JP2004108204A

JP2004108204A - Control device for internal combustion engine

Info

Publication number: JP2004108204A
Application number: JP2002270008A
Authority: JP
Inventors: Shigehiko Tajima; 田島　薫彦
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2002-09-17
Filing date: 2002-09-17
Publication date: 2004-04-08

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate torque fluctuation between cylinders by adequately correcting the ignition timing or the fuel injection quantity based on the change of the air intake pressure of each cylinder of an internal combustion engine. <P>SOLUTION: A cylinder of the largest change is specified from the change of the air intake pressure of the average intake pressure of each cylinder obtained by averaging the intake pressure PM of an internal combustion engine 1 comprising three cylinders for each combustion interval of 240 [degrees CA (Crank Angle)] associated with the rotation of a crank shaft 13 and the change of the intake pressure in 720 [degrees CA] which is the total of the change of the intake pressure for all cylinders, and the ignition timing is advanced or delayed for this cylinder. The fuel injection is increased or decreased for the cylinder specified to be largest in the change of the intake pressure. Torque fluctuation between cylinders can be suitably eliminated by correcting the ignition timing and the fuel injection. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、内燃機関の点火時期や燃料噴射量を補正することで気筒間のトルク変動をなくす内燃機関用制御装置に関するものである。
【０００２】
【従来の技術】
従来、内燃機関用制御装置に関連する先行技術文献としては、特公平８−３３１１７号公報にて開示されたものが知られている。このものでは、吸気圧データの平均値の変化量に基づく加速状態等の過渡状態に対応する過渡補正燃料増量と、クランク角信号及び吸気圧データの平均値に基づく基本燃料量とから燃料噴射量を算出する技術が示されている。
【０００３】
【発明が解決しようとする課題】
ところで、前述のものでは、吸気圧データの平均値の変化量に対し、不感帯を設け過渡時における補正燃料増量の基本燃料量への不適切な加算を禁止している。ここにおいて、全気筒同時（７２０〔°ＣＡ（Ｃｒａｎｋ　Ａｎｇｌｅ：クランク角）〕毎）に燃料噴射するシステムについて説明されているが、現在では気筒毎（３気筒の場合２４０〔°ＣＡ〕毎）に独立して燃料噴射するシステムが一般的になっている。例えば、ドライバ（運転者）がアクセルペダルを踏込むことにより吸気圧データの変化量が不感帯を越えると、加速増量が行われる。その後、ドライバがアクセルペダルを踏込んだときのアクセル開度に保ち、加速を続け徐々に回転が上昇した場合、特定の回転速度域で吸気慣性効果により吸気脈動が拡大することとなる。
【０００４】
各気筒毎（３気筒の場合２４０〔°ＣＡ〕毎）に燃料噴射量を演算し、独立して燃料噴射するシステムにおいては前述の吸気脈動の拡大により、吸気圧データの変化量が不感帯を越えてしまい、吸気脈動の大きな気筒に対して、燃焼毎の圧力変化を捉えて増減量を行うため、特定の気筒に増量または減量がなされることとなり、増量される気筒と減量される気筒とでトルク差が拡大し、ドライバビリティを悪化させるという不具合があった。
【０００５】
そこで、この発明はかかる不具合を解決するためになされたもので、内燃機関の各気筒の吸気圧変化量に基づき点火時期や燃料噴射量を適切に補正することで気筒間のトルク変動を解消可能な内燃機関用制御装置の提供を課題としている。
【０００６】
【課題を解決するための手段】
請求項１の内燃機関用制御装置によれば、気筒特定手段によって吸気圧検出手段で検出された複数気筒からなる内燃機関の吸気通路内のスロットルバルブ下流側の吸気圧を、回転角検出手段で検出されたクランクシャフトまたはカムシャフトの回転角に基づく燃焼間隔毎に平均化した各気筒の平均吸気圧の吸気圧変化量と、この吸気圧変化量の全気筒分の総和である吸気圧変化量とから最も変化の大きな気筒が特定され、この気筒に対し変動補正手段によって点火時期が進角または遅角される。この点火時期の補正により、気筒間のトルク変動が好適に解消されるという効果が得られる。
【０００７】
請求項２の内燃機関用制御装置によれば、気筒特定手段によって吸気圧検出手段で検出された複数気筒からなる内燃機関の吸気通路内のスロットルバルブ下流側の吸気圧を、回転角検出手段で検出されたクランクシャフトまたはカムシャフトの回転角に基づく燃焼間隔毎に平均化した各気筒の平均吸気圧の吸気圧変化量と、この吸気圧変化量の全気筒分の総和である吸気圧変化量とから最も変化の大きな気筒が特定され、この気筒に対し変動補正手段によって燃料噴射量が増量または減量される。この燃料噴射量の補正により、気筒間のトルク変動が好適に解消されるという効果が得られる。
【０００８】
請求項３の内燃機関用制御装置によれば、気筒特定手段によって吸気圧検出手段で検出された複数気筒からなる内燃機関の吸気通路内のスロットルバルブ下流側の吸気圧を、回転角検出手段で検出されたクランクシャフトまたはカムシャフトの回転角に基づく燃焼間隔毎に平均化した各気筒の平均吸気圧の吸気圧変化量と、この吸気圧変化量の全気筒分の総和である吸気圧変化量とから最も変化の大きな気筒が特定され、更に、振動検出手段による振動波形信号に基づくノック判定手段によるノック発生の有無の判定結果に基づき、特定された気筒に対し点火時期が進角または遅角される。この点火時期の補正により、気筒間のトルク変動が好適に解消されるという効果が得られる。
【０００９】
請求項４の内燃機関用制御装置によれば、気筒特定手段によって吸気圧検出手段で検出された複数気筒からなる内燃機関の吸気通路内のスロットルバルブ下流側の吸気圧を、回転角検出手段で検出されたクランクシャフトまたはカムシャフトの回転角に基づく燃焼間隔毎に平均化した各気筒の平均吸気圧の吸気圧変化量と、この吸気圧変化量の全気筒分の総和である吸気圧変化量とから最も変化の大きな気筒が特定され、更に、空燃比検出手段による内燃機関の排気通路内における排出ガスの空燃比の検出結果に基づき、特定された気筒に対し燃料噴射量が増量または減量される。この燃料噴射量の補正により、気筒間のトルク変動が好適に解消されるという効果が得られる。
【００１０】
