JP2008101579A - Control device of internal combustion engine - Google Patents

Control device of internal combustion engine Download PDF

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JP2008101579A
JP2008101579A JP2006286115A JP2006286115A JP2008101579A JP 2008101579 A JP2008101579 A JP 2008101579A JP 2006286115 A JP2006286115 A JP 2006286115A JP 2006286115 A JP2006286115 A JP 2006286115A JP 2008101579 A JP2008101579 A JP 2008101579A
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cylinder
amount
throttle valve
intake
intake throttle
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JP4457411B2 (en
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Tomoaki Nakano
智章 中野
Hideki Suzuki
英樹 鈴木
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Denso Corp
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Denso Corp
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Priority to US11/907,448 priority patent/US7597087B2/en
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  • Control Of Throttle Valves Provided In The Intake System Or In The Exhaust System (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a variation in the rotation of an engine due to a variation in the leaked air amount from an intake throttle valve for each cylinder of a system having the intake throttle valve in the intake manifold of each cylinder of the engine. <P>SOLUTION: An EGR increasing control for increasing an EGR amount during the low-load operation of the engine is performed. During the EGR increasing control, a varied rotation amount ΔNe (#1) to ΔNe (#4) in the rotational speed decreasing direction of each cylinder relative to the averaged rotational speed Ne (av) of all cylinders are obtained. The cylinder corresponding to the maximum varied rotation amount (max) among these cylinders is determined to be a cylinder with large leaked air amount (a cylinder from which a large air amount leaks). The opening of the intake throttle valve is corrected according to the leaked air amount from the intake throttle valve of the cylinder with large leaked air amount by correcting the opening of the intake throttle valve according to the maximum rotation varied amount ΔNe (max) during the period corresponding to the suction stroke of the cylinder with large leaked air amount. These treatments are repeatedly performed to suppress the variation in the rotation of the engine by correcting a variation in the intake air amount due to the dispersion of the leaked air amount from the intake throttle valve for each cylinder. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、内燃機関の各気筒の吸気通路にそれぞれ吸入空気量を調整する吸気絞り弁を備えた内燃機関の制御装置に関する発明である。   The present invention relates to a control device for an internal combustion engine provided with an intake throttle valve for adjusting an intake air amount in each intake passage of each cylinder of the internal combustion engine.

例えば、特許文献１（特許第２５３６２４２号公報）に記載されているように、内燃機関の各気筒の吸気通路に、それぞれ吸入空気量を調整する遮断弁（いわゆるスロットルバルブ）と該遮断弁をバイパスするパイパス通路とを設けると共に、各気筒のバイパス通路に、それぞれバイパス通路を開閉する制御弁（いわゆるアイドルスピードコントロールバルブ）を設け、アイドル運転時に、各気筒の吸気通路に設けた遮断弁を全閉にして、各気筒のバイパス通路に設けた制御弁の開弁時間を制御することで、吸入空気量を調整してアイドル回転速度を制御するようにしたシステムがある。   For example, as described in Patent Document 1 (Japanese Patent No. 2536242), a shut-off valve (so-called throttle valve) that adjusts the intake air amount and bypass the shut-off valve in the intake passage of each cylinder of the internal combustion engine. A bypass passage for each cylinder, and a control valve (so-called idle speed control valve) that opens and closes the bypass passage in each cylinder, and fully shuts off the shut-off valve provided in the intake passage of each cylinder during idle operation. Thus, there is a system in which the idle rotation speed is controlled by adjusting the intake air amount by controlling the valve opening time of the control valve provided in the bypass passage of each cylinder.

このようなシステムでは、アイドル運転時に、各気筒のバイパス通路に設けた制御弁の開弁時間を同一にしても、各気筒の吸気通路に設けた遮断弁の漏れ空気量（遮断弁の全閉時に遮断弁と吸気通路内壁面との小さな隙間を通過する空気量）が製造公差や経時変化等によって気筒間でばらつくと、各気筒の吸入空気量にばらつきが生じるため、各気筒のトルクがばらついてアイドル回転速度が大きく変動してしまう可能性がある。   In such a system, during idle operation, even if the valve opening time of the control valve provided in the bypass passage of each cylinder is the same, the leakage air amount of the shut-off valve provided in the intake passage of each cylinder (fully shutting off the shut-off valve) When the amount of air passing through a small gap between the shut-off valve and the intake passage inner wall sometimes varies between cylinders due to manufacturing tolerances, changes over time, etc., the intake air amount of each cylinder varies and the torque of each cylinder varies. Therefore, there is a possibility that the idling speed will fluctuate greatly.

この対策として、上記特許文献１では、アイドル運転時に、各気筒の爆発行程における回転速度を検出すると共に、全気筒の平均回転速度を算出し、各気筒の回転速度と全気筒の平均回転速度との差に応じて、それぞれ各気筒のバイパス通路に設けた制御弁の開弁時間を補正するようにしている。
特許第２５３６２４２号公報（第１頁〜第３頁等） As a countermeasure against this, in Patent Document 1, during the idling operation, the rotation speed of each cylinder in the explosion stroke is detected, the average rotation speed of all cylinders is calculated, and the rotation speed of each cylinder and the average rotation speed of all cylinders are calculated. In accordance with the difference, the opening time of the control valve provided in the bypass passage of each cylinder is corrected.
Japanese Patent No. 2536242 (first page to third page, etc.)

しかし、上記特許文献１の技術は、各気筒の吸気通路に設けた遮断弁を全閉にするアイドル運転時に各気筒のバイパス通路に設けた制御弁の開弁時間を補正することで、アイドル運転時に各気筒の遮断弁の漏れ空気量のばらつき等による各気筒の吸入空気量のばらつきを補正する技術であるため、各気筒の吸気通路に設けた遮断弁を開弁する運転領域では、各気筒の遮断弁の漏れ空気量のばらつきによる各気筒の吸入空気量のばらつきを補正することができず、各気筒の遮断弁の漏れ空気量のばらつきによる内燃機関の回転変動を抑制することができないという問題がある。   However, the technique disclosed in Patent Document 1 corrects the valve opening time of the control valve provided in the bypass passage of each cylinder during idle operation in which the shut-off valve provided in the intake passage of each cylinder is fully closed. Since this is a technique that compensates for variations in the intake air amount of each cylinder due to variations in the amount of air leaked from the shut-off valve of each cylinder at times, in the operating region where the shut-off valve provided in the intake passage of each cylinder is opened, each cylinder The variation in intake air amount in each cylinder due to the variation in the leakage air amount of the shut-off valve cannot be corrected, and the fluctuation in the rotation speed of the internal combustion engine due to the variation in the leakage air amount of the shut-off valve in each cylinder cannot be suppressed. There's a problem.

しかも、上記特許文献１の技術を適用するには、各気筒の吸気通路にそれぞれバイパス通路を設けると共に、各気筒のバイパス通路にそれぞれ制御弁を設ける必要があるため、システム構成が複雑化してコストアップするという欠点もある。   In addition, in order to apply the technique of Patent Document 1, it is necessary to provide a bypass passage in each intake passage of each cylinder and to provide a control valve in each bypass passage of each cylinder. There is also a drawback of up.

