JP3595411B2 - Noise simulation method and simulator - Google Patents

Noise simulation method and simulator Download PDF

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JP3595411B2
JP3595411B2 JP10036996A JP10036996A JP3595411B2 JP 3595411 B2 JP3595411 B2 JP 3595411B2 JP 10036996 A JP10036996 A JP 10036996A JP 10036996 A JP10036996 A JP 10036996A JP 3595411 B2 JP3595411 B2 JP 3595411B2
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road surface
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tread
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JPH09288002A (en
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英史 山田
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Bridgestone Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
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Description

【０００１】
【発明の属する技術分野】
本発明は騒音シミュレート方法及びシミュレータに係り、特に、忠実度が高いタイヤ騒音やロードノイズ等の車内騒音を発生することができる騒音シミュレート方法及び騒音シミュレータに関する。
【０００２】
【従来の技術及び発明が解決しようとする課題】
タイヤ騒音を発生させる原因としては、タイヤのトレツドに設けられた複数の負荷支持部（ブロック）による打撃音、路面の表面形状（路面形状）の凹凸によるタイヤ加振音、接地面内でのタイヤのすべりによるすべり音等が主な成分として考えられている。
【０００３】
タイヤのトレツドに設けられたブロックによる打撃音をシミュレートした技術としては、特開平４−１４８８４０号公報に記載された技術が知られている。
【０００４】
しかしながら、タイヤ騒音に占める路面形状の凹凸によるタイヤ加振成分の寄与率は高いことが知られている。従って、より忠実にタイヤ騒音をシミュレートするためには、この路面形状の凹凸によるタイヤ加振成分を考慮することが重要になる。
【０００５】
また、車両走行時に路面形状が変化したときの車内騒音の聴感上の変化も大きいことが知られているので、路面形状の凹凸が原因でタイヤ軸が振動し、車内に振動が伝達して発生する車内騒音であるロードノイズをシミュレートするためにも、この路面形状の凹凸によるタイヤ加振成分を考慮することが重要になる。
【０００６】
本発明は上記問題点を解決すべくなされたもので、単一の微小突起が回転中のタイヤに入力したとき及び入力した単一の微小突起がタイヤから離れるときの音圧の減衰波形、または車内騒音の波形を基準に定式化した波形をトレッドの路面との接触部（フットプリント）の輪郭（接地輪郭）とタイヤパターンの影響とを考慮して合成することにより、忠実度の非常に高いタイヤ騒音または車内騒音を発生することができる騒音シミュレート方法及びシミュレータを提供することを目的とする。
【０００７】
【課題を解決するための手段】
上記目的を達成するために請求項１の発明は、トレッドを表す２次元のトレッドデータ及び多数の微小突起の位置を表す路面形状データに基づいて、トレツドに複数の負荷支持部を有するタイヤが多数の微小突起を備えた路面上を回転するときに発生する騒音をシミュレートする騒音シミュレート方法であって、トレッドの路面との接触部の輪郭でかつタイヤが回転するときにタイヤの路面と接触していない部分が路面と接触する側の輪郭である接触部前縁の輪郭と、トレッドの路面との接触部の輪郭でかつタイヤが回転するときにタイヤの路面と接触している部分が路面から離れる側の輪郭である接触部後縁の輪郭とを定め、接触部前縁の輪郭及び接触部後縁の輪郭がトレッドの周方向に移動するように接触部前縁の輪郭及び接触部後縁の輪郭とトレッドとが相対移動したと仮定して、一方の値が微小突起に対応する２値の列で構成されかつ単位長さ当たりの微小突起の個数を表す数列を、接触部前縁の輪郭及び接触部後縁の輪郭の各々に沿った単位長さ毎に接触部前縁の輪郭及び接触部後縁の輪郭の各々に設定し、接触部前縁の輪郭と負荷支持部とが交わった部分における前記一方の値の総数と路面の粗さを表す係数とに基づいた振幅及び接触部後縁の輪郭と負荷支持部とが交わった部分における前記一方の値の総数と路面の粗さを表す係数とに基づいた振幅を有する音の波形の各々を位相を考慮して定め、定められた音の波形をトレッド全面にわたって積算し、積算された波形に基づいて可聴音を発生させるものである。
【０００８】
請求項２の発明は、請求項１の発明において、負荷支持部のエッジでかつタイヤが回転するときに最初に路面と接触する側のエッジである踏込側エッジと、負荷支持部のエッジでかつタイヤが回転するときに最後に路面と接触する側のエッジである蹴出側エッジとが区別できるように前記トレッドデータを表し、接触部前縁の輪郭及び接触部後縁の輪郭がトレッドの周方向に移動するように接触部前縁の輪郭及び接触部後縁の輪郭とトレッドとが相対移動したと仮定して、踏込側エッジの単位時間に接触部前縁の輪郭と交わる部分と蹴出側エッジの単位時間に接触部後縁の輪郭と交わる部分とを音源とする音の波形の各々を位相を考慮して更に定め、定められた音の波形及び請求項１で定められた音の波形をトレッド全面にわたって積算し、積算された波形に基づいて可聴音を発生させるものである。
【０００９】
請求項３の発明は、トレッドを表す２次元のトレッドデータ及び多数の微小突起の位置を表す路面形状データに基づいて、トレツドに複数の負荷支持部を有するタイヤが多数の微小突起を備えた路面上を回転するときに発生する騒音をシミュレートする騒音シミュレータであって、トレッドの路面との接触部の輪郭でかつタイヤが回転するときにタイヤの路面と接触していない部分が路面と接触する側の輪郭である接触部前縁の輪郭と、トレッドの路面との接触部の輪郭でかつタイヤが回転するときにタイヤの路面と接触している部分が路面から離れる側の輪郭である接触部後縁の輪郭とを定める輪郭決定手段と、接触部前縁の輪郭及び接触部後縁の輪郭がトレッドの周方向に移動するように接触部前縁の輪郭及び接触部後縁の輪郭とトレッドとが相対移動したと仮定して、一方の値が微小突起に対応する２値の列で構成されかつ単位長さ当たりの微小突起の個数を表す数列を、接触部前縁の輪郭及び接触部後縁の輪郭の各々に沿った単位長さ毎に接触部前縁の輪郭及び接触部後縁の輪郭の各々に設定する設定手段と、接触部前縁の輪郭と負荷支持部とが交わった部分における前記一方の値の総数と路面の粗さを表す係数とに基づいた振幅及び接触部後縁の輪郭と負荷支持部とが交わった部分における前記一方の値の総数と路面の粗さを表す係数とに基づいた振幅を有する音の波形の各々を位相を考慮して決定する波形決定手段と、決定された音の波形をトレッド全面にわたって積算する積算手段と、積算された波形に基づいて可聴音を発生させる音発生手段と、で構成したものである。
【００１０】
そして、請求項４の発明は、請求項３の発明において、負荷支持部のエッジでかつタイヤが回転するときに最初に路面と接触する側のエッジである踏込側エッジと、負荷支持部のエッジでかつタイヤが回転するときに最後に路面と接触する側のエッジである蹴出側エッジとが区別できるように前記トレッドデータを表し、前記波形設定手段において、接触部前縁の輪郭及び接触部後縁の輪郭がトレッドの周方向に移動するように接触部前縁の輪郭及び接触部後縁の輪郭とトレッドとが相対移動したと仮定して、踏込側エッジの単位時間に接触部前縁の輪郭と交わる部分と蹴出側エッジの単位時間に接触部後縁の輪郭と交わる部分とを音源とする音の波形の各々を位相を考慮して更に決定し、前記積算手段において、決定された音の波形及び請求項１で決定された音の波形をトレッド全面にわたって積算し、前記音発生手段において、積算された波形に基づいて可聴音を発生させるようにしたものである。
【００１１】
トレッドを表す２次元のトレッドデータ及び多数の微小突起の位置を表す路面形状データに基づいて、トレツドに複数の負荷支持部を有するタイヤが多数の微小突起を備えた路面上を回転するときに発生するタイヤ騒音や車内騒音をシミュレートする際に、回転しているタイヤの路面形状の凹凸による騒音は、微小突起がトレッドに入力するとき及びトレッドに入力している微小突起がトレッドから離れるとき発生する。このため、請求項１、３の発明では、トレッドの路面との接触部（フットプリント）の輪郭でかつタイヤが回転するときにタイヤの路面と接触していない部分が路面と接触する側の輪郭である接触部前縁の輪郭に微小突起が入力したとき、及びトレッドの路面との接触部の輪郭でかつタイヤが回転するときにタイヤの路面と接触している部分が路面から離れる側の輪郭である接触部後縁の輪郭から微小突起が離れるときに音が発生すると仮定する。
【００１２】
また、発生する音の振幅は、接触部前縁の輪郭と負荷支持部とが交わった部分及び接触部後縁の輪郭と負荷支持部とが交わった部分における微小突起の個数及び路面の粗さに影響される。このため、接触部前縁の輪郭及び接触部後縁の輪郭がトレッドの周方向に移動するように接触部前縁の輪郭及び接触部後縁の輪郭とトレッドとが相対移動したと仮定して、一方の値が微小突起に対応する２値の列で構成されかつ単位長さ当たりの微小突起の個数を表す数列を、接触部前縁の輪郭及び接触部後縁の輪郭の各々に沿った単位長さ毎に接触部前縁の輪郭及び接触部後縁の輪郭の各々に設定する。そして、接触部前縁の輪郭と負荷支持部とが交わった部分における一方の値の総数と路面の粗さを表す係数とに基づいた振幅及び接触部後縁の輪郭と負荷支持部とが交わった部分における一方の値の総数と路面の粗さを表す係数とに基づいた振幅を有する音の波形の各々を位相を考慮して定め、定められた音の波形をトレッド全面にわたって積算し、積算された波形に基づいて可聴音を発生させる。
【００１３】
請求項１、３の発明では、接触部前縁の輪郭及び接触部後縁の輪郭に微小突起が入力したとき、及び入力していた微小突起が接触部前縁の輪郭及び接触部後縁の輪郭から離れるときに音が発生すると仮定しているため、タイヤ騒音の発生部位を特定することができ、従って各音源から発生する音の位相を考慮して積算することにより音の合成をすることができる。
【００１４】
なお、接触部前縁の輪郭と接触部後縁の輪郭は、タイヤ径、タイヤに作用する荷重等のタイヤに関するデータを用いて求めてもよく、実際に接触部の輪郭を測定して決定してもよく、更に接触部の輪郭を光学的に測定して決定してもよい。
【００１５】
また、回転しているタイヤの負荷支持部の打撃による騒音は、負荷支持部が路面と接触するとき及び路面と接触している負荷支持部が路面から離れるときに発生するため、請求項２、４の発明では、更に、タイヤ騒音の音源となる部位が、負荷支持部のエッジでかつタイヤが回転するときに最初に路面と接触する側のエッジである踏込側エッジと、負荷支持部のエッジでかつタイヤが回転するときに最後に路面と接触する側のエッジである蹴出側エッジにも存在すると仮定する。このため、請求項２、４の発明ではこの踏込側エッジと蹴出側エッジとが区別できるようにトレッドデータを表す。そして、接触部前縁の輪郭及び接触部後縁の輪郭がタイヤの周方向に移動するように、接触部前縁の輪郭及び接触部後縁の輪郭とトレッドとが相対移動したと仮定して、踏込側エッッジの単位時間に接触部前縁の輪郭と交わる部分と蹴出側エッジの単位時間に接触部後縁の輪郭と交わる部分とを音源とする。次に、各音源から発生する音の波形を位相を考慮して定め、この定められた音の波形と請求項１、３で求められた音の波形とをトレッド全面にわたって積算する。
