JP2006002683A - Control device for internal combustion engine - Google Patents

Control device for internal combustion engine Download PDF

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JP2006002683A
JP2006002683A JP2004180546A JP2004180546A JP2006002683A JP 2006002683 A JP2006002683 A JP 2006002683A JP 2004180546 A JP2004180546 A JP 2004180546A JP 2004180546 A JP2004180546 A JP 2004180546A JP 2006002683 A JP2006002683 A JP 2006002683A
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ignition combustion
self
ignition
combustion mode
internal combustion
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Masanori Kurosawa
雅徳 黒澤
Seiichiro Nishikawa
誠一郎 西川
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Denso Corp
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Denso Corp
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    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/10Internal combustion engine [ICE] based vehicles
    • Y02T10/12Improving ICE efficiencies

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  • 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

<P>PROBLEM TO BE SOLVED: To improve purification rate of exhaust gas, increase output torque and suppress torque fluctuation at a time of combustion mode change while securing fuel economy improving effect of self ignition combustion. <P>SOLUTION: Combustion mode is switched to a normal ignition combustion mode and a specific cylinder self ignition combustion mode according to engine operation condition. In the specific cylinder self ignition combustion mode, air fuel ration is made lean and self ignition combustion is performed in the specific cylinder, air fuel ratio is made rich and normal ignition combustion is performed in remaining cylinders to control air fuel ratio of exhaust gas at an exhaust gas collecting part 24 to be stoichiometric. Consequently, purification rate of exhaust gas is improved by controlling air fuel ratio of exhaust gas in a purification window of a catalyst 25 while securing fuel economy improving effect by self ignition combustion of the specific cylinder. Moreover, output torque is increased by performing normal ignition combustion which can materialize high output in remaining cylinders and torque fluctuation at a time of combustion mode change is suppressed by lessening torque difference with normal ignition combustion mode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、筒内の混合気を圧縮により自着火させて燃焼させる自着火燃焼と、筒内の混合気を点火手段で点火して火炎伝播燃焼させる通常点火燃焼とを切り換えて運転する内燃機関の制御装置に関するものである。   The present invention relates to an internal combustion engine that operates by switching between self-ignition combustion in which an air-fuel mixture in a cylinder is self-ignited by compression and combustion, and normal ignition combustion in which the air-fuel mixture in the cylinder is ignited by an ignition means and flame propagation combustion is performed. This relates to the control device.

車両に搭載されるガソリンエンジンにおいては、空燃比をストイキよりもリーンにして自着火燃焼を実施することで燃費向上とNOx排出量低減を実現できることが知られている。そこで、エンジン運転状態に応じて、燃費向上とNOx排出量低減を実現できる自着火燃焼モードと、高出力を実現できる通常点火燃焼モードとを切り換えることが提案されている。例えば、特許文献1(特開2002−256872号公報)では、低中負荷・低中回転領域では自着火燃焼モードで運転し、低中負荷・低中回転領域以外の領域では通常点火燃焼モードで運転することが提案されている。また、特許文献2(特開2003−129848号公報)では、低速・低負荷領域では自着火燃焼モードで運転し、高速・高負荷領域では通常点火燃焼モードで運転することが提案されている。
特開2002−256872号公報(第2頁等) 特開2003−129848号公報(第2頁等)
In a gasoline engine mounted on a vehicle, it is known that fuel efficiency improvement and NOx emission reduction can be realized by performing auto-ignition combustion with an air-fuel ratio leaner than stoichiometric. Therefore, it has been proposed to switch between a self-ignition combustion mode that can improve fuel consumption and reduce NOx emissions and a normal ignition combustion mode that can achieve high output in accordance with the engine operating state. For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-256872), operation is performed in a self-ignition combustion mode in a low / medium load / low / medium rotation region, and normal ignition combustion mode is performed in a region other than the low / medium load / low / medium rotation region. It has been proposed to drive. Patent Document 2 (Japanese Patent Application Laid-Open No. 2003-129848) proposes operating in the auto-ignition combustion mode in the low speed / low load region and operating in the normal ignition combustion mode in the high speed / high load region.
JP 2002-256872 A (the second page etc.) Japanese Unexamined Patent Publication No. 2003-129848 (second page, etc.)

しかし、空燃比をリーンにして自着火燃焼を実施する自着火燃焼モードでは、排出ガスの空燃比がリーンになって三元触媒等の触媒の浄化ウインド(ストイキ付近)から外れてしまうため、触媒の排出ガス浄化率が低下するという問題がある。また、自着火燃焼モードは、通常点火燃焼モードに比べて燃焼が短期間で終了するため、有効なトルクが発生する時間が短く、出力トルクが不足しやすいという問題がある。更に、自着火燃焼モードは、通常点火燃焼モードに比べて出力トルクが小さいため、燃焼モードを切り換える際のトルク変動が大きくなるという問題もある。   However, in the self-ignition combustion mode in which the self-ignition combustion is performed with the air-fuel ratio being lean, the air-fuel ratio of the exhaust gas becomes lean and deviates from the purification window (near the stoichiometric) of a catalyst such as a three-way catalyst. There is a problem that the exhaust gas purification rate is reduced. In addition, the self-ignition combustion mode has a problem that since the combustion is completed in a shorter period than the normal ignition combustion mode, the time for generating effective torque is short, and the output torque tends to be insufficient. Furthermore, since the self-ignition combustion mode has a smaller output torque than the normal ignition combustion mode, there is also a problem that torque fluctuation when switching the combustion mode becomes large.

本発明は、これらの事情を考慮してなされたものであり、従って本発明の目的は、自着火燃焼による燃費向上効果及びNOx排出量低減効果を確保しながら、排出ガス浄化率向上と出力トルク増大を実現できると共に、燃焼モード切換時のトルク変動を抑制することができる内燃機関の制御装置を提供することにある。   The present invention has been made in consideration of these circumstances. Accordingly, the object of the present invention is to improve the exhaust gas purification rate and output torque while ensuring the fuel efficiency improvement effect and NOx emission reduction effect by self-ignition combustion. An object of the present invention is to provide a control device for an internal combustion engine that can realize an increase and suppress torque fluctuations at the time of switching a combustion mode.

上記目的を達成するために、本発明の請求項1に記載の内燃機関の制御装置は、筒内の混合気を圧縮により自着火させて燃焼させる自着火燃焼と、筒内の混合気を点火手段で点火して火炎伝播燃焼させる通常点火燃焼とを切り換えて運転するシステムにおいて、特定気筒自着火燃焼モード制御手段によって、特定の気筒で空燃比をストイキよりもリーンにして自着火燃焼を実施すると共に残りの気筒で空燃比をストイキよりもリッチにして通常点火燃焼を実施する特定気筒自着火燃焼モードで運転することで、排気管集合部における排出ガスの空燃比がほぼストイキになるように制御するようにしたものである。   In order to achieve the above object, a control device for an internal combustion engine according to claim 1 of the present invention includes self-ignition combustion in which an air-fuel mixture in a cylinder is self-ignited by compression and burns, and an air-fuel mixture in the cylinder is ignited. In a system that operates by switching between normal ignition combustion that ignites by means of flame propagation combustion, the specific cylinder self-ignition combustion mode control means performs the self-ignition combustion with the air-fuel ratio leaner than the stoichiometric in the specific cylinder At the same time, the air-fuel ratio of the remaining cylinders is made richer than stoichiometric, and operation is performed in a specific cylinder auto-ignition combustion mode in which normal ignition combustion is performed, so that the air-fuel ratio of the exhaust gas in the exhaust pipe collecting part is controlled to be almost stoichiometric. It is what you do.

