JP3777319B2

JP3777319B2 - Pneumatic tire

Info

Publication number: JP3777319B2
Application number: JP2001316927A
Authority: JP
Inventors: 全一郎信田; 祐二遠松
Original assignee: Yokohama Rubber Co Ltd
Current assignee: Yokohama Rubber Co Ltd
Priority date: 2001-10-15
Filing date: 2001-10-15
Publication date: 2006-05-24
Anticipated expiration: 2021-10-15
Also published as: JP2003118317A

Description

【０００１】
【発明の属する技術分野】
本発明は、トレッド表面輪郭を複数の円弧を組み合わせて構成した空気入りタイヤに関し、さらに詳しくは、接地圧分布の適正化を図った空気入りタイヤに関する。
【０００２】
【従来の技術】
タイヤの接地圧分布は、直進時に略均一であっても、旋回時にはタイヤのショルダー部、特に車両装着時に外側となるショルダー部で接地圧が高くなり易い。そのため、後輪と比較して高い旋回力が要求される前輪においては、タイヤのショルダー部、特に車両装着時に外側となるショルダー部が早期に摩耗し易く、摩耗寿命が短くなるという問題があった。
【０００３】
また、旋回時及び制動時においては、トレッドに大きな剪断力が加わることによりトレッドパターンに変形が生じ、ブロックやリブ内の接地圧分布が不均一になり易いため、不均一な摩耗が発生し易い。そのため、摩耗が進展した際にトレッド表面の凹凸が増加し、転動時にトレッドのブロックが路面に接触する際の衝撃力が増加するため、摩耗時の騒音が増加するという問題があった。
【０００４】
【発明が解決しようとする課題】
本発明の目的は、接地圧分布を適正化することで、耐ショルダー摩耗性を向上すると共に、摩耗時の騒音を低減することを可能にした空気入りタイヤを提供することにある。
【０００５】
【課題を解決するための手段】
上記目的を達成するための本発明の空気入りタイヤは、トレッドにタイヤ周方向に延びる少なくとも２本の直線状の太溝を有し、タイヤ中心からタイヤ軸方向に最も離れた両側に位置する太溝の中心よりタイヤ軸方向両外側にショルダー領域を有し、これらショルダー領域に挟まれたセンター領域を有する空気入りタイヤにおいて、
前記センター領域内で前記ショルダー領域に隣接し、かつタイヤ周方向に延びる直線状の溝によってタイヤ中心側から区分されると共に、そのトレッド表面輪郭を形成する円弧が前記センター領域のタイヤ中心側のトレッド表面輪郭を形成する円弧と交差するサブセンター領域を、タイヤ中心を境として車両装着時に内側となる片側のみに形成し、
前記サブセンター領域を有する側で、前記センター領域のトレッド表面輪郭を形成する円弧であってタイヤ中心を通る円弧をＡ１１とし、前記サブセンター領域のトレッド表面輪郭を形成する円弧をＡ２１とし、前記ショルダー領域のトレッド表面輪郭を形成する円弧であって最もタイヤ軸方向内側にある円弧をＡ３１としたとき、円弧Ａ１１と円弧Ａ２１とが互いに交差し、円弧Ａ２１及び円弧Ａ３１が円弧Ａ１１の延長線よりタイヤ径方向外側に位置し、円弧Ａ２１と円弧Ａ３１とが互いに交差し、円弧Ａ３１が円弧Ａ２１の延長線よりタイヤ径方向内側に位置し、
前記サブセンター領域を有しない側で、前記センター領域のトレッド表面輪郭を形成する円弧であってタイヤ中心を通る円弧をＡ１１’とし、前記ショルダー領域のトレッド表面輪郭を形成する円弧であって最もタイヤ軸方向内側にある円弧をＡ３１’としたとき、円弧Ａ１１’の曲率半径Ｒ１１’が円弧Ａ１１の曲率半径Ｒ１１より大きく、円弧Ａ３１’と円弧Ａ１１’とが互いに交差し、円弧Ａ３１’が円弧Ａ１１’の延長線よりタイヤ径方向外側に位置すると共に、
前記ショルダー領域をタイヤ軸方向両側で互いに異なる大きさとし、車両装着時に外側となるショルダー領域を車両装着時に内側となるショルダー領域より大きくしたことを特徴とするものである。
【０００６】
このようにトレッドにセンター領域、サブセンター領域及びショルダー領域を設け、その円弧の関係を上記の如く設定することにより、接地圧分布が適正化され、特にショルダー部への接地圧集中が抑制されるので、耐ショルダー摩耗性が向上し、摩耗寿命が向上する。また、トレッドに形成されたブロック内においても接地圧が不均一になり難く、ブロックが不均一に摩耗し難くなるので、摩耗時の騒音を低減することができる。
【０００７】
