JP3744112B2

JP3744112B2 - Engine fuel control device

Info

Publication number: JP3744112B2
Application number: JP07537697A
Authority: JP
Inventors: 誠二浅野
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1997-03-27
Filing date: 1997-03-27
Publication date: 2006-02-08
Anticipated expiration: 2017-03-27
Also published as: JPH10266883A

Description

【０００１】
【発明の属する技術分野】
本発明は、エンジンの燃料制御装置に関し、特に燃料消費を低減させるエンジンの制御方法に関する。
【０００２】
【従来の技術】
従来の技術といえば、特開昭58−48749 号記載のように、排気ガス中の酸素濃度から、理論空燃比近傍及び燃料リーン空燃比域における混合気の空燃比を感知する空燃比センサと、混合気の空燃比を制御する空燃比制御手段とを用い、前記空燃比センサの出力に基づいて、混合気の空燃比が理論空燃比及び燃料リーン空燃比域の目標空燃比となるよう、前記空燃制御を帰還制御することが記載されている。
【０００３】
【発明が解決しようとする課題】
前記のような従来技術は、燃料リーン空燃比域での排気有害成分（特に窒素酸化物）について考慮されておらず、燃料リーン空燃比域においては、燃焼温度が上昇するため、このときの排気ガス成分中には、理論空燃比制御領域よりも多く窒素酸化物が含まれている。
【０００４】
したがって、燃料消費を低減させるための燃料リーン空燃比域がかなり限定されてくる。
【０００５】
本発明は、このような問題に鑑みてなされたものであって、その目的とするところは、エンジンを燃料リーン空燃比域での運転で燃料消費を低減し、且つ排気ガス成分中の窒素酸化物を低減するエンジンの燃料制御装置を提供することにある。
【０００６】
【課題を解決するための手段】
前記目的は、
エンジンの吸入空気量計測手段と、
エンジンの回転数検出手段と、
エンジンの所定のクランク角度を得る手段と、
前記エンジンの吸入空気量計測手段で計測された吸入空気量と、前記エンジンの回転数検出手段で検出された回転数から、エンジンに供給する基本的な燃料量を得る手段と、
エンジンの排出する排気ガスの酸素濃度を検出する手段と、
前記検出された酸素濃度に基づいて、前記基本的な燃料量を目標とする空燃比を得られるよう補正し、第１の燃料量を得る手段と、
前記第１の燃料量をもとに理論空燃比より濃い第２の燃料量を得る手段と、
前記第１の燃料量をもとに理論空燃比より希薄な第３の燃料量を得る手段と、
エンジンの状態に応じて前記第１の燃料量を供給する領域と、第２の燃料量と第３の燃料量の燃料を噴射するタイミングに応じて切り替えて供給する領域を有する手段と、
前記得られた所定のクランク角度で前記の領域とタイミングに応じて供給される燃料量をエンジンに噴射する手段を有すると共に、前記第２の燃料量と第３の燃料量を切り替えて供給する領域においては、領域内の平均空燃比が理論空燃比よりも希薄側とすることを特徴とするエンジンの燃料制御装置によって達成される。
また、上記目的は、
エンジンの吸入空気量計測手段と、
エンジンの回転数検出手段と、
エンジンの所定のクランク角度を得る手段と、
前記エンジンの吸入空気量計測手段で計測された吸入空気量と、前記エンジンの回転数検出手段で検出された回転数から、エンジンに供給する基本的な燃料量を得る手段と、
エンジンの排出する排気ガスの酸素濃度を検出する手段と、
前記検出された酸素濃度に基づいて、前記基本的な燃料量を目標とする空燃比を得られるよう補正し、第１の燃料量を得る手段と、
前記第１の燃料量をもとに理論空燃比より濃い第２の燃料量を得る手段と、
前記第１の燃料量をもとに理論空燃比より希薄な第３の燃料量を得る手段と、
エンジンの状態に応じて前記第１の燃料量を供給する領域と、第２の燃料量と第３の燃料量の燃料を、噴射するタイミングに応じて切り替えて供給する領域を有する手段と、
前記得られた所定のクランク角度で前記の領域とタイミングに応じて供給される燃料量をエンジンに噴射する手段とを有すると共に、前記第２の燃料量と第３の燃料量を切り替えるタイミングは、予め定められた噴射回数毎に切り替えることを特徴とするエンジンの燃料制御装置によっても達成される。
また、上記目的は、
エンジンの吸入空気量計測手段と、
エンジンの回転数検出手段と、
エンジンの所定のクランク角度を得る手段と、
前記エンジンの吸入空気量計測手段で計測された吸入空気量と、前記エンジンの回転数検出手段で検出された回転数から、エンジンに供給する基本的な燃料量を得る手段と、
