JP3711939B2 - Control device for spark ignition engine - Google Patents

Control device for spark ignition engine Download PDF

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Publication number
JP3711939B2
JP3711939B2 JP2002024548A JP2002024548A JP3711939B2 JP 3711939 B2 JP3711939 B2 JP 3711939B2 JP 2002024548 A JP2002024548 A JP 2002024548A JP 2002024548 A JP2002024548 A JP 2002024548A JP 3711939 B2 JP3711939 B2 JP 3711939B2
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Japan
Prior art keywords
cylinder
exhaust
intake
fuel
fuel ratio
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Expired - Fee Related
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JP2002024548A
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Japanese (ja)
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JP2003227383A (en
Inventor
光夫 人見
武俊 山内
義之 進矢
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Mazda Motor Corp
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Mazda Motor Corp
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Priority to JP2002024548A priority Critical patent/JP3711939B2/en
Application filed by Mazda Motor Corp filed Critical Mazda Motor Corp
Priority to CNB03802487XA priority patent/CN100368671C/en
Priority to US10/472,523 priority patent/US7182050B2/en
Priority to US10/472,563 priority patent/US7219634B2/en
Priority to DE60300437T priority patent/DE60300437T2/en
Priority to EP03703109A priority patent/EP1362176B1/en
Priority to EP03703108A priority patent/EP1366279B1/en
Priority to CNB038024594A priority patent/CN100363609C/en
Priority to PCT/JP2003/000962 priority patent/WO2003064838A1/en
Priority to KR10-2003-7014141A priority patent/KR20040074591A/en
Priority to KR10-2003-7014146A priority patent/KR20040074592A/en
Priority to DE60309098T priority patent/DE60309098T8/en
Priority to PCT/JP2003/000961 priority patent/WO2003064837A1/en
Publication of JP2003227383A publication Critical patent/JP2003227383A/en
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Publication of JP3711939B2 publication Critical patent/JP3711939B2/en
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    • Y02T10/125—
    • Y02T10/144—

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  • Exhaust-Gas Circulating Devices (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、火花点火式エンジンの制御装置に関し、より詳しくは、多気筒エンジンにおいて燃費改善及びエミッション向上のために各気筒の燃焼状態を制御する装置に関するものである。
【０００２】
【従来の技術】
従来から、火花点火式エンジンにおいて、各気筒内の混合気の空燃比を理論空燃比よりも大きいリーン空燃比とした状態で燃焼を行わせることにより燃費改善を図る技術が知られており、例えば特開平１０−２７４０８５号公報に示されるように、燃焼室内に直接燃料を噴射する燃料噴射弁を備え、低回転低負荷域等では上記燃料噴射弁から圧縮行程で燃料を噴射することにより成層燃焼を行わせ、これによって超リーン燃焼を実現するようにしたものが知られている。
【０００３】
このようなエンジンにおいては、排気ガス浄化用の触媒として通常の三元触媒（ＨＣ，ＣＯ及びＮＯｘに対して理論空燃比付近で浄化性能の高い触媒）だけではリーン運転時にＮＯｘに対して充分な浄化性能が得られないため、上記公報にも示されるように、酸素過剰雰囲気でＮＯｘを吸着して酸素濃度低下雰囲気でＮＯｘの離脱、還元を行うリーンＮＯｘ触媒を設けている。そして、このようなリーンＮＯｘ触媒を用いる場合、リーン運転中にリーンＮＯｘ触媒のＮＯｘ吸着量が増大したときは、例えば上記公報に示されるように主燃焼以外に膨張行程中に追加燃料を噴射することで排気ガスの空燃比をリッチ化するとともにＣＯを生成し、これによってＮＯｘの離脱、還元を促進するようにしている。
【０００４】
【発明が解決しようとする課題】
上記のような従来のリーン運転を行うエンジンでは、リーン運転中のＮＯｘ浄化性能の確保のために上記リーンＮＯｘ触媒を必要とする。そして、高負荷域等の理論空燃比で運転される領域での排気浄化のために三元触媒も必要であって、この三元触媒に加えて上記リーンＮＯｘ触媒が設けられ、かつ、このリーンＮＯｘ触媒はＮＯｘ吸着量をある程度確保するために比較的大容量が必要となり、また、三元触媒と比べて高価であるため、コスト的に不利である。
【０００５】
しかも、上記リーンＮＯｘ触媒の浄化性能を維持するためには、上述のようにＮＯｘ吸着量が増大するような所定の期間毎に、ＮＯｘの離脱、還元のため追加燃料の供給等による一時的な空燃比のリッチ化を行う必要があり、これにより、リーン燃焼による燃費改善効果が目減りしてしまうことになる。
【０００６】
さらに、使用燃料が硫黄分を多く含む場合、上記リーンＮＯｘ触媒は硫黄被毒を受け易く、この硫黄被毒の解消のために触媒の加熱及び還元材供給等のリジェネレーション処理が必要となり、これによって燃費改善効果の低減及び耐久性の低下等を招くおそれがある。
【０００７】
本発明は以上のような従来の課題を考慮してなされたものであり、リーン燃焼による燃費改善効果をもたせつつ、リーンＮＯｘ触媒を必要とせず三元触媒を用いるだけで、排気浄化性能を向上することすることができる火花点火式エンジンの制御装置を提供するものである。
【０００８】
【課題を解決するための手段】
請求項１に係る発明は、各気筒が所定の位相差をもって吸気、圧縮、膨張、排気の各行程からなるサイクルを行うようになっている多気筒の火花点火式エンジンにおいて、少なくとも低負荷低回転域で、排気行程と吸気行程が重なる一対の気筒間において排気行程側の気筒である先行気筒から排出される既燃ガスがそのまま吸気行程側の気筒である後続気筒に気筒間ガス通路を介して導入され、この後続気筒から排出されるガスのみが三元触媒を備えた排気通路に導かれるような２気筒接続状態にガス流通経路を構成するとともに、上記２気筒接続状態にあるときに、上記先行気筒では理論空燃比よりも所定量大きいリーン空燃比とした状態で燃焼を行わせ、上記後続気筒では、先行気筒から導入されたリーン空燃比の既燃ガスに燃料を供給して理論空燃比とした状態で燃焼を行わせるように、各気筒に対する燃料供給を制御する制御手段を備えたものである。
【０００９】
この構成によると、少なくとも低負荷低回転域において、上記先行気筒ではリーン空燃比での燃焼が行われて、熱効率が高められるとともにポンピングロスが低減されることにより大幅な燃費改善効果が得られ、また、上記後続気筒では先行気筒から導入されたリーン空燃比の既燃ガスに燃料が供給されて理論空燃比とされた状態で燃焼が行われて、少なくともポンピングロス低減による燃費効果は得られる。しかも、後続気筒から排出される理論空燃比の既燃ガスのみが三元触媒を備えた排気通路に導かれるため、三元触媒だけで充分に排気浄化性能が確保され、リーンＮＯｘ触媒が不要となる。
【００１０】
また、先行気筒ではリーン空燃比で燃焼が行われることによりＮＯｘ発生量が比較的少なく抑えられ、後続気筒では、先行気筒から既燃ガスが導入されることで多量のＥＧＲが行われているのと同等の状態となることからＮＯｘの発生が充分に抑制され、この面からもエミッションの向上に有利となる。
【００１１】
また、先行気筒から排出された高温のガスは気筒間ガス通路を通る間に適度に放熱されて温度調整され、かつ、このガス中の過剰空気と既燃ガスが均一に分散するようにミキシングされた状態で後続気筒に導入されることにより、多量ＥＧＲに対しては理想的な状態となる。さらに、比較的高温のガス中に燃料が噴射されるため、燃料の気化が促進されることもあり、後続気筒において燃焼が良好に行われる。
【００１２】
請求項２に係る発明は、請求項１記載の装置において、排気行程と吸気行程とが完全に重なり合う２つの気筒、または一方の気筒の排気行程が他方の気筒の吸気行程より先行するとともに両行程が部分的に重なり合う２つの気筒を先行、後続の一対の気筒としたものである。
【００１３】
このようにすると、排気行程の先行気筒から排出された既燃ガスが気筒間ガス通路を通って吸気行程の後続気筒にスムーズに導入され、効果的にポンピングロスが低減される。
【００１４】
請求項３に係る発明は、請求項１または２記載の装置において、上記２気筒接続状態にあるときの先行気筒の空燃比を理論空燃比の略２倍もしくはそれ以上としたものである。
【００１５】
このようにすると、先行気筒でのリーン燃焼による燃費改善効果が充分に高められるとともに、後続気筒に導入される既燃ガス中の過剰空気が少なくなりすぎることが避けられて、後続気筒での燃焼性が確保される。
【００１６】
請求項４に係る発明は、請求項１乃至３のいずれかに記載の装置において、高負荷、高回転側の運転領域では各気筒の吸気ポートと排気ポートとを独立させて、吸気通路から各気筒の吸気ポートに新気を導入するとともに各気筒の排気ポートから排出される排気ガスを上記排気通路に導くように新気及びガスの流通経路を切換える流通経路切換手段を備え、上記制御手段は上記高負荷、高回転側の運転領域で各気筒の空燃比を理論空燃比もしくはそれ以下とするようにしたものである。
【００１７】
このようにすると、低負荷低回転域で燃費およびエミッションの改善が図られる一方、高負荷、高回転側の運転領域で出力性能が確保される。
【００１８】
請求項５に係る発明は、請求項４に記載の装置において、上記先行気筒に、上記吸気通路に通じる吸気ポートと、上記排気通路に通じる第１排気ポートと、気筒間ガス通路に通じる第２排気ポートとを設ける一方、上記後続気筒に、上記吸気通路に通じる第１吸気ポートと、上記気筒間ガス通路に通じる第２吸気ポートと、上記排気通路に通じる排気ポートとを設け、上記流通経路切換手段として、上記先行気筒の第１，第２排気ポートを開閉する第１，第２排気弁および後続気筒の第１，第２吸気ポートを開閉する第１，第２吸気弁をそれぞれ作動状態と停止状態とに切換える弁停止機構と、低負荷低回転域では上記第１排気弁および上記第１吸気弁を停止状態、上記第２排気弁および上記第２吸気弁を作動状態とし、高負荷、高回転側の運転領域では上記第１排気弁および上記第１吸気弁を作動状態、上記第２排気弁および上記第２吸気弁を停止状態とする弁停止機構制御手段とを備えたものである。
【００１９】
このようにすると、弁停止機構の制御により、低負荷低回転域と高負荷、高回転側の運転領域とに応じた流通経路の切換えを容易に行なうことができる。
【００２０】
請求項６に係る発明は、請求項１乃至５のいずれかに記載の装置において、三元触媒を備えた排気通路に理論空燃比検出用の排気ガス濃度検出手段を設けるとともに、気筒間ガス通路にリーン空燃比検出用の排気ガス濃度検出手段を設け、上記制御手段は、上記２気筒接続状態にあるときに上記各排気ガス濃度検出手段による検出値に基き、先行気筒を理論空燃比よりも所定量大きいリーン空燃比とするとともに後続気筒を理論空燃比とするように各気筒に対する燃料噴射量をフィードバック制御するようにしたものである。
【００２１】
このようにすると、先行気筒を所定のリーン空燃比とするとともに後続気筒を理論空燃比とする制御か精度良く行われる。
【００２２】
請求項７に係る発明は、請求項１乃至６のいずれかに記載の装置において、上記先行気筒に対して筒内に直接燃料を噴射する燃料噴射弁を設け、上記制御手段は、上記２気筒接続状態にあるときに、先行気筒においてはリーン空燃比としつつ上記燃料噴射弁から圧縮行程で燃料を噴射することにより成層燃焼を行わせるようにしたものである。
【００２３】
このようにすると、先行気筒では成層化によりリーン空燃比でも良好に燃焼が行なわれる。
【００２４】
請求項８に係る発明は、請求項７記載の装置において、後続気筒に対して筒内に直接燃料を噴射する燃料噴射弁を設け、上記制御手段は、上記２気筒接続状態にあるときに、後続気筒においては理論空燃比としつつ上記燃料噴射弁から少なくとも燃料の一部を圧縮行程で噴射することにより成層燃焼を行わせるようにしたものである。
【００２５】
このようにすると、後続気筒では、理論空燃比とされつつ成層燃焼もしくは弱成層燃焼が行われることにより、多量のＥＧＲが行われているのと同等の状態でも燃焼が良好に行われる。
【００２６】
