JP2018111451A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of enhancing wet performance by devising a shape of a siping disposed at a tread part.SOLUTION: A pneumatic tire includes at least one row of a rib 10 in which a plurality of sipings 11 extending in a tire width direction is formed on each of a vehicle outer side area and a vehicle inner side area of a tread part 1. The siping 11 consists of a chamfered siping 12 and a non-chamfered siping 13. In the chamfered siping 12, one end part 12c terminates in the rib 10, on the other hand, the other end part 12d communicates with any one of main grooves 9 located at both sides of the rib 10. The chamfered sipings 12 communicating with each of main grooves 9 located at both sides of the rib 10 are alternately arranged in a tire circumferential direction. The non-chamfered siping 13 is arranged adjacent to one side of the chamfered siping 12 in at least the tire circumferential direction. Total extension length LBof the non-chamfered siping 13 at the vehicle outer side area and total extension length LBof the non-chamfered siping 13 at the vehicle inner side area satisfy relation of LB<LB.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can improve the dry performance and the wet performance in a balanced manner by devising the shape of a sipe provided in a tread portion.

  Conventionally, in a tread pattern of a pneumatic tire, a plurality of sipes are formed on ribs defined by a plurality of main grooves. By providing such sipes, drainage is ensured and wet performance is exhibited. However, when a large number of sipes are arranged in the tread portion for improving the wet performance, the rigidity of the ribs is lowered, so that the dry performance is lowered.

  Further, in a pneumatic tire, it is necessary to improve drainage of grooves and sipes in order to improve wet performance. As a technique for improving drainage, it has been proposed to provide a chamfered portion at the edge of a sipe provided in the tread portion (for example, Patent Document 1). In this case, the chamfered portion functions as a drainage channel, so that the drainage performance of the ground contact surface is improved and the wet performance of the tire is expected to be improved. However, when a chamfered portion is simply added to the sipe, the chamfered portion is crushed by deformation of the tread portion at the time of ground contact, and the chamfered portion does not function effectively as a drainage channel, and sufficient drainage is ensured. There is a concern that can not. Further, depending on the size of the chamfer, improvement in dry performance or wet performance may be insufficient.

Japanese Patent Laid-Open No. 2006-88469

  An object of the present invention is to provide a pneumatic tire capable of improving the dry performance and the wet performance in a balanced manner by devising the shape of the sipe provided in the tread portion.

In order to achieve the above object, a pneumatic tire according to the present invention includes, in a tread portion, a plurality of main grooves extending in the tire circumferential direction and a plurality of rows of ribs partitioned by the main grooves, and the vehicle mounting direction is The designated pneumatic tire has at least one row of ribs formed with a plurality of sipes extending in the tire width direction in each of the vehicle outer region and the vehicle inner region of the tread portion, and the sipe has at least one edge. A chamfered sipe having a chamfered portion on the edge and a non-chamfered sipe having no chamfered portion on the edge, and the chamfered sipe is a main groove having one end terminating in the rib and the other end positioned on both sides of the rib. Chamfered sipes communicating with either one of the main grooves located on both sides of the rib are alternately arranged in the tire circumferential direction, and the non-chamfered sipes Disposed adjacent to one side of at least the tire circumferential direction of the sipe, the total length LB _IN non chamfered sipe total length LB _OUT and the vehicle inner side area of the non-chamfered sipes on the vehicle outer side region is the relationship LB _OUT <LB _IN It is characterized by satisfying.

In the present invention, at least one rib of the plurality of rows of ribs has a plurality of sipes extending in the tire width direction, and the sipe has a chamfered sipe having at least one edge and a chamfered portion at the edge. Due to the non-chamfered sipe, it is possible to improve wet performance due to the chamfered sipe provided with the chamfered portion, leading to an improvement in drainage at the time of ground contact. On the other hand, the non-chamfered sipe without the chamfered portion coexists in the same rib adjacent to the tire circumferential direction of the chamfered sipe, so that the non-chamfered sipe bears the deformation of the tread portion at the time of ground contact, This contributes to suppression of crushing of the chamfered portion in the chamfer sipe. Further, in the chamfered sipe, one end of the chamfer ends in the rib while the other end communicates with one of the main grooves located on both sides of the rib, and communicates with each of the main grooves located on both sides of the rib. By arranging the chamfered sipe alternately in the tire circumferential direction, a wide ground contact area can be secured around the chamfered sipe, and crushing of the chamfered portion of the chamfered sipe can be effectively suppressed. Thereby, the wet performance can be improved. Further, since the total extension LB _OUT of the non-chamfered sipe in the vehicle outer region and the total extension LB _IN of the non-beveled sipe in the vehicle inner region satisfy the relationship of LB _OUT <LB _IN , This effectively acts on the load, can sufficiently ensure the rigidity of the tread portion, and leads to an improvement in dry performance.

