JP2015054594A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire in which brake performance on ice, brake performance on snow, and drainage performance are improved in a well-balanced manner.SOLUTION: Circumferential narrow grooves 18 are disposed at a tire width direction density of 0.06 pcs/mm to 0.2 pcs/mm. A width direction narrow groove 22 has at least one bent part. A bend angle θ in the bent part is 40° or more and 160° or less. The circumferential narrow groove 18 and a circumferential main groove 14 have at least one recess 18a and one recess 14a, respectively, at least in a part of a tire circumferential region adjacent to small blocks constituting an a row of small blocks.

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, and a plurality of small block rows are defined by a plurality of circumferential narrow grooves and a plurality of widthwise narrow grooves intersecting with the circumferential narrow grooves. A pneumatic tire. 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 bending angle at the bent portion is not less than 40 ° and not more than 160 °. The circumferential main groove and the circumferential narrow groove have at least one recess that protrudes to one side in the tire width direction in at least a part of a tire circumferential region adjacent to each small block constituting the small block row. .

  In the pneumatic tire according to the present invention, the arrangement density of the circumferential narrow grooves in the tire width direction is improved, and the bending angle of the bent portions is improved on the premise that the bent portions are provided in the widthwise narrow grooves. In addition, the shape of the circumferential narrow groove is 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 variation of the small block according to the embodiment of the present invention. FIG. 4 is a plan view showing a tread portion of the pneumatic tire according to the embodiment of the present invention. 5 is a plan view showing the relationship between small blocks B1 (B2) adjacent to each other in the tire circumferential direction in the pneumatic tire shown in FIG. 1 or FIG. 4, and (a) is a tire circumferential direction in which the small blocks are the same. This is a case where there is no region, and (b) is a case where the small blocks have the same tire circumferential direction region. 6 is a plan view showing a sipe arrangement mode for the small 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. It is an example extended in parallel with a narrow groove.

  Hereinafter, embodiments of the pneumatic tire according to the present invention (basic modes and additional modes 1 to 8 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, grooves 14 and 18 extending in the tire circumferential direction and grooves 22 inclined with respect to the tire circumferential direction are respectively provided on the tread surface 12 to form the tread pattern shown in FIG. Has been. The specific configuration of the grooves 14 to 22 is as follows.

  That is, the tread surface 12 is provided with two circumferential main grooves 14 that are symmetrical with respect to the tire equatorial plane CL, extend in the tire circumferential direction, and change in the width direction in the middle of the tire circumferential direction. ing. 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.

  As described above, in the example illustrated in FIG. 1, the two circumferential main grooves 14 and the plurality of circumferential narrow grooves 18 (for example, the grooves 181 and 182), and the plurality of widthwise narrow grooves intersecting with the circumferential narrow grooves 18. A plurality of small block rows adjacent in the tire width direction are formed by the grooves 22 (for example, the grooves 221 and 222). 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. In the present embodiment, the groove width of the circumferential main groove 14 means a dimension including a recess 14a that protrudes in the tire width direction while extending in the tire circumferential direction.

  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. That is, 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 181 and 182) with respect to one width-direction narrow groove 22.

  Further, in the present embodiment, as shown in FIG. 2 (a plan view showing an enlargement of the periphery of the circled portion of the tread portion shown in FIG. 1), the bending angle θ at the bending portion of the width direction narrow groove 22 is 40. It is at least 160 ° and no more. The bent portion is not limited to one formed by two linear portions between the circumferential narrow grooves 181 and 182 adjacent to each other in the tire width direction as shown in FIG. , 182 extending in a curved shape is also included. When the bent portion extends in a curved line, the angle is an angle formed by straight lines extending from both ends of the bent portion in the tire width direction to the vertex A of the bent portion.

  In addition, in the present embodiment, as shown in FIG. 1, the circumferential narrow groove 18 and the circumferential main groove 14 are at least one of the tire circumferential region adjacent to each small block B1 constituting the small block row. At least one recess 18a, 14a projecting on one side in the tire width direction.

  For example, as shown in FIG. 2, the circumferential narrow grooves 181 and 182 are respectively provided with recesses 18 a and 18 a that protrude to one side in the tire width direction in a part of the tire circumferential region adjacent to each small block B <b> 1. Each circumferential narrow groove 181, 182 is provided on both sides.

