JPH1122508A - Fuel injection control device for internal combustion engine - Google Patents

Fuel injection control device for internal combustion engine

Info

Publication number
JPH1122508A
JPH1122508A JP9176239A JP17623997A JPH1122508A JP H1122508 A JPH1122508 A JP H1122508A JP 9176239 A JP9176239 A JP 9176239A JP 17623997 A JP17623997 A JP 17623997A JP H1122508 A JPH1122508 A JP H1122508A
Authority
JP
Japan
Prior art keywords
combustion
fuel
ratio
homogeneous
switching
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.)
Granted
Application number
JP9176239A
Other languages
Japanese (ja)
Other versions
JP3677947B2 (en
Inventor
Hatsuo Nagaishi
初雄 永石
Takamasa Ueda
隆正 上田
Hiroshi Iwano
岩野　　浩
Yuki Nakajima
祐樹 中島
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nissan Motor Co Ltd
Original Assignee
Nissan Motor Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Nissan Motor Co Ltd filed Critical Nissan Motor Co Ltd
Priority to JP17623997A priority Critical patent/JP3677947B2/en
Priority to KR1019980025490A priority patent/KR100317159B1/en
Priority to DE69838199T priority patent/DE69838199T2/en
Priority to EP98112067A priority patent/EP0889218B1/en
Priority to US09/108,409 priority patent/US6058905A/en
Publication of JPH1122508A publication Critical patent/JPH1122508A/en
Application granted granted Critical
Publication of JP3677947B2 publication Critical patent/JP3677947B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • 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
    • Y02T10/40—Engine management systems

Landscapes

  • Electrical Control Of Ignition Timing (AREA)
  • Combustion Methods Of Internal-Combustion Engines (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Abstract

PROBLEM TO BE SOLVED: To stabilize the combustibility when stratified combustion is switched to homogeneous combustion. SOLUTION: After stratified combustion is judged to be switched to homogeneous combustion, the equivalence ratio is gradually switched from the map retrieval value for the stratified combustion to the map retrieval value for the homogeneous combustion, and fuel is separately injected in a suction stroke and a compression stroke until the equivalence ratio being switched becomes the value subtracted with the prescribed deviation from the map retrieval value for the homogeneous combustion or below after it becomes the value added with the prescribed deviation to the map retrieval value for the stratified combustion or above.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、機関の運転条件に
応じて均質燃焼と成層燃焼とを切り換える内燃機関にお
いて、該燃料切換時の燃料噴射制御技術に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control technique at the time of fuel switching in an internal combustion engine that switches between homogeneous combustion and stratified combustion according to operating conditions of the engine.

【０００２】[0002]

【従来の技術】近年、直噴火花点火式内燃機関が注目さ
れており、このものでは、機関の運転条件に応じて、燃
焼方式を切換制御、すなわち、吸気行程にて燃料を噴射
することにより、燃焼室内に燃料を拡散させ均質の混合
気を形成して行う均質燃焼と、圧縮行程にて燃料を噴射
することにより、点火栓回りに集中的に層状の混合気を
形成して行う成層燃焼とに切換制御するのが一般的であ
る（特開昭５９−３７２３６号公報参照）。2. Description of the Related Art In recent years, a direct-injection spark ignition type internal combustion engine has attracted attention. In this engine, switching control of a combustion system is performed according to operating conditions of the engine, that is, by injecting fuel in an intake stroke. And homogeneous combustion in which fuel is diffused into the combustion chamber to form a homogeneous mixture, and stratified combustion in which fuel is injected in the compression stroke to form a layered mixture intensively around the spark plug. (See Japanese Patent Application Laid-Open No. S59-37236).

【０００３】上記燃焼切換を行なう機関において、機関
の回転速度と負荷（トルク) に基づいて燃焼領域を設定
したマップに、成層燃焼領域と均質燃焼領域に挟まれる
領域に、燃料を吸気行程と圧縮行程との２回に分けて噴
射する弱成層燃焼領域を設定するようにしたものがあ
る。すなわち、成層燃焼領域と均質燃焼領域とを切換時
にトルク段差がつかないように当量比を連続的に設定し
て隣接させると、両領域の境界付近では当量比がいずれ
の燃焼にも適合しなくなり、境界付近の成層燃焼領域で
は点火栓周りが過剰にリッチとなって失火やスモークの
増大を生じ、一方境界付近の均質燃焼領域では均質混合
気が過剰にリーンとなって失火が発生したり燃焼が不安
定となったりする。[0003] In an engine that performs the above-mentioned combustion switching, a map in which a combustion region is set based on the rotational speed and load (torque) of the engine is used. There is one in which a weak stratified combustion region in which the injection is performed in two stages of the stroke is set. In other words, when the stratified combustion region and the homogeneous combustion region are switched and the equivalence ratio is continuously set so that a torque step does not occur at the time of switching, the equivalence ratio becomes incompatible with any combustion near the boundary between both regions. However, in the stratified combustion region near the boundary, the area around the spark plug becomes excessively rich, causing misfires and increased smoke, while in the homogeneous combustion region near the boundary, the homogeneous mixture becomes excessively lean, causing misfires and combustion. May become unstable.

【０００４】そこで、成層燃焼領域と均質燃焼領域との
間に設定した領域で、点火時期の設定等により基本的に
は成層燃焼を行い、燃料噴射を吸気行程と圧縮行程との
２回に分けて噴射する構成としており、これにより、点
火栓周りの混合比が過剰にリッチとなることを抑制しつ
つ成層燃焼を行って失火やスモークの増大を抑制すると
同時に、均質燃焼による失火や燃焼不安定の発生も抑制
できる。Therefore, in a region set between the stratified combustion region and the homogeneous combustion region, stratified charge combustion is basically performed by setting ignition timing or the like, and fuel injection is divided into two stages, an intake stroke and a compression stroke. With this configuration, stratified combustion is performed while suppressing the mixture ratio around the spark plug from becoming excessively rich to suppress misfires and increase in smoke, and at the same time misfires and unstable combustion due to homogeneous combustion are performed. Can also be suppressed.

【０００５】本発明は、このような従来の課題に着目し
てなされたもので、燃焼切換時の当量比制御と分割噴射
とを適切に併用することにより、上記問題点を解消した
内燃機関の燃料噴射制御装置を提供することを目的とす
る。The present invention has been made in view of such a conventional problem, and an internal combustion engine which solves the above-mentioned problems by appropriately using the equivalence ratio control at the time of combustion switching and split injection. It is an object to provide a fuel injection control device.

【０００６】[0006]

【発明が解決しようとする課題】しかしながら、上記従
来の燃料噴射分割方式では、前記特定した弱成層燃焼領
域において定常状態でも２回に分けて噴射する方式であ
るため、以下のような問題を生じていた。噴射を２回に
分けると１回当たりの噴射量が減少するため、燃料噴射
弁のオフセット誤差（パルス幅−燃料量特性のドリフト
分) が大きくなり、１回噴射方式に比較して空燃比制御
精度が低下し、排気エミッション特性，運転性が悪化す
る。However, in the above-described conventional fuel injection splitting method, the fuel is divided into two injections even in the steady state in the specified weak stratified combustion region, so that the following problem arises. I was If the injection is divided into two injections, the injection amount per injection decreases, so the offset error (pulse width-fuel amount characteristic drift) of the fuel injection valve increases, and the air-fuel ratio control is compared with the single injection method. Accuracy decreases and exhaust emission characteristics and operability deteriorate.