  In the present invention, the distance L1 in the tire circumferential direction between the non-chamfered sipe and the chamfered sipe closest to the chamfered sipe is preferably 2 mm to 15 mm. Thereby, crushing of the chamfered portion of the chamfer sipe can be effectively suppressed.

In the present invention, it is preferable to satisfy a relation of _{1 <Nd IN / Cd IN ≦} 1.5 The depth Nd _IN non chamfered sipe depth Cd _IN and the vehicle inner side area of the chamfered sipes vehicle inner region. Thereby, crushing of the chamfered portion of the chamfer sipe can be effectively suppressed.

  In the present invention, the width Cw of the opening at the ground contact surface in the chamfered sipe is preferably 1.6 mm to 4.8 mm. Thereby, the drainage property at the time of grounding is securable.

In the present invention, the width Cw _OUT of the opening at the ground contact surface in the chamfer sipe in the vehicle outer region and the width Cw _IN of the opening at the ground contact surface in the chamfer sipe in the vehicle inner region are 1 <Cw _IN / Cw _OUT ≦ 3. 0.0 relationship is preferably satisfied. As a result, it is possible to improve drainage performance in the vehicle inner area, improve braking performance on the wet road surface, increase pattern rigidity in the vehicle outer area, and improve cornering performance on the dry road surface.

In the present invention, it is preferable that the groove area Ga _OUT in the main groove in the vehicle outer region and the groove area Ga _IN in the main groove in the vehicle inner region satisfy the relationship 1 <Ga _IN / Ga _OUT ≦ 1.4. As a result, it is possible to improve drainage performance in the vehicle inner area, improve braking performance on the wet road surface, increase pattern rigidity in the vehicle outer area, and improve cornering performance on the dry road surface.

  In the present invention, the non-chamfered sipe is bent in the tire circumferential direction in a plan view of the tread portion to have a bent portion, and the bent angle of the non-chamfered sipe is preferably 20 ° to 100 °. As a result, the wall surfaces of the non-chamfered sipe support each other in the deformation direction, thereby ensuring the pattern rigidity and leading to improved cornering performance on the dry road surface.

In the present invention, the hardness E _OUT of the rib tread rubber having the chamfered sipe in the vehicle outer region and the hardness E _IN of the rib tread rubber having the chamfered sipe in the vehicle inner region satisfy the relationship of E _OUT −E _IN ≧ 3. It is preferable. As a result, the cornering performance on the dry road surface can be improved, the chamfered portion of the chamfer sipe can be prevented from being crushed, and the braking performance on the wet road surface can be improved.

  In the present invention, it is preferable that the curvature radius TR of the virtual arc forming the tread profile and the curvature radius RR of the outer contour line of the rib having the chamfered sipe satisfy the relationship of TR> RR. Thereby, the drainage property of the rib at the time of grounding can be improved, and wet performance can be improved effectively.

  In the present invention, the “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, a standard rim is defined for JATMA, and a standard rim is defined for TRA. “Design Rim” or “Measuring Rim” for ETRTO. “Regular internal pressure” is the air pressure determined by each standard for each tire in the standard system including the standard on which the tire is based. The maximum air pressure is JATMA, and the table “TIRE LOAD LIMITS AT VARIOUS” is TRA. The maximum value described in “COLD INFRATION PRESURES”, “INFLATION PRESURE” for ETRTO, but 180 kPa when the tire is a passenger car.

It is meridian sectional drawing which shows the pneumatic tire which consists of embodiment of this invention. It is a perspective view which shows a part of tread part of the pneumatic tire which concerns on this invention. It is a top view which shows a part of tread part of the pneumatic tire which concerns on this invention. It is XX arrow sectional drawing of FIG. It is sectional drawing which shows the modification of the non-chamfered sipe formed in the tread part of the pneumatic tire which concerns on this invention. It is a top view which shows the other modification of the sipe formed in the tread part of the pneumatic tire which concerns on this invention. It is a top view which shows the other modification of the tread part of the pneumatic tire which concerns on this invention. The other modification of the non-chamfered sipe formed in the tread part of the pneumatic tire concerning the present invention is shown, and (a)-(c) is a top view of each modification. It is sectional drawing which shows the other modification of the tread part of the pneumatic tire which concerns on this invention. It is a top view which shows the other modification of the tread part of the pneumatic tire which concerns on this invention. It is a top view which shows the other modification of the tread part of the pneumatic tire which concerns on this invention. It is a top view which shows the other modification of the tread part of the pneumatic tire which concerns on this invention. The other modification of the chamfering sipe formed in the tread part of the pneumatic tire concerning the present invention is shown, and (a)-(d) is a sectional view of each modification.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic tire according to an embodiment of the present invention, and FIGS. 2 to 4 show a part of a tread portion of the pneumatic tire. In FIG. 1, CL is a tire equator line, and in FIGS. 2 and 3, Tc is a tire circumferential direction and Tw is a tire width direction.

