JP2000282920A - Control device of internal combustion engine - Google Patents
Control device of internal combustion engineInfo
- Publication number
- JP2000282920A JP2000282920A JP11090506A JP9050699A JP2000282920A JP 2000282920 A JP2000282920 A JP 2000282920A JP 11090506 A JP11090506 A JP 11090506A JP 9050699 A JP9050699 A JP 9050699A JP 2000282920 A JP2000282920 A JP 2000282920A
- Authority
- JP
- Japan
- Prior art keywords
- exhaust
- additional fuel
- cylinder
- combustion
- fuel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- 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
Landscapes
- Exhaust Gas After Treatment (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
- Exhaust Silencers (AREA)
- Supercharger (AREA)
- Control Of Throttle Valves Provided In The Intake System Or In The Exhaust System (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、気筒内に燃料を直
接噴射して燃焼させる筒内噴射式の内燃機関制御装置に
関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct injection type internal combustion engine control apparatus for directly injecting fuel into a cylinder and burning the fuel.
【0002】[0002]
【従来の技術】近年、低燃費、低排気エミッション、高
出力の特長を兼ね備えた筒内噴射エンジンの需要が急増
している。この筒内噴射エンジンは、一般に成層燃焼方
式を採用するものが多い。成層燃焼方式では、圧縮行程
後期に燃料を噴射し、燃料と空気との混合気を成層化し
て点火プラグ付近に比較的濃い混合気を形成し、この混
合気に着火させることで、混合気全体として大幅にリー
ンな空燃比での燃焼を可能とするものである。2. Description of the Related Art In recent years, the demand for an in-cylinder injection engine having features of low fuel consumption, low exhaust emission, and high output has been rapidly increasing. Many of these in-cylinder injection engines generally adopt a stratified combustion system. In the stratified combustion system, fuel is injected late in the compression stroke, the mixture of fuel and air is stratified to form a relatively rich mixture near the spark plug, and this mixture is ignited to form the entire mixture. This enables combustion at a significantly lean air-fuel ratio.
【0003】このような成層燃焼方式では、熱効率が高
く排気ガスへの熱損失が少なくなると共に、単位燃料当
たりの吸入空気量が多いこと等から、従来型エンジン
(吸気ポート噴射エンジン)と比較して排気温度が大幅
に低下する。このため、特にアイドリングを含めた低負
荷領域では、排気温度が従来型エンジンの排気温度を前
提として設計された触媒の活性下限温度よりも低くなっ
てしまい、結果として排気浄化性能が悪化してしまう事
態が発生するおそれがある。[0003] Such a stratified combustion system has high thermal efficiency, reduces heat loss to exhaust gas, and has a large amount of intake air per unit fuel. Therefore, such a stratified combustion system is compared with a conventional engine (intake port injection engine). The exhaust temperature drops significantly. Therefore, particularly in a low load region including idling, the exhaust gas temperature becomes lower than the activation lower limit temperature of the catalyst designed based on the exhaust gas temperature of the conventional engine, and as a result, the exhaust gas purification performance deteriorates. A situation may occur.
【0004】この対策として、特開平8−100638
号公報に示すように、点火前の燃料の噴射(主燃料の噴
射)に加え、点火後の膨張行程初期から中期にかけて追
加燃料の噴射を行い、この追加燃料を点火による主燃料
の燃焼(主燃焼)の火炎伝播により後燃焼させて排気温
度を上昇させることで、触媒を活性化させる技術が提案
されている。As a countermeasure against this, Japanese Patent Laid-Open Publication No. Hei 8-100638
As shown in the publication, in addition to fuel injection before ignition (injection of main fuel), additional fuel is injected from the initial stage to the middle stage of the expansion stroke after ignition, and the additional fuel is used for combustion of main fuel by ignition (main fuel injection). There has been proposed a technique of activating a catalyst by raising the exhaust gas temperature by post-combustion by flame propagation of (combustion).
【0005】[0005]
【発明が解決しようとする課題】しかしながら、前述の
公報の技術では、追加燃料噴射を膨張行程初期から中期
に行うとしているが、膨張行程初期に燃料を噴射した場
合には、主燃焼の火炎が残存する高温高圧下で追加燃料
が噴射されるため、噴射直後から追加燃料が着火し始め
る。その結果、追加燃料が十分に微粒化する前に、燃料
滴の外周が燃え始めて燃料滴の内部が炭化してしまい、
スモークが発生するという問題が生じる。However, in the technique disclosed in the above-mentioned publication, the additional fuel injection is performed from the initial stage of the expansion stroke to the middle stage. However, when the fuel is injected in the early stage of the expansion stroke, the flame of the main combustion is generated. Since the additional fuel is injected under the remaining high temperature and high pressure, the additional fuel starts to ignite immediately after the injection. As a result, before the additional fuel is sufficiently atomized, the outer periphery of the fuel droplet starts burning and the inside of the fuel droplet carbonizes,
There is a problem that smoke is generated.
【0006】また、前述の公報では、追加燃料の噴射量
について全く言及されていないが、追加燃料の噴射量に
は最適値が存在し、追加燃料の噴射量が少ない場合に
は、着火に至らず、未燃ガス(炭化水素)が排出されて
排気エミッションが悪化したり、排気温度を上昇させる
ことができない。反対に、追加燃料の噴射量が多い場合
には、主燃焼後の筒内ガス中の残存酸素量に対し、過剰
噴射分は、燃焼せずに未燃HCとして排出されてしま
い、排気エミッションが悪化したり、スモークが発生し
たり、過剰な燃料噴射によって燃費が悪化する原因にも
なる。Although the above-mentioned publication does not mention the injection amount of the additional fuel at all, there is an optimum value for the injection amount of the additional fuel. Therefore, unburned gas (hydrocarbon) is exhausted to deteriorate exhaust emission or increase exhaust temperature. Conversely, when the amount of additional fuel injected is large, the excess injection is discharged as unburned HC without burning, relative to the amount of residual oxygen in the in-cylinder gas after main combustion, and exhaust emissions are reduced. It also causes deterioration, generation of smoke, and deterioration of fuel efficiency due to excessive fuel injection.
【0007】また、前述の公報では、アイドリングを含
めた低負荷域で、追加燃料を噴射するようにしている
が、エンジンが暖機されていない冷間時のようにエンジ
ンフリクションが高い状態で成層燃焼を行うと、圧縮行
程で噴射された燃料が十分に気化する前に点火すること
になり、燃焼が安定せず、エンジン振動の増加を招くこ
とになる。Further, in the above-mentioned publication, additional fuel is injected in a low load region including idling. However, stratification is performed in a state where engine friction is high such as in a cold state where the engine is not warmed up. When the combustion is performed, the fuel injected in the compression stroke is ignited before being sufficiently vaporized, so that the combustion is not stabilized and the engine vibration is increased.
【0008】ところで、筒内噴射エンジンは、混合気の
空燃比をリーンにして、酸素過剰状態で混合気を燃焼さ
せるため、排気ガス中のNOx(窒素酸化物)の量が多
くなる傾向があり、その対策として、排気管にNOx吸
蔵型のリーンNOx触媒を設置することが多い。このリ
ーンNOx触媒は、排気ガス中の酸素濃度が高いリーン
運転中に、排気ガス中のNOxを吸蔵し、空燃比がリッ
チ又は理論空燃比に切り換えられて排気ガス中の酸素濃
度が低下した時に、それまでに吸蔵したNOxを還元浄
化する。従って、リーンNOx触媒のNOx浄化性能を
維持するためには、リーン運転中に、時々、リッチ運転
(又はストイキ運転)に切り換える必要がある。しか
し、リーン運転からリッチ運転に切り換える際に、燃料
噴射量を増量すると、トルクショックが発生し、ドライ
バビリティが低下する欠点がある。In the cylinder injection engine, since the air-fuel ratio of the air-fuel mixture is made lean and the air-fuel mixture is burned in an excessive oxygen state, the amount of NOx (nitrogen oxide) in the exhaust gas tends to increase. As a countermeasure, a NOx storage type lean NOx catalyst is often installed in the exhaust pipe. This lean NOx catalyst stores NOx in the exhaust gas during lean operation in which the oxygen concentration in the exhaust gas is high, and when the air-fuel ratio is switched to a rich or stoichiometric air-fuel ratio and the oxygen concentration in the exhaust gas decreases. Then, the NOx stored so far is reduced and purified. Therefore, in order to maintain the NOx purification performance of the lean NOx catalyst, it is necessary to switch to the rich operation (or the stoichiometric operation) from time to time during the lean operation. However, when switching from the lean operation to the rich operation, if the fuel injection amount is increased, torque shock occurs and drivability is reduced.
【0009】また、更なる高出力化、省燃費化を狙って
筒内噴射エンジンに、排気圧力で駆動される過給機(タ
ーボチャージャ)を装着することが検討されているが、
過給機を装着すると、過給機の応答性の悪さによって、
筒内噴射エンジンの大きな利点である加速レスポンスの
良さが損なわれてしまう。[0009] It has been studied to mount a supercharger (turbocharger) driven by exhaust pressure on an in-cylinder injection engine for the purpose of further increasing output and reducing fuel consumption.
When the turbocharger is installed, due to the poor response of the turbocharger,
The great advantage of the in-cylinder injection engine, the good acceleration response, is impaired.
【0010】本発明はこれらの事情を考慮してなされた
ものであり、第1の目的は、追加燃料をスモークを発生
させることなく後燃焼させて排気温度を上昇させ、触媒
を早期に活性化させるようにすることである。The present invention has been made in view of these circumstances, and a first object of the present invention is to post-burn additional fuel without generating smoke to raise the exhaust gas temperature and activate the catalyst early. It is to make it.
【0011】また、第2の目的は、追加燃料の噴射を適
正な時期、適正な噴射量で行うことで、燃費悪化や排気
エミッション悪化を防止しつつ、触媒を早期に活性化さ
せるようにすることである。A second object of the present invention is to activate the catalyst at an early stage by injecting the additional fuel at an appropriate timing and at an appropriate injection amount, thereby preventing deterioration of fuel efficiency and exhaust emission. That is.
【0012】また、第3の目的は、アイドリング時のエ
ンジン振動(ラフネス)低減と触媒の早期活性化とを両
立させるようにすることである。A third object is to achieve both a reduction in engine vibration (roughness) during idling and an early activation of the catalyst.
【0013】また、第4の目的は、リーンNOx触媒に
吸蔵されたNOxを還元浄化するためにリーン運転から
リッチ運転に切り換える際に、トルクショックが発生し
ないようにすることである。A fourth object is to prevent the occurrence of torque shock when switching from lean operation to rich operation in order to reduce and purify NOx stored in the lean NOx catalyst.
【0014】また、第5の目的は、過給機を装着した筒
内噴射式の内燃機関において、加速レスポンスを向上さ
せることである。A fifth object of the present invention is to improve the acceleration response of a direct injection internal combustion engine equipped with a supercharger.
