JP2005007958A

JP2005007958A - Pneumatic tire

Info

Publication number: JP2005007958A
Application number: JP2003171947A
Authority: JP
Inventors: Katsumichi Sekine; 克理関根; Yukio Tozawa; 幸雄兎沢
Original assignee: Yokohama Rubber Co Ltd
Current assignee: Yokohama Rubber Co Ltd
Priority date: 2003-06-17
Filing date: 2003-06-17
Publication date: 2005-01-13
Anticipated expiration: 2023-06-17
Also published as: JP4281865B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire with improved wet performance. <P>SOLUTION: This pneumatic tire is so configured that a ground surface 13a of a zoned land part 13 formed on a tread surface 1 having a main groove 2 is provided with a through hole 12 extending through the main groove 2 to the side wall surface 13b at the groove bottom side of the main groove 2. The side wall surface opening 12b of the through hole 12 is formed into an opening elongated in the depth direction of the main groove 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、空気入りタイヤに関し、更に詳しくは、ウェット性能を向上するようにした空気入りタイヤに関する。
【０００２】
【従来の技術】
従来、ウェット性能を向上するため、トレッド面に設けたブロックの接地表面に溝底側の側壁面に開口して溝部に連通するようにしたサイプや孔部を排水路として形成した空気入りタイヤが提案されている（例えば、特許文献１参照）。ブロックの接地表面の水分を排水路を介して溝部に排水することで、ブロックの接地性を向上し、それによりウェット性能を高めるようにしている。
【０００３】
【特許文献１】
特開２０００−２４７１１３号公報
【０００４】
【発明が解決しようとする課題】
ところで、近年の車両の高性能化に伴い、より安全性が高いタイヤが求められており、雨天走行時の安全走行を左右するウェット性能についても、一層の改善が求められていた。
【０００５】
本発明は、ウェット性能を向上することが可能な空気入りタイヤを提供することにある。
【０００６】
【課題を解決するための手段】
上記目的を達成する本発明の空気入りタイヤは、トレッド面にタイヤ周方向に延在する主溝を設け、該主溝により陸部を区分形成し、該陸部の接地表面に前記主溝の溝底側の側壁面に開口して該主溝に連通する貫通孔を設けた空気入りタイヤにおいて、前記貫通孔の側壁面開口を前記主溝の深さ方向に長い開口に形成したことを特徴とする。
【０００７】
ウェット路面を走行した際に、接地した陸部の接地表面開口から貫通孔内に流れ込んだ水が側壁面開口から主溝に排水されるが、上記のように貫通孔の側壁面開口を主溝の深さ方向に長い開口に形成して、排水に影響する主溝に対する排水幅（主溝の延在（排水）方向と直交する方向の長さ）を大きくするため、側壁面開口から主溝に排水する効果を高めることができ、その結果、陸部の接地表面における接地性を改善することができるので、ウェット性能の向上が可能になる。
【０００８】
本発明の他の空気入りタイヤは、トレッド面にタイヤ周方向に延在する主溝を設け、該主溝により陸部を区分形成し、該陸部の接地表面に前記主溝の溝底側の側壁面に開口して該主溝に連通する貫通孔を設けた空気入りタイヤにおいて、前記貫通孔の側壁面開口の面積を接地表面開口より広くしたことを特徴とする。
【０００９】
このように貫通孔の側壁面開口を広くすることによっても、側壁面開口から主溝に排水する効果を増大させることができるので、ウェット性能を向上することができる。
【００１０】
本発明の更に他の空気入りタイヤは、トレッド面にタイヤ周方向に延在する主溝を設け、該主溝により陸部を区分形成し、該陸部の接地表面に前記主溝の溝底側の側壁面に開口して該主溝に連通する貫通孔を設けた空気入りタイヤにおいて、前記陸部の接地表面に前記貫通孔に連通するサイプを設けたことを特徴とする。
【００１１】
このようにサイプと貫通孔を組み合わせることによっても、陸部の接地性を改善して、ウェット性能を向上することが可能になる。
【００１２】
本発明の更に他の空気入りタイヤは、トレッド面にタイヤ周方向に延在する主溝を設け、該主溝により陸部を区分形成し、該陸部の接地表面に前記主溝の溝底側の側壁面に開口して該主溝に連通する貫通孔を設けた空気入りタイヤにおいて、前記貫通孔の側壁面開口周囲を凹凸面に形成したことを特徴とする。
【００１３】
