JP3182184B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of reducing high-frequency noise generated from a circumferential groove at the time of contact with a ground and reducing a feeling of fatigue of a driver.

[0002]

2. Description of the Related Art In recent years, with the speeding up of vehicles, improvement in high-speed running performance is required even for tires. On the other hand, when traveling on a wet road at high speed, the so-called hand-planing phenomenon tends to occur, in which the tires completely float on the water surface and glide, and once hydroplaning occurs, the vehicle becomes uncontrollable. Become.

Therefore, in a conventional tire in consideration of hydroplaning, as shown in FIG. 5, the longitudinal grooves a extending in the circumferential direction have a large cross section so that rain water staying on the tread surface b can be efficiently removed. And it is formed so that it can be discharged reliably.

[0004]

However, when the cross section of the vertical groove is increased, a tunnel-shaped air column space having both ends opened between the tread surface and the road surface is formed between the tread surface and the road surface during traveling. In this case, high-frequency noise of 800 to 1200 Hz is generated in which the air column resonates and emits a sound such as a shear sound or a shoe. Particularly, in recent years where high-speed running is increasing, it is desired to reduce the noise in order to give a driver a feeling of fatigue.

The frequency of such high-frequency noise is related to the circumferential direction of the vertical groove on the ground plane, and its primary resonance frequency can be obtained by the following equation. Resonance frequency (Hz) = (1 / 2L) V where V: sound velocity L: circumferential length of vertical groove on ground contact surface

On the other hand, in a conventional tire, a longitudinal groove having a large groove width is continuously formed in the tire circumferential direction as shown in FIG. 3 in order to prevent generation of a hydroplane .
The occurrence of high frequency noise is inevitable.

In order to eliminate the high frequency noise, it is sufficient to divide the vertical groove. However, by dividing the vertical groove, the drainage property is reduced, so that a hydroplane is easily generated.

[0008] As a result of repeated studies to achieve both reduction of high frequency noise and prevention of hydroplaning, the inventor has found that dislocations formed by partially displacing the longitudinal grooves in the tire direction in the longitudinal grooves. It has been found that by providing a portion and by setting the circumferential length of the dislocation portion in the circumferential direction and the lateral shift amount in a regulated range, it is possible to achieve both reduction of high-frequency noise and suppression of hydroplaning.

It is an object of the present invention to provide a pneumatic tire which can reduce noise particularly in a high frequency range during high-speed running, suppresses the occurrence of hydroplaning, and can run safely.

[0010]

The present invention relates to a pneumatic tire provided with a plurality of longitudinal grooves including a longitudinal groove extending in a circumferential direction at a symmetrical position about a tire equator on a tread surface. Along the symmetrical vertical groove, while providing a plurality of dislocations that are displaced laterally in the tire axial direction, the dislocations ,
A lateral groove and the longitudinal groove extending at one end and the other end from the tread edge.
And the circumferential length of the tire in a normal state where the tire is mounted on a standard rim and a normal internal pressure and a normal load are applied, and the circumferential contact length of the contact surface passes through the tire equator. 0.3 times or more and 0.9 times or less, and the lateral shift amount is 0.4 times or more and 0.8 times or less the groove width of the vertical groove,
In addition, the dislocation portion is a pneumatic tire, wherein at least one end portion of the dislocation portion in the circumferential direction is arranged in a circumferential direction interposed between the rolling contact surfaces.

[0011] The tread surface may be provided with a plurality of lateral grooves passing at least both circumferential ends of the dislocation portion and extending from the tread edge.

[0012]

A plurality of dislocations are provided in the circumferential direction of the tire in such a manner that the longitudinal grooves are shifted laterally in the tire axial direction in the symmetrical longitudinal grooves. As a result, the flutes are continuously connected in the circumferential direction to maintain drainage and suppress the occurrence of hydroplaning, while the air column formed by the flutes and the road surface on the ground contact surface is separated, thereby reducing high-frequency noise. I can do it.

The frequency of the high-frequency noise is related to the circumferential length L of the vertical groove in the ground plane, and its primary resonance frequency (Hz) can be obtained by the following equation. Resonance frequency (Hz) = (1 / 2L) V where V: Sound velocity

In the driver, 800 to 1200
The sound in the frequency range of Hz is an unpleasant sound, and receiving this unpleasant noise causes a feeling of fatigue and hinders long-time driving. Therefore, in order to remove the unpleasant noise, the resonance frequency is shifted to a higher frequency range by shortening the length of the vertical groove forming the length of the air column in the ground contact surface and shifting the vertical groove horizontally. Sound can be removed, and more than half of the noise is absorbed by the groove walls, so that the emission of noise to the outside can be significantly reduced.

The dislocation portion has a length in the circumferential direction of the tire not less than 0.3 times and not more than 0.9 times the contact length of the contact surface. If it is less than 0.3 times, it is described , for example, in [0030].
So that the dislocations are spaced at intervals equal to their circumferential length
In some cases, dislocations and non-dislocations are repeated.
May cause a large number of bends.
At the time, the hydroplaning performance decreases,
When it exceeds 0.9 times, the air column length is almost the same as that of the conventional straight groove, and the noise reduction effect does not appear.

