JP2004019539A - Fuel injection control device for internal-combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To continue pilot learning control by changing each command value interval in the multi-stage injection when performing the pilot learning control if an unstable running condition of an engine is detected in the midst of performing the pilot learning control. <P>SOLUTION: If any unstable running condition of an engine, in particular, increase of combustion noise or engine vibrations is detected in the midst of performing the pilot learning control to learn and correct dispersion of the actual pilot injection to each injection command value from the correction of the pilot injection which is the learned value for each cylinder calculated by using ISC correction and FCCB correction, each command value interval in the multi-stage injection in performing the pilot learning control is changed little by little so as to realize the actual injection interval equivalent to the target value to search for the command value interval for stably running the engine, and the pilot learning control is continued without stopping the pilot learning control. <P>COPYRIGHT: (C)2004,JPO

Description

【００５２】
ここで、パイロット噴射量は無負荷燃費の１／Ｎの噴射量指令値である（Ｑｉｄｌｅ）／Ｎをベースとし、下記の数２の演算式に示したように、パイロット学習制御の実行時の多段噴射における各指令値インターバルの影響、各噴射の開始時期（タイミング）による気筒内圧の影響、燃料噴射圧力（コモンレール圧力）の影響等を考慮し、図９に示したように、Ｎ回噴射が実際に等量のパイロット噴射量となるように各噴射量指令値（ＱＰＬ１＝ＱＰＬ２＝ＱＰＬ３＝ＱＰＬ４（Ｑｍａｉｎ）＝ＱＰＬ５（Ｑｆｕｐ）＝ｔｏｔａｌＱ／Ｎ）を補正するようにしても良い。
【数２】

【００５３】
但し、Ｑｉｄｌｅはエンジン回転速度（ＮＥ）とアクセル開度（ＡＣＣＰ）と基本噴射量（Ｑ）との関係を予め実験等により測定して作成した特性マップまたは演算式より算出される適合値で、ＱＰＬＣＰＱは気筒内圧補正係数で、ＱＩＮＴはインターバル依存性補正係数である。ここで、ＱＰＬＣＰＱおよびＱＩＮＴは噴射量補正量ではなく、噴射期間補正量（インジェクタ通電パルス時間補正量）であっても良い。
【００５４】
次に、図１０に示したように、エンジン１の各気筒間の回転速度変動量差に応じて、各気筒の燃料噴射量を増減するＦＣＣＢ補正により、各気筒間の回転速度変動が平滑化するように、各気筒毎の多段噴射における１噴射当たりの各噴射量指令値に、各気筒間の回転速度変動を平滑化する方向への噴射量補正量（ＦＣＣＢ補正量：ＱＦＣＣＢ）をそれぞれ付加する（学習制御実行手段：ステップＳ４）。このとき、各気筒毎の各噴射のＦＣＣＢ補正量は、上記の無負荷燃費（Ｑｉｄｌｅ）の１／Ｎに相当するパイロット噴射量にそれぞれＱＦＣＣＢ／Ｎずつ反映させる。
【００５５】
次に、同じく、図１０に示したように、各気筒毎の平均エンジン回転速度を目標回転速度（目標アイドル回転速度）に合わせるために、全気筒一律にＩＳＣ補正を行ない、各気筒毎の各噴射のＦＣＣＢ補正量（ＱＦＣＣＢ／Ｎ）に、目標回転速度に合わせるための噴射量補正量（ＩＳＣ補正量：ＱＩＳＣ）を全気筒一律に付加する（学習制御実行手段：ステップＳ５）。このとき、ＩＳＣ補正量は、上記の無負荷燃費（Ｑｉｄｌｅ）の１／Ｎに相当するパイロット噴射量と各気筒毎の各噴射のＦＣＣＢ補正量（ＱＦＣＣＢ／Ｎ）とを加算した値にＱＩＳＣ／Ｎを全気筒一律に反映させる。なお、ＩＳＣ補正は、例えば５０〜７０ｍｓｅｃ間隔で１ｍｍ^３／ｓｔずつ全気筒に一律に付加して所定時間またはＩＳＣ補正量（ＱＩＳＣ）が安定するまで、つまり平均エンジン回転速度が目標回転速度に略一致するまで継続して実行される。
【００５６】
次に、上記のパイロット学習制御の実行途中で、つまりステップＳ３、ステップＳ４およびステップＳ５の途中で、エンジン１の運転状態が不安定な運転状態であるか否かを判定する（ステップＳ６）。この判定結果がＮＯの場合、つまりエンジン１の運転状態が安定状態の場合には、図１１に示したように、ＩＳＣ補正量およびＦＣＣＢ補正量から現在の圧力水準のコモンレール圧力での、エンジン１の各気筒毎への噴射量補正量（今回学習値）を算出する（補正量算出手段、学習値算出手段：ステップＳ７）。なお、上記の今回学習値は、ステップＳ４の各噴射毎のＦＣＣＢ補正量をマルチ噴射回数（Ｎ回）で割り算した値｛（ＱＦＣＣＢ）／Ｎ｝とステップＳ５の各噴射毎のＩＳＣ補正量をマルチ噴射回数（Ｎ回）で割り算した値｛（ＱＩＳＣ）／Ｎ｝により、下記の数３の演算式で表わされ、エンジン１の各気筒毎に、しかも予め設定された複数の異なる各圧力水準のコモンレール圧力毎に算出される。
【数３】

【００５７】
なお、今回学習値は各噴射の無負荷燃費／Ｎの噴射量指令値（ｔｏｔａｌＱ／Ｎ）に加算する、現在の圧力水準のコモンレール圧力での噴射量補正量として算出される。ここで、今回学習値は噴射量補正量ではなく、噴射期間補正量（インジェクタ通電パルス時間補正量）であっても良い。
【００５８】
次に、予め設定された複数の異なる全圧力水準のコモンレール圧力での学習値の算出が終了しているか否かを判定する。例えば１圧力水準Ｅ（ＭＰａ）のコモンレール圧力での学習値の算出が終了しているか否かを判定する（ステップＳ８）。この判定結果がＮＯの場合、すなわち、予め設定された複数の異なる全圧力水準（Ａ，Ｂ，Ｃ，Ｄ）のコモンレール圧力毎の学習値の算出が終了していない場合には、ステップＳ２の処理に進み、ステップＳ２にてエンジン１の噴射条件や吸排気条件等を変更することなく、ただ設定された先の圧力水準から次の圧力水準（例えばＡ→Ｂ，Ｂ→Ｃ，Ｃ→Ｄ，Ｄ→Ｅ）にコモンレール圧力を変更して、ステップＳ３から、再度パイロット学習制御を実行して、ＩＳＣ補正量およびＦＣＣＢ補正量から次の圧力水準のコモンレール圧力でのエンジン１の各気筒毎への学習値を算出する。
【００５９】
また、ステップＳ８の判定結果がＹＥＳの場合、つまり予め設定された複数の異なる全圧力水準のコモンレール圧力毎の学習値の算出が終了していることが確認できた場合には、ステップＳ７で算出した学習値、つまり各圧力水準のコモンレール圧力での、エンジン１の各気筒毎の各学習値を、図１２の形式の学習値マップに書き込み、各圧力水準のコモンレール圧力での、エンジン１の各気筒毎の各学習値をスタンバイＲＡＭまたはＥＥＰＲＯＭ等のメモリに記憶（バックアップ）する（学習値記憶手段：ステップＳ９）。
【００６０】
次に、格納された各圧力水準のコモンレール圧力での、エンジン１の各気筒毎の各学習値を噴射量補正量として、下記の数４の演算式に基づくパイロット噴射量の算出時に反映させる（ステップＳ１０）。その後に、図７の制御ルーチンを抜ける。
【数４】

【００６１】
但し、ＱＰＬＢは適合値（エンジン回転速度（ＮＥ）とアクセル開度（ＡＣＣＰ）と基本噴射量（Ｑ）との関係を予め実験等により測定して作成した特性マップより算出）で、ＱＩＳＣはＩＳＣ補正量で、ＫＩＳＣはＩＳＣ補正量反映係数で、ＱＫＴＨＦは燃料温度補正係数で、ＱＦＣＣＢはＦＣＣＢ補正量で、ＫＦＣＣＢはＦＣＣＢ補正量反映係数で、ＱＫＰＣは学習値圧力感度補正係数で、ＱＫＮＥは学習値エンジン回転速度感度補正係数で、ＱＰＬＣＰＱは気筒内圧補正係数で、ＱＩＮＴはインターバル依存性補正係数である。学習値は、メモリに記憶された図１２の形式の学習値マップから算出する。なお、パイロット学習制御で使用した圧力水準以外、つまり予め設定された複数の異なる全圧力水準のコモンレール圧力以外の噴射量補正量については２点補間等にて算出する。ここで、ＱＰＬＣＰＱおよびＱＩＮＴは噴射量補正量ではなく、噴射期間補正量（インジェクタ通電パルス時間補正量）であっても良い。
【００６２】
また、ステップＳ６の判定結果がＹＥＳの場合、具体的にはパイロット学習制御の実行途中で、エンジン１の各気筒毎の回転速度変動を検出し、気筒間の回転速度変動が所定時間以上経過しても平滑化しない場合、あるいはエンジン１の平均回転速度を検出し、エンジン１の平均回転速度が目標回転速度に所定時間以上経過しても略一致しない場合、あるいは多段噴射における１噴射当たりの各噴射量指令値（各パイロット噴射量）、噴射タイミング（ＴＦＩＮ）、目標燃料圧力（ＰＦＩＮ）、ＦＣＣＢ補正量の変化量、ＩＳＣ補正量の変化量が所定の範囲外の場合には、エンジン１の運転状態が不安定な運転状態であると判断して、予め設定しておいた値（Ｋ）だけ、パイロット学習制御の実行時の多段噴射における各指令値インターバルを減少させる。
【００６３】
例えば図９、図１３（ａ）および図１４（ａ）に示したパイロット学習制御の実行時の多段噴射における、ＱＰＬ１とＱＰＬ２との無噴射間隔である指令値インターバル（ＴＰＬ１ＣＲ）を、｛ＴＰＬ１ＣＲ（ｉ−１）−Ｋ｝にセットする。また、ＱＰＬ２とＱＰＬ３との無噴射間隔である指令値インターバル（ＴＰＬ２ＣＲ）を、｛ＴＰＬ２ＣＲ（ｉ−１）−Ｋ｝にセットする。また、ＱＰＬ３とＱｍａｉｎとの無噴射間隔である指令値インターバル（ＴＰＬ３ＣＲ）を、｛ＴＰＬ３ＣＲ（ｉ−１）−Ｋ｝にセットする。また、ＱｍａｉｎとＱｆｕｐとの無噴射間隔である指令値インターバル（ＴＦＵＰＣＲ）を、｛ＴＦＵＰＣＲ（ｉ−１）−Ｋ｝にセットする（無噴射間隔変更手段：ステップＳ１１）。
【００６４】
次に、インターバル最小値ガード判定を実施する。具体的には、パイロット学習制御の実行時の多段噴射における各指令値インターバルのうちの少なくとも１つの指令値インターバル（ＴＰＬ１ＣＲ）が最小値（ＫＭＩＮ）以下であるか否かを判定する（ステップＳ１２）。この判定結果がＮＯの場合には、ステップＳ３の処理に進み、ステップＳ３にてエンジン１の他の噴射条件や吸排気条件等を変更することなく、各指令値インターバルのみを変更して、ステップＳ４から再度学習制御を実行する（再学習制御実行手段）。
【００６５】
また、ステップＳ１２の判定結果がＹＥＳの場合には、パイロット学習制御の実行時の多段噴射における各指令値インターバルを少しずつ減少しても、エンジン１が安定した運転状態で運転できる各指令値インターバルを探し出すことができないと判断して、すなわち、上記のパイロット学習制御を実行してもエンジン不安定状態が所定時間以上継続していると判断して、パイロット学習制御の実行時の多段噴射における各指令値インターバルを最小値にセットして、パイロット学習制御を終了（中止または中断または禁止）する（学習制御禁止手段）。これにより、エンジン１の不安定な運転状態が長時間継続することを防止できる。このときの各気筒毎への噴射量補正量または噴射期間補正量の更新および記憶を中止または中断または禁止することにより、各気筒毎への噴射量または噴射期間の誤学習（誤補正）または過補正を防止できる。
【００６６】
［実施例の特徴］
本実施例のように、ＩＳＣ補正およびＦＣＣＢ補正を用いて算出した各気筒毎の学習値であるパイロット噴射量補正量またはパイロット噴射期間補正量から、パイロット噴射の各噴射量指令値（例えばＴＱパルス時間）に対する実際のパイロット噴射量のバラツキ、インジェクタ４の個体差、インジェクタ４の経時劣化量を学習補正するパイロット学習制御において、パイロット学習制御の実行時には、特定気筒のインジェクタ４の駆動を、エンジン１の圧縮行程中、膨張行程中に複数回実施することで、燃料噴射を複数回に分けて行なうマルチ噴射が実施されている。
【００６７】
ところが、インジェクタハードの噴射開始遅れ（ＴＤ）や噴射終了遅れ（ＴＤＥ）のばらつきにより、指令値インターバルに対して実噴射インターバルが長くなる。このように、実噴射インターバルが長くなると、パイロット噴射による火種が殆ど消失した時点で次のパイロット噴射が実施されるため、あるいはパイロット噴射による火種が殆ど消失した時点でメイン噴射が実施されるため、エンジン１の気筒内において燃料が正しく燃焼しない失火状態が発生し、エンジン１の運転状態が不安定な運転状態になる場合がある。ここで、図１３（ｂ）は、噴射終了遅れ（ＴＤＥ）が小さくなって、実インターバルが大きくなり、失火が発生している例を示した図である。また、図１４（ｂ）は、噴射開始遅れ（ＴＤ）が大きくなって、実インターバルが大きくなり、失火が発生している例を示した図である。
【００６８】
そこで、本実施例のパイロット学習制御装置においては、上記のＩＳＣ補正量とＦＣＣＢ補正量との和をパイロット噴射量とメイン噴射量とのトータルの噴射量により案分する方式で学習値を算出するパイロット学習制御の実行途中で、エンジン１の運転状態が不安定な運転状態、特に燃焼騒音の増加やエンジン振動の増加を検出した場合には、パイロット学習制御の実行時の各指令値インターバルを、図１３（ｃ）および図１４（ｃ）に示したように、狙いと同等の実噴射インターバルとなるように少しずつ小さくして、パイロット学習制御の実行中にエンジン１を安定して運転できる指令値インターバルを探し出し、上記のようなパイロット学習制御を中止または中断または禁止することなく、パイロット学習制御を継続できるようになる。なお、図１３（ｃ）および図１４（ｃ）に示したように、各噴射量指令値に対する実際のパイロット噴射量のＱ減量分は、上記のＩＳＣ補正およびＦＣＣＢ補正を用いたパイロット学習制御により補正する。
【００６９】
