JP2020044983A - tire - Google Patents

Abstract

To provide a tire capable of offering great on-ice traction while exhibiting excellent uneven wear-resistant performance.SOLUTION: The tire includes a tread part. The tread part is provided with sipes 10. The sipes 10 include a portion in which repeating elements 11 continue in a longitudinal direction of the sipes 10. Each of the repeating elements 11 zigzags so that four sipe pieces 12 form an acute angle with each other. The four sipe pieces 12 include: a first sipe piece 12a extending at an angle of ±5° relative to the tire axial direction; a second sipe piece 12b extending inclined in continuity from the first sipe piece 12a; a third sipe piece 12c extending in continuity from the second piece 12b at an angle of ±5° relative to the tire axial direction; and a fourth sipe piece 12d continuing from the third piece 12c and extending inclined in the first axial direction toward a second circumferential direction opposite to a first circumferential direction. The length of the fourth sipe piece 12d is longer than that of the second sipe piece 12c.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a tire provided with a sipe in a tread portion.

  Tires on the premise of running on slippery roads such as on ice tend to have a sipe in the tread portion. The sipe provides a large frictional force in a direction orthogonal to its length. Therefore, in order to increase traction on ice, it is desirable that the sipes are arranged at an angle close to being parallel to the tire axial direction. As a related technique, there is Patent Document 1 below.

JP 2018-001803 A

  Generally, a sipe extending in the tire axial direction tends to greatly open when it goes out of the tread portion from the ground contact surface with the rotation of the tire. Such opening of the sipe has a problem that the amount of slip between the edge of the sipe and the road surface is increased, and thus uneven wear near the edge (for example, heel and toe wear) is caused.

  The present invention has been devised in view of the above problems, and has as its main object to provide a tire capable of providing great traction on ice while exhibiting excellent uneven wear resistance.

  The present invention is a tire including a tread portion, wherein the tread portion is provided with a sipe, the sipe includes a portion where a repeating element is continuous in a longitudinal direction of the sipe, and each of the repeating elements is The four sipe pieces are bent so as to form an acute angle with each other, and the four sipe pieces are connected to the first sipe piece extending at an angle of ± 5 ° with respect to the tire axial direction. And a second sipe piece extending obliquely in the first axial direction toward the first circumferential direction, and the first axial direction connected to the second sipe piece at an angle of ± 5 ° with respect to the tire axial direction. A third sipe piece extending in the second axial direction on the opposite side; and a third sipe piece connected to the third sipe piece and inclined in the first axial direction in a second circumferential direction opposite to the first circumferential direction. And the fourth sipe piece that extends Wherein the length of said fourth sipe piece is greater than the length of the second sipes piece.

  In the tire of the present invention, it is preferable that the fourth sipe piece extends to a side in the second circumferential direction from a region where the first sipe piece extends in the second axial direction.

  In the tire of the present invention, each of the first sipe piece and the third sipe piece preferably extends at an angle of 0 ° with respect to the tire axial direction.

  In the tire of the present invention, it is desirable that the length of the fourth sipe piece is 1.10 to 1.50 times the length of the second sipe piece.

  In the tire of the present invention, it is preferable that each of the four sipe pieces extends in a zigzag shape in a cross section orthogonal to the length direction.

  The sipe provided on the tread portion of the tire of the present invention includes a portion where the repeating elements are continuous in the longitudinal direction of the sipe. Each of the repeating elements is bent such that the four sipe pieces form an acute angle with each other. Further, the four sipe pieces extend at an angle of ± 5 ° with respect to the tire axial direction, and extend obliquely in the first axial direction toward the first circumferential direction following the first sipe piece. A second sipe piece, a third sipe piece connected to the second sipe piece and extending toward the second axial direction opposite to the first axial direction at an angle of ± 5 ° with respect to the tire axial direction; And a fourth sipe piece connected to the three sipe pieces and inclined in the first axial direction toward the second circumferential direction opposite to the first circumferential direction.

  Since the first and third sipe pieces extend at an angle of ± 5 ° in the tire axial direction, such a repetitive element provides a large frictional force in the tire circumferential direction when traveling on ice, and thus provides traction on ice. Can be increased. Further, when a shearing force in the circumferential direction of the tire acts on the repeating element, the sipe walls facing each other in the second sipe piece and the fourth sipe piece come into contact with each other, and as a result, the first sipe piece and the third sipe piece become excessively strong. Opening can be suppressed. Such an action reduces the amount of slip between the edges of the first sipe piece and the third sipe piece when the edges of the first sipe piece and the third sipe piece come out of the contact surface of the tread portion with the rotation of the tire. Therefore, uneven wear near the edge is suppressed.

