JP2017071282A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which improves driving performance while securing drainage performance.SOLUTION: Groove widths GWb and GWc of central main grooves 3B and 3C are wider than groove widths GWa and GWd of an inside main groove 3A and an outside main groove 3D. A plurality of lateral grooves 4A that define an inside shoulder block 6 belonging to an inside shoulder column 5A are provided in a tire circumferential direction with intervals. In the lateral grooves 4A, every other first bulking portion 16 that connects a pair of the inside shoulder blocks 6 is provided on the side of the inside main groove 3A. A depth GD1' of the lateral groove 4A in the first bulking portion 16 is shallower than a depth GD1 in other portion of the lateral groove 4A. In the outside main groove 3D, a second bulking portion 17 is provided in a region defined by a virtual line connecting an outside intermediate block 9 and an outside shoulder block 10. A depth GWO' of the outside main groove 3D in the second bulking portion 17 is shallower than a depth GWO in the other portion of the outside main groove 3D.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire.

  The pneumatic tire disclosed in Patent Literatures 1 to 4 includes a plurality of block rows extending in the tire circumferential direction. Each block row has a plurality of blocks arranged in the tire circumferential direction. However, in these conventional pneumatic tires, it is not always realized to improve all of driving performance, braking performance, and turning performance while ensuring drainage performance.

International Publication No. 2012/111589 Japanese Patent No. 5639461 Japanese Patent No. 3376342 JP 2012-96782 A

  An object of the present invention is to improve driving performance, braking performance, and turning performance while ensuring drainage performance in a pneumatic tire.

  The present invention includes four main grooves formed in the tread portion so as to extend in the tire circumferential direction, a plurality of lateral grooves formed in the tread portion, the main grooves, and a pair of the lateral grooves adjacent to each other in the tire circumferential direction. And five block rows each having a plurality of blocks arranged in the tire circumferential direction, each of which is defined by the above, and the mounting posture in the tire width direction with respect to the vehicle body and the rotation direction when the vehicle moves forward are designated The main groove is an inner main groove located on the innermost side in the tire width direction when mounted on the vehicle, an outer main groove located on the outermost side in the tire width direction when mounted on the vehicle, and the inner main groove. A first central main groove adjacent to the outer side in the tire width direction of the groove and a second central main groove adjacent to the inner side in the tire width direction of the outer main groove, wherein the block row includes the tire width direction of the inner main groove Inside located inside A shoulder row, an outer shoulder row located on the outer side in the tire width direction of the outer main groove, an inner intermediate row located between the inner main groove and the first central main groove, the outer main groove and the first An outer intermediate row positioned between two central main grooves, and a central row positioned between the first central main groove and the second central main groove, the first central main groove and the second The groove width with the central main groove is wider than the groove width between the inner main groove and the outer main groove, and the lateral grooves are spaced apart in the tire circumferential direction so as to define the blocks belonging to the inner shoulder row. A plurality of first lateral grooves provided in an open manner are provided, and the first lateral grooves are provided with a first raised portion for connecting a pair of blocks belonging to the inner shoulder row on the inner main groove side. And the depth of the first lateral groove in the first raised portion is the first lateral The second raised portion is formed in a region defined by a virtual line connecting the block belonging to the outer intermediate row and the block belonging to the outer shoulder row to the outer main groove, which is shallower than the depth of the other portion. Is provided, and the depth of the outer main groove in the second raised portion is shallower than the depth of the other part of the outer main groove.

  The first central main groove and the second central main groove are located in the center of the tread portion in the tire width direction. At the center of the tread portion in the tire width direction, the boundary portion of the contact area with the road surface extends in the tire width direction (lateral direction) on both the stepping side and the kicking side. Therefore, the water that enters the contact area at the center of the tread portion in the tire width direction has a velocity vector that faces the tire circumferential direction. Therefore, by setting the groove widths of the first central main groove and the second central main groove at the center in the tire width direction to be wide, water entering the ground contact area can be efficiently transferred to the first central main groove and the second central main groove. It can guide and drain effectively. That is, drainage performance can be improved by setting the groove widths of the first central main groove and the second central main groove wide.

  A first lateral groove is provided between the blocks constituting the inner shoulder row. The first lateral grooves allow deformation of these blocks in the tire width direction and reduce the rigidity in the front-rear direction (tire circumferential direction). However, by providing the first raised portion for connecting the pair of blocks belonging to the inner shoulder row in the first lateral groove, these blocks can be integrally deformed with respect to the load in the front-rear direction. That is, by providing the first raised portion, the rigidity in the front-rear direction of the blocks constituting the inner shoulder row can be increased, and the driving performance and braking performance on the dry road surface can be improved.

  A camber angle is given to a pneumatic tire (hereinafter referred to as a tire) mounted on a vehicle. Therefore, on the dry road surface, the shape of the contact area to the road surface tends to extend in the tire circumferential direction at the inner portion of the tread portion in the tire width direction (particularly during braking). Therefore, the driving performance and the braking performance on the dry road surface can be improved more effectively by connecting the blocks constituting the inner shoulder row with the first raised portion to increase the rigidity.

  The 1st raising part is provided in the some 1st horizontal groove every other piece. Therefore, in the 1st horizontal groove in which the 1st raising part is not provided, the flow of water is not prevented by the 1st raising part, but ensuring of drainage performance is given priority. That is, by providing the first raised portions every other one in the plurality of first lateral grooves, it is possible to achieve both of ensuring drainage performance and improving driving performance and braking performance on the dry road surface.

