JPH115415A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously enhance tire front and rear performance, namely, braking performance, accelerating performance, and turning performance on an ice road. SOLUTION: A pneumatic tire has blocks 2 having a plurality of sipings 3, respectively in the tire width direction on a tire tread part 1. Where, adjoining primary siping 3a and adjoining secondary sipings 3b extended in the tire width direction are formed while spacing apart in the tire peripheral direction at different angles in the same block on the blocks 2b of block rows 2B at an intermediate region and on the blocks 2c of block rows 2C at a shoulder region. Each primary siping 3a is a parallel siping extended in parallel with the tire width direction. Each secondary siping 3b is a inclined siping extended with an angle in the tire width direction. The primary siping 3a and the secondary siping 3b are alternately formed by adjoining to one another.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire, and more particularly to a pneumatic radial tire having improved turning performance while maintaining braking performance and acceleration performance on icy and snowy road surfaces.

[0002]

2. Description of the Related Art In conventional studless tires, a number of sipes have been arranged in blocks on the tire tread as a means for improving the performance on ice and snowy roads. The conventional arrangement direction of the sipe is arranged at 90 ° with respect to the circumferential direction of the tire. In addition, 0 to 5 with respect to the circumferential direction of the tire.
The blocks were arranged at an angle of 0 ° and the sipes were arranged parallel to this block angle, or the sipes were arranged parallel to each other regardless of the block angle. Studless tires in which sipes are not parallel to each other on the block surface but are arranged at irregular angles without regularity have also been proposed.

[0003]

However, when a large number of sipes are arranged in blocks at 90 ° to the circumferential direction of the tire, the edge effect of the sipes tends to be effective in the traveling direction. Although the front-rear performance of the tire, that is, the braking performance and the acceleration performance, are high, the turning performance is often low.

On the other hand, 0 to 50 with respect to the circumferential direction of the tire.
The blocks are placed at an angle of °, and the sipe is placed parallel to this block angle, or in the case of a tire placed with the sipes parallel to each other regardless of the block angle, the sipe is placed in the direction of travel of the tire. Due to the angle, the turning effect on ice and snow road surface is high because the edge effect is easily exerted during turning, but the front-rear performance, that is, the braking performance and the acceleration performance are low.

[0005] Further, in the case of a tire in which sipes are not parallel to each other on the block surface but are arranged at irregular angles without regularity, the front-rear performance and the turning performance of the tire on an icy and snowy road surface are deteriorated as compared with the above-described tire. It does not improve the front-rear performance and turning performance of the tire at the same time.

An object of the present invention is to provide a pneumatic radial tire capable of simultaneously improving the front-rear performance, ie, braking performance and acceleration performance, and turning performance on an icy and snowy road surface.

[0007]

As a result of intensive studies to solve the above problems, the present invention relates to a pneumatic radial tire having a block having a plurality of sipes extending in a tire width direction on a tire tread portion. A pneumatic radial tire in which the primary sipe and the secondary sipe that extend in the tire width direction while being spaced apart in the tire circumferential direction at different angles in the same block and are regularly formed in whole or in part is adopted. .

[0008] According to this configuration, a minimum separation area and a maximum separation area appear on the block surface between the adjacent primary sipe and secondary sipe, and the minimum separation area is smaller than that of the conventional tire. As a result, the sipe end edge effect is improved. Also,
According to such a configuration, a parallel sipe extending parallel to the tire width direction in the same block is defined as a primary sipe, and an inclined sipe extending at an angle to the tire width direction is defined as 2 primary sipe.
The primary sipe and the secondary sipe can be formed alternately and regularly alternately adjacent to each other while being separated from each other. Therefore, the secondary sipe extending at an angle to the tire width direction increases the edge effect in the lateral direction of the vehicle, that is, in the tire width direction, so that the turning performance on the icy and snowy road surface is greatly improved. Moreover, the primary sipe extending parallel to the tire width direction enhances the edge effect in the front-rear direction of the vehicle, that is, in the tire circumferential direction, so that the braking performance and the acceleration performance, which are the front-rear performance on an icy and snowy road surface, can be maintained.

