JP3591133B2 - Engine speed control device - Google Patents

Description

であると予測するわけである。
【００６０】
所定時間Ｔ０は補助空気弁２０をステップ的に開いたときに吸気管内圧力が立上がってくるまでの動的遅れ時間とする。たとえば補助空気弁２０の開操作のタイミングより補助空気弁２０の開操作前の吸気管内圧力と開操作後の吸気管内圧力とを９：１に内分する圧力に達するまでの時間（たとえば８００ｍｓ）である。
【００６１】
供給空気量の補正は、空気量の増加から吸気管内圧力の増加までの動的遅れを見越して行わなければならないので、補正開始のタイミングは、エンジン回転数がアイドル回転数まで降下したタイミングよりもその動的遅れ時間の分だけ早い必要がある。補正開始のタイミングを決定するには、エンジン回転数がアイドル回転数まで降下するタイミングを予測し、その予測タイミングより上記の動的遅れ時間の前であるかどうかを逐次判定する必要があるわけである。このように、アイドル回転数までの到達予測時間を逐次求め、その値が上記の動的遅れ時間より短くなったときに補正を開始する。
【００６２】
また、図５には示していないが、補正終了のタイミングはアイドル回転数フィードバック制御の制御開始回転数ＮＳＴＡＲＴ（＝ＮＥＴＡＲＧＥＴ＋２５）［ｒｐｍ］である。補正終了のタイミングをＮＳＴＡＲＴとしたのは、本発明の補正制御とアイドル回転数フィードバック制御との干渉を回避するためである。
【００６３】
このようにして、供給空気量の補正を行うかどうかの判定を行ったら、図２のステップ５に戻り、アイドル状態への移行時の供給空気量ＱＡＬＬを演算する。この演算方法については図６により説明する。図６のジョブは１０ｍｓジョブである。
【００６４】
ステップ５１、５２ではフラグＦＰＬＵＳの今回と前回の状態をみて、今回はＦＰＬＵＳ＝１かつ前回はＦＰＬＵＳ＝０のとき（フラグＦＰＬＵＳの“０”から“１”への切換時）にはステップ５３に進み、コレクタ４に設けた圧力センサ２１（図２参照）により得られる吸気管内圧力Ｐを初期値Ｂｉｎｉｔに入れる。今回、前回ともＦＰＬＵＳ＝１のときにはステップ５３を飛ばしてステップ５４に進み、
Ｂｏｏｓｔ ｓｔａｔｉｃ（ｔ）
＝｛Ｇｍ（ｚ）／Ｇ（ｚ）｝×（ＢＩＤＬＥ−Ｂｉｎｉｔ）＋Ｂｉｎｉｔ…（４）
ただし、Ｇｍ（ｚ）：規範モデル特性
Ｇ（ｚ）：一次遅れ特性
の式により平衡吸気管内圧力Ｂｏｏｓｔ ｓｔａｔｉｃ（ｔ）を演算し、このＢｏｏｓｔ ｓｔａｔｉｃ（ｔ）とエンジン回転数ＮＥからステップ５５において所定のマップＭＡＰ Ｑを検索して供給空気量ＱＡＬＬを求める。なお、ＱＡＬＬは０からの値である。
【００６５】
ここで、Ｂｏｏｓｔ ｓｔａｔｉｃ（ｔ）は実際の吸気管内圧力Ｂｏｏｓｔ（ｔ）が規範出力Ｂｏｏｓｔ ｍ（ｔ）（後述する）と一致するような平衡吸気管内圧力、ＱＡＬＬは現在の回転数において平衡吸気管内圧力がＢｏｏｓｔ ｓｔａｔｉｃ（ｔ）となるような供給空気量である。
【００６６】
上記の供給空気量ＱＡＬＬは、動的エンジンモデルを用いて規範モデルに追従させる制御方式により求めたものである。
【００６７】
ここで、動的エンジンモデルは、供給空気量を操作したとき吸気管内圧力がどのように時間的に変化するのかを記述した差分方程式（言い換えればディジタルフィルタ）である。動的エンジンモデルによれば、供給空気量を操作したときに吸気管内圧力がどのように時間的に変化するのかが分かっているのであるから、逆に所定の時間後に所定の吸気管内圧力にしたいときにどのように供給空気量を操作すればよいのかも分かるわけである。この原理を用いてエンジン回転数がアイドル回転数まで降下してきたときにアイドル時の要求吸気管内圧力ＢＩＤＬＥとなるように供給空気量ＱＡＬＬを調整するのである。
【００６８】
規範モデルに追従させる制御方式については公知であるため図７、図８を参照しながら以下に簡単に説明する。いま、図７に示したように、回転数ＮＥおよび供給空気量ＱＡＬＬを入力としその入力時の平衡吸気管内圧力Ｂｏｏｓｔ ｓｔａｔｉｃを出力とするマップＭＡＰ Ｂｏｏｓｔと、平衡吸気管内圧力Ｂｏｏｓｔ ｓｔａｔｉｃより実際の吸気管内圧力Ｂｏｏｓｔへの遅れ特性を一次遅れで近似した特性Ｇ（ｚ）とを直列に接続した動的エンジンモデルを仮想的に考える。
【００６９】
平衡吸気管内圧力Ｂｏｏｓｔ ｓｔａｔｉｃ、実際の吸気管内圧力Ｂｏｏｓｔとも時間ｔの関数であるため、Ｂｏｏｓｔ ｓｔａｔｉｃ（ｔ）、Ｂｏｏｓｔ（ｔ）と表すと、
Ｂｏｏｓｔ（ｔ）＝Ｇ（ｚ）×Ｂｏｏｓｔ ｓｔａｔｉｃ（ｔ） …（５）
である。
【００７０】
（５）式の応答特性Ｇ（ｚ）は、たとえば
Ｇ（ｚ）＝（１＋ａ１）ｚ^−１／（１＋ａ１×ｚ^−１） …（６）
ただし、ａ１：係数
であり（Ｇ（１）＝１）、具体的にはディジタル一次ローパスフィルタにより構成することができる（図７参照）。
【００７１】
ここで、（６）式の係数ａ１は、補助空気弁２０をステップ的に開操作してから吸気管内圧力が遅れて立ち上がるまでの応答特性により定める。
【００７２】
また、フラグＦＰＬＵＳの“０”より“１”への切換時の吸気管内圧力の望ましい応答特性（規範モデル特性Ｇｍ（ｚ））を、フラグＦＰＬＵＳの“０”より“１”への切換タイミングから少なくとも所定時間Ｔ０のあとに吸気管内圧力がアイドル時の要求吸気管内圧力ＢＩＤＬＥの近傍となるように、たとえば
Ｇｍ（ｚ）＝（１＋ｃ１）ｚ^−２／（１＋ｃ１×ｚ^−１） …（７）
ただし、ｃ１：規範モデルの特性を定める係数
の式により設定する（Ｇｍ（１）＝１）。このとき、ＦＰＬＵＳが“０”より“１”に切換わった（この切換タイミングでｔ＝０とおく）後は、切換わる直前での吸気管内圧力を初期値Ｂｉｎｉｔとし、ＢＩＤＬＥを最終的に収束する値として、

の式により過渡的な吸気管内圧力（規範出力Ｂｏｏｓｔ ｍ（ｔ））を与えることができる（図８の第２段目参照）。
【００７３】
実際の吸気管内圧力Ｂｏｏｓｔ（ｔ）を上記（８）式の規範出力Ｂｏｏｓｔ ｍ（ｔ）と一致させるには、
Ｇ（ｚ）×Ｂｏｏｓｔ ｓｔａｔｉｃ（ｔ）＝Ｂｏｏｓｔ ｍ（ｔ）
の式が成立しなければならないので、この式をＢｏｏｓｔ ｓｔａｔｉｃ（ｔ）について整理する。
【００７４】
Ｂｏｏｓｔ ｓｔａｔｉｃ（ｔ）＝Ｂｏｏｓｔ ｍ（ｔ）／Ｇ（ｚ）
この式の右辺に（８）式を代入すると、

となり、上記（４）式が得られる。
【００７５】
このようにして、アイドル回転数のフィードバック制御における制御開始回転数ＮＳＴＡＲＴにエンジン回転数が達するときの吸気管内圧力が要求吸気管内圧力ＢＩＤＬＥと一致するように供給空気量ＱＡＬＬを演算することができるのである（図８の第４段目参照）。
【００７６】
なお、上記（４）式の｛Ｇｍ（ｚ）／Ｇ（ｚ）｝部分の計算は、一般的に知られているディジタル演算であるため、説明は省略する。
【００７７】
こうして供給空気量ＱＡＬＬを算出したら、図２のステップ６に戻り、ＱＡＬＬ−ＱＬＥＡＫに応じて補助空気弁２０に与えるＯＮデューティを求め、これをステップ７において補助空気弁制御用の出力レジスタに転送する。この転送後にＯＮデューティがＰＷＭ信号に変換されて補助空気弁２０に出力され、補助空気弁２０を流れる空気量がＱＡＬＬ−ＱＬＥＡＫとなるようにＰＷＭ制御される。ＯＮデューティ（つまり補助空気弁開度）は、補助空気弁２０以外からエンジンに供給される空気流量（スロットル弁３からの漏れ空気流量等）の総和をＱＬＥＡＫとしたとき、補助空気弁部の空気流量がＱＡＬＬ−ＱＬＥＡＫである開度となるように定めているわけである。ＱＬＥＡＫは実験的に計測しておく。
【００７８】
ここで、本実施形態の作用を説明する。
【００７９】
供給空気量を増加させてから吸気管内圧力（エンジントルク相当）が立ち上がるまでの動的な遅れが十分には考慮されていなかった従来例に対し、本実施形態では、供給空気量を操作したときに吸気管内圧力がどのように時間的に変化するのかを記述した動的エンジンモデルを備え、スロットル弁が全閉位置かつエンジン回転数の降下率が所定値以上かつアイドル回転数に到達するまでの予測時間が所定の時間Ｔ０以内となったときを補正開始のタイミングとして、目標回転数ＮＥＴＡＲＧＥＴ、冷却水温ＴＷおよびエンジンにより駆動される補機負荷の作動状態に応じてアイドル時の要求吸気管内圧力ＢＩＤＬＥを演算し、エンジン回転数がアイドル回転数に達するときの吸気管内圧力がこの要求吸気管内圧力ＢＩＤＬＥと一致するように上記の動的エンジンモデルを用いて規範モデルに追従させる制御方式により供給空気量ＱＡＬＬを演算し、この供給空気量ＱＡＬＬが流れるように補助空気弁２０を制御するので、供給空気量の操作から吸気管内圧力の上昇までの動的遅れを見越して供給空気量を操作することが可能となり、アイドル状態への移行時にエンジン回転数がどのように降下するときでも（たとえば図９のように急降下するときや図１０のようにゆっくと降下するときでも）、回転数を落ち込ませることなく回転数を目標回転数に速やかに収束させることができる。
【００８０】
また、回転数が目標回転数に達したときの吸気管内圧力が、目標回転数、冷却水温あるいはエンジンにより駆動される補機負荷の作動状態に見合ったアイドル時の要求吸気管内圧力の近傍となるようにしていない従来例では、たとえば補機負荷が小さいとき供給空気量が過剰ぎみとなってエンジン回転数が一時的に吹き上がり、また補機負荷が大きいとき供給空気量が不足ぎみになって回転数の落ち込みが生じることがあり、運転フィーリングが悪くなるのであるが、本実施形態では、目標回転数ＮＥＴＡＲＧＥＴ、冷却水温ＴＷおよび補機負荷の作動状態に応じてアイドル時の要求吸気管内圧力ＢＩＤＬＥを演算することから、上記のように補機負荷が小さいときこれに合わせて供給空気量が少なくなって供給空気量の過剰による回転数の一時的な吹き上がりが防止され、また補機負荷が大きいときこれに合わせて供給空気量が多くなり、供給空気量の不足による回転数の落ち込みが防止され、これによって運転フィーリングが悪くなることがないのである。
【００８１】
図１１のフローチャートは第２実施形態で、第１実施形態の図６に対応する。図６と同一の部分には同一のステップ番号をつけている。第１実施形態の図２、図３、図４、図５のフローチャートは第２実施形態でも使う。
【００８２】
また、図１２、図１３、図１４のフローチャートは第３実施形態、図１２、図１３、図１５のフローチャートは第４実施形態で、図１２は第１実施形態の図２に、図１３は図４に、図１４、図１５は図６に対応する。対応する各図と同一の部分には同一のステップ番号をつけている。なお、図３と図５は第３、第４の各実施形態でも使用する。
【００８３】
第１実施形態はエンジントルク相当量として吸気管内圧力を用いたものであったが、第３、第４の各実施形態はエンジントルク相当量として空気量を用いたものである。詳細には、図１３のフローチャート（図１２ステップ７１の詳細）はアイドル時の要求空気流量ＱＩＤＬＥ［リットル／ｍｉｎ］を算出するためのものである。ステップ８１で目標回転数ＮＥＴＡＲＧＥＴと冷却水温ＴＷから所定のマップＭＡＰ Ｑ２を検索してアイドル時の要求空気流量の基本値Ｑ１を求め、ＡＣＳＷ＝１（エアコンの作動状態）にあるときには、ステップ２２よりステップ８２に進んでメモリＱ２に所定値ＱＡＣ（たとえば５０リットル／ｍｉｎ）を、またＡＣＳＷ＝０のときはステップ８３に進んで０を入れ、ステップ８４においてこのメモリＣ２の値を上記の基本値Ｑ１に加えた値をＱＩＤＬＥとして求める。Ｑ１はエンジンの無負荷状態においてアイドル回転数を目標回転数に維持するために要求される空気流量であり、エアコン作動時にはエアコン負荷がエンジンに作用する分だけアイドル回転数が低下するので、エアコン作動時にＢＡＣの分だけ空気流量を多くするのである。図８の第４段目にＱＩＤＬＥを示す。なお、ステップ８１のＱ_ＡＦＭはエアフローメータ出力より得られる吸入空気流量である。
【００８４】
さて、第２、第３、第４の各実施形態は、動的エンジンモデルを使わないものの、エンジン回転数がアイドル回転数まで降下してくる前に動的遅れ（つまり供給空気量を操作したときに吸気管内圧力が立ち上がる（たとえば９０％立ち上がり）までの遅れ）を見越して予め空気量を増量することで動的遅れに対する補償を行うようにしたものである。
【００８５】
