JP4899787B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire suitable as a studless tire, and more particularly to a pneumatic tire that improves running performance on snow and improves driving stability and wear resistance on a dry road surface.

  Generally, in a pneumatic tire, it is difficult to achieve both running performance on snow and running performance on a dry road surface. For example, in a pneumatic tire for icy and snowy roads, a tread portion is provided with a plurality of main grooves extending in the tire circumferential direction and a plurality of V-shaped lug grooves, and a large number of blocks are defined by the main grooves and the lug grooves. It has been proposed to improve the running performance and wear resistance on icy and snowy road surfaces by forming a directional tread pattern with a V-groove basic tone and appropriately arranging sipes on each block (for example, patents) Reference 1). However, in this case, since the lug groove opens in the main groove in the center of the tread, each block is small and the groove area is large, the running performance on the dry road surface becomes insufficient.

In the pneumatic tire for snowy and snowy roads, the tread portion is provided with a plurality of main grooves extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction, and a plurality of blocks are defined by the main grooves and the lug grooves. However, a plurality of sipes are provided in each block (see, for example, Patent Document 2). In such a pneumatic tire for icy and snowy roads, it is possible to demonstrate excellent running performance on snow by setting the groove area of the entire pattern large, but the block rigidity is insufficient by that much, especially heavy load In the heavy duty size, the steering stability and wear resistance on the dry road surface cannot be sufficiently exhibited.
Japanese Patent Laid-Open No. 5-301508 JP 2004-25954 A

  An object of the present invention is to provide a pneumatic tire capable of improving running performance on snow and improving driving stability and wear resistance on a dry road surface.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a first main groove extending in a tire circumferential direction at a tread portion and a first main groove in a pneumatic tire in which a tire front and back mounting direction with respect to a vehicle is specified. A second main groove extending in the tire circumferential direction in the shoulder region inside the vehicle, a third main groove extending in the tire circumferential direction in the shoulder region outside the vehicle from the first main groove, and the other shoulder from one shoulder side A plurality of lug grooves extending to the side, and the width of the first land portion defined between the first main groove and the second main groove is defined between the first main groove and the third main groove. The first land portion is provided with a plurality of inclined grooves communicating with the three lug grooves while being inclined with respect to the tire circumferential direction, and one end of the inclined groove is lug. While opening in the groove, the other end is terminated in the block, and the first The lug groove located at both ends of the three lug grooves in the part is communicated with the first main groove, while the lug groove located in the middle is not communicated with the first main groove, Three types of blocks divided by the three lug grooves and the inclined grooves are arranged as a repeating unit in one land part, and the first block is compared with the blocks A and B located on the vehicle inner side of the first land part. The block G located outside the vehicle in one land portion is relatively large.

  In the present invention, the tread portion is divided into a plurality of rows of land portions by the first main groove, the second main groove, and the third main groove, and the width of the first land portion inside the vehicle is set to the width of the second land portion outside the vehicle. The long slope groove is arranged in the 1st land part. With the above configuration, the block rigidity can be optimized, steering stability and abrasion resistance on the dry road surface can be sufficiently ensured, and steering stability on snow based on the inclined grooves arranged in the first land portion And traveling performance such as turning performance can be improved. In particular, three types of blocks partitioned by three lug grooves and inclined grooves are arranged as repeating units in the first land portion, and the first block is compared to the blocks A and B located inside the vehicle in the first land portion. Since the block G located outside the vehicle in the land portion is relatively large, it is possible to improve steering stability on a dry road surface and to sufficiently exhibit turning performance on snow.

In the present invention, in order to achieve both running performance on snow and steering stability and wear resistance on a dry road surface, the groove width x1 at the vehicle inner side in the first land portion of the lug groove, The groove width x2 between the inclined grooves and the groove width x3 at the vehicle outer side in the first land portion may be set as follows.
x2 = x1 × 101% to 180%
x3 = x1 × 60% to 99%

  Furthermore, the inclination angle of the portion adjacent to the block G of the lug groove with respect to the tire circumferential direction is set to 60 ° to 90 °, and the width of the first land portion is set to 50% to 70% of the ground half width, while the second land portion The width is set to 15% to 35% of the ground contact half width, and the groove width y1 in the vehicle outer portion in the second land portion of the lug groove is set to 40% to 50% of the groove width y2 in the vehicle inner portion in the second land portion. The inclination angle of the inclined groove with respect to the tire circumferential direction is 10 ° to 30 °, and the total groove width of the first main groove, the second main groove, and the third main groove is 15 of the tread ground contact width. % To 35% is also effective in achieving both running performance on snow, steering stability on a dry road surface, and wear resistance.

