JP6946923B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

For all-season tires, not only performance when driving on snowy roads but also performance when driving on dry roads is required. Conventionally, tires have been known for the purpose of achieving both performance on snow and steering stability on a dry road surface (Patent Document 1).
In the tire of Patent Document 1, five land portions extending in the tire circumferential direction are formed on the tread surface of the tread portion by four circumferential main grooves extending along the tire circumferential direction. The section consists of a center land area, a middle land area, and a shoulder land area. In the tire of Patent Document 1, it is said that by forming lug grooves and sipes that intersect with respect to the tire circumferential direction in each land portion, it is possible to obtain drainage and snow removal performance on snow. ing. Further, in the tire of Patent Document 1, in the middle land portion, one end of the lug groove opens in the circumferential main groove and the other end ends in the middle land portion, and one end of the lug groove is the circumferential main groove. A second sub-groove that opens into the groove and the other end ends in the middle land, and one end of the sipe opens at the end of the lug groove and the other end ends in the middle land. By having them independently, the middle land part is configured as a rib that is continuous in the tire circumferential direction, the rigidity of the middle land part becomes high, and it is possible to obtain dry road steering stability performance, and as a result, snow performance and dry road performance. It is said that it is possible to achieve both steering stability performance.

Japanese Patent No. 5765492

Snow roads include icy roads covered with compacted icy snow and icy icy roads covered with uncompacted icy snow. The tire of Patent Document 1 has insufficient steering stability in the presence of such various snow road surfaces.
Further, in all-season tires, it is required that the generation of noise during running can be suppressed, that is, the noise performance is good, as the performance when running on a dry road surface. In a tire provided with a lug groove, the air column resonance sound generated in the main groove in the circumferential direction during traveling may be emitted toward the outside of the vehicle, and the noise outside the vehicle may increase.

An object of the present invention is to provide a pneumatic tire capable of achieving both snow performance and noise performance.

One aspect of the present invention is a pneumatic tire provided with a tread pattern on the tread portion.
The tread pattern is
On one side of the tire center line in the tire width direction, the shoulder side main groove and the center side main groove, which are arranged at intervals from each other and extend in the tire circumferential direction,
In the shoulder land region located outside the shoulder side main groove in the tire width direction, a plurality of first first portions extending from the outside in the tire width direction toward the shoulder side main groove and arranged at intervals in the tire circumferential direction. With a lug groove
In the middle land area sandwiched between the shoulder side main groove and the center side main groove, the side of the shoulder side main groove along the direction in which the first lug groove extends so as to cross the shoulder side main groove. A plurality of second lug grooves extending from the center side to the main groove, closing in the middle land area, and arranged at intervals in the tire circumferential direction.
In the middle land region, a plurality of first sipes extending from the closed end of the second lug groove toward the center side main groove and arranged at intervals in the tire circumferential direction,
The center side main groove is located inside the center side main groove in the tire width direction, and in the center land area passing through the tire center line, the center side main groove is extended along the direction in which the first sipe extends so as to cross the center side main groove. A plurality of third lug grooves extending from the groove side so as to move away from the center side main groove, closing in the center land area, and arranged at intervals in the tire circumferential direction are provided.
The first lug groove, the second lug groove, the first sipe, and the third lug groove extend so as to form a plurality of extension lines spaced apart from each other in the tire circumferential direction. death,
The tread pattern further extends the tire circumferential region between the adjacent extension lines from the center side main groove side toward the shoulder side main groove in the middle land portion region, and the middle land portion. It is characterized in that it is closed in the region and includes a plurality of fourth lug grooves arranged at intervals in the tire circumferential direction.

Further, in the middle land region, the tire circumferential region extends from the closed end of the fourth lug groove toward the shoulder side main groove so as to extend the tire circumferential region between adjacent extension lines, and is spaced in the tire circumferential direction. It is preferable to have a plurality of second sipes arranged apart from each other.

Further, in the shoulder land region, the shoulder side main along the direction in which the second sipe extends so as to extend the tire circumferential region between the adjacent extension lines and across the shoulder side main groove. It is preferable to include a plurality of third sipes extending outward in the tire width direction from the groove side and alternately arranged with the first lug groove at intervals in the tire circumferential direction.

Further, in the middle land region, the tire circumferential region between the second lug groove and the fourth lug groove in the tire circumferential direction is defined as the center side main groove from the shoulder side main groove side. It is preferable to have a plurality of fourth sipes extending to the side and arranged at intervals in the tire circumferential direction.

Further, in the shoulder land region, the tread portion extends from a position away from the shoulder side main groove to the outside in the tire width direction of the ground contact end of the tread portion so as to extend the tire circumferential region between adjacent extension lines. It is preferable to provide a plurality of fifth lug grooves arranged at intervals in the tire circumferential direction.

It is preferable that the end portion of the first lug groove on the outer side in the tire width direction is closed on the inner side of the ground contact end of the tread portion in the tire width direction.

Further, in the shoulder land region, a plurality of fifth sipes extending outward in the tire width direction along the extension line from the closed end of the first lug groove and arranged at intervals in the tire circumferential direction. It is preferable to provide.

It is preferable that the range in the tire width direction in which the second lug groove is located and the range in the tire width direction in which the fourth lug groove is located partially overlap.

The inclination angles of the second lug groove, the third lug groove, and the fourth lug groove with respect to the tire circumferential direction are preferably 50 ° to 90 °.