本発明は、これらの事情を考慮してなされたものであり、従って本発明の目的は、内燃機関の各気筒の吸気通路にそれぞれ吸気絞り弁を備えたシステムにおいて、各気筒の吸気絞り弁の漏れ空気量のばらつきによる吸入空気量のばらつきを精度良く補正することができて、各気筒の吸気絞り弁の漏れ空気量のばらつきによる内燃機関の回転変動を抑制することができると共に、低コスト化の要求を満たすことができる内燃機関の制御装置を提供することにある。   The present invention has been made in consideration of these circumstances. Therefore, an object of the present invention is to provide an intake throttle valve for each cylinder in a system having an intake throttle valve in each intake passage of each cylinder of an internal combustion engine. The variation in intake air amount due to the variation in leak air amount can be corrected with high accuracy, and the fluctuation in the rotational speed of the internal combustion engine due to the variation in the leak air amount of the intake throttle valve of each cylinder can be suppressed and the cost can be reduced. An object of the present invention is to provide a control device for an internal combustion engine that can satisfy the above requirements.

上記目的を達成するために、請求項１に係る発明は、内燃機関の各気筒の吸気通路にそれぞれ吸入空気量を調整する吸気絞り弁を備えた内燃機関の制御装置において、吸気絞り弁が混合気を均一化するための気流を発生させる機能を有し、内燃機関の排気還流量を調整する排気還流調整手段を設け、内燃機関の低負荷運転時に排気還流量を増加させるように排気還流調整手段を制御する排気還流増加制御を排気還流増加制御手段により実行し、この排気還流増加制御中に各気筒の吸気絞り弁の全閉時の漏れ空気量の情報として各気筒の燃焼状態を気筒別漏れ空気量情報検出手段により検出し、検出した各気筒の燃焼状態に基づいて漏れ空気量が多い気筒（以下「漏れ空気量大気筒」という）を漏れ空気量大気筒判定手段により判定し、この漏れ空気量大気筒の吸気行程に対応する期間に該漏れ空気量大気筒の燃焼状態に応じて吸気絞り弁の開度を気筒別吸気絞り弁開度補正手段により補正するようにしたものである。   In order to achieve the above object, according to a first aspect of the present invention, there is provided a control device for an internal combustion engine including an intake throttle valve for adjusting an intake air amount in an intake passage of each cylinder of the internal combustion engine. Exhaust gas recirculation adjustment means that adjusts the exhaust gas recirculation amount of the internal combustion engine with the function of generating an air flow to make the air uniform, and adjusts the exhaust gas recirculation amount to increase the exhaust gas recirculation amount during low-load operation of the internal combustion engine The exhaust gas recirculation increase control means for controlling the means is executed by the exhaust gas recirculation increase control means, and during this exhaust recirculation increase control, the combustion state of each cylinder is classified by cylinder as information on the leakage air amount when the intake throttle valve of each cylinder is fully closed. A cylinder having a large amount of leaked air (hereinafter referred to as “large cylinder of leaked air”) is determined by means of a cylinder for determining large amount of leaked air based on the detected combustion state of each cylinder. Leakage It is obtained so as to correct the period 該漏 Re air amount larger cylinder of the combustion state cylinder intake throttle valve opening compensation means the opening degree of the intake throttle valve in accordance with a corresponding to the intake stroke of the air amount larger cylinder.

吸気絞り弁が混合気を均一化するための気流（例えばタンブル流やスワール流）を発生させる機能を有する場合、吸気絞り弁の漏れ空気量が多くなると、その分、吸気絞り弁によって発生する気流強度が弱くなって混合気の均一化効果が低下するため、排気還流の影響が大きい内燃機関の低負荷運転時に排気還流量を増加させると、吸気絞り弁の漏れ空気量が多い気筒では、排気還流の影響で更に混合気の均一化効果が低下して燃焼状態が不安定になる。   When the intake throttle valve has a function of generating an air flow (for example, a tumble flow or a swirl flow) for making the air-fuel mixture uniform, if the amount of air leaked from the intake throttle valve increases, the air flow generated by the intake throttle valve If the exhaust gas recirculation amount is increased during low-load operation of an internal combustion engine where the influence of exhaust gas recirculation is large, the exhaust gas is reduced in the cylinder with a large amount of air leakage of the intake throttle valve. The effect of recirculation further reduces the homogenization effect of the air-fuel mixture and makes the combustion state unstable.

このような特性に着目して、内燃機関の低負荷運転時に排気還流量を増加させるように排気還流調整手段を制御する排気還流増加制御を実行し、この排気還流増加制御中に各気筒の吸気絞り弁の漏れ空気量の情報として各気筒の燃焼状態を検出して、各気筒の燃焼状態に基づいて燃焼状態が不安定な気筒を判定することで、漏れ空気量大気筒（漏れ空気量が多い気筒）を精度良く判定することができる。更に、漏れ空気量大気筒の吸気行程に対応する期間に該漏れ空気量大気筒の燃焼状態（漏れ空気量の情報）に応じて吸気絞り弁の開度を補正すれば、漏れ空気量大気筒の吸気絞り弁の漏れ空気量に応じて吸気絞り弁の開度を補正することができる。これらの処理を繰り返し実行することで、各気筒の吸気絞り弁の漏れ空気量のばらつきによる吸入空気量のばらつきを精度良く補正することができ、各気筒の吸気絞り弁の漏れ空気量のばらつきによる内燃機関の回転変動を抑制することができる。   Focusing on such characteristics, exhaust recirculation increase control is performed to control the exhaust gas recirculation adjustment means so as to increase the exhaust gas recirculation amount during low load operation of the internal combustion engine. During this exhaust recirculation increase control, the intake air of each cylinder is controlled. By detecting the combustion state of each cylinder as information on the amount of leakage air from the throttle valve, and determining the cylinder whose combustion state is unstable based on the combustion state of each cylinder, a large amount of leakage air (the amount of leakage air is Many cylinders) can be accurately determined. Further, if the opening degree of the intake throttle valve is corrected according to the combustion state (information on the leakage air amount) of the large leakage air amount cylinder during the period corresponding to the intake stroke of the large leakage air amount cylinder, the large leakage air amount cylinder The opening degree of the intake throttle valve can be corrected in accordance with the amount of air leaked from the intake throttle valve. By repeatedly executing these processes, it is possible to accurately correct the variation in the intake air amount due to the variation in the leakage air amount of the intake throttle valve of each cylinder, and due to the variation in the leakage air amount of the intake throttle valve of each cylinder. Rotational fluctuations of the internal combustion engine can be suppressed.

しかも、各気筒の吸気絞り弁をバイパスするバイパス通路や各気筒のバイパス通路を開閉する制御弁を設ける必要がないため、システム構成を簡単化して低コスト化することができる。   In addition, since it is not necessary to provide a bypass passage for bypassing the intake throttle valve of each cylinder and a control valve for opening and closing the bypass passage of each cylinder, the system configuration can be simplified and the cost can be reduced.

ここで、各気筒の燃焼状態に応じて各気筒の燃焼による回転変動が変化するため、請求項２のように、各気筒の燃焼状態を評価するパラメータとして各気筒の燃焼による回転変動を検出し、各気筒の燃焼による回転変動に基づいて燃焼状態が不安定な気筒を判定し、その気筒を漏れ空気量大気筒であると判定するようにしても良い。このようにすれば、各気筒の燃焼による回転変動に基づいて各気筒の燃焼状態を精度良く評価して、漏れ空気量大気筒を精度良く判定することができる。   Here, since the rotational fluctuation due to the combustion of each cylinder changes according to the combustion state of each cylinder, the rotational fluctuation due to the combustion of each cylinder is detected as a parameter for evaluating the combustion state of each cylinder as in claim 2. Alternatively, a cylinder having an unstable combustion state may be determined on the basis of rotation fluctuations due to combustion of each cylinder, and the cylinder may be determined to be a cylinder having a large amount of leakage air. In this way, it is possible to accurately evaluate the combustion state of each cylinder based on the rotational fluctuation caused by the combustion of each cylinder, and to accurately determine the cylinder having a large amount of leakage air.

