JP5621333B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire. In particular, the present invention relates to a pneumatic tire having a tread surface in which holes are formed.

  In order to improve the performance on ice, it is preferable to increase the edge length of the land portion of the tread pattern. On the other hand, in order to improve the tire performance on the dry road surface, it is preferable to increase the rigidity of the land portion. However, if the edge length of the land portion of the tread pattern is increased, the rigidity of the land portion is lowered, and therefore it is difficult to achieve both the increase of the edge length of the land portion and the improvement of the rigidity of the land portion.

  To date, many technologies have been developed to improve the rigidity of the block land while ensuring the scratching effect by the pattern edge in order to achieve both on-ice performance and dry performance. In addition, a technology has been developed to provide a hole in the tread surface to secure the rigidity of the land portion while obtaining a water removal effect on ice. Techniques for improving various performances of the tire by simply providing a large number of holes on the tread surface include the following.

  Patent Document 1 has a tread pattern based on a block pattern, and the block surface constituting the block pattern has a diameter of 0.5 mm to 2 mm and a depth of 50% to 100% of the main groove depth. A studless tire is disclosed in which a plurality of holes are opened so as to be 0.5% to 10% with respect to the block surface area. According to the tire, by providing a plurality of holes in the block surface, it is possible to improve the ground contact property of the tread surface mainly due to the occurrence of water absorption and to improve the running performance on icy and snowy roads.

  In Patent Document 2, a pair of sidewalls and a tread extending over both sidewalls are connected to the toroidal, a plurality of circumferential grooves extending in parallel to each other at predetermined intervals in the axial direction on the tread, and these circumferential grooves. And a plurality of lateral grooves arranged at substantially equal intervals in the circumferential direction and independent blocks partitioned by these groove groups, the tire is provided at least in the vicinity of an edge along the lateral groove of the block. There is disclosed a pneumatic tire that suppresses uneven wear by providing a plurality of small holes extending inward in the radial direction at predetermined intervals. According to the tire, the rigidity of the edge along the lateral groove of the block is reduced, and as a result, the entire block receives the shearing external force in the front-rear direction, and uneven wear in the block can be effectively suppressed. It is said that.

  In Patent Document 3, a pair of second sipes extending in a direction intersecting with the first sipes is disposed in at least one block land portion, and virtually partitioned by the extension lines of the first and second sipes. A pneumatic tire having a plurality of small holes in the sub-block land portion is disclosed. According to the tire, as a result of suppressing the bending deformation of the block land portion, the performance on ice and the performance on snow can be made compatible at a high level on the premise of maintaining the block rigidity of the tire.

Japanese Patent Laid-Open No. 03-208705 JP 04-85108 A JP 2008-30656 A

  Each of the techniques disclosed in Patent Documents 1 to 3 improves the performance of the tire by providing holes on the tread surface, and simply defines the density of the holes relative to the block, or For example, a small hole is simply provided in the block edge along the direction groove. However, in these techniques, when a large number of holes are provided on the tread surface, not only the rigidity of the land portion is lowered, but the holes may be crushed at the time of grounding, and a sufficient water removal effect may not be obtained. As described above, the techniques disclosed in Patent Document 1 to Patent Document 3 have a relatively simple arrangement of holes, so that it is difficult to achieve both high land rigidity and water removal effect. There is a possibility that the balance between the performance and the dry performance cannot be sufficiently achieved.

  This invention is made | formed in view of the said situation, Comprising: It aims at providing the pneumatic tire which aimed at coexistence with performance on ice and dry performance.

  In order to solve the above-described problems and achieve the object, the pneumatic tire of the present invention includes at least two hole groups each having three or more holes on a tread surface, and any two of the hole groups in the hole groups are included. Regarding the hole i and the hole j, in a plan view, the radius of the circumscribed circle Ci of the hole i is ri, the radius of the circumscribed circle Cj of the hole j is rj, and the distance between the centers of both the circumscribed circles Ci and Cj is dj. In this case, for every hole i, at least one hole j satisfying dij ≦ (ri + rj) × 2 exists in the hole group to which the hole belongs, and at least one hole k is different from the hole k. There is at least one hole l belonging to the hole group and having a shortest distance from the hole k of 1.5 mm to 10.0 mm.

  This pneumatic tire has at least two hole groups composed of three or more holes, and the radius of the circumscribed circle Ci of the hole i is set to ri for any two holes i and j in the hole group. When the radius of the circumscribed circle Cj of the hole j is rj and the distance between the centers of the circumscribed circles Ci and Cj is dij, dij ≦ (ri + rj) There is at least one hole j satisfying × 2. This means that for every hole i, there is at least one hole j at a relatively close position. As described above, when the holes i and j are concentrated in a narrow area, the individual holes i and j are compared with the case where one hole having the same volume as the total volume of the dense holes is formed. Since the diameter of is small and is not easily crushed, the collapse of the holes i and j can be suppressed. As a result, the rigidity of the land portion provided in the tread portion can be sufficiently ensured without reducing the water removal effect.

  Further, the pneumatic tire has at least one hole l that belongs to a hole group different from the hole k for at least one hole k and that has a shortest distance from the hole k of 1.5 mm to 10.0 mm. To exist. Thus, by disposing another group of holes at a predetermined interval, the water removal effect can be effectively obtained while sufficiently securing the rigidity of the entire tread land portion. For this reason, compared with the case where one hole having the same volume as the total volume of all the holes included in the plurality of hole groups arranged at a predetermined interval is formed, it is provided in the tread portion without reducing the water removal effect. The rigidity of the land portion thus obtained can be sufficiently secured.

  By making the shortest distance 1.5 mm or more, it is possible to sufficiently secure the distance between the hole groups, so that it is possible to suppress a local decrease in rigidity of the land portion provided in the tread portion. it can. In addition, by setting the shortest distance to 10.0 mm or less, a sufficient number of hole groups can be arranged in the land portion provided in the tread portion, and the water removal effect can be sufficiently ensured.

  As described above, the pneumatic tire according to the present invention makes the holes i and j dense in a narrow area within one hole group, and the holes k and l belonging to the different hole groups respectively. It was completed by arranging it at intervals. For this reason, it is the same as all holes included in a plurality of hole groups arranged at a predetermined interval as well as a case where one hole having the same volume as a plurality of holes densely packed in the hole group is formed. The rigidity of the land portion provided in the tread portion can be sufficiently ensured without lowering the water removal effect as compared with the case where one hole with a volume is formed. Therefore, according to this pneumatic tire, both on-ice performance and dry performance can be achieved.

  In the pneumatic tire of the present invention, it is desirable that for all the holes i in the hole group, at least two holes j satisfying dij ≦ (ri + rj) × 2 exist in the hole group to which the hole belongs. This means that for every hole i, there are at least two holes j at relatively close positions. According to this pneumatic tire, in the vicinity of all the holes i, it is very remarkably suppressed that the self or other holes are deformed and crushed. Thereby, the water removal effect and the rigidity of the tread land portion can be further enhanced, and as a result, the on-ice performance and the dry performance can be further enhanced.

  In the pneumatic tire of the present invention, it is desirable that the volume of at least one hole is different from the volume of other holes in at least one hole group. According to this pneumatic tire, when each hole is used as a reference, not only the water removal effect by each hole, but also the rigidity of the faithful tread rubber existing around each hole can be set as appropriate. For this reason, the rigidity of the land part provided in the tread part and the water removal effect can be locally increased or decreased. As a result, the balance between the rigidity and the water removal effect in the hole group can be adjusted efficiently, and consequently the balance between the performance on ice and the dry performance can be adjusted.

  In the pneumatic tire of the present invention, it is desirable that the radius of the circumscribed circle of all the holes in the hole group is 0.2 mm or more and 1.0 mm or less. According to this pneumatic tire, by setting the radius to 0.2 mm or more, it is possible to sufficiently suppress the crushing of each hole and obtain a water removal effect. Moreover, by making the said radius 1.0 mm or less, it can fully suppress that each hole deform | transforms and can suppress the fall of rigidity. As a result, the water removal effect and the rigidity of the tread land portion can be further increased, and as a result, the on-ice performance and the dry performance can be further enhanced.

In the pneumatic tire of the present invention, it is desirable that the total volume of the holes in the hole group is 10 mm ³ or less. According to this pneumatic tire, a large number of holes having a small volume can be arranged by reducing the volume of the entire hole group. For this reason, each hole can be sufficiently prevented from being deformed and crushed, the water removal effect and the rigidity of the tread land portion can be further enhanced, and the on-ice performance and the dry performance can be further enhanced. .

  In the pneumatic tire of the present invention, it is preferable that a plurality of sipes are formed in a land portion provided in a tread portion, and the hole group is formed in a small block divided by the sipes. According to this pneumatic tire, the water removal effect by the hole group and the water removal effect by the sipe formed in the land portion of the tread portion are combined, and in particular, since a high water removal effect is obtained, the performance on ice is further enhanced. be able to.

  Further, in the pneumatic tire of the present invention, a plurality of sipes are formed in the block land portion provided in the tread portion, and the arrangement region of the hole group is on the stepping side of the block land portion when the tire rotates. Desirably, the region is at least one of the region and the region on the kicking side. According to this pneumatic tire, the water absorption effect at the time of tire rotation increases, and as a result, the performance on ice can be further enhanced.

