JP2009074488A - Control device for internal combustion engine - Google Patents

Control device for internal combustion engine Download PDF

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JP2009074488A
JP2009074488A JP2007245568A JP2007245568A JP2009074488A JP 2009074488 A JP2009074488 A JP 2009074488A JP 2007245568 A JP2007245568 A JP 2007245568A JP 2007245568 A JP2007245568 A JP 2007245568A JP 2009074488 A JP2009074488 A JP 2009074488A
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fuel
amount
region
combustion engine
internal combustion
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Hiroshi Sakai
洋志 坂井
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Toyota Motor Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/3011—Controlling fuel injection according to or using specific or several modes of combustion
    • F02D41/3017—Controlling fuel injection according to or using specific or several modes of combustion characterised by the mode(s) being used
    • F02D41/3023—Controlling fuel injection according to or using specific or several modes of combustion characterised by the mode(s) being used a mode being the stratified charge spark-ignited mode
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device capable of restraining the generation amount of nitrogen oxides even when a load of an internal combustion engine is large in a control device for an internal combustion engine wherein a premix region for HCCI combustion is formed by fuel injection of a first fuel amount, a stratified region is formed in the premix region by fuel injection of a second fuel amount, and ignition is performed. <P>SOLUTION: Generally, an air-fuel mixture with an air-fuel ratio easily generating nitrogen oxides is formed in a boundary region between the premix region and the stratified region. The larger a load (required fuel injection amount Fi) is, the higher an inner cylinder temperature is and the larger a generation amount of nitrogen oxides from the boundary region is. When the required fuel injection amount Fi is larger than a prescribed amount, this device sets the first fuel amount to be zero and the second fuel amount to be the required fuel injection amount Fi. A second stratified region (volume V2>V1) with rich air-fuel ratio is formed as a substitute for a first stratified region (volume V1). The farther a position of the air-fuel mixture is separated from an ignition plug, the lower a combustion temperature of the air-fuel mixture is. Therefore, even when the load is increased, rise of the temperature of the boundary region can be restrained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、内燃機関の制御装置に関する。   The present invention relates to a control device for an internal combustion engine.

近年、内燃機関におけるＮＯｘの発生量を低減する等のために、以下のような燃焼形態が提案されてきている。圧縮上死点近傍よりも早期に燃料が噴射され、燃焼室内に燃料濃度が略均一な混合気の予混合領域が形成される。この混合気が圧縮上死点近傍にて自着火させられる。以下、この燃焼形態を、「ＨＣＣＩ（homogeneous charge compression ignition）燃焼」と称呼する。   In recent years, the following combustion modes have been proposed in order to reduce the amount of NOx generated in an internal combustion engine. Fuel is injected earlier than the vicinity of the compression top dead center, and a premixed region of air-fuel mixture having a substantially uniform fuel concentration is formed in the combustion chamber. This air-fuel mixture is self-ignited near the compression top dead center. Hereinafter, this combustion mode is referred to as “HCCI (homogeneous charge compression ignition) combustion”.

係るＨＣＣＩ燃焼においては、筒内温度の変動等に起因して、混合気の自着火時期がサイクル毎に変動する場合がある。これに対処するため、下記特許文献１に記載の制御装置は、点火プラグを用いて混合気の自着火をアシストするようになっている。これにより、上記自着火時期の変動の程度が抑制され得る。
特開２００４−２８５９２５号公報 In such HCCI combustion, due to fluctuations in the in-cylinder temperature, the self-ignition timing of the air-fuel mixture may vary from cycle to cycle. In order to cope with this, the control device described in Patent Document 1 described below uses a spark plug to assist the self-ignition of the air-fuel mixture. Thereby, the fluctuation | variation degree of the said self-ignition timing can be suppressed.
JP 2004-285925 A

ところで、ＨＣＣＩ燃焼を実行する内燃機関では、一般に、吸入新気量が一定となるような状態のもとで、アクセル操作量等に基づいて要求燃料噴射量が決定される場合が多い。この場合、要求燃料噴射量が小さいほど内燃機関の負荷がより小さくなる。また、噴射される燃料量（即ち、要求燃料噴射量）が小さいほど、予混合領域における平均空燃比（予混合領域中に含まれる燃料量（この場合、要求燃料噴射量）に対する筒内に吸入された新気量の割合）のリーン度合いがより大きくなる。   By the way, in an internal combustion engine that performs HCCI combustion, generally, the required fuel injection amount is often determined based on an accelerator operation amount or the like under a state in which the intake fresh air amount is constant. In this case, the smaller the required fuel injection amount, the smaller the load on the internal combustion engine. Further, the smaller the amount of fuel injected (that is, the required fuel injection amount), the smaller the amount of fuel that is sucked into the cylinder with respect to the average air-fuel ratio in the premix region (the fuel amount contained in the premix region (in this case, the required fuel injection amount) The degree of leanness of the ratio of the amount of fresh air generated becomes larger.

従って、内燃機関の負荷が小さい場合、予混合領域における平均空燃比のリーン度合いが大きいため、同平均空燃比が可燃範囲から逸脱し易い。以上のことから、上記ＨＣＣＩ燃焼を実行する内燃機関において、内燃機関の負荷が小さい場合、上述のように点火プラグによるアシストがなされても、失火が発生し易い。   Therefore, when the load on the internal combustion engine is small, the lean degree of the average air-fuel ratio in the premixed region is large, and the average air-fuel ratio tends to deviate from the combustible range. From the above, in the internal combustion engine that performs the HCCI combustion, if the load on the internal combustion engine is small, misfire is likely to occur even if the ignition plug assists as described above.

ＨＣＣＩ燃焼を実行する内燃機関においては、上述した理由による失火を回避する観点から、例えば、上記予混合領域内であって点火プラグの周りに可燃混合気の成層領域を形成する燃料噴射制御が考えられる。ここで、上記「成層領域」は、燃料濃度が略均一な混合気の領域であって、同領域内における平均空燃比（同領域中に含まれる燃料量に対する同領域中に含まれる新気量の割合）が、同領域外におけるものと異なる領域を意味する。   In an internal combustion engine that performs HCCI combustion, from the viewpoint of avoiding misfire due to the above-described reason, for example, fuel injection control in which a stratified region of a combustible mixture is formed around the spark plug in the premixed region is considered. It is done. Here, the “stratified region” is a region of an air-fuel mixture having a substantially uniform fuel concentration, and the average air-fuel ratio in the region (the amount of fresh air included in the region relative to the amount of fuel included in the region). Means a region different from that outside the region.

図１１は、内燃機関の燃焼室内にて予混合領域、及び成層領域が形成される様子を示した図である。以下、図１１を参照しながら、上記燃料噴射制御、及び点火制御の一例について説明する。図１１（Ａ）に示したように、この内燃機関の燃焼室は、ピストン、シリンダ内壁面等により区画されている。内燃機関には、燃焼室内に直接燃料（この例ではガソリン）が噴射されるように、筒内噴射弁が配置されている。また、燃焼室の天井には、点火プラグが配置されている。   FIG. 11 is a diagram illustrating a state in which a premixing region and a stratification region are formed in the combustion chamber of the internal combustion engine. Hereinafter, an example of the fuel injection control and the ignition control will be described with reference to FIG. As shown in FIG. 11A, the combustion chamber of the internal combustion engine is partitioned by a piston, a cylinder inner wall surface, and the like. The internal combustion engine is provided with an in-cylinder injection valve so that fuel (in this example, gasoline) is directly injected into the combustion chamber. An ignition plug is disposed on the ceiling of the combustion chamber.

先ず、所定の燃料噴射時期にて、図示しないポート噴射弁から吸気通路へ燃料が噴射される。吸気行程にて上記噴射された燃料を含むガスが燃焼室内に吸入される。これにより、混合気の予混合領域が燃焼室内に形成される（微細なドットの部分を参照）。本例では、上記噴射される燃料の量は、上記要求燃料噴射量の半分よりも大きい量に設定される。また、想定され得る運転状態の範囲内において、予混合領域における平均空燃比が２０よりも大きくなるように、予混合領域が形成される。これは、予混合領域から発生するＮＯｘの量を抑制する観点に基づく。   First, at a predetermined fuel injection timing, fuel is injected from a port injection valve (not shown) into the intake passage. The gas containing the injected fuel is sucked into the combustion chamber in the intake stroke. As a result, a premixed region of the air-fuel mixture is formed in the combustion chamber (see the fine dot portion). In this example, the amount of fuel to be injected is set to an amount larger than half of the required fuel injection amount. In addition, the premixing region is formed so that the average air-fuel ratio in the premixing region is greater than 20 within the range of operating conditions that can be assumed. This is based on the viewpoint of suppressing the amount of NOx generated from the premixed region.

次に、圧縮行程の所定の燃料噴射時期にて、筒内噴射弁から燃焼室内に燃料が直接噴射される。これにより、上記予混合領域内であって点火プラグの周りに、成層領域が形成される（斜線の部分を参照）。本例では、成層領域における平均空燃比が理論空燃比よりもリッチとなるように、成層領域の体積が小さくなるよう成層領域が形成される。これは、要求燃料噴射量が小さい場合であっても失火を回避するとともに、成層領域から発生するＮＯｘの量をも抑制する観点に基づく。   Next, fuel is directly injected into the combustion chamber from the in-cylinder injection valve at a predetermined fuel injection timing in the compression stroke. As a result, a stratified region is formed in the premixed region and around the spark plug (see the hatched portion). In this example, the stratification region is formed so that the volume of the stratification region becomes smaller so that the average air-fuel ratio in the stratification region becomes richer than the theoretical air-fuel ratio. This is based on the viewpoint of avoiding misfire even when the required fuel injection amount is small and suppressing the amount of NOx generated from the stratified region.

そして、圧縮上死点近傍にて点火プラグによる点火が行われる。以上により、内燃機関の負荷が小さい場合であっても、成層領域の混合気が燃焼するとともに、平均空燃比のリーン度合いが大きい予混合領域の混合気も燃焼し得る。従って、失火を回避することができる。   Then, ignition by a spark plug is performed near the compression top dead center. As described above, even when the load of the internal combustion engine is small, the air-fuel mixture in the stratified region burns, and the air-fuel mixture in the premixed region where the lean degree of the average air-fuel ratio is large can also burn. Therefore, misfire can be avoided.

ところで、図１２に示したように、一般に、混合気の空燃比が理論空燃比よりもリーン側の所定の範囲内にある場合、燃焼の際に比較的大きい量のＮＯｘが発生し易い傾向がある。以下、比較的大きい量のＮＯｘが発生し易い空燃比の範囲を「ＮＯｘ発生範囲」と称呼する。例えば、燃料がガソリンである場合、上記ＮＯｘ発生範囲は１６〜２０である。また、この傾向は混合気の温度が高いほどより顕著になる。   Incidentally, as shown in FIG. 12, generally, when the air-fuel ratio of the air-fuel mixture is within a predetermined range leaner than the stoichiometric air-fuel ratio, a relatively large amount of NOx tends to be generated during combustion. is there. Hereinafter, an air-fuel ratio range in which a relatively large amount of NOx is likely to be generated is referred to as a “NOx generation range”. For example, when the fuel is gasoline, the NOx generation range is 16-20. This tendency becomes more remarkable as the temperature of the air-fuel mixture increases.

燃焼室のシリンダ径方向断面図である図１１（Ｂ）に示したように、予混合領域内に成層領域が形成されると、境界領域が形成される。ここで、上記「境界領域」は、２つの領域の境界近傍において、両方の領域のガスが混ざり合う部分を意味する。また、上述したように、予混合領域における平均空燃比は２０よりも大きく、且つ、成層領域における平均空燃比が理論空燃比よりもリッチである。このため、上記境界領域内には、上記ＮＯｘ発生範囲内の空燃比をもった混合気が存在する。   As shown in FIG. 11B, which is a sectional view in the cylinder radial direction of the combustion chamber, when a stratified region is formed in the premixed region, a boundary region is formed. Here, the “boundary region” means a portion where the gases of both regions are mixed in the vicinity of the boundary between the two regions. Further, as described above, the average air-fuel ratio in the premixed region is greater than 20, and the average air-fuel ratio in the stratified region is richer than the stoichiometric air-fuel ratio. Therefore, an air-fuel mixture having an air-fuel ratio within the NOx generation range exists in the boundary region.

一方、内燃機関の負荷が大きいほど筒内のピーク温度がより高くなる。筒内のピーク温度が高いほど境界領域の温度がより高くなる。従って、内燃機関の負荷が大きい場合、上記境界領域から大きい量のＮＯｘが発生する。   On the other hand, the greater the load on the internal combustion engine, the higher the peak temperature in the cylinder. The higher the peak temperature in the cylinder, the higher the temperature in the boundary region. Therefore, when the load on the internal combustion engine is large, a large amount of NOx is generated from the boundary region.

このように、予混合領域内に成層領域を形成することで、境界領域内にて上記ＮＯｘ発生範囲内の空燃比をもつ混合気が存在すると、内燃機関の負荷が大きい場合、境界領域から発生するＮＯｘの量が大きくなるという問題があった。   In this way, by forming a stratification region in the premixing region, if there is an air-fuel mixture having an air-fuel ratio within the NOx generation range in the boundary region, it is generated from the boundary region when the load on the internal combustion engine is large. There was a problem that the amount of NOx to be increased.

従って、本発明の目的は、予混合領域を形成して、予混合領域内であって点火プラグの周りに成層領域を形成するように燃料の噴射形態を制御し、点火プラグの点火制御を行う内燃機関の制御装置において、内燃機関の負荷が大きい場合であっても、内燃機関におけるＮＯｘの発生量を抑制することができるものを提供することにある。   Accordingly, an object of the present invention is to control the injection mode of the fuel so as to form a premixing region, form a stratified region around the spark plug in the premixing region, and perform ignition control of the spark plug. An object of the present invention is to provide a control device for an internal combustion engine that can suppress the amount of NOx generated in the internal combustion engine even when the load on the internal combustion engine is large.

