JP4483706B2 - In-cylinder direct injection spark ignition internal combustion engine controller - Google Patents

In-cylinder direct injection spark ignition internal combustion engine controller Download PDF

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JP4483706B2
JP4483706B2 JP2005158511A JP2005158511A JP4483706B2 JP 4483706 B2 JP4483706 B2 JP 4483706B2 JP 2005158511 A JP2005158511 A JP 2005158511A JP 2005158511 A JP2005158511 A JP 2005158511A JP 4483706 B2 JP4483706 B2 JP 4483706B2
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fuel
internal combustion
combustion engine
direct injection
dead center
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JP2006336477A (en
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彰 中島
智之 武田
智之 茂藤
泰三 堀込
仁 石井
全幸 富田
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Nissan Motor Co Ltd
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    • Y02T10/46—

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

この発明は、筒内に燃料を直接に噴射する筒内直接噴射式火花点火内燃機関に関し、特に、排気系の触媒コンバータの早期昇温（早期活性化）が要求される冷間始動時などにおける噴射時期および点火時期の制御に関する。   The present invention relates to an in-cylinder direct injection type spark ignition internal combustion engine that directly injects fuel into a cylinder, and in particular, at a cold start in which early temperature rise (early activation) of an exhaust system catalytic converter is required. It relates to control of injection timing and ignition timing.

特許文献１には、筒内直接噴射式火花点火内燃機関の触媒暖機方法として、排気浄化用の触媒コンバータが活性温度よりも低い未暖機状態のときに、吸気行程から点火時期にかけての期間内で、部分的な空燃比の濃淡を有する混合気を燃焼室内に形成する後期噴射と、この後期噴射より前に燃料を噴射して、後期噴射の燃料と後期噴射の燃焼とで延焼可能な、理論空燃比よりもリーンな空燃比の混合気を燃焼室内に生成する早期噴射と、の少なくとも２回の分割噴射を行い、かつ点火時期をＭＢＴ点より所定量リタードさせるとともに、機関の無負荷領域では点火時期を圧縮上死点よりも前に設定し、無負荷領域を除く低速低負荷領域では点火時期を圧縮上死点以降までリタードさせる技術が記載されている。上記後期噴射は、圧縮行程の中期以降、例えば１２０°ＢＴＤＣ〜４５°ＢＴＤＣに行われる。
特許第３３２５２３０号公報 In Patent Document 1, as a catalyst warm-up method for a direct injection spark ignition internal combustion engine, a period from an intake stroke to an ignition timing when the exhaust gas catalytic converter is in an unwarmed state lower than an activation temperature. In this case, it is possible to spread the fuel by the late injection in which the air-fuel mixture having a partial air-fuel ratio concentration is formed in the combustion chamber, the fuel is injected before this late injection, and the fuel of the late injection and the combustion of the late injection And at least two split injections of early injection for generating an air-fuel mixture leaner than the stoichiometric air-fuel ratio in the combustion chamber, and retarding the ignition timing by a predetermined amount from the MBT point, and no engine load A technique is described in which the ignition timing is set before the compression top dead center in the region, and the ignition timing is retarded until the compression top dead center in the low speed and low load region excluding the no-load region. The latter-stage injection is performed after the middle of the compression stroke, for example, at 120 ° BTDC to 45 ° BTDC.
Japanese Patent No. 3325230

内燃機関の冷機時における触媒の早期活性化および後燃えによるＨＣ低減のためには、点火時期の遅角が有効であり、より大きな効果を得るためには、圧縮上死点以降の点火（ＡＴＤＣ点火）が望ましい。ＡＴＤＣ点火で安定した燃焼を行わせるためには、燃焼期間を短縮する必要があり、そのために、筒内の乱れを強化して、燃焼速度（火炎伝播速度）を上昇させることが必要である。   For early activation of the catalyst when the internal combustion engine is cold and HC reduction due to afterburning, retarding the ignition timing is effective. To obtain a greater effect, ignition after compression top dead center (ATDC) Ignition) is desirable. In order to perform stable combustion by ATDC ignition, it is necessary to shorten the combustion period. For this reason, it is necessary to increase the combustion speed (flame propagation speed) by strengthening the turbulence in the cylinder.

このような乱れの強化のために、筒内に高圧で噴射される燃料噴霧のエネルギにより筒内に乱れを生成することが考えられる。   In order to strengthen such disturbance, it is conceivable that the disturbance is generated in the cylinder by the energy of the fuel spray injected at a high pressure in the cylinder.

しかしながら、特許文献１では、主に、１回目の燃料噴射（早期噴射）を吸気行程中に行い、２回目の燃料噴射（後期噴射）を圧縮行程中の１２０°ＢＴＤＣ〜４５°ＢＴＤＣに行っている。このように最後の燃料噴射が圧縮上死点よりも前では、その噴霧により筒内に乱れを生成しても、圧縮上死点以降はその乱れが減衰してしまい、ＡＴＤＣ点火での火炎伝播速度上昇には寄与しない。   However, in Patent Document 1, the first fuel injection (early injection) is performed during the intake stroke, and the second fuel injection (late injection) is performed from 120 ° BTDC to 45 ° BTDC during the compression stroke. Yes. As described above, before the last fuel injection is before the compression top dead center, even if the spray generates turbulence in the cylinder, the turbulence is attenuated after the compression top dead center, and the flame propagation in ATDC ignition Does not contribute to speed increase.

