JP2018155217A - Controller and control method for internal combustion engine - Google Patents
Controller and control method for internal combustion engine Download PDFInfo
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本発明は、内燃機関の制御装置及び制御方法に関し、詳しくは、内燃機関の空燃比を高負荷域でリッチ化させる技術に関する。 The present invention relates to a control device and control method for an internal combustion engine, and more particularly to a technique for enriching an air-fuel ratio of an internal combustion engine in a high load region.
特許文献１に係る燃料増量制御装置は、内燃機関が高負荷域であるときに噴射燃料を増量して空燃比をリッチ化することで排気系の温度を低下させる燃料噴射制御手段を備え、前記燃料噴射制御手段は、内燃機関が高負荷域になってから内燃機関の冷却水温度に対応した時間だけ、空燃比のリッチ化を遅延させる。 The fuel increase control device according to Patent Document 1 includes fuel injection control means for reducing the temperature of the exhaust system by increasing the injected fuel and enriching the air-fuel ratio when the internal combustion engine is in a high load range, The fuel injection control means delays enrichment of the air-fuel ratio by a time corresponding to the cooling water temperature of the internal combustion engine after the internal combustion engine becomes a high load region.
ところで、内燃機関への燃料噴射を制御する制御装置が、内燃機関の高負荷域で空燃比をリッチ化させる処理の開始を冷却水温度に応じて遅延させても、遅延時間が経過したときに空燃比を理論空燃比から高負荷用のリッチ空燃比にまでシフトさせると、排気温度が低い冷機時には空燃比が過剰にリッチ化され、粒子状物質の排出量などの排気性状が悪化する場合があった。 By the way, even when the control device that controls the fuel injection to the internal combustion engine delays the start of the process of enriching the air-fuel ratio in the high load region of the internal combustion engine according to the coolant temperature, the delay time has elapsed. If the air-fuel ratio is shifted from the stoichiometric air-fuel ratio to the rich air-fuel ratio for high loads, the air-fuel ratio becomes excessively rich when the exhaust temperature is low, and the exhaust properties such as particulate matter emissions may deteriorate. there were.
本発明は上記問題点に鑑みなされたものであり、高負荷域でのリッチ化処理によって、冷機状態で排気性状が悪化することを抑えることを目的とする。 The present invention has been made in view of the above problems, and an object of the present invention is to suppress deterioration of exhaust properties in a cold state by a enrichment process in a high load region.
本発明によれば、その１つの態様において、内燃機関の高負荷域で遅延時間が経過して空燃比をリッチ方向に変化させる処理を開始するときに、空燃比のリッチ方向への変化応答を、内燃機関の運転温度が低いほどより遅くする。 According to the present invention, in one aspect thereof, when the process of changing the air-fuel ratio in the rich direction is started after the delay time has elapsed in the high load region of the internal combustion engine, the change response in the rich direction of the air-fuel ratio is The lower the operating temperature of the internal combustion engine, the slower.
上記発明によると、高負荷域でのリッチ化処理によって、冷機状態で排気性状が悪化することを抑えることができる。 According to the said invention, it can suppress that exhaust_gas | exhaustion property deteriorates in a cold machine state by the enrichment process in a high load region.
以下に本発明の実施の形態を説明する。
図１は、本発明に係る制御装置及び制御方法を適用する内燃機関の一態様を示す図である。
図１に示す内燃機関１は、車両用の火花点火ガソリン機関であり、機関本体１ａに点火装置４、燃料噴射弁５などを備える。
Embodiments of the present invention will be described below.
FIG. 1 is a diagram showing an aspect of an internal combustion engine to which a control device and a control method according to the present invention are applied.
An internal combustion engine 1 shown in FIG. 1 is a spark ignition gasoline engine for vehicles, and includes an ignition device 4, a fuel injection valve 5, and the like in an engine body 1a.
エアークリーナ７を介して吸入される空気は、電制スロットル８のスロットルバルブ８ａで流量を調節された後、燃料噴射弁５から吸気通路２ａ内に噴射される燃料と混合して燃焼室１０に吸引される。
なお、図１に示す内燃機関１は、燃料噴射弁５が吸気通路２ａ内に燃料を噴射する所謂ポート噴射式機関であるが、燃料噴射弁５が燃焼室１０内に直接燃料を噴射する筒内直接噴射式機関とすることができる。
The air sucked through the air cleaner 7 is adjusted in flow rate by the throttle valve 8 a of the electric throttle 8, and then mixed with the fuel injected from the fuel injection valve 5 into the intake passage 2 a to enter the combustion chamber 10. Sucked.
The internal combustion engine 1 shown in FIG. 1 is a so-called port injection engine in which the fuel injection valve 5 injects fuel into the intake passage 2a. However, the cylinder in which the fuel injection valve 5 directly injects fuel into the combustion chamber 10 is used. It can be an internal direct injection engine.
電制スロットル８は、スロットルモータ８ｂでスロットルバルブ８ａを開閉する装置であり、スロットルバルブ８ａの開度ＴＰＳに対応する信号を出力するスロットル開度センサ８ｃを備える。
回転数検出装置６は、リングギア１４の突起を検出することで、クランクシャフト１７の所定回転角毎の回転角信号ＮＥを出力する。
The electric throttle 8 is a device that opens and closes the throttle valve 8a with a throttle motor 8b, and includes a throttle opening sensor 8c that outputs a signal corresponding to the opening TPS of the throttle valve 8a.
The rotation speed detection device 6 outputs a rotation angle signal NE for each predetermined rotation angle of the crankshaft 17 by detecting the protrusion of the ring gear 14.
水温センサ１５は、機関本体１ａに設けられたウォータジャケット１８内の冷却水の温度（以下、水温ＴＷと称する）に対応する信号を出力する。
流量検出装置９は、電制スロットル８の上流側に配置され、内燃機関１の吸入空気流量ＱＡＲに対応する信号を出力する。
The water temperature sensor 15 outputs a signal corresponding to the temperature of the cooling water in the water jacket 18 provided in the engine body 1a (hereinafter referred to as the water temperature TW).
