JP4378665B2 - Control device and control method for internal combustion engine - Google Patents

Control device and control method for internal combustion engine Download PDF

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JP4378665B2
JP4378665B2 JP2000055919A JP2000055919A JP4378665B2 JP 4378665 B2 JP4378665 B2 JP 4378665B2 JP 2000055919 A JP2000055919 A JP 2000055919A JP 2000055919 A JP2000055919 A JP 2000055919A JP 4378665 B2 JP4378665 B2 JP 4378665B2
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amount
fuel
cylinder
target
fuel injection
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JP2001241343A (en
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平樹 松本
衛 馬渕
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Denso Corp
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Denso Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/04—Introducing corrections for particular operating conditions
    • F02D41/047—Taking into account fuel evaporation or wall wetting
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2250/00—Engine control related to specific problems or objectives
    • F02D2250/12—Timing of calculation, i.e. specific timing aspects when calculation or updating of engine parameter is performed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2250/00—Engine control related to specific problems or objectives
    • F02D2250/18—Control of the engine output torque
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2250/00—Engine control related to specific problems or objectives
    • F02D2250/18—Control of the engine output torque
    • F02D2250/21—Control of the engine output torque during a transition between engine operation modes or states

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、運転者の要求する要求トルクを判断して内燃機関の運転を制御する内燃機関の制御装置及び制御方法に関するものである。
【０００２】
【従来の技術】
近年の電子制御化された自動車のエンジン制御においては、運転者のアクセル操作に即応した応答性の良いドライバビリティを実現するために、運転者が操作したアクセル開度、エンジン回転速度等から運転者の要求する加速力（トルク）を判断して、スロットル開度、燃料噴射量、点火時期等を運転者の要求するトルクに応じて制御する、いわゆるトルクディマンド制御を行うようにしたものがある。従来のトルクディマンド制御は、エンジンへの要求トルクと目標空燃比を同時に満たすために、要求トルクから決まる目標空燃比に基づいてスロットル開度を制御し、一方、吸入空気量と目標空燃比から決まる目標燃料量に基づいて燃料噴射量を制御するようにしていた（特開平９−２８７５１３号公報参照）。
【０００３】
【発明が解決しようとする課題】
しかし、従来のトルクディマンド制御では、負荷が急変するような過渡状態において、筒内充填空気量が確定するタイミングと、目標空燃比と吸入空気量に基づいて燃料噴射量を決定するタイミングとの時間ずれに伴なう誤差が生じて、実際の筒内充填空気量と筒内流入燃料量との比（空燃比）が目標空燃比からずれてしまい、過渡時の空燃比の制御精度が悪くなるという欠点があった。
【０００４】
つまり、筒内充填空気量は吸気弁閉タイミングまで確定しないため、筒内充填空気量確定タイミングは、燃料噴射量決定タイミング（吸気弁開タイミングの直前）よりもかなり遅れる。しかも、スロットル開度の指令値を電子スロットルに出力してから実際にスロットル開度が変化して筒内充填空気量が変化するまでには、スロットルバルブの応答遅れと吸入空気の流動遅れがある。一方、筒内流入燃料量は、空気系壁面付着燃料（ウエット）等による燃料輸送遅れの影響を受ける。この燃料輸送遅れやスロットルバルブの応答遅れの影響は、過渡時に大きくなるため、過渡時に筒内充填空気量と筒内流入燃料量との比（空燃比）が目標空燃比からずれてしまう。
【０００５】
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、トルクディマンド制御システムにおいて、過渡時でも精度の良い空燃比制御を行うことができる内燃機関の制御装置及び制御方法を提供することにある。
