JP2010155502A - Tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire making compatible insurance of traction performance and suppression of uneven wear of a second land part. <P>SOLUTION: A center main groove 20 extending in a zig-zag form in a tire circumferential direction U and shoulder main grooves 22L, 22R linearly extending in the tire circumferential direction U are formed on a tread part 78. As a result, the second land parts 30L, 30R positioned between the center main groove 20 and the shoulder main grooves 22L, 22R respectively are formed. On the second land part 30L, a land part edge 30EL at an outer side in a width direction is linear in plan view, and a land part edge 30FL at an inner side in a width direction is a zig-zag form in plan view. It is similar regarding the second land part 30R. Further, on the second land parts 30L, 30R, second lateral grooves 40L, 40R are formed respectively, and on the shoulder land parts 80L, 80R adjacent to an outer side in a width direction of the shoulder main grooves 22L, 22R, shoulder lateral grooves 70L, 70R are formed respectively. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tire in which at least three main grooves extending in the circumferential direction are formed in a tread portion. More specifically, the present invention relates to a tire suitable particularly when a heavy load is applied.

In a tire in which main grooves are formed along the tire circumferential direction, it has been proposed to form the main grooves in a zigzag shape in the circumferential direction in order to ensure traction performance (for example, Patent Document 1). Note that securing the traction performance in such a shape is particularly effective for heavy-duty tires.
Japanese Patent Laid-Open No. 2004-210235

  However, if the main groove located on the outer side in the tire width direction is formed in this zigzag shape, uneven wear nuclei are generated due to this shape, and the tire in the second land portion is particularly caused by the difference in land portion rigidity in the tire circumferential direction. There was a problem that uneven wear of the outer portion in the width direction was promoted. Patent Document 1 proposes to suppress such uneven wear, but further improvement is required.

  In view of the above facts, an object of the present invention is to provide a tire that achieves both traction performance and suppression of uneven wear in the second land portion.

  In the invention according to claim 1, in the second land portion adjacent to the inner side in the width direction of the outermost main groove in the width direction, at least three main grooves extending in the circumferential direction are formed in the tread portion. The land edge on the outer side in the width direction is linear in plan view, the land edge on the inner side in the width direction is zigzag in plan view, and is adjacent to the second land portion and the width direction outer side of the outermost main groove in the width direction A lateral groove is formed on the shoulder land

In the invention according to claim 1, since the land portion edge on the outer side in the width direction of the second land portion is linear in plan view, the land portion rigidity in the circumferential direction is formed in the land portion on the outer side in the width direction of the second land portion. The difference is suppressed. Accordingly, uneven wear is suppressed in the land portion on the outer side in the width direction of the second land portion.
In addition, since the land portion edge on the inner side in the width direction of the second land portion has a zigzag shape in plan view, the traction performance can be obtained at the land portion portion on the inner side in the width direction of the second land portion.

  And since the horizontal groove is formed in the second land part and the shoulder land part, traction performance can be obtained by the edge of the horizontal groove. Therefore, the traction performance impaired by the land portion edge in the width direction outer side of the second land portion being linear in a plan view can be sufficiently compensated by the lateral groove, and the traction performance of the tire is ensured.

  In general, tires mounted on the steering shaft mainly require uneven wear resistance, and tires mounted on the drive shaft mainly require traction performance. The performance of both is in a trade-off relationship. That is, when emphasis is placed on uneven wear resistance performance on the steer shaft, straight grooves that are generally found in tires exclusively for steer bearings are formed. On the other hand, in the pattern mainly composed of the straight groove, the traction performance is impaired when used on the drive shaft. In the invention according to claim 1, since it is possible to achieve both the traction performance and the suppression of the uneven wear of the second land portion, the tire that can be applied to both the steer shaft and the drive shaft, that is, the distinction of the mounting shaft. It is possible to make it an all-position tire that can be used without any problems.

  According to a second aspect of the present invention, a center main groove extending in a zigzag shape at the tire center is formed as the main groove.

The phrase “zigzag extending in the circumferential direction” means that the groove portions that are inclined with respect to the circumferential direction extend in the tire circumferential direction while turning back so that the inclination directions are alternate.
In the invention according to claim 2, the center main groove has a zigzag shape in the tire center portion that greatly affects the traction performance and is less influenced by uneven wear. Therefore, it is possible to efficiently ensure the traction performance while efficiently suppressing the influence of uneven wear.

  According to a third aspect of the present invention, the widthwise outer end of the shoulder lateral groove formed in the shoulder land portion of the lateral groove is closed in the shoulder land portion.

  When the effect of suppressing the uneven wear of the second land portion is obtained by the invention of claim 1, the use limit (rejection life) of the tire due to the wear is determined by the uneven wear (H & T wear) of the shoulder land portion. Therefore, when the widthwise outer end of the shoulder lateral groove does not reach the widthwise outer end of the shoulder land portion and is closed in the shoulder land portion as in the invention described in claim 3, uneven wear of the shoulder land portion is caused. Is suppressed, and the service life (travelable distance) of the tire can be extended.