  One side in the tire width direction of the block belonging to the outer intermediate row is defined by the outer main groove. Further, both sides in the tire circumferential direction of the blocks belonging to the outer intermediate row are defined by lateral grooves. These outer main grooves and lateral grooves allow deformation of the blocks belonging to the outer intermediate row in the tire width direction and reduce the rigidity in the lateral direction (tire width direction). However, by connecting the blocks belonging to the outer intermediate row and the blocks belonging to the outer shoulder row by the second raised portion, these blocks can be integrally deformed with respect to the lateral load. That is, by providing the second raised portion, the lateral rigidity of the blocks belonging to the outer intermediate row can be increased, and the steering performance or turning performance on the dry road surface can be improved.

  The second raised portion is not provided in the entire outer main groove, but is partially provided in a region defined by an imaginary line connecting the block belonging to the outer intermediate row and the block belonging to the outer shoulder row. ing. For this reason, the influence of the second raised portion on the flow of water in the outer main groove is limited, and the drainage performance is ensured.

  It is preferable that the depth of the first lateral groove in the first raised portion is set to be not less than 0.4 times and not more than 0.6 times the depth of other portions of the first lateral groove.

  When the depth of the first lateral groove in the first raised portion exceeds 0.6 times the depth in the other portion, the longitudinal rigidity by connecting the pair of blocks belonging to the inner shoulder row with the first raised portion The improvement effect cannot be obtained sufficiently. On the other hand, if the depth of the 1st horizontal groove in a 1st raising part is less than 0.4 times the depth in another part, the drainage function of a 1st horizontal groove will be impaired remarkably.

  It is preferable that the depth of the outer main groove in the second raised portion is set to be not less than 0.5 times and not more than 0.7 times the depth of other portions of the outer main groove.

  When the depth of the outer main groove in the second raised portion exceeds 0.7 times the depth in the other portion, the block belonging to the outer intermediate row is connected to the block belonging to the outer shoulder row at the second raised portion. The effect of improving the rigidity in the lateral direction due to cannot be sufficiently obtained. On the other hand, when the depth of the outer main groove in the second raised portion is less than 0.5 times the depth in other portions, the drainage function of the outer main groove is significantly impaired.

  The lateral groove includes a plurality of second lateral grooves provided at intervals in the tire width direction so as to define the blocks belonging to the outer shoulder row, and the second lateral groove is in the tire width direction of the tread portion. It is preferable to extend in the tire width direction so as to exceed the outer ground contact end.

  In the region from the outer middle row to the outer shoulder row, i.e., the region from the outer middle to the outer side in the tire width direction of the tread portion, the water entering the contact area to the road surface is outside in the tire width direction with respect to the tire circumferential direction Has a velocity vector inclined to Further, the inclination angle increases toward the outer side in the tire width direction of the tread portion. Therefore, the drainage can be effectively performed by providing the second lateral groove that defines the block of the outer shoulder row so as to extend beyond the ground contact end on the outer side in the tire width direction.

  The lateral groove includes a plurality of third lateral grooves provided at intervals in a tire width direction so as to define the blocks belonging to the outer intermediate row, and the second lateral groove and the third lateral groove are It is preferable that they are arranged in a state of being aligned so as to communicate from the two central main grooves to the ground contact end on the outer side in the tire width direction.

  At the time of turning, the area of the contact area to the road surface increases in a region including the outer shoulder row, that is, a region outside the tread portion in the tire width direction. Therefore, in order to improve drainage performance during turning, it is necessary to promote the flow of water in the second lateral groove toward the outside in the tire width direction. By aligning the third lateral groove defining the block of the outer intermediate row with respect to the second lateral groove so as to communicate from the second central main groove to the grounding end, the flow of water in the second lateral groove during turning Can be effectively drained.

  The blocks belonging to the inner shoulder row are preferably provided with a plurality of first slits arranged in a staggered pattern in the circumferential direction.

  Due to the influence of the camber angle, the shape of the contact area to the road surface tends to extend in the tire circumferential direction at the inner portion in the tire width direction of the tread portion, that is, the portion where the inner shoulder row is provided (particularly during braking). By providing the first slits arranged in a staggered manner in the blocks belonging to the inner shoulder row, it is possible to disperse the deformation and the ground pressure in the blocks belonging to the inner shoulder row during braking. As a result, the braking performance on the dry road surface can be improved.

  The blocks belonging to the outer shoulder row are preferably provided with a plurality of second slits communicating in the circumferential direction.

  The blocks belonging to the outer middle row and the blocks belonging to the outer shoulder row are connected by the second raised portion. Therefore, when a block belonging to the outer intermediate row is deformed with respect to a lateral load during turning, a lateral load (deformation in the tire width direction) is applied from the block belonging to the outer intermediate row to the block belonging to the outer shoulder row. It is transmitted. By providing the second slit, the lateral load (deformation in the tire width direction) transmitted from the block belonging to the outer intermediate row to the block belonging to the outer shoulder row during turning can be reduced. As a result, turning performance on a dry road surface can be improved.

  In the pneumatic tire according to the present invention, driving performance, braking performance, and turning performance can be improved while ensuring drainage performance.

The expanded view of the tread pattern of the tire which concerns on embodiment of this invention. The elements on larger scale of FIG. The schematic cross section for demonstrating various grooves. FIG. 4 is a schematic cross-sectional view taken along line IV-IV in FIG. 2. The schematic cross section in the VV line of FIG.

  Embodiments of the present invention will be described with reference to the accompanying drawings.

  Referring to FIGS. 1 and 2, the tread portion 2 of a pneumatic tire 1 (hereinafter referred to as a tire) which is a rubber snow tire according to the embodiment has a tire circumferential direction (reference numeral Y in FIGS. 1 and 2). 4 main grooves 3 </ b> A to 3 </ b> D formed so as to extend. Further, the tread portion 2 is provided with a plurality of lateral grooves (lug grooves) 4A to 4F formed so as to extend in the tire width direction (indicated by the symbol X in FIGS. 1 and 2).

