JP3838526B2 - Fuel injection control device and fuel injection control method for internal combustion engine - Google Patents

Fuel injection control device and fuel injection control method for internal combustion engine Download PDF

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JP3838526B2
JP3838526B2 JP09183397A JP9183397A JP3838526B2 JP 3838526 B2 JP3838526 B2 JP 3838526B2 JP 09183397 A JP09183397 A JP 09183397A JP 9183397 A JP9183397 A JP 9183397A JP 3838526 B2 JP3838526 B2 JP 3838526B2
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pressure
injection amount
atmospheric pressure
correction coefficient
fuel injection
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JPH10280988A (en
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辰則 加藤
豊 新田
明久 田村
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Denso Corp
Suzuki Motor Co Ltd
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Suzuki Motor Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
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Description

【０００１】
【発明の属する技術分野】
本発明は、吸気圧と大気圧との差圧と内燃機関回転数とに基づいて燃料噴射量を算出する内燃機関の燃料噴射制御装置及び燃料噴射制御方法に関するものである。
【０００２】
【従来の技術】
一般に、車両に搭載された内燃機関では、吸気圧が同じでも、走行する道路の標高が高くなって大気圧が低下すると、吸入空気量が変化するため、燃料噴射量を補正することが好ましい。そのために、例えば、特開平５−１４９１８７号公報では、内燃機関の吸気圧を吸気圧センサで検出し、この検出吸気圧を基準大気圧（７６０ｍｍＨｇ）下で同等の吸入空気量となる吸気圧に補正するための大気圧補正係数によって補正して、補正吸気圧を求め、この補正吸気圧に基づいて燃料噴射量を算出するようにしている。
【０００３】
ところで、大気圧の変化による燃料噴射量のずれ（空燃比のずれ）を少なくするには、吸気圧と大気圧との差圧（以下「相対圧」という）を用いて燃料噴射量を算出することが効果的であるが、上記公報の技術では、吸気圧（絶対圧）を用いて燃料噴射量を算出するため、大気圧の変化による影響を受けやすく、たとえ吸気圧を大気圧補正係数で補正しても、その補正誤差により燃料噴射量の算出精度が低下するという欠点がある。
【０００４】
そこで、特開昭６０−２４７０２１号公報に示すように、相対圧を検出し、この相対圧に基づいて燃料噴射量を算出した後、この燃料噴射量を大気圧補正係数により補正するようにしたものがある。
【０００５】
【発明が解決しようとする課題】
上記公報の技術は、相対圧から算出した燃料噴射量のずれを大気圧補正係数で補正することを狙ったものであるが、相対圧と燃料噴射量と大気圧（大気圧補正係数）との関係は一義的に決まらないため、相対圧から算出した燃料噴射量のずれを大気圧補正係数で精度良く補正することは不可能であり、空燃比のずれが生じて、排気エミッション増加やドライバビリティ低下を招くという欠点がある。
【０００６】
本発明はこのような事情を考慮してなされたものであり、従ってその目的は、大気圧が変化しても、燃料噴射量を精度良く算出することができ、排気エミッション低減やドライバビリティ向上を実現することができる内燃機関の燃料噴射制御装置及び燃料噴射制御方法を提供することにある。
【０００７】
【課題を解決するための手段】
上記目的を達成するために、本発明の請求項１，３によれば、相対圧補正手段により吸気圧と大気圧との差圧（相対圧）を大気圧に応じた相対圧補正係数により基準大気圧状態での相対圧に補正し、補正後の相対圧と内燃機関回転数とに基づいて基本噴射量を基本噴射量算出手段により算出した後、この基本噴射量を最終噴射量算出手段により大気圧に応じた噴射量補正係数で補正して燃料噴射量を求める。
【０００８】
このようにすれば、相対圧から基本噴射量を算出する過程、及び、基本噴射量から燃料噴射量を算出する過程で、いずれも大気圧に応じた補正を行うことができる。これにより、大気圧が変化しても、燃料噴射量を精度良く算出することができ、排気エミッション低減やドライバビリティ向上を実現することができる。
【０００９】
この場合、請求項１のように、前記相対圧補正係数として、基準大気圧を検出大気圧で割り算した値を用いるようにしても良い。このようにすれば、相対圧補正係数のマップデータを記憶手段に記憶しておく必要がなく、その分、記憶手段のメモリ容量が少なくて済む（又はメモリを節約できる）。
【００１０】
但し、本発明は、相対圧補正係数のマップデータを記憶手段に記憶し、このマップデータから検出大気圧に応じて相対圧補正係数を設定するようにしても良いことは言うまでもない。
