JP2017001463A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire 11 which can effectively exert abrasion resistance and noise reduction effect.SOLUTION: Bending rigidity in the vicinity a recessed groove 32 of a center block 21 is decreased and rigidity unevenness of a land part 14 as a whole is reduced by dividing the center block 21 into two approximately equal parts with a dividing sipe 37 communicating with the recessed groove 32 and by making a groove depth of the dividing sipe 37 larger than groove depths of the other sipes 33 and 34. Consequently, pitch noise, which is generated when the center block 21 and an outer block 22 ground, is reduced, and heel-and-toe abrasion of the center block 21 and the outer block 22 is reduced so that abrasion resistance is improved.SELECTED DRAWING: Figure 1

Description

    The present invention relates to a pneumatic tire in which a plurality of blocks are formed in a tread portion.

    As conventional pneumatic tires, for example, those described in Patent Document 1 below are known.

JP 2008-044441 A

  This is a pneumatic tire in which a plurality of blocks are defined by providing first to fourth lug grooves in a central land portion row located between a pair of main grooves formed in a tread portion, While the second lug groove is inclined in the same direction with respect to the tire width direction from one end part where the main groove communicates, the second lug groove is joined at the other end part side on the other main groove side, while the third and fourth lug grooves Are inclined in directions opposite to each other with respect to the tire width direction from one end portion communicating with the main groove, and are joined at the other end portion side on the other main groove side.

    And since such a conventional pneumatic tire has a lug groove extending substantially in the tire width direction at the shoulder portion, it can suppress uneven wear at the shoulder portion, and the first to fourth lugs. Since the extension direction of the edge of the block defined by the grooves is multidirectional, it is possible to suppress tire noise by dispersing noise during tire rolling, but in recent years there has been a demand for improved performance for pneumatic tires Therefore, the appearance of pneumatic tires that exhibit further wear resistance and noise reduction effects has been eagerly desired.

  An object of the present invention is to provide a pneumatic tire that can effectively exhibit wear resistance and noise reduction effects.

    The purpose of this is to cross the main groove in the tread portion, a pair of main grooves formed across the tire equator and extending continuously in the circumferential direction, and the land portion located between the main grooves, and the tire equator. Forming a plurality of inclined grooves that are inclined with respect to the inclined grooves and a plurality of intersecting grooves that intersect the inclined grooves, the central blocks that are arranged apart from each other in the circumferential direction and straddle the tire equator, the central blocks, and the pair A plurality of outer blocks separated from each other in the circumferential direction are formed between the main groove and the central block, while the central block and the outer block form sipes that close when contacted with the ground, and the outer blocks are inclined grooves. Are divided into two outer block pieces by a dividing groove extending along the groove, and a concave groove recessed toward the tire equator is formed in the circumferential central portion of the widthwise outer side wall of each central block, and The pneumatic tire larger than the groove depth a groove depth of the other sipe of the sipe which is substantially bisects the central block communicating with the groove, can be achieved.

  In this invention, each outer block is divided by a dividing groove extending along the inclined groove to form two outer block pieces. Therefore, the bending rigidity of these outer block pieces is low, but the central block is along the inclined groove. Since it is not divided, the bending rigidity in the vicinity of the concave portion of the central block is maximized in the land portion. However, since the central block is divided into approximately two equal parts by the dividing sipe communicating with the concave groove, and the groove depth of the divided sipe is made larger than the groove depth of the other sipe, the bending rigidity in the vicinity of the concave portion of the central block. Decreases, and the rigidity step in the entire land portion becomes smaller. Thereby, the pitch noise generated when the block contacts the ground is effectively reduced, and the heel and toe wear of the block is reduced, and the wear resistance is effectively improved.

