JP2015189349A - pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving noise performance while achieving both of steering stability on a dry road surface and running performance on a wet road surface.SOLUTION: In a pneumatic tire which has at least four main grooves 11 and for which the mounting direction with respect to a vehicle is designated, an outer shoulder lug groove 24 which is not opened to the main grooves 11 and an outer shoulder siping 25 which is opened to the main grooves 11 are alternately disposed in the tire circumferential direction on an outer shoulder land part 18, and a circumferential thin groove 26 which intersects the outer shoulder lug groove 24 and the outer shoulder siping 25 is disposed, a center line of the outer shoulder lug groove 24 and a center line of the outer shoulder siping 25 are shifted in the tire circumferential direction respectively with the circumferential thin groove 26 as a boundary, a shift amount of the outer shoulder lug groove 24 is set to 0.5 to 5 times of a groove width of the outer shoulder lug groove 24 and a shift amount of the outer shoulder siping 25 is set to 0.5 to 5 times of a groove width of the outer shoulder siping 25.

Description

  The present invention relates to a pneumatic tire having at least four main grooves extending in the tire circumferential direction on a tread surface. More specifically, the present invention relates to noise while maintaining both steering stability performance on a dry road surface and running performance on a wet road surface. The present invention relates to a pneumatic tire capable of improving performance.

  In recent years, with the progress of road maintenance and higher performance of vehicles, for pneumatic tires, the driving performance on dry roads (dry performance) and the driving performance on wet roads (wet performance) during high-speed driving There is a strong demand to improve noise performance while achieving compatibility.

  Generally, as a method for improving wet performance, in addition to a main groove extending in the tire circumferential direction on the tread surface of the tire, a lug groove or sipe extending in the tire width direction is formed to ensure drainage. . However, in such a method, since the rigidity of the land portion formed on the tread surface is lowered, there is a problem that it is difficult to ensure the dry performance and the noise performance is deteriorated.

  Conventionally, as a measure to improve noise performance while achieving both dry performance and wet performance, it has been proposed to specify the direction of the lug groove and its arrangement after specifying the mounting direction of the tire on the vehicle. (For example, refer to Patent Document 1).

  However, in the structure of Patent Document 1, in order to ensure drainage performance, particularly in the shoulder land portion that is on the outside with respect to the vehicle when the vehicle is mounted, in addition to the lug groove that terminates in the land portion, And a sipe that communicates with the main groove. However, the combination of these sipe and lug groove is substantially a groove whose one end communicates with the main groove and the other end opens toward the outside in the tire width direction of the shoulder land portion (outside the vehicle). Therefore, there is a problem that there is an adverse effect on noise radiated outside the vehicle. In addition, the land portion between the main groove adjacent to the shoulder land portion and the circumferential narrow groove provided in the shoulder land portion has only a sipe groove extending in the tire width direction. The dry performance and wet performance in this portion are not necessarily high, and there is a problem that it is difficult to sufficiently improve the dry performance and wet performance of the entire tire by this land portion. Therefore, the sipe extending in the tire width direction from the end of the lug groove that terminates in the shoulder land portion may be disconnected from the main groove, or a groove extending in the tire width direction may be added to the above-described land portion portion. Although it is conceivable, simply remodeling these elements will break the balance of the shape and arrangement of the lug grooves and sipes, so the dry performance, wet performance, and noise performance that were obtained with the structure of Patent Document 1 will also be obtained. It becomes impossible. Therefore, further improvement for improving noise performance is demanded while achieving both dry performance and wet performance.

JP 2008-162390 A

  An object of the present invention is to provide a pneumatic tire capable of improving noise performance while achieving both stable driving performance on a dry road surface and traveling performance on a wet road surface.

  In order to achieve the above object, the pneumatic tire of the present invention has at least four main grooves extending in the tire circumferential direction on the tread surface, and a plurality of circumferential land extending in the tire circumferential direction between adjacent main grooves. A pneumatic tire in which a shoulder land portion is defined on the outer side in the tire width direction of each of the outermost main grooves in the tire width direction and the mounting direction with respect to the vehicle is specified. The outer shoulder that extends in the tire width direction to the outer shoulder land that is outside the vehicle when mounted on the vehicle, and terminates in the outer shoulder land without communicating with the main groove adjacent to the outer shoulder land. Lug grooves and outer shoulder sipes extending in the tire width direction and communicating with the main groove adjacent to the outer shoulder land portion are alternately provided in the tire circumferential direction, and the front A groove width and a groove depth smaller than the main groove, extending in the tire circumferential direction, and provided with a circumferential narrow groove intersecting the outer shoulder lug groove and the outer shoulder sipe, and the outer shoulder shouldered by the circumferential narrow groove. The center line of the lug groove and the center line of the outer shoulder sipe are shifted in the tire circumferential direction, and the shift amount of the center line of the outer shoulder lug groove is 0.5 times or more and five times the groove width of the outer shoulder lug groove. The amount of deviation of the center line of the outer shoulder sipe is set to 0.5 to 5 times the groove width of the outer shoulder sipe.

  In the present invention, as described above, since the outer shoulder lug groove is not connected to the main groove adjacent to the outer shoulder land portion, noise performance and dry performance can be improved. On the other hand, since the outer shoulder sipe that opens to the main groove adjacent to the outer shoulder land portion is provided, the wet performance is concerned that the outer shoulder lug groove may be deteriorated by discontinuing the main groove. Can be complemented. Furthermore, since the circumferential narrow groove intersects both the outer shoulder lug groove and the outer shoulder sipe, the circumferential narrow groove, the outer shoulder lug groove, and the outer shoulder sipe form a series of water passages, and drainage is promoted. Therefore, the wet performance can be further improved. In addition, the outer shoulder lug groove and the outer shoulder sipe are displaced in the tire circumferential direction within the predetermined deviation amount at the circumferential narrow groove, respectively, reducing the outside noise while maintaining a high drainage performance. Noise performance can be improved. Therefore, dry performance, wet performance, and noise performance can be improved in a well-balanced manner, and these performances can be made highly compatible.

