JP7187939B2 - pneumatic tire - Google Patents

Description

The present invention relates to pneumatic tires.

Conventionally, the heavy duty pneumatic tire disclosed in, for example, Patent Literature 1 aims to improve both braking performance on ice and anti-skid performance on ice and snow while securing traction performance on snow. This heavy-duty pneumatic tire has a plurality of circumferential grooves continuous in a zigzag shape in the tire circumferential direction in the tread contact portion, and blocks are arranged adjacent to the circumferential grooves and spaced apart in the tire circumferential direction. A block pattern tire having a row of blocks, wherein each block of the row of blocks is provided with one or two sipes.

Conventionally, for example, a heavy-duty tire for icy and snowy roads described in Patent Document 2 achieves both improved turning performance on icy and snowy roads and improved straight running stability and steering stability when traveling on dry roads. It is intended to This heavy load tire for snow and ice roads has at least two main grooves extending in the circumferential direction on the tread, and has a pattern divided into a large number of blocks by the main grooves and sub-grooves intersecting the main grooves, Each block is provided with a sipe.

Conventionally, for example, the pneumatic tire described in Patent Literature 3 is aimed at preventing cracks from occurring in the bottom of the groove, producing low noise, and preventing uneven wear. This pneumatic tire has a tread portion provided with a plurality of circumferential grooves extending along the tire circumferential direction, the tread portion being divided into a plurality of land portions by the circumferential grooves, and A stepped land portion as a partial wear sacrificial portion is provided at the groove bottom portion separated from both groove walls.

Further, conventionally, for example, a heavy-duty tire described in Patent Document 4 aims to improve stone trapping performance while suppressing cracks at the bottom of grooves and deterioration of wettability. This heavy-duty tire has, in the tread portion, a plurality of circumferential grooves extending along the tire circumferential direction, and lateral grooves dividing the space between the circumferential grooves into a large number of blocks, and the circumferential grooves are zigzag-shaped. None.

Conventionally, for example, the pneumatic tire described in Patent Document 5 aims at improving noise performance without sacrificing snow performance. This pneumatic tire has a zigzag center circumferential main groove with a pitch length of Pc, a zigzag shoulder circumferential main groove with a pitch length of Ps, a center inclined lateral groove inclined at an angle θc, and an angle θs and shoulder inclined lateral grooves inclined at , where Ps>Pc and θs<θc.

JP-A-3-136911 JP-A-6-278413 JP 2008-174198 A JP 2011-230643 A JP 2016-113066 A

By the way, tires mounted on drive shafts of heavy-duty vehicles such as dump trucks are mainly required to have off-road traction performance. Therefore, both are required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic tire that achieves both off-road traction performance and quietness performance.

In order to solve the above-described problems and achieve the object, a pneumatic tire according to one aspect of the present invention is provided on a tread surface of a tread portion continuously in a zigzag shape along the tire circumferential direction. A pair of shoulder main grooves defining a shoulder land portion on the outside and a center land portion on the inside in the tire width direction, and a zigzag shape along the tire circumferential direction between the pair of shoulder main grooves on the tread surface. at least one center main groove extending continuously from the center main groove and dividing the center land portion into a plurality of blocks in the tire width direction; and a plurality of center sub-grooves provided by dividing the center land portion into a plurality of blocks in the tire circumferential direction, the center sub-grooves covering the entire center land portion. It has a see-through structure that penetrates and penetrates in a straight line.

Moreover, in the pneumatic tire according to one aspect of the present invention, it is preferable that the extension angle of the center sub-groove with respect to the tire circumferential direction of the see-through structure is in the range of 40° or more and 60° or less.

Further, in the pneumatic tire according to one aspect of the present invention, the contact width TW of the tread portion and the tire width direction dimension AW of the see-through structure formed by the center sub-groove satisfy 0.6≦AW/TW≦0.9. It is preferable to satisfy the relationship.

Further, in the pneumatic tire according to one aspect of the present invention, the tire width direction dimension CW of the center land portion and the tire width direction dimension AW of the see-through structure formed by the center sub-groove are 1.2≦AW/CW≦1. .6 is preferred.

Further, in the pneumatic tire according to an aspect of the present invention, it is preferable that the zigzag pitch length λce of the center main groove and the zigzag pitch length λsh of the shoulder main grooves satisfy the relationship λce<λsh.

Further, in the pneumatic tire according to one aspect of the present invention, the zigzag pitch length λce of the center main groove and the zigzag pitch length λsh of the shoulder main groove may satisfy the relationship of 2≦λsh/λce. preferable.

Further, in the pneumatic tire according to an aspect of the present invention, it is preferable that the zigzag amplitude Ace of the center main groove and the zigzag amplitude Ash of the shoulder main groove satisfy the relation Ace<Ash.

Further, in the pneumatic tire according to one aspect of the present invention, the contact width TW of the tread portion and the zigzag amplitude Ash of the shoulder main groove satisfy the relationship of 0.05≦Ash/TW≦0.25. is preferred.

Further, in the pneumatic tire according to one aspect of the present invention, the contact width TW of the tread portion and the zigzag amplitude Ace of the center main groove satisfy a relationship of 0.01≦Ace/TW≦0.10. is preferred.