【0015】[0015]
【課題を解決するための手段】前記第1の目的を達成す
るために、本発明の請求項1では、追加燃料噴射制御手
段は、触媒が活性化していない時に、点火後の膨張行程
又は排気行程で1回又は複数回の追加燃料を噴射して該
追加燃料を点火による主燃焼の火炎で後燃焼させること
で排気温度を上昇させて触媒を活性化させる。この際、
ガス流動促進手段は、気筒内のガス流動を促進すること
で、噴射した追加燃料の微粒化をガス流動によって促進
すると共に、追加燃料と気筒内の酸素を含むガスとの混
合攪拌を促進する。これにより、噴射した追加燃料を完
全燃焼させてスモークを発生させることなく、排気温度
を上昇させることができ、スモーク防止と触媒早期活性
化とを両立させることができる。In order to achieve the first object, according to the first aspect of the present invention, the additional fuel injection control means is provided for controlling the post-ignition expansion stroke or the exhaust stroke when the catalyst is not activated. The additional fuel is injected one or more times during the stroke, and the additional fuel is post-combusted with the main combustion flame by ignition, thereby raising the exhaust gas temperature and activating the catalyst. On this occasion,
The gas flow promoting means promotes the gas flow in the cylinder, thereby promoting the atomization of the injected additional fuel by the gas flow and the mixing and stirring of the additional fuel and the gas containing oxygen in the cylinder. This makes it possible to raise the exhaust gas temperature without causing the injected additional fuel to completely combust and generate smoke, thereby achieving both smoke prevention and early catalyst activation.
【0016】この場合、請求項2のように、ガス流動促
進手段として、各気筒に設けられた複数の排気ポートの
うちの1つの排気ポートに配置された排気スワールコン
トロールバルブを用い、追加燃料噴射制御中に排気スワ
ールコントロールバルブを閉じ側に制御するようにして
も良い。排気スワールコントロールバルブを閉じ側に制
御すると、排気行程で、追加燃料が燃焼し始める前に、
気筒内のガス流動にスワールが発生し、このスワールに
よって追加燃料の微粒化が促進されると共に、追加燃料
と筒内ガスとの混合攪拌が促進される。In this case, an exhaust swirl control valve disposed at one of a plurality of exhaust ports provided in each cylinder is used as the gas flow promoting means, and additional fuel injection is performed. During the control, the exhaust swirl control valve may be controlled to close. By controlling the exhaust swirl control valve to the closed side, during the exhaust stroke, before additional fuel starts to burn,
Swirl is generated in the gas flow in the cylinder, and this swirl promotes atomization of the additional fuel and promotes mixing and stirring of the additional fuel and the in-cylinder gas.
【0017】或は、請求項3のように、追加燃料噴射制
御中に排気弁の開弁タイミングを進角側に制御すること
で、気筒内のガス流動を促進させるようにしても良い。
つまり、排気弁の開弁タイミングを進角側に制御する
と、気筒内の燃焼ガスが排出されるタイミングが早ま
り、追加燃料が燃焼し始める前に、気筒内の燃焼ガスの
一部が排気ポートに向けて流動するようになる。これに
より、気筒内のガス流動が促進され、追加燃料の微粒化
が促進されると共に、追加燃料と筒内ガスとの混合攪拌
が促進される。Alternatively, the gas flow in the cylinder may be promoted by controlling the valve opening timing of the exhaust valve to the advanced side during the additional fuel injection control.
In other words, when the valve opening timing of the exhaust valve is controlled to the advanced side, the timing at which the combustion gas in the cylinder is discharged is advanced, and a portion of the combustion gas in the cylinder is discharged to the exhaust port before the additional fuel starts burning. It starts to flow toward. Thereby, the gas flow in the cylinder is promoted, the atomization of the additional fuel is promoted, and the mixing and stirring of the additional fuel and the in-cylinder gas are promoted.
【0018】また、前記第2の目的を達成するために、
請求項4のように、追加燃料の噴射量と噴射時期のいず
れか一方又は両方を、点火前に噴射する主燃料の噴射
量、機関回転数、機関負荷、機関温度、排気温度、排気
行程中の筒内燃焼状態、排気ガス中の酸素濃度の少なく
とも1つに基づいて制御するようにしても良い。つま
り、これらのパラメータは、いずれも追加燃料の燃焼性
に影響を及ぼす(例えば排気ガス中の酸素濃度が高くな
るほど、燃焼可能な追加燃料量は多くなる)。また、点
火による主燃焼の火炎が持続する期間、つまり追加燃料
を燃焼可能な期間も、これらのパラメータによって変化
する。従って、追加燃料の噴射量と噴射時期のいずれか
一方又は両方をこれらのパラメータの少なくとも1つに
よって制御すれば、追加燃料の噴射を適正な時期、適正
な噴射量で行うことが可能となり、燃費悪化や排気エミ
ッション悪化を防止しつつ、触媒を早期に活性化させる
ことができる。In order to achieve the second object,
According to a fourth aspect of the present invention, one or both of the additional fuel injection amount and the injection timing are determined by the injection amount of the main fuel injected before ignition, the engine speed, the engine load, the engine temperature, the exhaust temperature, and during the exhaust stroke. The control may be performed based on at least one of the in-cylinder combustion state and the oxygen concentration in the exhaust gas. That is, these parameters all affect the combustibility of the additional fuel (for example, the higher the oxygen concentration in the exhaust gas, the larger the amount of additional fuel that can be combusted). Further, the period during which the flame of the main combustion by ignition continues, that is, the period during which the additional fuel can be burned, also changes according to these parameters. Therefore, if one or both of the injection amount and the injection timing of the additional fuel are controlled by at least one of these parameters, the injection of the additional fuel can be performed at a proper timing and a proper injection amount, and the fuel consumption can be improved. The catalyst can be activated at an early stage while preventing deterioration and deterioration of exhaust emission.
【0019】また、気筒内で燃料が燃焼する際にイオン
が発生する点に着目し、請求項5のように、気筒内で燃
焼により生じるイオンを点火プラグを通して検出し、そ
のイオン電流に基づいて排気行程中の筒内燃焼状態を燃
焼状態判定手段により判定し、排気行程中の筒内燃焼状
態に基づいて追加燃料の噴射量と噴射時期のいずれか一
方又は両方を制御するようにしても良い。このようにす
れば、点火プラグを利用して排気行程中の筒内燃焼状態
を検出しながら、追加燃料噴射制御を適正化することが
できる。Attention is also paid to the point that ions are generated when fuel is burned in the cylinder, and ions generated by combustion in the cylinder are detected through a spark plug as described in claim 5, and based on the ion current, The in-cylinder combustion state during the exhaust stroke may be determined by the combustion state determination means, and one or both of the injection amount and the injection timing of the additional fuel may be controlled based on the in-cylinder combustion state during the exhaust stroke. . This makes it possible to optimize the additional fuel injection control while detecting the in-cylinder combustion state during the exhaust stroke using the ignition plug.
【0020】また、前記第3の目的を達成するために、
請求項6のように、燃焼方式切換手段によって、アイド
リング時の燃焼方式を、機関温度、排気温度、触媒温度
の少なくとも1つに基づいて成層燃焼と均質燃焼との間
で切り換えるようにしても良い。このようにすれば、例
えば、エンジンが暖機されていない冷間時のようにエン
ジンフリクションが高い状態の時には、均質燃焼方式に
切り換えて、吸気行程で燃料を噴射して均質燃焼させる
ことで、燃焼状態を安定させることができ、アイドリン
グ時のエンジン振動(ラフネス)を低減することができ
る。In order to achieve the third object,
According to a sixth aspect, the combustion mode switching means may switch the combustion mode during idling between stratified combustion and homogeneous combustion based on at least one of the engine temperature, the exhaust gas temperature, and the catalyst temperature. . By doing so, for example, when the engine friction is high, such as during a cold time when the engine is not warmed up, by switching to the homogeneous combustion method, fuel is injected in the intake stroke to perform homogeneous combustion, The combustion state can be stabilized, and engine vibration (roughness) during idling can be reduced.
【0021】また、請求項7のように、排気残留量制御
手段によって排気スワールコントロールバルブの開度を
制御することで筒内排気残留量(内部EGR量)を制御
するようにしても良い。このようにすれば、排気スワー
ルコントロールバルブの開度を制御することで、内部E
GR(内部排気ガス再循環)を実現でき、この内部EG
Rと触媒との組み合わせで排気浄化性能を向上できると
共に、外部のEGR装置を廃止することが可能となり、
コスト低減にもつながる。Further, the in-cylinder exhaust residual amount (internal EGR amount) may be controlled by controlling the opening of the exhaust swirl control valve by the exhaust residual amount control means. In this way, by controlling the opening of the exhaust swirl control valve, the internal E
GR (internal exhaust gas recirculation) can be realized.
Exhaust gas purification performance can be improved by combining R and a catalyst, and an external EGR device can be eliminated,
It also leads to cost reduction.
【0022】また、前記第4の目的を達成するために、
請求項8のように、リーンNOx触媒に吸蔵されている
NOxを還元浄化する際に、点火後の膨張行程又は排気
行程で1回又は複数回の追加燃料を噴射して該追加燃料
を点火による主燃焼の火炎で後燃焼させることで排気ガ
スの空燃比をリッチ又は理論空燃比に切り換えるように
しても良い。つまり、点火後に噴射した追加燃料は、燃
焼してもエンジン出力があまり変化しないため、NOx
を還元浄化する際に、追加燃料の噴射によってリッチ運
転に切り換えれば、トルクショックを伴わずにリーン運
転からリッチ運転に切り換えることができ、ドライバビ
リティを向上することができる。In order to achieve the fourth object,
When reducing and purifying NOx stored in the lean NOx catalyst, one or more times of additional fuel is injected during the expansion stroke or the exhaust stroke after ignition to cause the additional fuel to be ignited. The air-fuel ratio of the exhaust gas may be switched to a rich or stoichiometric air-fuel ratio by post-combustion with the main combustion flame. In other words, the additional fuel injected after the ignition does not change much when the engine is burned.
If the operation is switched to the rich operation by the injection of the additional fuel at the time of the reduction purification, the operation can be switched from the lean operation to the rich operation without a torque shock, and the drivability can be improved.
【0023】また、前記第5の目的を達成するために、
請求項9のように、排気圧力によって駆動される過給機
を装着し、加速時に、点火後の膨張行程又は排気行程で
1回又は複数回の追加燃料を噴射して該追加燃料を点火
による主燃焼の火炎で後燃焼させることで排気圧力を上
昇させて過給機の応答性を向上させるようにしても良
い。このようにすれば、筒内噴射式の内燃機関の大きな
利点である加速レスポンスの良さを損なわずに、過給機
によって更なる高出力化、省燃費化を実現することがで
きる。In order to achieve the fifth object,
According to a ninth aspect of the present invention, a supercharger driven by exhaust pressure is mounted, and at the time of acceleration, one or more times of additional fuel is injected during an expansion stroke or an exhaust stroke after ignition to ignite the additional fuel. The post-combustion with the flame of the main combustion may raise the exhaust pressure to improve the responsiveness of the supercharger. In this manner, the turbocharger can further increase the output and reduce the fuel consumption without deteriorating the acceleration response, which is a great advantage of the direct injection internal combustion engine.
