JP3365690B2 - Pneumatic radial tire - Google Patents

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 is mainly used for trucks and buses.

[0002]

2. Description of the Related Art FIG. 5 is a development view of a tread portion 1 of a conventional pneumatic radial tire T used for trucks and buses. In FIG. 5, a center rib 2 extending linearly in the circumferential direction is provided at the center of the tread portion 1, and center main grooves 3 and 4 are provided on both left and right sides of the center rib 2.
Side ribs 5 and 6 extending linearly in the circumferential direction through
Shoulder ribs 9 and 1 extending in the circumferential direction on the left and right outer sides of the side ribs 5 and 6 via side main grooves 7 and 8.
No. 0, one of the side ribs 5 and 6, that is, the side rib 5 on the right side in the figure, is formed with first narrow shallow grooves 11 that extend in the circumferential direction and extend in the circumferential direction at intervals in the circumferential direction. On the other hand, on the other side 6, the second thin shallow grooves 12 which cross the rib longitudinal direction and have a tapered shape in the circumferential direction are formed at intervals in the circumferential direction so that the wet performance and the ribs 2, 5, 6 are formed. , 9 and 10 are improved in trackability to the ground plane.

[0003]

In the prior art shown in FIG. 5, the first and second thin shallow grooves 11 and 12 have a substantially triangular two-sided shape, and the side ribs 5 are divided by the circumferential direction. 6
Is in the form of an arrow blade. Therefore, when the tire T is mounted on a truck, a bus, or the like, the top 5
In parts A and 6A, uneven wear such as heel and toe and rib punch was likely to occur.

Therefore, in the present invention, by devising the form of the first and second thin shallow grooves, the grip performance at the time of initial wear is ensured, and the heel and toe, rib punch and the like are biased while securing wet grip performance. The purpose is to reduce wear.

[0005]

The present invention provides a tread portion 2
Center rib 2 extending in a straight line in the circumferential direction at the center of 0
4 and side ribs 27, 28 extending in a straight line in the circumferential direction via center main grooves 25, 26 on both left and right sides of the center rib 24, and side main grooves 29 on the left and right outer sides of the side ribs 27, 28. The side ribs 2 are provided with shoulder ribs 31 and 32 extending in the circumferential direction through 30.
First thin shallow grooves 33 are formed on one side of the ribs 7 so as to cross the rib longitudinal direction and spread in the circumferential direction at intervals in the circumferential direction, and on the other side rib 28, the rib longitudinal direction is formed. In the pneumatic radial tire T in which the second narrow shallow grooves 34 which are transverse and are tapered in the circumferential direction are formed at intervals in the circumferential direction, in order to achieve the above-mentioned object,
The following technical measures are taken.

That is, according to the present invention, the first and second shallow grooves 33, 34 are formed in an arc shape having a radius centered within the rib width displaced to the center line side from the rib centers of the side ribs 27, 28. In addition, the groove depth is shallower than the groove depths of the main grooves 25 and 26.
The left and right shoulder ribs 2 of the center rib 24 and the left and right shoulder ribs 2 on the arc-shaped extensions of the first and second shallow grooves 33, 34.
Cutouts 35 and 36 are formed on the inner edges of the cutouts 7 and 28, and the cutouts 35 and 36 are preferably out of phase with each other in the circumferential direction.

Further, the notch 3 of the center rib 24
Inner edge between 5 and the first of the left and right side ribs 27, 28
It is desirable to form a stress distribution cut 37 on the left and right inner edges between the two narrow shallow grooves 33 and 34 and on the inner edges between the notches 36 of the left and right shoulder ribs 31 and 32. Further, it is desirable that the radii of the first and second thin shallow grooves 33 and 34 and the notches 35 and 36 be 80 to 105% of the rib width of the side ribs 27 and 28.

[0008]

When the pneumatic radial tire T according to the present invention is mounted on a truck, a bus, or the like to run, the center rib 2
4, straightness is ensured by the left and right side ribs 27, 28 and the left and right shoulder ribs 31, 32, and the left and right center main grooves 25, 26 and the side main grooves 29, 30 are secured.
To ensure drainage.

When the left and right side ribs 27, 28 are in contact with the road surface, the first and second shallow grooves 33, 34 formed across the ribs 27, 28 ensure grip performance during initial wear. Since the first and second thin shallow grooves 33, 34 are arcuate in shape, the stress at their edge portions gradually acts so that the stress is not concentrated and uneven wear such as heel and toe and rib punch is surely prevented. Not only does the drainage become better than the arrow blade form (conventional example), but noise is not increased.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. Pneumatic radial tire (10
00R20-14PR) T has the form shown in FIGS. 2 and 3, and has a bead portion 23 fitted to the rim from the tread portion 20 via the left and right shoulder portions 21 and side wall portions 22 as shown in FIG. It has a toroidal cross section.

As shown in FIGS. 1 to 3, a center rib 24 extending linearly in the circumferential direction is provided at the center of the tread portion 20, and the center main groove 2 is provided on the left and right of the center rib 24.
5 and 26 have side ribs 27 and 28 extending linearly in the circumferential direction through the side ribs 27 and 2.
Shoulder ribs 31 and 32 are provided on the left and right outer sides of 8 via side main grooves 29 and 30, respectively.