具体的には、第２実施形態は、図１１に示したように、ＦＰＬＵＳ＝１のときステップ６１に進んでアイドル時の要求吸気管内圧力ＢＩＤＬＥとエンジン回転数ＮＥから所定のマップＭＡＰ Ｑ３を検索した値を供給空気量ＱＡＬＬとして求める。このときの供給空気量ＱＡＬＬ（ＱＡＬＬ＞ＱＩＤＬＥ）は、現在の回転数でアイドル時の要求吸気管内圧力ＢＩＤＬＥを定常的に保つために必要な供給空気量である。同様にして、第３実施形態は、図１４に示したように、ＦＰＬＵＳ＝１のときステップ９１に進んでアイドル時の要求空気流量ＱＩＤＬＥとエンジン回転数ＮＥから所定のマップＭＡＰ Ｑ４を検索した値を供給空気量ＱＡＬＬとして求める。このときの供給空気量ＱＡＬＬ（ＱＡＬＬ＞ＱＩＤＬＥ）は、現在の回転数でアイドル時の要求空気流量ＱＩＤＬＥを定常的に保つために必要な供給空気量である。マップＭＡＰ Ｑ３とＭＡＰ Ｑ４は実験的に求めておく。
【００８６】
これに対して第４実施形態は、図１５に示したように、ＦＰＬＵＳ＝１のときステップ１０１に進み、
ＱＡＬＬ＝（ＮＥ／ＮＥＴＡＲＧＥＴ）×ＱＩＤＬＥ …（１１）
の式により供給空気量ＱＡＬＬを求める。このときの供給空気量ＱＡＬＬ（ＱＡＬＬ＞ＱＩＤＬＥ）は、現在の回転数における一燃焼当たりのシリンダ内空気量［リットル／ｃｙｌ］とアイドル時における一燃焼当たりの要求シリンダ内空気量［リットル／ｃｙｌ］とを定常的に一致させるに必要な空気量である。
【００８７】
ここで、アイドル時における一燃焼（一吸気）当たりの要求シリンダ内空気量［リットル／ｃｙｌ］というのは、たとえば、アイドル回転数を１０００［ｒｐｍ］、アイドル時の要求空気流量ＱＩＤＬＥを１００［リットル／ｍｉｎ］としたとき、４気筒エンジンであればアイドル時に吸気（燃焼）が１０００×２［回／ｍｉｎ］あるので、１００／（１０００×２）［リットル／ｃｙｌ］といった値である。
【００８８】
第２、第３、第４の各実施形態では、動的エンジンモデルを使わないため、第１、第２の各実施形態のように緻密な制御はできないものの、第１実施形態と同様の作用効果が生じることに変わりない。第２、第３、第４の各実施形態ではまた、動的エンジンモデルがよく分からないときでも実現可能であり、ディジタルフィルタ演算が不要であるため演算量が少なくて済む。第４実施形態ではさらにＲＯＭ内にマップをもつ必要がないというメリットもある。
【００８９】
図１６のフローチャートは第５実施形態で、第１実施形態の図５に対応する。図５と同一の部分には同一のステップ番号をつけている。図２、図３、図４、図６のフローチャートは第５実施形態でも使う。
【００９０】
この実施形態は、ステップ１１１において上記の到達予測時間Ｔｒｅａｃｈにバックラッシュ特性処理（フィルタリング処理）を施し、このバックラッシュ特性処理後のＴｒｅａｃｈと所定時間Ｔ０をステップ１１２において比較するようにしたものである。
【００９１】
クランク角センサ１５からの信号に基づいて検出されるエンジン回転数ＮＥにはクランク角センサ１５の加工誤差等に起因したノイズを含んでいるため、エンジン回転数ＮＥに基づいて算出される上記の到達予測時間Ｔｒｅａｃｈがノイズの影響を受け、図１７に示したように真値の近傍でゆらぎ、特にＴｒｅａｃｈが所定時間Ｔ０の近傍でゆらいだときには、供給空気量の補正判定出力に不要なチャタリングが生じてしまうことになるが、第５実施形態により到達予測時間Ｔｒｅａｃｈにバックラッシュ特性処理を施した後の値はゆらぎのない値となることから、Ｔｒｅａｃｈが所定時間Ｔ０の近傍でゆらぐことに起因して生じる不要なチャタリングを防止することができる。
【００９２】
ここで、バックラッシュ処理を簡単に説明しておくと、バックラッシュ処理は、図１８に示したように、球Ａを所定長さの筐体Ｂに入れて球Ａを左右に動かしたときの筐体Ｂの位置で表されるもので（つまりＣ、Ｄの過程では球Ａが動いても筐体Ｂは動かない）、バックラッシュの入力が球Ａの座標、出力が筐体Ｂの座標に対応する。したがって、横軸に時間をとったときの入出力関係はたとえば図１９のようになり、筐体Ｂの左右方向幅によりバックラッシュ幅が定まる。
【００９３】
なお、バックラッシュ処理に代えて平均化処理を施すことでも、回転数の検出誤差の影響等を軽減することができる。
【００９４】
実施形態では説明しなかったが、アイドル回転数のフィードバック制御における制御開始回転数ＮＳＴＡＲＴに回転数が到達したときの（あるいは到達する直前における）吸気管内圧力（あるいはその推定値）がアイドル時の要求吸気管内圧力ＢＩＤＬＥより低いときには点火時期をさらに進角させる（発生トルクを増加させる）ことで、回転数の落ち込みの回避を確実にし、また制御開始回転数ＮＳＴＡＲＴに回転数が到達したときの吸気管内圧力がＢＩＤＬＥより高いときにはさらに点火時期を遅角させる（発生トルクを減少させる）ことで、回転数の吹き上がりの回避を確実にすることができる。
【００９５】
上記の到達予測時間Ｔｒｅａｃｈの演算方法は実施形態に示したものに限られず、スプライン補間等の外挿方法を用いて演算してもよい。また、補機はエアコンに限らず、たとえばパワステの場合にも本発明を適用することができる。
【００９６】
実施形態では、空気量を供給する手段が補助空気弁である場合で説明したが、これに限られるものでない。たとえば、補助空気を燃料噴射弁の噴孔の近くに導き、この補助空気に噴射燃料を衝突させることによって噴射燃料の微粒化を促進するようにした、いわゆるエアアシストインジェクタ（インジェクタ一体型）を吸気バルブの近傍に取り付けたものがあり、このものではエアアシストインジェクタへの補助空気量を増加させることによって供給空気量を増加させることができる。このときには、補助空気量の操作から吸気管内圧力が上昇するまでの動的遅れ時間が図１の場合より短くなるという相違はあるものの、同様に本発明を適用することができる。
【００９７】
また、空気量供給手段に代えて、ＳＰＩ、ＭＰＩいずれの燃料量供給手段を用いてもかまわない。この場合には、以下の置き換えを行うだけで同様に説明することができる。
【００９８】
▲１▼供給空気量ＱＡＬＬ →一燃焼当たりの供給燃料量
▲２▼吸気管内圧力または空気流量 →一燃焼当たりのシリンダ内吸入燃料量
▲３▼ＢＩＤＬＥまたはＱＩＤＬＥ →アイドル時の一燃焼当たりの要求燃料量
▲４▼補助空気弁開度 →燃料噴射弁の開時間
【００９９】
【発明の効果】
供給空気量を増加させてから吸気管内圧力が立ち上がるまでの動的な遅れが十分には考慮されていなかった従来例に対し、第１の発明では、供給空気量の補正を開始すると判定したとき供給空気量およびエンジントルクを入出力とする動的エンジンモデルを用いて規範モデルに追従させる制御方式によりエンジン回転数がアイドル回転数に達したときのエンジントルクがアイドル時の要求エンジントルクと一致するように供給空気量を演算し、この供給空気量をエンジンに供給するので、供給空気量の操作からエンジントルクの上昇までの動的遅れを見越して供給空気量を操作することが可能となり、アイドル状態への移行時にエンジン回転数がどのように降下するときでも、回転数を落ち込ませることなく回転数を目標回転数に速やかに収束させることができる。
【０１００】
第８の発明では、一燃焼当たりの供給燃料量の補正を開始すると判定したとき一燃焼当たりの供給燃料量およびエンジントルクを入出力とする動的エンジンモデルを用いて規範モデルに追従させる制御方式によりエンジン回転数がアイドル回転数に達したときのエンジントルクがアイドル時の要求エンジントルクと一致するように一燃焼当たりの供給燃料量を演算し、この一燃焼当たりの供給燃料量をエンジンに供給するので、一燃焼当たりの供給燃料量の操作からエンジントルクの上昇までの動的遅れを見越して一燃焼当たりの供給燃料量を操作することが可能となり、アイドル状態への移行時にエンジン回転数がどのように降下するときでも、回転数を落ち込ませることなく回転数を目標回転数に速やかに収束させることができる。加えて第８の発明では、リーンバーンシステムにおいて供給空気量を調整する手段を備えない場合であっても、一燃焼当たりの供給燃料量の操作からエンジントルクの上昇までの動的な遅れを見越して一燃焼当たりの供給燃料量を増量することが可能となり、回転数の落ち込みを回避しつつ回転数をアイドリング回転数に速やかに収束させることができる。
【０１０１】
第２、第３の各発明では、動的エンジンモデルを使わないものの、エンジン回転数がアイドル回転数まで降下してくる前に動的遅れを見越して予め空気量を増量するので、供給空気量の操作からエンジントルクが立ち上がるまでの動的遅れに対する補償を行うことができる。第９、第１０の各発明では、動的エンジンモデルを使わないものの、エンジン回転数がアイドル回転数まで降下してくる前に動的遅れを見越して予め一燃焼当たりの燃料量を増量するので、一燃焼当たりの供給燃料量の操作からエンジントルクが立ち上がるまでの動的遅れに対する補償を行うことができる。
【０１０２】
第２、第３、第９、第１０の各発明ではまた、動的エンジンモデルがよく分からないときでも実現可能であり、ディジタルフィルタ演算が不要であるため演算量が少なくて済む。第３、第１０の各発明ではさらにＲＯＭ内にマップをもつ必要がないというメリットもある。
さらに第１、第２、第３の各発明ではスロットル弁が全閉位置かつエンジン回転数の降下率が所定値以上かつその降下率がそのまま継続すると仮定してアイドル回転数に到達するまでの時間を予測し、この到達予測時間が所定時間以内となったとき供給空気量の補正を開始すると判定し、また第８、第９、第１０の各発明ではスロットル弁が全閉位置かつエンジン回転数の降下率が所定値以上かつその降下率がそのまま継続すると仮定してアイドル回転数に到達するまでの時間を予測し、この到達予測時間が所定時間以内となったとき一燃焼当たりの供給燃料量の補正を開始すると判定するので、エンジン回転数がアイドル回転数に達したときのエンジントルクを、追従性よくアイドル時の要求エンジントルクに近づけることができる。
【０１０３】
第４と第１１の各発明ではアイドル時にエンジンに作用する補機負荷量、アイドル時の目標回転数、冷却水温の少なくとも一つに応じてアイドル時の要求エンジントルクを設定するので、アイドル状態への移行時にアイドル時の目標回転数の高低、冷却水温の高低あるいはアイドル時の補機負荷の作動、非作動にかかわらず供給空気量や供給燃料量に過不足が生じることがなく、これによって運転フィーリングが悪くなることがない。
【０１０５】
回転数検出手段からの信号に基づいて検出されるエンジン回転数には回転数検出手段の加工誤差等に起因したノイズを含んでいるため、エンジン回転数に基づいて演算される到達予測時間がノイズの影響を受け、真値の近傍でゆらぐため、特に到達予測時間が所定時間の近傍でゆらいだときには、第１、第２、第３、第４、第５の各発明において供給空気量の補正判定出力に、また第８、第９、第１０、第１１、第１２の各発明において一燃焼当たりの供給燃料量の補正判定出力に不要なチャタリングが生じてしまうことになるが、第１４の発明により到達予測時間にバックラッシュ特性処理を施した後の値と第１５の発明により到達予測時間に平均化処理を施した後の値はゆらぎのない値となることから、到達予測時間が所定時間の近傍でゆらぐことに起因して生じる不要なチャタリングを防止することができる。
【０１０６】
第１６と第１７の各発明では、供給空気量または一燃焼当たりの供給燃料量の増量によるアイドル状態への移行時の回転数制御とアイドル回転数のフィードバック制御との間に待ち時間をおくことなく、供給空気量または一燃焼当たりの供給燃料量の増量によるアイドル状態への移行時の回転数制御に引き続いてアイドル回転数のフィードバック制御が行われるので、アイドル回転数のフィードバック制御を開始する直前においてエンジン発生トルクの過不足がなく、これによってアイドル回転数のフィードバック制御の負担が軽減され、アイドル時の目標回転数への収束性が一段とよくなる。
【０１０７】
第１８の発明では、エンジン回転数がアイドル回転数のフィードバック制御における制御開始回転数に到達したときのあるいは到達する直前におけるエンジントルクがアイドル時の要求エンジントルクより低いときには点火時期をさらに進角させる（発生トルクを増加させる）ことで、回転数の落ち込みの回避を確実にし、またエンジン回転数が制御開始回転数に到達したときのエンジントルクがアイドル時の要求エンジントルクより高いときにはさらに点火時期を遅角させる（発生トルクを減少させる）ことで、回転数の吹き上がりの回避を確実にすることができる。
【図面の簡単な説明】
【図１】第１実施形態の制御システム図である。
【図２】アイドル状態への移行時の回転数制御を説明するためのフローチャートである。
【図３】各種状態量の検出を説明するためのフローチャートである。
【図４】アイドル時の要求吸気管内圧力ＢＩＤＬＥの演算を説明するためのフローチャートである。
【図５】供給空気量の補正の判定を説明するためのフローチャートである。
