JP6597013B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that can improve wear resistance and wet performance and improve the appearance of the tire in the late stage of wear.

  Pneumatic tires mounted on commercial vehicles, especially taxis, have a longer mileage than ordinary pneumatic tires for passenger cars, and also have excellent wear resistance due to repeated braking and driving at medium and low speeds. On the other hand, since it travels frequently even in rainy weather, excellent wet performance is required (see, for example, cited document 1). Measures to improve wet performance include, for example, increasing the groove area. However, if the groove area increases, it becomes difficult to secure a sufficient ground contact area, so wear resistance performance is maintained. There is a problem that it becomes difficult. Thus, since the wear resistance performance and the wet performance are contradictory performances, a countermeasure for making these highly compatible is demanded.

  In addition, in the pneumatic tires mounted on taxis and the like, from the viewpoint of impression given to passengers, the tire appearance is required to be good even in the late stage of wear, and the above-mentioned wear resistance performance and wet performance are required. In addition to compatibility, further improvements are required.

Japanese Patent Laid-Open No. 06-191229

  An object of the present invention is to provide a pneumatic tire capable of improving the wear resistance and wet performance and improving the appearance of the tire in the late stage of wear.

In order to achieve the above object, a pneumatic tire according to the present invention is a pneumatic tire in which at least three main grooves extending in the tire circumferential direction are provided on a tread surface, and a plurality of rows of land portions are defined by the main grooves. A plurality of indentations in the tire circumferential direction on the side surface on the outermost main groove side of the shoulder land portion of the outermost main groove located on the outermost side in the tire width direction of the main groove. spaced, and, the plurality of holes in the tread surface of the shoulder land portions are provided at intervals in the tire circumferential direction, and the recess and the hole is shifted in the tire circumferential direction and the tire width direction disposed A plurality of communicating sipes extending in the tire width direction are formed in the shoulder land portion, one end portion of each communicating sipes communicates with the hole, and the other end portion of each communicating sipes is the shoulder land Department of parts Characterized in that it opens in Ya width direction outer side.

  In the present invention, by providing a portion where the groove area of the main groove is large by the recessed portion provided on the side surface of the shoulder land portion, the ground contact area as in the case of expanding the groove area of the main groove over the entire circumference. It is possible to increase the drainage performance by sufficiently securing the groove area while avoiding the significant decrease in wear resistance and the wear resistance. On the other hand, the wear life of the shoulder land portion can be extended by reducing the rigidity difference in the tire circumferential direction of the shoulder land portion by the hole provided in the tread of the shoulder land portion. Moreover, since this hole can take in the water between the tread of a shoulder land part, and a road surface, it is advantageous in improving wet performance. Furthermore, since the hole maintains a shape close to that of a new article even after wear compared to a groove (particularly, a lug groove whose groove depth gradually decreases toward a general end portion), The tire appearance can be kept good.

  In the present invention, the hole is disposed on the inner side in the tire width direction than the tire ground contact end and on the outer side in the tire width direction with respect to the recessed portion, while the plurality of lug grooves extending in the tire width direction on the shoulder land portion in the tire circumferential direction. It is preferable that the lug groove is formed at intervals, and the lug groove is terminated without being communicated with the outermost main groove at a position on the inner side in the tire width direction from the tire contact end and on the outer side in the tire width direction from the hole. By providing the lug groove in the shoulder land portion in this way and defining the positional relationship between the hole and the ground contact end, the outermost main groove, and the lug groove, it is possible to effectively equalize the rigidity of the shoulder land portion. This is advantageous for improving wear resistance.

  Alternatively, while the holes are disposed in the tire width direction inner side than the tire ground contact end and in the tire width direction outer side than the recessed part, a plurality of sipes extending in the tire width direction are spaced apart in the tire circumferential direction on the shoulder land portion. It is preferable that the sipe is terminated without being communicated with the outermost main groove at a position on the inner side in the tire width direction from the tire contact end and on the outer side in the tire width direction from the hole. By providing a sipe in the shoulder land portion in this way and defining the positional relationship between the hole and the ground contact end, the outermost main groove, and the sipe, the rigidity of the shoulder land portion can be effectively equalized, This is advantageous for improving the wear resistance.

  In this invention, it is preferable that the hollow amount with respect to the side surface of the shoulder land part of a hollow part is 20 to 80% of the groove width GW of the outermost main groove. By defining the dimensions of the recesses in this way, wet performance can be improved while maintaining wear resistance.

  In this invention, it is preferable that the area in the tread of the shoulder land part of a hole is 30 to 300% of the area in the tread of the shoulder land part of a hollow part. By defining the areas of the holes and the recesses in this way, it is advantageous to achieve both wear resistance and wet performance.

  In the present invention, while the side surface of the shoulder land portion is parallel to the tire circumferential direction, the recess portion connects the recess surface parallel to the side surface of the shoulder land portion and the recess surface and the side surface of the shoulder land portion. It is preferable that it is comprised with the connection surface. By forming the hollow portion in such a shape, it is possible to effectively reduce the wear energy with respect to the shoulder land portion during traveling, which is advantageous for improving the wear resistance.

