JP3869634B2 - Air-fuel ratio feedback control device for internal combustion engine - Google Patents

Air-fuel ratio feedback control device for internal combustion engine Download PDF

Info

Publication number
JP3869634B2
JP3869634B2 JP2000214174A JP2000214174A JP3869634B2 JP 3869634 B2 JP3869634 B2 JP 3869634B2 JP 2000214174 A JP2000214174 A JP 2000214174A JP 2000214174 A JP2000214174 A JP 2000214174A JP 3869634 B2 JP3869634 B2 JP 3869634B2
Authority
JP
Japan
Prior art keywords
air
fuel ratio
exhaust
cylinder
estimated
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP2000214174A
Other languages
Japanese (ja)
Other versions
JP2002030968A (en
Inventor
秀和 吉澤
肇 細谷
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP2000214174A priority Critical patent/JP3869634B2/en
Priority to US09/897,925 priority patent/US6708681B2/en
Publication of JP2002030968A publication Critical patent/JP2002030968A/en
Application granted granted Critical
Publication of JP3869634B2 publication Critical patent/JP3869634B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Description

【０００１】
【発明の属する技術分野】
本発明は、燃焼混合気の空燃比を目標空燃比にフィードバック補正する内燃機関の空燃比フィードバック制御装置に関する。
【０００２】
【従来の技術】
従来から、目標空燃比の混合気による燃焼を行わせるべく、空燃比センサで検出される排気空燃比と目標空燃比との偏差に基づいて、燃料噴射弁による燃料噴射量をフィードバック補正する構成の空燃比フィードバック制御装置が知られている（特開平６−１０８９０１号公報等参照）。
【０００３】
【発明が解決しようとする課題】
ところで、空燃比センサで検出した排気空燃比に基づいて燃料噴射量を補正した結果が、空燃比センサで検出されるまでには、燃焼排気の輸送遅れによるむだ時間がある。
【０００４】
そのため、過剰なゲインでフィードバック制御を行うと、大きなオーバーシュートを発生させることになり、オーバーシュートを抑止しつつ収束応答性を確保できるゲインの設定が必要になる。
【０００５】
そこで、従来では、前記むだ時間に相関する機関の吸入空気量及び回転速度毎に予め最適なゲインを求め、これをマップに記憶させ、そのときの吸入空気量と回転速度に対応するゲインを前記マップから検索してフィードバック制御を行わせるようにしていた。
【０００６】
従って、従来では、ゲインの適合工数が必要であると共に、運転条件毎のゲインを記憶するマップのために多くの記憶容量が必要であり、更に、大きなオーバーシュートを回避するために高い応答性で空燃比（Ａ／Ｆ）をフィードバック制御することできないという問題があった。
【０００７】
本発明は上記問題点に鑑みなされたものであり、燃料噴射量の補正結果が検出されるまでのむだ時間をなくして、運転条件毎のむだ時間に応じたゲインの設定が不要で、かつ、高い応答で空燃比を補正できる内燃機関の空燃比フィードバック制御装置を提供することを目的とする。
【０００８】
【課題を解決するための手段】
そのため、請求項１記載の発明では、シリンダ内に形成される混合気の空燃比を推定し、該推定したシリンダ内空燃比に基づいて燃料噴射量を補正するための空燃比補正値を演算するよう構成する一方、前記推定したシリンダ内空燃比に基づき前記空燃比センサで検出される排気空燃比を推定し、該推定した排気空燃比と前記空燃比センサで検出された排気空燃比に基づいて、前記シリンダ内空燃比の推定値を補正するよう構成される共に、前記シリンダ内空燃比の推定において、前記空燃比補正値及び目標空燃比に基づき初期空燃比を演算し、体積効率，大気圧，吸気圧，圧縮比に基づいて新気割合を演算し、前記初期空燃比と新気割合とに基づいてシリンダ内空燃比を演算するよう構成した。
【０００９】
かかる構成によると、シリンダ内空燃比を推定し、該推定気結果を目標空燃比に一致させるように燃料噴射量をフィードバック制御する一方、推定したシリンダ内空燃比が遅れて空燃比センサで検出されることに基づき、空燃比センサによって検出される排気空燃比を推定し、該推定値と実際に空燃比センサで検出された排気空燃比とから、シリンダ内空燃比の推定誤差を修正する。ここで、空燃比補正値（空燃比フィードバック補正係数）と目標空燃比に基づき、燃料噴射量の演算上における空燃比である初期空燃比を求め、更に、シリンダ内の残留ガスで変化する新気割合で初期空燃比を修正して、シリンダ内に新気と噴射燃料とで形成される混合気の空燃比を推定するものとし、更に、シリンダ内の残留ガスで変化する新気の割合を、体積効率，大気圧，吸気圧，圧縮比に基づき推定する。
請求項２記載の発明では、シリンダ内に形成される混合気の空燃比を推定し、該推定したシリンダ内空燃比に基づいて燃料噴射量を補正するための空燃比補正値を演算するよう構成する一方、排気の輸送遅れ時間を、シリンダから前記空燃比センサまでの排気配管体積及び排気ガスの体積流量に基づき演算し、前記シリンダ内空燃比の推定値と前記排気の輸送遅れ時間に基づき、前記空燃比センサで検出される排気空燃比を推定し、該推定した排気空燃比と前記空燃比センサで検出された排気空燃比に基づいて、前記シリンダ内空燃比の推定値を補正するよう構成した。
かかる構成によると、シリンダで燃焼した燃焼ガスが、排気配管の途中に設けられる空燃比センサに到達するまでには時間を要するので、シリンダ内空燃比の推定値と前記到達に要する時間（輸送遅れ時間）に基づき、シリンダ内空燃比の推定値が前記輸送遅れ時間が経過した後で空燃比センサで検出されるものとして、空燃比センサによる検出値を推定し、該推定値と実際に空燃比センサで検出された排気空燃比とから、シリンダ内空燃比の推定誤差を修正する。ここで、シリンダから空燃比センサまでの排気配管体積を、排気で満たすのに要する時間として、排気の輸送遅れ時間を求める。
【００１０】
請求項３記載の発明では、請求項２記載の発明において、空燃比補正値及び目標空燃比に基づき初期空燃比を演算し、該初期空燃比と新気割合とに基づいてシリンダ内空燃比を演算する構成とした。
【００１１】
かかる構成によると、空燃比補正値（空燃比フィードバック補正係数）と目標空燃比に基づき、燃料噴射量の演算上における空燃比である初期空燃比を求め、更に、シリンダ内の残留ガスで変化する新気割合で初期空燃比を修正して、シリンダ内に新気と噴射燃料とで形成される混合気の空燃比を推定する。
【００１２】
請求項４記載の発明では、請求項３記載の発明において、新気割合を、体積効率，大気圧，吸気圧，圧縮比に基づいて演算する構成とした。
【００１３】
かかる構成によると、シリンダ内の残留ガスで変化する新気の割合を、体積効率，大気圧，吸気圧，圧縮比に基づき推定する。
【００１４】
請求項５記載の発明では、請求項１〜４のいずれか１つに記載の発明において、シリンダ内空燃比の推定値を、空燃比センサの動特性に基づき補正する構成とした。
【００１５】
かかる構成によると、実際の排気空燃比の変化に対して検出値の変化が遅れる空燃比センサの動特性に基づき、シリンダ内空燃比を補正することで、シリンダ内空燃比を空燃比センサで検出させたと仮定した場合の検出結果を推定させ、このシリンダ内空燃比の空燃比センサによる検出推定値に基づき、フィードバック制御を行わせる。即ち、見掛け上、シリンダ内の空燃比を直接空燃比センサで検出させて空燃比フィードバックを行わせる構成とする。
【００１６】
請求項６記載の発明では、請求項１記載の発明において、シリンダ内空燃比の推定値と排気の輸送遅れ時間に基づき、空燃比センサで検出される排気空燃比を推定する構成とした。
【００１７】
かかる構成によると、シリンダで燃焼した燃焼ガスが、排気配管の途中に設けられる空燃比センサに到達するまでには時間を要するので、シリンダ内空燃比と前記到達に要する時間（輸送遅れ時間）に基づき、シリンダ内空燃比の推定値が前記輸送遅れ時間が経過した後で空燃比センサで検出されるものとして、空燃比センサによる検出値を推定する。
【００１８】
請求項７記載の発明では、請求項６記載の発明において、排気の輸送遅れ時間を、シリンダから空燃比センサまでの排気配管体積及び排気ガスの体積流量に基づき演算する構成とした。
【００１９】
かかる構成によると、シリンダから空燃比センサまでの排気配管体積を、排気で満たすのに要する時間として、排気の輸送遅れ時間が求められる。
【００２０】
請求項８記載の発明では、請求項１〜７のいずれか１つに記載の発明において、前記推定した排気空燃比と前記空燃比センサで検出された排気空燃比との偏差を、所定の伝達関数に入力し、該伝達関数の出力で前記シリンダ内空燃比を補正する構成とした。
【００２１】
かかる構成によると、シリンダ内空燃比に基づき空燃比センサ部での空燃比を推定したときの推定誤差が、空燃比センサで実際に検出された排気空燃比との比較で求められ、該誤差からシリンダ内空燃比の推定値を補正するために、空燃比センサ部で推定誤差を伝達関数に入力してシリンダ内空燃比の推定誤差を修正するための補正値に変換する。
【００２２】
一方、請求項９記載の発明は、排気空燃比を検出する空燃比センサと、燃料噴射量を補正するための空燃比補正値とそのときの目標空燃比に基づいて初期空燃比を演算する手段と、新気割合を運転条件に応じて演算する手段と、前記初期空燃比と新気割合に基づいてシリンダ内空燃比を演算する手段と、前記シリンダ内空燃比に空燃比センサの動特性に応じた補正を施して最終的な推定空燃比を演算する手段と、空燃比センサまでの排気輸送遅れ時間を演算する手段と、前記推定空燃比と前記排気輸送遅れ時間に基づいて空燃比センサで検出される排気空燃比を演算する手段と、該手段で演算された排気空燃比と前記空燃比センサで検出された排気空燃比に基づいて外乱補正値を演算する手段と、前記目標空燃比，推定空燃比及び外乱補正値に基づいて空燃比補正値を演算する手段と、前記空燃比補正値に基づいて燃料噴射量を補正する手段と、を含んで構成される。
【００２３】
かかる構成によると、まず、空燃比補正値と目標空燃比とから噴射量の演算上における空燃比を初期空燃比として求め、該初期空燃比と新気割合とからシリンダ内に形成される混合気の空燃比を求める。更に、該シリンダ内の混合気の空燃比を空燃比センサで検出させた場合を想定して、シリンダ内の空燃比変化に対して遅れる空燃比センサの検出結果を推定し、これを最終的なシリンダ内空燃比の推定値とする。
【００２４】
ここで、実際には、空燃比センサはシリンダ部ではなく排気配管の途中に設けられ、排気の輸送遅れ時間だけシリンダ内空燃比を遅れて検出するので、シリンダ内空燃比が排気の輸送遅れ時間だけ遅れて空燃比センサで検出されるものとして、空燃比センサで検出されるはずの空燃比を推定する。そして、空燃比センサで検出されるものとして推定した空燃比と、実際に空燃比センサで検出された空燃比とから、空燃比の推定誤差に対応する外乱補正値を設定し、該外乱補正値，目標空燃比，シリンダ内空燃比から燃料噴射量を補正するための空燃比補正値を演算する。
請求項１０記載の発明は、シリンダ内に形成される混合気の空燃比を推定し、該推定したシリンダ内空燃比に基づいて燃料噴射量を補正するための空燃比補正値を演算するよう構成する一方、前記推定したシリンダ内空燃比に前記空燃比センサの動特性に応じた補正を施すと共に、前記空燃比センサまでの排気輸送遅れ時間を演算し、前記動特性に応じた補正が施されたシリンダ内空燃比の推定値の前記排気輸送遅れ時間だけ前のデータと、前記空燃比センサで検出された排気空燃比とに基づいて、前記シリンダ内空燃比の推定値を補正する構成とした。
かかる構成によると、実際の排気空燃比の変化に対して検出値の変化が遅れる空燃比センサの動特性に基づき、シリンダ内空燃比を補正することで、シリンダ内空燃比を空燃比センサで検出させたと仮定した場合の検出結果を推定させる。そして、推定値の排気輸送遅れ時間だけ前のデータが、空燃比センサで検出されるはずの空燃比とし、この空燃比と実際に空燃比センサで検出された空燃比とから、シリンダ内空燃比の推定値を補正する。
【００２５】
【発明の効果】
請求項１記載の発明によると、シリンダ内の空燃比を推定して空燃比フィードバック制御を行うので、むだ時間のないフィードバック制御を行わせることができ、むだ時間の変化に対応するためのゲインの適合・記憶が不要になると共に、高い応答で補正を行わせることができる一方、機関の運転条件及び環境条件によって変化する新気割合を精度良く推定し、該新気割合と燃料噴射制御上の空燃比とからシリンダ内に形成される混合気の空燃比を精度良く推定でき、更に、シリンダ内の空燃比の推定誤差を空燃比センサを用いて修正して、高い精度で空燃比を制御できるという効果がある。
請求項２記載の発明によると、推定したシリンダ空燃比が排気の輸送遅れ時間が経過してから空燃比センサで検出されることに対応して、空燃比センサで検出されることになる空燃比を推定でき、更に、排気の輸送遅れ時間をそのときの排気体積流量に基づいて精度良く推定できるという効果がある。
