JP4337831B2 - Fuel injection control device for internal combustion engine - Google Patents

Fuel injection control device for internal combustion engine Download PDF

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JP4337831B2
JP4337831B2 JP2006051681A JP2006051681A JP4337831B2 JP 4337831 B2 JP4337831 B2 JP 4337831B2 JP 2006051681 A JP2006051681 A JP 2006051681A JP 2006051681 A JP2006051681 A JP 2006051681A JP 4337831 B2 JP4337831 B2 JP 4337831B2
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fuel injection
fuel
ratio
injection valve
amount
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JP2007231754A (en
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宏之 北東
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Toyota Motor Corp
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Priority to EP07713064.9A priority patent/EP1989430B1/en
Priority to US12/085,833 priority patent/US7653475B2/en
Priority to PCT/IB2007/000449 priority patent/WO2007099425A1/en
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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
    • F02D41/3094—Controlling fuel injection the fuel injection being effected by at least two different injectors, e.g. one in the intake manifold and one in the cylinder
    • 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
    • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/2406—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
    • F02D41/2425—Particular ways of programming the data
    • F02D41/2429—Methods of calibrating or learning
    • F02D41/2451—Methods of calibrating or learning characterised by what is learned or calibrated
    • F02D41/2454—Learning of the air-fuel ratio control

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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)
  • Fuel-Injection Apparatus (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Description

本発明は、内燃機関の燃料噴射制御装置に関する。   The present invention relates to a fuel injection control device for an internal combustion engine.

気筒内へ直接的に燃料を噴射する第一燃料噴射弁と、吸気ポートへ燃料を噴射する第二燃料噴射弁とを具備し、これら二つの燃料噴射弁を使用して気筒内へ燃料を供給して均質燃焼を実施する内燃機関が公知である。このような内燃機関において、一般的に、燃焼空燃比は、低負荷側では理論空燃比よりリーンとされ、高負荷側では理論空燃比とされる。また、低負荷側では、均質混合気の均質性をより高めることを意図して、第二燃料噴射弁の燃料噴射割合を第一燃料噴射弁の燃料噴射割合より大きくし、高負荷側では、筒内温度を低下させて充填効率をより高めることを意図して、第一燃料噴射弁の燃料噴射割合を第二燃料噴射弁の燃料噴射割合より大きくしている。   It has a first fuel injection valve that injects fuel directly into the cylinder and a second fuel injection valve that injects fuel into the intake port, and supplies fuel into the cylinder using these two fuel injection valves An internal combustion engine that performs homogeneous combustion is known. In such an internal combustion engine, generally, the combustion air-fuel ratio is leaner than the stoichiometric air-fuel ratio on the low load side, and is the stoichiometric air-fuel ratio on the high load side. Also, on the low load side, the fuel injection ratio of the second fuel injection valve is made larger than the fuel injection ratio of the first fuel injection valve with the intention of increasing the homogeneity of the homogeneous mixture, and on the high load side, The fuel injection ratio of the first fuel injection valve is made larger than the fuel injection ratio of the second fuel injection valve in an attempt to further increase the charging efficiency by lowering the in-cylinder temperature.

ところで、気筒内へ供給される燃料量を正確に制御するためには、各燃料噴射弁からの燃料噴射量を補正することが必要である。前述の内燃機関の場合には、常に二つの燃料噴射弁から燃料が噴射されるために、燃料噴射弁毎に異なる燃料噴射補正係数を設定することは困難であり、空燃比センサにより検出される排気ガスの空燃比から実際に気筒内へ供給された燃料量を算出し、必要供給燃料量に対する過不足に基づき、二つの燃料噴射弁に対する同一の燃料噴射補正係数を学習することとなる。   Incidentally, in order to accurately control the amount of fuel supplied into the cylinder, it is necessary to correct the fuel injection amount from each fuel injection valve. In the case of the above-described internal combustion engine, fuel is always injected from the two fuel injection valves. Therefore, it is difficult to set a different fuel injection correction coefficient for each fuel injection valve, which is detected by an air-fuel ratio sensor. The amount of fuel actually supplied into the cylinder is calculated from the air-fuel ratio of the exhaust gas, and the same fuel injection correction coefficient for the two fuel injection valves is learned based on the excess and deficiency with respect to the required amount of fuel supplied.

このように学習された燃料噴射補正係数は、学習時の第一燃料噴射弁及び第二燃料噴射弁の燃料噴射割合と、厳密には、学習時の必要供給燃料量とに対してだけ有効である。それにより、燃料噴射割合が異なる運転領域毎に補正係数を学習することが提案されている（例えば、特許文献１参照）。   The fuel injection correction coefficient learned in this way is effective only for the fuel injection ratios of the first fuel injection valve and the second fuel injection valve at the time of learning and, strictly speaking, the required fuel supply amount at the time of learning. is there. Thus, it has been proposed to learn a correction coefficient for each operation region having a different fuel injection ratio (see, for example, Patent Document 1).

特開平３−１８５２４２JP 3-185242 特開２００５−３１５１２４JP-A-2005-315124

一般的に、空燃比センサは、理論空燃比近傍では正確な空燃比を検出可能であり、理論空燃比の均質燃焼時において、この時の燃料噴射割合に対する燃料噴射補正係数を学習することはできる。しかしながら、空燃比センサは、ＮＯX生成量を抑制したリーン空燃比の均質燃焼時のような約１８よりリーンな空燃比を正確に検出することができず、リーン空燃比の均質燃焼時には、この時の燃料噴射割合に対して正確な燃料噴射補正係数を学習することはできない。また、空燃比センサは、機関排気系に配置されたＮＯX吸蔵還元触媒から吸蔵ＮＯXを放出して還元浄化する再生処理のために燃焼空燃比をリッチにする時（以下、リッチスパイク）のようなリッチ空燃比も正確に検出することができず、この時の燃料噴射割合に対して正確な燃料噴射補正係数を学習することはできない。 In general, an air-fuel ratio sensor can detect an accurate air-fuel ratio in the vicinity of the theoretical air-fuel ratio, and can learn a fuel injection correction coefficient for the fuel injection ratio at this time when the stoichiometric air-fuel ratio is homogeneously combusted. . However, the air-fuel ratio sensor cannot accurately detect an air-fuel ratio leaner than about 18 as in the homogeneous combustion of the lean air-fuel ratio in which the amount of NO x produced is suppressed. It is not possible to learn an accurate fuel injection correction coefficient for the current fuel injection ratio. Further, the air-fuel ratio sensor is used when the combustion air-fuel ratio is made rich (hereinafter referred to as a rich spike) for the regeneration process in which the stored NO X is released from the NO X storage reduction catalyst disposed in the engine exhaust system for reduction purification. Such a rich air-fuel ratio cannot be accurately detected, and an accurate fuel injection correction coefficient cannot be learned for the fuel injection ratio at this time.