エンジンの排出する排気ガスの酸素濃度を検出する手段と、
前記検出された酸素濃度に基づいて、前記基本的な燃料量を目標とする空燃比を得られるよう補正し、第１の燃料量を得る手段と、
前記第１の燃料量をもとに理論空燃比より濃い第２の燃料量を得る手段と、
前記第１の燃料量をもとに理論空燃比より希薄な第３の燃料量を得る手段と、
エンジンの状態に応じて前記第１の燃料量を供給する領域と、第２の燃料量と第３の燃料量の燃料を、噴射するタイミングに応じて切り替えて供給する領域を有する手段と、
前記得られた所定のクランク角度で前記の領域とタイミングに応じて供給される燃料量をエンジンに噴射する手段とを有すると共に、前記第２の燃料量と第３の燃料量を切り替えるタイミングは、予め定められたパターンに応じて切り替えることを特徴とするエンジンの燃料制御装置によっても達成される。
【０００７】
【発明の実施の形態】
以下、図面により本発明の一実施の形態について説明する。
【０００８】
図１は、本実施の形態のエンジン及び該エンジンの制御装置の全体構成を示したものである。エンジン１００には、エンジン１００の吸入する空気量を発熱体抵抗で計測する発熱体抵抗式空気流量計（以下、Ｈ／Ｗセンサと云う）１０１，エンジン１００の吸入する空気流量を調整するスロットル絞り弁１０３，該スロットル絞り弁１０３の開度を電気的信号に変換するスロットル開度センサ１０２、及び、与えられた電気的信号でエンジン１００に燃料を供給する燃料噴射弁１０４が配置されるとともに、前記エンジン１００には、与えられた電気的信号及びタイミングでシリンダ内の燃料と空気の混合気を点火する点火栓１０５，エンジンのクランク軸の円周上に設置されて単位時間当たりの回転数を計測するクランク角度センサ１０６が設置されている。前記エンジン１００の排気管には、排気ガス中の酸素濃度を検出してエンジン１００を目標の空燃比の燃料噴射量とする帰還制御のための電気的信号を発生する酸素濃度センサ１０７，前記酸素濃度センサ１０７の下流に排気ガスを酸化，還元し浄化する酸化還元触媒１０８が設置されるとともに、更にエンジン１００には前記Ｈ／Ｗセンサ１０１，前記クランク角度センサ１０６，前記酸素濃度センサ１０７の電気的信号を予め定められた手順に基づいて処理し、エンジン１００の要求する燃料量，点火時期を決定し、前記燃料噴射弁等のアクチュエータに電気的信号を送るエンジンの制御装置１０９が配置されている。
【０００９】
図２は、本実施の形態のエンジンの制御装置の一例を示したものである。該エンジン制御装置１０９は、エンジン１００の各部に設置されたセンサ類からの信号を入力し、小信号（ＴＴＬレベル）をアクチュエータ駆動の大信号に変換するドライバ回路２０１，入出力信号をデジタル演算処理を行えるようアナログ−デジタル信号変換を行う入出力回路２０２，デジタル演算処理を行うマイクロコンピュータ、もしくはそれに準ずる演算回路を保有する演算回路２０３，演算回路２０３の演算処理に用いる定数及びプログラムを格納する不揮発性メモリ２０４，変数を格納する揮発性メモリ２０５，演算回路２０３のメモリ及び揮発性メモリ２０５の内容を保持するための電源保持回路（バックアップ）２０６から構成されている。尚、本実施例では入出力回路２０２と演算回路２０３を分離して記述しているが、演算回路２０３が入出力回路２０２を含んでいることもある。また本実施例のエンジンの制御装置は、Ｈ／Ｗセンサ，酸素濃度センサ，クランク角度センサ，スロットル開度センサ，水温センサ、の電気的信号が入力され、燃料噴射弁，点火栓の駆動信号を出力している。
【００１０】
図３は、本実施のエンジンの空燃比（ガソリンと空気の混合比）と排出される未燃焼ガソリン（ＨＣ）３０１，窒素酸化物（ＮＯｘ）３０２、及び燃料消費率３０３の関係を示している。理論空燃比に対して空燃比がリッチ側ではＨＣが多く排出され、理論空燃比よりリーン側になると急激に排出量は減少する。これに対してＮＯｘは理論空燃比よりリーンになるにつれて徐々に増加する。また、燃料消費率が最小となるところは理論空燃比より多少リーン側にあることを示している。
【００１１】
図４は、本発明の構成の燃料噴射の形態の１例である。実線４０１は実際に噴射している燃料噴射幅を示している。破線４０２は理論空燃比に保つのに必要な燃料噴射幅を示してる。従って、燃料噴射幅４０３は理論空燃比よりもリッチ側の燃料が噴射されており他の燃料噴射幅は理論空燃比よりもリーン側の燃料噴射幅がセットされている。チャート４０４はシリンダカウンタであり、燃料噴射タイミング毎にインクリメントされ所定の値４０５になるとリセットされている。このリセットされるタイミングにおいて前述の燃料噴射幅４０３の燃料噴射量がセットされるよう構成している。
【００１２】
