JPH08175130A - Bead part structure of pneumatic tire - Google Patents

Bead part structure of pneumatic tire

Info

Publication number
JPH08175130A
JPH08175130A JP33789594A JP33789594A JPH08175130A JP H08175130 A JPH08175130 A JP H08175130A JP 33789594 A JP33789594 A JP 33789594A JP 33789594 A JP33789594 A JP 33789594A JP H08175130 A JPH08175130 A JP H08175130A
Authority
JP
Japan
Prior art keywords
stiffener
bead
outer end
hardness
radially
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.)
Pending
Application number
JP33789594A
Other languages
Japanese (ja)
Inventor
Norihiro Shimada
紀寛 島田
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bridgestone Corp
Original Assignee
Bridgestone Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Bridgestone Corp filed Critical Bridgestone Corp
Priority to JP33789594A priority Critical patent/JPH08175130A/en
Publication of JPH08175130A publication Critical patent/JPH08175130A/en
Pending legal-status Critical Current

Links

Classifications

    • 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
    • B60C15/06—Flipper strips, fillers, or chafing strips and reinforcing layers for the construction of the bead
    • B60C15/0603—Flipper strips, fillers, or chafing strips and reinforcing layers for the construction of the bead characterised by features of the bead filler or apex
    • B60C15/0607—Flipper strips, fillers, or chafing strips and reinforcing layers for the construction of the bead characterised by features of the bead filler or apex comprising several parts, e.g. made of different rubbers

Landscapes

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

Abstract

PURPOSE: To suppress the separation in the vicinity of an outer end in the radial direction of a fold-back part while preventing the heat generation at the bead part and the increase in the rolling resistance. CONSTITUTION: The distortion generated in a side wall part 24 by the loaded rolling is absorbed during the transmission by the deformation of a soft (<=56 deg.) outer stiffener part 21 surrounding the periphery of the outer end in the radial direction of a fold-back part 16, and the compressive distortion exerted on the rubber around the outer stiffener part 21 is reduced. This effect can be obtained only by setting the hardness of the rubber of the outer stiffener part 21, and the increase in the bending rigidity of a bead part 26 or in the weight of a tire is prevented.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】この発明は、ビード部耐久性を向
上させた空気入りタイヤのビード部構造に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bead structure for a pneumatic tire having improved bead durability.

【０００２】[0002]

【従来の技術】従来の空気入りタイヤのビード部構造と
しては、例えば、ほぼ半径方向に延びるカーカス層の本
体部と、前記本体部の軸方向外側において該本体部に沿
って延びるカーカス層の折返し部と、前記本体部と折返
し部との間に配置されたビードコアと、半径方向内側部
が本体部と折返し部との間に密着配置されるとともに、
その半径方向内端がビードコアに接し、半径方向外側部
が本体部の軸方向外側に密着配置されたスティフナー
と、を備え、前記スティフナーを、外側プライの半径方
向外側端より半径方向内側に軸方向外側端部が位置する
境界面によって、半径方向外側に位置するとともにカー
カス形状の保持機能を果たし、ショアＡ硬度が58度から
68度のゴムからなる軟スティフナー部と、半径方向内側
に位置するとともに転動時におけるビード部の倒れ込み
抑制機能を果たし、ショアＡ硬度が75度以上のゴムから
なる硬スティフナー部とに区分するとともに、該軟ステ
ィフナー部を外側プライの半径方向外側端より半径方向
外側まで延在させたものが知られている。2. Description of the Related Art As a conventional bead structure of a pneumatic tire, for example, a carcass layer body extending substantially in a radial direction and a carcass layer extending along the body portion axially outside the body portion are folded back. A portion, a bead core arranged between the body portion and the folded portion, and a radially inner portion is closely arranged between the body portion and the folded portion,
A stiffener whose inner end in the radial direction is in contact with the bead core and whose outer side in the radial direction is closely arranged on the outer side in the axial direction of the main body; and the stiffener in the inner side in the radial direction from the outer end in the radial direction of the outer ply. With the boundary surface where the outer end is located, it is located on the outer side in the radial direction and also has a carcass shape holding function, and the Shore A hardness is from 58 degrees.
It is divided into a soft stiffener part made of 68 ° rubber and a hard stiffener part made of rubber with a Shore A hardness of 75 ° or more, which is located on the inner side in the radial direction and has a function of suppressing collapse of the bead part during rolling. It is known that the soft stiffener portion extends radially outward from the radially outer end of the outer ply.