それにより、リーン空燃比の均質燃焼時には、燃料噴射量を正確に補正することができず、必要量より多い燃料が気筒内へ供給されてＮＯX生成量が増大したり、又は、必要量より少ない燃料しか気筒内へ供給されずに、必要トルクを発生させることができなかったりすることがある。また、リッチスパイク時にも燃料噴射量を正確に補正することができず、ＮＯX吸蔵還元触媒装置の再生処理が不十分となったり、再生処理のために必要以上の燃料が供給されて燃料消費を悪化させたりする。 As a result, during homogeneous combustion with a lean air-fuel ratio, the fuel injection amount cannot be accurately corrected, and more fuel than necessary is supplied into the cylinder, resulting in an increase in the amount of NO x generated, or more than necessary. There may be a case where only a small amount of fuel is supplied into the cylinder and the required torque cannot be generated. In addition, the fuel injection amount cannot be accurately corrected even during a rich spike, and the regeneration process of the NO x storage reduction catalyst device becomes insufficient, or more fuel is supplied than necessary for the regeneration process. Worsen.

従って、本発明の目的は、気筒内へ燃料を噴射する第一燃料噴射弁と吸気ポートへ燃料を噴射する第二燃料噴射弁とを具備し、第一燃料噴射弁と第二燃料噴射弁との両方を使用して気筒内へ燃料を供給し、燃焼空燃比を理論空燃比近傍とし、第一燃料噴射弁及び第二燃料噴射弁の燃料噴射割合を第一燃料噴射割合とする第一燃焼と、燃焼空燃比を第一燃焼とは異なる空燃比とし、第一燃料噴射弁及び第二燃料噴射弁の燃料噴射割合を第二燃料噴射割合とする第二燃焼とを切り換えて実施する内燃機関の燃料噴射制御装置において、第二燃焼時の燃料噴射補正係数を学習可能とすることである。   Accordingly, an object of the present invention includes a first fuel injection valve that injects fuel into a cylinder and a second fuel injection valve that injects fuel into an intake port, and the first fuel injection valve, the second fuel injection valve, Both are used to supply fuel into the cylinder, the combustion air-fuel ratio is close to the stoichiometric air-fuel ratio, and the first fuel injection ratio of the first fuel injection valve and the second fuel injection valve is the first fuel injection ratio. An internal combustion engine in which the combustion air-fuel ratio is different from that of the first combustion and the second combustion is switched between the first fuel injection valve and the second fuel injection ratio. In the fuel injection control apparatus, the fuel injection correction coefficient at the time of the second combustion can be learned.

本発明による請求項１に記載の内燃機関の燃料噴射制御装置は、気筒内へ燃料を噴射する第一燃料噴射弁と吸気ポートへ燃料を噴射する第二燃料噴射弁とを具備し、前記第一燃料噴射弁と前記第二燃料噴射弁との両方を使用して気筒内へ燃料を供給し、燃焼空燃比を理論空燃比近傍とし、前記第一燃料噴射弁及び前記第二燃料噴射弁の燃料噴射割合を第一燃料噴射割合とする第一燃焼と、燃焼空燃比をリーン空燃比又はリッチ空燃比とするために、理論空燃比を実現する基本燃料供給量を減量補正又は増量補正し、前記第一燃料噴射弁及び前記第二燃料噴射弁の燃料噴射割合を第二燃料噴射割合とする第二燃焼とを切り換えて実施する内燃機関の燃料噴射制御装置において、前記第二燃焼時には、前記第一燃料噴射弁から噴射される燃料噴射量及び前記第二燃料噴射弁から噴射される燃料噴射量が、現在の前記基本燃料供給量の領域における同一の燃料噴射補正係数により補正され、前記燃料噴射補正係数は、前記第二燃焼が実施されるときに、前記基本燃料供給量が気筒内へ供給されるように燃料噴射割合を前記第二燃料噴射割合として前記第一燃料噴射弁の燃料噴射量及び前記第二燃料噴射弁の燃料噴射量を設定して燃料噴射を実施した場合の前記基本燃料供給量と実際に気筒内へ供給された供給燃料量との比として、前記基本燃料供給量に基づき分割された前記領域毎に学習されることを特徴とする。 According to a first aspect of the present invention, there is provided a fuel injection control device for an internal combustion engine comprising a first fuel injection valve for injecting fuel into a cylinder and a second fuel injection valve for injecting fuel into an intake port. The fuel is supplied into the cylinder using both the one fuel injection valve and the second fuel injection valve, the combustion air-fuel ratio is made close to the theoretical air-fuel ratio, and the first fuel injection valve and the second fuel injection valve In order to set the fuel injection ratio to the first fuel injection ratio and the combustion air-fuel ratio to the lean air-fuel ratio or the rich air-fuel ratio, the basic fuel supply amount for realizing the stoichiometric air-fuel ratio is corrected to decrease or increase, In a fuel injection control device for an internal combustion engine that performs switching between second combustion with a fuel injection ratio of the first fuel injection valve and the second fuel injection valve as a second fuel injection ratio, during the second combustion, Fuel injection injected from the first fuel injection valve And the fuel injection amount injected from the second fuel injection valve is corrected by the same fuel injection correction coefficient in the current basic fuel supply region, and the second combustion is performed as the fuel injection correction coefficient. The fuel injection rate of the first fuel injection valve and the fuel injection amount of the second fuel injection valve are set so that the fuel injection rate is the second fuel injection rate so that the basic fuel supply amount is supplied into the cylinder. Is calculated for each of the regions divided based on the basic fuel supply amount as a ratio of the basic fuel supply amount and the actual fuel supply amount supplied into the cylinder. It is characterized by that.

また、本発明による請求項２に記載の内燃機関の燃料噴射制御装置は、請求項１に記載の内燃機関の燃料噴射制御装置において、前記第二燃焼時の前記第一燃料噴射弁及び前記第二燃料噴射弁の燃料噴射量は、空燃比センサの出力に基づくフィードバック補正が実施されることなく、学習された前記燃料噴射補正係数により補正されることを特徴とする。   According to a second aspect of the present invention, there is provided the internal combustion engine fuel injection control apparatus according to the first aspect, wherein the first fuel injection valve and the first fuel injection valve during the second combustion are used. The fuel injection amount of the two fuel injection valves is corrected by the learned fuel injection correction coefficient without performing feedback correction based on the output of the air-fuel ratio sensor.

本発明による請求項１に記載の内燃機関の燃料噴射制御装置によれば、空燃比センサにより正確に空燃比を検出することができない第二燃焼時においては、第二燃焼における第二燃料噴射割合に対する第一燃料噴射弁及び第二燃料噴射弁の燃料噴射補正係数を学習することができないために、第二燃焼が実施されるときに、燃料噴射割合を第二燃焼時の第二燃料噴射割合として、空燃比センサにより正確に空燃比を検出することができるようにするために、基本燃料供給量が気筒内へ供給されるように燃料噴射割合を第二燃料噴射割合として第一燃料噴射弁の燃料噴射量及び第二燃料噴射弁の燃料噴射量を設定して燃料噴射を実施した場合の基本燃料供給量と実際に気筒内へ供給された供給燃料量との比として、基本燃料供給量に基づき分割された領域毎に学習するようになっている。 According to the fuel injection control device for an internal combustion engine according to claim 1 of the present invention, at the time of the second combustion in which the air-fuel ratio cannot be accurately detected by the air-fuel ratio sensor, the second fuel injection ratio in the second combustion. When the second combustion is performed because the fuel injection correction coefficients of the first fuel injection valve and the second fuel injection valve cannot be learned, the fuel injection ratio is set to the second fuel injection ratio during the second combustion. In order to enable the air-fuel ratio sensor to accurately detect the air-fuel ratio, the first fuel injection valve is set with the fuel injection ratio as the second fuel injection ratio so that the basic fuel supply amount is supplied into the cylinder. The basic fuel supply amount as a ratio of the basic fuel supply amount when the fuel injection is performed with the fuel injection amount of the second fuel injection valve set and the fuel injection amount of the second fuel injection valve and the actual fuel supply amount supplied into the cylinder Split based on It is adapted to learning in the each region.