具体的には、請求項３のように、各気筒の燃焼行程に対応する回転速度をそれぞれ全気筒の平均回転速度と比較して各気筒の燃焼による回転変動を検出し、平均回転速度に対する回転速度低下方向への回転変動量が最も大きい気筒を漏れ空気量大気筒であると判定するようにすると良い。つまり、漏れ空気量が多い気筒では、排気還流増加制御中に燃焼状態が不安定になって回転速度が低下するため、平均回転速度に対する回転速度低下方向への回転変動量が最も大きい気筒は漏れ空気量大気筒であると判定することができる。   Specifically, as in claim 3, the rotational speed corresponding to the combustion stroke of each cylinder is compared with the average rotational speed of all cylinders to detect rotational fluctuation due to combustion of each cylinder, and the rotational speed relative to the average rotational speed is detected. It is preferable to determine that the cylinder having the largest amount of fluctuation in rotation in the speed decreasing direction is the cylinder having a large leakage air amount. In other words, in a cylinder with a large amount of air leakage, the combustion state becomes unstable during exhaust gas recirculation increase control and the rotational speed decreases, so the cylinder with the largest amount of rotational fluctuation in the rotational speed decrease direction relative to the average rotational speed leaks. It can be determined that the cylinder has a large amount of air.

この場合、請求項４のように、平均回転速度に対する回転速度低下方向への回転変動量が最も大きく且つ該回転変動量が所定値以上となる気筒を漏れ空気量大気筒であると判定するようにしても良い。このようにすれば、平均回転速度に対する回転速度低下方向への回転変動量が最も大きい気筒であっても、その回転変動量が所定値よりも小さくて通常のばらつき範囲内となる気筒は漏れ空気量大気筒ではないと判定することができる。これにより、回転速度が平均回転速度よりも少し低いだけの気筒を漏れ空気量大気筒であると誤判定することを未然に防止できる。   In this case, as in claim 4, the cylinder having the largest amount of rotational fluctuation in the rotational speed lowering direction with respect to the average rotational speed and the rotational fluctuation amount equal to or greater than a predetermined value is determined to be a cylinder having a large leakage air amount. Anyway. In this way, even if the cylinder has the largest amount of rotational fluctuation in the rotational speed lowering direction with respect to the average rotational speed, the cylinder whose rotational fluctuation amount is smaller than the predetermined value and falls within the normal variation range is leaked air. It can be determined that the cylinder is not a large cylinder. Thus, it is possible to prevent erroneous determination that a cylinder whose rotational speed is slightly lower than the average rotational speed is a cylinder having a large leakage air amount.

以下、本発明を実施するための最良の形態を具体化した一実施例を説明する。
まず、図１に基づいてエンジン吸気系の概略構成を説明する。内燃機関である例えば直列４気筒のエンジン１１は、第１気筒＃１〜第４気筒＃４の４つの気筒を有し、このエンジン１１の吸気管１２には、サージタンク１３が設けられ、このサージタンク１３には、エンジン１１の各気筒に空気を導入する吸気マニホールド１４が設けられている。各気筒の吸気マニホールド１４には、それぞれ後述する吸気絞り弁ユニット１５が取り付けられ、各気筒の吸気ポート近傍には、それぞれ燃料を噴射する燃料噴射弁（図示せず）が取り付けられている。また、エンジン１１のシリンダヘッドには、各気筒毎に点火プラグ（図示せず）が取り付けられ、各点火プラグの火花放電によって筒内の混合気に着火される。更に、エンジン１１の排出ガスの一部を吸気側に還流させるためのＥＧＲ配管（図示せず）には、ＥＧＲ量（排気還流量）を調整するＥＧＲ弁３０（排気還流調整手段）が設けられている。 Hereinafter, an embodiment embodying the best mode for carrying out the present invention will be described.
First, a schematic configuration of the engine intake system will be described with reference to FIG. An in-line four-cylinder engine 11 that is an internal combustion engine, for example, has four cylinders, a first cylinder # 1 to a fourth cylinder # 4, and a surge tank 13 is provided in an intake pipe 12 of the engine 11. The surge tank 13 is provided with an intake manifold 14 that introduces air into each cylinder of the engine 11. An intake throttle valve unit 15 to be described later is attached to the intake manifold 14 of each cylinder, and a fuel injection valve (not shown) for injecting fuel is attached in the vicinity of the intake port of each cylinder. An ignition plug (not shown) is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by the spark discharge of each ignition plug. Furthermore, an EGR valve 30 (exhaust gas recirculation adjusting means) for adjusting the EGR amount (exhaust gas recirculation amount) is provided in an EGR pipe (not shown) for recirculating a part of the exhaust gas of the engine 11 to the intake side. ing.

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２５や、エンジン１１のクランク軸が所定クランク角回転する毎にパルス信号を出力するクランク角センサ２６が取り付けられている。このクランク角センサ２６の出力信号に基づいてクランク角やエンジン回転速度が検出される。更に、アクセルセンサ２７によってアクセル操作量（アクセルペダルの踏込量）が検出される。   A cooling water temperature sensor 25 that detects the cooling water temperature and a crank angle sensor 26 that outputs a pulse signal each time the crankshaft of the engine 11 rotates a predetermined crank angle are attached to the cylinder block of the engine 11. Based on the output signal of the crank angle sensor 26, the crank angle and the engine speed are detected. Further, the accelerator operation amount (depressed amount of the accelerator pedal) is detected by the accelerator sensor 27.

次に、図２に基づいて吸気絞り弁ユニット１５の構成について説明する。各気筒の吸気絞り弁ユニット１５は、樹脂製のハウジング１７内に、断面略四角形状の吸気通路１８が形成され、この吸気通路１８内に、該吸気通路１８を開閉する片持ち式の吸気絞り弁１９がその下端側に連結されたシャフト２０を回動軸にして開閉回動するように設けられている。各吸気絞り弁１９の形状は、吸気通路１８の断面形状に合致する形状（本実施例では略四角形状）に形成されている。尚、吸気通路１８の断面形状や吸気絞り弁１９の形状は、略四角形状に限定されず、略半円形状、略半楕円形状等、他の形状であっても良いことは言うまでもない。   Next, the configuration of the intake throttle valve unit 15 will be described with reference to FIG. In the intake throttle valve unit 15 of each cylinder, an intake passage 18 having a substantially square cross section is formed in a resin housing 17, and a cantilever intake throttle that opens and closes the intake passage 18 in the intake passage 18. The valve 19 is provided so as to open and close with a shaft 20 connected to the lower end thereof as a rotation axis. The shape of each intake throttle valve 19 is formed in a shape (substantially square shape in this embodiment) that matches the cross-sectional shape of the intake passage 18. Needless to say, the cross-sectional shape of the intake passage 18 and the shape of the intake throttle valve 19 are not limited to a substantially rectangular shape, and may be other shapes such as a substantially semicircular shape and a substantially semielliptical shape.