【０００７】吸気行程で噴射される燃料量が少ないため
均質混合気が過剰にリーンで成層燃焼での燃焼火炎が消
炎してしまい、ＨＣ（未燃燃料) の排出量が増加する。
特に低負荷域で分割噴射すると２回目の噴射で可燃混合
気を形成するため、１回目は多く噴けないので均質部分
が超希薄となり、この傾向が増大する。定常運転時も分
割噴射を行うため、高電圧昇圧方式の燃料噴射弁を駆動
するドライブユニットの発熱量が増大し、発熱容量を満
たすように２系統とするとユニットが高価についてしま
う。[0007] Since the amount of fuel injected in the intake stroke is small, the homogeneous mixture is excessively lean and the combustion flame in stratified combustion extinguishes, thereby increasing the amount of HC (unburned fuel) emission.
In particular, when the divided injection is performed in the low load region, a combustible air-fuel mixture is formed in the second injection, so that the first injection is not performed much, so that the homogeneous portion becomes ultra-lean, and this tendency is increased. Since split injection is performed even during steady operation, the amount of heat generated by the drive unit that drives the high-voltage booster fuel injection valve increases. If two systems are used to satisfy the heat generation capacity, the unit becomes expensive.

【０００８】[0008]

【課題を解決するための手段】このため、請求項１に係
る発明は、シリンダ内に燃料を噴射供給する直接噴射式
内燃機関において、機関の運転状態に基づいて、吸気行
程で比較的リッチな当量比となるように燃料を供給する
均質燃焼条件と、圧縮行程で比較的リーンな当量比とな
るように燃料を供給する成層燃焼条件とを判別し、前記
均質燃焼条件と成層燃焼条件との判別が切り換わったと
きに、前記リッチな当量比とリーンな当量比との間で当
量比を徐々に切り換えると共に、該切換期間中の少なく
とも所定期間、吸気行程と圧縮行程との両方に分けて燃
料を供給するようにしたことを特徴とする。SUMMARY OF THE INVENTION Accordingly, the invention according to claim 1 is directed to a direct injection type internal combustion engine that injects fuel into a cylinder, based on the operating state of the engine, in which the intake stroke is relatively rich. A homogeneous combustion condition for supplying fuel so as to have an equivalent ratio, and a stratified combustion condition for supplying fuel so as to have a relatively lean equivalent ratio in a compression stroke are determined, and the homogeneous combustion condition and the stratified combustion condition are determined. When the determination is switched, the equivalent ratio is gradually switched between the rich equivalent ratio and the lean equivalent ratio, and at least a predetermined period of the switching period is divided into both the intake stroke and the compression stroke. It is characterized in that fuel is supplied.

【０００９】また、請求項２に係る発明は図１に示すよ
うに、シリンダ内に燃料を噴射供給する直接噴射式内燃
機関において、機関の運転状態を検出する運転状態検出
手段と、検出された運転状態に基づいて、吸気行程で比
較的リッチな当量比となるように燃料を供給する均質燃
焼条件と、圧縮行程で比較的リーンな当量比となるよう
に燃料を供給する成層燃焼条件とを判別する燃焼条件判
別手段と、前記均質燃焼条件と成層燃焼条件との判別が
切り換わったときに、前記リッチな当量比とリーンな当
量比との間で当量比を徐々に切り換える当量比切換手段
と、前記当量比切換手段による当量比の切換期間中の少
なくとも所定期間、吸気行程と圧縮行程との両方に分け
て燃料を供給する燃料分割供給手段と、を含んで構成し
たことを特徴とする。According to a second aspect of the present invention, as shown in FIG. 1, in a direct injection type internal combustion engine for injecting fuel into a cylinder, operating state detecting means for detecting an operating state of the engine is provided. Based on the operating state, a homogeneous combustion condition for supplying fuel so as to have a relatively rich equivalent ratio in the intake stroke, and a stratified combustion condition for supplying fuel so as to have a relatively lean equivalent ratio in the compression stroke. Combustion condition determining means for determining, and equivalent ratio switching means for gradually switching the equivalent ratio between the rich equivalent ratio and the lean equivalent ratio when the determination between the homogeneous combustion condition and the stratified combustion condition is switched. And fuel split supply means for supplying fuel separately for both the intake stroke and the compression stroke for at least a predetermined period during the equivalence ratio switching period by the equivalence ratio switching means. .

【００１０】これらの発明において、機関の運転状態、
例えば回転速度と負荷とに基づいて均質燃焼条件と成層
燃焼条件とを判別し、該判別が切り換わったときは、当
量比を均質燃焼条件における比較的リッチな当量比と成
層燃焼条件における比較的リーンな当量比との間で、徐
々に時間を掛けて切り換える。このように均質燃焼と成
層燃焼との切換時に、時間を掛けた当量比の切換によっ
てトルク段差の発生を回避できるため、均質燃焼領域と
成層燃焼領域とを当量比に差をつけて隣接させることが
でき、この結果、均質燃焼領域と成層燃焼領域との境界
付近においても、それぞれ安定した燃焼が得られ、空燃
比精度を高く維持でき、失火の発生やスモークの増大を
抑制できる。In these inventions, the operating state of the engine,
For example, the homogeneous combustion condition and the stratified combustion condition are determined based on the rotation speed and the load, and when the determination is switched, the equivalent ratio is set to a relatively rich equivalent ratio in the homogeneous combustion condition and a relatively rich equivalent ratio in the stratified combustion condition. Switch over slowly between lean equivalent ratios over time. As described above, when switching between the homogeneous combustion and the stratified combustion, it is possible to avoid the occurrence of a torque step by switching the equivalent ratio over time, so that the homogeneous combustion region and the stratified combustion region are adjacent to each other with a difference in the equivalent ratio. As a result, stable combustion can be obtained even in the vicinity of the boundary between the homogeneous combustion region and the stratified combustion region, and the air-fuel ratio accuracy can be kept high, and the occurrence of misfire and the increase in smoke can be suppressed.

【００１１】そして、該当量比を切り換える過渡時に吸
気行程と圧縮行程とに分割して燃料を噴射する構成とし
て、点火栓周辺の混合比を適度にリッチ状態に維持しつ
つ、その外側に均質な混合気を形成して燃焼させること
により、空燃比の燃焼限界が拡がり、失火を防止しつつ
安定した燃焼を得ることができる。また、前記分割噴射
時に吸気行程での噴射により形成された燃料均質混合気
が希薄になり過ぎることがあるとしても、切換時に一時
的に発生するだけであり、従来のように定常的な分割噴
射によるＨＣの増大も抑制できる。The fuel injection is divided into an intake stroke and a compression stroke during a transition when the corresponding ratio is switched, so that the mixture ratio around the spark plug is maintained at a moderately rich state while a homogeneous mixture is provided on the outside thereof. By forming the air-fuel mixture and burning, the combustion limit of the air-fuel ratio is widened, and stable combustion can be obtained while preventing misfire. Further, even if the fuel-homogeneous mixture formed by the injection in the intake stroke at the time of the split injection may become too lean, it is only temporarily generated at the time of switching, and the conventional split injection as in the prior art. Can also suppress the increase in HC.

【００１２】また、分割噴射が一時的に行うものである
ため、ドライブユニットの発熱量の増大も抑制でき、定
常的に分割噴射する場合のように昇圧系統を２系統設け
る必要もなく、安価なユニットを使用できる。また、請
求項３に係る発明は、成層燃焼から均質燃焼への切換時
において前記燃料を両行程に分けて供給する条件は、前
記燃焼の切換要求が発生してから、該均質燃焼に対応し
た点火時期の切換が行なわれるまでの間であることを特
徴とする。In addition, since the split injection is performed temporarily, it is possible to suppress an increase in the amount of heat generated by the drive unit. Can be used. Further, in the invention according to claim 3, when switching from stratified combustion to homogeneous combustion, the condition that the fuel is supplied in two strokes corresponds to the homogeneous combustion after the combustion switching request is generated. It is characterized by a period until the ignition timing is switched.

