JP2014108665A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire having a tread pattern in which snow traction performance is secured and snow handling performance can be improved.SOLUTION: In a pneumatic tire 10 having a tread pattern which includes a main groove 12 mounted at the tire center part and extending in the tire circular direction, and a center block 15a, a shoulder block 15b and an intermediate block 15c mounted in both sides of the tire width direction of the main groove 12 respectively, each siping 16a to 16c is formed so that the siping angle θof a siping 16a formed at the center block 15a is larger than the siping angle θof a siping 16b formed at the shoulder block 15b, and the siping angle θof a siping 16c formed at the intermediate center block 15c is larger than the center siping angle θ.

Description

  The present invention relates to a pneumatic tire having sipes formed on a block, and more particularly to a pneumatic tire excellent in steering stability performance on a snowy road surface.

Conventionally, in a stud lesbian tire, sipes extending in a direction intersecting the tire circumferential direction are uniformly arranged on the land portion of the tread. This is because the sipe opens and closes when the land part of the tread contacts the tire tread, and the straight and braking performance on the snowy and icy road surfaces is ensured by the scratching effect (edge effect) and the snow biting effect on the snowy road surface. It is to do.
In addition, in order to improve the contact performance by making the contact pressure at the land portion uniform, a three-dimensional sipe with unevenness in the depth direction is provided at the center in the tire width direction, and unevenness in the depth direction is provided at both ends in the tire width direction. A method of providing a two-dimensional sipe without a sipe (for example, refer to Patent Document 1), or a method of increasing the amplitude of a sipe to reduce the heel and toe wear on the block stepping side and decreasing on the kicking side ( For example, Patent Document 2) has been proposed.

Japanese Patent No. 4325948 JP 2009-196442 A

By the way, in a tire having a rug-based tread pattern, the amount of edge of the component in the front-rear direction is increased, so the traction performance on snow is improved, but the edge component in the lateral direction is reduced accordingly, so the handling performance on snow is reduced. There was a problem such as.
However, since the sipe described in Patent Document 1 extends in a direction parallel to the tire width direction, the edge component in the lateral direction cannot be increased. On the other hand, in the sipe described in Patent Document 2, although the extension direction intersects with the tire width direction, the extension direction intersects with the tire width direction up to the sipe of the shoulder portion having less influence on the snow handling performance. There was a problem that the traction performance deteriorated.

  The present invention has been made in view of the conventional problems, and an object of the present invention is to provide a pneumatic tire having a tread pattern that can improve snow handling characteristics while ensuring snow traction characteristics.

The present invention includes a main groove that is located at the center of the tire tread surface in the tire width direction and extends along the tire circumferential direction, a lug groove that extends in a direction intersecting the main groove, the main groove, and the lug A plurality of land portions defined by the grooves are divided into a center block located on the main groove side, a shoulder block located on the outer side in the tire width direction, and an intermediate block located between the center block and the shoulder block. And a plurality of sipes formed in each of the blocks, and a center sipe angle that is an angle with respect to a tire width direction of the sipe formed in the center block is the shoulder. The sipe formed in the block is larger than the shoulder sipe angle that is an angle with respect to the tire width direction, and formed in the intermediate block. Intermediate sipe angle is an angle with respect to the tire width direction of the sipe which is, and greater than the center sipes angle.
In this way, the sipe angle of the sipe formed on the shoulder block that has little influence on the snow handling performance is reduced to secure the edge component in the front-rear direction, and the sipe angle of the sipe formed on the center block and the intermediate block is increased. Since the edge component in the lateral direction is increased and the followability of the center block and the intermediate block in the state where the slip angle is given in handling traveling is improved, the handling performance on snow can be improved.
Moreover, since the sipe angle of the sipe formed in the center block is smaller than the sipe angle of the sipe formed in the intermediate block, sufficient traction performance on snow can be ensured.

