JP2007040218A - Control device for compression ignition internal combustion engine - Google Patents

Control device for compression ignition internal combustion engine Download PDF

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JP2007040218A
JP2007040218A JP2005226358A JP2005226358A JP2007040218A JP 2007040218 A JP2007040218 A JP 2007040218A JP 2005226358 A JP2005226358 A JP 2005226358A JP 2005226358 A JP2005226358 A JP 2005226358A JP 2007040218 A JP2007040218 A JP 2007040218A
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compression
rotation side
deterioration
engine
internal combustion
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Tomoyoshi Date
知善 伊達
Hirokimi Koyama
博公 小山
Takeshi Matsuda
健 松田
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Nissan Motor Co Ltd
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Nissan Motor Co Ltd
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    • 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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  • Combined Controls Of Internal Combustion Engines (AREA)
  • Combustion Methods Of Internal-Combustion Engines (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To cope with the deterioration of an engine compression system in an compression ignition combustion engine. <P>SOLUTION: Compression pressure on a low rotation side (at cranking) and compression pressure on a high rotation side (at decelerating fuel-cut) are each detected. When a difference between an allowance X of the drop of the compression pressure from an initial value on the low rotation side and an allowance Y of the drop of the compression pressure from an initial value on the high rotation side is a predetermined value or greater, deterioration is determined. When the deterioration is determined, a fuel injection amount is corrected to be increased so as to improve ignitability, depending on an engine speed. Otherwise, a temperature in a cylinder is increased with a negative overlap period, or spark ignition combustion is selected. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、少なくとも一部の運転領域にて圧縮着火燃焼（圧縮自己着火燃焼）を行わせる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 that performs compression ignition combustion (compression self-ignition combustion) in at least a part of the operation region.

特許文献１には、所定の運転領域にて、リーン燃焼により優れた燃費及び排気組成が得られる圧縮着火燃焼を行わせ、他の運転領域にて、高出力が得られる火花点火燃焼を行わせるようにした内燃機関が記載されている。
尚、特許文献１に記載の内燃機関では、圧縮着火燃焼から火花点火燃焼へ切換えるときに、吸気絞りや圧縮比低下により機関の筒内温度を低下させることで、円滑に切換えることができるようにしており、温度低下の時間的遅れの間は、燃料リッチ化により燃焼性を良好に維持している。
特開２００３−１８４６０６号公報 In Patent Document 1, compression ignition combustion that provides excellent fuel efficiency and exhaust composition by lean combustion is performed in a predetermined operation region, and spark ignition combustion that provides high output is performed in another operation region. An internal combustion engine is described.
In the internal combustion engine described in Patent Document 1, when switching from compression ignition combustion to spark ignition combustion, the temperature in the cylinder of the engine is decreased by reducing the intake throttle or the compression ratio so that the engine can be switched smoothly. In addition, during the time delay of the temperature drop, the combustibility is well maintained by fuel enrichment.
JP 2003-184606 A

上記のように圧縮着火燃焼を行わせる内燃機関では、機関の圧縮系の劣化、例えばピストンリングの張力低下やシリンダボアの削れ等を生じると、圧縮圧力の低下により、着火性が悪化し、特に低回転側で影響が顕著となる。
従って、機関の圧縮系の劣化を的確に検出し、対策を講じる必要がある。これが本発明の課題である。 In an internal combustion engine that performs compression ignition combustion as described above, if deterioration of the compression system of the engine, for example, lowering of the tension of the piston ring or scraping of the cylinder bore occurs, the ignitability deteriorates due to the reduction of the compression pressure, particularly low. The effect becomes significant on the rotation side.
Therefore, it is necessary to accurately detect deterioration of the compression system of the engine and take measures. This is the subject of the present invention.

本発明では、低回転側での圧縮圧力と高回転側での圧縮圧力とに基づいて、機関の圧縮系の劣化を判定し、劣化と判定されたときに、機関回転数に応じて、機関の着火性を改善するように制御する構成とする。   In the present invention, the deterioration of the compression system of the engine is determined based on the compression pressure on the low rotation side and the compression pressure on the high rotation side, and when the deterioration is determined, The structure is controlled so as to improve the ignitability.

本発明によれば、機関の圧縮系の劣化による圧縮圧力の低下は低回転側ほど大きく、高回転側ほど小さいことから、低回転側での圧縮圧力と高回転側での圧縮圧力とに基づいて、劣化を的確に検出することができ、また、低回転側ほど圧縮圧力の低下により着火性が悪化するので、劣化と判定されたときに、機関回転数に応じて、機関の着火性を改善するように制御することにより、的確に対策できる。   According to the present invention, the decrease in the compression pressure due to the deterioration of the compression system of the engine is larger on the low rotation side and smaller on the high rotation side, and therefore is based on the compression pressure on the low rotation side and the compression pressure on the high rotation side. Therefore, the deterioration can be accurately detected, and the lower the rotation speed, the worse the ignitability due to the lowering of the compression pressure. By taking control to improve, it is possible to take appropriate measures.