【００１３】分割噴射の場合、基本的な燃焼は成層燃焼
であるため、点火時期も成層燃料に合わせて設定され、
均質燃焼に応じた点火時期の切換により実際の均質燃焼
へ切り換えるまでの切換期間中に分割噴射が実行され
る。また、請求項４に係る発明は、前記燃料を両行程に
分けて供給する条件は、所定の当量比範囲とすることを
特徴とする。In the case of split injection, since the basic combustion is stratified combustion, the ignition timing is set according to the stratified fuel.
The split injection is executed during the switching period until switching to the actual homogeneous combustion by switching the ignition timing according to the homogeneous combustion. Further, the invention according to claim 4 is characterized in that the condition for supplying the fuel in both strokes is a predetermined equivalence ratio range.

【００１４】分割噴射の実行条件を当量比の範囲で規定
することにより、確実に可燃混合気を形成することがで
き、リッチ過剰やリーン過剰による失火を防止でき、安
定燃焼を確保できる。また、請求項５に係る発明は、前
記燃料を両行程に分けて供給する条件は、前記徐々に切
り換えられる当量比が、切換前の燃焼条件における当量
比に対し所定値以上の偏差を有してから、切換後の燃焼
条件における当量比に対し所定値以下の偏差となるまで
とすることを特徴とする。By defining the execution conditions of the split injection within the range of the equivalence ratio, a combustible air-fuel mixture can be reliably formed, misfire due to excessive rich or excessive lean can be prevented, and stable combustion can be ensured. Further, in the invention according to claim 5, the condition in which the fuel is supplied in two strokes is such that the gradually switched equivalent ratio has a deviation of a predetermined value or more with respect to the equivalent ratio in the combustion condition before switching. After that, until the deviation becomes equal to or less than a predetermined value with respect to the equivalent ratio under the changed combustion condition.

【００１５】前記同様に分割噴射の実行条件を当量比の
範囲で規定し、かつ、切換前後の燃焼条件における当量
比に対して偏差を持たせて規定したことにより、より適
切な範囲で分割噴射を実行することができる。また、請
求項６に係る発明は、均質燃焼条件が理論空燃比での燃
焼である場合、該理論空燃比相当の当量比に対し、前記
所定値は機関回転速度に基づいて設定されることを特徴
とする。In the same manner as described above, the execution conditions of the divided injection are defined in the range of the equivalence ratio, and the equivalence ratio in the combustion conditions before and after the switching is defined with a deviation, so that the divided injection can be performed in a more appropriate range. Can be performed. In the invention according to claim 6, when the homogeneous combustion condition is combustion at a stoichiometric air-fuel ratio, the predetermined value is set based on an engine speed with respect to an equivalence ratio corresponding to the stoichiometric air-fuel ratio. Features.

【００１６】均質燃焼のリーン限界当量比は、機関回転
速度によって定まるため、機関回転速度によって分割噴
射を実行する当量比を規定する偏差を設定することで、
さらに適切な範囲で分割噴射を実行することができる。Since the lean limit equivalent ratio of the homogeneous combustion is determined by the engine speed, by setting a deviation that defines the equivalent ratio for executing the split injection by the engine speed,
Further, the split injection can be performed in an appropriate range.

【００１７】[0017]

【発明の実施の形態】以下に本発明の実施の形態を説明
する。図２は実施の一形態を示す直噴火花点火式内燃機
関のシステム図である。車両に搭載される内燃機関１の
各気筒の燃焼室には、エアクリーナ２から吸気通路３に
より、電制スロットル弁４の制御を受けて、空気が吸入
される。Embodiments of the present invention will be described below. FIG. 2 is a system diagram of a direct injection spark ignition type internal combustion engine showing an embodiment. Air is sucked into the combustion chamber of each cylinder of the internal combustion engine 1 mounted on the vehicle from the air cleaner 2 through the intake passage 3 under the control of the electronically controlled throttle valve 4.

【００１８】電制スロットル弁４は、コントロールユニ
ット２０からの信号により作動するステップモータ等に
より開度制御される。そして、燃焼室内に燃料（ガソリ
ン）を直接噴射するように、電磁式の燃料噴射弁（イン
ジェクタ）５が設けられている。燃料噴射弁５は、コン
トロールユニット２０から機関回転に同期して吸気行程
又は圧縮行程にて出力される噴射パルス信号によりソレ
ノイドに通電されて開弁し、所定圧力に調圧された燃料
を噴射するようになっている。そして、噴射された燃料
は、吸気行程噴射の場合は燃焼室内に拡散して均質な混
合気を形成し、また圧縮行程噴射の場合は点火栓６回り
に集中的に層状の混合気を形成し、コントロールユニッ
ト２０からの点火信号に基づき、点火栓６により点火さ
れて、燃焼（均質燃焼又は成層燃焼）する。尚、燃焼方
式は、当量比制御との組合わせで、均質ストイキ燃焼、
均質リーン燃焼（空燃比２０〜３０）、成層リーン燃焼
（当量比４０程度）に分けられる。The opening of the electronically controlled throttle valve 4 is controlled by a step motor or the like operated by a signal from the control unit 20. An electromagnetic fuel injection valve (injector) 5 is provided so as to directly inject fuel (gasoline) into the combustion chamber. The fuel injection valve 5 is energized by a solenoid in response to an injection pulse signal output in an intake stroke or a compression stroke from the control unit 20 in synchronization with engine rotation, opens the valve, and injects fuel adjusted to a predetermined pressure. It has become. The injected fuel diffuses into the combustion chamber in the case of the intake stroke injection to form a homogeneous mixture, and in the case of the compression stroke injection, forms a stratified mixture around the ignition plug 6. Based on an ignition signal from the control unit 20, the ignition plug 6 ignites the fuel and performs combustion (homogeneous combustion or stratified combustion). The combustion method is a combination of equivalent ratio control, homogeneous stoichiometric combustion,
It is divided into homogeneous lean combustion (air-fuel ratio of 20 to 30) and stratified lean combustion (equivalent ratio of about 40).

【００１９】機関１からの排気は排気通路７より排出さ
れ、排気通路７には排気浄化用の触媒８が介装されてい
る。コントロールユニット２０は、ＣＰＵ、ＲＯＭ、Ｒ
ＡＭ、Ａ／Ｄ変換器及び入出力インターフェイス等を含
んで構成されるマイクロコンピュータを備え、各種のセ
ンサから信号が入力されている。Exhaust gas from the engine 1 is exhausted from an exhaust passage 7, and an exhaust purification catalyst 8 is interposed in the exhaust passage 7. The control unit 20 includes a CPU, a ROM, an R
A microcomputer including an AM, an A / D converter, an input / output interface, and the like is provided, and signals are input from various sensors.

【００２０】前記各種のセンサとしては、エンジン１の
クランク軸又はカム軸回転を検出するクランク角センサ
２１，２２が設けられている。これらのクランク角セン
サ２１，２２は、気筒数をｎとすると、クランク角７２
０°／ｎ毎に、予め定めたクランク角位置（各気筒の圧
縮上死点前の所定クランク角位置）で基準パルス信号Ｒ
ＥＦを出力すると共に、１〜２°毎に単位パルス信号Ｐ
ＯＳを出力するもので、基準パルス信号ＲＥＦの周期な
どからエンジン回転数Ｎｅを算出可能である。As the various sensors, crank angle sensors 21 and 22 for detecting rotation of the crankshaft or camshaft of the engine 1 are provided. These crank angle sensors 21 and 22 have a crank angle of 72 when the number of cylinders is n.
At every 0 ° / n, the reference pulse signal R is set at a predetermined crank angle position (a predetermined crank angle position before the compression top dead center of each cylinder).
EF is output, and the unit pulse signal P
It outputs the OS, and the engine speed Ne can be calculated from the cycle of the reference pulse signal REF and the like.