例えば、図６は、吸気ポート内に設けたガス流動制御弁（例えばタンブル制御弁）を作動させた場合とこのようなガス流動制御弁を具備しない場合とについて、筒内の乱れの大きさを示したものであるが、ガス流動制御弁を作動させることで吸気行程中に生成した乱れ（符号Ａの部分）は、圧縮行程の進行とともに減衰し、圧縮行程後期のタンブル流の崩壊に伴い一時的に乱れが大きくなる（符号Ｂの部分）ものの、圧縮上死点以降は符号Ｃで示すように急速に減衰してしまい、その乱れを用いた燃焼改善（火炎伝播向上）はあまり期待できない。燃料噴霧による乱れについても同様であり、圧縮上死点より前の燃料噴射により乱れが生成されたとしても、圧縮上死点以降の点火燃焼には寄与しない。   For example, FIG. 6 shows the magnitude of turbulence in a cylinder when a gas flow control valve (for example, a tumble control valve) provided in an intake port is operated and when such a gas flow control valve is not provided. As shown, the turbulence (part A) generated during the intake stroke by operating the gas flow control valve attenuates with the progress of the compression stroke, and is temporarily accompanied by the collapse of the tumble flow in the latter half of the compression stroke. Although the turbulence increases (the portion indicated by reference symbol B), after the compression top dead center, as shown by the reference symbol C, it rapidly attenuates, and combustion improvement (improving flame propagation) using the turbulence cannot be expected so much. The same applies to turbulence caused by fuel spray, and even if turbulence is generated by fuel injection before compression top dead center, it does not contribute to ignition combustion after compression top dead center.

このため、ＡＴＤＣ点火の方が排温上昇やＨＣ低減に有利であるが、燃焼安定性が成立しないため、特許文献１では、無負荷領域では点火時期を圧縮上死点前（ＢＴＤＣ点火）としている。   Therefore, ATDC ignition is more advantageous for exhaust temperature rise and HC reduction, but combustion stability is not established. Therefore, in Patent Document 1, the ignition timing is set to before compression top dead center (BTDC ignition) in the no-load region. Yes.

本発明は、このような実状を踏まえて、触媒の早期活性化およびＨＣ低減などのためのＡＴＤＣ点火での燃焼安定性を改善することを目的としている。   The present invention aims to improve the combustion stability in ATDC ignition for early activation of the catalyst, reduction of HC, and the like based on such a situation.

この発明は、筒内に直接燃料を噴射する燃料噴射弁および点火プラグを備えるとともに、上記燃料噴射弁へ供給される燃圧を可変制御する燃圧可変手段を備え、圧縮行程中に燃料を噴射するとともに圧縮上死点前に点火を行うことで成層希薄燃焼を実現する筒内直接噴射式火花点火内燃機関の制御装置において、例えば触媒コンバータの冷機時のような排気ガス温度の昇温が要求されたときに、点火時期を圧縮上死点後に設定するとともに、この点火時期前でかつ圧縮上死点後に燃料を噴射する超リタード燃焼を行う一方、上記燃圧を、上記の成層希薄燃焼時よりも高く補正することを特徴としている。なお、ＮＯｘを吸着するＮＯｘトラップ触媒においては、硫黄成分（ＳＯｘ）が触媒に付着することによりＮＯｘ吸着性能が低下するので、触媒を強制的に高温化してＳＯｘを放出するＳＯｘ放出処理（硫黄被毒解除）を行う必要があるが、このＳＯｘ放出処理の際の排気ガス温度の昇温を、上記の超リタード燃焼を利用して行うことも可能である。 The present invention is provided with a fuel injection valve and the spark plug for directly injecting fuel into a cylinder, comprising a fuel pressure varying means for variably controlling the fuel pressure supplied to the fuel injection valve, as well as injecting the fuel during the compression stroke a control apparatus for a cylinder direct injection spark ignition internal combustion engine to realize the stratified charge lean combustion by performing the ignition to the compression top dead center, Atsushi Nobori of the exhaust gas temperature, such as when the catalytic converter cold is required if e example The ignition timing is set after the compression top dead center, and super retard combustion is performed before the ignition timing and after the compression top dead center, while the fuel pressure is set higher than that in the stratified lean combustion. It is characterized by high correction. In the NOx trap catalyst that adsorbs NOx, the sulfur component (SOx) adheres to the catalyst, so that the NOx adsorption performance deteriorates. However, it is also possible to raise the temperature of the exhaust gas during the SOx release process using the above-mentioned super retard combustion.

超リタード燃焼における燃圧は、望ましくは、負荷が大きいほど高くなる。特に、超リタード燃焼における燃圧と成層希薄燃焼時の同負荷での燃圧との差が、負荷が大きいほど拡大することが望ましい。   The fuel pressure in the super retard combustion is desirably higher as the load is larger. In particular, it is desirable that the difference between the fuel pressure in super retard combustion and the fuel pressure at the same load during stratified lean combustion increases as the load increases.

