JP2010120534A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving the high-speed performance, especially, durability in high-speed traveling, securing driving stability. <P>SOLUTION: This pneumatic tire includes a plurality of blocks 7A, 7B and 7C formed by a plurality of circumferential grooves 3 extending in the tire circumferential direction and a plurality of cross directional grooves 5 extending in the tread cross direction in a tread 1. Each of the blocks 7A, 7B and 7C has a recess recessed inside in the tire radial direction in the tread, and the recessed amount inside in the tire radial direction in each recess is set corresponding to the pitch length of each of the blocks 7A, 7B and 7C as the length in the tire circumferential direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having a plurality of blocks formed by a plurality of circumferential grooves and a plurality of width grooves.

Conventionally, various proposals have been made on pneumatic tires that are superior in handling stability by improving grip performance (performance for grasping the ground). For example, a pneumatic tire is disclosed in which, on a tread surface, a plurality of blocks formed by a plurality of circumferential grooves and a plurality of width grooves are provided with recesses that are recessed inward in the tire radial direction (for example, , See Patent Literature 1 to Patent Literature 3).
Japanese Utility Model Publication No. 48-87704 (pages 3 to 4 and FIG. 1) Japanese Utility Model Publication No. 60-110110 (1st page-2nd page, Fig. 1) JP 57-167803 (first page, FIG. 1)

  Incidentally, in recent years, pneumatic tires are usually provided with pitch variations, and even in the same basic block, the length is often different in the tire circumferential direction.

  However, in the conventional pneumatic tire, all of the blocks having different lengths are provided with a certain recess, and the contact pressure of the long block having a long pitch length, which is the length in the tire circumferential direction, and the bitch length However, the current situation is that there is a concern that the difference with the ground pressure of a short short block becomes large and adversely affects the steering stability (handling performance).

  Further, in each of the conventional pneumatic tires described above, since the constant depressions are provided in all the blocks, in particular, the accumulated heat accumulated in the long blocks cannot be reduced, and at the center bottom of the long blocks. It is difficult to dissipate the accumulated heat that is accumulated, resulting in a problem that high-speed performance, particularly high-speed durability, is reduced.

  Therefore, the present invention has been made in view of such a problem, and an object thereof is to provide a pneumatic tire capable of improving high-speed performance, particularly high-speed durability, while ensuring steering stability. And

  In order to solve the above situation, the present invention has the following features. First, the invention according to the first feature of the present invention is a tread surface including a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of widthwise grooves extending in the tread width direction. A plurality of blocks having dents that dent inward in the tire radial direction on the tread surface, and the amount of dents indented inward in the tire radial direction in each dent The gist is that it is set corresponding to the pitch length which is the length in the circumferential direction.

  According to this feature, the amount of heat accumulated in the block can be reduced regardless of the size of the block by setting the dent amount corresponding to the pitch length, and at the center bottom of the block. Since accumulated heat accumulated can be dissipated, high-speed performance, particularly high-speed durability, can be improved while ensuring steering stability.

  The gist of the invention relating to the other feature is that the dent amount of the long block having the longest pitch length among the plurality of blocks is set deeper than the dent amount of the short block having the shortest pitch length among the plurality of blocks. To do.

  According to such a feature, the depth of the long block is set deeper than the length of the short block, so that the cage thickness is reduced in the central portion of the long block (that is, the height of the central portion of the block is reduced). ) In addition, since the area of the long block that comes into contact with the outside air can be increased, it becomes easier to dissipate the accumulated heat at the center bottom of the long block, where accumulated heat is most likely to be accumulated, and promote the heat radiation of the entire long block It becomes possible.

  The gist of the invention according to another feature is that the recess is gradually set deeper toward the center bottom of the tread surface.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which can improve high-speed performance, especially high-speed durability can be provided, ensuring steering stability.

  Next, an example of a pneumatic tire according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones. Accordingly, specific dimensions and the like 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.

(Composition of pneumatic tire)
FIG. 1 is a development view showing a tread pattern of a pneumatic tire according to the present embodiment, and FIG. 2 is a perspective view / sectional view showing a long block formed in the pneumatic tire according to the present embodiment. FIG. 3 is a perspective view / sectional view showing a middle block formed in the pneumatic tire according to the present embodiment, and FIG. 4 is a short block formed in the pneumatic tire according to the present embodiment. FIG. 5 is a front comparison view showing a pneumatic tire long block, a medium block, and a short block according to the present embodiment.

