JP2007332944A - Fuel injection control device of internal combustion engine - Google Patents

Fuel injection control device of internal combustion engine Download PDF

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JP2007332944A
JP2007332944A JP2006169272A JP2006169272A JP2007332944A JP 2007332944 A JP2007332944 A JP 2007332944A JP 2006169272 A JP2006169272 A JP 2006169272A JP 2006169272 A JP2006169272 A JP 2006169272A JP 2007332944 A JP2007332944 A JP 2007332944A
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injection amount
fuel
injection
intake
calculated
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Futoshi Yoshimura
太 吉村
Kenichi Sato
健一 佐藤
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Nissan Motor Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To enhance a correlation with the cylinder suction air volume, by making both compatible in promoting vaporization of fuel and improving transitional responsiveness. <P>SOLUTION: The newest request injection quantity is calculated in an exhaust stroke of respective cylinders, and a part of this newest request injection quantity is injected as a first time injection quantity. Afterwards, the newest request injection quantity is calculated in the same piston position as the intake valve closing timing after the bottom dead center before the bottom dead center of an intake stroke of the respective cylinders, and a second time injection quantity is calculated by subtracting the first time injection quantity injected in an exhaust stroke from this newest request injection quantity. The fuel of this second time injection quantity is injected so as to finish fuel injection up to the intake valve closing timing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、吸気通路に各気筒毎に燃料噴射弁を備える内燃機関の燃料噴射制御装置に関する。   The present invention relates to a fuel injection control device for an internal combustion engine provided with a fuel injection valve for each cylinder in an intake passage.

特許文献１では、吸気通路に各気筒毎に燃料噴射弁を備える内燃機関において、燃料噴射を２回に分割し、１回目の燃料噴射は、そのときの要求噴射量から所定量を減じた先行噴射量の燃料を噴射し、２回目の燃料噴射では、そのときの要求噴射量から先行噴射量を減じた後行噴射量の燃料を噴射するようにして、先行噴射による燃料の気化の促進と、最新の要求噴射量に基づくことによる過渡応答性の向上とを両立させている。
特開平４−２９２５４３号公報 In Patent Document 1, in an internal combustion engine provided with a fuel injection valve for each cylinder in an intake passage, fuel injection is divided into two times, and the first fuel injection is preceded by subtracting a predetermined amount from the required injection amount at that time. Injecting the fuel of the injection amount, and in the second fuel injection, the fuel injection of the fuel by the preceding injection is promoted by injecting the fuel of the subsequent injection amount obtained by subtracting the preceding injection amount from the required injection amount at that time. In addition, the transient response is improved by being based on the latest required injection amount.
JP-A-4-292543

しかしながら、特許文献１に記載の技術では、２回目の燃料噴射を排気行程若しくは吸気行程にて行うとしているが、単にその燃料噴射時期に先立って噴射量の演算時期を設定するだけでは、実際にシリンダに吸入される空気量に対応するような噴射量を算出することができず、シリンダ吸入空気量に合わせて分割噴射を行うことができないという問題点があった。   However, in the technique described in Patent Document 1, the second fuel injection is performed in the exhaust stroke or the intake stroke. However, if the injection amount calculation timing is simply set prior to the fuel injection timing, There is a problem that it is impossible to calculate the injection amount corresponding to the amount of air sucked into the cylinder, and it is impossible to perform divided injection in accordance with the cylinder intake air amount.

本発明は、このような従来の問題点に鑑み、燃料の気化促進と、過渡応答性の向上との両立を図り、更にシリンダ吸入空気量との相関を高めることを目的とする。   SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and aims to achieve both the acceleration of fuel vaporization and the improvement of transient response and further increase the correlation with the amount of cylinder intake air.

このため、請求項１に係る発明では、各気筒の吸気行程前に最新の要求噴射量を算出し、この最新の要求噴射量の一部を１回目の噴射量として算出し、吸気行程前にこの１回目の噴射量の燃料を噴射させる。その後、各気筒の吸気行程の吸気下死点前であって、吸気下死点後の吸気弁閉時期と同じピストン位置にて、最新の要求噴射量を算出し、この最新の要求噴射量から吸気行程前に噴射した１回目の噴射量を減算して、２回目の噴射量を算出する。そして、吸気弁閉時期までに燃料噴射を終了するように、この２回目の噴射量の燃料を噴射させる。   For this reason, in the invention according to claim 1, the latest required injection amount is calculated before the intake stroke of each cylinder, a part of the latest required injection amount is calculated as the first injection amount, and before the intake stroke, This first injection amount of fuel is injected. After that, calculate the latest required injection amount at the same piston position as the intake valve closing timing after the intake bottom dead center before the intake bottom dead center of the intake stroke of each cylinder, and from this latest required injection amount A second injection amount is calculated by subtracting the first injection amount injected before the intake stroke. Then, the second injection amount of fuel is injected so that the fuel injection is completed by the intake valve closing timing.