それによって、各噴射毎の噴射量補正量または噴射期間補正量（インジェクタ通電パルス時間補正量）の誤学習または過学習による過剰な補正を防止できるので、エンジン１の燃焼騒音やエンジン振動や排気ガス性能（排気エミッション）の悪化を防止できる。これにより、所定の学習補正頻度によってパイロット学習制御を実行するものにおいても、次回の学習値の算出までの間、狙い通りのパイロット噴射量またはパイロット噴射期間となるので、上記のパイロット噴射の効果を十分に発揮でき、燃焼騒音やエンジン振動、更には排気ガス性能等のエンジン性能が悪化することはない。
【００７０】
また、アイドル運転でのコモンレール圧力に限定した噴射量補正量または噴射期間補正量（インジェクタ通電パルス時間補正量）ではなく、複数の異なるコモンレール圧力でのパイロット噴射期間（噴射量指令値）に対する実際のパイロット噴射量のバラツキ、インジェクタ４の個体差、インジェクタ４の経時劣化量に対応した噴射量補正量または噴射期間補正量を各気筒毎に算出することにより、通常のエンジン運転時の広い運転領域に渡って各学習値を反映させることができる。これにより、エンジン１の全運転領域に亙って、理想的なパイロット噴射期間（噴射量指令値）とパイロット噴射量との相関が得られるようになる。
【００７１】
また、予め設定された全圧力水準Ａ、Ｂ、Ｃ、Ｄ、Ｅ以外のコモンレール圧力に関しては２点補間等を行なうことにより、パイロット学習制御の実行時のコモンレール圧力以外のコモンレール圧力を含め実車におけるコモンレール圧力の使用領域全域で、メモリに記憶された学習値を噴射量補正量または噴射期間補正量としてパイロット噴射量（ＱＰＩＬＯＴ）またはパイロット噴射期間（噴射量指令値：ＴＱＰＩＬＯＴ）の算出に反映させることができる。これにより、常に、理想的なパイロット噴射期間（噴射量指令値）とパイロット噴射量との相関が得られるようになる。
【００７２】
［変形例］
本実施例では、本発明をパイロット学習制御装置を備えたコモンレール式燃料噴射システムに適用した例を示したが、本発明をコモンレールを備えず、電子制御方式の分配型燃料噴射ポンプまたは電子制御方式の列型燃料噴射ポンプ等を備えた内燃機関用噴射量制御装置に適用しても良い。また、本実施例では、電磁式燃料噴射弁よりなるインジェクタ４を用いた例を説明したが、圧電方式の燃料噴射弁よりなるインジェクタを用いても良い。また、メイン噴射に先立って行なわれるパイロット噴射（プレ噴射とも言う）の回数は、１回以上任意に設定しても良く、また、メイン噴射の後に行なわれるパイロット噴射（アフター噴射とも言う）の回数も、０回または１回以上任意に設定しても良い。
【００７３】
本実施例では、図７の制御ルーチンのステップＳ３に示す分割噴射を正確に均等にＮ回に分割する均等分割噴射としたが、これは必ずしも正確に均等にＮ回に分割する均等分割噴射に限定しなくても良い。あるいは、Ｎ回均等分割噴射を、例えばｔｏｔａｌＱ＝５ｍｍ^３／ｓｔの場合、１ｍｍ^３／ｓｔ、１ｍｍ^３／ｓｔ、１ｍｍ^３／ｓｔ、２ｍｍ^３／ｓｔの４回に略均等に分割噴射し、ＦＣＣＢ補正量、ＩＳＣ補正量の各噴射への反映を分割方法に応じて適切に（例えば１：１：１：２の比例配分または各々１／４等）反映し、図７の制御ルーチンのステップＳ７に示す学習値の算出を行なっても良い。以上のような方法で本発明を実施しても、概ね上記実施例と同等の効果を達成することができる。
【００７４】
本実施例では、エンジン１の各気筒毎への噴射量補正量または噴射期間補正量を更新して記憶する補正量記憶手段としてスタンバイＲＡＭまたはＥＥＰＲＯＭを用いたが、スタンバイＲＡＭまたはＥＥＰＲＯＭを用いずに、ＥＰＲＯＭ、フラッシュ・メモリ等の不揮発性メモリ、ＤＶＤ−ＲＯＭ、ＣＤ−ＲＯＭ、あるいはフレキシブル・ディスクのような他の記憶媒体を用いて、前回または今回のパイロット学習制御により更新した前回学習値または今回学習値を記憶するようにしても良い。この場合にも、イグニッションスイッチをオフ（ＩＧ・ＯＦＦ）した後、あるいはエンジンキーをキーシリンダより抜いた後も、記憶した内容は保存される。
【００７５】
また、上記のパイロット学習制御によってＦＣＣＢ補正量が所定値以上の場合、あるいはＩＳＣ補正量が所定値以上の場合、あるいはトータルの学習量が所定値以上の場合、あるいは前回学習値と今回学習値との差が所定の範囲外の場合には、噴射量指令値に対して所定値以上の噴射量バラツキがあることを検出できるので、インジェクタ単品個々の故障も検出できる。この場合には、異常警告ランプ（インジケータランプ）を点灯して運転者にインジェクタ４の交換を促すようにしても良い。また、上記のパイロット学習制御をアイドル運転またはアイドル安定状態での目標燃料圧力に限定して実行しても良い。また、上記のパイロット学習制御を一定または可変の学習補正頻度（例えば走行距離等）にて実行できるようにしても良い。
【図面の簡単な説明】
【図１】コモンレール式燃料噴射システムの全体構成を示した概略図である（実施例）。
【図２】基本噴射量を算出するための特性図である（実施例）。
【図３】噴射指令パルス時間を算出するための特性図である（実施例）。
【図４】インジェクタ噴射指令パルス（ＴＱパルス）、インジェクタ駆動電流波形および燃料噴射率を示したタイミングチャートである（実施例）。
【図５】パイロット噴射量を算出するための特性図である（実施例）。
【図６】パイロットインターバルを算出するための特性図である（実施例）。
【図７】パイロット学習制御方法を示したフローチャートである（実施例）。
【図８】均等分割噴射の噴射パターンを示した説明図である（実施例）。
【図９】噴射挙動および制御内容概要を示したモデル図である（実施例）。
【図１０】噴射挙動および制御内容概要を示したモデル図である（実施例）。
【図１１】噴射挙動および制御内容概要を示したモデル図である（実施例）。
【図１２】学習値マップを示した図である（実施例）。
【図１３】（ａ）は狙いの噴射パターンを示した動作説明図で、（ｂ）は噴射終了遅れが小さくなって失火が発生している例を示した動作説明図で、（ｃ）は補正実施後の噴射パターンを示した動作説明図である（実施例）。
【図１４】（ａ）は狙いの噴射パターンを示した動作説明図で、（ｂ）は噴射開始遅れが大きくなって失火が発生している例を示した動作説明図で、（ｃ）は補正実施後の噴射パターンを示した動作説明図である（実施例）。
【符号の説明】
１　エンジン（内燃機関）
２　コモンレール（蓄圧容器）
３　サプライポンプ（燃料供給ポンプ）
４　インジェクタ（電磁式燃料噴射弁）
１０　ＥＣＵ（無噴射間隔決定手段、学習制御実行手段、無噴射間隔変更手段、再学習制御実行手段、学習制御禁止手段）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention performs one or more pilot injections prior to a main injection by driving an injector mounted corresponding to a specific cylinder of an internal combustion engine a plurality of times during a compression stroke and an expansion stroke of the internal combustion engine. The present invention relates to a fuel injection control device for an internal combustion engine capable of performing an actual pilot injection amount command value for a pilot injection amount command value from a pilot injection amount correction amount or a pilot injection period correction amount. The present invention relates to a pilot learning control device that learns and corrects a variation in an injection amount and a deterioration amount of an injector over time.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a fuel injection device for a diesel engine, a pressure-accumulation type fuel injection system for injecting high-pressure fuel accumulated in a common rail into each cylinder of an engine has been known. In such a pressure-accumulation type fuel injection system, the main injection (which can be an engine torque) is performed for the purpose of performing stable combustion from the start of the main injection to reduce combustion noise and engine vibration and further improve exhaust gas performance. Prior to the main injection), a plurality of minute preliminary injections (pilot injections) are performed.
[0003]
Here, the control of the injection amount to each cylinder of the engine is usually performed by a command calculated from a command injection amount set according to the operating state or operating condition of the engine and a fuel injection pressure (common rail pressure) detected by a sensor or the like. This is performed by determining the injector drive current value applied to the solenoid valve of the injector according to the injection period (injection command pulse time, TQ pulse width).
[0004]
[Problems to be solved by the invention]
However, in general, the injection amount control for each cylinder of the engine is performed by controlling the variation of the actual injection amount with respect to the command injection period (injection command pulse time, TQ pulse width) applied to the solenoid valve of the injector. The pilot injection is mainly 5mm ³ / St or less, the pilot injection may be lost due to variations in the actual injection amount with respect to the injection command pulse time, deterioration of the injector performance (function) (deterioration of the injector over time) due to a change over time in the injection amount, or the like. However, there is a problem that the effect of the above-described pilot injection cannot be sufficiently exerted due to being too large.
[0005]
To solve these problems, the rotational speed fluctuation of each cylinder of the engine is detected and compared with the average value of the rotational speed fluctuations of all the cylinders, and the rotational speed fluctuation between the cylinders is smoothed according to the comparison result. In addition, the correction amount of the injection amount or the injection period correction amount for each cylinder of the engine is updated and stored, and the rotational speed fluctuation inter-cylinder injection amount correction (FCCB correction) is compared, and the average rotation speed of the engine is compared with the target rotation speed. Then, using an average rotation speed correction (ISC correction) that updates and stores the injection amount correction amount or the injection period correction amount for each cylinder of the engine so that the target rotation speed is obtained according to the comparison result, A pilot learning control device that corrects and learns the variation of the actual injection amount with respect to the injection command pulse time and the deterioration amount of the injector over time can be considered.
