JP3502174B2 - Pneumatic radial tires for aircraft - Google Patents

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 used in an aircraft such as a jet airliner, and more particularly to an inner belt made of a cord extending substantially in the circumferential direction while zigzag and cutting the inner belt. The present invention relates to a pneumatic radial tire for aircraft having a belt composed of an outer belt that protects from damage due to trauma.

[0002]

2. Description of the Related Art In addition to reducing weight, standing waves during high speed running and cutting due to external damage
Suppressing or preventing the occurrence of peel-off failures is an important performance requirement for pneumatic radial tires for aircraft. In order to meet this demand, for example, as disclosed in JP-A-5-193306, (1) the belt is composed of an inner belt close to the carcass and an outer belt close to the tread. ) The inner belt crosses the tire equatorial plane at an angle A of 5 to 15 degrees, and is bent at both ends of the belt to form a zigzag pattern. (3) The outer belt intersects the tire equatorial plane at an angle B larger than the angle A, and a plurality of outer belts in which cords cut at both ends of the belt are embedded in rubber.
Pneumatic pneumatic radial tires made of ply have been proposed, and the intended purpose has been achieved for the time being.

[0003]

However, it has been found that the conventional tire as described above has a drawback that an unexpected belt separation failure occurs at the beginning. That is, it has been found that separation failures tend to occur near the both ends of the outer belt, particularly at the cord cut ends of the outermost belt ply on the innermost side in the radial direction.

An object of the present invention is to reduce the weight of pneumatic radial tires for aircraft, to suppress or prevent the occurrence of standing waves during high speed running and cut peel-off failures due to external damage, and also the occurrence of belt separation failures. Is to suppress or prevent.

[0005]

In order to achieve the above object, the tire of the present invention is a pneumatic radial tire for aircraft provided with a radial carcass, a belt and a tread, wherein (1) the belt is It is composed of an inner belt on the side close to the carcass and an outer belt on the side close to the tread. (2) The inner belt is 5 with respect to the tire equatorial plane.
A plurality of inner belts having cords embedded in rubber that extend in the circumferential direction while zigzag by being bent at both ends of the belt and intersecting at an angle A of 15 degrees.
(3) The outer belt is composed of a plurality of outer belt plies in which the cords that intersect the tire equatorial plane at an angle B larger than the angle A and that are cut at both ends of the belt are embedded in rubber. (4) The width of the inner belt is approximately the same as or slightly larger than the ground contact width when the tire having the rim assembled to the normal rim is filled with the normal inner pressure and the normal load is applied, that is, the ground contact width is 0.9 to 1 ．
It is about 15 and (5) the width of the outer belt is 0.6 to 0.85 of the ground contact width when the tire after the rim is assembled to the regular rim is filled with the regular internal pressure and the regular load is applied. It is a characteristic pneumatic radial tire for aircraft.

In order to achieve the above object, in the tire of the present invention, the cord of the outermost belt ply in the radial direction and the cord of the innermost belt ply in the radial direction are provided near both ends of the outer belt. Is preferably a pneumatic radial tire for an aircraft having a distance of at least the cord diameter of the outer belt ply.

[0007]

In the present invention, the inner belt crosses the equatorial plane of the tire at an angle A of 5 to 15 degrees and is bent at both ends of the belt to zigzag, and a plurality of cords extending substantially in the circumferential direction are embedded in the rubber. Since the inner belt ply is used, it is possible to reduce the number of belt plies while keeping the total strength and reduce the weight, and it is possible to suppress or prevent the generation of standing waves during high-speed traveling. Further, in the present invention,
The outer belt crosses the tire equatorial plane at an angle B larger than the angle A, and the cords cut at both ends of the belt are composed of a plurality of outer belt plies embedded in rubber.・ Peel-off failure is prevented. The cords forming the outer belt ply are preferably arranged in the opposite direction to the tire equatorial plane so as to intersect with each other between the adjacent belt plies.