請求項９に係る発明は、請求項７記載の装置において、上記制御手段は、上記２気筒接続状態にあるときに、後続気筒においては理論空燃比としつつ均一燃焼を行わせるようにしたものである。
【００２７】
このようにすると、先行気筒から後続気筒へ導入される既燃ガスの温度が充分に高い場合等において後続気筒で燃料を均一に分散させても着火性を確保し得る場合に有効となる。
【００２８】
請求項１０に係る発明は、請求項７記載の装置において、気筒間ガス通路を構成する後続気筒の吸気通路に、後続気筒に燃料を供給する燃料噴射弁を設け、上記制御手段は、上記２気筒接続手段にあるときに、後続気筒においては理論空燃比としつつ上記燃料噴射弁から吸気行程で燃料を噴射することにより均一燃焼を行わせるようにしたものである。
【００２９】
このようにすると、先行気筒から後続気筒に導入されるガスが適度に放熱されるとともに、過剰空気と既燃ガスがミキシングされた理想的な多量のＥＧＲガス中に、このガスが後続気筒へ導入される過程で燃料が供給され、燃料の気化、さらにはこのガスとのミキシングが向上し、後続気筒において多量のＥＧＲが行われつつ燃焼性がさらに向上する。
【００３０】
その結果、エミッション、燃費性能を向上させることができる。また、上記のように、既燃ガスと空気と燃料とのミキシング性の向上、燃料の気化性能の向上によって、多量のＥＧＲ状態でありながら、後続気筒の自己着火運転の可能性が拡大する。
【００３１】
【発明の実施の形態】
以下、図面に基づいて本発明の実施の形態を説明する。
【００３２】
図１は本発明の一実施形態によるエンジンの概略構成を示し、図２はエンジン本体の一つの気筒とそれに対して設けられた吸・排気弁等の構造を概略的に示している。これらの図において、エンジン本体１は複数の気筒を有し、図示の実施形態では４つの気筒２Ａ〜２Ｄを有している。各気筒２Ａ〜２Ｄにはピストン３が嵌挿され、ピストン３の上方に燃焼室４が形成されている。
【００３３】
各気筒２の燃焼室４の頂部には点火プラグ７が装備され、そのプラグ先端が燃焼室４内に臨んでいる。この点火プラグ７には、電子制御による点火時期のコントロールが可能な点火回路８が接続されている。
【００３４】
燃焼室４の側方部には、燃焼室４内に燃料を直接噴射する燃料噴射弁９が設けられている。この燃料噴射弁９は、図略のニードル弁及びソレノイドを内蔵し、後述のパルス信号が入力されることにより、そのパルス入力時期にパルス幅に対応する時間だけ駆動されて開弁し、その開弁時間に応じた量の燃料を噴射するように構成されている。なお、この燃料噴射弁９には、図外の燃料ポンプにより燃料供給通路等を介して燃料が供給され、かつ、圧縮行程での燃焼室内の圧力よりも高い燃料圧力を与え得るように燃料供給系統が構成されている。
【００３５】
また、各気筒２Ａ〜２Ｄの燃焼室４に対して吸気ポート１１、１１ａ，１１ｂ及び排気ポート１２、１２ａ，１２ｂが開口し、これらのポートに吸気通路１５、排気通路２０等が接続されるとともに、各ポートが吸気弁３１、３１ａ，３１ｂ及び排気弁３２、３２ａ，３２ｂにより開閉されるようになっている。
【００３６】
そして、各気筒２Ａ〜２Ｄが所定の位相差をもって吸気、圧縮、膨張、排気の各行程からなるサイクルを行うようになっており、４気筒エンジンの場合、気筒列方向一端側から１番気筒２Ａ、２番気筒２Ｂ、３番気筒２Ｃ、４番気筒２Ｄと呼ぶと、図５に示すように上記サイクルが１番気筒２Ａ、３番気筒２Ｃ、４番気筒２Ｄ、２番気筒２Ｂの順にクランク角で１８０°ずつの位相差をもって行われるようになっている。なお、図５において、ＥＸは排気行程、ＩＮは吸気行程、Ｆは燃料噴射、Ｓは点火を表している。
【００３７】
排気行程と吸気行程が重なる一対の気筒間には、排気行程と吸気行程が重なるときの排気行程側の気筒（当明細書ではこれを先行気筒と呼ぶ）から吸気行程側の気筒（当明細書ではこれを後続気筒と呼ぶ）へ既燃ガスをそのまま導くことができるように、気筒間ガス通路２２が設けられている。当実施形態の４気筒エンジンでは、図５に示すように１番気筒２Ａの排気行程（ＥＸ）と２番気筒２Ｂの吸気行程（ＩＮ）とが重なり、また４番気筒２Ｄの排気行程（ＥＸ）と３番気筒２Ｃの吸気行程（ＩＮ）が重なるので、１番気筒２Ａと２番気筒２Ｂ、及び、４番気筒２Ｄと３番気筒２Ｃがそれぞれ一対をなし、１番気筒２Ａ及び４番気筒２Ｄが先行気筒、２番気筒２Ｂ及び３番気筒２Ｃが後続気筒となる。
【００３８】
各気筒の吸・排気ポートとこれに接続される吸気通路、排気通路及び気筒間ガス通路は、具体的には次のように構成されている。
【００３９】
先行気筒である１番気筒２Ａ及び４番気筒２Ｄには、それぞれ、新気を導入するための吸気ポート１１と、既燃ガス（排気ガス）を排気通路に送り出すための第１排気ポート１２ａと、既燃ガスを後続気筒に導出するための第２排気ポート１２ｂとが配設されている。また、後続気筒である２番気筒２Ｂ及び３番気筒２Ｃには、それぞれ、新気を導入するための第１吸気ポート１１ａと、先行気筒からの既燃ガスを導入するための第２吸気ポート１１ｂと、既燃ガスを排気通路に送り出すための排気ポート３２とが配設されている。
【００４０】
図１に示す例では、１番，４番気筒２Ａ，２Ｄにおける吸気ポート１１および２番，３番気筒２Ｂ，２Ｃにおける第１吸気ポート１１ａが、１気筒当り２個ずつ、燃焼室の左半部側に並列的に設けられる一方、１番，４番気筒２Ａ，２Ｄにおける第１排気ポート１２ａ及び第２排気ポート１２ｂならびに２番，３番気筒２Ｂ，２Ｃにおける第２吸気ポート１１ｂ及び排気ポート１２が、燃焼室の右半部側に並列的に設けられている。
【００４１】
１番，４番気筒２Ａ，２Ｄにおける吸気ポート１１および２番，３番気筒２Ｂ，２Ｃにおける第１吸気ポート１１ａには、吸気通路１５における気筒別の分岐吸気通路１６の下流端が接続されている。各分岐吸気通路１６の下流端近傍には、共通の軸を介して互いに連動する多連スロットル弁１７が設けられており、この多連スロットル弁１７は制御信号に応じてアクチュエータ１８により駆動され、吸入空気量を調節するようになっている。なお、吸気通路１５における集合部より上流の共通吸気通路には吸気流量を検出するエアフローセンサ１９が設けられている。
【００４２】
１番，４番気筒２Ａ，２Ｄにおける第１排気ポート１２ａおよび２番，３番気筒２Ｂ，２Ｃにおける排気ポート１２には、排気通路２０における気筒別の分岐排気通路２１の上流端が接続されている。また、１番気筒２Ａと２番気筒２Ｂとの間及び３番気筒２Ｃと４番気筒２Ｄとの間にそれぞれ気筒間ガス通路２２が設けられ、先行気筒である１番，４番気筒２Ａ，２Ｄの第２排気ポート１２ｂに気筒間ガス通路２２の上流端が接続されるとともに、後続気筒である２番，３番気筒２Ｂ，２Ｃの第２吸気ポート１１ｂに気筒間ガス通路２２の下流端が接続されている。
【００４３】
排気通路２０における分岐排気通路２１の下流の集合部にはＯ2センサ２３（理論空燃比検出用の排気ガス濃度検出手段）が設けられ、さらにその下流の排気通路２０には、排気浄化用の三元触媒２４が設けられている。この三元触媒２４は、一般に知られているように、排気ガスの空燃比が理論空燃比（つまり空気過剰率λがλ＝１）付近にあるときにＨＣ，ＣＯ及びＮＯｘに対して高い浄化性能を示す触媒である。
【００４４】
上記Ｏ2センサ２３は、排気ガス中の酸素濃度を検出することにより空燃比を検出するもので、特に理論空燃比付近で出力が急変するλＯ2センサにより構成されている。
【００４５】
また、上記各ガス通路２２には、排気ガス中の酸素濃度の変化（空燃比の変化）に対して出力がリニアに変化するリニアＯ2センサ２５（リーン空燃比検出用の排気ガス濃度検出手段）が設けられている。
【００４６】
各気筒の吸・排気ポートを開閉する吸・排気弁とこれらに対する動弁機構は、次のようになっている。
【００４７】
１番，４番気筒２Ａ，２Ｄにおける吸気ポート１１、第１排気ポート１２ａ及び第２排気ポート１２ｂにはそれぞれ吸気弁３１、第１排気弁３２ａ及び第２排気弁３２ｂが設けられ、また、２番，３番気筒２Ｂ，２Ｃにおける第１吸気ポート１１ａ、第２吸気ポート１１ｂ及び排気ポート１２にはそれぞれ第１吸気弁３１ａ、第２吸気弁３１ｂ及び排気弁３２が設けられている。そして、各気筒の吸気行程や排気行程が上述のような所定の位相差をもって行われるように、これら吸・排気弁がそれぞれカムシャフト３３，３４等からなる動弁機構により所定のタイミングで開閉するように駆動される。
【００４８】
さらに、これらの吸・排気弁のうちで第１排気弁３２ａ、第２排気弁３２ｂ、第１吸気弁３１ａ及び第２吸気弁３１ｂに対しては、各弁を作動状態と停止状態とに切換える弁停止機構３５が設けられている。この弁停止機構３５は、従来から知られているため詳しい図示は省略するが、例えば、カムシャフト３３，３４のカムと弁軸との間に介装されたタペットに作動油の給排が可能な油圧室が設けられ、この油圧室に作動油が供給されている状態ではカムの作動が弁に伝えられて弁が開閉作動され、油圧室から作動油が排出されたときにはカムの作動が弁に伝えられなくなることで弁が停止されるようになっている。
【００４９】
上記第１排気弁３２ａの弁停止機構３５と第１吸気弁３１ａの弁停止機構３５とに対する作動油給排用の通路３６には第１コントロール弁３７が、また第２排気弁３２ｂの弁停止機構３５と第２吸気弁３１ｂの弁停止機構３５とに対する作動油給排用の通路３８には第２コントロール弁３９がそれぞれ設けられている（図３参照）。
【００５０】
図３は駆動、制御系統の構成を示している。この図において、マイクロコンピュータ等からなるエンジン制御用のＥＣＵ（コントロールユニット）４０には、エアフローセンサ１９、Ｏ2センサ２３及びリニアＯ2センサ２５からの信号が入力され、さらに運転状態を判別するためにエンジン回転数を検出する回転数センサ４５及びアクセル開度（アクセルペダル踏込み量）を検出するアクセル開度センサ４６等からの信号も入力されている。また、このＥＣＵ４０から、各燃料噴射弁９と、多連スロットル弁１７のアクチュエータ１８と、上記第１，第２のコントロール弁３７，３９とに対して制御信号が出力されている。
【００５１】
上記ＥＣＵ４０は、運転状態判別手段４１、弁停止機構制御手段４２、吸入空気量制御手段４３及び燃料噴射制御手段４４を備えている。
【００５２】
運転状態判別手段４１は、上記回転数センサ４５及びアクセル開度センサ４６等からの信号によりエンジンの運転状態（エンジン回転数及びエンジン負荷）を調べ、運転状態が図４に示すような低負荷低回転側の運転領域Ａと、高負荷側ないし高回転側の運転領域Ｂとのいずれの領域にあるかを判別する。
【００５３】
弁停止機構制御手段４２は、運転状態が低負荷低回転側の運転領域Ａにある場合と高負荷側ないし高回転側の運転領域Ｂにある場合とに応じ、上記各コントロール弁３７，３９を制御することにより、各弁停止機構３５を次のように制御する。
【００５４】

Figure 0003711939
この弁停止機構制御手段４２とこれにより制御される各弁停止機構３５とにより、ガスの流通経路を後に詳述するように切換える流通経路切換手段が構成されている。
【００５５】
上記吸入空気量制御手段４３は、アクチュエータ１８を制御することによりスロットル弁１７の開度（スロットル開度）を制御するものであり、運転状態に応じてマップ等から目標吸入空気量を求め、その目標吸入空気量に応じてスロットル開度を制御する。この場合、低負荷低回転側の運転領域Ａでは、後述のように後続気筒（２番、３番気筒２Ｂ，２Ｃ）に対しては分岐吸気通路１６からの吸気導入が遮断されて先行気筒から導入されるガス中の過剰空気が燃焼に供せられるので、先行、後続の２気筒分の燃料の燃焼に必要な空気が先行気筒（１番、４番気筒２Ａ，２Ｄ）に供給されるように、スロットル開度が調節される。
【００５６】
上記燃料噴射制御手段４４は、各気筒２Ａ〜２Ｄに設けられた燃料噴射弁９からの燃料噴射量及び噴射タイミングをエンジンの運転状態に応じて制御するもので、特に運転状態が図４中の運転領域Ａにある場合と運転領域Ｂにある場合とで燃料噴射の制御が変更される。
【００５７】
すなわち、運転状態が低負荷低回転側の運転領域Ａにある場合、先行気筒（１番、４番気筒２Ａ，２Ｄ）に対しては、空燃比を理論空燃比よりも大きいリーン空燃比、好ましくは理論空燃比の略２倍もしくはそれ以上とするように燃料噴射量を制御するとともに、圧縮行程で燃料を噴射して成層燃焼を行わせるように噴射タイミングを設定する。一方、後続気筒（２番、３番気筒２Ｂ，２Ｃ）に対しては、先行気筒から導入されたリーン空燃比の既燃ガスに燃料を供給して理論空燃比とするように燃料噴射量を制御するとともに、既燃ガスが多い状況下で着火、燃焼が可能なように噴射タイミングが設定され、例えば着火性確保のため圧縮行程で燃料が噴射される。
【００５８】
上記燃料噴射量の制御は、エアフローセンサ１９及びＯ2センサ２３等からの出力に基くフィードバック制御により行われる。具体的には、先行気筒で所定のリーン空燃比、後続気筒で理論空燃比となるように、エアフローセンサ１９により検出される吸入空気量に応じてそれぞれの気筒に対する基本噴射量が演算されるとともに、気筒間ガス通路２２に設けられたリニアＯ2センサ２５からの出力に基いて先行気筒に対する燃料噴射量がフィードバック補正され、さらに排気通路２０に設けられたＯ2センサ２３からの出力に基いて後続気筒に対する燃料噴射量がフィードバック補正されるようになっている。
【００５９】
また、運転状態が高負荷側ないし高回転側の運転領域Ｂにある場合には、各気筒２Ａ〜２Ｄの空燃比を理論空燃比もしくはそれ以下とするように燃料噴射量を制御し、例えばこの運転領域Ｂのうちの大部分の領域において理論空燃比とし、全開負荷及びその付近の運転領域で理論空燃比よりリッチとする。そして、この場合に、各気筒２Ａ〜２Ｄに対して吸気行程で燃料を噴射することにより均一燃焼を行わせるように噴射タイミングを設定する。
【００６０】
以上のような当実施形態の装置の作用を、図５〜図７を参照しつつ説明する。
【００６１】
低負荷低回転側の運転領域Ａでは前述のように第１排気弁３２ａ及び第１吸気弁３１ａが停止状態、第２排気弁３２ｂ及び第２吸気弁３１ｂが作動状態とされることにより、実質的な新気及びガスの流通経路は図６に示すようになり、先行気筒（１番，４番気筒）２Ａ，２Ｄから排出される既燃ガスがそのまま気筒間ガス通路２２を介して後続気筒（２番，３番気筒）２Ｂ，２Ｃに導入されるとともに、この後続気筒２Ｂ，２Ｃから排出される既燃ガスのみが三元触媒２４を備えた排気通路２０に導かれるような２気筒接続状態とされる。
【００６２】
この状態において、先行気筒２Ａ，２Ｄにそれぞれ吸気行程で吸気通路１５から新気が導入され（図６中の矢印ａ）、先行気筒２Ａ，２ＤではリニアＯ2センサ２５により検出される空燃比が所定リーン空燃比となるように燃料噴射量がフィードバック制御されつつ圧縮行程で燃料が噴射され、かつ、所定点火時期に点火が行われて、リーン空燃比での成層燃焼が行われる（図５参照）。
【００６３】
