JP6019780B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can achieve both dry and snow handling characteristics.

  A general winter tire has a sipe in the tread portion in order to improve the snow maneuverability of the tire. As a conventional pneumatic tire employing such a configuration, a technique described in Patent Document 1 is known.

  In addition, in order to improve the dry maneuverability of the tire, a configuration including a tread rubber having different rubber hardnesses between the cap rubber and the under rubber is known. As a conventional pneumatic tire employing such a configuration, a technique described in Patent Document 2 is known.

  In addition, in order to improve the dry maneuverability of the tire, a configuration including an under rubber having different rubber hardnesses in the tread portion center region and the shoulder region is known. As a conventional pneumatic tire employing such a configuration, a technique described in Patent Document 3 is known.

JP 2010-6107 A JP 2009-262646 A JP 2000-198319 A

  An object of the present invention is to provide a pneumatic tire that can achieve both dry maneuverability and snow maneuverability.

In order to achieve the above object, a pneumatic tire according to the present invention includes a plurality of circumferential main grooves extending in a tire circumferential direction and a plurality of land portions defined by the circumferential main grooves as tread portions. A pneumatic tire provided with a region where 35% of the tread pattern development width from one end of the tread is referred to as an inner region, and a region of 35% of the tread pattern development width from the other tread end is referred to as an outer region. Further, the land portion in the inner region and the land portion in the outer region each have a plurality of sipes, and 90% or more of the sipes arranged in the inner region are made of two-dimensional sipes. In addition, 90% or more of the sipe disposed in the outer region is formed of a three-dimensional sipe, the tread portion has cap rubber and under rubber, and 20 [° C. of the cap rubber. And the rubber hardness H_cap in, and the rubber hardness H_ut at 20 [° C.] of the under rubber, H_cap <have a relationship H_ut, and, in the mounting direction to be attached to the vehicle by the inner region in the vehicle width direction inside Characterized by having a designation .

  In the pneumatic tire, the rubber hardness H_cap of the cap rubber, the rubber hardness H_ut_in of the under rubber in the inner region at 20 [° C.], and the rubber hardness of the under rubber in the outer region at 20 [° C.]. H_ut_out has a relationship of H_cap <H_ut_in <H_ut_out.

  In this pneumatic tire, the average thickness t_in of the under rubber in the inner region and the average thickness t_out of the under rubber in the outer region are 0.5 [mm] ≦ t_out−t_in ≦ 3. It has a relationship of 0 [mm].

  In this pneumatic tire, the sipe density D_in in the inner region and the sipe density D_out in the outer region have a relationship of 1.3 ≦ D_in / D_out ≦ 2.0.

  In this pneumatic tire, the groove area ratio S_in of the inner region and the groove area ratio S_out of the outer region on the tire contact surface have a relationship of 1.2 ≦ S_in / S_out ≦ 2.0, and The total groove area ratio S_t on the tire contact surface is in the range of 0.25 ≦ S_t ≦ 0.38.

  In the pneumatic tire, the tread portion includes the three circumferential main grooves and the four land portions, and the contact width of the land portion on the contact end of the inner region is A plurality of inclined grooves that are wider than a ground contact width of the land portion on the ground contact end of the outer region and in which the land portion of the inner region is inclined with respect to the tire circumferential direction, and a tire width direction from the outer side of the tire contact surface A plurality of first lug grooves extending in the tire width direction and communicating with the inclined grooves, and a plurality of second lug grooves extending in the tire width direction and connecting the inclined grooves and the circumferential main grooves. Three or more first lug grooves communicate with the inclined grooves.

  In the pneumatic tire 1 according to the present invention, since the two-dimensional sipes 312 and 322 are arranged in the inner region and the three-dimensional sipes 332 and 342 are arranged in the outer region, the rigidity of the inner region is low and the rigidity of the outer region is low. It is set high (see FIG. 2). Therefore, the inner region contributes to the improvement of snow maneuverability (particularly, turning performance on snow), and the outer region contributes to the improvement of dry maneuverability (particularly, high-speed lane change performance). Accordingly, there is an advantage that the dry maneuverability of the tire and the snow maneuverability are compatible at a high level. In addition, since the rubber hardness H_cap of the cap rubber 151 and the rubber hardness H_ut of the under rubber 152 have a relationship of H_cap <H_ut, there is an advantage that the snow maneuverability is improved.

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 an example of a three-dimensional sipe. FIG. 4 is an explanatory diagram illustrating an example of a three-dimensional sipe. FIG. 5 is an explanatory view illustrating a first modification of the pneumatic tire depicted in FIG. 1. FIG. 6 is an explanatory diagram illustrating a second modification of the pneumatic tire depicted in FIG. 1. FIG. 7 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. FIG. 2 is a plan view showing a tread surface of the pneumatic tire depicted in FIG. 1. These drawings show a radial tire for a passenger car. In FIG. 1, the undertread rubber is hatched.

  The pneumatic tire 1 includes a pair of bead cores 11, 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, a tread rubber 15, and a pair of sidewall rubbers 16, 16. (See FIG. 1). The pair of bead cores 11 and 11 has an annular structure and constitutes the core of the left and right bead portions. The pair of bead fillers 12 and 12 are disposed on the outer periphery in the tire radial direction of the pair of bead cores 11 and 11 to reinforce the bead portion. The carcass layer 13 has a single-layer structure and is bridged in a toroidal shape between the left and right bead cores 11 and 11 to constitute a tire skeleton. 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 belt layer 14 includes a pair of stacked belt plies 141 and 142, and is disposed on the outer periphery in the tire radial direction of the carcass layer 13. These belt plies 141 and 142 are formed by arranging and rolling a plurality of belt cords made of steel or organic fiber material, and cross-ply structure by inclining the belt cords in mutually different directions in the tire circumferential direction. Configure. 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 pneumatic tire 1 includes a plurality of circumferential main grooves 21 to 23 that extend in the tire circumferential direction and a plurality of land portions 31 to 34 that are partitioned by the circumferential main grooves 21 to 23. (See FIG. 2). The circumferential main groove refers to a circumferential groove having a groove width of 3 [mm] or more. The land portions 31 to 34 may be block rows (see FIG. 2) or ribs (not shown).