【００１６】
請求項２、４の発明でも踏込側エッジと蹴出側エッジとに音源となる部位が存在すると仮定しているため、タイヤ騒音の発生部位を特定することができ、従って各音源から発生する音の位相を考慮して音を合成することができる。そして、積算された波形に基づいて可聴音を発生させる。
【００１７】
上記各発明におけるタイヤ騒音を発生させる音源の振動は、負荷支持部からトレッドゴムを介してサイドウォールに伝達されて減衰し、このときの振動が空気中を伝播してタイヤ騒音として観測者に聴取されるので、音の波形は、タイヤの音の伝達特性を考慮して減衰波形で定めるのがよい。また、車内騒音をシュミレートする場合には、車内で聴取される騒音を表す波形で定めればよい。
【００１８】
【発明の実施の形態】
以下図面を参照して本発明の実施の形態を詳細に説明する。
【００１９】
図１は本発明の実施の形態のタイヤシミュレータのブロック図を示すものである。このシミュレータは、シミュレーションを行なうパーソナルコンピュータ１０を備えている。パーソナルコンピュータ１０には、インタフェース１２、ローパスフィルタ及びアンプを備えた信号処理回路１４を介してタイヤ騒音を聴取するためのヘッドホン１６が接続されている。また、パーソナルコンピュータ１０は、アダプタ１８を介してＣＡＤによりタイヤのトレッドパターン等を設計するためのタイヤ設計システムのホストコンピュータに接続されている。
【００２０】
次に、本実施の形態のシミュレーションの原理を説明する。図２は、ｘ軸をタイヤの周方向にとり、ｙ軸をタイヤの回転軸と平行な方向にとったｘｙ平面上に表されたトレッドパターンの平面図を示し、本実施の形態では、トレッドパターンを図２に示すｘｙ平面上に２次元のデジタルデータで表している。
【００２１】
また、フットプリント２２の前縁の輪郭４０、すなわちフットプリントの輪郭でかつタイヤが回転するときにタイヤの路面と接触していない部分が路面と接触する側の輪郭と、フットプリントの後縁の輪郭４２、すなわちフットプリントの輪郭でかつタイヤが回転するときにタイヤの路面と接触している部分が路面から離れる側の輪郭とをｘｙ平面上の関数ｆ１ （ｘ）、ｆ２ （ｘ）で表す。これらの関数は、フットプリントの輪郭の演算等によって定めることができる。
【００２２】
図３（１）はスムーズタイヤ（ブロックパターンを有していないタイヤ）をタイヤ回転軸と垂直な平面で切断した、タイヤの路面との接触部（フットプリント）の近傍で単一微小突起２９がタイヤの接地面内のセンター部分に入力した状態と、センター部分に入力していた単一微小突起２９がタイヤから離れた状態とを示す断面図である。なお、２５はタイヤの表面を示す。
【００２３】
単一微小突起２９がタイヤの接地面内のセンター部分に入力したときに発生する音圧の時間軸波形を図３から観察すると、単一微小突起２９がフットプリントの前縁の輪郭４０に入力する瞬間にピークとなる減衰波形になっている。なお、単一微小突起２９がフットプリントの後縁の輪郭４２から離れる瞬間においてもピークとなる減衰波形になっている。
【００２４】
従って、次のようにして車両が路面を走行しているときのタイヤ騒音をシミュレートすることができる。
【００２５】
まず、多数の単一微小突起がランダムに合成されて路面形状が形成されていると仮定して、多数の微小突起の位置を２次元上（ｘｙ平面上）に表し、路面粗さ（各位置における微小突起の大きさ）をｚ方向に表した３次元の路面データを生成する。また、フットプリントの前縁の輪郭（または後縁の輪郭）上に位置する複数の微小突起の各々からは同時に音が発生すると仮定する。
【００２６】
図３（１）では単一微小突起が入力されかつ他の単一微小突起が離れた瞬間の減衰波形を示しているが、この減衰波形の振幅は同時に入力される微小突起、または同時に離れる微小突起の個数が多くなる程大きくなる。従って、この同時に音を発生する微小突起の個数を表すために、単位長さ当たりの微小突起の個数、すなわち微小突起の密度を考慮する。この微小突起の密度は、図３（２）に示すように、フットプリントの前縁の輪郭（または後縁の輪郭）に沿った路面粗さを表す波形とこの波形の２乗平均の正の平方根（ｒｍｓ値）との交点で、かつこの波形の時間微分値が正のポイントの単位長さ当たりの個数で定義することができる。なお、微小突起の密度は、単位長さ当たりの単一微小突起の実際の個数で表すこともできる。
【００２７】
また、この微小突起の密度をディジタルデータで表すために、微小突起に対応する１と微小突起以外の部分に対応する０とからなる２値の乱数列を用い、この乱数列の０と１の総数に対する１の総数の割合が、この微小突起の密度に対応するように乱数列を設定する。例えば、乱数列「１１００１」、「００１１１」は各々密度０．６を意味している。なお、本実施の形態では、数列として０と１とがランダムに配列される乱数列を用いているが、予め定められた順序の数列を用いるようにしてもよく、０を微小突起に対応させてもよい。
【００２８】
また、負荷支持部と負荷支持部との間の溝部に入力した微小突起はタイヤを加振しないことから音源とならないので、フットプリントの前縁の輪郭と負荷支持部とが交わった部分における１の値の総数及びフットプリントの後縁の輪郭と負荷支持部とが交わった部分における１の値の総数が減衰波形の振幅を決定する１つの値になる。
【００２９】
さらに、減衰波形の振幅は路面の凹凸の振幅、すなわち路面粗さに影響されるので、路面粗さに基づいた係数として路面感度係数を考慮する。この路面感度係数は、負荷支持部の剛性、トレッドゴムの物性、及び路面粗さ等から演算により求めることができ、この路面感度係数は減衰波形の振幅を決定する他の１つの値になる。
【００３０】
なお、この路面感度係数は、路面凹凸の振幅が小さい路面（セーフティーウォーク路）や実際の路面に近い路面粗さを有するドラム表面（疑似アスファルト路）等の各種のシミュレート対象となる路面に応じた一定値を予め定めておくこともできる。この場合には、路面形状データとして路面粗さのデータは必要なくなるので、多数の微小突起の位置を表す２次元の路面形状データを使用すればよい。
【００３１】
上記のように、減衰波形の振幅は、微小突起の密度及び路面感度係数に影響されるので、微小突起の密度と路面感度係数との積を振幅とするフットプリントの前縁の輪郭の音圧減衰波形及びフットプリントの後縁の輪郭の音圧減衰波形の各々を時間遅れ、すなわち位相差を考慮して決定し、この決定された波形をトレッド全面にわたって合成することで、車両がこの路面を走行しているときのタイヤ騒音をシミュレートできる。
【００３２】
実際のタイヤが転動していく状態を表すために、フットプリント２２をｘ軸に沿ってタイヤの速度（タイヤが転動するときの水平方向の移動速度）に応じて単位距離ΔＤずつ正方向に移動させる。図４は、フットプリントの前縁の輪郭４０とフットプリントの後縁の輪郭４２とが交った負荷支持部を拡大して示す図であり、時刻ｔｉ のフットプリント、すなわちｉ番目のフットプリントが単位距離ΔＤ移動して時刻ｔｉ＋１ の位置、すなわちｉ＋１番目の位置に移動した状態を示している。このフットプリントは、単位距離ΔＤを単位時間ΔＴで移動する。
【００３３】
時刻ｔｉ のフットプリントの前縁の輪郭４０上に路面密度から決定される１と０との乱数列を単位長さ毎に前縁の輪郭４０の全体にわたって設定する。
【００３４】
このように設定した乱数列の中で、溝部２６上に位置する乱数１は、音源にならないので、図５に示すように０に変換し、前縁の輪郭４０上に位置する１の総数Ｎｉを演算する。同様に、時刻ｔｉ のフットプリントの後縁の輪郭４２についても１の総数Ｍｉを演算する。
【００３５】
そして、以下の減衰波形を決定する。
Ｆｉ ＝Ｎｉ ・ＰＦ ・ｅｘｐ［−ａｔ］ｓｉｎｂｔ・・・（１）
Ｋｉ ＝Ｍｉ ・ＰＫ ・ｅｘｐ［−ｃｔ］ｓｉｎ（ｄｔ−φ）・・・（２）
ただし、
ＰＦ ：前縁の輪郭、すなわち踏み込み部における音の路面感度係数
ＰＫ ：後縁の輪郭、すなわち蹴りだし部における音の路面感度係数
ａ ：踏み込み部の音の減衰係数
ｃ ：蹴りだし部の音の減衰係数
ｂ ：踏み込み部の音の周波数
ｄ ：蹴りだし部のの音の周波数
φ ：踏み込み部から発生する音に対する蹴りだし部から発生する音の位相差であり、Ｎｉ ・ＰＦ は踏み込み部の音の波形の音圧レベル（ピークからピークまでの値、すなわち振幅の２倍）、Ｍｉ ・ＰＫ は踏み込み部の音の波形の音圧レベルを表す。
【００３６】
この減衰係数ａ、ｃ及び周波数ｂ、ｄはトレッドゴムの物性及びタイヤの伝達特性によって定まり、位相差φはフットプリントの長さとタイヤの移動速度とで定まる踏み込み部で発生する音と蹴りだし部で発生する音との発生時間差（図３のΔｔ）で定まるが、上記減衰係数、周波数及び位相差は実験によって定めるのが好ましく、例えば、ａ＝０．２４×１０３ 、ｂ＝１２００−４００ｔのように時間の関数で定めるのが好ましい。
【００３７】
そして、この総数Ｎｉ 、Ｍｉ を時刻ｔｉ＋１ 、時刻ｔｉ＋２ 時刻ｔｉ＋３ 、・・・と順に求め、上記（１）、（２）式で定まる音の波形をｘｙ平面上に表わされたトレッド全面にわたって合成し、合成値に基づいて可聴音を発生させる。これによって、路面形状の凹凸によるタイヤ加振音の波形を決定することができる。
【００３８】
また、本実施の形態では、タイヤのトレツドに設けられた複数の負荷支持部による打撃音の波形を求めるために、トレッドの負荷支持部２４の踏込側エッジ２８及び蹴出側エッジ３０とが区別できるようにトレッドパターンを図２に示すｘｙ平面上に２次元のデジタルデータで表す。この踏込側エッジ２８は、図６に示すように、負荷支持部２４のエッジでかつタイヤが回転するときに最初に路面と接触する側のエッジ、すなわち最初に路面と接触する側のエッジである。また、蹴出側エッジ３０は、負荷支持部２４のエッジでかつタイヤが回転するときに最後に路面と接触する側のエッジ、すなわち最後に路面から離れる側のエッジである。なお、２６は溝部である。
【００３９】
図７は、図４と同様の平面図である。図７において、負荷支持部２４の踏込側エッジ２８が、単位時間ΔＴ内にフットプリント前縁の輪郭４０と交わった交差部位をＬｉ１、Ｌｉ２、Ｌｉ３、・・・（一般式で、Ｌｉｋ）と表す。なお、１、２、３、・・・（＝ｋ）は踏込側エッジ２８のフットプリントの前縁の輪郭と交わった交差部位に対して、ｙ軸の正方向に順に付けた番号である。また、負荷支持部２４の蹴出側エッジ３０の単位時間ΔＴ内にフットプリントの後縁の輪郭４２と交わった交差部位をＴｉ１、Ｔｉ２、Ｔｉ３、・・・（一般式で、Ｔｉｊ）と表す。なお、１、２、３、・・・（＝ｊ）は、蹴出側エッジ３０のフットプリントの後縁の輪郭４２と交わった交差部位に対して、ｙ軸方向に順に付した番号を表す。また、交差部位Ｌｉ１、Ｌｉ２、Ｌｉ３、・・・、Ｌｉｋ・・・のフットプリントの前縁の輪郭４０への投影長さをＡｉ１、Ａｉ２、Ａｉ３、・・・（一般式で、Ａｉｋ）と表し、交差部位Ｔｉ１、Ｔｉ２、Ｔｉ３、・・・、Ｔｉｊ・・・のフットプリント後縁の輪郭への投影長さをＢｉ１、Ｂｉ２、Ｂｉ３、・・・（一般式で、Ｂｉｋ）と表す。交差部位Ｌｉｋの各々から発生する音の波形を一般式で、下記の（３）式のようにｆｉｋで表し、交差部位Ｔｉｊの各々から発生する音の波形を下記の（４）式に示すようにｆｉｊで表す。
ｆｉｋ＝Ａｉｋｅｘｐ［−αｔ］ｓｉｎβｔ・・・（３）
ｆｉｊ＝Ｂｉｊｅｘｐ［−γｔ］ｓｉｎ（δｔ−Φ）・・・（４）
ただし、
Ａｉｋ：踏込側エッジの交差部位の音の波形の音圧レベル（ピークからピークまでの値、すなわち振幅の２倍）。この音圧レベルは衝撃力に対応する。
【００４０】
Ｂｉｊ：蹴出側エッジの交差部位の音の波形の音圧レベル
α ：踏込側エッジの交差部位の音の減衰係数
γ ：蹴出側エッジの交差部位の音の減衰係数
β ：踏込側エッジの交差部位の音の周波数
δ ：蹴出側エッジの交差部位の音の周波数
Φ ：踏込側エッジの交差部位から発生する音に対する蹴出側エッジの交差部位から発生する音の位相差
