JPH1024712A - Pneumatic radial tireforheavy load - Google Patents
Pneumatic radial tireforheavy loadInfo
- Publication number
- JPH1024712A JPH1024712A JP8179120A JP17912096A JPH1024712A JP H1024712 A JPH1024712 A JP H1024712A JP 8179120 A JP8179120 A JP 8179120A JP 17912096 A JP17912096 A JP 17912096A JP H1024712 A JPH1024712 A JP H1024712A
- Authority
- JP
- Japan
- Prior art keywords
- tire
- rubber layer
- carcass ply
- bead
- hard rubber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Tires In General (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】この発明は、トラック、バ
ス、産業車両や建設車両などの重車両の使途に供する重
荷重用空気入りラジアルタイヤに関し、特にタイヤビー
ド部の重量増加を伴うことなくビード部耐久性を向上さ
せた重荷重用空気入りラジアルタイヤに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy-duty pneumatic radial tire for use in heavy vehicles such as trucks, buses, industrial vehicles and construction vehicles, and more particularly to a tire having a bead durability without increasing the weight of the tire bead. The present invention relates to a pneumatic radial tire for heavy loads with improved performance.
【０００２】[0002]
【従来の技術】重車両に用いる重荷重用空気入りラジア
ルタイヤは負荷転動中ビード部に作用する力が大きいた
め、ビード部故障、主としてセパレーション故障が発生
し勝ちであり、そのためこれまで耐セパレーション性を
主とする各種のビード部耐久性向上手段が提案されてい
て、それらのうちナイロンチェーファやワイヤーチェー
ファなどの補強部材の追加配置によるビード部剛性の一
層の向上や、カーカスラインの適正化による剛性配置の
修正などが良く知られている。2. Description of the Related Art A heavy-duty pneumatic radial tire used for heavy vehicles has a large force acting on the bead portion during rolling, so that a bead failure, mainly a separation failure, tends to occur. Various types of bead durability improvement means have been proposed, of which the bead rigidity is further improved by adding additional reinforcing members such as nylon chafers and wire chafers, and the carcass line is optimized. Modification of the rigid arrangement is well known.
【０００３】これら改善手段は内圧充填時、荷重負荷時
のサイドウォール部からビード部に至る間の部分の撓曲
変形、いわゆる倒れ込み変形の抑制、タイヤ転動時のビ
ード部における踏み込み部、蹴り出し部に発生する円周
方向剪断変形の抑制に有効であり、この種の変形抑制手
段はビード部耐久性向上に寄与するため広く採用されて
いる。[0003] These improvement means are to suppress bending deformation of a portion from the side wall portion to the bead portion at the time of internal pressure filling and load application, to suppress so-called collapse deformation, to step on the bead portion at the time of rolling the tire, to kick out. This is effective in suppressing circumferential shearing deformation generated in the portion, and this kind of deformation suppressing means is widely used because it contributes to improving the durability of the bead portion.
【０００４】[0004]
【発明が解決しようとする課題】しかし上記補強部材の
追加配置は当然重量増加をもたらす上、材料費用及び製
造工数の増加によるコストアップを招き、現状の厳しい
価格競争時代にそぐわない。またカーカスラインの修正
など重量増加によらない手段の適用は、確かに比較的マ
イルドな使用条件下で所期の効果を発揮する反面、使用
条件が益々酷しくなる現状に適応することはできず、所
期のビード部耐久性発揮に不十分であることが分かっ
た。However, the additional disposition of the reinforcing member naturally increases the weight and increases the cost due to the increase in the material cost and the number of manufacturing steps, which is not suitable for the current severe price competition era. In addition, the application of means that does not depend on weight increase, such as carcass line modification, certainly exerts the intended effect under relatively mild use conditions, but it can not adapt to the current situation where the use conditions are becoming increasingly severe It was found that the desired bead portion durability was insufficient.
【０００５】重車両用タイヤのなかでも特に大型建設車
両用空気入りラジアルタイヤではサイドウォール部の耐
カット性向上のためカーカス折返し部の高さを他の種類
のタイヤ対比大幅に高く設定し、時にタイヤ断面幅（最
大幅）位置前後の高さに設定するいわゆるハイターンア
ップ構造を採用するのが一般であり、そのため折返し端
部のセパレーション故障改善を主たる対象とする従来手
段は何れも有効な改善手段とはなり難い。なぜならタイ
ヤ転動中最も大きな歪が作用するのはリムのフランジ高
さ近傍位置であり、しかも上記大型タイヤは負荷時の撓
み率が他の種のタイヤ対比著しく大きいからである。[0005] Among heavy vehicle tires, in particular, in the case of pneumatic radial tires for large construction vehicles, the height of the carcass folded portion is set to be much higher than that of other types of tires in order to improve the cut resistance of the sidewall portion. In general, a so-called high-turn-up structure is used, which is set at a height before and after the tire cross-sectional width (maximum width) position. Therefore, any conventional means mainly aimed at improving the separation failure at the folded end is an effective improvement. It is hard to be a means. This is because the largest strain acts on the rim near the flange height during the rolling of the tire, and the large tire has a significantly higher deflection rate under load than other types of tires.
