JPH07156612A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce passing noise while various running performance such as rolling resistance, cornering force and the like are being maintained. CONSTITUTION:In a tread section, band plies 10 in the axial direction composed of band cords 12 the tilt angle against a tire equator C of which is roughly 90 deg. and band plies 11 in the circumferential direction composed of band cords 13 the tilt angle against the tire equator C of which is roughly 0 deg. are over- lapped so as to be formed into a band layer 9 disposed at the outer side in the radial direction of a belt layer 7, and in this case, organic fiber cords whose modulus is 200 to 1000Kg/mm<2> shall be used for each band cord of the band plies in the axial direction.

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 passing noise without deteriorating various running performances such as rolling resistance and cornering force.

[0002]

2. Description of the Related Art In recent years, as the noise outside the vehicle has become a major social problem, attention has been paid to tire noise, which is one factor of vehicle noise, and development of low-noise tires has been demanded.

As a source of noise generated from tires,
For example, it is known that air column resonance noise is generated when air passes through the air column formed by the tread groove and the ground when the tire touches the ground, and the tread pattern has been improved to reduce the air column resonance noise. .

[0004]

However, there is a limit in suppressing noise by only improving the tread pattern, and in order to further reduce noise, it is necessary to take measures on the tire structure surface other than the tread pattern. .

On the tire structure side, vibration of the belt layer and vibration of the sidewall portion are considered.

As a result of repeated investigations and studies on the factors causing vibration on the tire construction surface, the inventor has found that the vibration of the sidewall portion can be reduced by suppressing the vibration of the belt layer.

Further, in addition to the belt layer and the circumferential band ply in which band cords are arranged outside the belt layer to prevent the belt layer from rising, the band cords are arranged in the tire axial direction. By providing the arrayed axial band plies, the bending vibration energy of the belt layer is converted into heat energy by the axial band plies, and the damping effect of the tread portion and the sidewall portion can be obtained. Therefore, they have found that passing noise can be reduced, and have completed the present invention.

The present invention relates to a circumferential band ply in which a band cord disposed outside a belt layer has a band cord substantially parallel to the tire equator, and an axial band ply in which the band cord is inclined substantially at right angles to the tire equator. The object of the present invention is to provide a pneumatic tire capable of reducing passing noise during traveling while maintaining various traveling performances such as rolling resistance and cornering force on the basis of being formed by and.

[0009]

The present invention is directed to a carcass which folds around a bead core of a bead part from a tread part to a sidewall part, and a belt layer arranged inside the tread part and radially outside the carcass. And a band layer disposed radially outward of the belt layer, the band layer having an angle α with respect to a tire equator.
Comprising an axial band ply using a band cord having an angle of about 90 ° and a circumferential band ply using a band cord having an angle β with respect to the tire equator of about 0 °. Is in the radial direction,
Along with the overlap on the outside, the band cord of the axial band ply has a modulus of 200 kg / mm ² or more and 1000 kg.
The pneumatic tire is characterized by being formed by using an organic fiber having a density of not more than / mm ² .

The axial band ply may be overlapped with the circumferential band ply radially outward thereof, or may be overlapped radially inward thereof.

[0011]

The source of the tire passing noise is the vibration of the belt layer and the vibration of the sidewall portion, except for the pattern factor. Such belt layer and sidewall vibrations
For example, in a tire with a tire size of 205/55 R15, as shown in FIG. 7, by increasing the thickness (t) of the tread rubber, which is the rubber located radially outside the belt layer in the tread portion, from the road surface It is known that the vibrating force of is transmitted to the belt layer and the sidewall portion, and as a result, passing noise such as impact noise and air column resonance noise generated with the road surface is reduced.

However, as the thickness (t) of the tread rubber increases, the lateral rigidity of the tread portion decreases. As a result, as shown in the graph of FIG. 8, the cornering force decreases and the steering stability decreases. Further, by increasing the tread rubber thickness (t), the hysteresis loss increases, and as shown in the graph of FIG. 9, the rolling resistance increases during traveling, which leads to an increase in fuel consumption.

Increasing the tread rubber thickness (t) in this way reduces the passing noise, but lowers the steering stability and rolling resistance, which are the basis of the running characteristics, and thus maintains the running performance. However, in order to reduce passing noise, a new configuration is required.

The present invention is intended to solve the problem by providing the axial band ply having the above-mentioned structure.

The belt layer has a plurality of belt plies whose belt cords intersect each other so that the belt cords exert a hoop effect on each other to maintain the rigidity of the tread portion. It prevents the belt layer from protruding.

