JP4571270B2 - Pneumatic run-flat tire and manufacturing method - Google Patents
Pneumatic run-flat tire and manufacturing method Download PDFInfo
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- JP4571270B2 JP4571270B2 JP2000133423A JP2000133423A JP4571270B2 JP 4571270 B2 JP4571270 B2 JP 4571270B2 JP 2000133423 A JP2000133423 A JP 2000133423A JP 2000133423 A JP2000133423 A JP 2000133423A JP 4571270 B2 JP4571270 B2 JP 4571270B2
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- 238000004519 manufacturing process Methods 0.000 title claims description 9
- 229920001971 elastomer Polymers 0.000 claims description 91
- 239000005060 rubber Substances 0.000 claims description 91
- 230000003014 reinforcing effect Effects 0.000 claims description 36
- 239000000463 material Substances 0.000 claims description 24
- 239000011324 bead Substances 0.000 claims description 16
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- 239000000945 filler Substances 0.000 claims description 4
- 238000003490 calendering Methods 0.000 claims description 3
- 238000005096 rolling process Methods 0.000 claims description 3
- 239000002131 composite material Substances 0.000 claims description 2
- 230000010354 integration Effects 0.000 claims 1
- 238000004804 winding Methods 0.000 claims 1
- 238000012360 testing method Methods 0.000 description 8
- 230000000694 effects Effects 0.000 description 5
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- 239000000446 fuel Substances 0.000 description 2
- 229920001875 Ebonite Polymers 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
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- 239000006261 foam material Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
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- 230000002040 relaxant effect Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
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- Moulding By Coating Moulds (AREA)
- Tyre Moulding (AREA)
- Tires In General (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、空気入りタイヤがパンクして内圧が低下した時、その状態のままで補修可能な安全な場所まで、相当の距離を走行し得るようにサイド部を補強した空気入りランフラットタイヤに係り、特には、高性能のランフラット走行を有しながら、通常走行時においては快適な乗り心地や道路騒音の低いランフラット走行可能なラジアルタイヤ及びその製造方法に関する。
【０００２】
【従来の技術】
空気入りタイヤでランフラット走行が可能、即ち、パンクしてタイヤ内圧が大気圧に等しくなるまで低下しても、ある程度の距離を安心して走行が可能なタイヤ（以後、ランフラットタイヤと呼ぶ。）としては、タイヤの空気室内におけるリムの部分に、金属、合成樹脂製の環状の中子を取り付けた中子タイプや、軽量な発泡材料を内部に充填した充填タイプ、或はタイヤのサイドウォール内面のビード部からショルダー区域にかけて、カーカスの内面に断面が三日月状の比較的硬質なゴムの層を配置してサイド内壁を補強したサイド補強タイプ等がよく知られている。
【０００３】