また、本発明による請求項２に記載の内燃機関の燃料噴射制御装置によれば、請求項１に記載の内燃機関の燃料噴射制御装置において、基本燃料供給量に基づき分割された領域毎に学習された第二燃焼における燃料噴射補正係数は正確なものであり、第二燃焼時において、第一燃料噴射弁及び第二燃料噴射弁のそれぞれの燃料噴射量を、空燃比センサの出力に基づくフィードバック補正を実施することなく、このように学習された燃料噴射補正係数により補正することより、第二燃焼時において、必要量の燃料を確実に気筒内へ供給することが可能となる。 According to the fuel injection control device for an internal combustion engine according to claim 2 of the present invention, in the fuel injection control device for the internal combustion engine according to claim 1, learning is performed for each region divided based on the basic fuel supply amount. The corrected fuel injection correction coefficient in the second combustion is accurate, and during the second combustion, the respective fuel injection amounts of the first fuel injection valve and the second fuel injection valve are fed back based on the output of the air-fuel ratio sensor. By correcting with the fuel injection correction coefficient learned in this way without performing correction, it is possible to reliably supply the required amount of fuel into the cylinder during the second combustion.

図１は本発明による燃料噴射制御装置が取り付けられる内燃機関を示す概略図である。同図において、１は機関本体であり、２は各気筒共通のサージタンクである。３はサージタンク２と各気筒とを連通する吸気マニホルドであり、４はサージタンク２の上流側の吸気通路である。吸気通路４におけるサージタンク２の直上流側にはスロットル弁５が配置されている。吸気通路４のスロットル弁５より上流側には、吸気量を測定するためのエアフローメータ６が配置され、最上流部にはエアクリーナ７が配置される。   FIG. 1 is a schematic view showing an internal combustion engine to which a fuel injection control device according to the present invention is attached. In the figure, 1 is an engine body, and 2 is a surge tank common to each cylinder. An intake manifold 3 communicates the surge tank 2 and each cylinder, and 4 is an intake passage on the upstream side of the surge tank 2. A throttle valve 5 is disposed in the intake passage 4 immediately upstream of the surge tank 2. An air flow meter 6 for measuring the intake air amount is disposed upstream of the throttle valve 5 in the intake passage 4, and an air cleaner 7 is disposed in the most upstream part.

８は各気筒に連通する排気マニホルドであり、排気マニホルド８の下流側の排気通路９には、上流側のＮＯX吸蔵還元触媒装置１０と、下流側の三元触媒装置１１とが直列に配置され、ＮＯX吸蔵還元触媒装置１０の上流側には、排気ガスの空燃比を検出可能な空燃比センサ１２が配置され、三元触媒装置１１の下流側には、排気ガスの空燃比がリッチであるかリーンであるかを検出可能な酸素センサ１３が配置されている。酸素センサ１３の出力に基づき、空燃比センサ１２の出力のリッチ側又はリーン側へのずれを補正するようになっている。１４は各気筒内へ直接的に燃料を噴射するための第一燃料噴射弁であり、１５は各気筒の吸気ポートへ燃料を噴射するための第二燃料噴射弁である。 An exhaust manifold 8 communicates with each cylinder. An upstream NO x storage reduction catalyst device 10 and a downstream three-way catalyst device 11 are arranged in series in an exhaust passage 9 downstream of the exhaust manifold 8. An air-fuel ratio sensor 12 capable of detecting the air-fuel ratio of the exhaust gas is disposed upstream of the NO x storage reduction catalyst device 10, and the air-fuel ratio of the exhaust gas is rich on the downstream side of the three-way catalyst device 11. An oxygen sensor 13 that can detect whether the sensor is lean or lean is disposed. Based on the output of the oxygen sensor 13, the deviation of the output of the air-fuel ratio sensor 12 to the rich side or the lean side is corrected. 14 is a first fuel injection valve for directly injecting fuel into each cylinder, and 15 is a second fuel injection valve for injecting fuel into the intake port of each cylinder.

本内燃機関は、第一燃料噴射弁１４により吸気行程中に燃料を噴射すると共に、第二燃料噴射弁１５により吸気行程中（吸気同期）に又は吸気行程以前の排気行程中等（吸気非同期）に燃料を噴射し、これら二つの燃料噴射弁１４及び１５から噴射された燃料によって気筒内に均質混合気を形成して均質燃焼を実施する。但し、機関負荷が設定負荷以上の高負荷側領域では、均質混合気の空燃比は理論空燃比（又は理論空燃比より僅かにリッチなリッチ空燃比）とし、機関負荷が設定負荷未満の低負荷側領域では、均質混合気の空燃比は理論空燃比よりリーンなリーン空燃比として燃料消費を抑制するようになっている。このリーン空燃比は、ＮＯX生成量が抑制されるように１８以上が選択される。以下、理論空燃比での燃焼を第一燃焼とし、リーン空燃比での燃焼を第二燃焼として説明する。 The internal combustion engine injects fuel during the intake stroke by the first fuel injection valve 14 and during the intake stroke (intake synchronization) by the second fuel injection valve 15 or during the exhaust stroke before the intake stroke (intake asynchronous). The fuel is injected, and a homogeneous mixture is formed in the cylinder by the fuel injected from these two fuel injection valves 14 and 15 to perform homogeneous combustion. However, in the high load region where the engine load is equal to or higher than the set load, the air-fuel ratio of the homogeneous mixture is the stoichiometric air-fuel ratio (or a rich air-fuel ratio slightly richer than the stoichiometric air-fuel ratio) and the engine load is less than the set load. In the side region, the air-fuel ratio of the homogeneous mixture is leaner than the stoichiometric air-fuel ratio, so that fuel consumption is suppressed. The lean air-fuel ratio is selected to be 18 or more so that the NO x generation amount is suppressed. Hereinafter, the combustion at the stoichiometric air-fuel ratio will be described as the first combustion, and the combustion at the lean air-fuel ratio will be described as the second combustion.

