JP3702958B2 - Pneumatic tire for icy and snowy roads - Google Patents

Pneumatic tire for icy and snowy roads Download PDF

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JP3702958B2
JP3702958B2 JP2002197618A JP2002197618A JP3702958B2 JP 3702958 B2 JP3702958 B2 JP 3702958B2 JP 2002197618 A JP2002197618 A JP 2002197618A JP 2002197618 A JP2002197618 A JP 2002197618A JP 3702958 B2 JP3702958 B2 JP 3702958B2
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grooves
narrow groove
narrow
tire
braking
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JP2004034903A (en
JP2004034903A5 (en
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佳昌 橋本
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Yokohama Rubber Co Ltd
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Yokohama Rubber Co Ltd
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Application filed by Yokohama Rubber Co Ltd filed Critical Yokohama Rubber Co Ltd
Priority to DE60329843T priority patent/DE60329843D1/en
Priority to EP03733570A priority patent/EP1520733B1/en
Priority to CA2491957A priority patent/CA2491957C/en
Priority to EP08165096A priority patent/EP2014486A2/en
Priority to AT03733570T priority patent/ATE446859T1/en
Priority to PCT/JP2003/008017 priority patent/WO2004005051A1/en
Priority to US10/513,223 priority patent/US7438100B2/en
Publication of JP2004034903A publication Critical patent/JP2004034903A/en
Publication of JP2004034903A5 publication Critical patent/JP2004034903A5/ja
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/03—Tread patterns
    • B60C11/13—Tread patterns characterised by the groove cross-section, e.g. for buttressing or preventing stone-trapping
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/03—Tread patterns
    • B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
    • B60C11/1204—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe
    • B60C2011/1231—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe being shallow, i.e. sipe depth of less than 3 mm

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Tires In General (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、氷雪路用として好適な空気入りタイヤに関し、さらに詳しくは、トレッド表面に細溝を形成することで、摩耗初期における氷路での制駆動性能を向上すると共に、その細溝を早期に磨滅させることで、トレッドゴム本来の特性を早期に発揮するようにした氷雪路用空気入りタイヤに関する。
【０００２】
【従来の技術】
