JP3889379B2 - Apparatus for controlling an internal combustion engine having a plurality of cylinder groups using the concentration of evaporated fuel - Google Patents

Description

【００４０】
パージ補正係数ＫＡＦＥＶＡＣＴはベーパ濃度係数ＫＡＦＥＶに基づいて算出されるので、適切な燃料噴射量を算出するためには、ベーパ濃度係数ＫＡＦＥＶを良好な精度で推定する必要がある。図３を参照して、本発明の理解を助けるために、ベーパ濃度係数ＫＡＦＥＶを算出する方法の概略を説明する。
【００４１】
図３には、目標空燃比係数ＫＣＭＤに対する実空燃比係数ＫＡＣＴの遷移、パージ無し空燃比学習値（以下、パージ無し学習値と呼ぶ）ＫＲＥＦＸに対する空燃比補正係数ＫＡＦの遷移、および算出されたベーパ濃度係数ＫＡＦＥＶの遷移の例を示す。ここで、パージ無し学習値ＫＲＥＦＸは、パージカットを実施している間の空燃比係数ＫＡＦをなまし平均した値である。図３に示されるように、パージ無し学習値ＫＲＥＦＸを基準として、高側判定値「ＫＲＥＦＸ＋ＤＫＡＦＥＶＸＨ」および低側判定値「ＫＲＥＦＸ−ＤＫＡＦＥＶＸＬ」が設定される。
【００４２】
時間ｔ２において、実空燃比係数ＫＡＣＴが目標空燃比係数ＫＣＭＤを超えた後、時間ｔ３〜ｔ４において空燃比補正係数ＫＡＦが低側判定値「ＫＲＥＦＸ−ＤＫＡＦＥＶＸＬ」を下回ると、蒸発燃料による影響で、空燃比が目標空燃比に対してリッチ状態になったと判定される。その結果、時間ｔ３〜ｔ４において、ベーパ濃度係数ＫＡＦＥＶは、増加するよう算出される。
【００４３】
時間ｔ５において、実空燃比係数ＫＡＣＴが目標空燃比係数ＫＣＭＤを下回った後、時間ｔ６〜ｔ７において、空燃比補正係数ＫＡＦが高側判定値「ＫＲＥＦＸ＋ＤＫＡＦＥＶＸＨ」を超えると、蒸発燃料による影響で、空燃比が目標空燃比に対してリーン状態になったと判断される。その結果、時間ｔ６〜ｔ７において、ベーパ濃度係数ＫＡＦＥＶは、減少するよう算出される。
【００４４】
時間ｔ１〜ｔ３、時間ｔ４〜ｔ６および時間ｔ７〜ｔ９において、空燃比補正係数ＫＡＦは、高側判定値「ＫＲＥＦＸ＋ＤＫＡＦＥＶＸＨ」と低側判定値「ＫＲＥＦＸ−ＤＫＡＦＥＶＸＬ」との間にある。空燃比補正係数ＫＡＦがこの領域にあるということは、蒸発燃料の影響によって空燃比がリッチおよびリーンのいずれにも傾く可能性があることを示す。空燃比補正係数ＫＡＦがこの領域にあるとき、ベーパ濃度係数ＫＡＦＥＶは、パージ無し学習値ＫＲＥＦＸと、パージ有り空燃比学習値（以下、パージ有り学習値と呼ぶ）ＫＲＥＦとの差に応じて補正される。ここで、パージ有り学習値ＫＲＥＦは、パージが実行されている間に空燃比補正係数ＫＡＦをなまし平均した値である。
【００４５】
このように、ベーパ濃度係数ＫＡＦＥＶは推定により算出されるので、運転状態によっては誤差を含むことがある。この誤差は、パージ有り学習値ＫＲＥＦとパージ無し学習値ＫＲＥＦＸの差によって表される。なぜならば、ベーパ濃度係数ＫＡＦＥＶが正しければ、パージ有り学習値ＫＲＥＦとパージ無し学習値ＫＲＥＦＸは同じ値を示すからである。
【００４６】
図４は、この発明に従う制御装置の機能ブロック図である。各機能ブロックで表される機能は、典型的にはコンピュータプログラムによって実行される。代替的には、各機能ブロックで表される機能を実行するよう構成された任意のハードウェアによって、各機能ブロックを実現してもよい。
【００４７】
各機能ブロックは、それぞれのバンクについて、所定の機能を実現する。以下の算出式は、特に記載されない限り、バンク１およびバンク２のそれぞれについて実行される。
【００４８】
吸入空気量算出部５１は、式（４）に基づいて、吸入空気量ＱＡＩＲを算出する。
【００４９】
【数４】
ＱＡＩＲ＝ＴＩＭ×ＮＥ×２×ＫＱＡＩＲ×ＫＰＡ （４）
【００５０】
前述したように、ＴＩＭは基本燃料噴射量を示す。ＫＱＡＩＲは、燃料噴射量を空気の流量に換算するための係数であり、固定値（たとえば、０．４５L/ms）を持つ。ＫＰＡは、吸気管圧力ＰＢに応じた流量の変動を補正するための係数である。
【００５１】
吸入空気量算出部５１は、さらに、吸入空気量ＱＡＩＲに対する蒸発燃料の割合、すなわち基本パージ量ＱＰＧＣＢＡＳＥを、式（５）に基づいて算出する。
【００５２】
【数５】
ＱＰＧＣＢＡＳＥ＝ＱＡＩＲ×ＫＱＰＧＢ （５）
【００５３】
ここで、ＫＱＰＧＢは目標パージ率を示しており、たとえば０．０４である。この場合、吸入空気量ＱＡＩＲの４％に蒸発燃料を含めることになる。
【００５４】
次に、パージ流量算出部５２は、基本パージ量ＱＰＧＣＢＡＳＥに基づいて、目標パージ流量ＱＰＧＣＭＤを式（６）に基づいて算出する。目標パージ流量ＱＰＧＣＭＤは、今回のサイクルにおいてエンジンの吸気系にパージするパージ流量の目標値を表す。
【００５５】
【数６】
ＱＰＧＣＭＤ＝ＱＰＧＣＢＡＳＥ×ＫＰＧＴ （６）
【００５６】
ＫＰＧＴはパージ流量係数であり、１以下の値を持つ。この係数ＫＰＧＴを制御することにより、目標パージ流量ＱＰＧＣＭＤの量を制御することができる。
【００５７】
一実施例では、係数ＫＰＧＴは、サイクルごとに所定量だけ増やされる。この増加処理を実行するタイミングは、ベーパ濃度ＫＡＦＥＶおよび吸入空気量ＱＡＩＲに基づいて決定される。ベーパ濃度係数ＫＡＦＥＶが大きいほど、また吸入空気量ＱＡＩＲが小さいほど、該増加処理が実施される時間間隔が長く設定され、目標パージ流量ＱＰＧＣＭＤがより緩やかに増えるようにする。
【００５８】
係数ＫＰＧＴの増加処理は、たとえば、パージ流量が寄与する燃料量が、所定の上限値を超えない限り実施される。これにより、空燃比フィードバック制御に影響を及ぼさないように、なるべく多くの量の蒸発燃料をエンジンに供給することができる。
【００５９】
さらに、パージ流量算出部５２は、吸入空気量ＱＡＩＲに基づいて、今回のサイクルでパージするパージ流量ＱＰＧＣを、式（７）に基づいて算出する。
【００６０】
【数７】
ＱＰＧＣ(ｋ)＝ＱＰＧＣ(ｋ−１)＋（ＱＡＩＲ×ＫＤＱＰＧＣ） （７）
【００６１】
ここで、ｋはサイクルを識別する数字であり、（ｋ）は今回のサイクルを示し、（ｋ−１）は前回のサイクルを示す。ＫＤＱＰＧＣは予め決められた固定値（たとえば、０．００３）である。式（７）に示されるように、パージ流量ＱＰＧＣは、徐々に目標パージ流量ＱＰＧＣＭＤに達するよう制御される。
【００６２】
デューティ算出部５３は、パージ流量算出部５２から受け取ったパージ流量ＱＰＧＣがパージされるように、パージ制御弁を駆動するデューティ比ＰＧＣＭＤを、式（８）に基づいて算出する。デューティ比は、パージ制御弁が開弁している比率を表す。
【００６３】
【数８】

【００６４】
ＫＤＵＴＹは、パージ流量をデューティ比に換算するための係数であり、固定値（たとえば、３．８%・min/L）を持つ。ＫＤＰＢＧは、差圧に応じてパージ制御弁の開度が変化するので、それを補正するための係数である。ＰＧＣＭＤ０は、パージ流量ＱＰＧＣに対応するデューティ比を表しており、目標デューティ比と呼ばれる。バッテリ電圧ＶＢおよび吸気管圧力ＰＢに依存して、パージ制御弁が開き始めるまでに何らかの遅れが生ずる。ＤＰＧＣＶＢＸおよびＤＰＧＣ０は、それぞれ、この遅れ（以下、無効時間と呼ぶ）を補正する係数である。
【００６５】
デューティ算出部５３は、デューティ比ＰＧＣＭＤに対して、所定の上限値および下限値でリミット処理を行い、最終デューティ比ＤＯＵＴＰＧＣを出力する。こうして、パージ制御弁の開度は、最終デューティ比ＤＯＵＴＰＧＣに従って制御される。
【００６６】
空燃比制御部５４は、空燃比を目標空燃比に収束させるように、ＬＡＦセンサ（バンク１についてＬＡＦセンサ１３ａであり、バンク２についてはＬＡＦセンサ１３ｂ）からの出力に基づいて空燃比係数ＫＡＦを算出するフィードバック制御を、バンクごとに実施する。
【００６７】
空燃比学習値算出部５５は、空燃比制御部５４によって算出された空燃比係数ＫＡＦに基づいて、パージ有り学習値ＫＲＥＦと、パージ無し学習値ＫＲＥＦＸとを、式（９）に基づいて算出する。
【００６８】
【数９】

【００６９】
＃ＣＲＥＦおよび＃ＣＲＥＦＸは、それぞれ、重み付け係数を表す所定値である。この値により、前回のサイクルで算出されたＫＲＥＦ(k-1)およびＫＲＥＦＸ(k-1)に対して、どれだけ空燃比補正係数ＫＡＦを反映させるかを決定する。
【００７０】
気筒休止制御部５６は、油圧コントロールバルブ４１および４２（図２）に制御信号を送って、気筒休止機構２３に、バンク１に含まれる＃１〜＃３の気筒を休止させる。気筒休止制御部５６は、気筒休止運転を開始するとき、フラグＦ＿ＣＳＴＰの値を１にセットする。
【００７１】
ベーパ濃度係数算出部５７は、空燃比制御部５４によって算出された空燃比補正係数ＫＡＦ、空燃比学習値算出部５５によって算出された学習値ＫＲＥＦＸおよびＫＲＥＦに基づいて、ベーパ濃度係数ＫＡＦＥＶを推定する。
【００７２】
ベーパ濃度係数算出部５７は、さらに、気筒休止制御部５６によって設定された気筒休止フラグＦ＿ＣＳＴＰを調べる。フラグＦ＿ＣＳＴＰの値が１の時は、バンク１に含まれる気筒が休止していることを示す。ベーパ濃度係数算出部５７は、フラグＦ＿ＣＳＴＰの値が１の時は、バンク１のベーパ濃度係数に、バンク２（すなわち、運転している気筒群）について推定されたベーパ濃度係数ＫＡＦＥＶを代入する。こうして、バンク１が運転を再開した時には、該代入されたベーパ濃度係数ＫＡＦＥＶを用いて、バンク１の燃料噴射量が算出される。
【００７３】
