JP6369602B1 - Pneumatic tire - Google Patents

Abstract

A pneumatic tire capable of improving uneven wear resistance and extending a wear life. A rib 20 having at least one end in a tire width direction defined by a circumferential main groove 10, and a circumferential sipe 30 extending in the tire circumferential direction and formed in the rib 20 at a distance from each other in the tire circumferential direction. A plurality of ribs 20 are formed in the rib 20 side by side in the tire circumferential direction, one end terminates in the rib 20 and the other end opens in the circumferential main groove 10, and extends in the tire circumferential direction. A plurality of first shallow grooves 40 formed at a groove depth shallower than the depths of the circumferential sipe 30 and the rib edge sipe 35 and connected at both ends to the circumferential sipe 30 adjacent in the tire circumferential direction, and the circumferential sipe 30 and a plurality of second narrow grooves 45 having one end connected to the first narrow groove 40 and the other end connected to the rib edge sipe 35. , Comprising a. [Selection] Figure 2

Description

  The present invention relates to a pneumatic tire.

  In the pneumatic tire, grooves are formed on the tread surface mainly in order to ensure drainage, but the arrangement form of the grooves is also related to the wear characteristics of the tread surface. For this reason, some conventional pneumatic tires have improved wear characteristics by devising the arrangement of grooves. For example, in the pneumatic tire described in Patent Document 1, a zigzag narrow groove is formed in a rib sandwiched between main grooves extending in the tire circumferential direction, and a sipe is formed at the groove bottom of the bent portion of the narrow groove. Thus, even if wear progresses, the skid resistance and uneven wear resistance are ensured.

JP 2017-7476 A

  Here, in vehicles that often run continuously at a relatively high speed, after wearing a new pneumatic tire and starting to use, if uneven wear occurred in the initial stage of use, uneven wear occurred Pneumatic tires may be removed early. In other words, the uneven wear that occurred in the initial stage after the start of use of a new product is related to the subsequent uneven wear and the life of the pneumatic tire due to the wear. In tires, it is important to suppress uneven wear at the initial stage of use from a new article.

  However, when the pneumatic tire is new, the depth of the groove formed on the tread surface is deep, so that when the tread surface contacts the road surface, the land portion defined by the groove is likely to fall down greatly. For this reason, when the pneumatic tire is new, uneven wear is likely to occur due to the land part falling down greatly. In this way, uneven wear is likely to occur in the initial stage of use of the pneumatic tire, and therefore, uneven wear due to uneven wear in the initial use is suppressed by suppressing uneven wear in the initial use of the pneumatic tire. It has been very difficult to suppress and extend the life of pneumatic tires due to wear.

  The present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire capable of improving uneven wear resistance and extending the wear life.

  In order to solve the above-described problems and achieve the object, a pneumatic tire according to the present invention is divided by a plurality of circumferential main grooves extending in the tire circumferential direction and at least one end side in the tire width direction by the circumferential main grooves. A plurality of ribs extending in the tire circumferential direction, spaced apart in the tire circumferential direction and formed in the ribs, and formed in the rib side by side in the tire circumferential direction. Rib edge sipe that terminates in the rib and the other end opens in the circumferential main groove, and extends in the tire circumferential direction, and is formed with a groove depth shallower than the depth of the circumferential sipe and the rib edge sipe, A plurality of first narrow grooves whose both ends are connected to the circumferential sipe adjacent in the tire circumferential direction, and a groove depth shallower than the circumferential sipe and the rib edge sipe. Connected to said first narrow shallow groove, the other end characterized in that it comprises a plurality of second fine shallow grooves which are connected to the rib edge sipes.

In the pneumatic tire, the first narrow shallow groove is preferably the maximum groove depth _{D N1} is in the range of 0.5mm ≦ _{D N1} ≦ 4.0mm.

In the pneumatic tire, the second narrow shallow groove is preferably the maximum groove depth _{D N2} is in the range of 0.5mm ≦ _{D N2} ≦ 4.0mm.

In the pneumatic tire, the circumferential sipe has a maximum depth D _SC of the circumferential sipe, the relationship between the maximum groove depth D of the circumferential main _{groove, 0.50 ≦ (D SC / D} ) It is preferable to be within the range of ≦ 0.80.

In the pneumatic tire, the rib edge sipe, and the maximum depth D _SE of the rib edge sipes, the relationship between the maximum groove depth D of the circumferential main _{groove, 0.60 ≦ (D SE / D} ) It is preferable to be within the range of ≦ 0.90.

  In the pneumatic tire, the second narrow groove is a tire from a front side in a tire rotation direction from an end side connected to the first shallow groove toward an end side connected to the rib edge sipe. It is preferable to incline with respect to the tire width direction in the direction toward the rear side in the rotation direction.

  In the pneumatic tire described above, the rib edge sipe extends from the front side in the tire rotation direction to the rear side in the tire rotation direction from the end side on the side terminating in the rib toward the end side opening in the circumferential main groove. It is preferable to incline with respect to the tire width direction in the direction toward the side.

In the pneumatic tire, wherein the circumferential sipes and the first narrow shallow groove, the length L _SC in the tire circumferential direction of the circumferential sipe, the length in the tire circumferential direction of the first narrow shallow groove L _N1 Is preferably within the range of 0.4 ≦ (L _N1 / L _SC ) ≦ 0.8.

  The pneumatic tire according to the present invention has the effect of improving uneven wear resistance and extending the wear life.

FIG. 1 is a plan view showing a tread surface of a pneumatic tire according to an embodiment. FIG. 2 is a detailed view of part A of FIG. FIG. 3 is a detailed view of part B of FIG. FIG. 4 is an explanatory diagram of the circumferential sipe and the first shallow groove in the CC direction view of FIG. 3. FIG. 5 is an explanatory diagram of a rib edge sipe, a second thin shallow groove, and a circumferential main groove when viewed in the EE direction of FIG. 3. 6 is a cross-sectional view taken along line FF in FIG. FIG. 7 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view showing a state in which the circumferential sipe is formed in a linear shape. FIG. 8 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view showing a state in which the rib edge sipes and the second shallow grooves are formed along the tire width direction. FIG. 9 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory diagram illustrating a state in which the positions of the two second shallow grooves connected to the first shallow grooves are the same in the tire circumferential direction. It is. FIG. 10A is a chart showing the results of a performance test of a pneumatic tire. FIG. 10B is a chart showing the results of a performance test of a pneumatic tire. FIG. 10C is a chart showing the results of a performance test of a pneumatic tire.

  Hereinafter, an embodiment of a pneumatic tire according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be replaced by those skilled in the art and can be easily conceived, or substantially the same.

  In the following description, the tire width direction means a direction parallel to the rotation axis of the pneumatic tire, the inner side in the tire width direction means the direction toward the tire equator line in the tire width direction, and the outer side in the tire width direction means the tire width. The direction opposite to the direction toward the tire equator line. Further, the tire radial direction means a direction orthogonal to the tire rotation axis, and the tire circumferential direction means a direction rotating around the tire rotation axis. The tire equator line is a line along the tire circumferential direction of the pneumatic tire on the tire equator plane, which is a plane orthogonal to the tire rotation axis and passing through the center of the tire width of the pneumatic tire. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane in the tire width direction.

  FIG. 1 is a plan view showing a tread surface 3 of a pneumatic tire 1 according to an embodiment. A pneumatic tire 1 shown in FIG. 1 is provided with a tread portion 2 at the outermost portion in the tire radial direction, and the surface of the tread portion 2, that is, a vehicle on which the pneumatic tire 1 is mounted (not shown). The portion that comes into contact with the road surface during travel is formed as a tread surface 3. A plurality of circumferential main grooves 10 extending in the tire circumferential direction and a plurality of circumferential narrow grooves 15 extending in the tire circumferential direction with a groove width narrower than the groove width of the circumferential main groove 10 are formed on the tread surface 3. Yes. The tread surface 3 is formed with a plurality of ribs 20 that are land portions extending in the tire circumferential direction by the plurality of circumferential main grooves 10 and the plurality of circumferential narrow grooves 15. At least one end side of the rib 20 in the tire width direction is partitioned by the circumferential main groove 10.