このように側壁面開口周囲を凹凸面に形成することで、側壁面開口周囲を流れる主溝内の水を側壁面から剥離させることが可能になるため、側壁面開口から主溝内への排水を促進することができ、その結果、陸部の接地性を改善してウェット性能を向上することができる。
【００１４】
【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ながら詳細に説明する。
【００１５】
図１は本発明の空気入りタイヤの一実施形態を示し、タイヤ回転方向Ｒを一方向に指定したトレッド面１には、タイヤ周方向Ｔに沿って延在する複数（図では４本）の主溝２が設けられている。
【００１６】
タイヤセンターラインＣＬの両側に配置した２本の内側の主溝２Ａ間には、タイヤ周方向Ｔに沿って延在するリブ（陸部）３が区分形成されている。２本の外側の主溝２Ｂよりタイヤ外側には、タイヤ周方向Ｔに沿って延在する細溝４とタイヤ幅方向に延在する横溝５により複数のブロック（陸部）６が区分形成されている。各ブロック６の接地表面には、タイヤ幅方向に延在するサイプ７が設けられている。
【００１７】
主溝２Ａ，２Ｂ間にはタイヤ周方向Ｔに沿って延在する細溝８が形成され、この細溝８と主溝２Ａと間にタイヤ周方向Ｔに沿って延在するリブ（陸部）９が区分形成されている。タイヤ幅方向に延在し、細溝８と主溝２Ｂに連通する横溝１０がタイヤ周方向Ｔに沿って所定のピッチで配置され、これら細溝８、主溝２Ｂ、及び横溝１０により区分形成された複数のブロック（陸部）１１が設けられている。
【００１８】
リブ３，９及びブロック１１の接地表面３ａ，９ａ，１１ａには、隣接する主溝２の溝底側の側壁面３ｂ，９ｂ，１１ｂに開口して主溝２に連通する貫通孔１２が設けられている。これらの貫通孔１２は、図２〜５に示すいずれかの構成、好ましくは、それらを組み合わせた構成を採用するようになっている。なお、図２〜５では、リブ３，９及びブロック１１に相当する陸部を１３、その接地表面を１３ａ、側壁面を１３ｂで示し、図はブロックからなる陸部の例である。
【００１９】
図２は、貫通孔１２の接地表面開口１２ａが円形であるのに対して、側壁面開口１２ｂが主溝２の深さ方向に長い開口に形成した楕円状になっている。接地表面開口１２ａと側壁面開口１２ｂの開口面積は同じである。
【００２０】
ウェット路走行において、接地時に接地表面開口１２ａから貫通孔１２内に流れ込んだ水が側壁面開口１２ｂから主溝２に排出されるが、このように貫通孔１２の側壁面開口１２ｂを主溝２の深さ方向に長い開口に形成することにより、排水に影響する主溝２に対する排水幅（主溝２の延在（排水）方向と直交する方向の長さ）を広くすることができるので、側壁面開口１２ｂから主溝２に排水を促進することができる。そのため、陸部１３の接地性が改善され、ウェット性能を向上することが可能になる。
【００２１】
側壁面開口１２ｂの深さ方向長さａとしては、隣接する主溝２の深さの１５〜７０％にすることができる。深さ方向長さａが主溝２の深さの１５％より短いとウェット性能を改善することが難しくなる。逆に７０％を超えると、陸部の剛性上好ましくない。好ましくは、２０〜３５％にするのがよい。
【００２２】
図３は、貫通孔１２の側壁面開口１２ｂの面積が接地表面開口１２ａのそれより広くしてある。接地表面開口１２ａと側壁面開口１２ｂの形状は、共に円形である。このように貫通孔１２の側壁面開口１２ｂを広くすることによっても、側壁面開口１２ｂから主溝２に対して排水を促進することができるため、陸部１３の接地性が改善され、ウェット性能を向上することができる。
【００２３】
貫通孔１２の接地表面開口１２ａの面積と側壁面開口１２ｂの面積との比としては、１．２〜５の範囲にするのがよい。比が１．２より小さいと、ウェット性能を改善することが難しくなる。逆に５を超えると、陸部の剛性上好ましくない。好ましくは、１．５〜２．２５にするのがよい。
【００２４】
上記のように側壁面開口１２ｂの面積を広くする場合、その面積は陸部の大きさにより適宜選択することができるが、現状の設計条件などでは０．７９〜１７６．７ｍｍ^２、好ましくは、３．１〜２８．３ｍｍ^２の範囲にするのがよい。
【００２５】
図４は、陸部１３の接地表面１３ａに貫通孔１２に連通するサイプ１４を設けたものである。サイプ１４は深さ方向にも貫通孔１２に連通しながら延在し、接地表面開口１２ａと側壁面開口１２ｂの両方に連通している。接地表面開口１２ａと側壁面開口１２ｂの形状は共に円形で、開口面積は同じである。このようにサイプ１４と組み合わせることによっても、陸部１３の接地性を改善して、ウェット性能を向上することができる。
【００２６】
タイヤ幅方向に延在するサイプ１４は、図示するように、貫通孔１２から隣接する主溝２まで連通するように配設するのが好ましいが、主溝１２に連通しないサイプであってもよい。
【００２７】
図５は、陸部１３の側壁面１３ｂにおいて、貫通孔１２の側壁面開口１２ｂ周囲が複数の半球状のディンプル（凹部）１５を形成した凹凸面１６に形成されている。接地表面開口１２ａと側壁面開口１２ｂの形状は共に円形で、開口面積は同じである。
【００２８】
このように側壁面開口１２ｂ周囲を凹凸面１５に形成することで、側壁面開口１２ｂ周囲を流れる主溝２内の水が側壁面１３ｂから剥離し、それにより側壁面開口１２ｂから主溝２内に排水し易くすることができるので、陸部１３の接地性が改善され、ウェット性能の向上が可能になる。
【００２９】
凹凸面１６は、上述したディンプル１５に代えて、半球形状などの凸部を形成することにより凹凸状にしたものであってもよく、またディンプル１５と凸部を組み合わせた形状であってもよい。
【００３０】
