JPH0485108A - Pneumatic tire suppressed in offset abrasion - Google Patents

Abstract

PURPOSE:To suppress partial wear in a block by providing plural small holes, extended inward the tire radial direction, at the specified spaces apart at least around the block edge along the lateral groove. CONSTITUTION:A tread part T is provided with block rows 3-1 to 3-6 and blocks B1, B2... by circumferential main grooves 1-1 to 1-4... and lateral grooves 2. Plural small holes 4-l, 4-3 extended inward the tire radial direction are provided four each around the edge, along the lateral grooves 2, of each of the respective blocks B1, B2.... Small holes 4-2 are also provided one each at the edge along the circumferential grooves l, 1-3. The small hole 4 is so set that its depth is approximately 25-75% of the block height, its diameter (c) is approximately 0.5-3mm, the distance (a) from the edge is approximately 2-5mm, and the small hole spacing (b) is approximately 4-8mm.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an improvement of a pneumatic tire with a tread pattern, and more particularly to a pneumatic tire that effectively suppresses uneven wear. It is.

(Prior Art) Generally, various patterns such as a rib pattern, a block pattern, and a rib block pattern are formed on the tread portion of a tire, but in recent flat high-performance tires, a straight rib portion has a radial pattern. Block patterns with grooves and blocks are the mainstream,
This improves performance such as high-speed durability and drainage performance.

FIG. 1(a) shows a developed view of the tread of a pneumatic tire, and the tread surface T has a circumferential main groove (center groove) 1 along the circumferential center line O and a plurality of circumferential grooves on both sides thereof. 1
-1.1-2.1-3 and 1-4 are provided in parallel to the circumferential direction of the tire, resulting in a large number of ribs (block rows) 3
-1.3-2.3-3.3-4.3-5 and 3-6 are formed.

Furthermore, independent blocks B1, B2, . . . are formed in each block row by a large number of lateral grooves 2 arranged at predetermined intervals in a direction that intersects with these circumferential grooves.

Especially for tires with a specified rotation direction,
The lateral grooves 2 are arranged so as to be inclined in a herringbone shape toward the center line of the tire so that the blocks gradually come into contact with the road surface from the center area of the tire toward the tread edge during load transfer of the tire.

(Problem to be Solved by the Invention) However, in the conventional pneumatic tire described above, when running, shearing external force is applied to the stepping side, which contacts the road surface at the tip of the block, and the kicking side, which contacts the road surface later. Because of the difference, there was a problem in that the amount of wear especially on the kicking side of the block was large, causing uneven wear.

That is, as shown in FIG. 2(b), which is a hypothetical running diagram viewed from the cross-sectional direction taken along line XX in FIG. 2(a), when the tire rotates in the direction of arrow A, the depression side Ba of block B1 is In this case, the vertical ground pressure within the contact surface is large on the stepping side Ba and small on the kicking side Bb. Since the kicking side Bb is dragged against the road surface due to the low ground pressure and is subjected to a large external shearing force in the longitudinal direction, as a result, the amount of wear becomes the relationship of kicking side Bb > stepping side Ba, and the kicking side Bb
There was a problem in that the wear of the block was accelerated, resulting in uneven wear within the block.

Therefore, an object of the present invention is to solve the problems of the conventional pneumatic tires described above.

Therefore, an object of the present invention is to provide a pneumatic tire that effectively suppresses uneven wear within the block.

[Configuration of the Invention (Means for Solving the Problems) That is, the pneumatic tire of the present invention includes a pair of sidewalls and a tread extending over both sidewalls in a toroidal manner. A plurality of circumferential grooves that extend parallel to each other, a large number of lateral grooves that intersect with these circumferential grooves and are arranged at approximately equal intervals in the circumferential direction, and independent blocks that are divided by these groove groups. The tire is characterized in that a plurality of small holes extending toward the inside in the radial direction of the tire are provided at predetermined intervals at least near the edge of the block along the lateral groove.

(Function) The pneumatic tire of the present invention has a plurality of small holes extending radially inward of the tire at predetermined intervals, at least near the edge of the block along the lateral groove, so that the lateral groove of the block The rigidity of the edge along the block is relaxed, and as a result, the entire block receives an external shearing force in the longitudinal direction.

