JPS62251206A - Radial tire - Google Patents

Abstract

PURPOSE:To reduce noise and prevent the lopsided wear of a tread part by forming plural sipes mutually in parallel on the block or rib of a tread pattern and gradually increasing the interval between said sipes of each block or rib toward a specified direction. CONSTITUTION:Plural main grooves 5 are annularly provided along the circumferential direction EE' of tire on a tire tread face, and plural sub-grooves 6 which extends in the width direction of tire are provided from the main grooves 5, forming ribs (m). In such a structure, plural sipes 4 are formed mutually in parallel in the width direction of tire at 80-90 deg. to the circumferential direction EE' of tire, on the block or rib (m). And, the intervals between the sipes 4 are gradually increased from each other as the blocks or ribs are shifted from the blocks or ribs 1 on the center part in the width direction of tire to the blocks or ribs 2, 3 toward the shoulder part. Thereby, noise can be reduced while the lopsided wear of the tread part can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a radial tire with reduced noise.

[Prior art]

Conventionally, in a tread pattern in which blocks or ribs are defined on the tire tread surface, sipes are provided in the blocks or ribs in order to achieve an appropriate ratio of rigidity of the blocks or ribs and to reduce noise. Since the way the sipes are inserted has a large effect on tire performance, various improvements have been made in the way the sipes are inserted.

An example of how to insert sipes is shown in Figure 3. FIG. 3 is an explanatory diagram showing an example of a tread pattern of a conventional radial tire. In Figure 3, the tire tread surface has a tire circumferential direction E.
A plurality of main grooves 5 are annularly provided in E', and a plurality of sub-grooves 6 are arranged extending from these main grooves 5 in the tire width direction, and blocks or ribs m are defined by these grooves. There is. 1 represents a block or rib at the center in the width direction of the tire, 2 represents a partial block or rib at the shoulder near the center, 3 represents a partial block or rib at the shoulder, and 4 represents a block or rib m in the tire width direction. It is a formed sipe. The distance a+ between the sipes in the center block or rib l (hereinafter referred to as sipe pitch) is equal to the sipe pitch a2 in the shoulder partial block or rib 2 near the center and the sipe pitch a3 in the shoulder partial block or rib 3 (
'a+=32=23). Note that T is the tire ground contact width.

[Purpose of the invention]

An object of the present invention is to provide a radial tire that reduces noise, prevents uneven wear of the tread (step wear, shoulder wear), increases running life, and improves running stability on wet roads. shall be.

[Structure of the invention]

For this reason, the present invention provides a tread pattern in which a plurality of grooves are provided on the tire tread surface and blocks or ribs are partitioned by these grooves, and the blocks or ribs are provided with grooves in the tire width direction at an angle of 80° to 90° with respect to the tire circumferential direction. Summary of a radial tire characterized in that a plurality of sipes are formed parallel to each other, and the spacing between the sipes is gradually increased as it moves from a block or rib at the center part in the tire width direction to a block or rib at the shoulder part. That is.

Hereinafter, the configuration of the present invention will be explained in detail with reference to the drawings. Note that the same parts as in FIG. 3 are represented by the same numbers.

FIG. 1 is an explanatory diagram showing an example of a tread pattern of a radial tire of the present invention. In Fig. 1, the block or rib m has an angle of 80° to the tire circumferential direction EE'.
A plurality of sipes 4 are formed parallel to each other in the tire width direction at an angle of 90°.

The direction of Sipe 4 is 80° to the tire circumferential direction EIE'
If there are no drops, running stability will be reduced when running on a wet road, and if the sipes 4 are not formed parallel to each other, excess movement will occur on the block or rib surface that is subdivided by multiple sipes. However, this is undesirable since there is a risk of inducing local step wear and cracking from the rubber at the end of the sipe.

In addition, in the present invention, from the block or rib at the center part in the tire width direction (block or rib 1 at the center part in the tire width direction) to the block or rib at part of the shoulder (partial block or rib 2 at the shoulder part near the center part) The distance between the sipes is gradually increased as it moves to some blocks or ribs 3).

In other words, the sipe pitch is changed from dense to sparse (
a3>32>at)* By changing the sipe pitch in this way, the stiffness of the rubber in each part separated by each sipe changes, dispersing the peak of stiffness change due to tire rotation, and reducing noise. This is possible.