この音圧レベルＡｉｋ、Ｂｉｊは負荷支持部の剛性及びトレッドゴムの物性等によって定まり、減衰係数α、γ及び周波数β、δはトレッドゴムの物性及びタイヤの伝達特性によって定まり、位相差Φはフットプリントの長さとタイヤの移動速度とで定まる踏込側エッジで発生する音と蹴出側エッジで発生する音との発生時間差図６の（Δｔ）で定まるが、上記音圧レベル、減衰係数、周波数及び位相差は実験によって定めるのが好ましく、例えば、α＝３．３１６×１０３ 、β＝６．２４×１０３ である。
【００４１】
そして、上記（１）〜（４）式で定まる音の波形をｘｙ平面上に表わされたトレッド全面にわたって合成し、合成値に基づいて可聴音を発生させることにより、路面形状の凹凸によるタイヤ加振音及びタイヤのトレツドに設けられた複数の負荷支持部による打撃音を加味したタイヤの騒音をシミュレートするとができる。
【００４２】
次に図８を参照して上記原理によってタイヤ騒音シュミュレーションを行うパーソナルコンピュータ１０のルーチンを説明する。
【００４３】
ステップ１００において変数ｉ等のイニシャライズを行い、ステップ１０２においてアダプタ１８を介してホストコンピュータから入力されてＲＡＭに記憶されているデータ及びパーソナルコンピュータ１０のキーボードから入力されたデータを取込む。これらのデータとしては、タイヤ周長（タイヤが転動しているときの平均半径×２π）、タイヤ移動速度（タイヤが転動するときの水平方向の速度）、トレッドのｘｙ座標上パターン（踏込側エッジ２８及び蹴出側エッジ３０の位置を含む）を示すデータ、フットプリント２２の前縁の輪郭を表す関数ｙ＝ｆ１ （ｘ）、フットプリント２２の後縁の輪郭を表す関数ｙ＝ｆ２ （ｘ）、路面をランダムに配置された微小突起と仮定したときの路面粗さ及び微小突起の位置を表す３次元の路面形状データ等である。なお、関数ｆ１ （ｘ）、ｆ２ （ｘ）は入力することなく演算で求めてもよい。
【００４４】
次のステップ１０３では以下に示す（５）、（６）式に従ってサンプリング回数Ｎを演算する。
【００４５】
タイヤ１回転の時間＝タイヤ周長／タイヤ移動速度・・・（５）
Ｎ＝タイヤ１回転の時間／ΔＴ・・・（６）
なお、ΔＴはサンプリング時間であり、システムが取り扱うことができる入力信号に含まれる周波数成分の最大値は、サンプリング周波数の半分を超えることができない（ナイキストの定理）ので、このサンプリング時間はナイキストの定理を考慮して定められており、例えば５０μｓｅｃ である。
【００４６】
次のステップ１０６では詳細は後述するが、路面形状の凹凸によるタイヤ加振音の波形を決定する処理を実行し、ステップ１０８では詳細は後述するが、タイヤのトレツドに設けられた複数の負荷支持部による打撃音の波形を決定する処理を実行する。
【００４７】
次にステップ１０６の詳細を図９を参照して説明する。ステップ１４０では、３次元の路面形状データから関数ｙ＝ｆ１ （ｘ）、関数ｙ＝ｆ２ （ｘ）上の路面粗さを表す波形を求め、この波形とｒｍｓ値との交点でかつ路面粗さを表す波形の時間微分が正の単位長さ当たりのポイント数を単位長さ毎に求めて各々の路面の密度とし、これらの路面の密度を表す上記で説明した乱数列を路面の密度毎に作成し、時刻ｔｉ のフットプリントの前縁の輪郭４０上にこの乱数列を単位長さ毎に割り当てる。
【００４８】
なお、一定値の路面粗さを用いる場合には、一定の乱数列を単位長さ毎に割り当てればよい。
【００４９】
次のステップ１４２では、図５に示すように、この乱数列の中で、溝部２６上に位置する乱数１を０に変換する。
【００５０】
ステップ１４４では、フットプリントの前縁の輪郭４０上に位置する１の総数Ｎｉ、及びフットプリントの後縁の輪郭４２上に位置する１の総数Ｍｉを演算すると共に、路面粗さ、負荷支持部の剛性、トレッドゴムの物性等に基づいて路面感度係数を演算する。そして、ステップ１４６では、上記（１）式及び（２）式に従って減衰波形を決定する。
【００５１】
次のステップ１４８では、変数ｉを１インクリメントし、次のステップ１５０では変数ｉの値がステップ１００でイニシャライズされた初期値であるか否かを判断し、初期値のときはステップ１５２で負荷支持部２４の各々の踏込側エッジ２８と時刻ｔｉ のフットプリント前縁の輪郭を表す関数ｆ１ （ｘ）との交点座標を求めると共に、負荷支持部２４の各々の蹴出側エッジ３０と時刻ｔｉ のフットプリント後縁の輪郭を表す関数ｆ２ （ｘ）との交点座標を求める。図７には、この状態でのフットプリントの位置をｉ番目（時刻ｔｉ ）の位置で表してある。
【００５２】
変数ｉの値が初期値でないときはステップ１０８の詳細を示す図１０のステップ１６０の処理に進む。
【００５３】
ステップ１６０では、時刻ｔｉ からΔＴ時間経過後の時刻ｔｉ＋１ のフットプリントの位置（図７のｉ＋１番目の位置、すなわちフットプリントが単位距離ΔＤ移動した位置）を求め、ΔＴ時間経過後の踏込側エッジ２８のフットプリント前縁の輪郭との交点及び蹴出側エッジ３０とフットプリント後縁の輪郭との交点を求める。
【００５４】
次のステップ１６２では、踏込側エッジ２８の交点間の距離すなわち交差部位Ｌｉ１の長さを求めると共に、蹴出側エッジ３０の交点間の距離すなわち交差部位Ｔｉ１の長さを求める。次のステップ１６４では、交差部位Ｌｉ１の長さのフットプリント前縁の輪郭に対する投影長さＡｉ１を求めると共に、交差部位Ｔｉ１の長さのフットプリント後縁の輪郭への投影長さＢｉ１を求める。次のステップ１６６では、ステップ１６４で演算された投影長さＡｉ１、Ｂｉ１を上記（３）、（４）式に代入することにより踏込側エッジ２８上の音源及び蹴出側エッジ３０上の音源から発生する音の波形を決定する。
【００５５】
ステップ１６８では、フットプリント前縁の輪郭に沿って各踏込側エッジ２８から発生される音を以下の（７）式にしたがって積算すると共に、フットプリント後縁の輪郭に沿って各蹴出側エッジ３０から発生する音の波形を以下の（８）式にしたがって積算する。なお、下記の式ではフットプリントの前縁の輪郭に沿って発生する音、フットプリントの後縁の輪郭に沿って発生する音は同相としたが、各音源と観測点までの距離に応じた位相差を加えてもよく、位相差Φを音源毎に定めてもよい。

Figure 0003595411
この積算値ｆＬｉ、ｆＴｉはステップ１７０においてパーソナルコンピュータ１０のＲＡＭに記憶される。
【００５６】
次のステップ１１０では減衰波形Ｆｉ 、Ｋｉ 及び積算値ｆＬｉ、ｆＴｉをそれぞれＮ回演算したか否かを判断することによりタイヤ１周分の演算が終了したか否かを判断し、タイヤ１周分の演算が終了していないときはステップ１０６に戻って上記の処理を繰り返し、タイヤ１周分の演算が終了したと判断されたときには、ステップ１１２において以下の（９）式にしたがって減衰波形Ｆｉ 、Ｋｉ 及び積算値ｆＬｉ、ｆＴｉをタイヤ１周分にわたって積算することによりトレッド全面にわたる波形の総和ｆを演算する。
【００５７】
Figure 0003595411
なお、積算値ｆＬｉ、ｆＴｉをＮ回演算していないときには、ステップ１６２で交差部位Ｌｉ２、Ｌｉ３、・・・Ｌｉｋ、・・・の長さ、交差部位Ｔｉ２、Ｔｉ３、・・・Ｔｉｊ、・・・の長さを順に求め、ステップ１６４で交差部位Ｌｉ２、Ｌｉ３、・・・Ｌｉｋ、・・・の長さのフットプリント前縁の輪郭に対する投影長さＡｉ２、Ａｉ３、・・・Ａｉｋ、・・・、交差部位Ｔｉ２、Ｔｉ３、・・・Ｔｉｊ、・・・の長さのフットプリント後縁の輪郭への投影長さＢｉ２、Ｂｉ３、・・・Ｂｉｊ、・・・を順に求め、ステップ１６６で投影長さＡｉ２、Ａｉ３、・・・Ａｉｋ、・・・、Ｂｉ２、Ｂｉ３、・・・Ｂｉｊ、・・・を上記（３）、（４）式に代入することにより踏込側エッジ２８上の音源及び蹴出側エッジ３０上の音源から発生する音の波形を順に決定する。
【００５８】
ステップ１１４において上記（９）式で演算されたトレッド全面にわたる波形の総和ｆをアナログ信号に変換し、ステップ１１６においてこのアナログ信号をインタフェース１２を介して出力するとともにパーソナルコンピュータ１０のＣＲＴに表示する。ステップ１１８でタイヤデータの変更無しと判断され、かつステップ１２０でシミュレーションが終了していないと判断されたときには、このステップ１１６を繰り返してアナログ信号の出力と波形の表示とを連続して行なう。
【００５９】
アナログ信号は信号処理回路１４のローパスフィルタによって高周波（例えば、１×１０４ Ｈｚ以上）の周波数成分がカットされるとともにアンプで増幅されてヘッドホン１６から可聴音として放音される。ここで、高周波数成分をカットするローパスフィルタを用いるのは、タイヤ騒音の周波数帯域は０〜２×１０３ Ｈｚ程度であり、１×１０４ Ｈｚ以上の高周波数成分は不要であるからである。
【００６０】
ヘッドホン１６でタイヤ騒音を聴取した結果、タイヤ騒音の評価が悪い場合には、パーソナルコンピュータ１０のキーボードを操作してホストコンピュータにアクセスすることにより、トレッドパターンの変更等を行なう。また、タイヤ移動速度の相違によるタイヤ騒音の相違を聴取したいときにはタイヤ移動速度の変更、タイヤの大きさによるタイヤ騒音の変化を聴取したいときにはタイヤ周長の変更、タイヤに作用する荷重によるタイヤ騒音の変化を聴取したいときにはフットプリントの形状の変更、路面形状の変化によるタイヤ騒音の変化を聴取したいときには３次元の路面形状データの変更、２次元の路面形状データを使用した場合には路面感度係数の変更等を行なう。
【００６１】
この結果、ステップ１１８においてタイヤデータの変更有りと判断され、ステップ１００に戻って上記のステップを繰返すことにより変更されたタイヤデータに対応するタイヤ騒音の聴取が可能となる。
【００６２】
上記のタイヤ騒音シミュレータを使用して実際にシミュレーションを行った結果を図１１及び図１２に示す。図１１（３）の例は、ピッチ数５７個、モノピッチでピッチ長３５ｍｍでで定まる、正方形の負荷支持部を多数備えたトレッドパターンを図１１の（１）に示すように２２５／５０Ｒ１６の大きさのスムーズタイヤに加工し、タイヤ移動速度６０Ｋｍ／ｈで２種類の路面と路面を考慮しないときのタイヤ近傍の音をマイクロホンで実測した実験結果を示し、図１１（２）の例は、そのシュミレーション結果を示すものである。２種類の路面は、ドラム表面にセーフティーウォークを張り付けた路面振幅が細かい路面（セーフティーウォーク路）と、実際のアスファルト路面に近い路面荒さを有するドラム表面（疑似アスファルト路）でのデータである。図から理解されるように、シミュレーション結果と実験結果とはよく一致している。
【００６３】
また、図１２に上記と同様の条件での１９５／６５Ｒ１４の大きさの市販タイヤでの結果を示す。ピッチ数は５９、ピッチ比は７：８：９：１０：１１である。この場合もシミュレーション結果と実験結果とがよく一致していることが理解できる。
【００６４】
また、上記の両方のタイヤについて可聴音を発生させ、実測のタイヤ騒音と聞き比べをした結果良く対応することが確認できた。
【００６５】
上記の実施の形態では、タイヤ騒音をシミュレートする例について説明したが、式（１）〜（４）の減衰波形に代えて、ロードノイズのような車内騒音を表す波形を使用すれば、タイヤ転動時に微小突起がタイヤ接地面に入力したときに発生する車内騒音をシミュレートすることができる。
【００６６】
また、上記では路面凹凸によるタイヤ騒音及び車内騒音、及び負荷支持部によるタイヤ騒音及び車内騒音をシミュレートする例について説明したが、式（１）及び（２）のみを使用して路面凹凸によるタイヤ騒音及び車内騒音のみをシミュレートするようにしてもよい。
【００６７】
【発明の効果】
以上説明したように本発明によれば、単一の微小突起が回転中のタイヤに入力したとき及びタイヤから離れたときのタイヤ騒音の波形、または単一の微小突起が回転中のタイヤに入力したとき及びタイヤから離れたときの車内騒音の波形を基準にトレッドの路面との接触部の輪郭とタイヤパターンの影響とを考慮して合成した音を出力しているので、忠実度の非常に高いタイヤ騒音または車内騒音を発生することができる騒音シミュレート方法及びシミュレータを提供することができる、という効果が得られる。
【図面の簡単な説明】
【図１】本実施の形態のタイヤ騒音シミュレータのブロック図である。
【図２】トレッドパターンとフットプリントの形状を示す平面図である。
