pneumatic tires

Abstract

To provide a pneumatic tire having excellent drainage performance and traction performance.SOLUTION: A pneumatic tire includes: a circumferential groove 10 extending in a zigzag shape by alternately arranging first groove parts 14 and second groove parts 15; and a first land part 40 and a second land part 41 disposed on one side and the other side of a tire axial direction WD of the circumferential groove 10. A first lateral groove 20 disposed in the first land part 40 has a first opening 16 opened in the first groove part 14. One groove wall 22a of the first lateral groove 20 is connected to a second groove wall 15a at the first land part side partitioning the first land part 40 in the second groove part 15, and extends along the second groove wall 15a at the land part side. A second lateral groove 30 disposed in the second land part 41 has a second opening 17 opened in the first groove part 14 and longer in a tire circumferential direction CD than the first opening 16. One groove wall 30a of the second lateral groove 30 is connected to a second groove wall 15b at the second land part side partitioning the second land part 41 in the second groove part 15, and the second opening 17 is disposed on an extension line of the second groove wall 15a at the first land part side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a pneumatic tire. [Background technology]

[0002] Conventionally, pneumatic tires have been known that have main grooves that extend in a zigzag pattern in the tire circumferential direction. Such pneumatic tires have excellent traction due to the zigzag main grooves, but their drainage performance is prone to decline.

[0003] Therefore, a pneumatic tire is known in which lateral grooves are provided in land portions separated by zigzag main grooves, as in Patent Document 1. In such a pneumatic tire, water can pass through the lateral grooves, thereby improving drainage performance, but further improvement in drainage performance is desired. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2010-105446 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pneumatic tire with good drainage and traction. [Means for solving the problem]

[0006] The pneumatic tire of this embodiment includes a circumferential groove extending in the tire circumferential direction, a first land portion provided on one side of the circumferential groove in the tire axial direction, and a second land portion provided on the other side of the circumferential groove in the tire axial direction. and arranged axially outward of the first land portion.a plurality of first lateral grooves provided in the first land portion at intervals in the tire circumferential direction, and a plurality of second lateral grooves provided in the second land portion at intervals in the tire circumferential direction, wherein the circumferential grooves extend in a zigzag pattern by alternately arranging first groove portions inclined with respect to the tire circumferential direction and second groove portions shorter than the first groove portions and inclined in the opposite direction to the first groove portions with respect to the tire circumferential direction, and the first lateral grooves are formed by alternately arranging first groove portions inclined with respect to the tire circumferential direction and second groove portions shorter than the first groove portions and inclined in the opposite direction to the first groove portions, and one groove wall of the first lateral groove is connected to a first land portion-side second groove wall that defines the first land portion in the second groove portion and extends along the first land portion-side second groove wall, the second lateral groove has a second opening that opens into the first groove portion and is longer in the tire circumferential direction than the first opening, one groove wall of the second lateral groove is connected to a second land portion-side second groove wall that defines the second land portion in the second groove portion, and the second opening is provided on an extension of the first land portion-side second groove wall, an angle of the second land portion-side second groove wall with respect to the tire circumferential direction is larger than an angle of the first land portion-side second groove wall with respect to the tire circumferential direction, The first transverse groove is provided with a bottom-raised portion formed by raising the groove bottom to reduce the groove depth, and the bottom-raised portion Groove A pneumatic tire with grooves that gradually become deeper toward the center. [Effects of the Invention]

[0007] The pneumatic tire described above has good drainage and traction, particularly due to the above-described structures of the first lateral groove and the second lateral groove. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a pneumatic tire according to an embodiment of the present invention; [Figure 2] A development diagram showing the tread pattern of the pneumatic tire of Figure 1. [Figure 3] Enlarged view of the main part of the tread pattern in Figure 2 [Figure 4] Cross section of line IV-IV in Figure 2 DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will be described below with reference to the drawings. Unless otherwise specified, the shapes and dimensions in this specification are those of a tire mounted on a standard rim and inflated to standard internal pressure under normal load. A standard rim is a "standard rim" in the JATMA standard, a "design rim" in the TRA standard, or a "measuring rim" in the ETRTO standard. Standard internal pressure is the "maximum air pressure" in the JATMA standard, the "maximum value" listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, or the "inflation pressure" in the ETRTO standard.

