JP2008126943A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control an eccentric wear of a block divided by a lug groove. <P>SOLUTION: By forming a depressed portion 26 on the kicking edge side of a tread surface of a shoulder block 22, ground contact pressure on the depressed portion 26 is reduced and deformation on the kicking edge side of the shoulder block 22 is restrained at the time of kicking out. This restrains the kicking edge of the shoulder block 22 from getting dragged into a road surface and eccentric abrasion (so-called heel-and-toe abrasion) in which the kicking edge side gets greatly worn relative to the stepping edge side. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire suitable for a construction vehicle having a lug groove on a tread.

A lug groove is generally formed in a tread of a pneumatic tire for a construction vehicle (see Patent Document 1).
JP 2000-233610 A

  In a pneumatic tire for construction vehicles, there is a problem in that uneven wear occurs in which the wear amount at the kicking end of the shoulder block becomes larger than the center of the block due to the thick tread gauge. Although such a wear form leads to a decrease in wear resistance performance and appearance, there has been no effective solution.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a pneumatic tire that can suppress uneven wear of blocks defined by lug grooves.

  The pneumatic tire according to claim 1 includes a plurality of lug grooves arranged at intervals in the tire circumferential direction on both sides in the tire width direction of the tread, and is positioned between the lug grooves adjacent to each other in the circumferential direction. In the tread surface of the land portion, a dent lower than the tread surface contacting the road surface and shallower than the lug groove is disposed adjacent to the lug groove.

Next, the operation of the pneumatic tire according to claim 1 will be described.
In particular, in a pneumatic tire for a super-large construction vehicle in recent years, in a pattern in which a plurality of lug grooves are formed at intervals on the tire circumferential direction on both sides in the tire width direction of the tread, the center region is more rigid than the tread shoulder region rigidity. Since the rigidity is very high, the difference in rigidity between the shoulder region and the center region becomes large, and uneven wear of the shoulder region becomes a problem.

  Specifically, this is uneven wear (so-called heel and toe wear) in which the kicking end side of the land portion is worn more than the stepping end side. As shown in FIG. 2A, this uneven wear occurs when the rectangular block 100 is separated from the road surface during driving, as shown in FIG. 2A, or when the rectangular block 100 is separated from the road surface 102 as shown in FIG. R direction), the kicking end side of the block 100 is deformed and dragged to the road surface 102 (arrow A), and the wear is promoted more than the central portion in the circumferential direction of the block 100. As a result of various experimental studies, the inventor has found that suppressing deformation of the block 100 at the kicking end side during kicking is effective in suppressing this wear.

  In the pneumatic tire according to claim 1, a depression that is lower than the tread surface that contacts the road surface and shallower than the lug groove is formed on the tread surface of the land portion formed on both sides in the tire width direction so as to contact the lug groove. As a result, the contact pressure of the portion where the dent is formed (near the circumferential end of the block) is reduced, deformation near the circumferential end of the block is suppressed, and drag on the road surface associated with the deformation is reduced, Uneven wear can be suppressed.

  The invention according to claim 2 is characterized in that, in the pneumatic tire according to claim 1, a rotation direction is specified, and the recess is formed only on a kicking end side of the land portion.

Next, the operation of the pneumatic tire according to claim 2 will be described.
When uneven wear occurs in the land due to the fact that the land near the kicking edge is dragged to the road surface, the ground pressure near the kicking end is reduced by forming a dent on the kicking edge side of the land. Uneven wear near the kicking end can be suppressed.

  According to a third aspect of the present invention, in the pneumatic tire according to the first aspect, the recess is formed on a kicking end side and a stepping end side of the land portion.

Next, the operation of the pneumatic tire according to claim 3 will be described.
Since the rotation direction of the pneumatic tire may be reversed due to rotation, the portion that has been the stepping-in end side until now may be the kicking-out end side. Therefore, when it is set as the specification which does not designate a rotation direction, it is preferable to form a dent in the kicking end side and stepping end side of a land part.
Also, depending on the use conditions, uneven wear may occur on the stepping end side. In such a case, it is preferable that uneven wear on the stepping end side can be suppressed.

  According to a fourth aspect of the present invention, in the pneumatic tire according to any one of the first to third aspects, the maximum depth of the recess is measured at a central position between the tire equatorial plane and the tread edge. It is set within a range of 2 to 7% of the groove depth of the lug groove.

