JP2002013431A - Catalyst early warming controller of cylinder injection internal combustion engine - Google Patents
Catalyst early warming controller of cylinder injection internal combustion engineInfo
- Publication number
- JP2002013431A JP2002013431A JP2000201427A JP2000201427A JP2002013431A JP 2002013431 A JP2002013431 A JP 2002013431A JP 2000201427 A JP2000201427 A JP 2000201427A JP 2000201427 A JP2000201427 A JP 2000201427A JP 2002013431 A JP2002013431 A JP 2002013431A
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- Prior art keywords
- injection
- post
- catalyst
- combustion mode
- switching
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- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、筒内噴射式内燃機
関において、排出ガス浄化用の触媒を早期に暖機する機
能を備えた筒内噴射式内燃機関の触媒早期暖機制御装置
に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for early warming-up of a direct injection internal combustion engine having a function of early warming up a catalyst for purifying exhaust gas in a direct injection internal combustion engine. It is.
【０００２】[0002]
【従来の技術】筒内噴射式内燃機関（直噴エンジン）に
おいても、排出ガスの浄化は、吸気管噴射エンジンと同
様に、触媒によって行うようにしているが、触媒は、活
性温度まで昇温しないと、排出ガスを効率良く浄化でき
ないため、始動後に排気温度を上昇させて触媒を早期に
活性温度まで昇温させる触媒早期暖機制御を行うことが
望ましい。吸気管噴射エンジンでは、触媒早期暖機制御
を点火遅角制御等によって行われているが、直噴エンジ
ンでは、特開平４−１８３９２２号公報に示すように、
排気管の触媒の上流側に点火装置を設け、触媒の温度が
所定温度より低い時に、膨張行程又は排気行程で追加の
燃料を噴射して排出ガス中に燃料を混入させ、これを排
気管内で点火装置によって着火して燃焼させることで、
排気温度を上昇させて触媒を暖機するようにしたものが
ある。2. Description of the Related Art In a direct injection internal combustion engine (a direct injection engine), purification of exhaust gas is performed by a catalyst, similarly to an intake pipe injection engine, but the temperature of the catalyst is raised to an activation temperature. Otherwise, the exhaust gas cannot be efficiently purified. Therefore, it is desirable to perform catalyst early warm-up control in which the exhaust gas temperature is raised after the start and the temperature of the catalyst is quickly raised to the activation temperature. In the intake pipe injection engine, the catalyst early warm-up control is performed by ignition retard control and the like. In the direct injection engine, as shown in Japanese Patent Application Laid-Open No. 4-183922,
An ignition device is provided upstream of the catalyst in the exhaust pipe, and when the temperature of the catalyst is lower than a predetermined temperature, additional fuel is injected in an expansion stroke or an exhaust stroke to mix fuel into exhaust gas, and this is injected into the exhaust pipe. By igniting and burning by the ignition device,
In some cases, the catalyst is warmed up by raising the exhaust gas temperature.
【０００３】しかし、この構成では、排気管に点火装置
を設ける必要があり、その分、コスト高になる欠点があ
る。[0003] However, in this configuration, it is necessary to provide an ignition device in the exhaust pipe, and there is a disadvantage that the cost increases accordingly.
【０００４】この欠点を解消するため、特開平８−２９
１７２９号公報に示すように、圧縮行程でエンジン出力
を発生させるための主噴射を行った後に膨張行程で後噴
射を行って、主噴射燃料の燃焼熱によって後噴射燃料を
燃焼させることで、排気温度を上昇させて触媒の暖機を
促進するようにしたものがある。[0004] To solve this drawback, Japanese Patent Application Laid-Open No. 8-29 is disclosed.
As disclosed in Japanese Patent No. 1729, by performing main injection for generating an engine output in a compression stroke and then performing post-injection in an expansion stroke and burning the post-injection fuel by the heat of combustion of the main injection fuel, exhaust gas is emitted. In some cases, the temperature is increased to promote warm-up of the catalyst.
【０００５】[0005]
【発明が解決しようとする課題】直噴エンジンでも、始
動時は燃圧が低く、更に要求噴射量が多いため、吸気行
程で燃料を噴射して均質燃焼させるようにしている。従
って、始動時は、触媒が未活性でも、均質燃焼モードで
運転し、始動後、成層燃焼が可能な運転状態になった時
に、圧縮行程で燃料を噴射して成層燃焼させる成層燃焼
モードに切り換えて、上記公報のように、膨張行程で後
噴射を行って触媒を暖機するようにしたものがある。Even in a direct injection engine, the fuel pressure is low at the time of starting and the required injection amount is large, so that the fuel is injected during the intake stroke to perform homogeneous combustion. Therefore, at the time of starting, the engine is operated in the homogeneous combustion mode even if the catalyst is inactive, and after the engine is started, when the operating state allows stratified combustion, the mode is switched to the stratified combustion mode in which fuel is injected in the compression stroke to perform stratified combustion. As described in the above publication, there is an apparatus in which post-injection is performed in the expansion stroke to warm up the catalyst.
【０００６】しかし、均質燃焼モードから成層燃焼モー
ドへ切り換える際に、スロットルバルブ等の空気系を大
きく切り換えるため、その空気系の切り換えに、かなり
の遅れが生じる。つまり、均質燃焼モードから成層燃焼
モードに切り換えてから、筒内に充填される空気量が目
標値まで増加するのに、かなりの遅れが生じる。このた
め、成層燃焼モードに切り換わった直後から、後噴射を
通常の成層燃焼時の後噴射量で開始すると、筒内の空気
量（酸素量）が不足して後噴射の燃料を十分に燃焼させ
ることができず、排気エミッションが悪化する結果とな
る。[0006] However, when switching from the homogeneous combustion mode to the stratified combustion mode, the air system such as the throttle valve is largely switched, so that the switching of the air system is considerably delayed. That is, after switching from the homogeneous combustion mode to the stratified combustion mode, a considerable delay occurs after the amount of air charged into the cylinder increases to the target value. Therefore, immediately after switching to the stratified combustion mode, if the post-injection is started at the post-injection amount during normal stratified combustion, the amount of air (oxygen amount) in the cylinder becomes insufficient and the fuel of the post-injection is sufficiently burned. And exhaust emissions are worsened.
【０００７】そこで、後噴射の開始時期を空気系の遅れ
分だけ遅らせることが考えられるが、成層燃焼モードで
は、多量の空気を筒内に吸入して排出するため、後噴射
の開始時期（排気温度の昇温開始時期）を遅らせると、
成層燃焼モードへの切換直後に急増する空気によって排
気温度が低下して触媒が冷やされてしまい、触媒の暖機
が益々遅れて、排気エミッションが悪化する結果とな
る。Therefore, it is conceivable to delay the start timing of the post-injection by the delay of the air system. However, in the stratified combustion mode, a large amount of air is sucked into the cylinder and discharged. When the temperature rise starts),
Sudden increase in air immediately after switching to the stratified combustion mode lowers the exhaust gas temperature and cools down the catalyst, which further delays warming up of the catalyst and results in deterioration of exhaust emission.
【０００８】また、始動直後は、筒内温度が低いため、
主噴射燃料の燃焼熱で後噴射燃料を着火可能な期間が短
くなる。このため、成層燃焼モードへの切換直後から、
後噴射を通常の成層燃焼時の後噴射時期で開始すると、
後噴射の燃料を主噴射燃料の燃焼熱で着火できない可能
性がある。[0008] Immediately after starting, the temperature in the cylinder is low.
The period during which the post-injection fuel can be ignited by the combustion heat of the main injection fuel is shortened. Therefore, immediately after switching to the stratified combustion mode,
If the post-injection is started at the post-injection timing during normal stratified combustion,
There is a possibility that the post-injection fuel cannot be ignited by the combustion heat of the main injection fuel.