【図６】供給空気量ＱＡＬＬの演算を説明するためのフローチャートである。
【図７】動的エンジンモデルを示すブロック図である。
【図８】規範モデル出力Ｂｏｏｓｔ ｍ、平衡吸気管内圧力Ｂｏｏｓｔ ｓｔａｔｉｃ、供給空気量ＱＡＬＬ、吸気管内圧力Ｂｏｏｓｔのアイドル状態への移行時の波形図である。
【図９】第１実施形態の作用を説明するための波形図である。
【図１０】第１実施形態の作用を説明するための波形図である。
【図１１】第２実施形態の供給空気量ＱＡＬＬの演算を説明するためのフローチャートである。
【図１２】第３、第４の各実施形態のアイドル状態への移行時の回転数制御を説明するためのフローチャートである。
【図１３】第３、第４の各実施形態のアイドル時の要求空気量ＱＩＤＬＥの演算を説明するためのフローチャートである。
【図１４】第３実施形態の供給空気量ＱＡＬＬの演算を説明するためのフローチャートである。
【図１５】第４実施形態の供給空気量ＱＡＬＬの演算を説明するためのフローチャートである。
【図１６】第５実施形態の供給空気量の補正の判定を説明するためのフローチャートである。
【図１７】第５実施形態のバックラッシュ特性処理を説明するための波形図である。
【図１８】バックラッシュ特性処理の説明図である。
【図１９】バックラッシュ特性処理の説明図である。
【図２０】従来例の作用を説明するための波形図である。
【図２１】従来例の作用を説明するための波形図である。
【図２２】従来例の作用を説明するための波形図である。
【図２３】従来例の作用を説明するための波形図である。
【図２４】第１の発明のクレーム対応図である。
【図２５】第２の発明のクレーム対応図である。
【図２６】第３の発明のクレーム対応図である。
【図２７】第８の発明のクレーム対応図である。
【図２８】第９の発明のクレーム対応図である。
【図２９】第１０の発明のクレーム対応図である。
【符号の説明】
６ 燃料噴射弁
１１ ＥＣＵ
１５ クランク角センサ
１６ エアフローメータ
２０ 補助空気弁[0001]
[Industrial applications]
The present invention relates to an engine speed control device, and particularly to a target engine speed during idling without a decrease in engine speed when shifting from a load operation state in which an accelerator pedal is depressed to an idle state in which the accelerator pedal is released. It relates to something that converges quickly to a number.
[0002]
[Prior art]
At the time of the transition from the load operation state to the idle state, the generated torque of the engine is reduced due to the shortage of the supplied air amount, and the engine speed may be significantly lower than the target speed at the time of idling. When the switch from the open state to the closed state of the throttle valve is detected, the supply air amount of the throttle section is temporarily increased, and then the air amount is gradually reduced. There has been proposed a device (refer to Japanese Patent Publication No. 64-4062) in which the torque generated by the engine is increased to avoid a drop in the engine speed.
[0003]
[Problems to be solved by the invention]
However, in this device, since the supply air amount is increased for a certain period from the switching timing of the throttle valve to the closed state, depending on how the supply air amount is increased, as shown in FIG. The increase in the amount of supply air ends before the rotation speed reaches the target rotation speed during idling, and when the rotation speed reaches the target rotation speed, the generated torque of the engine is insufficient and a fall in the engine rotation speed may not be avoided. Was. To avoid such a drop in engine speed, increase the amount of air supply or increase the rate of decrease in the amount of air supply thereafter, so that even when the engine speed reaches the target engine speed during idling, Although the increase in air volume is continued, it is possible to avoid a drop in the number of revolutions, but on the other hand, the time from when the throttle valve is closed to when the engine revolution reaches the target revolution during idling is prolonged, and the driving feeling Gets worse. Therefore, it is necessary to adapt the increase amount of the supply air amount and the subsequent decrease speed of the increase amount by a trade-off between the decrease in the rotational speed and the convergence to the target rotational speed during idling. However, since the degree of the decrease in the rotational speed is significantly different from the operating conditions, it is desirable to improve the convergence to the target rotational speed during idling while preventing the decrease in the rotational speed for all the operating conditions having different degrees of the decrease. It is difficult to adapt to
[0004]
In order to solve such difficulties, the second device disclosed in Japanese Patent Application Laid-Open No. 3-67047 discloses (1) increasing the first supply air amount from the timing of switching the throttle valve to the closed state, and (2) When the engine rotation speed reaches a predetermined rotation speed (for example, 1200 rpm) provided at a place higher than the target rotation speed during idling by a predetermined value, the second supply air amount is increased and the first supply air amount is increased. By shortening the increase period and setting the initial value of the increase amount of the second supply air amount so small that the rotation speed does not drop, convergence to the target rotation speed at the time of idling while preventing the rotation speed from dropping is prevented. (See FIG. 22).
[0005]
However, also in the second device, it cannot be said that the dynamic delay from the time when the supply air amount is increased to the time when the generated torque of the engine (hereinafter referred to as engine torque) rises is not sufficiently considered. Depending on the operating conditions, the number of rotations may drop. Since there is a delay of about several hundred milliseconds depending on the collector capacity of the intake manifold between the time when the engine torque rises after the supply air amount is increased, for example, the first supply air amount increase after the throttle valve is closed. Immediately after the end, under a driving condition in which a large load is applied to the engine and the number of revolutions drops at a rapid descent rate (see FIG. 23), the intake pipe pressure (corresponding to the engine torque) even if the second supply air amount is increased. Does not rise sufficiently and spins down.
