JP2006143040A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire, improving traction performance on the snow and steering stability on a dry road surface while restraining the occurrence of uneven abrasion. <P>SOLUTION: In this pneumatic tire, a groove pattern of a tread inside area AIN located on the inner side of a vehicle when the tire is mounted on the vehicle, and a groove pattern of a tread outside area located on the outer side of the vehicle are disposed asymmetrically on both sides of a tire equator line E, a center block row 11 is disposed in a position across the tire equator line E of the tread T, a first rib 12 is disposed on the outer side of the vehicle of the center block row 11, outer block rows 14, 15 are disposed on the outer side of the vehicle of a second rib 13, inner block ribs 16, 17 are disposed on the inner side of the vehicle of the center block row 11, the pitch number on the periphery of the blocks included in the inner block rows 16, 17 is smaller than the pitch number on the periphery of the blocks included in the outer block rows 16, 17, and the proportion of the groove part to the tire outer peripheral length on the tire equator line E is set to 25 to 35%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire having an asymmetric tread pattern, and more particularly, a pneumatic tire capable of improving traction performance on snow and driving stability on a dry road surface while suppressing the occurrence of uneven wear. Regarding tires.

  In some pneumatic tires, the groove pattern in the inner region of the tread located on the inner side of the vehicle and the groove pattern in the outer region of the tread located on the outer side of the vehicle are asymmetrical on both sides of the tire equator line. 1-3).

  In a pneumatic tire having such an asymmetric tread pattern, it is possible to exhibit optimum driving performance according to vehicle characteristics by appropriately designing the groove pattern in the tread inner region and the groove pattern in the tread outer region. It is.

However, when the groove pattern in the tread inner region and the groove pattern in the tread outer region are different from each other, there is a drawback that uneven wear is likely to occur due to uneven rigidity balance. In addition, all-season tires are required to have both traction performance on snow and handling stability on dry roads. However, in the case of an asymmetric tread pattern, it is difficult to satisfy both performances at the same time. is there.
JP 7-257114 A JP-A-7-186622 JP 2003-170705 A

  An object of the present invention is a pneumatic tire having an asymmetric tread pattern, which is capable of improving traction performance on snow and driving stability on a dry road surface while suppressing occurrence of uneven wear. To provide tires.

  In order to achieve the above object, the pneumatic tire of the present invention is asymmetrical between the tire equatorial line on both sides of the tire equator line with the groove pattern in the inner region of the tread located inside the vehicle and the groove pattern in the outer region of the tread located outside the vehicle. In the pneumatic tire, the center block row is disposed at a position on the tire equator line of the tread, the first rib extending in the tire circumferential direction is disposed on the vehicle outer side of the center block row, and the first rib A second rib extending in the tire circumferential direction is disposed on the vehicle outer side, at least one outer block row is disposed on the vehicle outer side of the second rib, and at least one inner block is disposed on the vehicle inner side of the center block row. The number of pitches on the circumference of the blocks contained in the inner block row is less than the number of pitches on the circumference of the blocks contained in the outer block row. The ratio of groove to the tire circumferential length at the equator line is characterized in that the set 25 to 35%.

  In the present invention, the center block row is disposed at a position on the tire equator line of the tread, the first rib extending in the tire circumferential direction is disposed outside the vehicle in the center block row, and the first rib is disposed outside the vehicle. A second rib extending in the tire circumferential direction is arranged, at least one outer block row is arranged on the vehicle outer side of the second rib, and at least one inner block row is arranged on the vehicle inner side of the center block row. The rigidity balance between the tread inner area and the tread outer area is made uniform by making the number of pitches on the circumference of the blocks included in the inner block row smaller than the number of pitches on the circumference of the blocks included in the outer block row. And uneven wear resistance can be improved. Moreover, by mixing the land portion and the groove portion on the tire equator line of the tread and defining the ratio of the groove portion, it is possible to achieve both traction performance on snow and steering stability on a dry road surface.