The inner belt is formed by laminating layers (inner belt plies) in which cords extending substantially circumferentially in a zigzag manner by bending at both ends of the belt are embedded in rubber (inner belt ply). It has very high bending rigidity. The outer belt has a layer in which cords cut at both ends of the belt are embedded in rubber (outer belt ply), so that the bending rigidity in the vicinity of both ends of the belt is relatively low.
When the belt is deformed into a flat surface just below the load when the tire is used, a large circumferential shear strain occurs between the inner belt and the outer belt near the ground contact end. In the conventional tire, the inner belt width and the outer belt width are almost the same as the ground contact width, and the circumferential shear strain in the vicinity of the ground contact end becomes large immediately below the above load, and in the vicinity of both ends of the outer belt, especially in the radial innermost direction. Separation failure was likely to occur at the cord cutting ends of both outer belt plies. In the present invention, the width of the outer belt is 0.6 to 0.85 of the tire ground contact width,
Since the circumferential shear strain concentration portion is avoided, the occurrence of separation failure is suppressed or prevented. If this value is greater than 0.85, separation failure is likely to occur, and if it is less than 0.6, the cut reaches the inner belt directly and cut peel-off failure is likely to occur.

Further, as described above, the conventional tire is apt to have a separation failure particularly at the cord cutting ends of both ends of the outermost belt ply on the innermost side in the radial direction. Then, in the vicinity of both ends of the outer belt, the cord of the outermost belt ply in the radial direction and the innermost belt of the radial outermost
Since the distance from the cord of the ply is equal to or larger than the cord diameter of the outer belt / ply, large circumferential shear strain between the inner belt and the outer belt near the ground contact end is mitigated, and the occurrence of separation failure is suppressed or prevented. To be done.

[0010]

EXAMPLES The present invention will be described below with reference to the tires of Examples 1 and 2 according to the present invention and conventional tires. Both are radial tires for aircraft, the tire size is A
PR1050 × 395R16.

A radial tire 1 for an aircraft according to a first embodiment of the present invention shown in FIG. 1 has a bead core 7 having a round cross section at a bead portion and is rubber-coated 189.
This bead is a carcass 6 consisting of 6 plies with 0d / 3 66 nylon cords arranged in the radial direction.
Moored to core 7. Four of the six plies are wound around the bead core 7 from the inside to the outside of the tire, and the remaining two plies are wound from the outside to the inside along the outside of the winding. It is a so-called up / down structure that is returned. Other structural members such as a flipper and a chafer are not shown.
The belt 2 arranged inside the tread 5 outside the crown portion of the radial carcass 6 is composed of an inner belt 3 on the side close to the carcass and an outer belt 4 on the side close to the tread. 10 for the equatorial plane
The outer belt 4 is composed of four inner belt plies in which rubber of 1890d / 4 66 nylon cords embedded in rubber crosses each other at an angle A of degrees and bends at both ends of the belt in a zigzag manner to extend in the circumferential direction.
Is a pair of outer belt plies in which a 1890d / 3 66 nylon cord, which is cut at both ends of the belt and intersects the tire equatorial plane at an angle B of 20 degrees larger than the angle A, is embedded in rubber. Consists of. The width of the inner belt 3 is 286 mm, and the regular rim 1050
Normal internal pressure of the tire after assembling the rim to × 395R16 13.4
It is almost the same as the ground contact width of 280 mm when the bag is filled with kg / cm ² and a regular load of 15515 kg is applied. The outer belt 4 is composed of two outer belt plies, but the outer (tread side) belt ply has a width of 218 mm and a ground contact width of 0.78, and the inner belt ply has a width of 232 mm. There is a contact width of 0.83. In the present invention, the width of the outer belt means the maximum width of the outer belt. Therefore, the width of the outer belt 4 of the tire of Example 1 is 0.83 which is the ground contact width. In the tire of Example 1 according to the present invention,
As shown in FIG. 2, in the vicinity of both ends of the outer belt 4, the distance a between the cord of the outermost belt ply in the radial direction and the cord of the innermost belt ply in the radial direction is a.
Is 0.7 of the cord diameter b of the outer belt ply.