Further, in the center land region, a plurality of sixth sipes are arranged at intervals in the tire circumferential direction, extending along the extending direction of the fourth lug groove so as to cross the center side main groove. It is preferable to provide.

Further, in the center land region, the tire circumferential region between the third lug groove and the sixth sipe is extended from the side of the center side main groove so as to be away from the center side main groove. It is preferable to have a plurality of seventh sipes arranged at intervals in the tire circumferential direction.

Further, in the shoulder land region, the tread portion extends from a position away from the shoulder side main groove to the outside in the tire width direction of the ground contact end of the tread portion so as to extend the tire circumferential region between adjacent extension lines. A plurality of fifth lug grooves arranged at intervals in the tire circumferential direction,
In the shoulder land region, the tire circumferential region between the first lug groove and the fifth lug groove in the tire circumferential direction extends from the shoulder side main groove side to the outside in the tire width direction to extend the tire. It is preferable to include eighth sipes arranged at intervals in the circumferential direction.

According to the present invention, a pneumatic tire capable of achieving both snow performance and noise performance can be obtained.

It is an external perspective view which shows an example of the pneumatic tire of this embodiment. It is a figure which shows an example of the profile cross section of the pneumatic tire of this embodiment. It is a figure which shows an example of the tread pattern of the tire of FIG.

(Overall explanation of tires)
Hereinafter, the pneumatic tire of the present invention will be described. FIG. 1 is an external perspective view showing a pneumatic tire (hereinafter, referred to as a tire) 10 of the present embodiment. FIG. 2 is a tire cross-sectional view showing a cross section of the tire 10.
The tire 10 is, for example, a passenger car tire. Passenger car tires are tires specified in Chapter A of JATMA YEAR BOOK 2012 (Japan Automobile Tire Association Standards). In addition, the tire 10 can be applied to the tires for light trucks specified in Chapter B and the tires for trucks and buses specified in Chapter C.

The tire width direction is a direction parallel to the rotation axis of the tire. The outside in the tire width direction is the side away from the tire center line CL (see FIG. 2) representing the tire equatorial plane in the tire width direction. Further, the inside in the tire width direction is the side approaching the tire center line CL in the tire width direction. The tire circumferential direction is a direction in which the tire rotates about the rotation axis of the tire as the center of rotation. The tire radial direction is a direction orthogonal to the rotation axis of the tire. The outer side in the tire radial direction refers to the side away from the rotation axis. Further, the inside in the radial direction of the tire means a side approaching the rotation axis.

(Tire structure)
FIG. 2 is a profile cross-sectional view of the tire 10 of the present embodiment. The tire 10 includes a tread portion 10T having a tread pattern, a pair of bead portions 10B, and a pair of side portions 10S provided on both sides of the tread portion 10T and connected to the pair of bead portions 10B and the tread portion 10T. Be prepared.
The tire 10 has a carcass ply 12, a belt 14, and a bead core 16 as skeleton materials, and around these skeleton materials, a tread rubber member 18, a side rubber member 20, a bead filler rubber member 22, and so on. It mainly has a rim cushion rubber member 24 and an inner liner rubber member 26.

The carcass ply 12 is made of a carcass ply material in which organic fibers are coated with rubber, which is wound around a pair of annular bead cores 16 to form a toroidal shape. The carcass ply 12 is wound around the bead core 16 and extends outward in the tire radial direction. A belt 14 composed of two belt materials 14a and 14b is provided on the outer side of the carcass ply 12 in the tire radial direction. The belt 14 is composed of a member coated with rubber on a steel cord arranged at a predetermined angle, for example, 20 to 30 degrees with respect to the tire circumferential direction, and the lower belt material 14a is attached to the upper belt material 14b. The width in the tire width direction is longer than that. The inclination directions of the steel cords of the two-layer belt members 14a and 14b are opposite to each other. Therefore, the belt materials 14a and 14b are interlaced layers, and suppress the expansion of the carcass ply 12 due to the filled air pressure.

A tread rubber member 18 is provided on the outer side of the belt 14 in the tire radial direction, and side rubber members 20 are connected to both ends of the tread rubber member 18 to form a side portion 10S. A rim cushion rubber member 24 is provided at the inner end of the side rubber member 20 in the tire radial direction and comes into contact with the rim on which the tire 10 is mounted. On the outer side of the bead core 16 in the tire radial direction, it is sandwiched between the part of the carcass ply 12 before being wound around the bead core 16 and the part of the carcass ply 12 wound around the bead core 16. A bead filler rubber member 22 is provided. An inner liner rubber member 26 is provided on the inner surface of the tire 10 facing the air-filled tire cavity region surrounded by the tire 10 and the rim.
In addition, between the belt material 14b and the tread rubber member 18, a two-layer belt cover 30 covered with rubber of organic fibers is provided so as to cover the belt 14 from the outer side in the tire radial direction of the belt 14.

(Tread pattern)
FIG. 3 is a diagram showing an example of the tread pattern of the tire 10 of FIG.

The tread pattern includes a shoulder side main groove 32, a center side main groove 34, a plurality of first lug grooves 52, a plurality of second lug grooves 54, a plurality of first sipes 56, and a plurality of first lug grooves. A lug groove 58 of 3 and a plurality of fourth lug grooves 66 are provided.