[0006]
However, the pilot learning control using the above ISC correction and FCCB correction is performed by driving the injector mounted corresponding to the specific cylinder of the engine a plurality of times during the compression stroke and the expansion stroke of the engine. The multi-injection in which the pilot injection is performed a plurality of times before the main injection is performed, but the actual injection interval (no injection interval) is long due to the variation of the injection start delay (TD) and the injection end delay (TDE) of the injector hardware. In this case, the next pilot injection is performed when the pilot injection has almost disappeared, or the main injection is performed when the pilot injection has almost disappeared, so that the fuel is correctly burned in the cylinder of the engine. In some cases, a misfiring condition occurred and the engine became unstable.
[0007]
In such a case, it is desirable to stop the pilot learning control so as not to erroneously learn the injection amount correction amount or the injection period correction amount for each cylinder of the engine, but at a predetermined learning correction frequency, When the injection amount correction amount or injection period correction amount for each cylinder of the engine is updated, the state where the pilot injection amount does not become the intended amount continues until the next update, that is, pilot injection disappears or However, if it becomes too large, the effect of the pilot injection described above cannot be sufficiently exerted, causing a problem that engine performance such as combustion noise, engine vibration, and exhaust gas performance deteriorates.
[0008]
[Object of the invention]
An object of the present invention is to allow learning control to be continued by changing each non-injection interval during execution of learning control when detecting an unstable operating state of the internal combustion engine during execution of learning control. With the goal.
[0009]
[Means for Solving the Problems]
According to the first aspect of the present invention, the learning control for updating the injection amount correction amount or the injection period correction amount for each cylinder of the internal combustion engine while performing the multi-stage injection in which the fuel injection is divided into a plurality of times is performed. During the execution, if the operating state of the internal combustion engine becomes unstable due to the occurrence of a misfire state in which the fuel does not burn properly in the cylinder of the internal combustion engine, etc. After changing the no-injection interval, the learning control is executed again while performing the multi-stage injection.
[0010]
This makes it possible to find out each non-injection interval in the multi-stage injection that can operate the internal combustion engine in a stable operation state, so that the learning control can be continued without stopping, interrupting, or prohibiting the learning control. become. Therefore, until the next learning control is executed, the state where the injection amount correction amount or the injection period correction amount does not become the intended amount continues, for example, the pilot injection disappears or becomes excessively large. It is possible to solve the problem that the engine performance such as the engine vibration and the exhaust gas performance is deteriorated.
[0011]
According to the second aspect of the present invention, the unstable operation state of the internal combustion engine continues for a predetermined time or more even when the learning control is executed again by changing each non-injection interval in the multi-stage injection at the time of executing the learning control. When the learning control is performed, the non-injection interval in the multi-stage injection during the execution of the learning control is set to the minimum value, and the learning control is stopped or interrupted or prohibited, so that the unstable operation state of the internal combustion engine continues for a long time. Can be prevented. At this time, the update and the storage of the correction amount of the injection amount or the correction amount of the injection period for each cylinder of the internal combustion engine are stopped, interrupted, or prohibited, thereby erroneously learning the injection amount or the injection period for each cylinder of the internal combustion engine. (Erroneous correction) or overcorrection can be prevented.
[0012]
According to the invention described in claim 3, the rotation speed fluctuation of each cylinder of the internal combustion engine is detected, and the detected value of the rotation speed fluctuation of each cylinder is compared with the average value of the rotation speed fluctuations of all the cylinders. By updating and storing the injection amount correction amount or the injection period correction amount for each cylinder of the internal combustion engine so that the rotational speed fluctuation between the cylinders is smoothed according to the comparison result, the command injection amount or the command It is possible to correct and learn the variation of the actual injection amount with respect to the injection period, and the aging deterioration amount of the injector for each cylinder.
[0013]
According to the invention described in claim 4, the average rotation speed of the internal combustion engine is detected, the average rotation speed of the internal combustion engine is compared with the target rotation speed, and the target rotation speed is set according to the comparison result. By updating and storing the injection amount correction amount or the injection period correction amount for each cylinder of the internal combustion engine, the variation of the actual injection amount with respect to the command injection amount or the command injection period, and the aging deterioration amount of the injectors of all cylinders Can be corrected and learned.