【００２１】この他、吸気通路３のスロットル弁４上流
で吸入空気流量Ｑａを検出するエアフローメータ２３、
アクセル開度（アクセルペダルの踏込み量）ＡＣＣを検
出するアクセルセンサ２４、スロットル弁４の開度ＴＶ
Ｏを検出するスロットルセンサ２５（スロットル弁４の
全閉位置でＯＮとなるアイドルスイッチを含む）、エン
ジン１の冷却水温Ｔｗを検出する水温センサ２６、排気
通路７にて排気当量比のリッチ・リーンに応じた信号を
出力するＯ2 センサ２７、車速ＶＳＰを検出する車速セ
ンサ２８などが設けられている。In addition, an air flow meter 23 for detecting the intake air flow rate Qa upstream of the throttle valve 4 in the intake passage 3,
Accelerator sensor 24 for detecting accelerator opening (accelerator pedal depression amount) ACC, opening TV of throttle valve 4
A throttle sensor 25 for detecting O (including an idle switch that is turned on when the throttle valve 4 is fully closed), a water temperature sensor 26 for detecting a cooling water temperature Tw of the engine 1, a rich / lean exhaust ratio in the exhaust passage 7 An O 2 sensor 27 that outputs a signal corresponding to the vehicle speed, a vehicle speed sensor 28 that detects a vehicle speed VSP, and the like are provided.

【００２２】ここにおいて、コントロールユニット２０
は、前記各種のセンサからの信号を入力しつつ、内蔵の
マイクロコンピュータにより、所定の演算処理を行っ
て、電制スロットル弁４によるスロットル開度、燃料噴
射弁５による燃料噴射量、及び、点火栓６による点火時
期を制御する。次に、本発明の第１の実施形態に係る燃
焼切換時の制御機能を、図３のブロック図を参照して説
明する。Here, the control unit 20
Performs predetermined arithmetic processing by a built-in microcomputer while inputting signals from the above-mentioned various sensors, and performs throttle opening by the electronically controlled throttle valve 4, fuel injection amount by the fuel injection valve 5, and ignition. The ignition timing of the plug 6 is controlled. Next, a control function at the time of combustion switching according to the first embodiment of the present invention will be described with reference to the block diagram of FIG.

【００２３】均質当量比設定部Ａは、機関の回転速度，
負荷等の運転条件に基づいて均質燃焼時における当量比
を設定する。同様に成層当量比設定部Ｂは、機関の回転
速度，負荷等の運転条件に基づいて成層燃焼時における
当量比を設定する。均質／成層判定部Ｃは、機関の運転
条件に基づいて均質燃焼，成層燃焼のいずれを行なうべ
きかを判定する。The equivalent equivalence ratio setting section A is used to determine the rotational speed of the engine,
The equivalence ratio during homogeneous combustion is set based on operating conditions such as load. Similarly, the stratification equivalence ratio setting unit B sets the equivalence ratio during stratification combustion based on operating conditions such as the engine speed and load. The homogeneous / stratified determination unit C determines whether to perform homogeneous combustion or stratified combustion based on the operating conditions of the engine.

【００２４】切換部Ｄは、前記均質／成層判定部の判定
結果に基づいて、均質当量比設定部又は成層当量比設定
部のいずれかで設定された当量比に切り換えて設定す
る。遅延部Ｅは、切換部Ｄから出力された当量比を遅れ
処理する。これは、燃焼の切換に応じて当量比をステッ
プ的に切り換えると、吸入空気量の切換後の遅れにより
トルク段差を生じるため、当量比を空気量の遅れに合わ
せて徐々に変化させることにより、トルクを滑らかに変
化させるためである。The switching unit D switches and sets the equivalent ratio set by either the homogeneous equivalent ratio setting unit or the stratified equivalent ratio setting unit based on the determination result of the homogeneous / stratified determination unit. The delay unit E delays the equivalent ratio output from the switching unit D. This is because, when the equivalence ratio is switched stepwise in accordance with the switching of combustion, a torque step occurs due to a delay after switching of the intake air amount, so that the equivalence ratio is gradually changed in accordance with the delay of the air amount. This is for smoothly changing the torque.

【００２５】燃料噴射量算出部Ｆは、吸入空気量，機関
回転速度，前記遅れ処理された当量比を基本とし、水温
や当量比フィードバック補正係数等による各種補正を施
して燃料噴射量を算出する。配分率算出部Ｇは、切換部
Ｄ，遅延部Ｅのいずれかの当量比に基づいて、燃焼切換
時の吸気行程で噴射される均質燃焼用の燃料噴射量と、
圧縮行程で噴射される成層燃焼用の燃料噴射量との配分
率を算出する。The fuel injection amount calculation unit F calculates the fuel injection amount by performing various corrections based on the water temperature, the equivalent ratio feedback correction coefficient, and the like based on the intake air amount, the engine speed, and the equivalent ratio after the delay processing. . The distribution ratio calculating unit G calculates a fuel injection amount for homogeneous combustion injected in an intake stroke at the time of combustion switching based on an equivalent ratio of either the switching unit D or the delay unit E,
The distribution ratio with the fuel injection amount for stratified combustion injected in the compression stroke is calculated.

【００２６】吸気行程噴射量算出部Ｈ及び圧縮行程用噴
射量算出部Ｉは、前記燃料噴射量算出部Ｆで算出された
一行程当たりの総燃料噴射量を、配分率算出部Ｇで算出
された配分率に基づいて、吸気行程での燃料噴射量と圧
縮行程での燃料噴射量とに配分する。均質噴射時期算出
部Ｊ，成層噴射時期算出部Ｋは、それぞれ均質燃焼時の
燃料噴射時期、成層燃焼時の燃料噴射時期を算出する。The intake stroke injection amount calculation unit H and the compression stroke injection amount calculation unit I calculate the total fuel injection amount per stroke calculated by the fuel injection amount calculation unit F by the distribution ratio calculation unit G. Based on the distribution ratio, the fuel injection amount is distributed between the fuel injection amount in the intake stroke and the fuel injection amount in the compression stroke. The homogeneous injection timing calculation unit J and the stratified injection timing calculation unit K calculate the fuel injection timing during homogeneous combustion and the fuel injection timing during stratified combustion, respectively.

【００２７】噴射パルス生成部Ｌは、前記均質燃焼噴射
時期算出部Ｊで算出された均質燃焼用の噴射時期に前記
吸気行程での燃料噴射量に対応したパルス幅の燃料噴射
パルスを生成し、同様に前記成層燃焼噴射時期算出部Ｋ
で算出された成層燃焼用の噴射時期に前記圧縮行程での
燃料噴射量に対応したパルス幅の燃料噴射パルスを生成
する。The injection pulse generator L generates a fuel injection pulse having a pulse width corresponding to the fuel injection amount in the intake stroke at the injection timing for homogeneous combustion calculated by the homogeneous combustion injection timing calculator J. Similarly, the stratified combustion injection timing calculator K
A fuel injection pulse having a pulse width corresponding to the fuel injection amount in the compression stroke is generated at the injection timing for stratified combustion calculated in (1).

