JP2007153318A - Tire for heavy load - Google Patents

Tire for heavy load Download PDF

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JP2007153318A
JP2007153318A JP2006291543A JP2006291543A JP2007153318A JP 2007153318 A JP2007153318 A JP 2007153318A JP 2006291543 A JP2006291543 A JP 2006291543A JP 2006291543 A JP2006291543 A JP 2006291543A JP 2007153318 A JP2007153318 A JP 2007153318A
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rubber
bead
tire
ply
piece
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JP4843454B2 (en
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Kiyoto Maruoka
清人 丸岡
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Sumitomo Rubber Industries Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To ensure bead durability to a high degree while accomplishing light weight by making a bead part thin. <P>SOLUTION: In the tire of a bead wind structure, a U-shaped bead reinforcement layer 15 is provided on the bead part 4. On an outer end Pe in a radial direction of an outer piece 15o of the bead reinforcement layer 15, an inner rubber 20 includes a low elasticity rubber part 21 of complex modulus of elasticity of 3.0-6.0 MPa. Thickness Ti of the inner rubber 20 on a first reference line X1 passing through the outer end Pe and perpendicular to a ply body part 6a is made to 7.0-13.0 mm and a ratio ti/Ti to the thickness ti of the low elasticity rubber part 21 on the reference line X1 is made to 0.9 or higher. Further, an outer rubber 30 includes a low elasticity rubber part 31 of complex modulus of elasticity of 3.0-6.0 MPa. Thickness To of the outer rubber 30 on a second reference line X2 passing through the outer end Pe and perpendicular to a tire outer surface TS is made to 5.0-11.0 mm and a ratio to/To to the thickness to of the low elasticity rubber part 31 on the reference line X2 is made to 0.4 or higher. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、ビードワインド構造において、ビード部をスリム化し軽量化を図りながらビード耐久性を確保した重荷重用タイヤに関する。   The present invention relates to a heavy-duty tire having a bead wind structure in which bead durability is ensured while slimming a bead portion to reduce weight.

近年、図5に示すように、タイヤの骨格をなすカーカスプライaのプライ折返し部a1を、ビードコアbの周りで略一周巻した所謂ビードワインド構造のタイヤが提案されている(例えば特許文献1参照)。   In recent years, as shown in FIG. 5, a tire having a so-called bead wind structure in which a ply turn-up portion a1 of a carcass ply a that forms a skeleton of a tire is wound around a bead core b has been proposed (see, for example, Patent Document 1). ).

この構造は、前記プライ折返し部a1がビードコアbの近傍で途切れるため、その先端a1eにビード変形時の応力がほとんど作用せず、該先端a1eを起点とした損傷を効果的に抑制できる。しかもプライ折返し部a1の長さが小であるため、タイヤの軽量化にも貢献しうるという利点がある。そして、このビードワインド構造のタイヤにおいても、ビード部のゴムボリュームを減じてスリム化し、さらなる軽量化を図ることが強く望まれる。   In this structure, since the ply turn-up portion a1 is interrupted in the vicinity of the bead core b, the stress at the time of bead deformation hardly acts on the tip a1e, and damage starting from the tip a1e can be effectively suppressed. Moreover, since the length of the ply turn-back portion a1 is small, there is an advantage that it can contribute to weight reduction of the tire. And also in this bead wind structure tire, it is strongly desired to reduce the rubber volume of the bead portion for slimming and further weight reduction.

特開2005−170145号公報JP 2005-170145 A

しかしこのビードワインド構造では、従来的な非ビードワインド構造のものに比して、接地時のビード変形が比較的大である。そのため、ビード部をU字状に折り返して補強するビード補強層cの外片c1の外端部c1eにおいて、剪断力が大きく作用し、この外端部c1eで損傷を招きやすいという問題がある。この剪断力は、前記外端部c1eにおけるビード部のゴムボリュームを増し歪みを減じることで低減できるが、斯かる場合には重量増加を招くなど、耐久性と軽量化との両立を困難なものとしていた。   However, in this bead wind structure, the bead deformation at the time of grounding is relatively large as compared with the conventional non-bead wind structure. Therefore, there is a problem in that the outer end portion c1e of the outer piece c1 of the bead reinforcement layer c that reinforces the bead portion by folding it back in a U-shape exerts a large shearing force, and damage is easily caused at the outer end portion c1e. This shearing force can be reduced by increasing the rubber volume of the bead portion at the outer end c1e and reducing the distortion. In such a case, it is difficult to achieve both durability and light weight, such as increasing the weight. I was trying.

このような状況に鑑み、本発明者は、ビードワインド構造のタイヤについてさらに研究を行った。その結果、前記外片c1の外端部c1eにおける、カーカスプライ本体部a2と外片c1との間の内側ゴムgi、及び外片c1とタイヤ外側面との間の外側ゴムgoに低弾性のゴムを用いて柔軟にすることで、前記内側ゴムgiの厚さを減じてスリム化した場合にも、前記外端部c1eを起点とした損傷を抑制でき、ビード耐久性を確保しうることを究明し得た。   In view of such a situation, the present inventor has further studied a tire having a bead wind structure. As a result, the inner rubber gi between the carcass ply main body a2 and the outer piece c1 and the outer rubber go between the outer piece c1 and the tire outer surface at the outer end c1e of the outer piece c1 have low elasticity. By making it flexible using rubber, even when the inner rubber gi is reduced in thickness and slimmed, damage starting from the outer end c1e can be suppressed, and bead durability can be secured. It was possible to investigate.

そこで本発明は、前記ビードワインド構造において、ビード部をスリム化して軽量化を図りながらもビード耐久性を確保しうる重荷重用タイヤを提供することを目的としている。   Therefore, an object of the present invention is to provide a heavy-duty tire capable of ensuring bead durability while reducing the weight by slimming the bead portion in the bead wind structure.

