JP6241158B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire with improved braking performance on ice.

  Conventionally, with respect to studless tires, a technique for improving performance on ice (braking performance and driving performance) is known (see, for example, Patent Document 1). The pneumatic tire disclosed in Patent Document 1 has a tread pattern in which a plurality of blocks are densely arranged in a lattice shape.

International Publication No. 2010/032606

  In general, when anisotropy is given to the shape of the block defined by the grooves, only the resistance against an external force in a specific direction is increased, and the specific performance of the tire performance tends to be improved. For example, when anisotropy is given to the shape of the block in the tire circumferential direction to increase the resistance against external force in the tire circumferential direction, the braking performance on ice and the braking performance on snow are improved.

  Moreover, when anisotropy is given to the shape of the groove that defines the block, the drainage performance tends to be improved. For example, when a V-shaped groove in the tire width direction is disposed, the first grounding side (stepping side) of the block defined by the groove is the V-shaped apex, so that water is removed from the groove. It is possible to efficiently drain and improve drainage performance.

  About the pneumatic tire disclosed by patent document 1, the shape of each block does not have anisotropy in any direction. For this reason, it is unclear whether the braking performance on ice, the braking performance on snow, and the drainage performance are exhibited in a balanced manner depending on the pneumatic tire.

  The present invention has been made in view of the above circumstances, and in particular, an object of the present invention is to provide a pneumatic tire in which braking performance on ice, braking performance on snow, and drainage performance are improved in a well-balanced manner. And

  The pneumatic tire according to the present invention has a circumferential main groove, a plurality of circumferential narrow grooves, and a plurality of widthwise narrow grooves that intersect the circumferential narrow grooves, and are adjacent to each other in the tire width direction. This is a pneumatic tire in which small block rows are partitioned. The circumferential narrow grooves are disposed at a tire width direction density of 0.06 / mm or more and 0.2 / mm or less. The narrow groove in the width direction has at least one bent portion. The small block row includes a wide small block and a narrow small block. The bending angle at the bent portion is not less than 40 ° and not more than 160 °.

  In the pneumatic tire according to the present invention, the improvement in the arrangement density of the circumferential narrow grooves in the tire width direction is made, and the small blocks constituting the small block row are provided on the premise that the narrow grooves are provided in the width direction narrow grooves. The shape is improved, and the bending angle of the bent portion is further improved. As a result, according to the pneumatic tire of the present invention, the braking performance on ice, the braking performance on snow, and the drainage performance are improved in a well-balanced manner.

FIG. 1 is a plan view showing a tread portion of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an enlarged plan view showing the periphery of the circled portion of the tread portion shown in FIG. FIG. 3 is a plan view showing a tread portion of the pneumatic tire according to the embodiment of the present invention. 4 is a plan view showing the relationship between small blocks B1 and B2 adjacent in the tire circumferential direction in the pneumatic tire shown in FIG. 1 or FIG. 3, and (a) is a tire circumferential region in which the small blocks are the same. (B) is a case where the small blocks have the same tire circumferential direction region. FIG. 5 is a plan view showing the sipe arrangement in the block B1 shown in FIG. 2, wherein (a) is an example in which the sipe extends in the tire width direction, and (b) is a sipe in the width direction. This is an example extending in parallel with the groove.

  Hereinafter, embodiments of the pneumatic tire according to the present invention (basic modes and additional modes 1 to 7 shown below) will be described in detail with reference to the drawings. Note that these embodiments do not limit the present invention. In addition, the constituent elements of the above embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially the same. Furthermore, various forms included in the above-described embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

<Basic form>
Below, the basic form is demonstrated about the pneumatic tire which concerns on this invention. In the following description, the tire radial direction means a direction orthogonal to the rotational axis of the pneumatic tire, the tire radial inner side is the side toward the rotational axis in the tire radial direction, and the tire radial outer side is in the tire radial direction. The side away from the rotation axis. The tire circumferential direction refers to a circumferential direction with the rotation axis as a central axis. Further, the tire width direction means a direction parallel to the rotation axis, the inner side in the tire width direction means the side toward the tire equatorial plane CL (tire equator line) in the tire width direction, and the outer side in the tire width direction means the tire width direction. Is the side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane that is orthogonal to the rotational axis of the pneumatic tire and passes through the center of the tire width of the pneumatic tire.