【0024】[0024]
【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。筒内噴射式の内燃機関である筒内噴
射エンジン11の吸気管12の最上流部には、エアクリ
ーナ13が設けられ、このエアクリーナ13の下流側
に、吸入空気量を計測するエアフローメータ14が設け
られている。吸気管12の途中部には、スロットルバル
ブ(図示せず)を内蔵したスロットルボディ15が設け
られ、このスロットルボディ15には、スロットル開度
を検出するスロットル開度センサ16と、スロットルバ
ルブを駆動するアクチュエータ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 13 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, and an air flow meter 14 for measuring an intake air amount is provided downstream of the air cleaner 13. Have been. A throttle body 15 having a built-in throttle valve (not shown) is provided at an intermediate portion of the intake pipe 12. The throttle body 15 has a throttle opening sensor 16 for detecting a throttle opening and a drive for the throttle valve. Actuator 17 is provided.
【0025】エンジン11の各気筒には、2つの吸気ポ
ート18a,18bと2つの排気ポート19a,19b
が設けられている。そのうち、片方の吸気ポート18a
には吸気スワールコントロールバルブ(以下「吸気SC
V」と表記する)20が設けられ、また、片方の排気ポ
ート19aには、排気スワールコントロールバルブ(以
下「排気SCV」と表記する)21が設けられている。
更に、エンジン11の各気筒には、燃料噴射弁22と点
火プラグ23が設けられ、クランク角を検出するクラン
ク角センサ24と、気筒を判別するための基準位置を検
出する気筒判別センサ25と、エンジン冷却水温を検出
する水温センサ26と、各気筒の排気弁(図示せず)の
開弁タイミングを変更する排気弁開弁タイミング変更装
置27が設けられている。Each cylinder of the engine 11 has two intake ports 18a, 18b and two exhaust ports 19a, 19b.
Is provided. One of the intake ports 18a
Has an intake swirl control valve (hereinafter referred to as "intake SC
V), and an exhaust port 19a is provided with an exhaust swirl control valve (hereinafter, referred to as “exhaust SCV”) 21.
Further, each cylinder of the engine 11 is provided with a fuel injection valve 22 and a spark plug 23, a crank angle sensor 24 for detecting a crank angle, a cylinder discrimination sensor 25 for detecting a reference position for discriminating a cylinder, A water temperature sensor 26 for detecting an engine cooling water temperature and an exhaust valve opening timing changing device 27 for changing the opening timing of an exhaust valve (not shown) of each cylinder are provided.
【0026】点火プラグ23は、点火コイル28の二次
巻線側に接続され、点火コイル28の一次巻線側には、
後述する電子制御ユニット36によって制御されるイグ
ナイタ29が接続されている。エンジン運転中は、点火
タイミング毎にイグナイタ29で点火コイル28の一次
電流を遮断することで、点火コイル28の二次側に高電
圧を発生させて、この高電圧を点火プラグ23に印加
し、火花放電を発生させる。The ignition plug 23 is connected to the secondary winding side of the ignition coil 28, and the primary winding side of the ignition coil 28
An igniter 29 controlled by an electronic control unit 36 described later is connected. During engine operation, the igniter 29 cuts off the primary current of the ignition coil 28 at each ignition timing, thereby generating a high voltage on the secondary side of the ignition coil 28, and applying this high voltage to the ignition plug 23, Generates spark discharge.
【0027】一方、排気管30には、排気ガス温度を検
出する排気温度センサ31と、排気ガス中の酸素濃度を
検出する酸素センサ32が設けられ、これらのセンサ3
1,32の下流側に、NOx吸蔵型のリーンNOx触媒
33が設けられている。このリーンNOx触媒33に
は、触媒温度を検出する触媒温度センサ34が設けられ
ている。リーンNOx触媒33の下流側にはマフラ35
が取り付けられている。On the other hand, the exhaust pipe 30 is provided with an exhaust gas temperature sensor 31 for detecting the temperature of the exhaust gas and an oxygen sensor 32 for detecting the concentration of oxygen in the exhaust gas.
A NOx storage type lean NOx catalyst 33 is provided downstream of the NOx catalysts 1 and 32. The lean NOx catalyst 33 is provided with a catalyst temperature sensor 34 for detecting a catalyst temperature. A muffler 35 is provided downstream of the lean NOx catalyst 33.
Is attached.
【0028】上述した各種のセンサの出力信号は、電子
制御ユニット(以下「ECU」と表記する)36内に取
り込まれる。このECU36は、CPU37、RAM3
8、ROM39(記憶媒体)、入力インターフェース4
0、出力インターフェース41等を備えたマイクロコン
ピュータにより構成され、更に、上述した燃料噴射弁2
2等の各種のアクチュエータを駆動するための駆動回路
42,43が内蔵されている。このECU36は、RO
M39に記憶された燃料噴射制御プログラムや点火制御
プログラムをCPU37で実行することで、燃料噴射制
御、点火制御を行う。The output signals of the various sensors described above are taken into an electronic control unit (hereinafter referred to as “ECU”) 36. The ECU 36 includes a CPU 37, a RAM 3
8, ROM39 (storage medium), input interface 4
0, a microcomputer having an output interface 41 and the like.
Drive circuits 42 and 43 for driving various actuators such as 2 are built in. This ECU 36
The CPU 37 executes the fuel injection control program and the ignition control program stored in M39 to perform the fuel injection control and the ignition control.
【0029】このECU36は、ROM39に記憶され
た後述する図2乃至図4のプログラムをCPU37で実
行することで、リーンNOx触媒33が活性化していな
い時(つまり触媒温度が活性下限温度αよりも低い時)
に、点火後の膨張行程又は排気行程で追加燃料を噴射し
て該追加燃料を点火による主燃焼の火炎で後燃焼させる
ことで排気温度を上昇させてリーンNOx触媒33を活
性化させる追加燃料噴射制御手段として機能すると共
に、追加燃料噴射制御中に排気SCV21を閉じ側に制
御すると同時に、排気弁(図示せず)の開弁タイミング
を排気弁開弁タイミング変更装置27によって進角側に
制御することで、気筒内のガス流動を促進して追加燃料
の後燃焼を促進するガス流動促進手段としても機能す
る。尚、本実施形態(1)では、排気SCV21は、通
常時に全開とし、追加燃料噴射を行う時に全閉に切り換
える2段階制御を行い、また、排気弁の開弁タイミング
は、通常時に最遅角とし、追加燃料噴射を行う時に最進
角に切り換える2段階制御を行う。When the lean NOx catalyst 33 is not activated (that is, when the catalyst temperature is lower than the activation lower limit temperature α), the ECU 36 executes the program shown in FIGS. When low)
In addition, additional fuel is injected in the expansion stroke or the exhaust stroke after ignition, and the additional fuel is post-combusted with the flame of the main combustion by ignition to raise the exhaust gas temperature and activate the lean NOx catalyst 33. In addition to functioning as a control means, the exhaust SCV 21 is controlled to be closed during the additional fuel injection control, and at the same time, the opening timing of an exhaust valve (not shown) is controlled to be advanced by the exhaust valve opening timing changing device 27. This also functions as a gas flow promoting unit that promotes gas flow in the cylinder and promotes post combustion of the additional fuel. In the present embodiment (1), the exhaust SCV 21 is fully opened during normal operation and performs two-stage control of switching to fully closed when performing additional fuel injection, and the exhaust valve opening timing is normally the most retarded. When the additional fuel injection is performed, two-stage control for switching to the most advanced angle is performed.
【0030】以下、これらの制御を行う図2乃至図4の
プログラムの処理内容を説明する。図2及び図3に示す
アイドル制御プログラムは、スロットル開度VA、エン
ジン回転数NE等に基づいてアイドル安定状態と判断さ
れる期間中に所定時間毎に繰り返し実行される。本プロ
グラムが起動されると、まずステップ101で、各種セ
ンサで検出されたエンジン回転数NE、スロットル開度
VA、吸入空気量QA、冷却水温Thw、排気温度Th
e、触媒温度Thc等のエンジン運転状態の検出信号を
読み込む。Hereinafter, the processing contents of the programs shown in FIGS. 2 to 4 for performing these controls will be described. The idle control program shown in FIGS. 2 and 3 is repeatedly executed at predetermined time intervals during a period in which the idle state is determined based on the throttle opening VA, the engine speed NE, and the like. When the program is started, first, in step 101, the engine speed NE, the throttle opening VA, the intake air amount QA, the cooling water temperature Thw, and the exhaust gas temperature Th detected by various sensors.
e) Read the detection signal of the engine operating state such as the catalyst temperature Thc.
【0031】この後、ステップ102で、触媒温度セン
サ34で検出した触媒温度Thcに基づいてリーンNO
x触媒33の活性状態を判定し、触媒温度Thcが活性
下限温度α以下であれば、リーンNOx触媒33が排気
ガスを十分に浄化できない状態、つまり未活性状態と判
断する。この場合には、追加燃料噴射による排気ガスの
昇温が必要と判断し、ステップ103に進み、追加燃料
噴射実施フラグFwpiを“追加燃料噴射実施”を意味
する“1”にセットすると共に、燃焼方式フラグFco
mを成層燃焼を意味する“S”にセットし、燃焼方式を
成層燃焼に切り換える。ここで、追加燃料噴射を実施す
る際に、燃焼方式を成層燃焼に切り換える理由は、点火
後に噴射した追加燃料を主燃焼の火炎で後燃焼させるた
めには、主燃焼終了時に酸素が残っていることが必要で
あり、そのために、主燃焼をリーン混合気による成層燃
焼とすることで、主燃焼終了時に酸素を残すようにする
ものである。Thereafter, in step 102, the lean NO is determined based on the catalyst temperature Thc detected by the catalyst temperature sensor 34.
The activation state of the x catalyst 33 is determined, and if the catalyst temperature Thc is equal to or lower than the activation lower limit temperature α, it is determined that the lean NOx catalyst 33 cannot sufficiently purify the exhaust gas, that is, an inactive state. In this case, it is determined that the temperature of the exhaust gas needs to be increased by the additional fuel injection, and the routine proceeds to step 103, where the additional fuel injection execution flag Fwpi is set to "1" meaning "additional fuel injection", and the combustion is performed. Method flag Fco
m is set to “S” meaning stratified combustion, and the combustion mode is switched to stratified combustion. Here, when performing the additional fuel injection, the reason for switching the combustion method to the stratified charge combustion is that oxygen is left at the end of the main combustion in order to post-burn the additional fuel injected after the ignition with the flame of the main combustion. Therefore, the main combustion is performed by stratified combustion using a lean air-fuel mixture so that oxygen is left at the end of the main combustion.
【0032】更に、追加燃料噴射を実施する場合には、
燃焼が不安定となりやすいため、アイドルアップが必要
と判断し、ステップ107に進み、アイドル目標回転数
Nltarget を高い方のアイドル回転数Naに切り換え
る。Further, when performing additional fuel injection,
Since the combustion tends to be unstable, it is determined that the idle-up is necessary, and the routine proceeds to step 107, where the idle target rotational speed Nltarget is switched to the higher idle rotational speed Na.