図５は、本発明の構成の燃料噴射の形態の他の例である。前述の図４の構成に対して理論空燃比よりもリッチ側の燃料噴射幅がセットされるタイミングが、燃料噴射タイミング毎の燃料噴射パターンテーブルにしたがうよう構成されてる。図６は、前述の図４，図５の構成の燃料噴射形態を実行する領域を示している。領域６０１は前述の排気管に設置された酸素濃度センサの出力に基づいて空燃比のフィードバックを行う領域である。領域６０２は、前述の図４，図５の構成の燃料噴射形態を実行する領域（間欠リーン領域）である。領域６０３はパワー領域であり、理論空燃比よりもリッチな燃料噴射を行う領域である。
【００１３】
図７は、前述の酸素濃度センサ出力とフィードバック係数、及び前述の図４，図５の燃料噴射形態を行うときの空燃比補正係数の関係を示している。チャート７０１は前述の酸素濃度センサの出力であり、チャート７０２は酸素濃度センサ出力より計算された空燃比補正係数である。係数７０３は、加重平均もしくは移動平均等で計算された空燃比補正係数の平均値である。係数７０４は前述の空燃比補正係数平均値より計算された前述の図４，図５のリッチ側の燃料噴射幅を計算する係数、係数７０５はリーン側の燃料噴射幅を計算する係数である。
【００１４】
図８は、本発明の構成のエンジンの制御装置の燃料噴射のフローチャートを示している。ステップ８０１でＨ／Ｗセンサの出力を読み込む。ステップ８０２で前述のエンジンのクランク角度センサの信号から計算されるエンジン回転数を読み込む。ステップ８０３，８０４では前述のＨ／Ｗセンサ出力とエンジン回転数でエンジン負荷と基本燃料量を計算する。ステップ８０５では、前述のエンジン回転数とエンジン負荷で決定される燃料噴射形態を判断する。空燃比フィードバック領域であればステップ８０６，間欠リーン制御領域であればステップ８０７，パワー領域であればステップ８０８へ分岐しそれぞれの空燃比補正を行う。それぞれ補正された燃料はステップ８０９でセットされエンジンに実際噴射される。
【００１５】
図９は、前述の空燃比フィードバックのフローチャートを示している。ステップ９０１で前述の酸素濃度センサの出力を読み込む。ステップ９０２で前述の酸素濃度センサ出力が所定値より大きいかどうかを判断する。ステップ９０３，９０４，９０５は前述の酸素濃度センサの出力が所定値よりも大きい場合の処理でありフローに示しているように空燃比補正係数αｆに対して微分分，積分分のフィードバック補正を施す。ステップ９０６，９０７，９０８は前述の酸素濃度センサ出力が所定値よりも小さい場合のフィードバック補正である。
【００１６】
図１０は、前述の間欠リーン領域で用いる空燃比補正の係数の計算フローチャートである。ステップ１００１で空燃比補正係数αを読み込む。ステップ1002で前述の空燃比補正係数αｆの平均値αｆを計算する。ステップ１００３，1004でエンジン回転数，基本燃料量を読み込む。ステップ１００５，１００６で前述のエンジン回転数，基本燃料量のマップからリーン側燃料ゲインＫｌ，リッチ側燃料ゲインＫｒを検索する。ステップ１００７，１００８で前述のリーン，リッチ側燃料ゲイン，空燃比補正係数平均値αｆからリーン側燃料補正係数αｌ，リッチ側燃料補正係数αｒを計算する。
【００１７】
図１１は、前述の間欠リーンの燃料の補正フローチャートの一例である。本フローチャートはエンジンのクランク角度同期、特に燃料噴射量セット毎に実行される。ステップ１１０１でシリンダカウンタをインクリメントする。ステップ１１０２でシリンダカウンタが所定値以上かどうかを判断する。シリンダカウンタが所定値以上であれば、ステップ１１０３でリッチ側空燃比補正係数αｒ、所定値以下であれば、ステップ１１０４でリーン側空燃比補正係数αｌを読み込みステップ１１０５でシリンダカウンタをクリア（リセット）する。ステップ1106では、読み込まれた空燃比補正係数で基本燃料量を補正し間欠リーン制御を行う。
【００１８】
図１２は前述の間欠リーンの燃料補正フローチャートの他の例である。前述の図１１の例にたいしてリッチ燃料側補正係数、リーン側燃料補正係数の切り替えをステップ１２０１で間欠燃料噴射パターンテーブルを読み込むことで判断している。
【００１９】
以上、本発明の一実施の形態について示したが、前述の如く構成された本発明に係るエンジンの燃料制御装置は、理論空燃比に対して希薄側の燃料を噴射して燃料消費を低減する。このとき発生した窒素酸化物は排気管の下流に設置された酸化還元触媒内に一時貯えられるような状態となっており、このあとに噴射される理論空燃比よりも濃い燃料により還元し、外部への排出を低減するものである。
【００２０】
【発明の効果】
本実施の形態によれば、車両走行時の有害な排気成分（特に窒素酸化物）を増加させることなく燃料の消費量を減少させることができる。また、本発明の特徴の制御領域をエンジンの状態におうじてわけてあるので運転性を損なうこともない。
【図面の簡単な説明】
【図１】本発明の一実施例の形態のエンジン、及び該エンジン制御装置の構成図の一例。