  In the present invention, the first main groove adjacent to the vehicle outer side of the first rib is disposed at a position within 35% of the half width of the ground contact width from the tire equator line, and the second rib adjacent to the vehicle outer side of the second rib. The main groove is preferably arranged at a position within 60% of the half width of the ground contact width from the tire equator line. Thereby, the drainage performance in the tread central region where the contact pressure is highest can be improved.

  Moreover, it is preferable that the lug groove which divides the block of an outer side block row | line | column mutually is terminated between the 1st main groove and the 2nd main groove. Thereby, the wet performance and the hydroplaning performance can be improved without reducing the rigidity of the land portion arranged in the central region of the tread and without deteriorating the pattern noise caused thereby.

  Furthermore, it is preferable to provide a narrow vertical groove having a width of 2.0 mm or less extending in the tire circumferential direction at a position within 35% of the ground contact width from the ground contact end on the vehicle outer side toward the tire equator line. Thereby, the drainage performance at the time of cornering can be improved without impairing the responsiveness at the time of steering.

  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 according to an embodiment of the present invention. The tread pattern includes a groove pattern in the tread inner area A _IN located on the vehicle inner side (IN) and a groove pattern in the tread outer area A _OUT located on the vehicle outer side (OUT) on both sides of the tire equator line E. An asymmetric tread pattern made asymmetric.

As shown in FIG. 1, meandering grooves 1 extending in the tire circumferential direction while meandering in a wavy shape are formed in the vicinity of the tire equator line E of the tread T. The tread outer region A _OUT includes a main groove 2 (first main groove) extending straight in the tire circumferential direction from the tire equator line E side and a main groove 3 (straightly extending in the tire circumferential direction). The second main groove) and the narrow vertical groove 4 having a width of 2.0 mm or less, which extend in a straight shape in the tire circumferential direction, are sequentially formed. Further, a plurality of lug grooves 5 extending in the tire width direction while being curved in the same direction are formed in the tread outer area A _OUT at a predetermined interval in the tire circumferential direction. These lug grooves 5 extend from the design end of the tread T toward the tire equator line E side, and terminate between the main groove 2 and the main groove 3.

On the other hand, the tread inner area A _IN, from the tire equator line E side, the main groove 6 extending straight in the tire circumferential direction, likewise the main groove 7 extending straight in the tire circumferential direction are sequentially formed. Further, in the tread inside region A _IN, multiple lug grooves 8 that extend in the tire width direction while curving in the same direction are formed at predetermined intervals in the tire circumferential direction. These lug grooves 8 extend from the design end of the tread T toward the tire equator line E and communicate with the meandering grooves 1.

  As a result, a center block row 11 composed of a plurality of blocks 11a is defined at a position on the tire equator line E of the tread 1, and ribs 12 extending continuously in the tire circumferential direction on the vehicle outer side of the center block row 11. (First ribs) are defined, ribs 13 (second ribs) extending continuously in the tire circumferential direction are defined on the vehicle outer side of the ribs 12, and a plurality of blocks 14a are provided on the vehicle outer side of the ribs 13, respectively. , 15a, two outer block rows 14, 15 are partitioned, and inside the center block row 11, two inner block rows 16, 17 each consisting of a plurality of blocks 16a, 17a are partitioned. A sipe 9 is formed in each of the blocks 11a, 14a, 15a, 16a, and 17a.

In the pneumatic tire, the number of pitches on the circumference of the blocks 16a and 17a included in the inner block rows 16 and 17 is 5 or more less than the number of pitches on the circumference of the blocks included in the outer block rows 14 and 15. ing. Further, the ratio of the groove portion to the tire outer peripheral length on the tire equator line E is set to 25 to 35%. In other words, the tire circumferential length of the tire equator line E and L _1, the sum of the length of the portion where the tire equator line E crosses the groove when the L _2, of the L ₂ / L ₁ = 0.25~0.35 Satisfied relationship.