  The pneumatic tire according to the present invention can achieve both on-ice performance and dry performance.

FIG. 1 is a plan view illustrating a main part of an example of a tread portion of the pneumatic tire according to the first embodiment. FIG. 2 is an enlarged perspective view of the hole group shown in FIG. FIG. 3A is a plan view illustrating a variation of an arrangement mode of holes constituting a hole group formed in a tread portion of the pneumatic tire according to the first embodiment. FIGS. 3-2 is a top view which shows the variation about the arrangement | positioning aspect of the hole which comprises the hole group formed in the tread part of the pneumatic tire which concerns on Embodiment 1. FIGS. FIG. 3-3 is a plan view illustrating a variation regarding an arrangement mode of holes constituting a hole group formed in the tread portion of the pneumatic tire according to the first embodiment. FIG. 4-1 is a plan view illustrating a variation of holes forming a hole group formed in the tread portion of the pneumatic tire according to the first embodiment, and a dotted line indicates a circumscribed circle of a solid line figure. FIG. 4-2 is a plan view illustrating a variation of the holes constituting the hole group formed in the tread portion of the pneumatic tire according to the first embodiment, and a dotted line indicates a circumscribed circle of a solid line figure. FIG. 4-3 is a plan view illustrating a variation of the holes constituting the hole group formed in the tread portion of the pneumatic tire according to the first embodiment, and a dotted line indicates a circumscribed circle of a solid line figure. FIGS. 4-4 is a top view which shows the variation of the hole which comprises the hole group formed in the tread part of the pneumatic tire which concerns on Embodiment 1, and a dotted line shows the circumscribed circle of a solid line figure. FIGS. 4-5 is a top view which shows the variation of the hole which comprises the hole group formed in the tread part of the pneumatic tire which concerns on Embodiment 1, and a dotted line shows the circumscribed circle of a solid line figure. FIGS. 4-6 is a top view which shows the variation of the hole which comprises the hole group formed in the tread part of the pneumatic tire which concerns on Embodiment 1, and a dotted line shows the circumscribed circle of a solid line figure. FIGS. 4-7 is a top view which shows the variation of the hole which comprises the hole group formed in the tread part of the pneumatic tire which concerns on Embodiment 1, and a dotted line shows the circumscribed circle of a solid line figure. FIG. 5 is an enlarged plan view of the hole group shown in FIG. FIG. 6 is a plan view illustrating a main part of an example of a tread portion of the pneumatic tire according to the second embodiment. FIG. 7 is an enlarged perspective view of the hole group shown in FIG. FIGS. 8-1 is a top view which shows the variation about the arrangement | positioning aspect of the hole which comprises the hole group formed in the tread part of the pneumatic tire which concerns on Embodiment 2. FIGS. FIGS. 8-2 is a top view which shows the variation about the arrangement | positioning aspect of the hole which comprises the hole group formed in the tread part of the pneumatic tire which concerns on Embodiment 2. FIGS. FIG. 9 is an enlarged plan view of the hole group shown in FIG. FIG. 10 is a plan view illustrating a main part of an example of a tread portion of the pneumatic tire according to the third embodiment. FIG. 11 is a plan view illustrating a main part of an example of a tread portion of the pneumatic tire according to the fourth embodiment. FIG. 12 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention. FIG. 13 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following description. In addition, constituent elements in the following description include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. Moreover, the structure disclosed below can be combined suitably. In the following description, the tire circumferential direction refers to a circumferential direction centered on the tire rotation axis, and the tire width direction refers to a direction parallel to the tire rotation axis. Further, the tire radial direction means a direction orthogonal to the pneumatic tire rotation axis, the tire radial direction outer side means a side away from the tire rotation axis in the tire radial direction, and the tire radial direction inner side means in the tire radial direction. The side facing the tire rotation axis.

[Embodiment 1]
FIG. 1 is a plan view illustrating a main part of an example of a tread portion of the pneumatic tire according to the first embodiment. In the example shown in the figure, the tread portion 1 is provided with a plurality of circumferential grooves 2 extending substantially in the tire circumferential direction and a plurality of lateral grooves 3 communicating with two adjacent circumferential grooves 2. Yes. As a result, a large number of block land portions 4 are defined in the tread portion 1.

  A plurality of hole groups are formed in the block land portion 4 formed in this way. In the present embodiment, three hole groups are formed in one block land portion 4 in the tire circumferential direction, and three hole groups are also formed in the tire width direction, for a total of nine hole groups. ing. For example, taking the adjacent hole groups 5 and 6 shown in FIG. 1 as an example, the hole group 5 (hole group 6) has three holes 5a, 5b and 5c (three holes 6a and 6b) that are circular in plan view. 6c). Moreover, the hole group 5 (hole group 6) has an arrangement shape that becomes an equilateral triangle when the centers of the holes 5a to 5c (holes 6a to 6c) are connected.

  FIG. 2 is an enlarged perspective view of the hole group shown in FIG. As shown in FIG. 2, the holes 5a, 5b, 5c (holes 6a, 6b, 6c) constituting the hole group 5 (hole group 6) are all cylindrical outside in the tire radial direction, and the tire diameter The inner side is tapered. Moreover, each hole 5a-5c (each hole 6a-6c) is bottomed inside the tire radial direction while opening to the tread surface. In addition, since each hole 5a-5c (each hole 6a-6c) is a taper shape in which a hole diameter becomes small gradually in the bottom part, it is suitable for improving the rigidity of a bottom part.

  In the example shown in FIG. 2, the holes 5a, 5b, 5c (holes 6a, 6b, 6c) have the same tire radial depth. The depth of each hole 5a to 5c (each hole 6a to 6c) is preferably 2 mm or more in order to obtain a sufficient water removal effect. Further, the depth of each of the holes 5a to 5c (each of the holes 6a to 6c) is preferably equal to or less than the depth of the circumferential groove 2 in order to obtain excellent durability without the hole bottom approaching the belt layer.

  In the example shown in FIG. 1, the arrangement mode of the holes 5a, 5b, and 5c (holes 6a, 6b, and 6c) is an aspect that is an equilateral triangle in a plan view, but the first embodiment is limited to such an aspect. Absent. FIGS. 3A to 3C are plan views illustrating variations of the arrangement mode of the holes constituting the hole group formed in the tread portion of the pneumatic tire according to the first embodiment. 3A to 3C, for convenience, the holes 5a to 5c are shown among the holes 5a to 5c (holes 6a to 6c). However, in the present embodiment, the holes 6a to 6c are also holes. It can be made the same shape as 5a-5c.

  As shown in FIG. 3A, the holes 5a, 5b, and 5c may be arranged such that the figure connecting the centers of the holes 5a to 5c is a triangle. Moreover, as shown to FIGS. 3-2, it can also be set as the aspect from which the figure which tied the center of each hole 5a-5c becomes a straight line. Moreover, as shown to FIGS. 3-3, the hole group 5 is comprised from four holes 5a, 5b, 5c, 5d, and it can also be set as the aspect from which the figure which tied the center of each hole 5a-5d becomes a trapezoid. . In the example shown in FIG. 3C, the tire radial depth of each hole can be the same for the holes 5a to 5d.

  In the example illustrated in FIG. 1, the holes 5a, 5b, and 5c (holes 6a, 6b, and 6c) are all circular in a plan view, but Embodiment 1 is not limited to such an aspect. FIGS. 4-1 to FIGS. 4-7 are plan views showing variations of the holes constituting the hole group formed in the tread portion of the pneumatic tire according to the first embodiment, and the dotted line shows a circumscribed circle of a solid line figure .

  As shown in these drawings, the shape of the holes constituting the hole group 5 (hole group 6) is not only circular as shown in FIG. 4-1, but also the quadrangle shown in FIG. 3 and an n-gon (n ≧ 3) including a hexagon shown in FIG. 4-4. Moreover, the shape of the hole which comprises the hole group 5 (hole group 6) shall be the star shape shown to FIGS. 4-5, the saddle shape shown to FIGS. 4-6, and the ellipse shape shown to FIGS. 4-7. You can also. In the example shown in FIG. 1, the dimensions (radius of the circumscribed circle) of the holes 5a, 5b, and 5c (holes 6a, 6b, and 6c) are all equal, but the first embodiment is not limited to such a form. The dimensions of the holes can vary at least in part. Here, the circumscribed circle refers to the circumscribed circle of the opening of each of the holes 5a to 5c (each of the holes 6a to 6c).

  On the premise of such hole arrangement mode, shape, and dimensions, the hole groups 5 and 6 further satisfy the following first and second requirements. That is, the first requirement is that for any two holes i and j in the hole groups 5 and 6, the radius of the circumscribed circle Ci of the hole i is ri and the radius of the circumscribed circle Cj of the hole j is the plan view. When the distance between the centers of rj and both circumscribed circles Ci and Cj is dij, for all the holes i, at least one hole j satisfying dij ≦ (ri + rj) × 2 is present in the hole group to which the hole belongs. It exists. Further, the second requirement is that at least one hole l belongs to a hole group different from the hole k and the shortest distance from the hole k is 1.5 mm to 10.0 mm. It exists. Here, the symbols i, j, k, and l are identifiers for identifying arbitrary holes constituting the hole groups 5 and 6, and do not indicate specific holes.