第一燃料噴射弁１４から気筒内へ直接的に噴射された燃料は、気筒内で気化する際に気筒内の温度を十分に低下させるために、吸気充填効率を高めるのに有利である。一方、第二燃料噴射弁１５から噴射された燃料は、吸気と共に気筒内へ供給されるために、気筒内での燃料の均質化に有利である。それにより、高い機関出力が必要な第一燃焼においては、必要な各供給燃料量に対して、第二燃料噴射弁１５から噴射される燃料量を少なくして、その分、第一燃料噴射弁１４から噴射される燃料量を多くすることが好ましく、第一燃料噴射弁１４及び第二燃料噴射弁１５の燃料噴射割合は、例えば、７：３のように設定される。また、それほど高い機関出力は必要とせずに、均質混合気の均質性を高めて燃焼を安定化させることが必要な第二燃焼においては、必要な各供給燃料量に対して、第一燃料噴射弁１４から噴射される燃料量を少なくして、その分、第二燃料噴射弁１５から噴射される燃料量を多くすることが好ましく、第一燃料噴射弁１４及び第二燃料噴射弁１５の燃料噴射割合は、例えば、３：７のように設定される。   The fuel directly injected into the cylinder from the first fuel injection valve 14 is advantageous in increasing the intake charging efficiency in order to sufficiently reduce the temperature in the cylinder when vaporizing in the cylinder. On the other hand, since the fuel injected from the second fuel injection valve 15 is supplied into the cylinder together with the intake air, it is advantageous for homogenizing the fuel in the cylinder. Accordingly, in the first combustion that requires high engine output, the amount of fuel injected from the second fuel injection valve 15 is reduced with respect to each required amount of supplied fuel, and the first fuel injection valve correspondingly. It is preferable to increase the amount of fuel injected from 14, and the fuel injection ratio of the first fuel injection valve 14 and the second fuel injection valve 15 is set to 7: 3, for example. In the second combustion, which does not require a very high engine output and it is necessary to stabilize the combustion by increasing the homogeneity of the homogeneous mixture, the first fuel injection is performed for each required amount of supplied fuel. It is preferable to reduce the amount of fuel injected from the valve 14 and increase the amount of fuel injected from the second fuel injection valve 15 correspondingly, and the fuel of the first fuel injection valve 14 and the second fuel injection valve 15 The injection ratio is set as 3: 7, for example.

第一燃焼においても均質性は必要であり、供給燃料量の３０％は第二燃料噴射弁１５によって噴射するようになっている。一方、第二燃焼においては、全ての供給燃料量を第二燃料噴射弁１５により噴射することが考えられるが、第一燃料噴射弁１４の燃料噴射が停止されると、気筒内に開口する第一燃料噴射弁１４の噴孔にデポジットが堆積して噴孔が詰まることがある。それにより、第二燃焼において、供給燃料量の３０％は第一燃料噴射弁１４により噴射するようになっている。   Even in the first combustion, homogeneity is necessary, and 30% of the supplied fuel amount is injected by the second fuel injection valve 15. On the other hand, in the second combustion, it is conceivable that all the supplied fuel amount is injected by the second fuel injection valve 15, but when the fuel injection of the first fuel injection valve 14 is stopped, the second fuel injection valve 14 opens into the cylinder. Deposits may accumulate in the nozzle hole of one fuel injection valve 14 and the nozzle hole may be clogged. Thereby, in the second combustion, 30% of the supplied fuel amount is injected by the first fuel injection valve 14.

ところで、気筒内への供給燃料量を正確に制御するためには、第一燃料噴射弁１４及び第二燃料噴射弁１５からの燃料噴射量を補正することが必要である。本内燃機関のように、常に二つの燃料噴射弁から燃料が噴射される場合には、第一燃料噴射弁１４及び第二燃料噴射弁から実際に噴射されたそれぞれの燃料噴射量を把握することは困難である。それにより、燃料噴射弁毎に異なる燃料噴射補正係数を設定することは難しく、空燃比センサ１２により検出される排気ガスの空燃比から実際の気筒内への供給燃料量（第一燃料噴射弁１４及び第二燃料噴射弁１５から噴射された燃料噴射量の合計）を算出し、この供給燃料量の必要供給燃料量に対する過不足に基づき、第一燃料噴射弁１４及び第二燃料噴射弁１５に対する同一の燃料噴射補正係数を学習することとなる。   Incidentally, in order to accurately control the amount of fuel supplied into the cylinder, it is necessary to correct the fuel injection amounts from the first fuel injection valve 14 and the second fuel injection valve 15. When fuel is always injected from two fuel injection valves as in this internal combustion engine, the respective fuel injection amounts actually injected from the first fuel injection valve 14 and the second fuel injection valve must be grasped. It is difficult. Accordingly, it is difficult to set a different fuel injection correction coefficient for each fuel injection valve, and the amount of fuel supplied from the air-fuel ratio of the exhaust gas detected by the air-fuel ratio sensor 12 to the actual cylinder (the first fuel injection valve 14). And the total fuel injection amount injected from the second fuel injection valve 15), and based on the excess or deficiency of the supplied fuel amount with respect to the required supply fuel amount, the first fuel injection valve 14 and the second fuel injection valve 15 are calculated. The same fuel injection correction coefficient is learned.

このように学習された燃料噴射補正係数は、学習時の第一燃料噴射弁１４及び第二燃料噴射弁１５の燃料噴射割合と、厳密には、学習時の必要供給燃料量とに対してだけ有効である。例えば、必要供給燃料量が２０ｍｍ3である時に、第一燃料噴射弁１４及び第二燃料噴射弁１５の燃料噴射割合が７：３であれば、第一燃料噴射弁１４は１４ｍｍ3の燃料を噴射することが要求され、第二燃料噴射弁１５は６ｍｍ3の燃料を噴射することが要求される。また、第一燃料噴射弁１４及び第二燃料噴射弁１５の燃料噴射割合が３：７であれば、第一燃料噴射弁１４は６ｍｍ3の燃料を噴射することが要求され、第二燃料噴射弁１５は１４ｍｍ3の燃料を噴射することが要求される。 The fuel injection correction coefficient learned in this way is only for the fuel injection ratios of the first fuel injection valve 14 and the second fuel injection valve 15 at the time of learning and, strictly speaking, the necessary fuel supply amount at the time of learning. It is valid. For example, when the required fuel supply amount is 20 mm 3 and the fuel injection ratio of the first fuel injection valve 14 and the second fuel injection valve 15 is 7: 3, the first fuel injection valve 14 supplies 14 mm 3 of fuel. The second fuel injection valve 15 is required to inject 6 mm 3 of fuel. Further, if the fuel injection ratio of the first fuel injection valve 14 and the second fuel injection valve 15 is 3: 7, the first fuel injection valve 14 is required to inject 6 mm 3 of fuel, and the second fuel injection The valve 15 is required to inject 14 mm 3 of fuel.

