WO2019124469A1 - Radial tire for aircraft - Google Patents

Radial tire for aircraft Download PDF

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Publication number
WO2019124469A1
WO2019124469A1 PCT/JP2018/046891 JP2018046891W WO2019124469A1 WO 2019124469 A1 WO2019124469 A1 WO 2019124469A1 JP 2018046891 W JP2018046891 W JP 2018046891W WO 2019124469 A1 WO2019124469 A1 WO 2019124469A1
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Prior art keywords
tire
plies
radial
cable
diameter
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PCT/JP2018/046891
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French (fr)
Japanese (ja)
Inventor
岳 小川
英昭 深川
一敬 ▲徳▼冨
松本　拓也
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株式会社ブリヂストン
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Publication of WO2019124469A1 publication Critical patent/WO2019124469A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C15/00—Tyre beads, e.g. ply turn-up or overlap
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C15/00—Tyre beads, e.g. ply turn-up or overlap
    • B60C15/04—Bead cores
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/02—Carcasses
    • B60C9/04—Carcasses the reinforcing cords of each carcass ply arranged in a substantially parallel relationship
    • B60C9/08—Carcasses the reinforcing cords of each carcass ply arranged in a substantially parallel relationship the cords extend transversely from bead to bead, i.e. radial ply

Definitions

  • the present invention relates to a radial tire for aircraft, and more particularly to a tire that reduces the occurrence of separation of bead portions.
  • tires Radial tires for aircraft (hereinafter also referred to as "tires") are used under heavy load conditions, and very high regulated internal pressure is determined by public standards, and in general, a plurality of plies made of organic fiber cords are laminated Reinforcement is used in the carcass.
  • the separation by the distortion of the rubber can be achieved by optimizing the thickness of the rubber at the back of the bead portion in relation to the rim. We prevent outbreak.
  • FIGS. 1A and 1B schematic cross-sectional views showing a bead portion of a conventional radial tire for aircraft are shown in FIGS. 1A and 1B.
  • FIG. 1A shows the bead before loading is applied to the tire
  • FIG. 1B shows the bead 300 directly under the tire loading, with loading applied to the tire.
  • the cable bead 200 and the radial carcass 400 are embedded in the bead portion 300 of any of the tires shown in FIGS. 1A and 1B.
  • the radial carcass 400 is shown by a single thick line in the figure but is composed of a plurality of laminated plies.
  • FIG. 1A what is shown in FIG. 1A is the state of the bead portion 300 before the load is applied in a state where the tire is assembled to the rim R and filled with the internal pressure. From this state, when a load is applied to the tire, as shown in FIG. 1B, the bead portion 300 directly under the tire load falls largely to the outer side in the tire width direction (arrow Y1). Then, the ply located at the outermost side of the tire among the plurality of laminated plies is compressed in the longitudinal direction (arrow Y2) of the ply cord. As a result, micro cracks are generated between the organic fiber cords constituting the ply and the rubber in contact therewith. Such micro cracks gradually develop along the cord and eventually become separation between the organic fiber cord and the rubber.
  • the inventor further investigated the means for avoiding the generation of the cracks based on the above-mentioned knowledge of the generation process of the back separation, and to suppress the generation of the micro cracks between the organic fiber cord and the rubber. They found that it was effective to apply a pulling force opposite to the compression in the longitudinal direction of the ply cord, and completed the present invention.
  • the gist of the present invention is as follows.
  • the radial tire for aircraft according to the present invention comprises at least two of a pair of annular cable beads and a ply formed by rubber coating a plurality of organic fiber cords extending in a toroidal shape between the cable beads. And at least one turn-up ply obtained by winding the ply from the inner side in the tire width direction of each cable bead to the outer side, and the ply at the winding portion of the turn-up ply.
  • the tire radial diameter B (mm mm) defined in an aircraft radial tire comprising: at least one downply extending to at least the tire radial direction inner side of the cable bead, covering the tire width direction outer side.
  • TRA means TIRE AND RIM ASSOCIATION, INC. Of the United States.
  • TRA AIR CRAFT YEAR BOOK or EDI (ENGINEERING DESIGN INFORMATION FOR AIR CRAFT TIRES) (the numerical values of the present invention use the 2017 version).
  • the "specified internal pressure” refers to the application size described in TRA, the air pressure corresponding to the specified load of a single wheel in ply rating.
  • “specified load” refers to the application size described in TRA, the maximum static load of single wheels in ply rating, and ply rating is an index indicating the strength of the tire.
  • tire nominal diameter” and “tire nominal width” are nominal dimensions described in TRA.
  • “cable bead” refers to a bead core of a cable bead structure.
  • the tire which can make the durability improvement of a bead part compatible with the weight reduction of a tire can be provided.
  • FIG. 2 shows a ply structure of an aircraft radial tire subjected to an experiment.
  • the radial tire 1 for an aircraft shown in FIG. 2 (hereinafter referred to as a tire 1) is rubber-coated with a pair of annular cable beads 2 and a plurality of organic fiber cords extending between the cable beads 2 in a toroidal shape.
  • the radial carcass 4 comprises at least two, seven in the illustrated example, of the radial direction plies, and the radial carcass 4 is one or more of the plies wound from the inner side in the tire width direction of each cable bead.
  • FIG. 2 shows five turn-up plies 5a to 5e and two down-plies 6a and 6b, the number is not limited to the number and may be any number.