【図２】本発明のエンジン制御装置の構成概念図の一例。
【図３】本発明のエンジンの空燃比と排気ガス成分、燃料消費率の相関図の一例。
【図４】本発明の燃料噴射形態の一例。
【図５】本発明の燃料噴射形態の他の例。
【図６】本発明の燃料噴射形態を実行する領域の例。
【図７】本発明の酸素濃度センサ出力とフィードバック係数、及び空燃比補正係数の相関図
【図８】本発明制御装置の燃料噴射フローチャートの一例。
【図９】本発明制御装置の空燃比フィードバックフローチャートの一例。
【図１０】本発明制御装置の間欠リーン領域において空燃比補正係数の計算フローチャートの一例。
【図１１】本発明制御装置の間欠リーン燃料補正のフローチャートの一例。
【図１２】本発明制御装置の間欠リーン燃料補正のフローチャートの他の例。
【符号の説明】
１００…エンジン、１０１…発熱体抵抗式空気流量計、１０４…燃料噴射弁、１０６…クランク角度センサ、１０７…酸素濃度センサ、１０９…エンジン制御装置。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine fuel control apparatus, and more particularly to an engine control method for reducing fuel consumption.
[0002]
[Prior art]
Speaking of the prior art, as described in JP-A-58-48749, from the oxygen concentration in the exhaust gas, an air-fuel ratio sensor that senses the air-fuel ratio of the air-fuel mixture in the vicinity of the theoretical air-fuel ratio and in the fuel-lean air-fuel ratio range, Air-fuel ratio control means for controlling the air-fuel ratio of the air-fuel mixture, and based on the output of the air-fuel ratio sensor, the air-fuel ratio of the air-fuel mixture becomes the stoichiometric air-fuel ratio and the target air-fuel ratio in the fuel lean air-fuel ratio region It describes that feedback control of air-fuel control is performed.
[0003]
[Problems to be solved by the invention]
The prior art as described above does not consider exhaust harmful components (particularly nitrogen oxides) in the fuel lean air-fuel ratio region, and the combustion temperature rises in the fuel lean air-fuel ratio region. The gas component contains more nitrogen oxide than in the theoretical air-fuel ratio control region.
[0004]
Therefore, the fuel lean air-fuel ratio region for reducing fuel consumption is considerably limited.
[0005]
The present invention has been made in view of such problems, and the object of the present invention is to reduce fuel consumption by operating the engine in a fuel lean air-fuel ratio region and to oxidize nitrogen in exhaust gas components. An object of the present invention is to provide a fuel control device for an engine that reduces the amount of matter.