【００２６】
請求項３記載の発明によると、燃料噴射制御上の空燃比と、新気割合とからシリンダ内に形成される混合気の空燃比を精度良く推定できるという効果がある。
【００２７】
請求項４記載の発明によると、機関の運転条件及び環境条件によって変化する新気割合を精度良く推定できるという効果がある。
【００２８】
請求項５記載の発明によると、シリンダ内の空燃比を空燃比センサで直接検出させた場合に相当する空燃比の推定結果が得られ、空燃比センサによる検出結果に基づいて空燃比をフィードバック制御する構成に対して、排気の輸送遅れ時間によるむだ時間を無くした制御システムを構築できるという効果がある。
【００２９】
請求項６記載の発明によると、推定したシリンダ空燃比が排気の輸送遅れ時間が経過してから空燃比センサで検出されることに対応して、空燃比センサで検出されることになる空燃比を推定できるという効果がある。
【００３０】
請求項７記載の発明によると、排気の輸送遅れ時間をそのときの排気体積流量に基づいて精度良く推定できるという効果がある。
【００３１】
請求項８記載の発明によると、空燃比センサ部における空燃比の推定誤差からシリンダ内空燃比の推定誤差を精度良く補正することができるという効果がある。
【００３２】
請求項９記載の発明によると、シリンダ内の空燃比を空燃比センサで直接検出させた場合の検出結果を推定して、空燃比をフィードバック制御するので、排気の輸送遅れ時間を見掛け上無くして制御を行わせることができ、むだ時間の変化に対応するためのゲインの適合・記憶が不要になると共に、高い応答で補正を行わせることができる一方、前記シリンダ内空燃比の推定値の誤差を実際に空燃比センサで検出された結果から精度良く修正でき、目標空燃比に高い精度でフィードバック制御することができるという効果がある。
請求項１０記載の発明によると、空燃比センサの動特性と排気輸送遅れ時間とに対応して、空燃比センサで検出されることになる空燃比を推定して、シリンダ内の空燃比の推定誤差を高精度に修正できるという効果がある。
【００３３】
【発明の実施の形態】
以下に本発明の実施の形態を説明する。
【００３４】
図１は実施の形態における内燃機関のシステム構成図である。
この図１において、車両に搭載される内燃機関１の各気筒の燃焼室には、エアクリーナ２，吸気通路３，モータで開閉駆動される電子制御式スロットル弁４を介して空気が吸入される。
【００３５】
各気筒の燃焼室内に燃料（ガソリン）を直接噴射する電磁式の燃料噴射弁５が設けられており、該燃料噴射弁５から噴射される燃料と前記吸入される空気とによって燃焼室内に混合気が形成される。
【００３６】
燃料噴射弁５は、コントロールユニット２０から出力される噴射パルス信号によりソレノイドに通電されて開弁し、所定圧力に調圧された燃料を噴射する。そして、噴射された燃料は、吸気行程噴射の場合は燃焼室内に拡散して均質な混合気を形成し、また圧縮行程噴射の場合は点火栓６回りに集中的に層状の混合気を形成する。燃焼室内に形成される混合気は、点火栓６により着火燃焼する。
【００３７】
但し、内燃機関1を上記の直接噴射式ガソリン機関に限定するものではなく、吸気ポートに燃料を噴射する構成の機関であっても良い。
【００３８】
機関１からの排気は排気通路７より排出され、該排気通路７には排気浄化用の触媒８が介装されている。
【００３９】
また、燃料タンク９にて発生した蒸発燃料を燃焼処理する蒸発燃料処理装置が設けられている。
【００４０】
キャニスタ１０は、密閉容器内に活性炭などの吸着剤１１を充填したもので、燃料タンク９から延設される蒸発燃料導入管１２が接続されている。従って、燃料タンク９にて発生した蒸発燃料は、前記蒸発燃料導入管１２を通って、キャニスタ１０に導かれ吸着捕集される。
【００４１】
また、キャニスタ１０には、新気導入口１３が形成されると共に、パージ配管１４が導出され、前記パージ配管１４には、コントロールユニット２０からの制御信号によって開閉が制御されるパージ制御弁１５が介装される。
【００４２】
上記構成において、パージ制御弁１５が開制御されると、機関１の吸入負圧がキャニスタ１０に作用する結果、新気導入口１３から導入される空気によってキャニスタ１０の吸着剤１１に吸着されていた蒸発燃料がパージされ、パージエアがパージ配管１４を通って吸気通路３のスロットル弁４下流に吸入され、その後、機関１の燃焼室内で燃焼処理される。
【００４３】
コントロールユニット２０は、ＣＰＵ，ＲＯＭ，ＲＡＭ，Ａ／Ｄ変換器及び入出力インターフェイス等を含んで構成されるマイコンを備え、各種センサからの入力信号を受け、これらに基づいて演算処理して、燃料噴射弁５，点火栓６及びパージ制御弁１５などの作動を制御する。
【００４４】
前記各種センサとして、機関１のクランク角を検出するクランク角センサ２１、カム軸から気筒判別信号を取り出すカムセンサ２２が設けられており、前記クランク角センサ２１からの信号に基づき機関の回転速度Ｎｅが算出される。
【００４５】
この他、吸気通路３のスロットル弁４上流側で吸入空気流量Ｑ（質量流量）を検出するエアフローメータ２３、アクセルペダルの踏込み量（アクセル開度）ＡＰＳを検出するアクセルセンサ２４、スロットル弁４の開度ＴＶＯを検出するスロットルセンサ２５、機関１の冷却水温Ｔｗを検出する水温センサ２６、排気中の酸素濃度に応じて燃焼混合気の空燃比をリニアに検出する広域型の空燃比センサ２７、車速ＶＳＰを検出する車速センサ２８などが設けられている。
【００４６】
ここで、前記広域型の空燃比センサ２７の構造を、図２に基づいて説明する。ジルコニア（ＺｒＯ2）等の固体電解質部材からなる基板３１上に、酸素濃度測定用の＋電極３２が設けられている。また、前記基板３１内には、大気が導入される中空部３３が開設され、この中空部３３の天井部には、−電極３４が基板３１を挟んで＋電極３２に対向するように取り付けられており、前記基板３１と＋電極３２と−電極３４とにより酸素濃度検出部３５が形成される。
【００４７】
また、ジルコニア等からなる固体電解質部材３６の両面に一対の白金からなるポンプ電極３７，３８を設けて形成される酸素ポンプ部３９を有している。
【００４８】
そして、該酸素ポンプ部３９を、例えばアルミナで枠状に形成したスペーサ４０を介して酸素濃度検出部３５の上方に積層して、酸素濃度検出部３５と酸素ポンプ部３９との間に中空室４１が設けられ、かつ、この中空室４１に機関の排気を導入するための導入孔４２が酸素ポンプ部３９の固体電解質部材３６に形成されている。
【００４９】
尚、前記スペーサ４０の外周にはガラス製の接着剤４３が充填され、中空室４１の密閉性を確保すると共に、基板３１及びスペーサ４０と固体電解質３６とを接着固定するようにしてある。ここで、スペーサ４０と基板３１とは同時焼成して結合されるため、中空室４１の密閉性はスペーサ４０と固体電解質部材３６とを接着することによって確保されるものである。また、酸素濃度検出部３９には、加熱用のヒーター４４が内蔵されている。
【００５０】
そして、導入孔４２を介して中空室４１に導入された排気の酸素濃度を前記＋電極３２の電圧から検出する。具体的には、中空部３３内の大気中の酸素と中空室４１内の排気中の酸素との濃度差に応じて基板３１内を酸素イオンが流れ、これに伴って、＋電極３２に排気中の酸素濃度に対応する起電力が発生する。
【００５１】
そして、この検出結果に応じて中空室４１内の雰囲気を一定（例えば理論空燃比) に保つように酸素ポンプ部３９に流す電流値を制御し、その時の電流値から排気中の酸素濃度（排気空燃比）を検出する。
【００５２】
具体的には、前記＋電極３２の電圧を、制御回路４５によって増幅処理した後、電圧検出抵抗４６を介して電極３７，３８間に印加し、中空室４１内の酸素濃度を一定に保つようにする。
【００５３】
例えば、排気中の酸素濃度の高いリーン領域での空燃比を検出する場合には、外側のポンプ電極３７を陽極、中空室４１側のポンプ電極３８を陰極にして電圧を印加する。すると、電流に比例した酸素（酸素イオンＯ2- )が中空室４１から外側に汲み出される。そして、印加電圧が所定値以上になると、流れる電流は限界値に達し、この限界電流値を前記制御回路４５で測定することにより排気中の酸素濃度、換言すれば、排気空燃比を検出できる。
【００５４】
逆に、ポンプ電極３７を陰極、ポンプ電極３８を陽極にして中空室４１内に酸素を汲み入れるようにすれば、排気中の酸素濃度の低い空燃比リッチ領域での空燃比検出が行える。
【００５５】
上記限界電流は、前記電圧検出抵抗４６の端子間電圧を検出する差動増幅器４７の出力電圧から検出される。
【００５６】
前記コントロールユニット２０は、所定の空燃比フィードバック制御条件が成立するときに、燃焼混合気の空燃比を目標空燃比に一致させるべく、本発明に係る空燃比フィードバック制御を行なう。
【００５７】
図３のブロック図は、前記空燃比フィードバック制御を示すものであり、スライディングモードコントローラ５１（空燃比補正値演算手段）には、後述するようにして演算される推定空燃比と目標空燃比との偏差（エラー）が入力され、該偏差に基づいて燃料噴射量を補正するための空燃比フィードバック補正係数ＡＬＰＨＡ（空燃比補正値）を出力する。
【００５８】
前記空燃比フィードバック補正係数ＡＬＰＨＡは、燃料噴射量演算部５２（噴射量補正手段）に入力され、ここで、基本燃料噴射量を前記空燃比フィードバック補正係数ＡＬＰＨＡで補正して最終的な燃料噴射量Ｔｉが算出され、該燃料噴射量Ｔｉに相当するパルス幅の噴射パルス信号が、機関１の燃料噴射弁５に出力される。
【００５９】
図４は前記スライディングモードコントローラ５１の詳細を示すブロック図であり、前記偏差（エラー）に基づいて線形項Ｕ１を演算する線形項演算部５１１と、前記偏差（エラー）に基づいて非線形項Ｕ２を演算する非線形項演算部５１２とからなり、線形項Ｕ１＋非線形項Ｕ２＝ＡＬＰＨＡとして、空燃比フィードバック補正係数ＡＬＰＨＡを出力する。
【００６０】
前記線形項演算部５１１は、エラー×ゲイン、∫（エラー）×ゲイン、目標空燃比×ゲインをそれぞれ演算し、これらの演算結果を総和して線形項Ｕ１を算出するものであり、詳細には、エラーをx1、αi,ａi,ｂ(i:1,2,3)を係数とすると、
Ｕ１＝1/ｂ((a0−α3−α1(a1−α1))x1−α3(a1−α1)∫（x1）＋a0r)
として、線形項Ｕ１を算出する。
【００６１】
一方、非線形項演算部５１２は、切換関数をσ、チャタリング防止係数をδ、係数をＫとしたときに、
σ＝α１・x1＋ｄ（x1）/ｄｔ＋α３∫（x1）
Ｕ２＝Ｋ・σ／（｜σ｜＋δ）
として、非線形項Ｕ２を算出する。
【００６２】
尚、本実施形態では、スライディングモードによって偏差（エラー）から空燃比フィードバック補正係数ＡＬＰＨＡを算出させる構成としたが、比例積分動作（ＰＩ）或いは比例積分微分動作（ＰＩＤ）によって、空燃比フィードバック補正係数ＡＬＰＨＡを算出する構成としても良い。
【００６３】
例えば、比例積分微分動作（ＰＩＤ）によって空燃比フィードバック補正係数ＡＬＰＨＡを算出する場合には、比例ゲインをＫｐ，積分ゲインをＫｉ、微分ゲインをＫｄとしたときに、
ＡＬＰＨＡ＝Ｋｐ・x1＋Ｋｉ・∫（x1）＋Ｋｄ・ｄ（x1）/ｄｔ
として空燃比フィードバック補正係数ＡＬＰＨＡが算出される。
【００６４】
また、図４に示す構成とは異なる構成のスライディングモードで空燃比フィードバック補正係数ＡＬＰＨＡを算出させる構成としても良く、推定空燃比を目標空燃比に近づけるように空燃比フィードバック補正係数ＡＬＰＨＡを算出する構成であれば、公知の如何なる構成も適用可能である。
【００６５】
一方、前記空燃比偏差（エラー）の演算に用いられる推定空燃比を算出するための構成として、空燃比推定部５３、むだ時間後空燃比推定部５４、外乱補償器５５が設けられている。
【００６６】
図５は、前記空燃比推定部５３の詳細を示すものであり、初期空燃比演算部５３１（初期空燃比演算手段）には、前記空燃比フィードバック補正係数ＡＬＰＨＡ及び目標当量比ＴＦＢＹＡが入力され、初期空燃比を、
初期空燃比＝係数／（ＡＬＰＨＡ×ＴＦＢＹＡ）
として算出する。
【００６７】
燃料噴射量は、理論空燃比相当の噴射量×ＴＦＢＹＡ×ＡＬＰＨＡとして算出されることになるから、ＡＬＰＨＡ×ＴＦＢＹＡは燃料噴射量の演算上における当量比となり、この当量比の逆数に係数を乗算して空燃比に変換している。
【００６８】
前記初期空燃比はシリンダ内空燃比演算部５３２（シリンダ内空燃比演算手段）に入力され、該シリンダ内空燃比演算部５３２では、そのときの新気割合ηと前記初期空燃比とからシリンダ内空燃比を下式に従って算出する。
【００６９】
シリンダ内空燃比＝η×初期空燃比＋（１−η）×シリンダ内空燃比（old）前記新気割合ηは新気割合演算部５３３（新気割合演算手段）で算出される。
【００７０】
前記新気割合演算部５３３には、機関回転速度Ｎｅ，エアフローメータ２３で検出された吸入空気流量，大気圧，吸気圧が入力され、下式に従って新気割合ηを算出する。
【００７１】
η＝ηｖ×（大気圧／吸気圧）×（（ε−１）／ε）
ここで、ηｖは体積効率であり、機関回転速度Ｎｅ，吸入空気流量に基づき設定される。また、εは圧縮比である。
【００７２】
尚、大気圧，吸気圧は、それぞれを検出するセンサを設ける構成としても良いし、また、運転条件から推定させることも可能である。
【００７３】
前記シリンダ内空燃比演算部５３２で算出されたシリンダ内空燃比は、１次遅れ補正部５３４に入力される。
【００７４】
前記１次遅れ補正部５３４は、前記シリンダ内空燃比を空燃比センサ２７で検出させた場合、換言すれば、シリンダ内に空燃比センサ２７を設置したと仮定した場合の空燃比センサ２７による検出空燃比を推定するものである。
【００７５】
空燃比センサ２７は、酸素濃度（空燃比）の変化に対して１次遅れをもって応答する動特性を有するので、前記１次遅れ補正部５３４（推定空燃比演算手段）は、前記シリンダ内空燃比に１次遅れ補正を施して、これをシリンダ内空燃比を空燃比センサ２７で検出させた場合の検出結果として推定する。
【００７６】
具体的には、空燃比センサ２７による検出空燃比の推定値を推定空燃比とすると、