本発明では、前記サブセンター領域を、タイヤ中心を境として片側のみに形成し、前記サブセンター領域を有しない側で、前記センター領域のトレッド表面輪郭を形成する円弧であってタイヤ中心を通る円弧をＡ１１’とし、前記ショルダー領域のトレッド表面輪郭を形成する円弧であって最もタイヤ軸方向内側にある円弧をＡ３１’としたとき、円弧Ａ１１’の曲率半径Ｒ１１’が円弧Ａ１１の曲率半径Ｒ１１より大きく、円弧Ａ３１’と円弧Ａ１１’とが互いに交差し、円弧Ａ３１’が円弧Ａ１１’の延長線よりタイヤ径方向外側に位置する。このようにサブセンター領域をトレッドの片側のみに形成した場合も、上記同様に接地圧分布の適正化が可能である。
【０００８】
前記ショルダー領域はタイヤ軸方向両側で互いに異なる大きさとし、車両装着時に外側となるショルダー領域を車両装着時に内側となるショルダー領域より大きくする。これにより、ショルダー領域に形成されるブロックやリブの剪断剛性及び曲げ剛性を車両特性に合わせて適正化することができる。つまり、旋回時や制動時にトレッドに大きな剪断力が加わる際のトレッド変形に対応するように接地圧分布が適正化されるので、耐ショルダー摩耗性を更に向上し、摩耗時の騒音を更に低減することが可能になる。
【０００９】
【発明の実施の形態】
以下、本発明の構成について添付の図面を参照して詳細に説明する。
【００１０】
図１は本発明の実施形態からなる空気入りタイヤを概略的に示すものである。この空気入りタイヤは、トレッド１にタイヤ周方向に延びる少なくとも２本の直線状の太溝２，２を有し、タイヤ中心ＣＬからタイヤ軸方向に最も離れた両側に位置する太溝２，２の中心よりタイヤ軸方向両外側にショルダー領域Ｓ１，Ｓ２を有し、これらショルダー領域Ｓ１，Ｓ２に挟まれたセンター領域Ｃを有している。このトレッド１には、太溝２，２に加えて、一方の太溝２とタイヤ中心ＣＬとの間に細溝３が設けられ、他方の太溝２よりタイヤ軸方向外側の位置に細溝３が設けられている。つまり、この空気入りタイヤは左右非対称のトレッドパターンを構成している。
【００１１】
上記空気入りタイヤでは、センター領域Ｃ内でショルダー領域Ｓ１に隣接し、かつタイヤ周方向に延びる直線状の細溝３によってタイヤ中心側から区分されたサブセンター領域ＳＣが、タイヤ中心ＣＬを境として片側のみに形成されている。サブセンター領域ＳＣをタイヤ中心側から区分する直線状の溝は太溝及び細溝のいずれであっても良い。また、センター領域Ｃに他の太溝や細溝を設けたり、ショルダー領域Ｓ１，Ｓ２に他の細溝を設けても良い。ここで、太溝とは溝幅がタイヤの呼び幅（ｍｍ）の２％以上の溝であり、細溝とは溝幅がタイヤの呼び幅（ｍｍ）の２％未満の溝である。これら溝はタイヤ周方向に直線状に延長するものであり、僅かであればタイヤ幅方向に振幅していても良いが、実質的な直線であることが好ましい。
【００１２】
サブセンター領域ＳＣを有する側では、センター領域Ｃのトレッド表面輪郭を形成する円弧であってタイヤ中心ＣＬを通る円弧をＡ１１とし、サブセンター領域ＳＣのトレッド表面輪郭を形成する円弧をＡ２１とし、ショルダー領域Ｓ１のトレッド表面輪郭を形成する円弧であって最もタイヤ軸方向内側にある円弧をＡ３１とする。これら円弧Ａ１１，Ａ２１，Ａ３１はそれぞれ曲率半径Ｒ１１，Ｒ２１，Ｒ３１を有している。このとき、円弧Ａ１１と円弧Ａ２１とは互いに交差し、円弧Ａ２１及び円弧Ａ３１は円弧Ａ１１の延長線よりタイヤ径方向外側に位置し、更には、円弧Ａ２１と円弧Ａ３１とは互いに交差し、円弧Ａ３１は円弧Ａ２１の延長線よりタイヤ径方向内側に位置している。特に、円弧Ａ１１と円弧Ａ２１とは周方向溝内で交差することが好ましく、円弧Ａ２１と円弧Ａ３１とは周方向溝内で交差することが好ましい。
【００１３】
円弧Ａ１１，Ａ２１，Ａ３１を上記のように設定することにより、接地圧分布が適正化され、特にショルダー部への接地圧集中が抑制されるので、耐ショルダー摩耗性が向上し、摩耗寿命が向上する。また、トレッド１に形成されたブロック内においても接地圧が不均一になり難く、ブロックが不均一に摩耗し難くなるので、摩耗時の騒音を低減することができる。
【００１４】
これら円弧Ａ１１，Ａ２１，Ａ３１の関係を満足する限りにおいて、センター領域Ｃのトレッド表面輪郭は、複数の円弧Ｒ１１，Ｒ１２，Ｒ１３等にて構成されても良い。これらの円弧Ｒ１１，Ｒ１２，Ｒ１３等は滑らかに繋がっても交差しても良い。また、円弧Ａ１１，Ａ２１，Ａ３１の関係を満足する限りにおいて、ショルダー領域Ｓ１のトレッド表面輪郭は、複数の円弧Ｒ３１，Ｒ３２，Ｒ３３等にて構成されても良い。これらの円弧Ｒ３２，Ｒ３３等は円弧Ｒ３１の延長線よりタイヤ径方向内側に位置することが望ましい。
【００１５】
一方、サブセンター領域ＳＣを有しない側では、センター領域Ｃのトレッド表面輪郭を形成する円弧であってタイヤ中心ＣＬを通る円弧をＡ１１’とし、ショルダー領域Ｓ２のトレッド表面輪郭を形成する円弧であって最もタイヤ軸方向内側にある円弧をＡ３１’とする。これら円弧Ａ１１’，Ａ３１’はそれぞれ曲率半径Ｒ１１’，Ｒ３１’を有している。このとき、円弧Ａ１１’の曲率半径Ｒ１１’は円弧Ａ１１の曲率半径Ｒ１１より大きく、円弧Ａ３１’と円弧Ａ１１’とは互いに交差し、円弧Ａ３１’は円弧Ａ１１’の延長線よりタイヤ径方向外側に位置している。特に、円弧Ａ３１’と円弧Ａ１１’とは周方向溝内で交差することが好ましい。
