JP2010096001A - Control device - Google Patents

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JP2010096001A
JP2010096001A JP2008264737A JP2008264737A JP2010096001A JP 2010096001 A JP2010096001 A JP 2010096001A JP 2008264737 A JP2008264737 A JP 2008264737A JP 2008264737 A JP2008264737 A JP 2008264737A JP 2010096001 A JP2010096001 A JP 2010096001A
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egr
fuel cut
egr valve
immediately
fuel
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Takahiro Ozaki
貴裕 尾崎
Takahiro Yamanaka
隆弘 山中
Ikuo Ozawa
猪久夫 小澤
Kenji Tanaka
賢治 田中
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Daihatsu Motor Co Ltd
Toyota Motor Corp
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Daihatsu Motor Co Ltd
Toyota Motor Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

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Abstract

<P>PROBLEM TO BE SOLVED: To reduce an error in estimating an EGR rate or an EGR amount immediately after the end of a fuel cut and provide proper control input when controlling an internal combustion engine and an exhaust gas recirculation device affixed to the same. <P>SOLUTION: In a control device performing diagnosis processing involving the forcible opening of an EGR valve during a fuel cut immediately after the end of the fuel cut, a value of the EGR rate or the EGR amount is assumed to be zero and the control input (demanded fuel injection quantity, ignition timing, opening degree of EGR valve and the like) is calculated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、内燃機関及びこれに付帯する排気ガス再循環装置を制御する制御装置に関する。   The present invention relates to an internal combustion engine and a control device that controls an exhaust gas recirculation device incidental thereto.

自動車等の内燃機関では、吸気系と排気系とを排気ガス再循環（Ｅｘｈａｕｓｔ Ｇａｓ Ｒｅｃｉｒｃｕｌａｔｉｏｎ）通路を介して連通し、このＥＧＲ通路を介して排気ガスの一部を吸気系に還流するＥＧＲを行っている。ＥＧＲ通路には、これを開閉するＥＧＲバルブが設けられており、内燃機関の運転状況に応じてＥＧＲバルブの開度を操作し、排気ガスの還流率（または、還流量）や還流時期を制御する。   In an internal combustion engine such as an automobile, an EGR is performed in which an intake system and an exhaust system are connected via an exhaust gas recirculation passage, and a part of the exhaust gas is returned to the intake system via the EGR passage. ing. The EGR passage is provided with an EGR valve that opens and closes the EGR passage, and controls the exhaust gas recirculation rate (or recirculation amount) and recirculation timing by manipulating the opening degree of the EGR valve according to the operating state of the internal combustion engine. To do.

ＥＧＲバルブの故障は、適確なＥＧＲ制御の妨げとなる。よって、通常、ＥＧＲバルブの故障の有無をオンラインで診断し、故障を検出した暁にはその事実を運転者に告知するとともに記憶装置に記録を残すダイアグノーシス機構を実装している。   Failure of the EGR valve prevents proper EGR control. Therefore, a diagnosis mechanism is usually implemented that diagnoses the presence or absence of a failure of the EGR valve online, notifies the driver of the fact when the failure is detected, and leaves a record in the storage device.

ＥＧＲバルブのダイアグノーシスでは、燃料カット中にＥＧＲバルブを開閉操作し、全閉時における吸気管内圧力、所定開度時における吸気管内圧力をそれぞれ計測して、両者の差圧に基づいたＥＧＲバルブの故障判定を行う（例えば、下記特許文献を参照）。
特開平０２−００９９３７号公報 In the diagnosis of the EGR valve, the EGR valve is opened and closed during fuel cut, and the intake pipe pressure when fully closed and the intake pipe pressure at a predetermined opening are measured, respectively. Failure determination is performed (for example, refer to the following patent document).
Japanese Patent Laid-Open No. 02-009937

燃料カット中は燃料を燃焼させないので、ＥＧＲバルブのダイアグノーシスの際にＥＧＲ通路を経由して吸気系に還流する気体は燃焼ガスを含まない新気である。また、燃料カットの終了直後にＥＧＲバルブが開いている場合にも、ＥＧＲ通路を経由して吸気系に還流する気体は燃焼ガスを含まない新気である。   Since the fuel is not burned during the fuel cut, the gas recirculated to the intake system via the EGR passage during the diagnosis of the EGR valve is fresh air containing no combustion gas. Even when the EGR valve is opened immediately after the end of the fuel cut, the gas recirculated to the intake system via the EGR passage is fresh air that does not contain combustion gas.