【０００６】
【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は、内燃機関の各気筒の吸気ポート近傍に燃料を噴射する燃料噴射弁が取り付けられ、規範モデル演算手段によって、要求トルクに基づいて目標筒内充填空気量の規範モデルを演算し、目標筒内流入燃料量演算手段によって該規範モデルと目標空燃比に基づいて目標筒内流入燃料量を演算すると共に、燃料噴射制御手段によって空気系壁面付着燃料等による燃料輸送遅れを考慮して実際の筒内流入燃料量が目標筒内流入燃料量と一致するように前記燃料噴射弁から噴射する燃料噴射量を決定し、スロットル開度指令値演算手段によって、少なくとも目標筒内充填空気量の規範モデルと内燃機関回転速度に基づいてスロットル開度の指令値を演算する。更に、スロットル制御手段は、図４（ａ）に示すように燃料噴射量決定タイミングから筒内充填空気量及び筒内流入燃料量が確定する吸気弁閉タイミングまでの遅れ時間（Ｚ-L）と該遅れ時間（Ｚ-L）よりも短い時間であるスロットルバルブの応答遅れ時間（Ｚ-m）との時間ずれ分（Ｚ-(L-m)）だけ前記スロットル開度の指令値の位相を前記燃料噴射量決定タイミングから遅らせてスロットルバルブを駆動することで、実際の筒内充填空気量が規範モデルを吸気弁閉タイミングまでの遅れ時間分（Ｚ-L）だけ位相を遅らせて得られる目標筒内充填空気量に一致するようにスロットル開度を制御する。このようにすれば、トルクディマンド制御システムにおいて、空気系の動特性、燃料輸送系の動特性及び燃料噴射量決定から筒内充填空気量確定（吸気弁閉タイミング）までの時間遅れを考慮して、筒内充填空気量と筒内流入燃料量の制御を同期させることができ、常に実際の筒内充填空気量と筒内流入燃料量との比（空燃比）を目標空燃比に一致させることができる。これにより、過渡時でも精度の良い空燃比制御を行うことができて、加速応答性を向上できると共に、排気エミッションを低減できる。
【０００７】
この場合、請求項２のように、要求トルクをなまし処理（一次遅れ処理）した値に基づいて目標筒内充填空気量の規範モデルを設定するようにすると良い。このようにすれば、簡単な演算処理により、目標筒内充填空気量の規範モデルを設定することができる。
【０００８】
【発明の実施の形態】
以下、本発明の一実施形態を図面に基づいて説明する。まず、図１に基づいてエンジン制御システム全体の概略構成を説明する。内燃機関であるエンジン１１の吸気管１２の最上流部には、エアクリーナ１３が設けられ、このエアクリーナ１３の下流側には、吸入空気量を検出するエアフローメータ１４が設けられている。このエアフローメータ１４の下流側には、モータ（図示せず）等によって駆動されるスロットルバルブ１５と、スロットル開度を検出するスロットル開度センサ１６とが設けられている。
【０００９】
更に、スロットルバルブ１５の下流側には、サージタンク１７が設けられ、このサージタンク１７に、吸気管圧力を検出する吸気管圧力センサ１８が設けられている。また、サージタンク１７には、エンジン１１の各気筒に吸入空気を導入する吸気マニホールド１９が設けられ、各気筒の吸気マニホールド１９の吸気ポート近傍に、それぞれ燃料を噴射する燃料噴射弁２０が取り付けられている。
【００１０】
一方、エンジン１１の排気管２１の途中には、排ガス中のＣＯ，ＨＣ，ＮＯｘ等を浄化する三元触媒等の触媒２２が設置されている。この触媒２２の上流側には、排ガスの空燃比を検出する空燃比センサ２３（又は酸素センサ）が設けられている。また、エンジン１１のシリンダブロックには、冷却水温を検出する冷却水温センサ２４や、エンジン回転速度を検出するためのクランク角センサ２５が取り付けられている。また、アクセルペダルの開度（アクセル開度）を検出するアクセルセンサ２６が設けられている。
【００１１】
これら各種センサの出力は、エンジン制御回路（以下「ＥＣＵ」と表記する）２７に入力される。このＥＣＵ２７は、マイクロコンピュータを主体として構成され、内蔵されたＲＯＭ（記憶媒体）に記憶された図２のトルクディマンド制御プログラムを実行することで、燃料噴射量とスロットル開度を制御する。
【００１２】
吸気ポート噴射エンジン１１では、図３に示すように、吸気弁開タイミングの直前に燃料噴射量を決定して噴射セットを行い、吸気弁開タイミングの直前又は直後に、燃料噴射弁２０を駆動して燃料噴射を実行する。噴射した燃料が実際に筒内に流入するまでの燃料輸送系には、空気系壁面付着燃料（ウエット）等による燃料輸送遅れがあるため、筒内流入燃料量は、燃料噴射タイミングから遅れて変化する。また、筒内充填空気量は吸気弁閉タイミングまで確定しないため、筒内充填空気量確定タイミングは、燃料噴射量決定タイミング（吸気弁開タイミングの直前）よりもかなり遅れる。しかも、スロットル開度の指令値を電子スロットルに出力してから実際にスロットル開度が変化して筒内充填空気量が変化するまでには、スロットルバルブの応答遅れと吸入空気の流動遅れがある。
【００１３】
このような空気系の動特性、燃料輸送系の動特性及び燃料噴射量決定から筒内充填空気量確定（吸気弁閉タイミング）までの時間遅れの影響は、過渡時に大きくなるため、これらの影響を考慮しないと、過渡時に筒内充填空気量と筒内流入燃料量との比（空燃比）が目標空燃比からずれてしまう。
【００１４】
そこで、本実施形態では、図４（ａ）に示すように、要求トルクに基づいて目標筒内充填空気量の規範モデルを演算し、この規範モデルと目標空燃比に基づいて目標筒内流入燃料量を演算すると共に、空気系壁面付着燃料等による燃料輸送遅れを考慮して実際の筒内流入燃料量が目標筒内流入燃料量と一致するように燃料噴射弁２０から噴射する燃料噴射量を決定し、更に、目標筒内充填空気量の規範モデルとエンジン回転速度等に基づいてスロットル開度の指令値を演算する。そして、燃料噴射量決定タイミングから吸気弁閉タイミングまでの遅れ時間（Ｚ-L）とスロットルバルブ１５の応答遅れ時間（Ｚ-m）との時間ずれ分（Ｚ-(L-m)）だけ前記スロットル開度の指令値の位相を前記燃料噴射量決定タイミングから遅らせてスロットルバルブ１５を駆動することで、実際の筒内充填空気量が上記規範モデルを吸気弁閉タイミングまでの遅れ時間分（Ｚ-L）だけ位相を遅らせて得られる目標筒内充填空気量に一致するようにスロットル開度を制御する。
