JP2020050225A - tire - Google Patents

Abstract

To provide a tire in which biting of stones in the main groove thereof is restrained.SOLUTION: An objective tire includes on a tread part 2: a main groove 3; a first block row B1 adjacent to a first tread end 2a side of the main groove 3; and a second block row B2 adjacent to a second tread end 2b side. The main groove 3 expresses a zigzag shape including alternately a first apex P1 protruding at the first tread end 2a side, and a second apex P2 protruding at the second tread end 2b side. In a first block b1 included in the first block row B1, a first chamfering part M1 which extends from the vicinity of the second apex P2 to a first lateral groove Y1 located at the side of a first direction S1 in a tire circumferential direction is formed at a corner part formed by a tread and the flank of a main groove 3 side. In a second block b2 included in the second block row, a second chamfering part M2 which extends from the vicinity of the first apex P1 to a second lateral groove Y2 located at the side of the first direction S1 is formed at the corner part formed by the tread and the flank of the main groove 3 side. The first and second chamfering parts are arranged so as not to face each other in a tire axial direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tire, and more particularly, to a tire that can prevent stones from being caught in a main groove provided in a tread portion.

  Patent Literature 1 below discloses a tread portion in which a main groove extending in a zigzag shape in the tire circumferential direction, a lateral groove extending from the top of the zigzag of the main groove to both sides in the tire axial direction, and a block divided by these grooves. Has been proposed.

JP 2018-52351 A

  In a tire as disclosed in Patent Literature 1, stones tend to enter into the main grooves during running, and so-called stone biting that is held as it is tends to occur. There is a problem that the stones held in the main groove are gradually pushed to the groove bottom side due to the ground pressure during traveling, thereby causing damage such as cracks to the groove bottom portion.

  The present invention has been devised in view of the above situation, and it is possible to suppress the stone biting into the main groove, desirably, it is possible to suppress the stone biting without lowering the uneven wear resistance. The main purpose is to provide a comfortable tire.

  The present invention is a tire having a tread portion defined between a first tread end and a second tread end, the main groove extending continuously in a tire circumferential direction, and the first tread end of the main groove. A first block row adjacent to the first tread end side and a second block row adjacent to the second groove side of the main groove, wherein the main groove has a plurality of first blocks protruding toward the first tread end side. A zigzag shape alternately including a top portion and a plurality of second top portions projecting toward the second tread end side, wherein the first block row is connected to the first top portion and extends toward the first tread end side. A plurality of first blocks divided by a first lateral groove are included. In the plurality of first blocks, a corner portion formed by a tread surface and a side surface on the main groove side includes a second portion in a tire circumferential direction from near the second top portion. Extends to the first lateral groove located on the side in one direction One chamfered portion is formed, and the second block row includes a plurality of second blocks connected to the second top portion and separated by a second lateral groove extending toward the second tread end, and the plurality of second blocks are formed. In the corner portion formed by the tread surface and the side surface on the side of the main groove, a second chamfered portion extending from the vicinity of the first top to the second lateral groove located on the side in the first direction is provided, The chamfered portion and the second chamfered portion are arranged so as not to face each other in the tire axial direction.

  In another aspect of the present invention, the first chamfered portion and the second chamfered portion may be alternately arranged in a tire circumferential direction.

  In another aspect of the present invention, the corner portion of the first block is configured not to be chamfered from the vicinity of the second top portion to the first lateral groove located on the side in the tire circumferential direction in the second direction. The corner of the second block may not be chamfered from the vicinity of the first top to the second lateral groove located on the side in the second direction.

  In another aspect of the present invention, the first chamfer may gradually increase in chamfer width as the distance from the second apex increases, and the second chamfer may increase the chamfer width as the distance from the first apex increases. It may be increased gradually.

  In another aspect of the present invention, the first chamfered portion may have a chamfering height that gradually increases as the distance from the vicinity of the second apex increases, and the second chamfered portion increases a chamfering height as the distance from the vicinity of the first apex increases. May gradually increase.

  In another aspect of the present invention, the maximum value of the chamfered height in the first chamfered portion and the second chamfered portion may be 80% or more of the maximum groove depth of the main groove.

  In another aspect of the present invention, a rotation direction of the tread portion is determined, and the first direction may coincide with the rotation direction.

  In another aspect of the present invention, the first lateral groove includes a first groove wall and a second groove wall facing each other via a groove bottom, and the first groove wall and the second groove wall are arranged in a tire radial direction. The angle of the first groove wall with respect to the tread normal is larger than the angle θ2 of the second groove wall with respect to the tread normal, and the first groove is inclined outward. The wall may be configured to be connected to the first chamfer.

  In another aspect of the present invention, the second lateral groove includes a first groove wall and a second groove wall facing each other via a groove bottom, and the first groove wall and the second groove wall are arranged in a tire radial direction. The first groove wall has an angle θ1 with respect to the tread normal, which is larger than the angle θ2 of the second groove wall with the tread normal, and the second groove has The wall may be configured to be connected to the second chamfer.

