JP2000016035A - Pneumatic radial tire for aircraft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve anti-rim deviation performance in a pneumatic radial tire for an aircraft using a cable bead in a bead part. SOLUTION: In a pneumatic radial tire for an aircraft in which both end parts 3a, 3b of a carcass layer 3 are wound around cable beads 4 having a circular cross section embedded in right and left bead parts 1, plural reinforcement layers 6 comprising one or plural reinforcement cords continuously wound in a tire circumferential direction are embedded from a bead toe part 1T to exceed a tire radial direction outer side end 4x of the cable bead 4 in a tire inner side part of the bead part 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pneumatic radial tire for an aircraft, and more particularly, to a pneumatic radial tire for an aircraft with improved rim displacement resistance.

[0002]

2. Description of the Related Art In general, a pneumatic radial tire for an aircraft used under conditions of high internal pressure and high load, as shown in FIG.
Is embedded, and the end 13 a of the carcass layer 13 is wound around the cable bead 12. Since large deformation occurs in the bead portion 11 due to a large vertical deflection due to a high load, a bead core arranged in the bead portion 11 is required to have a structure with high strength. Therefore, a cable bead 12 having a circular cross section in which a plurality of steel wires are spirally wound around a core wire is used.

However, when the bead portion 11 is greatly deformed as shown in FIG. 4 at the time of cornering or receiving a lateral force due to the use of such a cable bead 12 having a circular cross section, the bead toe T side is deformed so as to rise from the rim X. Thereby, the contact pressure distribution with the rim X from the bead toe T to the bead heel H of the bead base portion 11A is
As shown by the solid line in FIG. 2, while the bead toe T side is greatly reduced, the position C just below the center of the cable bead 12 is reduced.
Significantly higher. For this reason, there was a problem that the center portion 11a of the bead base portion 11A was greatly rubbed due to repeated deformation of the bead portion under a high load and was worn as shown by the dotted line in FIG. 3 (poor rim displacement resistance).

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic radial tire for an aircraft which can improve rim displacement resistance in a pneumatic radial tire for an aircraft using a cable bead at a bead portion. Is to do.

[0005]

The present invention, which achieves the above object, provides a pneumatic radial tire for an aircraft in which both ends of a carcass layer are wrapped around a cable bead having a circular cross section embedded in right and left beads. In the tire inner portion of the bead portion, a plurality of reinforcing layers in which one or more reinforcing cords are continuously wound in the tire circumferential direction so as to exceed the tire radial direction outer end of the cable bead from the bead toe portion. It is characterized by being buried.

As described above, since the reinforcing cord is provided on the bead toe side of the bead portion by providing a plurality of reinforcing layers continuously wound in the tire circumferential direction, the bead portion is large when cornering or receiving a lateral force. Even if it is deformed, the bead toe portion can be maintained in a state of being pressed against the rim by the effect of winding the reinforcing cord. For this reason, the contact pressure of the bead base portion also bears on the bead toe side, so that the contact pressure immediately below the center of the cable bead can be reduced, and wear at the center portion of the bead base portion can be suppressed.

[0007]

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 shows an essential part of a pneumatic radial tire for an aircraft according to the present invention, wherein 1 is a bead portion, 2 is a sidewall portion, and 3 is a reinforcing cord made of an organic fiber cord at 70 to 90 ° with respect to the tire circumferential direction.
The carcass layers 4, which are arranged in an inclined manner, are cable beads having a circular cross section in which a plurality of small-diameter steel wires 4b are spirally wound around one large-diameter steel core wire 4a.

A plurality of carcass layers 3 are mounted between the right and left bead portions 1, and both end portions 3 a of at least one of the carcass layers 3 sandwich the bead filler 5.
The tire is wound around the cable bead 4 embedded in the bead portion 1 so as to be folded from the inside to the outside of the tire. Further, both ends 3b of at least one outer carcass layer 3 are wound around the cable bead 4 from the outside to the inside of the tire. Although not shown, a belt layer acting as a tension-resistant layer in which reinforcing cords made of organic fiber cords are arranged so as to intersect with the tire in the direction opposite to the tire circumferential direction on the outer peripheral side of the carcass layer of the tread portion. A plurality of belt layers having a reinforcing cord made of an organic fiber cord and a belt layer wound spirally at substantially 0 ° in the tire circumferential direction are embedded.