The flow rate detection device 9 is disposed upstream of the electric control throttle 8 and outputs a signal corresponding to the intake air flow rate QAR of the internal combustion engine 1.
また、排気通路（排気管）３ａに配置される排気浄化触媒装置１２は、内燃機関１の排気を浄化する。
空燃比センサ１１は、排気浄化触媒装置１２の上流側の排気通路３ａに配置され、排気空燃比ＲＡＢＦ（酸素濃度）に対応する信号を出力する。
Further, the exhaust purification catalyst device 12 disposed in the exhaust passage (exhaust pipe) 3 a purifies the exhaust gas of the internal combustion engine 1.
The air-fuel ratio sensor 11 is disposed in the exhaust passage 3a on the upstream side of the exhaust purification catalyst device 12, and outputs a signal corresponding to the exhaust air-fuel ratio RABF (oxygen concentration).
また、排気温度センサ１６は、排気浄化触媒装置１２の上流側の排気通路３ａに配置され、排気浄化触媒装置１２の入口での排気温度ＴＥＸ（℃）に対応する信号を出力する。
燃料噴射弁５には、図示省略した燃料供給装置によって燃料タンク内の燃料が所定圧力に調整されて供給される。
The exhaust temperature sensor 16 is disposed in the exhaust passage 3 a on the upstream side of the exhaust purification catalyst device 12 and outputs a signal corresponding to the exhaust temperature TEX (° C.) at the inlet of the exhaust purification catalyst device 12.
The fuel in the fuel tank is adjusted to a predetermined pressure and supplied to the fuel injection valve 5 by a fuel supply device (not shown).
マイクロコンピュータを内蔵する制御装置１３は、前述した各種センサから出力される、開度ＴＰＳの信号、吸入空気流量ＱＡＲの信号、回転角信号ＮＥ、水温ＴＷの信号、排気空燃比ＲＡＢＦの信号、排気温度ＴＥＸの信号などを取り込む。
そして、制御装置１３は、取り込んだ信号に基づき燃料噴射量（燃料噴射パルス幅）ＴＩを演算し、燃料噴射量ＴＩに基づき燃料噴射弁５を制御する。
更に、制御装置１３は、点火装置４、電制スロットル８にも操作量を出力し、点火装置４の点火時期やスロットルバルブ８ａの開度を制御して、内燃機関１の運転を制御する。
The control device 13 incorporating the microcomputer outputs the signal of the opening degree TPS, the signal of the intake air flow rate QAR, the signal of the rotation angle signal NE, the signal of the water temperature TW, the signal of the exhaust air-fuel ratio RABF, the exhaust gas output from the various sensors described above. Captures temperature TEX signal.
Then, the control device 13 calculates a fuel injection amount (fuel injection pulse width) TI based on the acquired signal, and controls the fuel injection valve 5 based on the fuel injection amount TI.
Further, the control device 13 outputs the operation amount to the ignition device 4 and the electric throttle 8, and controls the ignition timing of the ignition device 4 and the opening degree of the throttle valve 8 a to control the operation of the internal combustion engine 1.
制御装置１３は、データ（各種センサの計測結果や各種装置に出力する操作量）の入出力を行うために、アナログ入力回路２０、Ａ／Ｄ変換回路２１、デジタル入力回路２２、出力回路２３及びＩ／Ｏ回路２４を備える。
また、制御装置１３は、データの演算処理を行うために、ＭＰＵ２６、ＲＯＭ２７、ＲＡＭ２８を含むマイクロコンピュータを備える。
The control device 13 inputs / outputs data (measurement results of various sensors and operation amounts output to various devices), an analog input circuit 20, an A / D conversion circuit 21, a digital input circuit 22, an output circuit 23, and An I / O circuit 24 is provided.
In addition, the control device 13 includes a microcomputer including an MPU 26, a ROM 27, and a RAM 28 in order to perform data calculation processing.
アナログ入力回路２０には、吸入空気流量ＱＡＲの信号、開度ＴＰＳの信号、排気空燃比ＲＡＢＦの信号、排気温度ＴＥＸの信号、及び、水温ＴＷの信号などが入力される。
アナログ入力回路２０に入力された各種信号は、それぞれＡ／Ｄ変換回路２１に供給されてデジタル信号に変換され、バス２５上に出力される。
The analog input circuit 20 is supplied with an intake air flow rate QAR signal, an opening degree TPS signal, an exhaust air / fuel ratio RABF signal, an exhaust temperature TEX signal, a water temperature TW signal, and the like.
Various signals input to the analog input circuit 20 are respectively supplied to the A / D conversion circuit 21, converted into digital signals, and output onto the bus 25.
また、デジタル入力回路２２に入力された回転角信号ＮＥは、Ｉ／Ｏ回路２４を介してバス２５上に出力される。
バス２５には、ＭＰＵ（Microprocessor Unit）２６、ＲＯＭ（Read Only Memory）２７、ＲＡＭ（Random Access Memory）２８、タイマ／カウンタ（ＴＭＲ／ＣＮＴ）２９等が接続されている。そして、ＭＰＵ２６、ＲＯＭ２７、ＲＡＭ２８は、バス２５を介してデータの授受を行う。
The rotation angle signal NE input to the digital input circuit 22 is output on the bus 25 via the I / O circuit 24.
An MPU (Microprocessor Unit) 26, a ROM (Read Only Memory) 27, a RAM (Random Access Memory) 28, a timer / counter (TMR / CNT) 29, and the like are connected to the bus 25. The MPU 26, ROM 27, and RAM 28 exchange data via the bus 25.
ＭＰＵ２６には、クロックジェネレータ３０からクロック信号が供給され、ＭＰＵ２６は、クロック信号に同期して様々な演算や処理を実行する。
ＲＯＭ２７は、例えばデータの消去と書き換えが可能なＥＥＰＲＯＭ（Electrically Erasable Programmable Read-Only Memory）で構成され、制御装置１３を動作させるためのプログラム、設定データ及び初期値などを記憶する。
A clock signal is supplied from the clock generator 30 to the MPU 26, and the MPU 26 executes various calculations and processes in synchronization with the clock signal.