【００２８】これにより、燃焼切換時には、前記配分率
で吸気行程と圧縮行程とに前記配分率で配分された量の
燃料が噴射され、二回噴射が行なわれる。次に、前記燃
料噴射量の配分率を設定するルーチンを、図４のフロー
チャートに従い、図５のタイムチャートを参照しつつ説
明する。このルーチンは、所定時間例えば10ｍｓ毎に実
行される。Thus, at the time of the combustion switching, the fuel is injected in the amount distributed at the distribution ratio in the intake stroke and the compression stroke at the distribution ratio, and the fuel is injected twice. Next, a routine for setting the distribution rate of the fuel injection amount will be described with reference to a flowchart of FIG. 4 and a time chart of FIG. This routine is executed every predetermined time, for example, every 10 ms.

【００２９】ステップ１では機関の回転速度，負荷等の
運転条件に基づいて、成層燃焼，均質燃焼のいずれかを
選択する（均質／成層判定部) 。ステップ２では、いず
れの燃焼が選択されたか否かを判定する（切換部) 。ス
テップ２で成層燃焼が選択された場合は、ステップ３へ
進んで成層燃焼用の当量比をマップからの検索等により
算出する（成層当量比算出部) 。In step 1, either stratified combustion or homogeneous combustion is selected based on operating conditions such as the engine speed and load (homogeneous / stratified judging section). In step 2, it is determined whether any combustion has been selected (switching unit). If stratified combustion is selected in step 2, the process proceeds to step 3 to calculate a stratified combustion equivalent ratio by searching a map or the like (stratified equivalent ratio calculation unit).

【００３０】ステップ２で均質燃焼が選択された場合
は、ステップ４へ進んで均質燃焼用の当量比をマップか
らの検索等により算出する（均質当量比算出部) 。ステ
ップ５では、前記算出された当量比を遅れ処理するとき
の加重平均の現在値に対する重みＦｌｏａｄを、機関の
運転条件例えば機関回転速度Ｎとスロットル弁開度ＴＶ
Ｏとに基づいてマップ（図６参照) からの検索等により
算出する。If the homogeneous combustion is selected in step 2, the process proceeds to step 4 where the equivalent ratio for homogeneous combustion is calculated by searching a map or the like (homogeneous equivalent ratio calculating section). In step 5, the weight Fload with respect to the current value of the weighted average when the calculated equivalence ratio is delayed is determined according to the engine operating conditions such as the engine speed N and the throttle valve opening TV.
Based on O, it is calculated by retrieval from a map (see FIG. 6) or the like.

【００３１】ステップ６では、前記重みＦｌｏａｄを用
いて、当量比Ｔφを次式により加重平均して遅れ処理す
る（遅延部) 。 Ｔφｄ＝Ｔφn ×Ｆｌｏａｄ＋Ｔφn-1 ×（１−Ｆｌｏ
ａｄ) 例えば、成層燃焼から均質燃焼へ判定が切り換えられる
と、図５に示すように当量比が成層燃焼用のマップ値か
ら遅れ処理により徐々に増大して均質燃焼用の目標値に
近づけられる。In step 6, using the weight Fload, the equivalent ratio Tφ is weighted and averaged according to the following equation to perform delay processing (delay section). Tφd = Tφn × Fload + Tφn−1 × (1-Flo
ad) For example, when the determination is switched from stratified combustion to homogeneous combustion, as shown in FIG. 5, the equivalent ratio gradually increases from the map value for stratified combustion by delay processing and approaches the target value for homogeneous combustion.

【００３２】図４に戻ってステップ７では、次式により
燃料噴射量Ｔｅを算出する（燃料噴射量算出部) 。 Ｔｅ＝Ｔｐ×Ｔφｄ×Ｋtr×Ｋtw×Ｋas×（α＋αｍ) ここで、Ｔｐは、エアフロメータで検出された吸入空気
量Ｑ，機関回転速度Ｎにより得られる基本燃料噴射量
（＝ｋＱ／Ｎ；ｋは定数) 、Ｋtrは過渡補正係数, Ｋtw
は水温補正係数, Ｋasは始動後増量補正係数, αは空燃
比フィードバック補正係数, αｍは該空燃比フィードバ
ック補正係数αの学習値である。Returning to FIG. 4, in step 7, the fuel injection amount Te is calculated by the following equation (fuel injection amount calculation unit). Te = Tp × Tφd × Ktr × Ktw × Kas × (α + αm) Here, Tp is a basic fuel injection amount (= kQ / N; k) obtained from the intake air amount Q detected by the air flow meter and the engine rotation speed N. Is a constant), Ktr is the transient correction coefficient, Ktw
Is a water temperature correction coefficient, Kas is a post-start increase correction coefficient, α is an air-fuel ratio feedback correction coefficient, and αm is a learned value of the air-fuel ratio feedback correction coefficient α.

【００３３】ステップ８では、成層燃焼用の燃料噴射時
期ITS と、均質燃焼用の燃料噴射時期ITS とを、機関の
回転速度Ｎと負荷に基づいて各燃焼毎のマップ（図７,
図８参照) ４からの検索等によって算出する。ステップ
９では、均質燃焼用の燃料噴射時期ITS をセットする。
ステップ10では、前記遅れ処理された当量比Ｔφｄが、
均質燃焼時の下限値ＴφＨより所定値α１だけ小さい均
質燃焼切換用判定値より大きいか否かを判定する。そし
て、該判定値より大きいと判定された場合は、ステップ
11へ進んで均質燃焼への配分率を100 ％とし、ステップ
７で算出された燃料噴射量Ｔｅを全て吸気行程で噴射し
て完全な均質燃焼を行なわせる。In step 8, the fuel injection timing ITS for stratified combustion and the fuel injection timing ITS for homogeneous combustion are mapped for each combustion based on the engine speed N and the load (FIG. 7).
(Refer to FIG. 8). In step 9, the fuel injection timing ITS for homogeneous combustion is set.
In step 10, the delayed equivalent ratio Tφd is
It is determined whether or not the value is greater than a homogeneous combustion switching determination value that is smaller than the lower limit value TφH during homogeneous combustion by a predetermined value α1. If it is determined that the value is larger than the determination value,
Proceeding to 11, the distribution ratio to homogeneous combustion is set to 100%, and the fuel injection amount Te calculated in step 7 is all injected in the intake stroke to perform complete homogeneous combustion.

【００３４】ステップ10で当量比Ｔφｄが均質燃焼切換
用判定値以下であると判定されたときはステップ12へ進
み、該当量比Ｔφｄが成層燃焼時の上限値ＴφＳより所
定値α２だけ大きい成層燃焼切換用判定値より小さいか
否かを判定する。そして、該判定値より小さいと判定さ
れた場合は、ステップ13へ進んで均質燃焼への配分率を
０％、つまり成層燃焼への配分率を100 ％とし、前記燃
料噴射量Ｔｅを全て圧縮行程で噴射して完全な成層燃焼
を行なわせる。When it is determined in step 10 that the equivalence ratio Tφd is equal to or less than the determination value for switching to homogeneous combustion, the process proceeds to step 12, in which the corresponding ratio Tφd is larger than the upper limit value TφS during stratified combustion by a predetermined value α2. It is determined whether it is smaller than the switching determination value. If it is determined that it is smaller than the determination value, the routine proceeds to step 13, where the distribution ratio to homogeneous combustion is set to 0%, that is, the distribution ratio to stratified combustion is set to 100%, and the fuel injection amount Te is entirely reduced in the compression stroke. To perform complete stratified combustion.