【００１１】
この場合、請求項２のように、相対圧補正係数のマップデータと噴射量補正係数のマップデータは、常用域である基準大気圧付近で細かくデータを設定すると良い。このようにすれば、常用域で大気圧の変化に応じて相対圧補正係数と噴射量補正係数を精度良く求めることができ、常用域での燃料噴射量の算出精度を向上することができる。
また、請求項４のように、記憶手段に記憶された相対圧補正係数のマップデータを使用する場合は、この相対圧補正係数のマップデータから大気圧に応じた相対圧補正係数を設定するようにすれば良い。
【００１２】
【発明の実施の形態】
以下、本発明を二輪車に適用した一実施形態を図面に基づいて説明する。内燃機関であるエンジン１１の各気筒の吸気ポート１０には、それぞれ吸気マニホールド１２が接続され、各気筒の吸気マニホールド１２の上流側にはエアボックス１３が接続され、このエアボックス１３内に吸入された空気が各気筒の吸気マニホールド１２に吸い込まれる。このエアボックス１３内にはエアクリーナ３３が装着され、また、このエアボックス１３には、吸気温を検出する吸気温センサ１４が取り付けられている。各気筒の吸気マニホールド１２の途中には、スロットルバルブ１５が取り付けられ、このスロットルバルブ１５の開度（スロットル開度）がスロットル開度センサ１６によって検出される。更に、吸気マニホールド１２のうちのスロットルバルブ１５の下流側には、吸気圧を検出する吸気圧センサ１７（吸気圧検出手段）が設けられ、各気筒の吸気ポート１０の近傍には燃料噴射弁１８が取り付けられている。
【００１３】
一方、燃料タンク１９内から燃料ポンプ２０で汲み上げられた燃料は、燃料配管２１→燃料フィルタ２２→燃料配管２３→デリバリパイプ２４に送られ、各気筒の燃料噴射弁１８に分配される。デリバリパイプ２４内の余剰燃料は、プレッシャレギュレータ２５→リターン配管２６の経路で燃料タンク１９内に戻される。プレッシャレギュレータ２５は、デリバリパイプ２４内の燃料圧力と吸気圧との差圧が一定になるようにデリバリパイプ２４内の燃料圧力を調整する。
【００１４】
エンジン１１のシリンダヘッドには、気筒毎に点火プラグ２７が取り付けられ、点火タイミング毎に点火コイル２８の二次側に発生する高電圧が各気筒の点火プラグ２７に印加され、点火される。このエンジン１１には、エンジン回転数を検出するために所定クランク角毎にパルス信号（クランク角信号）を出力するエンジン回転数センサ２９（回転数検出手段）と、特定気筒を判別する気筒判別センサ３０と、冷却水温を検出する水温センサ３１とが取り付けられている。また、車体の所定位置には、大気圧を検出する大気圧センサ３２（大気圧検出手段）が取り付けられている。
【００１５】
これら大気圧センサ３２の出力信号や前述した吸気圧センサ１７等の各種センサの出力信号は、エンジン制御回路３５に入力される。このエンジン制御回路３５は、マイクロコンピュータを主体として構成され、内蔵したＲＯＭ４５（記憶手段）には、点火制御用のルーチンや、図２の燃料噴射制御ルーチンや、図３及び図４のマップデータ等が記憶されている。
【００１６】
このエンジン制御回路３５は、図２の燃料噴射制御ルーチンを実行することで、吸気圧のボトム圧Ｐb と大気圧Ｐa との差圧（相対圧）を、大気圧Ｐa に応じた相対圧補正係数ＫPaで補正し、補正後の相対圧Ｐdlとエンジン回転数ＮＥとに基づいて基本噴射時間ＴＰ（基本噴射量に相当）を算出した後、この基本噴射時間ＴＰを大気圧Ｐa に応じた噴射量補正係数ＫPad で補正して最終燃料噴射時間ＴＡＵ（燃料噴射量に相当）を求める。
【００１７】
以下、この図２の燃料噴射制御ルーチンの処理内容を説明する。本ルーチンは各気筒の燃料噴射タイミングの直前に実行される。本ルーチンが起動されると、まずステップ１０１で、吸気圧センサ１７で検出した吸気圧のボトム圧Ｐb を読み込む。ここで、ボトム圧Ｐb は、図５に示すように、吸気行程により低下する吸気圧の最下点であり、吸気行程から圧縮行程に移行する時の吸気圧がボトム圧Ｐb として読み込まれる。このボトム圧Ｐb は、１サイクル毎に更新される。
【００１８】
この後、ステップ１０２で、大気圧センサ３２で検出した大気圧Ｐa を読み込み、次のステップ１０３で、エンジン回転数センサ２９の出力信号から検出されたエンジン回転数ＮＥを読み込む。この後、ステップ１０４に進み、吸気圧のボトム圧Ｐb と大気圧Ｐa との差圧、つまり相対圧（Ｐa −Ｐb ）を算出した後、ステップ１０５で、大気圧Ｐa に応じた相対圧補正係数ＫPaを算出する。この相対圧補正係数ＫPaの算出方法は、次の（１）又は（２）のいずれかの方法を用いる。
【００１９】
（１）基準大気圧（７６０ｍｍＨｇ）を検出大気圧Ｐa で割り算した値を相対圧補正係数ＫPaとする（相対圧補正係数ＫPa＝基準大気圧÷検出大気圧Ｐa ）。
（２）予め、試験又はシミュレーション等により大気圧Ｐa と相対圧補正係数ＫPaとの関係を求め、その関係をマップデータ（図３参照）としてエンジン制御回路３５のＲＯＭ４５に記憶しておき、検出大気圧Ｐa に応じた相対圧補正係数ＫPaをマップデータを検索して求める。この相対圧補正係数ＫPaのマップデータは、常用域である基準大気圧付近で細かくデータが設定されている。
【００２０】
上記（１）又は（２）のいずれかの方法で相対圧補正係数ＫPaを算出した後、ステップ１０６で、相対圧（Ｐa −Ｐb ）を基準大気圧（７６０ｍｍＨｇ）の状態に補正するために、相対圧（Ｐa −Ｐb ）に相対圧補正係数ＫPaを乗算して、相対圧補正値Ｐdlを算出する［Ｐdl＝（Ｐa −Ｐb ）×ＫPa］。このステップ１０６の処理が特許請求の範囲でいう相対圧補正手段としての役割を果たす。
【００２１】
この後、ステップ１０７で、相対圧補正値Ｐdlとエンジン回転数ＮＥとに基づいて基本噴射時間ＴＰを算出する。この算出方法は、予め実験又はシミュレーション等によって相対圧補正値Ｐdlとエンジン回転数ＮＥと基本噴射時間ＴＰとの関係を求めて、基本噴射時間ＴＰの二次元マップを作成し、このマップをエンジン制御回路３５のＲＯＭ４５に記憶しておき、ステップ１０７で、このマップを検索して、その時の相対圧補正値Ｐdlとエンジン回転数ＮＥとに応じた基本噴射時間ＴＰを算出する。このステップ１０７の処理が特許請求の範囲でいう基本噴射量算出手段としての役割を果たす。