Further, in the pneumatic tire according to one aspect of the present invention, both groove walls of the shoulder main groove overlap in the tire width direction when viewed from the tire circumferential direction, and the groove width A of the shoulder main groove and the width A of the shoulder main groove It is preferable that the dimension B in the tire width direction of the overlapping shoulder main grooves satisfies the relationship of 0.1≦B/A≦0.4.

Further, in the pneumatic tire according to one aspect of the present invention, the center main groove, the center sub-groove, the shoulder main groove, and the shoulder sub-groove communicate from the center main groove outward in the tire width direction. It is preferable that the groove width is gradually increased from the center main groove toward the outside in the tire width direction.

Further, in the pneumatic tire according to one aspect of the present invention, the groove width LL of the shoulder sub-groove and the pitch length PL of the shoulder sub-groove have a relationship of 0.2≦LL/PL≦0.5 at the contact edge. is preferably satisfied.

Further, in the pneumatic tire according to one aspect of the present invention, the shoulder land portion and the center land portion are provided on the tread surface with a groove width narrower and a groove depth shallower than the main grooves and the sub grooves. It is preferable that a thin shallow groove is formed through each block.

Further, in the pneumatic tire according to one aspect of the present invention, it is preferable that the narrow shallow groove has bent portions in at least two locations.

According to the present invention, since the center sub-groove has a see-through structure, an edge component penetrating the center land portion in a substantially straight line is ensured, and the edge effect can be sufficiently exhibited. As a result, off-road traction performance can be improved. Moreover, since the shoulder main groove 15A and the center main groove 15B are formed in a zigzag shape along the tire circumferential direction, it is possible to suppress passage of sound in the tire circumferential direction. As a result, quiet performance can be improved.

FIG. 1 is a meridional cross-sectional view of a pneumatic tire according to an embodiment of the invention. FIG. 2 is a plan view of the pneumatic tire according to the embodiment of the invention. FIG. 3 is a chart showing results of performance tests of pneumatic tires according to examples of the present invention. FIG. 4 is a chart showing results of performance tests of pneumatic tires according to examples of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. Also, the constituent elements described in the following embodiments can be combined, and some constituent elements can be omitted.

FIG. 1 is a meridional cross-sectional view of a pneumatic tire according to this embodiment. FIG. 2 is a plan view of the pneumatic tire according to this embodiment.

In the following description, the tire width direction refers to the direction parallel to the tire rotation axis of the pneumatic tire 1, and the tire width direction inner side refers to the direction toward the tire equatorial plane CL in the tire width direction. The outer side refers to a direction away from the tire equatorial plane CL in the tire width direction. In addition, the tire radial direction refers to a direction orthogonal to the tire rotation axis, the tire radial direction inner side refers to the direction toward the tire rotation axis in the tire radial direction, and the tire radial direction outer side refers to the tire in the tire radial direction. Refers to the direction away from the axis of rotation. Moreover, the tire circumferential direction refers to the direction in which the tire rotates around the tire rotation axis.

The tire equatorial plane CL is a plane orthogonal to the tire rotation axis and passing through the center of the tire width direction. refers to the center line where the In the present embodiment, the tire equatorial plane CL and the tire equator line are given the same reference numeral "CL".

The pneumatic tire 1 in this embodiment is a tubeless tire. Further, the pneumatic tire 1 in this embodiment is a heavy-duty pneumatic tire to be mounted on trucks and buses. Truck and bus tires (heavy duty pneumatic tires) are defined in Chapter C of the Japan Automobile Tire Manufacturers Association (JATMA) published by the Japan Automobile Tire Manufacturers Association (JATMA YEAR BOOK). It means a tire that can be Note that the pneumatic tire 1 may be mounted on a passenger car or may be mounted on a small truck.

A pneumatic tire 1 of the present embodiment has a tread portion 2 made of a rubber material at the outermost portion in the tire radial direction when viewed in a meridional cross section as shown in FIG. The surface of the tread portion 2 , that is, the portion that contacts the road surface when the vehicle on which the pneumatic tire 1 is mounted is formed as a tread surface 3 .

Both ends of the tread portion 2 in the tire width direction are formed as shoulder portions 4, and sidewall portions 5 are arranged from the shoulder portions 4 to a predetermined position on the inner side in the tire radial direction. That is, the sidewall portions 5 are arranged at two locations on both sides of the pneumatic tire 1 in the tire width direction.

Further, a bead portion 10 is positioned inside each sidewall portion 5 in the tire radial direction. The bead portions 10 are arranged at two locations on both sides of the tire equatorial plane CL, similarly to the sidewall portions 5 . That is, the pair of bead portions 10 are arranged on both sides in the tire width direction of the tire equatorial plane CL. A bead core 11 and a bead filler 12 are provided on each of the pair of bead portions 10 . The bead core 11 is formed by winding a bead wire, which is a steel wire, into a ring shape. The bead filler 12 is arranged outside the bead core 11 in the tire radial direction.

The bead portion 10 is configured so that it can be mounted on a regular rim with a 15° taper. The term "specified rim" as used herein refers to the "applicable rim" specified by JATMA, the "design rim" specified by TRA, or the "measuring rim" specified by ETRTO. That is, the pneumatic tire 1 according to the present embodiment can be mounted on a regular rim in which the portion to be fitted with the bead portion 10 is inclined at an inclination angle of 15° with respect to the rotation axis.