[0006]
[Means for Solving the Problems]
The purpose is,
Engine intake air amount measuring means;
Engine speed detection means;
Means for obtaining a predetermined crank angle of the engine;
Means for obtaining a basic fuel amount to be supplied to the engine from the intake air amount measured by the intake air amount measuring means of the engine and the rotational speed detected by the engine speed detecting means;
Means for detecting the oxygen concentration of the exhaust gas discharged from the engine;
Based on the detected oxygen concentration, means for obtaining the first fuel amount by correcting the basic fuel amount so as to obtain a target air-fuel ratio;
Means for obtaining a second fuel amount that is richer than the stoichiometric air-fuel ratio based on the first fuel amount;
Means for obtaining a third fuel amount leaner than the stoichiometric air-fuel ratio based on the first fuel amount;
Means having a region for supplying the first fuel amount according to the state of the engine, and a region for switching and supplying according to the timing of injecting the fuel of the second fuel amount and the third fuel amount;
A region having means for injecting into the engine the amount of fuel supplied in accordance with the region and timing at the obtained predetermined crank angle, and a region for switching and supplying the second fuel amount and the third fuel amount Is achieved by an engine fuel control device characterized in that the average air-fuel ratio in the region is leaner than the stoichiometric air-fuel ratio.
The above purpose is
Engine intake air amount measuring means;
Engine speed detection means;
Means for obtaining a predetermined crank angle of the engine;
Means for obtaining a basic fuel amount to be supplied to the engine from the intake air amount measured by the intake air amount measuring means of the engine and the rotational speed detected by the engine speed detecting means;
Means for detecting the oxygen concentration of the exhaust gas discharged from the engine;
Based on the detected oxygen concentration, means for obtaining the first fuel amount by correcting the basic fuel amount so as to obtain a target air-fuel ratio;
Means for obtaining a second fuel amount that is richer than the stoichiometric air-fuel ratio based on the first fuel amount;
Means for obtaining a third fuel amount leaner than the stoichiometric air-fuel ratio based on the first fuel amount;
Means having a region for supplying the first fuel amount according to the state of the engine, and a region for switching and supplying the fuel of the second fuel amount and the third fuel amount according to the injection timing;
Means for injecting into the engine the amount of fuel supplied according to the region and timing at the obtained predetermined crank angle, and the timing for switching between the second fuel amount and the third fuel amount, It is also achieved by an engine fuel control device characterized by switching every predetermined number of injections.
The above purpose is
Engine intake air amount measuring means;
Engine speed detection means;
Means for obtaining a predetermined crank angle of the engine;
Means for obtaining a basic fuel amount to be supplied to the engine from the intake air amount measured by the intake air amount measuring means of the engine and the rotational speed detected by the engine speed detecting means;
Means for detecting the oxygen concentration of the exhaust gas discharged from the engine;
Based on the detected oxygen concentration, means for obtaining the first fuel amount by correcting the basic fuel amount so as to obtain a target air-fuel ratio;
Means for obtaining a second fuel amount that is richer than the stoichiometric air-fuel ratio based on the first fuel amount;
Means for obtaining a third fuel amount leaner than the stoichiometric air-fuel ratio based on the first fuel amount;
Means having a region for supplying the first fuel amount according to the state of the engine, and a region for switching and supplying the fuel of the second fuel amount and the third fuel amount according to the injection timing;
Means for injecting into the engine the amount of fuel supplied according to the region and timing at the obtained predetermined crank angle, and the timing for switching between the second fuel amount and the third fuel amount, It is also achieved by an engine fuel control device characterized by switching in accordance with a predetermined pattern.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0008]
FIG. 1 shows the overall configuration of the engine of the present embodiment and the control device for the engine. The engine 100 includes a heating element resistance type air flow meter (hereinafter referred to as an H / W sensor) 101 that measures the amount of air sucked into the engine 100 by resistance of a heating element, and a throttle throttle that adjusts the air flow amount sucked into the engine 100. A valve 103, a throttle opening sensor 102 for converting the opening of the throttle throttle valve 103 into an electrical signal, and a fuel injection valve 104 for supplying fuel to the engine 100 with the given electrical signal; The engine 100 is provided with an ignition plug 105 for igniting a mixture of fuel and air in the cylinder with a given electrical signal and timing, and is installed on the circumference of the crankshaft of the engine to reduce the number of revolutions per unit time. A crank angle sensor 106 for measurement is installed. The exhaust pipe of the engine 100 detects an oxygen concentration in the exhaust gas and generates an electric signal for feedback control for setting the engine 100 as a target air-fuel ratio fuel injection amount, and the oxygen concentration sensor 107 An oxidation-reduction catalyst 108 that oxidizes, reduces, and purifies exhaust gas is installed downstream of the concentration sensor 107, and further, the engine 100 is electrically connected to the H / W sensor 101, the crank angle sensor 106, and the oxygen concentration sensor 107. An engine control device 109 is arranged to process the engine signal based on a predetermined procedure, determine the fuel amount and ignition timing required by the engine 100, and send an electrical signal to the actuator such as the fuel injection valve. Yes.