  • the behavior of the bead part periphery at the time of filling an internal pressure into a tire is demonstrated using the tire 1 which has said structure.
  • the radial tire for aircraft is used by filling it with the standard internal pressure defined by the public standard as the maximum value.
  • the inventor rotates the cable bead 2 in the direction of the arrow Y4 as described above as the diameter A (hereinafter also referred to as the cable bead diameter A) in the cross-sectional view of the cable bead 2 including the tire rotation axis decreases. I also thought that the movement of would become bigger. On the other hand, if such rotational movement becomes too large, shear deformation in a stiffener between the ply and the cable bead may be excessive, leading to a decrease in durability.
  • the inventor of the present invention relieves the compressive force acting on the above-mentioned down ply 6b during the internal pressure filling without causing the above-mentioned problems, so that the durability of the bead portion is reduced.
  • the cable bead diameter A was determined in the range which can function as an anchor according to the specified load of the tire on the design of the tire.
  • the inventor has compared the ratio of the prescribed internal pressure D in accordance with the tire nominal diameter B, the tire nominal width C and the TRA with the square of the cable bead diameter A. Focusing on the relationship, the tire of various values is tested to measure the durability of the bead portion, and the ratio B ⁇ C ⁇ D / having durability of the bead portion higher than that of the conventional radial tire for aircraft is obtained.
  • the condition of A 2 was derived.
  • a tire of tire size 1 52 ⁇ 21.0R22 38 PR
  • tire size 2 (1400 ⁇ 530 R23 42 PR) which are suitable for comparison of tire performance
  • Table 1 The prototype was made based on the specifications, and the cable bead diameter A was changed variously to evaluate the separation durability of the back of the bead portion.
  • the evaluation was performed under the same conditions as in the examples described later, and the obtained evaluation results were organized as a graph, with the vertical axis representing the bead portion durability and the horizontal axis representing the ratio B ⁇ C ⁇ D / A 2 .
  • the arranged graph is shown in FIG.
  • the tire nominal diameter B (mm), the tire nominal width C (mm) and the prescribed internal pressure D (kPa), and the diameter A (mm) in a sectional view by a plane including the tire rotation axis of the cable bead It can be seen that, for a tire that satisfies 1940000 ⁇ B ⁇ C ⁇ D / A 2 in relation to the square, the bead portion durability is significantly improved and the separation durability of the back surface of the bead portion is improved. In the tire which does not satisfy the above numerical range, even if the ratio B ⁇ C ⁇ D / A 2 is changed, the effect of improving the bead portion durability can hardly be obtained.
  • the inventor uses a tire tire having a nominal diameter B (mm), a nominal tire width C (mm), a prescribed internal pressure D (kPa), and a plane including the tire rotation axis of the cable bead. That the relationship between the diameter A (mm) in the cross sectional view and the square of 1940000 ⁇ B ⁇ C ⁇ D / A 2 satisfy both durability improvement of the bead portion and weight reduction of the tire I found it.
  • the relationship between the tire nominal diameter B (mm), tire nominal width C (mm) and prescribed internal pressure D (kPa), and the square of the diameter A (mm) in a sectional view by a plane including the tire rotation axis of the cable bead Preferably satisfy B ⁇ C ⁇ D / A 2 ⁇ 3540000. According to this configuration, it is possible to prevent excessive shear deformation in the stiffener between the ply and the cable bead, and to avoid the decrease in durability.
  • the cable bead has a core made of steel formed in an annular shape, and a sheath made of at least one sheath layer in which a sheath filament made of steel is spirally wound around the core.
  • a bead can be used.
  • the carbon content of the sheath filament is preferably 0.90 to 0.95% by mass, and the chromium content is preferably 0.15 to 0.30% by mass. According to such a configuration, even in the case where the outer diameter of the cable bead is smaller than that of the prior art, the anchor function of the bead can be effectively maintained.
  • the weight of the cable bead is 100 (Comparative Example 1) when the cable bead diameter A is 25 mm in the tire size 1 and 100 (Comparative Example 3) when the cable bead diameter A is 27 mm in the tire size 2. The smaller the number, the lighter.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Tires In General (AREA)

Abstract

A radial tire for an aircraft, comprising a pair of annular cable beads, and a radial carcass that is configured from at least two plies extending in toroidal form between the cable beads and is obtained by covering a plurality of organic fiber cords with rubber, the radial carcass having one or more upturned plies in which the plies are rolled up from the inward (with respect to the tire width) sides of the cable beads to the outward sides, and one or more down plies of which the plies cover the outward (with respect to the tire width) sides of the rolled-up portions of the upturned plies and which extend at least to the inward (with respect to the tire radius) sides of the cable beads, wherein the radial tire for an aircraft is characterized in that the relationship 1940000 ≤ B×C×D/A2 holds between: the nominal diameter B (mm) of the tire, the nominal width C (mm) of the tire, and the specified internal pressure D (kPa), as established by the TRA; and the square of the diameter A (mm) of the cable beads in a cross-sectional view along a plane including the axis of tire rotation.

Description

航空機用ラジアルタイヤAircraft radial tire
　この発明は、航空機用ラジアルタイヤ、特に、ビード部のセパレーションの発生を低減するタイヤに関する。 The present invention relates to a radial tire for aircraft, and more particularly to a tire that reduces the occurrence of separation of bead portions.