[0010] As shown in FIG. 1, a pneumatic tire 1 has bead portions 2 on both axial sides of the tire. Each bead portion 2 is composed of a bead core 2a made of a circularly wound steel wire and a rubber bead filler 2b provided radially outside the bead core 2a. A carcass ply 5 is stretched across the bead portions 2 on both axial sides of the tire. The carcass ply 5 is a sheet-like member made of a large number of ply cords arranged in a direction perpendicular to the tire circumferential direction and covered with rubber. The carcass ply 5 forms the framework of the pneumatic tire 1 between the bead portions 2 on both axial sides of the tire, and is folded back around the bead portions 2 from the axially inner side to the axially outer side to encase the bead portions 2. A sheet-like inner liner 6 made of rubber with low air permeability is attached to the inside of the carcass ply 5.

[0011] One or more belts 7 are provided on the radially outer side of the carcass ply 5. The belt 7 is a member made of a large number of steel cords covered with rubber. A tread 3 having a contact surface with the road surface (hereinafter referred to as the "contact surface") is provided on the radially outer side of the belt 7. Sidewall rubber 4 is provided on both sides of the carcass ply 5 in the axial direction of the tire. In addition to these components, components such as an underbelt pad and a chafer are provided as required for the function of the pneumatic tire 1.

[0012] Figure 2 is a partial development view of a tread 3 of a tire according to one embodiment. In the figure, the symbol CL indicates the tire equatorial plane, which corresponds to the tire axial center. The symbol WD indicates the tire axial direction (also referred to as the tire width direction), with the inner side in the tire axial direction WD referring to the direction approaching the tire equatorial plane CL and the outer side in the tire axial direction WD referring to the direction away from the tire equatorial plane CL. The symbol CD indicates the tire circumferential direction, which is a circumferential direction centered on the tire rotational axis. Also, in Figure 1, the symbol RD indicates the tire radial direction (a direction perpendicular to the tire rotational axis), with the inner side in the tire radial direction RD referring to the direction approaching the tire rotational axis and the outer side in the tire radial direction RD referring to the direction away from the tire rotational axis.

[0013] The tire of this embodiment is a tire that has a designated front and back when mounted on a vehicle, that is, a designated side that is mounted on the outside and a designated side that is mounted on the inside when mounted on a vehicle. Therefore, a marking for designating the mounting orientation on a vehicle is provided on, for example, the sidewall of the tire. In Figures 1 and 2, the tire is mounted on a vehicle so that one side in the tire axial direction WD indicated by the symbol OUT faces outward (outside of the vehicle) when mounted on the vehicle, and the other side in the tire axial direction WD indicated by the symbol IN faces inward (inside of the vehicle) when mounted on the vehicle.

[0014] A plurality of main grooves 10, 11, 12, and 13 extending in the tire circumferential direction CD are provided at intervals in the tire axial direction WD on the surface of the tread 3. The main grooves 10, 11, 12, and 13 are generally circumferential grooves that are continuous in the tire circumferential direction CD and have a groove width (opening width) of 5 mm or more.

[0015] In this example, four main grooves 10, 11, 12, and 13 are provided on the surface of the tread 3, namely, a first center main groove 10 located on the vehicle inner side of the tire equatorial plane CL, a second center main groove 11 located on the vehicle outer side of the tire equatorial plane CL, a first shoulder main groove 12 located between the first center main groove 10 and the ground contact edge E1 on one side of the tire axial direction WD (inner side of the vehicle), and a second shoulder main groove 13 located between the second center main groove 11 and the ground contact edge E2 on the other side of the tire axial direction WD (outer side of the vehicle).

[0016] The first center main groove 10 is composed of a first groove portion 14 that extends linearly and inclined toward one side of the tire axial direction WD relative to the tire circumferential direction, and a second groove portion 15 that is shorter than the first groove portion 14 and extends linearly and inclined toward the opposite direction (the other side of the tire axial direction WD) relative to the tire circumferential direction CD. The first groove portions 14 and the second groove portions 15 are arranged alternately, thereby forming a zigzag shape for the first center main groove 10.

[0017] The first groove portion 14 has a center land portion-side first groove wall 14a that defines the center land portion 40 and a mediate land portion-side first groove wall 14b that defines the first mediate land portion 41, which are provided parallel to each other.

[0018] In the second groove portion 15, a center land portion-side second groove wall 15a that defines the center land portion 40 and a mediate land portion-side second groove wall 15b that defines the first mediate land portion 41 form different angles with respect to the tire circumferential direction CD. In this example, the angle θ1 of the center land portion-side second groove wall 15a with respect to the tire circumferential direction CD is larger than the angle θ2 of the mediate land portion-side second groove wall 15b with respect to the tire circumferential direction CD (see FIG. 3).

[0019] The second center main groove 11, the first shoulder main groove 12, and the second shoulder main groove 13 are all straight grooves extending parallel to the tire circumferential direction CD.