  In the present invention, of the corners formed by the outer shoulder lug groove and the circumferential narrow groove in the outer shoulder land portion, chamfering is performed on a portion where the angle formed by the outer shoulder lug groove and the circumferential narrow groove is an acute angle. It is preferable to make the chamfering amount of the outer chamfered portion located outside the circumferential narrow groove in the tire width direction larger than the chamfering amount of the inner chamfered portion located inside the circumferential narrow groove in the tire width direction. By chamfering in this way, the water can easily flow in the lug groove, and the drainage performance can be further improved. Moreover, uneven wear can be suppressed.

  At this time, it is preferable that the chamfering depth of the inner chamfered portion and the outer chamfered portion is 80% or more of the groove depth of the circumferential narrow groove. By setting the chamfering depth in this way, excellent drainage performance can be maintained until the end of wear.

  In the present invention, it is preferable that the outer shoulder sipe has a three-dimensional structure that is a straight line or a curved line having no bending point on the tread surface side and a meandering shape having a bending point on the groove bottom side. Since the edge effect by sipe can be obtained while preventing the rigidity of the outer shoulder land portion from excessively decreasing due to the sipe having a bent portion in this way, drainage performance and dry performance can be further improved. . Also, due to the difference in structure between the tread surface side and the groove bottom side, the zigzag sipe, which is harder to reduce the rigidity than the straight sipe, is more difficult to lower than the straight sipe in the later stage of wear when the rigidity of the land portion is lower than the initial wear. Since it appears on the surface and exhibits its effect, the rigidity of the land portion can be effectively maintained.

  In the present invention, it is preferable to chamfer all the edge portions adjacent to the main grooves of the circumferential land portion and the shoulder land portion. This is advantageous for suppressing uneven wear of the circumferential land portion and the shoulder land portion.

  In the present invention, it is preferable to provide a plurality of dimples in an end region on the outer side in the tire width direction of the outer shoulder land portion. As a result, it is possible to reduce running resistance and improve fuel efficiency during vehicle running.

  In the present invention, a plurality of inclined grooves extending while inclining with respect to the tire circumferential direction are provided in the central land portion located on the tire equator among the circumferential land portions, and one end of the inclined groove is provided to the vehicle when the vehicle is mounted. While opening the main groove on the inner side, the other end of the inclined groove is terminated in the central land portion without opening the main groove on the outer side with respect to the vehicle when the vehicle is mounted. The first inclined portion having a relatively large angle with respect to the direction may be formed, and the second inclined portion having a relatively small angle with respect to the tire circumferential direction may be formed on the end side of the inclined groove. By setting it as such a specification, since the other end of an inclined groove | channel terminates in a central land part, it can suppress that the tire noise generated in the area | region inside a vehicle of a tread part is radiated | emitted to the vehicle outer side. Moreover, the inclined groove has a first inclined portion having a relatively large angle with respect to the tire circumferential direction on the opening end side, and a second inclined portion having a relatively small angle with respect to the tire circumferential direction on the terminal end side. Therefore, the second inclined portion effectively takes in water near the central land portion, and the taken-in water is guided into the main groove through the first inclined portion, so that noise performance and wet performance can be improved. Will be advantageous.

  At this time, the inclination angle of the first inclined portion of the inclined groove with respect to the tire circumferential direction is preferably 45 ° to 90 °, and the inclination angle of the second inclined portion of the inclined groove with respect to the tire circumferential direction is preferably 0 ° to 30 °. . By setting it as such a specification, the drainage performance by an inclined groove | channel can fully be ensured.

  Further, chamfering is performed on a portion of the central land portion formed by the first inclined portion of the inclined groove and the main groove opened by the first inclined portion, where the inclined angle of the first inclined portion is an acute angle. It can also be made to the specifications. By setting it as such a specification, while being able to suppress the uneven wear of an acute angle part, the drainage property by an inclination groove | channel can be improved.

  Furthermore, the specification can be such that the radius of curvature at the groove bottom of the inclined groove and the groove wall angle with respect to the normal direction of the tread surface are larger on the opening end side than on the terminal end side of the inclined groove. By setting it as such a specification, the drainage by an inclined groove | channel can be improved.

  Furthermore, it is also possible to make the specification such that the distance from the end of the inclined groove to the end on the outer side with respect to the vehicle when the vehicle is mounted on the central land is 20% to 50% of the width of the central land. By setting it as such a specification, the drainage property by an inclined groove | channel can be ensured, maintaining the rigidity of a central land part.

  Furthermore, the inner intermediate land portion is located on the extension line of the first inclined portion of the inclined groove on the inner intermediate land portion adjacent to the side that becomes the inner side with respect to the vehicle when the vehicle in the central land portion is mounted among the circumferential land portions. A plurality of inner intermediate lug grooves penetrating through the inner intermediate land portion may be provided, and the inner intermediate land portion may be configured as a block row composed of a plurality of blocks. By setting it as such a specification, the running performance on a wet road surface can be further improved.

  Further, in the outer land portion adjacent to the outer side of the circumferential land portion on the outer side with respect to the vehicle when the central land portion is mounted on the vehicle, located on the extension line of the first inclined portion of the inclined groove, The outer intermediate lug groove may be provided with a plurality of outer intermediate lug grooves that are opened in the main groove that becomes the inner side with respect to the vehicle when the vehicle is mounted, and the outer intermediate land portion may be configured as a rib row continuous in the tire circumferential direction. By adopting such a specification, it is possible to further improve the running performance on a wet road surface while suppressing the generation of noise.