  The tire 1 is designated to be attached to the vehicle (not shown) in the tire width direction. Further, the rotation direction of the tire 1 when the vehicle moves forward is designated in the direction indicated by the arrow A in FIG. In the following description, the terms “inside” and “outside” in the tire width direction are based on the case where the tire 1 is mounted on the vehicle in a normal posture. 1 and 2, the center line (equatorial line) of the tread portion 2 in the tire width direction is indicated by reference sign CL. Further, the inner and outer grounding ends of the tread portion 2 in the tire width direction are denoted by reference signs GEi and GEo, respectively.

  Referring also to FIG. 3, the inner main groove 3A located on the innermost side in the tire width direction is a linear groove having a groove depth GD0 and a substantially constant groove width GWa. The outer main groove 3D located on the outermost side in the tire width direction is a groove having a groove depth GD0 and a zigzag groove width GWd that is slightly meandering. The first central main groove 3B adjacent to the outer side in the tire width direction of the inner main groove 3A is a linear groove having a groove depth GD0 and a substantially constant groove width GWb. The second central main groove 3C adjacent to the inner side in the tire width direction of the outer main groove 3D and adjacent to the outer side in the tire width direction of the first central main groove 3B has a groove depth GD0, and the groove width GWc is substantially constant. This is a linear groove.

  Five block rows extending in the tire circumferential direction by the four main grooves 3A to 3D and the lateral grooves 4A to 4E, that is, the inner shoulder row 5A, the inner intermediate row 5B, the central row 5C, the outer intermediate row 5D, and the outer shoulder Row 5E is formed.

  The inner shoulder row 5A located on the innermost side in the tire width direction in the block row is located on the inner side in the tire width direction of the inner main groove 3A. The inner shoulder row 5A extends beyond the inner ground contact edge GEi to the inner side in the tire width direction (side portion side of the tire 1 not shown). The inner shoulder row 5A has a plurality of inner shoulder blocks 6 defined by the inner main groove 3A and a plurality of lateral grooves 4A (first lateral grooves) provided at intervals in the tire circumferential direction. In other words, the inner shoulder row 5A is composed of a plurality of inner shoulder blocks 6 arranged in the tire circumferential direction. Each inner shoulder block 6 is formed with two sipes 6a extending in the tire width direction. A zigzag slit 6b extending in the tire circumferential direction is provided at the outermost portion in the tire width direction of each inner shoulder block 6A. Further, each inner shoulder block 6A is provided with three inner longitudinal slits (first slits) 6c, 6d, 6e, as will be described in detail later.

  Outer shoulder row 5E located on the outermost side in the tire width direction in the block row is located on the outer side in the tire width direction of outer main groove 3D. The outer shoulder row 5E extends beyond the outer ground contact edge GEo to the outer side in the tire width direction (side portion side of the tire 1 not shown). The outer shoulder row 5E has a plurality of outer shoulder blocks 10 defined by the outer main groove 3D and a plurality of lateral grooves 4F (second lateral grooves) provided at intervals in the tire circumferential direction. In other words, the outer shoulder row 5E is composed of a plurality of outer shoulder blocks 10 arranged in the tire circumferential direction. Each outer shoulder block 10 is formed with three sipes 10a extending in the tire width direction. Each outer shoulder block 10 is provided with one outer longitudinal slit (second slit) 10b as will be described in detail later. A pair of lateral grooves 4 adjacent to each other in the tire circumferential direction are connected by short vertical grooves 11 in a region further outside than the outer grounding end GEo.

  The inner middle row 5B is adjacent to the inner shoulder row 5A on the outer side in the tire width direction, and is located between the inner main groove 3A and the first central main groove 3B. The inner intermediate row 5B includes a plurality of inner intermediate blocks 7 defined by the inner main groove 3A, the first central main groove 3B, and a plurality of lateral grooves 4B provided at intervals in the tire circumferential direction. In other words, the inner intermediate row 5B is configured by a plurality of inner intermediate blocks 7 arranged in the tire circumferential direction. Each inner intermediate block 7 is provided with a lateral slit 7a penetrating in the tire width direction near the center in the tire circumferential direction. The inner intermediate block 7 is formed with two sipes 7b extending in the tire width direction on both sides of the lateral slit 7a.

  The outer intermediate row 5D is adjacent to the outer shoulder row 5E on the inner side in the tire width direction, and is located between the outer main groove 3D and the second central main groove 3C. The outer intermediate row 5 is defined by an outer main groove 3D, a second central main groove 3C, and a plurality of lateral grooves (third lateral grooves) 4D and 4E that are alternately provided at intervals in the tire circumferential direction. Outer intermediate block 9. In other words, the outer intermediate row 5D is composed of a plurality of outer intermediate blocks 9 arranged in the tire circumferential direction. Each of the outer intermediate blocks 9 is formed with three sipes 9a extending in the tire width direction.

  The center row 5C is provided on the center line CL. The central row 5C is adjacent to the inner intermediate row 5B and the outer intermediate row 5D, and is located between the first central main groove 3B and the second central main groove 3C. The center row 5C has a plurality of center blocks 8 defined by a first center main groove 3B, a second center main groove 3C, and a plurality of lateral grooves 4C provided at intervals in the tire circumferential direction. In other words, the central row is constituted by a plurality of central blocks 8 arranged in the tire circumferential direction. Each center block 8 is formed with a plurality of sipes 8a extending in the tire width direction.