A belt layer 7 is provided inside the tread portion 2 in the tire radial direction. The belt layer 7 has, for example, a multilayer structure in which four layers of belts 71, 72, 73, and 74 are laminated. The belts 71, 72, 73, 74 are constructed by coating a plurality of belt cords made of steel with coat rubber and rolling them. Further, the inclination angles of the belts 71, 72, 73, 74 with respect to the tire circumferential direction are set within a range of, for example, 15° or more and 70° or less. Some of the four layers of belts 71, 72, 73 and 74 are arranged so that the belt cords intersect between the layers. The belt cords intersect each other between the belts 72 and 73 of the second and third layers from the inner circumference of the tire that function as strength layers, and between the belts 71 and 72 of the first and second layers from the inner circumference of the tire, The belt cords are inclined in the same direction, and the belt cords are also inclined in the same direction between the third and fourth belts 73 and 74 from the inner peripheral side of the tire.

A carcass layer 6 containing radial ply cords is continuously provided inside the belt layer 7 in the tire radial direction and inside the sidewall portion 5 . This carcass layer 6 is supported by a pair of bead cores 11 . The carcass layer 6 has a single-layer structure consisting of one carcass ply, and is toroidally spanned in the tire circumferential direction between the bead cores 11 arranged on both sides in the tire width direction. configure. Specifically, the carcass layer 6 is disposed from one bead portion 10 to the other bead portion 10 of the pair of bead portions 10 located on both sides in the tire width direction, and wraps the bead core 11 and the bead filler 12. As shown, the bead portion 10 is wound outward along the bead core 11 and the bead filler 12 in the tire width direction. That is, the carcass layer 6 passes from the inner side of the bead core 11 in the tire width direction to the inner side of the bead core 11 in the tire radial direction, and extends to the outer side of the bead core 11 and the bead filler 12 in the tire width direction. and bead filler 12. The carcass plies of the carcass layer 6 arranged in this manner are formed by coating a carcass cord made of steel with a coating rubber and rolling the coated rubber.

An inner liner 8 is formed along the carcass layer 6 inside the carcass layer 6 or on the inner side of the carcass layer 6 in the pneumatic tire 1 . The inner liner 8 is the inner surface of the tire, that is, the inner peripheral surface of the carcass layer 6, and both end portions in the tire width direction reach the lower portions of the bead cores 11 and the bead toes of the pair of bead portions 10, and are formed in a toroidal shape in the tire circumferential direction. It is hung around and attached. The inner liner 8 is for suppressing permeation of air molecules and has no cord.

The tread pattern will be described below. As shown in FIGS. 1 and 2, the tread surface 3 of the tread portion 2 is formed with a plurality of main grooves 15 extending continuously in the tire width direction along the tire circumferential direction. At least three main grooves 15 need only be provided on the tread surface 3 . The main groove 15 is continuously provided in a zigzag shape along the tire circumferential direction. The main grooves 15 include a pair of shoulder main grooves 15A provided on both outermost sides in the tire width direction, and at least one (one in this embodiment) center groove provided between each shoulder main groove 15A. and a main groove 15B.

Each shoulder main groove 15A defines a shoulder land portion 16 on the outside in the tire width direction. Further, each shoulder main groove 15A defines a center land portion 17 on the inner side in the tire width direction between them.

The center main groove 15B divides the center land portion 17 into a plurality (two in this embodiment) in the tire width direction between the shoulder main grooves 15A. In this embodiment, one center main groove 15B is provided and arranged on the tire equatorial plane CL. Although not shown in the drawing, the center main groove 15B may be plural and may not be arranged on the tire equatorial plane CL.

As shown in FIG. 2 , shoulder sub-grooves 18 are provided in the tread surface 3 of the shoulder land portion 16 . A plurality of shoulder sub-grooves 18 are arranged side by side in the tire circumferential direction, one end of which is open to communicate with the shoulder main groove 15A, and the other end of which is open to the ground contact edge T, thereby forming a plurality of shoulder land portions 16 in the tire circumferential direction. shoulder block 16A. One end of the shoulder sub-groove 18 is open to communicate with a bent portion on the outside in the tire width direction of the shoulder main groove 15A having a zigzag shape.

Here, the ground contact edge T is the tire width of the area where the tread surface 3 contacts a flat surface when 100% of the specified load is applied with the pneumatic tire 1 mounted on the specified rim and filled with the specified internal pressure. are the two outermost ends of the direction. Further, the tire width direction dimension of the area where the tread surface 3 at this time contacts the flat surface and the tire width direction dimension between the both ground contact edges T is referred to as a ground contact width TW. The specified internal pressure is the maximum air pressure specified by JATMA, the maximum value specified by TRA "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", or the "INFLATION PRESSURES" specified by ETRTO. The specified load is the "maximum load capacity" defined by JATMA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" defined by TRA, or the "LOAD CAPACITY" defined by ETRTO.