輸送遅れ算出部５８は、エンジン回転数ＮＥに基づいて、パージ輸送遅れＣＰＧＤＬＹＲＸを算出する。パージ輸送遅れＣＰＧＤＬＹＲＸは、蒸発燃料がパージ通路にパージされてからエンジンの吸気系に送られるまでの時間的な遅れを示す。パージ輸送遅れＣＰＧＤＬＹＲＸは整数ｎで表され、ｎが大きくなるにつれ輸送遅れが大きいことを示す。代替的に、パージ輸送遅れを、エンジン回転数ＮＥの代わりに吸入空気量ＱＡＩＲに基づいて算出するようにしてもよい。
【００７４】
目標パージ補正係数算出部５９は、式（１０）に基づいて、目標パージ補正係数ＫＡＦＥＶＡＣＺを算出する。
【００７５】
【数１０】

【００７６】
ＰＧＲＡＴＥおよびＱＲＡＴＥは、式（１１）および（１２）で表される。
【００７７】
【数１１】

【００７８】
「ＰＧＲＡＴＥ×ＱＲＡＴＥ」は、今回のサイクルにおいてエンジンの吸気系にパージするパージ流量の、要求燃料（式（１）で表される）に含めることのできるパージ流量に対する割合を示す。燃料はベーパ濃度係数ＫＡＦＥＶに依存して表されるので、式（１０）に示されるように、「ＰＧＲＡＴＥ×ＱＲＡＴＥ」にベーパ濃度係数ＫＡＦＥＶを乗算することにより、目標パージ補正係数ＫＡＦＥＶＡＣＺを算出することができる。
【００７９】
目標パージ補正係数算出部５９は、０〜（ｎ−１）の番号がそれぞれ付与された複数のバッファを有しており、今回のサイクルで算出された目標パージ補正係数をゼロ番目のバッファに格納し、前回のサイクルで算出された目標パージ補正係数を１番目のバッファに格納し、．．．というように、目標パージ補正係数を時系列に格納する。
【００８０】
目標パージ補正係数算出部５９は、輸送遅れ算出部５８から蒸発燃料の輸送遅れＣＰＧＤＬＹＲＸの値ｎを受け取り、該ｎに対応する番号のバッファから、目標パージ補正係数ＫＡＦＥＶＡＣＺを抽出する。たとえば、受け取ったＣＰＧＤＬＹＲＸの値ｎが３ならば、３番目のバッファから目標パージ補正係数ＫＡＦＥＶＡＣＺを抽出する。
【００８１】
パージ補正係数算出部６０は、パージ補正係数ＫＡＦＥＶＡＣＴを、式（１３）に基づいて算出する。
【００８２】
【数１２】
ＫＡＦＥＶＡＣＴ＝ＫＡＦＥＶＡＣＺ×ＫＫＥＶＧ （１３）
【００８３】
ＫＫＥＶＧは高濃度補正係数を示しており、蒸発燃料の濃度が非常に高い時の空燃比への影響を補正するための係数である。高濃度補正係数ＫＫＥＶＧは、蒸発燃料の濃度の高さに応じて、１より大きい値が設定される。
【００８４】
前述したように、パージ補正係数ＫＡＦＥＶＡＣＴは、要求燃料に対してパージ流量ＱＰＧＣが寄与する燃料量の割合を示す。パージ流量ＱＰＧＣが寄与する燃料量の割合は、まず目標パージ補正係数ＫＡＦＥＶＡＣＺとして算出され、これに高濃度補正係数ＫＫＥＶＧを乗算して補正したものを、最終的にパージ補正係数ＫＡＦＥＶＡＣＴに設定する。
【００８５】
燃料噴射量算出部６１は、パージ補正係数算出部６０からパージ補正係数ＫＡＦＥＶＡＣＴを受け取り、上記の式（３）に従って、燃料噴射量ＴＣＹＬを算出する。それぞれのバンクについて算出された燃料噴射量ＴＣＹＬは、燃料噴射弁を介して該バンクに供給される。こうして、パージ流量ＱＰＧＣが寄与する蒸発燃料量（すなわち、パージ補正量）を差し引いた量の燃料が、燃料噴射弁を介してエンジンに供給される。
【００８６】
図５は、バンク１について、ベーパ濃度係数ＫＡＦＥＶを算出する条件を決定するフローチャートである。実空燃比係数ＫＡＦは、バンク１用のＬＡＦセンサ１３ａの検出値に基づく値である。このフローチャートは、一定の時間間隔で繰り返し実行される。
【００８７】
ステップＳ１０１およびＳ１０２において、ＤＫＡＦＥＶＸＨ／ＤＫＡＦＥＶＸＬテーブルをアクセスし、吸入空気量ＱＡＩＲに基づいて高側判定値ＤＫＡＦＥＶＸＨおよび低側判定値ＤＫＡＦＥＶＸＬ（図２を参照）をそれぞれ求める。図８は、このテーブルの一例を示す。高側および低側判定値ＤＫＡＦＥＶＸＨおよびＤＫＡＦＥＶＸＬは、吸入空気量ＱＡＩＲが大きくなるほど小さくなるよう設定される。
【００８８】
ステップＳ１０３において、空燃比学習値ＫＲＥＦＸから低側判定値ＤＫＡＦＥＶＸＬを減算することによって得られる値が空燃比補正係数ＫＡＦより大きく、かつステップＳ１０４において、実空燃比係数ＫＡＣＴが目標空燃比係数ＫＣＭＤより大きければ、蒸発燃料の影響で空燃比が目標空燃比に対してリッチ状態にあることを示す。このような状態の場合には、フラグＦ＿ＫＡＦＥＶＰに値１をセットする（Ｓ１０５）。値１がセットされたフラグＦ＿ＫＡＦＥＶＰは、ベーパ濃度係数ＫＡＦＥＶを増やすべき状態を示す。
【００８９】
空燃比学習値ＫＲＥＦＸに高側判定値ＤＫＡＦＥＶＸＨを加算することによって得られる値が空燃比補正係数ＫＡＦより小さく（Ｓ１０７）、かつ実空燃比係数ＫＡＣＴが目標空燃比係数ＫＣＭＤより小さければ（Ｓ１０８）、蒸発燃料の影響で空燃比が目標空燃比に対してリーン状態にあることを示す。このような状態の場合には、フラグＦ＿ＫＡＦＥＶＭに値１をセットする（Ｓ１０９）。値１がセットされたフラグＦ＿ＫＡＦＥＶＭは、ベーパ濃度係数ＫＡＦＥＶを減らすべき状態を示す。
【００９０】
ステップＳ１０３およびＳ１０７の両方の判断ステップがＮｏであるとき、空燃比補正係数ＫＡＦが、高側判定値ＤＫＡＦＥＶＸＨと低側判定値ＤＫＡＦＥＶＸＬの間にあることを示す（図２を参照）。パージ有り学習値ＫＲＥＦがパージ無し学習値ＫＲＥＦＸより小さければステップＳ１１１に進み、学習値ＫＲＥＦが学習値ＫＲＥＦＸ以上ならばステップＳ１１５に進む。
【００９１】
ステップＳ１１１において空燃比補正係数ＫＡＦが学習値ＫＲＥＦＸより小さく、かつステップＳ１１２において実空燃比ＫＡＣＴが目標空燃比ＫＣＭＤより大きければ、パージの影響で空燃比がリッチ側に傾いていることを示す。この場合には、フラグＦ＿ＫＡＦＥＶＣに値１をセットする。値１がセットされたフラグＦ＿ＫＡＦＥＶＣは、ベーパ濃度係数ＫＡＦＥＶを、学習値ＫＲＥＦおよびＫＲＥＦＸの差に応じて補正すべき状態を示す（Ｓ１１３）。
【００９２】
一方、ステップＳ１１５において空燃比補正係数ＫＡＦが学習値ＫＲＥＦＸより大きく、かつステップＳ１１６において実空燃比ＫＡＣＴが目標空燃比ＫＣＭＤより小さければ、空燃比がリーン側に傾いていることを示す。この場合も、フラグＦ＿ＫＡＦＥＶＣに値１をセットする（Ｓ１１７）。
【００９３】
その他の状態では、すべてのフラグがゼロにセットされ（Ｓ１０６およびＳ１１４）、ベーパ濃度係数ＫＡＦＥＶは更新されない。
【００９４】
バンク２についても、図５に示されるフローチャートと同様の処理が実施される。この場合、実空燃比係数、パージ無し学習値、およびパージ有り学習値は、バンク２用のＬＡＦセンサ１３ｂの検出値に基づいて算出された値が用いられる。バンク２については、フラグＦ＿ＫＡＦＥＶＰ、Ｆ＿ＫＡＦＥＶＭおよびＦ＿ＫＡＦＥＶＣの代わりに、フラグＦ＿ＫＡＦＥＶＢ２Ｐ、Ｆ＿ＫＡＦＥＶＢ２ＭおよびフラグＦ＿ＫＡＦＥＶＢ２Ｃがセットされる。
【００９５】
図６は、ベーパ濃度係数ＫＡＦＥＶを算出するフローチャートである。このフローチャートは、一定の時間間隔で繰り返し実行される。このフローチャートにおいて、ＫＡＦＥＶは、バンク１についてのベーパ濃度係数を表し、ＫＡＦＥＶＢ２は、バンク２についてのベーパ濃度係数を表す。ＫＲＥＦＸおよびＫＲＥＦは、バンク１用に設けられたＬＡＦセンサ１３ａの検出値に基づいて算出されたパージ無し学習値およびパージ有り学習値をそれぞれ示し、ＫＲＥＦＸＢ２およびＫＲＥＦＢ２は、バンク２用に設けられたＬＡＦセンサ１３ｂの検出値に基づいて算出されたパージ無し学習値およびパージ有り学習値をそれぞれ示す。
【００９６】
ステップＳ２０１において、現在空燃比フィードバック制御が実行されているかどうか判断する。フィードバック制御中でなければこのルーチンを抜け、フィードバック制御中ならばステップＳ２０２に進む。ステップＳ２０２において、パージ流量ＱＰＧＣがゼロならば、今回のサイクルでは蒸発燃料をパージしないことを示すので、このルーチンを抜ける。パージ流量ＱＰＧＣがゼロでなければ、ステップＳ２０３に進む。
【００９７】
ステップＳ２０３において、バンク２のフラグＦ＿ＫＡＦＥＶＢ２Ｐの値を調べる。前述のステップＳ１０５を参照して述べたように、フラグＦ＿ＫＡＦＥＶＢ２Ｐの値が１ならば、空燃比がリッチ状態にあることを示す。ステップＳ２０４に進み、バンク２のベーパ濃度係数ＫＡＦＥＶＢ２を、所定値ＤＫＥＶＡＰＯＰ（たとえば、０．０５）だけ増やす。
【００９８】
ステップＳ２０５において、バンク２のフラグＦ＿ＫＡＦＥＶＢ２Ｍの値を調べる。前述のステップＳ１０９を参照して述べたように、フラグＦ＿ＫＡＦＥＶＢ２Ｍの値が１ならば、空燃比がリーン状態にあることを示す。ステップＳ２０６に進み、バンク２のベーパ濃度係数ＫＡＦＥＶＢ２を、所定値ＤＫＥＶＡＰＯＭ（たとえば、０．０８）だけ減らす。
【００９９】
ステップＳ２０７において、バンク２のフラグＦ＿ＫＡＦＥＶＢ２Ｃの値を調べる。前述のステップＳ１１３およびＳ１１７を参照して述べたように、フラグＦ＿ＫＡＦＥＶＢ２Ｃの値が１ならば、空燃比がリッチまたはリーン状態に傾いていることを示す。ステップＳ２０８に進み、学習値ＫＲＥＦＢ２およびＫＲＥＦＸＢ２の差に応じて、ベーパ濃度係数ＫＡＦＥＶＢ２を算出する。すなわち、パージ無し学習値ＫＲＥＦＸＢ２からパージ有りＫＲＥＦＢ２を引いた値に所定値ＣＡＦＥＶ（たとえば、０．０２）を乗算した値を加算することにより、ベーパ濃度係数ＫＡＦＥＶＢ２を更新する。
【０１００】
バンク２について、図５のステップＳ１１３の場合はＫＲＥＦＢ２＜ＫＲＥＦＸＢ２なので、ステップＳ２０８の更新処理によりベーパ濃度係数ＫＡＦＥＶＢ２は大きくなる。図５のステップＳ１１７の場合はＫＲＥＦＢ２＞ＫＲＥＦＸＢ２なので、ステップＳ２０８の更新処理によりベーパ濃度係数ＫＡＦＥＶＢ２は小さくなる。ステップＳ２０７の判断がＮｏの時は、ベーパ濃度係数ＫＡＦＥＶＢ２は更新されない。
【０１０１】