【００１５】
以下、この制御を実行する図２のトルクディマンド制御プログラムの処理内容を説明する。まず、ステップ１０１で、アクセルセンサ２６の出力からアクセル開度を検出し、次のステップ１０２で、このアクセル開度に基づいて要求トルクを算出する。この際、アクセル開度の他に、エンジン回転速度や車速等も考慮して要求トルクを算出するようにしても良い。
【００１６】
この後、ステップ１０３で、要求トルクをなまし処理（一次遅れ処理）した後、ステップ１０４で、要求トルクをなまし処理した値に所定のゲインを乗算して、目標筒内充填空気量の規範モデルを演算する。これらステップ１０３，１０４の処理が特許請求の範囲でいう規範モデル演算手段に相当する役割を果たす。
【００１７】
規範モデルの演算後、ステップ１０５に進み、筒内流入燃料量と筒内充填空気量とを同期させるためのタイミング同期ディレイ時間（Ｚ-(L-m)）をエンジン回転速度、吸入空気量等に応じてマップ等により設定する。ここで、タイミング同期ディレイ時間（Ｚ-(L-m)）は、燃料噴射量決定タイミングから吸気弁閉タイミングまでの遅れ時間（Ｚ-L）とスロットルバルブ１５の応答遅れ時間（Ｚ-m）との時間ずれ分に相当する。スロットルバルブ１５の応答遅れ時間（Ｚ-m）は、スロットル開度の指令値を電子スロットルに出力してから実際にスロットル開度が変化するまでの遅れ時間である。
【００１８】
この後、ステップ１０６で、目標筒内充填空気量の規範モデルやエンジン回転速度等に基づいてスロットル開度指令値を演算し、次のステップ１０７で、このスロットル開度指令値に応じた制御信号を、燃料噴射量決定タイミングからタイミング同期ディレイ時間（Ｚ-(L-m)）だけ遅らせて電子スロットルのモータに出力し、スロットルバルブ１５を駆動してスロットル開度を制御する。上記ステップ１０６の処理が特許請求の範囲でいうスロットル開度指令値演算手段に相当する役割を果たし、ステップ１０５と１０７の処理が特許請求の範囲でいうスロットル制御手段に相当する役割を果たす。
【００１９】
一方、燃料噴射量の制御は、ステップ１０８で、要求トルクとエンジン回転速度に基づいて目標空燃比をマップ等により設定し、次のステップ１０９で、目標筒内充填空気量を目標空燃比で割り算して目標筒内流入燃料量を求める。このステップ１０９の処理が特許請求の範囲でいう目標筒内流入燃料量演算手段に相当する役割を果たす。
【００２０】
この後、ステップ１１０で、空気系壁面付着燃料等による燃料輸送遅れを考慮するための燃料輸送遅れ補正係数を算出する。また、ステップ１１１で、空燃比センサ２３の出力から実空燃比を検出し、次のステップ１１２で、実空燃比と目標空燃比との偏差に応じて空燃比フィードバック補正係数を算出する。
【００２１】
この後、ステップ１１３で、目標筒内流入燃料量に、燃料輸送遅れ補正係数、空燃比フィードバック補正係数、水温補正係数等を乗算して最終的な燃料噴射量を求める。そして、次のステップ１１４で、この燃料噴射量に応じたパルス幅の噴射パルスを燃料噴射弁２０に出力して燃料を噴射する。これらステップ１１０〜１１４の処理が特許請求の範囲でいう燃料噴射制御手段に相当する役割を果たす。
【００２２】
以上説明した本実施形態では、図４（ａ）に示すように、要求トルクに基づいて目標筒内充填空気量の規範モデルを演算し、この規範モデルと目標空燃比に基づいて目標筒内流入燃料量を演算すると共に、空気系壁面付着燃料等による燃料輸送遅れを考慮して実際の筒内流入燃料量が目標筒内流入燃料量と一致するように燃料噴射量を決定し、更に、目標筒内充填空気量の規範モデルとエンジン回転速度等に基づいてスロットル開度の指令値を演算し、燃料噴射量決定タイミングから筒内充填空気量及び筒内流入燃料量が確定する吸気弁閉タイミングまでの遅れ時間（Ｚ-L）とスロットルバルブ１５の応答遅れ時間（Ｚ-m）との時間ずれ分（Ｚ-(L-m)）だけ前記スロットル開度指令値の位相を前記燃料噴射量決定タイミングから遅らせてスロットルバルブ１５を駆動するようにしたので、空気系の動特性、燃料輸送系の動特性及び燃料噴射量決定から筒内充填空気量確定（吸気弁閉タイミング）までの時間遅れを考慮して、筒内充填空気量と筒内流入燃料量の制御を同期させることができ、常に実際の筒内充填空気量と筒内流入燃料量との比（空燃比）を目標空燃比に一致させることができる。これにより、過渡時でも精度の良い空燃比制御を行うことができて、加速応答性を向上できると共に、排気エミッションを低減できる。
【００２３】
これに対し、図４（ｂ）に示す比較例では、燃料噴射量決定タイミングから吸気弁閉タイミングまでの遅れ時間（Ｚ-L）とスロットルバルブ１５の応答遅れ時間（Ｚ-m）との時間ずれ分が考慮されておらず、燃料噴射量とスロットル開度指令値の位相が同期しているため、過渡時の筒内充填空気量と筒内流入燃料量との比（空燃比）が、両者のタイミングのずれにより、目標空燃比からずれてしまい、過渡時の空燃比の制御精度が悪くなる。
【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】トルクディマンド制御の概要を説明するフローチャート
【図３】エンジンのサイクルと筒内流入燃料量と筒内充填空気量との関係を説明するタイムチャート
【図４】（ａ）は本発明の一実施形態の制御方法を説明する図、（ｂ）は比較例の制御方法を説明する図
【符号の説明】
１１…エンジン（内燃機関）、１２…吸気管、１４…エアフローメータ、１５…スロットルバルブ、１８…吸気管圧力センサ、２０…燃料噴射弁、２５…クランク角センサ、２６…アクセルセンサ、２７…ＥＣＵ（規範モデル演算手段，目標筒内流入燃料量演算手段，燃焼噴射制御手段，スロットル制御手段）。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device and a control method for an internal combustion engine that controls operation of the internal combustion engine by determining a required torque requested by a driver.