　航空機用ラジアルタイヤ（以下、「タイヤ」ともいう）は、重荷重条件下で使用され、非常に高い規定内圧が公的規格により定められるとともに、一般に、有機繊維コードからなるプライを複数枚積層した補強材がカーカスに用いられている。 Radial tires for aircraft (hereinafter also referred to as "tires") are used under heavy load conditions, and very high regulated internal pressure is determined by public standards, and in general, a plurality of plies made of organic fiber cords are laminated Reinforcement is used in the carcass.
　このような航空機ラジアルタイヤでは、重荷重が加えられると、ビード部において、最もタイヤ幅方向外側に位置するプライとゴムの間に、セパレーション（以下、「背面セパレーション」という）が発生することがあった。 In such an aircraft radial tire, when heavy load is applied, separation (hereinafter referred to as “rear separation”) sometimes occurs in the bead portion between the ply located at the outermost side in the tire width direction and the rubber. The
　上記の背面セパレーションを低減するための方途として、特許文献１に記載の航空機用ラジアルタイヤでは、リムとの関係で、ビード部背面におけるゴムの厚みを適正化することにより、ゴムの歪みによるセパレーションの発生を防止している。 As a means for reducing the above-mentioned back separation, in the radial tire for an aircraft described in Patent Document 1, the separation by the distortion of the rubber can be achieved by optimizing the thickness of the rubber at the back of the bead portion in relation to the rim. We prevent outbreak.
特開２００６－１３１０９５号公報Unexamined-Japanese-Patent No. 2006-131095
　近年、環境保全や経済性の観点から、航空機の燃料消費を低減することが求められる中、航空機に装着するタイヤの軽量化への要求も厳しくなってきている。しかしながら、特許文献１に記載の、ゴムの厚みを適正化する手法では、必ずしも上記軽量化の要求を十分に満たすことができない場合があった。そこで、ビード部の耐久性向上と、軽量化とを両立し得るタイヤが希求されている。 In recent years, while it is required to reduce fuel consumption of an aircraft from the viewpoint of environmental protection and economy, the demand for weight reduction of tires mounted on the aircraft has also become severe. However, in the method of optimizing the thickness of rubber described in Patent Document 1, there were cases in which the above-mentioned demand for weight reduction could not be sufficiently satisfied. Therefore, there is a need for a tire that can achieve both improvement in durability of the bead portion and weight reduction.
　発明者は、前記課題を解決する手段について鋭意究明したところ、以下の知見を得た。該知見について説明するため、従来の航空機用ラジアルタイヤのビード部を示す概略断面図を、図１Ａ及び図１Ｂに示す。図１Ａは、タイヤに荷重が加えられる前のビード部を示しており、図１Ｂは、タイヤに荷重が加えられた状態での、タイヤ荷重直下のビード部３００を示している。なお、図１Ａ及び図１Ｂのいずれのタイヤのビード部３００も、ケーブルビード２００及びラジアルカーカス４００が埋設されている。ラジアルカーカス４００は、図示では１本の太線で示されるが、複数積層されたプライから構成されている。 The inventor has obtained the following findings as a result of intensive investigation on means for solving the above-mentioned problems. In order to explain the findings, schematic cross-sectional views showing a bead portion of a conventional radial tire for aircraft are shown in FIGS. 1A and 1B. FIG. 1A shows the bead before loading is applied to the tire, and FIG. 1B shows the bead 300 directly under the tire loading, with loading applied to the tire. The cable bead 200 and the radial carcass 400 are embedded in the bead portion 300 of any of the tires shown in FIGS. 1A and 1B. The radial carcass 400 is shown by a single thick line in the figure but is composed of a plurality of laminated plies.
　即ち、図１Ａに示されるのは、タイヤがリムＲに組み付けられ、内圧を充填された状態で、荷重を加えられる前の、ビード部３００の状態である。この状態から、タイヤに荷重が加えられると、図１Ｂに示すとおり、タイヤ荷重直下のビード部３００が、タイヤ幅方向外側に大きく倒れ込む（矢印Ｙ１）。すると、複数積層されたプライのうち、最もタイヤ外側に位置するプライは、プライコードの長手方向（矢印Ｙ２）に圧縮される。これにより、プライを構成する有機繊維コードと、これと接しているゴムとの間に微小な亀裂が発生する。このような微小な亀裂がコードに沿って徐々に進展し、やがては有機繊維コードとゴムとの間のセパレーションとなる。 That is, what is shown in FIG. 1A is the state of the bead portion 300 before the load is applied in a state where the tire is assembled to the rim R and filled with the internal pressure. From this state, when a load is applied to the tire, as shown in FIG. 1B, the bead portion 300 directly under the tire load falls largely to the outer side in the tire width direction (arrow Y1). Then, the ply located at the outermost side of the tire among the plurality of laminated plies is compressed in the longitudinal direction (arrow Y2) of the ply cord. As a result, micro cracks are generated between the organic fiber cords constituting the ply and the rubber in contact therewith. Such micro cracks gradually develop along the cord and eventually become separation between the organic fiber cord and the rubber.
