JP4873514B2

JP4873514B2 - Pneumatic tire

Info

Publication number: JP4873514B2
Application number: JP2001019451A
Authority: JP
Inventors: 博司中村
Original assignee: Toyo Tire and Rubber Co Ltd
Current assignee: Toyo Tire Corp
Priority date: 2001-01-29
Filing date: 2001-01-29
Publication date: 2012-02-08
Anticipated expiration: 2021-01-29
Also published as: JP2002219909A

Abstract

PROBLEM TO BE SOLVED: To reduce tire noises occurring outside a vehicle and prevent a tire from having uneven wear. SOLUTION: This pneumatic tire includes a plurality of longitudinal grooves 2 extending in the circumference direction R of the tire, on its tread surface 1. In at least one of the grooves, one or more protrusions are placed in the area including the position which is half the depth of the longitudinal groove in their width direction from both or either of the groove walls facing each other within the grounding length in the circumference direction of the tire under a reference load condition. The following equations are set: GP<GD, GP<GL, 0.4×GW<=GS<=0.8×GW, where GP represents the protruding length of the protrusion T in the width direction of the groove, GD represents the length of T in the depth direction of the groove, GL represents the length of T in the length direction of the groove, GS represents the clearance between the two protrusions T facing each other or between one protrusion T and the groove wall 3, and GW represents the width of the groove.

Description

【０００１】
【発明の属する技術分野】
本発明は、トレッド面にタイヤ周方向に延びる複数の縦溝を有する空気入りタイヤにおいて、タイヤ走行時に発生する騒音を低減させると共に、縦溝に隣接する陸部端に発生する偏摩耗いわゆるリバーウェアを改善する空気入りタイヤに関する。
【０００２】
【従来の技術】
タイヤトレッド部は車輌走行中、タイヤ接地部において路面とタイヤの縦溝とによって形成される空洞内を流れる空気の振動いわゆる気柱管共鳴による騒音が発生し易い。
【０００３】
また、カーカスがラジアル配列の空気入りタイヤのベルト層には、弾性の高いスチールコードなどが設けられているので、タイヤトレッド部全体の剛性が高く、剛性が高いトレッド部で局部的に剛性の低いところの縦溝に隣接する陸部端は、タイヤ走行中、その部分が動き易く路面との間のすべり量が大きくなって摩耗が進行して偏摩耗いわゆるリバーウェアが発生し易い。
【０００４】
従来、かかる騒音発生や偏摩耗を防止するため各種の提案がなされているが、両者を同時に改善する発明は提案されていない。
【０００５】
【発明が解決しようとする課題】
この発明の目的は、トレッド面にタイヤ周方向に延びる複数の縦溝を有する空気入りタイヤにおいて、タイヤ走行時に発生する騒音を低減すると共に、縦溝に隣接する陸部端に発生する偏摩耗いわゆるリバーウェアの改善を図ろうとするものである。
【０００６】