Further, according to the present invention, the position of the intersection of a straight line obtained by extending a sipe formed on the center block to the intermediate block side and a straight line obtained by extending a sipe formed on the intermediate block to the center block side is the center block. And a straight line extending the sipe formed on the intermediate block to the shoulder block side and a straight line extending the sipe formed on the shoulder block to the intermediate block side The position of the intersection is in a longitudinal groove that divides the intermediate block and the shoulder block.
As a result, the sipe edge pressures on the tire treads are connected uniformly and work, so that the blocks do not behave locally unstable in the tire treads, and stable snow performance can be realized.

The present invention is characterized in that the intermediate sipe angle is three times as large as the center sipe angle.
Thereby, sufficient snow traction performance can be secured while securing snow handling performance.

In the present invention, the size of the center sipe angle is in the range of 3 ° to 8 °, the size of the intermediate sipe angle is in the range of 9 ° to 24 °, and the size of the shoulder sipe angle is It is 0 degree.
By setting the center sipe angle, the intermediate sipe angle, and the shoulder sipe angle as described above, a pneumatic tire excellent in both snow handling performance and snow traction performance can be obtained.
In the present invention, the lug groove extends from one end in the tire width direction so as to intersect in the tire circumferential direction toward the center in the tire width direction, and is folded back at the center in the tire width direction. It is a V-shaped lug groove extending to the other end in the direction.
Thereby, since the grip force in the front-rear direction and the snow column shear force on the snow can be ensured, the snow handling characteristics and the snow traction characteristics can be further improved.

  The summary of the invention does not list all necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

It is a figure which shows the tread pattern of the pneumatic tire which concerns on this Embodiment. It is a figure which shows the sipe angle of each block. It is a figure which shows the other example of the tread pattern of the pneumatic tire by this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an example of a tread pattern of a pneumatic tire (hereinafter referred to as a tire) 10 according to the present embodiment, in which the vertical direction is the tire circumferential direction and the horizontal direction is the tire width direction.
In the figure, 11 is a tread, 12 is a circumferential groove (hereinafter referred to as a main groove) provided to extend along the tire circumferential direction at the center of the tread 11 on the tread surface side, and 13 is a main groove 12. The lug grooves 14a and 14b that extend along the direction intersecting with the main groove 12 and communicate with the main groove 12 extend in the direction intersecting the lug groove 13 (here, the direction inclined about 10 ° with respect to the tire circumferential direction). Longitudinal grooves 16a to 16c that divide the land portion 15 partitioned by the main groove 12 and the lug groove 13 into a center block 15a, a shoulder block 15b, and an intermediate block 15c, and are provided on the tire tread side of each block 15a to 15c. It is a sipe.
Hereinafter, the vertical groove 14a located on the main groove 12 side is referred to as an inner vertical groove.
The center block 15a is a block defined by the main groove 12, the lug groove 13, and the inner vertical groove 14a, the shoulder block 15b is a block defined by the outer vertical groove 14b and the lug groove 13, and the intermediate block 15c is an inner vertical groove. 14a is a block defined by the lug groove 13 and the outer vertical groove 14b.

Each of the two groove walls of the lug groove 13 is formed of an arc whose distance gradually increases from the main groove 12 side toward the outer side in the tire width direction. That is, the groove width of the lug groove 13 is formed so as to gradually increase from the main groove 12 side toward the outer side in the tire width direction. Further, the right lug groove of the main groove 12 extends upward as it goes from the main groove 12 toward the outer side in the tire width direction, and the left lug groove extends upward to the left.
Thus, if the groove width of the lug groove 13 is formed so as to increase toward the outer side in the tire width direction, the block length can be increased at the center portion of the tire to ensure block rigidity, and the center portion at the shoulder portion. Therefore, it is possible to increase the shearing force in the snow due to the lacking lug groove 13, so that the handling characteristics on snow and the traction characteristics on snow can be further improved.
Moreover, in this example, while making the groove width of the vertical grooves 14a and 14b which divide the land part 15 into block 15a-15c narrower than the groove width of the main groove 12, the groove width of the lug groove 13 is made into the main groove 12 side. Since it forms so that it may gradually become wide as it goes to a tire width direction outer side from, it can improve drainage.
Furthermore, in this example, the sum of the cross-sectional area of the main groove 12 that is a vertical groove and the cross-sectional areas of the vertical grooves 14a and 14b is made smaller than the total cross-sectional area of the lug groove 13 that is a horizontal groove. Thereby, since the ratio of the lug groove 13 can be increased as compared with the tire having the conventional tread pattern at the same negative rate (groove area ratio), the longitudinal force on the snow can be effectively ensured.