本発明に係る第１の制御装置は、筒内噴射弁、又は、筒内噴射弁及びポート噴射弁と、点火プラグとを備えた内燃機関に適用される。   A first control device according to the present invention is applied to an in-cylinder injection valve or an internal combustion engine including an in-cylinder injection valve and a port injection valve, and an ignition plug.

本発明に係る第１の制御装置は、前記内燃機関の運転状態に基づいて要求燃料噴射量を決定する要求燃料噴射量決定手段と、第１燃料噴射時期にて前記筒内噴射弁又は前記ポート噴射弁から前記決定された要求燃料噴射量の半分よりも大きい第１燃料量の燃料を噴射して混合気の予混合領域を形成し、前記第１燃料噴射時期よりも後の第２燃料噴射時期にて前記筒内噴射弁から前記要求燃料噴射量から前記第１燃料量を除いた残りの量である第２燃料量の燃料を噴射して前記予混合領域内であって前記点火プラグの周りに混合気の第１成層領域を形成する噴射形態制御手段と、前記第２燃料噴射時期よりも後にて前記点火プラグにて点火を行う点火制御手段とを備えている。   The first control device according to the present invention includes a required fuel injection amount determining means for determining a required fuel injection amount based on an operating state of the internal combustion engine, and the in-cylinder injection valve or the port at a first fuel injection timing. A fuel with a first fuel amount larger than half of the determined required fuel injection amount is injected from the injection valve to form a premixed region of the air-fuel mixture, and a second fuel injection after the first fuel injection timing A fuel of a second fuel amount, which is the remaining amount obtained by subtracting the first fuel amount from the required fuel injection amount, is injected from the in-cylinder injection valve at the timing, and is in the premixing region and the spark plug An injection mode control means for forming a first stratified region of the air-fuel mixture is provided, and an ignition control means for igniting with the spark plug after the second fuel injection timing.

本発明に係る第１の制御装置の特徴は、前記噴射形態制御手段が、前記要求燃料噴射量に基づく前記内燃機関の負荷を表す値が第１所定値よりも大きい場合、前記第１燃料量をゼロに、前記第２燃料量を前記要求燃料噴射量と等しい量に設定して、（前記予混合領域内に前記第１成層領域を形成するのに代えて）前記燃焼室内に吸入されたガス中に、前記第１成層領域よりも体積が大きい混合気の第２成層領域であって前記第２燃料量に対する前記第２成層領域中に含まれる空気量の割合が理論空燃比よりもリッチな第２成層領域を形成するように構成されたことにある。   A feature of the first control device according to the present invention is that when the injection form control means has a value representing a load of the internal combustion engine based on the required fuel injection amount larger than a first predetermined value, the first fuel amount. Was set to zero and the second fuel amount was set equal to the required fuel injection amount, and was sucked into the combustion chamber (instead of forming the first stratified region in the premixed region) The ratio of the amount of air contained in the second stratification region with respect to the second fuel amount is richer than the stoichiometric air-fuel ratio in the gas in the second stratification region of the gas mixture having a volume larger than that of the first stratification region. In other words, the second stratified region is formed.

上記「内燃機関の負荷を表す値」は、例えば、前記要求燃料噴射量の燃料の燃焼により発生する前記内燃機関の駆動トルク、前記要求燃料噴射量そのもの等であり、これらに限定されない。   The “value indicating the load of the internal combustion engine” is, for example, the drive torque of the internal combustion engine generated by the combustion of the fuel of the required fuel injection amount, the required fuel injection amount itself, and the like, but is not limited thereto.

これにより、前記内燃機関の負荷を表す値が第１所定値よりも大きい場合、前記燃焼室内に吸入された（燃料を含まない）ガスと第２成層領域との境界領域内に、上記ＮＯｘ発生範囲内の空燃比をもった混合気が存在するようになる。また、予混合領域と第１成層領域との境界領域に比して、燃焼室内に吸入されたガスと第２成層領域との境界領域の、点火プラグからの乖離の程度が大きくなる。   Thereby, when the value representing the load of the internal combustion engine is larger than the first predetermined value, the NOx is generated in the boundary region between the gas sucked into the combustion chamber (not including fuel) and the second stratified region. An air-fuel mixture having an air-fuel ratio within the range is present. In addition, the degree of deviation from the spark plug in the boundary region between the gas sucked into the combustion chamber and the second stratification region is larger than that in the boundary region between the premixing region and the first stratification region.

ここで、燃焼室内において、混合気の位置が点火プラグから離れているほど、混合気の燃焼温度がより低くなる傾向がある。従って、内燃機関の負荷が一定の場合において、境界領域の点火プラグからの乖離の程度が大きいほど、境界領域での燃焼温度がより低くなる。従って、上記構成によれば、内燃機関の負荷を表す値が増大しても、境界領域の温度上昇が抑制され得る。この結果、内燃機関の負荷が大きい場合であっても、境界領域からのＮＯｘの発生量が抑制され得る。   Here, in the combustion chamber, as the position of the air-fuel mixture is farther from the spark plug, the combustion temperature of the air-fuel mixture tends to be lower. Therefore, when the load of the internal combustion engine is constant, the greater the degree of deviation from the spark plug in the boundary region, the lower the combustion temperature in the boundary region. Therefore, according to the said structure, even if the value showing the load of an internal combustion engine increases, the temperature rise of a boundary region can be suppressed. As a result, even when the load on the internal combustion engine is large, the amount of NOx generated from the boundary region can be suppressed.

また、第２燃料量に対する第２成層領域中に含まれる空気の割合は、理論空燃比よりもリッチである。従って、第２成層領域から発生するＮＯｘの量は極僅かとなり得る。以上のことから、内燃機関の負荷が大きい場合であっても、内燃機関におけるＮＯｘの発生量が抑制され得る。   Further, the ratio of air contained in the second stratification region to the second fuel amount is richer than the stoichiometric air-fuel ratio. Therefore, the amount of NOx generated from the second stratification region can be negligible. From the above, even when the load on the internal combustion engine is large, the amount of NOx generated in the internal combustion engine can be suppressed.

上記本発明に係る第１の制御装置においては、前記噴射形態制御手段が、前記負荷を表す値が前記第１所定値以上の第２所定値よりも大きい場合、（前記第１燃料量をゼロに設定するのに代えて）前記第１燃料量をゼロでない所定量に、（前記第２燃料量を要求燃料噴射量と等しい量に設定するのに代えて）前記第２燃料量を前記要求燃料噴射量よりも前記所定量だけ小さい量に設定して、（前記燃焼室内に吸入されたガス中に前記第２成層領域を形成するのに代えて）前記予混合領域内に前記第２成層領域を形成するように構成されることが好適である。   In the first control device according to the present invention, when the injection form control means has a value representing the load greater than a second predetermined value equal to or greater than the first predetermined value (the first fuel amount is set to zero). The first fuel amount to a predetermined non-zero amount (instead of setting the second fuel amount to an amount equal to the required fuel injection amount) and the second fuel amount to the required amount. The second stratification is set in the premix region (instead of forming the second stratification region in the gas sucked into the combustion chamber) by setting the amount smaller than the fuel injection amount by the predetermined amount. Suitably configured to form a region.

第２燃料量が大きいほど第２成層領域における平均空燃比のリッチ度合いがより大きくなる。この平均空燃比のリッチ度合いが大きいほど、第２成層領域からの未燃ＨＣ，ＣＯの発生量がより大きくなる。即ち、第２燃料量が大きいほど、第２成層領域からの未燃ＨＣ，ＣＯの発生量がより大きくなる傾向がある。   As the second fuel amount increases, the degree of richness of the average air-fuel ratio in the second stratification region increases. The greater the degree of richness of this average air-fuel ratio, the greater the amount of unburned HC and CO generated from the second stratified region. That is, as the second fuel amount increases, the amount of unburned HC and CO generated from the second stratified region tends to increase.

上記構成によれば、前記内燃機関の負荷が大きい場合であっても、第２燃料量が小さい量に設定され得、第２成層領域からの未燃ＨＣ，ＣＯの発生量が抑制され得る。この結果、内燃機関の負荷の増大に伴う内燃機関の燃費の低下を抑制することができる。   According to the above configuration, even when the load on the internal combustion engine is large, the second fuel amount can be set to a small amount, and the amount of unburned HC and CO generated from the second stratified region can be suppressed. As a result, it is possible to suppress a decrease in fuel consumption of the internal combustion engine accompanying an increase in the load of the internal combustion engine.

この場合、前記噴射形態制御手段が、前記負荷を表す値が前記第２所定値よりも大きい場合、前記負荷を表す値と前記第２所定値との相違の程度が大きいほど前記所定量が大きくなるように、前記第１及び第２燃料量を設定するよう構成されると更に好適である。これによれば、第２成層領域からの未燃ＨＣ，ＣＯの発生量をより確実に抑制することができる。   In this case, when the value representing the load is larger than the second predetermined value, the injection form control means increases the predetermined amount as the degree of difference between the value representing the load and the second predetermined value increases. Thus, it is more preferable that the first and second fuel amounts are set. According to this, the amount of unburned HC and CO generated from the second stratified region can be more reliably suppressed.

また、上記本発明に係る第１の制御装置においては、前記内燃機関が、前記燃焼室内に不活性ガスを噴射する不活性ガス噴射弁を備え、第１の制御装置が、前記負荷を表す値が前記第１所定値よりも大きい場合、前記第２成層領域内の混合気の燃焼中にて、前記不活性ガス噴射弁から前記不活性ガスを噴射する不活性ガス噴射制御手段を備えると好適である。   In the first control device according to the present invention, the internal combustion engine includes an inert gas injection valve that injects an inert gas into the combustion chamber, and the first control device is a value that represents the load. Is preferably larger than the first predetermined value, it is preferable to provide an inert gas injection control means for injecting the inert gas from the inert gas injection valve during combustion of the air-fuel mixture in the second stratified region. It is.

内燃機関における未燃ＨＣ，ＣＯの排出量を抑制するためには、前記第２成層領域内の混合気の燃焼中に発生する未燃ＨＣ，ＣＯを酸化させることも考えられる。このためには、例えば、上記発生する未燃ＨＣ，ＣＯと、第２成層領域以外の燃焼室内に存在する酸素とが混合されればよい。   In order to suppress the discharge amount of unburned HC and CO in the internal combustion engine, it is conceivable to oxidize unburned HC and CO generated during combustion of the air-fuel mixture in the second stratified region. For this purpose, for example, the unburned HC and CO generated above may be mixed with oxygen existing in the combustion chamber other than the second stratified region.

上記構成は係る知見に基づく。これによれば、噴射された不活性ガスが、上記発生する未燃ＨＣ，ＣＯ及び上記酸素の一方を巻き込んで、他方に向かって流動し得る。従って、上記発生する未燃ＨＣ，ＣＯ及び上記酸素の混合が促進され得る。この結果、内燃機関の負荷が大きい場合であっても、内燃機関における未燃ＨＣ，ＣＯの排出量が抑制され得る。なお、前記不活性ガスそのものが反応して燃焼に及ぼす影響は極僅かである。   The above configuration is based on such knowledge. According to this, the injected inert gas can entrain one of the generated unburned HC, CO and the oxygen and flow toward the other. Therefore, mixing of the generated unburned HC, CO and the oxygen can be promoted. As a result, even when the load on the internal combustion engine is large, the discharge amount of unburned HC and CO in the internal combustion engine can be suppressed. Note that the influence of the inert gas itself on the reaction is negligible.

この場合、前記不活性ガス噴射制御手段が、前記内燃機関の運転状態と、燃料の燃焼開始時期からの燃料の燃焼による熱発生率の積算値が前記燃焼開始時期から燃料の燃焼終了時期までの熱発生率の積算値の９０％に達する時期と、の関係を規定するデータを記憶するデータ記憶手段を備え、前記内燃機関の運転状態と、前記データとに基づいて得られる前記熱発生率の積算値の９０％に達する時期にて、前記不活性ガスを噴射するように構成されると更に好適である。   In this case, the inert gas injection control means is configured so that the integrated value of the operating state of the internal combustion engine and the heat release rate due to fuel combustion from the fuel combustion start timing is from the combustion start timing to the fuel combustion end timing. Data storage means for storing data defining the relationship between the time when the integrated value of the heat generation rate reaches 90%, and the heat generation rate obtained based on the operating state of the internal combustion engine and the data It is more preferable that the inert gas is injected at a time when 90% of the integrated value is reached.

本発明者は、種々の実験等により、燃料の燃焼開始時期からの燃料の燃焼による熱発生率の積算値が前記燃焼開始時期から燃料の燃焼終了時期までの熱発生率の積算値の９０％に達する時期よりも、不活性ガスの噴射時期が進角側であるほどＮＯｘの発生が顕著となり、同熱発生率の積算値の９０％に達する時期よりも不活性ガスの噴射時期が遅角側であるほど未燃ＨＣ，ＣＯの発生が顕著となる傾向があることを見出した。   Based on various experiments, the inventor has found that the integrated value of the heat generation rate due to fuel combustion from the fuel combustion start time is 90% of the integrated value of the heat generation rate from the combustion start time to the fuel combustion end time. As the inert gas injection timing is advanced, the NOx generation becomes more prominent than the timing when the gas reaches the initial value, and the inert gas injection timing is retarded from the timing when it reaches 90% of the integrated value of the heat generation rate. It was found that there is a tendency that unburned HC and CO are more prominent the closer to the side.