ところで、タイヤの車外騒音を低減するには、上記縦溝における気柱管共鳴音だけではなく、タイヤの車外騒音中、大きな騒音因子となっているポンピング作用による騒音に対しても効果を発揮することが重要である。すなわち、タイヤが路面と接地する際、タイヤの接地面には車輌の荷重が作用するが、かかる場合、当該縦溝の両側に位置する各陸部の両壁は、接地により圧縮されて当該縦溝の内側に膨らみ、当該縦溝が閉塞するところまで接近する。そして、タイヤの回転と共にかかる接地状態が解除されていくと、荷重の負荷がなくなることで上記陸部の膨らみが元に戻り、所定の縦溝の断面形状に回復する。この両側の陸部による縦溝への圧縮とその解除は、それらが繰り返されることにより縦溝内には空気が吸排出され、いわゆるポンピング状態を呈するもので、タイヤパターンによる路面への打撃と同じ周波数となり、重なり合って強め合い、これがタイヤの車外騒音の原因として最も寄与の大きいものとなる。気柱管共鳴音の低減を目指した従来の前記技術では、かかるポンピング作用の抑制には効果が乏しく、全体としてタイヤの車外騒音の低減効果が不十分である。
【０００７】
本発明の目的は、タイヤ周方向に延びる縦溝の溝壁から溝幅方向へ突出する突起を用いて、気柱管共鳴音のみならず、タイヤの車外騒音中、大きな騒音の原因となっているポンピング作用による騒音に対しても効果を発揮し、全体としてタイヤの車外騒音の低減を図ることができ、同時にタイヤの偏摩耗防止を図ることができる空気入りタイヤを提供するところにある。
【０００８】
【課題を解決するための手段】
上記課題を解決するため鋭意検討した結果、本発明は、
トレッド面にタイヤ周方向に延びる複数の縦溝を有する空気入りタイヤにおいて、
少なくとも１本の縦溝内において、基準負荷状態でのタイヤ周方向接地長内に、対向する溝壁の両側の溝壁から溝幅方向へ当該縦溝深さの１／２の位置を含む領域に、対向する一対の突出体を１箇所以上配し、
上記突出体溝幅方向の突出長さをＧＰ、
同溝深さ方向の長さをＧＤ、
同溝長さ方向の長さをＧＬ、
当該縦溝内で対向する突出体同士の間隙をＧＳ、
当該縦溝幅をＧＷ
としたとき、
ＧＰ＜ＧＤ、ＧＰ＜ＧＬ、０．４×ＧＷ≦ＧＳ≦０．８×ＧＷ
である空気入りタイヤを採用した。
【０００９】
従って、本発明のタイヤは、少なくとも１本の縦溝内を基準負荷状態でのタイヤ周方向接地長内に、対向する溝壁の両側または片側の溝壁から溝幅方向へ当該縦溝深さの１／２の位置を含む領域に、１箇所以上配した上記突出体が、接地の際に縦溝と路面で構成される気柱管内の振動モードを特定の周波数から断続的或いは連続的に変化する周波数とするため、気柱共鳴音は実質的に消滅することができる。
なお、前記基準負荷状態とは、各タイヤのサイズ毎にＪＩＳ規格に規定されている空気圧とそれに対応する負荷を与えた状態であることを言う。
また、本発明のタイヤは、少なくとも１本の縦溝内において、基準負荷状態でのタイヤ周方向接地長内に、対向する溝壁の両側または片側の溝壁から溝幅方向へ当該縦溝深さの１／２の位置を含む領域に、突出体を１箇所以上配したので、縦溝に隣接する陸部端は、その部分の動きが抑制される。即ち、見かけ上ブロックの縦方向の剛性が大となり、その結果、該陸部端の路面との間のすべり量が抑制されて偏摩耗いわゆるリバーウェアの発生を防止することができる。
【００１０】
さらに、本発明のタイヤは、少なくとも１本の縦溝内において、基準負荷状態でのタイヤ周方向接地長内に、対向する溝壁の両側または片側の溝壁から溝幅方向へ当該縦溝深さの１／２の位置を含む領域に、１箇所以上配されている前記突出体がタイヤ接地時に、対向する突出体同士が接触する。かかる場合、元来トレッドパターンのピッチ数で決まるポンピング周波数を、負荷接地時に前記突出体のタイヤ周方向の配置間隔で決まる周波数に転換することができ、かつランダム化することができる。従って、上記ポンピング周波数はトレッドのブロックパターンのピッチ数と一致しなくなり、タイヤの車外騒音に寄与度の大きい上記パターンがピッチ毎に路面を打撃する時にタイヤが加振されて発生する振動音のピッチ数で決まる１次ピークレベルの低減が可能となる。
【００１１】
なお、上記突出体溝幅方向の突出長さをＧＰ、同溝深さ方向の長さをＧＤ、同溝長さ方向の長さをＧＬ、当該縦溝内で対向する突出体同士の間隙をＧＳ、当該縦溝幅をＧＷとしたとき、
ＧＰ＜ＧＤ、ＧＰ＜ＧＬ、０．４×ＧＷ≦ＧＳ≦０．８×ＧＷ
としたのは、ＧＰ＜ＧＤ又は、ＧＰ＜ＧＬの少なくとも何れかの条件を満たさない場合、タイヤ負荷時に溝の両壁或いは片側の壁が張り出してきて溝幅が狭まる時に、突出体が、圧縮されることによって、突出体が、挫屈を起こし、溝幅の狭まりを充分抑止出来ず、ポンピング作用を抑止することが出来ないからである。
さらに、当該縦溝内で対向する突出体同士の間隙ＧＳを前記のように０．４×ＧＷ≦ＧＳ≦０．８×ＧＷの範囲としたのは、前記間隙ＧＳが０．４×ＧＷ未満であれば、溝容積が減少して溝内の排水効果が悪くなり、湿潤路での走行安定性を害し、間隙ＧＳが０．８×ＧＷを越えれば、突出体による溝幅の狭まりを充分抑止出来ず、ポンピング作用抑制への寄与が少なくなり、その結果、騒音低下への効果が無くなるからである。
【００１２】
また、同一縦溝内において、上記突出体のタイヤ周方向長さＧＬ或いは幅ＧＰが異なる突出体を配することもできる。この場合、突出体を設置する溝両壁のピッチ長、即ち、突出体に加わる力の大きさに応じて突出体の剛性を決めることにより、トレッド部全体に略同等な見かけの剛性を与えることが出来、騒音をより効果的に抑止出来るとともに、トレッド表面部の負荷に対する剛性の均一性から均一な摩耗状態とする効果がある。
【００１３】
