JP5922745B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire for a snowy road in which a plurality of sipes are formed on a land block.

  Conventionally, in order to improve acceleration performance when starting a vehicle on a snowy road, braking performance at the time of braking, and steering stability, a technique of forming a groove called a thin sipe on a tread surface of a tire has been widely used (for example , See Patent Document 1).

JP 2006-192929 A

  However, in the pneumatic tire described in Patent Document 1, although the performance on snow improves when the sipe density in a specific land block is set large, the rigidity of the land block is lower than that of other land blocks. For this reason, there is a problem that the driving stability when traveling on a dry road or a wet road surface is lowered.

  The objective of this invention is providing the pneumatic tire which can suppress the rigidity fall of the land block even if it provides many sipes in a specific land block.

  The first feature of the present invention is that the tire width intersects the circumferential groove (center side circumferential groove 2, mounting outer circumferential groove 3, mounting inner circumferential groove 4) extending in the tire circumferential direction and the circumferential groove. A plurality of land blocks (first central land row 5, second central land row 7, shoulder land portion row) on the tread surface by lateral grooves (lateral grooves 6, lug grooves 8, 11, 12) extending in the direction. 9 and 10), and a pneumatic tire (pneumatic tire 1) in which sipes (sipes 21 to 24) are formed on the surface of each land block, and a predetermined one of the plurality of land blocks The land block (land block 31) is set to be higher than the sipe density of other land blocks and smaller than the negative rate of the other land blocks, and the predetermined land block is , Offset outside the tire center It is summarized as disposed on bets position.

  In this way, the predetermined land block is higher than the sipe density of the other land block and smaller than the negative rate of the other land block, so the block rigidity of the predetermined land block is kept high. The sipe density can be increased. Thereby, it is possible to achieve both the performance on snow and the operability when traveling on a normal dry road or a wet road surface.

  In other features, the lateral groove (lateral groove 6) that defines the predetermined land block (land block 31) has a narrow narrow portion (intermediate portion 6a) with a narrow width ( The gist is that the narrow portion 6b) and a wide portion (wide portion 6c) wider than the narrow portion are included.

  Another feature is that the predetermined land block is disposed in a shoulder land portion row (shoulder land portion row 9, 10).

  According to the pneumatic tire according to the present invention, both performance on snow and operability when traveling on a normal dry road surface or a wet road surface can be achieved.

1 is a tread pattern of a pneumatic tire according to an embodiment of the present invention. It is an enlarged view of the principal part of FIG.

  Hereinafter, details of a pneumatic tire according to an embodiment of the present invention will be described with reference to the drawings. However, it should be noted that the drawings are schematic, and the thicknesses and ratios of the material layers are different from actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

  FIG. 1 is a tread pattern of a pneumatic tire 1 according to an embodiment of the present invention. FIG. 2 is an enlarged view of a main part of FIG.

  As shown in FIG. 1, a plurality of circumferential grooves extending along the tire circumferential direction (hereinafter referred to as “circumferential direction”) are provided. A center-side circumferential groove 2 is formed slightly outside the tire equator line CL, and a mounting-outer circumferential groove 3 is disposed outside the center-side circumferential groove 2. A mounting inner circumferential groove 4 is disposed on the inner side of the center side circumferential groove 2.

  Further, a first central land row 5 is formed between the central circumferential groove 2 and the mounting outer circumferential groove 3, and the first central land row 5 has a tire width direction ( Hereinafter, the lateral groove 6 extends along the “width direction”. A second central land portion row 7 is formed between the central side circumferential groove 2 and the mounting inner circumferential groove 4. The second central land portion row 7 has a width direction. A lug groove 8 extends along.

  Also, shoulder land portion rows 9 and 10 are provided on the outer side of the mounting outer circumferential groove 3 and on the inner side of the mounting inner circumferential groove, and the shoulder land portion rows 9 and 10 have Lug grooves 11 and 12 extending in the width direction are formed. A circumferential narrow groove 12 extending in the circumferential direction is formed between the central circumferential groove 2 and the mounting inner circumferential groove 4. The first central land portion row 5, the second central land portion row 7, and the shoulder land portion rows 9, 10 each have a plurality of sipes (narrow grooves) 21, 22, 23, 24 along the width direction. Is formed.

  In addition, as shown in FIG. 2, the first central land row 5 includes a land block defined by a central side circumferential groove 2, a mounting outer circumferential groove 3, and a lateral groove 6 in a substantially rectangular shape in plan view. A plurality of elements 31 are arranged along the circumferential direction. The lateral groove 6 extends while inclining toward the tire rotation direction as it goes outward in the width direction (outside of mounting). In addition, a narrow portion 6b having a narrow width dimension with an intermediate portion 6a in the width direction as a boundary, and a wide portion 6c having a wider width dimension than the narrow portion 6b. Specifically, in FIG. 2, the portion outside the attachment from the intermediate portion 6 a is the narrow portion 6 b, and the portion inside the attachment from the intermediate portion 6 c is set as the wide portion 6 c. In the land portion block 31, a plurality (six in this embodiment) of sipes 21 extending substantially in parallel with the lateral grooves 6 are arranged at predetermined intervals in the circumferential direction.