このような場合において、もし、第一燃料噴射弁１４は要求に対して８０％の燃料を噴射することしかできず、また、第二燃料噴射弁１５は要求に対して９０％の燃料を噴射することしかできないとすれば、燃料噴射割合が７：３の時に算出される燃料噴射補正係数は、２０／（１４＊０．８＋６＊０．９）＝１．２０となり、また、燃料噴射割合が３：７の時に算出される燃料噴射補正係数は、２０／（６＊０．８＋１４＊０．９）＝１．１５となる。もちろん、これらの燃料噴射補正係数の算出に際して、（ ）内の値は、空燃比センサ１２により検出される排気ガスの実際の空燃比に基づく実際の供給燃料量である。このように、燃料噴射割合が異なれば、第一燃料噴射弁１４及び第二燃料噴射弁１５の共通の燃料噴射補正係数は明らかに異なる値となり、また、必要供給燃料量が変化しても燃料噴射補正係数は異なる値となる。   In such a case, the first fuel injection valve 14 can only inject 80% of the fuel to the demand, and the second fuel injection valve 15 injects 90% of the fuel to the demand. If it can only be done, the fuel injection correction coefficient calculated when the fuel injection ratio is 7: 3 is 20 / (14 * 0.8 + 6 * 0.9) = 1.20, and the fuel injection ratio The fuel injection correction coefficient calculated when is 3: 7 is 20 / (6 * 0.8 + 14 * 0.9) = 1.15. Of course, when calculating these fuel injection correction coefficients, the value in () is the actual amount of fuel supplied based on the actual air-fuel ratio of the exhaust gas detected by the air-fuel ratio sensor 12. As described above, when the fuel injection ratios are different, the common fuel injection correction coefficient of the first fuel injection valve 14 and the second fuel injection valve 15 is obviously different, and even if the required supply fuel amount changes, the fuel The injection correction coefficient has different values.

それにより、燃料噴射割合が異なる第一燃焼及び第二燃焼とで、それぞれに必要供給燃料量毎の燃料噴射補正係数を学習することが考えられるが、空燃比センサ１２は、第二燃焼のようなリーン空燃比を正確に検出することができず、すなわち、この時の実際の供給燃料量を把握することができず、そのままでは、第二燃焼時において、燃料噴射補正係数を学習することはできない。   Thereby, it is conceivable to learn the fuel injection correction coefficient for each required supply fuel amount in the first combustion and the second combustion with different fuel injection ratios. It is not possible to accurately detect the lean air-fuel ratio, that is, it is impossible to grasp the actual amount of fuel supplied at this time, and as it is, it is not possible to learn the fuel injection correction coefficient during the second combustion. Can not.

本燃料噴射制御装置は、図２に示すフローチャートにより、第二燃焼時の燃料噴射補正係数ｋ２ｎの学習を可能としている。先ず、ステップ１０１において、要求機関負荷Ｌが設定負荷Ｌ’以上であるか否かが判断される。この判断が肯定される時には、理論空燃比の第一燃焼の運転領域であり、ステップ１１０において、機関負荷と機関回転数等とに基づく理論空燃比運転に必要な基本供給燃料量Ｑｂに空燃比センサ１２のフィードバック補正係数ｆと第一燃料噴射補正係数ｋ１ｎとが乗算されて供給燃料量Ｑが算出される。次いで、ステップ１１１において、第一燃焼の第一燃料噴射割合（例えば、７：３）に基づき供給燃料量Ｑを気筒内へ供給するために、第一燃料噴射弁１４及び第二燃料噴射弁１５のそれぞれの燃料噴射量が設定され、第一燃焼が実施される。すなわち、基本供給燃料量Ｑｂを第一燃料噴射割合で噴射するための第一燃料噴射弁１４及び第二燃料噴射弁１５のそれぞれの燃料噴射量が、同一の第一燃料噴射補正係数ｋ１ｎによって補正されることとなる。ここで、気筒内へ供給されるべき必要供給燃料量は、基本供給燃料量Ｑｂである。   The fuel injection control device can learn the fuel injection correction coefficient k2n at the time of the second combustion according to the flowchart shown in FIG. First, in step 101, it is determined whether or not the requested engine load L is equal to or greater than a set load L '. When this determination is affirmative, it is the first combustion operation region of the stoichiometric air-fuel ratio. The supplied fuel amount Q is calculated by multiplying the feedback correction coefficient f of the sensor 12 and the first fuel injection correction coefficient k1n. Next, in step 111, the first fuel injection valve 14 and the second fuel injection valve 15 are supplied in order to supply the supplied fuel amount Q into the cylinder based on the first fuel injection ratio (for example, 7: 3) of the first combustion. Each fuel injection amount is set, and the first combustion is performed. That is, the fuel injection amounts of the first fuel injection valve 14 and the second fuel injection valve 15 for injecting the basic supply fuel amount Qb at the first fuel injection ratio are corrected by the same first fuel injection correction coefficient k1n. Will be. Here, the required supply fuel amount to be supplied into the cylinder is the basic supply fuel amount Qb.

第一燃料噴射補正係数ｋ１ｎは、図３に示すように、第一燃焼の基本供給燃料量Ｑｂの範囲において、例えば、三つに分割された領域毎に設定される。第一燃焼において、空燃比センサ１２により検出された排気ガスの空燃比が理論空燃比となるように、第一燃料噴射補正係数ｋ１ｎにより補正された基本供給燃料量Ｑｂをさらに補正するためのフィードバック補正係数ｆが算出される。第一燃料噴射補正係数ｋ１ｎは、各領域の運転時において、算出されたフィードバック補正係数ｆを１にするように更新される。   As shown in FIG. 3, the first fuel injection correction coefficient k1n is set, for example, for each of the three divided areas in the range of the basic supply fuel amount Qb for the first combustion. In the first combustion, feedback for further correcting the basic supply fuel amount Qb corrected by the first fuel injection correction coefficient k1n so that the air-fuel ratio of the exhaust gas detected by the air-fuel ratio sensor 12 becomes the stoichiometric air-fuel ratio. A correction coefficient f is calculated. The first fuel injection correction coefficient k1n is updated so that the calculated feedback correction coefficient f is set to 1 during operation in each region.

一方、要求機関負荷Ｌが設定負荷Ｌ’未満であれば、リーン空燃比の第二燃焼での運転領域であり、ステップ１０１の判断が否定されてステップ１０２へ進む。ステップ１０２では、機関停止時に０にリセットされるフラグＦが１であるか否かが判断される。当初は、フラグＦは０であり、ステップ１０２の判断は否定されてステップ１０５へ進む。ステップ１０５において、機関負荷と機関回転数等とに基づく理論空燃比運転に必要な基本供給燃料量Ｑｂはそのまま供給燃料量Ｑとされる。   On the other hand, if the requested engine load L is less than the set load L ′, it is an operating region in the second combustion with a lean air-fuel ratio, the determination in step 101 is negative, and the routine proceeds to step 102. In step 102, it is determined whether or not a flag F that is reset to 0 when the engine is stopped is 1. Initially, the flag F is 0, the determination in step 102 is denied, and the process proceeds to step 105. In step 105, the basic supply fuel amount Qb necessary for the theoretical air-fuel ratio operation based on the engine load, the engine speed, etc. is set as the supply fuel amount Q as it is.