各気筒の吸気絞り弁１９は、共通のシャフト２０に連結されて一体的に回動するように設けられ、このシャフト２０に連結されたモータ２１（図１参照）がエンジン運転状態（アクセル操作量等）に応じて制御されることで、各気筒の吸気絞り弁１９の開度が制御されるようになっている。この吸気絞り弁１９の開度が吸気絞り弁開度センサ２９（図１参照）によって検出される。   The intake throttle valve 19 of each cylinder is connected to a common shaft 20 so as to rotate integrally, and a motor 21 (see FIG. 1) connected to the shaft 20 is in an engine operating state (accelerator operation amount). Etc.), the opening degree of the intake throttle valve 19 of each cylinder is controlled. The opening degree of the intake throttle valve 19 is detected by an intake throttle valve opening sensor 29 (see FIG. 1).

各気筒の吸気絞り弁１９は、シャフト２０側の端部（下端部）がハウジング１７の内壁面に接触（又は近接）するように設けられ、吸入空気が吸気絞り弁１９の下側をほとんど通過できないようになっている。そして、吸気絞り弁１９を開弁したときに、吸気絞り弁１９の上側のみに吸入空気の流路（ハウジング１７の内壁面との隙間）が形成されて、吸気絞り弁１９の開度に応じて吸気絞り弁１９の上側の流路断面積が変化するようになっている。これにより、吸気絞り弁１９の開度が比較的小さくなるエンジン１１の低負荷運転時には、吸気通路１８の上部側のみに吸入空気を流して吸入空気の流速を速めることで、筒内の混合気を均一化するための気流（例えばタンブル流やスワール流）を発生させるようになっている。   The intake throttle valve 19 of each cylinder is provided so that the end (lower end) on the shaft 20 side is in contact with (or close to) the inner wall surface of the housing 17, and the intake air almost passes under the intake throttle valve 19. I can't do it. When the intake throttle valve 19 is opened, an intake air flow path (a gap with the inner wall surface of the housing 17) is formed only on the upper side of the intake throttle valve 19, depending on the opening of the intake throttle valve 19. Thus, the channel cross-sectional area on the upper side of the intake throttle valve 19 changes. As a result, when the engine 11 is operated at a low load when the opening degree of the intake throttle valve 19 is relatively small, the intake air is flowed only to the upper side of the intake passage 18 to increase the flow rate of the intake air, whereby the air-fuel mixture in the cylinder An air flow (for example, a tumble flow or a swirl flow) is generated to make the air flow uniform.

また、ハウジング１７やその近傍には、吸気絞り弁１９の全開時に吸気絞り弁１９を格納する格納凹部２２が形成され、吸気絞り弁１９の全開時に吸気絞り弁１９が吸入空気流の妨げにならないようになっている。   A housing recess 22 for storing the intake throttle valve 19 when the intake throttle valve 19 is fully opened is formed in the housing 17 and the vicinity thereof, and the intake throttle valve 19 does not hinder the intake air flow when the intake throttle valve 19 is fully opened. It is like that.

上述した各種センサの出力は、制御回路（以下「ＥＣＵ」と表記する）２８に入力される。このＥＣＵ２８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）に記憶された各種のエンジン制御プログラムを実行することで、エンジン運転状態に応じて燃料噴射弁の燃料噴射量や点火プラグの点火時期を制御する。   Outputs of the various sensors described above are input to a control circuit (hereinafter referred to as “ECU”) 28. The ECU 28 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium), so that the fuel injection amount and ignition of the fuel injection valve according to the engine operating state. Control the ignition timing of the plug.

更に、ＥＣＵ２８は、アクセルセンサ２７で検出したアクセル操作量等に基づいて吸気絞り弁１９の目標開度を算出し、吸気絞り弁１９の実開度を目標開度に一致させるように吸気絞り弁１９のモータ２１を制御する。   Further, the ECU 28 calculates the target opening degree of the intake throttle valve 19 based on the accelerator operation amount detected by the accelerator sensor 27 and the intake throttle valve so that the actual opening degree of the intake throttle valve 19 coincides with the target opening degree. 19 motors 21 are controlled.

ところで、各気筒の吸気マニホールド１４に設けた吸気絞り弁１９の漏れ空気量（吸気絞り弁１９の全閉時に吸気絞り弁１９と吸気通路内壁面との隙間を通過する空気量）が製造公差や経時変化等によって気筒間でばらつくと、各気筒の吸入空気量にばらつきが生じるため、各気筒のトルクがばらついてエンジン回転速度が大きく変動してしまう可能性がある。   Incidentally, the amount of air leaked from the intake throttle valve 19 provided in the intake manifold 14 of each cylinder (the amount of air passing through the gap between the intake throttle valve 19 and the inner wall surface of the intake passage when the intake throttle valve 19 is fully closed) is a manufacturing tolerance or If the cylinders vary due to changes over time or the like, the amount of intake air in each cylinder varies, and therefore the torque of each cylinder varies and the engine rotation speed may vary greatly.

この対策として、ＥＣＵ２８は、後述する図４の気筒別吸気絞り弁開度補正プログラムを実行することで、次のようにして各気筒の漏れ空気量に応じて吸気絞り弁１９の開度を補正する気筒別吸気絞り弁開度補正を実行する。   As a countermeasure against this, the ECU 28 corrects the opening of the intake throttle valve 19 in accordance with the amount of air leaked from each cylinder as follows by executing a cylinder-specific intake throttle valve opening correction program shown in FIG. The cylinder-specific intake throttle valve opening correction is executed.

吸気絞り弁１９が混合気を均一化するための気流（例えばタンブル流やスワール流）を発生させる機能を有する場合、吸気絞り弁１９の漏れ空気量が多くなると、その分、吸気絞り弁１９によって発生する気流強度が弱くなって混合気の均一化効果が低下するため、ＥＧＲの影響が大きいエンジン１１の低負荷運転時にＥＧＲ量を増加させると、図３のタイムチャートに実線で示すように、吸気絞り弁１９の漏れ空気量が多い気筒（例えば第２気筒＃２）では、ＥＧＲの影響で更に混合気の均一化効果が低下して燃焼状態が不安定になって燃焼行程に対応する回転速度が通常のばらつき範囲を越えて大きく低下する。   When the intake throttle valve 19 has a function of generating an air flow (for example, a tumble flow or a swirl flow) for making the air-fuel mixture uniform, if the amount of air leaked from the intake throttle valve 19 increases, the intake throttle valve 19 Since the generated airflow intensity is weakened and the effect of homogenizing the air-fuel mixture is reduced, if the EGR amount is increased during low load operation of the engine 11 where the influence of EGR is large, as shown by the solid line in the time chart of FIG. In the cylinder (for example, the second cylinder # 2) where the amount of air leaked from the intake throttle valve 19 is large, the effect of equalizing the air-fuel mixture is further reduced due to the effect of EGR, the combustion state becomes unstable, and the rotation corresponding to the combustion stroke The speed is greatly reduced beyond the normal variation range.