[Basic form 1]
The basic form 1 is a form for a pneumatic tire in which the rotation direction is specified. FIG. 1 is a plan view showing a tread portion of a pneumatic tire according to an embodiment of the present invention (a view of a grounded tire viewed from directly above). The pneumatic tire 1 shown in the figure is a tire in which the rotation direction (the tire rolling direction when the vehicle is moving forward) is determined. In the pneumatic tire 1, the stepping side in FIG. 1 is grounded before the kicking side. The tread portion 10 of the pneumatic tire 1 shown in FIG. 1 is made of a rubber material (tread rubber), is exposed at the outermost side in the tire radial direction of the pneumatic tire 1, and the surface thereof is the contour of the pneumatic tire 1. The surface of the tread portion 10 is formed as a tread surface 12 that is a surface that comes into contact with the road surface when a vehicle (not shown) on which the pneumatic tire 1 is mounted travels.

  As shown in FIG. 1, the tread surface 12 has grooves 14 and 18 (for example, grooves 18a and 18b) extending in the tire circumferential direction and grooves 22 (for example, grooves 22a and 18a) that are inclined with respect to the tire circumferential direction. 22b) and the tread pattern shown in FIG. The specific configuration of the grooves 14 to 22 is as follows.

  That is, two circumferential main grooves 14 that are symmetrical with respect to the tire equatorial plane CL are provided on the tread surface 12. Between the two circumferential main grooves 14 and on both outer sides in the tire width direction of each circumferential main groove 14, the width is narrower than the circumferential main groove 14 and extends in the tire circumferential direction. A plurality of circumferential narrow grooves 18 whose width direction dimensions change in the middle of the extension are provided.

  Further, the tread surface 12 is zigzag between the two circumferential main grooves 14 and on both outer sides in the tire width direction of each circumferential main groove 14 and narrower than the circumferential main groove 14 in the tire width direction. A plurality of narrow grooves 22 extending in the width direction are disposed.

  Thus, in the example shown in FIG. 1, a plurality of small block rows adjacent in the tire width direction by the plurality of circumferential narrow grooves 18 and the plurality of width narrow grooves 22 intersecting with the circumferential narrow grooves 18. Is formed. In the present embodiment, there is a circumferential thick groove (circumferential main groove 14 in FIG. 1) that is wider than the circumferential narrow groove 18 and extends substantially in the tire circumferential direction. In this case, the land portion defined between the circumferential grooves is regarded as a rib. Further, in the present embodiment, the widthwise thick groove that is wider than the widthwise narrow groove 22 and extends substantially in the tire width direction in the tire widthwise region in which the widthwise narrow groove 22 is disposed. When there is further (not present in FIG. 1), the land portion defined between the circumferential thick grooves and the land portion defined between the widthwise thick grooves is regarded as a block.

  Moreover, in this Embodiment, the groove width of the circumferential direction main groove 14 can be 4.0 mm or more. Here, the groove width refers to the maximum dimension of the groove in a direction perpendicular to the direction in which the groove extends.

  Under such a premise, in the present embodiment (basic form 1), the circumferential narrow grooves 18 are arranged at a density in the tire width direction of 0.06 / mm or more and 0.2 / mm or less. . Here, the density in the tire width direction of the circumferential narrow grooves 18 means that the circumferential narrow grooves 18 per unit length in the tire width direction in the tire width direction region between the ground contact ends E shown in FIG. It means the number of arrangement.

  Further, in the present embodiment, the width direction narrow groove 22 has at least one bent portion in the example shown in FIG. In other words, in the example shown in FIG. 1, one bent portion is formed between adjacent circumferential narrow grooves 18 (for example, between the circumferential narrow grooves 18 a and 18 b) with respect to one width-direction narrow groove 22.

  Furthermore, in the present embodiment, the small block row includes a wide small block B1 and a narrow small block B2. In the example shown in FIG. 1, a wide block B1 and a narrow block B2 are tires in one small block row formed between adjacent circumferential narrow grooves (for example, circumferential narrow grooves 18a and 18b). They are alternately formed in the circumferential direction.

FIG. 2 is an enlarged plan view showing the periphery of the circled portion of the tread portion shown in FIG. In the present embodiment, as shown in the figure, the bending angle θ at the bent portion of the width direction narrow groove 22 is not less than 40 ° and not more than 160 ° .

(Action etc.)
In the pneumatic tire according to the present embodiment, by arranging the circumferential narrow grooves 18 at a tire width direction density of 0.06 / mm or more, the tire circumference of the wide small block B1 and the narrow small block B2 Any of the lengths in the direction can be suppressed from being excessively reduced with respect to the length in the tire width direction. Thereby, the falling of the wide small block B1 and the narrow small block B2 in the tire circumferential direction is suppressed, and a sufficient resistance against the external force in the tire circumferential direction is ensured, and excellent braking performance on ice and excellent on snow The braking performance can be demonstrated.

  On the other hand, in the pneumatic tire of the present embodiment, the tires of the wide small block B1 and the narrow small block B2 are provided by arranging the circumferential narrow grooves 18 at a tire width direction density of 0.2 / mm or less. A sufficient edge component in the tire width direction can be ensured for the edges extending zigzag in the width direction. As a result, the resistance against the external force in the tire circumferential direction can be increased, and as a result, excellent braking performance on ice and excellent braking performance on snow can be exhibited.