  Specifically, four circumferential main grooves 10 are formed side by side in the tire width direction, two center circumferential main grooves 11 positioned on both sides of the tire equator line CL in the tire width direction, and two Two shoulder circumferential main grooves 12 that are adjacent to the center circumferential main groove 11 and are located on the outer sides in the tire width direction of the respective center circumferential main grooves 11 are provided. Further, two circumferential narrow grooves 15 are formed, and the two circumferential narrow grooves 15 are arranged one by one on the outer sides in the tire width direction of the two shoulder circumferential main grooves 12. ing. The circumferential main groove 10 here has a groove width in the range of 4.0 mm to 20.0 mm and a groove depth in the range of 10.0 mm to 28.0 mm. Further, the circumferential narrow groove 15 has a groove width in the range of 1.0 mm to 4.0 mm, and a groove depth in the range of 8.0 mm to 28.0 mm.

  Further, the rib 20 is located between the two center circumferential main grooves 11 and disposed on the tire equator line CL, and the adjacent center circumferential main groove 11 and shoulder circumferential main. A second rib 22 positioned between the groove 12 and a shoulder rib 23 positioned between the adjacent shoulder circumferential main groove 12 and the circumferential narrow groove 15 are provided. That is, the center rib 21 and the second rib 22 are partitioned by the circumferential main groove 10 on both sides in the tire width direction, and the shoulder rib 23 is partitioned by the circumferential main groove 10 on one end side in the tire width direction. .

  Each of the ribs 20 formed as described above has a relatively short length and extends in the tire width direction, with one end terminating in the rib 20 and the other end opened in the circumferential main groove 10 or the circumferential narrow groove 15. Rib edge sipes 35 are formed. That is, the rib edge sipe 35 is located at the end of the rib 20 in the tire width direction, and the tread surface 3 of the rib 20 intersects the groove wall of the circumferential main groove 10 or the groove wall of the circumferential narrow groove 15. Connected to the rib edge 20a. The rib edge sipes 35 of each rib 20 are formed in a linear shape that is inclined in the tire circumferential direction with respect to the tire width direction, and a plurality of rib edge sipes 35 are arranged in the tire circumferential direction on both ends of each rib 20 in the tire width direction. It is arranged by.

  For example, the center rib 21 includes a rib edge sipe 35 positioned on the side of one center circumferential main groove 11 of the two center circumferential main grooves 11 defining the center rib 21 and the other center circumferential main. A rib edge sipe 35 located on the groove 11 side is provided, and each rib edge sipe 35 has one end terminating in the center rib 21 and the other end opened to the center circumferential main groove 11. Further, the second rib 22 is provided with a rib edge sipe 35 located on the center circumferential direction main groove 11 side and a rib edge sipe 35 located on the shoulder circumferential direction main groove 12 side. One end terminates in the second rib 22 and the other end opens into the center circumferential main groove 11 or the shoulder circumferential main groove 12. The shoulder rib 23 is provided with a rib edge sipe 35 positioned on the shoulder circumferential main groove 12 side and a rib edge sipe 35 positioned on the circumferential narrow groove 15 side. One end terminates in the shoulder rib 23 and the other end opens to the shoulder circumferential main groove 12 or the circumferential narrow groove 15.

  Further, among the plurality of ribs 20, the center rib 21 and the second rib 22 are located on the inner side in the tire width direction than the shoulder circumferential main groove 12, and both sides in the tire width direction are partitioned by the circumferential main groove 10. The circumferential sipe 30, the first narrow groove 40, and the second thin groove 45 are formed. The two second ribs 22, the circumferential sipe 30 formed in the center rib 21, the first narrow groove 40, and the second narrow groove 45 are all formed in the same form.

  FIG. 2 is a detailed view of part A of FIG. Regarding the circumferential sipe 30, the rib edge sipe 35, the first narrow groove 40, and the second narrow groove 45, one of the two second ribs 22 and the center rib 21 is representatively used as one second rib 22. explain. Of the circumferential sipe 30, the rib edge sipe 35, the first narrow groove 40, and the second narrow groove 45, the circumferential sipe 30 extends in the tire circumferential direction at a position near the center of the second rib 22 in the tire width direction. A plurality of second ribs 22 are formed while extending in the tire circumferential direction. Each circumferential sipe 30 is bent at two locations near the center in the tire circumferential direction while extending in the tire circumferential direction. That is, the circumferential sipe 30 is bent in a zigzag shape in the tire width direction while extending in the tire circumferential direction, or is formed in a substantially crank shape while extending in the tire circumferential direction. The rib edge sipe 35 is formed to extend in the tire width direction, and is an end portion 35a that is an end portion on the side terminating in the second rib 22, and an opening that is an end portion on the side opening to the circumferential main groove 10. And an end portion 35b.

  The sipe here is formed in a narrow groove shape on the tread surface 3, and the pneumatic tire 1 is assembled with a rim on a normal rim, and a narrow groove is formed when there is no load under normal internal pressure conditions. The wall surfaces do not contact each other, but when the narrow groove is located in the portion of the ground plane formed on the flat plate when loaded in the vertical direction on the flat plate, or when the land part where the narrow groove is formed falls The wall surface which comprises a narrow groove, or at least one part of the site | part provided in a wall surface says what mutually contacts by deformation | transformation of a land part. The circumferential sipe 30 and the rib edge sipe 35 are included in the sipe thus defined.

  The regular rim is “standard rim” defined by JATMA, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO. The normal internal pressure is “maximum air pressure” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO.

  In the present embodiment, the circumferential sipe 30 has a width in the range of 0.3 mm to 0.8 mm and a depth in the range of 7.0 mm to 11.5 mm. The rib edge sipe 35 has a width in the range of 0.3 mm to 0.8 mm and a depth in the range of 8.5 mm to 13.0 mm.

  A plurality of first narrow grooves 40 are formed in the second rib 22, and each first shallow groove 40 extends in the tire circumferential direction and is connected at both ends to a circumferential sipe 30 adjacent in the tire circumferential direction. Has been. That is, the first narrow groove 40 extending in the tire circumferential direction is disposed at a position near the center of the second rib 22 in the tire width direction, like the circumferential sipe 30, and an end portion 40a in the tire circumferential direction is The circumferential sipe 30 extending in the tire circumferential direction is connected to an end 30a in the tire circumferential direction. Further, the first shallow groove 40 extends in the tire circumferential direction according to the circumferential sipe 30 that is inclined with respect to the tire circumferential direction by extending in the tire circumferential direction in a zigzag shape, and at least the vicinity of the end portion 40a is, The tire is inclined in the tire width direction with respect to the tire circumferential direction in accordance with the circumferential sipe 30.

  The first shallow grooves 40 are disposed in a portion between all the circumferential sipes 30 that are separated from each other in the tire circumferential direction and are adjacent to each other in the tire circumferential direction. The end portions 40a are respectively connected to the end portions 30a of the circumferential sipe 30 located on both sides of the first narrow groove 40 in the circumferential direction. The first narrow shallow groove 40 thus formed is formed with a groove width wider than the width of the circumferential sipe 30 and the rib edge sipe 35, and the groove depth is the circumferential sipe 30 and the rib edge sipe 35. The groove depth is shallower than the depth of the groove.

Moreover, the circumferential sipe 30 and the first Hosoasamizo 40, the length L _SC in the tire circumferential direction of the circumferential sipe 30, the relationship between the length L _N1 in the tire circumferential direction of the first Hosoasamizo 40 0.4 ≦ (L _N1 / L _SC ) ≦ 0.8. In addition, although the circumferential direction sipe 30 and the 1st thin shallow groove | channel 40 are each provided with two or more, the circumferential length sipe 30 and the 1st thin shallow groove | channel 40 may not be the same length. The circumferential sipe 30 and the first Hosoasamizo 40, relations and of circumferential sipe 30 between the length L _SC, regardless relationship between the first Hosoasamizo 40 length between L _N1, are connected to each other The relationship between the lengths L _SC and L _N1 in the tire circumferential direction between the circumferential sipe 30 and the first narrow shallow groove 40 is within a range of 0.4 ≦ (L _N1 / L _SC ) ≦ 0.8. That's fine.

