JPH06239105A - Pneumatic radial tire for heavy load - Google Patents

Abstract

PURPOSE:To suppress removal and damage while preventing a wandering and a deflecting abrasion. CONSTITUTION:While a tread 1 is divided into shoulder ribs 3 at the outermost sides and at least one line of center rib 4 positioning between them, by at least two lines of main grooves 2 extending almost in the circumferential direction of a tire T, small auxiliary grooves 5 extending almost parallel to the main grooves 2 are formed to the shoulder ribs 3, so as to compose this pneumatic radial tire for heavy load. The auxiliary groove 5 is formed extending in the circumferential direction in a zigzag form by continuing with an outer groove 5A, an inner groove 5B, and a communicating groove 5C, and the groove depth h1 of the outer groove 5A is formed smaller than the groove depth h2 of the inner groove 5B. The auxiliary groove 5 consists of the outer groove 5A and the inner groove 5B extending intermittently in the circumferential direction of the tire T, and the outer groove 5A and the inner groove 5B at the opposite side are formed overlapping in the circumferential direction to the intermittent parts in the circumferential direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy duty pneumatic radial tire used for trucks, buses and the like.

[0002]

2. Description of the Related Art Conventionally, as a tread pattern for a heavy-duty pneumatic radial tire that travels on a good road at a high speed, generally, a so-called rib type tread pattern, that is, a plurality of tread patterns each having 2 to 4 wide main grooves is generally used. However, one of the major drawbacks of this type of tire is the problem of wandering caused by the rigidity of the shoulder ribs.

As a measure against wandering, there is a method of increasing the radius of the shoulder edge, but in this case, shoulder drop wear occurs due to early wear of the entire shoulder rib. Conventionally, it was possible to deal with shoulder drop wear to some extent by increasing the radius of the crown in the tire or by increasing the width of the shoulder ribs.
There was an antinomy phenomenon that it had the opposite effect on wandering. In addition, shoulder wear is particularly severe in the tread half located outside the vehicle when the tire is used as a front wheel that is an idle wheel.Therefore, it may be prevented by rotating the tire. However, these days, tires with fixed shafts are often used, and the problem of uneven wear has become more apparent.

Further, as a countermeasure against shoulder drop wear of the shoulder ribs, a fine groove (sub-groove) extending in the circumferential direction is arranged near the edge of the shoulder rib. However, when tires are gathered on a green stone or the like, Damage occurs where the outside of the narrow groove is missing. That is, the closer the narrow groove is to the shoulder edge, the better for shoulder drop wear, but the more severe the missing damage is. There is a trade-off phenomenon of giving.

Therefore, as disclosed in Japanese Unexamined Patent Publication No. 61-143205, at least two wide main grooves extending substantially in the circumferential direction of the tire are used to attach the tread to both outermost shoulder ribs and the shoulder ribs. In the tire divided into at least one center rib located between the two, at least one shoulder rib has a width of 3% or less of the tread width and a depth of 30% or more of the depth of the adjacent main groove. A radial tire that is divided into at least two small ribs by at least one auxiliary groove extending substantially in the circumferential direction of the tire at a position where the distance between each of them and the tread end is less than 50% of the width of the shoulder rib. (Prior art tires).

[0006]

In the above-mentioned conventional tire, since the groove widths of the plurality of sub-grooves are all the same, the rigidity of the shoulder rib divided by the sub-grooves is inside and outside. It was almost the same, and it was difficult to prevent uneven wear while preventing wandering. Therefore, an object of the present invention is to disperse the stress concentrated in the sub-grooves by forming the shape of the sub-grooves formed in the shoulder ribs in a zigzag shape in the circumferential direction to prevent chipping and uneven wear.

Further, the auxiliary groove formed in the shoulder rib is formed as an inner / outer groove and is intermittently formed in the circumferential direction, so that the intermittent portion has a reinforcing function to prevent chipping and prevent uneven wear. The purpose is to

[0008]

SUMMARY OF THE INVENTION According to the present invention, at least two main grooves 2 extending in the circumferential direction of a tire T form a tread 1 on both outermost shoulder ribs 3 and at least one tread 1 located between them. In order to achieve the above-mentioned object, in a heavy-duty pneumatic radial tire in which the shoulder rib 3 is formed with a thin auxiliary groove 5 extending substantially parallel to the main groove 2, the following technical means are provided. Are taking.

