JP2005171826A - Fuel injection control device of internal combustion engine - Google Patents

Fuel injection control device of internal combustion engine Download PDF

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JP2005171826A
JP2005171826A JP2003411024A JP2003411024A JP2005171826A JP 2005171826 A JP2005171826 A JP 2005171826A JP 2003411024 A JP2003411024 A JP 2003411024A JP 2003411024 A JP2003411024 A JP 2003411024A JP 2005171826 A JP2005171826 A JP 2005171826A
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fuel injection
injection amount
internal combustion
combustion engine
control device
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JP4329520B2 (en
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Jun Maemura
純 前村
Masanao Idogawa
正直 井戸側
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Toyota Motor Corp
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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
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device of a direct injection internal combustion engine, capable of performing effective divided injection, by surely securing its function on respective injections of the divided injection. <P>SOLUTION: A control part 30 of the internal combustion engine divides a fuel injection quantity set on the basis of an engine operation state into an intake stroke and a compression stroke on the basis of the predetermined injection quantity ratio. The control part 30 sets a lower limit value on a compression stroke injection quantity among these intake stroke injection quantity and compression stroke injection quantity; equally sets the compression stroke injection quantity and the lower limit value when the compression stroke injection quantity is less than its lower limit value; and reduces a difference of these (a difference between the compression stroke injection quantity and the lower limit value) from the intake stroke injection quantity. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

機関運転状態に基づいて設定される燃料噴射量を所定の噴射量比率に基づいて吸気行程及び圧縮行程に分割する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 that divides a fuel injection amount set based on an engine operating state into an intake stroke and a compression stroke based on a predetermined injection amount ratio.

一般に、内燃機関の始動に際しては通常運転時と比較して燃料噴射量を増量することによりその始動性を向上させるようにしている。そしてこの場合、例えば特許文献１や特許文献２等にみられるように、始動時或いは始動後所定期間に必要とされる燃料を一度に噴射するのではなく、これを例えば吸気行程と圧縮行程とに分けて噴射する、いわゆる分割噴射が従来より行われている。このように燃料を分割して噴射することにより、例えば吸気行程に燃料を噴射することにより混合気の均質性を圧縮行程に先立ち高めておくことができ、またこれに続く圧縮行程の燃料噴射により点火プラグ近傍に燃料濃度の高い混合気層、いわば火種を形成することができる。その結果、混合気の着火性を高めつつ、その後の安定した混合気の燃焼、ひいては機関始動性の向上を図ることができるようになる。
特開２００３−３２８８１６号公報 特開平１１−３６９１９号公報 Generally, when starting an internal combustion engine, the startability is improved by increasing the fuel injection amount as compared with that during normal operation. In this case, as shown in, for example, Patent Document 1 and Patent Document 2, the fuel required at the time of start-up or a predetermined period after the start-up is not injected at once, but this is, for example, an intake stroke and a compression stroke. So-called divided injection, in which injection is performed separately, is conventionally performed. By dividing and injecting the fuel in this way, for example, by injecting the fuel in the intake stroke, the homogeneity of the air-fuel mixture can be increased prior to the compression stroke, and by the fuel injection in the subsequent compression stroke An air-fuel mixture layer having a high fuel concentration, that is, a fire type can be formed in the vicinity of the spark plug. As a result, while improving the ignitability of the air-fuel mixture, the subsequent stable combustion of the air-fuel mixture, and hence the engine startability can be improved.
JP 2003-328816 A Japanese Patent Laid-Open No. 11-36919

但し、こうした分割噴射は吸気行程及び圧縮行程での燃料噴射がその意図する機能を発揮してはじめて意味を持つものとなる。例えば、機関始動に際して増量された燃料噴射量を徐々に減量していく場合、その減量に伴って圧縮行程に噴射される燃料の量が過度に少なくなると、もはや火種としての機能を失ってしまい、着火性の低下、ひいては機関始動性の悪化を招くこととなる。また、吸気行程に噴射される燃料の量についても同様に、これが過度に少なくなると、混合気の均質性が低下し、混合気の着火性は確保されるものの、その後の安定した燃焼は望めなくなる。また、こうした不都合は機関始動時に顕著にみられるが、通常運転時に実行される分割噴射についても概ね共通したものといえる。   However, such split injection becomes meaningful only when the fuel injection in the intake stroke and the compression stroke performs its intended function. For example, when the fuel injection amount increased at the time of starting the engine is gradually decreased, if the amount of fuel injected in the compression stroke is excessively reduced along with the decrease, the function as a fire type is lost. Decrease in ignitability, and consequently deterioration in engine startability. Similarly, when the amount of fuel injected in the intake stroke is excessively reduced, the homogeneity of the air-fuel mixture decreases and the ignitability of the air-fuel mixture is ensured, but subsequent stable combustion cannot be expected. . Although such inconvenience is noticeable when the engine is started, it can be said that the divided injection that is executed during normal operation is also generally common.