[0002]
[Prior art]
In recent automobile engine control that has been electronically controlled, in order to realize responsive drivability that responds quickly to the driver's accelerator operation, the driver determines the driver's accelerator opening, engine speed, etc. In other cases, so-called torque demand control is performed in which the acceleration force (torque) required by the vehicle is determined and the throttle opening, fuel injection amount, ignition timing, and the like are controlled according to the torque required by the driver. In the conventional torque demand control, the throttle opening is controlled based on the target air-fuel ratio determined from the required torque in order to satisfy the required torque to the engine and the target air-fuel ratio at the same time, while determined from the intake air amount and the target air-fuel ratio. The fuel injection amount is controlled based on the target fuel amount (see Japanese Patent Laid-Open No. 9-287513).
[0003]
[Problems to be solved by the invention]
However, in the conventional torque demand control, in a transient state in which the load changes suddenly, the time between the timing at which the in-cylinder charged air amount is determined and the timing at which the fuel injection amount is determined based on the target air-fuel ratio and the intake air amount. An error due to the deviation occurs, and the ratio (air-fuel ratio) between the actual cylinder air charge amount and the cylinder inflow fuel amount deviates from the target air-fuel ratio, and the control accuracy of the air-fuel ratio at the time of transition deteriorates. There was a drawback.
[0004]
That is, since the cylinder charge air amount is not determined until the intake valve closing timing, the cylinder charge air amount determination timing is considerably delayed from the fuel injection amount determination timing (immediately before the intake valve opening timing). Moreover, there is a response delay of the throttle valve and a flow delay of the intake air from when the command value of the throttle opening is output to the electronic throttle until the throttle opening actually changes and the in-cylinder charged air amount changes. . On the other hand, the in-cylinder inflow fuel amount is affected by fuel transportation delay due to air system wall surface attached fuel (wet) or the like. Since the influence of the fuel transport delay and the throttle valve response delay becomes large during the transition, the ratio (air-fuel ratio) between the in-cylinder charged air amount and the in-cylinder inflow fuel amount deviates from the target air-fuel ratio during the transition.