  Thereby, the small block B1 has a shape as shown in FIG. 2, that is, has anisotropy in the tire circumferential direction and is recessed in the tire width direction at both outer side portions in the tire width direction.

  The shape of the small block B1 is not limited to the shape shown in FIG. That is, the shape of the small block B1 includes any shape as long as it has anisotropy in the tire circumferential direction and is recessed in the tire width direction on at least one side in the tire width direction. Examples of variations in the shape of the small block B1 include the shapes shown in FIGS. 3A to 3U. In the example shown in FIGS. 3A to 3F, there is a profile line of a small block adjacent to the circumferential narrow groove (circumferential main groove) (hereinafter sometimes referred to as “small block profile line”). In this example, only the central region in the tire circumferential direction is recessed in the tire width direction. The example shown in FIG. 3G to FIG. 3L is an example in which the small block profile line is recessed in the tire width direction only at one end region in the tire circumferential direction (lower region on the paper surface). The example shown in FIG. 3 (m) to FIG. 3 (r) is an example in which the small block profile line is recessed in the tire width direction only at the other end region in the tire circumferential direction (upper region on the paper surface). The example shown in FIG. 3 (s) to FIG. 3 (u) is an example in which the small block profile line is recessed in the tire width direction in the entire region in the tire circumferential direction.

  Further, as another variation of the shape of the small block B1, although not shown, the small block profile line on one side is one of the lines in FIGS. 3A to 3U, and the small block B1 on the other side is small. A straight line extending in the tire circumferential direction without a concave block profile line is also included. Further, other variations of the shape of the small block B1 include a combination of the small block profile lines on one side of each of FIGS. 3A to 3U, although not shown.

(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 circumferential direction length of the small block B1 is It can suppress making it too small with respect to the tire width direction length. Thereby, the collapse of the small block B1 in the tire circumferential direction is suppressed, sufficient resistance against the external force in the tire circumferential direction is ensured, and excellent braking performance on ice and excellent braking performance on snow are exhibited. be able to.

  On the other hand, in the pneumatic tire of the present embodiment, the circumferential narrow grooves 18 are disposed in a tire width direction density of 0.2 / mm or less so as to zigzag in the tire width direction of the small block B1. A sufficient edge component in the tire width direction can be secured for existing edges. 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 into 0.08 piece / mm or more and 0.12 piece / mm or less.

  Further, in the pneumatic tire of the present embodiment, by providing at least one bent portion in the widthwise narrow groove 22, the shape of the small block B1 partitioned by the widthwise narrow groove 22 is anisotropic, In FIG. 1, anisotropy in the tire circumferential direction is given. 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 grounding side (stepping side) of the small block B1 defined by the width direction narrow groove 22 is the apex of the V shape. It can be. Thereby, water can be efficiently discharged | emitted from the width direction fine groove 22, and drainage performance can be improved.

  Furthermore, in the pneumatic tire of the present embodiment, by setting the bending angle θ at the bent portion to 40 ° or more, the edge of the small block B1 defined by the width-direction narrow groove 22 is formed in the tire width direction. Enough edge component. 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 of the small block B1 defined by the widthwise narrow grooves 22 has a sufficient edge component in the tire circumferential direction. 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.

  In addition, in the pneumatic tire according to the present embodiment, as shown in FIG. 1, the circumferential direction of the tire is adjacent to each of the small blocks B1 constituting the small block row in the circumferential narrow groove 18 and the circumferential main groove 14. At least one of the recesses 18a and 14a protruding to one side in the tire width direction is included in at least a part of the region. Thereby, a narrow portion in the tire width direction can be formed in the small block B1, and the width of the circumferential narrow groove 18 (and the circumferential main groove 14) can be locally secured. For this reason, even when the small block B1 falls in the tire width direction, a gap remains on both outer sides in the tire width direction of the small block B1. As a result, a sufficient snow column shearing force (the force by which the tire shears the snow column formed by stepping on snow) is ensured, and excellent turning performance on snow can be realized. Further, as described above, the gaps remain on both outer sides in the tire width direction of the small block B1, so that the drag against the external force in the tire width direction is efficiently generated by the edges on the both outer sides in the tire width direction of the small block B1. be able to. As a result, excellent turning performance on snow can be achieved.

