JP2006291871A - Controller of internal combustion engine - Google Patents

Controller of internal combustion engine Download PDF

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JP2006291871A
JP2006291871A JP2005114585A JP2005114585A JP2006291871A JP 2006291871 A JP2006291871 A JP 2006291871A JP 2005114585 A JP2005114585 A JP 2005114585A JP 2005114585 A JP2005114585 A JP 2005114585A JP 2006291871 A JP2006291871 A JP 2006291871A
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exhaust gas
gas recirculation
oxygen concentration
excess air
exhaust
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Masaki Ueno
将樹 上野
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Honda Motor Co Ltd
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Honda Motor Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/45—Sensors specially adapted for EGR systems
    • F02M26/46—Sensors specially adapted for EGR systems for determining the characteristics of gases, e.g. composition
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/02—EGR systems specially adapted for supercharged engines
    • F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
    • F02M26/05—High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust-Gas Circulating Devices (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller of an internal combustion engine capable of accurately estimating an oxygen concentration in an exhaust recirculation gas. <P>SOLUTION: The excess air ratio λ<SB>0</SB>of the exhaust recirculation gas flowing into an exhaust gas recirculation passage 5 is calculated according to the oxygen concentration OXCE detected by an oxygen concentration sensor 25 installed in an exhaust system. Also, an exhaust recirculation gas flow velocity V is calculated according to the operating state of an engine, and an excess air ratio λn of an exhaust recirculation gas flowing into an intake tube 2 is calculated by using an excess air ratio model in which the excess air ratio λ<SB>o</SB>and the exhaust recirculation gas flow velocity V are used as inputs. A fuel supply control is performed by using the excess air ratio λn. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、排気還流機構を備えた内燃機関の制御装置に関し、特に排気還流機構を介して還流される排気中の酸素濃度を推定する機能を備えた制御装置に関する。   The present invention relates to a control device for an internal combustion engine having an exhaust gas recirculation mechanism, and more particularly to a control device having a function of estimating an oxygen concentration in exhaust gas recirculated through an exhaust gas recirculation mechanism.

排気還流機構を備えた内燃機関において、空燃比を理論空燃比よりリーン側に設定するリーンバーン運転を行うと、排気に含まれる空気（酸素）の割合が大きくなるため、排気還流機構を介して吸気系に還流される排気還流ガス中の酸素濃度が高くなる。そのため、吸入空気流量センサにより新気流量を検出し、検出した新気流量に応じて所望の空燃比を得るための燃料供給量を決定すると、排気還流ガス中の酸素（空気）の影響により、空燃比が所望値よりリーン側にずれる。   In an internal combustion engine equipped with an exhaust gas recirculation mechanism, when a lean burn operation is performed in which the air-fuel ratio is set to be leaner than the stoichiometric air-fuel ratio, the ratio of air (oxygen) contained in the exhaust gas increases. The oxygen concentration in the exhaust gas recirculation gas that is recirculated to the intake system increases. Therefore, when the fresh air flow rate is detected by the intake air flow rate sensor and the fuel supply amount for obtaining a desired air-fuel ratio is determined according to the detected fresh air flow rate, due to the influence of oxygen (air) in the exhaust recirculation gas, The air-fuel ratio shifts to the lean side from the desired value.

特許文献１にはこの不具合をなくすための空燃比制御装置が示されている。この装置では、排気還流ガス中の空気量Ｑ２が算出され、この空気量Ｑ２から、排気還流ガスがシリンダまで到達するのに要する時間に対応する位相遅れを考慮した空気量Ｑ２’が算出される。そして、この空気量Ｑ２’を用いて内燃機関の気筒内に供給される実際の総空気量が求められ、その総空気量に応じて燃料供給量が決定される。   Patent Document 1 discloses an air-fuel ratio control device for eliminating this problem. In this apparatus, the air amount Q2 in the exhaust gas recirculation gas is calculated, and from this air amount Q2, the air amount Q2 ′ taking into account the phase delay corresponding to the time required for the exhaust gas recirculation gas to reach the cylinder is calculated. . Then, an actual total air amount supplied into the cylinder of the internal combustion engine is obtained using the air amount Q2 ', and the fuel supply amount is determined according to the total air amount.

