JPH0732819A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To make compatible the wetness characteristic and the low-noise characteristic which are in antinomy relation to each other as far as the tread pattern is concerned, by forming main grooves in the tread of a pneumatic tire that circumferentially extend and by forming fine grooves in the side walls of the main grooves that extend along the main grooves. CONSTITUTION:A plurality of main grooves (straight grooves) 1 are formed in the pneumatic tire in such a manner as to extend circumferentially of a tread T. Further, fine grooves 2 are formed in the side wall of each main groove 1 in such a manner as to extend along the main groove 1. Columnar tube resonance vibrations which during the travel of the pneumatic tire occur due to the vibrations of the tread portion T caused by uneveness of the road surface are suppressed by the fine grooves 2. Further, simultaneously, the vibrations caused at the groove bottom 3 of each main groove 1 are also suppressed. Furthermore, the wetness characteristic (water expellency) as veiwed from each main groove 1 is also improved. As a result of the pattern noise in the pneumatic tire is decreased.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、走行中に発生する騒
音、所謂パターンノイズを低減するようにしたトレッド
に実質周方向に延びる主溝を有する空気入りタイヤに関
する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having a main groove extending substantially in the circumferential direction on a tread designed to reduce noise generated during running, so-called pattern noise.

【０００２】[0002]

【従来の技術】従来から存在するタイヤトレッドに施さ
れるパターンの主要機能の一つとして、ウエット路面上
におけるタイヤ走行中の排水性の確保が重要であり、こ
の点を念頭に置いてタイヤの外観にあわせて考慮した種
々なトレッドパターンが開発されてきた。最近のストレ
ート溝、即ちトレッドに実質周方向に延びる溝を備えた
トレッドパターンもその典型的なものである。2. Description of the Related Art As one of the main functions of a pattern that has been conventionally applied to a tire tread, it is important to ensure drainage while the tire is running on a wet road surface. Various tread patterns have been developed in consideration of the appearance. A typical example is a recent straight groove, that is, a tread pattern having a groove extending substantially in the circumferential direction on a tread.

【０００３】[0003]

【発明が解決しようとする課題】しかしながら、そのよ
うなトレッドに実質周方向に延びる溝の存在によってト
レッド面からの排水性はよくなり、その結果、ウエット
性は著しく向上するが、一方、接地面面内に路面とトレ
ッドに実質周方向に延びる溝の壁面によって構成される
気柱管が形成され、路面凹凸によってトレッドが加振さ
れると、この気柱管で共鳴が発生し、タイヤ騒音の大き
な要因となる。この気柱管共鳴音はトレッドに実質周方
向に延びる溝のボリュームと比例し、ボリュームが増加
すると、気柱管共鳴音レベルも増加する。逆にウエット
性はその溝のボリュームの増加によって良化方向に向か
うため、溝ボリュームはなるべく減少させずに如何して
低騒音化を図るかが問題であった。本発明は、上記の問
題点を解消するために創案されたものであり、その背反
関係にあるウエット性と低騒音性を両立することができ
るトレッドパターンを有する空気入りタイヤを提供する
ことを目的とする。However, the presence of the grooves extending substantially in the circumferential direction in such a tread improves the drainage property from the tread surface, and as a result, the wettability is remarkably improved, while the ground contact surface is improved. An air column tube formed by the wall surface of the groove extending substantially in the circumferential direction on the road surface and the tread is formed in the surface, and when the tread is vibrated by the road surface irregularities, resonance occurs in this air column tube, which causes tire noise. It becomes a big factor. This air columnar resonance sound is proportional to the volume of the groove extending substantially in the circumferential direction on the tread, and as the volume increases, the air columnar resonance sound level also increases. On the contrary, since the wettability is improved by increasing the volume of the groove, there is a problem how to reduce the noise without reducing the groove volume as much as possible. The present invention was created in order to solve the above problems, and an object thereof is to provide a pneumatic tire having a tread pattern that can achieve both anti-wetting property and low noise property. And

【０００４】[0004]

【課題を解決するための手段】上記目的を達成するため
に、本発明の空気入りタイヤにおいては、トレッドに実
質周方向に延びる主溝を配置する一方、その主溝の溝壁
に主溝に沿って延びる実質連続した細溝を配置したもの
が提供される。上記主溝の溝壁に主溝に沿って延びる実
質連続した細溝は幅ｗ，深さｈとすると、 細溝幅 ： ０．０５×Ｈ≦ｗ≦０．５×Ｈ（Ｈ：主溝深さ）……（１） 細溝深さ： ０．０５×Ｗ≦ｈ≦０．３×Ｗ（Ｗ：リブ幅） ……（２） の範囲にあるのが好ましい。また、１つの溝側面に複数
本の細溝が入る場合、その細溝幅を合計した値が（１）
の範囲にあるのが望ましい。To achieve the above object, in the pneumatic tire of the present invention, a main groove extending substantially in the circumferential direction is arranged on the tread, and the main groove is formed on the groove wall of the main groove. An arrangement of substantially continuous slots extending along the same is provided. When the width w and the depth h are the substantially continuous narrow grooves extending along the main groove on the groove wall of the main groove, the narrow groove width is: 0.05 × H ≦ w ≦ 0.5 × H (H: main groove Depth) (1) Fine groove depth: 0.05 × W ≦ h ≦ 0.3 × W (W: rib width) (2) In addition, when a plurality of narrow grooves are placed on one groove side surface, the total value of the narrow groove widths is (1)
It is desirable to be in the range of.