【図３】（１）はスムーズタイヤの路面との接触部の近傍で単一微小突起がタイヤの接地面内に入る状態を示す断面図、（２）は路面粗さを表す波形を示す線図である。
【図４】フットプリントの前後縁部を拡大して示す模式図である。
【図５】乱数列とトレッドパターンの断面とを対応して示す線図である。
【図６】タイヤの路面との接触部の近傍を示す断面図である。
【図７】フットプリントの前後縁部と負荷支持部の各エッジとの交点部分を拡大して示す模式図である。
【図８】本実施の形態のタイヤのルーチンを示す流れ図である。
【図９】図８のステップ１０６の詳細を示す流れ図である。
【図１０】図８のステップ１０８の詳細を示す流れ図である。
【図１１】（１）はトレッドパターン示す平面図、（２）は（１）のトレッドパターンが加工されたタイヤの騒音シミュレーション結果（予測値）を示す線図、（３）はこのタイヤの騒音をマイクロホンで集音した実験結果を示す線図である。
【図１２】（１）はトレッドパターン示す平面図、（２）は（１）のトレッドパターンを有する市販タイヤの騒音シミュレーション結果（予測値）を示す線図、（３）はこの市販タイヤの騒音をマイクロホンで集音した実験結果を示す線図である。
【符号の説明】
２４ 負荷支持部
２８ 踏込側エッジ
３０ 蹴出側エッジ
４０ フットプリントの前縁の輪郭
４２ フットプリントの後縁の輪郭[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a noise simulation method and a simulator, and more particularly to a noise simulation method and a noise simulator capable of generating in-vehicle noise such as tire noise and road noise with high fidelity.
[0002]
Problems to be solved by the prior art and the invention
Causes of the tire noise include a blow sound caused by a plurality of load supporting portions (blocks) provided on a tire tread, a tire vibration sound caused by unevenness of a road surface shape (road surface shape), and a tire on a ground contact surface. Slip noise due to slip is considered as a main component.
[0003]
As a technique for simulating the impact sound of a block provided on a tire tread, a technique described in Japanese Patent Application Laid-Open No. 4-148840 is known.
[0004]
However, it is known that the contribution of the tire vibration component due to the unevenness of the road surface to the tire noise is high. Therefore, in order to more faithfully simulate tire noise, it is important to consider a tire vibration component due to the unevenness of the road surface shape.
[0005]
In addition, since it is known that the change in road surface shape during vehicle running has a large audible change in vehicle interior noise, the tire shaft vibrates due to the unevenness of the road surface shape and the vibration is transmitted to the inside of the vehicle. In order to simulate road noise, which is noise generated in a vehicle, it is important to consider the tire vibration component due to the unevenness of the road surface shape.
[0006]
The present invention has been made in order to solve the above problems, the sound pressure decay waveform when a single microprojection is input to the rotating tire and when the input single microprojection separates from the tire, or Very high fidelity is achieved by synthesizing a waveform formulated based on the vehicle interior noise waveform in consideration of the contour (grounding contour) of the contact portion (footprint) of the tread with the road surface and the effect of the tire pattern. It is an object of the present invention to provide a noise simulation method and a simulator capable of generating tire noise or vehicle interior noise.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 is based on two-dimensional tread data representing treads and road surface shape data representing positions of a large number of microprojections, and a number of tires having a plurality of load supporting portions on a tread are provided. A noise simulating method for simulating noise generated when the vehicle rotates on a road surface having minute projections, the contour of a contact portion of the tread with the road surface, and the contact of the tread with the road surface of the tire when the tire rotates. The contour of the leading edge of the contact portion, where the untouched portion is the contour on the side that contacts the road surface, and the contour of the contact portion of the tread with the road surface, and the portion that is in contact with the road surface of the tire when the tire rotates are the road surface The contour of the contact portion trailing edge, which is the contour on the side away from the contact portion, is defined, and the contour of the contact portion leading edge and the contact portion trailing edge are moved in the circumferential direction of the tread so that the contour of the contact portion leading edge and the contact portion trailing edge move. Rimmed Assuming that the gusset and the tread have moved relative to each other, one of the values is composed of a binary sequence corresponding to the microprojection and represents a number sequence representing the number of the microprojections per unit length. And the contour of the leading edge of the contact portion and the contour of the trailing edge of the contact portion are set for each unit length along each of the contours of the trailing edge of the contact portion, and the contour of the leading edge of the contact portion intersects with the load support portion The total number of the one value and the roughness of the road surface at a portion where the contour of the trailing edge of the contact portion and the load supporting portion intersect with each other based on the total number of the one value and the coefficient representing the roughness of the road surface. Each of the waveforms of the sounds having an amplitude based on the expressed coefficient is determined in consideration of the phase, the determined waveform of the sound is integrated over the entire tread, and an audible sound is generated based on the integrated waveform. .