  The lateral grooves 4A to 4F will be described with reference to FIG. The lateral grooves 4A of the inner shoulder row 5A, the lateral grooves 4D of the outer intermediate row 5D, and the lateral grooves 4F of the outer shoulder row 5E are “deep lateral grooves”. On the other hand, the lateral grooves 4B in the inner intermediate row 5B, the lateral grooves 4C in the central row 5C, and the lateral grooves 4E in the outer intermediate row 5D are “shallow grooves with sipes”.

  The lateral grooves 4A, 4D and 4F which are “deep lateral grooves” have a substantially rectangular cross-sectional shape. The groove depth GD1 of these lateral grooves 4A, 4D, 4F is set to be 0.85 times or more and 1.0 times or less of the groove depth D0 of the main grooves 3A to 3D (0.85GD0 ≦ GD1 ≦ 1. 0GD0). Further, the groove width GW1 of these lateral grooves 4A, 4D, 4F is preferably 2.5 mm or more and 8 mm or less.

  The lateral grooves 4 </ b> B, 4 </ b> C, and 4 </ b> E that are “shallow grooves with sipes” have a shape in which sipes 14 are provided at the groove bottoms of the shallow grooves 13. In this specification, a groove having a groove depth GD2 that is 0.4 to 0.6 times the groove depth GD0 of the main grooves 3A to 3D is referred to as a “shallow groove” (0.4GD0 ≦ GD2 ≦ 0. 6GD0). The groove width GW2 of the “shallow groove” is preferably equal to or less than the groove width GW1 of the “deep lateral groove” (GW2 ≦ GW1). Further, in this specification, “sipe” means a cut that is narrower than “main groove”, “deep lateral groove”, and “shallow groove”, and generally the width GW3 is 0.8 mm or more and 1.5 mm. It is as follows. The groove depth GD3 of the “shallow groove with sipe” is preferably 0.6 to 1.0 times the groove depth GD0 of the main grooves 3A to 3D (0.6GD3 ≦ GD0 ≦ GD0). The concept of “sipe” includes the sipe 6a of the inner shoulder block 6, the sipe 10a of the outer shoulder block 10, the sipe 7b of the inner intermediate block 7, the sipe 9a of the outer intermediate block 9, and the sipe 8a of the central block 8. Yes.

  In general, the “shallow groove with sipe” is more resistant to falling due to a reaction force from the ground than a groove having the same total depth. Accordingly, it is possible to prevent a decrease in rigidity while preventing a decrease in snow column shear force. In order to obtain the effect of improving the snow performance by adding the sipe 14 to the groove bottom of the shallow groove 13, the depth of the sipe 14 itself is preferably at least 0.2 mm. Moreover, if the width GW3 of the “sipe” is smaller than 0.8 mm, the effect of improving the snow performance is small, and conversely, if the width GW3 exceeds 1.5 mm, the rigidity reduction of the tread portion is increased. Absent.

  As described above, the inner shoulder block 6 is provided with the zigzag slit 6b. The inner shoulder block 6 is provided with inner vertical slits 6c, 6d, 6e. Further, the outer shoulder block 10 is provided with an outer vertical slit 10b. Furthermore, the inner intermediate block 7 is provided with a lateral slit 7a. In the present specification, these “slits” have depths and widths larger than “sipes”, but have depths and grooves smaller than those of “main grooves”, “deep lateral grooves”, and “shallow grooves”. say.

  Referring to FIG. 2, the inner intermediate block 7 constituting the inner intermediate row 5B has a tire circumferential direction length IHc longer than a tire width direction length IHw. That is, the inner intermediate block 7 has an elongated shape in the tire circumferential direction. For example, the tire circumferential direction length IHc is preferably set to 1.3 times or more and 1.9 times or less (1.3 ≦ IHc / IHw ≦ 1.9) of the tire width direction length IHw. A camber angle is given to the tire 1 mounted on the vehicle. The shape of the contact area to the road surface tends to extend in the tire circumferential direction at the inner portion in the tire width direction of the tread portion 2 (particularly during braking). Therefore, when the inner intermediate block 7 has a shape elongated in the tire circumferential direction, driving performance and braking performance on a dry road surface are improved. Further, since the inner intermediate block 7 has an elongated shape in the tire circumferential direction, the responsiveness to the rudder angle when steered while traveling is improved.

  Referring to FIG. 2, the outer intermediate block 9 constituting the outer intermediate row 5D has a tire width direction length OHw longer than a tire circumferential direction length OHc. That is, the outer intermediate block 9 has an elongated shape in the tire width direction. For example, the tire width direction length OHw is preferably set to 1.1 times or more and 1.5 times or less of the tire circumferential direction length OHc (1.1 ≦ OHw / OHc ≦ 1.5). The rigidity with respect to the load in the lateral direction (tire width direction) of the outer intermediate block 9 is increased, and the turning performance on the dry road surface is improved. Further, since the outer intermediate block 9 has an elongated shape in the tire width direction, an edge component in the tire width direction increases in a region outside the tread portion 2 in the tire width direction. As a result, driving performance and braking performance on a snow road are also improved.

  In the present embodiment, the total number Na of the inner shoulder blocks 6 is set to be greater than the total number Ne of the outer shoulder blocks 10 (Na> Ne). The total number Nb of the inner intermediate blocks 7 is set to be smaller than the total number Nd of the outer intermediate blocks 9 (Nb <Nd). In the present embodiment, the total number Nd of the outer intermediate blocks 9 and the total number Ne of the outer shoulder blocks 10 are set to be equal (Nd = Ne). In short, in the present embodiment, the total number of blocks Na, Nb, Nd, Ne satisfies the relationship shown below.

  Further, the total number Nc of the central blocks 8 is set to be smaller than the total number Na, Nb, Nd, Ne of the blocks in the block columns other than the central column C.