  In the present invention, the length of the fourth sipe piece is larger than the length of the second sipe piece. Therefore, when a shearing force is applied, the repetitive element can cause torsional deformation to strongly press the sipe walls of the second sipe piece and / or the fourth sipe piece. By this action, the opening of the first sipe piece and the third sipe piece can be further suppressed.

  As described above, the tire of the present invention can provide great traction on ice while exhibiting excellent uneven wear resistance.

It is a cross section of a tread part of a tire of this embodiment. It is an enlarged plan view of the land part of FIG. (A) is an enlarged view of the repeating element of the sipe, and (B) is an enlarged view of the repeating element when the sipe is opened. FIG. 3A is a cross-sectional view taken along line AA of FIG. 3A, and FIG. 3B is a cross-sectional view of the sipe piece having the cross section shown in FIG. (A) is an enlarged view of a sipe repeating element of Comparative Example 1, and (B) is an enlarged view of a sipe repeating element of Comparative Example 2.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a cross-sectional view of a tread portion 2 of a tire 1 of the present embodiment. FIG. 1 is a meridian sectional view including a tire rotation axis in a normal state of the tire 1. The tire 1 of the present embodiment is suitably used, for example, as a pneumatic tire for a passenger car. However, the present invention is not limited to such an embodiment, and the tire 1 of the present invention may be used, for example, for heavy loads.

  The “normal state” is a no-load state in which the tire is assembled to the normal rim and the normal internal pressure is filled. Hereinafter, unless otherwise specified, dimensions and the like of each part of the tire are values measured in this normal state.

  “Regular rim” is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, “standard rim” for JATMA, “Design Rim” for TRA, For ETRTO, it is "Measuring Rim".

  "Normal internal pressure" is the air pressure specified for each tire in the standard system including the standard on which the tire is based. For JATMA, the "maximum air pressure" and for TRA, the table "TIRE LOAD LIMITS AT The maximum value described in "VARIOUS COLD INFLATION PRESSURES" is "INFLATION PRESSURE" for ETRTO.

  As shown in FIG. 1, the tread portion 2 is provided with, for example, a plurality of main grooves 3 extending continuously in the tire circumferential direction and land portions 4 divided into these.

  FIG. 2 shows an enlarged plan view of the land portion 4. As shown in FIG. 2, the land portion 4 of the present embodiment is configured as, for example, a block row including a plurality of blocks 6 in the tire circumferential direction. The block 6 is partitioned between a plurality of lateral grooves 5 that cross the land portion 4 in the tire axial direction.

  The lateral groove 5 extends linearly, for example, inclined with respect to the tire axial direction. Thereby, the lateral edge 6a of the block 6 is inclined with respect to the tire axial direction.

  A sipe 10 is provided on the ground surface of the tread portion 2. In this embodiment, a plurality of sipes 10 are provided in one block 6. However, the present invention is not limited to such a block, as long as the sipe 10 is arranged on the ground surface of the tread portion 2. As used herein, “sipe” refers to a notch having a width of less than 1.5 mm. More preferably, the width of the sipe 10 is, for example, 0.5 to 1.0 mm.

  The sipe 10 includes a portion where the repeating element 11 is continuous in the longitudinal direction of the sipe 10. Each of the repeating elements 11 is bent such that the four sipe pieces 12 form an acute angle with each other. Further, the four sipe pieces 12 include a first sipe piece 12a, a second sipe piece 12b, a third sipe piece 12c, and a fourth sipe piece 12d.

  FIG. 3A shows an enlarged view of the repeating element 11. As shown in FIG. 3A, the first sipe piece 12a extends at an angle of ± 5 ° with respect to the tire axial direction. The second sipe piece 12b is connected to the first sipe piece 12a and extends obliquely in the first axial direction toward the first circumferential direction. In each drawing of this specification, the first circumferential direction is an upward direction, and the second circumferential direction on the opposite side is a downward direction. The first axis direction is the left direction, and the second axis direction on the opposite side is the right direction.

  The third sipe piece 12c is continuous with the second sipe piece 12b and extends toward the second axial direction at an angle of ± 5 ° with respect to the tire axial direction. The fourth sipe piece 12d is continuous with the third sipe piece 12c and extends obliquely in the first axial direction toward the second circumferential direction.

  Since the first sipe piece 12a and the third sipe piece 12c extend at an angle of ± 5 ° in the tire axial direction, the repeating element 11 of the present invention provides a large frictional force in the tire circumferential direction when traveling on ice, Thus, traction on ice can be increased.