この特定気筒自着火燃焼モードでは、特定の気筒で空燃比をリーンにして自着火燃焼を実施するため、特定の気筒で自着火燃焼による燃費向上効果とNOx排出量低減効果を確保することができる。しかも、残りの気筒で空燃比をリッチにして通常点火燃焼を実施することで排気管集合部における排出ガスの空燃比がほぼストイキになるように制御するため、三元触媒等の触媒に流入する排出ガスの空燃比を触媒の浄化ウインド(ストイキ付近)に制御することが可能となり、排出ガス浄化率を向上させることができる。また、特定気筒自着火燃焼モードでは、特定の気筒で自着火燃焼を実施しながら残りの気筒で高出力を実現できる通常点火燃焼を実施するため、全気筒で自着火燃焼を実施する場合に比べて出力トルクを増大させることができる。更に、この出力トルク増大効果により、特定気筒自着火燃焼モードと通常点火燃焼モード(全気筒で通常点火燃焼を実施するモード)との間の出力トルク差を小さくすることができ、燃焼モードを切り換える際のトルク変動を抑制することができる。   In the specific cylinder self-ignition combustion mode, the self-ignition combustion is performed with the air-fuel ratio being lean in the specific cylinder, so that the fuel efficiency improvement effect and the NOx emission reduction effect by the self-ignition combustion can be ensured in the specific cylinder. . In addition, the air-fuel ratio is made rich in the remaining cylinders and normal ignition combustion is performed so that the air-fuel ratio of the exhaust gas in the exhaust pipe collecting portion is controlled to become almost stoichiometric, so that it flows into a catalyst such as a three-way catalyst The air-fuel ratio of the exhaust gas can be controlled to the catalyst purification window (near the stoichiometric range), and the exhaust gas purification rate can be improved. Also, in the specific cylinder auto-ignition combustion mode, normal ignition combustion that can achieve high output in the remaining cylinders while performing auto-ignition combustion in specific cylinders is performed, compared with the case where auto-ignition combustion is performed in all cylinders. Output torque can be increased. Further, the output torque increase effect can reduce the output torque difference between the specific cylinder auto-ignition combustion mode and the normal ignition combustion mode (the mode in which normal ignition combustion is performed in all cylinders), thereby switching the combustion mode. Torque fluctuation at the time can be suppressed.

この場合、請求項2のように、特定気筒自着火燃焼モードで運転しているときに所定期間毎に自着火燃焼を実施する気筒を変更するようにしても良い。このようにすれば、同一の気筒で高温・高圧状態となる自着火燃焼が長期に継続して実施されることを防止でき、自着火燃焼によるダメージを緩和することができると共に、各気筒の温度ばらつきを小さくすることができる。   In this case, as in claim 2, when operating in the specific cylinder self-ignition combustion mode, the cylinder that performs self-ignition combustion may be changed every predetermined period. In this way, it is possible to prevent the self-ignition combustion that becomes a high temperature / high pressure state in the same cylinder from being continuously performed for a long period of time, and it is possible to alleviate the damage caused by the self-ignition combustion and the temperature of each cylinder. Variation can be reduced.

更に、請求項3のように、特定気筒自着火燃焼モードで運転しているときに内燃機関の運転状態に応じて自着火燃焼を実施する気筒数を増減させるようにしても良い。このようにすれば、内燃機関の運転状態に応じて特定気筒自着火燃焼モード運転時の燃費特性や出力トルク特性等を変化させることができる。   Furthermore, as in claim 3, when operating in the specific cylinder self-ignition combustion mode, the number of cylinders that perform auto-ignition combustion may be increased or decreased according to the operating state of the internal combustion engine. In this way, it is possible to change the fuel consumption characteristics, output torque characteristics, etc. during the specific cylinder self-ignition combustion mode operation according to the operating state of the internal combustion engine.

また、請求項4のように、内燃機関の運転状態に応じて、特定気筒自着火燃焼モードと、全気筒で通常点火燃焼を実施する通常点火燃焼モードとを切り換えるようにしても良い。具体的には、請求項5のように、内燃機関の運転状態が所定の低負荷領域のときに通常点火燃焼モードに切り換えるようにすると良い。内燃機関の運転状態が低負荷領域のときには、モータリングの圧縮により得られる熱エネルギが少なくなって自着火燃焼が困難になり、失火しやすくなるため、請求項5のように、内燃機関の運転状態が低負荷領域のときに、通常点火燃焼モードに切り換えれば、全気筒を通常点火燃焼で安定燃焼させることができる。   According to another aspect of the present invention, the specific cylinder self-ignition combustion mode and the normal ignition combustion mode in which normal ignition combustion is performed in all cylinders may be switched according to the operating state of the internal combustion engine. Specifically, as in claim 5, it is preferable to switch to the normal ignition combustion mode when the operating state of the internal combustion engine is in a predetermined low load region. When the operating state of the internal combustion engine is in a low load region, the heat energy obtained by the compression of the motoring is reduced, making it difficult to perform self-ignition combustion and easily misfire. When the state is in the low load region, if the mode is switched to the normal ignition combustion mode, all the cylinders can be stably burned by the normal ignition combustion.

また、請求項6のように、内燃機関の運転状態に応じて、全気筒で自着火燃焼を実施する自着火燃焼モードと、全気筒で通常点火燃焼を実施する通常点火燃焼モードとを切り換えるシステムにおいて、内燃機関の運転状態が所定の低負荷領域のときに通常点火燃焼モードに切り換えるようにしても良い。この場合も、請求項5と同じ効果を得ることができる。   According to another aspect of the present invention, there is provided a system for switching between a self-ignition combustion mode in which self-ignition combustion is performed in all cylinders and a normal ignition combustion mode in which normal ignition combustion is performed in all cylinders in accordance with the operating state of the internal combustion engine. In this case, the normal ignition combustion mode may be switched when the operating state of the internal combustion engine is in a predetermined low load region. In this case, the same effect as that of the fifth aspect can be obtained.

また、請求項7のように、内燃機関の運転状態が所定の高負荷領域のときに通常点火燃焼モードに切り換えるようにしても良い。内燃機関の運転状態が高負荷領域のときには、自着火燃焼によってプレイグニッション(過早点火)が発生しやすくなって、内燃機関がダメージを受けるおそれがあると共に、自着火燃焼では実現困難な高出力が要求されるため、請求項7のように、内燃機関の運転状態が高負荷領域のときに、通常点火燃焼モードに切り換えれば、プレイグニッションを防止して内燃機関がダメージを受けることを未然に防止すると共に、通常点火燃焼により高出力を実現するものである。   Further, as in claim 7, when the operating state of the internal combustion engine is in a predetermined high load region, it may be switched to the normal ignition combustion mode. When the operating state of the internal combustion engine is in a high load range, preignition (pre-ignition) is likely to occur due to self-ignition combustion, which may cause damage to the internal combustion engine, and high output that is difficult to achieve with self-ignition combustion Therefore, when the internal combustion engine is in the high load region as in claim 7, switching to the normal ignition combustion mode prevents preignition and damages the internal combustion engine. In addition, the high output is realized by the normal ignition combustion.

更に、請求項8のように、内燃機関の運転状態が所定の高回転領域のときに通常点火燃焼モードに切り換えるようにしても良い。内燃機関の運転状態が高回転領域のときには、自着火燃焼の着火遅れ期間に対して燃焼サイクルが短くなって、自着火燃焼が困難になり失火しやすくなるため、請求項8のように、内燃機関の運転状態が高回転領域のときに、通常点火燃焼モードに切り換えれば、全気筒を通常点火燃焼で安定燃焼させることができる。   Further, as in the eighth aspect, the normal ignition combustion mode may be switched when the operation state of the internal combustion engine is in a predetermined high rotation region. When the operation state of the internal combustion engine is in the high rotation range, the combustion cycle becomes shorter with respect to the ignition delay period of the self-ignition combustion, so that self-ignition combustion becomes difficult and misfire tends to occur. When the engine operating state is in the high rotation range, switching to the normal ignition combustion mode makes it possible to stably burn all the cylinders with normal ignition combustion.

また、請求項9、10のように、内燃機関の運転状態が所定の中負荷領域のときに特定気筒自着火燃焼モードや自着火燃焼モードに切り換えるようにすると良い。内燃機関の運転状態が中負荷領域のときには、自着火燃焼を安定して実施することができるため、請求項9、10のように、内燃機関の運転状態が中負荷領域のときに、特定気筒自着火燃焼モードや自着火燃焼モードに切り換えれば、自着火燃焼により燃費向上やNOx排出量低減を確実に実現することができる。   Further, as in claims 9 and 10, it is preferable to switch to the specific cylinder self-ignition combustion mode or the self-ignition combustion mode when the operating state of the internal combustion engine is in a predetermined medium load region. When the operating state of the internal combustion engine is in the middle load region, self-ignition combustion can be stably performed. Therefore, as in the ninth and tenth aspects, when the operating state of the internal combustion engine is in the middle load region, the specific cylinder By switching to the self-ignition combustion mode or the self-ignition combustion mode, it is possible to surely improve fuel consumption and reduce NOx emissions by self-ignition combustion.