一方、内燃機関の燃料噴射、点火やＥＧＲ等の制御を司る電子制御装置（Ｅｌｅｃｔｒｏｎｉｃ Ｃｏｎｔｒｏｌ Ｕｎｉｔ）は、ＥＧＲバルブの開度を参照して現在のＥＧＲ率またはＥＧＲ量を推測している。であるから、燃料カットの終了直後にＥＧＲバルブが開いている場合、ＥＣＵでは燃焼ガスが吸気系に還流しているものとして要求燃料噴射量等の制御入力を演算する。つまり、ＥＧＲ率またはＥＧＲ量の見積もりが実態から乖離してしまうので、最適な制御入力を算定できず、燃料噴射量が不足したオーバーリーンとなって、一時的に排気ガスの悪化やエンジン出力の低下（加速の緩慢化）等を招くことがあった。   On the other hand, an electronic control unit (Electronic Control Unit) that controls the fuel injection, ignition, EGR, and the like of the internal combustion engine estimates the current EGR rate or EGR amount by referring to the opening of the EGR valve. Therefore, when the EGR valve is opened immediately after the end of the fuel cut, the ECU calculates a control input such as a required fuel injection amount on the assumption that the combustion gas is recirculated to the intake system. In other words, since the estimation of the EGR rate or EGR amount deviates from the actual situation, the optimal control input cannot be calculated, the fuel injection amount becomes insufficient, and the exhaust gas is temporarily deteriorated or the engine output is temporarily reduced. Decrease (slow acceleration) may occur.

本発明は、以上の問題に初めて着目してなされたもので、燃料カットの終了直後におけるＥＧＲ率またはＥＧＲ量の推測の誤りを低減し、以て制御入力の適正化を図ることを所期の目的としている。   The present invention has been made by paying attention to the above problems for the first time, and it is intended to reduce the error in estimating the EGR rate or the EGR amount immediately after the end of the fuel cut and thereby optimize the control input. It is aimed.

本発明では、内燃機関またはこれに付帯する排気ガス再循環装置を制御する制御装置であり、燃料カット中にＥＧＲバルブの強制開弁を伴うダイアグノーシス処理を実施するものにおいて、燃料カットの終了直後にはＥＧＲ率またはＥＧＲ量の値を０と見なして内燃機関または排気ガス再循環装置の制御を行うこととした。即ち、燃料カットの終了直後にはＥＧＲ率またはＥＧＲ量の値を０と見なして制御入力の演算を行うようにした。本発明によれば、ＥＧＲ率またはＥＧＲ量の見積もりが実態から乖離してしまう問題を回避でき、排気ガスの悪化やエンジン出力の低下等の不具合を抑制することが可能になる。   In the present invention, a control device for controlling an internal combustion engine or an exhaust gas recirculation device incidental thereto, which performs a diagnosis process involving forced opening of an EGR valve during a fuel cut, immediately after the end of the fuel cut Therefore, the internal combustion engine or the exhaust gas recirculation device is controlled by regarding the value of the EGR rate or EGR amount as 0. That is, immediately after the end of the fuel cut, the control input is calculated by regarding the value of the EGR rate or EGR amount as 0. According to the present invention, it is possible to avoid the problem that the estimation of the EGR rate or the EGR amount deviates from the actual situation, and it is possible to suppress problems such as deterioration of exhaust gas and reduction of engine output.

加えて、燃料カットの終了直後には、たとえＥＧＲ率またはＥＧＲ量の目標値が０でなくＥＧＲバルブを開けておくべきであるとしても、敢えて一旦ＥＧＲバルブを全閉に操作することが好ましい。強制的にＥＧＲバルブを閉じた後、再びＥＧＲバルブを開いたときにＥＧＲ通路を還流する気体は燃焼ガスである見込みが高い。従って、上記のバルブ操作により、ＥＧＲバルブの開度に基づくＥＧＲ率またはＥＧＲ量の推測の正確性が増す。   In addition, immediately after the end of the fuel cut, even if the target value of the EGR rate or EGR amount is not 0 and the EGR valve should be opened, it is preferable to darely operate the EGR valve once. After forcibly closing the EGR valve, the gas that recirculates in the EGR passage when the EGR valve is opened again is likely to be combustion gas. Therefore, the above-described valve operation increases the accuracy of estimating the EGR rate or the EGR amount based on the opening degree of the EGR valve.