その後、先行気筒２Ａ，２Ｄの吸気行程と後続気筒２Ｂ，２Ｃの排気行程が重なる期間に、先行気筒２Ａ，２Ｄから排出された既燃ガスがガス通路２２を通って後続気筒２Ｂ，２Ｃに導入される（図５中の白抜き矢印及び図６中の矢印ｂ）。そして、後続気筒２Ｂ，２Ｃでは、先行気筒２Ａ，２Ｄから導入されたリーン空燃比の既燃ガスに燃料が供給されて理論空燃比となるように、Ｏ2センサ２３の出力に基いて燃料噴射量が制御されつつ、適当なタイミング（例えば圧縮行程）で燃料が噴射され、かつ、所定点火時期に点火が行われて燃焼が行われる（図５参照）。後続気筒２Ｂ，２Ｃでの燃焼後の既燃ガスは、三元触媒２４を備えた排気通路２０に排出される（図６中の矢印ｃ）。
【００６４】
このように、先行気筒２Ａ，２Ｄではリーン空燃比での成層燃焼が行われることにより、熱効率が高められるとともにポンピングロスが低減され、これらの相乗効果で大幅に燃費が改善される。また、後続気筒２Ｂ，２Ｃでは空気過剰状態の既燃ガスに対し燃料が供給されて理論空燃比に制御されつつ燃焼が行われることにより、先行気筒２Ａ，２Ｄのようにリーン空燃比で成層燃焼が行われるものと比べると熱効率では多少劣るものの、ポンピングロス低減による燃費改善効果は充分に得られる。
【００６５】
しかも、後続気筒２Ｂ，２Ｃから排気通路２０に排出されるガスは理論空燃比であるため、従来のリーンバーンエンジンのようにリーンＮＯｘ触媒を設ける必要がなく、三元触媒２４だけで充分に排気浄化性能が確保される。
【００６６】
そして、リーンＮＯｘ触媒を設ける必要がないことから、リーンＮＯｘ触媒のＮＯｘ吸蔵量増大時におけるＮＯｘの放出、還元のための一時的な空燃比のリッチ化を行う必要がなく、燃費改善の目減りが避けられる。さらに、リーンＮＯｘ触媒の硫黄被毒の問題が生じることもない。
【００６７】
また、先行気筒２Ａ，２Ｄでは理論空燃比の略２倍もしくはそれ以上のリーン空燃比とされることでＮＯｘ発生量が比較的少なく抑えられ、後続気筒２Ｂ，２Ｃでは、先行気筒２Ａ，２Ｄから既燃ガスが導入されることで多量のＥＧＲが行われているのと同等の状態となることからＮＯｘの発生が充分に抑制される。このような点からもエミッションの向上に有利となる。
【００６８】
また、後続気筒２Ｂ，２Ｃには先行気筒２Ａ，２Ｄからの既燃ガスが気筒間ガス通路２２を介して導入されるが、この気筒間ガス通路２２で通路長の調整等により放熱量を調整し、これによって後続気筒２Ｂ，２Ｃに導入される既燃ガスの温度を調整することができる。そして、このように既燃ガスの温度を調整するとともに、後続気筒２Ｂ，２Ｃに対する燃料噴射タイミングを適宜調整することにより、多量の既燃ガスが導入される後続気筒２Ｂ，２Ｃにおいても、着火、燃焼性を良好に保つことができる。
【００６９】
なお、先行気筒２Ａ，２Ｄから後続気筒２Ｂ，２Ｃに導入されるガス中の過剰酸素の割合が少なくなると後続気筒２Ｂ，２Ｃでの燃焼安定性が損なわれるが、先行気筒２Ａ，２Ｄにおいて理論空燃比の略２倍もしくはそれ以上のリーン空燃比とされれば、後続気筒２Ｂ，２Ｃでの燃焼安定性は確保される。
【００７０】
一方、高負荷側ないし高回転側の運転領域Ｂでは前述のように第１排気弁３２ａ及び第１吸気弁３１ａが作動状態、第２排気弁３２ｂ及び第２吸気弁３１ｂが停止状態とされることにより、実質的な新気及びガスの流通経路は図７に示すようになり、実質的に各気筒２Ａ〜２Ｄの吸気ポート３１，３１ａ及び排気ポート１２ａ，１２が独立し、吸気通路１５から各気筒２Ａ〜２Ｄの吸気ポート３１，３１ａに新気が導入されるとともに各気筒２Ａ〜２Ｄの排気ポート３１，３１ａから排気通路２０に既燃ガスが排出される。そしてこの場合は、理論空燃比もしくはそれよりリッチとなるように吸入空気量及び燃料噴射量が制御されることにより、出力性能が確保される。
【００７１】
なお、本発明の装置の具体的構成は上記実施形態に限定されず、種々変更可能である。他の実施形態を以下に説明する。
【００７２】
▲１▼上記の基本実施形態では、後続気筒に対する燃料噴射時期を圧縮行程とすることにより、後続気筒では理論空燃比での成層燃焼を行わせるようにしているが、図８に示すように、後続気筒に対しては吸気行程と圧縮行程の２回に分けて分割噴射（F１，F２）を行うようにしてもよい。このようにすれば、点火プラグ付近に燃料が集まりすぎることが避けられて、弱成層状態で燃焼が行われる。
【００７３】
また、先行気筒から後続気筒へ導入される既燃ガスの温度が充分に高いこと等により後続気筒で燃料を均一に分散させても着火性を確保し得る場合には、図９に示すように、後続気筒に対する燃料噴射を吸気行程一括噴射としてもよい。
【００７４】
▲２▼吸・排気ポート及び気筒間ガス通路は図１０に示すような配置構成としてもよい。すなわち、この図において、先行気筒である１番，４番気筒２Ａ，２Ｄには燃焼室の左半部側に吸気ポート１１が設けられるとともに右半部側に第１排気ポート１２ａ及び第２排気ポート１２ｂが設けられ、後続気筒である２番，３番気筒２Ｂ，２Ｃには燃焼室の左半部側に第１吸気ポート１１ａ及び第２吸気ポート１１ｂが設けられるとともに右半部側に排気ポート１２が設けられている。また、気筒間ガス通路２２は、エンジン本体を気筒列方向と直交する方向に横切った状態で、両端が先行気筒２Ａ，２Ｄの第２排気ポート１２ｂと後続気筒２Ｂ，２Ｃの第２吸気ポート１１ｂとに接続されている。その他の構成は図１、図２に示す実施形態と同様である。
【００７５】
▲３▼基本実施形態では弁停止機構を用いて流通経路切換手段を構成しているが、図１１のように通路中に設けた開閉弁を用いて流通経路切換手段を構成してもよい。
【００７６】
すなわち、この図において、後続気筒である２番気筒２Ｂ及び３番気筒２Ｃの各第１吸気ポート１１ａに通じる分岐吸気通路１６に吸気側開閉弁４８ａ，４９ａが設けられるとともに、先行気筒である１番気筒2Ａ及び４番気筒２Ｄの各第１排気ポート１２ａに通じる分岐排気通路２１に排気側開閉弁４８ｂ，４９ｂが設けられ、さらに、１番気筒２Ａと２番気筒２Ｂとの間及び４番気筒２Ｄと３番気筒２Ｃとの間の各気筒間ガス通路２２にガス通路開閉弁４８ｃ，４９ｃが設けられている。これらの開閉弁４８ａ，４９ａ，４８ｂ，４９ｂ，４８ｃ，４９ｃは、それぞれが設けられた通路を開通する状態と遮断する状態とに切換可能とされ、図外のアクチュエータにより作動されるようになっている。
【００７７】
そして、図外の制御手段により、運転状態が低負荷低回転側の運転領域Ａにある場合と高負荷側ないし高回転側の運転領域Ｂにある場合とに応じ、上記各開閉弁が次のように制御される。
【００７８】
Figure 0003711939
運転領域ＡとＢとの間での運転状態の移行時において各開閉弁の状態を切換える時の切換作動は、図１２中に示す切換可能期間内に行えばよい。つまり、一対の気筒の排気行程と吸気行程とが重なる期間中に各開閉弁の状態を切換えると、後続気筒に先行気筒からの既燃ガスと新気とが入り混じって導入される等の不具合が生じるので、１番気筒２Ａの排気行程と２番気筒２Ｂの吸気行程とが重なる期間を除いた期間内に開閉弁４８ａ，４８ｂ，４８ｃを切換作動させるとともに、４番気筒２Ｄの排気行程と３番気筒２Ｃの吸気行程とが重なる期間を除いた期間内に開閉弁４８ａ，４８ｂ，４８ｃを切換作動させるようにすればよい。
【００７９】
こうして、開閉弁４８ａ，４９ａ，４８ｂ，４９ｂ，４８ｃ，４９ｃとこれを制御する制御手段により流通経路切換手段が構成される。
【００８０】
また、各気筒のポートに設けられた吸気弁３１、第１，第２排気弁３２ａ，３２ｂ、第１，第２吸気弁３１ａ，３１ｂ及び排気弁３２は、いずれも、図外の動弁機構により常に開閉作動されるようになっている。各燃料噴射弁９からの燃料噴射の制御等は上記実施形態と同様である。
【００８１】
なお、５０は吸気通路１５に設けられたスロットル弁である。
【００８２】
この実施形態によっても、運転領域Ａでは２気筒接続状態とされて、先行気筒２Ａ，２Ｄで超リーン燃焼が行われ、この先行気筒から排出される既燃ガスが気筒間ガス通路２２を介して後続気筒２Ｂ，２Ｃに導入され、後続気筒２Ｂ，２Ｃでリーン空燃比の既燃ガスに燃料が供給されて理論空燃比とされた状態で燃焼が行われ、この後続気筒２Ｂ，２Ｃから排出されるガスのみが三元触媒２４を備えた排気通路２０に導かれる。一方、運転領域Ｂでは、各気筒２Ａ〜２Ｄの吸気ポートと排気ポートとが独立して、吸気通路から各気筒の吸気ポートに新気が導入されるとともに各気筒の排気ポートから排出される排気ガスが上記排気通路２０に導かれる。こうして、基本実施形態と同様の作用、効果が得られる。
【００８３】
また、当実施形態のような流通経路切換手段によれば、その構造が比較的簡単になるとともに、運転状態移行時における開閉弁の切換動作は図１２中に示すような切換可能期間内に行えばよく、切換タイミングに著しく高い精度が要求されることはないので、制御も容易である。
【００８４】
▲４▼各気筒に対する通路及び流通経路切換手段は、図１３のように構成してもよい。
【００８５】
すなわち、この図において、エンジン本体の各気筒２Ａ〜２Ｄにはそれぞれ吸気ポート５１及び排気ポート５２が開口し、これらのポートに設けられた吸気弁５３及び排気弁５４は図外の動弁機構により常に開閉作動されるようになっている。上記各気筒２Ａ〜２Ｄの吸気ポート５１に分岐吸気通路１６Ａ〜１６Ｄが接続され、各気筒２Ａ〜２Ｄの排気ポート５２に分岐排気通路２１Ａ〜２１Ｄが接続されるとともに、先行気筒（１番，４番気筒）２Ａ，２Ｄに対する分岐排気通路２１Ａ，２１Ｄの集合部と後続気筒（２番，３番気筒）２Ｂ，２Ｃに対する分岐排気通路２１Ｂ，２１Ｃの集合部との間に気筒間ガス通路５５が接続され、この気筒間ガス通路５５に第１開閉弁５７が設けられている。
【００８６】
また、先行気筒２Ａ，２Ｄに対する分岐吸気通路１６Ａ，１６Ｄの集合部が吸気通路上流部に常に連通するとともに、後続気筒２Ｂ，２Ｃに対する分岐吸気通路１６Ｂ，１６Ｃの集合部と吸気通路上流部との間の連通部にはこの連通部を開閉する第２開閉弁５７が設けられている。一方、後続気筒２Ｂ，２Ｃに対する分岐排気通路２１Ｂ，２１Ｃの集合部が排気通路下流部に常に連通するとともに、先行気筒２Ａ，２Ｄに対する分岐排気通路２１Ａ，２１Ｄの集合部と排気通路下流部との間の連通部にはこの連通部を開閉する第３開閉弁５８が設けられている。
【００８７】
そして、図外の制御手段により、運転状態が低負荷低回転側の運転領域Ａにある場合と高負荷側ないし高回転側の運転領域Ｂにある場合とに応じ、上記各開閉弁５６，５７，５８が次のように制御される。
【００８８】
Figure 0003711939
こうして開閉弁５６，５７，５８とこれを制御する制御手段により流通経路切換手段が構成される。各燃料噴射弁９からの燃料噴射の制御等は上記実施形態と同様である。
【００８９】
この実施形態によっても、運転領域Ａでは、排気行程と吸気行程が重なる一対の気筒間において先行気筒２Ａ，２Ｄから排出される既燃ガスがそのまま後続気筒２Ｂ，２Ｃに気筒間ガス通路５５を介して導入されるとともに、この後続気筒２Ｂ，２Ｃから排出される既燃ガスのみが三元触媒２４を備えた排気通路２０に導かれるような２気筒接続状態とされ、一方、運転領域Ｂでは、各気筒２Ａ〜２Ｄの吸気ポート５１と排気ポート５２とが独立して、吸気通路から各気筒の吸気ポート５１に新気が導入されるとともに各気筒の排気ポート５２から排出される排気ガスが上記排気通路２０に導かれることとなる。
【００９０】
▲５▼前述のように後続気筒2Ｂ，2Ｃで燃料を均一に分散させても着火性を確保し得る場合には、後続気筒2Ｂ，2Ｃに設ける燃料噴射弁は必ずしも燃焼室に直接燃料を噴射する直噴タイプに限定されず、例えば図１４に示すように、気筒間ガス通路を構成する後続気筒2Ｂ，2Ｃの吸気通路に、後続気筒2Ｂ，2Ｃに燃料を供給する燃料噴射弁９´を設けてもよい。この場合、後続気筒2Ｂ，2Ｃにおいては理論空燃比としつつ上記燃料噴射弁９´から吸気行程で燃料を噴射することにより均一燃焼を行わせるようにする。
【００９１】
このようにすると、先行気筒2Ａ，2Ｄから後続気筒2Ｂ，2Ｃに導入されるガスが適度に放熱されるとともに過剰空気と既燃ガスがミキシングされた理想的な多量のＥＧＲガス中に、このガスが後続気筒2Ｂ，2Ｃへ導入される過程で燃料が供給され、燃料の気化、さらにはこのガスとのミキシングが向上し、後続気筒2Ｂ，2Ｃにおいて多量のＥＧＲが行われつつ燃焼性がさらに向上する。
【００９２】
▲６▼上記各実施形態に示すような構造に加えて過給機を設け、例えば図１５に示すようなターボ過給機６０を設けてもよい。同図において、ターボ過給機は６０は、排気通路２０に設けられたタービン６１と、吸気通路１５に設けられたコンプレッサ６２とを有し、排気通路２０を流れる排気ガスのエネルギーでタービン６１が回転し、それに連動したコンプレッサ６２の回転により、吸気を過給するようになっている。６３はコンプレッサ６２の下流の吸気通路１５に設けられたインタークーラである。
【００９３】
このようにすれば、比較的高負荷側まで、上記２気筒接続状態として燃費改善を図るようにすることができる。
【００９４】
▲７▼上記各実施形態では、流通経路切換手段により運転状態が低負荷低回転側の運転領域Ａにある場合と高負荷側ないし高回転側の運転領域Ｂにある場合とに応じて新気及びガスの流通経路を切換えるようにしているが、全運転領域にわたって新気及びガスの流通経路を上記２気筒接続状態としてもよい。
【００９５】
▲８▼本発明の装置は４気筒以外の多気筒エンジンにも適用可能である。そして、例えば６気筒等では１つの気筒の排気行程と別の気筒の吸気行程が完全に重なり合うことはないが、このような場合は、一方の気筒の排気行程が他方の気筒の吸気行程より先行するとともに、両行程が部分的に重なり合う２つの気筒を先行、後続の一対の気筒とすればよい。
【００９６】
▲９▼上記各実施形態に示すような構造に加え、先行気筒に対してのみＥＧＲを行なうようにしてもよい。このようすれば、先行気筒でのＮＯｘの発生が抑えられ、後続気筒では先行気筒から導入される既燃ガスがＥＧＲと同様にＮＯｘの発生を押えるので、有効にＮＯｘを減少させることができる。
【００９７】
【発明の効果】
以上のように本発明の制御装置は、排気行程と吸気行程が重なる一対の気筒間において排気行程の先行気筒から排出される既燃ガスがそのまま気筒間ガス通路を介して吸気行程の後続気筒に導入され、この後続気筒から排出される既燃ガスのみが三元触媒を備えた排気通路に導かれるようにするとともに、先行気筒ではリーン空燃比とした状態で燃焼を行わせ、上記後続気筒では先行気筒から導入されたリーン空燃比の既燃ガスに燃料を供給して理論空燃比とした状態で燃焼を行わせるようにしているため、先行気筒でのリーン燃焼による熱効率向上およびポンピングロス低減ならびに後続気筒でのポンピングロス低減等により、燃費が大幅に改善され、しかも、三元触媒だけで充分な排気浄化作用を持たせることができる。従って、リーンＮＯｘ触媒が不要となり、コストが低減されるとともに、リーン運転中に一時的な空燃比のリッチ化を行う必要がなくて、このリッチ化による燃費改善の目減りが避けられ、さらに、ＮＯｘ触媒の硫黄被毒の問題も解消することができる。
【００９８】
また、先行気筒から排出される高温の既燃ガスが気筒間ガス通路を通って後続気筒に導入されようになっているため、気筒間ガス通路で、放熱によりガス温度を調整し得るとともに、空気過剰の既燃ガスの充分にミキシングすることができ、これによって後続気筒での燃焼性を向上することができる。