特開平９−２８７５１０号公報JP-A-9-287510

特許文献１に示された空気量Ｑ２’は、空気量Ｑ２の最新の推定値と、過去の推定値との加重平均演算により、あるいは空気量Ｑ２の一次遅れ値として、推定される。しかしながら、この空気量推定手法では、排気還流機構を通過する排気還流ガスの流速が考慮されていないため、機関運転状態の変化によって推定精度が低下する場合があった。   The air amount Q2 'disclosed in Patent Document 1 is estimated by a weighted average calculation of the latest estimated value of the air amount Q2 and a past estimated value, or as a primary delay value of the air amount Q2. However, in this air amount estimation method, since the flow rate of the exhaust gas recirculation gas passing through the exhaust gas recirculation mechanism is not taken into account, the estimation accuracy may be reduced due to a change in the engine operating state.

本発明はこの点に着目してなされたものであり、排気還流ガス中の酸素濃度（空気過剰率）をより正確に推定することができる内燃機関の制御装置を提供することを目的とする。   The present invention has been made paying attention to this point, and an object of the present invention is to provide a control device for an internal combustion engine that can more accurately estimate the oxygen concentration (excess air ratio) in the exhaust gas recirculation gas.

上記目的を達成するため請求項１に記載の発明は、内燃機関（１）の排気の一部を吸気管（２）に還流する排気還流手段（５，６）と、排気中の酸素濃度（ＯＸＣＥ）を検出する酸素濃度検出手段（２３）とを備えた内燃機関の制御装置において、前記酸素濃度検出手段（２３）の出力及び排気還流ガスの流速（Ｖ）を入力とした空気過剰率モデルに基づいて、前記吸気管（２）に流入する排気還流ガス中の酸素濃度（ＯＸＣＲ）を推定する排気還流ガス酸素濃度推定手段を有することを特徴とする。   In order to achieve the above object, the invention described in claim 1 includes an exhaust gas recirculation means (5, 6) for recirculating a part of the exhaust gas of the internal combustion engine (1) to the intake pipe (2), and an oxygen concentration ( In the control device for an internal combustion engine provided with an oxygen concentration detection means (23) for detecting OXCE), an excess air ratio model using the output of the oxygen concentration detection means (23) and the flow velocity (V) of the exhaust recirculation gas as inputs. And exhaust gas recirculation gas oxygen concentration estimation means for estimating the oxygen concentration (OXCR) in the exhaust gas recirculation gas flowing into the intake pipe (2).

上記空気過剰率モデルは、前記排気還流手段を構成する排気還流通路を、長さ方向にｎ個（ｎは２以上の整数）の領域に分割したとき、第ｉ番目（１≦ｉ≦ｎ）の領域における空気過剰率λiが下記式により定義されるモデルである。
λi(k+1)＝（１−ａ）λi(k)＋ａλi-1(k)
ここで、ｋは演算周期で離散化した演算時刻、ａは前記排気還流ガス流速（Ｖ）に比例するモデルパラメータである。またλ0は、前記排気還流通路に流入する排気の空気過剰率に相当し、前記酸素濃度検出手段の出力に応じて算出される。 When the exhaust gas recirculation passage constituting the exhaust gas recirculation means is divided into n (n is an integer of 2 or more) regions in the length direction, the excess air ratio model is the i th (1 ≦ i ≦ n). excess air ratio lambda i in the regions are model defined by the following equation.
λ i (k + 1) = (1−a) λ i (k) + aλ i−1 (k)
Here, k is a calculation time discretized at a calculation cycle, and a is a model parameter proportional to the exhaust gas recirculation gas flow velocity (V). Λ 0 corresponds to the excess air ratio of the exhaust gas flowing into the exhaust gas recirculation passage, and is calculated according to the output of the oxygen concentration detection means.

請求項１に記載の発明によれば、酸素濃度検出手段の出力及び排気還流ガスの流速を入力とした空気過剰率モデルに基づいて、吸気管に流入する排気還流ガス中の酸素濃度が推定されるので、排気還流ガス中の酸素濃度（空気過剰率）をより正確に推定することができる。   According to the first aspect of the present invention, the oxygen concentration in the exhaust gas recirculation gas flowing into the intake pipe is estimated based on the excess air model using the output of the oxygen concentration detection means and the flow velocity of the exhaust gas recirculation gas as inputs. Therefore, the oxygen concentration (excess air ratio) in the exhaust gas recirculation gas can be estimated more accurately.