【０００９】本発明はこのような事情を考慮してなされ
たものであり、従ってその目的は、成層燃焼モードへの
切換直後から後噴射を開始しても、後噴射の燃料を十分
に燃焼させることができて、触媒早期暖機性能向上、排
気エミッション低減を実現することができる筒内噴射式
内燃機関の触媒早期暖機制御装置を提供することにあ
る。The present invention has been made in view of such circumstances, and the object thereof is to sufficiently burn the post-injection fuel even if the post-injection is started immediately after switching to the stratified combustion mode. It is an object of the present invention to provide a catalyst early warming-up control device for an in-cylinder injection type internal combustion engine, which can improve catalyst early warming-up performance and reduce exhaust emission.
【００１０】[0010]
【課題を解決するための手段】上記目的を達成するため
に、本発明の請求項１の筒内噴射式内燃機関の触媒早期
暖機制御装置は、触媒の早期暖機が要求される時に成層
燃焼モードに切り換えて圧縮行程で機関出力を発生させ
るための主噴射を行った後に膨張行程で後噴射を行う
が、この際、成層燃焼モードに切り換えてから所定の期
間は後噴射量を減量補正する。ここで、“所定の期間”
は、成層燃焼モードへの切換後の空気系の遅れ（酸素供
給量の遅れ）が生じる期間を見込んで設定すれば良い。
この空気系の遅れが生じる期間に、後噴射量を減量補正
すれば、後噴射量を空気系の遅れを考慮した適正な噴射
量に減量することができる。これにより、成層燃焼モー
ドへの切換直後から後噴射を開始しても、実際の筒内充
填空気量に対して後噴射量が過剰にならず、後噴射の燃
料を確実に燃焼させることができ、成層燃焼モードへの
切換直後から後噴射により排気温度を上昇させて触媒の
暖機を促進でき、始動後の排気エミッションを低減する
ことができる。In order to achieve the above object, a catalyst early warm-up control apparatus for a direct injection type internal combustion engine according to the present invention has a stratification when a catalyst early warm-up is required. After switching to the combustion mode and performing the main injection for generating the engine output in the compression stroke, and then performing the post-injection in the expansion stroke, the post-injection amount is reduced for a predetermined period after switching to the stratified combustion mode. I do. Here, "predetermined period"
May be set in consideration of a period in which a delay in the air system (a delay in the oxygen supply amount) occurs after switching to the stratified combustion mode.
If the post-injection amount is reduced and corrected during the period in which the air system delay occurs, the post-injection amount can be reduced to an appropriate injection amount in consideration of the air system delay. Accordingly, even if the post-injection is started immediately after switching to the stratified combustion mode, the post-injection amount does not become excessive with respect to the actual in-cylinder charged air amount, and the post-injection fuel can be reliably burned. Immediately after switching to the stratified combustion mode, the exhaust gas temperature can be increased by post-injection to promote warming-up of the catalyst, and exhaust emissions after starting can be reduced.
【００１１】この場合、後噴射量の減量補正量は固定値
でも良いが、請求項２のように、後噴射量の減量補正量
を空気系の制御目標値と実測値との偏差に応じて設定す
るようにしても良い。ここで、空気系の制御目標値とし
ては、例えば、吸入空気量、吸気管圧力、スロットル開
度等の制御目標値があり、この制御目標値と実測値との
偏差によって現在の空気系の遅れの程度が分かる。従っ
て、後噴射量の減量補正量を空気系の制御目標値と実測
値との偏差に応じて設定すれば、成層燃焼モードへの切
換直後の実際の筒内充填空気量の増加に追従させて後噴
射量の減量補正量を適正化することができ、触媒早期暖
機性能向上、排気エミッション低減の効果を大きくする
ことができる。In this case, the post-injection amount decrease correction amount may be a fixed value. However, as in claim 2, the post-injection amount decrease correction amount is determined according to the deviation between the control target value of the air system and the actually measured value. You may make it set. Here, as the control target value of the air system, for example, there are control target values such as an intake air amount, an intake pipe pressure, a throttle opening, and the like. You can see the degree of Therefore, if the reduction correction amount of the post-injection amount is set according to the deviation between the control target value of the air system and the actually measured value, it is possible to follow the increase in the actual in-cylinder charged air amount immediately after switching to the stratified combustion mode. The post-injection amount reduction correction amount can be optimized, and the effects of improving catalyst early warm-up performance and reducing exhaust emissions can be enhanced.
【００１２】また、始動直後は、筒内温度が低いため、
主噴射燃料の燃焼熱で後噴射燃料を着火可能な期間が短
くなることを考慮して、請求項３，４のように、触媒の
早期暖機が要求される時に、成層燃焼モードに切り換え
てから所定の期間は後噴射時期を進角補正するようにし
ても良い。ここで、“所定の期間”は、筒内温度が通常
の成層燃焼時の筒内温度に昇温するまでの期間を見込ん
で設定すれば良い。この期間に後噴射時期を進角補正し
て、後噴射時期を主噴射燃料の燃焼時期に近付ければ、
成層燃焼モードへの切換直後の筒内温度が低いときで
も、主噴射燃料の燃焼熱で後噴射燃料を着火可能な時期
に後噴射を行うことができる。これにより、成層燃焼モ
ードへの切換直後から後噴射の燃料を確実に燃焼させて
触媒の暖機を促進できる。Immediately after starting, the temperature in the cylinder is low.
In consideration of the fact that the period during which the post-injection fuel can be ignited by the combustion heat of the main injection fuel is shortened, when the catalyst is required to be quickly warmed up, the mode is switched to the stratified combustion mode. For a predetermined period, the post-injection timing may be advanced. Here, the “predetermined period” may be set in consideration of a period until the in-cylinder temperature rises to the in-cylinder temperature during normal stratified combustion. If the post-injection timing is advanced and corrected during this period, and the post-injection timing approaches the combustion timing of the main injection fuel,
Even when the in-cylinder temperature is low immediately after switching to the stratified combustion mode, the post-injection can be performed at a time when the post-injection fuel can be ignited by the combustion heat of the main injection fuel. As a result, it is possible to reliably burn the post-injection fuel immediately after switching to the stratified combustion mode, thereby promoting the warm-up of the catalyst.
【００１３】この場合、後噴射時期の進角補正量は固定
値でも良いが、請求項５のように、後噴射時期の進角補
正量を空気系の制御目標値と実測値との偏差に応じて設
定するようにしても良い。このようにすれば、成層燃焼
モードへの切換直後の筒内温度の上昇（筒内充填空気量
の増加）に追従させて後噴射時期の進角補正量を適正化
することができ、触媒早期暖機性能向上、排気エミッシ
ョン低減の効果を大きくすることができる。In this case, the amount of advance correction of the post-injection timing may be a fixed value, but the amount of advance correction of the post-injection timing may be a deviation between the control target value of the air system and the actually measured value. You may make it set according to it. This makes it possible to optimize the advance correction amount of the post-injection timing by following the rise in the in-cylinder temperature (increase in the in-cylinder charged air amount) immediately after switching to the stratified combustion mode. The effects of improving warm-up performance and reducing exhaust emissions can be enhanced.
【００１４】[0014]
【発明の実施の形態】［実施形態（１）］以下、本発明
の実施形態（１）を図１乃至図５に基づいて説明する。
まず、図１に基づいてエンジン制御系システム全体の概
略構成を説明する。筒内噴射式内燃機関である直噴エン
ジン１１の吸気管１２の最上流部には、エアクリーナ１
３が設けられ、このエアクリーナ１３の下流側に、ステ
ップモータ１４によって開度調節されるスロットルバル
ブ１５が設けられている。ステップモータ１４がエンジ
ン電子制御回路（以下「ＥＣＵ」と表記する）１６から
の出力信号に基づいて駆動されることで、スロットルバ
ルブ１５の開度（スロットル開度）が制御され、そのス
ロットル開度に応じて各気筒ヘの吸入空気量が調節され
る。スロットルバルブ１５の近傍には、スロットル開度
を検出するスロットルセンサ１７が設けられている。[Embodiment (1)] An embodiment (1) of the present invention will be described below with reference to FIGS.
First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 1 is provided at the most upstream portion of an intake pipe 12 of a direct injection engine 11 which is a direct injection internal combustion engine.