  As shown in FIG. 1, in the pneumatic tire according to the embodiment of the present invention, the mounting direction with respect to the vehicle is specified, and IN is inside the tire equator line CL with respect to the vehicle when the tire is mounted on the vehicle. , And OUT represents an area outside the tire equator line CL with respect to the vehicle (hereinafter referred to as a vehicle outside area) when the tire is mounted on the vehicle. The pneumatic tire according to the embodiment of the present invention includes a tread portion 1 that extends in the tire circumferential direction and has a ring shape, and a pair of sidewall portions 2 and 2 that are disposed on both sides of the tread portion 1. A pair of bead portions 3 and 3 are provided inside the sidewall portion 2 in the tire radial direction.

  A carcass layer 4 is mounted between the pair of bead portions 3 and 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded from the inside of the tire to the outside around the bead core 5 disposed in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross-section is disposed on the outer periphery of the bead core 5.

  On the other hand, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between the layers. In the belt layer 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in a range of, for example, 10 ° to 40 °. A steel cord is preferably used as the reinforcing cord of the belt layer 7. For the purpose of improving high-speed durability, at least one belt cover layer 8 in which reinforcing cords are arranged at an angle of, for example, 5 ° or less with respect to the tire circumferential direction is disposed on the outer peripheral side of the belt layer 7. Yes. As the reinforcing cord of the belt cover layer 8, an organic fiber cord such as nylon or aramid is preferably used.

  In addition, although the tire internal structure mentioned above shows the typical example in a pneumatic tire, it is not limited to this.

  As shown in FIGS. 1 and 2, the tread portion 1 is formed with a plurality of main grooves 9 extending in the tire circumferential direction. The main groove 9 includes a main groove 9A located on the tire equator line CL and a pair of main grooves 9B, 9B located on the outer side in the tire width direction. The main grooves 9 define a plurality of rows of ribs 10 in the tread portion 1. The rib 10 includes a pair of ribs 10A and 10A located on both sides of the tire equator line CL, and a pair of ribs 10B and 10B located on the outer side in the tire width direction of the rib 10A.

  1 and FIG. 2 show an example in which three main grooves 9 are formed in the tread portion 1, but in order to achieve both drainability and securing of a ground contact area, the tread portion 1 has 3 It is preferable to provide ˜5 main grooves 9.

  As shown in FIG. 2, the rib 10 includes a plurality of sipes 11 extending in the tire width direction and blocks 20 partitioned by the plurality of sipes 11. These blocks 20 are arranged so as to be aligned in the tire circumferential direction. On the other hand, the sipe 11 includes a chamfered sipe 12 and a non-chamfered sipe 13. The sipe 11 is a narrow groove having a groove width of 0.5 mm to 1.6 mm and a depth of 2.0 mm or more when the rim is not assembled.

  As shown in FIG. 3, the chamfered sipe 12 is a sipe having a chamfered portion 14 on at least one of the edges 12 a and 12 b. 2 and 3, the chamfered portion 14 is provided on the edge 12a on one side over the entire length of the chamfered sipe 12. However, the chamfered portion 14 can be provided on both edges 12a and 12b. It can also be provided partially or intermittently along the extending direction. Further, the chamfered sipe 12 has one end 12 c terminating in the rib 10 and the other end 12 d communicating with either one of the main grooves 9 and 9 located on both sides of the rib 10. The chamfered sipes 12, 12 communicating with the main grooves 9, 9 located on both sides of the ribs 10 are alternately arranged in the tire circumferential direction, and the chamfered sipes 12 are arranged in a staggered manner in the tire circumferential direction as a whole. . As shown in FIG. 4, the chamfered portion 14 formed in the chamfered sipe 12 forms a triangle in a cross-sectional view orthogonal to the extending direction of the chamfered sipe 12. The chamfered sipe 12 has a depth of 1 mm or more except for the chamfered portion 14.

  The non-chamfered sipe 13 is a sipe that is provided in a region within 50 mm in the tire circumferential direction with the chamfered sipe 12 as a center and is not provided with a chamfered portion. The non-chamfered sipe 13 is disposed adjacent to at least one side of the chamfered sipe 12 in the tire circumferential direction. 2 and 3, non-chamfered sipe 13 is disposed adjacent to both sides of the chamfered sipe 12 in the tire circumferential direction on the rib 10A in the vehicle inner region, while non-chamfered on the rib 10A in the vehicle outer region. The sipe 13 is disposed adjacent to one side of the chamfered sipe 12 in the tire circumferential direction.

