the pair of foot-facing edges 56F and 58F gradually decreases from the kicking side to the foot-facing side, and is shortest at the intersections 54 and 54B. Therefore, snow accumulates at the intersections 54 and 54B during braking, and by compacting this snow, superior snow performance can be achieved.

[0058] By satisfying the relationship Wsgu < Wsgl between the groove width Wsgu at the groove opening 52 on the tread surface 14 of the fine groove 46 and the groove bottom width Wsgl at the groove bottom 50, it is possible to achieve both wet performance and snow performance. That is, by widening the groove bottom width Wsgl, a large opening area can be obtained, and by narrowing the groove width Wsgu, a decrease in block rigidity can be suppressed.

[0059] Since the groove depth of the fine groove 46 gradually increases from the indentation side toward the kicking-out side, it is difficult to resist the water flowing in the fine groove 46. Therefore, the tire 10 can smoothly discharge water through the fine groove 46, and thus higher wet performance can be obtained.

[0060] By satisfying the relationship of the following formula (1) between the distance Xc in the tire width direction between the tire ground end E and the intersection 54 and the distance Pa in the tire width direction between the tire ground end E of the shoulder land portion 20 and the tire width direction edge of the shoulder land portion 20, the deviation of the block rigidity in the shoulder land portion 20 can be suppressed.

[0061] Pa × 0.4 ≤ Xc ≤ Pa × 0.6 ··· (1)

[0062] Therefore, the tire 10 can suppress the collapse of the fine groove 46 constituting the connecting portion 22 during braking and driving, and suppress the deterioration of snow performance and wet performance.

[0063] In a plan view, for the X-shaped first connecting portion 22L, the angle θsgx formed between the two fine grooves 46 in the kicking-out side connecting portion 58 is 30 degrees or more and 90 degrees or less. By the angle θsgx being 3 degrees or more, the indentation side edge 58F is more surely formed on the shoulder land portion 20. By the angle θsgx being 90 degrees or less, a decrease in the land area of the shoulder land portion 20 can be suppressed. Thereby, the first connecting portion 22L combines the kicking-out side connecting portion 58 and the indentation side connecting portion 56 to more surely exhibit an edge effect during braking. Therefore, the tire 10 can more surely obtain excellent snow performance and wet performance.

[0064] In a plan view, the Y-shaped second connecting portion 22R has an included angle θsgy between two fine grooves 46 in the kicking-out side connecting portion 58B of 60 degrees or more and 90 degrees or less. When the included angle θsgy is 60 degrees or more, a sufficient edge effect can be exhibited during braking in the second connecting portion 22R where the stepping-in side connecting portion 62 is I-shaped. When the included angle θsgy is 90 degrees or less, a decrease in the land area of the shoulder land portion 20 can be suppressed. Therefore, the tire 10 can more surely obtain excellent snow performance and wet performance.

[0065] By satisfying the relationship of the following formula (2) for the groove width Wg, the groove width Wsgu, and the groove bottom width Wsgl of the width direction groove 16 that partitions the stepping-in side of the shoulder land portion 20 where the connecting portion 22 is provided, more excellent snow performance and wet performance can be obtained.

[0066] Wg × 0.4 ≤ Wsgu < Wsgl ≤ Wg × 0.8 ··· (2)

[0067] That is, when the groove width Wsgu and the groove bottom width Wsgl are Wg × 0.4 or more, the water flowing through the width direction groove 16 on the stepping-in side more smoothly passes through the connecting portion 22 and is discharged to the kicking-out side. When the groove width Wsgu and the groove bottom width Wsgl are Wg × 0.8 or less, the block area in the shoulder land portion 20 can be maintained at a predetermined value or more.

[0068] By satisfying the relationship Dsgf < Dsgr for the groove depth Dg of the width direction groove 16 that partitions the stepping-in side of the shoulder land portion 20 where the connecting portion 22 is provided and the groove depth Dsgf of the fine groove 46 at the connecting portion with the width direction groove 16 on the stepping-in side, the water flowing through the width direction groove 16 on the stepping-in side more smoothly passes through the connecting portion 22 and is discharged to the kicking-out side. ​​​​​ Dg × 0.6 ≤ Dsgf <Dsgr≦Dg×1.0···(3)

[0071] In other words, when the groove depths Dsgf and Dsgr are Dg × 0.6 or greater, water flowing through the widthwise grooves 16 on the footing side passes more smoothly through the connection section 22 and is discharged to the kicking side. When the groove depths Dsgf and Dsgr are Dg × 1.0 or less, the block rigidity of the shoulder landing section 20 can be maintained above a predetermined level.

