JPH11321233A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic radial tire preventing edge separation in a belt layer while reducing weight, and improving riding comfort performance, and moreover excellent in tire performance such as moving performance, high speed durability and rolling resistance. SOLUTION: A belt body formed by embedding a plurality of reinforcing cords formed of organic fiber cords or steel cords, in a matrix so as to be parallel with each other is spirally folded in such a way that the reinforcing cords are inclined with respect to the circumferential direction of a tire, to form a spiral belt layer 5 disposed on the outside of a carcass layer 2 in a tread part 3. A single steel cord belt layer 4 with a plurality of steel cords arranged to incline with respect to the circumferential direction of the tire is arranged on the outside of the spiral belt layer 5, and the steel cord belt layer 4 is made narrower than the spiral belt layer 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire having an improved belt structure.
A pneumatic radial tire that prevents edge separation in the belt layer while reducing the weight, improves ride comfort, and improves tire performance such as athletic performance, high-speed durability, and rolling resistance. .

[0002]

2. Description of the Related Art Hitherto, a steel cord belt layer utilizing the excellent strength and elastic modulus of a steel cord has been used in a belt portion of a pneumatic radial tire. But,
Since the steel cord belt layer has cut end faces at both ends in the tire width direction, stress is concentrated on the cut end face, and there is a disadvantage that separation is easily generated between the steel cord belt layer and the rubber layer.

Therefore, in order to prevent edge separation of the belt layer, a tape obtained by rubberizing a nylon cord as a belt reinforcing layer (belt cover layer) on the outer peripheral side of the steel cord belt layer has a cord angle substantially in the tire circumferential direction. (Japanese Patent Publication No. 4-47618). However, such a method has the drawback that it is difficult to reduce the weight of the tire, and that the riding comfort is deteriorated due to an increase in ruggedness during running.

On the other hand, in order to avoid the occurrence of cut end faces at both ends in the width direction of the belt layer, one or a plurality of organic fiber cords are rubberized in parallel to each other to form a belt-like body across the width of the belt layer. (Japanese Patent Application Laid-Open No. 4-173404). However, in this belt layer, although the separation resistance is at a level that is not a problem, the belt cord is an organic fiber cord, so the belt rigidity is insufficient, and it is easy to swell at the center of the tire, it is difficult to control the shape, and the cornering force is low. There were drawbacks such as lower exercise performance due to lowering.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to prevent edge separation in a belt layer while improving the ride comfort while reducing the weight, and to improve the exercise performance, high-speed durability and rolling performance. It is an object of the present invention to provide a pneumatic radial tire having improved tire performance such as dynamic resistance.

[0006]

In order to achieve the above object, a pneumatic radial tire according to the present invention has a reinforcing cord made of a plurality of organic fiber cords or steel cords parallel to a carcass layer in a tread portion. A spiral belt layer in which the reinforcing cord is spirally folded so that the reinforcing cord is inclined with respect to the tire circumferential direction is arranged, and a plurality of steel cords are provided outside the spiral belt layer. A single-layer steel cord belt layer is arranged so as to be inclined with respect to the tire circumferential direction, and the width of the steel cord belt layer is smaller than that of the spiral belt layer.

As described above, the spiral belt layer having no cut end face is provided on both sides in the tire width direction outside the carcass layer in the tread portion, and the steel cord belt layer outside the spiral belt layer is narrower than the spiral belt layer. Further, it is possible to prevent separation due to stress concentration on the edge portion of the belt layer during running. Further, since the tension of the reinforcing cord is hardly reduced in the spiral belt layer, the rigidity of the cord itself can be reduced while the weight of the cord itself is reduced, so that the riding comfort can be improved.

Further, in addition to the spiral belt layer, a single steel cord belt layer in which a plurality of steel cords are arranged so as to be inclined with respect to the tire circumferential direction is provided outside the spiral belt layer. In addition, it is possible to easily control the shape of the belt layer and improve tire performance such as exercise performance, high-speed durability and rolling resistance.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 illustrates a pneumatic radial tire according to an embodiment of the present invention. In FIG. 1, a carcass layer 2 in which a plurality of carcass cords are arranged in a radial direction is mounted between a pair of left and right bead cores 1, 1. From the outside. On the outer side of the carcass layer 2 in the tread portion 3, a spiral body in which a plurality of reinforcing cords are embedded in a matrix in parallel with each other and spirally folded so that the reinforcing cords are inclined with respect to the tire circumferential direction. The belt layer 5 is disposed over one circumference of the tire.

