JP4943711B2 - 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, various proposals have been made on pneumatic tires that improve steering stability on wet road surfaces and icy and snowy road surfaces, in particular, braking performance. For example, a pneumatic tire is disclosed 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 a block defined by a plurality of circumferential grooves and a plurality of width grooves. (For example, refer to Patent Document 1).

In this pneumatic tire, a plurality of narrow holes absorb water, snow, etc., thereby preventing the formation of water and snow layers on the contact surface (between the tread tread and the road surface). Improves braking performance at
Japanese Patent Application Laid-Open No. Sho 62-55202 (first page-second page, FIG. 1)

  However, in the conventional pneumatic tire described above, the braking performance on the wet road surface and the icy and snow road surface is improved, but since the narrow holes are arranged on the entire surface of the block, the rigidity of the entire block is reduced, There was a problem that the braking performance on the dry road surface was lowered.

  Therefore, an object of the present invention is to provide a pneumatic tire that can improve the braking performance on a dry road surface while ensuring steering stability on a wet road surface or an icy and snowy road surface.

  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 end narrows are narrow holes arranged at the front end portion and the rear end portion in the tire circumferential direction in the block. The gist of the opening portion of the hole is smaller than the opening portion of the central narrow hole, which is a thin hole disposed in the center portion in the tire circumferential direction in the block.

  According to such a feature, if the opening portion of the end narrow hole is smaller than the opening portion of the central thin hole, when the block tries to collapse due to input (load) from the tire circumferential direction, this input is In comparison, the end narrow holes arranged at the front end portion and the rear end portion, which are larger, are crushed, and the deformation of the block can be suppressed. Thereby, the rigidity of a block improves and the braking performance on a dry road surface can be improved.

  In addition, when the input from the tire circumferential direction applied to the front end portion and the rear end portion is reduced, the end narrow holes arranged at the front end portion and the rear end portion are restored (recovered) to the original state. It is possible to ensure the handling stability on snowy and snowy road surfaces.

  The gist of the second feature of the present invention is that the end narrow holes are arranged at the outer ends in the tread width direction in the block (that is, both end portions of the block).

  According to such a feature, when the end narrow hole is arranged at the outer end portion, when the block tries to collapse due to the input from the tread width direction, the input becomes larger at the outer end portion than the center portion. The arranged end narrow hole is crushed and deformation of the block can be suppressed. Thereby, the rigidity of a block can improve and it can improve the braking performance and steering stability on a dry road surface.

  The gist of the third feature of the present invention is that the end narrow holes are arranged in one row with respect to the tread width direction or the tire circumferential direction.

  If the end narrow holes are arranged in a plurality of rows in the tread width direction or the tire circumferential direction, the number (area) of the central thin holes is reduced, and steering stability on wet road surfaces and ice / snow road surfaces is reduced. There are cases where it cannot be secured.

  The gist of the fourth feature of the present invention is that the end narrow hole rows, which are adjacent rows of the end thin holes, are arranged substantially parallel to the edge of the block. Here, “substantially parallel” refers to a range in which the end narrow hole row is up to ± 20 degrees with respect to the edge of the block.

  According to such a feature, the end narrow hole row is arranged substantially parallel to the edge of the block, so that the input (load) applied to the block and the row where the end thin hole is collapsed (that is, the end narrow hole row). Are substantially parallel, so that the rigidity of the entire block can be kept uniform. Note that if the input applied to the block and the row where the end narrow holes are crushed are not substantially parallel, the rigidity of the entire block becomes non-uniform, and uneven wear or the like may occur.

  The gist of the fifth feature of the present invention is that at least one of the end narrow hole or the central narrow hole is formed in a substantially cylindrical shape. Here, “substantially cylindrical” refers to a shape having no corners, and includes an ellipse and the like.

  According to this feature, since the end narrow hole is formed in a substantially cylindrical shape, it becomes easier to be crushed than those having corners (for example, quadrangular prisms), so that the braking performance on the dry road surface is improved. Further improvement can be achieved.

  In addition, since the central narrow hole is substantially cylindrical, it is easier to absorb and discharge water and snow generated on wet road surfaces and icy and snow road surfaces than those with corners (for example, square pillars). Steering stability on the road surface and icy and snowy road surface can be improved.

  A sixth feature of the present invention is that the opening portion of the end narrow hole is 45 to 65% with respect to the opening portion of the central thin hole.