以下本発明の実施の形態を図面を参照して説明する。
図１は本発明の一実施形態にかかる内燃機関と、その制御装置の構成を示す図である。内燃機関（以下「エンジン」という）１は、シリンダ内に燃料を直接噴射するディーゼルエンジンであり、各気筒に燃料噴射弁９が設けられている。燃料噴射弁９は、電子制御ユニット（以下「ＥＣＵ」という）２０に電気的に接続されており、燃料噴射弁９の開弁時間は、ＥＣＵ２０により制御される。 Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration of an internal combustion engine and a control device thereof according to an embodiment of the present invention. An internal combustion engine (hereinafter referred to as “engine”) 1 is a diesel engine that directly injects fuel into a cylinder, and a fuel injection valve 9 is provided in each cylinder. The fuel injection valve 9 is electrically connected to an electronic control unit (hereinafter referred to as “ECU”) 20, and the valve opening time of the fuel injection valve 9 is controlled by the ECU 20.

エンジン１は、吸気管２，排気管４、及びターボチャージャ８を備えている。ターボチャージャ８は、排気の運動エネルギにより回転駆動されるタービンホイール１０を有するタービン１１と、タービンホイール１０とシャフト１４を介して連結されたコンプレッサホイール１５を有するコンプレッサ１６とを備えている。コンプレッサホイール１５は、エンジン１に吸入される空気の加圧（圧縮）を行う。   The engine 1 includes an intake pipe 2, an exhaust pipe 4, and a turbocharger 8. The turbocharger 8 includes a turbine 11 having a turbine wheel 10 that is rotationally driven by kinetic energy of exhaust, and a compressor 16 having a compressor wheel 15 connected to the turbine wheel 10 via a shaft 14. The compressor wheel 15 pressurizes (compresses) air sucked into the engine 1.

タービン１１は、タービンホイール１０に吹き付けられる排気ガスの流量を変化させるべく開閉駆動される複数の可変ベーン１２（２個のみ図示）及び該可変ベーンを開閉駆動するアクチュエータ（図示せず）を有しており、可変ベーン１２の開度（以下「ベーン開度」という）ＶＯを変化させることにより、タービンホイール１０に吹き付けられる排気ガスの流量を変化させ、タービンホイール１０の回転速度を変更できるように構成されている。可変ベーン１２を駆動するアクチュエータは、ＥＣＵ２０に接続されており、ベーン開度ＶＯは、ＥＣＵ２０により制御される。より具体的には、ＥＣＵ２０は、デューティ比可変の制御信号をアクチュエータに供給し、これによってベーン開度ＶＯを制御する。なお、可変ベーンを有するターボチャージャの構成は広く知られており、例えば特開平１−２０８５０１号公報に示されている。   The turbine 11 has a plurality of variable vanes 12 (only two are shown) that are driven to change the flow rate of exhaust gas blown to the turbine wheel 10, and an actuator (not shown) that drives the variable vanes to open and close. By changing the opening VO of the variable vane 12 (hereinafter referred to as “vane opening”), the flow rate of the exhaust gas blown to the turbine wheel 10 can be changed, and the rotational speed of the turbine wheel 10 can be changed. It is configured. The actuator that drives the variable vane 12 is connected to the ECU 20, and the vane opening VO is controlled by the ECU 20. More specifically, the ECU 20 supplies a control signal with a variable duty ratio to the actuator, thereby controlling the vane opening VO. The configuration of a turbocharger having a variable vane is widely known, and is disclosed in, for example, Japanese Patent Laid-Open No. 1-208501.