【０００３】そして、このような空気入りタイヤを荷重
を負荷した状態で走行させると、荷重直下（接地側）の
サイドウォール部が撓みながら倒れ込むため、この撓み
がビード部に伝達されるが、このとき、カーカス層の折
返し部は内部にスチールコードが埋設されて剛性が高く
殆ど変形することがないため、前記撓みによりこの折返
し部の半径方向外側端の周囲を囲むゴムに大きな圧縮歪
が発生するのである。そして、このような圧縮歪は走行
により荷重直下となる毎に繰り返し発生するため、該折
返し部の半径方向外側端近傍のゴムに亀裂が生じ、つい
にはセパレーションへと進展することがある。When such a pneumatic tire is run under a load, the sidewall portion immediately below the load (ground contact side) bends and falls down, and this deflection is transmitted to the bead portion. At this time, since the steel cord is embedded in the folded portion of the carcass layer and the rigidity is high and hardly deformed, a large compression strain is generated in the rubber surrounding the radially outer end of the folded portion due to the bending. Of. Since such a compressive strain is repeatedly generated just below the load due to running, a crack may occur in the rubber near the outer end in the radial direction of the folded portion and eventually progress to separation.

【０００４】このような折返し端セパレーションを防止
するため、硬スティフナー部のショアＡ硬度を高くした
り、あるいは、折返し部の軸方向外側に密着し非伸長性
コードが埋設されたチェーファーを、その半径方向外側
端が折り返し部の半径方向外側端より半径方向外側にな
るよう配置して、ビード部の曲げ剛性を向上させ、これ
により、サイドウォール部の倒れ込みを抑制して前記圧
縮歪を抑制するようにすることが提案された。In order to prevent such a folded end separation, the shore A hardness of the hard stiffener portion is increased, or a chafer in which a non-stretchable cord is buried so as to be in close contact with the axially outer side of the folded portion. Arranged so that the radially outer end is radially outer than the radially outer end of the folded portion to improve the bending rigidity of the bead portion, thereby suppressing the collapse of the sidewall portion and suppressing the compression strain. It was suggested to do so.

【０００５】[0005]

【発明が解決しようとする課題】しかしながら、このよ
うなものにあっては、ビード部の曲げ剛性が高くなり、
しかもタイヤ重量が大きくなるため、走行時にビード部
が発熱するとともに、タイヤの転がり抵抗が悪化すると
いう問題点があり、しかも、後者にあっては、チェーフ
ァーの半径方向外側端近傍に大きな圧縮歪が繰り返し生
じてセパレーションを発生してしまうという問題点もあ
る。However, in such a case, the bending rigidity of the bead portion becomes high,
Moreover, since the weight of the tire becomes large, the bead part generates heat during running and the rolling resistance of the tire deteriorates, and in the latter case, there is a large compressive strain near the radial outer end of the chafer. There is also a problem that separation occurs repeatedly and the separation occurs.

【０００６】この発明は、ビード部における発熱および
転がり抵抗の増大を防止しながら、外側プライの半径方
向外側端近傍におけるセパレーションを抑制することが
できる空気入りタイヤのビード部構造を提供することを
目的とする。SUMMARY OF THE INVENTION It is an object of the present invention to provide a bead structure for a pneumatic tire, which can prevent heat generation and rolling resistance increase in the bead, and can suppress separation near the outer end in the radial direction of the outer ply. And

【０００７】[0007]

【課題を解決するための手段】このような目的は、ほぼ
半径方向に延びるカーカス層の本体部と、前記本体部の
軸方向外側に配置されるとともに該本体部に沿って延び
る外側プライと、前記本体部と外側プライとの間に配置
されたビードコアと、半径方向内側部が本体部と外側プ
ライとの間に密着配置されるとともに、その半径方向内
端がビードコアに接し、半径方向外側部が本体部の軸方
向外側に密着配置されたスティフナーと、を備えた空気
入りタイヤのビード部構造において、前記スティフナー
を、外側プライの半径方向外側端より半径方向内側に軸
方向外側端部が位置する境界面によって、半径方向外側
に位置しショアＡ硬度が56度以下のゴムからなる外側ス
ティフナー部と、半径方向内側に位置しショアＡ硬度が
58度以上のゴムからなる内側スティフナー部とに区分す
るとともに、該外側スティフナー部を外側プライの半径
方向外側端より半径方向外側まで延在させることにより
達成することができる。SUMMARY OF THE INVENTION Such an object is to provide a carcass layer body portion that extends in a substantially radial direction, and an outer ply disposed axially outside the body portion and extending along the body portion. A bead core arranged between the body portion and the outer ply and a radially inner portion are closely arranged between the body portion and the outer ply, and a radially inner end of the bead core contacts the bead core. In a bead structure of a pneumatic tire including a stiffener closely arranged on the outer side of the main body in the axial direction, the stiffener is positioned so that the axially outer end is located radially inward from the radially outer end of the outer ply. The outer stiffener portion made of rubber having a Shore A hardness of 56 degrees or less is located on the outer side in the radial direction, and the Shore A hardness is located on the inner side in the radial direction.
This can be achieved by dividing the outer stiffener portion from the radially outer end of the outer ply in the radial direction while dividing the outer stiffener portion from the inner stiffener portion made of rubber having a degree of 58 degrees or more.