【００２２】
基本噴射時間ＴＰの算出後、ステップ１０８で、大気圧Ｐa に応じた噴射量補正係数ＫPad を算出する。この算出方法は、予め実験又はシミュレーション等によって大気圧Ｐa と噴射量補正係数ＫPad との関係を求め、その関係をマップデータ（図４参照）としてエンジン制御回路３５のＲＯＭ４５に記憶しておき、検出大気圧Ｐa に応じた噴射量補正係数ＫPad をマップデータを検索して求める。この噴射量補正係数ＫPad のマップデータは、常用域である基準大気圧付近で細かくデータが設定されている。
【００２３】
そして、次のステップ１０９で、噴射量補正係数ＫPad 以外の各種の補正係数Ｋを算出する。例えば、水温センサ３１の出力信号（冷却水温）に応じた暖機増量補正係数、始動後増量補正係数、吸気温センサ１４の出力信号（吸気温）に応じた吸気温補正係数等、各種の補正係数Ｋを算出する。
【００２４】
この後、ステップ１１０で、電源電圧に基づいて燃料噴射弁１８の応答遅れ時間、つまり無効噴射時間ＴＶを算出し、次のステップ１１１で、燃料噴射弁１８に出力する噴射パルスのパルス幅である最終噴射時間ＴＡＵを、基本噴射時間ＴＰと噴射量補正係数ＫPad と各種補正係数Ｋと無効噴射時間ＴＶを用いて次式により算出する。
ＴＡＵ＝ＴＰ×ＫPad ×Ｋ＋ＴＶ
ここで、補正係数Ｋには、暖機増量補正係数、始動後増量補正係数、吸気温補正係数等、各種の補正係数が含まれる。このステップ１１１の処理が特許請求の範囲でいう最終噴射量算出手段としての役割を果たす。
【００２５】
以上説明した本実施形態によれば、相対圧（Ｐa −Ｐb ）から基本噴射時間ＴＰを算出する過程、及び、基本噴射時間ＴＰから最終噴射時間ＴＡＵを算出する過程で、いずれも大気圧Ｐa に応じた補正係数ＫPa，ＫPad を用いて基本噴射時間ＴＰと最終噴射時間ＴＡＵの双方を補正するため、従来のように基本噴射時間ＴＰと最終噴射時間ＴＡＵのいずれか一方のみを大気圧Ｐa に応じて補正する場合と比較して、最終噴射時間ＴＡＵを精度良く算出することができ、排気エミッション低減やドライバビリティ向上を実現することができる。
【００２６】
更に、本実施形態によれば、相対圧補正係数ＫPaのマップデータと噴射量補正係数ＫPad のマップデータは、常用域である基準大気圧付近で細かくデータを設定しているので、常用域で大気圧Ｐa の変化に応じて相対圧補正係数ＫPaと噴射量補正係数ＫPad を精度良く求めることができ、常用域での最終噴射時間ＴＡＵの算出精度を向上することができる。
【００２７】
しかしながら、本発明は、相対圧補正係数ＫPaのマップデータと噴射量補正係数ＫPad のマップデータは、必ずしも基準大気圧付近（常用域）で細かくデータを設定する必要はなく、常用域のデータの設定間隔をそれ以外の領域の設定間隔と同じにしても良く、この場合でも、本発明の所期の目的を十分に達成できる。
【００２８】
尚、本実施形態では、相対圧補正係数ＫPaと噴射量補正係数ＫPad は、いずれも大気圧Ｐa をパラメータとする一次元マップから求めるようにしたが、大気圧Ｐa とエンジン回転数ＮＥをパラメータとする二次元マップから求めるようにしても良い。
【００２９】
また、本実施形態では、相対圧を吸気圧のボトム圧Ｐb と大気圧Ｐa との差圧としたが、吸気圧の平均値（平均吸気圧）と大気圧Ｐa との差圧としても良い。
相対圧＝大気圧Ｐa −平均吸気圧
【００３０】
また、本実施形態では、全運転領域で相対圧補正値Ｐdlとエンジン回転数ＮＥとに基づいて基本噴射時間ＴＰを算出するようにしたが、例えば低負荷領域のみで、相対圧補正値Ｐdlとエンジン回転数ＮＥとに基づいて基本噴射時間ＴＰを算出し、中負荷・高負荷領域では、スロットル開度とエンジン回転数ＮＥとに基づいて基本噴射時間ＴＰを算出するようにしても良い。
【００３１】
また、本実施形態では、大気圧Ｐa を大気圧センサ３２により検出したが、エンジン始動直後の吸気圧センサ１７の出力値又はエンジン停止から所定時間経過後の吸気圧センサ１７の出力値を大気圧Ｐa としてエンジン制御回路３５内に取り込んでバックアップＲＡＭ（図示せず）に記憶しておき、この記憶値を大気圧Ｐa として用いるようにしても良い。この場合には、大気圧センサ３２が不要となる。
その他、本発明は、二輪車に限定されず、四輪車にも適用して実施できる。
【図面の簡単な説明】
【図１】本発明の一実施形態を示すエンジン制御システム全体の概略構成図
【図２】燃料噴射制御ルーチンの処理の流れを示すフローチャート
【図３】相対圧補正係数ＫPaのマップを概念的に示す図
【図４】噴射量補正係数ＫPad のマップを概念的に示す図
【図５】吸気圧の挙動を示すタイムチャート
【符号の説明】
１１…エンジン（内燃機関）、１２…吸気マニホールド、１３…エアボックス、１５…スロットルバルブ、１６…スロットル開度センサ、１７…吸気圧センサ（吸気圧検出手段）、１８…燃料噴射弁、２９…エンジン回転数センサ（回転数検出手段）、３２…大気圧センサ（大気圧検出手段）、３５…エンジン制御回路（基本噴射量算出手段，最終噴射量算出手段）、４５…ＲＯＭ（記憶手段）。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection control device and a fuel injection control method for an internal combustion engine that calculate a fuel injection amount based on a differential pressure between intake pressure and atmospheric pressure and the internal combustion engine speed.