In the tire of Example 2 according to the present invention, the distance a between the cord of the outermost belt ply in the radial direction and the cord of the innermost belt ply in the radial direction is close to both ends of the outer belt 4. The tire is the same as the tire of Example 1 except that the cord diameter b of the outer belt ply is 1.1.

The tire of the conventional example is the outer side (tread side) of the two outer belt plies forming the outer belt 4.
The belt ply has a width of 252 mm and a ground contact width of 0.85, and the inner belt ply has a width of 238 m.
m is the same as the tire of Example 1 except that it has a ground contact width of 0.90 and the outer belt 4 has a ground contact width of 0.90.

The belts of the tires of Examples 1 and 2 according to the present invention and the tire of the conventional example were evaluated for separation resistance under the same conditions.

The evaluation test was carried out by applying a load of 13200 kg to a tire filled with an internal pressure of 13.6 kg / cm ² at a speed of 6
1 straight running at 10 km with an indoor drum tester at 4 km / h
As a cycle, 1000 times of traveling is set as a target condition for complete traveling. The drum test is interrupted every 50 times after running 600 times, and the test is continued while checking the presence or absence of separation with a holographic tester.

Since the tire of Example 1 cleared the target condition of complete running without any abnormality after 1000 times of running, when the test running was further continued, 1200 times of running resulted in two small separation failures on the circumference of the tire. It was The tire of Example 2 cleared the target condition of complete running without any abnormality after running 1000 times, and further continued test running 1
There were no abnormalities after running 200 times. The tire of the conventional example had a separation failure almost all around the tire after traveling 750 times.

From the above-mentioned test results, as compared with the tire of the conventional example in which the width of the outer belt 4 is 0.9 of the ground contact width, the embodiment according to the present invention in which the width of the outer belt 4 is 0.83 of the ground contact width. It can be seen that the tire of No. 1 has excellent separation resistance. In the vicinity of both ends of the outer belt 4, the distance a between the cord of the outermost belt ply in the radial direction and the cord of the innermost belt ply in the radial direction is 1. It can be seen that the tire of Example 2 according to the present invention, which is No. 1, is a tire having further excellent separation resistance performance.

[0018]

According to the present invention, the weight of pneumatic radial tires for aircraft is reduced, and the occurrence of standing waves during high-speed running and cut peel-off failure due to external damage are suppressed or prevented, and belt separation failure occurs. It has become possible to suppress or prevent.

[Brief description of drawings]

FIG. 1 is a meridional section schematic view of a tire of Example 1 according to the present invention.

FIG. 2 is an enlarged meridian section schematic view of two belt plies at the belt end.

[Explanation of symbols]

1 Pneumatic radial tires for aircraft 2 belts 3 inner belt 4 outer belt 5 tread 6 Radial carcass 7 Bead Core

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Claims (2)

(57) [Claims] 1. A pneumatic radial tire for an aircraft provided with a radial carcass, a belt and a tread, wherein the belt comprises an inner belt close to the carcass and an outer belt close to the tread. Is
(2) The inner belt is 5 to 1 with respect to the tire equatorial plane.
(3) The outer belt is composed of a plurality of inner belt plies in which rubber is embedded with cords that extend substantially circumferentially while zigzag by intersecting at an angle A of 5 degrees and bending at both ends of the belt. And the cords that are crossed at an angle B larger than the angle A and are cut at both ends of the belt are composed of a plurality of outer belt plies embedded in rubber, and (4) the width of the inner belt is equal to the regular rim. The width of the outer belt is about the same as or slightly larger than the ground contact width when the tire after the rim assembly is filled with the regular internal pressure and the regular load is applied. A pneumatic radial tire for aircraft, which has a ground contact width of 0.6 to 0.85 when filled and applied with a normal load. 2. The cord of the outer belt ply is located near both ends of the outer belt, and the distance between the cord of the outer belt ply radially innermost and the cord of the inner belt ply radially outermost. The pneumatic radial tire for an aircraft according to claim 1, wherein the pneumatic radial tire has a diameter equal to or larger than a diameter.