  If the opening of the end narrow hole is smaller than 45% with respect to the opening of the central thin hole, water generated on the wet road surface and the ice / snow road surface even if the input applied to the vicinity of the end thin hole is small. It may be difficult to absorb snow and snow, and it may not be possible to ensure steering stability on wet or icy snow surfaces.

  Further, if the opening portion of the end narrow hole is larger than 65% with respect to the opening portion of the central thin hole, it becomes difficult to ensure the rigidity of the entire block, and the braking performance on the dry road surface is improved. It may not be possible.

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

  According to this feature, the depth (Ha) of the end narrow hole is shallower than the depth (Hb) of the central narrow hole, so that the depth of the end narrow hole (Ha) is the depth of the central thin hole ( The rigidity of the entire block can be improved as compared with the case where it is equal to or higher than Hb), and the braking performance on the dry road surface can be further improved.

  The eighth feature of the present invention is that the depth (Ha) of the end narrow hole is 50 to 75% with respect to the depth (Hb) of the central narrow hole.

  If the depth (Ha) of the end narrow hole is less than 50% with respect to the depth (Hb) of the center thin hole, even if the input applied to the vicinity of the end narrow hole is reduced, the wet road surface or It may be difficult to absorb water and snow generated on an icy and snowy road surface, and it may not be possible to ensure steering stability on a wet or icy and snowy road surface.

  Further, if the depth (Ha) of the end narrow hole is larger than 75% with respect to the depth (Hb) of the central narrow hole, it becomes difficult to ensure the rigidity of the entire block, and the dry road surface In some cases, it is not possible to improve the braking performance.

  According to the present invention, since the opening portion of the end narrow hole is smaller than the opening portion of the central thin hole, the braking performance on the dry road surface is improved while ensuring the steering stability on the wet road surface and the ice / snow road surface. be able to.

  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, FIG. 2 is a partially enlarged view of a block provided in the pneumatic tire according to the present embodiment, and FIG. FIG. 3 is a cross-sectional view (cross-sectional view taken along line AA in FIG. 2) of a block provided in the pneumatic tire according to the present embodiment.

  Here, the pneumatic tire 1 according to the present embodiment is assumed to be a general radial tire including a bead portion, a carcass layer, and a belt layer (not shown).

  As shown in FIGS. 1 and 2, in the pneumatic tire 1, 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 on the tread surface TS. A plurality of fine holes 9 extending from the tread tread surface TS toward the inner side in the tire radial direction are arranged in the block 7 partitioned by.

  The narrow hole 9 has an end narrow hole 9a, which is a narrow hole 9 disposed in the front end portion 11A and the rear end portion 11B in the tire circumferential direction in the block 7, and a center in the tire circumferential direction in the block 7. It is comprised by the center thin hole 9b which is the thin hole 9 arrange | positioned at the part 11C.

  Specifically, the opening portion of the end narrow hole 9a is smaller than the opening portion of the central thin hole 9b. The end narrow hole 9a and the central narrow hole 9b are formed in a substantially cylindrical shape.

  Further, the end narrow holes 9a are arranged in one row with respect to the tread width direction in order to ensure steering stability on a wet road surface or an ice / snow road surface. The end narrow hole row 13, which is an adjacent row of the end narrow holes 9 a, is arranged substantially parallel to the edge of the block 7 (the front edge 7 a and the rear edge 7 b) in order to keep the rigidity of the entire block 7 uniform. ing.

  Here, it is preferable that the opening part (namely, inner diameter) of the end narrow hole 9a is 45 to 65% with respect to the opening part (namely, inner diameter) of the central narrow hole 9b.

  If the inner diameter of the end narrow hole 9a is smaller than 45% with respect to the inner diameter of the central thin hole 9b, even if the input applied to the vicinity of the end narrow hole 9a is reduced, it occurs on the wet road surface and the ice / snow road surface. It may be difficult to absorb water and snow, and it may not be possible to ensure steering stability on wet or icy road surfaces.

  Further, if the inner diameter of the end narrow hole 9a is larger than 65% with respect to the inner diameter of the central narrow hole 9b, it becomes difficult to ensure the rigidity of the entire block 7, and the braking performance on the dry road surface is improved. It may not be possible to

  Moreover, as shown in FIG. 3, the depth (Ha) of the end narrow hole 9a is shallower than the depth (Hb) of the central thin hole 9b. The depth (Ha) of the end narrow hole 9a is preferably 50 to 75% with respect to the depth (Hb) of the central thin hole 9b.