本願請求項1の発明は、トレッド部からサイドウォール部をへてビード部のビードコアに至るプライ本体部と、該プライ本体部に連なりかつ前記ビードコアの廻りをタイヤ軸方向内側から外側に折り返されたプライ折返し部とを有する1枚のカーカスプライからなるカーカスを具えた重荷重用タイヤであって、
前記プライ折返し部は、ビードコアのタイヤ軸方向内側の内の側面とタイヤ半径方向内側の内面とタイヤ軸方向外側の外の側面とに沿って湾曲する主部、及び該主部に連なり前記ビードコアのタイヤ半径方向外側の外面の近傍を前記プライ本体部に向かって傾斜してのびる副部からなり、
かつ前記ビード部に、前記プライ折返し部の主部に沿いその半径方向内方を通る曲線状部と、この曲線状部のタイヤ軸方向外側で前記主部と離れて半径方向外方に向かってタイヤ軸方向外側に傾斜する外片と、前記曲線状部のタイヤ軸方向内側で前記プライ本体部のタイヤ軸方向内側面に沿ってのびる内片とからなるビード補強層を設け、
しかも前記外片の半径方向外端から、ビードベースラインまでの半径方向高さを25〜40mm、かつ前記ビードコアの外面から5mmの距離を隔たるプライ本体部上の点Pjから、前記外片までの距離を14〜20mmとするとともに、
前記外片の半径方向外端において、前記プライ本体部と外片との間に介在する内側ゴムは、複素弾性率E* 1が3.0〜6.0MPaの低弾性ゴムからなりかつ前記外片に隣接する低弾性ゴム部を含み、しかも前記外片の半径方向外端を通りプライ本体部に直交する第1の基準線における前記内側ゴムの厚さTiを7.0〜13.0mm、かつ該第1の基準線における前記低弾性ゴム部の厚さtiとの比ti/Tiを0.9以上とする一方、
前記外片の半径方向外端において、前記外片とタイヤ外側面と間に介在する外側ゴムは、複素弾性率E* 2が3.0〜6.0MPaの低弾性ゴムからなりかつ前記外片に隣接する低弾性ゴム部を含み、しかも前記外片の半径方向外端を通りタイヤ外側面に直交する第2の基準線における前記外側ゴムの厚さToを5.0〜11.0mm、かつ該第2の基準線における前記低弾性ゴム部の厚さtoとの比to/Toを0.4以上としたことを特徴としている。
In the invention of claim 1 of the present application, a ply body part extending from the tread part through the sidewall part to the bead core of the bead part, the ply body part connected to the ply body part, and the circumference of the bead core folded back from the inner side in the tire axial direction. A heavy duty tire having a carcass made of a single carcass ply having a ply turn-up portion,
The ply folded portion includes a main portion that curves along an inner side surface of the bead core in the tire axial direction inner side, an inner surface in the tire radial direction inner side, and an outer side surface in the tire axial direction outer side, and the main portion that is connected to the main portion. Consists of a sub-portion extending near the outer surface of the outer side in the tire radial direction toward the ply body,
And a curved portion passing through the inner portion in the radial direction along the main portion of the ply turn-up portion in the bead portion, and away from the main portion on the outer side in the tire axial direction of the curved portion toward the outer side in the radial direction. A bead reinforcement layer is provided that includes an outer piece that is inclined outward in the tire axial direction, and an inner piece that extends along the tire axial direction inner side surface of the ply main body portion on the inner side in the tire axial direction of the curved portion,
In addition, the height in the radial direction from the radially outer end of the outer piece to the bead base line is 25 to 40 mm, and the point Pj on the ply main body that is 5 mm away from the outer surface of the bead core to the outer piece. And the distance of 14-20 mm,
An inner rubber interposed between the ply main body portion and the outer piece at a radially outer end of the outer piece is made of a low elastic rubber having a complex elastic modulus E * 1 of 3.0 to 6.0 MPa and the outer rubber. A thickness of the inner rubber at a first reference line including a low elastic rubber portion adjacent to the piece and passing through the radially outer end of the outer piece and perpendicular to the ply main body portion is 7.0 to 13.0 mm; And the ratio ti / Ti with respect to the thickness ti of the low elastic rubber part at the first reference line is 0.9 or more,
The outer rubber interposed between the outer piece and the outer surface of the tire at the radially outer end of the outer piece is made of a low elastic rubber having a complex elastic modulus E * 2 of 3.0 to 6.0 MPa, and the outer piece. And a thickness To of the outer rubber at a second reference line that passes through the radially outer end of the outer piece and is orthogonal to the outer surface of the tire, and 5.0 to 11.0 mm, and A ratio to / To with respect to the thickness to of the low elastic rubber portion at the second reference line is set to 0.4 or more.

又請求項2の発明では、前記内側ゴムは、前記プライ本体部と前記外片との間を通って前記副部から半径方向外側にのびる断面三角形状のビードエーペックスゴムからなり、かつ前記外側ゴムは、少なくともビードベースラインから前記外片のタイヤ軸方向外側を通って半径方向外側にのびるリムずれ防止用のクリンチゴムからなることを特徴としている。
又請求項3の発明では、前記内側ゴムの低弾性ゴム部の複素弾性率E* 1と、前記外側ゴムの低弾性ゴム部の複素弾性率E* 2との差|E* 1−E* 2|は、3.0MPa以下であることを特徴としている。
又請求項4の発明では、前記ビードエーペックスゴムは、前記低弾性ゴム部のみからなることを特徴としている。
又請求項5の発明では、前記内側ゴムの厚さTiと外側ゴムの厚さToとの比To/Tiは0.6〜0.9であることを特徴としている。
According to a second aspect of the present invention, the inner rubber is composed of a bead apex rubber having a triangular cross section that extends between the ply main body part and the outer piece and extends radially outward from the sub part, and the outer rubber. Is characterized by comprising clinching rubber for preventing rim displacement extending at least from the bead base line through the outer side in the tire axial direction of the outer piece and radially outward.
In the invention of claim 3, the difference between the complex elastic modulus E * 1 of the low elastic rubber portion of the inner rubber and the complex elastic modulus E * 2 of the low elastic rubber portion of the outer rubber | E * 1-E * 2 | is characterized by being 3.0 MPa or less.
According to a fourth aspect of the present invention, the bead apex rubber includes only the low elastic rubber portion.
In the invention of claim 5, the ratio To / Ti of the thickness Ti of the inner rubber and the thickness To of the outer rubber is 0.6 to 0.9.

本明細書では、特に断りがない限り、タイヤの各部の寸法等は、タイヤを正規リムにリム組しかつ50kPaの内圧を充填した無負荷の50kPa充填状態において特定される値とする。なお前記「正規リム」とは、タイヤが基づいている規格を含む規格体系において、当該規格がタイヤ毎に定めるリムであり、例えばJATMAであれば標準リム、TRAであれば "Design Rim" 、或いはETRTOであれば "Measuring Rim"を意味する。   In this specification, unless otherwise specified, the dimensions and the like of each part of the tire are values specified in an unloaded 50 kPa filling state in which the tire is rim-assembled with a normal rim and filled with an internal pressure of 50 kPa. The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based, for example, a standard rim for JATMA, “Design Rim” for TRA, or ETRTO means "Measuring Rim".

又複素弾性率は、粘弾性スペクトロメーターを用い、温度70℃、周波数10Hz、初期歪10%、動歪±1%として測定した値としている。   The complex elastic modulus is a value measured using a viscoelastic spectrometer as a temperature of 70 ° C., a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of ± 1%.

本発明は叙上の如く構成しているため、後述する理由によって、ビードワインド構造において、ビード部をスリム化して軽量化を図りながらも優れたビード耐久性を確保することが可能となる。   Since the present invention is configured as described above, for the reasons described later, in the bead wind structure, it is possible to ensure excellent bead durability while slimming the bead portion and reducing the weight.

以下、本発明の実施の一形態を、図示例とともに説明する。図1は、本願発明の重荷重用タイヤの50kPa充填状態を示す断面図である。   Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a 50 kPa filling state of the heavy duty tire of the present invention.