  In the present invention, when a pneumatic tire for an icy and snowy road represented by a studless tire is configured, it is preferable to provide a plurality of sipes extending in the tire width direction in each land portion including the first land portion and the second land portion. . The present invention provides a remarkable effect when applied to a pneumatic tire for icy and snowy roads, but can also be applied to a pneumatic tire for all seasons.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a tread pattern of a pneumatic tire for icy and snowy roads according to an embodiment of the present invention. In the pneumatic tire of this embodiment, the mounting direction of the tire front and back with respect to the vehicle is specified. In FIG. 1, IN is the vehicle inner side, and OUT is the vehicle outer side.

  As shown in FIG. 1, the tread portion 1 includes a main groove 11 (first main groove) extending in the tire circumferential direction in the tread central region, and a main groove extending in the tire circumferential direction in a shoulder region inside the vehicle from the main groove 11. A groove 12 (second main groove), a main groove 13 (third main groove) extending in the tire circumferential direction in a shoulder region outside the vehicle from the main groove 11, and a plurality of grooves extending from one shoulder side to the other shoulder side Lug grooves 14 are formed. Thereby, a land portion 21 (first land portion) is defined between the main groove 11 and the main groove 12, and a land portion 22 (second land portion) is defined between the main groove 11 and the main groove 13. Further, a land portion 23 (third land portion) is defined outside the main groove 12 in the tire width direction, and a land portion 24 (fourth land portion) is defined outside the main groove 13 in the tire width direction. ing. And the width of the land portion 21 is larger than the width of the land portion 22.

  A plurality of inclined grooves 15 that communicate with the three lug grooves 14 while being inclined with respect to the tire circumferential direction are formed in the land portion 21. The inclined groove 15 is arranged so that the other end 15b terminating in the block faces the vehicle inside. One end 15a of the inclined groove 15 opens into the lug groove 14, and the other end 15b terminates in the block. In the land portion 21, the lug grooves 14 a located at both ends of the three lug grooves 14 that communicate with the inclined groove 15 communicate with the main groove 11, but the lug groove 14 b located in the middle is the main groove 11. Is out of communication. More specifically, the lug groove 14 a crosses the land portion 21 while being bent in a V shape, and the lug groove 14 b communicates with the main groove 12, but does not communicate with the main groove 11. . These lug grooves 14 a and 14 b are alternately arranged in the tire circumferential direction in the land portion 21. Thereby, three types of blocks having different shapes defined by the three lug grooves 14a, 14b and the inclined grooves 15 are arranged in the land portion 21 as repeating units. Then, compared to the block A located on the other end side of the inclined groove 15 on the vehicle inner side of the land portion 21 and the block B located on the one end side of the inclined groove 15 on the vehicle inner side of the land portion 21, The located block G is relatively large. The circumferential length of the block G is substantially equal to the circumferential length of the aggregate of the blocks A and B. On the other hand, a plurality of blocks partitioned by the lug grooves 14 are formed in the land portions 22 to 24, respectively.

  Each block included in the land portions 21 to 24 is formed with a plurality of sipes 16 extending in the tire width direction. The shapes of these sipes 16 are not particularly limited, and those having a zigzag shape or a linear shape in a plan view, or those having a three-dimensional shape can be employed.

  In the pneumatic tire, the tread portion 1 is divided into four rows of land portions by the three main grooves 11 to 13, and the width of the land portion 21 on the vehicle inner side is made larger than the width of the land portion 22 on the vehicle outer side, By providing the long inclined groove 15 with respect to the wide land portion 21, the block rigidity is optimized, so that the steering stability and the wear resistance on the dry road surface can be sufficiently ensured. Moreover, traveling performance such as steering stability and turning performance on snow can be improved based on the inclined groove 15 of the land portion 21.

  In addition, the block A located on the inner side of the land portion 21 is arranged in the land portion 21 by repeating three types of blocks A, B, and G divided by the three lug grooves 14a and 14b and the inclined groove 15 as a repeating unit. Compared to B, the block G located outside the land portion 21 is relatively large, so that the driving stability on the dry road surface can be improved and the turning performance on snow can be fully demonstrated. can do.

  The width W1 of the land portion 21 is set to 50% to 70% of the ground half width, and the width W2 of the land portion 22 is set to 15% to 35% of the ground half width. By setting the width of the land portions 21 and 22 within the above range, it is possible to improve the running performance on the dry road surface and the running performance on the snow in a well-balanced manner. When the width W1 of the land portion 21 is less than the above range, the inclination of the inclined groove 15 becomes insufficient and the steering stability on the snow is lowered. Stability and turning performance are reduced. The contact half width is the air pressure-load capacity correspondence table specified in the JATMA Yearbook (2006 edition). The tire is filled with air pressure corresponding to the maximum load capacity and multiplied by 80% of the load capacity. Is a half of the tread contact width TCW measured in the tire axial direction.