  In addition, the said effect can be show | played by a higher level each by making arrangement | positioning density of the tire width direction of the circumferential direction fine groove 18 0.08 piece / mm or more and 0.12 piece / mm or less.

  Further, in the pneumatic tire of the present embodiment, the shape of the wide small block B1 and the narrow small block B2 defined by the width direction narrow groove 22 by providing at least one bent portion in the width direction narrow groove 22. Further, anisotropy, that is, anisotropy in the tire circumferential direction is given in FIG. As a result, the drag force against the external force in the tire circumferential direction can be increased as compared with the drag force against the external force in the other direction, and as a result, excellent braking performance on ice and excellent braking performance on snow can be exhibited. .

  In this way, by providing at least one bent portion in the width direction narrow groove 22, the first ground side (stepping side) of the wide small block B1 and the narrow small block B2 defined by the width direction narrow groove 22 is formed. ) Can be the vertex of the V-shape. Thereby, water can be efficiently discharged | emitted from the width direction groove | channel 22, and drainage performance can be improved.

  Further, in the pneumatic tire according to the present embodiment, the small block row includes the wide small block B1 and the narrow small block B2, so that the circumferentially narrow block B2 particularly in the tire width direction both outsides. A wide width of the groove 18 can be ensured. As a result, even when the narrow block B2 collapses in the tire width direction, a gap remains on both outer sides in the tire width direction of the narrow block B2, so that sufficient snow column shearing force is ensured and excellent on the snow. Braking performance can be realized. Further, as described above, the gaps remain on both outer sides in the tire width direction of the narrow block B2, so that the resistance against the external force in the tire width direction can be efficiently achieved by the edges on both outer sides in the tire width direction of the narrow block B2. Can be generated. As a result, excellent turning performance on snow can be achieved.

  In addition, in the pneumatic tire of the present embodiment, by setting the bending angle θ at the bent portion to 40 ° or more, the wide small block B1 and the narrow small block B2 defined by the width direction narrow groove 22 The edge component of the tire has a sufficient edge component in the tire width direction. As a result, the resistance against the external force in the tire circumferential direction can be increased, and as a result, excellent braking performance on ice and excellent braking performance on snow can be exhibited. Further, by setting the bending angle θ at the bent portion to 160 ° or less, the edge component in the tire circumferential direction is sufficiently provided at the edges of the wide and small blocks B1 and B2 formed by the widthwise narrow grooves 22. I have it. As a result, it is possible to increase the resistance against the external force in the tire width direction, thereby realizing excellent turning performance on ice and excellent turning performance on snow.

  In addition, the said effect can be show | played by a higher level each by making bending angle (theta) in a bending part into 60 degrees or more and 140 degrees or less.

  As described above, the pneumatic tire according to the present embodiment is small on the premise that the circumferential narrow groove is improved in arrangement density in the tire width direction and a bent portion is provided in the wide narrow groove. The shape of the small blocks constituting the block row is improved, and the bending angle of the bent portion is further improved. As a result, the pneumatic tire according to the present embodiment can improve the braking performance on ice, the braking performance on snow, and the drainage performance in a well-balanced manner.

  In addition, although not shown in figure, the pneumatic tire which concerns on this Embodiment shown above has the same meridional cross-sectional shape as the conventional pneumatic tire. Here, the meridional cross-sectional shape of the pneumatic tire refers to a cross-sectional shape of the pneumatic tire that appears on a plane perpendicular to the tire equatorial plane CL. The pneumatic tire according to the present embodiment has a bead portion, a sidewall portion, a shoulder portion, and a tread portion from the inner side in the tire radial direction toward the outer side in a tire meridian cross-sectional view. And, for example, in the tire meridional section, the pneumatic tire extends from the tread portion to the bead portions on both sides and wound around the pair of bead cores, and on the outer side in the tire radial direction of the carcass layer. A belt layer and a belt reinforcing layer are sequentially formed.

  In addition, the pneumatic tire of the present embodiment includes normal manufacturing processes, that is, a tire material mixing process, a tire material processing process, a green tire molding process, a vulcanization process, and an inspection process after vulcanization. It is obtained through the process. When manufacturing the pneumatic tire according to the present embodiment, in particular, a concave portion and a convex portion corresponding to the tread pattern shown in FIG. 1 are formed on the inner wall of the vulcanizing mold, and this mold is used for the addition. Sulfur is performed.