【０００８】[0008]

【作用】荷重が負荷されている状態で空気入りタイヤが
走行すると、荷重直下（接地側）のサイドウォール部が
撓みながら軸方向外側に倒れ込み、この撓みがビード部
に伝達されて、接地側に位置する外側プライの半径方向
外側端の周囲を囲むゴムに大きな圧縮歪を生じるおそれ
がある。しかしながら、この発明では、スティフナー
を、外側プライの半径方向外側端より半径方向内側に軸
方向外側端部が位置する境界面によって、半径方向外側
に位置しショアＡ硬度が56度以下のゴムからなる外側ス
ティフナー部と、半径方向内側に位置しショアＡ硬度が
58度以上のゴムからなる内側スティフナー部とに区分す
るとともに、該外側スティフナー部を外側プライの半径
方向外側端より半径方向外側まで延在させることによ
り、外側プライの半径方向外側端の周囲を変形が容易な
軟質のゴム（外側スティフナー部）によって囲むように
したので、前述した歪は大きな体積の外側スティフナー
部が変形することで伝達中に吸収され、これにより、外
側プライの半径方向外側端の周囲を囲むゴムに作用する
圧縮歪が低減され、外側プライの半径方向外側端におけ
るセパレーションが抑制されるのである。しかも、この
発明では外側スティフナー部のショアＡ硬度を所定の値
とするだけであるため、ビード部の曲げ剛性が高くなっ
たり、タイヤ重量が大きくなるようなことはなく、ビー
ド部における発熱および転がり抵抗が増大することもな
い。[Function] When a pneumatic tire runs under a load, the sidewall portion immediately below the load (grounding side) bends and falls to the outside in the axial direction, and this bending is transmitted to the bead portion to the grounding side. A large compressive strain may occur in the rubber surrounding the radially outer end of the positioned outer ply. However, in the present invention, the stiffener is made of rubber having a Shore A hardness of 56 degrees or less, which is located radially outward by the boundary surface in which the axial outer end is located radially inward from the radial outer end of the outer ply. Located on the outer stiffener and radially inward, the Shore A hardness is
The outer stiffener portion is deformed around the radially outer end of the outer ply by dividing the outer stiffener portion from the radially outer end of the outer ply in the radial direction while dividing the outer stiffener portion from the inner stiffener portion made of rubber of 58 degrees or more. Since it is surrounded by a soft rubber (outer stiffener part), the above strain is absorbed during transmission due to the deformation of the outer stiffener part with a large volume, and this allows the radial outer end of the outer ply to be absorbed. The compressive strain acting on the surrounding rubber is reduced, and the separation at the radially outer end of the outer ply is suppressed. Moreover, in the present invention, since the Shore A hardness of the outer stiffener portion is only set to a predetermined value, the bending rigidity of the bead portion does not increase and the tire weight does not increase, and heat generation and rolling at the bead portion occur. The resistance does not increase.

【０００９】また、請求項２に記載のように構成すれ
ば、外側プライの半径方向外側端の周囲が外側スティフ
ナー部より歪の発生しにくいカバーゴム体により局部的
に囲まれて補強され、これにより、外側プライの半径方
向外側端におけるセパレーションの発生がさらに抑制さ
れる。According to the second aspect of the present invention, the periphery of the outer end of the outer ply in the radial direction is locally surrounded and reinforced by the cover rubber body which is more resistant to strain than the outer stiffener portion. As a result, the occurrence of separation at the radially outer end of the outer ply is further suppressed.

【００１０】[0010]

【実施例】以下、この発明の第１実施例を図面に基づい
て説明する。図１、２において、11は空気入りラジアル
タイヤであり、このタイヤ11は一対のビードコア12と、
トロイダル状をしたカーカス層13を有し、このカーカス
層13は少なくとも１枚、ここでは１枚のカーカスプライ
14から構成されている。このカーカス層13は両方のビー
ドコア12の軸方向内側でほぼ半径方向外側に向かって延
びる本体部15と、本体部15の半径方向内端からビードコ
ア12を囲みながら折り返されることにより、本体部15の
軸方向外側に配置されるとともに、半径方向外側に向か
って該本体部15とほぼ平行に延びる外側プライとしての
折返し部16とを有する。そして、前記カーカスプライ14
の内部にはスチール、アラミド繊維等からなりタイヤ赤
道面Ｓに直交して（ラジアル方向に）延びるコードが多
数本埋設されている。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, 11 is a pneumatic radial tire, and this tire 11 includes a pair of bead cores 12,
The carcass layer 13 has a toroidal shape. The carcass layer 13 has at least one carcass ply.
It consists of 14. This carcass layer 13 is folded back while surrounding the bead core 12 from the main body portion 15 that extends axially inward of both bead cores 12 toward the outer side in the substantially radial direction, and the inner periphery of the main body portion 15 while surrounding the bead core 12. It has a folded-back portion 16 as an outer ply which is arranged on the outer side in the axial direction and extends substantially parallel to the main body portion 15 toward the outer side in the radial direction. And the carcass ply 14
A large number of cords made of steel, aramid fiber or the like and extending orthogonally to the tire equatorial plane S (in the radial direction) are embedded in the inside of the.

