JPH071912A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a pneumatic tire to suppress the noise generated by vibrating a side wall part from a tread part by changing the number of the strand of the ply cord of at least one carcass ply of a radial carcass in the circumferential direction of the tire. CONSTITUTION:An inner reinforcing structure of a tire consists of a radial carcass 6 formed by two carcass plies 4, 5 consisting of ply cords 4a, 5a extending at an angle of approximately 90 deg. relative to the circumferential direction of the tire and two steel belt layers 7a, 7b arranged on the outer circumferential side of this crown part, and is provided with a belt where the cords cross each other between each layer and a belt reinforcing layer 8 consisting of an organic fiber cord on the outer circumferential side. The number of strand of the ply cord 5a constituting the carcass ply 5 on the outer layer side is only changed regularly or irregularly in the circumferential direction of the tire. The vibrating condition of the side wall part is changed in the circumferential direction according to the change of the number of strand of the ply cord.

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 an improvement in carcass structure, and particularly to a noise generated by a tire without impairing the dynamic performance of the tire and the riding comfort of a vehicle. Is effectively reduced.

[0002]

2. Description of the Related Art With the recent development of road networks and higher performance of vehicles, demands for performance improvement of pneumatic tires are increasing, and reduction of noise generated from tires is one of them. Therefore, conventionally, focusing on the tread portion that is in direct contact with the road surface, by setting the pitch of the tread pattern to an unequal pitch, the noise generated when the trend portion collides with the road surface is reduced to white noise, and Prevents the frequency from protruding, and softens the tread rubber and optimizes the angle for impact input to mitigate the collision impact itself that is input from the road surface to the tread portion, and the impact impact is applied to the tread portion and sidewall portion. It was common to take noise countermeasures, such as by reducing the noise generated by vibrating.

[0003]

By the way, since the tread portion of the tire is the portion that directly affects the most important movement performance of the tire, there is a limit to the conventional noise countermeasures. The demand for even lower noise cannot be fully satisfied.

The present invention pays particular attention to the sidewall portion of the tire, and suppresses the noise generated by the impact shock input to the tire from the tread portion causing the sidewall portion to vibrate, and the total amount of the generated noise is reduced. It is intended to provide a pneumatic tire that effectively reduces noise and effectively reduces noise.

[0005]

A pneumatic tire of the present invention comprises a tread portion, a sidewall portion and a bead portion, and a radial carcass consisting of at least one carcass ply, and an outer periphery of a crown portion of the radial carcass. With a belt arranged on the side, sometimes,
A tire that may include a belt reinforcing layer disposed further on the outer peripheral side of the belt, wherein the radial carcass comprises:
In at least one carcass ply, the twist number of the ply cord is changed in the tire circumferential direction, for example, regularly or irregularly.

[0006]

As described above, the noise generated by the pneumatic tire naturally includes the noise generated by the vibration of the sidewall portion due to the input of the road surface collision impact on the tread portion. By the way, in the pneumatic tire of the present invention, the twist number of the ply cord is changed in the tire circumferential direction,
Since the rigidity of the sidewall portion is changed in the circumferential direction, the vibration state of the sidewall portion differs depending on the circumferential position, and the vibration of the sidewall portion can be effectively transmitted in the tire circumferential direction. Since the vibrations are blocked and become non-uniform and discontinuous in the circumferential direction, the noise generated due to the vibrations of the sidewall part is not generated in the frequency band as in the pitch variation of the tread part. It can be effectively reduced by dispersion and buffering of vibration transmission.

In order to make the above-mentioned point sufficiently effective, it is preferable to change the twist number of the ply cord within a length shorter than the ground contact length of the tire. In this case, the twist number changes. It is preferable that the degree is such that unevenness does not occur in the sidewall portion due to the difference in the amount of cord shrinkage during vulcanization molding of the tire.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional perspective view showing an embodiment of the present invention with a portion broken and removed, in which 1 is a tread portion and 2 is a
A pair of sidewall portions continuous with the tread portion 1,
Reference numeral 3 denotes a bead portion connected to each sidewall portion 2.

