JP6002032B2 - tire - Google Patents

Description

  The present invention relates to a tire having a tread portion having a grounding surface that contacts a road surface, the tread portion including a lateral groove extending along a tread width direction, and a width direction land portion formed by the lateral groove.

  Conventionally, in order to secure on-snow performance such as braking performance and acceleration performance on a snowy road surface, a technology for forming sipes and cuts (hereinafter referred to as sipes including both) in a land portion formed on a tread portion of a tire is widely used. Used (see, for example, Patent Document 1).

JP-A-6-234307 (FIG. 1 and the like)

  However, simply increasing the sipe formed in the land to ensure the performance on snow will reduce the rigidity of the land, resulting in a decrease in the ground contact area due to the collapse of the land, There has been a problem that driving performance and acceleration performance on wet road surfaces are degraded.

  Therefore, the present invention has been made in view of such a situation, and an object thereof is to provide a tire capable of achieving both on-snow performance and wet performance at a high level.

  A first feature according to the present invention is that, in a tread portion (tread portion 2) having a ground contact surface that comes in contact with a road surface, a lateral groove (lateral groove 10) extending in the tread width direction and the lateral groove are spaced in the tire circumferential direction. A tire (pneumatic tire 1) including a plurality of widthwise land portions (widthwise land portions 20) partitioned by being formed, and an outer groove end portion (outer groove end portion 10out on the outer side in the tread width direction of the lateral groove. ) Is arranged so as to reach the grounding end portion (grounding end portion TE) on the outer side in the tread width direction of the grounding surface, and the inner groove end portion (inner groove end portion 10in) on the inner side in the tread width direction of the lateral groove is When the ground half width (ground half width Wh) is from the tire equator plane to the ground contact edge, the tire is disposed within 15% of the ground half width from the tire equator plane. A plurality of circumferential narrow grooves (circumferential narrow grooves 30) extending continuously in the direction are formed, and a plurality of sipes extending in a direction intersecting the direction in which the lateral grooves extend are formed in the width direction land portion. The sipe 50) is formed, and the tread portion is a central region (central region) closest to the tire equator surface among regions determined by equally dividing a region from the tire equator surface to the ground contact end portion. Cn) and an outer region (outer region Sh) located on the outer side in the tread width direction than the central region, and the plurality of circumferential narrow grooves are disposed in the central region, The gist of the lateral groove (groove area DSout) is larger than the groove area of the lateral groove in the central region.

  In such a tire, a plurality of circumferential grooves are formed in the central region, and the groove area of the lateral grooves in the outer region is larger than the groove area of the lateral grooves in the central region. In other words, the tire has a circumferential groove in the central region, thereby increasing the edge component in the tread width direction (lateral direction), increasing the lateral grip on the road surface on snow, and increasing the lateral groove toward the inner side in the tread width direction. By reducing the groove area, it is possible to suppress a decrease in ground contact area due to a decrease in rigidity of the land portion in the width direction and to suppress a decrease in wet performance. Moreover, since the sipe is formed in the width direction land part, compared with the case where the sipe is not formed, the edge effect can be improved and the performance on snow can be improved.

  In addition, since the groove area of the lateral groove in the outer region is larger than the groove area of the lateral groove in the central region, by taking a lot of snow into the lateral groove in the outer region, the snow column shear force in the outer region is increased and the performance on snow is improved. Can be made.

  Thus, according to such a tire, it is possible to achieve both on-snow performance and wet performance at a high level.

  According to the characteristics of the present invention, it is possible to provide a tire capable of achieving both on-snow performance and wet performance at a high level.

FIG. 1 is a partial development view of a tread portion 2 of a pneumatic tire 1 according to an embodiment of the present invention. FIG. 2 is a partially enlarged view of the tread portion 2 of the pneumatic tire 1 according to the embodiment of the present invention. FIG. 3 is a conceptual diagram when the pneumatic tire 1 according to the embodiment of the present invention travels on a snowy road surface. FIG. 4 is a partial development view of the tread portion of the pneumatic tire according to the first modification of the present invention. FIG. 5 is a diagram illustrating a three-dimensional example formed in the pneumatic tire according to the second modification of the present invention. FIG. 6 is a partial development view of a tread portion of a pneumatic tire according to Modification 4 of the present invention. FIG. 7 is a partial development view of a tread portion of a pneumatic tire according to a comparative example (conventional example).

  Next, an embodiment of a tire according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings may be contained.

(1) Overall Schematic Configuration of Tire FIG. 1 is a partial development view of a tread portion 2 of a pneumatic tire 1 according to this embodiment. FIG. 2 is a partially enlarged view of the tread portion 2 of the pneumatic tire 1 according to the present embodiment. The pneumatic tire 1 is a pneumatic tire mainly mounted on a passenger car.

  Moreover, the pneumatic tire 1 according to the present embodiment includes a pattern for designating the tire rotation direction Tr. For example, in the pneumatic tire 1, the tire rotation direction Tr when the vehicle moves forward is indicated on the side portion as an arrow. The tire rotation direction Tr specified by the pneumatic tire 1 according to the present embodiment is a direction of an arrow along the tire circumferential direction Tc in FIG. 1 (downward direction in FIG. 1). The circumferential direction Tc is parallel. Moreover, in this embodiment, the pneumatic tire 1 has the tread part 2 which has a grounding surface which contacts a road surface. In addition, although the carcass layer, the belt layer, etc. are provided in the pneumatic tire 1 as an internal structure, description is abbreviate | omitted here.