以下に本発明の実施の形態を図面に基づいて説明する。
図１は本発明の一実施形態を示す内燃機関（エンジン）のシステム図である。
シリンダヘッド１、シリンダブロック２及びピストン３によって画成される燃焼室４は、吸気弁５を介して吸気ポート６と接続され、また排気弁７を介して排気ポート８と接続されている。吸気弁５及び排気弁７の開閉時期は、それぞれ、可変動弁装置９、１０により制御可能である。 Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a system diagram of an internal combustion engine (engine) showing an embodiment of the present invention.
A combustion chamber 4 defined by the cylinder head 1, the cylinder block 2, and the piston 3 is connected to an intake port 6 through an intake valve 5 and is connected to an exhaust port 8 through an exhaust valve 7. The opening / closing timing of the intake valve 5 and the exhaust valve 7 can be controlled by the variable valve gears 9 and 10, respectively.

燃焼室４内には、燃料噴射弁１１と、点火プラグ１２とが臨んでいる。燃料噴射弁１１は吸気ポート６に配置してもよい。点火プラグ１２は火花点火燃焼用である。
燃料噴射弁１１、点火プラグ１２、可変動弁装置９、１０の作動は、エンジンコントロールユニットユニット（ＥＣＵ）１３により制御される。
ＥＣＵ１３には、クランク角センサ１４により検出されるエンジン回転数Ｎｅ、アクセル開度センサ（図示せず）により検出されるアクセル開度ＡＰＯ、エアフローメータ（図示せず）により検出される吸入空気量Ｑａの他、燃焼室４内に臨ませた筒内圧センサ１５により検出される筒内圧力Ｐｃ等の情報が入力されている。 A fuel injection valve 11 and a spark plug 12 face the combustion chamber 4. The fuel injection valve 11 may be disposed in the intake port 6. The spark plug 12 is for spark ignition combustion.
The operations of the fuel injection valve 11, the spark plug 12, and the variable valve gears 9 and 10 are controlled by an engine control unit unit (ECU) 13.
The ECU 13 includes an engine speed Ne detected by the crank angle sensor 14, an accelerator opening APO detected by an accelerator opening sensor (not shown), and an intake air amount Qa detected by an air flow meter (not shown). In addition, information such as the in-cylinder pressure Pc detected by the in-cylinder pressure sensor 15 facing the combustion chamber 4 is input.

本実施形態のエンジンでは、比較的低負荷側の所定の運転領域（図４参照）にて、必要により吸気通路に設けた吸気加熱装置（ヒータ、過給機など）により吸気温度を上昇させつつ、圧縮着火燃焼を行わせ、このとき空燃比をリーン化することで、燃費を節減する。
その一方、高負荷側やアイドル運転域など、他の運転領域では、点火プラグ１２を用いて、火花点火燃焼を行わせ、高出力やアイドル安定性を確保する。 In the engine of the present embodiment, the intake air temperature is raised by an intake air heating device (a heater, a supercharger, etc.) provided in the intake passage as necessary in a predetermined operation region (see FIG. 4) on the relatively low load side. Compressive ignition combustion is performed, and at this time, the air-fuel ratio is made lean, thereby reducing fuel consumption.
On the other hand, in other operation regions such as the high load side and the idle operation region, spark ignition combustion is performed using the spark plug 12 to ensure high output and idle stability.

ところで、エンジンの圧縮系の劣化、例えばピストンリングの張力の低下や、シリンダボアの削れ等を生じると、圧縮着火燃焼を行わせる際に、所望の圧縮圧力が得られなくなって、着火性が悪化することがある。この場合、エンジン回転数が低いときほど、圧縮圧力の低下代が大となり、圧縮着火燃焼への影響が大きくなる一方、エンジン回転数が高いときは、圧縮圧力の低下代は少なく、圧縮着火燃焼への影響も小さくなる（図５参照）。   By the way, when the compression system of the engine deteriorates, for example, when the tension of the piston ring is reduced or the cylinder bore is scraped, a desired compression pressure cannot be obtained when the compression ignition combustion is performed, and the ignitability deteriorates. Sometimes. In this case, the lower the engine speed, the greater the reduction in compression pressure and the greater the impact on compression ignition combustion. On the other hand, when the engine speed is high, there is less reduction in compression pressure and compression ignition combustion. This also reduces the effect on the environment (see FIG. 5).

そこで、本発明では、低回転側及び高回転側での圧縮圧力（モータリング筒内圧）をそれぞれ検出し、低回転側での圧縮圧力の初期値からの低下代が高回転側での圧縮圧力の初期値からの低下代に比べて大きくなったときに、エンジンの圧縮系の劣化と判定する。そして、劣化と判定されたときは、エンジン回転数に応じて、エンジンの着火性を改善するように、例えば燃料噴射量を増量補正する増量補正値を可変制御する。   Therefore, in the present invention, the compression pressure (motor ring cylinder pressure) on the low rotation side and the high rotation side is detected, respectively, and the amount of reduction from the initial value of the compression pressure on the low rotation side is the compression pressure on the high rotation side. It is determined that the compression system of the engine has deteriorated when it becomes larger than the reduction amount from the initial value. And when it determines with deterioration, according to an engine speed, the increase correction value which carries out increase correction of the fuel injection amount, for example is variably controlled so that the ignitability of an engine may be improved.