3 is provided, and a throttle valve 15 whose opening is adjusted by a step motor 14 is provided downstream of the air cleaner 13. When the step motor 14 is driven based on an output signal from an engine electronic control circuit (hereinafter referred to as “ECU”) 16, the opening of the throttle valve 15 (throttle opening) is controlled, and the throttle opening is controlled. The amount of intake air to each cylinder is adjusted according to. A throttle sensor 17 for detecting a throttle opening is provided near the throttle valve 15.
【００１５】このスロットルバルブ１５の下流側には、
サージタンク１９が設けられ、このサージタンク１９
に、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２０が接続されている。各気筒の吸気マニホール
ド２０内には、それぞれ第１吸気路２１と第２吸気路２
２が仕切り形成され、これら第１吸気路２１と第２吸気
路２２が、エンジン１１の各気筒に形成された２つの吸
気ポート２３にそれぞれ連結されている。各気筒の第２
吸気路２２内には、スワールコントロール弁２４が配置
されている。各気筒のスワールコントロール弁２４は、
共通のシャフト２５を介してステップモータ２６に連結
されている。このステップモータ２６がＥＣＵ１６から
の出力信号に基づいて駆動されることで、スワールコン
トロール弁２４の開度が制御され、その開度に応じて各
気筒内のスワール流強度が調整される。ステップモータ
２６には、スワールコントロール弁２４の開度を検出す
るスワールコントロール弁センサ２７が取り付けられて
いる。Downstream of the throttle valve 15,
A surge tank 19 is provided.
Is connected to an intake manifold 20 for introducing air into each cylinder of the engine 11. A first intake passage 21 and a second intake passage 2 are provided in the intake manifold 20 of each cylinder.
The first intake passage 21 and the second intake passage 22 are respectively connected to two intake ports 23 formed in each cylinder of the engine 11. The second of each cylinder
A swirl control valve 24 is arranged in the intake passage 22. The swirl control valve 24 of each cylinder is
It is connected to a step motor 26 via a common shaft 25. When the step motor 26 is driven based on an output signal from the ECU 16, the opening of the swirl control valve 24 is controlled, and the swirl flow intensity in each cylinder is adjusted according to the opening. A swirl control valve sensor 27 for detecting the opening of the swirl control valve 24 is attached to the step motor 26.
【００１６】また、エンジン１１の各気筒の上部には、
燃料を筒内に直接噴射する燃料噴射弁２８が取り付けら
れている。燃料タンク（図示せず）から燃料配管４５を
通して燃料デリバリパイプ２９に送られてくる燃料は、
各気筒の燃料噴射弁２８から燃焼室内に噴射され、吸気
ポート２３から導入される吸入空気と混合して混合気が
形成される。燃料デリバリパイプ２９には、燃料の圧力
を検出する燃圧センサ３０が取り付けられている。The upper part of each cylinder of the engine 11
A fuel injection valve 28 for directly injecting fuel into the cylinder is provided. The fuel sent from the fuel tank (not shown) to the fuel delivery pipe 29 through the fuel pipe 45 is
The fuel is injected into the combustion chamber from the fuel injection valve 28 of each cylinder and mixed with the intake air introduced from the intake port 23 to form an air-fuel mixture. A fuel pressure sensor 30 for detecting the pressure of the fuel is attached to the fuel delivery pipe 29.
【００１７】更に、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、各点火プラグの点火によって燃焼室内の混合気が着
火される。また、気筒判別センサ３２は、特定気筒が吸
気上死点に達した時にパルス状の気筒判別信号を出力
し、クランク角センサ３３は、エンジン１１のクランク
シャフトが所定クランク角（例えば３０℃Ａ）回転する
毎にパルス状のクランク角信号を出力し、このクランク
角信号の出力周波数によってエンジン回転速度が検出さ
れる。更に、このクランク角信号と気筒判別信号によっ
て、クランク角の検出や気筒判別が行われる。Further, an ignition plug (not shown) is attached to a cylinder head of the engine 11 for each cylinder, and an air-fuel mixture in a combustion chamber is ignited by ignition of each ignition plug. The cylinder discriminating sensor 32 outputs a pulse-shaped cylinder discriminating signal when the specific cylinder reaches the intake top dead center. The crank angle sensor 33 detects that the crankshaft of the engine 11 has a predetermined crank angle (for example, 30 ° C.). Each time the motor rotates, a pulse-like crank angle signal is output, and the engine rotation speed is detected based on the output frequency of the crank angle signal. Further, based on the crank angle signal and the cylinder discrimination signal, the detection of the crank angle and the cylinder discrimination are performed.
【００１８】一方、エンジン１１の排気ポート３５に
は、排気マニホールド３６を介して排気管３７が接続さ
れている。この排気管３７には、理論空燃比付近で排気
を効率良く浄化する三元触媒３８とＮＯｘ吸蔵型のリー
ンＮＯｘ触媒３９とが直列に配置されている。このリー
ンＮＯｘ触媒３９は、排気中の酸素濃度が高いリーン運
転中に、排気中のＮＯｘを吸着し、空燃比がリッチに切
り換えられて排気中の酸素濃度が低下した時に、吸着し
たＮＯｘを還元浄化して放出する。このリーンＮＯｘ触
媒３９の下流側には、リーンＮＯｘ触媒３９から流出す
る排気中のＮＯｘ濃度を検出するＮＯｘ濃度センサ（図
示せず）が設置され、排気中のＮＯｘ濃度から推定した
リーンＮＯｘ触媒３９のＮＯｘ吸着量が所定値より多く
なった時に一時的に空燃比がリーンからリッチに切り換
えられる。On the other hand, an exhaust pipe 37 is connected to an exhaust port 35 of the engine 11 via an exhaust manifold 36. In the exhaust pipe 37, a three-way catalyst 38 for efficiently purifying exhaust gas near the stoichiometric air-fuel ratio and a NOx storage type lean NOx catalyst 39 are arranged in series. The lean NOx catalyst 39 adsorbs NOx in the exhaust gas during lean operation in which the oxygen concentration in the exhaust gas is high, and reduces the adsorbed NOx when the air-fuel ratio is switched to rich and the oxygen concentration in the exhaust gas drops. Purify and release. Downstream of the lean NOx catalyst 39, a NOx concentration sensor (not shown) for detecting the NOx concentration in the exhaust flowing out of the lean NOx catalyst 39 is provided, and the lean NOx catalyst 39 estimated from the NOx concentration in the exhaust is provided. The air-fuel ratio is temporarily switched from lean to rich when the NOx adsorption amount becomes larger than a predetermined value.
【００１９】また、排気管３７のうちの三元触媒３８の
上流側とサージタンク１９との間には、排気の一部を還
流させるＥＧＲ配管４０が接続され、このＥＧＲ配管４
０の途中に、ＥＧＲ量（排気還流量）を制御するＥＧＲ
弁４１が設けられている。また、アクセルペダル１８に
は、アクセル開度を検出するアクセルセンサ４２が設け
られている。An EGR pipe 40 for recirculating a part of the exhaust gas is connected between the upstream side of the three-way catalyst 38 in the exhaust pipe 37 and the surge tank 19.
EGR controlling the EGR amount (exhaust gas recirculation amount) in the middle of 0
A valve 41 is provided. Further, the accelerator pedal 18 is provided with an accelerator sensor 42 for detecting an accelerator opening.
【００２０】上述した各種センサの出力信号は、ＥＣＵ
１６に入力される。このＥＣＵ１６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）に記憶された制御プログラムに従い、各種センサ
出力に基づき、前述したステップモータ１４，２６、Ｅ
ＧＲ弁４１、燃料噴射弁２８、点火プラグの動作を制御
する。例えば、低・中負荷運転時は、空燃比がリーンと
なるように少量の燃料を圧縮行程で噴射し、点火プラグ
の周辺に部分的に濃いめの混合気を形成して成層燃焼さ
せ、筒内全体としての空燃比をリーンとする（成層燃焼
モード）。また、高負荷運転時や始動時は、理論空燃比
付近又はそれよりも若干リッチとなるように燃料噴射量
を増量し、燃料を吸気行程で噴射して均質燃焼させる
（均質燃焼モード）。このように燃焼モードを切り換え
るＥＣＵ１６の機能が特許請求の範囲でいう燃焼モード
切換手段に相当する役割を果たす。The output signals of the various sensors described above are supplied to the ECU
16 is input. The ECU 16 is mainly composed of a microcomputer, and controls the aforementioned step motors 14, 26, E based on various sensor outputs in accordance with a control program stored in a built-in ROM (storage medium).