因みに、こうした分割噴射の代表例として、メイン噴射に先立ちパイロット噴射を行うものがあり、これは特にディーゼル機関の燃焼騒音を低減するための噴射方式として多用されている。そしてこの場合、パイロット噴射での燃料噴射量指令値が燃料噴射弁の最小燃料噴射量を下回る場合には、通常、パイロット噴射を停止するか或いはパイロット噴射量をその最小燃料噴射量以下にならないよう制限している。但し、これは燃料噴射弁の機械的応答性により定まる最小燃料噴射量以下の燃料噴射量を噴射することができないために燃料噴射量を制限するものであり、本発明が課題とするような分割噴射における各噴射の機能に着目したものとは本質的に異なる。   Incidentally, as a typical example of such split injection, there is one in which pilot injection is performed prior to main injection, and this is particularly frequently used as an injection method for reducing combustion noise of a diesel engine. In this case, when the fuel injection amount command value in the pilot injection is lower than the minimum fuel injection amount of the fuel injection valve, the pilot injection is usually stopped or the pilot injection amount is not reduced below the minimum fuel injection amount. Restricted. However, this limits the fuel injection amount because the fuel injection amount below the minimum fuel injection amount determined by the mechanical responsiveness of the fuel injection valve cannot be injected. This is essentially different from that focusing on the function of each injection.

この発明は、こうした従来の実情に鑑みてなされたものであり、その目的は分割噴射の各噴射についてその機能を確実に確保して効果的な分割噴射を実行することのできる直噴内燃機関の燃料噴射制御装置を提供することにある。   The present invention has been made in view of such conventional circumstances, and an object of the present invention is to provide a direct-injection internal combustion engine capable of executing effective split injection while ensuring the function of each split injection. A fuel injection control device is provided.

以下、上記課題を達成するための手段並びにその作用効果について説明する。
請求項１記載の発明は、機関運転状態に基づいて設定される燃料噴射量を所定の噴射量比率に基づいて吸気行程及び圧縮行程に分割する燃料噴射制御手段を備える直噴内燃機関の燃料噴射制御装置において、前記燃料噴射制御手段は前記噴射量比率に基づいて可変設定される前記吸気行程の燃料噴射量及び前記圧縮行程の燃料噴射量の少なくとも一方について下限値を設定し、その一方の燃料噴射量が前記下限値を下回るときに前記一方の燃料噴射量と前記下限値とを等しく設定するとともにそれらの差分（前記一方の燃料噴射量と前記下限値との差分）を前記可変設定される他方の燃料噴射量から減量するものであるとしている。 Hereinafter, the means for achieving the above-described problems and the effects thereof will be described.
According to a first aspect of the present invention, a fuel injection of a direct injection internal combustion engine comprising a fuel injection control means for dividing a fuel injection amount set based on an engine operating state into an intake stroke and a compression stroke based on a predetermined injection amount ratio. In the control device, the fuel injection control means sets a lower limit value for at least one of the fuel injection amount of the intake stroke and the fuel injection amount of the compression stroke, which is variably set based on the injection amount ratio, When the injection amount falls below the lower limit value, the one fuel injection amount and the lower limit value are set equal and the difference between them (the difference between the one fuel injection amount and the lower limit value) is variably set. The amount is reduced from the other fuel injection amount.

同構成によれば燃料を所定の噴射量比率に基づいて吸気行程及び圧縮行程に分割して噴射する際に、各燃料噴射量がそれらに対応して設定された下限値を下回ることのないように制限される。従って、その制限される行程での燃料噴射は少なくとも下限値以上の噴射量をもって行われるようになり、各行程での噴射についてその機能を確実に確保して効果的な分割噴射を実行することができるようになる。   According to this configuration, when fuel is injected by being divided into an intake stroke and a compression stroke based on a predetermined injection amount ratio, each fuel injection amount does not fall below a lower limit value set corresponding thereto. Limited to Therefore, fuel injection in the restricted stroke is performed with an injection amount at least equal to or lower than the lower limit, and it is possible to execute effective divided injection while ensuring the function of the injection in each stroke. become able to.

特に、こうした分割噴射に際しての燃料噴射量について下限値を設定することは、請求項２記載の発明によるように、機関始動に際しての燃料噴射量増量がなされるとき、すなわち機関燃焼状態が不安定な傾向にあるときにその極めて有効である。   In particular, setting the lower limit value for the fuel injection amount at the time of such divided injection is that when the fuel injection amount is increased at the time of starting the engine, that is, the engine combustion state is unstable, as in the second aspect of the invention. It is extremely effective when there is a tendency.