As shown in FIG. 2 , a center sub-groove 19 is provided on the tread surface 3 of each center land portion 17 . A plurality of center minor grooves 19 are arranged in parallel in the tire circumferential direction, one end of which opens to communicate with the shoulder main groove 15A, and the other end of which opens to the center main groove 15B adjacent to the shoulder main groove 15A in the tire width direction. Thus, each center land portion 17 is divided into a plurality of center blocks 17A in the tire circumferential direction. One end of the center sub-groove 19 is open to communicate with a bent portion on the inner side in the tire width direction of the zigzag-shaped shoulder main groove 15A, and the other end is opened on the bent portion on the outer side in the tire width direction of the zigzag-shaped center main groove 15B. and communicate with each other.

Although not shown in the figure, when a plurality of center main grooves 15B are provided, the center minor groove 19 has one end between the center main grooves 15B adjacent to each other in the tire width direction. , and the other end opens and communicates with the other center main groove 15B, so that the center land portion 17 partitioned between the center main grooves 15B adjacent to each other in the tire width direction is opened in the tire circumferential direction. is divided into a plurality of center blocks 17A. In this case, one end and the other end of the center sub-groove 19 are open and communicate with the bent portions facing each other in the zigzag-shaped center main grooves 15B adjacent to each other in the tire width direction.

As shown in FIG. 2, the tread surface 3 of each block 16A, 17A is provided with thin shallow grooves 20. As shown in FIG. One end of the shallow groove 20 opens to communicate with the shoulder main groove 15A in the shoulder block 16A, and the other end opens to the ground contact edge T, thereby dividing the shoulder block 16A in the tire circumferential direction. One end of the narrow shallow groove 20 is open and communicates with one of the main grooves 15 adjacent in the tire width direction in the center block 17A, and the other end is open and communicates with the other main groove 15, so that the center Block 17A is divided in the tire circumferential direction. Although one shallow groove 20 is provided in one block 16A, 17A in this embodiment, a plurality of shallow grooves 20 may be provided. Further, the thin shallow groove 20 has a bent portion 20A bent in the middle. At least two bent portions 20A are provided.

The narrow shallow groove 20 is formed to have a narrow groove width and a shallow groove depth with respect to the main groove 15 and the sub grooves 18 and 19. Specifically, the groove width is 2 mm or less and the groove depth is 2 mm. is formed below. The groove depth of the center main groove 15B changes through the stepped portion 31 . The center main groove 15B has a groove depth of 6 mm or more and 12 mm or less (9 mm in this embodiment) and a groove width of 7 mm or more and 13 mm or less (10 mm in this embodiment) at the portion defined by the stepped portion 31 . The center main groove 15B has the same portion as the center sub-groove 19 that is partitioned by the stepped portion 31 and connected to the center sub-groove 19. The groove depth is 13 mm or more and 19 mm or less (16 mm in this embodiment), and the groove width is It is 7 mm or more and 13 mm or less (10 mm in this embodiment). The shoulder main groove 15</b>A and the center sub-groove 19 have different groove depths via a stepped portion 32 . Further, the shoulder main groove 15</b>A has a partially changed groove depth via the stepped portion 33 and the stepped portion 34 . The shoulder minor groove 18 has the same groove depth as a part of the shoulder main groove 15A through the stepped portions 32, 33, and 34, and has a different groove depth than the center minor groove 19 and a part of the shoulder main groove 15A. is doing. A portion of the shoulder main groove 15A has a groove depth of 10 mm or more and 17 mm or less (13 mm in this embodiment) and a groove width of 15 mm or more and 19 mm or less (13 mm in this embodiment) at a portion defined by the stepped portions 33 and 34. 17 mm). A portion of the shoulder main groove 15A and the shoulder minor groove 18 have a groove depth of 18 mm or more and 24 mm or less (21 mm in the present embodiment) and a groove width of 21 mm at the portions defined by the stepped portions 32, 33, and 34. 27 mm or less (24 mm at the ground end T in this embodiment).

The pneumatic tire 1 of this embodiment has a see-through structure in which the center sub-groove 19 straightly penetrates and penetrates the entire center land portion 17 . That is, the center minor groove 19 penetrates the center land portion 17 partitioned between the pair of shoulder main grooves 15A to both shoulder main grooves 15A. In addition, it has a see-through structure so that one side of the shoulder main groove 15A side and the other side of the shoulder main groove 15A can be seen straight through without being obstructed by both groove walls of the center sub-groove 19.例文帳に追加In addition, the see-through structure of the center sub-groove 19 penetrates both the ground contact ends T together with the shoulder sub-groove 18 penetrating the shoulder land portion 16, and when the shoulder sub-groove 18 and the center sub-groove 19 are viewed in the extending direction, , the groove walls of the shoulder sub-groove 18 and the center sub-groove 19 may be configured so that the groove walls of the one grounding end T side and the other grounding end T side can be seen straight through.

According to this pneumatic tire 1, since the center sub-groove 19 has a see-through structure, an edge component penetrating the center land portion 17 in a substantially straight line is ensured, and the edge effect can be sufficiently exhibited. As a result, off-road traction performance can be improved. In addition, according to the pneumatic tire 1, the shoulder main groove 15A and the center main groove 15B are formed in a zigzag shape along the tire circumferential direction, thereby suppressing passage of sound in the tire circumferential direction. As a result, quietness performance (external noise resistance performance) can be improved.