[0006]
Further, in the above two devices, the supply air amount at the time of transition to the idle state is not always a value corresponding to all of the operating conditions. Could be worse. In other words, in order to converge to the target rotational speed during idling without decreasing the rotational speed, the pressure in the intake pipe when the rotational speed reaches the target rotational speed in idle is near the required intake pipe pressure in idle. (I.e., it has a potential to generate a torque that can save the drop in the rotational speed). The required intake pipe pressure during idling is determined by the target rotational speed, cooling water temperature, or auxiliary equipment connected to the engine output shaft. Since the pressure changes according to the operating state of the load, etc., the pressure in the intake pipe when the engine speed reaches the target engine speed during idling, the engine speed during idling corresponding to the target engine speed, cooling water temperature or the operating condition of the auxiliary load Must be near the required intake pipe pressure.
[0007]
However, in the above two devices, the intake pipe pressure at the time when the rotation speed reaches the target rotation speed at the time of idling is the required intake pipe pressure at the time of idling corresponding to the target rotation speed, the cooling water temperature or the operating state of the auxiliary equipment load. For example, when the auxiliary equipment load is small, the supply air amount may become excessively small, and the engine rotation speed temporarily rises due to the excessive supply air amount, resulting in poor driving feeling. It becomes. Further, when the load of the auxiliary equipment is large, the supply air amount may become insufficient and the rotation speed may drop.
[0008]
Therefore, according to the present invention, the engine torque when the engine speed reaches the idle speed at the time of transition to the idle state is equal to the required engine torque at the time of idling by the control method of following the reference model using the dynamic engine model. By calculating the supplied air amount and the supplied fuel amount per combustion as described above, and supplying the air amount and the fuel amount, the rotational speed can be reduced no matter how the rotational speed drops during the transition to the idle state. It is an object of the present invention to quickly converge to a target rotation speed without dropping.
[0009]
[Means for Solving the Problems]
In the first invention, as shown in FIG. 24, a means 31 for detecting the engine speed NE is provided at the time of shifting to the idle state.The time T required for the throttle valve to reach the idle speed assuming that the throttle valve is in the fully closed position, the rate of decrease of the engine speed is equal to or more than a predetermined value, and the rate of decrease continues as it is. reach , And the estimated arrival time T reach When the correction of the supply air amount is started when is within the predetermined time T0,Determining means 32 and a control method for following a reference model using a dynamic engine model that uses the supplied air amount and the engine torque as input and output when it is determined that the correction of the supplied air amount is to be started. Means 33 are provided for calculating the supply air amount QALL so that the engine torque at the time when the number reaches the required engine torque at the time of idling, and means 34 for supplying the supply air amount QALL to the engine.
[0010]
In the second invention, as shown in FIG. 25, a means 31 for detecting the engine speed NE is provided at the time of shifting to the idle state.The time T required for the throttle valve to reach the idle speed assuming that the throttle valve is in the fully closed position, the rate of decrease of the engine speed is equal to or more than a predetermined value, and the rate of decrease continues as it is. reach , And the estimated arrival time T reach When the correction of the supply air amount is started when is within the predetermined time T0,A determination means for determining whether or not the supply air amount required to maintain the required engine torque during idling steadily at the current engine speed when the correction of the supply air amount is to be started is determined by the request engine required during idling; A means 41 for calculating according to the torque and the engine speed NE and a means 34 for supplying the supplied air amount QALL to the engine are provided.
[0011]
According to the third invention, as shown in FIG. 26, a means 31 for detecting the engine speed NE is provided at the time of shifting to the idle state.The time T required for the throttle valve to reach the idle speed assuming that the throttle valve is in the fully closed position, the rate of decrease of the engine speed is equal to or more than a predetermined value, and the rate of decrease continues as it is. reach , And the estimated arrival time T reach When the correction of the supply air amount is started when is within the predetermined time T0,The determination means 32, and when it is determined that the correction of the supply air amount is to be started, the cylinder air amount per combustion at the current engine speed and the required cylinder air amount per combustion at idling are steadily determined. Means 51 are provided for calculating the supply air amount QALL required to make them coincide with each other in accordance with the required engine torque during idling, and means 34 for supplying the supply air amount QALL to the engine.
[0012]
According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the idling is performed according to at least one of an auxiliary load acting on the engine during idling, a target rotational speed NETARGET during idling, and a coolant temperature TW. Set the required engine torque at the time.
[0014]
No.5In the invention of theAny one of 1 to 4In the invention, the predetermined time T0 is given according to a dynamic delay time from the operation of the supply air amount to the rise of the engine torque.
[0015]
No.6According to the invention, the amount corresponding to the engine torque in any one of the first to fourth inventions is the intake pipe pressure.
[0016]
No.7According to the invention of any one of the second to fourth inventions, the amount corresponding to the engine torque is the air flow rate.
[0017]
No.8According to the invention of FIG. 27, as shown in FIG.The time T required for the throttle valve to reach the idle speed, assuming that the throttle valve is in the fully closed position, the rate of decrease of the engine speed is equal to or more than a predetermined value, and the rate of decrease DNE continues as it is. reach , And the estimated arrival time T reach When the correction of the supplied fuel amount per combustion is started whenA control means for following a reference model by using a dynamic engine model having input / output of the supplied fuel amount per combustion and the engine torque when it is determined that the correction of the supplied fuel amount per combustion is to be started; Means 62 for calculating the amount of fuel supplied per combustion so that the engine torque when the engine speed reaches the idle speed matches the required engine torque during idling, and supplies the supplied fuel amount to the engine. And means 63 for performing the operations.
[0018]
No.9In the invention of FIG. 28, as shown in FIG. 28, the means 31 for detecting the engine speed NE is provided withThe time T required for the throttle valve to reach the idle speed, assuming that the throttle valve is in the fully closed position, the rate of decrease of the engine speed is equal to or more than a predetermined value, and the rate of decrease DNE continues as it is. reach , And the estimated arrival time T reach When the correction of the supplied fuel amount per combustion is started whenDetermining means 32 and, when it is determined that the correction of the supplied fuel amount per combustion is to be started, the supplied fuel per combustion necessary to constantly maintain the required engine torque at idling at the current engine speed. Means 71 for calculating the amount according to the required engine torque during idling and the engine speed NE, and means 63 for supplying the supplied fuel amount per combustion to the engine are provided.
[0019]
No.10In the invention of FIG. 29, as shown in FIG. 29, the means 31 for detecting the engine speed NE is provided withThe time T required for the throttle valve to reach the idle speed, assuming that the throttle valve is in the fully closed position, the rate of decrease of the engine speed is equal to or more than a predetermined value, and the rate of decrease DNE continues as it is. reach , And the estimated arrival time T reach When the correction of the supplied fuel amount per combustion is started whenThe determination means 61 steadily calculates the fuel amount per combustion at the current engine speed and the required fuel amount per combustion at idling when it is determined that the correction of the supplied fuel amount per combustion is started. Means 81 are provided for calculating the amount of fuel supplied per combustion necessary for making them coincide with each other in accordance with the required engine torque at the time of idling, and means 63 for supplying the amount of fuel supplied per combustion to the engine are provided.
[0020]
No.11In the invention of the8From the first10In any one of the above inventions, the required engine torque during idling is set according to at least one of the auxiliary load acting on the engine during idling, the target rotational speed NETARGET during idling, and the cooling water temperature TW.
[0022]
No.12In the invention of theAny one of 8 to 11In the invention, the predetermined time T0 is given according to the dynamic delay time from the operation of the supplied fuel amount per combustion to the rise of the engine torque.
[0023]
No.ThirteenIn the invention of the8From the first11In any one of the above inventions, the amount corresponding to the engine torque is the fuel amount per combustion.
[0024]
No.14In the invention of the1, 2nd, 3rd, 4th, 5th, 8th, 9th, 10th, 11th, 12thIn any one of the inventions, a backlash characteristic process is performed on the predicted arrival time Treach.
[0025]
No.FifteenIn the invention of the1, 2nd, 3rd, 4th, 5th, 8th, 9th, 10th, 11th, 12thIn any one of the inventions, an averaging process is performed on the predicted arrival time Treach.
[0026]
No.16In the invention of theAny one of 1 to 5In the case of performing the feedback control of the idle speed in the invention of the third aspect, when the engine speed reaches the control start speed of the feedback control, the correction of the supply air amount ends.
[0027]
No.17In the invention of theAny one from 8 to 12In the present invention, when performing the feedback control of the idle speed, when the engine speed reaches the control start speed of the feedback control, the correction of the supplied fuel amount per combustion is ended.
[0028]
No.18In the invention of the16Or the first17In the invention, the ignition timing is controlled such that the engine torque when the engine speed reaches or immediately before the control start speed NSTART matches the required engine torque during idling.
[0029]
[Action]
In contrast to the conventional example in which the dynamic delay from increasing the supply air amount until the intake pipe pressure (equivalent to engine torque) rises has not been sufficiently taken into consideration, the first invention corrects the supply air amount. When it is determined that the engine is to be started, the demand for the engine torque when the engine speed reaches the idle speed by the control method of following the reference model using the dynamic engine model that uses the supply air amount and the engine torque as the input and output. Since the supply air amount is calculated to match the engine torque and this supply air amount is supplied to the engine, the supply air amount must be operated in anticipation of the dynamic delay from the operation of the supply air amount to the increase of the engine torque. No matter how the engine speed drops during the transition to the idle state, the engine speed can be reduced without sacrificing the engine speed. It can be converged quickly to the target speed.
[0030]
Similarly,8According to the invention, when it is determined that the correction of the supplied fuel amount per combustion is started, the engine is controlled by a control method of following a reference model using a dynamic engine model that inputs and outputs the supplied fuel amount per combustion and the engine torque. Since the amount of fuel supplied per combustion is calculated so that the engine torque when the rotational speed reaches the idling rotational speed matches the required engine torque at the time of idling, and the supplied fuel amount per combustion is supplied to the engine, It is possible to control the amount of fuel supplied per combustion in anticipation of a dynamic delay from the operation of the amount of fuel supplied per combustion to an increase in engine torque. , The speed can be quickly converged to the target speed without lowering the speed. In addition8According to the invention, even if the lean burn system (a system in which fuel is burned at a mixture ratio smaller than the stoichiometric air-fuel ratio when the lean operation condition is satisfied) is not provided with a means for adjusting the supply air amount, It is possible to increase the amount of fuel supplied per combustion in anticipation of the dynamic delay from the operation of the supplied fuel amount to the increase in engine torque, and to reduce the rotational speed to the idling rotational speed while avoiding a decrease in the rotational speed. It can be quickly converged.
[0031]
In each of the second and third inventions, although the dynamic engine model is not used, the air amount is increased in advance in anticipation of the dynamic delay before the engine speed falls to the idle speed. It is possible to compensate for a dynamic delay from the operation of until the engine torque rises.
[0032]
Similarly,9,10In each of the inventions, although the dynamic engine model is not used, the amount of fuel per combustion is increased in advance in anticipation of a dynamic delay before the engine speed falls to the idle speed, so It is possible to compensate for a dynamic delay from the operation of the supplied fuel amount to the rise of the engine torque.