  In another aspect of the present invention, the angle difference θ1−θ2 may be 7 to 17 degrees.

  In another aspect of the present invention, the first lateral groove may have a groove opening angle of 25 degrees or more.

  In another aspect of the present invention, a third groove wall is connected to the inside of the first groove wall in the tire radial direction, and an angle θ3 of the third groove wall with respect to a tread normal is set to be equal to the first groove wall. The wall may be configured to be smaller than the angle θ1.

  In another aspect of the present invention, the first block is disposed closer to the tire equator than the second block, and the length of the first chamfered portion in the tire circumferential direction is the tire of the second chamfered portion. It may be configured to be longer than the length in the circumferential direction.

  In another aspect of the present invention, the tread surface corner of the tread surface of the first block defined by the main groove and the first lateral groove located on the side in the second circumferential direction of the tire may be rounded. Preferably, in the tread surface of the second block, a tread corner portion defined by the main groove and the second lateral groove located on the side in the second direction is angular.

  In another aspect of the present invention, the tread surface of the first block includes a first vertical edge extending in a tire circumferential direction, and the tread surface is provided with a first narrow groove, and the first narrow groove is And a V-shape extending from the first end to the second end, and both the first end and the second end may be configured to open at the first vertical edge.

  In another aspect of the present invention, the first end or the second end of the first narrow groove may be configured to open at the first chamfer.

  In another aspect of the present invention, the tread surface of the second block includes a second vertical edge extending in a tire circumferential direction, wherein the second block is provided with a second narrow groove, The groove may be V-shaped in a horizontal direction extending from a third end to a fourth end, and both the third end and the fourth end may be configured to open at the second vertical edge.

  In another aspect of the present invention, the third end or the fourth end of the second narrow groove may be configured to open at the second chamfer.

  The tire of the present invention includes a main groove extending continuously in the tire circumferential direction, a first block row adjacent to a first tread end side of the main groove, and a second block row adjacent to a second tread end side of the main groove. And a block sequence. The main groove is formed in a zigzag shape including a plurality of first peaks projecting toward the first tread end and a plurality of second peaks projecting toward the second tread end.

  The first block row includes a plurality of first blocks separated by a first lateral groove extending to the first top and extending toward the first tread end. In the plurality of first blocks, a corner portion formed by a tread surface and a side surface on the side of the main groove has a first portion extending from the vicinity of the second top portion to the first lateral groove located on a first circumferential side in a tire circumferential direction. A chamfer is formed. The second block row includes a plurality of second blocks divided by a second lateral groove extending to the second top and extending toward the second tread end. In the plurality of second blocks, a corner formed by the tread surface and the side surface on the main groove side has a second chamfered portion extending from near the first top to the second lateral groove located on the side in the first direction. Provided. The first chamfered portion and the second chamfered portion are arranged so as not to face each other in the tire axial direction.

  Therefore, the tread side of the main groove is largely opened by the first chamfered portion and the second chamfered portion. Therefore, even when a stone enters the main groove, the stone can be easily discharged from the first chamfered portion and the second chamfered portion.

  In addition, in the vicinity of the first chamfered portion and the second chamfered portion of the tread, wear tends to be concentrated, but in the present invention, the first chamfered portion and the second chamfered portion are mutually separated in the tire axial direction. Since they are arranged so as not to face each other, it is possible to suppress the concentration of wear at a specific location, and to suppress the deterioration of uneven wear resistance.

It is a development view of a tread part of a tire of one embodiment of the present invention. It is the elements on larger scale of FIG. It is a perspective view showing one embodiment of a 1st block. It is a perspective view showing one embodiment of a 2nd block. FIG. 3 is a sectional view taken along line AA of FIG. 2. It is an enlarged plan view of the tread of the 1st block.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a development view of a tread portion 2 of a tire 1 showing one embodiment of the present invention. FIG. 2 is an enlarged view of the main part. The tire 1 of the present embodiment is configured as a pneumatic tire, and is particularly preferably implemented as a heavy-duty tire that is likely to be caught by a stone when subjected to a large contact pressure. In another aspect of the present invention, tire 1 may be implemented as a non-pneumatic tire or the like.

  As shown in FIG. 1, the tread portion 2 is defined between a first tread end 2a and a second tread end 2b. The tread portion 2 has a tread pattern formed by various grooves. In the present embodiment, the pattern between the tire equator C and the first tread end 2a is substantially line-symmetric with the pattern between the tire equator C and the second tread end 2b. They are arranged so as to be shifted by a half pitch in the tire circumferential direction.

  The first tread end 2a and the second tread end 2b are specified as the outermost contact positions in the tire axial direction on the contact surface when the tire 1 is in the normal load state.

  In the present specification, the normal load state is a state in which the tire 1 is mounted on a normal rim (not shown) at a normal internal pressure, and a normal load is applied to ground the tire 1 on a plane at a camber angle of 0 °.

  In the present specification, the “regular rim” is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, “standard rim” for JATMA, and “standard rim” for TRA "Design Rim", or "Measuring Rim" for ETRTO.