The ROM 27 is composed of, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory) capable of erasing and rewriting data, and stores a program for operating the control device 13, setting data, initial values, and the like.
ＲＯＭ２７が記憶する情報は、バス２５を介してＲＡＭ２８及びＭＰＵ２６に読み込まれる。
ＲＡＭ２８は、ＭＰＵ２６による演算結果や処理結果を一時的に記憶する作業領域として用いられる。
Information stored in the ROM 27 is read into the RAM 28 and the MPU 26 via the bus 25.
The RAM 28 is used as a work area for temporarily storing calculation results and processing results by the MPU 26.
なお、タイマ／カウンタ２９は、時間の測定や様々な回数の測定などに用いられる。
ＭＰＵ２６による演算結果や処理結果は、バス２５上に出力された後、Ｉ／Ｏ回路２４を介して出力回路２３から点火装置４、燃料噴射弁５、電制スロットル８などに供給される。
The timer / counter 29 is used for measuring time, measuring various times, and the like.
Calculation results and processing results by the MPU 26 are output on the bus 25 and then supplied from the output circuit 23 to the ignition device 4, the fuel injection valve 5, the electric throttle 8, and the like via the I / O circuit 24.
制御装置１３は、燃料噴射弁５の燃料噴射量の制御において、高負荷領域での空燃比を低中負荷域での空燃比（理論空燃比＝14.7）よりもリッチ化させる燃料増量処理を実施する機能（空燃比制御部）をソフトウェアとして備える。
上記の燃料増量処理は、高負荷域で排気温度が上昇して排気浄化触媒装置１２などの排気系部品が熱劣化することを抑制するための処理である。
In the control of the fuel injection amount of the fuel injection valve 5, the control device 13 performs a fuel increase process that makes the air-fuel ratio in the high load region richer than the air-fuel ratio in the low-medium load region (theoretical air-fuel ratio = 14.7). Function (air-fuel ratio control unit) is provided as software.
The fuel increase process described above is a process for suppressing the exhaust system temperature such as the exhaust purification catalyst device 12 from being thermally deteriorated due to the exhaust temperature rising in a high load range.
制御装置１３は、例えば、理論空燃比の混合気が形成される基本燃料噴射量ＴＰを演算し、この基本燃料噴射量ＴＰに増量係数ＫＭＲ（ＫＭＲ≧1.0）を乗算した結果を最終的な燃料噴射量ＴＩに設定するよう構成される。
そして、制御装置１３は、高負荷域で増量係数ＫＭＲを1.0よりも大きな値に設定することで、燃料噴射量ＴＩを基本燃料噴射量ＴＰよりも増量させて、空燃比を理論空燃比よりもリッチに制御する。
For example, the control device 13 calculates a basic fuel injection amount TP in which a stoichiometric air-fuel mixture is formed, and multiplies the basic fuel injection amount TP by an increase coefficient KMR (KMR ≧ 1.0) as a final fuel. It is configured to set the injection amount TI.
Then, the control device 13 sets the increase coefficient KMR to a value larger than 1.0 in the high load region, thereby increasing the fuel injection amount TI from the basic fuel injection amount TP, so that the air-fuel ratio becomes higher than the stoichiometric air-fuel ratio. Rich control.
制御装置１３による燃料噴射制御によって空燃比がリッチ化すると、燃焼速度が高くなって後燃えが緩和され、また、未燃焼ガソリンの気化潜熱によってシリンダ壁などが冷却されることで、排気温度の上昇が抑制される。
つまり、空燃比を理論空燃比よりもリッチ化させる高負荷域とは、理論空燃比の混合気を燃焼させることで、排気系部品の熱劣化を発生させ得るほどに排気温度が上昇する負荷域である。換言すれば、空燃比を理論空燃比よりもリッチ化させる高負荷域とは、空燃比を理論空燃比としたときに排気温度が排気系部品の保護のための上限温度を超えることがある負荷域である。
When the air-fuel ratio is enriched by the fuel injection control by the control device 13, the combustion speed is increased, the afterburning is mitigated, and the cylinder wall is cooled by the latent heat of vaporization of the unburned gasoline, thereby increasing the exhaust temperature. Is suppressed.
In other words, the high load range in which the air-fuel ratio is made richer than the stoichiometric air-fuel ratio is a load range in which the exhaust temperature rises to such an extent that thermal deterioration of the exhaust system parts can occur by burning the air-fuel mixture with the stoichiometric air-fuel ratio It is. In other words, the high load range in which the air-fuel ratio is made richer than the stoichiometric air-fuel ratio is a load in which the exhaust temperature may exceed the upper limit temperature for protecting exhaust system components when the air-fuel ratio is set to the stoichiometric air-fuel ratio. It is an area.
以下では、制御装置１３による燃料増量処理（高負荷域での空燃比リッチ化処理）を詳細に説明する。
図２は、制御装置１３による燃料増量処理の流れ（空燃比制御部としての演算機能）を示すフローチャートである。
制御装置１３は、図２のフローチャートに示す処理を、一定時間毎の割り込み処理で実施する。
Hereinafter, fuel increase processing (air-fuel ratio enrichment processing in a high load range) by the control device 13 will be described in detail.
FIG. 2 is a flowchart showing the flow of fuel increase processing by the control device 13 (calculation function as an air-fuel ratio control unit).
The control device 13 performs the process shown in the flowchart of FIG. 2 as an interrupt process at regular intervals.
制御装置１３は、まず、ステップＳ１０１で、内燃機関１の負荷が燃料増量処理（空燃比のリッチ化処理）を実施する所定の高負荷域になっているか否かを判断する。
制御装置１３は、例えば、スロットルバルブ８ａの開度ＴＰＳと閾値ＴＨＴＰとを比較し、開度ＴＰＳが閾値ＴＨＴＰを上回るときに、内燃機関１の負荷が燃料増量処理の実施領域（空燃比リッチ化域）になっていると判断することができる。
First, in step S101, the control device 13 determines whether or not the load of the internal combustion engine 1 is in a predetermined high load region in which fuel increase processing (air-fuel ratio enrichment processing) is performed.