【０００６】上記大型タイヤの場合は特に、上述したよ
うに大きな撓み率により負荷転動時にリムのフランジと
接触する領域に存在する、折返し端から程遠い折返し途
中部分のプライに沿いセパレーション故障（ビード部故
障）が発生するのが特異な点である。よってこの大型タ
イヤの特異な故障に対し先に述べた従来の改善手段も含
めた従来手段は何れも市場要求を満たすビード部耐久性
発揮の決め手とならないのも止むを得ない。In the case of the above-mentioned large tire, the separation failure (bead portion) along the ply in the middle of the turn, which is far from the turn end, exists in the area which comes into contact with the flange of the rim when the load rolls due to the large bending rate as described above. The failure is a unique point. Therefore, it is unavoidable that any of the conventional means including the above-described conventional improvement means for the peculiar failure of the large tire does not become a decisive factor in exhibiting the durability of the bead portion satisfying the market requirements.
【０００７】従ってこの発明の目的は、タイヤ重量の増
加やコスト上昇を伴うことなく、カーカスラインの適正
化などでは対応できない程の過酷な使用条件の下でも十
分なビード部耐久性を発揮し得る重荷重用空気入りラジ
アルタイヤを提供することにある。Accordingly, an object of the present invention is to be able to exhibit sufficient bead portion durability under severe operating conditions which cannot be met by proper carcass lines without increasing tire weight or cost. An object of the present invention is to provide a pneumatic radial tire for heavy loads.
【０００８】[0008]
【課題を解決するための手段】上記目的を達成するた
め、この発明による重荷重用空気入りラジアルタイヤ
は、一対のビード部及び一対のサイドウォール部と、ト
レッド部とからなり、これら各部をビード部内に埋設し
たビードコア相互間にわたり補強するラジアル配列コー
ドのゴム被覆になるカーカスプライと、該カーカスプラ
イの外周に配置したベルトとを備え、カーカスプライは
ビードコア周りを巻上げた折返し部を有する重荷重用空
気入りラジアルタイヤにおいて、上記タイヤの正規内圧
を該タイヤとその適用リムとの組立体に充填して正規荷
重を負荷し解放したときの組立体断面に関し、荷重負荷
時におけるビード部表面のリムのフランジとの接触終端
位置を通るカーカスプライからの法線と、タイヤ断面幅
位置を通る直線との間に挟まれる領域内に、カーカスプ
ライ折返し部の外側表面に沿ってカーカスプライコード
の被覆ゴムより高い硬度をもつ硬質ゴム層を配置する一
方、該硬質ゴム層のタイヤ半径方向内側面に接合させる
と共に同上折返し部の外側表面に沿わせて上記被覆ゴム
より低い硬度をもつ軟質ゴム層を配置して成ることを特
徴とする。In order to achieve the above object, a heavy duty pneumatic radial tire according to the present invention comprises a pair of beads, a pair of sidewalls, and a tread. A carcass ply that serves as a rubber coating for a radially arranged cord that reinforces between the bead cores embedded in the carcass ply, and a belt disposed on the outer periphery of the carcass ply, wherein the carcass ply has a folded portion wound around the bead core and is filled with heavy load air. In a radial tire, the normal internal pressure of the tire is filled into an assembly of the tire and its applicable rim, and a normal load is applied and released. Between the normal line from the carcass ply passing through the contact end position of the A hard rubber layer having a higher hardness than the covering rubber of the carcass ply cord is arranged along the outer surface of the carcass ply turn-back portion in the region to be sandwiched, while being joined to the tire radial inner surface of the hard rubber layer and the same as above. A soft rubber layer having a hardness lower than that of the coated rubber is disposed along the outer surface of the folded portion.
【０００９】[0009]
【発明の実施の形態】この発明による重荷重用空気入り
ラジアルタイヤ（以下タイヤ又はラジアルタイヤとい
う）を一実施例に基づき以下詳細に説明する。図１は、
この発明による一実施例タイヤ２０を適用リム１０(JAT
MA YEAR BOOKに記載されたタイヤサイズに対応する適用
リム）に組込んだ組立体の線図的要部断面図であり、い
ずれのタイヤ２０も上記YEAR BOOK に記載した最高空気
圧（以下正規内圧と記す）を充填したときの、タイヤ断
面幅（最大幅）部分の図示を省略したビード部〜サイド
ウォール部内側部分の左側断面図である。BEST MODE FOR CARRYING OUT THE INVENTION A pneumatic radial tire for heavy loads (hereinafter referred to as a tire or a radial tire) according to the present invention will be described in detail based on an embodiment. FIG.