The operation of the GR valve 41, the fuel injection valve 28, and the spark plug is controlled. For example, during low / medium load operation, a small amount of fuel is injected in the compression stroke so that the air-fuel ratio becomes lean, a partially rich mixture is formed around the ignition plug, and stratified combustion is performed. The air-fuel ratio as a whole is made lean (stratified combustion mode). During high load operation or startup, the fuel injection amount is increased so as to be near or slightly richer than the stoichiometric air-fuel ratio, and fuel is injected in the intake stroke to perform homogeneous combustion (homogeneous combustion mode). Thus, the function of the ECU 16 for switching the combustion mode plays a role corresponding to the combustion mode switching means in the claims.
【００２１】また、ＥＣＵ１６は、図２に示す触媒早期
暖機制御プログラムを実行することで、三元触媒３８の
早期暖機が要求される時に成層燃焼モードに切り換えて
圧縮行程でエンジン出力を発生させるための主噴射を行
った後に膨張行程で後噴射を行い（図５参照）、主噴射
燃料の燃焼熱で後噴射燃料を燃焼させて排気温度を上昇
させる。更に、触媒早期暖機制御時には、成層燃焼モー
ドに切り換えてから所定の期間は後噴射量を減量補正
し、且つ、後噴射時期を進角補正する（図４参照）。以
下、この触媒早期暖機制御プログラムの処理内容につい
て説明する。The ECU 16 executes the catalyst early warming-up control program shown in FIG. 2 to switch to the stratified combustion mode when the three-way catalyst 38 is required to be warmed up early and generate engine output in the compression stroke. After the main injection for performing the post-injection, post-injection is performed in the expansion stroke (see FIG. 5), and the post-injection fuel is burned by the combustion heat of the main injection fuel to increase the exhaust gas temperature. Further, during the early catalyst warm-up control, the post-injection amount is reduced and the post-injection timing is advanced for a predetermined period after switching to the stratified combustion mode (see FIG. 4). Hereinafter, the processing content of the catalyst early warm-up control program will be described.
【００２２】本プログラムは、イグニッションスイッチ
（図示せず）のオン後に所定クランク角毎に起動され、
特許請求の範囲でいう触媒早期暖機制御手段としての役
割を果たす。本プログラムが起動されると、まずステッ
プ１０１で、三元触媒３８が活性状態になっているか否
かを、触媒温度が活性下限温度（例えば２００℃）以上
であるか否かで判定する。尚、触媒温度の検出は、三元
触媒３８に設置した触媒温度センサ（図示せず）を用い
たり、或は、冷却水温と始動後経過時間等から触媒温度
を推定しても良い。This program is started at every predetermined crank angle after an ignition switch (not shown) is turned on,
It functions as a catalyst early warm-up control means described in the claims. When the program is started, first, in step 101, it is determined whether or not the three-way catalyst 38 is in an active state based on whether or not the catalyst temperature is equal to or higher than an activation lower limit temperature (for example, 200 ° C.). The catalyst temperature may be detected by using a catalyst temperature sensor (not shown) provided in the three-way catalyst 38, or by estimating the catalyst temperature from the cooling water temperature and the elapsed time after the start.
【００２３】ステップ１０１で、三元触媒３８が活性状
態になっていると判定されれば、触媒早期暖機制御を行
う必要がないので、ステップ１０２に進み、成層燃焼モ
ード切換後経過時間カウンタＣＣＮＧのカウント値を０
にリセットして本プログラムを終了する。尚、成層燃焼
モード切換後経過時間カウンタＣＣＮＧは、成層燃焼モ
ード切換後の経過時間をカウントするカウンタである。If it is determined in step 101 that the three-way catalyst 38 is in the active state, it is not necessary to perform the catalyst early warm-up control. Therefore, the routine proceeds to step 102, where the elapsed time counter CCNG after the stratified combustion mode is switched is executed. Count value of 0
And exit this program. Note that the elapsed time counter CCNG after switching to the stratified combustion mode is a counter that counts the elapsed time after switching to the stratified combustion mode.
【００２４】一方、三元触媒３８がまだ活性状態になっ
ていなければ、ステップ１０３に進み、後噴射実行条件
（触媒早期暖機制御実行条件）が成立しているか否かを
判定する。ここで、後噴射実行条件は、成層燃焼モード
に切り換えて後噴射を行っても、安定燃焼可能な運転状
態であることであり、例えば、図３に示すように、エン
ジン回転速度と要求トルクに基づいてエンジン負荷が小
さい領域を後噴射実行領域と判定したり、或は、軽負荷
領域で且つ始動後所定時間以上が経過していること等を
後噴射実行条件としても良い。On the other hand, if the three-way catalyst 38 has not been activated yet, the routine proceeds to step 103, where it is determined whether or not the post-injection execution condition (catalyst early warm-up control execution condition) is satisfied. Here, the post-injection execution condition is that the engine is in an operating state in which stable combustion can be performed even when the post-injection is performed by switching to the stratified combustion mode. For example, as shown in FIG. A region in which the engine load is small may be determined as the post-injection execution region, or a condition in which the engine is in the light load region and a predetermined time or more has elapsed after the start may be set as the post-injection execution condition.
【００２５】始動後でも、後噴射実行条件が成立してい
なければ、後噴射（触媒早期暖機制御）を行わずに、成
層燃焼モード切換後経過時間カウンタＣＣＮＧのカウン
ト値を０にリセットして（ステップ１０２）、本プログ
ラムを終了する。If the post-injection execution condition is not satisfied even after the start, the post-injection (early catalyst warm-up control) is not performed, and the count value of the elapsed time counter after switching to the stratified combustion mode CCNG is reset to 0. (Step 102), this program ends.
【００２６】これに対し、後噴射実行条件が成立してい
れば、ステップ１０４に進み、現在の燃焼モードが成層
燃焼モードであるか否かを判定し、均質燃焼モードであ
れば、ステップ１０５に進み、燃焼モードを均質燃焼モ
ードから成層燃焼モードに切り換え、成層燃焼モード切
換後経過時間カウンタＣＣＮＧのカウント値を０にリセ
ットして（ステップ１０６）、本プログラムを終了す
る。On the other hand, if the post-injection execution condition is satisfied, the routine proceeds to step 104, where it is determined whether or not the current combustion mode is the stratified combustion mode. Then, the combustion mode is switched from the homogeneous combustion mode to the stratified combustion mode, the count value of the elapsed time counter CCNG after switching to the stratified combustion mode is reset to 0 (step 106), and the program ends.
【００２７】一方、後噴射実行条件が成立し、且つ成層
燃焼モードへ切り換えられた後は、ステップ１０７に進
み、現在のエンジン運転状態に応じてマップ等から後噴
射量Ｑ２ＮＤと後噴射時期Ａ２ＮＤを算出する（後噴射
時期Ａ２ＮＤは例えば圧縮上死点を基準にして設定され
る）。この後、ステップ１０８に進み、成層燃焼モード
切換後経過時間カウンタＣＣＮＧのカウント値が所定値
Ｂ以上か否か、つまり、成層燃焼モード切換後の経過時
間が所定時間以上経過したか否かを判定する。ここで、
所定値Ｂは、成層燃焼モードへの切換後の空気系の遅れ
（酸素供給量の遅れ）が生じる期間に相当する値に設定
されている。On the other hand, after the post-injection execution condition is satisfied and the mode is switched to the stratified combustion mode, the routine proceeds to step 107, where the post-injection amount Q2ND and the post-injection timing A2ND are determined from a map or the like according to the current engine operating state. The post-injection timing A2ND is set based on, for example, the compression top dead center. Thereafter, the routine proceeds to step 108, where it is determined whether the count value of the elapsed time counter CCNG after stratified combustion mode switching is equal to or greater than a predetermined value B, that is, whether the elapsed time after switching to the stratified combustion mode has elapsed a predetermined time or more. I do. here,
The predetermined value B is set to a value corresponding to a period during which a delay in the air system (a delay in the oxygen supply amount) occurs after switching to the stratified combustion mode.