For example, the control device 13 compares the opening degree TPS of the throttle valve 8a with a threshold value THTP, and when the opening degree TPS exceeds the threshold value THTP, the load of the internal combustion engine 1 is subjected to the fuel increase process execution region (air-fuel ratio enrichment). It can be determined that
また、制御装置１３は、スロットルバルブ８ａの開度ＴＰＳに代えて、吸入空気量、吸気負圧、基本燃料噴射量などに基づき、内燃機関１の負荷が燃料増量処理の実施領域になっているか否かを判断することができる。
内燃機関１の負荷が燃料増量処理を実施する所定の高負荷域になっていない場合、つまり、内燃機関１の負荷が、排気温度の上昇抑制のための燃料増量補正（空燃比リッチ化）が不要な低中負荷域である場合、制御装置１３は、ステップＳ１０１からステップＳ１１５に進む。
In addition, the control device 13 determines whether the load of the internal combustion engine 1 is in the execution region of the fuel increase process based on the intake air amount, the intake negative pressure, the basic fuel injection amount, etc., instead of the opening degree TPS of the throttle valve 8a. It can be determined whether or not.
When the load of the internal combustion engine 1 is not in a predetermined high load region where the fuel increase process is performed, that is, the load of the internal combustion engine 1 is corrected for fuel increase (air-fuel ratio enrichment) for suppressing an increase in exhaust temperature. In the case of an unnecessary low / medium load range, the control device 13 proceeds from step S101 to step S115.
制御装置１３は、ステップＳ１１５で、高負荷域での燃料増量処理の開始を遅らせる時間を計測するための遅延用カウンタＣＮＴ１をリセットする。
次いで、制御装置１３は、ステップＳ１１６に進んで、燃料増量補正（空燃比のリッチ化処理）を実施することなく、燃料噴射弁５による燃料噴射を行わせる。つまり、制御装置１３は、ステップＳ１１６で、増量係数ＫＭＲを1.0に設定して理論空燃比の混合気を形成させる燃料噴射量ＴＩを演算し、当該燃料噴射量ＴＩに基づき燃料噴射弁５による燃料噴射を制御することで、内燃機関１の空燃比を理論空燃比に制御する。
In step S115, the control device 13 resets the delay counter CNT1 for measuring the time for delaying the start of the fuel increase process in the high load region.
Next, the control device 13 proceeds to step S116 to cause the fuel injection valve 5 to perform fuel injection without performing fuel increase correction (air-fuel ratio enrichment processing). That is, in step S116, the control device 13 sets the increase coefficient KMR to 1.0, calculates the fuel injection amount TI that forms the stoichiometric air-fuel mixture, and based on the fuel injection amount TI, the fuel by the fuel injection valve 5 is calculated. By controlling the injection, the air-fuel ratio of the internal combustion engine 1 is controlled to the stoichiometric air-fuel ratio.
但し、内燃機関１の負荷が低中負荷域であるときの空燃比は理論空燃比に限定されない。つまり、低中負荷域で空燃比を理論空燃比とし高負荷域で空燃比を理論空燃比よりもリッチにする処理は、高負荷域での空燃比を低中負荷域での空燃比よりもリッチに制御する処理の一態様である。 However, the air-fuel ratio when the load of the internal combustion engine 1 is in the low-medium load region is not limited to the stoichiometric air-fuel ratio. In other words, the process of making the air-fuel ratio the stoichiometric air-fuel ratio in the low-medium load range and making the air-fuel ratio richer than the stoichiometric air-fuel ratio in the high-load range is less than the air-fuel ratio in the low-medium load range. It is one mode of processing to perform rich control.
一方、内燃機関１の負荷が燃料増量処理を実施する所定の高負荷域になっている場合、制御装置１３は、ステップＳ１０１からステップＳ１０２に進む。
制御装置１３は、ステップＳ１０２で、遅延用カウンタＣＮＴ１による遅延時間の計測中であるか否かを判断する。
On the other hand, when the load of the internal combustion engine 1 is in a predetermined high load region where the fuel increase processing is performed, the control device 13 proceeds from step S101 to step S102.
In step S102, the control device 13 determines whether or not the delay time is being measured by the delay counter CNT1.
そして、制御装置１３は、遅延用カウンタＣＮＴ１による遅延時間の計測中でない場合、ステップＳ１０３に進んで、遅延用カウンタＣＮＴ１について初期値からのインクリメントを開始させた後、ステップＳ１０４に進む。
内燃機関１の負荷が燃料増量処理を実施する所定の高負荷域になっていない間において、制御装置１３は、ステップＳ１１５で遅延用カウンタＣＮＴ１をリセットし、内燃機関１の負荷が燃料増量処理を実施する所定の高負荷域になったときから遅延用カウンタＣＮＴ１による時間計測を行わせる。
If the delay time is not being measured by the delay counter CNT1, the control device 13 proceeds to step S103, starts incrementing the delay counter CNT1 from the initial value, and then proceeds to step S104.
While the load of the internal combustion engine 1 is not in the predetermined high load range for performing the fuel increase process, the control device 13 resets the delay counter CNT1 in step S115, and the load of the internal combustion engine 1 performs the fuel increase process. The time is measured by the delay counter CNT1 from the time when the predetermined high load range is reached.
また、制御装置１３は、遅延用カウンタＣＮＴ１による時間計測中である場合、ステップＳ１０３を迂回してステップＳ１０４に進むことで、遅延用カウンタＣＮＴ１のインクリメントを継続させる。
制御装置１３は、ステップＳ１０４で、水温ＴＷを読み込み、次のステップＳ１０５（遅延時間設定部）で、高負荷域になってから燃料増量処理を開始させるまでの遅延時間ＤＴを水温ＴＷに基づき設定する。
なお、水温ＴＷは、内燃機関１の運転温度を代表する温度である。
Further, when the time is being measured by the delay counter CNT1, the control device 13 bypasses step S103 and proceeds to step S104 to continue incrementing the delay counter CNT1.