[0020] The tread 3 has a plurality of land portions defined by the main grooves 10, 11, 12, and 13. Specifically, a center land portion 40 is defined on the tire equatorial plane CL between the first center main groove 10 and the second center main groove 11. On one axially WD side of the center land portion 40, a first intermediate land portion 41 is defined between the first center main groove 10 and the first shoulder main groove 12, and a first shoulder land portion 43 is defined between the first shoulder main groove 12 and the ground contact edge E1 on one axially WD side of the tire. On the other axially WD side of the center land portion 40, a second intermediate land portion 42 is defined between the second center main groove 11 and the second shoulder main groove 13, and a second shoulder land portion 44 is defined between the second shoulder main groove 13 and the ground contact edge E2 on the other axially WD side of the tire.

[0021] The second intermediate land portion 42 is formed as a continuous rib in the tire circumferential direction CD, and the other land portions, i.e., the center land portion 40, the first intermediate land portion 41, the first shoulder land portion 43 and the second shoulder land portion 44, are separated by lateral grooves extending in the tire axial direction WD and form rows of multiple blocks aligned in the tire circumferential direction CD.

[0022] This example is characterized by a tread pattern of a center land portion 40 and a first intermediate land portion 41 defined by a zigzag first center main groove 10. The configurations of the center land portion 40 and the first intermediate land portion 41 will be described in detail below.

[0023] The center land portion 40 has a plurality of first lateral grooves 20 arranged at intervals in the tire circumferential direction CD, crossing the center land portion 40. The center land portion 40 has a block row in which a plurality of blocks (center blocks) defined by the plurality of first lateral grooves 20 and the two center main grooves 10, 11 are arranged in the tire circumferential direction CD.

[0024] As shown enlarged in FIG. 3, the first transverse groove 20 has a bent shape with a bent portion 21, and in this example, is formed in a V-shaped bent shape in a plan view.

[0025] The first lateral groove 20 is composed of a first lateral groove portion 22 extending from a bend 21 to communicate with the first center main groove 10, and an other lateral groove portion 23 extending from the bend 21 to communicate with the second center main groove 11. The bend 21 is located closer to the first center main groove 10 than the tire equatorial plane CL and forms an acute angle.

[0026] On the other hand, the lateral groove portion 22 is formed so that the first opening 16 opens into the first groove portion 14 of the first center main groove 10 and extends along the second groove portion 15 so as to include the connecting position between the first groove portion 14 and the second groove portion 15 in the first center main groove 10.

[0027] Specifically, one groove wall 22a of the one lateral groove portion 22 is connected to the center land portion-side second groove wall 15a that defines the center land portion 40 in the second groove portion 15 of the first center main groove 10, and is provided along the center land portion-side second groove wall 15a.

[0028] The other groove wall 22b of one lateral groove portion 22 is connected to a center land portion-side first groove wall 14a that defines the center land portion 40 in the first groove portion 14.

[0029] In this example, the other groove wall 22b is gradually closer to the one groove wall 22a toward the bend 21, so that the groove width of the one lateral groove portion 22 gradually narrows from the first opening 16 toward the bend 21. However, the other groove wall 22b may be parallel to the one groove wall 22a, so that the one lateral groove portion 22 has a constant groove width. Also, the acute angle formed between the one lateral groove portion 22 and the first center main groove 10 may have a rounded tip.

[0030] In this specification, the phrase "one groove wall 22a of one lateral groove portion 22 is arranged along the center land portion side second groove wall 15a" refers not only to the case where one groove wall 22a is on the same plane as the center land portion side second groove wall 15a (i.e., parallel to the center land portion side second groove wall 15a), but also to the case where the angle θ3 between the one groove wall 22a and the center land portion side second groove wall 15a is 150 degrees or more and 210 degrees or less.

[0031] The angle θ4 of one groove wall 22a with respect to the tire circumferential direction CD is preferably smaller than the angle θ1 of the center land portion-side second groove wall 15a with respect to the tire circumferential direction CD. Furthermore, the angle θ3 between one groove wall 22a and the center land portion-side second groove wall 15a is preferably 150 degrees or greater and 180 degrees or less. The angle θ4 of one groove wall 22a with respect to the tire circumferential direction CD is preferably 10 degrees or greater and 80 degrees or less, and the angle θ1 of the center land portion-side second groove wall 15a with respect to the tire circumferential direction CD is preferably 10 degrees or greater and 80 degrees or less.