  In the present specification, the “normal internal pressure” is an air pressure defined for each tire in a standard system including a standard on which the tire is based, and is “maximum air pressure” for JATMA, and “highest air pressure” for TRA. The maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" is "INFLATION PRESSURE" for ETRTO.

  In the present specification, the “regular load” is a load defined for each tire in the standard system including the standard on which the tire is based, and in JATMA, “maximum load capacity” or TRA For example, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and for ETRTO, "LOAD CAPACITY".

  In this specification, unless otherwise specified, dimensions and the like of each part of the tire are values measured in a normal state. In this specification, the "normal state" is a state in which the tire is mounted on the normal rim at the normal internal pressure but no load is applied.

  The tread portion 2 includes a main groove 3 extending continuously in the tire circumferential direction, a first block row B1 adjacent to the first tread end 2a side of the main groove 3, and a main groove 3 adjacent to the second tread end 2b side of the main groove 3. And an adjacent second block row B2.

  The main groove 3 of the present embodiment is disposed, for example, near the tire equator C, and forms, for example, a crown main groove. The main groove 3 extends in a zigzag shape in the tire circumferential direction. More specifically, the main groove 3 alternately includes a plurality of first peaks P1 projecting toward the first tread end 2a and a plurality of second peaks P2 projecting toward the second tread end 2b. It is zigzag. Each apex P1 and P2 is specified on a groove center line, for example, as shown in FIG. In the main groove 3 of the present embodiment, linear groove elements that are inclined in opposite directions are alternately arranged. In another embodiment, the main groove 3 may have a zigzag shape that smoothly curves.

  The main groove 3 preferably has, for example, a groove width of 2.0% to 4.0% of the tread width TW (shown in FIG. 1). In the case of a heavy load pneumatic tire, the main groove 3 preferably has a groove depth of, for example, 20 to 25 mm. Such a main groove 3 can improve the steering stability on a dry road surface and the wet performance in a well-balanced manner.

  The first block row B1 is disposed, for example, closest to the tire equator C. The first block row B1 includes a plurality of first blocks b1 divided by the first horizontal groove Y1. In the present embodiment, these first blocks b1 constitute a crown block.

  The first lateral groove Y1 continues to the first top P1 and extends toward the first tread end 2a. The first lateral groove Y1 of the present embodiment forms a crown lateral groove extending in the tire axial direction. It is desirable that the first lateral groove Y1 is inclined at a small angle, for example, 10 to 20 ° with respect to the tire axial direction.

  FIG. 3 is an enlarged perspective view of the first block b1. As shown in FIG. 3, the first block b1 of the present embodiment has, for example, a hexagonal tread surface 5. More specifically, the tread 5 has first vertical edges E1 and E1 on both sides in the tire axial direction, and each first vertical edge E1 has a first convex portion 5a protruding outward in the width direction of the block. Including. Further, a first chamfer M1 is formed in the first block b1.

  The first chamfered portion M1 is provided, for example, at a corner formed by the tread surface 5 of the first block b1 and the side surface 6 on the main groove 3 side of the first block b1. Further, the first chamfered portion M1 extends from the vicinity of the second top portion P2 of the main groove 3 of the corner portion to the first lateral groove Y1 located on the side of the tire circumferential direction in the first direction S1.

  Here, the term "near" means that one end of the first chamfered portion M1 is provided close to the position of the second apex P2 in the tire circumferential direction in the tire circumferential direction. The embodiment in which one end of the portion M1 completely coincides with the second top portion P2 is included. Further, as shown in FIG. 2, when one end of the first chamfered portion M1 and the second top portion P2 are separated from each other in the tire circumferential direction, the distance D in the tire circumferential direction is, for example, the first chamfered portion. It is desirable that the maximum length bL of the first block b1 provided with M1 in the tire circumferential direction be 15% or less.

  In the corner portion of the first block b1, the remaining portion other than the first chamfered portion M1 is a non-chamfered portion. That is, from the vicinity of the second top P2, the first lateral groove Y1 located on the side in the second direction S2 which is the direction opposite to the tire circumferential direction from the first direction S1 is not chamfered, and the non-chamfered portion Have been. In the non-chamfered portion, the side surface 6 of the first block b1 extends so as to be inclined at a substantially constant angle from the tread surface 5 to the groove bottom of the main groove 3.

  The second block row B2 constitutes, for example, a middle block row arranged outside the first block row B1 in the tire axial direction. The second block row B2 includes a plurality of second blocks b2 divided by the second horizontal groove Y2. In the present embodiment, these second blocks b2 constitute a middle block.

  The second lateral groove Y2 communicates with the second top P2 and extends toward the second tread end 2b. The second lateral groove Y2 of the present embodiment forms a middle lateral groove extending in the tire axial direction. The second lateral groove Y2 of the present embodiment is desirably inclined at a small angle, for example, 10 to 20 ° with respect to the tire axial direction. It is desirable that the second lateral groove Y2 is inclined in the same direction as the first lateral groove Y1.