以下、本発明の一実施例を図面に基づいて説明する。
まず、図1に基づいてエンジン制御システム全体の概略構成を説明する。内燃機関である例えば直列4気筒のエンジン11は、第1気筒#1〜第4気筒#4の4つの気筒を有し、このエンジン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、吸入空気量を検出するエアフローメータ14が設けられている。このエアフローメータ14の下流側には、DCモータ等によって開度調節されるスロットルバルブ15と、スロットル開度を検出するスロットル開度センサ16とが設けられている。
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, a schematic configuration of the entire engine control system will be described with reference to FIG. An in-line four-cylinder engine 11 that is an internal combustion engine, for example, has four cylinders, a first cylinder # 1 to a fourth cylinder # 4, and an air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11. An air flow meter 14 for detecting the intake air amount is provided on the downstream side of the air cleaner 13. On the downstream side of the air flow meter 14, a throttle valve 15 whose opening is adjusted by a DC motor or the like and a throttle opening sensor 16 for detecting the throttle opening are provided.

更に、スロットルバルブ15の下流側には、サージタンク17が設けられ、このサージタンク17には、吸気管圧力を検出する吸気管圧力センサ18が設けられている。また、サージタンク17には、エンジン11の各気筒に空気を導入する吸気マニホールド19が設けられ、各気筒の吸気マニホールド19の吸気ポート近傍に、それぞれ燃料を噴射する燃料噴射弁20が取り付けられている。また、エンジン11のシリンダヘッドには、各気筒毎に点火プラグ21が取り付けられ、各点火プラグ21には、点火装置22で発生した高電圧が印加される。   Further, a surge tank 17 is provided on the downstream side of the throttle valve 15, and an intake pipe pressure sensor 18 for detecting the intake pipe pressure is provided in the surge tank 17. The surge tank 17 is provided with an intake manifold 19 for introducing air into each cylinder of the engine 11, and a fuel injection valve 20 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 19 of each cylinder. Yes. A spark plug 21 is attached to the cylinder head of the engine 11 for each cylinder, and a high voltage generated by the ignition device 22 is applied to each spark plug 21.

一方、エンジン11の各気筒の排気マニホールド23が集合する排気管集合部24には、排出ガス中のCO,HC,NOx等を浄化する三元触媒等の触媒25が設けられ、この触媒25の上流側に、排出ガスの空燃比又はリッチ/リーン等を検出する排出ガスセンサ26(空燃比センサ、酸素センサ等)が設けられている。   On the other hand, a catalyst 25 such as a three-way catalyst for purifying CO, HC, NOx, etc. in the exhaust gas is provided in the exhaust pipe collecting portion 24 where the exhaust manifold 23 of each cylinder of the engine 11 gathers. An exhaust gas sensor 26 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or rich / lean of the exhaust gas is provided on the upstream side.

また、エンジン11のシリンダブロックには、冷却水温を検出する冷却水温センサ27や、エンジン11のクランク軸が所定クランク角回転する毎にパルス信号を出力するクランク角センサ28が取り付けられている。このクランク角センサ28の出力信号に基づいてクランク角やエンジン回転速度が検出される。   A cooling water temperature sensor 27 that detects the cooling water temperature and a crank angle sensor 28 that outputs a pulse signal each time the crankshaft of the engine 11 rotates a predetermined crank angle are attached to the cylinder block of the engine 11. Based on the output signal of the crank angle sensor 28, the crank angle and the engine speed are detected.

これら各種センサの出力は、エンジン制御回路(以下「ECU」と表記する)29に入力される。このECU29は、マイクロコンピュータを主体として構成され、内蔵されたROM(記憶媒体)に記憶された各種のエンジン制御プログラムを実行することで、エンジン運転状態に応じて燃料噴射弁20の燃料噴射量や点火プラグ21の点火時期を制御する。   Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 29. The ECU 29 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium), so that the fuel injection amount of the fuel injection valve 20 can be changed according to the engine operating state. The ignition timing of the spark plug 21 is controlled.

エンジン11は、筒内の混合気に点火プラグ21の火花放電で点火して混合気を火炎伝播燃焼させる通常点火燃焼と、筒内の混合気を圧縮行程で高温・高圧状態にすることで自着火させて燃焼させる自着火燃焼とを実施可能であり、ECU29は、後述する図2乃至図4の各プログラムを実行することで、エンジン運転状態に応じて通常点火燃焼モードと特定気筒自着火燃焼モードとを切り換える(図5参照)。   The engine 11 automatically ignites the air-fuel mixture in the cylinder by spark discharge of the ignition plug 21 and flame-combusts the air-fuel mixture, and sets the air-fuel mixture in the cylinder to a high temperature and high pressure state in the compression stroke. The ECU 29 can execute self-ignition combustion that ignites and combusts, and the ECU 29 executes each program shown in FIGS. 2 to 4 described later, whereby the normal ignition combustion mode and the specific cylinder self-ignition combustion are performed according to the engine operating state. Switch between modes (see FIG. 5).

通常点火燃焼モードでは、全気筒(第1気筒#1〜第4気筒#4)で空燃比A/Fをほぼストイキ(A/F=14.7)にして通常点火燃焼を実施する。一方、特定気筒自着火燃焼モードでは、図6に示すように、特定気筒(例えば4気筒のうちの2気筒)で空燃比A/Fをストイキよりもリーンにして自着火燃焼を実施すると共に残りの気筒で空燃比A/Fをストイキよりもリッチにして通常点火燃焼を実施することで、全気筒の排出ガスが集合する排気管集合部24で排出ガスの平均的な空燃比A/Fがほぼストイキになるように制御する。
以下、ECU29が実行する図2乃至図4に示す各プログラムの処理内容を説明する。
In the normal ignition combustion mode, normal ignition combustion is performed with the air-fuel ratio A / F being substantially stoichiometric (A / F = 14.7) in all cylinders (first cylinder # 1 to fourth cylinder # 4). On the other hand, in the specific cylinder self-ignition combustion mode, as shown in FIG. 6, auto-ignition combustion is performed while the air-fuel ratio A / F is leaner than stoichiometric in a specific cylinder (for example, two of the four cylinders). By performing normal ignition combustion by making the air-fuel ratio A / F richer than stoichiometric in these cylinders, the average air-fuel ratio A / F of the exhaust gas is obtained in the exhaust pipe collecting portion 24 where the exhaust gas of all the cylinders collects. Control to be almost stoichiometric.
Hereinafter, the processing content of each program shown in FIGS. 2 to 4 executed by the ECU 29 will be described.

[燃焼モード切換]
図2に示す燃焼モード切換プログラムは、例えばイグニッションスイッチ(図示せず)のオン後に所定周期で実行される。本プログラムが起動されると、まず、ステップ101〜ステップ103で、特定気筒自着火燃焼モード条件が成立しているか否かを判定する。ここで、特定気筒自着火燃焼モード条件は、例えば、次の(1) 〜(3) の条件を全て満たすことである。
[Combustion mode switching]
The combustion mode switching program shown in FIG. 2 is executed at a predetermined cycle after, for example, an ignition switch (not shown) is turned on. When this program is started, first, in step 101 to step 103, it is determined whether or not the specific cylinder self-ignition combustion mode condition is satisfied. Here, the specific cylinder self-ignition combustion mode condition is, for example, that all the following conditions (1) to (3) are satisfied.

(1) エンジン温度が所定値以上(つまり暖機後)であること(ステップ101)
(2) エンジン負荷(例えば吸気管圧力)が所定領域内であること(ステップ102)
(3) エンジン回転速度が所定領域内であること(ステップ103)
上記(2) と(3) の条件は、図5に示す燃焼モード判定マップを用いて判定される。
(1) The engine temperature is equal to or higher than a predetermined value (that is, after warming up) (step 101).
(2) The engine load (for example, intake pipe pressure) is within a predetermined range (step 102).
(3) The engine speed is within a predetermined range (step 103)
The conditions (2) and (3) are determined using the combustion mode determination map shown in FIG.