排気管４と吸気管２との間には、排気を吸気管２に環流する排気還流通路５が設けられている。排気還流通路５には、排気還流量を制御するための排気還流弁（以下「ＥＧＲ弁」という）６が設けられている。ＥＧＲ弁６は、ソレノイドを有する電磁弁であり、その弁開度はＥＣＵ２０により制御される。ＥＧＲ弁６には、その弁開度（弁リフト量）ＬＡＣＴを検出するリフトセンサ７が設けられており、その検出信号はＥＣＵ２０に供給される。排気還流通路５及びＥＧＲ弁６より、排気還流機構が構成される。   Between the exhaust pipe 4 and the intake pipe 2, an exhaust gas recirculation passage 5 that circulates exhaust gas to the intake pipe 2 is provided. The exhaust gas recirculation passage 5 is provided with an exhaust gas recirculation valve (hereinafter referred to as “EGR valve”) 6 for controlling the exhaust gas recirculation amount. The EGR valve 6 is an electromagnetic valve having a solenoid, and the valve opening degree is controlled by the ECU 20. The EGR valve 6 is provided with a lift sensor 7 for detecting the valve opening degree (valve lift amount) LACT, and the detection signal is supplied to the ECU 20. An exhaust gas recirculation mechanism is configured by the exhaust gas recirculation passage 5 and the EGR valve 6.

吸気管２には、吸入空気流量ＧＡを検出する吸入空気流量センサ２１、及びコンプレッサ１６の下流側の吸気圧（過給圧）Ｐ２を検出する過給圧センサ２２が設けられている。また、排気管４には、排気中の酸素濃度を検出する酸素濃度センサ２３が設けられている。これらのセンサ２１〜２３は、ＥＣＵ２０と接続されており、センサ２１〜２３の検出信号は、ＥＣＵ２０に供給される。   The intake pipe 2 is provided with an intake air flow rate sensor 21 that detects an intake air flow rate GA and a supercharging pressure sensor 22 that detects an intake pressure (supercharging pressure) P2 on the downstream side of the compressor 16. The exhaust pipe 4 is provided with an oxygen concentration sensor 23 for detecting the oxygen concentration in the exhaust. These sensors 21 to 23 are connected to the ECU 20, and detection signals from the sensors 21 to 23 are supplied to the ECU 20.

排気管４の、酸素濃度センサ２３の下流側には、排気ガス中に含まれる粒子状物質（主としてすすからなる）を捕集する粒子状物質フィルタ（以下「ＤＰＦ」という）１７が設けられている。
エンジン１により駆動される車両のアクセルペダル（図示せず）の踏み込み量（以下「アクセルペダル操作量」という）ＡＰを検出するアクセルセンサ２６、及びエンジン回転数（回転速度）ＮＥを検出するエンジン回転数センサ２７がＥＣＵ２０に接続されており、これらのセンサの検出信号は、ＥＣＵ２０に供給される。 A particulate matter filter (hereinafter referred to as “DPF”) 17 that collects particulate matter (mainly composed of soot) contained in the exhaust gas is provided on the exhaust pipe 4 downstream of the oxygen concentration sensor 23. Yes.
An accelerator sensor 26 that detects a depression amount (hereinafter referred to as “accelerator pedal operation amount”) AP of an accelerator pedal (not shown) of a vehicle driven by the engine 1 and an engine rotation that detects an engine speed (rotation speed) NE. A number sensor 27 is connected to the ECU 20, and detection signals from these sensors are supplied to the ECU 20.

ＥＣＵ２０は、各種センサからの入力信号波形を整形し、電圧レベルを所定レベルに修正し、アナログ信号値をデジタル信号値に変換する等の機能を有する入力回路、中央演算処理ユニット（以下「ＣＰＵ」という）、ＣＰＵで実行される各種演算プログラム及び演算結果等を記憶する記憶回路、タービン１１の可変ベーン１２を駆動するアクチュエータ、燃料噴射弁９、ＥＧＲ弁６などに駆動信号を供給する出力回路等から構成される。   The ECU 20 shapes input signal waveforms from various sensors, corrects the voltage level to a predetermined level, converts an analog signal value into a digital signal value, a central processing unit (hereinafter referred to as “CPU”). A storage circuit for storing various calculation programs executed by the CPU and calculation results, an actuator for driving the variable vane 12 of the turbine 11, an output circuit for supplying a drive signal to the fuel injection valve 9, the EGR valve 6, etc. Consists of