In the present invention, a plurality of communicating sipes extending in the tire width direction are formed in the shoulder land portion, one end portion of each communicating sipes communicates with the hole, and the other end portion of each communicating sipes is the shoulder land portion. you opening of the tire width direction outside. By providing a communication sipe in this way, it is possible to drain water taken in the hole efficiently without reducing the rigidity of the shoulder land, and to achieve both wear resistance and wet performance. Become advantageous.

In the present invention, it is preferable that the communication sipe communicates with a position within 25% of the circumferential length of the hole from the center of the hole. By defining the arrangement of the communicating sipes in this way, the rigidity of the shoulder land portion can be more effectively made uniform in the tire circumferential direction, which is advantageous for improving the wear resistance.

  In the present invention, the distance from the center in the tire circumferential direction of the hole to the center line of the lug groove is preferably 20% to 80% of the distance between the centers of the recesses adjacent in the tire circumferential direction. By arranging the hole, the recessed portion, and the lug groove in this manner, the rigidity of the shoulder land portion can be more effectively made uniform in the tire circumferential direction, which is advantageous in improving the wear resistance performance. .

  In the present invention, the distance from the center of the hole in the tire width direction to the tire ground contact edge is preferably 20% to 80% of the distance from the side surface of the shoulder land portion to the tire ground contact edge. By arranging the hole in this direction, the rigidity of the shoulder land portion can be more effectively made uniform in the tire circumferential direction, which is advantageous for improving the wear resistance.

  In this invention, it is preferable that the tire circumferential direction length of a hollow part is 20%-180% of the length between the hollow parts adjacent to a tire circumferential direction. By defining the dimensions of the recesses in this way, the rigidity of the shoulder land portions can be more effectively made uniform in the tire circumferential direction, which is advantageous for improving the wear resistance performance.

  In the present invention, the length of the hole in the tire circumferential direction is preferably 1 to 5 times the length of the hole in the tire width direction. By defining the hole dimensions in this way, the rigidity of the shoulder land portion can be more effectively uniformed in the tire circumferential direction, which is advantageous for improving the wear resistance.

  In the present invention, the ratio of the groove area of the main groove to the total groove area included in the grounding region is 60% to 70%, while the groove area ratio of the entire grounding region is 10% to 20%, and It is preferable that the groove area ratio of the shoulder land portion is smaller than the groove area ratio of the center land portion. Setting the groove area ratio in this way is advantageous for improving the wear resistance.

  In the present invention, in the tire meridian cross section, while the center land portion bulges with respect to the center profile line consisting of the center reference arc passing through each edge point on the tread of the center land portion located inside the outermost main groove, The shoulder land portion bulges against the shoulder profile line consisting of the shoulder reference arc that contacts the center reference arc through the edge point on the tread of the shoulder land portion, and the bulge amount and shoulder of the center land portion with respect to the center profile line It is preferable that the bulge amount with respect to the shoulder profile line of the land portion is in a range of 0.05 mm to 2.0 mm. Thus, by bulging each land portion and setting the bulge amount, the profile shape of the pneumatic tire can be optimized, which is advantageous for improving the wear resistance performance.

  In the present invention, the “tire contact end” means an end in the tire axial direction when a normal load is applied by placing the tire on a normal rim and filling it with normal internal pressure in a vertical state on a plane. The “contact area” is an area between the tire contact ends on both sides in the tire width direction. The “groove area ratio” is a ratio of the total area of grooves formed in the land portion to the area of the land portion in the ground contact region. Specifically, the groove area ratio of the entire ground contact area is the ratio of the total area of all grooves in the ground contact area to the total area of the entire land area included in the ground contact area, and the groove area ratio of the center land area is , The ratio of the total area of grooves in the center land portion (that is, not including the main groove) to the total area of the center land portion included in the ground contact area, and the groove area ratio of the shoulder land portion is included in the ground contact area This is the ratio of the total area of grooves in the shoulder land portion (that is, not including the main groove) to the total area of the shoulder land portion. The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, a standard rim for JATMA, “Design Rim” for TRA, or ETRTO. Then, “Measuring Rim” is set. “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. The maximum air pressure is JATMA, and the table “TIRE ROAD LIMITS AT VARIOUS” is TRA. The maximum value described in “COLD INFRATION PRESURES”, “INFLATION PRESURE” for ETRTO, is 180 kPa when the tire is a passenger car. “Regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. If JATMA, the maximum load capacity, and if TRA, the table “TIRE ROAD LIMITS AT VARIOUS” The maximum value described in “COLD INFORATION PRESSURES” is “LOAD CAPACITY” if it is ETRTO, but if the tire is a passenger car, the load is equivalent to 88% of the load.