Figure 0003869634
として推定空燃比を算出する。
【００７７】
前記１次遅れ補正部５３４で算出される推定空燃比は、排気輸送遅れ（むだ時間）がない条件での空燃比を推定することになり、該推定空燃比に基づいて空燃比フィードバック制御（スライディングモードコントローラ５１における補正係数ＡＬＰＨＡの演算）を行わせる構成とすれば、むだ時間の変化に対応するためのゲインの適合・記憶が不要になると共に、高い応答で補正を行わせることができる。
【００７８】
但し、前記推定空燃比は、外乱の影響で実際の空燃比からずれることになるため、前記空燃比センサ２７を用いて前記推定空燃比を修正するようにしてあり、具体的には、むだ時間後空燃比推定部５４，外乱補償器５５によって前記修正が行われる。
【００７９】
前記むだ時間後空燃比推定部５４は、図６に示すように、排気輸送遅れ時間算出部５４１と、排気輸送遅れ後空燃比算出部５４２とから構成される。
【００８０】
排気輸送遅れ時間算出部５４１（輸送遅れ時間演算手段）は、排気輸送遅れ時間を、シリンダから空燃比センサ２７までの排気配管容積と、排気ガス体積流量とから、
排気輸送遅れ時間＝排気配管容積／排気ガス体積流量
として算出する。
【００８１】
ここで、前記排気配管容積は固定値であるので予め記憶させておく。また、排気ガス体積流量は、エアフローメータ２３で検出される吸入空気の質量流量を排気の質量流量と見做し、該排気ガス質量流量と排気温度とから体積流量を算出させる。
【００８２】
排気輸送遅れ後空燃比算出部５４２（排気空燃比演算手段）は、過去所定時間内に前記１次遅れ補正部５３４で算出された推定空燃比を時系列に記憶し、この時系列に記憶される複数の推定空燃比のデータの中から、前記排気輸送遅れ時間だけ前のデータを検索して、排気輸送遅れ後空燃比（排気空燃比）として出力する。
【００８３】
即ち、前記１次遅れ補正部５３４で算出された推定空燃比はシリンダ内空燃比であり、該空燃比の排気は、前記排気輸送遅れ時間が経過してから空燃比センサ２７に到達することになり、現時点で空燃比センサ２７で検出されることになる排気空燃比は、前記排気輸送遅れ時間だけ前のシリンダ内空燃比ということになる。
【００８４】
前記排気輸送遅れ後空燃比は空燃比センサ２７による検出空燃比と共に外乱補償器５５（外乱補正値演算手段）に入力され、該外乱補償器５５では、前記空燃比センサ２７による検出空燃比と前記排気輸送遅れ後空燃比（推定排気空燃比）との偏差を、予め設定された伝達関数に入力して、その出力を推定空燃比の補正値（外乱補正値）として出力する。
【００８５】
前記空燃比センサ２７による検出空燃比と前記排気輸送遅れ後空燃比との偏差は、前記排気輸送遅れ後空燃比の誤差を示すが、シリンダ内空燃比である推定空燃比を補正する必要があるため、前記偏差からシリンダ内空燃比である推定空燃比が適正に補正されるように伝達関数を予めシステム同定させてある。
【００８６】
前記外乱補償器５５の出力は、前記１次遅れ補正部５３４から出力される推定空燃比に加算され、該加算によって修正された推定空燃比と、目標空燃比との偏差に基づいて空燃比フィードバック補正係数ＡＬＰＨＡを演算させる。従って、外乱によって推定空燃比に大きな誤差が生じることを防止でき、高い精度で目標空燃比にフィードバック制御できる。
【００８７】
尚、本実施形態では、外乱補償器５５の出力で推定空燃比を補正してから、目標空燃比に対する偏差を求めさせる構成としたが、例えば、目標空燃比を外乱補償器５５の出力で補正し、該補正後の目標空燃比と推定空燃比との偏差を演算させるようにしても、実質的な違いはない。
【図面の簡単な説明】
【図１】実施の形態における内燃機関のシステム構成図。
【図２】実施の形態における空燃比センサ及びその周辺回路を示す図。
【図３】実施の形態における空燃比フィードバック制御の構成を示すブロック図。
【図４】実施の形態におけるスライディングモードコントローラを示すブロック図。
【図５】実施の形態における空燃比推定部を示すブロック図。
【図６】実施の形態におけるむだ時間後空燃比推定部を示すブロック図。
【符号の説明】
１…内燃機関
３…吸気通路
４…スロットル弁
５…燃料噴射弁
２０…コントロールユニット
２７…空燃比センサ
５１…スライディングモードコントローラ
５２…燃料噴射量演算部
５３…空燃比推定部
５４…むだ時間後空燃比推定部
５５…外乱補償器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air-fuel ratio feedback control device for an internal combustion engine that feedback corrects an air-fuel ratio of a combustion mixture to a target air-fuel ratio.
[0002]
[Prior art]
Conventionally, in order to perform combustion with an air-fuel mixture of a target air-fuel ratio, the fuel injection amount by the fuel injection valve is feedback-corrected based on the deviation between the exhaust air-fuel ratio detected by the air-fuel ratio sensor and the target air-fuel ratio. An air-fuel ratio feedback control device is known (see Japanese Patent Application Laid-Open No. 6-108901).
[0003]
[Problems to be solved by the invention]
By the way, there is a dead time due to a delay in transportation of combustion exhaust until the result of correcting the fuel injection amount based on the exhaust air / fuel ratio detected by the air / fuel ratio sensor is detected by the air / fuel ratio sensor.
[0004]
Therefore, if feedback control is performed with an excessive gain, a large overshoot is generated, and it is necessary to set a gain that can ensure convergence response while suppressing the overshoot.
[0005]
Therefore, conventionally, an optimum gain is obtained in advance for each intake air amount and rotational speed of the engine that correlates with the dead time, and this is stored in a map, and the gain corresponding to the intake air amount and the rotational speed at that time is set as the gain. Search from the map to perform feedback control.
[0006]
Therefore, conventionally, a man-hour for adapting the gain is required, and a large amount of storage capacity is required for the map for storing the gain for each operating condition. Further, in order to avoid a large overshoot, the response is high. There has been a problem that the air-fuel ratio (A / F) cannot be feedback controlled.
[0007]
The present invention has been made in view of the above problems, eliminates the dead time until the correction result of the fuel injection amount is detected, does not require a gain setting according to the dead time for each operating condition, and An object of the present invention is to provide an air-fuel ratio feedback control device for an internal combustion engine that can correct the air-fuel ratio with high response.
[0008]
[Means for Solving the Problems]
Therefore, in the first aspect of the invention, the air-fuel ratio of the air-fuel mixture formed in the cylinder is estimated, and an air-fuel ratio correction value for correcting the fuel injection amount is calculated based on the estimated in-cylinder air-fuel ratio. On the other hand, an exhaust air-fuel ratio detected by the air-fuel ratio sensor is estimated based on the estimated in-cylinder air-fuel ratio, and based on the estimated exhaust air-fuel ratio and the exhaust air-fuel ratio detected by the air-fuel ratio sensor. , The cylinder air-fuel ratioEstimated value ofTo correctIn the estimation of the air-fuel ratio in the cylinder, the initial air-fuel ratio is calculated based on the air-fuel ratio correction value and the target air-fuel ratio, and the fresh air ratio is calculated based on the volume efficiency, atmospheric pressure, intake pressure, and compression ratio. Calculate the in-cylinder air-fuel ratio based on the initial air-fuel ratio and fresh air ratioConfigured to do.
[0009]
According to this configuration, the cylinder air-fuel ratio is estimated, and the fuel injection amount is feedback-controlled so that the estimated air result coincides with the target air-fuel ratio, while the estimated cylinder air-fuel ratio is delayed and detected by the air-fuel ratio sensor. Based on this, the exhaust air-fuel ratio detected by the air-fuel ratio sensor is estimated, and the estimated error of the cylinder air-fuel ratio is corrected from the estimated value and the exhaust air-fuel ratio actually detected by the air-fuel ratio sensor.Here, based on the air-fuel ratio correction value (air-fuel ratio feedback correction coefficient) and the target air-fuel ratio, an initial air-fuel ratio that is an air-fuel ratio in the calculation of the fuel injection amount is obtained, and further, fresh air that changes with residual gas in the cylinder. The initial air-fuel ratio is corrected by the ratio to estimate the air-fuel ratio of the air-fuel mixture formed by the fresh air and the injected fuel in the cylinder, and the ratio of fresh air that changes with the residual gas in the cylinder is Estimate based on volumetric efficiency, atmospheric pressure, intake pressure, and compression ratio.
  According to the second aspect of the present invention, the air-fuel ratio of the air-fuel mixture formed in the cylinder is estimated, and an air-fuel ratio correction value for correcting the fuel injection amount is calculated based on the estimated in-cylinder air-fuel ratio. On the other hand, the exhaust transport delay time is calculated based on the exhaust pipe volume from the cylinder to the air-fuel ratio sensor and the exhaust gas volume flow rate, and based on the estimated value of the cylinder air-fuel ratio and the exhaust transport delay time, An exhaust air / fuel ratio detected by the air / fuel ratio sensor is estimated, and an estimated value of the in-cylinder air / fuel ratio is corrected based on the estimated exhaust air / fuel ratio and the exhaust air / fuel ratio detected by the air / fuel ratio sensor. did.
  According to this configuration, since it takes time for the combustion gas burned in the cylinder to reach the air-fuel ratio sensor provided in the middle of the exhaust pipe, the estimated value of the in-cylinder air-fuel ratio and the time required for the arrival (transport delay) Assuming that the estimated value of the cylinder air-fuel ratio is detected by the air-fuel ratio sensor after the transport delay time has elapsed, the detected value by the air-fuel ratio sensor is estimated, and the estimated value and the actual air-fuel ratio are actually estimated. The estimation error of the cylinder air-fuel ratio is corrected from the exhaust air-fuel ratio detected by the sensor. Here, the exhaust transportation delay time is obtained as the time required to fill the exhaust pipe volume from the cylinder to the air-fuel ratio sensor with the exhaust.
[0010]
Claim3In the described invention,In the invention of claim 2,The initial air-fuel ratio is calculated based on the air-fuel ratio correction value and the target air-fuel ratio, and the in-cylinder air-fuel ratio is calculated based on the initial air-fuel ratio and the fresh air ratio.
[0011]
According to this configuration, the initial air-fuel ratio, which is the air-fuel ratio in the calculation of the fuel injection amount, is obtained based on the air-fuel ratio correction value (air-fuel ratio feedback correction coefficient) and the target air-fuel ratio, and further varies with the residual gas in the cylinder. The initial air-fuel ratio is corrected with the fresh air ratio, and the air-fuel ratio of the air-fuel mixture formed by fresh air and injected fuel in the cylinder is estimated.
[0012]
Claim4In the described invention,In the invention of claim 3,The new air ratio is calculated based on volumetric efficiency, atmospheric pressure, intake pressure, and compression ratio.
[0013]
According to this configuration, the ratio of fresh air that changes due to residual gas in the cylinder is estimated based on volumetric efficiency, atmospheric pressure, intake pressure, and compression ratio.
[0014]
Claim5In the described invention,In the invention according to any one of claims 1 to 4,Cylinder air-fuel ratioEstimated value ofIs corrected based on the dynamic characteristics of the air-fuel ratio sensor.
[0015]
According to this configuration, the air-fuel ratio in the cylinder is detected by the air-fuel ratio sensor by correcting the air-fuel ratio in the cylinder based on the dynamic characteristic of the air-fuel ratio sensor in which the change in the detected value is delayed with respect to the actual change in the exhaust air-fuel ratio. The detection result in the case of assuming that the air-fuel ratio is assumed is estimated, and feedback control is performed based on the detected value of the air-fuel ratio sensor in the cylinder. That is, it is apparent that the air-fuel ratio in the cylinder is directly detected by the air-fuel ratio sensor and the air-fuel ratio feedback is performed.
[0016]