請求項５の内燃機関用制御装置では、内燃機関が排気タービン過給機を備え、排気圧を利用してタービンを回転させ、このタービンが回転することによって燃焼室に吸入空気を大量に送込むシステムに適用される。ドライバがアクセルペダルを踏込み、その後アクセルペダルの踏込量を保持したときに、吸気脈動が拡大するという現象は特に、排気タービン過給機を備えたシステムにおいて顕著に現われる。排気タービン過給機を備えたシステムでは、排気圧を利用してタービンを回転させ、このタービンが回転することによって燃焼室に吸入空気を大量に送り込むシステムになっている。つまり、ドライバがアクセルペダルを踏込み、その後アクセルペダルの踏込量を保持したとき、機関回転速度の上昇が少なくても、タービンの回転が上昇し過給効果で吸気量が増大する。これにより、機関回転速度とタービン回転が干渉し、気筒毎の変動周波数と同調することで吸気脈動として大きな変動を発生する現象がある。そこで、内燃機関に排気タービン過給機を備えたシステムに適用すると大きな効果が期待できる。
【００１１】
【発明の実施の形態】
以下、本発明の実施の形態を実施例に基づいて説明する。
【００１２】
〈実施例１〉
図１は本発明の実施の形態の第１実施例にかかる内燃機関用制御装置が適用された内燃機関及びその周辺機器を示す概略構成図である。
【００１３】
図１において、１は複数気筒の例えば、４サイクル３気筒からなる内燃機関であり、内燃機関１の吸気通路２にはエアクリーナ３からの空気が導入される。この吸気通路２途中には、ドライバ（運転者）の要求として図示しないアクセルペダル等の操作に連動して開閉されるスロットルバルブ１１が配設されている。このスロットルバルブ１１が開閉されることにより、吸気通路２への吸気量が調節される。また、この吸気量と同時に、図示しない燃料タンクから燃料ポンプにて圧送されプレッシャレギュレータを介して調圧された燃料が、内燃機関１の吸気ポート４の近傍で吸気通路２に配設されたインジェクタ（燃料噴射弁）５から噴射供給される。そして、所定の燃料量及び吸気量からなる混合気が吸気バルブ６を介して燃焼室７内に吸入される。
【００１４】
吸気通路２途中のスロットルバルブ１１にはアクセルペダル踏込量等に応じたスロットル開度ＴＨＲを検出するスロットル開度センサ２１が配設されている。また、スロットルバルブ１１の下流側には、吸気通路２内の吸気圧ＰＭを検出する吸気圧センサ２２が配設されている。そして、内燃機関１のクランクシャフト１３にはその回転に伴うクランク角〔°ＣＡ（Ｃｒａｎｋ　Ａｎｇｌｅ）〕を検出するクランク角センサ２３が配設されている。このクランク角センサ２３で検出されるクランク角に基づき内燃機関１の機関回転数ＮＥが算出される。
【００１５】
また、内燃機関１の燃焼室７内に向けて点火プラグ１４が配設されている。この点火プラグ１４にはクランク角センサ２３で検出されるクランク角に同期して後述のＥＣＵ（Ｅｌｅｃｔｒｏｎｉｃ　Ｃｏｎｔｒｏｌ　Ｕｎｉｔ：電子制御ユニット）３０から出力される点火指令信号に基づき点火コイル／イグナイタ１５からの高電圧が印加され、燃焼室７内の混合気に対する点火燃焼が行われる。このように、燃焼室７内の混合気が燃焼（膨張）され駆動力が得られ、この燃焼後の排出ガスは、排気バルブ８を介して排気マニホールドから排気通路９に導出され外部に排出される。
【００１６】
ＥＣＵ３０は、周知の各種演算処理を実行する中央処理装置としてのＣＰＵ３１、制御プログラムを格納したＲＯＭ３２、各種データを格納するＲＡＭ３３、Ｂ／Ｕ（バックアップ）ＲＡＭ３４、入出力回路３５及びそれらを接続するバスライン３６等からなる論理演算回路として構成されている。このＥＣＵ３０には、スロットル開度センサ２１からのスロットル開度ＴＨＲ、吸気圧センサ２２からの吸気圧ＰＭ、クランク角センサ２３からのクランクシャフト１３の回転角や機関回転速度ＮＥ等が入力されている。これら各種センサ情報に基づくＥＣＵ３０からの出力信号に基づき、燃料噴射時期及び燃料噴射量に関連するインジェクタ５、点火時期に関連する点火プラグ１４、点火コイル／イグナイタ１５等が適宜、制御される。
【００１７】
次に、本発明の実施の形態の第１実施例にかかる内燃機関用制御装置で使用されているＥＣＵ３０内のＣＰＵ３１における気筒特定の処理手順を示す図２のフローチャートに基づいて説明する。なお、この気筒特定ルーチンは４サイクル３気筒からなる内燃機関１の各気筒の燃焼（点火）間隔である２４０〔°ＣＡ〕毎にＣＰＵ３１にて繰返し実行される。
【００１８】
図２において、ステップＳ１０１では、吸気圧センサ２２からの吸気圧ＰＭを燃焼間隔毎に平均化した２４０〔°ＣＡ〕間の平均吸気圧ＰＭ２が算出される。次にステップＳ１０２に移行して、ステップＳ１０１で算出された平均吸気圧ＰＭ２の前回値と今回値との差分である２４０〔°ＣＡ〕間の吸気圧変化量ＤＰＭ２が算出される。次にステップＳ１０３に移行して、内燃機関１の１燃焼サイクルである３気筒分の吸気圧変化量ＤＰＭ２の総和、即ち、７２０〔°ＣＡ〕間の吸気圧変化量Ｄ２ＰＭ２が算出される。次にステップＳ１０４に移行して、ステップＳ１０２で算出された２４０〔°ＣＡ〕間の吸気圧変化量ＤＰＭ２とステップＳ１０３で算出された７２０〔°ＣＡ〕間の吸気圧変化量Ｄ２ＰＭ２とが比較され、最も吸気圧変化の大きい気筒が特定され、本ルーチンを終了する。
【００１９】
次に、本発明の実施の形態の第１実施例にかかる内燃機関用制御装置で使用されているＥＣＵ３０内のＣＰＵ３１における気筒間トルク変動補正・学習の処理手順を示す図３のフローチャートに基づいて説明する。なお、この気筒間トルク変動補正・学習ルーチンは４サイクル３気筒からなる内燃機関１の各気筒の燃焼間隔である２４０〔°ＣＡ〕毎にＣＰＵ３１にて繰返し実行される。
【００２０】
図３において、ステップＳ２０１では、３気筒分の吸気圧変化量ＤＰＭ２の総和である吸気圧変化量Ｄ２ＰＭ２が予め設定された所定吸気圧変化量ｋＤ２ＰＭ２未満であるかが判定される。ステップＳ２０１の判定条件が成立、即ち、吸気圧変化量Ｄ２ＰＭ２が所定吸気圧変化量ｋＤ２ＰＭ２未満と小さく、内燃機関１の１燃焼サイクルである７２０〔°ＣＡ〕間の吸気圧変動が小さいときにはステップＳ２０２に移行し、各気筒毎の吸気圧変化量ＤＰＭ２が予め設定された所定吸気圧変化量ｋＤＰＭ２を越えているかが判定される。
【００２１】
ステップＳ２０２の判定条件が成立、即ち、吸気圧変化量ＤＰＭ２が所定吸気圧変化量ｋＤＰＭ２を越え大きく、２４０〔°ＣＡ〕の燃焼間隔における吸気圧変動が大きいときにはステップＳ２０３に移行し、所定時間が経過しているかが判定される。ステップＳ２０３の判定条件が成立、即ち、ステップＳ２０１による吸気圧変化量Ｄ２ＰＭ２の状態及びステップＳ２０２による吸気圧変化量ＤＰＭ２の状態が所定時間を越え継続しているときにはステップＳ２０４に移行し、上述の図２で特定された最も吸気圧変化の大きい気筒が読込まれる。ここで、補正対象気筒としては、最も吸気圧変化で上昇している気筒または最も吸気圧変化で低下している気筒が確認される。
【００２２】
次にステップＳ２０５に移行して、最も吸気圧変化が大きな気筒に対する補正方法として点火時期の進角・遅角または燃料噴射量の増量・減量が決定される。このときの補正方法として進角または遅角が採用されるときには、最も吸気圧変化が上昇している気筒に対しては点火時期が遅角され、最も吸気圧変化が低下している気筒に対しては点火時期が進角される。ここで、進角・遅角を同時に行う必要はなく各々独立して行われる。また、このときの補正方法として増量または減量が採用されるときには、最も吸気圧変化が上昇している気筒に対しては燃料噴射量が減量され、最も吸気圧変化が低下している気筒に対しては燃料噴射量が増量される。ここで、増量・減量を同時に行う必要はなく各々独立して行われる。なお、この際、吸気圧変化量Ｄ２ＰＭ２がフィードバック（Ｆ／Ｂ）されることで補正量が変化される。
【００２３】
次にステップＳ２０６に移行して、このときの機関回転速度・負荷条件における補正気筒に対する補正量がＢ／ＵＲＡＭ３４の所定領域に格納され、この更新によって補正量が随時学習され、本ルーチンを終了する。一方、ステップＳ２０１の判定条件が成立せず、即ち、吸気圧変化量Ｄ２ＰＭ２が所定吸気圧変化量ｋＤ２ＰＭ２以上と大きく、内燃機関１の１燃焼サイクルである７２０〔°ＣＡ〕間の吸気圧変動が大きいとき、またはステップＳ２０２の判定条件が成立せず、即ち、吸気圧変化量ＤＰＭ２が所定吸気圧変化量ｋＤＰＭ２以下と小さく、２４０〔°ＣＡ〕の燃焼間隔における吸気圧変動が小さいとき、またはステップＳ２０３の判定条件が成立せず、即ち、ステップＳ２０１による吸気圧変化量Ｄ２ＰＭ２の状態及びステップＳ２０２による吸気圧変化量ＤＰＭ２の状態が所定時間未満と短いときには、何もすることなく本ルーチンを終了する。なお、本実施例によって学習された補正量は、内燃機関１の再始動後等で、同じ運転条件を満足した際に反映させることにより速やかに気筒間のトルク変動を解消することができる。
