JP4928785B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and in particular, an air in which a plurality of fine holes extending inward in the tire radial direction from a tread surface are arranged in a block defined by a plurality of circumferential grooves and a plurality of width grooves. Related to tires.

  Conventionally, there has been disclosed a pneumatic tire in which a plurality of fine holes extending from the tread tread surface toward the inside in the tire radial direction are arranged on the entire surface of the block defined by the plurality of circumferential grooves and the plurality of width grooves. (For example, refer to Patent Document 1).

In this pneumatic tire, a plurality of fine holes absorb water, snow, etc., so that it is possible to prevent water and snow layers that occur on the ground contact surface (between the tread tread and the road surface). Steering stability on the road surface can be improved. Further, in this pneumatic tire, it is possible to further absorb water, snow, and the like by setting a plurality of small holes large.
Japanese Patent Application Laid-Open No. Sho 62-55202 (first page-second page, FIG. 1)

  However, in the conventional pneumatic tire described above, as the plurality of small holes are set large, the rigidity of the entire block is lowered, and the driving stability on the dry road surface, the wet road surface, and the ice / snow road surface is reduced. In particular, there is a problem that the braking performance on wet road surfaces and icy and snowy road surfaces decreases.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a pneumatic tire that can suppress a decrease in steering stability on a dry road surface, a wet road surface, and an icy and snowy road surface, and can improve braking performance on a wet road surface and an icy and snowy road surface. And

  In order to solve the above-described problems, the present invention has the following features. First, as a first feature of the present invention, in the tread surface, the tread is divided into blocks defined by a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of width grooves extending in the tread width direction. A pneumatic tire in which a plurality of narrow holes extending inward in the tire radial direction from the tread surface are arranged, and the length (Wa) in the tread width direction of the opening portion of the narrow hole is the tire circumference in the opening portion of the narrow hole A sipe that is longer than the length in the direction (Wb) and extends in at least one of the tread width direction or the tire circumferential direction is disposed in the block, and the depth (Ha) of the narrow hole is defined by the depth of the sipe ( It is summarized as 60 to 95% with respect to Hb).

  According to this feature, the length of the tread width direction (Wa) is longer than the length (Wb) of the tire circumferential direction, so that the opening portion of the narrow hole is a perfect circle (that is, the narrow hole is cylindrical). Compared to the case, it is easy to absorb water, snow, etc., and the edge effect (scratch effect) of the opening portion of the narrow hole can be increased. Accordingly, it is possible to suppress a decrease in steering stability on a dry road surface, a wet road surface, and an icy and snowy road surface, and it is possible to improve braking performance on a wet and icy and snowy road surface.

  The second feature of the present invention is that the longest line (DL) in the width direction connecting the longest portion (Wa) in the tread width direction is substantially perpendicular to the tire circumferential direction. Here, “substantially perpendicular” means that the widthwise longest line (DL) indicates a range of 85 to 95 degrees with respect to the tire circumferential direction.

  According to such a feature, since the longest line in the width direction (DL) is substantially perpendicular to the tire circumferential direction, it is possible to suppress a decrease in the rigidity of the block with respect to the input (load) from the tire circumferential direction. In addition, it is possible to suppress a decrease in steering stability on wet road surfaces and icy and snowy road surfaces.

  The gist of the third feature of the present invention is that the narrow hole is arranged in a block located in the tread center portion of the tread surface.

  According to such a feature, because the narrow hole is arranged in the block located in the tread center part, it is easier to absorb water and snow than when the fine hole is arranged in the block located in the tread shoulder part. It is possible to further improve the braking performance on wet road surfaces and icy and snowy road surfaces.

  The gist of the fourth feature of the present invention is that the narrow hole is disposed in at least one of a front portion or a rear portion in the tire circumferential direction in the block.

  According to such a feature, the narrow hole is arranged in at least one of the front part or the rear part in the tire circumferential direction in the block, so that the edge is smaller than the case where the fine hole is arranged in the central part in the tire circumferential direction. The effect can be increased, and a decrease in steering stability on a dry road surface, a wet road surface, or an icy and snowy road surface can be further suppressed.