[Basic form 2]
The basic form 2 is a form for a pneumatic tire whose rotation direction is not specified. FIG. 3 is a plan view showing the tread portion of the pneumatic tire according to the embodiment of the present invention (a view of the grounded tire viewed from directly above). The pneumatic tire 2 shown in the figure has a tread pattern that is point-symmetric with respect to the tire equatorial plane CL. Among the reference numerals shown in the figure, the same reference numerals as those shown in FIG. 1 denote the same components as those shown in FIG.

  The tread portion 11 of the pneumatic tire 2 shown in FIG. 3 is made of a rubber material (tread rubber) similarly to the basic form 1 shown in FIG. 1 and is exposed at the outermost side in the tire radial direction of the pneumatic tire 2. The surface is the contour of the pneumatic tire 2. The surface of the tread portion 11 is formed as a tread surface 13 that is a surface that comes into contact with the road surface when a vehicle (not shown) on which the pneumatic tire 2 is mounted travels.

  Also in the example shown in FIG. 3, a plurality of circumferential narrow grooves 18 (for example, grooves 18 a and 18 b), and a plurality of width-direction narrow grooves 24 (for example, 24 a and 24 b) intersecting with these circumferential narrow grooves 18, Thus, a plurality of small block rows adjacent in the tire width direction are formed.

  Under such a premise, also in the present embodiment (basic form 2), the circumferential narrow grooves 18 are disposed at a tire width direction density of 0.06 / mm or more and 0.2 / mm or less, and the width The direction narrow groove 24 has at least one bent portion as shown in FIG. The small block row includes wide and small blocks B1 and B3 and narrow and small blocks B2 and B4, and the bending angle θ at the bent portion is 40 ° or more and 160 ° or less.

  The wide small block B1 and the wide small block B3 have the same size and opposite directions in the tire circumferential direction. Similarly, the narrow block B2 and the narrow block B4 have the same size and opposite directions in the tire circumferential direction. In the example shown in FIG. 3, the small block rows in which the wide small blocks B1 and the narrow small blocks B2 are alternately formed in the tire circumferential direction, and the wide small blocks B3 and the narrow small blocks B4 are alternately formed in the tire circumferential direction. The small block rows are alternately formed in the tire width direction.

  As described above, in the pneumatic tire according to the basic mode 2, the arrangement density of the circumferential narrow grooves in the tire width direction is improved and the small tires are provided on the premise that the bent portions are provided in the width narrow grooves. The shape of the small blocks constituting the block row is improved, and the bending angle of the bent portion is further improved. As a result, the pneumatic tire according to the present embodiment can improve the braking performance on ice, the braking performance on snow, and the drainage performance in a well-balanced manner.

<Additional form>
Next, additional modes 1 to 7 that can be optionally implemented with respect to the basic mode of the pneumatic tire according to the present invention will be described.

[Additional form 1]
In the basic form (basic forms 1 and 2), the narrow grooves 22 and 24 in the width direction are arranged at a tire circumferential density of 0.04 / mm or more and 0.3 / mm or less in each of FIGS. It is preferable (additional form 1).

  Here, the tire circumferential direction density of the width direction narrow grooves 22 and 24 means the number of the width direction narrow grooves 22 and 24 arranged per unit length in the tire circumferential direction.

  The tire width direction length of each of the small blocks B1, B2, B3, and B4 is arranged in the tire by arranging the width direction narrow grooves 22 and 24 at a circumferential density of 0.04 / mm or more. It is possible to suppress excessively reducing the circumferential length. Thereby, the falling of the small blocks B1 to B4 in the tire width direction can be suppressed, and a sufficient resistance against the external force in the tire width direction can be secured to improve the turning performance on ice and the turning performance on snow. it can.

  On the other hand, by arranging the width direction narrow grooves 22 and 24 at a circumferential density of 0.3 / mm or less, the edge extending in the tire circumferential direction formed in the small blocks B1 to B4 is sufficiently long. can do. As a result, the resistance against the external force in the tire width direction can be increased, and consequently the turning performance on ice and the turning performance on snow can be improved.

[Additional form 2]
In the basic form and the form in which the additional form 1 is added to the basic form, in FIGS. 1 and 3, the tire width direction dimension of the narrow blocks B2 and B4 is 60 of the tire width direction dimension of the wide blocks B1 and B3. % To 90% (additional form 2). Here, the tire width direction dimension of the small blocks B1 to B4 refers to the maximum dimension of the block in the tire width direction.

  The tire width direction dimensions of the narrow blocks B2, B4 are 60% or more of the tire width direction dimensions of the wide blocks B1, B3, respectively, so that both sides of the narrow blocks B2, B4 in the tire width direction (tire width direction) It is possible to further improve the braking performance especially on ice, by ensuring a sufficient land portion rigidity without excessively increasing the groove region on the outer side and the inner side in the tire width direction.