  The non-chamfered sipe 13 penetrates the rib 10 in the tire width direction. Thereby, there exists an inhibitory effect with respect to the crushing of the chamfering part 14 of the chamfering sipe 12 at the time of grounding. On the other hand, the non-chamfered sipe 13 may be configured as a closed sipe whose both ends are terminated in the rib 10 or a semi-closed sipe whose only one end is terminated in the rib 10. Further, the non-chamfered sipe 13 may be inclined with respect to the tire width direction, and may be bent or curved.

  The rib 10 may be provided with a groove other than the chamfered sipe 12 and the non-chamfered sipe 13. However, since the drainage in the rib 10 can be sufficiently secured by the chamfered sipe 12, it is preferable to provide only the chamfered sipe 12 and the non-chamfered sipe 13 from the viewpoint of increasing the ground contact area and improving the braking performance. .

In order to increase the contact area, it is better that the hardness of the tread rubber is smaller. On the other hand, in order to suppress the chamfered portion 14 from being crushed, the hardness of the tread rubber is better. In order to achieve both of these, the hardness of the tread rubber is preferably 58 to 75 as defined by JIS K6253. Particularly, the relationship between the hardness E _OUT of the tread rubber of the rib 10 having the chamfered sipe 12 in the vehicle outer region and the hardness E _IN of the tread rubber of the rib 10 having the chamfered sipe 12 in the vehicle inner region satisfies E _OUT −E _IN ≧ 3. It is good to meet. This contributes to improved cornering performance on dry road surfaces and braking performance on wet road surfaces.

In the pneumatic tire, the total extension LB _OUT of the non-chamfered sipe 13 in the vehicle outer region and the total extension LB _IN of the non-chamfered sipe 13 in the vehicle inner region satisfy the relationship LB _OUT <LB _IN . . Here, the total extensions LB _OUT and LB _IN of the non-chamfered sipe 13 are the sum of the sipe lengths of all the non-chamfered sipes 13 formed on the rib 10 in the vehicle outer region or the vehicle inner region. In particular, the ratio LB _IN / LB _OUT between the total extension LB _IN and the total extension LB _OUT of the non-chamfered sipe 13 is preferably in the range of 1.2 to 1.8. As described above, as a method of making the total extension LB _IN of the non-chamfered sipe 13 in the vehicle inner region larger than the total extension LB _OUT of the non-beveled sipe 13 in the vehicle outer region, the number of the non-chamfered sipes 13 is increased in the vehicle inner region. For example, the sipe length of the non-chamfered sipe 13 may be increased or the number of ribs to be applied may be increased. The sipe length is a length measured along the sipe extending direction at the center of the sipe groove width.

In addition to satisfying the relationship between the total extension LB _OUT and the total extension LB _IN , the total extension LA _OUT of the chamfer sipe 12 in the vehicle outer region and the total extension LA _IN of the non-chamfer sipe 13 in the vehicle inner region are The ratio LB _OUT / LA _OUT satisfying the relationship of LA _OUT ≦ LA _IN and / or the total extension LB _OUT of the non-chamfered sipe 13 in the vehicle outer region to the total extension LA _OUT of the chamfer sipe 12 in the vehicle outer region, and the vehicle inner side The ratio LB _IN / LA _IN of the total extension LB _IN of the non-chamfered sipe 13 in the region to the total extension LA _IN of the chamfered sipe 12 in the vehicle inner region satisfies the relationship of LB _OUT / LA _OUT ≦ LB _IN / LA _IN preferable.

  In the pneumatic tire described above, at least one rib 10 of the plurality of rows of ribs 10 has a plurality of sipes 11 extending in the tire width direction, and the sipe 11 has a chamfered portion 14 on at least one edge 12a, 12b. By comprising the chamfered sipe 12 and the non-chamfered sipe 13 having no chamfered portion at the edge, the drainage at the time of grounding can be improved due to the chamfered sipe 12 provided with the chamfered portion 14, and the wet performance. It leads to improvement. On the other hand, the non-chamfered sipe 13 that is not provided with the chamfered portion coexists in the same rib 10 adjacent to the tire circumferential direction of the chamfered sipe 12, so that the non-chamfered sipe 13 of the tread portion 1 at the time of ground contact A deformation | transformation is borne and it contributes to suppression of the crushing of the chamfer 14 in the chamfer sipe 12.