  The first requirement means that every hole i has at least one hole j at a relatively close position in the group of holes 5 and 6, and the second requirement is that at least one hole k is It means that it exists at a position relatively close to the hole l in the other hole group. Here, the relatively close positions in the first requirement are the distance between the centers dij of the circumscribed circle Ci of the hole i and the circumscribed circle Cj of the hole j, and the radius ri of the hole i and the radius rj of the hole j. The position of the hole j with respect to the hole i when satisfying that it is 2 times or less of the sum of. The relatively close position in the second requirement refers to the position of the hole l with respect to the hole k when the shortest distance between the hole k and the hole l satisfies 1.5 mm to 10.0 mm.

  FIG. 5 is an enlarged plan view of the hole groups 5 and 6 shown in FIG. As shown in FIG. 5, since the holes 5a, 5b, and 5c (holes 6a, 6b, and 6c) are all circular in a plan view, these circumscribed circles are formed in the holes 5a, 5b, and 5c (holes 6a, 6b). , 6c). Here, the radius of the circumscribed circle Ca of the hole 5a is ra, the radius of the circumscribed circle Cb of the hole 5b is rb, the radius of the circumscribed circle Cc of the hole 5c is rc, and the distance between the centers of the circumscribed circles Ca and Cb is dab, The distance between the centers of the circumscribed circles Cb and Cc is dbc, and the distance between the centers of the circumscribed circles Cc and Ca is dca. Further, the radius of the circumscribed circle Ca ′ of the hole 6a is ra ′, the radius of the circumscribed circle Cb ′ of the hole 6b is rb ′, the radius of the circumscribed circle Cc ′ of the hole 6c is rc ′, and the circumscribed circles Ca ′ and Cb ′. The distance between the centers of the circles is dab ′, the distance between the centers of the circumscribed circles Cb ′ and Cc ′ is dbc ′, and the distance between the centers of the circumscribed circles Cc ′ and Ca ′ is dca ′.

  When the hole i is the hole 5a and the hole j is the hole 5b and the hole 5c, as shown in FIG. 5, with respect to the hole 5a, in relation to the hole 5b and the hole 5c, dab ≦ (ra + rb) × 2 There is a hole 5b that satisfies this condition, and a hole 5c that satisfies dca ≦ (rc + ra) × 2. When the hole i is the hole 5b and the hole j is the hole 5c and the hole 5a, the hole 5b similarly satisfies dbc ≦ (rb + rc) × 2 in the relationship between the hole 5c and the hole 5a. The hole 5c and the hole 5a satisfying dab ≦ (ra + rb) × 2 exist. Further, when the hole i is the hole 5c and the hole j is the hole 5a and the hole 5b, similarly, the hole 5c satisfies dca ≦ (rc + ra) × 2 in relation to the hole 5a and the hole 5b. The hole 5a and the hole 5b satisfying dbc ≦ (rb + rc) × 2 exist.

  Similarly, when the hole i is the hole 6a and the hole j is the hole 6b and the hole 6c, as shown in FIG. 5, the hole 6a has a relationship dab ′ ≦ ( There is a hole 6b satisfying ra ′ + rb ′) × 2 and a hole 6c satisfying dca ′ ≦ (rc ′ + ra ′) × 2. When the hole i is the hole 6b and the hole j is the hole 6c and the hole 6a, the hole 6b is similarly dbc ′ ≦ (rb ′ + rc ′) in relation to the hole 6c and the hole 6a. There is a hole 6c satisfying × 2 and a hole 6a satisfying dab ′ ≦ (ra ′ + rb ′) × 2. Further, when the hole i is the hole 6c and the hole j is the hole 6a and the hole 6b, the hole 6c is similarly dca ′ ≦ (rc ′ + ra ′) in relation to the hole 6a and the hole 6b. There is a hole 6a satisfying × 2 and a hole 6b satisfying dbc ′ ≦ (rb ′ + rc ′) × 2.

  The pneumatic tire having a tread surface in which such hole groups 5 and 6 are formed has all the holes, and in the example shown in FIG. 1, the holes 5 a, 5 b, 5 c, 6 a, 6 b, and 6 c are the hole group 5. , 6 having at least one hole at a relatively close position, and satisfying the first requirement.

  As for the hole 5 a, the holes 5 b and 5 c are holes located at relatively close positions in the hole group 5. In this case, as seen from the relationship between the holes 5a and 5b, as shown in FIG. 2, the holes 5a and 5b are densely packed in a narrow region, and the individual holes 5a and 5b are not easily crushed. For this reason, falling of the holes 5a and 5b can be suppressed. As a result, the rigidity of the land portion provided in the tread portion is sufficiently reduced without deteriorating the water removal effect as compared with the case where one hole having the same volume as the total volume of the dense holes 5a and 5b is formed. Can be secured. Further, as seen from the relationship between the holes 5a and 5c, as shown in FIG. 2, the holes 5a and 5c are densely packed in a narrow region, and the individual holes 5a and 5c are not easily crushed. For this reason, falling of the holes 5a and 5c can be suppressed. As a result, compared with the case where one hole having the same volume as the total volume of the dense holes 5a and 5c is formed, the rigidity of the land portion provided in the tread portion is sufficiently reduced without reducing the water removal effect. Can be secured.

  Similarly, regarding the hole 5 b, the holes 5 c and 5 a are holes located at relatively close positions in the hole group 5. In this case, as seen from the relationship between the holes 5b and 5c, as shown in FIG. 2, the holes 5b and 5c are densely packed in a narrow region, and the individual holes 5b and 5c are not easily crushed. For this reason, falling of the holes 5b and 5c can be suppressed. As a result, compared with the case where one hole having the same volume as the total volume of the dense holes 5b and 5c is formed, the rigidity of the land portion provided in the tread portion is sufficiently reduced without reducing the water removal effect. Can be secured. Further, when viewed from the relationship between the hole 5b and the hole 5a, as shown in FIG. 2, the holes 5b and 5a are densely packed in a narrow region, and the individual holes 5b and 5a are not easily crushed. For this reason, falling of the holes 5b and 5a can be suppressed. As a result, compared with the case where one hole having the same volume as the total volume of the dense holes 5b and 5a is formed, the rigidity of the land portion provided in the tread portion is sufficiently reduced without reducing the water removal effect. Can be secured.

  Similarly, regarding the hole 5 c, the holes 5 a and 5 b are holes located at relatively close positions in the hole group 5. In this case, when viewed from the relationship between the hole 5c and the hole 5a, as shown in FIG. 2, the hole 5c and the hole 5a are densely packed in a narrow region, and the individual holes 5c and 5a are not easily crushed. For this reason, falling of the holes 5c and 5a can be suppressed. As a result, the rigidity of the land portion provided in the tread portion is sufficiently reduced without deteriorating the water removal effect as compared with the case where one hole having the same volume as the total volume of the dense holes 5c and 5a is formed. Can be secured. Further, in the relationship between the holes 5c and 5b, as shown in FIG. 2, the holes 5c and 5b are densely packed in a narrow region, and the individual holes 5c and 5b are not easily crushed. For this reason, falling of the holes 5c and 5b can be suppressed. As a result, the rigidity of the land portion provided in the tread portion is sufficiently reduced without deteriorating the water removal effect as compared with the case where one hole having the same volume as the total volume of the dense holes 5c and 5b is formed. Can be secured.

  In this way, the collapse suppression unit (the unit made up of the hole 5a and the hole 5b, the unit made up of the hole 5b and the hole 5c, and the unit made up of the hole 5c and the hole 5a) constituted by the holes 5a to 5c being densely packed is provided. When each of the holes 5a, 5b, and 5c is used as a reference, at least one exists in a narrow region around each hole including each hole. In other words, in the example shown in FIG. 1, with respect to the hole group 5, there are two collapse-suppressing units around each hole. As a result, in each collapse suppression unit in the hole group 5, the holes 5a to 5c are suppressed from being deformed and crushed.

  Similarly, each of the collapse-inhibiting units (the unit composed of the hole 6a and the hole 6b, the unit composed of the hole 6b and the hole 6c, and the unit composed of the hole 6c and the hole 6a) constituted by the holes 6a to 6c being densely packed. When the holes 6a, 6b, and 6c are used as a reference, there is at least one in a narrow region around each hole including the holes. That is, in the example shown in FIG. 1, regarding the hole group 6, there are two collapse suppression units around each hole. As a result, in each collapse suppression unit in the hole group 6, the holes 6a to 6c are suppressed from being deformed and crushed.

  As described above, in the pneumatic tire of the first embodiment, the hole group 5 (holes 5a to 5c) has the first requirement, and the hole group 6 (holes 6a to 6c) has the first requirement. .

  Next, in the pneumatic tire shown in FIG. 1, at least one hole k belongs to a hole group different from the hole k, and the shortest distance from the hole k is 1.5 mm to 10.0 mm. There is at least one l. When the hole k is the hole 5b and the hole l is the hole 6a, at least one hole 5b in the hole group 5 belongs to a hole group 6 different from the hole 5b as shown in FIG. There is a hole 6a having a shortest distance L to the hole 5b of 1.5 mm to 10.0 mm, which satisfies the second requirement. The shortest distance L is the shortest distance between two notable holes (for example, the hole 5b and the hole 6a in FIG. 5).