現在は、要求機関負荷Ｌが設定負荷Ｌ’未満である第二燃焼での運転領域であるが、フラグＦが０の時、すなわち、機関始動当初は、燃焼空燃比をリーン空燃比とするための基本供給燃料量Ｑｂの減量補正は実施しない。次いで、ステップ１０６において、第二燃焼の第二燃料噴射割合（例えば、３：７）に基づき供給燃料量Ｑを気筒内へ供給するために、第一燃料噴射弁１４及び第二燃料噴射弁１５のそれぞれの燃料噴射量が設定され、理論空燃比の第一燃焼が実施される。   Currently, it is an operation region in the second combustion in which the required engine load L is less than the set load L ′, but when the flag F is 0, that is, when the engine is started, the combustion air-fuel ratio is made the lean air-fuel ratio. No reduction correction of the basic supply fuel amount Qb is performed. Next, in step 106, the first fuel injection valve 14 and the second fuel injection valve 15 are supplied in order to supply the supplied fuel amount Q into the cylinder based on the second fuel injection ratio (for example, 3: 7) of the second combustion. Are set, and the first combustion at the stoichiometric air-fuel ratio is performed.

次いで、ステップ１０７に進み、この時の第一燃焼において、空燃比センサ１２により検出される理論空燃比近傍の排気ガスの空燃比に基づき、実際の供給燃料量Ｑ’を算出し、基本供給燃料量と実際の供給燃料量Ｑ’との比Ｑ／Ｑ’を第二燃料噴射補正係数ｋ２ｎとして学習する。第二燃料噴射補正係数ｋ２ｎは、図３に示すように、第二燃焼の基本供給燃料量Ｑｂの範囲において、例えば、五つに分割された領域毎に学習する必要がある。   Next, the routine proceeds to step 107 where the actual supply fuel amount Q ′ is calculated based on the air-fuel ratio of the exhaust gas in the vicinity of the theoretical air-fuel ratio detected by the air-fuel ratio sensor 12 in the first combustion at this time, and the basic supply fuel The ratio Q / Q ′ between the amount and the actual supplied fuel amount Q ′ is learned as the second fuel injection correction coefficient k2n. As shown in FIG. 3, the second fuel injection correction coefficient k2n needs to be learned, for example, for each of the five divided areas in the range of the basic supply fuel amount Qb for the second combustion.

ステップ１０８では、五つの第二燃料噴射補正係数ｋ２ｎが全て学習されたか否かが判断され、この判断が否定される時には、フラグＦは０のまま終了する。それにより、第二燃焼の運転領域において、ステップ１０５からステップ１０７が繰り返され、その間で、機関負荷及び機関回転数の変化により基本供給燃料量Ｑが変化して、別の領域の第二燃料噴射補正係数ｋ２ｎが学習され、遂には、各領域の全ての第二燃料噴射補正係数ｋ２ｎが学習される。この時には、ステップ１０８の判断は肯定され、ステップ１０９において、フラグＦは１とされる。   In step 108, it is determined whether or not all of the five second fuel injection correction coefficients k2n have been learned. When this determination is negative, the flag F remains 0. Accordingly, Step 105 to Step 107 are repeated in the operation region of the second combustion, during which the basic supply fuel amount Q changes due to changes in the engine load and the engine speed, and the second fuel injection in another region. The correction coefficient k2n is learned, and finally all the second fuel injection correction coefficients k2n in each region are learned. At this time, the determination in step 108 is affirmed and the flag F is set to 1 in step 109.

その結果、第二燃焼での運転領域において、ステップ１０２の判断は肯定されるようになり、ステップ１０３において、機関負荷と機関回転数等とに基づく理論空燃比運転に必要な基本供給燃料量Ｑｂに、燃焼空燃比をリーン空燃比とするための減量補正係数ａ（１より小さな正値）と第二燃料噴射補正係数ｋ２ｎとが乗算されて供給燃料量Ｑが算出される。次いで、ステップ１０４において、第二燃焼の第二燃料噴射割合（例えば、３：７）に基づき供給燃料量Ｑを気筒内へ供給するために、第一燃料噴射弁１４及び第二燃料噴射弁１５のそれぞれの燃料噴射量が設定され、第二燃焼が実施される。すなわち、第二燃焼のために減量補正された基本燃料供給量Ｑｂ・ａを第二燃料噴射割合で噴射するための第一燃料噴射弁１４及び第二燃料噴射弁１５のそれぞれの燃料噴射量が、空燃比センサ１２の出力に基づきフィードバック補正されることなく、第二燃料噴射補正係数ｋ２ｎによって補正されることとなる。ここで、気筒内へ供給されるべき必要供給燃料量は、減量補正された基本供給燃料量Ｑｂ・ａであり、第二燃料噴射補正係数ｋ２ｎは、減量補正された基本燃料供給量Ｑｂ・ａに対応する領域の第二燃料噴射補正係数が選択される。   As a result, in the operation region in the second combustion, the determination in step 102 becomes affirmative, and in step 103, the basic supply fuel amount Qb necessary for the theoretical air-fuel ratio operation based on the engine load, the engine speed, and the like. Further, the supply fuel amount Q is calculated by multiplying the reduction correction coefficient a (a positive value smaller than 1) for making the combustion air-fuel ratio a lean air-fuel ratio and the second fuel injection correction coefficient k2n. Next, in step 104, the first fuel injection valve 14 and the second fuel injection valve 15 are supplied in order to supply the supplied fuel amount Q into the cylinder based on the second fuel injection ratio (for example, 3: 7) of the second combustion. The respective fuel injection amounts are set, and the second combustion is performed. That is, the respective fuel injection amounts of the first fuel injection valve 14 and the second fuel injection valve 15 for injecting the basic fuel supply amount Qb · a corrected for reduction for the second combustion at the second fuel injection ratio are as follows. The second fuel injection correction coefficient k2n is corrected without feedback correction based on the output of the air-fuel ratio sensor 12. Here, the required supply fuel amount to be supplied into the cylinder is the basic supply fuel amount Qb · a corrected for reduction, and the second fuel injection correction coefficient k2n is the basic fuel supply amount Qb · a after correction for reduction. The second fuel injection correction coefficient in the region corresponding to is selected.

ところで、理論空燃比の第一燃焼時の排気ガスは、三元触媒装置１１により良好に浄化される。一方、リーン空燃比の第二燃焼時の排気ガス中のＮＯXは、ＮＯX吸蔵還元触媒装置１０により吸蔵される。しかしながら、ＮＯX吸蔵還元触媒装置１０は、無制限にＮＯXを吸蔵することはできず、ＮＯX吸蔵量が最大吸蔵可能量に達する以前に吸蔵ＮＯXを放出させて還元浄化する再生処理が必要となる。このような再生処理は、排気ガスの空燃比をリッチにすることにより実現され、そのためには、燃焼空燃比を所望リッチ空燃比とするリッチスパイクが実施される。 By the way, the exhaust gas during the first combustion at the stoichiometric air-fuel ratio is well purified by the three-way catalyst device 11. On the other hand, NO X in the exhaust gas at the time of the second combustion with the lean air-fuel ratio is stored by the NO X storage reduction catalyst device 10. However, the NO X storage reduction catalyst device 10 cannot store NO X indefinitely, and a regeneration process for reducing and purifying the stored NO X before the NO X storage amount reaches the maximum storable amount is necessary. It becomes. Such regeneration processing is realized by making the air-fuel ratio of the exhaust gas rich, and for this purpose, rich spike is performed in which the combustion air-fuel ratio is the desired rich air-fuel ratio.