  A plurality of the second narrow grooves 45 are formed in the second rib 22 and are formed on both sides of the first shallow grooves 40 in the tire width direction so as to extend in the tire width direction. Specifically, one second narrow groove 45 is provided on each side of each first narrow groove 40 in the tire width direction. For this reason, two first thin shallow grooves 40 are connected to two first thin shallow grooves 45. The second narrow groove 45 disposed on both sides of the first narrow groove 40 in the tire width direction is formed from the first narrow groove 40 to the rib edge sipe 35, and one end thereof is the first narrow groove 40. And the other end is connected to the rib edge sipe 35. That is, the second shallow shallow groove 45 includes an inner connection portion 45a which is an end portion on the side connected to the first thin shallow groove 40 and an outer connection portion 45b which is an end portion on the side connected to the rib edge sipe 35. And have. The inner connection portion 45a is an end portion located on the center side in the width direction of the second rib 22 among both end portions of the second shallow groove 45 extending in the tire width direction, and the outer connection portion 45b is the second connection portion 45b. Of the both ends of the thin shallow groove 45, the end is located on the rib edge 20 a side in the width direction of the second rib 22.

  The two second shallow grooves 45 connected to one first shallow groove 40 are arranged at different positions in the tire circumferential direction, that is, in one first shallow groove 40. The two second thin shallow grooves 45 to be connected are disposed offset in the tire circumferential direction. In other words, the plurality of second thin shallow grooves 45 are positions where the inner connecting portions 45a in the tire circumferential direction are the second thin shallow grooves 45 disposed on both sides in the tire width direction of the first thin shallow grooves 40. Offset in the tire circumferential direction.

  Further, the second shallow groove 45 extends in the tire width direction in accordance with the rib edge sipe 35 inclined with respect to the tire width direction, and at least the vicinity of the outer connection portion 45b connected to the rib edge sipe 35 is a rib. Inclined in the tire circumferential direction with respect to the tire width direction in accordance with the edge sipe 35. In the present embodiment, the second thin shallow groove 45 is bent in the vicinity of the inner connecting portion 45 a connected to the first thin shallow groove 40, so that most of the second thin shallow groove 45 is formed by the rib edge sipe 35. It is inclined at almost the same angle as the inclination angle.

  Of both ends of the second shallow groove 45, the inner connection portion 45 a that is the end connected to the first shallow groove 40 is connected to a position different from the end 40 a of the first shallow groove 40. ing. Therefore, the two second shallow grooves 45 connected to one first shallow groove 40 are located at different positions in the tire circumferential direction between both end portions 40a of the first shallow groove 40. Further, the inner connection portion 45a is connected. The relative relationship between the positions of the two second shallow grooves 45 connected to the first shallow grooves 40 in the tire circumferential direction is the same in the plurality of first shallow grooves 40. For example, in FIG. 2, the second thin shallow groove 45 connected to the first thin shallow groove 40 from the left side is more than the second thin shallow groove 45 connected to the first thin shallow groove 40 from the right side. The position of the two second shallow grooves 45 connected to the same first shallow groove 40 in the tire circumferential direction also in the first shallow groove 40 (not shown) that is located on the upper side of the paper surface. The relative relationships of are all the same.

  In addition, the outer connecting portion 45b, which is the end portion of the second narrow groove 45 on the side connected to the rib edge sipe 35, is the rib edge sipe 35 of the plurality of rib edge sipes 35 arranged in the tire circumferential direction. Connected to the terminal end 35a. In other words, the rib edge sipes 35 are formed on both sides of the second rib 22 in the tire width direction, and thus are disposed on both sides of the first shallow groove 40 in the tire width direction, like the second shallow groove 45. Therefore, the second narrow shallow grooves 45 are respectively connected to the rib edge sipes 35 in which the side in the tire width direction with the first thin shallow grooves 40 as a boundary is located on the same side. The second shallow groove 45 formed in this manner is formed with a groove width wider than the width of the circumferential sipe 30 and the rib edge sipe 35, as in the first thin groove 40, and the groove depth. Is formed with a groove depth shallower than the depth of the circumferential sipe 30 and the rib edge sipe 35.

Rib edge sipes 35 formed at both ends in the tire width direction of the second ribs 22, a length _{W SE} in the tire width direction, the width _{W R} of each of the ribs _{20, 0.05 ≦ (W SE /} W _{R 1} ) ≦ 0.25. Further, in the rib edge sipes 35 that are arranged in the tire circumferential direction, the distance L _SE in the tire circumferential direction between the open end portions 35b of the rib edge sipes 35 that are adjacent in the tire circumferential direction is the second fineness that is adjacent in the tire circumferential direction. The relationship between the shallow grooves 45 and the pitch P _N2 in the tire circumferential direction is in a range of 2.5 ≦ (P _N2 / L _SE ) ≦ 7.5. Note that the second Hosoasamizo 45 between the pitch P _N2 of adjacent in the tire circumferential direction is preferably an integral multiple of the distance L _SE in the tire circumferential direction of the open end 35b between the ribs edge sipes 35.

Further, the offset amount L _N2 in the tire circumferential direction between the inner connection portions 45a of the two second thin shallow grooves 45 connected to the same first thin shallow groove 40 is determined by the rib edge sipes 35 adjacent to each other in the tire circumferential direction. relationship between the distance _{L SE} in the tire circumferential direction between the opening end portion 35b has been in a range of _{0.5 ≦ (L N2 / L SE} ) ≦ 2.0. Further, the offset amount L _N2 between the inner connecting portions 45a of the second narrow shallow grooves 45 has a relationship with the length L _SC of the circumferential sipe 30 in the tire circumferential direction: 0.1 ≦ (L _N2 / L _SC ) It is within the range of ≦ 0.6. Further, the length L _N1 of the first thin shallow groove 40 in the tire circumferential direction and the inner connection portions 45a of the two second thin shallow grooves 45 connected to the first thin shallow groove 40 in the tire circumferential direction. The relationship with the offset amount L _N2 is in the range of 0.3 ≦ (L _N2 / L _N1 ) ≦ 0.7.

In this case, the offset amount L _N2 between the inner connection portions 45a is the inner connection portion having the closest distance in the tire circumferential direction among the inner connection portions 45a of the second shallow grooves 45 having different positions in the tire circumferential direction. It is the distance in the tire circumferential direction between 45a. Further, the offset amount L _N2 in the tire circumferential direction between the inner connection portions 45a of the second shallow grooves 45, and the distance L _SE in the tire circumferential direction between the open end portions 35b of the rib edge sipes 35 adjacent in the tire circumferential direction, Is preferably in the range of 0.8 ≦ (L _N2 / L _SE ) ≦ 1.5. The relationship between the offset amount L _N2 in the tire circumferential direction between the inner connecting portions 45a of the second shallow grooves 45 and the length L _SC in the tire circumferential direction of the circumferential sipe 30 is 0.2 ≦ (L _N2 / L _SC ) ≦ 0.5 is preferable.

  In the second rib 22, the circumferential sipe 30, the rib edge sipe 35, the first narrow groove 40, and the second narrow groove 45 are formed as described above. A plurality of portions 25 are formed. In other words, the position of the second rib 22 near the tread surface 3 is divided into a plurality of block portions 25 by the circumferential sipe 30, the rib edge sipe 35, the first narrow groove 40, and the second thin groove 45. ing. The block portion 25 has one end side in the tire width direction defined by the circumferential sipe 30 and the first shallow groove 40, and the other end side in the tire width direction defined by the circumferential main groove 10, and both sides in the tire circumferential direction. Are partitioned by the rib edge sipe 35 and the second narrow groove 45, thereby forming a shape close to a rectangle.

  A plurality of the block portions 25 are formed side by side in the tire circumferential direction on both sides of the circumferential sipe 30 and the first narrow groove 40 in the tire width direction. In addition, the block portion 25 has the circumferential sipe 30 and the first narrow groove 45 as the positions of the two second thin shallow grooves 45 connected to the same first shallow groove 40 in the tire circumferential direction are different from each other. The block portions 25 on both sides of the shallow groove 40 in the tire width direction are different from each other in the tire circumferential direction, and are offset from each other in the tire circumferential direction. That is, the plurality of block portions 25 arranged side by side in the tire circumferential direction on one side in the tire width direction of the circumferential sipe 30 and the first narrow shallow groove 40, and arranged in the tire circumferential direction on the other side in the tire width direction. The plurality of block portions 25 arranged in the above are arranged so that their positions in the tire circumferential direction are shifted from each other in the tire circumferential direction as a whole.