  Further, an area of 35% of the tread pattern development width PDW from one end of the tread is referred to as an inner area. Further, an area of 35% of the tread pattern development width PDW from the other tread edge is referred to as an outer area. The structural differences between the inner region and the outer region will be described later. The tread pattern development width PDW refers to a linear distance between both ends in the development view of the tread pattern portion of the tire when the tire is mounted on the prescribed rim and applied with the prescribed internal pressure and is not loaded.

  In addition, the pneumatic tire 1 has a designation (not shown) of the mounting direction to be mounted on the vehicle with the inner region inward in the vehicle width direction. The designation of the mounting direction can be displayed by, for example, a mark or unevenness on the sidewall portion of the tire.

  For example, in this embodiment, the pneumatic tire 1 has a symmetrical tread pattern. Moreover, the pneumatic tire 1 has three circumferential main grooves 21 to 23. A central circumferential main groove 22 is arranged on the tire equatorial plane CL. In addition, these center main grooves 21 to 23 define two center land portions 32 and 33 and a pair of left and right shoulder land portions 31 and 34. Here, the three circumferential main grooves 21 to 23 and the four land parts 31 to 34 are arranged in order from the inner side in the vehicle width direction to the outer side in the vehicle width direction. , The second land portion 32, the second circumferential main groove 22, the third land portion 33, the third circumferential main groove 23, and the fourth land portion 34.

  Each land part 31-34 has a plurality of lug grooves 311 to 341 extending in the tire width direction, respectively. Moreover, these lug grooves 311 to 341 are arranged at predetermined intervals in the tire circumferential direction. Further, the lug groove 321 of the second land portion 32 and the lug groove 331 of the third land portion 33 each have an open structure, and the left and right sides cross the second land portion 32 and the third land portion 33 in the tire width direction. Each edge is open. Thereby, the 2nd land part 32 and the 3rd land part 33 are parted in the tire peripheral direction, and the block row | line | column is formed. On the other hand, the lug groove 311 of the first land portion 31 and the lug groove 341 of the fourth land portion 34 have a semi-closed structure, and open to the edge portion at the outer end in the tire width direction, respectively. It ends in the land at the end of Accordingly, the first land portion 31 and the fourth land portion 34 are ribs that are continuous in the tire circumferential direction.

[Sipe composition and rubber hardness]
Moreover, in this pneumatic tire 1, each land part 31-34 has several sipes 312-342, respectively (refer FIG. 2). Further, 90% or more of the sipes 312 and 322 arranged in the inner region are made up of two-dimensional sipes, and 90% or more of the sipes 332 and 342 arranged in the outer region are made up of three-dimensional sipes.

  Here, sipe refers to a cut formed in the land. The two-dimensional sipe means a sipe having a straight sipe wall surface in a cross-sectional view perpendicular to the sipe length direction. The three-dimensional sipe refers to a sipe having a sipe wall surface that is bent in the sipe width direction in a cross-sectional view perpendicular to the sipe length direction. The three-dimensional sipe has an action of reinforcing the rigidity of the land portion because the meshing force of the opposing sipe wall surfaces is stronger than that of the two-dimensional sipe.

  For example, in this embodiment, the first land portion 31, the second land portion 32, the third land portion 33, and the fourth land portion 34 have a plurality of sipes 312 to 342, respectively. Further, these sipes 312 to 342 have a straight shape extending in the tire width direction, and are arranged in parallel and at predetermined intervals in the tire circumferential direction. Further, these sipes 312 to 342 have a closed structure and terminate in the land portions 31 to 34, respectively. The sipe 312 of the first land portion 31 and the sipe 322 of the second land portion 32 are all two-dimensional sipe, and the sipe 332 of the third land portion 33 and the sipe 342 of the fourth land portion 34 are all three-dimensional. It is sipe. Therefore, due to the difference in rigidity between the two-dimensional sipes 312, 322 and the three-dimensional sipes 332, 342, the rigidity of the first land portion 31 and the second land portion 32 on the inner side in the vehicle width direction is low, and the first land portion 31 on the outer side in the vehicle width direction. The rigidity of the Sanriku portion 33 and the fourth land portion 34 is set high.

  Moreover, in this pneumatic tire 1, the tread portion includes the cap rubber 151 and the under rubber 152 (see FIG. 1). Further, the rubber hardness H_cap of the cap rubber 151 at 20 [° C.] and the rubber hardness H_ut of the under rubber 152 at 20 [° C.] have a relationship of H_cap <H_ut.

  Further, the rubber hardness H_cap of the cap rubber 151, the rubber hardness H_ut_in of the under rubber 152 in the inner region at 20 [° C.], and the rubber hardness H_ut_out of the under rubber 152 in the outer region of 20 [° C.] are H_cap <H_ut_in < It is preferable to have a relationship of H_ut_out.

  In addition, rubber hardness means the JIS-A hardness based on JIS-K6263. When the cap rubber or the under rubber in the predetermined region (inner region or outer region) is made of a plurality of rubber materials, the rubber hardness is calculated as the average rubber hardness by the following formula (1). In Equation (1), Sk represents the cross-sectional area of each rubber material in a cross-sectional view in the tire meridian direction, Hk represents the rubber hardness of each rubber material, and Sa represents a predetermined region in the cross-sectional view in the tire meridian direction. The cross-sectional area is shown.