Further, in the pneumatic tire 1 of the present embodiment, the extension angle θ of the see-through structure of the center sub-groove 19 with respect to the tire circumferential direction is in the range of 40° or more and 60° or less. In the see-through structure, when the center sub-groove 19 is viewed in the extending direction, one side of the shoulder main groove 15A can be seen through the other shoulder main groove 15A without being obstructed by both groove walls of the center sub-groove 19. It is composed of two parallel lines extending from one shoulder main groove 15A side to the other shoulder main groove 15A side in plan view. In FIG. 2, the see-through structure is indicated by a single line due to its minute width. The extension angle θ of the see-through structure is the angle of a line extending from one shoulder main groove 15A side to the other shoulder main groove 15A side in plan view with respect to the tire circumferential direction. This extension angle θ includes the case where the see-through structure penetrates from one grounding end T side to the other grounding end T side.

According to this pneumatic tire 1, by setting the extension angle θ of the see-through structure in the center sub-groove 19 with respect to the tire circumferential direction to be 40° or more, the hammering sound when the center block 17A touches the road surface can be reduced in the tire circumferential direction. can be shifted. As a result, quiet performance can be improved. Further, by setting the extension angle θ of the see-through structure in the center sub-groove 19 to 60° or less with respect to the tire circumferential direction, an edge component in the tire circumferential direction is ensured, and the edge effect can be sufficiently exhibited. As a result, off-road traction performance can be improved. In order to obtain the above effects, it is preferable to set the extension angle θ of the see-through structure in the center sub-groove 19 with respect to the tire circumferential direction to a range of 45° or more and 55° or less.

Further, in the pneumatic tire 1 of the present embodiment, the contact width TW of the tread portion 2 and the tire width direction dimension AW of the see-through structure formed by the center sub-groove 19 satisfy the relationship of 0.6≦AW/TW≦0.9. Fulfill.

The relationship 0.6≦AW/TW≦0.9 indicates that the tire width direction dimension AW of the see-through structure is smaller than the contact width TW of the tread portion 2, and the see-through structure extends from one contact end T side to the other contact end T side. It does not include the case where it penetrates to the side of the grounding end T, and it means that it terminates inside the grounding width TW. That is, the tire width direction dimension AW of the see-through structure is the maximum dimension of the see-through structure reaching both shoulder land portions 16 . According to the pneumatic tire 1, the see-through structure terminates inside the ground contact width TW, thereby suppressing passage of sound outward in the tire width direction. As a result, quiet performance can be improved. By setting AW/TW to be 0.6 or more, it is possible to secure the tire width direction dimension AW of the see-through structure and secure off-road traction performance. On the other hand, according to this pneumatic tire 1, by setting AW/TW to 0.9 or less, it is possible to secure the effect of suppressing passage of sound to the outside in the tire width direction, and improve quiet performance. In order to obtain the above effect, it is preferable that the contact width TW and the tire width direction dimension AW of the see-through structure satisfy the relationship of 0.7≦AW/TW≦0.8.

Further, in the pneumatic tire 1 of the present embodiment, the tire width direction dimension CW of the center land portion 17 and the tire width direction dimension AW of the see-through structure formed by the center sub-groove 19 are 1.2≤AW/CW≤1.6. satisfy the relationship Here, the tire width direction dimension CW of the center land portion 17 is the maximum dimension in the tire width direction.

According to this pneumatic tire 1, by setting AW/CW to be 1.2 or more, the tire width direction dimension AW of the see-through structure is secured with respect to the tire width direction dimension CW of the center land portion 17, and the tire can be used off-road. of traction performance can be ensured. On the other hand, according to this pneumatic tire 1, by setting AW/CW to 1.6 or less, it is possible to ensure the effect of suppressing passage of sound to the outer side in the tire width direction, and improve quietness performance. Note that the tire width direction dimension CW of the center land portion 17 and the tire width direction dimension AW of the see-through structure preferably satisfy the relationship of 1.3≦AW/CW≦1.5 in order to obtain the above effect.

In addition, in the pneumatic tire 1 of the present embodiment, the zigzag pitch length λce of the center main groove 15B and the zigzag pitch length λsh of the shoulder main groove 15A satisfy the relationship λce<λsh. Here, the zigzag pitch length λce of the center main groove 15B and the zigzag pitch length λsh of the shoulder main groove 15A indicate the maximum amplitude.

According to this pneumatic tire 1, the zigzag pitch length λsh of the shoulder main groove 15A is made larger than the zigzag pitch length λce of the center main groove 15B, so that the edge effect of the shoulder main groove 15A is sufficiently exhibited. can. As a result, off-road traction performance can be improved. In addition, according to the pneumatic tire 1, by making the zigzag pitch length λsh of the shoulder main groove 15A and the zigzag pitch length λce of the center main groove 15B different, the hitting sound when contacting the road surface is reduced. , the resonance is suppressed, and the hammering sound of the center main groove 15B having a small pitch length λce is in a high frequency band, so that the noise outside the vehicle can be reduced. As a result, quiet performance can be improved.

Further, in the pneumatic tire 1 of the present embodiment, the zigzag pitch length λce of the center main groove 15B and the zigzag pitch length λsh of the shoulder main groove 15A satisfy the relationship of 2≦λsh/λce.