このような特性に着目して、まず、エンジン１１の低負荷運転時にＥＧＲ量を増加させるようにＥＧＲ弁３０を制御するＥＧＲ増加制御を実行し、このＥＧＲ増加制御中に各気筒の燃焼状態を評価するパラメータとして各気筒の燃焼による回転変動を検出して、各気筒の燃焼による回転変動に基づいて燃焼状態が不安定な気筒を判定し、その気筒を漏れ空気量大気筒（漏れ空気量が多い気筒）であると判定する。   Focusing on such characteristics, first, EGR increase control for controlling the EGR valve 30 to increase the EGR amount during low load operation of the engine 11 is executed, and the combustion state of each cylinder is controlled during the EGR increase control. As a parameter to be evaluated, rotation fluctuation due to combustion of each cylinder is detected, a cylinder having an unstable combustion state is determined based on rotation fluctuation due to combustion of each cylinder, and the cylinder has a large leakage air amount (leakage air amount is It is determined that there are many cylinders).

具体的には、図３のタイムチャートに示すように、ＥＧＲ増加制御中に各気筒（第１気筒＃１〜第４気筒＃４）の燃焼行程に対応する回転速度の最大値（ピーク値）をそれぞれ各気筒の回転速度Ｎe(#1) 〜Ｎe(#4) として算出すると共に、各気筒の回転速度Ｎe(#1) 〜Ｎe(#4) から全気筒の平均回転速度Ｎe(av) を算出し、全気筒の平均回転速度Ｎe(av) と各気筒の回転速度Ｎe(#1) 〜Ｎe(#4) との偏差を求めることで、全気筒の平均回転速度Ｎe(av) に対する各気筒の回転速度低下方向への回転変動量ΔＮe(#1) 〜ΔＮe(#4) を求める。
ΔＮe(#i) ＝Ｎe(av) −Ｎe(#i)
ここで、ｉ＝１〜４ Specifically, as shown in the time chart of FIG. 3, the maximum value (peak value) of the rotational speed corresponding to the combustion stroke of each cylinder (first cylinder # 1 to fourth cylinder # 4) during EGR increase control. Is calculated as the rotational speed Ne (# 1) to Ne (# 4) of each cylinder, and the average rotational speed Ne (av) of all cylinders from the rotational speed Ne (# 1) to Ne (# 4) of each cylinder. Is calculated, and the deviation between the average rotational speed Ne (av) of all cylinders and the rotational speeds Ne (# 1) to Ne (# 4) of the respective cylinders is obtained, whereby the average rotational speed Ne (av) of all the cylinders is obtained. The rotational fluctuation amount ΔNe (# 1) to ΔNe (# 4) in the direction of decreasing the rotational speed of each cylinder is obtained.
ΔNe (#i) = Ne (av) −Ne (#i)
Where i = 1-4

この後、所定期間（例えば７２０℃Ａ期間）における各気筒の回転変動量ΔＮe(#1) 〜ΔＮe(#4) の中から最も大きい最大回転変動量ΔＮe(max)を判別し、この最大回転変動量ΔＮe(max)が所定値以上であれば、その最大回転変動量ΔＮe(max)に対応する気筒を漏れ空気量大気筒であると判定する。つまり、漏れ空気量が多い気筒では、ＥＧＲ増加制御中に燃焼状態が不安定になって回転速度が通常のばらつき範囲を越えて大きく低下するため、全気筒の平均回転速度Ｎe(av) に対する回転速度低下方向への回転変動量ΔＮe が最も大きく且つ該回転変動量ΔＮe が所定値以上となる気筒を漏れ空気量大気筒であると判定する。   Thereafter, the largest maximum rotational fluctuation amount ΔNe (max) is determined from the rotational fluctuation amounts ΔNe (# 1) to ΔNe (# 4) of each cylinder in a predetermined period (for example, 720 ° C. period A), and this maximum rotation is determined. If the fluctuation amount ΔNe (max) is equal to or greater than a predetermined value, it is determined that the cylinder corresponding to the maximum rotation fluctuation amount ΔNe (max) is a cylinder with a large leakage air amount. That is, in a cylinder with a large amount of air leakage, the combustion state becomes unstable during the EGR increase control, and the rotation speed greatly decreases beyond the normal variation range. Therefore, the rotation with respect to the average rotation speed Ne (av) of all the cylinders A cylinder in which the rotational fluctuation amount ΔNe in the speed decreasing direction is the largest and the rotational fluctuation amount ΔNe is equal to or greater than a predetermined value is determined to be a cylinder having a large leakage air amount.

この後、漏れ空気量大気筒の吸気行程に対応する期間に、該漏れ空気量大気筒の吸気絞り弁１９の漏れ空気量を反映した最大回転変動量ΔＮe(max)に応じて吸気絞り弁１９の開度を補正することで、漏れ空気量大気筒の吸気絞り弁１９の漏れ空気量に応じて吸気絞り弁１９の開度を補正する。   Thereafter, during a period corresponding to the intake stroke of the large cylinder of leaked air, the intake throttle valve 19 according to the maximum rotation fluctuation amount ΔNe (max) reflecting the leaked air quantity of the intake throttle valve 19 of the large cylinder of leaked air. Is corrected in accordance with the amount of air leaked from the intake throttle valve 19 of the cylinder having a large leaked air amount.

これらの処理（ＥＧＲ増加制御中に各気筒の回転変動を検出する処理と、各気筒の回転変動に基づいて漏れ空気量大気筒を判定する処理と、漏れ空気量大気筒の吸気行程に対応する期間に吸気絞り弁１９の開度を補正する処理）を繰り返し実行することで、各気筒の吸気絞り弁１９の漏れ空気量のばらつきによる吸入空気量のばらつきを精度良く補正して、各気筒の吸気絞り弁１９の漏れ空気量のばらつきによるエンジン回転変動を抑制する。   These processes (a process for detecting the rotation fluctuation of each cylinder during the EGR increase control, a process for determining a cylinder having a large leakage air amount based on the rotation fluctuation of each cylinder, and an intake stroke of the cylinder having a large leakage air amount) By repeatedly executing the process of correcting the opening of the intake throttle valve 19 during the period, the variation in intake air amount due to the variation in the leak air amount of the intake throttle valve 19 of each cylinder is accurately corrected, and The engine rotation fluctuation due to the variation in the air leakage amount of the intake throttle valve 19 is suppressed.

以下、ＥＣＵ２８が実行する図４の気筒別吸気絞り弁開度補正プログラムの処理内容を説明する。   The processing contents of the cylinder-specific intake throttle valve opening degree correction program of FIG. 4 executed by the ECU 28 will be described below.

［気筒別吸気絞り弁開度補正プログラム］
図４に示す気筒別吸気絞り弁開度補正プログラムは、ＥＣＵ２８の電源オン中に所定周期で実行される。本プログラムが起動されると、まず、ステップ１０１で、エンジン１１の低負荷運転時であるか否かを判定し、エンジン１１の低負荷運転時であると判定されれば、ステップ１０２に進み、ＥＧＲ量を増加させるようにＥＧＲ弁３０を制御するＥＧＲ増加制御を実行する。このステップ１０２の処理が特許請求の範囲でいう排気還流増加制御手段としての役割を果たす。 [Cylinder-specific intake throttle valve opening correction program]
The cylinder-specific intake throttle valve opening correction program shown in FIG. 4 is executed at a predetermined cycle while the ECU 28 is powered on. When this program is started, first, in step 101, it is determined whether or not the engine 11 is in a low load operation. If it is determined that the engine 11 is in a low load operation, the process proceeds to step 102. EGR increase control for controlling the EGR valve 30 to increase the EGR amount is executed. The processing in step 102 serves as exhaust gas recirculation increase control means in the claims.