更に、こうした機関始動に際して分割噴射を行う場合には、請求項３記載の発明によるように、請求項２記載の発明において、圧縮行程の燃料噴射量が吸気行程の燃料噴射量よりも少なくなるように噴射量比率を設定することにより、吸気行程噴射により混合気の均質性を圧縮行程に先立ち高め、またこれに続く圧縮行程噴射により点火プラグ近傍に燃料濃度の高い混合気層、いわば火種を形成することができるようになるため、機関始動性を向上させるとともに、機関燃焼状態を安定化させる上で望ましい。   Further, when split injection is performed at the time of starting the engine, as in the invention described in claim 3, in the invention described in claim 2, the fuel injection amount in the compression stroke is smaller than the fuel injection amount in the intake stroke. By setting the injection amount ratio, the intake stroke injection increases the homogeneity of the air-fuel mixture prior to the compression stroke, and the subsequent compression stroke injection forms a mixture layer with a high fuel concentration in the vicinity of the spark plug, that is, a so-called fire type. Therefore, it is desirable to improve the engine startability and stabilize the engine combustion state.

請求項４記載の発明は、請求項３記載の直噴内燃機関の燃料噴射制御装置において、前記燃料噴射制御手段は前記可変設定される圧縮行程の燃料噴射量について下限値を設定し、同圧縮行程の燃料噴射量が前記下限値を下回るときにこれらを等しく設定するとともにそれらの差分を前記可変設定される吸気行程の燃料噴射量から減量するものであるとしている。   According to a fourth aspect of the present invention, in the fuel injection control device for a direct injection internal combustion engine according to the third aspect, the fuel injection control means sets a lower limit value for the fuel injection amount of the compression stroke that is variably set. When the fuel injection amount in the stroke falls below the lower limit value, they are set equal, and the difference between them is reduced from the fuel injection amount in the intake stroke that is variably set.

同構成によれば、機関始動に際して火種として機能する圧縮行程での燃料噴射量が確保されるようになるため、機関始動性を一層高めることができるようになる。
ところで、こうした圧縮行程噴射を行う場合にあって、同噴射により噴射される燃料を火種として十分に機能させるためには、点火プラグによる点火時期についても併せて考慮する必要があり、具体的には、圧縮行程で噴射された燃料が点火プラグの近傍に偏在している期間に点火時期を設定する必要がある。このため分割噴射の実行中は点火時期については自ずと制限を受けることとなる。一般に、点火時期はこれを進角させることで機関出力の向上を図ることができるが、こうした制限下では点火時期の進角を行うことが困難になり、機関出力についても制限されるようになる。 According to this configuration, the fuel injection amount in the compression stroke that functions as a fire type when starting the engine is secured, so that the engine startability can be further improved.
By the way, in the case of performing such compression stroke injection, in order to sufficiently function the fuel injected by the injection as a fire type, it is necessary to consider the ignition timing by the spark plug, specifically, It is necessary to set the ignition timing in a period in which the fuel injected in the compression stroke is unevenly distributed in the vicinity of the spark plug. For this reason, the ignition timing is naturally restricted during execution of split injection. In general, it is possible to improve the engine output by advancing the ignition timing, but under such restrictions, it becomes difficult to advance the ignition timing, and the engine output is also limited. .

そこで、請求項５記載の発明は、請求項４記載の直噴内燃機関の燃料噴射制御装置において、前記燃料噴射制御手段は機関回転速度を監視し、同監視される機関回転速度が所定値以上に上昇したことを条件に前記噴射量比率による分割噴射を停止して吸気行程のみの燃料噴射を許可するものであるとしている。   Accordingly, the invention according to claim 5 is the fuel injection control device for a direct injection internal combustion engine according to claim 4, wherein the fuel injection control means monitors the engine rotational speed, and the monitored engine rotational speed is a predetermined value or more. On the condition that the fuel injection rate is increased, the fuel injection in only the intake stroke is permitted by stopping the divided injection based on the injection amount ratio.

また、請求項６記載の発明は、請求項４記載の直噴内燃機関の燃料噴射制御装置において、前記燃料噴射制御手段は燃料噴射量が所定量未満であることを条件に前記噴射量比率による分割噴射を停止して吸気行程のみの燃料噴射を許可するものであるとしている。   According to a sixth aspect of the present invention, in the fuel injection control device for a direct injection internal combustion engine according to the fourth aspect, the fuel injection control means depends on the injection amount ratio on condition that the fuel injection amount is less than a predetermined amount. The split injection is stopped and fuel injection only in the intake stroke is permitted.

