JPH1024706A - Pneumatic tire with asymmetric v-shaped groove - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce tire noises without applying harmful effects to the external appearance and manufacturing cost in a pneumatic tire having a pattern containing cross sectional direction grooves extended at a relatively large tilt angle in the peripheral direction. SOLUTION: Many V-shaped grooves extended in the V-shape to the right and left from the vicinity of the tire equator line EL are arranged at intervals in the tire peripheral direction. The offset quantity of the pattern center PC connecting the apexes of the V-shaped grooves from the tire equator line EL is set to 1-10% of the tread width TW, and many cross sectional direction grooves 2 opened at the right and left tread ends TE and extended from the opening ends in the tread cross sectional direction toward the pattern center PC are arranged asymmetrically on the right and left at intervals in the tire peripheral direction. A tread pattern drifted by 35-65% of the pitch length PL which is the peripheral direction interval of the cross sectional direction grooves 2 in the peripheral direction at the right and left tread ends TE is provided.

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 tread in which a large number of V-shaped grooves extending in a V-shape from the vicinity of the tire equator line to the left and right are arranged at intervals in the circumferential direction of the tire. A plurality of pneumatic tires with a pattern, more specifically opening at the left and right tread ends, extending transversely from the opening ends toward the pattern center in the tread direction and opening into the V-shaped groove; Are arranged at intervals in the circumferential direction of the tire, and the V-shaped grooves are formed at 5 to 40 degrees with respect to the circumferential direction, preferably 1 to 40 degrees.
The tread pattern extends at a relatively small angle of inclination of 0 to 20 degrees and the transverse groove extends at a relatively large angle of inclination of 45 to 90 degrees, preferably 60 to 80 degrees with respect to the circumferential direction. The present invention relates to a pneumatic tire provided.

[0002]

2. Description of the Related Art As described above, a large number of V-shaped grooves which extend right and left from the vicinity of the tire equator line and extend at a relatively small inclination angle with respect to the circumferential direction, and a pattern center from the left and right tread ends. A pneumatic tire having a pattern including a transverse groove extending in a cross direction toward the tread and extending at a relatively large inclination angle with respect to a circumferential direction has a noise (pattern noise) generated from the tire during traveling. Since it is large, there is a strong demand to reduce this noise (pattern noise).

[0003] As a technique for reducing tire noise (pattern noise), pitch variations are conventionally known and have been put to practical use. This is a method of reducing tire noise (pattern noise) based on frequency modulation theory or the like. The circumferential length (pitch) of a pattern as a minimum unit constituting a pattern is set to two or more kinds of lengths and is appropriately set. , The peak of a large sound pressure level which is concentrated at a certain frequency when arranged at one kind of pitch is increased to a lot of lower sound pressure levels. This is a method of reducing tire noise (pattern noise) by dispersing the tire into sideband waves.

[0004]

According to the above-mentioned pitch variation technique, strictly speaking, the energy of the noise is not reduced, but the frequency of the noise is widely dispersed to reduce the tire noise (pattern noise). It is a technique to make it difficult to hear. In addition, a large number of V-shaped grooves extending from the vicinity of the tire equator line to the left and right and extending at a relatively small inclination angle with respect to the circumferential direction, and extending in the transverse direction of the tread from the left and right tread ends toward the pattern center. In a pneumatic tire having a pattern including a transverse groove extending at a relatively large inclination angle with respect to a circumferential direction, a conventionally known pitch and
Tire noise (pattern /
Noise), the groove extending straight at an angle to the circumferential direction becomes zigzag and the appearance becomes poor, and the number of engraving models for producing a mold for vulcanizing the tire becomes extremely large. The production cost is too high and cannot be easily adopted. That is, two or more types of pitches, which are circumferential intervals of the slightly directional inclined grooves (patterns of the minimum unit constituting the pattern), are set on the periphery of the tire tread so that tire noise (pattern noise) is minimized. If the grooves are optimally arranged, the grooves extending straight at an angle inclined with respect to the circumferential direction become zigzag.

