JP2016147654A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving on-snow performance of the tire.SOLUTION: A pneumatic tire 1 has a tread surface provided with land parts 31-33 with a rib or a plurality of blocks. The pneumatic tire 1 also comprises an attachment direction indication part for indicating a direction of attachment to a vehicle. Additionally, the land parts 31-33 have a plurality of thin shallow grooves 7 and a plurality of recesses 8 provided on a ground contact surface. Furthermore, an opening area ratio Sin of the recess 8 in a vehicle width direction inside area, in which a tire equator surface CL serves as a boundary, and an opening area ratio Sout of the recess 8 in a vehicle width direction outside area have a relationship: Sin<Sout.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can improve the performance of the tire on snow.

  In a general new tire, since chemicals adhere to the tread surface, there is a problem that the water absorption action and the edge action of the block at the initial stage of wear are small, and the braking performance on ice is low. For this reason, in recent studless tires, a configuration is adopted in which a plurality of shallow fine grooves are provided on the surface of the block. In such a configuration, the on-ice braking performance of the tire is improved by removing the water film in which the shallow groove is interposed between the ice road surface and the tread surface in the early stage of wear. As a conventional pneumatic tire employing such a configuration, a technique described in Patent Document 1 is known.

Japanese Patent No. 3702958

  On the other hand, in a pneumatic tire, there is also a problem that should improve the performance of the tire on snow.

  Therefore, the present invention has been made in view of the above, and an object thereof is to provide a pneumatic tire that can improve the performance of the tire on snow.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a land portion having a rib or a plurality of blocks on a tread surface, and a pneumatic tire including a mounting direction display unit that displays a mounting direction with respect to a vehicle. The land portion includes a plurality of shallow grooves and a plurality of recesses on a ground contact surface, and a ratio of a sum of opening areas of the recesses in a predetermined region and a contact area of the land portion is defined as an opening area ratio of the recesses. The opening area ratio Sin of the concave portion in the vehicle width direction inner region defined by the tire equator plane and the opening area ratio Sout of the concave portion in the vehicle width direction outer region have a relationship of Sin <Sout. It is characterized by that.

  In the pneumatic tire according to the present invention, when the tire is mounted on a vehicle having a negative camber, the contact pressure in the outer region in the vehicle width direction of the tire is relatively low. At this time, since the opening area ratio Sin of the concave portion in the inner region in the vehicle width direction is large, the ground contact area in the outer region in the vehicle width direction decreases, the ground contact pressure increases, and the snow column shear force by the concave portion increases. Thereby, there exists an advantage which the traction performance of a tire improves and the on-snow performance of a tire improves.

FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a plan view showing a tread surface of the pneumatic tire depicted in FIG. 1. FIG. 3 is an explanatory diagram illustrating a land portion of the pneumatic tire illustrated in FIG. 2. FIG. 4 is an enlarged view showing a main part of the block shown in FIG. FIG. 5 is a cross-sectional view taken along line AA of the ground contact surface of the block illustrated in FIG. 4. FIG. 6 is an explanatory diagram showing a land portion of the pneumatic tire depicted in FIG. 2. FIG. 7 is an explanatory diagram illustrating a land portion of the pneumatic tire illustrated in FIG. 2. FIG. 8 is an explanatory view showing a modification of the pneumatic tire shown in FIG. FIG. 9 is an explanatory diagram showing a modified example of the pneumatic tire depicted in FIG. 4. FIG. 10 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 4. FIG. 11 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 4. FIG. 12 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 4. FIG. 13 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 4. FIG. 14 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 4. FIG. 15 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 4. FIG. 16 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 4. FIG. 17 is an explanatory diagram showing a modification of the pneumatic tire depicted in FIG. FIG. 18 is an explanatory view showing a modified example of the pneumatic tire depicted in FIG. 4. FIG. 19 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 4. FIG. 20 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 4. FIG. 21 is an explanatory view showing a modified example of the pneumatic tire depicted in FIG. 4. FIG. 22 is an explanatory view showing a modified example of the pneumatic tire depicted in FIG. 2. FIG. 23 is an explanatory diagram showing a modified example of the pneumatic tire depicted in FIG. 2. FIG. 24 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention. FIG. 25 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Pneumatic tire]
FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. The same figure has shown sectional drawing of the one-side area | region of a tire radial direction. The figure shows a radial tire for a passenger car as an example of a pneumatic tire.

  In the figure, the cross section in the tire meridian direction means a cross section when the tire is cut along a plane including a tire rotation axis (not shown). Reference sign CL denotes a tire equator plane, which is a plane that passes through the center point of the tire in the tire rotation axis direction and is perpendicular to the tire rotation axis. Further, the tire width direction means a direction parallel to the tire rotation axis, and the tire radial direction means a direction perpendicular to the tire rotation axis.

  The pneumatic tire 1 has an annular structure centered on the tire rotation axis, and includes a pair of bead cores 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, and a tread rubber 15. And a pair of sidewall rubbers 16 and 16 and a pair of rim cushion rubbers 17 and 17 (see FIG. 1).

  The pair of bead cores 11 and 11 is an annular member formed by bundling a plurality of bead wires, and constitutes the core of the left and right bead portions. The pair of bead fillers 12 and 12 are disposed on the outer circumference in the tire radial direction of the pair of bead cores 11 and 11 to constitute a bead portion.

  The carcass layer 13 has a single layer structure composed of a single carcass ply or a multilayer structure formed by laminating a plurality of carcass plies, and is bridged in a toroidal shape between the left and right bead cores 11 and 11 to form a tire skeleton. Configure. Further, both end portions of the carcass layer 13 are wound and locked outward in the tire width direction so as to wrap the bead core 11 and the bead filler 12. The carcass ply of the carcass layer 13 is formed by coating a plurality of carcass cords made of steel or an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with a coat rubber and rolling it, and has an absolute value of 80 A carcass angle (inclination angle in the fiber direction of the carcass cord with respect to the tire circumferential direction) of [deg] or more and 95 [deg] or less.

  The belt layer 14 is formed by laminating a pair of cross belts 141 and 142 and a belt cover 143, and is arranged around the outer periphery of the carcass layer 13. The pair of cross belts 141 and 142 is formed by rolling a plurality of belt cords made of steel or organic fiber material with a coating rubber, and has an absolute value of a belt angle of 20 [deg] or more and 55 [deg] or less. Have. Further, the pair of cross belts 141 and 142 have belt angles with different signs from each other (inclination angle of the fiber direction of the belt cord with respect to the tire circumferential direction), and are laminated so that the fiber directions of the belt cords cross each other. (Cross ply structure). The belt cover 143 is formed by rolling a plurality of cords made of steel or organic fiber material covered with a coat rubber, and has a belt angle of 0 [deg] or more and 10 [deg] or less in absolute value. Further, the belt cover 143 is disposed so as to be laminated on the outer side in the tire radial direction of the cross belts 141 and 142.

  The tread rubber 15 is disposed on the outer circumference in the tire radial direction of the carcass layer 13 and the belt layer 14 to constitute a tread portion of the tire. The pair of side wall rubbers 16 and 16 are respectively arranged on the outer side in the tire width direction of the carcass layer 13 to constitute left and right side wall portions. The pair of rim cushion rubbers 17, 17 are respectively disposed on the inner side in the tire radial direction of the wound portions of the left and right bead cores 11, 11 and the carcass layer 13, and constitute the contact surfaces of the left and right bead portions with respect to the rim flange.

[Tread pattern]
FIG. 2 is a plan view showing a tread surface of the pneumatic tire depicted in FIG. 1. The figure shows a tread pattern of a studless tire. In the figure, the tire circumferential direction refers to the direction around the tire rotation axis. Moreover, the code | symbol T is a tire grounding end.

  As shown in FIG. 2, the pneumatic tire 1 includes a plurality of circumferential main grooves 21 and 22 that extend in the tire circumferential direction, and a plurality of land portions 31 to 31 that are partitioned by the circumferential main grooves 21 and 22. 33 and a plurality of lug grooves 41 to 43 arranged in these land portions 31 to 33 are provided in the tread portion.

  The circumferential main groove is a circumferential groove having a wear indicator indicating the end of wear, and generally has a groove width of 5.0 [mm] or more and a groove depth of 7.5 [mm] or more. The lug groove means a lateral groove having a groove width of 2.0 [mm] or more and a groove depth of 3.0 [mm] or more.

  The groove width is measured as the maximum value of the distance between the left and right groove walls at the groove opening in a no-load state in which the tire is mounted on the prescribed rim and filled with the prescribed internal pressure. In the configuration where the land part has a notch part or a chamfered part at the edge part, the groove width is based on the intersection of the tread surface and the extension line of the groove wall in a cross-sectional view in which the groove length direction is a normal direction. Measured. In the configuration in which the groove extends in a zigzag shape or a wave shape in the tire circumferential direction, the groove width is measured with reference to the center line of the amplitude of the groove wall.

  The groove depth is measured as the maximum value of the distance from the tread surface to the groove bottom in an unloaded state in which the tire is mounted on the specified rim and filled with the specified internal pressure. Moreover, in the structure which a groove | channel has a partial uneven | corrugated | grooved part and a sipe in a groove bottom, groove depth is measured except these.

  The specified rim refers to an “applied rim” defined in JATMA, a “Design Rim” defined in TRA, or a “Measuring Rim” defined in ETRTO. The specified internal pressure means “maximum air pressure” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The specified load means the “maximum load capacity” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO. However, in JATMA, in the case of tires for passenger cars, the specified internal pressure is air pressure 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

  For example, in the configuration of FIG. 2, four circumferential main grooves 21 and 22 having a straight shape are arranged symmetrically about the tire equatorial plane CL. Further, five rows of land portions 31 to 33 are partitioned by the four circumferential main grooves 21 and 22. The land portion 31 is disposed on the tire equator plane CL. Moreover, each land part 31-33 is provided with the several lug groove | channels 41-43 which are arrange | positioned at predetermined intervals in the tire circumferential direction, and penetrate the land parts 31-33 in a tire width direction. Further, the second land portion 32 includes a circumferential narrow groove 23 that extends while being bent in the tire circumferential direction. And each land part 31-33 is divided into the circumferential direction main grooves 21 and 22, the circumferential direction fine groove 23, and the lug grooves 41-43, and becomes a block row | line | column.

  In the configuration of FIG. 2, as described above, the circumferential main grooves 21 and 22 have a straight shape. However, the present invention is not limited to this, and the circumferential main grooves 21 and 22 may have a zigzag shape or a wavy shape extending while being bent or curved in the tire circumferential direction (not shown).