In step S104, the control device 13 reads the water temperature TW, and in the next step S105 (delay time setting unit), sets a delay time DT until the fuel increase processing is started after the high load range is reached based on the water temperature TW. To do.
The water temperature TW is a temperature representative of the operating temperature of the internal combustion engine 1.
図３は、水温ＴＷと遅延時間ＤＴとの相関の一態様を示す線図であり、水温ＴＷに対応する遅延時間ＤＴを記憶する変換テーブルを例示する。
制御装置１３は、図３に示した変換テーブルを記憶し、当該変換テーブルを参照して、そのときの水温ＴＷに対応する遅延時間ＤＴを求めることができる。
FIG. 3 is a diagram illustrating one aspect of the correlation between the water temperature TW and the delay time DT, and illustrates a conversion table that stores the delay time DT corresponding to the water temperature TW.
The control device 13 can store the conversion table shown in FIG. 3 and refer to the conversion table to obtain the delay time DT corresponding to the water temperature TW at that time.
ここで、制御装置１３は、水温ＴＷが低いほどより長い遅延時間ＤＴを設定する。
つまり、制御装置１３は、所定の高負荷域になっても直ちに燃料増量（空燃比のリッチ化）を実施せず、水温ＴＷ（内燃機関１の運転温度）が低いほど燃料増量（空燃比のリッチ化）の開始をより遅らせることで、排気温度ＴＥＸの上昇による排気系部品の熱劣化を抑制しつつ、過剰なリッチ化による排気性状の悪化（粒子状物質の排出量）を抑える。
Here, the control device 13 sets a longer delay time DT as the water temperature TW is lower.
That is, the control device 13 does not immediately perform fuel increase (air-fuel ratio enrichment) even when a predetermined high load range is reached, and the fuel increase (air-fuel ratio increase) as the water temperature TW (operating temperature of the internal combustion engine 1) decreases. By further delaying the start of enrichment, deterioration of exhaust properties (exhaust amount of particulate matter) due to excessive enrichment is suppressed while suppressing thermal deterioration of exhaust system parts due to an increase in exhaust temperature TEX.
なお、図３に示した変換テーブルは、水温ＴＷの上昇に比例して遅延時間ＤＴが一定速度で短縮方向に変化する特性を示すが、係る変化特性に限定されるものではなく、制御装置１３における水温ＴＷと遅延時間ＤＴとの相関は、排気温度ＴＥＸの上昇特性などに応じて適宜変更され得る。 The conversion table shown in FIG. 3 shows a characteristic in which the delay time DT changes in the shortening direction at a constant speed in proportion to the increase in the water temperature TW. However, the conversion table is not limited to such a change characteristic. The correlation between the water temperature TW and the delay time DT can be appropriately changed according to the rise characteristic of the exhaust temperature TEX.
制御装置１３は、ステップＳ１０５で遅延時間ＤＴを設定すると、次いで、ステップＳ１０６（遅延処理部）に進み、遅延用カウンタＣＮＴ１によって計測される高負荷域になってからの経過時間が水温ＴＷに応じた遅延時間ＤＴ以上になっているか否かを判別する。 After setting the delay time DT in step S105, the control device 13 proceeds to step S106 (delay processing unit), and the elapsed time after becoming the high load range measured by the delay counter CNT1 corresponds to the water temperature TW. It is determined whether the delay time DT is equal to or longer than the delay time DT.
高負荷域になってからの経過時間が水温ＴＷに応じた遅延時間ＤＴに達していない場合、つまり、高負荷域になってから燃料増量（空燃比のリッチ化）を開始させるまでの遅延時間ＤＴ内である場合、制御装置１３は、ステップＳ１１６に進む。
ステップＳ１１６で、制御装置１３は、増量係数ＫＭＲを1.0に設定して内燃機関１の空燃比を理論空燃比に制御することで、高負荷域であっても増量補正（空燃比のリッチ化処理）の実施をキャンセルし、低中負荷域と同じ空燃比（理論空燃比）に維持させる。
When the elapsed time since the high load range has not reached the delay time DT corresponding to the water temperature TW, that is, the delay time from when the high load range is reached until the fuel increase (air-fuel ratio enrichment) starts. If it is within the DT, the control device 13 proceeds to step S116.
In step S116, the control device 13 sets the increase coefficient KMR to 1.0 and controls the air-fuel ratio of the internal combustion engine 1 to the stoichiometric air-fuel ratio, so that the increase correction (air-fuel ratio enrichment processing) is performed even in the high load range. ) Is canceled and maintained at the same air-fuel ratio (theoretical air-fuel ratio) as the low-medium load range.
一方、高負荷域になってからの経過時間が水温ＴＷに応じた遅延時間ＤＴ以上になると、つまり、高負荷域での増量補正を開始するタイミングになると、制御装置１３は、燃料増量補正（空燃比のリッチ化処理）を実施するためにステップＳ１０６からステップＳ１０７に進む。 On the other hand, when the elapsed time after becoming the high load region becomes equal to or longer than the delay time DT corresponding to the water temperature TW, that is, when it is time to start increasing correction in the high load region, the controller 13 corrects the fuel increase correction ( In order to carry out the air-fuel ratio enrichment process, the process proceeds from step S106 to step S107.
図４は、制御装置１３による燃料増量補正を概説するためのタイムチャートであり、機関負荷の変化に対する空燃比、排気温度ＴＥＸ、粒子状物質の排出量の変化を例示する。
図４に示すように、制御装置１３は、高負荷域（燃料増量域）になった時刻ｔ１から遅延時間ＤＴが経過し、時刻ｔ２にて燃料増量処理を開始させるときに、まず、増量係数ＫＭＲを1.0からＫＭＲ１（ＫＭＲ１＞1.0）にシフトさせることで、空燃比をリッチ方向にシフトさせ、空燃比を理論空燃比よりも弱リッチに設定する。
FIG. 4 is a time chart for explaining the fuel increase correction by the control device 13, and illustrates the change of the air-fuel ratio, the exhaust temperature TEX, and the discharge amount of the particulate matter with respect to the change of the engine load.