【図面の簡単な説明】
【図１】本発明の一実施形態による装置を備えたエンジン全体の概略平面図である。
【図２】エンジン本体等の概略断面図である。
【図３】制御系統のブロック図である。
【図４】運転領域を示す説明図である。
【図５】各気筒の排気行程、吸気行程、燃料噴射時期および点火時期等を示す図である。
【図６】低負荷低回転時の実質的な新気およびガスの流通経路を示す説明図である。
【図７】高負荷、高低回転側の運転領域にある時の実質的な新気およびガスの流通経路を示す説明図である。
【図８】後続気筒の燃料噴射時期の別の例を示す図である。
【図９】後続気筒の燃料噴射時期のさらに別の例を示す図である。
【図１０】吸・排気ポート及び気筒間ガス通路等の構成の別の実施形態を示す概略平面図である。
【図１１】流通経路切換手段等の別の実施形態を示す概略平面図である。
【図１２】図１１の実施形態による場合の運転状態移行時の開閉弁の切換可能期間を示す説明図である。
【図１３】流通経路切換手段等のさらに別の実施形態を示す概略平面図である。
【図１４】後続気筒の吸気通路に燃料噴射弁を設けた実施形態を示す概略平面図である。
【図１５】ターボ過給機を設けた実施形態を示す概略平面図である。
【符号の説明】
１ エンジン本体
２Ａ〜２Ｄ 気筒
９ 燃料噴射弁
１１ 吸気ポート
１１ａ 第１吸気ポート
１１ｂ 第２吸気ポート
１２ 排気ポート
１２ａ 第１排気ポート
１２ｂ 第２排気ポート
１５ 吸気通路
２０ 排気通路
２２ 気筒間ガス通路
２４ 三元触媒
３１ 吸気弁
３１ａ 第１吸気弁
３１ｂ 第２吸気弁
３２ 排気弁
３２ａ 第１排気弁
３２ｂ 第２排気弁
３５ 弁停止機構
４０ ＥＣＵ
４１ 運転状態判別手段
４２ 弁停止機構制御手段
４３ 吸入空気量制御手段
４４ 燃料噴射制御手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spark ignition engine control device, and more particularly to a device for controlling the combustion state of each cylinder in a multi-cylinder engine to improve fuel consumption and emissions.
[0002]
[Prior art]
Conventionally, in a spark ignition engine, a technique for improving fuel efficiency by performing combustion in a state where the air-fuel ratio of the air-fuel mixture in each cylinder is set to a lean air-fuel ratio larger than the stoichiometric air-fuel ratio is known. As disclosed in Japanese Patent Application Laid-Open No. 10-274085, a stratified combustion is provided by injecting fuel directly into a combustion chamber and injecting fuel from the fuel injection valve in a compression stroke in a low rotation and low load region. It is known that the super lean combustion is realized by this.
[0003]
In such an engine, an ordinary three-way catalyst (a catalyst having a high purification performance in the vicinity of the theoretical air-fuel ratio with respect to HC, CO, and NOx) alone as an exhaust gas purification catalyst is sufficient for NOx during lean operation. Since purification performance cannot be obtained, a lean NOx catalyst is provided that adsorbs NOx in an oxygen-excessive atmosphere and removes and reduces NOx in an oxygen-concentrated atmosphere as shown in the above publication. When such a lean NOx catalyst is used, if the NOx adsorption amount of the lean NOx catalyst increases during the lean operation, for example, as shown in the above publication, additional fuel is injected during the expansion stroke in addition to the main combustion. As a result, the air-fuel ratio of the exhaust gas is enriched and CO is generated, thereby promoting NOx separation and reduction.
[0004]
[Problems to be solved by the invention]
The engine that performs the conventional lean operation as described above requires the lean NOx catalyst in order to ensure the NOx purification performance during the lean operation. Further, a three-way catalyst is also required for exhaust purification in a region operated at a stoichiometric air-fuel ratio such as a high load region, the lean NOx catalyst is provided in addition to the three-way catalyst, and the lean A NOx catalyst requires a relatively large capacity in order to secure a certain amount of NOx adsorption, and is expensive compared to a three-way catalyst, which is disadvantageous in terms of cost.
[0005]
Moreover, in order to maintain the purification performance of the lean NOx catalyst, the NOx is temporarily removed by the removal of NOx, the supply of additional fuel for reduction, etc. at predetermined intervals such that the NOx adsorption amount increases as described above. It is necessary to enrich the air-fuel ratio, which reduces the fuel efficiency improvement effect due to lean combustion.
[0006]
Furthermore, when the fuel used contains a large amount of sulfur, the lean NOx catalyst is susceptible to sulfur poisoning, and in order to eliminate this sulfur poisoning, regeneration processing such as heating the catalyst and supplying a reducing material is required. This may cause a reduction in fuel consumption improvement effect and a decrease in durability.
[0007]
The present invention has been made in consideration of the conventional problems as described above, and improves exhaust gas purification performance by using a three-way catalyst without the need for a lean NOx catalyst while providing an improvement in fuel efficiency due to lean combustion. A control device for a spark ignition engine that can be provided is provided.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 is a multi-cylinder spark ignition engine in which each cylinder performs a cycle including intake, compression, expansion, and exhaust strokes with a predetermined phase difference. In the region, the burned gas discharged from the preceding cylinder which is the cylinder on the exhaust stroke side between the pair of cylinders where the exhaust stroke and the intake stroke overlap is directly passed to the subsequent cylinder which is the cylinder on the intake stroke side via the inter-cylinder gas passage The gas flow path is configured in a two-cylinder connection state in which only the gas introduced and exhausted from the subsequent cylinder is guided to the exhaust passage provided with the three-way catalyst, and when the two-cylinder connection state is established, In the preceding cylinder, combustion is performed with a lean air-fuel ratio that is a predetermined amount larger than the stoichiometric air-fuel ratio, and in the above-mentioned subsequent cylinder, fuel is supplied to the burned gas of the lean air-fuel ratio introduced from the preceding cylinder. So as to perform combustion while the stoichiometric air-fuel ratio Te, those having a control unit for controlling the fuel supply to each cylinder.
[0009]
According to this configuration, at least in the low-load low-rotation region, the preceding cylinder performs combustion at a lean air-fuel ratio, so that the thermal efficiency is increased and the pumping loss is reduced, thereby obtaining a significant fuel efficiency improvement effect. Further, in the succeeding cylinder, fuel is supplied to the burned gas having a lean air-fuel ratio introduced from the preceding cylinder and the stoichiometric air-fuel ratio is set, and at least the fuel efficiency effect by reducing the pumping loss is obtained. In addition, only the stoichiometric burned gas discharged from the subsequent cylinder is guided to the exhaust passage provided with the three-way catalyst, so that the exhaust gas purification performance can be sufficiently ensured with only the three-way catalyst, and the lean NOx catalyst is unnecessary. Become.