The shoulder-side main groove 32 and the center-side main groove 34 are grooves that are arranged on one side (left side in FIG. 3) in the tire width direction with respect to the tire center line CL at intervals and extend in the tire circumferential direction. be. The tire 10 having the tread pattern shown in FIG. 3 is mounted so that one side in the tire width direction faces the inside (inside) of the vehicle with respect to the tire center line CL, but the other side in the tire width direction is It may be mounted so as to face the outside (out side) of the vehicle.

The first lug groove 52 extends from the outside in the tire width direction toward the shoulder side main groove 32 in the shoulder land area 42 located outside the shoulder side main groove 32 in the tire width direction, and is spaced apart in the tire circumferential direction. Are arranged. In the example shown in FIG. 3, the first lug groove 52 is bent in the middle of the extending direction, and is inclined with respect to the tire width direction with the outer portion 52a extending in the direction parallel to the tire width direction. It has an inner portion 52b that extends in the direction of the tire. In the example shown in FIG. 3, the bending position of the first lug groove 52 is the position in the tire width direction through which the shoulder narrow groove 31 described later passes.

The second lug groove 54 is formed in the middle land region 44 sandwiched between the shoulder side main groove 32 and the center side main groove 34 in the direction in which the first lug groove 52 extends so as to cross the shoulder side main groove 32. Along the shoulder side main groove 32, it extends toward the center side main groove 34 and closes in the middle land area 44, and is arranged at intervals in the tire circumferential direction. The direction in which the first lug groove 52 extends so as to cross the shoulder side main groove 32 means the extending direction of the end portion of the first lug groove 52 on the shoulder side main groove 32 side, and is shown in FIG. In the example, it is the extending direction of the inner portion 52b of the first lug groove 52. By extending the second lug groove 54 in this way, the first lug groove 52 and the second lug groove 54 form one long lug groove extending across the shoulder side main groove 32. This long lug groove has a large groove volume, and a large snow column shearing force can be obtained. Therefore, steering stability is improved on a fresh snowy road surface. On the other hand, in the region in the tire circumferential direction between the long lug grooves adjacent to each other in the tire circumferential direction, the ground contact area is large and the frictional force with the road surface is secured, so that the steering stability is improved on the snow-packed road surface. In the present specification, the snow-packed road surface includes an icy road surface.

The first sipe 56 extends from the closed end of the second lug groove 54 toward the center side main groove 34 in the middle land region 44, and is arranged at intervals in the tire circumferential direction. Therefore, the middle land portion is easily deformed, and the effect of the second lug groove 54 compacting the snow column is increased. In the example shown in FIG. 3, the first sipe 56 extends along the extending direction of the inner portion 52b of the first lug groove 52.

The third lug groove 58 is located inside the center side main groove 34 in the tire width direction, and the first sipe 56 crosses the center side main groove 34 in the center land area 46 passing through the tire center line CL. It extends from the side of the center side main groove 34 along the extended direction so as to move away from the center side main groove 34, closes in the center land area 46, and is arranged at intervals in the tire circumferential direction. The direction in which the first sipe 56 extends so as to cross the center-side main groove 34 is a direction substantially equal to the direction along the extending direction of the inner portion 52b of the first lug groove 52 in the example shown in FIG. Is. As described above, since the first sipe 56 faces the third lug groove 58 with the center side main groove 34 interposed therebetween, the other lug grooves face each other with the center side main groove 34 interposed therebetween. The groove volume in the direction intersecting the center side main groove 34 is smaller than that in the case where the air column resonance sound is reduced. Since the ground pressure is high in the region near the center-side main groove 34 and the air column resonance sound tends to be loud, the vehicle exterior noise can be effectively reduced by arranging the third lug groove 58 in this way. Further, since the snow column shearing force is obtained by the third lug groove 58, the steering stability on a fresh snow road surface is improved.

The first lug groove 52, the second lug groove 54, the first sipe 56, and the third lug groove 58 form a plurality of first extension lines 80 spaced apart from each other in the tire circumferential direction. It is extended like this. The first extension line 80 crosses the shoulder side main groove 32 and the center side main groove 34, and has a first lug groove 52, a second lug groove 54, a first sipe 56, and a third lug groove 58. , In this order, are virtual lines that extend to connect to each other. In the tread pattern of the tire 10, when traveling along the first extension line 80, low-rigidity portions and high-rigidity portions appear alternately in the land region. The portion having low rigidity is specifically a portion in the tire width direction region where the lug groove extends, and as described above, steering stability on a fresh snow road surface is improved. On the other hand, the highly rigid portion is specifically a portion in the tire width direction region where the sipes extend, and as described above, the steering stability on a snow-packed road surface is improved. In this way, when traveling along the first extension line 80 in the land area, the portion where the steering stability is improved on the fresh snow road surface and the portion where the steering stability is improved on the snow-packed road surface appear alternately. With the tire 10, the steering stability on a fresh snowy road surface and the steering stability on a snow-packed road surface are exhibited in a well-balanced manner.

The first extension line 80 may be bent or curved to extend in the middle of the extending direction. When bent or curved in the middle, the angle difference in the extending direction before and after the bent or curved portion is 30 degrees or less. In the example shown in FIG. 3, the first extension line 80 extends in a direction parallel to the tire width direction at the outer portion in the tire width direction with the shoulder narrow groove 31 as a boundary, and the inner portion in the tire width direction is the tire. It is tilted by, for example, 10 ° to 25 ° with respect to the width direction.
The shoulder narrow groove 31 is a groove that is arranged at a distance from the shoulder side main groove 32 in the shoulder land area 42, is narrower than the groove width of the shoulder side main groove 32, and extends in the tire circumferential direction. The shoulder narrow groove 31 makes it easy to deform the land portion of the shoulder and improves the snow performance by the edge effect on the lateral force.