【００１１】20は一対のスティフナーであり、これらの
スティフナー20は半径方向内側部が前記本体部15と折返
し部16との間にこれらに密着した状態で配置され、その
半径方向外側部が本体部15の軸方向外側にこれに密着し
た状態で配置され、タイヤ最大幅近傍まで延びている。
また、これらスティフナー20の半径方向内端はビードコ
ア12に接している。各スティフナー20は軸方向外側端部
が折返し部16の半径方向外側端23より半径方向内側、こ
こではビードコア12近傍に位置し、本体部15に接近する
に従い半径方向外側に向かうよう傾斜している境界面Ｘ
によって外側スティフナー部21と内側スティフナー部22
とに区分されている。そして、外側スティフナー部21は
前記境界面Ｘより半径方向外側に位置するとともに、折
返し部16の半径方向外側端23より半径方向外側まで延在
しており、一方、内側スティフナー部22は境界面Ｘより
半径方向内側に位置している。ここで、前記外側スティ
フナー部21はショアＡ硬度が56度以下の変形が容易な軟
質のゴムから構成されているため、前記折返し部16の半
径方向外側端23の周囲は変形が容易な軟質の外側スティ
フナー部21によって囲まれることになり、一方、内側ス
ティフナー部22は外側スティフナー部21よりショアＡ硬
度が 2度以上高い、即ちショアＡ硬度が58度以上、この
実施例では75度以上の硬質ゴムから構成されている。こ
こで、内側スティフナー部22のショアＡ硬度を58度以上
としたのは、本体部15の変形およびビードコア12の形崩
れを効果的に抑制するためであり、一方、外側スティフ
ナー部21のショアＡ硬度を56度以下としたのは、後述の
ようにサイドウォール部24に生じた歪を効果的に吸収す
るためである。Reference numeral 20 denotes a pair of stiffeners. These stiffeners 20 are arranged such that the radially inner portion is in close contact with the body portion 15 and the folded portion 16, and the radially outer portion thereof is the body portion. It is arranged on the outer side in the axial direction of 15 so as to be in close contact therewith, and extends to the vicinity of the maximum tire width.
The inner ends of these stiffeners 20 in the radial direction are in contact with the bead core 12. Each stiffener 20 has an axially outer end located radially inward from a radially outer end 23 of the folded portion 16, here located near the bead core 12, and inclined toward the radially outer side as it approaches the main body 15. Boundary X
Outer stiffener part 21 and inner stiffener part 22 by
It is divided into and. The outer stiffener portion 21 is located radially outside of the boundary surface X and extends radially outward from the radially outer end 23 of the folded portion 16, while the inner stiffener portion 22 is located at the boundary surface X. It is located radially inward. Here, since the outer stiffener portion 21 is made of a soft rubber having a Shore A hardness of 56 degrees or less and is easily deformed, the periphery of the radially outer end 23 of the folded portion 16 is easily deformed. The outer stiffener portion 21 is surrounded by the outer stiffener portion 22, while the inner stiffener portion 22 has a Shore A hardness of 2 degrees or more higher than the outer stiffener portion 21, that is, a Shore A hardness of 58 degrees or more, and in this embodiment, a hardness of 75 degrees or more. It is made of rubber. Here, the Shore A hardness of the inner stiffener portion 22 is set to 58 degrees or more in order to effectively suppress the deformation of the main body portion 15 and the deformation of the bead core 12, while the Shore A hardness of the outer stiffener portion 21 is set. The hardness is set to 56 degrees or less in order to effectively absorb the strain generated in the sidewall portion 24 as described later.