  Rubber hardness H = (ΣSk × Hk) / Sa (k: 1, 2, 3,..., N) (1)

  For example, in this embodiment, the under rubber 152 is composed of an inner under rubber 152_in and an outer under rubber 152_out. Further, the inner under rubber 152_in is disposed in the inner region, and the outer under rubber 152_out is disposed in the outer region. At this time, the boundary between the inner under rubber 152_in and the outer under rubber 152_out is located below the groove bottom of the second circumferential main groove 22 on the tire equatorial plane CL. The rubber hardness H_ut_in of the inner under rubber 152_in and the rubber hardness H_ut_out of the outer under rubber 152_out have a relationship of H_ut_in <H_ut_out. Therefore, the rigidity of the first land portion 31 and the second land portion 32 in the inner region is low due to the difference in rubber hardness between these under rubbers 152_in and 152_out, and the third land portion 33 and the fourth land portion 34 in the outer region are low. The rigidity is set high.

  In this pneumatic tire 1, since the two-dimensional sipes 312 and 322 are arranged in the inner area and the three-dimensional sipes 332 and 342 are arranged in the outer area, the rigidity of the inner area is set low and the rigidity of the outer area is set high. (See FIG. 2). Therefore, the inner region contributes to the improvement of snow maneuverability (particularly, turning performance on snow), and the outer region contributes to the improvement of dry maneuverability (particularly, high-speed lane change performance). Thereby, dry maneuverability of the tire and snow maneuverability are compatible at a high level. Moreover, since the rubber hardness H_cap of the cap rubber 151 and the rubber hardness H_ut of the under rubber 152 have a relationship of H_cap <H_ut, the snow handling performance is improved.

  Furthermore, since the rubber hardness H_ut_in of the under rubber 152 in the inner region and the rubber hardness H_ut_out of the under rubber in the outer region have a relationship of H_ut_in <H_ut_out, the rigidity of the inner region is set low and the rigidity of the outer region is set high. The Therefore, the rigidity of the inner region is synergistically lowered and the rigidity of the outer region is synergistically reduced due to the relationship between the arrangement of the two-dimensional sipes 312 and 322 and the three-dimensional sipes 332 and 342 in the inner region and the outer region. Become expensive. Thereby, dry maneuverability of the tire and snow maneuverability are compatible at a high level.

  In the configuration of FIG. 1, the boundary between the inner under rubber 152_in and the outer under rubber 152_out is located below the bottom of the second circumferential main groove 22 on the tire equatorial plane CL. However, the present invention is not limited to this, and the boundary between the inner under rubber 152_in and the outer under rubber 152_out may be disposed at a position deviated from below the bottom of the second circumferential main groove 22 (not shown). At this time, when both the inner under rubber 152_in and the outer under rubber 152_out are arranged in one region (inner region or outer region), the rubber hardness (H_ut_in or H_ut_out) of the under rubber in this region is It is calculated based on the formula (1).

  3 and 4 are explanatory diagrams showing an example of a three-dimensional sipe. These drawings show perspective views of the wall surface of the three-dimensional sipe.

  In the three-dimensional sipe shown in FIG. 3, the sipe wall surface has a structure in which a triangular pyramid and an inverted triangular pyramid are connected in the sipe length direction. In other words, the sipe wall surface has a zigzag shape on the tread surface side and a zigzag shape on the bottom side that are shifted in pitch in the tire width direction, and unevenness that faces each other between the zigzag shapes on the tread surface side and the bottom side. Have Further, the sipe wall surface is an unevenness when viewed in the tire rotation direction among these unevennesses, between the convex bending point on the tread surface side and the concave bending point on the bottom side, the concave bending point on the tread surface side and the bottom side Between the convex bend points of the tread surface and the convex bend points on the tread surface side, and adjacent convex bend points that are adjacent to each other with ridge lines, and the ridge lines between the ridge lines in order in the tire width direction. It is formed by connecting in a plane. In addition, one sipe wall surface has an uneven surface in which convex triangular pyramids and inverted triangular pyramids are arranged alternately in the tire width direction, and the other sipe wall surface alternates between concave triangular pyramids and inverted triangular pyramids. Have uneven surfaces arranged in the tire width direction. And the sipe wall surface has the uneven | corrugated surface arrange | positioned at least at the outermost both ends of the sipe toward the outside of the block. As such a three-dimensional sipe, for example, a technique described in Japanese Patent No. 3894743 is known.

  In the three-dimensional sipe shown in FIG. 4, the sipe wall surface has a structure in which a plurality of rectangular columns having a block shape are connected in the sipe depth direction and the sipe length direction while being inclined with respect to the sipe depth direction. In other words, the sipe wall surface has a zigzag shape on the tread surface. Further, the sipe wall surface has a bent portion that is bent in the tire circumferential direction at two or more locations in the tire radial direction inside the block and continues in the tire width direction, and has an amplitude in the tire radial direction at the bent portion. It has a zigzag shape. In addition, while the sipe wall surface makes the tire circumferential amplitude constant, the inclination angle in the tire circumferential direction with respect to the normal direction of the tread surface is made smaller at the sipe bottom side part than the tread surface side part and bent. The amplitude of the tire in the tire radial direction is made larger at the sipe bottom side than at the tread surface side. As such a three-dimensional sipe, for example, a technique described in Japanese Patent No. 4316452 is known.