【００２８】従って、成層燃焼モード切換後経過時間カ
ウンタＣＣＮＧのカウント値が所定値Ｂ未満であれば、
成層燃焼モードへの切換後の空気系の遅れが生じている
期間であるので、ステップ１０９に進み、成層燃焼モー
ド切換後経過時間カウンタＣＣＮＧをインクリメントし
た後、ステップ１１０に進み、成層燃焼モードへの切換
後の空気系の遅れを考慮して、後噴射量Ｑ２ＮＤを減量
補正すると共に、後噴射時期Ａ２ＮＤを進角補正する。Therefore, if the count value of the elapsed time counter CCNG after switching to the stratified combustion mode is less than the predetermined value B,
Since it is a period during which the air system is delayed after switching to the stratified combustion mode, the routine proceeds to step 109, where the elapsed time counter after switching to the stratified combustion mode counter CCNG is incremented, and then proceeds to step 110 to switch to the stratified combustion mode. In consideration of the delay of the air system after the switching, the post-injection amount Q2ND is reduced and the post-injection timing A2ND is advanced.
【００２９】この際、後噴射量Ｑ２ＮＤの減量補正は、
ステップ１０７で求めた後噴射量Ｑ２ＮＤに補正係数Ｋ
１（Ｋ１＜１．０）を乗算して行い、後噴射時期Ａ２Ｎ
Ｄの進角補正は、ステップ１０７で求めた後噴射時期Ａ
２ＮＤから進角補正量Ｔ１を減算して行う。ここで、補
正係数Ｋ１と進角補正量Ｔ１は固定値でも良いが、成層
燃焼モード切換後経過時間カウンタＣＣＮＧのカウント
値に応じて変化させても良い。例えば、成層燃焼モード
切換後経過時間カウンタＣＣＮＧのカウント値が増加す
るほど、補正係数Ｋ１を大きくして後噴射量Ｑ２ＮＤの
減量補正量を小さくすると共に、進角補正量Ｔ１を小さ
くする（図４参照）。At this time, the post-injection amount Q2ND is reduced by:
The correction coefficient K is added to the post-injection amount Q2ND obtained in step 107.
1 (K1 <1.0), and the post-injection timing A2N
The advance correction of D is performed after the post-injection timing A obtained in step 107.
This is performed by subtracting the advance correction amount T1 from 2ND. Here, the correction coefficient K1 and the advance correction amount T1 may be fixed values, or may be changed according to the count value of the elapsed time counter CCNG after switching to the stratified combustion mode. For example, as the count value of the elapsed time counter after switching to the stratified combustion mode CCNG increases, the correction coefficient K1 is increased to decrease the reduction correction amount of the post-injection amount Q2ND and decrease the advance correction amount T1 (FIG. 4). reference).
【００３０】後噴射量Ｑ２ＮＤの減量補正と後噴射時期
Ａ２ＮＤの進角補正は、成層燃焼モード切換後経過時間
カウンタＣＣＮＧのカウント値が所定値Ｂに達するまで
行われる。これにより、成層燃焼モードへの切換後の空
気系の遅れが生じる期間に、後噴射量Ｑ２ＮＤの減量補
正と後噴射時期Ａ２ＮＤの進角補正が実施される。The correction of the decrease of the post-injection amount Q2ND and the advance correction of the post-injection timing A2ND are performed until the count value of the elapsed time counter CCNG after the stratified combustion mode is switched reaches the predetermined value B. Thus, during the period in which the air system delays after switching to the stratified combustion mode, the decrease correction of the post-injection amount Q2ND and the advance correction of the post-injection timing A2ND are performed.
【００３１】その後、成層燃焼モード切換後経過時間カ
ウンタＣＣＮＧのカウント値が所定値Ｂに達すると、該
カウンタＣＣＮＧのカウント値を所定値Ｂに固定し（ス
テップ１１０）、後噴射量Ｑ２ＮＤの減量補正と後噴射
時期Ａ２ＮＤの進角補正を終了する。これにより、空気
系の遅れが無視できるようになった後は、ステップ１０
７で求めた後噴射量Ｑ２ＮＤと後噴射時期Ａ２ＮＤで後
噴射が実施される。後噴射された燃料は、主噴射燃料の
燃焼熱で着火して燃焼し、排気温度を上昇させて三元触
媒３８の暖機を促進する。Thereafter, when the count value of the elapsed time counter CCNG after switching to the stratified combustion mode reaches the predetermined value B, the count value of the counter CCNG is fixed to the predetermined value B (step 110), and the reduction of the post-injection amount Q2ND is corrected. Then, the advance correction of the post-injection timing A2ND is ended. As a result, after the delay of the air system can be ignored, step 10 is executed.
The post-injection is performed with the post-injection amount Q2ND and the post-injection timing A2ND determined in step S7. The post-injected fuel is ignited by the combustion heat of the main injected fuel and burns, raising the exhaust gas temperature and promoting warm-up of the three-way catalyst 38.
【００３２】以上説明した本実施形態（１）の触媒早期
暖機制御の実行例を図４のタイムチャートを用いて説明
する。エンジン始動時は、後噴射実行条件（触媒早期暖
機制御実行条件）が不成立となり、均質燃焼モードでエ
ンジン１１が始動される。始動後に、後噴射実行条件が
成立すると、要求燃焼モードが成層燃焼モードに切り換
えられ、直ちに、空気系（スロットルバルブ１５、スワ
ールコントロール弁２４等）が成層燃焼時の制御目標値
に切り換えられる。この際、要求燃焼モードが成層燃焼
モードに切り換えられると同時に、吸入空気量の目標値
がステップ状に増加するが、空気系の遅れが生じるた
め、実際の吸入空気量は目標値に対して遅れて増加す
る。An execution example of the catalyst early warm-up control of the embodiment (1) described above will be described with reference to a time chart of FIG. When the engine is started, the post-injection execution condition (catalyst early warm-up control execution condition) is not satisfied, and the engine 11 is started in the homogeneous combustion mode. When the post-injection execution condition is satisfied after the start, the required combustion mode is switched to the stratified combustion mode, and immediately, the air system (throttle valve 15, swirl control valve 24, etc.) is switched to the control target value for stratified combustion. At this time, the target value of the intake air amount increases stepwise at the same time as the required combustion mode is switched to the stratified combustion mode, but the actual intake air amount is delayed with respect to the target value because the air system is delayed. Increase.
【００３３】空気系の切り換え（吸入空気量の目標値の
切換）から少し遅れて、主噴射時期が圧縮行程に切り換
えられ、成層燃焼に切り換えられると同時に、後噴射が
開始される。成層燃焼への切換直後は、まだ吸入空気量
が目標値まで増加していないため、成層燃焼への切換直
後に後噴射を通常の成層燃焼時の後噴射量で開始する
と、筒内の空気量（酸素量）が不足して、後噴射の燃料
を十分に燃焼させることができず、排気エミッションが
悪化する結果となる。Slightly after the switching of the air system (switching of the target value of the intake air amount), the main injection timing is switched to the compression stroke, and is switched to stratified charge combustion, and at the same time, post-injection is started. Immediately after switching to stratified combustion, since the intake air amount has not yet increased to the target value, if post-injection is started at the normal post-injection amount during stratified combustion immediately after switching to stratified combustion, the air amount in the cylinder Insufficient (oxygen amount) makes it impossible to sufficiently burn the fuel for post-injection, resulting in deterioration of exhaust emission.