Especially for tires with a specified rotation direction,
By providing a small hole mainly in the kicking side edge of the block, it is possible to selectively relax the rigidity of the kicking side, which conventionally received a large amount of external shearing force, and reduce the amount of wear in this part. be.

Therefore, according to the pneumatic tire of the present invention, it is possible to effectively suppress uneven wear within the block, and it is ideal for high-speed running without causing deterioration of steering stability such as vibration or noise. It is possible to realize a tire with high performance.

(Example) Hereinafter, examples of the pneumatic tire of the present invention will be described in detail according to the drawings.

FIG. 1(a) is a developed view of the tread portion of the pneumatic tire of the present invention, and FIG. 1(b) is a block B in FIG. 1(a).
FIG.

Although parts other than the tread portion are not shown in FIG. 1, the other parts such as the radial carcass, belt layer, and sidewalls have a well-known structure.

That is, in FIG. 1, the tread portion T of the pneumatic tire of the present invention includes a pair of sidewalls (not shown) and a tread that spans both sidewalls and is connected in a toroidal manner. A plurality of circumferential grooves 1-1.1-2.1-3 and 1-4 are placed at predetermined intervals in the axial direction of the tire on both sides of the circumferential main groove (center groove) 1 along the direction center line, The ribs (block rows) 3-1.3-2.3-3.3-4.3-5 and 3 are provided linearly and endlessly in parallel to the circumferential direction.
-6 is formed.

Furthermore, independent blocks B1, B2, . . . are formed in each block row by a large number of lateral grooves 2 arranged at predetermined intervals in a direction intersecting the circumferential grooves.

In addition, circumferential main groove 1, circumferential groove 1-1.1-2.1-3
The groove width and depth of grooves 1-4 are the widest and deepest among the groove group.

Further, the lateral grooves 2 can be provided at an appropriate angle of 50 to 70 degrees from the center of the tread to the tread edge, and the width and depth of these grooves are equal to or greater than the circumferential grooves. It is as follows.

Especially for tires with a specified rotation direction,
The lateral groove 2 is inclined in a herringbone shape with respect to the circumferential direction, and is configured to contact the ground first in the direction forming an acute angle of the block.

Here, in the pneumatic tire of the present invention, a plurality of small holes 4 extending radially inward of the tire are provided at least near the edges along the lateral grooves 2 of each block B1, B2... It is characterized by being provided at intervals.

That is, as shown in an enlarged view in FIG. 1(b), each block, for example block B1, has four small holes 4-1 and 4-3, respectively, on both edges along the horizontal groove 2. Furthermore, one small hole 4-2 is provided at each edge along the circumferential grooves 1 and 1-3.

Note that the small holes 4-2 at the edges along the circumferential grooves 1 and 1-3 are not necessarily provided, and as described above, the lateral grooves 2 are inclined in a herringbone shape with respect to the circumferential direction, and the direction of rotation is specified. In a tire with a rotation direction specified in the direction of the arrow in FIG. 1(b), for example, a small hole 4-3 is provided only on the kicking side edge of block B1, and a small hole on the stepping side edge is provided. 4-1 can be omitted.

In addition, for tires for which the direction of rotation is not specified, small holes 4 can be provided on both the stepping side and kicking side of the block as shown in the figure, and in this case, both sides along the horizontal groove 2 of the block can be provided. Since the rigidity of both edges is reduced almost equally, compared to the case where the small hole 4 is not provided,
Demonstrates excellent uneven wear suppression effect.

Here, the planar shape of the small hole 4 can be selected from circular, elliptical, triangular, square, etc., its depth is 25-75% of the block height, and its diameter C is 0.5-3! A range of I11 is preferred.

Further, the distance a from the edge of the small hole 4 along the horizontal groove 2 is 2
~5mm, the distance between each small hole 4 is 4~8m+
It is preferable to set each value within the range of s.

By configuring as described above, the rigidity of the edge of the block along the lateral groove is relaxed, the amount of wear in this portion is reduced, and uneven wear within the block can be suppressed.

Next, the structure and effects of the pneumatic tire of the present invention will be explained in more detail using test examples.

(Test example) Tire size: 185/70R14RH79B.