  By setting the shortest distance L between the hole 5b and the hole 6a to 1.5 mm or more, the distance between the hole groups 5 and 6 can be sufficiently secured. For this reason, it can suppress that the rigidity of the land part provided in the tread part falls locally. By setting the shortest distance L to 3.0 mm or more, the distance between the hole groups 5 and 6 can be further secured, and the local decrease in the rigidity of the land portion can be further suppressed. In addition, by setting the shortest distance L to 10.0 mm or less, a sufficient number of hole groups can be disposed in the land portion provided in the tread portion, and the water removal effect can be sufficiently ensured. By setting the shortest distance L to 8.0 mm or less, a large number of hole groups can be arranged in the land, and a high water removal effect can be ensured.

  As described above, in the pneumatic tire according to the first embodiment, at least one hole is present at a relatively close position for all the holes 5a, 5b, and 5c (holes 6a, 6b, and 6c) (first requirement). And at least one hole 5b that belongs to the hole group 6 different from the hole 5b and that has the shortest distance L to the hole 5b from 1.5 mm to 10.0 mm exists. (Second requirement) is satisfied. For this reason, when the first requirement and the second requirement are combined to form one hole having the same volume as the plurality of holes 5a to 5c (holes 6a to 6c) densely packed in the hole group 5 (hole group 6) Compared to the case where a single hole having the same volume as all the holes 5a, 5b, 5c, 6a, 6b, 6c included in the plurality of hole groups 5, 6 arranged at a predetermined interval is formed as well as the case of comparison. However, the rigidity of the land portion provided in the tread portion can be sufficiently ensured without reducing the water removal effect. Therefore, according to this pneumatic tire, both on-ice performance and dry performance can be achieved.

  Here, the on-ice performance refers to various performances of the tire on the ice, and particularly means the driving performance and braking performance on the polished ice burn. The dry performance refers to various performances of the tire on the dry road surface, and particularly means driving performance and braking performance on the dry road surface.

  In addition, although the example shown in FIG. 5 is the arrangement | positioning aspect of the hole from which the figure which tied the center of each hole 5a, 5b, 5c becomes a regular triangle, this embodiment is not restricted to this. The hole arrangement modes shown in FIGS. 3-1 to 3-3 also satisfy the first requirement and the second requirement. When all the hole groups shown in FIG. 1 are replaced with the hole group 5 shown in FIG. 3A, for all the holes, at least one hole satisfying dij ≦ (ri + rj) × 2 is present in the hole group to which the hole belongs. (For the hole 5a, the hole 5c, for the hole 5b, the hole 5c, for the hole 5c, the holes 5a, 5b) are present (having the first requirement). Further, at least one hole belongs to a hole group different from the hole, and at least one other hole whose shortest distance from the hole is 1.5 mm to 10.0 mm (for example, for the hole 5b). , Holes 5a) in adjacent hole groups are present (having second requirement).

  In addition, when all the hole groups shown in FIG. 1 are replaced with the hole group 5 shown in FIG. 3B, for all the holes, holes satisfying dij ≦ (ri + rj) × 2 are included in the hole groups to which the holes belong. There is at least one (the hole 5b for the hole 5a, the holes 5a and 5c for the hole 5b, and the hole 5b for the hole 5c) (having the first requirement). Further, at least one hole belongs to a hole group different from the hole, and at least one other hole whose shortest distance from the hole is 1.5 mm to 10.0 mm (for example, for the hole 5c). , Holes 5a) in adjacent hole groups are present (having second requirement).

  Further, when all the hole groups shown in FIG. 1 are replaced with the hole group 5 shown in FIG. 3-3, for all the holes, holes satisfying dj ≦ (ri + rj) × 2 are included in the hole groups to which the holes belong. There is at least one (hole 5b for hole 5a, holes 5a and 5c for hole 5b, holes 5b and 5d for hole 5c, and hole 5c for hole 5d) (having the first requirement). Further, at least one hole belongs to a hole group different from the hole, and at least one other hole whose shortest distance from the hole is 1.5 mm to 10.0 mm (for example, for the hole 5d). , Holes 5a) in adjacent hole groups are present (having second requirement).

  For this reason, also about the example shown to FIGS. 3-1 to 3-3, the high water removal effect and the high rigidity of a tread land part can be acquired, As a result, both on-ice performance and dry performance are fully compatible. can do.

  In the pneumatic tire of the first embodiment, as described above, the shape of the holes constituting the hole groups 5 and 6 is a circle or an n-gon (n ≧ 3) indicated by a solid line in FIGS. Alternatively, it may be a star shape, a saddle shape, an elliptical shape, or the like shown in FIGS. 4-5 to 4-7. Of these, a circular shape or a substantially circular shape is preferable. By making the shape of each hole circular or substantially circular, the water removal effect can be more evenly exhibited in both the tire circumferential direction and the tire width direction, and the rigidity of the tread land portion can be more evenly secured. Therefore, on-ice performance and dry performance can be further enhanced.

  Moreover, in the pneumatic tire of Embodiment 1, as described above, the dimensions and shapes of the holes constituting the hole groups 5 and 6 are made equal for all the holes as shown in FIGS. 3-1 to 3-3. Or at least partly different, but it is preferable that all holes have the same size and shape. By making the size and shape of all the holes equal, when viewed as a whole of the hole groups 5 and 6, the water removal effect can be more evenly exhibited in both the tire circumferential direction and the tire width direction, and the tread land portion Therefore, the on-ice performance and the dry performance can be further enhanced.

  Further, in the pneumatic tire of the first embodiment, the distance between the centers of the holes constituting the hole groups 5 and 6 can be made equal for all the holes as shown in FIG. 1, or from FIG. As shown in 3-3, at least some of the holes may be different, but it is preferable that the distances between the centers of all the holes are equal. By making the distance between the centers of all the holes equal, the hole groups 5 and 6 as a whole can exhibit a water removal effect more evenly in both the tire circumferential direction and the tire width direction, and the tread land The rigidity of the part can be ensured more evenly, and the on-ice performance and the dry performance can be further enhanced.

  In the pneumatic tire of the first embodiment, it is preferable that (ri + rj) × 1.1 ≦ dij ≦ (ri + rj) × 1.9 in the first requirement. By setting (ri + rj) × 1.1 ≦ dij, it is possible to sufficiently secure the interval between the hole i and the hole j and sufficiently secure the rigidity of the land portion existing between these holes. In addition, by setting dj ≦ (ri + rj) × 1.9, the holes i and j are further densely packed in a narrow region so that the individual holes i and j are more difficult to collapse, and the holes i and j are collapsed. Can be suppressed. As a result, the distance between the holes is significantly shortened, compared with the case where one hole having the same volume as the total volume of the plurality of holes is formed, and the land provided in the tread portion is reduced without reducing the water removal effect. The rigidity of the part can be sufficiently secured. When the distance between the centers of the circumscribed circles of the hole i and the hole j is 0, the holes substantially coincide with each other, which is contrary to the technical idea of the first embodiment. Let 0 <dij. Thus, when the said 1st requirement is further limited, the water removal effect and the rigidity of a tread land part can further be improved, and also on-ice performance and dry performance can be improved further.

  In the pneumatic tire of the first embodiment, it is preferable that the volume of at least one hole is different from the volume of other holes in at least one hole group. For example, by adjusting the volume of the holes 5a to 5c for the hole group 5, it is possible to adjust the balance between the rigidity of the land around the holes 5a to 5c and the water removal effect by the holes 5a to 5c. it can. When the volume of each of the holes 5a to 5c is increased, a high water removal effect is obtained, but the land portion rigidity around the holes 5a to 5c is reduced. On the other hand, when the volume of each hole 5a-5c is made small, the water removal effect will be low, but the land part rigidity around it will improve. The volume of each hole 5a-5c can be set by varying the area of the opening part of each hole 5a-5c and the tire radial direction length of each hole 5a-5c. Moreover, the volume of each hole 5a-5c can also be set by varying the three-dimensional shape.

  Moreover, in the pneumatic tire of Embodiment 1, it is preferable that the total volume of the hole groups is different from the total volume of the other hole groups even between the hole groups. For example, by adjusting the total volume of the hole group 5 and the hole group 6, the balance between the land portion rigidity around the hole group 5 and the hole group 6 and the water removal effect by the hole groups 5 and 6 is adjusted. be able to. When the volume of each hole group 5 and 6 is increased, a high water removal effect is obtained, but the land portion rigidity around the hole group is reduced. On the other hand, when the volume of each of the hole groups 5 and 6 is reduced, the water removal effect is low, but the rigidity of the land portion around it is improved.