[0010]
In addition, the NOx generation amount is suppressed to be relatively small by performing combustion at a lean air-fuel ratio in the preceding cylinder, and a large amount of EGR is performed in the succeeding cylinder by introducing burned gas from the preceding cylinder. Therefore, the generation of NOx is sufficiently suppressed, which is advantageous for improving the emission.
[0011]
The high-temperature gas discharged from the preceding cylinder is appropriately radiated while passing through the inter-cylinder gas passage to adjust the temperature, and is mixed so that excess air and burned gas in this gas are evenly dispersed. By being introduced to the succeeding cylinder in a state where it is in a state, it becomes an ideal state for a large amount of EGR. Further, since the fuel is injected into a relatively high temperature gas, the vaporization of the fuel may be promoted, and the combustion is favorably performed in the subsequent cylinder.
[0012]
According to a second aspect of the present invention, in the apparatus of the first aspect, the two cylinders in which the exhaust stroke and the intake stroke completely overlap, or the exhaust stroke of one of the cylinders precedes the intake stroke of the other cylinder and both strokes. The two cylinders that partially overlap each other are a pair of preceding and succeeding cylinders.
[0013]
In this way, the burned gas discharged from the preceding cylinder in the exhaust stroke is smoothly introduced into the subsequent cylinder in the intake stroke through the inter-cylinder gas passage, and the pumping loss is effectively reduced.
[0014]
According to a third aspect of the present invention, in the apparatus according to the first or second aspect, the air-fuel ratio of the preceding cylinder when the two cylinders are connected is approximately twice or more than the theoretical air-fuel ratio.
[0015]
In this way, the fuel efficiency improvement effect due to lean combustion in the preceding cylinder is sufficiently enhanced, and excessive air in the burned gas introduced into the succeeding cylinder is prevented from becoming too small, and combustion in the succeeding cylinder is avoided. Sex is secured.
[0016]
According to a fourth aspect of the present invention, in the device according to any one of the first to third aspects, the intake port and the exhaust port of each cylinder are made independent from each other in the operating region on the high load, high rotation side, and The control means comprises a flow path switching means for introducing fresh air into the intake port of the cylinder and switching the flow path of fresh air and gas so as to guide the exhaust gas discharged from the exhaust port of each cylinder to the exhaust passage. The air-fuel ratio of each cylinder is set to the stoichiometric air-fuel ratio or lower in the operating region on the high load and high rotation side.
[0017]
In this way, while improving fuel efficiency and emission in the low load and low rotation range, output performance is ensured in the high load and high rotation side operation region.
[0018]
According to a fifth aspect of the present invention, in the apparatus according to the fourth aspect, the leading cylinder communicates with the intake port leading to the intake passage, the first exhaust port leading to the exhaust passage, and the second cylinder communicating with the inter-cylinder gas passage. While providing an exhaust port, the subsequent cylinder is provided with a first intake port that communicates with the intake passage, a second intake port that communicates with the inter-cylinder gas passage, and an exhaust port that communicates with the exhaust passage. As switching means, the first and second exhaust valves for opening and closing the first and second exhaust ports of the preceding cylinder and the first and second intake valves for opening and closing the first and second intake ports of the succeeding cylinder are operated. And a valve stop mechanism for switching between the first exhaust valve and the stop state, and in the low load and low rotation range, the first exhaust valve and the first intake valve are stopped, the second exhaust valve and the second intake valve are operated, and a high load On the high rotation side In the rolling region is obtained and a said first exhaust valve and the operating state of the first intake valve, the valve stop mechanism controller that the second exhaust valve and the second intake valve is stopped.
[0019]
If it does in this way, switching of a distribution route according to the low load low rotation region and the high load, high rotation side operation region can be easily performed by control of the valve stop mechanism.
[0020]
According to a sixth aspect of the present invention, in the apparatus according to any one of the first to fifth aspects, the exhaust gas concentration detecting means for detecting the theoretical air-fuel ratio is provided in the exhaust passage provided with the three-way catalyst, and the inter-cylinder gas passage is provided. Is provided with an exhaust gas concentration detection means for detecting a lean air-fuel ratio, and the control means determines that the preceding cylinder is less than the stoichiometric air-fuel ratio based on the detection value by each exhaust gas concentration detection means when the two cylinders are connected. The fuel injection amount for each cylinder is feedback controlled so that the lean air-fuel ratio is larger by a predetermined amount and the subsequent cylinder is the stoichiometric air-fuel ratio.
[0021]
In this way, the control is performed with high precision so that the preceding cylinder has a predetermined lean air-fuel ratio and the succeeding cylinder has a stoichiometric air-fuel ratio.
[0022]
According to a seventh aspect of the present invention, in the apparatus according to any one of the first to sixth aspects, a fuel injection valve that directly injects fuel into the cylinder is provided for the preceding cylinder, and the control means includes the two cylinders In the connected state, stratified combustion is performed by injecting fuel in the compression stroke from the fuel injection valve in the preceding cylinder while maintaining a lean air-fuel ratio.
[0023]
In this way, the preceding cylinder performs combustion well even at a lean air-fuel ratio due to stratification.
[0024]
According to an eighth aspect of the present invention, in the apparatus of the seventh aspect, a fuel injection valve that directly injects fuel into the cylinder for the subsequent cylinder is provided, and the control means is in the two-cylinder connected state. In the succeeding cylinder, stratified combustion is performed by injecting at least a part of the fuel in the compression stroke from the fuel injection valve while maintaining the stoichiometric air-fuel ratio.
[0025]
In this way, in the succeeding cylinder, stratified combustion or weak stratified combustion is performed while maintaining the stoichiometric air-fuel ratio, so that combustion is performed well even in a state equivalent to a large amount of EGR being performed.
[0026]
According to a ninth aspect of the present invention, in the apparatus according to the seventh aspect, when the control means is in the two-cylinder connected state, the subsequent cylinder performs uniform combustion while maintaining the stoichiometric air-fuel ratio. is there.
[0027]
This is effective when the ignitability can be ensured even if the fuel is uniformly dispersed in the succeeding cylinder when the temperature of the burned gas introduced from the preceding cylinder to the succeeding cylinder is sufficiently high.
[0028]
According to a tenth aspect of the present invention, in the apparatus according to the seventh aspect, a fuel injection valve for supplying fuel to the succeeding cylinder is provided in the intake passage of the succeeding cylinder constituting the inter-cylinder gas passage. When in the cylinder connecting means, the subsequent cylinder is made to perform uniform combustion by injecting fuel from the fuel injection valve in the intake stroke while maintaining the stoichiometric air-fuel ratio.
[0029]
In this way, the gas introduced from the preceding cylinder to the succeeding cylinder is appropriately dissipated, and this gas is introduced into the succeeding cylinder in an ideal amount of EGR gas in which excess air and burned gas are mixed. In the process, fuel is supplied, fuel vaporization and further mixing with the gas are improved, and the combustibility is further improved while a large amount of EGR is performed in the subsequent cylinder.
[0030]
As a result, emission and fuel efficiency can be improved. Further, as described above, the possibility of the self-ignition operation of the succeeding cylinders is expanded in a large amount of EGR state by improving the mixing property of burned gas, air and fuel and improving the fuel vaporization performance.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0032]
FIG. 1 shows a schematic configuration of an engine according to an embodiment of the present invention, and FIG. 2 schematically shows a structure of one cylinder of an engine main body and intake / exhaust valves provided for the cylinder. In these drawings, the engine body 1 has a plurality of cylinders, and in the illustrated embodiment, has four cylinders 2A to 2D. A piston 3 is fitted into each of the cylinders 2 </ b> A to 2 </ b> D, and a combustion chamber 4 is formed above the piston 3.
[0033]
A spark plug 7 is provided at the top of the combustion chamber 4 of each cylinder 2, and the tip of the plug faces the combustion chamber 4. An ignition circuit 8 capable of controlling the ignition timing by electronic control is connected to the spark plug 7.
[0034]
A fuel injection valve 9 that directly injects fuel into the combustion chamber 4 is provided at a side portion of the combustion chamber 4. This fuel injection valve 9 incorporates a needle valve and a solenoid (not shown). When a pulse signal described later is input, the fuel injection valve 9 is driven for a time corresponding to the pulse width at the pulse input timing to open the valve. An amount of fuel corresponding to the valve time is injected. The fuel injection valve 9 is supplied with fuel by a fuel pump (not shown) through a fuel supply passage and the like, and is supplied with fuel higher than the pressure in the combustion chamber during the compression stroke. A system is configured.
[0035]
Further, intake ports 11, 11a, 11b and exhaust ports 12, 12a, 12b are opened to the combustion chambers 4 of the respective cylinders 2A to 2D, and an intake passage 15 and an exhaust passage 20 are connected to these ports. Each port is opened and closed by intake valves 31, 31a, 31b and exhaust valves 32, 32a, 32b.
[0036]
Each of the cylinders 2A to 2D performs a cycle including intake, compression, expansion, and exhaust strokes with a predetermined phase difference. In the case of a four-cylinder engine, the first cylinder 2A from one end in the cylinder row direction. As shown in FIG. 5, the above-mentioned cycle is performed in the order of the first cylinder 2A, the third cylinder 2C, the fourth cylinder 2D, and the second cylinder 2B. This is performed with a phase difference of 180 ° in angle. In FIG. 5, EX represents an exhaust stroke, IN represents an intake stroke, F represents fuel injection, and S represents ignition.
[0037]
Between a pair of cylinders in which the exhaust stroke and the intake stroke overlap, a cylinder on the intake stroke side (this specification is referred to as a preceding cylinder) from the cylinder on the exhaust stroke side when the exhaust stroke and the intake stroke overlap (this specification is referred to as a preceding cylinder) The inter-cylinder gas passage 22 is provided so that the burned gas can be directly introduced to the subsequent cylinder). In the four-cylinder engine of this embodiment, as shown in FIG. 5, the exhaust stroke (EX) of the first cylinder 2A and the intake stroke (IN) of the second cylinder 2B overlap, and the exhaust stroke (EX) of the fourth cylinder 2D. ) And the intake stroke (IN) of the third cylinder 2C overlap, so that the first cylinder 2A and the second cylinder 2B, and the fourth cylinder 2D and the third cylinder 2C form a pair, respectively, and the first cylinder 2A and the fourth cylinder The cylinder 2D is the preceding cylinder, the second cylinder 2B, and the third cylinder 2C are the subsequent cylinders.
[0038]
The intake / exhaust port of each cylinder and the intake passage, exhaust passage, and inter-cylinder gas passage connected to the cylinder are specifically configured as follows.
[0039]
The first cylinder 2A and the fourth cylinder 2D, which are the preceding cylinders, respectively include an intake port 11 for introducing fresh air, and a first exhaust port 12a for sending burned gas (exhaust gas) to the exhaust passage. A second exhaust port 12b for leading the burned gas to the subsequent cylinder is provided. The second cylinder 2B and the third cylinder 2C, which are the subsequent cylinders, respectively, have a first intake port 11a for introducing fresh air and a second intake port for introducing burned gas from the preceding cylinder. 11b and an exhaust port 32 for sending the burned gas to the exhaust passage.
[0040]
In the example shown in FIG. 1, the intake ports 11 in the first and fourth cylinders 2A and 2D and the first intake ports 11a in the second and third cylinders 2B and 2C are two per cylinder, the left half of the combustion chamber. The first exhaust port 12a and the second exhaust port 12b in the first and fourth cylinders 2A and 2D and the second intake port 11b and the exhaust port in the second and third cylinders 2B and 2C are provided in parallel on the part side. 12 are provided in parallel on the right half side of the combustion chamber.
[0041]
The intake port 11 in the first and fourth cylinders 2A and 2D and the first intake port 11a in the second and third cylinders 2B and 2C are connected to the downstream ends of the branch intake passages 16 for each cylinder in the intake passage 15. Yes. In the vicinity of the downstream end of each branch intake passage 16, a multiple throttle valve 17 that is linked to each other via a common shaft is provided. This multiple throttle valve 17 is driven by an actuator 18 in accordance with a control signal, The intake air amount is adjusted. Note that an air flow sensor 19 that detects an intake air flow rate is provided in a common intake passage upstream of the collecting portion in the intake passage 15.
[0042]
An upstream end of a branch exhaust passage 21 for each cylinder in the exhaust passage 20 is connected to the first exhaust port 12a in the first and fourth cylinders 2A and 2D and the exhaust port 12 in the second and third cylinders 2B and 2C. Yes. Further, an inter-cylinder gas passage 22 is provided between the first cylinder 2A and the second cylinder 2B and between the third cylinder 2C and the fourth cylinder 2D, and the first, fourth cylinder 2A, The upstream end of the inter-cylinder gas passage 22 is connected to the 2D second exhaust port 12b, and the downstream end of the inter-cylinder gas passage 22 is connected to the second intake port 11b of the second and third cylinders 2B and 2C as the subsequent cylinders. Is connected.