  In the present invention, the inner shoulder land portion that extends in the tire width direction to the inner shoulder land portion that is on the inner side with respect to the vehicle when the vehicle is mounted is not opened to the main groove adjacent to the inner shoulder land portion. A plurality of inner shoulder lug grooves that terminate in the inner portion, and a non-end that extends in the tire width direction from the end of the inner shoulder lug groove and terminates in the inner shoulder land portion without opening to the main groove adjacent to the inner shoulder land portion. An opening sipe is provided, and the non-opening sipe adjacent in the tire circumferential direction extends in the tire width direction without being connected to the inner shoulder lug groove, and is open to the main groove adjacent to the inner shoulder land portion. It is also possible to provide a specification in which an opening sipe is provided and a non-opening sipe and an opening sipe are alternately arranged in the tire circumferential direction. By setting it as such a specification, dry performance, wet performance, and noise performance can be improved in a balanced manner in the inner shoulder land portion.

  In the present invention, when the tread portion is divided into a vehicle outer region that is outside the vehicle when the vehicle is mounted and a vehicle inner region that is inside the vehicle when the vehicle is mounted, The groove area ratio can be made larger than the groove area ratio in the vehicle outer region, and the difference between these groove area ratios can be set to 1% point or more. By adopting such a specification, it is possible to further improve the running performance on a wet road surface while suppressing the generation of noise.

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. FIG. 3 is an explanatory view showing a part of an outer shoulder land portion of the pneumatic tire of FIG. 2 in an enlarged manner. FIG. 4 is an explanatory diagram schematically showing a state in which a part of the outer shoulder land portion of FIG. 3 is viewed from the direction of an arrow. FIG. 3 is an explanatory view showing a structure of an outer shoulder sipe of a pneumatic tire according to an embodiment of the present invention. It is explanatory drawing which expands and shows a part of central land part of the pneumatic tire which consists of embodiment of this invention. It is X1-X1 arrow sectional drawing of FIG. It is X2-X2 arrow sectional drawing of FIG.

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

  In FIG. 1, the pneumatic tire T is designated with respect to the mounting direction with respect to the vehicle, the symbol IN is the side that is on the inner side of the vehicle when the vehicle is mounted (hereinafter referred to as the vehicle inner side), Side (hereinafter referred to as the vehicle outside), the symbol CL represents the tire equator. The pneumatic tire T includes a tread portion 1, sidewall portions 2, and bead portions 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 from the tire inner side to the outer side around the bead core 5 disposed in each bead portion 3. 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 and 8 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. Each of the belt layers 7 and 8 includes a plurality of reinforcing cords 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 and 8, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set, for example, in a range of 10 ° to 40 °. Further, a belt reinforcing layer 9 is provided on the outer peripheral side of the belt layers 7 and 8. The belt reinforcing layer 9 includes an organic fiber cord oriented in the tire circumferential direction. In the belt reinforcing layer 9, 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 illustrated in FIG. 2, a plurality of (four in FIG. 2) main grooves 11 extending in the tire circumferential direction are provided on the outer surface of the tread portion 1 of the pneumatic tire of the present invention, that is, the tread surface 10. It has been. The main groove 11 has a groove width of, for example, 5 mm to 10 mm, and a groove depth of, for example, 7 mm to 9 mm. A plurality of (three in FIG. 2) circumferential land portions 12 extending in the tire circumferential direction are defined between adjacent main grooves 11. Among these circumferential land portions 12, the land portion located on the tire equator is the central land portion 13, and the land portion located inside the vehicle with respect to the central land portion 13 is the inner intermediate land portion 14 and the central land portion 13. The land portion located outside the vehicle is referred to as an outer intermediate land portion 15. Further, on both sides of the tire equator CL in the tire width direction, a shoulder land portion 16 is defined on the outer side in the tire width direction of the outermost main groove 11 in the tire width direction. Of these shoulder land portions 16, the land portion located inside the vehicle is referred to as an inner shoulder land portion 17, and the land portion located outside the vehicle is referred to as an outer shoulder land portion 18.

  In the embodiment illustrated in FIG. 2, a plurality of inclined grooves 19 extending while being inclined with respect to the tire circumferential direction are formed in the central land portion 13 at intervals in the tire circumferential direction. The inclined groove 19 has one end opened in the main groove 11 on the vehicle inner side and the other end does not open in the main groove 11 on the vehicle outer side, and terminates in the central land portion 13 at a position on the vehicle inner side than the tire equator CL. doing. The inclined groove 19 has a groove width, for example, 2 mm to 4 mm, and a groove depth, for example, 4 mm to 7 mm. The inclined groove 19 has a bent shape, has an inclined portion 19A (first inclined portion) having a relatively large angle with respect to the tire circumferential direction on the opening end side, and has an angle with respect to the tire circumferential direction relatively on the terminal end side. It has a small inclined part 19B (second inclined part).

  In the embodiment illustrated in FIG. 2, a plurality of inner intermediate lug grooves 20 that are located on the extension line of the first inclined portion 19 </ b> A of the inclined groove 19 and penetrate the inner intermediate land portion 14 are formed in the inner intermediate land portion 14. Has been. The inner intermediate lug groove 20 has a groove width of, for example, 2 mm to 4 mm, and a groove depth of 4 mm to 7 mm. Thereby, the inner middle land portion 14 forms a block row composed of a plurality of blocks.

  In the embodiment illustrated in FIG. 2, the outer intermediate land portion 15 is positioned on the extension line of the first inclined portion 19 </ b> A of the inclined groove 19, one end ends in the outer intermediate land portion 15, and the other end is on the vehicle inner side. A plurality of outer intermediate lug grooves 21 opening in the main groove 11 are formed. The outer intermediate lug groove 21 has a groove width of, for example, 2 mm to 4 mm and a groove depth of 4 mm to 7 mm. Thus, the outer intermediate land portion 15 forms a rib row that continues in the tire circumferential direction.

