JP2975609B2 - Pneumatic radial tire - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pneumatic radial tire, and more particularly to a pneumatic radial tire used for an aircraft such as a jet airliner.

[Conventional technology]

2. Description of the Related Art In recent years, pneumatic radial tires have been used in aircraft such as jet airliners. The pneumatic radial tire receives a large impact (drop) load at a high speed at the time of takeoff and landing of the aircraft, so that not only is it required to have durability to withstand the high speed and large load, but also the current aircraft is compared at the airport. In many cases, taxiing (taxiing) is performed over a long distance, and therefore, high performance is required for the durability and running performance at the time of taxing as well as tires used for general vehicles.

In particular, at the time of landing of the aircraft, the bending of the sidewall increases due to the falling load, and the shear strain between the carcass layers of the sidewall increases.

In order to improve this, in a conventional pneumatic radial tire, a rubber sheet (squeegee) is inserted between the carcass layers, and the rubber layer between the carcass is simply thickened.

However, this pneumatic radial tire has a disadvantage that the weight of the rubber layer between the carcass layers is increased not only to the sidewalls but also to an unnecessary portion such as a tread portion, so that the weight is extremely increased.

[Problems to be solved by the invention]

An object of the present invention is to provide a pneumatic radial tire that can improve the durability of a side wall carcass without significantly increasing the weight in consideration of the above fact.

[Means and actions for solving the problem]

According to the present invention, at least two or more inner upcarcass layers made of organic fiber cords coated with a coating rubber and oriented substantially at 90 ° to the circumferential direction of the tire and a plurality of outer layers are formed. A pneumatic radial tire for an aircraft having a composite carcass layer composed of a down carcass layer and at least one or more belt layers radially outside a crown portion of the composite carcass layer in a tire radial direction, including a tire rotation axis In the cross section, the length from the intersection P between the outermost carcass surface and the equatorial plane along the outermost carcass surface to the end of the belt layer is LB, and the intersection P between the outermost carcass surface and the equatorial plane along the outermost carcass surface. L is the length from
When the distance between the cord and the cord between adjacent carcass plies measured perpendicular to the carcass surface and the cord is GM, and the cross-sectional diameter of the cord is DC, the relationship of GM / DC is in the region of L / LB ≦ 0.9, In the region of GM / DC <0.22 0.9 <L / LB ≦ 1.1, GM / DC> 0.40 in the region of GM / DC> 0.20 L / LB> 1.1.

Therefore, the purpose of increasing the gauge between the cords between the carcass layers in the tire radial direction on the inner side in the tire radial direction with respect to the vicinity of the end portion in the tire width direction of the belt layer is to reduce the carcass caused by the bending deformation of the carcass caused when the tire is bent. This is to prevent fatigue of the rubber or the adhesive layer between the rubber and the cord due to shear strain between the layers, and it is necessary to increase the thickness of the gauge between the cords at a portion where bending deformation is large during running.

As a result, the region of L / Lb ≦ 0.9 is a region where the belt is located, and the bending deformation of the upper carcass is suppressed by the belt. Therefore, there is little distortion between the carcass layers and the gauge between the carcass layers does not need to be thickened. Therefore, the upper limit of the interlayer gauge was determined to be GM / DC <0.22 in order to prevent an increase in the mass of the tire due to an extra gauge increase.

Further, the region of L / Lb> 1.1 is the portion where the bending deformation during running is the largest, and it is necessary to increase the interlayer gauge. The lower limit of the interlayer gauge is set to GM / DC> 0.40 by experiments and the like.
I decided.

In addition, the range of 0.9 <L / Lb ≦ 1.1 is intermediate between the two ranges, and the level of the bending deformation generated during running is also within the range of the 2nd range.
Although it is an intermediate level between the two areas, it is necessary to secure a certain amount of gauge, so the lower limit of the interlayer gauge was determined to be GM / DC> 0.20 by experiments and the like.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1, the pneumatic radial tire 10
A pneumatic radial tire for an aircraft is provided with a four-layer upper carcass 12 as a strength member for maintaining the internal pressure of filled air and a two-layer down carcass 14 as an outermost carcass. Each carcass has a carcass cord 13 formed of industrial organic fibers (eg, nylon, polyester, aramid, etc.).
(FIG. 2) are disposed substantially at 90 ° to the tire circumferential direction.

As shown in FIG. 2, the carcass cord 13 is covered with a coating rubber 15.

