JPH09226317A - Radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve vibration characteristics without sacrificing the maneuvering stability by making the cord angle to the circumferential direction of a center part of an inside layer of a belt formed by a pair of shoulder parts with the center part interposed between them. SOLUTION: In order to restrain the vibration of a tread shoulder part, the tension of a belt layer shoulder part is increased to increase the antiplane flexural rigidity, that is, the flexural rigidity Gy round Y-axis in a model of a belt. Especially, to increase the tension burden of a shoulder belt 2-2 of the belt layer on the outside in the tire radial direction, the code angle to the tire circumferential direction of the belt is made smaller. Accordingly, if the shoulder belt angle of the belt layer is made smaller in the circumferential direction and on the contrary, the center belt angle is made larger, the tension burden on the belt layer in the circumferential direction is higher at the shoulder part and lower at the center part so as to improve the vibration characteristics of a band which becomes a problem in respect of load noise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial tire, and more particularly to a radial tire having improved vibration and riding comfort without sacrificing steering stability.

[0002]

2. Description of the Related Art Conventionally, in a radial tire, the belts 1 and 2 shown in FIG. 3 were usually set at 20 to 26 degrees with respect to the tire circumferential direction. It was said that it was difficult to achieve both stability and vibration / riding comfort. Both steering stability and vibration / riding comfort have been frequently achieved in the past by changing the tire contour shape, but it has not yet reached a sufficient level. In addition, it has been attempted to change the structure of the bead portion, but in this case, the steering stability and the vibration / riding comfort are contradictory required characteristics, so that the effect is limited.

[0003]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a tire having improved vibration and riding comfort without sacrificing steering stability by optimizing the arrangement of belts. .

[0004]

In order to achieve the above object, the present invention employs the following constitutions. That is, a carcass composed of at least one carcass ply including a cord forming substantially 90 degrees with respect to the tire equatorial plane, and a plurality of cords arranged outside the carcass in the radial direction are embedded in the coated rubber. A radial tire comprising two rubber-coated cord layers formed by laminating the cords so that the cord directions are opposite to each other with the tire equator line sandwiched at an acute angle to the tire circumferential direction, (1) Each layer constituting the belt is composed of a center portion and a pair of shoulder portions arranged so as to sandwich the center portion. (2) Cords of the inner layer of the belt in the circumferential direction of the center portion. The angle is smaller than the cord angle with respect to the circumferential direction of the shoulder portion, and (3) the cord angle with respect to the circumferential direction of the center portion of the outer layer of the belt is the circumferential angle of the shoulder portion. It is characterized by greater than a cord angle with respect to direction.

The width of the center portion of each layer constituting the belt is preferably 30 to 70% of the total width of the belt layers of each layer.

In the present invention, the cord angle of the center portion of the inner layer of the belt with respect to the circumferential direction is in the range of 5 to 15 degrees, and the angle of the shoulder portion with respect to the circumferential direction is larger by 5 degrees or more and 10 to 20 degrees. And the cord angle with respect to the circumferential direction of the shoulder portion of the outer layer of the belt is 5
In the range of -15 degrees, the angle of the center portion with respect to the circumferential direction is preferably 10 degrees or more and 25-35 degrees.

If the width difference between the center portions of the inner layer and the outer layer of the belt is 10 to 25 mm, the center belt ends of the belt layers will not coincide at the same position in the tire axial direction, Since there is no sharp step in the flexural rigidity distribution, failure can be prevented, which is preferable.

It is preferable that at least one of the layers constituting the belt is separated from the center portion and the shoulder portion because the cord angle of the center portion and the shoulder portion of each layer can be easily set during manufacturing.

It is preferable that at least one of the layers constituting the belt is integrated in the center portion and the shoulder portion because the rigidity distribution of the center portion and the shoulder portion becomes smooth.

In order to improve the vibration characteristics, it is necessary to suppress the vibration that enters the tire from the road surface and reduce the road noise, but the vibration of the road surface is transmitted to the tire as the vibration of the shoulder portion of the tread and passes through the side portion. Transmitted to the rim. Therefore, if the vibration of the shoulder portion of the tread is suppressed, the vibration characteristic is improved. In order to suppress the vibration of the tread shoulder portion, the out-of-plane bending rigidity of the belt layer shoulder portion may be increased by increasing the tension of the belt layer shoulder portion. Here, the out-of-plane bending rigidity refers to the bending rigidity G _y around the Y axis (having an axis in the tire axial direction) according to the model of the belt shown in FIG. In particular, the shoulder belt 2-of the belt layer 2 on the outer side in the tire radial direction.
It is effective to increase the tension load of 2. In order to increase the load of tension, the cord angle of the belt with respect to the tire circumferential direction may be made small. Therefore, if the shoulder belt angle of the belt layer 2 is set small in the circumferential direction and the center belt angle of the belt layer 2 is set large, the tension load in the circumferential direction of the belt layer 2 is high in the shoulder portion and low in the center portion. The vibration transfer characteristics, especially the vibration characteristics in the 100 to 400 Hz band, which is a problem with road noise, are improved.

However, if it is left as it is, the in-plane bending rigidity (G _z shown in FIG. 4) of the center belt portion of the belt layer 2 becomes weak and the steering stability deteriorates. The cord angle can be lowered to increase the in-plane bending rigidity of this portion.