[0008]
The invention according to claim 2 is the invention according to claim 1, wherein the edge of the load support portion and a stepping-side edge that is an edge on a side that first comes into contact with a road surface when the tire rotates, and an edge of the load support portion and The tread data is represented so that the trailing edge, which is the edge that comes into contact with the road surface last when the tire rotates, can be distinguished from the trailing edge. Assuming that the contour of the leading edge of the contact part, the contour of the trailing edge of the contact part, and the tread have moved relative to each other in the direction, the part that intersects with the contour of the leading edge of the contact part in the unit time of the stepping-side edge and kicks out A sound waveform having a portion intersecting with the contour of the trailing edge of the contact portion in the unit time of the side edge is further determined in consideration of the phase, and the waveform of the determined sound and the waveform of the sound defined in claim 1 are determined. The waveform is integrated over the entire tread, It is intended to generate an audible sound on the basis of the calculated waveform.
[0009]
According to a third aspect of the present invention, a tire having a plurality of load supporting portions on a tread is provided on a road surface having a plurality of minute protrusions based on two-dimensional tread data representing a tread and road surface shape data representing positions of a large number of minute protrusions. A noise simulator that simulates noise generated when rotating on a road, wherein a contour of a contact portion of a tread with a road surface and a portion that is not in contact with the road surface of the tire when the tire rotates are in contact with the road surface. The contact portion is the contour of the leading edge of the contact portion, which is the profile of the side, and the contour of the contact portion of the tread with the road surface, and the contact portion where the portion in contact with the road surface of the tire when the tire rotates is away from the road surface. A contour determining means for defining a contour of the trailing edge; and a contour of the leading edge of the contact portion, a contour of the trailing edge of the contact portion, and a trough so that the contour of the leading edge of the contact portion and the contour of the trailing edge of the contact portion move in the circumferential direction of the tread. Assuming that the relative movement has occurred, one of the values is composed of a binary sequence corresponding to the minute protrusions, and the number sequence representing the number of the minute protrusions per unit length is represented by the outline of the contact portion front edge and the contact portion. Setting means for setting the contour of the contact portion leading edge and the contour of the contact portion trailing edge for each unit length along each of the trailing edge contours, and the contact portion leading edge contour intersects with the load support portion The total number of the one value and the roughness of the road surface at a portion where the contour of the trailing edge of the contact portion and the load supporting portion intersect with each other based on the total number of the one value and the coefficient representing the roughness of the road surface. Waveform determining means for determining each of the waveforms of the sounds having the amplitudes based on the representing coefficients in consideration of the phase, integrating means for integrating the determined sound waveforms over the entire tread, and based on the integrated waveforms. Sound generating means for generating an audible sound. That.
[0010]
According to a fourth aspect of the present invention, in the third aspect of the present invention, a step-side edge which is an edge of the load support portion and which is a side edge that first comes into contact with a road surface when the tire rotates, and an edge of the load support portion And the tread data is represented so as to be distinguishable from a kick-out edge which is the edge on the side that comes into contact with the road surface last when the tire rotates, and in the waveform setting means, the contour of the contact portion front edge and the contact portion Assuming that the contour of the leading edge of the contact portion and the contour of the trailing edge of the contact portion have moved relative to the tread so that the contour of the trailing edge moves in the circumferential direction of the tread, the leading edge of the contact portion in unit time of the stepping-side edge Further, each of the sound waveforms whose sound source is a part intersecting with the contour of the contact and a part intersecting with the contour of the trailing edge of the contacting part in the unit time of the ejection side edge is further determined in consideration of the phase. Sound waveform and sound The waveform of the sound determined in claim 1 is integrated over the tread entire surface, in the sound generating means is obtained by so as to generate an audible sound based on the integrated waveform.
[0011]
Occurs when a tire having a plurality of load supporting portions on a tread rotates on a road surface having a large number of minute projections based on two-dimensional tread data representing the tread and road surface shape data representing the positions of a large number of minute projections. When simulating tire noise or vehicle interior noise, noise due to unevenness of the road surface shape of the rotating tire occurs when the minute protrusion enters the tread and when the minute protrusion entering the tread separates from the tread I do. For this reason, according to the first and third aspects of the present invention, the contour of the contact portion (footprint) of the tread with the road surface and the portion of the tire that is not in contact with the road surface when the tire rotates are in contact with the road surface. The contour of the contact portion with the road surface of the tread and the contour of the portion that is in contact with the road surface of the tire away from the road surface when the tire rotates when the minute projection is input to the contour of the leading edge of the contact portion It is assumed that a sound is generated when the microprojection moves away from the contour of the contact portion trailing edge.
[0012]
In addition, the amplitude of the generated sound depends on the number of minute protrusions and the roughness of the road surface at the intersection of the contour of the leading edge of the contact part and the load support, and the intersection of the contour of the trailing edge of the contact part and the load support. Affected by For this reason, it is assumed that the contour of the contact portion front edge and the contour of the contact portion rear edge and the tread relatively move so that the contour of the contact portion front edge and the contour of the contact portion rear edge move in the circumferential direction of the tread. The number sequence in which one value is constituted by a binary sequence corresponding to the microprojection and represents the number of microprojections per unit length is formed along each of the contour of the leading edge of the contact portion and the contour of the trailing edge of the contact portion. The contour of the leading edge of the contact portion and the contour of the trailing edge of the contact portion are set for each unit length. Then, the amplitude based on the total number of one value and the coefficient representing the roughness of the road surface at the intersection of the contour of the leading edge of the contact portion and the load support portion, and the contour of the trailing edge of the contact portion intersect with the load support portion Each of the sound waveforms having an amplitude based on the total number of the one value in the portion and the coefficient representing the roughness of the road surface is determined in consideration of the phase, and the determined sound waveform is integrated over the entire tread, and integrated. An audible sound is generated based on the generated waveform.
[0013]
According to the first and third aspects of the present invention, when a minute projection is input to the contour of the leading edge of the contact portion and the contour of the trailing edge of the contact portion, and the inputted minute projection is the contour of the leading edge of the contact portion and the trailing edge of the contact portion. Since it is assumed that sound is generated when leaving the contour, it is possible to specify the location where tire noise is generated, and therefore to synthesize sound by taking into account the phase of the sound generated from each sound source Can be.
[0014]
Note that the contour of the leading edge of the contact portion and the contour of the trailing edge of the contact portion may be determined using data on the tire such as the tire diameter and the load acting on the tire, or may be determined by actually measuring the contour of the contact portion. Alternatively, the contour of the contact portion may be determined by optical measurement.
[0015]
In addition, the noise due to the impact of the load support portion of the rotating tire is generated when the load support portion contacts the road surface and when the load support portion contacting the road surface is separated from the road surface. According to the fourth aspect of the present invention, further, a portion that becomes a sound source of the tire noise is an edge of the load supporting portion and an edge on a side that first comes into contact with a road surface when the tire rotates, and an edge of the load supporting portion. It is assumed that there is also a kick-out edge which is the edge on the side that comes into contact with the road surface last when the tire rotates. Therefore, in the inventions according to claims 2 and 4, the tread data is represented so that the stepping-side edge and the kick-out side edge can be distinguished. Then, assuming that the contour of the contact portion front edge and the contour of the contact portion rear edge and the tread relatively move so that the contour of the contact portion front edge and the contour of the contact portion rear edge move in the circumferential direction of the tire. A portion intersecting the contour of the leading edge of the contact portion in the unit time of the stepping-side edge and a portion intersecting the contour of the trailing edge of the contact portion in the unit time of the ejection side edge are used as sound sources. Next, the waveform of the sound generated from each sound source is determined in consideration of the phase, and the determined waveform of the sound and the waveform of the sound determined in claims 1 and 3 are integrated over the entire surface of the tread.
[0016]
Also in the inventions according to claims 2 and 4, since it is assumed that there is a portion serving as a sound source at the stepping-side edge and the kicking-side edge, it is possible to specify a portion where tire noise is generated, and accordingly, a sound generated from each sound source. Can be synthesized in consideration of the phase of the sound. Then, an audible sound is generated based on the integrated waveform.
[0017]
The vibration of the sound source that generates the tire noise in each of the above inventions is transmitted from the load support portion to the sidewall through the tread rubber and attenuated, and the vibration at this time propagates in the air and is heard by the observer as tire noise. Therefore, the sound waveform is preferably determined by an attenuation waveform in consideration of the transmission characteristics of the tire sound. In the case of simulating the noise in the vehicle, the noise may be determined by a waveform representing the noise heard in the vehicle.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0019]
FIG. 1 shows a block diagram of a tire simulator according to an embodiment of the present invention. This simulator includes a personal computer 10 for performing a simulation. Headphones 16 for listening to tire noise are connected to the personal computer 10 via an interface 12, a signal processing circuit 14 including a low-pass filter and an amplifier. The personal computer 10 is connected via an adapter 18 to a host computer of a tire designing system for designing a tread pattern or the like of a tire by CAD.
[0020]
Next, the principle of the simulation of the present embodiment will be described. FIG. 2 is a plan view of a tread pattern represented on an xy plane in which the x-axis is taken in the circumferential direction of the tire and the y-axis is taken in a direction parallel to the rotation axis of the tire. Are represented by two-dimensional digital data on the xy plane shown in FIG.
[0021]
In addition, the contour 40 of the leading edge of the footprint 22, that is, the contour of the footprint and the portion of the tire that is not in contact with the road surface when the tire rotates, contacting the road surface, and the trailing edge of the footprint. The contour 42, that is, the contour of the footprint and the contour on the side where the portion of the tire that is in contact with the road surface when the tire rotates is separated from the road surface, is defined by a function f on the xy plane. 1 (X), f 2 Expressed by (x). These functions can be determined by calculating the contour of the footprint or the like.
[0022]
FIG. 3A shows a single tire having a single fine protrusion 29 near a contact portion (footprint) of a smooth tire (a tire having no block pattern) cut along a plane perpendicular to the tire rotation axis. It is sectional drawing which shows the state which input into the center part in the ground contact surface of a tire, and the state in which the single micro projection 29 which input into the center part separated from the tire. In addition, 25 shows the surface of a tire.