  In the pneumatic tire of the first embodiment, the radius of the circumscribed circle of all the holes 5a, 5b, 5c (holes 6a, 6b, 6c) in the hole group 5 (hole group 6) is 0.2 mm or more and 1 It is preferable that it is 0.0 mm or less. By making the circumscribed circle radius of all the holes 5a, 5b, 5c (holes 6a, 6b, 6c) 0.2 mm or more, each hole 5a, 5b, 5c (each hole 6a, 6b, 6c) is crushed. Can be sufficiently suppressed, and a water removal effect can be obtained. Moreover, by making the said radius 1.0 mm or less, it can fully suppress that each hole 5a, 5b, 5c (each hole 6a, 6b, 6c) deform | transforms, and can suppress the fall of rigidity. As a result, compared with the case where one hole having the same volume as the total volume of all the holes included in the hole group is formed, the water removal effect and the rigidity of the tread land portion are further improved, and thus the performance on ice and the dry performance. And can be further enhanced.

In the pneumatic tire of the first embodiment, the total volume of the holes 5a, 5b, 5c (holes 6a, 6b, 6c) in the hole group 5 (hole group 6) is preferably 10 mm ³ or less. As a result of setting the total volume of the holes 5a, 5b, 5c (holes 6a, 6b, 6c) to 10 mm ³ or less, a large number of holes having a small volume can be provided. For this reason, it can further suppress that each hole 5a, 5b, 5c (each hole 6a, 6b, 6c) deform | transforms and crushes, and further improves the water removal effect and the rigidity of a tread land part, and by extension, on ice Performance and dry performance can be further enhanced.

[Embodiment 2]
Next, the second embodiment will be described in detail. The second embodiment is different from the first embodiment in that for every hole i in the hole group, at least two holes j satisfying dij ≦ (ri + rj) × 2 exist in the hole group to which the hole belongs.

  FIG. 6 is a plan view illustrating a main part of an example of a tread portion of the pneumatic tire according to the second embodiment. Hereinafter, only the difference between the example (embodiment 2) shown in FIG. 6 and the example (embodiment 1) shown in FIG. 1 will be described in detail. Note that among the elements denoted by the reference numerals in FIG. 6, the elements denoted by the same reference numerals in FIG. 1 indicate the same elements as the elements illustrated in FIG.

  In the example shown in FIG. 6, the block land portion 4 has a plurality of hole groups. In the present embodiment, three hole groups are formed in the tire circumferential direction, and three hole groups are also formed in the tire width direction, and a total of nine hole groups are formed in one block land portion 4. Has been. For example, taking the adjacent hole groups 7 and 8 shown in FIG. 6 as an example, the hole group 7 (hole group 8) includes four holes 7a, 7b, 7c, and 7d (holes 8a, 8b, 8c, 8d). Moreover, the hole group 7 (hole group 8) has an arrangement shape that becomes a square when the centers of the holes 7a to 7d (holes 8a to 8d) are connected.

  FIG. 7 is an enlarged perspective view of the hole group shown in FIG. As shown in FIG. 7, the holes 7a, 7b, 7c and 7d (holes 8a, 8b, 8c and 8d) constituting the hole group 7 (hole group 8) are all cylindrical in the tire radial direction outside. Yes, the inner side in the tire radial direction is tapered. Moreover, each hole 7a-7d (each hole 8a-8d) is bottomed inside the tire radial direction while opening to the tread surface. In addition, since each hole 7a-7d (each hole 8a-8d) is a taper shape in which a hole diameter becomes small gradually in the bottom part, it is suitable for improving the rigidity of a bottom part.

  In the example shown in FIG. 7, the holes 7a, 7b, 7c, 7d (respective holes 8a, 8b, 8c, 8d) have the same tire radial depth. The depth of each hole 7a-7d (each hole 8a-8d) is preferably 2 mm or more in order to obtain a sufficient water removal effect. Further, the depth of each hole 7a to 7d (each hole 8a to 8d) is set to be equal to or less than the depth of the circumferential groove 2 because excellent durability is obtained when the hole bottom does not approach the belt layer. preferable.

  In the example shown in FIG. 6, the arrangement mode of the holes 7a, 7b, 7c, and 7d (holes 8a, 8b, 8c, and 8d) is a square in plan view, but the second embodiment is limited to such a configuration. Absent. FIGS. 8-1 and FIGS. 8-2 are top views which show the variation about the arrangement | positioning aspect of the hole which comprises the hole group formed in the tread part of the pneumatic tire which concerns on Embodiment 2. FIGS. 8A and 8B, for convenience, the holes corresponding to the holes 7a to 7d among the holes 7a to 7d (holes 8a to 8d) illustrated in FIG. 6 are illustrated. However, in this embodiment, FIG. The holes corresponding to the holes 8a to 8d can have the same shape as the holes shown in FIGS.

  As shown in FIG. 6, the holes 7 a, 7 b, 7 c, and 7 d can be arranged in such a manner that the figure connecting the centers of the holes 7 a to 7 d becomes a square, as shown in FIG. In this way, the hole group 7 may be composed of five holes 7a, 7b, 7c, 7d, and 7e, and the figure connecting the centers of the holes 7a to 7e may be a pentagon. As shown in -2, it is also possible to adopt a mode in which a figure composed of five holes 7a to 7e and connecting the centers of the holes 7a to 7e becomes a trapezoid. In the example shown in FIGS. 8A and 8B, the holes 7a to 7e can have the same depth in the tire radial direction.

  On the premise of such an arrangement mode of holes, the hole groups 7 and 8 further satisfy the first requirement and the second requirement described above. FIG. 9 is an enlarged plan view of the hole groups 7 and 8 shown in FIG. As shown in FIG. 9, since the holes 7a, 7b, 7c, and 7d (holes 8a, 8b, 8c, and 8d) are all circular in a plan view, these circumscribed circles are formed as holes 7a to 7d (holes 8a). ˜8d). Here, the radius of the circumscribed circle Ca of the hole 7a is ra, the radius of the circumscribed circle Cb of the hole 7b is rb, the radius of the circumscribed circle Cc of the hole 7c is rc, the radius of the circumscribed circle Cd of the hole 7d is rd, and the circumscribed circle The distance between the centers of the circles Ca and Cc is dac, the distance between the centers of the circumscribed circles Ca and Cd is dad, the distance between the centers of the circumscribed circles Cb and Cc is dbc, and the distance between the centers of the circumscribed circles Cb and Cd is dbd. Further, the radius of the circumscribed circle Ca ′ of the hole 8a is ra ′, the radius of the circumscribed circle Cb ′ of the hole 8b is rb ′, the radius of the circumscribed circle Cc ′ of the hole 8c is rc ′, and the circumscribed circle Cd ′ of the hole 8d is The radius is rd ', the distance between the centers of the circumscribed circles Ca' and Cc 'is dac', the distance between the centers of the circumscribed circles Ca 'and Cd' is dad ', and the distance between the centers of the circumscribed circles Cb' and Cc 'is dbc'. And the distance between the centers of the circumscribed circles Cb ′ and Cd ′ is dbd ′.

  When the hole i is the hole 7a and the hole j is the holes 7c and 7d, as shown in FIG. 9, regarding the hole 7a, dac ≦ (ra + rc) × 2 in relation to the hole 7c and the hole 7d. There is a hole 7c that fills and a hole 7d that satisfies dad ≦ (ra + rd) × 2. When the hole i is the hole 7b and the hole j is the hole 7c and the hole 7d, the hole 7b similarly satisfies dbc ≦ (rb + rc) × 2 in the relationship between the hole 7c and the hole 7d. A hole 7c and a hole 7d satisfying dbd ≦ (rb + rd) × 2 exist. Further, when the hole i is the hole 7c and the hole j is the hole 7a and the hole 7b, similarly, the hole 7c satisfies dac ≦ (ra + rc) × 2 in relation to the hole 7a and the hole 7b. The hole 7a and the hole 7b satisfying dbc ≦ (rb + rc) × 2 exist. In addition, when the hole i is the hole 7d and the hole j is the hole 7a and the hole 7b, similarly, regarding the hole 7d, in relation to the hole 7a and the hole 7b, dad ≦ (ra + rd) × 2 is satisfied. There is a hole 7a that fills and a hole 7b that satisfies dbd ≦ (rb + rd) × 2.

  Similarly, when the hole i is the hole 8a and the hole j is the holes 8c and 8d, as shown in FIG. 9, with respect to the hole 8a, dac ′ ≦ (ra There is a hole 8c satisfying '+ rc') × 2 and a hole 8d satisfying dad ′ ≦ (ra ′ + rd ′) × 2. When the hole i is the hole 8b and the hole j is the hole 8c and the hole 8d, the hole 8b is similarly dbc ′ ≦ (rb ′ + rc ′) in relation to the hole 8c and the hole 8d. There is a hole 8c that satisfies × 2, and a hole 8d that satisfies dbd ′ ≦ (rb ′ + rd ′) × 2. Further, when the hole i is the hole 8c and the hole j is the hole 8a and the hole 8b, similarly, regarding the hole 8c, dac ′ ≦ (ra ′ + rc ′) in relation to the hole 8a and the hole 8b. There is a hole 8a satisfying × 2 and a hole 8b satisfying dbc ′ ≦ (rb ′ + rc ′) × 2. In addition, when the hole i is the hole 8d and the hole j is the hole 8a and the hole 8b, similarly, regarding the hole 8d, dad ′ ≦ (ra ′ + rd ′) in relation to the hole 8a and the hole 8b. ) × 2 and a hole 8b that satisfies dbd ′ ≦ (rb ′ + rd ′) × 2.