  In addition, when the split sipe having a deep groove depth as described above is provided in the central block, the amount of collapse of the central block at the time of ground contact increases, but if configured as described in claim 2 of the present application, The split sipe of the part inclined with respect to the direction orthogonal to the falling direction can be stretched to suppress the falling, thereby making it possible to achieve both the reduction in the rigidity step and the suppression of the falling of the central block. Furthermore, if comprised as described in Claim 3, the edge component of a tire width direction will increase, As a result, traction performance will improve effectively. Further, although the rigidity in the vicinity of the circumferential central portion of the circumferential side wall of the outer block piece is high, if configured as described in claim 4, the rigidity of the outer block piece in the vicinity of the circumferential central portion is reduced, As a result, the rigidity can be made more uniform, and pitch noise can be further reduced and wear resistance can be improved. Furthermore, if comprised as described in Claim 5, while being able to aim at coexistence of drainage performance and traction performance, further reduction of pitch noise and improvement of abrasion resistance can be aimed at. Further, although the rigidity in the vicinity of the corner of the central block piece where the side walls intersect at an obtuse angle is high, if configured as described in claim 6, the rigidity of the central block piece in the vicinity of the corner is reduced. Further, the rigidity can be made more uniform to further reduce the pitch noise and improve the wear resistance.

It is a top view of the tread part which shows Embodiment 1 of this invention. It is a top view which shows the land part. It is II sectional view taken on the line of FIG.

Embodiment 1 of the present invention will be described below with reference to the drawings.
1 and 2, reference numeral 11 denotes a pneumatic radial tire that is used by being filled with air, nitrogen gas, or the like. The pneumatic tire 11 has a tread portion 12 that comes in contact with the road during running. The tread pattern formed on the tread surface of the tread portion 12 has a pair of main grooves 13 extending continuously in the tire circumferential direction (hereinafter referred to as the circumferential direction). Never close. The main grooves 13 are formed on both sides of the tire equator S so as to sandwich the tire equator (tread center) S. As a result, a land portion 14 straddling the tire equator S is interposed between the main grooves 13. It is formed. A plurality of inclined grooves 15 inclined at an angle of about 30 degrees with respect to the tire equator S are formed in the land portion 14 located between the main grooves 13, and these inclined grooves 15 are separated by an equal distance in the circumferential direction. Has been placed. Further, these inclined grooves 15 intersect with the main grooves 13 by opening both ends of the tire in the tire width direction (hereinafter referred to as the width direction) to the pair of main grooves 13, respectively. The pair of main grooves 13 and the plurality of inclined grooves 15 define a plurality of land pieces 16 having the same shape and repeatedly arranged in the circumferential direction. The inclination angle of the inclined groove 15 with respect to the tire equator S may be less than the angle described above or may exceed the angle described above.

  20 is a plurality of intersecting grooves that are formed in the land portion 14 (all the land portion pieces 16) and that open at both ends to the adjacent inclined grooves 15 to intersect the inclined grooves 15. These intersecting grooves 20 One land piece 16 is provided on each side of the tire equator S. As a result, each of the land pieces 16 has a central block 21 straddling the tire equator S, the central block 21 and the pair of main grooves 13. And a pair of outer blocks 22 respectively disposed between them. Here, since the land portion pieces 16 are arranged at equal distances in the circumferential direction as described above, a plurality of these central and outer blocks 21, 22 are arranged at equal distances in the circumferential direction as well. become. Each of the crossing grooves 20 described above has a substantially square shape that is bent at the central portion in the longitudinal direction, and the first groove portion 20a on one side extends substantially in the circumferential direction from the bending point, while the second groove portion 20b on the other side is formed in the inclined groove 15. As a result, the opening end of the first groove portion 20a with respect to the inclined groove 15 is closer to the tire equator S than the opening end of the second groove portion 20b with respect to the inclined groove 15. Further, each outer block 22 is formed with a dividing groove 23 extending substantially parallel to the inclined groove 15, and the dividing groove 23 has an outer end in the width direction as the main groove 13 and an inner end in the width direction as the intersecting groove 20, Specifically, the outer block 22 is divided into two outer block pieces 24 and 25 in the circumferential direction by opening in the vicinity of the bending points of the intersecting grooves 20.