一般に、低負荷領域のときには、モータリングの圧縮により得られる熱エネルギが少なくなって、自着火燃焼が困難になり失火しやすくなるため、通常点火燃焼モードに切り換えることが好ましい。また、高負荷領域のときには、自着火燃焼によってプレイグニッション(過早点火)が発生しやすくなって、エンジン11がダメージを受けるおそれがあると共に、自着火燃焼では実現困難な高出力が要求されるため、通常点火燃焼モードに切り換えることが好ましい。更に、高回転領域のときには、自着火燃焼の着火遅れ期間に対して燃焼サイクルが短くなって、自着火燃焼が困難になり失火しやすくなるため、通常点火燃焼モードに切り換えることが好ましい。一方、中負荷領域のときには、自着火燃焼を安定して実施することができるため、特定気筒自着火燃焼モードに切り換えることが好ましい。   In general, in the low load region, it is preferable to switch to the normal ignition combustion mode because the thermal energy obtained by the compression of the motoring is reduced and the self-ignition combustion becomes difficult and misfires easily occur. Further, in the high load region, pre-ignition (pre-ignition) is likely to occur due to self-ignition combustion, the engine 11 may be damaged, and a high output that is difficult to achieve with self-ignition combustion is required. Therefore, it is preferable to switch to the normal ignition combustion mode. Further, in the high rotation range, the combustion cycle becomes shorter with respect to the ignition delay period of the self-ignition combustion, and the self-ignition combustion becomes difficult and misfires easily. Therefore, it is preferable to switch to the normal ignition combustion mode. On the other hand, since the self-ignition combustion can be stably performed in the middle load region, it is preferable to switch to the specific cylinder self-ignition combustion mode.

これらの事情を考慮して、図5に示す燃焼モード判定マップは、中負荷且つ低中回転領域(但しアイドル回転及びその近傍の領域は除く)では、特定気筒自着火燃焼モードが選択され、一方、低負荷領域と高負荷領域、高回転領域とアイドル回転及びその近傍の領域では、通常点火燃焼モードが選択されるように設定されている。   In consideration of these circumstances, in the combustion mode determination map shown in FIG. 5, the specific cylinder self-ignition combustion mode is selected in the medium load and low / medium rotation region (except for the idle rotation and the region in the vicinity thereof). The normal ignition combustion mode is set to be selected in the low load region and high load region, in the high rotation region and idle rotation, and in the vicinity thereof.

上記(1) 〜(3) の条件を全て満たせば、特定気筒自着火燃焼モード条件が成立するが、上記(1) 〜(3) の条件のうち1つでも満たさない条件があれば、特定気筒自着火燃焼モード条件が不成立となる。   If all of the above conditions (1) to (3) are satisfied, the specific cylinder self-ignition combustion mode condition is satisfied. If any of the above conditions (1) to (3) does not satisfy the condition, The cylinder auto-ignition combustion mode condition is not satisfied.

その結果、特定気筒自着火燃焼モード条件が成立していると判定された場合には、ステップ104に進み、後述する図3の特定気筒自着火燃焼制御プログラムを実行して、特定気筒で空燃比A/Fをリーンにして自着火燃焼を実施すると共に残りの気筒で空燃比A/Fをリッチにして通常点火燃焼を実施することで、排気管集合部24における排出ガスの平均的な空燃比A/Fがほぼストイキになるように制御する。   As a result, if it is determined that the specific cylinder self-ignition combustion mode condition is satisfied, the routine proceeds to step 104, where a specific cylinder self-ignition combustion control program of FIG. By performing auto-ignition combustion with lean A / F and performing normal ignition combustion with rich air-fuel ratio A / F in the remaining cylinders, the average air-fuel ratio of the exhaust gas in the exhaust pipe assembly 24 A / F is controlled to be almost stoichiometric.

一方、上記ステップ101〜103で、特定気筒自着火燃焼モード条件が不成立と判定された場合には、ステップ105に進み、図示しない通常点火燃焼制御プログラムを実行して、全気筒で空燃比をほぼストイキにして通常点火燃焼を実施する。このステップ105の処理が特許請求の範囲でいう通常点火燃焼制御手段としての役割果たす。   On the other hand, if it is determined in steps 101 to 103 that the specific cylinder self-ignition combustion mode condition is not satisfied, the routine proceeds to step 105, where a normal ignition combustion control program (not shown) is executed, and the air-fuel ratio is substantially reduced in all cylinders. Use normal ignition combustion as a stoichiometric. The process of step 105 serves as a normal ignition combustion control means in the claims.

[特定気筒自着火燃焼制御]
図2のステップ104で実行される図3の特定気筒自着火燃焼制御プログラムは、特許請求の範囲でいう特定気筒自着火制御手段としての役割を果たす。本プログラムが起動されると、まず、ステップ201で、図6に示すように、特定気筒(例えば4気筒のうちの2気筒)の空燃比をストイキよりもリーン(例えばA/F=22〜25)にするように燃料供給量を設定し、残りの気筒の空燃比をストイキよりもリッチにするように燃料供給量を設定して、全気筒の排出ガスが集合する排気管集合部24で排出ガスの平均的な空燃比A/Fがほぼストイキになるように制御する。
[Specific cylinder self-ignition combustion control]
The specific cylinder self-ignition combustion control program of FIG. 3 executed in step 104 of FIG. 2 serves as specific cylinder self-ignition control means in the claims. When this program is started, first, at step 201, as shown in FIG. 6, the air-fuel ratio of a specific cylinder (for example, 2 of 4 cylinders) is leaner than stoichiometric (for example, A / F = 22 to 25). ), The fuel supply amount is set so that the air-fuel ratio of the remaining cylinders is richer than the stoichiometric ratio, and exhaust is performed at the exhaust pipe collecting portion 24 where exhaust gases of all the cylinders collect. Control is performed so that the average air-fuel ratio A / F of the gas becomes almost stoichiometric.

この場合、図7に示すように、特定気筒(リーンにする気筒)と残りの気筒(リッチにする気筒)は、燃焼順に交互になるように設定する。また、図8に示すように、通常点火燃焼モードから特定気筒自着火燃焼モードに切り換える際には、特定気筒は、空燃比A/Fをストイキから徐々にリーンに変化させ、残りの気筒は、空燃比A/Fをストイキから徐々にリッチに変化させるように制御する。一方、特定気筒自着火燃焼モードから通常点火燃焼モードに切り換える際には、特定気筒は、空燃比A/Fをリーンから徐々にストイキに変化させ、残りの気筒は、空燃比A/Fをリッチから徐々にストイキに変化させるように制御する。   In this case, as shown in FIG. 7, the specific cylinder (the lean cylinder) and the remaining cylinders (the rich cylinder) are set to alternate in the combustion order. Further, as shown in FIG. 8, when switching from the normal ignition combustion mode to the specific cylinder self-ignition combustion mode, the specific cylinder gradually changes the air-fuel ratio A / F from stoichiometric to lean, and the remaining cylinders The air-fuel ratio A / F is controlled so as to gradually change from stoichiometric to rich. On the other hand, when switching from the specific cylinder self-ignition combustion mode to the normal ignition combustion mode, the specific cylinder gradually changes the air-fuel ratio A / F from lean to stoichiometric, and the remaining cylinders enrich the air-fuel ratio A / F. Control to gradually change from stoichiometric to stoichiometric.