The fourth lug groove 66 extends the tire circumferential region between the adjacent first extension lines 80 from the side of the center side main groove 34 toward the shoulder side main groove 32 in the middle land region 44. It is closed in the middle land area 44 and is arranged at intervals in the tire circumferential direction. Since the end of the fourth lug groove 66 on the center side main groove 34 side is located at a position different from the end of the third lug groove 58 on the center side main groove 34 side in the tire circumferential direction, it is on the center side. The groove volume in the direction intersecting the main groove 34 is small, and the air column resonance sound is reduced. Therefore, the noise outside the vehicle is reduced and the noise performance is excellent. Further, since the snow column shearing force is obtained by the fourth lug groove 66, the steering stability on a fresh snow road surface is improved. In the tread pattern of the tire 10, the fourth lug groove 66 is provided in the tire circumferential direction region between the first extension lines 80 adjacent to each other in the tire circumferential direction, so that in the land region, the tire circumferential direction is also formed. Low-rigidity and high-rigidity parts of the land tend to appear alternately, and when traveling along the tire circumferential direction at the same tire width direction position, the part where steering stability is improved on a fresh snow road surface and the part on a snow-packed road surface Parts that improve steering stability tend to appear alternately. Therefore, according to the tire 10, in the direction along the first extension line 80 and the direction along the tire circumferential direction, in the land region, the portion where the steering stability on the fresh snow road surface is improved, and the snow-packed road surface. By alternating the parts that improve the steering stability, the steering stability on the fresh snow road surface and the steering stability on the compressed snow road surface are exhibited in a well-balanced manner. Therefore, it is excellent in steering stability (hereinafter, also referred to as snow performance) in the presence of various snow road surfaces.
The fourth lug groove 66 extends so as to form a plurality of second extension lines 90 spaced apart from each other in the tire circumferential direction. The second extension line 90 is formed alternately with the first extension line 80 in the tire circumferential direction. The second extension line 90 is, for example, at least one of a fourth lug groove 66, a second sipe 64, a third sipe 62, a fifth lug groove 60, and a sixth sipe 68, which will be described later. It may be formed together with one. The second extension line 90 may be bent or curved to extend in the middle of the extending direction. When bent or curved in the middle, the angle difference in the extending direction before and after the bent or curved portion is 30 degrees or less.

According to one embodiment, it is preferable to further include a plurality of second sipes 64. The second sipe 64 is directed from the closed end of the fourth lug groove 66 toward the shoulder side main groove 32 so as to extend the tire circumferential region between the adjacent first extension lines 80 in the middle land region 44. It extends and is arranged at intervals in the tire circumferential direction. Since the second sipe 64 is provided, the middle land portion is easily deformed, and the effect of the fourth lug groove 66 compacting the snow column is increased. Further, in the land area, the high-rigidity portion and the low-rigidity portion are likely to appear alternately in the direction along the second extension line 90 and in the tire circumferential direction, and the steering stability on the fresh snow road surface and the snow-packed road surface is more well-balanced. It will be demonstrated.
In this case, the tread pattern preferably further comprises a plurality of third sipes 62. In the third sipe 62, the second sipe 64 is extended across the shoulder side main groove 32 so as to extend the tire circumferential region between the adjacent first extension lines 80 in the shoulder land region 42. It extends outward in the tire width direction from the side of the shoulder side main groove 32 along the direction, and is alternately arranged with the first lug groove 52 at intervals in the tire circumferential direction. The direction in which the second sipe 64 extends so as to cross the shoulder-side main groove 32 is the direction along the extending direction of the inner portion 52b of the first lug groove 52 described above in the example shown in FIG. The directions are almost parallel. As described above, the second sipe 64 and the third sipe 62 are provided in the area in the tire circumferential direction between the first lug groove 52 and the second lug groove 54 adjacent to each other in the tire circumferential direction. As a result, the ground contact area is large and the frictional force with the road surface is secured. Further, by providing the third sipe 62, the rigidity of the land portion between the closed end of the fifth lug groove 60 and the shoulder side main groove 32 is reduced, and the hitting sound generated by the collision with the road surface is generated. It will be reduced. As a result, noise outside the vehicle is reduced.

According to one embodiment, the tread pattern preferably further comprises a plurality of fourth sipes 74. The fourth sipe 74 sets a tire circumferential region between the second lug groove 54 and the fourth lug groove 66 in the middle land region 44 from the side of the shoulder side main groove 32 to the center side main groove 34. It extends to the side of the tire and is arranged at intervals in the tire circumferential direction. The fourth sipe 74 divides the movement of the land portion surrounding the second lug groove 54 and the land portion surrounding the fourth lug groove 66, and the lug grooves 54 and 66 respectively form a snow column. The effect of hardening increases.