機関始動に際して機関回転速度が所定回転数以上にまで上昇した場合には、内燃機関が自立運転可能な状態となっており（請求項５）、また、燃焼噴射量が所定量未満にまで低下した場合には、燃料噴射量の増量が終了しつつあり、燃焼状態が既に安定状態に移行している（請求項６）。このため、これら請求項５又は請求項６記載の各構成では、こうした場合に分割噴射を停止して吸気行程のみの燃料噴射を許可するようにしている。このように、吸気行程のみの燃料噴射が許可されて圧縮行程噴射が停止されると、上述したような点火時期の制限がなくなるため、これを進角させることによりそれに基づく機関出力の向上を図ることができるようになる。   When the engine speed increases to a predetermined rotational speed or more when starting the engine, the internal combustion engine is in a state where it can operate independently (Claim 5), and the combustion injection amount is reduced to a value less than the predetermined amount. In this case, the increase in the fuel injection amount is ending, and the combustion state has already shifted to the stable state (Claim 6). For this reason, in each of the configurations described in claims 5 and 6, in such a case, the divided injection is stopped and the fuel injection only in the intake stroke is permitted. As described above, when the fuel injection only in the intake stroke is permitted and the compression stroke injection is stopped, the ignition timing is not limited as described above, so that the engine output is improved by advancing this. Will be able to.

以下、本発明をＶ型の気筒配列を有した６気筒内燃機関の燃料噴射制御装置に適用した例について図面を参照して説明する。
図１はこの例にかかる燃料噴射制御装置を示している。内燃機関の各気筒１０（図１ではその一つのみを示す）内には機関ピストン１３が設けられており、同機関ピストン１３の上方に燃焼室１１が区画形成されている。各気筒１０にはそれぞれ燃料噴射弁１４が設けられており、同燃料噴射弁１４の先端部に形成された噴孔（図示略）から燃焼室１１内に燃料が直接噴射供給される。燃焼室１１には吸気通路１８及び排気通路１９が接続されている。また、各気筒１０には、吸気通路１８を通じて燃焼室１１に導入される吸入空気と混合された燃料、すなわち混合気に着火する点火プラグ１６が設けられている。 Hereinafter, an example in which the present invention is applied to a fuel injection control device for a six-cylinder internal combustion engine having a V-type cylinder arrangement will be described with reference to the drawings.
FIG. 1 shows a fuel injection control apparatus according to this example. An engine piston 13 is provided in each cylinder 10 (only one of which is shown in FIG. 1) of the internal combustion engine, and a combustion chamber 11 is defined above the engine piston 13. Each cylinder 10 is provided with a fuel injection valve 14, and fuel is directly injected into the combustion chamber 11 from an injection hole (not shown) formed at the tip of the fuel injection valve 14. An intake passage 18 and an exhaust passage 19 are connected to the combustion chamber 11. Each cylinder 10 is provided with a spark plug 16 that ignites the fuel mixed with the intake air introduced into the combustion chamber 11 through the intake passage 18, that is, the air-fuel mixture.

内燃機関は、燃料噴射制御や点火時期制御等、機関にかかる制御を統括して実行する制御部３０を備えている。この制御部３０には、機関冷却水温を検出する水温センサ２０、機関回転速度及びクランク角を検出する回転速度センサ２１、並びに吸入空気量を検出する吸入空気量センサ２２等々、各種センサがそれぞれ接続されている。制御部３０はそれらセンサの検出信号を取り込み、それら検出信号に基づいて適宜演算処理を行うことにより、燃料噴射制御等、各種の機関制御を実行する。   The internal combustion engine includes a control unit 30 that performs overall control of the engine such as fuel injection control and ignition timing control. Various sensors such as a water temperature sensor 20 for detecting the engine cooling water temperature, a rotation speed sensor 21 for detecting the engine rotation speed and the crank angle, and an intake air amount sensor 22 for detecting the intake air amount are connected to the control unit 30. Has been. The control unit 30 executes various engine controls such as fuel injection control by taking in the detection signals of these sensors and appropriately performing arithmetic processing based on the detection signals.

以下、こうした制御部３０により実行される各種制御のうち、機関始動時の燃料噴射制御について説明する。本例では機関始動に際して燃料を吸気行程と圧縮行程とに分割して噴射する分割噴射を行うようにしている。また、吸気行程の燃料噴射量（吸気行程噴射量ＦＩ）及び圧縮行程の燃料噴射量（圧縮行程噴射量ＦＣ）は、

ＦＩ：ＦＣ＝Ｔ・（１−α）：Ｔ・α …（１）
０＜α＜１（例えば０．２）

なる式が満たされるように、所定の噴射量比率αに基づいて可変設定される。 Hereinafter, fuel injection control at the time of engine start will be described among various controls executed by the control unit 30. In this example, when the engine is started, divided injection is performed in which fuel is divided into an intake stroke and a compression stroke. Further, the fuel injection amount in the intake stroke (intake stroke injection amount FI) and the fuel injection amount in the compression stroke (compression stroke injection amount FC) are:

FI: FC = T · (1-α): T · α (1)
0 <α <1 (for example, 0.2)

Is set variably based on a predetermined injection amount ratio α so that the following equation is satisfied.