この後、ステップ202に進み、後述する図4の点火制御プログラムを実行して、特定気筒で自着火燃焼を実施する。尚、残りの気筒では通常点火燃焼を実施する。
この後、ステップ203に進み、今回の特定気筒での自着火燃焼の継続時間をカウントする自着火燃焼継続カウンタをカウントアップした後、ステップ204に進み、自着火燃焼継続カウンタのカウント値が所定値T以上であるか否かによって、今回の特定気筒での自着火燃焼の継続期間が所定期間T以上になったか否かを判定する。尚、所定期間Tは、時間で設定しても良いが、クランク角や燃焼サイクル数等で設定しても良い。
Thereafter, the routine proceeds to step 202, where an ignition control program shown in FIG. 4 to be described later is executed to perform self-ignition combustion in the specific cylinder. In the remaining cylinders, normal ignition combustion is performed.
Thereafter, the process proceeds to step 203, and after counting up the self-ignition combustion continuation counter that counts the duration of the self-ignition combustion in the specific cylinder this time, the process proceeds to step 204 and the count value of the self-ignition combustion continuation counter is a predetermined value. It is determined whether or not the duration of the self-ignition combustion in the specific cylinder has become a predetermined period T or more depending on whether or not it is T or more. The predetermined period T may be set by time, but may be set by a crank angle, the number of combustion cycles, or the like.

その結果、今回の特定気筒での自着火燃焼の継続期間が所定期間Tに達していないと判定されれば、今回の特定気筒で自着火燃焼を実施したまま、本プログラムを終了する。   As a result, if it is determined that the duration of the self-ignition combustion in the current specific cylinder has not reached the predetermined period T, the program is terminated while the self-ignition combustion is being performed in the current specific cylinder.

その後、上記ステップ204で、今回の特定気筒での自着火燃焼の継続期間が所定期間T以上になったと判定され時点で、ステップ205に進み、特定気筒(つまり自着火燃焼を実施する気筒)を変更する。例えば、図7に示すように、それまで特定気筒が第1気筒#1と第4気筒#4の場合には、特定気筒を第3気筒#3と第2気筒#2に変更する。これにより、所定期間T毎に特定気筒(つまり自着火燃焼を実施する気筒)を変更する。   Thereafter, in step 204, when it is determined that the duration of the self-ignition combustion in the current specific cylinder is equal to or longer than the predetermined period T, the process proceeds to step 205, and the specific cylinder (that is, the cylinder that performs self-ignition combustion) is selected. change. For example, as shown in FIG. 7, when the specific cylinders are the first cylinder # 1 and the fourth cylinder # 4 so far, the specific cylinders are changed to the third cylinder # 3 and the second cylinder # 2. As a result, the specific cylinder (that is, the cylinder that performs self-ignition combustion) is changed every predetermined period T.

[点火制御]
図3のステップ202で実行される図4の点火制御プログラムは、特定気筒の点火制御を行って特定気筒の自着火燃焼を制御するものであり、特定気筒で混合気を自着火させる際に、点火プラグ21を複数回点火する多重点火を実行して、自着火を活性化させるための補助エネルギを複数回付与することで、自着火可能な運転領域を拡大すると共に、自着火燃焼を安定化させるようにしている。
[Ignition control]
The ignition control program of FIG. 4 executed in step 202 of FIG. 3 performs ignition control of a specific cylinder to control self-ignition combustion of the specific cylinder. When the air-fuel mixture is self-ignited in the specific cylinder, By performing multiple ignition for igniting the spark plug 21 a plurality of times and providing auxiliary energy for activating self-ignition a plurality of times, the operation range where self-ignition can be performed is expanded and self-ignition combustion is stabilized. I try to make it.

本プログラムが起動されると、まず、ステップ301で、空燃比A/Fとエンジン運転状態(例えばエンジン負荷、エンジン回転速度、冷却水温等のうちの少なくとも1つ)とに応じた着火遅れ期間τi (i=1〜3)をマップ又は数式等により算出する。ここで、τ1 は自着火条件成立直後の冷炎が発現する前の期間、τ2 は冷炎が発現する期間、τ3 は青炎が発現する期間である。   When this program is started, first, in step 301, the ignition delay period τi according to the air-fuel ratio A / F and the engine operating state (for example, at least one of engine load, engine speed, coolant temperature, etc.). (i = 1 to 3) is calculated by a map or a mathematical expression. Here, τ1 is a period before the cold flame immediately after the self-ignition condition is established, τ2 is a period when the cold flame is developed, and τ3 is a period when the blue flame is developed.

着火遅れ期間τi のマップは、予め、理論式、設計データ、実験データ等に基づいて設定され、ECU29のROMに記憶されている。尚、着火遅れ期間τi の算出に用いる理論式として、下記の「アレニウスの式」を用いると良い。
τi =ai ×Pbi×exp(ci /T)
ここで、Pは圧力、Tは温度、ai,bi,ci は空燃比A/F等に応じた係数である。
The map of the ignition delay period τi is set in advance based on theoretical formulas, design data, experimental data, etc., and is stored in the ROM of the ECU 29. The following “Arrhenius equation” may be used as a theoretical equation for calculating the ignition delay period τi.
τi = ai × P bi × exp (ci / T)
Here, P is a pressure, T is a temperature, and a i, b i, and c i are coefficients corresponding to the air-fuel ratio A / F and the like.

着火遅れ期間τi の算出後、ステップ302に進み、着火遅れ期間τ(=τ1 +τ2 +τ3 )に基づいて冷炎発現に必要な点火時期とエネルギ量E1 を算出した後、ステップ303に進み、冷炎発現用の1回目の点火時期を決定する。この冷炎発現用の1回目の点火時期は、従来のプレ点火時期(例えばBTDC50℃A付近)よりも遅角した点火時期(例えばBTDC30℃A付近)に設定される。   After calculating the ignition delay period τi, the process proceeds to step 302. After calculating the ignition timing and energy amount E1 required for the cold flame based on the ignition delay period τ (= τ1 + τ2 + τ3), the process proceeds to step 303, where The first ignition timing for expression is determined. The first ignition timing for developing the cold flame is set to an ignition timing (for example, near BTDC 30 ° C. A) that is retarded from the conventional pre-ignition timing (for example, near BTDC 50 ° C. A).

この冷炎発現用の1回目の点火時期(1回目の補助エネルギの付与時期)によって自着火条件の成立時期、つまり、着火遅れ期間τの開始時期が変化するため、冷炎発現用の1回目の点火時期を調整することで、着火遅れ期間τの開始時期を調整して、着火遅れ期間τの終了時期、つまり、自着火の開始時期を調整することができる。   Since the timing of establishment of the auto-ignition condition, that is, the start timing of the ignition delay period τ, changes depending on the first ignition timing for the cold flame expression (first auxiliary energy application timing). By adjusting the ignition timing, the start timing of the ignition delay period τ can be adjusted, and the end timing of the ignition delay period τ, that is, the start timing of self-ignition can be adjusted.

この後、ステップ304に進み、冷炎発現に必要なエネルギ量E1 が1回の点火で付与可能な最大補助エネルギ量Emax 以上であるか否かを判定する。この最大補助エネルギ量Emax は、点火装置22(イグニッションコイル等)や点火プラグ21の性能によって決まる値である。   Thereafter, the routine proceeds to step 304, where it is determined whether or not the energy amount E1 required for the onset of the cold flame is equal to or greater than the maximum auxiliary energy amount Emax that can be applied by one ignition. This maximum auxiliary energy amount Emax is a value determined by the performance of the ignition device 22 (ignition coil or the like) and the ignition plug 21.

その結果、冷炎発現に必要なエネルギ量E1 が最大補助エネルギ量Emax 以上であると判定された場合には、冷炎発現に必要な残りのエネルギ量(E1 −Emax )を2回目以降の点火で付与する必要があると判断して、ステップ305に進み、冷炎発現用の2回目以降の点火回数と点火時期と各点火で付与する補助エネルギ量を算出して決定する。   As a result, if it is determined that the amount of energy E1 required for the onset of the cold flame is greater than or equal to the maximum auxiliary energy amount Emax, the remaining amount of energy (E1 -Emax) required for the onset of the cool flame is used for the second and subsequent ignitions. In step 305, the process proceeds to step 305, where the number of ignitions for the second and subsequent times for generating a cold flame, the ignition timing, and the amount of auxiliary energy applied in each ignition are calculated and determined.