  In the configuration of FIG. 2, as described above, the land portions 31 to 33 are divided in the tire circumferential direction by the lug grooves 41 to 43 to form a block row. However, the present invention is not limited to this, for example, by having a semi-closed structure in which the lug grooves 41 to 43 terminate in the land portions 31 to 33, so that the land portions 31 to 33 are ribs continuous in the tire circumferential direction. Good (not shown).

  Further, in the configuration of FIG. 2, the pneumatic tire 1 has a tread pattern that is symmetrical with respect to left and right points. However, the present invention is not limited to this, and the pneumatic tire 1 may have, for example, a tread pattern that is symmetrical to the left and right lines, a tread pattern that is asymmetrical to the left and right, and a tread pattern that has directionality in the tire rotation direction (not shown).

  In the configuration of FIG. 2, as described above, the pneumatic tire 1 includes four circumferential main grooves 21 and 22, and five rows of land portions 31 to 33 partitioned by these circumferential main grooves. It has. However, the present invention is not limited to this, and the pneumatic tire 1 may include three circumferential main grooves and four rows of land portions, or five or more circumferential main grooves and six rows or more of land portions. May be provided (not shown).

  In the tread pattern including the circumferential main grooves 21 and 22, the land portions 31 (see FIG. 2) on the tire equator plane CL or the left and right land divided into the circumferential main grooves on the tire equator plane CL. The part (not shown) is called the center land part. Also, the land portions 32, 32 on the inner side in the tire width direction defined by the left and right circumferential main grooves 22, 22 on the outermost side in the tire width direction are called second land portions, and the land portion 33 on the outer side in the tire width direction is the shoulder. Called the land.

  In the configuration of FIG. 2, as described above, the pneumatic tire 1 includes the circumferential main grooves 21 and 22 extending in the tire circumferential direction. However, the present invention is not limited thereto, and the pneumatic tire 1 may include a plurality of inclined main grooves that extend while being inclined at a predetermined angle with respect to the tire circumferential direction, instead of the circumferential main grooves 21 and 22. For example, the pneumatic tire 1 has a V-shape that is convex in the tire circumferential direction, and extends in the tire width direction and opens to the left and right tread ends, and adjacent V-shaped slopes. You may provide the several lug groove which connects a main groove, and the several land part divided by these V-shaped inclination main grooves and lug grooves (illustration omitted).

[Indication of vehicle mounting direction]
The pneumatic tire 1 has a mounting direction display unit (not shown) that indicates a mounting direction with respect to the vehicle. The mounting direction display part is configured by, for example, marks or irregularities attached to the sidewall part of the tire. For example, ECER30 (European Economic Commission Regulation Article 30) obligates the installation of a mounting direction display section on the side wall that is on the outer side in the vehicle width direction when the vehicle is mounted. In this embodiment, for the sake of convenience, the region located on the outer side in the vehicle width direction when the tire is mounted on the vehicle is referred to as the “outer region in the vehicle width direction”, and the region located on the inner side in the vehicle width direction is referred to as the “vehicle width. This is referred to as a “direction inner region”.

[Block sipe]
FIG. 3 is an explanatory diagram illustrating a land portion of the pneumatic tire illustrated in FIG. 2. This figure shows a plan view of one block 5 constituting the shoulder land portion 33 in the outer region in the vehicle width direction.

  As shown in FIGS. 2 and 3, in the pneumatic tire 1, the blocks 5 of all the land portions 31 to 33 each have a plurality of sipes 6. With these sipes 6, the edge components of the land portions 31 to 33 are increased, and the braking performance on ice and the performance on snow are improved.

  A sipe is an incision formed in a land portion, and generally has a sipe width of less than 1.0 [mm] and a sipe depth of 2.0 [mm] or more, so that the sipe is closed at the time of tire contact. The upper limit of the sipe depth is not particularly limited, but is generally shallower than the groove depth of the main groove.

  The sipe width is measured as the maximum value of the sipe opening width on the ground contact surface of the land portion in a no-load state in which a tire is mounted on a specified rim and filled with a specified internal pressure.

  The sipe 6 has a closed structure that terminates in the land portions 31 to 33 at both ends, opens to the edge portion of the block 5 at one end portion, and terminates in the block 5 at the other end portion. It may have either a semi-closed structure that opens or an open structure that opens at the edge of the block 5 at both ends. Moreover, the length, the number, and the arrangement structure of the sipes 6 in the land portions 31 to 33 can be appropriately selected within a range obvious to those skilled in the art. Further, the sipe 6 can extend in any direction of the tire width direction, the tire circumferential direction, and the direction inclined to these.

  For example, in the configuration of FIG. 3, the shoulder land portion 33 includes a plurality of blocks 5 that are partitioned into an outermost circumferential main groove 22 and a plurality of lug grooves 43 (see FIG. 2). One block 5 includes a plurality of sipes 6. These sipes 6 have a zigzag shape extending in the tire width direction, and are arranged in parallel at a predetermined interval in the tire circumferential direction. Further, the sipe 6 on the outermost side in the tire circumferential direction has a closed structure that terminates inside the block 5 at both ends. Thereby, the rigidity of the edge part of the step-on side and kick-out side of the block 5 at the time of tire rolling is ensured. Further, the sipe 6 at the center in the tire circumferential direction has a semi-closed structure that opens into the circumferential main groove 22 at one end and terminates inside the block 5 at the other end. . Thereby, the rigidity of the center part of the block 5 is reduced, and the rigidity distribution in the tire circumferential direction of the block is made uniform.

[Narrow shallow groove in the block]
FIG. 4 is an enlarged view showing a main part of the block shown in FIG. FIG. 5 is a cross-sectional view taken along line AA of the ground contact surface of the block illustrated in FIG. 4. In these drawings, FIG. 4 shows the positional relationship between the sipe 6, the thin shallow groove 7 and the concave portion 8, and FIG. 5 shows a sectional view of the thin shallow groove 7 and the concave portion 8 in the depth direction.

  In this pneumatic tire 1, the land portions 31 to 33 include a plurality of narrow grooves 7 on the ground contact surface (see FIG. 3). In such a configuration, the on-ice braking performance of the tire is improved by the thin shallow grooves 7 sucking and removing the water film interposed between the ice road surface and the tread surface when the tire is in contact with the tire.

  The thin shallow groove 7 has a groove width of 0.2 [mm] or more and 0.7 [mm] or less and a groove depth Hg (see FIG. 5) of 0.2 [mm] or more and 0.7 [mm] or less. . For this reason, the narrow shallow groove 7 is shallower than the sipe 6. A plurality of thin shallow grooves 7 are arranged on the entire surface of the land portions 31 to 33.

  For example, in the configuration of FIG. 3, the plurality of shallow grooves 7 are arranged over the entire ground contact surface of the shoulder land portion 33. Further, the thin shallow groove 7 has a linear shape, and is disposed at a predetermined inclination angle θ (see FIG. 4) with respect to the tire circumferential direction. A plurality of shallow grooves 7 are arranged in parallel with a predetermined interval P (see FIG. 4) between each other. As shown in FIG. 4, the thin shallow groove 7 intersects with the sipe 6 and is divided by the sipe 6 in the longitudinal direction.

  As shown in FIG. 3, in the configuration in which the plurality of shallow grooves 7 have a long shape and are arranged in parallel to each other, the inclination angle θ of the shallow grooves 7 (see FIG. 4) is 20 [deg. ] ≦ θ ≦ 80 [deg], preferably 40 [deg] ≦ θ ≦ 60 [deg]. The arrangement interval P (see FIG. 4) of the thin shallow grooves 7 is preferably in the range of 0.5 [mm] ≦ P ≦ 1.5 [mm], and 0.7 [mm] ≦ P ≦ 1. More preferably, it is in the range of 2 [mm]. Thereby, the water film removal effect | action by the thin shallow groove | channel 7 is ensured appropriately, and the ground-contact area of the land parts 31-33 is ensured. The arrangement density of the narrow shallow grooves 7 is not particularly limited, but is limited by the arrangement interval P described above.

  The arrangement interval P of the thin shallow grooves 7 is defined as the distance between the groove center lines of the adjacent thin shallow grooves 7 and 7.

[Block recess]
As shown in FIGS. 2 and 3, in the pneumatic tire 1, all the land portions 31 to 33 include a plurality of concave portions 8 on the ground contact surface. In such a configuration, when the tire is in contact with the tire, the concave portion 8 absorbs a water film formed between the ice road surface and the tread surface, and the edge component of the land portions 31 to 33 is increased by the concave portion 8 so that the braking performance on the ice of the tire is increased. Will improve.

  The concave portion 8 is a closed depression formed on the ground contact surface of the land portions 31 to 33 (a recess that does not open at the boundary of the ground contact surface, so-called dimple). Has a geometric shape. For example, the concave portion 8 may have a polygonal shape such as a circular shape, an elliptical shape, a rectangular shape, or a hexagonal shape. The circular or elliptical concave portion 8 is preferable in that the uneven wear of the ground contact surfaces of the land portions 31 to 33 is small, and the polygonal concave portion 8 is preferable in that the edge component is large and the braking performance on ice can be improved.

  Moreover, it is preferable that the opening area of the recessed part 8 exists in the range of 2.5 [mm ^ 2] or more and 10 [mm ^ 2] or less. For example, in the case of the circular concave portion 8, the diameter is in the range of about 1.8 [mm] to 3.6 [mm]. Thereby, the water film removal performance of the recessed part 8 is ensured.

  The opening area of the recessed portion 8 is an opening area of the recessed portion 8 on the ground contact surface of the land portions 31 to 33, and is measured as an unloaded state while attaching a tire to a specified rim and applying a specified internal pressure.

  The depth Hd of the recess 8 (see FIG. 5) and the groove depth Hg of the thin shallow groove 7 preferably have a relationship of 0.5 ≦ Hd / Hg ≦ 1.5, and 0.8 ≦ It is more preferable to have a relationship of Hd / Hg ≦ 1.2. That is, the depth Hd of the recess 8 and the groove depth Hg of the thin shallow groove 7 are substantially the same. Thereby, the water absorption effect | action of the ground surface of the land parts 31-33 improves. Moreover, since the recessed part 8 is shallow compared with a sipe (for example, the linear sipe 6 or a circular sipe (not shown)), the rigidity of the land parts 31 to 33 is ensured appropriately. Thereby, the braking performance on ice of the tire is ensured.