Claim6In the described invention,In the invention of claim 1,In-cylinder air-fuel ratioEstimated valueAnd the exhaust air / fuel ratio detected by the air / fuel ratio sensor based on the transport delay time of the exhaust.
[0017]
According to such a configuration, since it takes time for the combustion gas burned in the cylinder to reach the air-fuel ratio sensor provided in the middle of the exhaust pipe, the air-fuel ratio in the cylinder and the time required for the arrival (transport delay time) Based on this, the detected value by the air-fuel ratio sensor is estimated on the assumption that the estimated value of the in-cylinder air-fuel ratio is detected by the air-fuel ratio sensor after the transport delay time has elapsed.
[0018]
Claim7In the described invention,In the invention of claim 6,The exhaust transport delay time is calculated based on the exhaust pipe volume from the cylinder to the air-fuel ratio sensor and the exhaust gas volume flow rate.
[0019]
According to such a configuration, the exhaust transportation delay time is obtained as the time required to fill the exhaust pipe volume from the cylinder to the air-fuel ratio sensor with the exhaust gas.
[0020]
Claim8In the described invention,In the invention according to any one of claims 1 to 7,The deviation between the estimated exhaust air-fuel ratio and the exhaust air-fuel ratio detected by the air-fuel ratio sensor is input to a predetermined transfer function, and the cylinder air-fuel ratio is corrected by the output of the transfer function.
[0021]
According to such a configuration, an estimation error when the air-fuel ratio in the air-fuel ratio sensor unit is estimated based on the in-cylinder air-fuel ratio is obtained by comparison with the exhaust air-fuel ratio actually detected by the air-fuel ratio sensor. In order to correct the estimated value of the in-cylinder air-fuel ratio, the air-fuel ratio sensor unit inputs an estimated error into a transfer function and converts it into a correction value for correcting the estimated error of the in-cylinder air-fuel ratio.
[0022]
Meanwhile, claims9The described invention includes an air-fuel ratio sensor for detecting an exhaust air-fuel ratio, an air-fuel ratio correction value for correcting a fuel injection amount, a means for calculating an initial air-fuel ratio based on a target air-fuel ratio at that time, and a fresh air ratio Means for calculating the air-fuel ratio in accordance with the operating conditions, means for calculating the air-fuel ratio in the cylinder based on the initial air-fuel ratio and the fresh air ratio, and correcting the air-fuel ratio in the cylinder according to the dynamic characteristics of the air-fuel ratio sensor. Means for calculating a final estimated air-fuel ratio, means for calculating an exhaust transport delay time to the air-fuel ratio sensor, and exhaust air detected by the air-fuel ratio sensor based on the estimated air-fuel ratio and the exhaust transport delay time. Means for calculating the fuel ratio; means for calculating a disturbance correction value based on the exhaust air / fuel ratio calculated by the means and the exhaust air / fuel ratio detected by the air / fuel ratio sensor; and the target air / fuel ratio, estimated air / fuel ratio and disturbance Air-fuel based on the correction value Means for calculating a correction value, configured to include a means for correcting the fuel injection amount based on the air-fuel ratio correction value.
[0023]
According to this configuration, first, the air-fuel ratio in the calculation of the injection amount is obtained as the initial air-fuel ratio from the air-fuel ratio correction value and the target air-fuel ratio, and the air-fuel mixture formed in the cylinder from the initial air-fuel ratio and the fresh air ratio. Obtain the air-fuel ratio. Further, assuming that the air-fuel ratio of the air-fuel ratio in the cylinder is detected by the air-fuel ratio sensor, the detection result of the air-fuel ratio sensor that is delayed with respect to the change in the air-fuel ratio in the cylinder is estimated, and this is finally determined. Estimated value of cylinder air-fuel ratio.
[0024]
Here, in actuality, the air-fuel ratio sensor is provided not in the cylinder portion but in the middle of the exhaust pipe, and detects the air-fuel ratio in the cylinder with a delay of the exhaust transportation delay time. The air-fuel ratio that should be detected by the air-fuel ratio sensor is estimated assuming that it is detected by the air-fuel ratio sensor with a delay. Then, a disturbance correction value corresponding to the estimation error of the air-fuel ratio is set from the air-fuel ratio estimated as detected by the air-fuel ratio sensor and the air-fuel ratio actually detected by the air-fuel ratio sensor, and the disturbance correction value Then, an air-fuel ratio correction value for correcting the fuel injection amount is calculated from the target air-fuel ratio and the cylinder air-fuel ratio.
  According to a tenth aspect of the present invention, the air-fuel ratio of the air-fuel mixture formed in the cylinder is estimated, and an air-fuel ratio correction value for correcting the fuel injection amount is calculated based on the estimated in-cylinder air-fuel ratio. On the other hand, the estimated in-cylinder air-fuel ratio is corrected according to the dynamic characteristics of the air-fuel ratio sensor, and the exhaust transport delay time to the air-fuel ratio sensor is calculated, and the correction according to the dynamic characteristics is performed. The estimated value of the in-cylinder air-fuel ratio is corrected based on the data before the exhaust transport delay time before the estimated value of the in-cylinder air-fuel ratio and the exhaust air-fuel ratio detected by the air-fuel ratio sensor. .
  According to this configuration, the air-fuel ratio in the cylinder is detected by the air-fuel ratio sensor by correcting the air-fuel ratio in the cylinder based on the dynamic characteristics of the air-fuel ratio sensor in which the change in the detected value is delayed with respect to the actual change in the exhaust air-fuel ratio. The detection result when it is assumed to be made is estimated. Then, the data just before the estimated exhaust transport delay time is the air-fuel ratio that should be detected by the air-fuel ratio sensor, and from this air-fuel ratio and the air-fuel ratio actually detected by the air-fuel ratio sensor, the cylinder air-fuel ratio The estimated value of is corrected.
[0025]
【The invention's effect】
According to the first aspect of the invention, since the air-fuel ratio feedback control is performed by estimating the air-fuel ratio in the cylinder, it is possible to perform the feedback control without a dead time, and the gain for responding to the change in the dead time While adaptation and memory are not required, correction can be performed with high response,It is possible to accurately estimate a fresh air ratio that varies depending on engine operating conditions and environmental conditions, accurately estimate the air-fuel ratio of the air-fuel mixture formed in the cylinder from the fresh air ratio and the air-fuel ratio in fuel injection control, There is an effect that the air-fuel ratio can be controlled with high accuracy by correcting the estimation error of the air-fuel ratio in the cylinder using the air-fuel ratio sensor.
  According to the second aspect of the present invention, the air-fuel ratio to be detected by the air-fuel ratio sensor corresponding to the estimated cylinder air-fuel ratio being detected by the air-fuel ratio sensor after the exhaust transportation delay time has elapsed. Further, there is an effect that the exhaust transport delay time can be accurately estimated based on the exhaust volume flow rate at that time.
[0026]
Claim3According to the described invention, there is an effect that the air-fuel ratio of the air-fuel mixture formed in the cylinder can be accurately estimated from the air-fuel ratio in fuel injection control and the fresh air ratio.
[0027]
Claim4According to the described invention, there is an effect that it is possible to accurately estimate the fresh air ratio that changes depending on the engine operating condition and the environmental condition.
[0028]
Claim5According to the described invention, an estimation result of the air-fuel ratio corresponding to the case where the air-fuel ratio in the cylinder is directly detected by the air-fuel ratio sensor is obtained, and the air-fuel ratio is feedback controlled based on the detection result by the air-fuel ratio sensor. On the other hand, there is an effect that it is possible to construct a control system that eliminates the dead time due to the exhaust transportation delay time.
[0029]
Claim6According to the described invention, the air-fuel ratio to be detected by the air-fuel ratio sensor can be estimated in response to the estimated cylinder air-fuel ratio being detected by the air-fuel ratio sensor after the exhaust transportation delay time has elapsed. There is an effect.
[0030]
Claim7According to the described invention, there is an effect that the transport delay time of the exhaust can be accurately estimated based on the exhaust volume flow rate at that time.
[0031]
Claim8According to the described invention, there is an effect that the estimation error of the in-cylinder air-fuel ratio can be accurately corrected from the estimation error of the air-fuel ratio in the air-fuel ratio sensor unit.
[0032]
Claim9According to the described invention, the detection result when the air-fuel ratio in the cylinder is directly detected by the air-fuel ratio sensor is estimated and the air-fuel ratio is feedback-controlled, so the control is performed with no apparent exhaust transport delay time. This eliminates the need for adapting and storing gains to cope with changes in dead time, and makes it possible to perform correction with high response, while actually causing an error in the estimated value of the in-cylinder air-fuel ratio. There is an effect that it can be accurately corrected from the result detected by the air-fuel ratio sensor, and feedback control can be performed with high accuracy on the target air-fuel ratio.