  On the other hand, each central block 21 is formed with dividing grooves 28 extending substantially perpendicular to the inclined grooves 15, and both ends of these dividing grooves 28 are opened in the adjacent inclined grooves 15, respectively, so that each central block 21 is approximately 2. Divide into equal parts and divide into a central block piece 29 and a central block piece 30 which have two substantially U-shapes. Here, the center of the dividing groove 28 in the extending direction is located on the tire equator S, and as a result, the central block pieces 29 and 30 are arranged in a state of straddling the tire equator S. Each of the inclined grooves 15 described above includes a central portion 15a extending across the tire equator S between two intersections where the first groove portion 20a and the inclined groove 15 intersect in the central portion of the land portion 14 in the width direction, A pair of outer portions 15b extending from the intersection of the main groove 13 and the inclined groove 15 to the intersection of the dividing groove 28 and the inclined groove 15 at both ends in the width direction of the portion 14 and extending substantially parallel to the central portion 15a; It comprises a pair of intermediate portions 15c that connect both outer ends in the width direction of the central portion 15a and inner ends in the width direction of the pair of outer portions 15b, and extend substantially in the circumferential direction on the extension line of the first groove portion 20a. Yes. As a result, the inclined groove 15 is bent in a zigzag shape in the longitudinal direction.

  A trapezoidal concave groove 32 that is recessed toward the tire equator S is formed in the circumferentially central portion of the width direction outer side wall 21a of each central block 21 described above, and these concave grooves 32 are the same as the intersecting grooves 20 described above. At the depth, it opens to the bent portion of the intersecting groove 20 and is located on the extension line of the dividing groove 23. As a result, the central block pieces 29 and 30 are substantially U-shaped. The central block 21 (central block pieces 29, 30) has a plurality of sipes 33 substantially parallel to the extending direction of the dividing groove 23, and the outer block 22 (outer block pieces 24, 25) has a dividing groove. A plurality of sipes 34 substantially parallel to 28 are formed respectively. These sipes 33 and 34 are either open at both ends to the surrounding groove, or only one end is opened to the surrounding groove, and the remaining one end is a block. Some ends in the middle, or some ends in the middle of the block. Here, the sipes 33 and 34 close at the time of grounding, that is, close in the grounding area, but open when they leave the grounding area, and their width is 3 mm or less. Of the sipe 33, the sipe whose one end communicates with the concave groove 32 has the remaining one end opened to the dividing groove 28, thereby dividing the central block 21 (the central block pieces 29 and 30) into two equal parts. Yes.

  The intersecting groove 20, the dividing groove 33, the outer block pieces 24, 25, the dividing groove 28, and the central block pieces 29, 30 are symmetrical points A on the dividing groove 28, here, the dividing groove 28 and the tire equator S. As a result, the side walls 29a and 30a of the two central block pieces 29 and 30 that are in contact with the dividing groove 28 face each other. Here, as described above, each outer block 22 is divided in the circumferential direction by the dividing groove 23 extending along the inclined groove 15, and thus becomes two outer block pieces 24, 25. Therefore, these outer block pieces 24, 25 are separated. Although the bending rigidity of the central block 21 is low, the central block 21 is divided into the central block pieces 29 and 30 by the dividing groove 28 substantially orthogonal to the inclined groove 15, but the central block 21 is not divided along the inclined groove 15, The bending rigidity of the block 21 (center block pieces 29, 30) in the vicinity of the concave groove 32 is maximum in the land portion 14, and a rigidity step is generated in the entire land portion 14.