[0023]
Observing the time axis waveform of the sound pressure generated when the single minute protrusion 29 is input to the center portion in the ground contact surface of the tire from FIG. 3, the single minute protrusion 29 is input to the contour 40 of the front edge of the footprint. It becomes an attenuation waveform that peaks at the moment when it occurs. It should be noted that the attenuation waveform has a peak even at the moment when the single minute projection 29 separates from the contour 42 of the trailing edge of the footprint.
[0024]
Therefore, the tire noise when the vehicle is traveling on the road surface can be simulated as follows.
[0025]
First, assuming that the road surface shape is formed by randomly combining a large number of single minute protrusions, the positions of the many minute protrusions are represented two-dimensionally (on the xy plane), and the road surface roughness (each position) is determined. 3D road surface data representing the size of the microprojections in the z-direction. It is also assumed that sound is generated simultaneously from each of the plurality of microprojections located on the contour of the leading edge (or the contour of the trailing edge) of the footprint.
[0026]
FIG. 3A shows an attenuation waveform at the moment when a single microprojection is input and another single microprojection is separated, and the amplitude of this attenuation waveform is the microprojection that is input at the same time or the microprojection that is separated at the same time. It increases as the number of projections increases. Therefore, in order to represent the number of minute projections that simultaneously generate sound, the number of minute projections per unit length, that is, the density of minute projections is considered. As shown in FIG. 3 (2), the density of the minute projections is a waveform representing the road surface roughness along the contour of the leading edge (or the contour of the trailing edge) of the footprint and the positive of the root mean square of the waveform. The point of intersection with the square root (rms value) and the time derivative of this waveform can be defined by the number of positive points per unit length. Note that the density of the fine protrusions can be expressed by the actual number of single fine protrusions per unit length.
[0027]
Further, in order to represent the density of the microprojections by digital data, a binary random number sequence consisting of 1 corresponding to the microprojections and 0 corresponding to a portion other than the microprojections is used. The random number sequence is set so that the ratio of the total number of 1 to the total number corresponds to the density of the minute projections. For example, the random number sequences “11001” and “00111” each mean a density of 0.6. In the present embodiment, a random number sequence in which 0s and 1s are randomly arranged is used as the numerical sequence. However, a sequence in a predetermined order may be used. You may.
[0028]
In addition, since the minute projections input to the grooves between the load support portions do not act as a sound source because they do not vibrate the tire, the small protrusions at the intersection of the contour of the front edge of the footprint and the load support portions are not included. And the total number of 1 at the intersection of the trailing edge contour of the footprint and the load support are one value that determines the amplitude of the attenuation waveform.
[0029]
Further, since the amplitude of the attenuation waveform is affected by the amplitude of the unevenness of the road surface, that is, the road surface roughness, the road surface sensitivity coefficient is considered as a coefficient based on the road surface roughness. The road surface sensitivity coefficient can be obtained by calculation from the rigidity of the load supporting portion, the physical properties of the tread rubber, the road surface roughness, and the like. The road surface sensitivity coefficient is another value that determines the amplitude of the attenuation waveform.
[0030]
The road surface sensitivity coefficient depends on various road surfaces to be simulated, such as a road surface having a small amplitude of road surface irregularities (safety walk road) and a drum surface having a surface roughness close to the actual road surface (pseudo asphalt road). May be determined in advance. In this case, since road surface roughness data is not required as road surface shape data, two-dimensional road surface shape data representing the positions of a large number of microprojections may be used.
[0031]
As described above, since the amplitude of the attenuation waveform is affected by the density of the fine protrusions and the road surface sensitivity coefficient, the sound pressure of the contour of the front edge of the footprint having the amplitude of the product of the density of the fine protrusions and the road surface sensitivity coefficient is used. Each of the attenuation waveform and the sound pressure attenuation waveform of the contour of the trailing edge of the footprint is determined in consideration of the time delay, that is, the phase difference, and the determined waveform is synthesized over the entire tread, so that the vehicle can use the road surface. Simulate tire noise while driving.
[0032]
In order to represent the actual rolling state of the tire, the footprint 22 is moved along the x-axis in the forward direction by a unit distance ΔD according to the speed of the tire (the moving speed in the horizontal direction when the tire rolls). Move to FIG. 4 is an enlarged view showing a load support portion where the contour 40 of the leading edge of the footprint and the contour 42 of the trailing edge of the footprint intersect at time t. i At the time t when the i-th footprint moves by the unit distance ΔD. i + 1 , That is, a state in which it has moved to the (i + 1) th position. This footprint moves a unit distance ΔD in a unit time ΔT.
[0033]
Time t i A random number sequence of 1's and 0's determined from the road surface density is set over the front edge contour 40 of the front edge of the footprint for each unit length.
[0034]
In the random number sequence set in this manner, the random number 1 located on the groove 26 is not a sound source, so it is converted to 0 as shown in FIG. Is calculated. Similarly, at time t i The total number Mi of 1 is also calculated for the outline 42 of the trailing edge of the footprint.
[0035]
Then, the following attenuation waveform is determined.
F i = N i ・ P F Exp [-at] sinbt (1)
K i = M i ・ P K Exp [-ct] sin (dt-φ) (2)
However,
P F : The contour of the leading edge, that is, the road surface sensitivity coefficient of the sound at the stepped portion
P K : Trailing edge contour, that is, road surface sensitivity coefficient of sound at kick-out part
a: Attenuation coefficient of the sound of the stepped part
c: Attenuation coefficient of the sound at the kick-out part
b: Frequency of the sound at the step
d: The frequency of the sound of the kick-out part
φ: the phase difference between the sound generated from the kick-out part and the sound generated from the stepped part, N i ・ P F Is the sound pressure level (value from peak to peak, that is, twice the amplitude) of the sound waveform of the stepping portion, M i ・ P K Represents the sound pressure level of the sound waveform of the stepping portion.
[0036]
The damping coefficients a and c and the frequencies b and d are determined by the physical properties of the tread rubber and the transmission characteristics of the tire, and the phase difference φ is determined by the length of the footprint and the moving speed of the tire. Is determined by the time difference (Δt in FIG. 3) from the sound generated in the above. The attenuation coefficient, frequency and phase difference are preferably determined by experiments, for example, a = 0.24 × 10 3 , B = 1200-400t, preferably as a function of time.
[0037]
And the total number N i , M i At time t i + 1 At time t i + 2 Time t i + 3 ,... Are sequentially obtained, and the sound waveform determined by the above equations (1) and (2) is synthesized over the entire tread expressed on the xy plane, and an audible sound is generated based on the synthesized value. As a result, the waveform of the tire excitation sound due to the unevenness of the road surface shape can be determined.
[0038]
In this embodiment, the tread edge 28 and the kick-out edge 30 of the load support 24 of the tread are distinguished from each other in order to determine the waveform of the impact sound generated by the load supports provided on the tread of the tire. As much as possible, the tread pattern is represented by two-dimensional digital data on the xy plane shown in FIG. As shown in FIG. 6, the step edge 28 is the edge of the load support portion 24 and the edge that first contacts the road surface when the tire rotates, that is, the edge that first contacts the road surface. . The kick-out side edge 30 is an edge of the load support portion 24 and an edge on the side that comes into contact with the road surface last when the tire rotates, that is, an edge on the side that finally leaves the road surface. 26 is a groove.
[0039]
FIG. 7 is a plan view similar to FIG. In FIG. 7, the crossing point where the stepping-side edge 28 of the load support portion 24 intersects the contour 40 of the front edge of the footprint within the unit time ΔT is denoted by L. i1 , L i2 , L i3 , ... (In the general formula, L ik ). .. (= K) are numbers sequentially assigned in the positive direction of the y-axis to the intersections that intersect the contour of the leading edge of the footprint of the step-side edge 28. In addition, the intersection of the trailing edge contour 42 of the footprint and the intersection 42 that crosses within the unit time ΔT of the ejection side edge 30 of the load support portion 24 is defined as T. i1 , T i2 , T i3 , ... (in the general formula, T ij ). .. (= J) represent numbers sequentially assigned in the y-axis direction to intersections intersecting with the contour 42 of the trailing edge of the footprint of the ejection side edge 30. . Also, the intersection L i1 , L i2 , L i3 , ..., L ik A is the projected length of the front edge of the footprint of i1 , A i2 , A i3 , ... (In the general formula, A ik ) And the intersection T i1 , T i2 , T i3 , ..., T ij The projected length of the trailing edge of the ... i1 , B i2 , B i3 , ... (in the general formula, B ik ). Intersection L ik Is a general expression for the waveform of the sound generated from each of ik And the intersection T ij The waveform of the sound generated from each of the f ij Expressed by
f ik = A ik exp [-αt] sinβt (3)
f ij = B ij exp [−γt] sin (δt−Φ) (4)
However,
A ik : Sound pressure level of the sound waveform at the intersection of the stepping-side edge (a value from peak to peak, that is, twice the amplitude). This sound pressure level corresponds to the impact force.
[0040]
B ij : Sound pressure level of the sound waveform at the intersection of the ejection side edge
α: Attenuation coefficient of the sound at the intersection of the stepping edge
γ: Attenuation coefficient of the sound at the intersection of the ejection side edge
β: Sound frequency at the intersection of the stepping edge
δ: Sound frequency at the intersection of the ejection side edge
Φ: Phase difference between the sound generated at the intersection of the ejection side edge and the sound generated at the intersection of the stepping side edge
This sound pressure level A ik , B ij Is determined by the rigidity of the load supporting portion and the physical properties of the tread rubber, the damping coefficients α and γ and the frequencies β and δ are determined by the physical properties of the tread rubber and the transmission characteristics of the tire, and the phase difference Φ is the length of the footprint and the movement of the tire. The time difference between the sound generated at the stepping-side edge determined by the speed and the sound generated at the kick-out side edge is determined by (Δt) in FIG. Is preferable, for example, α = 3.316 × 10 3 , Β = 6.24 × 10 3 It is.
[0041]
Then, the sound waveform determined by the above equations (1) to (4) is synthesized over the entire surface of the tread expressed on the xy plane, and an audible sound is generated based on the synthesized value. The noise of the tire can be simulated in consideration of the vibration sound and the impact sounds of a plurality of load supports provided on the tire tread.
[0042]
Next, a routine of the personal computer 10 for performing tire noise simulation based on the above principle will be described with reference to FIG.
[0043]
In step 100, the variable i and the like are initialized, and in step 102, the data input from the host computer via the adapter 18 and stored in the RAM and the data input from the keyboard of the personal computer 10 are fetched. These data include the tire circumference (average radius when the tire is rolling × 2π), the tire moving speed (horizontal speed when the tire is rolling), and the pattern on the xy coordinate of the tread (stepping on the tread). Including the positions of the side edge 28 and the kick-out side edge 30), and a function y = f representing the contour of the leading edge of the footprint 22. 1 (X), a function y = f representing the contour of the trailing edge of the footprint 22 2 (X), three-dimensional road surface shape data and the like representing the road surface roughness and the position of the fine protrusions when the road surface is assumed to be randomly arranged fine protrusions. Note that the function f 1 (X), f 2 (X) may be obtained by calculation without inputting.