[0009]
FIG. 2 shows an example of the engine control apparatus of the present embodiment. The engine control device 109 receives signals from sensors installed in each part of the engine 100, converts a small signal (TTL level) into a large signal for driving an actuator, and digitally processes input / output signals. Input / output circuit 202 that performs analog-to-digital signal conversion, a microcomputer that performs digital arithmetic processing, or an arithmetic circuit 203 that has an arithmetic circuit equivalent thereto, a non-volatile that stores constants and programs used for arithmetic processing of arithmetic circuit 203 Volatile memory 204, volatile memory 205 for storing variables, memory of arithmetic circuit 203, and power supply holding circuit (backup) 206 for holding the contents of volatile memory 205. In this embodiment, the input / output circuit 202 and the arithmetic circuit 203 are described separately, but the arithmetic circuit 203 may include the input / output circuit 202. Further, the engine control apparatus of the present embodiment receives electrical signals from the H / W sensor, oxygen concentration sensor, crank angle sensor, throttle opening sensor, and water temperature sensor, and outputs drive signals for the fuel injection valve and spark plug. Output.
[0010]
FIG. 3 shows the relationship between the air-fuel ratio (the mixture ratio of gasoline and air) of the engine according to the present embodiment, the unburned gasoline (HC) 301 to be discharged, the nitrogen oxide (NOx) 302, and the fuel consumption rate 303. . When the air-fuel ratio is richer than the stoichiometric air-fuel ratio, a large amount of HC is discharged, and when the air-fuel ratio becomes leaner than the stoichiometric air-fuel ratio, the discharge amount decreases rapidly. On the other hand, NOx gradually increases as it becomes leaner than the stoichiometric air-fuel ratio. Further, it is indicated that the place where the fuel consumption rate becomes the minimum is slightly on the lean side from the stoichiometric air-fuel ratio.
[0011]
FIG. 4 shows an example of the fuel injection mode of the configuration of the present invention. A solid line 401 indicates the fuel injection width that is actually injected. A broken line 402 indicates the fuel injection width necessary for maintaining the stoichiometric air-fuel ratio. Therefore, fuel richer than the stoichiometric air-fuel ratio is injected into the fuel injection width 403, and the fuel injection width leaner than the stoichiometric air-fuel ratio is set as the other fuel injection width. A chart 404 is a cylinder counter that is incremented at each fuel injection timing and reset when a predetermined value 405 is reached. The fuel injection amount of the fuel injection width 403 is set at the reset timing.
[0012]
FIG. 5 is another example of the fuel injection mode of the configuration of the present invention. With respect to the configuration of FIG. 4 described above, the timing at which the fuel injection width on the richer side than the stoichiometric air-fuel ratio is set follows the fuel injection pattern table for each fuel injection timing. FIG. 6 shows a region in which the fuel injection mode of the configuration shown in FIGS. 4 and 5 is executed. A region 601 is a region in which air-fuel ratio feedback is performed based on the output of the oxygen concentration sensor installed in the exhaust pipe. A region 602 is a region (intermittent lean region) in which the fuel injection mode of the configuration shown in FIGS. 4 and 5 is executed. A region 603 is a power region, in which fuel injection richer than the stoichiometric air-fuel ratio is performed.
[0013]
FIG. 7 shows the relationship between the oxygen concentration sensor output and the feedback coefficient, and the air-fuel ratio correction coefficient when the fuel injection mode shown in FIGS. 4 and 5 is performed. A chart 701 is an output of the above-described oxygen concentration sensor, and a chart 702 is an air-fuel ratio correction coefficient calculated from the oxygen concentration sensor output. A coefficient 703 is an average value of the air-fuel ratio correction coefficient calculated by a weighted average or a moving average. The coefficient 704 is a coefficient for calculating the rich side fuel injection width in FIGS. 4 and 5 calculated from the above-mentioned average value of the air-fuel ratio correction coefficient, and the coefficient 705 is a coefficient for calculating the lean side fuel injection width.