A tire 20 according to an embodiment of the present invention is applied to a rim 10 (JAT
FIG. 3 is a schematic cross-sectional view of a main part of an assembly incorporated in a tire size described in the MA YEAR BOOK). Each tire 20 has a maximum air pressure (hereinafter referred to as a normal internal pressure) FIG. 4 is a left side sectional view of a bead portion to an inner portion of a sidewall portion in which a tire sectional width (maximum width) portion is not illustrated when filling is performed.
【００１０】図１において、タイヤ２０は一対のビード
部１及び一対のサイドウォール部２（いずれも片側のみ
示す）とトレッド部（図示省略）からなり、ビード部１
内に埋設したビードコア３相互間にわたりこれらビード
部１、サイドウォール部２及びトレッド部を補強するラ
ジアル配列コード、特にスチールコードのゴム被覆にな
る１プライのカーカスプライ４と、このカーカスプライ
４の外周でトレッド部を強化するベルト（図示省略）と
を備えるのは慣例に従う。Referring to FIG. 1, a tire 20 includes a pair of bead portions 1 and a pair of sidewall portions 2 (both are shown on only one side) and a tread portion (not shown).
A one-ply carcass ply 4 which becomes a rubber covering of a bead core 1, a sidewall part 2 and a tread part, and particularly a rubber cord of a steel cord, extending between the bead cores 3 buried therein, and an outer periphery of the carcass ply 4 It is customary to provide a belt (not shown) for reinforcing the tread portion.
【００１１】カーカスプライ４は本体としてのプライの
他にビードコア３の回りをタイヤ内側から外側（以下単
に内側、外側という）に向けて巻上げた折返し部４ｔを
有し、図に示す例はハイターンアップである。カーカス
プライ４は、２本の曲線にて簡略図解したが厚み中央に
コード、望ましくはスチールコードを有し、その場合は
１プライで構成するものとし、各コードの周囲は隙間な
く被覆ゴムが取り囲む。The carcass ply 4 has a folded portion 4t wound around the bead core 3 from the inside of the tire to the outside (hereinafter simply referred to as inside and outside) in addition to the ply as a main body. Is up. The carcass ply 4 is schematically illustrated by two curves, but has a cord, preferably a steel cord, in the center of the thickness. In that case, the carcass ply 4 is constituted by one ply, and the periphery of each cord is surrounded by a covering rubber without gaps. .
【００１２】サイドウォール部２のゴム５は図示を省略
したトレッド部側方からビード部１領域まで延び、ビー
ド部１にてゴムチェーファ８とオーバーラップさせて連
結する。そのときゴムチェーファ８の外側表面のタイヤ
半径方向（以降半径方向と略す）外側端は配設目的から
してリム１０のフランジ１０ｆの外側縁を越える。The rubber 5 of the sidewall 2 extends from the side of the tread (not shown) to the region of the bead 1 and overlaps and connects with the rubber chafer 8 at the bead 1. At this time, the outer end of the outer surface of the rubber chafer 8 in the tire radial direction (hereinafter abbreviated as radial direction) exceeds the outer edge of the flange 10f of the rim 10 for the purpose of disposition.
【００１３】以上述べた各種構成部材とそれらの配置関
係の下で、タイヤ２０とリム１０との組立体に正規内圧
に対応する正規荷重を負荷すると、荷重直下位置のビー
ド部１及びサイドウォール部２はタイヤ幅方向外側にそ
して半径方向内側に向け撓曲変形、いわゆる倒れ込み変
形を生じる。この変形によりビード部１の外側表面がリ
ム１０のフランジ１０ｆと接触する終端位置、すなわち
半径方向最外側位置を図に符号Ａにて示すとき、位置Ａ
は図の矢印の向きに倒れ込みリム１０のフランジ１０ｆ
の位置Ａｆにとどまる。荷重負荷とそれからの解放で位
置Ａの点は位置Ａｆと位置Ａとの間で離合を繰り返す最
外側点であるから、ここでは位置Ａをタイヤ２０断面で
の最外側離合点と呼ぶ。When a normal load corresponding to the normal internal pressure is applied to the assembly of the tire 20 and the rim 10 under the above-described various components and their positional relationship, the bead portion 1 and the sidewall portion at the position immediately below the load are applied. No. 2 causes bending deformation toward the outside in the tire width direction and toward the inside in the radial direction, that is, so-called collapse deformation. Due to this deformation, the end position where the outer surface of the bead portion 1 comes into contact with the flange 10f of the rim 10, that is, the outermost position in the radial direction is indicated by the symbol A in FIG.
Is the flange 10f of the rim 10 which falls down in the direction of the arrow in the figure.