[0043]
A collecting portion downstream of the branch exhaust passage 21 in the exhaust passage 20 has O 2 A sensor 23 (exhaust gas concentration detection means for detecting the theoretical air-fuel ratio) is provided, and an exhaust gas purification three-way catalyst 24 is provided in the exhaust passage 20 downstream thereof. As is generally known, the three-way catalyst 24 is highly purified against HC, CO, and NOx when the air-fuel ratio of the exhaust gas is close to the stoichiometric air-fuel ratio (that is, the excess air ratio λ is λ = 1). It is a catalyst showing performance.
[0044]
O above 2 The sensor 23 detects the air-fuel ratio by detecting the oxygen concentration in the exhaust gas, and particularly the λO whose output changes suddenly near the stoichiometric air-fuel ratio. 2 It is composed of sensors.
[0045]
Each gas passage 22 has a linear O output whose output changes linearly with respect to a change in oxygen concentration in the exhaust gas (change in air-fuel ratio). 2 A sensor 25 (exhaust gas concentration detection means for detecting a lean air-fuel ratio) is provided.
[0046]
The intake / exhaust valves for opening and closing the intake / exhaust ports of each cylinder and the valve operating mechanism for these valves are as follows.
[0047]
The intake port 11, the first exhaust port 12a and the second exhaust port 12b in the first and fourth cylinders 2A and 2D are respectively provided with an intake valve 31, a first exhaust valve 32a and a second exhaust valve 32b. A first intake valve 31a, a second intake valve 31b, and an exhaust valve 32 are provided in the first intake port 11a, the second intake port 11b, and the exhaust port 12 in the No. 3 cylinders 2B and 2C, respectively. These intake / exhaust valves are opened and closed at predetermined timings by the valve mechanisms comprising the camshafts 33, 34, etc. so that the intake stroke and exhaust stroke of each cylinder are performed with the predetermined phase difference as described above. To be driven.
[0048]
Further, among these intake / exhaust valves, the first exhaust valve 32a, the second exhaust valve 32b, the first intake valve 31a, and the second intake valve 31b are switched between an operating state and a stopped state. A valve stop mechanism 35 is provided. The valve stop mechanism 35 has been known in the art and will not be shown in detail. For example, hydraulic oil can be supplied to and discharged from a tappet interposed between the cams of the camshafts 33 and 34 and the valve shaft. When a hydraulic oil is supplied to the hydraulic chamber, the operation of the cam is transmitted to the valve and the valve is opened and closed. When the hydraulic oil is discharged from the hydraulic chamber, the cam operation is not performed. The valve is stopped by not being able to be transmitted to.
[0049]
The first control valve 37 and the second exhaust valve 32b are stopped in the hydraulic oil supply / discharge passage 36 to the valve stop mechanism 35 of the first exhaust valve 32a and the valve stop mechanism 35 of the first intake valve 31a. A second control valve 39 is provided in each of the hydraulic oil supply / discharge passages 38 to the mechanism 35 and the valve stop mechanism 35 of the second intake valve 31b (see FIG. 3).
[0050]
FIG. 3 shows the configuration of the drive and control system. In this figure, an ECU (control unit) 40 for engine control composed of a microcomputer or the like is provided with an air flow sensor 19, O 2 Sensor 23 and linear O 2 A signal from the sensor 25 is input, and further, a signal from an engine speed sensor 45 for detecting the engine speed in order to determine an operating state, an accelerator position sensor 46 for detecting an accelerator position (depressing amount of an accelerator pedal), and the like are also included. Have been entered. The ECU 40 outputs control signals to the fuel injection valves 9, the actuator 18 of the multiple throttle valve 17, and the first and second control valves 37 and 39.
[0051]
The ECU 40 includes an operating state determination unit 41, a valve stop mechanism control unit 42, an intake air amount control unit 43, and a fuel injection control unit 44.
[0052]
The operating state discriminating means 41 checks the operating state of the engine (engine speed and engine load) based on the signals from the rotational speed sensor 45 and the accelerator opening sensor 46, and the operating state is low and low as shown in FIG. It is discriminated whether the operation area A is on the rotation side or the operation area B on the high load side or high rotation side.
[0053]
The valve stop mechanism control means 42 controls the control valves 37 and 39 according to whether the operation state is in the operation region A on the low load / low rotation side or in the operation region B on the high load side or the high rotation side. By controlling, each valve stop mechanism 35 is controlled as follows.
[0054]
Figure 0003711939
The valve stop mechanism control means 42 and each valve stop mechanism 35 controlled thereby constitute a flow path switching means for switching the gas flow path as will be described in detail later.
[0055]
The intake air amount control means 43 controls the opening degree of the throttle valve 17 (throttle opening degree) by controlling the actuator 18, and obtains a target intake air amount from a map or the like according to the operating state. The throttle opening is controlled according to the target intake air amount. In this case, in the operating region A on the low load and low rotation side, as described later, the intake of the intake air from the branch intake passage 16 is interrupted for the subsequent cylinders (second and third cylinders 2B and 2C), and from the preceding cylinder. Since excess air in the introduced gas is used for combustion, air necessary for combustion of fuel for the preceding and subsequent two cylinders is supplied to the preceding cylinders (first and fourth cylinders 2A and 2D). In addition, the throttle opening is adjusted.
[0056]
The fuel injection control means 44 controls the fuel injection amount and injection timing from the fuel injection valve 9 provided in each of the cylinders 2A to 2D in accordance with the operating state of the engine. The fuel injection control is changed depending on whether the vehicle is in the operation region A or the operation region B.
[0057]
That is, when the operating state is in the operating region A on the low load and low rotation side, the air-fuel ratio is higher than the stoichiometric air-fuel ratio, preferably the air-fuel ratio for the preceding cylinders (first, fourth cylinders 2A, 2D), preferably Controls the fuel injection amount so as to be approximately twice or more than the theoretical air-fuel ratio, and sets the injection timing so that the fuel is injected in the compression stroke to cause stratified combustion. On the other hand, for the subsequent cylinders (second and third cylinders 2B and 2C), the fuel injection amount is set so that the fuel is supplied to the burned gas having a lean air-fuel ratio introduced from the preceding cylinder to obtain the stoichiometric air-fuel ratio. In addition to the control, the injection timing is set so that ignition and combustion are possible in a situation where there is a large amount of burned gas.
[0058]
The fuel injection amount is controlled by the air flow sensor 19 and the O 2 This is performed by feedback control based on the output from the sensor 23 or the like. Specifically, the basic injection amount for each cylinder is calculated according to the intake air amount detected by the airflow sensor 19 so that the preceding cylinder has a predetermined lean air-fuel ratio and the succeeding cylinder has a stoichiometric air-fuel ratio. The linear O provided in the inter-cylinder gas passage 22 2 The fuel injection amount for the preceding cylinder is feedback-corrected based on the output from the sensor 25, and the O provided in the exhaust passage 20 is further corrected. 2 Based on the output from the sensor 23, the fuel injection amount for the subsequent cylinder is feedback-corrected.
[0059]
Further, when the operation state is in the operation region B on the high load side or high rotation side, the fuel injection amount is controlled so that the air-fuel ratio of each of the cylinders 2A to 2D is equal to or lower than the theoretical air-fuel ratio. The stoichiometric air-fuel ratio is set in most of the operating range B, and is made richer than the stoichiometric air-fuel ratio in the fully open load and the operating range in the vicinity thereof. In this case, the injection timing is set so that uniform combustion is performed by injecting fuel to each of the cylinders 2A to 2D in the intake stroke.
[0060]
The operation of the apparatus of the present embodiment as described above will be described with reference to FIGS.
[0061]
In the operating region A on the low load and low rotation side, the first exhaust valve 32a and the first intake valve 31a are stopped and the second exhaust valve 32b and the second intake valve 31b are activated as described above. A typical flow path of fresh air and gas is as shown in FIG. 6, and the burned gas discharged from the preceding cylinders (first and fourth cylinders) 2A, 2D is directly passed through the inter-cylinder gas passage 22 to the succeeding cylinder. (Cylinder No. 2 and No. 3) Two-cylinder connection that is introduced into 2B and 2C and that only burned gas discharged from the subsequent cylinders 2B and 2C is led to the exhaust passage 20 provided with the three-way catalyst 24 State.
[0062]
In this state, fresh air is introduced into the preceding cylinders 2A and 2D from the intake passage 15 during the intake stroke (arrow a in FIG. 6), and linear O is detected in the preceding cylinders 2A and 2D. 2 Fuel is injected in the compression stroke while the fuel injection amount is feedback-controlled so that the air-fuel ratio detected by the sensor 25 becomes a predetermined lean air-fuel ratio, and ignition is performed at a predetermined ignition timing. Stratified combustion is performed (see FIG. 5).
[0063]
Thereafter, burned gas discharged from the preceding cylinders 2A and 2D is introduced into the succeeding cylinders 2B and 2C through the gas passage 22 during a period in which the intake strokes of the preceding cylinders 2A and 2D overlap with the exhaust strokes of the succeeding cylinders 2B and 2C. (The white arrow in FIG. 5 and the arrow b in FIG. 6). In the succeeding cylinders 2B and 2C, the fuel is supplied to the burned gas having the lean air-fuel ratio introduced from the preceding cylinders 2A and 2D so that the stoichiometric air-fuel ratio is obtained. 2 While the fuel injection amount is controlled based on the output of the sensor 23, fuel is injected at an appropriate timing (for example, a compression stroke), and ignition is performed at a predetermined ignition timing to perform combustion (see FIG. 5). The burned gas after combustion in the succeeding cylinders 2B and 2C is discharged to the exhaust passage 20 provided with the three-way catalyst 24 (arrow c in FIG. 6).
[0064]
Thus, in the preceding cylinders 2A and 2D, the stratified combustion at the lean air-fuel ratio is performed, so that the thermal efficiency is increased and the pumping loss is reduced, and the fuel efficiency is greatly improved by the synergistic effect thereof. Further, in the succeeding cylinders 2B and 2C, fuel is supplied to the burned gas in an excess air state and combustion is performed while being controlled to the stoichiometric air-fuel ratio, so that stratified combustion is performed at a lean air-fuel ratio like the preceding cylinders 2A and 2D. Although the thermal efficiency is somewhat inferior to that performed, the fuel efficiency improvement effect by reducing the pumping loss can be sufficiently obtained.
[0065]
Moreover, since the gas discharged from the succeeding cylinders 2B and 2C into the exhaust passage 20 has a stoichiometric air-fuel ratio, it is not necessary to provide a lean NOx catalyst as in a conventional lean burn engine, and the three-way catalyst 24 is sufficient to exhaust the gas. Purification performance is ensured.
[0066]
Since there is no need to provide a lean NOx catalyst, there is no need to temporarily enrich the air-fuel ratio for NOx release and reduction when the NOx storage amount of the lean NOx catalyst is increased, thereby reducing fuel consumption improvement. can avoid. Furthermore, the problem of sulfur poisoning of the lean NOx catalyst does not occur.
[0067]
The preceding cylinders 2A and 2D have a lean air-fuel ratio that is approximately twice or more than the stoichiometric air-fuel ratio, so that the amount of NOx generated is relatively small. In the succeeding cylinders 2B and 2C, the preceding cylinders 2A and 2D Since the burned gas is introduced, the state is equivalent to that in which a large amount of EGR is performed, so that the generation of NOx is sufficiently suppressed. This is also advantageous for improving emissions.
[0068]
Further, the burned gas from the preceding cylinders 2A and 2D is introduced into the succeeding cylinders 2B and 2C through the inter-cylinder gas passage 22, and the heat radiation amount is adjusted by adjusting the passage length in the inter-cylinder gas passage 22 and the like. Thus, the temperature of the burned gas introduced into the succeeding cylinders 2B and 2C can be adjusted. In addition, by adjusting the temperature of the burned gas in this way and appropriately adjusting the fuel injection timing for the subsequent cylinders 2B and 2C, the subsequent cylinders 2B and 2C into which a large amount of burned gas is introduced are also ignited, Good combustibility can be maintained.
[0069]
Note that if the ratio of excess oxygen in the gas introduced from the preceding cylinders 2A and 2D to the succeeding cylinders 2B and 2C decreases, the combustion stability in the succeeding cylinders 2B and 2C is impaired. If the lean air-fuel ratio is approximately twice or more than the fuel ratio, combustion stability in the succeeding cylinders 2B and 2C is secured.
[0070]
On the other hand, in the operating region B on the high load side or the high rotation side, as described above, the first exhaust valve 32a and the first intake valve 31a are in the operating state, and the second exhaust valve 32b and the second intake valve 31b are in the stopped state. As a result, the actual flow path of fresh air and gas is as shown in FIG. 7, and the intake ports 31 and 31a and the exhaust ports 12a and 12 of each cylinder 2A to 2D are substantially independent from the intake passage 15. Fresh air is introduced into the intake ports 31 and 31a of the respective cylinders 2A to 2D, and burned gas is discharged from the exhaust ports 31 and 31a of the respective cylinders 2A to 2D into the exhaust passage 20. In this case, the output performance is ensured by controlling the intake air amount and the fuel injection amount so that the stoichiometric air-fuel ratio or richer.
[0071]
In addition, the specific structure of the apparatus of this invention is not limited to the said embodiment, A various change is possible. Other embodiments are described below.
[0072]
(1) In the basic embodiment described above, the fuel injection timing for the succeeding cylinder is set to the compression stroke so that the succeeding cylinder performs stratified combustion at the stoichiometric air-fuel ratio, but as shown in FIG. For the subsequent cylinders, split injection (F1, F2) may be performed in two steps, an intake stroke and a compression stroke. In this way, it is possible to avoid excessive collection of fuel near the spark plug, and combustion is performed in a weakly stratified state.