これらのタイプのうち、中子タイプは、ランフラット走行に当たって荷重支持能力が高いことから、バネ下重量をあまり問題にしない４輪以上の貨物運搬用の車両や軍用車両向けとして、またサイド補強タイプは、比較的荷重付加が小さく、リム組みが簡易で乗り心地や燃費等に影響の大きいばね下重量の低減を重視する乗用車向け及び２輪車向けとして用いられている。サイド補強タイプのランフラットタイヤを乗用車向けに実際に適用した際に、一番問題として指摘されるのは、ゴツゴツとした不快な乗り心地と騒がしい道路騒音であり、その対策が望まれている。
【０００４】
【発明が解決しようとする課題】
しかしながら、このサイド補強タイプのランフラットタイヤは、タイヤのサイド部の剛性を高めることによって、ランフラット性能が付与されているのであるから、当然のことながら振動吸収性能と騒音減衰性能に乏しく、特に乗用車及びライトバンに装着されるランフラットタイヤとしては、通常走行時の乗り心地と道路騒音面で苦情と不評が多かった。
【０００５】
本発明は、上記事実を考慮し、ランフラット走行時の耐久性と信頼性を充分に確保しながら、なおかつ、通常走行時には満足のいく乗り心地と道路騒音の低い主として乗用車用のランフラットタイヤを提供すること、及びかかる構造のランフラットタイヤを従来の工程と設備の下で簡便に製造する方法を提案することを課題とする。
【０００６】
【課題を解決するための手段】
本発明は、上記課題を解決すべく成されたもので、タイヤのサイド部の剛性補強構造と振動減衰機構の高度な両立を図るべく鋭意探究した結果、本発明を完成するに至った。
【０００７】
即ち本発明の空気入りランフラットタイヤは、一対のビードコア間にわたってトロイド状に連なり、両端部が前記ビードコアをタイヤ内側から外側へ巻き上げられる少なくとも１枚のラジアルカーカスプライからなるカーカスと、前記カーカスのサイド領域のタイヤ軸方向外側に配置されてタイヤサイド部を構成するサイドゴム層と、前記カーカスのクラウン領域のタイヤ径方向外側に配置されてトレッド部を構成するトレッドゴム層と、前記トレッドゴム層とカーカスのクラウン領域の間に配置される少なくとも１枚のベルトプライからなるベルトと、前記カーカスのタイヤ内方全面に配置されるインナーライナーと、前記一方のビードコアから他方のビードコアへ延びるカーカス本体部分と前記ビードコアに巻き上げられる巻上部分との間に配置されるビードフィラー層と、を備えた空気入りランフラットタイヤであって、前記カーカスのタイヤサイド部からショルダー領域の内側にかけて、タイヤ回転軸に沿った断面形状が略三日月形である、少なくとも１層の補強ゴム層を有するサイド補強層を有し、前記カーカスのタイヤサイド部からショルダー領域の内側にかけて、前記タイヤカーカスと前記サイド補強層との間に振動抑制ゴム層を配設し、前記振動抑制ゴム層のタイヤ回転軸に沿った断面の厚みが、タイヤ径方向の上端部と下端部を除いて一定であることを特徴としている。
【０００８】
本発明の、カーカスサイド部からショルダー領域の内方にかけて配設され、タイヤ回転軸に沿った断面形状が略三日月形である補強ゴム層としては、タイヤにランフラット性能を付与できるに足る諸種の高剛性ゴム特に軽比重の高剛性ゴム組成物を適宜選択使用することが可能である。これら高剛性ゴムの例としては、補強性のカーボンブラックや他有機／無機の補強剤を比較的多量に充填した高剛性ゴム配合物、又は有機／無機の短繊維及びこれらの断面中空ないしは断面異形の繊維を充填した高剛性ゴム組成物等が好適に用いられる。
【０００９】
なお、上述の断面形状が略三日月形である補強ゴム層の材質の硬度（Ｈｄ）は、７５以上であることが望ましい。硬度が７５に満たない補強ゴム層では、サイド内壁の剛性が不足して、パンク時において車体重量を支えきれず、充分な距離をランフラット走行することが出来ない。もしくは、サイド剛性を確保するためには補強ゴム層の断面肉厚を上げざるを得ず、タイヤの重量を益々重くするだけにとどまらず、サイド部の屈曲疲労性を悪化させ、通常走行時においても疲労寿命を悪くする。
【００１０】
本発明のランフラットタイヤにおいては、カーカスのタイヤサイド部からショルダー領域の内側にかけて、前記タイヤカーカスと前記サイド補強層との間に、特殊な振動抑制ゴム層が配設されていることが大きな特徴である。この特殊な振動抑制ゴム層が、タイヤカーカスとサイド補強層との間に存在することにより、タイヤ踏面より入力される振動や騒音が緩和され減衰されることにより、ランフラットタイヤでありながら良好な乗り心地と道路騒音の防止が得られる。
【００１１】
なお、この振動抑制ゴム層が、前記カーカスのタイヤサイド部からショルダー領域の内側にかけて、タイヤカーカスとサイド補強層との間の境界面の少なくとも全域に亙って実質的に配設されている方が、上述の乗り心地の改善と道路騒音の低減により効果的である。
【００１２】
本発明の振動抑制ゴム層のタイヤ回転軸に沿った断面の厚みは、そのタイヤ径方向の上端部と下端部の近傍を除いて、ほぼ一定であることが望ましい。不均一な断面厚みは、タイヤ走行時のサイド部の屈曲疲労寿命に悪い影響を与える。また後述するように、本発明の振動抑制ゴム層をカーカスプライの圧延工程で同時にカレンダー加工する際にも、この振動抑制ゴム層の断面厚みが、ほぼ一定であることが作業を容易にし望ましい。
【００１３】
特に乗用車用のランフラットタイヤを考えた場合は、上述の振動抑制ゴム層の断面厚みは、０．４〜２．０ｍｍでほぼ一定であることが好ましい。０．４ｍｍに満たない厚みの場合は、乗用車としての乗り心地の改善と道路騒音の低減の効果を発揮するには不充分であり、２．０ｍｍを越える厚みにすることは不要でありタイヤ重量をいたずらに増し燃費を悪くすることになる。
【００１４】
本発明の振動抑制ゴム層に使用される材質の硬度（Ｈｄ）は、高硬度のサイド補強層に起因するゴツゴツした硬さと騒音を緩和し緩衝するために、サイド補強層のゴム材質硬度よりも低いことが要請される。振動抑制ゴム層の材質硬度（Ｈｄ）が、サイド補強層のゴム硬度より硬ければ緩衝し緩和する効果は少なくなる。同様に、振動抑制ゴム層の材質の損失正接（ｔａｎδ）も、高硬度のサイド補強層の硬さと騒音を緩衝し緩和するために、サイド補強層の材質の損失正接よりも大きいことが望ましい。