上記突出体のタイヤ径方向の配置領域がトレッド接地表面と同一面乃至トレッド接地表面よりもタイヤ径方向内側で、且つ、溝底面よりもタイヤ径方向外側に配することがより好ましい。これは、突出体がトレッドの接地表面よりタイヤ径方向外側にあると、タイヤ走行初期段階で、接地時に働く外力により突出体の先端が損傷したり、突出体の根本にクラックが生じたりして、突出体の効果が充分発揮されず、偏摩耗の起点となりやすいこと、又、溝底面よりもタイヤ径方向外側にするのは接地時に溝底部に排水のための通路を残すためである。
【００１４】
また、同一縦溝内において、
隣り合う上記突出体のタイヤ周方向長さをＬ１、Ｌ２、
隣り合う上記突出体間の間隔をＬＳ、
基準負荷状態でのタイヤ接地周方向長さをＬ３
としたとき、
Ｌ１≦ＬＳ＜Ｌ３、Ｌ２≦ＬＳ＜Ｌ３
であることが望ましい。
【００１５】
隣り合う上記突出体のタイヤ周方向長さＬ１、Ｌ２が隣り合う上記突出体間の間隔ＬＳよりも大であると、突出体によって抑制される溝のポンピング作用の変動が、突出体と突出体の間の間隔ＬＳの領域に於いても影響され、少なくなるため、騒音抑制には効果的であるが、溝内の容積を狭め貯水性とそれに伴う排水性が悪くなり、タイヤの主要な特性の一つである湿潤路に於ける操縦安定性を不安定とすることになる。
また、隣り合う上記突出体間の間隔ＬＳが、基準負荷状態でのタイヤ接地周方向長さＬ３よりも大であると、走行中、突出体がタイヤ接地周方向長内に介在しない部分があるために気柱管共鳴音が発生し、一般に接地周方向長を内に複数個含まれるピッチに対し、そのポンピング作用を抑制することがないから騒音抑制への効果が少なくなるからである。
【００１６】
【発明の実施の形態】
以下、本発明を図に基づき説明する。図１は本発明に係る空気入りタイヤの一実施形態を示すトレッドパターンの概略展開図である。図２は図１におけるＡ−Ａ線の部分断面の概略斜視図である。
【００１７】
１はタイヤトレッド面、２はタイヤトレッド面１をタイヤ周方向Ｒに連なる縦溝、３は縦溝２の溝壁、４は横溝、５、６はそれぞれタイヤの両側に位置するショルダー部の接地端、Ｒはタイヤ周方向、Ｔは突出体、ＧＳは対向する溝壁から溝幅方向へ突出している突出体間の間隙、Ｌ３は基準負荷状態でのタイヤ接地周方向長、１０（点線）は基準負荷状態でのタイヤ周方向接地端である。
【００１８】
本実施形態のタイヤでは、縦溝２は、図１に示される様に、タイヤ赤道線ＣＬの両側に各１本の縦溝２ｂ、２ｃと、さらにその両側にある縦溝２ａ、２ｄで構成されている。そして、縦溝２ｂと縦溝２ｃとの間には横溝４ｂが設けられ、この縦溝２ｂと縦溝２ｃと横溝４ｂとで区分された中央ブロック７ｂが、タイヤ周方向に繰り返し配列されている。一方、縦溝２ａと縦溝２ｂとの間にも同様の横溝４ａが設けられ、さらに縦溝２ｃと縦溝２ｄとの間にも同様の横溝４ｃが設けられ、それぞれの縦溝２ａ、２ｂ、２ｃ、２ｄと横溝４ａ、４ｃとで区分された各中間ブロック７ａ、７ｃがタイヤ周方向に繰り返し配列されている。なお、この各中間ブロック７ａ、７ｃのさらに両側には、縦溝２ａ、２ｄを挟んでタイヤ周方向に延びるショルダーリブ８ａ、８ｂが設けられている。
【００１９】
また、本実施形態のタイヤは、図１及び図２に示される様に、上記縦溝２ａ、２ｂ、２ｃ、２ｄの各側壁３１、３２、３３、３４、３５、３６、３７、３８から溝幅方向へ突出体Ｔ１、Ｔ２、Ｔ３、Ｔ４、Ｔ５、Ｔ６、Ｔ７、Ｔ８がタイヤ周方向に沿って、不等間隔で設けたタイヤである。縦溝２ａ、２ｂ、２ｃ、２ｄは突出体Ｔを配していない部分の溝幅は、いずれも同一で溝幅はＧＷ、溝深さは突出体の有無に関係なく、同じ深さＤである。突出体Ｔ１、Ｔ２、Ｔ３、Ｔ４、Ｔ５、Ｔ６、Ｔ７、Ｔ８はいずれも同一形状で、縦溝幅方向への突出長さがＧＰ、周方向長さがＧＬ、溝深さ方向長さがＧＤで、ＧＰ＜ＧＤ、ＧＰ＜ＧＬ、縦溝深さＤの１／２点の箇所を含む領域に配されている。従って、突出体間の間隙ＧＳは（ＧＷ−２ＧＰ）である。
【００２０】
図３は図１におけるＡ−Ａ線概略断面図で、同図（ａ）は非接地時、同図（ｂ）は接地時を示す。また、図４は本実施形態のタイヤから前記突出体を除去した場合のトレッドパターンの概略展開図で各符号は図１に同じである。
図５は図４におけるＢ−Ｂ線概略断面図で、同図（ａ）は非接地時、同図（ｂ）は接地時を示す。
【００２１】
図３（ａ）、図３（ｂ）から分かるように、本実施形態の突出体Ｔ３、Ｔ４を配したタイヤの縦溝内では、非接地時は、突出体Ｔ３と突出体Ｔ４との間隙は確保されているが、接地時は前記突出体Ｔ３と突出体Ｔ４同士が完全に接触していてその間隙は無くなっている。但し、本実施形態のタイヤでは前記突出体Ｔ３と突出体Ｔ４が溝底まで配されていないので、溝底側はタイヤ周方向に連続して連なっている。これに対して、本実施形態のタイヤから前記突出体を除去したタイヤの場合、図５（ａ）、図５（ｂ）に示す様に、縦溝内では、非接地時は、縦溝は確保されているが、接地時は縦溝３３、縦溝３４同士が完全に接触していてその間隙は無くなっている。また、本実施形態のタイヤと比較して前記突出体が配されていないので、溝底近くまで縦溝３３、縦溝３４同士が接触していて溝底では殆ど間隙が無くなっている。
【００２２】
なお、図３（ｂ）、図５（ｂ）の点線９はタイヤの非接地時の図３（ａ）、図５（ａ）の縦溝の概略断面を示している。
図３及び図５から縦溝内に、突出体Ｔ３、突出体Ｔ４を配した本実施形態のタイヤは、前記突出体を配さないタイヤに比較して、タイヤ接地時に溝壁の動きが少なく、且つ、溝底での空間が確保されていることが分かる。すなわち、本実施形態の場合、上記突出体を配してもタイヤ走行時に排水性の確保も可能である。