すなわち、圧縮上死点以降では、吸気行程や圧縮行程で生成された乱れは減衰してしまうが、圧縮上死点以降の膨張行程中になされる燃料噴射によって、筒内の乱れを生成・強化することができ、ＡＴＤＣ点火での火炎伝播が促進される。従って、点火時期を圧縮上死点後とした超リタード燃焼が安定的に成立する。特に本発明では、超リタード燃焼の際に、通常の成層希薄燃焼のための圧縮行程噴射のときよりも燃圧を高く設定し、高圧で噴射することにより、噴霧自体のエネルギによって筒内に微小な乱れを積極的に生成することができ、乱れによる活発な燃焼が得られる。従って、圧縮上死点よりも遅角した点火時期でもって、安定した燃焼が可能であり、燃焼安定度の上で制限される点火時期の遅角限界が、より遅角側となる。そのため、点火時期の大幅な遅角により、排気ガス温度を大幅に昇温させることができ、かつＨＣ排出量が低減する。   In other words, after the compression top dead center, the turbulence generated in the intake stroke and the compression stroke is attenuated, but the in-cylinder turbulence is generated and strengthened by the fuel injection performed during the expansion stroke after the compression top dead center. Flame propagation with ATDC ignition is facilitated. Therefore, super retard combustion with the ignition timing after the compression top dead center is established stably. In particular, in the present invention, the fuel pressure is set higher during the ultra retard combustion than in the compression stroke injection for normal stratified lean combustion, and the fuel is injected at a high pressure. Turbulence can be actively generated, and active combustion due to the turbulence can be obtained. Therefore, stable combustion is possible with the ignition timing retarded from the compression top dead center, and the retard limit of the ignition timing that is limited in terms of combustion stability is on the retard side. For this reason, the exhaust gas temperature can be raised significantly by a large retardation of the ignition timing, and the HC emission amount is reduced.

また負荷が上昇すると、空気量の増加に伴い上死点での筒内圧が高くなるが、この負荷上昇に伴って燃圧を高く補正するようにすれば、筒内圧に対抗し得るように噴霧の貫徹力が上昇し、高い筒内圧の中でも、噴霧による乱れの生成が可能である。なお、一般に、成層希薄燃焼による圧縮行程噴射の場合にも、負荷が上昇したときに燃料噴射期間が過度に長くならないように、負荷が高いほど燃圧を高くする燃圧制御が行われるが、貫徹力の上昇を図るためには、同じ負荷で比較したときの成層希薄燃焼時の燃圧と超リタード燃焼の燃圧との差つまり補正量が、負荷が大きいほど拡大していることが望ましい。   As the load increases, the cylinder pressure at the top dead center increases as the air volume increases.If the fuel pressure is corrected to be higher as the load increases, the spray pressure can be controlled to counter the cylinder pressure. Penetrating force is increased, and turbulence due to spraying can be generated even in high in-cylinder pressure. In general, even in the case of compression stroke injection by stratified lean combustion, fuel pressure control is performed so that the fuel pressure increases as the load increases so that the fuel injection period does not become excessively long when the load increases. In order to increase this, it is desirable that the difference between the fuel pressure in stratified lean combustion and the fuel pressure in super retarded combustion, that is, the correction amount, when compared with the same load, is increased as the load increases.

この発明によれば、点火時期を圧縮上死点後に設定した超リタード燃焼の燃焼安定性を十分に確保することができ、例えば冷間始動の際に、触媒の早期活性化および後燃えによるＨＣ低減を達成することができる。   According to the present invention, it is possible to sufficiently ensure the combustion stability of the super retard combustion in which the ignition timing is set after the compression top dead center. For example, at the time of cold start, the catalyst is activated early and the HC due to the afterburning. Reduction can be achieved.

以下、この発明の一実施例を図面に基づいて詳細に説明する。   Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

図１は、この発明が適用される筒内直接噴射式火花点火内燃機関のシステム構成を示す構成説明図である。   FIG. 1 is a configuration explanatory view showing a system configuration of a direct injection type spark ignition internal combustion engine to which the present invention is applied.

この内燃機関１のピストン２により形成される燃焼室３には、吸気弁（図示せず）を介して吸気通路４が接続され、かつ排気弁（図示せず）を介して排気通路５が接続されている。上記吸気通路４には、吸入空気量を検出するエアフロメータ６が配設されているとともに、制御信号によりアクチュエータ８を介して開度制御される電子制御スロットル弁７が配設されている。排気通路５には、排気浄化用の触媒コンバータ１０が配設されているとともに、その上流側および下流側にそれぞれ空燃比センサ１１，１２が設けられており、さらに、上流側の空燃比センサ１１と並んで、触媒コンバータ１０入口側での排気温度を検出する排気温度センサ１３が設けられている。   An intake passage 4 is connected to the combustion chamber 3 formed by the piston 2 of the internal combustion engine 1 via an intake valve (not shown), and an exhaust passage 5 is connected via an exhaust valve (not shown). Has been. The intake passage 4 is provided with an air flow meter 6 for detecting the amount of intake air, and an electronically controlled throttle valve 7 whose opening degree is controlled via an actuator 8 by a control signal. The exhaust passage 5 is provided with a catalytic converter 10 for purifying exhaust gas, and air-fuel ratio sensors 11 and 12 are provided on the upstream side and the downstream side, respectively. Further, the upstream air-fuel ratio sensor 11 is provided. Is provided with an exhaust gas temperature sensor 13 for detecting the exhaust gas temperature at the inlet side of the catalytic converter 10.