In this example, the size of the sipe angle (the angle formed between the sipe extension direction and the tire width direction) of the sipe 16a to 16c formed in each of the blocks 15a to 15c is different for each block 15a to 15c. Therefore, the snow handling characteristics are improved while ensuring the snow traction characteristics.
Specifically, as shown in FIG. 2, the center sipe angle that is the sipe angle of the sipe 16a formed in the center block 15a is θ _A = 5 °, and the sipe angle of the sipe 16b formed in the shoulder block 15b is A shoulder sipe angle is set to θ _B = 0 °, and an intermediate sipe angle that is a sipe angle of the sipe 16c formed in the intermediate block 15c is set to θ _C = 15 °.

In order to improve the traction performance on snow, it is preferable that the sipe angle is 0 °, that is, the sipe extension direction is parallel to the tire width direction because the edge component in the front-rear direction increases. On the other hand, in handling traveling on snow with a slip angle applied, a larger sipe angle is preferable because an edge component in the lateral direction increases.
In this example, the sipe angles θ _A and θ _C of the sipes 16a and 16c formed in the center block 15a and the intermediate block 15c that greatly contribute to the handling performance are increased to increase the edge component in the lateral direction and to the handling performance. By setting the sipe angle θ _B of the sipe 16b formed on the shoulder block 15b having little influence to 0 °, the followability to the road surface at the tire center portion and the middle portion of the tire is improved, and an edge component in the front-rear direction is secured. I am doing so.
Since the center block 15a has a great influence on the snow traction performance, in this example, the sipe angle θ _A of the sipe 16a formed in the center block 15a is smaller than the sipe angle θ _C of the sipe formed in the intermediate block. doing.
Thus, the center block 15a, the shoulder block 15b, and, when forming each sipe 16a~16c the intermediate block 15c, the center sipes angle theta _A larger than the shoulder sipe angle theta _B, and intermediate sipe angle If the tire 10 in which θ _C is larger than the center sipe angle θ _A is used, it is possible to improve the snow handling performance while ensuring the snow traction performance of the vehicle.
At this time, if the size of the intermediate sipe angle θ _C is about three times the size of the center sipe angle θ _A , the on-snow traction performance and on-snow handling performance of the vehicle can be improved in a balanced manner.

  In this example, as shown in FIG. 2, the position of the intersection of the straight line extending the sipe 16a to the intermediate block 15c side and the straight line extending the sipe 16c to the center block 15a side is in the inner longitudinal groove 14a. Since the sipes 16a to 16c are formed so that the position of the intersection of the straight line extending the sipe 16c toward the shoulder block 15b and the straight line extending the sipe 16b toward the intermediate block 15c is in the outer longitudinal groove 14b, the tire tread Because the sipe edge pressure in the yard works evenly in a single line, the blocks do not behave locally unstable in the tire tread, and stable on-snow performance can be realized.

In the above embodiment, the center sipe angle is θ _A = 5 °, the shoulder sipe angle is θ _B = 0 °, and the intermediate sipe angle is θ _C = 15 °. However, the present invention is not limited to this. . The center sipe angle θ _A is preferably in the range of 3 ° to 8 °, and the intermediate sipe angle θ _C is preferably in the range of 9 ° to 24 °. Note that the shoulder sipe angle θ _B is not necessarily 0 °, and may be a value smaller than the center sipe angle θ _A.
By setting the center sipe angle θ _A , the shoulder sipe angle θ _B , and the intermediate sipe angle θ _C within the above ranges, it is possible to improve snow handling performance while ensuring snow traction performance.