An object of the present invention is to solve the above-mentioned disadvantages of the prior art, and to provide a large number of V-shaped grooves extending at a relatively small inclination angle with respect to the circumferential direction and the left and right tread ends toward the pattern center. Pneumatic tire having a pattern that includes a transverse groove extending in the cross direction of the tread and extending at a relatively large inclination angle with respect to the circumferential direction, without adversely affecting the appearance of the tire and the manufacturing cost of the tire. It is to reduce.

[0006]

In order to achieve the above object, in the pneumatic tire of the present invention, a large number of V-shaped grooves extending in a V-shape from the vicinity of the tire equator line to the left and right are provided in the tire circumferential direction. In a pneumatic tire having a tread pattern arranged at intervals, (1) the offset amount of the pattern center connecting the apex of the V-shaped groove from the tire equator line is 1 to 10% of the tread width. (2) Opening at the left and right tread ends, extending in the cross direction of the tread from the opening end toward the pattern center, and a plurality of transverse grooves opening in the V-shaped grooves are spaced apart in the tire circumferential direction. (3) the transverse groove is arranged asymmetrically in the left-right direction,
A pneumatic tire provided with a tread pattern, characterized in that at right and left tread ends, the tire is circumferentially shifted by 35 to 65% of a pitch length, which is a circumferential interval of the transverse grooves.

To achieve the above object, the V-shaped groove extends at a relatively small inclination angle with respect to the circumferential direction, and the transverse groove extends at a relatively large inclination angle with respect to the circumferential direction. Is preferred.

In order to achieve the above object, the V-shaped groove extends at a relatively small inclination angle of 5 to 40 degrees with respect to the circumferential direction, and the transverse groove extends at 45 to 90 degrees with respect to the circumferential direction. It preferably extends at a relatively large angle of inclination.

In order to achieve the above object, the V-shaped groove extends at a relatively small inclination angle of 10 to 20 degrees with respect to the circumferential direction, and the transverse groove extends at 60 to 80 degrees with respect to the circumferential direction. It preferably extends at a relatively large angle of inclination.

[0010] In order to achieve the above object, it is preferable that the V-shaped groove extends right and left at substantially the same inclination angle with respect to the circumferential direction with respect to the pattern center.

[0011] In order to achieve the above object, it is preferable that the amount of circumferential displacement of the transverse grooves arranged asymmetrically in the left-right direction gradually decreases from the tread end toward the pattern center.

[0012]

DETAILED DESCRIPTION OF THE INVENTION Tire noise (pattern noise)
Include a pattern air pumping sound and a pattern excitation sound. The pattern air pumping sound is generated by the so-called pumping action, in which the grooves of the tread pattern formed on the tire tread compress air when stepping on the ground contact and release it when it comes off the ground contact. Noise. The frequency of this noise depends on the length of the groove in the ground contact portion, and is substantially constant irrespective of the running speed of the vehicle, that is, the rotational speed of the tire. The pattern excitation sound is noise radiated when a discontinuous portion of the tread pattern formed on the tire tread collides with a road surface when the tire comes into contact with the ground, and the tire is vibrated by the impact force. The radiation of the noise acts as a diaphragm on the side wall and tread surface of the tire, and acts just like a speaker. The frequency of this noise depends on the running speed of the vehicle, that is, the rotational speed of the tire, and as the speed increases, high-frequency noise becomes proportional to the noise. The tire targeted by the present invention, i.e., a large number of V-shaped grooves extending at a relatively small inclination angle with respect to the circumferential direction and extending in the cross direction of the tread from the left and right tread ends toward the pattern center, and extending in the circumferential direction. In a pneumatic tire provided with a pattern including a large number of transverse grooves extending at a relatively large inclination angle, the pattern excitation sound of the latter is louder than the pattern air pumping sound of the former.

When the tire rolls, a block edge formed by a large number of V-shaped grooves and a large number of transverse grooves collides with a road surface to generate an impact. The tires vibrate together with the impact sounds from a number of blocks in the ground contact surface, and tire noise (pattern excitation sound) is emitted. In the pneumatic tire of the present invention, the configuration is as described above, in particular, the transverse grooves are arranged asymmetrically in the left and right, at the left and right tread ends, approximately half the pitch length which is the circumferential interval of the transverse grooves In other words, since the tires are displaced in the circumferential direction by 35 to 65%, the impact noises from the left half and the right half blocks in the ground contact surface cancel each other, and as a result, the tire noise (the impact noise from the blocks) The pattern excitation sound) is reduced.