  FIG. 4 is an enlarged perspective view of the second block b2. As shown in FIG. 4, each of the second blocks b2 has, for example, a hexagonal tread surface 7. More specifically, the tread 7 has second vertical edges E2 on both sides in the tire axial direction, and each second vertical edge E2 includes a second convex portion 7a that protrudes outward in the width direction of the block.

  Further, a second chamfer M2 is formed in each of the second blocks b2.

  The second chamfered portion M2 is provided, for example, at a corner formed by the tread surface 7 of the second block b2 and the side surface 8 of the second block b2 on the main groove 3 side. The second chamfer M2 extends from the vicinity of the first top P1 of the main groove 3 to a second lateral groove Y2 located on the side of the tire circumferential direction in the first direction S1. The above “neighborhood” must be understood similarly to the definition described in the first block b1.

  In the corner portion of the second block b2, the portion from the vicinity of the first top portion P1 to the second lateral groove Y2 located on the side in the second direction S2 is not chamfered and is a non-chamfered portion. In the non-chamfered portion, the side surface 8 of the second block b2 is inclined at a substantially constant angle from the tread surface 7 to the groove bottom of the main groove 3.

  Therefore, in the tire 1 of the present embodiment, the tread side of the main groove 3 is partially largely opened by the first chamfered portion M1 and the second chamfered portion M2. For this reason, even if a stone enters the main groove 3, the stone is easily discharged from the position of the first chamfered portion M1 or the second chamfered portion M2.

  On the other hand, the first chamfered portion M1 and the second chamfered portion M2 of the first block b1 and the second block b2 have different stiffness compared to the non-chamfered portions of the first block b1 and the second block b2, and the vicinity thereof. Wear tends to concentrate. In view of this point, in the present embodiment, the first chamfered portion M1 and the second chamfered portion M2 are arranged so as not to face each other in the tire axial direction. That is, when each of the first chamfered portions M1 is projected on the side surface 8 of the second block b2 along the tire axial direction, none of the projected regions overlaps with the second chamfered portion M2.

  Therefore, since the first chamfered portion M1 and the second chamfered portion M2 are dispersedly arranged in the tire circumferential direction, uneven wear resistance is improved, and stone biting can be suppressed in a wide range of the main groove 3. In a preferred embodiment, as shown in FIG. 1, the first chamfered portions M1 and the second chamfered portions M2 are preferably arranged alternately in the tire circumferential direction. Accordingly, the non-chamfered portion of the first block b1 faces the second chamfered portion M2 of the second block b2 in the tire axial direction. In addition, the non-chamfered portion of the second block b2 faces the first chamfered portion M1 of the first block b1 in the tire axial direction.

  In addition, the first convex portion 5a of the first block b1 located near the second top portion P2 of the main groove 3 generally has a large rubber volume and tends to have high compression rigidity in the tire axial direction. Therefore, in the vicinity of the second top portion P2 of the main groove 3, a stone is easily sandwiched. However, the first chamfer M1 extends from the vicinity of the second top P2 to the first lateral groove Y1. For this reason, the stone caught near the second top portion P2 of the main groove 3 can be gradually pushed out to the first lateral groove Y1 and discharged by the compression deformation of the main groove 3 when the tire is in contact with the ground.

  Similarly, the second convex portion 7a of the second block b2 located near the first top P1 of the main groove 3 also has a large rubber volume and tends to have high compression rigidity in the tire axial direction. Therefore, the stone is likely to be caught near the first top P1 of the main groove 3 as well. However, since the second chamfered portion M2 also extends from the vicinity of the first top portion P1 to the second lateral groove Y2, stones sandwiched near the first top portion P1 can be gradually pushed out to the second lateral groove Y2 and discharged.

  As shown in FIG. 2, in the present embodiment, the chamfer width W1 in the tire axial direction of the first chamfered portion M1 gradually increases as the distance from the second top portion P2 increases. Similarly, the chamfer width W2 of the second chamfered portion M2 in the tire axial direction gradually increases as the distance from the first top portion P1 increases. Therefore, the groove width of the tread surfaces 5 and 7 of the main groove 3 gradually increases toward the first top P1 in the first chamfered portion M1, and gradually increases toward the second top P2 in the second chamfered portion M2. According to such an aspect, the stone that has bitten into the main groove 3 moves to the larger one of the chamfer widths W1 and W2 with less resistance in each of the chamfered portions M1 and M2, and further enhances the stone discharging action. Can be promoted.

  In a preferred embodiment, in the first chamfered portion M1 and the second chamfered portion M2, the maximum value of the chamfered widths W1 and W2 (the maximum value measured along the tire axial direction) is the maximum value in the non-chamfered portion of the main groove 3. It is 15% or more of the small width Ws, more preferably 20% or more, and further preferably 30% or more. Thereby, the stone biting performance can be further improved.