具体的な制御をフローチャートによって説明する。
図２は低回転側での圧縮圧力の低下代Ｘと高回転側での圧縮圧力の低下代Ｙとをそれぞれ算出・記憶するルーチンのフローチャートであり、所定時間毎に実行される。本ルーチンが圧縮圧力検出手段に相当する。
Ｓ１では、低回転側での圧縮圧力の検出条件（低回転かつ非燃焼の条件）として定めたクランキング時か否かを判定し、クランキング時である場合に、Ｓ２、Ｓ３の処理を実行する。 Specific control will be described with reference to a flowchart.
FIG. 2 is a flowchart of a routine for calculating and storing a compression pressure reduction margin X on the low rotation side and a compression pressure reduction margin Y on the high rotation side, which are executed at predetermined time intervals. This routine corresponds to the compression pressure detecting means.
In S1, it is determined whether or not the cranking is determined as a condition for detecting the compression pressure on the low rotation side (low rotation and non-combustion condition), and if it is during cranking, the processes of S2 and S3 are executed. To do.

Ｓ２では、筒内圧センサを用いて、クランキング時の筒内圧力（圧縮上死点近傍での値もしくはピーク値）を検出することにより、低回転側での圧縮圧力Ｐ１を検出する。
Ｓ３では、低回転側での圧縮圧力の初期値Ｐ０からの低下代Ｘ＝Ｐ０−Ｐ１を算出し（図５参照）、バックアップＲＡＭに記憶する。このとき、前回までの記憶値との加重平均をとり、これを新たな記憶値とすると、学習精度を向上させることができる。 In S2, the in-cylinder pressure at the time of cranking (a value near the compression top dead center or a peak value) is detected using an in-cylinder pressure sensor, thereby detecting the compression pressure P1 on the low rotation side.
In S3, a reduction allowance X = P0−P1 from the initial value P0 of the compression pressure on the low rotation side is calculated (see FIG. 5) and stored in the backup RAM. At this time, if a weighted average with the previous stored value is taken as a new stored value, the learning accuracy can be improved.

Ｓ４では、高回転側での圧縮圧力の検出条件（高回転かつ非燃焼の条件）として定めた減速燃料カット時か否かを判定し、減速燃料カット時である場合に、Ｓ５、Ｓ６の処理を実行する。尚、減速燃料カットは、エンジン回転数が所定の燃料カット回転数以上の状態で、アクセル開度が０になったときに行われる。
Ｓ５では、筒内圧センサを用いて、減速燃料カット時の筒内圧力（圧縮上死点近傍での値もしくはピーク値）を検出することにより、高回転側での圧縮圧力Ｐ２を検出する。 In S4, it is determined whether or not a deceleration fuel cut is set as a condition for detecting the compression pressure on the high rotation side (high rotation and non-combustion conditions). If the deceleration fuel is being cut, the processing of S5 and S6 is performed. Execute. Note that the deceleration fuel cut is performed when the accelerator opening becomes 0 in a state where the engine speed is equal to or higher than a predetermined fuel cut speed.
In S5, the in-cylinder pressure at the time of deceleration fuel cut (a value near the compression top dead center or a peak value) is detected by using the in-cylinder pressure sensor to detect the compression pressure P2 on the high rotation side.

Ｓ６では、高回転側での圧縮圧力の初期値Ｐ０からの低下代Ｙ＝Ｐ０−Ｐ２を算出し（図５参照）、バックアップＲＡＭに記憶する。このときも、前回までの記憶値との加重平均をとり、これを新たな記憶値とすると、学習精度を向上させることができる。
尚、クランキング時や減速燃料カット時に圧縮圧力を検出する際に、常にほぼ同じ基準回転数で検出するようにしてもよいし、基準回転数と実際の回転数との差に応じて、圧縮圧力を補正するようにしてもよい。 In S6, a reduction margin Y = P0-P2 from the initial value P0 of the compression pressure on the high rotation side is calculated (see FIG. 5) and stored in the backup RAM. At this time as well, the learning accuracy can be improved by taking a weighted average with the previous stored value and setting it as a new stored value.
When detecting the compression pressure at the time of cranking or at the time of deceleration fuel cut, it may be detected at almost the same reference rotation speed, or the compression may be performed according to the difference between the reference rotation speed and the actual rotation speed. The pressure may be corrected.

図３はエンジン圧縮系の劣化対応制御を含む燃焼制御ルーチンのフローチャートであり、所定時間毎に実行される。
Ｓ１１では、図４のマップを参照し、現在の運転条件（エンジン回転数Ｎｅ及び負荷；負荷としては、アクセル開度ＡＰＯ、エンジントルクなど）から、圧縮着火燃焼領域か、火花点火燃焼領域かを判定する。 FIG. 3 is a flowchart of a combustion control routine including a deterioration countermeasure control of the engine compression system, and is executed every predetermined time.
In S11, the map of FIG. 4 is referred to, and from the current operating condition (engine speed Ne and load; as the load, accelerator opening APO, engine torque, etc.), it is determined whether the compression ignition combustion region or the spark ignition combustion region. judge.