At the position Af. Since the point at the position A is the outermost point where the separation between the position Af and the position A is repeated by the load and the release from the load, the position A is referred to as the outermost separation point in the cross section of the tire 20 here.
【００１４】タイヤ２０とリム１０との内圧充填組立体
断面において、最外側離合点Ａを通るカーカスプライ４
の本体からの法線Ｌと、図示は省略したが図の上方のタ
イヤ断面幅位置を通る直線との間に挟まれる領域Ｒ内に
おいて、まずカーカスプライ４の折返し部４ｔの外側表
面に沿って硬質ゴム層６（図中、特に太い斜線を施して
示す）を配置するものとし、この硬質ゴム層６のゴム硬
度はカーカスプライ４の被覆ゴム硬度より高いものとす
る。In the section of the internal pressure filling assembly of the tire 20 and the rim 10, the carcass ply 4 passing through the outermost separation point A
First, along the outer surface of the folded portion 4t of the carcass ply 4, in a region R sandwiched between a normal line L from the It is assumed that a hard rubber layer 6 (particularly indicated by a thick oblique line in the drawing) is provided, and the rubber hardness of the hard rubber layer 6 is higher than the coating rubber hardness of the carcass ply 4.
【００１５】次に硬質ゴム層６の半径方向内側で折返し
部４ｔの外側表面に沿って軟質ゴム層７を配置する。こ
の配置は硬質ゴム層６の半径方向内側端面Ｓに軟質ゴム
層７の半径方向外側端面を接合させるものとし、また字
句通り軟質ゴム層７のゴム硬度はカーカスプライ４の被
覆ゴム硬度より低いことが必要である。Next, a soft rubber layer 7 is disposed radially inward of the hard rubber layer 6 and along the outer surface of the folded portion 4t. This arrangement is such that the radially outer end surface of the soft rubber layer 7 is joined to the radially inner end surface S of the hard rubber layer 6, and that the rubber hardness of the soft rubber layer 7 is literally lower than the coating rubber hardness of the carcass ply 4. is required.
【００１６】ここで、先に述べたサイドウォール部２か
らビード部１に至る間の倒れ込み変形が生じるとき、ビ
ード部１はあたかもビードコア３を支点とする回転形態
を採る。その結果、法線Ｌより半径方向内側での折返し
部４ｔ、より正確には折返し部４ｔのコード、特にスチ
ールコードより外側の領域ＲO に存在するゴムはリム１
０のフランジ１０ｆとの間で著しく圧縮される。Here, when the above-mentioned falling deformation occurs from the side wall portion 2 to the bead portion 1, the bead portion 1 adopts a rotating form with the bead core 3 as a fulcrum. As a result, the rubber present in the folded portion 4t radially inward of the normal line L, more precisely, in the cord of the folded portion 4t, in particular, in the region R O outside the steel cord is removed from the rim 1
It is significantly compressed between the zero flange 10f.
【００１７】この大きな圧縮による歪はフランジ１０ｆ
に沿って半径方向外側に向け軟質ゴム層７に大きな流動
変位を生じさせるので、ゴムは大きな剪断変形を受ける
ことになる。この剪断変形は繰り返しカーカスプライ４
の折返し部４ｔの外側表面に伝達される結果、従来はタ
イヤ走行が進むにつれ折返し部４ｔのコード、特にスチ
ールコードと被覆ゴムとの界面に、乃至コード近傍のゴ
ムにセパレーションを発生させることになる。The distortion caused by the large compression is caused by the flange 10f.
Causes a large flow displacement in the soft rubber layer 7 toward the radially outward side along the line, so that the rubber is subjected to a large shear deformation. This shear deformation is repeated by the carcass ply 4.
As a result, conventionally, as the tire travels, separation occurs at the cord of the folded portion 4t, particularly at the interface between the steel cord and the covering rubber, or at the rubber near the cord. .
【００１８】これに対し前記構成になるビード部１は、
領域ＲO より半径方向外側の領域Ｒにカーカスプライ４
の被覆ゴム硬度より高い硬度をもつ硬質ゴム層６を折返
し部４ｔに沿って配置しているので、タイヤへの荷重負
荷転動に伴い発生するリム１０のフランジ１０ｆから伝
達される軟質ゴム層７の流動は硬質ゴム層６があたかも
堰止めるように働き、少なくとも軟質ゴム層７の流動変
位量を抑制する。On the other hand, the bead portion 1 having the above structure is
Carcass ply than the region R O radially outer area R 4
Since the hard rubber layer 6 having a hardness higher than the coating rubber hardness of the rim 10 is disposed along the turn-back portion 4t, the soft rubber layer 7 transmitted from the flange 10f of the rim 10 generated when the load is rolled on the tire. Flow acts as if the hard rubber layer 6 is blocking, and at least suppresses the flow displacement of the soft rubber layer 7.