燃焼室３の中央頂上部には、点火プラグ１４が配置されている。また、燃焼室３の吸気通路４側の側部に、該燃焼室３内に燃料を直接噴射する燃料噴射弁１５が配置されている。この燃料噴射弁１５には、高圧燃料ポンプ１６およびプレッシャレギュレータ１７によって所定圧力に調圧された燃料が、高圧燃料通路１８を介して供給されている。従って、各気筒の燃料噴射弁１５が制御パルスにより開弁することで、その開弁期間に応じた量の燃料が噴射される。なお、１９は、燃圧を検出する燃圧センサ、２０は、上記高圧燃料ポンプ１６へ燃料を送る低圧燃料ポンプである。ここで、上記プレッシャレギュレータ１７は、燃圧可変手段として、燃料噴射弁１５に供給される燃料の燃圧を、比較的広い範囲で変化させることができる構成となっている。   A spark plug 14 is disposed at the central top of the combustion chamber 3. A fuel injection valve 15 that directly injects fuel into the combustion chamber 3 is disposed on the side of the combustion chamber 3 on the intake passage 4 side. The fuel that has been regulated to a predetermined pressure by the high-pressure fuel pump 16 and the pressure regulator 17 is supplied to the fuel injection valve 15 via the high-pressure fuel passage 18. Therefore, when the fuel injection valve 15 of each cylinder is opened by the control pulse, an amount of fuel corresponding to the valve opening period is injected. Reference numeral 19 denotes a fuel pressure sensor that detects the fuel pressure, and 20 denotes a low-pressure fuel pump that sends fuel to the high-pressure fuel pump 16. Here, the pressure regulator 17 is configured to change the fuel pressure of the fuel supplied to the fuel injection valve 15 within a relatively wide range as the fuel pressure varying means.

また内燃機関１には、機関冷却水温を検出する水温センサ２１が設けられているとともに、クランク角を検出するクランク角センサ２２が設けられている。さらに、運転者によるアクセルペダル踏み込み量を検出するアクセル開度センサ２３が設けられている。   In addition, the internal combustion engine 1 is provided with a water temperature sensor 21 for detecting the engine cooling water temperature and a crank angle sensor 22 for detecting a crank angle. Further, an accelerator opening sensor 23 is provided for detecting the amount of depression of the accelerator pedal by the driver.

上記内燃機関１の燃料噴射量や噴射時期、燃圧、点火時期、等は、コントロールユニット２５によって制御される。このコントロールユニット２５には、上述した各種のセンサ類の検出信号が入力されている。コントロールユニット２５は、これらの入力信号により検出される機関運転条件に応じて、燃焼方式つまり均質燃焼とするか成層燃焼とするかを決定するとともに、これに合わせて、電子制御スロットル弁７の開度、燃料噴射弁１５の燃料噴射時期および燃料噴射量、点火プラグ１４の点火時期、プレッシャレギュレータ１７による燃圧、等を制御する。   The fuel injection amount, injection timing, fuel pressure, ignition timing, etc. of the internal combustion engine 1 are controlled by the control unit 25. The control unit 25 receives detection signals from the various sensors described above. The control unit 25 determines the combustion method, that is, the homogeneous combustion or the stratified combustion, in accordance with the engine operating conditions detected by these input signals, and according to this, the electronic control throttle valve 7 is opened. The fuel injection timing and fuel injection amount of the fuel injection valve 15, the ignition timing of the spark plug 14, the fuel pressure by the pressure regulator 17, and the like are controlled.

暖機完了後においては、低速低負荷側の所定の領域では、通常の成層燃焼運転として、圧縮行程の適宜な時期に燃料噴射が行われ、かつ圧縮上死点前の時期に点火が行われる。燃料噴霧は点火プラグ１４近傍に層状に集められ、これにより、空燃比を３０〜４０程度とした極リーンの成層燃焼が実現される。このとき、燃料噴射弁１５から噴射される燃料の燃圧は、燃料噴射量の増加に対し燃料噴射期間が過度に長くならないように、図３の特性ａに示すように、負荷の上昇に伴って徐々に高くなる所定の特性に沿って制御される。また、高速高負荷側の所定の領域では、通常の均質燃焼運転として、吸気行程中に燃料噴射が行われ、かつ圧縮上死点前のＭＢＴ点近傍において点火が行われる。この場合は、燃料は筒内で均質な混合気となる。この均質燃焼運転としては、運転条件に応じて、空燃比を理論空燃比とした均質ストイキ燃焼と、空燃比を２０〜３０程度のリーンとした均質リーン燃焼と、がある。   After the warm-up is completed, in a predetermined region on the low-speed and low-load side, as normal stratified combustion operation, fuel injection is performed at an appropriate time in the compression stroke, and ignition is performed before the compression top dead center. . The fuel spray is collected in the vicinity of the spark plug 14, thereby achieving extremely lean stratified combustion with an air-fuel ratio of about 30 to 40. At this time, the fuel pressure of the fuel injected from the fuel injection valve 15 is increased as the load increases as shown by the characteristic a in FIG. 3 so that the fuel injection period does not become excessively long as the fuel injection amount increases. Control is performed along predetermined characteristics that gradually increase. Further, in a predetermined region on the high speed and high load side, as normal homogeneous combustion operation, fuel injection is performed during the intake stroke, and ignition is performed in the vicinity of the MBT point before the compression top dead center. In this case, the fuel becomes a homogeneous mixture in the cylinder. As the homogeneous combustion operation, there are homogeneous stoichiometric combustion in which the air-fuel ratio is the stoichiometric air-fuel ratio and homogeneous lean combustion in which the air-fuel ratio is lean about 20 to 30 depending on the operating conditions.