  In the pneumatic tire 1, the rubber hardness H_cap of the cap rubber 151, the rubber hardness H_ut_in of the under rubber 152 in the inner region, and the rubber hardness H_ut_out of the under rubber 152 in the outer region are 63 ≦ H_cap ≦ 74 and 68 ≦ H_ut_in ≦. Preferably, 76, 73 ≦ H_ut_out ≦ 80, 4 ≦ H_ut_in−H_cap ≦ 9, and 3 ≦ H_ut_out−H_ut_in ≦ 8 are satisfied. Accordingly, the rubber hardness H_cap of the cap rubber 151, the rubber hardness H_ut_in of the under rubber 152 in the inner region, the rubber hardness H_ut_out of the under rubber 152 in the outer region, and the rubber hardness differences H_ut_in−H_cap and H_ut_out−H_ut_in are optimized. Is done.

  In the pneumatic tire 1, it is preferable that the sipe density D_in in the inner region and the sipe density D_out in the outer region have a relationship of 1.3 ≦ D_in / D_out ≦ 2.0 (not shown). That is, it is preferable that the sipe density D_in in the inner region is higher than the sipe density D_out in the outer region.

  The sipe density is a ratio between the sipe length and the land contact area of the land. The sipe length can be increased by, for example, making the sipe a bent shape. The sipe density can be easily adjusted by adjusting the sipe length, the number of sipes, and the like.

  As described above, in the pneumatic tire 1, the land portion in the inner region is determined by the arrangement of the two-dimensional sipes 312, 322 and the three-dimensional sipes 332, 342 and the difference in rubber hardness between the inner under rubber 152_in and the outer under rubber 152_out. The rigidity of the land portions 33 and 34 in the outer region is set high. Therefore, by providing the above-described difference between the sipe densities D_in and D_out, the land portions 31 and 32 in the inner region are further lowered, and the rigidity of the land portions 33 and 34 in the outer region is set higher.

  In the pneumatic tire 1, the groove area ratio S_in of the inner region and the groove area ratio S_out of the outer region on the tire contact surface have a relationship of 1.2 ≦ S_in / S_out ≦ 2.0, and The total groove area ratio S_t on the tire ground contact surface is preferably in the range of 0.25 ≦ S_t ≦ 0.38 (see FIG. 2). Accordingly, the ratio S_in / S_out between the groove area ratio S_in of the inner region and the groove area ratio S_out of the outer region and the total groove area ratio S_t are optimized.

  The groove area ratio is defined as groove area / (groove area + ground area). The groove area refers to the opening area of the groove on the ground contact surface. The groove refers to a circumferential groove and a lug groove in the tread portion, and does not include sipes or kerfs. The ground contact area is the contact area between the tire and the ground contact surface. In addition, the groove area and the contact 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. Measured at the contact surface between the plate and the flat plate.

  Here, the prescribed rim refers to “applied rim” prescribed in JATMA, “Design Rim” prescribed in TRA, or “Measuring Rim” prescribed 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.

  Moreover, in this pneumatic tire 1, the average thickness t_in of the under rubber 152 in the inner region and the average thickness t_out of the under rubber 152 in the outer region are 0.5 [mm] ≦ t_out−t_in ≦ 3.0. [Mm] (see FIG. 1). Therefore, the average thickness t_in of the under rubber 152 in the inner region and the average thickness t_out of the under rubber 152 in the outer region are set to be substantially the same.

[Modification 1]
FIG. 5 is an explanatory view illustrating a first modification of the pneumatic tire depicted in FIG. 1.

  In the configuration of FIG. 2, three circumferential main grooves 21 to 23 are arranged. However, the present invention is not limited to this, and three or more circumferential main grooves 21 to 24 may be arranged (see FIG. 5).

  For example, in Modification 1 of FIG. 5, the four circumferential main grooves 21 to 24 are arranged symmetrically in the left and right regions with the tire equatorial plane CL as a boundary. Further, these center main grooves 21 to 24 divide three center land portions 32 to 34 and a pair of left and right shoulder land portions 31 and 35. Here, the four circumferential main grooves 21 to 24 and the five land parts 31 to 35 are arranged in order from the inner side in the vehicle width direction to the outer side in the vehicle width direction. , Second land portion 32, second circumferential main groove 22, third land portion 33, third circumferential direction main groove 23, fourth land portion 34, fourth circumferential direction main groove 24 and fifth land portion 35. .

  Further, the third land portion 33 is on the tire equator plane CL, and the boundary of the inner region and the boundary of the outer region are located on the second land portion 32 and the fourth land portion 34, respectively. Therefore, a part of the first land part 31 and the second land part 32 belong to the inner area, and a part of the fourth land part 34 and the fifth land part 35 belong to the outer area. Further, the second land portion 32 to the fourth land portion 34 have a plurality of lug grooves 321, 331, and 341, respectively, thereby forming a block row.

  Moreover, each land part 31-35 has the some sipe 312,322,332,342,352, respectively. Further, all the sipes 312 and 322 arranged in the first land portion 31 and the second land portion 32 in the inner region are two-dimensional sipes, and the fourth land portion 34 and the fifth land portion 35 in the outer region are arranged. All of the arranged sipes 342 and 352 are three-dimensional sipes.

  In addition, the sipe 332 arrange | positioned at the 3rd land part 33 on the tire equator surface CL may be a two-dimensional sipe, and a three-dimensional sipe may be sufficient as it. Alternatively, a two-dimensional sipe and a three-dimensional sipe may be mixed and arranged. In the configuration in which all the sipe 332 disposed in the third land portion 33 is a two-dimensional sipe, the snow maneuverability of the tire is improved. Conversely, in the configuration in which all the three-dimensional sipe is present, the dry maneuverability of the tire is improved. improves.