  According to the tenth aspect of the present invention, the air-fuel ratio to be detected by the air-fuel ratio sensor is estimated corresponding to the dynamic characteristics of the air-fuel ratio sensor and the exhaust transport delay time, and the air-fuel ratio in the cylinder is estimated. There is an effect that the error can be corrected with high accuracy.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0034]
FIG. 1 is a system configuration diagram of an internal combustion engine according to an embodiment.
In FIG. 1, air is sucked into the combustion chamber of each cylinder of an internal combustion engine 1 mounted on a vehicle via an air cleaner 2, an intake passage 3, and an electronically controlled throttle valve 4 that is opened and closed by a motor.
[0035]
An electromagnetic fuel injection valve 5 for directly injecting fuel (gasoline) is provided in the combustion chamber of each cylinder, and the air-fuel mixture is injected into the combustion chamber by the fuel injected from the fuel injection valve 5 and the intake air. Is formed.
[0036]
The fuel injection valve 5 is energized to open a solenoid by an injection pulse signal output from the control unit 20, and injects the fuel adjusted to a predetermined pressure. In the case of intake stroke injection, the injected fuel diffuses into the combustion chamber to form a homogeneous mixture, and in the case of compression stroke injection, a stratified mixture is intensively formed around the spark plug 6. . The air-fuel mixture formed in the combustion chamber is ignited and combusted by the spark plug 6.
[0037]
However, the internal combustion engine 1 is not limited to the direct injection gasoline engine described above, and may be an engine configured to inject fuel into the intake port.
[0038]
Exhaust gas from the engine 1 is discharged from an exhaust passage 7, and an exhaust purification catalyst 8 is interposed in the exhaust passage 7.
[0039]
In addition, an evaporative fuel processing device that combusts evaporative fuel generated in the fuel tank 9 is provided.
[0040]
The canister 10 is a sealed container filled with an adsorbent 11 such as activated carbon, and an evaporative fuel introduction pipe 12 extending from the fuel tank 9 is connected thereto. Therefore, the evaporated fuel generated in the fuel tank 9 passes through the evaporated fuel introduction pipe 12 and is guided to the canister 10 to be adsorbed and collected.
[0041]
In addition, a fresh air inlet 13 is formed in the canister 10 and a purge pipe 14 is led out. A purge control valve 15 whose opening and closing is controlled by a control signal from the control unit 20 is provided in the purge pipe 14. Intervened.
[0042]
In the above configuration, when the purge control valve 15 is controlled to open, the negative suction pressure of the engine 1 acts on the canister 10, so that the air introduced from the fresh air inlet 13 is adsorbed on the adsorbent 11 of the canister 10. The evaporated fuel is purged, and purge air is drawn into the intake passage 3 downstream of the throttle valve 4 through the purge pipe 14, and thereafter, is combusted in the combustion chamber of the engine 1.
[0043]
The control unit 20 includes a microcomputer including a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like, receives input signals from various sensors, performs arithmetic processing based on these signals, and performs fuel processing. The operation of the injection valve 5, spark plug 6 and purge control valve 15 is controlled.
[0044]
As the various sensors, a crank angle sensor 21 that detects the crank angle of the engine 1 and a cam sensor 22 that extracts a cylinder discrimination signal from the cam shaft are provided. Based on the signal from the crank angle sensor 21, the rotational speed Ne of the engine is determined. Calculated.
[0045]
In addition, an air flow meter 23 that detects an intake air flow rate Q (mass flow rate) upstream of the throttle valve 4 in the intake passage 3, an accelerator sensor 24 that detects an accelerator pedal depression amount (accelerator opening) APS, and a throttle valve 4 A throttle sensor 25 for detecting the opening TVO, a water temperature sensor 26 for detecting the cooling water temperature Tw of the engine 1, a wide-range air-fuel ratio sensor 27 for linearly detecting the air-fuel ratio of the combustion mixture according to the oxygen concentration in the exhaust, A vehicle speed sensor 28 for detecting the vehicle speed VSP is provided.
[0046]
Here, the structure of the wide-range air-fuel ratio sensor 27 will be described with reference to FIG. On a substrate 31 made of a solid electrolyte member such as zirconia (ZrO2), a + electrode 32 for measuring oxygen concentration is provided. Further, a hollow portion 33 into which air is introduced is opened in the substrate 31, and a negative electrode 34 is attached to a ceiling portion of the hollow portion 33 so as to face the positive electrode 32 with the substrate 31 interposed therebetween. The substrate 31, the + electrode 32, and the − electrode 34 form an oxygen concentration detector 35.
[0047]
Moreover, it has the oxygen pump part 39 formed by providing the pump electrodes 37 and 38 which consist of a pair of platinum on both surfaces of the solid electrolyte member 36 which consists of zirconia.
[0048]
Then, the oxygen pump unit 39 is stacked above the oxygen concentration detection unit 35 via a spacer 40 formed in a frame shape with alumina, for example, and a hollow chamber is provided between the oxygen concentration detection unit 35 and the oxygen pump unit 39. 41 and an introduction hole 42 for introducing engine exhaust into the hollow chamber 41 is formed in the solid electrolyte member 36 of the oxygen pump section 39.
[0049]
The outer periphery of the spacer 40 is filled with a glass adhesive 43 so as to ensure the sealing of the hollow chamber 41 and to fix the substrate 31 and the spacer 40 and the solid electrolyte 36 together. Here, since the spacer 40 and the substrate 31 are bonded by simultaneous firing, the hermeticity of the hollow chamber 41 is ensured by bonding the spacer 40 and the solid electrolyte member 36. The oxygen concentration detector 39 has a built-in heater 44 for heating.
[0050]
Then, the oxygen concentration of the exhaust gas introduced into the hollow chamber 41 through the introduction hole 42 is detected from the voltage of the positive electrode 32. Specifically, oxygen ions flow in the substrate 31 according to the concentration difference between the oxygen in the atmosphere in the hollow portion 33 and the oxygen in the exhaust in the hollow chamber 41, and accordingly, the exhaust is exhausted to the + electrode 32. An electromotive force corresponding to the oxygen concentration inside is generated.
[0051]
Then, according to the detection result, the current value flowing through the oxygen pump section 39 is controlled so as to keep the atmosphere in the hollow chamber 41 constant (for example, the stoichiometric air-fuel ratio), and the oxygen concentration in the exhaust gas (exhaust gas) is controlled from the current value at that time Air-fuel ratio) is detected.
[0052]
Specifically, the voltage of the positive electrode 32 is amplified by the control circuit 45 and then applied between the electrodes 37 and 38 via the voltage detection resistor 46 so as to keep the oxygen concentration in the hollow chamber 41 constant. To.
[0053]
For example, when detecting the air-fuel ratio in a lean region where the oxygen concentration in the exhaust gas is high, a voltage is applied using the outer pump electrode 37 as an anode and the pump electrode 38 on the hollow chamber 41 side as a cathode. Then, oxygen proportional to the current (oxygen ion O2- ) Is pumped out of the hollow chamber 41. When the applied voltage exceeds a predetermined value, the flowing current reaches a limit value. By measuring the limit current value with the control circuit 45, the oxygen concentration in the exhaust gas, in other words, the exhaust air-fuel ratio can be detected.
[0054]
Conversely, if oxygen is pumped into the hollow chamber 41 with the pump electrode 37 as the cathode and the pump electrode 38 as the anode, the air-fuel ratio can be detected in the air-fuel ratio rich region where the oxygen concentration in the exhaust gas is low.
[0055]
The limit current is detected from the output voltage of the differential amplifier 47 that detects the voltage across the voltage detection resistor 46.
[0056]
The control unit 20 performs air-fuel ratio feedback control according to the present invention so that the air-fuel ratio of the combustion mixture matches the target air-fuel ratio when a predetermined air-fuel ratio feedback control condition is satisfied.
[0057]
The block diagram of FIG. 3 shows the air-fuel ratio feedback control, and the sliding mode controller 51 (air-fuel ratio correction value calculation means) has an estimated air-fuel ratio calculated as described later and a target air-fuel ratio. A deviation (error) is input, and an air-fuel ratio feedback correction coefficient ALPHA (air-fuel ratio correction value) for correcting the fuel injection amount based on the deviation is output.
[0058]
The air-fuel ratio feedback correction coefficient ALPHA is input to a fuel injection amount calculation unit 52 (injection amount correction means), where the basic fuel injection amount is corrected by the air-fuel ratio feedback correction coefficient ALPHA to obtain the final fuel injection amount. Ti is calculated, and an injection pulse signal having a pulse width corresponding to the fuel injection amount Ti is output to the fuel injection valve 5 of the engine 1.
[0059]
FIG. 4 is a block diagram showing details of the sliding mode controller 51. The linear term calculation unit 511 calculates a linear term U1 based on the deviation (error), and a nonlinear term U2 based on the deviation (error). It comprises a non-linear term calculation unit 512 for calculating, and outputs an air-fuel ratio feedback correction coefficient ALPHA as linear term U1 + nonlinear term U2 = ALPHA.
[0060]
The linear term calculation unit 511 calculates error x gain, ∫ (error) x gain, and target air-fuel ratio x gain, and calculates the linear term U1 by summing up these calculation results. If the error is x1 and αi, ai, b (i: 1,2,3) are coefficients,
U1 = 1 / b ((a0−α3−α1 (a1−α1)) x1−α3 (a1−α1) ∫ (x1) + a0r)
As a result, the linear term U1 is calculated.
[0061]