  The wall angle α (see FIG. 5) of the recess 8 is preferably in the range of −85 [deg] ≦ α ≦ 95 [deg]. That is, it is preferable that the inner wall of the recess 8 is substantially perpendicular to the ground contact surfaces of the land portions 31 to 33. Thereby, the edge component of the recessed part 8 increases.

  The wall angle α of the concave portion 8 is measured as an angle formed by the ground contact surfaces of the land portions 31 to 33 and the inner wall of the concave portion 8 in a sectional view of the concave portion 8 in the depth direction.

  In addition, as shown in FIG. 4, the recess 8 is disposed away from the sipe 6. That is, the recessed part 8 and the sipe 6 are arrange | positioned in a mutually different position on the ground surface of the land parts 31-33, and do not cross | intersect. The distance g between the recess 8 and the sipe 6 is preferably in the range of 0.2 [mm] ≦ g, and more preferably in the range of 0.3 [mm] ≦ g. Thereby, the rigidity of land part 31-33 is ensured appropriately.

  In addition, as shown in FIG. 4, the recess 8 is disposed so as to intersect the thin shallow groove 7 and communicate with the thin shallow groove 7. Moreover, the recessed part 8 is arrange | positioned ranging over several adjacent thin shallow grooves 7 and 7 isolate | separated mutually. In other words, a plurality of adjacent thin shallow grooves 7, 7 separated from each other are disposed through one recess 8. Thereby, a plurality of adjacent thin shallow grooves 7 and 7 are connected via the recess 8 and communicate with each other. Further, the concave portion 8 is interposed between the plurality of adjacent thin shallow grooves 7 and 7 to partially enlarge the volume of the thin shallow groove 7. Then, when the tire is in contact with the tire, the concave portion 8 becomes a pool of water, and the water film on the ice road surface is efficiently absorbed. Thereby, the braking performance on ice of a tire improves.

  The plurality of shallow grooves 7 separated from each other refers to a plurality of shallow grooves 7 extending without intersecting each other in an arrangement pattern of only the shallow grooves 7 excluding the sipes 6 and the recesses 8. Accordingly, an arrangement pattern in which the plurality of thin shallow grooves 7 intersect each other is excluded.

  For example, in the configuration of FIG. 3, the plurality of thin shallow grooves 7 having a linear shape are disposed on the entire surface of the land portion 33 at predetermined intervals while being inclined at a predetermined angle with respect to the tire circumferential direction. For this reason, as shown in FIG. 4, the adjacent thin shallow grooves 7 and 7 are arranged in parallel with each other and run in one direction. Moreover, the recessed part 8 is arrange | positioned ranging over two adjacent thin shallow grooves 7 and 7, and these thin shallow grooves 7 and 7 are connected. In other words, the two thin shallow grooves 7 and 7 that run side by side pass through one recess 8 in one direction. Not limited to the above, three or more shallow grooves 7 may penetrate one recess 8 (not shown).

  Further, in the above configuration, the number of the concave portions 8 arranged across the plurality of adjacent thin shallow grooves 7 on the grounding surface of one block 5 is based on the total number of the concave portions 8 on the grounding surface. It is preferably 70% or more, more preferably 80% or more. Thereby, the function as a water pool of the above-mentioned recessed part 8 is exhibited effectively. For example, in the configuration of FIG. 3, all the recesses 8 are disposed across two adjacent thin shallow grooves 7, 7. However, the present invention is not limited to this, and some of the recesses 8 may intersect with the single narrow groove 7 or between the adjacent shallow grooves 7 and 7 without intersecting the shallow groove 7. (Not shown).

  In the configuration of FIG. 3, the land portion 33 includes a plurality of sipes 6 that divide the narrow shallow grooves 7 on the ground contact surface. Further, a portion of one narrow shallow groove 7 defined by the sipe 6 extends without penetrating the plurality of recesses 8. That is, the plurality of recesses 8 are distributed and arranged so as not to be overlapped with respect to the portion of the single shallow groove 7 partitioned by the sipe 6. For this reason, only one concave portion 8 is arranged at the maximum in one narrow groove 7 portion.

  Further, as shown in FIG. 3, the recesses 8 are arranged sparsely compared to the narrow shallow grooves 7. Specifically, the arrangement density Da of the recesses 8 in the entire area of the ground contact surface of one rib or block is in the range of 0.8 [pieces / cm ^ 2] ≦ Da ≦ 4.0 [pieces / cm ^ 2]. It is preferable to be in the range of 1.0 [pieces / cm ^ 2] ≦ Da ≦ 3.0 [pieces / cm ^ 2]. Thereby, the arrangement density Da of the recessed portions 8 in one block or one rib is optimized.

  The arrangement density Da of the recesses 8 is defined as the total number of the recesses 8 with respect to the area of the ground contact surface of one rib or block. For example, when the land portion is a rib that is continuous in the tire circumferential direction (not shown), the total number of recesses 8 with respect to the contact area of the entire one rib is the arrangement density Da. When the land portion is a block (see FIGS. 2 and 3), the total number of the recesses 8 with respect to the ground contact area of one block 5 is the arrangement density Da.

  The contact area of the land is determined by the tire and the flat plate when the tire is mounted on the specified rim and applied with the specified internal pressure, and is placed perpendicular to the flat plate in a stationary state and applied with a load corresponding to the specified load. Measured at the contact surface.

  In the configuration of FIG. 3, the block 5 of the shoulder land portion 33 has a rectangular grounding surface. A plurality of sipes 6 are arranged in parallel in the tire circumferential direction to partition the block 5 into a plurality of sections in the tire circumferential direction. All sections have at least one recess 8. Further, at the central portion of the block 5 in the tire circumferential direction, a section having the recess 8 at the end on the circumferential main groove 22 side of the block 5 and a section having no recess 8 at the end are in the tire circumferential direction. Are alternately arranged. Further, in the sections of both end portions of the block 5 in the tire circumferential direction, the concave portions 8 are respectively disposed at corner portions of the block 5 on the circumferential main groove 22 side. Moreover, the recessed part 8 is not arrange | positioned in the center part area | region of the tire width direction in the area of the both ends of the tire circumferential direction of the block 5 (it arrange | positions only at the corner | angular part).

  The central region of the land portions 31 to 33 is defined as a region of the central portion 50 [%] in the tire width direction of the continuous contact surface of the land portions 31 to 33. Moreover, the edge part area | region of the land parts 31-33 is defined as each area | region of the edge part 25 [%] of the left-right direction of the tire width direction of the continuous contact surface of the land parts 31-33. Further, the central region and the end region are defined excluding a partial cutout portion 311 (see FIG. 7 described later) formed in the land portions 31 to 33. Further, for example, when the land portion is a rib that is continuous in the tire circumferential direction (not shown), a central region and an end region are defined for the ground contact surface of one entire rib. When the land portion is a block (see FIG. 2 and FIG. 3), a center region and an end region are defined for the ground plane of one block 5. Moreover, if the center of the recessed part 8 exists in said center part area | region or edge part area | region, it can be said that the recessed part 8 is arrange | positioned in said center part area | region or edge part area | region.

  The contact surface between the tire and the flat plate is applied when a load corresponding to the specified load is applied by placing the tire on a specified rim and applying a specified internal pressure while placing the tire in a stationary state perpendicular to the flat plate. Defined in terms of surfaces.

  A continuous ground plane is defined as a ground plane defined by grooves having a groove width of 2.0 [mm] or more and a groove depth of 3.0 [mm] or more. Specifically, the ground contact surface of one rib or one block defined by the circumferential groove and the lug groove having the groove width and the groove depth corresponds to the continuous ground contact surface. Also, for example, a closed structure lug groove that terminates in the land part, a partial notch formed in the land part (for example, a notch part 311 in FIG. 7 described later), a sipe or kerf that closes when the tire touches, It does not correspond to the above groove because it does not divide the ground contact surface.

  The corner portions of the land portions 31 to 33 are defined as 5 [mm] square regions including the corner portions of the land contact surface. The corner portion of the land portion includes not only the land portion defined by the main groove and the lug groove but also the land portion defined by the notch formed in the land portion. Moreover, if the center of the recessed part 8 exists in said corner | angular part, it can be said that the recessed part 8 is arrange | positioned in said corner | angular part.

  Further, in the configuration of FIG. 3, any three sections adjacent in the tire circumferential direction include a section having a recess 8 in an end region in the tire width direction, and a section having a recess 8 in a central region in the tire width direction. Each. Thereby, the recessed part 8 is disperse | distributed and arrange | positioned at the edge part area | region and center part area | region of the land parts 31-33.

  The sections of both ends of the block 5 in the tire circumferential direction refer to a pair of sections positioned at both ends of the tire circumferential direction among the plurality of sections of the block 5 partitioned by the plurality of sipes 6 in the tire circumferential direction. Moreover, the section of the center part of the tire circumferential direction of the block 5 means the area except the section of the both ends of the said tire circumferential direction.

  In the end region in the tire width direction of the block 5, particularly in the end region on the circumferential main groove 22 side, a larger contact pressure than the central portion of the block 5 acts when the tire contacts the ground. For this reason, when traveling on an icy road surface, the ice on the road surface is easily melted by the contact pressure, and a water film is easily generated. Accordingly, the concave portions 8 are disposed in the end region and the corner portion of the block 5, so that the water film on the ice road surface is efficiently absorbed, and the braking performance on ice of the tire is improved.

  In the configuration of FIG. 3, the sipe 6 is disposed parallel to or slightly inclined from the lug groove 43, and is disposed only in a region inside the tire width direction from the tire ground contact end T. Further, the narrow shallow groove 7 extends beyond the tire ground contact end T to a region outside the land portion 33 in the tire width direction. Further, the concave portion 8 is disposed only in a region on the inner side in the tire width direction from the tire ground contact end T.

  The tire ground contact edge T is the contact between the tire and the flat plate when a load corresponding to the predetermined load is applied by attaching the tire to the specified rim and applying the specified internal pressure and placing the tire perpendicularly to the flat plate in a stationary state. The maximum width position in the tire axial direction on the surface.

  6 and 7 are explanatory views showing a land portion of the pneumatic tire shown in FIG. In these drawings, FIG. 6 shows a plan view of one block 5 constituting the second land portion 32 in the outer region in the vehicle width direction. FIG. 7 shows a plan view of one block 5 constituting the center land portion 31.

  In the configuration of FIG. 2, the second land portion 32 is divided in the tire width direction by one circumferential narrow groove 23, and further divided in the tire circumferential direction by a plurality of lug grooves 42, thereby dividing the plurality of blocks 5. ing. Further, a block 5 that is long in the tire circumferential direction is formed in a region on the inner side in the tire width direction of the second land portion 32, and a short block 5 is formed in a region on the outer side in the tire width direction.