  As shown in FIG. 3, in the present embodiment, the chamfering height h1 of the first chamfered portion M1 gradually increases as the distance from the vicinity of the second top portion P2 increases. Similarly, as shown in FIG. 4, the chamfering height h2 of the second chamfered portion M2 gradually increases as the distance from the vicinity of the first top portion P1 increases. According to such an embodiment, the stones that have caught in the main groove 3 are more likely to move to the lower chamfer heights h1 and h2 with less resistance, further promoting the stone discharging action. In addition, this aspect can further promote the above-described stone discharging action by being combined with an aspect in which the chamfer widths W1 and W2 gradually increase.

  In a preferred embodiment, in the first chamfered portion M1 and the second chamfered portion M2, the maximum value of the chamfered heights h1 and h2 is 80% or more of the maximum groove depth GD of the main groove 3 (shown in FIG. 3). . Thereby, the stone biting performance can be further improved.

  The rotation direction of the tread portion 2 may be determined. This rotation direction is indicated by, for example, an arrow or a letter on a sidewall portion (not shown) of the tire 1. In this case, it is desirable that the first direction S1 coincides with the rotation direction of the tire 1. That is, in the first block b1 and the second block b2, it is desirable that the first chamfered portion M1 and the second chamfered portion M2 are formed only on the first-come-first-served side in the rotation direction. Thereby, the stone biting performance is further improved. Here, as an example, a case where a stone is sandwiched between three blocks of two first blocks b1 and one second block b2 (at the first top P1) while the tire 1 is rotating in the first direction S1. Think. When the rotation of the tire 1 advances and one of the three blocks, the first block b1, separates from the road surface, the stone initially sandwiched by the three blocks is mainly composed of one first block b1 and one first block b1. It is supported by two blocks of two blocks b2. At this time, the stone is relatively easy to move due to a change in holding force, bending deformation of the tread portion 2, and the like. Here, if the first chamfered portion M1 is provided at the end of the first block b1 that is still in contact with the ground, the movement of the stone is further promoted, and the stone is easily discharged from the main groove 3.

  In the present embodiment, the first lateral groove Y1 and the second lateral groove Y2 have basically the same configuration. Hereinafter, the first lateral groove Y1 will be described as an example, but the content is also applied to the second lateral groove Y2.

  FIG. 5 is a cross-sectional view taken along line AA of FIG. 2 as a cross-section of the first horizontal groove Y1. As shown in FIG. 5, the first lateral groove Y1 includes a groove bottom 10 and a first groove wall 11 and a second groove wall 12 facing each other via the groove bottom. In the present embodiment, the first groove wall 11 is located on the second direction S2 side in the tire circumferential direction, and the second groove wall 12 is located on the first direction S1 in the tire circumferential direction. Therefore, the first groove wall 11 constitutes a wall surface on the first arrival side in the rotation direction of the first block b1, and is connected to the first chamfered portion M1.

  The first groove wall 11 and the second groove wall 12 are inclined such that the groove width increases outward in the tire radial direction. In a preferred embodiment, the groove opening angle α of the first lateral groove Y1 is formed sufficiently large, for example, 25 degrees or more. Thereby, stone biting in the first lateral groove Y1 is suppressed. The upper limit of the groove opening angle α is, for example, about 45 degrees.

  In a preferred embodiment, the angle θ1 of the first groove wall 11 with respect to the tread normal N is larger than the angle θ2 of the second groove wall 12 with respect to the tread normal N. This increases the shear rigidity of the first-coming-side portion of the first block b1, suppresses a decrease in rigidity due to the provision of the first chamfered portion M1, and helps to suppress uneven wear there. In a particularly preferred embodiment, the angle difference θ1−θ2 is 7 to 17 degrees.

  In a preferred embodiment, a third groove wall 13 is connected to the inside of the first groove wall 11 in the tire radial direction. The angle θ3 of the third groove wall 13 with respect to the tread normal N is smaller than the angle θ1 of the first groove wall 11. In the present embodiment, the angle θ3 of the third groove wall 13 is substantially equal to the angle θ2 of the second groove wall 12. Such a third groove wall 13 reinforces the root portion of the first block b1, and further enhances the uneven wear resistance performance of the first block b1 at the first-coming-side portion.

  In the present embodiment, the first block b1 is disposed closer to the tire equator C than the second block b2. Therefore, the first block b1 tends to receive a higher ground pressure than the second block b2. For this reason, if the maximum length of the first chamfered portion M1 in the tire circumferential direction is larger than the maximum length of the second chamfered portion M2 in the tire circumferential direction, the stone biting performance is further improved.

  As shown in FIGS. 2 and 3, in a preferred embodiment, the tread surface 5 of the first block b1 is a tread surface defined by the main groove 3 and the first lateral groove Y1 located on the side of the tire circumferential direction in the second direction S2. The corner portion 15 (that is, the rear arrival side corner portion) is rounded. On the other hand, as shown in FIG. 2 or FIG. 4, the tread surface 7 of the second block b2 has a tread surface corner portion 16 defined by the main groove 3 and the second lateral groove Y2 located on the side in the second direction S2 (ie, , A corner portion on the rear arrival side) is more angular than the tread corner portion. Thereby, stone biting performance and uneven wear resistance are further improved.