[0014]
According to the fifth aspect of the present invention, during the execution of the learning control, when the combustion noise or vibration of the internal combustion engine is equal to or more than a predetermined value, or the rotation speed fluctuation of each cylinder of the internal combustion engine is detected, When the rotation speed fluctuation is not smoothed after a predetermined time or more, or when the average rotation speed of the internal combustion engine is detected and the average rotation speed of the internal combustion engine does not substantially match the target rotation speed for a predetermined time or more, Alternatively, it may be detected that the operation state of the internal combustion engine is an unstable operation state. Further, according to the invention, during the execution of the learning control, each injection amount command value per one injection in the multi-stage injection, the command injection timing, the target fuel pressure, and the injection into each cylinder of the internal combustion engine. When the change amount of the amount correction amount or the injection period correction amount is out of the predetermined range, it may be detected that the operation state of the internal combustion engine is an unstable operation state.
[0015]
According to the invention described in claim 7, by driving the injector mounted corresponding to the specific cylinder of the internal combustion engine a plurality of times during the compression stroke and the expansion stroke of the internal combustion engine, a plurality of fuel injections are performed. As the multi-stage injection performed separately, multiple injections that perform one or more pilot injections before the main injection may be used, or multiple injections that perform one or more after injections after the main injection may be used. good.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
[Configuration of Example]
Embodiments of the present invention will be described based on examples with reference to the drawings. Here, FIG. 1 is a diagram showing an entire configuration of a common rail type fuel injection system.
[0017]
The common rail fuel injection system according to the present embodiment includes a common rail 2 serving as a pressure accumulator for accumulating high pressure fuel corresponding to a fuel injection pressure supplied to each cylinder of an internal combustion engine (hereinafter referred to as an engine) 1 such as a four-cylinder diesel engine. A supply pump 3 serving as a fuel supply pump for pressurizing the sucked fuel and feeding the compressed fuel into the common rail 2; and a plurality of fuel pumps for injecting high-pressure fuel accumulated in the common rail 2 into each cylinder of the engine 1 (this example). 4), and an electronic control unit (hereinafter referred to as ECU) 10 for electronically controlling the supply pump 3 and the plurality of injectors 4.
[0018]
An intake port of each cylinder (cylinder) of the engine 1 is opened and closed by an intake valve (intake valve) 11, and an exhaust port is opened and closed by an exhaust valve (exhaust valve) 12. In each cylinder, a piston 13 connected to a crankshaft (not shown) via a connecting rod is slidably provided. A radiator 14 is provided in an engine room (not shown) in which the engine 1 is housed, where the wind is easily received. The radiator 14 is provided with a cooling water temperature sensor 37 that detects the temperature of cooling water for cooling the engine 1 (engine cooling water temperature).
[0019]
Here, during the operation of the engine 1, the exhaust gas burned in the cylinder passes through the exhaust pipe 15, becomes a driving source of a variable diameter turbo (VGT) 16 turbine, and then becomes a catalyst (not shown). And discharged through a muffler (not shown). The control of the VGT 16 is performed based on signals from the intake pressure sensor, the supercharging pressure sensor 44, and the VGT position sensor 47. The supercharged (compressed) intake air having a high temperature is cooled by the intercooler 18 and then introduced into the cylinder via the intake port of the engine 1.
[0020]
Further, an intake throttle valve (throttle valve) 19 for adjusting the amount of intake air (intake amount) supplied to the engine 1 by opening and closing the intake passage in the intake pipe 17 is provided in the middle of the intake pipe 17. The opening degree of the throttle valve 19 is adjusted by an actuator 20 which operates according to a signal from the ECU 10. The actuator 20 is provided with a throttle position sensor (not shown) for detecting the opening of the throttle valve 19. As the throttle position sensor, a sensor that senses the valve opening of the throttle valve 19 separately at the time of full idling and at the time of a high load close to full opening and transmits the same to the ECU 10 may be used.
[0021]
In the vicinity of the intake port of the intake pipe 17, an eddy current control valve (swirl control valve: hereinafter referred to as SCV) 21 which is activated by a signal from the ECU 10 is provided. The SCV 21 is installed in a bypass 23 that bypasses the intake passage 22 in which the intake air temperature sensor 45 is installed, and is turned off (OFF) at low load to close the valve, and is turned on (ON) at high load to open the valve. I do.
[0022]
Further, an exhaust gas recirculation pipe 24 for guiding a part of the exhaust gas (exhaust gas recirculation gas: EGR gas) of the exhaust gas flowing through the exhaust pipe 15 to the intake pipe 17 is connected to the intake pipe 17 of this embodiment. . A valve (EGR valve) 25 for an exhaust gas recirculation device is installed at the junction of the intake pipe 17 and the exhaust gas recirculation pipe 24. Therefore, in order to reduce the amount of nitrogen oxides (NOx) generated, the intake air sucked into the cylinder opens the EGR valve 25 so that the exhaust gas recirculation amount is set for each operating state of the engine 1. The degree is controlled and mixed with the exhaust gas from the exhaust pipe 15. The exhaust gas recirculation amount (EGR amount) is determined by the intake air amount sensor 43, the intake air temperature sensor 45, and the exhaust O ₂ Feedback control is performed based on signals from the sensor 48 and the EGR position sensor 46 so that a predetermined value can be maintained.
[0023]
It is necessary that the high pressure fuel corresponding to the fuel injection pressure is continuously accumulated in the common rail 2, and the high pressure fuel accumulated in the common rail 2 is supplied from the supply pump 3 through the high pressure pipe 26. . In addition, a pressure limiter 27 for releasing pressure is attached to a relief pipe (not shown) for relieving fuel from the common rail 2 to the fuel tank so that the fuel injection pressure does not exceed the limit set pressure. . Further, a fuel pressure (also referred to as a common rail pressure) corresponding to the fuel injection pressure accumulated in the common rail 2 is measured by a fuel pressure detecting means such as the fuel pressure sensor 30.
[0024]
The supply pump 3 includes a feed pump (not shown) for pumping fuel from a fuel tank (not shown), and an electromagnetic valve (for example, a suction metering valve) for adjusting the amount of high-pressure fuel to be sent (discharged) to the common rail 2. Is a high-pressure supply pump having a built-in actuator (not shown). A fuel temperature sensor 36 for detecting the temperature of the fuel sucked from the fuel tank is provided in the supply pump 3.
[0025]
The injector 4 is attached to a cylinder block of the engine 1 (corresponding to each of the cylinders # 1 to # 4), and injects high-pressure fuel into a cylinder of each cylinder. The electromagnetic fuel injection valve includes an actuator such as an electromagnetic valve that drives the needle in the valve opening direction, and an urging unit such as a spring that urges the nozzle needle in the valve closing direction. Fuel injection from the injectors 4 to the engine 1 is performed, for example, by injecting high-pressure fuel accumulated in the common rail 2 into each cylinder of the engine 1 while the solenoid valve is open. Here, the leak fuel from the injector 4 or the fuel (return fuel) discharged from the back pressure control chamber of the nozzle needle is returned to the fuel tank via a fuel return path. Note that the longer the valve opening time (fuel injection period) of the nozzle needle of the injector 4 is, the larger the fuel injection amount injected into each cylinder of the engine 1 is.
[0026]
The ECU 10 includes a CPU that performs control processing and arithmetic processing, a storage device (a memory such as a ROM, a standby RAM or an EEPROM, and a RAM) that stores various programs and data, an input circuit, an output circuit, a power supply circuit, an injector drive circuit, and a pump. A microcomputer having a well-known structure including functions such as a driving circuit is provided. A voltage signal from the fuel pressure sensor 30 and a sensor signal from various other sensors are A / D-converted by an A / D converter, and then input to a microcomputer built in the ECU 10. Have been. Further, after the engine 1 is cranked, the engine key is returned to the IG position, and when an ignition switch (not shown) is turned on (ON), based on the control program stored in the memory, for example, the supply pump 3 The actuator of each control component such as the injector 4 is electronically controlled.
[0027]
Here, the cylinder discriminating means of this embodiment includes a signal rotor (for example, a rotating body that rotates once while the crankshaft rotates twice) 31 corresponding to the camshaft of the engine 1 and an outer periphery of the signal rotor 31. And a cylinder discriminating sensor (electromagnetic pickup) 32 that generates a cylinder discriminating signal pulse (G) based on the approach and separation of the cylinder teeth. . The rotation speed detecting means of the present embodiment includes a signal rotor (for example, a rotating body that makes one rotation while the crankshaft makes one rotation) 33 that rotates in accordance with the crankshaft of the engine 1, and an outer periphery of the signal rotor 33. And a crank angle sensor (electromagnetic pickup) 34 that generates a NE signal pulse when the teeth approach and separate from each other. The crank angle sensor 34 outputs a plurality of NE signal pulses while the signal rotor 33 makes one rotation (the crankshaft makes one rotation). The specific NE signal pulse corresponds to the position of the top dead center (TDC) of the piston of each of the # 1 to # 4 cylinders. Then, the ECU 10 detects the engine rotation speed (NE) by measuring the interval time between NE signal pulses.