[0009]

FIG. 1 is a front view of an entire tire showing an embodiment of a pneumatic radial tire according to the present invention. FIG. 2 is a partially enlarged view of the tread pattern in a region between AA 'and BB' in FIG. FIG.
FIG. 3 is a partially enlarged view further enlarging a region C in FIG. 2.

In the drawing, reference numeral 1 denotes a tire tread portion, and reference numeral 2 denotes a block provided with a plurality of sipes 3 extending in the tire width direction on the tire tread portion 1. 4 is a circumferential groove. The block 2 of the present embodiment includes a center region block rows 2A, 2A arranged in the tire circumferential direction on both sides of the central circumferential groove 4a in the center region of the tire tread portion, and further in the tire width direction. Block rows 2B, 2B in the intermediate area located on both sides
And block rows 2C, 2C of shoulder regions located on both sides in the tire width direction.

That is, as shown in FIG. 2, the blocks 2a, 2a of the block rows 2A, 2A in the central area are formed in a central circumferential groove 4 running in the central area in the central area of the tire tread portion 1.
a and zigzag circumferential grooves 4b, 4b extending in a zigzag manner on both sides thereof, and the zigzag circumferential grooves 4b, 4b.
b and the central circumferential groove 4a are partitioned and arranged by an inclined groove 5 that connects diagonally in the tire width direction.
Further, the blocks 2b, 2b of the block rows 2B, 2B in the intermediate region located on both sides in the tire width direction include the zigzag circumferential grooves 4b, 4b and the zigzag circumferential grooves 4b.
b, straight circumferential grooves 4c located on both sides of 4b,
4c are connected to each other by a lateral groove 6 extending parallel to the tire width direction. Furthermore, the blocks 2c and 2c of the block rows 2C and 2C in the shoulder area
Are defined by connecting the straight circumferential grooves 4c, 4c and the shoulder end 7 with a lateral groove 8 extending parallel to the tire width direction.

In this embodiment, as shown in FIG. 2, the blocks 2a, 2a of the block rows 2A, 2A in the central area include:
A plurality of parallel sipes 3d extending parallel to the tire width direction are formed. Block row 2B, 2B in the middle area
Blocks 2b, 2b and the blocks 2c, 2c of the shoulder area block rows 2C, 2C are adjacent to each other in the same block at different angles in the tire circumferential direction while being separated from each other in the tire circumferential direction. And 2
The next sipes 3b are formed by repeating regularly.
As shown, the primary sipe 3a is a parallel sipe extending parallel to the tire width direction, and the secondary sipe 3b is an inclined sipe extending at an angle to the tire width direction.

Therefore, as shown in FIG. 3, the tire according to this embodiment has a minimum separation area 9 between the adjacent primary sipe 3a and secondary sipe 3b on the surfaces of the blocks 2b and 2c.
And the maximum separation area 10 appears. FIG. 4 shows five parallel sipes 1 formed on a block 11 of a conventional tire.
FIG. 2 is an enlarged schematic plan view of a main part showing No. 2; Block 1 in FIG.
1 has a slightly different shape from the block 2 of the above-described embodiment, but suppose that the size of the block is the same, the number and density of the sipes are the same, and When the separation region 13 is compared with the minimum separation region 9 of the embodiment of the main body, the ground pressure becomes higher in the minimum separation region 9 and the sipe end edge effect is improved.
The effect of the present embodiment is that the sipe end edge effect is ensured by causing the minimum separation region 9 to appear regularly despite the presence of the maximum separation region 10 in the same block.

In this embodiment, the primary sipe 3a is larger than the secondary sipe 3b especially in the blocks 2b and 2b of the block rows 2B and 2B in the intermediate area, and the blocks 2c and 2c of the block rows 2C and 2C in the shoulder area are provided. In 2c, the secondary sipe 3b is arranged more than the primary sipe 3a. Thus, the block 2 of the block row 2B, 2B in the intermediate area
By increasing the number of primary sipes 3a which are parallel sipes to b and 2b, the braking performance and the front-back performance on the icy and snowy road surface can be effectively exhibited, and the blocks 2c and 2c of the block rows 2C and 2C in the shoulder region are provided. By arranging a large number of secondary sipes 2b, which are inclined sipes, braking performance on ice and snow road surfaces can be effectively exhibited.

