JP2013010442A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of making compatible all of dry performance, wet performance and snow performance.SOLUTION: The pneumatic tire 1 includes three main grooves 21-23 in peripheral direction extending in the tire peripheral direction and four lands 31-34 partitioned by these main grooves 21-23 in the peripheral direction in a tread. Also, in the pneumatic tire 1, the grounding width of the first land 31 in one tread shoulder region is wider than the grounding width of the fourth land 34 in the other tread shoulder region. Furthermore, the first land 31 having the wider grounding width includes a plurality of inclined grooves 311 inclined relative to the tire peripheral direction, a plurality of first lug grooves 312 extending in the tire width direction from the outside of the tire grounding surface and communicating with the inclined grooves 311, and a plurality of second lug grooves 313 extending in the tire width direction and connecting the inclined grooves 311 and the first main groove 21 in the peripheral direction with each other. Furthermore, three first lug grooves 312 communicate with one inclined groove 311.

Description

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

  Generally, in a pneumatic tire applied to a winter tire or the like, there is a problem that must satisfy both dry performance, wet performance, and snow performance. Here, as a conventional pneumatic tire having both dry performance and wet performance as problems, a technique described in Patent Document 1 is known.

JP 2008-105615 A

  An object of the present invention is to provide a pneumatic tire capable of achieving both dry performance, wet performance, and snow performance.

  In order to achieve the above object, a pneumatic tire according to the present invention includes three circumferential main grooves extending in the tire circumferential direction, and four land portions defined by the three circumferential main grooves. The tread part is a pneumatic tire, and the grounding width of the land part in one tread part shoulder region is wider than the grounding width of the land part in the other tread part shoulder area, and has a wide grounding width. The land portion has a plurality of inclined grooves that are inclined with respect to the tire circumferential direction, 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, and a tire width A plurality of second lug grooves extending in the direction and connecting the inclined groove and the circumferential main groove, and three or more and six or less first lugs with respect to one inclined groove The groove communicates with the groove.

  In the pneumatic tire according to the present invention, it is preferable that the arrangement interval of the second lug grooves is narrower than the arrangement interval of the first lug grooves.

  In the pneumatic tire according to the present invention, it is preferable that the inclination angle θ of the inclined groove is in a range of 10 [deg] ≦ θ ≦ 40 [deg].

  In the pneumatic tire according to the present invention, it is preferable that all or some of the plurality of second lug grooves each have a bottom upper portion that raises the groove bottom.

  In the pneumatic tire according to the present invention, it is preferable that the groove width W4 of the second lug groove is in a range of 2 [mm] ≦ W4 ≦ 6 [mm].

  In the pneumatic tire according to the present invention, the two land portions in the center region of the tread portion each have a plurality of lug grooves penetrating the land portion in the tire width direction, and the plurality of lug grooves It is preferable that all or some of the lug grooves have a bottom upper portion that raises the groove bottom.

  Further, in the pneumatic tire according to the present invention, the distance DE to the tire ground contact end with respect to the tire equator line, and the distance D1 to the circumferential main groove that divides the land portion in one shoulder region of the tread. The distance D3 to the circumferential main groove that divides the land portion in the other tread shoulder region is 0.10 ≦ D1 / DE ≦ 0.30 and 0.55 ≦ D3 / DE ≦ 0.75. It is preferable to have a relationship.

  In the pneumatic tire according to the present invention, the land portion having a wide contact width includes a circumferential shallow groove extending between the inclined groove and the tire contact end and extending in the tire circumferential direction. In addition, the groove width W2 and the groove depth H2 of the circumferential narrow groove are in the range of 2 [mm] ≦ W2 ≦ 4 [mm] and 2 [mm] ≦ H2 ≦ 4 [mm]. preferable.

  In the pneumatic tire according to the present invention, the two land portions in the tread region on the land portion side having a wide contact width have a two-dimensional sipe, and the two land portions in the other tread region. The part preferably has a three-dimensional sipe.

  Moreover, in the pneumatic tire according to the present invention, it is preferable that the land portion having a wide contact width is designated to be mounted on the vehicle with the land portion being inward in the vehicle width direction.

  In the pneumatic tire according to the present invention, one shoulder land portion (first land portion) has a wide structure, and the land portion includes a plurality of inclined grooves, a plurality of first lug grooves, and a plurality of second lugs. By providing the groove, the rigidity of the wide land portion is reduced, and the drainage of the land portion is ensured. Furthermore, when three or more first lug grooves communicate with one inclined groove, drainage performance and snow traction performance of the land portion are improved. By these, there exists an advantage which can make dry performance, wet performance, and snow performance of a tire compatible.

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 tread plan view showing the pneumatic tire depicted in FIG. 1. FIG. 3 is an enlarged view showing a shoulder land portion on the inner side in the vehicle width direction of the pneumatic tire depicted in FIG. 1. FIG. 4 is an enlarged view showing a center land portion of the pneumatic tire shown in FIG. 1. FIG. 5 is a perspective sectional view showing a three-dimensional sipe of the pneumatic tire shown in FIG. 1. FIG. 6 is a perspective sectional view showing a three-dimensional sipe of the pneumatic tire shown in FIG. 1. FIG. 7 is a table showing the results of performance tests according to the embodiment of the present invention. FIG. 8 is an explanatory view showing a conventional pneumatic tire.