As shown in FIG. 1, the upper carcass 12 has its end portion wound from the inside of the bead core 16 in the tire width direction to the outside in the tire width direction and is folded back. Are wound from the outside in the tire width direction of the bead core 16 to the inside in the tire width direction and are folded back, so that each carcass has a so-called up-down structure.

The outer periphery of each carcass wound around the bead core 16 is covered with a rubber layer 18 to form a sidewall 20 and a bead portion 22. The bead portion 22 determines the size of the inner circumference of the radial tire 10, and secures the fitting with the rim 24.

A belt layer 26 is arranged along the down carcass 14 on the radially outer side of the down carcass 14 at the radially outer end of the pneumatic radial tire 10 to secure rigidity. A tread portion 30 of a thick rubber layer is formed on the outer side of the belt layer 26 in the tire radial direction. The tread portion 30 is a portion that actually comes into contact with the ground, and therefore has a sufficient thickness to withstand abrasion and damage.

Here, the length LB from the intersection P of the belt layer 26 and the equatorial plane 15 to the end 26A of the belt layer 26 along the down carcass 14 in the tire cross section including the rotation axis, and the length L from the intersection P In the region where the ratio (L / LB) is L / LB ≦ 0.9, the carcass cord between adjacent carcass layers measured on a plane perpendicular to the surface 14A of the down carcass 14 and perpendicular to the carcass cord 13 shown in FIG. The distance GM between the cable 13 and the carcass cord 13 and the cord cross-sectional diameter DC = (1.103d + 3247) / 10000mm (where d
Is the total denier number) and the relationship is GM / DC / 0.22.

In the region of 0.9 <L / LB ≦ 1.1, 0.20 <GM / DC.

In the region of 1.1 <L / LB, 0.40 <GM / DC.

For this reason, the carcass cord 13 between the adjacent carcass layers in the tire radial direction inside from the vicinity of the end 26A of the belt layer 26.
The distance between the wire and the carcass cord 13 is increased, and the durability against shear strain is improved.

Further, in the present invention, the distance between the carcass cords 13 between the adjacent carcass layers from the vicinity of the end 26A of the belt layer 26 to the outer side in the tire radial direction, that is, the thickness of the squeegee does not increase, and the weight of the squeegee does not increase so much. Never invite.

(Experimental Example) A pneumatic radial tire 10 (tire size 46 × 17R20) shown in the present embodiment (FIG. 1) was prototyped according to the specifications shown in Table 1, and the weight, the specified internal pressure, the specified load, and the speed were 40MP.
Table 1 shows the results of a test in which the vehicle was run at a steering angle of 4 degrees for 10 minutes and allowed to cool for 50 minutes using an indoor drum.

These experimental results show that the above-described pneumatic radial tire of the present invention is particularly excellent.

〔The invention's effect〕

The present invention has an excellent effect that the durability of the carcass of the side wall can be improved without an extreme increase in weight because of the above-mentioned configuration.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a pneumatic radial tire according to an embodiment of the present invention, which is cut along a plane including a rotating shaft and partially omitted hatching, and FIG. 2 is a side view of a carcass of the present embodiment. It is the expanded sectional view cut | disconnected in the perpendicular direction. 10 ... pneumatic radial tire, 12 ... carcass, 13 ... carcass cord, 14 ... down carcass, 15 ... coating rubber, 16 ... bead core, 20 ... side wall.

Claims (1)

(57) [Claims] An at least two or more inner up carcass layers and a plurality of outer down carcass layers comprising organic fiber cords coated with a coating rubber and oriented substantially at 90 ° to the tire circumferential direction. A pneumatic radial tire for an aircraft having a composite carcass layer formed and at least one or more belt layers radially outward of a crown portion of the composite carcass layer in a tire radial direction, wherein an outermost portion in a tire cross section including a tire rotation axis is provided. The length from the intersection P between the outermost carcass plane and the equatorial plane to the end of the belt layer along the carcass surface is LB, and the length from the intersection P between the outermost carcass plane and the equatorial plane along the outermost carcass surface. Is L, the distance between the cord and the cord between adjacent carcass plies measured perpendicular to the carcass surface and the cord is GM, and the cross-sectional diameter of the cord is
When DC is set, the relationship of GM / DC is L / LB ≦ 0.9, GM / DC <0.22 0.9 <L / LB ≦ 1.1, GM / DC> 0.20 L / LB> 1.1 A pneumatic radial tire, wherein GM / DC> 0.40.