【0033】一方、前記ステップ102で、触媒温度T
hcが活性下限温度αよりも高い場合には、リーンNO
x触媒33が活性化されていると判断して、ステップ1
04に進み、追加燃料噴射実施フラグFwpiを“追加
燃料噴射実施せず”を意味する“0”にセットする。こ
の後、ステップ105で、水温センサ26で検出した冷
却水温Thwに基づいてエンジン暖機状態を判断する。
もし、冷却水温Thwが比較的低い温度に設定された所
定温度β1以下であれば、冷機状態と判断してステップ
106に進み、燃焼方式フラグFcomを均質燃焼を意
味する“H”にセットして、燃焼方式を冷機状態でも安
定燃焼しやすい均質燃焼に切り換える。この場合でも、
追加燃料噴射実施時と同じく、アイドルアップが必要と
判断してステップ107に進み、アイドル目標回転数N
ltarget を高い方のアイドル回転数Naに切り換える。On the other hand, at step 102, the catalyst temperature T
When hc is higher than the activity lower limit temperature α, the lean NO
When it is determined that the x catalyst 33 is activated,
In step 04, the additional fuel injection execution flag Fwpi is set to "0" which means "no additional fuel injection is performed". Thereafter, in step 105, the engine warm-up state is determined based on the cooling water temperature Thw detected by the water temperature sensor 26.
If the cooling water temperature Thw is equal to or lower than the predetermined temperature β1 set to a relatively low temperature, it is determined that the engine is in a cold state, and the routine proceeds to step 106, where the combustion mode flag Fcom is set to “H” meaning homogeneous combustion. In addition, the combustion method is switched to homogeneous combustion that facilitates stable combustion even in a cold state. Even in this case,
As in the case of performing the additional fuel injection, it is determined that the idle-up is necessary, and the routine proceeds to step 107, where the target idle speed N
Switch ltarget to the higher idle speed Na.
【0034】また、前記ステップ105で、冷却水温T
hwが所定温度β1よりも高いと判断された場合には、
燃焼が比較的安定していると判断して、ステップ108
に進み、アイドル目標回転数Nltarget を低い方のアイ
ドル回転数Nb(但しNb<Na)に切り換える。そし
て、次のステップ109で、冷却水温Thwを基に再度
エンジン暖機状態を判断し、冷却水温Thwが比較的高
い温度に設定された所定温度β2(但しβ2>β1)以
上であれば、エンジン11が完全暖機状態であると判断
して、ステップ110に進み、燃焼方式フラグFcom
を成層燃焼を意味する“S”にセットして、燃焼方式を
燃費の良い成層燃焼に切り換える。In step 105, the cooling water temperature T
If hw is determined to be higher than the predetermined temperature β1,
If it is determined that the combustion is relatively stable, step 108
The target idle speed Nltarget is switched to the lower idle speed Nb (where Nb <Na). Then, in the next step 109, the engine warm-up state is determined again based on the cooling water temperature Thw, and if the cooling water temperature Thw is equal to or higher than a predetermined temperature β2 (where β2> β1) set to a relatively high temperature, the engine is started. 11 is determined to be in a completely warmed-up state, the routine proceeds to step 110, and the combustion mode flag Fcom
Is set to “S” meaning stratified combustion, and the combustion method is switched to stratified combustion with good fuel efficiency.
【0035】一方、上記ステップ109で、冷却水温T
hwが所定温度β2よりも低いと判断された場合(β1
<Thw<β2の場合)には、エンジン11が暖機途中
であると判断して、ステップ111に進み、燃焼方式フ
ラグFcomを均質燃焼を意味する“H”にセットし
て、燃焼方式を暖機途中でも安定燃焼する均質燃焼に切
り換える。これらステップ103,106,110,1
11で燃焼方式を切り換える処理は、特許請求の範囲で
いう燃焼方式切換手段としての役割を果たす。On the other hand, at step 109, the cooling water temperature T
hw is determined to be lower than the predetermined temperature β2 (β1
If <Thw <β2), it is determined that the engine 11 is in the process of warming up, and the routine proceeds to step 111, where the combustion mode flag Fcom is set to “H” meaning homogeneous combustion, and the combustion mode is set to the warm-up mode. Switch to homogeneous combustion for stable combustion even in the middle of the machine. These steps 103, 106, 110, 1
The process of switching the combustion mode in step 11 serves as the combustion mode switching means in the claims.
【0036】以上のようにして、リーンNOx触媒33
の活性状態とエンジン暖機状態とに基づいて、追加燃料
噴射実施の有無、燃焼方式、アイドル目標回転数Nltar
getを設定した後、図3のステップ112に進み、点火
前に噴射する主燃料の噴射量(主噴射量)、主燃料の噴
射時期(主噴射時期)、点火時期を算出する。As described above, the lean NOx catalyst 33
Of the additional fuel injection, the combustion method, the idle target rotation speed Nltar
After setting get, the process proceeds to step 112 in FIG. 3, and the main fuel injection amount (main injection amount) to be injected before ignition, the main fuel injection timing (main injection timing), and the ignition timing are calculated.
【0037】ここで、主噴射量Ti1を算出する場合
は、まず、エンジン回転数NE、エンジン負荷等のエン
ジン運転状態に応じてマップ等より基本燃料噴射量Tp
を算出し、冷却水温補正係数、空燃比フィードバック補
正係数等の各種の補正係数Fcと、バッテリ電圧によっ
て変化する燃料噴射弁22の応答遅れ時間を補正するた
めの無効噴射量Tvとを用いて次式により主噴射量Ti
1を算出する。 Ti1=Tp×Fc+TvHere, when calculating the main injection amount Ti1, first, the basic fuel injection amount Tp is calculated from a map or the like according to the engine operating state such as the engine speed NE and the engine load.
Is calculated using various correction coefficients Fc such as a cooling water temperature correction coefficient and an air-fuel ratio feedback correction coefficient, and an invalid injection amount Tv for correcting a response delay time of the fuel injection valve 22 that changes according to a battery voltage. From the formula, the main injection amount Ti
1 is calculated. Ti1 = Tp × Fc + Tv
【0038】また、主噴射時期を算出する場合は、燃焼
方式に応じて、エンジン回転数NEと基本燃料噴射量T
pとを基にマップ等により主噴射時期を算出する。この
主噴射時期は、成層燃焼の場合には噴射終了時期として
設定し、均質燃焼の場合には噴射開始時期として設定す
る。When calculating the main injection timing, the engine speed NE and the basic fuel injection amount T are determined according to the combustion method.
The main injection timing is calculated based on p and a map or the like. This main injection timing is set as the injection end timing in the case of stratified combustion, and is set as the injection start timing in the case of homogeneous combustion.
【0039】また、点火時期を算出する場合は、まず、
エンジン回転数NEと基本燃料噴射量Tpに応じてマッ
プ等により基本点火時期を算出し、この基本点火時期を
冷却水温等で補正して、最終的な点火時期を算出する。When calculating the ignition timing, first,
The basic ignition timing is calculated by a map or the like according to the engine speed NE and the basic fuel injection amount Tp, and the basic ignition timing is corrected by the cooling water temperature or the like to calculate the final ignition timing.
【0040】以上のようにして主噴射量、主噴射時期、
点火時期を算出した後、ステップ113に進み、追加燃
料噴射実施フラグFwpiが“追加燃料噴射実施”を意
味する“1”であるか否かを判定し、Fwpi=“0”
(追加燃料噴射実施せず)の場合には、ステップ117
に進み、排気SCV21の弁開度を100%(全開)に
設定すると共に、排気弁の開弁タイミングを最遅角に設
定し、排気性能を優先した制御とする。As described above, the main injection amount, the main injection timing,
After calculating the ignition timing, the routine proceeds to step 113, where it is determined whether or not the additional fuel injection execution flag Fwpi is “1” meaning “additional fuel injection is performed”, and Fwpi = “0”.
In the case of (no additional fuel injection is performed), step 117
Then, the valve opening of the exhaust SCV 21 is set to 100% (fully open), the valve opening timing of the exhaust valve is set to the most retarded angle, and the control is performed with priority given to the exhaust performance.
【0041】一方、ステップ113で、Fwpi=
“1”(追加燃料噴射実施)の場合には、ステップ11
4に進み、図4の追加燃料噴射量・噴射時期算出プログ
ラムを実行して、追加燃料の噴射量(追加噴射量Ti
2)と追加燃料の噴射時期(追加噴射時期θ2)を次の
ようにして算出する。まず、ステップ201で、基本追
加噴射量Qbaseを主噴射量Ti1によるマップ補間
にて算出する。この場合、主噴射量Ti1が少なくなる
ほど、主燃焼終了時の酸素の残存量が多くなることを考
慮して、主噴射量Ti1が少なくなるほど、基本追加噴
射量Qbaseを増加させる。On the other hand, at step 113, Fwpi =
If “1” (additional fuel injection is performed), step 11
4 and execute the additional fuel injection amount / injection timing calculation program of FIG. 4 to execute the additional fuel injection amount (additional injection amount Ti
2) and the additional fuel injection timing (additional injection timing θ2) are calculated as follows. First, in step 201, the basic additional injection amount Qbase is calculated by map interpolation using the main injection amount Ti1. In this case, considering that the main injection amount Ti1 decreases and the remaining amount of oxygen at the end of the main combustion increases, the basic additional injection amount Qbase increases as the main injection amount Ti1 decreases.
【0042】この後、ステップ202で、酸素センサ3
2で検出した排気酸素濃度O2 に基づいて、基本追加噴
射量Qbaseに対する残存酸素量補正量Qcoを次式
により算出する。 Qco(i) =Qco(i-1) +(O2 −Ko)×CoThereafter, at step 202, the oxygen sensor 3
Based on the exhaust oxygen concentration O2 detected in step 2, the residual oxygen amount correction amount Qco for the basic additional injection amount Qbase is calculated by the following equation. Qco (i) = Qco (i-1) + (O2 -Ko) .times.Co
【0043】上式において、Qco(i) は今回の残存酸
素量補正量、Qco(i-1) は前回の残存酸素量補正量、
Koは基準酸素濃度、Coは補正係数である。例えば、
排気酸素濃度O2 が基準酸素濃度Koよりも高い場合に
は、排気酸素濃度O2 と基準酸素濃度Koとの差に応じ
た補正量(O2 −Ko)×Coによって残存酸素量補正
量Qcoを増量する。反対に、排気酸素濃度O2 が基準
酸素濃度Koよりも低い場合には、排気酸素濃度O2 と
基準酸素濃度Koとの差に応じた補正量(O2−Ko)
×Coによって残存酸素量補正量Qcoを減量する。In the above equation, Qco (i) is the current residual oxygen amount correction amount, Qco (i-1) is the previous residual oxygen amount correction amount,
Ko is a reference oxygen concentration, and Co is a correction coefficient. For example,
When the exhaust oxygen concentration O2 is higher than the reference oxygen concentration Ko, the residual oxygen amount correction amount Qco is increased by a correction amount (O2-Ko) × Co according to the difference between the exhaust oxygen concentration O2 and the reference oxygen concentration Ko. . Conversely, when the exhaust oxygen concentration O2 is lower than the reference oxygen concentration Ko, the correction amount (O2 -Ko) corresponding to the difference between the exhaust oxygen concentration O2 and the reference oxygen concentration Ko
The residual oxygen amount correction amount Qco is reduced by × Co.