本発明は、触媒コンバータ１０の早期昇温が要求される内燃機関１の冷間始動時において、排気温度を高温とするように、超リタード燃焼を行うものであり、以下、この超リタード燃焼の燃料噴射時期および点火時期を図２に基づいて説明する。   The present invention performs super retard combustion so that the exhaust gas temperature becomes high at the time of cold start of the internal combustion engine 1 where early temperature rise of the catalytic converter 10 is required. The fuel injection timing and ignition timing will be described with reference to FIG.

図２は、超リタード燃焼の３つの実施例を示しており、実施例１では、点火時期を１５°〜３０°ＡＴＤＣ（例えば２０°ＡＴＤＣ）とし、燃料噴射時期（詳しくは燃料噴射開始時期）を、圧縮上死点以降でかつ点火時期前に設定する。なお、このとき、空燃比は、理論空燃比ないしはこれよりも若干リーン（１６〜１７程度）に設定される。また、燃料噴霧による乱れの生成が得られるように、プレッシャレギュレータ１７により制御される燃圧が、上述した通常の成層燃焼運転のときよりも十分に高く与えられる。   FIG. 2 shows three examples of super retard combustion. In Example 1, the ignition timing is set to 15 ° to 30 ° ATDC (for example, 20 ° ATDC), and the fuel injection timing (specifically, the fuel injection start timing) is shown. Is set after the compression top dead center and before the ignition timing. At this time, the air-fuel ratio is set to the stoichiometric air-fuel ratio or slightly lean (about 16 to 17). Further, the fuel pressure controlled by the pressure regulator 17 is given sufficiently higher than that in the above-described normal stratified combustion operation so that turbulence is generated by fuel spray.

すなわち、触媒暖機促進ならびにＨＣ低減のためには、点火時期遅角が有効であり、上死点以降の点火（ＡＴＤＣ点火）が望ましいが、ＡＴＤＣ点火で安定した燃焼を行わせるためには、燃焼期間を短縮する必要があり、そのためには、乱れによる火炎伝播を促進しなければならない。前述したように、圧縮上死点以降では、吸気行程や圧縮行程で生成された乱れは減衰してしまうが、本発明では、圧縮上死点以降の膨張行程中になされる高圧の燃料噴射によって、ガス流動が生じ、これにより筒内の乱れを生成・強化することができる。従って、ＡＴＤＣ点火での火炎伝播が促進され、安定した燃焼が可能となる。図４は、噴霧自体によって筒内に生成される微小な乱れと燃圧との関係を示したものであり、図示するように、燃圧が高いほど乱れが活発に生成される。   That is, in order to promote catalyst warm-up and reduce HC, ignition timing retardation is effective, and ignition after top dead center (ATDC ignition) is desirable, but in order to perform stable combustion with ATDC ignition, It is necessary to shorten the combustion period, and for this purpose, flame propagation due to turbulence must be promoted. As described above, after the compression top dead center, the turbulence generated in the intake stroke and the compression stroke is attenuated, but in the present invention, by the high pressure fuel injection performed during the expansion stroke after the compression top dead center. The gas flow is generated, and thereby the turbulence in the cylinder can be generated and strengthened. Therefore, flame propagation by ATDC ignition is promoted and stable combustion is possible. FIG. 4 shows the relationship between the minute turbulence generated in the cylinder by the spray itself and the fuel pressure. As shown, the turbulence is actively generated as the fuel pressure is higher.

図２の実施例２は、燃料噴射を２回に分割した例であり、１回目の燃料噴射を吸気行程中に行い、２回目の燃料噴射を圧縮上死点以降に行う。なお、点火時期や空燃比（２回の噴射を合わせた空燃比）および燃圧は実施例１と同様である。   The second embodiment in FIG. 2 is an example in which the fuel injection is divided into two, and the first fuel injection is performed during the intake stroke, and the second fuel injection is performed after the compression top dead center. The ignition timing, air-fuel ratio (air-fuel ratio including two injections), and fuel pressure are the same as in the first embodiment.

このように、圧縮上死点後の燃料噴射（膨張行程噴射）に先立ち、吸気行程中に燃料噴射（吸気行程噴射）を行うと、吸気行程噴射の燃料噴霧による乱れは圧縮行程後半で減衰してしまい、圧縮上死点後におけるガス流動強化には殆ど影響を与えないが、噴射燃料が燃焼室全体に拡散していて、ＡＴＤＣ点火によるＨＣの後燃えの促進に寄与するので、ＨＣ低減および排温上昇には有効である。   Thus, if fuel injection (intake stroke injection) is performed during the intake stroke prior to fuel injection after compression top dead center (expansion stroke injection), the disturbance due to fuel spray in the intake stroke injection is attenuated in the latter half of the compression stroke. However, since the injected fuel is diffused throughout the combustion chamber and contributes to the promotion of HC afterburning by ATDC ignition, the HC reduction and It is effective for raising the exhaust temperature.