In the pneumatic tire having the above-described asymmetric tread pattern, the pitch number of the inner block rows 16 and 17 is smaller than the pitch number of the outer block rows 14 and 15, and therefore the tread inner region A _IN and the tread outer region A _OUT. And uniform wear resistance, and uneven wear resistance can be improved. In other words, the center block row 11 is disposed at a position on the tire equator line E of the tread T, and the rib 12 (first rib) extending in the tire circumferential direction is disposed on the vehicle outer side of the center block row 11. Ribs 13 (second ribs) extending in the tire circumferential direction are arranged on the vehicle outer side of the vehicle, two rows of outer block rows 14 and 15 are arranged on the vehicle outer side of the ribs 13, and the center block row 11 is arranged on the vehicle inner side. asymmetric tread pattern arranged inside block row 16, 17 of the two rows, there is a tendency that rigidity of the tread outer region a _OUT becomes relatively high due to the presence of the ribs 12 and 13, the tread inner area a _iN and the tread outer In order to keep the rigidity balance with the area A _OUT uniform, the number of pitches of the inner block rows 16 and 17 is relatively reduced.

  Moreover, since the land portion (block 11a) and the groove portion (meandering groove 1 or lug groove 8) are mixed on the tire equator line E of the tread T and the ratio of the groove portion is defined, the traction performance on the snow And handling stability on dry roads. Here, if the ratio of the groove portion to the tire outer peripheral length on the tire equator line E is less than 25%, the groove area at the portion where the contact pressure is highest is insufficient, so that the traction performance on the snow becomes insufficient. On the other hand, if it exceeds 35%, the rigidity at the portion where the ground pressure becomes the highest is insufficient, so that the steering stability on the dry road surface becomes insufficient.

  In the pneumatic tire, it is desired to appropriately set the groove position based on the contact width. However, the ground contact width is when the air pressure corresponding to the maximum load capacity is filled and the load of 80% of the maximum load capacity is applied in the air pressure-load capacity correspondence table specified in the JATMA Yearbook (2004 edition). Is the ground contact width.

  That is, the main groove 2 (first main groove) is disposed within 35% of the half width (TCW / 2) of the ground contact width TCW from the tire equator line E, and the main groove 3 (second main groove) is the tire. It is good to arrange at a position within 60% of the half width (TCW / 2) of the ground contact width TCW from the equator line E. By defining the positions of the main grooves 2 and 3 within the above range, it is possible to improve the drainage performance at the tread central portion where the contact pressure is highest.

  Further, the lug groove 5 that partitions the blocks 14a and 15a of the outer block rows 14 and 15 is terminated between the main groove 2 (first main groove) and the main groove 3 (second main groove). good. By defining the position of the end of the lug groove 5 in the above range, it becomes possible to improve the wet performance and the hydroplaning performance, but extremely reduce the rigidity of the land portion composed of the ribs 12 and 13. There is no worsening of pattern noise.

Further, the narrow vertical groove 4 may be disposed at a position within 35% of the half width (TDW / 2) of the ground contact width TDW from the ground contact end on the vehicle outer side toward the tire equator line E. By defining the position of the narrow vertical groove 4 within the above range, drainage performance during cornering can be improved without impairing responsiveness during steering. That is, even if the narrow vertical groove 4 is provided outside the grounded end of the tread outer region A _OUT , the hydroplaning performance during straight running is not improved. Even if the narrow vertical groove 4 is provided at a position more than 35% of the half width of the ground contact width TDW from the ground contact end on the outer side of the vehicle toward the tire equator line E, the drainage performance at the cornering is not improved. Due to the presence of the narrow vertical groove 4 in the region where the height becomes high, the response at the time of steering is lowered. The groove width of the narrow vertical groove 4 needs to be 2.0 mm or less, because when the groove width exceeds 2.0 mm, the block rigidity is lowered and the steering stability becomes insufficient.

  According to the pneumatic tire having the asymmetric tread pattern described above, it is possible to improve the traction performance on snow and the steering stability on the dry road surface while suppressing the occurrence of uneven wear. Therefore, it is suitable as an all-season tire required to adapt to various climates.