  The tread portion 2 is formed with a lateral groove 10 extending in the tread width direction Tw. Further, the tread portion 2 is provided with a plurality of width direction land portions 20 by forming a plurality of lateral grooves at intervals in the tire circumferential direction Tc. Specifically, the lateral groove 10 is inclined with respect to the tread width direction Tw and extends in the tread width direction Tw while being curved. In the present embodiment, the lateral groove 10 formed on one side of the tread width direction Tw and the lateral groove 10 formed on the other side of the tread width direction Tw with the tire equatorial plane CL as a boundary are the tire circumferential direction Tc. Are offset and shifted in phase by a predetermined interval.

  The tread portion 2 includes a central region Cn closest to the tire equator plane CL among regions defined by equally dividing the region from the tire equator plane CL to the ground contact end TE, and a tread width larger than the central region Cn. And an outer region Sh located outside the direction Tw.

  Here, the contact end portion TE of the contact surface of the tread portion 2 is a state in which a normal internal pressure and a normal load are applied to the pneumatic tire 1 attached to the normal rim, and the pneumatic tire 1 is in contact with the road surface. The edge part of the tread width direction Tw of a ground plane is shown. The regular rim refers to a standard rim in an applicable size defined in the year 2011 version of JATMA (Japan Automobile Tire Association). The normal internal pressure is the air pressure corresponding to the maximum load capacity of JATMA's Year Book 2011 version, and the normal load is the load corresponding to the maximum load capacity when the single wheel of JATMA's Year Book 2011 version is applied. . Outside Japan, the standards governing these are determined by industry standards that are valid in the region where the tire is produced or used. For example, in the United States, it is “The Year Book of The Tire and Rim Association Inc.”, and in Europe it is “The Standards Manual of the European Tire and Rim Technical Organization”.

  In other words, the central region Cn is composed of two regions located on the innermost side in the tread width direction Tw among the regions Wd of which both ends TE in the tread width direction Tw and the width W of the TE are equally divided into four. . Further, an outer region Sh is provided adjacent to the outer side of the central region Cn in the tread width direction Tw. In the present embodiment, each lateral groove 10 extends from the central region Cn over the outer region Sh.

(2) Configuration of circumferential narrow groove A plurality of circumferential narrow grooves 30 extending continuously in the tire circumferential direction Tc are formed in the tread portion 2. In the example of FIG. 1, five circumferential narrow grooves 30 are formed. Details will be described below.

  The plurality of circumferential narrow grooves 30 include a central circumferential narrow groove 31 extending in the tire circumferential direction along the tire equatorial plane CL, and an outer circumference formed outside the central circumferential narrow groove 31 in the tread width direction Tw. Direction narrow groove 32. The central circumferential narrow groove 31 is a linear groove in the tread surface view. The shape of the central circumferential narrow groove 31 may extend linearly or zigzag. In addition, the center circumferential direction fine groove does not need to be provided like the modification 2 mentioned later.

  The outer circumferential narrow groove 32 extends continuously in the tire circumferential direction Tc on the outer side in the tread width direction Tw than the central circumferential narrow groove 31 or the tire equatorial plane CL. In the present embodiment, a case where two outer circumferential narrow grooves 32 are formed outside the central circumferential narrow groove 31 outside the tread width direction Tw will be described as an example. The number of outer circumferential narrow grooves 32 is not limited to this, and may be one or three or more.

  The outer circumferential narrow groove 32 extends in the tire circumferential direction Tc so as to cross the width direction land portion 20. Further, on the width direction land portion 20, the outer circumferential narrow groove 32 extends in a direction inclined at a predetermined angle with respect to the tire circumferential direction Tc. Specifically, on the width direction land portion 20, the angle θ32 formed by the extending direction of the outer circumferential narrow groove 32 and the tire circumferential direction Tc is within 20 °. Note that the angle θ32 is preferably within 15 °, and more preferably within 10 °. As described above, the outer circumferential narrow groove 32 continuously extends in the tire circumferential direction Tc while repeating the inclination on the widthwise land portion 20.

  The circumferential narrow groove 30 including the central circumferential narrow groove 31 and the outer circumferential narrow groove 32 has a groove width that does not close when the width-direction land portion 20 is grounded. In the present embodiment, the groove width of the circumferential narrow groove 30 is preferably in the range of 20% to 60% of the maximum groove width D10out (described later) in the lateral groove 10. This is because when the groove width of the circumferential narrow groove 30 is smaller than 20% of the maximum groove depth D10out (described later), the groove walls come into contact with each other during lateral input, and deformation of the block edge in the lateral direction on snow is suppressed. This is because the edge effect by the circumferential narrow groove 30 cannot be ensured, and when it is larger than 60% of the maximum groove width D10out (described later), the ground contact area is reduced and the frictional force is sufficiently obtained on the snow and on the wet road surface. This is because it cannot be secured. The groove width of the circumferential narrow groove 30 is preferably in the range of 1.5 mm to 5.5 mm, and more preferably 3 mm to 4.5 mm.

  The groove depth in the tire radial direction of the circumferential narrow groove 30 is preferably in the range of 30% to 100% of the groove depth of the lateral groove 10 in the tire radial direction. This is because if the groove depth in the tire radial direction of the circumferential narrow groove 30 is smaller than 30%, the block edge does not deform laterally on the snow, and the edge effect by the circumferential narrow groove 30 cannot be ensured, and the snow maneuvering is performed. This is because stability cannot be improved.