  However, in this embodiment, the central block 21 (the central block pieces 29 and 30) is divided into approximately two equal parts by a dividing sipe 37 that communicates with the concave groove 32 and extends along the dividing groove 23. By making the groove depth larger than the groove depths of the other sipes 33, 34, the bending rigidity in the vicinity of the concave groove 32 of the central block 21 is reduced, so the rigidity step in the entire land portion 14 is reduced, As a result, the pitch noise generated when the center and outer blocks 21 and 22 are grounded is effectively reduced, and the heel and toe wear of the center and outer blocks 21 and 22 is reduced and the wear resistance is effectively improved. To do. Here, as described above, when the dividing sipe 37 having a deep groove depth is provided in the central block 21, the rigidity of the central block 21 decreases, and the amount of collapse of the central block 21 at the time of ground contact increases. In this embodiment, since the opening shape in the tread 12 tread surface of the split sipe 37 is bent into a U-shape, the side walls of the split sipe 37 in a portion inclined with respect to the direction orthogonal to the falling direction are in contact with each other. Thus, the falling function is suppressed to suppress the falling, thereby achieving both the reduction in the rigidity step and the central block 21 from falling.

  Here, the side wall on the tire equator S side of the outer block piece 24 described above is in contact with both the first groove portion 20a of the intersecting groove 20 and the intermediate portion 15c of the inclined groove 15 extending in the circumferential direction. A circumferential side wall 24a extending substantially in the circumferential direction is formed along the groove 20a and the intermediate portion 15c. The circumferential side wall 24a protrudes toward the tire equator S and has a triangular columnar projection extending in the radial direction. The strips 40 are formed at approximately equal distances in the circumferential direction. As described above, the outer side block piece 24 is provided with the circumferential side wall 24a extending substantially in the circumferential direction, and the circumferential side wall 24a is formed with a plurality of ridges 40 which are separated in the circumferential direction and extend in the radial direction. If the undulation is made to have a zigzag shape in the circumferential direction, the edge component in the tire width direction is increased, and the traction performance of the pneumatic tire 11 during traveling is effectively improved.

  In this embodiment, as described above, the inclined groove 15, the intersecting groove 20, the dividing groove 23, and the dividing groove 28 are formed in the land portion 14 located between the pair of main grooves 13, but these inclined grooves 15 As shown in FIG. 3, the bottoms of the crossing groove 20, the dividing groove 23, and the dividing groove 28 are raised to form a bottom raised portion 43 that is shallower than the groove depth of the main groove 13. The bottom-up amount at the bottom-up portion 43 of the groove at the portion in contact with the circumferential central portion of the circumferential side wall 24a is smaller than the bottom-up amount at the bottom-up portion 43 of the groove at other portions, for example, by forming a recess Groove depth is increased stepwise or continuously. Thus, the groove (the intermediate portion 15c of the inclined groove 15 and the first groove portion 20a of the intersecting groove 20) in the vicinity of the central portion in the circumferential direction of the outer block piece 24 (circumferential side wall 24a) whose rigidity is increased due to the long circumferential length. ) Is reduced, the rigidity of the outer block piece 24 in the vicinity of the central portion in the circumferential direction decreases. As a result, the rigidity of the entire land portion 14 becomes more uniform, further reducing pitch noise and wear resistance. Can be improved.

  Further, in this embodiment, as described above, the central block 21 is divided into two central block pieces 29 and 30 by the dividing groove 28, and the two central block pieces 29 and 30 are divided into the symmetry points A. Since it is arranged symmetrically with respect to the center, it is possible to achieve both drainage performance and traction performance. Moreover, as described above, the bottom of the split groove 28 that bisects the central block 21 is raised to the bottom. Therefore, it is possible to further reduce pitch noise and improve wear resistance. Further, at the position where the intermediate portion 15c and the dividing groove 28 intersect, the side walls of the central block pieces 29, 30 intersect at an obtuse angle, but the corner portions intersected at an obtuse angle of the central block pieces 29, 30. The vicinity of 29b and 30b has high rigidity. For this reason, in this embodiment, the intermediate portion 15c of the inclined groove 15 in the vicinity of the corner portions 29b and 30b intersecting at an obtuse angle, and the bottom-up amount of the dividing groove 28 are set to other central block pieces 29 whose side walls intersect at an acute angle, Here, when the depth of the groove in the vicinity of the corner of the 30 is smaller than the raised amount of the groove, the depth in the vicinity of the corners 29b and 30b is reduced by increasing the depth of the groove in the same manner as described above. The overall rigidity is made more uniform to further reduce pitch noise and improve wear resistance.