【００２４】
上記の通り、本実施形態のタイヤは、タイヤ周方向に延びる縦溝２ａ、２ｂ、２ｃ、２ｄ内を、基準負荷状態でのタイヤ周方向接地長ｌ３内に、対向する溝壁３の両側または片側の溝壁から溝幅方向へ当該縦溝深さの１／２の位置を含む領域に、１箇所以上配した上記突出体Ｔが、接地の際に縦溝と路面で構成される気柱管内の振動モードを特定の周波数から断続的或いは連続的に変化する周波数とするため、気柱共鳴音は実質的に消滅することができる。
【００２５】
同時に、本実施形態のタイヤは、少なくとも１本の縦溝内において、基準負荷状態でのタイヤ周方向Ｒの接地長Ｌ３内に、対向する溝壁３の両側または片側の溝壁から溝幅方向へ、接地の際にトレッド陸部の縦溝壁の溝幅方向への膨らみ変形の最大となる当該縦溝深さの１／２の位置を含む領域に、１箇所以上の突出体Ｔを配したので、縦溝２に隣接する陸部端は、その部分の動きが抑制される。その結果、該陸部端の路面との間のすべり量が抑制されて偏摩耗いわゆるリバーウェアの発生を防止することができる。
【００２６】
さらに、本実施形態のタイヤは、少なくとも１本の縦溝２内において、基準負荷状態でのタイヤ周方向接地長Ｌ３内に、対向する溝壁の両側または片側の溝壁から溝幅方向へ当該縦溝深さの１／２の位置を含む領域に、１箇所以上配されている前記突出体Ｔがタイヤ接地時に、対向する突出体Ｔ同志または突出体Ｔと溝壁３とが接触する。かかる場合、元来トレッドパターンのピッチ数で決まるポンピング周波数を、負荷接地時に前記突出体Ｔのタイヤ周方向の配置間隔で決まる周波数に転換することができ、かつランダム化することができる。従って、上記ポンピング周波数はトレッドのブロックパターンのピッチ数と車両速度、即ち、タイヤ回転数で決まるトレッドの路面に対する打撃に伴う振動音の周波数のと一致しなくなり、ポンピング音と打撃振動音が強めあうことがなくなり、タイヤの車外騒音に寄与度の大きい上記パターンのピッチ数とタイヤ回転数で決まる１次ピーク周波数のレベルの低減が可能となる。
【００２７】
従って、本発明のタイヤは、縦溝と接地路面間で生じる気柱管共鳴音の低減とポンピング音の低減を図ることができ、車外騒音に対して有効に対処することができると共に、タイヤの偏摩耗防止を図ることができる空気入りタイヤを提供することができる。
【００２８】
【発明の効果】
以上の通り、本発明は、タイヤトレッド面にタイヤ周方向に連なる複数の縦溝を有する空気入りタイヤにおいて、トレッド面にタイヤ周方向に延びる複数の縦溝を有する空気入りタイヤにおいて、
少なくとも１本の縦溝内において、基準負荷状態でのタイヤ周方向接地長内に、対向する溝壁の両側または片側の溝壁から溝幅方向へ当該縦溝深さの１／２の位置を含む領域に、対向する一対の突出体を１箇所以上配し、
上記突出体溝幅方向の突出長さをＧＰ、
同溝深さ方向の長さをＧＤ、
同溝長さ方向の長さをＧＬ、
当該縦溝内で対向する突出体同士の間隙をＧＳ、
当該縦溝幅をＧＷ
としたとき、
ＧＰ＜ＧＤ、ＧＰ＜ＧＬ、０．４×ＧＷ≦ＧＳ≦０．８×ＧＷ
である空気入りタイヤであるため、気柱管共鳴音のみならず、タイヤの車外騒音中、大きな騒音の原因となっているポンピング作用による騒音に対しても効果を発揮することができ、全体としてタイヤの車外騒音の低減を図ることができると共に、タイヤの偏摩耗防止を図ることができる空気入りタイヤを提供することができる。
【図面の簡単な説明】
【図１】本発明に係る空気入りタイヤの一実施形態を示すトレッドパターンの概略展開図である。
【図２】図１におけるＡ−Ａ線の部分断面の概略斜視図である。
【図３】図１におけるＡ−Ａ線概略断面図で、同図（ａ）は非接地時、同図（ｂ）は接地時を示す図である。
【図４】本実施形態のタイヤから前記突出体を除去した場合のトレッドパターンの概略展開図である。
【図５】図４におけるＢ−Ｂ線概略断面図で、同図（ａ）は非接地時、同図（ｂ）は接地時を示す図である。
【符号の説明】
１タイヤトレッド面
２縦溝
２ａ縦溝
２ｂ縦溝
２ｃ縦溝
２ｄ縦溝
３溝壁
３１溝壁
３２溝壁
３３溝壁
３４溝壁
３５溝壁
３６溝壁
３７溝壁
３８溝壁
４ａ横溝
４ｂ横溝
４ｃ横溝
５ショルダー部の接地端
６ショルダー部の接地端
Ｔ突出体
Ｔ１突出体
Ｔ２突出体
Ｔ３突出体
Ｔ４突出体
Ｔ５突出体
Ｔ６突出体
Ｔ７突出体
Ｔ８突出体[0001]
BACKGROUND OF THE INVENTION
The present invention is a pneumatic tire having a plurality of longitudinal grooves extending in the tire circumferential direction on a tread surface, and reduces noise generated during tire travel, and so-called uneven wear that occurs at the end of a land portion adjacent to the longitudinal groove. The present invention relates to a pneumatic tire for improving the tire.