また、図２の実施例３は、燃料噴射を２回に分割し、１回目の燃料噴射を圧縮行程にて行い、２回目の燃料噴射を圧縮上死点以降に行う。このように、圧縮上死点後の燃料噴射（膨張行程噴射）に先立ち、圧縮行程中に燃料噴射（圧縮行程噴射）を行うと、実施例２の吸気行程噴射に比べれば、圧縮行程噴射の方が、その燃料噴霧による乱れの減衰が遅くなるため、この１回目の燃料噴射による乱れが残り、圧縮上死点以降に２回目の燃料噴射を行うことで、１回目の燃料噴射で生成した乱れを助長するように乱れを強化でき、圧縮上死点付近における更なるガス流動強化が図れる。   In the third embodiment of FIG. 2, the fuel injection is divided into two, the first fuel injection is performed in the compression stroke, and the second fuel injection is performed after the compression top dead center. As described above, when the fuel injection (compression stroke injection) is performed during the compression stroke prior to the fuel injection after the compression top dead center (expansion stroke injection), the compression stroke injection is compared with the intake stroke injection of the second embodiment. However, since the disturbance of the turbulence due to the fuel spray is delayed, the turbulence due to the first fuel injection remains, and the second fuel injection is performed after the compression top dead center, which is generated by the first fuel injection. The turbulence can be strengthened to promote the turbulence, and the gas flow can be further strengthened near the compression top dead center.

この実施例３の場合に、１回目の圧縮行程噴射は、圧縮行程前半でもよいが、圧縮行程後半（９０°ＢＴＤＣ以降）に設定すると、上死点付近での乱れをより高めることができる。特に、この１回目の圧縮行程噴射を、４５°ＢＴＤＣ以降、より望ましくは２０°ＢＴＤＣ以降とすると、圧縮上死点以降のガス流動をより強化することができる。   In the case of Example 3, the first compression stroke injection may be in the first half of the compression stroke, but if it is set in the second half of the compression stroke (after 90 ° BTDC), the disturbance near the top dead center can be further increased. In particular, if the first compression stroke injection is 45 ° BTDC or later, more desirably 20 ° BTDC or later, the gas flow after compression top dead center can be further enhanced.

このように、実施例１〜３の超リタード燃焼によれば、点火の直前に高圧の燃料噴霧により筒内の乱れを生成・強化することができ、火炎伝播を促進して、安定した燃焼を行わせることができる。特に、点火時期を１５°〜３０°ＡＴＤＣまで遅角させることにより、触媒の早期活性化およびＨＣ低減のための十分な後燃え効果を得ることができる。換言すれば、このように点火時期を大きく遅らせても、その直前まで燃料噴射を遅らせて、乱れの生成時期も遅らせることで、火炎伝播向上による燃焼改善を達成できるのである。   Thus, according to the super retarded combustion of Examples 1 to 3, turbulence in the cylinder can be generated and strengthened by high-pressure fuel spray just before ignition, and flame propagation is promoted to achieve stable combustion. Can be done. In particular, by retarding the ignition timing from 15 ° to 30 ° ATDC, a sufficient afterburning effect for early activation of the catalyst and reduction of HC can be obtained. In other words, even if the ignition timing is greatly delayed in this way, the fuel injection is delayed until just before that, and the generation time of the turbulence is also delayed, so that the combustion improvement by improving the flame propagation can be achieved.

一方、上記の超リタード燃焼の際の燃圧は、負荷の変化に対し、図３のｂのような特性でもって制御される。すなわち、全体として、負荷が大きいほど燃圧が高くなる特性を有しているとともに、通常の成層燃焼運転のときの燃圧ａを基準としたときの補正量ΔＰ（換言すれば同じ負荷に対する超リタード燃焼時の燃圧ｂと通常の成層燃焼運転時の燃圧ａとの差）が、負荷が大きいほど拡大している。図３の特性ｃは、参考例として、通常の成層燃焼運転時の燃圧ａを基準として一定の補正量を加えた場合の燃圧特性を示しているが、このような燃圧ｃに比較して、高負荷側ほどより高くなるように燃圧が補正される。   On the other hand, the fuel pressure at the time of the above-mentioned super retard combustion is controlled with the characteristic as shown in FIG. That is, as a whole, the fuel pressure increases as the load increases, and the correction amount ΔP based on the fuel pressure a during normal stratified combustion operation (in other words, super retard combustion for the same load) The difference between the fuel pressure b at the time and the fuel pressure a during the normal stratified combustion operation) increases as the load increases. As a reference example, the characteristic c in FIG. 3 shows the fuel pressure characteristic when a certain correction amount is added with reference to the fuel pressure a during normal stratified combustion operation, but compared with such a fuel pressure c, The fuel pressure is corrected so that the higher the load side, the higher the fuel pressure.