1 is a meridian cross-sectional view of a pneumatic tire according to an embodiment of the present invention. 1 is a front view showing a tread surface of a pneumatic tire according to an embodiment of the present invention. It is a front view which expands and shows a part of shoulder land part of FIG. It is a perspective view which expands and shows a part of shoulder land part of FIG. It is a front view which shows the tread surface of the pneumatic tire which consists of another embodiment of this invention. It is a front view which expands and shows a part of shoulder land part of FIG. It is a perspective view which expands and shows a part of shoulder land part of FIG. FIG. 6 is a meridian end view showing a tread surface of a pneumatic tire according to another embodiment of the present invention.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

  In FIG. 1, the symbol CL represents the tire equator. The pneumatic tire T of the present invention includes a tread portion 1, a sidewall portion 2, and a bead portion 3. A carcass layer 4 is mounted between the pair of left and right bead portions 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded back around the bead core 5 disposed in each bead portion 3 from the vehicle inner side to the outer side. A bead filler 6 is disposed on the outer periphery of the bead core 5, and the bead filler 6 is wrapped by the main body portion and the folded portion of the carcass layer 4. On the other hand, a plurality of layers (two layers in FIG. 1) of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. Each belt layer 7 includes a plurality of reinforcing cords that are inclined with respect to the tire circumferential direction, and is disposed so that the reinforcing cords cross each other between the layers. In these belt layers 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in a range of, for example, 10 ° to 40 °. Further, a belt reinforcing layer 8 is provided on the outer peripheral side of the belt layer 7. The belt reinforcing layer 8 includes an organic fiber cord oriented in the tire circumferential direction. In the belt reinforcing layer 8, the organic fiber cord has an angle with respect to the tire circumferential direction set to, for example, 0 ° to 5 °.

  The present invention is applied to such a general pneumatic tire, but its cross-sectional structure is not limited to the basic structure described above.

  As shown in FIG. 2, a plurality of (three in FIG. 2) main grooves 10 extending in the tire circumferential direction are provided on a tread surface 9 that is an outer surface of the tread portion 1. Specifically, the main groove 10 includes one center main groove 11 positioned on the tire equator CL and a pair of outer main grooves 12 positioned on both outer sides in the tire width direction of the center main groove 11. . Since there are only three main grooves 10 provided in the embodiment of FIG. 2, the outer main groove 12 becomes the main groove 10 located on the outermost side in the tire width direction. A plurality of land portions (a center land portion 13 and a shoulder land portion 14 described later) are partitioned by these main grooves 10 (the center main groove 11 and the outer main groove 12).

  In the present invention, the shape of the center main groove 11 is not particularly limited, but in the embodiment of FIG. 2, the center main groove 11 extends in a zigzag shape while having a see-through portion. The main groove 10 having such a shape is advantageous in improving the wet performance because an excellent drainage performance can be obtained by the see-through portion, and an edge effect can be obtained due to the zigzag shape.

  In the present invention, the shape of the center land portion 13 formed between the pair of outer main grooves 12 is not particularly limited, but in the embodiment of FIG.

  The center land portion 13 is further divided into two portions by the center main groove 11. These portions are substantially point-symmetric with respect to arbitrary points on the tire equator CL. On the center main groove 11 side of the center land portion 13, a plurality of width direction grooves 15 that communicate with the center main groove 11 and terminate in the center land portion 13 are provided. Further, a plurality of short sipes 16 (one on each side in the tire circumferential direction of the width direction groove 15) that communicate with the center main groove 11 on both sides in the tire circumferential direction of the width direction groove 15 and terminate in the center land portion 13. Is provided along the widthwise groove 15. One of the width direction groove 15 and the pair of short sipes 16 communicates with a zigzag-shaped portion of the center main groove 11 that is inclined with respect to the tire circumferential direction (the longer one). The other communicates with the zigzag bent portion of the center main groove 11. On the outer main groove 12 side of the center land portion 13, a plurality of width direction grooves 17 that communicate with the outer main groove 12 and terminate in the center land portion 13 are provided. A circumferential narrow groove 18 extending in the tire circumferential direction is provided at the end portion of each widthwise groove 17 so as to connect the end portions. The portion of the circumferential narrow groove 18 that connects the end portions of the widthwise groove 17 extends substantially parallel to the portion of the center main groove 11 where the widthwise groove 15 is provided. A substantially parallelogram-shaped hole 19 is provided at a portion where the width direction groove 17 and the circumferential direction narrow groove 18 are connected. The outer main groove 12 side of the portion defined by the width direction groove 17 and the circumferential direction narrow groove 18 in the center land portion 13 communicates with the outer side main groove 12 while communicating with the circumferential direction narrow groove 18. Instead, a plurality of (three in each figure) short sipes 20 that terminate in the center land portion 13 are provided along the width direction groove 17. The sipe described above (short sipe 16, 20 and shoulder sipe 23B, communication sipe 24 described later) has a groove width and a groove depth smaller than various grooves, and the groove width is, for example, 0.1 mm to 1.. It is a fine groove having a groove depth of, for example, 2.0 mm to 8.5 mm at 0 mm.

  As shown in FIGS. 2 and 3, the shoulder land portion 14 formed on the outer side in the tire width direction of the outer main groove 12 has a plurality of recessed portions 21 on the side surface on the outer main groove 12 side at intervals in the tire circumferential direction. Is provided. The shape of each recess 21 when viewed from the tread side is not particularly limited. In order to effectively reduce the wear energy with respect to the shoulder land portion 14 during traveling and to improve the wear resistance, FIG. As shown in FIG. Specifically, the side surface of the shoulder land portion 14 configured in parallel to the tire circumferential direction is configured to be parallel to the side surface of the shoulder land portion 14 (that is, parallel to the tire circumferential direction). It is good to comprise by 21 A of made recessed surfaces, and the connection surface 21B which connects this recessed surface 21A and the side surface of the shoulder land part 14. FIG. At this time, the recessed surface 21 </ b> A is the most recessed position with respect to the side surface of the shoulder land portion 14. Further, as shown in FIG. 4, the recess 21 is configured such that the side wall of the shoulder land portion 14 is recessed in a shape (trapezoidal shape in the illustrated example) when viewed from the tread side to the groove bottom side of the outer main groove 12. Is done. The depth D1 of the hollow portion 21 is, for example, 50% to 100% of the groove depth GD of the main groove 10 (outer main groove 12) facing the side wall of the land portion (shoulder land portion 14) where the hollow portion 21 is formed. It is.