[0002]
[Prior art]
The tire tread portion is likely to generate noise caused by vibration of air flowing in a cavity formed by the road surface and the longitudinal groove of the tire at the tire ground contact portion, that is, noise due to air column resonance during traveling of the vehicle.
[0003]
In addition, since the belt layer of a pneumatic tire with a radial carcass is provided with a highly elastic steel cord, the overall rigidity of the tire tread is high, and the rigidity of the tread with high rigidity is locally low. However, the end of the land adjacent to the vertical groove is easy to move during running of the tire, and the amount of slip between the land and the road surface increases and wear progresses, so that uneven wear, so-called river wear, is likely to occur.
[0004]
Conventionally, various proposals have been made to prevent such noise generation and uneven wear, but no invention has been proposed to improve both.
[0005]
[Problems to be solved by the invention]
An object of the present invention is a pneumatic tire having a plurality of longitudinal grooves extending in the tire circumferential direction on the tread surface, reducing noise generated when the tire is running, and so-called uneven wear occurring at a land portion end adjacent to the longitudinal groove. It aims to improve riverware.
[0006]
By the way, in order to reduce the noise outside the vehicle of the tire, not only the air column resonance noise in the longitudinal groove but also the noise due to the pumping action, which is a large noise factor during the noise outside the vehicle, is effective. This is very important. That is, when the tire contacts the road surface, a vehicle load acts on the tire contact surface. In such a case, both the walls of the land portions located on both sides of the longitudinal groove are compressed by the ground and the longitudinal wall is compressed. It swells inside the groove and approaches to the point where the vertical groove closes. When the ground contact state is released along with the rotation of the tire, the bulge of the land portion returns to its original state due to the absence of load, and the cross-sectional shape of the predetermined vertical groove is restored. The compression to the vertical groove by the land portions on both sides and the release thereof are repeated so that air is sucked and discharged into the vertical groove and presents a so-called pumping state, which is the same as hitting the road surface by the tire pattern It becomes the frequency and overlaps and strengthens, and this becomes the largest contribution to the cause of noise outside the vehicle. In the conventional technology aiming at reducing the air column resonance noise, the effect of suppressing the pumping action is insufficient, and the effect of reducing the noise outside the vehicle as a whole is insufficient.
[0007]
An object of the present invention is to use not only air column resonance noise but also loud noise in the outside of a vehicle, using a protrusion protruding in the groove width direction from a groove wall of a longitudinal groove extending in the tire circumferential direction. It is an object of the present invention to provide a pneumatic tire that is also effective against noise caused by the pumping action and that can reduce the noise outside the tire as a whole and at the same time prevent uneven wear of the tire.
[0008]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present invention provides:
In a pneumatic tire having a plurality of longitudinal grooves extending in the tire circumferential direction on the tread surface,
Comprising at least one longitudinal groove, in the circumferential direction of the tire contact patch in length at the reference load condition, the half of the position of opposing the longitudinal groove depth from both sides of the groove wall of the groove walls to the groove width direction Arrange one or more pairs of opposing protrusions in the area,
The protrusion length in the protrusion groove width direction is GP,
The length in the groove depth direction is GD,
The length in the groove length direction is GL,
The gap between the projecting bodies facing each other in the vertical groove is GS,
The vertical groove width is GW
When
GP <GD, GP <GL, 0.4 × GW ≦ GS ≦ 0.8 × GW
The pneumatic tire which is is adopted.
[0009]
Accordingly, in the tire of the present invention, the depth of the vertical groove from the groove wall on both sides or one side of the opposite groove wall to the groove width direction is within the tire circumferential contact length in the reference load state in at least one vertical groove. One or more of the protrusions arranged in a region including 1/2 of the position of the vibration mode in the air column tube composed of the vertical groove and the road surface at the time of grounding intermittently or continuously from a specific frequency. Since the frequency changes, the air column resonance can be substantially eliminated.
In addition, the said reference | standard load state means the state which gave the air pressure prescribed | regulated to JIS specification and the load corresponding to it for every size of each tire.
Further, in the tire of the present invention, in at least one longitudinal groove, the longitudinal groove depth extends from the groove wall on both sides or one side of the opposing groove wall in the groove width direction within the tire circumferential contact length in the reference load state. Since one or more protrusions are disposed in the region including the position of 1/2 of the height, the movement of the land portion end adjacent to the vertical groove is suppressed. In other words, the vertical rigidity of the block is apparently increased, and as a result, the amount of slip between the block and the road surface at the end of the land portion is suppressed, thereby preventing the occurrence of uneven wear, so-called river wear.
[0010]
Further, in the tire of the present invention, in at least one longitudinal groove, the longitudinal groove depth extends from the groove wall on both sides or one side of the opposing groove wall in the groove width direction within the tire circumferential contact length in the reference load state. When the protrusions arranged at one or more places in the region including the half position are in contact with the tire, the opposing protrusions come into contact with each other . In such a case, the pumping frequency originally determined by the number of pitches of the tread pattern can be converted to a frequency determined by the arrangement interval of the protrusions in the tire circumferential direction at the time of load contact and can be randomized. Therefore, the pumping frequency does not coincide with the pitch number of the tread block pattern, and the pitch of the vibration sound generated by the vibration of the tire when the pattern hitting the road surface for each pitch, which has a large contribution to the outside noise of the tire. The primary peak level determined by the number can be reduced.