[0014]
FIG. 8 shows a flowchart of fuel injection of the engine control apparatus of the configuration of the present invention. In step 801, the output of the H / W sensor is read. In step 802, the engine speed calculated from the signal of the crank angle sensor of the engine is read. In steps 803 and 804, the engine load and the basic fuel amount are calculated based on the above-mentioned H / W sensor output and engine speed. In step 805, the fuel injection mode determined by the engine speed and the engine load is determined. If it is the air-fuel ratio feedback region, the process branches to step 806, if it is the intermittent lean control region, step 807, and if it is the power region, the process branches to step 808 and the respective air-fuel ratio correction is performed. Each corrected fuel is set in step 809 and actually injected into the engine.
[0015]
FIG. 9 shows a flowchart of the aforementioned air-fuel ratio feedback. In step 901, the output of the oxygen concentration sensor is read. In step 902, it is determined whether or not the aforementioned oxygen concentration sensor output is greater than a predetermined value. Steps 903, 904, and 905 are processes when the output of the oxygen concentration sensor is larger than a predetermined value, and as shown in the flow, feedback correction for differential and integral is performed on the air-fuel ratio correction coefficient αf. . Steps 906, 907, and 908 are feedback correction when the above-mentioned oxygen concentration sensor output is smaller than a predetermined value.
[0016]
FIG. 10 is a flowchart for calculating the coefficient of air-fuel ratio correction used in the above-described intermittent lean region. In step 1001, the air-fuel ratio correction coefficient α is read. In step 1002, the average value αf of the aforementioned air-fuel ratio correction coefficient αf is calculated. In steps 1003 and 1004, the engine speed and the basic fuel amount are read. In steps 1005 and 1006, the lean side fuel gain Kl and the rich side fuel gain Kr are retrieved from the map of engine speed and basic fuel amount. In steps 1007 and 1008, the lean side fuel correction coefficient αl and the rich side fuel correction coefficient αr are calculated from the aforementioned lean, rich side fuel gain, and air-fuel ratio correction coefficient average value αf.
[0017]
FIG. 11 is an example of the above-described intermittent lean fuel correction flowchart. This flowchart is executed for engine crank angle synchronization, particularly for each fuel injection amount set. In step 1101, the cylinder counter is incremented. In step 1102, it is determined whether the cylinder counter is equal to or greater than a predetermined value. If the cylinder counter is greater than or equal to a predetermined value, the rich side air-fuel ratio correction coefficient αr is read in step 1103, and if it is less than the predetermined value, the lean side air-fuel ratio correction coefficient αl is read in step 1104 and the cylinder counter is cleared (reset) in step 1105. To do. In step 1106, the basic fuel amount is corrected with the read air-fuel ratio correction coefficient, and intermittent lean control is performed.
[0018]
FIG. 12 is another example of the above-described intermittent lean fuel correction flowchart. For the example of FIG. 11 described above, switching between the rich fuel side correction coefficient and the lean side fuel correction coefficient is determined by reading the intermittent fuel injection pattern table in step 1201.
[0019]
Although one embodiment of the present invention has been described above, the engine fuel control device according to the present invention configured as described above reduces fuel consumption by injecting fuel on the lean side with respect to the theoretical air-fuel ratio. . The nitrogen oxides generated at this time are temporarily stored in a redox catalyst installed downstream of the exhaust pipe, and are then reduced by fuel that is richer than the stoichiometric air-fuel ratio that is injected thereafter. To reduce emissions.
[0020]
【The invention's effect】
According to the present embodiment, it is possible to reduce fuel consumption without increasing harmful exhaust components (particularly nitrogen oxides) during vehicle travel. Further, since the control region of the feature of the present invention is divided according to the state of the engine, drivability is not impaired.
[Brief description of the drawings]
FIG. 1 is an example of a configuration diagram of an engine and an engine control apparatus according to an embodiment of the present invention.
FIG. 2 is an example of a conceptual diagram of a configuration of an engine control device according to the present invention.
FIG. 3 is an example of a correlation diagram of an air-fuel ratio, an exhaust gas component, and a fuel consumption rate of the engine of the present invention.
FIG. 4 shows an example of a fuel injection mode of the present invention.
FIG. 5 shows another example of the fuel injection mode of the present invention.