ＥＣＵ２０は、エンジン１の運転状態、具体的にはアクセルペダル操作量ＡＰ及びエンジン回転数ＮＥに応じて目標過給圧Ｐ２ＣＭＤを算出し、検出される過給圧Ｐ２が目標過給圧Ｐ２ＣＭＤと一致するようにベーン開度ＶＯの制御する過給圧制御を行う。さらにＥＣＵ２０は、アクセルペダル操作量ＡＰ及びエンジン回転数ＮＥに応じて燃料噴射弁９の開弁時間ＴＯＵＴを算出し、開弁時間ＴＯＵＴに応じた駆動信号を燃料噴射弁９に供給する。   The ECU 20 calculates the target boost pressure P2CMD according to the operating state of the engine 1, specifically, the accelerator pedal operation amount AP and the engine speed NE, and the detected boost pressure P2 matches the target boost pressure P2CMD. Thus, the supercharging pressure control for controlling the vane opening VO is performed. Further, the ECU 20 calculates the valve opening time TOUT of the fuel injection valve 9 according to the accelerator pedal operation amount AP and the engine speed NE, and supplies a drive signal corresponding to the valve opening time TOUT to the fuel injection valve 9.

ＥＣＵ２０は、さらにアクセルペダル操作量ＡＰ及びエンジン回転数ＮＥに応じて、目標吸入空気量ＧＡＣＭＤを設定し、目標吸入空気量ＧＡＣＭＤ及び検出される吸入空気流量ＧＡに基づいて排気還流量を決定し、ＥＧＲ弁６のリフト量（開弁量）を制御する。   The ECU 20 further sets a target intake air amount GACMD according to the accelerator pedal operation amount AP and the engine speed NE, determines an exhaust gas recirculation amount based on the target intake air amount GACMD and the detected intake air flow rate GA, The lift amount (valve opening amount) of the EGR valve 6 is controlled.

ＥＣＵ２０は、さらに以下に説明する手法により、排気還流通路５を介して還流される排気還流ガスの空気過剰率λ（酸素濃度）の推定を行う。
本実施形態では、排気還流通路５を通過する排気還流ガスの流速Ｖと、空気過剰率λが下記式（１）を満たす制御対象モデル（以下「空気過剰率モデル」という）を用いて、吸気管２に流入する排気還流ガスの空気過剰率を推定する。この空気過剰率モデルは、排気還流通路５内の空気過剰率の空間分布（図２参照）及び挙動（時間変化）をモデル化したものである。なお、式（１）の右辺が「０」となっているのは、排気還流通路５と外部との間で空気（新気）及び燃料の流入・流出がないことに対応するものである。

Figure 2006291871
ここで、ｘは、図２に示すように排気還流通路５の排気管側に入口を基準位置（ｘ＝０）とする排気還流通路５の長さ方向の座標である。 The ECU 20 further estimates the excess air ratio λ (oxygen concentration) of the exhaust gas recirculation gas that is recirculated through the exhaust gas recirculation passage 5 by the method described below.
In the present embodiment, the flow rate V of the exhaust gas recirculation gas passing through the exhaust gas recirculation passage 5 and the control target model (hereinafter referred to as “excess air ratio model”) in which the excess air ratio λ satisfies the following formula (1) The excess air ratio of the exhaust gas recirculation gas flowing into the pipe 2 is estimated. This excess air ratio model is obtained by modeling the spatial distribution (see FIG. 2) and behavior (time change) of the excess air ratio in the exhaust gas recirculation passage 5. Note that the right side of the expression (1) is “0”, which corresponds to the fact that there is no inflow / outflow of air (fresh air) and fuel between the exhaust gas recirculation passage 5 and the outside.
Figure 2006291871
 Here, x is a coordinate in the length direction of the exhaust gas recirculation passage 5 with the inlet at the reference position (x = 0) on the exhaust pipe side of the exhaust gas recirculation passage 5 as shown in FIG.