  Further, in the block portion 25, the corner portions 26 located on the circumferential sipe 30 and the first thin shallow groove 40 side are all partitioned by the first thin shallow groove 40 and the second thin shallow groove 45. That is, on the side of the block portion 25 where the circumferential sipe 30 and the first shallow groove 40 are located in the tire width direction, the second narrow groove 45 is not connected to the circumferential sipe 30, and the second shallow groove. 45 is connected only to the first narrow groove 40. Therefore, on the side of the block portion 25 where the circumferential sipe 30 and the first narrow groove 40 are located, the corner portions 26 are all defined by the first shallow groove 40 and the second thin groove 45. The position where the first shallow groove 40 and the second narrow groove 45 intersect is the corner portion 26 of the block portion 25.

FIG. 3 is a detailed view of part B of FIG. FIG. 4 is an explanatory diagram of the circumferential sipe 30 and the first thin shallow groove 40 in the CC direction view of FIG. 3. FIG. 5 is an explanatory diagram of the rib edge sipe 35, the second thin shallow groove 45, and the circumferential main groove 10 when viewed in the EE direction of FIG. The first narrow groove 40 having a groove width wider than the circumferential sipe 30 and rib edge sipe 35 and a groove depth shallower than the circumferential sipe 30 and rib edge sipe 35 has a groove width W _N1 . It is in the range of 0.5 mm ≦ W _N1 ≦ 2.0 mm, and the maximum groove depth DN ₁ is in the range of 0.5 mm ≦ D _N1 ≦ 4.0 mm. Similarly, the second narrow groove 45 whose groove width is wider than the circumferential sipe 30 and rib edge sipe 35 and whose groove depth is shallower than the circumferential sipe 30 and rib edge sipe 35 has a groove width W _N2. However, it is in the range of 0.5 mm ≦ W _N2 ≦ 2.0 mm, and the maximum groove depth DN ₂ is in the range of 0.5 mm ≦ D _N2 ≦ 4.0 mm. The groove width W _N2 of the groove width W _N1 and second Hosoasamizo 45 of these first Hosoasamizo 40 is adapted to the width of approximately the same size, the maximum groove depth of the first Hosoasamizo 40 D _N1 and the maximum groove depth D _N2 of the second Hosoasamizo 45 is substantially the same size depth.

Incidentally, the maximum groove depth _{D N1} of the first Hosoasamizo 40 maximum groove depth _{D N2} of the second Hosoasamizo 45, 0.5mm ≦ _{D N1} ≦ 2.5mm respectively, 0.5 mm ≦ _{D N2} ≦ More preferably, it is in the range of 2.5 mm.

Further, the circumferential sipe 30 and the rib edge sipe 35 are both shallower than the depth of the circumferential main groove 10 such as the center circumferential main groove 11. Specifically, the circumferential sipe 30, the maximum and the depth _{D SC} of the circumferential sipe 30, the relationship between the maximum groove depth D of the circumferential main groove _{10, 0.50 ≦ (D SC /} D) ≦ It is within the range of 0.80. Further, the rib edge sipes 35, rib and maximum depth _{D SE} edge sipe 35, the relationship between the maximum groove depth D of the circumferential main groove 10, 0.60 ≦ _(D SE /D)≦0.90 It is within the range.

The maximum depth _{D SC} of the circumferential sipe 30 with respect to the maximum groove depth D of the circumferential main groove 10, that is in the range of 0.60 ≦ _(D SC /D)≦0.70, more preferably . The maximum depth _{D SE} rib edge sipes 35 with respect to the maximum groove depth D of the circumferential main groove 10, that is in the range of 0.70 ≦ _(D SE /D)≦0.80, more preferably .

  Moreover, the pneumatic tire 1 according to the present embodiment is a pneumatic tire 1 in which the rotation direction when the vehicle is mounted is designated. The rotation direction specified in this case is a direction in which the pneumatic tire 1 rotates when the vehicle on which the pneumatic tire 1 is mounted moves forward. In the following description, the front side in the tire rotation direction is the rotation direction side when the pneumatic tire 1 is rotated in the designated direction, and the pneumatic tire 1 is mounted on the vehicle and rotated in the designated direction to travel. In some cases, it is the side that contacts the road surface first or leaves the road surface first. The rear side in the tire rotation direction is the opposite side to the rotation direction when the pneumatic tire 1 is rotated in the designated direction, and the pneumatic tire 1 is mounted on the vehicle and rotated in the designated direction to travel. In some cases, it is the side that comes in contact with the road surface later or leaves the road surface later.

  The second shallow groove 45 is inclined with respect to the tire width direction in the direction from the front side in the tire rotation direction toward the rear side in the tire rotation direction from the inner connection portion 45a side to the outer connection portion 45b side. . That is, in the second shallow groove 45, an angle α formed by a rear portion in the tire rotation direction with respect to the tire circumferential direction is an acute angle.

  In the present embodiment, the second thin shallow groove 45 is bent in the vicinity of the inner connection portion 45a. In this case, the angle α of the second thin shallow groove 45 is the both end portions of the second thin shallow groove 45. It is the angle of the straight line 48 which connects. That is, the straight line 48 is a straight line connecting the inner connection part 45 a and the outer connection part 45 b, and the angle of the straight line 48 with respect to the tire circumferential direction is used as the angle of the second thin shallow groove 45. In other words, since the second thin shallow groove 45 is formed by bending, a straight line 48 connecting both ends indicates the extending direction of the second thin shallow groove 45 and the inclination angle of the second thin shallow groove 45 is obtained. Used as an element for

  Specifically, the second thin shallow groove 45 is connected orthogonally to the first thin shallow groove 40, and the range from the inner connection portion 45 a to the bent portion 46 is relative to the first thin shallow groove 40. The orthogonal portion 47 is formed at about 90 °. The second shallow groove 45 extends from the front side in the tire rotation direction to the rear side in the tire rotation direction as the range from the bent portion 46 to the outer connection portion 45b moves from the first thin shallow groove 40 side to the rib edge sipe 35 side. Inclined with respect to the tire width direction in the direction toward the side. In this way, the second shallow groove 45 having the bent portion 46 has an angle α with respect to the tire circumferential direction of the rear portion in the tire rotation direction in the straight line 48 connecting the inner connection portion 45a and the outer connection portion 45b. However, it has an acute angle. In addition, it is preferable that the length of the orthogonal part 47 of the 2nd thin shallow groove | channel 45 exists in the range of 1.0 mm or more and 3.0 mm or less.

  Further, the rib edge sipe 35 is inclined with respect to the tire width direction in the direction from the front side in the tire rotation direction to the rear side in the tire rotation direction as it goes from the end portion 35a side to the opening end portion 35b side. That is, in the rib edge sipe 35 as well as the second shallow groove 45, the angle β formed by the rear portion in the tire rotation direction with respect to the tire circumferential direction is an acute angle. The angle of the rib edge sipe 35 is also used as an element for obtaining the inclination angle of the rib edge sipe 35 by indicating the extending direction of the rib edge sipe 35 with the straight line connecting both ends of the rib edge sipe 35. In the present embodiment, the rib edge sipe 35 is formed in a straight line, and the rib edge sipe 35 itself is used as it is because the rib edge sipe 35 overlaps the straight line connecting both ends and the rib edge sipe 35. It is done.

  The angle α of the second narrow groove 45 with respect to the tire circumferential direction is preferably in the range of 60 ° to 80 °, and the angle β of the rib edge sipe 35 with respect to the tire circumferential direction is also 60 ° to 80 °. It is preferable to be within the following range. The difference between the angle α of the second narrow shallow groove 45 and the angle β of the rib edge sipe 35 is preferably within a range of ± 10 °.

  6 is a cross-sectional view taken along line FF in FIG. The rib edge sipe 35 is formed such that the wall portion 36 is inclined with respect to the tire radial direction, and the wall portion 36 is located on the front side in the tire rotation direction on the bottom 38 side rather than on the opening 37 side. In the tire circumferential direction with respect to the tire radial direction.

  In the above description, the second rib 22 is used to describe the circumferential sipe 30, the rib edge sipe 35, the first narrow groove 40, and the second narrow groove 45, but also in the center rib 21, the circumferential sipe 30, The rib edge sipe 35, the first narrow shallow groove 40, and the second thin shallow groove 45 are provided in the same form.

  The pneumatic tire 1 according to the present embodiment configured as described above is used for a heavy-duty pneumatic tire. When the pneumatic tire 1 is mounted on the vehicle, the pneumatic tire 1 is mounted on the vehicle in a rim-assembled and inflated state. The pneumatic tire 1 assembled with a rim on a rim wheel is used by being mounted on a large vehicle such as a truck or a bus, and is particularly mounted on a front wheel that is a steering wheel.