Further, in the chamfered sipe 12, one end portion 12 c terminates in the rib 10, while the other end portion 12 d communicates with one of the main grooves 9 positioned on both sides of the rib 10, and is positioned on both sides of the rib 10. Since the chamfered sipes 12 communicating with the main grooves 9 are alternately arranged in the tire circumferential direction, a large ground contact area can be secured around the chamfered sipe 12, and the chamfered portion 14 of the chamfered sipe 12 is crushed. Can be effectively suppressed. Thereby, the wet performance can be improved. Further, since the total extension LB _OUT of the non-chamfered sipe 13 in the vehicle outer region and the total extension LB _IN of the non-beveled sipe 13 in the vehicle inner region satisfy the relationship LB _OUT <LB _IN , It acts effectively against a great load, can sufficiently ensure the rigidity of the tread portion 1, and leads to an improvement in dry performance.

  In the pneumatic tire, as shown in FIG. 3, the recessed region of the chamfered sipe 12 including the chamfered portion 14 and the recessed region of the non-chamfered sipe 13 that is closest to the chamfered sipe 12 among the non-chamfered sipe 13 are closest. The distance in the tire circumferential direction at the position to be used is the distance L1. The distance L1 is preferably 2 mm to 15 mm, and more preferably 4 mm to 11 mm. Thus, by appropriately setting the distance L1, the non-chamfered sipe 13 can effectively suppress the chamfered portion 14 of the chamfered sipe 12 from being crushed. Here, if the distance L1 is smaller than 2 mm, the rigidity of the rib 10 is lowered in the region sandwiched between the chamfered sipe 12 and the non-chamfered sipe 13, and it becomes difficult to ensure the grounding property by falling down the region. There is a tendency for performance to decrease.

In FIG. 3, the inclination angles of the chamfered sipe 12 and the non-chamfered sipe 13 with respect to the tire circumferential direction are an inclination angle θ _C and an inclination angle θ _N , respectively. At this time, the inclination angle θ _C of the chamfered sipe 12 and the inclination angle θ _N of the non-chamfered sipe 13 are preferably configured to satisfy the relationship of θ _C −30 ° ≦ θ _N ≦ θ _C + 30 °. By setting the inclination angles θ _C and θ _N in this manner, the chamfered portion 14 of the chamfer sipe 12 can be effectively prevented from being crushed. Note that the inclination angle θ _N of the non-chamfered sipe 13 is an inclination angle specified in a range equivalent to the length of the chamfered sipe 12 in the tire width direction.

As shown in FIG. 4, in the chamfered sipe 12 and the non-chamfered sipe 13, the depth from the ground surface to the groove bottom of the sipe is defined as a depth Cd and a depth Nd, respectively. In this case, it is preferable to satisfy a relation of _{1 <Nd IN / Cd IN ≦} 1.5 The depth Nd _IN non chamfered sipe depth Cd _IN and the vehicle inner side area of the chamfered sipes vehicle inner region. More preferably, 1.1 <Nd _IN / Cd _IN ≦ 1.4. By thus setting appropriately the depth Nd _IN depth Cd _IN, it is possible to effectively suppress the collapse of the chamfered portion 14 of the chamfer sipe 12. Here, when the ratio of the depth Cd _IN depth Nd _IN is larger than 1.5, rigidity of the rib 10 of the vehicle inner side region is lowered dent collapse block 20, wet performance tends to be lowered.

  In FIG. 4, the width of the opening at the ground contact surface of the chamfered sipe 12 is defined as a width Cw. The width Cw of the opening is measured along the direction orthogonal to the extending direction of the chamfered sipe 12. At this time, the width Cw of the opening may be configured to be 1.6 mm to 4.8 mm. By configuring the chamfered sipe 12 in this way, it is possible to ensure drainage at the time of ground contact. Here, if the width Cw of the opening at the ground contact surface of the chamfered sipe 12 is smaller than 1.6 mm, the drainage improvement effect is small. If the width Cw is larger than 4.8 mm, the ground contact area becomes small, and the wet performance and dry road surface are reduced. There is a tendency for the cornering performance of the to decrease.

  FIG. 5 shows a modification of the non-chamfered sipe formed on the tread portion of the pneumatic tire according to the present invention. As shown in FIG. 5, the width of the opening at the ground contact surface of the non-chamfered sipe 13 is defined as a width Nw. The width Nw of the opening is measured along a direction orthogonal to the extending direction of the non-chamfered sipe 13. In FIG. 5, the width Nw of the non-chamfered sipe 13 is gradually increased from the bottom toward the opening. Since the non-chamfered sipe 13 is formed in this manner, the burden amount on the deformation of the tread portion 1 of the non-chamfered sipe 13 is increased, and the chamfered portion 14 of the chamfered sipe 12 can be effectively crushed.