スタッドレスタイヤに代表される氷雪路用空気入りタイヤでは、例えば、トレッドゴムに充填剤や気泡を混入することにより、トレッド表面に微細な凹凸が形成されるようになっている。これら凹凸は氷路での水膜除去効果を発揮し、氷路での走行性能の向上に寄与する。ところが、慣らし走行前のタイヤではトレッド表面に上記凹凸が十分に現れていないので、摩耗初期において本来の走行性能を十分に発揮することができないという不都合があった。
【０００３】
このような不都合を解決するための技術として、例えば、特開平７−１８６６３３号公報には、トレッド部に区画された陸部のトレッド表面に、タイヤ周方向に延びる微細リブを設けることが提案されている。また、特許第３０１７６７７号公報には、ブロックのトレッド表面に、主サイピングより浅い深さを有し、タイヤ幅方向に延びる補助サイピングを設けることが提案されている。
【０００４】
しかしながら、前者のように微細リブをタイヤ周方向に配向させた場合、微細リブのエッジが制駆動に寄与せず、また微細リブが磨滅してトレッドゴム本来の特性を発揮するまでに多大な時間を要するという問題があった。一方、後者のように補助サイピングをタイヤ幅方向に配向させた場合、補助サイピングが進行方向に延びていないため、氷路での水膜除去効果が不足し、かつトレッド表面に付着した雪が離脱し難いので、摩耗初期における氷路での制駆動性能を十分に向上することができないという問題があった。
【０００５】
特に、近年ではアンチロックブレーキシステム（ＡＢＳ）が自動車の制動装置の主流になっており、そのＡＢＳ制動ではトレッド表面に付着した雪に起因して制動距離が長くなる傾向がある。つまり、ロック制動ではタイヤが同一の接地面で滑るためトレッド表面に付着した雪が摩擦熱で融解するが、ＡＢＳ制動では制動中もタイヤが回転するためトレッド表面に付着した雪が融解し難いのである。そのため、ＡＢＳ制動において、タイヤのトレッド表面に雪が付着していると、本来の制動性能が得られないままブレーキがリリースされてしまい、その繰り返しで制動距離が延びることになる。
【０００６】
【発明が解決しようとする課題】
本発明の目的は、トレッド表面に細溝を形成することで、摩耗初期における氷路での制駆動性能を向上すると共に、その細溝を早期に磨滅させることで、トレッドゴム本来の特性を早期に発揮することを可能にした氷雪路用空気入りタイヤを提供することにある。
【０００７】
【課題を解決するための手段】
上記目的を解決するための本発明の氷雪路用空気入りタイヤは、トレッド部にタイヤ周方向に延びる複数本の主溝とタイヤ幅方向に延びる複数本の横溝とを設け、これら主溝及び横溝によって複数のブロックからなる陸部を区画したブロックパターンを有し、前記陸部に平面視でジグザグ形状をなしてタイヤ幅方向に延長する複数本のサイプを設けた氷雪路用空気入りタイヤにおいて、前記陸部のトレッド表面に前記サイプより浅い複数本の細溝を形成し、これら細溝のタイヤ周方向に対する角度を４２〜６０°とし、前記細溝の深さを０．１〜０．８ｍｍとし、前記細溝の幅を０．１〜０．８ｍｍとし、前記細溝のピッチを０．５〜２．０ｍｍとしたことを特徴とするものである。
【０００８】
このように陸部のトレッド表面にサイプより浅い複数本の細溝を形成し、これら細溝のタイヤ周方向に対する角度を４２〜６０°にしたことにより、氷路面とトレッド表面との間に発生する水膜の除去効果とトレッド表面に付着した雪の排除能力とを低下させることなく、制駆動時に細溝のエッジ効果を十分に得ることができるので、摩耗初期における氷路での制駆動性能を大幅に向上することができる。しかも、制駆動時及びコーナリング時において陸部が受ける摩擦力に基づいて細溝が早期に磨滅するので、トレッドゴム本来の特性を早期に発揮することが可能になる。
【０００９】
本発明では、上記作用効果を十分に得るために、細溝の深さを０．１〜０．８ｍｍとし、細溝の幅を０．１〜０．８ｍｍとし、細溝のピッチを０．５〜２．０ｍｍとすることが好ましい。特に、トレッド表面に付着した雪の排除能力を高めるために、細溝の縁部を湾曲形状にしたり、或いは、細溝の開口部での幅を底部での幅より大きくすることが好ましい。
【００１０】
【発明の実施の形態】
以下、本発明について添付の図面を参照して詳細に説明する。
【００１１】
図１は本発明の実施形態からなる氷雪路用空気入りタイヤのトレッドパターンを示し、図２はそのブロックを拡大して示し、図３はそのブロックに形成された細溝を拡大して示すものである。
【００１２】
図１に示すように、トレッド部１には、タイヤ周方向に延びる複数本の主溝２と、タイヤ幅方向に延びる複数本の横溝３とが設けられている。これら主溝２及び横溝３によって複数のブロック４からなる陸部が区画されている。ブロック４には複数本のサイプ５が形成されている。なお、トレッド部１を構成するゴム組成物には充填剤や気泡が混入され、トレッド表面が摩耗した際に、水膜除去効果を有する微細な凹凸が現れるようになっている。
【００１３】
図２に示すように、ブロック４のトレッド表面には、サイプ５より浅い複数本の細溝６が形成されている。これら細溝６のタイヤ周方向に対する角度θは４２〜６０°の範囲に設定されている。図３において、細溝６の深さＤは０．１〜０．８ｍｍであり、細溝６の幅Ｗは０．１〜０．８ｍｍであり、細溝６のピッチＰは０．５〜２．０ｍｍであることが望ましい。
【００１４】