【００２４】
このように、本実施例の内燃機関用制御装置は、３気筒からなる内燃機関１の吸気通路２内のスロットルバルブ１１下流側の吸気圧ＰＭを検出する吸気圧検出手段としての吸気圧センサ２２と、内燃機関１のクランクシャフト１３の回転角を検出する回転角検出手段としてのクランク角センサ２３と、吸気圧センサ２２による吸気圧ＰＭを燃焼間隔である２４０〔°ＣＡ〕毎に平均化した各気筒の平均吸気圧ＰＭ２の吸気圧変化量ＤＰＭ２と、この吸気圧変化量ＤＰＭ２の全気筒分の総和である７２０〔°ＣＡ〕分の吸気圧変化量Ｄ２ＰＭ２とから最も変化の大きい気筒を特定するＥＣＵ３０内のＣＰＵ３１にて達成される気筒特定手段と、前記気筒特定手段で特定された気筒に対し、点火時期を進角または遅角することで気筒間のトルク変動を補正するＥＣＵ３０内のＣＰＵ３１にて達成される変動補正手段とを具備するものである。
【００２５】
つまり、吸気圧ＰＭをクランクシャフト１３の回転角に基づく燃焼間隔毎に平均化した各気筒の平均吸気圧ＰＭ２の吸気圧変化量ＤＰＭ２と、この吸気圧変化量ＤＰＭ２の全気筒分の総和である吸気圧変化量Ｄ２ＰＭ２とから最も変化の大きな気筒が特定され、この気筒に対し点火時期が進角または遅角される。この点火時期の補正により、気筒間のトルク変動を好適に解消することができる。
【００２６】
また、本実施例の内燃機関用制御装置は、３気筒からなる内燃機関１の吸気通路２内のスロットルバルブ１１下流側の吸気圧ＰＭを検出する吸気圧検出手段としての吸気圧センサ２２と、内燃機関１のクランクシャフト１３の回転角を検出する回転角検出手段としてのクランク角センサ２３と、吸気圧センサ２２による吸気圧ＰＭを燃焼間隔である２４０〔°ＣＡ〕毎に平均化した各気筒の平均吸気圧ＰＭ２の吸気圧変化量ＤＰＭ２と、この吸気圧変化量ＤＰＭ２の全気筒分の総和である７２０〔°ＣＡ〕分の吸気圧変化量Ｄ２ＰＭ２とから最も変化の大きい気筒を特定するＥＣＵ３０内のＣＰＵ３１にて達成される気筒特定手段と、前記気筒特定手段で特定された気筒に対し、燃料噴射量を増量または減量することで気筒間のトルク変動を補正するＥＣＵ３０内のＣＰＵ３１にて達成される変動補正手段とを具備するものである。
【００２７】
つまり、吸気圧ＰＭをクランクシャフト１３の回転角に基づく燃焼間隔毎に平均化した各気筒の平均吸気圧ＰＭ２の吸気圧変化量ＤＰＭ２と、この吸気圧変化量ＤＰＭ２の全気筒分の総和である吸気圧変化量Ｄ２ＰＭ２とから最も変化の大きな気筒が特定され、この気筒に対し燃料噴射量が増量または減量される。この燃料噴射量の補正により、気筒間のトルク変動を好適に解消することができる。
【００２８】
〈実施例２〉
図４は本発明の実施の形態の第２実施例にかかる内燃機関用制御装置が適用された内燃機関及びその周辺機器を示す概略構成図である。なお、図中、上述の実施例と同様の構成または相当部分からなるものについては同一符号及び同一記号を付し、その詳細な説明を省略する。
【００２９】
図４に示すように、図１の概略構成図との相違点として、内燃機関１のノック発生現象に対応したシリンダブロックの振動波形信号ＳＫＮＯＣＫ　を圧電素子（ピエゾ素子）式、電磁（マグネット、コイル）式等によって検出するノックセンサ２４が配設され、また、内燃機関１の排気通路９内の排出ガスの酸素（Ｏ_２）濃度に基づく電圧にてリニアな空燃比（Ａ／Ｆ）に対応する空燃比信号ＶＯＸ１を検出するＡ／Ｆセンサ２５が配設されている。そして、ノックセンサ２４からの振動波形信号ＳＫＮＯＣＫ　、Ａ／Ｆセンサ２５からの空燃比信号ＶＯＸ１はＥＣＵ３０に入力されている。
【００３０】
次に、本発明の実施の形態の第２実施例にかかる内燃機関用制御装置で使用されているＥＣＵ３０内のＣＰＵ３１における気筒間トルク変動補正の処理手順を示す図５のフローチャートに基づき、図６を参照して説明する。ここで、図６は図５の処理に対応する各種センサ信号や各種制御量等の遷移状態を示すタイムチャートである。この図６では、本実施例による内燃機関制御を実線にて示し、比較のために従来例による内燃機関制御を破線にて示す。なお、この気筒間トルク変動補正ルーチンは４サイクル３気筒からなる内燃機関１の各気筒の燃焼間隔である２４０〔°ＣＡ〕毎にＣＰＵ３１にて繰返し実行される。
【００３１】
図５において、ステップＳ３０１では、３気筒分の吸気圧変化量ＤＰＭ２の総和である吸気圧変化量Ｄ２ＰＭ２の絶対値（｜Ｄ２ＰＭ２｜）が予め設定された所定吸気圧変化量ｋＤ２ＰＭ２未満であるかが判定される。ステップＳ３０１の判定条件が成立、即ち、吸気圧変化量Ｄ２ＰＭ２の絶対値が所定吸気圧変化量ｋＤ２ＰＭ２未満と小さく、内燃機関１の１燃焼サイクルである７２０〔°ＣＡ〕間の吸気圧変動が小さいときにはステップＳ３０２に移行し、最も吸気圧が低下または上昇している気筒の特定が、図６に判定期間として示す時刻ｔ０４〜時刻ｔ０７の間に実行される。
【００３２】
次にステップＳ３０３に移行して、３気筒分の吸気圧変化量ＤＰＭ２の総和である吸気圧変化量Ｄ２ＰＭ２のＭＡＸ（最大）値からＭＩＮ（最小）値が減算され、図６に示す吸気圧変化量振幅Ｄ２ＰＭ２Ａが算出される。
【００３３】
次にステップＳ３０４に移行して、吸気圧変化量振幅Ｄ２ＰＭ２Ａが予め設定された所定吸気圧変化量振幅ｋＤ２ＰＭ２Ａを越えているかが判定される。ステップＳ３０４の判定条件が成立、即ち、吸気圧変化量振幅Ｄ２ＰＭ２Ａが所定吸気圧変化量振幅ｋＤ２ＰＭ２Ａを越え大きく、７２０〔°ＣＡ〕間の吸気圧変化量振幅変動が大きいとき（図６に示す時刻ｔ０４以降）にはステップＳ３０５に移行し、所定時間（図６の時刻ｔ０４〜時刻ｔ０７に示す判定期間）が経過しているかが判定される。ステップＳ３０５の判定条件が成立、即ち、吸気圧変化量振幅Ｄ２ＰＭ２Ａ変動が大きく所定時間を越え継続しているときにはステップＳ３０６に移行し、ノックが有るかが判定される。
【００３４】
ステップＳ３０６の判定条件が成立、即ち、ノックセンサ２４からの振動波形信号ＳＫＮＯＣＫ　に基づき周知のようにノック有りと判定されたときにはステップＳ３０７に移行し、内燃機関１の３気筒のうち最も吸気圧が上昇している気筒に対する点火時期の遅角が実行され、本ルーチンを終了する。一方、ステップＳ３０６の判定条件が成立せず、即ち、ノックセンサ２４からの振動波形信号ＳＫＮＯＣＫ　に基づき周知のようにノックなしと判定されたときにはステップＳ３０８に移行し、内燃機関１の３気筒のうち最も吸気圧が低下している＃３気筒に対する点火時期の進角が実行され（図６に示す時刻ｔ０８、時刻ｔ１０、時刻ｔ１２、時刻ｔ１４）、本ルーチンを終了する。
【００３５】
これにより、図６に破線にて示す従来例の制御では、吸気圧ＰＭ及び吸気圧変化量ＤＰＭ２の大きな変動、また、吸気圧変化量振幅Ｄ２ＰＭ２Ａの発散が起こるが、図６に実線にて示す本実施例の制御によれば、気筒間の吸気圧変動が大きくなる以前に、内燃機関１の３気筒（＃１気筒〜＃３気筒）のうちの＃３気筒に対して点火時期の進角処理が実行されることで吸気圧ＰＭ及び吸気圧変化量ＤＰＭ２の変動、かつ吸気圧変化量振幅Ｄ２ＰＭ２Ａの発散を未然に防止することができ、気筒間のトルク変動が好適に補正される。
【００３６】
一方、ステップＳ３０１の判定条件が成立せず、即ち、吸気圧変化量Ｄ２ＰＭ２の絶対値が所定吸気圧変化量ｋＤ２ＰＭ２以上と大きいとき、またはステップＳ３０４の判定条件が成立せず、即ち、吸気圧変化量振幅Ｄ２ＰＭ２Ａが所定吸気圧変化量振幅ｋＤ２ＰＭ２Ａ以下と小さく、７２０〔°ＣＡ〕間の吸気圧変化量振幅変動が小さいとき、またはステップＳ３０５の判定条件が成立せず、即ち、ステップＳ３０３による吸気圧変化量振幅Ｄ２ＰＭ２Ａが所定吸気圧変化量振幅ｋＤ２ＰＭ２Ａを越え大きな状態が所定時間未満と短いときには、何もすることなく本ルーチンを終了する。なお、学習制御として、このときの運転条件に対応する点火時期の補正量をＢ／ＵＲＡＭ３４に格納し、内燃機関１の再始動後等で、同じ運転条件を満足した際に反映させることにより速やかに気筒間のトルク変動を解消することができる。