【００１６】
円弧Ａ１１’，Ａ３１’を上記のように設定することにより、前述の如く適正化された接地圧分布を維持し、耐ショルダー摩耗性を向上すると共に、摩耗時の騒音を低減することができる。
【００１７】
上記空気入りタイヤにおいて、ショルダー領域Ｓ１，Ｓ２はタイヤ軸方向両側で互いに異なる大きさに設定されている。つまり、ショルダー領域Ｓ１，Ｓ２を規定する両外側の太溝２，２のタイヤ中心ＣＬからの距離が互いに異なっており、その結果として、左右のショルダー領域Ｓ１，Ｓ２の幅が互いに異なっている。そして、サブセンター領域ＳＣは小さい方のショルダー領域Ｓ１に隣接して配置されている。
【００１８】
このように一方のショルダー領域Ｓ１を狭くした左右非対称トレッドパターンにおいて、サブセンター領域ＳＣを小さい方のショルダー領域Ｓ１に隣接させることにより、その左右非対称トレッドパターン特有の接地圧分布の不均一を解消することができる。
【００１９】
上記空気入りタイヤは、車両装着方向に拘らず接地圧分布の適正化が可能であるが、特に、ショルダー領域Ｓ１，Ｓ２をタイヤ軸方向両側で互いに異なる大きさとした左右非対称トレッドパターンを構成し、車両装着時に外側となるショルダー領域Ｓ２を車両装着時に内側となるショルダー領域Ｓ１より大きくした場合に、顕著な作用効果が得られる。つまり、旋回時や制動時にトレッド１に大きな剪断力が加わる際のトレッド変形に対応するように接地圧分布が適正化されるので、耐ショルダー摩耗性を更に向上し、摩耗時の騒音を更に低減することができる。
【００２０】
本発明によれば、例えば、図２に示す接地圧分布を有する空気入りタイヤにおいて、トレッド表面輪郭を形成する円弧を適宜変更することにより、図３に示す接地圧分布を有する空気入りタイヤを得ることができる。
【００２１】
【実施例】
タイヤサイズを２１５／６５Ｒ１５９６Ｈとし、下記プロファイルを有する従来タイヤ１，２及び本発明タイヤ１及び比較タイヤ１〜３をそれぞれ製作した。
【００２２】
従来タイヤ１：
図４に示すプロファイルを構成し、その寸法を表１の通りにした。つまり、サブセンター領域を設けず、円弧Ａ１１と円弧Ａ３１とを滑らかに繋いだ。
【００２３】
従来タイヤ２：
図５に示すプロファイルを構成し、その寸法を表１の通りにした。つまり、センター領域の両側にサブセンター領域を設け、円弧Ａ１１と円弧Ａ２１とが周方向溝内で交差し、円弧Ａ２１及び円弧Ａ３１が円弧Ａ１１の延長線よりタイヤ径方向外側に位置し、円弧Ａ２１と円弧Ａ３１とが周方向溝内で交差するものの、円弧Ａ３１が円弧Ａ２１の延長線よりタイヤ径方向外側に位置するように構成した。
【００２４】
比較タイヤ１：
図６に示すプロファイルを構成し、その寸法を表１の通りにした。つまり、センター領域の両側にサブセンター領域を設け、円弧Ａ１１と円弧Ａ２１とが周方向溝内で交差し、円弧Ａ２１及び円弧Ａ３１が円弧Ａ１１の延長線よりタイヤ径方向外側に位置し、円弧Ａ２１と円弧Ａ３１とが周方向溝内で交差し、円弧Ａ３１が円弧Ａ２１の延長線よりタイヤ径方向内側に位置するように構成した。
【００２５】
比較タイヤ２：
図７に示すプロファイルを構成し、その寸法を表１の通りにした。つまり、センター領域の片側にサブセンター領域を設け、円弧Ａ１１と円弧Ａ２１とが周方向溝内で交差し、円弧Ａ２１及び円弧Ａ３１が円弧Ａ１１の延長線よりタイヤ径方向外側に位置し、円弧Ａ２１と円弧Ａ３１とが周方向溝内で交差し、円弧Ａ３１が円弧Ａ２１の延長線よりタイヤ径方向内側に位置するように構成した。また、サブセンター領域を有しない側では、円弧Ａ１１’の曲率半径Ｒ１１’が円弧Ａ１１の曲率半径Ｒ１１より大きく、円弧Ａ３１’と円弧Ａ１１’とが周方向溝内で交差し、円弧Ａ３１’が円弧Ａ１１’の延長線よりタイヤ径方向外側に位置するように構成した。車両装着時には、サブセンター領域の反対側が車両外側に配置されるようにした。
【００２６】
本発明タイヤ１：
図８に示すプロファイルを構成し、その寸法を表１の通りにした。つまり、サブセンター領域に隣接しないショルダー領域を大きくし、サブセンター領域に隣接するショルダー領域を小さくしたこと以外は、比較タイヤ２と同じ構成にした。車両装着時には、大きい方のショルダー領域が車両外側に配置されるようにした。
【００２７】
比較タイヤ３：
本発明タイヤ１と同じ構成とし、車両装着時の位置を本発明タイヤ１とは逆にした。つまり、車両装着時には、小さい方のショルダー領域が車両外側に配置されるようにした。
【００２８】
【表１】

【００２９】