従って、ＮＯｘの発生量、及び未燃ＨＣ，ＣＯの排出量の両方を抑制する観点から、上記熱発生率の積算値の９０％に達する時期にて不活性ガスを噴射するのが好適である。上記構成は係る知見に基づく。これによれば、ＮＯｘの発生量が抑制されつつ、未燃ＨＣ，ＣＯの排出量も抑制され得る。   Therefore, from the viewpoint of suppressing both the amount of NOx generated and the amount of unburned HC and CO emitted, it is preferable to inject the inert gas at a time when it reaches 90% of the integrated value of the heat generation rate. . The above configuration is based on such knowledge. According to this, the emission amount of unburned HC and CO can be suppressed while the generation amount of NOx is suppressed.

本発明に係る第２の制御装置は、筒内噴射弁、又は、筒内噴射弁及びポート噴射弁と、点火プラグとを備えた内燃機関に適用される。   The second control device according to the present invention is applied to an in-cylinder injection valve or an internal combustion engine including an in-cylinder injection valve and a port injection valve, and an ignition plug.

本発明に係る第２の制御装置は、前記要求燃料噴射量を決定する要求燃料噴射量決定手段と、第１燃料噴射時期にて前記筒内噴射弁又は前記ポート噴射弁から前記第１燃料量の燃料を噴射して混合気の予混合領域を形成し、前記第２燃料噴射時期にて前記筒内噴射弁から前記第２燃料量の燃料を噴射して前記予混合領域内であって前記点火プラグの周りに混合気の成層領域を形成する噴射形態制御手段と、前記第２燃料噴射時期よりも後にて前記点火プラグにて点火を行う点火制御手段とを備えている。   The second control device according to the present invention includes a required fuel injection amount determining means for determining the required fuel injection amount, and the first fuel amount from the in-cylinder injection valve or the port injection valve at a first fuel injection timing. To inject the second fuel amount from the in-cylinder injection valve at the second fuel injection timing, and in the premixing region. The injection mode control means for forming a stratified region of the air-fuel mixture around the spark plug and the ignition control means for igniting the spark plug after the second fuel injection timing are provided.

本発明に係る第２の制御装置が適用される内燃機関が備える前記筒内噴射弁は、前記予混合領域と、前記成層領域との境界領域に向けて燃料を噴射するように配置されている。   The in-cylinder injection valve provided in the internal combustion engine to which the second control device according to the present invention is applied is arranged so as to inject fuel toward a boundary region between the premixing region and the stratification region. .

本発明に係る第２の制御装置の特徴は、前記噴射形態制御手段が、前記要求燃料噴射量に基づく前記内燃機関の負荷を表す値が第１所定値よりも大きい場合、前記点火を行う時期よりも前の第３燃料噴射時期にて、前記第２燃料量の一部である第３燃料量の燃料を噴射して、前記成層領域と体積が等しい混合気の成層領域を形成し、前記第３燃料噴射時期よりも後であって前記点火を行う時期よりも前の第４燃料噴射時期にて、前記第２燃料量から前記第３燃料量を除いた残りの量である第４燃料量の燃料を噴射するように構成されたことにある。   The second control device according to the present invention is characterized in that the injection mode control means performs the ignition when the value representing the load of the internal combustion engine based on the required fuel injection amount is larger than a first predetermined value. Before the third fuel injection timing, a third fuel amount of fuel that is a part of the second fuel amount is injected to form a stratified region of an air-fuel mixture having the same volume as the stratified region, The fourth fuel that is the remaining amount obtained by subtracting the third fuel amount from the second fuel amount at the fourth fuel injection timing after the third fuel injection timing and before the ignition timing. It is configured to inject an amount of fuel.

これにより、前記内燃機関の負荷を表す値が第１所定値よりも大きい場合、第３燃料量の燃料噴射により、予混合領域と成層領域との境界領域が形成される。この境界領域に向けて第４燃料量の燃料が噴射される。上記構成によれば、第３燃料量の燃料噴射により形成される境界領域内において、混合気の空燃比のリッチ度合いが大きくなり得る。従って、同境界領域内において、上記ＮＯｘ発生範囲内の空燃比をもった混合気の量が小さくなり得る。この結果、上記境界領域から発生するＮＯｘの量を抑制することができる。   Thereby, when the value representing the load of the internal combustion engine is larger than the first predetermined value, the boundary region between the premix region and the stratified region is formed by the fuel injection of the third fuel amount. A fourth fuel amount of fuel is injected toward this boundary region. According to the above configuration, the richness of the air-fuel ratio of the air-fuel mixture can be increased within the boundary region formed by the fuel injection of the third fuel amount. Therefore, the amount of the air-fuel mixture having the air-fuel ratio within the NOx generation range can be reduced within the boundary region. As a result, the amount of NOx generated from the boundary region can be suppressed.

また、第４燃料量の燃料噴射によっても混合気の成層領域が形成される。即ち、同成層領域と予混合領域との境界領域が形成される。ここで、同境界領域においては、前記第４燃料噴射時期から所定期間経過後に、上記ＮＯｘ発生範囲内の空燃比をもった混合気が形成される。従って、この所定期間経過前に点火時期が到来するように、前記第４燃料噴射時期が設定されることで、第４燃料量の燃料噴射により形成される境界領域から発生するＮＯｘの量を抑制することができる。以上のことから、内燃機関の負荷が大きい場合であっても、内燃機関におけるＮＯｘの発生量が抑制され得る。   A stratified region of the air-fuel mixture is also formed by fuel injection of the fourth fuel amount. That is, a boundary region between the stratified region and the premixed region is formed. Here, in the boundary region, an air-fuel mixture having an air-fuel ratio within the NOx generation range is formed after a lapse of a predetermined period from the fourth fuel injection timing. Therefore, the amount of NOx generated from the boundary region formed by the fuel injection of the fourth fuel amount is suppressed by setting the fourth fuel injection timing so that the ignition timing comes before the predetermined period elapses. can do. From the above, even when the load on the internal combustion engine is large, the amount of NOx generated in the internal combustion engine can be suppressed.

上記本発明に係る第２の制御装置においては、前記噴射形態制御手段が、前記負荷を表す値が前記第１所定値以上の第２所定値よりも大きい場合、前記負荷を表す値と前記第２所定値との相違の程度が大きいほど前記第３燃料量が大きくなるように、前記第３及び第４燃料量を設定するよう構成されることが好適である。   In the second control device according to the present invention, when the injection form control means has a value representing the load greater than a second predetermined value equal to or greater than the first predetermined value, the value representing the load and the first Preferably, the third and fourth fuel amounts are set so that the third fuel amount increases as the degree of difference from the predetermined value increases.

上述のように第４燃料量の燃料噴射によっても、混合気の成層領域が形成される。この成層領域の平均空燃比のリッチ度合いは、第３燃料量の燃料噴射により形成される成層領域に比して大きくなり易い。これは、第４燃料量の燃料噴射が、第３燃料量の燃料噴射よりも後になされることに起因すると考えられる。   As described above, the stratified region of the air-fuel mixture is also formed by the fuel injection of the fourth fuel amount. The rich degree of the average air-fuel ratio in the stratification region is likely to be larger than that in the stratification region formed by fuel injection of the third fuel amount. This is considered due to the fact that the fuel injection of the fourth fuel amount is performed after the fuel injection of the third fuel amount.

第４燃料量が大きいほど、第４燃料量の燃料噴射により形成される成層領域における平均空燃比のリッチ度合いがより大きくなる。即ち、第４燃料量が大きいほど、同成層領域からの未燃ＨＣ，ＣＯの発生量がより大きくなる傾向がある。   As the fourth fuel amount increases, the rich degree of the average air-fuel ratio in the stratified region formed by fuel injection of the fourth fuel amount increases. That is, the larger the fourth fuel amount, the greater the amount of unburned HC and CO generated from the stratified region.

上記構成によれば、内燃機関の負荷が大きい場合であっても、第３燃料量が大きい量に設定されることで、第４燃料量が小さい量に設定され得る。従って、内燃機関の負荷が大きい場合であっても、第４燃料量の燃料噴射により形成される成層領域からの、未燃ＨＣ，ＣＯの発生量が抑制され得る。この結果、内燃機関の負荷の増大に伴う内燃機関の燃費の低下を抑制することができる。   According to the above configuration, even when the load on the internal combustion engine is large, the fourth fuel amount can be set to a small amount by setting the third fuel amount to a large amount. Therefore, even when the load of the internal combustion engine is large, the amount of unburned HC and CO generated from the stratified region formed by the fuel injection of the fourth fuel amount can be suppressed. As a result, it is possible to suppress a decrease in fuel consumption of the internal combustion engine accompanying an increase in the load of the internal combustion engine.

また、本発明に係る第２の制御装置においては、前記噴射形態制御手段が、前記第３燃料量が大きいほど、前記第３燃料噴射時期と前記第４燃料噴射時期との間隔が大きくなるように、前記第３及び第４燃料噴射時期を設定するよう構成されることが好適である。   In the second control apparatus according to the present invention, the injection mode control means may increase the interval between the third fuel injection timing and the fourth fuel injection timing as the third fuel amount increases. In addition, it is preferable that the third and fourth fuel injection timings are set.

第３燃料量の燃料噴射により形成された境界領域内においては、前記第３燃料噴射時期から所定期間経過後に、上記ＮＯｘ発生範囲の空燃比をもった混合気が形成される。同境界領域にて、上記ＮＯｘ発生範囲の空燃比の混合気の量を確実に小さくする観点から、同混合気が形成されたときに第４燃料量の燃料噴射がなされると好適である。   In the boundary region formed by the fuel injection of the third fuel amount, an air-fuel mixture having an air-fuel ratio in the NOx generation range is formed after a predetermined period has elapsed from the third fuel injection timing. From the viewpoint of reliably reducing the amount of air-fuel mixture in the NOx generation range in the boundary region, it is preferable that fuel injection of the fourth fuel amount is performed when the air-fuel mixture is formed.

ここで、第３燃料量が大きいほど、この所定期間はより長くなると考えられる。従って、上記構成によれば、前記第４燃料噴射時期を、上記ＮＯｘ発生範囲の空燃比をもった混合気が形成される時期に近づけることができる。この結果、第３燃料量の燃料噴射により形成される境界領域から発生するＮＯｘの量を、より確実に抑制することができる。   Here, it is considered that the predetermined period becomes longer as the third fuel amount is larger. Therefore, according to the above configuration, the fourth fuel injection timing can be brought close to the timing when the air-fuel mixture having the air-fuel ratio in the NOx generation range is formed. As a result, the amount of NOx generated from the boundary region formed by the fuel injection of the third fuel amount can be more reliably suppressed.

以下、本発明による内燃機関の制御装置の各実施形態について図面を参照しつつ説明する。   Hereinafter, embodiments of a control device for an internal combustion engine according to the present invention will be described with reference to the drawings.

（第１実施形態）
図１は、本発明の第１実施形態に係る内燃機関の制御装置を火花点火式多気筒（４気筒）内燃機関１０の概略構成を示している。この内燃機関１０は、シリンダブロック部２０と、シリンダヘッド部３０とを備えている。 (First embodiment)
FIG. 1 shows a schematic configuration of a spark ignition type multi-cylinder (four-cylinder) internal combustion engine 10 as an internal combustion engine control apparatus according to a first embodiment of the present invention. The internal combustion engine 10 includes a cylinder block portion 20 and a cylinder head portion 30.

シリンダブロック部２０は、円筒状のシリンダ２１と、ピストン２２とを備えている。シリンダヘッド部３０と、シリンダ２１の内壁面と、ピストン２２の頂面とにより燃焼室２３が区画されている。ピストン２２の頂面の中央付近には、キャビティ（凹部）２２ａが設けられている。   The cylinder block unit 20 includes a cylindrical cylinder 21 and a piston 22. A combustion chamber 23 is defined by the cylinder head 30, the inner wall surface of the cylinder 21, and the top surface of the piston 22. Near the center of the top surface of the piston 22, a cavity (concave portion) 22a is provided.

シリンダヘッド部３０は、点火プラグ３１と、吸気通路に燃料（ガソリン）を噴射するポート噴射弁３２と、燃焼室２３内に燃料を直接噴射する筒内噴射弁３３とを備えている。点火プラグ３１は、燃焼室２３の天井の中央付近に配設されている。   The cylinder head portion 30 includes an ignition plug 31, a port injection valve 32 that injects fuel (gasoline) into the intake passage, and an in-cylinder injection valve 33 that injects fuel directly into the combustion chamber 23. The spark plug 31 is disposed near the center of the ceiling of the combustion chamber 23.

内燃機関１０の吸気系統は、吸気通路の開口断面積を可変とするスロットル弁４１を備えている。スロットル弁４１は、図示しないスロットル弁４１のアクチュエータにより作動するようになっている。   The intake system of the internal combustion engine 10 includes a throttle valve 41 that makes the opening cross-sectional area of the intake passage variable. The throttle valve 41 is operated by an actuator (not shown) of the throttle valve 41.

また、内燃機関１０は、排気還流管５１を備えている。排気還流管５１は排気通路とスロットル弁４１よりも下流側の吸気通路とを連通している。排気還流管５１には、ＥＧＲ制御弁５２と、ＥＧＲクーラー５３とが介装されている。これらにより、排気ガスを還流させる通路（ＥＧＲ通路）が構成されている。ＥＧＲ制御弁５２は、再循環される排気ガス流量（ＥＧＲガス流量）を変更し得るようになっている。   The internal combustion engine 10 includes an exhaust gas recirculation pipe 51. The exhaust gas recirculation pipe 51 communicates the exhaust passage and the intake passage downstream of the throttle valve 41. An EGR control valve 52 and an EGR cooler 53 are interposed in the exhaust gas recirculation pipe 51. Thus, a passage (EGR passage) for recirculating the exhaust gas is configured. The EGR control valve 52 can change the recirculated exhaust gas flow rate (EGR gas flow rate).