また、請求項２に係る発明では、各気筒の吸気行程前に最新の要求噴射量を算出し、この最新の要求噴射量の一部を１回目の噴射量として算出し、吸気行程前にこの１回目の噴射量の燃料を噴射させる。その後、各気筒の吸気行程にて一定時間間隔で最新の要求噴射量を算出し、最新の要求噴射量を算出する毎に、最新の要求噴射量から吸気行程前に噴射した１回目の噴射量を減算して、２回目の噴射量を算出する。そして、吸気弁閉時期までに燃料噴射を終了するように、吸気弁閉時期までに燃料噴射を終了可能な範囲で、最も遅い時期に算出した２回目の噴射量の燃料を噴射させる。   In the invention according to claim 2, the latest required injection amount is calculated before the intake stroke of each cylinder, a part of the latest required injection amount is calculated as the first injection amount, and before the intake stroke, The first injection amount of fuel is injected. After that, the latest required injection amount is calculated at regular time intervals in the intake stroke of each cylinder, and every time the latest required injection amount is calculated, the first injection amount injected before the intake stroke from the latest required injection amount Is subtracted to calculate the second injection amount. Then, the fuel of the second injection amount calculated at the latest timing is injected within a range in which the fuel injection can be completed by the intake valve closing timing so that the fuel injection is completed by the intake valve closing timing.

請求項１に係る発明によれば、２回目の噴射量の演算は、吸気弁閉時期と同じピストン位置にて行うため、吸気弁閉時期のシリンダ吸入空気量と同等の空気量にて、噴射量の演算を行うことができ、噴射量演算時の空気量と実際のシリンダ吸入空気量との誤差を大幅に低減できる。
請求項２に係る発明によれば、２回目の噴射量の演算時期を可能な限り吸気弁閉時期に近づけることができ、吸気弁閉時期のシリンダ吸入空気量に近い空気量にて、噴射量の演算を行うことができ、噴射量演算時の空気量と実際のシリンダ吸入空気量との誤差を大幅に低減できる。 According to the first aspect of the invention, since the second injection amount calculation is performed at the same piston position as the intake valve closing timing, the injection amount is equal to the cylinder intake air amount at the intake valve closing timing. The amount can be calculated, and the error between the air amount during the injection amount calculation and the actual cylinder intake air amount can be greatly reduced.
According to the second aspect of the present invention, the calculation timing of the second injection amount can be as close as possible to the intake valve closing timing, and the injection amount is equal to the cylinder intake air amount at the intake valve closing timing. Thus, the error between the air amount at the time of calculating the injection amount and the actual cylinder intake air amount can be greatly reduced.

以下に本発明の実施の形態を図面に基づいて説明する。
図１は本発明の一実施形態を示す内燃機関（エンジン）のシステム図である。
エンジン１の各気筒のピストン２により画成される燃焼室３には、点火プラグ４を囲むように、吸気弁５及び排気弁６を備えている。吸気弁５及び排気弁６は、可変動弁装置７、８により開閉時期を調整可能である。 Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a system diagram of an internal combustion engine (engine) showing an embodiment of the present invention.
The combustion chamber 3 defined by the piston 2 of each cylinder of the engine 1 is provided with an intake valve 5 and an exhaust valve 6 so as to surround the spark plug 4. The intake valve 5 and the exhaust valve 6 can be adjusted in opening / closing timing by the variable valve gears 7 and 8.

吸気通路９には、吸気マニホールドの上流側に、モータ駆動の電制スロットル弁１０が設けられている。吸気通路９にはまた、吸気マニホールドの各ブランチ部（シリンダヘッド側の吸気ポートに臨む位置）に、各気筒毎に、電磁式の燃料噴射弁１１が設けられており、吸気弁５の弁傘部に向けて燃料を噴射することができる。
排気通路１２には、排気浄化触媒１３が設けられている。 In the intake passage 9, a motor-driven electric throttle valve 10 is provided on the upstream side of the intake manifold. The intake passage 9 is also provided with an electromagnetic fuel injection valve 11 for each cylinder at each branch portion (position facing the intake port on the cylinder head side) of the intake manifold. The fuel can be injected toward the part.
An exhaust purification catalyst 13 is provided in the exhaust passage 12.

ここにおいて、可変動弁装置７、８、電制スロットル弁１０、燃料噴射弁１１及び点火プラグ４の作動は、エンジンコントロールユニット（以下ＥＣＵという）２０により制御され、このＥＣＵ２０には、エンジン回転に同期してクランク角信号を出力しこれによりクランク角位置と共にエンジン回転数Ｎｅを検出可能なクランク角センサ２１、アクセルペダルの操作量（アクセル開度）ＡＰＯを検出するアクセル開度センサ２２、吸気通路９の電制スロットル弁１０上流にて吸入空気量Ｑａを検出するエアフローメータ２３、エンジン冷却水温Ｔｗを検出する水温センサ２４などから、信号が入力されている。   Here, the operations of the variable valve gears 7 and 8, the electric throttle valve 10, the fuel injection valve 11 and the spark plug 4 are controlled by an engine control unit (hereinafter referred to as ECU) 20, and the ECU 20 controls the engine rotation. A crank angle sensor 21 that can output a crank angle signal in synchronization and detect the engine speed Ne together with the crank angle position, an accelerator opening sensor 22 that detects an accelerator pedal operation amount (accelerator opening) APO, an intake passage Signals are input from an air flow meter 23 for detecting the intake air amount Qa upstream of the electronic throttle valve 10 and a water temperature sensor 24 for detecting the engine coolant temperature Tw.