ステップＳ２０９において、気筒休止フラグＦ＿ＣＳＴＰの値を調べる。Ｆ＿ＣＳＴＰの値が１ならば、バンク１に含まれる気筒が休止していることを示す。ステップＳ２１０に進み、バンク１についてのベーパ濃度係数ＫＡＦＥＶに、バンク２について算出されたベーパ濃度係数ＫＡＦＥＶＢ２をセットする。
【０１０２】
ステップＳ２１１において、バンク１のフラグＦ＿ＫＡＦＥＶＰの値を調べる。ステップＳ２０３と同様に、フラグＦ＿ＫＡＦＥＶＰの値が１ならば、バンク１のベーパ濃度係数ＫＡＦＥＶを、所定値ＤＫＥＶＡＰＯＰ（たとえば、０．０５）だけ増やす（Ｓ２１２）。
【０１０３】
ステップＳ２１３において、バンク１のフラグＦ＿ＫＡＦＥＶＭの値を調べる。ステップＳ２０５と同様に、フラグＦ＿ＫＡＦＥＶＭの値が１ならば、バンク１のベーパ濃度係数ＫＡＦＥＶを、所定値ＤＫＥＶＡＰＯＭ（たとえば、０．０８）だけ減らす（Ｓ２１４）。
【０１０４】
ステップＳ２１５において、バンク１のフラグＦ＿ＫＡＦＥＶＣの値を調べる。ステップＳ２０７と同様に、フラグＦ＿ＫＡＦＥＶＣの値が１ならば、学習値ＫＲＥＦＸからＫＲＥＦを引いた値に所定値ＣＡＦＥＶ（たとえば、０．０２）を乗算した値を加算することにより、ベーパ濃度係数ＫＡＦＥＶを更新する（Ｓ２１６）。ステップＳ２１５の判断がＮｏならば、ベーパ濃度係数ＫＡＦＥＶは更新されない。
【０１０５】
こうして、ステップＳ２１０に示されるように、バンク１の気筒群の運転が停止している時には、バンク１の気筒群には、運転しているバンク２の気筒群について算出されたベーパ濃度が設定される。バンク１の気筒群の運転が再開した時、このように設定されたベーパ濃度が、バンク１の気筒群についてのパージ補正量および燃料噴射量の算出に用いられる。すべての気筒について適切なベーパ濃度が設定された状態で全気筒運転が再開されるので、全気筒運転の再開時に、気筒間で空燃比のずれが生じることを回避することができる。
【０１０６】
図７は、推定されたベーパ濃度係数ＫＡＦＥＶを用いて、燃料噴射量を補正するためのパージ補正係数ＫＡＦＥＶＡＣＴをバンク１について算出するフローチャートである。このフローチャートは、一定の時間間隔で繰り返し実行される。
【０１０７】
ステップＳ３０１において、パージ流量レートＱＲＡＴＥを求める。これは、前述した式（１２）に従って算出される。
【０１０８】
ステップＳ３０２において、パージ輸送遅れテーブルＣＰＧＤＬＹＲＸをアクセスし、エンジン回転数ＮＥに基づいてパージ輸送遅れＣＰＧＤＬＹＲＸを求める。前述したように、パージ輸送遅れＣＰＧＤＬＹＲＸは、蒸発燃料がパージ制御弁を介してパージ通路にパージされてから、エンジンの吸気系に到達するまでの時間的遅れを示す。この実施例では、パージ輸送遅れＣＰＧＤＬＹＲＸは整数ｎで表される。図９に、パージ輸送遅れテーブルＣＰＧＤＬＹＲＸテーブルの例を示す。パージ輸送遅れテーブルＣＰＧＤＬＹＲＸテーブルは、回転ＮＥが大きくなるほど、パージ輸送遅れＣＰＧＤＬＹＲＸも大きくなるように設定されている。これは、エンジン回転数ＮＥが大きいほど、蒸発燃料がパージされてからエンジンの吸気系に到達するまでの間に実行される吸入工程数が増加するからである。
【０１０９】
ステップＳ３０３において、リングバッファを１つだけシフトする。リングバッファは、たとえばＫＡＦＥＶＲＴ０〜ＫＡＦＥＶＲＴｆの１６個のバッファから構成される。リングバッファをシフトするということは、ＫＡＦＥＶＲＴ０〜ＫＡＦＥＶＲＴｅに格納されたデータを、ＫＡＦＥＶＲＴ１〜ＫＡＦＥＶＲＴｆにそれぞれシフトすることを示す。ＫＡＦＥＶＲＴｆに格納されていたデータは廃棄される。こうして、ＫＡＦＥＶＲＴ０を空にする。
【０１１０】
ステップＳ３０４において、パージ流量レートＱＲＡＴＥに、式（１１）に従って算出されたデューティレートＰＧＲＡＴＥを乗算したものを、バッファＫＡＦＥＶＲＴ０に格納する。こうして、ゼロ番目のバッファには、今回のサイクルで算出された「ＰＧＲＡＴＥ×ＱＲＡＴＥ」が格納される。１番目、２番目、．．．のバッファ（すなわち、ＫＡＦＥＶＲＴ１、ＫＡＦＥＶＲＴ２、、、）には、それぞれ、前回、前々回、．．．のサイクルで算出された「ＰＧＲＡＴＥ×ＱＲＡＴＥ」が格納されている。
【０１１１】
ステップＳ３０５に進み、前述の式（１０）に従い、目標パージ補正係数ＫＡＦＥＶＡＣＺを求める。具体的には、ベーパ濃度係数ＫＡＦＥＶに、ステップ３０２で求めたパージ輸送遅れの値ｎに対応するＫＡＦＥＶＲＴｎを乗算し、目標パージ補正係数ＫＡＦＥＶＡＣＺを算出する。たとえば、パージ輸送遅れＣＰＧＤＬＹＲＸが「４」ならば、バッファＫＡＦＥＶＲＴ４に格納されたＫＡＦＥＶＲＴの値が使用される。
【０１１２】
ステップＳ３０６〜Ｓ３０９は、高濃度補正係数ＫＫＥＶＧを算出する処理を示す。ステップＳ３０６において、ベーパ濃度係数ＫＡＦＥＶと、ガード係数ＫＥＶＡＣＴＧを比較する。ガード係数ＫＥＶＡＣＴＧは、運転状態に応じて算出される係数である。ベーパ濃度係数ＫＡＦＥＶがガード係数ＫＥＶＡＣＴＧより大きければ、蒸発燃料の濃度が非常に高いことを示す。ステップＳ３０７において、「ＫＡＦＥＶ／ＫＥＶＡＣＴＧ」を計算し、高濃度係数ＫＫＥＶＧを求める。
【０１１３】
一方、ベーパ濃度係数ＫＡＦＥＶがガード係数ＫＥＶＡＣＴＧより小さければ、蒸発燃料の濃度が補正するほどには大きくないことを示す。ステップＳ３０８において、高濃度補正係数ＫＫＥＶＧに１をセットする。
【０１１４】
ステップＳ３０９に進み、式（１３）に示されるように、目標パージ補正係数ＫＡＦＥＶＡＣＺに、ステップＳ３０７またはＳ３０８で求めた高濃度係数ＫＫＥＶＧを乗算し、パージ補正係数ＫＡＦＥＶＡＣＴを求める。
【０１１５】
バンク２についても、図７と同様の処理が実施される。バンク２のベーパ濃度係数ＫＡＦＥＶＢ２を用いて、バンク２のパージ補正係数が算出される。
【０１１６】
以上のように、この発明によれば、ベーパ濃度は、気筒休止運転を考慮して算出される。このように算出されたベーパ濃度に基づいて燃料噴射量が算出されるので、気筒休止制御が実施される場合でも、気筒群間に空燃比のずれが生じるのを回避することができる。
【０１１７】
このように算出されたベーパ濃度は、当然ながら、図４を参照して説明したパージ流量ＱＰＧＣの計算にも用いられることができる。さらに、このようにして算出されたベーパ濃度を、複数の気筒群を備えるエンジンのための他のエンジン制御に用いることができる。
【０１１８】
上記実施例では、ＬＡＦセンサを用いた例を示したが、Ｏ２センサを用いた場合にも本発明を適用することができる。Ｏ２センサの検出値に基づいて、空燃比フィードバック制御を、気筒群ごとに実施することができる。
【０１１９】
本発明は、クランク軸を鉛直方向とした船外機などのような船舶推進機用エンジンにも適用が可能である。
【０１２０】
【発明の効果】
この発明によれば、複数の気筒を備えるエンジンにおいて気筒休止運転が実施された場合でも、それぞれの気筒群について適切なベーパ濃度が設定された状態で、エンジンを制御することができる。
【図面の簡単な説明】
【図１】この発明の一実施例に従う、内燃機関および制御装置を概略的に示す図。
【図２】この発明の一実施例に従う、気筒休止機構を駆動するための回路を示す図。
【図３】この発明の一実施例に従う、実空燃比係数、空燃比補正係数、およびベーパ濃度の時間的遷移の一例を示す図。
【図４】この発明の一実施例に従う、制御装置の機能ブロック図。
【図５】この発明の一実施例に従う、ベーパ濃度係数ＫＡＦＥＶの算出条件を決定するフローチャート。
【図６】この発明の一実施例に従う、ベーパ濃度係数ＫＡＦＥＶを算出するフローチャート。
【図７】この発明の一実施例に従う、パージ補正係数ＫＡＦＥＶＡＣＴを算出するフローチャート。
【図８】この発明の一実施例に従う、高側および低側判定値ＤＫＡＦＥＶＸＨおよびＤＫＡＦＥＶＸＬを求めるためのテーブルを示す図。
【図９】この発明の一実施例に従う、パージ輸送遅れを求めるためのＣＰＧＤＬＹＲＸテーブルを示す図。
【符号の説明】
１ エンジン
５ ＥＣＵ
２３ 気筒休止機構[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for controlling an engine having a plurality of cylinder groups using the concentration of evaporated fuel.
[0002]
[Prior art]
The fuel evaporated from the fuel tank is supplied to the intake passage and burned in the engine. This supply of the evaporated fuel to the intake passage may cause fluctuations in the air-fuel ratio. In order to avoid such fluctuations, the concentration of the evaporated fuel is learned, and the fuel supply amount supplied to the engine via the fuel injection valve and / or the evaporated fuel is supplied to the intake passage via the purge control valve with the learned value. The purge flow rate for purging is corrected.
[0003]