According to this pneumatic tire 1, λsh/λce is 2 or more, and the zigzag pitch length λsh of the shoulder main groove 15A is set longer than the zigzag pitch length λce of the center main groove 15B. The edge effect at 15A can be fully exhibited. As a result, off-road traction performance can be improved. Further, according to the pneumatic tire 1, λsh/λce is set to 2 or more, and the zigzag pitch length λsh of the shoulder main groove 15A and the zigzag pitch length λce of the center main groove 15B are different, Regarding the hammering sound when the tread surface 3 touches the road surface, the resonance is suppressed and the hammering sound of the center main groove 15B having a small pitch length λce is in a high frequency band, so that the noise outside the vehicle can be reduced. As a result, quiet performance can be improved. It is preferable that the pitch length λce and the pitch length λsh satisfy the relationship 2≦λsh/λce≦4. When λsh/λce exceeds 4, the shoulder main groove 15A becomes nearly linear and the zigzag shape of the center main groove 15B becomes finer, resulting in a tendency of lowering the traction performance.

Further, in the pneumatic tire 1 of the present embodiment, the zigzag amplitude Ace of the center main groove 15B and the zigzag amplitude Ash of the shoulder main groove 15A satisfy the relationship of Ace<Ash. Here, the zigzag amplitude Ace of the center main groove 15B and the zigzag amplitude Ash of the shoulder main groove 15A indicate maximum amplitudes.

According to this pneumatic tire 1, by increasing the amplitude Ash of the zigzag shape of the shoulder main groove 15A, the edge effect of the shoulder main groove 15A can be sufficiently exhibited, and the off-road traction performance can be improved. Further, according to the pneumatic tire 1, by reducing the amplitude Ace of the zigzag shape of the center main groove 15B, it is possible to reduce the hammering sound of the center main groove 15B when the tread surface 3 touches the road surface, resulting in quiet performance. can be improved. The amplitudes Ash and Ace preferably satisfy the relationship of 2≤Ash/Ace≤4 in order to obtain the above effect, and the above effect is achieved by satisfying the relationship of 2.5≤Ash/Ace≤3.5. It is more preferable to obtain

Further, in the pneumatic tire 1 of the present embodiment, the contact width TW of the tread portion 2 and the zigzag amplitude Ash of the shoulder main groove 15A satisfy the relationship of 0.05≦Ash/TW≦0.25.

According to this pneumatic tire 1, by setting Ash/TW to 0.05 or more, the edge effect in the shoulder main groove 15A can be exhibited, and the off-road traction performance can be improved. On the other hand, according to this pneumatic tire 1, by setting Ash/TW to 0.25 or less, it is possible to suppress hammering noise in the shoulder main groove 15A when the tread surface 3 touches the road surface, and to ensure quiet performance. Note that the ground width TW and the amplitude Ash preferably satisfy the relationship of 0.10≤Ash/TW≤0.20 in order to obtain the above effect.

Further, in the pneumatic tire 1 of the present embodiment, the contact width TW of the tread portion 2 and the zigzag amplitude Ace of the center main groove 15B satisfy the relationship of 0.01≦Ace/TW≦0.10.

According to this pneumatic tire 1, by setting Ace/TW to 0.01 or more, the edge effect in the center main groove 15B can be exhibited, and the off-road traction performance can be improved. On the other hand, according to this pneumatic tire 1, by setting Ace/TW to 0.10 or less, it is possible to suppress the hammering sound in the center main groove 15B when the tread surface 3 touches the road surface, and to ensure quiet performance. Note that the ground width TW and the amplitude Ace preferably satisfy the relationship 0.04≦Ace/TW≦0.06 in order to obtain the above effect.

Further, in the pneumatic tire 1 of the present embodiment, the groove width A of the shoulder main groove 15A and the tire width direction dimension B where both groove walls of the shoulder main groove 15A are overlapped satisfy 0.1≦B/A≦0.1. It satisfies the relationship of 4. Here, the groove width A of the shoulder main groove 15A is the maximum groove width, and the tire width direction dimension B is the maximum dimension.

According to this pneumatic tire 1, by setting B/A to 0.1 or more, while ensuring the contribution of the shoulder main grooves 15A to the traction performance, the shoulder main grooves 15A overlap in the tire circumferential direction. It is possible to secure the effect of suppressing the passage of the sound and improve the quietness performance. On the other hand, according to this pneumatic tire 1, by setting B/A to 0.4 or less, the overlap structure becomes excessive and the zigzag shape of the shoulder main groove 15A becomes large, so that the tread surface 3 does not touch the road surface. Quiet performance can be ensured by suppressing an increase in hammering sound when the ball hits the ground. Note that the groove width A of the shoulder main groove 15A and the overlapping dimension B of the shoulder main groove 15A in the tire width direction should satisfy the relationship 0.2≦B/A≦0.3 in order to obtain the above effect. preferable.

Further, in the pneumatic tire 1 of the present embodiment, the center main groove 15B, the center sub-groove 19, the shoulder main groove 15A, and the shoulder sub-groove 18 are provided so as to communicate from the center main groove 15B outward in the tire width direction. , the groove width gradually increases from the center main groove 15B toward the outside in the tire width direction.