As shown in FIG. 2, the spiral belt layer 5 includes a plurality of reinforcing cords 6, preferably 5 to 10 cords, which are buried in a matrix in parallel with each other to form a strip 7, and the strip 7 is continuously formed. It can be formed by spirally winding (or thread-winding) into a tubular body and crushing the tubular body along its longitudinal direction. Such a spiral belt layer 5 has a two-layer structure with a flat cross section. As shown in FIG. 3, the reinforcing cords cross each other between the lower belt layer 5d and the upper belt layer 5u. The cord angle θ of the spiral belt layer 5 with respect to the tire circumferential direction is 1
It is set in the range of 5 ° ≦ θ ≦ 45 °. This is because if the cord angle θ with respect to the tire circumferential direction deviates from the above range, the durability of the belt layer decreases.

As the reinforcing cord of the spiral belt layer 5, an organic fiber cord or a steel cord can be used. Organic fiber cord, for example, aromatic polyamide fiber, polyarylate fiber, polyparaphenylene benzobisoxazole fiber, polyvinyl alcohol fiber, rayon fiber, polyethylene terephthalate fiber,
One or two or more fibers selected from polyethylene-2,6-naphthalate fibers are twisted. The matrix in which the reinforcing cords of the spiral belt layer 5 are embedded is not limited to rubber, but may be plastic such as urethane resin.

On the other hand, on the outside of the spiral belt layer 5,
A single-layer steel cord belt layer 4 in which a plurality of steel cords are arranged so as to be inclined with respect to the tire circumferential direction is disposed over one circumference of the tire. The steel cord belt layer 4 has cut end faces at both ends in the tire width direction, and is narrower than the spiral belt layer 5. The cord angle α of the steel cord belt layer 4 with respect to the tire circumferential direction is set in a range of 15 ° ≦ α ≦ 65 °.

In the steel cord belt layer 4, the cord angle α with respect to the tire circumferential direction is preferably in the range of 15 ° ≦ α <45 ° in order to further improve high-speed durability.
This is because, as described in "Structural Mechanics of Radial Tires" in Vol.
In the vicinity of the complementary angle 35.3 ° of tan ^-1 √2 = 54.7 °, even if the belt layer is pulled in the tire circumferential direction, the interlayer shear strain of the belt layer is sharply reduced and the belt circumferential rigidity is maintained. .

In the steel cord belt layer 4, in order to further reduce the rolling resistance, the cord angle α with respect to the tire circumferential direction is preferably in the range of 45 ° ≦ α ≦ 65 °. This is the same as the above-mentioned Journal of the Rubber Association of Japan
As described in the issue “Structural Mechanics of Radial Tire”, when the cord angle is tan ⁻¹ √2 = 54.7 °, the interlayer layer shear deformation of the belt layer is suppressed, so that the energy loss in the belt layer decreases, As a result, the rolling resistance decreases.

In the present invention, as described above, the spiral belt layer 5 having no cut end face is provided on both sides in the tire width direction on the outer side of the carcass layer 2 in the tread portion 3, and the steel cord belt layer 4 on the outer side is formed by the spiral. By making the width smaller than that of the belt layer 5, separation due to stress concentration on the belt layer edge portion during running can be prevented. In addition, since the spiral belt layer 5 does not have a cut end face at both ends in the tire width direction, the tension of the reinforcing cord is hardly reduced, so that the cord itself can be reduced in weight and low in rigidity, thereby improving ride comfort. Can be improved. Therefore, by combining the spiral belt layer 5 and the steel cord belt layer 4, it is possible to prevent edge separation in the belt layer and to improve ride comfort while reducing the weight.

Further, the spiral belt layer 5 alone has insufficient belt rigidity, so that it tends to swell at the center of the tire, and it is difficult to control the shape.
Since the steel cord belt layer 4 is provided outside the spiral belt layer 5, the shape of the belt layer can be easily controlled, and the tire performance such as exercise performance, high-speed durability, and rolling resistance can be improved. It is possible.