According to a fourth aspect of the present invention, the second lateral groove formed in the second land portion of the lateral groove and the shoulder lateral groove are formed in a row.
Thereby, it is easy to improve the traction performance.

  According to a fifth aspect of the present invention, the depth of the second lateral groove and the shoulder lateral groove is in the range of 1 to 3 mm, and the width of the second lateral groove and the shoulder lateral groove is in the range of 2 to 5 mm.

If the depth of the second lateral groove and the shoulder lateral groove is less than 1 mm, it is difficult to obtain the effect of improving the traction by the lateral groove. And if the depth of a second horizontal groove and a shoulder horizontal groove is deeper than 3 mm, a shoulder land part will become easy to carry out partial wear.
Moreover, when the width of the second lateral groove and the shoulder lateral groove is narrower than 2 mm, it is difficult to obtain the effect of improving the traction property by the lateral groove. And if the width of the second lateral groove and the shoulder lateral groove is wider than 5 mm, the shoulder land portion is likely to be unevenly worn.
In the fifth aspect of the present invention, by ensuring the depth and width of the lateral grooves in this way, it is easy to achieve both traction performance and uneven wear prevention.

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as the tire which made the balance of ensuring of traction performance and suppression of the partial wear of a 2nd land part compatible.

  Hereinafter, pneumatic tires for buses and trucks will be cited as embodiments, and embodiments of the present invention will be described. In the second and subsequent embodiments, the same components as those already described are denoted by the same reference numerals, and description thereof is omitted.

[First Embodiment]
First, the first embodiment will be described. As shown in FIG. 1, a pneumatic tire 10 according to an embodiment of the present invention is a truck / bus tire and includes a carcass 12. The carcass 12 has a folded portion 12E in which both end portions are folded at the bead core 11C of the bead portion 11 respectively.

  A belt layer 14 is embedded outside the crown portion 12C of the carcass 12 in the tire radial direction. On the outer side of the belt layer 14 in the tire radial direction, a tread portion 18 (see also FIG. 2) provided with a groove is formed.

  As shown in FIG. 2, the tread portion 18 has a center main groove 20 that extends in a zigzag shape in the tire circumferential direction U on the tire center CL, and the tire circumferential direction located on both sides of the center main groove 20 in the tire width direction. Shoulder main grooves 22 </ b> L and 22 </ b> R that extend linearly in U are formed. By these three main grooves, a total of four land portion rows of the second land portion rows 30L and 30R and the shoulder land portion rows 50L and 50R are formed in the tread portion 18. In the present embodiment, each of the center main groove 20 and the shoulder main grooves 22L and 22R has a depth of 13 to 20 mm and a width of 12 to 16 mm.

  Further, the center main groove 20 has a zigzag shape, and the shoulder main grooves 22L and 22R have a linear shape. Therefore, in the second land portion row 30L located between the shoulder main groove 22L and the center main groove 20, the land portion edge 30EL on the outer side in the width direction is linear in plan view, and the land portion edge 30FL on the inner side in the width direction is seen in plan view. Zigzag shape. Similarly, in the second land portion row 30R, the land portion edge 30ER on the outer side in the width direction has a linear shape in plan view, and the land portion edge 30FR on the inner side in the width direction has a zigzag shape in plan view.

  In the present embodiment, the outer ends in the width direction of the shoulder land portion rows 50L and 50R are the tread ends T. Here, the tread end T means that a pneumatic tire is mounted on a standard rim prescribed in JATMA YEAR BOOK (2008 edition, Japan Automobile Tire Association Standard), and is the maximum applicable size / ply rating in JATMA YEAR BOOK. Fills 100% of the air pressure (maximum air pressure) corresponding to the load capacity (internal pressure-load capacity correspondence table) as the internal pressure, and indicates the outermost ground contact portion in the tire width direction when the maximum load capacity is loaded. In addition, when TRA standard and ETRTO standard are applied in a use place or a manufacturing place, it follows each standard.

  The second land portion row 30L includes a short inner lug groove 34L that extends from the center main groove-side bent convex portion 32L formed by the center main groove 20 and ends in the land portion row, and extends from the shoulder main groove 22L. A short outer lug groove 38 </ b> L that exits and terminates in the middle of the land portion row is arranged along the tire circumferential direction U. Furthermore, in the second land portion row 30L, a second lateral groove 40L that connects the inner lug groove 34L and the outer lug groove 38L is arranged.

