JP3397374B2 - Pneumatic tire - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to an improvement of a carcass structure. This effectively reduces the noise generated by the tire without damaging the tire. 2. Description of the Related Art With the recent improvement 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. ing. Therefore, conventionally, attention is paid to the tread portion directly in contact with the road surface, and the pitch of the tread pattern is made to be unequal pitch, so that the noise generated by the tread portion colliding with the road surface is converted to white noise and a specific frequency is obtained. Prevent it from protruding, and
The softening of the tread rubber and the optimization of the angle with respect to the impact input alleviate the collision impact itself input from the road surface to the tread, and the collision impact is generated by exciting the tread and sidewalls It was common to take noise countermeasures, such as by reducing noise. [0003] Since the tread portion of the tire is a portion that directly affects the most important athletic performance of the tire, conventional noise countermeasures have their own limits. However, recent demands for further noise reduction cannot be sufficiently satisfied. The present invention pays particular attention to the sidewall portion of the tire, and suppresses the noise generated by the collision impact input to the tire from the tread portion vibrating the sidewall portion, thereby reducing the total amount of generated noise. The present invention provides a pneumatic tire that effectively reduces noise and thereby effectively reduces noise. [0005] A pneumatic tire according to the present invention has a tread portion, a sidewall portion and a bead portion, a radial carcass comprising at least one carcass ply, and a crown of the radial carcass. With a belt arranged on the outer periphery of the part,
A tire that may include a belt reinforcing layer disposed on the outer peripheral side of the belt, wherein the radial carcass
In at least one carcass ply, the driving density of the ply cord is changed in the tire circumferential direction, for example, regularly or irregularly. The noise generated by the pneumatic tire naturally includes the noise generated due to the vibration of the sidewall portion due to the input of the road impact to the tread portion, as described above. By the way, in the pneumatic tire of the present invention, since the driving density of the ply cord is changed in the circumferential direction of the tire to change the rigidity of the sidewall in the circumferential direction, the vibration state of the sidewall is changed in the circumferential direction. In addition to being different depending on the position, the transmission of the vibration of the sidewall portion in the circumferential direction of the tire is effectively prevented, and the vibration becomes non-uniform and discontinuous in the circumferential direction. The noise generated due to the vibration of the part is effectively reduced due to the dispersion of the frequency band and the interference of the vibration transmission as in the pitch variation of the tread part. [0007] In order to make the above effect sufficiently effective, it is preferable to change the driving density within a length shorter than the contact length of the tire. Is preferably performed within a range that does not cause unevenness on the outer surface of the sidewall portion. An embodiment 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 by partially removing and removing the same. In FIG.
A pair of sidewall portions continuous with the tread portion 1,
Reference numeral 3 denotes a bead portion connected to each side wall portion 2. Here, the internal reinforcing structure of the tire is as follows.
A radial carcass 6 formed by two carcass plies 4, 5 composed of ply cords 4 a, 5 a extending at an angle of substantially 90 degrees with respect to the tire circumferential direction, and a radial carcass 6 is arranged on the outer peripheral side of a crown portion. A belt 7 comprising two steel belt layers 7a and 7b provided with cords intersecting each other between the layers, and an organic fiber cord extending substantially in the tire circumferential direction on the outer peripheral side of the belt 7 further. And a belt reinforcing layer 8. In this example, among the ply cords 4a and 5a made of 1500d / 2 polyester cord, only the driving density of the ply cord 5a constituting the carcass ply 5 on the outer layer side is determined in the tire circumferential direction, for example. The density is varied regularly or irregularly from a maximum of 45 lines / 5 cm to a minimum of 36 lines / 5 cm. FIG. 2 is a partially expanded view of the carcass ply 5 exaggerating this point.
The density of the ply cord 5a is set at 36/5 for every 5 cm.
cm, 45 / 5cm, and 40 / 5cm. Note that, here, only the driving density of the ply cord 5a is changed in the circumferential direction, but it is also possible to change the driving density of the ply cord 4a in addition to or instead of this. According to the tire configured 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,
The driving density of the ply cord 5a changes in the circumferential direction of the tire with the change of the driving density, and the transmission of the vibration of the sidewall portion 2 in the circumferential direction of the tire is caused by the change of the driving density. It is effectively prevented by the change of the natural frequency of each part, and as a result,
The total amount of generated noise is greatly reduced as compared with the prior art. [Comparative Example] A comparative test on the generated noise between the inventive tire and the conventional tire will be described below. ◎ The test tire size is 205/60 R15 and the carcass
The belt is formed of a single carcass ply of 1500d / 2 polyester cord, the belt is formed of two belt layers of steel cord extending at an angle of 22 degrees to the tire circumferential direction, and The reinforcing layer is made of 1260d / 2 nylon cord. A tire in which the driving density of the inventive tire carcass ply cord is set to three types of 45 / 5cm, 40 / 5cm and 36 / 5cm, and these are alternately repeated every 5cm. -A tire in which the driving density of the conventional tire carcass ply cord is 45 / 5cm over the entire circumference of the tire. ◎ The passing noise during running at 50 km / h was measured and evaluated in accordance with the test method JASO C606. ◎ Test result As a result of the above test, the passing noise of the conventional tire was 75.2 dB (A)
On the other hand, that of the inventive tire was 73.1 dB (A). In addition, it was confirmed that the tires of the present invention and the conventional tires had almost the same exercise performance such as steering stability performance and riding comfort. As is clear from the above comparative example, according to the present invention, particularly, by changing the driving density of the carcass ply cord in the circumferential direction of the tire, the exercise performance of the tire and the vehicle performance can be improved. The noise generated by the tires can be effectively reduced without impairing the riding comfort of the vehicle.

[Brief description of the 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 section 2 Side wall 3 Bead part 4,5 carcass ply 4a, 5a ply cord 6 radial carcass 7 belt 7a, 7b Belt layer 8 Belt reinforcement layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60C 9/02 B60C 9/04 B60C 9/08

Claims (1)

(1) A carcass comprising a tread portion, a pair of sidewall portions and a bead portion, and a ply cord extending at an angle of substantially 90 degrees with respect to a tire circumferential direction. A pneumatic tire comprising a carcass formed of at least one ply and at least two belt layers disposed on an outer peripheral side of a crown portion of the carcass, and a belt in which cords cross each other between the layers. A pneumatic tire in which at least one carcass ply of the carcass has a driving density of a ply cord changed in a tire circumferential direction.