点火プラグ３１、ポート噴射弁３２、筒内噴射弁３３、スロットル弁４１のアクチュエータ、及びＥＧＲ制御弁５２は、図示しない電気制御装置と電気的に接続されていて、電気制御装置の指示に応じて駆動信号が供給されるようになっている。   The spark plug 31, the port injection valve 32, the in-cylinder injection valve 33, the actuator of the throttle valve 41, and the EGR control valve 52 are electrically connected to an electric control device (not shown), and according to instructions from the electric control device. A drive signal is supplied.

（予混合領域及び成層領域の形成のための燃料噴射形態）
次に、上述のように構成された内燃機関１０の制御装置が行う制御、及び燃焼室２３内に形成される混合気の様子について説明する。 (Fuel injection form for formation of premixed region and stratified region)
Next, the control performed by the control device for the internal combustion engine 10 configured as described above and the state of the air-fuel mixture formed in the combustion chamber 23 will be described.

図１１に対応する図２に示したように、この装置は、原則的には、第１燃料量の燃料を噴射することで、混合気の予混合領域を燃焼室２３内に形成するようになっている。また、失火を回避するために、第２燃料量の燃料を噴射することで、予混合領域内に混合気の成層領域を形成するようになっている。そして、点火プラグ３１にて点火制御をして、ＨＣＣＩ燃焼のアシストを行うようになっている。加えて、後に詳述するように、ＮＯｘ発生量を抑制するため、要求燃料噴射量Fiに応じて成層領域の体積等を変更するよう燃料の噴射形態を制御するようになっている。   As shown in FIG. 2 corresponding to FIG. 11, in principle, this apparatus forms a premixed region of the air-fuel mixture in the combustion chamber 23 by injecting the fuel of the first fuel amount. It has become. Further, in order to avoid misfire, a stratified region of the air-fuel mixture is formed in the premixed region by injecting fuel of the second fuel amount. Then, ignition control is performed by the spark plug 31 to assist HCCI combustion. In addition, as will be described in detail later, in order to suppress the NOx generation amount, the fuel injection mode is controlled so as to change the volume of the stratified region or the like in accordance with the required fuel injection amount Fi.

この装置では、アクセル操作量、エンジン回転速度に基づいて要求燃料噴射量Fiが決定される。そして、決定された要求燃料噴射量Fiと、図３に示した要求燃料噴射量Fiと同要求燃料噴射量Fiに対する上記第１及び第２燃料量の割合との関係を規定するテーブルとに基づいて、上記要求燃料噴射量Fiに対する第１及び第２燃料量の割合が設定される。   In this device, the required fuel injection amount Fi is determined based on the accelerator operation amount and the engine speed. Then, based on the determined required fuel injection amount Fi and a table defining the relationship between the required fuel injection amount Fi and the ratio of the first and second fuel amounts to the required fuel injection amount Fi shown in FIG. Thus, the ratio of the first and second fuel amounts to the required fuel injection amount Fi is set.

先ず、要求燃料噴射量Fiが、第１要求燃料噴射量Fi1（第１所定値）以下である場合における制御について説明する。この場合、図２の左側に対応する制御が実行される。本例では、第１要求燃料噴射量Fi1は、発生するＮＯｘの量が適正範囲の最大量となる場合に対応する要求燃料噴射量Fiである。   First, the control when the required fuel injection amount Fi is equal to or less than the first required fuel injection amount Fi1 (first predetermined value) will be described. In this case, control corresponding to the left side of FIG. 2 is executed. In this example, the first required fuel injection amount Fi1 is the required fuel injection amount Fi corresponding to the case where the amount of NOx generated is the maximum amount in the appropriate range.

この場合、この装置では、図３に示したテーブルに基づいて、要求燃料噴射量Fiに対する第１燃料量の割合が９０％に設定され、要求燃料噴射量Fiに対する第２燃料量の割合が１０％に設定される。これは、ＨＣＣＩ燃焼の度合いを大きくする観点に基づく。   In this case, in this apparatus, based on the table shown in FIG. 3, the ratio of the first fuel amount to the required fuel injection amount Fi is set to 90%, and the ratio of the second fuel amount to the required fuel injection amount Fi is 10%. % Is set. This is based on the viewpoint of increasing the degree of HCCI combustion.

図４は、要求燃料噴射量Fiと第２燃料量との関係を示すグラフである。要求燃料噴射量Fiが上記第１要求燃料噴射量Fi1以下である場合、要求燃料噴射量Fiが増大すると、第１及び２燃料量は、９０：１０の一定の割合を維持しながら増大していくようになっている。   FIG. 4 is a graph showing the relationship between the required fuel injection amount Fi and the second fuel amount. When the required fuel injection amount Fi is equal to or less than the first required fuel injection amount Fi1, when the required fuel injection amount Fi increases, the first and second fuel amounts increase while maintaining a constant ratio of 90:10. It has come to go.

図１を参照しながら燃料の噴射形態の制御について説明する。吸気行程が開始すると、燃焼室２３内にガスが吸入されていく。このガス（以下、「筒内ガス」とも称呼する。）には、スロットル弁４１を介して吸入された新気と、排気還流管５１からＥＧＲ制御弁５２を介して吸入された（外部）ＥＧＲガスが含まれる。本例では、スロットル弁４１の開度が最大値（即ち、吸入される新気量が一定）に維持される。従って、吸入される新気量（質量）と吸入されるＥＧＲガス量（質量）の和に対するＥＧＲガス量の割合（即ち、ＥＧＲ率）は、運転状態に応じて電気制御装置により適宜制御されるＥＧＲ制御弁５２の開度に応じて変化する。   The control of the fuel injection mode will be described with reference to FIG. When the intake stroke starts, gas is sucked into the combustion chamber 23. This gas (hereinafter also referred to as “in-cylinder gas”) includes fresh air sucked through the throttle valve 41 and (external) EGR sucked from the exhaust gas recirculation pipe 51 through the EGR control valve 52. Contains gas. In this example, the opening degree of the throttle valve 41 is maintained at the maximum value (that is, the amount of fresh air to be sucked is constant). Accordingly, the ratio of the amount of EGR gas to the sum of the amount of fresh air (mass) to be sucked and the amount of mass of EGR (mass) to be sucked (that is, the EGR rate) is appropriately controlled by the electric control device according to the operating state. It changes according to the opening degree of the EGR control valve 52.

上記吸気行程又は同吸気行程直前の排気行程の所定の時期（第１燃料噴射時期）にて、ポート噴射弁３２から吸気通路に上記設定された第１燃料量の燃料が噴射される。上記吸気行程にて、同燃料と筒内ガスとの混合気が燃焼室２３内に吸入されて、同混合気が燃焼室２３内に広く行き渡っていく。これにより、燃料の濃度が略均一な混合気の予混合領域が形成される。この予混合領域の体積は、燃焼室２３の体積と同じとなる（図２の左側の微細なドットの部分を参照）。   At a predetermined timing (first fuel injection timing) of the intake stroke or immediately before the intake stroke (first fuel injection timing), the set fuel amount of the first fuel is injected from the port injection valve 32 into the intake passage. In the intake stroke, an air-fuel mixture of the fuel and the in-cylinder gas is sucked into the combustion chamber 23, and the air-fuel mixture spreads widely in the combustion chamber 23. Thereby, a premixed region of the air-fuel mixture having a substantially uniform fuel concentration is formed. The volume of the premixed region is the same as the volume of the combustion chamber 23 (see the fine dot portion on the left side of FIG. 2).

予混合領域における平均空燃比（第１燃料量（質量）に対する筒内に吸入される新気量（質量）の割合）は、新気量が一定であるため、第１燃料量が大きいほどリッチ度合いが大きくなる。本例では、想定される運転状態の範囲内において、予混合領域における平均空燃比が２０よりも大きくなるように、予混合領域が形成される。   The average air-fuel ratio (ratio of the amount of fresh air (mass) sucked into the cylinder with respect to the first fuel amount (mass)) in the premixing region becomes richer as the first fuel amount increases because the fresh air amount is constant. The degree increases. In this example, the premixing region is formed so that the average air-fuel ratio in the premixing region is larger than 20 within the range of the assumed operating state.

上記吸入行程を含む燃焼サイクル中の圧縮行程後半の（点火時期より前の）所定の時期（第２燃料噴射時期）にて、ピストン２２のキャビティ２２ａに向けて、筒内噴射弁３３から上記設定された第２燃料量の燃料が燃焼室２３内（即ち、予混合領域内）に噴射される。同燃料の燃料噴霧は点火プラグ３１の近傍に主として集まる。これにより、予混合領域内であって点火プラグ３１の周りに、燃料の濃度が略均一な混合気の第１成層領域が形成される（図２の左側の斜線の部分を参照）。   The setting from the in-cylinder injection valve 33 toward the cavity 22a of the piston 22 at a predetermined timing (second fuel injection timing) in the latter half of the compression stroke in the combustion cycle including the intake stroke (before the ignition timing). The second amount of fuel thus injected is injected into the combustion chamber 23 (that is, in the premixing region). The fuel spray of the fuel is mainly collected near the spark plug 31. As a result, a first stratification region of the air-fuel mixture having a substantially uniform fuel concentration is formed in the premixing region and around the spark plug 31 (see the hatched portion on the left side of FIG. 2).

第１成層領域における平均空燃比（第２燃料量（質量）に対する第１成層領域内に含まれる新気量（質量）の割合）も、第２燃料量が大きいほどリッチ度合いが大きくなる。本例では、第１成層領域が、小さい一定の体積Ｖ１をもつように形成される。これは、第２燃料量が小さい場合であっても、第１成層領域における平均空燃比を理論空燃比よりもリッチにし得、失火を回避し得る観点に基づく。   The average air-fuel ratio in the first stratification region (the ratio of the fresh air amount (mass) contained in the first stratification region to the second fuel amount (mass)) also increases as the second fuel amount increases. In this example, the first stratified region is formed to have a small constant volume V1. This is based on the viewpoint that even if the second fuel amount is small, the average air-fuel ratio in the first stratification region can be made richer than the stoichiometric air-fuel ratio, and misfire can be avoided.

その後、圧縮上死点近傍にて、点火プラグ３１による点火が行われる。上記第１及び第２燃料量の燃料噴射時期、及び点火時期は、運転状態に応じて調整される。この結果、第１成層領域の混合気が燃焼するとともに、平均空燃比のリーン度合いが大きい予混合領域の混合気も燃焼し得る。   Thereafter, ignition by the spark plug 31 is performed near the compression top dead center. The fuel injection timing and ignition timing of the first and second fuel amounts are adjusted according to the operating state. As a result, the air-fuel mixture in the first stratification region burns, and the air-fuel mixture in the premixing region where the lean degree of the average air-fuel ratio is large can also burn.

（ＮＯｘの発生量を抑制するための制御）
ところで、上述したように、燃料がガソリンである場合、比較的大きい量のＮＯｘが発生し易い空燃比の範囲（以下、「ＮＯｘ発生範囲」と称呼する。）は、１６〜２０となる（図１２を参照）。また、上述したように、予混合領域における平均空燃比は２０よりも大きく、且つ、第１成層領域における平均空燃比が理論空燃比よりもリッチである。従って、予混合領域と第１成層領域との境界領域内には、上記ＮＯｘ発生範囲内の空燃比をもった混合気が存在する。 (Control for suppressing NOx generation amount)
Incidentally, as described above, when the fuel is gasoline, the air-fuel ratio range in which a relatively large amount of NOx is likely to be generated (hereinafter referred to as “NOx generation range”) is 16 to 20 (FIG. 12). Further, as described above, the average air-fuel ratio in the premixed region is greater than 20, and the average air-fuel ratio in the first stratification region is richer than the stoichiometric air-fuel ratio. Accordingly, an air-fuel mixture having an air-fuel ratio within the NOx generation range exists in the boundary region between the premixed region and the first stratified region.

ここで、要求燃料噴射量Fiが大きいほど、筒内のピーク温度がより高くなる。筒内のピーク温度が高いほど、境界領域の温度が高くなる。境界領域の温度が高いほど、境界領域から発生するＮＯｘの量が大きくなる。即ち、要求燃料噴射量Fiが大きい場合、上記境界領域から大きい量のＮＯｘが発生する。なお、本例では、要求燃料噴射量Fiが、内燃機関１０の負荷を表す値となり得る。   Here, the greater the required fuel injection amount Fi, the higher the in-cylinder peak temperature. The higher the peak temperature in the cylinder, the higher the boundary region temperature. The higher the temperature of the boundary region, the larger the amount of NOx generated from the boundary region. That is, when the required fuel injection amount Fi is large, a large amount of NOx is generated from the boundary region. In this example, the required fuel injection amount Fi can be a value representing the load of the internal combustion engine 10.

そこで、この装置は、要求燃料噴射量Fiが大きい場合であっても、ＮＯｘの発生量を抑制するために、以下に説明する燃料の噴射形態の制御を行う。   Therefore, this apparatus controls the fuel injection mode described below in order to suppress the amount of NOx generated even when the required fuel injection amount Fi is large.