凹凸面１６の高さ（ディンプル１５の場合には深さ、凸部の場合には高さ）としては、０．２〜３ｍｍにするのがよい。高さが０．２ｍｍより小さいと、十分な剥離効果を得ることが難しくなる。逆に３ｍｍを超えると、乱流の影響により排水効果が低減する。好ましくは、０．５〜２ｍｍがよい。
【００３１】
図６に示すように、側壁面開口１２ｂの中心Ｏから縁までの距離をｘ（ｍｍ）、側壁面開口１２ｂの縁から側壁面開口１２ｂに最も近い側に並ぶディンプル１５Ａの縁までの距離をｙ（ｍｍ）とすると、距離ｙがｘ≦ｙ≦５ｘ、好ましくは約３ｘとなるようにディンプル１５Ａを側壁面開口１２ｂの周囲に配置するのがよい。距離ｙがｘより小さいと、剥離効果を発揮することが難しくなる。逆に５ｘを超えると、ディンプルとしての効果はあまり変わらず、主溝２内の流れを乱す効果が大きくなる。
【００３２】
隣接するディンプル１５の中心間距離ｚとしては、１〜５ｍｍの範囲にするのがよい。中心間距離ｚが１ｍｍ未満であると、ディンプル１５が集まって実質的に大きなディンプルとなるため、主溝２内の流れを阻害する。逆に５ｍｍを超えると、ディンプルによる剥離効果が低下する。好ましくは、３ｍｍ程度にするのがよい。
【００３３】
ディンプル１５に代えて、凸部を設けた場合も同様である。また、ディンプル１５と凸部の両者を設けた場合には、凹凸面１６の高さは、ディンプル１５の深さと凸部の高さを合計した値、中心間距離ｚは、隣接するディンプル１５間、または隣接する凸部間、または隣接するディンプル１５と凸部間の中心間距離である。
【００３４】
ディンプル１５や凸部の形状は、上述した半球状に限定されず、他の形状であってもよい。
【００３５】
本発明において、貫通孔１２の位置としては、図７に示すように、陸部１３のタイヤ幅方向エッジ１３ｅから陸部幅Ｍの２５％以上陸部１３の内側の領域Ｎに配置するのが陸部剛性の点から好ましい。
【００３６】
貫通孔１２の側壁面開口１２ｂの位置としては、上記のようにタイヤ回転方向Ｒが一方向に指定されている場合には、図８に示すように、接地表面開口１２ａよりタイヤ回転方向後方側に配置するのが側壁面開口１２ｂからの排水促進効果を高める上で好ましいが、図２〜５に示すように、接地表面開口１２ａと同じ位置であってもよい。タイヤ回転方向Ｒが一方向に指定されていない場合には、接地表面開口１２ａと同じ位置に配置する。
【００３７】
陸部１３がリブ３，９の場合には、貫通孔１２の側壁面開口１２ｂを接地表面開口１２ａより隣接する主溝２の溝深さの８０％以上タイヤ回転方向後方側に配置するのが、排水促進効果を高める上よい。上限値としては、１２０％以下にするのがよく、これをを超えると、孔内に水が長く止まり過ぎるようになるため好ましくない。好ましくは、約１００％タイヤ回転方向後方側に配置するのがよい。
【００３８】
陸部１３がブロック１１の場合には、貫通孔１２の接地表面開口１２ａと側壁面開口１２ｂとの差を、ブロック１１のタイヤ周方向長さＬの１０〜４０％の範囲にするのが上記と同様の理由でよい。このように接地表面開口１２ａよりタイヤ回転方向後方側に側壁面開口１２ｂを配置する場合、ブロック剛性の点から、接地表面開口１２ａをブロック１１のタイヤ回転方向側エッジ１１ｆからブロック１１のタイヤ周方向長さＬの２０〜３０％の範囲に、側壁面開口１２ｂをタイヤ回転方向側エッジ１１ｆからタイヤ周方向長さＬの４０〜６０％の範囲に配置するのがよい。
【００３９】
好ましくは、貫通孔１２の接地表面開口１２ａをブロック１１のタイヤ回転方向側エッジ１１ｆからブロック１１のタイヤ周方向長さＬの約２５％の位置、側壁面開口１２ｂをタイヤ回転方向側エッジ１１ｆからタイヤ周方向長さＬの約５０％の位置に配置するのがよい。
【００４０】
貫通孔１２の側壁面開口１２ｂは、その下縁１２ｘ（図８参照）が主溝２の溝底から１．６ｍｍの位置より溝底側となるように側壁面１３ｂに設けるのが、排水効果の点から好ましい。
【００４１】
貫通孔１２の形状は、上述したように接地表面開口１２ａを円形、側壁面開口１２ｂを楕円形や円形にするのがクラックなどの点から好ましいが、それに限定されず、曲線を組み合わせた形状や、矩形状で角部を曲線にした形状などにすることもできる。
【００４２】
【実施例】
タイヤサイズを２０５／６５Ｒ１５、トレッドパターンを図１で共通にし、図２に示す貫通孔を設けた本発明タイヤ１、図３に示す貫通孔を設けた本発明タイヤ２、図４に示す貫通孔を設けた本発明タイヤ３、図５に示す貫通孔を設けた本発明タイヤ４、及び貫通孔の接地表面開口と側壁面開口を共に円形で同じ面積にした従来タイヤをそれぞれ作製した。各貫通孔の接地表面開口と側壁面開口の寸法は、表１に示す通りである。
【００４３】
また、本発明タイヤ１において、接地表面開口の面積と側壁面開口の面積は同じであり、本発明タイヤ４において、凹凸面の高さは０．７ｍｍ、隣接するディンプルの中心間距離は２ｍｍである。
【００４４】
各試験タイヤ共に、貫通孔の接地表面開口を陸部のタイヤ幅方向エッジから陸部幅の５０％の位置に配置し、ブロックの貫通孔は、更に接地表面開口をブロックのタイヤ回転方向側エッジからブロックのタイヤ周方向長さの２５％の位置に配置した。貫通孔の側壁面開口は、８ｍｍ後方にずれており、側壁面開口の下縁は主溝の溝底に位置させている。主溝の深さは８．２ｍｍである。
【００４５】
これら各試験タイヤをリムサイズ１５×６ＪＪのリムに装着し、空気圧を２００ｋＰａにして、排気量２０００ｃｃの車両に取り付け、以下に示す方法により、ウェット性能の評価試験を行ったところ、表１に示す結果を得た。
ウェット性能
平均水深１０ｍｍのウェット路面を走行した際にハイドロプレーニング現象が発生した時の速度を測定し、その結果を従来タイヤを１００とする指数値で評価した。この値が大きいほど、ウェット性能が優れている。
【００４６】
【表１】