  Moreover, as shown in FIG. 6, the block 5 on the outer side in the tire width direction of the second land portion 32 has a rectangular contact surface. A plurality of sipes 6 are arranged in parallel in the tire circumferential direction to partition the block 5 into a plurality of sections. All sections have a plurality of recesses 8. Moreover, in the center part of the tire circumferential direction of the block 5, the section which has the recessed part 8 in the edge part area | region of the tire width direction of the block 5 and the area which has the recessed part 8 only in the center part area | region of the tire width direction, Alternatingly arranged in the tire circumferential direction. In addition, the recesses 8 are disposed at the four corners of the block 5, respectively. Further, in the sections of both end portions of the block 5 in the tire circumferential direction, the concave portions 8 are not disposed in the central region in the tire width direction, but are disposed only in the corner portions.

  In general, in the land portion 32 having the short block 5, the rigidity of the block 5 is low. In particular, in the configuration in which the block 5 has a plurality of sipes 6, the tendency becomes remarkable, and the braking performance on ice of the tire tends to be lowered. Therefore, in such a configuration, the block 5 has the recesses 8 in all the sections in the tire circumferential direction defined by the sipe 6, so that the water film on the ice road surface is efficiently absorbed, and the braking performance on the ice of the tire is improved. Secured.

  In the configuration of FIG. 2, the center land portion 31 is divided in the tire circumferential direction by a plurality of lug grooves 41, and a plurality of blocks 5 are partitioned. Further, the block 5 has a notch 311 on the extension line of the lug groove 42 of the second land portion 32. The block 5 has a rectangular grounding surface.

  Further, as shown in FIG. 7, a plurality of sipes 6 are arranged in parallel in the tire circumferential direction to partition the block 5 into a plurality of sections. Further, the block 5 has a section that does not have the recess 8. Further, any three adjacent sections include a section having no recess 8. For example, in the configuration of FIG. 7, sections having recesses 8 only at both ends in the tire width direction of the block 5 and sections having no recesses 8 are alternately arranged in the tire circumferential direction. In addition, the recesses 8 are disposed at the four corners of the block 5, respectively. Further, in the sections of both end portions of the block 5 in the tire circumferential direction, the concave portions 8 are not disposed in the central region in the tire width direction, but are disposed only in the corner portions. A section adjacent to the notch 311 has a recess 8.

  In general, the center land portion 31 preferably has high rigidity in order to ensure the steering stability performance of the tire. Therefore, as shown in FIG. 7, the block 5 of the center land portion 31 partially has a section that does not have the recess 8, whereby the rigidity of the block 5 is ensured and the steering stability performance of the tire is ensured.

  In the above configuration, it is preferable that at least a part of the recesses 8 is disposed at a position corresponding to a vent hole of a tire molding die (not shown). That is, in the tire vulcanization molding step, it is necessary to discharge the air in the tire molding die to the outside in order to press the green tire against the tire molding die. For this reason, the tire molding die has a plurality of vent devices (not shown) on the die surface for molding the ground contact surfaces of the land portions 31 to 33. Moreover, a certain kind of vent apparatus forms a vent trace (small hollow formed with the vent apparatus) in the ground surface of the land parts 31-33 after vulcanization molding. Therefore, by using this vent mark as the concave portion 8, the vent mark is used effectively, and unnecessary dents in the ground contact surfaces of the land portions 31 to 33 are reduced to reduce the ground contact area of the land portions 31 to 33. Properly secured.

[Opening area ratio of recesses]
In this pneumatic tire 1, the opening area ratio Sin of the recess 8 in the vehicle width direction inner region with the tire equatorial plane CL as a boundary, and the opening area ratio Sout of the recess 8 in the vehicle width direction outer region satisfy Sin <Sout. Have a relationship. That is, the opening area ratio Sout of the recess 8 in the vehicle width direction outer region is larger than that in the vehicle width direction inner region. In addition, the ratio Sout / Sin of the opening area ratio of the recess 8 preferably has a relationship of 1.10 ≦ Sout / Sin, and more preferably has a relationship of 1.20 ≦ Sout / Sin. The upper limit of the ratio Sout / Sin is not particularly limited, but is limited by the relationship between the arrangement density of the recesses 8 and the opening area. Further, when all the concave portions 8 are arranged in the vehicle width direction outer region, that is, when the concave portions 8 are arranged only in the vehicle width direction outer region and not arranged in the vehicle width direction inner region, Sin = 0. , Sin <Sout is satisfied.

  The opening area ratio of the recess is defined as a ratio between the sum of the opening areas of the recesses arranged in the predetermined region and the ground contact area of the region. When the concave portion and the boundary line of the region intersect, it can be said that the concave portion is arranged in the region if the central point of the concave portion is in the region.

  The opening area of the recess and the contact area of the area are determined when the tire is mounted on the specified rim and applied with the specified internal pressure, and is placed perpendicular to the flat plate in a stationary state and applied with a load corresponding to the specified load. It is measured at the contact surface between the tire and the flat plate.

  The opening area ratios Sin and Sout of the recesses 8 in the vehicle width direction inner region and the vehicle width direction outer region can be adjusted by the arrangement density of the recesses 8 in each region. That is, the concave portions 8 are densely arranged in the outer region in the vehicle width direction and sparsely arranged in the inner region in the vehicle width direction, whereby the opening area ratio Sout of the concave portion 8 in the outer region in the vehicle width direction is set large.

  Moreover, as shown in FIG. 2, it is preferable that the recessed part 8 is disperse | distributed and arrange | positioned to the whole region of the grounding area | region of a tread part. Thereby, the fundamental effect of the single recessed part 8 is obtained in the whole tread. However, the present invention is not limited to this, and the recess 8 may be disposed only in the outer region in the vehicle width direction (not shown).

  Specifically, as shown in FIG. 2, the arrangement density Din of the recesses 8 in the inner region in the vehicle width direction and the arrangement density Dout of the recesses 8 in the outer region in the vehicle width direction have a relationship of Din <Dout. The condition Sin <Sout of the opening area ratio of the recess 8 is satisfied. That is, the concave portions 8 are densely arranged in the outer region in the vehicle width direction and are sparsely arranged in the inner region in the vehicle width direction. Further, the arrangement density Dout of the recesses 8 in the outer region in the vehicle width direction is higher than the arrangement density Dtr of the recesses 8 in the entire tread portion (Dtr <Dout).

  Further, the ratio Dout / Din is preferably in the range of 1.10 ≦ Dout / Din, and more preferably in the range of 1.20 ≦ Dout / Din. The upper limit of the ratio Dout / Din is not particularly limited, but is limited by the range of the arrangement density Da of the concave portions 8 on the continuous ground contact surface of the land portions 31 to 33 described above. When all the concave portions 8 are disposed in the vehicle width direction outer region (not shown), Din = 0, and the conditions of Sin <Sout and Din <Dout are satisfied.

  The arrangement density Din, Dout of the recesses 8 is defined as a ratio between the total number of the recesses 8 arranged in each region of the tread portion (the vehicle width direction outer region and the vehicle width direction inner region) and the ground contact area of each region. The

  Further, the number of the recessed portions 8 is counted as the number of the center points of the recessed portions 8 in the predetermined area. In addition, when the recess and the boundary line of the region intersect, it can be said that the recess is disposed in the region if the center point of the recess is in the region.

  The contact area of the tread portion is defined as an area between the left and right tire contact ends T, T. The tire ground contact end T is a contact surface between the tire and the flat plate when a tire is mounted on a predetermined rim to apply a predetermined internal pressure and a load corresponding to the predetermined load is applied in a stationary state perpendicular to the flat plate. Is defined as the maximum width position in the tire axial direction.

  When the tire is mounted on a vehicle having a negative camber, the contact pressure in the outer region in the vehicle width direction of the tire is relatively low. At this time, since the recesses 8 are densely arranged in the outer region in the vehicle width direction, the contact area of the outer region in the vehicle width direction is reduced, the contact pressure is increased, and the snow column shearing force (digging force) by the recess 8 is increased. To increase. Thereby, the traction performance of the tire is improved, and the performance on snow of the tire is improved.

  In the configuration of FIG. 2, as described above, the pneumatic tire 1 includes the four circumferential main grooves 21 and 22 and the five rows of land portions 31 to 33. Further, these circumferential main grooves 21 and 22 are arranged symmetrically about the tire equatorial plane CL. The distance between the left and right outermost main grooves (the left and right circumferential main grooves on the outermost side in the tire width direction) 22 and 22 and the tire equatorial plane CL (dimension symbol omitted in the figure) is the tire ground contact width. 28 [%] to 38 [%].

  The distance between the tire equatorial plane CL and the outermost circumferential main groove 22 is the distance from the tire equatorial plane CL to the groove center line of the outermost circumferential main groove 22, and the tire is mounted on the prescribed rim to apply the prescribed internal pressure. And measured as a no-load condition.

  The tire ground contact width is the contact surface between the tire and the flat plate when the tire is mounted on the specified rim and applied with the specified internal pressure, and the load corresponding to the specified load is applied in a stationary state perpendicular to the flat plate. It is measured as the maximum linear distance in the tire axial direction.

  Further, in the configuration having four or more circumferential main grooves 21 and 22 as shown in FIG. 2, the opening area ratio S1 of the concave portion 8 in the center land portion 31 and the left and right regions with the tire equator plane CL as a boundary It is preferable that the opening area ratio S2 of the concave portion 8 in the second land portion 32 and the opening area ratio S3 of the concave portion 8 in the shoulder land portion 33 have a relationship of S1 <S3 <S2. That is, the opening area ratio S2 of the recess 8 in the second land portion 32 is the highest compared to the opening area ratio S1 of the recess 8 in the center land portion 31 and the opening area ratio S3 of the recess 8 in the shoulder land portion 33 (S1 <S2 and S3 <S2). Moreover, the opening area ratio S3 of the recessed part 8 in the shoulder land part 33 is higher than the opening area ratio S1 of the recessed part 8 in the center land part 31 (S1 <S3). At the same time, the opening area ratio Sin of the recess 8 in the inner region in the vehicle width direction and the opening area ratio Sout of the recess 8 in the outer region in the vehicle width direction are set to a relationship of Sin <Sout. Thereby, the opening area ratio of the recessed part 8 in the grounding area | region of the whole tread is optimized.