  As a fifth feature of the present invention, the longest line in the width direction (DL) connecting the longest portion (Wa) in the tread width direction is the circumferential direction connecting the longest portion (Wb) in the tire circumferential direction. The gist is that it is 1.5 to 2.5 times the longest line (SL).

  If the longest line in the width direction (DL) is smaller than 1.5 times the longest line in the circumferential direction (SL), it becomes difficult to absorb and discharge water and snow, and braking on wet roads and ice and snow roads is difficult. May not be improved.

  Further, if the longest line in the width direction (DL) is larger than 2.5 times the longest line in the circumferential direction (SL), it becomes difficult to suppress a decrease in the rigidity of the block, and a dry road surface, a wet road surface, In some cases, it is not possible to suppress a decrease in handling stability on an icy and snowy road surface.

  A sixth feature of the present invention is that a sipe extending in at least one of the tread width direction or the tire circumferential direction is arranged in the block.

  According to such a feature, the sipes extending in at least one of the tread width direction or the tire circumferential direction are arranged on the block, so that water and snow can be absorbed and discharged easily, and braking performance on wet road surfaces and icy and snow road surfaces is improved. Further improvement can be achieved.

  The seventh feature of the present invention is that the depth (Ha) of the narrow hole is shallower than the depth (Hb) of the sipe.

  According to such a feature, since the depth (Ha) of the narrow hole is shallower than the depth (Hb) of the sipe, the rigidity of the block is reduced as compared with the case where the depth of the narrow hole is equal to or greater than the depth of the sipe. And a decrease in steering stability on dry road surfaces, wet road surfaces, and icy and snowy road surfaces can be further suppressed.

  The eighth feature of the present invention is that the depth (Ha) of the narrow hole is 60 to 95% with respect to the depth (Hb) of the sipe.

  If the depth (Ha) of the narrow hole is less than 60% of the sipe depth (Hb), it becomes difficult to absorb and discharge water and snow, and braking performance on wet road surfaces and icy and snow road surfaces. May not be improved.

  In addition, if the depth (Ha) of the narrow hole is greater than 95% with respect to the sipe depth (Hb), it is difficult to suppress a decrease in the rigidity of the block, resulting in a dry road surface, a wet road surface, ice and snow. In some cases, it is not possible to suppress a decrease in steering stability on the road surface.

  According to the present invention, since the length (Wa) in the tread width direction is longer than the length (Wb) in the tire circumferential direction, it is possible to suppress a decrease in steering stability on a dry road surface, a wet road surface, and an icy / snow road surface. The braking performance on wet road surfaces and icy and snowy road surfaces can be improved.

  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, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  FIG. 1 is a development view showing a tread pattern of a pneumatic tire according to the present embodiment. The pneumatic tire 1 according to the present embodiment is a general radial tire including a bead portion, a carcass layer, and a belt layer (not shown).

  As shown in FIG. 1, in the pneumatic tire 1, the tread surface is partitioned by a plurality of circumferential grooves 3 extending in the tire circumferential direction and a plurality of widthwise grooves 5 extending in the tread width direction. A plurality of narrow holes 9 extending from the tread tread surface toward the inside in the tire radial direction are arranged in the block 7.

  In the pneumatic tire 1, a sipe 11 extending in at least one of the tread width direction or the tire circumferential direction is disposed in the block 7. The sipe 11 extending in the tread width direction includes a sipe having an inclination angle of 0 degree to 45 degrees with respect to the tread width direction. The sipe 11 extending in the tire circumferential direction includes a sipe having an inclination angle with respect to the tire circumferential direction of 0 degrees to 45 degrees.

  Hereinafter, the details of the above-described narrow hole 9 will be described with reference to the drawings. FIG. 2A is a partially enlarged view of a block provided in the pneumatic tire according to the present embodiment, and FIG. 2B is arranged in a block provided in the pneumatic tire according to the present embodiment. Fig. 3 is an enlarged view of the narrow hole formed, and Fig. 3 is a cross-sectional view (A-A cross-sectional view in Fig. 2A) of a block provided in the pneumatic tire according to the present embodiment.

  As shown in FIGS. 2A and 2B, the opening portion of the narrow hole 9 is formed in an elliptical shape. The length (Wa) in the tread width direction at the opening portion of the narrow hole 9 is longer than the length (Wb) in the tire circumferential direction at the opening portion of the narrow hole 9. Further, the longest line (DL) in the width direction connecting the longest length (Wa) in the tread width direction is substantially perpendicular to the tire circumferential direction.