  On the other hand, by setting the tire width direction dimensions of the narrow blocks B2 and B4 to 90% or less of the tire width direction dimensions of the wide blocks B1 and B3, respectively, grooves on both sides of the narrow blocks B2 and B4 in the tire width direction are provided. A sufficient area can be secured. As a result, even when the narrow blocks B2 and B4 fall down in the tire width direction, a gap remains on both outer sides in the tire width direction, so that sufficient snow column shearing force is secured, and braking performance on snow is improved. Further improvements can be made.

[Additional form 3]
In the basic form and the form in which at least one of the additional forms 1 and 2 is added to the basic form, in FIG. 1 (FIG. 3), the narrow block B2 (B4) has a minimum width part of the wide block B1 (B3). ) In the tire width direction center part 50% or more of the tire width direction, and the maximum width part satisfies the area of 90% or less in the tire width direction center part of the wide small block B1 (B3). It is preferable to include 30% or more in the entire tire circumference (additional form 3).

  Here, the center in the tire width direction of the wide and small blocks B1 and B3 is one side of the bent portion in the tire width direction when attention is paid to one wide and small block B1 (B3) as shown in FIG. In the tire width direction region R from the end portion of the tire to the other end portion, a portion that exists symmetrically on both sides in the tire width direction including the center line L with respect to the center line L in the tire width direction.

  In the present embodiment, first, it is defined that a central small block having a predetermined shape is included in the narrow block B2 (B4). The central small block includes a region where the minimum width portion is 50% or more of the tire width direction central portion of the wide small block B1 (B3), and the maximum width portion is the central portion of the wide small block B1 (B3) in the tire width direction. Includes 90% or less area.

  When the minimum width portion of the central small block includes an area of 50% or more of the central portion in the tire width direction of the wide small block B1 (B3), an external force in the tire circumferential direction is applied to the small blocks B1 to B4 so that the wide small block When B1 (B3) and the narrow block B2 (B4) come into contact with each other, the wide block B1 (B3) and the narrow block B2 (B4) can sufficiently support each other. As a result, the collapse of the blocks B1 to B4 in the tire circumferential direction is suppressed, and the braking performance particularly on ice can be further improved.

  On the other hand, the maximum width portion of the central small block includes the region of 90% or less of the center portion in the tire width direction of the wide small block B1 (B3), so that the groove regions are sufficiently provided on both sides in the tire width direction of the central small block. Can be secured. As a result, even when the central small block collapses in the tire width direction due to the external force in the tire width direction, sufficient snow column shear force is ensured by the gap remaining on both outer sides in the tire width direction of the central small block, The braking performance on snow can be further improved.

  As described above, the central small block has only the maximum width portion and the minimum width portion limited, and there are no other restrictions. For this reason, for example, any shape such as a shape in which only the central portion in the tire circumferential direction is narrow or a shape in which only the central portion in the tire circumferential direction is wide can be used.

  And in this Embodiment, about the center small block mentioned above by making the ratio of the center small block which occupies for narrow block B2 and B4 in the tire perimeter of one small block row | line into 30% or more. The improvement effect of braking performance on ice and the improvement effect of braking performance on snow can be achieved at a high level.

[Additional form 4]
In the basic form and the form obtained by adding at least one of the additional forms 1 to 3 to the basic form, the groove width of the circumferential narrow groove 18 is 1.0 mm or more and 10.0 mm or less in each of FIGS. Some (additional form 4) is preferred. Here, the groove width of the circumferential narrow groove 18 refers to a groove dimension measured in a direction perpendicular to the extending direction of the circumferential narrow groove 18.

  By setting the groove width of the circumferential narrow groove 18 to 1.0 mm or more, drainage performance on ice can be further enhanced. In addition, by setting the groove width to 10.0 mm or less, when an external force in the tire width direction is applied, small blocks adjacent to each other in the tire width direction formed by the common circumferential narrow groove 18 (see FIG. In the example shown in FIG. 1, the small blocks B1 are in contact with each other, and in the example shown in FIG. 3, the small blocks B1 and B3) are in contact with each other and support each other. Thereby, falling of the small blocks B1 and B3 in the tire width direction is suppressed, and the turning performance on ice and the turning performance on snow can be further improved.

  In addition, the said effect can be show | played by a higher level each by making the groove width of the circumferential direction fine groove 18 into 2.0 mm or more and 8.0 mm or less.

[Additional form 5]
In the basic form and the form obtained by adding at least one of the additional forms 1 to 4 to the basic form, the groove width of the width direction narrow groove 22 (24) in FIG. It is preferably 0 mm or less (additional form 5). Here, the groove width of the widthwise narrow groove 22 (24) refers to a groove dimension measured in a direction perpendicular to the extending direction of the widthwise narrow groove 22 (24).