That is, in the present invention according to claim 1, the sub-groove 5 is formed by continuously forming the outer groove 5A, the inner groove 5B and the connecting groove 5C and extending in a zigzag shape in the circumferential direction, and The groove depth h1 of the outer groove 5A is smaller than the groove depth h2 of the side groove 5B. Further, in the present invention according to claim 2, the sub-groove 5 includes an outer groove 5A and an inner groove 5B that are intermittently extended in the tire circumferential direction, and are opposed to the circumferential interrupted portions 5D and 5E. -The outer grooves 5A and 5B are formed so as to be wrapped in the circumferential direction.

[0010]

The various types of uneven wear generated on the shoulder ribs 3 are caused by local wear on the outer ends of the shoulder ribs 3 due to the lateral force generated during cornering and the differential drag during straight running. By the action of the lateral force and the differential drag, it progresses in the circumferential direction, the axial direction, and the depth direction, and the growth progresses from edge drop wear to various uneven wear.

In the present invention, the sub-groove 5 formed on the shoulder rib 3 has a zigzag shape in the circumferential direction in which the inner and outer grooves 5A and 5B are continuous with the connecting groove 5C, so that the stress acting on the sub-groove 5 is dispersed. In addition, the groove depth of the inner / outer grooves 5A, 5B is further prevented because the outer groove 5A is shallow and the inner groove 5B is deep. Further, in the present invention, the sub-groove 5 formed in the shoulder rib 3 is composed of inner and outer grooves 5A and 5B which are interrupted in the circumferential direction, and the interrupted portions 5D and 5
E serves as a reinforcing band to prevent chipping, and since the inner groove 5B is formed facing the interrupted portion 5D, shoulder drop wear (uneven wear) is also prevented.

[0012]

FIG. 1 shows an embodiment of the present invention according to claim 1.
FIG. 1 shows an embodiment of the present invention according to (A) and claim 2.
In (B), the tread 1 is at least two linearly extending along the circumferential direction of the tire T, and is 4 in this embodiment.
The wide main groove 2 of the book divides into two shoulder ribs 3 located on both outermost sides of the tread 1 and at least one shoulder rib 3 located in a more central portion of the tread 1 in this embodiment, three center ribs 4. Has been done.

The main groove 2 is so wide that the groove walls do not come into contact with each other in the ground contact area when the tire rolls under load. The left and right shoulder ribs 3 each have a thin sub-groove 5 extending substantially parallel to the main groove 2 in FIG. 1A, and the sub-groove 5 connects the outer groove 5A and the inner groove 5B with a connecting groove 5C. The grooves 5 are continuously formed in a zigzag shape, and the groove depth h1 of the outer groove 5A is smaller (shallow) than the groove depth h2 of the inner groove 5B.

As shown in FIGS. 2A and 2B, the sub groove depth h
1 and h2 are both set to 60 to 120% of the depth H of the main groove 2, and the groove width of the sub groove 5 is 2.5 mm to 0.
It is set to 5 mm. Here, the groove width is 0.5 to 2.5 m
The reason why m is set is that if it is less than 0.5 mm, it is meaningless to form a groove, and if it is 2.5 mm or more, step wear occurs.

Further, the groove length of the auxiliary groove 5 is determined by the outer groove 5
If the length of A is C1 and the length of the inner groove 5B is C2, then C1 ≦ C2. In FIG. 1 (B),
The sub groove 5 is an inner / outer groove 5 that extends intermittently in the tire circumferential direction.
A and 5B are formed, and the interrupted portions 5D and 5E in the circumferential direction serve as reinforcing bands, respectively, and the inner and outer grooves 5A and 5B facing each other are wrapped in the circumferential direction.