【００１２】各折返し部16の半径方向外側端23の周囲に
は該半径方向外側端23を局部的に囲むカバーゴム体25が
配置され、これらカバーゴム体25のショアＡ硬度は、折
返し部16の半径方向外側端23におけるセパレーションの
発生を抑制するために、外側スティフナー部21のショア
Ａ硬度（56度）以上とする必要がある。また、これらカ
バーゴム体25のショアＡ硬度は、前記セパレーションの
発生を確実に抑制するためには、内側スティフナー部22
のショアＡ硬度、即ち58度以上とすることが好ましい。
ここで、これらカバーゴム体25の幅ｔはプライ端部の段
付きを防止するという理由からカーカスプライ14内に埋
設されたコードの直径以上とすることが好ましく、ま
た、プライ端の切断面にはメッキ層がないことから、カ
バーゴム体25として亀裂性の良好なゴムを用いた方がよ
い。A cover rubber body 25 is arranged around the radially outer end 23 of each of the folded portions 16 so as to locally surround the radially outer end 23. The Shore A hardness of these cover rubber bodies 25 is determined by the folded portion 16. In order to suppress the occurrence of separation at the outer end 23 in the radial direction, the Shore A hardness of the outer stiffener portion 21 (56 degrees) or more is required. Further, the Shore A hardness of these cover rubber bodies 25 is set so that the inner stiffener portion 22 is required to surely suppress the occurrence of the separation.
Shore A hardness of, ie, 58 degrees or more is preferable.
Here, it is preferable that the width t of the cover rubber body 25 is equal to or larger than the diameter of the cord embedded in the carcass ply 14 in order to prevent stepping of the ply end portion. Since there is no plating layer, it is better to use rubber having good cracking property as the cover rubber body 25.

【００１３】次に、このようなタイヤ11を荷重を負荷し
ながら走行させると、荷重直下（接地側）のサイドウォ
ール部24が撓みながら軸方向外側に倒れ込み、この撓み
がビード部26に伝達される。このとき、前述のように折
返し部16の半径方向外側端23の周囲を変形が容易な軟質
の外側スティフナー部21によって囲むようにしたので、
前述した歪はこの大きな体積の外側スティフナー部21が
変形することで伝達中に吸収され、これにより、折返し
部16の半径方向外側端23の周囲のゴムに作用する圧縮歪
が低減され、折返し部16の半径方向外側端23におけるセ
パレーションが抑制される。しかも、この実施例では外
側スティフナー部21のショアＡ硬度を前述のような値と
するだけでよいので、ビード部26の曲げ剛性が高くなっ
たり、タイヤ重量が大きくなるようなことはなく、ビー
ド部26における発熱および転がり抵抗が増大することも
ない。さらに、この折返し部16の半径方向外側端23の周
囲は、前述のように外側スティフナー部21より歪の発生
しにくいカバーゴム体25により局部的に囲まれて補強さ
れているので、折返し部16の半径方向外側端23における
セパレーションの発生がさらに抑制される。Next, when such a tire 11 is run while applying a load, the sidewall portion 24 immediately below the load (ground contact side) bends and falls axially outward, and this bend is transmitted to the bead portion 26. It At this time, as described above, since the periphery of the radially outer end 23 of the folded portion 16 is surrounded by the soft outer stiffener portion 21 which is easily deformed,
The above-mentioned strain is absorbed during transmission by the deformation of the outer stiffener portion 21 having a large volume, whereby the compressive strain acting on the rubber around the radially outer end 23 of the folding portion 16 is reduced, and the folding portion is reduced. Separation at the radially outer end 23 of 16 is suppressed. Moreover, in this embodiment, since the Shore A hardness of the outer stiffener portion 21 may be set to the above-mentioned value, the bending rigidity of the bead portion 26 does not increase and the tire weight does not increase. Also, heat generation and rolling resistance in the portion 26 do not increase. Further, since the periphery of the radially outer end 23 of the folded-back portion 16 is locally surrounded and reinforced by the cover rubber body 25, which is more resistant to distortion than the outer stiffener portion 21, as described above, the folded-back portion 16 is provided. The occurrence of separation at the radially outer end 23 of is further suppressed.

【００１４】図３はこの発明の第２実施例を示す図であ
る。この実施例においては、外側スティフナー部31と内
側スティフナー部32との境界面Ｂの軸方向外端部を折返
し部16の半径方向外側端23より若干量だけ半径方向内側
に位置させるとともに、内側スティフナー部32を前記第
１実施例で説明した境界面Ｘと同一位置にある境界面Ｃ
によって半径方向外側に位置する第１内側スティフナー
部33と、半径方向内側に位置する第２内側スティフナー
部34とに区分し、前記第１内側スティフナー部33をショ
アＡ硬度が58度から68度のゴムから、一方、第２内側ス
ティフナー部34をショアＡ硬度が75度以上のゴムから構
成している。FIG. 3 is a diagram showing a second embodiment of the present invention. In this embodiment, the axial outer end of the boundary surface B between the outer stiffener portion 31 and the inner stiffener portion 32 is located slightly inward in the radial direction from the radially outer end 23 of the folding portion 16, and the inner stiffener is also provided. The part 32 has a boundary surface C located at the same position as the boundary surface X described in the first embodiment.
Is divided into a first inner stiffener portion 33 located radially outward and a second inner stiffener portion 34 located radially inner, and the first inner stiffener portion 33 has a Shore A hardness of 58 degrees to 68 degrees. On the other hand, the second inner stiffener portion 34 is made of rubber and has a Shore A hardness of 75 degrees or more.