【0044】次のステップ203で、基本追加噴射量Q
baseに残存酸素量補正量Qcoを加算して、追加噴
射量Ti2を求める。 Ti2=Qbase+Qco 但し、Qbase+Qcoが着火可能な最少噴射量Qm
inより少ない場合には、追加噴射量Ti2は、着火可
能な最少噴射量Qminでガード処理されて、Ti2=
Qminとなり、Qbase+Qcoが最少噴射量Qm
in以上の場合には、Ti2=Qbase+Qcoとな
る。In the next step 203, the basic additional injection amount Q
The additional injection amount Ti2 is obtained by adding the residual oxygen amount correction amount Qco to the base. Ti2 = Qbase + Qco, where Qbase + Qco is the minimum injection quantity Qm at which ignition is possible
If it is less than in, the additional injection amount Ti2 is subjected to guard processing with the minimum ignitable injection amount Qmin, and Ti2 =
Qmin, and Qbase + Qco is the minimum injection amount Qm
In the case of in or more, Ti2 = Qbase + Qco.
【0045】追加噴射量Ti2の算出後、ステップ20
4に進み、基本追加噴射時期θbaseを主噴射量Ti
1によるマップ補間にて算出する。この場合、主噴射量
Ti1が多くなるほど、主燃焼の火炎が長く持続するこ
とを考慮し、主噴射量Ti1が多くなるほど、基本追加
噴射時期θbaseを遅角させる。After calculating the additional injection amount Ti2, step 20
4, the basic additional injection timing θbase is changed to the main injection amount Ti
1 is calculated by map interpolation. In this case, considering that the flame of main combustion lasts longer as the main injection amount Ti1 increases, the basic additional injection timing θbase is retarded as the main injection amount Ti1 increases.
【0046】次のステップ205で、排気行程中の気筒
内のイオン残存時期Tiを検出し、このイオン残存時期
Tiに基づいて基本追加噴射時期θbaseに対するイ
オン残存時期補正量θcを算出する。排気行程中の気筒
内のイオン検出は、点火後の点火プラグ23に定電圧を
印加して、点火プラグ23の電極のギャップに存在する
ガス中のイオンをプラグ電極で集め、プラグ電極に流れ
るイオン電流を検出する。そして、イオン検出可能な最
終時期をイオン残存時期Tiとし、次式によりイオン残
存時期補正量θcを算出する。 θc(i) =θc(i-1) +(Ti−Ki)×CiIn the next step 205, the ion remaining timing Ti in the cylinder during the exhaust stroke is detected, and the ion remaining timing correction amount θc for the basic additional injection timing θbase is calculated based on the ion remaining timing Ti. Detection of ions in the cylinder during the exhaust stroke is performed by applying a constant voltage to the ignition plug 23 after ignition, collecting ions in the gas present in the gap between the electrodes of the ignition plug 23 at the plug electrode, and detecting ions flowing through the plug electrode. Detect the current. Then, the last time at which ions can be detected is defined as the ion remaining time Ti, and the ion remaining time correction amount θc is calculated by the following equation. θc (i) = θc (i−1) + (Ti−Ki) × Ci
【0047】上式において、θc(i) は今回のイオン残
存時期補正量、θc(i-1) は前回のイオン残存時期補正
量、Kiは基準イオン残存時期、Ciは補正係数であ
る。例えば、イオン残存時期Tiが基準イオン残存時期
Kiよりも遅い場合には、イオン残存時期Tiと基準イ
オン残存時期Kiとの差に応じた補正量(Ti−Ki)
×Ciによってイオン残存時期補正量θcを大きくする
(これにより追加噴射時期θ2を遅角させる)。反対
に、イオン残存時期Tiが基準イオン残存時期Kiより
も前に終わる場合には、イオン残存時期Tiと基準イオ
ン残存時期Kiとの差に応じた補正量(Ti−Ki)×
Ciによってイオン残存時期補正量θcを小さくする
(これにより追加噴射時期θ2を進角させる)。In the above equation, θc (i) is the current ion remaining time correction amount, θc (i-1) is the previous ion remaining time correction amount, Ki is the reference ion remaining time, and Ci is the correction coefficient. For example, when the ion remaining time Ti is later than the reference ion remaining time Ki, the correction amount (Ti-Ki) according to the difference between the ion remaining time Ti and the reference ion remaining time Ki.
The amount of correction of remaining ion timing θc is increased by × Ci (the additional injection timing θ2 is thereby retarded). On the other hand, when the ion remaining time Ti ends before the reference ion remaining time Ki, the correction amount (Ti−Ki) × the difference according to the difference between the ion remaining time Ti and the reference ion remaining time Ki.
The amount of correction of the ion remaining timing θc is reduced by Ci (the additional injection timing θ2 is advanced).
【0048】イオン残存時期補正量θcの算出後、ステ
ップ206に進み、基本追加噴射時期θbaseにイオ
ン残存時期補正量θcを加算して追加噴射時期θ2を算
出する。 θ2=θbase+θcAfter calculating the ion residual timing correction amount θc, the routine proceeds to step 206, where the ion residual timing correction amount θc is added to the basic additional injection timing θbase to calculate the additional injection timing θ2. θ2 = θbase + θc
【0049】以上のようにして、追加噴射量Ti2と追
加噴射時期θ2を算出した後、図3のステップ115に
戻り、排気SCV21の弁開度を算出して、排気SCV
21を閉じ側(例えば全閉)に制御する。これにより、
排気行程で、追加燃料が燃焼し始める前に、気筒内のガ
ス流動にスワールが発生し、このスワールによって追加
燃料の微粒化が促進されると共に、追加燃料と筒内ガス
との混合攪拌が促進される。After calculating the additional injection amount Ti2 and the additional injection timing θ2 as described above, the routine returns to step 115 in FIG. 3, and the valve opening of the exhaust SCV 21 is calculated to obtain the exhaust SCV.
21 is controlled to the closing side (for example, fully closed). This allows
In the exhaust stroke, before the additional fuel starts burning, swirl is generated in the gas flow in the cylinder, and this swirl promotes atomization of the additional fuel and promotes mixing and stirring of the additional fuel and the in-cylinder gas. Is done.
【0050】更に、次のステップ116で、排気弁の開
弁タイミングを算出し、開弁タイミングを進角側(例え
ば最進角)に制御する。これにより、気筒内の燃焼ガス
が排出されるタイミングが早まり、追加燃料が燃焼し始
める前に、気筒内の燃焼ガスの一部が片方の排気ポート
19bに向けて流動し始め、上述した排気SCV21に
よるスワール発生効果と相俟って気筒内のガス流動が効
果的に促進され、追加燃料の微粒化が促進されると共
に、追加燃料と筒内ガスとの混合攪拌が促進される。Further, in the next step 116, the valve opening timing of the exhaust valve is calculated, and the valve opening timing is controlled to the advanced side (for example, the most advanced angle). As a result, the timing at which the combustion gas in the cylinder is discharged is advanced, and before the additional fuel starts burning, a part of the combustion gas in the cylinder starts flowing toward one exhaust port 19b, and the above-described exhaust SCV 21 The gas flow in the cylinder is effectively promoted in combination with the swirl generation effect by the above, and the atomization of the additional fuel is promoted, and the mixing and stirring of the additional fuel and the gas in the cylinder are promoted.
【0051】以上説明したアイドル制御プログラムによ
って行われる主燃料、追加燃料の噴射制御の例を図5を
用いて説明する。点火時期は、燃焼方式に拘らず、圧縮
行程の終わりに近い時期に設定される。均質燃焼では、
例1のように、吸気行程で主燃料を噴射して、点火時期
までに気筒内に均質混合気を形成し、成層燃焼では、例
2のように、圧縮行程で主燃料を噴射して、点火プラグ
23の近傍部分を局部的に濃い混合比とする成層混合気
を形成する。また、例3は、主燃料の噴射を2回に分け
て実施する例であり、吸気行程と圧縮行程にそれぞれ主
燃料の噴射を1回ずつ行う。尚、主燃料の噴射を3回以
上に分けて実施しても良い。An example of the main fuel and additional fuel injection control performed by the idle control program described above will be described with reference to FIG. The ignition timing is set to a timing near the end of the compression stroke regardless of the combustion method. In homogeneous combustion,
As in Example 1, the main fuel is injected in the intake stroke to form a homogeneous mixture in the cylinder by the ignition timing. In the stratified combustion, as in Example 2, the main fuel is injected in the compression stroke. A stratified mixture is formed in which a portion near the spark plug 23 has a locally high mixture ratio. Example 3 is an example in which the injection of the main fuel is divided into two times, and the main fuel is injected once each in the intake stroke and the compression stroke. The main fuel injection may be performed three or more times.
【0052】一方、追加燃料の噴射は、例4、例5、例
6に示すように、点火後の膨張行程又は排気行程で1回
又は複数回行えば良い。尚、図2〜図4のプログラムで
は、膨張行程又は排気行程で追加燃料の噴射は1回のみ
行われる(例4、例5)。On the other hand, as shown in Examples 4, 5, and 6, the additional fuel may be injected one or more times in the expansion stroke or the exhaust stroke after ignition. In addition, in the program of FIGS. 2 to 4, the injection of the additional fuel is performed only once in the expansion stroke or the exhaust stroke (Examples 4 and 5).
【0053】以上説明した本実施形態(1)では、リー
ンNOx触媒33が活性化していない時(つまり触媒温
度が活性下限温度αよりも低い時)に、点火後の膨張行
程又は排気行程で追加燃料を噴射して該追加燃料を主燃
焼の火炎で後燃焼させることで排気温度を上昇させてリ
ーンNOx触媒33を活性化させる。In the embodiment (1) described above, when the lean NOx catalyst 33 is not activated (that is, when the catalyst temperature is lower than the activation lower limit temperature α), additional fuel is added in the expansion stroke or the exhaust stroke after ignition. The fuel is injected and the additional fuel is post-combusted with the main combustion flame to raise the exhaust gas temperature and activate the lean NOx catalyst 33.
【0054】そして、この追加燃料噴射制御中は、排気
SCV21を閉じ側に制御して、排気行程中に気筒内の
ガス流動にスワールを発生させながら、排気弁の開弁タ
イミングを進角側に制御して、気筒内の燃焼ガスの一部
を片方の排気ポート19bに向けて流動させるので、追
加燃料が燃焼し始める前に、気筒内のガス流動を効果的
に促進することができ、このガス流動により追加燃料の
微粒化を促進することができると共に、追加燃料と筒内
ガスとの混合攪拌も促進することができる。これによ
り、噴射した追加燃料を完全燃焼させてスモークを発生
させることなく、排気温度を上昇させることができ、ス
モーク防止と触媒早期活性化とを両立させることができ
る。During the additional fuel injection control, the exhaust SCV 21 is controlled to the closed side, and while the gas flow in the cylinder is swirled during the exhaust stroke, the exhaust valve opening timing is advanced. By controlling the flow of a part of the combustion gas in the cylinder toward one exhaust port 19b, the gas flow in the cylinder can be effectively promoted before the additional fuel starts to be burned. The atomization of the additional fuel can be promoted by the gas flow, and the mixing and stirring of the additional fuel and the in-cylinder gas can be promoted. This makes it possible to raise the exhaust gas temperature without causing the injected additional fuel to completely combust and generate smoke, thereby achieving both smoke prevention and early catalyst activation.