  The total number Na of the inner shoulder blocks 6 can be set to 1.8 to 2.5 times the total number Nb of the inner intermediate blocks 7. Further, the total number Nc of the central blocks 8 can be set to 1.0 to 1.4 times the total number Nb of the inner intermediate blocks 7. Further, the total number Nd of the outer intermediate blocks 9 can be set to 1.3 times or more and 1.7 times or less of the total number Nb of the inner intermediate blocks 7. Furthermore, the total number Ne of the outer shoulder blocks 10 can be set to be 1.3 times to 1.7 times the total number Nb of the inner intermediate blocks 7.

  By setting the total number Na of the inner shoulder blocks 6 to be larger than the total number Ne of the outer shoulder blocks 10, the traction due to the snow column shear force is increased particularly at the inner portion in the tire width direction of the tread portion 2 and the snow performance is improved. . Setting the total number Na of the inner shoulder blocks 6 to be larger than the total number Ne of the outer shoulder blocks 10 means that the outer shoulder block 10 is relatively larger than the inner shoulder block 6. Therefore, the rigidity with respect to the lateral load of the outer shoulder block 10 is relatively high with respect to the inner shoulder block 6, and the turning performance on the dry road surface is improved.

  By setting the total number Nb of the inner intermediate blocks 7 to be smaller than the total number Nd of the outer intermediate blocks 9, as described above, the tire circumferential length IHc of the inner intermediate block 7 is the tire circumferential length of the outer intermediate block 7. It is set relatively longer than OHc. As a result, as described above, the driving performance and braking performance on the dry road surface are improved, and the response to the steering angle is also improved.

  Referring to FIG. 2, the tire circumferential length CHc of the central block 8 is the tire circumferential lengths ISHc, IHc, OHc, and the inner shoulder block 6, the inner intermediate block 7, the outer intermediate block 9, and the outer shoulder block 10. It is set longer than any of OSHc. Since the center row 5C includes the center portion in the tire width direction of the contact area with the road surface, the responsiveness to the steering angle is further improved by setting the tire circumferential direction length IHc of the center block 8 to be long.

  From the above characteristics, in the tire according to the present embodiment, the driving performance and the braking performance can be improved, and the turning performance can be improved.

  The inner intermediate block 7 constituting the inner intermediate row 5B is defined by the lateral grooves 4 which are “shallow grooves with sipes”. In this respect, it can be said that the inner intermediate row 5B is not a block row but a substantially rib row. As described above, due to the camber angle, the shape of the contact area to the road surface tends to extend in the tire circumferential direction at the inner portion in the tire width direction of the tread portion 2 (particularly during braking). Therefore, by making the inner intermediate row 5B substantially a rib row, the braking performance on the dry road surface is improved and the responsiveness to the steering angle is improved.

  The outer intermediate block 9 constituting the outer intermediate row 5D is defined by alternately providing the lateral grooves 4D which are “deep lateral grooves” and the lateral grooves 4E which are “shallow grooves with sipes”. As described above, the outer intermediate block 9 has the tire width direction length OHw longer than the tire circumferential direction length OHc. In other words, the outer intermediate row 5D has a large size in the tire width direction. By providing the lateral grooves 4D which are “deep lateral grooves” in the outer intermediate row 5D having a large dimension in the tire width direction, the traction on the snow road surface can be increased, and the driving performance and the braking performance on the snow road surface can be improved. The pair of outer intermediate blocks 9 arranged on both sides in the tire circumferential direction of the lateral groove 4E that is the “shallow groove with sipes” can be regarded as one large block. Therefore, the rigidity in the front-rear direction (tire circumferential direction) of the outer intermediate row 5D is improved, and the maneuverability is improved.

  Hereinafter, various other characteristics of the tire 1 of the present embodiment will be described.

  1 and 2, the groove width GWb of the first central main groove 3B and the groove width GWc of the second central main groove 3C are greater than the groove width GWa of the inner main groove 3A and the groove width GWd of the outer main groove 3D. Is also widely set.

  The first central main groove 3B and the second central main groove 3C are located in the center of the tread portion 2 in the tire width direction. At the center of the tread portion 2 in the tire width direction, the boundary portion of the contact area with the road surface extends in the tire width direction (lateral direction) on both the stepping side and the kicking side. Therefore, the water that enters the contact area at the center of the tread portion 2 in the tire width direction has a velocity vector that faces the tire circumferential direction. Therefore, by setting the groove widths GWb and GWc of the first central main groove 3B and the second central main groove 3C at the center in the tire width direction to be wide, water entering the ground contact area can be efficiently passed through the first central main groove 3B. It can guide to the 2nd center main groove 3C, and can drain effectively. That is, drainage performance can be improved by setting the groove widths GWb and GWc of the first central main groove 3B and the second central main groove 3C to be wide.

  Referring to FIGS. 1 and 2, the plurality of lateral grooves 4A provided in the outer shoulder row 5EA are provided with first raised portions 16 every other one. The first raised portion 16 is provided on the inner main groove 3A side of the lateral groove 4A so as to connect a pair of outer shoulder blocks 10A located adjacent to both sides of the lateral groove 4A in the tire circumferential direction. The length of the first raised portion 16 in the tire width direction is set to be sufficiently shorter than the length of the lateral grooves 4A in the tire width direction. Referring also to FIG. 4, the top surface of the first raised portion 16 is generally flat. Further, the groove depth GD1 ′ of the lateral groove 4A in the first raised portion 16 is set to be shallower than the groove depth GD1 of the transverse groove 4A in the portion other than the first raised portion 16 (which is a “deep transverse groove” as described above). Has been.