  In a pneumatic tire having a tread surface in which such hole groups 7 and 8 are formed, all the holes, in the example shown in FIG. 6, holes 7a, 7b, 7c, 7d, 8a, 8b, 8c, 8d. Has at least one hole at a relatively close position in the hole groups 7 and 8 and has the first requirement.

  As for the hole 7 a, the holes 7 c and 7 d are holes located at relatively close positions in the hole group 7. In this case, as seen from the relationship between the holes 7a and 7c, as shown in FIG. 7, the holes 7a and 7c are densely packed in a narrow region, and the individual holes 7a and 7c are not easily crushed. For this reason, falling of the holes 7a and 7c can be suppressed. As a result, the rigidity of the land portion provided in the tread portion is sufficiently reduced without deteriorating the water removal effect as compared with the case where one hole having the same volume as the total volume of the dense holes 7a and 7c is formed. Can be secured. Further, in view of the relationship between the hole 7a and the hole 7d, as shown in FIG. 7, the hole 7a and the hole 7d are densely packed in a narrow region, and the individual holes 7a and 7d are not easily crushed. For this reason, falling of the holes 7a and 7d can be suppressed. As a result, the rigidity of the land portion provided in the tread portion is sufficiently reduced without deteriorating the water removal effect as compared with the case where one hole having the same volume as the total volume of the dense holes 7a and 7d is formed. Can be secured.

  Similarly, regarding the hole 7 b, the holes 7 c and 7 d are holes located at relatively close positions in the hole group 7. In this case, as seen from the relationship between the hole 7b and the hole 7c, as shown in FIG. 7, the hole 7b and the hole 7c are densely packed in a narrow region, and the individual holes 7b and 7c are not easily crushed. For this reason, falling of the holes 7b and 7c can be suppressed. As a result, the rigidity of the land portion provided in the tread portion is sufficiently reduced without reducing the water removal effect as compared with the case where one hole having the same volume as the total volume of the dense holes 7b and 7c is formed. Can be secured. Further, in view of the relationship between the hole 7b and the hole 7d, as shown in FIG. 7, the hole 7b and the hole 7d are densely packed in a narrow region, and the individual holes 7b and 7d are not easily crushed. For this reason, falling of the holes 7b and 7d can be suppressed. As a result, the rigidity of the land portion provided in the tread portion is sufficiently reduced without reducing the water removal effect as compared with the case where one hole having the same volume as the total volume of the dense holes 7b and 7d is formed. Can be secured.

  Similarly, regarding the hole 7 c, the holes 7 a and 7 b are holes located at relatively close positions in the hole group 7. In this case, as seen from the relationship between the hole 7c and the hole 7a, as shown in FIG. 7, the hole 7c and the hole 7a are densely packed in a narrow region, and the individual hole 7c and the hole 7a are not easily crushed. For this reason, falling of the holes 7c and 7a can be suppressed. As a result, compared with the case where one hole having the same volume as the total volume of the dense holes 7c and 7a is formed, the rigidity of the land portion provided in the tread portion is sufficiently reduced without reducing the water removal effect. Can be secured. Further, in view of the relationship between the hole 7c and the hole 7b, as shown in FIG. 7, the hole 7c and the hole 7b are densely packed in a narrow region, and the individual holes 7c and 7b are not easily crushed. For this reason, falling of the holes 7c and 7b can be suppressed. As a result, the rigidity of the land portion provided in the tread portion is sufficiently reduced without deteriorating the water removal effect as compared with the case where one hole having the same volume as the total volume of the dense holes 7c and 7b is formed. Can be secured.

  Similarly, regarding the hole 7 d, the holes 7 a and 7 b are holes located at relatively close positions in the hole group 7. In this case, as seen from the relationship between the hole 7d and the hole 7a, as shown in FIG. 7, the hole 7d and the hole 7a are densely packed in a narrow region, and the individual holes 7d and 7a are not easily crushed. For this reason, falling of the holes 7d and 7a can be suppressed. As a result, the land portion provided in the tread portion has a sufficient rigidity without deteriorating the water removal effect as compared with the case where one hole having the same volume as the total volume of the dense holes 7d and 7a is formed. Can be secured. Further, in view of the relationship between the hole 7d and the hole 7b, as shown in FIG. 7, the hole 7d and the hole 7b are densely packed in a narrow region, and the individual holes 7d and 7b are not easily crushed. For this reason, falling of the holes 7d and 7b can be suppressed. As a result, compared with the case where one hole having the same volume as the total volume of the dense holes 7d and 7b is formed, the rigidity of the land portion provided in the tread portion is sufficiently reduced without reducing the water removal effect. Can be secured.

  In this way, the fall prevention unit (the unit consisting of the hole 7a and the hole 7c, the unit consisting of the hole 7a and the hole 7d, the unit consisting of the hole 7b and the hole 7c, the hole 7b, which is configured by the holes 7a to 7d being densely packed. And a unit composed of a hole 7d), when each hole 7a, 7b, 7c, 7d is used as a reference, at least one unit exists in a narrow area around the hole including each hole. In other words, in the example shown in FIG. 6, regarding the hole group 7, there are two collapse-suppressing units around each hole. As a result, in each collapse suppression unit in the hole group 7, the holes 7a to 7d are suppressed from being deformed and crushed.

  Similarly, a fall-in suppression unit (a unit composed of a hole 8a and a hole 8c, a unit composed of a hole 8a and a hole 8d, a unit composed of a hole 8b and a hole 8c, a hole 8b and a hole 8a and a hole 8c) In the case where each of the holes 8a, 8b, 8c, and 8d is used as a reference, at least one unit including the holes 8d is present in a narrow area around the hole. In other words, in the example shown in FIG. 6, regarding the hole group 8, there are two collapse-suppressing units around each hole. As a result, in each collapse suppression unit in the hole group 8, the holes 8a to 8d are suppressed from being deformed and crushed.

  As described above, in the pneumatic tire according to the second embodiment, the hole group 7 (holes 7a to 7d) has the first requirement, and the hole group 8 (holes 8a to 8d) has the first requirement. .

  Next, in the pneumatic tire shown in FIG. 6, at least one hole k belongs to a hole group different from the hole k, and the shortest distance from the hole k is 1.5 mm to 10.0 mm. There is at least one other hole l. When the hole k is the hole 7b and the hole l is the hole 8a, at least one hole 7b in the hole group 7 belongs to a hole group 8 different from the hole 7b, as shown in FIG. There is a hole 8a having a shortest distance L to the hole 7b of 1.5 mm to 10.0 mm, which satisfies the second requirement. The shortest distance L is the shortest distance between two notable holes (in FIG. 9, for example, hole 7b and hole 8a).

  By setting the shortest distance L between the hole 7b and the hole 8a to 1.5 mm or more, the distance between the hole groups 7 and 8 can be sufficiently secured. For this reason, it can suppress that the rigidity of the land part provided in the tread part falls locally. By setting the shortest distance L to 3.0 mm or more, the distance between the hole groups 7 and 8 can be further secured, and the local decrease in the rigidity of the land portion can be further suppressed. In addition, by setting the shortest distance L to 10.0 mm or less, a sufficient number of hole groups can be disposed in the land portion provided in the tread portion, and the water removal effect can be sufficiently ensured. By setting the shortest distance L to 8.0 mm or less, a large number of hole groups can be arranged in the land, and a high water removal effect can be ensured.

  As described above, in the pneumatic tire according to the second embodiment, at least one hole exists in a relatively close position for all the holes 7a, 7b, 7c, and 7d (holes 8a, 8b, 8c, and 8d) ( And at least one hole 8b that belongs to the hole group 8 different from the hole 7b and that has the shortest distance L to the hole 7b from 1.5 mm to 10.0 mm is satisfied. Satisfy one (second requirement). Therefore, when these requirements are combined, only when compared with the case where a plurality of holes 7a to 7d (holes 8a to 8d) densely packed in the hole group 7 (hole group 8) are formed and one hole having the same volume is formed. Compared to a case where one hole having the same volume as all the holes 7a, 7b, 7c, 7d, 8a, 8b, 8c, 8d included in the plurality of hole groups 7, 8 arranged at a predetermined interval is formed. However, the rigidity of the land portion provided in the tread portion can be sufficiently ensured without reducing the water removal effect. Therefore, according to this pneumatic tire, both on-ice performance and dry performance can be achieved.

  Furthermore, the example shown in FIG. 9 satisfies the first requirement and the second requirement, and satisfies the following third requirement. That is, the third requirement is that all holes 7a, 7b, 7c, 7d (holes 8a, 8b, 8c, 8d) in the hole group i (7, 8) That is, there are at least two holes j satisfying ≦ (ri + rj) × 2. That is, when the hole i in the third requirement is the hole 7a and the hole j is the hole 7c and the hole 7d, there are two holes 7c and 7d at positions relatively close to the hole 7a. In the case where the hole i in the third requirement is the hole 7b and the hole j is the hole 7c and the hole 7d, the two holes 7c and 7d exist at positions relatively close to the hole 7b. When the hole i in the third requirement is the hole 7c and the hole j is the hole 7a and the hole 7b, the hole 7c has two holes 7a and 7b at relatively close positions. When the hole i in the third requirement is the hole 7d and the hole j is the hole 7a and the hole 7b, the hole 7d has two holes 7a and 7b at relatively close positions. The relationship between the holes 7a to 7d can be used for the holes 8a to 8d.