この装置では、要求燃料噴射量Fiが上記第１要求燃料噴射量Fi1よりも大きい場合、図２の右側に対応する制御が実行される。この場合、図３に示したテーブルに基づいて、要求燃料噴射量Fiに対する第１燃料量の割合がゼロに設定され、要求燃料噴射量Fiに対する第２燃料量の割合が１００％に設定される。   In this device, when the required fuel injection amount Fi is larger than the first required fuel injection amount Fi1, control corresponding to the right side of FIG. 2 is executed. In this case, based on the table shown in FIG. 3, the ratio of the first fuel amount to the required fuel injection amount Fi is set to zero, and the ratio of the second fuel amount to the required fuel injection amount Fi is set to 100%. .

この場合、図４に示すように、第１燃料量がゼロに設定され、第２燃料量が要求燃料噴射量Fiと等しい量に設定される。この場合、要求燃料噴射量Fiが増大していくと、第２燃料量のみ増大していく。このため、ポート噴射弁３２からの燃料噴射が行われずに、吸気行程にて筒内ガスのみが燃焼室２３内に吸入される。この結果、予混合領域が形成されない。   In this case, as shown in FIG. 4, the first fuel amount is set to zero, and the second fuel amount is set to an amount equal to the required fuel injection amount Fi. In this case, as the required fuel injection amount Fi increases, only the second fuel amount increases. Therefore, fuel injection from the port injection valve 32 is not performed, and only the in-cylinder gas is sucked into the combustion chamber 23 in the intake stroke. As a result, the premixed area is not formed.

また、この場合、上記設定された第２燃料量の燃料の噴射により、筒内ガス中に混合気の第２成層領域が形成される。この第２成層領域内の燃料濃度は略均一である。第２成層領域における平均空燃比（第２燃料量（質量）に対する第２成層領域内に含まれる新気量（質量）の割合）が理論空燃比よりもリッチとなるように、且つ、第２成層領域が上記体積Ｖ１よりも大きい一定の体積Ｖ２をもつように、第２成層領域が形成される。   In this case, the second stratified region of the air-fuel mixture is formed in the in-cylinder gas by the fuel injection of the second fuel amount set as described above. The fuel concentration in the second stratification region is substantially uniform. The average air-fuel ratio in the second stratification region (the ratio of the fresh air amount (mass) contained in the second stratification region to the second fuel amount (mass)) becomes richer than the stoichiometric air-fuel ratio, and the second The second stratified region is formed so that the stratified region has a constant volume V2 larger than the volume V1.

このため、筒内ガスと第２成層領域との間に形成される境界領域内には、上記ＮＯｘ発生範囲内の空燃比をもった混合気が存在する。また、予混合領域と第１成層領域との境界領域に比して、筒内ガスと第２成層領域との境界領域の点火プラグ３１からの乖離の程度は大きい。   For this reason, in the boundary region formed between the in-cylinder gas and the second stratification region, there is an air-fuel mixture having an air-fuel ratio within the NOx generation range. Further, the degree of deviation from the spark plug 31 in the boundary region between the in-cylinder gas and the second stratification region is larger than that in the boundary region between the premixing region and the first stratification region.

ここで、上述したように、要求燃料噴射量Fiが一定の場合、境界領域の点火プラグ３１からの乖離の程度が大きいほど、境界領域の温度がより低くなる傾向がある。従って、要求燃料噴射量Fiが第１要求燃料噴射量Fi1よりも大きくなる場合であっても、境界領域の温度上昇が抑制され得る。この結果、要求燃料噴射量Fiが第１要求燃料噴射量Fi1よりも大きい場合であっても、境界領域からのＮＯｘの発生量が抑制され得る。   Here, as described above, when the required fuel injection amount Fi is constant, the temperature of the boundary region tends to be lower as the degree of deviation from the spark plug 31 in the boundary region is larger. Therefore, even if the required fuel injection amount Fi is larger than the first required fuel injection amount Fi1, the temperature increase in the boundary region can be suppressed. As a result, even when the required fuel injection amount Fi is larger than the first required fuel injection amount Fi1, the amount of NOx generated from the boundary region can be suppressed.

また、第２成層領域における平均空燃比は、理論空燃比よりもリッチである。従って、第２成層領域から発生するＮＯｘの量は極僅かである。以上のことから、要求燃料噴射量Fiが第１要求燃料噴射量Fiよりも大きい場合であっても、ＮＯｘの発生量が上記適正範囲を超えることを防止することができる。   Further, the average air-fuel ratio in the second stratification region is richer than the theoretical air-fuel ratio. Therefore, the amount of NOx generated from the second stratification region is very small. From the above, even when the required fuel injection amount Fi is larger than the first required fuel injection amount Fi, it is possible to prevent the NOx generation amount from exceeding the appropriate range.

（未燃ＨＣ，ＣＯの発生量を抑制するための制御）
ところで、上述のように、要求燃料噴射量Fiが上記第１要求燃料噴射量Fi1よりも大きい場合に第２成層領域を形成する制御においては、第２燃料量（＝要求燃料噴射量Fi）が大きいほど、第２成層領域における平均空燃比のリッチ度合いが大きくなる。即ち、要求燃料噴射量Fiが大きいほど、第２成層領域から発生する未燃ＨＣ，ＣＯの量がより大きくなる。 (Control to reduce the amount of unburned HC and CO generated)
Incidentally, as described above, in the control for forming the second stratification region when the required fuel injection amount Fi is larger than the first required fuel injection amount Fi1, the second fuel amount (= required fuel injection amount Fi) is The greater the value, the greater the richness of the average air-fuel ratio in the second stratification region. That is, the larger the required fuel injection amount Fi, the larger the amount of unburned HC and CO generated from the second stratification region.

そこで、この装置は、要求燃料噴射量Fiが上記第１要求燃料噴射量Fi1よりも大きい場合において、要求燃料噴射量Fiが大きい場合であっても、未燃ＨＣ，ＣＯの発生量を抑制するために、以下に説明する燃料の噴射形態の制御を行う。   Therefore, this device suppresses the amount of unburned HC and CO generated even when the required fuel injection amount Fi is large when the required fuel injection amount Fi is larger than the first required fuel injection amount Fi1. Therefore, the fuel injection mode described below is controlled.

この装置では、要求燃料噴射量Fiが第２要求燃料噴射量Fi2（＞Fi1、第２所定値）よりも大きい場合、図３に示したテーブルに基づいて、要求燃料噴射量Fiが大きいほど、要求燃料噴射量Fiに対する第１燃料量の割合がより大きい割合に設定され、要求燃料噴射量Fiに対する第２燃料量の割合がより小さい割合に設定される。本例では、第２要求燃料噴射量Fi2は、発生する未燃ＨＣ，ＣＯの量が適正範囲の最大量となる場合に対応する要求燃料噴射量Fiである。   In this apparatus, when the required fuel injection amount Fi is larger than the second required fuel injection amount Fi2 (> Fi1, a second predetermined value), the larger the required fuel injection amount Fi, based on the table shown in FIG. The ratio of the first fuel amount to the required fuel injection amount Fi is set to a larger ratio, and the ratio of the second fuel amount to the required fuel injection amount Fi is set to a smaller ratio. In this example, the second required fuel injection amount Fi2 is the required fuel injection amount Fi corresponding to the case where the amount of generated unburned HC and CO is the maximum amount within the appropriate range.

この場合、図４に示すように、第１燃料量が、要求燃料噴射量Fiから第２要求燃料噴射量Fi2を減じた量（所定量）に設定され、第２燃料量が、第２要求燃料噴射量Fi2と等しい量に設定される。即ち、要求燃料噴射量Fiが第２要求燃料噴射量Fi2から増大していくと、第１燃料量はゼロから増大していく一方、第２燃料量は上記第２要求燃料噴射量Fi2に維持されるようになっている。   In this case, as shown in FIG. 4, the first fuel amount is set to an amount (predetermined amount) obtained by subtracting the second requested fuel injection amount Fi2 from the requested fuel injection amount Fi, and the second fuel amount is set to the second requested fuel amount. An amount equal to the fuel injection amount Fi2 is set. That is, when the required fuel injection amount Fi increases from the second required fuel injection amount Fi2, the first fuel amount increases from zero, while the second fuel amount is maintained at the second required fuel injection amount Fi2. It has come to be.

この場合、上記設定された第１燃料量の燃料の噴射により、予混合領域が形成されて、上記設定された第２燃料量の燃料の噴射により、上記予混合領域内に第２成層領域が形成されるように燃料の噴射形態が制御される。要求燃料噴射量Fiが第２要求燃料噴射量Fi2よりも大きくなる場合であっても、第２燃料量は第２要求燃料噴射量Fi2に維持されるため、第２成層領域における平均空燃比が一定に維持される。   In this case, a premixing region is formed by the fuel injection of the set first fuel amount, and a second stratification region is formed in the premixing region by the fuel injection of the second fuel amount set. The fuel injection mode is controlled so as to be formed. Even when the required fuel injection amount Fi is larger than the second required fuel injection amount Fi2, the second fuel amount is maintained at the second required fuel injection amount Fi2, so the average air-fuel ratio in the second stratification region is Maintained constant.

この結果、要求燃料噴射量Fiが第２要求燃料噴射量Fi2よりも大きい場合であっても、未燃ＨＣ，ＣＯの発生量が上記適正範囲を超えることを防止することができる。   As a result, even when the required fuel injection amount Fi is larger than the second required fuel injection amount Fi2, the amount of unburned HC and CO generated can be prevented from exceeding the appropriate range.

なお、予混合領域と第２成層領域との境界領域にも、上記ＮＯｘ発生範囲内の空燃比をもった混合気が存在する。この境界領域は、点火プラグ３１から大きく乖離している。従って、要求燃料噴射量Fiが上記第２要求燃料噴射量Fi2よりも大きくなる場合であっても、境界領域の温度上昇が抑制され得る。従って、この場合であっても、境界領域から発生するＮＯｘの量が抑制され得る。   Note that an air-fuel mixture having an air-fuel ratio within the NOx generation range also exists in the boundary region between the premixed region and the second stratified region. This boundary region is greatly deviated from the spark plug 31. Accordingly, even when the required fuel injection amount Fi is larger than the second required fuel injection amount Fi2, a temperature increase in the boundary region can be suppressed. Therefore, even in this case, the amount of NOx generated from the boundary region can be suppressed.

以上、説明したように、本発明の第１実施形態によれば、予混合領域内に第１成層領域を形成するように燃料噴射し、点火プラグにて点火するよう制御する内燃機関の制御装置において、要求燃料噴射量Fiが上記第１要求燃料噴射量Fi1よりも大きい場合、筒内ガス中（又は、予混合領域内）に第２成層領域が形成されるように燃料の噴射形態が制御される。第２成層領域の体積Ｖ２が第１成層領域の体積Ｖ１よりも大きく、第２成層領域における平均空燃比が理論空燃比よりもリッチとなるように、第２成層領域が形成される。   As described above, according to the first embodiment of the present invention, the control device for an internal combustion engine that controls to inject fuel so as to form the first stratification region in the premixing region and to ignite with the spark plug. When the required fuel injection amount Fi is larger than the first required fuel injection amount Fi1, the fuel injection mode is controlled so that the second stratification region is formed in the in-cylinder gas (or in the premixing region). Is done. The second stratification region is formed such that the volume V2 of the second stratification region is larger than the volume V1 of the first stratification region, and the average air-fuel ratio in the second stratification region is richer than the theoretical air-fuel ratio.

これにより、筒内ガス（又は、予混合領域）と第２成層領域との境界領域であって、上記ＮＯｘ発生範囲の空燃比をもつ混合気が存在する境界領域が、点火プラグ３１から大きく乖離する。従って、要求燃料噴射量Fiが上記第１要求燃料噴射量Fi1よりも大きくなる場合であっても、境界領域の温度上昇を抑制することができる。この結果、境界領域内から発生するＮＯｘの量を抑制できる。また、第２成層領域における平均空燃比は理論空燃比よりもリッチであるから、第２成層領域から発生するＮＯｘは極僅かとなり得る。以上のことから、要求燃料噴射量Fiが大きい場合であっても、内燃機関１０において発生するＮＯｘの量を抑制することができる。   As a result, the boundary region between the in-cylinder gas (or the premixing region) and the second stratification region, where the air-fuel mixture having the air-fuel ratio in the NOx generation range exists, is greatly deviated from the spark plug 31. To do. Therefore, even when the required fuel injection amount Fi is larger than the first required fuel injection amount Fi1, a temperature increase in the boundary region can be suppressed. As a result, the amount of NOx generated from the boundary region can be suppressed. Further, since the average air-fuel ratio in the second stratification region is richer than the stoichiometric air-fuel ratio, NOx generated from the second stratification region can be very small. From the above, even when the required fuel injection amount Fi is large, the amount of NOx generated in the internal combustion engine 10 can be suppressed.

本発明は、上記第１実施形態に限定されることはなく、本発明の範囲内において種々の変形例を採用することができる。例えば、上記第１実施形態においては、図２（Ａ）に対応する図５（Ａ）に示したように、内燃機関１０が、燃焼室２３内に窒素（不活性ガス）を噴射する窒素噴射弁３４（不活性ガス噴射弁）を備えていてもよい。この場合、窒素噴射弁３４には、第２成層領域外に位置する噴孔であって、同噴孔からの窒素の噴射方向の延長線が境界領域を貫通するような噴孔が少なくとも１つ備えられていると好適である。   The present invention is not limited to the first embodiment, and various modifications can be employed within the scope of the present invention. For example, in the first embodiment, as shown in FIG. 5A corresponding to FIG. 2A, the internal combustion engine 10 injects nitrogen (inert gas) into the combustion chamber 23. A valve 34 (inert gas injection valve) may be provided. In this case, the nitrogen injection valve 34 has at least one injection hole which is located outside the second stratification region, and an extension line in the injection direction of nitrogen from the injection hole penetrates the boundary region. It is suitable if it is provided.