【００３７】
このように、本実施例の内燃機関用制御装置は、３気筒からなる内燃機関１の吸気通路２内のスロットルバルブ１１下流側の吸気圧ＰＭを検出する吸気圧検出手段としての吸気圧センサ２２と、内燃機関１のクランクシャフト１３の回転角を検出する回転角検出手段としてのクランク角センサ２３と、内燃機関１で発生する振動波形信号ＳＫＮＯＣＫ　を検出する振動検出手段としてのノックセンサ２４と、ノックセンサ２４による振動波形信号ＳＫＮＯＣＫ　に基づきノック発生の有無を判定するＥＣＵ３０内のＣＰＵ３１にて達成されるノック判定手段と、吸気圧センサ２２による吸気圧ＰＭを燃焼間隔である２４０〔°ＣＡ〕毎に平均化した各気筒の平均吸気圧ＰＭ２の吸気圧変化量ＤＰＭ２と、この吸気圧変化量ＤＰＭ２の全気筒分の総和である７２０〔°ＣＡ〕分の吸気圧変化量Ｄ２ＰＭ２とから最も変化の大きい気筒を特定するＥＣＵ３０内のＣＰＵ３１にて達成される気筒特定手段と、前記ノック判定手段による判定結果に基づき、前記気筒特定手段で特定された気筒に対し、点火時期を進角または遅角することで気筒間のトルク変動を補正するＥＣＵ３０内のＣＰＵ３１にて達成される変動補正手段とを具備するものである。
【００３８】
つまり、吸気圧ＰＭをクランクシャフト１３の回転角に基づく燃焼間隔毎に平均化した各気筒の平均吸気圧ＰＭ２の吸気圧変化量ＤＰＭ２と、この吸気圧変化量ＤＰＭ２の全気筒分の総和である吸気圧変化量Ｄ２ＰＭ２とから最も変化の大きな気筒が特定され、更に、ノックセンサ２４からの振動波形信号ＳＫＮＯＣＫ　による判定結果に基づき、特定された気筒に対し点火時期が進角または遅角される。この点火時期の補正により、気筒間のトルク変動を好適に解消することができる。
【００３９】
なお、上記実施例では、内燃機関１のノックを検出するノックセンサ２４を用いたノック検出結果に基づき点火時期を進角または遅角することで気筒間のトルク変動をなくしているが本発明を実施する場合には、これに限定されるものではなく、内燃機関１の排気通路９内における排出ガスの空燃比を検出可能なＡ／Ｆセンサ２５からの空燃比信号ＶＯＸ１を用いた空燃比検出結果に基づき燃料噴射量を増量または減量することで気筒間のトルク変動をなくすこともできる。また、このＡ／Ｆセンサ２５に替えて空燃比のリッチまたはリーンを検出可能な酸素センサを用いることもできる。
【００４０】
このような内燃機関用制御装置は、３気筒からなる内燃機関１の吸気通路２内のスロットルバルブ１１下流側の吸気圧ＰＭを検出する吸気圧検出手段としての吸気圧センサ２２と、内燃機関１のクランクシャフト１３の回転角を検出する回転角検出手段としてのクランク角センサ２３と、内燃機関１の排気通路９内における排出ガスの空燃比（Ａ／Ｆ）に対応する空燃比信号ＶＯＸ１を検出する空燃比検出手段としてのＡ／Ｆセンサ２５と、吸気圧センサ２２による吸気圧ＰＭを燃焼間隔である２４０〔°ＣＡ〕毎に平均化した各気筒の平均吸気圧ＰＭ２の吸気圧変化量ＤＰＭ２と、この吸気圧変化量ＤＰＭ２の全気筒分の総和である７２０〔°ＣＡ〕分の吸気圧変化量Ｄ２ＰＭ２とから最も変化の大きい気筒を特定するＥＣＵ３０内のＣＰＵ３１にて達成される気筒特定手段と、吸気圧センサ２２による検出結果に基づき、前記気筒特定手段で特定された気筒に対し、燃料噴射量を増量または減量することで気筒間のトルク変動を補正するＥＣＵ３０内のＣＰＵ３１にて達成される変動補正手段とを具備するものであり、上述の実施例と同様の作用・効果が期待できる。
【００４１】
ところで、上記実施例では、４サイクル３気筒からなる内燃機関について述べたが、本発明を実施する場合には、これに限定されるものではなく、その他、複数気筒からなる内燃機関に適用することで、同様の効果を得ることができる。
【００４２】
また、上記実施例では、内燃機関１のクランクシャフト１３の回転角を検出する回転角検出手段としてクランク角センサ２３を用いているが、本発明を実施する場合には、これに限定されるものではなく、吸気バルブ６または排気バルブ８を開閉駆動させるための図示しないカムシャフトの回転角を検出するカム角センサからの信号を用いることもできる。
【００４３】
なお、上記実施例では、吸気通路内の吸気圧を検出して燃料噴射量を設定する、所謂Ｄ−Ｊシステムへの適用について述べたが、本発明を実施する場合には、これに限定されるものではなく、更に、Ｄ−Ｊシステムで、特に、排気タービン過給機（Ｔｕｒｂｏｃｈａｒｇｅｒ；以下、単に『Ｔ／Ｃ』と記す）を備えた内燃機関への適用が有効である。即ち、Ｄ−Ｊシステムで、Ｔ／Ｃを備えた内燃機関にあっては、特に、運転条件の変化が少ない状態であっても気筒間のトルク差が広がり、Ｔ／Ｃ過給領域で吸気脈動が拡大する傾向にある。このような現象があるものにおいては、運転条件の変化が少ない状態であっても吸気脈動によって誤って加速判定される可能性がある。この加速判定によって燃料増減量が設定されると、結果として、機関回転速度の変動が発生することとなるが、本発明にかかる内燃機関用制御装置が適用された内燃機関においては、各気筒の吸気圧変化量に基づき点火時期や燃料噴射量が適切に補正されることで気筒間のトルク変動が解消されるという効果が期待できる。
【図面の簡単な説明】
【図１】図１は本発明の実施の形態の第１実施例にかかる内燃機関用制御装置が適用された内燃機関及びその周辺機器を示す概略構成図である。
【図２】図２は本発明の実施の形態の第１実施例にかかる内燃機関用制御装置で使用されているＥＣＵ内のＣＰＵにおける気筒特定の処理手順を示すフローチャートである。
【図３】図３は本発明の実施の形態の第１実施例にかかる内燃機関用制御装置で使用されているＥＣＵ内のＣＰＵにおける気筒間トルク変動補正・学習の処理手順を示すフローチャートである。
【図４】図４は本発明の実施の形態の第２実施例にかかる内燃機関用制御装置が適用された内燃機関及びその周辺機器を示す概略構成図である。
【図５】図５は本発明の実施の形態の第２実施例にかかる内燃機関用制御装置で使用されているＥＣＵ内のＣＰＵにおける気筒間トルク変動補正の処理手順を示すフローチャートである。
【図６】図６は図５の処理に対応する各種センサ信号や各種制御量等の遷移状態を示すタイムチャートである。
【符号の説明】
１　内燃機関
２　吸気通路
５　インジェクタ（燃料噴射弁）
１１　スロットルバルブ
２１　スロットル開度センサ
２２　吸気圧センサ
２３　クランク角センサ
２４　ノックセンサ
２５　Ａ／Ｆセンサ
３０　ＥＣＵ（電子制御ユニット）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for an internal combustion engine that eliminates torque fluctuation between cylinders by correcting an ignition timing and a fuel injection amount of the internal combustion engine.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a prior art document related to a control device for an internal combustion engine, one disclosed in Japanese Patent Publication No. 8-33117 is known. In this method, a fuel injection amount is calculated from a transient correction fuel increase corresponding to a transient state such as an acceleration state based on a change amount of an average value of intake pressure data and a basic fuel amount based on a crank angle signal and an average value of intake pressure data. Is shown.
