JPH08108704A - Pneumatic tire - Google Patents

Abstract

PURPOSE: To reduce an external noise while steering stability and riding comfort being maintained. CONSTITUTION: A carcass 10 is formed out of an inner carcass ply 11 running from a tread section and bent around the bead core of a bead section via a side wall, and an outer carcass ply 12 running from the tread section along the outside of the inner carcass ply 11 and extending at least to the vicinity of the bead core via the side wall. In addition, a ratio of a count E1 per unit length of a carcass cord 13 in the inner carcass ply 11 to a count E2 per unit length of a carcass cord 14 in the outer carcass ply 12 is taken at a value between 0.5 and 0.96, or between 1.04 and 1.50.

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 the noise outside the vehicle and the noise inside the vehicle while maintaining steering stability and riding comfort.

[0002]

2. Description of the Related Art In recent years, there has been a demand for reducing outside (passing) noise generated from tires during running, and regulations are becoming stricter legally.

Conventionally, in order to reduce the noise generated from a tire, in a carcass, a material having low rigidity is used for a carcass cord constituting the carcass, or the number of driving per unit length is reduced to reduce the tire. By lowering the rigidity, the occurrence of sound vibration was suppressed. The reason is that if the tire rigidity is low, the input from the road surface can be alleviated, and the vibration of the tread portion itself on the road surface becomes small.

[0004]

However, when a cord having low rigidity is used, or when the number of driving is simply reduced,
As described above, the reduction in tire rigidity causes a problem that steering stability is reduced although noise is reduced. As described above, there is a trade-off relationship between suppression of noise outside the vehicle and noise inside the vehicle and ensuring of steering stability.

The inventor has conducted research in order to achieve both suppression of vehicle exterior noise and vehicle interior noise and securing of steering stability and riding comfort.
As a result of repeated experiments, a carcass is formed by two carcass plies. The number of driving carcass cords is different between one ply and the other ply of the two carcass plies. Furthermore, by controlling the relative ratio of the driving numbers of both carcass cords, there is a range in which vehicle exterior noise and vehicle interior noise can be reduced without impairing steering stability and riding comfort. Was found.

According to the present invention, the carcass is formed by two carcass plies, the inner and outer carcass plies, and the number of driving carcass cords used for the inner and outer carcass plies is different. At the same time, the object is to provide a pneumatic radial tire capable of reducing the noise outside the vehicle and the noise inside the vehicle.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to an inner carcass ply in which carcass cords are arranged in parallel and folded back around a bead core of a bead portion from a tread portion to a sidewall portion, and an outer side in a radial direction of the inner carcass ply. A pneumatic tire comprising a carcass consisting of an outer carcass ply in which carcass cords are arranged in parallel with each other while extending at least in the vicinity of the bead core from the tread part through the sidewall part, and at a right angle to the carcass cord of the inner carcass ply. The ratio E1 / E2 of the number E1 of driving carcass cords per unit length in the direction of and the number E2 of driving carcass cords per unit length in the direction perpendicular to the outside carcass cord is 0.5 or more. And 0.96 or less, or 1.
It is a pneumatic tire characterized by being 04 or more and 1.50 or less.

The carcass cord of the inner carcass ply and the carcass cord of the outer carcass ply are preferably made of the same material and have substantially the same thickness.

The inner and outer carcass plies may have a so-called 1-1 structure in which the outer carcass ply passes through the outside of the bead core in the axial direction of the tire as shown in FIG. 1, and as shown in FIG. The outer carcass ply may have a so-called 2-0 structure in which the bead core is wound in the same direction as the inner carcass ply.

Further, the inner and outer carcass plies can be formed as a so-called low turn-up whose winding end ends inside in the tire radial direction with respect to the tip of the rim flange, and also ends outside in the tire radial direction with respect to the tip of the bead apex. It may be formed as a so-called high turn-up.

[0011]

In the inner and outer carcass plies, the carcass cord driving numbers E1 and E2 per unit length of the respective carcass cords forming the ply differ, and the ratio E1 / E2 is set to 0.
It is set to 5 or more and 0.96 or less, or 1.04 or more and 1.50 or less. The ratio E1 / E2 is less than 0.5 or 1.
When it exceeds 50, the steering stability is lowered, and the noise outside the vehicle is moderated as shown in FIG. 4, resulting in little effect. Further, when the ratio E1 / E2 exceeds 0.96 and is less than 1.04, that is, when the carcass cords of the inner and outer carcass plies are substantially the same as in the conventional product, the generation of noise outside the vehicle is suppressed. The effect is poor.