  The pneumatic tire according to the present embodiment is a general radial tire including a bead portion, a carcass layer, a belt layer, and a tread portion (not shown). Moreover, the pneumatic tire according to the present embodiment is mounted on a passenger car.

  As shown in FIG. 1, the tread surface 1 of a pneumatic tire is formed by a plurality of circumferential grooves 3 extending in the tire circumferential direction and a plurality of width grooves 5 extending in the tread width direction. A plurality of blocks 7 are provided.

  The plurality of blocks 7 includes a long block 7A having the longest pitch length which is the length in the tire circumferential direction among the plurality of blocks 7, and a pitch length shorter than the long block 7A and shorter than a short block 7C described later. The medium block 7B having a long length and the short block 7C having the shortest pitch length among the plurality of blocks 7 are configured.

  The plurality of blocks 7 have recesses 9 that are recessed inward in the tire radial direction on the tread surface.

  Specifically, as shown in FIG. 2, the long block 7 </ b> A has a long recess 9 </ b> A that is recessed toward the inner side in the tire radial direction on the tread surface 1. Further, as shown in FIG. 3, the middle block 7 </ b> B has a middle recess 9 </ b> B that is recessed toward the inner side in the tire radial direction on the tread surface 1. Further, as shown in FIG. 4, the short block 7 </ b> C has a short recess 9 </ b> C that is recessed toward the inner side in the tire radial direction on the tread surface 1.

  The dent amount (ha, hb, hc) indented inward in the tire radial direction in each dent 9 (long dent 9A, middle dent 9B, short dent 9C) is the length of the tire in the circumferential direction. It is set corresponding to (A, B, C).

  Specifically, as shown in FIG. 5, the recess amount (ha) of the long block 7A is set deeper than the recess amount (hb) of the middle block 7B and the recess amount (hc) of the short block 7C (ha). > Hb> hc). That is, the dent amount (hb) of the middle block 7B is set shallower than the dent amount (ha) of the long block 7A, and is set deeper than the dent amount (hc) of the short block 7C. Further, the recess amount (hc) of the short block 7C is set shallower than the recess amount (ha) of the long block 7A and the recess amount (hb) of the middle block 7B.

  As for each dent part 9 (long dent part 9A, middle dent part 9B, short dent part 9C), the entire block 7 surface is set gradually deeper toward the center bottom part C in the tread surface 1. Each of the recesses 9 does not necessarily have the entire surface of the block 7 set to be gradually deeper toward the center bottom C. For example, a part of the block surface faces the center bottom C as shown in FIG. May be set gradually deeper, and as shown in FIG. 7, a part of the block surface may be set in a hemispherical shape.

(Action / Effect)
According to the pneumatic tire according to the present embodiment described above, the dent amount (ha, hb, hc) is set corresponding to the pitch length (A, B, C), so that the size of the block 7 is obtained. Regardless, the accumulated heat accumulated in the block 7 can be reduced, and the accumulated heat accumulated in the central bottom portion (root portion) of the block 7 can be radiated, so that steering stability is ensured. High speed performance, particularly high speed durability can be improved.

  In particular, the length (ha) of the long block 7A is set deeper (ha> hb> hc) than the amount (hb) of the middle block 7B and the depth (hc) of the short block 7C. The cage thickness is reduced at the central portion of the block (that is, the height of the central portion of the block 7 is reduced), and the area of the long block 7A that is in contact with the outside air can be increased. The accumulated heat at the center bottom C of the long block 7A can be easily dissipated, and the entire long block 7A can be radiated.

(Example)
Next, in order to further clarify the effects of the present invention, test results performed using the pneumatic tires according to the following Comparative Examples 1 and 2 and Example 1 will be described. In addition, this invention is not limited at all by these examples.

  The size of each pneumatic tire is 225 / 45R17 91Y POTENZA RE050A. In addition, each pneumatic tire has a pitch variation, and even in the same basic block, the length is different in the tire circumferential direction.

