JP3308334B2 - Automotive pneumatic tires - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire for automobiles, and more particularly to a pneumatic radial tire for passenger cars with reduced noise, that is, white noise.

[0002]

2. Description of the Related Art With the maturation of the car life scene, automobiles are now required to be more quiet and comfortable.
Above all, quietness that can distinguish the subtle sounds of audio systems is currently strongly demanded by high-performance vehicles around the world. There are three main types of cabin noise. That is, the sound of the engine, the sound of the body cutting the wind, and the tire noise. Relative tire noise stands out in Japan, where cruising in the speed range of around 100 km / h and the engine speed is around 2500-3000 rpm is predominant.

[0003] In recent years, tire noise has recently been reduced.
It has become a major theme not only in luxury saloons but also in sports cars. About engine sound,
It has been suppressed by improving accuracy, while the wind noise of the body has been gradually reduced due to the evolution of aerodynamic design. In other words, it can be said that tires are the key to lower noise in cars from now on. The key to silencing this low noise is how to suppress the physical and primitive phenomena of hitting the road surface with the tire tread rotating at high speed and resonating with the air.

In order to suppress noise, it is effective to reduce the width of the main groove and to keep the main groove away from the tire center portion to the shoulder portion.
Hydroplaning resistance is impaired. From such a viewpoint, a radial tire provided with a tread having a rib / block pattern shown in FIG. 2 has been proposed.

[0005]

In the radial tire shown in FIG. 2, side blocks 5 having a sub-groove 4 are arranged in the circumferential direction on both sides of a center rib 2 having a sub-groove 1 via a main groove 3. , Shoulder blocks 7 are arranged in the circumferential direction via the main groove 6, and each block 5, 7 is a rib / block pattern in which the length in the circumferential direction is independently changed.
The noise is reduced by shifting the source generated by hitting or hitting the air column resonance in the straight main grooves 3, 6 by the block edge in the circumferential direction. In the rib block pattern, the tire
A pattern of a predetermined length in the circumferential direction is called a “basic pattern”,
This basic pattern is continuously arranged to form one circumference of the tire
Is done. The circumferential length of this basic pattern is called "pitch".
Say. The ones with this pitch changed are called "Pitch Varie
Solution ". In other words, the pitch of the basic pattern
If L, Lm shorter than L and Ln longer than L are run.
The rib / block pattern around the tire is arranged along the dam.
Is done. This basic pattern includes horizontal grooves.
The groove width is G. The width of this lateral groove is also pitch
Has been changed accordingly.

However, in this conventional technique, noise must be reduced only by a change in pitch variation, and when the pitch is increased, the stability and the like are deteriorated, so that there is a limit to noise reduction. Thus, the present invention randomly changes the length of each pitch of the block in the circumferential direction and changes the groove width of the lateral groove differently from the block pitch, without impairing wet performance and operability. It is an object of the present invention to provide a pneumatic tire for automobiles that ensures noise performance.

[0007]

In order to achieve the above object, the present invention takes the following measures. That is, the feature of the present invention is that a plurality of circumferential land portions are defined by a plurality of vertical grooves extending in the circumferential direction, and the circumferential land portions are circumferentially defined by a plurality of lateral grooves. In an automobile pneumatic tire having a tread in which circumferential blocks are formed and the blocks are circumferentially arranged according to a basic pattern, a plurality of circumferential lengths of the basic pattern are set, and the plurality of types are set. Are randomly arranged in the circumferential direction, a plurality of types of groove widths of the lateral grooves are set, and the plurality of types of lateral grooves are arranged in a random arrangement different from the random arrangement of the basic pattern.

[0008] The circumferential blocks are left and right side blocks.
Should be left and right shoulder blocks
Is done.

[0009]

When the tire according to the present invention is mounted on an automobile and running, noise generated by the excitation of the half-wavelength column resonance in the vertical groove by the block edge is generated in the shoulder block in the low-speed region. The low frequency generates a high frequency in a high speed region in a side block or the like, and the lateral groove position becomes an appropriate position, thereby dispersing the frequency of each other's noise and generating white noise.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIGS. 1A and 1B, a tire for automobiles, specifically a radial pneumatic tire T for a passenger car, etc. It is provided with a bead portion 10 and a sidewall portion 11, and both sidewall portions 11 are so-called tubeless having a toroidal cross section by being coupled to a tread portion 13 via a shoulder portion 12. A plurality of treads (parts) 13 extend in the circumferential direction, in this embodiment, a straight center rib 14 located on the equatorial plane, straight side longitudinal grooves 15 formed at symmetrical positions, and left and right of the center rib 14. A plurality of circumferential land portions are formed by forming straight shoulder vertical grooves 16 formed at symmetrical positions and at positions outside the side vertical grooves 15, a center land portion by the center rib 14 in the embodiment, a pair of side land portions. The shoulder land portions are defined and arranged, and a pair of side land portions and shoulder land portions of the circumferential land portions are circumferentially partitioned by lateral grooves 17 to form side blocks 19 and shoulder blocks 20 and arranged. are doing. The side land portions of the pair are narrow and are partitioned in the width direction by side straight vertical sub-grooves 18.