  Similarly, the second land portion row 30R includes a short inner lug groove 34R extending from the center main groove-side bent convex portion 32R formed by the center main groove 20 and terminating in the middle of the land portion row, and a shoulder main groove. Short outer lug grooves 38 </ b> R extending from 22 </ b> R and terminating in the middle of the land portion row are arranged along the tire circumferential direction U. Similarly to the second land portion row 30L, the second land portion row 30R is arranged with a second lateral groove 40R connecting the inner lug groove 34R and the outer lug groove 38R.

  In the present embodiment, each of the second horizontal grooves 40L and 40R has a depth of 1 to 3 mm and a width of 2 to 5 mm. In FIG. 2, the second horizontal grooves 40L and 40R are drawn as curved grooves, but the second horizontal grooves 40L and 40R may be linear grooves.

  In the shoulder land portion row 50L, a short inner lug groove 54L extending from the shoulder main groove 22L and terminating in the middle of the land portion row is formed. The shoulder land portion row 50L is formed with a shoulder lateral groove 60L that extends from the inner lug groove 54L and opens at the outer end in the width direction of the shoulder land portion row 50L. The shoulder lateral groove 60L is disposed at a position continuous with the second lateral groove 40L.

In the shoulder land portion row 50R, a short inner lug groove 54R extending from the shoulder main groove 22R and terminating in the land portion row is formed. The shoulder land portion row 50R is formed with a shoulder lateral groove 60R extending from the inner lug groove 54R and opening at the outer end in the width direction of the shoulder land portion row 50R. The shoulder lateral groove 60R is also arranged at a position continuous with the second lateral groove 40R.
The depth and width of the shoulder lateral groove 60L are the same as those of the second lateral groove 40L, and the depth and width of the shoulder lateral groove 60R are also the same as those of the second lateral groove 40R.

  As described above, in the present embodiment, since the land portion edge 30EL on the outer side in the width direction of the second land portion row 30L is linear in plan view, the land portion 30LE on the outer side in the width direction of the second land portion row 30L. Then, the difference in the rigidity of the land portion in the circumferential direction is suppressed. Therefore, uneven wear in the land portion 30LE on the outer side in the width direction of the second land portion row 30L is suppressed. Similarly, in the second land portion row 30R, uneven wear in the land portion 30RE on the outer side in the width direction is suppressed.

  Further, since the land portion edge 30FL on the inner side in the width direction of the second land portion row 30L has a zigzag shape in plan view, the traction performance can be obtained by the land portion 30LF on the inner side in the width direction of the second land portion row 30L. The traction performance can be obtained by the edges of the second lateral groove 40L and the shoulder lateral groove 60L. Accordingly, the traction performance impaired by the land portion edge 30EL on the outer side in the width direction of the second land portion row 30L being linear in plan view can be sufficiently supplemented by the second lateral groove 40L and the shoulder lateral groove 60L. The traction performance in the tread portion in the left half of the paper surface of the tire center CL is sufficiently ensured. Similarly, the traction performance is sufficiently ensured for the tread portion in the right half of the paper surface of the tire center CL.

  Therefore, it is possible to provide the pneumatic tire 10 in which the traction performance is ensured and the uneven wear of the second land portion is suppressed.

  The depth of the second lateral grooves 40L and 40R and the shoulder lateral grooves 60L and 60R is in the range of 1 to 3 mm, and the width of the second lateral grooves 40L and 40R and the shoulder lateral grooves 60L and 60R is in the range of 2 to 5 mm. Therefore, it is possible to provide the pneumatic tire 10 that facilitates ensuring both traction performance and preventing uneven wear.

  In FIG. 2, the second lateral groove 40L, the shoulder lateral groove 60L, the second lateral groove 40R, and the shoulder lateral groove 60R are illustrated as being continuous, but these lateral grooves may be discontinuous.

[Second Embodiment]
Next, a second embodiment will be described. As shown in FIG. 3, the present embodiment is different from the first embodiment in that shoulder lateral grooves 70L and 70R are formed in the tread portion 78 instead of the shoulder lateral grooves 60L and 60R. The width direction outer end 71L of the shoulder lateral groove 70L is closed in the shoulder land portion 80L, and the width direction outer end 71R of the shoulder lateral groove 70R is also closed in the shoulder land portion 80R. The lateral groove shape from the width direction outer end 71L to the width direction outer end 71R is S-shaped. The depth and width ranges of the shoulder lateral grooves 70L and 70R are the same as those in the first embodiment.
According to the present embodiment, the uneven wear of the shoulder land portions 80L and 80R is suppressed as compared with the first embodiment, and the service life (travelable distance) of the tire can be extended.

  In addition, you may form the sipe along the said S shape in 2nd land part row | line | column 30L, 30R. Thereby, the traction performance can be further improved. Further, the depth of the sipe is preferably not more than the depth of the center main groove 20 and the shoulder main grooves 22L and 22R and in the range of 2 to 20 mm, and the width of the sipe is in the range of 30 to 70 mm. preferable.