The primary sipe 3a and the secondary sipe 3b arranged in the block row 2B in the intermediate area are open sipes on both sides which open in the zigzag circumferential groove 4b and the straight circumferential groove 4c, respectively. Like the block row 2C of the area, the primary sipe 3a may be an open sipe on both sides, and the secondary sipe 3b may be an open sipe on one side opened in the straight circumferential groove 4c. Further, both ends may be closed sipes. In short, if the minimum spacing area appears regularly and repeatedly between the adjacent primary sipe and secondary sipe, the minimum spacing area is cumulatively secured because of the regularity,
This increases the ground pressure and produces a sipe end edge effect.

As shown in FIG. 5, of the minimum separation area 9 and the maximum separation area 10 between the primary sipe 3a and the secondary sipe 3b, the tertiary sipe 3c is further provided in the maximum separation area 10.
Is preferably formed. By forming such a tertiary sipe 3c, the maximum separation area 10 between the primary sipe 3a and the secondary sipe 3b is cut by the tertiary sipe 3c to secure a high ground pressure area in the maximum separation area 10 as well. can do. Therefore, this third sipe 3c
Is a one-sided open sipe, one end of which is closed and one side of which is open to the tire circumferential groove 4, and as shown in FIG. 5, a maximum separation area 10 between the primary sipe 3a and the secondary sipe 3b.
It is desirable to form within the range. This third sipe 3
c may be formed so as to extend beyond the maximum separation region 10 between the primary sipe 3a and the secondary sipe 3b to an intermediate region 14 between the maximum separation region 10 and the minimum separation region 9. In such a case, the wear resistance deteriorates, which is not preferable. The tertiary sipe 3c is preferably formed in parallel with the secondary sipe 3b as shown in the present embodiment, but may be formed in parallel with the primary sipe 3a.

As shown in FIG. 3, the minimum separation distance A specifying the minimum separation region 9 between the primary sipe 3a and the secondary sipe 3b is the primary sipe 3a adjacent to the secondary sipe 3b. , Where X is the separation distance between 3a, A = 0.2
X to 0.4X is preferable. If the minimum separation distance A is out of the range of 0.2X to 0.4X, in any case, the sipe interval between the primary sipe 3a and the secondary sipe 3b becomes narrow, resulting in deterioration of wear resistance.

As described above, when the tertiary sipe 3c is further formed in the maximum separation region 10 between the primary sipe 3a and the secondary sipe 3b, as shown in FIG.
The maximum separation distance B from the next sipe 3c is
a = 0.3X-0.
It is preferably 45X. If the maximum separation distance B between the primary sipe 3a and the tertiary sipe 3c is out of the above range, the sipe interval becomes narrower in any case, resulting in deterioration of wear resistance.

The sipe density per unit block of the primary sipe 3a and the secondary sipe 3b is 0.1 to 0.2 mm / mm ^2.
It is desirable that The sipe density per unit block of the primary sipe 3a and the secondary sipe 3b is 0.1 mm / mm ²
If it is less than 10, the sipe density becomes too low, and the effect of maintaining the braking performance and acceleration performance on ice and snow road surfaces and improving the turning performance is poor. On the other hand, the sipe density per unit block of the primary sipe 3a and the secondary sipe 3b is 0.2 mm / m
If more than m ^2, the wear resistance is deteriorated sipe interval is too narrow.

The above-mentioned primary sipe 3a and secondary sipe 3b
Can be formed on the entire block, but can also be formed on a part of the block. When it is formed in a part of a block, as in the above-described embodiment, it is formed in the entire block of a specific block row, or the primary sipe 3a and the secondary sipe 3b are combined with other sipes in one block. You can also. Further, the primary sipe 3a and the secondary sipe 3b can be all straight sipe, but as in the present embodiment, both ends can be straight sipe and the middle part can be zigzag sipe.