圧縮着火燃焼領域の場合は、Ｓ１２へ進み、低回転側での圧縮圧力の低下代Ｘと高回転側での圧縮圧力の低下代Ｙとを読込み、これらの差（Ｘ−Ｙ）が所定値より大きいか否かを判定する。
Ｘ−Ｙ＜所定値の場合には、エンジン圧縮系の劣化無しと判定して、Ｓ１３へ進み、通常の圧縮着火燃焼を行わせる。 In the case of the compression ignition combustion region, the process proceeds to S12, in which the compression pressure reduction margin X on the low rotation side and the compression pressure reduction margin Y on the high rotation side are read, and the difference (X−Y) is a predetermined value. Determine if greater than.
If XY <predetermined value, it is determined that the engine compression system has not deteriorated, and the routine proceeds to S13 where normal compression ignition combustion is performed.

Ｘ−Ｙ≧所定値の場合には、エンジン圧縮系の劣化有りと判定して、Ｓ１４へ進む。
図５に示されるように、エンジン圧縮系の劣化による圧縮圧力の低下は低回転側ほど大きく、高回転側ほど小さいことから、低回転側での圧縮圧力の低下代Ｘと、高回転側での圧縮圧力の低下代Ｙとに基づいて、これらの差（Ｘ−Ｙ）が所定値以上の場合は、劣化と判定できる。尚、これらの比（Ｘ／Ｙ）が所定値以上の場合に、劣化と判定するようにしてもよい。 When XY ≧ predetermined value, it is determined that the engine compression system has deteriorated, and the process proceeds to S14.
As shown in FIG. 5, the reduction of the compression pressure due to the deterioration of the engine compression system is larger at the lower rotation side and smaller at the higher rotation side. If the difference (X−Y) is greater than or equal to a predetermined value based on the reduction pressure Y of the compression pressure, it can be determined that the deterioration has occurred. Note that when these ratios (X / Y) are equal to or greater than a predetermined value, it may be determined that the deterioration has occurred.

Ｓ１４では、図６のマップを参照し、エンジン回転数Ｎｅと、劣化度合に相当する低回転側で圧縮圧力の低下代Ｘとに応じて、燃料噴射量の増量補正値（燃料増量補正値）を算出する。尚、劣化度合として、Ｘ−Ｙ、又は、Ｘ／Ｙを用いてもよい。
ここで、燃料増量補正値は、エンジン回転数Ｎｅが低いほど、劣化による圧縮圧力の低下が大となって着火性が悪化することから、着火性を改善するように、大きな値とし、また、劣化度合（低回転側での圧縮圧力の低下代Ｘ）が大きいほど、圧縮圧力の低下が大となって着火性が悪化することから、着火性を改善するように、大きな値とする。 In S14, with reference to the map of FIG. 6, the fuel injection amount increase correction value (fuel increase correction value) according to the engine speed Ne and the reduction amount X of the compression pressure on the low rotation side corresponding to the degree of deterioration. Is calculated. Note that XY or X / Y may be used as the degree of deterioration.
Here, the fuel increase correction value is set to a large value so as to improve the ignitability because the lower the engine speed Ne, the lower the compression pressure due to deterioration and the ignitability deteriorates. The greater the degree of deterioration (compression pressure reduction margin X on the low rotation side), the greater the decrease in compression pressure and the worse the ignitability. Therefore, a large value is set so as to improve the ignitability.

そして、Ｓ１５へ進み、通常の圧縮着火燃焼に比べ、前記燃料増量補正値の分、燃料噴射量を増量した上で、圧縮着火燃焼を行わせる。
図７は投入燃料と圧縮着火可能な筒内圧力との関係を示したもので、燃料噴射量の増量補正によって投入燃料を増加させることで、圧縮着火可能な筒内圧力が低下し、エンジン圧縮系の劣化の下でも、圧縮着火燃焼が可能となることがわかる。 Then, the process proceeds to S15, and the compression ignition combustion is performed after increasing the fuel injection amount by the fuel increase correction value as compared with the normal compression ignition combustion.
FIG. 7 shows the relationship between the input fuel and the in-cylinder pressure at which compression ignition is possible. By increasing the input fuel by increasing the fuel injection amount, the in-cylinder pressure at which compression ignition is possible decreases, and the engine compression It can be seen that compression ignition combustion is possible even under degradation of the system.

Ｓ１１での判定で火花点火燃焼領域の場合は、Ｓ１６へ進み、点火プラグを用いて、火花点火燃焼を行わせる。
本実施形態においては、図３のルーチンのＳ１２の部分が劣化判定手段に相当し、Ｓ１４、Ｓ１５の部分が着火性改善制御手段に相当する。
本実施形態によれば、エンジン圧縮系の劣化による圧縮圧力の低下は、低回転側ほど大きく、高回転側ほど小さく、エンジン回転数に対して感度を持つことから、低回転側での圧縮圧力と高回転側での圧縮圧力とに基づいて、エンジン圧縮系の劣化を判定することにより、的確に判定することができる。 If the spark ignition combustion region is determined in S11, the process proceeds to S16, and spark ignition combustion is performed using the spark plug.
In the present embodiment, the part of S12 in the routine of FIG. 3 corresponds to the deterioration determination means, and the parts of S14 and S15 correspond to the ignitability improvement control means.
According to the present embodiment, the compression pressure drop due to deterioration of the engine compression system is larger at the lower rotation side, smaller at the higher rotation side, and sensitive to the engine speed. It is possible to accurately determine the deterioration of the engine compression system on the basis of the compression pressure on the high rotation side.