  When the vehicle equipped with the pneumatic tire 1 travels, the pneumatic tire 1 rotates while the tread surface 3 positioned below the tread surface 3 is in contact with the road surface. When driving on a dry road surface with a vehicle equipped with pneumatic tires 1, the driving force or braking force is transmitted to the road surface or the turning force is generated mainly by the frictional force between the tread surface 3 and the road surface. To drive. Further, when traveling on a wet road surface, water between the tread surface 3 and the road surface enters the circumferential main groove 10 and the like while discharging water between the tread surface 3 and the road surface through these grooves. Run. As a result, the tread surface 3 is easily grounded to the road surface, and the vehicle can travel by the frictional force between the tread surface 3 and the road surface.

  When the vehicle travels, a large load is applied to the ground contact area on the tread surface 3, but the distribution of the ground pressure on the tread surface 3 due to the load acting on the ground contact area changes in accordance with the traveling state of the vehicle. . That is, in the ground contact area of the tread surface 3, a portion where the ground pressure is high and a portion where the ground pressure is relatively small are generated. When the contact pressure of the tread surface 3 varies depending on the position, uneven wear tends to occur. However, in the pneumatic tire 1 according to the present embodiment, the circumferential sipe 30, the rib edge sipe 35, A first thin shallow groove 40 and a second thin shallow groove 45 are provided, and the rib 20 is divided into a plurality of block portions 25. Thereby, the difference of the compression amount of the rib 20 can be relieved, and the local increase in the contact pressure of the tread surface 3 can be suppressed.

  That is, when the tread surface 3 is grounded and a portion with a high ground pressure is generated, the circumferential sipe 30, the rib edge sipe 35, the first shallow groove 40, the second sipe 30 according to the direction in which the ground pressure acts. When the shallow groove 45 is crushed, the block portion 25 of the rib 20 can be deformed in the tire circumferential direction or the tire width direction. Thereby, since the amount of compression of the rib 20 is suppressed from being locally increased and the contact pressure is dispersed, uneven wear due to a local increase in the contact pressure during the contact of the tread surface 3 is suppressed. be able to.

  In addition, a first shallow groove 40 is formed between adjacent circumferential sipe 30 in the tire circumferential direction, and a second shallow groove 45 is formed between the first shallow groove 40 and the rib edge sipe 35. Since it is formed, it is possible to improve uneven wear resistance at the initial stage of use of the pneumatic tire 1 from when it is new, that is, at the beginning of running. That is, when the pneumatic tire 1 is new, the tread surface 3 is not worn down, so that the circumferential main groove 10 has a deeper groove depth than the state in which the tread surface 3 is worn. Since one side of the block portion 25 of the rib 20 is partitioned by the circumferential main groove 10, when the rib 20 is divided into the plurality of block portions 25 only by the circumferential sipe 30 and the rib edge sipe 35, the circumferential main groove When the groove depth of 10 is deep, the rigidity of each block portion 25 when the pneumatic tire 1 is new may be too low. In this case, when the tread surface 3 is grounded, the block portion 25 is excessively tilted by the ground pressure, and therefore, partial wear due to the excessive collapse of the block portion 25 may occur.

  On the other hand, the first narrow groove 40 is formed between the circumferential sipes 30 adjacent to each other in the tire circumferential direction, and the second shallow groove 45 is connected to the first shallow groove 40 to By partitioning the corner portion 26 with the first thin shallow groove 40 and the second thin shallow groove 45, the block portion 25 can be prevented from falling too much. That is, the first shallow groove 40 and the second thin groove 45 have a groove depth shallower than the circumferential sipe 30 and the rib edge sipe 35, so that the corner portion 26 of the block portion 25 is formed in the first shallow groove. By partitioning with the groove 40 and the second thin shallow groove 45, large deformation in the vicinity of the corner portion 26 of the block portion 25 can be suppressed. Thereby, when the tread surface 3 is grounded, it is possible to suppress the block portion 25 from falling too much due to the contact pressure, and it is possible to suppress uneven wear caused by the block portion 25 being excessively fallen in the initial stage of traveling. Accordingly, it is possible to suppress the situation where the pneumatic tire 1 is removed from the vehicle at an early stage due to uneven wear at the initial stage of travel, and it is possible to suppress the travel distance in which the pneumatic tire 1 can be continuously used from being shortened. Moreover, since uneven wear at the initial stage of travel can be suppressed, it is possible to suppress subsequent wear at the end of the run resulting from uneven wear at the initial stage of travel. As a result, uneven wear resistance can be improved and the wear life, which is the life due to wear, can be extended.

The first Hosoasamizo 40, since the maximum groove depth _{D N1} is in the range of 0.5mm ≦ _{D N1} ≦ 4.0mm, collapsing more reliably block portion 25 by the first Hosoasamizo 40 In addition to the suppression, the effect of dispersing the ground pressure by the first thin shallow groove 40 can be maintained for a predetermined period. In other words, the maximum groove depth _{D N1} of the first Hosoasamizo _40, if a D N1 <0.5 mm, since the maximum groove depth _{D N1} of the first Hosoasamizo 40 is too shallow, the tread surface 3 There is a possibility that the first narrow groove 40 may disappear early due to wear. In this case, since the effect of dispersing the contact pressure by the first thin shallow grooves 40 disappears at an early stage in the early stage of travel, it may be difficult to effectively suppress uneven wear in the early stage of travel. . The maximum groove depth _{D N1} of the first Hosoasamizo _40, if a D N1> 4.0 mm, since the maximum groove depth _{D N1} of the first Hosoasamizo 40 is too deep, the block portion 25 It may be difficult to effectively suppress the collapse, and it may be difficult to suppress the partial wear caused by the block portion 25 being excessively collapsed.

In contrast, the maximum groove depth _{D N1} of the first Hosoasamizo 40, if in the range of 0.5mm ≦ _{D N1} ≦ 4.0mm, collapsing of the block portion 25 by the first Hosoasamizo 40 In addition to being effectively suppressed, the effect of dispersing the contact pressure by the first thin shallow grooves 40 can be maintained for a predetermined travel distance after the pneumatic tire 1 is used from a new article. For example, when the pneumatic tire 1 starts to be used from a new article and the wear of the tread surface 3 progresses, the groove depth of the circumferential main groove 10 becomes shallower, and the size of the collapse of the block part 25 is less than the block part 25. The effect of dispersing the ground pressure by the first shallow groove 40 can be maintained until the wear becomes small enough to prevent the occurrence of uneven wear due to the collapse of the first and second shallow grooves. As a result, uneven wear resistance can be improved more reliably.

The second Hosoasamizo 45, since the maximum groove depth _{D N2} is in the range of 0.5mm ≦ _{D N2} ≦ 4.0mm, collapsing more reliably block portion 25 by the second Hosoasamizo 45 In addition to being suppressed, the effect of dispersing the ground pressure by the second thin shallow groove 45 can be maintained for a predetermined period. In other words, the maximum groove depth _{D N2} of the second Hosoasamizo _45, if a D N2 <0.5 mm, since the maximum groove depth _{D N2} of the second Hosoasamizo 45 is too shallow, the tread surface 3 There is a possibility that the second narrow groove 45 may disappear at an early stage due to wear. In this case, since the effect of dispersing the contact pressure by the second narrow groove 45 disappears at an early stage in the early stage of traveling, it may be difficult to effectively suppress uneven wear in the early stage of traveling. . The maximum groove depth _{D N2} of the second Hosoasamizo _45, if a D N2> 4.0 mm, since the maximum groove depth _{D N2} of the second Hosoasamizo 45 is too deep, the block portion 25 It may be difficult to effectively suppress the collapse, and it may be difficult to suppress the partial wear caused by the block portion 25 being excessively collapsed.