  Here, the longest line (DL) in the width direction connecting the longest portion (Wa) in the tread width direction is the longest line (SL) in the circumferential direction connecting the longest portion (Wb) in the tire circumferential direction. On the other hand, it is preferably 1.5 to 2.5 times.

  If the longest line in the width direction (DL) is smaller than 1.5 times the longest line in the circumferential direction (SL), it becomes difficult to absorb and discharge water and snow, and braking on wet roads and ice and snow roads is difficult. May not be improved. In addition, if the longest line in the width direction (DL) is larger than 2.5 times the longest line in the circumferential direction (SL), it becomes difficult to suppress a decrease in rigidity of the block 7, and a dry road surface or a wet road surface In some cases, it is not possible to suppress a decrease in handling stability on an icy and snowy road surface.

  Further, as shown in FIG. 3, the depth (Ha) of the narrow hole 9 is shallower than the depth (Hb) of the sipe 11. The depth (Ha) of the narrow hole 9 is preferably 60 to 95% with respect to the depth (Hb) of the sipe 11.

  If the depth (Ha) of the narrow hole 9 is smaller than 60% with respect to the depth (Hb) of the sipe 11, it becomes difficult to absorb and discharge water and snow. There are cases where the braking performance cannot be improved. Further, if the depth (Ha) of the narrow hole 9 is larger than 95% with respect to the depth (Hb) of the sipe 11, it becomes difficult to suppress a decrease in rigidity of the block 7, and a dry road surface or wet In some cases, it is not possible to suppress a decrease in steering stability on the road surface and the icy and snowy road surface.

  In addition, as shown in FIG. 1, such a narrow hole 9 makes it easier to absorb water and snow than the case where it is arranged in the block 7 located in the tread shoulder portion TE in the tread tread. It arrange | positions at the block 7 located in center part TC.

  Further, as shown in FIG. 2A, the narrow hole 9 increases the edge effect as compared with the case where the narrow hole 9 is arranged in the central portion 13A in the tire circumferential direction. And the rear portion 13C.

(Action / Effect)
According to the pneumatic tire 1 which concerns on this embodiment demonstrated above, when the length (Wa) of a tread width direction is longer than the length (Wb) of a tire circumferential direction, the opening part of the fine hole 9 is a perfect circle. Compared to the case where the narrow hole is cylindrical, water, snow, etc. can be absorbed more easily, and the edge effect (scratch effect) of the opening portion of the narrow hole 9 can be increased. Accordingly, it is possible to suppress a decrease in steering stability on a dry road surface, a wet road surface, and an icy and snowy road surface, and it is possible to improve braking performance on a wet and icy and snowy road surface.

  Moreover, since the longest line in the width direction (DL) is substantially perpendicular to the tire circumferential direction, it is possible to suppress a decrease in rigidity of the block 7 with respect to an input (load) from the tire circumferential direction, and a dry road surface or a wet road surface. In addition, it is possible to further suppress a decrease in steering stability on an icy and snowy road surface.

  Further, since the narrow hole 9 is arranged in the block 7 located in the tread center portion TC, it is easier to absorb water and snow than in the case where the fine hole 9 is arranged in the block 7 located in the tread shoulder portion TE. Therefore, it is possible to further improve the braking performance on the wet road surface and the ice / snow road surface.

  Further, since the narrow hole 9 is disposed in at least one of the front portion 13B or the rear portion 13C in the tire circumferential direction in the block 7, compared with the case where the narrow hole 9 is disposed in the central portion 13A in the tire circumferential direction. As a result, the edge effect can be increased, and a decrease in steering stability on dry road surfaces, wet road surfaces, and icy and snowy road surfaces can be suppressed.

  Further, the sipes 11 extending in at least one of the tread width direction or the tire circumferential direction are arranged in the block 7 so that water and snow can be absorbed and discharged easily, and braking performance on wet road surfaces and icy and snow road surfaces is further improved. Can be made.