また、本実施形態によれば、エンジン圧縮系の劣化による圧縮圧力の低下は、低回転側ほど大きく、高回転側ほど小さいことから、低回転側ほど圧縮圧力の低下により着火性が悪化するので、劣化と判定されたときに、エンジン回転数に応じて、エンジンの着火性を改善するように制御することにより、的確に対策できる。
また、本実施形態によれば、クランキング時に低回転側での圧縮圧力を検出し、減速燃料カット時に高回転側での圧縮圧力を検出することにより、エンジン圧縮系の劣化と関連する低回転側及び高回転側での圧縮圧力を的確に検出できる。 Further, according to the present embodiment, the decrease in the compression pressure due to the deterioration of the engine compression system is larger at the lower rotation side and smaller at the higher rotation side. When it is determined that the engine is deteriorated, an appropriate countermeasure can be taken by controlling so as to improve the ignitability of the engine according to the engine speed.
Further, according to the present embodiment, the low rotation speed associated with deterioration of the engine compression system is detected by detecting the compression pressure on the low rotation side during cranking and detecting the compression pressure on the high rotation side during deceleration fuel cut. It is possible to accurately detect the compression pressure on the side and the high rotation side.

また、本実施形態によれば、低回転側での圧縮圧力の初期値からの低下代Ｘと高回転側での圧縮圧力の初期値からの低下代Ｙとの差（Ｘ−Ｙ）又は比（Ｘ／Ｙ）が所定値以上の場合に、劣化と判定することにより、劣化を的確に判定できる。
また、本実施形態によれば、着火性の改善を燃料噴射量を増量補正することによって行い、エンジン回転数に応じて、燃料噴射量の増量補正値を可変制御することにより、エンジン圧縮系の劣化による着火性の悪化を確実に回避することができる。 Further, according to the present embodiment, the difference (X−Y) or ratio between the reduction margin X from the initial value of the compression pressure on the low rotation side and the reduction margin Y from the initial value of the compression pressure on the high rotation side. When (X / Y) is equal to or greater than a predetermined value, the deterioration can be accurately determined by determining the deterioration.
In addition, according to the present embodiment, the ignition performance is improved by increasing the fuel injection amount, and the fuel injection amount increase correction value is variably controlled in accordance with the engine speed, so that the engine compression system It is possible to reliably avoid deterioration of ignitability due to deterioration.

また、本実施形態によれば、エンジン回転数と劣化度合とに応じて、燃料噴射量の増量補正値を可変制御することにより、過不足のない補正が可能となる。
次に本発明の他の実施形態について説明する。本実施形態は、図３のフローに代えて、図８のフローを用いるものである。
図８は本実施形態でのエンジン圧縮系の劣化対応制御を含む燃焼制御のフローチャートであり、図３のフローと同一部分には同一符号を付して、異なる部分についてのみ説明する。 Further, according to the present embodiment, it is possible to perform correction without excess or deficiency by variably controlling the fuel injection amount increase correction value according to the engine speed and the degree of deterioration.
Next, another embodiment of the present invention will be described. In the present embodiment, the flow of FIG. 8 is used instead of the flow of FIG.
FIG. 8 is a flowchart of the combustion control including the engine compression system deterioration countermeasure control in this embodiment. The same parts as those in the flow of FIG. 3 are denoted by the same reference numerals, and only different parts will be described.

Ｓ１２での判定で、Ｘ−Ｙ≧所定値の場合には、エンジン圧縮系の劣化有りと判定して、Ｓ１７へ進む。
Ｓ１７では、図９のマップを参照し、エンジン回転数Ｎｅと、劣化度合に相当する低回転側で圧縮圧力の低下代Ｘとに応じて、マイナスオーバーラップ量（マイナスＯ／Ｌ量）を算出する。 If X−Y ≧ predetermined value is determined in S12, it is determined that the engine compression system has deteriorated, and the process proceeds to S17.
In S17, with reference to the map of FIG. 9, the minus overlap amount (minus O / L amount) is calculated according to the engine speed Ne and the compression pressure reduction allowance X on the low revolution side corresponding to the degree of deterioration. To do.

マイナスオーバーラップとは、排気行程と吸気行程との間で排気弁と吸気弁とが共に閉となる期間を持たせることであり、可変動弁装置により排気弁の閉時期を早め、及び／又は、吸気弁の開時期を遅らせることで、実現でき、マイナスオーバーラップを持たせることで、内部ＥＧＲ量（残ガス量）の増加により、筒内温度を上昇できる。
ここで、マイナスオーバーラップ量（期間の長さ）は、エンジン回転数Ｎｅが低いほど、劣化による圧縮圧力の低下が大となって着火性が悪化することから、着火性を改善するように、大きな値とし、また、劣化度合（低回転側での圧縮圧力の低下代Ｘ）が大きいほど、圧縮圧力の低下が大となって着火性が悪化することから、着火性を改善するように、大きな値とする。 The minus overlap is to give a period during which both the exhaust valve and the intake valve are closed between the exhaust stroke and the intake stroke, and advance the closing timing of the exhaust valve by a variable valve mechanism, and / or This can be realized by delaying the opening timing of the intake valve, and by providing a minus overlap, the in-cylinder temperature can be increased by increasing the internal EGR amount (residual gas amount).
Here, the amount of minus overlap (the length of the period) is such that the lower the engine speed Ne, the greater the decrease in compression pressure due to deterioration and the worse the ignitability. In order to improve the ignitability, the larger the deterioration degree (the lower the compression pressure decrease X on the low rotation side), the greater the deterioration of the compression pressure and the worse the ignitability. Use a large value.