  A plurality of holes 22 are provided in the tread surface of the shoulder land portion 14 at intervals in the tire circumferential direction. In particular, in the example of FIG. 2, the plurality of holes 22 are arranged in a line at intervals in the tire circumferential direction. The shape of each hole 22 when viewed from the tread side is not particularly limited, and the illustrated trapezoidal shape, parallelogram shape, quadrangular shape, elliptical shape, circular shape, semicircular shape, crescent shape, and the like can be adopted. . As shown in FIG. 4, the hole 22 is also formed in a columnar shape in which the shape when viewed from the tread surface side is maintained in the depth direction, like the recessed portion 21. The depth D2 of the hole 22 is, for example, 50% to 100% of the groove depth GD of the main groove 10 (outer main groove 12) adjacent to the land portion (shoulder land portion 14) in which the hole 22 is formed. In addition, it is preferable to provide this hole 22 in the tire width direction inner side from the site | part which actually contacts a road surface at the time of driving | running | working, ie, the contact point E.

  The formation positions of the recess 21 and the hole 22 are shifted in the tire circumferential direction and the tire width direction. In other words, the hole 22 is provided between the recesses 21 adjacent to each other in the tire circumferential direction and at a position that does not overlap with a line passing through the recess 21 and extending in the tire circumferential direction. In particular, in the illustrated example, a plurality of depressions 21 provided at intervals in the tire circumferential direction are provided on the same line extending in the tire circumferential direction, while a plurality of depressions 21 provided at intervals in the tire circumferential direction are provided. The holes 22 are provided on another same line extending in the tire circumferential direction on the outer side in the tire width direction than the depressions 21, and the depressions 21 and the holes 22 are alternately scattered in the tire circumferential direction. .

  Since the recess 21 and the hole 22 are thus provided, the recess 21 partially forms a portion having a large groove area in the outer main groove 12, and the groove area is enlarged over the entire circumference of the tire. In this case, it is possible to sufficiently secure the groove area and improve the drainage performance while avoiding the decrease in the wear resistance performance due to a significant decrease in the ground contact area as in the case of doing so. On the other hand, the width of the shoulder land portion 14 becomes narrower and the rigidity of the portion of the shoulder land portion 14 where the recess portion 21 is formed is narrower than the portion where the recess portion 21 is not formed. By forming the hole 22 at a position shifted in the tire width direction, the difference in rigidity in the tire circumferential direction of the shoulder land portion 14 can be reduced, and the wear life of the shoulder land portion 14 can be extended. Moreover, since this hole 22 can take in the water between the tread of the shoulder land part 14, and a road surface, it is advantageous in improving wet performance. Further, since the shape of the hole 22 as viewed from the tread side is basically maintained in the depth direction, the groove (particularly, a groove having a shape in which the groove depth gradually decreases toward a general end). Compared with, since the shape close to that of a new article is maintained even after the wear, the appearance of the tire in the later stage of wear can be kept good.

  At this time, if the hollow portion 21 and the hole 22 overlap in the tire circumferential direction, the hole 22 is too close to the outer main groove 12, so that the rubber between the hole 22 and the outer main groove 12 becomes thin, and wear resistance is improved. The improvement effect cannot be obtained. When the hollow portion 21 and the hole 22 overlap in the tire width direction, the rigidity of the portion of the shoulder land portion 14 where the hollow portion 21 and the hole 22 are formed is significantly reduced, and the rigidity of the shoulder land portion 14 is made uniform. The effect of improving wear resistance cannot be obtained.

  As shown in FIGS. 2 and 3, the shoulder land portion 14 may be provided with a lug groove 23 </ b> A and a communication sipe 24 that extend in the tire width direction from the width direction outer side of the shoulder land portion 14. When the lug groove 23A is provided, the lug groove 23A does not communicate with the outer main groove 12 and terminates in the shoulder land portion 14, and the termination position is on the inner side in the tire width direction with respect to the tire ground contact end E, and the hole It is preferably a position on the outer side in the tire width direction than 22. In other words, the hole 22 is preferably disposed between the recess 21 and the terminal end of the lug groove 23A. By arranging the hole 22 and the lug groove 23A in this way, the rigidity of the shoulder land portion 14 can be made more effective, which is advantageous for improving the wear resistance.

  Alternatively, as shown in FIGS. 5 to 7, the shoulder land portion 14 may be provided with a shoulder sipe 23 </ b> B and a communication sipe 24 that extend in the tire width direction from the outer side in the width direction of the shoulder land portion 14. When the shoulder sipe 23B is provided, the shoulder sipe 23B does not communicate with the outer main groove 12 and terminates in the shoulder land portion 14, the termination position is on the inner side in the tire width direction from the tire ground contact end E, and the hole It is preferably a position on the outer side in the tire width direction than 22. In other words, the hole 22 is preferably disposed between the recess 21 and the end of the shoulder sipe 23B. By arranging the hole 22 and the shoulder sipe 23B in this manner, the rigidity of the shoulder land portion 14 can be more effectively uniformed, which is advantageous for improving the wear resistance.