  In addition, the first land portion 31 and the second land portion 32 in the inner region are configured by the inner under rubber 152_in (rubber hardness H_ut_in is 68 ≦ H_ut_in ≦ 76), and the fourth land portion 34 and the fifth land in the outer region. The part 35 is composed of an outer under rubber 152_out (rubber hardness H_ut_out is 73 ≦ H_ut_out ≦ 80). For this reason, the rigidity of the 1st land part 31 and the 2nd land part 32 is low, and the rigidity of the 4th land part 34 and the 5th land part 35 is set high.

  The third land portion 33 on the tire equatorial plane CL may be configured by the inner under rubber 152_in or may be configured by the outer under rubber 152_out (not shown). In the configuration in which the third land portion 33 is made of the inner under rubber 152_in, the snow maneuverability of the tire is improved. Conversely, in the configuration of the outer under rubber 152_out, the dry maneuverability of the tire is improved.

  Moreover, in the pneumatic tire 1 of FIG. 5, each center land part 32-34 has the lug groove | channels 321-341 of an open structure, and becomes a block row | line | column. The left and right shoulder land portions 31 and 35 have semi-closed lug grooves 311 and 351 to form ribs. However, the present invention is not limited to this, and an arbitrary land portion may have any of lug grooves of an open structure, a semi-closed structure, and a closed structure (not shown). Each land portion may be either a block row or a rib (not shown). Furthermore, an arbitrary land portion may have an inclined groove (not shown).

  Further, in the pneumatic tire 1 of FIG. 5, the sipes 312 to 352 of the land portions 31 to 35 are all closed sipes. However, the present invention is not limited to this, and the arbitrary sipes 312 to 352 may be open sipes or semi-closed sipes (not shown).

[Modification 2]
FIG. 6 is an explanatory diagram illustrating a second modification of the pneumatic tire depicted in FIG. 1. This figure shows a winter tire for a passenger car having an asymmetric tread pattern.

  In the configuration of FIG. 2, the pneumatic tire 1 has a symmetrical tread pattern, and its sipe configuration and rubber hardness are asymmetrical. However, the present invention is not limited to this, and the pneumatic tire 1 may have a left-right asymmetric tread pattern (see FIG. 6).

  For example, in Modification 2 of FIG. 6, the pneumatic tire 1 is divided into three circumferential main grooves 21 to 23 extending in the tire circumferential direction and these circumferential main grooves 21 to 23. Two land portions 31 to 34 are provided in the tread portion. Further, the ground contact width of the first land portion 31 in the inner region is wider than the ground contact width of the fourth land portion 34 in the outer region. The first land portion 31 includes a plurality of main inclined grooves 313 inclined with respect to the tire circumferential direction, and a plurality of first inclined grooves 313 extending in the tire width direction from the outside of the tire contact surface and communicating with the inclined grooves 313. Lug grooves 314 </ b> _a and 314 </ b> _b and a plurality of second lug grooves 315 </ b> _a to 315 </ b> _c extending in the tire width direction and connecting the inclined groove 313 and the first circumferential main groove 21 are provided. Three first lug grooves 314 communicate with one inclined groove 313. In addition, the number of the 1st lug grooves 314 should just exist in the range of 3 or more and 6 or less.

  Moreover, in the modification 2 of FIG. 6, the arrangement | positioning space | interval of the tire circumferential direction of 2nd lug grooves 315_a-315_c is narrower than the arrangement | positioning space | interval of the tire circumferential direction of 1st lug grooves 314_a and 314_b. Thereby, the drainage property and snow traction property of the first land portion 31 are enhanced. Further, the inclination angle θ of the inclined groove 313 with respect to the tire circumferential direction is in the range of 10 [deg] ≦ θ ≦ 40 [deg]. Thereby, the inclination | tilt angle (theta) of the inclination groove | channel 313 is optimized. In addition, all or some of the plurality of second lug grooves 315_a to 315_c each have a bottom upper portion (not shown) that raises the groove bottom. Thereby, the bottom upper part reinforces the rigidity of the land portion 31.

  Further, the groove width W3 (not shown) of the second lug grooves 315_a to 315_c is set in a range of 2 [mm] ≦ W3 ≦ 6 [mm]. Accordingly, the groove width W3 of the second lug grooves 315_a to 315_c is optimized. Moreover, the 2nd land part 32 and the 3rd land part 33 have the several lug groove | channels 321 and 331 which penetrate each land part 32 and 33 to a tire width direction, respectively. All or some of the lug grooves 321 and 331 have a bottom upper portion (not shown) for raising the groove bottom. Thereby, the bottom upper part reinforces the rigidity of the land portions 32 and 33.

  Further, the distance DE to the tire ground contact end T with respect to the tire equatorial plane CL, the distance D1 to the first circumferential main groove 21 (groove center line) that defines the first land portion 31, and the fourth land The distance D3 to the third circumferential main groove 23 defining the portion 34 is 0.10 ≦ D1 / DE ≦ 0.30 (preferably 0.15 ≦ D1 / DE ≦ 0.25) and 0.55 ≦ D3 / DE ≦ 0.75 is satisfied. At this time, it is assumed that the first circumferential main groove 21 and the third circumferential main groove 23 are arranged with the tire equatorial plane CL interposed therebetween. Thereby, the relationship between the ground contact widths of the left and right first land portions 31 and the fourth land portions 34 is optimized. In the second modification of FIG. 6, the distance D2 of the second circumferential main groove 22 with respect to the tire equatorial plane CL is D2 = D1.

  The first land portion 31 has a circumferential thin shallow groove 25 that is disposed between the inclined groove 313 and the tire ground contact end T and extends in the tire circumferential direction. Further, the groove width W2 (not shown) and the groove depth Hd3 (not shown) of the circumferential narrow groove 25 are 2 [mm] ≦ W2 ≦ 4 [mm] and 2 [mm] ≦ Hd3 ≦ 4 [mm. ] Is set within the range. As a result, the snow traction increases due to the edge component of the circumferential narrow groove 25. In the second modification of FIG. 6, the distance D4 of the circumferential thin shallow groove 25 with respect to the tire equatorial plane CL is 0.50 ≦ D4 / DE ≦ 0.90.