In contrast, the maximum groove depth _{D N2} of the second Hosoasamizo 45, if in the range of 0.5mm ≦ _{D N2} ≦ 4.0mm, collapsing of the block portion 25 by the second Hosoasamizo 45 It is possible to effectively suppress and maintain the effect of dispersing the contact pressure by the second narrow shallow groove 45 for a predetermined travel distance after starting to use the pneumatic tire 1 from a new one. For example, when the pneumatic tire 1 starts to be used from a new article and the wear of the tread surface 3 progresses, the groove depth of the circumferential main groove 10 becomes shallower, and the size of the collapse of the block part 25 is less than the block part 25. The effect of dispersing the ground pressure by the second thin shallow groove 45 can be maintained until the wear becomes small enough to prevent the occurrence of uneven wear due to the collapse of the second. As a result, uneven wear resistance can be improved more reliably.

Moreover, the circumferential sipe 30, the maximum and the depth _{D SC} of the circumferential sipe 30, the relationship between the maximum groove depth D of the circumferential main groove 10, 0.50 ≦ _(D SC /D)≦0.80 Therefore, until the end of wear of the tread surface 3, the block portion 25 can be appropriately deformed to disperse the contact pressure, and uneven wear can be suppressed. That is, the relationship between the maximum groove depth D of the maximum depth _{D SC} and the circumferential direction main grooves 10 in the circumferential sipe _30, when a (D SC /D)<0.50 the maximum of the circumferential sipe 30 since the depth D _SC is too shallow, can not be circumferential sipe 30 to wear the end of the tread surface 3 is present, the circumferential sipe 30 in the middle progression of wear is likely to disappear. In this case, since the effect of dispersing the contact pressure by the circumferential sipe 30 does not last until the end of wear, it may be difficult to effectively suppress uneven wear of the tread surface 3 until the end of wear. The relationship between the maximum groove depth D of the maximum depth _{D SC} and the circumferential direction main grooves 10 in the circumferential sipe _30, when a (D SC /D)>0.80 the maximum of the circumferential sipe 30 Since the depth _DSC is too deep, there is a possibility that the deformation amount of the block portion 25 when the tread surface 3 is grounded becomes too large. In this case, the block portion 25 is deformed so that the block portion 25 falls too much, and it may be difficult to suppress uneven wear.

In contrast, the relationship between the maximum groove depth D of the maximum depth _{D SC} and the circumferential direction main grooves 10 in the circumferential sipe 30, is within the range of 0.50 ≦ _(D SC /D)≦0.80 In this case, the block portion 25 can be deformed until the end of wear by the circumferential sipe 30 so that the collapse of the block portion 25 does not become too large. Thereby, the contact pressure of the tread surface 3 can be dispersed even after the initial wear of the tread surface 3, and uneven wear can be suppressed until the end of wear. As a result, uneven wear resistance can be improved more reliably.

Further, the rib edge sipes 35, rib and maximum depth _{D SE} edge sipe 35, the relationship between the maximum groove depth D of the circumferential main groove 10, 0.60 ≦ _(D SE /D)≦0.90 Therefore, until the end of wear of the tread surface 3, the block portion 25 can be appropriately deformed to disperse the contact pressure, and uneven wear can be suppressed. That is, if the relationship between the maximum groove depth D of the maximum depth _{D SE} and the circumferential direction main groove 10 of the rib edge sipes 35 _is a (D SE /D)<0.60 the largest rib edge sipes 35 Since the depth _DSE is too shallow, the rib edge sipe 35 cannot exist until the end of wear of the tread surface 3, and the rib edge sipe 35 may disappear during the progress of wear. In this case, since the effect of dispersing the contact pressure by the rib edge sipes 35 does not last until the end of wear, it may be difficult to effectively suppress uneven wear of the tread surface 3 until the end of wear. Also, if the relationship between the maximum groove depth D of the maximum depth _{D SE} and the circumferential direction main groove 10 of the rib edge sipes 35 _is a (D SE /D)>0.90 the largest rib edge sipes 35 Since the depth _DSE is too deep, there is a possibility that the deformation amount of the block portion 25 when the tread surface 3 is grounded becomes too large. In this case, the block portion 25 is deformed so that the block portion 25 falls too much, and it may be difficult to suppress uneven wear.

In contrast, the relationship between the maximum groove depth D of the maximum depth _{D SE} and the circumferential direction main groove 10 of the rib edge sipes 35, is within the range of 0.60 ≦ _(D SE /D)≦0.90 In this case, the block portion 25 can be deformed until the end of wear by the rib edge sipe 35 so that the collapse of the block portion 25 does not become too large. Thereby, the contact pressure of the tread surface 3 can be dispersed even after the initial wear of the tread surface 3, and uneven wear can be suppressed until the end of wear. As a result, uneven wear resistance can be improved more reliably.

  Further, the second shallow groove 45 is inclined with respect to the tire width direction in the direction from the front side in the tire rotation direction toward the rear side in the tire rotation direction from the inner connection portion 45a side to the outer connection portion 45b side. Therefore, the corner portion 26 on the kick-out side first shallow groove 40 side in the block portion 25 can be made an obtuse angle. That is, since the angle α formed by the rear portion in the tire rotation direction with respect to the tire circumferential direction is an acute angle, the second shallow groove 45 has a front side in the tire rotation direction. The angle formed by the portion with respect to the tire circumferential direction can be an obtuse angle, that is, the kick-out corner 26 of the block 25 can be an obtuse angle. As a result, the side on the kicking side of the block portion 25 gradually moves away from the road surface from the corner portion 26 toward the circumferential main groove 10 side, so that the vicinity of the corner portion 26 in each block portion 25 is grounded to the road surface to the end. Therefore, it is possible to suppress the ground pressure from becoming locally high. Therefore, it is possible to suppress that the contact pressure near the corner portion 26 on the kick-out side of the block portion 25 becomes too high at the beginning of traveling, and uneven wear is likely to occur. It can improve more reliably. As a result, the uneven wear resistance can be improved more reliably and the wear life can be extended.

  Further, the rib edge sipe 35 is inclined with respect to the tire width direction in the direction from the front side in the tire rotation direction to the rear side in the tire rotation direction as it goes from the terminal end portion 35a side to the opening end portion 35b side. The contact pressure in the vicinity of the rib edge 20a of the rib 20 can be effectively dispersed. That is, of the two block parts 25 arranged in the tire rotation direction, when the vicinity of the rib edge sipe 35 that defines the rear side in the tire rotation direction of the block part 25 on the front side in the tire rotation direction is grounded, the front side in the tire rotation direction The block portion 25 is deformed and supported by the block portion 25 on the rear side in the tire rotation direction, so that the contact pressure is dispersed. At that time, since the contact pressure tends to be high in the vicinity of the rib edge 20a, the rib edge sipe 35 is formed in a direction in which the angle β formed by the rear side portion in the tire rotation direction of the rib edge sipe 35 with respect to the tire circumferential direction becomes an acute angle. By inclining, the contact pressure in the vicinity of the rib edge 20a where contact pressure tends to be high can be more reliably distributed between the block portions 25 adjacent in the tire rotation direction. As a result, uneven wear caused by locally increasing ground pressure can be more reliably suppressed, and uneven wear resistance can be more reliably improved.

Moreover, the circumferential sipe 30 and the first Hosoasamizo 40, the length L _SC in the tire circumferential direction of the circumferential sipe 30, the relationship between the length L _N1 in the tire circumferential direction of the first Hosoasamizo 40 , 0.4 ≦ (L _N1 / L _SC ) ≦ 0.8, so that the ground pressure of the tread surface 3 can be more reliably dispersed while preventing the block portion 25 from falling too much in the initial stage of traveling. Can do. In other words, the length _{L SC} of the circumferential sipe 30, when the relationship between the length _{L N1} in the tire circumferential direction of the first Hosoasamizo 40 _is a _{<0.4 (L N1 / L SC} ) is circumferential Since the 1st thin groove 40 is too short with respect to the direction sipe 30, it may become difficult to suppress effectively that the block part 25 falls down too much by the contact pressure in the driving | running | working initial stage of the pneumatic tire 1. There is. In this case, there is a possibility that it is difficult to effectively suppress the partial wear caused by the collapse of the block portion 25 at the initial stage of traveling. Further, the length _{L SC} in the tire circumferential direction of the circumferential sipe 30, the relationship between the length _{L N1} in the tire circumferential direction of the first Hosoasamizo 40 _is the _{(L N1 / L SC)>} 0.8 In this case, since the first narrow groove 40 is too long with respect to the circumferential sipe 30, that is, the circumferential sipe 30 is too short, the block portion 25 may not be easily deformed. In this case, even when a portion where the ground pressure is locally increased when the tread surface 3 is grounded, it is difficult to effectively distribute the ground pressure and it may be difficult to suppress uneven wear. is there.