On the other hand, when the engine includes a plurality of cylinder groups, air-fuel ratio feedback control is executed for each of the plurality of cylinder groups. In such air-fuel ratio feedback control, a technique for preventing a decrease in accuracy of learning the concentration of evaporated fuel is known. According to this method, when it is detected that the concentration of evaporated fuel is high in a certain cylinder group, learning of the concentration of evaporated fuel is prohibited for all cylinder groups (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
JP 2000-230449 A
[0005]
[Problems to be solved by the invention]
In the conventional method of learning the concentration of the evaporated fuel in an engine having a plurality of cylinder groups, the cylinder group pause is not considered. In cylinder deactivation control, a certain cylinder group (for example, bank 1) is deactivated and another cylinder group (for example, bank 2) is operated. The concentration of the evaporated fuel is calculated based on the oxygen concentration detected by an oxygen concentration sensor provided in the exhaust passage of the engine. When the bank 1 is stopped, the intake and exhaust valves of the bank 1 are also stopped, so that the exhaust gas generated by the combustion of the air-fuel mixture and the evaporated fuel does not flow into the exhaust passage. In such a state, the concentration of the evaporated fuel calculated based on the detection value of the oxygen concentration sensor becomes a value close to zero and cannot be calculated accurately.
[0006]
When the operation of the bank 1 is resumed, the fuel supply amount supplied via the fuel injection valve and / or the purge control valve is used using the concentration of the evaporated fuel calculated when the bank 1 is stopped. The purge flow rate to be purged is corrected. As described above, the concentration of the evaporated fuel calculated when the bank 1 is stopped does not indicate an accurate value. As a result, even though evaporative fuel of the same concentration flows in the bank 1 and the bank 2, there is a “deviation” between the fuel supply amount / purge flow rate of the bank 1 and the fuel supply amount / purge flow rate of the bank 2. This causes a deviation in the air-fuel ratio between the banks.
[0007]
The present invention solves the above-described problems, and an object of the present invention is to provide a control device capable of estimating the concentration of evaporated fuel more accurately in consideration of cylinder deactivation control in an engine having a plurality of cylinder groups. Is to provide.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the invention of claim 1 is directed to an apparatus for controlling an internal combustion engine having a plurality of cylinder groups using the concentration of fuel evaporated from a fuel tank. Concentration estimating means for estimating the concentration of fuel evaporated from the fuel tank, cylinder deactivation means for deactivating operation of a predetermined cylinder group among the plurality of cylinder groups, and when the predetermined cylinder group is deactivated, a plurality of And a cylinder setting unit for idle cylinder that sets the vaporized fuel concentration estimated for the cylinder group that is operating among the cylinder groups to the vaporized fuel concentration of the cylinder group that is deactivated.
[0009]
According to the first aspect of the present invention, when the all-cylinder operation is resumed, the concentration estimated for the operating cylinder group is used as the evaporated fuel concentration for the inactive cylinder group. Since all-cylinder operation is resumed in a state where the evaporated fuel concentration of the cylinder group that has been stopped is set to an appropriate value, it is possible to prevent a “deviation” in engine control between the cylinder groups. As an example, when the fuel injection control is performed for each cylinder group, an appropriate fuel injection amount is calculated even for the cylinder group that has been stopped, and thus avoiding an air-fuel ratio shift between the cylinder groups. Can do.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of an internal combustion engine and its control device according to an embodiment of the present invention.