  Moreover, in said structure, it is preferable that the opening area ratio S1 of the recessed part 8 in the center land part 31 and the opening area ratio S3 of the recessed part 8 in the shoulder land part 33 have a relationship of 1.10 <= S3 / S1, It is more preferable to have a relationship of 1.20 ≦ S3 / S1. The upper limit of the ratio S3 / S1 is not particularly limited, but is limited by the range of the arrangement density Da of the concave portions 8 on the continuous ground contact surface of the land portions 31 to 33 described above.

  The opening area ratio S3 of the recess 8 in the shoulder land portion 33 and the opening area ratio S2 of the recess 8 in the second land portion 32 preferably have a relationship of 1.10 ≦ S2 / S3, and 1.20 ≦ S2 / It is more preferable to have the relationship of S3.

  For example, in the configuration of FIG. 2, the placement density D1 of the recesses 8 in the center land portion 31, the placement density D2 of the recesses 8 in the second land portion 32, and the placement density D3 of the recesses 8 in the shoulder land portion 33 are D1 < It has a relationship of D3 <D2. Thereby, the arrangement density of the concave portions 8 in the ground contact region of the entire tread is optimized.

  In general, in the shoulder land portion 33, compared to the center land portion 31, the contact pressure is relatively high and a water film tends to be easily generated on the ice road surface. Accordingly, as shown in FIG. 2, the opening area ratio S3 of the recess 8 of the shoulder land portion 33 is set to be relatively higher than the opening area ratio S1 of the recess 8 of the center land portion 31 (S1 <S3). The water removal performance of the shoulder land portion 33 is efficiently enhanced, and the braking performance on ice of the tire is improved. Further, as described above, the opening area ratio Sout of the recess 8 in the outer region in the vehicle width direction is set to be relatively higher (Sin <Sout) than the opening area ratio Sin of the recess 8 in the inner region in the vehicle width direction. When the tire is mounted on a vehicle having a negative camber, the performance on the snow of the tire is improved. With these complementary actions, the braking performance on ice and the performance on snow of the tire are compatible.

  However, the present invention is not limited to this, and the opening area ratio S1 of the recess 8 of the center land portion 31 may be set to be relatively higher (S3 <S1) than the opening area ratio S3 of the recess 8 of the shoulder land portion 33 (illustrated). (Omitted). In general, the center land portion 31 has a relatively low ground pressure compared to the shoulder land portion 33. Therefore, by setting the opening area ratio S1 of the concave portion 8 of the center land portion 31 to be high, the ground contact area of the center land portion 31 decreases, the ground pressure increases, and the snow column shear force by the recess 8 increases. . Thereby, the traction performance of the tire is improved, and the performance on snow of the tire is improved. Further, as described above, the opening area ratio Sout of the recess 8 in the outer region in the vehicle width direction is set to be relatively higher (Sin <Sout) than the opening area ratio Sin of the recess 8 in the inner region in the vehicle width direction. When the tire is mounted on a vehicle having a negative camber, the performance on the snow of the tire is improved. These synergistic effects effectively improve the on-snow performance of the tire.

  In the configuration having the circumferential main groove on the tire equator plane CL (not shown), the left and right land portions defined by the circumferential main groove on the tire equator plane CL are the center land portions, and the above-described recess 8 The opening area ratio S1 is satisfied.

  In the configuration of FIG. 2, the second land portion 32 includes the circumferential narrow groove 23 extending in the tire circumferential direction as described above. Further, the circumferential narrow groove 23 is formed at the center of the second land portion 32 in the tire width direction (an area of 30 [%] to 70 [%] of the width of the second land portion 32 with respect to the outermost circumferential main groove 22). Has been placed. At this time, the opening area ratio S21 of the recess 8 in the inner region in the tire width direction of the second land portion 32 partitioned by the circumferential narrow groove 23 and the opening area ratio S22 of the recess 8 in the outer region in the tire width direction are: It is preferable to have a relationship of S21 <S22. Therefore, the concave portion 8 is set relatively high in the region on the outer side in the tire width direction of the second land portion 32. Specifically, the opening area ratios S21 and S22 of the recess 8 preferably have a relationship of 1.10 ≦ S22 / S21, and more preferably have a relationship of 1.20 ≦ S22 / S21.

[Modification]
8-14 is explanatory drawing which shows the modification of the pneumatic tire described in FIG. These drawings show the positional relationship between the sipe 6, the thin shallow groove 7, and the recess 8.

  In the configuration of FIG. 4, the narrow shallow grooves 7 are arranged to be inclined at a predetermined angle θ with respect to the tire circumferential direction. Such a configuration is preferable in that the inclined thin shallow grooves 7 cause edge components in both the tire circumferential direction and the tire width direction.

  However, the present invention is not limited to this, and the thin shallow groove 7 may extend in parallel to the tire circumferential direction (see FIG. 8) or may extend in parallel to the tire width direction (see FIG. 9).

  Moreover, in the structure of FIG. 4, the thin shallow groove 7 has a linear shape. Such a configuration is preferable in that the thin shallow groove 7 can be easily formed.

  However, the present invention is not limited to this, and the thin shallow groove 7 may have a zigzag shape (see FIG. 10) or a wavy shape (see FIG. 11). At this time, as shown in FIGS. 10 and 11, the plurality of thin shallow grooves 7 may be arranged with the phases aligned with each other, or may be arranged with the phases shifted from each other as shown in FIG. Moreover, as shown in FIG. 13, the thin shallow groove 7 may have a short structure that is bent or curved. At this time, the short thin shallow grooves 7 may be arranged while being offset from each other (see FIG. 13), or may be arranged in a matrix (not shown). Further, the thin shallow groove 7 may have an arc shape (see FIG. 14), or may have a curved shape such as an S shape (not shown).

  10 to 14, similarly to the configurations of FIGS. 4, 8, and 9, the thin shallow groove 7 may be inclined at a predetermined angle θ with respect to the tire circumferential direction, or in the tire circumferential direction. May extend parallel to the tire width or may extend parallel to the tire width direction. When the thin shallow groove 7 has a zigzag shape or a wavy shape, the inclination angle θ of the thin shallow groove 7 is measured with reference to the center of the amplitude of the zigzag shape or the wavy shape.

  15 and 16 are explanatory views showing a modification of the pneumatic tire shown in FIG. These drawings show the positional relationship between the sipe 6, the thin shallow groove 7, and the recess 8.

  In the configuration of FIG. 4, the thin shallow groove 7 has a linear structure extending in a predetermined direction. Such a configuration is preferable in that the thin shallow groove 7 can extend continuously over the entire area of the ground contact surface of the block 5.

  However, the present invention is not limited to this, and as shown in FIGS. 15 and 16, the thin shallow grooves 7 may have an annular structure and be arranged at a predetermined interval from each other. For example, the thin shallow groove 7 may have a polygonal shape (not shown) such as a circular shape (FIG. 15), an elliptical shape (not shown), a rectangular shape (FIG. 16), a triangular shape, a hexagonal shape, or the like. Also in such a configuration, the concave portion 8 is disposed across a plurality of adjacent thin shallow grooves 7 and 7 separated from each other.

  FIG. 17 is an explanatory diagram showing a modification of the pneumatic tire depicted in FIG. This figure shows a cross-sectional view in the depth direction of the narrow shallow grooves 7a and 7b and the recess 8.

  In the configuration of FIG. 5, all the thin shallow grooves 7 have the same groove depth Hg.

  On the other hand, in the configuration of FIG. 17, the groove depth of a part of the shallow grooves 7b is set to be shallower than the groove depth Hg of the reference shallow groove 7a. In such a configuration, the thin shallow groove 7b having the shallow groove depth disappears first and the thin shallow groove 7a having the deep groove depth Hg disappears after the tire wear progresses. Thereby, the property change of the block 5 by all the thin shallow grooves 7 disappearing simultaneously can be suppressed.

  18-21 is explanatory drawing which shows the modification of the pneumatic tire described in FIG. These drawings show the positional relationship between the sipe 6, the thin shallow groove 7, and the recess 8.

  In the configuration of FIG. 4, all the narrow grooves 7 are arranged in parallel to each other. For this reason, the thin shallow grooves 7 are arranged in a stripe shape without crossing each other.

  However, the present invention is not limited to this, and as shown in FIGS. 18 to 21, the thin shallow grooves 7 may be arranged so as to intersect or communicate with each other. For example, as shown in FIGS. 18 to 19, a plurality of narrow grooves 7 may be arranged in a mesh shape. At this time, the thin shallow grooves 7 may be arranged to be inclined with respect to the tire circumferential direction and the tire width direction (FIG. 18), or may be arranged in parallel to the tire circumferential direction and the tire width direction. (FIG. 19). Further, some of the thin shallow grooves 7b may be arranged curved, for example, in an arc shape or a wave shape (FIG. 20). Further, the narrow shallow grooves 7 may have an annular structure and be arranged in communication with each other (FIG. 21). For example, in the configuration of FIG. 21, the thin shallow grooves 7 are arranged in a honeycomb shape. Moreover, also in these structures, the recessed part 8 is arrange | positioned crossing the 2 or more thin shallow groove | channel 7 which does not cross | intersect mutually.

[Modification 2]
22 and 23 are explanatory views showing modifications of the pneumatic tire depicted in FIG. In these drawings, FIG. 22 shows a plan view of the entire tread portion, and FIG. 23 shows a plan view of the center land portion 31 and the left and right second land portions 32 and 32.

  In the configuration of FIG. 2, as described above, the arrangement density Din of the recesses 8 in the inner region in the vehicle width direction and the arrangement density Dout of the recesses 8 in the outer region in the vehicle width direction have a relationship of Din <Dout. The condition Sin <Sout for the opening area ratio of the recess 8 is satisfied. Specifically, as shown in FIG. 2, the concave portions 8 are densely arranged in the shoulder land portion 33 and the second land portion 32 in the outer region in the vehicle width direction, thereby arranging the concave portions 8 in the outer region in the vehicle width direction. Dout is set high. Moreover, the recessed part 8 of each land part 31-33 has the same opening shape and the same opening area.