図1において、重荷重用タイヤ1は、トレッド部2からサイドウォール部3をへてビード部4のビードコア5に至るカーカス6と、このカーカス6の半径方向外側かつトレッド部2の内方に配されるベルト層7とを具える。   In FIG. 1, a heavy load tire 1 is disposed on a carcass 6 that extends from a tread portion 2 to a bead core 5 of a bead portion 4 through a sidewall portion 3, and on the radially outer side of the carcass 6 and on the inner side of the tread portion 2. Belt layer 7.

前記ベルト層7は、スチール製のベルトコードを用いた複数枚(重荷重用タイヤの場合は通常3枚以上)のベルトプライから形成される。本例では、前記ベルトコードをタイヤ周方向に対して例えば60±15°の角度で配列した半径方向最内側の第1のベルトプライ7Aと、タイヤ周方向に対して例えば10〜35°の小角度で配列した第2〜4のベルトプライ7B〜7Dとの4枚構造をなすものを例示している。このベルトプライ7A〜7Dは、ベルトコードがプライ間で互いに交差する箇所を1箇所以上設けて重置されることにより、ベルト剛性を高めトレッド部2をタガ効果を有して補強している。   The belt layer 7 is formed of a plurality of belt plies (usually three or more in the case of heavy duty tires) using steel belt cords. In this example, the innermost first belt ply 7A in the radial direction in which the belt cord is arranged at an angle of 60 ± 15 °, for example, with respect to the tire circumferential direction, and a small size of, for example, 10 to 35 ° with respect to the tire circumferential direction. An example of a four-sheet structure with second to fourth belt plies 7B to 7D arranged at an angle is illustrated. The belt plies 7 </ b> A to 7 </ b> D are provided with one or more places where the belt cords cross each other between the plies, and are superposed to enhance belt rigidity and reinforce the tread portion 2 with a tagging effect.

前記カーカス6は、スチール製のカーカスコードをタイヤ周方向に対して75〜90°の角度で配列した一枚のカーカスプライ6Aから形成される。このカーカスプライ6Aは、前記ビードコア5、5間を跨るプライ本体部6aの両側に、前記ビードコア5の廻りでタイヤ軸方向内側から外側に折り返されるプライ折返し部6bを一連に具える。   The carcass 6 is formed of a single carcass ply 6A in which steel carcass cords are arranged at an angle of 75 to 90 ° with respect to the tire circumferential direction. The carcass ply 6A includes a series of ply turn-up portions 6b that are turned back from the inner side in the tire axial direction around the bead core 5 on both sides of the ply main body portion 6a straddling the bead cores 5 and 5.

又前記ビードコア5は、図2に拡大して示すように、例えばスチール製のビードワイヤ5wを多段多列に巻回してなるリング状体であって、本例では、断面横長の偏平六角形状のものを例示する。ビードコア5の断面形状としては、必要に応じて、偏平矩形状も採用できる。断面が六角形状のビードコア5については、その横断面において、タイヤ半径方向内側の長片を形成する面をビードコア5の内面SLとし、タイヤ半径方向外側の長辺を形成する面をビードコア5の外面SUとする。またビードコア5の前記内面SLと前記外面SUとの間をタイヤ軸方向内側で継ぐ折れ線状の屈曲辺を形成する面をビードコア5の内の側面Siとし、反対側の屈曲辺を形成する面を外の側面Soとする。前記内面SLは、正規リムJ(図3に示す)のリムシートJ1のシート面と略平行にのび、これによりリムとの嵌合力を広範囲に亘って高める。又前記正規リムJは、チューブレス用の15°テーパーリムであり、従って、ビードコア5の前記内外面SL、SUは、タイヤ軸方向線に対して略15°の角度で傾斜する。なお「略15°」とは、製造時の誤差を許容するものであり、15°±2゜の範囲を意味する。   The bead core 5 is a ring-shaped body in which, for example, steel bead wires 5w are wound in multiple stages and multiple rows, as shown in an enlarged view in FIG. Is illustrated. As the cross-sectional shape of the bead core 5, a flat rectangular shape can be adopted as necessary. Regarding the bead core 5 having a hexagonal cross section, in the cross section thereof, the surface forming the long piece on the inner side in the tire radial direction is the inner surface SL of the bead core 5, and the surface forming the long side on the outer side in the tire radial direction is the outer surface of the bead core 5 Let it be SU. Further, a surface that forms a bent line-shaped bent side that connects the inner surface SL and the outer surface SU of the bead core 5 on the inner side in the tire axial direction is defined as a side surface Si in the bead core 5 and a surface that forms the opposite bent side. Let it be the outer side surface So. The inner surface SL extends substantially parallel to the seat surface of the rim sheet J1 of the regular rim J (shown in FIG. 3), thereby increasing the fitting force with the rim over a wide range. The regular rim J is a tubeless 15 ° taper rim. Therefore, the inner and outer surfaces SL and SU of the bead core 5 are inclined at an angle of approximately 15 ° with respect to the tire axial direction line. Note that “approximately 15 °” allows an error during manufacture, and means a range of 15 ° ± 2 °.

次に、本実施形態のタイヤ1は、カーカス6の前記プライ折返し部6bが、ビードコア5の周面に巻き付けられたビードワインド構造を具える。   Next, the tire 1 of the present embodiment includes a bead wind structure in which the ply turn-up portion 6 b of the carcass 6 is wound around the peripheral surface of the bead core 5.

詳しくは、前記プライ折返し部6bは、図2に示すように、ビードコア5の前記内の側面Si、内面SL、及び外の側面Soに沿って湾曲する主部10と、該主部10に連なりビードコアの前記外面SUの近傍を前記プライ本体部6aに向かって傾斜してのびる副部11とから構成される。   Specifically, as shown in FIG. 2, the ply turn-up portion 6 b is connected to the main portion 10 that is curved along the inner side surface Si, the inner surface SL, and the outer side surface So of the bead core 5. The bead core includes a sub-part 11 that extends in the vicinity of the outer surface SU toward the ply body 6a.

前記副部11は、ビードコア5の前記外面SU(又はその延長線)よりも半径方向外側の部位を意味し、前記外面SUとの距離が先端11aに向かって増加する向きに傾斜している。そして、前記副部11と前記外面SUとの間には、断面略三角状の充填ゴム13を配設している。ここで前記副部11の前記外面SUに対する角度θは、10°以上さらには15°以上が好ましく、これによりカーカスコードの曲がりの度合いを適度に緩和し、該コードのスプリングバックに起因する空気残りなどの成形不良を抑制する。なお前記角度θが大きすぎると、プライ折返し部6bの係止力が弱まり、所謂吹き抜け現象が生じる恐れを招く。そのために、前記角度θの上限は60°以下、さらには45°以下とするのが好ましい。   The sub-portion 11 means a portion radially outward from the outer surface SU (or an extension thereof) of the bead core 5, and is inclined in a direction in which the distance from the outer surface SU increases toward the tip 11a. A filling rubber 13 having a substantially triangular cross section is disposed between the sub part 11 and the outer surface SU. Here, the angle θ of the sub-portion 11 with respect to the outer surface SU is preferably 10 ° or more, more preferably 15 ° or more, thereby moderately reducing the degree of bending of the carcass cord, and remaining air due to the spring back of the cord. Suppress molding defects such as. If the angle θ is too large, the locking force of the ply turn-up portion 6b is weakened, so that a so-called blow-through phenomenon may occur. Therefore, the upper limit of the angle θ is preferably 60 ° or less, more preferably 45 ° or less.