[0003]
[Problems to be solved by the invention]
By the way, in the foregoing, a dead zone is provided for the amount of change in the average value of the intake pressure data, and improper addition of the corrected fuel increase to the basic fuel amount during transition is prohibited. Here, a system for injecting fuel for all cylinders at the same time (720 [° CA (Crank Angle: crank angle)]) has been described. However, at present, fuel injection is performed for each cylinder (every 240 [° CA] for three cylinders). Independent fuel injection systems have become common. For example, when the driver (driver) depresses the accelerator pedal and the amount of change in the intake pressure data exceeds the dead zone, the acceleration is increased. Thereafter, when the driver keeps the accelerator opening when the accelerator pedal is depressed and keeps accelerating and gradually increasing the rotation, the intake pulsation expands due to the intake inertia effect in a specific rotation speed range.
[0004]
In a system in which the fuel injection amount is calculated for each cylinder (every 240 [° CA] in the case of three cylinders) and the fuel is independently injected, the amount of change in the intake pressure data exceeds the dead zone due to the expansion of the intake pulsation described above. For cylinders with large intake pulsations, the pressure change for each combustion is captured and the amount is increased or decreased.Therefore, the specific cylinder is increased or decreased, and the increased cylinder and the decreased cylinder are used. There was a problem that the torque difference increased and drivability deteriorated.
[0005]
Therefore, the present invention has been made to solve such a problem, and it is possible to eliminate the torque fluctuation between cylinders by appropriately correcting the ignition timing and the fuel injection amount based on the intake pressure change amount of each cylinder of the internal combustion engine. It is an object to provide a control device for an internal combustion engine.
[0006]
[Means for Solving the Problems]
According to the control device for an internal combustion engine of the first aspect, the rotational pressure detecting means detects the intake pressure on the downstream side of the throttle valve in the intake passage of the internal combustion engine composed of a plurality of cylinders detected by the cylinder identifying means by the intake pressure detecting means. The intake pressure change amount of the average intake pressure of each cylinder averaged for each combustion interval based on the detected crankshaft or camshaft rotation angle, and the intake pressure change amount that is the sum of the intake pressure change amount for all cylinders Thus, the cylinder with the largest change is specified, and the ignition timing is advanced or retarded by the fluctuation correction means for this cylinder. This correction of the ignition timing has an effect that torque fluctuation between cylinders is suitably eliminated.
[0007]
According to the control device for an internal combustion engine of the second aspect, the intake pressure on the downstream side of the throttle valve in the intake passage of the internal combustion engine consisting of a plurality of cylinders detected by the cylinder identification means by the intake pressure detection means is detected by the rotation angle detection means. The intake pressure change amount of the average intake pressure of each cylinder averaged for each combustion interval based on the detected crankshaft or camshaft rotation angle, and the intake pressure change amount that is the sum of the intake pressure change amount for all cylinders Thus, the cylinder with the largest change is specified, and the fuel injection amount is increased or decreased for this cylinder by the fluctuation correction means. By this correction of the fuel injection amount, an effect is obtained that torque fluctuation between cylinders is suitably eliminated.
[0008]
According to the control device for an internal combustion engine of the third aspect, the rotational pressure detecting means detects the intake pressure on the downstream side of the throttle valve in the intake passage of the internal combustion engine composed of a plurality of cylinders detected by the cylinder identifying means by the intake pressure detecting means. The intake pressure change amount of the average intake pressure of each cylinder averaged for each combustion interval based on the detected crankshaft or camshaft rotation angle, and the intake pressure change amount that is the sum of the intake pressure change amount for all cylinders The cylinder with the largest change is specified from the above, and further, the ignition timing is advanced or retarded with respect to the specified cylinder based on the determination result of the presence or absence of knock by the knock determination unit based on the vibration waveform signal by the vibration detection unit. Is done. This correction of the ignition timing has an effect that torque fluctuation between cylinders is suitably eliminated.
[0009]
According to the internal combustion engine control device of the fourth aspect, the intake pressure on the downstream side of the throttle valve in the intake passage of the internal combustion engine composed of a plurality of cylinders detected by the cylinder pressure identifying unit by the intake pressure detecting unit is detected by the rotation angle detecting unit. The intake pressure change amount of the average intake pressure of each cylinder averaged for each combustion interval based on the detected crankshaft or camshaft rotation angle, and the intake pressure change amount that is the sum of the intake pressure change amount for all cylinders And the cylinder with the largest change is specified, and the fuel injection amount is increased or decreased with respect to the specified cylinder based on the detection result of the air-fuel ratio of the exhaust gas in the exhaust passage of the internal combustion engine by the air-fuel ratio detection means. You. By this correction of the fuel injection amount, an effect is obtained that torque fluctuation between cylinders is suitably eliminated.
[0010]
In the control device for an internal combustion engine according to the fifth aspect, the internal combustion engine includes an exhaust turbine supercharger, rotates the turbine by using exhaust pressure, and sends a large amount of intake air to the combustion chamber by rotating the turbine. Applies to the system. The phenomenon that the intake pulsation increases when the driver depresses the accelerator pedal and thereafter holds the depression amount of the accelerator pedal is particularly noticeable in a system having an exhaust turbine supercharger. In a system including an exhaust turbine supercharger, a turbine is rotated using exhaust pressure, and a large amount of intake air is sent to a combustion chamber by rotating the turbine. That is, when the driver depresses the accelerator pedal and thereafter holds the accelerator pedal depression amount, even if the increase in the engine speed is small, the rotation of the turbine increases and the intake air amount increases due to the supercharging effect. As a result, there is a phenomenon in which the engine rotation speed and the turbine rotation interfere with each other and synchronize with the fluctuation frequency of each cylinder to generate a large fluctuation as intake pulsation. Therefore, a great effect can be expected when applied to a system in which an internal combustion engine is provided with an exhaust turbine supercharger.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples.
[0012]
<Example 1>
FIG. 1 is a schematic configuration diagram showing an internal combustion engine to which an internal combustion engine control device according to a first example of the embodiment of the present invention is applied and peripheral devices thereof.
[0013]
In FIG. 1, reference numeral 1 denotes an internal combustion engine including a plurality of cylinders, for example, a four-cycle, three-cylinder engine. A throttle valve 11 which is opened and closed in response to an operation of an accelerator pedal or the like (not shown) is arranged in the middle of the intake passage 2 as requested by a driver (driver). By opening and closing the throttle valve 11, the amount of intake air to the intake passage 2 is adjusted. Simultaneously with this intake air amount, a fuel pressure-fed from a fuel tank (not shown) by a fuel pump and regulated through a pressure regulator is supplied to an injector disposed in the intake passage 2 near the intake port 4 of the internal combustion engine 1. (Fuel injection valve) 5 is supplied by injection. Then, an air-fuel mixture consisting of a predetermined fuel amount and an intake amount is sucked into the combustion chamber 7 via the intake valve 6.
[0014]
The throttle valve 11 in the middle of the intake passage 2 is provided with a throttle opening sensor 21 for detecting a throttle opening THR according to an accelerator pedal depression amount or the like. An intake pressure sensor 22 that detects an intake pressure PM in the intake passage 2 is provided downstream of the throttle valve 11. The crankshaft 13 of the internal combustion engine 1 is provided with a crank angle sensor 23 for detecting a crank angle [° CA (Crack Angle)] accompanying the rotation. The engine speed NE of the internal combustion engine 1 is calculated based on the crank angle detected by the crank angle sensor 23.
[0015]
Further, an ignition plug 14 is provided toward the inside of the combustion chamber 7 of the internal combustion engine 1. The ignition plug 14 receives a signal from the ignition coil / igniter 15 based on an ignition command signal output from an ECU (Electronic Control Unit) 30 described later in synchronization with the crank angle detected by the crank angle sensor 23. A voltage is applied, and ignition combustion of the air-fuel mixture in the combustion chamber 7 is performed. In this way, the air-fuel mixture in the combustion chamber 7 is burned (expanded) to obtain a driving force, and the exhaust gas after the combustion is led out of the exhaust manifold 9 through the exhaust valve 8 to the exhaust passage 9 and discharged to the outside. You.