[0044]
In the next step 103, the number of times of sampling N is calculated according to the following equations (5) and (6).
[0045]
Tire rotation time = tire circumference / tire moving speed (5)
N = time of one rotation of tire / ΔT (6)
Note that ΔT is a sampling time, and the maximum value of frequency components included in an input signal that can be handled by the system cannot exceed half the sampling frequency (Nyquist's theorem). , And is, for example, 50 μsec.
[0046]
In the next step 106, a process for determining the waveform of the tire excitation sound due to the unevenness of the road surface shape is executed, which will be described in detail later. A process for determining the waveform of the impact sound by the unit is executed.
[0047]
Next, the details of step 106 will be described with reference to FIG. In step 140, a function y = f is obtained from the three-dimensional road surface shape data. 1 (X), function y = f 2 (X) A waveform representing the road surface roughness is obtained, and the number of points per unit length at the intersection of the waveform and the rms value and the time derivative of the waveform representing the road surface roughness is obtained for each unit length. The above-described random number sequence representing the density of each road surface is created for each road surface density at the time t i This random number sequence is allocated for each unit length on the outline 40 of the front edge of the footprint of the.
[0048]
When a constant value of road surface roughness is used, a constant random number sequence may be assigned for each unit length.
[0049]
In the next step 142, as shown in FIG. 5, the random number 1 located on the groove 26 is converted into 0 in the random number sequence.
[0050]
In step 144, the total number Ni of ones located on the contour 40 of the front edge of the footprint and the total number Mi of ones located on the contour 42 of the rear edge of the footprint are calculated, and the road surface roughness and the load support portion are calculated. The road surface sensitivity coefficient is calculated based on the rigidity of the tread rubber and the physical properties of the tread rubber. Then, in step 146, an attenuation waveform is determined according to the above equations (1) and (2).
[0051]
In the next step 148, the variable i is incremented by one, and in the next step 150, it is determined whether or not the value of the variable i is the initial value initialized in step 100. Of each stepping-side edge 28 of the section 24 and the time t i F representing the contour of the leading edge of the footprint 1 (X), and the coordinates of the intersection 30 of the load supporter 24 and the time t i F representing the contour of the trailing edge of the footprint 2 The coordinates of the intersection with (x) are obtained. FIG. 7 shows the position of the footprint in this state at the i-th position (time t i ).
[0052]
If the value of the variable i is not the initial value, the process proceeds to step 160 in FIG.
[0053]
At step 160, time t i Time t after elapse of ΔT from i + 1 (I + 1-th position in FIG. 7, that is, the position where the footprint has moved by the unit distance ΔD), and the intersection and the kicking of the foot-side edge 28 with the contour of the front edge of the footprint after the lapse of ΔT time. The intersection of the side edge 30 and the contour of the trailing edge of the footprint is determined.
[0054]
In the next step 162, the distance between the intersections of the step-side edges 28, that is, the intersection L i1 And the distance between the intersections of the ejection side edges 30, that is, the intersection T i1 Find the length of In the next step 164, the intersection L i1 Length A to the contour of the leading edge of the footprint of length A i1 At the intersection T i1 Length B of the trailing edge of the footprint on the contour i1 Ask for. In the next step 166, the projection length A calculated in step 164 i1 , B i1 Is substituted into the above equations (3) and (4) to determine the waveform of the sound generated from the sound source on the stepping-side edge 28 and the sound source on the kick-out side edge 30.
[0055]
In step 168, the sound generated from each step-side edge 28 along the contour of the front edge of the footprint is integrated according to the following equation (7), and each of the kick-out edges along the contour of the rear edge of the footprint. The waveform of the sound generated from 30 is integrated according to the following equation (8). In the following formula, the sound generated along the contour of the leading edge of the footprint and the sound generated along the contour of the trailing edge of the footprint are in phase, but the sound generated according to the distance from each sound source to the observation point A phase difference may be added, and a phase difference Φ may be determined for each sound source.
Figure 0003595411
This integrated value f Li , F Ti Is stored in the RAM of the personal computer 10 in step 170.
[0056]
In the next step 110, the attenuation waveform F i , K i And integrated value f Li , F Ti Is determined N times each time, thereby determining whether the calculation for one lap of the tire has been completed. If the calculation for one lap of the tire has not been completed, the flow returns to step 106 to return to the above-described step. When the processing is repeated and it is determined that the calculation for one rotation of the tire has been completed, in step 112, the attenuation waveform F according to the following equation (9) is obtained. i , K i And integrated value f Li , F Ti Is integrated over one rotation of the tire to calculate the sum f of the waveform over the entire tread.
[0057]
Figure 0003595411
Note that the integrated value f Li , F Ti Is not calculated N times, at step 162, the intersection L i2 , L i3 , ... L ik , Length, intersection T i2 , T i3 , ... T ij ,... Are determined in order, and at step 164, the intersection L i2 , L i3 , ... L ik ,... Projected length A to the contour of the leading edge of the footprint i2 , A i3 , ... A ik , ..., intersection T i2 , T i3 , ... T ij , ... length of footprint projected onto the contour of the trailing edge B i2 , B i3 , ... B ij ,... Are obtained in order, and in step 166, the projection length A i2 , A i3 , ... A ik , ..., B i2 , B i3 , ... B ij ,... Are substituted into the above equations (3) and (4), the sound waveforms generated from the sound source on the stepping-side edge 28 and the sound source on the ejection side edge 30 are sequentially determined.
[0058]
At step 114, the sum f of the waveforms over the entire surface of the tread calculated by the above equation (9) is converted into an analog signal. At step 116, this analog signal is output via the interface 12 and displayed on the CRT of the personal computer 10. If it is determined in step 118 that the tire data has not been changed, and if it is determined in step 120 that the simulation has not been completed, step 116 is repeated to continuously output the analog signal and display the waveform.
[0059]
The analog signal is converted to a high frequency (for example, 1 × 10 4 (Hz or more) is cut off, amplified by an amplifier, and emitted from the headphones 16 as an audible sound. Here, a low-pass filter that cuts high frequency components is used because the frequency band of tire noise is 0 to 2 × 10 3 Hz, 1 × 10 4 This is because a high frequency component of not less than Hz is unnecessary.
[0060]
When the tire noise is poorly evaluated as a result of listening to the tire noise through the headphones 16, the tread pattern is changed by operating the keyboard of the personal computer 10 to access the host computer. Also, if you want to hear the difference in tire noise due to the difference in tire movement speed, change the tire movement speed, if you want to hear the change in tire noise due to the size of the tire, change the tire circumference, and change the tire noise due to the load acting on the tire. If you want to hear the change, change the shape of the footprint. If you want to hear the change in tire noise due to the change in the road shape, change the three-dimensional road shape data. If you use the two-dimensional road shape data, change the road sensitivity coefficient. Make changes, etc.
[0061]
As a result, it is determined in step 118 that the tire data has been changed, and the process returns to step 100 and repeats the above steps, so that the tire noise corresponding to the changed tire data can be heard.
[0062]
FIGS. 11 and 12 show the results of actual simulations performed using the tire noise simulator described above. In the example of FIG. 11 (3), a tread pattern having a large number of square load supporting portions, which is determined by 57 pitches, a monopitch and a pitch length of 35 mm, has a size of 225 / 50R16 as shown in FIG. 11 (1). FIG. 11 (2) shows an experimental result obtained by actually measuring the sound near the tire with a microphone when the tire is processed into a smooth tire and the tire traveling speed is 60 km / h and two types of road surface and the road surface are not considered, and the example of FIG. It shows a simulation result. The two types of road surfaces are data on a road surface with a small road surface amplitude (safety walk road) in which a safety walk is attached to the drum surface and on a drum surface (pseudo asphalt road) having a road surface roughness close to the actual asphalt road surface. As can be understood from the figure, the simulation results and the experimental results agree well.
[0063]
FIG. 12 shows the results of a commercial tire having a size of 195 / 65R14 under the same conditions as described above. The pitch number is 59 and the pitch ratio is 7: 8: 9: 10: 11. Also in this case, it can be understood that the simulation result and the experiment result are in good agreement.
[0064]
In addition, it was confirmed that audible sound was generated for both of the above-mentioned tires, and as a result of hearing comparison with actually measured tire noise, the tires were well corresponded.
[0065]
In the above embodiment, an example in which tire noise is simulated has been described. However, if a waveform representing vehicle interior noise such as road noise is used instead of the attenuation waveforms of Expressions (1) to (4), tire It is possible to simulate in-vehicle noise generated when a minute projection enters the tire contact surface during rolling.
[0066]
In the above description, an example of simulating the tire noise and the vehicle interior noise due to the road surface unevenness, and the tire noise and the vehicle interior noise due to the load support unit has been described. Only noise and vehicle interior noise may be simulated.
[0067]
【The invention's effect】
As described above, according to the present invention, a waveform of tire noise when a single minute projection is input to a rotating tire and when the tire is separated from the tire, or a single minute projection is input to a rotating tire. The synthesized sound is output in consideration of the contour of the contact area of the tread with the road surface and the influence of the tire pattern based on the waveform of the noise in the vehicle when the vehicle is separated from the tire and when the vehicle is separated from the tire. The effect of being able to provide a noise simulation method and a simulator that can generate high tire noise or vehicle interior noise is obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram of a tire noise simulator according to the present embodiment.
FIG. 2 is a plan view showing the shapes of a tread pattern and a footprint.
FIG. 3 is a cross-sectional view showing a state in which a single minute projection enters a ground contact surface of a tire near a contact portion of a smooth tire with a road surface, and FIG. 3B is a line showing a waveform representing road surface roughness. FIG.
FIG. 4 is an enlarged schematic view showing front and rear edges of a footprint.
FIG. 5 is a diagram correspondingly showing a random number sequence and a cross section of a tread pattern.
FIG. 6 is a sectional view showing the vicinity of a contact portion of the tire with a road surface.
FIG. 7 is an enlarged schematic view showing an intersection between front and rear edges of a footprint and each edge of a load supporter.
FIG. 8 is a flowchart showing a tire routine according to the present embodiment.
FIG. 9 is a flowchart showing details of step 106 in FIG. 8;
FIG. 10 is a flowchart showing details of step 108 in FIG. 8;
11 (1) is a plan view showing a tread pattern, FIG. 11 (2) is a diagram showing a noise simulation result (predicted value) of a tire on which the tread pattern of FIG. 1 is processed, and FIG. 11 (3) is a noise of the tire. FIG. 7 is a diagram showing an experimental result of collecting sound with a microphone.