また、燃料カット開始直後からＥＧＲバルブのダイアグノーシス処理を実施すると、ダイアグノーシスを始めてすぐに燃料カットが終了した場合にＥＧＲ通路を還流する気体には燃焼ガスが含まれる可能性がある。既に述べた通り、本発明に係る制御装置では、燃料カット終了直後におけるＥＧＲ率またはＥＧＲ量を０と見なすので、燃料カット終了直後に吸気系に還流する気体が新気と燃焼ガスとの混合であると都合が悪い。実際には燃焼ガスが還流しているにもかかわらず、新気のみがシリンダに流入するものとして制御入力を演算してしまえば、燃料噴射量が過剰なオーバーリッチとなり、やはり排気ガスの悪化等を招いてしまう。これに対し、燃焼カットの開始から所定時間が経過しかつ依然として燃料カット中であることを条件としてＥＧＲバルブのダイアグノーシス処理を開始するようにすれば、シリンダ及び排気マニホルド内から燃焼ガスが充分に抜けたと考えられる時期からＥＧＲバルブの開弁を実行することとなるので、ＥＧＲ通路を還流する気体はほぼ新気であることが保証される。   Further, if the diagnosis process of the EGR valve is performed immediately after the start of the fuel cut, the gas that recirculates through the EGR passage when the fuel cut ends immediately after the start of the diagnosis may include a combustion gas. As already described, in the control device according to the present invention, the EGR rate or EGR amount immediately after the end of the fuel cut is regarded as 0, so that the gas recirculated to the intake system immediately after the end of the fuel cut is a mixture of fresh air and combustion gas. It is inconvenient if there is. If the control input is calculated on the assumption that only fresh air flows into the cylinder even though the combustion gas is actually recirculating, the fuel injection amount will be excessively rich, and the exhaust gas will deteriorate. Will be invited. On the other hand, if the diagnosis process of the EGR valve is started on the condition that a predetermined time has elapsed from the start of the combustion cut and the fuel is still being cut, the combustion gas is sufficiently discharged from the cylinder and the exhaust manifold. Since the opening of the EGR valve is executed from the time when it is considered that the gas has escaped, it is guaranteed that the gas recirculating through the EGR passage is almost fresh.

本発明によれば、燃料カットの終了直後におけるＥＧＲ率またはＥＧＲ量の推測の誤りを低減でき、制御入力の適正化を図り得る。   According to the present invention, an error in estimating the EGR rate or the EGR amount immediately after the end of the fuel cut can be reduced, and the control input can be optimized.

以下、本発明の一実施形態を、図面を参照して説明する。図１に１気筒の構成を概略的に示した内燃機関１００は、例えば自動車に搭載されるものである。内燃機関１００の吸気系１には、アクセルペダル（図示せず）の踏込量に応じて開閉するスロットルバルブ１１を設けており、スロットルバルブ１１の下流にはサージタンク１３を一体に有する吸気マニホルド１２を取り付けている。シリンダ２上部に形成される燃焼室２１の天井部には点火プラグ８を、吸気マニホルド１２の吸気ポート側端部には燃料噴射弁３を、それぞれ設けている。   Hereinafter, an embodiment of the present invention will be described with reference to the drawings. An internal combustion engine 100 schematically showing the configuration of one cylinder in FIG. 1 is mounted on, for example, an automobile. The intake system 1 of the internal combustion engine 100 is provided with a throttle valve 11 that opens and closes according to the amount of depression of an accelerator pedal (not shown), and an intake manifold 12 that integrally has a surge tank 13 downstream of the throttle valve 11. Is attached. A spark plug 8 is provided at the ceiling of the combustion chamber 21 formed in the upper part of the cylinder 2, and a fuel injection valve 3 is provided at the end of the intake manifold 12 on the intake port side.

内燃機関１００の排気系５には、排気マニホルド５１を取り付け、その下流に三元触媒５２を装着している。そして、吸気系１と排気系５との間を、排気ガス再循環装置６を介して接続している。   An exhaust manifold 51 is attached to the exhaust system 5 of the internal combustion engine 100, and a three-way catalyst 52 is attached downstream thereof. The intake system 1 and the exhaust system 5 are connected via an exhaust gas recirculation device 6.