On the other hand, the nonlinear term calculation unit 512 has a switching function σ, a chattering prevention coefficient δ, and a coefficient K,
σ = α1 · x1 + d (x1) / dt + α3∫ (x1)
U2 = K · σ / (| σ | + δ)
As a result, the nonlinear term U2 is calculated.
[0062]
In this embodiment, the air-fuel ratio feedback correction coefficient ALPHA is calculated from the deviation (error) by the sliding mode. However, the air-fuel ratio feedback correction coefficient is calculated by the proportional integral operation (PI) or the proportional integral derivative operation (PID). It is good also as a structure which calculates ALPHA.
[0063]
For example, when the air-fuel ratio feedback correction coefficient ALPHA is calculated by proportional integral derivative operation (PID), when the proportional gain is Kp, the integral gain is Ki, and the differential gain is Kd,
ALPHA = Kp · x1 + Ki · ∫ (x1) + Kd · d (x1) / dt
As a result, an air-fuel ratio feedback correction coefficient ALPHA is calculated.
[0064]
Further, the configuration may be such that the air-fuel ratio feedback correction coefficient ALPHA is calculated in a sliding mode having a configuration different from that shown in FIG. 4, and the air-fuel ratio feedback correction coefficient ALPHA is calculated so as to bring the estimated air-fuel ratio closer to the target air-fuel ratio. Any known configuration can be applied.
[0065]
On the other hand, an air-fuel ratio estimating unit 53, an after-dead-time air-fuel ratio estimating unit 54, and a disturbance compensator 55 are provided as components for calculating an estimated air-fuel ratio used for calculating the air-fuel ratio deviation (error).
[0066]
FIG. 5 shows details of the air-fuel ratio estimation unit 53. The air-fuel ratio feedback correction coefficient ALPHA and the target equivalent ratio TFBYA are input to the initial air-fuel ratio calculation unit 531 (initial air-fuel ratio calculation means). The initial air / fuel ratio is
Initial air-fuel ratio = coefficient / (ALPHA × TFBYA)
Calculate as
[0067]
Since the fuel injection amount is calculated as the injection amount equivalent to the theoretical air-fuel ratio × TFBYA × ALPHA, ALPHA × TFBYA is an equivalent ratio in the calculation of the fuel injection amount, and the reciprocal of this equivalent ratio is multiplied by a coefficient. The air-fuel ratio is converted.
[0068]
The initial air-fuel ratio is input to an in-cylinder air-fuel ratio calculation unit 532 (in-cylinder air-fuel ratio calculation means). The in-cylinder air-fuel ratio calculation unit 532 calculates the inside air amount from the fresh air ratio η and the initial air-fuel ratio. The air-fuel ratio is calculated according to the following formula.
[0069]
In-cylinder air / fuel ratio = η × initial air / fuel ratio + (1−η) × in-cylinder air / fuel ratio (old) The fresh air ratio η is calculated by a fresh air ratio calculation unit 533 (fresh air ratio calculation means).
[0070]
The fresh air ratio calculation unit 533 receives the engine speed Ne, the intake air flow rate detected by the air flow meter 23, the atmospheric pressure, and the intake pressure, and calculates the fresh air ratio η according to the following equation.
[0071]
η = ηv × (atmospheric pressure / intake pressure) × ((ε−1) / ε)
Here, ηv is volumetric efficiency and is set based on the engine rotational speed Ne and the intake air flow rate. Further, ε is a compression ratio.
[0072]
The atmospheric pressure and the intake pressure may be provided with a sensor for detecting each of them, or may be estimated from operating conditions.
[0073]
The in-cylinder air-fuel ratio calculated by the in-cylinder air-fuel ratio calculation unit 532 is input to the primary delay correction unit 534.
[0074]
When the air-fuel ratio sensor 27 detects the in-cylinder air-fuel ratio, in other words, the primary delay correction unit 534 detects the air-fuel ratio sensor 27 when it is assumed that the air-fuel ratio sensor 27 is installed in the cylinder. The air-fuel ratio is estimated.
[0075]
Since the air-fuel ratio sensor 27 has a dynamic characteristic that responds to a change in oxygen concentration (air-fuel ratio) with a first-order lag, the first-order lag correction unit 534 (estimated air-fuel ratio calculation means) The first-order lag correction is applied to this, and this is estimated as a detection result when the air-fuel ratio sensor 27 detects the in-cylinder air-fuel ratio.
[0076]
Specifically, when the estimated value of the air-fuel ratio detected by the air-fuel ratio sensor 27 is the estimated air-fuel ratio,
Figure 0003869634
The estimated air-fuel ratio is calculated as follows.
[0077]
The estimated air-fuel ratio calculated by the primary delay correction unit 534 estimates the air-fuel ratio under the condition that there is no exhaust transport delay (dead time), and air-fuel ratio feedback control (sliding) based on the estimated air-fuel ratio. If the configuration is such that the calculation of the correction coefficient ALPHA in the mode controller 51 is performed, it is not necessary to adapt and store the gain to cope with the change in dead time, and correction can be performed with high response.
[0078]
However, since the estimated air-fuel ratio deviates from the actual air-fuel ratio due to the influence of disturbance, the estimated air-fuel ratio is corrected using the air-fuel ratio sensor 27. Specifically, the dead time The correction is performed by the rear air-fuel ratio estimation unit 54 and the disturbance compensator 55.
[0079]
As shown in FIG. 6, the post-dead-time air-fuel ratio estimation unit 54 includes an exhaust transport delay time calculation unit 541 and an after-exhaust transport delay air-fuel ratio calculation unit 542.
[0080]
The exhaust transport delay time calculation unit 541 (transport delay time calculating means) calculates the exhaust transport delay time from the exhaust pipe volume from the cylinder to the air-fuel ratio sensor 27 and the exhaust gas volume flow rate.
Exhaust transport delay time = exhaust pipe volume / exhaust gas volume flow rate
Calculate as
[0081]
Here, since the exhaust pipe volume is a fixed value, it is stored in advance. Further, regarding the exhaust gas volume flow rate, the mass flow rate of intake air detected by the air flow meter 23 is regarded as the exhaust gas mass flow rate, and the volume flow rate is calculated from the exhaust gas mass flow rate and the exhaust temperature.
[0082]
The post-exhaust air delay calculating unit 542 (exhaust air / fuel ratio calculating means) stores the estimated air / fuel ratio calculated by the primary delay correcting unit 534 in the past predetermined time in time series and stored in this time series. From the plurality of estimated air-fuel ratio data, the data preceding by the exhaust transport delay time is retrieved and output as the air-fuel ratio after exhaust transport delay (exhaust air-fuel ratio).
[0083]
That is, the estimated air-fuel ratio calculated by the primary delay correction unit 534 is the in-cylinder air-fuel ratio, and the air-fuel ratio exhaust reaches the air-fuel ratio sensor 27 after the exhaust transport delay time elapses. Thus, the exhaust air-fuel ratio that is detected by the air-fuel ratio sensor 27 at this time is the in-cylinder air-fuel ratio that is the previous exhaust transport delay time.
[0084]
The air-fuel ratio after the exhaust transportation delay is input to a disturbance compensator 55 (disturbance correction value calculation means) together with the air-fuel ratio detected by the air-fuel ratio sensor 27. In the disturbance compensator 55, the air-fuel ratio detected by the air-fuel ratio sensor 27 The deviation from the air-fuel ratio after delay in exhaust transportation (estimated exhaust air-fuel ratio) is input to a preset transfer function, and the output is output as a correction value (disturbance correction value) of the estimated air-fuel ratio.
[0085]
The deviation between the air-fuel ratio detected by the air-fuel ratio sensor 27 and the air-fuel ratio after the exhaust transport delay indicates an error in the air-fuel ratio after the exhaust transport delay, but it is necessary to correct the estimated air-fuel ratio that is the in-cylinder air-fuel ratio. Therefore, the transfer function is system-identified in advance so that the estimated air-fuel ratio, which is the cylinder air-fuel ratio, is appropriately corrected from the deviation.
[0086]
The output of the disturbance compensator 55 is added to the estimated air-fuel ratio output from the first-order lag correction unit 534, and the air-fuel ratio feedback is based on the deviation between the estimated air-fuel ratio corrected by the addition and the target air-fuel ratio. The correction coefficient ALPHA is calculated. Therefore, it is possible to prevent a large error from occurring in the estimated air-fuel ratio due to disturbance, and to perform feedback control to the target air-fuel ratio with high accuracy.
[0087]
In this embodiment, the estimated air-fuel ratio is corrected with the output of the disturbance compensator 55 and then the deviation from the target air-fuel ratio is obtained. For example, the target air-fuel ratio is corrected with the output of the disturbance compensator 55. However, even if the deviation between the corrected target air-fuel ratio and the estimated air-fuel ratio is calculated, there is no substantial difference.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of an internal combustion engine in an embodiment.
FIG. 2 is a diagram showing an air-fuel ratio sensor and its peripheral circuits in the embodiment.
FIG. 3 is a block diagram showing a configuration of air-fuel ratio feedback control in the embodiment.
FIG. 4 is a block diagram showing a sliding mode controller in the embodiment.
FIG. 5 is a block diagram showing an air-fuel ratio estimation unit in the embodiment.
FIG. 6 is a block diagram showing a post-dead-time air-fuel ratio estimation unit in the embodiment.
[Explanation of symbols]
1. Internal combustion engine
3 ... Intake passage
4 ... Throttle valve
5 ... Fuel injection valve
20 ... Control unit
27 ... Air-fuel ratio sensor
51 ... Sliding mode controller
52 ... Fuel injection amount calculation section
53. Air-fuel ratio estimation unit
54 ... Air-fuel ratio estimation unit after dead time
55 ... Disturbance compensator