  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 winter tire for a passenger car.

  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 carcass layer 13 is bridged in a toroidal shape between the left and right bead cores 11 and 11 to form 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. 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 three circumferential main grooves 21 to 23 extending in the tire circumferential direction, and four land portions 31 to 34 that are partitioned by the circumferential main grooves 21 to 23. Provided in the tread portion (see FIG. 2). Further, the ground contact width of the first land portion 31 in the one tread portion shoulder region is wider than the ground contact width of the fourth land portion 34 in the other tread portion shoulder region.

  For example, in this embodiment, one circumferential main groove 21 is disposed in one region having the tire equator line CL as a boundary, and two circumferential main grooves 22 and 23 are disposed in the other region. The Further, these circumferential main grooves 21 to 23 divide two rows of center land portions 32 and 33 and a pair of left and right shoulder land portions 31 and 34. Further, one of the left and right shoulder land portions 31, 34 has a wider structure than the other land portion 34. The widths of the land portions 31 and 34 are defined by the positions D1 / DE and D3 / DE of the circumferential main grooves 21 and 23 that partition the land portions 31 and 34. The positions D1 / DE and D3 / DE of the circumferential main grooves 21 and 23 will be described later.

  Further, in this embodiment, the three main circumferential grooves 21 to 23 and the four land portions 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 circumferential main groove 21, 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 are called.

  The pneumatic tire 1 has a designation to be mounted on the vehicle with the first land portion 31 side in the vehicle width direction (not shown). Therefore, the first land portion 31 is disposed in the inner region in the vehicle width direction and the fourth land portion 34 is disposed in the outer region in the vehicle width direction with the tire mounted on the vehicle (see FIG. 2). In addition, designation | designated of a mounting direction can be displayed by the mark or unevenness | corrugation attached | subjected to the sidewall part of the tire, for example.

[First land]
FIG. 3 is an enlarged view showing a shoulder land portion on the inner side in the vehicle width direction of the pneumatic tire depicted in FIG. 1. This figure shows an enlarged view of the first land portion having a wide structure.

  The first land portion 31 having a wide structure includes a plurality of inclined grooves 311, a plurality of first lug grooves 312_a and 312_b, and a plurality of second lug grooves 313_a to 313_c (see FIG. 2). The inclined groove 311 is a groove that is inclined with respect to the tire circumferential direction. The first lug grooves 312 — a and 312 — b are grooves that extend in the tire width direction from the outside of the tire contact surface and communicate with the inclined groove 311. The second lug grooves 313 — a to 313 — c are grooves that extend in the tire width direction and connect the inclined groove 311 and the first circumferential main groove 21. In addition, three or more and six or less first lug grooves 312 — a and 312 — b communicate with one inclined groove 311.

  For example, in this embodiment, the inclined groove 311 has a linear shape and extends while being inclined at an inclination angle θ with respect to the tire circumferential direction (see FIG. 3). In addition, the inclined groove 311 has a closed structure, and both end portions thereof terminate in the first land portion 31 and the tire ground contact surface. For this reason, the inclined groove 311 itself is non-penetrating with respect to the first circumferential main groove 21 and does not intersect the tire ground contact edge EL. A plurality of inclined grooves 311 are arranged at predetermined intervals in the tire circumferential direction. At this time, the adjacent inclined grooves 311 and 311 are arranged with their end portions wrapped in the tire circumferential direction.

  Further, the first lug grooves 312_a and 312_b extend in the tire width direction while being gently curved from the outer side of the tire contact surface in the tire circumferential direction and communicate with the inclined groove 311. Further, two types of first lug grooves 312_a and 312_b are alternately arranged in the tire circumferential direction at predetermined intervals P1_a and P1_b. One first lug groove 312_a crosses one inclined groove 311 out of a pair of adjacent inclined grooves 311 and 311 and is connected to the end of the other inclined groove 311 and terminates. Thereby, a zigzag groove formed by alternately connecting the inclined grooves 311 and the first lug grooves 312_a is formed. Further, the first land portion 31 is divided into two in the tire width direction by the zigzag groove. The other first lug groove 312 — b is connected to the middle part of the inclined groove 311 and terminates. Accordingly, the three first lug grooves 312_a, 312_b, and 312_a communicate with one inclined groove 311. Further, in the first land portion 31, a plurality of blocks 314 are formed which are partitioned into the first lug grooves 312_a and 312_b and the inclined grooves 311.

  The second lug grooves 313 </ b> _a to 313 </ b> _c have a linear shape, extend while inclining in the tire width direction, and connect the inclined groove 311 and the first circumferential main groove 21. At this time, one end of the second lug grooves 313 </ b> _a to 313 </ b> _c terminates in the inclined groove 311, and the other end opens to the first circumferential main groove 21. In addition, three types of second lug grooves 313 — a to 313 — c having different groove lengths are repeatedly arranged in the tire circumferential direction and at predetermined intervals P2 — a to P2 — c. Further, in the first land portion 31, a plurality of blocks 315 that are divided into the second lug grooves 313_a to 313_c, the inclined groove 311 and the first lug groove 312_a, and the first circumferential main groove 21. Is formed.