　発明者は、さらに、上記の背面セパレーションの発生過程に関する知見に基づいて、この亀裂の発生を回避する手段について究明したところ、有機繊維コードとゴムとの間の微小な亀裂の発生を抑制するには、プライコードの長手方向に、圧縮とは逆の引っ張りの力を作用させることが有効であることを見出し、本発明を完成するに至った。 The inventor further investigated the means for avoiding the generation of the cracks based on the above-mentioned knowledge of the generation process of the back separation, and to suppress the generation of the micro cracks between the organic fiber cord and the rubber. They found that it was effective to apply a pulling force opposite to the compression in the longitudinal direction of the ply cord, and completed the present invention.
　本発明の要旨は、以下のとおりである。
　本発明の航空機用ラジアルタイヤは、一対の環状のケーブルビードと、これらケーブルビード間にトロイド状に延在する、複数本の有機繊維コードをゴム被覆してなるプライの少なくとも２枚にて構成したラジアルカーカスと、を備え、前記ラジアルカーカスは、前記プライを各前記ケーブルビードのタイヤ幅方向内側から外側へ巻上げた、１枚以上のターンアッププライと、前記プライを前記ターンアッププライの巻上げ部分のタイヤ幅方向外側を覆って、少なくとも前記ケーブルビードのタイヤ径方向内側まで延ばした、１枚以上のダウンプライと、を有してなる航空機用ラジアルタイヤにおいて、ＴＲＡに定める、タイヤ呼び径Ｂ（ｍｍ）、タイヤ呼び幅Ｃ（ｍｍ）及び規定内圧Ｄ（ｋＰａ）と、前記ケーブルビードのタイヤ回転軸を含む平面による断面視における径Ａ（ｍｍ）の2乗との関係は、1940000≦Ｂ×Ｃ×Ｄ／Ａ2を満たすことを特徴とする。
　ここで、ＴＲＡとは、米国のＴＩＲＥ　ＡＮＤ　ＲＩＭ　ＡＳＳＯＣＩＡＴＩＯＮ，ＩＮＣ．）が発行する、最新版のＡＩＲＣＲＡＦＴ　ＹＥＡＲ　ＢＯＯＫあるいはＥＤＩ（ＥＮＧＩＮＥＥＲＩＮＧ　ＤＥＳＩＧＮ　ＩＮＦＯＲＭＡＴＩＯＮ　ＦＯＲ　ＡＩＲＣＲＡＦＴ　ＴＩＲＥＳ）（本発明の数値の記載は２０１７年度版を使用）に定められた規格を意味する。「規定内圧」とは、ＴＲＡに記載されている適用サイズ、プライレーティングにおける単輪の規定荷重に対応する空気圧を指す。さらに、「規定荷重」とは、ＴＲＡに記載されている適用サイズ、プライレーティングにおける単輪の最大静荷重を指し、また、プライレーティングとは、タイヤの強度を示す指数である。また、「タイヤ呼び径」及び「タイヤ呼び幅」とは、ＴＲＡで記載している呼び寸法のことである。
　なお、本発明における「ケーブルビード」とは、ケーブルビード構造のビードコアを指す。 The gist of the present invention is as follows.
The radial tire for aircraft according to the present invention comprises at least two of a pair of annular cable beads and a ply formed by rubber coating a plurality of organic fiber cords extending in a toroidal shape between the cable beads. And at least one turn-up ply obtained by winding the ply from the inner side in the tire width direction of each cable bead to the outer side, and the ply at the winding portion of the turn-up ply. In the radial tire for an aircraft, the tire radial diameter B (mm mm) defined in an aircraft radial tire comprising: at least one downply extending to at least the tire radial direction inner side of the cable bead, covering the tire width direction outer side. Tire nominal width C (mm) and prescribed internal pressure D (kPa), and the tire rotation axis of the cable bead Relationship between the square of the diameter A (mm) in the cross section by no plane, and satisfies the 1940000 ≦ B × C × D / A 2.
Here, TRA means TIRE AND RIM ASSOCIATION, INC. Of the United States. Means the standard defined in the latest version of AIR CRAFT YEAR BOOK or EDI (ENGINEERING DESIGN INFORMATION FOR AIR CRAFT TIRES) (the numerical values of the present invention use the 2017 version). The "specified internal pressure" refers to the application size described in TRA, the air pressure corresponding to the specified load of a single wheel in ply rating. Furthermore, “specified load” refers to the application size described in TRA, the maximum static load of single wheels in ply rating, and ply rating is an index indicating the strength of the tire. Moreover, "tire nominal diameter" and "tire nominal width" are nominal dimensions described in TRA.
In the present invention, “cable bead” refers to a bead core of a cable bead structure.
　本発明により、ビード部の耐久性向上と、タイヤの軽量化とを両立し得るタイヤを提供することができる。 ADVANTAGE OF THE INVENTION By this invention, the tire which can make the durability improvement of a bead part compatible with the weight reduction of a tire can be provided.
従来の航空機用ラジアルタイヤのビード部を示す概略断面図である。It is a schematic sectional drawing which shows the bead part of the conventional radial tire for aircrafts. 従来の航空機用ラジアルタイヤのビード部を示す概略断面図である。It is a schematic sectional drawing which shows the bead part of the conventional radial tire for aircrafts. 実験に供した航空機用ラジアルタイヤのプライ構造を示す図である。It is a figure which shows the ply structure of the radial tire for aircrafts provided to the experiment. 実験結果を示すグラフである。It is a graph which shows an experimental result.