[0005]
The present invention has been made in consideration of such circumstances, and therefore, the object of the present invention is to provide a control device and control method for an internal combustion engine that can perform accurate air-fuel ratio control even in a transient state in a torque demand control system. Is to provide.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the first and third aspects of the present invention, a fuel injection valve for injecting fuel is attached in the vicinity of the intake port of each cylinder of the internal combustion engine, and based on the required torque by the reference model calculation means. A reference model of the target in-cylinder charged air amount is calculated, the target in-cylinder inflow fuel amount calculation means calculates the target in-cylinder inflow fuel amount based on the reference model and the target air-fuel ratio, and the fuel injection control means calculates the air system. In consideration of fuel transportation delay due to fuel adhering to the wall, etc., the fuel injection amount to be injected from the fuel injection valve is determined so that the actual in-cylinder inflow fuel amount matches the target in-cylinder inflow fuel amount, and the throttle opening command value The calculation means calculates a command value for the throttle opening based on at least the reference model of the target cylinder charge air amount and the internal combustion engine rotational speed. Further, as shown in FIG. 4 (a), the throttle control means performs a delay time (Z −L ) from the fuel injection amount determination timing to the intake valve closing timing at which the cylinder charge air amount and the cylinder inflow fuel amount are determined. slow-is time (Z -L) throttle valve response delay time is shorter than the (Z -m) and the time shift amount (Z - (Lm)) only the fuel phase of the command value of the throttle opening The target in-cylinder obtained by delaying the phase by the delay time (Z -L ) from the reference model to the intake valve closing timing by driving the throttle valve with a delay from the injection amount determination timing The throttle opening is controlled so as to match the amount of charge air. In this way, in the torque demand control system, taking into account the time delay from the determination of the air system dynamic characteristics, the fuel transport system dynamic characteristics, and the fuel injection amount determination to the cylinder charge air amount determination (intake valve closing timing). The control of the in-cylinder charged air amount and the in-cylinder inflow fuel amount can be synchronized, and the ratio between the actual in-cylinder charged air amount and the in-cylinder inflow fuel amount (air-fuel ratio) is always matched with the target air-fuel ratio. Can do. Thus, accurate air-fuel ratio control can be performed even during a transition, acceleration response can be improved, and exhaust emission can be reduced.
[0007]
In this case, it is preferable to set a reference model of the target cylinder air charge amount based on a value obtained by smoothing the required torque (first-order lag process). In this way, the reference model of the target cylinder air charge amount can be set by a simple calculation process.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 which is an internal combustion engine, and an air flow meter 14 for detecting the intake air amount is provided downstream of the air cleaner 13. On the downstream side of the air flow meter 14, a throttle valve 15 driven by a motor (not shown) and the like, and a throttle opening sensor 16 for detecting the throttle opening are provided.
[0009]
Further, a surge tank 17 is provided on the downstream side of the throttle valve 15, and an intake pipe pressure sensor 18 for detecting the intake pipe pressure is provided in the surge tank 17. The surge tank 17 is provided with an intake manifold 19 for introducing intake air to each cylinder of the engine 11, and a fuel injection valve 20 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 19 of each cylinder. ing.
[0010]
On the other hand, a catalyst 22 such as a three-way catalyst for purifying CO, HC, NOx, etc. in the exhaust gas is installed in the middle of the exhaust pipe 21 of the engine 11. An air-fuel ratio sensor 23 (or oxygen sensor) that detects the air-fuel ratio of the exhaust gas is provided on the upstream side of the catalyst 22. A cooling water temperature sensor 24 for detecting the cooling water temperature and a crank angle sensor 25 for detecting the engine rotation speed are attached to the cylinder block of the engine 11. Further, an accelerator sensor 26 for detecting the opening degree of the accelerator pedal (accelerator opening degree) is provided.
[0011]
Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 27. The ECU 27 is mainly composed of a microcomputer, and controls the fuel injection amount and the throttle opening by executing the torque demand control program of FIG. 2 stored in a built-in ROM (storage medium).
[0012]
In the intake port injection engine 11, as shown in FIG. 3, the fuel injection amount is determined immediately before the intake valve opening timing to perform injection setting, and the fuel injection valve 20 is driven immediately before or after the intake valve opening timing. To perform fuel injection. In the fuel transportation system until the injected fuel actually flows into the cylinder, there is a fuel transportation delay due to air system wall-attached fuel (wet), etc., so the in-cylinder inflow fuel amount changes with a delay from the fuel injection timing. To do. Further, since the in-cylinder charged air amount is not determined until the intake valve closing timing, the in-cylinder charged air amount determining timing is considerably delayed from the fuel injection amount determining timing (immediately before the intake valve opening timing). Moreover, there is a response delay of the throttle valve and a flow delay of the intake air from when the command value of the throttle opening is output to the electronic throttle until the throttle opening actually changes and the in-cylinder charged air amount changes. .
[0013]
The effects of the time delay from the determination of the air system dynamic characteristics, the fuel transport system dynamic characteristics, and the determination of the fuel injection amount to the determination of the in-cylinder charged air amount (intake valve closing timing) increase during transients. If this is not taken into consideration, the ratio (air-fuel ratio) between the in-cylinder charged air amount and the in-cylinder inflow fuel amount will deviate from the target air-fuel ratio at the time of transition.