  In the embodiment illustrated in FIG. 2, the inner shoulder land 17 has a plurality of inner shoulder lug grooves 22 that are not in communication with the main groove 11 adjacent to the inner shoulder land 17 and extend in the tire width direction. A plurality of inner shoulder sipes 23 extending in the tire width direction are formed. The inner shoulder lug groove 22 has a groove width of, for example, 3 mm to 5 mm and a groove depth of 2 mm to 5 mm. The inner shoulder sipe 23 is a fine groove having a groove width of, for example, 0.5 mm to 1.0 mm and a groove depth of 4 mm to 7 mm. The inner shoulder sipe 23 extends in the tire width direction from the end of the inner shoulder lug groove 22 and does not open to the main groove 11 adjacent to the inner shoulder land portion 17 but ends in the inner shoulder land portion 17. 23A and the inner shoulder lug groove 22 are not connected to each other, extend in the tire width direction, have one end terminated in the inner shoulder land portion 17, and the other end opened to the main groove 11 adjacent to the inner shoulder land portion 17. And Sipe 23B. These non-opening sipes 23A and open sipes 23B are alternately arranged in the tire circumferential direction.

  In the present invention, the outer shoulder land 18 is provided with an outer shoulder lug groove 24, an outer shoulder sipe 25, and a circumferential narrow groove 26. One end of the outer shoulder lug groove 24 does not communicate with the main groove 11 adjacent to the outer shoulder land portion 18 and ends in the outer shoulder land portion 18, while the other end does not end in the outer shoulder land portion 18. The outer shoulder land portion 18 is open to the outer side in the tire width direction. The outer shoulder lug groove 24 intersects a circumferential narrow groove 26 described later on one end side, and is divided into a vehicle inner portion 24A and a vehicle outer portion 24B than the circumferential narrow groove 26. The outer shoulder lug groove 24 has a groove width, for example, 3 mm to 5 mm, and a groove depth, for example, 2 mm to 5 mm. The outer shoulder sipe 25 has one end communicating with the main groove 11 adjacent to the outer shoulder land portion 18, and the other end terminating in the outer shoulder land portion 18. The outer shoulder sipe 25 also intersects a circumferential narrow groove 26 described later on one end side, and is divided into a vehicle inner portion 25A and a vehicle outer portion 25B than the circumferential narrow groove 26. The outer shoulder sipe 25 has a groove width of, for example, 0.5 mm to 1.0 mm, and a groove depth of, for example, 4 mm to 7 mm. The circumferential narrow groove 26 is smaller in groove width and depth than the main groove 11 (groove width is, for example, 2 mm to 3 mm, and groove depth is, for example, 4 mm to 6 mm), and from the center in the tire width direction of the outer shoulder land portion 18. Also extends in the tire circumferential direction inside the vehicle and intersects both the outer shoulder lug groove 24 and the outer shoulder sipe 25.

  In each of the outer shoulder lug groove 24 and the outer shoulder sipe 25, the vehicle inner portions 24A and 25A and the vehicle outer portions 24B and 25B are arranged so as to be shifted in the tire circumferential direction. More specifically, as shown in an enlarged view in FIG. 3, the center line of the outer shoulder lug groove 24 at the circumferential narrow groove 26 is the tire circumferential direction between the vehicle inner portion 24 </ b> A and the vehicle outer portion 24 </ b> B. The center line of the outer shoulder sipe 25 is configured to shift in the tire circumferential direction between the vehicle inner portion 25A and the vehicle outer portion 25B. Further, the amount A1 of deviation of the center line of the outer shoulder lug groove 24 is set to 0.5 to 5 times the groove width d1 of the outer shoulder lug groove 24, and the amount of deviation A2 of the center line of the outer shoulder sipe 25 is set to the outer side. The groove width d2 of the shoulder sipe 25 is set to be not less than 0.5 times and not more than 5 times.

  In the present invention, since the outer shoulder land portion 18 has the above-described pattern, the outer shoulder lug groove 24, the outer shoulder sipe 25, and the circumferential narrow groove 26 cooperate particularly in the outer shoulder land portion 18. Thus, dry performance, wet performance, and noise performance can be improved in a well-balanced manner. That is, since the outer shoulder lug groove 24 does not open to the main groove 11, even if air column resonance sound caused by the main groove 11 is generated, it is not transmitted to the outside of the vehicle through the outer shoulder lug groove 24. Noise performance can be increased. Further, since the outer shoulder land portion 18 does not open to the main groove 11 because the outer shoulder lug groove 24 does not open, the rigidity of the outer shoulder land portion 18 is improved, so that the response at the time of steering is improved and the dry performance can be enhanced. On the other hand, since the outer shoulder sipe 25 that opens to the main groove 11 adjacent to the outer shoulder land portion 18 is provided, the outer shoulder lug groove 24 may be lowered by making it not communicated with the main groove 11. The wet performance that is a concern can be complemented. Further, since the circumferential narrow groove 26 intersects both the outer shoulder lug groove 24 and the outer shoulder sipe 25, the circumferential narrow groove 26, the outer shoulder lug groove 24, and the outer shoulder sipe 25 are a series of water passages. Since drainage is promoted, the wet performance can be further improved. In addition to this, the vehicle inner portions 24A and 25A and the vehicle outer portions 24B and 25B of the outer shoulder lug groove 24 and the outer shoulder sipe 25 are arranged so as to be shifted in the tire circumferential direction, so that a groove (sipe) shape is formed. Compared with the case where the is in a straight line, it becomes difficult to transmit sound, and noise performance can be improved. At this time, since the shift amounts A1 and A2 are within a predetermined range, it is possible to prevent the drainage performance from being lowered due to the shift of the groove (sipe), and to improve the noise performance while maintaining the excellent drainage performance. it can.

  At this time, if the deviations A1 and A2 are smaller than 0.5 times the groove widths d1 and d2 of the grooves (sipes), the shape of the grooves (sipes) becomes substantially straight. The effect of shifting 25A from the vehicle outer portions 24B and 25B cannot be obtained. If the deviations A1 and A2 are larger than 5 times the groove widths d1 and d2 of the grooves (sipes), water hardly flows between the vehicle inner portions 24A and 25A and the vehicle outer portions 24B and 25B, and the drainage performance is improved. It deteriorates and the wet performance cannot be improved.