式（１）を差分方程式に変換すると、下記式（２）が得られ、これを変形すると、下記式（３）が得られる。式（２）のｋは、演算周期Δｔで離散化した演算時刻であり、ｉは、位置座標ｘを一定の長さΔｘで離散化した位置パラメータであり、図２に示すように、排気還流通路５の管路長Ｌをｎ分割したとき（Δｘ＝Ｌ／ｎ）、１からｎまでの値をとる。なおλ0（ｉ＝１のときのλi-1）は、排気還流通路５に流入する排気の空気過剰率である。

Figure 2006291871
When equation (1) is converted into a difference equation, the following equation (2) is obtained, and when this is transformed, the following equation (3) is obtained. In Equation (2), k is a calculation time discretized at the calculation cycle Δt, i is a position parameter obtained by discretizing the position coordinate x with a certain length Δx, and as shown in FIG. When the pipe line length L of the passage 5 is divided into n (Δx = L / n), values from 1 to n are taken. Note that λ 0 (λ i-1 when i = 1) is the excess air ratio of the exhaust gas flowing into the exhaust gas recirculation passage 5.
Figure 2006291871

ここで、パラメータａを下記式（４）で定義し、式（３）に適用すると、下記式（５）が得られる。
ａ＝Ｖ・（Δｔ／Δｘ） （４）
λi(k+1)＝（１−ａ）・λi(k)＋ａ・λi-1(k) （５） Here, when the parameter a is defined by the following formula (4) and applied to the formula (3), the following formula (5) is obtained.
a = V · (Δt / Δx) (4)
λ i (k + 1) = (1−a) · λ i (k) + a · λ i−1 (k) (5)

式（５）をｉ＝１〜ｎに対応させて、行列形式で表すと、下記式（６）のようになる。

Figure 2006291871
When the equation (5) is expressed in a matrix form corresponding to i = 1 to n, the following equation (6) is obtained.
Figure 2006291871

図３は、ｎ＝８とした場合において、空気過剰率λ0をステップ状に増加させたときの、空気過剰率λ1〜λ8の推移を示すタイムチャートである。このように、入力側の空気過剰率λ0の変化が、時間遅れを伴って徐々に吸気管側へ伝達される。この例では、吸気管２に流入する排気還流ガスの空気過剰率はλ8で与えられる。 FIG. 3 is a time chart showing the transition of the excess air ratios λ 1 to λ 8 when the excess air ratio λ 0 is increased stepwise when n = 8. Thus, the change in the excess air ratio λ 0 on the input side is gradually transmitted to the intake pipe side with a time delay. In this example, the excess air ratio of the exhaust gas recirculation gas flowing into the intake pipe 2 is given by λ 8 .

図４は、上述した手法により、吸気管２に流入する排気還流ガスの空気過剰率λnを算出する処理のフローチャートである。この処理は、ＥＣＵ２０のＣＰＵで所定時間（例えば３０ミリ秒）毎に実行される。
ステップＳ１１では、酸素濃度センサ２３により検出される酸素濃度ＯＸＣＥに応じて図５に示すλテーブルを検索し、空気過剰率λ0(k)を算出する。 FIG. 4 is a flowchart of a process for calculating the excess air ratio λ n of the exhaust gas recirculation gas flowing into the intake pipe 2 by the method described above. This process is executed every predetermined time (for example, 30 milliseconds) by the CPU of the ECU 20.
In step S11, the λ table shown in FIG. 5 is searched according to the oxygen concentration OXCE detected by the oxygen concentration sensor 23, and the excess air ratio λ 0 (k) is calculated.

ステップＳ１２では、吸入空気流量ＧＡ、エンジン回転数ＮＥ及び吸気圧Ｐ２に応じて排気還流ガス流速Ｖを算出する。具体的には、エンジン回転数ＮＥ及び吸気圧Ｐ２に応じて設定されたＧＣＹＬマップ（図示せず）を検索し、気筒吸入ガス流量ＧＣＹＬを算出し、吸入空気流量ＧＡとともに下記式（７）に適用して、排気還流ガス流量ＧＥＧＲを算出する。
ＧＥＧＲ＝ＧＣＹＬ−ＧＡ （７） In step S12, the exhaust gas recirculation gas flow velocity V is calculated according to the intake air flow rate GA, the engine speed NE, and the intake pressure P2. Specifically, a GCYL map (not shown) set according to the engine speed NE and the intake pressure P2 is searched to calculate the cylinder intake gas flow rate GCYL, and the following equation (7) is calculated together with the intake air flow rate GA. Application is made to calculate the exhaust gas recirculation gas flow rate GEGR.
GEGR = GCYL-GA (7)

排気還流ガス流速Ｖは、排気還流ガス流量ＧＥＧＲに比例する。したがって、所定の換算係数ｋＧＶを排気還流ガス流量ＧＥＧＲに乗算することにより、排気下流ガス流速Ｖが算出される。   The exhaust gas recirculation gas flow velocity V is proportional to the exhaust gas recirculation gas flow rate GEGR. Therefore, the exhaust downstream gas flow velocity V is calculated by multiplying the exhaust gas recirculation gas flow rate GEGR by a predetermined conversion coefficient kGV.