【００１５】
本発明の振動抑制ゴム層の材質の硬度（Ｈｄ）と前記カーカスの最内層プライの被覆ゴムの材質硬度との高低関係には、２つのケースがあり、それぞれの長所と短所を勘案して適宜選択される。振動抑制ゴム層の材質硬度がカーカス最内層プライの被覆ゴムの材質硬度よりも低い場合は、両側のサイド補強層と最内層プライ層よりも真中の振動抑制ゴム層が最も軟らかい構成となり、サイド補強層から最内層プライ層への振動と騒音の伝達係数が最も小さくなり、ランフラットタイヤの騒音と乗り心地の改善には好適だが、軟らかい振動抑制ゴム層の両界面での歪が大となるので、耐久性が若干低下する懸念がある。一方、振動抑制ゴム層の材質硬度がカーカス最内層プライの被覆ゴムの材質硬度より高い場合は、サイド補強層から振動抑制ゴム層及び最内層プライ層と順次硬度が変化しているので歪勾配が滑らかになりサイド部の屈曲耐久性には優れるが、その分ランフラットタイヤの騒音乗り心地改善には、上記ケースに比べて見劣りすることになる。総合的に勘案して、振動抑制ゴム層の材質硬度は、断面三日月形のサイド補強ゴムよりも低く、カーカス最内層プライの被覆ゴムの硬度より高い後者のケースの方が、非常時及び通常走行時の耐久性と信頼性により優れるので、好まれる場合が多い。
【００１６】
最後に、本発明のタイヤを製造する方法につき説明する。一般にタイヤの製造は、個々の部材を圧延(カレンダー)工程や押出し工程で長尺シート物として製造し、個々のタイヤに応じたサイズ長さに裁断し、成形ドラム上で貼り付けて加硫前グリーンタイヤを形成するのであるが、本発明タイヤも従来のこういう方法で製造できる。しかしながら、より効率的なタイヤ製造方法として、我々は、前記カーカスの最内層プライのコードに被覆ゴムを圧延するカレンダー工程において、該カーカスプライの片面に前記振動抑制ゴム層の未加硫シートを同時に圧延して、予めカーカスプライと振動抑制ゴム層を一体化した後、該複合シートをタイヤの成形工程へ供することを特徴とする空気入りランフラットタイヤの製造方法を提案する。本方法により、タイヤの成形用部材として、本発明では振動抑制ゴム層のシートが１枚増えているのであるが、本発明の上述の方法によれば、従来とほぼ同じ設備と工数で本発明の空気入りランフラットタイヤを製造できる利点がある。
【００１７】
なお、空気入りタイヤは、夫々のサイズに応じて、ＪＡＴＭＡ（日本）、ＴＲＡ（米国）及びＥＴＲＴＯ（欧州）等が発行する規格に定められた標準リムに装着されて使用され、この標準リムが通常正規リムと称される。
【００１８】
本明細書でもこの慣用呼称に従い、「正規リム」とは米国のタイヤとリムの協会ＴＲＡが発行する２０００年版のＹＥＡＲ ＢＯＯＫに定められた適用サイズにおける標準リムを指す。同様に、「正規荷重」及び「正規内圧」とは、米国のタイヤとリムの協会ＴＲＡが発行する２０００年版のＹＥＡＲ ＢＯＯＫに定められた適用サイズ・プライレーティングにおける最大荷重及び最大荷重に対応する空気圧を指す。 ここで、荷重とは下記規格に記載されている適用サイズにおける単輪の最大荷重（最大負荷能力）のことであり、内圧とは下記規格に記載されている適用サイズにおける単輪の最大荷重（最大負荷能力）に対応する空気圧のことであり、リムとは下記規格に記載されている適用サイズにおける標準リム（または“Approved Rim”、“Recommended Rim” ）のことである。
【００１９】
【発明の実施の形態】
本発明の実施の形態を図面にしたがって説明する。
【００２０】
図１と図２には、本発明の実施の形態に係わるランフラットタイヤが、左半分の断面図にて示されている。本実施形態のランフラットタイヤは乗用車用であり、サイズ２２５／６０Ｒ１６（ラジアル構造タイヤ）の空気入りランフラットタイヤで、図１（タイプＡとする）は、振動抑制ゴムがカーカス内面とサイド補強ゴム層との間にあって、サイド補強ゴム層とカーカス層との境界面を越えて径方向外側と径方向内側にまで延び、振動抑制ゴム層がサイド補強ゴム層を完全に包み込む断面形態で存在する。図２（タイプＢとする）では、振動抑制ゴムがカーカス内面とサイド補強ゴム層との間にあって、サイド補強ゴム層とカーカス層との境界面のタイヤ径方向中央部を中心に部分的に介在して存在する断面形態を成している。図１（タイプＡ）のタイヤ断面では、サイド補強ゴム層とカーカス層との間に振動抑制ゴムが必ず介在するが、図２（タイプＢ）のタイヤ断面では、サイド補強ゴム層とカーカス層との間の中央部分にだけ振動抑制ゴムが介在するだけである。
【００２１】
本発明の実施形態を示すために、タイヤカーカス最内層プライの内面のサイド部からショルダー領域にかけて、表１に示す振動抑制ゴム層の配置構造と材質特性のランフラットタイヤを試作した。実施例▲１▼〜▲４▼タイヤは、振動抑制ゴム層を有するが、実施タイヤ▲２▼〜▲４▼は振動抑制ゴム層がサイド補強層を包み込むタイプＡ（図１）の構造をなし、実施タイヤ▲１▼は振動抑制ゴム層がカーカス層とサイド補強ゴム層の境界中央部に部分的に介在するタイプＢ（図２）の構造である。夫々のタイヤの振動抑制ゴムの硬度は、実施タイヤ▲１▼と▲４▼は５５であり、実施タイヤ▲２▼と▲３▼は夫々８０と３０である。なお、実施タイヤに用いられた断面三日月状のサイド補強ゴム層は、特開平１１−２４５６３６に開示されている配合で作成され、その硬度は９０であった。全ての試作タイヤの最内側のカーカスの被覆ゴムの硬度は４０である。
【００２２】
【表１】
本発明の効果を確認するために、上記の仕様で試作した各タイヤにつき、ランフラット走行寿命と乗り心地試験及び道路騒音の測定を行ない、その結果を、従来タイヤの性能を１００として相対的に指数化して表２に示した。ここで、相対評価指数は数字が大きい程優れており、小さいほど劣っていることを意味する。