  By making the groove width of the width direction narrow groove 22 (24) 1.0 mm or more, not only can the drainage performance on ice be improved, but also the snow column shear force is increased on snow and braking on snow is performed. The performance can be further improved. On the other hand, by setting the groove width of the width direction narrow groove 22 (24) to 4.0 mm or less, the small blocks B1 and B2 (small blocks B3 and B4) come into contact particularly when an external force in the tire circumferential direction is applied. And support each other. Thereby, the falling of the small blocks B1 to B4 in the tire circumferential direction is suppressed, and the braking performance on ice and the braking performance on snow are further improved.

  In addition, the said effect can be show | played by a higher level each by making the groove width of the width direction fine groove 22 (24) into 2.0 mm or more and 3.0 mm or less.

[Additional Form 6]
In the basic form and the form obtained by adding at least one of the additional forms 1 to 5 to the basic form, the small blocks B1 and B2 (small blocks B3 and B4) adjacent to each other in the tire circumferential direction are shown in FIGS. It is preferable to have the same tire circumferential region (additional form 6).

  4 is a plan view showing the relationship between small blocks B1 and B2 adjacent to each other in the tire circumferential direction in the pneumatic tire shown in FIG. 1 or FIG. 4, (a) is a case where small blocks do not have the same tire circumferential direction area | region, (b) is a case where small blocks have the same tire circumferential direction area | region. In the same figure, regions other than the small block B1 (B11, B12) and the small block B2 (B21, B22) indicate groove regions that partition the small blocks B1, B2. The example shown in FIG. 4 is an example for the blocks B1 and B2 in FIGS. 1 and 3. However, the description of the blocks B1 and B2 shown below also applies to the blocks B3 and B4 shown in FIG.

  In the example shown in FIG. 4 (a), the arrowhead rear end portion of the arrow-shaped small block B11 having anisotropy in the tire circumferential direction and the arrow-shaped small block B21 having anisotropy in the tire circumferential direction. Only the groove exists in the tire circumferential direction region (the region where the tire circumferential direction line segment X continues in the tire width direction in the figure) between the tip of the arrow feather. That is, in the example shown in FIG. 4A, these small blocks B11 and B21 do not have the same tire width direction region.

  On the other hand, in the example shown in FIG. 4B, the arrow feather rear end portion of the arrow-shaped small block B12 having anisotropy in the tire circumferential direction and the arrow feather-shaped having anisotropy in the tire circumferential direction. In the tire circumferential direction region (the region where the tire circumferential direction line segment Y continues in the tire width direction in the same figure) between the tip of the small block B22 and the arrow blade, one of the small blocks B12 and B22 is provided. There is also a department. That is, in the example shown in FIG. 4B, these small blocks B12 and B22 have the same tire circumferential direction region.

  In the present embodiment (additional form 6), the form shown in FIG. 4B is assumed. The example shown in the figure has a smaller tire circumferential dimension of the groove interposed between the small blocks B12 and B22 than the example shown in FIG. For this reason, when an external force in the tire circumferential direction is applied to the small blocks B12 and B22, the small blocks B12 and B22 come into contact with each other and support each other. Thereby, the falling of the small blocks B12 and B22 in the tire circumferential direction is further suppressed, and the braking performance on ice and the braking performance on snow are further improved.

  Similarly, in the example shown in FIG. 4B, the tire width direction dimension of the groove interposed between the small blocks B12 and B22 is smaller than in the example shown in FIG. For this reason, when an external force in the tire width direction is applied to the small blocks B12 and B22, the small blocks B12 and B22 support each other in a region interposed therebetween. Thereby, the fall of the small blocks B12 and B22 in the tire width direction is further suppressed, and the turning performance on ice and the turning performance on snow are further improved.

[Additional Form 7]
In the basic form and the form obtained by adding at least one of the additional forms 1 to 6 to the basic form, at least one sipe is formed in at least one of the small blocks B1 to B4 in each of FIGS. (Additional form 7) is preferred. Here, sipe means a groove having a groove width of 0.4 mm or more and less than 1.0 mm.

  By forming at least one sipe in at least one of the small blocks B1 to B4, it is possible to give more edges to a small block group composed of a plurality of small blocks. Thereby, when the edge by sipe formation contains many components in the tire circumferential direction, the resistance against the external force in the tire width direction is further increased, and the turning performance on ice and the turning performance on snow can be greatly enhanced. Further, when the edge due to sipe formation includes a large amount of the tire width direction component, the resistance against the external force in the tire circumferential direction is further increased, and the braking performance on ice and the braking performance on snow can be greatly enhanced.