The sipe pitch t may be 3 to 10 m5+, or t-
/1m+n (a3/at in Figure 1) is 1.2<L m
af/jyu. Preferably <1.9, t is 3
If it is less than mm, the rigidity of the blocks or ribs m in the block or rib 1, the shoulder partial block or rib 2 near the center portion, and the shoulder partial block or rib 3 will be insufficient, which is not preferable because the steering stability will deteriorate. Furthermore, if t exceeds 10 mm, the effect of arranging the sipes will not be sufficiently exhibited.* L M-'/ L at
. When L is smaller than 1.2, the effect of the present invention cannot be fully exhibited; on the other hand, when L −x / L 11111 is 1
．． If it exceeds 9, t1lln becomes too small or t,
, becomes too large and the effect weakens.

Thickness and width of sipe) S is 0.6s+s ~ 1.2mm
It is preferable that

The distance e between the end of the sipe and the main groove is 211111~6-
- is preferred. If it is less than 2III11, abnormal wear will occur between the end of the sipe and the main groove, which is undesirable, but if it exceeds 6+a@, the effect of subdivision due to the arrangement of the sipe, that is, step wear, This is because the effect of improving shoulder wear is not sufficiently exhibited.

Regarding the depth d of the sipe, it is preferable that the ratio d/D is within the range of 0.3 to 1.0, where D is the depth of the main groove. If d/D is less than 0.3, the effect of subdivision by arranging the sipes, that is, the effect of improving step wear and shoulder wear, will not be sufficiently exhibited, and if d/D is less than 1.
．． This is because if it exceeds 0, the rigidity of the block or rib m in the shoulder partial block or rib 2 and the shoulder partial block or rib 3 near the center of the block or lip 11 is undesirably reduced.

If d is set so that d/D is in the range of 0.3 to 1.0, it will contribute to improving drainage performance and can also significantly improve wet road running performance.

Although the shape of the sipe is a straight sipe in FIG. 1, the object of the present invention can also be achieved by using a sipe with a curvature as an applied example.

゛ Examples are shown below.

Example The sound pressure level (dB) of the following tires of the present invention and conventional tires was evaluated. The results are shown in FIG.

Note that the sound pressure level was evaluated using the following method.

(1) Tire of the present invention.

Tire size 185/7011R13゜Load 450k
g.

APl, 9kg/c+a, U 5-J x 13°-'l-eve dimensions; S=0.6mm Se=3~3
．． 5+++m Sd /D = 0.36 to 0°84° The sipe direction is 90° to the tire circumferential direction.

The sipe shape is straight. a3=7mm, a2=611III
I, al = 5mm (a3 > a2 > aI) m
t-, M/Ls+.

-1,4.

(2) Conventional tires.

Tire size 185/7011R13, load 450k
g.

APl, 9 kg/li. Rim 5-J X13. Sipe dimension; S-0.6+ms S e =3 ~ 3.5
ms, d/D = 0.36~0°84, sipe direction is 90'' with respect to the tire circumferential direction.

Sipe shape is straight *a3=6sn, a2=6mmsa1
=6ms (a3=82=at).

Standing level -°: The evaluation method is based on the stand-alone bench test method of "Tire Noise Test Method" of JASOC606-".

In FIG. 2, l represents the tire of the present invention and n represents the conventional tire. As can be seen from FIG. 2, the tire of the present invention has a lower sound pressure level and reduced noise than the conventional tire.

〔Effect of the invention〕

As explained above, according to the present invention, the blocks or ribs of the tread pattern have an angle of 80° to 90° with respect to the tire circumferential direction.
By forming a plurality of sipes parallel to each other in the width direction of the tire, the distance between the sipes gradually increases as the block or rib in the center part of the tire widthwise moves to the block or rib in the shoulder part. Furthermore, uneven wear of the tread portion can be prevented, the running life can be increased, and running stability on wet roads can be improved.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an example of the tread pattern of the radial tire of the present invention, Fig. 2 is a diagram showing the relationship between sound pressure level and running speed, and Fig. 3 is an explanatory diagram showing an example of the tread pattern of a conventional radial tire. It is a diagram. 1... Block or halip at the center part in the tire width direction,
2...Part of the shoulder block or rib near the center part, 3...Part of the shoulder block or rib, 4...
Sipe, 5...Main groove, 6...Sub groove, m...Block or rib.

Claims (1)

[Claims] In a tread pattern in which a plurality of grooves are provided on the tire tread and blocks or ribs are defined by these grooves, the blocks or ribs have an angle of 80° to 90° with respect to the tire circumferential direction.
to form multiple sipes parallel to each other in the tire width direction,
A radial tire characterized in that the spacing between the sipes gradually increases as it moves from the block or rib at the center part in the width direction of the tire to the block or rib at the shoulder part.