[0011]
The projecting length in the groove width direction is GP, the length in the groove depth direction is GD, the length in the groove length direction is GL, and the gap between the projecting bodies facing each other in the vertical groove. GS, when the vertical groove width is GW,
GP <GD, GP <GL, 0.4 × GW ≦ GS ≦ 0.8 × GW
The reason is that if at least one of the conditions of GP <GD or GP <GL is not satisfied, the projecting body is compressed when both the walls of the groove or one of the walls protrudes when the tire is loaded and the groove width is narrowed. This is because the projecting body is buckled, the narrowing of the groove width cannot be sufficiently suppressed, and the pumping action cannot be suppressed.
Further, the reason why the gap GS between the projecting bodies facing each other in the vertical groove is in the range of 0.4 × GW ≦ GS ≦ 0.8 × GW as described above is that the gap GS is less than 0.4 × GW. If the groove volume decreases, the drainage effect in the groove deteriorates, the running stability on the wet road is impaired, and if the gap GS exceeds 0.8 × GW, the narrowing of the groove width by the projecting body is sufficient. This is because it cannot be suppressed and the contribution to suppression of the pumping action is reduced, and as a result, the effect on noise reduction is lost.
[0012]
Moreover, the protrusion body from which the said tire circumferential direction length GL or width | variety GP differs in the same vertical groove can also be arranged. In this case, the rigidity of the protruding body is determined according to the pitch length of the groove walls where the protruding body is installed, that is, the magnitude of the force applied to the protruding body, thereby giving substantially the same apparent rigidity to the entire tread portion. Thus, noise can be suppressed more effectively, and the uniform wear state can be obtained from the uniformity of rigidity with respect to the load on the tread surface portion.
[0013]
It is more preferable that the projecting body is disposed in the tire radial direction on the same surface as the tread ground surface or on the inner side in the tire radial direction with respect to the tread ground surface and on the outer side in the tire radial direction with respect to the groove bottom surface. This is because, if the projecting body is on the outer side in the tire radial direction from the tread contact surface, the tip of the projecting body may be damaged by the external force acting at the time of grounding, or the base of the projecting body may be cracked. The effect of the projecting body is not sufficiently exhibited, and it tends to be a starting point of uneven wear, and the reason that it is located on the outer side in the tire radial direction from the groove bottom surface is to leave a passage for drainage at the bottom of the groove at the time of ground contact.
[0014]
In the same vertical groove,
The circumferential lengths of the adjacent protrusions in the tire circumferential direction are L1, L2,
The interval between the adjacent protrusions is LS,
The length of the tire ground contact circumference in the standard load state is L3
When
L1 ≦ LS <L3, L2 ≦ LS <L3
It is desirable that
[0015]
If the circumferential lengths L1 and L2 of the adjacent protrusions are larger than the interval LS between the adjacent protrusions, fluctuations in the pumping action of the groove suppressed by the protrusions may occur. This is also effective for noise suppression because it is affected and reduced even in the region of the interval LS between the two, but the volume in the groove is narrowed to reduce the water storage and drainage associated therewith. This makes the steering stability on a wet road, which is one of the above, unstable.
Further, when the distance LS between the adjacent protrusions is larger than the tire contact circumferential length L3 in the reference load state, there is a portion in which the protrusion does not intervene in the tire contact circumferential length during traveling. For this reason, air columnar resonance is generated, and generally the pumping action is not suppressed with respect to a pitch including a plurality of lengths in the contact circumferential direction, so that the effect on noise suppression is reduced.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a schematic development view of a tread pattern showing an embodiment of a pneumatic tire according to the present invention. FIG. 2 is a schematic perspective view of a partial cross section taken along line AA in FIG.
[0017]
1 is a tire tread surface, 2 is a longitudinal groove that connects the tire tread surface 1 in the tire circumferential direction R, 3 is a groove wall of the longitudinal groove 2, 4 is a lateral groove, and 5 and 6 are grounding shoulder portions located on both sides of the tire, respectively. End, R is a tire circumferential direction, T is a projecting body, GS is a gap between projecting bodies projecting in the groove width direction from an opposing groove wall, L3 is a tire grounding circumferential length in a reference load state, 10 (dotted line) Is a tire circumferential direction grounding end in a reference load state.
[0018]
In the tire of the present embodiment, as shown in FIG. 1, the vertical groove 2 is composed of one vertical groove 2b, 2c on each side of the tire equator line CL, and further, vertical grooves 2a, 2d on both sides thereof. Has been. And the horizontal groove 4b is provided between the vertical groove 2b and the vertical groove 2c, and the central block 7b divided by this vertical groove 2b, the vertical groove 2c, and the horizontal groove 4b is arranged repeatedly in the tire circumferential direction. . On the other hand, a similar horizontal groove 4a is also provided between the vertical groove 2a and the vertical groove 2b, and a similar horizontal groove 4c is also provided between the vertical groove 2c and the vertical groove 2d. The intermediate blocks 7a and 7c divided by 2c and 2d and the lateral grooves 4a and 4c are repeatedly arranged in the tire circumferential direction. Note that shoulder ribs 8a and 8b extending in the tire circumferential direction are provided on both sides of the intermediate blocks 7a and 7c with the longitudinal grooves 2a and 2d interposed therebetween.