  FIG. 5 is a plan view showing a sipe arrangement in the block B1 shown in FIG. 2, wherein (a) is an example in which the sipe S1 extends in the tire width direction, and (b) is a width of the sipe S2. This is an example extending in parallel with the direction narrow groove 22. In the present embodiment, the arrangement of the sipes is not particularly limited. For example, as shown in FIG. 5 (a), when the sipe S1 is extended in the tire width direction, the tire width direction component of the edge due to the sipe formation is maximized, so that the drag force against the external force in the tire circumferential direction is increased. The braking performance on ice and the braking performance on snow can be made extremely high. Further, as shown in FIG. 5B, when the sipe S2 extends in parallel with the widthwise narrow groove 22, one arrow-shaped small block B1 is divided into the same shape by the sipe S2. Thus, the small block piece B1a and the small block piece B1b divided by the sipe S2 perform substantially the same movement with respect to the external force from the tire circumferential direction and the external force from the diamond width direction. For this reason, uneven wear such as local heel and toe wear in the vicinity of the sipe S2 can be suppressed, and the durability performance of the tire can be further enhanced.

The tire size is 195 / 65R15, and has one of the tread patterns shown in FIGS. 1 and 3, and the conditions (1-1) to (8) shown in Table 1, that is, (1-1) the circumferential narrow groove Tire width direction arrangement density (circumferential narrow groove density),
(1-2) How the small block row includes the wide small block and the narrow small block in the tire circumferential direction (formation in the tire circumferential direction of the wide small block and the narrow small block),
(1-3) Bending angle (bending angle) at the bent portion,
(2) Tire circumferential direction arrangement density of width direction narrow grooves (width direction narrow groove density),
(3) Ratio of tire width direction dimension of narrow block to tire width direction dimension of wide small block (ratio of tire width direction dimension of narrow small block),
(4) For a narrow block, the minimum width portion fills a region of 50% or more of the center portion in the tire width direction of the wide block, and the maximum width portion is 90% or less of the center portion of the width direction of the tire in the tire width direction. How much (%) the central small block that fills the area is included in the entire circumference of the tire in the small block row (ratio of central small block)
(5) The width of the circumferential narrow groove,
(6) The width of the narrow groove in the width direction,
(7) Whether or not small blocks adjacent in the tire circumferential direction have the same tire circumferential direction region (presence or absence of the same region in the tire circumferential direction), and (8) at least one sipe is formed in the small block. Whether or not (with or without sipe)
Thus, pneumatic tires of Example 1 to Example 16 were produced. The example shown in FIG. 1 is an example in which the rotation direction of the tire is specified, and the example shown in FIG. 3 is an example in which the rotation direction of the tire is not specified.

  On the other hand, the tire size is 195 / 65R15, and the conventional tread pattern has the same tread pattern as that of Example 1 except that the narrow groove in the width direction extends linearly in the tire width direction without having a bent portion. An example pneumatic tire was made.

  Each of the test tires of Examples 1 to 16 and the conventional example manufactured as described above was assembled to a 15 × 6J rim at an air pressure of 220 kPa and mounted on a sedan type vehicle having a displacement of 1500 CC, and braking performance on ice and on snow The braking performance and drainage performance were evaluated. These results are also shown in Table 1.

(Brake performance on ice)
An index evaluation was performed using the conventional example as a reference (100) by measuring a braking distance from a state where the vehicle traveled at a speed of 40 km / h on an ice board road surface. This evaluation shows that the braking performance on ice is excellent, so that a numerical value is large.

(Brake performance on snow)
An index evaluation was performed using a conventional example as a reference (100) by measuring a braking distance from a state where the vehicle traveled at a speed of 40 km / h on a snowy road surface. This evaluation shows that the larger the value, the better the braking performance on snow.

(Drainage performance)
In the process of accelerating from a stop on a wet road surface with a water depth of 5 mm, an index evaluation was performed using the conventional example as a reference (100) by measuring the speed when the tire grip disappeared and the tire slipped. This evaluation shows that drainage performance is excellent, so that a numerical value is large.

  In Table 1, in the item “presence / absence of the same region in the tire circumferential direction”, “None” means that the dimension X in FIG. 4A is 0.1 mm, and “Yes” means that FIG. In this case, the dimension Y in b) is 1.0 mm. Furthermore, in the item “presence / absence of sipe”, “present” means that a sipe S2 having a shape as shown in FIG. 5B is formed in each small block.

  According to Table 1, it belongs to the technical scope of the present invention (peripheral narrow groove density, formation mode in the tire circumferential direction of the wide narrow block and the narrow narrow block, and the bend angle are given predetermined improvements). For the pneumatic tires of Example 1 to Example 16, all of which are not within the technical scope of the present invention, braking performance on ice and braking performance on snow, compared to conventional pneumatic tires, It can be seen that drainage performance is improved in a well-balanced manner.

  The present invention includes the following aspects.