このとき、前記副部11の先端11aの前記外面SUからの距離Laは3〜10mmの範囲であるのが好ましい。前記距離Laが3mm未満では、カーカスコードの曲がりの度合いを充分緩和できない。しかも接地の際に前記副部11の先端11aに受ける衝撃が大きくなるため、該先端11aに損傷が発生しやすくなる。逆に、距離Laが10mmを超えても、前記先端11aにタイヤ変形時の応力が強く作用する傾向となるため、該先端11aに損傷が生じやすくなる。又前記先端11aのプライ本体部6aからの距離Lbは、前記先端11aがプライ本体部6aと接触してフレッティングを生じないよう1.0mm以上確保するのが好ましい。   At this time, the distance La from the outer surface SU of the tip 11a of the sub-part 11 is preferably in the range of 3 to 10 mm. If the distance La is less than 3 mm, the degree of bending of the carcass cord cannot be sufficiently eased. Moreover, since the impact received on the tip 11a of the sub-part 11 during the grounding is increased, the tip 11a is likely to be damaged. On the other hand, even when the distance La exceeds 10 mm, stress at the time of tire deformation tends to act strongly on the tip 11a, so that the tip 11a is easily damaged. The distance Lb of the tip 11a from the ply body 6a is preferably 1.0 mm or more so that the tip 11a does not come into contact with the ply body 6a to cause fretting.

又前記角度θは、前記プライ折返し部6bがビードコア5の前記外面SU(又はその延長線)に交わる副部11の下端11bと前記先端11aとを結ぶ直線の前記外面SUに対する角度として定義する。又ビードコア5では、ビードワイヤ5wが一直線状に整一せずに上下にバラツキながら配列するなど、その外面SUが非平面をなす場合がある。係る場合には、前記外面SUに現れるビードワイヤ列のうち最もタイヤ軸方向外側に位置するビードワイヤ5woと最もタイヤ軸方向内側に位置するビードワイヤ5wiとに接する接線Kで近似する。なお前記内面SL、側面Si、側面Soも同様、各面に現れるビードワイヤ列のうちで両側に位置するビードワイヤ、即ち多角形形状の各角部に位置するビードワイヤに接する接線で近似する。   The angle θ is defined as an angle with respect to the outer surface SU of a straight line connecting the lower end 11b of the sub-portion 11 where the ply turn-up portion 6b intersects the outer surface SU (or an extension thereof) of the bead core 5 and the tip 11a. Further, in the bead core 5, the outer surface SU may be non-planar, for example, the bead wires 5w are not aligned in a straight line but are arranged in a vertical manner. In such a case, the bead wire sequence appearing on the outer surface SU is approximated by a tangent line K in contact with the bead wire 5wo located on the outermost side in the tire axial direction and the bead wire 5wi located on the innermost side in the tire axial direction. Similarly, the inner surface SL, the side surface Si, and the side surface So are approximated by bead wires located on both sides of the bead wire array appearing on each surface, that is, tangent lines that are in contact with the bead wires located at each corner of the polygonal shape.

又前記充填ゴム13は、衝撃ないし応力緩和効果に優れた低弾性のゴム組成物により構成される。これにより前記副部11の先端11aでの歪みを吸収し、損傷を防ぐのに役立つ。具体的には、複素弾性率E* 3が5〜15MPaのゴム組成物が好適である。前記複素弾性率E* 3が5MPa未満の場合、該ゴムが過度に柔らかくなって前記先端11aの歪が大きくなる傾向があり、逆に15MPaを超えると、充填ゴム13の柔軟性に欠け、歪みの緩和吸収能力が低下する。このような観点より、前記複素弾性率E* 3の下限値を6MPa以上、さらには7MPa以上とするのが好ましく、又上限値を13MPa以下、されには11MPa以下とするのが好ましい。   The filled rubber 13 is composed of a low-elasticity rubber composition excellent in impact or stress relaxation effect. This absorbs distortion at the tip 11a of the sub-part 11 and helps to prevent damage. Specifically, a rubber composition having a complex elastic modulus E * 3 of 5 to 15 MPa is preferable. When the complex elastic modulus E * 3 is less than 5 MPa, the rubber tends to be excessively soft and the tip 11a tends to have a large strain. Conversely, when the complex elastic modulus E * 3 exceeds 15 MPa, the filled rubber 13 lacks the flexibility and strain. Reduces the ability to absorb and relax. From such a viewpoint, the lower limit value of the complex elastic modulus E * 3 is preferably 6 MPa or more, more preferably 7 MPa or more, and the upper limit value is preferably 13 MPa or less, and more preferably 11 MPa or less.

又ビードワインド構造では、非ビードワインド構造の従来的なタイヤに比してビード剛性が小であるため、コーナリングパワーに劣る傾向がある。そこでビード部4に、ビード補強層15を設けビード剛性を向上している。このビード補強層15は、スチールコードをタイヤ周方向線に対して例えば15〜60゜の角度で配列したコードプライからなり、図3に示すように、前記プライ折返し部6bの主部10に沿いその半径方向内方を通る曲線状部15Aと、この曲線状部15Aのタイヤ軸方向外側で前記主部10と離れて半径方向外方に向かってタイヤ軸方向外側に傾斜する外片15oと、前記曲線状部15Aのタイヤ軸方向内側で前記プライ本体部6aのタイヤ軸方向内側面に沿ってのびる内片15iとからなる断面U字状をなす。   Also, the bead wind structure has a tendency to be inferior in cornering power because the bead rigidity is smaller than that of a conventional tire having a non-bead wind structure. Therefore, a bead reinforcement layer 15 is provided in the bead portion 4 to improve bead rigidity. The bead reinforcing layer 15 is formed of a cord ply in which steel cords are arranged at an angle of, for example, 15 to 60 ° with respect to a tire circumferential direction line, and as shown in FIG. 3, along the main portion 10 of the ply turn-up portion 6b. A curved portion 15A passing inward in the radial direction, and an outer piece 15o that is inclined outward in the tire axial direction and away from the main portion 10 on the outer side in the tire axial direction of the curved portion 15A. It has a U-shaped cross section including an inner piece 15i extending along the inner side surface in the tire axial direction of the ply main body 6a on the inner side in the tire axial direction of the curved portion 15A.