  The basic structure of the tread pattern of FIG. 5 is the same as that of the tread pattern of FIG. 2, but in addition to the fact that the lug groove 23A in the tread pattern of FIG. The structure of the center land portion 13 is slightly different. That is, the center land portion 13 in the tread pattern of FIG. 5 is divided into two portions by the center main groove 11 and has a plurality of width direction grooves 15 as in FIG. Short sipes are not provided on both sides in the tire circumferential direction (the short sipes 16 are present in FIG. 2). Further, the center land portion of FIG. 5 is provided with a width direction groove 17, a circumferential direction narrow groove 18, and a hole 19 as in FIG. 2, but is divided into the width direction groove 17 and the circumferential direction narrow groove 18. One short sipe 20 is provided in each of the portions along the width direction groove 17. In other words, the sipe density in the center land portion 13 is smaller in the tread pattern of FIG. 5 than in the tread pattern of FIG. 2 is compared with the tread pattern of FIG. 5, the width of the center land portion 13 in the tread pattern of FIG. 5 is larger than the width of the center land portion 13 of the tread pattern of FIG.

  FIGS. 6 to 7 show the main part of FIG. 5 in an enlarged manner, but basically have the same structure except that the lug groove 23A of FIGS. 3 to 4 is a shoulder sipe 23B.

  Thus, when providing the lug groove 23A or the shoulder sipe 23B, the distance La from the tire circumferential direction center of the hole 22 to the center line of the lug groove 23A or the shoulder sipe 23B is set to the center of the recess 21 adjacent in the tire circumferential direction. The distance Lb is preferably 20% to 80%, more preferably 40% to 60%. Thus, by arranging the hole 22, the recessed portion 21, and the lug groove 23A or the shoulder sipe 23B, the rigidity of the shoulder land portion 14 can be more effectively uniformed in the tire circumferential direction, and the wear resistance performance can be improved. It will be advantageous to improve. At this time, if the distance La is smaller than 20% of the distance Lb, the hole 22 and the lug groove 23A or the shoulder sipe 23B are too close to each other, making it difficult to make the rigidity uniform. If the distance La is larger than 80% of the distance Lb, the hole 22 and the lug groove 23A or the shoulder sipe 23B are separated from each other, so that it is difficult to make the rigidity of the shoulder land portion 14 uniform in the tire circumferential direction.

  On the other hand, regardless of the presence or absence of the lug groove 23A or the shoulder sipe 23B, the hole 22 has a distance Lc from the center of the tire width direction to the tire ground contact edge E from the side surface of the shoulder land portion 14 to the tire ground contact edge E. (In other words, the width SW of the shoulder land portion 14 to the tire ground contact edge E) is preferably 20% to 80%, more preferably 40% to 60%. By arranging the holes 22 in this manner, the rigidity of the shoulder land portion can be more effectively equalized in the tire circumferential direction, which is advantageous for improving the wear resistance. At this time, if the distance Lc is smaller than 20% of the width SW, the hole 22 is too close to the tire ground contact E, so that it is difficult to sufficiently equalize the rigidity of the portion actually installed when the shoulder land portion 14 is running. Become. If the distance Lc is larger than 80% of the width SW, the hole 22 is too close to the outer main groove 12, so that it is difficult to sufficiently improve the wear resistance.

  When the communication sipes 24 are provided, each of the communication sipes 24 is configured such that one end thereof communicates with the hole 22 and the other end opens to the outer side in the tire width direction of the shoulder land portion 14. Is preferred. The communication sipe 24 having such a shape does not significantly reduce the rigidity of the shoulder land portion 14 unlike a groove, but the rigidity can be adjusted to an appropriate level in order to equalize the rigidity of the shoulder land portion 14. Furthermore, since the water taken into the hole 22 can be drained to the outside in the tire width direction, it is effective to achieve both wear resistance and wet performance. At this time, in order to more effectively equalize the rigidity of the shoulder land portion 14 in the tire circumferential direction, the communication sipe 24 is communicated from the center of the hole 22 to a position within 25% of the circumferential length L2 of the hole 22. Good. 4 and 7, the depth of the communication sipe 24 is smaller than the depth of the hole 22. In order to obtain the above-described effect by the communication sipe 24 more effectively, the communication sipe 24 is preferably used. The depth of 24 may be 50% to 80% of the depth D2 of the hole 22.

  In addition to the communication sipe 24, as shown in FIGS. 2 to 7, a short sipe 25 communicating with the outer main groove 12 may be provided. The shape and the number of the short sipes 25 provided on the outer main groove 12 side are not particularly limited. For example, as illustrated, the short sipes 25 are inclined with respect to the tire width direction between the adjacent recess portions 21 and are within the shoulder land portion 14. A plurality of (two in the illustrated example) short sipes 25 that terminate may be provided.