[0011]
An electronic control unit (hereinafter referred to as “ECU”) 5 includes an input interface 5a that receives data sent from each part of the vehicle, a CPU 5b that executes calculations for controlling each part of the vehicle, and a read-only memory (ROM) ) And a random access memory (RAM) 5c, and an output interface 5d for sending control signals to various parts of the vehicle. The ROM of the memory 5c stores a program for controlling each part of the vehicle and various data. A program for realizing engine control according to the present invention, and data and tables used in executing the program are stored in this ROM. The ROM may be a rewritable ROM such as an EPROM. The RAM is provided with a work area for calculation by the CPU 5b. Data sent from each part of the vehicle and control signals sent to each part of the vehicle are temporarily stored in the RAM.
[0012]
An internal combustion engine (hereinafter referred to as “engine”) 1 includes a plurality of cylinder groups. As an example, a V-type 6-cylinder engine is shown. A first cylinder group (hereinafter referred to as bank 1) 21 includes three cylinders (# 1 to # 3), and a second cylinder group (hereinafter referred to as bank 1). The bank 22 is also provided with three cylinders (# 4 to # 6).
[0013]
The engine 1 is provided with a cylinder deactivation mechanism 23. The cylinder deactivation mechanism 23 is hydraulically driven using the lubricating oil of the engine 1. The cylinder deactivation mechanism 23 is an all-cylinder operation in which all six cylinders in the first bank 21 and the second bank 22 are operated, and a cylinder deactivation operation in which fuel supply to the three cylinders in the first bank 21 is stopped. The engine 1 is switched between. When performing the cylinder deactivation operation, the cylinder deactivation mechanism 23 maintains the intake valves and exhaust valves of the three cylinders of the first bank 21 in the closed state.
[0014]
The intake passage 2 branches downstream of the throttle valve 3 into a passage 2 a reaching the bank 1 and a passage 2 b reaching the bank 2. Further, the passage 2a is branched into passages reaching the cylinders # 1 to # 3 of the bank 1, and the passage 2b is branched into passages reaching the cylinders # 4 to # 6 of the bank 2.
[0015]
The fuel injection valve 6 is provided for each cylinder in a passage leading to each cylinder. In the figure, only one fuel injection valve 6 is shown for simplicity. The fuel injection valve 6 has a valve opening time controlled by a control signal from the ECU 5.
[0016]
The fuel supply pipe 7 connects the fuel injection valve 6 and the fuel tank 9, and a fuel pump 8 provided in the middle supplies the fuel from the fuel tank 9 to the fuel injection valve 6. The air taken in through the throttle valve 3 passes through the intake passage 2 and is mixed with the fuel injected from the fuel injection valve 6 and supplied to each cylinder.
[0017]
A throttle valve 3 is disposed upstream of the intake passage 2. A throttle valve opening sensor (TH) 4 connected to the throttle valve 3 sends an electric signal corresponding to the opening of the throttle valve 3 to the ECU 5.
[0018]
An exhaust passage 12a is connected to the bank 1, and the gas discharged from the cylinder of the bank 1 flows into the exhaust passage 12a. An exhaust passage 12b is connected to the bank 2, and the gas discharged from the cylinders of the bank 2 flows into the exhaust passage 12b.
[0019]
Wide area air-fuel ratio sensors (LAF) sensors 13a and 13b are provided in the exhaust passages 12a and 12b, respectively. The LAF sensors 13a and 13b linearly detect the oxygen concentration in the exhaust gas in a wide range of air-fuel ratios ranging from lean to rich. The detected oxygen concentration is sent to the ECU 5.
[0020]
Downstream of the LAF sensors 13a and 13b, catalyst devices 14a and 14b for purifying harmful components in the exhaust gas are provided, respectively. O2 (exhaust gas) sensors 15a and 15b are provided downstream of the catalyst devices 14a and 14b. The O2 sensors 15a and 15b are binary exhaust gas concentration sensors. The O2 sensors 15a and 15b output a high level signal when the air-fuel ratio is richer than the stoichiometric air-fuel ratio, and output a low-level signal when the air-fuel ratio is leaner than the stoichiometric air-fuel ratio. The output electrical signal is sent to the ECU 5.
[0021]
The exhaust passages 12a and 12b merge with the exhaust passage 12 downstream of the O2 sensors 15a and 15b. Additional catalyst devices, LAF sensors, and O2 sensors may be provided in the exhaust passage 12.
[0022]
The ECU 5 includes an intake pipe pressure (Pb) sensor 16 that detects the pressure of air sucked into the engine 1, an intake air temperature (Ta) sensor 17 that detects the temperature of air sucked into the engine 1, and cooling water for the engine 1. An engine water temperature (Tw) sensor 18 that detects the temperature of the engine 1 and a rotation speed (Ne) sensor 19 that detects the rotation speed of the engine 1 are connected. Detection signals from these sensors are sent to the ECU 5.
[0023]
Next, the evaporative fuel processing system 30 will be described. The fuel tank 9 is connected to the canister 32 via the charge passage 31 so that the evaporated fuel from the fuel tank 9 can move to the canister 32. The charge passage 31 is provided with a mechanical two-way valve 33. The two-way valve 33 includes a positive pressure valve that opens when the tank internal pressure is higher than the atmospheric pressure by a first predetermined pressure or higher, and a negative pressure valve that opens when the tank internal pressure is lower than the canister 32 pressure by a second predetermined pressure or higher.
[0024]
A bypass passage 31b that bypasses the two-way valve is provided. A bypass valve 34 that is an electromagnetic valve is provided in the bypass passage 31b. The bypass valve 34 is normally in a closed state, and opens according to a control signal from the ECU 5.
[0025]
The pressure sensor 35 is provided between the two-way valve 33 and the fuel tank 9, and a detection signal thereof is sent to the ECU 5.
[0026]
The canister 32 incorporates activated carbon that adsorbs fuel vapor, and has an intake port (not shown) that communicates with the atmosphere via a passage 36. A vent shut valve 37 is provided in the middle of the passage 36. The vent shut valve 37 is an electromagnetic valve controlled by the ECU 5. The vent shut valve 37 is open when no drive signal is supplied.
[0027]
The canister 32 is connected to the downstream side of the throttle valve 3 via the purge passage 38. A purge control valve 39 that is an electromagnetic valve is provided in the middle of the purge passage 38, and the fuel adsorbed by the canister 32 is appropriately purged into the intake system of the engine via the purge control valve 39. The purge control valve 39 continuously controls the purge flow rate by changing the on-off duty ratio based on a control signal from the ECU 5.
[0028]
Input signals from various sensors are passed to the input interface 5a of the ECU 5. The input interface 5a converts an analog signal value into a digital signal value. The CPU 5b processes the converted digital signal, performs an operation according to a program stored in the ROM 5c, and generates a control signal to be sent to the actuator of each part of the vehicle. This control signal is sent to the output interface 5 d, and the output interface 5 d sends control signals to the fuel injection valve 6, the purge control valve 39, the bypass valve 34 and the vent shut valve 37.
[0029]
FIG. 2 schematically shows a hydraulic circuit for driving the cylinder deactivation mechanism 23. The intake side hydraulic control valve 41 and the exhaust side hydraulic control valve 42 are driven to open and close in accordance with a control signal from the ECU 5.
When the hydraulic control valves 41 and 42 are closed, the intake valves and exhaust valves of the cylinders (# 1 to # 3) included in the bank 1 are driven to open and close as usual, and all cylinder operation is performed. When the hydraulic control valves 41 and 42 are opened by a control signal from the ECU 5, hydraulic oil pressurized by the oil pump 43 is supplied to the cylinder deactivation mechanism 23. By the action of the hydraulic pressure, the intake valves and exhaust valves of the cylinders (# 1 to # 3) included in the bank 1 are maintained in the closed state, and the cylinder deactivation operation is performed.
[0030]
Various engine controls are controlled by the ECU 5, and these engine controls are typically performed for each bank. In this specification, as an example of control of an engine having a plurality of cylinder groups using the concentration of evaporated fuel, control of a fuel injection amount supplied via a fuel injection valve will be described. The fuel injection amount is controlled for each bank. In order to prevent an air-fuel ratio shift between the bank 1 and the bank 2, it is necessary to calculate an appropriate fuel injection amount for each of the bank 1 and the bank 2. In order to calculate an appropriate fuel injection amount, it is necessary to estimate the concentration of the evaporated fuel more accurately.
[0031]
First, an outline of a method for calculating the fuel injection amount will be described. The required fuel is calculated by multiplying the basic fuel amount TIM by a fuel injection coefficient (KTOTAL × KCMD × KAF) as shown in the equation (1). The required fuel is a fuel to be supplied to each cylinder of the engine.
[0032]
[Expression 1]
Required fuel = TIM x (KTOTAL x KCMD x KAF) (1)
[0033]
Here, the basic fuel amount TIM is specifically represented by a basic fuel injection time determined according to the engine speed NE and the intake pipe pressure PB. KTOTAL is a correction coefficient calculated based on detection signals from various sensors, and is set so that the fuel consumption characteristics and acceleration characteristics of the engine are optimized. KCMD is called a target air-fuel ratio coefficient, and represents the target air-fuel ratio as an equivalent ratio. The target air-fuel ratio coefficient KCMD is proportional to the reciprocal of the air-fuel ratio A / F, that is, the fuel-air ratio F / A, and takes a value of 1.0 when the stoichiometric air-fuel ratio.