[0002]
[Prior art]
In general, in an internal combustion engine mounted on a vehicle, it is preferable to correct the fuel injection amount because the intake air amount changes when the altitude of the road on which the vehicle runs increases and the atmospheric pressure decreases even if the intake pressure is the same. For this purpose, for example, in Japanese Patent Application Laid-Open No. 5-149187, the intake pressure of the internal combustion engine is detected by an intake pressure sensor, and this detected intake pressure is set to an intake pressure that provides an equivalent intake air amount under a reference atmospheric pressure (760 mmHg). Correction is made by an atmospheric pressure correction coefficient for correction to obtain a corrected intake pressure, and a fuel injection amount is calculated based on the corrected intake pressure.
[0003]
By the way, in order to reduce the difference in fuel injection amount (air-fuel ratio difference) due to changes in atmospheric pressure, the fuel injection amount is calculated using the differential pressure between the intake pressure and atmospheric pressure (hereinafter referred to as “relative pressure”). However, in the technique of the above publication, since the fuel injection amount is calculated using the intake pressure (absolute pressure), it is easily affected by changes in the atmospheric pressure. Even if it correct | amends, there exists a fault that the calculation precision of fuel injection quantity falls by the correction error.
[0004]
Therefore, as disclosed in Japanese Patent Laid-Open No. 60-247021, after detecting the relative pressure and calculating the fuel injection amount based on the relative pressure, the fuel injection amount is corrected by the atmospheric pressure correction coefficient. There is something.
[0005]
[Problems to be solved by the invention]
The technique of the above publication aims to correct the deviation of the fuel injection amount calculated from the relative pressure with the atmospheric pressure correction coefficient, but the relative pressure, the fuel injection amount, and the atmospheric pressure (atmospheric pressure correction coefficient) Since the relationship is not uniquely determined, it is impossible to accurately correct the deviation in the fuel injection amount calculated from the relative pressure using the atmospheric pressure correction coefficient, resulting in a deviation in the air-fuel ratio resulting in increased exhaust emissions and drivability. There is a disadvantage of causing a decrease.