  As described above, in the pneumatic tire according to the second embodiment, at least one hole exists in a relatively close position for all the holes 7a, 7b, 7c, and 7d (holes 8a, 8b, 8c, and 8d) ( The first requirement) and at least one hole 8b that belongs to the hole group 8 different from the hole 7b and has the shortest distance L to the hole 7b from 1.5 mm to 10.0 mm. Existence (second requirement) and at least two holes in relatively close positions for all holes 7a, 7b, 7c, 7d (holes 8a, 8b, 8c, 8d) (third requirement) In combination with the above, especially in the vicinity of all the holes 7a to 7d (holes 8a to 8d), it is extremely remarkably suppressed that the self or other holes are deformed and crushed. Thereby, the water removal effect and the rigidity of the tread land portion can be further enhanced, and as a result, the on-ice performance and the dry performance can be further enhanced.

  The example shown in FIG. 9 is an arrangement mode of holes in which the figure connecting the center lines of the holes 7a, 7b, 7c, and 7d (respective holes 8a, 8b, 8c, and 8d) is a square. The form is not limited to this. That is, also about the arrangement | positioning aspect of the hole shown to FIGS. 8-1 and FIGS. 8-2, said 1st requirement, 2nd requirement, and 3rd requirement are satisfy | filled. When all the hole groups shown in FIG. 6 are replaced with the hole group 7 shown in FIG. 8A, at least one hole satisfying dij ≦ (ri + rj) × 2 is present in the hole group to which the hole belongs. (E.g., hole 7c, hole 7d for hole 7a) (having the first requirement). Further, at least one hole belongs to a hole group different from the hole, and at least one other hole having a shortest distance from the hole of 1.5 mm to 10.0 mm (for example, for the hole 7b). Exists in the adjacent hole group (having the second requirement). Further, at least two holes (for example, the holes 7c and 7d for the hole 7a) are present at positions relatively close to each other (having the third requirement).

  Further, when all the hole groups shown in FIG. 6 are replaced with the hole group 7 shown in FIG. 8B, for all the holes, holes satisfying dij ≦ (ri + rj) × 2 are included in the hole groups to which the holes belong. There is at least one (for example, hole 7c, hole 7d for hole 7a) (having the first requirement). In addition, at least one hole belongs to a hole group different from the hole and the shortest distance from the hole is 1.5 mm to 10.0 mm (for example, for the hole 7e). Exists in the adjacent hole group (having the second requirement). Further, at least two holes (for example, the holes 7c and 7d for the hole 7a) are present at positions relatively close to each other (having the third requirement).

  For this reason, also about the example shown to FIGS. 8-1 and 8-2, since the high water removal effect and the high rigidity of a tread land part can be acquired, both on-ice performance and dry performance are fully compatible. Can do.

[Embodiment 3]
Subsequently, Embodiment 3 will be described in detail. The third embodiment is different from the first embodiment in that a plurality of sipes are formed in a land portion provided in a tread portion, and a hole group is formed in a small block divided by the sipes.

  FIG. 10 is a plan view illustrating a main part of an example of the tread portion 1 of the pneumatic tire according to the third embodiment. Hereinafter, only the difference between the example shown in FIG. 10 and the example shown in FIG. 1 will be described in detail. Note that among the elements denoted by the reference numerals in FIG. 10, the elements denoted by the same reference numerals in FIG. 1 indicate the same elements as the elements illustrated in FIG. 1.

  In the example shown in FIG. 10, a plurality of sipes extending across the tire circumferential direction are arranged in the block land portion 4, and thereby the block land portion 4 is divided into a plurality of small blocks. In the figure, two sipes 9 are arranged on the block land portion 4, and the block land portion 4 is divided into three small blocks 10.

  The sipe 9 can be formed into a wave shape as shown in FIG. 10 as well as a linear shape or a three-dimensional shape.

  Each of the small blocks 10 divided and formed in this way is formed with three hole groups in the tire width direction, and one block land portion 4 is formed with nine hole groups in total. For example, each of the hole groups 5 and 6 includes three holes 5a, 5b, and 5c (holes 6a, 6b, and 6c) that are circular in a plan view.

  In the pneumatic tire in which the tread surface having such a configuration is formed, as in the pneumatic tire of the first embodiment, all the holes 5a, 5b, and 5c (holes 6a, 6b, and 6c) are relatively close to each other. At least one hole (for example, holes 5b and 5c for the hole 5a) (having the first requirement), and at least one hole 5b belongs to the hole group 6 different from the hole 5b, and There is at least one other hole 6a having the shortest distance L to the hole 5b of 1.5 mm to 10.0 mm (having the second requirement). For this reason, only when compared with the case where these requirements are combined and one hole having the same volume as the plurality of holes 5a to 5c (holes 6a to 6c) densely packed in the hole group 5 (hole group 6) is formed. Rather than the case where one hole having the same volume as all the holes 5a, 5b, 5c, 6a, 6b, and 6c included in the plurality of hole groups 5 and 6 arranged at a predetermined interval is formed. The rigidity of the land portion provided in the tread portion can be sufficiently ensured without reducing the water effect. Therefore, according to this pneumatic tire, both on-ice performance and dry performance can be achieved.

  Furthermore, the pneumatic tire shown in FIG. 10 satisfies the following fourth requirement. In other words, the fourth requirement is that the block land portion 4 is provided with two sipes 9 extending so as to intersect the tire circumferential direction. For this reason, in the example shown in FIG. 10, the water removal effect (1st requirement and 2nd requirement) by the hole groups 5 and 6 and the water removal effect (4th requirement) by the sipe 9 provided in the tread part 1 are included. In combination, a particularly high water removal effect is obtained. Therefore, according to the pneumatic tire of the third embodiment, extremely high performance on ice can be exhibited. In addition, although the example shown in FIG. 10 is an example in which a land part is a block shape, Embodiment 3 is not restricted to such a form, In the case where a land part is a rib-shaped land part, ie, two adjacent. This includes the case where the lateral groove 3 communicating with the circumferential groove 2 is not provided.

[Embodiment 4]
In addition, Embodiment 4 will be described in detail. In the fourth embodiment, a plurality of sipes are formed in the block land portion provided in the tread portion, and the arrangement region of the hole group is an area on the stepping side when the tire rotates on the block land portion, and on the kicking side. It differs from the first and third embodiments in that it is at least one of the regions.

  FIG. 11 is a plan view illustrating a main part of an example of the tread portion 1 of the pneumatic tire according to the fourth embodiment. In the following, only the difference between the example shown in FIG. 11 and the example shown in FIGS. 1 and 10 will be described in detail. 11, the elements denoted by the same reference numerals in FIGS. 1 and 10 are the same elements as those illustrated in FIGS. 1 and 10.

  In the example shown in FIG. 11, a plurality of sipes extending across the tire circumferential direction are arranged in the block land portion 4, and thereby the block land portion 4 is divided into a plurality of small blocks. In the figure, the block land portion 4 is provided with three sipes 9 extending so as to intersect with the tire circumferential direction, whereby the block land portion 4 is divided into four small blocks 10.

  Furthermore, in the example shown in FIG. 11, the hole group is formed in at least one of the stepping side region and the kicking side region during tire rotation in the divided small block 10. Here, the area on the stepping side when the tire rotates is an area that first contacts the ground when the tire is rotating in the forward direction. In FIG. Upper end region or lower end region). On the other hand, the area on the kick-out side when the tire rotates is an area that comes into contact with the ground last when the tire rotates in the forward direction, and is the other end area in the tire circumferential direction of the block land portion 4 in FIG. (Lower end area or upper end area of the paper). Further, the forward rotation of the tire means tire rotation when the vehicle body equipped with the tire moves forward.

  In the pneumatic tire in which the tread surface having such a configuration is formed, all the holes 5a, 5b, and 5c (holes 6a, 6b, and 6c) are compared in the same manner as the pneumatic tires of the first and third embodiments. There is at least one hole at a position close to the target (having the first requirement), and at least one hole 5b belongs to a hole group 6 different from the hole 5b, and the shortest distance L to the hole 5b is There is at least one other hole 6a that is 1.5 mm to 10.0 mm (having the second requirement). Further, three sipes 9 extending across the tire circumferential direction are disposed on the block land portion 4 (having the fourth requirement). For this reason, the water removal effect (1st requirement and 2nd requirement) by the hole groups 5 and 6 and the water removal effect (4th requirement) by the sipe 9 provided in the tread part 1 are combined, and particularly high water removal An effect is obtained. Therefore, according to the pneumatic tire of the fourth embodiment, extremely high performance on ice can be exhibited.

  Furthermore, the pneumatic tire of Embodiment 4 shown in FIG. 11 satisfies the following fifth requirement. That is, the fifth requirement is that the hole groups 5 and 6 are formed in at least one of a stepping side region and a kicking side region during tire rotation in the divided small blocks 10. . In the example shown in the figure, the hole groups 5 and 6 are formed in the stepping side region when the tire rotates. Thereby, the water absorption effect at the time of tire rotation increases, As a result, on-ice performance can further be improved. In particular, in the example shown in the figure, when the tire rotates in the forward direction, since the hole groups 5 and 6 are formed in the region where the tire first contacts the ground, the water absorption effect is effectively exhibited during the tire forward rotation.

