JPH05338413A - Radial tire for heavy load - Google Patents

Abstract

PURPOSE:To make it hard for a stone to get into a groove part and to make it easy to release the stone having got into the groove part by forming at least two step parts in the groove part and varying width and height of the step parts. CONSTITUTION:A groove part 2 having step differences of at least two step parts in the tire circumferential direction is formed. When width of the groove 2 is defined as Gw, width Gw of a first step part 3 of the groove 2 and wide Gw of a second step part 4 are specified as 0.1Gw<Gw1<0.30Gw, 0.1Gw< Gw2<0.30Gw. Additionally, when depth of the groove part 2 is defined as H, height H1 from the groove part bottom surface of the first step part 3 and height H2 from a groove part bottom surfaces 5 of the second step part 4 are specified as H1<=0.5H, H2<=0.5H1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy duty radial tire in which stones are unlikely to enter the grooves on the tire surface.

[0002]

2. Description of the Related Art Conventionally, in a heavy duty radial tire, when a vehicle equipped with the radial tire travels,
It is known that the tire groove portion 20 formed on the tire surface has different sectional shapes when unloaded (see FIG. 4) and when loaded (see FIG. 5).

[0003]

Generally, stone chips are generated at the ground contact portion of the tire while the tire rotates, and the width Gwg of the groove portion in FIG. 4 is the width of the groove portion at the non-ground portion. It is narrower than Gwn. In this way, when the shape of the groove portion 20 is different between when the stone is loaded and when the stone is not loaded, when a stone on the road surface enters the groove portion 20, the shape of the groove portion facilitates the stone to enter the groove portion 20 and the inside of the groove portion 20. The easiness of releasing the stone that has entered will be different. That is, as shown in FIG. 5, if the groove shape becomes a bag shape when loaded, there is a problem that it becomes difficult for stones to slip out when entering the groove portion. Further, the stone once entering the groove 20 will start to erode the rubber portion on the bottom of the groove 20 after reaching the bottom of the groove 20 due to repeated wear and load due to tire rotation, and eventually damage the belt. .. If the belt is damaged in this way, it will not be possible to rehabilitate the tire simply by renewing the tread rubber when renewing the tread rubber attached to the belt surface, and the life of the tire will be greatly reduced. It becomes a problem.

[0004] Generally, since stone engraving occurs when a stone having a diameter slightly larger than the width Gw of the groove enters the groove, if the width Gw of the groove> height H, the stone entangling does not occur. .. Therefore, in order to prevent the stone biting more reliably, one step portion is formed in the groove as shown in Japanese Patent Laid-Open No. 61-166708, and even if the stone biting occurs, it is more than necessary. There is a stone that prevents the stone from reaching the bottom of the groove.

However, in such a structure, since there is only one stepped portion, the width G of the groove portion is caused by the wear of the tire.
In some cases, w> height H may not be achieved, and stone entrapment may not be reliably prevented. Therefore, an object of the present invention is to solve the above problem, even if the tire is worn, it is difficult for stones to enter the groove portion, while the stones entering the groove portion are easily released from the groove portion and reach the groove bottom surface. It is to provide a heavy duty radial tire that is difficult to perform.

[0006]

In order to achieve the above object, the present invention has at least two step portions in a groove portion,
In addition, the width and height of the stepped portions are different from each other, and the groove width Gw> height H can be more reliably achieved even if the tire is worn. That is, a groove having at least two steps in the tire circumferential direction is provided, and the width of the groove is G.
When the width is w, the width Gw ₁ of the first step portion and the width Gw ₂ of the second step portion of the groove portion are 0.1 Gw <Gw ₁ <0.30 Gw,
0.1 Gw <Gw ₂ <0.30 Gw, and when the depth of the groove portion is H, the height H ₁ from the groove bottom surface of the first step portion and the height from the groove bottom surface of the second step portion. The height H ₂ is set such that H ₁ ≦ 0.5H and H ₂ ≦ 0.5H ₁ . In the above configuration, in the tire radial direction cross-sectional shape of the groove, the first wall is formed on the wall surface of the groove facing each other.
It is also possible to have a step portion and the second step portion, and the first step portions and the second step portions may have different depths.