ところで、機関始動時には、その始動性を向上させ、燃焼状態を安定させるために通常運転時と比較して燃料噴射量の増量がなされる。また、機関燃焼状態は各気筒１０において混合気の燃焼が行われるのに伴って徐々に安定するようになる。このため、図２に示されるように、通常、機関始動開始時（タイミングｔ１）からの時間の経過に伴って燃料噴射量Ｔは徐々に減少するようになる。このように燃料噴射量Ｔが減少する場合にも、吸気行程噴射量ＦＩ及び圧縮行程噴射量ＦＣは上述した式（１）に基づいて算出される。   By the way, when the engine is started, the fuel injection amount is increased as compared with that during normal operation in order to improve the startability and stabilize the combustion state. Further, the engine combustion state gradually becomes stable as the air-fuel mixture is combusted in each cylinder 10. For this reason, as shown in FIG. 2, normally, the fuel injection amount T gradually decreases with the passage of time from the start of engine start (timing t1). Even when the fuel injection amount T decreases in this way, the intake stroke injection amount FI and the compression stroke injection amount FC are calculated based on the above-described equation (1).

但しここで、圧縮行程噴射量ＦＣについてはその下限値ＦＣＭＩＮを設定しており、上式（１）に基づいて設定される圧縮行程噴射量ＦＣがこの下限値ＦＣＭＩＮを下回る場合には、同圧縮行程噴射量ＦＣをこの下限値ＦＣＭＩＮと等しく設定するようにしている。これに加えて、それらの差分、即ち（ＦＣＭＩＮ−ＦＣ）を吸気行程噴射量ＦＩから減量するようにしている。この下限値ＦＣＭＩＮは、圧縮行程で噴射される燃料がそれに引き続き実行される混合気の燃焼の火種として機能するのに十分な量に設定されている。換言すれば、この下限値ＦＣＭＩＮ未満の燃料噴射量をもって圧縮行程噴射を実行したとしても、その実効性は極めて低く、本来の分割噴射の意図とする機能が発揮できないことになる。   However, a lower limit value FCMIN is set for the compression stroke injection amount FC, and if the compression stroke injection amount FC set based on the above equation (1) is less than the lower limit value FCMIN, the same compression is performed. The stroke injection amount FC is set equal to the lower limit value FCMIN. In addition, the difference, that is, (FCMIN-FC) is reduced from the intake stroke injection amount FI. This lower limit value FCMIN is set to an amount sufficient for the fuel injected in the compression stroke to function as a combustion type of the air-fuel mixture that is subsequently executed. In other words, even if the compression stroke injection is executed with the fuel injection amount less than the lower limit value FCMIN, its effectiveness is extremely low, and the function intended for the original split injection cannot be exhibited.

以下、こうした始動時の燃料噴射制御の詳細について説明する。図３はこの燃料噴射制御の処理手順を示すフローチャートである。このフローチャートに示される一連の処理は、本装置にかかる燃料噴射制御手段の一部を構成する制御部３０により実行される。   Details of the fuel injection control at the time of starting will be described below. FIG. 3 is a flowchart showing the processing procedure of this fuel injection control. A series of processing shown in this flowchart is executed by the control unit 30 constituting a part of the fuel injection control means according to the present apparatus.

この一連の処理では、まず機関回転速度及び吸入空気量等に基づいて基本燃料噴射量が算出され、更に機関冷却水温、機関始動開始時からの経過時間等に基づいて始動増量値が算出される。そして、これらを加算して燃料噴射量Ｔが算出される（ステップＳ１００）。因みに、始動増量値は水温が高いほど、また機関始動開始時からの経過時間が長いほど少なく設定される。従って、基本燃料噴射量が一定とすれば、ここで算出される燃料噴射量Ｔは機関始動開始時から徐々に減少するようになる。   In this series of processing, first, the basic fuel injection amount is calculated based on the engine rotational speed, the intake air amount, and the like, and further, the starting increase value is calculated based on the engine cooling water temperature, the elapsed time from the start of engine starting, and the like. . These are added to calculate the fuel injection amount T (step S100). Incidentally, the start increase value is set to be smaller as the water temperature is higher and as the elapsed time from the start of the engine is longer. Therefore, if the basic fuel injection amount is constant, the fuel injection amount T calculated here gradually decreases from the start of engine start.

次に、以下の演算式に基づいて圧縮行程噴射量ＦＣが算出される（ステップＳ１１０）。

ＦＣ←Ｔ・α …（２）

このように圧縮行程噴射量ＦＣが算出されると、次に機関回転速度ＮＥがその判定値ＮＥＭＩＮ未満であり（条件１）、且つ、燃料噴射量Ｔがその判定値ＴＭＩＮを上回っているか（条件２）が判断される（ステップＳ１２０）。ここで、機関回転速度ＮＥにかかる判定値ＮＥＭＩＮは、内燃機関が自立運転可能な状態に移行したか否かを判定し得る値（例えば１２００ｒｐｍ）に設定されている。また、燃料噴射量Ｔにかかる判定値ＴＭＩＮは、機関始動開始時から所定時間が経過して機関燃焼が安定した状態にあることを判定し得る値に設定されている。 Next, the compression stroke injection amount FC is calculated based on the following arithmetic expression (step S110).