According to one embodiment, the tread pattern preferably further comprises a plurality of fifth lug grooves 60. The fifth lug groove 60 is located on the ground contact end 10a of the tread portion 10T from a position away from the shoulder side main groove 32 so as to extend the tire circumferential region between the adjacent extension lines 80 in the shoulder land region 42. It extends to the outside in the tire width direction and is arranged at intervals in the tire circumferential direction. In the example shown in FIG. 3, the fifth lug groove 60 extends outward from the shoulder narrow groove 31 in the tire width direction.
The ground contact ends 10a and 10b are both ends of the ground contact surface in the tire width direction when the tire 10 is assembled to the regular rim, the regular internal pressure is applied, and the ground contact surface is grounded on a horizontal plane under the condition that 88% of the regular load is the load load. .. The regular rim means the "measurement rim" specified in JATMA, the "Design Rim" specified in TRA, or the "Measuring Rim" specified in ETRTO. The normal internal pressure means the "maximum air pressure" specified in JATMA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified in TRA, or the "INFLATION PRESSURES" specified in ETRTO. The normal load means the "maximum load capacity" specified in JATMA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified in TRA, or the "LOAD CAPACITY" specified in ETRTO.
The fifth lug groove 60 does not communicate with the main groove 32 on the shoulder side and is closed in the shoulder land region 42, so that the air column resonance sound is suppressed and the ground contact end 10a extends to the outside in the tire width direction. By extending, the steering stability on the fresh snow road surface due to the shearing force of the snow column is improved in the shoulder area where the load is large.

According to one embodiment, it is preferable that the outer end portion of the first lug groove 52 in the tire width direction is closed inside the ground contact end 10a of the tread portion 10T in the tire width direction. As a result, the air column resonance sound generated by the first lug groove 52 is reduced, and the noise outside the vehicle is suppressed.
In this case, the tread pattern preferably further comprises a plurality of fifth sipes 50. The fifth sipe 50 extends outward in the tire width direction along the first extension line 80 from the closed end of the first lug groove 52 in the shoulder land region 42, and is arranged at intervals in the tire circumferential direction. Has been done. Since the fifth sipe 50 is provided, the land portion of the shoulder is easily deformed, and the effect of the first lug groove 52 compacting the snow column is increased.

According to one embodiment, it is preferable that the range in the tire width direction in which the second lug groove 54 is located and the range in the tire width direction in which the fourth lug groove 66 is located partially overlap. Since the extending regions of the second lug grooves 54 and the fourth lug grooves 66 alternately arranged in the tire circumferential direction overlap in the tire width direction, the central portion in the tire width direction of the middle land portion The rigidity can be appropriately lowered, and the effect of each of the second lug groove 54 and the fourth lug groove 66 solidifying the snow column is improved.

The inclination angles of the second lug groove 54, the third lug groove 58, and the fourth lug groove 66 with respect to the tire circumferential direction are preferably 50 ° to 90 °. If the inclination angle is less than 50 °, a sufficient snow column shearing force may not be obtained during control drive. The inclination angle is more preferably 65 ° to 80 °. As a result, the balance of snow performance during control drive and turning is improved.

According to one embodiment, it is preferable to further include a plurality of sixth sipes 68. The sixth sipe 68 extends in the center land region 46 along the direction in which the fourth lug groove 66 extends so as to cross the center side main groove 34, and is arranged at intervals in the tire circumferential direction. .. By providing the sixth sipe 68, the movement of the land portion surrounding the third lug groove 58 adjacent to each other in the tire circumferential direction is divided, and the effect of the third lug groove 58 solidifying the snow column. Will increase. Further, the contact area of the tire circumferential direction region between the third lug grooves 58 adjacent to each other in the tire circumferential direction is increased, the frictional force with the road surface is secured, and the steering stability is improved on the snow-packed road surface.
In this case, the tread pattern preferably further comprises a plurality of seventh sipes 76. The seventh sipe 76 determines the tire circumferential region between the third lug groove 58 and the sixth sipe 68 in the center land region 46 from the side of the center side main groove 34 and from the center side main groove 34. It extends away and is spaced apart in the tire circumferential direction. The seventh sipe 76 enhances the effect of dividing the movement of the land portion surrounding the third lug groove 58, and further enhances the effect of the third lug groove solidifying the snow column.

According to one embodiment, the tread pattern preferably includes an eighth sipe 72 when the tread pattern includes a plurality of fifth lug grooves 60. The eighth sipe 72 sets the tire circumferential region between the first lug groove 52 and the fifth lug groove 60 in the tire circumferential direction in the shoulder land region 42 from the side of the shoulder side main groove 32. It extends outward in the width direction and is arranged at intervals in the tire circumferential direction. Since the eighth sipe 72 is provided, the movement of the land portion surrounding the first lug groove 52 and the land portion surrounding the fifth lug groove 60 is separated, and the movement of the land portion surrounding the fifth lug groove 60 is separated, so that the first lug groove The effect of the 52 solidifying the snow column and the snow drainage property of the fifth lug groove 60 are increased.
In the example shown in FIG. 3, the eighth sipe 72 extends outward in the tire width direction across the shoulder narrow groove 31 and extends to the outside in the tire width direction of the ground contact end 10a described later.

In the tire 10 of the present embodiment, in the direction along the first extension line 80 and the direction along the tire circumferential direction, in the land region, a portion where steering stability is improved on a fresh snow road surface and a snow-packed road surface. By alternating the parts that improve the steering stability, the steering stability on the fresh snow road surface and the steering stability on the compressed snow road surface are exhibited in a well-balanced manner. Therefore, it has excellent snow performance. Further, in the tire 10 of the present embodiment, since the first sipe 56 faces the third lug groove 58 with the center side main groove 34 interposed therebetween, the air column resonance sound is reduced and the noise outside the vehicle is reduced. Is effectively reduced. Such a tire 10 is preferably used as an all-season tire.