[0006]
The present invention has been made in view of such circumstances. Therefore, even if the atmospheric pressure changes, the object of the present invention is to accurately calculate the fuel injection amount, and to reduce exhaust emissions and improve drivability. An object of the present invention is to provide a fuel injection control device and a fuel injection control method for an internal combustion engine that can be realized.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the first and third aspects of the present invention, the relative pressure correction means uses the relative pressure correction coefficient corresponding to the atmospheric pressure as a reference for the differential pressure (relative pressure) between the intake pressure and the atmospheric pressure. After correcting to the relative pressure in the atmospheric pressure state and calculating the basic injection amount by the basic injection amount calculating means based on the corrected relative pressure and the internal combustion engine speed, the basic injection amount is calculated by the final injection amount calculating means. The fuel injection amount is obtained by correcting with an injection amount correction coefficient corresponding to the atmospheric pressure.
[0008]
If this good earthenware pots, the process calculates a basic injection amount from the relative pressure and, in the process of calculating the amount of fuel injection from the basic injection amount, it is possible to perform any correction according to the atmospheric pressure. Thereby, even if the atmospheric pressure changes, the fuel injection amount can be calculated with high accuracy, and exhaust emission reduction and drivability improvement can be realized.
[0009]
In this case, as in claim 1, as the relative pressure correction coefficient, the reference atmospheric pressure may be used a value obtained by dividing the detection atmospheric pressure. In this way, it is not necessary to store the map data of the relative pressure correction coefficient in the storage means, and accordingly the memory capacity of the storage means can be reduced (or the memory can be saved).
[0010]
However, it goes without saying that the present invention may store map data of the relative pressure correction coefficient in the storage means and set the relative pressure correction coefficient from this map data according to the detected atmospheric pressure.
[0011]
In this case, as described in claim 2 , the map data of the relative pressure correction coefficient and the map data of the injection amount correction coefficient may be set finely in the vicinity of the reference atmospheric pressure, which is the normal range. In this way, the relative pressure correction coefficient and the injection amount correction coefficient can be accurately obtained in accordance with the change in atmospheric pressure in the normal range, and the calculation accuracy of the fuel injection amount in the normal range can be improved.
Further, when using the map data of the relative pressure correction coefficient stored in the storage means as in claim 4 , the relative pressure correction coefficient corresponding to the atmospheric pressure is set from the map data of the relative pressure correction coefficient. You can do it.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a motorcycle will be described with reference to the drawings. An intake manifold 12 is connected to the intake port 10 of each cylinder of the engine 11 which is an internal combustion engine, and an air box 13 is connected to the upstream side of the intake manifold 12 of each cylinder, and is sucked into the air box 13. Air is sucked into the intake manifold 12 of each cylinder. An air cleaner 33 is mounted in the air box 13, and an intake air temperature sensor 14 for detecting the intake air temperature is attached to the air box 13. A throttle valve 15 is attached in the middle of the intake manifold 12 of each cylinder, and an opening degree (throttle opening degree) of the throttle valve 15 is detected by a throttle opening degree sensor 16. Further, an intake pressure sensor 17 (intake pressure detecting means) for detecting intake pressure is provided on the downstream side of the throttle valve 15 in the intake manifold 12, and a fuel injection valve 18 is provided in the vicinity of the intake port 10 of each cylinder. Is attached.
[0013]
On the other hand, the fuel pumped up from the fuel tank 19 by the fuel pump 20 is sent to the fuel pipe 21 → the fuel filter 22 → the fuel pipe 23 → the delivery pipe 24, and is distributed to the fuel injection valve 18 of each cylinder. Excess fuel in the delivery pipe 24 is returned to the fuel tank 19 through a path of the pressure regulator 25 → the return pipe 26. The pressure regulator 25 adjusts the fuel pressure in the delivery pipe 24 so that the differential pressure between the fuel pressure in the delivery pipe 24 and the intake pressure is constant.
[0014]
An ignition plug 27 is attached to the cylinder head of the engine 11 for each cylinder, and a high voltage generated on the secondary side of the ignition coil 28 at each ignition timing is applied to the ignition plug 27 of each cylinder and ignited. The engine 11 includes an engine speed sensor 29 (rotation speed detection means) that outputs a pulse signal (crank angle signal) at every predetermined crank angle in order to detect the engine speed, and a cylinder discrimination sensor that discriminates a specific cylinder. 30 and a water temperature sensor 31 for detecting the cooling water temperature are attached. An atmospheric pressure sensor 32 (atmospheric pressure detecting means) for detecting atmospheric pressure is attached to a predetermined position of the vehicle body.
[0015]
The output signals of these atmospheric pressure sensors 32 and the output signals of various sensors such as the intake pressure sensor 17 described above are input to the engine control circuit 35. The engine control circuit 35 is mainly composed of a microcomputer, and a built-in ROM 45 (storage means) has an ignition control routine, a fuel injection control routine in FIG. 2, map data in FIGS. 3 and 4, and the like. Is remembered.