ステップＳ１３では前記式（４）により、パラメータａを算出する。ステップＳ１４では、前記式（６）により、空気過剰率λi（ｉ＝１〜ｎ）を算出し、吸気管２に流入する排気還流ガスの空気過剰率がλnとして算出される。
空気過剰率λnは、図５のλテーブルを逆に参照することにより、排気還流ガス中の酸素濃度ＯＸＣＲに変換することができる。 In step S13, the parameter a is calculated by the equation (4). In step S14, the excess air ratio λ i (i = 1 to n) is calculated from the equation (6), and the excess air ratio of the exhaust gas recirculation gas flowing into the intake pipe 2 is calculated as λ n .
The excess air ratio λ n can be converted to the oxygen concentration OXCR in the exhaust gas recirculation gas by referring to the λ table of FIG. 5 in reverse.

また排気還流ガス流量ＧＥＧＲ及び空気過剰率λnから、排気還流通路５を介して供給される空気流量ＧＡＥＧＲが得られるので、吸入空気量センサ２１により検出される吸入空気流量ＧＡに、空気流量ＧＡＥＧＲを加算することにより、エンジン１の気筒に吸入される気筒吸入空気流量ＧＣＹＬＡが得られる。したがって、気筒吸入空気流量ＧＣＹＬＡに応じて燃料噴射量や燃料噴射時期を決定することにより、正確な燃料供給制御を行うことができる。 Further, since the air flow rate GAEGR supplied through the exhaust gas recirculation passage 5 is obtained from the exhaust gas recirculation gas flow rate GEGR and the excess air ratio λ n , the air flow rate GAEGR is added to the intake air flow rate GA detected by the intake air amount sensor 21. Is added to obtain the cylinder intake air flow rate GCYLA that is taken into the cylinder of the engine 1. Therefore, accurate fuel supply control can be performed by determining the fuel injection amount and the fuel injection timing according to the cylinder intake air flow rate GCYLA.

本実施形態では、排気還流通路５及びＥＧＲ弁６により排気還流手段が構成され、酸素濃度センサ２３により酸素濃度検出手段が構成される。またＥＣＵ２０により、排気還流ガス酸素濃度推定手段が構成される。具体的には、図４に示す処理が排気還流ガス酸素濃度推定手段に相当する。   In this embodiment, the exhaust gas recirculation passage 5 and the EGR valve 6 constitute exhaust gas recirculation means, and the oxygen concentration sensor 23 constitutes oxygen concentration detection means. Further, the ECU 20 constitutes exhaust gas recirculation gas oxygen concentration estimation means. Specifically, the process shown in FIG. 4 corresponds to exhaust gas recirculation gas oxygen concentration estimation means.

なお本発明は上述した実施形態に限るものではなく、種々の変形が可能である。例えば、上述した実施形態では、本発明をディーゼル内燃機関の制御装置に適用したが、本発明はガソリン内燃機関の制御装置にも適用可能である。
また本発明は、クランク軸を鉛直方向とした船外機などのような船舶推進機用エンジンなどの制御にも適用が可能である。 The present invention is not limited to the embodiment described above, and various modifications can be made. For example, in the above-described embodiment, the present invention is applied to a control device for a diesel internal combustion engine, but the present invention is also applicable to a control device for a gasoline internal combustion engine.
The present invention can also be applied to control of a marine vessel propulsion engine such as an outboard motor having a crankshaft as a vertical direction.