上述した氷雪路用空気入りタイヤでは、走行時に氷路面とトレッド表面との間に発生する水膜が細溝６によって効果的に除去され、トレッド表面に付着した雪はタイヤ回転時の遠心力によって効果的に排除される。しかも、制駆動時には細溝６のエッジ効果を十分に発揮することが可能である。そのため、細溝６が磨滅するまでの摩耗初期において、氷路での優れた制駆動性能を発揮することができる。
【００１５】
ここで、細溝６のタイヤ周方向に対する角度θが４２°未満であると、細溝６のエッジが制駆動に寄与せず、また細溝６が磨滅してトレッドゴム本来の特性を発揮するまでに多大な時間を要することになる。一方、細溝６のタイヤ周方向に対する角度θが６０°を超えると、氷路での水膜除去効果が不十分になり、またトレッド表面に付着した雪が離脱し難くなる。
【００１６】
細溝６の深さＤが０．１ｍｍ未満であると、氷路での水膜除去効果が不十分になる。また、トレッドゴム本来の特性はトレッド表面が少なくとも０．１ｍｍ以上摩耗した後であるので、その状態まで細溝６を残存させることが要求される。一方、細溝６の深さＤが０．８ｍｍを超えると、水膜除去効果及び排雪能力が増加するが、トレッド剛性が低下するため、氷路での制駆動性能が低下する。
【００１７】
細溝６の幅Ｗが０．１ｍｍ未満であると、水膜除去効果及び排雪能力が不十分になる。一方、細溝６の幅Ｗが０．８ｍｍを超えると、水膜除去効果及び排雪能力は良好であるが、路面との接触面積が減り過ぎるため、氷路での制駆動性能が低下する。
【００１８】
細溝６のピッチＰが０．５ｍｍ未満であると、細溝６の磨滅を促進できるが、トレッド剛性の不足により制駆動時に細溝６が潰れて水膜除去効果及び排雪能力が不十分になる。一方、細溝６のピッチＰが２．０ｍｍを超えると、細溝６の磨滅が遅くなり、しかも細溝６の面積が減少することで水膜除去効果及び排雪能力が不十分になる。
【００１９】
細溝６の平面視形状は、特に限定されるものではなく、図２のような直線状とする以外に、図４のようにジグザグ状にしたり、或いは、波状にすることが可能である。但し、ジグザグ状又は波状の細溝では、その振幅の中心線に基づいてタイヤ周方向に対する角度を特定するものとする。
【００２０】
細溝６の断面形状は、特に限定されるものではなく、図３のような矩形以外でも良い。図５に示すように、細溝６の縁部を曲率半径Ｒの湾曲形状にした場合、排雪能力を高めることができる。また、図６に示すように、細溝６の開口部での幅Ｗ1 を底部での幅Ｗ2 より大きくした場合にも、排雪能力を高めることができる。
【００２１】
なお、細溝６が縦断面において明確なエッジを持たない場合、その開口部での幅Ｗ1 は溝側壁の延長線とトレッド表面の延長線との交点を基準として測定され、その底部での幅Ｗ2 は溝側壁の延長線と溝底面の延長線との交点を基準として測定されるものとする。
【００２２】
上記実施形態ではブロックパターンを有する氷雪路用空気入りタイヤについて説明したが、本発明ではトレッド部に区画される陸部としてタイヤ周方向に延在するリブを設けた場合にも適用することができる。
【００２３】
【実施例】
タイヤサイズ１９５／６５Ｒ１５のブロックパターンを有する氷雪路用空気入りタイヤにおいて、ブロックのトレッド表面にサイプより浅い複数本の細溝を形成し、これら細溝のタイヤ周方向に対する角度θ、平面視形状、細溝幅Ｗ、細溝ピッチＰ、細溝深さＤを表１のように設定した従来例、比較例１〜２及び実施例１〜４をそれぞれ製作した。
【００２４】
これら試験タイヤについて、下記の試験方法により、氷上制動性能及び初期摩耗性を評価し、その結果を表１に併せて示した。
【００２５】
氷上制動性能：
試験タイヤをリムサイズ１５×６．５ＪＪ、空気圧２００ｋＰａとしてアンチロックブレーキシステム（ＡＢＳ）を備えた排気量２５００ｃｃの後輪駆動車に取り付け、氷上にて速度４０ｋｍ／ｈの走行状態からＡＢＳ制動を実施し、その制動距離を測定した。評価結果は、測定値の逆数は用い、従来例を１００とする指数にて示した。この指数値が大きいほど制動距離が短いことを意味する。
【００２６】
初期摩耗性：
試験タイヤをリムサイズ１５×６．５ＪＪ、空気圧２００ｋＰａとして車両に取り付け、一般路を模したテストコースにおいて、平均速度３５ｋｍ／ｈにて走行し、１００ｋｍ毎に細溝の残存量を測定し、その細溝が磨滅するまでの走行距離を測定した。評価結果は、測定値の逆数は用い、従来例を１００とする指数にて示した。この指数値が大きいほど細溝の磨滅が早いことを意味する。
【００２７】
【表１】

Figure 0003702958
表１から判るように、実施例１〜４はいずれも従来例に比べて氷上制動性能が優れており、しかも細溝の磨滅が早いためトレッドゴム本来の特性を早期に発揮できるものであった。一方、比較例１〜２は氷上制動性能の改善効果が不十分であった。
【００２８】
次に、タイヤサイズ１９５／６５Ｒ１５のブロックパターンを有する氷雪路用空気入りタイヤにおいて、ブロックのトレッド表面にサイプより浅い複数本の細溝を形成し、これら細溝のタイヤ周方向に対する角度θを４５°とし、細溝幅Ｗを０．３ｍｍとし、細溝ピッチＰを１．０ｍｍとし、細溝深さＤだけを変化させつつ、上述の試験方法により氷上制動性能を評価し、その結果を図７に示した。但し、評価結果はＤ＝０．３ｍｍの場合を１００とする指数にて示した。図７より、細溝深さＤが０．１〜０．８ｍｍの範囲にあるとき良好な氷上制動性能が得られることが判る。