[0016]
The ECU 30 includes a CPU 31 as a central processing unit for executing various known arithmetic processing, a ROM 32 for storing a control program, a RAM 33 for storing various data, a B / U (backup) RAM 34, an input / output circuit 35, and a bus connecting them. It is configured as a logical operation circuit including the line 36 and the like. The ECU 30 receives the throttle opening THR from the throttle opening sensor 21, the intake pressure PM from the intake pressure sensor 22, the rotation angle of the crankshaft 13 from the crank angle sensor 23, the engine speed NE, and the like. . Based on output signals from the ECU 30 based on these various types of sensor information, the injector 5 related to the fuel injection timing and fuel injection amount, the spark plug 14 related to the ignition timing, the ignition coil / igniter 15, and the like are appropriately controlled.
[0017]
Next, a description will be given based on a flowchart of FIG. 2 showing a cylinder identification processing procedure in the CPU 31 in the ECU 30 used in the internal combustion engine control device according to the first example of the embodiment of the present invention. Note that this cylinder specifying routine is repeatedly executed by the CPU 31 every 240 [° CA], which is the combustion (ignition) interval of each cylinder of the internal combustion engine 1 composed of three cylinders of four cycles.
[0018]
In FIG. 2, in step S101, an average intake pressure PM2 for 240 [° CA] obtained by averaging the intake pressure PM from the intake pressure sensor 22 for each combustion interval is calculated. Next, the process proceeds to step S102, and the intake pressure change amount DPM2 between 240 [° CA] which is the difference between the previous value and the current value of the average intake pressure PM2 calculated in step S101 is calculated. Next, the routine proceeds to step S103, where the sum of the intake pressure change amounts DPM2 for three cylinders, which is one combustion cycle of the internal combustion engine 1, that is, the intake pressure change amount D2PM2 for 720 [° CA] is calculated. Next, the process proceeds to step S104, where the intake pressure change amount DPM2 between 240 [° CA] calculated in step S102 and the intake pressure change amount D2PM2 between 720 [° CA] calculated in step S103 are compared. Then, the cylinder having the largest change in intake pressure is specified, and this routine ends.
[0019]
Next, based on a flowchart of FIG. 3 showing a processing procedure of inter-cylinder torque fluctuation correction / learning in the CPU 31 in the ECU 30 used in the internal combustion engine control device according to the first example of the embodiment of the present invention. explain. Note that this inter-cylinder torque fluctuation correction / learning routine is repeatedly executed by the CPU 31 every 240 [° CA], which is the combustion interval of each cylinder of the internal combustion engine 1 composed of four cylinders and three cylinders.
[0020]
In FIG. 3, in step S201, it is determined whether the intake pressure change amount D2PM2, which is the sum of the intake pressure change amounts DPM2 for the three cylinders, is less than a predetermined intake pressure change amount kD2PM2 set in advance. If the determination condition of step S201 is satisfied, that is, if the intake pressure change amount D2PM2 is smaller than the predetermined intake pressure change amount kD2PM2 and the intake pressure change during 720 [° CA], which is one combustion cycle of the internal combustion engine 1, is small, step S202 is performed. Then, it is determined whether the intake pressure change amount DPM2 for each cylinder exceeds a predetermined intake pressure change amount kDPM2.
[0021]
When the determination condition of step S202 is satisfied, that is, when the intake pressure change amount DPM2 exceeds the predetermined intake pressure change amount kDPM2 and is large and the intake pressure change in the combustion interval of 240 [° CA] is large, the process proceeds to step S203 and the predetermined time It is determined whether it has passed. When the determination condition of step S203 is satisfied, that is, when the state of the intake pressure change amount D2PM2 in step S201 and the state of the intake pressure change amount DPM2 in step S202 continue for more than a predetermined time, the process proceeds to step S204, and the above-described process is performed. The cylinder with the largest change in intake pressure specified in 2 is read. Here, as the cylinder to be corrected, a cylinder that is rising due to a change in intake pressure or a cylinder that is decreasing due to a change in intake pressure is confirmed.
[0022]
Next, the process proceeds to step S205, in which advance or retard of the ignition timing or increase or decrease of the fuel injection amount is determined as a correction method for the cylinder having the largest change in the intake pressure. When advancing or retarding is adopted as the correction method at this time, the ignition timing is retarded for the cylinder with the highest intake pressure change, and the ignition timing is retarded for the cylinder with the lowest intake pressure change. In this case, the ignition timing is advanced. Here, the advance angle and the retard angle need not be performed simultaneously, but are performed independently. When the increase or decrease is adopted as the correction method at this time, the fuel injection amount is reduced for the cylinder with the highest intake pressure change, and is reduced for the cylinder with the lowest intake pressure change. Therefore, the fuel injection amount is increased. Here, it is not necessary to increase and decrease the amounts at the same time, and they are performed independently. At this time, the correction amount is changed by feedback (F / B) of the intake pressure change amount D2PM2.
[0023]
Next, the routine proceeds to step S206, where the correction amount for the correction cylinder under the engine speed / load condition at this time is stored in a predetermined area of the B / URAM 34, the correction amount is learned as needed by this update, and this routine ends. . On the other hand, the determination condition of step S201 is not satisfied, that is, the intake pressure change amount D2PM2 is as large as the predetermined intake pressure change amount kD2PM2 or more, and the intake pressure change during 720 [° CA] which is one combustion cycle of the internal combustion engine 1 When it is large, or when the determination condition of step S202 is not satisfied, that is, when the intake pressure change amount DPM2 is as small as not more than the predetermined intake pressure change amount kDPM2 and the intake pressure fluctuation in the combustion interval of 240 [° CA] is small, or When the determination condition of S203 is not satisfied, that is, when the state of the intake pressure change amount D2PM2 in step S201 and the state of the intake pressure change amount DPM2 in step S202 are shorter than the predetermined time, this routine is terminated without any operation. . It should be noted that the correction amount learned according to the present embodiment is reflected when the same operating conditions are satisfied, for example, after the internal combustion engine 1 is restarted, so that the torque fluctuation between the cylinders can be quickly eliminated.
[0024]
As described above, the control device for an internal combustion engine according to the present embodiment includes the intake pressure sensor 22 as intake pressure detection means for detecting the intake pressure PM downstream of the throttle valve 11 in the intake passage 2 of the internal combustion engine 1 having three cylinders. And a crank angle sensor 23 as a rotation angle detecting means for detecting a rotation angle of the crankshaft 13 of the internal combustion engine 1 and an intake pressure PM by the intake pressure sensor 22 are averaged at every 240 [° CA] which is a combustion interval. The cylinder with the largest change is specified from the intake pressure change amount DPM2 of the average intake pressure PM2 of each cylinder and the intake pressure change amount D2PM2 of 720 [° CA] which is the sum of all the intake pressure change amounts DPM2 for all the cylinders. The torque variation between the cylinders is achieved by advancing or retarding the ignition timing with respect to the cylinder specifying means achieved by the CPU 31 in the ECU 30 and the cylinder specified by the cylinder specifying means. And a fluctuation correction means achieved by the CPU 31 in the ECU 30 that corrects the fluctuation.
[0025]
That is, it is the sum of the intake pressure change DPM2 of the average intake pressure PM2 of each cylinder obtained by averaging the intake pressure PM for each combustion interval based on the rotation angle of the crankshaft 13, and the sum of the intake pressure change DPM2 for all cylinders. The cylinder with the largest change is specified from the intake pressure change amount D2PM2, and the ignition timing is advanced or retarded for this cylinder. By this correction of the ignition timing, torque fluctuation between cylinders can be suitably eliminated.
[0026]
Further, the control device for an internal combustion engine of the present embodiment includes an intake pressure sensor 22 as intake pressure detection means for detecting an intake pressure PM downstream of the throttle valve 11 in the intake passage 2 of the internal combustion engine 1 having three cylinders; Crank angle sensor 23 as a rotation angle detecting means for detecting the rotation angle of crankshaft 13 of internal combustion engine 1, and each cylinder obtained by averaging intake pressure PM by intake pressure sensor 22 for every 240 [° CA] which is a combustion interval ECU 30 that specifies the cylinder with the largest change from intake pressure change amount DPM2 of average intake pressure PM2 and intake pressure change amount D2PM2 of 720 [° CA] that is the sum of all intake pressure change amounts DPM2 for all cylinders. The torque variation between the cylinders is compensated by increasing or decreasing the fuel injection amount with respect to the cylinder specifying means achieved by the CPU 31 and the cylinder specified by the cylinder specifying means. And a fluctuation correction means achieved by the CPU 31 in the ECU 30.