空燃比センサ１２は、リッチスパイクのようなリッチ空燃比も正確に検出することはできず、それにより、リッチスパイク時の燃料噴射量に空燃比センサ１２の出力に基づくフィードバック補正を実施することはできない。リッチスパイクが実施される時は、ＮＯX吸蔵還元触媒装置１０の推定吸蔵ＮＯX量が設定量に達した時であり、リーン空燃比の第二燃焼時であることが多い。こうして、リッチスパイクを実施する時には、ステップ１０３において、燃焼空燃比をリッチするために、基本供給燃料量Ｑｂには、減量補正係数ａに代えて、増量補正係数ｂ（１より大きな値）が乗算されると共に、第二燃料噴射補正係数ｋ２ｎが乗算されて供給燃料量Ｑを算出すれば良い。 The air-fuel ratio sensor 12 cannot accurately detect a rich air-fuel ratio such as a rich spike, so that feedback correction based on the output of the air-fuel ratio sensor 12 is performed on the fuel injection amount at the time of the rich spike. Can not. The rich spike is performed when the estimated stored NO X amount of the NO X storage reduction catalyst device 10 reaches a set amount, often during the second combustion of the lean air-fuel ratio. Thus, when performing the rich spike, in step 103, in order to enrich the combustion air-fuel ratio, the basic supply fuel amount Qb is multiplied by an increase correction coefficient b (a value greater than 1) instead of the decrease correction coefficient a. In addition, the supplied fuel amount Q may be calculated by multiplying by the second fuel injection correction coefficient k2n.

リッチスパイクは、第二燃焼での運転領域において、第二燃焼の第二燃料噴射割合（例えば、３：７）に基づき供給燃料量Ｑを気筒内へ供給するものであり、第一燃料噴射弁１４及び第二燃料噴射弁１５のそれぞれの燃料噴射量が設定され、リッチ空燃比での燃焼が実施される。すなわち、リッチ空燃比の燃焼のために増量補正された基本燃料供給量Ｑｂ・ｂを第二燃料噴射割合で噴射するための第一燃料噴射弁１４及び第二燃料噴射弁１５のそれぞれの燃料噴射量が、空燃比センサ１２の出力に基づきフィードバック補正されることなく、第二燃料噴射補正係数ｋ２ｎによって補正されることとなる。ここで、気筒内へ供給されるべき必要供給燃料量は、増量補正された基本供給燃料量Ｑｂ・ｂであり、第二燃料噴射補正係数ｋ２ｎは、増量補正された基本燃料供給量Ｑｂ・ｂに対応する領域の第二燃料噴射補正係数が選択される。このように、ステップ１０７において学習された第二燃料噴射補正係数ｋ２ｎは、リーン空燃比での第二燃焼時だけでなく、リッチスパイク時にも使用することができる。   The rich spike is for supplying the supplied fuel amount Q into the cylinder based on the second fuel injection ratio (for example, 3: 7) of the second combustion in the operation region of the second combustion. 14 and the second fuel injection valve 15 are set, and combustion at a rich air-fuel ratio is performed. That is, the fuel injection of each of the first fuel injection valve 14 and the second fuel injection valve 15 for injecting the basic fuel supply amount Qb · b that has been increased and corrected for the rich air-fuel ratio combustion at the second fuel injection ratio. The amount is corrected by the second fuel injection correction coefficient k2n without being feedback-corrected based on the output of the air-fuel ratio sensor 12. Here, the required amount of fuel to be supplied into the cylinder is the basic supply fuel amount Qb · b that has been corrected for increase, and the second fuel injection correction coefficient k2n is the basic fuel supply amount Qb · b that has been corrected for increase. The second fuel injection correction coefficient in the region corresponding to is selected. Thus, the second fuel injection correction coefficient k2n learned in step 107 can be used not only during the second combustion at the lean air-fuel ratio but also during the rich spike.

本実施形態において、全ての学習領域の第二燃料噴射補正係数ｋ２ｎが学習されるまでは、第二燃焼の運転領域において第二燃焼を実施しないようにしたが、もちろん、既に第二燃料噴射補正係数が学習された学習領域においては、学習された第二燃料噴射補正係数を使用して第二燃料噴射割合での第二燃焼を実施するようにしても良い。   In the present embodiment, the second combustion is not performed in the second combustion operation region until the second fuel injection correction coefficient k2n of all the learning regions is learned. In the learning region in which the coefficient is learned, the second combustion at the second fuel injection ratio may be performed using the learned second fuel injection correction coefficient.

本実施形態において、必要供給燃料量に基づく燃料噴射補正係数の学習領域は、第一燃焼の運転領域において三つに、第二燃焼の運転領域において五つに分割したが、これは本発明を限定するものではない。第一燃料噴射弁１４及び第二燃料噴射弁１５の共通の燃料噴射補正係数は、厳密には、必要供給燃料量毎に異なる値となるために、各運転領域をさらに細分化して学習領域をさらに小さな必要供給燃料量の範囲とすることにより、各燃料噴射補正係数をさらに正確なものとすることができる。   In the present embodiment, the learning region of the fuel injection correction coefficient based on the required supply fuel amount is divided into three in the first combustion operation region and five in the second combustion operation region. It is not limited. Strictly speaking, since the common fuel injection correction coefficient for the first fuel injection valve 14 and the second fuel injection valve 15 has a different value for each required amount of supplied fuel, each operation region is further subdivided into a learning region. Each fuel injection correction coefficient can be made more accurate by setting the required fuel supply amount range to be smaller.

燃料噴射補正係数は、第一燃料噴射弁１４及び第二燃料噴射弁１５の燃料噴射割合に係わらず、必要供給燃料量毎に異なる値である。前述の実施形態では、第一燃焼の第一燃料噴射割合と第二燃焼の第二燃料噴射割合とは、異なるものとしたが、第二燃焼の燃焼空燃比が理論空燃比でなく、燃料噴射補正係数を学習することができなければ、第一燃料噴射割合と第二燃料噴射割合とが同一であっても本願発明は有効である。   The fuel injection correction coefficient is a different value for each required fuel supply amount regardless of the fuel injection ratios of the first fuel injection valve 14 and the second fuel injection valve 15. In the above-described embodiment, the first fuel injection ratio of the first combustion and the second fuel injection ratio of the second combustion are different, but the combustion air-fuel ratio of the second combustion is not the stoichiometric air-fuel ratio, and the fuel injection If the correction coefficient cannot be learned, the present invention is effective even if the first fuel injection ratio and the second fuel injection ratio are the same.