  If the depth (Ha) of the end narrow hole 9a is smaller than 50% with respect to the depth (Hb) of the central narrow hole 9b, even if the input applied to the vicinity of the end narrow hole 9a is small, In some cases, it is difficult to absorb water and snow generated on the wet road surface and the icy and snowy road surface, and the steering stability on the wet road surface and the icy and snowy road surface cannot be ensured.

  Further, if the depth (Ha) of the end narrow hole 9a is larger than 70% with respect to the depth (Hb) of the central thin hole 9b, it becomes difficult to ensure the rigidity of the entire block 7; There are cases where the braking performance on the dry road surface cannot be improved.

(Action / Effect)
According to the pneumatic tire 1 which concerns on this embodiment demonstrated above, when the opening part (inner diameter) of the edge part narrow hole 9a is smaller than the opening part (inner diameter) of the center thin hole 9b, the input from a tire circumferential direction is carried out. If the block 7 is about to fall down due to (load), the end narrow holes 9a arranged in the front end portion 11A and the rear end portion 11B, where this input is larger than the center portion 11C, are crushed, and the deformation of the block 7 is suppressed. can do. Thereby, the rigidity of the block 7 can be improved and the braking performance on the dry road surface can be improved.

  Further, when the input from the tire circumferential direction applied to the front end portion 11A and the rear end portion 11B becomes smaller, the end narrow holes 9a arranged at the front end portion 11A and the rear end portion 11B return to their original states (recovered). Therefore, it is possible to ensure steering stability on wet road surfaces and icy and snowy road surfaces.

  Further, since the end narrow hole 9a is formed in a substantially cylindrical shape, the end narrow hole 9a is easily crushed as compared with those having a corner (for example, a quadrangular prism), so that the braking performance on the dry road surface is further improved. be able to.

  Further, since the central thin hole 9b is formed in a substantially cylindrical shape, it absorbs and discharges water and snow generated on the wet road surface and the icy / snow road surface as compared with those having a corner (for example, a square pillar). Therefore, it is possible to improve the handling stability on wet roads and icy and snowy roads.

  Further, since the depth (Ha) of the end narrow hole 9a is shallower than the depth (Hb) of the central thin hole 9b, the depth (Ha) of the end thin hole 9a is reduced to the depth of the central thin hole 9b ( The rigidity of the entire block 7 can be improved as compared with the case where it is equal to or greater than Hb), and the braking performance on the dry road surface can be further improved.

(Example of change)
In the above-described embodiment, the end narrow hole 9a has been described as being disposed at the front end portion 11A and the rear end portion 11B in the tire circumferential direction in the block 7, 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. 4 is a partially enlarged view of a block provided in a pneumatic tire according to a modified example. As shown in FIG. 4, the end narrow hole 9a is arranged at the outer end 11D in the tread width direction in the block 7 (that is, the both ends of the block 7) in addition to the front end 11A and the rear end 11B. Has been.

  Further, the end narrow holes 9a are arranged in one row with respect to the tread width direction and the tire circumferential direction in order to ensure steering stability on a wet road surface or an ice / snow road surface. In order to keep the rigidity of the entire block 7 uniform, the end narrow hole row 13 which is a row in which the end narrow holes 9a are adjacent to each other is connected to the edges of the block 7 (the front edge 7a, the rear edge 7b, and the end edge 7c). They are arranged substantially in parallel.

  According to the pneumatic tire 1 according to such a modified example, the end narrow hole 9a is arranged at the outer end portion 11D in addition to the front end portion 11A and the rear end portion 11B. If the block tries to collapse due to the input, the end narrow hole 9a disposed at the outer end 11D where the input is larger than the central portion 11C is crushed, and the deformation of the block 7 can be suppressed. As a result, the rigidity of the block 7 is improved, and the braking performance and steering stability on the dry road surface can be improved.

[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 end narrow hole 9a and the center thin hole 9b have been described as being formed in a substantially cylindrical shape, but the present invention is not limited to this, and at least one of the end narrow hole 9a or the center thin hole 9b is not limited thereto. May be formed in a substantially cylindrical shape. Further, the end narrow hole 9a and the central narrow hole 9b are not necessarily formed in a substantially cylindrical shape, and may be one having a corner (for example, a quadrangular prism).

  Furthermore, although the depth (Ha) of the end narrow hole 9a has been described as shallower than the depth (Hb) of the central thin hole 9b, the depth is not limited to this, and the depth of the central thin hole 9b is not limited thereto. It may be equal to or greater than (Hb).