(1) A plurality of small block rows adjacent in the tire width direction are partitioned by a plurality of circumferential narrow grooves and a plurality of width narrow grooves intersecting with the circumferential narrow grooves. In the pneumatic tire, the circumferential narrow groove is disposed at a tire width direction density of 0.06 / mm or more and 0.2 / mm or less, and the width narrow groove has at least one bent portion. And the small block row includes a wide small block and a narrow small block, and a bending angle at the bent portion is 40 ° or more and 160 ° or less.

(2) The pneumatic tire according to (1), wherein the widthwise narrow grooves are disposed at a tire circumferential density of 0.04 / mm or more and 0.3 / mm or less.

(3) The pneumatic tire according to (1) or (2), wherein a tire width direction dimension of the narrow block is 60% or more and 90% or less of a tire width direction dimension of the wide block.

(4) In the narrow and narrow block, the minimum width portion fills an area of 50% or more of the center portion in the tire width direction of the wide and narrow block, and the maximum width portion is 90% or less of the center portion in the tire width direction of the wide and narrow block. The pneumatic tire according to any one of (1) to (3), including a central small block that satisfies the region of 30% or more in the entire circumference of the tire in the small block row.

(5) The pneumatic tire according to any one of (1) to (4), wherein a groove width of the circumferential narrow groove is 1.0 mm or greater and 10.0 mm or less.

(6) The pneumatic tire according to any one of (1) to (5), wherein a width of the narrow groove in the width direction is 1.0 mm or greater and 4.0 mm or less.

(7) The pneumatic tire according to any one of (1) to (6), wherein the small blocks adjacent in the tire circumferential direction have the same tire circumferential direction region.

(8) The pneumatic tire according to any one of (1) to (7), wherein at least one sipe is formed in at least one of the small blocks.

DESCRIPTION OF SYMBOLS 1, 2 Pneumatic tire 10, 11 Tread part 12, 13 Tread surface 14 Circumferential main groove 18, 18a, 18b Circumferential narrow groove 22, 22a, 22b, 24, 24a, 24b Width direction narrow groove A Vertex of bending part B1, B2, B3, B4, B11, B12, B21, B22 Small block B1a, B1b Small block piece CL Tire equatorial plane E Ground contact edge L Center line in the tire width direction within the tire width direction region R Tire width at the bent portion Tire width direction region from one end of the direction to the other end S1, S2 Sipe X Tire circumferential direction region between the arrow wing rear end of the small block B11 and the arrow wing tip of the small block B21 Y Tire circumferential direction region between the rear end portion of the arrow W of the small block B12 and the end portion of the arrow feather of the small block B22 θ Bending angle at the bending portion

Claims (8)

While having a circumferential main groove,
In a pneumatic tire in which a plurality of small block rows adjacent to each other in the tire width direction are partitioned by a plurality of circumferential narrow grooves and a plurality of width-direction narrow grooves intersecting with the circumferential narrow grooves,
The circumferential narrow grooves are disposed at a tire width direction density of 0.06 / mm or more and 0.2 / mm or less,
The widthwise narrow groove has at least one bent portion;
The small block row includes a wide small block and a narrow small block,
Ri 160 ° der less bending angle is 40 ° or more at the bent portion,
The bending angle is an inferior angle among the angles formed by the widthwise narrow grooves .
Pneumatic tire.   The pneumatic tire according to claim 1, wherein the narrow grooves in the width direction are arranged at a tire circumferential density of 0.04 / mm or more and 0.3 / mm or less.   The pneumatic tire according to claim 1 or 2, wherein a dimension in the tire width direction of the narrow block is 60% or more and 90% or less of a dimension in the tire width direction of the wide block. The narrow block is
A central small block in which a minimum width portion fills a region of 50% or more of the center portion in the tire width direction of the wide small block and a maximum width portion fills a region of 90% or less of the center portion in the tire width direction of the wide small block. ,
Unrealized 30% or more in the tire entire circumference of the small block row,
The tire width direction central portion is a tire width direction in a tire width direction region from one end of the bent portion in the tire width direction to the other end when focusing on one wide and small block. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is a portion that exists symmetrically on both sides in the tire width direction including the center line with respect to the center line .   The pneumatic tire according to any one of claims 1 to 4, wherein a groove width of the circumferential narrow groove is 1.0 mm or greater and 10.0 mm or less.   The pneumatic tire according to any one of claims 1 to 5, wherein a groove width of the narrow groove in the width direction is 1.0 mm or greater and 4.0 mm or less. In the tire width direction region of two small blocks adjacent to each other in the tire circumferential direction, the position in the tire circumferential direction rear end side of one of the small blocks and the position in the tire circumferential direction front end side of the other small block 7 is adjacent to each other, and at any position in the tire circumferential direction between these positions, not only the narrow groove in the width direction but also a part of the small block exists. The described pneumatic tire.   The pneumatic tire according to any one of claims 1 to 7, wherein at least one sipe is formed in at least one of the small blocks.

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