  The size of the recess portion 21 is not particularly limited, but the recess amount W1 with respect to the side surface of the shoulder land portion 14 (that is, the length from the side surface of the shoulder land portion 14 to the recess surface 21A) is the groove width GW of the outer main groove 12. Is preferably 20% to 80%, more preferably 40% to 60%. By defining the size of the recess 21 in this way, wet performance can be improved while maintaining wear resistance. At this time, if the dent amount W1 is smaller than 20% of the groove width GW of the outer main groove 12, the dent portion 21 is too small, so that the groove area cannot be sufficiently increased and the effect of improving the wet performance is sufficiently obtained. I can't. If the depression amount W1 is larger than 80% of the groove width GW of the outer main groove 12, the groove area becomes too large and the wear resistance is deteriorated.

  The tire circumferential direction length L1 of the hollow part 21 is preferably 20% to 180%, more preferably 50% to 100% of the length Ld between the hollow parts 21 adjacent in the tire circumferential direction. By defining the size of the recess portion 21 in this way, the rigidity of the shoulder land portion can be more effectively made uniform in the tire circumferential direction, which is advantageous for improving the wear resistance. At this time, if the circumferential length L1 of the recesses 21 is smaller than 20% of the length Ld between the recesses 21, the recesses 21 become small, so that the groove area cannot be increased sufficiently and the wet performance is improved. The improvement effect cannot be obtained sufficiently. If the circumferential length L1 of the hollow portion 21 is larger than 180% of the length Ld between the hollow portions 21, the hollow portion is too large, so that the rigidity of the shoulder land portion 14 is lowered and the wear resistance is maintained at a high level. Becomes difficult.

  The size of the hole 22 is not particularly limited, but the area S2 of the shoulder 22 on the shoulder land portion 14 of the hole 22 is preferably 30% to 300%, more preferably 60% of the area S1 of the shoulder land portion 14 of the recessed portion 21. % To 150% is preferable. By defining the area S2 of the hole 22 with respect to the area S1 of the hollow portion 21 in this way, it is advantageous to achieve both wear resistance performance and wet performance. At this time, if the area S2 of the hole 22 is smaller than 30% of the area S1 of the recessed portion 21, the hole 22 is too small to obtain the effect of providing the hole 22 sufficiently. If the area S2 of the hole 22 is larger than 300% of the area S1 of the hollow portion 21, the rigidity of the shoulder land portion 14 becomes too low at the portion where the hole 22 is provided, so that the rigidity of the shoulder land portion 14 can be made uniform. It becomes difficult. In addition, the area S1 of the hollow portion 21 is an area of a portion surrounded by a line obtained by extending the side surface of the shoulder land portion 14, the hollow surface 21A, and the connecting surface 21B.

  The shape of the hole 22 can be various shapes as described above. Preferably, the length L2 of the hole 22 in the tire circumferential direction is the length of the hole 22 in the tire width direction (that is, the width W2 of the hole 22). It is good that it is 1 to 5 times. By defining the size of the hole 22 in this way, the rigidity of the shoulder land portion 14 can be more effectively uniformed in the tire circumferential direction, which is advantageous for improving the wear resistance. At this time, if the length L2 of the hole 22 in the tire circumferential direction is smaller than one time the width W2 of the hole 22, that is, if the hole 22 has a flat shape in the tire circumferential direction, Since the rigidity of the land portion 14 cannot be sufficiently lowered, it is difficult to make the shoulder land portion 14 uniform in rigidity. If the length L2 of the hole 22 in the tire circumferential direction is larger than five times the width W2 of the hole 22, that is, if the hole 22 has a shape that is significantly longer in the tire circumferential direction, Since the rigidity of the portion 14 is significantly reduced, it is difficult to make the rigidity of the shoulder land portion 14 uniform.

  As described above, in the present invention, various grooves and the like are provided on the tread surface 9, but in order to ensure a sufficient ground contact area and maintain wear resistance, the groove area ratio of the entire ground contact region is 10%. It is preferable to set it in a range of ˜20%. Further, the ratio of the groove area of the main groove 10 to the total groove area included in the ground contact region is set in a range of 60% to 70%, and the groove area ratio of the shoulder land portion 14 is set to the groove area of the center land portion 13. It is preferable to make it smaller than the ratio. By setting in this way, the groove area (groove area ratio) is optimized, which is advantageous for improving wear resistance performance while obtaining sufficient wet performance. At this time, if the groove area ratio of the entire grounding region is smaller than 10%, sufficient wet performance cannot be maintained. If the groove area ratio of the entire grounding region is larger than 20%, it is difficult to sufficiently improve the wear resistance. If the ratio of the groove area of the main groove 10 is smaller than 60%, it is difficult to maintain the wet performance. When the ratio of the groove area of the main groove 10 is larger than 70%, it is difficult to sufficiently improve the wear resistance. When the groove area ratio of the shoulder land portion 14 is larger than the groove area ratio of the center land portion 13, it is difficult to sufficiently improve the wear resistance.