In contrast, the length _{L SC} of the circumferential sipe 30, the relationship between the length _{L N1} in the tire circumferential direction of the first Hosoasamizo _{40, 0.4 ≦ (L N1 /} L SC) ≦ 0.8 If it is within the range, the contact pressure of the tread surface 3 can be dispersed more reliably while preventing the block portion 25 from falling too much in the initial stage of travel. As a result, uneven wear resistance can be improved more reliably.

  Further, since the rib edge sipe 35 is inclined with respect to the tire radial direction in the direction of the front side in the tire rotation direction on the bottom 38 side rather than the opening 37 side, the tire rotation of the rib edge sipe 35 is increased. When the block portion 25 located on the front side in the direction is deformed, the block portion 25 can be more reliably supported by the block portion 25 located on the rear side in the tire rotation direction of the rib edge sipe 35. That is, when the block portion 25 is deformed, the block portion 25 is deformed from the tread surface 3 side. The direction of the force acting on the block portion 25 located on the side is an angle close to the angle perpendicular to the wall portion 36 of the rib edge sipe 35 that is inclined with respect to the tire radial direction. For this reason, the block portion 25 located on the rear side in the tire rotation direction can more efficiently support the block portion 25 located on the front side in the tire rotation direction, and the contact pressure when the tread surface 3 is in contact with the ground is reduced. The block portions 25 adjacent to each other can be more reliably dispersed. As a result, uneven wear resistance can be improved more reliably.

  In addition, the two second shallow grooves 45 connected to one first shallow groove 40 are offset from each other in the tire circumferential direction, and are connected to the first shallow groove 40 at different positions in the tire circumferential direction. Therefore, the ground pressure can be more reliably dispersed. That is, the contact pressure when the tread surface 3 is grounded is likely to be concentrated at the position where the edges of the grooves and sipes intersect, but the two second shallow grooves 45 are connected to the first shallow grooves 40. By offsetting the position relatively in the tire circumferential direction, the respective corner portions 26 of the two block portions 25 located on both sides of the first narrow groove 40 in the tire width direction can be offset in the tire circumferential direction. it can. Thereby, since the corner | angular part 26 of the block part 25 which is a site | part which a ground pressure tends to concentrate can suppress concentrating on a narrow range and the corner | angular part 26 can be disperse | distributed, a ground pressure can be more reliably disperse | distributed. be able to. As a result, uneven wear resistance can be improved more reliably.

  Further, since a plurality of rib edge sipes 35 are formed in the tire circumferential direction in the vicinity of the rib edge 20a of the rib 20, the ground pressure at a position where the ground pressure tends to increase can be more reliably dispersed. That is, since the ground contact surface does not exist at the position where the circumferential main groove 10 is formed, the contact pressure tends to increase in the vicinity of the rib edge 20a of the rib 20 located on both sides of the circumferential main groove 10 accordingly. ing. A plurality of rib edge sipes 35 are disposed in the vicinity of the rib edge 20a where the ground pressure tends to increase. Therefore, when the ground pressure near the rib edge 20a is locally increased, the rib edge sipes of the portion where the ground pressure is high. When 35 is crushed and the rib 20 is deformed in the tire circumferential direction, it is possible to suppress the amount of compression of the rib 20 from being locally increased. Thereby, since the contact pressure can be dispersed, uneven wear due to the locally increased contact pressure can be suppressed. As a result, uneven wear resistance can be improved more reliably.

  Further, since the circumferential sipe 30 extends in the tire circumferential direction while being bent, the entire length of the circumferential sipe 30 can be increased as compared with the case where the circumferential sipe 30 extends linearly. Thereby, the compression amount of the block part 25 at the time of grounding of the tread surface 3 can be relieved more reliably, and grounding pressure can be more reliably disperse | distributed. As a result, uneven wear resistance can be improved more reliably.

  Further, the second narrow groove 45 has an orthogonal part 47 formed at about 90 ° with respect to the first shallow groove 40, and the orthogonal part 47 is connected to the first thin groove 40. Even when the second thin shallow groove 45 and the first thin shallow groove 40 are connected at an angle other than 90 ° relatively, the second thin shallow groove 45 is connected to the first thin shallow groove 40 in a substantially perpendicular form. Can be connected to. Thereby, it can suppress that the corner | angular part 26 of the block part 25 forms with an acute angle. That is, when the corner portion 26 of the block portion 25 is formed with an acute angle, the corner portion 26 may be chipped. However, the second shallow groove 45 is formed with respect to the first thin groove 40. By connecting in a substantially orthogonal form, it is possible to suppress the corner portion 26 of the block portion 25 from being formed with an acute angle, and to prevent the corner portion 26 from being chipped. As a result, it is possible to improve uneven wear resistance and to suppress chipping of the block portion 25 formed by the rib 20.

  The circumferential sipe 30, the rib edge sipe 35, the first narrow groove 40, and the second narrow groove 45 may be formed in a shape other than the shape in the pneumatic tire 1 according to the above-described embodiment. FIG. 7 is a modified example of the pneumatic tire 1 according to the embodiment, and is an explanatory view showing a state in which the circumferential sipe 30 is formed in a straight line shape. In the embodiment described above, the circumferential sipe 30 is formed to bend in the tire width direction while extending in the tire circumferential direction, but the circumferential sipe 30 is, for example, in the tire circumferential direction as shown in FIG. It may be formed in a linear shape along.

  FIG. 8 is a modified example of the pneumatic tire 1 according to the embodiment, and is an explanatory view showing a state in which the rib edge sipes 35 and the second shallow grooves 45 are formed along the tire width direction. In the above-described embodiment, the rib edge sipe 35 and the second shallow groove 45 are formed to be inclined in the tire circumferential direction while extending in the tire width direction. As shown in FIG. 8, 45 may be formed in a linear shape along the tire width direction.

  FIG. 9 is a modified example of the pneumatic tire 1 according to the embodiment, and shows a state where the positions of the two second shallow grooves 45 connected to the first shallow grooves 40 in the tire circumferential direction are the same position. It is explanatory drawing shown. In the above-described embodiment, the two second shallow grooves 45 connected to the same first shallow groove 40 are connected to the first shallow grooves 40 at positions different in the tire circumferential direction. However, as shown in FIG. 9, the two second shallow grooves 45 may be connected to the first shallow grooves 40 at the same position in the tire circumferential direction.

Further, in the above embodiment, the groove width _{W N1} of the first Hosoasamizo 40 and groove width _{W N2,} and the maximum groove depth _{D N1} of the first Hosoasamizo 40 of the second Hosoasamizo 45 second fine maximum groove depth D _N2 shallow grooves 45, although almost the same size, respectively, which may be different from each other. For example, than the maximum groove depth _{D N2} of the second Hosoasamizo 45 may be deeper maximum groove depth _{D N1} of the first Hosoasamizo 40. That is, since the second shallow groove 45 extends in a direction close to the tire width direction, the direction of the groove width is close to the tire circumferential direction. For this reason, when the groove depth of the second thin shallow groove 45 is deeper than the groove depth of the first thin shallow groove 40, the block portions 25 located on both sides in the groove width direction of the second thin shallow groove 45 are: When the pneumatic tire 1 rotates, the pneumatic tire 1 easily moves in the direction in which the groove width of the second shallow groove 45 changes, that is, the block portion 25 easily falls down in the tire circumferential direction. In this case, so-called heel and toe wear that is uneven wear in which the rear end portion of the block portion 25 in the tire rotation direction wears more than the front end portion in the tire rotation direction is likely to occur. On the other hand, when the groove depth of the first thin shallow groove 40 is deeper than the groove depth of the second thin shallow groove 45, such uneven wear is less likely to occur. If when varying the groove depth and the second Hosoasamizo 45, than the maximum groove depth D _N2 of the second Hosoasamizo 45 towards the maximum groove depth D _N1 of the first Hosoasamizo 40 deep It is preferable to do so.

  As described above, the circumferential sipe 30 and the first shallow groove 40 formed substantially in the tire circumferential direction, and the rib edge sipe 35 and the second shallow groove 45 formed substantially in the tire width direction. If the rib 20 is divided into a plurality of block portions 25 and the corner portion 26 of the block portion 25 can be partitioned by the first shallow groove 40 and the second thin groove 45, the circumferential sipe 30 and the rib edge The fine shapes of the sipe 35, the first thin shallow groove 40, and the second thin shallow groove 45 are not limited.