[0028]
Then, the ECU 10 calculates an optimum fuel injection pressure (= common rail pressure) according to the operating state or operating condition of the engine 1, and controls a discharge amount control unit that drives an electromagnetic valve of the supply pump 3 via a pump driving circuit. Have. That is, the ECU 10 calculates the target fuel pressure (PFIN) according to the engine rotation speed (NE) and the command injection amount (QFIN), and in order to achieve the target fuel pressure (PFIN), A pump drive signal (drive current value) to the valve is adjusted to control the amount of pumped fuel (pump discharge) discharged from the supply pump 3. More preferably, in order to improve the control accuracy of the fuel injection amount, the fuel pressure (common rail pressure: NPC) in the common rail 2 detected by the fuel pressure sensor 30 depends on the operating state or operating condition of the engine 1. It is desirable to feedback-control a pump drive signal to the solenoid valve of the supply pump 3 so as to substantially match the set target fuel pressure (PFIN).
[0029]
The ECU 10 corresponds to an internal combustion engine injection amount control device that individually controls the fuel injection amount injected from the injector 4 of each cylinder. This is based on the engine rotation speed (NE), the accelerator opening (ACCP), and a characteristic map (not shown) prepared in advance through experiments and the like, to determine the optimal command injection timing (main injection start timing, hereinafter referred to as injection timing). The optimum basic injection amount is determined by an injection timing determining means for calculating TFIN, an engine rotation speed (NE), an accelerator opening (ACCP), and a characteristic map (see FIG. 2) created by experiments in advance. The basic injection amount determining means for calculating (Q), the basic injection amount (Q), the fuel temperature (THF) detected by the fuel temperature sensor 36, the engine cooling water temperature (THW) detected by the cooling water temperature sensor 37, etc. Injection amount determining means for calculating a command injection amount (QFIN) in consideration of an injection amount correction amount in consideration of the following, common rail pressure (NPC) and command injection An injection period determining means for calculating a command injection period (injection command pulse time, injector energizing pulse time: TQ) from (QFIN) and a characteristic map (see FIG. 3) created by experiments in advance, and an injector drive circuit ( Injector drive means for applying a pulse-like injector drive current (injector injection command pulse, TQ pulse, injection drive signal) to the solenoid valve of the injector 4 of each cylinder via an EDU. Here, FIG. 4 shows the injection command pulse time (= injection command value: TQ) of a specific cylinder (for example, # 1 cylinder), and the electromagnetic force of the injector 4 of the specific cylinder (for example, # 1 cylinder) corresponding to this injection command pulse time. 5 is a timing chart showing an injector driving current waveform output to a valve and a fuel injection rate of a specific cylinder (for example, # 1 cylinder).
[0030]
Here, in the present embodiment, a basic injection amount (Q) is used by using a rotation speed detecting means such as a crank angle sensor 34 and an accelerator opening sensor 35 as an operating state detecting means for detecting the operating state or operating condition of the engine 1. , The fuel injection timing (TFIN) and the target fuel pressure (PFIN) are calculated, but the common rail pressure (NPC) detected by the fuel pressure sensor 30 or other sensors (for example, fuel Temperature sensor 36, cooling water temperature sensor 37, fuel leak temperature sensor 38, oil temperature sensor 39, idle accelerator position sensor 40, atmospheric pressure sensor 41, atmospheric temperature (outside air temperature) sensor 42, intake air amount sensor 43, supercharging pressure sensor 44, intake air temperature sensor 45, EGR position sensor 46, VGT position sensor 47, exhaust O ₂ The basic injection amount (Q) or the command injection amount (Q) taking into account detection signals (engine operation information) from the sensor 48, the exhaust temperature sensor 49, the exhaust pressure sensor 50, the throttle position sensor, the intake pressure sensor, the injection timing sensor, etc.). QFIN), the injection timing (TFIN), and the target fuel pressure (PFIN) may be corrected.
[0031]
When the engine key is inserted into the cylinder and turned to the ST position, the ECU 10 is connected to a starter energizing circuit that turns on the starter switch and energizes the starter. The ECU 10 also includes a signal indicating a gear position of a transmission driven by the engine 1, a signal detecting that a driver (driver) has depressed a clutch pedal, an energization signal to a starter, a vehicle speed signal from a vehicle speed sensor, Detects vehicle information such as electromagnetic clutches for air conditioners, electric fans for condensers of air conditioners, fans for air blowers in air conditioners, electric loads for radiators, electric fans and headlights, and drive loads for air conditioner compressors, power steering, oil pumps, etc. Is configured to be input.
[0032]
Here, in the common rail fuel injection system of the present embodiment, during one cycle of the engine 1 (one stroke: intake stroke-compression stroke-expansion stroke (explosion stroke) -exhaust stroke) in the injector 4 of a specific cylinder of the engine 1. That is, it is possible to perform the multi-stage injection in which the fuel is divided into a plurality of injections while the crankshaft of the engine 1 rotates twice (720 ° CA), particularly during one combustion stroke of each cylinder of the engine 1. For example, by performing a plurality of driving of the injectors 4 during the compression stroke and the expansion stroke of the engine 1, multiple injections in which pilot injections are performed multiple times before main injection, or multiple injections after main injection are performed. Multi-injection or multi-injection in which one or more pilot injections are performed before the main injection and one or more after injections are performed after the main injection are possible.
[0033]
Therefore, the ECU 10 calculates each injection amount in the multi-injection according to the operating state or operating condition of the engine 1. More specifically, a pilot injection amount determination for calculating a pilot injection amount (QPILOT) from the engine rotation speed (NE), the command injection amount (QFIN), and a characteristic map (see FIG. 5) created by performing experiments and the like in advance. And main injection amount determining means for calculating the main injection amount (QMAIN) by subtracting the pilot injection amount (QPILOT) from the total injection amount (totalQ).
[0034]
Further, the ECU 10 determines whether there is a difference between the pilot injection and the main injection in the multi-injection based on the engine speed (NE), the command injection amount (QFIN), and a characteristic map (see FIG. 6) created by performing experiments and the like in advance. A non-injection interval determining means for calculating an injection interval (pilot interval, command interval: TINT), and a characteristic map (not shown) prepared by previously measuring an engine speed (NE), a pilot injection amount (QPILOT), and an experiment or the like. ) To calculate a non-injection interval between the pilot injections in the multi-injection.
[0035]
Further, the ECU 10 calculates a pilot injection period (injection amount command value: TQPILOT) from a pilot injection amount (QPILOT), a common rail pressure (NPC), and a characteristic map (not shown) created by measuring in advance through experiments or the like. The main injection period (injection amount command value: TQMAIN) is determined from pilot injection period determining means, a main injection amount (QMAIN), a common rail pressure (NPC), and a characteristic map (not shown) created by measuring in advance by experiments or the like. And a main injection period determining means for calculating.
[0036]
Here, the ECU 10 of the present embodiment determines the rotational speed fluctuation of each cylinder of the engine 1 for each explosion stroke during the idling operation of the engine 1 (idle stable state) or the execution of the pilot learning control (establishment of the pilot learning execution condition). The engine 1 compares the detected value of the rotational speed fluctuation of each cylinder of the engine 1 with the average value of the rotational speed fluctuations of all the cylinders, and smoothes the rotational speed fluctuation between the cylinders of the engine 1. The engine is configured to execute a rotational speed fluctuation inter-cylinder injection amount correction (FCCB correction) for individually adjusting an optimum injection amount for each cylinder.
[0037]
Specifically, by calculating the interval time of the NE signal pulse taken from the crank angle sensor 34, the instantaneous rotation speed of each cylinder of the engine 1 for each explosion stroke is calculated, and the BTDC 90 ° CA to ATDC 90 ° CA The maximum value of the interval time between NE signal pulses is read as the minimum rotation speed (Nl) of the instantaneous rotation speed of the cylinder. Further, the minimum value of the interval time between NE signal pulses between BTDC 90 ° CA and ATDC 90 ° CA is read as the maximum rotation speed (Nh) of the instantaneous rotation speed of the cylinder. However, Nl and Nh do not necessarily need to be the minimum rotation speed and the maximum rotation speed, and may be a low rotation speed and a high rotation speed that represent rotation speed fluctuations of the cylinder.
[0038]
After these calculations are performed for each cylinder, a cylinder rotation speed difference (ΔNk) between the maximum rotation speed (Nh) for each cylinder and the minimum rotation speed (Nl) for each cylinder is calculated. Thereby, the detected value of the rotational speed fluctuation for each cylinder of the engine 1 is calculated. Then, an average value (ΣΔNk) of the rotational speed fluctuations of all the cylinders of the engine 1 is calculated. That is, after averaging the rotational speed fluctuations of all the cylinders of the engine 1 and calculating the average value of the rotational speed fluctuations of all the cylinders, the detected value of the rotational speed fluctuation of each cylinder and the average value of the rotational speed fluctuations of all the cylinders The deviation of the rotational speed fluctuation between the cylinders is calculated from the above. Then, the injection amount of each injection calculated for each cylinder of the engine 1 is corrected so that the rotation speed fluctuation between the cylinders is smoothed so that the rotation speed fluctuation between the cylinders is smoothed. The amount (also referred to as FCCB correction amount) or the injection period correction amount is added to each cylinder (learning control executing means).
[0039]
Further, the ECU 10 of the present embodiment adjusts the idle rotation speed (average engine rotation speed), which is the current engine rotation speed, to the target rotation speed at the time of idling operation or at the time of executing the pilot learning control (establishment of the pilot learning execution condition). For this purpose, an average rotation speed correction (ISC correction) is performed uniformly for all cylinders with respect to a deviation (ΔNE) between the idle rotation speed and the target rotation speed.