燃料噴射弁１１による燃料噴射量の制御は、吸入空気量Ｑａとエンジン回転数Ｎｅとから基本噴射量Ｔｐ＝Ｋ・Ｑａ／Ｎｅ（Ｋは定数）を算出し、これを各種補正係数ＣＯＥＦで補正して、最終的な噴射量（要求噴射量）Ｔｉ＝Ｔｐ・ＣＯＥＦを算出し、制御する。尚、燃料噴射弁１１は所定圧力に調圧された燃料を噴射するので、燃料噴射弁１１の開時間（噴射時間）より噴射量を制御できることから、噴射量は噴射時間（噴射パルス幅）として算出する。   The control of the fuel injection amount by the fuel injection valve 11 is performed by calculating the basic injection amount Tp = K · Qa / Ne (K is a constant) from the intake air amount Qa and the engine speed Ne, and correcting this with various correction coefficients COEF. Then, the final injection amount (required injection amount) Ti = Tp · COEF is calculated and controlled. In addition, since the fuel injection valve 11 injects the fuel adjusted to a predetermined pressure, the injection amount can be controlled from the open time (injection time) of the fuel injection valve 11, so the injection amount is set as the injection time (injection pulse width). calculate.

ここで、通常は、要求噴射量Ｔｉの燃料を排気行程などにおいて１回で噴射するが、本発明では、特に始動時を含む過渡時において、燃料噴射を２回に分割することで、気化の促進と、過渡応答性の向上とを両立させる。
かかる分割噴射の制御について、フローチャートにより説明する。
図２は第１実施形態での分割噴射の制御のフローチャートである。 Here, normally, the fuel of the required injection amount Ti is injected once in the exhaust stroke or the like. However, in the present invention, the fuel injection is divided into two times, especially during the transition including the start-up. Both promotion and improvement of transient response are achieved.
The control of the divided injection will be described with reference to a flowchart.
FIG. 2 is a flowchart of split injection control in the first embodiment.

Ｓ１では、排気行程の所定の噴射量演算時期か否かを判定し、ＹＥＳの場合に、Ｓ２〜Ｓ４の処理を実行する。
Ｓ２では、排気行程の所定の噴射量演算時期（予め定めた時期）において、現在の運転条件に基づく、最新の要求噴射量Ｔｉを算出する。具体的には、現時点の吸入空気量Ｑａとエンジン回転数Ｎｅとに基づいて、要求噴射量Ｔｉ＝Ｋ・Ｑａ／Ｎｅ・ＣＯＥＦ（Ｋは定数、ＣＯＥＦは各種補正係数）を算出する。 In S1, it is determined whether or not it is a predetermined injection amount calculation time for the exhaust stroke. If YES, the processes of S2 to S4 are executed.
In S2, the latest required injection amount Ti based on the current operating conditions is calculated at a predetermined injection amount calculation time (predetermined time) in the exhaust stroke. Specifically, the required injection amount Ti = K · Qa / Ne · COEF (K is a constant, and COEF is various correction coefficients) is calculated based on the current intake air amount Qa and the engine speed Ne.

Ｓ３では、Ｓ２で算出した要求噴射量Ｔｉの一部（大部分で、例えば８０％程度）を１回目の噴射量Ｔｉ１として算出する。具体的には、最新の要求噴射量Ｔｉから所定量ＣＴｉを減算して、１回目の噴射量Ｔｉ１＝Ｔｉ−ＣＴｉを算出する。
Ｓ４では、排気行程にて、上記１回目の噴射量Ｔｉ１の燃料を噴射させる。
排気行程にて噴射された燃料は、閉弁中の吸気弁の傘裏に衝突し、熱を受けることで、吸気弁が開弁するまでの間に、気化が促進され、吸気弁の開弁により燃焼室内に吸入される。 In S3, a part of the required injection amount Ti calculated in S2 (mostly, for example, about 80%) is calculated as the first injection amount Ti1. Specifically, the first injection amount Ti1 = Ti−CTi is calculated by subtracting the predetermined amount CTi from the latest required injection amount Ti.
In S4, the fuel of the first injection amount Ti1 is injected in the exhaust stroke.
The fuel injected in the exhaust stroke collides with the back of the intake valve being closed and receives heat, so that vaporization is accelerated before the intake valve opens, and the intake valve opens. Is sucked into the combustion chamber.

Ｓ５では、吸気行程の所定の噴射量演算時期、具体的には、図４（ａ）又は（ｂ）に示すように、吸気下死点前であって、吸気下死点後の吸気弁閉時期（ＩＶＣ）と同じピストン位置の時期か否かを判定し、ＹＥＳの場合に、Ｓ６〜Ｓ８の処理を実行する。
Ｓ６では、吸気行程の所定の噴射量演算時期において、現在の運転条件に基づく、最新の要求噴射量Ｔｉを算出する。具体的には、現時点の吸入空気量Ｑａとエンジン回転数Ｎｅとに基づいて、要求噴射量Ｔｉ＝Ｋ・Ｑａ／Ｎｅ・ＣＯＥＦ（Ｋは定数、ＣＯＥＦは各種補正係数）を算出する。 In S5, the predetermined injection amount calculation timing of the intake stroke, specifically, as shown in FIG. 4 (a) or (b), the intake valve is closed before the intake bottom dead center and after the intake bottom dead center. It is determined whether or not it is the same piston position time as the time (IVC). If YES, the processes of S6 to S8 are executed.
In S6, the latest required injection amount Ti based on the current operating conditions is calculated at a predetermined injection amount calculation timing in the intake stroke. Specifically, the required injection amount Ti = K · Qa / Ne · COEF (K is a constant, and COEF is various correction coefficients) is calculated based on the current intake air amount Qa and the engine speed Ne.