【００１５】図４はこの発明の第３実施例を示す図であ
る。この実施例においては、境界面Ｄは軸方向外側端部
が折返し部16の半径方向外側端23より半径方向内側のビ
ードコア12近傍に位置しているが、スティフナー20の厚
さ方向中央部で折れ曲がりほぼ半径方向外側に向かって
延びている。そして、外側スティフナー部36はこの境界
面Ｄの軸方向外側端部の半径方向外側に位置しており、
一方、内側スティフナー部37はこの境界面Ｄの軸方向外
側端部の半径方向内側およびほぼ半径方向外側に延びて
いる境界面Ｄの軸方向内側に位置している。また、この
実施例では、前記内側スティフナー部37は境界面Ｄの軸
方向外側端部の延長線上に位置する境界面Ｅによって、
半径方向外側に位置する第１内側スティフナー部38と、
半径方向内側に位置する第２内側スティフナー部39とに
区分され、第１内側スティフナー部38はショアＡ硬度が
58度から68度のゴムから、一方、第２内側スティフナー
部39はショアＡ硬度が75度以上のゴムから構成されてい
る。なお、この実施例においては、第１実施例で説明し
たカバーゴム体は設けられていない。FIG. 4 is a diagram showing a third embodiment of the present invention. In this embodiment, the boundary surface D is located at the axially outer end portion in the vicinity of the bead core 12 radially inward of the radially outer end 23 of the folding portion 16, but is bent at the center portion in the thickness direction of the stiffener 20. It extends substantially radially outward. The outer stiffener portion 36 is located radially outside the axially outer end of the boundary surface D,
On the other hand, the inner stiffener portion 37 is located on the axially inner side of the boundary surface D extending radially inward and substantially radially outward of the axially outer end portion of the boundary surface D. Further, in this embodiment, the inner stiffener portion 37 is defined by the boundary surface E located on the extension line of the axially outer end portion of the boundary surface D.
A first inner stiffener portion 38 located radially outward,
The first inner stiffener portion 38 is divided into a second inner stiffener portion 39 located radially inward, and the first inner stiffener portion 38 has a Shore A hardness.
The second inner stiffener portion 39 is made of rubber having a hardness of 58 degrees to 68 degrees, while the second inner stiffener portion 39 is made of rubber having a Shore A hardness of 75 degrees or more. The cover rubber body described in the first embodiment is not provided in this embodiment.

【００１６】図５はこの発明の第４実施例を示す図であ
る。この実施例においては、外側スティフナー部41を境
界面Ｘより半径方向外側に位置し該境界面Ｘと逆方向に
傾斜している境界面Ｆによって、半径方向外側に位置す
る第１外側スティフナー部42と半径方向内側に位置する
第２外側スティフナー部43とに区分し、第１外側スティ
フナー部42をショアＡ硬度が58度〜68度のゴムから、一
方、第２外側スティフナー部43をショアＡ硬度が56度以
下のゴムから構成している。なお、この実施例において
も、第１実施例で説明したカバーゴム体は設けられてい
ない。FIG. 5 is a diagram showing a fourth embodiment of the present invention. In this embodiment, the outer stiffener portion 41 is located radially outward of the boundary surface X, and the first outer stiffener portion 42 located radially outward is formed by the boundary surface F that is inclined in the direction opposite to the boundary surface X. And a second outer stiffener portion 43 located on the inner side in the radial direction. The first outer stiffener portion 42 is made of rubber having a Shore A hardness of 58 to 68 degrees, while the second outer stiffener portion 43 is made to have a Shore A hardness. Is composed of rubber of 56 degrees or less. Note that, also in this embodiment, the cover rubber body described in the first embodiment is not provided.

【００１７】次に、第１試験例を説明する。この試験に
当たっては、ビード部構造が同一である、即ち図６に示
すようにスティフナー51を境界面Ｇによって外側スティ
フナー部52と内側スティフナー部53とに区分した従来タ
イヤ、比較タイヤおよび供試タイヤ１、２を準備した
が、これら各タイヤの外側、内側スティフナー部52、53
のショアＡ硬度は以下の表１に示すような値である。Next, the first test example will be described. In this test, the bead structure is the same, that is, the stiffener 51 is divided into the outer stiffener part 52 and the inner stiffener part 53 by the boundary surface G as shown in FIG. 2 were prepared, but the outer and inner stiffener parts 52, 53 of each of these tires were prepared.
Shore A hardness is a value as shown in Table 1 below.