  The example shown in FIG. 11 is an example in which the hole groups 5 and 6 are formed in only one region on the stepping side or the kicking side when the tire rotates, but the fourth embodiment is not limited to such a form. In addition, a configuration in which the hole groups 5 and 6 are formed in both the stepping side region and the kicking side region during tire rotation is also included. In addition, when the hole groups 5 and 6 are formed in the stepping side region at the time of tire rotation, as described above, the water absorption effect at the time of forward rotation of the tire is increased, and as a result, the performance on ice is further improved. . On the other hand, when the hole groups 5 and 6 are formed in the area on the kick-out side when the tire rotates, the water absorption effect when the tire rotates in the reverse direction is increased, and as a result, the performance on ice is further improved. Here, the reverse rotation of the tire means tire rotation when the vehicle body equipped with the tire moves backward.

  As shown in FIG. 11, the area on the stepping-in side and the area on the kicking-out side of the block land portion 4 when the tire rotates are blocked from one end (the upper end of the paper surface) or the other end (the lower end of the paper surface) of the block land portion 4. It is preferable to set the area up to 30% or less of the tire circumferential direction length W of the land portion 4. By disposing the hole groups 5 and 6 in such an area, the water absorption effect at the time of tire rotation is sufficiently increased, and as a result, the performance on ice is remarkably improved.

  Pneumatic tires according to this embodiment and conventional examples were manufactured and evaluated. The embodiment according to the present embodiment is an example.

[Example Group 1]
In the pneumatic tire having a common tire size of 195 / 65R15, various items shown in FIG. 12 (block tread pattern, number of holes in the hole group, total volume of holes, shortest distance between the hole groups, and 1 Each of the pneumatic tires of Examples 1 to 3 provided with each hole group satisfying the volume of one hole on the entire circumference of the tire was manufactured. Also, in the tread pattern of the block land portion of FIG. 12, the pneumatic tires of Conventional Examples 1 and 2 in which one hole is provided at three or nine locations (for the other structures, the pneumatic tires of Examples 1 to 3 and The same) was produced respectively. In addition, all the holes i included in all the hole groups of the pneumatic tires of Examples 1 to 3 have at least one hole j satisfying dij ≦ (ri + rj) × 2 among the hole groups to which the pneumatic tire belongs. To do.

  Each of these test tires was mounted on a rim having a rim size of 15 × 6 JJ, the air pressure was set to 230 kPa, and an evaluation test was performed on ice performance and dry performance under the following measurement conditions. The vehicle used was a 1500cc class (Corolla Axio) general passenger car.

  Regarding the performance on ice, the braking stop distance from the initial speed of 40 km / h was measured in a polished ice burn (on the ice surface). As for dry performance, the braking stop distance from the initial speed of 100 km / h was measured on the dry road surface.

  About these performance, all were computed as a relative index | exponent which set the pneumatic tire which concerns on the prior art example 1 to 100. About these indexes, it means that each performance is excellent, so that it is large. The above evaluation results are also shown in FIG.

  As can be seen from FIG. 12, for the pneumatic tires of Examples 1 to 3 within the scope of the present invention, excellent results exceeding 100 were obtained for any of the evaluation items on ice performance and dry performance. Yes. This is because in the pneumatic tires of Examples 1 to 3, at least one hole j satisfying dij ≦ (ri + rj) × 2 exists in the hole group to which all the holes i belong, and at least 1 This is probably because there is at least one hole l that belongs to a hole group different from the hole k and has the shortest distance from the hole k of 1.5 mm to 10.0 mm.

  Looking at Examples 1 to 3 individually, the pneumatic tire of Example 2 is superior to the pneumatic tire of Example 1 in terms of dry performance. This is different from the pneumatic tire of Example 1 in the pneumatic tire of Example 2. For all the holes i in the hole group, dij ≦ (ri + rj) × 2 This is considered to be because there are at least two holes j satisfying the above. Moreover, the pneumatic tire of Example 3 was superior to the pneumatic tire according to Example 2 in terms of both on-ice performance and dry performance. This is because, in the pneumatic tire of Example 3, unlike the pneumatic tire of Example 2, the volume of at least one hole is different from the volume of other holes in at least one hole group. Conceivable.

  On the other hand, the dry performance of the pneumatic tire of Conventional Example 2 is lower than that of the pneumatic tire of Conventional Example 1. This is because the pneumatic tire of the conventional example 2 is provided with holes having the same total volume dispersed as compared with the pneumatic tire of the conventional example 1, so that the dry performance is reduced due to the decrease in rigidity of the land portion. It is thought that it decreased.

[Example group 2]
In a pneumatic tire having a common tire size of 195 / 65R15, each hole group satisfying various items shown in FIG. 13 (the tread pattern of the block land portion and the shortest distance between the hole groups) is provided on the entire circumference of the tire. The pneumatic tires of Examples 4 and 5 were manufactured. Moreover, as shown in FIG. 13, the pneumatic tire of the conventional example 3 (it is the same as the pneumatic tire of Examples 4 and 5 about the other structure) of the tread pattern which formed only the sipe in the block land part was manufactured. . In addition, all the holes i included in all the hole groups of the pneumatic tires of Examples 4 and 5 have at least one hole j that satisfies dij ≦ (ri + rj) × 2 in the hole group to which the pneumatic tire belongs. To do.

  Each of these test tires was mounted on a rim having a rim size of 15 × 6 JJ, the air pressure was set to 230 kPa, and evaluation tests on ice performance and dry performance were performed in the same manner as in Example Group 1 under the following measurement conditions. All of these performances were calculated as relative indices with the pneumatic tire according to Conventional Example 3 as 100. About these indexes, it means that each performance is excellent, so that it is large. The above evaluation results are also shown in FIG.

  As can be seen from FIG. 13, for the pneumatic tires of Examples 4 and 5 within the scope of the present invention, excellent results exceeding 100 were obtained for at least one of the evaluation items on ice and dry performance. Yes. This is because in the pneumatic tires of Examples 4 and 5, at least one hole j satisfying dij ≦ (ri + rj) × 2 exists in the hole group to which all the holes i belong, and at least 1 This is probably because there is at least one hole l that belongs to a hole group different from the hole k and has the shortest distance from the hole k of 1.5 mm to 10.0 mm.

  Looking at Examples 4 and 5 individually, the pneumatic tire of Example 5 is superior to the pneumatic tire of Example 4 in terms of performance on ice. This is considered to be because the so-called edge effect of the pneumatic tire of Example 5 was increased by the combined use of the hole group and sipe as compared with the pneumatic tire of Example 4. Further, the dry performance of the pneumatic tire of Example 5 is lower than that of the pneumatic tire of Example 4. This is probably because the pneumatic tire of Example 5 has a lower land rigidity than the pneumatic tire of Example 4 due to the combined use of the hole group and sipe.

  As described above, the pneumatic tire according to the present invention is useful for achieving both on-ice performance and dry performance.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Circumferential groove 3 Horizontal groove 4 Block land part 5, 6, 7, 8 Hole group 5a, 5b, 5c, 5d, 6a, 6b, 6c, 7a, 7b, 7c, 7d, 7e, 8a, 8b, 8c, 8d hole 9 sipe 10 small block L shortest distance W land length in tire circumferential direction

Claims (7)

The tread surface includes at least two holes having three or more holes;
The hole has a bottom on the inner side in the tire radial direction, and has a tapered shape where the hole diameter gradually decreases at the bottom part,
For any two holes i and j in the hole group, in plan view, the radius of the circumscribed circle Ci of the hole i is ri, the radius of the circumscribed circle Cj of the hole j is rj, and both the circumscribed circles Ci, When the distance between the centers of Cj is dj,
For all holes i, there exists at least one hole j satisfying dij ≦ (ri + rj) × 2 in the hole group to which the hole belongs,
At least one hole k belongs to a group of holes different from the hole k, and at least one hole l having a shortest distance from the hole k of 1.5 mm to 10.0 mm exists. Enter tire.   The pneumatic tire according to claim 1, wherein, for all holes i in the hole group, at least two holes j satisfying dij ≦ (ri + rj) × 2 exist in the hole group to which the hole belongs.   The pneumatic tire according to claim 1 or 2, wherein in at least one hole group, the volume of at least one hole is different from the volume of other holes.   The pneumatic tire according to any one of claims 1 to 3, wherein a radius of a circumscribed circle of all the holes in the hole group is 0.2 mm or more and 1.0 mm or less. The pneumatic tire according to any one of claims 1 to 4, wherein the total volume of the holes in the hole group is 10 mm ³ or less.   The pneumatic according to any one of claims 1 to 5, wherein a plurality of sipes are formed in a land portion provided in a tread portion, and the hole group is formed in a small block divided by the sipes. tire.   A plurality of sipes are formed in the block land portion provided in the tread portion, and the arrangement region of the hole group is at least one of a stepping side region and a kicking side region of the block land portion when the tire rotates. The pneumatic tire according to any one of claims 1 to 6.

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