【００１９】この流動変位の抑制はカーカスプライ４の
折返し部４ｔ外側表面に作用する剪断歪を大幅に低減
し、これにより、元来折返し部４ｔに作用する剪断応力
緩和を狙いとしてカーカスプライ４の被覆ゴムより低硬
度の軟質ゴム層７を配置した効果はさらに顕著に高ま
り、セパレーション耐久性を改善することができる。い
うならば硬質ゴム層６と軟質ゴム層７との組合せ連係プ
レーの下でセパレーション耐久性を向上させるのであるThe suppression of the flow displacement greatly reduces the shear strain acting on the outer surface of the folded portion 4t of the carcass ply 4, thereby reducing the shear stress originally acting on the folded portion 4t. The effect of arranging the soft rubber layer 7 having a lower hardness than the coated rubber is further remarkably enhanced, and the separation durability can be improved. In other words, the separation durability is improved under the combined play of the hard rubber layer 6 and the soft rubber layer 7.
【００２０】硬質ゴム層６と軟質ゴム層７との外側に
は、耐屈曲性や耐候性に優れたサイドウォールゴム５
と、その半径方向下端でオーバーラップ接合するゴムチ
ェーファ８を設けるのは慣例に従う。Outside the hard rubber layer 6 and the soft rubber layer 7, a side wall rubber 5 having excellent bending resistance and weather resistance is provided.
It is customary to provide a rubber chafer 8 that overlaps at its lower end in the radial direction.
【００２１】また硬質ゴム層６はビード部１における半
径方向内側からの軟質ゴム層７の流動変位を半径方向外
側から抑制する役を有利に果たすため、硬質ゴム層６の
半径方向内側端が最外側離合点Ａから大きくかけ離れて
位置するのは好ましくなく、よって硬質ゴム層６の半径
方向内側端は、最外側離合点Ａと、そこから測ってタイ
ヤ断面高さの１０％に相当する高さ位置との間に存在す
る配置が望ましい。Since the hard rubber layer 6 advantageously suppresses the flow displacement of the soft rubber layer 7 from the radially inner side in the bead portion 1 from the radially outer side, the radially inner end of the hard rubber layer 6 is the most inward. It is not preferable to be located far away from the outer disengagement point A, so that the radially inner end of the hard rubber layer 6 has the outermost disjunction point A and a height corresponding to 10% of the tire section height measured therefrom. An arrangement existing between the positions is desirable.
【００２２】また上記同様な流動抑制の役を果たす上
で、硬質ゴム層６はある程度の厚さを有するのが望まし
く、好適には最大厚さＴはこの厚さ位置の直線ｍ上で測
った折返し部４ｔの外側ゴム厚さｔの４０％以上であ
る。また上記同様に実際上硬質ゴム層６の１００％モジ
ュラスは５０kgf/cm2 以上であることが望ましい。In order to fulfill the same role of suppressing flow as described above, it is desirable that the hard rubber layer 6 has a certain thickness. Preferably, the maximum thickness T is measured on a straight line m at this thickness position. It is 40% or more of the outer rubber thickness t of the folded portion 4t. Similarly to the above, it is desirable that the actual 100% modulus of the hard rubber layer 6 is 50 kgf / cm 2 or more.
【００２３】また軟質ゴム層７の１００％モジュラスが
２０kgf/cm2 以下であれば、硬質ゴム層６との組合せで
折返し部４ｔに作用する剪断応力低減効果に十分に寄与
し、さらに硬質ゴム層６と軟質ゴム層７との１００％モ
ジュラス差が大きい程剪断応力低減効果も大きくなる
が、実際上は軟質ゴム層７に対する硬質ゴム層６の１０
０％モジュラス比の値が３倍以上であるのが適合する。When the 100% modulus of the soft rubber layer 7 is not more than 20 kgf / cm 2 , the combination with the hard rubber layer 6 sufficiently contributes to the effect of reducing the shear stress acting on the folded portion 4t, and furthermore, the hard rubber layer As the 100% modulus difference between the soft rubber layer 6 and the soft rubber layer 7 increases, the effect of reducing the shear stress also increases.
It is suitable that the value of the 0% modulus ratio is 3 times or more.
【００２４】なお図１に示す符号９はスティフナであ
り、そのうち９ａは硬スティフナ、９ｂは軟スティフナ
であり、符号１１はインナーライナである点は従来構造
に従うが、特に硬スティフナ９ａ、軟スティフナ９ｂは
硬質ゴム層６と軟質ゴム層７との関連で最適な硬度及び
配列を考慮するのが良い。Reference numeral 9 shown in FIG. 1 denotes a stiffener, 9a denotes a hard stiffener, 9b denotes a soft stiffener, and 11 denotes an inner liner in accordance with the conventional structure. In particular, hard stiffener 9a and soft stiffener 9b are used. It is good to consider the optimal hardness and arrangement in relation to the hard rubber layer 6 and the soft rubber layer 7.
