JPH0825914A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To secure low passage noise and prevent partial wear by disposing at least one side face out of four side faces at a large angle to the land part surface in a land part with narrow block width compared to a land part with wide block width between two block flat parts adjacent to a lateral groove placed in between. CONSTITUTION:Black land part groups 11, 12 are partitioned into wide block land parts 8A, 9A, 10A with the same block width and different pitch ratios, and narrow block land parts 8B, 9B, 10B with the same narrow block width and different pitch ratios by circumferential grooves 3 and lateral grooves 6 extended across bent parts 5. In these block land parts 8A, 8B; 9A, 9B; 10A, 10B adjacent to lateral grooves 6a, 6b, 6c placed in between, at least one side face out of four side faces of each block land part in the narrow block land parts 8B, 9B, 10B is disposed at a large angle to the block land part surface in comparison to the wide block land parts 8A, 9A, 10A. Rigidity between the block land parts and in the block land parts is thereby uniformed so as to suppress partial wear.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a see-through peripheral groove having a groove wall portion which is bent at a predetermined pitch shorter than a tire ground contact length and alternately protrudes inward and outward in the tread width direction, and the peripheral groove. The present invention relates to a pneumatic tire formed by forming block land portions having different sizes by partitioning with a plurality of lateral grooves that extend across the bent portion of, and particularly, low passing noise which is an advantage of this tire. The present invention relates to a pneumatic tire in which uneven wear is suppressed while being secured.

[0002]

2. Description of the Related Art When a tire is provided with a circumferential groove extending along its circumference, the circumferential groove portion in the tire contact area forms a so-called tube, and air is introduced into the tube. Is trapped, this air vibrates and 700 to 1100H
A standing wave with a dominant frequency of z is generated, which causes passing noise.

In order to reduce this passing noise, it is sufficient to have a structure in which the vibration of the air that is trapped is attenuated. Therefore, the circumferential groove is bent at a predetermined pitch shorter than the tire ground contact length so as to move inward and outward in the tread width direction. It is preferable to have a configuration having groove wall portions that alternately project.

[0004]

However, in the case of a tire having a tread portion having a block pattern, bending the circumferential groove means that the block land portion group along the tire circumference has large and small block land portions having different block widths. Will inevitably consist of. The fact that the block widths are different means that the rigidity of the land portion is also different for each block land portion. This means, for example, if two block land portions adjacent to each other across the lateral groove and having different block widths are used, the tire load When rolling, when a block land portion with a long block width (hereinafter referred to as "wide block land portion") is followed by a block land portion with a short block width (hereinafter referred to as "narrow block land portion"), Due to the difference in rigidity of the land portion, the block land portion having a short block width is apt to be dragged, which easily wears the block land portion having a short block width. In addition, when focusing on one block land portion, the ground contact protruding portion tends to be dragged, and thus is more easily worn.

Therefore, an object of the present invention is to make the rigidity between two block land portions adjacent to each other across a lateral groove different in block width and within each block land portion uniform so that the tread portion having the circumferential groove is provided. Another object of the present invention is to provide a pneumatic tire in which uneven wear is less likely to occur while ensuring low passage noise, which is an advantage of.

[0006]

In order to achieve the above-mentioned object, the present invention provides a tread portion with groove wall portions which are bent at a predetermined pitch shorter than the tire ground contact length and alternately project inward and outward in the tread width direction. By dividing with the circumferential groove having and a plurality of lateral grooves extending across the bent portion of the circumferential groove,
In a pneumatic tire formed by forming block land portions of different sizes, two narrow block land portions adjacent to each other across the lateral groove have different block widths, and the narrow block land portion is larger than the wide block land portion. The pneumatic tire is characterized in that at least one of the four side surfaces of the block land portion is arranged at a large angle with respect to the surface of the block land portion. In addition, a one-sided opening lateral sipe that extends from the circumferential groove in the block width direction and terminates in the land part is provided in the block land part. It is preferable to increase the sipe volume of the lateral sipe. The sipe volume here means the product of the sipe length, the sipe depth, and the sipe width.