【００２９】
次に、タイヤサイズ１９５／６５Ｒ１５のブロックパターンを有する氷雪路用空気入りタイヤにおいて、ブロックのトレッド表面にサイプより浅い複数本の細溝を形成し、これら細溝のタイヤ周方向に対する角度θを４５°とし、細溝深さＤを０．３ｍｍとし、細溝ピッチＰを１．０ｍｍとし、細溝幅Ｗだけを変化させつつ、上述の試験方法により氷上制動性能を評価し、その結果を図８に示した。但し、評価結果はＷ＝０．５ｍｍの場合を１００とする指数にて示した。図８より、細溝幅Ｗが０．１〜０．８ｍｍの範囲にあるとき良好な氷上制動性能が得られることが判る。
【００３０】
次に、タイヤサイズ１９５／６５Ｒ１５のブロックパターンを有する氷雪路用空気入りタイヤにおいて、ブロックのトレッド表面にサイプより浅い複数本の細溝を形成し、これら細溝のタイヤ周方向に対する角度θを４５°とし、細溝深さＤを０．３ｍｍとし、細溝幅Ｗを０．３ｍｍとし、細溝ピッチＰだけを変化させつつ、上述の試験方法により氷上制動性能を評価し、その結果を図９に示した。但し、評価結果はＰ＝１．０ｍｍの場合を１００とする指数にて示した。図９より、細溝ピッチＰが０．５〜２．０ｍｍの範囲にあるとき良好な氷上制動性能が得られることが判る。
【００３１】
【発明の効果】
以上説明したように本発明によれば、トレッド部にブロック又はリブからなる複数の陸部を区画し、これら陸部に複数本のサイプを設けた氷雪路用空気入りタイヤにおいて、陸部のトレッド表面にサイプより浅い複数本の細溝を形成し、これら細溝のタイヤ周方向に対する角度を４２〜６０°としたから、その細溝に基づいて摩耗初期における氷路での制駆動性能を向上することができ、しかも細溝を早期に磨滅させることで、トレッドゴム本来の特性を早期に発揮することができる。従って、本発明の氷雪路用空気入りタイヤは、アンチロックブレーキシステムを備えた自動車においても、氷路での優れた制駆動性能を発揮することが可能である。
【図面の簡単な説明】
【図１】本発明の実施形態からなる氷雪路用空気入りタイヤのトレッドパターンを示す展開図である。
【図２】図１のトレッドパターンにおけるブロックを拡大して示す平面図である。
【図３】図２のブロックに形成された細溝を示すブロックの断面図である。
【図４】ジグザグ状の細溝を有するブロックを拡大して示す平面図である。
【図５】面取り加工した細溝を示すブロックの断面図である。
【図６】開口部の幅を大きくした細溝を示すブロックの断面図である。
【図７】細溝深さＤと氷上制動性能との関係を示すグラフである。
【図８】細溝幅Ｗと氷上制動性能との関係を示すグラフである。
【図９】細溝ピッチＰと氷上制動性能との関係を示すグラフである。
【符号の説明】
１ トレッド部
２ 主溝
３ 横溝
４ ブロック
５ サイプ
６ 細溝
Ｄ 細溝の深さ
Ｗ 細溝の幅
Ｐ 細溝のピッチ
θ 細溝の角度[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire suitable for use on icy and snowy roads. More specifically, by forming a narrow groove on the tread surface, the braking / driving performance on the icy road in the early stage of wear is improved, and the narrow groove is quickly removed. The present invention relates to a pneumatic tire for icy and snowy roads, which is made to exhibit the original characteristics of tread rubber at an early stage by being worn out.
[0002]
[Prior art]
In a pneumatic tire for icy and snowy roads typified by studless tires, fine irregularities are formed on the tread surface by, for example, mixing a filler or air bubbles into the tread rubber. These irregularities exhibit the effect of removing the water film on the icy road and contribute to the improvement of the running performance on the icy road. However, in the tire before running-in, the above unevenness does not appear sufficiently on the tread surface, so that the original running performance cannot be sufficiently exhibited in the early stage of wear.