[0073]
Further, in the case where ignitability can be ensured even when fuel is uniformly dispersed in the succeeding cylinder due to a sufficiently high temperature of burned gas introduced from the preceding cylinder to the succeeding cylinder, as shown in FIG. The fuel injection for the subsequent cylinder may be the intake stroke batch injection.
[0074]
(2) The intake / exhaust port and the gas passage between cylinders may be arranged as shown in FIG. That is, in this figure, the No. 1 and No. 4 cylinders 2A, 2D, which are the preceding cylinders, are provided with an intake port 11 on the left half side of the combustion chamber, and a first exhaust port 12a and a second exhaust gas on the right half side. A port 12b is provided, and the second and third cylinders 2B and 2C, which are the subsequent cylinders, are provided with a first intake port 11a and a second intake port 11b on the left half side of the combustion chamber and an exhaust on the right half side. A port 12 is provided. Further, the inter-cylinder gas passage 22 has both ends of the second exhaust port 12b of the preceding cylinders 2A and 2D and the second intake port 11b of the succeeding cylinders 2B and 2C in a state where the engine body is crossed in the direction orthogonal to the cylinder row direction. And connected to. Other configurations are the same as those of the embodiment shown in FIGS.
[0075]
{Circle around (3)} In the basic embodiment, the flow path switching means is configured using a valve stop mechanism, but the flow path switching means may be configured using an on-off valve provided in the passage as shown in FIG. 11.
[0076]
That is, in this figure, intake side on-off valves 48a and 49a are provided in the branch intake passages 16 leading to the first intake ports 11a of the second cylinder 2B and the third cylinder 2C, which are the subsequent cylinders, and the first cylinder 1 Exhaust-side on / off valves 48b and 49b are provided in the branch exhaust passages 21 leading to the first exhaust ports 12a of the No. 2 cylinder and the No. 4 cylinder 2D, and further between the No. 1 cylinder 2A and the No. 2 cylinder 2B and No. 4 Gas passage opening / closing valves 48c and 49c are provided in each inter-cylinder gas passage 22 between the cylinder 2D and the third cylinder 2C. These on-off valves 48a, 49a, 48b, 49b, 48c, and 49c can be switched between a state in which the respective passages are opened and a state in which they are blocked, and are operated by an actuator not shown in the drawing. Yes.
[0077]
Then, according to the control means (not shown), each of the on-off valves is operated as follows depending on whether the operation state is in the operation region A on the low load / low rotation side or the operation region B on the high load side or the high rotation side. To be controlled.
[0078]
Figure 0003711939
The switching operation at the time of switching the state of each on-off valve at the transition of the operating state between the operating areas A and B may be performed within the switchable period shown in FIG. In other words, if the state of each on-off valve is switched during a period in which the exhaust stroke and the intake stroke of a pair of cylinders overlap, the subsequent cylinder is introduced with a mixture of burned gas and fresh air from the preceding cylinder. Therefore, the on-off valves 48a, 48b, and 48c are switched within a period excluding the period in which the exhaust stroke of the first cylinder 2A and the intake stroke of the second cylinder 2B overlap, and the exhaust stroke of the fourth cylinder 2D The on-off valves 48a, 48b and 48c may be switched and operated within a period excluding a period where the intake stroke of the third cylinder 2C overlaps.
[0079]
Thus, the on-off valves 48a, 49a, 48b, 49b, 48c, 49c and the control means for controlling them constitute the flow path switching means.
[0080]
Further, the intake valve 31, the first and second exhaust valves 32a and 32b, the first and second intake valves 31a and 31b, and the exhaust valve 32 provided at the ports of the respective cylinders are all valve operating mechanisms not shown. Is always opened and closed. Control of fuel injection from each fuel injection valve 9 is the same as in the above embodiment.
[0081]
Reference numeral 50 denotes a throttle valve provided in the intake passage 15.
[0082]
Also in this embodiment, in the operation region A, the two cylinders are connected, super lean combustion is performed in the preceding cylinders 2A and 2D, and the burned gas discharged from the preceding cylinders passes through the inter-cylinder gas passage 22. The fuel is introduced into the succeeding cylinders 2B and 2C, the fuel is supplied to the burned gas having a lean air-fuel ratio in the succeeding cylinders 2B and 2C, and the combustion is performed in a state where the stoichiometric air-fuel ratio is achieved. Only the gas is introduced into the exhaust passage 20 provided with the three-way catalyst 24. On the other hand, in the operation region B, the intake ports and exhaust ports of the cylinders 2A to 2D are independent, and fresh air is introduced from the intake passage to the intake ports of the cylinders and exhausted from the exhaust ports of the cylinders. Gas is introduced into the exhaust passage 20. Thus, the same operation and effect as the basic embodiment can be obtained.
[0083]
Further, according to the flow path switching means as in the present embodiment, the structure becomes relatively simple, and the switching operation of the on-off valve at the time of shifting to the operating state is performed within the switchable period as shown in FIG. The switching timing is not required to be remarkably high, and control is easy.
[0084]
(4) The passage and the flow path switching means for each cylinder may be configured as shown in FIG.
[0085]
That is, in this figure, each of the cylinders 2A to 2D of the engine body has an intake port 51 and an exhaust port 52 opened, and the intake valve 53 and the exhaust valve 54 provided in these ports are operated by a valve operating mechanism not shown in the figure. It is always opened and closed. Branch intake passages 16A to 16D are connected to the intake ports 51 of the cylinders 2A to 2D, branch exhaust passages 21A to 21D are connected to the exhaust ports 52 of the cylinders 2A to 2D, and the preceding cylinders (Nos. 1 and 4). The inter-cylinder gas passage 55 is provided between the collection portion of the branch exhaust passages 21A and 21D for the second cylinder) 2A and 2D and the collection portion of the branch exhaust passages 21B and 21C for the subsequent cylinders (second and third cylinders) 2B and 2C. A first on-off valve 57 is provided in the inter-cylinder gas passage 55.
[0086]
Further, the collecting portion of the branch intake passages 16A and 16D for the preceding cylinders 2A and 2D is always in communication with the upstream portion of the intake passage, and the collecting portion of the branch intake passages 16B and 16C for the succeeding cylinders 2B and 2C and the upstream portion of the intake passage. A second opening / closing valve 57 for opening and closing the communication portion is provided at the communication portion therebetween. On the other hand, the collective portion of the branch exhaust passages 21B and 21C for the subsequent cylinders 2B and 2C always communicates with the downstream portion of the exhaust passage, and the collective portion of the branch exhaust passages 21A and 21D for the preceding cylinders 2A and 2D and the downstream portion of the exhaust passage. A third opening / closing valve 58 for opening and closing the communication portion is provided at the communication portion therebetween.
[0087]
Then, according to the control means (not shown), the on-off valves 56 and 57 are operated depending on whether the operation state is in the operation region A on the low load / low rotation side or in the operation region B on the high load side or high rotation side. , 58 are controlled as follows.
[0088]
Figure 0003711939
Thus, the on-off valves 56, 57, 58 and the control means for controlling them constitute a flow path switching means. Control of fuel injection from each fuel injection valve 9 is the same as in the above embodiment.
[0089]
Also in this embodiment, in the operation region A, the burned gas discharged from the preceding cylinders 2A and 2D between the pair of cylinders in which the exhaust stroke and the intake stroke overlap is directly passed to the subsequent cylinders 2B and 2C via the inter-cylinder gas passage 55. In the two-cylinder connection state in which only the burned gas discharged from the succeeding cylinders 2B and 2C is led to the exhaust passage 20 provided with the three-way catalyst 24. The intake port 51 and the exhaust port 52 of each cylinder 2A to 2D are independent of each other, and fresh air is introduced from the intake passage to the intake port 51 of each cylinder, and the exhaust gas discharged from the exhaust port 52 of each cylinder is It will be guided to the exhaust passage 20.
[0090]
(5) As described above, when ignitability can be ensured even if fuel is uniformly dispersed in the succeeding cylinders 2B and 2C, the fuel injection valve provided in the succeeding cylinders 2B and 2C does not necessarily inject fuel directly into the combustion chamber. For example, as shown in FIG. 14, a fuel injection valve 9 ′ for supplying fuel to the succeeding cylinders 2B and 2C is provided in the intake passages of the succeeding cylinders 2B and 2C constituting the inter-cylinder gas passage. It may be provided. In this case, in the succeeding cylinders 2B and 2C, uniform combustion is performed by injecting fuel from the fuel injection valve 9 'in the intake stroke while maintaining the stoichiometric air-fuel ratio.
[0091]
In this way, the gas introduced into the succeeding cylinders 2B and 2C from the preceding cylinders 2A and 2D is appropriately dissipated, and this gas is contained in an ideal amount of EGR gas in which excess air and burned gas are mixed. Fuel is supplied in the process of being introduced into the succeeding cylinders 2B and 2C, fuel vaporization and further mixing with the gas are improved, and a large amount of EGR is performed in the succeeding cylinders 2B and 2C, and the combustibility is further improved. To do.
[0092]
(6) A turbocharger may be provided in addition to the structure as shown in the above embodiments, for example, a turbocharger 60 as shown in FIG. 15 may be provided. In the figure, a turbocharger 60 has a turbine 61 provided in the exhaust passage 20 and a compressor 62 provided in the intake passage 15, and the turbine 61 is driven by the energy of the exhaust gas flowing through the exhaust passage 20. The intake air is supercharged by the rotation of the compressor 62 that rotates in conjunction with the rotation. An intercooler 63 is provided in the intake passage 15 downstream of the compressor 62.
[0093]
In this way, it is possible to improve the fuel consumption in the two-cylinder connected state up to a relatively high load side.
[0094]
(7) In each of the above-described embodiments, the fresh air is changed depending on whether the operation state is in the operation region A on the low load / low rotation side or the operation region B on the high load side / high rotation side by the flow path switching means. In addition, the gas flow path is switched, but the fresh air and gas flow paths may be in the above-described two-cylinder connection state over the entire operation region.
[0095]
(8) The apparatus of the present invention can be applied to multi-cylinder engines other than four-cylinder engines. For example, in the case of six cylinders, the exhaust stroke of one cylinder and the intake stroke of another cylinder do not completely overlap. In such a case, the exhaust stroke of one cylinder precedes the intake stroke of the other cylinder. In addition, two cylinders in which both strokes partially overlap may be used as a pair of preceding and succeeding cylinders.
[0096]
(9) In addition to the structures shown in the above embodiments, EGR may be performed only for the preceding cylinder. In this way, the generation of NOx in the preceding cylinder is suppressed, and the burned gas introduced from the preceding cylinder suppresses the generation of NOx in the subsequent cylinder as in the case of EGR, so that NOx can be effectively reduced.
[0097]
【The invention's effect】
As described above, the control device of the present invention allows the burned gas discharged from the preceding cylinder in the exhaust stroke between the pair of cylinders in which the exhaust stroke and the intake stroke overlap to be directly transferred to the subsequent cylinder in the intake stroke via the inter-cylinder gas passage. Only the burned gas discharged from the subsequent cylinder is introduced into the exhaust passage provided with the three-way catalyst, and the preceding cylinder is burned in a lean air-fuel ratio. Since fuel is supplied to the burned gas having a lean air-fuel ratio introduced from the preceding cylinder and combustion is performed in a state where the stoichiometric air-fuel ratio is set, the thermal efficiency is improved by the lean combustion in the preceding cylinder and the pumping loss is reduced. By reducing the pumping loss in the subsequent cylinders, etc., the fuel efficiency is greatly improved, and a sufficient exhaust purification action can be provided with only a three-way catalyst. Accordingly, the lean NOx catalyst is not required, the cost is reduced, and it is not necessary to perform enrichment of the air-fuel ratio temporarily during lean operation. The problem of catalyst sulfur poisoning can also be eliminated.
[0098]
Moreover, since the high-temperature burned gas discharged from the preceding cylinder is introduced into the succeeding cylinder through the inter-cylinder gas passage, the gas temperature can be adjusted by heat radiation in the inter-cylinder gas passage, and the air Excess burnt gas can be sufficiently mixed, thereby improving the combustibility in the succeeding cylinder.
[Brief description of the drawings]
FIG. 1 is a schematic plan view of an entire engine including an apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of an engine body and the like.
FIG. 3 is a block diagram of a control system.
FIG. 4 is an explanatory diagram showing an operation region.
FIG. 5 is a diagram showing an exhaust stroke, an intake stroke, a fuel injection timing, an ignition timing, and the like of each cylinder.
FIG. 6 is an explanatory diagram showing substantial fresh air and gas flow paths during low load and low rotation.
FIG. 7 is an explanatory diagram showing a substantial fresh air and gas flow path when in an operation region on a high load, high and low rotation side.
FIG. 8 is a diagram showing another example of the fuel injection timing of the succeeding cylinder.
FIG. 9 is a diagram showing still another example of the fuel injection timing of the subsequent cylinder.
FIG. 10 is a schematic plan view showing another embodiment of the configuration of an intake / exhaust port, an inter-cylinder gas passage, and the like.
FIG. 11 is a schematic plan view showing another embodiment of the distribution path switching means and the like.
12 is an explanatory diagram showing a switchable period of the on-off valve when shifting to an operation state in the case of the embodiment of FIG.
FIG. 13 is a schematic plan view showing still another embodiment of the distribution path switching means and the like.