[0072] The narrow grooves 46 of the kick-out side connection portion 58, which are inclined in opposite directions relative to the tire's circumferential direction, tilt toward the kick-out side during driving, thereby providing traction. Since the angle of the kick-out side edge 58R is less than 90 degrees, the edge effect that grips the road surface more reliably is increased. Therefore, the tire 10 can exhibit excellent snow performance even when driving.

[0073] (modified version) The present invention is not limited to the embodiments described above and can be modified as appropriate within the scope of the spirit of the invention.

[0074] For example, the tire has been described as having a first X-shaped connecting portion and a second Y-shaped connecting portion in a plan view, but the present invention is not limited to this. That is, the tire only needs to have at least one of the first connecting portion and the second connecting portion as a connecting portion.

[0075] In the case of the tire shown in Figure 1, the present invention has been described as having a first connection on one side in the tire width direction and a second connection on the other side in the tire width direction, but the present invention is not limited to this. The tire may have a second connection on one side in the tire width direction and a first connection on the other side in the tire width direction, or the first and second connection parts may be arranged alternately in the tire circumferential direction.

[0076] In the above-described implementation configuration, the groove depth of the narrow groove gradually increases from the foot-stepping side to the kick-off side; however, the present invention is not limited to this. The groove depth of the narrow groove may be the same from the foot-stepping side to the kick-off side.

[0077] In the above embodiment, the groove width in a plan view of the narrow groove was described as being the same, but the present invention is not limited to this, and the groove width may increase gradually or in stages from the stepping side to the kicking side.

[0078] In the above embodiment, the connection portion was described as having an X-shaped first connection portion and a Y-shaped second connection portion in a plan view. However, the present invention is not limited to this, and may also be in an inverted Y shape. An inverted Y-shaped connection portion can achieve the same effects as in the above embodiment by having an intersecting portion. [Examples]

[0079] This document describes the results of manufacturing a tire corresponding to the invention defined in the claims of this application and evaluating its performance on snow and wet surfaces.

[0080] (sample) Examples 1 to 46 and a comparative example tire were manufactured with a tire size of 245 / 45R19 102V (as defined by JATMA), and having the shape shown in Figure 1 when mounted on a rim. The detailed conditions of these tires are shown in Tables 1 and 2 below. The examples are tires having the intersection described in the above examples. Specifically, Examples 1 to 23 are tires with an X-shaped connection in plan view, formed by four narrow grooves as shown in Figure 4. Examples 24 to 46 are tires with a Y-shaped connection in plan view, formed by three narrow grooves as shown in Figure 5. In contrast, Reference Example 1 is the same as Example 1 except that it does not have a connection. Reference Example 2 is the same as Example 1 except that it does not intersect but has two narrow grooves connecting the widthwise groove on the footing side and the widthwise groove on the kicking side.

[0081] In Tables 1 and 2, the "Connection" column indicates the presence or absence of a connection, and the "Intersection" column indicates the presence or absence of an intersection. Furthermore, "Xc / Pa", "θsgx", "θsgy", "Wsgu / Wg", "Wsgl / Wg", "Dsgf / Dg", and "Dsgr / Dg" are defined according to the above descriptions.

[0082] The tires manufactured in this manner, according to Examples 1 to 46 and Reference Examples 1 and 2, were mounted on rims with a rim size of 19 x 8.0J at an air pressure (F / R) of 230 kPa / 230 kPa. Each test tire was then mounted on a front-wheel-drive test vehicle (2000cc engine displacement), and its performance was evaluated according to the following procedure.

[0083] (Snow performance) The test vehicle was driven on a compacted snow surface, and the braking distance was measured when braking was applied at an initial speed of 40 km / h. The results obtained were recorded in the "Snow Braking Performance" column of Tables 1 and 2 as an index, with the value of Reference Example 1 set to 100. A larger index indicates a shorter braking distance and superior braking performance.

[0084] (Wet performance) The test vehicle was driven on a wet road surface with a water depth of 2 mm, and the braking distance from an initial speed of 100 km / h to a complete stop was measured. Based on these measurement results, an index was set to set the value in Reference Example 1 to 100, and this index is listed in the "Wet Performance" column of Tables 1 and 2. A larger index indicates a shorter braking distance and superior performance.