As shown in FIG. 4, when the delay time DT elapses from time t1 when the control device 13 enters the high load range (fuel increase range) and the fuel increase processing is started at time t2, first, the control unit 13 increases the increase coefficient. By shifting KMR from 1.0 to KMR1 (KMR1> 1.0), the air-fuel ratio is shifted in the rich direction, and the air-fuel ratio is set to be slightly richer than the stoichiometric air-fuel ratio.
そして、制御装置１３は、増量係数ＫＭＲ１による増量状態（弱リッチ化状態）を時刻ｔ２から保持時間ＲＥＴだけ保持させ、保持時間ＲＥＴが経過した時刻ｔ３で、増量係数ＫＭＲを高負荷域での増量補正の最終的な目標値であるＫＭＲ２（ＫＭＲ２＞ＫＭＲ１＞1.0）にまでシフトさせることで、空燃比を更にリッチ方向にシフトさせる。
ここで、増量係数ＫＭＲをＫＭＲ１としたときの空燃比ＡＦ１（応答調整用の弱リッチ空燃比）は例えば13.0以上であり、増量係数ＫＭＲをＫＭＲ２としたときの空燃比ＡＦ２（高負荷用のリッチ空燃比）は例えば12.0程度である（14.7＞ＡＦ１≧13.0＞ＡＦ２）。
Then, the control device 13 holds the increase state (weakly enriched state) by the increase coefficient KMR1 for the holding time RET from the time t2, and increases the increase coefficient KMR in the high load region at the time t3 when the holding time RET has elapsed. By shifting to KMR2 (KMR2>KMR1> 1.0) which is the final target value for correction, the air-fuel ratio is further shifted in the rich direction.
Here, the air-fuel ratio AF1 (weak rich air-fuel ratio for response adjustment) when the increase coefficient KMR is set to KMR1 is, for example, 13.0 or more, and the air-fuel ratio AF2 (rich for high load) when the increase coefficient KMR is set to KMR2 The air / fuel ratio is, for example, about 12.0 (14.7> AF1 ≧ 13.0> AF2).
そして、内燃機関１が高負荷域になると、制御装置１３による噴射量制御によって、空燃比は、理論空燃比＝14.7、空燃比ＡＦ１、空燃比ＡＦ２の順にリッチ方向に向かって段階的に切り替わることになる。
制御装置１３は、図２のフローチャートのステップＳ１０７で、水温ＴＷを読み込み、次のステップＳ１０８では、高負荷域での燃料増量処理において、最初の段階の増量レベル（リッチ空燃比）を決定する増量係数ＫＭＲ１を水温ＴＷに基づき設定する。
When the internal combustion engine 1 is in a high load range, the air-fuel ratio is switched stepwise toward the rich direction in the order of the theoretical air-fuel ratio = 14.7, the air-fuel ratio AF1, and the air-fuel ratio AF2 by the injection amount control by the control device 13. become.
The control device 13 reads the water temperature TW in step S107 of the flowchart of FIG. 2, and in the next step S108, in the fuel increase process in the high load region, the increase amount for determining the increase level (rich air-fuel ratio) at the first stage. The coefficient KMR1 is set based on the water temperature TW.
図５は、水温ＴＷと増量係数ＫＭＲ１との相関を例示する線図である。制御装置１３は、増量係数ＫＭＲ１（ＫＭＲ１＞1.0）を水温ＴＷが低いほどより小さく設定することで、増量係数ＫＭＲ１による増量状態での空燃比ＡＦ１を水温ＴＷが低いほどより理論空燃比に近づけ、冷機状態でリッチ化を小さく抑える。
更に、制御装置１３は、次のステップＳ１０９で、増量係数ＫＭＲ１による増量状態（空燃比ＡＦ１）を保持させる保持時間ＲＥＴを、水温ＴＷに基づき設定する。
FIG. 5 is a diagram illustrating the correlation between the water temperature TW and the increase coefficient KMR1. The control device 13 sets the increase coefficient KMR1 (KMR1> 1.0) to be smaller as the water temperature TW is lower, so that the air-fuel ratio AF1 in the increased state by the increase coefficient KMR1 is closer to the theoretical air-fuel ratio as the water temperature TW is lower. Minimize enrichment in cold conditions.
Further, in the next step S109, the control device 13 sets a holding time RET for holding the increased state (air-fuel ratio AF1) by the increasing coefficient KMR1 based on the water temperature TW.
図６は、水温ＴＷと保持時間ＲＥＴとの相関を例示する線図であり、制御装置１３は、保持時間ＲＥＴを水温ＴＷが低いほどより長く設定する。
制御装置１３は、増量係数ＫＭＲ１（ＫＭＲ１＞1.0）を水温ＴＷが低いほどより小さく設定し（換言すれば、空燃比ＡＦ１（14.7＞ＡＦ１）を水温ＴＷが低いほどより大きく設定し）、また、保持時間ＲＥＴを水温ＴＷが低いほどより長く設定することで、高負荷域でのリッチ化処理を開始した後の空燃比のリッチ方向への変化応答、つまり、理論空燃比から増量係数ＫＭＲ２でのリッチ空燃比ＡＦ２までの変化応答を、水温ＴＷ（内燃機関１の運転温度）が低いほどより遅くする。
FIG. 6 is a diagram illustrating the correlation between the water temperature TW and the holding time RET. The control device 13 sets the holding time RET longer as the water temperature TW is lower.
The control device 13 sets the increase coefficient KMR1 (KMR1> 1.0) smaller as the water temperature TW is lower (in other words, sets the air-fuel ratio AF1 (14.7> AF1) larger as the water temperature TW is lower), and By setting the holding time RET longer as the water temperature TW is lower, the change response in the rich direction of the air-fuel ratio after starting the enrichment process in the high load region, that is, from the stoichiometric air-fuel ratio to the increase coefficient KMR2 The change response to the rich air-fuel ratio AF2 is made slower as the water temperature TW (operating temperature of the internal combustion engine 1) is lower.