The groove width of the lug groove 14 is optimized according to the position in the tire width direction. That is, as shown in FIG. 2, the groove width x1 of the lug groove 14 in the vehicle inner portion in the land portion 21, the groove width x2 between the inclined grooves 15 and 15 in the land portion 21, and the vehicle in the land portion 21. The groove width x3 at the outer portion is set to the following relationship. However, when the lug groove 14 is locally expanded by chamfering the block at the communication portion with the main groove, the groove widths x1 and x3 are the groove widths of the portion excluding the enlarged portion.
x2 = x1 × 101% to 180%
x3 = x1 × 60% to 99%

  By reducing the groove width x3 in this manner, the groove area in the tread central region can be reduced, and the running performance on dry road surface and ice can be improved, and the groove width x2 between the inclined grooves 15 and 15 is increased. By doing so, it is possible to improve steering stability and turning performance on snow.

  In FIG. 2, the inclination angle α of the portion adjacent to the block G of the lug groove 14a with respect to the tire circumferential direction is set to 60 ° to 90 °. Thereby, the edge component of the tire width direction in a center area | region can be ensured, and the traction performance on snow can fully be ensured. When the inclination angle α is less than 60 °, the traction performance on snow is lowered. In addition, the part adjacent to the block G of the lug groove 14a may incline in any direction with respect to the tire circumferential direction.

  As shown in FIG. 3, the groove width y <b> 1 at the vehicle outer side portion in the land portion 22 of the lug groove 14 is set to 40% to 50% of the groove width y <b> 2 at the vehicle inner portion in the land portion 22. However, when the lug groove 14 is locally expanded by chamfering the block at the communication portion with the main groove, the groove widths y1 and y2 are the groove widths of the portion excluding the enlarged portion. By making the groove width y1 narrower than the groove width y2, the running performance on the dry road surface and the running performance on snow can be improved in a balanced manner. When the groove width y1 exceeds the above range, the turning performance on the dry road surface decreases, and conversely, when the groove width y1 falls below the above range, the traction performance on snow decreases. In addition, when placing importance on dry performance, the lug groove 14 may be closed in the middle of the land portion 22 (see FIG. 4).

  The inclination angle θ of the inclined groove 15 with respect to the tire circumferential direction is set to 10 ° to 30 °. When the inclination angle θ of the inclined groove 15 is larger than the above range, the dimensional difference between the blocks in the land portion 21 becomes large and the block rigidity becomes non-uniform so that the uneven wear resistance is reduced. When turning, the effect of the inclined groove 15 cannot be sufficiently exhibited, and the steering stability on snow is lowered.

  The total groove width of the main grooves 11 to 13 is set to 15% to 35% of the tread ground contact width TCW. When the sum of the groove widths of the main grooves 11 to 13 is less than 15% of the tread ground contact width TCW, the wet performance is lowered, and conversely, when it exceeds 35%, the steering stability on the dry road surface is lowered.

  In the pneumatic tire for snowy and snowy roads having a tire size of 205 / 55R16, tires of a conventional example and Examples 1 and 2 in which only the tread pattern was varied were manufactured.

  In the conventional example, five main grooves extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction are provided in the tread portion, and a number of rectangular blocks are partitioned by these main grooves and lug grooves. is there. On the other hand, Example 1 has a tread pattern shown in FIG. 1, and Example 2 has a tread pattern shown in FIG. In Examples 1 and 2, the width of the first land portion is 56% of the tread ground half width, the width of the second land portion is 27% of the tread ground half width, and the inclination angle of the inclined groove with respect to the tire circumferential direction is 15 °. The sum of the groove widths of the first main groove, the second main groove, and the third main groove was 21.4% of the tread ground contact width.

  These test tires were evaluated for steering stability on a dry road surface, steering stability on snow, turning performance on snow, and wear resistance by the following test methods, and the results are shown in Table 1.

Steering stability on dry roads:
The test tire was mounted on a wheel having a rim size of 16 × 6.5 J, mounted on a rear-wheel drive vehicle with a displacement of 2000 cc with an air pressure of 200 kPa, and sensory evaluation was performed by a test driver on a dry road test course. The evaluation results are shown as an index with the conventional example being 100. The larger the index value, the better the steering stability on the dry road surface.

