JPS61285104A - Tire for aircraft - Google Patents

Abstract

PURPOSE:To increase a shock absorbing effect and prevent a damage of a carcass by using a specific organic fiber cord having a relatively low elastic modulus for each cord of the carcass and a belt layer and providing a covered layer around a bead core. CONSTITUTION:A tire T has a carcass constituted with two carcass plies 2, 3 folded and fixed at their ends from the inside toward the outside around a bead core 1 and a carcass ply 4 likewise folded and fixed at its end from the outside toward the inside and a belt layer 5 made of an organic fiber cord and provided outside the crown section of the carcass. In this case, the tensile elastic modulus of the cord of the carcass and the belt layer 5 is set to 5,000 kg/mm<2> or less. In addition, a covered layer 8 protectively covering the bead core 1 is provided, and this covered layer 8 is formed with a cord layer buried with an organic fiber cord in rubber having a complex elastic modulus of 70-110 kg/cm<2>.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention has sufficient load capacity, reduces damage to a portion of the aircraft caused by large deformations during repeated takeoffs and landings, and reduces impact on the aircraft body. The present invention relates to an aircraft tire in which mitigation can be effectively achieved.

[Conventional technology]

Recently, the development of aircraft has been remarkable, and as the weight and flight speed of aircraft have increased, the characteristics of safely taking off and landing at high speeds as well as being able to withstand high loads and high speeds have become more demanding.

In particular, the following characteristics are required for aircraft tires that differ from general tires.

b) Aircraft tires need to reduce the impact when an aircraft lands on a runway, stop the aircraft safely, and facilitate takeoff. It is necessary to select tire reinforcing materials.

Aircraft tires are designed to have a large amount of deflection under load, for example, approximately 28% to 38%, in order to effectively cushion the impact of the aircraft and ensure safe takeoff and landing. Therefore, it is necessary to select a tire structure and reinforcing material that can sufficiently withstand large repeated deformations.

Aircraft tires must satisfy the above ten required characteristics, but conventionally, this type of tire often has a cross-ply structure in which the carcass cords cross each other between the plies. has been done. Tires with this type of structure have low tread rigidity due to the direction in which the carcass cords are arranged, which is unfavorable in terms of wear resistance and heat generation.

Furthermore, the center of the trend protrudes due to centrifugal force accompanying high-speed rotation of the tire, causing temporary and permanent tire growth, which is unsatisfactory in terms of tire durability. Therefore, by adopting a so-called radial structure in which the carcass cords are arranged in the tire radial direction, and by arranging a belt layer in which highly elastic -1-cords are arranged at a relatively shallow angle in the tire circumferential direction inside the trend part, we have developed Radial tires with increased rigidity have recently come into use. This type of radial tire has its carcass cords arranged in the radial direction, has low lateral rigidity, and has a relatively large amount of deformation. As a result, the carcass ply around the bead core is repeatedly deformed and subjected to extensional strain, leading to repeated damage in which the carcass is likely to be damaged in this area.

[Problem to be solved]

This invention solves the problems of abrasion resistance, heat generation, and tire growth in cross-ply structures, and is based on a radial structure, with the modulus of elasticity of the carcass cords and belt layer cords set within a specific range, and the bead core. An object of the present invention is to provide an aircraft tire that enhances the effect of mitigating shock during dark landing and prevents damage to the carcass around the bead core by arranging a coating layer.

[Technical means to solve problems]

In this invention, both ends are folded back and locked around a pair of left and right bead cores, and the cord is fixed at an angle of 60 degrees to the tire equatorial plane.
A carcass arranged at an angle of ~90° and a cord placed outside the carcass at an angle of ~30° with respect to the tire equatorial plane.
a bead apex arranged in an area surrounded by the bell 1 layer arranged at a cord angle of ', a bead apex arranged in an area surrounded by the carcass and its folded part, and a coating layer for covering and protecting the bead nier 1a, the carcass and the heald layer. All cords are mechanical fiber cords with a tensile modulus of 5000 kg/m2 or more F, and the coating layer is an organic fiber cord embedded in rubber with a complex modulus of elasticity (E*) of 70 to 110 kg/cd. This is an aircraft tire characterized by a cord layer.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a schematic view of the right half of a cross-sectional view of the tire of the present invention. In the figure, the tire T consists of two carcass plies 2.3 and bead 1a1' which are secured by folding back the ends around the bead core 1 from the inside to the outside.
) The carcass is composed of a single carcass ply 4 which is folded back and locked at the end from the outside to the inside, and has a belt layer 5 made of organic fiber cord on the outside of the crown portion of the carcass. The cord of the carcass is placed at an angle of 60° to 90° with respect to the tire equatorial plane,
In particular, in order to increase the lateral rigidity of the tire, it is preferable to arrange the plies in the range of 79° to 80° so as to cross each other. Next, the tensile modulus of the cord of the carcass and belt layer is 5000 kg/mm2 or less, preferably 1000 kg
/Constructed of organic fiber cords of Tsuru 2 or less. As mentioned above, aircraft tires have a large amount of deflection when loaded.
Moreover, it is subjected to repeated bending deformation due to high-speed rotation.