  In a pneumatic tire having a tire size of 205 / 65R15 and having an asymmetric tread pattern as shown in FIG. 1, the number of pitches on the circumference of the blocks included in the inner block row and the circumference of the blocks included in the outer block row The tires of Examples 1 to 3 and Comparative Examples 1 to 4 were manufactured in which the number of pitches and the ratio of the groove portion to the tire outer peripheral length on the tire equator line were varied as shown in Table 1. For comparison, a pneumatic tire (conventional example) having the same tire size and a symmetrical tread pattern mainly composed of blocks was prepared.

  These test tires were evaluated for snow traction performance, steering stability, and uneven wear resistance by the following test methods, and the results are also shown in Table 1.

Snow traction performance:
The test tire was mounted on a test vehicle under the condition of an air pressure of 200 kPa, and the feeling evaluation of the traction performance was performed by a test driver in a snowy test course. At that time, the air temperature was −10 ° C. and the road surface temperature was −4 ° C. The evaluation results are shown as an index with the conventional example being 100. A larger index value means better snow traction performance.

Steering stability:
The test tire was mounted on a test vehicle under the condition of an air pressure of 200 kPa, and a feeling of steering stability was evaluated by a test driver in a dry test course. The evaluation results are shown as an index with the conventional example being 100. A larger index value means better steering stability.

Uneven wear resistance:
After mounting the test tire on a test vehicle with a pressure of 200 kPa and running on a city for 40,000 km, the difference between the wear amount of the most worn portion and the wear amount of the least worn portion (uneven wear amount) Was measured. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. The larger the index value, the better the uneven wear resistance.

  As shown in Table 1, the tires of Examples 1 to 3 were able to improve on-snow traction performance and steering stability without reducing uneven wear resistance as compared with the conventional example. On the other hand, in the tires of Comparative Examples 1 to 4, the on-snow traction performance and the steering stability could not be improved at the same time without reducing the uneven wear resistance.

It is a top view which shows the tread pattern of the pneumatic tire which consists of embodiment of this invention.

Explanation of symbols

1 meandering groove 2, 3, 6, 7 main groove 4 narrow longitudinal groove 5, 8 lug groove 9 sipe 11, 14, 15, 16, 17 block row 12, 13 rib T tread E tire equator line A _IN tread inner area A _OUT tread outer area TCW Grounding width

Claims (4)

Position of the tread on the tire equator line in a pneumatic tire in which the groove pattern in the tread inner region located on the vehicle inner side and the groove pattern in the tread outer region located on the vehicle outer side are asymmetrical on both sides of the tire equator line when the vehicle is mounted The first block extending in the tire circumferential direction is arranged on the vehicle outer side of the center block row, and the second rib extending in the tire circumferential direction is arranged on the vehicle outer side of the first rib. And arranging at least one outer block row on the vehicle outer side of the second rib, arranging at least one inner block row on the vehicle inner side of the center block row, and on the circumference of the blocks included in the inner block row Is less than the number of pitches on the circumference of the blocks included in the outer block row, and the ratio of the groove portion to the tire outer circumference length on the tire equator line is 25. A pneumatic tire which is set to 35%. The first main groove adjacent to the vehicle outer side of the first rib is arranged at a position within 35% of the half width of the ground contact width from the tire equator line, and the second main groove adjacent to the vehicle outer side of the second rib is formed. The pneumatic tire according to claim 1, which is disposed at a position within 60% of a half width of a ground contact width from the tire equator line. The pneumatic tire according to claim 2, wherein lug grooves that divide the blocks of the outer block row from each other are terminated between the first main groove and the second main groove. 4. A narrow vertical groove having a width of 2.0 mm or less extending in the tire circumferential direction is provided at a position within 35% of the half width of the ground contact width from the ground contact end on the outer side of the vehicle toward the tire equator line. Pneumatic tires.

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