(3) Configuration of lateral groove In the present embodiment, the lateral groove 10 communicates with the central circumferential narrow groove 31 and the outer circumferential narrow groove 32. The lateral groove 10 is a groove having a groove width larger than 1.5 mm, extends in the tread width direction Tw, and is applied to the end portion TE of the ground contact surface of the tread portion 2 in a state where a normal load is applied with a normal internal pressure. It is an opening groove. Further, the outer groove end portion 10out on the outer side of the lateral groove 10 in the tread width direction Tw is disposed so as to reach the grounding end portion TE on the outer side of the grounding surface in the tread width direction Tw. Specifically, the outer groove end portion 10out may be disposed on the outer side of the tread width direction Tw with respect to the position of the ground end portion TE or the ground end portion TE.

  Further, the inner groove end portion 10in on the inner side in the tread width direction Tw of the lateral groove 10 is within 15% of the ground contact half width Wh from the tire equator surface CL when the ground contact half width Wh from the tire equator surface CL to the ground contact end TE is set. Is placed inside.

  Here, the ground half width Wh is indicated as W / 2 with respect to the ground width W in the tread width direction Tw of the ground plane. In the example of FIG. 1, a width W1 of 15% of the ground half width Wh is shown. The inner groove end portion 10in on the inner side of the lateral groove 10 in the tread width direction Tw is disposed within the range of the width W1 from the tire equatorial plane CL toward the outer side of the tread width direction Tw.

  As shown in FIG. 1, it is preferable that the lateral groove 10 communicates with the central circumferential narrow groove 31. The inner groove end portion 10 in of the lateral groove 10 may communicate with the central circumferential narrow groove 31. With such a configuration, the drainage performance from the central circumferential narrow groove 31 to the lateral groove 10 can be improved, and the wet performance can be enhanced. In the present embodiment, the groove area DSout of the lateral groove 10 in the outer region Sh is larger than the groove area DSin of the lateral groove 10 in the central region Cn. Specifically, as shown in FIG. 2, the groove area DSin of the region A10in in the central region Cn of the lateral groove 10 and the groove area DSout of the region A10out in the outer region Sh of the lateral groove 10 are: groove area DSin <groove area Satisfies the DSout relationship.

  As described above, in the pneumatic tire 1 according to this embodiment, the groove area DSin of the central region Cn and the groove area DSout of the outer region Sh satisfy the above-described relationship, so that the central region Cn of the width-direction land portion 20 is satisfied. The rigidity in can be increased and the falling of the land portion 20 in the width direction can be suppressed. Thereby, since the fall of the contact area in the center area | region Cn of the width direction land part 20 can be suppressed, it becomes possible to improve wet performance. Further, since the groove area of the lateral groove 10 is formed so as to increase toward the outer region Sh, it is possible to increase the snow column shear force on the outer region Sh side, and improve the performance on snow. Is possible.

  In the present embodiment, when attention is paid to the groove width D10 of the lateral groove 10, the following relationship is satisfied. Specifically, as shown in FIG. 2, the groove width D10 of the inner groove end portion 10in on the innermost tread width direction Tw inside the central region Cn is defined as the groove width D10in, and the inner groove end portion on the outermost tread width direction Tw outer side of the central region Cn. A description will be given assuming that the groove width D10 of 10 inches is the groove width D10mid, and the groove width D10 of the outer groove end portion 10out on the outermost region Sh outer side in the tread width direction Tw is the groove width D10out.

  In the present embodiment, the maximum value of the groove width D10out of the lateral groove 10 in the outer region Sh is larger than the maximum value of the groove width D10in of the lateral groove 10 in the central region Cn. Here, as shown in FIG. 2, the maximum value of the groove width D10out of the lateral groove 10 in the outer region Sh is the groove width D10out at the outer groove end portion 10out of the lateral groove 10. On the other hand, the maximum value of the groove width D10in of the lateral groove 10 in the central region Cn is the groove width D10mid of the inner groove end portion 10in on the outermost side in the tread width direction Tw of the central region Cn (near the boundary between the central region Cn and the outer region Sh). is there. The groove width D10in at the inner groove end 10in of the lateral groove 10 is the narrowest. That is, the groove width D10 of the lateral groove 10 satisfies the relationship of groove width D10in <groove width Dmid <groove width D10out.

  Further, the groove width D10out at the outer groove end portion 10out of the outer region Sh is preferably 105% or more and 500% or less with respect to the groove width D10mid of the central region Cn. This is due to the following reason. When the groove width D10out of the outer region Sh is less than 105% with respect to the groove width D10mid of the central region Cn, there is a difference between the rigidity in the central region Cn of the width direction land portion 20 and the rigidity in the outer region Sh. This is because it cannot be found. On the other hand, when the groove width D10out is larger than 500% with respect to the groove width D10mid, the groove width D10out of the lateral groove 10 becomes too wide, and the ground contact area in the outer region Sh of the width direction land portion 20 decreases. It will pass. As a result, the surface friction force is deteriorated, and it is difficult to improve the performance on snow in the entire tire.

  Note that the groove width D10in, the groove width D10mid, and the groove width D10out preferably satisfy a proportional relationship according to the distance from the tire equatorial plane CL to the outside in the tread width direction Tw.

  Further, in the inner groove end portion 10in of the lateral groove 10, the angle θ10in formed by the extending direction of the lateral groove 10 and the tire circumferential direction Tc is equal to the extending direction of the lateral groove 10 and the tire circumferential direction Tc in the outer groove end portion 10out of the lateral groove 10. Is smaller than the angle θ10out formed.

  The angle θ10in at the inner groove end 10in of the lateral groove 10 is preferably within a range of 15 ° to 45 °. On the other hand, the angle θ10out at the outer groove end portion 10out of the lateral groove 10 is preferably in the range of 60 ° to 90 °. Moreover, it is preferable that the space | interval W10 in the tire circumferential direction Tc of the horizontal groove 10 is 20 mm or more and 60 mm or less.