一方、上記ステップ304で、冷炎発現に必要なエネルギ量E1 が最大補助エネルギ量Emax よりも小さいと判定された場合には、冷炎発現に必要なエネルギ量E1 を1回目の点火で付与することができると判断して、ステップ305の処理を飛ばしてステップ306に進む。   On the other hand, if it is determined in step 304 that the energy amount E1 required for the cold flame expression is smaller than the maximum auxiliary energy amount Emax, the energy amount E1 required for the cold flame expression is applied by the first ignition. If it can be determined, the process of step 305 is skipped and the process proceeds to step 306.

このステップ306では、着火遅れ期間(τ2 +τ3 )に基づいて青炎発現に必要な点火時期とエネルギ量E2 を算出した後、ステップ307に進み、青炎発現用の1回目の点火時期を決定する。この青炎発現用の1回目の点火時期は、着火遅れ期間τの吸熱反応に相当する時期又はその直前に設定される。   In this step 306, after calculating the ignition timing and energy amount E2 necessary for the blue flame development based on the ignition delay period (τ2 + τ3), the process proceeds to step 307 to determine the first ignition timing for the blue flame development. . The first ignition timing for developing blue flame is set at or just before the timing corresponding to the endothermic reaction in the ignition delay period τ.

この後、ステップ308に進み、青炎発現に必要なエネルギ量E2 が1回の点火で付与可能な最大補助エネルギ量Emax 以上であるか否かを判定する。
その結果、青炎発現に必要なエネルギ量E2 が最大補助エネルギ量Emax 以上であると判定された場合には、青炎発現に必要な残りのエネルギ量(E2 −Emax )を2回目以降の点火で付与する必要があると判断して、ステップ309に進み、青炎発現用の2回目以降の点火回数と点火時期と各点火で付与する補助エネルギ量を算出して決定する。この青炎発現用の2回目以降の点火時期は、着火遅れ期間τの吸熱反応に相当する時期又はその直前に設定される。
Thereafter, the routine proceeds to step 308, where it is determined whether or not the energy amount E2 required for the blue flame is equal to or greater than the maximum auxiliary energy amount Emax that can be applied by one ignition.
As a result, if it is determined that the amount of energy E2 required for the onset of blue flame is greater than or equal to the maximum auxiliary energy amount Emax, the remaining amount of energy (E2 -Emax) required for the onset of blue flame is ignited for the second and subsequent times. In step 309, the number of times of ignition for the second and subsequent times, the ignition timing, and the amount of auxiliary energy applied in each ignition are calculated and determined. The second and subsequent ignition timings for developing blue flame are set at or just before the timing corresponding to the endothermic reaction in the ignition delay period τ.

着火遅れ期間τのばらつきが大きいと、自着火の開始時期の制御精度が低下するが、この青炎発現用の1回目及び2回目以降の点火時期(補助エネルギの付与時期)を着火遅れ期間τの吸熱反応に相当する時期又はその直前に制御することで、吸熱反応を促進して吸熱反応のばらつきを抑制することができて、着火遅れ期間τのばらつきを抑制することができ、自着火の開始時期の制御精度を向上させることができる。   If the variation of the ignition delay period τ is large, the control accuracy of the start timing of the self-ignition is lowered. However, the ignition timings for applying the first and second times (applying timing of auxiliary energy) for the blue flame expression are set to the ignition delay period τ. By controlling the timing corresponding to or immediately before the endothermic reaction, it is possible to promote the endothermic reaction and suppress the variation in the endothermic reaction, to suppress the variation in the ignition delay period τ, The control accuracy of the start time can be improved.

一方、上記ステップ308で、青炎発現に必要なエネルギ量E2 が最大補助エネルギ量Emax よりも小さいと判定された場合には、青炎発現に必要なエネルギ量E2 を1回目の点火で付与することができると判断して、ステップ309の処理を飛ばして本プログラムを終了する。   On the other hand, if it is determined in step 308 that the amount of energy E2 required for developing blue flame is smaller than the maximum auxiliary energy amount Emax, the amount of energy E2 required for developing blue flame is applied by the first ignition. If it can be determined, the process of step 309 is skipped and the program is terminated.

以上説明した本実施例によれば、エンジン運転状態に応じて通常点火燃焼モードと特定気筒自着火燃焼モードとを切り換え、特定気筒自着火燃焼モードでは、図6に示すように、特定気筒(例えば4気筒のうちの2気筒)で空燃比A/Fをリーンにして自着火燃焼を実施すると共に残りの気筒で空燃比A/Fをリッチにして通常点火燃焼を実施することで、全気筒の排出ガスが集合する排気管集合部24で排出ガスの平均的な空燃比A/Fがほぼストイキになるように制御する。   According to the present embodiment described above, the normal ignition combustion mode and the specific cylinder self-ignition combustion mode are switched according to the engine operating state. In the specific cylinder self-ignition combustion mode, as shown in FIG. Auto-ignition combustion is performed with the air-fuel ratio A / F being lean in two cylinders of the four cylinders), and normal ignition combustion is performed with the remaining air-fuel ratio A / F being rich in the remaining cylinders. Control is performed so that the average air-fuel ratio A / F of the exhaust gas becomes substantially stoichiometric in the exhaust pipe collecting portion 24 where the exhaust gas collects.

この特定気筒自着火燃焼モードでは、特定気筒で空燃比A/Fをリーンにして自着火燃焼を実施するため、特定気筒では自着火燃焼による燃費向上効果とNOx排出量低減効果を確保することができる。しかも、残りの気筒で空燃比A/Fをリッチにして通常点火燃焼を実施することで排気管集合部24で排出ガスの空燃比A/Fがほぼストイキになるように制御するため、三元触媒等の触媒25に流入する排出ガスの空燃比A/Fを触媒25の浄化ウインド(ストイキ付近)に制御することが可能となり、排出ガス浄化率を向上させることができる。また、特定気筒自着火燃焼モードでは、特定気筒で自着火燃焼を実施しながら残りの気筒で高出力を実現できる通常点火燃焼を実施するため、全気筒で自着火燃焼を実施する場合に比べて出力トルクを増大させることができる。更に、この出力トルク増大効果により、特定気筒自着火燃焼モードと通常点火燃焼モードとの間の出力トルク差を小さくすることができ、特定気筒自着火燃焼モードと通常点火燃焼モードとの間で燃焼モードを切り換える際のトルク変動を抑制することができる。   In this specific cylinder self-ignition combustion mode, since the specific cylinder performs auto-ignition combustion with the air-fuel ratio A / F being lean, it is possible to ensure the fuel efficiency improvement effect and the NOx emission reduction effect by the self-ignition combustion in the specific cylinder. it can. In addition, since the air-fuel ratio A / F is made rich in the remaining cylinders and the normal ignition combustion is performed, the exhaust pipe collecting portion 24 controls the air-fuel ratio A / F of the exhaust gas to be almost stoichiometric. The air-fuel ratio A / F of the exhaust gas flowing into the catalyst 25 such as the catalyst can be controlled to the purification window (near the stoichiometric) of the catalyst 25, and the exhaust gas purification rate can be improved. Also, in the specific cylinder self-ignition combustion mode, normal ignition combustion that can achieve high output in the remaining cylinders while performing self-ignition combustion in the specific cylinders is performed, so compared with the case of performing self-ignition combustion in all the cylinders. The output torque can be increased. Further, the output torque increase effect can reduce the output torque difference between the specific cylinder self-ignition combustion mode and the normal ignition combustion mode, and combustion between the specific cylinder self-ignition combustion mode and the normal ignition combustion mode can be achieved. Torque fluctuations when switching modes can be suppressed.

また、本実施例では、特定気筒自着火燃焼モードで運転しているときに所定期間T毎に特定気筒、つまり、自着火燃焼を実施する気筒を変更するようにしたので、同一の気筒で高温・高圧状態となる自着火燃焼が長期に継続して実施されることを防止でき、自着火燃焼によるダメージを緩和することができると共に、各気筒の温度ばらつきを小さくすることができる。   In this embodiment, the specific cylinder, that is, the cylinder that performs the auto-ignition combustion is changed every predetermined period T when operating in the specific cylinder auto-ignition combustion mode. -It is possible to prevent the self-ignition combustion that becomes a high pressure state from being continuously performed for a long period of time, to reduce damage caused by the self-ignition combustion, and to reduce the temperature variation of each cylinder.