FIG. 6 shows an example of a region where the fuel injection mode of the present invention is executed.
FIG. 7 is a correlation diagram of the output of the oxygen concentration sensor, the feedback coefficient, and the air-fuel ratio correction coefficient of the present invention. FIG. 8 is an example of a fuel injection flowchart of the control apparatus of the present invention.
FIG. 9 shows an example of an air-fuel ratio feedback flowchart of the control device of the present invention.
FIG. 10 is an example of a flowchart for calculating an air-fuel ratio correction coefficient in the intermittent lean region of the control device of the present invention.
FIG. 11 is an example of a flowchart of intermittent lean fuel correction of the control device of the present invention.
FIG. 12 is another example of a flowchart of intermittent lean fuel correction of the control device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 ... Engine, 101 ... Heating body resistance type air flowmeter, 104 ... Fuel injection valve, 106 ... Crank angle sensor, 107 ... Oxygen concentration sensor, 109 ... Engine control apparatus.

Claims

Engine intake air amount measuring means;
Engine speed detection means;
Means for obtaining a predetermined crank angle of the engine;
Means for obtaining a basic fuel amount to be supplied to the engine from the intake air amount measured by the intake air amount measuring means of the engine and the rotational speed detected by the engine speed detecting means;
Means for detecting the oxygen concentration of the exhaust gas discharged from the engine;
Based on the detected oxygen concentration, means for obtaining the first fuel amount by correcting the basic fuel amount so as to obtain a target air-fuel ratio;
Means for obtaining a second fuel amount that is richer than the stoichiometric air-fuel ratio based on the first fuel amount;
Means for obtaining a third fuel amount leaner than the stoichiometric air-fuel ratio based on the first fuel amount;
Means having a region for supplying the first fuel amount according to the state of the engine, and a region for switching and supplying the fuel of the second fuel amount and the third fuel amount according to the injection timing;
Means for injecting into the engine the amount of fuel supplied in accordance with the region and timing at the predetermined crank angle obtained, and switching between the second fuel amount and the third fuel amount to supply An engine fuel control device characterized in that, in the region, the average air-fuel ratio in the region is leaner than the stoichiometric air-fuel ratio .

Engine intake air amount measuring means;
Engine speed detection means;
Means for obtaining a predetermined crank angle of the engine;
Means for obtaining a basic fuel amount to be supplied to the engine from the intake air amount measured by the intake air amount measuring means of the engine and the rotational speed detected by the engine speed detecting means;
Means for detecting the oxygen concentration of the exhaust gas discharged from the engine;
Based on the detected oxygen concentration, means for obtaining the first fuel amount by correcting the basic fuel amount so as to obtain a target air-fuel ratio;
Means for obtaining a second fuel amount that is richer than the stoichiometric air-fuel ratio based on the first fuel amount;
Means for obtaining a third fuel amount leaner than the stoichiometric air-fuel ratio based on the first fuel amount;
Means having a region for supplying the first fuel amount according to the state of the engine, and a region for switching and supplying the fuel of the second fuel amount and the third fuel amount according to the injection timing;
Means for injecting into the engine the amount of fuel supplied according to the region and timing at the obtained predetermined crank angle, and the timing for switching between the second fuel amount and the third fuel amount, A fuel control apparatus for an engine, which is switched at every predetermined number of injections.

Engine intake air amount measuring means;
Engine speed detection means;
Means for obtaining a predetermined crank angle of the engine;
Means for obtaining a basic fuel amount to be supplied to the engine from the intake air amount measured by the intake air amount measuring means of the engine and the rotational speed detected by the engine speed detecting means;
Means for detecting the oxygen concentration of the exhaust gas discharged from the engine;
Based on the detected oxygen concentration, means for obtaining the first fuel amount by correcting the basic fuel amount so as to obtain a target air-fuel ratio;
Means for obtaining a second fuel amount that is richer than the stoichiometric air-fuel ratio based on the first fuel amount;
Means for obtaining a third fuel amount leaner than the stoichiometric air-fuel ratio based on the first fuel amount;
Means having a region for supplying the first fuel amount according to the state of the engine, and a region for switching and supplying the fuel of the second fuel amount and the third fuel amount according to the injection timing;
Means for injecting into the engine the amount of fuel supplied according to the region and timing at the obtained predetermined crank angle, and the timing for switching between the second fuel amount and the third fuel amount, A fuel control apparatus for an engine characterized by switching according to a predetermined pattern.