排気ガス再循環装置６は、始端が排気マニホルド５１に連通し終端がサージタンク１３に連通するＥＧＲ通路６１と、ＥＧＲ通路６１上に設けた外部ＥＧＲバルブ６２とを要素とする。ＥＧＲバルブ６２は、その開度操作を通じてＥＧＲ通路６１を還流する排気ガス（ＥＧＲガス）の流量を制御する。   The exhaust gas recirculation device 6 includes an EGR passage 61 having a start end communicating with the exhaust manifold 51 and a terminal end communicating with the surge tank 13, and an external EGR valve 62 provided on the EGR passage 61. The EGR valve 62 controls the flow rate of exhaust gas (EGR gas) that recirculates through the EGR passage 61 through its opening operation.

内燃機関１００及び排気ガス再循環装置６の制御を司る制御装置は、ＥＣＵ４を主体とする。ＥＣＵ４は、中央演算装置４１、記憶装置４２、入力インタフェース４３、出力インタフェース４４等を有するマイクロコンピュータシステムである。入力インタフェース４３には、吸気負圧を検出する圧力センサ７１から出力される吸気負圧信号ａ、エンジン回転数を検出する回転数センサ７２から出力される回転数信号ｂ、車速を検出する車速センサ７３から出力される車速信号ｃ、アイドルスイッチ７４から出力されるＩＤＬ信号ｄ、冷却水温度を検出する水温センサ７６から出力される水温信号ｆ、燃焼圧の変化によりノッキングの状態を検出するノッキングセンサ７５から出力されるノッキング信号ｅ等が入力される。出力インタフェース４４からは、燃料噴射弁３に対して燃料噴射信号ｎ、点火プラグ８に対して点火信号ｍ、ＥＧＲバルブ６２に対してバルブ開度信号ｏ等を出力する。   The control device that controls the internal combustion engine 100 and the exhaust gas recirculation device 6 is mainly composed of the ECU 4. The ECU 4 is a microcomputer system having a central processing unit 41, a storage device 42, an input interface 43, an output interface 44, and the like. The input interface 43 includes an intake negative pressure signal a output from a pressure sensor 71 that detects intake negative pressure, a rotation speed signal b output from a rotation speed sensor 72 that detects engine rotation speed, and a vehicle speed sensor that detects vehicle speed. 73, a vehicle speed signal c output from the idle switch 74, an IDL signal d output from the idle switch 74, a water temperature signal f output from the water temperature sensor 76 for detecting the cooling water temperature, and a knocking sensor for detecting the knocking state by a change in the combustion pressure. The knocking signal e output from 75 is input. From the output interface 44, a fuel injection signal n is output to the fuel injection valve 3, an ignition signal m is output to the spark plug 8, a valve opening signal o is output to the EGR valve 62, and the like.

中央演算装置４１は、予め記憶装置４２に格納されているプログラムを解釈、実行し、以て内燃機関１００の運転を制御する。即ち、内燃機関１００の運転制御に必要な各種情報ａ、ｂ、ｃ、ｄ、ｅ、ｆを入力インタフェース４３を介して取得し、それらに基づいて制御入力である燃料噴射量、点火時期、ＥＧＲバルブ６２の開度等を算出して、制御入力に対応した制御信号ｍ、ｎ、ｏを出力インタフェース４４を介して印加する。   The central processing unit 41 interprets and executes a program stored in advance in the storage device 42, thereby controlling the operation of the internal combustion engine 100. That is, various types of information a, b, c, d, e, and f necessary for operation control of the internal combustion engine 100 are acquired via the input interface 43, and based on them, the fuel injection amount, ignition timing, EGR, which are control inputs. The opening degree of the valve 62 is calculated, and control signals m, n, and o corresponding to the control input are applied via the output interface 44.