  In the above configuration, the first land portion 31 has a wide structure, and includes a plurality of inclined grooves 311, a plurality of first lug grooves 312_a and 312_b, and a plurality of second lug grooves 313_a to 313_c (FIG. 2). And FIG. 3). Therefore, the rigidity of the wide first land portion 31 is reduced by these grooves 311, 312_a, 312_b, and 313_a to 313_c, and the drainage of the tire is ensured. Further, the three or more first lug grooves 312 communicate with one inclined groove 311, thereby improving the drainage of the tire and increasing the edge component of the first land portion 31 to increase the snow traction. Improves.

  In this embodiment, the inclined groove 311 terminates in the block 314 between the inclined groove 311 and the tire ground contact end EL at the outer end in the tire width direction across the first lug groove 312_a. (See FIGS. 2 and 3). In such a configuration, the rigidity of the large block 314 between the inclined groove 311 and the tire ground contact edge EL can be reduced, which is preferable in terms of improving the tire dry performance. However, the present invention is not limited to this, and the inclined groove 311 may terminate at the first lug groove 312_a at the outer end in the tire width direction (not shown).

  Further, in this embodiment, the inclined groove 311 is terminated at the end portion on the inner side in the tire width direction so as to intersect the second lug groove 313 — a (see FIGS. 2 and 3). However, the present invention is not limited to this, and the inclined groove 311 traverses the second lug groove 313 — a at the inner end in the tire width direction, and in the block 315 between the inclined groove 311 and the first circumferential main groove 21. You may terminate.

  In this embodiment, all the first lug grooves 312_a and 312_b are terminated with the inclined grooves 311 (see FIGS. 2 and 3). However, the present invention is not limited to this, and for example, the first lug groove 312_b may terminate in the block 315 between the inclined groove 311 and the first circumferential main groove 21 across the inclined groove 311 (not shown). ).

  Further, in this embodiment, the first land portion 31 has a plurality of blocks 314 and 315 that are partitioned into an inclined groove 311, first lug grooves 312_a and 312_b, and second lug grooves 313_a to 313_c, and The other second land part 32 to the fourth land part 34 respectively have a plurality of blocks 322 to 342 that are partitioned into a plurality of lug grooves 321 to 341 (see FIG. 2). Therefore, each land part 31-34 has a block row, and the block pattern is formed as a whole. Such a configuration is preferable in that the snow performance and wet performance of the tire are improved. However, the present invention is not limited to this, and at least one of the second land portion 32 to the fourth land portion 34 may be a rib by not having a lug groove or having a non-through lug groove. (Not shown).

[Disposition interval of the first lug groove and the second lug groove]
In the pneumatic tire 1, the arrangement intervals P2_a to P2_c of the second lug grooves 313_a to 313_c are narrower than the arrangement intervals P1_a and P1_b of the first lug grooves 312_a and 312_b (see FIG. 3). That is, the number of second lug grooves 313 — a to 313 — c is greater than the number of first lug grooves 312 — a and 312 — b. For this reason, the block 315 located between the inclined groove 311 and the first circumferential main groove 21 is narrower in the tire circumferential direction than the block 314 located closer to the tire ground contact EL than the inclined groove 311. Such a configuration is preferable in that the drainage property and snow traction property of the first land portion 31 are improved.

  Specifically, it is preferable that three or more and six or less second lug grooves 313_a to 313_c are arranged for two first lug grooves 312_a and 312_b per unit pitch. For example, in this embodiment, three second lug grooves 313_a to 313_c are arranged for the two first lug grooves 312_a and 312_b (see FIG. 3). However, the present invention is not limited to this, and only one second lug groove (for example, the second lug groove 313_a in FIG. 3) is installed per two first lug grooves 312_a and 312_b per unit pitch. Good (not shown).

  The arrangement intervals P1_a and P1_b of the first lug grooves 312_a and 312_b and the arrangement intervals P2_a to P2_c of the second lug grooves 313_a to 313_c can be set as appropriate according to the tire size and specifications, and in the tire circumferential direction. It can change as you head (pitch variation).

[Inclination angle of inclined groove]
In the pneumatic tire 1, the inclination angle θ of the inclined groove 311 is preferably in the range of 10 [deg] ≦ θ ≦ 40 [deg], and 10 [deg] ≦ θ ≦ 30 [deg]. It is more preferable to be within the range (see FIG. 3). In such a configuration, the snow traction of the first land portion 31 is improved by the inclined groove 311 being inclined at an appropriate inclination angle θ with respect to the tire circumferential direction. Further, drainage performance from the inclined groove 311 to the outside of the ground contact surface is improved.

[The bottom upper part of the second lug groove on the shoulder land]
Moreover, in this pneumatic tire 1, in the 1st land part 31, all or some 2nd lug grooves 313_a-313_c of some 2nd lug grooves 313_a-313_c raise bottom bottom 316 which raises a groove bottom. It is preferable to have each (refer FIG. 3). The bottom upper portion 316 reinforces the rigidity of the block row between the inclined groove 311 and the first circumferential main groove 21 in the first land portion 31.