【００２４】
【表２】
本発明タイヤのランフラット走行性能は、従来タイヤの性能とほぼ同等乃至は同等以上である。本発明の振動抑制ゴム層が介在するタイヤは、道路騒音レベルと乗り心地が改善されていること、特に実施タイヤ▲２▼〜▲４▼に見られるように、Ａタイプの振動抑制ゴムがサイド補強ゴム層とカーカス層との境界面を完全に覆っている場合はその効果が著しいことが判る。更に、振動抑制ゴム層の硬度が、本発明の好ましい範囲３５〜７５の内にある実施例▲４▼のタイヤにおいては、道路騒音と乗り心地の改善効果が最大であることが実証された。
【００２６】
なお、本実施形態でのタイヤ性能の試験方法は次の通りである。
【００２７】
＜ランフラット走行寿命＞
試験タイヤを正規リムに組み内圧をゼロとして、正規荷重３７５Ｋｇｆをかけて直径１７００ｍｍのドラム試験機に押し付け、時速８０ｋｍ／ｈで故障が発生するまで走行させ、その走行距離の長さでランフラット走行の寿命を評価した。
【００２８】
＜道路騒音（ロードノイズ）試験＞
サイズ１７５／７０Ｒ１４の供試タイヤを正規リムに組み排気量２０００ｃｃのセダン型乗用車に４輪とも装着して、２名が乗車してロードノイズ評価用テストコースを時速６０ｋｍの速度で走行して、運転席の背もたれ背面部の中央に集御マイクを取り付け、周波数１００〜５００Ｈｚ及び３００〜５００Ｈｚの全音圧（デシベル）を測定した。この測定値を従来タイヤを１００として指数表示し、指数が高いほどロードノイズは良好と評価する。
【００２９】
＜乗り心地評価＞
幅２ｃｍで高さ１ｃｍの突起物が取り付けられた外径２ｍのタイヤ試験用鉄製ドラムの上に、正規荷重を負荷させて供試タイヤを押し付けてドラムを回転させ、タイヤがドラム上の突起を乗り越したときの上下負荷方向の振動波形を加速度計にて測定し、その第１周期の振幅の逆数を求め、従来タイヤを１００として指数で表示する。なお、この指数が大きい程乗り心地は良好である。
【００３０】
【発明の効果】
以上説明したように、本発明の空気入りランフラットタイヤは、振動抑制ゴム層をサイド補強層とカーカス内面との間に介在させてなるので、通常走行時においては乗り心地が良く道路騒音を抑制する快適な乗用車用タイヤの性能を保持し、パンクで内圧が低下した時には、安全で信頼性のおけるランフラット走行が可能な優れたタイヤである。
【図面の簡単な説明】
【図１】本発明の１つの実施形態(タイプＡ)に係る空気入りランフラットタイヤの半断面図である。
【図２】本発明の他の実施形態(タイプＢ)に係る空気入りランフラットタイヤの半断面図である。
【符号の説明】
１Ａ ビードコア
２Ａ ビードフィラー
３Ａ カーカス
４Ａ インナーライナー
５Ａ サイドゴム部
６Ａ ベルト層
７Ａ トレッドゴム部
１Ｂ ビードコア
２Ｂ ビードフィラー
３Ｂ カーカス
４Ｂ インナーライナー
５Ｂ サイドゴム部
６Ｂ ベルト層
７Ｂ トレッドゴム部[0001]
BACKGROUND OF THE INVENTION
The present invention provides a pneumatic run-flat tire whose side portions are reinforced so that it can travel a considerable distance to a safe place that can be repaired when the pneumatic tire punctures and the internal pressure decreases. In particular, the present invention relates to a radial tire that has a high-performance run-flat running and can be run-flat with a low level of road comfort and a comfortable ride during normal running, and a method for manufacturing the same.
[0002]
[Prior art]
It is possible to run flat with a pneumatic tire, that is, a tire that can travel with a certain distance even if it is punctured and the tire internal pressure becomes equal to the atmospheric pressure (hereinafter referred to as a run flat tire). For example, a core type in which a ring core made of metal or synthetic resin is attached to the rim portion in the air chamber of the tire, a filling type in which a lightweight foam material is filled, or the inner surface of the sidewall of the tire A side-reinforcing type in which a relatively hard rubber layer having a crescent cross section is disposed on the inner surface of the carcass from the bead portion to the shoulder region, and the side inner wall is reinforced is well known.