ＥＣＵ４は、圧力センサ７１から出力される吸気負圧信号ａ、回転数センサ７２から出力される回転数信号ｂ、ＥＧＲバルブ６２の開度等を参照し、新気量及びＥＧＲ率（または、ＥＧＲ量）を推測する。さらに、水温センサ７６から出力される水温信号ｆ等を参照して、要求される燃料噴射量いわばエンジン負荷を演算する。その上で、要求燃料噴射量に相当する燃料噴射時間（燃料噴射弁３に対する通電時間）だけ燃料噴射弁３に信号ｎを入力、吸気系１に燃料を噴射させる。   The ECU 4 refers to the intake negative pressure signal a output from the pressure sensor 71, the rotation speed signal b output from the rotation speed sensor 72, the opening degree of the EGR valve 62, and the like, and the fresh air amount and the EGR rate (or EGR rate (or EGR) Guess). Further, referring to the water temperature signal f output from the water temperature sensor 76, the required fuel injection amount, that is, the engine load is calculated. After that, the signal n is input to the fuel injection valve 3 for the fuel injection time corresponding to the required fuel injection amount (energization time for the fuel injection valve 3), and fuel is injected into the intake system 1.

加えて、ＥＣＵ４は、内燃機関１００の運転状況に応じた目標ＥＧＲ率を達成するのに必要なＥＧＲバルブ６２の開度を演算し、開度信号ｏをＥＧＲバルブ６２に入力、ＥＧＲバルブ６２を操作する。   In addition, the ECU 4 calculates the opening degree of the EGR valve 62 necessary to achieve the target EGR rate corresponding to the operating state of the internal combustion engine 100, inputs the opening degree signal o to the EGR valve 62, and sets the EGR valve 62 to the EGR valve 62. Manipulate.

また、ＥＣＵ４は、ノッキングセンサ７５から出力されるノッキング信号ｅをも参照して、内燃機関１００の運転状況及びノッキング状態に応じた点火時期（遅角量または進角量）を演算し、その点火時期に点火プラグ８に信号ｍを入力、シリンダ２内の混合気への点火を行う。   The ECU 4 also refers to the knocking signal e output from the knocking sensor 75 to calculate the ignition timing (retard amount or advance amount) according to the operating state and knocking state of the internal combustion engine 100, and the ignition The signal m is input to the spark plug 8 at the timing, and the mixture in the cylinder 2 is ignited.

しかして、本実施形態では、燃料噴射を行わない燃料カット中に、ＥＧＲバルブ６２のダイアグノーシス処理を実施するものとしている。燃料カットは、例えばエンジン回転数が一定以上あり、アイドルスイッチ７４がＯＮになったときに開始する。ＥＧＲダイアグノーシスでは、燃料カットの開始後にＥＧＲバルブ６２を開閉操作して、全閉時における吸気管内圧力、所定開度時における吸気管内圧力をそれぞれ計測し、両者の差圧に基づいたＥＧＲバルブ６２の故障判定を行う。   Therefore, in the present embodiment, the diagnosis process of the EGR valve 62 is performed during the fuel cut in which fuel injection is not performed. The fuel cut is started when, for example, the engine speed is a certain level or more and the idle switch 74 is turned on. In the EGR diagnosis, the EGR valve 62 is opened and closed after the fuel cut is started, and the intake pipe internal pressure when fully closed and the intake pipe internal pressure when a predetermined opening degree is measured, respectively, and the EGR valve 62 based on the differential pressure between the two. Perform a failure judgment.

燃料カットは、エンジン回転数が所定の復帰回転数以下まで下がったとき、あるいはアイドルスイッチ７４がＯＦＦになったときに終了する。故に、ＥＧＲダイアグノーシスの最中に燃料カットの終了条件が成立してしまうこともあり得る。例えば、急ブレーキが踏まれた場合やマニュアルトランスミッション車においてクラッチが切られた場合にはエンジン回転数が急落し、ＥＧＲダイアグノーシスの完了以前に燃料カットが終了してしまう。無論、アクセルが踏まれた場合も同様である。   The fuel cut ends when the engine speed falls below a predetermined return speed or when the idle switch 74 is turned off. Therefore, the fuel cut end condition may be satisfied during the EGR diagnosis. For example, when sudden braking is applied or when the clutch is disengaged in a manual transmission vehicle, the engine speed drops sharply and fuel cut ends before EGR diagnosis is completed. Of course, the same applies when the accelerator is depressed.