Ｓ７では、Ｓ６で算出した最新の要求噴射量Ｔｉから、排気行程にて噴射した１回目の噴射量Ｔｉ１を減算して、２回目の噴射量Ｔｉ２＝Ｔｉ−Ｔｉ１を算出する。
Ｓ８では、吸気弁閉時期ＩＶＣまでに燃料噴射を終了するように、上記２回目の噴射量Ｔｉ２の燃料を噴射させる。
尚、Ｓ１〜Ｓ３の部分が第１の噴射量算出手段に相当し、Ｓ４の部分が第１の燃料噴射手段に相当し、Ｓ５〜Ｓ７の部分が第２の噴射量算出手段に相当し、Ｓ８の部分が第２の燃料噴射手段に相当する。 In S7, the second injection amount Ti2 = Ti−Ti1 is calculated by subtracting the first injection amount Ti1 injected in the exhaust stroke from the latest required injection amount Ti calculated in S6.
In S8, the fuel of the second injection amount Ti2 is injected so that the fuel injection is completed by the intake valve closing timing IVC.
In addition, the part of S1-S3 is equivalent to a 1st injection amount calculation means, the part of S4 is equivalent to a 1st fuel injection means, the part of S5-S7 is equivalent to a 2nd injection amount calculation means, S8 corresponds to the second fuel injection means.

本フローでは、図３に示すように、各気筒の排気行程にて、そのときの吸入空気量Ｑａ及びエンジン回転数Ｎｅに基づいて、最新の要求噴射量Ｔｉを算出し、この最新の要求噴射量の一部（大部分）を１回目の噴射量Ｔｉ１として算出し、排気行程にてこの１回目の噴射量の燃料を噴射させることにより、吸気弁開弁までに燃料の気化を促進して、燃焼性の改善を図る。また、吸気行程で燃料を噴射すると均質度の低下による燃焼の悪化や、燃料の排気側への吹き抜けによるエンジンアウトＨＣの悪化を生じるが、必要な燃料の大部分を排気行程で噴射することにより、このような問題も回避できる。   In this flow, as shown in FIG. 3, in the exhaust stroke of each cylinder, the latest required injection amount Ti is calculated based on the intake air amount Qa and the engine speed Ne at that time, and this latest required injection A part (most part) of the amount is calculated as the first injection amount Ti1, and the fuel of the first injection amount is injected in the exhaust stroke to promote the vaporization of the fuel until the intake valve opens. , To improve combustibility. In addition, when fuel is injected in the intake stroke, deterioration of combustion due to a decrease in homogeneity and deterioration of engine-out HC due to blow-out of fuel to the exhaust side occur, but by injecting most of the necessary fuel in the exhaust stroke, Such a problem can also be avoided.

その一方、各気筒の吸気行程の吸気下死点前であって、吸気下死点後の吸気弁閉時期（ＩＶＣ）と同じピストン位置にて、そのときの吸入空気量Ｑａ及びエンジン回転数Ｎｅに基づいて、最新の要求噴射量Ｔｉを算出し、この最新の要求噴射量Ｔｉから１回目の噴射量Ｔｉ１を減算して、２回目の噴射量Ｔｉ２を算出し、吸気弁閉時期ＩＶＣまでに燃料噴射を終了するように、この２回目の噴射量Ｔｉ２の燃料を噴射させる。   On the other hand, at the same piston position as the intake valve closing timing (IVC) after the intake bottom dead center before the intake bottom dead center of the intake stroke of each cylinder, the intake air amount Qa and the engine speed Ne at that time The latest required injection amount Ti is calculated, the first injection amount Ti1 is subtracted from the latest required injection amount Ti, the second injection amount Ti2 is calculated, and the intake valve closing timing IVC is reached. The fuel of the second injection amount Ti2 is injected so as to end the fuel injection.

ここで、１回目に算出した要求噴射量をＴｉold 、２回目に算出した要求噴射量をＴｉnew とすると、１回目の噴射量Ｔｉ１に対し、２回目の噴射量Ｔｉ２は、Ｔｉ２＝Ｔｉnew −Ｔｉ１であるので、１回目と２回目の噴射量の合計値は、Ｔｉ１＋Ｔｉ２＝Ｔｉ１＋（Ｔｉnew −Ｔｉ１）＝Ｔｉnew となり、２回目に算出した最新の要求噴射量Ｔｉnew と等しくなることから、過渡応答性を向上させることができる。   Here, if the required injection amount calculated for the first time is Tiold, and the required injection amount calculated for the second time is Tinew, the second injection amount Ti2 is Ti2 = Tinew−Ti1 with respect to the first injection amount Ti1. Therefore, the total value of the first and second injection amounts is Ti1 + Ti2 = Ti1 + (Tinew−Ti1) = Tinew, which is equal to the latest required injection amount Tinew calculated the second time, thus improving the transient response. Can be made.