しかしながら、特定気筒自着火燃焼モードで運転しているときに自着火燃焼を実施する気筒を同一の気筒に固定して、制御を簡略化するようにしても良い。
また、特定気筒自着火燃焼モードで運転しているときにエンジン運転状態に応じて自着火燃焼を実施する気筒数を増減させるようにしても良い。このようにすれば、エンジン運転状態に応じて特定気筒自着火燃焼モード運転時の燃費特性や出力トルク特性等を変化させることができる。
However, the control may be simplified by fixing the cylinder that performs the self-ignition combustion to the same cylinder when operating in the specific cylinder self-ignition combustion mode.
In addition, when operating in the specific cylinder self-ignition combustion mode, the number of cylinders that perform self-ignition combustion may be increased or decreased according to the engine operating state. In this way, fuel consumption characteristics, output torque characteristics, and the like during specific cylinder self-ignition combustion mode operation can be changed according to the engine operating state.

また、本実施例では、低負荷領域のときには、モータリングの圧縮により得られる熱エネルギが少なくなって自着火燃焼が困難になり失火しやすくなることを考慮して、通常点火燃焼モードに切り換えるようにしたので、低負荷領域のときに、全気筒を通常点火燃焼で安定して運転することができる。   Further, in this embodiment, in the low load region, considering that the thermal energy obtained by compression of the motoring is small and the self-ignition combustion becomes difficult and the misfire is likely to occur, the mode is switched to the normal ignition combustion mode. Therefore, all the cylinders can be stably operated by the normal ignition combustion in the low load region.

更に、本実施例では、高負荷領域のときには、自着火燃焼によりプレイグニッション(過早点火)が発生しやすくなってエンジン11がダメージを受けるおそれがあると共に、自着火燃焼では実現困難な高出力が要求されることを考慮して、通常点火燃焼モードに切り換えるようにしたので、高負荷領域のときに、プレイグニッションを防止してエンジン11がダメージを受けることを未然に防止できると共に、通常点火燃焼により高出力を実現することができる。   Further, in the present embodiment, in the high load region, pre-ignition (pre-ignition) is likely to occur due to self-ignition combustion, and the engine 11 may be damaged, and high output that is difficult to realize with self-ignition combustion. In view of the fact that the engine 11 is required to switch to the normal ignition combustion mode, pre-ignition can be prevented in the high load region to prevent the engine 11 from being damaged, and the normal ignition can be performed. High output can be achieved by combustion.

また、本実施例では、高回転領域のときには、自着火燃焼の着火遅れ期間に対して燃焼サイクルが短くなって自着火燃焼が困難になり失火しやすくなることを考慮して、通常点火燃焼モードに切り換えるようにしたので、高回転領域のときに、全気筒を通常点火燃焼で安定して運転することができる。   Further, in this embodiment, in the high speed region, the normal ignition combustion mode is considered in consideration of the fact that the combustion cycle becomes short with respect to the ignition delay period of the self-ignition combustion, and that the self-ignition combustion becomes difficult and misfires easily occur. Therefore, all cylinders can be stably operated by normal ignition combustion in the high rotation range.

また、本実施例では、中負荷領域のときには、自着火燃焼を安定して実施することができることを考慮して、特定気筒自着火燃焼モードに切り換えるようにしたので、中負荷領域のときに、自着火燃焼により燃費向上やNOx排出量低減を確実に実現することができる。   In the present embodiment, in the middle load region, considering that the self-ignition combustion can be stably performed, the mode is switched to the specific cylinder self-ignition combustion mode. The self-ignition combustion can surely improve fuel consumption and reduce NOx emissions.

尚、全気筒で自着火燃焼を実施する自着火燃焼モードと、全気筒で通常点火燃焼を実施する通常点火燃焼モードとを切り換えるシステムにおいて、低負荷領域と高負荷領域及び高回転領域のときに通常点火燃焼モードに切り換え、中負荷領域のときに自着火燃焼モードに切り換えるようにしても良い。   In a system that switches between a self-ignition combustion mode in which self-ignition combustion is performed in all cylinders and a normal ignition combustion mode in which normal ignition combustion is performed in all cylinders, in a low load region, a high load region, and a high rotation region. It is possible to switch to the normal ignition combustion mode and switch to the self-ignition combustion mode in the middle load region.

また、上記実施例では、混合気を自着火させる際に、多重点火を行うようにしたが、混合気を自着火させる際に、1回だけ点火するか又は点火を行わないようにしても良い。
その他、本発明は、4気筒エンジンに限定されず、3気筒以下又は5気筒以上の多気筒エンジンに適用しても良く、また、直列エンジンに限定されず、V型エンジンや水平対向エンジン等、様々な型式のエンジンに適用することができ、更には、吸気ポート噴射式のエンジンに限定されず、筒内噴射式のエンジンにも適用できる等、種々変更して実施できる。
In the above embodiment, multiple ignition is performed when the air-fuel mixture is self-ignited. However, when the air-fuel mixture is self-ignited, only one ignition or no ignition is performed. good.
In addition, the present invention is not limited to a four-cylinder engine and may be applied to a multi-cylinder engine having three or less cylinders or five or more cylinders, and is not limited to an in-line engine, such as a V-type engine or a horizontally opposed engine, The present invention can be applied to various types of engines, and is not limited to an intake port injection type engine, and can be implemented with various modifications such as being applicable to an in-cylinder injection type engine.

本発明の一実施例におけるエンジン制御システム全体の概略構成図である。It is a schematic block diagram of the whole engine control system in one Example of this invention. 燃焼モード切換プログラムの処理の流れを示すフローチャートである。It is a flowchart which shows the flow of a process of a combustion mode switching program. 特定気筒自着火燃焼制御プログラムの処理の流れを示すフローチャートである。It is a flowchart which shows the flow of a process of a specific cylinder self-ignition combustion control program. 点火制御プログラムの処理の流れを示すフローチャートである。It is a flowchart which shows the flow of a process of an ignition control program. 燃焼モード判定マップの一例を概念的に示す図である。It is a figure which shows notionally an example of a combustion mode determination map. 特定気筒自着火燃焼モードを説明するためのエンジン及び排気系の平面図である。It is a top view of an engine and an exhaust system for explaining a specific cylinder self-ignition combustion mode. 特定気筒自着火燃焼モードの空燃比制御を説明するためのタイムチャートである。6 is a time chart for explaining air-fuel ratio control in a specific cylinder self-ignition combustion mode. 燃焼モード切換時の空燃比制御を説明するためのタイムチャートである。It is a time chart for demonstrating the air fuel ratio control at the time of combustion mode switching.

符号の説明Explanation of symbols

11…エンジン(内燃機関)、12…吸気管、15…スロットルバルブ、20…燃料噴射弁、21…点火プラグ、24…排気管集合部、25…触媒、29…ECU(特定気筒自着火燃焼制御手段,通常点火燃焼制御手段,燃焼モード切換手段,自着火燃焼制御手段)   DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 15 ... Throttle valve, 20 ... Fuel injection valve, 21 ... Spark plug, 24 ... Exhaust pipe collection part, 25 ... Catalyst, 29 ... ECU (specific cylinder self-ignition combustion control) Means, normal ignition combustion control means, combustion mode switching means, self-ignition combustion control means)

Claims (10)