According to this pneumatic tire 1, the center main groove 15B, the center sub-groove 19, the shoulder main groove 15A, and the shoulder sub-groove 18 are provided so as to communicate from the center main groove 15B outward in the tire width direction. By securing the edge component in the tire width direction and gradually increasing the groove width toward the outside in the tire width direction, it is possible to secure the edge effect on the shoulder side and improve off-road traction performance. can.

Further, in the pneumatic tire 1 of the present embodiment, at the ground contact edge T, the groove width LL of the shoulder sub-groove 18 and the pitch length PL of the shoulder sub-groove 18 satisfy the relationship of 0.2≦LL/PL≦0.5. Fulfill. Here, the groove width LL of the shoulder sub-groove 18 and the pitch length PL of the shoulder sub-groove 18 indicate the maximum dimension at the ground contact edge T.

According to this pneumatic tire 1, by setting LL/PL to 0.2 or more, the groove width LL is secured with respect to the pitch length PL of the shoulder sub-groove 18, thereby improving off-road traction performance. be able to. On the other hand, according to this pneumatic tire 1, by setting LL/PL to 0.5 or less, the groove width LL is prevented from becoming excessively large with respect to the pitch length PL of the shoulder sub-groove 18. It is possible to secure the effect of suppressing the passage of sound to the outside in the width direction, and improve the quietness performance. Note that the groove width LL of the shoulder sub-groove 18 and the pitch length PL of the shoulder sub-groove 18 preferably satisfy the relationship of 0.3≦LL/PL≦0.4 in order to obtain the above effect.

In the pneumatic tire 1 of the present embodiment, the shoulder land portion 16 and the center land portion 17 are provided on the tread surface 3 with a narrower groove width and a shallower groove depth than the main groove 15 and the sub grooves 18 and 19. A thin shallow groove 20 is formed through each of the blocks 16A and 17A.

According to the pneumatic tire 1, the edge effect is ensured on the tread surface 3 of each block 16A, 17A by the thin shallow grooves 20, and the off-road traction performance can be improved.

Further, in the pneumatic tire 1 of the present embodiment, the thin shallow groove 20 has at least two bent portions 20A.

According to this pneumatic tire 1, the extended length of the thin and shallow grooves 20 is extended by the bent portions 20A in at least two places, the edge effect is further ensured, and the off-road traction performance is improved. can.

In addition, in the pneumatic tire 1 of the present embodiment, the zigzag pitch number Psh of the shoulder main groove 15A and the zigzag pitch number Pce of the center main groove 15B satisfy the relationship of Psh<Pce. When there are a plurality of center main grooves 15B, at least one center main groove 15B should satisfy the above relationship, but it is preferable that all center main grooves 15B satisfy the above relationship. Further, in the pneumatic tire 1 of the present embodiment, both groove walls of the shoulder main groove 15A overlap in the tire width direction when viewed from the tire circumferential direction, and the shoulder main groove 15A penetrates linearly in its extending direction. Does not have a see-through structure.

According to the pneumatic tire 1, the zigzag pitch number Psh of the shoulder main groove 15A is set smaller than the zigzag pitch number Pce of the center main groove 15B. can be set large, and the edge effect in the shoulder main groove 15A can be sufficiently exhibited. As a result, off-road traction performance can be improved. Further, according to the pneumatic tire 1, the tread surface 3 is grounded on the road surface by making the zigzag pitch number Psh of the shoulder main groove 15A and the zigzag pitch number Pce of the center main groove 15B different. Regarding the striking sound at the time, resonance is suppressed, and the striking sound of the center main groove 15B having a large pitch number Pce is in a high frequency band, so that the noise outside the vehicle can be reduced. Furthermore, according to the pneumatic tire 1, the shoulder main groove 15A and the center main groove 15B are formed in a zigzag shape along the tire circumferential direction, and the shoulder main groove 15A does not have a see-through structure. , the transmission of sound in the tire circumferential direction can be suppressed. As a result, quiet performance can be improved.

In this example, performance tests were conducted on off-road traction performance and quietness performance on a plurality of types of pneumatic tires under different conditions (see FIGS. 3 and 4).

In this performance test, a pneumatic tire of tire size 11R22.5 (heavy duty pneumatic tire) was mounted on a specified rim, inflated to a specified air pressure, and mounted on the drive shaft of a test vehicle (2-DD truck).

The traction performance is evaluated by running the test vehicle on an off-road (gravel road) at a speed of 30 km/h and measuring the difference between the speed of the test vehicle and the rotation speed of the drive shaft of the test vehicle. Then, based on the measurement results, index evaluation is performed using the conventional measurement value (speed difference) as a reference value (100). This evaluation shows that the smaller the speed difference and the larger the value, the better the off-road traction performance.

Quietness performance is evaluated by measuring passing sound (external noise) when a test vehicle is driven on an ISO (International Organization for Standardization) test course at 70 km/h. Then, index evaluation is performed using the measured value (passing sound dB) of the conventional example as a reference value (100). This evaluation shows that the higher the numerical value, the smaller the passing noise and the better the quietness performance.

3 and 4, the conventional example and each example are based on the tread pattern shown in FIG. In the conventional example, the center sub-groove does not have a see-through structure. On the other hand, in each example, the center sub-groove has a see-through structure.

As shown in the test results of FIGS. 3 and 4, the pneumatic tire of each example has improved off-road traction performance and quietness.