The amount of lateral displacement is set to 0.4 times or more and 0.8 times or less of the width of the vertical groove. If it is less than 0.4 times, the effect of reducing the noise is small, and if it exceeds 0.8 times, drainage becomes poor and hydroplaning performance is reduced.

In addition, since the dislocations are arranged in a circumferential direction with one end thereof interposed in the rolling contact surface, the dislocating portion always has one end in the contacting surface of the rolling tire during running. Therefore, noise during running is continuously reduced.

As described above, according to the present invention, the above-mentioned components are organically combined and integrated, so that the air column which reduces the generation of noise formed by the vertical grooves is divided and the flow of air discharged at the time of grounding is reduced. Can reduce the level of the sound pressure itself of the noise, and disperse the resonance frequency, which can significantly reduce the emission of high frequency unpleasant noise to the outside, and reduce driver fatigue. Become. In addition, since drainage is ensured, the occurrence of hydroplaning is suppressed, and the safety of traveling can be maintained.

When the lateral groove is provided, the circumferential length of the dislocation portion can be set with high accuracy, noise can be more effectively reduced, and drainage can be improved.

[0020]

An embodiment of the present invention will be described below with reference to the drawings. 1 to 3, the pneumatic radial tire 1 is provided with a plurality of longitudinal grooves G including a pair of longitudinal grooves G1, G1 extending circumferentially at a symmetrical position about the tire equator C on the tread surface 2. In this embodiment, a plurality of lateral grooves g extending from the tread edge E are provided. The symmetrical vertical groove G
1, G1 are provided with a plurality of dislocation portions 3... In which the vertical grooves G1, G1 are laterally shifted in the tire axial direction.

The pneumatic tire 1 is located at sidewalls 13, 13 extending inward in the tire equator from both ends of a tread portion 12 forming the tread surface 2, and radially inner ends of the sidewall portions 13. Bead part 14, 14
And a bead core 1 provided in each of the bead portions 14 and 14
A toroidal carcass 16 that passes through the side wall portions 14 and 14 and the tread portion 12 is bridged between the tread portions 5 and 15 and the tread portion 12 and the outer side in the radial direction.
Is provided with a belt layer 17.

The carcass 16 is a so-called radial or semi-radial array in which carcass cords are arranged at an angle of 70 to 90 degrees with respect to the equator C of the tire in this embodiment. , Rayon, aromatic polyamide and the like.

In this embodiment, three belt plies are arranged on the belt layer 17 from the carcass 16 side toward the radial outside of the tire. Further, the belt layer 17 includes belt cords in which the cords of the respective belt plies are arranged inclined with respect to the tire equator C and cross each other. The belt cord is made of nylon, similar to the carcass 16, in addition to steel.
Organic fiber cords such as polyester, rayon, and aromatic polyamide are used.

In the present embodiment, the vertical grooves G are a central vertical groove GO orbiting on the tire equator C, and a pair of symmetrical vertical grooves disposed on both sides of the tire equator C and at symmetrical positions. It consists of grooves G1 and G1. Therefore, on the tread surface 2,
A pair of inner ribs 21 and 21 interposed between the central vertical groove GO and the symmetrical vertical groove G1, and a pair of outer ribs 22 located between the symmetrical vertical groove G1 and the tread edge; 22 are formed.

The horizontal groove g is inclined from one tread edge E to the tire axis and extends to the other edge E while crossing each vertical groove G. Accordingly, the inner rib 21 and the outer rib 22 are formed with inner blocks 21B... Outer blocks 22B arranged in the circumferential direction. In this embodiment, the lateral grooves g are formed over the entire circumference at a pitch P substantially equal in the tire circumferential direction.

In addition, the pneumatic tire 1 has a so-called ground contact surface S which has a certain extent and is in contact with the ground. The contact surface S comes into contact with a road surface in a standard state where the tire is mounted on a standard rim J and a normal internal pressure and a normal load are applied .
Contact width SW in the tire axial direction of the contact surface S
Is set in the range of 0.5 to 1.0 times the tread width TW, which is usually the distance between the tread edges, and the circumferential length SL of the ground contact surface S on the tire equator C is 0% of the tread width. .6
It is set to a range of up to 1.0 times.

The symmetrical vertical grooves G1 and G1 respectively pass through the area of the ground plane S, and in the present embodiment, the area of the ground plane S also at the intersection A where the horizontal groove g intersects the symmetrical vertical groove G1. Located within.

The dislocations 3 provided in the symmetrical vertical groove G1 are:
The intersection A1 separating from intersection point A of the intersection A between the longitudinal grooves G1 and lateral grooves g of the symmetric part twice the distance 2P pitch P of lateral grooves g in the circumferential direction and the other end, thus, the dislocations 3
Has one end and the other end with a lateral groove g extending from the tread edge.
It is located at intersections P, P1 with the vertical grooves G1, G1. Again
The dislocation portion 3 includes a symmetrical vertical groove G between the intersection A and the intersection A1.
1, the position is shifted in the tire axial direction. to this
Therefore, in the dislocation portion 3, one symmetrical vertical groove G1 (FIG. 1)
In the right) is shifted to the tire equator C side,
The other symmetrical vertical groove G2 (left side in FIG. 1) is displaced toward the tread end E at a position substantially opposed to the vertical groove G2 .