上記試験タイヤをそれぞれリムサイズ６ＪＪ×１５のホイールに組付け、内圧２３０ｋＰａとし、市街地、高速道路、郊外、山岳路を含む所定のコースを交通の流れに合わせて１００００ｋｍ走行した後、下記評価方法により耐ショルダー摩耗性及び摩耗時騒音を評価し、その結果を表２に示した。
【００３０】
耐ショルダー摩耗性：
上記条件にて走行後、左右前輪のセンター部摩耗量Ｄｃとショルダー部摩耗量Ｄｓを測定し、その比率Ｄｃ／Ｄｓを求めた。具体的には、センター部摩耗量Ｄｃは、センター領域を略５等分するポイント６点のうち両端を除いたポイント４点について周上４ヶ所で摩耗量を測定し、その平均値より求めた。ショルダー部摩耗量Ｄｓは、各ショルダー領域を略３等分するポイント４点のうち、それぞれトレッドセンター側のポイント３点について周上４ヶ所で摩耗量を測定し、その平均値より求めた。そして、比率Ｄｃ／Ｄｓは、左右前輪の平均値とした。評価結果は、従来タイヤ２の比率Ｄｃ／Ｄｓを１００とする指数にて示した。この指数値が大きいほど耐ショルダー摩耗性が優れていることを意味する。
【００３１】
摩耗時騒音：
上記条件にて走行後、テストコースにて５名のテストドライバーが官能評価を行った。評価結果は、従来タイヤ２の評価を１００とする指数にて示した。この指数値が大きいほど摩耗時騒音が少ないことを意味する。
【００３２】
【表２】

【００３３】
この表２から判るように、本発明タイヤ１は従来タイヤ１，２に比べて耐ショルダー摩耗性に優れ、しかも摩耗時の騒音が少なかった。
【００３４】
【発明の効果】
以上説明したように本発明によれば、トレッドにタイヤ周方向に延びる少なくとも２本の直線状の太溝を有し、タイヤ中心からタイヤ軸方向に最も離れた両側に位置する太溝の中心よりタイヤ軸方向両外側にショルダー領域を有し、これらショルダー領域に挟まれたセンター領域を有する空気入りタイヤにおいて、
センター領域内でショルダー領域に隣接し、かつタイヤ周方向に延びる直線状の溝によってタイヤ中心側から区分されると共に、そのトレッド表面輪郭を形成する円弧が前記センター領域のタイヤ中心側のトレッド表面輪郭を形成する円弧と交差するサブセンター領域を、タイヤ中心を境として車両装着時に内側となる片側のみに形成し、
サブセンター領域を有する側で、センター領域のトレッド表面輪郭を形成する円弧であってタイヤ中心を通る円弧をＡ１１とし、サブセンター領域のトレッド表面輪郭を形成する円弧をＡ２１とし、ショルダー領域のトレッド表面輪郭を形成する円弧であって最もタイヤ軸方向内側にある円弧をＡ３１としたとき、円弧Ａ１１と円弧Ａ２１とが互いに交差し、円弧Ａ２１及び円弧Ａ３１が円弧Ａ１１の延長線よりタイヤ径方向外側に位置し、円弧Ａ２１と円弧Ａ３１とが互いに交差し、円弧Ａ３１が円弧Ａ２１の延長線よりタイヤ径方向内側に位置し、
サブセンター領域を有しない側で、センター領域のトレッド表面輪郭を形成する円弧であってタイヤ中心を通る円弧をＡ１１’とし、ショルダー領域のトレッド表面輪郭を形成する円弧であって最もタイヤ軸方向内側にある円弧をＡ３１’としたとき、円弧Ａ１１’の曲率半径Ｒ１１’が円弧Ａ１１の曲率半径Ｒ１１より大きく、円弧Ａ３１’と円弧Ａ１１’とが互いに交差し、円弧Ａ３１’が円弧Ａ１１’の延長線よりタイヤ径方向外側に位置すると共に、
ショルダー領域をタイヤ軸方向両側で互いに異なる大きさとし、車両装着時に外側となるショルダー領域を車両装着時に内側となるショルダー領域より大きくするようにしたから、接地圧分布を適正化することができ、その結果として、耐ショルダー摩耗性を向上すると共に、摩耗時の騒音を低減することができる。
【図面の簡単な説明】
【図１】本発明の空気入りタイヤの子午線断面の輪郭を示す概略図である。
【図２】従来の空気入りタイヤの接地圧分布を示すグラフである。
【図３】本発明の空気入りタイヤの接地圧分布を示すグラフである。
【図４】従来タイヤ１の子午線断面の輪郭要部を示す概略図である。
【図５】従来タイヤ２の子午線断面の輪郭要部を示す概略図である。
【図６】比較タイヤ１の子午線断面の輪郭要部を示す概略図である。
【図７】比較タイヤ２の子午線断面の輪郭要部を示す概略図である。
【図８】本発明タイヤ１の子午線断面の輪郭要部を示す概略図である。
【符号の説明】
１トレッド
２太溝
３細溝
Ｃセンター領域
Ｓ１，Ｓ２ショルダー領域
ＳＣサブセンター領域
ＣＬタイヤ中心
Ａ１１，Ａ２１，Ａ３１，Ａ１１’，Ａ３１’円弧
Ｒ１１，Ｒ２１，Ｒ３１，Ｒ１１’，Ｒ３１’曲率半径[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire in which a tread surface contour is configured by combining a plurality of arcs, and more particularly to a pneumatic tire in which contact pressure distribution is optimized.