Steering stability on snow:
The test tire was mounted on a wheel having a rim size of 16 × 6.5 J, mounted on a rear-wheel drive vehicle having a displacement of 2000 cc with an air pressure of 200 kPa, and sensory evaluation was performed by a test driver on a test course on snow. The evaluation results are shown as an index with the conventional example being 100. The larger the index value, the better the handling stability on snow.

Swirl on snow:
The test tire was mounted on a wheel having a rim size of 16 × 6.5 J, mounted on a rear-wheel drive vehicle having a displacement of 2000 cc with an air pressure of 200 kPa, and sensory evaluation was performed by a test driver on a test course on snow. The evaluation results are shown as an index with the conventional example being 100. The larger the index value, the better the turning performance on snow.

Abrasion resistance:
The test tire is mounted on a wheel with a rim size of 16x6.5J, mounted on a rear-wheel drive vehicle with a displacement of 2000cc with an air pressure of 200kPa, and after running about 10,000km on a dry road, the amount of wear at the tread center position is measured. did. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. A larger index value means better wear resistance.

  As can be seen from Table 1, the tires of Examples 1 and 2 have excellent driving stability on a dry road surface, driving stability on snow, turning on snow, and wear resistance in comparison with the conventional example. It was.

It is an expanded view which shows the tread pattern of the pneumatic tire for snowy and icy roads which consists of embodiment of this invention. It is a top view which expands and shows the 1st land part in FIG. It is a top view which expands and shows the 2nd land part in FIG. It is an expanded view which shows the modification of the tread pattern of FIG.

Explanation of symbols

1 tread 11 main groove (first main groove)
12 Main groove (second main groove)
13 Main groove (3rd main groove)
14, 14a-14e lug groove 15 inclined groove 15a one end of inclined groove 15b other end of inclined groove 16 sipe 21 land part (first land part)
22 Land (second land)
23 Land (Third Land)
24 Land (4th Land)
A, B, G block

Claims (8)

  In a pneumatic tire in which a tire front and back mounting direction with respect to a vehicle is specified, a tread portion includes a first main groove extending in the tire circumferential direction, and a second extending in the tire circumferential direction in a shoulder region on the vehicle inner side than the first main groove. A main groove, a third main groove extending in the tire circumferential direction in a shoulder region outside the vehicle from the first main groove, and a plurality of lug grooves extending from one shoulder side to the other shoulder side; The width of the first land portion partitioned between the groove and the second main groove is made larger than the width of the second land portion partitioned between the first main groove and the third main groove, The land portion is provided with a plurality of inclined grooves communicating with the three lug grooves while being inclined with respect to the tire circumferential direction, and one end of the inclined groove is opened in the lug groove while the other end is terminated in the block. , Lug grooves located at both ends of the three lug grooves in the first land portion The lug groove positioned in the middle while communicating with the first main groove is not communicated with the first main groove, and is partitioned by the three lug grooves and the inclined groove in the first land portion. The three types of blocks are arranged as repeating units, and the block G located outside the first land portion of the vehicle is relatively larger than the blocks A and B located inside the vehicle of the first land portion. A pneumatic tire characterized by that. A groove width x1 at the vehicle inner side portion in the first land portion of the lug groove, a groove width x2 between the pair of inclined grooves in the first land portion, and a groove width x3 at the vehicle outer portion in the first land portion,
x2 = x1 × 101% to 180%
x3 = x1 × 60% to 99%
The pneumatic tire according to claim 1, wherein the relationship is   The pneumatic tire according to claim 1 or 2, wherein an inclination angle of a portion of the lug groove adjacent to the block G with respect to a tire circumferential direction is 60 ° to 90 °.   The pneumatic tire according to any one of claims 1 to 3, wherein the width of the first land portion is 50% to 70% of the ground contact half width, and the width of the second land portion is 15% to 35% of the ground contact half width. .   The groove width y1 in the vehicle outer side part in the 2nd land part of the said lug groove is 40%-50% of the groove width y2 in the vehicle inner side part in the 2nd land part. Pneumatic tire.   The pneumatic tire according to any one of claims 1 to 5, wherein an inclination angle of the inclined groove with respect to a tire circumferential direction is 10 ° to 30 °.   The pneumatic tire according to any one of claims 1 to 6, wherein a total sum of groove widths of the first main groove, the second main groove, and the third main groove is 15% to 35% of a tread ground contact width.   The pneumatic tire according to any one of claims 1 to 7, wherein a plurality of sipes extending in a tire width direction are provided in each land portion including the first land portion and the second land portion.

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