ここで前記外片15oの半径方向外端PeのビードベースラインBLからの半径方向高さHoは、25〜40mmの範囲であって、25mm未満では必要な補強効果を得ることができない。しかし40mmを超えると、前記外端Peが、変形が大なサイドウォール部3側に近づきすぎとなるため、この外端Peに過度の剪断応力が集中するなどこの外端Peを起点とした損傷が発生する。なお前記内片15iでは、プライ本体部6aに隣接して保護されるため、前記外片15oに比して損傷の恐れが少なく、従って該内片15iの半径方向高さHiを前記高さHo以上に設定することができる。しかし、乗り心地性や軽量化の観点から前記高さHoよりも小に設定するのが好ましい。   Here, the radial height Ho from the bead base line BL of the radially outer end Pe of the outer piece 15o is in the range of 25 to 40 mm, and if it is less than 25 mm, the necessary reinforcing effect cannot be obtained. However, if it exceeds 40 mm, the outer end Pe becomes too close to the side wall portion 3 that is deformed so much that excessive shear stress is concentrated on the outer end Pe, and damage starting from the outer end Pe. Occurs. Since the inner piece 15i is protected adjacent to the ply body 6a, the inner piece 15i is less likely to be damaged than the outer piece 15o. Therefore, the radial height Hi of the inner piece 15i is set to the height Ho. It can be set above. However, it is preferable to set the height smaller than the height Ho from the viewpoint of ride comfort and weight reduction.

そして本発明では、前記外片15oの外端Peにおいて、
(1) 前記プライ本体部6aと外片15oとの間に介在する内側ゴム20は、複素弾性率E* 1が3.0〜6.0MPaの低弾性ゴムからなる低弾性ゴム部21を含み、しかも前記外端Peを通りプライ本体部6aに直交する第1の基準線X1における前記内側ゴムの厚さTiを7.0〜13.0mmに減じるとともに、該第1の基準線X1における前記低弾性ゴム部21の厚さtiと前記厚さTiとの比ti/Tiを0.9以上とし、
(2) 前記外片15oとタイヤ外側面TSとの間に介在する外側ゴム30は、複素弾性率E* 2が3.0〜6.0MPaの低弾性ゴムからなる低弾性ゴム部31を含み、しかも前記外端Peを通りタイヤ外側面TSに直交する第2の基準線X2における前記外側ゴムの厚さToを5.0〜11.0mm、かつ該第2の基準線X2における前記低弾性ゴム部31の厚さtoと前記厚さToとの比to/Toを0.4以上としている。
In the present invention, at the outer end Pe of the outer piece 15o,
(1) The inner rubber 20 interposed between the ply main body 6a and the outer piece 15o includes a low elastic rubber portion 21 made of low elastic rubber having a complex elastic modulus E * 1 of 3.0 to 6.0 MPa. In addition, the thickness Ti of the inner rubber at the first reference line X1 passing through the outer end Pe and orthogonal to the ply main body 6a is reduced to 7.0 to 13.0 mm, and the first reference line X1 The ratio ti / Ti between the thickness ti of the low elastic rubber portion 21 and the thickness Ti is 0.9 or more,
(2) The outer rubber 30 interposed between the outer piece 15o and the tire outer surface TS includes a low elastic rubber portion 31 made of a low elastic rubber having a complex elastic modulus E * 2 of 3.0 to 6.0 MPa. In addition, the thickness To of the outer rubber at the second reference line X2 passing through the outer end Pe and orthogonal to the tire outer surface TS is 5.0 to 11.0 mm, and the low elasticity at the second reference line X2. The ratio to / To of the thickness to of the rubber part 31 and the thickness To is set to 0.4 or more.

このとき、前記低弾性ゴム部21、31は、何れも前記外片15oに隣接して半径方向にのび、かつこの外片15oの外端Peを被覆保護している。   At this time, the low elastic rubber portions 21 and 31 both extend in the radial direction adjacent to the outer piece 15o, and cover and protect the outer end Pe of the outer piece 15o.

本例では、前記内側ゴム20は、ビードエーペックスゴム8からなるとともに、外側ゴム30は、リムずれ防止用のクリンチゴム9から構成されている。   In this example, the inner rubber 20 is made of bead apex rubber 8 and the outer rubber 30 is made of clinch rubber 9 for preventing rim displacement.

前記ビードエーペックスゴム8は、前記プライ本体部6aと前記外片15oとの間を通って前記副部11から半径方向外側に延在する断面三角形状のゴム材であり、その外端8eのビードベースラインBLからの高さHbは、前記高さHoより大に設定される。なお該高さHbは、タイヤ断面高さH(図1に示す)の40%以下とするのが、乗り心地性の観点から好ましい。又ビードエーペックスゴム8は、本例では、前記副部11の内端付近からプライ本体部6aに向かってのびる境界線jによって区分されるタイヤ軸方向内側のエーペックス部8Lと、外側のエーペックス部8Uとから形成される。そして前記外側のエーペックス部8Uを、複素弾性率E* 1が3.0〜6.0MPaの前記低弾性ゴム部21としている。なお内側のエーペックス部8Lは、本例では、複素弾性率E* 4が30〜70MPa以上の高弾性性ゴムで形成され、ビード剛性が高められる。   The bead apex rubber 8 is a rubber material having a triangular cross section that extends between the ply main body portion 6a and the outer piece 15o and extends radially outward from the auxiliary portion 11, and the bead at the outer end 8e. A height Hb from the base line BL is set to be greater than the height Ho. The height Hb is preferably 40% or less of the tire cross-section height H (shown in FIG. 1) from the viewpoint of ride comfort. In this example, the bead apex rubber 8 includes an apex portion 8L on the inner side in the tire axial direction and an outer apex portion 8U separated by a boundary line j extending from the vicinity of the inner end of the sub-portion 11 toward the ply main body portion 6a. And formed from. The outer apex portion 8U is the low elastic rubber portion 21 having a complex elastic modulus E * 1 of 3.0 to 6.0 MPa. In this example, the inner apex portion 8L is formed of a highly elastic rubber having a complex elastic modulus E * 4 of 30 to 70 MPa or more, and the bead rigidity is increased.

又前記クリンチゴム9は、ビード部4の外皮をなすリムずれ防止用のゴム部材であり、少なくともビードベースラインBLの高さ位置から、前記外片15oのタイヤ軸方向外側を通って半径方向外側に延在する。本例では、クリンチゴム9が、ビード底面をなすベース部9Lと、このベース部9Lに連なりかつタイヤ外側面TSをなすクリンチ主部9Uとからなる場合を例示する。なおクリンチ主部9Uは、前記外片15oを超えた後は、前記外側のエーペックス部8Uの外側面に隣接して半径方向外側にのび、その外端部は、サイドウォール部3の外皮をなすサイドウォールゴム3Gと接合している。なおサイドウォールゴム3Gとの接合面Sは、タイヤ外側面TSから外側のエーペックス部8Uの外側面まで、タイヤ半径方向外側に向かってのびる。   The clinching rubber 9 is a rubber member for preventing rim displacement that forms the outer skin of the bead portion 4, and at least from the height position of the bead base line BL, radially outward through the outer side in the tire axial direction of the outer piece 15 o. Extend. In this example, the case where the clinch rubber 9 includes a base portion 9L that forms the bottom surface of the bead and a clinch main portion 9U that continues to the base portion 9L and forms the tire outer surface TS is illustrated. The clinch main portion 9U extends radially outwardly adjacent to the outer surface of the outer apex portion 8U after exceeding the outer piece 15o, and the outer end portion forms the outer skin of the sidewall portion 3. Bonded to the sidewall rubber 3G. The joint surface S with the sidewall rubber 3G extends from the tire outer surface TS to the outer surface of the outer apex portion 8U toward the outer side in the tire radial direction.