[0040]
Specifically, an average rotation speed (engine rotation speed: NE) of each cylinder of the engine 1 is compared with a target rotation speed (a target idle rotation speed, a target NE), and an injection amount correction amount corresponding to a difference between the rotation speeds. (Also referred to as an ISC correction amount) or an injection period correction amount. Then, an injection amount correction amount (also referred to as an ISC correction amount) or an injection period required to match the target rotation speed with the injection amount calculated for each cylinder so that the average rotation speed substantially matches the target rotation speed. The correction amount is uniformly added to all cylinders (learning control executing means). The ISC correction is set based on the engine speed (NE) corresponding to the idle speed, the operating state such as the engine coolant temperature (THW) and the fuel temperature (THF) or the operating conditions, and vehicle information such as electric load and drive load. It is preferable to compare the target rotation speed with the target rotation speed and to perform feedback control of the injection amount so as to reach the target rotation speed in proportion to the difference.
[0041]
[Control method of embodiment]
Next, a pilot learning control method according to the present embodiment will be briefly described with reference to FIGS. FIG. 7 is a flowchart showing a pilot learning control method. The control routine of FIG. 7 is repeated at predetermined timings after the ignition switch is turned on.
[0042]
When it is time to enter the control routine of FIG. 7, it is determined whether the pilot learning execution condition is satisfied (step S1). If the result of this determination is NO, the control routine of FIG. 7 is exited. Here, when all of the following (1) and (2) are satisfied, the pilot learning execution condition is satisfied (YES). When any one of the following (1) and (2) is not satisfied, the pilot learning is executed. The learning execution condition is not satisfied (NO).
[0043]
(1) First, it is confirmed whether or not the combustion state of the engine 1 is in the idling stable state based on signals from various sensors and switches capable of detecting the operating state or operating conditions of the engine 1 or the engine 1 attached to the vehicle. For example, the engine speed (NE) is equal to or less than a predetermined value (for example, 1000 rpm), the accelerator opening (ACCP) is equal to or less than a predetermined value (for example, 0%), and the running speed (SPD: hereinafter referred to as vehicle speed) of the vehicle is a predetermined value (for example, 0 km). / H) below, the command injection amount (QFIN) is a predetermined value (for example, ³ / St) Hereinafter, when it is detected that the gear position of the transmission is N (neutral), it can be detected that the combustion state of the engine 1 is in the idling stable state.
[0044]
(2) Next, it is confirmed that the engine load is within a predetermined range based on signals from various sensors, switches, and control command values that can detect the load state of the engine 1 or the engine 1 attached to the vehicle. Examples of these are electric fans for radiators, electric heaters, headlights, switches that can detect electric loads such as electromagnetic brakes, sensors, air conditioners, compressors such as power steering, switches that can detect pump loads, sensors and idle rotation. There is a speed change or a change amount of the ISC injection amount necessary to keep the idle rotation speed at a predetermined value.
[0045]
If the determination result of step S1 is YES, that is, if the pilot learning execution condition is satisfied, the pilot injection amount correction amount or the pilot injection period for each cylinder calculated by the following FCCB correction or ISC correction. Based on the correction amount, a pilot learning control for learning and correcting the variation of the actual pilot injection amount with respect to each injection amount command value of the pilot injection, the individual difference of the injector 4, and the deterioration amount of the injector 4 with time is executed.
[0046]
Specifically, first, in order to fix the combustion state (injection conditions, intake / exhaust conditions) of the engine 1, as shown in FIG. 8, the number of injections per injection in multi-stage injection (multi injection) (multi injection number) ) Is set to N times (5 times in this example). In addition, a target value of the common rail pressure for each of a plurality of different pressure levels is set. That is, as shown in FIG. 8, the target fuel pressure (PFIN) is first set to A (MPa). Here, in this embodiment, the target fuel pressure (PFIN) is sequentially set to B (MPa) to E (MPa).
[0047]
The target fuel pressure (PFIN) to be set, that is, the common rail pressure of a plurality of different pressure levels used when executing the pilot learning control can be arbitrarily set, and the common rail pressure is not limited to five types but is also three types. , 7 types, 10 types, etc. can be set arbitrarily. When the calculation of the injection amount correction amount (learning value) of the same pressure level is completed, the common rail pressure of the next set pressure level (for example, A → B, B → C, C → D, D → E) is reduced. Change and proceed to step S3.
[0048]
At this time, for the purpose of achieving the target fuel pressure (PFIN) as the target value of the common rail pressure, the supply is performed according to the pressure deviation between the common rail pressure (NPC) detected by the fuel pressure sensor 30 and the target fuel pressure (PFIN). The pump drive signal (drive current value) to the solenoid valve of the pump 3 is adjusted. For example, the on / off ratio (energization time / DUTY ratio) of the pump drive signal per unit time is adjusted according to the pressure deviation between the common rail pressure (NPC) and the target fuel pressure (PFIN), and the solenoid valve of the supply pump 3 is adjusted. By changing the opening of the pump, the pumping amount of fuel discharged from the supply pump 3 (pump discharge amount) is controlled so that the common rail pressure (NPC) substantially matches the target fuel pressure (PFIN). Feedback controlled. Thus, from one pressure level (the same pressure level) A corresponding to a low injection pressure in the normal idle stable state, to one pressure level (the same pressure level) corresponding to a high injection pressure different from the normal idle stable state. Up to level E, the common rail pressure will be changed.
[0049]
Further, the injection timing (TFIN) reference position of the N times (five times in this example) injection is set near TDC. Also, the target rotation speed of the ISC correction is set to 750 rpm. Further, the supercharging pressure target value, the EGR amount is not set (EGR cut), and the valve opening of the throttle valve (intake throttle valve) 19 and the valve opening of the SCV 21 are fixed. Further, each command value interval in the multi-stage injection at the time of executing the pilot learning control is fixed. For example, as shown in FIGS. 13A and 14A, the command value interval (QP1-2) is set to (TPL1CR: for example, 10 ° CA), and the command value interval (QP2-3) is set to (TPL2CR: For example, 11 ° CA), the command value interval (QP3-4) is set to (TPL3CR: for example, 12 ° CA), and the command value interval (QP4-5) is set to (TFUPCR: for example, 13 ° CA). . In this embodiment, QP4 corresponds to the main injection (non-injection interval determining means: step S2).
[0050]
Next, each injection amount command value (each pilot injection amount) per injection in multi-stage injection in which N injections are equally divided into N is calculated (step S3). Each of the injection amount command values is a characteristic map (FIG. 5) created by measuring the relationship between the engine rotational speed (NE) and the accelerator opening (ACCP) in advance by experiment, as shown in the following equation (1). 2) or a basic injection amount (Q) calculated from an arithmetic expression, and a command injection amount (TH) calculated in consideration of an injection amount correction amount in consideration of an engine coolant temperature (THW), a fuel temperature (THF), and the like. 1 / N of the total injection amount (totalQ) obtained by substantially equally dividing the QFIN) by the number of times of multi-injection (N times), for example, 1 / N of the no-load fuel consumption (Qidle) used when the operation state of the engine 1 is in the idling stable state. This is a pilot injection amount corresponding to N.
[0051]
In the present embodiment, when the operating state of the engine 1 is in the idling stable state, the total injection amount (totalQ) is 5 mm. ³ / St, and when the number of injections per injection (multiple injections) in the multi-stage injection (multi-injection) is set to five, each injection amount command value (each pilot injection amount) per injection in the multi-stage injection is 1 mm ³ / St.
(Equation 1)

[0052]
Here, the pilot injection amount is based on the injection amount command value of 1 / N of the no-load fuel consumption (Qidle) / N, and as shown in the following equation 2, the pilot injection amount at the time of execution of the pilot learning control. In consideration of the influence of each command value interval in the multi-stage injection, the influence of the cylinder pressure due to the start timing (timing) of each injection, the influence of the fuel injection pressure (common rail pressure), etc., as shown in FIG. Each of the injection amount command values (QPL1 = QPL2 = QPL3 = QPL4 (Qmain) = QPL5 (Qup) = totalQ / N) may be corrected so that the pilot injection amounts are actually equal.
(Equation 2)

[0053]
Here, Qidle is an adaptation value calculated from a characteristic map or an arithmetic expression created by previously measuring the relationship among the engine rotation speed (NE), the accelerator opening (ACCP), and the basic injection amount (Q) through experiments or the like. QPLCPQ is a cylinder pressure correction coefficient, and QINT is an interval-dependent correction coefficient. Here, QPLCPQ and QINT may be injection amount correction amounts (injector energization pulse time correction amounts) instead of injection amount correction amounts.
[0054]
Next, as shown in FIG. 10, the rotational speed fluctuation between the cylinders is smoothed by FCCB correction for increasing or decreasing the fuel injection amount of each cylinder according to the rotational speed fluctuation amount difference between the cylinders of the engine 1. In such a manner, an injection amount correction amount (FCCB correction amount: QFCCB) in a direction to smooth the rotational speed fluctuation between the cylinders is added to each injection amount command value per injection in the multi-stage injection for each cylinder. (Learning control execution means: step S4). At this time, the FCCB correction amount for each injection for each cylinder reflects QFCCB / N on the pilot injection amount corresponding to 1 / N of the no-load fuel consumption (Qidle).
[0055]
Next, similarly, as shown in FIG. 10, in order to match the average engine rotation speed of each cylinder to the target rotation speed (target idle rotation speed), ISC correction is uniformly performed for all cylinders. An injection amount correction amount (ISC correction amount: QISC) for adjusting to the target rotation speed is uniformly added to the injection FCCB correction amount (QFCCB / N) (learning control execution means: step S5). At this time, the ISC correction amount is a value obtained by adding the pilot injection amount corresponding to 1 / N of the above-mentioned no-load fuel consumption (Qidle) and the FCCB correction amount (QFCCB / N) of each injection for each cylinder to QISC / N is uniformly reflected in all cylinders. The ISC correction is performed, for example, at 1 mm intervals at 50 to 70 msec intervals. ³ / St is uniformly added to all cylinders, and is continuously executed until a predetermined time or an ISC correction amount (QISC) is stabilized, that is, until the average engine rotation speed substantially matches the target rotation speed.