　以下、本発明の航空機用ラジアルタイヤを導くに至った実験結果について説明する。
　まず、図２に、実験に供した航空機用ラジアルタイヤのプライ構造を示す。図２の航空機用ラジアルタイヤ１（以下、タイヤ１という）は、一対の環状のケーブルビード２と、これらケーブルビード２間にトロイド状に延在する、複数本の有機繊維コードをゴム被覆してなるラジアル方向プライの少なくとも２枚、図示例では７枚にて構成したラジアルカーカス４と、を備え、ラジアルカーカス４は、プライを各ケーブルビードのタイヤ幅方向内側から外側へ巻上げた、１枚以上のターンアッププライ５ａ～５ｅと、プライをターンアッププライ５ｅの巻上げ部分のタイヤ幅方向外側を覆って、少なくとも前記ケーブルビードのタイヤ径方向内側まで延ばした、１枚以上のダウンプライ６ａ及び６ｂと、を有している。なお、図２では、５枚のターンアッププライ５ａ～５ｅと、２枚のダウンプライ６ａ及び６ｂとが示されるが、この枚数に限られず、任意の枚数にて構成することができる。 Hereinafter, the experimental result which led to the radial tire for aircraft of this invention is demonstrated.
First, FIG. 2 shows a ply structure of an aircraft radial tire subjected to an experiment. The radial tire 1 for an aircraft shown in FIG. 2 (hereinafter referred to as a tire 1) is rubber-coated with a pair of annular cable beads 2 and a plurality of organic fiber cords extending between the cable beads 2 in a toroidal shape. The radial carcass 4 comprises at least two, seven in the illustrated example, of the radial direction plies, and the radial carcass 4 is one or more of the plies wound from the inner side in the tire width direction of each cable bead. Turnup plies 5a to 5e, and one or more downplies 6a and 6b, which cover the outer side of the winding portion of the turnup ply 5e in the tire width direction and extend at least to the inner side in the radial direction of the cable bead ,have. Although FIG. 2 shows five turn-up plies 5a to 5e and two down- plies 6a and 6b, the number is not limited to the number and may be any number.
　上記の構造を有するタイヤ１を用いて、タイヤに内圧を充填した際の、ビード部周辺の挙動について説明する。
　ここで、航空機用ラジアルタイヤは、公的規格により定められる、規格内圧を最大値として充填して使用に供される。 The behavior of the bead part periphery at the time of filling an internal pressure into a tire is demonstrated using the tire 1 which has said structure.
Here, the radial tire for aircraft is used by filling it with the standard internal pressure defined by the public standard as the maximum value.
　タイヤ１に、内圧が充填されると、タイヤのトレッドの径成長に伴い、ターンアッププライ５ａ～５ｅ及びターンアッププライ５ａ～５ｅと接しているゴムが、トレッド側に向かって引き上げられる（図２の矢印Ｙ３方向）。このようなターンアッププライ５ａ～５ｅ及び周囲のゴムの引き上げ動作によって、ケーブルビード２は、回転する方向（図２の矢印Ｙ４方向）へ動く。さらに、ターンアッププライ５ａ～５ｅの引き上げとケーブルビード２の回転とによって、周囲のゴムと一緒に、内圧充填で元々引っ張られているダウンプライ６ａ及び６ｂはさらに引っ張られ、Ｙ３方向に動く。発明者は、このような引っ張りの力がダウンプライ６ｂに作用すると、上述の荷重付加時におけるダウンプライ６ｂの圧縮が緩和されることを新たに知見した。 When the tire 1 is filled with internal pressure, the rubber in contact with the turnup plies 5a to 5e and the turnup plies 5a to 5e is pulled up toward the tread side as the diameter of the tread of the tire grows (FIG. 2) Arrow Y3 direction). The cable bead 2 is moved in the rotating direction (the direction of the arrow Y4 in FIG. 2) by the pulling up operation of the turn-up plies 5a to 5e and the surrounding rubber. Further, the pulling up of the turnup plies 5a to 5e and the rotation of the cable bead 2 further pull the downplies 6a and 6b originally pulled by the internal pressure filling together with the surrounding rubber, and move in the Y3 direction. The inventor has newly found that when such a pulling force acts on the downply 6b, the compression of the downply 6b at the time of loading described above is relieved.
　さらに、発明者は、ケーブルビード２のタイヤ回転軸を含む平面による断面視における径Ａ（以下、ケーブルビード径Ａともいう）を小さくする程、上述の、ケーブルビード２の矢印Ｙ４方向への回転の動きが、より大きくなることにも想到した。一方、このような回転の動きが大きくなり過ぎると、プライとケーブルビードとの間にあるスティフナーにおけるせん断変形が過剰となり、耐久性の低下につながる虞がある。 Furthermore, the inventor rotates the cable bead 2 in the direction of the arrow Y4 as described above as the diameter A (hereinafter also referred to as the cable bead diameter A) in the cross-sectional view of the cable bead 2 including the tire rotation axis decreases. I also thought that the movement of would become bigger. On the other hand, if such rotational movement becomes too large, shear deformation in a stiffener between the ply and the cable bead may be excessive, leading to a decrease in durability.