  In order to surely increase traction on ice, each of the first sipe piece 12a and the third sipe piece 12c preferably extends at an angle of ± 3 ° with respect to the tire axial direction. As a more desirable aspect, each of the first sipe piece 12a and the third sipe piece 12c of the present embodiment extends at an angle of 0 ° with respect to the tire axial direction.

  FIG. 3B is an enlarged view of the repeating element 11 when the sipe 10 is opened. Note that the opening of the sipe 10 is colored in FIG. 3B so that the invention can be easily understood. As shown in FIG. 3 (B), when the shearing force in the tire circumferential direction acts on the repeating element 11, the sipe walls facing each other in the second sipe piece 12b and the fourth sipe piece 12d come into contact with each other, and as a result, Excessive opening of the first sipe piece 12a and the third sipe piece 12c can be suppressed. Such an action reduces the amount of slip between the edge of the first sipe piece 12a and the edge of the third sipe piece 12c when the edges of the first sipe piece 12a and the third sipe piece 12c come out of the contact surface of the tread portion 2 with the rotation of the tire. Let it. Therefore, uneven wear near the edge is suppressed.

  As shown in FIG. 3A, in the present invention, the length L4 of the fourth sipe piece 12d is larger than the length L2 of the second sipe piece 12b. Therefore, when a shear force acts on the repeating element 11, the amount of shear deformation along the sipe wall of the fourth sipe piece 12d tends to be larger than the amount of shear deformation along the sipe wall of the second sipe piece 12b. . Therefore, the second sipe piece 12b, the fourth sipe piece 12d, and the land piece 13 therebetween have a tendency to undergo torsional deformation when a contact pressure is applied. For this reason, the sipe walls of the second sipe piece 12b and / or the fourth sipe piece 12d can be pressed strongly. By this action, the opening of the first sipe piece 12a and the third sipe piece 12c can be further suppressed.

  To ensure traction on ice, the length L2 of the second sipe piece 12b is preferably smaller than the length L1 of the first sipe piece 12a and the length L3 of the third sipe piece 12c. Similarly, the length L4 of the fourth sipe piece 12d is desirably smaller than the length L1 of the first sipe piece 12a and the length L3 of the third sipe piece 12c. In this specification, it is desirable that the length of each sipe piece is measured, for example, at the center line of the sipe.

  The fourth sipe piece 12d extends to the side in the second circumferential direction from a region in which the first sipe piece 12a continuous via the second sipe piece 12b and the third sipe piece 12c extends in the second axial direction. desirable. As a result, the end of the fourth sipe piece 12d on the second circumferential direction is located on the second circumferential direction side of the first sipe piece 12a. The sipe 10 having a plurality of such repetitive elements 11 can be arranged obliquely according to, for example, the shape of the block while securing the axial component in the tire by the first sipe piece 12a and the third sipe piece 12c. . Therefore, the sipe of the present invention can provide a large traction on ice even when the sipe is arranged diagonally.

  The length L4 of the fourth sipe piece 12d is preferably not less than 1.10 times, more preferably not less than 1.20 times, and more preferably not more than 1.50 times the length L2 of the second sipe piece 12b. Is 1.40 times or less. The repeating element 11 having the fourth sipe piece 12d can increase the arrangement angle of the entire sipe with respect to the tire axial direction while securing traction on ice.

  In the present embodiment, the acute angle portions 14 formed by the four sipe pieces 12 are arranged, for example, at the same angle as each other. However, the present invention is not limited to such an embodiment, and the acute angle portions 14 may have different angles. The angle θ1 of the acute angle portion 14 is desirably, for example, 45 ° or more. Specifically, the angle θ1 of the acute angle portion 14 is desirably 50 to 80 °. Such a repeating element 11 can secure an appropriate distance in the tire circumferential direction between the first sipe piece 12a and the third sipe piece 12c while exhibiting the above-described effects, and can further improve the uneven wear resistance performance. .

  As shown in FIG. 2, the arrangement angle of the sipe 10 is desirably, for example, 5 to 15 degrees. Such a sipe 10 can provide a large frictional force in the tire circumferential direction. Note that the arrangement angle of the sipe 10 corresponds to an angle with respect to the tire axial direction of a straight line connecting one end of the first sipe pieces 12a adjacent in the tire axial direction.

  FIG. 4A is a cross-sectional view taken along line AA of FIG. FIG. 4A is a diagram showing a cross section orthogonal to the length direction of each sipe piece 12. As shown in FIG. 4A, each of the four sipe pieces 12 desirably extends in a zigzag shape in the tire radial direction in a cross section orthogonal to the length direction.