FIG. 6 shows another modification of the sipe formed on the tread portion of the pneumatic tire according to the present invention. As shown in FIG. 6, the opening at the ground contact surface of the chamfer sipe 12 in the vehicle inner region is formed wider than the opening at the ground contact surface of the chamfer sipe 12 in the vehicle outer region. That is, the width Cw _OUT of the opening portion of the chamfer sipe 12 in the vehicle outside region and the width Cw _IN of the opening portion of the chamfer sipe 12 in the vehicle inside region satisfy the relationship of 1 <Cw _IN / Cw _OUT ≦ 3.0. It is configured. By appropriately setting the width Cw _IN with respect to the width Cw _{OUT in} this way, the drainage performance in the vehicle inner area is improved, the braking performance on the wet road surface is improved, and the pattern rigidity in the vehicle outer area is increased. It becomes possible to improve the cornering performance on the dry road surface. Here, if the ratio of the width Cw _OUT width Cw _IN exceeds 3.0, the rigidity of the block 20 in the vehicle inner side region is excessively small, the braking performance on wet road surface tends to decrease.

FIG. 7 shows another modification of the tread portion of the pneumatic tire according to the present invention. As shown in FIG. 7, the main groove 9B in the vehicle inner region is formed wider than the main groove 9B in the vehicle outer region. That is, the groove area Ga _OUT of the main groove 9 in the vehicle outer region and the groove area Ga _IN of the main groove 9 in the vehicle inner region satisfy the relationship 1 <Ga _IN / Ga _OUT ≦ 1.4. . Thus the groove area Ga _IN By setting appropriately with respect to groove area Ga _OUT, enhance the drainage property at the vehicle inner area, thereby improving the braking performance on wet road surface, the pattern rigidity of the vehicle outer side region And cornering performance on dry roads can be improved. Here, when the ratio groove area Ga _OUT of groove area Ga _IN is larger than 1.4, the rigidity of the block 20 of the vehicle inner side region is excessively reduced, the braking performance on wet road surface tends to decrease.

  FIGS. 8A to 8C show other modified examples of the non-chamfered sipe formed on the tread portion of the pneumatic tire according to the present invention. As shown in FIG. 8A, the non-chamfered sipe 13 is bent in the tire circumferential direction in a plan view of the tread portion 1 and has a bent portion 13a. The bending angle θ1 of the non-chamfered sipe 13 is in the range of 20 ° to 100 °. Here, the bending angle θ1 of the non-chamfered sipe 13 means that when the non-chamfered sipe 13 has a part on one side and a part on the other side with the bent part 13a as a boundary, the part on the other side with respect to the extending direction of the part on one side Means the inclination angle. Since the non-chamfered sipe 13 has the bent portion 13a having such a bend angle θ1, the blocks 20 of the ribs 10 divided by the non-chamfered sipe 13 are not easily displaced in the lateral direction (tire width direction). That is, the wall surfaces of the non-chamfered sipe 13 can support each other in any deformation direction, and the pattern rigidity can be ensured, leading to an improvement in cornering performance on the dry road surface. However, the configuration in which the bending angle θ1 is larger than 90 ° and both end portions of the non-chamfered sipe 13 communicate with the same main groove 9 among the main grooves 9 on both sides of the rib 10 is not included. Further, in addition to the case shown in FIG. 8 (a), the case has a mountain shape that is convex in the tire circumferential direction as shown in FIG. 8 (b), or two bent portions 13a as shown in FIG. 8 (c). The case where it has and is formed in step shape as a whole can be illustrated.

  FIG. 9 shows another modification of the tread portion of the pneumatic tire according to the present invention. In FIG. 9, each rib 10 is formed with a chamfered sipe 12 and a non-chamfered sipe 13 as in the above-described embodiment. An outer contour line that defines the tread surface of the rib 10 when assuming an arc R passing through the tire width direction end points E1, E2, E3, and E4 of the two main grooves 9 located in the tire central portion in the tire meridian cross-sectional view Protrudes outward in the tire radial direction from the arc R. That is, the curvature radius TR of the arc R forming the tread profile and the curvature radius RR of the outer contour line of the rib 10 having the chamfered sipe 12 satisfy the relationship of TR> RR. Thereby, the drainage property of the rib 10 at the time of grounding can be improved, and wet performance can be improved effectively. The radius of curvature TR and the radius of curvature RR are measured in a state in which the tire is assembled on the normal rim and the normal internal pressure is filled.