Next, the operation of the pneumatic tire according to claim 4 will be described.
When the maximum depth of the dent is less than 2% of the groove depth of the lug groove measured at the center position between the tire equatorial plane and the tread edge, the effect of suppressing uneven wear cannot be obtained sufficiently. Decreases and deteriorates wear resistance.

  According to a fifth aspect of the present invention, in the pneumatic tire according to the fourth aspect, the position where the maximum depth of the recess is a position in contact with the lug groove, and the depth of the recess changes in the tire circumferential direction. It is characterized by that.

Next, the operation of the pneumatic tire according to claim 5 will be described.
When the uneven wear part does not have a certain depth when the land portion is viewed in the circumferential cross section, the depth of the dent is changed in the tire circumferential direction according to the uneven wear. Abrasion can be more effectively suppressed.

  A sixth aspect of the present invention is the pneumatic tire according to any one of the first to fifth aspects, wherein the recess has a tire circumferential length that is a center position between the tire equatorial plane and the tread end. It is set within a range of 10 to 40% of the circumferential length of the land portion.

Next, the operation of the pneumatic tire according to claim 6 will be described.
When the tire circumferential direction length of the dent is less than 10% of the circumferential length of the land portion at the center position between the tire equatorial plane and the tread end, the effect of suppressing uneven wear cannot be sufficiently obtained.

  When the tire circumferential length of the dent exceeds 40% of the circumferential length of the land portion at the center position between the tire equatorial plane and the tread edge, the dent is too wide and wear resistance is deteriorated.

  A seventh aspect of the present invention is the pneumatic tire according to any one of the first to sixth aspects, wherein the recess is located on the outer side in the tire width direction from the center position between the tire equatorial plane and the tread end. And it is arrange | positioned rather than the edge part of the belt with the widest width | variety at the tire equatorial plane side.

  Uneven wear tends to occur more on the tire equatorial plane side than the end of the widest belt on the outer side in the tire width direction than the center position between the tire equatorial plane and the tread end. Therefore, in accordance with the part where uneven wear occurs, the dent is arranged on the tire equatorial plane side of the widest belt and on the outer side in the tire width direction from the center position of the tire equatorial plane and the tread end. It is preferable.

  The invention according to claim 8 is the pneumatic tire according to any one of claims 1 to 7, wherein a thickness of the tread rubber constituting the tread is in a range of 60 to 200 mm. It is characterized by that.

Next, the operation of the pneumatic tire according to claim 8 will be described.
When the thickness of the tread rubber is less than 60 mm, the durability of the tread is insufficient when used for a construction vehicle. On the other hand, if the thickness of the tread rubber exceeds 200 mm, the heat generation durability deteriorates when used for construction vehicles.

  As described above, according to the pneumatic tire of the present invention, there is an excellent effect that uneven wear of a pattern having lug grooves on both sides in the tire width direction of the tread can be suppressed.

[First Embodiment]
Hereinafter, a first embodiment of a pneumatic tire of the present invention will be described with reference to the drawings. In FIG. 1, the pneumatic tire 10 according to the present embodiment has a rotational direction designated in the direction of arrow R, and the tread 12 has a circumferential narrow groove 14 extending along the tire circumferential direction on the tire equatorial plane CL. Main lug grooves 16 that are formed on both sides and extend outward in the tire width direction from the circumferential narrow groove 14 are formed at intervals in the tire circumferential direction on the outer side in the tire width direction of the circumferential narrow groove 14. .

In addition, it is preferable that the circumferential direction narrow groove 14 is arrange | positioned in the area | region of 25 to 50% of tread width TW centering on the tire equator surface CL.
The pneumatic tire 10 of the present embodiment has a novel tread pattern, and has a conventionally well-known structure (for example, a radial structure) with respect to the internal structure.

  In the present embodiment, hereinafter, a rib-shaped land portion between one circumferential narrow groove 14 and the other circumferential narrow groove 14 of the tread 12 is referred to as a central region land portion 18. In the central region land portion 18, sipe-shaped ultrafine center lug grooves 20 that cross in the tire width direction are provided at intervals in the tire circumferential direction to form a pseudo block row. The sipe-shaped ultra-fine center lug groove 20 is set to a groove width that is closed immediately below the load during rolling, and the groove depth is the same as that of the main lug groove 16.