In the tread pattern shown in FIG. 3, the first lug groove 52 and the second lug groove 54 are opened in the shoulder side main groove 32, and the third lug groove 58 and the fourth lug groove 66 are centered. It is open to the side main groove 34. Further, in the tread pattern shown in FIG. 3, the first sipe 56 and the seventh sipe 76 are opened in the center side main groove 34, and the second sipe 64 and the third sipe 62 are the shoulder side main groove 32. The fourth sipe 74 opens into both the shoulder-side main groove 32 and the center-side main groove 34, and the sixth sipe 68 and the eighth sipe 72 are the center-side main groove 34 and the second tread. It is open to both the center side main groove 36 (described later).
The first to fifth lug grooves and the first to eighth sipes may have their ends in the extending direction raised and shallower than the portion between both ends in the extending direction.

In the tire 10, the form of the region of the tread pattern on the other side in the tire width direction with respect to the tire center line CL is not particularly limited, and according to one embodiment, one side in the tire width direction described above. And line symmetry with respect to the tire center line CL, and according to another embodiment, with respect to the form on one side in the tire width direction and the point on the tire center line CL described above. It is point symmetric, and according to yet another embodiment, for example, it is the form on the other side (right side in FIG. 3) in the tire width direction with respect to the tire center line CL shown in FIG. Here, the form shown on the right side of FIG. 3 will be described.

When the shoulder side main groove is referred to as the first shoulder side main groove and the center side main groove is referred to as the first center side main groove described above, the tread pattern shown in FIG. 3 is on the other side with respect to the tire center line CL. In the area of, a second shoulder side main groove 38, a second center side main groove 36, a plurality of first shoulder sipes 51, a plurality of first shoulder lug grooves 53, and a plurality of first shoulder lug grooves 53. The middle lug groove 55, the plurality of first middle sipe 57, the plurality of second middle lug grooves 67, the plurality of second shoulder sipe 65, the plurality of second shoulder lug grooves 63, and the plurality of third It includes a shoulder sipe 71 and a plurality of third middle sipe 73.

The second shoulder-side main groove 38 and the second center-side main groove 36 are arranged on the other side (right side in FIG. 3) in the tire width direction with respect to the tire center line CL so as to be spaced apart from each other. It is a groove extending in the circumferential direction.

The first shoulder sipe 51 extends outward in the tire width direction from the closed end of the first shoulder lug groove 53 in the second shoulder land area 49, and is arranged at intervals in the tire circumferential direction.

The first shoulder lug groove 53 faces the second shoulder side main groove 38 from the outside in the tire width direction in the second shoulder land area 49 located outside the tire width direction of the second shoulder side main groove 38. It extends and is arranged at intervals in the tire circumferential direction.

The first middle lug groove 55 crosses the second shoulder side main groove 38 in the second middle land area 47 sandwiched between the second shoulder side main groove 38 and the second center side main groove 36. The first shoulder lug groove 53 extends from the side of the second shoulder side main groove 38 toward the second center side main groove 36 along the extending direction and is closed in the second middle land area 47. However, they are arranged at intervals in the tire circumferential direction. The direction in which the first shoulder lug groove 53 extends so as to cross the second shoulder-side main groove 38 is the extending direction of the end portion of the first shoulder lug groove 53 on the second shoulder-side main groove 38 side. Means.

The first middle sipe 57 extends from the closed end of the first middle lug groove 55 toward the second center side main groove 36 in the second middle land area 47, and is arranged at intervals in the tire circumferential direction. ing.

The second middle lug groove 67 extends the tire circumferential region between the first middle lug grooves 55 adjacent to each other in the tire circumferential direction from the side of the second center side main groove 36 in the second middle land region 47. It extends toward the second shoulder-side main groove 38 and is closed in the second middle land area 47, and is arranged at intervals in the tire circumferential direction.

The second shoulder sipe 65 crosses the shoulder side main groove 32 so as to extend the tire circumferential region between the first shoulder lug grooves 53 adjacent to each other in the tire circumferential direction in the second shoulder land region 49. The second sipe 64 extends from the side of the main groove 32 on the shoulder side to the outside in the tire width direction along the extending direction, and is alternately arranged with the first lug groove 52 at intervals in the tire circumferential direction.

The second shoulder lug groove 63 extends the tire circumferential region between the first shoulder lug grooves 53 adjacent to each other in the tire circumferential direction in the second shoulder land region 49, so that the second shoulder side main groove extends. From a position away from 38, the tread portion 10T extends to the outside in the tire width direction of the ground contact end 10b, and is arranged at intervals in the tire circumferential direction.

The third shoulder sipe 71 sets the tire circumferential region between the first shoulder lug groove 53 and the second shoulder lug groove 63 in the tire circumferential direction in the second shoulder land region 49. It extends outward in the tire width direction from the shoulder side main groove 38 side, and is arranged at intervals in the tire circumferential direction.

The third middle sipe 73 sets the tire circumferential region between the first middle lug groove 55 and the second middle lug groove 67 in the tire circumferential direction in the second middle land region 47 as the second shoulder side main. It extends from the groove 38 side to the side of the second center side main groove 36, and is arranged at intervals in the tire circumferential direction.