[0056]
Next, during the execution of the pilot learning control, that is, during the steps S3, S4 and S5, it is determined whether or not the operating state of the engine 1 is an unstable operating state (step S6). If the result of this determination is NO, that is, if the operating state of the engine 1 is stable, as shown in FIG. 11, the engine 1 at the common rail pressure at the current pressure level is determined from the ISC correction amount and the FCCB correction amount. Is calculated (the current learning value) for each cylinder (correction amount calculating means, learning value calculating means: step S7). The above-described learning value this time is obtained by dividing the FCCB correction amount for each injection in step S4 by the number of multiple injections (N times) {(QFCCB) / N} and the ISC correction amount for each injection in step S5. A value {(QISC) / N} divided by the number of times of multi-injection (N times) is expressed by the following equation (3), and for each cylinder of the engine 1 and a plurality of different preset pressures Calculated for each level of common rail pressure.
[Equation 3]

[0057]
The current learning value is calculated as an injection amount correction amount at the common rail pressure at the current pressure level, which is added to the injection amount command value (total Q / N) of the no-load fuel consumption / N of each injection. Here, the current learning value may be an injection period correction amount (injector energization pulse time correction amount) instead of the injection amount correction amount.
[0058]
Next, it is determined whether the calculation of the learning value at the common rail pressure of a plurality of different total pressure levels set in advance has been completed. For example, it is determined whether the calculation of the learning value at the common rail pressure of one pressure level E (MPa) has been completed (step S8). If the determination result is NO, that is, if the calculation of the learning value for each common rail pressure of a plurality of different total pressure levels (A, B, C, D) set in advance is not completed, the process proceeds to step S2. The process proceeds to step S2, and the next pressure level (for example, A → B, B → C, C → D) is simply changed from the previously set pressure level without changing the injection condition and the intake / exhaust condition of the engine 1 in step S2. , D → E), and from step S3, the pilot learning control is executed again, and from the ISC correction amount and the FCCB correction amount to each cylinder of the engine 1 at the common rail pressure of the next pressure level. Is calculated.
[0059]
If the determination result in step S8 is YES, that is, if it is confirmed that the calculation of the learning value for each common rail pressure of a plurality of different total pressure levels set in advance is completed, the calculation is performed in step S7. The learned values thus obtained, that is, the learned values for each cylinder of the engine 1 at the common rail pressure at each pressure level are written in a learning value map in the form of FIG. Each learning value for each cylinder is stored (backed up) in a memory such as a standby RAM or EEPROM (learning value storage means: step S9).
[0060]
Next, each learned value for each cylinder of the engine 1 at the stored common rail pressure at each pressure level is reflected as an injection amount correction amount when calculating the pilot injection amount based on the following equation (4) ( Step S10). Thereafter, the process exits the control routine of FIG.
(Equation 4)

[0061]
However, QPLB is an appropriate value (calculated from a characteristic map created by previously measuring the relationship between the engine speed (NE), the accelerator opening (ACCP), and the basic injection amount (Q) by experiments, etc.), and QISC is ISC. In the correction amount, KISC is the ISC correction amount reflection coefficient, QKTHF is the fuel temperature correction coefficient, QFCCB is the FCCB correction amount, KFCCB is the FCCB correction amount reflection coefficient, QKPC is the learning value pressure sensitivity correction coefficient, and QKNE is the learning value. QPLCPQ is an in-cylinder pressure correction coefficient, and QINT is an interval-dependent correction coefficient. The learning value is calculated from a learning value map in the format of FIG. 12 stored in the memory. The injection amount correction amount other than the pressure level used in the pilot learning control, that is, the injection amount correction amount other than the common rail pressure of a plurality of different total pressure levels set in advance is calculated by two-point interpolation or the like. Here, QPLCPQ and QINT may be injection amount correction amounts (injector energization pulse time correction amounts) instead of injection amount correction amounts.
[0062]
When the result of the determination in step S6 is YES, specifically, during the execution of the pilot learning control, the rotational speed fluctuation of each cylinder of the engine 1 is detected, and the rotational speed fluctuation between the cylinders exceeds a predetermined time. If the average rotation speed of the engine 1 is detected and the average rotation speed of the engine 1 does not substantially match the target rotation speed for a predetermined time or more, or if the average rotation speed of the engine 1 If the injection amount command value (each pilot injection amount), the injection timing (TFIN), the target fuel pressure (PFIN), the change amount of the FCCB correction amount, and the change amount of the ISC correction amount are outside the predetermined ranges, the engine 1 It is determined that the operation state is an unstable operation state, and each command value interval in the multi-stage injection at the time of executing the pilot learning control by the preset value (K). Decrease.
[0063]
For example, the command value interval (TPL1CR) which is the no-injection interval between QPL1 and QPL2 in the multi-stage injection at the time of executing the pilot learning control shown in FIGS. 9, 13 (a) and 14 (a) is represented by ｛TPL1CR ( i-1) Set to -K}. Also, a command value interval (TPL2CR), which is a no-injection interval between QPL2 and QPL3, is set to {TPL2CR (i-1) -K}. Also, a command value interval (TPL3CR), which is a no-injection interval between QPL3 and Qmain, is set to {TPL3CR (i-1) -K}. Also, the command value interval (TFUPCR), which is the no-injection interval between Qmain and Qfup, is set to {TFUPCR (i-1) -K} (no-injection interval changing means: step S11).
[0064]
Next, an interval minimum value guard determination is performed. Specifically, it is determined whether at least one command value interval (TPL1CR) of each command value interval in multi-stage injection at the time of execution of the pilot learning control is equal to or smaller than a minimum value (KMIN) (step S12). . If the result of this determination is NO, the process proceeds to step S3, where only the command value intervals are changed without changing other injection conditions, intake and exhaust conditions, etc. of the engine 1 in step S3. The learning control is executed again from S4 (re-learning control execution means).
[0065]
If the determination result in step S12 is YES, even if the command value intervals in the multi-stage injection at the time of execution of the pilot learning control are gradually reduced, the command value intervals at which the engine 1 can be operated in a stable operation state. Is determined to be impossible, that is, it is determined that the engine unstable state continues for a predetermined time or more even when the above-described pilot learning control is executed. The command value interval is set to the minimum value, and the pilot learning control is terminated (stopped, interrupted or prohibited) (learning control prohibiting means). This can prevent the unstable operation state of the engine 1 from continuing for a long time. At this time, the update and correction of the injection amount correction amount or the injection period correction amount for each cylinder are stopped, interrupted, or prohibited, so that the injection amount or injection period for each cylinder is erroneously learned (erroneously corrected) or excessively corrected. Correction can be prevented.
[0066]
[Features of the embodiment]
As in the present embodiment, the pilot injection amount correction value or pilot injection period correction amount, which is a learning value for each cylinder calculated using the ISC correction and the FCCB correction, is used to calculate the pilot injection amount command value (for example, TQ pulse In the pilot learning control for learning and correcting the variation of the actual pilot injection amount with respect to the time), the individual difference of the injector 4, and the deterioration amount of the injector 4 with time, when the pilot learning control is executed, the driving of the injector 4 of the specific cylinder is performed by the engine 1. By performing the fuel injection a plurality of times during the compression stroke and the expansion stroke, multi-injection in which the fuel injection is divided into a plurality of times is performed.
[0067]
However, due to variations in the injection start delay (TD) and the injection end delay (TDE) of the injector hardware, the actual injection interval becomes longer than the command value interval. As described above, when the actual injection interval becomes longer, the next pilot injection is performed at the time when the ignition by the pilot injection is almost extinguished, or the main injection is performed at the time when the fire by the pilot injection is almost extinguished, A misfire state in which fuel does not burn properly in the cylinder of the engine 1 may occur, and the operating state of the engine 1 may become unstable. Here, FIG. 13B is a diagram showing an example in which the injection end delay (TDE) is reduced, the actual interval is increased, and a misfire has occurred. FIG. 14B is a diagram illustrating an example in which the injection start delay (TD) increases, the actual interval increases, and a misfire occurs.
[0068]
Therefore, in the pilot learning control device of the present embodiment, the learning value is calculated by a method in which the sum of the above ISC correction amount and FCCB correction amount is proportionally divided by the total injection amount of the pilot injection amount and the main injection amount. If the operating state of the engine 1 is unstable during the execution of the pilot learning control, particularly if an increase in combustion noise or an increase in engine vibration is detected, each command value interval during execution of the pilot learning control is set to As shown in FIG. 13 (c) and FIG. 14 (c), the command is set such that the actual injection interval is gradually reduced so as to be the same as the target, and the engine 1 can be operated stably during execution of the pilot learning control. A value interval is searched for so that the pilot learning control can be continued without interrupting, suspending or prohibiting the pilot learning control as described above. . As shown in FIGS. 13C and 14C, the Q reduction of the actual pilot injection amount with respect to each injection amount command value is obtained by the pilot learning control using the above ISC correction and FCCB correction. to correct.
[0069]
This can prevent excessive correction due to erroneous learning or over-learning of the injection amount correction amount or injection period correction amount (injector energization pulse time correction amount) for each injection, so that combustion noise of the engine 1, engine vibration, and exhaust gas can be prevented. Deterioration of performance (exhaust emission) can be prevented. With this, even in the case where the pilot learning control is executed at a predetermined learning correction frequency, the pilot injection amount or the pilot injection period becomes as desired until the next calculation of the learning value. The engine performance can be sufficiently exhibited, and the engine performance such as combustion noise, engine vibration, and exhaust gas performance does not deteriorate.