ＥＧＲダイアグノーシスの完了以前に燃料カットが終了した場合には、燃料カット終了直後の時点で既にＥＧＲバルブ６２が開弁している状態となる。ＥＧＲダイアグノーシスの完了以後に燃料カットが終了した場合でも、燃料カット終了直後の時点で目標ＥＧＲ率が０でなければ、燃料カット終了直後からＥＧＲバルブ６２が開弁することになる。その際に、ＥＧＲ通路６１を経由して吸気系１に還流する気体は、殆どまたは全く燃焼ガスを含まない新気である。   When the fuel cut is completed before the completion of the EGR diagnosis, the EGR valve 62 is already opened immediately after the fuel cut is completed. Even if the fuel cut ends after completion of the EGR diagnosis, if the target EGR rate is not 0 immediately after the fuel cut ends, the EGR valve 62 opens immediately after the fuel cut ends. At that time, the gas recirculated to the intake system 1 via the EGR passage 61 is fresh air containing little or no combustion gas.

ところが、ＥＣＵ４はＥＧＲバルブ６２の開度を参照して現在のＥＧＲ率を推測し、要求燃料噴射量等の制御入力を演算している。であるから、実際には燃焼ガスは吸気系１に還流していないにもかかわらず、燃料ガスの還流を加味した燃料噴射量等を算出してしまいかねない。さすれば、燃料噴射量が不足したオーバーリーンとなってしまう。そこで、燃料カットの終了直後においては、ＥＧＲバルブ６２の開度によらずＥＧＲ率の値を０と見なして、制御入力を演算する。   However, the ECU 4 estimates the current EGR rate with reference to the opening degree of the EGR valve 62, and calculates a control input such as a required fuel injection amount. Therefore, although the combustion gas does not actually recirculate to the intake system 1, the fuel injection amount and the like taking into account the recirculation of the fuel gas may be calculated. If so, the fuel injection amount becomes insufficient. Therefore, immediately after the end of the fuel cut, the control input is calculated by regarding the value of the EGR rate as 0 regardless of the opening degree of the EGR valve 62.

また、ＥＧＲダイアグノーシスの完了以前に燃料カットが終了し、しかも燃料カット終了直後の時点で目標ＥＧＲ率が０でないような場合、理屈の上では（即ち、ＥＧＲのサーボ制御上は）燃料カット終了前後を跨いでＥＧＲバルブ６２を開け続けることになる。換言すれば、燃料カット終了直後にＥＧＲバルブ６２を全閉する必要はないのであるが、本実施形態では、燃料カット終了とともに敢えて一旦ＥＧＲバルブ６２を全閉し、しかる後に再度目標ＥＧＲ率を達成するべくＥＧＲバルブ６２の開度操作を行う。これもまた、ＥＧＲバルブ６２の開度に基づいたＥＧＲ率の推測値と実態との乖離を避ける趣旨である。   Also, if the fuel cut ends before the completion of EGR diagnosis and the target EGR rate is not 0 immediately after the fuel cut ends, the fuel cut ends theoretically (that is, for EGR servo control). The EGR valve 62 is kept open across the front and rear. In other words, it is not necessary to fully close the EGR valve 62 immediately after the end of the fuel cut. In this embodiment, however, the EGR valve 62 is once fully closed when the fuel cut ends, and then the target EGR rate is achieved again. The opening operation of the EGR valve 62 is performed as much as possible. This is also intended to avoid a difference between the estimated value of the EGR rate based on the opening degree of the EGR valve 62 and the actual state.

なお、ＥＧＲダイアグノーシスは、燃料カット開始条件が成立してもすぐには始めない。先の議論とは逆に、燃料カット開始から即座にＥＧＲダイアグノーシスを実施し、その後間もなくして燃料カットが終了した場合には、ＥＧＲ通路６１を還流する気体に燃焼ガスが含まれる可能性がある。本実施形態では、燃料カットの終了直後におけるＥＧＲ率の値を０と見なすので、燃料カット終了直後に吸気系１に還流する気体が新気と燃焼ガスとの混合であると都合が悪い。実際には燃焼ガスが還流しているにもかかわらず、新気のみがシリンダ２に流入するものとして燃料噴射量等を演算してしまえば、燃料噴射量が過剰なオーバーリッチとなってしまう。そのため、本実施形態では、燃焼カットの開始から所定時間が経過し、かつ依然として燃料カット中であることを条件として、ＥＧＲダイアグノーシスを開始する。   Note that EGR diagnosis does not start immediately even if the fuel cut start condition is satisfied. Contrary to the previous discussion, when the EGR diagnosis is performed immediately after the start of the fuel cut and the fuel cut is completed shortly thereafter, there is a possibility that combustion gas is included in the gas recirculating through the EGR passage 61. is there. In the present embodiment, since the value of the EGR rate immediately after the end of the fuel cut is regarded as 0, it is not convenient if the gas recirculated to the intake system 1 immediately after the end of the fuel cut is a mixture of fresh air and combustion gas. If the fuel injection amount is calculated assuming that only fresh air flows into the cylinder 2 in spite of the fact that the combustion gas is recirculating, the fuel injection amount becomes excessively rich. Therefore, in this embodiment, EGR diagnosis is started on the condition that a predetermined time has elapsed from the start of the combustion cut and the fuel is still being cut.