  10 to 12 show another modification of the tread portion of the pneumatic tire according to the present invention. 10 and 11 show an example in which the above-described chamfered sipe 12 and non-chamfered sipe 13 are applied to a rib 10 defined by four main grooves 9 extending in the tire circumferential direction, and FIG. This is an example applied to the rib 10 partitioned by the main groove 9 of the book. 10 and 11, the pair of main grooves 9A and 9A located on both sides of the tire equator line CL and the pair of main grooves 9B and 9B located on the outer side in the tire width direction are positioned on the tire equator line CL. The rib 10A to be performed and a pair of ribs 10B and 10B located on the outer side in the tire width direction are partitioned. In FIG. 12, a main groove 9A located near the tire equator line CL, a pair of main grooves 9B and 9B located on the outer side in the tire width direction, and a pair of main grooves 9C located on the outermost side in the tire width direction. , 9C define a rib 10A located on the tire equator line CL, a pair of ribs 10B, 10B located on the outer side in the tire width direction, and a rib 10C located on the outer side in the tire width direction of the rib 10B in the vehicle inner region. Has been.

In FIG. 10, more non-chamfered sipes 13 are arranged on the rib 10B in the vehicle inner region than on the rib 10B in the vehicle outer region. In FIG. 11, the non-chamfered sipe 13 of the rib 10B in the vehicle outer region extends parallel to the tire width direction, while the non-chamfered sipe 13 of the rib 10B in the vehicle inner region is inclined with respect to the tire width direction. doing. In FIG. 12, the chamfered sipe 12 and the non-chamfered sipe 13 are disposed only on the pair of ribs 10B and 10B, and the non-chamfered sipe 13 is disposed on the rib 10B in the vehicle inner region more than the rib 10B in the vehicle outer region. Yes. That is, in any of the modes of FIGS. 10 to 12, the total extension LB _OUT of the non-chamfered sipe 13 in the vehicle outer region and the total extension LB _IN of the non-chamfered sipe 13 in the vehicle inner region have a relationship of LB _OUT <LB _IN . It is configured to meet.

  FIGS. 13A to 13D show other modified examples of the chamfer sipe formed on the tread portion of the pneumatic tire according to the present invention. As shown in FIG. 13A, a chamfered portion 14 is formed at one edge of the chamfered sipe 12 in a cross-sectional view orthogonal to the extending direction of the chamfered sipe 12, and the cross-sectional shape of the chamfered portion 14 is rectangular. It is. Thus, by making the cross-sectional shape of the chamfered portion 14 rectangular, a sufficient groove volume can be secured against deformation of the tread portion 1 at the time of ground contact, and drainage can be improved. On the other hand, as the cross-sectional shape of the chamfered portion 14 of the chamfered sipe 12, in addition to that shown in FIGS. 4 and 13A, the contour of a curve that protrudes inward in the tire radial direction as shown in FIG. In the case of having a line, in the case of having a curved contour line that protrudes outward in the tire radial direction as shown in FIG. 13C, the case of having a triangular shape as shown in FIG. it can.

A pneumatic tire having a tire size of 195 / 65R15 and having a plurality of main grooves extending in the tire circumferential direction and a plurality of rows of ribs defined by the main grooves in the tread portion. Presence / absence of sipe, ratio of total extension LB _IN of non-chamfered sipe in vehicle inner region to total extension LB _OUT of non-chamfered sipe in vehicle outer region (LB _IN / LB _OUT ), distance L1 between chamfered sipe and non-chamfered sipe mm), the ratio (Nd _IN / Cd _IN ) of the non-chamfered sipe depth Nd _{IN in} the vehicle inner region to the chamfered sipe depth Cd _{IN in} the vehicle inner region, and the width Cw _OUT of the chamfered sipe opening in the vehicle outer region. (mm), a width Cw _iN of the opening of the chamfer sipe vehicle inside area with respect to the width Cw _OUT of the opening of the chamfer sipe on the vehicle outer side area ratio (Cw _iN / Cw _OUT), on the vehicle outer side region The ratio of the major groove of the groove area Ga _IN of the vehicle inner side region to the groove area Ga _OUT groove (Ga _IN / Ga _OUT), the bending angle of the non-chamfered sipe, hardness E _OUT and the vehicle inner side of the tread rubber ribs on the vehicle outer side region Conventional examples in which the difference between the region rib tread rubber hardness E _IN (E _OUT −E _IN ) and the presence or absence of the rib protruding outward in the tire radial direction are set as shown in Tables 1 and 2, and Comparative Examples 1 to 2 3 and Examples 1 to 9 were manufactured.

  These test tires were evaluated for braking performance on wet road surfaces and steering stability performance on dry road surfaces by the following test methods, and the results are also shown in Tables 1 and 2.

Braking performance on wet surfaces:
Each test tire is mounted on a wheel with a rim size of 15 x 6 J, mounted on a front-wheel drive vehicle with a displacement of 1500 cc, and the braking distance from an initial speed of 80 km / h to a complete stop is measured on a wet road surface of 2 mm water depth with an air pressure of 230 kPa. did. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. The larger the index value, the better the braking performance on the wet road surface.