[0019]
Further, as shown in FIGS. 1 and 2, the tire according to the present embodiment has grooves from the side walls 31, 32, 33, 34, 35, 36, 37, and 38 of the longitudinal grooves 2a, 2b, 2c, and 2d. In the tire, protrusions T1, T2, T3, T4, T5, T6, T7, and T8 are provided in the width direction at unequal intervals along the tire circumferential direction. The vertical grooves 2a, 2b, 2c, and 2d have the same groove width in the portion where the protrusion T is not disposed, the groove width is GW, and the groove depth is the same depth D regardless of the presence or absence of the protrusion. is there. The protrusions T1, T2, T3, T4, T5, T6, T7, and T8 have the same shape, the protrusion length in the longitudinal groove width direction is GP, the circumferential length is GL, and the groove depth direction length is In GD, it is arranged in a region including a half point portion of GP <GD, GP <GL, and vertical groove depth D. Therefore, the gap GS between the protrusions is (GW-2GP).
[0020]
3A and 3B are schematic cross-sectional views taken along line AA in FIG. 1. FIG. 3A shows a non-grounded state, and FIG. 3B shows a grounded state. FIG. 4 is a schematic development view of a tread pattern when the protruding body is removed from the tire according to the present embodiment, and each reference numeral is the same as FIG.
5A and 5B are schematic cross-sectional views taken along the line BB in FIG. 4. FIG. 5A shows a non-grounded state, and FIG. 5B shows a grounded state.
[0021]
As can be seen from FIGS. 3A and 3B, in the longitudinal groove of the tire in which the protrusions T3 and T4 of the present embodiment are arranged, the gap between the protrusion T3 and the protrusion T4 when not grounded. However, at the time of grounding, the protrusion T3 and the protrusion T4 are in complete contact with each other, and the gap is eliminated. However, in the tire according to the present embodiment, the protrusion T3 and the protrusion T4 are not arranged to the groove bottom, so that the groove bottom side is continuous in the tire circumferential direction. On the other hand, in the case of the tire from which the protrusion is removed from the tire according to the present embodiment, as shown in FIGS. 5 (a) and 5 (b), the vertical groove is not grounded in the vertical groove. Although it is ensured, the vertical groove 33 and the vertical groove 34 are completely in contact with each other at the time of grounding, and the gap is eliminated. In addition, since the protrusions are not arranged as compared with the tire of the present embodiment, the vertical grooves 33 and the vertical grooves 34 are in contact with each other to the vicinity of the groove bottom, and there is almost no gap at the groove bottom.
[0022]
3 (b) and 5 (b) shows a schematic cross section of the longitudinal groove in FIGS. 3 (a) and 5 (a) when the tire is not grounded.
3 and 5, the tire according to the present embodiment in which the protrusions T3 and T4 are arranged in the vertical groove has less movement of the groove wall at the time of tire contact as compared with the tire without the protrusion. And it turns out that the space in the groove bottom is ensured. That is, in the case of the present embodiment, it is possible to ensure drainability even when the tire is running even if the above-described protrusion is provided.
[0024]
As described above, in the tire according to the present embodiment, the longitudinal grooves 2a, 2b, 2c, and 2d extending in the tire circumferential direction are within the tire circumferential direction ground contact length l3 in the reference load state. An air column in which one or more protrusions T arranged in one or more locations in a region including one half of the longitudinal groove depth in the groove width direction from the groove wall on one side are constituted by the longitudinal groove and the road surface at the time of ground contact Since the vibration mode in the tube is changed to a frequency that changes intermittently or continuously from a specific frequency, the air column resonance can be substantially extinguished.
[0025]
At the same time, in the tire according to the present embodiment, in at least one longitudinal groove, the ground contact length L3 in the tire circumferential direction R in the reference load state is within the groove width direction from the groove walls on both sides or one side of the opposed groove wall 3. In addition, one or more protrusions T are arranged in a region including a position of 1/2 of the vertical groove depth at which the maximum bulge deformation in the groove width direction of the vertical groove wall of the tread land portion occurs at the time of grounding. Therefore, the movement of the portion of the land portion end adjacent to the vertical groove 2 is suppressed. As a result, the amount of slip between the land portion and the road surface is suppressed, and uneven wear, so-called river wear, can be prevented.
[0026]
Further, in the tire according to the present embodiment, in at least one longitudinal groove 2, the tire circumferential direction ground contact length L3 in the reference load state corresponds to the groove width direction from the groove walls on both sides or one side of the opposed groove walls. When the projecting bodies T arranged at one or more places in a region including the position of 1/2 of the longitudinal groove depth are in contact with the tire, the opposing projecting bodies T or the projecting bodies T and the groove wall 3 come into contact with each other. In this case, the pumping frequency originally determined by the number of pitches of the tread pattern can be converted to a frequency determined by the arrangement interval of the protrusions T in the tire circumferential direction at the time of load contact and can be randomized. Therefore, the pumping frequency does not coincide with the frequency of the vibration sound associated with the tread on the road surface determined by the tread block pattern pitch number and the vehicle speed, that is, the tire rotation speed, and the pumping sound and the striking vibration sound strengthen. Therefore, it is possible to reduce the level of the primary peak frequency determined by the number of pitches of the pattern and the number of rotations of the tire that greatly contribute to the noise outside the vehicle.
[0027]
Therefore, the tire of the present invention can reduce the air column resonance noise generated between the longitudinal groove and the ground road surface and the pumping noise, and can effectively cope with the noise outside the vehicle. A pneumatic tire capable of preventing uneven wear can be provided.