Thus, in order to achieve both steering stability and noise suppression, the ratio E1 / E2 must be restricted within a limited range.

When the number of driven carcass cords in either the inner or outer carcass ply is set to 50 or more per 50 mm, the steering stability is further improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 3, the pneumatic tire 1 includes a carcass 10 formed by an inner carcass ply 11 and an outer carcass ply 12.

The inner carcass ply 11 has a tread portion 2
Through the sidewall portion 3 and along the inner surface of the triangular bead apex 8 in the tire axial direction, and folds around the bead core 5 of the bead portion 4 from the inner side to the outer side in the tire axial direction. In the present embodiment, the tip end 11a rises outside the outer edge of the rim 8 and is located inward of the outer edge P of the flange of the regular rim J to which the bead portion 4 is fitted in the tire radial direction.

The outer carcass ply 12 is arranged outside the inner carcass ply 11 and hangs from the tread portion 2 through the sidewall portion 3 along the outer surface of the bead apex 8 and at the same time as the bead core of the bead portion 4. 5
It terminates in the vicinity and between the bead core 5 and the folded portion of the carcass ply 11 inside. Therefore, the carcass 10 in this embodiment is formed as a so-called 1-1 LTU structure.

The inner carcass ply 11 and the outer carcass ply 12 are both carcass cords 13 and 14 made of organic fibers such as nylon, polyester, rayon, and aromatic polyamide fibers, in this example, 70 to 90 with respect to the tire equator C. A sheet body is formed by covering a comb-shaped fabric inclined with an angle of degrees with a topping rubber 15. Between the inner and outer carcass plies 11 and 12, the carcass cords 13 and 14 are arranged so as to intersect with each other.

The carcass cords 13 and 14 have a denier number of 1500d / 2 or less and 600d or less, which is their thickness.
/ 2 or more, and in this embodiment, between the inner and outer carcass plies 11 and 12, the respective carcass cords 1
The cords 3 and 14 are made of the same material and have the same denier number.

The carcass 10 is 50 mm in a direction perpendicular to the carcass cord 13 in the inner carcass ply 11.
Hitting number E1 of the carcass cord per hit and 5 in the direction perpendicular to the carcass cord 14 of the outer carcass ply 12
As shown in FIG. 2, the ratio of the carcass cord driving number E2 per 0 mm is set to 0.5 or more and 0.96 or less.

Further, as shown in FIG. 3, E1 / E2 which is the ratio of the number of driving may be 1.04 or more and 1.50 or less. In this way, the carcass 10 is different between the inner and outer carcass plies 11 and 12 so that the driving numbers E1 and E2 of the carcass cords do not become the same, and the carcass plies 11 and 12 do not have an extreme difference. is there.

In the tread portion 2, the carcass 1
The belt layer 1 on the outer side in the radial direction of 0 and inside the tread portion 2.
7 will be placed. In the present embodiment, the belt layer 17 is composed of two belt plies in which belt cords made of organic fiber cords such as nylon, rayon, polyester, aromatic polyamide or steel cords or steel cords are inclined with respect to the tire equator C and arranged in parallel. The tread portions 2 are formed by arranging the belt cords so as to intersect with each other, exhibiting a hoop effect, and overlapping the belt cords to enhance the rigidity of the tread portion 2.

Further, the tread portion 2 is provided with a band layer 19 made of a ply in which band cords are embedded on the outer side in the radial direction of the belt layer 17 to prevent lifting of the belt layer 17 due to centrifugal force during tire running. There is.

In the present embodiment, in the bead portion 4, the bead apex 8 made of hard rubber rises from the bead core 5 outward in the radial direction of the tire, and the chafer 21 and the filler 22 for reinforcing the bead portion 4. And with.

The chafer 21 is made of synthetic or natural fibers and formed into a net. In this example, one end is attached to the outer surface of the outer carcass ply 12 on the outer side of the bead portion 4 in the tire axial direction, and It extends inward in the tire axial direction along the bottom surface 4a and rises along the inner wall surface of the bead portion 4.

The filler 22 is made of synthetic or natural fibers and is arranged between the carcass ply 11 and the bead core 5 so as to surround the bead core 5.