【0055】尚、本実施形態(1)では、追加燃料噴射
制御中に、排気SCV21を閉じ側に制御し、且つ、排
気弁の開弁タイミングを進角側に制御するようにした
が、いずれか一方のみを行うようにしても良く、この場
合でも、気筒内のガス流動を促進することができて、追
加燃料の燃焼性を向上させることができる。In this embodiment (1), during the additional fuel injection control, the exhaust SCV 21 is controlled to be closed and the exhaust valve opening timing is controlled to be advanced. Only one of them may be performed. Even in this case, the gas flow in the cylinder can be promoted, and the combustibility of the additional fuel can be improved.
【0056】また、本実施形態(1)では、主噴射量、
筒内ガス中の残存酸素量、イオン残存時期によって、追
加燃料の完全燃焼可能な噴射量や適正な噴射時期が変化
することを考慮し、追加燃料の噴射量と噴射時期を、主
噴射量、筒内ガス中の残存酸素量、イオン残存時期に基
づいて制御するようにしたので、追加燃料の噴射を適正
な時期に適正な噴射量で行うことが可能となり、燃費悪
化や排気エミッション悪化を防止しつつ、リーンNOx
触媒33を早期に活性化させることができる。In this embodiment (1), the main injection amount,
Considering that the amount of additional fuel that can be completely combusted and the appropriate injection timing will change depending on the amount of residual oxygen in the cylinder gas and the ion remaining timing, the injection amount and injection timing of the additional fuel are determined by the main injection amount, Control is performed based on the amount of oxygen remaining in the cylinder gas and the timing of remaining ions, so that additional fuel can be injected at the right time with the right amount of injection, preventing fuel consumption deterioration and exhaust emission deterioration. While lean NOx
The catalyst 33 can be activated at an early stage.
【0057】尚、主噴射量は、エンジン回転数、エンジ
ン負荷等のエンジン運転状態に応じて設定されるため、
追加燃料の噴射量と噴射時期を算出する際に主噴射量を
反映させれば、エンジン回転数、エンジン負荷等のエン
ジン運転状態も間接的に反映させることができる。その
他、冷却水温(エンジン温度)や排気温度も、追加燃料
の燃焼性に影響を及ぼすため、これらを追加燃料の噴射
量と噴射時期に反映させるようにしても良い。但し、本
発明は、追加燃料の噴射量と噴射時期のいずれか一方又
は両方を固定値としても良い。Incidentally, the main injection amount is set according to the engine operating state such as the engine speed and the engine load.
If the main injection amount is reflected when calculating the injection amount and the injection timing of the additional fuel, the engine operation state such as the engine speed and the engine load can also be reflected indirectly. In addition, since the cooling water temperature (engine temperature) and the exhaust temperature also affect the combustibility of the additional fuel, these may be reflected in the injection amount and the injection timing of the additional fuel. However, in the present invention, one or both of the injection amount and the injection timing of the additional fuel may be set to a fixed value.
【0058】また、本実施形態(1)では、追加燃料噴
射を行う時以外は、排気SCV21を全開状態に保持す
るようにしたが、エンジン運転中に排気SCV21の開
度を制御することで、筒内排気残留量(内部EGR量)
を制御するようにしても良い(この機能が特許請求の範
囲でいう排気残留量制御手段に相当する)。このように
すれば、排気SCV21の開度を制御することで、内部
EGR(内部排気ガス再循環)を実現でき、この内部E
GRとリーンNOx触媒33との組み合わせで排気浄化
性能を向上できると共に、外部のEGR装置を廃止する
ことが可能となり、コスト低減にもつながる。In the present embodiment (1), the exhaust SCV 21 is held in the fully open state except when additional fuel injection is performed. However, by controlling the opening of the exhaust SCV 21 during operation of the engine, In-cylinder exhaust residual amount (internal EGR amount)
May be controlled (this function corresponds to the residual exhaust gas amount control means in the claims). In this way, by controlling the opening of the exhaust SCV 21, internal EGR (internal exhaust gas recirculation) can be realized.
Exhaust gas purification performance can be improved by combining the GR and the lean NOx catalyst 33, and an external EGR device can be eliminated, leading to cost reduction.
【0059】[実施形態(2)]ところで、リーンNO
x触媒33は、排気ガス中の酸素濃度が高いリーン運転
中に、排気ガス中のNOxを吸蔵し、空燃比がリッチ又
は理論空燃比に切り換えられて排気ガス中の酸素濃度が
低下した時に、それまでに吸蔵したNOxを還元浄化す
る。従って、リーンNOx触媒33のNOx浄化性能を
維持するためには、リーン運転中に、時々、リッチ運転
(又はストイキ運転)に切り換える必要がある。しか
し、リーン運転からリッチ運転に切り換える際に、主燃
料の噴射量を増量すると、トルクショックが発生し、ド
ライバビリティが低下する欠点がある。[Embodiment (2)] By the way, lean NO
The x catalyst 33 stores NOx in the exhaust gas during the lean operation in which the oxygen concentration in the exhaust gas is high, and when the air-fuel ratio is switched to the rich or stoichiometric air-fuel ratio and the oxygen concentration in the exhaust gas decreases, The NOx stored so far is reduced and purified. Therefore, in order to maintain the NOx purification performance of the lean NOx catalyst 33, it is necessary to occasionally switch to the rich operation (or the stoichiometric operation) during the lean operation. However, when switching from the lean operation to the rich operation, if the injection amount of the main fuel is increased, a torque shock occurs and drivability is disadvantageously reduced.
【0060】そこで、図6に示す本発明の実施形態
(2)では、リーン運転時間が一定時間に達する毎に、
一時的に、点火後の膨張行程又は排気行程で1回又は複
数回の追加燃料を噴射して該追加燃料を点火による主燃
焼の火炎で後燃焼させることで排気ガスの空燃比をリッ
チ又は理論空燃比に切り換えて、リーンNOx触媒33
に吸蔵されているNOxを還元浄化する。Therefore, in the embodiment (2) of the present invention shown in FIG. 6, every time the lean operation time reaches a certain time,
The air-fuel ratio of the exhaust gas is increased or reduced by temporarily injecting additional fuel one or more times in an expansion stroke or an exhaust stroke after ignition and post-burning the additional fuel with a main combustion flame by ignition. Switching to the air-fuel ratio, the lean NOx catalyst 33
To reduce and purify the NOx stored in the tank.
【0061】以下、このNOx還元浄化制御を実行する
図6のプログラムの処理内容を説明する。本プログラム
は、所定時間毎に繰り返し実行される。本プログラムが
起動されると、まずステップ101で、NOx還元浄化
制御フラグFnoxが“NOx還元浄化制御実施中”を
意味する“1”であるか否かを判定し、Fnox=
“0”の場合、つまりNOx還元浄化制御を行っていな
い場合には、ステップ302に進み、リーン運転時間が
一定時間に達したか否かを判定し、一定時間に達してい
なければ、リーンNOx触媒33のNOx還元浄化は不
要と判断し、以降の処理を行うことなく、本プログラム
を終了する。Hereinafter, the processing contents of the program of FIG. 6 for executing the NOx reduction purification control will be described. This program is repeatedly executed at predetermined time intervals. When the present program is started, first, in step 101, it is determined whether or not the NOx reduction / purification control flag Fnox is “1” meaning “under execution of the NOx reduction / purification control”.
If “0”, that is, if the NOx reduction purification control is not being performed, the process proceeds to step 302, where it is determined whether the lean operation time has reached a certain time or not. It is determined that the NOx reduction purification of the catalyst 33 is unnecessary, and this program is ended without performing the subsequent processing.
【0062】その後、リーン運転時間が一定時間に達し
た時点で、リーンNOx触媒33のNOx還元浄化が必
要と判断して、ステップ303に進み、NOx還元浄化
制御フラグFnoxを“NOx還元浄化制御実施中”を
意味する“1”にセットし、点火後の膨張行程又は排気
行程で1回又は複数回の追加燃料を噴射して該追加燃料
を点火による主燃焼の火炎で後燃焼させることで排気ガ
スの空燃比をリッチ又は理論空燃比に切り換えて、リー
ンNOx触媒33に吸蔵されているNOxを還元浄化す
る。Thereafter, when the lean operation time reaches a predetermined time, it is determined that the NOx reduction purification of the lean NOx catalyst 33 is necessary, and the routine proceeds to step 303, where the NOx reduction purification control flag Fnox is set to "NOx reduction purification control execution". It is set to "1" which means "medium", and one or more times of additional fuel is injected in the expansion stroke or the exhaust stroke after ignition, and the additional fuel is post-combusted with the main combustion flame by ignition to exhaust. The air-fuel ratio of the gas is switched to the rich or stoichiometric air-fuel ratio to reduce and purify the NOx stored in the lean NOx catalyst 33.
【0063】NOx還元浄化制御の実行中は、ステップ
301で「Yes」と判定されてステップ304に進
み、NOx還元浄化制御の実行時間が所定時間に達した
か否かを判定し、所定時間に達していなければ、本プロ
グラムを終了するという処理を繰り返す。そして、NO
x還元浄化制御の実行時間が所定時間に達した時点で、
ステップ304からステップ305に進み、NOx還元
浄化制御フラグFnoxを“NOx還元浄化制御実施せ
ず”を意味する“0”にセットしてNOx還元浄化制御
を終了する。これにより、リーン運転時間が一定時間に
達する毎に、追加燃料噴射によるNOx還元浄化制御が
所定時間だけ実施される。During execution of the NOx reduction / purification control, "Yes" is determined in step 301, and the routine proceeds to step 304, where it is determined whether or not the execution time of the NOx reduction / purification control has reached a predetermined time. If not, the process of ending this program is repeated. And NO
When the execution time of the x reduction purification control reaches a predetermined time,
The process proceeds from step 304 to step 305, where the NOx reduction / purification control flag Fnox is set to "0" meaning "no NOx reduction / purification control is performed", and the NOx reduction / purification control is terminated. Thus, every time the lean operation time reaches a certain time, the NOx reduction / purification control by the additional fuel injection is performed for a predetermined time.
【0064】追加燃料噴射の実行中は、前記実施形態
(1)と同じく、排気SCV21を閉じ側に制御して、
排気行程中に気筒内のガス流動にスワールを発生させた
り、及び/又は、排気弁の開弁タイミングを進角側に制
御して、気筒内の燃焼ガスの一部を片方の排気ポート1
9bに向けて流動させて、気筒内のガス流動を促進し、
追加燃料の燃焼性を向上させるようにしても良い。During the execution of the additional fuel injection, the exhaust SCV 21 is controlled to the closed side as in the first embodiment (1).
A swirl is generated in the gas flow in the cylinder during the exhaust stroke, and / or the opening timing of the exhaust valve is controlled to the advanced side, so that a part of the combustion gas in the cylinder is discharged to one exhaust port 1.