[0007]

According to the structure of the present invention, the groove portion having at least two steps in the tire circumferential direction is provided, and
With respect to the width Gw of the groove portion, the width Gw ₁ of the first step portion of the groove portion
And the width Gw ₂ of the second stage portion are 0.1 Gw <Gw ₁ <0.3
0 Gw, 0.1 Gw <Gw ₂ <0.30 Gw, and the depth of the groove portion is H relative to H, the height H ₁ from the groove bottom surface of the first step portion and the groove bottom surface of the second step portion. The height H ₂ of the groove is configured so that H ₁ ≦ 0.5H and H ₂ ≦ 0.5H ₁ so that even if the tire is worn, the width Gw of the groove> the height H is more reliably achieved. be able to.
Therefore, even if the tire wears, the width Gw> height H of the groove can be maintained, so that the stone is hard to enter the groove, while the stone entering the groove is easily released from the groove,
Moreover, even if stone biting occurs, it is possible to prevent stones from reaching the bottom of the groove more than necessary.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments according to the present invention will be described below with reference to FIGS.
Will be described in detail based on. As described above, since the stone biting occurs when a stone having a diameter slightly larger than the width Gw of the groove portion enters the groove portion, if the width Gw of the groove portion> the height H, the stone biting does not occur. In particular, if the width Gwg of the groove portion is approximately equal to the height H in the ground contact surface, stone entrapment does not occur. In consideration of this, in order to prevent stone biting more reliably,
Like the radial tire for heavy load according to the present embodiment as shown in FIG. 1, a step is formed in the groove so that even if a stone bite occurs, the stone does not reach the bottom of the groove more than necessary. ..

That is, as shown in FIG. 1, a groove portion 2 is provided on a surface of a tire 1 in a tire circumferential direction, and a first step portion is provided on the left side in FIG. 3 and a second step portion 4 lower than the first step portion 3 on the right side in FIG. In this tire 1, the width Gw ₁ of the first step portion 3 and the width Gw 2 of the second step portion 4 of the groove portion ₂ are 0.1 Gw <Gw ₁ <0 when the width of the groove portion 2 is Gw. .30 Gw, 0.1
Gw <Gw ₂ <0.30 Gw.

Here, 0.1 Gw <Gw ₁ is set so that if 0.1 Gw ≧ Gw ₁ , it is possible to prevent the stone from penetrating deeper to the bottom of the groove than the bite position when the stone is bite. Because there is no. Further, Gw ₁ <0.30 Gw means that if Gw ₁ ≧ 0.30 Gw, the height H ₁ will be described later.
This is because the possibility of Gw> H from the to the bottom of the groove is reduced, and the stone entrapment prevention performance of the bottom of the groove within the height H ₁ is reduced. Also, the reason why 0.1 Gw <Gw ₂ is
This is because if 0.1 Gw ≧ Gw _{2 is} satisfied, it is impossible to prevent the stone from penetrating deeper into the bottom of the groove when the stone is bite. Further, Gw ₂ <0.30 Gw means that if Gw ₂ ≧ 0.30 Gw, it is less likely that Gw> H from the height H ₂ to the bottom of the groove, which will be described later, within the height H ₂ . This is because the stone entrapment prevention performance at the bottom of the groove is deteriorated. Further, the height H ₂ from the groove bottom 5 of the height H ₁ and the second stage portion 4 from the groove bottom 5 of the first stage portion 3 when the depth of the groove 2 and H is, H ₁
≦ 0.5H and H ₂ ≦ 0.5H ₁ .