図５は、負荷が低いときの筒内圧変化と負荷が大きいときの筒内圧変化とを対比して示したものであり、図示するように、負荷が上昇すると、空気量の増加に伴い上死点での筒内圧が高くなる。このような筒内圧の上昇に対し、本実施例では、図３の特性ｂのように負荷上昇に伴って燃圧が高く与えられるので、筒内圧力に対抗し得るように噴霧の貫徹力が上昇し、高い筒内圧の中で、点火プラグ１４近傍に最適混合気を確実に形成することができるとともに、噴霧自体のエネルギによる乱れがより活発に生成される。   FIG. 5 shows a comparison between a change in the in-cylinder pressure when the load is low and a change in the in-cylinder pressure when the load is large. The cylinder pressure at the point increases. In contrast to such an increase in the in-cylinder pressure, in this embodiment, the fuel pressure is increased as the load increases as shown by the characteristic b in FIG. 3, so that the penetration force of the spray increases so as to counter the in-cylinder pressure. In addition, an optimum air-fuel mixture can be reliably formed in the vicinity of the spark plug 14 in a high in-cylinder pressure, and disturbance due to the energy of the spray itself is generated more actively.

なお、本発明の超リタード燃焼は、排気系の触媒コンバータ１０としてＮＯｘトラップ触媒を用いた場合の硫黄被毒解除のためにも利用することができる。ＮＯｘトラップ触媒は、流入する排気の排気空燃比がリーンであるときにＮＯｘを吸着し、流入する排気の排気空燃比がリッチであると、吸着していたＮＯｘを放出して触媒作用により浄化処理するものであるが、燃料中の硫黄成分（ＳＯｘ）が触媒に結合するとＮＯｘ吸着性能が低下する。そのため、適当な時期に、触媒を強制的に高温化してＳＯｘを放出除去する処理（いわゆる硫黄被毒解除）が必要である。本発明の超リタード燃焼は、非常に高い排気温度を得られるので、このＮＯｘトラップ触媒の硫黄被毒解除処理に適したものとなる。   The super retarded combustion of the present invention can also be used for releasing sulfur poisoning when a NOx trap catalyst is used as the exhaust system catalytic converter 10. The NOx trap catalyst adsorbs NOx when the exhaust air-fuel ratio of the inflowing exhaust gas is lean, and releases the adsorbed NOx when the exhaust air-fuel ratio of the inflowing exhaust gas is rich, and purifies by catalytic action. However, when the sulfur component (SOx) in the fuel is bound to the catalyst, the NOx adsorption performance is lowered. For this reason, it is necessary to perform a process (so-called sulfur poisoning release) for forcibly raising the temperature of the catalyst and releasing SOx at an appropriate time. The super retarded combustion according to the present invention can obtain a very high exhaust temperature, and therefore is suitable for the sulfur poisoning release processing of this NOx trap catalyst.

本発明に係る内燃機関全体のシステム構成を示す構成説明図。BRIEF DESCRIPTION OF THE DRAWINGS The structure explanatory drawing which shows the system structure of the whole internal combustion engine which concerns on this invention. 本発明の超リタード燃焼の燃料噴射時期および点火時期を示す特性図。The characteristic view which shows the fuel injection timing and ignition timing of the super retard combustion of this invention. この実施例の負荷に対する燃圧の特性を示す特性図。The characteristic view which shows the characteristic of the fuel pressure with respect to the load of this Example. 噴霧により生成される微小な乱れと燃圧との関係を示す特性図。The characteristic view which shows the relationship between the minute disturbance produced | generated by spraying, and fuel pressure. 負荷の大小による筒内圧変化を示す特性図。The characteristic view which shows the in-cylinder pressure change by the magnitude of load. 従来技術における筒内の乱れの変化を示す説明図。Explanatory drawing which shows the change of the disturbance in a cylinder in a prior art.

符号の説明Explanation of symbols

３…燃焼室
１０…触媒コンバータ
１３…排気温度センサ
１４…点火プラグ
１５…燃料噴射弁
１７…プレッシャレギュレータ
２５…コントロールユニット DESCRIPTION OF SYMBOLS 3 ... Combustion chamber 10 ... Catalytic converter 13 ... Exhaust temperature sensor 14 ... Spark plug 15 ... Fuel injection valve 17 ... Pressure regulator 25 ... Control unit

Claims (8)