表１から、本発明タイヤは、ウェット性能を改善できることがわかる。
【００４７】
【発明の効果】
上述したように本発明は、陸部の接地表面に設けた主溝に連通する貫通孔を上記のように規定することにより、ウェット性能を向上することができる。
【図面の簡単な説明】
【図１】本発明の空気入りタイヤの一実施形態を示すトレッド面の要部展開図である。
【図２】陸部に設けた貫通孔の一例を示す斜視図である。
【図３】陸部に設けた貫通孔の他の例を示す斜視図である。
【図４】陸部に設けた貫通孔の更に他の例を示す斜視図である。
【図５】陸部に設けた貫通孔の更に他の例を示す斜視図である。
【図６】図５の要部拡大図である。
【図７】貫通孔の位置を示す平面説明図である。
【図８】貫通孔の位置を示す側面説明図である。
【符号の説明】
１トレッド面２主溝
３リブ（陸部）３ａ接地表面
３ｂ側壁面９リブ（陸部）
９ａ接地表面９ｂ側壁面
１０横溝１１ブロック（陸部）
１１ａ接地表面１１ｂ側壁面
１１ｆタイヤ回転方向側エッジ１２貫通孔
１２ａ接地表面開口１２ｂ側壁面開口
１３陸部１３ａ接地表面
１３ｂ側壁面１３ｅタイヤ幅方向エッジ
１４サイプ１５ディンプル
１６凹凸面Ｌタイヤ周方向長さ
Ｍ陸部幅Ｒタイヤ回転方向
Ｔタイヤ周方向ａ深さ方向長さ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that improves wet performance.
[0002]
[Prior art]
Conventionally, in order to improve wet performance, there is a pneumatic tire in which sipes and holes that are open to the side wall surface on the groove bottom side and communicate with the groove portion are formed as drainage channels on the ground contact surface of the block provided on the tread surface. It has been proposed (see, for example, Patent Document 1). By draining the water on the ground contact surface of the block to the groove through the drainage channel, the ground contact property of the block is improved, thereby improving the wet performance.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-247113
[Problems to be solved by the invention]
By the way, with higher performance of vehicles in recent years, tires with higher safety have been demanded, and further improvement has been demanded for wet performance that influences safe running during rainy driving.
[0005]
An object of the present invention is to provide a pneumatic tire capable of improving wet performance.
[0006]
[Means for Solving the Problems]
In the pneumatic tire of the present invention that achieves the above object, a main groove extending in the tire circumferential direction is provided on a tread surface, a land portion is sectioned by the main groove, and the main groove is formed on a ground contact surface of the land portion. In the pneumatic tire provided with a through hole that opens to the side wall surface on the groove bottom side and communicates with the main groove, the side wall surface opening of the through hole is formed as an opening that is long in the depth direction of the main groove. And
[0007]
When running on a wet road surface, the water that flows into the through hole from the grounded surface opening of the grounded land is drained from the side wall surface opening to the main groove. In order to increase the drainage width (length in the direction perpendicular to the direction of extension of the main groove (drainage)) to the main groove that affects drainage, the main groove is formed from the side wall surface opening. As a result, it is possible to improve the ground contact property on the ground contact surface of the land portion, so that the wet performance can be improved.
[0008]
In another pneumatic tire of the present invention, a main groove extending in the tire circumferential direction is provided on a tread surface, and a land portion is sectioned by the main groove, and a groove bottom side of the main groove is formed on a ground contact surface of the land portion. In the pneumatic tire provided with a through hole that opens in the side wall surface and communicates with the main groove, the area of the side wall surface opening of the through hole is made larger than the ground contact surface opening.
[0009]
Since the effect of draining from the side wall surface opening to the main groove can be increased also by widening the side wall surface opening of the through hole in this way, the wet performance can be improved.
[0010]
Still another pneumatic tire according to the present invention is provided with a main groove extending in the tire circumferential direction on a tread surface, a land portion is sectioned by the main groove, and a groove bottom of the main groove is formed on a ground contact surface of the land portion. In a pneumatic tire provided with a through hole that opens in the side wall surface on the side and communicates with the main groove, a sipe that communicates with the through hole is provided on the ground contact surface of the land portion.
[0011]
By combining the sipe and the through hole in this way, it is possible to improve the ground contact property of the land portion and improve the wet performance.
[0012]
Still another pneumatic tire according to the present invention is provided with a main groove extending in the tire circumferential direction on a tread surface, a land portion is sectioned by the main groove, and a groove bottom of the main groove is formed on a ground contact surface of the land portion. In the pneumatic tire provided with a through hole that opens to the side wall surface on the side and communicates with the main groove, the periphery of the side wall surface opening of the through hole is formed as an uneven surface.
[0013]
By forming the sidewall surface periphery around the sidewall surface in this manner, the water in the main groove flowing around the sidewall surface opening can be separated from the sidewall surface, so drainage from the sidewall surface opening into the main groove is possible. As a result, it is possible to improve the contact performance of the land and improve the wet performance.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
[0015]
FIG. 1 shows an embodiment of a pneumatic tire according to the present invention. On a tread surface 1 in which the tire rotation direction R is designated as one direction, a plurality of (four in the figure) extending along the tire circumferential direction T are shown. A main groove 2 is provided.
[0016]
Between the two inner main grooves 2A arranged on both sides of the tire center line CL, ribs (land portions) 3 extending along the tire circumferential direction T are formed in sections. A plurality of blocks (land portions) 6 are sectioned by a narrow groove 4 extending along the tire circumferential direction T and a lateral groove 5 extending in the tire width direction on the tire outer side from the two outer main grooves 2B. ing. A sipe 7 extending in the tire width direction is provided on the ground contact surface of each block 6.
[0017]
A narrow groove 8 extending along the tire circumferential direction T is formed between the