In this embodiment, the primary sipe and the secondary sipe
The next sipes extend in the tire width direction while being spaced apart in the tire circumferential direction and are formed adjacently and alternately,
They do not necessarily have to be formed alternately. For example, a regular pattern in which a secondary sipe is formed after a primary sipe, and a primary sipe is formed after a secondary sipe is formed may be used. Further, in the present embodiment, the inclination directions of the secondary sipes are all in the same direction with respect to the tire width direction, but the secondary sipes in different directions can be formed regularly. For example, after the primary sipe, a secondary sipe having a certain inclination direction is formed, and then the primary sipe is formed again. A secondary sipe is formed in the next secondary sipe, which is inclined in a direction opposite to the inclination direction. Then, it is a pattern for forming a primary sipe.

[0022]

EXAMPLE A radial tire having a tire size of 185 / 70R14 and having the configuration shown in FIG. 1 according to Example 1 was trial-produced, mounted on a front-wheel-drive ordinary passenger car with a displacement of 1800 cc, and snow-dried in actual vehicle running. The braking performance, acceleration performance and turning performance on the road surface were evaluated respectively. Also, for comparison, the braking performance on an icy and snowy road surface was the same as that of the comparative example tire except that the sipes on the block surface were all parallel sipes extending parallel to the tire width direction.
The acceleration performance and turning performance were evaluated. In addition, a tire having the same configuration as that shown in FIG. 1 except that the tertiary sipe as shown in FIG. 5 was formed in the maximum separation region of the blocks in the intermediate region and the shoulder region was also prototyped, and the braking performance and the acceleration on the icy and snowy road surface were obtained. The performance and turning performance were evaluated. Referring to FIG. 5, the tertiary sipe was formed with a dimension H1 of 3 mm, which is about 1 / 6H of the maximum dimension H in the block width direction.

Table 1 shows the test results of the braking performance, the acceleration performance and the turning performance on the icy and snowy road surface for each tire of Example 1, Example 2 and Comparative Example.

The braking performance on an icy and snowy road surface is a speed of 40 km.
The reciprocal of the braking distance when full lock is applied from / h is indicated as an index as the comparative tire 100. The larger the value, the better the braking performance.

The acceleration performance on ice and snow road surface is 3
The reciprocal of the running time up to 0 m is indicated as an index as the comparative tire 100. The higher the value, the better the acceleration performance.

The turning performance on an iced and snowy road surface is indicated by the index of the reciprocal of the lap time in a circuit having a lemniscate curve (figure 8) as a comparative tire 100. The larger the value, the better the turning performance. Further, the wear resistance performance is indicated as an index with the reciprocal of the step difference (mm) between sipes after traveling 8000 km as Comparative Example 100. The larger the value, the better the wear resistance.

[0027]

[Table 1]

From Table 1, it can be seen that the tires of the example have significantly improved turning performance while maintaining braking performance and acceleration performance on icy and snowy road surfaces as compared with the comparative example tires. However, the minimum separation distance A between the primary sipe and the secondary sipe is from the range of A = 0.2X to 0.4X, where X is the separation distance between the primary sipe adjacent to the secondary sipe. When it deviated, in any case, the sipe interval between the primary sipe and the secondary sipe became narrow, and as a result, the wear resistance deteriorated. Accordingly, the minimum separation distance A between the primary sipe and the secondary sipe is preferably set in the range of A = 0.2X to 0.4X since a tire can maintain wear resistance.

Further, in the case of the tires of Examples 5 to 8 in which a tertiary sipe is further formed in the maximum separation area between the primary sipe and the secondary sipe, the maximum value between the primary sipe and the tertiary sipe is set. The separation distance B is represented by B to the separation distance X between the primary sipe.
= 0.3X to 0.45X, the sipe interval became narrower in any case, resulting in poor wear resistance. Accordingly, the tire having the maximum separation distance B between the primary sipe and the tertiary sipe in the range of 0.3X to 0.45X is optimal in that the wear resistance can be maintained.