  FIG. 4B is a cross-sectional view of the sipe piece 12 having the cross section shown in FIG. As shown in FIG. 4 (B), when a load is applied in the tire radial direction and in the tire circumferential direction, the sipe pieces 12 having the above-mentioned cross-sectional shape contact with each other and mutually support the sipe walls. By this action, deformation of the block is suppressed, and excellent steering stability is obtained. The sipe having such a shape can be vulcanized and formed by a known method using a vulcanization mold having a sipe blade extending in a zigzag shape in the depth direction of the sipe.

  In the sipe piece 12 having the above-described cross-sectional shape, the maximum width of the zigzag amplitude is preferably, for example, 2.0 to 3.0 times the opening width of the sipe. Thereby, at the time of vulcanization molding, damage to the tread rubber when pulling out the sipe blade is suppressed.

  As mentioned above, although the tire of one embodiment of the present invention was explained in detail, the present invention is not limited to the above-mentioned specific embodiment, but can be carried out in various modes.

A pneumatic tire of size 185 / 65R15 having the above-mentioned sipes was prototyped based on the specifications in Table 1. As Comparative Example 1, a tire having a sipe a including a plurality of repeating elements b shown in FIG. In the repeating element b shown in FIG. 5A, each sipe piece c is bent so as to form an obtuse angle with each other and extends in a trapezoidal wave shape. As Comparative Example 2, a tire having a sipe d shown in FIG. In the sipe d, the first sipe piece e and the third sipe piece g are inclined at about 7 ° with respect to the tire axial direction, and the second sipe piece f and the fourth sipe piece h have the same length. doing. Each test tire has substantially the same configuration except for the shape of the sipe. Each test tire was tested for traction on ice, uneven wear resistance, and steering stability on dry road surfaces. The common specifications and test methods for each test tire are as follows.
Mounting rim: 15 × 6.0J
Tire pressure: front wheel 220 kPa, rear wheel 210 kPa
Test vehicle: 1300cc displacement, front wheel drive vehicle Tire mounting position: all wheels

<Traction on ice>
The traction on ice when traveling on an icy road with the test vehicle equipped with each test tire was evaluated by the sensory sense of the driver. The results are scores with the traction on ice of Comparative Example 1 being 100, and the larger the numerical value, the better the traction on ice.

<Partial wear resistance>
A wear energy measuring device was used to measure the wear energy at the edge of the sipe of each test tire. The result is an index with the reciprocal of the wear energy of Comparative Example 1 being 100. The larger the value, the smaller the wear energy and the better the uneven wear resistance.

<Driving stability on dry roads>
The steering stability when traveling on a dry road surface with the test vehicle was evaluated based on the driver's sensuality. The results are scored with the comparative example taken as 100, and the larger the numerical value, the better the steering stability.
The results of the test are shown in Table 1.

  As a result of the test, it was confirmed that the tire of the example provided great traction on ice while exhibiting excellent uneven wear resistance. In addition, it was confirmed that the tires of the examples exhibited a steering stability equal to or higher than that of the comparative example on a dry road surface.

2 Tread part 10 Sipe 11 Repeat element 12 Sipe piece 12a First sipe piece 12b Second sipe piece 12c Third sipe piece 12d Fourth sipe piece

Claims (5)

A tire including a tread portion,
A sipe is provided in the tread portion,
The sipe includes a portion where a repeating element is continuous in a longitudinal direction of the sipe,
Each of said repeating elements is bent such that four sipe pieces form an acute angle with each other;
The four sipe pieces are
A first sipe piece extending at an angle of ± 5 ° with respect to the tire axial direction;
A second sipe piece connected to the first sipe piece and extending obliquely in a first axial direction toward a first circumferential direction;
A third sipe piece connected to the second sipe piece and extending toward the second axis direction opposite to the first axis direction at an angle of ± 5 ° with respect to the tire axis direction;
A fourth sipe piece connected to the third sipe piece and extending obliquely in the first axial direction toward a second circumferential direction opposite to the first circumferential direction,
The length of the fourth sipe piece is greater than the length of the second sipe piece,
tire.   The tire according to claim 1, wherein the fourth sipe piece extends to a side in the second circumferential direction from a region where the first sipe piece extends in the second axial direction.   3. The tire according to claim 1, wherein each of the first sipe piece and the third sipe piece extends at an angle of 0 ° with respect to the tire axial direction. 4.   The tire according to any one of claims 1 to 3, wherein the length of the fourth sipe piece is 1.10 to 1.50 times the length of the second sipe piece.   The tire according to any one of claims 1 to 4, wherein each of the four sipe pieces extends in a zigzag shape in a cross section orthogonal to a length direction thereof.

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