The bead portion 1 is formed such that the inner peripheral surface 1a of the bead base portion 1A facing the rim X is gradually inclined outward from the bead toe T toward the bead heel H in the tire radial direction. In the tire inner part of the bead part 1,
Two annular reinforcing layers 6 in which one or a plurality of reinforcing cords are embedded continuously and spirally wound around a rubber strip in the tire circumferential direction are embedded.

An inner reinforcing layer 6A adjacent to the carcass layer 3 extends from the vicinity of the tire radially outer end 5a of the bead filler 5 to the tire radially inner side along the carcass layer 3, and the rubber strip is wound and moved at the bead toe portion 1T. The outer reinforcing layer 6B is formed by being folded in the opposite direction. The outer reinforcing layer 6B extends from the bead toe portion 1T beyond the tire radial outer end 4x of the cable bead 4.

As described above, the bead toe portion 1T of the bead portion 1
The reinforcement layer 6 is provided on the side of the tire in which the reinforcement cord is continuously wound in the tire circumferential direction, and the inner portion of the cable bead 4 is reinforced from the bead toe portion 1T. When the bead portion 1 is greatly deformed, the bead toe T is prevented from floating from the rim X on the side of the bead toe T, and the contact pressure of the bead base portion 1A with the rim X is distributed from the bead toe T to the bead heel H as shown by the broken line in FIG. Since the load can also be borne by the bead toe portion 1T, the contact pressure at the bead base portion inner peripheral surface position (bead base position) C immediately below the center of the cable bead 4 can be reduced. Therefore, even if the bead portion 1 is repeatedly deformed under a high load, the center portion of the bead base portion 1A does not rub largely, so that it is possible to suppress abrasion and improve the rim displacement resistance. Can be.

In the present invention, the reinforcing cord of the reinforcing layer 6 is preferably wound at an angle of 30 ° or less with respect to the tire circumferential direction. When this winding angle exceeds 30 °,
Lifting from the rim X on the bead toe T side of the bead base 1A cannot be effectively prevented. As the reinforcing cord of the reinforcing layer 6, an organic fiber cord can be preferably used. Among them, a cord having excellent heat shrinkability is preferable, and for example, nylon and the like can be preferably cited.

The total strength of the reinforcement cords of the two reinforcement layers 6 is preferably such that the tire circumferential component is 30 to 70% of the carcass layer tension Q acting on the cable bead 4 when an internal pressure is applied. Here, the term “at the time of internal pressure load” refers to TRA (TIRE AND RIM ASSOCIATION) 1998 A
It is the air pressure at the time of no load specified in IRCRAFT YEAR BOOK. The carcass layer tension Q acting on the cable bead 4 is such that the tire internal pressure is P (kgf / mm ² ), the radius of the carcass layer at the tread portion is Ra (mm), and the radius of the carcass layer at the tire cross-sectional maximum width position is Rc. (mm), it is determined by the following equation.

Q = P × (Ra ² −Rc ² ) / 2 In the two reinforcing layers 6, the positions of the radially outer ends 6a and 6b of the inner reinforcing layer 6A and the outer reinforcing layer 6B are as follows.
From the tire radial direction sectional center line J extending in the direction orthogonal to the tire axis through the sectional center O of the cable bead 4 and from the line L having an angle of 45 ° to the tire inward direction with respect to the sectional center O from the sectional center O It is better to be on the outside. When the positions of the outer ends 6a and 6b are located radially inward of the line L in the tire radial direction, the effect of winding the reinforcing cord around the bead toe portion is reduced, and it is difficult to effectively prevent the floating from the rim X on the bead toe T side.

Tire radial outer end 6a of inner reinforcing layer 6A
Can be the position of the parallel line K located outside the tire by a length corresponding to the diameter of the cable bead 4 having a circular cross section from the center line J, and the tire diameter of the outer reinforcing layer 6B. The upper limit position of the outer peripheral end 6b in the direction can be the position of the center line J. Outer end 6a,
If 6b is located outside the upper limit position in the tire radial direction, a further increase in the effect of winding around the bead toe portion cannot be expected, resulting in an unnecessary increase in weight. Outer end 6a
Desirably, a range a between the center line J and the parallel line K is set. The outer peripheral end 6b is a range b between the line L and the center line J. Further, the positions of the tire radial outer ends 6a and 6b of the inner reinforcing layer 6A and the outer reinforcing layer 6B are as follows.
You may make it reverse.