FC ← T ・ α (2)

When the compression stroke injection amount FC is calculated in this way, the engine speed NE is next less than the determination value NEMIN (condition 1), and the fuel injection amount T exceeds the determination value TMIN (condition). 2) is determined (step S120). Here, the determination value NEMIN relating to the engine rotational speed NE is set to a value (for example, 1200 rpm) that can determine whether or not the internal combustion engine has shifted to a state where it can operate independently. Further, the determination value TMIN relating to the fuel injection amount T is set to a value that can determine that the engine combustion is in a stable state after a predetermined time has elapsed from the start of the engine start.

ここで、上記各条件１，２のいずれか一方が成立していない場合には（ステップＳ１２０：ＮＯ）、始動時燃料噴射制御から通常運転時燃料噴射制御（ステップＳ２００）に処理が移される。このように、通常運転時燃料噴射制御に処理が移行すると、必要に応じて分割噴射が停止され、吸気行程噴射のみが実行されるようになる。従って、この場合には、上述したような圧縮行程噴射を実行することによる点火時期の制約が無くなり、点火時期を必要に応じて進角させることにより機関出力の向上を図ることができるようになる。   Here, when either one of the above conditions 1 and 2 is not satisfied (step S120: NO), the processing is shifted from the starting fuel injection control to the normal operation fuel injection control (step S200). As described above, when the process shifts to the normal operation fuel injection control, the divided injection is stopped as necessary, and only the intake stroke injection is executed. Therefore, in this case, there is no restriction on the ignition timing by executing the compression stroke injection as described above, and the engine output can be improved by advancing the ignition timing as necessary. .

一方、上記各条件１，２の双方が成立している場合には（ステップＳ１２０：ＹＥＳ）、通常運転時燃料噴射制御に移行することなく始動時燃料噴射制御がそのまま継続される。即ちこの場合には、まず、圧縮行程噴射量ＦＣがその下限値ＦＣＭＩＮを下回っているか否かが判断される（ステップＳ１３０）。ここで、圧縮行程噴射量ＦＣが下限値ＦＣＭＩＮを下回っている場合には（ステップＳ１３０：ＹＥＳ）、圧縮行程噴射量ＦＣを制限すべく、これが下限値ＦＣＭＩＮと等しく設定される（ステップＳ１４０）。一方、圧縮行程噴射量ＦＣが下限値ＦＣＭＩＮ以上である場合には（ステップＳ１３０：ＮＯ）、こうした圧縮行程噴射量ＦＣにかかる制限は行われず、先のステップＳ１１０において算出された圧縮行程噴射量ＦＣの値がそのまま採用される。   On the other hand, when both of the above conditions 1 and 2 are satisfied (step S120: YES), the start time fuel injection control is continued without shifting to the normal operation time fuel injection control. That is, in this case, it is first determined whether or not the compression stroke injection amount FC is below the lower limit value FCMIN (step S130). Here, when the compression stroke injection amount FC is below the lower limit value FCMIN (step S130: YES), this is set equal to the lower limit value FCMIN to limit the compression stroke injection amount FC (step S140). On the other hand, when the compression stroke injection amount FC is equal to or greater than the lower limit value FCMIN (step S130: NO), such a restriction on the compression stroke injection amount FC is not performed, and the compression stroke injection amount FC calculated in the previous step S110. The value of is adopted as it is.

このように圧縮行程噴射量ＦＣの下限値制限処理（ステップＳ１３０、ステップＳ１４０）を実行した後、以下の演算式に基づいて吸気行程噴射量ＦＩが算出される（ステップＳ１５０）。   After performing the lower limit value limiting process (step S130, step S140) of the compression stroke injection amount FC in this way, the intake stroke injection amount FI is calculated based on the following arithmetic expression (step S150).


ＦＩ←Ｔ−ＦＣ …（３）

そして、制御部３０は上記各処理を通じて算出された吸気行程噴射量ＦＩ及び圧縮行程噴射量ＦＣに基づいて燃料噴射弁１４に駆動することにより分割噴射を実行する。
FI ← T-FC (3)

Then, the control unit 30 performs the divided injection by driving the fuel injection valve 14 based on the intake stroke injection amount FI and the compression stroke injection amount FC calculated through the above processes.

本例にかかる装置では上述した燃料噴射制御を通じて以下に記載する作用効果を奏することができる。
・機関始動に際して所定の噴射量比率に基づいて分割噴射を実行するようにし、その噴射量比率に基づいて可変設定される圧縮行程噴射の噴射量がその下限値を下回る場合には、同噴射量と同下限値とを等しく設定するとともにそれらの差分（同噴射量と同下限値との差分）を吸気行程噴射量から減量するようにしている。このため、圧縮行程噴射についてその機能を確実に確保して効果的な分割噴射を実行することができ、機関始動性の向上並びに燃焼状態の安定化を図ることができるようになる。 In the apparatus according to this example, the following effects can be achieved through the fuel injection control described above.
When the engine is started, split injection is executed based on a predetermined injection amount ratio, and if the injection amount of the compression stroke injection that is variably set based on the injection amount ratio falls below the lower limit value, the same injection amount And the same lower limit value are set equal to each other and the difference between them (the difference between the same injection amount and the same lower limit value) is reduced from the intake stroke injection amount. For this reason, it is possible to reliably ensure the function of the compression stroke injection and execute the effective divided injection, thereby improving the engine startability and stabilizing the combustion state.