  As described above, the pneumatic tire according to the present embodiment is improved on the arrangement density of the circumferential narrow grooves in the tire width direction, and on the premise that a bent portion is provided in the wide narrow grooves. The bending angle of the bent portion is improved, and the shape of the circumferential narrow groove 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. 4 is a plan view showing a tread portion of the pneumatic tire according to the embodiment of the present invention (a view of a 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. 4 is made of a rubber material (tread rubber), similar 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. 4, two circumferential main grooves 14 and a plurality of circumferential narrow grooves 20 (for example, grooves 201 and 202), and a plurality of width-direction narrow grooves 24 intersecting these circumferential narrow grooves 20. (For example, 241 and 242) form a plurality of small block rows adjacent in the tire width direction.

  Under such a premise, also in the present embodiment (basic form 2), the circumferential narrow grooves 20 are disposed at a tire width direction density of 0.06 / mm or more and 0.2 / mm or less. The direction narrow groove 24 has at least one bent portion as shown in FIG. Further, the bend angle θ at the bent portion is 40 ° or more and 160 ° or less, and the circumferential narrow groove 20 and the circumferential main groove 14 are adjacent to the small blocks B1 and B2 constituting the small block row. At least one of the recesses 20a and 14a protruding to one side in the tire width direction is provided in at least a part of the direction area.

  Note that the small block B1 and the small block B2 have the same size and opposite directions in the tire circumferential direction. In the example shown in FIG. 4, a small block row in which a plurality of small blocks B1 are formed in the tire circumferential direction and a small block row in which a plurality of small blocks B2 are formed in the tire circumferential direction are alternately arranged in the tire width direction. Is formed.

  As shown above, also in the pneumatic tire according to the basic form 2, the arrangement density in the tire width direction of the circumferential narrow grooves is improved, and on the premise that the bent portion is provided in the width narrow grooves. The bending angle of the bent portion is improved, and the shape of the circumferential narrow groove 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 embodiments 1 to 8 that can be optionally implemented with respect to the basic embodiment 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.

  By arranging the width direction narrow grooves 22 and 24 at a circumferential density of 0.04 / mm or more, the tire width direction length of each of the small blocks B1 and B2 is the tire circumferential direction length. Can be suppressed from being excessively small. Thereby, the collapse of the small blocks B1 and B2 in the tire width direction can be suppressed, and a sufficient resistance to 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 edges extending in the tire circumferential direction formed in the small blocks B1 and B2 are 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, the area of the recesses 18a, 20a, and 14a is 4 mm ² or more and 40 mm ² or less in each of FIGS. preferable.

By setting the area of the recesses 18a, 20a, and 14a to 4 mm ² or more, drainage paths from the circumferential narrow grooves 18 and 20 and the circumferential main groove 14 to both sides in the tire width direction are secured, thereby improving drainage performance. Is done. Further, by setting the area of the recesses 18a, 20a, and 14a to 4 mm ² or more, even when the small blocks B1 and B2 collapse in the tire width direction on the snowy road surface, the small blocks B1 that are adjacent in the tire width direction, Snow sufficiently enters between B1 and between small blocks B1 and B2. As a result, a sufficient snow column shear force is ensured, and excellent turning performance on snow can be exhibited.

On the other hand, by setting the area of the recesses 18a, 20a, and 14a to 40 mm ² or less, it is possible to secure ten parts of land portion rigidity of the small block row, thereby improving the braking performance on ice and the braking performance on snow. it can.

[Additional form 3]
In the basic form and the form obtained by adding the additional form 1 or 2 to the basic form, in each of FIGS. 1 and 4, the recesses 18 a, 20 a, and 14 a exist in the region of 25% of each outer part in the tire width direction of the small block. (Additional form 3) is preferred.

  Here, the region of each outer portion 25% in the tire width direction of each of the small blocks B1 and B2 is, for example, for the small block B1, as shown in FIG. 2, from one end portion in the tire width direction to the other side. This is a region X25 of 25% of each outer portion in the tire width direction in the tire width direction region X100 to the end of the tire. In addition, also about the small block B2 shown in FIG. 3, the interpretation about the area | region of each outer side 25% of a tire width direction is the same as the case of the small block B1 mentioned above.