  For example, in this embodiment, the first land portion 31 includes three types of second lug grooves 313 — a to 313 — c, and these second lug grooves 313 — a to 313 — c are repeatedly arranged in the tire circumferential direction. In addition, among these second lug grooves 313 — a to 313 — c, two types of relatively long second lug grooves 313 — b and 313 — c each have a bottom upper portion 316. For this reason, the short second lug groove 313 — a does not have the bottom upper portion 316.

  Further, the bottom upper portions 316 and 316 adjacent to each other in the tire circumferential direction are arranged with their positions shifted in the tire width direction. For this reason, the plurality of bottom upper parts 316 are arranged in a zigzag shape as they go in the tire circumferential direction. Specifically, one bottom upper portion 316 is disposed at a position facing the opening on the inclined groove 311 side of the second lug groove 313_b, and the other bottom upper portion 316 is the first circumferential direction of the second lug groove 313_c. It is arranged at a position including the opening on the main groove 21 side. Thereby, the rigidity of the block row between the inclined groove 311 and the first circumferential main groove 21 can be effectively increased.

  Further, the bottom upper portion 316 is a region of 30% to 70% with respect to the groove lengths L1_b and L1_c of the second lug grooves 313_b and 313_c, preferably 30% to 50%. It is preferable to arrange in the region. Thereby, the drainage property and snow traction property of the second lug grooves 313_b and 313_c can be ensured while increasing the rigidity of the first land portion 31.

  Further, the bottom upper part 316 has a bottom raising height of 20% or more, preferably a bottom raising height of 30% to 50% with respect to the groove depth of the second lug grooves 313_b and 313_c. It is preferable. Thereby, the drainage property and snow traction property of the second lug grooves 313_b and 313_c can be ensured while increasing the rigidity of the first land portion 31.

[Groove width of the lug groove on the shoulder land]
In the pneumatic tire 1, the groove width W3 of the first lug grooves 312_a and 312_b of the first land portion 31 and the groove width W4 of the second lug grooves 313_a to 313_c are 0.20 ≦ W4 / W3 ≦. 0.99 (see FIG. 3). Thus, the rigidity of the block row between the inclined groove 311 and the first circumferential main groove 21 is ensured by setting the groove width W4 of the second lug grooves 313_a to 313_c to be small.

  At this time, the groove width W4 of the second lug grooves 313_a to 313_c is preferably in the range of 2 [mm] ≦ W4 ≦ 6 [mm]. Accordingly, the groove width W4 of the second lug grooves 313_a to 313_c is optimized.

[The bottom upper part of the lug groove in the center land]
FIG. 4 is an enlarged view showing a center land portion of the pneumatic tire shown in FIG. 1. The figure has shown the 2nd land part and the 3rd land part of a tread part center area | region.

  Moreover, in this pneumatic tire 1, the 2nd land part 32 and the 3rd land part 33 in a tread part center area | region respectively have several lug grooves 321 and 331 which penetrate each land part 32 and 33 in a tire width direction, respectively. (See FIG. 4). At this time, it is preferable that all or some of the lug grooves 321 and 331 have bottom upper portions 323 and 333 that raise the groove bottom. The bottom upper portions 323 and 333 reinforce the rigidity of the block rows of the second land portion 32 and the third land portion 33.

  For example, in this embodiment, the second land portion 32 and the third land portion 33 are partitioned into a plurality of lug grooves 321 and 331 arranged at predetermined intervals in the tire circumferential direction, and these lug grooves 321 and 331. And a plurality of blocks 322 and 332 respectively. Thereby, the 2nd land part 32 and the 3rd land part 33 are a block row. The groove widths of the lug grooves 321 and 331 are in the range of 2 [mm] to 6 [mm].

  Further, all the lug grooves 321 and 331 have bottom upper portions 323 and 333, respectively. Moreover, these bottom upper parts 323 and 333 are arrange | positioned facing the edge part located in the vehicle width direction outer side in the vehicle mounting state of a tire among the both ends of the lug grooves 321, 331. As a result, the block rigidity of the edge portion on the outer side in the vehicle width direction is increased, so that the dry performance of the tire is improved.

  Further, the bottom upper portions 323 and 333 are regions of 30% to 70% with respect to the groove lengths L2 and L3 of the lug grooves 321 and 331, preferably 30% to 60%. It is preferable to arrange in the region. Thereby, the drainage property and snow traction property of the lug grooves 321, 331 can be secured while increasing the rigidity of the second land portion 32 and the third land portion 33.

  Further, the bottom upper portions 323 and 333 have a bottom raising height of 20 [%] or more, preferably 30 [%] or more and 50 [%] or less with respect to the groove depth of the lug grooves 321 and 331. It is preferable. Thereby, the drainage property and snow traction property of the lug grooves 321, 331 can be secured while increasing the rigidity of the second land portion 32 and the third land portion 33.

[Position of circumferential main groove]
In addition, the distance DE to the tire contact point EL with respect to the tire equator line CL, the distance D1 to the first circumferential main groove 21, the distance D2 to the second circumferential main groove 22, and the third circumferential main groove 23. Distance D3 is defined (see FIG. 2). The distances D1 to D3 are measured as distances from the tire equator line CL to the groove center lines of the circumferential main grooves 21 to 23. When the tire is mounted on the vehicle, the first circumferential main groove 21 is located in the inner region in the vehicle width direction, and the second circumferential direction main groove 22 and the third circumferential main groove 23 are located outside in the vehicle width direction.