The position of the inner end (turning point) 6c in the tire radial direction of the inner reinforcing layer 6A and the outer reinforcing layer 6B is determined by the contact S1 between the center line J and the inner peripheral surface 1a of the bead base 1A.
And a range c between lines M1 and M2 drawn parallel to the tire axis at a contact point S2 between the center line J and the outer peripheral surface of the cable bead 4 in the tire radial direction. Inside edge 6c
Is located radially inward of the line M1 in the tire radial direction, the inner end 6
When c is located outside the line M2 in the tire radial direction, the reinforcing effect of the bead toe portion 1T is reduced, and it becomes difficult to effectively improve the rim displacement resistance.

In the present invention, the example in which two layers of the reinforcing layer 6 are provided in the above-described embodiment has been described. Preferably, the plurality of reinforcing layers 6 have a configuration in which the bead toe portion 1A is folded back as shown in FIG. 1.
It is preferable to provide an even number of layers. Further, when a plurality of reinforcing layers 6 more than two layers are arranged, the above-described total reinforcing cord strength indicates the total strength of the plurality of layers, and the outer reinforcing layer 6
The terminal positions of the reinforcing layers located outside of B can be in the same range as the outer reinforcing layer 6B, and it is preferable that the terminal positions do not overlap.

[0018]

EXAMPLES Tires 1 to 3 of the present invention having two reinforcing layers as shown in FIG. 1 and conventional tires having no reinforcing layer were produced, respectively, as shown in FIG. The characteristics of the reinforcing layers in the tires 1 to 3 of the present invention are as shown in Table 1. Each of these test tires has a rim size of 50
The rim was mounted on a rim of × 20.0R22 and subjected to an evaluation test for rim displacement resistance under the following measurement conditions.
Were obtained.

Rim Displacement Resistance Each test tire was mounted on an indoor drum testing machine at an air pressure of 177 PSI, and under a load of 45200 LBS at a speed of 1 hour / hour.
Landing at 80 mile / h for 35 seconds, then taxi at 40 mile / h for 92 seconds,
After repeating 0 times, the wear amount of the bead base immediately below the cable bead was measured, and the result was compared with that of the conventional tire by 10 times.
The evaluation was made with an index value of 0. The smaller the value, the smaller the abrasion loss and the better the rim displacement resistance.

[0020]

[Table 1]

From Table 1, it can be seen that the tire of the present invention can greatly reduce the wear of the bead base immediately below the cable bead and can improve the rim displacement resistance.

[0022]

As described above, the present invention relates to a pneumatic radial tire for an aircraft in which both ends of a carcass layer are wound around a cable bead having a circular cross section. A plurality of reinforcing layers in which one or more reinforcing cords are continuously wound in the tire circumferential direction are buried so as to exceed the tire radial outer end, so that the bead toe portion rises from the rim when the bead portion is deformed. , The wear of the bead base immediately below the cable bead can be suppressed, and the rim displacement resistance can be improved.

[Brief description of the drawings]

FIG. 1 is a tire meridian sectional view showing an example of a main part of an aircraft pneumatic radial tire of the present invention.

FIG. 2 is a graph showing a contact pressure distribution with a rim at a bead base portion.

FIG. 3 is a tire meridian sectional view showing a main part of a conventional pneumatic radial tire for aircraft.

4 is a cross-sectional view of a principal part of the tire meridian showing a state in which the bead part in FIG. 3 is deformed.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 bead portion 1A bead base portion 1T bead toe portion 1a inner peripheral surface 3 carcass layer 3a, 3b end 4 cable bead 4x outer end 5 bead filler 5a outer end 6 reinforcing layer 6A inner reinforcing layer 6B outer reinforcing layer 6a, 6b outer end 6c Inner edge O Cross-sectional center H Bead heel T Bead toe X Rim

Claims (4)

[Claims] 1. A pneumatic radial tire for an aircraft wound around a cable bead having a circular cross section in which both end portions of a carcass layer are embedded in left and right bead portions, the inside of the bead portion is connected to the cable from a bead toe portion. A pneumatic radial tire for aircraft having a plurality of reinforcing layers in which one or more reinforcing cords are continuously wound in the tire circumferential direction so as to extend beyond a tire radially outer end of a bead. 2. The pneumatic radial tire for an aircraft according to claim 1, wherein the reinforcing cords of the plurality of reinforcing layers are wound at an angle of 30 ° or less with respect to the tire circumferential direction. 3. A tire circumferential component of a total strength of the reinforcing cords of the plurality of reinforcing layers is set to 30 to 70% of a carcass layer tension acting on the cable bead when an internal pressure is applied.
Or the pneumatic radial tire for aircraft according to 2. 4. The pneumatic radial tire for an aircraft according to claim 1, wherein said reinforcing cord comprises an organic fiber cord.