JP2006151314A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of reducing columnar pipe resonance sound generated from a tire circumferential groove without reducing hydroplaning performance. <P>SOLUTION: A helically continuous recession/projection 20 forming an angle of 30-60° with a tire axial direction is provided on a groove bottom surface 10b at a groove 10a and the groove bottom surface 10b of a circumferential groove 10 formed on a tread part 2 of the pneumatic tire 1. A stream of air is disturbed to reduce columnar pipe resonance sound by the helical recession/projection 20 provided in an oblique direction relative to an extension direction of the circumferential groove 10. Water intruded into the circumferential groove 10 is discharged while rotation along the helical recession/projection 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly, to reduction of tire noise caused by air column resonance noise of a circumferential groove formed in a tire tread portion.

In recent years, with the quietness of vehicles, the contribution of noise caused by tires to automobile noise has increased, and the reduction thereof has been demanded. Above all, tire noise at a high frequency, particularly around 1000 Hz, is a main cause of noise outside the vehicle, and countermeasures for reducing the noise are indispensable for dealing with environmental problems.
Since the tire noise around 1000 Hz is generated by the resonance phenomenon of the tubular cavity formed between the tire and the road surface when the circumferential groove formed on the surface of the tire tread is grounded, generally, the air column tube It is said to be a resonance sound.
As a technique for suppressing the air column resonance noise, it has been well known that the number and volume of the circumferential grooves are conventionally reduced. However, in this technique, the drainage function by the circumferential grooves is lowered. This causes a decrease in wet performance as typified by the hydroplaning phenomenon.
As another method, there is a method of widening the circumferential groove width contrary to the above method (see, for example, Patent Document 1). However, in this case, there is a problem in that it is difficult to achieve both the steering stability on the dry road surface and the limit grip characteristics, because the contact area is greatly reduced and a large step is generated in the distribution in the width direction of the contact pressure. .

Therefore, as shown in FIGS. 3 (a) and 3 (b), the groove wall surface 10a is undulated by providing irregularities 11 in the tire radial direction and the circumferential direction of the entire groove wall surface 10a of the circumferential groove 10. As shown in FIG. 4, a method for reducing the noise and sound pressure level has been proposed, for example, by arranging the small concave portions 12 in a distributed manner on the groove wall surface 10a and the groove bottom surface 10b of the circumferential groove 10. That is, the presence of the irregularities 11 and the small recesses 12 fluctuates the cross-sectional area of the air flowing into the contact area of the circumferential groove 10, thereby inhibiting the generation of standing waves in the air column, and Since the noise in the pillar is reflected by the unevenness 11 and the small recess 12 and interferes with each other, the noise sound pressure level can be reduced. Further, even if the circumferential groove 10 has the unevenness 11 and the small recessed portion 12, the groove width and depth thereof are not changed, so that the tire noise can be reduced without reducing the wet performance (for example, Patent Documents 2 and 3).
Japanese Patent No. 2698739 JP-A-4-334606 Japanese Patent Laid-Open No. 7-17217

  However, in the method in which the concave and convex portions 11 are provided on the groove wall surface 10a or the small concave portions 12 are dispersed and arranged on the groove wall surface 10a and the groove bottom surface 10b of the circumferential groove 10, the reduction of the air column resonance noise is improved. Since the unevenness 11 and the small recesses 12 must be distributed so as to inhibit the flow of water in the groove, the water in the premises cannot be drained quickly, and therefore the groove width of the circumferential groove 10 Even if the depth was the same, it could not be said that the hydroplaning performance was sufficiently secured.

  The present invention has been made in view of conventional problems, and provides a pneumatic tire that can reduce air columnar resonance generated from a tire circumferential groove without reducing hydroplaning performance. With the goal.