  By providing the recesses 18a, 20a, 14a in the regions of the outer portions 25% of the small blocks B1, B2 in the tire width direction, the areas of the small blocks B1, B2 are sufficiently secured, and their rigidity is sufficient. Can be secured. As a result, braking performance on ice and braking performance on snow can be improved.

[Additional form 4]
In the basic form and the form in which at least one of the additional forms 1 to 3 is added to the basic form, in each of FIGS. 20 or the circumferential main groove 14 is preferably present in the region of the tire circumferential direction center 80% of the tire circumferential direction adjacent region (additional form 4).

  Here, the region of the tire circumferential direction central portion 80% in the tire circumferential region where the small blocks B1 and B2 and the circumferential narrow grooves 18 and 20 (circumferential main grooves 14) are adjacent is, for example, a small block As shown in FIG. 2, B <b> 1 refers to a region Y <b> 80 of the tire circumferential direction center portion 80% in the tire circumferential region Y <b> 100 adjacent to the circumferential narrow groove 18. In addition, also about the small block B2 shown in FIG. 3, the interpretation about the area | region of tire peripheral direction center part 80% is the same as the case of the small block B1 mentioned above.

  Recesses 18a, 20a, 14a are present in the region of the tire circumferential center 80% of the tire circumferential region where the small blocks B1, B2 and the circumferential narrow grooves 18, 20 or the circumferential main groove 14 are adjacent to each other. By doing so, the snow column shear force can be increased while increasing the rigidity of the small blocks B1 and B2 and suppressing the collapse of the small blocks B1 and B2 in the tire circumferential direction. As a result, braking performance on ice and braking performance on snow can be improved.

  In the present embodiment, the recesses 18a and 20a (recesses 14a) of the circumferential narrow grooves 18 and 20 (circumferential main grooves 14) are formed as shown in FIG. 1 and FIG. 20 (circumferential main groove 14) can be formed on both sides in the tire width direction with respect to a tire width direction center line (not shown). In this case, the circumferential positions of the recesses 18a and 20a (recesses 14a) formed on both sides of the same groove 18 and 20 (14) in the tire width direction may be the same or different. However, as shown in FIG. 2, when the circumferential positions of the recesses 14 a formed on both sides in the tire width direction are the same, both of the small blocks B <b> 1 in the tire width direction are applied when an external force in the tire width direction is applied. Larger gaps remain on the outside. For this reason, a larger snow column shear force is ensured, and the turning performance on snow is further improved.

[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 widths of the circumferential narrow grooves 18 and 20 are 1.0 mm or more and 10.0 mm in each of FIGS. The following (additional form 5) is preferred. Here, the groove width of the circumferential narrow grooves 18 and 20 refers to a groove dimension measured in a direction perpendicular to the extending direction of the circumferential narrow grooves 18 and 20.

  By setting the groove width of the circumferential narrow grooves 18 and 20 to 1.0 mm or more, drainage performance on ice can be further enhanced. Further, by setting the groove width to 10.0 mm or less, when an external force in the tire width direction is applied, the small blocks adjacent to each other in the tire width direction that are partitioned by the common circumferential narrow grooves 18 and 20 are formed. (The small blocks B1 and B1 in the example shown in FIG. 1 and the small blocks B1 and B2 in the example shown in FIG. 4) come into contact with each other and support each other. Thereby, falling of the small blocks B1 and B2 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 grooves 18 and 20 into 2.0 mm or more and 8.0 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 groove widths of the width-direction narrow grooves 22 and 24 in each of FIGS. It is preferably 0 mm or less (additional form 6). Here, the groove width of the width direction narrow grooves 22 and 24 refers to a groove dimension measured in a direction perpendicular to the extending direction of the width direction narrow grooves 22 and 24.

  By making the width of the narrow grooves 22 and 24 equal to or greater than 1.0 mm, not only the drainage performance on ice can be further improved, but also the snow column shear force increases on snow, and braking performance on snow. Can be further improved. On the other hand, when the groove widths of the width-direction narrow grooves 22 and 24 are set to 4.0 mm or less, the small blocks B1 and B1 (small blocks B2 and B2) come into contact particularly when an external force in the tire circumferential direction is applied. Support each other. Thereby, the falling of the small blocks B1 and B2 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 grooves 22 and 24 into 2.0 mm or more and 3.0 mm or less.