Claims (10)

排気空燃比を検出する空燃比センサを備えた内燃機関の空燃比フィードバック制御装置であって、
シリンダ内に形成される混合気の空燃比を推定し、
該推定したシリンダ内空燃比に基づいて燃料噴射量を補正するための空燃比補正値を演算するよう構成する一方、
前記推定したシリンダ内空燃比に基づき前記空燃比センサで検出される排気空燃比を推定し、
該推定した排気空燃比と前記空燃比センサで検出された排気空燃比に基づいて、前記シリンダ内空燃比の推定値を補正するよう構成される共に、
前記シリンダ内空燃比の推定において、前記空燃比補正値及び目標空燃比に基づき初期空燃比を演算し、体積効率，大気圧，吸気圧，圧縮比に基づいて新気割合を演算し、前記初期空燃比と新気割合とに基づいてシリンダ内空燃比を演算することを特徴とする内燃機関の空燃比フィードバック制御装置。An air-fuel ratio feedback control device for an internal combustion engine provided with an air-fuel ratio sensor for detecting an exhaust air-fuel ratio,
Estimating the air-fuel ratio of the air-fuel mixture formed in the cylinder,
While configured to calculate an air-fuel ratio correction value for correcting the fuel injection amount based on the estimated in-cylinder air-fuel ratio,
Estimating an exhaust air-fuel ratio detected by the air-fuel ratio sensor based on the estimated in-cylinder air-fuel ratio,
Based on the estimated exhaust air / fuel ratio and the exhaust air / fuel ratio detected by the air / fuel ratio sensor, the estimated value of the in-cylinder air / fuel ratio is corrected ,
In the estimation of the in-cylinder air-fuel ratio, an initial air-fuel ratio is calculated based on the air-fuel ratio correction value and the target air-fuel ratio, a fresh air ratio is calculated based on volume efficiency, atmospheric pressure, intake pressure, and compression ratio, and the initial air-fuel ratio is calculated. An air-fuel ratio feedback control apparatus for an internal combustion engine, wherein an air-fuel ratio in a cylinder is calculated based on an air-fuel ratio and a fresh air ratio . 排気空燃比を検出する空燃比センサを備えた内燃機関の空燃比フィードバック制御装置であって、
シリンダ内に形成される混合気の空燃比を推定し、該推定したシリンダ内空燃比に基づいて燃料噴射量を補正するための空燃比補正値を演算するよう構成する一方、
排気の輸送遅れ時間を、シリンダから前記空燃比センサまでの排気配管体積及び排気ガスの体積流量に基づき演算し、前記シリンダ内空燃比の推定値と前記排気の輸送遅れ時間に基づき、前記空燃比センサで検出される排気空燃比を推定し、該推定した排気空燃比と前記空燃比センサで検出された排気空燃比に基づいて、前記シリンダ内空燃比の推定値を補正するよう構成されたことを特徴とする内燃機関の空燃比フィードバック制御装置。 An air-fuel ratio feedback control device for an internal combustion engine provided with an air-fuel ratio sensor for detecting an exhaust air-fuel ratio,
While estimating the air-fuel ratio of the air-fuel mixture formed in the cylinder and calculating the air-fuel ratio correction value for correcting the fuel injection amount based on the estimated in-cylinder air-fuel ratio,
An exhaust transport delay time is calculated based on an exhaust pipe volume from the cylinder to the air-fuel ratio sensor and an exhaust gas volume flow rate, and the air-fuel ratio is calculated based on the estimated value of the in-cylinder air-fuel ratio and the exhaust transport delay time. An exhaust air / fuel ratio detected by a sensor is estimated, and an estimated value of the in-cylinder air / fuel ratio is corrected based on the estimated exhaust air / fuel ratio and the exhaust air / fuel ratio detected by the air / fuel ratio sensor. An air-fuel ratio feedback control device for an internal combustion engine , characterized by: 前記空燃比補正値及び目標空燃比に基づき初期空燃比を演算し、該初期空燃比と新気割合とに基づいてシリンダ内空燃比を演算することを特徴とする請求項２記載の内燃機関の空燃比フィードバック制御装置。 3. The internal combustion engine according to claim 2, wherein an initial air-fuel ratio is calculated based on the air-fuel ratio correction value and the target air-fuel ratio, and an in-cylinder air-fuel ratio is calculated based on the initial air-fuel ratio and a fresh air ratio. Air-fuel ratio feedback control device. 前記新気割合を、体積効率，大気圧，吸気圧，圧縮比に基づいて演算することを特徴とする請求項３記載の内燃機関の空燃比フィードバック制御装置。4. The air-fuel ratio feedback control apparatus for an internal combustion engine according to claim 3 , wherein the fresh air ratio is calculated based on volumetric efficiency, atmospheric pressure, intake pressure, and compression ratio. 前記シリンダ内空燃比の推定値を、前記空燃比センサの動特性に基づき補正することを特徴とする請求項１〜４のいずれか１つに記載の内燃機関の空燃比フィードバック制御装置。The air-fuel ratio feedback control apparatus for an internal combustion engine according to any one of claims 1 to 4 , wherein the estimated value of the in-cylinder air-fuel ratio is corrected based on dynamic characteristics of the air-fuel ratio sensor. 前記シリンダ内空燃比の推定値と排気の輸送遅れ時間に基づき、前記空燃比センサで検出される排気空燃比を推定することを特徴とする請求項１記載の内燃機関の空燃比フィードバック制御装置。Based on the estimated value of the cylinder air-fuel ratio and transport delay time of the exhaust air-fuel ratio feedback control apparatus for an internal combustion engine according to claim 1, wherein the estimating the exhaust air-fuel ratio detected by the air-fuel ratio sensor. 前記排気の輸送遅れ時間を、シリンダから前記空燃比センサまでの排気配管体積及び排気ガスの体積流量に基づき演算することを特徴とする請求項６記載の内燃機関の空燃比フィードバック制御装置。  The air-fuel ratio feedback control apparatus for an internal combustion engine according to claim 6, wherein the exhaust transport delay time is calculated based on an exhaust pipe volume from a cylinder to the air-fuel ratio sensor and an exhaust gas volume flow rate. 前記推定した排気空燃比と前記空燃比センサで検出された排気空燃比との偏差を、所定の伝達関数に入力し、該伝達関数の出力で前記シリンダ内空燃比の推定値を補正することを特徴とする請求項１〜７のいずれか１つに記載の内燃機関の空燃比フィードバック制御装置。The deviation between the estimated exhaust air / fuel ratio and the exhaust air / fuel ratio detected by the air / fuel ratio sensor is input to a predetermined transfer function, and the estimated value of the in-cylinder air / fuel ratio is corrected by the output of the transfer function. The air-fuel ratio feedback control device for an internal combustion engine according to any one of claims 1 to 7 . 排気空燃比を検出する空燃比センサと、
燃料噴射量を補正するための空燃比補正値と目標空燃比に基づいて初期空燃比を演算する初期空燃比演算手段と、
新気割合を運転条件に応じて演算する新気割合演算手段と、
前記初期空燃比と新気割合に基づいてシリンダ内空燃比を演算するシリンダ内空燃比演算手段と、
前記シリンダ内空燃比に前記空燃比センサの動特性に応じた補正を施して最終的な推定空燃比を演算する推定空燃比演算手段と、
前記空燃比センサまでの排気輸送遅れ時間を演算する輸送遅れ時間演算手段と、
前記推定空燃比と前記排気輸送遅れ時間に基づいて前記空燃比センサで検出される排気空燃比を演算する排気空燃比演算手段と、
該排気空燃比演算手段で演算された排気空燃比と前記空燃比センサで検出された排気空燃比に基づいて外乱補正値を演算する外乱補正値演算手段と、
前記目標空燃比，推定空燃比及び外乱補正値に基づいて前記空燃比補正値を演算する空燃比補正値演算手段と、
前記空燃比補正値に基づいて燃料噴射量を補正する噴射量補正手段と、
を含んで構成されたことを特徴とする内燃機関の空燃比フィードバック制御装置。An air-fuel ratio sensor for detecting the exhaust air-fuel ratio;
An initial air-fuel ratio calculating means for calculating an initial air-fuel ratio based on an air-fuel ratio correction value for correcting the fuel injection amount and a target air-fuel ratio;
A fresh air ratio calculating means for calculating a fresh air ratio according to operating conditions;
An in-cylinder air-fuel ratio calculating means for calculating an in-cylinder air-fuel ratio based on the initial air-fuel ratio and the fresh air ratio;
Estimated air-fuel ratio calculating means for correcting the in-cylinder air-fuel ratio according to the dynamic characteristics of the air-fuel ratio sensor and calculating a final estimated air-fuel ratio;
Transport delay time calculating means for calculating exhaust transport delay time to the air-fuel ratio sensor;
Exhaust air-fuel ratio calculating means for calculating an exhaust air-fuel ratio detected by the air-fuel ratio sensor based on the estimated air-fuel ratio and the exhaust transport delay time;
Disturbance correction value calculating means for calculating a disturbance correction value based on the exhaust air / fuel ratio calculated by the exhaust air / fuel ratio calculating means and the exhaust air / fuel ratio detected by the air / fuel ratio sensor;
Air-fuel ratio correction value calculating means for calculating the air-fuel ratio correction value based on the target air-fuel ratio, the estimated air-fuel ratio, and a disturbance correction value;
Injection amount correction means for correcting the fuel injection amount based on the air-fuel ratio correction value;
An air-fuel ratio feedback control device for an internal combustion engine, characterized by comprising: 排気空燃比を検出する空燃比センサを備えた内燃機関の空燃比フィードバック制御装置であって、An air-fuel ratio feedback control device for an internal combustion engine provided with an air-fuel ratio sensor for detecting an exhaust air-fuel ratio,
シリンダ内に形成される混合気の空燃比を推定し、該推定したシリンダ内空燃比に基づいて燃料噴射量を補正するための空燃比補正値を演算するよう構成する一方、While estimating the air-fuel ratio of the air-fuel mixture formed in the cylinder and calculating the air-fuel ratio correction value for correcting the fuel injection amount based on the estimated in-cylinder air-fuel ratio,
前記推定したシリンダ内空燃比に前記空燃比センサの動特性に応じた補正を施すと共に、前記空燃比センサまでの排気輸送遅れ時間を演算し、前記動特性に応じた補正が施されたシリンダ内空燃比の推定値の前記排気輸送遅れ時間だけ前のデータと、前記空燃比センサで検出された排気空燃比とに基づいて、前記シリンダ内空燃比の推定値を補正するよう構成されたことを特徴とする内燃機関の空燃比フィードバック制御装置。A correction is made to the estimated in-cylinder air-fuel ratio according to the dynamic characteristics of the air-fuel ratio sensor, an exhaust transport delay time to the air-fuel ratio sensor is calculated, and the cylinder inside the cylinder subjected to the correction according to the dynamic characteristics is calculated. The estimated value of the in-cylinder air-fuel ratio is corrected based on the data before the exhaust transport delay time of the estimated value of the air-fuel ratio and the exhaust air-fuel ratio detected by the air-fuel ratio sensor. An air-fuel ratio feedback control device for an internal combustion engine characterized by the above.
JP2000214174A 2000-07-07 2000-07-14 Air-fuel ratio feedback control device for internal combustion engine Expired - Fee Related JP3869634B2 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2000214174A JP3869634B2 (en) 2000-07-14 2000-07-14 Air-fuel ratio feedback control device for internal combustion engine
US09/897,925 US6708681B2 (en) 2000-07-07 2001-07-05 Method and device for feedback controlling air-fuel ratio of internal combustion engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2000214174A JP3869634B2 (en) 2000-07-14 2000-07-14 Air-fuel ratio feedback control device for internal combustion engine