  On the other hand, in the configuration of FIG. 22, the average value Ain of the opening area of the recess 8 in the inner region in the vehicle width direction of the tread portion and the average value Aout of the opening area of the recess 8 in the outer region in the vehicle width direction are Ain. By satisfying the relationship <Aout, the condition Sin <Sout of the opening area ratio of the recess 8 is satisfied. That is, a plurality of types of recesses 8 having different opening areas are used, the recesses 8 having a large opening area are arranged in the outer region in the vehicle width direction, and conversely, the recesses 8 having a small opening area are arranged in the vehicle width direction inner side. Placed in the area. Further, the ratio Aout / Ain of the average values Ain and Aout of the recesses 8 preferably has a relationship of 1.10 ≦ Aout / Ain, and more preferably has a relationship of 1.20 ≦ Aout / Ain. . The upper limit of the ratio Aout / Ain is not particularly limited, but is restricted by the relationship between the arrangement density of the recesses 8 and the opening area. When all the concave portions 8 are arranged in the vehicle width direction outer region, Ain = 0, and the conditions of Ain <Aout and Sin <Sout are satisfied.

  The average values Ain and Aout of the opening area are respectively defined as ratios of the sum of the opening areas of the recesses and the total number of the recesses in each region (the vehicle width direction inner region and the vehicle width direction outer region) of the tread portion.

  Generally, when a tire is mounted on a vehicle having a negative camber, the contact pressure in the outer region in the vehicle width direction of the tire is relatively low. At this time, since the concave portion 8 having a relatively large opening area is disposed in the vehicle width direction outer region having a relatively low contact pressure, the contact area of the vehicle width direction outer region is reduced, and the contact pressure is increased. The snow column shear force (digging force) due to the recess 8 increases. Thereby, the traction performance of the tire is improved, and the performance on snow of the tire is improved.

  Further, in the configuration of FIG. 22, the plurality of concave portions 8 arranged in the land portions 31 to 33 have the same opening area. Further, as the whole tread, two types of large and small concave portions 8 having different opening areas are used, and all the concave portions 8 arranged on the second land portion 32 and the shoulder land portion 33 on the outer side in the vehicle width direction have a large opening area. All the concave portions 8 arranged in the second land portion 32 and the shoulder land portion 33 on the inner side in the vehicle width direction have a small opening area. For this reason, the opening area of the recessed part 8 arrange | positioned at the right-and-left 2nd land part 32 and the shoulder land part 33 is constant in either large or small.

  However, the present invention is not limited to this, and the plurality of recesses 8 arranged in one land portion may have different opening areas (not shown). In this case, 70 [%] or more of the recesses 8 disposed in the outer region in the vehicle width direction have an opening area larger than the average of the entire tread portion, and 70 [%] disposed in the inner region in the vehicle width direction. It is preferable that the above-mentioned recessed part 8 has an opening area smaller than the average of the whole tread part. Thereby, the function by the opening area ratio of the recessed part 8 of each area | region differing appropriately is ensured.

  In the configuration of FIG. 22, all the concave portions 8 arranged in the center land portion 31 have a relatively large opening area. Specifically, a plurality of concave portions 8 having a large opening area are arranged along the left and right edge portions of the center land portion 31, and the opening areas of the concave portions 8 arranged at the left and right edge portions are equal to each other. Such a configuration is preferable in that uneven wear between the left and right edge portions of the center land portion 31 can be suppressed.

  However, the present invention is not limited to this, and a relatively small concave portion 8 (for example, the concave portion 8 arranged in the shoulder land portion 33 in the inner region in the vehicle width direction in FIG. 22) may be arranged in the center land portion 31. The recesses 8 having different opening areas may be mixed and arranged (not shown).

  In the configuration of FIG. 22, the pneumatic tire 1 has a tread pattern that is point-symmetric in the left and right regions with the tire equatorial plane CL as a boundary. Moreover, the recessed part 8 is arrange | positioned point-symmetrically in the area | region on either side which makes tire equatorial plane CL a boundary. For this reason, the arrangement density of the tread portion center region and the shoulder region at the time of tire contact is substantially the same between the left and right regions of the tire, and the relationship Sin < Sout is adjusted. Such a configuration is preferable in that the relationship Sin <Sout between the opening area ratios of the left and right regions of the tire can be easily adjusted.

  However, the present invention is not limited to this. For example, the pneumatic tire 1 has a left-right asymmetric tread pattern with the tire equator plane CL as a boundary, so that the recess 8 is asymmetric in the left and right regions with the tire equator plane CL as a boundary. (Not shown).

  In the configuration of FIG. 22, the opening area ratio S <b> 1 of the recess 8 in the center land portion 31, the opening area ratio S <b> 2 of the recess 8 in the second land portion 32, and the recess in the shoulder land portion 33 in the vehicle width direction outer region. The opening area ratio S3 of 8 has a relationship of S1 <S3 <S2. In the second land portion 32 having the largest contribution to the tire driving performance and braking performance, the opening area ratio S2 of the recessed portion 8 is set large, so that the function of the recessed portion 8 is effectively exhibited. Further, since the opening area ratio of the recesses 8 in the center land portion 31 and the shoulder land portion 33 has the above relationship S1 <S3, the contact pressure is higher than that in the center land portion 31, and a water film is easily generated on the ice road surface. The water removal property of the shoulder land portion 33 is efficiently enhanced.

  However, the present invention is not limited to this. For example, when the relatively small concave portion 8 is disposed in the shoulder land portion 33 (not shown), the opening area ratio S1 of the concave portion 8 of the center land portion 31 is reduced. The opening area ratio S3 may be set relatively higher (S3 <S1).

  In the configuration of FIG. 22, the opening area ratio S <b> 21 of the recess 8 in the inner region in the tire width direction of the second land portion 32 partitioned by the circumferential narrow groove 23 in the left and right regions with the tire equatorial plane CL as a boundary. And the opening area ratio S22 of the recess 8 in the outer region in the tire width direction has a relationship of S21 <S22, respectively (see FIG. 23). As a result, a difference is formed in the grounding characteristics of the left and right block rows of the second land portion 32.

[effect]
As described above, the pneumatic tire 1 includes land portions 31 to 33 having ribs or a plurality of blocks on the tread surface (see FIG. 2). The pneumatic tire 1 includes a mounting direction display unit (not shown) that displays a mounting direction with respect to the vehicle. Further, the land portions 31 to 33 include a plurality of narrow grooves 7 and a plurality of recesses 8 on the grounding surface (see FIGS. 3 and 4). The opening area ratio Sin of the recess 8 in the vehicle width direction inner region with the tire equator plane CL as a boundary and the opening area ratio Sout of the recess 8 in the vehicle width direction outer region have a relationship of Sin <Sout.

  In this configuration, (1) since the land portions 31 to 33 include the shallow grooves 7 and the recesses 8 on the ground contact surface, the edge components of the land portions 31 to 33 are increased, and the on-ice braking performance of the tire is improved. is there. (2) When the tire is mounted on a vehicle having a negative camber, the contact pressure in the outer region in the vehicle width direction of the tire is relatively low. At this time, since the opening area ratio Sin of the recessed portion 8 in the inner region in the vehicle width direction is large, the contact area in the outer region in the vehicle width direction decreases, the contact pressure increases, and the snow column shear force (digging force) by the recessed portion 8 increases. Will increase. Thereby, there exists an advantage which the traction performance of a tire improves and the on-snow performance of a tire improves. Moreover, (3) Since the recessed part 8 is shallow compared with a sipe (for example, the linear sipe 6 or circular sipe (illustration omitted)), the rigidity of the land parts 31-33 is ensured appropriately. Thereby, there is an advantage that the braking performance on ice and the performance on snow of the tire are ensured.

  In this pneumatic tire 1, the opening area ratio Sin of the recess 8 in the inner region in the vehicle width direction and the opening area ratio Sout of the recess 8 in the outer region in the vehicle width direction satisfy the relationship of 1.10 ≦ Sout / Sin. Have. As a result, there is an advantage that the ratio Sout / Sin of the opening area ratio of the recess 8 in each region is ensured, and the action due to the uneven opening area of the recess 8 can be obtained appropriately.

  Further, in the pneumatic tire 1, the arrangement density Dout of the recesses 8 in the vehicle width direction outer region with the tire equatorial plane CL as a boundary and the arrangement density Din of the recesses 8 in the vehicle width direction inner region satisfy Din <Dout. Have a relationship. When the tire is mounted on a vehicle having a negative camber, the contact pressure in the outer region in the vehicle width direction of the tire is relatively low. At this time, since the recesses 8 are densely arranged in the outer region in the vehicle width direction, the contact area of the outer region in the vehicle width direction is reduced, the contact pressure is increased, and the snow column shearing force (digging force) by the recess 8 is increased. To increase. Thereby, there exists an advantage which the traction performance of a tire improves and the on-snow performance of a tire improves.

  In the pneumatic tire 1, the arrangement density Din of the recesses 8 in the inner region in the vehicle width direction and the arrangement density Dout of the recesses 8 in the outer region in the vehicle width direction have a relationship of 1.10 ≦ Dout / Din. Thereby, there exists an advantage by which ratio Dout / Din of the arrangement density of the recessed part 8 is optimized.

  In the pneumatic tire 1, the average value Ain of the opening area of the recess 8 in the inner region in the vehicle width direction and the average value Aout of the opening area of the recess 8 in the outer region in the vehicle width direction have a relationship of Ain <Aout. Have. (See FIGS. 22 and 23). When the tire is mounted on a vehicle having a negative camber, the contact pressure in the outer region in the vehicle width direction of the tire is relatively low. At this time, since the recessed portion 8 having a relatively large opening area is disposed in the outer region in the vehicle width direction, the contact area of the outer region in the vehicle width direction decreases, the contact pressure increases, and the snow column shear force by the recessed portion 8 increases. (Digging force) increases. Thereby, there exists an advantage which the traction performance of a tire improves and the on-snow performance of a tire improves.

  In this pneumatic tire 1, the average value Ain of the opening area of the recess 8 in the inner region in the vehicle width direction and the average value Aout of the opening area of the recess 8 in the outer region in the vehicle width direction are 1.10 ≦ Aout / Ain relationship. Thereby, there is an advantage that the ratio Aout / Ain of the opening area of the concave portion 8 in each region is ensured, and the action due to the deviation of the opening area of the concave portion 8 can be obtained appropriately.

  Further, in this pneumatic tire 1, the inner region in the vehicle width direction includes a plurality of types of recesses 8 (not shown) having mutually different opening areas, and is arranged in the inner region in the vehicle width direction 70 [%]. The above recessed part 8 has an opening area smaller than the average of the whole tread part. Thereby, there exists an advantage by which the effect | action by the deviation of the opening area of the recessed part 8 is obtained appropriately.

  Further, in this pneumatic tire 1, the outer region in the vehicle width direction includes a plurality of types of recesses 8 (not shown) having mutually different opening areas, and is arranged in the outer region in the vehicle width direction 70 [%]. The above recessed part 8 has an opening area larger than the average of the whole tread part. Thereby, the snow column shearing action of the recessed part 8 is ensured appropriately, and there exists an advantage which the traction performance of a tire improves.