  As shown in FIG. 4, among the corners formed by the outer shoulder lug groove 24 and the circumferential narrow groove 26 in the outer shoulder land portion 18, the angle formed by the outer shoulder lug groove 24 and the circumferential narrow groove 26 is A chamfered portion 27 is provided by chamfering an acute angle portion, and the chamfering amount of the outer chamfered portion 27A located on the outer side of the circumferential narrow groove 26 in the tire width direction is set on the inner side of the circumferential narrow groove 26 on the inner side in the tire width direction. It is preferable to make it larger than the chamfering amount of the chamfered portion 27B. By providing the chamfered portion 27 in this manner, when water flows through the connecting portion between the outer shoulder lug groove 24 and the circumferential narrow groove 26, water easily flows in the groove, and drainage performance can be further improved. . Also, uneven wear at the corners can be suppressed. The chamfering amount is the volume of the portion lost due to chamfering, and is the volume of the triangular pyramid drawn with a dotted line in FIG.

Chamfering of the outer chamfered portion 27A and the inner chamfer 27B need only satisfy the above-mentioned magnitude relation, but preferably sets the chamfering amount of the outer chamfered portion 27A, for example, in the range of 2 mm ³ to 4 mm ^3, the inner For example, the chamfering amount of the chamfered portion 27B may be set in a range of 1 mm ^{3 to} 2 mm ³ . This is advantageous for improving drainage and suppressing uneven wear.

  At this time, it is preferable to set the chamfering depth of the outer chamfered portion 27A and the inner chamfered portion 27B to 80% or more of the groove depth of the circumferential narrow groove 26. By setting the chamfering depth in this way, excellent drainage performance can be maintained until the end of wear. At this time, if the chamfering depth is less than 80% of the groove depth of the circumferential narrow groove 26, the chamfered portion 27 does not remain sufficiently until the end of wear, so that excellent drainage performance can be maintained until the end of wear. Can not. The upper limit value of the chamfering depth of the outer chamfered portion 27A and the inner chamfered portion 27B is 100% of the groove depth of the circumferential narrow groove 26.

  The outer shoulder sipe 25 may have any structure, but preferably has a shape having a bending point. In particular, as illustrated in FIG. 5, it is preferable to have a three-dimensional structure that is a straight line or a curved line having no bending point on the tread surface side and a meandering shape having a bending point on the groove bottom side. As described above, since the outer shoulder sipe 25 has the bent portion, the edge effect by the sipe can be obtained while preventing the rigidity of the outer shoulder land portion 18 from being excessively lowered, so that the drainage performance and the dry performance are well balanced. Can be improved. Also, due to the difference in structure between the tread surface side and the groove bottom side, the zigzag sipe, which is harder to reduce the rigidity than the straight sipe, is more difficult to lower than the straight sipe in the later stage of wear when the rigidity of the land portion is lower than the initial wear. Since it appears on the surface and exhibits its effect, the rigidity of the land portion can be effectively maintained. In FIG. 5, the outer shoulder sipe 24 is indicated by a solid line, while the outer shoulder land portion 18 (a part thereof) is indicated by a one-dot chain line, so that the three-dimensional structure of the outer shoulder sipe 24 becomes clear. An auxiliary line (broken line) is drawn so that the positional relationship between the tread surface side portion of the outer shoulder sipe 24 and the groove bottom side portion (particularly the groove bottom portion) becomes clear.

  It is preferable to chamfer all the edge portions adjacent to the main groove 11 of the circumferential land portion 12 and the shoulder land portion 16. This is advantageous for suppressing uneven wear of the circumferential land portion 12 and the shoulder land portion 16.

  It is preferable to provide a plurality of dimples 29 in the end region 28 on the outer side in the tire width direction of the outer shoulder land portion 18. As a result, it is possible to reduce running resistance and improve fuel efficiency during vehicle running.

  In the embodiment of FIG. 2, the central land portion 13 is configured as described above. In this specification, one end of the inclined groove 19 formed in the central land portion 13 opens into the main groove 11 inside the vehicle. Since the other end terminates in the central land portion 13 at a position on the vehicle inner side than the tire equator CL, the tire noise generated in the vehicle inner region of the tread portion 1 is suppressed from being emitted to the vehicle outer side. be able to. Moreover, the inclined groove 19 formed in the central land portion 13 has the first inclined portion 19A having a relatively large angle with respect to the tire circumferential direction on the opening end side, and the angle with respect to the tire circumferential direction is relatively on the terminal end side. Since it has the small 2nd inclined part 19B, the 2nd inclined part 19B takes in the water of the central land part 13 effectively, and guides the water in the main groove 11 via the 1st inclined part 19A. Can do. Therefore, it is possible to improve the running performance on the wet road surface while suppressing the generation of noise.

  With respect to the embodiment of FIG. 2, as shown in an enlarged view in FIG. 6, the inclination angle α of the first inclined portion 19 </ b> A of the inclined groove 19 with respect to the tire circumferential direction is 45 ° to 90 °, and the second inclined portion of the inclined groove 19. The inclination angle β of 19B with respect to the tire circumferential direction is preferably 0 ° to 30 °. Thereby, the drainage property by the inclined groove 19 can be sufficiently ensured. When these inclination angles α and β are out of the above range, the drainage improvement effect by the inclined groove 19 is lowered. As shown in FIG. 6, the inclined groove 19 has a first inclined portion 19A curved with a predetermined curvature radius r1, and a second inclined portion 19B curved with a predetermined curvature radius r2. 19A and the 2nd inclination part 19B have the shape where the connection part of the predetermined curvature radius tied smoothly. At this time, the center point of the opening end of the inclined groove 19 is P1, the intersection of the center line (curvature radius r1) of the first inclined portion 19A and the center line (curvature radius r2) of the second inclined portion 19B is P2, and the end portion Is the angle formed by the straight line connecting point P1 and point P2 with respect to the circumferential direction, and the inclination angle β is the line connecting P2 and point P3 in the circumferential direction. It is the angle to make. In FIG. 6, the center line of the connecting portion connecting the first inclined portion and the second inclined portion and the radius of curvature thereof are omitted.