  As shown in FIG. 8, in the tire meridian section, each land portion (center land portion 13 and shoulder land portion 14) can be bulged with respect to profile lines Lc and Ls described later. Specifically, while the center land portion 13 is bulged with respect to the center profile line Lc formed of the center reference arc passing through each edge point on the tread surface of the center land portion 13, the edge on the tread surface of the shoulder land portion 14 is expanded. The shoulder land portion 14 is preferably bulged with respect to a shoulder profile line Ls formed of a shoulder reference arc that is in contact with the center reference arc through the point. At this time, the bulging amount H with respect to the corresponding profile line (center profile line Lc or shoulder profile line Ls) of each land portion (center land portion 13 and shoulder land portion 14) is in the range of 0.05 mm to 2.0 mm, respectively. It is preferable to do. Thus, by optimizing the profile shape of the tread surface of the tread portion 1, the contact pressure distribution can be optimized, which is advantageous for improving the wear resistance. At this time, if the bulging amount H is smaller than 0.05 mm, there is no substantial difference from the case where the land portion does not bulge, and the effect of bulging the land portion cannot be obtained. When the bulging amount H is larger than 2.0 mm, the contact pressure distribution cannot be optimized and the wear resistance performance cannot be improved.

The tire size is 185 / 65R15, has the basic structure illustrated in FIG. 1, is based on the tread pattern of FIG. 2 or FIG. 5, and the shape of the shoulder land portion is the presence or absence of a depression, the presence or absence of a hole, the depression Position in the circumferential direction between the hole and the hole, position in the width direction between the recess and the hole, type of the width direction groove formed in the shoulder land portion (lug groove or sipe), end of the lug groove or shoulder sipe (width direction groove end) Position, relationship between lug groove or shoulder sipe end (width direction groove end) and main groove (with or without communication), position relationship between lug groove or shoulder sipe end (width direction groove end) and hole, ground end and hole , The ratio W1 / GW of the width direction length W1 of the recess to the groove width GW of the outer main groove, the ratio S2 / S1 of the hole area S2 to the area S1 of the recess, the recess in the tire circumferential direction Depression Direction (whether parallel to the tire circumferential direction), the relationship between the sipe and the hole (communication), the position of the sipe with respect to the circumferential center of the hole (ratio to the circumferential length of the hole), adjacent depressions Ratio La / Lb of the distance La between the circumferential center of the lug groove and the circumferential center of the hole with respect to the center-to-center distance Lb, and the length from the ground contact edge to the widthwise center of the hole with respect to the width SW of the shoulder land portion Lc ratio Lc / SW, ratio L1 / Ld of the circumferential length L1 of the recess to the length Ld between adjacent recesses, ratio L2 / W2 of the circumferential length L2 of the hole to the width W2 of the hole The ratio of the groove area of the main groove to the total groove area included in the ground contact area, the ratio of the groove area ratio of the entire ground contact area, the size of the groove area ratio of the shoulder land portion and the center land portion, the swelling of the land portion with respect to the profile line Set output amount as shown in Tables 1-5. Conventional Example 1, Comparative Examples 1 to 2 were produced 59 kinds of pneumatic tires of Examples 1 to 56 (Note that Examples 20 communicating sipe is non communicating relative holes are reference examples).

  In Tables 1 to 5, lug grooves and shoulder sipes formed in the shoulder land portions are collectively indicated as “width direction grooves”. That is, in the column of “type of width direction groove formed in shoulder land portion” in Tables 1 to 5, when “width direction groove” is a lug groove (conventional example 1, comparative examples 1 and 2, and example 1) , 3 to 56) is displayed as “lag groove”, and “sipe” is displayed when the “width direction groove” is a shoulder sipe (Example 2). That is, Conventional Example 1, Comparative Examples 1 and 2, and Examples 1 and 3 to 56 are based on the tread pattern of FIG. 2, and Example 2 is based on the tread pattern of FIG. Further, in the other column regarding “width direction groove”, the structure of the lug groove or shoulder sipe provided in each example is shown.

  In the column of “groove area ratio relationship” in Tables 1 to 10, “Ce> Sh” when the groove area ratio of the shoulder land portion is smaller than the groove area ratio of the center land portion, the groove area ratio of the center land portion Is smaller than the groove area ratio of the shoulder land portion, “Ce <Sh” is indicated.

  About these 59 types of pneumatic tires, wear resistance performance and wet performance were evaluated by the following evaluation methods, and the results are shown in Tables 1 to 5.

Wear resistance performance Each test tire is mounted on a wheel with a rim size of 15 x 5.5 J, mounted on a 2000 cc FF sedan passenger car (test vehicle) with an air pressure of 200 kPa, run on a monitor, and measure the distance traveled to total wear did. The evaluation results are shown as an index with the value of Conventional Example 1 being 100. The larger the index value, the longer the distance traveled until total wear, and the better the wear resistance. When the index value is “103” or more, the wear resistance is particularly good.

Wet performance Each test tire is assembled to a wheel with a rim size of 15 x 5.5 J, and the air pressure is set to 200 kPa. It was measured. The evaluation results are shown as an index with the reciprocal of the value of Conventional Example 1 as 100. A larger index value means shorter braking distance and better wet performance. When the index value is “103” or more, the wet performance is particularly good.

  As is clear from Tables 1 to 5, all of Examples 1 to 56 have improved wear resistance and wet performance as compared to Conventional Example 1. Further, in Examples 1 to 56, since a hole that maintains a shape close to that of a new article is formed even after wear, the tire appearance was kept good even in the later stage of wear. On the other hand, none of Comparative Examples 1 and 2 in which the hollow portion and the hole overlap in the circumferential direction or the width direction has an effect of improving the wear resistance performance.