また、２回目の噴射量の演算は、図４（ａ）又は（ｂ）に示すように、吸気弁閉時期ＩＶＣと同じピストン位置にて行うため、吸気弁閉時期ＩＶＣのシリンダ吸入空気量と同等の空気量にて、噴射量の演算を行うことができ、噴射量演算時の空気量と実際のシリンダ吸入空気量との誤差を大幅に低減できる。これにより、噴射量の制御精度を向上させ、始動時を含む過渡時の排気性能などを大幅に向上できる。   Further, as shown in FIG. 4 (a) or (b), the calculation of the second injection amount is performed at the same piston position as the intake valve closing timing IVC, and therefore the cylinder intake air amount at the intake valve closing timing IVC and The injection amount can be calculated with the same air amount, and the error between the air amount during the injection amount calculation and the actual cylinder intake air amount can be greatly reduced. Thereby, the control accuracy of the injection amount can be improved, and the exhaust performance at the time of transition including the start time can be greatly improved.

尚、本実施形態は、他気筒の吸気による自気筒の圧力変化が無視できる場合、具体的には、図４（ａ）のように、各気筒の吸気行程が重ならないバルブタイミングの場合や、図４（ｂ）のように、吸気弁閉時期ＩＶＣが下死点に近く、他気筒の吸気体積変化が小さく無視できる場合に、特に有効である。
また、本実施形態によれば、最新の要求噴射量Ｔｉの一部（大部分）を１回目の噴射量Ｔｉ１として算出する際、最新の要求噴射量Ｔｉから所定量ＣＴｉを減算して、１回目の噴射量Ｔｉ１＝Ｔｉ−ＣＴｉを算出するので、容易に算出できる。 In the present embodiment, when the pressure change of the own cylinder due to the intake of the other cylinders can be ignored, specifically, as shown in FIG. 4A, in the case of the valve timing where the intake strokes of the respective cylinders do not overlap, As shown in FIG. 4B, this is particularly effective when the intake valve closing timing IVC is close to bottom dead center and the intake volume change of other cylinders is small and can be ignored.
Further, according to the present embodiment, when a part (most part) of the latest required injection amount Ti is calculated as the first injection amount Ti1, the predetermined amount CTi is subtracted from the latest required injection amount Ti. Since the second injection amount Ti1 = Ti-CTi is calculated, it can be easily calculated.

また、本実施形態によれば、各気筒の排気行程にて、１回目の噴射量を算出し、噴射させることにより、必要かつ十分な気化性能を得ることができる。
尚、バルブタイミングによっては、吸気弁閉時期ＩＶＣまでに２回目の燃料噴射を終了できないことが考えられるが、その場合は、可変動弁装置を用いて、バルブタイミングを適宜変更すればよい。 Further, according to the present embodiment, necessary and sufficient vaporization performance can be obtained by calculating and injecting the first injection amount in the exhaust stroke of each cylinder.
Note that, depending on the valve timing, it is conceivable that the second fuel injection cannot be completed by the intake valve closing timing IVC. In this case, the valve timing may be appropriately changed using a variable valve operating device.

図５は第２実施形態のフローチャートを示している。
Ｓ１１〜Ｓ１４での排気行程での１回目の噴射量演算、噴射制御については、第１実施形態（図２）のＳ１〜Ｓ４と同じであり、説明を省略する。
Ｓ１５では、吸気行程の所定の噴射量演算時期（予め定めた演算開始時期）か否かを判定し、ＹＥＳの場合に、Ｓ１６以降の処理を実行する。 FIG. 5 shows a flowchart of the second embodiment.
The first injection amount calculation and the injection control in the exhaust stroke in S11 to S14 are the same as S1 to S4 in the first embodiment (FIG. 2), and the description is omitted.
In S15, it is determined whether or not it is a predetermined injection amount calculation time (predetermined calculation start time) of the intake stroke. If YES, the processing after S16 is executed.

Ｓ１６では、現在の運転条件に基づく、最新の要求噴射量Ｔｉを算出する。具体的には、現時点の吸入空気量Ｑａとエンジン回転数Ｎｅとに基づいて、要求噴射量Ｔｉ＝Ｋ・Ｑａ／Ｎｅ・ＣＯＥＦ（Ｋは定数、ＣＯＥＦは各種補正係数）を算出する。
Ｓ１７では、Ｓ１６で算出した最新の要求噴射量Ｔｉから、排気行程にて噴射した１回目の噴射量Ｔｉ１を減算して、２回目の噴射量Ｔｉ２＝Ｔｉ−Ｔｉ１を算出する。 In S16, the latest required injection amount Ti based on the current operating conditions is calculated. Specifically, the required injection amount Ti = K · Qa / Ne · COEF (K is a constant, and COEF is various correction coefficients) is calculated based on the current intake air amount Qa and the engine speed Ne.
In S17, the second injection amount Ti2 = Ti−Ti1 is calculated by subtracting the first injection amount Ti1 injected in the exhaust stroke from the latest required injection amount Ti calculated in S16.