[0017]

EXAMPLES The following tires 1 to 4 of the present invention and conventional tires 1 and 2 were manufactured with a tire size of 195 / 70R14. For these test tires, high-speed durability, rolling resistance, exercise performance, ride comfort,
The tire mass was evaluated, and the results are shown in Table 1. In addition,
The tires 1 and 3 of the present invention have the cord angle α of the steel cord belt layer with respect to the tire circumferential direction in the range of 15 ° ≦ α <45 °, and the tires 2 and 4 of the present invention have the tire circumference of the steel cord belt layer. Cord angle α to direction
Is set in a range of 45 ° ≦ α ≦ 65 °.

The tire 1 of the present invention has a belt structure shown in FIGS. 4 (A) and 4 (B). The spiral belt layer 5 is made of an aromatic polyamide fiber cord 1500
A 10 mm wide belt-shaped body obtained by rubberizing D / 2 at a driving density of 50 ends / 50 mm is continuously wound spirally, and the cord angle θ with respect to the tire circumferential direction is 30.
°. The steel cord belt layer 4 was composed of a 140 mm wide sheet obtained by rubberizing steel cords 2 + 2 (0.25) with a number of ends of 40/50 mm, and the cord angle α to the tire circumferential direction was 30 °.

The tire 2 of the present invention has a belt structure shown in FIGS. 4 (A) and 4 (B). The spiral belt layer 5 is made of an aromatic polyamide fiber cord 1500
A 10 mm wide belt-shaped body obtained by rubberizing D / 2 at a driving density of 50 ends / 50 mm is continuously wound spirally, and the cord angle θ with respect to the tire circumferential direction is 30.
°. The steel cord belt layer 4 was composed of a 140 mm wide sheet obtained by rubberizing steel cords 2 + 2 (0.25) at a driving density of 40 ends / 50 mm, and the cord angle α to the tire circumferential direction was 55 °.

The tire 3 of the present invention has a belt structure shown in FIGS. 4 (A) and 4 (B). Spiral belt layer 5 has a width of 1 × 3 (0.15) of steel cord rubberized with 30 ends / 50 mm driving density.
A 0 mm strip was continuously spirally wound to form a cord angle θ of 30 ° with respect to the tire circumferential direction. The steel cord belt layer 4 was composed of a 140 mm wide sheet obtained by rubberizing steel cords 2 + 2 (0.25) with a number of ends of 40/50 mm, and the cord angle α to the tire circumferential direction was 30 °.

The tire 4 of the present invention has a belt structure shown in FIGS. 4 (A) and 4 (B). Spiral belt layer 5 has a width of 1 × 3 (0.15) of steel cord rubberized with 30 ends / 50 mm driving density.
A 0 mm strip was continuously spirally wound to form a cord angle θ of 30 ° with respect to the tire circumferential direction. The steel cord belt layer 4 was composed of a 140 mm wide sheet obtained by rubberizing steel cords 2 + 2 (0.25) at a driving density of 40 ends / 50 mm, and the cord angle α to the tire circumferential direction was 55 °.

Conventional tire 1 As shown in FIGS. 5 (A) and 5 (B), two steel cord belt layers 4 are laminated so that cords intersect each other between the layers, and both ends of the steel cord belt layers 4 are connected to each other. A belt structure is provided in which a nylon cord reinforcing layer 11 is provided outside the nylon cord reinforcing layer 10 so as to cover the entire belt layer. The steel cord belt layer 4 has a rubber cord 2 + 2 (0.25) rubberized at a driving density of 40 ends / 50 mm and has a width of 15 mm.
It was composed of a sheet having a thickness of 0 mm (inside) and a width of 140 mm (outside), and the cord angle α with respect to the tire circumferential direction was 30 °. The nylon cord reinforcing layers 10 and 11 are each made of a tape obtained by rubberizing nylon fiber cords 840D / 2 at a driving density of 70 ends / 50 mm, and the cord angle with respect to the tire circumferential direction is substantially 0 °.
I made it.

Conventional tire 2 has a belt structure shown in FIGS. 6 (A) and 6 (B). That is,
It was the same as the tire 1 of the present invention except that the steel belt layer 4 was not provided. Condition Rim size: 14 × 5 1/2 JJ Air pressure: 1.9 kg / cm ² , load: 450 kg High-speed durability : After mounting the test tire on a drum testing machine having a drum diameter of 1707 mm and running according to the JATMA high-speed durability test The speed was increased by 10 km / hr every 10 minutes, and the distance until the tire was broken was measured. The evaluation results are shown as an index with the conventional tire 1 being 100.
The higher the index value, the better the high-speed durability.