  At this time, the distance DE to the tire ground contact edge EL and the distances D1 to D3 to the circumferential main grooves 21 to 23 are 0.10 ≦ D1 / DE ≦ 0.30, 0.10 ≦ D2 / DE ≦. Preferably, the relationship is 0.30 and 0.55 ≦ D3 / DE ≦ 0.75, and 0.15 ≦ D1 / DE ≦ 0.25, 0.15 ≦ D2 / DE ≦ 0.25 and 0.60. It is more preferable to have a relationship of ≦ D3 / DE ≦ 0.70. Thereby, the relationship between the ground contact widths of the land portions 31 to 34, in particular, the ground contact widths of the first land portion 31 and the fourth land portion 34 in the left and right shoulder regions, is optimized.

[Circular circumferential shallow groove]
Further, in the pneumatic tire 1, the first land portion 31 has a circumferential thin shallow groove 24 that is disposed between the inclined groove 311 and the tire ground contact EL and extends in the tire circumferential direction (see FIG. 2 and FIG. 2). (See FIG. 3). Further, the groove width W2 and the groove depth H2 of the circumferential thin shallow groove 24 are in the range of 2 [mm] ≦ W2 ≦ 4 [mm] and 2 [mm] ≦ H2 ≦ 4 [mm]. Due to the edge component of the circumferential narrow groove 24, the snow traction is increased and the snow performance of the tire is improved.

  For example, in this embodiment, the circumferential thin shallow groove 24 has a linear shape and is disposed between the inclined groove 311 and the tire ground contact edge EL to divide the first land portion 31 in the tire width direction. Further, the distance DE from the tire equator line CL to the tire ground contact edge EL and the distance D4 from the circumferential thin shallow groove 24 have a relationship of 0.50 ≦ D4 / DE ≦ 0.90. Thereby, the position of the circumferential narrow groove 24 is optimized.

  Further, the groove width W1 of the first circumferential main groove 21 is in the range of 7 [mm] ≦ W1 ≦ 25 [mm], whereas the groove width W2 of the circumferential thin groove 24 is 0.08. ≦ W2 / W1 ≦ 0.60. Therefore, the circumferential narrow groove 24 is thinner than the first circumferential main groove 21. As a result, the groove width W2 of the circumferentially narrow shallow groove 24 is optimized.

  Further, the groove depth H1 of the first circumferential main groove 21 is in the range of 6 [mm] ≦ H1 ≦ 12 [mm], whereas the groove depth H2 of the circumferential thin shallow groove 24 is 0. .17 ≦ H2 / H1 ≦ 0.68 Accordingly, the circumferentially narrow shallow groove 24 is shallower than the first circumferential main groove 21. As a result, the groove depth H2 of the circumferentially narrow shallow groove 24 is optimized.

[Sipe]
5 and 6 are perspective sectional views showing a three-dimensional sipe of the pneumatic tire shown in FIG. The figure shows the wall of the 3D sipe in the third land.

  In the pneumatic tire 1, the first land portion 31 and the second land portion 32 in the vehicle width direction inner region have a plurality of two-dimensional sipes 317 and 324 and are in the vehicle width direction outer region. The Sanriku portion 33 and the fourth land portion 34 have a plurality of three-dimensional sipes 334 and 343 (see FIG. 2). Thereby, the rigidity difference between the land portions 31 and 32 in the vehicle width direction inner region and the land portions 33 and 34 in the vehicle width direction outer region is optimized.

  The two-dimensional sipe is a sipe having a straight sipe wall surface in a cross-sectional view perpendicular to the sipe length direction. The three-dimensional sipe is 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.

  Examples of such a three-dimensional sipe include the following (see FIGS. 5 and 6).

  In the three-dimensional sipe shown in FIG. 5, 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 outer side of a 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. 6, the sipe wall surface has a structure in which a plurality of prisms 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.

[Others]
In the pneumatic tire 1, the groove widths W1 to W4 and the distances DE and D1 to D4 are measured in a state in which the tire is mounted on a specified rim and applied with a specified internal pressure and is not loaded. .

  The specified rim is 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” specified by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or “INFLATION PRESSURES” specified by ETRTO. The specified load means “maximum load capacity” defined in JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined in TRA, or “LOAD CAPACITY” defined in 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.

[effect]
As described above, the pneumatic tire 1 includes three circumferential main grooves 21 to 23 extending in the tire circumferential direction, and four land portions defined by the circumferential main grooves 21 to 23. 31 to 34 are provided in the tread portion (see FIG. 2). In the pneumatic tire 1, the ground contact width of the first land portion 31 in one tread portion shoulder region is wider than the ground contact width of the fourth land portion 34 in the other tread portion shoulder region. Further, the first land portion 31 having a wide contact width extends in the tire width direction from the outer side of the tire contact surface and communicates with the inclined grooves 311. A plurality of first lug grooves 312 and a plurality of second lug grooves 313 extending in the tire width direction and connecting the inclined groove 311 and the first circumferential main groove 21 are provided. Also, three or more and six or less first lug grooves 312 communicate with one inclined groove 311.