この後、ステップ１０３に進み、全気筒のＥＧＲ量が増加したか否かを、例えば、全気筒のＥＧＲ量が増加するのに必要な所定期間が経過したか否かによって判定し、全気筒のＥＧＲ量が増加したと判定されたときに、ステップ１０４に進み、ＥＧＲ増加制御中にクランク角センサ２６の出力に基づいて各気筒の燃焼行程に対応する回転速度の最大値（ピーク値）をそれぞれ各気筒の回転速度Ｎe(#1) 〜Ｎe(#4) として算出した後、ステップ１０５に進み、各気筒の回転速度Ｎe(#1) 〜Ｎe(#4) から全気筒の平均回転速度Ｎe(av) を算出する。   Thereafter, the routine proceeds to step 103, where it is determined whether or not the EGR amount of all the cylinders has increased, for example, depending on whether or not a predetermined period required to increase the EGR amount of all the cylinders has elapsed. When it is determined that the EGR amount has increased, the routine proceeds to step 104 where the maximum value (peak value) of the rotational speed corresponding to the combustion stroke of each cylinder is determined based on the output of the crank angle sensor 26 during EGR increase control. After calculating as the rotational speed Ne (# 1) to Ne (# 4) of each cylinder, the process proceeds to step 105, and the average rotational speed Ne of all the cylinders from the rotational speed Ne (# 1) to Ne (# 4) of each cylinder. (av) is calculated.

この後、ステップ１０６に進み、全気筒の平均回転速度Ｎe(av) と各気筒の回転速度Ｎe(#1) 〜Ｎe(#4) との偏差を求めることで、全気筒の平均回転速度Ｎe(av) に対する各気筒の回転速度低下方向への回転変動量ΔＮe(#1) 〜ΔＮe(#4) を求める。
ΔＮe(#i) ＝Ｎe(av) −Ｎe(#i)
このステップ１０６の処理が特許請求の範囲でいう気筒別漏れ空気量情報検出手段としての役割を果たす。 Thereafter, the process proceeds to step 106, and the deviation between the average rotational speed Ne (av) of all the cylinders and the rotational speeds Ne (# 1) to Ne (# 4) of the respective cylinders is obtained to obtain the average rotational speed Ne of all the cylinders. Rotational fluctuation amounts ΔNe (# 1) to ΔNe (# 4) in the direction of decreasing the rotational speed of each cylinder with respect to (av) are obtained.
ΔNe (#i) = Ne (av) −Ne (#i)
The processing in step 106 serves as a cylinder-by-cylinder leakage air amount information detecting means in the claims.

この後、ステップ１０７に進み、所定期間（例えば７２０℃Ａ期間）における各気筒の回転変動量ΔＮe(#1) 〜ΔＮe(#4) の中から最も大きい最大回転変動量ΔＮe(max)を判別した後、ステップ１０８に進み、最大回転変動量ΔＮe(max)が所定値以上であるか否かを判定する。   Thereafter, the routine proceeds to step 107, where the largest maximum rotational fluctuation amount ΔNe (max) is determined from the rotational fluctuation amounts ΔNe (# 1) to ΔNe (# 4) of each cylinder in a predetermined period (for example, 720 ° C. period A). After that, the routine proceeds to step 108, where it is determined whether or not the maximum rotation fluctuation amount ΔNe (max) is a predetermined value or more.

このステップ１０８で、最大回転変動量ΔＮe(max)が所定値よりも小さいと判定された場合には、最大回転変動量ΔＮe(max)が通常のばらつき範囲内であるため、最大回転変動量ΔＮe(max)に対応する気筒は漏れ空気量大気筒ではないと判断して、本プログラムを終了する。   If it is determined in step 108 that the maximum rotation fluctuation amount ΔNe (max) is smaller than the predetermined value, the maximum rotation fluctuation amount ΔNe (max) is within the normal variation range, and thus the maximum rotation fluctuation amount ΔNe. It is determined that the cylinder corresponding to (max) is not a cylinder with a large amount of leakage air, and this program ends.

一方、上記ステップ１０８で、最大回転変動量ΔＮe(max)が所定値以上であると判定された場合には、最大回転変動量ΔＮe(max)が通常のばらつき範囲を越えているため、ステップ１０９に進み、その最大回転変動量ΔＮe(max)に対応する気筒を漏れ空気量大気筒であると判定する。   On the other hand, if it is determined in step 108 that the maximum rotation fluctuation amount ΔNe (max) is greater than or equal to a predetermined value, the maximum rotation fluctuation amount ΔNe (max) exceeds the normal variation range, and therefore, step 109 Then, it is determined that the cylinder corresponding to the maximum rotational fluctuation amount ΔNe (max) is a cylinder having a large leakage air amount.

この後、ステップ１１０に進み、漏れ空気量大気筒の吸気行程に対応する期間に、該漏れ空気量大気筒の吸気絞り弁１９の漏れ空気量を反映した最大回転変動量ΔＮe(max)に応じて吸気絞り弁１９の開度を補正することで、漏れ空気量大気筒の吸気絞り弁１９の漏れ空気量に応じて吸気絞り弁１９の開度を補正する。この場合、漏れ空気量のばらつきによる吸入空気量のばらつきを補正する方向に吸気絞り弁１９の開度を補正する。このステップ１１０の処理が特許請求の範囲でいう気筒別吸気絞り弁開度補正手段としての役割を果たす。   Thereafter, the process proceeds to step 110, and in a period corresponding to the intake stroke of the large cylinder of leaked air, according to the maximum rotational fluctuation amount ΔNe (max) reflecting the leaked air quantity of the intake throttle valve 19 of the large cylinder of leaked air. Thus, by correcting the opening degree of the intake throttle valve 19, the opening degree of the intake throttle valve 19 is corrected in accordance with the leakage air amount of the intake throttle valve 19 of the cylinder having a large leakage air amount. In this case, the opening degree of the intake throttle valve 19 is corrected in a direction in which the variation in the intake air amount due to the variation in the leaked air amount is corrected. The processing in step 110 serves as cylinder-specific intake throttle valve opening correction means in the claims.

本プログラムを繰り返し実行することで、各気筒の吸気絞り弁１９の漏れ空気量のばらつきによる吸入空気量のばらつきを精度良く補正して、各気筒の吸気絞り弁１９の漏れ空気量のばらつきによるエンジン回転変動を抑制する。   By repeatedly executing this program, the variation in the intake air amount due to the variation in the leak air amount of the intake throttle valve 19 of each cylinder is accurately corrected, and the engine due to the variation of the leak air amount of the intake throttle valve 19 of each cylinder. Suppresses rotational fluctuation.

