JPH09277802A - Pneumatic semi-radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assure a high action performance and control stability without increasing the weight of tire by composing a carcass ply of one layer of semi- radial ply, the layer being one of rubber-covered cord layers where the cord is hurried in the covering rubber at a specified angle to the circumferential direction of tire. SOLUTION: A bent-back part 2A of a carcass ply 2 extends to the outside in the radial direction and reaches the inner side in the radial direction of both ends 3A of a belt 3. The carcass ply 2 is composed of one layer of semi- radial ply formed by burring a cord in a covering rubber at the angle of 70-87 degrees to the circumferential direction of tire. The belt 3 is composed of two rubber-covered cord layers 31, 32 so that they are laminated in the reverse direction to each other with the direction of the cord being at an angle of 20-38 degrees to the circumferential direction of tire and with the equatorial plane of tire interposed therebetween. The layer 31 being in contact with the carcass ply 2 is arranged reversely to the cord direction of the ply 2 in the cord direction with the equatorial plane being interposed therebetween.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire for passenger cars, and particularly to a pair of left and right bead cores arranged in a bead portion, and extending from a crown portion to both bead portions through both side wall portions. The present invention relates to a pneumatic tire for a passenger vehicle, comprising a carcass ply wound around the bead core and moored at a bead portion, and a belt arranged radially outside a crown portion of the carcass ply in the radial direction.

[0002]

2. Description of the Related Art Conventionally, a pneumatic tire for a passenger vehicle has a pair of left and right bead cores arranged in a bead portion and extends from a crown portion to both bead portions through both side wall portions.
A radial tire having a carcass ply made of a radial ply wound around the bead core and moored at the bead portion and a belt arranged radially outside the crown portion of the carcass ply is the most preferable. It is common.

[0003]

In recent years, passenger cars, especially heavy-duty vehicles, have tended to have higher output and higher performance, and the dynamic performance, steering stability, and durability required for tires are extremely high. It is at a high level. In order to respond to this, tires having a heavy structure have been developed. However, it is necessary to reduce the unsprung weight of the vehicle due to the weight balance of the vehicle, low fuel consumption performance, etc., and the weight reduction of the tire itself is required. However, reducing the weight of tires and enhancing their athletic performance, steering stability and durability are contradictory requirements, and it has been extremely difficult to achieve both at the same time.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a tire having a high degree of dynamic performance and steering stability performance without increasing the weight of the tire.

[0005]

In order to achieve the above object, a pneumatic tire of the present invention comprises a pair of left and right bead cores arranged in a bead portion, and a bead core through a side wall portion and both bead portions. A carcass ply moored to the bead portion by winding the bead core.
In a pneumatic tire comprising a belt arranged radially outside a crown portion of the carcass ply,
(1) The carcass ply folds the bead core from the inside to the outside to form a bead core fold portion, and the bead core fold portion extends outward in the radial direction, and the belt ends in the radial direction. (2) The carcass ply reaches the inside, and the carcass ply is a semi-radial rubber-coated cord layer in which a cord is embedded in a coated rubber at an angle of 70 to 87 degrees with respect to the tire circumferential direction. (3) at least two rubber-coated cord layers in which the belt is laminated so that the cord direction is an acute angle with respect to the circumferential direction of the tire and the tire equatorial lines are sandwiched in mutually opposite directions. (4) Of the at least two rubber-coated cord layers forming the belt, the rubber-coated cord layer adjacent to the carcass ply has a cord direction of 2 with respect to the tire circumferential direction. Pneumatic semi-pneumatic vehicle for passenger cars, characterized in that they are arranged at an angle of 38 to 38 degrees so as to be opposite to each other with the code direction of the semi-radial plies forming the carcass ply sandwiching the tire equator line. It is a radial tire.

The pneumatic tire of the present invention has the above-mentioned structure, and in particular, in the carcass ply, the bead core is folded back from the inside to form the bead core folding portion, and the bead core folding portion is formed. It extends outward in the radial direction and reaches the inner side in the radial direction at both ends of the belt. Moreover, the carcass ply has a cord embedded in the covering rubber at an angle of 70 to 87 degrees with respect to the circumferential direction of the tire. As it consists of one layer of rubber coated cord layer, semi-radial ply, carcass ply cord crossing layer is formed over the entire side wall part of the tire. As a result, the carcass ply is lighter than a two-layer heavy structure tire, but the rigidity of the tire is improved, and steering stability is improved. Excellent tire performance can be obtained.