  In the second modification of FIG. 6, as described above, the first land portion 31 in the inner region has a wide structure, and the first land portion 31 includes a plurality of inclined grooves 313 and a plurality of first lug grooves. By providing 314_a and 314_b and the plurality of second lug grooves 315_a to 315_c, the rigidity of the wide first land portion 31 is reduced, and the drainage of the first land portion 31 is ensured. Further, the three or more first lug grooves 314_a and 314_b communicate with one inclined groove 313, thereby improving the drainage performance and snow traction performance of the first land portion 31. As a result, it is possible to achieve both dry performance, wet performance and snow performance of the tire.

  Moreover, in the modification 2 of FIG. 6, each land part 31-34 has the some sipe 312-342, respectively. Moreover, in the 1st land part 31, each block divided by the inclination groove | channel 313, 1st lug groove 314_a, 314_b, and 2nd lug groove 315_a-315_c has the some sipe 312, respectively. In addition, 90% or more of the sipes 312 arranged in the first land portion 31 are constituted by two-dimensional sipes, and 90 of the sipes 332 and 342 arranged in the third land portion 33 and the fourth land portion 34. [%] Or more consists of three-dimensional sipes. Further, the rubber hardness H_ut_in of the under rubber 152_in in the first land portion 31 and the rubber hardness H_ut_out of the under rubber 152_out in the third land portion 33 and the fourth land portion 34 have a relationship of H_ut_in <H_ut_out.

  The sipe 322 disposed in the second land portion 32 on the tire equatorial plane CL may be a two-dimensional sipe or a three-dimensional sipe. Alternatively, a two-dimensional sipe and a three-dimensional sipe may be mixed and arranged. In the configuration in which all of the sipe 322 disposed in the second land portion 32 are two-dimensional sipe, the snow maneuverability of the tire is improved. improves.

  Further, the first land portion 31 in the inner region is composed of the inner under rubber 152_in (rubber hardness H_ut_in is 68 ≦ H_ut_in ≦ 76), and the third land portion 33 and the fourth land portion 34 in the outer region are the outer under rubber. 152_out (rubber hardness H_ut_out is 73 ≦ H_ut_out ≦ 80). For this reason, the rigidity of the 1st land part 31 is low, and the rigidity of the 3rd land part 33 and the 4th land part 34 is set high.

  The second land portion 32 on the tire equatorial plane CL may be constituted by the inner under rubber 152_in or may be constituted by the outer under rubber 152_out (not shown). In the configuration in which the third land portion 33 is made of the inner under rubber 152_in, the snow maneuverability of the tire is improved. Conversely, in the configuration of the outer under rubber 152_out, the dry maneuverability of the tire is improved.

  Moreover, in the modified example 2 of FIG. 6, the pneumatic tire 1 has the designation | designated which should be mounted | worn with a vehicle by making the 1st land part 31 which has a wide contact width into the vehicle width direction inside. In a general high-performance vehicle, the camber angle is set large in the negative direction, so that the tire ground contact length in the inner region in the vehicle width direction becomes long. Therefore, the snow traction is effectively improved by attaching the pneumatic tire 1 to the vehicle with the first land portion 31 positioned inward in the vehicle width direction.

  Note that the tire ground contact edge T and the tire ground contact width were applied to the tire by being mounted on the specified rim and applied with the specified internal pressure, and placed perpendicular to the flat plate in a stationary state and applied with a load corresponding to the specified load. It is specified or measured at the contact surface between the tire and the flat plate.

[effect]
As described above, the pneumatic tire 1 includes a plurality of circumferential main grooves 21 to 23 that extend in the tire circumferential direction and a plurality of land portions 31 that are partitioned by the circumferential main grooves 21 to 23. To 34 (see FIG. 2). Further, the land portions 31 and 32 in the inner region and the land portions 33 and 34 in the outer region have a plurality of sipes 312 to 342, respectively. Further, 90% or more of the sipes 312 and 322 arranged in the inner region are made up of two-dimensional sipes, and 90% or more of the sipes 332 and 342 arranged in the outer region are made up of three-dimensional sipes. Further, the tread portion has a cap rubber 151 and an under rubber 152 (see FIG. 1). Further, the rubber hardness H_cap of the cap rubber 151 at 20 [° C.] and the rubber hardness H_ut of the under rubber 152 at 20 [° C.] have a relationship of H_cap <H_ut.

  In such a configuration, since the two-dimensional sipes 312 and 322 are arranged in the inner region and the three-dimensional sipes 332 and 342 are arranged in the outer region, the rigidity of the inner region is set low and the rigidity of the outer region is set high (see FIG. 2). Therefore, the inner region contributes to the improvement of snow maneuverability (particularly, turning performance on snow), and the outer region contributes to the improvement of dry maneuverability (particularly, high-speed lane change performance). Accordingly, there is an advantage that the dry maneuverability of the tire and the snow maneuverability are compatible at a high level. In addition, since the rubber hardness H_cap of the cap rubber 151 and the rubber hardness H_ut of the under rubber 152 have a relationship of H_cap <H_ut, there is an advantage that the snow maneuverability is improved.

  In the pneumatic tire 1, the rubber hardness H_cap of the cap rubber 151, the rubber hardness H_ut_in of the under rubber 152 in the inner region at 20 [° C.], and the rubber hardness H_ut_out of the under rubber 152 in the outer region of 20 [° C.]. And H_cap <H_ut_in <H_ut_out (see FIG. 1). In such a configuration, the rigidity of the inner region is set low and the rigidity of the outer region is set high. Accordingly, the rigidity of the inner region is synergistically lowered and the rigidity of the outer region is synergistically increased due to the relationship between the arrangement of the two-dimensional sipe and the three-dimensional sipe in the inner region and the outer region. Accordingly, there is an advantage that the dry maneuverability of the tire and the snow maneuverability are compatible at a high level.