[0003]
Of these types, the core type has a high load-bearing capacity when running on a run-flat, so it is suitable for four-wheel or more freight vehicles and military vehicles that do not have much unsprung weight, and side reinforcement type. Is used for passenger cars and two-wheeled vehicles that place emphasis on the reduction of unsprung weight, which has a relatively small load addition, a simple rim assembly, and a large influence on ride comfort and fuel consumption. When side-reinforced run-flat tires are actually applied to passenger cars, the biggest problems are pointed out to the harsh and uncomfortable riding comfort and noisy road noise, and countermeasures are desired.
[0004]
[Problems to be solved by the invention]
However, this side reinforcement type run flat tire has run flat performance by increasing the rigidity of the side portion of the tire, so it naturally has poor vibration absorption performance and noise attenuation performance, especially As run-flat tires installed in passenger cars and light vans, there were many complaints and disapprovals regarding the riding comfort and road noise during normal driving.
[0005]
In consideration of the above-mentioned facts, the present invention provides a run-flat tire mainly for passenger cars, which has sufficient durability and reliability during run-flat driving, yet has satisfactory ride comfort and low road noise during normal driving. It is an object of the present invention to provide a method for easily manufacturing a run-flat tire having such a structure under conventional processes and equipment.
[0006]
[Means for Solving the Problems]
The present invention has been made to solve the above-mentioned problems, and as a result of earnestly searching for a high degree of compatibility between the rigidity reinforcing structure of the tire side portion and the vibration damping mechanism, the present invention has been completed.
[0007]
That is, the pneumatic run-flat tire of the present invention includes a carcass composed of at least one radial carcass ply that is connected in a toroidal shape between a pair of bead cores, and whose both ends are wound up from the inside of the tire to the outside, and the side of the carcass A side rubber layer constituting a tire side portion disposed outside the tire axial direction of the region, a tread rubber layer disposed outside the tire radial direction of the crown region of the carcass and constituting a tread portion, the tread rubber layer and the carcass A belt composed of at least one belt ply disposed between the crown regions of the carcass, an inner liner disposed on the entire inner surface of the tire of the carcass, a carcass body portion extending from the one bead core to the other bead core, and the With the hoisting part wound up on the bead core A bead filler layer disposed on the tire, and a cross-sectional shape along the tire rotation axis from the tire side portion of the carcass to the inside of the shoulder region is a substantially crescent shape, having a side reinforcing layer having a reinforcing rubber layer of the first layer, over the inner shoulder region from the tire side portion of the carcass, and arranging the vibration suppressing rubber layer between the side reinforcing layer and the tire carcass, wherein The vibration suppression rubber layer is characterized in that the cross-sectional thickness along the tire rotation axis is constant except for the upper end portion and the lower end portion in the tire radial direction .
[0008]
The reinforcing rubber layer of the present invention, which is disposed from the carcass side portion to the inside of the shoulder region and has a substantially crescent-shaped cross section along the tire rotation axis, has various types sufficient to provide run-flat performance to the tire. It is possible to appropriately select and use a high-rigid rubber, particularly a light-specific gravity high-rigid rubber composition. Examples of these high-rigidity rubbers include high-rigidity rubber compounds filled with a relatively large amount of reinforcing carbon black and other organic / inorganic reinforcing agents, or organic / inorganic short fibers and their hollow cross-sections or irregular shapes. A high-rigidity rubber composition filled with the above fibers is preferably used.
[0009]
Note that the hardness (Hd) of the material of the reinforcing rubber layer whose cross-sectional shape is approximately crescent is preferably 75 or more. In the reinforcing rubber layer having a hardness of less than 75, the rigidity of the side inner wall is insufficient, and the weight of the vehicle body cannot be supported at the time of puncture, and a sufficient distance cannot be run-run. Or, in order to ensure the side rigidity, it is necessary to increase the cross-sectional thickness of the reinforcing rubber layer, not only increasing the weight of the tire, but also worsening the bending fatigue of the side part, during normal driving Even worse the fatigue life.
[0010]
The run flat tire of the present invention is characterized in that a special vibration suppressing rubber layer is disposed between the tire carcass and the side reinforcing layer from the tire side portion of the carcass to the inside of the shoulder region. It is. This special vibration suppression rubber layer is present between the tire carcass and the side reinforcing layer, so that vibrations and noises input from the tire tread are reduced and attenuated. Riding comfort and prevention of road noise can be obtained.
[0011]
The vibration suppression rubber layer is disposed substantially over at least the entire boundary surface between the tire carcass and the side reinforcing layer from the tire side portion of the carcass to the inside of the shoulder region. However, it is effective by improving the above-mentioned riding comfort and reducing road noise.
[0012]
It is desirable that the thickness of the cross section along the tire rotation axis of the vibration suppressing rubber layer of the present invention is substantially constant except for the vicinity of the upper end portion and the lower end portion in the tire radial direction. The non-uniform cross-sectional thickness adversely affects the bending fatigue life of the side portion when the tire is running. As will be described later, when the vibration suppressing rubber layer of the present invention is calendered at the same time in the carcass ply rolling process, it is desirable that the cross-sectional thickness of the vibration suppressing rubber layer is substantially constant to facilitate work.