[0033]
2nd, 3rd, 3rd9,10In each of the inventions described above, the present invention can be realized even when the dynamic engine model is not well understood, and the amount of calculation is small because the digital filter calculation is unnecessary. Third, third10Each of the inventions has another merit that it is not necessary to have a map in the ROM.
Further, in any one of the first to third inventions, it is assumed that the throttle valve is in the fully-closed position, the descent rate of the engine speed is equal to or more than a predetermined value, and the descent rate continues until the idle speed is reached. Time, and when it is determined that the predicted arrival time is within a predetermined time, it is determined that the correction of the supply air amount is to be started. Assuming that the rotational speed descent rate is equal to or more than a predetermined value and the descent rate continues as it is, the time until the idle speed is reached is predicted. Since it is determined that the correction of the fuel amount is to be started, the engine torque when the engine speed reaches the idle speed approaches the required engine torque during idling with good tracking. It is possible.
[0034]
4th and 4th11In each of the inventions, the required engine torque at the time of idling is set according to at least one of the auxiliary load acting on the engine at the time of idling, the target rotation speed at the time of idling, and the cooling water temperature. Regardless of whether the target engine speed is high or low, whether the cooling water temperature is high or low, or whether the auxiliary equipment load is operating or not operating during idling, there is no excess or deficiency in the amount of supplied air or supplied fuel, thereby deteriorating the driving feeling. Nothing.
[0036]
The engine rotation speed detected based on the signal from the rotation speed detection means includes noise due to a processing error of the rotation speed detection means and the like, and the estimated arrival time calculated based on the engine rotation speed is a noise. And fluctuates in the vicinity of the true value, especially when the predicted arrival time fluctuates in the vicinity of the predetermined time.1, 2nd, 3rd, 4th, 5thIn each invention of the above, the correction judgment output of the supplied airEighth, ninth, tenth, eleventh, twelfthIn each of the inventions described above, unnecessary chattering may occur in the correction determination output of the supplied fuel amount per combustion.14The value after performing the backlash characteristic processing on the estimated arrival time according to the invention ofFifteenSince the value after performing the averaging process on the predicted arrival time according to the invention is a value without fluctuation, it is possible to prevent unnecessary chattering caused by fluctuation in the predicted arrival time near the predetermined time. it can.
[0037]
No.16And the second17In each of the inventions described above, the supply air amount can be reduced without a waiting time between the rotation speed control at the time of transition to the idle state and the idle speed feedback control by increasing the supply air amount or the supply fuel amount per combustion. Alternatively, the feedback control of the idle speed is performed subsequent to the rotation speed control at the time of transition to the idle state due to the increase of the supplied fuel amount per combustion, so that the engine generated torque is reduced immediately before the start of the feedback control of the idle speed. There is no excess or deficiency, thereby reducing the load on the feedback control of the idle speed, and the convergence to the target speed during idling is further improved.
[0038]
No.18According to the invention, the ignition timing is further advanced when the engine torque reaches or immediately before the engine rotation speed reaches the control start rotation speed in the idle speed feedback control, when the engine torque is lower than the required engine torque at the time of idling. By increasing the torque), it is possible to avoid a drop in the rotation speed, and to further retard the ignition timing when the engine torque when the engine rotation speed reaches the control start rotation speed is higher than the required engine torque during idling. By doing so (reducing the generated torque), it is possible to reliably avoid the rotational speed from rising.
[0039]
【Example】
In FIG. 1, reference numeral 1 denotes an engine body. The intake air flows in from the air cleaner 2, and its flow rate is adjusted by a throttle valve 3 linked with an accelerator pedal. Supplied. Fuel is injected from the fuel injection valve 6 toward the intake port based on an injection signal from the ECU 11.
[0040]
Gas in the cylinder is ignited by an ignition device including a power transistor that receives an ignition signal from the ECU 11, an ignition coil, a distributor 12, and an ignition plug 13, and the gas burned in the cylinder is discharged to an exhaust passage 8. The three-way catalyst 9 purifies HC, CO, and NOx in the exhaust gas.
[0041]
The ECU 11 has a Ref signal and a 1 ° signal from a crank angle sensor 15 built in the distributor 12, an intake air amount signal from an air flow meter 16, a throttle opening signal from a throttle sensor 17, and a cooling water temperature signal from a water temperature sensor 18. The fuel injection amount (air-fuel ratio) and the ignition timing are controlled while determining the operation state based on these.
[0042]
An auxiliary air passage 19 that bypasses the throttle valve 3 is provided with a rotary solenoid type auxiliary air valve 20 that operates directly according to an output signal from the ECU 11. The auxiliary air valve 20 is driven ON-OFF at a constant frequency, and the amount of auxiliary air increases as the ON time ratio increases.
[0043]
The ECU 11 sets a target rotation speed (hereinafter simply referred to as a target rotation speed) NETARGET based on the cooling water temperature, the elapsed time after the start, the battery voltage, the power steering hydraulic switch, the air conditioner switch, the selector position of the automatic transmission, and the like. When the actual rotation speed deviates from the target rotation speed by 25 rpm or more, feedback control of the idle rotation speed is performed so as to approach the target rotation speed. In this feedback control, when the rotation speed is lower than the target rotation speed by 25 rpm or more, the above-described ON time ratio (that is, the ON duty) is increased to increase the amount of auxiliary air. The duty is reduced to reduce the amount of auxiliary air. Note that a FICD solenoid (not shown) is formed integrally with the auxiliary air valve 20, and when the air conditioner is operated, the target rotation speed is controlled by the auxiliary air valve 20 and the FICD solenoid.
[0044]
By the way, in order to improve the convergence to the target rotation speed while preventing the rotation speed from dropping during the transition from the load operation state to the idle state, (1) a certain period from the switching timing of the throttle valve 3 to the closed state, A configuration in which the supply air amount is increased, or (2) an increase in the first supply air amount from the timing of switching the throttle valve 3 to the closed state is provided at a position higher than the target rotation speed by a predetermined value thereafter. When the engine rotation speed reaches the first rotation speed, the second supply air amount is increased, the increase period of the first supply air amount is shortened, and the initial value of the increase amount of the second supply air amount is reduced. There is a configuration in which the rotation speed is set to a small value so that the rotation speed does not drop.However, in these devices, a dynamic delay from when the supply air amount is increased to when the engine torque rises is sufficiently considered. I can't say No reason, there is the rotational speed at the time of transition to the idle state by the operating conditions falls below the target speed.
[0045]
Further, in the apparatus having the above two configurations, the pressure in the intake pipe at the time when the rotation speed reaches the target rotation speed is equal to the target rotation speed, the coolant temperature, or the idling time corresponding to the operation state of the auxiliary load driven by the engine. Since it is not set to be close to the required intake pipe pressure, for example, when the auxiliary equipment load is small, the supplied air amount may be excessive, and when the auxiliary equipment load is large, the supplied air amount may be insufficient. The engine speed temporarily rises due to the excessive amount, and the speed decreases due to the shortage of the supplied air amount, and in any case, the driving feeling deteriorates.
[0046]
In order to deal with this, in the first embodiment,
(1) A dynamic engine model having input and output of the supply air amount and the intake pipe pressure is provided in advance,
(2) When the predicted time until the throttle valve is in the fully closed position, the descent rate of the engine speed is equal to or more than a predetermined value, and reaches the idle speed is within a predetermined time T0, the correction start timing is set as
(3) Calculate the required intake pipe pressure during idling (corresponding to the required torque during idling) BIDLE according to the target rotational speed NETARGET, the cooling water temperature TW, and the operating state of the auxiliary load driven by the engine;
{Circle around (4)} The supply air amount by the control method of following the reference model using the above dynamic engine model so that the intake pipe pressure when the engine speed reaches the idle speed and this required intake pipe pressure BIDLE match. Calculate QALL,
(5) The auxiliary air valve 20 is controlled so that the supplied air amount QALL flows through the throttle section.
[0047]
The contents of this control executed by the ECU 11 will be described with reference to the following flowchart.
[0048]
The flowchart of FIG. 2 is a main routine for controlling the number of revolutions at the time of transition to the idle state, and is executed at regular intervals (for example, every 10 ms).
[0049]
First, in step 1, the engine speed NE, the rate of decrease DNE of the engine speed, the coolant temperature TW, and the throttle opening TVO are read. The detection of these state quantities will be described with reference to the flow of FIG. The job in FIG. 3 is an interrupt job triggered by the rise of the Ref signal.
[0050]
In steps 11 and 12, the interval TREF [s] of the Ref signal rising every combustion (every 180 ° in crank angle for a four-cylinder engine, and every 120 ° for a six-cylinder engine) is measured by a built-in timer of the ECU 11. In both cases, the engine speed is shifted. Since the previous engine speed is required to calculate the engine speed lowering rate DNE, which will be described later, the value stored in the engine speed NE (configured as a memory) is moved to the memory NE (old). is there. Therefore, the rotation speed at the previous calculation timing is stored in the memory NE (old).
[0051]
In step 13
NE [rpm] = 30 / TREF [s] (1)
The engine speed NE [rpm] is calculated by the following equation, and using this NE, NE (old) and TREF,
DNE [rpm / s] = {NE (old) -NE} / TREF (2)
Is calculated by the following equation: DNE [rpm / s]
[0052]
In step 15, a predetermined table TABLE is obtained from the output voltage of the water temperature sensor 18. A predetermined table TABLE is obtained from the coolant temperature TW by searching the TW, and from the output voltage of the throttle sensor 17 in step 16. The TVO is searched to determine the throttle opening TVO. Here, the table TABLE TW sets the sensor output voltage to the cooling water temperature and the table TABLE TVO is used to convert the sensor output voltage to the throttle opening, and is stored in the ECU 11 in advance as ROM data.
[0053]
Note that a table described later (for example, TABLE NETARGET) and maps (eg MAP B1, MAP Q, MAP Since Q2) and the like are all ROM data, description of this point is omitted.
[0054]
When the state quantities of NE, DNE, TW, and TVO are detected in this way, the process returns to step 2 of FIG. 2 to set the target rotation speed NETARGET [rpm]. For example, a predetermined table TABLE is obtained from the cooling water temperature TW. Search for NETARGET and ask.
[0055]
In step 3, the required intake pipe pressure BIDLE [Pa] during idling is calculated according to the target rotation speed NETARGET, the cooling water temperature TW, and the operating state of the air conditioner. The calculation of BIDLE will be described with reference to FIG. The job in FIG. 4 is a 10 ms job.
[0056]
In step 21, a predetermined map MAP is calculated from the target rotation speed NETARGET [rpm] and the cooling water temperature TW. B1 is searched to find a basic value B1 [Pa] of the required intake pipe pressure during idling. In step 22, the air conditioner flag ACSW is checked, and when ACSW = 1 (air conditioner operating state), a predetermined value BAC (for example, 4 kPa) is put in the memory B2 in step 23, and in step 25, the value of the memory B2 is set to the above-described basic value. The value added to the value B1 is obtained as BIDLE. B1 is the pressure in the intake pipe required to maintain the idle speed at the target speed in the no-load state of the engine. When the air conditioner is operating, the idle speed is lower than the target speed by the amount that the air conditioner load acts on the engine. Therefore, when the air conditioner is operating, the required intake pipe pressure is increased by the BAC. Therefore, when ACSW = 0 (when the air conditioner is not operating), it is not necessary to increase the amount, and the process proceeds from step 22 to step 24, where 0 is inserted into B2.