制御装置１３は、ステップＳ１０９にて保持時間ＲＥＴを水温ＴＷに基づき設定した後、ステップＳ１１０に進み、増量係数ＫＭＲ１による増量処理を保持する保持時間ＲＥＴを保持用カウンタＣＮＴ２により計測中であるか否かを判断する。
そして、保持用カウンタＣＮＴ２による保持時間ＲＥＴの計測が開始されていない場合、制御装置１３は、ステップＳ１１１に進み、保持用カウンタＣＮＴ２の初期値からのインクリメントを開始させた後、ステップＳ１１２に進む。
After setting the holding time RET based on the water temperature TW in step S109, the control device 13 proceeds to step S110 and determines whether or not the holding counter CNT2 is measuring the holding time RET for holding the increase processing by the increase coefficient KMR1. Determine whether.
If measurement of the holding time RET by the holding counter CNT2 has not been started, the control device 13 proceeds to step S111, starts incrementing from the initial value of the holding counter CNT2, and then proceeds to step S112.
一方、制御装置１３は、保持用カウンタＣＮＴ２による保持時間ＲＥＴの計測中である場合、ステップＳ１１１を迂回してステップＳ１１２に進むことで、保持用カウンタＣＮＴ２のインクリメントを継続させる。
制御装置１３は、ステップＳ１１２で保持用カウンタＣＮＴ２による計測時間が保持時間ＲＥＴ以上になっているか否かを判断する。
On the other hand, when the holding time RET is being measured by the holding counter CNT2, the control device 13 bypasses step S111 and proceeds to step S112 to continue incrementing the holding counter CNT2.
In step S112, the control device 13 determines whether the measurement time by the holding counter CNT2 is equal to or longer than the holding time RET.
保持用カウンタＣＮＴ２による計測時間が保持時間ＲＥＴ未満である場合、制御装置１３は、ステップＳ１１２からステップＳ１１３に進んで増量係数ＫＭＲ１による燃料噴射量の燃料増量処理を実施し、空燃比を理論空燃比よりも弱リッチの空燃比ＡＦ１に制御する。
これにより、内燃機関１の空燃比は、高負荷域になってからの時間が遅延時間ＤＴに達したときに理論空燃比からリッチ方向にシフトし、シフト後の弱リッチの空燃比ＡＦ１を保持時間ＲＥＴだけ維持することになる。
When the measurement time by the holding counter CNT2 is less than the holding time RET, the control device 13 proceeds from step S112 to step S113, performs fuel increase processing of the fuel injection amount by the increase coefficient KMR1, and sets the air-fuel ratio to the theoretical air-fuel ratio. The air-fuel ratio AF1 is controlled to be slightly richer.
As a result, the air-fuel ratio of the internal combustion engine 1 shifts from the stoichiometric air-fuel ratio in the rich direction when the time after the high load region reaches the delay time DT, and maintains the weakly rich air-fuel ratio AF1 after the shift. Only the time RET is maintained.
そして、ステップＳ１１２で保持用カウンタＣＮＴ２による計測時間が保持時間ＲＥＴ以上になると、換言すれば、増量係数ＫＭＲ１による燃料増量処理の継続時間が保持時間ＲＥＴに達すると、制御装置１３は、ステップＳ１１２からステップＳ１１４に進む。
制御装置１３は、ステップＳ１１４で、増量係数ＫＭＲ２による燃料噴射量の燃料増量処理を実施することで、増量係数ＫＭＲ１（ＫＭＲ１＜ＫＭＲ２）により燃料噴射量を増量するときよりも更に燃料噴射量を増量し、空燃比を空燃比ＡＦ１よりも更にリッチ方向にシフトさせ、空燃比ＡＦ２（高負荷用のリッチ空燃比）に維持させる。
In step S112, when the measurement time by the holding counter CNT2 becomes equal to or longer than the holding time RET, in other words, when the continuation time of the fuel increase processing by the increase coefficient KMR1 reaches the holding time RET, the control device 13 starts from step S112. Proceed to step S114.
In step S114, the control device 13 increases the fuel injection amount further than when increasing the fuel injection amount by the increase coefficient KMR1 (KMR1 <KMR2) by performing the fuel increase process of the fuel injection amount by the increase coefficient KMR2. Then, the air-fuel ratio is shifted further in the rich direction than the air-fuel ratio AF1, and is maintained at the air-fuel ratio AF2 (rich air-fuel ratio for high load).
つまり、制御装置１３による高負荷域での空燃比制御は、図４に示したように、内燃機関１の負荷が高負荷域になってから遅延時間ＤＴだけ空燃比を理論空燃比に維持する第１段階と、遅延時間ＤＴが経過してから保持時間ＲＥＴだけ空燃比を理論空燃比よりもリッチで高負荷用のリッチ空燃比ＡＦ２よりもリーンである応答調整用の空燃比ＡＦ１（ＡＦ２＜ＡＦ１＜14.7）に維持する第２段階と、保持時間ＲＥＴが経過した後に空燃比を高負荷用のリッチ空燃比ＡＦ２（ＡＦ２＜ＡＦ１＜14.7）に制御する第３段階とで構成される。 That is, the air-fuel ratio control in the high load region by the control device 13 maintains the air-fuel ratio at the stoichiometric air-fuel ratio for the delay time DT after the load of the internal combustion engine 1 becomes the high load region as shown in FIG. In the first stage, the air-fuel ratio for response adjustment AF1 (AF2 <AF2 <AF2) which is richer than the theoretical air-fuel ratio and leaner than the rich air-fuel ratio AF2 for high load after the delay time DT has elapsed. The second stage is maintained at AF1 <14.7), and the third stage is used to control the air-fuel ratio to a high air-fuel ratio AF2 for high load (AF2 <AF1 <14.7) after the retention time RET has elapsed.