  Of the corner portions of the central land portion 13 formed by the first inclined portion 19A of the inclined groove 19 and the main groove 11 opened by the first inclined portion 19A, the angle formed by the first inclined portion 19A and the main groove 11 It is preferable to form a chamfered portion 29 in a portion where is an acute angle. Thereby, while suppressing the uneven wear of the acute angle part formed in the central land part 13 with formation of the inclination groove | channel 19, the drainage property by the inclination groove | channel 19 can be improved.

  As shown in FIG. 7 (cross-sectional view taken along arrow X1-X1 in FIG. 6) and FIG. 8 (cross-sectional view taken along arrow X2-X2 in FIG. 6), the curvature radius R2 is larger than the curvature radius R2 at the end of the inclined groove 19. It is preferable that the radius of curvature R1 at the groove bottom on the opening end side is larger. Although the change in the radius of curvature may be stepwise, it is desirable that the curvature radius gradually increases from the terminal end side toward the opening end side. Further, the groove wall angle θ1 on the opening end side is preferably larger than the groove wall angle θ2 on the terminal end side of the inclined groove 19. Although the change in the groove wall angle may be stepwise, it is desirable that the groove wall angle gradually increase from the terminal end side toward the opening end side. By making the inclined groove 19 into such a shape, the drainage by the inclined groove 19 can be further enhanced. The groove wall angles θ1 and θ2 preferably satisfy the above-described magnitude relationship, but the groove wall angle θ1 is set to 4 ° to 2 °, for example, and the groove wall angle θ2 is set to 1 ° to 2 °, for example. You can also.

  The distance D from the terminal end of the inclined groove 19 to the end of the central land portion 13 outside the vehicle is preferably 20% to 50% of the width W of the central land portion 13 as shown in FIG. Thereby, the drainage by the inclined groove 19 can be ensured while maintaining the rigidity of the central land portion 13. If the distance D is smaller than 20% of the width W of the central land portion 13, the steering stability is lowered due to the rigidity of the central land portion 13 being reduced. Conversely, if the distance D is larger than 50%, the drainage performance becomes insufficient. As shown in FIG. 6, the distance D is the length from the vehicle outermost point at the end of the inclined groove 19 to the vehicle outer end of the central land portion 13.

  In the embodiment illustrated in FIG. 2, the inner intermediate land portion 14 includes a plurality of inner intermediate lugs that are located on an extension line of the inclined portion 19 </ b> A of the inclined groove 19 and penetrate the inner intermediate land portion 14 as described above. Since the groove 20 is provided and the inner intermediate land portion 14 is a block row, the running performance on the wet road surface can be improved based on the inner intermediate lug groove 20.

  The outer intermediate land portion 15 includes a plurality of outer intermediate lug grooves that are located on an extension line of the inclined portion 19A of the inclined groove 19 and terminate in the outer intermediate land portion 15 and open to the main groove 11 inside the vehicle. 21 and the outer intermediate land portion 15 is a rib row. Based on these outer intermediate lug grooves 21, the driving performance on the wet road surface is improved, and the arrangement of the outer intermediate land portion 15 which is a rib row is used. Generation of noise can be suppressed.

  Further, the inner shoulder land portion 17 is provided with a plurality of inner shoulder lug grooves 22 that are not in communication with the main groove 11 adjacent to the inner shoulder land portion 17 and extend in the tire width direction. Based on the shoulder lug groove 22, the running performance on the wet road surface can be improved, and the generation of noise can be suppressed based on the structure in which the inner shoulder land portion 17 is not divided by the inner shoulder lug groove 22. Furthermore, since the plurality of inner shoulder sipes 23 including the non-opening sipes 23A and the open sipes 23B are provided, dry performance, wet performance, and noise performance can be improved in a balanced manner.

  In the present invention, it is sufficient that at least the outer shoulder land portion 18 has the above-described pattern, but land portions other than the outer shoulder land portion 18 (the central land portion 13, the inner intermediate land portion 14, the outer intermediate land portion 15, The inner shoulder land 17) preferably satisfies the embodiment of FIG. 2 as described above.

  In the pneumatic tire, when the tread portion 1 is divided into a vehicle outer region and a vehicle inner region with the tire equator CL as a boundary, the groove area ratio in the vehicle inner region is the groove area ratio in the vehicle outer region. It is preferable that the difference in the groove area ratio is 1% point or more. The upper limit of the difference in groove area ratio is 15% point. Here, the groove area ratio is the ratio (%) of the groove area in the grounding region to the area of the grounding region. The grounding area is the grounding when the air pressure corresponding to the maximum load capacity is filled and the load of 80% of the maximum load capacity is applied in the air pressure-load capacity correspondence table specified in the JATMA Yearbook (2006 edition). This is an area defined by the width TCW. By making the groove area ratio in the area inside the vehicle larger than the groove area ratio in the area outside the vehicle, it is possible to further improve the running performance on the wet road surface while suppressing the generation of noise.

  The tire size is 215 / 60R17 96H, has the cross-sectional shape illustrated in FIG. 1, is based on the tread pattern of FIG. 2, and has a groove width d1 of the outer shoulder lug groove, a vehicle inner portion and a vehicle outer portion. Presence / absence of deviation, deviation A1, ratio A1 / d1, presence / absence of outer chamfered portion and inner chamfered portion, amount of chamfering, ratio of chamfering depth of each chamfered portion to groove depth of circumferential narrow groove, outer shoulder sipe Groove width d2, presence / absence of displacement between the vehicle inner portion and the vehicle outer portion, the displacement amount A2, ratio A2 / d2, its shape, the circumferential land portion, and the edge portion adjacent to the main groove of the shoulder land portion Thirteen types of pneumatic tires of Conventional Example 1, Comparative Examples 1 to 3, and Examples 1 to 9, in which the presence or absence of chamfering and the presence or absence of dimples were set as shown in Table 1, were produced.