[0057]
After calculating the required intake pipe pressure BIDLE at the time of idling in this way, the flow returns to step 4 in FIG. 2 to determine whether or not the supply air amount is to be corrected. This determination will be described with reference to the flowchart of FIG. The job in FIG. 5 is a 10 ms job.
[0058]
The determination is made by checking the contents of steps 41, 42, and 44 one by one. When all of the items are satisfied, the correction of the supply air amount is permitted. Ban. That is,
Step 41: the throttle opening TVO is 0 (the throttle valve is in the fully closed position),
Step 42: the engine speed descent rate DNE is greater than a predetermined value DNE0 (the engine speed has dropped sharply);
Step 44: The predicted time Treach [s] until the engine speed reaches the control start speed NSTART (NETARGET + 25) [rpm] of the idle speed feedback control is equal to or shorter than a predetermined time T0 [s].
At this time, in step 45, the correction permission flag FPLUS is set to "1". Otherwise, the process proceeds to step 46, where the correction permission flag FPLUS is reset to "0".
[0059]
The above-described estimated arrival time Treach is based on the assumption that the rotational speed descent rate DNE at the calculation timing of the Treach continues as it is, and in step 43,
Treach = (NE-NSTART) / DNE (3)
It is calculated by the following equation. For example, when the engine speed NE at the current calculation timing is 2000 [rpm], NSTART is 1000 [rpm], and the speed reduction rate DNE is -2000 [rpm / s], the engine speed reaches NSTART from the rotation speed NE at the current calculation timing. Time to do

Is predicted.
[0060]
The predetermined time T0 is a dynamic delay time until the pressure in the intake pipe rises when the auxiliary air valve 20 is opened stepwise. For example, a time (for example, 800 ms) from when the auxiliary air valve 20 is opened to when the internal pressure of the intake pipe before the opening operation of the auxiliary air valve 20 and the internal pressure of the intake pipe after the opening operation reach 9: 1. It is.
[0061]
Since the correction of the supply air amount must be performed in anticipation of the dynamic delay from the increase in the air amount to the increase in the intake pipe pressure, the correction start timing is shorter than the timing when the engine speed drops to the idle speed. It needs to be earlier by the dynamic delay time. In order to determine the correction start timing, it is necessary to predict the timing at which the engine speed drops to the idle speed, and to sequentially determine whether or not the predicted timing is before the above-mentioned dynamic delay time. is there. In this way, the predicted arrival time up to the idling rotational speed is sequentially obtained, and the correction is started when the value becomes shorter than the above-mentioned dynamic delay time.
[0062]
Although not shown in FIG. 5, the timing of the end of the correction is the control start rotation speed NSTART (= NETARGET + 25) [rpm] of the idle rotation speed feedback control. The reason why the correction end timing is set to NSTART is to avoid interference between the correction control of the present invention and the idle speed feedback control.
[0063]
After determining whether to correct the supply air amount in this way, the process returns to step 5 in FIG. 2 to calculate the supply air amount QALL at the time of transition to the idle state. This calculation method will be described with reference to FIG. The job in FIG. 6 is a 10 ms job.
[0064]
In steps 51 and 52, the current state of the flag FPLUS and the previous state of the flag FPLUS are checked. If FPLUS = 1 this time and FPLUS = 0 last time (when the flag FPLUS is switched from "0" to "1"), the process proceeds to step 53. Then, the intake pipe pressure P obtained by the pressure sensor 21 (see FIG. 2) provided in the collector 4 is set to an initial value Binit. This time, when FPLUS = 1 in the previous time, skip step 53 and proceed to step 54.
Boost static (t)
= {Gm (z) / G (z)} × (BIDLE-Binit) + Binit ... (4)
Here, Gm (z): reference model characteristic
G (z): first-order lag characteristic
Boost in the balanced intake pipe by the formula Calculate static (t) and calculate this Boost At step 55, a predetermined map MAP is obtained from static (t) and the engine speed NE. The supply air amount QALL is obtained by searching Q. Note that QALL is a value from 0.
[0065]
Here, Boost static (t) is the actual intake pipe pressure Boost (t) is the reference output Boost The balanced intake pipe pressure equal to m (t) (described later), QALL, indicates that the balanced intake pipe pressure is Boost at the current rotational speed. The amount of supplied air is such that static (t) is obtained.
[0066]
The supply air amount QALL is obtained by a control method that follows a reference model using a dynamic engine model.
[0067]
Here, the dynamic engine model is a difference equation (in other words, a digital filter) that describes how the pressure in the intake pipe changes with time when the supply air amount is operated. According to the dynamic engine model, it is known how the pressure in the intake pipe changes with time when the supply air amount is manipulated. Conversely, it is desired to set the pressure in the intake pipe to a predetermined pressure after a predetermined time. It is also clear how to control the supply air volume at times. Using this principle, the supply air amount QALL is adjusted so that the required intake pipe pressure BIDLE at the time of idling is obtained when the engine speed drops to the idle speed.
[0068]
Since a control method for following the reference model is known, it will be briefly described below with reference to FIGS. Now, as shown in FIG. 7, the rotational speed NE and the supply air amount QALL are input, and the balanced intake pipe pressure Boost at the time of the input. Map MAP that outputs static Boost and pressure Boost in the equilibrium intake pipe A dynamic engine model in which a delay characteristic from static to actual intake pipe pressure Boost is approximated by a first-order delay and a characteristic G (z) is connected in series is virtually considered.
[0069]
Equilibrium intake pipe pressure Boost Since both the static and the actual intake pipe pressure Boost are functions of the time t, Boost When represented as static (t) and Boost (t),
Boost (t) = G (z) × Boost static (t)… (5)
It is.
[0070]
The response characteristic G (z) in equation (5) is, for example,
G (z) = (1 + a1) z^-1/ (1 + a1 × z^-1…… (6)
Where a1: coefficient
(G (1) = 1), and more specifically, can be configured by a digital primary low-pass filter (see FIG. 7).
[0071]
Here, the coefficient a1 in the equation (6) is determined by the response characteristics from the time when the auxiliary air valve 20 is opened in a stepwise manner to the time when the intake pipe pressure rises with a delay.
[0072]
Further, a desirable response characteristic (reference model characteristic Gm (z)) of the pressure in the intake pipe when the flag FPLUS is switched from “0” to “1” is changed from the switching timing of the flag FPLUS from “0” to “1”. At least after a predetermined time T0, the intake pipe pressure becomes close to the required intake pipe pressure BIDLE during idling, for example.
Gm (z)=(1 + c1) z^-2/ (1 + c1 × z^-1…… (7)
Where c1: a coefficient that determines the characteristics of the reference model
(Gm (1) = 1). At this time, after FPLUS is switched from "0" to "1" (t = 0 at this switching timing), the pressure in the intake pipe immediately before the switching is set to the initial value Binit, and BIDLE is finally converged. Value

Transient intake pipe pressure (reference output Boost) m (t)) (see the second row in FIG. 8).
[0073]
The actual intake pipe pressure Boost (t) is converted to the reference output Boost of the above equation (8). To match m (t),
G (z) × Boost static (t) = Boost m (t)
Since the equation must be satisfied, this equation is changed to Boost The static (t) will be organized.
[0074]
Boost static (t) = Boost m (t) / G (z)
Substituting equation (8) into the right side of this equation gives

And the above equation (4) is obtained.
[0075]
In this manner, the supply air amount QALL can be calculated such that the intake pipe pressure when the engine speed reaches the control start speed NSTART in the idle speed feedback control is equal to the required intake pipe pressure BIDLE. (See the fourth row in FIG. 8).
[0076]
Note that the calculation of the {Gm (z) / G (z)} portion of the above equation (4) is a generally known digital operation, and thus the description is omitted.
[0077]
After the supply air amount QALL is calculated in this manner, the process returns to step 6 in FIG. 2 to determine the ON duty to be given to the auxiliary air valve 20 according to QALL-QLEK, and transfers this to the output register for auxiliary air valve control in step 7. . After this transfer, the ON duty is converted into a PWM signal and output to the auxiliary air valve 20, and the PWM control is performed so that the amount of air flowing through the auxiliary air valve 20 becomes QALL-QLEAK. The ON duty (that is, the opening degree of the auxiliary air valve) is defined as the air flow of the auxiliary air valve section when the total of the flow rates of air supplied from other than the auxiliary air valve 20 to the engine (the flow rate of air leaking from the throttle valve 3) is QLEAK. That is, the flow rate is determined so as to have an opening degree of QALL-QLEAK. QLEAK is measured experimentally.
[0078]
Here, the operation of the present embodiment will be described.
[0079]
In contrast to the conventional example in which the dynamic delay from increasing the supply air amount until the intake pipe pressure (equivalent to engine torque) rises was not sufficiently considered, in the present embodiment, when the supply air amount is operated A dynamic engine model that describes how the pressure in the intake pipe changes with time is provided until the throttle valve reaches the fully closed position, the descent rate of the engine speed exceeds a predetermined value, and reaches the idle speed. The required intake pipe pressure BIDLE at the time of idling is set according to the target rotational speed NETARGET, the cooling water temperature TW, and the operating state of the auxiliary load driven by the engine, when the predicted time is within the predetermined time T0 as the correction start timing. Is calculated so that the intake pipe pressure when the engine speed reaches the idle speed matches the required intake pipe pressure BIDLE. The supply air amount QALL is calculated by a control method that follows the reference model using the dynamic engine model described above, and the auxiliary air valve 20 is controlled so that the supply air amount QALL flows. It is possible to control the supply air amount in anticipation of a dynamic delay until the pressure in the pipe increases, so that the engine speed can be reduced no matter how the engine speed drops during the transition to the idle state (for example, when the engine speed drops rapidly as shown in FIG. 9). Even when the vehicle slowly descends as shown in FIG. 10), the rotational speed can be quickly converged to the target rotational speed without lowering the rotational speed.
[0080]
Further, the pressure in the intake pipe when the rotational speed reaches the target rotational speed becomes close to the required intake pipe pressure during idling corresponding to the target rotational speed, the cooling water temperature, or the operation state of the auxiliary load driven by the engine. In the conventional example, when the auxiliary equipment load is small, for example, the supplied air amount becomes excessive and the engine speed temporarily rises, and when the auxiliary equipment load is large, the supplied air amount becomes insufficient. In this embodiment, the required intake pipe pressure during idling depends on the target rotational speed NETARGET, the cooling water temperature TW, and the operating state of the auxiliary equipment load. Since the BIDLE is calculated, when the auxiliary equipment load is small as described above, the supply air amount decreases accordingly, and the rotation speed due to the excess supply air amount is reduced. Temporal blow-up is prevented, and when the auxiliary equipment load is large, the supply air volume increases accordingly, preventing a drop in the number of revolutions due to a shortage of the supply air volume, thereby worsening the driving feeling. There is no.