【００３５】また、ステップ12で当量比Ｔφｄが成層燃
焼切換用判定値より小さいと判定されたとき、つまり、
当量比ＴφｄがＴφＳ＋α２＜Ｔφｄ＜ＴφＨ−α１の
範囲にあるときは、本発明に係る燃焼切換時の状態であ
って、かつ、吸気行程と圧縮行程とで２回燃料を噴射す
るときであると判断して、ステップ14以降へ進み２回噴
射を実行する。If it is determined in step 12 that the equivalence ratio Tφd is smaller than the stratified combustion switching determination value, that is,
When the equivalence ratio Tφd is in the range of TφS + α2 <Tφd <TφH-α1, it is the state of the combustion switching according to the present invention, and it is the time of injecting the fuel twice in the intake stroke and the compression stroke. After making a determination, the process proceeds to step 14 and the subsequent steps to execute two injections.

【００３６】ステップ14では、当量比Ｔφｄを成層燃焼
用下限値ＴφＳと均質燃焼用上限値ＴφＨとで内分した
比率を次式により算出する。 Ｔφｄ内分比＝（Ｔφｄ−ＴφＳ) ／（ＴφＨ−Ｔφ
ｄ) なお、当量比Ｔφｄを成層燃焼切換用判定値ＴφＳ＋α
２と、均質燃焼切換用判定値ＴφＨ−α１とで内分し
て、内分比（＝０〜１) を算出してもよい。In step 14, a ratio obtained by internally dividing the equivalent ratio Tφd by the stratified combustion lower limit TφS and the homogeneous combustion upper limit TφH is calculated by the following equation. Tφd internal division ratio = (Tφd−TφS) / (TφH−Tφ
d) Note that the equivalence ratio Tφd is determined by the stratified combustion switching determination value TφS + α.
2 and the homogeneous combustion switching determination value TφH−α1, the internal division ratio (= 0 to 1) may be calculated.

【００３７】ステップ15では、前記当量比Ｔφｄの内分
比に基づいて、前記均質燃焼を基準とする燃料噴射量の
配分率を、図９に示したようなテーブルから検索する。
該均質燃焼の燃料配分率は、当量比Ｔφｄが増大するほ
ど増大するが、０より相当量大きい最小値から100 ％よ
り相当量小さい最大値の範囲に設定される。これは、吸
気行程又は圧縮行程での燃料噴射量が小さくなり過ぎる
と燃料噴射弁による燃料噴射量の精度が維持できなくな
るためである。In step 15, based on the internal division ratio of the equivalence ratio Tφd, the distribution ratio of the fuel injection amount based on the homogeneous combustion is retrieved from a table as shown in FIG.
The fuel distribution rate of the homogeneous combustion increases as the equivalence ratio Tφd increases, but is set in a range from a minimum value considerably larger than 0 to a maximum value considerably smaller than 100%. This is because if the fuel injection amount in the intake stroke or the compression stroke becomes too small, the accuracy of the fuel injection amount by the fuel injection valve cannot be maintained.

【００３８】このように、燃焼に切換に応じて当量比を
徐々に切り換える期間中に分割噴射を行うことにより、
この間の燃焼性を安定させることができ、失火の発生を
防止できる。特に、本実施の形態では、当量比の範囲で
分割噴射期間を設定し、かつ、切換前後の燃焼の当量比
から所定の偏差を有する当量比範囲で設定してあるた
め、リッチ過剰やリーン過剰となることを防止して確実
に安定した燃焼を確保できる。また、アイドル時等でエ
アコン負荷の投入等により成層燃焼から理論空燃比での
均質ストイキ燃焼に切り換えられる場合、該理論空燃比
相当の当量比（＝１) からの偏差は、機関回転速度に基
づいて設定する。均質燃焼のリーン限界当量比は、機関
回転速度によって定まるためである。As described above, by performing the split injection during the period in which the equivalent ratio is gradually switched in accordance with the switching to the combustion,
The flammability during this period can be stabilized, and the occurrence of misfire can be prevented. Particularly, in the present embodiment, the split injection period is set within the range of the equivalent ratio, and is set within the equivalent ratio range having a predetermined deviation from the equivalent ratio of the combustion before and after the switching. And stable combustion can be reliably ensured. Further, when switching from stratified combustion to homogeneous stoichiometric combustion at the stoichiometric air-fuel ratio by inputting an air-conditioner load or the like during idling, the deviation from the equivalent ratio (= 1) corresponding to the stoichiometric air-fuel ratio is based on the engine speed. To set. This is because the lean equivalent ratio of homogeneous combustion is determined by the engine speed.

【００３９】なお、燃焼の切換判断に応じてスロットル
弁開度を制御し（例えば図５の例では成層燃焼から均質
燃焼への切換判断時にスロットル弁開度を減少制御) 、
これに応じてシリンダ吸入空気量が徐々に変化する（図
５の例では漸減) 。また、トルクは、吸入空気量の遅れ
に応じて当量比を徐々に変化させる制御により、略一定
に維持される。また、点火時期（進角値) は、分割噴射
期間中は基本的に成層燃焼を行うので成層燃焼に合わせ
て設定しつつ当量比の変化に応じて緩やかに変化させ
（図５の例では均質燃焼に近づくにつれて緩やかに遅
角) る。そして、分割噴射と１回噴射による均質燃焼へ
の切換に同期してステップ的に変化させ（均質燃焼への
切換時に進角) 、均質燃焼時の当量比変化期間中は緩や
かに変化させる制御とする。The throttle valve opening is controlled in accordance with the combustion switching judgment (for example, in the example of FIG. 5, the throttle valve opening is controlled to decrease when judging the switching from stratified combustion to homogeneous combustion).
In response, the cylinder intake air amount gradually changes (in the example of FIG. 5, gradually decreases). Further, the torque is maintained substantially constant by the control of gradually changing the equivalent ratio according to the delay of the intake air amount. In addition, since the ignition timing (advance value) basically performs stratified charge combustion during the split injection period, it is set in accordance with the stratified charge combustion and is gradually changed according to the change in the equivalence ratio (in the example of FIG. (Slowly retards as combustion approaches). Then, the control is changed stepwise in synchronization with the switching to the homogeneous combustion by the divided injection and the single injection (advance angle at the time of switching to the homogeneous combustion), and gradually changed during the equivalent ratio change period during the homogeneous combustion. I do.

【００４０】次に、上記のようにして算出された燃料噴
射量の配分率に従って実行される燃料噴射制御ルーチン
を、図10のフローチャートに従って説明する。このルー
チンは、均質燃焼の燃料噴射時期ITS となったときに実
行される。ステップ21では、前記配分率が100 ％か否か
を判定する。100 ％でない場合は、ステップ22へ進み同
じく配分率が０％か否かを判定する。０％でもない場合
は、２回噴射を行なう場合であり、ステップ23以降へ進
む。Next, a fuel injection control routine executed in accordance with the fuel injection amount distribution ratio calculated as described above will be described with reference to the flowchart of FIG. This routine is executed when the fuel injection timing ITS for homogeneous combustion has come. In step 21, it is determined whether or not the distribution ratio is 100%. If it is not 100%, the process proceeds to step 22, and it is determined whether the distribution rate is 0%. If it is not 0%, it means that the injection is performed twice, and the process proceeds to step 23 and subsequent steps.