Here, H ₁ ≤0.5H means that if H
_{If 1} > 0.5H, the final problem due to stone biting is the erosion of the rubber part at the bottom of the groove due to the bitten stone after the middle stage of wear, preventing stone biting from the middle stage of wear to the latter stage. This is to realize the performance more efficiently. Also, H
_The reason why ₂ ≤ 0.5H ₁ is the same as the above. According to the above embodiment, the groove portion 2 having the two portions 2 and 3 having different heights and widths in the tire circumferential direction is provided, and the width Gw of the first step portion of the groove portion with respect to the width Gw of the groove portion 2. ₁ and 2
The width Gw _{2 of the} step portion is 0.1 Gw <Gw ₁ <0.30 G
w, 0.1 Gw <Gw ₂ <0.30 Gw,
With respect to the depth of the groove portion with respect to H, the height H ₁ from the groove bottom surface of the first step portion and the height H ₂ from the groove bottom surface of the second step portion are H ₁ ≦ 0.5H, H ₂ By configuring so that ≦ 0.5H ₁ , even if the tire is worn, the width Gw> height H of the groove can be more reliably achieved. Therefore, even if the tire is worn, the width Gw of the groove> the height H can be maintained, so that it is difficult for stones to enter the groove,
It is possible to prevent the stone that has entered the groove from being easily discharged from the groove and prevent the stone from reaching the bottom of the groove more than necessary even if stone biting occurs.

The present invention is not limited to the above embodiment, but can be implemented in various other modes. For example,
As shown in FIG. 2, the first step portion 3 and the second step portion 4 are not limited to those formed on both sides of the groove portion 2, and the first step portion 7 and the second step portion 8 are formed only on one side. May be formed. Further, as shown in FIG. 3 (A), the first step portion 10 is exactly the same on both sides on the opposite wall surfaces of the groove portion.
The second step portion 11 may be formed. Also, FIG.
As shown in (B), the step portion 12 and the second step portion 13 are formed on the left side of the groove portion, while the first portion is formed on the right side of the groove portion.
Only one step portion 14 may be formed at a position facing the middle of the step portion 12 and the second step portion 13. Also, FIG.
As shown in (C), the first step portion 15 is provided on the left side of the groove.
And the second step portion 16 are formed, the first step portion 17 is formed on the right side of the groove portion so as to be higher than the left side step portions.
And the second step portion 18 may be formed.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a groove portion of a heavy duty radial tire according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a groove portion of a heavy duty radial tire according to another embodiment of the present invention.

3A to 3C are enlarged cross-sectional views of a groove portion of a heavy duty radial tire according to various embodiments of the present invention.

FIG. 4 is an enlarged cross-sectional view of a groove portion of a conventional radial tire when no load is applied.

5 is an enlarged cross-sectional view of the groove of FIG. 4 when loaded.

[Explanation of symbols]

1 ... Tire, 2, 6 ... Groove part, 3, 7, 10, 12, 1
5, 17 ... First stage part, 4, 8, 11, 13, 16, 1
8 ... 2nd step part, 5, 9 ... groove part bottom face, 14 ... step part.

Claims (2)

[Claims] 1. A groove portion (2, 6) having at least two steps in the tire circumferential direction, the width of the groove portion being Gw.
And the first step portion (3,7,10,1) of the groove
2,15,17) width Gw ₁ and the second step (4,8,1)
1, 13, 16, 18) has a width Gw ₂ of 0.1 Gw <G
w ₁ <0.30 Gw, 0.1 Gw <Gw ₂ <0.30 Gw, and when the depth of the groove is H, the first
The height H ₁ of the stepped portion from the groove bottom surface and the height H ₂ of the second stepped portion from the groove bottom surface are H ₁ ≦ 0.5H and H ₂ ≦ 0.5.
A heavy-duty radial tire characterized by being set to H ₁ . 2. The tire radial cross-sectional shape of the groove has the first step portion and the second step portion on opposing wall surfaces of the groove portion, and the first step portion and the second step portion. The heavy duty radial tire according to claim 1, wherein the depths of the radial tires are different from each other.