FIG. 12 (1) is a plan view showing a tread pattern, (2) is a diagram showing a noise simulation result (predicted value) of a commercial tire having the tread pattern of (1), and (3) is a noise of the commercial tire FIG. 7 is a diagram showing an experimental result of collecting sound with a microphone.
[Explanation of symbols]
24 Load support
28 Stepping edge
30 Ejection edge
40 Outline of the leading edge of the footprint
42 Outline of trailing edge of footprint

Claims (4)

トレッドを表す２次元のトレッドデータ及び多数の微小突起の位置を表す路面形状データに基づいて、トレツドに複数の負荷支持部を有するタイヤが多数の微小突起を備えた路面上を回転するときに発生する騒音をシミュレートする騒音シミュレート方法であって、
トレッドの路面との接触部の輪郭でかつタイヤが回転するときにタイヤの路面と接触していない部分が路面と接触する側の輪郭である接触部前縁の輪郭と、トレッドの路面との接触部の輪郭でかつタイヤが回転するときにタイヤの路面と接触している部分が路面から離れる側の輪郭である接触部後縁の輪郭とを定め、
接触部前縁の輪郭及び接触部後縁の輪郭がトレッドの周方向に移動するように接触部前縁の輪郭及び接触部後縁の輪郭とトレッドとが相対移動したと仮定して、一方の値が微小突起に対応する２値の列で構成されかつ単位長さ当たりの微小突起の個数を表す数列を、接触部前縁の輪郭及び接触部後縁の輪郭の各々に沿った単位長さ毎に接触部前縁の輪郭及び接触部後縁の輪郭の各々に設定し、
接触部前縁の輪郭と負荷支持部とが交わった部分における前記一方の値の総数と路面の粗さを表す係数とに基づいた振幅及び接触部後縁の輪郭と負荷支持部とが交わった部分における前記一方の値の総数と路面の粗さを表す係数とに基づいた振幅を有する音の波形の各々を位相を考慮して定め、
定められた音の波形をトレッド全面にわたって積算し、
積算された波形に基づいて可聴音を発生させる騒音シミュレート方法。Occurs when a tire having a plurality of load supporting portions on a tread rotates on a road surface having a large number of minute projections, based on two-dimensional tread data representing the tread and road surface shape data representing the positions of a large number of minute projections. A noise simulation method for simulating noise
The contour of the leading edge of the contact portion, which is the contour of the contact portion of the tread with the road surface and the portion of the tire that is not in contact with the road surface when the tire rotates, that is, the contact surface with the road surface, and the contact of the tread with the road surface The contour of the part and the part in contact with the road surface of the tire when the tire rotates is defined as the contour of the contact portion trailing edge that is the contour on the side away from the road surface,
Assuming that the contour of the leading edge of the contact portion and the contour of the trailing edge of the contact portion move relative to the tread such that the contour of the leading edge of the contact portion and the contour of the trailing edge of the contact portion move in the circumferential direction of the tread, A sequence of values consisting of a binary sequence corresponding to the microprojections and representing the number of microprojections per unit length is represented by a unit length along each of the contour of the leading edge of the contact portion and the contour of the trailing edge of the contact portion. For each of the outline of the contact part front edge and the outline of the contact part rear edge,
The amplitude based on the total number of the one value and the coefficient representing the roughness of the road surface at the portion where the contour of the contact portion front edge and the load support portion intersect, and the profile of the contact portion rear edge intersects with the load support portion Determine each of the sound waveforms having an amplitude based on the total number of the one value in the portion and a coefficient representing the roughness of the road surface in consideration of the phase,
The specified sound waveform is integrated over the entire tread,
A noise simulation method for generating an audible sound based on an integrated waveform. 負荷支持部のエッジでかつタイヤが回転するときに最初に路面と接触する側のエッジである踏込側エッジと、負荷支持部のエッジでかつタイヤが回転するときに最後に路面と接触する側のエッジである蹴出側エッジとが区別できるように前記トレッドデータを表し、
接触部前縁の輪郭及び接触部後縁の輪郭がトレッドの周方向に移動するように接触部前縁の輪郭及び接触部後縁の輪郭とトレッドとが相対移動したと仮定して、踏込側エッジの単位時間に接触部前縁の輪郭と交わる部分と蹴出側エッジの単位時間に接触部後縁の輪郭と交わる部分とを音源とする音の波形の各々を位相を考慮して更に定め、定められた音の波形及び請求項１で定められた音の波形をトレッド全面にわたって積算し、積算された波形に基づいて可聴音を発生させる請求項１の騒音シミュレート方法。The stepping side edge, which is the edge of the load support portion and the edge that first comes into contact with the road surface when the tire rotates, and the stepping edge that is the edge of the load support portion that last contacts the road surface when the tire rotates. Representing the tread data so that it can be distinguished from the ejection side edge which is an edge,
Assuming that the contour of the leading edge of the contact portion and the contour of the trailing edge of the contact portion and the tread relatively move so that the contour of the leading edge of the contact portion and the contour of the trailing edge of the contact portion move in the circumferential direction of the tread, the stepping side Further determine the waveform of each of the sound sources having a portion intersecting with the contour of the leading edge of the contact portion in the unit time of the edge and a portion intersecting with the contour of the trailing edge in the unit time of the ejection side edge in consideration of the phase. 2. The noise simulating method according to claim 1, wherein the determined sound waveform and the determined sound waveform are integrated over the entire surface of the tread, and an audible sound is generated based on the integrated waveform. トレッドを表す２次元のトレッドデータ及び多数の微小突起の位置を表す路面形状データに基づいて、トレツドに複数の負荷支持部を有するタイヤが多数の微小突起を備えた路面上を回転するときに発生する騒音をシミュレートする騒音シミュレータであって、
トレッドの路面との接触部の輪郭でかつタイヤが回転するときにタイヤの路面と接触していない部分が路面と接触する側の輪郭である接触部前縁の輪郭と、トレッドの路面との接触部の輪郭でかつタイヤが回転するときにタイヤの路面と接触している部分が路面から離れる側の輪郭である接触部後縁の輪郭とを定める輪郭決定手段と、
接触部前縁の輪郭及び接触部後縁の輪郭がトレッドの周方向に移動するように接触部前縁の輪郭及び接触部後縁の輪郭とトレッドとが相対移動したと仮定して、一方の値が微小突起に対応する２値の列で構成されかつ単位長さ当たりの微小突起の個数を表す数列を、接触部前縁の輪郭及び接触部後縁の輪郭の各々に沿った単位長さ毎に接触部前縁の輪郭及び接触部後縁の輪郭の各々に設定する設定手段と、
接触部前縁の輪郭と負荷支持部とが交わった部分における前記一方の値の総数と路面の粗さを表す係数とに基づいた振幅及び接触部後縁の輪郭と負荷支持部とが交わった部分における前記一方の値の総数と路面の粗さを表す係数とに基づいた振幅を有する音の波形の各々を位相を考慮して決定する波形決定手段と、
決定された音の波形をトレッド全面にわたって積算する積算手段と、
積算された波形に基づいて可聴音を発生させる音発生手段と、
を備えた騒音シミュレータ。Occurs when a tire having a plurality of load supporting portions on a tread rotates on a road surface having a large number of minute projections based on two-dimensional tread data representing the tread and road surface shape data representing the positions of a large number of minute projections. A noise simulator that simulates noise
The contour of the tread's contact surface with the contour of the contact portion with the road surface and the contour of the side that does not contact the road surface of the tire when the tire rotates, which is the profile that contacts the road surface, and the contact of the tread with the road surface A contour determining means that defines a contour of a portion and a contour of a contact portion trailing edge that is a contour on a side away from the road surface in contact with the road surface of the tire when the tire rotates,
Assuming that the contour of the leading edge of the contact portion and the contour of the trailing edge of the contact portion and the tread relatively move so that the contour of the leading edge of the contact portion and the contour of the trailing edge of the contact portion move in the circumferential direction of the tread, A sequence of values consisting of a binary sequence corresponding to the microprojections and representing the number of microprojections per unit length is represented by a unit length along each of the contour of the leading edge of the contact portion and the contour of the trailing edge of the contact portion. Setting means for setting each of the contour of the contact portion leading edge and the contour of the contact portion trailing edge,
The amplitude based on the total number of the one value and the coefficient representing the roughness of the road surface at the portion where the contour of the contact portion front edge and the load support portion intersect, and the profile of the contact portion rear edge intersects with the load support portion Waveform determining means for determining each of the waveforms of sounds having an amplitude based on the total number of the one value in the portion and a coefficient representing the roughness of the road surface in consideration of the phase,
An integrating means for integrating the determined sound waveform over the entire tread;
Sound generating means for generating an audible sound based on the integrated waveform;
A noise simulator equipped with. 負荷支持部のエッジでかつタイヤが回転するときに最初に路面と接触する側のエッジである踏込側エッジと、負荷支持部のエッジでかつタイヤが回転するときに最後に路面と接触する側のエッジである蹴出側エッジとが区別できるように前記トレッドデータを表し、
前記波形設定手段において、接触部前縁の輪郭及び接触部後縁の輪郭がトレッドの周方向に移動するように接触部前縁の輪郭及び接触部後縁の輪郭とトレッドとが相対移動したと仮定して、踏込側エッジの単位時間に接触部前縁の輪郭と交わる部分と蹴出側エッジの単位時間に接触部後縁の輪郭と交わる部分とを音源とする音の波形の各々を位相を考慮して更に決定し、
前記積算手段において、決定された音の波形及び請求項１で決定された音の波形をトレッド全面にわたって積算し、
前記音発生手段において、積算された波形に基づいて可聴音を発生させる
請求項３の騒音シミュレータ。The stepping side edge, which is the edge of the load support portion and the edge that first comes into contact with the road surface when the tire rotates, and the stepping edge that is the edge of the load support portion that last contacts the road surface when the tire rotates. Representing the tread data so that it can be distinguished from the ejection side edge which is an edge,
In the waveform setting means, the contour of the contact portion front edge and the contour of the contact portion rear edge and the tread relatively move such that the contour of the contact portion front edge and the contour of the contact portion rear edge move in the circumferential direction of the tread. Assuming that the phase of each of the sound waveforms whose sound source is the part that intersects with the contour of the leading edge of the contact part in the unit time of the stepping-side edge and the part that intersects with the contour of the trailing edge of the contact part in the unit time of the ejection side edge Is determined in consideration of
In the integrating means, the determined sound waveform and the sound waveform determined in claim 1 are integrated over the entire tread,
4. The noise simulator according to claim 3, wherein said sound generating means generates an audible sound based on the integrated waveform.
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