Publications (2)

Publication Number Publication Date
JP2002030968A JP2002030968A (en) 2002-01-31
JP3869634B2 true JP3869634B2 (en) 2007-01-17

Family

ID=18709800

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2000214174A Expired - Fee Related JP3869634B2 (en) 2000-07-07 2000-07-14 Air-fuel ratio feedback control device for internal combustion engine

Country Status (1)

Country Link
JP (1) JP3869634B2 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4536572B2 (en) * 2005-04-06 2010-09-01 本田技研工業株式会社 Air-fuel ratio estimation device for internal combustion engine
JP4985577B2 (en) * 2008-07-24 2012-07-25 トヨタ自動車株式会社 Air-fuel ratio sensor abnormality diagnosis device
JP6879460B2 (en) * 2017-03-30 2021-06-02 三菱自動車工業株式会社 Engine control

Also Published As

Publication number Publication date
JP2002030968A (en) 2002-01-31

Similar Documents

Publication Publication Date Title
US6453229B1 (en) Air-fuel ratio control device for internal combustion engine and method thereof
JP3850620B2 (en) Air-fuel ratio feedback control device for internal combustion engine
US6708681B2 (en) Method and device for feedback controlling air-fuel ratio of internal combustion engine
JPH01313644A (en) Oxygen concentration detector for internal combustion engine controller
US5977525A (en) Control device for a heater for an air fuel ratio sensor in an intake passage
JPH1162729A (en) Evaporated fuel treating device for internal combustion engine
JP3842528B2 (en) Air-fuel ratio feedback control device for internal combustion engine
JPH0612525Y2 (en) Air-fuel ratio detector
JP3869634B2 (en) Air-fuel ratio feedback control device for internal combustion engine
JP4449793B2 (en) Air flow meter abnormality detection device and engine control device
JP2002309993A (en) Control device for internal combustion engine
JP3816293B2 (en) Air-fuel ratio feedback control device for internal combustion engine
JPH0461180B2 (en)
JPH09177618A (en) Evaporated fuel control device for internal combustion engine
JPH0514551U (en) Evaporative fuel control device for internal combustion engine
JP2002364427A (en) Air-fuel ratio controller for engine
CN106574890A (en) Internal combustion engine
JP3751507B2 (en) Air-fuel ratio sensor activity determination device
US6453895B2 (en) Feedback control device and feedback control method of air-fuel ratio in internal combustion engine
JP2002030964A (en) Air-fuel ratio feedback control device for internal combustion engine
JP2001329893A (en) Air-fuel ratio feedback control device for internal combustion engine
JPH0615843B2 (en) Control device for internal combustion engine
JPH0615845B2 (en) Control device for internal combustion engine
JP2002364423A (en) Air-fuel ratio controller for engine
JP2001263125A (en) Air-fuel ratio feedback control device for internal combustion engine

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20031224

A711 Notification of change in applicant

Free format text: JAPANESE INTERMEDIATE CODE: A712

Effective date: 20041217

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20060202

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20060711

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20060904

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20060926

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20061013

R150 Certificate of patent or registration of utility model

Free format text: JAPANESE INTERMEDIATE CODE: R150

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20101020

Year of fee payment: 4

S111 Request for change of ownership or part of ownership

Free format text: JAPANESE INTERMEDIATE CODE: R313111

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20101020

Year of fee payment: 4

R350 Written notification of registration of transfer

Free format text: JAPANESE INTERMEDIATE CODE: R350

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20111020

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20121020

Year of fee payment: 6

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20131020

Year of fee payment: 7

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20131020

Year of fee payment: 7

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20141020

Year of fee payment: 8

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

LAPS Cancellation because of no payment of annual fees