筒内に直接燃料を噴射する燃料噴射弁および点火プラグを備えるとともに、上記燃料噴射弁へ供給される燃圧を可変制御する燃圧可変手段を備え、圧縮行程中に燃料を噴射するとともに圧縮上死点前に点火を行うことで成層希薄燃焼を実現する筒内直接噴射式火花点火内燃機関の制御装置において、排気ガス温度の昇温が要求されたときに、点火時期を圧縮上死点後に設定するとともに、この点火時期前でかつ圧縮上死点後に燃料を噴射する超リタード燃焼を行う一方、上記燃圧を、上記の成層希薄燃焼時よりも高く補正することを特徴とする筒内直接噴射式火花点火内燃機関の制御装置。 A fuel injection valve that directly injects fuel into the cylinder and a spark plug, and fuel pressure variable means that variably controls the fuel pressure supplied to the fuel injection valve, inject fuel during the compression stroke, and compression top dead center In the control device for an in-cylinder direct injection spark ignition internal combustion engine that realizes stratified lean combustion by performing ignition before , when the exhaust gas temperature needs to be raised , the ignition timing is set after compression top dead center In addition, in-cylinder direct injection spark characterized by performing super retard combustion in which fuel is injected before the ignition timing and after compression top dead center, while the fuel pressure is corrected to be higher than that in the stratified lean combustion. Control device for an ignition internal combustion engine. 超リタード燃焼における点火時期は、圧縮上死点後１５°〜３０°ＣＡであることを特徴とする請求項１に記載の筒内直接噴射式火花点火内燃機関の制御装置。   2. The control apparatus for a direct injection spark ignition internal combustion engine according to claim 1, wherein the ignition timing in the super retard combustion is 15 ° to 30 ° CA after compression top dead center. 超リタード燃焼においては、圧縮上死点後の燃料噴射に先だって、吸気行程中もしくは圧縮行程中に、さらに燃料噴射を行うことを特徴とする請求項１または２に記載の筒内直接噴射式火花点火内燃機関の制御装置。   The in-cylinder direct injection spark according to claim 1 or 2, wherein in super retard combustion, fuel injection is further performed during an intake stroke or a compression stroke prior to fuel injection after compression top dead center. Control device for an ignition internal combustion engine. 超リタード燃焼における空燃比は、理論空燃比もしくは若干リーンであることを特徴とする請求項１〜３のいずれかに記載の筒内直接噴射式火花点火内燃機関の制御装置。   The control apparatus for a direct injection spark ignition internal combustion engine according to any one of claims 1 to 3, wherein the air-fuel ratio in super retarded combustion is a stoichiometric air-fuel ratio or slightly lean. 超リタード燃焼における燃圧は、負荷が大きいほど高くなることを特徴とする請求項１〜４のいずれかに記載の筒内直接噴射式火花点火内燃機関の制御装置。   The control apparatus for a direct injection spark ignition internal combustion engine according to any one of claims 1 to 4, wherein the fuel pressure in the super retard combustion increases as the load increases. 超リタード燃焼における燃圧と成層希薄燃焼時の同負荷での燃圧との差が、負荷が大きいほど拡大することを特徴とする請求項５に記載の筒内直接噴射式火花点火内燃機関の制御装置。   6. The control device for a direct injection spark ignition internal combustion engine according to claim 5, wherein the difference between the fuel pressure in super retard combustion and the fuel pressure at the same load during stratified lean combustion increases as the load increases. . 排気系の触媒コンバータの早期昇温が要求される内燃機関の冷間始動時に、上記の排気ガス温度の昇温が要求されることを特徴とする請求項１〜６のいずれかに記載の筒内直接噴射式火花点火内燃機関の制御装置。 The cylinder according to any one of claims 1 to 6, wherein the temperature of the exhaust gas is required to be raised during a cold start of the internal combustion engine that requires an early temperature increase of the exhaust system catalytic converter. Control device for internal direct injection spark ignition internal combustion engine. 排気系の触媒コンバータのＳＯｘ放出処理を行うときに、上記の排気ガス温度の昇温が要求されることを特徴とする請求項１〜６のいずれかに記載の筒内直接噴射式火花点火内燃機関の制御装置。 When performing the SOx release process of a catalytic converter in the exhaust system, cylinder direct injection spark ignition internal combustion according to any one of claims 1 to 6, characterized in that heating of the exhaust gas temperature is required Engine control device.
JP2005158511A 2005-05-31 2005-05-31 In-cylinder direct injection spark ignition internal combustion engine controller Expired - Fee Related JP4483706B2 (en)

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JP2005158511A JP4483706B2 (en) 2005-05-31 2005-05-31 In-cylinder direct injection spark ignition internal combustion engine controller
EP06011017A EP1728995A3 (en) 2005-05-31 2006-05-29 Combustion control method and apparatus for a direct injection spark ignition internal combustion engine
US11/443,178 US7350504B2 (en) 2005-05-31 2006-05-31 Control apparatus and method for inner cylinder direct injection spark ignited internal combustion engine
CN 200610087674 CN1880745B (en) 2005-05-31 2006-05-31 Control apparatus and method for inner cylinder direct injection spark ignited internal combustion engine

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JP4918911B2 (en) * 2007-12-25 2012-04-18 日産自動車株式会社 Fuel pressure control device for in-cylinder direct fuel injection spark ignition engine
US8447503B2 (en) * 2009-05-19 2013-05-21 GM Global Technology Operations LLC Control strategy for operating a homogeneous-charge compression-ignition engine subsequent to a fuel cutoff event
US8899209B2 (en) 2010-10-08 2014-12-02 Ford Global Technologies, Llc System and method for compensating cetane
US8051829B2 (en) * 2010-10-08 2011-11-08 Ford Global Technologies, Llc Method for controlling low temperature combustion
JP2012154209A (en) * 2011-01-24 2012-08-16 Hitachi Automotive Systems Ltd Internal combustion engine control device, and internal combustion engine
JP2012172666A (en) * 2011-02-24 2012-09-10 Mazda Motor Corp Control device of spark-ignition type gasoline engine
JP5978662B2 (en) * 2012-03-09 2016-08-24 マツダ株式会社 Control device for diesel engine with turbocharger
JP6260580B2 (en) * 2015-05-11 2018-01-17 トヨタ自動車株式会社 Control device for internal combustion engine
JP6555322B2 (en) * 2017-11-10 2019-08-07 マツダ株式会社 Control device for compression ignition engine
JP7283450B2 (en) * 2020-07-07 2023-05-30 トヨタ自動車株式会社 engine device

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