【表１】 ここで、これら各タイヤのサイズは11／70Ｒ22.5であっ
た。次に、これら各タイヤにＪＡＴＭＡ規格の正規内圧
（ 8kg/cm2）を充填し、同規格の正規荷重の 250％の荷
重を負荷しながらドラム上を時速60kmでビード部にセパ
レーションに基づく故障が発生するまで走行させた。そ
して、従来タイヤの走行距離を 100として各タイヤの走
行距離を表１に指数で示した。この表１から明らかなよ
うに外側スティフナー部52のショアＡ硬度が56度以下で
あると、ビード部耐久性が確実に向上する。[Table 1] Here, the size of each of these tires was 11 / 70R22.5. Next, each of these tires was filled with JATMA standard internal pressure (8 kg / cm 2 ) and a load of 250% of the standard standard load was applied on the drum at a speed of 60 km per hour due to separation due to separation at the bead. It was run until it occurred. Then, the mileage of each tire is shown as an index in Table 1, assuming that the mileage of the conventional tire is 100. As is clear from Table 1, when the Shore A hardness of the outer stiffener portion 52 is 56 degrees or less, the durability of the bead portion is surely improved.

【００１８】次に、第２試験例を説明する。この試験に
当たっては、前記第１試験例で用いた従来タイヤと、ビ
ード部が図１、２に示すような構造の供試タイヤ３、４
と、ビード部が図３に示すような構造の供試タイヤ５
と、ビード部が図４に示すような構造の供試タイヤ６
と、ビード部が図５に示すような構造の供試タイヤ７
と、を準備したが、これら各タイヤの外側、内側スティ
フナー部のショアＡ硬度およびカバーゴム体のショアＡ
硬度は以下の表２に示すような値である。Next, a second test example will be described. In this test, the conventional tire used in the first test example and the test tires 3 and 4 each having a bead structure as shown in FIGS.
And the test tire 5 having a bead structure as shown in FIG.
And a test tire 6 having a bead structure as shown in FIG.
And the test tire 7 having a bead structure as shown in FIG.
, And the shore A hardness of the outer and inner stiffeners of each of these tires and the shore A of the cover rubber body.
The hardness is a value as shown in Table 2 below.

【表２】 ここで、これら各タイヤのサイズは前述と同様に11／70
Ｒ22.5であった。次に、これら各タイヤにＪＡＴＭＡ規
格の正規内圧（ 8kg/cm2）を充填し、同規格の正規荷重
の 250％の荷重を負荷しながらドラム上を時速60kmでビ
ード部にセパレーションに基づく故障が発生するまで走
行させた。そして、従来タイヤの走行距離を 100として
各タイヤの走行距離を表２に指数で示した。この表２か
ら明らかなように、いずれのビード部構造のタイヤにお
いてもビード部耐久性が向上し、しかも、シートゴム体
を設けたタイヤではビード部耐久性がさらに向上してい
る。[Table 2] Here, the size of each of these tires is 11/70 as described above.
It was R22.5. Next, each of these tires was filled with JATMA standard internal pressure (8 kg / cm 2 ) and a load of 250% of the standard standard load was applied on the drum at a speed of 60 km per hour due to separation due to separation at the bead. It was run until it occurred. Then, the mileage of each tire is shown as an index in Table 2 with the mileage of the conventional tire as 100. As is apparent from Table 2, the bead portion durability is improved in any bead portion structure tire, and further, the bead portion durability is further improved in the tire provided with the sheet rubber body.

【００１９】なお、この発明においては、折返し部16の
軸方向外側に非伸長性コードが埋設されたチェーファー
を、その半径方向外側端が折り返し部16の半径方向外側
端23より半径方向外側になるよう密着配置してもよく、
この場合にはこれらチェーファーが外側プライとなる。In the present invention, the chafer in which the non-stretchable cord is embedded on the axially outer side of the folded-back portion 16 has the radially outer end located radially outward of the radially outer end 23 of the folded-back portion 16. May be placed closely so that
In this case, these chafers are the outer plies.

【００２０】[0020]

【発明の効果】以上説明したように、この発明によれ
ば、ビード部における発熱および転がり抵抗の増大を防
止しながら、外側プライの半径方向外側端近傍における
セパレーションを抑制する。As described above, according to the present invention, the heat generation and the increase in rolling resistance at the bead portion are prevented, and the separation near the radially outer end of the outer ply is suppressed.

【図面の簡単な説明】[Brief description of drawings]

【図１】この発明の第１実施例を示す空気入りタイヤの
子午線断面図である。FIG. 1 is a meridian sectional view of a pneumatic tire showing a first embodiment of the present invention.

【図２】ビード部近傍の拡大断面図である。FIG. 2 is an enlarged cross-sectional view near a bead portion.

【図３】この発明の第２実施例を示すビード部近傍の拡
大断面図である。FIG. 3 is an enlarged cross-sectional view near a bead portion showing a second embodiment of the present invention.