[0034]
KAF represents an air-fuel ratio correction coefficient. In the air-fuel ratio feedback control, the air-fuel ratio correction coefficient KAF is calculated so that the air-fuel ratio of the air-fuel mixture supplied to the engine matches the target air-fuel ratio. The air-fuel ratio correction coefficient KAF is calculated based on the actual air-fuel ratio detected by the LAF sensor (LAF sensor 13a for bank 1 and LAF sensor 13b for bank 2).
[0035]
The amount of fuel to which the purge flow rate QPGC contributes to the required fuel (hereinafter referred to as purge correction amount) is calculated by multiplying the basic fuel amount TIM by the purge correction coefficient KAFEVACT, as shown in equation (2). The The purge flow rate QPGC indicates the amount of evaporated fuel purged into the engine intake system.
[0036]
[Expression 2]
Purge correction amount = TIM × KAFEVACT (2)
[0037]
The purge correction coefficient KAFEVACT is calculated based on the evaporated fuel concentration (hereinafter referred to as vapor concentration) KAFEV.
[0038]
From equations (1) and (2), the fuel injection amount TCYL supplied to the engine via the fuel injection valve is derived as in equation (3).
[0039]
[Equation 3]

[0040]
Since the purge correction coefficient KAFEVACT is calculated based on the vapor concentration coefficient KAFEV, it is necessary to estimate the vapor concentration coefficient KAFEV with good accuracy in order to calculate an appropriate fuel injection amount. With reference to FIG. 3, an outline of a method for calculating the vapor concentration coefficient KAFEV will be described in order to help understanding of the present invention.
[0041]
FIG. 3 shows the transition of the actual air-fuel ratio coefficient KACT with respect to the target air-fuel ratio coefficient KCMD, the transition of the air-fuel ratio correction coefficient KAF with respect to the purgeless air-fuel ratio learning value (hereinafter referred to as the purgeless learning value) KREFX, and the calculated vapor An example of transition of the density coefficient KAFEV is shown. Here, the purgeless learning value KREFX is a value obtained by averaging the air-fuel ratio coefficient KAF during the purge cut. As shown in FIG. 3, the high side determination value “KREFX + DKAFEVXH” and the low side determination value “KREFX−DKAFEVXL” are set with reference to the purgeless learning value KREFX.
[0042]
After the actual air-fuel ratio coefficient KACT exceeds the target air-fuel ratio coefficient KCMD at time t2, if the air-fuel ratio correction coefficient KAF falls below the low-side determination value “KREFX−DKAFEVXL” at time t3 to t4, It is determined that the air-fuel ratio has become rich with respect to the target air-fuel ratio. As a result, the vapor concentration coefficient KAFEV is calculated to increase from time t3 to t4.
[0043]
After the actual air-fuel ratio coefficient KACT falls below the target air-fuel ratio coefficient KCMD at time t5, when the air-fuel ratio correction coefficient KAF exceeds the high side determination value “KREFX + DKAFEVXH” at time t6 to t7, It is determined that the fuel ratio has become lean with respect to the target air-fuel ratio. As a result, the vapor concentration coefficient KAFEV is calculated to decrease from time t6 to time t7.
[0044]
At time t1 to t3, time t4 to t6, and time t7 to t9, the air-fuel ratio correction coefficient KAF is between the high side determination value “KREFX + DKAFEVXH” and the low side determination value “KREFX−DKAFEVXL”. The fact that the air-fuel ratio correction coefficient KAF is in this region indicates that the air-fuel ratio may be inclined to either rich or lean due to the influence of the evaporated fuel. When the air-fuel ratio correction coefficient KAF is in this region, the vapor concentration coefficient KAFEV is corrected according to the difference between the purgeless learning value KREFX and the purged air-fuel ratio learning value (hereinafter referred to as purged learning value) KREF. The Here, the purged learning value KREF is a value obtained by averaging the air-fuel ratio correction coefficient KAF while purging is being performed.
[0045]
Thus, since the vapor concentration coefficient KAFEV is calculated by estimation, an error may be included depending on the operating state. This error is represented by the difference between the purged learning value KREF and the purgeless learning value KREFX. This is because if the vapor concentration coefficient KAFEV is correct, the learning value KREF with purge and the learning value KREFX without purge show the same value.
[0046]
FIG. 4 is a functional block diagram of the control device according to the present invention. The function represented by each functional block is typically executed by a computer program. Alternatively, each functional block may be realized by arbitrary hardware configured to execute the function represented by each functional block.
[0047]
Each functional block implements a predetermined function for each bank. The following calculation formulas are executed for each of bank 1 and bank 2 unless otherwise specified.
[0048]
The intake air amount calculation unit 51 calculates the intake air amount QAIR based on the equation (4).
[0049]
[Expression 4]
QAIR = TIM × NE × 2 × KQAIR × KPA (4)
[0050]
As described above, TIM indicates the basic fuel injection amount. KQAIR is a coefficient for converting the fuel injection amount into the air flow rate, and has a fixed value (for example, 0.45 L / ms). KPA is a coefficient for correcting the fluctuation of the flow rate according to the intake pipe pressure PB.
[0051]
The intake air amount calculation unit 51 further calculates the ratio of the evaporated fuel to the intake air amount QAIR, that is, the basic purge amount QPGCBASE based on the equation (5).
[0052]
[Equation 5]
QPGCBASE = QAIR × KQPGB (5)
[0053]
Here, KQPGB indicates a target purge rate, for example, 0.04. In this case, the evaporated fuel is included in 4% of the intake air amount QAIR.
[0054]
Next, the purge flow rate calculation unit 52 calculates the target purge flow rate QPGCMD based on the formula (6) based on the basic purge amount QPGCBASE. The target purge flow rate QPGCMD represents the target value of the purge flow rate purged into the engine intake system in the current cycle.
[0055]
[Formula 6]
QPGCMD = QPGCBASE × KPGT (6)
[0056]
KPGT is a purge flow coefficient and has a value of 1 or less. By controlling this coefficient KPGT, the amount of the target purge flow rate QPGCMD can be controlled.
[0057]
In one embodiment, the coefficient KPGT is increased by a predetermined amount every cycle. The timing for executing this increasing process is determined based on the vapor concentration KAFEV and the intake air amount QAIR. The larger the vapor concentration coefficient KAFEV and the smaller the intake air amount QAIR, the longer the time interval for performing the increase process, so that the target purge flow rate QPGCMD increases more gradually.
[0058]
The process of increasing the coefficient KPGT is performed, for example, as long as the fuel amount contributed by the purge flow rate does not exceed a predetermined upper limit value. As a result, as much vaporized fuel as possible can be supplied to the engine so as not to affect the air-fuel ratio feedback control.
[0059]
Further, the purge flow rate calculation unit 52 calculates the purge flow rate QPGC purged in the current cycle based on the intake air amount QAIR based on the equation (7).
[0060]
[Expression 7]
QPGC (k) = QPGC (k−1) + (QAIR × KDQPGC) (7)
[0061]
Here, k is a number for identifying the cycle, (k) indicates the current cycle, and (k-1) indicates the previous cycle. KDQPGC is a predetermined fixed value (for example, 0.003). As shown in Expression (7), the purge flow rate QPGC is controlled so as to gradually reach the target purge flow rate QPGCMD.
[0062]
The duty calculator 53 calculates the duty ratio PGCMD for driving the purge control valve based on the equation (8) so that the purge flow QPGC received from the purge flow calculator 52 is purged. The duty ratio represents a ratio at which the purge control valve is opened.
[0063]
[Equation 8]

[0064]
KDUTY is a coefficient for converting the purge flow rate into a duty ratio, and has a fixed value (for example, 3.8% · min / L). KDPBG is a coefficient for correcting the opening of the purge control valve according to the differential pressure. PGCMD0 represents a duty ratio corresponding to the purge flow rate QPGC, and is called a target duty ratio. Depending on battery voltage VB and intake pipe pressure PB, there will be some delay before the purge control valve begins to open. DPGCVBX and DPGC0 are coefficients for correcting this delay (hereinafter referred to as invalid time).
[0065]
The duty calculation unit 53 performs limit processing on the duty ratio PGCMD with a predetermined upper limit value and lower limit value, and outputs a final duty ratio DOUTPGC. Thus, the opening degree of the purge control valve is controlled according to the final duty ratio DOUTPGC.
[0066]
The air-fuel ratio control unit 54 calculates the air-fuel ratio coefficient KAF based on the output from the LAF sensor (LAF sensor 13a for bank 1 and LAF sensor 13b for bank 2) so as to converge the air-fuel ratio to the target air-fuel ratio. The calculated feedback control is performed for each bank.
[0067]
The air-fuel ratio learning value calculation unit 55 calculates the purged learning value KREF and the non-purging learning value KREFX based on the equation (9) based on the air-fuel ratio coefficient KAF calculated by the air-fuel ratio control unit 54. .
[0068]
[Equation 9]

[0069]
#CREF and #CREFX are predetermined values representing weighting coefficients, respectively. This value determines how much the air-fuel ratio correction coefficient KAF is reflected in KREF (k-1) and KREFX (k-1) calculated in the previous cycle.
[0070]
The cylinder deactivation control unit 56 transmits a control signal to the hydraulic control valves 41 and 42 (FIG. 2), and causes the cylinder deactivation mechanism 23 to deactivate the cylinders # 1 to # 3 included in the bank 1. The cylinder deactivation control unit 56 sets the value of the flag F_CSTP to 1 when starting the cylinder deactivation operation.