  In the pneumatic tire 1, the rubber hardness H_cap of the cap rubber 151, the rubber hardness H_ut_in of the under rubber 152 in the inner region, and the rubber hardness H_ut_out of the under rubber 152 in the outer region are 63 ≦ H_cap ≦ 74 and 68 ≦ H_ut_in ≦. 76, 73 ≦ H_ut_out ≦ 80. In such a configuration, the rubber hardness H_cap of the cap rubber 151, the rubber hardness H_ut_in of the under rubber 152 in the inner region, the rubber hardness H_ut_out of the under rubber 152 in the outer region, and these rubber hardnesses are optimized. There is an advantage that the maneuverability and the snow maneuverability are compatible at a higher level.

  Moreover, in this pneumatic tire 1, the average thickness t_in of the under rubber 152 in the inner region and the average thickness t_out of the under rubber 152 in the outer region are 0.5 [mm] ≦ t_out−t_in ≦ 3.0. [Mm] (see FIG. 1). As a result, there is an advantage that the dry maneuverability of the tire and the snow maneuverability are compatible at a higher level.

  Further, in the pneumatic tire 1, the sipe density D_in in the inner region and the sipe density D_out in the outer region have a relationship of 1.3 ≦ D_in / D_out ≦ 2.0. In such a configuration, since the ratio D_in / D_out between the sipe density D_in of the inner region and the sipe density D_out of the outer region is optimized, the advantage that the dry maneuverability and the snow maneuverability of the tire are compatible at a higher level can be achieved. There is.

  In the pneumatic tire 1, the groove area ratio S_in of the inner region and the groove area ratio S_out of the outer region on the tire contact surface have a relationship of 1.2 ≦ S_in / S_out ≦ 2.0, and The total groove area ratio S_t on the tire ground contact surface is in the range of 0.25 ≦ S_t ≦ 0.38. In such a configuration, the ratio S_in / S_out between the groove area ratio S_in of the inner region and the groove area ratio S_out of the outer region and the total groove area ratio S_t are optimized. However, there is an advantage that it is compatible at a higher level.

  Further, the pneumatic tire 1 includes three circumferential main grooves 21 to 23 and four land portions 31 to 34 in a tread portion (see FIG. 6). The ground contact width of the first land portion 31 on the ground contact end T in the inner region is wider than the ground contact width of the fourth land portion 34 on the ground contact end T in the outer region. The first land portion 31 has a plurality of inclined grooves 313 that are inclined with respect to the tire circumferential direction, and a plurality of first lug grooves that extend in the tire width direction from the outside of the tire contact surface and communicate with the inclined grooves 313. 314_a and 314_b, and a plurality of second lug grooves 315_a to 315_c extending in the tire width direction and connecting the inclined groove 313 and the circumferential main groove 21. Further, three or more first lug grooves 314 </ b> _a and 314 </ b> _b communicate with one inclined groove 313.

  In such a configuration, the first land portion 31 in the inner region has a wide structure, and the first land portion 31 includes a plurality of inclined grooves 313, a plurality of first lug grooves 314_a and 314_b, and a plurality of second lugs. By providing the grooves 315_a to 315_c, the rigidity of the wide first land portion 31 is reduced, and the drainage of the first land portion 31 is ensured. Further, the three or more first lug grooves 314_a and 314_b communicate with one inclined groove 313, thereby improving the drainage performance and snow traction performance of the first land portion 31. By these, there exists an advantage which can make dry performance, wet performance, and snow performance of a tire compatible.

  Moreover, this pneumatic tire 1 has designation | designated of the mounting direction which should be mounted | worn with a vehicle by making an inner side area | region inside vehicle width direction (refer FIG. 2). In such a configuration, the inner region having low rigidity is arranged on the inner side in the vehicle width direction, and the outer region having high rigidity is arranged on the outer side in the vehicle width direction. As a result, the inner area greatly contributes to the improvement of snow handling, and the outer area greatly contributes to the improvement of dry handling, so that the dry handling and snow handling of the tire are at a high level. There are advantages to both.

  FIG. 7 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  In this performance test, (1) dry maneuverability and (2) snow maneuverability were evaluated for a plurality of different pneumatic tires (see FIG. 7). In these performance tests, a pneumatic tire with a tire size of 235 / 45R19 is assembled to a rim with a rim size of 19 × 8J, and the pneumatic tire has a pneumatic pressure of 250 [kPa] and 85% of “LOAD CAPACITY” of ETRTO regulations. Is applied. As a test vehicle, a sedan type four-wheel drive vehicle having a displacement of 3.0 [L] is used.

  (1) In the evaluation relating to dry handling, a test vehicle equipped with a pneumatic tire travels on a test course having a flat circuit around 60 [km / h] to 240 [km / h]. Then, the test driver performs sensory evaluation on the steering performance at the time of lane change and cornering and the stability at the time of straight traveling. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the value, the better.

  (2) In the evaluation regarding snow maneuverability, a test vehicle equipped with pneumatic tires travels at a speed of 40 [km / h] on a handling course of a snowy road test site, and a test driver performs sensory evaluation. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the value, the better.