[0014]
Therefore, in the present embodiment, as shown in FIG. 4A, a reference model of the target cylinder charge air amount is calculated based on the required torque, and the target cylinder inflow fuel is calculated based on the reference model and the target air-fuel ratio. The fuel injection amount to be injected from the fuel injection valve 20 is calculated so that the actual in-cylinder inflow fuel amount coincides with the target in-cylinder inflow fuel amount in consideration of the fuel transportation delay due to the fuel attached to the air system wall and the like. Further, the throttle opening command value is calculated based on the reference model of the target cylinder charge air amount, the engine speed, and the like. Then, the fuel injection amount determining timing delay time until the intake valve closing timing (Z -L) and the time shift amount of the response delay time of the throttle valve 15 (Z -m) (Z - (Lm)) only the throttle opening When the throttle valve 15 is driven by delaying the phase of the command value of the degree from the fuel injection amount determination timing, the actual cylinder air charge amount becomes equal to the delay time (Z −L ), The throttle opening is controlled so as to coincide with the target in-cylinder charged air amount obtained by delaying the phase.
[0015]
The processing contents of the torque demand control program shown in FIG. 2 for executing this control will be described below. First, in step 101, the accelerator opening is detected from the output of the accelerator sensor 26, and in the next step 102, the required torque is calculated based on the accelerator opening. At this time, the required torque may be calculated in consideration of the engine rotation speed, the vehicle speed, and the like in addition to the accelerator opening.
[0016]
Then, after the required torque is smoothed (first-order lag processing) in step 103, the value obtained by smoothing the required torque is multiplied by a predetermined gain in step 104, and the target in-cylinder charged air amount is determined. Calculate the model. The processing of these steps 103 and 104 plays a role corresponding to the normative model calculation means in the claims.
[0017]
After the calculation of the reference model, the routine proceeds to step 105, where the timing synchronization delay time (Z- (Lm) ) for synchronizing the in-cylinder inflow fuel amount and the in-cylinder charged air amount is determined according to the engine speed, the intake air amount, etc. Set by map. Here, the timing synchronization delay time (Z- (Lm) ) is the delay time (Z -L ) from the fuel injection amount determination timing to the intake valve closing timing and the response delay time (Z -m ) of the throttle valve 15. It corresponds to the time difference. The response delay time (Z −m ) of the throttle valve 15 is a delay time from when the throttle opening command value is output to the electronic throttle until the throttle opening actually changes.
[0018]
Thereafter, in step 106, a throttle opening command value is calculated based on the reference model of the target cylinder charge air amount, the engine speed, etc., and in the next step 107, a control signal corresponding to the throttle opening command value is calculated. Is delayed from the fuel injection amount determination timing by the timing synchronization delay time (Z- (Lm) ) and output to the motor of the electronic throttle, and the throttle valve 15 is driven to control the throttle opening. The process of step 106 plays a role corresponding to the throttle opening command value calculation means in the claims, and the processes of steps 105 and 107 play a role corresponding to the throttle control means in the claims.
[0019]
On the other hand, in the control of the fuel injection amount, in step 108, the target air-fuel ratio is set by a map or the like based on the required torque and the engine speed, and in the next step 109, the target in-cylinder charged air amount is divided by the target air-fuel ratio. Thus, the target in-cylinder inflow fuel amount is obtained. The processing of this step 109 plays a role corresponding to the target in-cylinder inflow fuel amount calculation means in the claims.
[0020]
Thereafter, in step 110, a fuel transport delay correction coefficient for taking into account the fuel transport delay due to the air system wall surface attached fuel or the like is calculated. In step 111, the actual air-fuel ratio is detected from the output of the air-fuel ratio sensor 23, and in the next step 112, an air-fuel ratio feedback correction coefficient is calculated according to the deviation between the actual air-fuel ratio and the target air-fuel ratio.
[0021]
Thereafter, in step 113, a final fuel injection amount is obtained by multiplying the target in-cylinder inflow fuel amount by a fuel transport delay correction coefficient, an air-fuel ratio feedback correction coefficient, a water temperature correction coefficient, and the like. In the next step 114, an injection pulse having a pulse width corresponding to the fuel injection amount is output to the fuel injection valve 20 to inject fuel. The processing of these steps 110 to 114 plays a role corresponding to the fuel injection control means in the claims.