Since the axial band ply has a band cord whose angle to the tire equator is about 90 °, the axial rigidity of the tire in the tread portion is increased, and the bending vibration energy of the belt layer is increased by the axial band ply. Is converted into heat energy by and the damping effect of the tread portion and the sidewall portion is obtained. Further, since the rigidity in the tire axial direction is increased, the cornering force can be maintained, and the rigidity in the circumferential direction is not increased, so that the reduction in riding comfort is prevented. Moreover, since the topping rubber has a ply structure, a low hysteresis loss can be achieved and an increase in rolling resistance can be prevented.

The band cord of the axial band ply has a modulus of 200 kg / mm ² or more and 1000 kg / mm ^2.
It is formed by using organic fibers of mm ² or less. If the modulus is less than 200 kg / mm ² , the vibration damping effect does not occur and the effect of reducing passing noise is poor, and the modulus is 100
This is because if it exceeds 0 kg / mm ² , the rigidity of the tread portion increases and the riding comfort deteriorates.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2, a pneumatic tire 1 includes a tread portion 2, a pair of sidewall portions 3 and 3 extending inward in the tire radial direction from both sides thereof, and a bead portion 4 extending inward of the sidewall portion 3. Have.

In the pneumatic tire 1, a main body portion 6 extending from the tread portion 2 to the sidewall portion 3 to the bead portion 4 is formed.
a carcass 6 having a turn-back portion 6b which is turned around the bead core 5 from the inner side in the tire axial direction to the outer side; a belt layer 7 arranged outside the carcass 6 and inside the tread portion; A band layer 9 arranged radially outside the layer 7 is provided.

In this embodiment, the bead core 5 is located radially outward of the bead core 5 and the carcass 6 has a body portion 6a and a folded portion 6b.
A bead apex 8 having a triangular cross section and made of hard rubber is erected between and.

In this example, the carcass 6 is composed of two carcass plies 6A and 6B.
A and 6B are formed as a radial or semi-radial arrangement in which carcass cords made of organic fibers such as nylon, polyester, rayon, and aromatic polyamide are juxtaposed at an angle of 75 to 90 ° with respect to the tire equator C.
Further, the carcass cords are arranged so as to intersect with each other between the carcass plies 6A and 6B. In this example,
The height of the tip of the folded-back portion 6b from the bead base line is formed as a high turn-up which is larger than the height of the tip of the bead apex 8.

In this embodiment, the belt layer 7 includes an inner belt ply 7A arranged radially outside the carcass 6 and adjacent to the carcass 6, and an outer belt arranged outside the inner belt ply. The belt plies 7A and 7B are made of nylon, polyester, rayon,
Belt cords made of an organic fiber such as aromatic polyamide or steel are inclined at an angle of 10 to 45 ° with respect to the tire equator C and are arranged so as to intersect each other between the belt plies 7A and 7B. Tread section 2
The rigidity of is improved.

The inner and outer belt plies 7A and 7B are
In this embodiment, they are formed to have substantially the same width, and the width WB is 0.8 to 0.95 times the tread width WT.

The band layer 9 comprises an axial band ply 10 in which a band cord 12 having an angle α with the tire equator C of approximately 90 ° is arranged in parallel, and a band cord 13 having an angle β of approximately 0 ° in the tire equator C in parallel. The circumferential band ply 11 is formed so as to overlap the inside and outside of the tire radial direction.

In this embodiment, as shown in FIGS.
The axial band ply 10 overlaps with the circumferential band ply 11 at the outer side in the radial direction.

The band cord 12 of the axial band ply 10 has a modulus of 200 kg / mm ² or more and 100 or more.
It is formed by using an organic fiber cord of 0 kg / mm ² or less, for example, an aromatic polyamide fiber or a wholly aromatic polyester fiber.

In this embodiment, the band cords 12 are arranged to have a denier of 1500 d / 2 and the number of implants per 5 cm is 51, and the band cords 12 are covered with a topping rubber to form a sheet-shaped axial band ply 10. It is formed. As the rubber composition of the topping rubber, for example, those having the rubber compositions shown in Examples 1 and 2 in Table 1 are preferable.

Band cord 1 of the circumferential band ply 11
3 is formed by using an organic fiber having a high strength such as an aromatic polyamide fiber or a wholly aromatic polyester fiber, or a steel cord, and by arranging these band cords 13 and covering them with a topping rubber, a sheet resistance is obtained. It is formed.

The circumferential band ply 11 can also be formed by spirally winding in the tire circumferential direction a long strip-shaped ply obtained by coating one or more of the above band cords with topping rubber.

Such a circumferential band ply 11 is for preventing lifting of the belt layer 7 during tire running, and in the present embodiment, the ply width WP2 is formed to be slightly larger than the belt width WB. is doing. Further, in this embodiment, in order to prevent the peeling of the edge F of the belt layer 7, an edge band ply 15 is further provided to cover the edge F.