Rolling resistance : Rolling resistance was measured by an indoor drum type tire rolling resistance tester. The evaluation results are shown as indices with the reciprocal of the measured value of the conventional tire 1 being 100.
The larger the index value, the lower the rolling resistance. Exercise performance : The test tire was mounted on a 2.5-liter domestic car and the steering feeling was evaluated by three test drivers. The evaluation result was 100
It was shown by an index. The larger the index value, the better the steering stability (motor performance).

Ride comfort : The test tires were mounted on a domestic 2.5-liter class car, and a feeling test was performed by three test drivers to evaluate ride comfort.
The evaluation results are shown as an index with the conventional tire 1 being 100. The larger the index value, the better the ride comfort.

Tire mass : Three tires were randomly extracted from tires manufactured for evaluation, and the tire mass was measured. The evaluation results are shown as an index with the conventional tire 1 being 100.
The smaller the index value, the lighter the weight.

[0027]

As is clear from Table 1, the tires 1 to 4 of the present invention are superior in ride comfort to the conventional tire 1 and have good tire performance such as exercise performance, high-speed durability and rolling resistance. Met. In the tires 1 to 4 of the present invention,
Since the rigidity of the reinforcing cord itself of the belt layer is reduced (weight reduction), the tire mass is equal to or less than that of the conventional tire 1.

[0029]

As described above, according to the present invention, a belt-like body in which a plurality of reinforcing cords made of organic fiber cords or steel cords are buried in a matrix in parallel with each other outside the carcass layer in the tread portion. A spiral belt layer spirally folded so that the reinforcing cord is inclined with respect to the tire circumferential direction is arranged, and a plurality of steel cords are inclined with respect to the tire circumferential direction outside the spiral belt layer. By arranging a single-layer steel cord belt layer arranged in the following manner, and making the steel cord belt layer narrower than the spiral belt layer, it is possible to prevent edge separation in the belt layer while reducing the weight and to improve ride comfort. Performance can be improved,
In addition, tire performance such as exercise performance, high-speed durability, and rolling resistance can be improved.

[Brief description of the drawings]

FIG. 1 is a meridional sectional view illustrating a pneumatic radial tire of the present invention.

FIG. 2 is a perspective explanatory view illustrating a spiral belt layer in the present invention.

FIG. 3 is an explanatory plan view showing the belt structure in FIG. 1;

4A and 4B show an example of a belt structure of the pneumatic radial tire according to the present invention, wherein FIG. 4A is a sectional view and FIG. 4B is a plan view.

5A and 5B show an example of a belt structure of a conventional pneumatic radial tire, wherein FIG. 5A is a sectional view and FIG. 5B is a plan view.

6A and 6B show another example of a belt structure of a conventional pneumatic radial tire, wherein FIG. 6A is a sectional view and FIG. 6B is a plan view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bead core 2 Carcass layer 3 Tread part 4 Steel cord belt layer 5 Spiral belt layer 6 Reinforcement cord 7 Belt

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI B60C 9/22 B60C 9/22 B (72) Inventor Yasuo Morikawa 2-1 Oiwake, Hiratsuka-shi, Kanagawa Prefecture Yokohama Rubber Co., Ltd. Hiratsuka Manufacturing Co., Ltd. Inside

Claims (3)

[Claims] 1. A band formed by embedding a plurality of organic fiber cords or steel cords in parallel in a matrix outside a carcass layer in a tread portion in a tire circumferential direction. A spiral belt layer that is spirally folded so as to be inclined is arranged, and a single steel cord belt layer in which a plurality of steel cords are arranged so as to be inclined with respect to the tire circumferential direction is provided outside the spiral belt layer. A pneumatic radial tire in which the steel cord belt layer is arranged to have a width smaller than that of the spiral belt layer. 2. The pneumatic radial tire according to claim 1, wherein a cord angle θ of the spiral belt layer with respect to a tire circumferential direction is 15 ° ≦ θ ≦ 45 °. 3. The pneumatic radial tire according to claim 1, wherein a cord angle α of the steel cord belt layer with respect to a tire circumferential direction is 15 ° ≦ α ≦ 65 °.