A tread pattern of a typical pneumatic tire according to the present invention is shown in FIG. 1, and a partially enlarged view of this pattern is shown in FIG. 2, in which 1 is a tread portion, 2 is a tread width direction, and 3 is a tread pattern. Circumferential groove, 4 is a groove wall portion of the peripheral groove, 5 is a bent portion of the peripheral groove, 6 is a lateral groove, 7 is one end open lateral sipe, 8A,
9A and 10A are wide block land portions, and 8B, 9B,
10B is a narrow block land portion, and 11 and 12 are shoulder side block land portions. The pneumatic tire shown in FIG. 1 includes a tread portion 1, two circumferential grooves 3 that are bent at a predetermined pitch shorter than a tire contact length, and have groove wall portions 4 that alternately project inward and outward in a tread width direction 2. By dividing the circumferential groove 3 into a plurality of lateral grooves 6 extending across the bent portion 5, the block land portion groups 11 and 12 on both shoulder sides.
The block land parts 8A, 8B, 9A, 9 of different sizes.
B, 10A, and 10B. In this figure, the block land portions 11 and 12 are respectively divided into six types of block land portions 8A, 8B, 9A and 9 of different sizes.
B, 10A, 10B, specifically, three types of wide block land portions 8A, 9A, 10A having the same block width but different pitches, and these block land portions 8A,
3 types of narrow block land portions 8B, 9B and 10B having the same block width shorter than 9A and 10A and different pitches
And 8A, 8B, 9A, 9B, 10A, and 10B are regularly arranged by repeating the pitch variations, but the dimensions and arrangement of these block land portions can be appropriately changed according to the conditions.

Two block land portions 8A having different block widths and adjacent to each other with the lateral groove 6a or 6b or 6c interposed therebetween.
And 8B, 9A and 9B, 10A and 10B, the narrow block land portion 8B or 9B or 10B has four sides a, b, c of the block land portion as compared with the wide block land portion 8A or 9A or 10A, respectively. , D, at least one side surface is arranged at a large angle with respect to the block land surface 13.

Further, in FIG. 1, in order to make the rigidity in the block land portion more uniform, the one-sided opening lateral sipe 7 extending along the block width direction from the circumferential groove 3 and terminating in the land portion is connected to the narrow block land portion 8B. Alternatively, the sipe length of the wide block land portion 8A or 9A or 10A is arranged to be longer than that of 9B or 10B, but the one end opening lateral sipe 7 can be provided as necessary. Length, sipe depth,
It is also possible to change the sipe width and the like according to the rigidity of the land portion.

The circumferential groove 3 may be bent at a predetermined pitch shorter than the tire ground contact length, and may have groove wall portions protruding alternately inward and outward in the tread width direction. Within this range, the arrangement shape may be changed. You can Further, the number of the peripheral grooves 3 is preferably about 2 to 4, and from the viewpoint of drainage, the peripheral grooves are preferably see-through.

The block land portion located between the two circumferential grooves 3 is provided with two sub circumferential grooves 14 for dividing the block width into three for ensuring drainage. It is not an indispensable constituent element of the invention and can be appropriately arranged.

[0012]

The pneumatic tire of the present invention has two block land portions which are adjacent to each other across the lateral groove and have different block widths. The narrow block land portion is 4 times larger than the wide block land portion. By arranging at least one of the side surfaces at a large angle with respect to the surface of the block land portion, the rigidity of the narrow block land portion can be increased wholly or partly, whereby the narrow block land portion is formed. The rigidity of the portion and the rigidity of the wide block land portion can be made uniform. Further, by arranging the side surface of the block land portion having a low rigidity at a larger angle with respect to the surface of the block land portion, the rigidity in the block land portion can be made uniform.

Further, by disposing the one-sided opening lateral sipe in the block land part and increasing the one-sided opening lateral sipe in the wide block land part in comparison with the narrow block land part, the sipe volume is increased. It has an effect of promoting uniformization of rigidity between the parts and the land part of the block.

[0014]