9b to promote gas flow in the cylinder,
The combustibility of the additional fuel may be improved.
【0065】以上説明した本実施形態(2)では、点火
後に噴射した追加燃料は、燃焼してもエンジン出力があ
まり変化しないという点に着目し、リーンNOx触媒3
3に吸蔵されているNOxを還元浄化する際に、追加燃
料の噴射によってリッチ運転に切り換えるようにしたの
で、トルクショックを伴わずにリーン運転からリッチ運
転に切り換えることができ、ドライバビリティを向上す
ることができる。In the embodiment (2) described above, attention is paid to the point that the engine output of the additional fuel injected after the ignition does not change much even if it is burned.
When the NOx stored in the fuel cell 3 is reduced and purified, the operation is switched to the rich operation by the injection of the additional fuel, so that the operation can be switched from the lean operation to the rich operation without a torque shock, and the drivability is improved. be able to.
【0066】尚、本実施形態(2)では、リーン運転時
間が一定時間に達する毎に、追加燃料噴射によるNOx
還元浄化制御を実行するようにしたが、例えば、リーン
NOx触媒33の下流側にNOx濃度センサを設置し
て、リーンNOx触媒33から流出する排気ガス中のN
Ox濃度をNOx濃度センサで検出し、リーンNOx触
媒33から流出する排気ガス中のNOx濃度が増加して
判定値を越えたときに、追加燃料噴射によるNOx還元
浄化制御を所定時間だけ実行するようにしても良い。In this embodiment (2), every time the lean operation time reaches a certain time, NOx by additional fuel injection
The reduction purification control is executed. For example, a NOx concentration sensor is installed downstream of the lean NOx catalyst 33, and N2 in the exhaust gas flowing out of the lean NOx catalyst 33 is reduced.
The Ox concentration is detected by the NOx concentration sensor, and when the NOx concentration in the exhaust gas flowing out from the lean NOx catalyst 33 increases and exceeds the determination value, the NOx reduction / purification control by additional fuel injection is executed for a predetermined time. You may do it.
【0067】[実施形態(3)]一般に、筒内噴射エン
ジンは、低燃費、高出力の特長をもつが、更なる高出力
化、省燃費化を狙って、筒内噴射エンジンに、排気圧力
によって駆動される過給機(ターボチャージャ)を装着
することが検討されている。しかし、過給機を装着する
と、過給機自体の応答性の悪さによって、筒内噴射エン
ジンの特長である加速レスポンスの良さが損なわれてし
まう。[Embodiment (3)] In general, an in-cylinder injection engine has features of low fuel consumption and high output, but in order to further increase output and save fuel, the in-cylinder injection engine is provided with an exhaust pressure. Attachment of a supercharger (turbocharger) driven by is considered. However, when the supercharger is mounted, the poor response of the supercharger itself impairs the good acceleration response characteristic of the direct injection engine.
【0068】そこで、本発明の実施形態(3)では、筒
内噴射エンジンに、排気圧力によって駆動される過給機
を装着し、図7のプログラムを所定時間毎又は所定クラ
ンク角毎に実行することで、筒内噴射エンジンの特長で
ある加速レスポンスの良さを確保する。本プログラムで
は、まずステップ401で、加速時か否かを、例えばア
クセル開度の変化量から判定し、加速時でなければ、追
加燃料噴射による排気圧力上昇制御を行わないが、加速
時であれば、ステップ402に進み、追加燃料噴射によ
る排気圧力上昇制御を行う。この排気圧力上昇制御中
は、点火後の膨張行程又は排気行程で1回又は複数回の
追加燃料を噴射して該追加燃料を点火による主燃焼の火
炎で後燃焼させることで、排気圧力を上昇させて過給機
の応答性を向上させる。Therefore, in the embodiment (3) of the present invention, a supercharger driven by exhaust pressure is mounted on the in-cylinder injection engine, and the program shown in FIG. 7 is executed every predetermined time or every predetermined crank angle. This ensures good acceleration response, a feature of the direct injection engine. In this program, first, in step 401, it is determined whether or not the vehicle is accelerating, for example, based on the amount of change in the accelerator opening. Unless the vehicle is accelerating, the exhaust pressure increase control by additional fuel injection is not performed. For example, the routine proceeds to step 402, where exhaust pressure increase control is performed by additional fuel injection. During this exhaust pressure increase control, the exhaust pressure is increased by injecting additional fuel one or more times in the expansion stroke or the exhaust stroke after ignition and post-combustion of the additional fuel by the flame of the main combustion by ignition. This improves the responsiveness of the turbocharger.
【0069】追加燃料噴射の実行中は、前記実施形態
(1)と同じく、排気SCV21を閉じ側に制御して、
排気行程中に気筒内のガス流動にスワールを発生させた
り、及び/又は、排気弁の開弁タイミングを進角側に制
御して、気筒内の燃焼ガスの一部を片方の排気ポート1
9bに向けて流動させて、気筒内のガス流動を促進し、
追加燃料の燃焼性を向上させるようにしても良い。During the execution of the additional fuel injection, the exhaust SCV 21 is controlled to the closed side as in the first embodiment (1).
A swirl is generated in the gas flow in the cylinder during the exhaust stroke, and / or the opening timing of the exhaust valve is controlled to the advanced side, so that a part of the combustion gas in the cylinder is discharged to one exhaust port 1.
9b to promote gas flow in the cylinder,
The combustibility of the additional fuel may be improved.
【0070】以上説明した本実施形態(3)では、加速
時に、追加燃料噴射による排気圧力上昇制御を行うの
で、筒内噴射エンジンの大きな利点である加速レスポン
スの良さを損なわずに、過給機によって更なる高出力
化、省燃費化を実現することができる。In the above-described embodiment (3), during the acceleration, the exhaust pressure rise control is performed by the additional fuel injection, so that the supercharger can be used without deteriorating the acceleration response which is a great advantage of the in-cylinder injection engine. As a result, it is possible to further increase the output and reduce fuel consumption.
【0071】尚、上述した3つの実施形態(1)〜
(3)を組み合わせたり、2つの実施形態を組み合わせ
て実施しても良い。The above three embodiments (1) to (3)
(3) may be combined, or two embodiments may be combined.
【図1】本発明の実施形態(1)を示すエンジン制御シ
ステム全体の構成図FIG. 1 is a configuration diagram of an entire engine control system showing an embodiment (1) of the present invention.
【図2】アイドル制御プログラムの処理の流れを示すフ
ローチャート(その1)FIG. 2 is a flowchart showing a flow of processing of an idle control program (part 1);
【図3】アイドル制御プログラムの処理の流れを示すフ
ローチャート(その2)FIG. 3 is a flowchart showing a flow of processing of an idle control program (part 2);
【図4】追加燃料噴射量・噴射時期算出プログラムの処
理の流れを示すフローチャートFIG. 4 is a flowchart showing the flow of processing of an additional fuel injection amount / injection timing calculation program;
【図5】点火時期、主燃料噴射、追加燃料噴射のタイミ
ングを例示的に示すタイムチャートFIG. 5 is a time chart exemplarily showing ignition timing, main fuel injection, and timing of additional fuel injection;
【図6】本発明の実施形態(2)で用いるNOx還元浄
化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 NOx reduction purification control program used in the embodiment (2) of the present invention.
【図7】本発明の実施形態(3)で用いる排気圧力上昇
制御プログラムの処理の流れを示すフローチャートFIG. 7 is a flowchart showing a processing flow of an exhaust pressure rise control program used in the embodiment (3) of the present invention.
11…筒内噴射エンジン(筒内噴射式の内燃機関)、1
2…吸気管、18a,18b…吸気ポート、19a,1
9b…排気ポート、20…吸気スワールコントロールバ
ルブ(吸気SCV)、21…排気スワールコントロール
バルブ(排気SCV)、22…燃料噴射弁、23…点火
プラグ、26…水温センサ、27…排気弁開弁タイミン
グ変更装置、30…排気管、31…排気温度センサ、3
2…酸素センサ、33…リーンNOx触媒、34…触媒
温度センサ、36…ECU(追加燃料噴射制御手段,ガ
ス流動促進手段,燃焼方式切換手段,排気残留量制御手
段,燃焼状態判定手段)。11. In-cylinder injection engine (in-cylinder injection internal combustion engine), 1
2 ... intake pipe, 18a, 18b ... intake port, 19a, 1
9b ... exhaust port, 20 ... intake swirl control valve (intake SCV), 21 ... exhaust swirl control valve (exhaust SCV), 22 ... fuel injection valve, 23 ... spark plug, 26 ... water temperature sensor, 27 ... exhaust valve opening timing Change device, 30 ... exhaust pipe, 31 ... exhaust temperature sensor, 3
2. Oxygen sensor, 33: lean NOx catalyst, 34: catalyst temperature sensor, 36: ECU (additional fuel injection control means, gas flow promotion means, combustion mode switching means, exhaust residual amount control means, combustion state determination means).