As a result of intensive studies, the inventors have provided spiral continuous irregularities (undulations) on the wall surface and bottom surface of the circumferential groove, and the spiral continuous irregularities formed at an angle with the circumferential groove. By disturbing the air flow in the circumferential groove by the above, it becomes possible to reduce the air column resonance noise caused by the pumping action of the air, and the water that has entered the groove along the spiral Since the water can be drained quickly while rotating, the present inventors have found out that the air columnar resonance can be reduced without degrading the hydroplaning performance, and have arrived at the present invention.
That is, the invention according to claim 1 of the present application is a pneumatic tire having a circumferential groove extending along the tire circumferential direction on the tread surface, and the unevenness spirally continuing on the groove wall surface and the groove bottom surface of the circumferential groove. Is provided.
According to a second aspect of the present invention, the height of the unevenness is changed in the circumferential groove.
According to a third aspect of the present invention, the angle formed by the extending direction of the spiral irregularities at the groove bottom and the tire axial direction is in the range of 30 to 60 degrees.
According to a fourth aspect of the present invention, the height of the convex portion is 0.2 to 1.0 mm.
The invention described in claim 5 is such that the width of the convex portion is 0.2 to 1.0 mm.
The invention described in claim 6 is such that the width of the recess is 0.2 to 1.0 mm.

  According to the present invention, since the spiral groove is provided on the wall surface and bottom surface of the circumferential groove, the air flow in the circumferential groove is disturbed to reduce air columnar resonance noise during tire travel. In addition, since the water in the groove can be quickly drained along the spiral irregularities, tire noise can be effectively reduced without degrading the hydroplaning performance.

Hereinafter, the best mode of the present invention will be described with reference to the drawings.
1A and 1B are schematic views showing details of a ground contact shape and a circumferential groove of a pneumatic tire according to the best mode of the present invention, in which 10 is a tread portion of the pneumatic tire 1. Reference numeral 20 denotes a circumferential groove 20 formed on the groove wall surface 10 a and the groove bottom surface 10 b of the circumferential groove 10. In this example, the angle θ formed by the extending direction of the spiral continuous unevenness 20 on the groove bottom surface 10b of the circumferential groove 10 and the tire axial direction is within a range of 30 to 60 degrees, and the convex portion 20a. The height is 0.2 to 1.0 mm, the width is 0.2 to 1.0 mm, and the width of the recess 20b is 0.2 to 1.0 mm.
As described above, the spiral continuous unevenness 20 is formed obliquely with respect to the tire circumferential direction, so that air flowing into the contact area of the circumferential groove 10 flows through the upward oblique unevenness 20. Is disturbed. Therefore, the standing wave generated in the tubular cavity formed between the tire and the road surface can be suppressed, and air columnar resonance noise can be reduced.
Further, water having a viscosity higher than that of air is drained through the circumferential groove 10 while rotating along the spiral irregularities 20, so that even if there are the groove wall surface 10a, the groove bottom surface 10b, and the irregularities 20, Hydroplaning performance is not degraded.

At this time, it is preferable that the angle θ formed by the extending direction of the spiral continuous unevenness 20 and the tire axial direction is within a range of 30 to 60 degrees. That is, if the angle θ is less than 30 degrees, the angle between the direction of the water entering the circumferential groove 10 and the unevenness 20 becomes large, and the water cannot be drained quickly. It is difficult to maintain the performance, and when the angle θ exceeds 60 degrees, the angle of the unevenness 20 and the angle of the circumferential groove 10 are close to each other, so that the air flow is not sufficiently disturbed, and the air column Since the effect of reducing the tube resonance sound is reduced, the angle θ is preferably in the range of 30 to 60 degrees.
The height and width of the convex portion 20a and the width of the concave portion 20b are preferably 0.2 to 1.0 mm. That is, when the height and width are less than 0.2, the effect of allowing the water entering the circumferential groove 10 to pass through the groove while rotating and the effect of disturbing the air flow are sufficiently obtained. In addition, if the height and width exceed 1.0 mm, the unevenness is so large that cracks may occur in the circumferential groove 10 and the durability may deteriorate, so the height and width of the convex portion 20a. And the width | variety of the said recessed part 20b has good 0.2-1.0 mm.