以上説明した本実施例では、エンジン１１の低負荷運転中にＥＧＲ量を増加させると、吸気絞り弁１９の漏れ空気量が多い気筒では、ＥＧＲの影響で燃焼状態が不安定になって燃焼行程に対応する回転速度が大きく低下することに着目して、エンジン１１の低負荷運転時にＥＧＲ量を増加させるＥＧＲ増加制御中に全気筒の平均回転速度Ｎe(av) に対する各気筒の回転速度低下方向への回転変動量ΔＮe(#1) 〜ΔＮe(#4) を求め、その中の最大回転変動量ΔＮe(max)に対応する気筒を漏れ空気量大気筒であると判定する。そして、漏れ空気量大気筒の吸気行程に対応する期間に該漏れ空気量大気筒の吸気絞り弁１９の漏れ空気量を反映した最大回転変動量ΔＮe(max)に応じて吸気絞り弁１９の開度を補正することで、漏れ空気量大気筒の吸気絞り弁１９の漏れ空気量に応じて吸気絞り弁１９の開度を補正する。これらの処理を繰り返し実行することで、各気筒の吸気絞り弁１９の漏れ空気量のばらつきによる吸入空気量のばらつきを精度良く補正することができ、各気筒の吸気絞り弁１９の漏れ空気量のばらつきによるエンジン回転変動を抑制することができると共に、アイドル運転時にはアイドル回転速度の安定性を向上させることができる。   In the present embodiment described above, if the EGR amount is increased during low load operation of the engine 11, the combustion state becomes unstable due to the effect of EGR in the cylinder having a large amount of air leakage of the intake throttle valve 19, and the combustion stroke. In view of the fact that the rotational speed corresponding to is greatly reduced, during the EGR increase control for increasing the EGR amount during the low load operation of the engine 11, the rotational speed decreasing direction of each cylinder with respect to the average rotational speed Ne (av) of all the cylinders The rotation fluctuation amounts ΔNe (# 1) to ΔNe (# 4) are determined, and the cylinder corresponding to the maximum rotation fluctuation amount ΔNe (max) is determined to be a cylinder with a large leakage air amount. Then, the intake throttle valve 19 is opened according to the maximum rotation fluctuation amount ΔNe (max) reflecting the leak air amount of the intake throttle valve 19 of the large leak air amount cylinder during the period corresponding to the intake stroke of the large leak air amount cylinder. By correcting the degree, the opening degree of the intake throttle valve 19 is corrected in accordance with the leaked air amount of the intake throttle valve 19 of the cylinder with the large leaked air amount. By repeatedly executing these processes, it is possible to accurately correct the variation in the intake air amount due to the variation in the leak air amount of the intake throttle valve 19 of each cylinder, and to reduce the amount of leak air of the intake throttle valve 19 of each cylinder. The engine rotation fluctuation due to the variation can be suppressed, and the stability of the idle rotation speed can be improved during the idling operation.

しかも、各気筒の吸気絞り弁１９をバイパスするバイパス通路や各気筒のバイパス通路を開閉する制御弁を設ける必要がないため、システム構成を簡単化して低コスト化することができる。しかしながら、各気筒の吸気マニホールド１４にそれぞれ吸気絞り弁１９をバイパスするパイパス通路を設けると共に、各気筒のバイパス通路にそれぞれバイパス通路を開閉する制御弁を設けたシステムに本発明を適用しても良い。   In addition, since it is not necessary to provide a bypass passage for bypassing the intake throttle valve 19 of each cylinder and a control valve for opening and closing the bypass passage of each cylinder, the system configuration can be simplified and the cost can be reduced. However, the present invention may be applied to a system in which a bypass passage that bypasses the intake throttle valve 19 is provided in the intake manifold 14 of each cylinder, and a control valve that opens and closes the bypass passage is provided in the bypass passage of each cylinder. .

また、本実施例では、最大回転変動量ΔＮe(max)が所定値以上の場合には、最大回転変動量ΔＮe(max)が通常のばらつき範囲を越えているため、最大回転変動量ΔＮe(max)に対応する気筒を漏れ空気量大気筒であると判定するが、最大回転変動量ΔＮe(max)が所定値よりも小さい場合には、最大回転変動量ΔＮe(max)が通常のばらつき範囲内であるため、最大回転変動量ΔＮe(max)に対応する気筒は漏れ空気量大気筒ではないと判断するようにしたので、回転速度が平均回転速度よりも少し低いだけの気筒を漏れ空気量大気筒であると誤判定することを未然に防止できる。   In this embodiment, when the maximum rotation fluctuation amount ΔNe (max) is equal to or greater than a predetermined value, the maximum rotation fluctuation amount ΔNe (max) exceeds the normal variation range, and thus the maximum rotation fluctuation amount ΔNe (max ) Is determined to be a cylinder with a large amount of leakage air. If the maximum rotation fluctuation amount ΔNe (max) is smaller than a predetermined value, the maximum rotation fluctuation amount ΔNe (max) is within the normal variation range. Therefore, since the cylinder corresponding to the maximum rotation fluctuation amount ΔNe (max) is determined not to be a cylinder having a large amount of leakage air, a cylinder having a rotation speed slightly lower than the average rotation speed is set to a cylinder having a large amount of leakage air. It is possible to prevent erroneous determination as a cylinder.

尚、上記実施例では、ＥＧＲ増加制御中に全気筒の平均回転速度に対する回転速度低下方向への回転変動量が最も大きい気筒を漏れ空気量大気筒であると判定するようにしたが、ＥＧＲ増加制御の実行前と実行中との間で回転変動量が最も大きい気筒を漏れ空気量大気筒であると判定するようにしても良い。   In the above embodiment, during the EGR increase control, it is determined that the cylinder having the largest amount of rotational fluctuation in the rotational speed decreasing direction with respect to the average rotational speed of all the cylinders is the cylinder having the large leakage air amount. A cylinder having the largest amount of rotational fluctuation between before execution of control and during execution may be determined as a cylinder having a large leakage air amount.

また、上記実施例では、ＥＧＲ弁３０を制御して外部ＥＧＲ量を増加させるＥＧＲ増加制御を実行するようにしたが、吸気バルブや排気バルブのバルブタイミングを変化させる可変バルブタイミング装置を備えたシステムでは、吸気バルブと排気バルブのバルブオーバーラップ量を制御して内部ＥＧＲ量を増加させるＥＧＲ増加制御を実行するようにしても良い。   In the above embodiment, the EGR increase control for controlling the EGR valve 30 to increase the external EGR amount is executed. However, the system includes a variable valve timing device that changes the valve timing of the intake valve and the exhaust valve. Then, EGR increase control for increasing the internal EGR amount by controlling the valve overlap amount between the intake valve and the exhaust valve may be executed.

また、上記実施例では、本発明を４気筒エンジンに適用したが、２気筒エンジンや３気筒エンジン或は５気筒以上のエンジンに本発明を適用しても良い。   In the above embodiment, the present invention is applied to a four-cylinder engine. However, the present invention may be applied to a two-cylinder engine, a three-cylinder engine, or an engine having five or more cylinders.

また、上記実施例では、本発明を吸気ポート噴射エンジンに適用したが、筒内噴射エンジンや吸気ポートと筒内の両方に燃料噴射弁を設けたデュアル噴射エンジンに本発明を適用しても良い。   In the above embodiment, the present invention is applied to the intake port injection engine. However, the present invention may be applied to an in-cylinder injection engine or a dual injection engine provided with fuel injection valves in both the intake port and the cylinder. .

本発明の一実施例におけるエンジン制御システムの概略構成図である。It is a schematic block diagram of the engine control system in one Example of this invention. 吸気絞り弁ユニット及びその周辺部の構成を示す縦断面図である。It is a longitudinal cross-sectional view which shows the structure of an intake throttle valve unit and its peripheral part. 気筒別吸気絞り弁開度補正を説明するためのタイムチャートである。6 is a time chart for explaining cylinder-specific intake throttle valve opening correction. 気筒別吸気絞り弁開度補正プログラムの処理の流れを示すフローチャートである。It is a flowchart which shows the flow of a process of the intake throttle valve opening degree correction program classified by cylinder.