【００３４】そこで、本実施形態（１）では、成層燃焼
（圧縮行程噴射）に切り換わってから所定時間Ｂが経過
するまでの期間、つまり、吸入空気量が目標値付近まで
増加するまでの期間は、後噴射量を減量補正する。これ
により、後噴射量を空気系の遅れを考慮した適正な噴射
量に減量できるため、成層燃焼への切換直後から後噴射
を開始しても、実際の筒内充填空気量に対して後噴射量
が過剰にならず、後噴射の燃料を確実に燃焼させること
ができ、成層燃焼への切換直後から後噴射により排気温
度を上昇させて三元触媒３８の暖機を促進でき、始動後
の排気エミッションを低減することができる。Therefore, in the present embodiment (1), the period from the time of switching to the stratified combustion (compression stroke injection) until the predetermined time B elapses, that is, the period until the intake air amount increases to near the target value. Corrects the post-injection amount by decreasing it. As a result, the post-injection amount can be reduced to an appropriate injection amount in consideration of the delay in the air system, so that even if the post-injection is started immediately after switching to stratified combustion, the post-injection is performed with respect to the actual in-cylinder charged air amount. The amount of fuel is not excessively increased, and the fuel of the post-injection can be reliably burned. Immediately after switching to the stratified charge combustion, the exhaust temperature can be increased by the post-injection to promote the warm-up of the three-way catalyst 38. Exhaust emissions can be reduced.
【００３５】更に、後噴射開始直後（成層燃焼への切換
直後）は、筒内温度が低いため、主噴射燃料の燃焼熱で
後噴射燃料を着火可能な期間が短くなることを考慮し
て、本実施形態（１）では、成層燃焼に切り換わってか
ら所定時間Ｂが経過するまでの期間は、後噴射時期を進
角補正するようにしている。これにより、噴射時期を主
噴射燃料の燃焼時期に近付けることができるため、成層
燃焼への切換直後の筒内温度が低いときでも、主噴射燃
料の燃焼熱で後噴射燃料を着火可能な時期に後噴射を行
うことができ、成層燃焼モードへの切換直後から後噴射
の燃料を確実に燃焼させて三元触媒３８の暖機を促進で
きる。Further, immediately after the start of post-injection (immediately after switching to stratified combustion), since the in-cylinder temperature is low, the period in which the post-injection fuel can be ignited by the combustion heat of the main injection fuel is shortened. In the present embodiment (1), the advance angle of the post-injection timing is corrected during a period from the time of switching to the stratified combustion to the elapse of the predetermined time B. This makes it possible to make the injection timing close to the combustion timing of the main injection fuel, so that even when the in-cylinder temperature immediately after switching to stratified combustion is low, the post injection fuel can be ignited by the combustion heat of the main injection fuel. The post-injection can be performed, and the fuel of the post-injection can be reliably burned immediately after switching to the stratified combustion mode, and the warm-up of the three-way catalyst 38 can be promoted.
【００３６】尚、本実施形態（１）では、成層燃焼（圧
縮行程噴射）に切り換わってから所定時間Ｂが経過する
までの期間に、後噴射量の減量補正と後噴射時期の進角
補正の両方を実施するようにしたが、いずれか一方のみ
を実施するようにしても良い。また、後噴射量の減量補
正と後噴射時期の進角補正の両方を実施する場合、後噴
射量の減量補正を実施する時間と後噴射時期の進角補正
を実施する時間を異ならせても良く、例えば、後者を前
者よりも短くしても良い。In this embodiment (1), after the predetermined time B has elapsed since the switching to the stratified charge combustion (compression stroke injection), the post-injection amount reduction correction and the post-injection timing advance correction are performed. Although both are performed, only one of them may be performed. Further, when both the post-injection amount decrease correction and the post-injection timing advance correction are performed, the time for performing the post-injection amount decrease correction and the time for performing the post-injection timing advance correction may be different. For example, the latter may be shorter than the former.
【００３７】［実施形態（２）］上記実施形態（１）で
は、後噴射量の減量補正量と後噴射時期の進角補正量を
成層燃焼への切換後の経過時間で設定したが、図６乃至
図８に示す本発明の実施形態（２）では、後噴射量の減
量補正量と後噴射時期の進角補正量を、吸入空気量の目
標値と実測値との偏差に応じて設定する。[Embodiment (2)] In the embodiment (1), the post-injection amount decrease correction amount and the post-injection timing advance correction amount are set by the elapsed time after switching to the stratified combustion. In the embodiment (2) of the present invention shown in FIGS. 6 to 8, the reduction amount of the post-injection amount and the advance correction amount of the post-injection timing are set according to the deviation between the target value and the actually measured value of the intake air amount. I do.
【００３８】本実施形態（２）では、図６のプログラム
によって触媒早期暖機制御が次のように行われる。ま
ず、ステップ２０１で、三元触媒３８が活性状態になっ
ているか否かを判定し、既に、三元触媒３８が活性状態
になっていれば、以降の処理を行うことなく、本プログ
ラムを終了する。In this embodiment (2), the catalyst early warm-up control is performed as follows by the program of FIG. First, in step 201, it is determined whether or not the three-way catalyst 38 has been activated. If the three-way catalyst 38 has already been activated, the program is terminated without performing the subsequent processing. I do.
【００３９】一方、三元触媒３８がまだ活性状態になっ
ていなければ、ステップ２０２に進み、前記実施形態
（１）と同じ方法で、後噴射実行条件（触媒早期暖機制
御実行条件）が成立しているか否かを判定する。もし、
後噴射実行条件が成立していなければ、以降の処理を行
うことなく、本プログラムを終了する。On the other hand, if the three-way catalyst 38 has not been activated yet, the routine proceeds to step 202, where the post-injection execution condition (catalyst early warm-up control execution condition) is satisfied in the same manner as in the embodiment (1). It is determined whether or not. if,
If the post-injection execution condition is not satisfied, the program is terminated without performing the subsequent processing.
【００４０】これに対し、後噴射実行条件が成立してい
れば、ステップ２０３に進み、現在の燃焼モードが成層
燃焼モードであるか否かを判定し、均質燃焼モードであ
れば、ステップ２０４に進み、燃焼モードを均質燃焼モ
ードから成層燃焼モードに切り換えて本プログラムを終
了する。On the other hand, if the post-injection execution condition is satisfied, the routine proceeds to step 203, where it is determined whether or not the current combustion mode is the stratified combustion mode. Then, the combustion mode is switched from the homogeneous combustion mode to the stratified combustion mode, and the program ends.
【００４１】一方、後噴射実行条件が成立し、且つ成層
燃焼モードへ切り換えられた後は、ステップ２０５に進
み、現在のエンジン運転状態に応じてマップ等から後噴
射量Ｑ２ＮＤと後噴射時期Ａ２ＮＤを算出する。この
後、ステップ２０６に進み、吸入空気量センサ（図示せ
ず）で測定した実吸入空気量が目標吸入空気量付近まで
増加したか否かを次式により判定する。 実吸入空気量≧目標吸入空気量−α ここで、αは、吸入空気量センサの検出誤差を見込むた
めの補正係数である。また、目標吸入空気量は、ＥＣＵ
１６（制御目標値設定手段）によって設定される。On the other hand, after the post-injection execution condition is satisfied and the mode is switched to the stratified combustion mode, the routine proceeds to step 205, where the post-injection amount Q2ND and the post-injection timing A2ND are determined from a map or the like according to the current engine operating state. calculate. Thereafter, the routine proceeds to step 206, where it is determined by the following equation whether or not the actual intake air amount measured by the intake air amount sensor (not shown) has increased to near the target intake air amount. Actual intake air amount ≧ Target intake air amount−α Here, α is a correction coefficient to allow for a detection error of the intake air amount sensor. The target intake air amount is determined by the ECU
16 (control target value setting means).