(4) Configuration of Sipe A plurality of sipes 50 extending in a direction intersecting the direction in which the lateral groove 10 extends is formed in the width direction land portion 20. Here, in the present embodiment, the sipe has a groove width that can be closed when the width direction land portion 20 is grounded. Specifically, in the passenger car tire as in this embodiment, the sipe has a groove width of 1.0 mm or less. However, in a tire used for a large bus or truck such as a TBR tire, the sipe groove width may be 1.0 mm or more.

  In the present embodiment, each of the plurality of sipes 50 is formed in parallel. Further, it is assumed that the distance D50 between the plurality of sipes 50 is formed constant. Specifically, the plurality of sipes 50 include a sipe 50in formed in the central region Cn and a sipe 50out formed in the outer region Sh. In the present embodiment, the interval D50in between the sipes 50in formed in the central region Cn and the interval D50out between the sipes 50out formed in the outer region Sh are common. In addition, it is preferable that each space | interval of the sipe 50 is 4.0 mm or more and 6.0 mm or less.

  In the present embodiment, the angle θ50in formed by the extending direction of the sipe 50in formed in the central region Cn and the tread width direction Tw is 45 ° or less. The angle θ50in formed by the extending direction of the sipe 50in and the tread width direction Tw is more preferably in the range of 5 ° to 15 °. The angle θ50in formed between the extending direction of the sipe 50in formed in the central region Cn and the tread width direction Tw is the angle θ50out formed between the extending direction of the sipe 50out formed in the outer region Sh and the tread width direction Tw. It may be made smaller.

(5) Negative rate Next, the negative rate in the tread portion 2 will be described. In the present embodiment, the negative rate in the central region Cn is preferably in the range of 20 to 35%, and the negative rate in the outer region Sh is preferably in the range of 25 to 40%.

  By setting the negative rate as described above, in the central region Cn, the decrease in the contact area due to the decrease in the rigidity of the width direction land portion is suppressed, the decrease in wet performance is suppressed, and in the outer region Sh, By taking a lot of snow into the lateral groove, the snow column shear force can be increased and the performance on snow can be improved.

  The negative rate is the ratio of the groove area of all the grooves except the sipe 50 to the area of the entire ground plane. Specifically, the negative rate is a value obtained by dividing the total value of the groove area of the central circumferential narrow groove 31, the groove area of the lateral groove 10, and the groove area of the outer circumferential narrow groove 32 by the area of the entire ground contact surface. Is a value expressed as a percentage.

(6) Action / Effect According to the pneumatic tire 1 according to the present embodiment, in the tread portion 2, a plurality of circumferential narrow grooves 30 (the central circumferential narrow grooves 31 and the outer side) extend in the tire circumferential direction Tc in the central region Cn. It has a circumferential narrow groove 32). Further, according to the pneumatic tire 1, the lateral groove 10 extending in the tread width direction Tw is formed in the tread portion 2, and the width direction land portion 20 is formed by being partitioned by the lateral groove 10. A plurality of sipes 50 extending in a direction intersecting the direction in which the lateral groove 10 extends is formed in the width direction land portion 20. In the pneumatic tire 1, the groove area DSout of the lateral groove 10 in the outer region Sh is larger than the groove area DSin of the lateral groove 10 in the central region Cn.

  Here, as shown in FIG. 3, the friction coefficient on the road surface on snow is the compression resistance due to snow when the tire rotates, the surface frictional force on the surface of the land, the snow column shearing force of the groove, the corner of the land in the tire circumferential direction and It is enhanced by the edge effect of the corner formed by sipe.

  In the pneumatic tire 1 according to the present embodiment, since the sipe 50 is formed in the widthwise land portion 20, the edge effect can be enhanced and the performance on snow can be improved as compared with the case where the sipe 50 is not formed. .

  In the pneumatic tire 1 according to the present embodiment, a plurality of circumferential narrow grooves 30 (a central circumferential narrow groove 31 and an outer circumferential narrow groove 32) extending in the tire circumferential direction Tc are formed in the central region Cn. . Therefore, since the edge effect of the corner part formed in the width direction land part 20 by the circumferential narrow groove 30 can be ensured in the lateral direction input on the snowy road surface, the lateral grip on the snowy road surface can be ensured.

  Furthermore, in the pneumatic tire 1 according to the present embodiment, in the pneumatic tire 1, the groove area DSout of the lateral groove 10 in the outer region Sh is larger than the groove area DSin of the lateral groove 10 in the central region Cn. Therefore, it is possible to increase the snow entering the lateral groove 10 in the outer region Sh, increase the snow column shearing force in the outer region Sh, and ensure the grip in the front-rear direction on the snowy road surface.

  Although the plurality of circumferential narrow grooves 30 are formed in the central region Cn, the groove area DSin of the lateral groove 10 in the central region Cn is smaller than the groove area DSout of the lateral groove 10 in the outer region Sh. That is, in the pneumatic tire 1 according to the present embodiment, optimization of the negative rate in the central region Cn and the outer region Sh is achieved by optimizing the groove area DS of the lateral grooves 10 and the arrangement of the circumferential narrow grooves 30. Is planned. As a result, the surface frictional force is ensured by the optimum ground contact area in the central region Cn and the outer region Sh, and the longitudinal and lateral grips on the snowy road surface can be secured.