In the pneumatic tire of the present invention, as described above, the carcass ply comprises the rubber-coated cord layer in which the cord is embedded in the coated rubber at an angle of 70 to 87 degrees with respect to the circumferential direction of the tire. Yes, 1-ply semi-radial
Tires. When the code angle of the carcass ply with respect to the tire circumferential direction is smaller than 70 degrees, it becomes difficult to manufacture a tire having a desired size, and a 90 degree code is used.
Tire performance is significantly reduced compared to radial radial tires. On the other hand, when the code angle of the carcass ply with respect to the tire circumferential direction is larger than 87 degrees, the above cord intersecting layer is not formed, and thus the rigidity of the tire is not improved. In the pneumatic tire of the present invention, as described above, among the at least two rubber-coated cord layers forming the belt, the layer adjacent to the carcass ply has a code direction of 20 to 20 with respect to the circumferential direction of the tire. The semi-radial plies forming the carcass ply are arranged at an angle of 38 degrees so as to be opposite to each other across the tire equator line. If the cord direction is smaller than 20 degrees with respect to the tire circumferential direction, the belt rigidity becomes too large, and if it is larger than 38 degrees, the belt rigidity becomes too low, and in any case, the rigidity of the carcass is balanced. Disappear.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments according to the present invention and conventional examples will be described below. Both have tire sizes of 2
It is 05 / 60R15. The tire of the example was extended to the bead cores 1 from the crown portion through a pair of left and right bead cores 1 arranged in the bead portion, both side wall portions, and wound around the bead core 1 and moored to the bead portion. A pneumatic tire comprising a carcass ply 2 and a belt 3 arranged radially outside of a crown portion of the carcass ply 2, wherein the carcass ply 2 has a bead core 1 folded back from the inside. The bead core folding portion 2A is formed, and the bead core folding portion 2A is formed.
Extends toward the outside in the radial direction and reaches both ends 3A of the belt 3 inward in the radial direction. Carcass
The overlap width W between the bead core folding portion 2A of the ply 2 and both end portions 3A of the belt 3 is 20 mm.
The carcass ply 2 is a single-layer semi-radial ply in which a cord is embedded in a coated rubber at an angle of 82 degrees with respect to the tire circumferential direction. The belt 3 is composed of two rubber-coated cord layers 31 and 32 that are laminated so that the cord direction is at an angle of 24 degrees with respect to the tire circumferential direction and are opposite to each other with the tire equator line in between. Of the two rubber-coated cord layers 31 and 32 forming the carcass ply 2
The rubber-coated cord layers 31 adjacent to each other are arranged so as to be opposite to each other across the tire equator line from the code direction of the carcass ply 2.

In the conventional pneumatic tire, the carcass ply 2 is covered at an angle of 90 degrees with respect to the tire circumferential direction.
The pneumatic tire is substantially the same as the pneumatic tire of the above-described example except that the radial ply is formed by embedding the cord in the coated rubber.

A comparison test of lateral rigidity and longitudinal rigidity was carried out on the pneumatic tire of the example according to the present invention and the pneumatic tire of the conventional example. As a result of the comparative test, assuming that the lateral rigidity and the longitudinal rigidity of the pneumatic tire of the above-mentioned conventional example were 100, the lateral rigidity and the longitudinal rigidity of the pneumatic tire of the above-mentioned example were 105 and 110, respectively. Regarding the tire weight, the pneumatic tires of the examples according to the present invention and the pneumatic tires of the conventional examples had almost the same values.

[0011]

From the above evaluation results, the pneumatic semi-radial tires of the examples according to the present invention have improved lateral rigidity and longitudinal rigidity of the tires as compared with the conventional pneumatic radial tires. I understand.

[Brief description of drawings]

1 is a sectional view (left half) of a meridian of a tire according to the present invention.

[Explanation of symbols]

 1 Bead Core 2 Carcass Ply 3 Belt

Claims (1)

[Claims] 1. A pair of left and right bead cores arranged in the bead portion, and a carcass moored to the bead portion by extending from the crown portion to both bead portions through both side wall portions and winding the bead core. In a pneumatic tire including a ply and a belt arranged radially outside a crown portion of the carcass ply, (1) the carcass ply has the bead core folded back from the inside to the bead core. Forming a folded-back portion, the bead-core folded-back portion extending outward in the radial direction and reaching the inner side in the radial direction of both end portions of the belt, (2) the carcass ply is 70 in the circumferential direction of the tire. Through 8
Consisting of a semi-radial ply of a rubber-coated cord layer in which the cord is embedded in the coated rubber at an angle of 7 degrees,
(3) The belt comprises at least two rubber-coated cord layers laminated such that the cord direction is an acute angle with respect to the circumferential direction of the tire and the tire equatorial lines are sandwiched in opposite directions. 4) Of the at least two rubber-coated cord layers forming the belt, the rubber-coated cord layer adjacent to the carcass ply has a code direction of 20 to 38 degrees with respect to the tire circumferential direction, A pneumatic semi-radial tire for a passenger vehicle, wherein the semi-radial plies forming the carcass ply are arranged so as to be opposite to each other with respect to the cord direction and the tire equator line.