[0081]
The flowchart of FIG. 11 is the second embodiment, and corresponds to FIG. 6 of the first embodiment. The same steps as those in FIG. 6 are denoted by the same step numbers. The flowcharts of FIGS. 2, 3, 4, and 5 of the first embodiment are used in the second embodiment.
[0082]
12, 13, and 14 are flowcharts of the third embodiment, flowcharts of FIGS. 12, 13, and 15 are flowcharts of the fourth embodiment. FIG. 12 is a flowchart of the first embodiment, and FIG. 4, FIG. 14 and FIG. 15 correspond to FIG. The same steps as those in the corresponding drawings are denoted by the same step numbers. FIGS. 3 and 5 are also used in the third and fourth embodiments.
[0083]
While the first embodiment uses the intake pipe pressure as the engine torque equivalent, the third and fourth embodiments use the air amount as the engine torque equivalent. More specifically, the flowchart of FIG. 13 (details of step 71 in FIG. 12) is for calculating the required air flow rate QIDLE [liter / min] during idling. In step 81, a predetermined map MAP is obtained from the target rotation speed NETARGET and the cooling water temperature TW. The basic value Q1 of the required air flow rate during idling is obtained by searching Q2. When ACSW = 1 (the operating state of the air conditioner), the routine proceeds from step 22 to step 82, where the predetermined value QAC is stored in the memory Q2 (for example, 50 liter / liter). min), and if ACSW = 0, the routine proceeds to step 83, where 0 is entered. At step 84, a value obtained by adding the value of the memory C2 to the basic value Q1 is obtained as QIDLE. Q1 is the air flow required to maintain the idle speed at the target speed in the no-load condition of the engine. When the air conditioner is operating, the idle speed is reduced by the amount that the air conditioner load acts on the engine. Sometimes the air flow is increased by the amount of the BAC. The QIDLE is shown in the fourth row of FIG. Note that Q in step 81_AFMIs the intake air flow rate obtained from the output of the air flow meter.
[0084]
In the second, third, and fourth embodiments, the dynamic engine model is not used, but the dynamic delay (that is, the supply air amount is operated) before the engine speed falls to the idle speed. In some cases, the air amount is increased in advance in anticipation of a delay until the pressure in the intake pipe rises (for example, a delay until 90% rise), thereby compensating for a dynamic delay.
[0085]
More specifically, in the second embodiment, as shown in FIG. 11, when FPLUS = 1, the routine proceeds to step 61, where a predetermined map MAP is obtained from the required intake pipe pressure BIDLE during idling and the engine speed NE. The value obtained by searching Q3 is obtained as the supply air amount QALL. The supply air amount QALL (QALL> QIDLE) at this time is a supply air amount necessary to constantly maintain the required intake pipe pressure BIDLE during idling at the current rotational speed. Similarly, in the third embodiment, as shown in FIG. 14, when FPLUS = 1, the routine proceeds to step 91, and the predetermined map MAP is calculated from the required air flow rate QIDLE during idling and the engine speed NE. The value obtained by searching Q4 is obtained as the supply air amount QALL. The supply air amount QALL (QALL> QIDLE) at this time is a supply air amount necessary to constantly maintain the required air flow rate QIDLE during idling at the current rotational speed. Map MAP Q3 and MAP Q4 is determined experimentally.
[0086]
On the other hand, the fourth embodiment proceeds to step 101 when FPLUS = 1 as shown in FIG.
QALL = (NE / NETARGET) × QIDLE (11)
The supply air amount QALL is obtained by the following equation. At this time, the supply air amount QALL (QALL> QIDLE) is determined by the cylinder air amount per combustion [liter / cyl] at the current rotation speed and the required cylinder air amount per combustion at the idling time [liter / cyl]. Is the amount of air required to constantly match with
[0087]
Here, the required cylinder air amount [liter / cyl] per one combustion (one intake) at the time of idling is, for example, 1000 [rpm] for the idling speed and 100 [liter] for the required air flow QIDLE at the time of idling. / Min], if the engine is a four-cylinder engine, the intake air (combustion) is 1000 × 2 [times / min] at the time of idling. Therefore, the value is 100 / (1000 × 2) [liter / cyl].
[0088]
In each of the second, third, and fourth embodiments, since the dynamic engine model is not used, precise control cannot be performed as in the first and second embodiments, but the same operation as in the first embodiment is performed. The effect still remains. In each of the second, third, and fourth embodiments, the present invention can be realized even when the dynamic engine model is not well understood. Since the digital filter operation is not required, the operation amount can be reduced. The fourth embodiment has another merit that it is not necessary to have a map in the ROM.
[0089]
The flowchart of FIG. 16 is the fifth embodiment, and corresponds to FIG. 5 of the first embodiment. The same steps as those in FIG. 5 are denoted by the same step numbers. The flowcharts of FIGS. 2, 3, 4, and 6 are used in the fifth embodiment.
[0090]
In this embodiment, a backlash characteristic process (filtering process) is performed on the predicted arrival time Treach at step 111, and the post-backlash characteristic process Treach and a predetermined time T0 are compared at step 112. .
[0091]
Since the engine speed NE detected based on the signal from the crank angle sensor 15 includes noise caused by a processing error of the crank angle sensor 15 and the like, the above-mentioned arrival calculated based on the engine speed NE is obtained. The predicted time Treach is affected by noise, and fluctuates near the true value as shown in FIG. 17, and particularly when the Treach fluctuates near the predetermined time T0, unnecessary chattering occurs in the correction determination output of the supplied air amount. However, since the value after performing the backlash characteristic processing on the predicted arrival time Treach according to the fifth embodiment is a value without fluctuation, it is caused by the fluctuation of Treach near the predetermined time T0. It is possible to prevent unnecessary chattering that occurs.
[0092]
Here, the backlash processing will be briefly described. The backlash processing is performed when the ball A is inserted into the housing B having a predetermined length and the ball A is moved right and left as shown in FIG. This is represented by the position of the housing B (that is, the housing B does not move even if the ball A moves in the process of C and D), and the input of the backlash is the coordinates of the ball A, and the output is the coordinates of the housing B. Corresponding to Therefore, the input / output relationship when the time is taken on the horizontal axis is as shown in FIG. 19, for example, and the backlash width is determined by the width of the housing B in the left-right direction.
[0093]
Note that by performing averaging processing instead of the backlash processing, the influence of the detection error of the rotation speed and the like can be reduced.
[0094]
Although not described in the embodiment, the intake pipe pressure (or its estimated value) when the rotation speed reaches (or immediately before) the control start rotation speed NSTART in the feedback control of the idle rotation speed is a demand at the time of idling. When the pressure is lower than the intake pipe pressure BIDLE, the ignition timing is further advanced (increased torque) to avoid the drop in the rotational speed, and the intake pipe when the rotational speed reaches the control start rotational speed NSTART. When the pressure is higher than BIDLE, the ignition timing is further retarded (the generated torque is reduced), so that it is possible to reliably prevent the rotational speed from rising.
[0095]
The calculation method of the above-described estimated arrival time Treach is not limited to the method described in the embodiment, and may be calculated using an extrapolation method such as spline interpolation. The present invention is applicable not only to an air conditioner but also to a power steering, for example.
[0096]
In the embodiment, the case where the means for supplying the air amount is the auxiliary air valve has been described, but the invention is not limited to this. For example, a so-called air-assisted injector (integrated injector) that guides auxiliary air near an injection hole of a fuel injection valve and collides the injected fuel with the auxiliary air to promote atomization of the injected fuel is taken in. Some are mounted near the valve, and in this device, the amount of air supplied can be increased by increasing the amount of auxiliary air to the air assist injector. At this time, the present invention can be applied similarly, though there is a difference that the dynamic delay time from the operation of the auxiliary air amount to the increase in the intake pipe pressure is shorter than that in the case of FIG.
[0097]
Further, either the SPI or MPI fuel amount supply means may be used instead of the air amount supply means. In this case, the same description can be made only by performing the following replacement.
[0098]
(1) Supply air amount QALL → supply fuel amount per combustion
(2) Intake pipe pressure or air flow rate → cylinder intake fuel quantity per combustion
(3) BIDLE or QIDLE → Required fuel amount per combustion at idling
(4) Auxiliary air valve opening → fuel injector opening time
[0099]
【The invention's effect】
In contrast to the conventional example in which the dynamic delay from increasing the supply air amount to the rise of the intake pipe pressure was not sufficiently considered, the first invention determines that correction of the supply air amount is to be started. The engine torque when the engine speed reaches the idle speed matches the required engine torque at the time of idling by the control method that follows the reference model using the dynamic engine model that uses the supply air amount and the engine torque as input and output. The supply air amount is calculated as described above, and the supply air amount is supplied to the engine, so that it is possible to operate the supply air amount in anticipation of a dynamic delay from the operation of the supply air amount to the increase of the engine torque. Regardless of how the engine speed drops during the transition to the state, the speed is quickly reduced to the target speed without reducing the speed. It can be.
[0100]
No.8According to the invention, when it is determined that the correction of the supplied fuel amount per combustion is started, the engine is controlled by a control method of following a reference model using a dynamic engine model that inputs and outputs the supplied fuel amount per combustion and the engine torque. Since the amount of fuel supplied per combustion is calculated so that the engine torque when the rotational speed reaches the idling rotational speed matches the required engine torque at the time of idling, and the supplied fuel amount per combustion is supplied to the engine, It is possible to control the amount of fuel supplied per combustion in anticipation of a dynamic delay from the operation of the amount of fuel supplied per combustion to an increase in engine torque. , The speed can be quickly converged to the target speed without lowering the speed. In addition8According to the invention, even if the lean burn system is not provided with a means for adjusting the supply air amount, in consideration of a dynamic delay from the operation of the supply fuel amount per combustion to the increase of the engine torque, one combustion per combustion The amount of supplied fuel can be increased, and the rotation speed can be quickly converged to the idling rotation speed while avoiding a drop in the rotation speed.
[0101]
In each of the second and third inventions, although the dynamic engine model is not used, the air amount is increased in advance in anticipation of the dynamic delay before the engine speed falls to the idle speed. It is possible to compensate for a dynamic delay from the operation of until the engine torque rises. No.9,10In each of the inventions, although the dynamic engine model is not used, the amount of fuel per combustion is increased in advance in anticipation of a dynamic delay before the engine speed falls to the idle speed, so It is possible to compensate for a dynamic delay from the operation of the supplied fuel amount to the rise of the engine torque.
[0102]
2nd, 3rd, 3rd9,10In each of the inventions described above, the present invention can be realized even when the dynamic engine model is not well understood, and the amount of calculation is small because the digital filter calculation is unnecessary. Third, third10Each of the inventions has another merit that it is not necessary to have a map in the ROM.
Further, in each of the first, second, and third inventions, it is assumed that the throttle valve is in the fully closed position, the descent rate of the engine speed is equal to or higher than a predetermined value, and that the descent rate continues as it is, the time until the idle speed is reached. It is determined that the correction of the supplied air amount is started when the predicted arrival time is within a predetermined time. In the eighth, ninth, and tenth inventions, the throttle valve is in the fully closed position and the engine speed is not increased. The descent rate is equal to or more than a predetermined value and the descent rate is assumed to continue as it is, and the time until the engine reaches the idle speed is predicted. When the predicted arrival time is within the predetermined time, the amount of fuel supplied per combustion is estimated. Is determined to start, the engine torque when the engine speed reaches the idle speed can be made close to the required engine torque during idling with good tracking.