  Here, in the case of a general front wheel drive vehicle, the rear wheel load is smaller than the front wheel load. It is also known that improving the lateral force of the rear wheel leads to an increase in stability factor (steer characteristic), and as a result, the front / rear wheel balance of the vehicle is improved. In the pneumatic tire 1 according to the present embodiment, by arranging the circumferential narrow grooves 30 in a concentrated manner in the central region Cn, the lateral force is improved even in a rear wheel load with a small ground contact area, and the star on the road surface on snow is improved. The ability factor can be increased. Accordingly, in the pneumatic tire 1 according to the present embodiment, not only the lateral grip on the snow road surface but also the front / rear wheel balance on the snow road surface can be improved, so that the snow handling stability can also be improved. It becomes possible.

  Moreover, in the pneumatic tire 1 according to the present embodiment, since the plurality of circumferential narrow grooves 30 are formed in the central region Cn, drainage performance can be enhanced even on wet road surfaces, and wet performance can be improved. Further, since the groove area DSin of the lateral groove 10 in the central region Cn is smaller than the groove area DSout of the lateral groove 10 in the outer region Sh, the rigidity reduction of the width direction land portion 20 can be suppressed. It is possible to suppress a decrease in wet performance due to the above.

  As mentioned above, according to the pneumatic tire 1 which concerns on this embodiment, it becomes possible to make snow performance and wet performance compatible in a high dimension.

(7) Modification (7.1) Modification 1
Next, a modification according to this embodiment will be described. In the above-described embodiment, the case where the distance D50 of the sipe 50 is constant has been described as an example, but the present invention is not limited to this. In the present embodiment, the distance D50in between the sipes 50 formed in the central region Cn is narrower than the distance D50out between the sipes 50 formed in the outer region Sh. That is, the distance D50in between the sipes 50 formed in the central region Cn and the distance D50out between the sipes 50 formed in the outer region Sh satisfy the relationship D50in <D50out. The interval D50in is an average value of the intervals D50 of the sipes 50 in the region S20in in the central region Cn of the width direction land portion 20. The interval D50out is an average value of the intervals D50 of the sipes 50 formed in the region S20out of the outer region Sh of the width direction land portion 20.

  As described above, the distance D50 of the sipe 50 is formed so as to be narrower toward the inner side in the tread width direction Tw. The sipe interval D50in in the central region Cn is preferably 60% or more and 90% or less with respect to the sipe interval D50out in the outer region Sh. When the sipe interval D50in in the central region Cn is larger than 90% with respect to the sipe interval D50out in the outer region Sh, the rigidity in the central region Cn of the width direction land portion 20 and the rigidity in the outer region Sh The dominant difference cannot be found. On the other hand, when the sipe interval D50in is less than 60% of the sipe interval D50out, the block rigidity of the width direction land portion 20 in the central region Cn is extremely reduced, and the wet braking performance is deteriorated.

  The distance D50in between the sipes 50in formed in the central region Cn is 3.0 mm or more and 6.0 mm or less, and the interval D50out between the sipes 50out formed in the outer region Sh is 4.0 mm or more and 7.0 mm or less. Preferably there is. This is due to the following reason. If the distance D50in of the sipe 50in is smaller than 3.0 mm, the block rigidity of the land portion 20 in the width direction in the central region Cn is extremely lowered and the wet braking performance is deteriorated, and is larger than 6.0 mm. This is because the edge effect in the central region Cn of the land portion 20 in the width direction is reduced and the performance on snow is deteriorated. On the other hand, if the distance D50out of the sipe 50out formed in the outer region Sh is smaller than 4.0 mm, the block rigidity in the outer region Sh of the width direction land portion 20 is extremely lowered, and the wet braking performance is deteriorated. This is because, when it is larger than 7.0 mm, the edge effect in the outer region Sh of the width direction land portion 20 is lowered, and the performance on snow is deteriorated.

  Further, in the above-described example, the case where two types of the intervals of the sipe 50 are defined as the interval D50in and the interval D50out has been described as an example, but the intermediate region between the central region Cn and the outer region Sh is described. And the interval D50mid of the sipe 50 in the intermediate region may be used. In this case, the sipe 50 may be formed so as to satisfy the relationship of the distance D50in <the distance D50mid <the distance D50out. Further, in the case where a plurality of blocks are formed by being partitioned by the circumferential narrow grooves 30 in the width direction land portion 20, the sipe 50 formed in the block on the inner side of the tread width direction Tw is approximately the interval between the sipe 50. You may form so that D50 may become small. For example, the case where the center block, the second block, and the shoulder block are formed by the circumferential narrow groove 30 will be described as an example. In this case, the sipe 50 is set so as to satisfy the relationship “the distance D50 of the sipe 50 formed in the center block <the distance D50 of the sipe 50 formed in the second block <the distance D50 of the sipe 50 formed in the shoulder block”. It may be formed.

  Further, focusing on the density of the sipe 50 based on the above configuration, it can be said that the density Z50in of the sipe 50 in the central region Cn is higher than the density Z50out of the sipe 50 in the outer region Sh. That is, the relationship of density Z50in> density Z50out is satisfied.

  In the present embodiment, the density Z50in of the sipe 50 in the central region Cn is a value obtained by dividing the total length L50in of the sipe 50 formed in the central region Cn by the land area S20in in the central region Cn, and the density Z50in = L50in / Shown as S20in. On the other hand, the density Z50out of the sipe 50 in the outer region Sh is a value obtained by dividing the total length L50out of the sipe 50 formed in the outer region Sh by the land area S20out in the outer region Sh, and is expressed as density Z50out = L50out / S20out. It is.