【００２５】[0025]
【実施例】建設車両用ラジアルタイヤ２０でサイズが３
７．００Ｒ５７であり、カーカスプライ４は１プライで
スチールコードのゴム被覆になる。ビード部１〜サイド
ウォール部２に至る構成について実施例１、２は図１
に、実施例３は図２に、そして実施例４は図３に従う。
実施例１〜４の図における主たる相違点は硬質ゴム層６
の半径方向内側端位置にあり、該内側端位置の最外離合
点Ａから測った高さはタイヤ断面高さの、実施例１、２
は２％、実施例３は８％、実施例４は３％とした。EXAMPLE A construction vehicle radial tire 20 of size 3
7.00R57, and the carcass ply 4 is covered with a steel cord rubber in one ply. Embodiments 1 and 2 show the configuration from bead portion 1 to sidewall portion 2 in FIG.
Example 3 follows FIG. 2 and Example 4 follows FIG.
The main difference in the drawings of Examples 1 to 4 is that the hard rubber layer 6
And the height measured from the outermost departure point A of the inner end position is the tire cross-section height in Examples 1 and 2.
Was 2%, Example 3 was 8%, and Example 4 was 3%.
【００２６】各実施例の効果を検証するため図４に同様
断面を示す従来例のタイヤ２０Ａを準備した。従来例も
含め表１に、ゴムの１００％モジュラス（kgf/cm2)につ
き、カーカスプライ４の被覆ゴムはカーカスゴムＭ100
（kgf/cm2)、硬質ゴム層６は硬質ゴム層Ｍ100 （kgf/cm
2)、軟質ゴム層７は軟質ゴム層Ｍ100 （kgf/cm2)、そし
て硬質ゴム層６の厚さＴの折返し部外側ゴム厚さｔに対
する比率（％）を硬質ゴム層厚さＴ比率（％）、とそれ
ぞれ略記してそれぞれの値を示す。In order to verify the effect of each embodiment, a conventional tire 20A having a cross section similar to that shown in FIG. 4 was prepared. In Table 1 including the conventional example, the coating rubber of the carcass ply 4 is carcass rubber M 100 per 100% modulus (kgf / cm 2 ) of the rubber.
(Kgf / cm 2 ), and the hard rubber layer 6 is a hard rubber layer M 100 (kgf / cm 2 ).
2 ), the soft rubber layer 7 is a soft rubber layer M 100 (kgf / cm 2 ), and the ratio (%) of the thickness T of the hard rubber layer 6 to the outside rubber thickness t of the folded portion is the hard rubber layer thickness T ratio. (%), And the respective values are abbreviated.
【００２７】[0027]
【表１】 [Table 1]
【００２８】上記５種類のタイヤを供試タイヤとして、
ドラムによるビード耐久性試験により比較評価した。試
験方法及び試験条件は下記の通り。 （１）ベルト故障を先行させず、確実にビード部故障が
発生するように、トレッド部のトレッドゴムを削り取っ
た。 （２）正規内圧７kgf/cm2 を充填し、表面速度１０km/h
で回転するドラムに当初荷重は５１．５トン（約１００
％ロード）を負荷し、所定時間走行後は段階的に荷重を
増加させ、５種類のタイヤの何れか１種類のタイヤにビ
ード部故障が生じたところで試験は全数打ち切りとす
る。The above five types of tires were used as test tires.
Comparative evaluation was performed by a bead durability test using a drum. The test method and test conditions are as follows. (1) The tread rubber of the tread portion was scraped off so that the bead portion failure occurred without causing the belt failure to precede. (2) Filling with a regular internal pressure of 7 kgf / cm 2 , surface speed of 10 km / h
The initial load on the drum rotating at 51.5 tons (about 100
% Load), and after running for a predetermined time, the load is increased step by step. When any one of the five tires has a bead failure, the test is terminated.
【００２９】最初に従来例のタイヤに外観から明確に確
認できるビード部故障（ビード部外側の故障）が発生し
たので、全タイヤの試験を打ち切り試験機から取り外し
てビード部故障の有無及び故障の程度を解剖により確か
めた。First, since a bead failure (failure outside the bead portion) which can be clearly confirmed from the appearance of the conventional tire occurred, all tire tests were discontinued and removed from the testing machine to determine whether or not there was a bead failure and to determine whether there was a bead failure. The extent was confirmed by dissection.