  In such a configuration, one shoulder land portion (first land portion 31) has a wide structure, and the land portion includes a plurality of inclined grooves 311, a plurality of first lug grooves 312, and a plurality of second lug grooves 313. The rigidity of this wide land part is reduced, and the drainage of the land part is ensured. Furthermore, when three or more first lug grooves 312 communicate with one inclined groove 311, the drainage performance and snow traction performance of the land portion are improved. By these, there exists an advantage which can make dry performance, wet performance, and snow performance of a tire compatible.

  In the pneumatic tire 1, the arrangement intervals P2_a to P2_c of the second lug grooves 313_a to 313_c are narrower than the arrangement intervals P1_a and P1_b of the first lug grooves 312_a and 312_b (see FIG. 3). Thereby, the drainage property and snow traction property of the 1st land part 31 improve, and there exists an advantage which the wet performance and snow performance of a tire improve.

  Moreover, in this pneumatic tire 1, the inclination angle θ of the inclined groove 311 is in the range of 10 [deg] ≦ θ ≦ 40 [deg] (see FIG. 3). In such a configuration, since the inclination angle θ of the inclined groove 311 is optimized, there is an advantage that the snow performance and wet performance of the tire are improved. For example, θ <10 [deg] is not preferable because the edge component of the inclined groove becomes small and the effect of improving snow performance is difficult to obtain. On the other hand, when 40 [deg] <θ, the drainage performance of the inclined groove is lowered, and it is difficult to obtain the effect of improving the wet performance.

  Further, in the pneumatic tire 1, all or some of the plurality of second lug grooves 313_a to 313_c each have a bottom upper portion 316 that raises the groove bottom (see FIG. 3). ). In such a configuration, since the bottom upper part 316 reinforces the rigidity of the land portion 31, there is an advantage that the dry performance of the tire is improved.

  In the pneumatic tire 1, the groove width W4 of the second lug grooves 313_a to 313_c is in the range of 2 [mm] ≦ W4 ≦ 6 [mm] (see FIG. 3). In such a configuration, since the groove width W4 of the second lug grooves 313_a to 313_c is optimized, there is an advantage that both the dry performance and the snow performance of the tire are compatible. For example, W4 <2 [mm] is not preferable because the traction of the second lug groove is lowered and it is difficult to obtain an effect of improving snow performance. Further, when 6 [mm] <W4 is satisfied, the rigidity of the land portion is lowered, and it is difficult to obtain the effect of improving the dry performance.

  Moreover, in this pneumatic tire 1, the two land parts (the 2nd land part 32 and the 3rd land part 33) in a tread part center area | region are several lugs which penetrate each land part 32 and 33 to a tire width direction. Each of the lug grooves 321, 331 has a bottom upper portion 323, 333 that raises the groove bottom (see FIG. 4). In such a configuration, since the bottom upper portions 323 and 333 reinforce the rigidity of the land portions 32 and 33, there is an advantage that the dry performance of the tire is improved.

  Further, in the pneumatic tire 1, a circumferential main that defines a distance DE to the tire contact point EL with respect to the tire equator line CL and a land portion (first land portion 31) in one shoulder region of the tread portion. Distance D1 to the groove (first circumferential main groove 21) and the circumferential main groove (third circumferential main groove 23) that divides the land portion (fourth land portion 34) in the shoulder region of the other tread portion The distance D3 has a relationship of 0.10 ≦ D1 / DE ≦ 0.30 and 0.55 ≦ D3 / DE ≦ 0.75 (see FIG. 2). At this time, it is assumed that the left and right circumferential main grooves (the first circumferential main groove 21 and the third circumferential main groove 23) are arranged with the tire equator line CL interposed therebetween. In such a configuration, since the relationship between the contact widths of the left and right shoulder land portions (the first land portion 31 and the fourth land portion 34) is optimized, the advantage that the dry performance, the wet performance, and the snow performance of the tire can be properly balanced. There is. For example, if D1 / DE <0.10, the ground contact width of the shoulder land portion (first land portion 31) having the inclined groove 311 becomes narrow, and it is difficult to obtain an effect of improving snow performance, which is not preferable. Further, if 0.30 <D1 / DE, the ground contact width of the center land portion (second land portion 32) becomes narrow, and it is difficult to obtain the effect of improving the dry performance, which is not preferable. Further, when D3 / DE <0.55, the ground contact width of the shoulder land portion (fourth land portion 34) becomes narrow, and it is difficult to obtain the effect of improving snow performance. Further, when 0.75 <D3 / DE, the drainage of the circumferential main groove (third circumferential main groove 23) during turning of the vehicle is lowered, and it is difficult to obtain the effect of improving the wet performance. .

  Further, in the pneumatic tire 1, a land portion (first land portion 31) having a wide contact width is disposed between the inclined groove 311 and the tire contact end EL and extends in the tire circumferential direction. It has a shallow groove 24 (see FIG. 3). Further, the groove width W2 and the groove depth H2 of the circumferential thin shallow groove 24 are in the range of 2 [mm] ≦ W2 ≦ 4 [mm] and 2 [mm] ≦ H2 ≦ 4 [mm]. In such a configuration, there is an advantage that the snow traction is increased by the edge component of the circumferential narrow groove 24 and the snow performance of the tire is improved. If W2 <2 [mm], the effect of improving snow performance is difficult to obtain, which is not preferable. Further, when 4 [mm] <W2, it is not preferable because the rigidity of the land portion is lowered and it is difficult to obtain the effect of improving the dry performance. Further, when H2 <2 [mm], it is difficult to obtain the effect of improving snow performance, which is not preferable. Further, when 4 [mm] <H2, it is not preferable because the rigidity of the land portion is lowered and it is difficult to obtain the effect of improving the dry performance.