main grooves

2A and 2B, and a rib (land portion extending between the narrow groove 8 and the main groove 2A along the tire circumferential direction T is formed. ) 9 is sectioned. The lateral grooves 10 extending in the tire width direction and communicating with the narrow grooves 8 and the main grooves 2B are arranged at a predetermined pitch along the tire circumferential direction T, and are formed by the narrow grooves 8, the main grooves 2B, and the lateral grooves 10 A plurality of blocks (land portions) 11 are provided.
[0018]
On the

grounding surfaces

3 a, 9 a, 11 a of the ribs 3, 9 and the block 11, there are provided through holes 12 that open to the

side wall surfaces

3 b, 9 b, 11 b on the groove bottom side of the adjacent main groove 2 and communicate with the main groove 2. It has been. These through holes 12 adopt any one of the configurations shown in FIGS. 2 to 5, preferably a combination thereof. 2 to 5, the land portions corresponding to the ribs 3 and 9 and the block 11 are indicated by 13, the ground contact surface thereof is indicated by 13 a, and the side wall surface is indicated by 13 b, and the figures are examples of the land portion including blocks.
[0019]
In FIG. 2, the ground surface opening 12 a of the through hole 12 is circular, whereas the side wall surface opening 12 b has an elliptical shape formed in an opening that is long in the depth direction of the main groove 2. The opening area of the ground surface opening 12a and the side wall surface opening 12b is the same.
[0020]
During wet road travel, water that flows into the through hole 12 from the ground contact surface opening 12a at the time of ground contact is discharged from the side wall surface opening 12b to the main groove 2. Thus, the side wall surface opening 12b of the through hole 12 passes through the main groove 2 in this way. By forming an opening that is long in the depth direction, it is possible to widen the drainage width (the length in the direction perpendicular to the extending (drainage) direction of the main groove 2) with respect to the main groove 2 that affects drainage. Drainage can be promoted from the side wall surface opening 12 b to the main groove 2. Therefore, the grounding property of the land portion 13 is improved, and the wet performance can be improved.
[0021]
The length a in the depth direction of the side wall surface opening 12b can be 15 to 70% of the depth of the adjacent main groove 2. If the length a in the depth direction is shorter than 15% of the depth of the main groove 2, it is difficult to improve the wet performance. Conversely, if it exceeds 70%, it is not preferable in terms of rigidity of the land portion. Preferably, the content is 20 to 35%.
[0022]
In FIG. 3, the area of the side wall surface opening 12b of the through hole 12 is larger than that of the ground surface opening 12a. Both the ground surface opening 12a and the side wall opening 12b are circular. Since the drainage can be promoted from the side wall surface opening 12b to the main groove 2 also by widening the side wall surface opening 12b of the through hole 12 in this way, the grounding property of the land portion 13 is improved, and the wet performance Can be improved.
[0023]
The ratio of the area of the ground contact surface opening 12a of the through hole 12 to the area of the side wall surface opening 12b is preferably in the range of 1.2-5. If the ratio is smaller than 1.2, it becomes difficult to improve the wet performance. Conversely, if it exceeds 5, it is not preferable in terms of the rigidity of the land portion. Preferably, it is 1.5 to 2.25.
[0024]
When the area of the side wall surface opening 12b is increased as described above, the area can be appropriately selected depending on the size of the land portion, but in the current design conditions, etc., 0.79 to 176.7 mm ² , it is preferable in the range of 3.1~28.3mm ^2.
[0025]
In FIG. 4, a sipe 14 communicating with the through hole 12 is provided on the ground contact surface 13 a of the land portion 13. The sipe 14 extends in the depth direction while communicating with the through hole 12, and communicates with both the ground surface opening 12a and the side wall surface opening 12b. The ground surface opening 12a and the side wall opening 12b are both circular in shape and have the same opening area. By combining with the sipe 14 as described above, the grounding property of the land portion 13 can be improved and the wet performance can be improved.
[0026]
The sipe 14 extending in the tire width direction is preferably disposed so as to communicate from the through hole 12 to the adjacent main groove 2 as shown in the figure, but may be a sipe that does not communicate with the main groove 12. .
[0027]
In FIG. 5, in the side wall surface 13 b of the land portion 13, the periphery of the side wall surface opening 12 b of the through hole 12 is formed on the uneven surface 16 in which a plurality of hemispherical dimples (concave portions) 15 are formed. The ground surface opening 12a and the side wall opening 12b are both circular in shape and have the same opening area.
[0028]
By forming the periphery of the side wall surface opening 12b in the uneven surface 15 in this way, the water in the main groove 2 flowing around the side wall surface opening 12b is separated from the side wall surface 13b, and thereby the inside of the main groove 2 from the side wall surface opening 12b. Therefore, the grounding property of the land portion 13 is improved, and the wet performance can be improved.
[0029]
The concavo-convex surface 16 may be formed into a concavo-convex shape by forming a convex portion such as a hemisphere instead of the dimple 15 described above, or may be a shape in which the dimple 15 and the convex portion are combined. .
[0030]
The height of the concavo-convex surface 16 (depth in the case of the dimple 15 and height in the case of the convex portion) is preferably 0.2 to 3 mm. If the height is smaller than 0.2 mm, it is difficult to obtain a sufficient peeling effect. Conversely, if it exceeds 3 mm, the drainage effect is reduced due to the influence of turbulent flow. Preferably, 0.5-2 mm is good.
[0031]
As shown in FIG. 6, the distance from the center O of the side wall surface opening 12b to the edge is x (mm), and the distance from the edge of the side wall surface opening 12b to the edge of the dimple 15A arranged closest to the side wall surface opening 12b is Assuming that y (mm), the dimple 15A may be arranged around the side wall surface opening 12b so that the distance y satisfies x ≦ y ≦ 5x, preferably about 3x. If the distance y is smaller than x, it is difficult to exert the peeling effect. Conversely, if it exceeds 5x, the effect as a dimple does not change much, and the effect of disturbing the flow in the main groove 2 becomes large.