  According to the present embodiment, the distance D50in between the sipes 50 formed in the central region Cn is narrower than the distance D50out between the sipes 50 formed in the outer region Sh. Here, when the pneumatic tire 1 is grounded, the ground contact length of the central region Cn is larger than the ground contact length of the outer region Sh. Therefore, according to the pneumatic tire according to the present embodiment, the distance D50in of the sipe 50 in the central region Cn is narrowed and the edge effect is efficiently increased, so the performance on snow can be improved.

(7.2) Modification 2
Next, Modification 2 according to the present embodiment will be described. FIG. 4 is a partial development view of the tread portion 2A of the pneumatic tire 1A according to the second modification of the present invention.

  As shown in the figure, the tread portion 2A may not have the central circumferential narrow groove 31 extending in the tire circumferential direction Tc in the central region Cn including the tire equatorial plane CL. That is, the pneumatic tire according to the present invention may be a tire in which a full lug pattern is formed. In the pneumatic tire 1 according to the present embodiment, the tread portion 2A has a circumferential land portion 100 extending in the tire circumferential direction Tc.

  The circumferential land portion 100 continues in the tire circumferential direction Tc within a range within 30% of the ground contact half width Wh from the tire equatorial plane CL. Here, in the example of FIG. 4, in the tread width direction Tw of the ground plane, a width W1 of 15% of the ground half width Wh and a width W2 of 30% of the ground half width Wh are shown.

  The circumferential narrow groove 30 is disposed within the range of the width W2 from the tire equatorial plane CL toward the outer side in the tread width direction Tw. In the circumferential narrow groove 30, at least a portion continuous in the tire circumferential direction Tc only needs to be disposed within the range of the width W2 from the tire equatorial plane CL toward the outer side of the tread width direction Tw.

  Further, the inner groove end portion 10in on the inner side in the tread width direction Tw of the lateral groove 10 is disposed within the range of the width W1 from the tire equatorial plane CL toward the outer side in the tread width direction Tw.

  In the pneumatic tire 1A as well, the on-snow performance and the wet performance can be achieved at a high level in the same manner as the pneumatic tire 1 according to the first embodiment.

(7.3) Modification 3
Next, Modification 2 according to the present embodiment will be described. In the pneumatic tire 1 according to the present embodiment, at least one of the plurality of sipes 50 is a three-dimensional sipe 50A (3D sipe). The formation ratio of the three-dimensional sipe 50A formed in the central region Cn is different from the formation ratio of the three-dimensional sipe 50A formed in the outer region Sh.

  FIG. 5A shows an example of a two-dimensional sipe 50x, and FIGS. 5B to 5G show an example of a three-dimensional sipe 50A.

  The “formation ratio of the three-dimensional sipe 50A formed in the central region Cn” indicates the ratio of the total length of the three-dimensional sipe 50A to the total length of the sipe 50 in the central region Cn in the tread surface view. On the other hand, the “formation ratio of the three-dimensional sipe 50A formed in the outer region Sh” indicates the ratio of the total length of the three-dimensional sipe 50A to the total length of the sipe 50 in the outer region Sh. For a sipe that is bent like the three-dimensional sipe 50A, the linear distance at both ends of the three-dimensional sipe 50A is defined as one length, and the total length of the three-dimensional sipe 50A is calculated.

  In the pneumatic tire 1 according to the present embodiment, the sipe 50 formed in the central region Cn among the plurality of sipe 50 is a three-dimensional sipe (3D sipe) 50A. Specifically, only the sipe 50 having both ends within the range of the central region Cn is a three-dimensional sipe 50A. That is, the sipe 50 formed in the outer region Sh is a two-dimensional sipe 50x. Therefore, in the pneumatic tire 1 according to the present embodiment, the formation ratio of the three-dimensional sipe 50A formed in the central region Cn is larger than the formation ratio of the three-dimensional sipe 50A formed in the outer region Sh. By using a three-dimensional sipe 50A as shown in FIGS. 5B to 5G as the sipe 50 in the central region Cn, the wall surfaces of the sipe 50A can support each other when the width direction land portion 20 is grounded. Since it can do, even if it is a case where the sipe space | interval D50in of the center area | region Cn is arrange | positioned narrowly, the fall of the rigidity of the width direction land part 20 can be suppressed.

  The groove walls of the three-dimensional sipe 50A formed in the width direction land portion 20 are arbitrarily bent at least in the tire radial direction so that they can support each other when the width direction land portion 20 inputs the tire circumferential direction Tc. It is desirable to have a different shape. Thereby, since the block rigidity in the tire circumferential direction Tc is increased, it is possible to increase the contact area and further improve the wet performance. Further, the groove walls of the three-dimensional sipe 50A have a shape that is arbitrarily bent with respect to the tread width direction Tw so that they can support each other at the time of input in the lateral direction (tread width direction Tw). Is desirable. As a result, since the lateral rigidity increases, it is possible to increase the ground contact area and improve the steering stability performance.

(7.4) Modification 4
Next, Modification 4 according to the present embodiment will be described. FIG. 6 is a partial development view of the tread portion 2B of the pneumatic tire 1B according to Modification 4 of the present invention. In the width direction land portion 20 according to the present embodiment, the one-side opening groove 60 having one end opened in the lateral groove 10 and the other end terminated in the width direction land portion 20 outside the circumferential narrow groove 30 in the tread width direction. Is formed.