[0030]

As described above, according to the present invention, the primary sipe and the secondary sipe extending substantially in the tire width direction while being separated in the tire circumferential direction at different angles in the same block are regularly arranged. Formed between the primary sipe and the secondary sipe adjacent to each other, a minimum separation region where the ground pressure is high on the block surface is exerted. Acceleration performance and turning performance were improved.

In particular, a parallel sipe extending parallel to the tire width direction in the same block is constituted as a primary sipe, and an inclined sipe extending at an angle to the tire width direction is constituted as a secondary sipe. In the case of a tire in which a primary sipe and a secondary sipe are formed alternately and regularly alternately while being spaced apart from each other, in addition to the effect of the sipe end edge, a primary sipe extending parallel to the tire width direction is used. Since the edge effect in the front-rear direction of the vehicle, that is, in the tire circumferential direction, is enhanced, the braking performance and the acceleration performance, which are front-rear performances on an icy and snowy road surface, are improved. Further, the secondary sipe extending at an angle to the tire width direction enhances the edge effect in the lateral direction of the vehicle, that is, in the tire width direction, so that the turning performance on an icy and snowy road surface is also improved.

[Brief description of the drawings]

FIG. 1 is a front view of an entire tire showing an embodiment of a pneumatic radial tire according to the present invention.

FIG. 2 is a partially enlarged view of a tread pattern in a region between AA ′ and BB ′ in FIG. 1;

FIG. 3 is a partially enlarged view further enlarging a region C in FIG. 2;

FIG. 4 is an enlarged schematic plan view of a main part showing a block of a conventional tire.

FIG. 5 is an enlarged schematic plan view of a main part conceptually showing a block in which a tertiary sipe is formed.

[Explanation of symbols]

 Reference Signs List 1 tire tread portion 2 block 2A block row in central area 2a block 2B block row in middle area 2b block 2C block row in shoulder area 2c block 3 sipe 3a primary sipe 3b secondary sipe 3c tertiary sipe 4 circumferential groove 9 minimum Separation area 10 Maximum separation area

Claims (7)

[Claims] 1. A pneumatic radial tire having a block provided with a plurality of sipes extending in a tire width direction on a tire tread surface portion, wherein all or a part of the blocks have different angles in the tire circumferential direction at different angles within the same block. A pneumatic radial tire, wherein a primary sipe and a secondary sipe extending in the tire width direction while being separated from each other are regularly formed. 2. The primary sipe is a parallel sipe extending parallel to the tire width direction, and the secondary sipe is an inclined sipe extending at an angle to the tire width direction. The pneumatic radial tire according to claim 1, wherein the next sipes are alternately formed adjacent to each other. 3. The pneumatic radial tire according to claim 2, wherein a tertiary sipe is formed in a maximum separation region among a minimum separation region and a maximum separation region between the primary sipe and the secondary sipe. 4. The pneumatic radial tire according to claim 3, wherein the tertiary sipe is a single-sided open sipe extending in parallel with the secondary sipe, and only one side is open to the tire circumferential groove. 5. The minimum separation distance A between the primary sipe and the secondary sipe is defined as follows, where X is the separation distance between the primary sipe.
5. The pneumatic radial tire according to claim 2, wherein A = 0.2X to 0.4X. 6. The maximum separation distance B between the primary sipe and the tertiary sipe is B = 0.3X to 0.45X with respect to the separation distance X between the primary sipe described in claim 5. The pneumatic radial tire according to claim 3 or 4. 7. A block row of a central area partitioned and arranged by a circumferential groove in a central area of a tire tread portion, and a block row of an intermediate area located on both sides in the tire width direction.
The primary sipe and the secondary sipe according to claim 1, further comprising a shoulder area block row located on both sides in the tire width direction, and a block in the middle area block row and / or a block in the shoulder area block row. The pneumatic radial tire according to any one of claims 1 to 6, wherein a sipe is formed.