The form shown on the right side of FIG. 3 may include a shoulder groove 39. The shoulder narrow groove 39 is a groove that is arranged at a distance from the shoulder side main groove 38 in the shoulder land area 49, is narrower than the groove width of the shoulder side main groove 38, and extends in the tire circumferential direction.

(Comparative Examples, Examples)
In order to investigate the effect of the pneumatic tire of this embodiment, the tread pattern of the tire was variously changed, and the snow performance and noise performance were investigated. The prototype tire had a size of 225 / 65R17 and a cross-sectional shape shown in FIG. 2, and was based on the tread pattern shown in FIG. 3 except for the forms shown in Tables 1, 2 and the following.

Tables 1 and 2 show the morphology of each tire with respect to the tread pattern and the evaluation results thereof.
In Tables 1 and 2, regarding the column of "arrangement of the first to third lug grooves and the first sipe", the "extension line" is described above by the first to third lug grooves and the first sipe. It means that it extends to form the first extension line.
"Random 1" means that in the tread pattern shown in FIG. 3, the end of the first lug groove on the shoulder side main groove side and the end of the second lug groove on the shoulder side main groove side are farthest from each other. It means a form in which the shoulder land area is shifted in the tire circumferential direction with respect to the middle land area, and the form shown in Table 1 is adopted.
"Random 2" means that in the tread pattern shown in FIG. 3, the end of the first lug groove on the shoulder side main groove side and the end of the second lug groove on the shoulder side main groove side are farthest from each other. The middle land area is shifted in the tire circumferential direction with respect to the shoulder land area, in other words, the end of the fourth lug groove on the center side main groove side and the third lug groove on the center side main groove side. It means a form in which the middle land area is shifted in the tire circumferential direction with respect to the shoulder land area so that the ends are closest to each other, and the form shown in Table 1 is adopted.
"No first sipe" means a form in which the arrangement of the first to third lug grooves satisfies the above "extension line" except that the first sipe is not provided.
In Tables 1 and 2, regarding the column of "whether the fifth lug groove penetrates the main groove", "penetration" means that the fifth lug groove opens in the shoulder side main groove 32. To say.

The snow performance and noise performance of these test tires were evaluated by the following test methods, and the results are shown in Tables 1 and 2. Each evaluation was carried out under the condition that the test tire was assembled to a wheel having a rim size of 17 × 7J, mounted on a front-wheel drive vehicle having a displacement of 2400cc, and the air pressure after warming up was 230 kPa.

Snow performance Sensory evaluation of steerability, straightness, etc. when a test driver runs in the range of 0 to 80 km / hour on a test course on a snowy road surface where fresh snow road surface and compressed snow road surface are mixed after other vehicles have traveled. Was performed, and the index was shown with Comparative Example 1 as 100. The larger this index, the better the snow performance. Those with an index of 104 or more were evaluated as having excellent snow performance.

Noise Performance Each test tire was mounted on the same test vehicle used in the snow performance evaluation test, and the passing noise outside the vehicle was measured in accordance with the European Noise Regulation Conditions (ECE R117). The evaluation result is shown by an index with Comparative Example 1 as 100 using the reciprocal of the measured value. The larger this index is, the better the noise performance is. Those with an index of 100 or more were evaluated as being able to suppress the deterioration of noise performance.

Further, when the snow performance index is 104 or more and the noise performance index is 100 or more, the snow performance can be improved while suppressing the deterioration of the noise performance, that is, the snow performance and the noise. It was judged that both performance and performance could be achieved.

From the comparison between Examples 1 to 9 and Comparative Examples 1 to 4, the first lug groove, the second lug groove, the first sipe, and the third lug groove extend so as to form an extension line. Further, it can be seen that by providing the fourth lug groove, both snow performance and noise performance can be achieved at the same time.
From the comparison between Example 1 and Example 2, it can be seen that by providing the fourth lug groove, the noise outside the vehicle is reduced and the snow performance is further improved.
From the comparison between Example 2 and Example 3, it can be seen that by providing the second sipe, the noise outside the vehicle is reduced and the snow performance is further improved.
From the comparison between Example 3 and Example 4, it can be seen that by providing the third sipe, the noise outside the vehicle is reduced and the snow performance is further improved.
From these results, it can be seen that by providing the second to fourth sipes, the hitting sound on the road surface in the land area is reduced and the noise outside the vehicle is reduced.

From the comparison between Example 4 and Example 5, it can be seen that the noise outside the vehicle is reduced because the fifth lug groove is closed in the shoulder land area.
From the comparison between Example 5 and Example 6, it can be seen that the noise outside the vehicle is reduced because the outer end of the first lug groove in the tire width direction is located inside the ground contact end. Further, it can be seen that the same level of snow performance as when the outer end of the first lug groove in the tire width direction is located outside the ground contact end can be obtained.
From the comparison between Example 6 and Example 7, it can be seen that the snowiness is improved by overlapping the ranges in the tire width direction in which the second lug groove and the fourth lug groove extend.
From the comparison between Examples 8 and 7 and 9, the snow performance is improved when the inclination angles of the second lug groove, the third lug groove, and the fourth lug groove with respect to the tire circumferential direction are 50 ° or more. You can see that.

Although the pneumatic tire of the present invention has been described in detail above, the pneumatic tire of the present invention is not limited to the above-described embodiment or embodiment, and various improvements and changes have been made without departing from the gist of the present invention. Of course, it may be.