【００４２】もし、実吸入空気量＜目標吸入空気量−α
であれば、まだ実吸入空気量が目標吸入空気量付近まで
増加していない（空気系の遅れを無視できない）ため、
ステップ２０７に進み、後噴射量の減量補正量Ｑｓと後
噴射時期の進角補正量Ｔｓを目標吸入空気量と実吸入空
気量との偏差に応じて図７及び図８のマップにより算出
する。これにより、目標吸入空気量と実吸入空気量との
偏差が大きくなるほど、後噴射量の減量補正量Ｑｓと後
噴射時期の進角補正量Ｔｓが大きい値に設定される。If the actual intake air amount <the target intake air amount−α
Then, since the actual intake air amount has not yet increased to near the target intake air amount (the delay of the air system cannot be ignored),
Proceeding to step 207, the post-injection amount decrease correction amount Qs and the post-injection timing advance angle correction amount Ts are calculated according to the deviation between the target intake air amount and the actual intake air amount using the maps of FIGS. As a result, as the deviation between the target intake air amount and the actual intake air amount increases, the post-injection amount decrease correction amount Qs and the post-injection timing advance correction amount Ts are set to larger values.
【００４３】この後、ステップ２０９に進み、ステップ
２０５で求めた後噴射量Ｑ２ＮＤを減量補正量Ｑｓで減
量補正し（Ｑ２ＮＤ←Ｑ２ＮＤ−Ｑｓ）、更に、ステッ
プ２０５で求めた後噴射時期Ａ２ＮＤを進角補正量Ｔｓ
で進角補正する（Ａ２ＮＤ←Ａ２ＮＤ−Ｔｓ）。Thereafter, the routine proceeds to step 209, in which the post-injection amount Q2ND determined in step 205 is reduced by the reduced amount Qs (Q2ND ← Q2ND-Qs), and the post-injection timing A2ND determined in step 205 is advanced. Angle correction amount Ts
(A2ND ← A2ND-Ts).
【００４４】その後、実吸入空気量が目標吸入空気量付
近まで増加した時点で、ステップ２０６からステップ２
０８に進み、減量補正量Ｑｓと進角補正量Ｔｓを共に０
にセットする。これにより、後噴射量Ｑ２ＮＤの減量補
正と後噴射時期Ａ２ＮＤの進角補正を終了し、ステップ
２０５で求めた後噴射量Ｑ２ＮＤと後噴射時期Ａ２ＮＤ
で後噴射を実施する。Thereafter, when the actual intake air amount has increased to near the target intake air amount, the routine proceeds from step 206 to step 2.
08, the reduction correction amount Qs and the advance angle correction amount Ts are both set to 0.
Set to. As a result, the reduction correction of the post-injection amount Q2ND and the advance correction of the post-injection timing A2ND are completed, and the post-injection amount Q2ND and the post-injection timing A2ND obtained in step 205 are completed.
Perform post-injection.
【００４５】以上説明した本実施形態（２）では、後噴
射量の減量補正量Ｑｓと後噴射時期の進角補正量Ｔｓ
を、目標吸入空気量と実吸入空気量との偏差に応じて設
定するので、成層燃焼モードへの切換直後の実際の筒内
充填空気量の増加や筒内温度の上昇に追従させて後噴射
量の減量補正量Ｑｓと後噴射時期の進角補正量Ｔｓを適
正化することができ、触媒早期暖機性能向上、排気エミ
ッション低減の効果を大きくすることができる。In the embodiment (2) described above, the post-injection amount decrease correction amount Qs and the post-injection timing advance correction amount Ts
Is set in accordance with the deviation between the target intake air amount and the actual intake air amount, so that the post-injection follows the actual increase in the in-cylinder charged air amount and the in-cylinder temperature immediately after switching to the stratified combustion mode. The amount reduction correction amount Qs of the amount and the advance correction amount Ts of the post-injection timing can be optimized, and the effect of improving the catalyst early warm-up performance and reducing the exhaust emission can be enhanced.
【００４６】尚、本実施形態（２）では、成層燃焼モー
ド切換後の空気系の遅れを評価するパラメータとして、
目標吸入空気量と実吸入空気量との偏差を用いたが、例
えば目標吸気管圧力と実吸気管圧力との偏差、又は、目
標スロットル開度と実スロットル開度との偏差を用いて
も良い。In this embodiment (2), the parameters for evaluating the delay of the air system after switching the stratified combustion mode are as follows:
Although the deviation between the target intake air amount and the actual intake air amount is used, for example, a deviation between the target intake pipe pressure and the actual intake pipe pressure, or a deviation between the target throttle opening and the actual throttle opening may be used. .
【００４７】また、本実施形態（２）では、後噴射量の
減量補正と後噴射時期の進角補正の両方を実施するよう
にしたが、いずれか一方のみを実施するようにしても良
い。Further, in the present embodiment (2), both the reduction correction of the post-injection amount and the advance correction of the post-injection timing are performed, but only one of them may be performed.
【図１】本発明の実施形態（１）におけるエンジン制御
系システム全体の概略構成を示す図FIG. 1 is a diagram showing a schematic configuration of an entire engine control system according to an embodiment (1) of the present invention.
【図２】実施形態（１）の触媒早期暖機制御プログラム
の処理の流れを示すフローチャートFIG. 2 is a flowchart showing a processing flow of a catalyst early warm-up control program according to an embodiment (1).
【図３】後噴射実行領域を決定するマップを概念的に示
す図FIG. 3 is a diagram conceptually showing a map for determining a post-injection execution area.
【図４】実施形態（１）の触媒早期暖機制御の実行例を
示すタイムチャートFIG. 4 is a time chart showing an execution example of a catalyst early warm-up control according to the embodiment (1).
【図５】主噴射と後噴射と筒内温度との関係を示すタイ
ムチャートFIG. 5 is a time chart showing the relationship between main injection, post-injection, and in-cylinder temperature;
【図６】実施形態（２）の触媒早期暖機制御プログラム
の処理の流れを示すフローチャートFIG. 6 is a flowchart showing a processing flow of a catalyst early warm-up control program according to the embodiment (2).
【図７】目標吸入空気量と実吸入空気量との偏差から後
噴射量の減量補正量Ｑｓを求めるマップを概念的に示す
図FIG. 7 is a diagram conceptually showing a map for calculating a post-injection amount reduction correction amount Qs from a deviation between a target intake air amount and an actual intake air amount.
【図８】目標吸入空気量と実吸入空気量との偏差から後
噴射時期の進角補正量Ｔｓを求めるマップを概念的に示
す図FIG. 8 is a diagram conceptually showing a map for obtaining a post-injection timing advance correction amount Ts from a deviation between a target intake air amount and an actual intake air amount.
１１…直噴エンジン（筒内噴射式内燃機関）、１２…吸
気管、１５…スロットルバルブ、１６…ＥＣＵ（燃焼モ
ード切換手段，触媒早期暖機制御手段，制御目標値設定
手段）、２４…スワールコントロール弁、２８…燃料噴
射弁、３７…排気管、３８…三元触媒、３９…リーンＮ
Ｏｘ触媒、４１…ＥＧＲ弁。11: direct injection engine (in-cylinder injection type internal combustion engine), 12: intake pipe, 15: throttle valve, 16: ECU (combustion mode switching means, catalyst early warm-up control means, control target value setting means), 24: swirl Control valve, 28: fuel injection valve, 37: exhaust pipe, 38: three-way catalyst, 39: lean N
Ox catalyst, 41 ... EGR valve.
フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｆ０２Ｄ 45/00 ３１２ Ｆ０２Ｄ 45/00 ３１２Ｒ Ｆターム(参考） 3G084 BA05 BA13 BA15 CA02 DA10 FA00 FA10 FA19 FA20 FA38 FA39 3G301 HA01 HA04 HA13 HA16 JA21 KA05 LA01 LA05 MA11 MA19 MA23 MA27 PA00Z PA11Z PB08Z PD12Z PE03Z PE05Z PE08Z PF03Z Continued on the front page (51) Int.Cl. 7 Identification code FI Theme coat II (reference) F02D 45/00 312 F02D 45/00 312R F term (reference) 3G084 BA05 BA13 BA15 CA02 DA10 FA00 FA10 FA19 FA20 FA38 FA39 3G301 HA01 HA04 HA13 HA16 JA21 KA05 LA01 LA05 MA11 MA19 MA23 MA27 PA00Z PA11Z PB08Z PD12Z PE03Z PE05Z PE08Z PF03Z
Claims (5)
て燃焼させ、その排出ガスを触媒で浄化するようにした
筒内噴射式内燃機関において、 吸気行程で燃料を噴射して均質燃焼させる均質燃焼モー
ドと圧縮行程で燃料を噴射して成層燃焼させる成層燃焼
モードとを運転状態に応じて切り換える燃焼モード切換
手段と、 前記触媒の早期暖機が要求される時に成層燃焼モードに
切り換えて圧縮行程で機関出力を発生させるための主噴
射を行った後に膨張行程で後噴射を行って排気温度を上
昇させる触媒早期暖機制御手段とを備え、 前記触媒早期暖機制御手段は、前記触媒の早期暖機が要
求される時に成層燃焼モードに切り換えてから所定の期
間は後噴射量を減量補正することを特徴とする筒内噴射
式内燃機関の触媒早期暖機制御装置。1. A cylinder injection type internal combustion engine in which fuel is directly injected into a cylinder from a fuel injection valve and burned, and exhaust gas is purified by a catalyst. Combustion mode switching means for switching between a homogeneous combustion mode to be performed and a stratified combustion mode for injecting fuel in a compression stroke to perform stratified combustion in accordance with an operation state; and switching to a stratified combustion mode when early warm-up of the catalyst is required. Catalyst early warm-up control means for increasing the exhaust gas temperature by performing post-injection in the expansion stroke after performing main injection for generating the engine output in the compression stroke, wherein the catalyst early warm-up control means comprises the catalyst A catalyst early warming-up control device for a direct injection internal combustion engine, characterized in that the post-injection amount is reduced and corrected for a predetermined period after switching to the stratified combustion mode when the early warm-up is required.
設定する制御目標値設定手段を備え、 前記触媒早期暖機制御手段は、前記後噴射量の減量補正
量を前記空気系の制御目標値と実測値との偏差に応じて
設定することを特徴とする請求項１に記載の筒内噴射式
内燃機関の触媒早期暖機制御装置。2. A control target value setting means for setting a control target value of an air system in accordance with an operation state, wherein the catalyst early warm-up control means controls a reduction correction amount of the post-injection amount by controlling the air system. 2. The catalyst early warm-up control device for a direct injection internal combustion engine according to claim 1, wherein the controller is set in accordance with a deviation between a target value and an actually measured value.
の早期暖機が要求される時に成層燃焼モードに切り換え
てから所定の期間は後噴射時期を進角補正することを特
徴とする請求項１又は２に記載の筒内噴射式内燃機関の
触媒早期暖機制御装置。3. The catalyst early warm-up control means performs advancing correction of a post-injection timing for a predetermined period after switching to a stratified combustion mode when early warm-up of the catalyst is required. Item 3. A catalyst early warm-up control device for a direct injection internal combustion engine according to Item 1 or 2.
て燃焼させ、その排出ガスを触媒で浄化するようにした
筒内噴射式内燃機関において、 吸気行程で燃料を噴射して均質燃焼させる均質燃焼モー
ドと圧縮行程で燃料を噴射して成層燃焼させる成層燃焼
モードとを運転状態に応じて切り換える燃焼モード切換
手段と、 前記触媒の早期暖機が要求される時に成層燃焼モードに
切り換えて圧縮行程で機関出力を発生させるための主噴
射を行った後に膨張行程で後噴射を行って排気温度を上
昇させる触媒早期暖機制御手段とを備え、 前記触媒早期暖機制御手段は、前記触媒の早期暖機が要
求される時に成層燃焼モードに切り換えてから所定の期
間は後噴射時期を進角補正することを特徴とする筒内噴
射式内燃機関の触媒早期暖機制御装置。4. A cylinder injection type internal combustion engine in which fuel is directly injected into a cylinder from a fuel injection valve to burn the fuel, and the exhaust gas is purified by a catalyst. Combustion mode switching means for switching between a homogeneous combustion mode to be performed and a stratified combustion mode for injecting fuel in a compression stroke to perform stratified combustion in accordance with an operation state; and switching to a stratified combustion mode when early warm-up of the catalyst is required. Catalyst early warm-up control means for increasing the exhaust gas temperature by performing post-injection in the expansion stroke after performing main injection for generating the engine output in the compression stroke, wherein the catalyst early warm-up control means comprises the catalyst A catalyst early warming-up control device for a direct injection internal combustion engine, wherein after a switchover to a stratified combustion mode is performed when an early warming-up is required, the post-injection timing is advanced for a predetermined period.
設定する制御目標値設定手段を備え、 前記触媒早期暖機制御手段は、前記後噴射時期の進角補
正量を前記空気系の制御目標値と実測値との偏差に応じ
て設定することを特徴とする請求項４に記載の筒内噴射
式内燃機関の触媒早期暖機制御装置。5. A control system according to claim 1, further comprising control target value setting means for setting a control target value for the air system in accordance with an operation state, wherein the catalyst early warm-up control means sets the advance correction amount of the post-injection timing to the air system. 5. The control device according to claim 4, wherein the control value is set in accordance with a deviation between the control target value and the actually measured value.
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|---|---|---|---|
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
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| KR100460904B1 (en) * | 2002-09-10 | 2004-12-09 | 현대자동차주식회사 | Warm-up controlling device of vehicle and method thereof |
| JP2005061268A (en) * | 2003-08-08 | 2005-03-10 | Hitachi Ltd | Combustion control device and method of cylinder injection type engine |
| JP2007154824A (en) * | 2005-12-07 | 2007-06-21 | Toyota Motor Corp | Combustion control device for internal combustion engine |
| JP2008215096A (en) * | 2007-02-28 | 2008-09-18 | Honda Motor Co Ltd | Fuel control device for internal combustion engine |
| US7694507B2 (en) | 2004-11-25 | 2010-04-13 | Toyota Jidosha Kabushiki Kaisha | Control apparatus of internal combustion engine |
| JP2012017664A (en) * | 2010-07-06 | 2012-01-26 | Toyota Motor Corp | Control device of internal combustion engine |
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| JP2015117650A (en) * | 2013-12-19 | 2015-06-25 | マツダ株式会社 | Control device of direct injection engine |
| CN113464294A (en) * | 2020-03-31 | 2021-10-01 | 本田技研工业株式会社 | Fuel injection control device |
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2000
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| KR100460904B1 (en) * | 2002-09-10 | 2004-12-09 | 현대자동차주식회사 | Warm-up controlling device of vehicle and method thereof |
| JP2005061268A (en) * | 2003-08-08 | 2005-03-10 | Hitachi Ltd | Combustion control device and method of cylinder injection type engine |
| US7694507B2 (en) | 2004-11-25 | 2010-04-13 | Toyota Jidosha Kabushiki Kaisha | Control apparatus of internal combustion engine |
| JP2007154824A (en) * | 2005-12-07 | 2007-06-21 | Toyota Motor Corp | Combustion control device for internal combustion engine |
| JP4572827B2 (en) * | 2005-12-07 | 2010-11-04 | トヨタ自動車株式会社 | Combustion control device for internal combustion engine |
| JP2008215096A (en) * | 2007-02-28 | 2008-09-18 | Honda Motor Co Ltd | Fuel control device for internal combustion engine |
| JP2012017664A (en) * | 2010-07-06 | 2012-01-26 | Toyota Motor Corp | Control device of internal combustion engine |
| JP2014055551A (en) * | 2012-09-12 | 2014-03-27 | Nippon Soken Inc | Control device of internal combustion engine |
| JP2015117650A (en) * | 2013-12-19 | 2015-06-25 | マツダ株式会社 | Control device of direct injection engine |
| CN113464294A (en) * | 2020-03-31 | 2021-10-01 | 本田技研工业株式会社 | Fuel injection control device |
| CN113464294B (en) * | 2020-03-31 | 2023-04-25 | 本田技研工业株式会社 | Fuel injection control device |
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