The dislocation portion 3 has a circumferential length L, that is, a distance between the intersection points A and A1 in this example, which is 0.3 times or more and 0.9 times the circumferential contact length L of the contact surface S. On the other hand, the lateral displacement amount l is set to be 0.4 times or more and 0.9 times or less the groove width WG of the symmetrical vertical groove G1.

The dislocation 3 has a circumferential length L
A plurality of the dislocation portions 3 are arranged in the circumferential direction so that at least one end of the dislocation portion in the circumferential direction is interposed on the rolling contact surface to be rolled. .

FIG . 4 is a reference diagram of the tread pattern.
In this reference drawing, the horizontal groove g is defined by a vertical groove G
1 is formed as a rib block pattern provided only on the outer ribs 22 and one end and the other end of the dislocation portion 3 are provided in the symmetrical vertical groove G1 at a position different from the intersection with the horizontal groove g. ing. The dislocation portion 3 is connected at one end and the other end thereof to the main body of the vertical groove G1 by connecting grooves 5 and 5 having a small length.

In the pneumatic tire of the present invention, the symmetrical vertical grooves may extend in the circumferential direction of the tire and have a gentle wavy shape with a small wave height, or a rib-lug pattern having lugs instead of lateral grooves. The present invention can be modified into various aspects.

[0033]

[Specific Example] A tire (example) having a tire size of 165 / 70R13 and having the configuration shown in FIGS. 1 and 2 was prototyped, and the tire was mounted on all wheels of a test vehicle, and a noise test was performed by running on a road. The performance was investigated. For comparison, a tire (comparative example) having the same configuration as that of the example and having the tread pattern shown in FIG. 5 and a conventional configuration (comparative example) was also tested and its performance was tested.

The noise was measured as follows. JA
The test was carried out according to the actual vehicle coasting test method specified in SOC 606. The actual vehicle equipped with the test tires was coasted on a linear test course at a constant speed for a distance of 50 m, and at the middle point of the course, 7 km laterally from the traveling center line. The passing noise was measured by a stationary microphone placed at a height of 1.2 m from the test road surface at a distance of 0.5 m, and the noise was subjected to frequency analysis, which was shown in dB (A). At the time of the test, the passing speed was 80 km / H.

The test results are shown in the graph of FIG. In the figure, the broken line indicates the example and the solid line indicates the comparative example.

As a result of the test, it was confirmed that the noise in the high frequency range of 800 Hz or more was significantly reduced in the example of the present invention as compared with the comparative example.

[0037]

As described above, the pneumatic tire of the present invention is provided with a plurality of dislocations laterally displaced in the tire axial direction in symmetrical vertical grooves arranged on the tread surface, and also in the circumferential direction of the tread surface. Because the gist is to regulate the ratio of the circumferential length to the length and the amount of lateral displacement with respect to the groove width of the vertical groove, noise reduction during traveling while maintaining drainage and suppressing the occurrence of hydroplaning, In particular, high-frequency noise of 800 Hz or more can be reduced, discomfort and fatigue of the driver can be eliminated, and the driving environment can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing a tread pattern according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view in the tire axial direction.

FIG. 3 is a graph showing a result of frequency analysis of noise.

FIG. 4 is a plan view showing a reference example of a tread pattern .

FIG. 5 is a plan view showing a tread pattern according to the related art.

[Explanation of symbols]

 2 Tread surface 3 Dislocation part C Tire equator E Tread edge G Vertical groove G1 Symmetrical vertical groove g Horizontal groove J Rim L Circumferential length l Lateral shift amount S Ground plane SL Circumferential ground length WG Groove width

Claims (2)

(57) [Claims] 1. A pneumatic tire provided with a plurality of longitudinal grooves including a longitudinal groove extending in a circumferential direction at a symmetrical position about a tire equator on a tread surface, wherein the symmetrical longitudinal groove has A plurality of dislocation portions are provided in which the grooves are laterally displaced in the tire axial direction, and the dislocation portions have one end and the other end extending from a tread edge.
It is located at the intersection of the horizontal groove and the vertical groove, and its circumferential length passes through the tire equator on the ground contact surface in a normal state where the tire is mounted on a standard rim and a normal internal pressure and a normal load are applied. 0.3 to 0.9 times the circumferential contact length, and the lateral displacement is 0.4 times or more and 0.1 times the width of the vertical groove.
A pneumatic tire characterized in that the dislocations are eight times or less, and that the dislocations are arranged in a circumferential direction in which at least one end of the dislocations in the circumferential direction is interposed on the rolling contact surface. 2. The pneumatic tire according to claim 1, wherein the tread surface includes a plurality of lateral grooves passing at least both circumferential ends of the dislocation portion and extending from a tread edge.