　そこで、発明者は、上記のような問題を発生させることなく、内圧充填時に、ダウンプライ６ｂに作用する引っ張り力が、上述のダウンプライ６ｂに作用する圧縮力を緩和し、ビード部の耐久性を著しく向上させるための要件について、さらに究明するため、種々の実験を行った。すると、上記要件には、タイヤ呼び径Ｂ、タイヤ呼び幅Ｃ、及びＴＲＡに従う規定内圧Ｄと、ケーブルビード径Ａの２乗との関係、すなわち、ケーブルビード単位面積辺りの張力の指標が密接に関連することを新たに知見した。 Therefore, the inventor of the present invention relieves the compressive force acting on the above-mentioned down ply 6b during the internal pressure filling without causing the above-mentioned problems, so that the durability of the bead portion is reduced. Various experiments were conducted to further investigate the requirements for significantly improving Then, the above requirements closely indicate the relationship between the prescribed internal pressure D according to the tire nominal diameter B, tire nominal width C and TRA, and the square of the cable bead diameter A, that is, the index of tension per cable bead unit area I discovered new things related to it.
　即ち、ケーブルビード径Ａは、タイヤの設計上、当該タイヤの規定荷重に応じて、アンカーとして機能し得る範囲に定められていた。しかしながら、発明者は、最外側のカーカスプライに作用する力の向きの観点から、タイヤ呼び径Ｂ、タイヤ呼び幅Ｃ及びＴＲＡに従う規定内圧Ｄと、ケーブルビード径Ａの２乗との比との関係に着目し、様々な値のタイヤに対して、ビード部の耐久性を計測する試験を行い、従来の航空機用ラジアルタイヤよりも高いビード部の耐久性を有する、比Ｂ×Ｃ×Ｄ／Ａ２の条件を導出した。 That is, the cable bead diameter A was determined in the range which can function as an anchor according to the specified load of the tire on the design of the tire. However, from the viewpoint of the direction of the force acting on the outermost carcass ply, the inventor has compared the ratio of the prescribed internal pressure D in accordance with the tire nominal diameter B, the tire nominal width C and the TRA with the square of the cable bead diameter A. Focusing on the relationship, the tire of various values is tested to measure the durability of the bead portion, and the ratio B × C × D / having durability of the bead portion higher than that of the conventional radial tire for aircraft is obtained. The condition of A 2 was derived.
　以下、ビード部の耐久性の向上に、タイヤ呼び径Ｂ、タイヤ呼び幅Ｃ及び規定内圧Ｄと、ケーブルビード径Ａの2乗との比が関連することを導出するに至った実験結果について、詳しく説明する。 Hereinafter, about the experimental result which came to derive that the ratio of the tire nominal diameter B, the tire nominal width C and the prescribed internal pressure D, and the square of the cable bead diameter A is related to the improvement of the durability of the bead portion. explain in detail.
　まず、評価基準となるタイヤとして、タイヤ性能の比較に適している、タイヤサイズ１（５２×２１．０Ｒ２２　３８ＰＲ）及びタイヤサイズ２（１４００×５３０Ｒ２３　４２ＰＲ）のタイヤを作製して、表１に示す仕様に基づいて試作し、ケーブルビード径Ａを多様に変化させて、ビード部背面のセパレーション耐久性を各々評価した。
　評価は、後述する実施例と同様の条件にて行い、得られた評価結果を、縦軸をビード部耐久性とし、横軸を比Ｂ×Ｃ×Ｄ／Ａ2とする、グラフとして整理した。整理したグラフを、図３に示す。 First, a tire of tire size 1 (52 × 21.0R22 38 PR) and tire size 2 (1400 × 530 R23 42 PR), which are suitable for comparison of tire performance, is manufactured as a evaluation standard and shown in Table 1 The prototype was made based on the specifications, and the cable bead diameter A was changed variously to evaluate the separation durability of the back of the bead portion.
The evaluation was performed under the same conditions as in the examples described later, and the obtained evaluation results were organized as a graph, with the vertical axis representing the bead portion durability and the horizontal axis representing the ratio B × C × D / A 2 . The arranged graph is shown in FIG.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　図３に示すように、タイヤ呼び径Ｂ（ｍｍ）、タイヤ呼び幅Ｃ（ｍｍ）及び規定内圧Ｄ（ｋＰａ）と、ケーブルビードのタイヤ回転軸を含む平面による断面視における径Ａ（ｍｍ）の2乗との関係が、1940000≦Ｂ×Ｃ×Ｄ／Ａ2を満たすタイヤについては、ビード部耐久性が著しく向上し、ビード部背面のセパレーション耐久性が向上することがわかる。なお、上記数値範囲を満たさないタイヤでは、比Ｂ×Ｃ×Ｄ／Ａ2を変化させても、ビード部耐久性の向上効果はほとんど得られない。
　発明者は、斯くの如くして、航空機用ラジアルタイヤにおいて、タイヤ呼び径Ｂ（ｍｍ）、タイヤ呼び幅Ｃ（ｍｍ）及び規定内圧Ｄ（ｋＰａ）と、ケーブルビードのタイヤ回転軸を含む平面による断面視における径Ａ（ｍｍ）の2乗との関係が、1940000≦Ｂ×Ｃ×Ｄ／Ａ2を満たすことで、ビード部の耐久性向上と、タイヤの軽量化とを両立し得ることを見出したものである。 As shown in FIG. 3, the tire nominal diameter B (mm), the tire nominal width C (mm) and the prescribed internal pressure D (kPa), and the diameter A (mm) in a sectional view by a plane including the tire rotation axis of the cable bead It can be seen that, for a tire that satisfies 1940000 ≦ B × C × D / A 2 in relation to the square, the bead portion durability is significantly improved and the separation durability of the back surface of the bead portion is improved. In the tire which does not satisfy the above numerical range, even if the ratio B × C × D / A 2 is changed, the effect of improving the bead portion durability can hardly be obtained.