  Furthermore, since the depth (Ha) of the narrow hole 9 is shallower than the depth (Hb) of the sipe 11, the rigidity of the block 7 is higher than when the depth of the narrow hole 9 is equal to or greater than the depth of the sipe 11. It is possible to suppress the decrease, and it is possible to further suppress the decrease in the steering stability on the dry road surface, the wet road surface, and the ice / snow road surface.

(Example of change)
In the above-described embodiment, the opening portion of the narrow hole 9 has been described as being formed in an elliptical shape, but can be modified as follows. In addition, the part which is different from the pneumatic tire 1 which concerns on embodiment of this invention mentioned above is mainly demonstrated.

  FIG. 4A is a partially enlarged view of the block provided in the pneumatic tire according to the modified example, and FIG. 4B is disposed in the block provided in the pneumatic tire according to the modified example. It is an enlarged view of a narrow hole.

  As shown in FIGS. 4A and 4B, the opening portion of the narrow hole 9 is formed in a polygonal shape (an octagon in FIG. 4). The length (Wa) in the tread width direction at the opening portion of the narrow hole 9 is longer than the length (Wb) in the tire circumferential direction at the opening portion of the narrow hole 9. Further, the longest line (DL) in the width direction connecting the longest length (Wa) in the tread width direction is substantially perpendicular to the tire circumferential direction.

  Further, the longest line in the width direction (DL) that connects the longest portion in the tread width direction (Wa) is the longest line in the circumferential direction (SL) that connects the longest portion in the tire circumferential direction (Wb). It is preferably 1.5 to 2.5 times. Further, the depth (Ha) of the narrow hole 9 is preferably 60 to 95% with respect to the depth (Hb) of the sipe 11.

[Other Embodiments]
Although the contents of the present invention have been disclosed through the embodiments of the present invention as described above, 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 1 according to the present embodiment has been described as a general radial tire including a bead portion, a carcass layer, and a belt layer (not shown), the pneumatic tire 1 is not limited thereto. Alternatively, a tire other than a radial tire (for example, a bias tire) may be used.

  Further, the depth (Ha) of the narrow hole 9 has been described as shallower than the depth (Hb) of the sipe 11, but is not limited to this, and is equal to or greater than the depth (Hb) of the sipe 11. It may be.

  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.

  Next, in order to further clarify the effects of the present invention, the results of tests performed using pneumatic tires according to the following comparative examples and examples will be described. In addition, the data regarding each pneumatic tire were measured on the conditions shown below.

・ Tire size: 175 / 80R14
・ Internal pressure condition: 220 kpa
・ Load condition: 3.90kN
・ Vehicle type: General passenger car (displacement 1.500cc)
The fine holes formed in the blocks provided in the pneumatic tire according to each will be described with reference to Table 1 and the drawings.

  In the pneumatic tire according to Comparative Example 1, as shown in FIG. 5, a plurality of circumferential grooves 30 extending in the tire circumferential direction and a plurality of width grooves 50 extending in the tread width direction on the tread surface. A plurality of fine holes 90 (perfect circles) extending from the tread surface toward the inner side in the tire radial direction are arranged in the block 70 partitioned by.

  In the pneumatic tire according to the comparative example 1, the opening portion of the narrow hole 90 is formed in a perfect circle. Moreover, in the pneumatic tire according to Comparative Example 1, as shown in Table 1, the longest line in the width direction (DL) and the longest line in the circumferential direction (SL) in the narrow hole 90 are set to “1 mm”.

  Moreover, the pneumatic tire according to Example 1 is the one shown in FIGS. 1 and 2. In the pneumatic tire according to Example 1, as shown in Table 1, the longest line in the width direction (DL) in the narrow hole 9 is set to “1.5 mm”, and the longest circumferential line in the thin hole 9 ( SL) is set to “1 mm”.

  Furthermore, in the pneumatic tire according to Example 2, as shown in FIG. 6, the opening portion of the narrow hole 9A is formed in an elliptical shape. In the pneumatic tire according to Example 2, as shown in Table 1, the longest line (DL) in the width direction in the narrow hole 9A is set to “2.5 mm”, and the longest line in the circumferential direction in the narrow hole 9A ( SL) is set to “1 mm”. The configuration other than the narrow hole 9A is the same as that of the pneumatic tire according to the first embodiment.

  The braking performance and steering stability of the pneumatic tires according to Comparative Example 1 and Examples 1 and 2 will be described with reference to Table 1.