[First narrow groove]
In a preferred mode, the first narrow groove 21 is provided in the first block b1. In the present embodiment, two first narrow grooves 21 are provided. These two first narrow grooves 21 are arranged without crossing each other.

  Each of the first narrow grooves 21 has a laterally V-shape extending from the first end 21a to the second end 21b. Both the first end 21a and the second end 21b are open at one first vertical edge E1 of the tread surface 5. That is, both the first end 21a and the second end 21b of the first narrow groove 21 on the right side are opened at the first vertical edge E1 on the right side, and the first end 21a and the second end of the first narrow groove 21 on the left side. 21b are open at the left first vertical edge E1.

  When the block is grounded, the first narrow groove 21 easily elastically deforms the block piece 24 surrounded by the first narrow groove 21 and the first vertical edge E1, and thus moves the stone in the main groove 3 or Help discharge. In addition, the elastic deformation can reduce the contact pressure on the first arrival side and the second arrival side in the rotation direction of the first block b1, and can effectively suppress the heel-and-toe wear of the first block b1. Further, since the first narrow groove 21 enhances the frictional force on a wet road surface by its edge, excellent wet running performance can be obtained.

  In a preferred embodiment, the first end 21a of the first narrow groove 21 opens at the first chamfer M1. Thus, when the first block b1 touches the ground, the vicinity of the first chamfered portion M1 is more flexibly deformed, and the stone discharging action there is further enhanced.

  FIG. 6 shows an enlarged view of the tread surface 5 of the first block b1. In a particularly preferred embodiment, the first end 21a of the first narrow groove 21 is arranged on the first direction S1 side of the first top P1, and the second end 21b is arranged on the second direction S2 side of the first top P1. That is, the first narrow groove 21 is arranged so as to surround the first convex portion 5a of the first block b1. This makes it easy to deform the vicinity of the first convex portion 5a of the first block b1 having high compression rigidity, and further suppresses stone biting there.

  Note that the “V-shape” does not intend the V-shape of the alphabet itself, but extends from the first end 21a on the first vertical edge E1 and curves in the tread surface 5 of the first block b1. Again, this is a typical concept of reaching the second end 21b on the first vertical edge E1. Therefore, the V-shape should be understood to include not only the aspect of the present embodiment but also various shapes such as a shape close to a U-shape and a semicircle.

  The first narrow groove 21 includes, for example, a first inclined element 26 and a second inclined element 27. The first inclined element 26 extends, for example, from the first end 21a in an inclined manner with respect to the tire axial direction. The second inclined element 27 extends from the second end 21b in a direction opposite to the first inclined element 26 with respect to the tire axial direction. The first narrow groove 21 further has a connecting portion 28 that smoothly connects the first inclined element 26 and the second inclined element 27. The connection portion 28 is, for example, in a smooth arc shape.

  Preferably, each of the first tilt element 26 and the second tilt element 27 extends linearly. The angle β between the first tilt element 26 and the second tilt element 27 is desirably 70 ° or more, more desirably 80 ° or more, desirably 140 ° or less, more desirably 130 ° or less. Such first narrow grooves 21 further improve the resistance to biting stones and also improve the resistance to uneven wear.

  The connection portion 28 is curved, for example, just before an intermediate position of the tread surface 5 in the tire axial direction. The distance L in the tire axial direction from the outermost position in the block width direction of the first vertical edge E1 to the connection portion 28 is 0.10 to 0.40 times the maximum width BW of the first block b1 in the tire axial direction. It is desirable to have. Such a first narrow groove 21 can exert the above-described effects while suppressing an excessive decrease in rigidity of the first block b1.

  The minimum distance Ls in the tire circumferential direction from the first top P1 to the first end 21a of the first narrow groove 21 is, for example, 0 of the distance 21L in the tire circumferential direction between the first end 21a and the second end 21b. 0.25 to 0.75 times. Thereby, when the first block b1 is in contact with the ground, the vicinity of the first convex portion is smoothly deformed, and the above-described effect can be significantly exerted.

  In the first block b1 of the present embodiment, two first narrow grooves 21 are provided, but only one may be provided. In this case, it is desirable that the first narrow groove 21 is arranged on the side of the two first vertical edges E1 where the first chamfered portion M1 is provided.

[Second narrow groove]
In a preferred embodiment, the second narrow groove 22 is provided in the second block b2. In the present embodiment, two second narrow grooves 22 are provided. These two second narrow grooves 22 are arranged without crossing each other.

  Each of the second narrow grooves 22 has a V-shaped lateral direction extending from the third end 22a to the fourth end 22b. The third end 22a and the fourth end 22b are both open at one second vertical edge E2 of the tread surface 7. That is, the third end 22a and the fourth end 22b of the second narrow groove 22 on the right side are both opened at the second vertical edge E2 on the right side, and the third end 22a and the fourth end of the second narrow groove 22 on the left side. Each of the openings 22b is opened at the second vertical edge E2 on the left side.

  The second narrow groove 22 has the same configuration as the first narrow groove 21. Therefore, the second narrow groove 22 of the present embodiment has the same operation as the first narrow groove 21.