[0016]
The engine control circuit 35 executes the fuel injection control routine of FIG. 2 so that the differential pressure (relative pressure) between the bottom pressure Pb of the intake pressure and the atmospheric pressure Pa is changed to a relative pressure correction coefficient corresponding to the atmospheric pressure Pa. After correcting with KPa and calculating the basic injection time TP (corresponding to the basic injection amount) based on the corrected relative pressure Pdl and the engine speed NE, the basic injection time TP is injected according to the atmospheric pressure Pa. The final fuel injection time TAU (corresponding to the fuel injection amount) is obtained by correcting with the correction coefficient KPad.
[0017]
Hereinafter, the processing content of the fuel injection control routine of FIG. 2 will be described. This routine is executed immediately before the fuel injection timing of each cylinder. When this routine is started, first, at step 101, the bottom pressure Pb of the intake pressure detected by the intake pressure sensor 17 is read. Here, as shown in FIG. 5, the bottom pressure Pb is the lowest point of the intake pressure that decreases due to the intake stroke, and the intake pressure at the time of transition from the intake stroke to the compression stroke is read as the bottom pressure Pb. This bottom pressure Pb is updated every cycle.
[0018]
Thereafter, in step 102, the atmospheric pressure Pa detected by the atmospheric pressure sensor 32 is read, and in the next step 103, the engine speed NE detected from the output signal of the engine speed sensor 29 is read. Thereafter, the process proceeds to step 104, and after calculating the differential pressure between the bottom pressure Pb of the intake pressure and the atmospheric pressure Pa, that is, the relative pressure (Pa-Pb), the relative pressure correction coefficient corresponding to the atmospheric pressure Pa is calculated in step 105. KPa is calculated. As a method for calculating the relative pressure correction coefficient KPa, one of the following methods (1) and (2) is used.
[0019]
(1) A value obtained by dividing the reference atmospheric pressure (760 mmHg) by the detected atmospheric pressure Pa is defined as a relative pressure correction coefficient KPa (relative pressure correction coefficient KPa = reference atmospheric pressure ÷ detected atmospheric pressure Pa).
(2) The relationship between the atmospheric pressure Pa and the relative pressure correction coefficient KPa is obtained in advance by a test or simulation, and the relationship is stored in the ROM 45 of the engine control circuit 35 as map data (see FIG. 3). A relative pressure correction coefficient KPa corresponding to the atmospheric pressure Pa is obtained by searching map data. The map data of the relative pressure correction coefficient KPa is finely set in the vicinity of the reference atmospheric pressure that is the normal range.
[0020]
After calculating the relative pressure correction coefficient KPa by either of the above methods (1) or (2), in step 106, in order to correct the relative pressure (Pa-Pb) to the reference atmospheric pressure (760 mmHg) state, The relative pressure correction value Pdl is calculated by multiplying the relative pressure (Pa−Pb) by the relative pressure correction coefficient KPa [Pdl = (Pa−Pb) × KPa]. The processing of step 106 serves as a relative pressure correction means in the claims.
[0021]
Thereafter, in step 107, the basic injection time TP is calculated based on the relative pressure correction value Pdl and the engine speed NE. In this calculation method, a relationship between the relative pressure correction value Pdl, the engine speed NE, and the basic injection time TP is obtained in advance through experiments or simulations, and a two-dimensional map of the basic injection time TP is created. It is stored in the ROM 45 of the circuit 35, and in step 107, this map is searched to calculate the basic injection time TP according to the relative pressure correction value Pdl and the engine speed NE at that time. The processing in step 107 serves as basic injection amount calculation means in the claims.
[0022]
After calculating the basic injection time TP, in step 108, an injection amount correction coefficient KPad corresponding to the atmospheric pressure Pa is calculated. In this calculation method, the relationship between the atmospheric pressure Pa and the injection amount correction coefficient KPad is obtained in advance through experiments or simulations, and the relationship is stored in the ROM 45 of the engine control circuit 35 as map data (see FIG. 4) for detection. An injection amount correction coefficient KPad corresponding to the atmospheric pressure Pa is obtained by searching map data. The map data of the injection amount correction coefficient KPad is finely set in the vicinity of the reference atmospheric pressure that is the normal range.
[0023]
In the next step 109, various correction coefficients K other than the injection amount correction coefficient KPad are calculated. For example, various corrections such as a warm-up increase correction coefficient according to the output signal (cooling water temperature) of the water temperature sensor 31, an increase correction coefficient after startup, an intake air temperature correction coefficient according to the output signal (intake air temperature) of the intake air temperature sensor 14, etc. The coefficient K is calculated.
[0024]
Thereafter, in step 110, the response delay time of the fuel injection valve 18, that is, the invalid injection time TV is calculated based on the power supply voltage, and in step 111, the pulse width of the injection pulse output to the fuel injection valve 18 is obtained. The final injection time TAU is calculated by the following equation using the basic injection time TP, the injection amount correction coefficient KPad, various correction coefficients K, and the invalid injection time TV.