  Due to the influence of the camber angle, on the dry road surface, the shape of the contact area to the road surface tends to extend in the tire circumferential direction at the inner portion in the tire width direction of the tread portion 2 (particularly during braking). Therefore, the driving performance and the braking performance on the dry road surface can be improved by connecting the inner shoulder blocks 6 constituting the inner shoulder row 5A with the first raised portion 16 to increase the longitudinal and lateral rigidity.

  Every other first raised portion 16 is provided in each of the plurality of lateral grooves 4A. Therefore, in the lateral groove 4A where the first raised portion 16 is not provided, the flow of water is not hindered by the first raised portion 16, and priority is given to ensuring drainage performance. That is, by providing every other first raised portion 16 in each of the plurality of lateral grooves 4A, it is possible to achieve both of ensuring drainage performance and improving driving performance and braking performance on the dry road surface.

  The groove depth GD1 'of the lateral groove 4A in the first raised portion 16 is preferably set to be not less than 0.4 times and not more than 0.6 times the groove depth GD1 of the other part of the lateral groove 4A. When the groove depth GD1 ′ exceeds 0.6 times the groove depth GD1, the height of the first raised portion 16 is insufficient, and the rigidity in the front-rear direction by connecting the inner shoulder block 6 with the first raised portion 16 is increased. The improvement effect cannot be obtained sufficiently. On the other hand, when the groove depth GD1 'is less than 0.4 times the groove depth GD1, the groove depth of the lateral groove 4A is insufficient, and the drainage function of the lateral groove 4A is significantly impaired.

  Referring to FIGS. 1 and 2, the outer main groove 3D has a region defined by a virtual line connecting the outer intermediate block 9 constituting the outer intermediate row 5D and the outer shoulder block 10 constituting the outer shoulder row 5E. The 2nd raising part 17 is provided in this. The second raised portion 17 connects the side surface on the outer side in the tire width direction of the outer intermediate block 9 and the side surface on the inner side in the tire width direction of the outer shoulder block 10. Referring also to FIG. 5, the end surface of the second raised portion 17 is generally flat. Further, the groove depth GW0 ′ of the outer main groove 3D in the second raised portion 17 is set to be shallower than the groove depth GW0 of the outer main groove 3D in the portion other than the second raised portion 17.

  One side in the tire width direction of the outer intermediate block 9 constituting the outer intermediate row 5D is defined by the outer main groove 3D. Further, both sides in the tire circumferential direction of the outer intermediate block 9 are defined by lateral grooves 4D and 4E. The outer main grooves 3D and the lateral grooves 4D and 4E allow the outer intermediate block 9 to be deformed in the tire width direction and reduce the rigidity in the lateral direction (tire width direction). However, by connecting the outer intermediate block 9 and the outer shoulder block 10 by the second raised portion 17, these blocks 9 and 10 can be integrally deformed with respect to a lateral load. That is, by providing the second raised portion 17, the lateral rigidity of the outer intermediate block 9 can be increased, and the steering performance or turning performance on the dry road surface can be improved.

  The second raised portion 17 is not provided in the entire outer main groove 3 </ b> D, but is partially provided in a region defined by a virtual line connecting the outer intermediate block 9 and the outer shoulder block 10. . Therefore, the influence which the 2nd raising part 17 has with respect to the flow of the water in the outer side main groove 3D is limited, and the drainage performance is ensured.

  The groove depth GD0 ′ of the outer main groove 3D in the second raised portion 17 is preferably set to be not less than 0.5 times and not more than 0.7 times the groove depth GD0 of the other part of the outer main groove 3D. When the groove depth GD0 ′ exceeds 0.7 times the groove depth GD0, the height of the second raised portion 17 is insufficient, and the outer intermediate block 9 is connected to the outer shoulder block 10 by the second raised portion 17. The effect of improving the rigidity in the lateral direction due to cannot be sufficiently obtained. On the other hand, when the groove depth GD0 'is less than the groove depth GD00.5, the depth of the outer main groove 3D is insufficient, and the drainage function of the outer main groove 3D is significantly impaired.

  Referring to FIGS. 1 and 2, the lateral groove 4F provided in the outer shoulder row 5E extends outward in the tire width direction beyond the ground contact end GEo on the outer side in the tire width direction. In the region from the outer middle row 5 to the outer shoulder row 5E, that is, the region from the outer middle to the outer side in the tire width direction of the tread portion 2, water entering the ground contact region to the road surface is tired relative to the tire circumferential direction. It has a velocity vector inclined outward in the width direction. The inclination angle increases toward the outer side of the tread portion 2 in the tire width direction. Accordingly, drainage can be effectively performed by providing the lateral grooves 4F that define the blocks of the outer shoulder row 5E so as to extend beyond the ground contact edge GEo on the outer side in the tire width direction.

  The lateral grooves 4D and 4E provided in the outer intermediate row 5D and the lateral grooves 4F provided in the outer shoulder row 5E are aligned and arranged in the tire circumferential direction. By this alignment, the second central main groove 3C and the grounding end GEo on the outer side in the tire width direction communicate with each other through the lateral grooves 4D, 4E, and 4F. At the time of turning, the area of the contact area to the road surface increases in a region including the outer shoulder row 5E, that is, a region outside the tread portion 2 in the tire width direction. Therefore, in order to improve the drainage performance at the time of turning, it is necessary to promote the flow of water in the lateral groove 4F toward the outer side in the tire width direction. By positioning the lateral grooves 4D and 4E of the outer intermediate row 5 with respect to the lateral groove 4F so as to communicate from the second central main groove 3C to the grounding end GEo, the flow of water in the lateral groove 4F during turning is promoted. Can drain effectively.