[0002]
[Prior art]
Even if the tire contact pressure distribution is substantially uniform when going straight, the contact pressure tends to be high at the shoulder portion of the tire when turning, particularly at the shoulder portion outside when mounted on the vehicle. For this reason, the front wheels that require a high turning force compared to the rear wheels have a problem that the shoulder portion of the tire, particularly the outer shoulder portion when worn on the vehicle, tends to wear out early and the wear life is shortened. .
[0003]
Also, during turning and braking, the tread pattern is deformed by applying a large shearing force to the tread, and the contact pressure distribution in the blocks and ribs tends to be non-uniform, so non-uniform wear tends to occur. . Therefore, the unevenness of the tread surface increases when wear progresses, and the impact force when the tread block contacts the road surface during rolling increases, resulting in an increase in noise during wear.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a pneumatic tire capable of improving shoulder wear resistance and reducing noise during wear by optimizing the contact pressure distribution.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a pneumatic tire according to the present invention has at least two straight thick grooves extending in the tire circumferential direction on a tread, and is positioned on both sides farthest from the tire center in the tire axial direction. In a pneumatic tire having a shoulder region on both outer sides in the tire axial direction from the center of the groove and having a center region sandwiched between these shoulder regions,
Adjacent to the shoulder region in the center region, and the tire circumferential direction is divided from the tire center side by the linear groove extending Rutotomoni arc to form the tread surface contour of the tire center side of the center region tread A sub-center region that intersects with the arc that forms the surface contour is formed only on one side that is the inside when the vehicle is mounted , with the tire center as the boundary ,
On the side having the sub-center region, an arc that forms a tread surface contour of the center region and passes through the tire center is A11, and an arc that forms the tread surface contour of the sub-center region is A21, and the shoulder When the arc that forms the tread surface contour of the region and that is the innermost in the tire axial direction is A31, the arc A11 and the arc A21 intersect with each other, and the arc A21 and the arc A31 are extended from the arc A11. Located on the radially outer side, the arc A21 and the arc A31 intersect each other, the arc A31 is located on the inner side in the tire radial direction from the extension line of the arc A21 ,
An arc that forms the tread surface contour of the center region on the side that does not have the sub-center region and that passes through the tire center is A11 ′, and is the arc that forms the tread surface contour of the shoulder region and is the most tire When the arc on the inner side in the axial direction is A31 ′, the radius of curvature R11 ′ of the arc A11 ′ is larger than the radius of curvature R11 of the arc A11, the arc A31 ′ and the arc A11 ′ intersect each other, and the arc A31 ′ is the arc A11. It is located on the outer side in the tire radial direction from the extension line of '
The shoulder regions are different in size on both sides in the tire axial direction, and the shoulder region on the outer side when the vehicle is mounted is larger than the shoulder region on the inner side when the vehicle is mounted .
[0006]
Thus, by providing the center area, the sub-center area, and the shoulder area in the tread and setting the relationship of the arcs as described above, the contact pressure distribution is optimized, and in particular, the contact pressure concentration on the shoulder portion is suppressed. Therefore, the shoulder wear resistance is improved and the wear life is improved. Also, the contact pressure is less likely to be uneven in the block formed on the tread, and the block is less likely to be worn unevenly, so that noise during wear can be reduced.
[0007]
In the present invention, the sub-center region is formed only on one side with the tire center as a boundary, and an arc that forms a tread surface contour of the center region on the side that does not have the sub-center region and passes through the tire center Is A11 ′, and the arc that forms the tread surface contour of the shoulder region and that is the innermost in the tire axial direction is A31 ′, the radius of curvature R11 ′ of the arc A11 ′ is greater than the radius of curvature R11 of the arc A11. Largely, the arc A31 ′ and the arc A11 ′ intersect each other, and the arc A31 ′ is located on the outer side in the tire radial direction from the extension line of the arc A11 ′ . Even when the sub-center region is formed only on one side of the tread as described above, the contact pressure distribution can be optimized as described above.