  The pneumatic tire 1 of Example 1 has the configuration described in FIGS. 1 and 2 and includes three circumferential main grooves 21 to 23 and four rows of land portions 31 to 34 in a tread portion. In addition, all the sipes 312, 322 of the first land portion 31 and the second land portion 32 in the inner region are formed of two-dimensional sipes, and all the sipes of the third land portion 33 and the fourth land portion 34 in the outer region. 332 and 342 are three-dimensional sipes. Further, the rubber hardness H_cap of the cap rubber 151, the rubber hardness H_ut_in of the under rubber 152 in the inner region, and the rubber hardness H_ut_out of the under rubber 152 in the outer region have a relationship of H_cap <H_ut_in <H_ut_out. Further, the sipe density D_in in the inner region and the sipe density D_out in the outer region have a relationship of 1.00 ≦ D_in / D_out. Further, the groove area ratio S_in of the inner region and the groove area ratio S_out of the outer region on the tire ground contact surface are adjusted by adjusting the groove area or the arrangement interval of the lug grooves of the land portions 31 to 34. Moreover, the pneumatic tire 1 of Examples 2-15 is a modification of the pneumatic tire 1 of Example 1.

  Moreover, the pneumatic tire 1 of Example 16 has the configuration described in FIG. 5 and includes four circumferential main grooves 21 and five land portions 31 to 35 in the tread portion. Further, the pneumatic tire 1 of Example 17 has the tread pattern of FIG. The boundary between the under rubber 152_in in the inner region and the under rubber 151_out in the outer region is on the second circumferential main groove 22. Moreover, all the sipes 312 of the 1st land part 31 consist of 2D sipes, and all the sipes 322-342 of the 2nd land part 32-the 4th land part 34 consist of 3D sipes.

  The conventional pneumatic tire has the block pattern shown in FIG.

  As shown in the test results, in the pneumatic tires 1 of Examples 1 to 17, it can be seen that the dry and snow handling characteristics of the tire are improved as compared with the conventional pneumatic tire (FIG. 7). reference). Further, when Examples 1 to 7 are compared, the relationship among the rubber hardness H_cap of the cap rubber 151, the rubber hardness H_ut_in of the under rubber 152 in the inner region, and the rubber hardness H_ut_out of the under rubber 152 in the outer region is optimized. Thus, it can be seen that the dry maneuverability of the tire and the snow maneuverability are compatible. Further, when Examples 8 to 11 are compared, the ratio D_in / D_out between the sipe density D_in in the inner region and the sipe density D_out in the outer region is optimized, so that the dry maneuverability and the snow maneuverability of the tire are improved. It turns out that is compatible. In addition, when Examples 8, 12, and 13 are compared, it can be seen that the dry area drivability and the snow area drivability of the tire are compatible by adjusting the groove area ratio S_in in the inner region.

  DESCRIPTION OF SYMBOLS 1 Pneumatic tire, 21-24 circumferential main groove, 25 circumferential shallow groove, 31-34 land part, 311, 321, 331, 341 lug groove, 312, 322, 332, 342 sipe, 313 inclined groove, 314 1st lug groove, 11 bead core, 12 bead filler, 13 carcass layer, 14 belt layer, 141, 142 belt ply, 15 tread rubber, 151 cap rubber, 152 under rubber, 152_in inner under rubber, 152_out outer under rubber, 16 side Wall rubber

Claims (6)

A pneumatic tire including a plurality of circumferential main grooves extending in the tire circumferential direction and a plurality of land portions defined by the circumferential main grooves in a tread portion,
When a region of 35% of the tread pattern development width from one tread end is called an inner region, and a region of 35% of the tread pattern development width from the other tread end is called an outer region,
The land portion of the inner region and the land portion of the outer region each have a plurality of sipes,
90% or more of the sipes arranged in the inner region are composed of two-dimensional sipes, and 90% or more of the sipes disposed in the outer region are composed of three-dimensional sipes,
The tread portion have a cap rubber and the under rubber,
And the rubber hardness H_cap at 20 [° C.] of the cap rubber, and the rubber hardness H_ut at 20 [° C.] of the under rubber, have a relationship H_cap <H_ut, and,
A pneumatic tire having a designation of a mounting direction to be mounted on a vehicle with the inner region inward in the vehicle width direction .   The rubber hardness H_cap of the cap rubber, the rubber hardness H_ut_in of the under rubber in the inner region at 20 [° C.], and the rubber hardness H_ut_out of the under rubber in the outer region at 20 [° C.] are H_cap <H_ut_in < The pneumatic tire according to claim 1, which has a relationship of H_ut_out. The average thickness t_in of the under rubber in the inner region and the average thickness t_out of the under rubber in the outer region have a relationship of 0.5 [mm] ≦ t_out−t_in ≦ 3.0 [mm]. The pneumatic tire according to claim 1 or 2 . The pneumatic tire according to any one of claims 1 to 3 , wherein a sipe density D_in in the inner region and a sipe density D_out in the outer region have a relationship of 1.3 ≦ D_in / D_out ≦ 2.0. . The groove area ratio S_in of the inner region and the groove area ratio S_out of the outer region on the tire contact surface have a relationship of 1.2 ≦ S_in / S_out ≦ 2.0, and the total groove area on the tire contact surface ratio S_t the pneumatic tire according to any one of claims 1-4 which is in the range of 0.25 ≦ S_t ≦ 0.38. The tread portion includes three circumferential main grooves and four land portions, and
The ground width of the land portion on the ground end of the inner region is wider than the ground width of the land portion on the ground end of the outer region,
The land portions of the inner region are inclined with respect to the tire circumferential direction, and a plurality of first lug grooves that extend in the tire width direction from the outer side of the tire contact surface and communicate with the inclined grooves. A plurality of second lug grooves extending in the tire width direction and connecting the inclined grooves and the circumferential main grooves,
The pneumatic tire according to any one of claims 1 to 5 , wherein three or more first lug grooves communicate with one inclined groove.

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