【００４１】ステップ23では、吸気行程時の燃料噴射量
（燃料噴射弁に出力されるパルス幅) Ｔｉ１を次式によ
り算出する。 Ｔｉ１＝Ｔｅ×配分率＋Ｔｓ ここで、Ｔｓは燃料噴射弁の開弁に要する無効噴射分で
ある。ステップ24では、圧縮行程時の燃料噴射量Ｔｉ２
を次式により算出する。In step 23, the fuel injection amount (pulse width output to the fuel injection valve) Ti1 during the intake stroke is calculated by the following equation. Ti1 = Te × distribution rate + Ts Here, Ts is an invalid injection amount required to open the fuel injection valve. In step 24, the fuel injection amount Ti2 during the compression stroke
Is calculated by the following equation.

【００４２】Ｔｉ２＝Ｔｅ×（１−配分率) ＋Ｔｓ 次いでステップ25へ進み、別ルーチンで算出された成層
燃焼用の点火時期ＡＤＶＳをセットする。２回噴射の場
合の燃焼は基本的には成層燃焼であるため、成層燃焼用
の点火時期ＡＤＶＳを使用するのである。ステップ26で
は、前記吸気行程での燃料噴射時期ITH で燃料噴射量Ｔ
ｉの噴射が開始される。Ti2 = Te × (1−distribution ratio) + Ts Then, the routine proceeds to step 25, where the ignition timing ADVS for stratified combustion calculated by another routine is set. Since the combustion in the case of the double injection is basically stratified combustion, the ignition timing ADVS for stratified combustion is used. In step 26, at the fuel injection timing ITH in the intake stroke, the fuel injection amount T
The injection of i is started.

【００４３】ステップ27で、成層燃焼用の燃料噴射時期
ITS をセットし、ステップ28で前記圧縮行程での燃料噴
射量Ｔｉ２をセットする。これにより、圧縮行程での成
層燃焼用の燃料噴射時期ITS で燃料噴射量Ｔｉ２の燃料
噴射が開始される。また、ステップ21で配分率が100 ％
と判定された場合は完全な均質燃焼を行なう場合であ
り、ステップ29へ進んで次式に示すように、均質燃焼用
の吸気行程で噴射される燃料噴射量Ｔｉ１を算出すると
共に、成層燃焼用の圧縮行程で噴射される燃料噴射量Ｔ
ｉ２を０に設定する。In step 27, the fuel injection timing for stratified combustion
ITS is set, and in step 28, the fuel injection amount Ti2 in the compression stroke is set. Thus, the fuel injection of the fuel injection amount Ti2 is started at the fuel injection timing ITS for stratified combustion in the compression stroke. In step 21, the allocation rate is 100%
When it is determined that the combustion is completely homogeneous, the routine proceeds to step 29, where the fuel injection amount Ti1 injected in the intake stroke for homogeneous combustion is calculated and the stratified combustion Fuel injection amount T injected in the compression stroke of
Set i2 to 0.

【００４４】Ｔｉ１＝Ｔｅ（×100 ％) ＋Ｔｓ Ｔｉ２＝０ 次いで、ステップ30へ進んで、別ルーチンで算出された
均質燃焼用の点火時期ＡＤＶＨをセットした後、前記ス
テップ25以降へ進む。これにより、該点火時期で点火を
行って均質燃焼を行う。Ti1 = Te (× 100%) + Ts Ti2 = 0 Next, the routine proceeds to step 30, where the ignition timing ADVH for homogeneous combustion calculated by another routine is set, and thereafter, the routine proceeds to step 25 and thereafter. Thereby, ignition is performed at the ignition timing to perform homogeneous combustion.

【００４５】また、ステップ２で配分率が０％と判定さ
れた場合は、完全な成層燃焼を行なう場合であり、ステ
ップ31へ進んで次式に示すように、均質燃焼用の吸気行
程で噴射される燃料噴射量Ｔｉ１を０に設定すると共
に、成層燃焼用の圧縮行程で噴射される燃料噴射量Ｔｉ
２を算出する。 Ｔｉ１＝０ Ｔｉ２＝Ｔｅ（×100 ％) ＋Ｔｓ 次いで、ステップ25へ進み、成層燃焼用の点火時期ＡＤ
ＶＳをセットした後、該点火時期で点火を行ない成層燃
焼を行う。If it is determined in step 2 that the distribution ratio is 0%, this means that complete stratified combustion is to be performed. The routine proceeds to step 31, where the injection is performed in the intake stroke for homogeneous combustion as shown in the following equation. The set fuel injection amount Ti1 is set to 0, and the fuel injection amount Ti injected in the compression stroke for stratified combustion is set.
2 is calculated. Ti1 = 0 Ti2 = Te (× 100%) + Ts Next, the routine proceeds to step 25, where the ignition timing AD for stratified combustion is obtained.
After setting VS, ignition is performed at the ignition timing to perform stratified combustion.

【００４６】図11は、所定時間例えば10ｍｓ毎に実行さ
れる点火時期算出ルーチンのフローを示し、ステップ31
で機関の運転条件例えば機関回転速度Ｎと基本燃料噴射
量Ｔｐ等の負荷とに基づいて均質燃焼用の点火時期ＡＤ
ＶＨを算出し、ステップ32では同様にして成層燃焼用の
点火時期ＡＤＶＳを算出する。FIG. 11 shows the flow of an ignition timing calculation routine executed every predetermined time, for example, every 10 ms.
And the ignition timing AD for homogeneous combustion based on the engine operating conditions such as the engine speed N and the load such as the basic fuel injection amount Tp.
VH is calculated, and in step 32, the ignition timing ADVS for stratified combustion is calculated in the same manner.

【図面の簡単な説明】[Brief description of the drawings]

【図１】 本発明の構成を示す機能ブロック図。FIG. 1 is a functional block diagram showing a configuration of the present invention.

【図２】 本発明の一実施形態を示すシステム図。FIG. 2 is a system diagram showing an embodiment of the present invention.

【図３】 同上の実施形態に係る制御の機能を示すブロ
ック図。FIG. 3 is a block diagram showing a control function according to the embodiment.

【図４】 同じく分割噴射時における吸気行程と圧縮行
程との燃料量の配分率を算出するルーチンを示すフロー
チャート。FIG. 4 is a flowchart showing a routine for calculating a distribution ratio of a fuel amount between an intake stroke and a compression stroke during the split injection.

【図５】 同じく成層燃焼から均質燃焼に切り換える場
合の各種状態の変化を示すタイムチャート。FIG. 5 is a time chart showing changes in various states when switching from stratified combustion to homogeneous combustion.

【図６】 同じく当量比を変化させるときの加重平均演
算の重み付けを設定したマップ。FIG. 6 is a map in which weights for weighted average calculation when the equivalent ratio is changed are set.

【図７】 同じく均質燃焼用の点火時期を設定したマッ
プ。FIG. 7 is also a map in which ignition timing for homogeneous combustion is set.

【図８】 同じく成層燃焼用の点火時期を設定したマッ
プ。FIG. 8 is also a map in which the ignition timing for stratified combustion is set.

【図９】 同じく前記配分率を設定したマップ。FIG. 9 is a map in which the distribution ratio is set.

【図10】 同じく燃料噴射制御ルーチンを示すフローチ
ャート。FIG. 10 is a flowchart showing a fuel injection control routine.

【図11】 同じく各燃焼用の点火時期を算出するルーチ
ンを示すフローチャート。FIG. 11 is a flowchart showing a routine for calculating an ignition timing for each combustion.