そして、Ｓ１８へ進み、通常の圧縮着火燃焼に比べ、前記マイナスオーバーラップ量の分、マイナスオーバーラップ期間を持たせた上で、圧縮着火燃焼を行わせる。
図１０はマイナスオーバーラップ量と筒内温度との関係を示したもので、マイナスオーバーラップ期間を持たせて、これを大きくすることで、内部ＥＧＲの増加により、筒内温度が上昇し、エンジン圧縮系の劣化の下でも、圧縮着火燃焼が可能となることがわかる。 Then, the process proceeds to S18, and the compression ignition combustion is performed after a minus overlap period corresponding to the minus overlap amount as compared with the normal compression ignition combustion.
FIG. 10 shows the relationship between the minus overlap amount and the in-cylinder temperature. By giving a minus overlap period and enlarging it, the in-cylinder temperature rises due to an increase in internal EGR. It can be seen that compression ignition combustion is possible even under the deterioration of the compression system.

本実施形態においては、図８のルーチンのＳ１７、Ｓ１８の部分が着火性改善制御手段に相当する。
特に本実施形態によれば、着火性の改善をマイナスオーバーラップ期間を持たせることによって行い、エンジン回転数に応じて、マイナスオーバーラップ期間を可変制御することにより、エンジン圧縮系の劣化による着火性の悪化を低回転側ほど筒内温度を上昇させることによって確実に回避することができる。 In this embodiment, S17 and S18 in the routine of FIG. 8 correspond to the ignitability improvement control means.
In particular, according to the present embodiment, the ignitability is improved by providing a minus overlap period, and the minus overlap period is variably controlled according to the engine speed, so that the ignitability due to deterioration of the engine compression system is achieved. The deterioration can be reliably avoided by increasing the in-cylinder temperature at the lower rotation side.

また、特に本実施形態によれば、エンジン回転数と劣化度合とに応じて、マイナスオーバーラップ期間を可変制御することにより、過不足のない制御が可能となる。
次に本発明の更に他の実施形態について説明する。本実施形態は、図３のフローに代えて、図１１のフローを用いるものである。
図１１は本実施形態でのエンジン圧縮系の劣化対応制御を含む燃焼制御のフローチャートであり、図３のフローと同一部分には同一符号を付して、異なる部分についてのみ説明する。 In particular, according to the present embodiment, control without excess or deficiency is possible by variably controlling the minus overlap period in accordance with the engine speed and the degree of deterioration.
Next, still another embodiment of the present invention will be described. This embodiment uses the flow of FIG. 11 instead of the flow of FIG.
FIG. 11 is a flowchart of the combustion control including the engine compression system deterioration countermeasure control in this embodiment. The same parts as those in the flow of FIG. 3 are denoted by the same reference numerals, and only different parts will be described.

Ｘ−Ｙ≧所定値の場合には、エンジン圧縮系の劣化有りと判定して、Ｓ１９へ進む。
Ｓ１９では、図１２のテーブルを参照し、劣化度合に相当する低回転側で圧縮圧力の低下代Ｘに応じて、圧縮着火燃焼の最低回転数Ｎmin を算出する。
圧縮着火燃焼の最低回転数Ｎmin とは、図５の圧縮着火燃焼領域における低回転側の境界値（限界値）に相当するものであり、これ未満の回転数では、火花点火燃焼に切換えるられる。 When XY ≧ predetermined value, it is determined that the engine compression system has deteriorated, and the process proceeds to S19.
In S19, referring to the table of FIG. 12, the minimum rotation speed Nmin of compression ignition combustion is calculated according to the reduction pressure X of the compression pressure on the low rotation side corresponding to the degree of deterioration.
The minimum rotation speed Nmin of compression ignition combustion corresponds to the boundary value (limit value) on the low rotation side in the compression ignition combustion region of FIG. 5, and at a rotation speed less than this, switching to spark ignition combustion is performed.

ここで、圧縮着火燃焼の最低回転数Ｎmin は、劣化度合（低回転側での圧縮圧力の低下代Ｘ）が大きいほど、圧縮圧力の低下が大となって着火性が悪化することから、より広い範囲で、着火性を改善するように（着火性に優れる火花点火燃焼へ切換えるように）、高回転側の値とする。
そして、Ｓ２０へ進んで、現在のエンジン回転数Ｎｅを読込み、これを前記最低回転数Ｎmin と比較し、Ｎｅ＜Ｎmin か否かを判定する。 Here, since the minimum rotational speed Nmin of the compression ignition combustion is larger as the deterioration degree (the reduction pressure X of the compression pressure on the low rotation side) is larger, the lowering of the compression pressure becomes larger and the ignitability becomes worse. In order to improve the ignitability over a wide range (so as to switch to spark ignition combustion with excellent ignitability), the value is set on the high rotation side.
In S20, the current engine speed Ne is read and compared with the minimum engine speed Nmin to determine whether Ne <Nmin.