  In the present embodiment, a land portion defined by the circumferential narrow groove 14 and the main lug groove 16 is referred to as a shoulder block 22. The shoulder block 22 is formed with a sipe-like ultra-thin shoulder lug groove 24 that terminates in the block from the circumferential narrow groove 14 toward the tread end 12E. The sipe-shaped extra-fine shoulder lug groove 24 is set to have a groove width that is closed immediately below the load during rolling, and the groove depth is the same as that of the main lug groove 16 at a maximum.

  Since the pneumatic tire 10 of the present embodiment is for a construction vehicle, it is preferable that the thickness (tread gauge) of the tread 12 on the tire equatorial plane CL be in the range of 60 mm to 200 mm.

As shown in FIG. 1 and FIG. 2 (C), a recess 26 that contacts the main lug groove 16 is formed on the tread surface of the shoulder block 22 of the present embodiment on the kicking end side.
The recess 26 is recessed from the tread 12 and the maximum depth is set within a range of 2 to 7% of the depth of the main lug groove 16 measured at the center position between the tire equatorial plane CL and the tread end 12E. It is preferable to do.
Moreover, it is preferable that the position where the depth of the recess 26 becomes the maximum depth is a position in contact with the main lug groove 16 and gradually decreases as the distance from the main lug groove 16 increases.

As shown in FIG. 1, the tire circumferential length OL of the recess 26 is formed within a range of 10 to 40% of the circumferential length BL of the shoulder block 22 at the center position between the tire equatorial plane CL and the tread end 12E. It is preferable to do.
Further, the recess 26 may be disposed on the outer side in the tire width direction than the center position between the tire equatorial plane CL and the tread end 12E and in the region on the tire equatorial plane CL side with respect to the end of the widest belt 28. preferable.

  In the present embodiment, the tread end 12E means that the pneumatic tire 10 is mounted on a standard rim prescribed in JATMA YEAR BOOK (2005 edition, Japan Automobile Tire Association Standard), and the applicable size / ply in JATMA YEAR BOOK. This is when the maximum load capacity is loaded with 100% internal pressure of the air pressure (maximum air pressure) corresponding to the maximum load capacity in the rating (bold load in the internal pressure-load capacity correspondence table). The tread width TW is a dimension measured in the tire width direction from one tread end to the other tread end. When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

(Function)
In the pneumatic tire 10, since the recess 26 is formed on the kicking end side of the tread surface of the shoulder block 22 formed on both sides in the tire width direction, the contact pressure of the portion where the recess 26 is formed is reduced. As shown in (D), deformation at the kicking end side of the shoulder block 22 during kicking (see FIG. 2B for this deformation) is suppressed, dragging to the road surface 102 is suppressed, and the kicking end It is possible to suppress uneven wear (so-called heel and toe wear) in which the side is greatly worn compared to the stepping end side. Further, since the width, length, depth, and position of the recess 26 are appropriately set, other performance is not deteriorated.

  When the unevenly worn portion is seen in the circumferential cross section, the wear depth decreases from the block end toward the block center, and accordingly, the depth of the recess 26 also increases from the block end toward the block center. It is preferable to reduce gradually.

  In addition, since the circumferential narrow groove 14 and the sipe-shaped ultra-fine center lug groove 20 are provided on the center side of the tread 12, heat dissipation is enhanced by these grooves, and heat generation due to a thick tread gauge is suppressed. Can do. If the position of the circumferential narrow groove 14 is on the inner side in the tire width direction from the position of 25% of the tread width TW with respect to the tire equatorial plane CL, the rigidity of the central region land portion 18 is reduced and wear resistance is increased. Decreases. On the other hand, if the position of the circumferential narrow groove 14 is on the outer side in the tire width direction with respect to the tire equatorial plane CL and more than 50% of the tread width TW, the heat generation near the tread center deteriorates and the durability decreases. There is a risk of doing.

  If the maximum depth of the recess 26 is less than 2% of the depth of the main lug groove 16 measured at the center position between the tire equatorial plane CL and the tread end 12E, the effect of suppressing uneven wear cannot be sufficiently obtained, and 7% Exceeding this causes a reduction in the contact area and deterioration of wear resistance.

  When the tire circumferential direction length OL of the recess 26 is less than 10% of the circumferential length BL of the shoulder block 22 at the center position between the tire equatorial plane CL and the tread end 12E, the effect of suppressing uneven wear cannot be sufficiently obtained. On the other hand, if the tire circumferential length OL of the recess 26 exceeds 40% of the circumferential length BL of the shoulder block 22 at the center position between the tire equatorial plane CL and the tread end 12E, the wear resistance deteriorates.