FIG. 14 is a schematic plan view showing an embodiment in which a fuel injection valve is provided in an intake passage of a subsequent cylinder.
FIG. 15 is a schematic plan view showing an embodiment provided with a turbocharger.
[Explanation of symbols]
1 Engine body
2A to 2D cylinder
9 Fuel injection valve
11 Intake port
11a First intake port
11b Second intake port
12 Exhaust port
12a First exhaust port
12b Second exhaust port
15 Intake passage
20 Exhaust passage
22 Gas passage between cylinders
24 Three-way catalyst
31 Intake valve
31a First intake valve
31b Second intake valve
32 Exhaust valve
32a First exhaust valve
32b Second exhaust valve
35 Valve stop mechanism
40 ECU
41 Operating state discriminating means
42 Valve stop mechanism control means
43 Intake air amount control means
44 Fuel injection control means

Claims (10)

各気筒が所定の位相差をもって吸気、圧縮、膨張、排気の各行程からなるサイクルを行うようになっている多気筒の火花点火式エンジンにおいて、
少なくとも低負荷低回転域で、排気行程と吸気行程が重なる一対の気筒間において排気行程側の気筒である先行気筒から排出される既燃ガスがそのまま吸気行程側の気筒である後続気筒に気筒間ガス通路を介して導入され、この後続気筒から排出されるガスのみが三元触媒を備えた排気通路に導かれるような２気筒接続状態にガス流通経路を構成するとともに、
上記２気筒接続状態にあるときに、上記先行気筒では理論空燃比よりも所定量大きいリーン空燃比とした状態で燃焼を行わせ、上記後続気筒では、先行気筒から導入されたリーン空燃比の既燃ガスに燃料を供給して理論空燃比とした状態で燃焼を行わせるように、各気筒に対する燃料供給を制御する制御手段を備えたことを特徴とする火花点火式エンジンの制御装置。In a multi-cylinder spark ignition engine in which each cylinder performs a cycle consisting of intake, compression, expansion, and exhaust strokes with a predetermined phase difference,
At least in the low load and low rotation range, between the pair of cylinders where the exhaust stroke and the intake stroke overlap, the burned gas discharged from the preceding cylinder which is the cylinder on the exhaust stroke side is directly between the cylinders in the subsequent cylinder which is the cylinder on the intake stroke side The gas flow path is configured in a two-cylinder connection state in which only the gas introduced through the gas passage and exhausted from the subsequent cylinder is guided to the exhaust passage provided with the three-way catalyst,
When the two cylinders are connected, combustion is performed in a state where the preceding cylinder has a lean air-fuel ratio that is a predetermined amount larger than the stoichiometric air-fuel ratio, and in the succeeding cylinder, the lean air-fuel ratio already introduced from the preceding cylinder is reduced. A control device for a spark ignition type engine, comprising control means for controlling fuel supply to each cylinder so that combustion is performed in a state where a fuel is supplied to a fuel gas to have a stoichiometric air-fuel ratio. 排気行程と吸気行程とが完全に重なり合う２つの気筒、または一方の気筒の排気行程が他方の気筒の吸気行程より先行するとともに両行程が部分的に重なり合う２つの気筒を先行、後続の一対の気筒とすることを特徴とする請求項１記載の火花点火式エンジンの制御装置。Two cylinders in which the exhaust stroke and the intake stroke completely overlap, or a pair of cylinders that precede and follow the two cylinders in which the exhaust stroke of one cylinder precedes the intake stroke of the other cylinder and both strokes partially overlap The control device for a spark ignition engine according to claim 1, wherein: 上記２気筒接続状態にあるときの当該先行気筒の空燃比を理論空燃比の略２倍もしくはそれ以上としたことを特徴とする請求項１または２記載の火花点火式エンジンの制御装置。3. The spark ignition engine control apparatus according to claim 1, wherein the air-fuel ratio of the preceding cylinder in the two-cylinder connected state is approximately twice or more than the theoretical air-fuel ratio. 高負荷、高回転側の運転領域では各気筒の吸気ポートと排気ポートとを独立させて、吸気通路から各気筒の吸気ポートに新気を導入するとともに各気筒の排気ポートから排出される排気ガスを上記排気通路に導くように新気及びガスの流通経路を切換える流通経路切換手段を備え、
上記制御手段は上記高負荷、高回転側の運転領域で各気筒の空燃比を理論空燃比もしくはそれ以下とするようにしたことを特徴とする請求項１乃至３のいずれかに記載の火花点火式エンジンの制御装置。Exhaust gas exhausted from the exhaust port of each cylinder while introducing fresh air from the intake passage to the intake port of each cylinder by making the intake port and exhaust port of each cylinder independent in the operating region on the high load and high rotation side A flow path switching means for switching the flow path of fresh air and gas so as to guide the air to the exhaust passage,
The spark ignition according to any one of claims 1 to 3, wherein the control means sets the air-fuel ratio of each cylinder to the stoichiometric air-fuel ratio or less in the operating region on the high load and high rotation side. Type engine control device. 上記先行気筒に、上記吸気通路に通じる吸気ポートと、上記排気通路に通じる第１排気ポートと、気筒間ガス通路に通じる第２排気ポートとを設ける一方、上記後続気筒に、上記吸気通路に通じる第１吸気ポートと、上記気筒間ガス通路に通じる第２吸気ポートと、上記排気通路に通じる排気ポートとを設け、
上記流通経路切換手段として、上記先行気筒の第１，第２排気ポートを開閉する第１，第２排気弁および後続気筒の第１，第２吸気ポートを開閉する第１，第２吸気弁をそれぞれ作動状態と停止状態とに切換える弁停止機構と、低負荷低回転域では上記第１排気弁および上記第１吸気弁を停止状態、上記第２排気弁および上記第２吸気弁を作動状態とし、高負荷、高回転側の運転領域では上記第１排気弁および上記第１吸気弁を作動状態、上記第２排気弁および上記第２吸気弁を停止状態とする弁停止機構制御手段とを備えたことを特徴とする請求項４記載の火花点火式エンジンの制御装置。The preceding cylinder is provided with an intake port that communicates with the intake passage, a first exhaust port that communicates with the exhaust passage, and a second exhaust port that communicates with an inter-cylinder gas passage, while the subsequent cylinder communicates with the intake passage. A first intake port, a second intake port that communicates with the inter-cylinder gas passage, and an exhaust port that communicates with the exhaust passage;
The flow path switching means includes first and second exhaust valves that open and close the first and second exhaust ports of the preceding cylinder and first and second intake valves that open and close the first and second intake ports of the subsequent cylinder. A valve stop mechanism for switching between an operating state and a stopped state, and in the low load and low rotation range, the first exhaust valve and the first intake valve are stopped, and the second exhaust valve and the second intake valve are operated. And a valve stop mechanism control means for operating the first exhaust valve and the first intake valve and stopping the second exhaust valve and the second intake valve in an operating region on the high load and high rotation side. The control device for a spark ignition engine according to claim 4, wherein the control device is a spark ignition engine. 三元触媒を備えた排気通路に理論空燃比検出用の排気ガス濃度検出手段を設けるとともに、気筒間ガス通路にリーン空燃比検出用の排気ガス濃度検出手段を設け、
上記制御手段は、上記２気筒接続状態にあるときに上記各排気ガス濃度検出手段による検出値に基き、先行気筒を理論空燃比よりも所定量大きいリーン空燃比とするとともに後続気筒を理論空燃比とするように各気筒に対する燃料噴射量をフィードバック制御するようにしたことを特徴とする請求項１乃至５のいずれかに記載の火花点火式エンジンの制御装置。An exhaust gas concentration detection means for detecting the stoichiometric air-fuel ratio is provided in the exhaust passage provided with the three-way catalyst, and an exhaust gas concentration detection means for detecting a lean air-fuel ratio is provided in the inter-cylinder gas passage.
The control means sets the preceding cylinder to a lean air-fuel ratio that is a predetermined amount larger than the stoichiometric air-fuel ratio and sets the succeeding cylinder to the stoichiometric air-fuel ratio based on the detection value by each exhaust gas concentration detecting means when the two-cylinder is connected. 6. The control device for a spark ignition engine according to claim 1, wherein the fuel injection amount for each cylinder is feedback controlled. 上記先行気筒に対して筒内に直接燃料を噴射する燃料噴射弁を設け、
上記制御手段は、上記２気筒接続状態にあるときに、先行気筒においてはリーン空燃比としつつ上記燃料噴射弁から圧縮行程で燃料を噴射することにより成層燃焼を行わせるようにしたことを特徴とする請求項１乃至６のいずれかに記載の火花点火式エンジンの制御装置。A fuel injection valve for directly injecting fuel into the cylinder with respect to the preceding cylinder is provided,
The control means is characterized in that stratified combustion is performed by injecting fuel from the fuel injection valve in a compression stroke while maintaining a lean air-fuel ratio in the preceding cylinder when the two-cylinder connection state is established. The control device for the spark ignition engine according to any one of claims 1 to 6. 後続気筒に対して筒内に直接燃料を噴射する燃料噴射弁を設け、
上記制御手段は、上記２気筒接続状態にあるときに、後続気筒においては理論空燃比としつつ上記燃料噴射弁から少なくとも燃料の一部を圧縮行程で噴射することにより成層燃焼を行わせるようにしたことを特徴とする請求項７記載の火花点火式エンジンの制御装置。A fuel injection valve that directly injects fuel into the cylinder with respect to the subsequent cylinder is provided,
The control means is configured to perform stratified combustion by injecting at least a part of the fuel from the fuel injection valve in the compression stroke while maintaining the stoichiometric air-fuel ratio in the succeeding cylinder when the two-cylinder connection state is established. The control device for a spark ignition engine according to claim 7. 上記制御手段は、上記２気筒接続状態にあるときに、後続気筒においては理論空燃比としつつ均一燃焼を行わせるようにしたことを特徴とする請求項７記載の火花点火式エンジンの制御装置。8. The spark ignition engine control apparatus according to claim 7, wherein the control means is configured to perform uniform combustion while maintaining the stoichiometric air-fuel ratio in the succeeding cylinder when the two cylinders are connected. 気筒間ガス通路を構成する後続気筒の吸気通路に、後続気筒に燃料を供給する燃料噴射弁を設け、
上記制御手段は、上記２気筒接続手段にあるときに、後続気筒においては理論空燃比としつつ上記燃料噴射弁から吸気行程で燃料を噴射することにより均一燃焼を行わせるようにしたことを特徴とする請求項７記載の火花点火式エンジンの制御装置。A fuel injection valve for supplying fuel to the succeeding cylinder is provided in the intake passage of the succeeding cylinder constituting the inter-cylinder gas passage,
The control means is characterized in that when in the two-cylinder connection means, uniform combustion is performed by injecting fuel in the intake stroke from the fuel injection valve while maintaining the stoichiometric air-fuel ratio in the subsequent cylinder. The spark ignition engine control device according to claim 7.
JP2002024548A 2002-01-31 2002-01-31 Control device for spark ignition engine Expired - Fee Related JP3711939B2 (en)

Priority Applications (13)

Application Number Priority Date Filing Date Title
JP2002024548A JP3711939B2 (en) 2002-01-31 2002-01-31 Control device for spark ignition engine
KR10-2003-7014146A KR20040074592A (en) 2002-01-31 2003-01-31 Spark ignition engine control device
US10/472,563 US7219634B2 (en) 2002-01-31 2003-01-31 Spark ignition engine control device
DE60300437T DE60300437T2 (en) 2002-01-31 2003-01-31 DEVICE FOR REGULATING A RADIATED INTERNAL COMBUSTION ENGINE
EP03703109A EP1362176B1 (en) 2002-01-31 2003-01-31 Spark ignition engine control device
EP03703108A EP1366279B1 (en) 2002-01-31 2003-01-31 Control device for spark-ignition engine
CNB03802487XA CN100368671C (en) 2002-01-31 2003-01-31 Spark ignition engine control device
PCT/JP2003/000962 WO2003064838A1 (en) 2002-01-31 2003-01-31 Spark ignition engine control device
KR10-2003-7014141A KR20040074591A (en) 2002-01-31 2003-01-31 Control device for spark-ignition engine
US10/472,523 US7182050B2 (en) 2002-01-31 2003-01-31 Control device for spark-ignition engine
DE60309098T DE60309098T8 (en) 2002-01-31 2003-01-31 DEVICE FOR REGULATING A RADIATED INTERNAL COMBUSTION ENGINE
PCT/JP2003/000961 WO2003064837A1 (en) 2002-01-31 2003-01-31 Control device for spark-ignition engine
CNB038024594A CN100363609C (en) 2002-01-31 2003-01-31 Spark ignition engine control device

Applications Claiming Priority (1)

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JP2002024548A JP3711939B2 (en) 2002-01-31 2002-01-31 Control device for spark ignition engine

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JP2003227383A JP2003227383A (en) 2003-08-15
JP3711939B2 true JP3711939B2 (en) 2005-11-02

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3956783B2 (en) 2002-07-02 2007-08-08 マツダ株式会社 Control device for spark ignition engine
JP4259255B2 (en) 2003-09-30 2009-04-30 マツダ株式会社 Control device for spark ignition engine
JP2007085304A (en) * 2005-09-26 2007-04-05 Yamaha Motor Co Ltd Engine system and vehicle having the same
WO2013172973A2 (en) * 2012-05-18 2013-11-21 Lippitt Raymond F Internal combustion engines

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