この判定の結果、ＮＯ、すなわち、Ｎｅ≧Ｎmin の場合は、圧縮着火燃焼が可能であると判定し、Ｓ１３へ進んで、圧縮着火燃焼を行わせる。
Ｓ２０での判定の結果、ＹＥＳ、すなわち、Ｎｅ＜Ｎmin の場合は、圧縮着火燃焼が困難であると判定し、Ｓ１６へ進んで、火花点火燃焼を行わせる。
本実施形態においては、図３のルーチンのＳ１９，Ｓ２０→Ｓ１６の部分が着火性改善制御手段に相当する。 If the result of this determination is NO, that is, if Ne ≧ Nmin, it is determined that compression ignition combustion is possible, and the routine proceeds to S13 where compression ignition combustion is performed.
If the result of determination in S20 is YES, that is, if Ne <Nmin, it is determined that compression ignition combustion is difficult, and the routine proceeds to S16 where spark ignition combustion is performed.
In this embodiment, the portions of S19, S20 → S16 in the routine of FIG. 3 correspond to the ignitability improvement control means.

特に本実施形態によれば、着火性の改善を、エンジン回転数が低回転側のときに、圧縮着火燃焼から火花点火燃焼に切換えることによって行うことにより、エンジン圧縮系の劣化による着火性の悪化を確実に回避することができる。
また、特に本実施形態によれば、着火性の改善に際し、圧縮着火燃焼を行わせる最低回転数Ｎmin を低回転側に変更することにより、前記最低回転数Ｎmin 未満で圧縮着火燃焼から火花点火燃焼に切換えることにより、簡単で的確な制御を実現できる。 In particular, according to the present embodiment, the improvement in ignitability is performed by switching from compression ignition combustion to spark ignition combustion when the engine speed is on the low speed side, thereby deteriorating ignitability due to deterioration of the engine compression system. Can be reliably avoided.
In particular, according to the present embodiment, when improving the ignitability, by changing the minimum rotational speed Nmin for performing the compression ignition combustion to the low rotational side, the compression ignition combustion is changed to the spark ignition combustion at less than the minimum rotational speed Nmin. By switching to, simple and accurate control can be realized.

また、特に本実施形態によれば、劣化度合に応じて、前記最低回転数Ｎmin を可変制御することにより、劣化度合を考慮した制御が可能となる。   Further, in particular, according to the present embodiment, it is possible to control in consideration of the degree of deterioration by variably controlling the minimum rotational speed Nmin according to the degree of deterioration.

本発明の一実施形態を示すエンジンのシステム図Engine system diagram showing an embodiment of the present invention 圧縮圧力の低下代Ｘ、Ｙの算出・記憶ルーチンのフローチャートFlow chart of calculation / storage routine for compression pressure reduction allowances X and Y 劣化対応制御を含む燃焼制御ルーチンのフローチャートFlow chart of combustion control routine including deterioration countermeasure control 圧縮着火燃焼／火花点火燃焼を行わせる運転領域マップの概略図Schematic diagram of operation region map for performing compression ignition combustion / spark ignition combustion 劣化によるエンジン回転数と圧縮圧力との関係の変化を示す図A diagram showing changes in the relationship between engine speed and compression pressure due to deterioration 燃料増量補正値のマップの概略図Schematic diagram of fuel increase correction value map 投入燃料と圧縮着火可能な筒内圧力との関係を示す図Diagram showing relationship between input fuel and in-cylinder pressure capable of compression ignition 本発明の他の実施形態（燃焼制御ルーチン）のフローチャートFlowchart of another embodiment (combustion control routine) of the present invention マイナスオーバーラップ量のマップの概略図Schematic diagram of minus overlap amount map マイナスオーバーラップ量と筒内温度との関係を示す図Diagram showing the relationship between the minus overlap amount and the in-cylinder temperature 本発明の更に他の実施形態（燃焼制御ルーチン）のフローチャートFlowchart of still another embodiment (combustion control routine) of the present invention 圧縮着火燃焼最低回転数のテーブルの概略図Schematic diagram of the table for compression ignition combustion minimum speed

符号の説明Explanation of symbols

４ 燃焼室
５ 吸気弁
７ 排気弁
９、１０ 可変動弁装置
１１ 燃料噴射弁
１２ 点火プラグ
１３ ＥＣＵ
１４ クランク角センサ
１５ 筒内圧センサ 4 Combustion chamber 5 Intake valve 7 Exhaust valve 9, 10 Variable valve device 11 Fuel injection valve 12 Spark plug 13 ECU
14 Crank angle sensor 15 In-cylinder pressure sensor

Claims (10)