<Brake performance (on ice surface)>
Each pneumatic tire is mounted on a vehicle, and a vehicle equipped with the pneumatic tire according to Comparative Example 1 is running at a speed of 25 km / h in a test course on an icy road, and after being braked, until 0 km / h. The distance of the vehicle (stop distance) was “100”, and the stop distance of the vehicle equipped with the pneumatic tires according to Examples 1 and 2 was displayed as an index. The smaller the index, the better the braking performance.

  As a result, the pneumatic tires according to Examples 1 and 2 to which the present invention is applied have a shorter stopping distance than the pneumatic tire according to Comparative Example 1, and therefore have excellent braking performance on an icy road surface. I understood.

<Brake performance (snow surface)>
Each pneumatic tire is mounted on a vehicle, and the vehicle equipped with the pneumatic tire according to Comparative Example 1 is running at a speed of 25 km / h in a test course on a snowy road until it reaches 0 km / h after being braked. The distance of the vehicle (stop distance) was “100”, and the stop distance of the vehicle equipped with the pneumatic tires according to Examples 1 and 2 was displayed as an index. The smaller the index, the better the braking performance.

  As a result, it was found that the pneumatic tires according to Examples 1 and 2 are superior in braking performance on a snowy road surface because the stopping distance is shorter than that of the pneumatic tire according to Comparative Example 1.

<Maneuvering stability (dry road surface)>
Each pneumatic tire is mounted on a vehicle, runs at a constant speed on a dry road test course, and the steering stability of the vehicle on which the pneumatic tire according to Comparative Example 1 is mounted is set to “5”. The steering stability of the vehicle equipped with the pneumatic tire according to No. 2 was displayed as an index. The larger the index, the better the steering stability.

  As a result, the pneumatic tire according to Example 1 was found to have the same handling stability as that of Comparative Example 1 on the snowy and snowy road surface. Moreover, it turned out that the pneumatic tire which concerns on Example 2 suppresses the fall of the steering stability on an ice-snow road surface.

It is an expanded view which shows the tread pattern of the pneumatic tire which concerns on this embodiment. It is a partial enlarged view of the block provided in the pneumatic tire which concerns on this embodiment. It is sectional drawing (AA sectional drawing in Fig.2 (a)) of the block provided in the pneumatic tire which concerns on this embodiment. It is a partial enlarged view of the block provided in the pneumatic tire which concerns on the example of a change. 3 is a partially enlarged view of a block provided in a pneumatic tire according to Comparative Example 1. FIG. 6 is a partially enlarged view of a block provided in a pneumatic tire according to Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,100 ... Pneumatic tire, 3,30 ... Circumferential groove | channel, 5,50 ... Width direction groove | channel, 7,70 ... Block, 9,90 ... Fine hole, 11 ... Sipe, 13A ... Center part, 13B ... Front part , 13C ... rear part, TC ... tread center part, TE ... tread shoulder part

Claims (5)

In the tread tread, the tread tread extends inward in the tire radial direction from the tread tread into a block defined by a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of width grooves extending in the tread width direction. A pneumatic tire in which a plurality of fine holes are arranged,
The length of the tread width direction of the opening of the fine hole (Wa) is rather long than the tire circumferential direction length of the opening portion of the small hole (Wb),
A sipe extending in at least one of the tread width direction or the tire circumferential direction is arranged in the block,
The pneumatic tire according to claim 1, wherein a depth (Ha) of the narrow hole is 60 to 95% with respect to a depth (Hb) of the sipe .   2. The pneumatic tire according to claim 1, wherein a longest line (DL) in a width direction connecting a portion having the longest length (Wa) in the tread width direction is substantially perpendicular to the tire circumferential direction.   The pneumatic tire according to claim 1 or 2, wherein the narrow hole is arranged in the block located in a tread center portion on the tread surface.   The pneumatic tire according to any one of claims 1 to 3, wherein the narrow hole is disposed in at least one of a front portion or a rear portion in a tire circumferential direction in the block.   The longest line (DL) in the width direction connecting the longest portion (Wa) in the tread width direction is the longest line (SL) in the circumferential direction connecting the longest portion (Wb) in the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 4, wherein the pneumatic tire is 1.5 to 2.5 times.

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