  And among the plurality of land blocks, the predetermined land block 31 constituting the first central land row 5 is more than the sipe density of other land blocks constituting the second central land row 7. It is set higher than the negative rate of other land blocks. Here, the sipe density is the ratio of the area occupied by the sipe to the pattern area of the predetermined part. For the predetermined land block 31 of FIG. 2, the ratio of the area occupied by the sipe 21 is higher than that of other land blocks. It is set large. As shown in FIG. 1, the negative rate of the first central land row 5 is set smaller than the negative rate of other land blocks, for example, the second central land row 7. Here, the negative rate is the ratio of the entire groove area to the pattern area of the predetermined portion on the tread surface. In particular, in the second central land portion row 7, since the lug grooves 8 are wide and the circumferential narrow grooves 12 are also formed, the ratio of the entire groove area is large.

  Moreover, as shown in FIG. 1, the predetermined land block 31 is arranged at a position offset from the tire equator line CL to the mounting outer side.

  Below, the effect by embodiment of this invention is demonstrated.

<Operation effect>
(1) The pneumatic tire 1 according to the present embodiment includes a central circumferential groove 2, a mounting outer circumferential groove 3, a mounting inner circumferential groove 4, and circumferential grooves 2, 3, 4 extending in the tire circumferential direction. The first central land row 5 and the second central land row 7 which are a plurality of land blocks on the tread surface by the lateral grooves 6 and the lug grooves 8, 11, 12 extending in the tire width direction intersecting with The pneumatic tire 1 has shoulder land rows 9 and 10 and sipe 21 to 24 formed on the surface of each land block, and a predetermined land block 31 of the plurality of land blocks is It is set to be higher than the sipe density of other land blocks and smaller than the negative rate of other land blocks.

  Thus, since the predetermined land block 31 is higher than the sipe density of other land blocks and smaller than the negative rate of other land blocks, the block rigidity of the predetermined land block 31 is increased. The sipe density can be increased while maintaining. As a result, it is possible to achieve both performance on snow and operability when traveling on a normal dry road surface or a wet road surface.

(2) The lateral groove 6 that defines the predetermined land block 31 is composed of a narrow narrow portion 6b and a wide wide portion 6c with the intermediate portion 6a in the tire width direction as a boundary.

  Thus, since the intermediate part 6a vicinity of the horizontal groove 6 can be bent, the block rigidity of the land part block 31 can be improved.

(3) The predetermined land portion block 31 is disposed at a position offset from the tire equator line CL toward the mounting outer side.

  Therefore, the effect of improving the straight running stability on snow can be obtained.

  It should not be understood that the description and the drawings, which form part of the disclosure of the above-described embodiments, limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, although the predetermined land block 31 is arranged in the first central land row 5 close to the tire equator line CL, it may be arranged in the shoulder land rows 9 and 10.

  Next, the present invention will be described more specifically through examples.

  The test tire according to the conventional example has a size of 195 / 65R15, and was mounted on a rim wheel having a rim size of 6 J × 15 inches with an internal pressure of 220 kPa. In the test tire according to this conventional example, the sipe density was set to substantially the same density throughout the tread pattern.

  Further, the test tire according to the example of the present invention was attached to a rim wheel having a size of 205 / 55R16 and a rim size of 6.5 J × 16 inches with an internal pressure of 220 kPa. In the test tire according to this example of the present invention, the sipe density in the predetermined land block was set larger than that in the other land blocks as in the above-described embodiment of the present invention. These test tires were attached to a vehicle (FF vehicle) and traveled on a snowy road and a dry road. The results are shown in Table 1.

  As shown in Table 1, it was found that the example of the present invention was superior to the conventional example in all of the traction performance on snow, the operability of snow road traveling, and the operability of dry road traveling.

1 Pneumatic tire 2 Center side circumferential groove (circumferential groove)
3 Outer circumferential groove (circumferential groove)
4 Wearing inner circumferential groove (circumferential groove)
6 lateral groove 6a middle part 6b narrow part 6c wide part 8, 11, 12 lug groove (lateral groove)
21-24 Sipe 31 Land Block

Claims (3)

The plurality of circumferential grooves extending in the tire circumferential direction and the lateral grooves extending in the tire width direction intersecting the circumferential grooves form a plurality of land blocks on the tread surface, and sipe is formed on the surface of each land block. A pneumatic tire formed of
The circumferential groove includes a central circumferential groove positioned on the outer side of the tire equator line, a mounting outer circumferential groove positioned on the outer side of the central circumferential groove, and the central circumferential groove. A mounting inner circumferential groove located on the inner side is formed,
A first central land portion row formed between the central circumferential groove and the mounting outer circumferential groove; and a first central land portion row formed between the central circumferential groove and the mounting inner circumferential groove. Two central land rows,
In the second central land portion row, a circumferential narrow groove that is narrower than the circumferential groove and extends in the tire circumferential direction is formed,
Among the plurality of land blocks, a predetermined land block included in the first central land row is higher than a sipe density of another land block and has a negative rate of the other land blocks. Is set smaller than
The pneumatic tire according to claim 1, wherein the predetermined land block is disposed at a position offset from the tire center toward the mounting outer side.   The lateral groove defining the predetermined land block is composed of a narrow portion having a narrow width with an intermediate portion in the tire width direction as a boundary, and a wide portion having a width wider than the narrow portion. The pneumatic tire according to claim 1. 3. The pneumatic tire according to claim 1, wherein the predetermined land portion block is disposed in a shoulder land portion row formed outside the mounting outer circumferential groove .

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