[0013]
In particular, when a run-flat tire for a passenger car is considered, it is preferable that the cross-sectional thickness of the vibration suppressing rubber layer is approximately constant at 0.4 to 2.0 mm. If the thickness is less than 0.4 mm, it is not sufficient to improve the riding comfort and reduce the road noise as a passenger car, and it is not necessary to have a thickness exceeding 2.0 mm. This will unnecessarily increase the fuel efficiency.
[0014]
The hardness (Hd) of the material used for the vibration suppressing rubber layer of the present invention is more than the hardness of the rubber material of the side reinforcing layer in order to mitigate and buffer the rugged hardness and noise caused by the high hardness side reinforcing layer. Low is required. If the material hardness (Hd) of the vibration suppressing rubber layer is higher than the rubber hardness of the side reinforcing layer, the effect of buffering and relaxing is reduced. Similarly, the loss tangent (tan δ) of the material of the vibration suppressing rubber layer is desirably larger than the loss tangent of the material of the side reinforcing layer in order to buffer and mitigate the hardness and noise of the high-hardness side reinforcing layer.
[0015]
There are two cases in the height relationship between the hardness (Hd) of the material of the vibration suppressing rubber layer of the present invention and the material hardness of the covering rubber of the innermost layer ply of the carcass, and it is appropriately determined in consideration of the respective advantages and disadvantages. Selected. When the material hardness of the vibration suppression rubber layer is lower than the material hardness of the covering rubber of the carcass innermost layer ply, the vibration suppression rubber layer in the middle of the side reinforcement layers on both sides and the innermost ply layer is the softest structure, and side reinforcement The vibration and noise transfer coefficient from the inner layer to the innermost ply layer is the smallest, which is suitable for improving the noise and ride comfort of run-flat tires, but because the distortion at both interfaces of the soft vibration suppression rubber layer is large There is a concern that the durability may be slightly lowered. On the other hand, when the material hardness of the vibration suppressing rubber layer is higher than the material hardness of the covering rubber of the carcass innermost layer ply, the strain gradient is changed because the hardness sequentially changes from the side reinforcing layer to the vibration suppressing rubber layer and the innermost ply layer. Although it is smooth and has excellent bending durability at the side portion, it is inferior to the above case in improving the noise riding comfort of the run-flat tire. Considering comprehensively, the material hardness of the vibration suppression rubber layer is lower than that of the side reinforcing rubber with a crescent cross section, and the latter case is higher in the case of emergency and normal running than the hardness of the covering rubber of the carcass innermost layer ply. It is often preferred because it is more durable and reliable.
[0016]
Finally, a method for producing the tire of the present invention will be described. In general, tires are manufactured by manufacturing individual members as long sheets in a rolling (calendar) process or extrusion process, cutting them into sizes according to the individual tires, and pasting them on a forming drum before vulcanization. A green tire is formed, and the tire of the present invention can also be manufactured by such a conventional method. However, as a more efficient tire manufacturing method, in the calendering process in which the coated rubber is rolled on the cord of the innermost ply of the carcass, the uncured sheet of the vibration suppressing rubber layer is simultaneously applied to one side of the carcass ply. A method for manufacturing a pneumatic run-flat tire is proposed, which is rolled and previously integrated with a carcass ply and a vibration suppressing rubber layer , and then the composite sheet is subjected to a tire forming step. According to this method, one sheet of vibration suppressing rubber layer is added as a tire molding member in the present invention. However, according to the above-described method of the present invention, the present invention has almost the same facilities and man-hours as in the past. There is an advantage that a pneumatic run flat tire can be manufactured.
[0017]
Pneumatic tires are used by being mounted on standard rims defined in standards issued by JATMA (Japan), TRA (US), ETRTO (Europe), etc., depending on the size of each tire. Usually called a regular rim.
[0018]
In accordance with this common designation in this specification, “regular rim” refers to a standard rim in the applicable size defined in the 2000 version of YEAR BOOK issued by the United States Tire and Rim Association TRA. Similarly, “regular load” and “regular internal pressure” refer to the maximum load and the air pressure corresponding to the maximum load in the applicable size and ply rating defined in the 2000 version of YEAR BOOK issued by TRA in the United States. Point to. Here, the load is the maximum load (maximum load capacity) of a single wheel at the applicable size described in the following standard, and the internal pressure is the maximum load of a single wheel at the applicable size described in the following standard ( The rim is the standard rim (or “Approved Rim” or “Recommended Rim”) in the applicable size described in the following standards.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
[0020]
1 and 2 show a run-flat tire according to an embodiment of the present invention in a cross-sectional view of the left half. The run flat tire of this embodiment is for passenger cars and is a pneumatic run flat tire of size 225 / 60R16 (radial structure tire). FIG. 1 (type A) shows that the vibration suppressing rubber is the carcass inner surface and the side reinforcing rubber. Between the layers, it extends beyond the boundary surface between the side reinforcing rubber layer and the carcass layer to the radially outer side and the radially inner side, and the vibration suppressing rubber layer exists in a cross-sectional form that completely wraps the side reinforcing rubber layer. In FIG. 2 (assumed to be type B), the vibration suppression rubber is between the carcass inner surface and the side reinforcing rubber layer, and is partially interposed around the center in the tire radial direction at the boundary surface between the side reinforcing rubber layer and the carcass layer. The existing cross-sectional form is formed. In the tire cross section of FIG. 1 (type A), vibration suppression rubber is necessarily interposed between the side reinforcing rubber layer and the carcass layer, but in the tire cross section of FIG. 2 (type B), the side reinforcing rubber layer and the carcass layer are The vibration suppressing rubber is only interposed in the central portion between the two.