[0070]
In addition, instead of the injection amount correction amount or injection period correction amount (injector energization pulse time correction amount) limited to the common rail pressure in the idling operation, the actual injection amount correction amount for the pilot injection period (injection amount command value) at a plurality of different common rail pressures. By calculating an injection amount correction amount or an injection period correction amount corresponding to the variation of the pilot injection amount, the individual difference of the injectors 4, and the aging deterioration amount of the injectors 4 for each cylinder, a wide operating range during normal engine operation can be obtained. Each learning value can be reflected over the range. As a result, the correlation between the ideal pilot injection period (injection amount command value) and the pilot injection amount can be obtained over the entire operation range of the engine 1.
[0071]
The common rail pressures other than the preset total pressure levels A, B, C, D, and E are subjected to two-point interpolation and the like, so that the actual vehicle including the common rail pressures other than the common rail pressure at the time of executing the pilot learning control is used. The learning value stored in the memory is reflected as an injection amount correction amount or an injection period correction amount in the calculation of the pilot injection amount (QPILOT) or the pilot injection period (injection amount command value: TQPILOT) over the entire use range of the common rail pressure. Can be. Thus, a correlation between the ideal pilot injection period (injection amount command value) and the pilot injection amount can be always obtained.
[0072]
[Modification]
In the present embodiment, an example in which the present invention is applied to a common rail type fuel injection system equipped with a pilot learning control device is shown. However, the present invention is not provided with a common rail and an electronic control type distribution type fuel injection pump or an electronic control type May be applied to an injection quantity control device for an internal combustion engine provided with the above-mentioned row type fuel injection pump or the like. Further, in this embodiment, an example in which the injector 4 formed of an electromagnetic fuel injection valve is used has been described, but an injector formed of a piezoelectric fuel injection valve may be used. The number of pilot injections (also referred to as pre-injections) performed prior to the main injection may be arbitrarily set to one or more, and the number of pilot injections (also referred to as after-injections) performed after the main injections May be arbitrarily set to zero or one or more times.
[0073]
In the present embodiment, the split injection shown in step S3 of the control routine of FIG. 7 is the equal split injection in which the injection is accurately and evenly divided into N times. It is not necessary to limit. Alternatively, N times equal split injection is performed, for example, totalQ = 5 mm ³ / Mm in case of / st ³ / St, 1mm ³ / St, 1mm ³ / St, 2mm ³ / St substantially equally divided into four injections, and the FCCB correction amount and the ISC correction amount are appropriately reflected in each injection according to the division method (for example, a proportional distribution of 1: 1: 1: 2 or 1/1/2). 4), the learning value may be calculated in step S7 of the control routine of FIG. Even when the present invention is implemented by the method as described above, substantially the same effects as in the above embodiment can be achieved.
[0074]
In this embodiment, the standby RAM or the EEPROM is used as the correction amount storing means for updating and storing the injection amount correction amount or the injection period correction amount for each cylinder of the engine 1, but the standby RAM or the EEPROM is not used. Using a non-volatile memory such as an EPROM or a flash memory, a DVD-ROM, a CD-ROM, or another storage medium such as a flexible disk, the previous learning value or the current learning value updated by the previous or current pilot learning control. The learning value may be stored. Also in this case, the stored contents are retained even after the ignition switch is turned off (IG-OFF) or after the engine key is removed from the key cylinder.
[0075]
Further, when the FCCB correction amount is equal to or more than a predetermined value by the above pilot learning control, when the ISC correction amount is equal to or more than a predetermined value, or when the total learning amount is equal to or more than a predetermined value, or when the previous learning value and the current learning value If the difference is out of the predetermined range, it is possible to detect that the injection amount varies more than the predetermined value with respect to the injection amount command value, and it is also possible to detect a failure of each individual injector. In this case, an abnormality warning lamp (indicator lamp) may be turned on to prompt the driver to replace the injector 4. Further, the above-described pilot learning control may be executed only for the target fuel pressure in the idling operation or the idling stable state. Further, the above-described pilot learning control may be performed at a constant or variable learning correction frequency (for example, traveling distance).
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an entire configuration of a common rail fuel injection system (Example).
FIG. 2 is a characteristic diagram for calculating a basic injection amount (Example).
FIG. 3 is a characteristic diagram for calculating an injection command pulse time (Example).
FIG. 4 is a timing chart showing an injector injection command pulse (TQ pulse), an injector drive current waveform, and a fuel injection rate (Example).
FIG. 5 is a characteristic diagram for calculating a pilot injection amount (Example).
FIG. 6 is a characteristic diagram for calculating a pilot interval (embodiment);
FIG. 7 is a flowchart showing a pilot learning control method (embodiment).
FIG. 8 is an explanatory diagram showing an injection pattern of equal split injection (Example).
FIG. 9 is a model diagram showing an outline of injection behavior and control contents (embodiment).
FIG. 10 is a model diagram showing an outline of injection behavior and control contents (embodiment).
FIG. 11 is a model diagram showing an outline of injection behavior and control contents (embodiment).
FIG. 12 is a diagram showing a learning value map (Example).
13 (a) is an operation explanatory diagram showing a target injection pattern, FIG. 13 (b) is an operation explanatory diagram showing an example in which an injection end delay is small and a misfire has occurred, and FIG. 13 (c) is an operation explanatory diagram. It is operation | movement explanatory drawing which showed the injection pattern after correction | amendment implementation (Example).
14A is an operation explanatory diagram showing a target injection pattern, FIG. 14B is an operation explanatory diagram showing an example in which an injection start delay is increased and a misfire occurs, and FIG. It is operation | movement explanatory drawing which showed the injection pattern after correction | amendment implementation (Example).
[Explanation of symbols]
1 engine (internal combustion engine)
2 common rail (accumulator)
3 Supply pump (fuel supply pump)
4 Injector (electromagnetic fuel injection valve)
10 ECU (no-injection interval determining means, learning control executing means, no-injection interval changing means, relearning control executing means, learning control inhibiting means)

Claims (7)

In accordance with a command injection amount or a command injection period that is set according to an operation state or an operation condition of the internal combustion engine, an injector driving unit that drives an injector mounted corresponding to each cylinder of the internal combustion engine is provided.
A fuel for an internal combustion engine that learns and corrects the variation of the actual injection amount with respect to the command injection amount or the command injection period and the aging deterioration amount of the injector from the injection amount correction amount or the injection period correction amount for each cylinder of the internal combustion engine. In the injection control device,
(A) A non-injection interval for setting each non-injection interval in a multi-stage injection in which fuel injection is divided into a plurality of times by performing the driving of the injector a plurality of times during a compression stroke and an expansion stroke of the internal combustion engine. Determining means;
(B) learning control execution means for executing learning control for updating the injection amount correction amount or the injection period correction amount for each cylinder of the internal combustion engine while performing the multi-stage injection;
(C) a non-injection interval for changing each non-injection interval in the multi-stage injection during the execution of the learning control, when the operation state of the internal combustion engine becomes unstable during the execution of the learning control; Change means;
(D) a re-learning control executing means for executing the learning control again while performing the multi-stage injection after changing each non-injection interval in the multi-stage injection at the time of executing the learning control by the non-injection interval changing means; And a fuel injection control device for an internal combustion engine. The fuel injection control device for an internal combustion engine according to claim 1,
Even if the non-injection interval in the multi-stage injection at the time of execution of the learning control is changed and the learning control is executed again, if the unstable operation state of the internal combustion engine continues for a predetermined time or more, the learning control is performed. A fuel injection control device for an internal combustion engine, comprising: a learning control prohibiting means for setting each non-injection interval in the multi-stage injection at the time of execution to a minimum value to suspend, suspend, or prohibit the learning control. The fuel injection control device for an internal combustion engine according to claim 1 or 2,
The learning control executing means detects a rotation speed variation of each cylinder of the internal combustion engine, compares the rotation speed variation with an average value of rotation speed variations of all cylinders, and smoothes the rotation speed variation between cylinders according to the comparison result. A fuel injection control device for an internal combustion engine, which updates and stores an injection amount correction amount or an injection period correction amount for each cylinder of the internal combustion engine. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 3,
The learning control executing means detects an average rotational speed of the internal combustion engine, compares the average rotational speed with a target rotational speed, and injects the fuel into each cylinder of the internal combustion engine so as to reach the target rotational speed according to the comparison result. A fuel injection control device for an internal combustion engine, wherein an amount correction amount or an injection period correction amount is updated and stored. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 4,
The non-injection interval changing means has an unstable state detecting means for detecting an unstable operating state of the internal combustion engine,
During the execution of the learning control, the unstable state detecting means detects when the combustion noise or vibration of the internal combustion engine is equal to or more than a predetermined value, or detects a rotation speed variation of each cylinder of the internal combustion engine, When the rotation speed fluctuation is not smoothed even after a predetermined time or more, or when the average rotation speed of the internal combustion engine is detected, and the average rotation speed of the internal combustion engine does not substantially match the target rotation speed for a predetermined time or more. A fuel injection control device for an internal combustion engine, which sometimes detects an unstable operation state of the internal combustion engine. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 4,
The non-injection interval changing means has an unstable state detecting means for detecting an unstable operating state of the internal combustion engine,
During the execution of the learning control, the unstable state detection means corrects each injection amount command value per one injection in the multi-stage injection, a command injection timing, a target fuel pressure, and an injection amount correction for each cylinder of the internal combustion engine. A fuel injection control device for an internal combustion engine, wherein an unstable operation state of the internal combustion engine is detected when the amount of change or the change amount of the injection period correction amount is outside a predetermined range. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 6,
The multi-stage injection is a multi-injection in which one or more pilot injections are performed before a main injection or a multi-injection in which one or more after injections are performed after a main injection. Injection control device.

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