Therefore, aircraft tires not only have sufficient bending fatigue resistance under large deformations, but also prevent ply separation between the carcass and the belt layer due to the difference in stiffness near the boundary between the carcass and the belt layer at both ends. That is important.

Therefore, the present invention provides a relatively low elastic modulus for both the carcass ply cord and the belt layer cord, particularly 5000 k
By using an organic fiber cord of less than g/is', the bending durability is increased, and the modulus of elasticity of the carcass cord and the belt layer cord are made close to each other, thereby effectively suppressing stress concentration at the end of the heald layer. This made it possible.

As is clear from Table 1, the organic fiber cords used for the carcass cord and belt layer coating are rayon, polyester, vinylon, aramid, and nylon. The carcass coat and the cord of the belt layer are made of substantially the same material, for example, by using nylon 66 for both the carcass cord and the cord of the belt layer, the carcass effectively absorbs the repeated impact from the trend part of the bell 1 layer. The absorption is relaxed and damage to the tread part can be prevented.
15% to 75% of the tire cross-sectional height H in the area surrounded by 3a
It has a bead apex 7 extending to a height Hl of %. This bead apex 7 has the function of making the fit with the wheel even stronger and increasing the lateral rigidity of the tire side part.If the height is less than 15%, these functions are insufficient, but if the height is less than 15%, If it exceeds this value, the tire's impact-reducing effect will be inhibited. The dynamic elastic modulus (E*) of the bead apex was measured using an Iwamoto Seisakusho Elasticity Spectrometer at 70°C, initial strain 10%, amplitude 2.0%, frequency 50Hz, 4 crane length x 30 crane length x 2. 200kgf/cd~150 as measured using a crane-thick sample
0kgf10J, preferably 900kgf/-
That's all. By using a bead apex having such characteristic values, it is possible to maintain the lateral rigidity of the tire during high speed rotation.

Next, in the present invention, a covering layer 8 for covering and protecting the bead core 1 is arranged. This coating layer 8 prevents the carcass around the bead core from being subjected to strong elongation due to repeated deformation of the tire and from abrasion occurring between the hard bead core and severe damage to the carcass in this area. This is the purpose. Therefore, the covering layer 8 is a cord layer in which organic fiber cords, such as nylon, polyester, or rayon cords are embedded in rubber having a complex modulus of elasticity (E lines) of 70 to 110 kg/aj, preferably a cord made of the same material as the carcass. It is composed of

By setting the Tan δ of the embedded rubber in the range of 0.10 to 0.25, heat generation is suppressed and the effect of reducing damage to the carcass is further enhanced.

Here, the complex modulus of elasticity ('E) and Tan δ are measured using the same measuring method as the bead apex.

In addition, in the present invention, stress concentration at both ends of the belt layer is effectively absorbed by arranging the cushion rubber 6 whose thickness gradually decreases from both ends of the belt layer between the belt layer and the carcass below both ends of the belt layer. , can be relaxed. Cushion rubber 6 has a 3009 modulus of 70 to 150 kg.
/cm2 range is used.

Further, in the present invention, the modulus of the topping rubber of the carcass and belt layer is a relatively soft rubber corresponding to the elastic modulus of the cord, for example, a 300% modulus of 80 to 160k.
g/cd range is used.

EXAMPLE Aircraft tires with a tire size of 26 x 6.6 had the basic structure shown in FIG. 1 and had the specifications shown in Table 2. Tires were prototyped and the durability of each tire was evaluated.

Durability test was conducted using TSO-C62C as specified by the National Civil Aviation Administration standards.
The number of take-offs and taxi simulations leading to failure according to the test is shown.

Table 2 showing the evaluation results shows that all examples using nylon 66 or polyester for the heald layer cord and steel, aramid, or rayon for the band meet the durability test standards. .

〔Effect of the invention〕

Like the ridges, the aircraft tire of the present invention uses a specific organic fiber cord with a relatively low elastic modulus for both the carcass cord and the cord of the belt layer, and also has a coating layer placed around the bead core, making it suitable for aircraft take-off and landing. An aircraft tire with excellent durability can be obtained by effectively achieving cushioning of the aircraft body and preventing damage to the carcass at the tire bead.

[Brief explanation of the drawing]

FIG. 1 shows the right half of a sectional view of the tire of the invention. T-・-tire, l-・・bead core, 2.3.4
- carcass ply, 5 - belt layer, 6 - cushion rubber, 7 - bead apex, 8 - covering layer.

Claims (2)

[Claims] (1) Both ends are folded back and locked around a pair of left and right bead cores, and the cord is 60° to 90° to the tire equatorial plane.
A carcass arranged at an angle of 0°, a belt layer arranged outside the carcass at a cord angle, a bead apex arranged in an area surrounded by the carcass and its folded part, and the surroundings of the bead core are covered and protected. The cords of the carcass and the belt layer are both organic fiber cords having a tensile modulus of 5000 kg/mm^2 or less, and the covering layer has a complex modulus of elasticity (E*
) is a cord layer in which organic fiber cords are embedded in rubber having a weight of 70 to 110 kg/cm^2. (2) The tensile modulus of the carcass cord is 10,000 kg
The aircraft tire according to claim 1, which has a particle diameter of /mm^2 or less.