EXAMPLE A specific example of the pneumatic tire according to the present invention will be described with reference to FIG. Example The invention tire having the tread pattern 1 shown in FIG.
The size is P195 / 65R15, and the tread portion 1 is bent at a predetermined pitch shorter than the tire contact length,
By dividing by two see-through circumferential grooves 3 having groove wall portions 4 that alternately project inward and outward in the tread width direction 2 and a plurality of lateral grooves 6 that extend across the bent portions 5 of the circumferential groove 3, Block land groups 11, 12 on both shoulder sides
Of the three types of wide block land portions 8A, 9A and 10A having the same block width (46.2 mm) and the pitch ratios of 8.5, 10.0 and 11.5, and the block width (4
4.7 mm) and the pitch ratio is 8.5, 10.0, 1
3 types of narrow block land parts 8B, 9B, 1
0B and 0B are regularly arranged by repeating pitch variations of 8A, 8B, 9A, 9B, 10A, and 10B. Two block land portions 8A and 8 having different block widths that are adjacent to each other with the lateral groove 6a or 6b or 6c interposed therebetween.
B, 9A and 9B, 10A and 10B, three side surfaces a of the four side surfaces a, b, c and d of the block land portion,
b and c are arranged at an angle shown in Table 1 with respect to the block land surface 13. The angle of the remaining side surface d of the block land portion was 90 ° in all the block land portions. FIG. 3 shows a groove cross section when the pattern shown in FIG. 1 is cut along the XX plane, the YY plane, and the ZZ plane. 8, 9, 10 and R means the alphabet of either A or B), and the angle between the side a and the block land surface 13 is θanR, and the side b and the block land. The angle formed by the part surface 13 is represented by θbnR, and the angle formed by the side surface c and the block land surface 13 is represented by θcnR. In addition, each block land portion is provided with a one-end opening lateral sipe 7 extending from the circumferential groove 3 along the block width direction and terminating in the land portion. The one-end opening lateral sipe 7 has a widened end portion in the land portion, and particularly, including this widened portion, the block land portion 8A,
In 9A and 10A, the block width was 0.9 times, and in the block land portions 8B, 9B and 10B, the length was 0.8 times, and the sipe depth was constant. Further, between the two circumferential grooves 3, two sawtooth-shaped auxiliary circumferential grooves 14 that further divide the block width of the block land portion into three are arranged. The carcass consisted of two plies with polyester cords arranged, and the belt consisted of two steel cord rubberized layers and one nylon cord rubberized layer.

[0015]

[Table 1]

Conventional Example In the conventional tire used in the conventional example, the angles formed by the four side surfaces of each block land portion and the block land portion surface are all 90 °,
It has substantially the same structure as the tire used in Example 1 except that the sipe length of the one-end opening lateral sipe 7 is the same (0.8 times the block width) in all the block land portions.

Test method In the test, after running for 10,000 km with an indoor drum tester having a safety walk on the drum, in the block land portion 9A of the block land portion group 11 on the shoulder side, uneven wear is generally caused. A step due to the difference in the amount of wear at the positions of the step-in side portion 15 and the kick-out side portion 16 shown in FIG. Table 2 shows the test results. The numerical values in the table are shown as an index ratio with the conventional example being 100 when the step is measured, and the larger the value, the better.

[0018]

[Table 2]

From Table 2, in the example, uneven wear was suppressed as compared with the conventional example. We also measured the passing noise,
No significant difference was observed between the example and the conventional example.

[0020]

According to the present invention, by arranging the four side surfaces of the block land portion at the proper angle for each block land portion, two block land portions adjacent to each other across the lateral groove and having different block widths are provided. Rigidity between the parts and in the land part of the block can be made uniform, and thus uneven wear is suppressed. Also, the same effect can be obtained by disposing a predetermined one-end opening lateral sipe on the block land portion.

[Brief description of drawings]

FIG. 1 is a diagram showing a part of a typical tread pattern of a pneumatic tire according to the present invention.

FIG. 2 is an enlarged view of the tire shown in FIG. 1 in which two block land portions adjacent to each other across a lateral groove and having different block widths are extracted.

FIG. 3 is a side surface a of a block land portion with respect to a block surface;
It is sectional drawing for showing the angle which b and c make.

[Explanation of symbols]

 1 tread portion 2 tread width direction 3 circumferential groove 4 circumferential groove groove wall portion 5 circumferential groove bent portion 6, 6a, 6b, 6c lateral groove 7 one end opening lateral sipes 8A, 9A, 10A narrow block land portion 8B, 9B, 10B Wide block land part 11, 12 Shoulder side block land part group 13 Block land part surface 14 Sub circumferential groove 15 Block landing side part 16 Block landing side part

Claims (2)

[Claims] 1. A plurality of circumferential grooves that are bent in a tread portion at a predetermined pitch shorter than a tire ground contact length and have groove wall portions that alternately project inward and outward in the tread width direction, and a plurality of grooves that extend across the bent portions of the circumferential grooves. By dividing with the lateral groove of the book,
In a pneumatic tire formed by forming block land portions of different sizes, a block land portion with a short block width is a block with a long block width between two block land portions with different block widths that are adjacent to each other across the lateral groove. A pneumatic tire characterized in that at least one of the four side surfaces of the block land portion is arranged at a larger angle with respect to the surface of the block land portion than the land portion. 2. A one-sided open lateral sipe extending from the circumferential groove in the block width direction and terminating in the land portion is provided in the block land portion,
The pneumatic tire according to claim 1, wherein the sipe volume of the one-end opening lateral sipe of the block land portion having a long block width is made larger than that of the one-end opening lateral sipe of the block land portion having a short block width.