[0022]
In the present embodiment described above, as shown in FIG. 4A, a reference model of the target cylinder charge air amount is calculated based on the required torque, and the target cylinder inflow is calculated based on the reference model and the target air-fuel ratio. while calculating a fuel amount to determine the fuel injection amount so that the actual cylinder inflow fuel amount in consideration of the fuel transport delay due to the air system fuel deposited on the wall or the like coincides with the target cylinder inflow fuel amount, further, the target The intake valve closing timing at which the throttle opening command value is calculated based on the reference model of the in-cylinder charged air amount and the engine speed, and the in-cylinder charged air amount and in-cylinder inflow fuel amount are determined from the fuel injection amount determination timing delay time until (Z -L) and the time shift amount of the response delay time of the throttle valve 15 (Z -m) (Z - (Lm)) only the phase of the throttle opening command value the fuel injection amount determining timing Slow to delay Since the torque valve 15 is driven, the cylinder is considered in consideration of the time delay from the determination of the air system dynamic characteristics, the fuel transport system dynamic characteristics, and the fuel injection amount determination to the cylinder charge air amount determination (intake valve closing timing). The control of the in-cylinder air amount and the in-cylinder inflow fuel amount can be synchronized, and the ratio (air-fuel ratio) between the actual in-cylinder in-cylinder air amount and the in-cylinder inflow fuel amount can always be matched with the target air-fuel ratio. . Thus, accurate air-fuel ratio control can be performed even during a transition, acceleration response can be improved, and exhaust emission can be reduced.
[0023]
On the other hand, in the comparative example shown in FIG. 4B, the time between the delay time (Z −L ) from the fuel injection amount determination timing to the intake valve closing timing and the response delay time (Z −m ) of the throttle valve 15. Since the amount of deviation is not taken into account and the phase of the fuel injection amount and the throttle opening command value is synchronized, the ratio (air-fuel ratio) between the in-cylinder charged air amount and the in-cylinder inflow fuel amount at the time of transition is Due to the timing difference between the two, the air-fuel ratio deviates from the target air-fuel ratio, and the control accuracy of the air-fuel ratio at the time of transition deteriorates.
[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 explaining an outline of torque demand control. FIG. 3 is an engine cycle, in-cylinder inflow fuel amount, and in-cylinder filling. FIG. 4A is a diagram illustrating a control method according to an embodiment of the present invention, and FIG. 4B is a diagram illustrating a control method according to a comparative example.
DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 14 ... Air flow meter, 15 ... Throttle valve, 18 ... Intake pipe pressure sensor, 20 ... Fuel injection valve, 25 ... Crank angle sensor, 26 ... Accelerator sensor, 27 ... ECU (Standard model calculation means, target cylinder inflow fuel amount calculation means, combustion injection control means, throttle control means).

Claims (3)

内燃機関の各気筒の吸気ポート近傍に燃料を噴射する燃料噴射弁が取り付けられ、運転者の要求する要求トルクを判断して、その要求トルクに基づいて内燃機関の運転を制御する内燃機関の制御装置において、
前記要求トルクに基づいて目標筒内充填空気量の規範モデルを設定する規範モデル演算手段と、
前記目標筒内充填空気量の規範モデルと目標空燃比に基づいて目標筒内流入燃料量を演算する目標筒内流入燃料量演算手段と、
吸気系壁面付着燃料等による燃料輸送遅れを考慮して実際の筒内流入燃料量が前記目標筒内流入燃料量と一致するように前記燃料噴射弁から噴射する燃料噴射量を決定する燃料噴射制御手段と、
少なくとも前記目標筒内充填空気量の規範モデルと内燃機関回転速度に基づいてスロットル開度の指令値を演算するスロットル開度指令値演算手段と、
前記燃料噴射制御手段による燃料噴射量決定タイミングから筒内充填空気量及び筒内流入燃料量が確定する吸気弁閉タイミングまでの遅れ時間（Ｚ-L）と該遅れ時間（Ｚ-L）よりも短い時間であるスロットルバルブの応答遅れ時間（Ｚ-m）との時間ずれ分（Ｚ-(L-m)）だけ前記スロットル開度の指令値の位相を前記燃料噴射量決定タイミングから遅らせてスロットルバルブを駆動することで、実際の筒内充填空気量が前記規範モデルを前記吸気弁閉タイミングまでの遅れ時間分（Ｚ-L）だけ位相を遅らせて得られる目標筒内充填空気量に一致するようにスロットル開度を制御するスロットル制御手段と
を備えていることを特徴とする内燃機関の制御装置。Control of an internal combustion engine in which a fuel injection valve for injecting fuel is installed in the vicinity of an intake port of each cylinder of the internal combustion engine, and a required torque requested by a driver is determined and operation of the internal combustion engine is controlled based on the required torque In the device
A norm model calculation means for setting a norm model of the target cylinder charge air amount based on the required torque;
Target in-cylinder inflow fuel amount calculation means for calculating a target in-cylinder inflow fuel amount based on the reference model of the target in-cylinder charged air amount and the target air-fuel ratio;