【００３０】その結果、従来例は更めて解剖に付すまで
もなく、著しいセパレーション故障がカーカスプライ折
返し部の外側表面周りに発生していたのに対し、実施例
１、３は折返し部４ｔの外側に外観からそれと認めるこ
とができない程度の微小なセパレーションが見出された
に過ぎず、実施例２、４にはセパレーションの兆候すら
認めることができなかった。なお試みに新品タイヤ重量
を測定しところいずれのタイヤも誤差範囲程度の微差に
収まっていた。As a result, in the conventional example, a significant separation failure occurred around the outer surface of the folded portion of the carcass ply without necessitating further dissection. Only a minute separation was found on the outside that could not be recognized from the appearance, and no signs of separation could be recognized in Examples 2 and 4. When the weight of a new tire was measured in trial, all tires were within a small difference of about an error range.
【００３１】[0031]
【発明の効果】この発明によれば、補強部材などの追加
部材の配置を必要とせず、よってタイヤ重量増加を伴う
ことなく高生産性を保持した上で、ビード部耐久性を有
効に向上させることができる重荷重用空気入りラジアル
タイヤを提供することができる。According to the present invention, it is not necessary to dispose an additional member such as a reinforcing member, so that the bead portion durability can be effectively improved while maintaining high productivity without increasing the tire weight. A pneumatic radial tire for heavy loads that can be provided.
【図１】この発明による一実施例タイヤの要部断面図で
ある。FIG. 1 is a sectional view of a main part of an embodiment tire according to the present invention.
【図２】この発明による別の実施例タイヤの要部断面図
である。FIG. 2 is a sectional view of a main part of another example tire according to the present invention.
【図３】この発明による他の実施例タイヤの要部断面図
である。FIG. 3 is a sectional view of a main part of another embodiment tire according to the present invention.
【図４】従来タイヤの要部断面図である。FIG. 4 is a sectional view of a main part of a conventional tire.
１ ビード部 ２ サイドウォール部 ３ ビードコア ４ カーカスプライ ４ｔ 折返し部 ５ サイドウォールゴム ６ 硬質ゴム層 ７ 軟質ゴム層 ８ ゴムチェーファ ９ スティフナ ９ａ 硬スティフナ ９ｂ 軟スティフナ １０ リム １０ｆ フランジ ２０、２０Ａ 重荷重用空気入りラジアルタイヤ Ａ 荷重負荷時のビード部外側表面の半径方向最外側接
触位置 Ｌ 位置Ａの点を通るカーカスプライからの法線 Ｒ 法線Ｌとタイヤ断面幅を通る直線との間の領域 ＲO 法線Ｌより半径方向内側の領域 ｍ 硬質ゴム層最大厚さ位置の直線 Ｔ 直線ｍ上の硬質ゴム層最大厚さ ｔ 直線ｍ上の折返し部のゴム厚さ Ｓ 硬質ゴム層の半径方向内側端縁面DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Bead core 4 Carcass ply 4t Folded part 5 Sidewall rubber 6 Hard rubber layer 7 Soft rubber layer 8 Rubber chafer 9 Stiffener 9a Hard stiffener 9b Soft stiffener 10 Rim 10f Flange 20 and 20A Pneumatic radial for heavy load A The outermost contact position in the radial direction of the bead portion outer surface when a load is applied L The area between the normal line R from the carcass ply passing through the point at the position A and the straight line passing through the tire section width R O normal line L Radially inner area m Straight line at hard rubber layer maximum thickness position T Hard rubber layer maximum thickness on straight line m t Rubber thickness of folded portion on straight line m S Radial inner edge surface of hard rubber layer
Claims (4)
ル部と、トレッド部とからなり、これら各部をビード部
内に埋設したビードコア相互間にわたり補強するラジア
ル配列コードのゴム被覆になるカーカスプライと、該カ
ーカスプライの外周に配置したベルトとを備え、カーカ
スプライはビードコア周りを巻上げた折返し部を有する
重荷重用空気入りラジアルタイヤにおいて、 上記タイヤの正規内圧を該タイヤとその適用リムとの組
立体に充填して正規荷重を負荷し解放したときの組立体
断面に関し、荷重負荷時におけるビード部表面のリムの
フランジとの接触終端位置を通るカーカスプライからの
法線と、タイヤ断面幅位置を通る直線との間に挟まれる
領域内に、カーカスプライ折返し部の外側表面に沿って
カーカスプライコードの被覆ゴムより高い硬度をもつ硬
質ゴム層を配置する一方、該硬質ゴム層のタイヤ半径方
向内側面に接合させると共に同上折返し部の外側表面に
沿わせて上記被覆ゴムより低い硬度をもつ軟質ゴム層を
配置して成ることを特徴とする重荷重用空気入りラジア
ルタイヤ。A carcass ply comprising a pair of beads, a pair of sidewalls, and a tread portion, the carcass ply being a rubber coating of a radial array cord for reinforcing each of these portions between bead cores embedded in the bead portion; A belt disposed on the outer periphery of the carcass ply, wherein the carcass ply is a heavy-duty pneumatic radial tire having a folded portion wound around the bead core, wherein the regular internal pressure of the tire is filled into an assembly of the tire and its applicable rim. With respect to the assembly cross section when a normal load is applied and released, a normal line from the carcass ply passing through the contact end position of the bead portion surface with the rim flange at the time of load application, and a straight line passing through the tire cross section width position In the area sandwiched between the carcass ply cords along the outer surface of the carcass ply turnover While a hard rubber layer having a hardness higher than that of the coated rubber is arranged on the inner surface of the hard rubber layer in the tire radial direction, a soft rubber layer having a lower hardness than the coated rubber is formed along the outer surface of the folded portion. A pneumatic radial tire for heavy loads characterized by being arranged.