In the pneumatic tire of the present invention, the angle of inclination of the V-shaped groove is preferably from 5 to 40 degrees, more preferably from 10 to 20 degrees. If this angle is too small, the block formed between the V-shaped grooves will be small, the block rigidity will be insufficient, and steering stability on a dry road surface will be reduced. Therefore, in order to increase the block size in order to increase the rigidity of the block, the pitch of the V-shaped groove must be set to a large value. In this case, the number of pitches must be reduced. The noise of the frequency component becomes conspicuous. If the angle of the V-shaped groove is too large, the drainage performance of the V-shaped groove on a wet road surface is reduced, and the function of preventing or suppressing the hydroplaning phenomenon is reduced. Further, the intersection angle between the V-shaped groove and the transverse groove becomes small, the rigidity of the block becomes insufficient, the steering stability on a dry road surface is reduced, and uneven wear is liable to occur.

In the pneumatic tire of the present invention, the inclination angle of the transverse groove is preferably 45 to 90 degrees.
More preferably, it is 0 to 80 degrees. If the angle of the transverse groove is too small, the intersection angle between the V-shaped groove and the transverse groove becomes small, the rigidity of the block becomes insufficient, the steering stability on a dry road surface decreases, and uneven wear easily occurs. Become. Further, the size of the block formed between the V-shaped groove and the transverse groove is reduced, and the rigidity of the block is insufficient, and the steering stability on a dry road surface is reduced. If the angle of the transverse groove is too large, the noise increases.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments according to the present invention, conventional examples and comparative examples 1 and 2 will be described with reference to the drawings. Each tire size is 225 / 50ZR16.

FIG. 1 shows a tread pattern of a conventional pneumatic tire for a passenger car, in which a number of V-shaped grooves 1 extending in a V-shape from side to side with respect to the tire equator line EL are arranged at intervals in the circumferential direction of the tire. It has a tread pattern that is arranged in a vertical position. Since the pattern center PC connecting the vertices of the V-shaped groove 1 is located on the tire equator EL, the offset amount of the pattern center PC from the tire equator EL is zero. A large number of transverse grooves 2 are opened at the left and right tread ends TE, extend in the transverse direction of the tread from the open end toward the pattern center PC, and open to the V-shaped groove 1 at intervals in the tire circumferential direction. Have been. The transverse grooves 2 are arranged symmetrically. The V-shaped groove 1 extends at a relatively small inclination angle with respect to the circumferential direction, the transverse groove 2 extends at a relatively large inclination angle with respect to the circumferential direction, and the V-shaped groove 1 has an inclination angle of 30 degrees. The inclination angle of the transverse groove 2 is 65 degrees.

FIG. 4 shows a tread pattern of an embodiment of a pneumatic tire for a passenger car according to the present invention, in which a number of V-shaped grooves 1 extending in a V-shape from the vicinity of the tire equator line EL are formed in the circumferential direction of the tire. Treads spaced apart from each other
Has a pattern. Since the offset amount D of the pattern center PC connecting the apex of the V-shaped groove 1 from the tire equator line EL is 4 mm and the tread width TW is 180 mm, D / TW = 2.2%. Open at the left and right tread ends TE, and open the pattern center P
A number of transverse grooves 2 extending in the cross direction of the tread toward C and opening into the V-shaped groove 1 are arranged at intervals in the tire circumferential direction. The pitch length PL, which is the circumferential interval between the transverse grooves 2, is 30 mm, and the transverse grooves 2 are arranged asymmetrically in the left and right directions, and at the left and right tread ends, 50% of the pitch length PL of the transverse grooves 2 Only in the circumferential direction. The V-shaped groove 1 extends at a relatively small inclination angle with respect to the circumferential direction, the transverse groove 2 extends at a relatively large inclination angle with respect to the circumferential direction, and the V-shaped groove 1 has an inclination angle of 30 degrees.
The inclination angle of the transverse groove 2 is 65 degrees.

FIG. 2 shows a tread pattern of the pneumatic tire for a passenger car of Comparative Example 1, in which a V-shaped groove 1 and a transverse groove 2 are arranged asymmetrically in the left and right direction and are shifted by 1/2 pitch in the circumferential direction. Except for this, the tread pattern is almost the same as the tread pattern of the conventional tire shown in FIG.