  In addition, the pneumatic tire 1 includes four or more circumferential main grooves 21 and 22 and five or more rows of land portions 31 to 33 defined by the circumferential main grooves 21 and 22 (see FIG. 2). ). The distance between the left and right outermost main grooves 22 and 22 and the tire equatorial plane CL is in the range of 28 [%] to 38 [%] of the tire ground contact width. Further, the opening area ratio S1 of the recess 8 in the land portion 31 (see FIG. 2) on the tire equator plane CL or the land portion (not shown) partitioned in the circumferential main groove on the tire equator plane CL, The opening area ratio S2 of the concave portion 8 in the land portion 32 on the inner side in the tire width direction partitioned by the outer circumferential direction main groove 22 and the opening of the concave portion 8 in the land portion 33 on the outer side in the tire width direction partitioned by the outermost circumferential direction main groove 22. The area ratio S3 has a relationship of S1 <S2 and S3 <S2. In general, the second land portion 32 greatly contributes to the braking performance and driving performance of the tire. Therefore, by setting the opening area ratio S2 of the concave portion 8 in the second land portion 32 to be high, the water absorption action of the concave portion 8 is effectively exhibited, and the braking performance on ice of the tire is effectively improved. Thus, there is an advantage that the snow column shearing action of No. 8 is effectively exhibited and the performance of the tire on the snow is effectively improved. Moreover, the recessed part 8 is additionally provided in the second land part 32, and the arrangement | positioning number of the recessed part 8 of the whole tread increases, The shear action in snow of the recessed part 8 increases, There exists an advantage which the on-snow performance of a tire improves. .

  In addition, the pneumatic tire 1 includes four or more circumferential main grooves 21 and 22 and five or more rows of land portions 31 to 33 defined by the circumferential main grooves 21 and 22 (see FIG. 2). ). The distance between the left and right outermost main grooves 22 and 22 and the tire equatorial plane CL is in the range of 28 [%] to 38 [%] of the tire ground contact width. Further, the opening area ratio S1 of the recess 8 in the land portion 31 (see FIG. 2) on the tire equator plane CL or the land portion (not shown) partitioned in the circumferential main groove on the tire equator plane CL, The opening area ratio S3 of the recess 8 in the land portion 33 on the outer side in the tire width direction partitioned by the outer circumferential direction main groove 22 has a relationship of S1 <S3. In such a configuration, the water absorbing action of the recess 8 improves the water removal (water absorption) of the shoulder land portion 33 where the ground pressure is high and a water film is likely to be generated on the ice road surface. Thereby, there exists an advantage which the braking performance on ice of a tire improves effectively. Moreover, the recessed part 8 is added to the shoulder land part 33, and the arrangement | positioning number of the recessed part 8 of the whole tread increases, The shear action in the snow of the recessed part 8 increases, There exists an advantage which the on-snow performance of a tire improves. .

  The pneumatic tire 1 includes four or more circumferential main grooves 21 and 22 and five or more rows of land portions 31 to 33 defined by the circumferential main grooves 21 and 22 (see FIG. 2). The distance between the left and right outermost main grooves 22 and 22 and the tire equatorial plane CL is in the range of 28 [%] to 38 [%] of the tire ground contact width. In addition, a land portion (second land portion) 32 on the inner side in the tire width direction divided into the outermost circumferential main groove 22 includes a circumferential narrow groove 23 extending in the tire circumferential direction. Further, the opening area ratio S21 of the recess 8 in the inner region in the tire width direction of the second land portion 32 partitioned by the circumferential narrow groove 23 and the opening area ratio S22 of the recess 8 in the outer region in the tire width direction are S21 < It has the relationship of S22. In such a configuration, the recess 8 is set to be relatively high in the outer region in the tire width direction of the second land portion 32 and is set to be relatively low in the inner region in the tire width direction, so that the water removal performance in the second land portion 32 is achieved. There is an advantage that the braking performance on the ice of the tire is improved by improving both of the above and securing the contact area.

  Further, in this pneumatic tire 1, the arrangement density Da of the concave portions 8 on the continuous contact surface of the land portions 31 to 33 is 0.8 [piece / cm ^ 2] ≦ Da ≦ 4.0 [piece / cm ^ 2]. ]. Thereby, there exists an advantage by which arrangement | positioning density Da of the recessed part 8 in one block or one rib is optimized. That is, when 0.8 [pieces / cm ^ 2] ≦ Da, the number of the recessed portions 8 is ensured, and the water film removing action by the recessed portions 8 is appropriately ensured. In addition, since Da ≦ 4.0 [pieces / cm 2], the ground contact areas of the land portions 31 to 33 are appropriately secured.

  Moreover, in this pneumatic tire 1, the opening area of the recessed part 8 exists in the range of 2.5 [mm ^ 2] or more and 10 [mm ^ 2] or less. Thereby, there exists an advantage by which the opening area of the recessed part 8 is optimized. That is, when the opening area of the recess 8 is 2.5 [mm ^ 2] or more, the edge action and water absorption of the recess 8 are ensured. Moreover, when the opening area of the recessed part 8 is 10 [mm ^ 2] or less, the ground contact area and the rigidity of the land parts 31 to 33 are ensured.

  Moreover, in this pneumatic tire 1, the wall angle α of the recess 8 is in a range of −85 [deg] ≦ α ≦ 95 [deg] (see FIG. 5). Thereby, there exists an advantage which the edge effect | action of the recessed part 8 improves.

  Moreover, in this pneumatic tire 1, the depth Hd of the recessed part 8 and the groove depth Hg of the thin shallow groove 7 have the relationship of 0.5 <= Hd / Hg <= 1.5 (refer FIG. 5). Thereby, there exists an advantage by which the depth Hd of the recessed part 8 is optimized. That is, when 0.5 ≦ Hd / Hg, the water absorbing action of the recess 8 is ensured. Moreover, by being Hd / Hg <= 1.5, the rigidity fall of the land parts 31-33 resulting from the recessed part 8 being too deep with respect to the thin shallow groove 7 can be suppressed.

  Moreover, in this pneumatic tire 1, the land parts 31-33 equip the grounding surface with the some sipe 6, and the recessed part 8 is spaced apart and arrange | positioned from the sipe 6 (for example, refer FIG. 3). In such a configuration, since the concave portion 8 and the sipe 6 are arranged separately from each other, there is an advantage that the rigidity of the land portions 31 to 33 is ensured and the braking performance of the tire on ice is improved.

  In the pneumatic tire 1, a plurality of sipes 6 are arranged in parallel to divide the land portion 32 into a plurality of sections in the tire circumferential direction (not shown). Further, the section having the recess 8 only in the central region in the tire width direction and the section having the recess 8 only in the end region in the tire width direction are alternately arranged in the tire circumferential direction. In such a configuration, since the concave portions 8 are arranged in a dispersed manner, there is an advantage that the rigidity of the land portion can be ensured while enhancing the water film absorbing action by the concave portions 8. Moreover, since each continuous section has a recess, the water film on the icy road surface is efficiently absorbed, and there is an advantage that the braking performance on ice of the tire is improved.

  Moreover, in this pneumatic tire 1, the some sipe 6 is arrange | positioned in parallel with a tire peripheral direction, and divides the land parts 31-33 into a some area. In addition, at least one of any pair of adjacent sections has a recess 8 in an end region in the tire width direction (see FIGS. 3 and 7). Thereby, the recessed part 8 is arrange | positioned densely in the edge part area | region of a tire width direction. As a result, there is an advantage that the water film on the ice road surface is efficiently absorbed and the braking performance on the ice of the tire is improved.

  Moreover, in this pneumatic tire 1, the some sipe 6 is arrange | positioned in parallel with a tire peripheral direction, and divides the land parts 31-33 into a some area. Further, three adjacent sections include the section having the recess 8 in the end region in the tire width direction and the section having the recess 8 in the center region in the tire width direction (for example, FIG. 3 and (See FIG. 6). Thereby, there exists an advantage by which the recessed part 8 is disperse | distributed and arrange | positioned at the edge part area | region and center part area | region of the land parts 31-33.

  Moreover, in this pneumatic tire 1, the some sipe 6 is arrange | positioned in parallel with a tire peripheral direction, and divides the land parts 31-33 into a some area. Further, the arbitrary three sections adjacent in the tire circumferential direction include the section having the recess 8 and the section not having the recess 8 (see FIG. 7). In such a configuration, the recesses 8 are dispersedly arranged by arranging the sections not having the recesses 8. Thereby, the ground contact area of the land parts 31-33 is ensured and there exists an advantage which the braking performance on ice of a tire improves.

  Moreover, in this pneumatic tire 1, land part 31-33 is a block row | line | column which has the some block 5, and has the recessed part 8 in the corner | angular part of the block 5 (refer FIG.3, FIG.6 and FIG.7). In such a configuration, the concave portion 8 is disposed at the corner of the block 5 where the ground pressure is high and a water film is likely to be generated. As a result, there is an advantage that the water film on the ice road surface is efficiently absorbed and the braking performance on the ice of the tire is improved.

  Further, in this pneumatic tire 1, the land portions 31 to 33 are block rows having a plurality of blocks 5, and the recesses 8 are provided at the end portions of the blocks 5 in the tire circumferential direction and in the central region in the tire width direction. No (see FIGS. 3, 6 and 7). Accordingly, there is an advantage that the ground contact area and the rigidity of the end portions of the block 5 on the stepping side and the kicking side are ensured, and the braking performance on the ice of the tire is improved.

  Moreover, in this pneumatic tire 1, the recessed part 8 has circular shape (refer FIG. 4) or elliptical shape (illustration omitted) in the ground-contact surface of the land parts 31-33. Thereby, compared with the structure (illustration omitted) in which the recessed part 8 has a polygon, there exists an advantage which can suppress the uneven wear of the ground-contact surface of the land parts 31-33.

  In the pneumatic tire 1, at least a part of the recesses 8 is disposed at a position corresponding to a vent mark (not shown) of the tire molding die. There is an advantage that the vent mark can be effectively used, and unnecessary dents in the ground contact surfaces of the land portions 31 to 33 can be reduced to appropriately ensure the contact area of the land portions 31 to 33.