・また、機関回転速度ＮＥがその判定値ＮＥＭＩＮ以上となった場合、或いは燃料噴射量がその判定値ＴＭＩＮ以下となっている場合には、自立運転が可能となっており、また燃焼状態も安定しているとみなして、始動時燃料噴射制御を通常運転時燃料噴射に切り換えるようにしている。従って、必要に応じて分割噴射を停止させて吸気行程噴射のみを実行することができるようになる。その結果、圧縮行程噴射を実行することによる点火時期の制約を解除し、必要に応じて点火時期を進角させることができ、同進角処理を通じて機関出力の向上を図ることができるようになる。   -In addition, when the engine speed NE is equal to or higher than the determination value NEMIN, or when the fuel injection amount is equal to or lower than the determination value TMIN, the autonomous operation is possible and the combustion state is stable. Therefore, the fuel injection control at the start is switched to the fuel injection at the normal operation. Accordingly, it is possible to stop the divided injection as required and execute only the intake stroke injection. As a result, the restriction on the ignition timing due to the execution of the compression stroke injection can be released, the ignition timing can be advanced as required, and the engine output can be improved through the advance angle processing. .

尚、本例は以下のようにその制御構造の一部を変更して実施することも可能である。
・本例では圧縮行程噴射量についてのみ下限値を設定するようにしたが、吸気行程噴射量、或いは圧縮行程噴射量及び吸気行程噴射量の双方に下限値を設定するようにしてもよい。 In addition, this example can also be implemented by changing a part of the control structure as follows.
In this example, the lower limit value is set only for the compression stroke injection amount. However, the lower limit value may be set for both the intake stroke injection amount or the compression stroke injection amount and the intake stroke injection amount.

・本例では噴射量比率αを一定にした場合を例示したが、例えばこれを機関運転状態に基づいて可変設定するようにしてよい。また、圧縮行程噴射量ＦＣの下限値ＦＣＭＩＮについても同様にこれを機関運転状態に基づいて可変設定するようにしてもよい。   In this example, the case where the injection amount ratio α is constant is illustrated, but this may be variably set based on the engine operating state, for example. Similarly, the lower limit value FCMIN of the compression stroke injection amount FC may be variably set based on the engine operating state.

・本例では、機関回転速度ＮＥがその判定値ＮＥＭＩＮ以上であるか、或いは燃料噴射量Ｔがその判定値ＴＭＩＮ以下であるときに通常運転時燃料噴射制御に切り換えるようにしたが、これら条件の双方が成立したときに通常運転時燃料噴射制御に切り換えるようにしてもよい。   In this example, when the engine speed NE is equal to or higher than the determination value NEMIN or the fuel injection amount T is equal to or lower than the determination value TMIN, the fuel injection control is switched to the normal operation fuel injection control. When both are established, the fuel injection control may be switched to the normal operation fuel injection control.

内燃機関の燃料噴射制御装置の構成図。The block diagram of the fuel-injection control apparatus of an internal combustion engine. 燃料噴射量の推移を示すタイムチャート。The time chart which shows transition of fuel injection amount. 燃料噴射制御についてその処理手順を示すフローチャート。The flowchart which shows the process sequence about fuel-injection control.

符号の説明Explanation of symbols

１０…気筒、１１…燃焼室、１３…機関ピストン、１４…燃料噴射弁、１６…点火プラグ、１８…吸気通路、１９…排気通路、２０…水温センサ、２１…回転速度センサ、２２…吸入空気量センサ、３０…制御部、α…噴射量比率、ＦＣＭＩＮ…下限値、ＮＥ…機関回転速度、Ｔ…燃料噴射量。   DESCRIPTION OF SYMBOLS 10 ... Cylinder, 11 ... Combustion chamber, 13 ... Engine piston, 14 ... Fuel injection valve, 16 ... Spark plug, 18 ... Intake passage, 19 ... Exhaust passage, 20 ... Water temperature sensor, 21 ... Rotation speed sensor, 22 ... Intake air An amount sensor, 30 ... a control unit, α ... an injection amount ratio, FCMIN ... a lower limit value, NE ... an engine speed, T ... a fuel injection amount.