  In all of Conventional Example 1, Comparative Examples 1 to 3, and Examples 1 to 9, the groove depth of the circumferential narrow groove is 5.1 mm. In all of Conventional Example 1, Comparative Examples 1 to 3, and Examples 1 to 9, the tread pattern of the portion other than the outer shoulder land portion has the structure shown in FIG. 2, and the inclination angle α of the first inclined portion of the inclined groove is α. Is 50 °, the inclination angle β of the second inclined portion is 20 °, the groove wall angle θ1 on the opening end side of the inclined groove is 4 °, the groove wall angle θ2 on the end side is 2 °, and the central land portion extends from the end of the inclined groove. The distance D to the vehicle outer end is 60% of the width W of the central land portion, and the groove area ratio in the vehicle inner area from the tire equator is larger than the groove area ratio in the vehicle outer area. The difference in the ratio is 2%.

  In the conventional example 1, the outer shoulder lug groove does not intersect with the circumferential narrow groove, and there is no vehicle inner portion, while the vehicle inner portion and the vehicle outer portion of the outer shoulder sipe are greatly displaced, This is an example in which the vehicle inner portion of the outer shoulder sipe is located on the extended line of the outer shoulder lug groove.

  In the column of “shape” of “outer shoulder sipe” in the table, “2D” means a straight sipe, and “3D” means that the tread surface side is straight and the groove bottom side is as shown in FIG. It means a sipe that is zigzag shaped.

  About these 13 types of pneumatic tires, noise performance, dry performance, wet performance, and fuel efficiency performance were evaluated by the following evaluation methods, and the results are also shown in Table 1.

Noise performance Each test tire is mounted on a wheel with a rim size of 17x6.5J, mounted on a test vehicle (front-wheel drive vehicle) with a displacement of 2.4L with air pressure of 230kPa, and EEC / ECE tires that comply with European passing sound regulations The passing sound was measured according to the measurement method based on the single noise regulation. The evaluation results are shown as an index with the conventional example 1 as 100, using the reciprocal of the measured value. The larger the index value, the smaller the passing noise and the better the noise performance.

Dry performance Dry asphalt in which each test tire is assembled to a wheel with a rim size of 17 × 6.5J, mounted on a test vehicle (front-wheel drive vehicle) with a displacement of 2.4 liters with a pneumatic pressure of 230 kPa, and pylons installed at intervals of 35 m The time required for the test driver to run on the slalom on the 175 m slalom test road consisting of the road surface was measured. The evaluation results are shown as an index with the conventional example 1 as 100, using the reciprocal of the measured value. The larger the index value, the shorter the required time and the better the dry performance.

Wet performance Each test tire is mounted on a wheel with a rim size of 17 × 6.5J, mounted on a test vehicle (front-wheel drive vehicle) with a displacement of 2.4 liters with an air pressure of 230 kPa, and pylons installed at 35 m intervals. The time required for the test driver to run on a slalom was measured on a 175 m slalom test road consisting of a 3 mm asphalt road surface. The evaluation results are shown as an index with the conventional example 1 as 100, using the reciprocal of the measured value. The larger the index value, the shorter the required time and the better the wet performance.

Fuel consumption performance Each test tire is mounted on a wheel with a rim size of 17 x 6.5 J, mounted on a test vehicle (front-wheel drive vehicle) with a displacement of 2.4 L with an air pressure of 230 kPa, and traveling for 1 hour at a speed of 100 km / h Fuel consumption (mileage per unit capacity of fuel) was measured. The evaluation results are shown as an index with Conventional Example 1 as 100. A larger index value means better fuel efficiency.

  As is clear from Table 1, Examples 1 to 9 all showed superior noise performance, dry performance, wet performance, and fuel consumption performance compared to Conventional Example 1.

  On the other hand, the noise performance of Comparative Example 1 without the circumferential displacement of the outer shoulder lug groove and the outer shoulder sipe was worse than that of Conventional Example 1. The noise performance of Comparative Example 2 in which the outer shoulder lug groove and the outer shoulder sipe were displaced too little in the circumferential direction was also worse than that of Conventional Example 1. The comparative example 3 in which the amount of shift in the circumferential direction of the outer shoulder lug groove and the outer shoulder sipe was too large was worse in wet performance than in the conventional example 1.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7, 8 Belt layer 9 Belt reinforcement layer 10 Tread surface 11 Main groove 12 Circumferential land part 13 Central land part 14 Inner intermediate land part 15 Outer intermediate part Land portion 16 Shoulder land portion 17 Inner shoulder land portion 18 Outer shoulder land portion 19 Inclined groove 19A First inclined portion 19B Second inclined portion 20 Inner intermediate lug groove 21 Outer intermediate lug groove 22 Inner shoulder lug groove 23 Inner shoulder sipe 24 Outer Shoulder lug groove 24A Vehicle inner portion 24B Vehicle outer portion 25 Outer shoulder sipe 25A Vehicle inner portion 25B Vehicle outer portion 26 Circumferential narrow groove 27 Chamfered portion 27A Outer side chamfered portion 27B Inner side chamfered portion 28 End region 29 Dimple 30 Chamfer CL CL Equator

Claims (15)