  Although not shown in Tables 1 to 5, in Example 2 (a mode in which a shoulder sipe is formed on the shoulder land portion), each parameter is changed in the same manner as in Examples 3 to 56 for Example 1. The abrasion resistance performance and the wet performance were the same as those of Examples 3 to 56 for Example 1 with respect to Example 2. That is, in Example 2, the wear resistance performance is 2 points higher in index value than in Example 1, and the wet performance is 2 points lower in index value. Therefore, each parameter is changed in the same manner as in Examples 3 to 56 for Example 1. As a result of the evaluation, the wear resistance index values of Examples 3 to 56 were increased by 2 points, and the wet performance index value was decreased by 2 points.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt reinforcement layer 9 Tread surface 10 Main groove 11 Center main groove 12 Outer main groove 13 Center land part 14 Shoulder land part 15 Width direction Groove 16 Short sipe 17 Width direction groove 18 Circumferential narrow groove 19 Hole 20 Short sipe 21 Recessed portion 21A Recessed surface 21B Connection surface 22 Hole 23A Lug groove 23B Sipe 24 Communication sipe 25 Short sipe CL Tire equator E Grounding end

Claims (13)

In the pneumatic tire in which at least three main grooves extending in the tire circumferential direction are provided on the tread surface, and a plurality of rows of land portions are defined by the main grooves,
A plurality of recesses are spaced apart in the tire circumferential direction on the side surface on the outermost main groove side of the shoulder land portion formed on the outer side of the outermost main groove located on the outermost side of the main groove in the tire width direction. And a plurality of holes are provided at intervals in the tire circumferential direction on the tread surface of the shoulder land portion , and the recessed portion and the hole are arranged shifted in the tire circumferential direction and the tire width direction , A plurality of communicating sipes extending in the tire width direction are formed in the shoulder land portion, one end portion of each communicating sipes communicates with the hole, and the other end portion of each communicating sipes is the shoulder land portion. A pneumatic tire characterized by opening outward in the tire width direction .   While the hole is disposed in the tire width direction inner side than the tire ground contact end and in the tire width direction outer side than the hollow portion, a plurality of lug grooves extending in the tire width direction are spaced in the tire circumferential direction on the shoulder land portion And the lug groove terminates without communicating with the outermost main groove at a position inside the tire ground contact end in the tire width direction and outside the hole in the tire width direction. The pneumatic tire according to claim 1, wherein   While the hole is disposed in the tire width direction inner side than the tire ground contact end and the tire width direction outer side than the hollow part, a plurality of sipes extending in the tire width direction are spaced apart in the tire circumferential direction on the shoulder land portion. The sipe terminates without communicating with the outermost main groove at a position on the inner side in the tire width direction than the tire ground contact end and on the outer side in the tire width direction with respect to the hole. The pneumatic tire according to claim 1.   The pneumatic tire according to any one of claims 1 to 3, wherein a hollow amount of the hollow portion with respect to a side surface of the shoulder land portion is 20% to 80% of a groove width GW of the outermost main groove. .   5. The pneumatic according to claim 1, wherein an area of the hole on the tread of the shoulder land portion is 30% to 300% of an area of the depression on the tread of the shoulder land portion. tire.   While the side surface of the shoulder land portion is parallel to the tire circumferential direction, the recess portion connects the recess surface parallel to the side surface of the shoulder land portion, and the recess surface and the side surface of the shoulder land portion. The pneumatic tire according to any one of claims 1 to 5, comprising a connecting surface. The pneumatic tire according to any one of claims 1 to 6, wherein the communication sipe communicates with a position within 25% of a circumferential length of the hole from the center of the hole. Claim 2-7, wherein the distance from the tire circumferential direction center of the hole to the center line of the lug groove is 20% to 80% of the distance between the centers of the recess adjacent in the tire circumferential direction The pneumatic tire according to any one of the above. Any of claims 1-8, wherein the distance from the tire width direction center of the hole to the tire ground contact edge is 20% to 80% of the distance from the side of the shoulder land portion to the tire ground contact edge The pneumatic tire according to Crab. The pneumatic tire according to any one of claims 1 to 9 , wherein a length of the hollow portion in the tire circumferential direction is 20% to 180% of a length between the hollow portions adjacent in the tire circumferential direction. . The pneumatic tire according to any one of claims 1 to 10 , wherein a length of the hole in a tire circumferential direction is 1 to 5 times a length of the hole in a tire width direction. While the ratio of the groove area of the main groove to the total groove area included in the grounding region is 60% to 70%, the groove area ratio of the entire grounding region is 10% to 20%, and the shoulder land portion the pneumatic tire according to any one of claims 1 to 11, the groove area ratio of being less than the groove area ratio of the center land portion. In the tire meridian cross section, the center land portion bulges against a center profile line consisting of a center reference arc passing through each edge point on the tread of the center land portion located inside the outermost main groove, The shoulder land portion is bulged with respect to a shoulder profile line formed of a shoulder reference arc that contacts the center reference arc through an edge point on the tread of the shoulder land portion, and the center land portion bulges with respect to the center profile line. The pneumatic tire according to any one of claims 1 to 12 , wherein an amount and a bulge amount of the shoulder land portion with respect to the shoulder profile line are in a range of 0.05 mm to 2.0 mm, respectively.

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