JPH08318711A - Pneumatic tire provided with block pattern - Google Patents

Abstract

PURPOSE: To reduce a tyre noise by forming a sipe on an acute angle corner part grounded in advance at the tire rolling time so as to divide the acute angle corner part. CONSTITUTION: Periphery direction grooves 1 by every two in right/left both sides are formed while sandwiching the equator surface of a tyre and slant grooves 3 extended slantingly between them with about 45 deg. angle for the periphery direction are formed at some intervals in the periphery direction and blocks 5 having the acute angle corner part are formed by the periphery direction grooves 1 and the slant grooves 3. Further, slant grooves 2 extended slantingly with about 60 deg. angle for the periphery direction between the periphery direction grooves 1 and tread end part are formed at some intervals in the periphery direction and blocks 6 having the acute angle corner part are formed by the periphery direction grooves 1 and the slant grooves 2. Sipes 4 are provided on the acute angle corner parts of the blocks 5 and blocks 6, which are divided. Consequently, the rigidity of the acute angle corner parts for radiating the largest noise is weakened and a radiation noise generated by the collision with a road surface at the ground and step in time is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having a pattern of blocks having sharp corners.

[0002]

2. Description of the Related Art Generally, a pneumatic tire having a block pattern generates a larger amount of noise during running than a pneumatic tire having a rib pattern, and it is strongly required to reduce the noise. ing. Pitch variation has been known as a technique for reducing tire noise, and has been put to practical use. This is a method for reducing tire noise based on the theory of frequency modulation, in which the circumferential length (pitch) of the minimum unit pattern that constitutes the pattern is set to two or more types, and This is a technique for reducing tire noise, in which the noise generated from the tire is dispersed into many sidebands having a low sound pressure level by appropriately arranging the tires.

[0003]

Strictly speaking, however, this pitch variation technique is a technique for making tire noise hard to hear by widely distributing the frequency of tire noise, and never the energy of noise itself. It is not decreasing.

The object of the present invention is to solve the above problems of the prior art and to reduce the energy of noise generated from a pneumatic tire having a pattern of blocks having sharp corners. It is to reduce tire noise in a practical sense.

[0005]

In order to achieve the above object, the pneumatic tire of the present invention is a pneumatic tire provided with a pattern consisting of blocks having sharp corners. A pneumatic tire characterized in that a sipe is formed at least in an acute-angled corner portion that comes into contact with the tire when the tire rolls first, so as to divide the acute-angled corner portion.

In order to achieve the above object, in the pneumatic tire of the present invention, it is preferable that the length of the sipe formed in the sharp corner is 50% or less of the diagonal length of the sharp corner. Further, it is preferable that the depth of the sipe formed in the acute corner portion is 10 to 80% of the depth of the groove adjacent to the acute corner portion.

[0007]

[Function] Tire noise includes "groove air pumping noise", "block (or lug) vibration noise" and "other noises (frictional ground noise, noise caused by vibration of the tire due to uneven road surface, or However, the former two sources are putters such as lugs, ribs or blocks formed on the tread surface of the tire by grooves. And block
In a tire provided with a pattern, the block vibration sound tends to be loud. In a pneumatic tire with a block pattern, the block collides with the road surface when the discontinuous portion of the tread rubber surface that is the boundary between the blocks touches the road surface when the tire rolls, and the block vibrates due to the impact force. And emits sound (block excitation sound). The sound emission acts as a speaker, so to speak, by vibrating the tire sidewalls and tread surface.

In a pneumatic tire having a pattern composed of blocks having sharp corners, the sharp corners that come into contact with the ground first when the tire rolls collide with the road surface when the vehicle is just stepping on the ground, and the impact force causes a block. Vibrates and emits the loudest sound. The pneumatic tire of the present invention, as described above, in a pneumatic tire having a pattern consisting of a block having an acute corner, among the acute corners,
Since the sipe is formed at least in the acute-angled corner portion that comes into contact with the ground first when the tire rolls, the rigidity of the acute-angled corner portion that emits the loudest sound is weakened. As a result, the input level to the block when the vehicle collides with the road surface when stepping on the ground is reduced, and the level of radiated sound is also reduced.