  Here, the width direction land portion 20 has a stepping end 20A formed by the lateral groove 10 adjacent to the front of the tire rotation direction Tr and a kicking end 20B formed by the lateral groove 10 adjacent to the rear of the tire rotation direction Tr. doing. In the one-side opening groove 60, one end opens to the lateral groove 10 forming the kicking end 20 </ b> B, and the other end terminates in the width direction land portion 20. According to the one-side opening groove 60, water on the surface of the widthwise land portion 20 can be smoothly drained into the lateral groove 10 when the tire rotates.

  The groove width of the one-side opening groove 60 is formed so as to expand toward the lateral groove 10 on the side of the kick-out end 20B. According to the one-side opening groove 60, water on the surface of the width-direction land portion 20 can be efficiently drained into the lateral groove 10 along the tire rotation direction. Moreover, it is preferable that the extending direction of the one side opening groove 60 inclines with respect to the tire circumferential direction Tc. Specifically, the angle θ60 formed by the extending direction of the one-side opening groove 60 and the tire circumferential direction Tc is preferably 0 ° or more and 45 ° or less. This is due to the following reason. That is, if the inclination angle θ is greater than 45 degrees, the water drains from the flow of water in the ground contact surface and the drainage efficiency decreases.

  In the example of FIG. 6, the case where the one-side opening groove 60 is formed in the central region Cn is taken as an example, but the one-side opening groove 60 may also be formed in the outer region Sh. Further, the one side opening groove 60 may not be formed in the central region Cn but may be formed in the outer region Sh.

[Comparison evaluation]
Next, in order to further clarify the effects of the present invention, a comparative evaluation performed using pneumatic tires according to the following comparative examples and examples will be described. In addition, this invention is not limited at all by these examples.

(1) Configuration of each pneumatic tire First, in comparative evaluation, the pneumatic tire according to Comparative Example 1 (conventional product) to Comparative Example 2 and Examples (invention product) 1 to Example 8 (invention product). A pneumatic tire was prepared. The negative rate of each pneumatic tire was all 32%. The rim and the internal pressure were set so as to comply with the applicable rim and air pressure-load capacity correspondence table corresponding to the radial ply tire size defined in JATMA YEAR BOOK 2011. Each pneumatic tire had a lateral groove depth of 9 mm and a sipe depth of 6 mm.

  Table 1 shows the configuration of each pneumatic tire. Further, in the tires according to Examples 1 to 8 and Comparative Example 2, in common, the groove width D10out of the lateral groove 10 in the outer region Sh is set to be wider than the groove width D10in of the lateral groove 10 in the central region Cn. ing. That is, in the tires according to Examples 1 to 8 and Comparative Example 2, the groove area of the lateral groove 10 in the central region Cn is set to be smaller than the groove area of the lateral groove 10 in the outer region Sh.

  As the tires according to Examples 1 to 2 and Examples 5 to 7, tires on which the tread pattern shown in FIG. 1 was formed were used. Specifically, tires according to Examples 1 and 2 were formed with five circumferential narrow grooves formed in the central region. In addition, tires according to Example 1 and Examples 5 to 7 were used in which a two-dimensional (2D) sipe was formed in both the central region Cn and the outer region Sh. In the tire according to Example 2, a three-dimensional (3D) sipe is formed as the sipe 50 in the central region Cn, and a two-dimensional (2D) sipe is formed as the sipe 50 in the outer region Sh. Using.

  As the tires according to Examples 3 to 4, tires on which the tread pattern shown in FIG. 6 was formed were used. As the tires according to Examples 3 to 4, tires in which three circumferential narrow grooves were formed in the central region were used. In addition, tires according to Examples 3 to 4 used were formed with a one-sided opening groove. In addition, the tire according to Example 3 is a tire in which a two-dimensional (2D) sipe is formed in both the central region Cn and the outer region Sh. In the tire according to Example 4, a three-dimensional (3D) sipe is formed as the sipe 50 in the central region Cn, and a two-dimensional (2D) sipe is formed as the sipe 50 in the outer region Sh. Using.

  As the tire according to Example 8, the tire on which the tread pattern shown in FIG. 4 was formed was used. In the tire according to Example 8, a tire in which the inner groove end portion 10in of the lateral groove 10 is located at 15% of the ground contact half width Wh in the tread width direction from the tire equator line CL was used. As the tire according to Example 8, a tire in which a two-dimensional (2D) sipe is formed in both the central region Cn and the outer region Sh was used.

  FIG. 7 is a partial development view of the tread portion of the tire according to Comparative Example 1. As the tire according to the comparative example, a tire in which the groove width D10 of the lateral groove is formed with a constant width in the central region Cn and the outer region Sh was used. The tire according to the comparative example used a tire in which a three-dimensional (3D) sipe is not formed and a two-dimensional (2D) sipe is formed. Also in Comparative Example 1, the lateral groove is formed from the tire equatorial plane CL to each tread end. Such a configuration is the same as that of the first to eighth embodiments.

  As the tire according to Comparative Example 2, a tire in which the tread pattern shown in FIG. 4 was formed was used. In the tire according to Comparative Example 2, a tire in which the inner groove end portion 10in of the lateral groove 10 is located at 20% of the ground contact half width Wh in the tread width direction from the tire equator line CL was used. As the tire according to Example 8, a tire in which a two-dimensional (2D) sipe is formed in both the central region Cn and the outer region Sh was used.

  As shown in Table 1, in the tire in which the central circumferential narrow groove is formed on the tire equatorial plane CL and the lateral groove communicates with the central circumferential narrow groove, the inner groove end portion 10in extends in the tread width direction from the tire equator line CL. The tire is located at 0% of the ground contact half width Wh.