又前記クリンチ主部9Uは、前記外片15oに隣接し又その外端Peを超えた後は外側のエーペックス部8Uに隣接するタイヤ軸方向内側の内側層9iと、タイヤ外側面TSをなす外側層9oとから形成される。そして、前記内側層9iを、複素弾性率E* 2が3.0〜6.0MPaの前記低弾性ゴム部31としている。なお前記内側層9iの外端のビードベースラインBLからの半径方向高さHcは、前記外片15oの高さHoの1.2〜2.0倍であるのが好ましい。又前記外側層9o及びベース部9Lは、本例では、複素弾性率E* 5が9.0〜15.0MPaの耐摩耗性に優れるゴムで形成される。   Further, the clinch main portion 9U is adjacent to the outer piece 15o and, after exceeding the outer end Pe, the outer side forming the tire outer surface TS with the inner layer 9i on the inner side in the tire axial direction adjacent to the outer apex portion 8U. And is formed from the layer 9o. The inner layer 9i is the low elastic rubber portion 31 having a complex elastic modulus E * 2 of 3.0 to 6.0 MPa. The radial height Hc from the bead base line BL at the outer end of the inner layer 9i is preferably 1.2 to 2.0 times the height Ho of the outer piece 15o. In this example, the outer layer 9o and the base portion 9L are made of rubber having excellent wear resistance with a complex elastic modulus E * 5 of 9.0 to 15.0 MPa.

このように本発明では、前記内側ゴム20の第1の基準線X1上における厚さTiを、7.0〜13.0mmの範囲とし、従来よりも減じてビード部4をスリム化することにより軽量化を図っている。このとき、前記内側ゴム20及び外側ゴム30には低弾性ゴム部21、31が設けられ、かつこの低弾性ゴム部21、31が、前記外片15o及びその外端Peを、タイヤ軸方向の内外から被覆保護する。しかも前記低弾性ゴム部21の第1の基準線X1における厚さtiを、前記内側ゴム20の全厚さTiの0.9倍以上、かつ前記低弾性ゴム部31の第2の基準線X2における厚さtoを、前記外側ゴム30の全厚さToの0.4倍以上に高めている。   As described above, in the present invention, the thickness Ti of the inner rubber 20 on the first reference line X1 is in the range of 7.0 to 13.0 mm, and the bead portion 4 is slimmed down by reducing the thickness. The weight is reduced. At this time, the inner rubber 20 and the outer rubber 30 are provided with low elastic rubber portions 21 and 31, and the low elastic rubber portions 21 and 31 connect the outer piece 15o and the outer end Pe thereof in the tire axial direction. Protect coating from inside and outside. In addition, the thickness ti of the low elastic rubber portion 21 at the first reference line X1 is 0.9 times or more the total thickness Ti of the inner rubber 20, and the second reference line X2 of the low elastic rubber portion 31. Is increased to 0.4 times or more the total thickness To of the outer rubber 30.

その結果、前記低弾性ゴム部21、31を設けたことに起因するビード変形の増大による弊害よりも、この低弾性ゴム部21、31が前記外片15o及びその外端Peを被覆保護して、前記外端Peに作用する剪断力を緩和分散させる効果の方が勝ることとなる。そのため、前記内側ゴム20の厚さTiを7.0〜13.0mmの範囲に減じてビード部4をスリム化した場合にも、前記外端Peを起点とするコードルース等の損傷を抑制することができ、ビード耐久性を高めることが可能となる。   As a result, the low elastic rubber portions 21 and 31 cover and protect the outer piece 15o and its outer end Pe, rather than the adverse effects of increased bead deformation resulting from the provision of the low elastic rubber portions 21 and 31. The effect of relaxing and dispersing the shearing force acting on the outer end Pe is superior. Therefore, even when the thickness Ti of the inner rubber 20 is reduced to a range of 7.0 to 13.0 mm and the bead portion 4 is slimmed, damage such as a cord loose starting from the outer end Pe is suppressed. And bead durability can be increased.

なお前記複素弾性率E* 1,E* 2が、3.0MPa未満では、ビード変形が大となって剪断力の増大を招き、又6.0MPaを超えても剪断力の緩和分散効果に劣るなど、何れの場合もビード耐久性の向上効果が発揮されなくなる。なお前記複素弾性率E* 1、E* 2の差|E* 1−E* 2|は、3.0MPa以下であるのが、剪断力の緩和分散効果のために好ましく、さらには複素弾性率E* 1、E* 2を等しくするのがより好ましい。   If the complex elastic modulus E * 1, E * 2 is less than 3.0 MPa, the bead deformation becomes large and the shear force increases, and if it exceeds 6.0 MPa, the effect of relaxing and dispersing the shear force is inferior. In any case, the effect of improving the bead durability is not exhibited. The difference | E * 1-E * 2 | between the complex elastic moduli E * 1 and E * 2 is preferably 3.0 MPa or less because of the effect of relaxation and dispersion of the shear force. It is more preferable to make E * 1 and E * 2 equal.

又内側ゴム20の前記厚さTiが7.0mm未満、及び外側ゴム30の前記厚さToが5.0mm未満では、ビード変形が過大となって、低弾性ゴム部21、31を用いた場合にもビード耐久性の向上が見込めず、又操縦安定性にも不利となる。又前記厚さTiが13.0mmより大、及び前記厚さToが11.0mmより大では、軽量化が達成されない。このような観点から前記厚さTiでは、その下限値を9.0mm以上、上限値を15.0mm以下とするのがより好ましく、又前記厚さToでは、その下限値を10.0mm以上、上限値を13.0mm以下とするのがより好ましい。   When the thickness Ti of the inner rubber 20 is less than 7.0 mm and the thickness To of the outer rubber 30 is less than 5.0 mm, the bead deformation becomes excessive and the low elastic rubber portions 21 and 31 are used. However, the improvement of the bead durability is not expected, and the handling stability is disadvantageous. If the thickness Ti is greater than 13.0 mm and the thickness To is greater than 11.0 mm, weight reduction cannot be achieved. From such a viewpoint, in the thickness Ti, it is more preferable that the lower limit value is 9.0 mm or more and the upper limit value is 15.0 mm or less. In the thickness To, the lower limit value is 10.0 mm or more, The upper limit value is more preferably 13.0 mm or less.