[0003]
As a technique for solving such inconvenience, for example, Japanese Patent Laid-Open No. 7-186633 proposes to provide fine ribs extending in the tire circumferential direction on the tread surface of the land portion partitioned by the tread portion. ing. Japanese Patent No. 3017677 proposes providing auxiliary siping having a shallower depth than the main siping and extending in the tire width direction on the tread surface of the block.
[0004]
However, when the fine ribs are oriented in the tire circumferential direction as in the former case, the edges of the fine ribs do not contribute to braking / driving, and it takes a great amount of time for the fine ribs to wear out and exhibit the original characteristics of the tread rubber. There was a problem of requiring. On the other hand, when the auxiliary siping is oriented in the tire width direction as in the latter case, the auxiliary siping does not extend in the traveling direction, so the water film removal effect on the icy road is insufficient, and the snow attached to the tread surface is detached. Since it is difficult, the braking / driving performance on the icy road at the early stage of wear cannot be sufficiently improved.
[0005]
In particular, in recent years, anti- lock braking systems (ABS) have become the mainstream of automobile braking devices, and in the ABS braking, the braking distance tends to be long due to snow attached to the tread surface. In other words, in the case of rock braking, the tires slide on the same contact surface, so that the snow attached to the tread surface is melted by frictional heat, but in ABS braking, the tire rotates while braking and the snow attached to the tread surface is difficult to melt. Therefore, in ABS braking, if snow adheres to the tread surface of the tire, the brake is released without obtaining the original braking performance, and the braking distance is extended by repeating the braking.
[0006]
[Problems to be solved by the invention]
The object of the present invention is to improve the braking / driving performance on the icy road at the early stage of wear by forming narrow grooves on the tread surface, and at the same time to quickly wear out the original characteristics of the tread rubber by rubbing the narrow grooves at an early stage. An object of the present invention is to provide a pneumatic tire for icy and snowy roads that can be applied to the above.
[0007]
[Means for Solving the Problems]
In order to solve the above object, a pneumatic tire for snowy and snowy road according to the present invention is provided with a plurality of main grooves extending in the tire circumferential direction and a plurality of horizontal grooves extending in the tire width direction in the tread portion. In a pneumatic tire for snowy and snowy roads having a block pattern that divides a land portion composed of a plurality of blocks, and provided with a plurality of sipes extending in the tire width direction in a zigzag shape in plan view on the land portion , A plurality of narrow grooves shallower than the sipe are formed on the tread surface of the land portion, the angle of the narrow grooves with respect to the tire circumferential direction is 42 to 60 °, and the depth of the narrow grooves is 0.1 to 0.8 mm. The width of the narrow groove is 0.1 to 0.8 mm, and the pitch of the narrow groove is 0.5 to 2.0 mm .
[0008]
In this way, a plurality of narrow grooves shallower than the sipe are formed on the tread surface of the land, and the angle of the narrow grooves with respect to the tire circumferential direction is set to 42 to 60 °, thereby generating between the ice road surface and the tread surface. It is possible to obtain the edge effect of the narrow groove at the time of braking / driving without deteriorating the removal effect of the water film to be removed and the ability to remove snow attached to the tread surface. Can be greatly improved. In addition, the narrow groove is quickly worn out based on the frictional force that the land portion receives during braking and cornering, so that the original characteristics of the tread rubber can be exhibited early.
[0009]
In the present invention, in order to sufficiently obtain the above-described effects, the depth of the narrow groove is set to 0.1 to 0.8 mm, the width of the narrow groove is set to 0.1 to 0.8 mm, and the pitch of the narrow grooves is set to 0.1 mm. It is preferable to set it as 5-2.0 mm. In particular, in order to enhance the ability to remove snow attached to the tread surface, it is preferable that the edge of the narrow groove is curved, or the width at the opening of the narrow groove is larger than the width at the bottom.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
[0011]
FIG. 1 shows a tread pattern of a pneumatic tire for an icy and snowy road according to an embodiment of the present invention, FIG. 2 shows an enlarged block, and FIG. 3 shows an enlarged narrow groove formed in the block. It is.
[0012]
As shown in FIG. 1, the tread portion 1 is provided with a plurality of main grooves 2 extending in the tire circumferential direction and a plurality of lateral grooves 3 extending in the tire width direction. The main groove 2 and the lateral groove 3 define a land portion composed of a plurality of blocks 4. A plurality of sipes 5 are formed in the block 4. The rubber composition constituting the tread portion 1 is mixed with fillers and bubbles, and when the tread surface is worn, fine irregularities having a water film removing effect appear.