[0032]
The center distance z between adjacent dimples 15 is preferably in the range of 1 to 5 mm. If the center-to-center distance z is less than 1 mm, the dimples 15 are gathered to form a substantially large dimple, so that the flow in the main groove 2 is hindered. On the other hand, if it exceeds 5 mm, the peeling effect by dimples decreases. Preferably, the thickness is about 3 mm.
[0033]
The same applies when a convex portion is provided instead of the dimple 15. When both the dimple 15 and the convex portion are provided, the height of the concave-convex surface 16 is the sum of the depth of the dimple 15 and the height of the convex portion, and the center distance z is the distance between adjacent dimples 15. , Or the distance between adjacent convex parts, or the center-to-center distance between adjacent dimples 15 and convex parts.
[0034]
The shape of the dimple 15 and the convex portion is not limited to the above-described hemispherical shape, and may be another shape.
[0035]
In the present invention, as shown in FIG. 7, the positions of the through holes 12 are arranged in the region N inside the land portion 13 by 25% or more of the land width M from the tire width direction edge 13 e of the land portion 13. This is preferable from the viewpoint of land rigidity.
[0036]
When the tire rotation direction R is designated as one direction as described above, the position of the side wall surface opening 12b of the through hole 12 is rearward in the tire rotation direction from the ground contact surface opening 12a as shown in FIG. However, as shown in FIGS. 2 to 5, it may be located at the same position as the ground contact surface opening 12a. When the tire rotation direction R is not designated as one direction, it is arranged at the same position as the ground contact surface opening 12a.
[0037]
When the land portion 13 is the ribs 3 and 9, the side wall surface opening 12 b of the through hole 12 is arranged on the rear side in the tire rotation direction by 80% or more of the groove depth of the main groove 2 adjacent to the ground surface opening 12 a. It is good for enhancing drainage promotion effect. The upper limit is preferably 120% or less, and exceeding this is not preferable because water will remain in the pores for a long time. Preferably, it should be about 100% rearward in the tire rotation direction.
[0038]
When the land portion 13 is the block 11, the difference between the ground contact surface opening 12 a and the side wall surface opening 12 b of the through hole 12 is in the range of 10 to 40% of the tire circumferential direction length L of the block 11. It is good for the same reason. Thus, when the side wall surface opening 12b is arranged behind the ground contact surface opening 12a in the tire rotation direction, from the point of block rigidity, the ground contact surface opening 12a extends from the tire rotation direction side edge 11f of the block 11 to the tire circumferential direction of the block 11. In the range of 20 to 30% of the length L, the side wall surface opening 12b is preferably arranged in the range of 40 to 60% of the tire circumferential direction length L from the tire rotation direction side edge 11f.
[0039]
Preferably, the ground contact surface opening 12a of the through-hole 12 is located at about 25% of the tire circumferential direction length L of the block 11 from the tire rotation direction side edge 11f of the block 11, and the side wall surface opening 12b is from the tire rotation direction side edge 11f. It is good to arrange at about 50% of the tire circumferential direction length L.
[0040]
The side wall surface opening 12b of the through hole 12 is provided on the side wall surface 13b so that the lower edge 12x (see FIG. 8) is 1.6 mm from the groove bottom of the main groove 2 on the groove bottom side. From the point of view, it is preferable.
[0041]
As described above, the shape of the through-hole 12 is preferably that the grounding surface opening 12a is circular and the side wall surface opening 12b is elliptical or circular from the viewpoint of cracks, etc. Also, the shape can be a rectangular shape with curved corners.
[0042]
【Example】
The tire size is 205 / 65R15, the tread pattern is the same as in FIG. 1, the tire 1 of the present invention provided with the through hole shown in FIG. 2, the tire 2 of the invention provided with the through hole shown in FIG. 3, the through hole shown in FIG. The tire 3 of the present invention, the tire 4 of the present invention provided with the through-hole shown in FIG. 5, and the conventional tire in which the ground contact surface opening and the side wall surface opening of the through-hole are both circular and have the same area were prepared. The dimensions of the grounding surface opening and the side wall surface opening of each through hole are as shown in Table 1.
[0043]
In the tire 1 of the present invention, the area of the contact surface opening and the area of the side wall surface opening are the same. In the tire 4 of the present invention, the height of the uneven surface is 0.7 mm, and the distance between the centers of adjacent dimples is 2 mm. is there.
[0044]
In each test tire, the ground contact surface opening of the through hole is arranged at a position that is 50% of the land width in the tire width direction edge of the land portion. To 25% of the tire circumferential length of the block. The side wall surface opening of the through hole is shifted 8 mm rearward, and the lower edge of the side wall surface opening is located at the groove bottom of the main groove. The depth of the main groove is 8.2 mm.
[0045]
Each of these test tires was mounted on a rim having a rim size of 15 × 6 JJ, an air pressure of 200 kPa was attached to a vehicle having a displacement of 2000 cc, and a wet performance evaluation test was performed by the following method. The results shown in Table 1 were obtained. Got.
Wet performance When the hydroplaning phenomenon occurred when running on a wet road surface with an average water depth of 10 mm, the speed was measured, and the result was evaluated with an index value where the conventional tire was 100. The larger this value, the better the wet performance.
[0046]
[Table 1]