[Additional Form 7]
In the basic form and the form in which at least one of the additional forms 1 to 6 is added to the basic form, in each of FIGS. It is preferable to have the same tire circumferential direction region (additional form 7).

  FIG. 5 is a plan view showing the relationship between the small blocks B1 and B1 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 figure, the area other than the small block B1 (B11, B12, B13, B14) indicates a groove area that partitions the small block B1. The example shown in FIG. 5 is an example for the small block B1 of FIGS. 1 and 4, but the description of the small block B1 shown below also applies to the small block B2 shown in FIG.

  In the example shown in FIG. 5A, the rear end portion of the arrow feather B11 having anisotropy in the tire circumferential direction and the arrow feather small block B12 having anisotropy in the tire circumferential direction. There is only a groove in the tire circumferential region between the tip of the arrow blades (the region in which the tire circumferential line segment H1 continues in the tire width direction in the figure). That is, in the example shown in FIG. 5A, these small blocks B11 and B12 do not have the same tire width direction region.

  On the other hand, in the example shown in FIG. 5B, the arrow feather rear end portion of the arrow-shaped small block B13 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 (region where the tire circumferential direction line segment H2 is continuous in the tire width direction in the same figure) between the tip of the small block B14 and the arrow blade, one of the small blocks B13 and B14 is provided. There is also a department. That is, in the example shown in FIG. 5B, these small blocks B13 and B14 have the same tire circumferential direction region.

  In the present embodiment (additional form 7), the form shown in FIG. 5B is assumed. The example shown in the figure has a smaller tire circumferential dimension of the groove interposed between the small blocks B13 and B14 than the example shown in FIG. For this reason, when an external force in the tire circumferential direction is applied to the small blocks B13 and B14, the small blocks B13 and B14 come into contact with each other and support each other. Thereby, the falling of the small blocks B13 and B14 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. 5B, the tire width direction dimension of the groove interposed between the small blocks B13 and B14 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 B13 and B14, the small blocks B13 and B14 support each other in a region interposed therebetween. Thereby, the fall of the small blocks B13 and B14 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 8]
In the basic form and the form obtained by adding at least one of the additional forms 1 to 7 to the basic form, at least one sipe is formed in at least one of the small blocks B1 and B2 in FIGS. (Additional form 8) 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 and B2, 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. 6 is a plan view showing a sipe arrangement in the small 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 sipe S2. This is an example extending in parallel to the widthwise narrow groove 22. In the present embodiment, the arrangement of the sipes is not particularly limited. For example, as shown in FIG. 6 (a), when the sipe S1 is extended in the tire width direction, the tire width direction component of the edge due to 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. In addition, as shown in FIG. 6B, 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 it has one of the tread patterns shown in FIGS. 1 and 4, and the conditions (1-1) to (9) shown in Table 1, that is, (1-1) of the circumferential narrow groove Tire width direction arrangement density (circumferential narrow groove density),
(1-2) Whether the widthwise narrow groove includes a bent portion (existence of the bent portion)
(1-3) Bending angle (bending angle) at the bent portion,
(1-4) The circumferential main groove and the circumferential narrow groove have at least one recess that protrudes to one side in the tire width direction in at least a part of the tire circumferential region adjacent to each small block constituting the small block row. Whether or not there are (recesses)
(2) Tire circumferential direction arrangement density of width direction narrow grooves (width direction narrow groove density),
(3) the area of the recess,
(4) Tire width direction existence area of recesses with respect to tire width direction area of small blocks (tire width direction existence area of recesses)
(5) Tire circumferential direction existence area of a recess with respect to a tire circumferential direction area adjacent to a circumferential narrow groove of a small block (tire circumferential direction existence area of a depression)
(6) Groove width of circumferential narrow groove,
(7) The width of the narrow groove in the width direction,
(8) Whether or not the small blocks adjacent to each other in the tire circumferential direction have the same tire circumferential direction region (the presence or absence of the same region in the tire circumferential direction), and (9) 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 18 were produced. The example shown in FIG. 1 is an example in which the tire rotation direction is specified, and the example shown in FIG. 4 is an example in which the tire rotation direction is not specified.