[0032] The second lateral groove portion 23 is a lateral groove portion that extends in a straight line from the bend portion 21 toward the second center main groove 11 and is connected to the second center main groove 11. The second lateral groove portion 23 is a lateral groove portion that extends in a direction that intersects the extending direction of the first lateral groove portion 22 and extends from the bend portion 21 to the same side as the first lateral groove portion 22 in the tire circumferential direction CD.

[0033] As shown in Figure 4, the first lateral groove 20 has a raised bottom portion 25, which is a shallow groove formed by raising the groove bottom. The raised bottom portion 25 is highest at the bend portion 21 side of the other lateral groove portion 23, and is formed in an inclined shape so that the groove depth gradually increases from there toward the first center main groove 10 and the second center main groove 11. The raised bottom portion 25 is formed across the entire groove width of the first lateral groove 20, connecting the front and rear blocks.

[0034] Furthermore, the central land portion 40 is provided with a plurality of sipes 27 extending in a direction parallel to the other lateral groove portion 23 at intervals in the tire circumferential direction CD. The sipes 27 are narrow grooves whose open ends toward the ground contact patch are closed under load. The sipes 27 are provided so as to cross the central land portion 40 in locations where no first lateral grooves 20 exist, and are also provided on extensions of the other lateral groove portion 23.

[0035] In the first intermediate land portion 41, a plurality of second lateral grooves 30 and a plurality of third lateral grooves 31 extending in the tire axial direction WD are alternately provided in the tire circumferential direction CD.

[0036] The plurality of third lateral grooves 31 extend from the first shoulder main groove 12 in the tire axial direction WD and terminate within the first intermediate land portion 41. The plurality of second lateral grooves 30 are provided between adjacent third lateral grooves 31 in the tire circumferential direction CD, connecting the first center main groove 10 and the first shoulder main groove 12 and crossing the first intermediate land portion 41. The first intermediate land portion 41 forms a block row in the tire circumferential direction CD, with the blocks (mediate blocks) defined by the plurality of second lateral grooves 30, the first center main groove 10, and the first shoulder main groove 12 being arranged in the tire circumferential direction CD.

[0037] The second lateral groove 30 has a second opening 17 that opens into the first groove portion 14 of the first center main groove 10 so as to include the connecting position between the first groove portion 14 and the second groove portion 15 in the first center main groove 10. The second opening 17 of the second lateral groove 30 is longer in the tire circumferential direction CD than the first opening 16 of the one lateral groove portion 22, and the second lateral groove 30 is provided along the second groove portion 15.

[0038] Specifically, one groove wall 30a of the second lateral groove 30 is connected to the mediate land portion-side second groove wall 15b that defines the first mediate land portion 41 in the second groove portion 15 of the first center main groove 10, and is provided along the mediate land portion-side second groove wall 15b.

[0039] The other groove wall 30b of the second lateral groove 30 is a mediate land portion-side first groove wall 14b that defines the first mediate land portion 41 in the first groove portion 14, and is connected to the mediate land portion-side second groove wall 15b at a position farther from the mediate land portion-side second groove wall 15b than an extension line L of the center land portion-side second groove wall 15a in plan view as shown in Figures 2 and 3.

[0040] As a result, a second opening 17 having a larger opening width along the tire circumferential direction CD than the first opening 16 of one lateral groove portion 22 is provided on the extension line L of the center land portion-side second groove wall 15a.

[0041] In this example, the tip of the acute corner 26 formed by the second lateral groove 30 and the first center main groove 10 may be rounded.

[0042] As shown in Figure 3, when the tip of a corner 24 formed by one groove wall 22a of one lateral groove portion 22 and the center land portion-side first groove wall 14a, or a corner 26 formed by the other groove wall 30b of the second lateral groove 30 and the center land portion-side first groove wall 14a is rounded, the distance in the tire circumferential direction CD from the intersection points P, Q of the extension lines of each groove wall to the center land portion-side second groove wall 15a or the mediate land portion-side second groove wall 15b is defined as the opening width of the first opening 16 and the second opening 17 in the tire circumferential direction CD.

[0043] As shown in Figure 4, the second lateral grooves 30 have raised groove bottoms 33 at their ends on the first center main groove 10 side, which are shallower grooves formed by raising the groove bottoms. The raised bottoms 33 are formed across the entire groove width of the second lateral grooves 30, connecting the front and rear blocks.

[0044] Furthermore, the first intermediate land portion 41 is provided with a plurality of sipes 34 extending in a direction parallel to the second lateral grooves 30 and the third lateral grooves 31. The sipes 34 are narrow grooves whose open ends toward the ground contact surface are closed under load. The sipes 34 are provided at intervals in the tire circumferential direction CD between the second lateral grooves 30 and the third lateral grooves 31.

