JPH09300916A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the early abrasion of the stepping on side of the block of a pneumatic tire in a tread pattern having many directional slant grooves arranged in a tire circumferential direction, by arranging an excavation in a side wall grounded later when the tire is normally rotated, out of two side walls forming the directional slant grooves. SOLUTION: In a pneumatic tire equipped with directional slant grooves extended in the form of a figure eight in a lateral direction, an excavation G is arranged in a side wall grounded later when the tire is normally rotated, out of two side walls of the directional slant grooves. Excavation height V measured in a tire radial direction on the side wall surface, is set in a range of 10 to 80% of the depth of the directional slant grooves, excavation width H measured in a direction where the directional slant grooves are extended on the side wall surface of the excavation G, is set in a range of 30 to 100% of block width measured in a direction where the directional slant grooves are extended, and excavation length S measured in a circumferential direction on the side wall surface of the excavation G, is set in a range of 10 to 30% of the block length measured in the circumferential direction, then the directional slant grooves are formed at a comparatively small inclination angle of 5 to 45 degrees against 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 large number of blocks formed by a large number of directional inclined grooves extending in the left-right direction with a pattern center between them and a connecting groove connecting adjacent directional inclined grooves. The present invention relates to a pneumatic tire having a so-called directional tread pattern provided on a tread, particularly a tire for trucks and buses, which has a side force which tends to occur in such a tire while maintaining drainage in a directional inclined groove. The present invention relates to improving uneven wear of blocks.

The term "depressing side of the block" as used herein will be referred to as "the stepping side of the block", which is one of the sides of the side formed by the inclined groove walls in one block. Sometimes refers to the side of the ground that comes first. Here, it should be noted that, when focusing on the inclined groove, the groove side wall of “the side which comes in contact with the ground after the tire rotates normally” corresponds to the “stepping side of the block”. The “block kick-out side” refers to the side of the side formed by the inclined groove walls in one block that comes into contact with the ground later during normal rotation of the tire.

[0003]

2. Description of the Related Art In recent years, in order to improve drainage, in the tire circumferential direction, a plurality of directional inclined grooves extending laterally in a figure 8 sandwiching a pattern center and connecting grooves connecting the adjacent directional inclined grooves are provided. A so-called directional tread pattern having a tread on a large number of blocks formed at intervals has been developed. Further, in order to improve drainage, the inclination angle of the directional inclined groove with respect to the circumferential direction is set to 5 degrees.
Attempts have been made to make relatively small angles of ~ 45 degrees. However, in such cases, in addition to the so-called heel-and-toe wear that occurs in a normal block pattern, the side force that occurs during cornering causes wear especially from the stepping side of the tire shoulder block to deteriorate the appearance and shorten the tread life. There are specific problems such as.

[0004]

However, with respect to the new problems as described above, in particular in the case of truck and bus tires, there is little experience and there is no sufficient solution.

Therefore, an object of the present invention is to provide a pneumatic tire having a directional tread pattern in which a large number of blocks are provided on a tread, and the inclination angle of the directional inclination groove with respect to the circumferential direction is a relatively small angle of 5 to 45 degrees. To provide a pneumatic tire, particularly a truck and bus tire, in which early wear on the stepping side of the block is suppressed.

[0006]

In order to achieve the above object, according to the present invention, a large number of directional inclined grooves are provided at intervals in the tire circumferential direction that extend in a left-right shape and sandwich a pattern center. A pneumatic tire having a tread pattern in which a block is formed by a connecting groove that connects the adjacent directional inclined grooves, (1) from a C-shaped tip of a pattern center of the directional inclined groove to a tread end The direction of normal rotation of the tire is determined so as to sequentially enter the ground contact surface, and (2) of the two side walls forming the directional inclined groove,
Adopted a structure in which the side wall that comes into contact with the ground later when the tire rotates normally is provided with a hollow.

[0007] Further, the carving height V measured in the tire radial direction on the side wall surface of the carving is 1 of the directional inclined groove depth.
It is preferably 0 to 80%.

Then, the gouging width measured in the extending direction of the directional inclined groove on the side wall surface of the gouging is 30 to 100% of the block width measured in the extending direction of the directional inclined groove. preferable.

In the present invention, it is preferable that the depth of the gouging on the side wall surface measured in the circumferential direction is 10 to 30% of the length of the block measured in the circumferential direction.

It is preferable that the directional inclined groove extends at a relatively small inclination angle of 5 to 45 degrees with respect to the circumferential direction because the drainage property is improved.

As for the block wear, it is known that the kick-out portion 2 of the block shown in FIG. 1 which is called so-called heel-and-toe wear is worn early, and in this regard, the arrangement of the sipes and the shape of the side wall of the groove are known. Various measures have been taken by changing the above. In the present invention, a new directional inclined groove is additionally provided, and the inclined groove is especially 5 to 4 in the circumferential direction.
This is to solve the early wear of the block step-in side 1 which is a problem with a tire of 5 degrees, and was made based on the following knowledge. That is, when a side force is applied during cornering, the stepping side 1 of the block receives a larger force than the kicking side 2 from the ground, but this force is required if the inclined groove has a low angle with respect to the circumferential direction. It is known that the more it grows, the larger it becomes. At the time of cornering, the block moves relative to the ground by receiving a force from the ground, so that the wear on the stepping side of the block naturally increases.