  If the thickness of the tread rubber forming the tread 12 is less than 60 mm, the durability of the tread 12 is insufficient in the pneumatic tire 10 of the present embodiment used for a construction vehicle. On the other hand, if the thickness of the tread rubber exceeds 200 mm, the heat generation durability deteriorates.

[Second Embodiment]
Next, 2nd Embodiment of the pneumatic tire of this invention is described based on drawing. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.

As shown in FIG. 3 (A), the pneumatic tire 10 of this embodiment is a modification of the pneumatic tire 10 of the first embodiment, and the circumferential narrow groove 14 has a zigzag shape, and a sipe shape. The ultra-fine center lug groove 20 is inclined.
Further, as shown in FIGS. 3A and 3B, recesses 26 are formed on both sides in the circumferential direction of the shoulder block 22 (the kicking side and the stepping side).

  In the pneumatic tire 10 of the present embodiment, since the recesses 26 are formed on both sides in the circumferential direction of the shoulder block 22, even when the pneumatic tire 10 is mounted in the reverse direction by rotation or the like, Since the recess 26 is always located on the kicking side, uneven wear can be suppressed regardless of the mounting direction. Further, when uneven wear occurs on the stepping end side, uneven wear on the stepping end side can be suppressed.

(Test example)
In order to confirm the effect of the present invention, one type of conventional tire and two types of tires according to the embodiments of the present invention were prepared, the block center slip amount, the kick end slip amount, and the heel and The toe property (H & T resistance) was examined.
In all cases, the tire size is 46 / 90R57, the rim size is 29 inches wide, the flange height is 6 inches, the internal pressure is 700 kPa, and the load is 60 ton. The center position.

The slip amount was measured by running a tire having measurement points on the tread surface on a transparent road surface and photographing the locus of the measurement points with a video camera. The evaluation is an index display in which the slip amount of the conventional example is 100, and the smaller the index value, the smaller the slip amount with respect to the road surface.
The heel and toe resistance is evaluated by the ratio of the slip amount at the kicking end and the slip amount at the center in the block circumferential direction. The larger the value, the better the heel-and-toe resistance (hardness of heel-and-toe wear).
Table 1 below shows the specifications of each tire and the test results.

It is a top view of the tread of the pneumatic tire concerning a 1st embodiment. (A) is a side view of a conventional block, (B) is a side view when kicking out the conventional block, and (C) is a cross-sectional view of the shoulder block of the first embodiment (FIG. 1 (A) 2C-2C sectional view)), and (D) is a side view when the shoulder block of the first embodiment is kicked out. (A) is a top view of the tread of the pneumatic tire which concerns on 2nd Embodiment, (B) is sectional drawing of a shoulder block.

Explanation of symbols

10 Pneumatic tire 22 Shoulder block 26 Recess

Claims (8)

Provided with a plurality of lug grooves arranged at intervals in the tire circumferential direction on both sides in the tire width direction of the tread,
A depression that is lower than the tread tread that contacts the road surface and shallower than the lug groove is disposed adjacent to the lug groove on the tread surface of the land located between the lug grooves adjacent in the circumferential direction. A pneumatic tire characterized by that. The pneumatic tire according to claim 1, wherein a rotation direction is specified, and the recess is formed only on a kicking end side of the land portion. 2. The pneumatic tire according to claim 1, wherein the recess is formed on a kicking end side and a stepping end side of the land portion. The maximum depth of the dent is set within a range of 2 to 7% of the groove depth of the lug groove measured at the center position between the tire equatorial plane and the tread edge. The pneumatic tire according to any one of claims 3 to 4. The pneumatic tire according to claim 4, wherein a position at which the maximum depth of the dent is a position in contact with the lug groove, and the depth of the dent changes in a tire circumferential direction. The tire has a tire circumferential length set in a range of 10 to 40% of a circumferential length of the land portion at a central position between a tire equatorial plane and a tread end. The pneumatic tire according to any one of claims 1 to 5. The dent is disposed on the tire equatorial plane side more than the end portion of the widest belt on the outer side in the tire width direction than the center position between the tire equatorial plane and the tread end. The pneumatic tire according to any one of claims 1 to 6. The pneumatic tire according to any one of claims 1 to 7, wherein a thickness of the tread rubber constituting the tread is in a range of 60 to 200 mm.

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