In the tire according to claim 2 shown in FIG. 1 (B), the groove depths h1 and h2 and the groove width may be set to be the same as those in the above-mentioned embodiment according to claim 1. Even if the groove depths h1 and h2 are the same, it is desirable that the outer groove 5A is wide and the inner groove 5B is narrow with respect to the groove width. However, it is free to widen the inner groove 5B and narrow the outer groove 5A.

Regarding the groove length as shown in FIG. 3, it is desirable that the length C1 of the outer groove 5A be longer than the length C2 of the inner groove 5B, but as shown in FIG.
1, C2 may have the same length, and although not shown, the length C1 of the outer groove 5A may be different from each other. In this respect, the same applies to the inner groove 5B. is there.

Further, as shown in FIG. 4, in the embodiment of the present invention according to claim 1, two or two zigzag-shaped auxiliary grooves 5 are provided.
It is also possible to form more than one book.

[0019]

As described above in detail, in the present invention according to claim 1, the sub-groove 5 formed in the shoulder rib 3 is continuously formed by the outer groove 5A, the inner groove 5B and the connecting groove 5C in the circumferential direction. Since the tire T is stretched in a zigzag shape, when the tire T rides on green stone, stone, etc., the stress concentrated in the sub-groove 5 is dispersed, so that the outside of the sub-groove 5 can be prevented from being chipped.

Further, since the groove depth h1 of the outer groove 5A is smaller than the groove depth h2 of the inner groove 5B, the outer groove 5A is reinforced so that the chipping is further prevented.
Further, in the present invention according to claim 2, the auxiliary groove 5 formed in the shoulder rib 3 is composed of an outer groove 5A and an inner groove 5B which are intermittently extended in the tire circumferential direction, and the circumferential interrupted portion 5 is formed.
Since the inner and outer grooves 5A and 5B facing each other are formed in the D and 5E so as to overlap each other in the circumferential direction, the interrupted portions 5D and 5E serve as a reinforcing band to prevent chipping.

Therefore, in the present invention, uneven wear on the inner side can be reduced while preventing wandering.

[Brief description of drawings]

1 is an embodiment of the present invention according to claims 1 and 2, wherein (A) is a perspective view according to claim 1, and (B) is claim 2;
It is a perspective view which concerns on.

FIG. 2 shows a main part according to claim 1, (A) is a plan view,
(B) is a sectional view.

FIG. 3 is a plan view of a main part according to claim 2.

FIG. 4 is a second embodiment according to claim 1, (A) is a plan view, and (B) is a sectional view.

5 is a plan view of a second embodiment according to claim 2. FIG.

[Explanation of symbols]

 T Tire 1 Tread 2 Main groove 3 Shoulder rib 5 Sub groove 5A Outer groove 5B Inner groove 5C Connecting groove 5D Interrupted portion 5E Interrupted portion

Claims (2)

[Claims] 1. A tread (1) having at least two main grooves (2) extending in a substantially circumferential direction of a tire (T) and at least one tread (3) located between the outermost shoulder ribs (3) and between them. In the radial radial tire for heavy load, the shoulder rib (3) is formed with a thin sub-groove (5) extending substantially parallel to the main groove (2) in the shoulder rib (3). ) Is formed by continuously extending the outer groove (5A), the inner groove (5B) and the connecting groove (5C) and extending in a zigzag shape in the circumferential direction, and the groove depth (h2) of the inner groove (5B).
The pneumatic radial tire for heavy loads is characterized in that the groove depth (h1) of the outer groove (5A) is smaller than that of the outer radial groove (5A). 2. A tread (1) is located on both outermost shoulder ribs (3) and at least one between them, by means of at least two main grooves (2) extending substantially in the circumferential direction of the tire (T). In the radial radial tire for heavy load, the shoulder rib (3) is formed with a thin sub-groove (5) extending substantially parallel to the main groove (2) in the shoulder rib (3). ) Is composed of an outer groove (5A) and an inner groove (5B) that are intermittently extended in the tire circumferential direction, and inner and outer grooves (5A) that face the circumferentially interrupted portions (5D) (5E).
(5B) is formed by lapping in the circumferential direction, and a heavy-duty pneumatic radial tire is provided.