  Thus, according to this best mode, the groove wall surface 10a and the groove bottom surface 10b of the circumferential groove 10 formed in the tread portion 2 of the pneumatic tire 1 are separated from the tire axial direction by 30 to the groove bottom surface 10b. A spiral concavity and convexity 20 having an angle of 60 degrees is provided, and the air flow is disturbed by the spiral concavity and convexity 20 provided obliquely with respect to the extending direction of the circumferential groove 10 to disturb the air flow. While reducing resonance noise, water entering the circumferential groove 10 is drained while rotating along the spiral irregularities 20, so that the hydroplaning performance is not degraded and the vehicle is traveling. The air columnar resonance noise can be greatly reduced.

In the best mode, the height of the spiral continuous irregularities 20 is constant. However, if the height of the irregularities 20 is changed in the circumferential groove 10, the air flow is further increased. Since it is disturbed, the air column resonance noise can be further reduced.
In the above example, the circumferential groove 10 is perpendicular to the tire axis, but it may be a circumferential groove bent in a zigzag shape, and the number of the grooves is not particularly limited.

表１から明らかなように、本発明のタイヤは、騒音レベルが低く、ハイドロプレーニング性能についても、従来と同等であることが確認された。 The tire shown in FIG. 1 in which the circumferential groove is provided with spiral irregularities inclined by 45 degrees with respect to the tire axial direction (Example), and the conventional tire having no irregularities in the circumferential groove (Comparative Example) The air column resonance sound was measured.
The tire size was 195 / 65R15, and each was incorporated into a 6J rim. The tire internal pressure was 220 kPa.
As shown in FIG. 2, the measurement of the air column resonance noise is performed by running the test tire T on the rotating drum 51 with a pressing load of 4.6 kN and a speed of 60 km / hr, and with a tire lateral direction of 2 m and a height of 0. The noise generated by the tire T was detected while the microphone 52 installed at a position of 25 m was moved within a range of 1 m in the front and rear, and the sound pressure average value at 1000 Hz was obtained.
In addition, the hydroplaning performance was evaluated based on the minimum speed at which hydroplaning occurs by causing the test vehicle equipped with each of the tires T to travel at various speeds on the water film 10 mm travel path. The results are shown in Table 1. The evaluation values are values with the conventional example being 100, and the noise level is lower when the number is larger.

As is clear from Table 1, the tire of the present invention has a low noise level, and it has been confirmed that the hydroplaning performance is equivalent to the conventional one.

  Thus, according to the present invention, the air columnar resonance noise during traveling can be significantly reduced without degrading the hydroplaning performance, so the tire noise is reduced while ensuring the safety of the vehicle. be able to.

It is a schematic diagram which shows the detail of the grounding shape and circumferential groove | channel of the pneumatic tire which concerns on the best form of this invention. It is a figure which shows the measuring method of air column resonance sound. It is a schematic diagram which shows the circumferential groove | channel of the pneumatic tire in which the unevenness | corrugation was formed in the conventional circumferential groove | channel. It is a schematic diagram which shows the circumferential groove | channel of the pneumatic tire in which the small recessed part was formed in the conventional circumferential groove | channel.

Explanation of symbols

1 pneumatic tire, 10 circumferential groove, 10a groove wall surface, 10b groove bottom surface,
20 spiral irregularities, 20a convexity, 20b concaveity.

Claims (6)

  A pneumatic tire having a circumferential groove extending along a tire circumferential direction on a tread surface, wherein a spiral continuous unevenness is provided on a groove wall surface and a groove bottom surface of the circumferential groove.   The pneumatic tire according to claim 1, wherein the height of the unevenness is changed in a circumferential groove.   The pneumatic tire according to claim 1 or 2, wherein an angle formed by the spiral irregularities with the tire axial direction is in a range of 30 to 60 degrees.   The pneumatic tire according to any one of claims 1 to 3, wherein a height of the convex portion is 0.2 to 1.0 mm.   The pneumatic tire according to any one of claims 1 to 3, wherein a width of the convex portion is 0.2 to 1.0 mm.   The pneumatic tire according to any one of claims 1 to 3, wherein a width of the recess is 0.2 to 1.0 mm.

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