【図４】この発明の第３実施例を示すビード部近傍の拡
大断面図である。FIG. 4 is an enlarged sectional view of the vicinity of a bead portion showing a third embodiment of the present invention.

【図５】この発明の第４実施例を示すビード部近傍の拡
大断面図である。FIG. 5 is an enlarged cross-sectional view near a bead portion showing a fourth embodiment of the present invention.

【図６】試験に用いた空気入りタイヤのビード部近傍を
示す拡大断面図である。FIG. 6 is an enlarged cross-sectional view showing the vicinity of a bead portion of a pneumatic tire used for a test.

【符号の説明】[Explanation of symbols]

11…空気入りタイヤ 12…ビードコア 13…カーカス層 15…本体部 16…外側プライ 20…スティフナー 21…外側スティフナー部 22…内側スティフナー部 23…半径方向外側端 25…カバーゴム体 Ｘ…境界面 11 ... Pneumatic tire 12 ... Bead core 13 ... Carcass layer 15 ... Body part 16 ... Outer ply 20 ... Stiffener 21 ... Outer stiffener part 22 ... Inner stiffener part 23 ... Radial outer end 25 ... Cover rubber body X ... Boundary surface

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】ほぼ半径方向に延びるカーカス層の本体部
と、前記本体部の軸方向外側に配置されるとともに該本
体部に沿って延びる外側プライと、前記本体部と外側プ
ライとの間に配置されたビードコアと、半径方向内側部
が本体部と外側プライとの間に密着配置されるととも
に、その半径方向内端がビードコアに接し、半径方向外
側部が本体部の軸方向外側に密着配置されたスティフナ
ーと、を備えた空気入りタイヤのビード部構造におい
て、前記スティフナーを、外側プライの半径方向外側端
より半径方向内側に軸方向外側端部が位置する境界面に
よって、半径方向外側に位置しショアＡ硬度が56度以下
のゴムからなる外側スティフナー部と、半径方向内側に
位置しショアＡ硬度が58度以上のゴムからなる内側ステ
ィフナー部とに区分するとともに、該外側スティフナー
部を外側プライの半径方向外側端より半径方向外側まで
延在させたことを特徴とする空気入りタイヤのビード部
構造。1. A body portion of a carcass layer extending substantially in a radial direction, an outer ply arranged axially outside the body portion and extending along the body portion, and between the body portion and the outer ply. The arranged bead core and the radially inner part are closely arranged between the body part and the outer ply, the radially inner end is in contact with the bead core, and the radially outer part is closely arranged on the outer side in the axial direction of the body part. In a bead structure for a pneumatic tire including a stiffener, the stiffener being located radially outward by a boundary surface having an axial outer end located radially inward from a radial outer end of the outer ply. It is divided into an outer stiffener part made of rubber having a Shore A hardness of 56 degrees or less and an inner stiffener part made of rubber having a Shore A hardness of 58 degrees or more located radially inward. At the same time, the bead portion structure of the pneumatic tire is characterized in that the outer stiffener portion extends radially outward from an outer end of the outer ply in the radial direction. 【請求項２】前記外側プライの半径方向外側端の周囲を
ショアＡ硬度が外側スティフナー部より高いカバーゴム
体によって局部的に囲むようにした請求項１記載の空気
入りタイヤのビード部構造。2. The bead structure for a pneumatic tire according to claim 1, wherein a periphery of the radially outer end of the outer ply is locally surrounded by a cover rubber body having a Shore A hardness higher than that of the outer stiffener portion.
JP33789594A 1994-12-27 1994-12-27 Bead part structure of pneumatic tire Pending JPH08175130A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP33789594A JPH08175130A (en) 1994-12-27 1994-12-27 Bead part structure of pneumatic tire

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP33789594A JPH08175130A (en) 1994-12-27 1994-12-27 Bead part structure of pneumatic tire

Publications (1)

Publication Number Publication Date
JPH08175130A true JPH08175130A (en) 1996-07-09

Family

ID=18313016

Family Applications (1)

Application Number Title Priority Date Filing Date
JP33789594A Pending JPH08175130A (en) 1994-12-27 1994-12-27 Bead part structure of pneumatic tire

Country Status (1)

Country Link
JP (1) JPH08175130A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130192737A1 (en) * 2009-12-09 2013-08-01 Michelin Recherche Et Technique S.A. Tire bead for a heavy civil engineering vehicle

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130192737A1 (en) * 2009-12-09 2013-08-01 Michelin Recherche Et Technique S.A. Tire bead for a heavy civil engineering vehicle
US8960253B2 (en) * 2009-12-09 2015-02-24 Compagne Generale Des Etablissements Michelin Tire bead for a heavy civil engineering vehicle

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