[0008]
The shoulder regions have different sizes on both sides in the tire axial direction, and the shoulder region on the outer side when the vehicle is mounted is larger than the shoulder region on the inner side when the vehicle is mounted . Thereby, the shear rigidity and bending rigidity of the block and rib which are formed in a shoulder area | region can be optimized according to a vehicle characteristic. In other words, since the contact pressure distribution is optimized to cope with tread deformation when a large shear force is applied to the tread during turning or braking, shoulder wear resistance is further improved and noise during wear is further reduced. It becomes possible.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
[0010]
FIG. 1 schematically shows a pneumatic tire according to an embodiment of the present invention. This pneumatic tire has at least two linear thick grooves 2 and 2 extending in the tire circumferential direction on the tread 1, and the thick grooves 2 and 2 positioned on both sides farthest in the tire axial direction from the tire center CL. Shoulder regions S1 and S2 on both outer sides in the tire axial direction from the center of the tire, and a center region C sandwiched between the shoulder regions S1 and S2. In addition to the thick grooves 2 and 2, the tread 1 is provided with a narrow groove 3 between the one thick groove 2 and the tire center CL, and the narrow groove is located at a position on the outer side in the tire axial direction from the other thick groove 2. 3 is provided. That is, this pneumatic tire constitutes a left-right asymmetric tread pattern.
[0011]
In the pneumatic tire, the sub-center region SC that is adjacent to the shoulder region S1 in the center region C and that is divided from the tire center side by the linear narrow groove 3 that extends in the tire circumferential direction has the tire center CL as a boundary. It is formed only on one side . The straight groove that divides the sub-center region SC from the tire center side may be either a thick groove or a thin groove. Further, other thick grooves or narrow grooves may be provided in the center region C, or other narrow grooves may be provided in the shoulder regions S1 and S2. Here, the thick groove is a groove whose groove width is 2% or more of the nominal width (mm) of the tire, and the narrow groove is a groove whose groove width is less than 2% of the nominal width (mm) of the tire. These grooves extend linearly in the tire circumferential direction, and if they are small, they may swing in the tire width direction, but are preferably substantially straight.
[0012]
On the side having the sub-center region SC, an arc that forms the tread surface contour of the center region C and passes through the tire center CL is A11, and an arc that forms the tread surface contour of the sub-center region SC is A21. An arc that forms the tread surface contour of the region S1 and that is the innermost in the tire axial direction is A31. These arcs A11, A21, A31 have radii of curvature R11, R21, R31, respectively. At this time, the arc A11 and the arc A21 intersect each other, the arc A21 and the arc A31 are located on the outer side in the tire radial direction from the extension line of the arc A11, and further, the arc A21 and the arc A31 intersect each other, and the arc A31 Is located on the inner side in the tire radial direction from the extended line of the arc A21. In particular, the arc A11 and the arc A21 preferably intersect within the circumferential groove, and the arc A21 and arc A31 preferably intersect within the circumferential groove.
[0013]
By setting the arcs A11, A21, and A31 as described above, the contact pressure distribution is optimized, and particularly the contact pressure concentration on the shoulder portion is suppressed, so that the shoulder wear resistance is improved and the wear life is improved. To do. Moreover, since the contact pressure is less likely to be uneven in the block formed on the tread 1 and the block is less likely to be worn unevenly, noise during wear can be reduced.
[0014]
As long as the relationship between the arcs A11, A21, and A31 is satisfied, the tread surface contour of the center region C may be configured by a plurality of arcs R11, R12, R13, and the like. These arcs R11, R12, R13, etc. may be smoothly connected or intersected. Further, as long as the relationship between the arcs A11, A21, and A31 is satisfied, the tread surface contour of the shoulder region S1 may be configured by a plurality of arcs R31, R32, R33, and the like. These arcs R32, R33 and the like are preferably located on the inner side in the tire radial direction from the extension line of the arc R31.
[0015]
On the other hand, on the side not having the sub-center region SC, the arc that forms the tread surface contour of the center region C and that passes through the tire center CL is A11 ′, and the arc that forms the tread surface contour of the shoulder region S2. The arc that is at the innermost side in the tire axial direction is A31 ′. These arcs A11 ′ and A31 ′ have radii of curvature R11 ′ and R31 ′, respectively. At this time, the radius of curvature R11 ′ of the arc A11 ′ is larger than the radius of curvature R11 of the arc A11, the arc A31 ′ and the arc A11 ′ intersect each other, and the arc A31 ′ is on the outer side in the tire radial direction from the extension line of the arc A11 ′. positioned. In particular, it is preferable that the arc A31 ′ and the arc A11 ′ intersect in the circumferential groove.
[0016]
By setting the arcs A11 ′ and A31 ′ as described above, the contact pressure distribution optimized as described above can be maintained, shoulder wear resistance can be improved, and noise during wear can be reduced.
[0017]
In the pneumatic tire, the shoulder regions S1 and S2 are set to have different sizes on both sides in the tire axial direction. That is, the distances from the tire center CL of the outer thick grooves 2 and 2 defining the shoulder regions S1 and S2 are different from each other, and as a result, the widths of the left and right shoulder regions S1 and S2 are different from each other. The sub-center region SC is disposed adjacent to the smaller shoulder region S1.
[0018]
In this way, in the left-right asymmetric tread pattern in which one shoulder region S1 is narrowed, the sub-center region SC is adjacent to the smaller shoulder region S1, thereby eliminating the non-uniformity of the contact pressure distribution peculiar to the left-right asymmetric tread pattern. be able to.