Table 1 shows that the tire of the present invention can improve wet performance.
[0047]
【The invention's effect】
As described above, the present invention can improve the wet performance by defining the through hole communicating with the main groove provided on the ground contact surface of the land portion as described above.
[Brief description of the drawings]
FIG. 1 is a development of a main part of a tread surface showing an embodiment of a pneumatic tire of the present invention.
FIG. 2 is a perspective view showing an example of a through hole provided in a land portion.
FIG. 3 is a perspective view showing another example of a through hole provided in a land portion.
FIG. 4 is a perspective view showing still another example of a through hole provided in a land portion.
FIG. 5 is a perspective view showing still another example of a through hole provided in a land portion.
6 is an enlarged view of a main part of FIG.
FIG. 7 is an explanatory plan view showing the positions of through holes.
FIG. 8 is an explanatory side view showing the positions of through holes.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tread surface 2 Main groove 3 Rib (land part) 3a Grounding surface 3b Side wall surface 9 Rib (land part)
9a Grounding surface 9b Side wall surface 10 Horizontal groove 11 Block (Land part)
11a Ground surface 11b Side wall surface 11f Tire rotation direction side edge 12 Through hole 12a Ground surface opening 12b Side wall surface opening 13 Land portion 13a Ground surface 13b Side wall surface 13e Tire width direction edge 14 Sipe 15 Dimple 16 Concavity and convexity L Tire circumferential length M Land width R Tire rotation direction T Tire circumferential direction a Depth direction length