[0013]
As shown in FIG. 2, a plurality of narrow grooves 6 shallower than the sipe 5 are formed on the tread surface of the block 4. An angle θ of these narrow grooves 6 with respect to the tire circumferential direction is set in a range of 42 to 60 °. In FIG. 3, the depth D of the narrow groove 6 is 0.1 to 0.8 mm, the width W of the narrow groove 6 is 0.1 to 0.8 mm, and the pitch P of the narrow groove 6 is 0.5 to It is desirable to be 2.0 mm.
[0014]
In the pneumatic tire for an icy and snowy road described above, a water film generated between the icy road surface and the tread surface during running is effectively removed by the narrow groove 6, and the snow adhering to the tread surface is caused by the centrifugal force at the time of tire rotation. Effectively eliminated. Moreover, the edge effect of the narrow groove 6 can be sufficiently exhibited during braking / driving. Therefore, excellent braking / driving performance on an icy road can be exhibited in the early stage of wear until the narrow groove 6 is worn out.
[0015]
Here, when the angle θ of the narrow groove 6 with respect to the tire circumferential direction is less than 42 °, the edge of the narrow groove 6 does not contribute to braking / driving, and the narrow groove 6 is worn away to exhibit the original characteristics of the tread rubber. Takes a long time to complete. On the other hand, if the angle θ of the narrow groove 6 with respect to the tire circumferential direction exceeds 60 °, the effect of removing the water film on the icy road becomes insufficient, and the snow attached to the tread surface is difficult to separate.
[0016]
When the depth D of the narrow groove 6 is less than 0.1 mm, the effect of removing the water film on the icy road becomes insufficient. In addition, since the inherent characteristic of the tread rubber is after the tread surface has been worn by at least 0.1 mm or more, it is required to leave the narrow groove 6 until that state. On the other hand, when the depth D of the narrow groove 6 exceeds 0.8 mm, the water film removing effect and the snow discharging ability are increased, but the tread rigidity is lowered, so that the braking / driving performance on the icy road is lowered.
[0017]
When the width W of the narrow groove 6 is less than 0.1 mm, the water film removing effect and the snow discharging ability are insufficient. On the other hand, when the width W of the narrow groove 6 exceeds 0.8 mm, the water film removing effect and the snow draining ability are good, but the contact area with the road surface is reduced too much, so the braking / driving performance on the icy road decreases. .
[0018]
If the pitch P of the fine grooves 6 is less than 0.5 mm, the wear of the fine grooves 6 can be promoted, but due to insufficient tread rigidity, the fine grooves 6 are crushed at the time of braking and driving, and the water film removal effect and snow removal ability are insufficient. become. On the other hand, when the pitch P of the fine grooves 6 exceeds 2.0 mm, the wear of the fine grooves 6 is delayed, and the area of the fine grooves 6 is reduced, so that the water film removing effect and the snow discharging ability are insufficient.
[0019]
The shape of the narrow groove 6 in plan view is not particularly limited, and can be zigzag as shown in FIG. 4 or wavy as shown in FIG. However, in the zigzag or wavy narrow groove, the angle with respect to the tire circumferential direction is specified based on the center line of the amplitude.
[0020]
The cross-sectional shape of the narrow groove 6 is not particularly limited, and may be other than the rectangle as shown in FIG. As shown in FIG. 5, when the edge part of the narrow groove 6 is made into the curved shape of the curvature radius R, snow removal capability can be improved. In addition, as shown in FIG. 6, it is possible to increase the snow drainage ability even when the width W 1 at the opening of the narrow groove 6 is larger than the width W 2 at the bottom.
[0021]
When the narrow groove 6 does not have a clear edge in the longitudinal section, the width W 1 at the opening is measured with reference to the intersection of the extension line of the groove side wall and the extension line of the tread surface, and at the bottom thereof. The width W 2 is measured on the basis of the intersection of the extension line of the groove side wall and the extension line of the groove bottom surface.
[0022]
Although the pneumatic tire for snowy and snowy roads having a block pattern has been described in the above embodiment, the present invention can also be applied to the case where ribs extending in the tire circumferential direction are provided as land portions partitioned into tread portions. .