The ply width WP1 of the axial band ply 10 is substantially the same as the ply width WP2 of the circumferential band ply 11 in this embodiment. The ply width WP1 of the axial band ply 10 is the ply width W for the purpose of increasing the axial rigidity of the tread portion 2 and achieving low noise.
It is sufficient that P1 is 20% or more of the belt width WB.

The axial band ply 10 is shown in FIG.
As shown in, the inner side in the radial direction of the circumferential band ply 11,
That is, it may be provided between the belt layer 7 and the circumferential band ply 11. Furthermore, FIGS. 4, 5 and 6 show another mode of the axial band ply 10.

In FIG. 4, it is formed by an axial band ply 10A arranged in the center of the tread portion 2 and having a width WP1 0.2 to 0.5 times the belt ply width WB.

In FIG. 5, the axial band ply 10 is shown.
B is formed by arranging three ply pieces 14 with a gap in the tire axial direction. Further, in FIG. 6, the axial band ply 10C has two ply widths 1
It is formed by arranging 4 and 14 at the edge F of the belt layer 7. As described above, the present invention can be modified into various aspects.

[0035]

Specific Examples Tire Examples 1 and 2 having a tire size of 205 / 55R15 and having the configuration shown in FIG. 1 or 3.
Was prototyped according to the specifications shown in Table 1 and its performance was investigated. For comparison, a tire having a conventional configuration in which an axial band ply is not provided (conventional example) and a tire having a configuration other than the configuration of the present invention (comparative example) were also tested and their performances were compared. The test conditions are as follows.

1) Passing noise Carried out by an actual vehicle coasting test stipulated in JASO C606, a vehicle equipped with test tires was passed over a straight test course at a passing speed of 60 km / H and a distance of 50 m while coasting. Maximum passing noise was measured by a microphone installed at a distance of 7.5 m from the running center line at a midpoint of the course and at a height of 1.2 m from the test road surface.

2) Rolling resistance Measured by using a rolling resistance tester and shown by an index with the conventional example being 100. The smaller the value, the less rolling resistance the better.

3) Cornering power: Measured using a flat belt type indoor tester, and indicated by an index with the conventional example being 100. The larger the value, the better. The test results are shown in Table 1.

[0039]

[Table 1]

[0040]

As described above, the pneumatic tire of the present invention is
The band layer disposed on the outer side in the radial direction of the belt layer includes an axial band ply using a band cord inclined at about 90 ° to the tire equator and a band cord disposed at about 0 ° to the tire equator. Since the circumferential band ply and the axial band ply are overlapped with each other and the modulus of the band cord of the axial band ply is regulated, passing noise during traveling can be reduced while maintaining traveling performance.

[Brief description of drawings]

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

FIG. 2 is a developed plan view schematically showing the configurations of the belt layer and the band layer.

FIG. 3 is a sectional view showing another embodiment.

FIG. 4 is a cross-sectional view showing another aspect of the band layer.

FIG. 5 is a cross-sectional view showing another mode of the band layer.

FIG. 6 is a cross-sectional view showing another aspect of the band layer.

FIG. 7 is a graph showing the relationship between tread rubber thickness and passing noise.

FIG. 8 is a graph showing the relationship between tread rubber thickness and cornering power.

FIG. 9 is a graph showing the relationship between tread rubber thickness and rolling resistance.

[Explanation of symbols]

 2 tread part 3 sidewall part 4 bead part 5 bead core 6 carcass 7 belt layer 9 band layer 10, 10A, 10B, 10C axial band ply 11 circumferential band ply 12 band cord 13 band cord C tire equator

Claims (3)

[Claims] 1. A carcass which folds around a bead core of a bead portion from a tread portion to a sidewall portion, a belt layer disposed inside the tread portion and radially outside the carcass, and a radial outer portion of the belt layer. A pneumatic tire comprising a band layer arranged on one side, wherein the band layer is
An axial band ply comprising an axial band ply using a band cord having an angle α with the tire equator of approximately 90 ° and a circumferential band ply using a band cord having an angle β with the tire equator of approximately 0 °. The circumferential band ply overlaps inside and outside in the radial direction, and the band cord of the axial band ply has a modulus of 200 kg.
/ Mm ² or more and a pneumatic tire characterized by being formed by using a 1000 kg / mm ² or less organic fibers. 2. The pneumatic tire according to claim 1, wherein the axial band ply overlaps with the circumferential band ply radially outward. 3. The pneumatic tire according to claim 1, wherein the axial band ply overlaps the circumferential band ply inward in the radial direction.