  Moreover, in this pneumatic tire 1, two land portions (first land portion 31 and second land portion 32) in the tread region on the land portion (first land portion 31) side having a wide contact width are two-dimensional sipe. Two land portions (the third land portion 33 and the fourth land portion 34) having 317 and 324 and in the other tread region have three-dimensional sipes 334 and 343 (see FIG. 2). When turning on a dry road, a large contact pressure acts on the tread region on the outer side in the vehicle width direction. Therefore, when the pneumatic tire 1 is mounted on the vehicle with the tread region side having the two-dimensional sipes 317 and 324 as the inner side in the vehicle width direction and the tread region side having the three-dimensional sipes 334 and 343 as the outer side in the vehicle width direction. The rigidity of the land portions 33 and 34 is ensured by the three-dimensional sipes 334 and 343 in the tread region on the outer side in the vehicle width direction. Thereby, there exists an advantage which the dry performance of a tire improves. On the other hand, in the tread region on the inner side in the vehicle width direction, snow traction is ensured by the two-dimensional sipes 317 and 324. Thereby, there exists an advantage which the snow performance of a tire improves. Such a sipe arrangement is particularly useful when the pneumatic tire 1 is mounted on a vehicle having a negative camber.

  In addition, the pneumatic tire 1 has a designation to be mounted on the vehicle with the land portion (first land portion 31) having a wide ground contact width inward in the vehicle width direction (not shown). 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, when the pneumatic tire 1 is mounted on the vehicle with the land portion (first land portion 31) having a wide contact width on the inner side in the vehicle width direction (see FIG. 2), snow traction is effectively improved. . Thereby, there exists an advantage which the snow performance of a tire improves.

  FIG. 7 is a table showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention. FIG. 8 is a plan view of a tread showing a conventional pneumatic tire.

  In this example, (1) dry performance, (2) wet performance, and (3) snow performance were evaluated for a plurality of different pneumatic tires (see FIG. 7). In these performance tests, a pneumatic tire with a tire size of 255 / 40R19 is assembled to a rim with a rim size of 19 × 8.5J, and the pneumatic tire is given a pneumatic pressure of 250 [kPa] and a maximum load capacity specified by JATMA. . As a test vehicle, a sedan of a four-wheel drive vehicle having a displacement of 3.0 [L] is used.

  (1) In the evaluation of dry performance, a test vehicle equipped with pneumatic tires travels on a dry road handling course, and a specialized test driver performs sensory evaluation on steering stability performance in a speed range of 200 km / h or less. I do. 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 on wet performance, a test vehicle equipped with a pneumatic tire travels on a predetermined handling course with a constant water depth, and a specialized test driver performs sensory evaluation on the steering stability performance. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the value, the better.

  (3) In the evaluation on snow performance, a test vehicle equipped with a pneumatic tire travels on a predetermined snow handling course, and a specialized test driver performs sensory evaluation on the steering stability performance. 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. Specifically, the pneumatic tire 1 includes three circumferential main grooves 21 to 23 and four land portions 31 to 34 in the tread portion, and the ground contact width of the first land portion 31 is that of the fourth land portion 34. It is wider than the ground contact width (see FIG. 2). The groove width W1 of the first circumferential main groove 21 is W1 = 16 [mm] (see FIG. 3). The first land portion 31 includes an inclined groove 311, a first lug groove 312 and a second lug groove 313. Further, three first lug grooves 312 communicate with one inclined groove 311. In addition, four second lug grooves 313 are arranged with respect to the three first lug grooves 312. Moreover, two types of 2nd lug grooves 313_b and 313_c of 3 types of 2nd lug grooves 313_a-313_c have the bottom upper part 316, respectively. Further, the first land portion 31 has a circumferential thin shallow groove 24 between the inclined groove 311 and the tire ground contact end EL. The pneumatic tire 1 is mounted on the test vehicle with the first land portion 31 side in the vehicle width direction. The first land portion 31 and the second land portion 32 in the inner region in the vehicle width direction have a plurality of two-dimensional sipes 317 and 324, and the third land portion 33 and the fourth land portion in the outer region in the vehicle width direction. The land portion 34 has a plurality of three-dimensional sipes 334 and 343. Moreover, the 2nd land part 32, the 3rd land part 33, and the 4th land part 34 are all a block row by having a penetration lug groove.

  The pneumatic tire 1 of Examples 2-12 has the structure which changed a part of the pneumatic tire 1 of Example 1. FIG.

  The conventional pneumatic tire has the configuration shown in FIG.