少なくとも一部の運転領域で圧縮着火燃焼を行わせる内燃機関において、
低回転側での圧縮圧力と高回転側での圧縮圧力とをそれぞれ検出する圧縮圧力検出手段と、
低回転側での圧縮圧力と高回転側での圧縮圧力とに基づいて、機関の圧縮系の劣化を判定する劣化判定手段と、
劣化と判定されたときに、機関回転数に応じて、機関の着火性を改善するように制御する着火性改善制御手段と、
を備えることを特徴とする圧縮着火内燃機関の制御装置。 In an internal combustion engine that performs compression ignition combustion in at least a part of the operation region,
Compression pressure detecting means for detecting the compression pressure on the low rotation side and the compression pressure on the high rotation side,
A deterioration determining means for determining deterioration of the compression system of the engine based on the compression pressure on the low rotation side and the compression pressure on the high rotation side;
Ignitability improvement control means for controlling to improve the ignitability of the engine according to the engine speed when it is determined that the engine is deteriorated;
A control apparatus for a compression ignition internal combustion engine. 前記圧縮圧力検出手段は、クランキング時に低回転側での圧縮圧力を検出し、減速燃料カット時に高回転側での圧縮圧力を検出するものであることを特徴とする請求項１記載の圧縮着火内燃機関の制御装置。   2. The compression ignition according to claim 1, wherein the compression pressure detecting means detects a compression pressure on the low rotation side during cranking, and detects a compression pressure on the high rotation side during deceleration fuel cut. Control device for internal combustion engine. 前記劣化判定手段は、低回転側での圧縮圧力の初期値からの低下代と高回転側での圧縮圧力の初期値からの低下代との差又は比が所定値以上の場合に、劣化と判定することを特徴とする請求項１又は請求項２記載の圧縮着火内燃機関の制御装置。   The deterioration determining means determines that deterioration occurs when the difference or ratio between the reduction amount from the initial value of the compression pressure on the low rotation side and the reduction amount from the initial value of the compression pressure on the high rotation side is a predetermined value or more. The control apparatus for a compression ignition internal combustion engine according to claim 1 or 2, wherein the control is performed. 前記着火性改善制御手段は、燃料噴射量を増量補正するものであり、機関回転数に応じて、燃料噴射量の増量補正値を可変制御することを特徴とする請求項１〜請求項３のいずれか１つに記載の圧縮着火内燃機関の制御装置。   The ignitability improvement control means is for correcting an increase in the fuel injection amount, and variably controls the increase correction value for the fuel injection amount in accordance with the engine speed. The control apparatus of the compression ignition internal combustion engine as described in any one. 前記着火性改善制御手段は、機関回転数と劣化度合とに応じて、燃料噴射量の増量補正値を可変制御することを特徴とする請求項４記載の圧縮着火内燃機関の制御装置。   5. The control device for a compression ignition internal combustion engine according to claim 4, wherein the ignitability improvement control means variably controls the fuel injection amount increase correction value according to the engine speed and the degree of deterioration. 前記着火性改善制御手段は、排気行程と吸気行程との間で排気弁と吸気弁とが共に閉となるマイナスオーバーラップ期間を持たせるように制御するものであり、機関回転数に応じて、マイナスオーバーラップ期間を可変制御することを特徴とする請求項１〜請求項３のいずれか１つに記載の圧縮着火内燃機関の制御装置。   The ignitability improvement control means controls so as to have a minus overlap period in which the exhaust valve and the intake valve are both closed between the exhaust stroke and the intake stroke, and according to the engine speed, The control apparatus for a compression ignition internal combustion engine according to any one of claims 1 to 3, wherein the minus overlap period is variably controlled. 前記着火性改善制御手段は、機関回転数と劣化度合とに応じて、マイナスオーバーラップ期間を可変制御することを特徴とする請求項６記載の圧縮着火内燃機関の制御装置。   7. The control apparatus for a compression ignition internal combustion engine according to claim 6, wherein the ignitability improvement control means variably controls the minus overlap period according to the engine speed and the degree of deterioration. 前記着火性改善制御手段は、機関回転数が低回転側のときに、圧縮着火燃焼から火花点火燃焼に切換えるものであることを特徴とする請求項１〜請求項３のいずれか１つに記載の圧縮着火内燃機関の制御装置。   The ignition quality improvement control means switches from compression ignition combustion to spark ignition combustion when the engine speed is on the low rotation side. Control device for compression ignition internal combustion engine. 前記着火性改善制御手段は、圧縮着火燃焼を行わせる最低回転数を低回転側に変更することにより、前記最低回転数未満で圧縮着火燃焼から火花点火燃焼に切換えるものであることを特徴とする請求項８記載の圧縮着火内燃機関の制御装置。   The ignitability improvement control means switches the compression ignition combustion to the spark ignition combustion at less than the minimum rotation speed by changing the minimum rotation speed for performing the compression ignition combustion to the low rotation side. The control apparatus for a compression ignition internal combustion engine according to claim 8. 前記着火性改善制御手段は、劣化度合に応じて、低回転側に変更する前記最低回転数を可変制御することを特徴とする請求項９記載の圧縮着火内燃機関の制御装置。   10. The control apparatus for a compression ignition internal combustion engine according to claim 9, wherein the ignitability improvement control means variably controls the minimum rotational speed that is changed to a low rotational speed side according to the degree of deterioration.
JP2005226358A 2005-08-04 2005-08-04 Control device for compression ignition internal combustion engine Pending JP2007040218A (en)

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JP2010180771A (en) * 2009-02-05 2010-08-19 Denso Corp Fuel injection control device
DE102011121641A1 (en) 2011-01-05 2012-07-05 Mazda Motor Corp. Diesel engine for a vehicle and method of controlling the same

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JP2008267352A (en) * 2007-04-24 2008-11-06 Toyota Motor Corp Crank angle correction device and crank angle correction method
JP2010180771A (en) * 2009-02-05 2010-08-19 Denso Corp Fuel injection control device
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