本実施形態において、リッチスパイク時の燃料噴射割合は、第二燃焼時の第二燃料噴射割合と同じとしたために、リッチスパイク時の燃料噴射量の補正に第二燃料噴射割合に対して学習された第二燃料噴射補正係数ｋ２ｎを使用している。もちろん、リッチスパイク時の第一燃料噴射弁及び第二燃料噴射弁の燃料噴射割合が、第二燃料噴射割合と異なるものであるならば、リッチスパイク時に第二燃料噴射補正係数ｋ２ｎを使用することはできず、リッチスパイク時の供給燃料量の範囲において、リッチスパイク時の燃料噴射割合により第一燃料噴射弁及び第二燃料噴射弁のそれぞれの燃料噴射量を設定して、第一燃焼を実施することにより、要求供給燃料量に基づく学習領域毎にリッチスパイク時の燃料噴射補正係数を学習すれば良い。また、本実施形態において、第二燃料噴射補正係数ｋ２ｎの学習は、機関始動直後に実施するようにしたが、これは本発明を限定するものではなく、実施期間は任意に設定可能である。   In the present embodiment, since the fuel injection ratio at the time of rich spike is the same as the second fuel injection ratio at the time of second combustion, the fuel injection amount at the time of rich spike is corrected with respect to the second fuel injection ratio. The second fuel injection correction coefficient k2n is used. Of course, if the fuel injection ratios of the first fuel injection valve and the second fuel injection valve during the rich spike are different from the second fuel injection ratio, the second fuel injection correction coefficient k2n should be used during the rich spike. In the range of the amount of fuel supplied at the time of rich spike, the first fuel injection amount of each of the first fuel injection valve and the second fuel injection valve is set according to the fuel injection ratio at the time of rich spike, and the first combustion is performed. Thus, the fuel injection correction coefficient at the time of rich spike may be learned for each learning region based on the required supply fuel amount. In the present embodiment, the learning of the second fuel injection correction coefficient k2n is performed immediately after the engine is started. However, this does not limit the present invention, and the implementation period can be arbitrarily set.

本発明による燃料噴射制御装置が取り付けられる内燃機関を示す概略図である。It is the schematic which shows the internal combustion engine to which the fuel-injection control apparatus by this invention is attached. 本発明による燃料噴射制御装置により実施される燃料噴射制御を示すフローチャートである。It is a flowchart which shows the fuel-injection control implemented by the fuel-injection control apparatus by this invention. 図２のフローチャートにおいて使用される学習領域のマップである。It is a map of the learning area | region used in the flowchart of FIG.

符号の説明Explanation of symbols

１ 機関本体
１４ 第一燃料噴射弁
１５ 第二燃料噴射弁 1 Engine Body 14 First Fuel Injection Valve 15 Second Fuel Injection Valve

Claims (2)

気筒内へ燃料を噴射する第一燃料噴射弁と吸気ポートへ燃料を噴射する第二燃料噴射弁とを具備し、前記第一燃料噴射弁と前記第二燃料噴射弁との両方を使用して気筒内へ燃料を供給し、燃焼空燃比を理論空燃比近傍とし、前記第一燃料噴射弁及び前記第二燃料噴射弁の燃料噴射割合を第一燃料噴射割合とする第一燃焼と、燃焼空燃比をリーン空燃比又はリッチ空燃比とするために、理論空燃比を実現する基本燃料供給量を減量補正又は増量補正し、前記第一燃料噴射弁及び前記第二燃料噴射弁の燃料噴射割合を第二燃料噴射割合とする第二燃焼とを切り換えて実施する内燃機関の燃料噴射制御装置において、前記第二燃焼時には、前記第一燃料噴射弁から噴射される燃料噴射量及び前記第二燃料噴射弁から噴射される燃料噴射量が、現在の前記基本燃料供給量の領域における同一の燃料噴射補正係数により補正され、前記燃料噴射補正係数は、前記第二燃焼が実施されるときに、前記基本燃料供給量が気筒内へ供給されるように燃料噴射割合を前記第二燃料噴射割合として前記第一燃料噴射弁の燃料噴射量及び前記第二燃料噴射弁の燃料噴射量を設定して燃料噴射を実施した場合の前記基本燃料供給量と実際に気筒内へ供給された供給燃料量との比として、前記基本燃料供給量に基づき分割された前記領域毎に学習されることを特徴とする内燃機関の燃料噴射制御装置。 A first fuel injection valve for injecting fuel into the cylinder and a second fuel injection valve for injecting fuel into the intake port, and using both the first fuel injection valve and the second fuel injection valve Fuel is supplied into the cylinder, the combustion air-fuel ratio is in the vicinity of the stoichiometric air-fuel ratio, the first combustion injection ratio of the first fuel injection valve and the second fuel injection valve is the first fuel injection ratio, In order to obtain a lean air-fuel ratio or a rich air-fuel ratio, the basic fuel supply amount that achieves the stoichiometric air-fuel ratio is corrected to decrease or increase, and the fuel injection ratios of the first fuel injection valve and the second fuel injection valve are set. In a fuel injection control device for an internal combustion engine that performs switching between second combustion with a second fuel injection ratio, the amount of fuel injected from the first fuel injection valve and the second fuel injection during the second combustion The amount of fuel injected from the valve The fuel injection correction coefficient is corrected by the same fuel injection correction coefficient in the region of the basic fuel supply amount so that the basic fuel supply amount is supplied into the cylinder when the second combustion is performed. The basic fuel supply amount and the actual amount when the fuel injection is performed by setting the fuel injection amount of the first fuel injection valve and the fuel injection amount of the second fuel injection valve with the fuel injection ratio as the second fuel injection ratio A fuel injection control device for an internal combustion engine, which is learned for each of the regions divided based on the basic fuel supply amount as a ratio to the amount of fuel supplied to the cylinder . 前記第二燃焼時の前記第一燃料噴射弁及び前記第二燃料噴射弁の燃料噴射量は、空燃比センサの出力に基づくフィードバック補正が実施されることなく、学習された前記燃料噴射補正係数により補正されることを特徴とする請求項１に記載の内燃機関の燃料噴射制御装置。   The fuel injection amounts of the first fuel injection valve and the second fuel injection valve during the second combustion are determined by the learned fuel injection correction coefficient without performing feedback correction based on the output of the air-fuel ratio sensor. The fuel injection control device for an internal combustion engine according to claim 1, wherein the fuel injection control device is corrected.
JP2006051681A 2006-02-28 2006-02-28 Fuel injection control device for internal combustion engine Expired - Fee Related JP4337831B2 (en)

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JP2006051681A JP4337831B2 (en) 2006-02-28 2006-02-28 Fuel injection control device for internal combustion engine
CN2007800014642A CN101365871B (en) 2006-02-28 2007-02-26 Fuel injection control apparatus and control method of internal combustion engine
EP07713064.9A EP1989430B1 (en) 2006-02-28 2007-02-26 Fuel injection control apparatus and control method of internal combustion engine
US12/085,833 US7653475B2 (en) 2006-02-28 2007-02-26 Fuel injection control apparatus and control method of internal combustion engine
PCT/IB2007/000449 WO2007099425A1 (en) 2006-02-28 2007-02-26 Fuel injection control apparatus and control method of internal combustion engine

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