  In order to exhibit the above-mentioned effects in a well-balanced manner, it is desirable that each of the first narrow groove 21 and the second narrow groove 22 has a groove width of, for example, 0.5 to 3.0 mm. The first narrow groove 21 and the second narrow groove 22 each preferably have a groove depth of, for example, 2.5% to 14%, and particularly preferably about 0.5 to 3.5 mm. .

  As shown in FIG. 1, in a preferred embodiment, on both sides of the main groove 3, the first narrow groove 21 and the second narrow groove 22 extend in a zigzag manner in the tire circumferential direction via the main groove 3. It is desirable to arrange them smoothly and continuously. In such an embodiment, in addition to the first chamfered portion M1 and the second chamfered portion M2, the first narrow groove 21 and the second narrow groove 22 arranged in a zigzag manner so as to cross the main groove 3 make the main groove 3 Is suppressed in a wider range in the tire circumferential direction.

  For example, a third block row B3 is formed outside the second block row B2 in the tire axial direction. The third block row B3 forms a land portion of the tread portion 2 that is the outermost portion in the tire axial direction.

  The third block row B3 includes a plurality of third blocks b3 divided by the third lateral groove Y3. In the present embodiment, these third blocks b3 constitute a shoulder block. The third lateral groove Y3 is desirably inclined at a small angle with respect to the tire axial direction, for example, 5 to 10 °. The angle of the third lateral groove Y3 is configured to be smaller than the angle of the first lateral groove Y1 and the second lateral groove Y2.

  It is desirable that the third lateral groove Y3 has a groove width larger than, for example, the first lateral groove Y1 and the second lateral groove Y2. On the other hand, it is desirable that the third lateral groove Y3 has a groove depth smaller than, for example, the first lateral groove Y1 and the second lateral groove Y2. Thereby, the shear rigidity of the third block b3 in the tire circumferential direction can be increased without impairing the drainage performance, and thus the steering stability can be improved.

  For example, a third narrow groove 30 may be provided in the third block b3. The third narrow groove 30 extends, for example, along the third lateral groove Y3. In a preferred embodiment, the third lateral groove Y3 crosses the third block b3 so as to bisect the third block in the tire circumferential direction. Such third lateral groove Y3 maintains the rigidity of the third block b3 high, and enhances steering stability and uneven wear resistance on dry road surfaces. The third lateral groove Y3 desirably has the same groove width and groove depth as the first narrow groove 21 and the second narrow groove 22.

  As described above, the pneumatic tire according to one embodiment of the present invention has been described in detail. However, the present invention is not limited to the above-described specific embodiment, and can be implemented in various modes.

  A 315 / 80R22.5 heavy duty pneumatic tire having the basic pattern of FIG. 1 was prototyped based on the specifications of Table 1 (Examples 1 to 4, Comparative Examples 1 and 2).

  The tire of Comparative Example 1 differs from the pattern of FIG. 1 in that the first chamfered portion and the second chamfered portion are not provided.

  In the tire of Comparative Example 2, the first chamfered portion and the second chamfered portion extend continuously between the first lateral grooves and between the second lateral grooves, respectively. It differs from the pattern of FIG. 1 in that it faces each other in the axial direction.

  The embodiments are all based on the pattern of FIG. The first and second narrow grooves in FIG. 1 are provided only in the fourth embodiment.

Then, the stone bite resistance and uneven wear resistance of each tire were tested. The common specifications and test methods for each test tire are as follows.
[Main groove]
Width Ws (minimum width at the non-chamfered portion): 7 mm
Depth GD: 24mm
[First lateral groove and second lateral groove]
Groove width: 11mm
Angle θ1 of first groove wall: 19 degrees Angle θ2 of second groove wall: 6 degrees Open angle α: 25 degrees [first chamfered portion and second chamfered portion]
Chamfer height h1: Gradual increase from 30% to 80% with respect to main groove depth GD Chamfer height h2: Gradually increase from 30% to 80% with respect to main groove depth GD

[Stone resistance performance]
Each test tire was mounted on a vehicle, and the vehicle was driven on a gravel road for 20 km, and the number of pebbles held in the main groove extending between the first block and the second block was measured. The results are in exponential notation, with Example 1 adjusted to 100. The higher the value, the better the performance.

[Partial wear resistance]
After each test tire was mounted on the vehicle and the vehicle traveled on a dry road for a certain distance, the wear difference between the first and second blocks in the rotational direction was measured for each of the first and second blocks, and the average value thereof was obtained. Was done. The results are in exponential notation, with Example 1 adjusted to 100. The higher the value, the better the performance.
The results of the test are shown in Table 1.

  As a result of the test, it was confirmed that the tires of the examples have improved stone bite resistance and uneven wear resistance.