[0021]
In order to show an embodiment of the present invention, a run-flat tire having a vibration suppressing rubber layer arrangement structure and material characteristics shown in Table 1 was prototyped from the inner side of the innermost ply of the tire carcass to the shoulder region. Embodiments (1) to (4) have a vibration suppressing rubber layer, but the tires (2) to (4) have a structure of type A (FIG. 1) in which the vibration suppressing rubber layer wraps the side reinforcing layer. The implementation tire {circle around (1)} has a structure of type B (FIG. 2) in which the vibration suppressing rubber layer is partially interposed at the center of the boundary between the carcass layer and the side reinforcing rubber layer. The hardness of the vibration suppression rubber of each tire is 55 for the implementation tires (1) and (4), and 80 and 30 for the implementation tires (2) and (3), respectively. The side-reinforcing rubber layer having a crescent-shaped cross section used for the tires was made with the formulation disclosed in JP-A-11-245636 and had a hardness of 90. The hardness of the coated rubber of the innermost carcass of all prototype tires is 40.
[0022]
[Table 1]
In order to confirm the effect of the present invention, the run-flat running life, the ride comfort test, and the road noise measurement were performed for each tire prototyped according to the above specifications. An index is shown in Table 2. Here, the relative evaluation index means that the larger the number, the better, and the smaller the number, the worse the relative evaluation index.
[0024]
[Table 2]
The run-flat running performance of the tire of the present invention is substantially the same as or better than the performance of the conventional tire. The tire with the vibration suppression rubber layer of the present invention is improved in road noise level and ride comfort. In particular, as seen in the implementation tires (2) to (4), the A type vibration suppression rubber is the side. It can be seen that the effect is remarkable when the boundary surface between the reinforcing rubber layer and the carcass layer is completely covered. Furthermore, in the tire of Example (4) in which the hardness of the vibration suppressing rubber layer is within the preferable range of 35 to 75 of the present invention, it was demonstrated that the effect of improving road noise and riding comfort is the maximum.
[0026]
The tire performance test method in the present embodiment is as follows.
[0027]
<Run-flat running life>
The test tire is assembled on a regular rim, the internal pressure is zero, a regular load of 375 Kgf is applied, it is pressed against a drum tester with a diameter of 1700 mm, and it runs at a speed of 80 km / h until a failure occurs. Lifespan was evaluated.
[0028]
<Road noise (road noise) test>
A test tire of size 175 / 70R14 is assembled on a regular rim and mounted on a sedan type passenger car with a displacement of 2000 cc, and all four wheels get on and run a road noise evaluation test course at a speed of 60 km / h. A collecting microphone was attached to the center of the back of the back of the driver's seat, and the total sound pressure (decibel) at frequencies of 100 to 500 Hz and 300 to 500 Hz was measured. This measured value is displayed as an index with the conventional tire as 100, and the higher the index, the better the road noise.
[0029]
<Riding comfort evaluation>
On a steel test drum with a 2 cm width and a 1 cm height attached to a 2 m outer diameter tire test drum, a normal load is applied and the test tire is pressed to rotate the drum. The vibration waveform in the up-and-down load direction when riding over is measured with an accelerometer, the reciprocal of the amplitude of the first period is obtained, and the conventional tire is displayed as an index with 100. The larger the index, the better the ride comfort.
[0030]
【The invention's effect】
As described above, the pneumatic run-flat tire of the present invention has a vibration suppressing rubber layer interposed between the side reinforcing layer and the carcass inner surface, so that the ride comfort is good during normal driving and the road noise is suppressed. This is an excellent tire that maintains the performance of a comfortable passenger car tire and that is safe and reliable for run-flat running when the internal pressure drops due to puncture.
[Brief description of the drawings]
FIG. 1 is a half sectional view of a pneumatic run-flat tire according to one embodiment (type A) of the present invention.
FIG. 2 is a half sectional view of a pneumatic run-flat tire according to another embodiment (type B) of the present invention.