Claims (6)

機関運転状態に基づいて設定される燃料噴射量を所定の噴射量比率に基づいて吸気行程及び圧縮行程に分割する燃料噴射制御手段を備える直噴内燃機関の燃料噴射制御装置において、
前記燃料噴射制御手段は前記噴射量比率に基づいて可変設定される前記吸気行程の燃料噴射量及び前記圧縮行程の燃料噴射量の少なくとも一方について下限値を設定し、その一方の燃料噴射量が前記下限値を下回るときにこれらを等しく設定するとともにそれらの差分を他方の燃料噴射量から減量する
ことを特徴とする直噴内燃機関の燃料噴射制御装置。 In a fuel injection control device for a direct injection internal combustion engine comprising fuel injection control means for dividing a fuel injection amount set based on an engine operating state into an intake stroke and a compression stroke based on a predetermined injection amount ratio,
The fuel injection control means sets a lower limit value for at least one of the fuel injection amount of the intake stroke and the fuel injection amount of the compression stroke, which is variably set based on the injection amount ratio, and the one fuel injection amount is A fuel injection control device for a direct injection internal combustion engine, wherein when the value is below a lower limit value, these are set equal and the difference between them is reduced from the other fuel injection amount. 請求項１記載の直噴内燃機関の燃料噴射制御装置において、
前記燃料噴射制御手段は機関始動に際しての燃料噴射量増量がなされるときに前記噴射量比率に基づく燃料噴射量の分割を行う
直噴内燃機関の燃料噴射制御装置。 The fuel injection control device for a direct injection internal combustion engine according to claim 1,
A fuel injection control device for a direct injection internal combustion engine, wherein the fuel injection control means divides the fuel injection amount based on the injection amount ratio when the fuel injection amount is increased when the engine is started. 請求項２記載の直噴内燃機関の燃料噴射制御装置において、
前記燃料噴射制御手段は前記圧縮行程の燃料噴射量が前記吸気行程の燃料噴射量よりも少なくなるように前記噴射量比率を設定する
直噴内燃機関の燃料噴射制御装置。 The fuel injection control device for a direct injection internal combustion engine according to claim 2,
A fuel injection control device for a direct injection internal combustion engine, wherein the fuel injection control means sets the injection amount ratio so that a fuel injection amount in the compression stroke is smaller than a fuel injection amount in the intake stroke. 請求項３記載の直噴内燃機関の燃料噴射制御装置において、
前記燃料噴射制御手段は前記可変設定される圧縮行程の燃料噴射量について下限値を設定し、同圧縮行程の燃料噴射量が前記下限値を下回るときにこれらを等しく設定するとともにそれらの差分を前記可変設定される吸気行程の燃料噴射量から減量する
直噴内燃機関の燃料噴射制御装置。 The fuel injection control device for a direct injection internal combustion engine according to claim 3,
The fuel injection control means sets a lower limit value for the fuel injection amount of the compression stroke that is variably set, sets the same when the fuel injection amount of the compression stroke is lower than the lower limit value, and sets the difference between them. A fuel injection control device for a direct injection internal combustion engine that reduces the fuel injection amount in a variable intake stroke. 請求項４記載の直噴内燃機関の燃料噴射制御装置において、
前記燃料噴射制御手段は機関回転速度を監視し、同監視される機関回転速度が所定値以上に上昇したことを条件に前記噴射量比率による分割噴射を停止して吸気行程のみの燃料噴射を許可する
直噴内燃機関の燃料噴射制御装置。 The fuel injection control device for a direct injection internal combustion engine according to claim 4,
The fuel injection control means monitors the engine rotational speed, and on the condition that the monitored engine rotational speed has increased to a predetermined value or more, stops the divided injection based on the injection amount ratio and permits fuel injection only in the intake stroke. A fuel injection control device for a direct injection internal combustion engine. 請求項４記載の直噴内燃機関の燃料噴射制御装置において、
前記燃料噴射制御手段は燃料噴射量が所定量未満であることを条件に前記噴射量比率による分割噴射を停止して吸気行程のみの燃料噴射を許可する
直噴内燃機関の燃料噴射制御装置。 The fuel injection control device for a direct injection internal combustion engine according to claim 4,
A fuel injection control device for a direct injection internal combustion engine, wherein the fuel injection control means stops split injection based on the injection amount ratio and permits fuel injection only in an intake stroke on condition that the fuel injection amount is less than a predetermined amount.
JP2003411024A 2003-12-09 2003-12-09 Fuel injection control device for internal combustion engine Expired - Fee Related JP4329520B2 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110307099A (en) * 2018-03-27 2019-10-08 丰田自动车株式会社 The control device and control method of internal combustion engine
JP2019196765A (en) * 2018-05-11 2019-11-14 トヨタ自動車株式会社 Internal combustion engine fuel injection control apparatus

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110307099A (en) * 2018-03-27 2019-10-08 丰田自动车株式会社 The control device and control method of internal combustion engine
JP2019196765A (en) * 2018-05-11 2019-11-14 トヨタ自動車株式会社 Internal combustion engine fuel injection control apparatus

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