  Referring to FIGS. 1 and 2, as described above, the inner shoulder block 6A constituting the inner shoulder row 5A is provided with three inner longitudinal slits 6c to 6e. These inner vertical slits 6c to 6e are arranged in the tire circumferential direction so as not to overlap each other. The inner vertical slits 6c and 6e have one end terminated in the inner shoulder block 6A and the other end penetrating the side surface in the tire circumferential direction of the inner shoulder block 6A. Both ends of the inner vertical slit 6d terminate in the inner shoulder block 6A. The inner longitudinal slits 6c and 6e are set to have substantially the same position in the tire width direction. The inner longitudinal slit 6d disposed between the inner longitudinal slits 6c and 6e in the tire circumferential direction is provided at a position offset inward in the tire width direction with respect to the inner longitudinal slits 6c and 6e. In other words, the three inner vertical slits 6c to 6e are arranged in a staggered manner in the circumferential direction.

  Due to the influence of the camber angle, the shape of the ground contact area to the road surface tends to extend in the tire circumferential direction at the inner portion of the tread portion in the tire width direction, that is, the portion where the inner shoulder row 5A is provided (particularly during braking). . By providing the inner shoulder blocks 6 with the inner longitudinal slits 6c to 6e arranged in a staggered manner, the deformation and the ground pressure in the inner shoulder block 6 can be dispersed during braking. As a result, the braking performance on the dry road surface can be improved.

  Referring to FIGS. 1 and 2, as described above, the outer shoulder block 10 constituting the outer shoulder row 5E is provided with one outer longitudinal slit 10b. The outer longitudinal slit 10b is provided so as to cross the outer shoulder block 10 in the tire circumferential direction. That is, both ends of the outer vertical slit 10b penetrate the side surfaces of the outer shoulder block 10 in the tire circumferential direction, respectively.

  The outer intermediate block 9 and the outer shoulder block 10 are connected by the second raised portion 17. Therefore, when the outer intermediate block 9 is deformed with respect to a lateral load during turning, a lateral load (deformation in the tire width direction) is transmitted from the outer intermediate block 9 to the outer shoulder block 10. By providing the outer vertical slit 10b, the lateral load (deformation in the tire width direction) transmitted from the outer intermediate block 9 to the outer shoulder block 10 during turning can be reduced. As a result, turning performance on a dry road surface can be improved.

  From the above characteristics, in the tire 1 of the present embodiment, driving performance, braking performance, and turning performance can be improved while ensuring drainage performance.

  As described above, in the outer intermediate row 5D, the lateral grooves 4D that are “deep lateral grooves” and the lateral grooves 4E that are “shallow grooves with sipes” are alternately provided. The pair of outer intermediate blocks 9 located on both sides in the tire tire circumferential direction of the lateral grooves 4E that are “shallow grooves with sipes” are compared with the pair of outer intermediate blocks 9 that are located on both sides of the lateral grooves 4D that are “deep lateral grooves”. And are relatively firmly connected. In other words, the pair of outer intermediate blocks 9 located on both sides of the lateral groove 4E in the tire tire circumferential direction tend to be deformed integrally with respect to the longitudinal and lateral loads. Further, as described above, the outer intermediate block 9 and the outer shoulder block 10 are connected by the second raised portion 17 so that these blocks 9 and 10 are deformed integrally with respect to the lateral load. ing. From the above structure, as shown by the symbol U in FIG. 1, a pair of outer intermediate blocks 9 located on both sides of the tire groove circumferential direction of the lateral groove 4E which is a “shallow groove with sipes”, and these pair of outer intermediate blocks 9 and the pair of outer shoulder blocks 10 connected by the second raised portion 17 can be regarded as constituting one unit. The unit U tends to be deformed integrally with respect to the load in the front-rear direction and the lateral direction by the lateral groove 4E that is the “shallow groove with sipes” and the second raised portion 17. The presence of the unit U in the outer portion of the tread portion 2 in the tire width direction improves the turning performance particularly on the dry road surface.

Evaluation tests of driving performance (dry driving performance), braking performance (dry braking performance), and turning performance (dry turning performance) for Comparative Examples 1 and 2 and Examples 1 to 4 shown in Table 1 below Went. Moreover, about these, the hydroplaning performance was evaluated.
Specifications not specifically mentioned below are common to Comparative Examples 1 and 2 and Example 1. In particular, in both Comparative Examples 1 and 2 and Example 1, the tire size was 225 / 50R17, and the evaluation was performed when mounted on a 2000 cc FF sedan.

  In Table 1, “Characteristic 1” is the magnitude relationship between the groove widths GWb and GWc of the first and second central main grooves 3B and 3C and the groove widths GWa and GWd of the inner and outer main grooves 3A and 3D. As described above, in the embodiment of the present invention, the groove widths GWb and GWc are narrower than the groove widths GWa and GWd. Next, “feature 2” is a structure in which the lateral groove 4F provided in the outer shoulder row 5E extends outward in the tire width direction beyond the ground contact end GEo on the outer side in the tire width direction. The “feature 3” is a second raised portion provided in a region defined by a virtual line connecting the outer intermediate block 9 constituting the outer intermediate row 5D and the outer shoulder block 10 constituting the outer shoulder row 5E. 17. Furthermore, “feature 4” is a configuration in which the lateral grooves 4D and 4E of the outer intermediate row 5 are aligned with the lateral grooves 4F so as to communicate from the second central main groove 3C to the grounding end GEo.

  Regarding driving performance, each tire was mounted on a vehicle, and the acceleration time required from the dry road surface to 60 km / h was measured. The result of Comparative Example 1 is evaluated with an index of 100, and the larger the index is, the better the driving performance is.