In the radial tire for an aircraft, the inventor thus uses a tire tire having a nominal diameter B (mm), a nominal tire width C (mm), a prescribed internal pressure D (kPa), and a plane including the tire rotation axis of the cable bead. That the relationship between the diameter A (mm) in the cross sectional view and the square of 1940000 ≦ B × C × D / A 2 satisfy both durability improvement of the bead portion and weight reduction of the tire I found it.
　また、タイヤ呼び径Ｂ（ｍｍ）、タイヤ呼び幅Ｃ（ｍｍ）及び規定内圧Ｄ（ｋＰａ）と、ケーブルビードのタイヤ回転軸を含む平面による断面視における径Ａ（ｍｍ）の2乗との関係は、Ｂ×Ｃ×Ｄ／Ａ2≦3540000を満たすことが好ましい。この構成によれば、プライとケーブルビードとの間にあるスティフナーにおけるせん断変形が過剰となるのを防止して、耐久性の低下を避けることができる。 In addition, the relationship between the tire nominal diameter B (mm), tire nominal width C (mm) and prescribed internal pressure D (kPa), and the square of the diameter A (mm) in a sectional view by a plane including the tire rotation axis of the cable bead Preferably satisfy B × C × D / A 2 ≦ 3540000. According to this configuration, it is possible to prevent excessive shear deformation in the stiffener between the ply and the cable bead, and to avoid the decrease in durability.
　なお、より好適な数値範囲としては、Ｂ×Ｃ×Ｄ/Ａ２≧２１５００００であることがより好ましい。 A more suitable range, and more preferably B × C × D / A 2 ≧ 2150000.
　また、本発明の航空機用ラジアルタイヤにおいては、ベルトの剛性を上げたり、ケーブルビードの強度を上げた素材を使用したりすることが好ましい。例えば、本ケーブルビードは、環状に形成されたスチールからなるコアと、該コアの周りにスチールからなるシースフィラメントが螺旋状に巻き付けられてなる、少なくとも１層のシース層からなるシースとを有するケーブルビードを使用することができる。さらに、シースフィラメントの炭素含有量は、０．９０～０．９５質量％であり、かつ、クロム含有量は、０．１５～０．３０質量％であることが好適である。このような構成によれば、ケーブルビードの外径を従来よりも小さくした場合においても、ビードのアンカー機能を効果的に維持することができる。 Further, in the radial tire for aircraft according to the present invention, it is preferable to increase the rigidity of the belt or to use a material in which the strength of the cable bead is increased. For example, the cable bead has a core made of steel formed in an annular shape, and a sheath made of at least one sheath layer in which a sheath filament made of steel is spirally wound around the core. A bead can be used. Furthermore, the carbon content of the sheath filament is preferably 0.90 to 0.95% by mass, and the chromium content is preferably 0.15 to 0.30% by mass. According to such a configuration, even in the case where the outer diameter of the cable bead is smaller than that of the prior art, the anchor function of the bead can be effectively maintained.
　上記表１に示す仕様の、タイヤサイズ１及びタイヤサイズ２のタイヤを用いて、表２に示す諸元のもと、各比較例及び発明例に係るタイヤについて、ビード部背面のセパレーション耐久性を各々評価した。
具体的には、タイヤをリムに組み付けたリム組立体を、ドラム上で所定の負荷をかけて、６４ｋｍ／ｈの速度で１０分間繰り返し回し、背面セパレーションが生じるまでのドラム試験での繰り返し回数により評価した。その結果を表２に示す。
　結果は、タイヤサイズ１のタイヤについては、比較例１のタイヤのセパレーション耐久性を１００とし、タイヤサイズ２のタイヤについては、比較例３のタイヤのセパレーション耐久性を１００として、タイヤサイズ毎に指数表示した。指数値が大きいほど、ビード部背面のセパレーション耐久性に優れることを示している。また、ケーブルビードの重量は、タイヤサイズ１においてはケーブルビード径Ａが２５ｍｍの時を１００（比較例１）、タイヤサイズ２においてはケーブルビード径Ａが２７ｍｍの時を１００（比較例３）とし、数値が小さいほど軽いことを示す。 Using the tires of tire size 1 and tire size 2 of the specifications shown in Table 1 above, under the specifications shown in Table 2, the separation durability of the back of the bead portion of the tire according to each comparative example and invention example Each was evaluated.
Specifically, the rim assembly in which the tire is assembled to the rim is repeatedly rotated for 10 minutes at a speed of 64 km / h under a predetermined load on the drum, and the number of repetitions in the drum test until rear separation occurs evaluated. The results are shown in Table 2.