[0085] [Table 1]

[0086] [Table 2]

[0087] Examples 1-46 were found to have superior snow and wet performance compared to Reference Example 1 due to the presence of an intersecting section. Reference Example 2, having a connecting section, had superior wet performance compared to Reference Example 1, which did not have a connecting section, but its snow performance was inferior to Examples 1 and 24 because it did not have an intersecting section. [Explanation of Symbols]

[0088] 10 tires 12 Tread section 14 Tread surface 16 Width groove 18 Circumferential groove 20 Shoulder Track and Field Club 20E Innermost edge 22 Connection part 22L 1st connection part 22R Second connection section 24. First left wide groove 26. Second left wide groove 28 Third left wide ditch 30 1st right width groove 32 2nd right width groove 34 3rd right width groove 36 Slant groove 38. 1st Left Shoulder Track and Field Club 40 2nd left shoulder track and field 42. 1st Right Shoulder Track and Field Club 44. 2nd Right Shoulder Track and Field Club 46 Narrow groove 48 Ditch wall 50 groove bottom 52 Groove opening 54, 54B intersection 56. Foot-operated connection part (first connection part) 56F Stepping edge 56R kicking edge 58. Kicking-side connection part (first connection part) 58B Kicking-out side connection part (second connection part) 58F Stepping edge 58R kicking edge 60F, 60R Block 62 Step-on connection part (second connection part) 64 Raised base E Ground end P intersection (intersection) CP Tire Equatorial Plane EL ground terminal wire

Claims

1. A tire having a tread portion with a tread surface, and having a specified direction of rotation, In the tread portion, Multiple widthwise grooves extending in the direction along the tire width and connecting to the tire contact edge, provided at intervals in the circumferential direction of the tire, Multiple circumferential grooves extending in a direction along the circumferential direction of the tire and connecting to each other in the width direction grooves, Multiple shoulder land portions are provided outside the tire width direction from the multiple circumferential grooves, and are partitioned by the multiple widthwise grooves and the multiple circumferential grooves. The system includes a connecting portion formed in at least a portion of the aforementioned multiple shoulder land portions, which connects the widthwise groove on the stepping side and the widthwise groove on the kicking side that demarcate the shoulder land portion, The connecting portion is formed of a plurality of narrow grooves having a groove width that gradually increases from the tread surface toward the groove bottom, and includes an intersection where the plurality of narrow grooves intersect, a foot-side connecting portion that connects the intersection with the widthwise groove on the foot-stepping side, and a kick-off side connecting portion that connects the intersection with the widthwise groove on the kick-off side. The kick-off side connection portion has two narrow grooves that are inclined in opposite directions relative to the tire circumferential direction, with respect to the intersection portion as the center.

2. The tire according to claim 1, wherein the groove depth of the plurality of fine grooves gradually increases from the stepping side to the kicking side.

3. The tire according to claim 1, wherein the distance Xc in the tire width direction between the tire contact end and the intersection and the distance Pa in the tire width direction between the tire contact end of the shoulder land portion and the tire width direction edge of the shoulder land portion satisfy the following equation (1). Pa × 0.4 ≤ Xc ≤ Pa × 0.6 ... (1)

4. The tire according to claim 1, wherein the angle between the two narrow grooves in the kick-out side connection portion is 60 degrees or more and 90 degrees or less.

5. The aforementioned foot-operated connecting portion has two narrow grooves that are inclined in opposite directions with respect to the tire circumferential direction, with respect to the intersection as the center. The tire according to claim 1, wherein the angle between the two narrow grooves in the kick-out side connection portion is 30 degrees or more and 90 degrees or less.

6. The tire according to claim 1, wherein the groove width Wsgu on the tread surface of the plurality of narrow grooves, the groove bottom width Wsgl at the bottom of the grooves, and the groove width Wg of the widthwise grooves that define the footing side of the shoulder land portion satisfy the relationship of the following formula (2). Wg × 0.4 ≤ Wsgu < Wsgl ≤ Wg × 0.8 ... (2)

7. The tire according to claim 1, wherein the groove depth Dsgf on the stepping side of the plurality of narrow grooves, the groove depth Dsgr on the kicking side, and the groove depth Dg of the widthwise groove that demarcates the stepping side of the shoulder land portion satisfy the relationship of formula (3) below. Dg × 0.6 ≤ Dsgf < Dsgr ≤ Dg × 1.0 ... (3)

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