Ｓ１８では、現在のエンジン回転数Ｎｅと、吸気弁閉時期ＩＶＣ（クランク角度）より、吸気弁閉時期ＩＶＣまでの時間ＴＩＶＣを算出する。
Ｓ１９では、吸気弁閉時期ＩＶＣまでの時間ＴＩＶＣから、２回目の噴射量（噴射時間）Ｔｉ２を減算して、余裕時間（ＴＩＶＣ−Ｔｉ２）を求め、これが所定値未満か否かを判定する。 In S18, a time TIVC to the intake valve closing timing IVC is calculated from the current engine speed Ne and the intake valve closing timing IVC (crank angle).
In S19, the second injection amount (injection time) Ti2 is subtracted from the time TIVC until the intake valve closing timing IVC to obtain a margin time (TIVC-Ti2), and it is determined whether this is less than a predetermined value.

ＴＩＶＣ−Ｔｉ２≧所定値であれば、まだ十分に、吸気弁閉時期ＩＶＣまでに２回目の燃料噴射を終了する余裕があると判断して、Ｓ１６へ戻り、最新の要求噴射量Ｔｉの演算（Ｓ１６）と、２回目の噴射量Ｔｉ２の演算（Ｓ１７）と、吸気弁閉時期ＩＶＣまでの時間ＴＩＶＣの算出（Ｓ１８）と、余裕時間の判定（Ｓ１９）とを、一定時間間隔で繰り返す。   If TIVC−Ti2 ≧ predetermined value, it is determined that there is still enough room to finish the second fuel injection by the intake valve closing timing IVC, and the process returns to S16 to calculate the latest required injection amount Ti ( S16), the calculation of the second injection amount Ti2 (S17), the calculation of the time TIVC to the intake valve closing timing IVC (S18), and the allowance time determination (S19) are repeated at regular time intervals.

この結果、Ｓ１９での判定で、ＴＩＶＣ−Ｔｉ２＜所定値となると、吸気弁閉時期ＩＶＣまでに燃料噴射を終了可能な範囲で、最も遅い時期であると判断し、Ｓ２０へ進む。
Ｓ２０では、吸気弁閉時期ＩＶＣまでに燃料噴射を終了するように、吸気弁閉時期ＩＶＣまでに燃料噴射を終了可能な範囲で、最も遅い時期に算出した、上記２回目の噴射量Ｔｉ２の燃料を噴射させる。 As a result, if TIVC-Ti2 <predetermined value is determined in S19, it is determined that it is the latest time within the range in which fuel injection can be completed by the intake valve closing timing IVC, and the process proceeds to S20.
In S20, the fuel of the second injection amount Ti2 calculated at the latest time within the range in which the fuel injection can be completed by the intake valve closing timing IVC so that the fuel injection is completed by the intake valve closing timing IVC. To spray.

尚、Ｓ１１〜Ｓ１３の部分が第１の噴射量算出手段に相当し、Ｓ１４の部分が第１の燃料噴射手段に相当し、Ｓ１５〜Ｓ１７の部分が第２の噴射量算出手段に相当し、Ｓ１８〜Ｓ２０の部分が第２の燃料噴射手段に相当する。
本フローでは、図６に示すように、各気筒の排気行程にて、そのときの吸入空気量Ｑａ及びエンジン回転数Ｎｅに基づいて、最新の要求噴射量Ｔｉを算出し、この最新の要求噴射量の一部（大部分）を１回目の噴射量Ｔｉ１として算出し、排気行程にてこの１回目の噴射量の燃料を噴射させることにより、吸気弁開弁までに燃料の気化を促進して、燃焼性の改善などを図る。この点は第１実施形態と同じ。 The portions S11 to S13 correspond to the first injection amount calculation means, the portion S14 corresponds to the first fuel injection means, the portions S15 to S17 correspond to the second injection amount calculation means, S18 to S20 correspond to the second fuel injection means.
In this flow, as shown in FIG. 6, in the exhaust stroke of each cylinder, the latest required injection amount Ti is calculated based on the intake air amount Qa and the engine speed Ne at that time, and this latest required injection A part (most part) of the amount is calculated as the first injection amount Ti1, and the fuel of the first injection amount is injected in the exhaust stroke to promote the vaporization of the fuel until the intake valve opens. , Improve combustibility. This is the same as in the first embodiment.

その一方、各気筒の吸気行程にて一定時間間隔で、最新の吸入空気量Ｑａ及びエンジン回転数Ｎｅに基づいて、最新の要求噴射量Ｔｉを算出し、最新の要求噴射量Ｔｉを算出する毎に、最新の要求噴射量Ｔｉから１回目の噴射量Ｔｉ１を減算して、２回目の噴射量Ｔｉ２を算出し、吸気弁閉時期ＩＶＣまでに燃料噴射を終了するように、吸気弁閉時期ＩＶＣまでに燃料噴射を終了可能な範囲で、最も遅い時期に算出した２回目の噴射量Ｔｉ２の燃料を噴射させる。   On the other hand, every time the latest required injection amount Ti is calculated based on the latest intake air amount Qa and the engine speed Ne at regular time intervals in the intake stroke of each cylinder. Then, the first injection amount Ti1 is subtracted from the latest required injection amount Ti to calculate the second injection amount Ti2, and the fuel injection is terminated by the intake valve closing timing IVC. The fuel of the second injection amount Ti2 calculated at the latest time is injected within a range where the fuel injection can be completed by the time.