  In contrast, the tire size of 195 / 65R15, the widthwise narrow groove does not have a bent portion, and neither the circumferential main groove nor the circumferential narrow groove has a concave portion. A conventional pneumatic tire having the same tread pattern as the pattern was produced.

  Each of the test tires of Examples 1 to 18 and the conventional example manufactured as described above was assembled on 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 H1 in FIG. 5A is 0.1 mm, and “Yes” means that FIG. In this case, the dimension H2 in b) is 1.0 mm. Further, in the item “presence / absence of sipe”, “present” means that a sipe S2 having a shape as shown in FIG. 6B is formed in each small block.

  According to Table 1, the pneumatic tires of Examples 1 to 18 belonging to the technical scope of the present invention (with improvements in the circumferential narrow groove density, the bending angle of the bent portion, and the presence of the recessed portion). As for, braking performance on ice, braking performance on snow, and drainage performance are improved in a well-balanced manner compared to conventional pneumatic tires that are not within the technical scope of the present invention. I understand.

  The present invention includes the following aspects.

(1) In a pneumatic tire having a circumferential main groove, and a plurality of circumferential narrow grooves and a plurality of widthwise narrow grooves intersecting with the circumferential narrow grooves, wherein a plurality of small block rows are partitioned and formed. The circumferential narrow groove is disposed at a tire width direction density of 0.06 / mm or more and 0.2 / mm or less, the width narrow groove has at least one bent portion, and the bent portion And the circumferential main groove and the circumferential narrow groove are tire widths in at least a part of a tire circumferential region adjacent to each small block constituting the small block row. A pneumatic tire having at least one recess protruding on one side in the direction.

(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 an area of the recess is 4 mm ² or more and 40 mm ² or less.

(4) The pneumatic tire according to any one of (1) to (3), wherein the concave portion is present in a region of each outer portion 25% of the small block in the tire width direction.

(5) The concave portion is present in a region of the tire circumferential direction central portion 80% of the tire circumferential region where the small block and the circumferential main groove or the circumferential narrow groove are adjacent to each other. The pneumatic tire according to any one of (1) to (4).

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

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

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

(9) The pneumatic tire according to any one of (1) to (8), 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, 181, 182 Circumferential narrow groove 22, 221, 222, 24, 241, 242 Wide narrow groove 14a, 18a Recess A Vertex B1, B11, B12, B13, B14, B2 Small block B1a, B1b Small block piece CL Tire equatorial plane E Ground contact edge H1, H2 Tire circumferential direction line segment S1, S2 Sipe X100 Bending portion in tire width direction Tire width direction region X25 from one side end to the other side end X25 Region of tire outer side 25% in tire width direction region X100 Y100 Adjacent to circumferential narrow groove 18 of small block B1 Tire circumferential area Y80 The tire circumferential area 80% of the tire circumferential area Y100 is the area of the tire circumferential direction 80%. Bending angle

Claims (9)

In a pneumatic tire having a circumferential main groove and a plurality of circumferential narrow grooves and a plurality of widthwise narrow grooves intersecting the circumferential narrow grooves, a plurality of small block rows are partitioned and formed.
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 bending angle at the bent portion is 40 ° or more and 160 ° or less,
The circumferential narrow groove and the circumferential main groove have at least one recess that protrudes to one side in the tire width direction in at least a part of a tire circumferential region adjacent to each small block constituting the small block row. ,
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 an area of the recess is 4 mm ² or more and 40 mm ² or less.   The pneumatic tire according to any one of claims 1 to 3, wherein the concave portion exists in a region of each outer portion 25% of the small block in the tire width direction.   The said recessed part exists in the area | region of the tire circumferential direction center part 80% of the tire circumferential direction area | region where the said small block and the said circumferential direction fine groove or the said circumferential direction main groove are adjacent. The pneumatic tire according to any one of 4.   The pneumatic tire according to any one of claims 1 to 5, 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 6, wherein a groove width of the narrow groove in the width direction is 1.0 mm or greater and 4.0 mm or less.   The pneumatic tire according to any one of claims 1 to 7, wherein the small blocks adjacent to each other in the tire circumferential direction have the same tire circumferential direction region.   The pneumatic tire according to any one of claims 1 to 8, wherein at least one sipe is formed in at least one of the small blocks.

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