TAU = TP × KPad × K + TV
Here, the correction coefficient K includes various correction coefficients such as a warm-up increase correction coefficient, a post-startup increase correction coefficient, and an intake air temperature correction coefficient. The processing in step 111 serves as final injection amount calculation means in the claims.
[0025]
According to the present embodiment described above, both the process of calculating the basic injection time TP from the relative pressure (Pa-Pb) and the process of calculating the final injection time TAU from the basic injection time TP both have the atmospheric pressure Pa. Since both the basic injection time TP and the final injection time TAU are corrected using the corresponding correction coefficients KPa and KPad, only one of the basic injection time TP and the final injection time TAU is changed according to the atmospheric pressure Pa as in the prior art. As compared with the case of correcting, the final injection time TAU can be calculated with high accuracy, and exhaust emission reduction and drivability improvement can be realized.
[0026]
Further, according to the present embodiment, the map data of the relative pressure correction coefficient KPa and the map data of the injection amount correction coefficient KPad are set finely in the vicinity of the reference atmospheric pressure, which is the normal range, so that the map data of the normal pressure range is large. The relative pressure correction coefficient KPa and the injection amount correction coefficient KPad can be accurately obtained according to the change in the atmospheric pressure Pa, and the calculation accuracy of the final injection time TAU in the normal range can be improved.
[0027]
However, according to the present invention, the map data of the relative pressure correction coefficient KPa and the map data of the injection amount correction coefficient KPad do not necessarily need to be set finely in the vicinity of the reference atmospheric pressure (normal range). The interval may be the same as the set interval of other regions, and even in this case, the intended purpose of the present invention can be sufficiently achieved.
[0028]
In this embodiment, the relative pressure correction coefficient KPa and the injection amount correction coefficient KPad are both obtained from a one-dimensional map using the atmospheric pressure Pa as a parameter, but the atmospheric pressure Pa and the engine speed NE are used as parameters. It may be obtained from a two-dimensional map.
[0029]
In the present embodiment, the relative pressure is the differential pressure between the bottom pressure Pb of the intake pressure and the atmospheric pressure Pa, but may be the differential pressure between the average value of the intake pressure (average intake pressure) and the atmospheric pressure Pa.
Relative pressure = Atmospheric pressure Pa-Average intake pressure [0030]
In the present embodiment, the basic injection time TP is calculated based on the relative pressure correction value Pdl and the engine speed NE in the entire operation region. However, for example, the relative pressure correction value Pdl is calculated only in the low load region. The basic injection time TP may be calculated based on the engine speed NE, and the basic injection time TP may be calculated based on the throttle opening and the engine speed NE in the middle load / high load region.
[0031]
In this embodiment, the atmospheric pressure Pa is detected by the atmospheric pressure sensor 32. However, the output value of the intake pressure sensor 17 immediately after the engine is started or the output value of the intake pressure sensor 17 after a predetermined time has elapsed since the engine is stopped is the atmospheric pressure. Pa may be taken into the engine control circuit 35 and stored in a backup RAM (not shown), and this stored value may be used as the atmospheric pressure Pa. In this case, the atmospheric pressure sensor 32 becomes unnecessary.
In addition, the present invention is not limited to a two-wheeled vehicle, but can be applied to a four-wheeled vehicle.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an entire engine control system showing an embodiment of the present invention. FIG. 2 is a flowchart showing a flow of processing of a fuel injection control routine. FIG. 3 conceptually shows a map of a relative pressure correction coefficient KPa. FIG. 4 is a diagram conceptually showing a map of an injection amount correction coefficient KPad. FIG. 5 is a time chart showing the behavior of intake pressure.
DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake manifold, 13 ... Air box, 15 ... Throttle valve, 16 ... Throttle opening sensor, 17 ... Intake pressure sensor (intake pressure detection means), 18 ... Fuel injection valve, 29 ... Engine rotational speed sensor (rotational speed detection means), 32 ... atmospheric pressure sensor (atmospheric pressure detection means), 35 ... engine control circuit (basic injection amount calculation means, final injection amount calculation means), 45 ... ROM (storage means).