  A plurality of lug grooves 45 extending substantially in the width direction are formed equidistantly in the circumferential direction between the main groove 13 and the pair of tread ends TE on both outer sides in the width direction from the pair of main grooves 13. Thus, a plurality of lugs 46 that are equidistant from each other in the circumferential direction are formed between the main groove 13 and the tread end TE. The lugs 46 are formed with a plurality of sipes 47 that are substantially parallel to the lug grooves 45 and are closed when grounded. In the above-described embodiment, only one pair of main grooves 13 is formed in the tread portion 12. However, in the present invention, at least a pair of main grooves are further formed between the main groove 13 and the tread end TE. It may be. In the present invention, the inclined groove 15 may extend through the pair of main grooves 13 to between the main groove 13 and the tread end TE.

  The present invention can be applied to the industrial field of pneumatic tires in which a plurality of blocks are formed in the tread portion.

11 ... Pneumatic tire 12 ... Tread part
13 ... main groove 14 ... land
15 ... Inclined groove 20 ... Crossing groove
21 ... Central block 22 ... Outer block
23: Dividing groove 24, 25 ... Outer block piece
24a ... circumferential side wall 28 ... dividing groove
29, 30 ... Central block piece 29a, 30a ... Side wall
29b, 30b ... Corner 32 ... Concave groove
33, 34 ... Sipe 37 ... Divided Sipe
40 ... Projection 43 ... Raised part A ... Symmetry point S ... Tire equator

Claims (6)

    A pair of main grooves formed in the tread portion across the tire equator and extending continuously in the circumferential direction, and a land portion located between the main grooves, intersecting the main groove and being inclined with respect to the tire equator And a plurality of intersecting grooves intersecting the inclined grooves, the plurality of center blocks that are arranged apart from each other in the circumferential direction and straddle the tire equator, and between the center block and the pair of main grooves A plurality of outer blocks separated from each other in the circumferential direction are formed, while a sipe that closes at the time of grounding is formed in the central block and the outer block, and each outer block extends along an inclined groove. The outer block is divided into two outer block pieces, and a concave groove recessed toward the tire equator is formed in the circumferential central portion of the widthwise outer side wall of each central block. Further, the central block communicates with the concave groove. A pneumatic tire, wherein a groove depth of the sipe that a click nearly bisected was larger than the groove depth of the other sipe.     The pneumatic tire according to claim 1, wherein an opening shape in a tread portion tread surface of the divided sipe is bent.     The pneumatic tire according to claim 1 or 2, wherein a circumferential side wall extending substantially in the circumferential direction is provided on the outer block piece, and a plurality of ridges extending in the circumferential direction and extending in the radial direction are formed on the circumferential side wall.     While raising the bottom of the inclined groove, the crossing groove and the dividing groove formed in the land portion located between the pair of main grooves to form a bottom raised portion shallower than the groove depth of the main groove, The pneumatic tire according to claim 3, wherein a bottom-up amount at a bottom-up portion of a portion in contact with the center in the direction is smaller than a bottom-up amount of a bottom-up portion at another portion.     The central block is divided into two central block pieces by a dividing groove substantially orthogonal to the inclined groove, while these two central block pieces are arranged symmetrically with respect to the symmetry point on the dividing groove, The pneumatic tire according to claim 4, wherein the side walls of the two central block pieces in contact with the dividing groove are opposed to each other, and the groove bottom of the dividing groove is also raised to form a bottom raised portion.     The pneumatic tire according to claim 5, wherein a bottom raising amount of the groove in the vicinity of the corner portion of the central block piece where the side walls intersect with each other at an obtuse angle is smaller than a bottom raising amount of the groove at the corner portion of the other central block piece.

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