Further, the shoulder belt 1 of the belt layer 1
If the cord angle of −2 with respect to the circumferential direction is made higher than that of the center belt, the enveloping characteristics of the crown portion including the tire belt are improved, and thus the riding comfort is improved.

That is, according to the present invention, the belt layers 1 and 2 are divided into a center belt portion and a shoulder belt portion, and the cord angle thereat is optimized to balance the rigidity of the belt layers 1 and 2 and to vibrate and ride. It improves comfort and steering stability.

Here, the belt layer total width of each layer is a1, a2.
And the center belt widths are b1 and b2 respectively, b
It is 30 that 1 / a1 and b2 / a2 are set to 30 to 70%.
% Or less, the center belt width is too narrow and the influence of the shoulder belt becomes strong, so that the out-of-plane bending rigidity of the belt portion becomes too high and the riding comfort performance deteriorates. This is because the effect of can not be expected.

Further, although the center belt and the shoulder belt of each layer are integrated or arranged in abutment with each other, separate members may be arranged so as to overlap each other. In this case, depending on the way of overlapping, there is an advantage that options such as a tire with emphasis on steering stability and a tire with emphasis on economy are increased.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The tires prototyped as examples are
The tire shown in FIG. 3 has a tire size of 195 / 65R1.
The cord used for the belt layer of this tire is a steel cord having an elastic modulus of 16,000 kg / mm ² ,
The elastic modulus of the belt layer is 4,800 kg / mm ² , the total width of the belt layer 1 is 180 mm, and the center belt width is 80 m.
m, the width of each of the two shoulder belts is 50 mm,
The belt layer 2 has a total width of 170 mm and a center belt width of 60 m.
The width of each of the two shoulder belts is 55 mm. As shown in Table 1, eight types of prototypes were produced by changing the angle of the belt. In these tires, the center belt and the shoulder belt are arranged to face each other. A tire having a conventional structure was also manufactured as shown in Table 1. All of these tires are the same except for the belt structure.

The test was carried out by mounting the above-mentioned tire on a rim of 6JJ-14 at an internal pressure of 2.0 kg / cm ^{2, and making} it 2000
It was mounted on a cc passenger car, and a test driver drove on uneven roads and highways to evaluate the riding comfort and steering stability. As shown in Table 1, the tire of the conventional example is shown as 100 as shown in Table 1, and the larger the value, the better. The road noise test was also installed on a domestic 2000cc passenger car, and the internal noise at a speed of 50km / h was 100-400.
It measured about the Hz band. This is also represented by an index with the conventional example being 100, and the larger the number, the better.

[0018]

[Table 1]

[0019]

As is clear from the above description, it is possible to provide a tire having improved vibration and riding comfort without sacrificing steering stability by optimizing the belt arrangement as in the present invention. it can.

[Brief description of drawings]

FIG. 1 is a belt arrangement example showing an embodiment of the present invention.

FIG. 2 is a belt arrangement example showing another embodiment of the present invention.

FIG. 3 is a sectional view in the tire width direction showing a conventional example.

FIG. 4 is a diagram illustrating bending rigidity of a belt.

[Explanation of symbols]

T tire 1 belt layer 1 1-1 center belt 1-2 shoulder belt 2 belt layer 2 2-1 center belt 2-2 shoulder belt a1 total width of belt layer 1 b1 center portion width of belt layer 1 a2 belt layer 2 Total width b2 Center part width of belt layer 2 G _Y Out-of-plane bending rigidity G _{Z In-} plane bending rigidity

Claims (6)

[Claims] 1. A carcass consisting of at least one carcass ply including a cord forming substantially 90 degrees with respect to an equatorial plane of a tire, and a plurality of cords arranged radially outside of the carcass in a rubber covered with rubber. And a belt formed by laminating two rubber-coated cord layers embedded in the tire so that the cord directions are opposite to each other with the tire equator line sandwiched at an acute angle with respect to the tire circumferential direction. In the tire, (1) each layer constituting the belt is composed of a center portion and a pair of shoulder portions arranged so as to sandwich the center portion, and (2) the circumference of the center portion of the inner layer of the belt. The cord angle with respect to the direction is smaller than the cord angle with respect to the circumferential direction of the shoulder portion, (3)
A radial tire in which a cord angle of the outer layer of the belt with respect to the circumferential direction of the center portion is larger than a cord angle of the shoulder portion with respect to the circumferential direction. 2. The radial tire according to claim 1, wherein the width of the center portion of each layer constituting the belt is 30 to 70% of the total width of the belt layers of each layer. 3. The cord angle of the center portion of the inner layer of the belt with respect to the circumferential direction is in the range of 5 to 15 degrees, and the angle of the shoulder portion with respect to the circumferential direction is larger than that by 5 degrees or more.
It is in the range of 0 to 20 degrees, the cord angle of the shoulder portion of the outer layer of the belt with respect to the circumferential direction is in the range of 5 to 15 degrees, and the angle of the center portion with respect to the circumferential direction is more than 10 degrees.
3. The radial tire according to claim 1, wherein the radial tire has a range of 25 degrees to 35 degrees, which is greater than or equal to 10 degrees. 4. The radial tire according to claim 1, wherein a difference in width between center portions of the inner layer and the outer layer of the belt is 10 to 25 mm. 5. The radial tire according to claim 1, wherein at least one of the layers constituting the belt is separated at the center portion and the shoulder portion. 6. The radial tire according to claim 1, wherein at least one of the layers constituting the belt is integrated in the center portion and the shoulder portion.