In the pneumatic tire of the present invention, the length of the sipe formed in the acute corner portion is 50% of the diagonal length of the acute corner portion.
The following is preferred. When the length of the sipe formed in the acute-angled corner becomes larger than 50% of the diagonal length of the acute-angled corner, most of the block is divided by the sipe, the block rigidity is reduced, and the steering stability of the tire is reduced. Performance decreases.

Further, in the pneumatic tire of the present invention, it is preferable that the depth of the sipe formed in the acute corner portion is 10 to 80% of the depth of the groove adjacent to the acute corner portion. When the depth of the sipe is smaller than 10% of the groove depth of the adjacent groove, the effect of reducing the input level to the block when colliding with the road surface when stepping on the ground becomes extremely small, while the depth of the sipe is adjacent. If the groove depth is greater than 80% of the groove depth, the rigidity of the sharp corners decreases and the steering stability of the tire decreases.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described with reference to the drawings. FIG. 1 is a tread pattern of a pneumatic tire for passenger cars according to the embodiment of the present invention, in which a tire size is 225 / 60R16. Example tread
The pattern has a total of four circumferential grooves 1 formed on each of the left and right sides on both sides of the equatorial line of the tire, and extends between the circumferential grooves 1 at an angle of about 45 degrees with respect to the circumferential direction. Groove 3
Are formed at intervals in the circumferential direction, and the circumferential groove 1 and the inclined groove 3 form a block 5 having an acute-angled corner portion. Further, between the circumferential groove 1 and the tread end, inclined grooves 2 extending at an angle of about 60 degrees with respect to the circumferential direction are formed at intervals in the circumferential direction, and the circumferential groove 1 and the inclined groove are formed. Two
And form a block 6 having an acute corner. The sipes 4 are provided at the sharp corners of the blocks 5 and 6, and the sharp corners of the blocks 5 and 6 are divided. The sipe 4 has a cross-sectional shape as shown in the sectional view taken along the line A-A, and the length L of the sipe is about 30% of the diagonal length of the acute angle corner and the depth d of the sipe is a groove adjacent to the acute angle corner. The depth D is about 50%.

FIG. 2 shows an example of a modified design of the blocks 5 and 6 having sharp corners, which may be triangular, circular or rectangular. FIG. 3 is an example of a modified design of the block 5 and the block 6 having sharp corners and the sipe 4.

The pneumatic tire of the conventional example is the same as the pneumatic tire of Example 1 except that the sipes 4 are not provided at the sharp corners of the blocks 5 and 6 having sharp corners.

A tire noise evaluation test was carried out on the pneumatic tires of the examples according to the present invention and the pneumatic tires of the conventional examples based on the automobile standard tire noise test method JASOC606. The test conditions are a rim of 8 J × 16, a tire internal pressure of 3.1 kgf / cm ² , a load of 500 kgf, and a speed of 60 km / h. The measurement item is noise (sound pressure level) in all frequency bands.

According to the evaluation results, it was found that the noise of the pneumatic tires of the examples according to the present invention was 1 to 1.5 dB lower than the noise of the pneumatic tires of the conventional examples.

[0016]

From the above evaluation results, it can be seen that the pneumatic tires of the examples according to the present invention have significantly reduced tire noise as compared with the pneumatic tires of the conventional examples.

[Brief description of drawings]

FIG. 1 is a tread pattern diagram of a pneumatic tire according to the present invention.

FIG. 2 is a modified design example of a block having an acute-angled corner portion of a pneumatic tire according to the present invention.

FIG. 3 is a modified design example of a block and a sipe having an acute-angled corner portion of a pneumatic tire according to the present invention.

[Explanation of symbols]

 1 circumferential groove 2 inclined groove 3 inclined groove 4 sipe 5 block 6 block

Claims (3)

[Claims] 1. A pneumatic tire having a pattern comprising a block having sharp corners, wherein the sharp corners are divided into at least sharp corners that are grounded first when the tire rolls. A pneumatic tire characterized in that a sipe is formed so that 2. The pneumatic tire according to claim 1, wherein the length of the sipe formed in the acute corner portion is 50% or less of the diagonal length of the acute corner portion. 3. The air according to claim 1, wherein the depth of the sipe formed in the acute corner portion is 10 to 80% of the depth of the groove adjacent to the acute corner portion. Included tires.