[0045] In the pneumatic tire 1 of this embodiment, the first center main groove 10 has a zigzag shape, and therefore has excellent traction in the front-rear direction.

[0046] Furthermore, one groove wall 22a of the one-side lateral groove portion 22 is connected to the center land portion-side second groove wall 15a and extends along the center land portion-side second groove wall 15a, and the second opening 17 of the second lateral groove 30 is provided on the extension of the center land portion-side second groove wall 15a. Therefore, when driving on a wet road surface, water in the one-side lateral groove portion 22 is smoothly drained into the first center main groove 10 and is also easily drained from the second opening 17 through the second lateral groove 30 to the first shoulder main groove 12, improving drainage.

[0047] In addition, in this embodiment, the angle θ1 of the center land portion side second groove wall 15a relative to the tire circumferential direction CD and the angle θ2 of the intermediate land portion side second groove wall 15b relative to the tire circumferential direction CD are different angles, resulting in excellent traction.

[0048] In particular, when the angle θ1 of the center land portion side second groove wall 15a relative to the tire circumferential direction CD is larger than the angle θ2 of the intermediate land portion side second groove wall 15b relative to the tire circumferential direction CD, water in the one lateral groove portion 22 is more easily guided to the second lateral groove 30 by the center land portion side second groove wall 15a when driving on a wet road surface, thereby improving drainage.

[0049] The above-described embodiments are presented as examples and are not intended to limit the scope of the invention. This novel embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention.

[0050] For example, in the above embodiment, the first center main groove 10 is provided in a zigzag circumferential groove, and a one-sided lateral groove portion 22 is provided in the center land portion 40 as a first lateral groove, and the second lateral groove 30 is provided in the first intermediate land portion 41. However, any main groove such as the second center main groove 11 or shoulder main grooves 12, 13 may be provided in a zigzag circumferential groove, and lateral grooves similar to the one-sided lateral groove portion 22 and the second lateral groove 30 may be provided in each land portion on one side and the other side of the zigzag circumferential groove in the axial direction of the tire. [Explanation of symbols]

[0051] 1...pneumatic tire, 2...bead portion, 3...tread, 4...sidewall, 10...first center main groove, 11...second center main groove, 12...first shoulder main groove, 13...first shoulder main groove, 14...first groove portion, 14a...first groove wall on center land portion side, 14b...second groove wall on mediate land portion side, 15...second groove portion, 15a...second groove wall on center land portion side, 15b...mediate Second groove wall on the toe land portion side, 16...first opening, 17...second opening, 20...first lateral groove, 21...bend portion, 22...one side lateral groove portion, 23...other side lateral groove portion, 24...corner portion, 25...raised bottom portion, 26...corner portion, 30...second lateral groove, 31...third lateral groove, 40...center land portion, 41...first intermediate land portion, 42...second intermediate land portion, 43...first shoulder land portion, 44...second shoulder land portion

Claims

1. a circumferential groove extending in the tire circumferential direction; a first land portion provided on one side of the circumferential groove in the tire axial direction; a second land portion provided on the other side of the circumferential groove in the tire axial direction and disposed axially outward of the first land portion; a plurality of first lateral grooves provided in the first land portion at intervals in the tire circumferential direction; a plurality of second lateral grooves provided in the second land portion at intervals in the tire circumferential direction; In a pneumatic tire comprising: The circumferential groove extends in a zigzag pattern by alternately arranging first groove portions inclined with respect to the tire circumferential direction and second groove portions that are shorter than the first groove portions and inclined in the opposite direction to the first groove portions with respect to the tire circumferential direction, the first transverse groove has a first opening that opens into the first groove portion, one groove wall of the first transverse groove is connected to a first land portion-side second groove wall that defines the first land portion in the second groove portion and extends along the first land portion-side second groove wall, the second lateral groove has a second opening that opens into the first groove portion and is longer in the tire circumferential direction than the first opening, one groove wall of the second transverse groove is connected to a second land portion-side second groove wall that defines the second land portion in the second groove portion, the second opening is provided on an extension of the first land portion-side second groove wall, an angle of the second land portion-side second groove wall with respect to the tire circumferential direction is larger than an angle of the first land portion-side second groove wall with respect to the tire circumferential direction, The first lateral groove is provided with a bottom-raised portion formed by raising the groove bottom to reduce the groove depth, and the bottom-raised portion is inclined so that the groove depth gradually increases toward the first groove portion.

2. The pneumatic tire according to claim 1 , wherein the angle of the first land portion-side second groove wall with respect to the tire circumferential direction is 10 degrees or more.

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