Rim used: 5-1/2JX14, air pressure used = 1°8
The block pattern shown in FIG. 1 and (a) and (b) above was formed on the tread portion of a kg/cd radial tire, and this tire was evaluated.

Note that other structures such as the radial carcass and belt layer of the tire and manufacturing conditions were similar to those of conventional tires, so details will be omitted.

That is, in FIG. 1, the width of the tread portion T: 144 mm, and the groove width of the circumferential main groove 1: 8 mm. Om+s, depth=8.1w
Groove width of circumferential grooves 1-1.1-2.1-3 and 1-4: 5
．． 4-section, depth: 8.1 dragon, groove width of lateral groove 2: 4. O
A block pattern was formed with a fin depth of 6.6 mm and a depth of 6.6 mm.

Then, a planar circular small hole 4 with a diameter of 1.01 cm and a depth of 6.0 cm is formed on both edges along the horizontal groove 2 of each block, with the center 3 mm from the edge. A tire of the present invention was obtained by arranging the holes so that the distance between them was 0 mm and the distance between adjacent small holes was 4.5 fl.

On the other hand, for comparison, a conventional tire was obtained in the same manner except that no small hole 4 was provided.

The results of uneven wear evaluation of these two types of tires under the following conditions are shown in the following table.

(Evaluation method) The tires obtained above were installed on a vehicle with a load of 400 kg,
After subjecting the block to an actual vehicle running test under the following conditions, the difference in the amount of wear between the stepping side and the kicking/extending side of the block was measured and evaluated as an index (the larger the index, the greater the difference in the amount of wear).

Mileage: 30,000 km Travel route Ratio (%) of general roads, mountain slopes, and expressways
50 30 20 Speed (Sal/h
) 30-60 20-40 70-100 Table (Note) This is an index evaluation with the conventional tire set as 100. The larger the index, the larger the difference in the amount of wear between the stepping side and kicking side of the block.

From the above results, it is clear that uneven wear is effectively suppressed in the pneumatic tire of the present invention.

[Effects of the Invention] As described above in detail, the pneumatic tire of the present invention has at least a portion near the edge along the lateral groove of the block.
By providing multiple small holes at predetermined intervals that extend toward the inside of the tire in the radial direction, the rigidity of the edges along the lateral grooves of the block is relaxed, and as a result, the entire block receives external shearing forces in the longitudinal direction. Become.

Especially for tires with a specified rotation direction,
By providing a small hole in the edge of the kicking side of the block, it is possible to selectively relax the rigidity of the kicking side, which conventionally receives a large amount of external shearing force, and reduce the amount of wear in this area. .

Therefore, according to the pneumatic tire of the present invention, it is possible to effectively suppress uneven wear within the block, and it is ideal for high-speed running without causing deterioration of steering stability such as vibration or noise. It is possible to realize a tire that has the desired performance.

[Brief explanation of drawings]

FIG. 1(a) is a developed view of the tread portion of the pneumatic tire of the present invention, and FIG. 1(b) is a block B in FIG. 1(a).
FIG. 2(a) is a developed view of a tread portion of a conventional pneumatic tire, and FIG. 2(b) is an explanatory cross-sectional view taken along line X--X in FIG. 2(a). T......Tread part 1......Circumferential main groove 1-1...Circumferential groove 1-2...〃 1-3...〃 1 -4・-・ 〃 2・・・・・・・・・ Lateral groove 3-1... Block row 3-2... 〃 3-3... 〃 3-4... 〃 3- 5... 〃 3-6.../l B1...Block B 2...... 〃 4......Small hole 4-1...Small hole on the stepping side 4-2...Kicking side small hole 0......Circumferential center line

Claims (1)

[Claims] A pair of sidewalls and a tread that spans both sidewalls are connected in a toroidal manner, and the tread has a plurality of circumferential grooves that extend parallel to each other at predetermined intervals in the axial direction, and a plurality of circumferential grooves that intersect with these circumferential grooves and that extend in the circumferential direction. In a tire including a large number of lateral grooves arranged at approximately equal intervals, and independent blocks separated by groups of these grooves, at least near the edges of the blocks along the lateral grooves, radially inside the tire. A pneumatic tire that suppresses uneven wear, characterized in that a plurality of small holes extending toward each other are provided at predetermined intervals.