Claims

A main groove extending in the tire circumferential direction is provided on the tread surface, a land portion is sectioned by the main groove, and the main groove is opened on a side wall surface on the groove bottom side of the main groove on the ground contact surface of the land portion. A pneumatic tire provided with a through hole communicating with the pneumatic tire, wherein the side wall surface opening of the through hole is formed as an opening that is long in the depth direction of the main groove.

The pneumatic tire according to claim 1, wherein a length in a depth direction of the side wall surface opening of the through hole is set to 15 to 70% of a depth of the main groove.

The pneumatic tire according to claim 1 or 2, wherein an area of the side wall surface opening of the through hole is equal to or larger than an area of the ground contact surface opening.

The pneumatic tire according to claim 1, 2 or 3, wherein a sipe communicating with the through hole is provided on a ground contact surface of the land portion.

The pneumatic tire according to claim 1, 2, 3, or 4, wherein the periphery of the opening of the side wall surface of the through hole is formed as an uneven surface.

A main groove extending in the tire circumferential direction is provided on the tread surface, a land portion is sectioned by the main groove, and the main groove is opened on a side wall surface on the groove bottom side of the main groove on the ground contact surface of the land portion. A pneumatic tire provided with a through hole communicating with the pneumatic tire, wherein the area of the side wall surface opening of the through hole is larger than that of the ground contact surface opening.

The pneumatic tire according to claim 6, wherein a ratio of an area of the ground contact surface opening of the through hole to an area of the side wall surface opening is set to 1.2 to 5.

The pneumatic tire according to claim 6 or 7, wherein a sipe communicating with the through hole is provided on a ground contact surface of the land portion.

The pneumatic tire according to claim 6, 7 or 8, wherein the through hole has a concavo-convex surface around the side wall surface opening.

A main groove extending in the tire circumferential direction is provided on the tread surface, a land portion is sectioned by the main groove, and the main groove is opened on a side wall surface on the groove bottom side of the main groove on the ground contact surface of the land portion. A pneumatic tire provided with a through hole that communicates with a through hole, wherein a sipe that communicates with the through hole is provided on a ground contact surface of the land portion.

The pneumatic tire according to claim 10, wherein the sipe communicates with the main groove.

The pneumatic tire according to claim 10 or 11, wherein the periphery of the opening of the side wall surface of the through hole is formed as an uneven surface.

A main groove extending in the tire circumferential direction is provided on the tread surface, a land portion is sectioned by the main groove, and the main groove is opened on a side wall surface on the groove bottom side of the main groove on the ground contact surface of the land portion. A pneumatic tire provided with a through hole communicating with the pneumatic tire, wherein the periphery of the opening of the side wall surface of the through hole is formed as an uneven surface.

The pneumatic tire according to claim 13, wherein a height of the uneven surface is 0.2 to 3 mm.

The pneumatic tire according to any one of claims 1 to 14, wherein the through hole is disposed on the ground contact surface of the land portion at an inner side of the land portion by 25% or more of the land width from an edge in the tire width direction of the land portion.

The air according to any one of 1 to 15, wherein the tread surface is a tread surface in which a tire rotation direction is specified as one direction, and a side wall surface opening of the through hole is arranged on the rear side in the tire rotation direction from the ground surface opening. Tires.

The land portion has a rib extending in the tire circumferential direction, and the side wall surface opening of the through hole provided in the ground contact surface of the rib is rotated by 80 to 120% of the groove depth of the main groove from the ground contact surface opening. The pneumatic tire according to claim 16, which is disposed on the rear side in the direction.

The through hole provided in the ground contact surface of the block, the lateral groove extending in the tire width direction on the tread surface is arranged at a predetermined pitch in the tire circumferential direction, and the land portion has a block divided by the lateral groove. The contact surface opening of the block is in the range of 20 to 30% of the tire circumferential direction length of the block from the tire rotation direction side edge of the block, and the side wall surface opening is from the tire rotation direction side edge of the block of the block to the tire circumferential direction of the block. The pneumatic tire according to claim 16, which is disposed in a range of 40 to 60% of a directional length.