10 Tire 10T Tread 31 Shoulder narrow groove 32 Shoulder side main groove 34 Center side main groove 42 Shoulder land area 44 Middle land area 46 Center land area 50 Fifth sipe 52 First lug groove 54 Second lug Groove 56 1st sipe 58 3rd lug groove 60 5th lug groove 62 3rd sipe 64 2nd sipe 66 4th lug groove 68 6th sipe 72 8th sipe 74 4th sipe 76 7th sipe

Claims (12)

A pneumatic tire with a tread pattern on the tread.
The tread pattern is
On one side of the tire center line in the tire width direction, the shoulder side main groove and the center side main groove, which are arranged at intervals from each other and extend in the tire circumferential direction,
In the shoulder land region located outside the shoulder side main groove in the tire width direction, a plurality of first first portions extending from the outside in the tire width direction toward the shoulder side main groove and arranged at intervals in the tire circumferential direction. With a lug groove
In the middle land area sandwiched between the shoulder side main groove and the center side main groove, the side of the shoulder side main groove along the direction in which the first lug groove extends so as to cross the shoulder side main groove. A plurality of second lug grooves extending from the center side to the main groove, closing in the middle land area, and arranged at intervals in the tire circumferential direction.
In the middle land region, a plurality of first sipes extending from the closed end of the second lug groove toward the center side main groove and arranged at intervals in the tire circumferential direction,
The center side main groove is located inside the center side main groove in the tire width direction, and in the center land area passing through the tire center line, the center side main groove is extended along the direction in which the first sipe extends so as to cross the center side main groove. A plurality of third lug grooves extending from the groove side so as to move away from the center side main groove, closing in the center land area, and arranged at intervals in the tire circumferential direction are provided.
The first lug groove, the second lug groove, the first sipe, and the third lug groove extend so as to form a plurality of extension lines spaced apart from each other in the tire circumferential direction. death,
The tread pattern further extends the tire circumferential region between the adjacent extension lines from the center side main groove side toward the shoulder side main groove in the middle land portion region, and the middle land portion. A pneumatic tire comprising a plurality of fourth lug grooves that are closed within the region and are spaced apart in the tire circumferential direction. Further, in the middle land region, the tire circumferential region extends from the closed end of the fourth lug groove toward the shoulder side main groove so as to extend the tire circumferential region between adjacent extension lines, and is spaced in the tire circumferential direction. The pneumatic tire according to claim 1, further comprising a plurality of second sipes arranged apart from each other. Further, in the shoulder land region, the shoulder side main along the direction in which the second sipe extends so as to extend the tire circumferential region between the adjacent extension lines and across the shoulder side main groove. The pneumatic tire according to claim 2, further comprising a plurality of third sipes extending outward from the groove side in the tire width direction and alternately arranged with the first lug groove at intervals in the tire circumferential direction. Further, in the middle land region, the tire circumferential region between the second lug groove and the fourth lug groove in the tire circumferential direction is defined as the center side main groove from the shoulder side main groove side. The pneumatic tire according to any one of claims 1 to 3, further comprising a plurality of fourth sipes extending to the side and arranged at intervals in the tire circumferential direction. Further, in the shoulder land region, the tread portion extends from a position away from the shoulder side main groove to the outside in the tire width direction of the ground contact end of the tread portion so as to extend the tire circumferential region between adjacent extension lines. The pneumatic tire according to any one of claims 1 to 4, further comprising a plurality of fifth lug grooves arranged at intervals in the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 5, wherein the end portion of the first lug groove on the outer side in the tire width direction is closed on the inner side in the tire width direction of the ground contact end of the tread portion. Further, in the shoulder land region, a plurality of fifth sipes extending outward in the tire width direction along the extension line from the closed end of the first lug groove and arranged at intervals in the tire circumferential direction. The pneumatic tire according to claim 6. The range according to any one of claims 1 to 7, wherein the range in the tire width direction in which the second lug groove is located and the range in the tire width direction in which the fourth lug groove is located partially overlap. Pneumatic tires. The method according to any one of claims 1 to 8, wherein the inclination angles of the second lug groove, the third lug groove, and the fourth lug groove with respect to the tire circumferential direction are 50 ° to 90 °. Pneumatic tires. Further, in the center land region, a plurality of sixth sipes are arranged at intervals in the tire circumferential direction, extending along the direction in which the fourth lug groove extends so as to cross the center side main groove. The pneumatic tire according to any one of claims 1 to 9. Further, in the center land region, the tire circumferential region between the third lug groove and the sixth sipe is extended from the side of the center side main groove so as to be away from the center side main groove. The pneumatic tire according to claim 10, further comprising a plurality of seventh sipes arranged at intervals in the tire circumferential direction. Further, in the shoulder land region, the tread portion extends from a position away from the shoulder side main groove to the outside in the tire width direction of the ground contact end of the tread portion so as to extend the tire circumferential region between adjacent extension lines. A plurality of fifth lug grooves arranged at intervals in the tire circumferential direction,
In the shoulder land region, the tire circumferential region between the first lug groove and the fifth lug groove in the tire circumferential direction extends from the shoulder side main groove side to the outside in the tire width direction to extend the tire. The pneumatic tire according to any one of claims 1 to 11, further comprising an eighth sipe arranged at intervals in the circumferential direction.

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