が、上記法線のビード部表面位置と、該位置から測って
タイヤ断面高さの１０％に相当する高さ位置との間に存
在し、硬質ゴム層は半径方向内側に最大厚さ部分を有
し、この最大厚さは、その方向に測った折返し部からタ
イヤ表面までのゴム厚さの４０％以上であり、硬質ゴム
層の１００％モジュラスが５０kgf/cm2 以上である請求
項１に記載したタイヤ。2. A tire radially inner end of the hard rubber layer exists between a bead portion surface position of the normal and a height position corresponding to 10% of a tire sectional height measured from the position. The hard rubber layer has a maximum thickness portion radially inward, and the maximum thickness is 40% or more of the rubber thickness measured from the folded portion to the tire surface in the direction, and the hard rubber layer has a maximum thickness. The tire according to claim 1, wherein the 100% modulus is 50 kgf / cm 2 or more.
２０kgf/cm2 以下である請求項１に記載したタイヤ。3. The tire according to claim 1, wherein the soft rubber layer has a 100% modulus of 20 kgf / cm 2 or less.
の１００％モジュラス比の値は３倍以上である請求項２
又は３に記載したタイヤ。4. The value of the 100% modulus ratio of the hard rubber layer to the soft rubber layer is three times or more.
Or the tire described in 3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17912096A JP3647977B2 (en) | 1996-07-09 | 1996-07-09 | Heavy duty pneumatic radial tire |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17912096A JP3647977B2 (en) | 1996-07-09 | 1996-07-09 | Heavy duty pneumatic radial tire |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1024712A true JPH1024712A (en) | 1998-01-27 |
| JP3647977B2 JP3647977B2 (en) | 2005-05-18 |
Family
ID=16060362
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17912096A Expired - Fee Related JP3647977B2 (en) | 1996-07-09 | 1996-07-09 | Heavy duty pneumatic radial tire |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3647977B2 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11227423A (en) * | 1998-02-18 | 1999-08-24 | Bridgestone Corp | Pneumatic radial tire for heavy load |
| JP2003512214A (en) * | 1998-12-24 | 2003-04-02 | ソシエテ ド テクノロジー ミシュラン | Beads for radial tires |
| JP2011218972A (en) * | 2010-04-09 | 2011-11-04 | Bridgestone Corp | Pneumatic radial tire for heavy load |
| US20120160392A1 (en) * | 2010-12-22 | 2012-06-28 | Philip Carl Van Riper | Tire with optimized chafer |
| KR20190077462A (en) | 2017-04-17 | 2019-07-03 | 요코하마 고무 가부시키가이샤 | Pneumatic tire |
| CN111823782A (en) * | 2019-04-16 | 2020-10-27 | 韩国轮胎与科技株式会社 | Pneumatic tire having bead apex with multiple rubber layers |
-
1996
- 1996-07-09 JP JP17912096A patent/JP3647977B2/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11227423A (en) * | 1998-02-18 | 1999-08-24 | Bridgestone Corp | Pneumatic radial tire for heavy load |
| JP2003512214A (en) * | 1998-12-24 | 2003-04-02 | ソシエテ ド テクノロジー ミシュラン | Beads for radial tires |
| JP2011218972A (en) * | 2010-04-09 | 2011-11-04 | Bridgestone Corp | Pneumatic radial tire for heavy load |
| US20120160392A1 (en) * | 2010-12-22 | 2012-06-28 | Philip Carl Van Riper | Tire with optimized chafer |
| KR20190077462A (en) | 2017-04-17 | 2019-07-03 | 요코하마 고무 가부시키가이샤 | Pneumatic tire |
| DE112018002044T5 (en) | 2017-04-17 | 2020-01-16 | The Yokohama Rubber Co., Ltd. | tire |
| CN111823782A (en) * | 2019-04-16 | 2020-10-27 | 韩国轮胎与科技株式会社 | Pneumatic tire having bead apex with multiple rubber layers |
| US11485177B2 (en) * | 2019-04-16 | 2022-11-01 | Hankook Tire & Technology Co., Ltd | Pneumatic tire with bead filler applied with multiple rubber layer |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3647977B2 (en) | 2005-05-18 |
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