[0023]
【Example】
In a pneumatic tire for ice and snowy road having a block pattern of a tire size 195 / 65R15, a plurality of fine grooves shallower than the sipe are formed on the tread surface of the block, and the angle θ with respect to the tire circumferential direction of these fine grooves, the shape in plan view, Conventional examples, comparative examples 1 and 2 and examples 1 to 4 in which the fine groove width W, fine groove pitch P, and fine groove depth D were set as shown in Table 1 were produced.
[0024]
These test tires were evaluated for braking performance on ice and initial wear by the following test methods, and the results are also shown in Table 1.
[0025]
Ice braking performance:
The test tire is mounted on a 2500cc rear-wheel drive vehicle with a rim size of 15 x 6.5 JJ and an air pressure of 200 kPa and equipped with an anti-lock brake system (ABS), and ABS braking is performed from a running state of 40 km / h on ice. The braking distance was measured. The evaluation results are shown as an index using the reciprocal of the measured value and using the conventional example as 100. A larger index value means a shorter braking distance.
[0026]
Initial wear resistance:
A test tire is attached to a vehicle with a rim size of 15 × 6.5 JJ and an air pressure of 200 kPa, and travels at an average speed of 35 km / h on a test course simulating a general road, and the remaining amount of narrow grooves is measured every 100 km. The distance traveled until the groove was worn out was measured. The evaluation results are shown as an index using the reciprocal of the measured value and using the conventional example as 100. A larger index value means faster wear of the narrow groove.
[0027]
[Table 1]
Figure 0003702958
As can be seen from Table 1, each of Examples 1 to 4 has superior braking performance on ice compared to the conventional example, and because the wear of the narrow groove is fast, the original characteristics of the tread rubber can be exhibited at an early stage. . On the other hand, Comparative Examples 1 and 2 were insufficient in improving the braking performance on ice.
[0028]
Next, in a pneumatic tire for snowy and snowy road having a block pattern with a tire size of 195 / 65R15, a plurality of fine grooves shallower than the sipe are formed on the tread surface of the block, and an angle θ of these fine grooves with respect to the tire circumferential direction is set to 45. The braking performance on ice was evaluated by the above-described test method while only the narrow groove depth D was changed while the narrow groove width W was 0.3 mm, the narrow groove pitch P was 1.0 mm, and the results are shown in FIG. 7 shows. However, the evaluation results are indicated by an index with 100 being D = 0.3 mm. From FIG. 7, it can be seen that good braking performance on ice can be obtained when the narrow groove depth D is in the range of 0.1 to 0.8 mm.
[0029]
Next, in a pneumatic tire for snowy and snowy road having a block pattern with a tire size of 195 / 65R15, a plurality of fine grooves shallower than the sipe are formed on the tread surface of the block, and an angle θ of these fine grooves with respect to the tire circumferential direction is set to 45. , The narrow groove depth D is 0.3 mm, the narrow groove pitch P is 1.0 mm, and only the narrow groove width W is changed, and the braking performance on ice is evaluated by the above-described test method. This is shown in FIG. However, the evaluation results are shown as an index with 100 being the case of W = 0.5 mm. It can be seen from FIG. 8 that good braking performance on ice can be obtained when the narrow groove width W is in the range of 0.1 to 0.8 mm.
[0030]
Next, in a pneumatic tire for snowy and snowy road having a block pattern with a tire size of 195 / 65R15, a plurality of fine grooves shallower than the sipe are formed on the tread surface of the block, and an angle θ of these fine grooves with respect to the tire circumferential direction is set to 45. , The narrow groove depth D is set to 0.3 mm, the narrow groove width W is set to 0.3 mm, and the braking performance on ice is evaluated by the above-described test method while only the narrow groove pitch P is changed. 9 shows. However, the evaluation results are shown as an index with 100 being P = 1.0 mm. From FIG. 9, it can be seen that good braking performance on ice can be obtained when the narrow groove pitch P is in the range of 0.5 to 2.0 mm.
[0031]
【The invention's effect】
As described above, according to the present invention, in a pneumatic tire for an snowy and snowy road in which a plurality of land portions made of blocks or ribs are defined in the tread portion and a plurality of sipes are provided on the land portions, A plurality of narrow grooves shallower than the sipe are formed on the surface, and the angle of the narrow grooves with respect to the tire circumferential direction is set to 42 to 60 °, so that the braking / driving performance on the ice road at the initial stage of wear is improved based on the narrow grooves. In addition, the original characteristics of the tread rubber can be exhibited at an early stage by rubbing the narrow grooves at an early stage. Therefore, the pneumatic tire for icy and snowy roads of the present invention can exhibit excellent braking / driving performance on icy roads even in an automobile equipped with an anti- lock brake system.