【符号の説明】[Explanation of symbols]

１ 内燃機関 ４ 電制スロットル弁 ５ 燃料噴射弁 ６ 点火栓 20 コントロールユニット DESCRIPTION OF SYMBOLS 1 Internal combustion engine 4 Electric throttle valve 5 Fuel injection valve 6 Spark plug 20 Control unit

───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 ＦＩ Ｆ０２Ｄ 41/34 Ｆ０２Ｄ 41/34 Ｅ 45/00 ３７６ 45/00 ３７６Ｃ Ｆ０２Ｐ 5/15 Ｆ０２Ｐ 5/15 Ｂ (72)発明者 中島 祐樹 神奈川県横浜市神奈川区宝町２番地 日産 自動車株式会社内────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code FI F02D 41/34 F02D 41/34 E 45/00 376 45/00 376C F02P 5/15 F02P 5/15 B (72) Inventor Nakajima Yuki 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture Nissan Motor Co., Ltd.

Claims (6)

【特許請求の範囲】[Claims] 【請求項１】シリンダ内に燃料を噴射供給する直接噴射
式内燃機関において、機関の運転状態に基づいて、吸気
行程で比較的リッチな当量比となるように燃料を供給す
る均質燃焼条件と、圧縮行程で比較的リーンな当量比と
なるように燃料を供給する成層燃焼条件とを判別し、前
記均質燃焼条件と成層燃焼条件との判別が切り換わった
ときに、前記リッチな当量比とリーンな当量比との間で
当量比を徐々に切り換えると共に、該切換期間中の少な
くとも所定期間、吸気行程と圧縮行程との両方に分けて
燃料を供給するようにしたことを特徴とする内燃機関の
燃料噴射制御装置。In a direct injection type internal combustion engine for injecting fuel into a cylinder, a homogeneous combustion condition for supplying fuel so as to have a relatively rich equivalent ratio in an intake stroke based on an operation state of the engine; The stratified combustion condition for supplying fuel is determined so as to have a relatively lean equivalent ratio in the compression stroke. When the determination between the homogeneous combustion condition and the stratified combustion condition is switched, the rich equivalent ratio and the lean The internal combustion engine is characterized in that the equivalence ratio is gradually switched between the equivalence ratio and at least a predetermined period during the switching period, and fuel is supplied separately to both the intake stroke and the compression stroke. Fuel injection control device. 【請求項２】シリンダ内に燃料を噴射供給する直接噴射
式内燃機関において、機関の運転状態を検出する運転状
態検出手段と、検出された運転状態に基づいて、吸気行
程で比較的リッチな当量比となるように燃料を供給する
均質燃焼条件と、圧縮行程で比較的リーンな当量比とな
るように燃料を供給する成層燃焼条件とを判別する燃焼
条件判別手段と、前記均質燃焼条件と成層燃焼条件との
判別が切り換わったときに、前記リッチな当量比とリー
ンな当量比との間で当量比を徐々に切り換える当量比切
換手段と、前記当量比切換手段による当量比の切換期間
中の少なくとも所定期間、吸気行程と圧縮行程との両方
に分けて燃料を供給する燃料分割供給手段と、を含んで
構成したことを特徴とする内燃機関の燃料噴射制御装
置。2. In a direct injection type internal combustion engine for injecting fuel into a cylinder, an operating state detecting means for detecting an operating state of the engine, and an equivalent amount relatively rich in an intake stroke based on the detected operating state. A combustion condition determining means for determining a homogeneous combustion condition for supplying fuel so as to obtain a ratio and a stratified combustion condition for supplying fuel so as to have a relatively lean equivalent ratio in a compression stroke; and An equivalence ratio switching means for gradually switching the equivalence ratio between the rich equivalence ratio and the lean equivalence ratio when the determination of the combustion condition is switched, and during an equivalence ratio switching period by the equivalence ratio switching means. Fuel supply control means for supplying fuel separately for both the intake stroke and the compression stroke for at least a predetermined period of time. 【請求項３】成層燃焼から均質燃焼への切換時において
前記燃料を両行程に分けて供給する条件は、前記燃焼の
切換要求が発生してから、該均質燃焼に対応した点火時
期の切換が行なわれるまでの間であることを特徴とする
請求項１又は請求項２に記載の内燃機関の燃料噴射制御
装置。3. The condition for supplying the fuel in two strokes at the time of switching from stratified combustion to homogeneous combustion is that the ignition timing corresponding to the homogeneous combustion is switched after the combustion switching request is generated. The fuel injection control device for an internal combustion engine according to claim 1 or 2, wherein the control is performed until the operation is performed. 【請求項４】前記燃料を両行程に分けて供給する条件
は、所定の当量比範囲とすることを特徴とする請求項１
〜請求項３のいずれか１つに記載の内燃機関の燃料噴射
制御装置。4. The fuel supply system according to claim 1, wherein the condition in which the fuel is supplied in two strokes is a predetermined equivalence ratio range.
The fuel injection control device for an internal combustion engine according to any one of claims 1 to 3. 【請求項５】前記燃料を両行程に分けて供給する条件
は、前記徐々に切り換えられる当量比が、切換前の燃焼
条件における当量比に対し所定値以上の偏差を有してか
ら、切換後の燃焼条件における当量比に対し所定値以下
の偏差となるまでとすることを特徴とする請求項１〜請
求項４のいずれか１つに記載の内燃機関の燃料噴射制御
装置。5. The condition for supplying the fuel in two strokes is that the gradually switched equivalent ratio has a deviation equal to or more than a predetermined value from the equivalent ratio under the combustion conditions before switching, The fuel injection control device for an internal combustion engine according to any one of claims 1 to 4, wherein the deviation is equal to or less than a predetermined value with respect to the equivalence ratio under the combustion condition. 【請求項６】均質燃焼条件が理論空燃比での燃焼である
場合、該理論空燃比相当の当量比に対し、前記所定値は
機関回転速度に基づいて設定されることを特徴とする請
求項５に記載の内燃機関の燃料噴射制御装置。6. When the homogeneous combustion condition is combustion at a stoichiometric air-fuel ratio, the predetermined value is set based on an engine speed with respect to an equivalent ratio corresponding to the stoichiometric air-fuel ratio. 6. The fuel injection control device for an internal combustion engine according to claim 5.
JP17623997A 1997-07-01 1997-07-01 Fuel injection control device for internal combustion engine Expired - Lifetime JP3677947B2 (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
JP17623997A JP3677947B2 (en) 1997-07-01 1997-07-01 Fuel injection control device for internal combustion engine
KR1019980025490A KR100317159B1 (en) 1997-07-01 1998-06-30 Fuel injection control system for internal combustion engine
DE69838199T DE69838199T2 (en) 1997-07-01 1998-06-30 Fuel injection control system for internal combustion engines
EP98112067A EP0889218B1 (en) 1997-07-01 1998-06-30 Fuel injection control system for internal combustion engine
US09/108,409 US6058905A (en) 1997-07-01 1998-07-01 Fuel injection control system for internal combustion engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP17623997A JP3677947B2 (en) 1997-07-01 1997-07-01 Fuel injection control device for internal combustion engine

Publications (2)

Publication Number Publication Date
JPH1122508A true JPH1122508A (en) 1999-01-26
JP3677947B2 JP3677947B2 (en) 2005-08-03

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ID=16010080

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Application Number Title Priority Date Filing Date
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Country Link
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10146504B4 (en) * 2000-09-21 2010-01-07 Honda Giken Kogyo K.K. Ignition timing control apparatus and ignition timing control method for internal combustion engines
JP2012233456A (en) * 2011-05-09 2012-11-29 Mitsubishi Electric Corp Internal combustion engine control device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10146504B4 (en) * 2000-09-21 2010-01-07 Honda Giken Kogyo K.K. Ignition timing control apparatus and ignition timing control method for internal combustion engines
JP2012233456A (en) * 2011-05-09 2012-11-29 Mitsubishi Electric Corp Internal combustion engine control device

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