Fuel injection control for determining the fuel injection amount to be injected from the fuel injection valve so that the actual in-cylinder inflow fuel amount matches the target in-cylinder inflow fuel amount in consideration of fuel transportation delay due to fuel adhering to the intake system wall surface, etc. Means,
Throttle opening command value calculation means for calculating a command value of the throttle opening based on at least a reference model of the target cylinder charge air amount and the internal combustion engine rotation speed;
It said fuel injection control means by the fuel injection amount determined in-cylinder charged air amount from timing and cylinder inflow fuel amount is delayed until the intake valve closing timing to determine the time (Z -L) and slow-is time (Z -L) than a short time the throttle valve response delay time (Z -m) and the time shift amount - the (Z (Lm)) only the throttle valve delays the phase of the command value of the throttle opening from said fuel injection amount determining timing By driving, the actual in-cylinder charged air amount matches the target in-cylinder charged air amount obtained by delaying the phase of the reference model by the delay time (Z- L ) until the intake valve closing timing. A control device for an internal combustion engine, comprising: throttle control means for controlling a throttle opening. 前記規範モデル演算手段は、前記要求トルクをなまし処理した値に基づいて前記目標筒内充填空気量の規範モデルを設定することを特徴とする請求項１に記載の内燃機関の制御装置。  2. The control device for an internal combustion engine according to claim 1, wherein the reference model calculation unit sets a reference model of the target cylinder charge air amount based on a value obtained by performing the smoothing process on the required torque. 内燃機関の各気筒の吸気ポート近傍に燃料を噴射する燃料噴射弁が取り付けられ、運転者の要求する要求トルクを判断して、その要求トルクに基づいて内燃機関の運転を制御する内燃機関の制御方法において、
前記要求トルクに基づいて目標筒内充填空気量の規範モデルを演算し、該規範モデルと目標空燃比に基づいて目標筒内流入燃料量を演算すると共に、吸気系壁面付着燃料等による燃料輸送遅れを考慮して実際の筒内流入燃料量が前記目標筒内流入燃料量と一致するように前記燃料噴射弁から噴射する燃料噴射量を決定し、更に、少なくとも前記目標筒内充填空気量の規範モデルと内燃機関回転速度に基づいてスロットル開度の指令値を演算し、 燃料噴射量決定タイミングから筒内充填空気量及び筒内流入燃料量が確定する吸気弁閉タイミングまでの遅れ時間（Ｚ-L）と該遅れ時間（Ｚ-L）よりも短い時間であるスロットルバルブの応答遅れ時間（Ｚ-m）との時間ずれ分（Ｚ-(L-m)）だけ前記スロットル開度の指令値の位相を前記燃料噴射量決定タイミングから遅らせてスロットルバルブを駆動することで、実際の筒内充填空気量が前記規範モデルを前記吸気弁閉タイミングまでの遅れ時間分（Ｚ-L）だけ位相を遅らせて得られる目標筒内充填空気量に一致するようにスロットル開度を制御することを特徴とする内燃機関の制御方法。Control of an internal combustion engine in which a fuel injection valve for injecting fuel is installed in the vicinity of an intake port of each cylinder of the internal combustion engine, and a required torque requested by a driver is determined and operation of the internal combustion engine is controlled based on the required torque In the method
Based on the required torque, the reference model of the target cylinder charge air amount is calculated, the target cylinder inflow fuel amount is calculated based on the reference model and the target air-fuel ratio, and the fuel transportation delay due to the fuel adhering to the intake system wall surface, etc. The fuel injection amount to be injected from the fuel injection valve is determined so that the actual in-cylinder inflow fuel amount coincides with the target in-cylinder inflow fuel amount, and at least the norm of the target in-cylinder charged air amount A command value of the throttle opening is calculated based on the model and the internal combustion engine rotational speed, and a delay time (Z −) from the fuel injection amount determination timing to the intake valve closing timing at which the cylinder charge air amount and the cylinder inflow fuel amount are determined. L) and slow-is time (Z -L) response delay time of the throttle valve is shorter than the (Z -m) and the time shift amount of (Z - (Lm)) by a phase command value of the throttle opening The fuel injection amount decision The target in-cylinder obtained by delaying the phase of the reference model by the delay time (Z -L ) from the reference model to the intake valve closing timing by driving the throttle valve with a delay from a fixed timing A control method for an internal combustion engine, wherein the throttle opening is controlled so as to coincide with the amount of charged air.
JP2000055919A 2000-02-28 2000-02-28 Control device and control method for internal combustion engine Expired - Fee Related JP4378665B2 (en)

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JP4893553B2 (en) 2007-09-25 2012-03-07 トヨタ自動車株式会社 Control device for internal combustion engine
JP5195651B2 (en) * 2009-06-03 2013-05-08 トヨタ自動車株式会社 Control device for internal combustion engine
JP5229118B2 (en) * 2009-06-09 2013-07-03 トヨタ自動車株式会社 Internal combustion engine torque control device
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