[Explanation of symbols]
1A Bead core
Claims (10)
前記カーカスのサイド領域のタイヤ軸方向外側に配置されてタイヤサイド部を構成するサイドゴム層と、
前記カーカスのクラウン領域のタイヤ径方向外側に配置されてトレッド部を構成するトレッドゴム層と、
前記トレッドゴム層とカーカスのクラウン領域の間に配置される少なくとも１枚のベルトプライからなるベルトと、
前記カーカスのタイヤ内方全面に配置されるインナーライナーと、
前記一方のビードコアから他方のビードコアへ延びるカーカス本体部分と前記ビードコアに巻き上げられる巻上部分との間に配置されるビードフィラー層と、
を備えた空気入りランフラットタイヤであって、
前記カーカスのタイヤサイド部からショルダー領域の内側にかけて、タイヤ回転軸に沿った断面形状が略三日月形である、少なくとも１層の補強ゴム層を有するサイド補強層を有し、
前記カーカスのタイヤサイド部からショルダー領域の内側にかけて、前記タイヤカーカスと前記サイド補強層との間に振動抑制ゴム層を配設し、
前記振動抑制ゴム層のタイヤ回転軸に沿った断面の厚みが、タイヤ径方向の上端部と下端部を除いて一定である空気入りランフラットタイヤ。A carcass composed of at least one radial carcass ply that is connected in a toroidal shape between a pair of bead cores and whose both ends are wound up from the inside of the tire to the outside of the bead core;
A side rubber layer disposed on the outer side in the tire axial direction of the side region of the carcass and constituting a tire side portion; and
A tread rubber layer disposed on the outer side in the tire radial direction of the crown region of the carcass and constituting a tread portion;
A belt composed of at least one belt ply disposed between the tread rubber layer and the crown region of the carcass;
An inner liner disposed on the entire inner surface of the carcass tire,
A bead filler layer disposed between a carcass main body portion extending from the one bead core to the other bead core and a winding portion wound up on the bead core;
Pneumatic run flat tire with
From the tire side portion of the carcass to the inside of the shoulder region, the cross-sectional shape along the tire rotation axis is a substantially crescent shape, and has a side reinforcing layer having at least one reinforcing rubber layer,
From the tire side portion of the carcass to the inside of the shoulder region, a vibration suppressing rubber layer is disposed between the tire carcass and the side reinforcing layer,
A pneumatic run-flat tire having a constant cross-sectional thickness along the tire rotation axis of the vibration suppressing rubber layer except for an upper end portion and a lower end portion in the tire radial direction .
前記カーカスの最内層プライのコードに被覆ゴムを圧延するカレンダー工程にて、該カーカスプライの片面に前記振動抑制ゴム層の未加硫シートを同時に圧延して、予めカーカスプライと振動抑制ゴム層を一体化した後、該複合シートをタイヤの成形工程へ供することを特徴とする空気入りランフラットタイヤの製造方法。In the manufacturing method of the pneumatic run-flat tire according to any one of claims 1 to 9,
In the calendering process of rolling the covering rubber on the cord of the innermost layer ply of the carcass, the uncured sheet of the vibration suppressing rubber layer is simultaneously rolled on one side of the carcass ply, and the carcass ply and the vibration suppressing rubber layer are previously provided. After the integration, the composite sheet is subjected to a tire forming process, and a method for producing a pneumatic run-flat tire is provided.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000133423A JP4571270B2 (en) | 2000-05-02 | 2000-05-02 | Pneumatic run-flat tire and manufacturing method |
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| Application Number | Priority Date | Filing Date | Title |
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| JP2000133423A JP4571270B2 (en) | 2000-05-02 | 2000-05-02 | Pneumatic run-flat tire and manufacturing method |
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| JP2001315510A JP2001315510A (en) | 2001-11-13 |
| JP4571270B2 true JP4571270B2 (en) | 2010-10-27 |
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| JP2000133423A Expired - Lifetime JP4571270B2 (en) | 2000-05-02 | 2000-05-02 | Pneumatic run-flat tire and manufacturing method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2005280459A (en) * | 2004-03-29 | 2005-10-13 | Sumitomo Rubber Ind Ltd | Run flat tire |
| JP4626331B2 (en) * | 2005-02-18 | 2011-02-09 | 横浜ゴム株式会社 | Pneumatic tire |
| JP4703384B2 (en) * | 2005-11-30 | 2011-06-15 | 株式会社ブリヂストン | Run flat tire |
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| JP2000127709A (en) * | 1998-10-19 | 2000-05-09 | Bridgestone Corp | Pneumatic tire |
| DE19941340A1 (en) * | 1999-08-31 | 2001-03-01 | Dunlop Gmbh | Vehicle tires |
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| JPS54151201A (en) * | 1978-05-10 | 1979-11-28 | Pneumatiques Caoutchouc Mfg | Safety pneumatic tire |
| JPH01278806A (en) * | 1988-05-02 | 1989-11-09 | Sumitomo Rubber Ind Ltd | Safe tire |
| JPH03136904A (en) * | 1989-10-24 | 1991-06-11 | Yokohama Rubber Co Ltd:The | Pneumatic radial tire |
| JPH05139111A (en) * | 1991-11-20 | 1993-06-08 | Yokohama Rubber Co Ltd:The | Pneumatic radial tire |
| JPH06171303A (en) * | 1992-12-08 | 1994-06-21 | Bridgestone Corp | Pneumatic radial tire |
| JPH07126442A (en) * | 1993-10-29 | 1995-05-16 | Sumitomo Chem Co Ltd | Rubber composition and method for bonding rubber to steel cord |
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