The internal reinforcing structure of the tire here is as follows:
A radial carcass 6 formed by two carcass plies 4 and 5 consisting of ply cords 4a and 5a extending at an angle of approximately 90 degrees with respect to the tire circumferential direction, and a radial carcass 6 arranged on the outer peripheral side of the crown portion of the radial carcass 6. A belt 7 composed of two layers of steel belt layers 7a, 7b provided, wherein cords intersect each other between the layers, and an organic fiber cord extending substantially in the tire circumferential direction further on the outer peripheral side of the belt 7. The belt reinforcing layer 8 is formed.

In this example, among the ply cords 4a and 5a made of 1500d / 2 polyester cords, only the number of twists of the ply cords 5a constituting the carcass ply 5 on the outer layer side is, for example, in the tire circumferential direction, , Up to 40 times / 10 cm
To a minimum of 25 twists / 10 cm, the number of twists varies, either regularly or irregularly.

FIG. 2 is a partially developed view of the carcass ply 5 exaggeratingly showing this.
The twist number of the ply cord 5a is sequentially changed in the tire circumferential direction at intervals of 5 cm to 25 times / 10 cm, 40 times / 10 cm, and 34 times / 10 cm. In addition, here, it is supposed that only the twist number of the ply cord 5a is changed in the tire circumferential direction,
In addition to or instead of this, the twist number of the ply cord 4a can be changed.

According to the tire constructed as described above, as described above, the vibration state of the sidewall portion 2 caused by the tread portion 1 colliding with the road surface is
It changes in the tire circumferential direction as the number of twists of the ply cord 5a changes.
Of the vibration of the tire in the circumferential direction of the tire is effectively blocked by the change of the natural frequency of each part of the sidewall portion due to the change of the twist number. As a result, the total amount of generated noise is Will be greatly reduced compared to

[Comparative Example] A comparative test regarding noise generated between the inventive tire and the conventional tire will be described below. ◎ Test tire size 205/60 R15 tire with carcass
Made of one carcass ply of 1500d / 2 polyester cord, the belt is made of two belt layers of steel cord extending at an angle of 22 degrees to the tire circumference, and the belt Reinforcement layer made of 1260d / 2 nylon cord.・ Invention tire Carcass ply cord twists 40 times / 10 cm, 34 times / 10
cm and 25 times / 10 cm, 3 types, 5 cm in the tire circumferential direction
Tires that repeat these alternately for each.・ Conventional tire A tire in which the number of twists of the carcass ply cord is 40 times / 10 cm over the entire circumference of the tire. ◎ Test method According to JASO C606, the passing noise during running at 50 km / h was measured and evaluated. ◎ Test result As a result of the above test, the passing noise of the conventional tire is 75.2 dB (A)
On the other hand, that of the invention tire was 73.4 dB (A). It was confirmed that the tires of the invention and the conventional tires were almost the same in terms of driving performance such as steering stability and riding comfort.

[0014]

As is apparent from the above comparative examples, according to the present invention, in particular, by changing the twist number of the carcass ply cord in the tire circumferential direction, the tire performance, the ride comfort on the vehicle, etc. It is possible to effectively reduce the noise generated by the tire without damaging the tire.

[Brief description of drawings]

FIG. 1 is a sectional perspective view showing an embodiment of the present invention.

FIG. 2 is a partial development view of an outer layer side carcass ply.

[Explanation of symbols]

 1 tread part 2 sidewall part 3 bead part 4, 5 carcass ply 4a, 5a ply cord 6 radial carcass 7 belt 7a, 7b belt layer 8 belt reinforcement layer

Claims (1)

[Claims] 1. A carcass formed of at least one carcass ply comprising a tread part, a pair of sidewall parts and a bead part, and a ply cord extending at an angle of approximately 90 degrees with respect to the tire circumferential direction. A pneumatic tire comprising a belt layer of at least two layers arranged on the outer peripheral side of the crown portion of the carcass, the belt having cords intersecting each other between the layers, the carcass of at least one sheet In a carcass ply, a pneumatic tire in which the twist number of ply cords is changed in the tire circumferential direction.