Claims (4)

内燃機関回転数を検出する回転数検出手段と、大気圧を検出する大気圧検出手段と、吸気圧を検出する吸気圧検出手段とを備え、これら各検出手段で検出した吸気圧と大気圧との差圧（以下「相対圧」という）と内燃機関回転数とに基づいて燃料噴射量を算出するようにした内燃機関の燃料噴射制御装置において、
前記相対圧を大気圧に応じた相対圧補正係数により基準大気圧状態での相対圧に補正する相対圧補正手段と、
補正後の相対圧と内燃機関回転数とに基づいて基本噴射量を算出する基本噴射量算出手段と、
前記基本噴射量を大気圧に応じた噴射量補正係数で補正して燃料噴射量を求める最終噴射量算出手段と
を備え、
前記相対圧補正手段は、基準大気圧を検出大気圧で割り算した値を前記相対圧補正係数として用いることを特徴とする内燃機関の燃料噴射制御装置。An engine speed detecting means for detecting the engine speed, an atmospheric pressure detecting means for detecting the atmospheric pressure, and an intake pressure detecting means for detecting the intake pressure, the intake pressure and the atmospheric pressure detected by each of the detecting means A fuel injection control device for an internal combustion engine that calculates a fuel injection amount based on a differential pressure (hereinafter referred to as "relative pressure") and an internal combustion engine speed,
A relative pressure correction means for correcting the relative pressure to a relative pressure in a reference atmospheric pressure state by a relative pressure correction coefficient corresponding to the atmospheric pressure;
Basic injection amount calculating means for calculating a basic injection amount based on the corrected relative pressure and the internal combustion engine speed;
A final injection amount calculating means for correcting the basic injection amount with an injection amount correction coefficient corresponding to atmospheric pressure to obtain a fuel injection amount ;
A fuel injection control device for an internal combustion engine, wherein the relative pressure correction means uses a value obtained by dividing a reference atmospheric pressure by a detected atmospheric pressure as the relative pressure correction coefficient . 前記相対圧補正係数のマップデータと前記噴射量補正係数のマップデータを記憶する記憶手段を備え、
前記相対圧補正係数のマップデータと前記噴射量補正係数のマップデータは、基準大気圧付近で細かくデータを設定していることを特徴とする請求項１に記載の内燃機関の燃料噴射制御装置。Storage means for storing map data of the relative pressure correction coefficient and map data of the injection amount correction coefficient;
2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the map data of the relative pressure correction coefficient and the map data of the injection amount correction coefficient are set finely near a reference atmospheric pressure. 吸気圧と大気圧との差圧（以下「相対圧」という）と内燃機関回転数とに基づいて燃料噴射量を算出する内燃機関の燃料噴射制御方法において、
前記相対圧を大気圧に応じた相対圧補正係数により基準大気圧状態での相対圧に補正し、補正後の相対圧と内燃機関回転数とに基づいて基本噴射量を算出した後、この基本噴射量を大気圧に応じた噴射量補正係数で補正して燃料噴射量を求めることを特徴とする内燃機関の燃料噴射制御方法。In a fuel injection control method for an internal combustion engine that calculates a fuel injection amount based on a differential pressure (hereinafter referred to as “relative pressure”) between an intake pressure and atmospheric pressure and an internal combustion engine speed,
The relative pressure is corrected to a relative pressure in a reference atmospheric pressure state by a relative pressure correction coefficient corresponding to the atmospheric pressure, and a basic injection amount is calculated based on the corrected relative pressure and the internal combustion engine speed, and then the basic pressure is calculated. A fuel injection control method for an internal combustion engine, wherein the fuel injection amount is obtained by correcting the injection amount with an injection amount correction coefficient according to atmospheric pressure. 内燃機関回転数を検出する回転数検出手段と、
大気圧を検出する大気圧検出手段と、
吸気圧を検出する吸気圧検出手段とを備え、
これら各検出手段で検出した吸気圧と大気圧との差圧（以下「相対圧」という）と内燃機関回転数とに基づいて燃料噴射量を算出するようにした内燃機関の燃料噴射制御装置において、
前記相対圧を大気圧に応じた相対圧補正係数により基準大気圧状態での相対圧に補正する相対圧補正手段と、
補正後の相対圧と内燃機関回転数とに基づいて基本噴射量を算出する基本噴射量算出手段と、
前記基本噴射量を大気圧に応じた噴射量補正係数で補正して燃料噴射量を求める最終噴射量算出手段と、
前記相対圧補正係数のマップデータを記憶する記憶手段とを備え、
前記相対圧補正手段は、前記記憶手段に記憶されている前記マップデータに基づいて前記相対圧補正係数を設定することを特徴とする内燃機関の燃料噴射制御装置。A rotational speed detecting means for detecting the rotational speed of the internal combustion engine;
Atmospheric pressure detection means for detecting atmospheric pressure;
An intake pressure detecting means for detecting the intake pressure,
In a fuel injection control device for an internal combustion engine that calculates a fuel injection amount based on a differential pressure (hereinafter referred to as “relative pressure”) between the intake pressure and the atmospheric pressure detected by each of these detection means and the internal combustion engine speed. ,
A relative pressure correction means for correcting the relative pressure to a relative pressure in a reference atmospheric pressure state by a relative pressure correction coefficient corresponding to the atmospheric pressure;
Basic injection amount calculating means for calculating a basic injection amount based on the corrected relative pressure and the internal combustion engine speed;
Final injection amount calculating means for correcting the basic injection amount with an injection amount correction coefficient corresponding to atmospheric pressure to obtain a fuel injection amount;
Storage means for storing map data of the relative pressure correction coefficient,
The fuel injection control device for an internal combustion engine, wherein the relative pressure correction means sets the relative pressure correction coefficient based on the map data stored in the storage means.
JP09183397A 1997-04-10 1997-04-10 Fuel injection control device and fuel injection control method for internal combustion engine Expired - Lifetime JP3838526B2 (en)

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