On one of the side ribs 27 and 28, there is formed a first rib which extends across the longitudinal direction of the rib and widens in the circumferential direction.
The thin shallow grooves 33 are formed at intervals in the circumferential direction, and on the other side ribs 27 and 28, there is formed in the circumferential direction a second thin shallow groove 34 that traverses the longitudinal direction of the rib and is tapered in the circumferential direction. They are formed at intervals. The first and second thin shallow grooves 3
As shown in FIG. 1 (C), the grooves 3 and 34 have groove depths of 1 and 5 m.
The groove width is about 2 mm at about m, and as shown in FIG. 1 (A), it has an arc shape with a radius R having a center O within the rib width displaced from the center of the rib toward the center line side.

The radius R is 80 to 10 with respect to the rib width.
5% and the deviation amount of the center O is 7 to the rib width.
It is 9%. Here, if the radius R is less than 80% of the rib width, the thin shallow grooves 33, 34 stand up too much and uneven wear is likely to occur. On the other hand, if it is 105% or more, a linear shape (too much sleep in the width direction) is obtained. Therefore, the radius R
Is 80 to 105%.

Next, an example of radius R is 1000R
In the radial tire T of 20, the tread width 184
In mm, R was set to 87.7%. Further, in the radial tire T of 750R20, the tread width of 142 mm is 9
It was set to 5.2%. In this way, the radius suitable for the tire shape according to various required performances such as increasing the tread width to improve wear resistance performance, changing the number of pitches to suppress noise, increasing the tire outer diameter, etc. The ratio of R can be selected.

Notches 35, 3 are formed on the inner edges of the left and right shoulder ribs 31, 32 of the center rib 24 on the arc-shaped extensions of the first and second thin shallow grooves 33, 34.
6 are formed, and the notches 35 and 36 are circumferentially out of phase with each other, thereby suppressing noise while ensuring drainage. As shown in FIG. 1 (A), the notches 35, 36 have expanded portions 35A, 36A, and the groove depths of the expanded portions 35A, 36A are shown in FIG. 1 (B). It is slightly shallower than the depth of the main groove.

Furthermore, the inner edge between the notches 35 formed on both edges of the center rib 24, the left and right inner edges between the first and second shallow grooves 33, 34 of the left and right side ribs 27, 28, and the left and right shoulder ribs. At the inner edge between the notches 36 in 31, 32, a stress distribution cut 37 is formed, and the depth of the cut 37 is, for example, about 11.5 mm.

[0017]

According to the present invention described in detail above, by forming the first and second thin shallow grooves in the left and right side ribs across the longitudinal direction, the heel and toe and the rib punch can be secured while ensuring the initial grip. Uneven wear can be prevented, and since the first and second shallow grooves are formed in an arc shape, the edge part has little jumping (movement) and stress concentration is alleviated, so uneven wear can be reliably prevented. However, compared to the conventional arrow-blade-shaped narrow groove, it is possible to improve drainage and ensure wet grip performance, and also suppress noise generation.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, (A) is a development plan view,
FIG. 1B is an enlarged sectional view of a B portion in FIG. 1A, and FIG. 1C is an enlarged sectional view of a C portion.

FIG. 2 is a front view of a tire according to an embodiment of the present invention.

FIG. 3 is a perspective view of a tire according to an embodiment of the present invention.

4 is a cross-sectional view taken along the line AA of FIG.

FIG. 5 is a developed plan view of a conventional example.

[Explanation of symbols]

T tire 20 tread section 24 Center rib 25, 26 Center main groove 27, 28 Side ribs 29, 30 Side main groove 31, 32 Shoulder rib 33 First shallow groove 34 Second shallow groove 35, 36 Notch

Claims (4)

(57) [Claims] 1. A center rib (24) extending linearly in the circumferential direction is provided at the center of the tread portion (20), and center main grooves (25) are provided on both left and right sides of the center rib (24).
The side ribs (27) and (28) extending in a straight line shape in the circumferential direction via the (26) are provided, and the side ribs (27) and (2) are provided.
8) Shoulder ribs (31) (32) extending in the circumferential direction through side main grooves (29) (30) are provided on the left and right outer sides of 8), and one of the side ribs (27) crosses the rib longitudinal direction. In addition, the first narrow shallow groove (3
3) are formed at intervals in the circumferential direction, and on the other side rib (28), a second thin shallow groove (34) is formed in the circumferential direction that crosses the longitudinal direction of the rib and tapers in the circumferential direction. In the pneumatic radial tire (T) formed at intervals, the first and second thin shallow grooves (33) (34) are displaced toward the center line side from the rib centers of the side ribs (27) (28). Also, the pneumatic radial tire is characterized in that it has an arcuate shape having a radius centered within the rib width and has a groove depth shallower than the groove depth of the main grooves (25) (26). 2. A notch on the inner edge of the left and right shoulder ribs (27) (28) of the center rib (24) on the arc-shaped extension of the first and second shallow grooves (33) (34). The pneumatic radial tire according to claim 1, wherein (35) and (36) are formed, and the notches (35) and (36) are out of phase with each other in the circumferential direction. 3. The notch (3) of the center rib (24).
5) Inner edge, left and right side ribs (27) (2)
8) The first and second narrow shallow grooves (33) (34) between the left and right inner edges and the left and right shoulder ribs (31) (32) at the inner edge between the notches (36), the stress distribution cuts (3).
7) is formed, The pneumatic radial tire according to claim 2. 4. The radius of the first and second narrow shallow grooves (33) (34) and the notches (35) (36) is the side rib (27).
The pneumatic radial tire according to any one of claims 1 to 3, wherein the rib width in (28) is 80 to 105%.