【０００５】[0005]

【作用】空気入りタイヤにあっては、トレッドに実質周
方向に延びる主溝、即ちストレート溝に起因する気柱管
共鳴音は７００Ｈｚから１２００Ｈｚ付近で顕著に発生
する。またそのようなストレート溝を有するタイヤのタ
イヤ騒音を路面凹凸の粗さの異なる２種の路面で計測す
ると、図１に示すように気柱管共鳴音の周波数領域で粗
い路面の方が騒音レベルが大となる。これは路面凹凸入
力によりトレッド部振動が励起され気柱管共鳴管が発生
したものと考えられる。また、この粗い路面上でタイヤ
転動時にストレート溝面内振動を計測すると、特に溝底
面での振動が大きくなっていることが判り、気柱管共鳴
管の低減にはこの溝底振動の低減が有効となる。ここ
で、この溝底振動を低減させる方法を鋭意検討したとこ
ろ、ストレート溝付近の圧縮剛性の低下が効果的であ
り、トレッドに実質周方向に延びる主溝の溝壁に主溝に
沿って延びる実質連続した細溝を付加することで、溝底
の振動が低減され、騒音レベルの低下が確認された。こ
の効果は細溝幅ｗが０．０５×Ｈ（Ｈは主溝の深さ）よ
り小さい場合、または細溝深さｈが０．０５×ｗ（ｗは
リブ幅）より小さいと効果が少なくなる。さらにｗが
０．５０×Ｈより大きい場合か或いはｈが０．３×ｗよ
り大きくなるとリブ部の耐久性が著しく損なわれること
も判った。In the pneumatic tire, the air columnar resonance noise caused by the main groove extending substantially circumferentially in the tread, that is, the straight groove is remarkably generated in the vicinity of 700 Hz to 1200 Hz. Further, when the tire noise of a tire having such straight grooves is measured on two types of road surfaces having different roughnesses of road surface irregularities, as shown in FIG. 1, the noise level of the rough road surface is higher in the frequency region of the air column resonance noise. Is large. It is considered that the tread vibration was excited by the road surface unevenness input and the air column resonance tube was generated. In addition, when measuring the vibration in the straight groove surface when rolling the tire on this rough road surface, it was found that the vibration was particularly large at the groove bottom surface, and to reduce the air column resonance tube, this groove bottom vibration was reduced. Is effective. Here, when the method for reducing the groove bottom vibration was earnestly studied, it is effective to reduce the compression rigidity in the vicinity of the straight groove, and the groove wall of the main groove extending substantially circumferentially in the tread extends along the main groove. It was confirmed that the vibration of the groove bottom was reduced and the noise level was lowered by adding a substantially continuous narrow groove. This effect is less effective when the fine groove width w is smaller than 0.05 × H (H is the depth of the main groove) or when the fine groove depth h is smaller than 0.05 × w (w is the rib width). Become. It was also found that the durability of the rib portion is significantly impaired when w is larger than 0.50 × H or when h is larger than 0.3 × w.

【０００６】[0006]