[0103]
4th and 4th11In each of the inventions, the required engine torque at the time of idling is set according to at least one of the auxiliary load acting on the engine at the time of idling, the target rotation speed at the time of idling, and the cooling water temperature. Regardless of whether the target engine speed is high or low, whether the cooling water temperature is high or low, or whether the auxiliary equipment load is operating or not operating during idling, there is no excess or deficiency in the amount of supplied air or supplied fuel, thereby deteriorating the driving feeling. Nothing.
[0105]
The engine rotation speed detected based on the signal from the rotation speed detection means includes noise due to a processing error of the rotation speed detection means and the like, and the estimated arrival time calculated based on the engine rotation speed is a noise. And fluctuates in the vicinity of the true value, especially when the predicted arrival time fluctuates in the vicinity of the predetermined time.1, 2nd, 3rd, 4th, 5thIn each invention of the above, the correction judgment output of the supplied airEighth, ninth, tenth, eleventh, twelfthIn each of the inventions described above, unnecessary chattering may occur in the correction determination output of the supplied fuel amount per combustion.14The value after performing the backlash characteristic processing on the estimated arrival time according to the invention ofFifteenSince the value after performing the averaging process on the predicted arrival time according to the invention is a value without fluctuation, it is possible to prevent unnecessary chattering caused by fluctuation in the predicted arrival time near the predetermined time. it can.
[0106]
No.16And the second17In each of the inventions described above, the supply air amount can be reduced without a waiting time between the rotation speed control at the time of transition to the idle state and the idle speed feedback control by increasing the supply air amount or the supply fuel amount per combustion. Alternatively, the feedback control of the idle speed is performed subsequent to the rotation speed control at the time of transition to the idle state due to the increase of the supplied fuel amount per combustion, so that the engine generated torque is reduced immediately before the start of the feedback control of the idle speed. There is no excess or deficiency, thereby reducing the load on the feedback control of the idle speed, and the convergence to the target speed during idling is further improved.
[0107]
No.18According to the invention, the ignition timing is further advanced when the engine torque reaches or immediately before the engine rotation speed reaches the control start rotation speed in the idle speed feedback control, when the engine torque is lower than the required engine torque at the time of idling. By increasing the torque), it is possible to avoid a drop in the rotation speed, and to further retard the ignition timing when the engine torque when the engine rotation speed reaches the control start rotation speed is higher than the required engine torque during idling. By doing so (reducing the generated torque), it is possible to reliably avoid the rotational speed from rising.
[Brief description of the drawings]
FIG. 1 is a control system diagram of a first embodiment.
FIG. 2 is a flowchart for explaining rotation speed control when shifting to an idle state;
FIG. 3 is a flowchart for explaining detection of various state quantities.
FIG. 4 is a flowchart for explaining a calculation of a required intake pipe pressure BIDLE during idling.
FIG. 5 is a flowchart for explaining determination of correction of a supply air amount.
FIG. 6 is a flowchart for explaining a calculation of a supply air amount QALL.
FIG. 7 is a block diagram showing a dynamic engine model.
FIG. 8: Reference model output Boost m, Boost in balanced intake pipe It is a waveform diagram at the time of transition to idle state of static, supply air amount QALL, and intake pipe pressure Boost.
FIG. 9 is a waveform chart for explaining the operation of the first embodiment.
FIG. 10 is a waveform chart for explaining the operation of the first embodiment.
FIG. 11 is a flowchart illustrating a calculation of a supply air amount QALL according to the second embodiment.
FIG. 12 is a flowchart for explaining rotation speed control when shifting to an idle state in each of the third and fourth embodiments.
FIG. 13 is a flowchart for explaining calculation of a required air amount QIDLE at the time of idling in each of the third and fourth embodiments.
FIG. 14 is a flowchart illustrating a calculation of a supply air amount QALL according to a third embodiment.
FIG. 15 is a flowchart illustrating a calculation of a supply air amount QALL according to a fourth embodiment.
FIG. 16 is a flowchart illustrating a determination of correction of a supply air amount according to a fifth embodiment.
FIG. 17 is a waveform chart for explaining the backlash characteristic processing of the fifth embodiment.
FIG. 18 is an explanatory diagram of a backlash characteristic process.
FIG. 19 is an explanatory diagram of backlash characteristic processing.
FIG. 20 is a waveform chart for explaining the operation of the conventional example.
FIG. 21 is a waveform chart for explaining the operation of the conventional example.
FIG. 22 is a waveform chart for explaining the operation of the conventional example.
FIG. 23 is a waveform chart for explaining the operation of the conventional example.
FIG. 24 is a diagram corresponding to claims of the first invention.
FIG. 25 is a diagram corresponding to claims of the second invention.
FIG. 26 is a diagram corresponding to claims of the third invention.
FIG. 278It is a claim correspondence diagram of the invention of FIG.
FIG. 289It is a claim correspondence diagram of the invention of FIG.
FIG. 2910It is a claim correspondence diagram of the invention of FIG.
[Explanation of symbols]
6 Fuel injection valve
11 ECU
15 Crank angle sensor
16 Air flow meter
20 Auxiliary air valve

Claims (18)

Means for detecting the engine speed;
When shifting to the idle state, the time until the throttle valve reaches the idle speed is estimated, assuming that the throttle valve is in the fully closed position, the descent rate of the engine speed is equal to or more than a predetermined value, and the descent rate continues as it is. Means for determining to start correction of the supply air amount when the predicted time is within a predetermined time ;
When it is determined that the correction of the supply air amount is to be started, the control system that follows the reference model using a dynamic engine model that uses the supply air amount and the engine torque as input and output is used when the engine rotation speed reaches the idle rotation speed. Means for calculating the supply air amount so that the engine torque matches the required engine torque at the time of idling;
Means for supplying the supplied air amount to the engine. Means for detecting the engine speed;
When shifting to the idle state, the time until the throttle valve reaches the idle speed is estimated, assuming that the throttle valve is in the fully closed position, the descent rate of the engine speed is equal to or more than a predetermined value, and the descent rate continues as it is. Means for determining to start correction of the supply air amount when the predicted time is within a predetermined time ;
When it is determined that the correction of the supply air amount is to be started, the supply air amount necessary to constantly maintain the required engine torque during idling at the current engine rotation speed is changed to the required engine torque during idling and the engine rotation speed. Means for calculating according to the
Means for supplying the supplied air amount to the engine. Means for detecting the engine speed;
When shifting to the idle state, the time until the throttle valve reaches the idle speed is estimated, assuming that the throttle valve is in the fully closed position, the descent rate of the engine speed is equal to or more than a predetermined value, and the descent rate continues as it is. means for determining to start the correction of the amount supplied air can and becomes within the predetermined time is predicted time,
When it is determined that the correction of the supply air amount is to be started, it is necessary to constantly match the cylinder air amount per combustion at the current engine speed with the required cylinder air amount per combustion at idle. Means for calculating the supply air amount according to the required engine torque during idling;
Means for supplying the supplied air amount to the engine. 4. The engine torque required during idling according to at least one of an auxiliary load acting on the engine during idling, a target engine speed during idling, and a coolant temperature. An engine speed control device according to any one of the preceding claims. The engine speed control device according to any one of claims 1 to 4, wherein the predetermined time is given according to a dynamic delay time from an operation of the supply air amount to a rise of engine torque. . The engine speed control device according to any one of claims 1 to 4, wherein the amount corresponding to the engine torque is an intake pipe pressure. The engine speed control device according to any one of claims 2 to 4, wherein the amount corresponding to the engine torque is an air flow rate. Means for detecting the engine speed;
When shifting to the idle state, the time until the throttle valve reaches the idle speed is estimated, assuming that the throttle valve is in the fully closed position, the descent rate of the engine speed is equal to or more than a predetermined value, and the descent rate continues as it is. Means for determining to start correcting the supplied fuel amount per combustion when the predicted time is within a predetermined time ;
When it is determined that the correction of the supplied fuel amount per combustion is started, the engine rotation speed is controlled by a control method of following a reference model by using a dynamic engine model having the supplied fuel amount per combustion and the engine torque as input and output. Means for calculating the amount of fuel supplied per combustion so that the engine torque at the time of reaching the idling rotational speed matches the required engine torque at the time of idling,
Means for supplying the supplied fuel amount to the engine. Means for detecting the engine speed;
When shifting to the idle state, the time until the throttle valve reaches the idle speed is estimated, assuming that the throttle valve is in the fully closed position, the descent rate of the engine speed is equal to or more than a predetermined value, and the descent rate continues as it is. Means for determining to start correcting the supplied fuel amount per combustion when the predicted time is within a predetermined time ;
When it is determined that the correction of the supplied fuel amount per combustion is started, the required amount of supplied fuel per combustion required to constantly maintain the required engine torque during idling at the current engine speed is required. Means for calculating according to engine torque and the engine speed,
Means for supplying the amount of fuel supplied per combustion to the engine. Means for detecting the engine speed;
When shifting to the idle state, the time until the throttle valve reaches the idle speed is estimated, assuming that the throttle valve is in the fully closed position, the descent rate of the engine speed is equal to or more than a predetermined value, and the descent rate continues as it is. Means for determining to start correcting the supplied fuel amount per combustion when the predicted time is within a predetermined time ;
When it is determined that the correction of the supplied fuel amount per combustion is started, it is necessary to constantly match the fuel amount per combustion at the current engine speed with the required fuel amount per combustion at idle. Means for calculating the amount of fuel supplied per combustion according to the required engine torque during idling;
Means for supplying the amount of fuel supplied per combustion to the engine. Auxiliary load acting on the engine when idling, a target rotational speed during idling, any setting the required engine torque during the idling in accordance with at least one cooling water temperature from claim 8, wherein up to 10 An engine speed control device according to any one of the preceding claims. The engine according to any one of claims 8 to 11, wherein the predetermined time is given according to a dynamic delay time from the operation of the supplied fuel amount per combustion to the rise of the engine torque. Speed control device. The engine speed control device according to any one of claims 8 to 11, wherein an amount corresponding to the engine torque is the fuel amount per combustion. The engine speed control according to any one of claims 1, 2 , 3 , 4 , 5 , 8 , 9 , 10 , 11, and 12 , wherein a backlash characteristic process is performed on the predicted arrival time. apparatus. The engine speed control device according to any one of claims 1, 2 , 3 , 4 , 5 , 8 , 9 , 10 , 11, and 12 , wherein an averaging process is performed on the predicted arrival time. . When performing idle speed feedback control, any of claims 1 to 5 wherein the engine speed, characterized in that to terminate the correction of the supply air volume when reaching the control start rotational speed of the feedback control An engine speed control device according to any one of the preceding claims. When performing idle speed feedback control, from claim 8, characterized in that to terminate the correction of the fuel supply amount per the one combustion when the engine speed has reached the control start rotational speed of the feedback control 13. The engine speed control device according to any one of 12 to 12 . According to claim 16 or 17, characterized in that for controlling the ignition timing so that the engine torque is consistent with the required engine torque during idling immediately before the engine speed or arrival of when reaching the control start rotational speed Engine speed control device.

Images