In the above example, the sipes 16a to 16c are linear sipes, but they may be wavy or polygonal sipes.
Further, the sipe 16a to 16c may be a two-dimensional sipe having no unevenness in the depth direction or a three-dimensional sipe having an unevenness in the depth direction. Alternatively, a two-dimensional sipe may be used as a base tone, and a part thereof may be a three-dimensional sipe.
In the above example, the inner vertical groove 14a and the outer vertical groove 14b are narrow grooves. However, either or both of the inner vertical groove 14a and the outer vertical groove 14b have the same groove width as that of the main groove 12. Good.
In addition, the extending direction of the inner vertical groove 14a and the outer vertical groove 14b is a direction inclined by about 10 ° with respect to the tire circumferential direction, but is not limited thereto, and may be a direction parallel to the tire circumferential direction. The direction may be inclined with respect to the circumferential direction. However, from the viewpoint of block rigidity, the magnitude of the inclination is preferably within 30 ° with respect to the tire circumferential direction.

Further, in the above example, the main groove 12 is a straight groove, and the extending direction of the vertical grooves 14a and 14b is a vertical groove slightly inclined with respect to the tire circumferential direction. However, as shown in FIG. It may be a straight groove.
In the tread pattern of FIG. 3, the main groove 12, the inner vertical groove 24 a and the outer vertical groove 14 b are narrow grooves, and the inner vertical groove 24 a is wider than the main groove 12. Thereby, the drainage effect in the circumferential direction can be further enhanced.
Similarly to the above example, if the sum of the cross-sectional area of the main groove 12 as the vertical groove and the cross-sectional area of the vertical grooves 24a and 14b is made smaller than the total cross-sectional area of the lug groove 13 as the horizontal groove, the same. Since the ratio of the lug grooves 13 can be increased as compared with a tire having a conventional tread pattern at a negative rate (groove area ratio), the longitudinal force on the snow can be effectively ensured.

雪上トラクション性能は、試験車両を車速５km/hで雪上を走行した後、アクセルを踏んで加速し車速が４０km/hに到達するのに要する時間(加速時間)を測定し、この加速時間の逆数を従来例を１００とした指数で評価した。数字が高い程加速時間が短く、雪上トラクション性能が高い。
雪上ハンドリング性能は、トラック状のテストコースを車速が６０km/hで１０周したときのトラック一周当たりに要する (ＬＡＰタイム)を測定し、このＬＡＰタイムの逆数を従来例１を１００とした指数で評価した。数字が高い程ＬＡＰタイムが短く、雪上ハンドリング性能が高い。 The tire shown in FIG. 1 has a shoulder sipe angle of 0 °, an intermediate sipe angle of 15 °, and a center sipe angle of 5 ° (invention), and a conventional tire in which all blocks have a sipe angle of 0 ° (see FIG. Table 1 below shows the results obtained by preparing a conventional example 1), carrying out a running test with each tire mounted on a test vehicle (Skoda Octavia), and evaluating snow traction performance and snow handling performance. For comparison, a tire having a sipe angle of 15 ° for all blocks (Comparative Example 1) and a tire having a shoulder sipe angle of 0 ° and an intermediate sipe angle and a center sipe angle of 15 ° (Comparative Example 2) The results of a similar test on a tire (Comparative Example 3) having a shoulder sipe angle and an intermediate sipe angle of 0 ° and a center sipe angle of 15 ° are also described.
The tire size of each tire is 195 / 65R15, the rim used is 15 × 6.5J, the internal pressure is 220kPa, and the load is (vehicle weight) + 70kg.