  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 Example 1 and Example 1 will be described. In addition, the data regarding each pneumatic tire were measured on the conditions shown below.

・ Tire size: 195 / 65R15
・ Wheel size: 15 × 6JJ
・ 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 tires according to Comparative Example 1 and Example 1 will be described with reference to Table 1 and the drawings. The configuration other than the narrow hole is the same.

  As shown in Table 1 and FIG. 5, in the pneumatic tire 100 according to the comparative example 1, on the tread surface TS, a plurality of circumferential grooves 103 extending in the tire circumferential direction and a plurality of grooves extending in the tread width direction. A plurality of narrow holes 109 extending from the tread surface toward the inner side in the tire radial direction are arranged in the block 107 partitioned by the width direction groove 105.

  In the pneumatic tire 100 according to the comparative example 1, the narrow hole 109 is formed in a substantially cylindrical shape. Further, in the pneumatic tire 100 according to Comparative Example 1, the inner diameter of the narrow hole 109 (that is, the end narrow hole and the central thin hole) is set to “2 mm”.

  The pneumatic tire 1 according to Example 1 is the one shown in FIGS. 1 and 2. In the pneumatic tire 1 according to the first embodiment, the inner diameter of the end narrow holes 9a disposed at the front end portion 11A and the rear end portion 11B is set to “1 mm”, and the center disposed at the center portion 11C. The inner diameter of the narrow hole 9b is set to “2 mm”.

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

<Brake performance (dry road surface)>
Each pneumatic tire is mounted on a vehicle, and the vehicle equipped with the pneumatic tire 100 according to Comparative Example 1 is running at a speed of 25 km / h on a dry road test course. The stop distance of the vehicle equipped with the pneumatic tire 1 according to Example 1 is indicated by an index. The larger the index, the better the braking performance.

  As a result, it was found that the pneumatic tire 1 according to Example 1 has excellent braking performance on a dry road surface because the stop distance is shorter than that of the pneumatic tire 100 according to Comparative Example 1.

<Steering stability (Ice and snow road surface)>
Each pneumatic tire is mounted on a vehicle, runs on a test course on a snowy and snowy road surface at a constant speed, and the steering stability of the vehicle on which the pneumatic tire 100 according to Comparative Example 1 is mounted is set to “100”. The steering stability of the vehicle equipped with the pneumatic tire 1 according to the above is indicated by an index. The larger the index, the better the steering stability.

  As a result, the pneumatic tire 1 according to Example 1 was found to have the same handling stability as that of the pneumatic tire 100 according to Comparative Example 1 on the snowy and snowy road surface.

  Thus, it turns out that the pneumatic tire 1 which concerns on Example 1 to which this invention was applied can improve the braking performance on a dry road surface, ensuring the steering stability on a wet road surface or an ice-snow road surface. It was.

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) 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.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,100 ... Pneumatic tire, 3,103 ... Circumferential groove, 5,105 ... Width direction groove, 7, 107 ... Block, 7a ... Front edge, 7b ... Rear edge, 7c ... End edge, 9, 109 ... Narrow hole, 9a ... end narrow hole, 9b ... center narrow hole, 11A ... front end, 11B ... rear end, 11C ... center, 11D ... outer end, 13 ... end narrow hole row, CL ... tire Equatorial Line, TS ... tread surface

Claims (7)

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 opening portion of the end narrow hole, which is the narrow hole disposed at the front end portion and the rear end portion in the tire circumferential direction in the block, is disposed at the center portion with respect to the tire circumferential direction in the block. A pneumatic tire characterized by being 45 to 65% with respect to an opening portion of a central narrow hole which is a narrow hole.   2. The pneumatic tire according to claim 1, wherein the end narrow hole is disposed at an outer end in a tread width direction in the block.   The pneumatic tire according to claim 1 or 2, wherein the end narrow holes are arranged in one row with respect to a tread width direction or a tire circumferential direction.   4. The pneumatic tire according to claim 3, wherein the end narrow hole row, which is an adjacent row of the end thin holes, is disposed substantially parallel to an edge of the block.   The pneumatic tire according to any one of claims 1 to 4, wherein at least one of the end narrow hole or the central thin hole is formed in a substantially cylindrical shape. The pneumatic tire according to any one of claims 1 to 5 , wherein a depth (Ha) of the end narrow hole is shallower than a depth (Hb) of the central thin hole. The pneumatic tire according to claim 6 , wherein a depth (Ha) of the end narrow hole is 50 to 75% with respect to a depth (Hb) of the central thin hole.

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