又前記厚さの比ti/Tiが0.9未満、及び比to/Toが0.4未満では、剪断力の緩和分散効果が不充分となってビード耐久性の向上が達成できなくなる。前記比ti/Tiの上限値は1.0であり、例えば、内側のエーペックス部8Lを前記第1の基準線X1よりも半径方向内側に控えて形成することにより、前記比ti/Tiを1.0とすることもでき、又外側のエーペックス部8Uのみでビードエーペックスゴム8を形成することにより、前記比ti/Tiを1.0とすることもできる。   On the other hand, if the thickness ratio ti / Ti is less than 0.9 and the ratio to / To is less than 0.4, the effect of relaxation and dispersion of the shearing force is insufficient, and the improvement of the bead durability cannot be achieved. The upper limit value of the ratio ti / Ti is 1.0. For example, the ratio ti / Ti is set to 1 by forming the inner apex portion 8L so as to be radially inward from the first reference line X1. The ratio ti / Ti can also be set to 1.0 by forming the bead apex rubber 8 only with the outer apex portion 8U.

又前記厚さの比to/Toの上限値は、0.9以下が好ましい。   The upper limit of the thickness ratio to / To is preferably 0.9 or less.

又前記内側ゴムの厚さTiと外側ゴムの厚さToとの比To/Tiを0.6〜0.9の範囲とするのが好ましく、これにより、外片15oの外端Peが曲げ変形時の応力の中立線に近づくため、外端Peに作用する応力を軽減するのに役立つ。   The ratio To / Ti of the inner rubber thickness Ti and the outer rubber thickness To is preferably in the range of 0.6 to 0.9, whereby the outer end Pe of the outer piece 15o is bent and deformed. Since it approaches the neutral line of the stress at time, it helps to reduce the stress acting on the outer end Pe.

又本実施形態のタイヤ1では、前記ビードコア5の外面SUから5mmの距離を隔たるプライ本体部6a上の点Pjから、前記外片15oまでの距離Wが14〜20mmの範囲である。この距離Wが14mm未満では、ビード剛性が過小となって操縦安定性が不充分となり、逆に20mmを超えとビード部4が不必要に大型化して無駄な重量増加を招く。なおこの距離Wと、前記内側ゴム20の厚さTiとの比Ti/Wを0.5〜0.8の範囲とするのが、ビード剛性とスリム化とのバランスの観点から好ましい。   In the tire 1 of the present embodiment, the distance W from the point Pj on the ply main body 6a that is 5 mm away from the outer surface SU of the bead core 5 to the outer piece 15o is in the range of 14 to 20 mm. If the distance W is less than 14 mm, the bead rigidity is too small and the steering stability is insufficient. Conversely, if the distance W is more than 20 mm, the bead portion 4 is unnecessarily increased in size and causes an unnecessary weight increase. The ratio Ti / W between the distance W and the thickness Ti of the inner rubber 20 is preferably in the range of 0.5 to 0.8 from the viewpoint of the balance between bead rigidity and slimming.

以上、本発明の特に好ましい実施形態について詳述したが、本発明は図示の実施形態に限定されることなく、種々の態様に変形して実施しうる。   As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

図1の構造をなしかつ表1の仕様を有する重荷重用タイヤ(11R22.5)を試作するとともに、各試供タイヤのビード耐久性をテストし評価した。なおビードワインド構造では、副部11の角度θは15°、距離Laは4.0mm、距離Lbは2.0mm、充填ゴム13の複素弾性率E* 3は6.0MPaで全て同仕様としている。又従来例は、図4に示す如く、カーカスのプライ折返し部をビードエーペックスゴムの外側面に沿ってU字に巻き上げた非ビードワインド構造とし、ビードエーペックスゴムのビードベースラインBLからの高さh2を65mm、プライ折返し部の高さを35mmとしている。   A heavy-duty tire (11R22.5) having the structure shown in FIG. 1 and having the specifications shown in Table 1 was prototyped, and the bead durability of each sample tire was tested and evaluated. In the bead wind structure, the angle θ of the sub-portion 11 is 15 °, the distance La is 4.0 mm, the distance Lb is 2.0 mm, and the complex elastic modulus E * 3 of the filled rubber 13 is 6.0 MPa. . As shown in FIG. 4, the conventional example has a non-bead wind structure in which the ply turn-up portion of the carcass is rolled up along the outer surface of the bead apex rubber, and the height h2 of the bead apex rubber from the bead base line BL. Is 65 mm, and the height of the ply turn-up portion is 35 mm.


又各試供タイヤを形成する際のビードエーペックスゴムのゴム重量を、従来例を100とした指数で比較した。値が小なほど軽量である。
,
Further, the rubber weight of the bead apex rubber when forming each sample tire was compared with an index based on the conventional example as 100. The smaller the value, the lighter.

(1)ビード耐久性;
ドラム試験機を用い、タイヤをリム(7.50×22.5)、内圧(700kPa)、縦荷重(26.72kN×3)の条件下にて、速度30km/hで走行させ、ビード部に損傷が発生するまでの走行時間を、従来例を100とした指数で示した。値が大なほど耐久性に優れている。
(1) Bead durability;
Using a drum tester, the tire was run at a speed of 30 km / h under the conditions of a rim (7.50 × 22.5), internal pressure (700 kPa), and longitudinal load (26.72 kN × 3). The running time until damage occurred is shown as an index with the conventional example being 100. The greater the value, the better the durability.

Figure 2007153318
Figure 2007153318

表の如く、実施例のタイヤは、ビード部をスリム化して軽量化を図りながら、ビード耐久性を高く確保しうるのが確認できる。   As shown in the table, it can be confirmed that the tires of the examples can ensure high bead durability while reducing the weight of the bead portion and reducing the weight.

本発明の重荷重用タイヤの一実施例を示す断面図である。It is sectional drawing which shows one Example of the tire for heavy loads of this invention. ・ビード部のビードワインド構造を説明する拡大断面図である。-It is an expanded sectional view explaining the bead wind structure of a bead part. ビード部をビード補強層とともに説明する拡大断面図である。It is an expanded sectional view explaining a bead part with a bead reinforcement layer. 表1の従来例のビード構造を示す断面図である。It is sectional drawing which shows the bead structure of the prior art example of Table 1. ビードワインド構造の従来技術を説明する断面図である。It is sectional drawing explaining the prior art of a bead wind structure.