[0019]
The pneumatic tire is capable of optimizing the contact pressure distribution regardless of the vehicle mounting direction. In particular, the pneumatic tire has a right and left asymmetric tread pattern in which the shoulder regions S1 and S2 have different sizes on both sides in the tire axial direction. When the shoulder region S2 that is the outer side when the vehicle is mounted is larger than the shoulder region S1 that is the inner side when the vehicle is mounted, a remarkable effect can be obtained. In other words, since the contact pressure distribution is optimized to cope with tread deformation when a large shear force is applied to the tread 1 during turning or braking, the shoulder wear resistance is further improved, and noise during wear is further reduced. can do.
[0020]
According to the present invention, for example, in the pneumatic tire having the contact pressure distribution shown in FIG. 2, the pneumatic tire having the contact pressure distribution shown in FIG. 3 is obtained by appropriately changing the arc forming the tread surface contour. be able to.
[0021]
【Example】
The tire size was 215 / 65R15 96H, and the conventional tires 1 and 2, the present invention tire 1 and the comparative tires 1 to 3 having the following profiles were produced, respectively.
[0022]
Conventional tire 1:
The profile shown in FIG. 4 was constructed and the dimensions were as shown in Table 1. That is, the arc A11 and the arc A31 are smoothly connected without providing the sub-center region.
[0023]
Conventional tire 2:
The profile shown in FIG. 5 was constructed and the dimensions were as shown in Table 1. That is, the sub-center region is provided on both sides of the center region, the arc A11 and the arc A21 intersect in the circumferential groove, the arc A21 and the arc A31 are located on the outer side in the tire radial direction from the extension line of the arc A11, and the arc A21 And the arc A31 intersect in the circumferential groove, but the arc A31 is positioned on the outer side in the tire radial direction from the extension line of the arc A21.
[0024]
Comparative tire 1:
The profile shown in FIG. 6 was constructed and the dimensions were as shown in Table 1. That is, the sub-center region is provided on both sides of the center region, the arc A11 and the arc A21 intersect in the circumferential groove, the arc A21 and the arc A31 are located on the outer side in the tire radial direction from the extension line of the arc A11, and the arc A21 And the arc A31 intersect in the circumferential groove, and the arc A31 is positioned on the inner side in the tire radial direction from the extension line of the arc A21.
[0025]
Comparative tire 2:
The profile shown in FIG. 7 was constructed and the dimensions were as shown in Table 1. In other words, the sub-center region is provided on one side of the center region, the arc A11 and the arc A21 intersect in the circumferential groove, the arc A21 and the arc A31 are located on the outer side in the tire radial direction from the extension line of the arc A11, and the arc A21 And the arc A31 intersect in the circumferential groove, and the arc A31 is positioned on the inner side in the tire radial direction from the extension line of the arc A21. On the side having no sub-center region, the radius of curvature R11 ′ of the arc A11 ′ is larger than the radius of curvature R11 of the arc A11, the arc A31 ′ and the arc A11 ′ intersect in the circumferential groove, and the arc A31 ′ It was comprised so that it might be located in the tire radial direction outer side from the extended line of circular arc A11 '. When the vehicle is mounted, the opposite side of the sub-center area is arranged outside the vehicle.
[0026]
Invention tire 1 :
The profile shown in FIG. 8 was constructed and the dimensions were as shown in Table 1. That is, the same configuration as that of the comparative tire 2 was adopted except that the shoulder region not adjacent to the sub center region was enlarged and the shoulder region adjacent to the sub center region was reduced. When the vehicle is mounted, the larger shoulder area is arranged outside the vehicle.
[0027]
Comparative tire 3 :
The same configuration as the tire 1 of the present invention was used, and the position when the vehicle was mounted was reversed from that of the tire 1 of the present invention. That is, when the vehicle is mounted, the smaller shoulder region is arranged outside the vehicle.
[0028]
[Table 1]

[0029]
Each of the above test tires is assembled to a wheel having a rim size of 6 JJ × 15, an internal pressure is set to 230 kPa, and a predetermined course including an urban area, a highway, a suburb, and a mountain road is run for 10,000 km according to the traffic flow. Shoulder wear and wear noise were evaluated and the results are shown in Table 2.
[0030]
Shoulder wear resistance:
After traveling under the above conditions, the center portion wear amount Dc and the shoulder portion wear amount Ds of the left and right front wheels were measured, and the ratio Dc / Ds was obtained. Specifically, the center portion wear amount Dc was obtained from an average value obtained by measuring the wear amount at four points on the circumference of four points excluding both ends of six points that divide the center region into approximately five equal parts. . The shoulder wear amount Ds was obtained from an average value obtained by measuring the wear amount at four points on the circumference of the three points on the tread center side among the four points that divide each shoulder region into approximately three equal parts. The ratio Dc / Ds was the average value of the left and right front wheels. The evaluation results are shown as an index with the ratio Dc / Ds of the conventional tire 2 being 100. A larger index value means better shoulder wear resistance.
[0031]
Wear noise:
After running under the above conditions, five test drivers performed a sensory evaluation on the test course. The evaluation results are indicated by an index in which the evaluation of the conventional tire 2 is 100. A larger index value means less wear noise.
[0032]
[Table 2]

[0033]
As can be seen from Table 2, the present invention tires 1 is excellent in resistance to shoulder wear resistance as compared with conventional tires 1 and 2, moreover the noise during wear was small.