本発明の一実施形態にかかる内燃機関及びその制御装置の構成を示す図である。It is a figure which shows the structure of the internal combustion engine and its control apparatus concerning one Embodiment of this invention. モデル化した排気還流通路を示す図である。It is a figure which shows the modeled exhaust gas recirculation passage. 排気還流通路の各分割ブロックにおける空気過剰率の推移を示すタイムチャートである。It is a time chart which shows transition of the excess air ratio in each division block of an exhaust gas recirculation passage. 排気還流ガスの空気過剰率（λ）を算出する処理のフローチャートである。It is a flowchart of the process which calculates the excess air ratio ((lambda)) of exhaust recirculation gas. 酸素濃度（ＯＸＹＣ）から空気過剰率（λ）を算出するためのテーブルを示す図である。It is a figure which shows the table for calculating excess air ratio ((lambda)) from oxygen concentration (OXYC).

符号の説明Explanation of symbols

１ 内燃機関
２ 吸気管
４ 排気管
５ 排気還流通路（排気還流手段）
６ 排気還流弁（排気還流手段）
２０ 電子制御ユニット（排気還流ガス酸素濃度推定手段）
２３ 酸素濃度センサ（酸素濃度検出手段） 1 Internal combustion engine 2 Intake pipe 4 Exhaust pipe 5 Exhaust gas recirculation passage (exhaust gas recirculation means)
6 Exhaust gas recirculation valve (exhaust gas recirculation means)
20 Electronic control unit (exhaust recirculation gas oxygen concentration estimation means)
23 Oxygen concentration sensor (oxygen concentration detection means)

Claims (1)

内燃機関の排気の一部を吸気管に還流する排気還流手段と、排気中の酸素濃度を検出する酸素濃度検出手段とを備えた内燃機関の制御装置において、
前記酸素濃度検出手段の出力及び排気還流ガスの流速を入力とした空気過剰率モデルに基づいて、前記吸気管に流入する排気還流ガス中の酸素濃度を推定する排気還流ガス酸素濃度推定手段を有す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 comprising exhaust gas recirculation means for recirculating a part of exhaust gas of the internal combustion engine to an intake pipe, and oxygen concentration detection means for detecting oxygen concentration in the exhaust gas,
Exhaust gas recirculation gas oxygen concentration estimation means for estimating the oxygen concentration in the exhaust gas recirculation gas flowing into the intake pipe based on the excess air model with the output of the oxygen concentration detection means and the flow velocity of the exhaust gas recirculation gas as inputs A control device for an internal combustion engine.
JP2005114585A 2005-04-12 2005-04-12 Controller of internal combustion engine Pending JP2006291871A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009197801A (en) * 2008-02-19 2009-09-03 Crf Soc Consortile Per Azioni Egr control system
US8001834B2 (en) 2008-06-27 2011-08-23 GM Global Technology Operations LLC Method for detecting faults in the air system of internal combustion engines
JP2012154245A (en) * 2011-01-26 2012-08-16 Denso Corp Control system of internal combustion engine
JP2015063967A (en) * 2013-09-25 2015-04-09 株式会社日本自動車部品総合研究所 Intake air amount estimation device of internal combustion engine

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JPH09287510A (en) * 1996-04-25 1997-11-04 Unisia Jecs Corp Air-fuel ratio controller for internal combustion engine
JP2003222043A (en) * 2002-01-30 2003-08-08 Mazda Motor Corp Engine control unit
JP2005023819A (en) * 2003-07-01 2005-01-27 Mitsubishi Motors Corp Air fuel ratio control system of internal combustion engine

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09287510A (en) * 1996-04-25 1997-11-04 Unisia Jecs Corp Air-fuel ratio controller for internal combustion engine
JP2003222043A (en) * 2002-01-30 2003-08-08 Mazda Motor Corp Engine control unit
JP2005023819A (en) * 2003-07-01 2005-01-27 Mitsubishi Motors Corp Air fuel ratio control system of internal combustion engine

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009197801A (en) * 2008-02-19 2009-09-03 Crf Soc Consortile Per Azioni Egr control system
US8001834B2 (en) 2008-06-27 2011-08-23 GM Global Technology Operations LLC Method for detecting faults in the air system of internal combustion engines
JP2012154245A (en) * 2011-01-26 2012-08-16 Denso Corp Control system of internal combustion engine
JP2015063967A (en) * 2013-09-25 2015-04-09 株式会社日本自動車部品総合研究所 Intake air amount estimation device of internal combustion engine

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