符号の説明Explanation of symbols

2 トレッド部
3 サイドウォール部
4 ビード部
5 ビードコア
6 カーカス
6A カーカスプライ
6a プライ本体部
6b プライ折返し部
8 ビードエーペックスゴム
9 クリンチゴム
10 主部
11 副部
15 ビード補強層
15A 曲線状部
15o 外片
15i 内片
20 内側ゴム
21 低弾性ゴム部
30 外側ゴム
31 低弾性ゴム部
X1 第1の基準線
X2 第2の基準線
2 Tread portion 3 Side wall portion 4 Bead portion 5 Bead core 6 Carcass 6A Carcass ply 6a Ply main body portion 6b Ply folded portion 8 Bead apex rubber 9 Clinch rubber 10 Main portion 11 Sub portion 15 Bead reinforcement layer 15A Curved portion 15o Inside outer piece 15i Piece 20 Inner rubber 21 Low elastic rubber part 30 Outer rubber 31 Low elastic rubber part X1 First reference line X2 Second reference line

Claims (5)

トレッド部からサイドウォール部をへてビード部のビードコアに至るプライ本体部と、該プライ本体部に連なりかつ前記ビードコアの廻りをタイヤ軸方向内側から外側に折り返されたプライ折返し部とを有する1枚のカーカスプライからなるカーカスを具えた重荷重用タイヤであって、
前記プライ折返し部は、ビードコアのタイヤ軸方向内側の内の側面とタイヤ半径方向内側の内面とタイヤ軸方向外側の外の側面とに沿って湾曲する主部、及び該主部に連なり前記ビードコアのタイヤ半径方向外側の外面の近傍を前記プライ本体部に向かって傾斜してのびる副部からなり、
かつ前記ビード部に、前記プライ折返し部の主部に沿いその半径方向内方を通る曲線状部と、この曲線状部のタイヤ軸方向外側で前記主部と離れて半径方向外方に向かってタイヤ軸方向外側に傾斜する外片と、前記曲線状部のタイヤ軸方向内側で前記プライ本体部のタイヤ軸方向内側面に沿ってのびる内片とからなるビード補強層を設け、
しかも前記外片の半径方向外端から、ビードベースラインまでの半径方向高さを25〜40mm、かつ前記ビードコアの外面から5mmの距離を隔たるプライ本体部上の点Pjから、前記外片までの距離を14〜20mmとするとともに、
前記外片の半径方向外端において、前記プライ本体部と外片との間に介在する内側ゴムは、複素弾性率E* 1が3.0〜6.0MPaの低弾性ゴムからなりかつ前記外片に隣接する低弾性ゴム部を含み、しかも前記外片の半径方向外端を通りプライ本体部に直交する第1の基準線における前記内側ゴムの厚さTiを7.0〜13.0mm、かつ該第1の基準線における前記低弾性ゴム部の厚さtiとの比ti/Tiを0.9以上とする一方、
前記外片の半径方向外端において、前記外片とタイヤ外側面と間に介在する外側ゴムは、複素弾性率E*2が3.0〜6.0MPaの低弾性ゴムからなりかつ前記外片に隣接する低弾性ゴム部を含み、しかも前記外片の半径方向外端を通りタイヤ外側面に直交する第2の基準線における前記外側ゴムの厚さToを5.0〜11.0mm、かつ該第2の基準線における前記低弾性ゴム部の厚さtoとの比to/Toを0.4以上としたことを特徴とする重荷重用タイヤ。
One sheet having a ply body part extending from the tread part through the sidewall part to the bead core of the bead part, and a ply folded part connected to the ply body part and folded around the bead core from the inner side to the outer side in the tire axial direction. A heavy duty tire having a carcass made of a carcass ply of
The ply folded portion includes a main portion that curves along an inner side surface of the bead core in the tire axial direction inner side, an inner surface in the tire radial direction inner side, and an outer side surface in the tire axial direction outer side, and the main portion that is connected to the main portion. Consists of a sub-portion extending near the outer surface of the outer side in the tire radial direction toward the ply body,
And a curved portion passing through the inner portion in the radial direction along the main portion of the ply turn-up portion in the bead portion, and away from the main portion on the outer side in the tire axial direction of the curved portion toward the outer side in the radial direction. A bead reinforcement layer is provided that includes an outer piece that is inclined outward in the tire axial direction, and an inner piece that extends along the tire axial direction inner side surface of the ply main body portion on the inner side in the tire axial direction of the curved portion,
In addition, the height in the radial direction from the radially outer end of the outer piece to the bead base line is 25 to 40 mm, and the point Pj on the ply main body that is 5 mm away from the outer surface of the bead core to the outer piece. And the distance of 14-20 mm,
An inner rubber interposed between the ply main body portion and the outer piece at a radially outer end of the outer piece is made of a low elastic rubber having a complex elastic modulus E * 1 of 3.0 to 6.0 MPa and the outer rubber. A thickness of the inner rubber at a first reference line including a low elastic rubber portion adjacent to the piece and passing through the radially outer end of the outer piece and perpendicular to the ply main body portion is 7.0 to 13.0 mm; And the ratio ti / Ti with respect to the thickness ti of the low elastic rubber part at the first reference line is 0.9 or more,
The outer rubber interposed between the outer piece and the outer surface of the tire at the radially outer end of the outer piece is made of a low elastic rubber having a complex elastic modulus E * 2 of 3.0 to 6.0 MPa, and the outer piece. And a thickness To of the outer rubber at a second reference line that passes through the radially outer end of the outer piece and is orthogonal to the outer surface of the tire, and 5.0 to 11.0 mm, and A heavy duty tire characterized in that a ratio to / To with respect to the thickness to of the low elastic rubber portion at the second reference line is set to 0.4 or more.
前記内側ゴムは、前記プライ本体部と前記外片との間を通って前記副部から半径方向外側にのびる断面三角形状のビードエーペックスゴムからなり、かつ前記外側ゴムは、少なくともビードベースラインから前記外片のタイヤ軸方向外側を通って半径方向外側にのびるリムずれ防止用のクリンチゴムからなることを特徴とする請求項1記載の重荷重用タイヤ。   The inner rubber is made of a bead apex rubber having a triangular cross section extending between the ply main body part and the outer piece and extending radially outward from the sub part, and the outer rubber is at least from the bead base line. 2. The heavy duty tire according to claim 1, wherein the tire is made of clinch rubber for preventing rim deviation extending outward in the tire axial direction and extending radially outward. 前記内側ゴムの低弾性ゴム部の複素弾性率E* 1と、前記外側ゴムの低弾性ゴム部の複素弾性率E* 2との差|E* 1−E* 2|は、3.0MPa以下であることを特徴とする請求項1又は2記載の重荷重用タイヤ。   The difference | E * 1-E * 2 | between the complex elastic modulus E * 1 of the low elastic rubber portion of the inner rubber and the complex elastic modulus E * 2 of the low elastic rubber portion of the outer rubber is 3.0 MPa or less. The heavy duty tire according to claim 1, wherein the tire is for heavy loads. 前記ビードエーペックスゴムは、前記低弾性ゴム部のみからなることを特徴とする請求項2記載の重荷重用タイヤ。   The heavy load tire according to claim 2, wherein the bead apex rubber includes only the low elastic rubber portion. 前記内側ゴムの厚さTiと外側ゴムの厚さToとの比To/Tiは0.6〜0.9であることを特徴とする請求項1〜4の何れかに記載の重荷重用タイヤ。   5. The heavy duty tire according to claim 1, wherein a ratio To / Ti of a thickness Ti of the inner rubber and a thickness To of the outer rubber is 0.6 to 0.9.
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JP2009018717A (en) * 2007-07-12 2009-01-29 Sumitomo Rubber Ind Ltd Tire for heavy load
JP7547760B2 (en) 2020-04-02 2024-09-10 住友ゴム工業株式会社 Pneumatic tires

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