Snow traction performance is measured by measuring the time (acceleration time) required for the vehicle to reach 40 km / h by accelerating the accelerator by stepping on the accelerator after driving the test vehicle on the snow at a speed of 5 km / h. Was evaluated by an index with the conventional example as 100. The higher the number, the shorter the acceleration time and the higher the traction performance on snow.
The handling performance on the snow is an index with the LAP time measured as 10 times per track when the vehicle speed is 60 km / h on a track-like test course. evaluated. The higher the number, the shorter the LAP time and the better the snow handling performance.

As can be seen from Table 1, the tire of the present invention has a snow handling performance that is approximately 10% higher than that of the conventional example, while ensuring a snow traction performance substantially equivalent to that of the conventional tire.
On the other hand, in the tire of Comparative Example 1 in which the sipe angles of all the blocks were 15 °, it was confirmed that the snow traction performance was significantly lower than the conventional example, although the snow handling performance was improved. .
In addition, the tire of Comparative Example 2 in which the intermediate sipe angle and the center sipe angle are both 15 ° is improved in snow handling performance compared to the conventional tire, but is almost equivalent to the snow traction performance in the conventional example. Could not be secured.
On the other hand, the tire of Comparative Example 3 in which only the center sipe angle is 15 ° has substantially the same snow traction performance as that of the conventional tire and also has improved snow handling performance. By comparison, it can be seen that there is little improvement in handling performance on snow.
Therefore, it was confirmed by this test that by appropriately setting the sipe angle for each block, it is possible to effectively improve the snow handling performance while ensuring the snow traction performance.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the embodiment. It is apparent from the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  According to the present invention, the snow handling performance can be effectively improved while ensuring the snow traction performance, so that the running stability performance of the vehicle on the snowy road can be further improved.

10 pneumatic tires, 11 treads, 12 circumferential grooves (main grooves), 13 lug grooves,
14a inner longitudinal groove, 14b outer longitudinal groove, 15a center block,
15b Shoulder block, 15c Intermediate block, 16a-16c Sipe.

Claims (5)

A main groove located at the center of the tire tread surface in the tire width direction and extending along the tire circumferential direction, a lug groove extending in a direction crossing the main groove, and a partition formed by the main groove and the lug groove A plurality of vertical grooves that divide the land portion into a center block located on the main groove side, a shoulder block located on the outer side in the tire width direction, and an intermediate block located between the center block and the shoulder block; A pneumatic tire provided with a plurality of sipes formed in each of the blocks,
The center sipe angle that is an angle with respect to the tire width direction of the sipe formed in the center block is larger than the shoulder sipe angle that is an angle with respect to the tire width direction of the sipe formed in the shoulder block,
A pneumatic tire, wherein an intermediate sipe angle, which is an angle of a sipe formed in the intermediate block with respect to a tire width direction, is larger than the center sipe angle.   The position of the intersection of the straight line extending the sipe formed on the center block to the intermediate block side and the straight line extending the sipe formed on the intermediate block to the center block side is the center block and the intermediate block. The position of the intersection of the straight line extending in the longitudinal groove that divides the sipe formed in the intermediate block to the shoulder block side and the straight line formed in the shoulder block extending from the sipe formed in the shoulder block is The pneumatic tire according to claim 1, wherein the pneumatic tire is in a longitudinal groove that divides the intermediate block and the shoulder block.   The pneumatic tire according to claim 1 or 2, wherein the size of the intermediate sipe angle is three times the size of the center sipe angle. The size of the center sipe angle is in the range of 3 ° to 8 °;
The size of the intermediate sipe angle is in the range of 9 ° to 24 °;
The pneumatic tire according to any one of claims 1 to 3, wherein a size of the shoulder sipe angle is 0 °. The lug groove extends from one end in the tire width direction so as to intersect the tire circumferential direction toward the center in the tire width direction, and is folded back at the center in the tire width direction to be the other end in the tire width direction. The pneumatic tire according to any one of claims 1 to 4, wherein the pneumatic tire is a V-shaped lug groove extending up to a point.

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