  Moreover, in this pneumatic tire 1, the some shallow groove 7 has a longitudinal shape, and is arrange | positioned in parallel mutually (refer FIG. 4, FIG. 8-14). In such a configuration, since the thin shallow groove 7 has a longitudinal shape, the water film absorbed in the thin shallow groove 7 can be guided and discharged in the longitudinal direction of the thin shallow groove 7. Moreover, since the recessed part 8 is arrange | positioned ranging over the some thin shallow groove | channel 7 which has this longitudinal shape, the recessed part 8 becomes a reservoir of the absorbed water film, and the water absorption of the land parts 31-33 improves. As a result, there is an advantage that the braking performance on ice of the tire is improved.

  Further, in the pneumatic tire 1, the plurality of thin shallow grooves 7 have an annular shape and are arranged separately from each other (see FIGS. 15 and 16). In such a configuration, the rigidity of the land portions 31 to 33 is higher than the configuration in which the thin shallow groove 7 penetrates the land portions 31 to 33. Thereby, there exists an advantage which the braking performance on ice of a tire improves.

  Moreover, in this pneumatic tire 1, the several thin shallow groove | channel 7 is arrange | positioned at mesh shape (refer FIGS. 18-20). Thereby, the groove area of the thin shallow groove 7 is increased, and there is an advantage that the absorption action of the water film by the thin shallow groove 7 is improved.

  Further, in the pneumatic tire 1, the plurality of shallow grooves 7 have an annular shape and are arranged in communication with each other (see FIG. 21). Thereby, the groove area of the thin shallow groove 7 is increased, and there is an advantage that the absorption action of the water film by the thin shallow groove 7 is improved.

  24 and 25 are charts showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  In this performance test, the performance on snow was evaluated for multiple types of test tires. Further, a test tire having a tire size of 195 / 65R15 is assembled to an applicable rim defined by JATMA, and an air pressure of 230 [kPa] and a maximum load defined by JATMA are applied to the test tire. Further, the test tire is mounted on a sedan having a displacement of 1600 [cc] and a front engine front drive (FF) system, which is a test vehicle.

  In the evaluation on the performance on snow, the test vehicle travels on the snow road surface of the snow road test site, and the driving performance and the braking distance from the traveling speed of 40 [km / h] are measured. Then, based on this measurement result, index evaluation using the conventional example as a reference (100) is performed. This evaluation is preferable as the numerical value increases.

  24, the test tires of Examples 1 to 7 have the configurations of FIGS. 1 and 2, and the blocks 5 of the land portions 31 to 33 have sipes 6, thin shallow grooves 7, and recesses 8, respectively. Further, as shown in FIG. 4, linear thin shallow grooves 7 are arranged in parallel while being inclined in the tire circumferential direction and penetrate the block 5. Moreover, the groove width and the groove depth Hg of the thin shallow groove 7 are 0.3 [mm]. Moreover, all the recessed parts 8 in a tread surface have the same shape and a fixed opening area. In addition, the arrangement density of the concave portions 8 in each of the land portions 31 to 33 is in the range of 0.8 [pieces / cm ^ 2] or more and 4.0 [pieces / cm ^ 2] or less. And within the range of the arrangement density, the arrangement density Din, Dout of the outer region in the vehicle width direction and the inner region in the vehicle width direction, and the arrangement of the recesses 8 in the center land portion 31, the second land portion 32, and the shoulder land portion 33. Densities D1, D2 and D3 are adjusted.

  25, the test tires of Examples 8 to 15 have the configurations of FIGS. 1 and 22, and the blocks 5 of the land portions 31 to 33 have sipes 6, thin shallow grooves 7, and recesses 8, respectively. Further, as shown in FIG. 4, linear thin shallow grooves 7 are arranged in parallel while being inclined in the tire circumferential direction and penetrate the block 5. Moreover, the groove width and the groove depth Hg of the thin shallow groove 7 are 0.3 [mm]. In addition, all the blocks 5 on the tread surface are provided with a plurality of recesses 8, and two types of recesses having different opening areas are used. Moreover, the recessed part 8 which has the large opening area Aout is arrange | positioned in the vehicle width direction outer side area | region, and the recessed part 8 which has a small opening area Ain is arrange | positioned in the vehicle width direction inner side area | region. In addition, the arrangement density Da of the recesses 8 in each block 5 is in the range of 0.8 [pieces / cm 2] or more and 4.0 [pieces / cm 2] or less. Further, the test tire has a point-symmetric tread pattern with the tire equatorial plane CL as a boundary, and also has an arrangement pattern of the point-symmetric concave portions 8.

  In the test tires of Conventional Examples 1 and 2, in the configuration of FIG. 2, the block 5 has only the sipe 6 and the thin shallow groove 7, and does not have the recess 8.

  As shown in the test results, it can be seen that in the test tires of Examples 1 to 15, the on-snow performance of the tire is improved.

  1: Pneumatic tire, 21, 22: circumferential main groove, 23: circumferential narrow groove, 31-33: land portion, 311: notch portion, 41-43: lug groove, 5: block, 6: sipe, 7 : Thin shallow groove, 8: Recess, 11: Bead core, 12: Bead filler, 13: Carcass layer, 14: Belt layer, 141, 142: Cross belt, 143: Belt cover, 15: Tread rubber, 16: Side wall rubber , 17: Rim cushion rubber

Claims (15)

In a pneumatic tire having a land portion having a rib or a plurality of blocks on a tread surface, and a mounting direction display portion that displays a mounting direction with respect to the vehicle,
The land portion is provided with a plurality of shallow grooves and a plurality of recesses on the ground surface,
Defining the ratio of the sum of the opening areas of the recesses in a predetermined area and the contact area of the land part as the opening area ratio of the recesses; and
The opening area ratio Sin of the recess in the inner region in the vehicle width direction bounded by the tire equator plane and the opening area ratio Sout of the recess in the outer region in the vehicle width direction have a relationship of Sin <Sout. Pneumatic tire.   The opening area ratio Sin of the concave portion in the vehicle width direction inner region and the opening area ratio Sout of the concave portion in the vehicle width direction outer region have a relationship of 1.10 ≦ Sout / Sin. Pneumatic tire. Defining the ratio of the number of the recessed portions arranged in a predetermined region and the contact area of the land portion as the placement density of the recessed portions; and
2. The pneumatic tire according to claim 1, wherein an arrangement density Din of the recesses in the inner region in the vehicle width direction and an arrangement density Dout of the recesses in the outer region in the vehicle width direction have a relationship of Din <Dout.   2. The pneumatic tire according to claim 1, wherein an arrangement density Din of the recesses in an inner region in the vehicle width direction and an arrangement density Dout of the recesses in an outer region in the vehicle width direction have a relationship of 1.10 ≦ Dout / Din.   The average value Ain of the opening area of the recess in the vehicle width direction inner area and the average value Aout of the opening area of the recess in the outer area in the vehicle width direction have a relationship of Ain <Aout. The described pneumatic tire.   The average value Ain of the opening area of the recess in the vehicle width direction inner region and the average value Aout of the opening area of the recess in the outer region in the vehicle width direction have a relationship of 1.10 ≦ Aout / Ain. 5. The pneumatic tire according to 5.   The inner region in the vehicle width direction includes a plurality of types of the recesses having different opening areas, and 70% or more of the recesses arranged in the inner region in the vehicle width direction is an average of the entire tread portion. The pneumatic tire according to claim 5 or 6 having a smaller opening area.   The vehicle width direction outside region includes a plurality of types of the recesses having mutually different opening areas, and 70 [%] or more of the recesses arranged in the vehicle width direction outside region is an average of the entire tread portion. The pneumatic tire according to any one of claims 5 to 7, which has a larger opening area. Comprising four or more circumferential main grooves and five or more rows of land portions defined by the circumferential main grooves; and
The left and right circumferential main grooves on the outermost side in the tire width direction are defined as outermost circumferential main grooves,
The distance between the left and right outermost circumferential main grooves and the tire equatorial plane is in the range of 28 [%] to 38 [%] of the tire ground contact width;
The opening area ratio S1 of the concave portion in the land portion on the tire equator plane or the land portion in the circumferential direction main groove on the tire equator surface, and the tire width in the outermost direction main groove The opening area ratio S2 of the recess in the land portion on the inner side in the direction and the opening area ratio S3 of the recess in the land portion on the outer side in the tire width direction partitioned by the outermost circumferential main groove are S1 <S2 and S3. The pneumatic tire according to any one of claims 3 to 8, which has a relationship of <S2. Comprising four or more circumferential main grooves and five or more rows of land portions defined by the circumferential main grooves; and
The left and right circumferential main grooves on the outermost side in the tire width direction are defined as outermost circumferential main grooves,
The distance between the left and right outermost circumferential main grooves and the tire equatorial plane is in the range of 28 [%] to 38 [%] of the tire ground contact width;
The opening area ratio S1 of the concave portion in the land portion on the tire equator plane or the land portion in the circumferential direction main groove on the tire equator surface, and the tire width in the outermost direction main groove The pneumatic tire according to any one of claims 3 to 9, wherein an opening area ratio S3 of the concave portion in the land portion on the outer side in the direction has a relationship of S1 <S3. Comprising four or more circumferential main grooves and five or more rows of land portions defined by the circumferential main grooves; and
The left and right circumferential main grooves on the outermost side in the tire width direction are defined as outermost circumferential main grooves,
The distance between the right and left outermost circumferential main grooves and the tire equatorial plane is in the range of 28 [%] to 38 [%] of the tire ground contact width,
The land portion on the inner side in the tire width direction defined by the outermost circumferential main groove includes a circumferential narrow groove extending in the tire circumferential direction, and
The relationship between the opening area ratio S21 of the recess in the tire width direction inner area of the land section partitioned by the circumferential narrow groove and the opening area ratio S22 of the recess in the outer area in the tire width direction is S21 <S22. The pneumatic tire according to any one of claims 1 to 10.   The arrangement density Da of the concave portions on the continuous ground contact surface of the land portion is in the range of 0.8 [pieces / cm ^ 2] ≦ Da ≦ 4.0 [pieces / cm ^ 2]. The pneumatic tire according to any one of the above.   The pneumatic tire according to any one of claims 1 to 12, wherein an opening area of the recess is in a range of 2.5 [mm ^ 2] to 10 [mm ^ 2].   The pneumatic tire according to any one of claims 1 to 13, wherein a wall angle α of the recess is in a range of -85 [deg] ≤ α ≤ 95 [deg].   The pneumatic according to any one of claims 1 to 14, wherein a depth Hd of the concave portion and a groove depth Hg of the thin shallow groove have a relationship of 0.5 ≦ Hd / Hg ≦ 1.5. tire.

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