Such chafer 21 and filler 22
By interposing the above, it helps to increase the rigidity of the bead portion 4 in the vertical and horizontal directions. The bead portion may be formed without providing a chafer or filler.

FIG. 5 shows another mode of the carcass. In this example, the outer carcass ply 12A extends to the bead core 5 from the tread portion 2 to the side wall portion 3 and between the inner side of the bead apex 8 in the tire axial direction and the inner carcass ply 11A. 5 is folded back from the inner side in the tire axial direction to the outer side and rises on the outer side of the bead apex 8. The folded-back portion of the outer carcass ply 12A has a so-called 2-0 structure that is cut off on the inner side in the tire radial direction with respect to the flange outer end P of the regular rim J.

Further, the carcass ply 12A in the inside has the tip of the folded portion extended to the outside of the flange outer end P of the rim J in the tire radial direction, whereby the carcass 10A.
May be formed in a so-called 2-0HTU configuration.

The inner carcass ply 12A may have the tip of the folded portion extending to the buttress portion as shown by the alternate long and short dash line in FIG.

As described above, the pneumatic radial tire can be modified into various types.

[0031]

SPECIFIC EXAMPLE A tire having a tire size of 215/65 R15 and having a configuration shown in FIG. 1 was prototyped according to the specifications shown in Table 1 (Examples 1 to 8) and its performance was tested. In addition, a tire having a conventional configuration (conventional example) and a tire having a configuration other than the configuration of the present application (Comparative Examples 1 and 2) were also prototyped and their performances were compared.

The test procedure is as follows. In the test, each sample tire was mounted on a 4.51 FR vehicle through a 15 × 6 1/2 -JJ rim, and the actual vehicle was run under a tire internal pressure of 200 KPa.

A) Exterior noise The vehicle exterior noise test method defined in the automobile standard JASO Z 101-83 was carried out, the vehicle was run at a speed of 60 km / h, and the overall noise was measured. Each reduction amount (dBA) of was displayed. Note that FIG. 4 is a graph showing the relationship between the outside noise and the case where the driving number ratio E1 / E2 is changed.

(B) Noise in the vehicle (road noise) The overall noise on a rough asphalt road at a speed of 50 km / h was measured by placing a microphone near the center of the driver's seat and each reduction amount was set to 0 (conventional example). d
BA) is displayed.

C) Steering stability and riding comfort In the tests of the above a) and b), it was judged by the feeling of one person riding. In Table 1, ◯ means good, Δ means slightly bad, and × means bad.

[0036]

[Table 1]

[0037]

[Table 2]

As a result of the test, in the example, the conventional example,
It was confirmed that noise can be reduced while maintaining steering stability and riding comfort, as compared with the comparative example.

[0039]

As described above, the pneumatic radial tire of the present invention has the above-mentioned structure, and can reduce the noise generated from the tire during traveling while maintaining the steering stability and the riding comfort.

[Brief description of drawings]

FIG. 1 is a right half sectional view of a tire showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating the configuration of the carcass.

FIG. 3 is a cross-sectional view showing another example of the configuration of the carcass.

FIG. 4 is a graph showing a relationship between a driving ratio of carcass cords and noise outside the vehicle.

FIG. 5 is a sectional view showing another embodiment.

[Explanation of symbols]

 2 tread part 3 sidewall part 4 bead part 5 bead core 10, 10A carcass 11, 11A inner carcass ply 12, 12A outer carcass ply 13, 14 carcass cord

Claims (2)

[Claims] 1. An inner carcass ply in which carcass cords are arranged side by side around a bead core of a bead portion from a tread portion to a side wall portion, and a sidewall portion from the tread portion to a sidewall portion radially outside the inner carcass ply. A pneumatic tire comprising a carcass consisting of an outer carcass ply in which carcass cords are arranged in parallel with each other and extending at least in the vicinity of the bead core as per unit length in a direction perpendicular to the carcass cord of the inner carcass ply. The ratio E1 / E2 of the number E1 of driving the carcass cords and the number E2 of driving the carcass cords per unit length in the direction perpendicular to the other carcass cords is 0.5.
Or more and 0.96 or less, or 1.04 or more and 1.50
A pneumatic tire characterized by being: 2. The pneumatic tire according to claim 1, wherein the carcass cord of the inner carcass ply and the carcass cord of the outer carcass ply are made of the same material and have substantially the same thickness.