1 pneumatic tire 2 tread portion 3 tread surface 15 main groove 15A shoulder main groove 15B center main groove 16 shoulder land portion 16A shoulder block 17 center land portion 17A center block 18 shoulder sub-groove 19 center sub-groove 20 narrow shallow groove 20A bending portion CL Tire equatorial plane Pce Pitch number of center main groove Psh Pitch number of shoulder main groove Ace Amplitude of center main groove Ash Amplitude of shoulder main groove λce Pitch length of center main groove λsh Pitch length of shoulder main groove T Contact edge TW Contact width AW Dimension of the see-through structure formed by the center sub-groove in the tire width direction θ Extension angle of the see-through structure formed by the center sub-groove CW Dimension of the center land portion in the tire width direction A Groove width of the shoulder main groove B Both groove walls of the shoulder main groove Overlapped tire width direction dimension LL Groove width of shoulder sub groove at ground contact edge PL Pitch length of shoulder sub groove at ground contact edge

Claims (13)

A pair of shoulder main grooves that are continuously provided in a zigzag pattern along the tire circumferential direction on the tread surface of the tread portion to define a shoulder land portion on the outside in the tire width direction and a center land portion on the inside in the tire width direction. When,
At least one center extending continuously in a zigzag shape along the tire circumferential direction between the pair of shoulder main grooves on the tread surface to divide the center land portion into a plurality of parts in the tire width direction. a main groove;
a plurality of shoulder sub-grooves provided by dividing the shoulder land portion into a plurality of blocks in the tire circumferential direction;
a plurality of center sub-grooves provided by dividing the center land portion into a plurality of blocks in the tire circumferential direction;
with
The center sub-groove has a see-through structure that penetrates and penetrates the entire center land portion in a straight line ,
A zigzag pitch length λce of the center main groove and a zigzag pitch length λsh of the shoulder main groove satisfy a relationship of λce<λsh,
pneumatic tires. A pair of shoulder main grooves that are continuously provided in a zigzag pattern along the tire circumferential direction on the tread surface of the tread portion to define a shoulder land portion on the outside in the tire width direction and a center land portion on the inside in the tire width direction. When,
At least one center extending continuously in a zigzag shape along the tire circumferential direction between the pair of shoulder main grooves on the tread surface to divide the center land portion into a plurality of parts in the tire width direction. a main groove;
a plurality of shoulder sub-grooves provided by dividing the shoulder land portion into a plurality of blocks in the tire circumferential direction;
a plurality of center sub-grooves provided by dividing the center land portion into a plurality of blocks in the tire circumferential direction;
with
The center sub-groove has a see-through structure that penetrates and penetrates the entire center land portion in a straight line ,
A zigzag pitch length λce of the center main groove and a zigzag pitch length λsh of the shoulder main groove satisfy a relationship of 2≦λsh/λce,
pneumatic tires. The pneumatic tire according to claim 1 or 2 , wherein the center sub-groove extends at an angle of 40° or more and 60° or less with respect to the tire circumferential direction of the see-through structure. The contact width TW of the tread portion and the tire width direction dimension AW of the see-through structure formed by the center sub - groove satisfy a relationship of 0.6≦AW/TW≦0.9. Pneumatic tires as described. 5. The tire width direction dimension CW of the center land portion and the tire width direction dimension AW of the see-through structure formed by the center sub - groove satisfy a relationship of 1.2≦AW/CW≦1.6. 1. A pneumatic tire according to 1. The pneumatic tire according to any one of claims 1 to 5 , wherein the zigzag amplitude Ace of the center main groove and the zigzag amplitude Ash of the shoulder main grooves satisfy the relation Ace<Ash. The pneumatic pneumatic tire according to any one of claims 1 to 6 , wherein the contact width TW of the tread portion and the zigzag amplitude Ash of the shoulder main groove satisfy a relationship of 0.05≤Ash/TW≤0.25. tire. The pneumatic tire according to any one of claims 1 to 7 , wherein the contact width TW of the tread portion and the zigzag amplitude Ace of the center main groove satisfy a relationship of 0.01≤Ace/TW≤0.10. tire. Both groove walls of the shoulder main groove overlap in the tire width direction when viewed from the tire circumferential direction, and the groove width A of the shoulder main groove and the overlapped tire width direction dimension B of the shoulder main groove are different. The pneumatic tire according to any one of claims 1 to 8 , which satisfies the relationship 0.1≤B/A≤0.4. The center main groove, the center sub-groove, the shoulder main groove, and the shoulder sub-groove are provided so as to communicate from the center main groove toward the outside in the tire width direction, and extend from the center main groove toward the outside in the tire width direction. The pneumatic tire according to any one of claims 1 to 9 , wherein the groove width is gradually increased. 11. The groove width LL of the shoulder sub-groove and the pitch length PL of the shoulder sub - groove at the ground contact edge satisfy the relationship of 0.2≦LL/PL≦0.5. pneumatic tires. The shoulder land portion and the center land portion are provided on the tread surface with narrower groove widths and shallower groove depths than the main grooves and the sub grooves to form narrow shallow grooves penetrating through the blocks. The pneumatic tire according to any one of claims 1 to 11 . 13. The pneumatic tire according to claim 12 , wherein the shallow groove has at least two bends.

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