  First, the structure of the pneumatic tire according to Comparative Examples 1 and 2 and Example 1 will be briefly described. In addition, each pneumatic tire is the same conditions except a dent part demonstrated below.

  In the pneumatic tire according to Comparative Example 1, each block is not provided with a recess. Moreover, in the pneumatic tire according to the comparative example 2, all the blocks are provided with the recessed portions having the same depth. Furthermore, in the pneumatic tire according to Example 1, as in the above-described embodiment, there is provided a dent portion in which the dent amount is set corresponding to the pitch length of each block.

High speed durability and steering stability of the pneumatic tires according to Comparative Examples 1 and 2 and Example 1 will be described with reference to Table 1.

<High speed durability>
In the high-speed durability test, ECE-No. The test was carried out under the conditions defined in No.30. Each pneumatic tire is mounted on a drum testing machine, and the drum rotation speed is increased step by step, resulting in failure of each pneumatic tire (for example, chunk-out (burring of rubber lump) or burst of tread). The level was evaluated. The higher the speed level, the better the high-speed durability.

  As a result, it was found that the pneumatic tire according to Example 1 was superior in high-speed durability compared to the pneumatic tires according to Comparative Examples 1 and 2.

<Steering stability>
In the steering stability test, each pneumatic tire was mounted on a vehicle, and the driving stability such as turning ability and lane changeability when traveling on a test course was evaluated by a professional driver (maximum 10 points). The larger the index, the better the steering stability.

  As a result, it was found that the pneumatic tire according to Example 1 was superior in high-speed durability to the pneumatic tire according to Comparative Example 2.

<Comprehensive evaluation>
The pneumatic tire according to Example 1 is different from the pneumatic tires according to Comparative Examples 1 and 2 in that each block (particularly, the center bottom portion of the long block) without breaking the ground balance with respect to different sizes of the blocks. ) Is easily dissipated. For this reason, it was found that high-speed performance, particularly high-speed durability, can be improved while ensuring steering stability.

(Other embodiments)
As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention.

  Specifically, although the pneumatic tire according to the present embodiment has been described as a general radial tire including a bead portion, a carcass layer, a belt layer, and a tread portion (not shown), the present invention is not limited thereto. It may be a tire other than a radial tire (for example, a bias tire).

  Further, the pneumatic tire according to the present embodiment has been described as being mounted on a passenger car. However, the present invention is not limited to this, and the present invention is not limited to such a vehicle (for example, heavy duty tires such as buses and trucks). It may be worn.

  From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

It is an expanded view which shows the tread pattern of the pneumatic tire which concerns on this Embodiment. It is a perspective view and sectional view showing a long block formed in a pneumatic tire concerning this embodiment. It is a perspective view and sectional view showing an inside block formed in a pneumatic tire concerning this embodiment. It is a perspective view and sectional view showing a short block formed in a pneumatic tire concerning this embodiment. It is a front comparison figure which shows the long block, medium block, and short block formed in the pneumatic tire which concerns on this Embodiment. It is the perspective view and sectional drawing which show the example of a change of the block formed in the pneumatic tire which concerns on this Embodiment (the 1). It is the perspective view and sectional drawing which show the example of a change of the block formed in the pneumatic tire which concerns on this Embodiment (the 2).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Tread surface 3 ... Circumferential groove 5 ... Width direction groove 7 ... Block 7A ... Long block 7B ... Middle block 7C ... Short block 9 ... Depression 9A ... Long dent 9B ... Medium dent 9C ... Short dent

Claims (3)

In the tread surface, a pneumatic tire having a plurality of blocks formed by a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of width grooves extending in the tread width direction,
The plurality of blocks have dents that are recessed inward in the tire radial direction on the tread surface.
The pneumatic tire according to claim 1, wherein a dent amount indented inward in the tire radial direction in each dent portion is set corresponding to a pitch length which is a length in the tire circumferential direction.   2. The recess amount of the long block having the longest pitch length among the plurality of blocks is set deeper than the recess amount of the short block having the shortest pitch length among the plurality of blocks. Pneumatic tire described in 2.   3. The pneumatic tire according to claim 1, wherein the recessed portion is gradually set deeper toward a center bottom portion of the tread surface.

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