  In the above-described embodiment, a plurality of rib edge sipes 35 that are not connected to the second thin shallow grooves 45 are provided between the rib edge sipes 35 that are connected to the second thin shallow grooves 45. The rib edge sipes 35 other than the rib edge sipes 35 connected to the narrow shallow grooves 45 may not be provided. If the rib edge sipe 35 is provided with at least the rib edge sipe 35 that can partition the block portion 25 by being connected to the second narrow groove 45, the presence or absence of the other rib edge sipe 35 may be determined. Absent.

  In the above-described embodiment, the center rib 21 and the second rib 22 are all formed in the same form in the circumferential sipe 30, the rib edge sipe 35, the first narrow groove 40, and the second thin groove 45. However, they may be formed in different forms depending on the ribs 20. Moreover, although the pneumatic tire 1 which concerns on embodiment mentioned above is the pneumatic tire 1 with which the tire rotation direction was designated, the circumferential direction sipe 30, the rib edge sipe 35, the 1st shallow groove 40, 2nd The pneumatic tire 1 in which the rib 20 is divided into the plurality of block portions 25 by the thin shallow grooves 45 may be one in which the tire rotation direction is not specified.

  In the embodiment described above, four circumferential main grooves 10 are formed, but the number of circumferential main grooves 10 may be other than four. That is, five ribs 20 defined by the circumferential main groove 10 are formed, but the number of ribs 20 may be other than five. Regardless of the number of the circumferential main grooves 10 and the ribs 20, the ribs 20 are divided into a plurality of block portions 25 by the circumferential sipe 30, the rib edge sipe 35, the first narrow groove 40, and the second narrow groove 45. At the same time, the corner portion 26 of the block portion 25 is partitioned by the first narrow shallow groove 40 and the second thin shallow groove 45, whereby uneven wear resistance can be improved.

〔Example〕
10A to 10C are tables showing the results of performance tests of the pneumatic tire 1. Hereinafter, with respect to the pneumatic tire 1 described above, the performance of the conventional pneumatic tire, the pneumatic tire 1 according to the present invention, and the pneumatic tire of the comparative example compared with the pneumatic tire 1 according to the present invention. The evaluation test will be described. In the performance evaluation test, a test for uneven wear performance, which is performance for uneven wear of the tread surface 3, was performed.

  In these performance evaluation tests, a pneumatic tire 1 having a tire size specified by JATMA of 295 / 75R22.5 size is assembled on a rim wheel of a specified rim specified by JATMA, and the air pressure is specified by JATMA. The test was carried out by adjusting the maximum air pressure and mounting the test vehicle on a 2-DD test vehicle (tractor head). The evaluation method of uneven wear performance was that the degree of occurrence of uneven wear on the tread surface 3 was measured after running 50,000 km on a test vehicle, and the degree of occurrence of uneven wear was displayed as an index with the conventional example described later as 100. . The larger this value is, the smaller the degree of occurrence of uneven wear is, indicating that the uneven wear resistance is excellent.

  An evaluation test is a pneumatic tire compared with the conventional example which is an example of the conventional pneumatic tire 1, Examples 1-19 which are the pneumatic tire 1 which concerns on this invention, and the pneumatic tire 1 which concerns on this invention. It carried out about 21 types of pneumatic tires of a certain comparative example. Among these pneumatic tires 1, the conventional pneumatic tire has the circumferential sipe 30 and the rib edge sipe 35, but the first narrow groove 40 and the second narrow groove 45 are present. Not done. Further, the pneumatic tire of the comparative example has the circumferential sipe 30, the rib edge sipe 35, and the first narrow groove 40, but does not have the second shallow groove 45.

On the other hand, Examples 1 to 19, which are examples of the pneumatic tire 1 according to the present invention, all have a circumferential sipe 30, a rib edge sipe 35, a first narrow groove 40, and a second shallow groove 45. ing. Further, the pneumatic tire 1 according to Examples 1 to 19, the maximum groove depth _{D N1} of the first Hosoasamizo 40, the maximum of the maximum groove depth _{D N2,} the circumferential main groove 10 of the second Hosoasamizo 45 maximum depth D _SC of the circumferential sipe 30 with respect to the groove depth _D, the maximum depth D _SE rib edge sipes 35 with respect to the maximum groove depth D of the circumferential main groove _10, the angle α of the second Hosoasamizo 45 acute Whether or not the angle β of the rib edge sipe 35 is an acute angle, and the length L _N1 of the first shallow groove 40 in the tire circumferential direction with respect to the length L _SC of the circumferential sipe 30 in the tire circumferential direction. But they are different.

  As a result of performing an evaluation test using these pneumatic tires 1, as shown in FIGS. 10A to 10C, the pneumatic tires 1 of Examples 1 to 19 are more resistant to uneven wear than conventional examples and comparative examples. It was found that the performance was improved. That is, the pneumatic tire 1 according to Examples 1 to 19 can improve the uneven wear resistance and extend the wear life.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Tread surface 10 Circumferential direction main groove 11 Center circumferential direction main groove 12 Shoulder circumferential direction main groove 15 Circumferential direction narrow groove 20 Rib 20a Rib edge 21 Center rib 22 Second rib 23 Shoulder rib 25 Block part 26 Corner Part 30 Circumferential sipe 30a End part 35 Rib edge sipe 35a Termination part 35b Open end part 36 Wall part 37 Open part 38 Bottom part 40 First narrow groove 40a End part 45 Second thin groove 45a Inner connection part 45b Outer connection part 46 Bending part 47 Orthogonal part 48 Straight line

Claims (8)

A plurality of circumferential main grooves extending in the tire circumferential direction;
At least one end side in the tire width direction is a rib defined by the circumferential main groove;
A circumferential sipe that extends in the tire circumferential direction and is formed in the ribs apart from each other in the tire circumferential direction;
A plurality of ribs are formed on the rib side by side in the tire circumferential direction, one end terminates in the rib, and the other end opens to the circumferential main groove,
A plurality of first shallow shallowers extending in the tire circumferential direction and having a groove depth shallower than the circumferential sipe and the rib edge sipe and having both ends connected to the circumferential sipe adjacent in the tire circumferential direction. Groove,
A plurality of second shallow shallow grooves formed at a groove depth shallower than the circumferential sipe and the rib edge sipe and having one end connected to the first shallow groove and the other end connected to the rib edge sipe. Groove,
A pneumatic tire characterized by comprising: 2. The pneumatic tire according to claim 1, wherein the first narrow shallow groove has a maximum groove depth D _{N1 in} a range of 0.5 mm ≦ D _N1 ≦ 4.0 mm. 3. The pneumatic tire according to claim 1, wherein the second narrow shallow groove has a maximum groove depth DN ₂ within a range of 0.5 mm ≦ D _N2 ≦ 4.0 mm. The circumferential sipe, and the maximum depth _{D SC} of the circumferential sipe, the relationship between the maximum groove depth D of the circumferential main grooves, a range of 0.50 ≦ _(D SC /D)≦0.80 The pneumatic tire according to any one of claims 1 to 3. The rib edge sipe, and the maximum depth _{D SE} of the rib edge sipes, the relationship between the maximum groove depth D of the circumferential main grooves, a range of 0.60 ≦ _(D SE /D)≦0.90 It is inside. The pneumatic tire of any one of Claims 1-4.   The second shallow groove extends from the front side in the tire rotation direction to the rear side in the tire rotation direction from the end side connected to the first shallow groove toward the end side connected to the rib edge sipe. The pneumatic tire according to any one of claims 1 to 5, wherein the pneumatic tire is inclined in a direction toward the tire width direction.   The rib edge sipes are tires in a direction from the front side in the tire rotation direction to the rear side in the tire rotation direction from the end side on the side terminating in the rib toward the end side opening in the circumferential main groove. The pneumatic tire according to any one of claims 1 to 6, which is inclined with respect to the width direction. Wherein the circumferential sipes and the first narrow shallow groove, the length L _SC in the tire circumferential direction of the circumferential sipe, the relationship between the length L _N1 in the tire circumferential direction of the first narrow shallow groove, 0 The pneumatic tire according to any one of claims 1 to 7, which is within a range of .4 ≦ (L _N1 / L _SC ) ≦ 0.8.

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