[Brief description of the drawings]
FIG. 1 is a development view showing a tread pattern of a pneumatic tire for an icy and snowy road according to an embodiment of the present invention.
2 is an enlarged plan view showing blocks in the tread pattern of FIG. 1. FIG.
FIG. 3 is a cross-sectional view of a block showing a narrow groove formed in the block of FIG. 2;
FIG. 4 is an enlarged plan view showing a block having zigzag narrow grooves.
FIG. 5 is a cross-sectional view of a block showing a chamfered narrow groove.
FIG. 6 is a cross-sectional view of a block showing a narrow groove with a wide opening.
FIG. 7 is a graph showing the relationship between the narrow groove depth D and the braking performance on ice.
FIG. 8 is a graph showing the relationship between narrow groove width W and braking performance on ice.
FIG. 9 is a graph showing the relationship between fine groove pitch P and braking performance on ice.
[Explanation of symbols]
1 Tread portion 2 Main groove 3 Horizontal groove 4 Block 5 Sipe 6 Narrow groove D Narrow groove depth W Narrow groove width P Narrow groove pitch θ Narrow groove angle

Claims (3)

トレッド部にタイヤ周方向に延びる複数本の主溝とタイヤ幅方向に延びる複数本の横溝とを設け、これら主溝及び横溝によって複数のブロックからなる陸部を区画したブロックパターンを有し、前記陸部に平面視でジグザグ形状をなしてタイヤ幅方向に延長する複数本のサイプを設けた氷雪路用空気入りタイヤにおいて、前記陸部のトレッド表面に前記サイプより浅い複数本の細溝を形成し、これら細溝のタイヤ周方向に対する角度を４２〜６０°とし、前記細溝の深さを０．１〜０．８ｍｍとし、前記細溝の幅を０．１〜０．８ｍｍとし、前記細溝のピッチを０．５〜２．０ｍｍとした氷雪路用空気入りタイヤ。The tread portion is provided with a plurality of main grooves extending in the tire circumferential direction and a plurality of horizontal grooves extending in the tire width direction, and has a block pattern in which a land portion composed of a plurality of blocks is defined by the main grooves and the horizontal grooves, In a pneumatic tire for icy and snowy roads that is provided with a plurality of sipes extending in the tire width direction in a zigzag shape in plan view on the land portion, a plurality of narrow grooves shallower than the sipes are formed on the tread surface of the land portion. The angle of these narrow grooves with respect to the tire circumferential direction is 42 to 60 °, the depth of the narrow grooves is 0.1 to 0.8 mm, the width of the narrow grooves is 0.1 to 0.8 mm, A pneumatic tire for snowy and snowy roads with a pitch of fine grooves of 0.5 to 2.0 mm . 前記細溝の縁部を湾曲形状にした請求項１に記載の氷雪路用空気入りタイヤ。The pneumatic tire for icy and snowy roads according to claim 1 , wherein the edge of the narrow groove is curved. 前記細溝の開口部での幅を底部での幅より大きくした請求項１又は２に記載の氷雪路用空気入りタイヤ。The pneumatic tire for ice and snowy road according to claim 1 or 2 , wherein a width at the opening of the narrow groove is larger than a width at the bottom.
JP2002197618A 2002-07-05 2002-07-05 Pneumatic tire for icy and snowy roads Expired - Lifetime JP3702958B2 (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
JP2002197618A JP3702958B2 (en) 2002-07-05 2002-07-05 Pneumatic tire for icy and snowy roads
EP03733570A EP1520733B1 (en) 2002-07-05 2003-06-25 Pneumatic tire for ice-bound or snow-covered road
CA2491957A CA2491957C (en) 2002-07-05 2003-06-25 Pneumatic tire for ice-bound or snow-covered road
EP08165096A EP2014486A2 (en) 2002-07-05 2003-06-25 Pneumatic tire for ice-bound or snow-covered road
DE60329843T DE60329843D1 (en) 2002-07-05 2003-06-25 AIR TIRES FOR VERESIS OR SNOW-COVERED ROADS
AT03733570T ATE446859T1 (en) 2002-07-05 2003-06-25 AIR TIRES FOR ICEY OR SNOW-COVERED ROADS
PCT/JP2003/008017 WO2004005051A1 (en) 2002-07-05 2003-06-25 Pneumatic tire for ice-bound or snow-covered road
US10/513,223 US7438100B2 (en) 2002-07-05 2003-06-25 Pneumatic tire for ice-bound or snow-covered road

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