[0071]
The vapor concentration coefficient calculation unit 57 estimates the vapor concentration coefficient KAFEV based on the air-fuel ratio correction coefficient KAF calculated by the air-fuel ratio control unit 54 and the learning values KREFX and KREF calculated by the air-fuel ratio learning value calculation unit 55. .
[0072]
The vapor concentration coefficient calculation unit 57 further checks the cylinder deactivation flag F_CSTP set by the cylinder deactivation control unit 56. When the value of the flag F_CSTP is 1, it indicates that the cylinders included in the bank 1 are inactive. When the value of the flag F_CSTP is 1, the vapor concentration coefficient calculation unit 57 substitutes the vapor concentration coefficient KAFEV estimated for the bank 2 (that is, the operating cylinder group) into the vapor concentration coefficient of the bank 1. Thus, when the bank 1 resumes operation, the fuel injection amount of the bank 1 is calculated using the substituted vapor concentration coefficient KAFEV.
[0073]
The transport delay calculation unit 58 calculates a purge transport delay CPGDLYRX based on the engine speed NE. The purge transport delay CPGDLYRX indicates a time delay from when the evaporated fuel is purged to the purge passage until it is sent to the intake system of the engine. The purge transport delay CPGDLYRX is represented by an integer n, and indicates that the transport delay increases as n increases. Alternatively, the purge transport delay may be calculated based on the intake air amount QAIR instead of the engine speed NE.
[0074]
The target purge correction coefficient calculation unit 59 calculates a target purge correction coefficient KAFEVACZ based on Expression (10).
[0075]
[Expression 10]

[0076]
PGRATE and QRATE are expressed by equations (11) and (12).
[0077]
[Expression 11]

[0078]
“PGRATE × QRATE” indicates the ratio of the purge flow rate purged to the engine intake system in the current cycle to the purge flow rate that can be included in the required fuel (represented by equation (1)). Since the fuel is expressed depending on the vapor concentration coefficient KAFEV, the target purge correction coefficient KAFEVACZ is calculated by multiplying “PGRATE × QRATE” by the vapor concentration coefficient KAFEV as shown in the equation (10). Can do.
[0079]
The target purge correction coefficient calculation unit 59 has a plurality of buffers assigned numbers 0 to (n−1), and stores the target purge correction coefficient calculated in the current cycle in the zeroth buffer. The target purge correction coefficient calculated in the previous cycle is stored in the first buffer,. . . Thus, the target purge correction coefficient is stored in time series.
[0080]
The target purge correction coefficient calculation unit 59 receives the value n of the transport delay CPGDLYRX of the evaporated fuel from the transport delay calculation unit 58, and extracts the target purge correction coefficient KAFEVACZ from the numbered buffer corresponding to the n. For example, if the value n of CPGDLYRX received is 3, the target purge correction coefficient KAFEVACZ is extracted from the third buffer.
[0081]
The purge correction coefficient calculation unit 60 calculates the purge correction coefficient KAFEVACT based on Expression (13).
[0082]
[Expression 12]
KAFEVACT = KAFEVACZ × KKEVG (13)
[0083]
KKEVG represents a high concentration correction coefficient, and is a coefficient for correcting the influence on the air-fuel ratio when the concentration of the evaporated fuel is very high. The high concentration correction coefficient KKEVG is set to a value greater than 1 according to the concentration of the evaporated fuel.
[0084]
As described above, the purge correction coefficient KAFEVACT indicates the ratio of the fuel amount to which the purge flow rate QPGC contributes to the required fuel. The ratio of the fuel amount contributed by the purge flow rate QPGC is first calculated as the target purge correction coefficient KAFEVACZ, and is corrected by multiplying it by the high concentration correction coefficient KKEVG, and finally set to the purge correction coefficient KAFEVACT.
[0085]
The fuel injection amount calculation unit 61 receives the purge correction coefficient KAFEVACT from the purge correction coefficient calculation unit 60, and calculates the fuel injection amount TCYL according to the above equation (3). The fuel injection amount TCYL calculated for each bank is supplied to the bank via the fuel injection valve. Thus, an amount of fuel obtained by subtracting the amount of evaporated fuel (that is, the purge correction amount) contributed by the purge flow rate QPGC is supplied to the engine via the fuel injection valve.
[0086]
FIG. 5 is a flowchart for determining the conditions for calculating the vapor concentration coefficient KAFEV for the bank 1. The actual air-fuel ratio coefficient KAF is a value based on the detection value of the LAF sensor 13a for the bank 1. This flowchart is repeatedly executed at regular time intervals.
[0087]
In steps S101 and S102, the DKAFEVXH / DKAFEVXL table is accessed to obtain a high side determination value DKAFEVXH and a low side determination value DKAFEVXL (see FIG. 2) based on the intake air amount QAIR. FIG. 8 shows an example of this table. The high side and low side determination values DKAFEVXH and DKAFEVXL are set to decrease as the intake air amount QAIR increases.
[0088]
In step S103, the value obtained by subtracting the low-side determination value DKAFEVXL from the air-fuel ratio learned value KREFX is greater than the air-fuel ratio correction coefficient KAF, and in step S104, the actual air-fuel ratio coefficient KACT is greater than the target air-fuel ratio coefficient KCMD. For example, the air-fuel ratio is in a rich state with respect to the target air-fuel ratio due to the influence of the evaporated fuel. In such a state, a value 1 is set to the flag F_KAFEVP (S105). A flag F_KAFEVP in which the value 1 is set indicates a state in which the vapor concentration coefficient KAFEV should be increased.
[0089]
If the value obtained by adding the high-side determination value DKAFEVXH to the air-fuel ratio learning value KREFX is smaller than the air-fuel ratio correction coefficient KAF (S107) and the actual air-fuel ratio coefficient KACT is smaller than the target air-fuel ratio coefficient KCMD (S108). It shows that the air-fuel ratio is lean with respect to the target air-fuel ratio due to the influence of the evaporated fuel. In such a state, the flag F_KAFEVM is set to a value 1 (S109). A flag F_KAFEVM in which the value 1 is set indicates a state in which the vapor concentration coefficient KAFEV should be reduced.
[0090]
When the determination steps of both steps S103 and S107 are No, it indicates that the air-fuel ratio correction coefficient KAF is between the high side determination value DKAFEVXH and the low side determination value DKAFEVXL (see FIG. 2). If the learned value KREF with purge is smaller than the learned value KREFX without purge, the process proceeds to step S111, and if the learned value KREF is greater than or equal to the learned value KREFX, the process proceeds to step S115.
[0091]
If the air-fuel ratio correction coefficient KAF is smaller than the learned value KREFX in step S111 and the actual air-fuel ratio KACT is larger than the target air-fuel ratio KCMD in step S112, it indicates that the air-fuel ratio is leaning to the rich side due to the purge. In this case, a value of 1 is set in the flag F_KAFEVC. The flag F_KAFEVC in which the value 1 is set indicates a state in which the vapor concentration coefficient KAFEV should be corrected according to the difference between the learning values KREF and KREFX (S113).
[0092]
On the other hand, if the air-fuel ratio correction coefficient KAF is larger than the learned value KREFX in step S115 and the actual air-fuel ratio KACT is smaller than the target air-fuel ratio KCMD in step S116, it indicates that the air-fuel ratio is leaning toward the lean side. Also in this case, a value 1 is set to the flag F_KAFEVC (S117).
[0093]
In other states, all the flags are set to zero (S106 and S114), and the vapor concentration coefficient KAFEV is not updated.
[0094]
The same processing as in the flowchart shown in FIG. In this case, as the actual air-fuel ratio coefficient, the purgeless learning value, and the purged learning value, values calculated based on the detection value of the LAF sensor 13b for the bank 2 are used. For bank 2, instead of flags F_KAFEVP, F_KAFEVM and F_KAFEVC, flags F_KAFEVB2P, F_KAFEVB2M and flag F_KAFEEVB2C are set.
[0095]
FIG. 6 is a flowchart for calculating the vapor concentration coefficient KAFEV. This flowchart is repeatedly executed at regular time intervals. In this flowchart, KAFEV represents the vapor concentration coefficient for bank 1, and KAFEVB2 represents the vapor concentration coefficient for bank 2. KREFX and KREF indicate a purgeless learning value and a purged learning value calculated based on the detection value of the LAF sensor 13a provided for bank 1, respectively. KREFXB2 and KREFB2 are LAF provided for bank 2, respectively. The purgeless learning value and the purged learning value calculated based on the detection value of the sensor 13b are respectively shown.
[0096]
In step S201, it is determined whether air-fuel ratio feedback control is currently being executed. If the feedback control is not in progress, this routine is exited. In step S202, if the purge flow rate QPGC is zero, it indicates that the evaporated fuel is not purged in the current cycle, so this routine is exited. If the purge flow rate QPGC is not zero, the process proceeds to step S203.
[0097]
In step S203, the value of the flag F_KAFEVB2P of the bank 2 is checked. As described above with reference to step S105, if the value of the flag F_KAFEVB2P is 1, it indicates that the air-fuel ratio is in a rich state. In step S204, the vapor concentration coefficient KAFEVB2 of the bank 2 is increased by a predetermined value DKEVAPOP (for example, 0.05).
[0098]
In step S205, the value of the flag F_KAFEVB2M of the bank 2 is checked. As described above with reference to step S109, if the value of the flag F_KAFEVB2M is 1, it indicates that the air-fuel ratio is in a lean state. In step S206, the vapor concentration coefficient KAFEVB2 of the bank 2 is decreased by a predetermined value DKEVAPOM (for example, 0.08).