FIG. 3 shows a tread pattern of the pneumatic tire for a passenger car of Comparative Example 2, in which the offset amount D from the tire equator line EL of the pattern center PC connecting the vertices of the V-shaped groove 1 is 5 mm. The tread pattern is substantially the same as the tread pattern of the conventional tire shown in FIG. 1 except that the inclination angle of the V-shaped groove 1 is 30 degrees.

The above-described pneumatic tires of the examples according to the present invention, conventional pneumatic tires, and pneumatic tires of Comparative Examples 1 and 2 were subjected to comparative evaluation tests of tire noise. Test conditions were as follows: rim 8J × 16, tire internal pressure 210 kPa, load 400 kg, speed 40 km /
h, 60 km / h, 80 km / h and 100 km / h.

As a result of the comparative evaluation test, the sound pressure level of the tire noise of the conventional pneumatic tire was 82.6 db (A).
Thus, the pneumatic tires of Comparative Examples 1 and 2 are 81.6 db.
(A) to 82.0 db (A), but the sound pressure level of the pneumatic tire of the embodiment according to the present invention is 79.0 db.
(A). In other words, as compared with the sound pressure level of the tire noise of the conventional pneumatic tire, the pneumatic tires of Comparative Examples 1 and 2 have reduced tire noise by only 1.0 to 0.6 db (A), In the pneumatic tire of the embodiment according to the present invention, a significant reduction of 3.6 db (A) is achieved.

[0023]

From the results of the above comparative evaluation test, it can be seen that the pneumatic tire of the embodiment according to the present invention has significantly reduced tire noise as compared with the conventional pneumatic tire.

[Brief description of the drawings]

FIG. 1 is a tread pattern diagram of a conventional pneumatic tire.

FIG. 2 is a tread pattern diagram of a pneumatic tire of a comparative example.

FIG. 3 is a tread pattern diagram of a pneumatic tire of a comparative example.

FIG. 4 is a tread pattern diagram of a pneumatic tire according to the present invention.

[Explanation of symbols]

 D Offset amount EL Tread equatorial line PC Pattern center PL Pitch length TE Left and right tread ends 1 V-shaped groove 2 Transverse groove

Claims (8)

[Claims] 1. A pneumatic tire having a tread pattern in which a number of V-shaped grooves extending in a V-shape from right to left from the vicinity of the tire equator line are arranged at intervals in the tire circumferential direction. The offset amount of the pattern center connecting the apex of the V-shaped groove from the tire equator line is 1 to 10% of the tread width. (2) The pattern center is opened at the left and right tread ends, and the pattern center is opened from the opening end. A number of transverse grooves extending in the cross direction of the tread and opening to the V-shaped groove are arranged at intervals in the tire circumferential direction. (3) The transverse grooves are arranged asymmetrically in the left and right directions, and A pneumatic tire having a tread pattern, characterized in that at a tread end, the circumferential groove is circumferentially shifted by 35 to 65% of a pitch length, which is a circumferential distance between the transverse grooves. 2. The V-shaped groove extends at a relatively small inclination angle with respect to the circumferential direction, and the transverse groove extends at a relatively large inclination angle with respect to the circumferential direction. 2. The pneumatic tire according to 1. 3. The pneumatic tire according to claim 1, wherein the V-shaped groove has an inclination angle of 5 to 40 degrees. 4. The inclination angle of the transverse groove is 45 to 90.
The pneumatic tire according to any one of claims 1 to 3, wherein the degree is a degree. 5. The pneumatic tire according to claim 1, wherein the V-shaped groove has an inclination angle of 10 to 20 degrees. 6. The inclination angle of the transverse groove is 60 to 80.
The pneumatic tire according to any one of claims 1 to 5, wherein 7. The pneumatic pneumatic pump according to claim 1, wherein the V-shaped groove extends right and left across the pattern center at substantially the same inclination angle with respect to the circumferential direction. tire. 8. The pneumatic tire according to claim 1, wherein an amount of circumferential deviation of the transverse grooves arranged asymmetrically in the left and right direction gradually decreases from a tread end toward a pattern center.