<Test example>
In order to confirm the effect of the present invention, the inventor has an example of the pneumatic tire 10 of the first embodiment (hereinafter referred to as a tire of Example 1) and an example of the pneumatic tire of the second embodiment (hereinafter, implementation). Example 2) and an example of a conventional pneumatic tire (hereinafter referred to as a conventional tire) were prepared, and performance tests were performed by running an actual vehicle to evaluate the performance.

  Here, in the conventional tire, as shown in FIG. 4, a center main groove 90 extending in a zigzag shape in the tire circumferential direction U and shoulder main grooves 92L, 92R extending in a zigzag shape in the tire circumferential direction U are tread portions. 98. A plurality of lateral grooves 100 that are connected to the center main groove 90 and extend from the shoulder main groove 92L to the shoulder main groove 92R are formed.

  In this test example, all tires are bus / truck tires, and the tire sizes are all the same.

In this test example, three testers were selected as testers to perform the test.
As a vehicle, 2-D-D (a vehicle in which one tire is mounted on the left and one on the front and rear. That is, there are two drive shafts, two on each side by mounting tires on both sides of each drive shaft. 24 vehicles (equipped with tires) were prepared, and the test was performed using 8 units per tester.
Further, the number of tires per one tester used in the test was 12 tires of Example 1, 12 tires of Example 2, and 24 conventional tires.

  In this test example, all tires were installed in normal rims and then subjected to normal running with normal internal pressure. Here, “regular rim” means, for example, a standard rim in the applicable size specified in the 2008 edition YEAR BOOK issued by JATMA, and “normal load” and “regular internal pressure” are similarly issued by JATMA. The maximum load in the applicable size and ply rating defined in the 2007 YEAR BOOK and the air pressure with respect to the maximum load. When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

And about each tire, the volume which carried out partial wear (H & T wear) was measured. Then, the uneven wear resistance performance of the conventional tire was set as the evaluation index 100, and the evaluation index for relative evaluation was calculated for the other tires. The evaluation results of uneven wear resistance performance are shown in Table 1.

  The evaluation results in Table 1 indicate that the larger the evaluation index, the higher the performance, that is, the better the uneven wear resistance performance. As can be seen from Table 1, in the tire of Example 1, the uneven wear resistance performance of the second land portion could be greatly improved without significantly degrading the uneven wear resistance performance of the shoulder land portion. In the tire of Example 2, the uneven wear resistance of the second land portion could be greatly improved without reducing the uneven wear resistance performance of the shoulder land portion at all.

  In addition, the traction performance of each tire was evaluated based on the feeling of the test driver. As a result, the traction performance was the same for all tires, and the tire of Example 1 and the tire of Example 2 were evaluated as having the same traction performance as the conventional tire.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. It goes without saying that the scope of rights of the present invention is not limited to these embodiments.

It is radial direction sectional drawing of the pneumatic tire which concerns on 1st Embodiment. It is a top view which shows the tread pattern of the pneumatic tire which concerns on 1st Embodiment. It is a top view which shows the tread pattern of the pneumatic tire which concerns on 2nd Embodiment. It is a top view which shows the tread pattern of the conventional pneumatic tire used for the test example.

Explanation of symbols

10 Pneumatic tire (tire)
18 tread 20 center main groove 22L, R shoulder main groove 30L, R second land part row (second land part)
50L, R Shoulder land part row (shoulder land part)
30EL, ER, FL, FR Land portion edge 40L, R second lateral groove 60L, R shoulder lateral groove 70L, R shoulder lateral groove 78 tread portion 71L, R width direction outer end 80L, R shoulder land portion 90 center main groove 92L, R shoulder main Groove 100 lateral groove (second lateral groove)
CL Tire Center U Tire circumferential direction

Claims (5)

At least three main grooves extending in the circumferential direction are formed in the tread portion,
In the second land portion adjacent to the inner side in the width direction of the outermost main groove in the width direction, the land edge on the outer side in the width direction is linear in plan view, and the land edge on the inner side in the width direction is zigzag in plan view. And
And the tire by which a lateral groove is formed in the said second land part and the shoulder land part adjacent to the width direction outer side of the said width direction outermost main groove.   The tire according to claim 1, wherein a center main groove extending in a zigzag shape in a circumferential direction at a tire center is formed as the main groove.   The tire according to claim 1 or 2, wherein an outer end in a width direction of a shoulder lateral groove formed in the shoulder land portion of the lateral groove is closed in the shoulder land portion.   The tire according to claim 3, wherein a second lateral groove formed in the second land portion of the lateral grooves and the shoulder lateral groove are formed in a row. The depth of the second lateral groove and the shoulder lateral groove is in the range of 1 to 3 mm,
The tire according to claim 4, wherein a width of the second lateral groove and the shoulder lateral groove is in a range of 2 to 5 mm.

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