このように窒素噴射弁３４が備えられている構成においては、要求燃料噴射量Fiが上記第１要求燃料噴射量Fi1よりも大きい場合、第２成層領域の燃焼中にて窒素が噴射されるように制御される。具体的には、燃料の燃焼開始時期からの燃料の燃焼による熱発生率の積算値が、燃焼開始時期から燃料の燃焼終了時期までの熱発生率の積算値の９０％に達する時期にて、窒素が噴射されるように、窒素噴射弁３４に噴射指令がなされる。本例では、上記９０％に達する時期は、同時期を適合する実験結果に基づいて作製された同時期、要求燃料噴射量Fi、及び点火時期との関係を規定するテーブルに基づいて決定される。   In the configuration including the nitrogen injection valve 34 as described above, when the required fuel injection amount Fi is larger than the first required fuel injection amount Fi1, nitrogen is injected during combustion in the second stratified region. Controlled. Specifically, at a time when the integrated value of the heat generation rate due to the combustion of the fuel from the combustion start timing of the fuel reaches 90% of the integrated value of the heat generation rate from the combustion start timing to the combustion end timing of the fuel, An injection command is issued to the nitrogen injection valve 34 so that nitrogen is injected. In this example, the timing of reaching 90% is determined based on a table that defines the relationship between the simultaneous period, the required fuel injection amount Fi, and the ignition timing, which are produced based on the experimental results that match the simultaneous period. .

これにより、図５（Ｂ）に示すように、窒素が噴射されることで、窒素が第２成層領域外の酸素を巻き込んで第２成層領域内へ向かって流動する。これにより、平均空燃比のリッチ度合いの大きい第２成層領域の燃焼の際に発生する未燃ＨＣ，ＣＯと上記酸素とが混合し得る。そして、上記未燃ＨＣ，ＣＯが酸化（燃焼）する。   As a result, as shown in FIG. 5B, when nitrogen is injected, the nitrogen flows into the second stratification region by entraining oxygen outside the second stratification region. As a result, unburned HC, CO generated during combustion in the second stratified region where the richness of the average air-fuel ratio is large can be mixed with the oxygen. The unburned HC and CO are oxidized (burned).

図６は、上述のように窒素が噴射された場合における、熱発生率の変化の一例を示したタイムチャートである。窒素の噴射時期以降、上述のように未燃ＨＣ，ＣＯが燃焼することにより、熱発生率が一時的に増大する。従って、窒素が噴射されない構成（図６の破線を参照）に比して、燃費を向上させることができる。   FIG. 6 is a time chart showing an example of a change in the heat generation rate when nitrogen is injected as described above. Since the unburned HC and CO are burned as described above after the nitrogen injection timing, the heat generation rate temporarily increases. Therefore, fuel consumption can be improved compared to a configuration in which nitrogen is not injected (see the broken line in FIG. 6).

なお、本変形例では、不活性ガスとしての窒素を噴射しているが、これに代えて、アルゴン等の希ガス、二酸化炭素等を噴射してもよい。   In this modification, nitrogen as an inert gas is injected, but instead of this, a rare gas such as argon, carbon dioxide, or the like may be injected.

（第２実施形態）
次に、本発明の第２実施形態に係る内燃機関の制御装置について説明する。第２実施形態の制御装置は、以下の２点においてのみ上記第１実施形態のものと異なる。 (Second Embodiment)
Next, an internal combustion engine control apparatus according to a second embodiment of the present invention will be described. The control device of the second embodiment differs from that of the first embodiment only in the following two points.

第１に、図２（Ａ）に対応する図７（Ａ）に示すように、第２実施形態の制御装置が適用される内燃機関の筒内噴射弁３３は、予混合領域と成層領域との境界領域に向けて燃料を噴射するように配置されている。より具体的には、筒内噴射弁３３には、噴孔からの燃料の噴射方向の延長線が境界領域を貫通するような噴孔が少なくとも１つ備えられている。   First, as shown in FIG. 7A corresponding to FIG. 2A, the in-cylinder injection valve 33 of the internal combustion engine to which the control device of the second embodiment is applied includes a premixing region, a stratification region, It arrange | positions so that a fuel may be injected toward the boundary area | region. More specifically, the in-cylinder injection valve 33 is provided with at least one injection hole such that an extension line in the fuel injection direction from the injection hole passes through the boundary region.

第２に、この装置は、要求燃料噴射量Fiが上記第１要求燃料噴射量Fi1よりも大きい場合、成層領域を形成するための第２燃料量を、第３燃料量と第４燃料量の２つに分割して、上記配置された筒内噴射弁３３から、第３及び第４燃料量の燃料を噴射するよう制御する。以下、これらの第１実施形態と異なる点についてのみ説明する。   Secondly, when the required fuel injection amount Fi is larger than the first required fuel injection amount Fi1, the apparatus determines the second fuel amount for forming the stratified region as the third fuel amount and the fourth fuel amount. Dividing into two, the third and fourth fuel amounts are controlled to be injected from the in-cylinder injection valve 33 arranged as described above. Only the differences from the first embodiment will be described below.

この装置では、要求燃料噴射量Fiと、図８に示した要求燃料噴射量Fiと同要求燃料噴射量Fiに対する上記第１、第２、第３及び第４燃料量の割合との関係を規定するテーブルとに基づいて、上記要求燃料噴射量Fiに対する第１、第２、第３及び第４燃料量の割合が設定される。これは、第４燃料量の燃料噴射に基づいて発生する、未燃ＨＣ，ＣＯの量を抑制する観点に基づく。   In this apparatus, the relationship between the required fuel injection amount Fi and the ratios of the first, second, third and fourth fuel amounts to the required fuel injection amount Fi and the required fuel injection amount Fi shown in FIG. The ratio of the first, second, third, and fourth fuel amounts to the required fuel injection amount Fi is set based on the table to be executed. This is based on the viewpoint of suppressing the amount of unburned HC and CO generated based on the fuel injection of the fourth fuel amount.

先ず、要求燃料噴射量Fiが上記第１要求燃料噴射量Fi1よりも大きく、上記第２要求燃料噴射量Fi2以下である場合について説明する。この場合、図８に示したテーブルに基づいて、要求燃料噴射量Fiに対する第３燃料量の割合が９％に設定され、要求燃料噴射量Fiに対する第４燃料量の割合が１％に設定される。なお、要求燃料噴射量Fiに対する第１燃料量の割合は９０％に設定される。   First, a case where the required fuel injection amount Fi is larger than the first required fuel injection amount Fi1 and not more than the second required fuel injection amount Fi2 will be described. In this case, based on the table shown in FIG. 8, the ratio of the third fuel amount to the required fuel injection amount Fi is set to 9%, and the ratio of the fourth fuel amount to the required fuel injection amount Fi is set to 1%. The The ratio of the first fuel amount to the required fuel injection amount Fi is set to 90%.

図９は、要求燃料噴射量Fiと第２燃料量との関係を示すグラフである。この場合、要求燃料噴射量Fiが上記第１要求燃料噴射量Fi1から増大していくと、第３及び４燃料量は、９：１の一定の割合を維持しながら増大していくようになっている。   FIG. 9 is a graph showing the relationship between the required fuel injection amount Fi and the second fuel amount. In this case, as the required fuel injection amount Fi increases from the first required fuel injection amount Fi1, the third and fourth fuel amounts increase while maintaining a constant ratio of 9: 1. ing.

図７の左側に示したように、この場合、この装置では、要求燃料噴射量Fiが上記第１要求燃料噴射量Fi1以下における場合と同様の予混合領域が形成される。その後、圧縮行程後半の（点火時期より前の）所定の時期（第３燃料噴射時期）にて、筒内噴射弁３３から上記設定された第３燃料量の燃料が燃焼室２３内（即ち、予混合領域内）に噴射される。   As shown on the left side of FIG. 7, in this case, in this apparatus, a premixing region similar to the case where the required fuel injection amount Fi is equal to or less than the first required fuel injection amount Fi1 is formed. Thereafter, at a predetermined timing (third fuel injection timing) in the latter half of the compression stroke (third fuel injection timing), the third amount of fuel set from the in-cylinder injection valve 33 is injected into the combustion chamber 23 (that is, Injected into the premixing zone).

これにより、予混合領域内であって点火プラグ３１の周りに、燃料の濃度が略均一な混合気の成層領域が形成される。この成層領域は、平均空燃比が理論空燃比よりもリッチとなるように、且つ、一定の体積Ｖ１をもつように形成される。このため、上記予混合領域と上記成層領域との境界領域が形成される。この境界領域には、上記ＮＯｘ発生範囲内の空燃比をもった混合気が存在する。   Thereby, a stratified region of the air-fuel mixture having a substantially uniform fuel concentration is formed in the premixed region and around the spark plug 31. This stratified region is formed so that the average air-fuel ratio is richer than the stoichiometric air-fuel ratio and has a constant volume V1. For this reason, a boundary region between the premixed region and the stratified region is formed. In this boundary region, there is an air-fuel mixture having an air-fuel ratio within the NOx generation range.

そして、図７の右側に示したように、第３燃料量の燃料噴射時期よりも後であって、点火時期直前の時期（第４燃料噴射時期）にて、筒内噴射弁３３から上記設定された第４燃料量の燃料が、上記境界領域に向けて噴射される。   Then, as shown on the right side of FIG. 7, the above-mentioned setting is made from the in-cylinder injection valve 33 at the timing (fourth fuel injection timing) after the fuel injection timing of the third fuel amount and immediately before the ignition timing. The fourth amount of fuel thus injected is injected toward the boundary region.

これにより、上記境界領域内において、混合気の空燃比のリッチ度合いが大きくなる。従って、同境界領域内において、上記ＮＯｘ発生範囲内の空燃比をもった混合気の量が小さくなり得る。この結果、要求燃料噴射量Fiが大きい場合（即ち、境界領域の温度が高い場合）であっても、第３燃料量の燃料噴射により形成される境界領域から発生するＮＯｘの量を抑制することができる。   As a result, the richness of the air-fuel ratio of the air-fuel mixture increases within the boundary region. Therefore, the amount of the air-fuel mixture having the air-fuel ratio within the NOx generation range can be reduced within the boundary region. As a result, even when the required fuel injection amount Fi is large (that is, when the temperature of the boundary region is high), the amount of NOx generated from the boundary region formed by fuel injection of the third fuel amount is suppressed. Can do.

また、第４燃料量の燃料噴射によっても混合気の成層領域が形成される。即ち、同成層領域と予混合領域との境界領域が形成される。ここで、同境界領域においては、第４燃料量の燃料噴射時期から所定期間経過後に、上記ＮＯｘ発生範囲内の空燃比をもった混合気が形成される。   A stratified region of the air-fuel mixture is also formed by fuel injection of the fourth fuel amount. That is, a boundary region between the stratified region and the premixed region is formed. Here, in the boundary region, an air-fuel mixture having an air-fuel ratio within the NOx generation range is formed after a predetermined period has elapsed from the fuel injection timing of the fourth fuel amount.

本例では、点火時期直前に第４燃料量の燃料が噴射されるため、同境界領域にて上記ＮＯｘ発生範囲内の空燃比をもった混合気が形成される前に、点火が行われる。従って、第４燃料量の燃料噴射により形成される境界領域から発生するＮＯｘの量を抑制することができる。以上のことから、上記第１実施形態と同様、要求燃料噴射量Fiが第１要求燃料噴射量Fiよりも大きい場合であっても、ＮＯｘの発生量が上記適正範囲を超えることを防止することができる。   In this example, since the fourth fuel amount is injected immediately before the ignition timing, ignition is performed before an air-fuel mixture having an air-fuel ratio within the NOx generation range is formed in the boundary region. Therefore, the amount of NOx generated from the boundary region formed by the fuel injection of the fourth fuel amount can be suppressed. From the above, as in the first embodiment, even when the required fuel injection amount Fi is larger than the first required fuel injection amount Fi, the amount of NOx generated is prevented from exceeding the appropriate range. Can do.

次に、要求燃料噴射量Fiが上記第２要求燃料噴射量Fi2よりも大きい場合について説明する。この場合、図８に示したテーブルに基づいて、要求燃料噴射量Fiが大きいほど、要求燃料噴射量Fiに対する第３燃料量の割合がより大きい割合に設定され、要求燃料噴射量Fiに対する第４燃料量の割合がより小さい割合に設定される。なお、要求燃料噴射量Fiに対する第１燃料量の割合は９０％に設定される。   Next, a case where the required fuel injection amount Fi is larger than the second required fuel injection amount Fi2 will be described. In this case, based on the table shown in FIG. 8, as the required fuel injection amount Fi is larger, the ratio of the third fuel amount to the required fuel injection amount Fi is set to a larger ratio. The ratio of the fuel amount is set to a smaller ratio. The ratio of the first fuel amount to the required fuel injection amount Fi is set to 90%.

これは、以下の観点に基づく。第４燃料量が大きいほど、第４燃料量の噴射により形成される混合気の成層領域の平均空燃比のリッチ度合いがより大きくなって、同成層領域からの未燃ＨＣ，ＣＯの発生量がより大きくなる傾向がある。要求燃料噴射量Fiが大きい場合であっても、第４燃料量が小さい量に設定されれば、上記未燃ＨＣ，ＣＯの発生量が抑制され得る。   This is based on the following viewpoint. As the fourth fuel amount increases, the richness of the average air-fuel ratio in the stratified region of the air-fuel mixture formed by the injection of the fourth fuel amount increases, and the amount of unburned HC and CO generated from the stratified region decreases. There is a tendency to become larger. Even when the required fuel injection amount Fi is large, if the fourth fuel amount is set to a small amount, the generation amount of the unburned HC and CO can be suppressed.