(2) Test method and evaluation result The test performed the performance test on snow and the wet performance test. As the performance test on snow, an acceleration performance test and a steering stability test on the road surface on snow were performed. Specifically, in the acceleration performance test, the time (acceleration time) until the accelerator was fully opened from a stationary state and traveled for 50 m was measured, and the measurement result was evaluated. In the snow handling stability test, the evaluation driver measured the lap time when the evaluation course was run and evaluated the measurement results. In the wet performance test, we prepared a pool-like wet road surface with a water depth of 2 mm on the paved road surface, and applied the full brake while driving on this road surface at a speed of 60 km / h to measure the braking distance to complete rest. The results were evaluated.

  The data relating to the pneumatic tire used in the test are “tire size: 195 / 65R15”, “rim wheel size: 6J-15”, “internal pressure: internal pressure 200 kPa”, “vehicle: passenger car”, “load: adult” The measurement was performed according to the conditions of "one male ride".

The evaluation results are shown in Table 1. In addition, the evaluation result shown in Table 1 is shown by the index | exponent which used the result of the comparative example 1 as the reference | standard (100), and represents that it is so excellent that the value of an index | exponent is large.

  As shown in Table 1, it can be seen that the pneumatic tires according to Examples 1 to 8 are superior in snow performance and wet performance as compared with the pneumatic tires according to Comparative Examples 1 and 2. Therefore, according to the pneumatic tire of this invention, it was proved that the effect which can make snow performance and wet performance compatible in a high dimension is large.

[Other Embodiments]
Although the contents of the present invention have been disclosed through the embodiments of the present invention as described above, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operational techniques will be apparent to those skilled in the art.

  In the embodiment described above, the circumferential narrow groove 30 is formed only in the range of the central region Cn, but may be formed also in the outer region Sh.

  Further, in the embodiment described above, the central circumferential narrow groove 31 extending along the tire equatorial plane CL is formed as the circumferential narrow groove 30, but the central circumferential narrow groove 31 is not necessarily required. The central circumferential narrow groove 31 may not be provided. In this case, it is possible to form a circumferential land portion extending continuously on the tire equatorial plane CL.

  In the above-described embodiment, when the block defined by the circumferential narrow groove 30 and the lateral groove 10 is formed in the widthwise land portion 20, the block formed by the circumferential narrow groove 30 and the lateral groove 10. The tip portion has an acute angle in the tread surface view. In this case, the rigidity at the tip portion of the block may be extremely reduced. In view of such a case, a bottom raised portion may be provided at the groove bottom at a portion where the circumferential narrow groove 30 and the lateral groove 10 intersect. In this case, since the rigidity fall in the front-end | tip part of a block can be suppressed, the fall on snow performance and wet performance can be suppressed.

  Further, the above-described embodiments and modifications can be combined. As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is determined only by the invention specifying matters according to the scope of claims reasonable from the above description.

CL: tire equatorial plane, Cn: central region, D10: groove width, D50: spacing, Sh: outer region, TE: ground contact edge, Tc: tire circumferential direction, Tr: tire rotation direction, Tw: tread width direction, 1 , 1A, 1B ... tire, 2, 2A, 2B ... tread portion, 10 ... lateral groove, 10in ... inner groove end portion, 10out ... outer groove end portion, 20 ... width direction land portion, 30 ... circumferential narrow groove, 31 ... central circumference Directional narrow groove, 32 ... outer circumferential narrow groove, 50 ... sipe, 50A ... three-dimensional sipe, 60 ... one side open groove, 100 ... circumferential land portion

Claims (5)

A tread portion having a ground contact surface that contacts a road surface is a tire including a lateral groove extending in a tread width direction and a width direction land portion partitioned by forming a plurality of the lateral grooves at intervals in the tire circumferential direction. And
The outer groove end portion on the outer side in the tread width direction of the lateral groove is disposed so as to reach the ground contact end portion on the outer side in the tread width direction of the ground contact surface,
The inner groove end portion on the inner side in the tread width direction of the lateral groove is arranged within a range of 15% or less of the ground contact half width from the tire equator surface, when the ground half width is from the tire equator surface to the ground contact end portion. And
The tread portion is formed with a plurality of circumferential narrow grooves extending continuously in the tire circumferential direction,
In the width direction land portion, a plurality of sipes extending in a direction intersecting the direction in which the lateral groove extends is formed,
The tread portion includes a central region that is closest to the tire equator surface and is located outside the central region in the tread width direction, among regions determined by equally dividing a region from the tire equator surface to the ground contact edge. An outer region located,
The plurality of circumferential narrow grooves are disposed in the central region,
Groove area of the lateral grooves in the outer region is much larger than the groove area of the lateral grooves in the central region,
The tread portion has a circumferential land portion extending in the tire circumferential direction,
The tire according to claim 1, wherein the circumferential land portion is continuous in the tire circumferential direction within a range within 30% of the ground contact half width from the tire equator plane . The distance of the sipes formed in the central region, tire according to claim 1, characterized in that narrower than the distance between the sipes formed in the outer region. The tire according to claim 1 or 2 , wherein an angle formed by an extending direction of the sipe formed in the central region and a tread width direction is 45 ° or less. Of the plurality of sipes, at least one or more sipes are three-dimensional sipes,
And formation ratio of the three-dimensional sipe which is formed in the central region, wherein the formation rate of the three-dimensional sipe which is formed in the outer region, different in any one of claims 1 to 3, wherein The described tire. The width direction land portion is formed with a one-side opening groove having one end opened in the lateral groove and the other end terminated in the width direction land portion outside the circumferential narrow groove in the tread width direction. The tire according to any one of claims 1 to 4 , characterized in that:

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