[0099]
In step S207, the value of the flag F_KAFEVB2C of the bank 2 is checked. As described above with reference to steps S113 and S117, if the value of the flag F_KAFEVB2C is 1, it indicates that the air-fuel ratio is leaning to a rich or lean state. Proceeding to step S208, the vapor concentration coefficient KAFEVB2 is calculated according to the difference between the learned values KREFB2 and KREFXB2. That is, the vapor concentration coefficient KAFEVB2 is updated by adding a value obtained by subtracting the purged KREFB2 from the purgeless learning value KREFXB2 and a predetermined value CAFEV (for example, 0.02).
[0100]
For bank 2, since KREFB2 <KREFXB2 in the case of step S113 in FIG. 5, the vapor concentration coefficient KAFEVB2 is increased by the update process in step S208. In the case of step S117 in FIG. 5, since KREFB2> KREFXB2, the vapor concentration coefficient KAFEVB2 is reduced by the update process in step S208. When the determination in step S207 is No, the vapor concentration coefficient KAFEVB2 is not updated.
[0101]
In step S209, the value of the cylinder deactivation flag F_CSTP is checked. If the value of F_CSTP is 1, it indicates that the cylinders included in bank 1 are inactive. In step S210, the vapor concentration coefficient KAFEVB2 calculated for the bank 2 is set in the vapor concentration coefficient KAFEV for the bank 1.
[0102]
In step S211, the value of the flag F_KAFEVP of the bank 1 is checked. Similarly to step S203, if the value of the flag F_KAFEVP is 1, the vapor concentration coefficient KAFEV of the bank 1 is increased by a predetermined value DKEVAPOP (for example, 0.05) (S212).
[0103]
In step S213, the value of the flag F_KAFEVM of the bank 1 is checked. Similarly to step S205, if the value of the flag F_KAFEVM is 1, the vapor concentration coefficient KAFEV of the bank 1 is decreased by a predetermined value DKEVAPOM (for example, 0.08) (S214).
[0104]
In step S215, the value of the flag F_KAFEVC of the bank 1 is checked. Similarly to step S207, if the value of the flag F_KAFEVC is 1, the vapor concentration coefficient KAFEV is obtained by adding a value obtained by multiplying the learned value KREFX by subtracting KREF and a predetermined value CAFEV (for example, 0.02). Update (S216). If the determination in step S215 is No, the vapor concentration coefficient KAFEV is not updated.
[0105]
Thus, as shown in step S210, when the operation of the cylinder group of the bank 1 is stopped, the vapor concentration calculated for the cylinder group of the operating bank 2 is set in the cylinder group of the bank 1. The When the operation of the cylinder group of bank 1 is resumed, the vapor concentration set in this way is used for calculating the purge correction amount and the fuel injection amount for the cylinder group of bank 1. Since all cylinder operation is resumed in a state where appropriate vapor concentrations are set for all cylinders, it is possible to avoid the occurrence of an air-fuel ratio shift between the cylinders when all cylinder operation is resumed.
[0106]
FIG. 7 is a flowchart for calculating the purge correction coefficient KAFEVACT for correcting the fuel injection amount for the bank 1 using the estimated vapor concentration coefficient KAFEV. This flowchart is repeatedly executed at regular time intervals.
[0107]
In step S301, a purge flow rate QRATE is obtained. This is calculated according to the equation (12) described above.
[0108]
In step S302, the purge transport delay table CPGDLYRX is accessed, and the purge transport delay CPGDLYRX is obtained based on the engine speed NE. As described above, the purge transport delay CPGDLYRX indicates a time delay from when the evaporated fuel is purged to the purge passage via the purge control valve until it reaches the intake system of the engine. In this embodiment, the purge transport delay CPGDLYRX is represented by the integer n. FIG. 9 shows an example of the purge transport delay table CPGDLYRX table. The purge transport delay table CPGDLYRX table is set so that the purge transport delay CPGDLYRX increases as the rotation NE increases. This is because the larger the engine speed NE, the greater the number of intake steps that are performed after the evaporated fuel is purged until it reaches the engine intake system.
[0109]
In step S303, the ring buffer is shifted by one. The ring buffer is composed of, for example, 16 buffers KAFEVRT0 to KAFEVRTf. Shifting the ring buffer indicates shifting the data stored in KAFEVRT0 to KAFEVRTe to KAFEVRT1 to KAFEVRTf, respectively. Data stored in KAFEVRTf is discarded. Thus, KAFEVRT0 is emptied.
[0110]
In step S304, a value obtained by multiplying the purge flow rate QRATE by the duty rate PGRATE calculated according to the equation (11) is stored in the buffer KAFEVRT0. Thus, “PGRATE × QRATE” calculated in the current cycle is stored in the zeroth buffer. First, second,. . . , Respectively (ie, KAFEVRT1, KAFEVRT2,...), Respectively,. . . “PGRATE × QRATE” calculated in this cycle is stored.
[0111]
Proceeding to step S305, the target purge correction coefficient KAFEVACZ is obtained according to the above-described equation (10). Specifically, the target purge correction coefficient KAFEVACZ is calculated by multiplying the vapor concentration coefficient KAFEV by KAFEVRTn corresponding to the purge transport delay value n obtained in step 302. For example, if the purge transport delay CPGDLYRX is “4”, the value of KAFEVRT stored in the buffer KAFEVRT4 is used.
[0112]
Steps S306 to S309 indicate processing for calculating the high density correction coefficient KKEVG. In step S306, the vapor concentration coefficient KAFEV is compared with the guard coefficient KEVACTG. The guard coefficient KEVACTG is a coefficient calculated according to the driving state. If the vapor concentration coefficient KAFEV is larger than the guard coefficient KEVACTG, it indicates that the concentration of the evaporated fuel is very high. In step S307, “KAFEV / KEVACACTG” is calculated to obtain a high concentration coefficient KKEVG.
[0113]
On the other hand, if the vapor concentration coefficient KAFEV is smaller than the guard coefficient KEVACTG, it indicates that the concentration of the evaporated fuel is not so large as to be corrected. In step S308, 1 is set to the high density correction coefficient KKEVG.
[0114]
Proceeding to step S309, as shown in equation (13), the target purge correction coefficient KAFEVACZ is multiplied by the high concentration coefficient KKEVG obtained in step S307 or S308 to obtain the purge correction coefficient KAFEVACT.
[0115]
For bank 2, the same processing as in FIG. The purge correction coefficient for bank 2 is calculated using the vapor concentration coefficient KAFEVB2 for bank 2.
[0116]
As described above, according to the present invention, the vapor concentration is calculated in consideration of the cylinder deactivation operation. Since the fuel injection amount is calculated based on the calculated vapor concentration, it is possible to avoid the deviation of the air-fuel ratio between the cylinder groups even when the cylinder deactivation control is performed.
[0117]
The vapor concentration calculated in this manner can of course be used for the calculation of the purge flow rate QPGC described with reference to FIG. Furthermore, the vapor concentration calculated in this way can be used for another engine control for an engine having a plurality of cylinder groups.
[0118]
In the above embodiment, the example using the LAF sensor is shown, but the present invention can also be applied to the case where the O2 sensor is used. Based on the detection value of the O2 sensor, air-fuel ratio feedback control can be performed for each cylinder group.
[0119]
The present invention can also be applied to a marine vessel propulsion engine such as an outboard motor having a vertical crankshaft.
[0120]
【The invention's effect】
According to the present invention, even when cylinder deactivation operation is performed in an engine having a plurality of cylinders, the engine can be controlled in a state where an appropriate vapor concentration is set for each cylinder group.
[Brief description of the drawings]
FIG. 1 schematically shows an internal combustion engine and a control device according to one embodiment of the present invention.
FIG. 2 is a diagram showing a circuit for driving a cylinder deactivation mechanism according to one embodiment of the present invention.
FIG. 3 is a diagram showing an example of a temporal transition of an actual air-fuel ratio coefficient, an air-fuel ratio correction coefficient, and a vapor concentration according to one embodiment of the present invention.
FIG. 4 is a functional block diagram of a control device according to one embodiment of the present invention.
FIG. 5 is a flowchart for determining a calculation condition of a vapor concentration coefficient KAFEV according to one embodiment of the present invention.
FIG. 6 is a flowchart for calculating a vapor concentration coefficient KAFEV according to one embodiment of the present invention.
FIG. 7 is a flowchart for calculating a purge correction coefficient KAFEVACT according to one embodiment of the present invention.
FIG. 8 is a diagram showing a table for obtaining high-side and low-side determination values DKAFEVXH and DKAFEVXL according to one embodiment of the present invention.
FIG. 9 is a diagram showing a CPGDLYRX table for determining purge transport delay according to one embodiment of the present invention.
[Explanation of symbols]
1 engine
5 ECU
23 cylinder deactivation mechanism

Claims (1)

A device for controlling an internal combustion engine having a plurality of cylinder groups using the concentration of fuel evaporated from a fuel tank,
Concentration estimating means for estimating the concentration of fuel evaporated from the fuel tank for each of the plurality of cylinder groups;
Cylinder stopping means for stopping operation of a predetermined cylinder group among the plurality of cylinder groups;
When the predetermined cylinder group is deactivated, the concentration of the evaporated fuel estimated by the concentration estimating means for the cylinder group that is operating among the plurality of cylinder groups is determined by the evaporation of the deactivated cylinder group. A concentration setting means for the idle cylinder for setting the fuel concentration;
An internal combustion engine control device comprising:

Images