図９に示すように、この場合、第３燃料量が、要求燃料噴射量Fiの１０％の量から、第２要求燃料噴射量Fi2の１％の量を減じた量に設定され、第４燃料量が、第２要求燃料噴射量Fi2の１％と等しい量に設定される。要求燃料噴射量Fiが第２要求燃料噴射量Fi2から増大していくと、第３燃料量は増大していく一方、第４燃料量は上記第２要求燃料噴射量Fi2の１％の量に維持されるようになっている。   As shown in FIG. 9, in this case, the third fuel amount is set to an amount obtained by subtracting the amount of 1% of the second required fuel injection amount Fi2 from the amount of 10% of the required fuel injection amount Fi. The fuel amount is set to an amount equal to 1% of the second required fuel injection amount Fi2. As the required fuel injection amount Fi increases from the second required fuel injection amount Fi2, the third fuel amount increases, while the fourth fuel amount becomes 1% of the second required fuel injection amount Fi2. To be maintained.

従って、要求燃料噴射量Fiが第２要求燃料噴射量Fi2よりも大きくなる場合であっても、第４燃料量の噴射により形成される混合気の成層領域における平均空燃比が一定に維持される。   Therefore, even when the required fuel injection amount Fi is larger than the second required fuel injection amount Fi2, the average air-fuel ratio in the stratified region of the air-fuel mixture formed by the injection of the fourth fuel amount is kept constant. .

この結果、上記第１実施形態と同様、要求燃料噴射量Fiが第２要求燃料噴射量Fi2よりも大きい場合であっても、未燃ＨＣ，ＣＯの発生量が上記適正範囲を超えることを防止することができる。   As a result, similarly to the first embodiment, even when the required fuel injection amount Fi is larger than the second required fuel injection amount Fi2, the generation amount of unburned HC and CO is prevented from exceeding the appropriate range. can do.

ここで、この装置における、上記第３及び第４燃料量の燃料の噴射時期の設定方法について付言する。第３燃料量の燃料噴射により形成された境界領域内においては、第３燃料量の燃料が噴射されてから所定期間経過後に、上記ＮＯｘ発生範囲の空燃比をもった混合気が形成される。この所定期間は、一般に、第３燃料量が大きいほどより長くなると考えられる。   Here, the method for setting the fuel injection timings of the third and fourth fuel amounts in this apparatus will be additionally described. In the boundary region formed by the fuel injection of the third fuel amount, an air-fuel mixture having an air-fuel ratio in the NOx generation range is formed after a predetermined period has elapsed since the fuel injection of the third fuel amount. This predetermined period is generally considered to be longer as the third fuel amount is larger.

この境界領域において、上記ＮＯｘ発生範囲の空燃比をもつ混合気の量を確実に小さくするためには、同境界領域内に上記ＮＯｘ発生範囲の空燃比をもった混合気が形成されたときに、第４燃料量の燃料噴射がなされると好適である。従って、第３燃料量の噴射時期と第４燃料量の噴射時期との間隔は、第３燃料量が大きいほどより長くなるように、第３及び第４燃料量の噴射時期が設定されることが好適である。   In order to reliably reduce the amount of the air-fuel mixture having the air-fuel ratio in the NOx generation range in the boundary region, when the air-fuel mixture having the air-fuel ratio in the NOx generation range is formed in the boundary region. It is preferable that the fourth fuel amount is injected. Therefore, the injection timings of the third and fourth fuel amounts are set so that the interval between the injection timing of the third fuel amount and the injection timing of the fourth fuel amount becomes longer as the third fuel amount becomes larger. Is preferred.

上記観点から、この装置では、図１０に示しめした第３燃料量の燃料噴射時期と第４燃料量の燃料噴射時期との間隔に対応するクランク角度差Θと、第３燃料量との関係を規定するテーブルに基づいて、上記クランク角度差Θが設定される。このテーブルにより、第３燃料量が大きいほど、上記クランク角度差Θがより大きい値に設定される。そして、上記設定されたクランク角度差Θに基づいて、第３及び第４燃料量の燃料噴射時期が設定されるようになっている。これにより、上記境界領域から発生するＮＯｘの量を確実に抑制することができる。   From the above viewpoint, in this apparatus, the relationship between the third fuel amount and the crank angle difference Θ corresponding to the interval between the fuel injection timing of the third fuel amount and the fuel injection timing of the fourth fuel amount shown in FIG. The crank angle difference Θ is set based on a table that defines According to this table, the larger the third fuel amount, the larger the crank angle difference Θ is set. The fuel injection timings for the third and fourth fuel amounts are set based on the set crank angle difference Θ. Thereby, the amount of NOx generated from the boundary region can be reliably suppressed.

以上、説明したように、本発明の第２実施形態によれば、要求燃料噴射量Fiが上記第１要求燃料噴射量Fi1よりも大きい場合、先ず、第２燃料量の一部である第３燃料量が噴射されて、成層領域が、第１燃料量の燃料噴射により形成された予混合領域内に形成される。その後、第２燃料量の残りの部分である第４燃料量が、予混合領域と成層領域との境界領域に向けて噴射されるように燃料の噴射形態が制御される。   As described above, according to the second embodiment of the present invention, when the required fuel injection amount Fi is larger than the first required fuel injection amount Fi1, first, the third fuel amount that is a part of the second fuel amount. The fuel amount is injected, and the stratification region is formed in the premixing region formed by the fuel injection of the first fuel amount. Thereafter, the fuel injection mode is controlled so that the fourth fuel amount, which is the remaining portion of the second fuel amount, is injected toward the boundary region between the premix region and the stratification region.

これにより、第３燃料量の燃料噴射により形成される境界領域において、混合気の空燃比のリッチ度合いが大きくなり、上記ＮＯｘ発生範囲内の空燃比をもった混合気の量が小さくなり得る。この結果、第３燃料量の燃料噴射により形成される境界領域から発生するＮＯｘの量を抑制することができる。また、第４燃料量の燃料噴射時期は点火時期直前である。従って、第４燃料量の燃料噴射により形成される境界領域において、上記ＮＯｘ発生範囲内の空燃比をもった混合気が形成される前に、混合気が燃焼し得る。以上のことから、要求燃料噴射量Fiが大きい場合であっても、内燃機関１０において発生するＮＯｘの量を抑制することができる。   Thereby, in the boundary region formed by fuel injection of the third fuel amount, the richness of the air-fuel ratio of the air-fuel mixture increases, and the amount of air-fuel mixture having the air-fuel ratio within the NOx generation range can be reduced. As a result, the amount of NOx generated from the boundary region formed by the fuel injection of the third fuel amount can be suppressed. The fuel injection timing for the fourth fuel amount is immediately before the ignition timing. Therefore, in the boundary region formed by the fuel injection of the fourth fuel amount, the air-fuel mixture can burn before the air-fuel mixture having the air-fuel ratio within the NOx generation range is formed. From the above, even when the required fuel injection amount Fi is large, the amount of NOx generated in the internal combustion engine 10 can be suppressed.

本発明は、上記各実施形態に限定されることはなく、本発明の範囲内において種々の変形例を採用することができる。例えば、上記各実施形態においては、内燃機関１０がポート噴射弁３２を備え、ポート噴射弁３２が第１燃料量の燃料を噴射するようになっているが、これに代えて、内燃機関１０がポート噴射弁を備えないよう構成され、筒内噴射弁３３が第１燃料量の燃料を噴射するようにしてもよい。   The present invention is not limited to the above embodiments, and various modifications can be employed within the scope of the present invention. For example, in each of the above embodiments, the internal combustion engine 10 includes the port injection valve 32, and the port injection valve 32 injects the first fuel amount of fuel. The in-cylinder injection valve 33 may be configured not to include a port injection valve, and may inject the first fuel amount of fuel.

また、上記各実施形態においては、第２要求燃料噴射量Fi2が、第１要求燃料噴射量Fi1よりも大きい量に設定されているが、これに代えて、第２要求燃料噴射量Fi2が、第１要求燃料噴射量Fi1と等しい量に設定されてもよい。   In each of the above embodiments, the second required fuel injection amount Fi2 is set to be larger than the first required fuel injection amount Fi1, but instead, the second required fuel injection amount Fi2 is The amount may be set equal to the first required fuel injection amount Fi1.

なお、上記第１実施形態においては、第２成層領域における平均空燃比が理論空燃比よりもリッチとなるように第２成層領域が形成されているが、これに代えて、成層領域における平均空燃比が理論空燃比より若干リーン（具体的には、１５．４〜１５．６の範囲内）となるように、成層領域を形成することも考えられる。   In the first embodiment, the second stratification region is formed so that the average air-fuel ratio in the second stratification region is richer than the stoichiometric air-fuel ratio. Instead, the average air-fuel ratio in the stratification region is changed. It is also conceivable to form the stratification region so that the fuel ratio is slightly leaner than the stoichiometric air-fuel ratio (specifically, within the range of 15.4 to 15.6).

種々の実験等により、混合気の空燃比が１５．６よりも大きくなると、混合気の燃焼により発生するＮＯｘの量が大きくなる傾向が顕著になる一方、混合気の空燃比が１５．４よりも小さくなると、混合気の燃焼により発生する未燃ＨＣ，ＣＯの量が大きくなる傾向が顕著になることが知られている。第２成層領域における平均空燃比が１５．４〜１５．６の範囲内とされれば、ＮＯｘの発生量、及び未燃ＨＣ，ＣＯの発生量を抑制することができる。上記構成は係る知見に基づく。これによれば、第２成層領域の平均空燃比が理論空燃比よりもリッチな場合に比して、燃費を向上させることができる。   According to various experiments and the like, when the air-fuel ratio of the air-fuel mixture becomes larger than 15.6, the amount of NOx generated by the combustion of the air-fuel mixture becomes prominent, while the air-fuel ratio of the air-fuel mixture becomes more than 15.4. It is known that if the value is smaller, the amount of unburned HC and CO generated by the combustion of the air-fuel mixture tends to increase. If the average air-fuel ratio in the second stratification region is in the range of 15.4 to 15.6, the amount of NOx generated and the amount of unburned HC and CO generated can be suppressed. The above configuration is based on such knowledge. According to this, the fuel efficiency can be improved as compared with the case where the average air-fuel ratio in the second stratified region is richer than the stoichiometric air-fuel ratio.

本発明の第１実施形態に係る制御装置が適用される内燃機関の概略構成図である。1 is a schematic configuration diagram of an internal combustion engine to which a control device according to a first embodiment of the present invention is applied. 図１に示した内燃機関の燃焼室内に形成される、混合気の予混合領域及び混合気の成層領域を模式的に示した図である。FIG. 2 is a view schematically showing a premixed region of an air-fuel mixture and a stratified region of the air-fuel mixture formed in the combustion chamber of the internal combustion engine shown in FIG. 1. 本発明の第１実施形態に係る制御装置が参照する、要求燃料噴射量と、要求燃料噴射量に対する第１及び第２燃料量の割合と、の関係を規定するテーブルを示した図である。It is the figure which showed the table which prescribes | regulates the relationship between the request | requirement fuel injection amount and the ratio of the 1st and 2nd fuel amount with respect to a request | requirement fuel injection amount which the control apparatus which concerns on 1st Embodiment of this invention refers. 本発明の第１実施形態に係る制御装置による制御が実行された場合における、要求燃料噴射量と第２燃料量との関係を示したグラフである。It is the graph which showed the relationship between the request | requirement fuel injection amount and the 2nd fuel amount in case the control by the control apparatus which concerns on 1st Embodiment of this invention is performed. 本発明の第１実施形態の変形例に係る制御装置が適用される内燃機関の燃焼室内に、不活性ガスである窒素が噴射される様子を模式的に示した図である。It is the figure which showed typically a mode that nitrogen which is inert gas was injected in the combustion chamber of the internal combustion engine to which the control apparatus which concerns on the modification of 1st Embodiment of this invention is applied. 本発明の第１実施形態の変形例に係る制御装置による制御が実行された場合における、燃料の燃焼による熱発生率の変化の一例を示したタイムチャートである。It is the time chart which showed an example of the change of the heat release rate by the combustion of a fuel in case the control by the control apparatus which concerns on the modification of 1st Embodiment of this invention is performed. 本発明の第２実施形態に係る制御装置が適用される内燃機関の燃焼室内に形成される、混合気の予混合領域及び混合気の成層領域を模式的に示した図である。It is the figure which showed typically the pre-mixing area | region of the air-fuel | gaseous mixture formed in the combustion chamber of the internal combustion engine to which the control apparatus which concerns on 2nd Embodiment of this invention is applied, and the stratification area | region of air-fuel | gaseous mixture. 本発明の第２実施形態に係る制御装置が参照する、要求燃料噴射量と、要求燃料噴射量に対する第１、第２、第３及び第４燃料量の割合と、の関係を規定するテーブルを示した図である。The table which prescribes | regulates the relationship between the request | requirement fuel-injection amount and the ratio of the 1st, 2nd, 3rd and 4th fuel amount with respect to a request | requirement fuel injection amount which the control apparatus which concerns on 2nd Embodiment of this invention refers. FIG. 本発明の第２実施形態に係る制御装置による制御が実行された場合における、要求燃料噴射量と第２燃料量との関係を示したグラフである。It is the graph which showed the relationship between the request | requirement fuel injection amount and the 2nd fuel amount in case the control by the control apparatus which concerns on 2nd Embodiment of this invention is performed. 第３燃料量と、第３燃料量の燃料噴射時期と第４燃料量の燃料噴射時期との間隔に対応するクランク角度差と、の関係を規定するテーブルを示した図である。It is the figure which prescribed | regulated the table which prescribes | regulates the relationship between the 3rd fuel amount, and the crank angle difference corresponding to the space | interval of the fuel injection timing of the 3rd fuel amount, and the fuel injection timing of the 4th fuel amount. ＨＣＣＩ燃焼を実行する内燃機関の燃焼室内に形成される、混合気の予混合領域及び混合気の成層領域の一例を模式的に示した図である。It is the figure which showed typically an example of the pre-mixing area | region of the air-fuel | gaseous mixture formed in the combustion chamber of the internal combustion engine which performs HCCI combustion, and the stratification area | region of air-fuel | gaseous mixture. 一般的な燃料の混合気における空燃比及び温度と、ＮＯｘ発生量との関係を示したグラフである。It is the graph which showed the relationship between the air fuel ratio and temperature in the common fuel-air mixture, and NOx generation amount.