The tread surface has at least four main grooves extending in the tire circumferential direction, a plurality of circumferential land portions extending in the tire circumferential direction are defined between adjacent main grooves, and each outermost portion in the tire width direction is defined. In a pneumatic tire in which a shoulder land portion is defined on the outer side in the tire width direction of the main groove, and the mounting direction with respect to the vehicle is specified,
Out of the shoulder land portion, the outer shoulder land portion that is outside of the vehicle when mounted on the vehicle extends in the tire width direction and terminates in the outer shoulder land portion without communicating with the main groove adjacent to the outer shoulder land portion. Outer shoulder lugs and outer shoulder sipes extending in the tire width direction and communicating with the main grooves adjacent to the outer shoulder land portions are alternately provided in the tire circumferential direction, and the groove width and groove depth are larger than the main grooves. A circumferential narrow groove extending in the tire circumferential direction and intersecting the outer shoulder lug groove and the outer shoulder sipes, and a center line of the outer shoulder lug groove and the outer shoulder at the circumferential narrow groove as a boundary The center line of the sipe is shifted in the tire circumferential direction, and the shift amount of the center line of the outer shoulder lug groove is set to 0.5 of the groove width of the outer shoulder lug groove. Or to 5 times or less, pneumatic tire characterized by a shift of the center line of the outer side shoulder sipe was below 5 times 0.5 times the groove width of the outer side shoulder sipe.   Among the corners formed by the outer shoulder lug groove and the circumferential narrow groove in the outer shoulder land portion, chamfering is performed on a portion where the angle formed by the outer shoulder lug groove and the circumferential narrow groove is an acute angle. The chamfering amount of the outer chamfered portion located outside the circumferential narrow groove in the tire width direction is made larger than the chamfering amount of the inner chamfered portion located inside the circumferential narrow groove in the tire width direction. The pneumatic tire according to claim 1.   The pneumatic tire according to claim 2, wherein the chamfering depth of the inner chamfered portion and the outer chamfered portion is 80% or more of the groove depth of the circumferential narrow groove.   4. The outer shoulder sipe has a three-dimensional structure which is a straight line or a curved line having no bending point on the tread surface side and a meandering shape having a bending point on the groove bottom side. The pneumatic tire according to any one of the above.   5. The pneumatic tire according to claim 1, wherein all of edge portions adjacent to the main groove of the circumferential land portion and the shoulder land portion are chamfered.   The pneumatic tire according to any one of claims 1 to 5, wherein a plurality of dimples are provided in an end region on the outer side in the tire width direction of the outer shoulder land portion.   A plurality of inclined grooves extending while inclining with respect to the tire circumferential direction are provided in a central land portion located on the tire equator among the circumferential land portions, and one end of the inclined groove is inward of the vehicle when the vehicle is mounted. The other end of the inclined groove is terminated in the central land portion without being opened in the main groove that is outside the vehicle when the vehicle is mounted, and the tire is disposed on the opening end side of the inclined groove. The first inclined portion having a relatively large angle with respect to the circumferential direction is formed, and the second inclined portion with a relatively small angle with respect to the tire circumferential direction is formed on the terminal side of the inclined groove. The pneumatic tire according to any one of 6.   The inclination angle of the first inclined portion of the inclined groove with respect to the tire circumferential direction is 45 ° to 90 °, and the inclination angle of the second inclined portion of the inclined groove with respect to the tire circumferential direction is 0 ° to 30 °. The pneumatic tire according to claim 7.   Of the corner formed by the first inclined portion of the inclined groove and the main groove opened by the first inclined portion in the central land portion, chamfering is performed on a portion where the inclined angle of the first inclined portion is an acute angle. The pneumatic tire according to claim 7 or 8, wherein the pneumatic tire is applied.   The radius of curvature at the groove bottom of the inclined groove and the groove wall angle with respect to the normal direction of the tread surface are made larger at the opening end side than at the terminal end side of the inclined groove, respectively. The pneumatic tire according to Crab.   The distance from the end of the inclined groove to the end on the outer side with respect to the vehicle when the central land portion is mounted on the vehicle is 20% to 50% of the width of the central land portion. The pneumatic tire according to any one of 7 to 10.   The inner land portion adjacent to the inner side of the circumferential land portion on the inner side with respect to the vehicle when the central land portion is mounted on the extension line of the first inclined portion of the inclined groove, the inner intermediate portion The pneumatic tire according to any one of claims 7 to 11, wherein a plurality of inner intermediate lug grooves penetrating the land portion are provided, and the inner intermediate land portion is formed as a block row including a plurality of blocks. .   Of the circumferential land portion, the outer land portion is located on the extended line of the first inclined portion of the inclined groove on the outer intermediate land portion adjacent to the outer side of the vehicle when the central land portion is mounted on the vehicle. A plurality of outer intermediate lug grooves that terminate in the land portion and open to a main groove that becomes the inner side with respect to the vehicle when the vehicle is mounted are provided, and the outer intermediate land portion is formed as a row of ribs continuous in the tire circumferential direction. The pneumatic tire according to any one of claims 7 to 12.   The inner shoulder land portion that extends in the tire width direction to the inner shoulder land portion that becomes the inner side with respect to the vehicle when the vehicle is mounted, and that does not open to the main groove adjacent to the inner shoulder land portion. A plurality of inner shoulder lug grooves that terminate in the tire, and extend in the tire width direction from the end of the inner shoulder lug groove, and terminate in the inner shoulder land portion without opening to the main groove adjacent to the inner shoulder land portion. A main groove adjacent to the inner shoulder land portion and extending in the tire width direction without being connected to the inner shoulder lug groove between the non-opening sipes adjacent to the tire circumferential direction. An opening sipe that is open with respect to the tire is provided, and the non-opening sipe and the opening sipe are alternately arranged in the tire circumferential direction. The pneumatic tire according to.   When the tread portion is divided into a vehicle outside region that is outside the vehicle when the vehicle is mounted and a vehicle inside region that is inside the vehicle when the vehicle is mounted, the groove area in the vehicle inside region The pneumatic tire according to any one of claims 1 to 14, wherein the ratio is made larger than the groove area ratio in the vehicle outside region, and the difference between the groove area ratios is set to 1% point or more.

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