本実施形態の制御装置が実行する処理手順を、図２及び図３を参照して補足する。ＥＣＵ４は、燃料カット開始条件が成立した場合（ステップＳ１）、経過時間の計数を開始し（ステップＳ２）、その経過時間が所定値、例えば１秒に達したときに（ステップＳ３）ＥＧＲバルブ６２のダイアグノーシス処理を開始する（ステップＳ５）。但し、それ以前に燃料カット終了条件が成立した場合には（ステップＳ４）この限りではない。   A processing procedure executed by the control device of the present embodiment will be supplemented with reference to FIGS. 2 and 3. When the fuel cut start condition is satisfied (step S1), the ECU 4 starts counting elapsed time (step S2), and when the elapsed time reaches a predetermined value, for example, 1 second (step S3), the EGR valve 62 The diagnosis process is started (step S5). However, this is not the case when the fuel cut end condition is satisfied before that (step S4).

そして、燃料カット中において、燃料カット終了条件が成立した場合には（ステップＳ６）、制御入力の演算に用いられるＥＧＲ率の推測値をＥＧＲバルブ６２の開度によらず０と見なす（ステップＳ７）。並びに、ＥＧＲバルブ６２を強制的に全閉操作する（ステップＳ８）。ＥＧＲバルブ６２の開度が全閉となったら（ステップＳ９）、平常通り目標ＥＧＲ率に従うＥＧＲバルブ６２の開度操作を再開する（ステップＳ１０）とともに、ＥＧＲバルブ６２の開度に基づくＥＧＲ率の推測を再開する（ステップＳ１１）。   When the fuel cut end condition is satisfied during the fuel cut (step S6), the estimated value of the EGR rate used for the calculation of the control input is regarded as 0 regardless of the opening degree of the EGR valve 62 (step S7). ). At the same time, the EGR valve 62 is forcibly fully closed (step S8). When the opening of the EGR valve 62 is fully closed (step S9), the opening operation of the EGR valve 62 according to the target EGR rate is resumed as usual (step S10), and the EGR rate based on the opening of the EGR valve 62 is changed. The estimation is resumed (step S11).

本実施形態によれば、内燃機関１００またはこれに付帯する排気ガス再循環装置６を制御する制御装置４であり、燃料カット中にＥＧＲバルブ６２の強制開弁を伴うダイアグノーシス処理を実施するものにおいて、燃料カットの終了直後にはＥＧＲ率またはＥＧＲ量の値を０と見なして内燃機関１００または排気ガス再循環装置６の制御を行う、即ち要求燃料噴射量、点火時期、ＥＧＲバルブ６２開度等の制御入力を算定することとしたため、ＥＧＲ率またはＥＧＲ量の見積もりが実態から乖離してしまう問題を回避でき、排気ガスの悪化やエンジン出力の低下等の不具合を抑制することが可能になる。   According to the present embodiment, the control device 4 controls the internal combustion engine 100 or the exhaust gas recirculation device 6 incidental thereto, and performs a diagnosis process involving forced opening of the EGR valve 62 during fuel cut. Immediately after the end of the fuel cut, the internal combustion engine 100 or the exhaust gas recirculation device 6 is controlled by assuming that the value of the EGR rate or EGR amount is 0, that is, the required fuel injection amount, ignition timing, EGR valve 62 opening degree. Therefore, it is possible to avoid the problem that the estimation of the EGR rate or the amount of EGR deviates from the actual situation, and it is possible to suppress problems such as deterioration of exhaust gas and reduction of engine output. .