【実施例】以下実施例について図面を参照して説明す
る。図１は台上タイヤ騒音に対する路面凹凸の違いよる
音圧レベルでの比較を示した図である。図２は本発明の
実施例１の要部を示した図である。図３は本発明の実施
例２の要部を示した図である。図４は台上タイヤ騒音ス
ペクトル結果を示した図である。図２はトレッドＴの周
方向に延びる２本の主溝（ストレート溝）を有するタイ
ヤの実施例１で、主溝１の溝壁に主溝１に沿って細溝２
が延びており、その溝２によって走行中における路面凹
凸入力にトレッド部Ｔの振動が励起されて発生する気柱
管共鳴音を低減し、タイヤ転動時における主溝１の溝底
３の振動を抑制している。その場合における細溝深さｈ
＝４mm，細溝深さｗ＝２mm，主溝の深さＨ＝９mm，最大
幅Ｂ＝１２mm，主溝間の距離Ｗ＝３０mmである。実施例
２が図３に示されており、２本の主溝１，１の内、一方
は上下に２段に細溝２₁ ，２₂ が設けられており、他方
は若干大きな溝２が側壁に周方向に穿設されている。こ
れらの溝２は実質上連続して設けられていればよい。次
に、図２に示す実施例１及び溝壁に細溝２がない従来例
をタイヤサイズ２２５／５０Ｒ１６のタイヤに適用して
単体台上試験を行い、騒音を台上騒音計測用ドラムで計
測評価し、ウエット性は実車走行による水深１０mmの水
溜まり上を直進走行させ、ハイドロプレーニングが生じ
る最低速度を測定し評価した。その結果を示すと以下の
とおりである。Embodiments will be described below with reference to the drawings. FIG. 1 is a diagram showing a comparison of sound pressure levels due to differences in road surface unevenness with respect to bench tire noise. FIG. 2 is a diagram showing a main part of the first embodiment of the present invention. FIG. 3 is a diagram showing a main part of a second embodiment of the present invention. FIG. 4 is a diagram showing the results of the tire noise spectrum on the bench. FIG. 2 shows Example 1 of a tire having two main grooves (straight grooves) extending in the circumferential direction of the tread T, in which a groove 2 along the main groove 1 is formed on the groove wall of the main groove 1.
The air columnar resonance noise generated by the vibration of the tread portion T being excited by the road surface unevenness input during traveling by the groove 2 is reduced, and the vibration of the groove bottom 3 of the main groove 1 during tire rolling is reduced. Is suppressed. Fine groove depth h in that case
= 4 mm, fine groove depth w = 2 mm, main groove depth H = 9 mm, maximum width B = 12 mm, distance W = 30 mm between main grooves. Example 2 is shown in FIG. 3. Of the two main grooves 1 and 1, one is provided with fine grooves 2 ₁ and 2 ₂ vertically in two steps, and the other is provided with a slightly larger groove 2. The sidewall is provided in the circumferential direction. These grooves 2 may be provided substantially continuously. Next, Example 1 shown in FIG. 2 and a conventional example having no groove 2 on the groove wall were applied to a tire having a tire size of 225 / 50R16 to perform a single bench test, and noise was measured with a bench noise measurement drum. The wettability was evaluated by running straight on a water pool with a water depth of 10 mm by running an actual vehicle and measuring the minimum speed at which hydroplaning occurs. The results are shown below.

【０００７】 以上の結果から図４からも判るように周波数１０００Ｈ
ｚの所の音圧レベルで１．０ｄＢ減少していることが判
った。[0007] From the above results, as can be seen from FIG. 4, frequency 1000H
It was found that the sound pressure level at z was reduced by 1.0 dB.

【０００８】[0008]

【発明の効果】以上詳述したように本発明は構成されて
いるので、トレッドに実質周方向に延びる主溝を配置す
る一方、その主溝の溝壁に主溝に沿って延びる実質連続
した細溝を配置したことによって走行中におけるトレッ
ドの主溝からの排水性も改善されるとともに、路面凹凸
入力にトレッド部Ｔの振動が励起されて発生する気柱管
共鳴音が低減され、タイヤ転動時における主溝１の溝底
３の振動も抑制されるので、全体としてタイヤのパター
ンノイズの低減化に寄与する等の効果を奏するものであ
る。Since the present invention is configured as described above in detail, the main groove extending substantially in the circumferential direction is arranged on the tread, while the groove wall of the main groove extends substantially continuously along the main groove. By arranging the narrow grooves, drainage from the main groove of the tread during traveling is improved, and air columnar resonance noise generated by the vibration of the tread portion T excited by the road surface unevenness input is reduced, and the tire rolling Since the vibration of the groove bottom 3 of the main groove 1 during the movement is also suppressed, the effect such as contributing to the reduction of the tire pattern noise as a whole is exhibited.

【図面の簡単な説明】[Brief description of drawings]

【図１】台上タイヤ騒音に対する路面凹凸の違いよる音
圧レベルでの比較を示した図である。FIG. 1 is a diagram showing a comparison in sound pressure level due to a difference in road surface unevenness with respect to bench tire noise.

【図２】本発明の実施例１の要部を示した図である。FIG. 2 is a diagram showing a main part of the first embodiment of the present invention.

【図３】本発明の実施例２の要部を示した図である。FIG. 3 is a diagram showing a main part of a second embodiment of the present invention.

【図４】台上タイヤ騒音スペクトル結果を示した図であ
る。FIG. 4 is a diagram showing a result of a tire noise spectrum on a bench.

【符号の説明】[Explanation of symbols]

１ 主溝 ２ 細溝 ２₁ 細溝 ２₂ 細溝 ３ 溝底 Ｔ トレッド1 main groove 2 narrow groove 2 ₁ narrow groove 2 ₂ narrow groove 3 groove bottom T tread

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】 トレッドに実質周方向に延びる主溝を配
置する一方、その主溝の溝壁に主溝に沿って延びる実質
連続した細溝を配置したことを特徴とする空気入りタイ
ヤ。1. A pneumatic tire characterized in that a main groove extending substantially circumferentially is arranged on a tread, and a substantially continuous narrow groove extending along the main groove is arranged on a groove wall of the main groove.