Steering stability on dry roads:
Each test tire was assembled on a wheel with a rim size of 15 × 6 J, mounted on a front-wheel drive vehicle with a displacement of 1500 cc, and an air pressure of 230 kPa, and a sensory evaluation was performed by a test driver on a dry road surface. The evaluation results are shown as an index with the conventional example being 100. The larger the index value, the better the steering stability performance on the dry road surface.

  As can be seen from Tables 1 and 2, the tires of Examples 1 to 9 were devised in the shape of the sipe provided in the tread portion, so that the braking performance on the wet road surface and the dry road surface were compared with the conventional examples. The steering stability performance at the same time was improved.

  On the other hand, in Comparative Example 1, since the total extension of the non-chamfered sipe in the vehicle outer region and the total extension of the non-chamfered sipe in the vehicle inner region were set to be equal, it was not possible to obtain the effect of improving the steering stability performance on the dry road surface. It was. In Comparative Example 2, since no sipes were provided on the ribs, the effect of improving the braking performance on the wet road surface could not be sufficiently obtained. In Comparative Example 3, since only the sipe having no chamfered portion is disposed on the rib, the effect of improving the braking performance on the wet road surface cannot be sufficiently obtained, and the effect of improving the steering stability on the dry road surface is small. It was.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 9 Main groove 10 Rib 11 Sipe 12 Chamfering sipe 12a, 12b Edge 12c, 12d End part 13 Non-chamfered sipe 14 Chamfering part

Claims (9)

In the pneumatic tire in which the tread portion includes a plurality of main grooves extending in the tire circumferential direction and a plurality of rows of ribs partitioned by the main grooves, and the vehicle mounting direction is specified.
A chamfered sipe having at least one row of ribs formed with a plurality of sipes extending in the tire width direction in each of the vehicle outer side region and the vehicle inner side region of the tread portion, the sipe having a chamfered portion at at least one edge; It comprises a non-chamfered sipe that does not have a chamfered portion at the edge, and the chamfered sipe terminates in one end of the rib while the other end communicates with one of the main grooves located on both sides of the rib, Chamfered sipes communicating with each of the main grooves located on both sides of the rib are alternately arranged in the tire circumferential direction, and the non-chamfered sipes are arranged adjacent to at least one side of the tire circumferential direction of the chamfered sipe, be the total length LB _OUT non chamfer sipes and the total length LB _iN non chamfered sipes of the vehicle inner side region is characterized by satisfying the relationship of LB _OUT <LB _iN Pneumatic tire.   The pneumatic tire according to claim 1, wherein a distance L1 in a tire circumferential direction between the non-chamfered sipe and the chamfered sipe closest to the chamfered sipe is 2 mm to 15 mm. Claim 1 or the depth Nd _IN non chamfered sipe depth Cd _IN and the vehicle inner side area of the chamfered sipes of the vehicle inner side region is characterized by satisfying the relation of _{1 <Nd IN / Cd IN ≦} 1.5 2. The pneumatic tire according to 2.   The pneumatic tire according to any one of claims 1 to 3, wherein a width Cw of an opening at a ground contact surface of the chamfered sipe is 1.6 mm to 4.8 mm. The relationship 1 <Cw _IN / Cw _OUT ≦ 3.0 between the width Cw _OUT of the opening at the ground contact surface in the chamfer sipe in the vehicle outer region and the width Cw _IN of the opening at the ground contact surface in the chamfer sipe in the vehicle inner region. The pneumatic tire according to claim 1, wherein the pneumatic tire is satisfied. 6. The groove area Ga _OUT of the main groove in the vehicle outer region and the groove area Ga _IN of the main groove in the vehicle inner region satisfy the relationship 1 <Ga _IN / Ga _OUT ≦ 1.4. The pneumatic tire according to any one of the above.   The non-chamfered sipe is bent in the tire circumferential direction in a plan view of the tread portion to have a bent portion, and the bent angle of the non-chamfered sipe is 20 ° to 100 °. The pneumatic tire according to any one of the above. The hardness E _OUT of the rib tread rubber having the chamfered sipe in the vehicle outer region and the hardness E _IN of the rib tread rubber having the chamfered sipe in the vehicle inner region satisfy the relationship of E _OUT −E _IN ≧ 3 The pneumatic tire according to any one of claims 1 to 7.   The air according to any one of claims 1 to 8, wherein a radius of curvature TR of the arc forming the tread profile and a radius of curvature RR of the outer contour line of the rib having the chamfered sipe satisfy a relationship of TR> RR. Enter tire.

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