符号の説明Explanation of symbols

１１…エンジン（内燃機関）、１２…吸気管、１４…吸気マニホールド、１５…吸気絞り弁ユニット、１７…ハウジング、１９…吸気絞り弁、２１…モータ、２８…ＥＣＵ（排気還流増加制御手段，気筒別漏れ空気量情報検出手段，漏れ空気量大気筒判定手段，気筒別吸気絞り弁開度補正手段）、３０…ＥＧＲ弁（排気還流調整手段）   DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 14 ... Intake manifold, 15 ... Intake throttle valve unit, 17 ... Housing, 19 ... Intake throttle valve, 21 ... Motor, 28 ... ECU (Exhaust gas recirculation increase control means, Cylinder) Separate leakage air amount information detection means, leakage air amount large cylinder determination means, cylinder-specific intake throttle valve opening correction means), 30 ... EGR valve (exhaust gas recirculation adjustment means)

Claims (4)

内燃機関の各気筒の吸気通路にそれぞれ吸入空気量を調整する吸気絞り弁を備えた内燃機関の制御装置において、
前記吸気絞り弁が混合気を均一化するための気流を発生させる機能を有し、
内燃機関の排気還流量を調整する排気還流調整手段と、
内燃機関の低負荷運転時に前記排気還流量を増加させるように前記排気還流調整手段を制御する排気還流増加制御を実行する排気還流増加制御手段と、
前記排気還流増加制御中に各気筒の吸気絞り弁の全閉時の漏れ空気量の情報として各気筒の燃焼状態を検出する気筒別漏れ空気量情報検出手段と、
前記気筒別漏れ空気量情報検出手段で検出した各気筒の燃焼状態に基づいて前記漏れ空気量が多い気筒（以下「漏れ空気量大気筒」という）を判定する漏れ空気量大気筒判定手段と、
前記漏れ空気量大気筒の吸気行程に対応する期間に該漏れ空気量大気筒の燃焼状態に応じて前記吸気絞り弁の開度を補正する気筒別吸気絞り弁開度補正手段と
を備えていることを特徴とする内燃機関の制御装置。 In a control device for an internal combustion engine provided with an intake throttle valve for adjusting an intake air amount in each intake passage of each cylinder of the internal combustion engine,
The intake throttle valve has a function of generating an air flow for making the air-fuel mixture uniform;
Exhaust gas recirculation adjusting means for adjusting the exhaust gas recirculation amount of the internal combustion engine;
Exhaust gas recirculation increase control means for executing exhaust gas recirculation increase control for controlling the exhaust gas recirculation adjustment means so as to increase the exhaust gas recirculation amount during low load operation of the internal combustion engine;
Cylinder-by-cylinder leakage air amount information detection means for detecting the combustion state of each cylinder as information on the amount of leakage air when the intake throttle valve of each cylinder is fully closed during the exhaust gas recirculation increase control;
Leakage air amount large cylinder determination means for determining a cylinder having a large amount of leakage air (hereinafter referred to as “leakage air amount large cylinder”) based on the combustion state of each cylinder detected by the cylinder specific leakage air amount information detection means;
And a cylinder-specific intake throttle valve opening correction means for correcting the opening of the intake throttle valve in accordance with the combustion state of the large leaked air amount cylinder during a period corresponding to the intake stroke of the large leaked air amount cylinder. A control device for an internal combustion engine. 前記気筒別漏れ空気量情報検出手段は、各気筒の燃焼状態を評価するパラメータとして各気筒の燃焼による回転変動を検出し、
前記漏れ空気量大気筒判定手段は、各気筒の燃焼による回転変動に基づいて前記燃焼状態が不安定な気筒を判定し、その気筒を前記漏れ空気量大気筒であると判定することを特徴とする請求項１に内燃機関の制御装置。 The cylinder-by-cylinder leakage air amount information detecting means detects rotational fluctuation due to combustion of each cylinder as a parameter for evaluating the combustion state of each cylinder,
The cylinder having a large amount of leakage air determining means determines a cylinder having an unstable combustion state based on rotational fluctuation due to combustion of each cylinder, and determines that the cylinder is a cylinder having a large amount of leakage air. The control apparatus for an internal combustion engine according to claim 1. 前記気筒別漏れ空気量情報検出手段は、各気筒の燃焼行程に対応する回転速度をそれぞれ全気筒の平均回転速度と比較して各気筒の燃焼による回転変動を検出し、
前記漏れ空気量大気筒判定手段は、前記平均回転速度に対する回転速度低下方向への回転変動量が最も大きい気筒を前記漏れ空気量大気筒であると判定することを特徴とする請求項２に内燃機関の制御装置。 The cylinder-by-cylinder leakage air amount information detecting means detects the rotational fluctuation due to combustion of each cylinder by comparing the rotational speed corresponding to the combustion stroke of each cylinder with the average rotational speed of all the cylinders.
3. The internal combustion engine according to claim 2, wherein the cylinder having a large amount of leakage air determines that the cylinder having the largest amount of fluctuation in rotation in the direction of decreasing the rotation speed with respect to the average rotation speed is the cylinder having the large amount of leakage air. Engine control device. 前記漏れ空気量大気筒判定手段は、前記平均回転速度に対する回転速度低下方向への回転変動量が最も大きく且つ該回転変動量が所定値以上となる気筒を前記漏れ空気量大気筒であると判定することを特徴とする請求項３に内燃機関の制御装置。   The large leakage air amount cylinder determining means determines that the cylinder having the largest rotational fluctuation amount in the rotational speed decreasing direction with respect to the average rotational speed and the rotational fluctuation amount being equal to or greater than a predetermined value is the large leakage air amount cylinder. The control apparatus for an internal combustion engine according to claim 3.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2954408A1 (en) * 2009-12-22 2011-06-24 Valeo Sys Controle Moteur Sas METHOD FOR CONTROLLING AN EGR CIRCUIT OF A MOTOR VEHICLE ENGINE
FR2954407A1 (en) * 2009-12-22 2011-06-24 Valeo Sys Controle Moteur Sas METHOD FOR CONTROLLING AN EGR CIRCUIT OF A MOTOR VEHICLE MOTOR, VALVE FOR IMPLEMENTING THE METHOD AND ENGINE WITH THE VALVE.

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2954408A1 (en) * 2009-12-22 2011-06-24 Valeo Sys Controle Moteur Sas METHOD FOR CONTROLLING AN EGR CIRCUIT OF A MOTOR VEHICLE ENGINE
FR2954407A1 (en) * 2009-12-22 2011-06-24 Valeo Sys Controle Moteur Sas METHOD FOR CONTROLLING AN EGR CIRCUIT OF A MOTOR VEHICLE MOTOR, VALVE FOR IMPLEMENTING THE METHOD AND ENGINE WITH THE VALVE.
WO2011076901A1 (en) * 2009-12-22 2011-06-30 Valeo Systemes De Controle Moteur Method for controlling an egr circuit in a motor vehicle engine
WO2011076876A1 (en) * 2009-12-22 2011-06-30 Valeo Systemes De Controle Moteur Method for controlling an egr circuit of a motor vehicle engine, valve for implementing said method, and engine having said valve
US8862369B2 (en) 2009-12-22 2014-10-14 Valeo Systemes De Controle Moteur Method for controlling an EGR circuit of a motor vehicle engine, valve for implementing said method, and engine having said valve
US9145854B2 (en) 2009-12-22 2015-09-29 Valeo Systemes De Controle Moteur Method for controlling an EGR circuit in a motor vehicle engine

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