The tread pattern is formed by the side block.
The present embodiment the length of each pitch in 19 and the circumferential direction of the shoulder block 20 are set to three types L1, L2, L3
You. That is, at a predetermined length in the tire circumferential direction,
A group of blocks placed in the block
And this predetermined length in the circumferential direction is called "pitch".
However, three types of pitches, L1, L2 and L3, are provided and randomly arranged.
It is location. The basic pattern includes a lateral groove 17,
The groove width is G. And the groove width of the lateral groove 17
Gx is set in plural types, and the plural types of lateral grooves 17 are
The array is different from the random array of the basic pattern.
You. The plurality of types of groove widths Gx are the groove widths of the basic pattern.
G is set in the range of Gx = 0.8 G to 1.2 G.

Here, Gx = 0.8G to 1.2G is set for the following reason. If it is 1.2 G or more, the width of the lateral groove becomes too wide, and the steering performance is reduced. On the other hand, if it is 0.8 G or less, the width of the lateral groove becomes too narrow, and the wet performance is reduced. Here, in the present invention, various variations are possible by changing the length of each pitch of the block in the circumferential direction, and by setting Gx = 0.8G to 1.2G, the frequency of each noise is dispersed, A noise reduction system that converts to white noise is configured.

Although one pitch length is three types in the embodiment, it can be made up to five types, and the random arrangement of the lateral groove width can be freely changed within the above range.
Further, in the illustrated example, the shoulder block 20 has a so-called hawk-wing shape, and the side blocks 19 have a rhombic shape whose phases are shifted in the circumferential direction and have different directions, but the shapes of these blocks are arbitrary. is there. Further, as shown, it is also possible to freely form a sipe 21 in each of the blocks 19 and 20.

Next, the test results are shown in Table 1 below. table
As is clear from FIG. 1, in the circumferential direction of the blocks 19 and 20,
Lengths L1, L2, L3 for each pitch at random
According to the present invention which is arranged and changes the groove width Gx of the lateral groove 17 in the range of Gx = 0.8 G to 1.2 G , the noise performance,
We are satisfied with wet performance and maneuverability
However, when Gx is 0.79G or less, wet performance is sacrificed.
When Gx is 1.21G or more, noise
Noh and maneuverability are sacrificed.

[0015]

[Table 1]

It should be noted that the above illustrated example is one embodiment of the present invention.
It may be a so-called zigzag shape or a combination of a straight shape and a zigzag shape. In addition, the lateral groove can be formed in a so-called V-shape as shown in FIG. 2, whereby the wet performance can be improved.

[0017]

As described above, the present invention has various variations in the tread block pattern, so that the noise frequency can be dispersed and white noise can be obtained, and the wet performance and the controllability are impaired. Nothing.

[Brief description of the drawings]

1A and 1B show an embodiment of the present invention, wherein FIG. 1A is a developed plan view of a main part, and FIG. 1B is a sectional view.

FIG. 2 is a developed plan view of a main part of a conventional example.

[Explanation of symbols]

 T Tire 13 Tread 15 Vertical groove 16 Vertical groove 17 Horizontal groove 19 Side block 20 Shoulder block One pitch length of L1 block One pitch length of L2 block One pitch length of L3 block Gx Horizontal groove width

Claims (2)

(57) [Claims] 1. A plurality of longitudinal grooves (15), (16) extending in a circumferential direction.
Forming a plurality of circumferential land portions, and forming the circumferential land portions in a circumferential direction by a plurality of lateral grooves (17) to form circumferential blocks (19) and (20); and In a pneumatic tire for automobiles (T) provided with a tread (13) in which blocks are circumferentially arranged according to a basic pattern, a plurality of types (L1, L2, L3) of circumferential lengths of the basic pattern are provided.
The plurality of types (L1, L2, L3) are randomly arranged in the circumferential direction, and a plurality of types of groove widths (Gx) of the lateral grooves (17) are set. 17), automobile pneumatic tire characterized by that a different random sequence a random sequence of the basic pattern. 2. The peripheral blocks (19) and (20) are left and right.
Side blocks (19) and left and right shoulder blocks
The pneumatic tire for automobiles according to claim 1 , wherein (20) .