筒内の混合気を圧縮により自着火させて燃焼させる自着火燃焼と、筒内の混合気を点火手段で点火して火炎伝播燃焼させる通常点火燃焼とを切り換えて運転する内燃機関の制御装置において、
特定の気筒で空燃比をストイキよりもリーンにして前記自着火燃焼を実施すると共に残りの気筒で空燃比をストイキよりもリッチにして前記通常点火燃焼を実施する特定気筒自着火燃焼モードで運転することで、排気管集合部における排出ガスの空燃比がほぼストイキになるように制御する特定気筒自着火燃焼制御手段を備えていることを特徴とする内燃機関の制御装置。
In a control apparatus for an internal combustion engine that operates by switching between self-ignition combustion in which an air-fuel mixture in a cylinder is self-ignited by compression and combustion and normal ignition combustion in which the air-fuel mixture in the cylinder is ignited by ignition means and flame propagation combustion is performed. ,
A specific cylinder is operated in a specific cylinder self-ignition combustion mode in which the air-fuel ratio is leaner than stoichiometric and the self-ignition combustion is performed and the remaining cylinders are richer than stoichiometric and the normal ignition combustion is performed. Thus, a control apparatus for an internal combustion engine is provided with specific cylinder self-ignition combustion control means for controlling the air-fuel ratio of the exhaust gas in the exhaust pipe collecting portion to become substantially stoichiometric.
前記特定気筒自着火燃焼制御手段は、前記特定気筒自着火燃焼モードで運転しているときに所定期間毎に前記自着火燃焼を実施する気筒を変更することを特徴とする請求項1に記載の内燃機関の制御装置。   The said specific cylinder self-ignition combustion control means changes the cylinder which implements the said self-ignition combustion for every predetermined period, when operating in the said specific cylinder self-ignition combustion mode. Control device for internal combustion engine. 前記特定気筒自着火燃焼制御手段は、前記特定気筒自着火燃焼モードで運転しているときに内燃機関の運転状態に応じて前記自着火燃焼を実施する気筒数を増減させることを特徴とする請求項1又は2に記載の内燃機関の制御装置。   The specific cylinder self-ignition combustion control means increases or decreases the number of cylinders that perform the self-ignition combustion according to an operating state of an internal combustion engine when operating in the specific cylinder self-ignition combustion mode. Item 3. The control device for an internal combustion engine according to Item 1 or 2. 全気筒で前記通常点火燃焼を実施する通常点火燃焼モードで運転するように制御する通常点火燃焼制御手段と、
内燃機関の運転状態に応じて前記特定気筒自着火燃焼モードと前記通常点火燃焼モードとを切り換える燃焼モード切換手段とを備えてい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の制御装置。
Normal ignition combustion control means for controlling to operate in a normal ignition combustion mode for performing the normal ignition combustion in all cylinders;
The internal combustion engine according to any one of claims 1 to 3, further comprising combustion mode switching means for switching between the specific cylinder self-ignition combustion mode and the normal ignition combustion mode in accordance with an operating state of the internal combustion engine. Engine control device.
前記燃焼モード切換手段は、内燃機関の運転状態が所定の低負荷領域のときに前記通常点火燃焼モードに切り換えることを特徴とする請求項4に記載の内燃機関の制御装置。   5. The control apparatus for an internal combustion engine according to claim 4, wherein the combustion mode switching means switches to the normal ignition combustion mode when the operating state of the internal combustion engine is in a predetermined low load region. 筒内の混合気を圧縮により自着火させて燃焼させる自着火燃焼と、筒内の混合気を点火手段で点火して火炎伝播燃焼させる通常点火燃焼とを切り換えて運転する内燃機関の制御装置において、
全気筒で前記自着火燃焼を実施する自着火燃焼モードで運転するように制御する自着火燃焼制御手段と、
全気筒で前記通常点火燃焼を実施する通常点火燃焼モードで運転するように制御する通常点火燃焼制御手段と、
内燃機関の運転状態に応じて前記自着火燃焼モードと前記通常点火燃焼モードとを切り換える燃焼モード切換手段とを備え、
前記燃焼モード切換手段は、内燃機関の運転状態が所定の低負荷領域のときに前記通常点火燃焼モードに切り換えることを特徴とする内燃機関の制御装置。
In a control apparatus for an internal combustion engine that operates by switching between self-ignition combustion in which an air-fuel mixture in a cylinder is self-ignited by compression and combustion and normal ignition combustion in which the air-fuel mixture in the cylinder is ignited by ignition means and flame propagation combustion is performed. ,
Self-ignition combustion control means for controlling to operate in a self-ignition combustion mode in which the self-ignition combustion is performed in all cylinders;
Normal ignition combustion control means for controlling to operate in a normal ignition combustion mode for performing the normal ignition combustion in all cylinders;
Combustion mode switching means for switching between the self-ignition combustion mode and the normal ignition combustion mode according to the operating state of the internal combustion engine,
The control device for an internal combustion engine, wherein the combustion mode switching means switches to the normal ignition combustion mode when the operating state of the internal combustion engine is in a predetermined low load region.
前記燃焼モード切換手段は、内燃機関の運転状態が所定の高負荷領域のときに前記通常点火燃焼モードに切り換えることを特徴とする請求項4乃至6のいずれかに記載の内燃機関の制御装置。   The control apparatus for an internal combustion engine according to any one of claims 4 to 6, wherein the combustion mode switching means switches to the normal ignition combustion mode when the operating state of the internal combustion engine is in a predetermined high load region. 前記燃焼モード切換手段は、内燃機関の運転状態が所定の高回転領域のときに前記通常点火燃焼モードに切り換えることを特徴とする請求項4乃至7のいずれかに記載の内燃機関の制御装置。   The internal combustion engine control device according to any one of claims 4 to 7, wherein the combustion mode switching means switches to the normal ignition combustion mode when the operating state of the internal combustion engine is in a predetermined high rotation range. 前記燃焼モード切換手段は、内燃機関の運転状態が所定の中負荷領域のときに前記特定気筒自着火燃焼モードに切り換えることを特徴とする請求項4又は5に記載の内燃機関の制御装置。   6. The control apparatus for an internal combustion engine according to claim 4, wherein the combustion mode switching means switches to the specific cylinder self-ignition combustion mode when the operating state of the internal combustion engine is in a predetermined medium load region. 前記燃焼モード切換手段は、内燃機関の運転状態が所定の中負荷領域のときに前記自着火燃焼モードに切り換えることを特徴とする請求項6に記載の内燃機関の制御装置。   The control device for an internal combustion engine according to claim 6, wherein the combustion mode switching means switches to the self-ignition combustion mode when the operating state of the internal combustion engine is in a predetermined medium load region.
JP2004180546A 2004-06-18 2004-06-18 Control device for internal combustion engine Pending JP2006002683A (en)

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JP2008144765A (en) * 2006-12-08 2008-06-26 Ford Global Technologies Llc Method and system for controlling engine provided with cylinders using electronic valve actuation
JP2008274954A (en) * 2007-05-07 2008-11-13 Ford Global Technologies Llc Operating method for internal combustion engine and vehicle propelling system
US20170058816A1 (en) * 2015-09-02 2017-03-02 Mazda Motor Corporation Control apparatus of engine
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JP2019194456A (en) * 2018-05-02 2019-11-07 マツダ株式会社 Control device for compression ignition type engine
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JP2008144765A (en) * 2006-12-08 2008-06-26 Ford Global Technologies Llc Method and system for controlling engine provided with cylinders using electronic valve actuation
JP2008274954A (en) * 2007-05-07 2008-11-13 Ford Global Technologies Llc Operating method for internal combustion engine and vehicle propelling system
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JP2017048735A (en) * 2015-09-02 2017-03-09 マツダ株式会社 Control device for engine
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JP2017180437A (en) * 2016-03-31 2017-10-05 マツダ株式会社 Control device of engine
CN108779725A (en) * 2016-03-31 2018-11-09 马自达汽车株式会社 Engine control system
US10513990B2 (en) 2016-03-31 2019-12-24 Mazda Motor Corporation Engine control device
JP2019194457A (en) * 2018-05-02 2019-11-07 マツダ株式会社 Control device for compression ignition type engine
JP2019194456A (en) * 2018-05-02 2019-11-07 マツダ株式会社 Control device for compression ignition type engine
US11203969B2 (en) 2018-05-02 2021-12-21 Mazda Motor Corporation Control apparatus for compression-ignition type engine
US11220971B2 (en) 2018-05-02 2022-01-11 Mazda Motor Corporation Control apparatus for compression-ignition type engine
US11220972B2 (en) 2018-05-02 2022-01-11 Mazda Motor Corporation Control apparatus for compression-ignition type engine
JP7043960B2 (en) 2018-05-02 2022-03-30 マツダ株式会社 Compression ignition engine controller
JP7043961B2 (en) 2018-05-02 2022-03-30 マツダ株式会社 Compression ignition engine controller
US11326543B2 (en) 2018-05-02 2022-05-10 Mazda Motor Corporation Control apparatus for compression-ignition type engine
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