加えて、燃料カットの終了直後には、たとえＥＧＲ率またはＥＧＲ量の目標値が０でなくＥＧＲバルブ６２を開けておくべきであるとしても、敢えて一旦ＥＧＲバルブ６２を全閉に操作する。これにより、ＥＧＲバルブ６２の開度に基づくＥＧＲ率またはＥＧＲ量の推測の正確性が増す。   In addition, immediately after the end of the fuel cut, even if the target value of the EGR rate or EGR amount is not 0 and the EGR valve 62 should be opened, the EGR valve 62 is once fully closed. Thereby, the accuracy of the estimation of the EGR rate or the EGR amount based on the opening degree of the EGR valve 62 is increased.

また、燃焼カットの開始から所定時間が経過しかつ依然として燃料カット中であることを条件としてＥＧＲバルブ６２のダイアグノーシス処理を開始するようにしているため、シリンダ２及び排気マニホルド５１内から燃焼ガスが充分に抜けたと考えられる時期からＥＧＲバルブ６２の開弁を実行することとなるので、ＥＧＲ通路６１を還流する気体はほぼ新気であることが保証される。   Further, since the diagnosis process of the EGR valve 62 is started on the condition that a predetermined time has elapsed from the start of the combustion cut and the fuel is still being cut, the combustion gas is discharged from the cylinder 2 and the exhaust manifold 51. Since the EGR valve 62 is opened from the time when it is considered that the gas has been sufficiently removed, it is guaranteed that the gas recirculating through the EGR passage 61 is almost fresh.

なお、本発明は以上に詳述した実施形態に限られるものではない。例えば、上記実施形態における内燃機関は火花点火エンジンであったが、これがディーゼルエンジンであっても構わない。   The present invention is not limited to the embodiment described in detail above. For example, the internal combustion engine in the above embodiment is a spark ignition engine, but it may be a diesel engine.

その他各部の具体的構成は、本発明の趣旨を逸脱しない範囲で種々変形が可能である。   Other specific configurations of each part can be variously modified without departing from the spirit of the present invention.

本発明の一実施形態における内燃機関、排気ガス再循環装置及び制御装置の概略構成を示す図。The figure which shows schematic structure of the internal combustion engine, exhaust-gas recirculation apparatus, and control apparatus in one Embodiment of this invention. 同実施形態の制御装置が実行する処理手順を示すフロー図。The flowchart which shows the process sequence which the control apparatus of the embodiment performs. 同実施形態の制御装置が実行する処理手順を示すフロー図。The flowchart which shows the process sequence which the control apparatus of the embodiment performs.

符号の説明Explanation of symbols

０…内燃機関
４…ＥＣＵ（制御装置）
６…排気ガス再循環装置
６２…ＥＧＲバルブ 0 ... Internal combustion engine 4 ... ECU (control device)
6 ... Exhaust gas recirculation device 62 ... EGR valve

Claims (3)

内燃機関またはこれに付帯する排気ガス再循環（Ｅｘｈａｕｓｔ Ｇａｓ Ｒｅｃｉｒｃｕｌａｔｉｏｎ）装置を制御する制御装置であり、燃料カット中にＥＧＲバルブの強制開弁を伴うダイアグノーシス処理を実施するものにおいて、
燃料カットの終了直後にはＥＧＲ率またはＥＧＲ量の値を０と見なして内燃機関または排気ガス再循環装置の制御を行うことを特徴とする制御装置。 A control device that controls an internal combustion engine or an exhaust gas recirculation device that accompanies the internal combustion engine, and that performs a diagnosis process that involves forcibly opening an EGR valve during fuel cut,
Immediately after the end of the fuel cut, the control device controls the internal combustion engine or the exhaust gas recirculation device by regarding the value of the EGR rate or EGR amount as 0. 燃料カットの終了直後に一旦ＥＧＲバルブを全閉に操作する請求項１記載の制御装置。 The control device according to claim 1, wherein the EGR valve is once fully closed immediately after the end of the fuel cut. 燃焼カットの開始から所定時間が経過しかつ依然として燃料カット中であることを条件としてダイアグノーシス処理を開始する請求項１または２記載の制御装置。 The control device according to claim 1 or 2, wherein the diagnosis process is started on the condition that a predetermined time has elapsed from the start of the combustion cut and the fuel is still being cut.
JP2008264737A 2008-10-14 2008-10-14 Control device Pending JP2010096001A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021199411A1 (en) * 2020-04-02 2021-10-07 日産自動車株式会社 Egr estimation method for internal combustion engine, and egr estimation device for internal combustion engine
JPWO2021199411A1 (en) * 2020-04-02 2021-10-07
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