Reference Signs List 1 tire 2 tread portion 2a first tread end 2b second tread end 3 main groove 5 tread surface of first block 6 side surface of first block 7 tread surface of second block 8 side surface B1 of second block B1 first block row B2 second Block row M1 First chamfered portion M2 Second chamfered portion P1 First vertex P2 Second vertex S1 First direction S2 Second direction Y1 First lateral groove Y2 Second lateral groove b1 First block b2 Second block

Claims (18)

A tire having a tread portion defined between a first tread end and a second tread end,
A main groove extending continuously in the tire circumferential direction, a first block row adjacent to the first tread end side of the main groove, and a second block row adjacent to the second tread end side of the main groove. Including
The main groove has a zigzag shape including a plurality of first peaks projecting toward the first tread end side and a plurality of second peaks projecting toward the second tread end side alternately,
The first block row includes a plurality of first blocks divided by a first lateral groove extending to the first top and extending toward the first tread end.
In the plurality of first blocks, a corner portion formed by a tread surface and a side surface on the side of the main groove has a first portion extending from the vicinity of the second top portion to the first lateral groove located on a first circumferential side in a tire circumferential direction. A chamfer is formed,
The second block row includes a plurality of second blocks separated by a second lateral groove extending to the second top portion and extending toward the second tread end.
In the plurality of second blocks, a corner formed by the tread surface and the side surface on the main groove side has a second chamfered portion extending from near the first top to the second lateral groove located on the side in the first direction. Provided,
The first chamfered portion and the second chamfered portion are arranged so as not to face each other in the tire axial direction.
tire.   The tire according to claim 1, wherein the first chamfered portion and the second chamfered portion are alternately arranged in a tire circumferential direction.   The corner portion of the first block is not chamfered from near the second top to the first lateral groove located on the side in the second circumferential direction of the tire, and the corner portion of the second block is not chamfered. 3. The tire according to claim 1, wherein the tire is not chamfered from the vicinity of the first top to the second lateral groove located on the side in the second direction. 4.   4. The chamfered width of the first chamfered portion gradually increases as the distance from the second top portion increases, and the chamfering width of the second chamfered portion gradually increases as the distance from the first top portion increases. The tire described in the above.   The chamfer height of the first chamfer gradually increases as the distance from the vicinity of the second apex increases, and the chamfer height of the second chamfer gradually increases as the distance from the vicinity of the first apex increases. The tire according to any of the above.   The tire according to any one of claims 1 to 5, wherein a maximum value of the chamfered height in the first chamfered portion and the second chamfered portion is 80% or more of a maximum groove depth of the main groove.   The tire according to any one of claims 1 to 6, wherein a rotation direction of the tread portion is determined, and the first direction coincides with the rotation direction. The first lateral groove includes a first groove wall and a second groove wall facing each other via a groove bottom,
The first groove wall and the second groove wall are inclined in a direction in which a groove width increases outward in a tire radial direction,
The angle θ1 of the first groove wall with respect to the tread normal is larger than the angle θ2 of the second groove wall with respect to the tread normal,
The tire according to any one of claims 1 to 7, wherein the first groove wall is connected to the first chamfer. The second lateral groove includes a first groove wall and a second groove wall facing each other via a groove bottom,
The first groove wall and the second groove wall are inclined in a direction in which a groove width increases outward in a tire radial direction,
The angle θ1 of the first groove wall with respect to the tread normal is larger than the angle θ2 of the second groove wall with respect to the tread normal,
The tire according to claim 1, wherein the second groove wall is connected to the second chamfer.   The tire according to claim 8, wherein the angle difference θ1−θ2 is 7 to 17 degrees.   The tire according to any one of claims 8 to 10, wherein a groove opening angle of the first lateral groove is 25 degrees or more. A third groove wall is connected inward of the first groove wall in the tire radial direction,
The tire according to any one of claims 8 to 11, wherein an angle θ3 of the third groove wall with respect to a tread normal is smaller than the angle θ1 of the first groove wall. The first block is disposed closer to the tire equator than the second block,
The tire according to any one of claims 1 to 12, wherein a length of the first chamfered portion in the tire circumferential direction is larger than a length of the second chamfered portion in the tire circumferential direction. In the tread surface of the first block, a tread corner portion defined by the main groove and the first lateral groove located on a side in the second circumferential direction of the tire is rounded,
14. The tread surface of the second block, wherein a tread corner portion defined by the main groove and the second lateral groove located on the side in the second direction is angular. 15. tire. The tread surface of the first block includes a first vertical edge extending in a tire circumferential direction,
A first narrow groove is provided on the tread,
The first narrow groove has a V-shape extending sideways from a first end to a second end,
The tire according to any one of claims 1 to 14, wherein both the first end and the second end open at the first vertical edge.   The tire according to claim 15, wherein the first end or the second end of the first narrow groove is opened at the first chamfer. The tread of the second block includes a second vertical edge extending in a tire circumferential direction,
The second block is provided with a second narrow groove,
The second narrow groove has a V-shape that extends from the third end to the fourth end,
The tire according to any one of claims 1 to 16, wherein both the third end and the fourth end open at the second vertical edge.   The tire according to claim 17, wherein the third end or the fourth end of the second narrow groove is opened at the second chamfer.

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