[0027]
That is, it is the sum of the intake pressure change DPM2 of the average intake pressure PM2 of each cylinder obtained by averaging the intake pressure PM for each combustion interval based on the rotation angle of the crankshaft 13, and the sum of the intake pressure change DPM2 for all cylinders. The cylinder having the largest change is specified from the intake pressure change amount D2PM2, and the fuel injection amount is increased or decreased for this cylinder. By this correction of the fuel injection amount, torque fluctuation between cylinders can be suitably eliminated.
[0028]
<Example 2>
FIG. 4 is a schematic configuration diagram showing an internal combustion engine to which the control device for an internal combustion engine according to the second example of the embodiment of the present invention is applied and peripheral devices thereof. In the drawing, the same reference numerals and symbols are given to components having the same configuration or corresponding portions as those in the above-described embodiment, and detailed description thereof will be omitted.
[0029]
As shown in FIG. 4, the difference from the schematic configuration diagram of FIG. 1 is that the vibration waveform signal SKNOCK of the cylinder block corresponding to the knock generation phenomenon of the internal combustion engine 1 is obtained by a piezoelectric element (piezo element) type, electromagnetic (magnet, coil) ) Is provided, and the knock sensor 24 for detecting the exhaust gas in the exhaust passage 9 of the internal combustion engine 1 is provided. ₂ An A / F sensor 25 for detecting an air-fuel ratio signal VOX1 corresponding to a linear air-fuel ratio (A / F) with a voltage based on the concentration is provided. The vibration waveform signal SKNOCK from the knock sensor 24 and the air-fuel ratio signal VOX1 from the A / F sensor 25 are input to the ECU 30.
[0030]
Next, based on the flowchart of FIG. 5 showing the processing procedure of the inter-cylinder torque fluctuation correction by the CPU 31 in the ECU 30 used in the internal combustion engine control device according to the second example of the embodiment of the present invention, FIG. This will be described with reference to FIG. Here, FIG. 6 is a time chart showing transition states of various sensor signals and various control amounts corresponding to the processing of FIG. In FIG. 6, the internal combustion engine control according to the present embodiment is indicated by a solid line, and the internal combustion engine control according to the conventional example is indicated by a broken line for comparison. The inter-cylinder torque fluctuation correction routine is repeatedly executed by the CPU 31 at every 240 [° CA], which is the combustion interval of each cylinder of the internal combustion engine 1 having four cylinders and three cylinders.
[0031]
In FIG. 5, in step S301, it is determined whether the absolute value (| D2PM2 |) of the intake pressure change amount D2PM2, which is the sum of the intake pressure change amounts DPM2 for the three cylinders, is less than a predetermined intake pressure change amount kD2PM2 set in advance. Is determined. The determination condition of step S301 is satisfied, that is, the absolute value of the intake pressure change amount D2PM2 is smaller than the predetermined intake pressure change amount kD2PM2, and the intake pressure fluctuation during 720 [° CA], which is one combustion cycle of the internal combustion engine 1, is small. Sometimes, the process proceeds to step S302, and the cylinder whose intake pressure is the lowest or the highest is specified between time t04 and time t07 shown as the determination period in FIG.
[0032]
Next, in step S303, the MIN (minimum) value is subtracted from the MAX (maximum) value of the intake pressure change amount D2PM2, which is the sum of the intake pressure change amounts DPM2 for the three cylinders, and the intake pressure change shown in FIG. The quantity amplitude D2PM2A is calculated.
[0033]
Next, the process proceeds to step S304, and it is determined whether the intake pressure change amount amplitude D2PM2A exceeds a predetermined intake pressure change amount amplitude kD2PM2A. When the determination condition of step S304 is satisfied, that is, when the intake pressure change amount amplitude D2PM2A exceeds the predetermined intake pressure change amount amplitude kD2PM2A and is large, and the intake pressure change amount amplitude fluctuation during 720 [° CA] is large (time shown in FIG. 6). After t04), the process proceeds to step S305, and it is determined whether a predetermined time (a determination period from time t04 to time t07 in FIG. 6) has elapsed. When the determination condition of step S305 is satisfied, that is, when the variation in the intake pressure change amount amplitude D2PM2A is large and continues beyond the predetermined time, the process proceeds to step S306, and it is determined whether knock is present.
[0034]
When the determination condition of step S306 is satisfied, that is, when it is determined that knock is present as is well known based on the vibration waveform signal SKNOCK from the knock sensor 24, the process proceeds to step S307, and the intake pressure becomes the highest among the three cylinders of the internal combustion engine 1. The ignition timing of the rising cylinder is retarded, and the routine ends. On the other hand, when the determination condition of step S306 is not satisfied, that is, when it is determined that there is no knock as is well known based on the vibration waveform signal SKNOCK from the knock sensor 24, the process proceeds to step S308, and among the three cylinders of the internal combustion engine 1, The ignition timing is advanced for the # 3 cylinder with the lowest intake pressure (time t08, time t10, time t12, time t14 shown in FIG. 6), and this routine ends.
[0035]
Thereby, in the control of the conventional example shown by the broken line in FIG. 6, a large fluctuation of the intake pressure PM and the intake pressure change amount DPM2 and the divergence of the intake pressure change amount amplitude D2PM2A occur. According to the control of the present embodiment, the advance of the ignition timing with respect to the # 3 cylinder among the three cylinders (# 1 cylinder to # 3 cylinder) of the internal combustion engine 1 before the fluctuation of the intake pressure between the cylinders becomes large. By executing the processing, the fluctuation of the intake pressure PM and the intake pressure change amount DPM2 and the divergence of the intake pressure change amount amplitude D2PM2A can be prevented beforehand, and the torque fluctuation between the cylinders is appropriately corrected.
[0036]
On the other hand, when the determination condition of step S301 is not satisfied, that is, when the absolute value of the intake pressure change amount D2PM2 is greater than or equal to the predetermined intake pressure change amount kD2PM2, or when the determination condition of step S304 is not satisfied, that is, when the intake pressure change When the amount amplitude D2PM2A is as small as or less than the predetermined intake pressure change amount amplitude kD2PM2A and the change in intake pressure change amount during 720 [° CA] is small, or the determination condition of step S305 is not satisfied, that is, the intake pressure in step S303. When the change amount amplitude D2PM2A exceeds the predetermined intake pressure change amount amplitude kD2PM2A and the large state is shorter than the predetermined time, the routine ends without any operation. As the learning control, the correction amount of the ignition timing corresponding to the operating condition at this time is stored in the B / URAM 34, and is reflected when the same operating condition is satisfied, for example, after the internal combustion engine 1 is restarted. Thus, torque fluctuation between cylinders can be eliminated.
[0037]
As described above, the control device for an internal combustion engine according to the present embodiment includes the intake pressure sensor 22 as intake pressure detection means for detecting the intake pressure PM downstream of the throttle valve 11 in the intake passage 2 of the internal combustion engine 1 having three cylinders. A crank angle sensor 23 as a rotation angle detecting means for detecting a rotation angle of the crankshaft 13 of the internal combustion engine 1, a knock sensor 24 as a vibration detecting means for detecting a vibration waveform signal SKNOCK generated in the internal combustion engine 1, Knock determination means achieved by CPU 31 in ECU 30 which determines whether knock has occurred based on vibration waveform signal SKNOCK from knock sensor 24, and intake pressure PM detected by intake pressure sensor 22 at every 240 [° CA] combustion interval. Pressure change amount DPM2 of the average intake pressure PM2 of each cylinder averaged in Based on the cylinder identification means achieved by the CPU 31 in the ECU 30 for identifying the cylinder with the largest change from the intake pressure change amount D2PM2 for 720 [° CA] which is the sum, and the determination result by the knock determination means, A variation correction means is provided by a CPU 31 in the ECU 30 for correcting the torque variation between the cylinders by advancing or retarding the ignition timing with respect to the cylinder specified by the cylinder specifying means.
[0038]
That is, it is the sum of the intake pressure change DPM2 of the average intake pressure PM2 of each cylinder obtained by averaging the intake pressure PM for each combustion interval based on the rotation angle of the crankshaft 13, and the sum of the intake pressure change DPM2 for all cylinders. The cylinder with the largest change is specified from the intake pressure change amount D2PM2, and the ignition timing is advanced or retarded with respect to the specified cylinder based on the determination result based on the vibration waveform signal SKNOCK from the knock sensor 24. By this correction of the ignition timing, torque fluctuation between cylinders can be suitably eliminated.