[0028]
【Effect of the invention】
As described above, the present invention provides a pneumatic tire having a plurality of longitudinal grooves extending in the tire circumferential direction on the tire tread surface, and a pneumatic tire having a plurality of longitudinal grooves extending in the tire circumferential direction on the tread surface.
In at least one longitudinal groove, within the tire circumferential contact length in the reference load state, a position of ½ of the longitudinal groove depth from the groove wall on both sides or one side of the opposing groove wall in the groove width direction. Arrange one or more pairs of opposing protrusions in the containing area,
The protrusion length in the protrusion groove width direction is GP,
The length in the groove depth direction is GD,
The length in the groove length direction is GL,
The gap between the projecting bodies facing each other in the vertical groove is GS,
The vertical groove width is GW
When
GP <GD, GP <GL, 0.4 × GW ≦ GS ≦ 0.8 × GW
Because it is a pneumatic tire, it can be effective not only for air column resonance noise, but also for noise due to pumping action, which is the cause of loud noise during tire exterior noise, as a whole It is possible to provide a pneumatic tire that can reduce noise outside the vehicle and can prevent uneven wear of the tire.
[Brief description of the drawings]
FIG. 1 is a schematic development view of a tread pattern showing an embodiment of a pneumatic tire according to the present invention.
FIG. 2 is a schematic perspective view of a partial cross section taken along line AA in FIG.
3 is a schematic cross-sectional view taken along the line AA in FIG. 1. FIG. 3 (a) is a diagram showing a non-grounded state, and FIG. 3 (b) is a diagram showing a grounded state.
FIG. 4 is a schematic development view of a tread pattern when the protruding body is removed from the tire according to the embodiment.
5 is a schematic cross-sectional view taken along the line BB in FIG. 4. FIG. 5 (a) is a diagram showing a non-grounded state, and FIG. 5 (b) is a diagram showing a grounded state.
[Explanation of symbols]
1 tire tread surface 2 longitudinal groove 2a longitudinal groove 2b longitudinal groove 2c longitudinal groove 2d longitudinal groove 3 groove wall 31 groove wall 32 groove wall 33 groove wall 34 groove wall 35 groove wall 36 groove wall 37 groove wall 38 groove wall 4a transverse groove 4b transverse groove 4c Horizontal groove 5 Grounding end 6 of the shoulder portion Grounding end T of the shoulder portion Projection T1 Projection T2 Projection T3 Projection T4 Projection T5 Projection T6 Projection T7 Projection T8 Projection

Claims

トレッド面にタイヤ周方向に延びる複数の縦溝を有する空気入りタイヤにおいて、
少なくとも１本の縦溝内において、基準負荷状態でのタイヤ周方向接地長内に、対向する溝壁の両側の溝壁から溝幅方向へ当該縦溝深さの１／２の位置を含む領域に、対向する一対の突出体を１箇所以上配し、
上記突出体溝幅方向の突出長さをＧＰ、
同溝深さ方向の長さをＧＤ、
同溝長さ方向の長さをＧＬ、
当該縦溝内で対向する突出体同士の間隙をＧＳ、
当該縦溝幅をＧＷ
としたとき、
ＧＰ＜ＧＤ、ＧＰ＜ＧＬ、０．４×ＧＷ≦ＧＳ≦０．８×ＧＷ
であることを特徴とする空気入りタイヤ。In a pneumatic tire having a plurality of longitudinal grooves extending in the tire circumferential direction on the tread surface,
Comprising at least one longitudinal groove, in the circumferential direction of the tire contact patch in length at the reference load condition, the half of the position of opposing the longitudinal groove depth from both sides of the groove wall of the groove walls to the groove width direction Arrange one or more pairs of opposing protrusions in the area,
The protrusion length in the protrusion groove width direction is GP,
The length in the groove depth direction is GD,
The length in the groove length direction is GL,
The gap between the projecting bodies facing each other in the vertical groove is GS,
The vertical groove width is GW
When
GP <GD, GP <GL, 0.4 × GW ≦ GS ≦ 0.8 × GW
A pneumatic tire characterized by being.

同一縦溝内において、上記突出体のタイヤ周方向長さが異なる突出体を含む請求項１記載の空気入りタイヤ。The pneumatic tire according to claim 1, comprising protrusions having different lengths in the tire circumferential direction of the protrusions in the same longitudinal groove.

上記突出体のタイヤ径方向の配置領域がトレッド接地表面と同一面乃至トレッド接地表面よりもタイヤ径方向内側で、且つ、溝底面よりもタイヤ径方向外側である請求項１または請求項２記載の空気入りタイヤ。The tire radial direction arrangement region of the projecting body is the same as the tread ground contact surface or the tread ground contact surface and the tire radial direction inner side and the groove bottom surface is the tire radial direction outer side. Pneumatic tire.

同一縦溝内において、
隣り合う上記突出体のタイヤ周方向長さをＬ１、Ｌ２、
隣り合う上記突出体間の間隔をＬＳ、
基準負荷状態でのタイヤ接地周方向長さをＬ３
としたとき、
Ｌ１≦ＬＳ＜Ｌ３、Ｌ２≦ＬＳ＜Ｌ３
である請求項１、請求項２、請求項３の何れかに記載の空気入りタイヤ。In the same vertical groove,
The circumferential lengths of the adjacent protrusions in the tire circumferential direction are L1, L2,
The interval between the adjacent protrusions is LS,
The length of the tire ground contact circumference in the standard load state is L3
When
L1 ≦ LS <L3, L2 ≦ LS <L3
The pneumatic tire according to any one of claims 1, 2, and 3.