The result is that the separation durability of the tire of Comparative Example 1 is 100 for the tire of tire size 1 and the separation durability of the tire of comparative example 3 is 100 for the tire of tire size 2 and the index for each tire size displayed. The larger the index value, the better the separation durability of the back of the bead portion. The weight of the cable bead is 100 (Comparative Example 1) when the cable bead diameter A is 25 mm in the tire size 1 and 100 (Comparative Example 3) when the cable bead diameter A is 27 mm in the tire size 2. The smaller the number, the lighter.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
１：タイヤ、　２、２００：ケーブルビード、　３００：ビード部、　４、４００：ラジアルカーカス、　５ａ、５ｂ、５ｃ、５ｄ、５ｅ：ターンアッププライ、　６ａ、６ｂ：ダウンプライ、　Ｒ：リム 1: Tire 2, 200: Cable bead, 300: Bead portion 4, 400: Radial carcass, 5a, 5b, 5c, 5d, 5e: Turn-up ply, 6a, 6b: Down ply, R: Rim

Claims (2)

  1. 　一対の環状のケーブルビードと、これらケーブルビード間にトロイド状に延在する、複数本の有機繊維コードをゴム被覆してなるプライの少なくとも２枚にて構成したラジアルカーカスと、を備え、
    　前記ラジアルカーカスは、前記プライを各前記ケーブルビードのタイヤ幅方向内側から外側へ巻上げた、１枚以上のターンアッププライと、前記プライを前記ターンアッププライの巻上げ部分のタイヤ幅方向外側を覆って、少なくとも前記ケーブルビードのタイヤ径方向内側まで延ばした、１枚以上のダウンプライと、を有してなる航空機用ラジアルタイヤにおいて、
    　ＴＲＡに定める、タイヤ呼び径Ｂ（ｍｍ）、タイヤ呼び幅Ｃ（ｍｍ）及び規定内圧Ｄ（ｋＰａ）と、
    　前記ケーブルビードのタイヤ回転軸を含む平面による断面視における径Ａ（ｍｍ）の2乗との関係は、
    　1940000≦Ｂ×Ｃ×Ｄ／Ａ2
    を満たすことを特徴とする航空機用ラジアルタイヤ。     A pair of annular cable beads, and a radial carcass consisting of at least two plies of rubber-coated plural organic fiber cords extending in a toroidal shape between the cable beads;
    The radial carcass covers one or more turn-up plies in which the plies are wound outward from the inner side in the tire width direction of each cable bead, and covers the outer sides of the turn-up plies in the tire width direction of the turn-up ply. An aircraft radial tire comprising at least one down ply extended at least to the tire radial direction of the cable bead;
    The tire nominal diameter B (mm), the tire nominal width C (mm), and the specified internal pressure D (kPa) as defined in TRA,
    The relationship between the diameter of the cable bead and the square of the diameter A (mm) in a cross-sectional view by a plane including the tire rotation axis is as follows:
    1940000 ≦ B × C × D / A 2
    An aircraft radial tire characterized by satisfying.
  2. 　前記タイヤ呼び径Ｂ（ｍｍ）、前記タイヤ呼び幅Ｃ（ｍｍ）及び前記規定内圧Ｄ（ｋＰａ）と、前記ケーブルビードのタイヤ回転軸を含む平面による断面視における径Ａ（ｍｍ）の2乗との関係は、
    　Ｂ×Ｃ×Ｄ／Ａ2≦3540000
    を満たす、請求項１に記載の航空機用ラジアルタイヤ。     The tire nominal diameter B (mm), the tire nominal width C (mm), the prescribed internal pressure D (kPa), and the square of the diameter A (mm) in a sectional view by a plane including the tire rotation axis of the cable bead The relationship is
    B × C × D / A 2 ≦ 3540000
    The radial tire for aircraft according to claim 1, wherein
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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08156533A (en) * 1994-11-30 1996-06-18 Sumitomo Rubber Ind Ltd Radial tire for high speed heavy road
JP2000071724A (en) * 1998-09-02 2000-03-07 Bridgestone Corp Pneumatic tire
JP2004010042A (en) * 2002-06-07 2004-01-15 Goodyear Tire & Rubber Co:The Lightweight cable bead core
JP2005212760A (en) * 2004-02-02 2005-08-11 Bridgestone Corp Radial tire for aircraft
JP2009298342A (en) * 2008-06-16 2009-12-24 Yokohama Rubber Co Ltd:The Radial tire for aircraft
JP2011509879A (en) * 2008-01-24 2011-03-31 ソシエテ ド テクノロジー ミシュラン Carcass reinforcement for aircraft tires
JP2014180896A (en) * 2013-03-18 2014-09-29 Bridgestone Corp Radial tire for aircraft
JP2015523475A (en) * 2012-06-07 2015-08-13 コンパニー ゼネラール デ エタブリッスマン ミシュラン Lighter hybrid bead wire for tires

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08156533A (en) * 1994-11-30 1996-06-18 Sumitomo Rubber Ind Ltd Radial tire for high speed heavy road
JP2000071724A (en) * 1998-09-02 2000-03-07 Bridgestone Corp Pneumatic tire
JP2004010042A (en) * 2002-06-07 2004-01-15 Goodyear Tire & Rubber Co:The Lightweight cable bead core
JP2005212760A (en) * 2004-02-02 2005-08-11 Bridgestone Corp Radial tire for aircraft
JP2011509879A (en) * 2008-01-24 2011-03-31 ソシエテ ド テクノロジー ミシュラン Carcass reinforcement for aircraft tires
JP2009298342A (en) * 2008-06-16 2009-12-24 Yokohama Rubber Co Ltd:The Radial tire for aircraft
JP2015523475A (en) * 2012-06-07 2015-08-13 コンパニー ゼネラール デ エタブリッスマン ミシュラン Lighter hybrid bead wire for tires
JP2014180896A (en) * 2013-03-18 2014-09-29 Bridgestone Corp Radial tire for aircraft

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