従って、１回目と２回目の噴射量の合計値は、第１実施形態と同様、Ｔｉ１＋Ｔｉ２＝Ｔｉ１＋（Ｔｉnew −Ｔｉ１）＝Ｔｉnew となり、２回目の噴射量として最後に演算した時に用いた最新の要求噴射量Ｔｉnew と等しくなることから、過渡応答性を向上させることができる。
また、２回目の噴射量の演算時期を、図７に示すように、可能な限り吸気弁閉時期ＩＶＣに近づけることができ、吸気弁閉時期ＩＶＣのシリンダ吸入空気量に近い空気量にて、噴射量の演算を行うことができ、噴射量演算時の空気量と実際のシリンダ吸入空気量との誤差を大幅に低減できる。これにより、噴射量の制御精度を向上させ、始動時を含む過渡時の排気性能などを大幅に向上できる。 Accordingly, the total value of the first and second injection amounts is Ti1 + Ti2 = Ti1 + (Tinew−Ti1) = Tinew as in the first embodiment, and the latest request used when the last injection amount is calculated last. Since it becomes equal to the injection amount Tinew, the transient response can be improved.
Further, as shown in FIG. 7, the calculation timing of the second injection amount can be as close as possible to the intake valve closing timing IVC, and with an air amount close to the cylinder intake air amount at the intake valve closing timing IVC, The injection amount can be calculated, and the error between the air amount at the time of calculating the injection amount and the actual cylinder intake air amount can be greatly reduced. Thereby, the control accuracy of the injection amount can be improved, and the exhaust performance at the time of transition including the start time can be greatly improved.

尚、本実施形態は、図７のように、他気筒での吸気行程が自気筒の吸気圧力に影響があるバルブタイミングの場合（他気筒の吸気により自気筒の圧力が変化する場合）に、特に有効である。
また、本実施形態によれば、吸気行程にて２回目の噴射量Ｔｉ２が算出される毎に、吸気弁閉時期ＩＶＣまでの時間ＴＩＶＣと２回目の噴射量の燃料噴射に要する時間Ｔｉ２との差を算出し、この差が所定値未満となっているときに、２回目の噴射量の燃料を噴射させる制御構成とすることで、簡単な制御ロジックで実施できる。 In this embodiment, as shown in FIG. 7, when the intake stroke in the other cylinder has a valve timing that affects the intake pressure of the own cylinder (when the pressure of the own cylinder changes due to the intake of the other cylinder), It is particularly effective.
Further, according to the present embodiment, every time the second injection amount Ti2 is calculated in the intake stroke, the time TIVC until the intake valve closing timing IVC and the time Ti2 required for fuel injection of the second injection amount are calculated. By calculating the difference, and when the difference is less than a predetermined value, a control configuration in which the fuel of the second injection amount is injected can be implemented with simple control logic.

本発明の一実施形態を示すエンジンのシステム図Engine system diagram showing an embodiment of the present invention 第１実施形態での分割噴射の制御のフローチャートFlowchart of split injection control in the first embodiment 第１実施形態でのタイミングチャートTiming chart in the first embodiment 第１実施形態での吸気弁開閉時期と関連を示す図The figure which shows the relationship with the intake valve opening and closing timing in 1st Embodiment 第２実施形態での分割噴射の制御のフローチャートFlowchart of split injection control in the second embodiment 第２実施形態でのタイミングチャートTiming chart in the second embodiment 第２実施形態での吸気弁開閉時期との関連を示す図The figure which shows the relationship with the intake valve opening and closing timing in 2nd Embodiment

符号の説明Explanation of symbols

１ エンジン
２ ピストン
３ 燃焼室
４ 点火プラグ
５ 吸気弁
６ 排気弁
７、８ 可変動弁装置
９ 吸気通路
１０ 電制スロットル弁
１１ 燃料噴射弁
１２ 排気通路
１３ 排気浄化触媒
２０ ＥＣＵ
２１ クランク角センサ
２２ アクセル開度センサ
２３ エアフローメータ
２４ 水温センサ DESCRIPTION OF SYMBOLS 1 Engine 2 Piston 3 Combustion chamber 4 Spark plug 5 Intake valve 6 Exhaust valve 7, 8 Variable valve gear 9 Intake passage 10 Electric throttle valve 11 Fuel injection valve 12 Exhaust passage 13 Exhaust purification catalyst 20 ECU
21 Crank angle sensor 22 Accelerator opening sensor 23 Air flow meter 24 Water temperature sensor

Claims (5)