  Regarding the braking performance, each tire was mounted on the vehicle, and the braking distance from the dry road surface to 100 km / h until the ABS braking was started and stopped was measured. The result of Comparative Example 1 is evaluated with an index of 100, and the larger the index, the better the braking performance.

  For turning performance, each tire is attached to the vehicle, and the vehicle runs on a dry road surface in a steady circular turn with a radius of R20 under the riding conditions of one passenger. The lap time was evaluated by an index. The result of Comparative Example 1 was evaluated with an index of 100, and the larger the index, the better the dry braking performance.

  For the hydroplaning performance, we measured the speed at which a difference in slip ratio between the left and right wheels of 10% was achieved by attaching each tire to the vehicle and using one wheel on a water channel with a depth of 8mm and one wheel on a straight road. The result of Comparative Example 1 is evaluated with an index of 100, and the greater the index, the better the straight running hydroplaning performance.

  In Example 1, the indexes of driving performance, braking performance, turning performance, and hydroplaning performance are all 102 or more, and good performance is obtained in any of these. On the other hand, Comparative Examples 1 and 2 have an index value smaller than that of Example 1 for any of the driving performance, braking performance, turning performance, and hydroplaning performance. In particular, Comparative Example 2 having “Feature 3” but not “Feature 2”, that is, Comparative Example in which the second raised portion 17 is provided, but the lateral groove 4F of the outer shoulder row 5E does not reach the grounding end GEo. 2, the hydroplaning performance index is 98. That is, in Comparative Example 2, the hydroplaning performance is significantly inferior.

  As described above, it can be understood from the comparison between Comparative Examples 1 and 2 and Example 1 that the pneumatic tire according to the present invention can improve the driving performance, the braking performance, and the turning performance while ensuring the drainage performance. .

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3A Inner main groove 3B 1st center main groove 3C 2nd center main groove 3D Outer main groove 4A, 4B, 4C, 4D, 4E, 4F Lateral groove 5A Inner shoulder row 5B Inner middle row 5C Center row 5D outer middle row 5E outer shoulder row 6 inner shoulder block 6a sipe 6b slit 6c, 6d, 6e inner longitudinal slit 7 inner middle block 7a side slit 7b sipe 8 center block 8a sipe 9 outer middle block 9a sipe 10 outer shoulder block 10a sipe 10b Outside vertical slit 11 Vertical groove 13 Shallow groove 14 Sipe 16 First raised portion 17 Second raised

Claims (7)

Four main grooves formed in the tread portion so as to extend in the tire circumferential direction;
A plurality of lateral grooves formed in the tread portion;
5 block rows each having a plurality of blocks arranged in the tire circumferential direction, each defined by the main groove and a pair of lateral grooves adjacent in the tire circumferential direction,
The mounting posture in the tire width direction relative to the vehicle body and the direction of rotation when the vehicle moves forward are specified.
The main groove is
An inner main groove located on the innermost side in the tire width direction when mounted on the vehicle;
An outer main groove located on the outermost side in the tire width direction when mounted on the vehicle;
A first central main groove adjacent to the outer side of the inner main groove in the tire width direction;
A second central main groove adjacent to the inner side in the tire width direction of the outer main groove,
The block sequence is
An inner shoulder row located on the inner side in the tire width direction of the inner main groove;
An outer shoulder row located on the outer side in the tire width direction of the outer main groove;
An inner intermediate row located between the inner main groove and the first central main groove;
An outer intermediate row located between the outer main groove and the second central main groove;
A central row located between the first central main groove and the second central main groove,
The groove width between the first central main groove and the second central main groove is wider than the groove width between the inner main groove and the outer main groove,
The lateral groove includes a plurality of first lateral grooves provided at intervals in the tire circumferential direction so as to define the blocks belonging to the inner shoulder row,
In the first lateral groove, a first raised portion for connecting a pair of the blocks belonging to the inner shoulder row is provided on the inner main groove side every other piece, and the first transverse groove of the first raised groove is provided on the first lateral groove. The depth is shallower than the depth of the other part of the first lateral groove,
In the outer main groove, a second raised portion is provided in a region defined by an imaginary line that connects the block belonging to the outer intermediate row and the block belonging to the outer shoulder row, in the second raised portion. The depth of the said outer main groove is a pneumatic tire shallower than the depth of the other part of the said outer main groove.   2. The air according to claim 1, wherein a depth of the first lateral groove in the first raised portion is set to be not less than 0.4 times and not more than 0.6 times a depth of another portion of the first lateral groove. Enter tire.   3. The depth of the outer main groove in the second raised portion is set to be not less than 0.5 times and not more than 0.7 times the depth of other portions of the outer main groove. Pneumatic tire described in 2. The lateral groove includes a plurality of second lateral grooves provided at intervals in the tire width direction so as to define the blocks belonging to the outer shoulder row.
The pneumatic tire according to any one of claims 1 to 3, wherein the second lateral groove extends in the tire width direction so as to exceed a ground contact end on the outer side in the tire width direction of the tread portion. The lateral groove includes a plurality of third lateral grooves provided at intervals in the tire width direction so as to define the blocks belonging to the outer intermediate row,
5. The pneumatic according to claim 4, wherein the second lateral groove and the third lateral groove are arranged in a state of being aligned so as to communicate from the second central main groove to the ground contact end on the outer side in the tire width direction. tire.   The pneumatic tire according to any one of claims 1 to 5, wherein the blocks belonging to the inner shoulder row are provided with a plurality of first slits arranged in a staggered manner in the circumferential direction.   The pneumatic tire according to any one of claims 1 to 6, wherein the blocks belonging to the outer shoulder row are provided with a plurality of second slits communicating in the circumferential direction.

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