  As shown in the test results, in the pneumatic tires 1 of Examples 1 to 12, it is understood that the dry performance, wet performance and snow performance of the tire are compatible as compared with the conventional pneumatic tire (see FIG. 7). ). Further, when comparing Examples 1 to 3, the arrangement intervals P2_a to P2_c of the second lug grooves 313_a to 313_c are narrow (the ratio between the second lug grooves 313_a to 313_c and the number of the first lug grooves 312_a and 312_b is small). It turns out that the wet performance and snow performance of a tire improve by setting. Further, when Examples 1, 4, and 5 are compared, it is understood that the snow performance and wet performance of the tire are improved by optimizing the inclination angle θ of the inclined groove 311. Further, when comparing Examples 1 and 6, the second lug grooves 313_b and 313_c of the first land portion 31, the lug grooves 321 of the second land portion 32 and the lug grooves 331 of the third land portion 33, It can be seen that the tires 323 and 333 are arranged to improve the dry performance of the tire.

  In addition, when Examples 1, 7, and 8 are compared, the dry performance and the snow performance of the tire can be compatible by optimizing the groove width W4 of the second lug grooves 313_a to 313_c of the first land portion 31. I understand. Further, when Examples 1, 9, and 10 are compared, the relationship between the contact widths of the left and right shoulder land portions (the first land portion 31 and the fourth land portion 34) is optimized, so that the tire dry performance and wetness are improved. It turns out that performance and snow performance are compatible. Moreover, when Examples 1 and 11 are compared, it can be seen that the snow performance of the tire is improved by the first land portion 31 having the circumferentially shallow shallow groove 24. Moreover, when Examples 1 and 12 are compared, it can be seen that the dry performance and the snow performance of the tire are improved by appropriately using the two-dimensional sipe and the three-dimensional sipe.

  DESCRIPTION OF SYMBOLS 1 Pneumatic tire, 11 Bead core, 12 Bead filler, 13 Carcass layer, 14 Belt layer, 141, 142 Belt ply, 15 Tread rubber, 16 Side wall rubber, 21 1st circumferential main groove, 22 2nd circumferential main groove , 23 3rd circumferential direction main groove, 24 circumferential direction shallow shallow groove, 31 1st land part, 311 inclined groove, 312 1st lug groove, 313 2nd lug groove, 314, 315 block, 316 bottom upper part, 317 2D Sipe, 32 Second Land, 321 Lag Groove, 322 Block, 323 Upper Bottom, 324 2D Sipe, 33 Third Land, 331 Lag Groove, 332 Block, 333 Upper Bottom, 334 3D Sipe, 34 Fourth Land Part, 341 lug groove, 342 block, 343 three-dimensional sipe

Claims (10)

A pneumatic tire provided with a tread portion including three circumferential main grooves extending in the tire circumferential direction and four land portions defined by the three circumferential main grooves,
The contact width of the land portion in one tread shoulder region is wider than the contact width of the land portion in the other tread shoulder region,
A plurality of inclined grooves in which the land portion having a wide contact width is inclined with respect to the tire circumferential direction, and a plurality of first lug grooves that extend from the outside of the tire contact surface in the tire width direction and communicate with the inclined grooves. And a plurality of second lug grooves extending in the tire width direction and connecting the inclined groove and the circumferential main groove, and
The pneumatic tire is characterized in that three or more and six or less first lug grooves communicate with one inclined groove.   The pneumatic tire according to claim 1, wherein an arrangement interval of the second lug grooves is narrower than an arrangement interval of the first lug grooves.   3. The pneumatic tire according to claim 1, wherein an inclination angle θ of the inclined groove is in a range of 10 [deg] ≦ θ ≦ 40 [deg].   The pneumatic tire according to any one of claims 1 to 3, wherein all or some of the plurality of second lug grooves each have a bottom upper portion that raises the bottom of the groove.   The pneumatic tire according to any one of claims 1 to 4, wherein a groove width W4 of the second lug groove is in a range of 2 [mm] ≤ W4 ≤ 6 [mm].   The two land portions in the center region of the tread portion each have a plurality of lug grooves penetrating the land portion in the tire width direction, and all or some of the plurality of lug grooves are The pneumatic tire as described in any one of Claims 1-5 which each has the bottom upper part which raises a groove bottom.   The distance DE to the tire ground contact edge with respect to the tire equator line, the distance D1 to the circumferential main groove that divides the land portion in one tread shoulder region, and the land in the other tread shoulder region The distance D3 to the circumferential main groove that divides the portion has a relationship of 0.10 ≦ D1 / DE ≦ 0.30 and 0.55 ≦ D3 / DE ≦ 0.75. The pneumatic tire according to one.   The land portion having a wide contact width has a circumferential shallow groove extending between the inclined groove and the tire contact end and extending in the tire circumferential direction, and the circumferential narrow groove groove. The width W2 and the groove depth H2 are in a range of 2 [mm] ≦ W2 ≦ 4 [mm] and 2 [mm] ≦ H2 ≦ 4 [mm], according to any one of claims 1 to 7. Pneumatic tire.   The two land portions in the tread region on the land portion side having a wide contact width have two-dimensional sipes, and the two land portions in the other tread region have three-dimensional sipes. The pneumatic tire according to any one of 8.   The pneumatic tire according to any one of claims 1 to 9, wherein the pneumatic tire has a designation to be mounted on a vehicle with the land portion having a wide ground contact width inward in the vehicle width direction.

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