Here, of the two side walls forming the directional inclined groove, the side wall which comes into contact with the ground later when the tire rotates in the forward direction is provided with a hollow, that is, the depth of the side wall on the stepping side of the block is the kick of the block. The reason why the side wall on the projecting side is provided with a hollow is to reduce the block rigidity in this portion and to increase the shear deformation of the block. As a result, when the side force is applied, the local contact pressure at the end of the block is prevented from rising, and the occurrence of wear nuclei particularly at the initial stage of traveling is reduced.

The inclined groove does not have to be a straight line, and plural kinds of inclined grooves having different inclination angles and / or groove widths may be arranged on the tread. Also, the pattern center does not necessarily have to coincide with the tire equator.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Pneumatic tires according to embodiments of the present invention and conventional tires will be described below with reference to the drawings. In both cases, the tire size is 11R22.5 for trucks and buses. FIG. 1 is a tread pattern diagram of a pneumatic tire according to an embodiment of the present invention, which is a pneumatic tire in which directional inclined grooves 3 extending at an angle of 40 degrees with respect to a circumferential direction are provided on the tread across an equator line. .

FIG. 2 shows an embodiment of the present invention.
1A is a cross-sectional view taken along the line AA of the inclined groove (block) in FIG. 1, and FIG. As can be seen from this figure, the stepping side 1 of the block
Is provided on the side wall of the groove, and the height of the groove is V from the groove bottom.
It is provided and the gouging width is indicated by H.

FIG. 3 shows another embodiment of the present invention, in which (a) is a sectional view taken along the line AA of the inclined groove of FIG. 1, and (b) is shown.
And (c) are views of the side wall of the block viewed from the direction BB. The difference from FIG. 2 is that the gouging G does not start from the groove bottom and is located in the middle of the groove wall, and (b) is one gouging and (b) is two places.

Next, as shown in Table 1 for confirming the effect of the tire according to the present invention, as shown in Table 1 of the conventional example, which has no gouging, and the gouging G shown in FIG. ,
Example 2 was prepared in which the gouging G was provided as in (b). Two tires were prepared, and the entire circumference of the tire was divided into ⅓, and the tires were processed to be the conventional example, the example 1, and the example 2, respectively. These have a groove depth D of 16.5 mm and a block width W of 45.
mm, and the circumferential block length P is 43 mm.

In the test, the two wheels were mounted on the front wheels of a 2-D4 dump truck and run on a general road for 10,000 km to compare the occurrence of uneven wear. The comparison was performed on both shoulder side blocks, and the difference in wear between the stepping side and the kicking side of one block was calculated as the average of the two tires. The results are also shown in Table 1.

[0019]

[Table 1]

[0020]

As described above, the pneumatic tire according to the present invention can provide a tire in which early wear on the stepping side of the block due to side force generated during cornering is suppressed.

[Brief description of drawings]

FIG. 1 is a partially enlarged view of a tread pattern of a pneumatic tire according to the present invention.

FIG. 2 is a drawing of a block of a pneumatic tire according to the present invention. 1A is a cross-sectional view taken along the line AA of FIG. 1, and FIGS. 1B and 1C are views of the side wall of the block viewed from the direction BB.

FIG. 3 shows another embodiment according to the present invention,
(A) is the AA cross section of the inclined groove of FIG. 1, (b) and (c) are the figures which looked at the block side wall from the BB direction.

[Explanation of symbols]

 E Pattern center (tire equator line) TE Tread end P Block circumferential length W Block width G Groove part D Groove depth V Groove height H Groove width S Goop depth R Tire rotation direction 1 Block step side 2 Block start side 3 Directional inclined groove 4 Connection groove

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[Procedure amendment]

[Submission date] August 12, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2 is a drawing of a block of a pneumatic tire according to the present invention. 1A is a cross-sectional view taken along the line AA of FIG. 1, and FIG. 1B is a view of the side wall of the block viewed from the BB direction.

Claims (5)

[Claims] 1. A block is formed by a large number of directional inclined grooves which are arranged in a tire circumferential direction and extend in a left-right direction across a pattern center and which are arranged at intervals in the tire circumferential direction, and a connecting groove which connects the adjacent directional inclined grooves. In a pneumatic tire having a tread pattern, the forward rotation direction of the tire is determined so as to (1) sequentially enter the ground contact plane from the C-shaped tip of the pattern center of the directional inclined groove toward the tread end. ,
(2) A pneumatic tire characterized in that, of the two side walls forming the directional inclined groove, a side wall that comes into contact with the ground later when the tire rotates normally is provided with a hollow. 2. The depth of the hollowing measured on the side wall surface in the tire radial direction is 10 to 80 of the directional inclined groove depth.
The pneumatic tire according to claim 1, wherein the pneumatic tire is%. 3. The gouging width measured in the extending direction of the directional inclined groove on the side wall surface of the gouging is 30 to 100% of the block width measured in the extending direction of the directional inclined groove. The pneumatic tire according to claim 1 or 2, characterized in that. 4. The gouging depth measured in the circumferential direction on the side wall surface of the gouging is 10 to 10 times the block length taken in the circumferential direction.
The pneumatic tire according to claim 1, wherein the pneumatic tire is 30%. 5. The directional inclined groove is 5 to 4 in the circumferential direction.
The pneumatic tire according to any one of claims 1 to 4, wherein the pneumatic tire extends at a relatively small inclination angle of 5 degrees.