[0034]
【The invention's effect】
As described above, according to the present invention, the tread has at least two linear thick grooves extending in the tire circumferential direction, and the center of the thick grooves located on both sides farthest from the tire center in the tire axial direction. In a pneumatic tire having a shoulder region on both outer sides in the tire axial direction and having a center region sandwiched between these shoulder regions,
Adjacent to the shoulder region in the center area, and is divided from the tire center side by the linear groove extending in the tire circumferential direction Rutotomoni, tire center side of the tread surface profile of the arc that forms the tread surface contour the center region A sub-center region that intersects with the arc that forms is formed only on one side that is the inner side when the vehicle is mounted , with the tire center as the boundary ,
On the side having the sub-center region, an arc that forms the tread surface contour of the center region and passes through the center of the tire is A11, an arc that forms the tread surface contour of the sub-center region is A21, and the tread surface of the shoulder region When the arc that forms the contour and is the innermost in the tire axial direction is A31, the arc A11 and the arc A21 intersect with each other, and the arc A21 and the arc A31 are on the outer side in the tire radial direction from the extension line of the arc A11. Is located, the arc A21 and the arc A31 intersect each other, the arc A31 is located on the inner side in the tire radial direction from the extension line of the arc A21 ,
An arc that forms the tread surface contour of the center region and passes through the tire center on the side that does not have the sub-center region is A11 ′, and is the arc that forms the tread surface contour of the shoulder region and is the innermost in the tire axial direction. If the arc at A31 ′ is A31 ′, the radius of curvature R11 ′ of the arc A11 ′ is larger than the radius of curvature R11 of the arc A11, the arc A31 ′ and the arc A11 ′ intersect each other, and the arc A31 ′ is an extension of the arc A11 ′. While located on the outside in the tire radial direction from the line,
Since the shoulder area has different sizes on both sides in the tire axial direction and the shoulder area that is outside when the vehicle is mounted is made larger than the shoulder area that is inside when the vehicle is mounted , the contact pressure distribution can be optimized. As a result, shoulder wear resistance can be improved and noise during wear can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic view showing the outline of a meridian cross section of a pneumatic tire of the present invention.
FIG. 2 is a graph showing a contact pressure distribution of a conventional pneumatic tire.
FIG. 3 is a graph showing the contact pressure distribution of the pneumatic tire of the present invention.
FIG. 4 is a schematic view showing a principal part of a contour of a meridian section of a conventional tire 1;
FIG. 5 is a schematic view showing a principal part of a contour of a meridian section of a conventional tire 2;
FIG. 6 is a schematic view showing a main part of the contour of a meridian cross section of a

comparative

tire 1;
FIG. 7 is a schematic view showing a main part of a contour of a meridian cross section of a comparative tire 2;
FIG. 8 is a schematic view showing a principal part of a meridian cross section of the tire 1 of the present invention.
[Explanation of symbols]
1 Tread 2 Thick groove 3 Narrow groove C Center region S1, S2 Shoulder region SC Sub center region CL Tire center A11, A21, A31, A11 ', A31' Arc R11, R21, R31, R11 ', R31' radius of curvature

Claims

The tread has at least two linear thick grooves extending in the tire circumferential direction, and has shoulder regions on both outer sides in the tire axial direction from the centers of the thick grooves located on both sides farthest from the tire center in the tire axial direction. In a pneumatic tire having a center region sandwiched between these shoulder regions,
Adjacent to the shoulder region in the center region, and the tire circumferential direction is divided from the tire center side by the linear groove extending Rutotomoni arc to form the tread surface contour of the tire center side of the center region tread A sub-center region that intersects with the arc that forms the surface contour is formed only on one side that is the inside when the vehicle is mounted , with the tire center as the boundary ,
On the side having the sub-center region, an arc that forms a tread surface contour of the center region and passes through the tire center is A11, and an arc that forms the tread surface contour of the sub-center region is A21, and the shoulder When the arc that forms the tread surface contour of the region and that is the innermost in the tire axial direction is A31, the arc A11 and the arc A21 intersect with each other, and the arc A21 and the arc A31 are extended from the arc A11. Located on the radially outer side, the arc A21 and the arc A31 intersect each other, the arc A31 is located on the inner side in the tire radial direction from the extension line of the arc A21 ,
An arc that forms the tread surface contour of the center region on the side that does not have the sub-center region and that passes through the tire center is A11 ′, and is the arc that forms the tread surface contour of the shoulder region and is the most tire When the arc on the inner side in the axial direction is A31 ′, the radius of curvature R11 ′ of the arc A11 ′ is larger than the radius of curvature R11 of the arc A11, the arc A31 ′ and the arc A11 ′ intersect each other, and the arc A31 ′ is the arc A11. It is located on the outer side in the tire radial direction from the extension line of '
A pneumatic tire characterized in that the shoulder region has different sizes on both sides in the tire axial direction, and the shoulder region on the outer side when the vehicle is mounted is larger than the shoulder region on the inner side when the vehicle is mounted .

The air according to claim 1, wherein the intersection of the arc A11 and the arc A21, the intersection of the arc A21 and the arc A31, and the intersection of the arc A31 'and the arc A11' are respectively located in the circumferential groove. Tires.