───────────────────────────────────────────────────── 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) F01N 7/08 F01N 7/08 Z 3G301 F02B 37/00 302 F02B 37/00 302G F02D 9/04 F02D 9/04 A C 41/02 301 41/02 301F 41/34 41/34 E 43/00 301 43/00 301J 301T 45/00 368 45/00 368Z (72)発明者 斎藤 公孝 愛知県西尾市下羽角町岩谷14番地 株式会 社日本自動車部品総合研究所内 (72)発明者 森島 信悟 愛知県西尾市下羽角町岩谷14番地 株式会 社日本自動車部品総合研究所内 (72)発明者 二宮 正和 愛知県刈谷市昭和町1丁目1番地 株式会 社デンソー内 Fターム(参考) 3G004 AA01 BA06 DA03 DA24 DA25 3G005 DA01 EA04 EA16 FA04 GD02 HA05 HA09 JB01 JB02 3G065 AA03 AA04 AA06 AA07 AA10 CA12 CA13 CA14 DA04 DA15 EA02 EA03 GA05 GA08 GA09 GA10 GA17 GA41 HA02 HA21 HA22 KA02 KA12 3G084 AA04 BA13 BA15 BA24 CA02 CA03 CA04 DA02 DA10 DA11 EA11 EB11 EC02 EC03 FA18 FA19 FA20 FA27 FA29 FA33 FA38 FA39 3G091 AA02 AA10 AA11 AA12 AA17 AA24 AB06 BA03 BA32 CA13 CA18 CB02 CB03 CB05 CB07 CB08 DA10 DB06 DB07 DB10 DB13 DC01 EA00 EA01 EA05 EA07 EA16 EA17 EA18 EA27 EA28 EA31 EA33 EA34 FA02 FA04 FA17 FB02 FB10 FB11 FB12 FC07 HA36 HA37 HB02 HB03 HB05 HB06 3G301 HA04 HA16 HA19 JA02 JA04 JA24 KA05 KA07 KA12 LA00 LA01 LB04 MA11 MA19 MA26 NA08 NB02 ND01 NE11 NE13 NE14 NE15 NE19 PA01Z PA17Z PC00Z PD01Z PD03A PD11Z PD12Z PE01A PE01Z PE03Z PE04Z PE05Z PE08Z PE10Z ──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. 7 Identification symbol FI Theme coat ゛ (Reference) F01N 7/08 F01N 7/08 Z 3G301 F02B 37/00 302 F02B 37/00 302G F02D 9/04 F02D 9 / 04 AC 41/02 301 41/02 301F 41/34 41/34 E 43/00 301 43/00 301J 301T 45/00 368 45/00 368Z (72) Inventor: Kimitaka Saito 14 Iwatani, Shimowasukamachi, Nishio City, Aichi Prefecture. Address Japan Auto Parts Research Institute, Inc. (72) Inventor Shingo Morishima 14 Iwatani, Shimoba Kakucho, Nishio City, Aichi Prefecture Japan Auto Parts Research Institute, Inc. No. 1 F-term in Denso Corporation (reference) 3G004 AA01 BA06 DA03 DA24 DA25 3G005 DA01 EA04 EA16 FA04 GD02 HA05 HA09 JB01 JB02 3G065 AA03 AA04 AA06 AA07 AA10 CA12 CA13 CA14 DA04 DA15 EA02 EA03 GA05 GA08 GA09 GA10 GA17 GA41 HA02 HA21 HA22 KA02 KA12 3G084 AA04 BA13 BA15 BA24 CA02 CA03 CA04 DA02 DA10 DA11 FA23 FA19 FA23 AA02 AA10 AA11 AA12 AA17 AA24 AB06 BA03 BA32. HA16 HA19 JA02 JA04 JA24 KA05 KA07 KA12 LA00 LA01 LB04 MA11 MA19 MA26 NA08 NB02 ND01 NE11 NE13 NE14 NE15 NE19 PA01Z PA17Z PC00Z PD01Z PD03A PD11Z PD12Z PE01A PE01Z PE03Z PE04Z PE05Z PE08Z PE10Z
Claims (9)
に点火プラグで点火する筒内噴射式の内燃機関におい
て、 内燃機関の排気通路に設置された排気ガス浄化用の触媒
と、 前記触媒が活性化していない時に、点火後の膨張行程又
は排気行程で1回又は複数回の追加燃料を噴射して該追
加燃料を点火による主燃焼の火炎で後燃焼させることで
排気温度を上昇させて前記触媒を活性化させる追加燃料
噴射制御手段と、 前記追加燃料噴射制御手段による追加燃料噴射制御中に
気筒内のガス流動を促進して追加燃料の後燃焼を促進す
るガス流動促進手段とを備えていることを特徴とする内
燃機関制御装置。1. An in-cylinder injection type internal combustion engine in which fuel is directly injected into a cylinder and an air-fuel mixture is ignited by an ignition plug, wherein an exhaust gas purification catalyst installed in an exhaust passage of the internal combustion engine; When the catalyst is not activated, one or more times of additional fuel is injected during the expansion stroke or the exhaust stroke after ignition, and the additional fuel is post-combusted with the main combustion flame by ignition to raise the exhaust gas temperature. Additional fuel injection control means for activating the catalyst, and gas flow promotion means for promoting gas flow in the cylinder during additional fuel injection control by the additional fuel injection control means to promote post-combustion of additional fuel. An internal combustion engine control device, comprising:
られた複数の排気ポートのうちの1つの排気ポートに配
置された排気スワールコントロールバルブを備え、前記
追加燃料噴射制御手段による追加燃料噴射制御中に前記
排気スワールコントロールバルブを閉じ側に制御するこ
とを特徴とする請求項1に記載の内燃機関制御装置。2. The gas flow promoting means includes an exhaust swirl control valve disposed in one of a plurality of exhaust ports provided in each cylinder, and additional fuel injection by the additional fuel injection control means. The internal combustion engine control device according to claim 1, wherein the exhaust swirl control valve is controlled to be closed during the control.
噴射制御手段による追加燃料噴射制御中に排気弁の開弁
タイミングを進角側に制御することを特徴とする請求項
1に記載の内燃機関制御装置。3. The internal combustion engine according to claim 1, wherein the gas flow promoting unit controls the opening timing of the exhaust valve to the advanced side during the additional fuel injection control by the additional fuel injection control unit. Engine control device.
の噴射量と噴射時期のいずれか一方又は両方を、点火前
に噴射する主燃料の噴射量、機関回転数、機関負荷、機
関温度、排気温度、排気行程中の筒内燃焼状態、排気ガ
ス中の酸素濃度の少なくとも1つに基づいて制御するこ
とを特徴とする請求項1乃至3のいずれかに記載の内燃
機関制御装置。4. The additional fuel injection control means determines whether one or both of the additional fuel injection amount and the injection timing is the main fuel injection amount to be injected before ignition, the engine speed, the engine load, the engine temperature, 4. The internal combustion engine control device according to claim 1, wherein the control is performed based on at least one of an exhaust temperature, an in-cylinder combustion state during an exhaust stroke, and an oxygen concentration in the exhaust gas.
点火プラグを通して検出し、そのイオン電流に基づいて
排気行程中の筒内燃焼状態を判定する燃焼状態判定手段
を備え、 前記追加燃料噴射制御手段は、前記燃焼状態判定手段で
判定した排気行程中の筒内燃焼状態に基づいて追加燃料
の噴射量と噴射時期のいずれか一方又は両方を制御する
ことを特徴とする請求項4に記載の内燃機関制御装置。5. An additional fuel injection control means, comprising: combustion state determination means for detecting ions generated by combustion in a cylinder through the spark plug, and determining a combustion state in the cylinder during an exhaust stroke based on the ion current. 5. The internal combustion engine according to claim 4, wherein one or both of the injection amount and the injection timing of the additional fuel are controlled based on the in-cylinder combustion state during the exhaust stroke determined by the combustion state determination means. Engine control device.
度、排気温度、触媒温度の少なくとも1つに基づいて成
層燃焼と均質燃焼との間で切り換える燃焼方式切換手段
を備えていることを特徴とする請求項1乃至5のいずれ
かに記載の内燃機関制御装置。6. A combustion mode switching means for switching a combustion mode during idling between stratified combustion and homogeneous combustion based on at least one of an engine temperature, an exhaust gas temperature, and a catalyst temperature. An internal combustion engine control device according to any one of claims 1 to 5.
開度を制御することで筒内排気残留量を制御する排気残
留量制御手段を備えていることを特徴とする請求項2に
記載の内燃機関制御装置。7. An internal combustion engine control system according to claim 2, further comprising: an exhaust residual amount control means for controlling an in-cylinder residual exhaust amount by controlling an opening degree of said exhaust swirl control valve. .
に点火プラグで点火する筒内噴射式の内燃機関におい
て、 内燃機関の排気通路に設置されたリーンNOx触媒と、 前記リーンNOx触媒に吸蔵されているNOxを還元浄
化する際に、点火後の膨張行程又は排気行程で1回又は
複数回の追加燃料を噴射して該追加燃料を点火による主
燃焼の火炎で後燃焼させることで排気ガスの空燃比をリ
ッチ又は理論空燃比に切り換える追加燃料噴射制御手段
とを備えていることを特徴とする内燃機関制御装置。8. An in-cylinder injection type internal combustion engine in which fuel is directly injected into a cylinder and an air-fuel mixture is ignited by an ignition plug, wherein: a lean NOx catalyst installed in an exhaust passage of the internal combustion engine; When reducing and purifying NOx occluded in the combustion chamber, one or more additional fuels are injected in an expansion stroke or an exhaust stroke after ignition, and the additional fuel is post-combusted by a flame of main combustion by ignition. An internal combustion engine control device comprising: an additional fuel injection control unit that switches an air-fuel ratio of exhaust gas to a rich or stoichiometric air-fuel ratio.
に点火プラグで点火する筒内噴射式の内燃機関におい
て、 排気圧力によって駆動される過給機と、 加速時に、点火後の膨張行程又は排気行程で1回又は複
数回の追加燃料を噴射して該追加燃料を点火による主燃
焼の火炎で後燃焼させることで排気圧力を上昇させて前
記過給機の応答性を向上させる追加燃料噴射制御手段と
を備えていることを特徴とする内燃機関制御装置。9. A direct injection type internal combustion engine in which fuel is directly injected into a cylinder and an air-fuel mixture is ignited by an ignition plug, a supercharger driven by exhaust pressure, and a post-ignition expansion during acceleration. One or more additional fuels are injected in a stroke or an exhaust stroke, and the additional fuel is post-combusted by a flame of main combustion by ignition, thereby increasing exhaust pressure and improving responsiveness of the supercharger. An internal combustion engine control device comprising: a fuel injection control unit.
Priority Applications (1)
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JP11090506A JP2000282920A (en) | 1999-03-31 | 1999-03-31 | Control device of internal combustion engine |
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JP11090506A JP2000282920A (en) | 1999-03-31 | 1999-03-31 | Control device of internal combustion engine |
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WO2002035075A1 (en) * | 2000-10-26 | 2002-05-02 | Hitachi, Ltd. | Cylinder injection internal combustion engine |
JP2002303192A (en) * | 2001-03-30 | 2002-10-18 | Mazda Motor Corp | Fuel injection device of diesel engine and trouble diagnosing device for the device |
JP2002303179A (en) * | 2001-03-30 | 2002-10-18 | Mazda Motor Corp | Fuel injection device for diesel engine |
JP2002364413A (en) * | 2001-06-07 | 2002-12-18 | Mazda Motor Corp | Exhaust emission control device for cylinder injection type engine with turbo supercharger |
JP2003129852A (en) * | 2001-10-24 | 2003-05-08 | Hitachi Ltd | Engine supercharging system |
JP2013032710A (en) * | 2011-08-01 | 2013-02-14 | Toyota Motor Corp | Internal combustion engine control device |
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1999
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WO2002035075A1 (en) * | 2000-10-26 | 2002-05-02 | Hitachi, Ltd. | Cylinder injection internal combustion engine |
JP2002303192A (en) * | 2001-03-30 | 2002-10-18 | Mazda Motor Corp | Fuel injection device of diesel engine and trouble diagnosing device for the device |
JP2002303179A (en) * | 2001-03-30 | 2002-10-18 | Mazda Motor Corp | Fuel injection device for diesel engine |
JP4524530B2 (en) * | 2001-03-30 | 2010-08-18 | マツダ株式会社 | Fuel injection system for diesel engine |
JP4560979B2 (en) * | 2001-03-30 | 2010-10-13 | マツダ株式会社 | Fuel injection system for diesel engine |
JP2002364413A (en) * | 2001-06-07 | 2002-12-18 | Mazda Motor Corp | Exhaust emission control device for cylinder injection type engine with turbo supercharger |
JP2003129852A (en) * | 2001-10-24 | 2003-05-08 | Hitachi Ltd | Engine supercharging system |
JP2013032710A (en) * | 2011-08-01 | 2013-02-14 | Toyota Motor Corp | Internal combustion engine control device |
CN105715330A (en) * | 2014-12-18 | 2016-06-29 | 通用汽车环球科技运作有限责任公司 | Method of operating internal combustion engine |
JP2018003749A (en) * | 2016-07-05 | 2018-01-11 | トヨタ自動車株式会社 | Control device of internal combustion engine |
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