符号の説明Explanation of symbols

１０…内燃機関、２３…燃焼室、３１…点火プラグ、３２…ポート噴射弁、３３…筒内噴射弁、３４…窒素噴射弁   DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 23 ... Combustion chamber, 31 ... Spark plug, 32 ... Port injection valve, 33 ... In-cylinder injection valve, 34 ... Nitrogen injection valve

Claims (8)

内燃機関の燃焼室内にて燃料を直接噴射する筒内噴射弁、又は、前記筒内噴射弁及び内燃機関の吸気通路に燃料を噴射するポート噴射弁と、
点火プラグと、
を備えた内燃機関に適用され、
前記内燃機関の運転状態に基づいて要求燃料噴射量を決定する要求燃料噴射量決定手段と、
第１燃料噴射時期にて、前記筒内噴射弁、又は前記ポート噴射弁から前記決定された要求燃料噴射量の半分よりも大きい第１燃料量の燃料を噴射して、混合気の予混合領域を形成し、
前記第１燃料噴射時期よりも後の第２燃料噴射時期にて、前記筒内噴射弁から前記要求燃料噴射量から前記第１燃料量を除いた残りの量である第２燃料量の燃料を噴射して、前記予混合領域内であって前記点火プラグの周りに混合気の第１成層領域を形成する噴射形態制御手段と、
前記第２燃料噴射時期よりも後にて、前記点火プラグにて点火を行う点火制御手段と、
を備えた内燃機関の制御装置において、
前記噴射形態制御手段は、
前記要求燃料噴射量に基づく前記内燃機関の負荷を表す値が第１所定値よりも大きい場合、前記第１燃料量をゼロに、前記第２燃料量を前記要求燃料噴射量と等しい量に設定して、前記燃焼室内に吸入されたガス中に、前記第１成層領域よりも体積が大きい混合気の第２成層領域であって前記第２燃料量に対する前記第２成層領域中に含まれる空気量の割合が理論空燃比よりもリッチな第２成層領域を形成するように構成された内燃機関の制御装置。 An in-cylinder injection valve that directly injects fuel in the combustion chamber of the internal combustion engine, or a port injection valve that injects fuel into the in-cylinder injection valve and the intake passage of the internal combustion engine;
Spark plugs,
Applied to an internal combustion engine with
Required fuel injection amount determining means for determining a required fuel injection amount based on an operating state of the internal combustion engine;
At the first fuel injection timing, a fuel of a first fuel amount larger than half of the determined required fuel injection amount is injected from the in-cylinder injection valve or the port injection valve, and a premixing region of the air-fuel mixture Form the
At a second fuel injection timing after the first fuel injection timing, a second fuel amount of fuel, which is the remaining amount obtained by subtracting the first fuel amount from the required fuel injection amount from the in-cylinder injection valve, Injection mode control means for injecting and forming a first stratification region of the air-fuel mixture within the premixing region and around the spark plug;
Ignition control means for igniting with the spark plug after the second fuel injection timing;
An internal combustion engine control apparatus comprising:
The injection form control means includes
If the value representing the load of the internal combustion engine based on the required fuel injection amount is greater than a first predetermined value, the first fuel amount is set to zero, and the second fuel amount is set equal to the required fuel injection amount. Then, in the gas sucked into the combustion chamber, the air contained in the second stratification region of the air-fuel mixture having a volume larger than that of the first stratification region and corresponding to the second fuel amount. A control device for an internal combustion engine configured to form a second stratification region in which a ratio of the amount is richer than a stoichiometric air-fuel ratio. 請求項１に記載の内燃機関の制御装置において、
前記噴射形態制御手段は、
前記負荷を表す値が前記第１所定値以上の第２所定値よりも大きい場合、前記第１燃料量をゼロでない所定量に、前記第２燃料量を前記要求燃料噴射量よりも前記所定量だけ小さい量に設定して、前記予混合領域内に前記第２成層領域を形成するように構成された内燃機関の制御装置。 The control apparatus for an internal combustion engine according to claim 1,
The injection form control means includes
When the value representing the load is greater than a second predetermined value that is equal to or greater than the first predetermined value, the first fuel amount is set to a predetermined amount that is not zero, and the second fuel amount is set to the predetermined amount from the required fuel injection amount. A control apparatus for an internal combustion engine configured to form the second stratification region in the premixing region by setting the amount to a small amount. 請求項２に記載の内燃機関の制御装置において、
前記噴射形態制御手段は、
前記負荷を表す値が前記第２所定値よりも大きい場合、前記負荷を表す値と前記第２所定値との相違の程度が大きいほど前記所定量が大きくなるように、前記第１及び第２燃料量を設定するよう構成された内燃機関の制御装置。 The control apparatus for an internal combustion engine according to claim 2,
The injection form control means includes
When the value representing the load is greater than the second predetermined value, the first and second values are such that the predetermined amount increases as the degree of difference between the value representing the load and the second predetermined value increases. A control device for an internal combustion engine configured to set a fuel amount. 請求項１乃至請求項３の何れか一項に記載の内燃機関の制御装置であって、
前記内燃機関は、
前記燃焼室内に不活性ガスを噴射する不活性ガス噴射弁を備え、
前記負荷を表す値が前記第１所定値よりも大きい場合、前記第２成層領域内の混合気の燃焼中にて、前記不活性ガス噴射弁から前記不活性ガスを噴射する不活性ガス噴射制御手段を備えた内燃機関の制御装置。 A control device for an internal combustion engine according to any one of claims 1 to 3,
The internal combustion engine
An inert gas injection valve for injecting an inert gas into the combustion chamber;
Inert gas injection control for injecting the inert gas from the inert gas injection valve during combustion of the air-fuel mixture in the second stratified region when the value representing the load is greater than the first predetermined value Control device for internal combustion engine comprising means. 請求項４に記載の内燃機関の制御装置において、
前記不活性ガス噴射制御手段は、
前記内燃機関の運転状態と、燃料の燃焼開始時期からの燃料の燃焼による熱発生率の積算値が前記燃焼開始時期から燃料の燃焼終了時期までの熱発生率の積算値の９０％に達する時期と、の関係を規定するデータを記憶するデータ記憶手段を備え、
前記内燃機関の運転状態と、前記データとに基づいて得られる前記熱発生率の積算値の９０％に達する時期にて、前記不活性ガスを噴射するように構成された内燃機関の制御装置。 The control apparatus for an internal combustion engine according to claim 4,
The inert gas injection control means includes
The operating state of the internal combustion engine and the timing at which the integrated value of the heat generation rate due to fuel combustion from the fuel combustion start timing reaches 90% of the integrated value of the heat generation rate from the combustion start timing to the fuel combustion end timing And data storage means for storing data defining the relationship between
A control device for an internal combustion engine configured to inject the inert gas at a time when 90% of an integrated value of the heat generation rate obtained based on an operation state of the internal combustion engine and the data is reached. 内燃機関の燃焼室内にて燃料を直接噴射する筒内噴射弁、又は、前記筒内噴射弁及び内燃機関の吸気通路に燃料を噴射するポート噴射弁と、
点火プラグと、
を備えた内燃機関に適用され、
前記内燃機関の運転状態に基づいて要求燃料噴射量を決定する要求燃料噴射量決定手段と、
第１燃料噴射時期にて、前記筒内噴射弁、又は前記ポート噴射弁から前記決定された要求燃料噴射量の半分よりも大きい第１燃料量の燃料を噴射して、混合気の予混合領域を形成し、
前記第１燃料噴射時期よりも後の第２燃料噴射時期にて、前記筒内噴射弁から前記要求燃料噴射量から前記第１燃料量を除いた残りの量である第２燃料量の燃料を噴射して、前記予混合領域内であって前記点火プラグの周りに混合気の成層領域を形成する噴射形態制御手段と、
前記第２燃料噴射時期よりも後にて、前記点火プラグにて点火を行う点火制御手段と、
を備え、
前記筒内噴射弁は、
前記予混合領域と、前記成層領域との境界領域に向けて燃料を噴射するように配置されている内燃機関の制御装置において、
前記噴射形態制御手段は、
前記要求燃料噴射量に基づく前記内燃機関の負荷を表す値が第１所定値よりも大きい場合、前記点火を行う時期よりも前の第３燃料噴射時期にて、前記第２燃料量の一部である第３燃料量の燃料を噴射して、前記成層領域と体積が等しい混合気の成層領域を形成し、前記第３燃料噴射時期よりも後であって前記点火を行う時期よりも前の第４燃料噴射時期にて、前記第２燃料量から前記第３燃料量を除いた残りの量である第４燃料量の燃料を噴射するように構成された内燃機関の制御装置。 An in-cylinder injection valve that directly injects fuel in the combustion chamber of the internal combustion engine, or a port injection valve that injects fuel into the in-cylinder injection valve and the intake passage of the internal combustion engine;
Spark plugs,
Applied to an internal combustion engine with
Required fuel injection amount determining means for determining a required fuel injection amount based on an operating state of the internal combustion engine;
At the first fuel injection timing, a fuel of a first fuel amount larger than half of the determined required fuel injection amount is injected from the in-cylinder injection valve or the port injection valve, and a premixing region of the air-fuel mixture Form the
At a second fuel injection timing after the first fuel injection timing, a second fuel amount of fuel, which is the remaining amount obtained by subtracting the first fuel amount from the required fuel injection amount from the in-cylinder injection valve, Injection mode control means for injecting and forming a stratified region of the air-fuel mixture within the premixing region and around the spark plug;
Ignition control means for igniting with the spark plug after the second fuel injection timing;
With
The in-cylinder injection valve is
In the control device for an internal combustion engine arranged to inject fuel toward the boundary region between the premixing region and the stratification region,
The injection form control means includes
When a value representing the load of the internal combustion engine based on the required fuel injection amount is greater than a first predetermined value, a part of the second fuel amount at a third fuel injection timing prior to the ignition timing. A fuel of a third fuel amount is injected to form a stratified region of an air-fuel mixture having the same volume as the stratified region, and is after the third fuel injection timing and before the ignition timing. A control device for an internal combustion engine configured to inject a fuel of a fourth fuel amount that is a remaining amount obtained by subtracting the third fuel amount from the second fuel amount at a fourth fuel injection timing. 請求項６に記載の内燃機関の制御装置において、
前記噴射形態制御手段は、
前記負荷を表す値が前記第１所定値以上の第２所定値よりも大きい場合、前記負荷を表す値と前記第２所定値との相違の程度が大きいほど前記第３燃料量が大きくなるように、前記第３及び第４燃料量を設定するよう構成された内燃機関の制御装置。 The control apparatus for an internal combustion engine according to claim 6,
The injection form control means includes
When the value representing the load is greater than a second predetermined value equal to or greater than the first predetermined value, the third fuel amount increases as the degree of difference between the value representing the load and the second predetermined value increases. And a control device for an internal combustion engine configured to set the third and fourth fuel amounts. 請求項６又は請求項７に記載の内燃機関の制御装置において、
前記噴射形態制御手段は、
前記第３燃料量が大きいほど、前記第３燃料噴射時期と前記第４燃料噴射時期との間隔が大きくなるように、前記第３及び第４燃料噴射時期を設定するよう構成された内燃機関の制御装置。 The control apparatus for an internal combustion engine according to claim 6 or 7,
The injection form control means includes
An internal combustion engine configured to set the third and fourth fuel injection timings such that the larger the third fuel amount, the larger the interval between the third fuel injection timing and the fourth fuel injection timing. Control device.
JP2007245568A 2007-09-21 2007-09-21 Control device for internal combustion engine Pending JP2009074488A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010285969A (en) * 2009-06-15 2010-12-24 Nissan Motor Co Ltd Stratified charge, compression and ignition type engine and control device of engine
JP2011236792A (en) * 2010-05-10 2011-11-24 Honda Motor Co Ltd Device for control of fuel injection in internal combustion engine
JP2019039326A (en) * 2017-08-24 2019-03-14 マツダ株式会社 Control device for premixed compression ignition engine
JP2019039327A (en) * 2017-08-24 2019-03-14 マツダ株式会社 Control device for premixed compression ignition engine
JP2019039328A (en) * 2017-08-24 2019-03-14 マツダ株式会社 Control device for premixed compression ignition engine

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010285969A (en) * 2009-06-15 2010-12-24 Nissan Motor Co Ltd Stratified charge, compression and ignition type engine and control device of engine
JP2011236792A (en) * 2010-05-10 2011-11-24 Honda Motor Co Ltd Device for control of fuel injection in internal combustion engine
JP2019039326A (en) * 2017-08-24 2019-03-14 マツダ株式会社 Control device for premixed compression ignition engine
JP2019039327A (en) * 2017-08-24 2019-03-14 マツダ株式会社 Control device for premixed compression ignition engine
JP2019039328A (en) * 2017-08-24 2019-03-14 マツダ株式会社 Control device for premixed compression ignition engine

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