吸気通路に各気筒毎に燃料噴射弁を備える内燃機関において、
各気筒の吸気行程前に最新の要求噴射量を算出し、この最新の要求噴射量の一部を１回目の噴射量として算出する第１の噴射量算出手段と、
吸気行程前にこの１回目の噴射量の燃料を噴射させる第１の燃料噴射手段と、
各気筒の吸気行程の吸気下死点前であって、吸気下死点後の吸気弁閉時期と同じピストン位置にて、最新の要求噴射量を算出し、この最新の要求噴射量から吸気行程前に噴射した１回目の噴射量を減算して、２回目の噴射量を算出する第２の噴射量算出手段と、
吸気弁閉時期までに燃料噴射を終了するように、この２回目の噴射量の燃料を噴射させる第２の燃料噴射手段と、
を備えることを特徴とする内燃機関の燃料噴射制御装置。 In an internal combustion engine provided with a fuel injection valve for each cylinder in the intake passage,
A first injection amount calculating means for calculating the latest required injection amount before the intake stroke of each cylinder and calculating a part of the latest required injection amount as a first injection amount;
First fuel injection means for injecting fuel of the first injection amount before the intake stroke;
The latest required injection amount is calculated at the same piston position as the intake valve closing timing after the intake bottom dead center before the intake bottom dead center of the intake stroke of each cylinder, and the intake stroke is calculated from this latest required injection amount. A second injection amount calculating means for subtracting the first injection amount injected before and calculating a second injection amount;
A second fuel injection means for injecting fuel of the second injection amount so as to finish fuel injection by the intake valve closing timing;
A fuel injection control device for an internal combustion engine, comprising: 吸気通路に各気筒毎に燃料噴射弁を備える内燃機関において、
各気筒の吸気行程前に最新の要求噴射量を算出し、この最新の要求噴射量の一部を１回目の噴射量として算出する第１の噴射量算出手段と、
吸気行程前にこの１回目の噴射量の燃料を噴射させる第１の燃料噴射手段と、
各気筒の吸気行程にて一定時間間隔で最新の要求噴射量を算出し、最新の要求噴射量を算出する毎に、最新の要求噴射量から吸気行程前に噴射した１回目の噴射量を減算して、２回目の噴射量を算出する第２の噴射量算出手段と、
吸気弁閉時期までに燃料噴射を終了するように、吸気弁閉時期までに燃料噴射を終了可能な範囲で、最も遅い時期に算出した２回目の噴射量の燃料を噴射させる第２の燃料噴射手段と、
を備えることを特徴とする内燃機関の燃料噴射制御装置。 In an internal combustion engine provided with a fuel injection valve for each cylinder in the intake passage,
A first injection amount calculating means for calculating the latest required injection amount before the intake stroke of each cylinder and calculating a part of the latest required injection amount as a first injection amount;
First fuel injection means for injecting fuel of the first injection amount before the intake stroke;
The latest required injection amount is calculated at regular time intervals in the intake stroke of each cylinder, and every time the latest required injection amount is calculated, the first injection amount injected before the intake stroke is subtracted from the latest required injection amount. A second injection amount calculating means for calculating a second injection amount;
Second fuel injection for injecting fuel of the second injection amount calculated at the latest time within a range in which fuel injection can be completed by the intake valve closing timing so that the fuel injection is completed by the intake valve closing timing Means,
A fuel injection control device for an internal combustion engine, comprising: 前記第２の燃料噴射手段は、前記第２の噴射量算出手段により２回目の噴射量が算出される毎に、吸気弁閉時期までの時間と２回目の噴射量の燃料噴射に要する時間との差を算出し、この差が所定値未満となっているときに、２回目の噴射量の燃料を噴射させることを特徴とする請求項２記載の内燃機関の燃料噴射制御装置。   Each time the second injection amount is calculated by the second injection amount calculation unit, the second fuel injection unit includes a time until the intake valve closing timing and a time required for fuel injection of the second injection amount. 3. The fuel injection control device for an internal combustion engine according to claim 2, wherein a difference between the two is calculated, and when the difference is less than a predetermined value, the second injection amount of fuel is injected. 前記第１の燃料噴射手段は、最新の要求噴射量から所定量を減算して、１回目の噴射量を算出することを特徴とする請求項１〜請求項３のいずれか１つに記載の内燃機関の燃料噴射制御装置。   4. The first fuel injection unit calculates a first injection amount by subtracting a predetermined amount from a latest required injection amount. 5. A fuel injection control device for an internal combustion engine. 前記第１の噴射量算出手段及び前記第１の燃料噴射手段は、各気筒の排気行程にて、１回目の噴射量を算出し、噴射させることを特徴とする請求項１〜請求項４のいずれか１つに記載の内燃機関の燃料噴射制御装置。   The first injection amount calculation means and the first fuel injection means calculate and inject the first injection amount in the exhaust stroke of each cylinder. The fuel injection control device for an internal combustion engine according to any one of the above.
JP2006169272A 2006-06-19 2006-06-19 Fuel injection control device of internal combustion engine Pending JP2007332944A (en)

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US7881856B2 (en) 2008-04-03 2011-02-01 Hitachi, Ltd. Apparatus for and method of controlling fuel injection of engine
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JP2009250082A (en) * 2008-04-03 2009-10-29 Hitachi Ltd Apparatus for controlling fuel injection of engine
US7881856B2 (en) 2008-04-03 2011-02-01 Hitachi, Ltd. Apparatus for and method of controlling fuel injection of engine
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