[0039]
In the above embodiment, the ignition timing is advanced or retarded based on the knock detection result using the knock sensor 24 that detects the knock of the internal combustion engine 1 to eliminate the torque fluctuation between the cylinders. The present invention is not limited to this. The air-fuel ratio detection using the air-fuel ratio signal VOX1 from the A / F sensor 25 capable of detecting the air-fuel ratio of the exhaust gas in the exhaust passage 9 of the internal combustion engine 1 By increasing or decreasing the fuel injection amount based on the result, torque fluctuation between cylinders can be eliminated. Further, instead of the A / F sensor 25, an oxygen sensor capable of detecting rich or lean air-fuel ratio can be used.
[0040]
Such an internal combustion engine control device includes an intake pressure sensor 22 as intake pressure detection means for detecting an intake pressure PM downstream of a throttle valve 11 in an intake passage 2 of an internal combustion engine 1 having three cylinders, and an internal combustion engine 1. And an air-fuel ratio signal VOX1 corresponding to the air-fuel ratio (A / F) of the exhaust gas in the exhaust passage 9 of the internal combustion engine 1. A / F sensor 25 as an air-fuel ratio detecting means, and an intake pressure change amount DPM2 of an average intake pressure PM2 of each cylinder obtained by averaging the intake pressure PM by the intake pressure sensor 22 for every 240 [° CA] which is a combustion interval. The CPU in the ECU 30 for specifying the cylinder having the largest change from the intake pressure change amount D2PM2 for 720 [° CA] which is the sum of all the intake pressure change amounts DPM2 for all cylinders. The torque variation between the cylinders is corrected by increasing or decreasing the fuel injection amount for the cylinder specified by the cylinder specifying means based on the cylinder specifying means achieved at 31 and the detection result by the intake pressure sensor 22. And a variation correction means achieved by the CPU 31 in the ECU 30 to perform the same operations and effects as in the above-described embodiment.
[0041]
By the way, in the above embodiment, an internal combustion engine having four cylinders and three cylinders has been described. However, the present invention is not limited to this, and may be applied to an internal combustion engine having a plurality of cylinders. Thus, a similar effect can be obtained.
[0042]
In the above embodiment, the crank angle sensor 23 is used as the rotation angle detecting means for detecting the rotation angle of the crankshaft 13 of the internal combustion engine 1. However, the present invention is not limited to this. Instead, a signal from a cam angle sensor that detects the rotation angle of a camshaft (not shown) for opening and closing the intake valve 6 or the exhaust valve 8 may be used.
[0043]
In the above-described embodiment, the application to the so-called DJ system in which the fuel pressure is set by detecting the intake pressure in the intake passage has been described. However, the present invention is not limited to this. In addition, the present invention is particularly effective for application to an internal combustion engine having an exhaust turbine supercharger (Turbocharger; hereinafter, simply referred to as “T / C”) in a DJ system. That is, in the case of an internal combustion engine provided with T / C in the DJ system, the torque difference between the cylinders is widened even in a state where the operating condition is little changed. Pulsation tends to increase. In the case where there is such a phenomenon, there is a possibility that the acceleration is erroneously determined due to the intake pulsation even in a state where the change in the operating condition is small. When the fuel increase / decrease amount is set by this acceleration determination, as a result, fluctuations in the engine rotational speed occur.In an internal combustion engine to which the internal combustion engine control device according to the present invention is applied, By appropriately correcting the ignition timing and the fuel injection amount based on the intake pressure change amount, the effect of eliminating torque fluctuation between cylinders can be expected.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an internal combustion engine to which a control device for an internal combustion engine according to a first embodiment of the present invention is applied and peripheral devices thereof.
FIG. 2 is a flowchart illustrating a cylinder identification processing procedure in a CPU in an ECU used in a control device for an internal combustion engine according to a first example of an embodiment of the present invention.
FIG. 3 is a flowchart showing a processing procedure of inter-cylinder torque fluctuation correction / learning in a CPU in an ECU used in a control device for an internal combustion engine according to a first embodiment of the present invention. .
FIG. 4 is a schematic configuration diagram showing an internal combustion engine to which an internal combustion engine control device according to a second example of the embodiment of the present invention is applied and peripheral devices thereof.
FIG. 5 is a flowchart showing a processing procedure of inter-cylinder torque fluctuation correction by a CPU in an ECU used in a control device for an internal combustion engine according to a second embodiment of the present invention.
FIG. 6 is a time chart showing transition states of various sensor signals, various control amounts, and the like corresponding to the processing of FIG. 5;
[Explanation of symbols]
1 Internal combustion engine
2 Intake passage
5 Injector (fuel injection valve)
11 Throttle valve
21 Throttle opening sensor
22 Intake pressure sensor
23 Crank angle sensor
24 Knock sensor
25 A / F sensor
30 ECU (electronic control unit)

Claims

Intake pressure detecting means for detecting an intake pressure downstream of a throttle valve in an intake passage of an internal combustion engine comprising a plurality of cylinders;
Rotation angle detection means for detecting a rotation angle of a crankshaft or a camshaft of the internal combustion engine,
The intake pressure change amount of the average intake pressure of each cylinder obtained by averaging the intake pressure by the intake pressure detection unit for each combustion interval, and the intake pressure change amount that is the sum of the intake pressure change amounts of all cylinders A cylinder identifying means for identifying a cylinder having a large change,
A control device for an internal combustion engine, comprising: a fluctuation correcting means for correcting a torque fluctuation between cylinders by advancing or retarding an ignition timing with respect to the cylinder specified by the cylinder specifying means.

Intake pressure detecting means for detecting an intake pressure downstream of a throttle valve in an intake passage of an internal combustion engine comprising a plurality of cylinders;
Rotation angle detection means for detecting a rotation angle of a crankshaft or a camshaft of the internal combustion engine,
The intake pressure change amount of the average intake pressure of each cylinder obtained by averaging the intake pressure by the intake pressure detection unit for each combustion interval, and the intake pressure change amount that is the sum of the intake pressure change amounts of all cylinders A cylinder identifying means for identifying a cylinder having a large change,
A control device for an internal combustion engine, comprising: a fluctuation correcting unit that corrects a torque fluctuation between cylinders by increasing or decreasing a fuel injection amount with respect to the cylinder specified by the cylinder specifying unit.

Intake pressure detecting means for detecting an intake pressure downstream of a throttle valve in an intake passage of an internal combustion engine comprising a plurality of cylinders;
Rotation angle detection means for detecting a rotation angle of a crankshaft or a camshaft of the internal combustion engine,
Vibration detection means for detecting a vibration waveform signal generated in the internal combustion engine,
Knock determination means for determining the presence or absence of knock based on the vibration waveform signal by the vibration detection means,
The intake pressure change amount of the average intake pressure of each cylinder obtained by averaging the intake pressure by the intake pressure detection unit for each combustion interval, and the intake pressure change amount that is the sum of the intake pressure change amounts of all cylinders A cylinder identifying means for identifying a cylinder having a large change,
And a fluctuation correcting means for correcting a torque fluctuation between the cylinders by advancing or retarding the ignition timing with respect to the cylinder specified by the cylinder specifying means based on a determination result by the knock determining means. A control device for an internal combustion engine.

Intake pressure detecting means for detecting an intake pressure downstream of a throttle valve in an intake passage of an internal combustion engine comprising a plurality of cylinders;
Rotation angle detection means for detecting a rotation angle of a crankshaft or a camshaft of the internal combustion engine,
Air-fuel ratio detection means for detecting the air-fuel ratio of the exhaust gas in the exhaust passage of the internal combustion engine,
The intake pressure change amount of the average intake pressure of each cylinder obtained by averaging the intake pressure by the intake pressure detection unit for each combustion interval, and the intake pressure change amount that is the sum of the intake pressure change amounts of all cylinders A cylinder identifying means for identifying a cylinder having a large change,
And a fluctuation correcting unit that corrects a torque fluctuation between the cylinders by increasing or decreasing a fuel injection amount for the cylinder specified by the cylinder specifying unit based on a detection result by the air-fuel ratio detecting unit. A control device for an internal combustion engine.

The control device for an internal combustion engine according to any one of claims 1 to 4, wherein the internal combustion engine includes an exhaust turbine supercharger.