ここで、制御装置１３がステップＳ１０８で増量係数ＫＭＲ１（応答調整用の空燃比ＡＦ１）を水温ＴＷに基づき設定する処理と、制御装置１３がステップＳ１０９で増量係数ＫＭＲ１（応答調整用の空燃比ＡＦ１）の保持時間ＲＥＴを水温ＴＷに基づき設定する処理とが、制御装置１３における応答設定部としての機能に相当する。
そして、制御装置１３は、高負荷域でのリッチ化の応答を水温ＴＷが低いほどより遅くすることで、燃料増量処理の開始直後の空燃比を冷機時には暖機後よりも理論空燃比に近づけるから、排気温度の上昇が遅れる冷機時に過剰なリッチシフトによって排気性状（粒子状物質の排出量）が悪化することが抑制される（図４参照）。
Here, the control device 13 sets the increase coefficient KMR1 (response adjustment air-fuel ratio AF1) based on the water temperature TW in step S108, and the control device 13 increases the increase coefficient KMR1 (response adjustment air-fuel ratio AF1) in step S109. ) Of setting the holding time RET based on the water temperature TW corresponds to a function as a response setting unit in the control device 13.
Then, the control device 13 makes the response of enrichment in the high load region slower as the water temperature TW is lower, so that the air-fuel ratio immediately after the start of the fuel increasing process is closer to the stoichiometric air-fuel ratio than after warm-up when the engine is cold. Therefore, it is possible to suppress deterioration of exhaust properties (particulate matter discharge amount) due to an excessive rich shift at the time of cooling when the exhaust temperature rise is delayed (see FIG. 4).
つまり、増量係数ＫＭＲ１が、粒子状物質の排出量を十分に抑制できる空燃比となる値に設定され、また、保持時間ＲＥＴが、排気温度ＴＥＸの上昇が抑えられる時間に設定されることで、排気系部品の熱劣化を抑制できる排気温度ＴＥＸに制限しつつ粒子状物質の排出量の増加を抑制できる。
なお、制御装置１３は、増量係数ＫＭＲ１と保持時間ＲＥＴとのいずれか一方を固定値とし、他方を水温ＴＷに応じて変更することができる。
That is, the increase coefficient KMR1 is set to a value that provides an air-fuel ratio that can sufficiently suppress the discharge amount of particulate matter, and the holding time RET is set to a time during which the increase in the exhaust gas temperature TEX is suppressed. It is possible to suppress an increase in the discharge amount of the particulate matter while limiting to the exhaust temperature TEX that can suppress the thermal deterioration of the exhaust system parts.
Note that the control device 13 can set one of the increase coefficient KMR1 and the holding time RET as a fixed value and change the other according to the water temperature TW.
前述の図２−図６に示した第１実施形態において、制御装置１３は、増量係数ＫＭＲ１（応答調整用の空燃比ＡＦ１）の保持時間ＲＥＴが経過したときに、増量係数ＫＭＲをＫＭＲ１からＫＭＲ２にシフトさせ、空燃比を空燃比ＡＦ１から空燃比ＡＦ２にステップ的に切り替える。
これに対し、制御装置１３が、増量係数ＫＭＲをＫＭＲ１からＫＭＲ２に向けて徐々に変化させることで、空燃比が空燃比ＡＦ１から空燃比ＡＦ２に徐々に近づくようにし、更に、ＫＭＲ１からＫＭＲ２に向けての増量係数ＫＭＲの変化速度、換言すれば、空燃比ＡＦ１から空燃比ＡＦ２に向けての空燃比の変化速度を、水温ＴＷに応じて変更する構成とすることができる。
In the first embodiment shown in FIGS. 2 to 6, the control device 13 changes the increase coefficient KMR from KMR1 to KMR2 when the retention time RET of the increase coefficient KMR1 (response adjustment air-fuel ratio AF1) has elapsed. And the air-fuel ratio is switched stepwise from the air-fuel ratio AF1 to the air-fuel ratio AF2.
On the other hand, the controller 13 gradually changes the increase coefficient KMR from KMR1 to KMR2, so that the air-fuel ratio gradually approaches the air-fuel ratio AF2 from the air-fuel ratio AF1, and further from KMR1 to KMR2. The rate of change of the increase coefficient KMR, in other words, the rate of change of the air-fuel ratio from the air-fuel ratio AF1 to the air-fuel ratio AF2 can be changed according to the water temperature TW.
以下では、制御装置１３が増量係数ＫＭＲをＫＭＲ１からＫＭＲ２に向けて徐々に変化させる構成とした第２実施形態を説明する。
図７は、第２実施形態における制御装置１３による燃料増量処理の流れ（空燃比制御部としての演算機能）を示すフローチャートである。
図８は、第２実施形態における機関負荷の変化に対する空燃比、排気温度ＴＥＸ、粒子状物質の排出量の変化を例示する。
Hereinafter, a second embodiment in which the control device 13 is configured to gradually change the increase coefficient KMR from KMR1 to KMR2 will be described.
FIG. 7 is a flowchart showing the flow of fuel increase processing (calculation function as an air-fuel ratio control unit) by the control device 13 in the second embodiment.
FIG. 8 exemplifies changes in the air-fuel ratio, the exhaust gas temperature TEX, and the particulate matter discharge amount with respect to changes in the engine load in the second embodiment.
制御装置１３は、図７のフローチャートのステップＳ２０１−ステップＳ２１３において、図２のフローチャートのステップＳ１０１−ステップＳ１１３と同じ処理を実施し、図７のフローチャートのステップＳ２２０，ステップＳ２２１において、図２のフローチャートのステップＳ１１５，ステップＳ１１６と同じ処理を実施する。
そこで、第１実施形態及び第２実施形態に共通するステップの処理内容については説明を省略し、第２実施形態における特徴部分であるステップＳ２１４−ステップＳ２１９の処理内容を以下で詳述する。
The control device 13 performs the same processing as Step S101 to Step S113 of the flowchart of FIG. 2 in Step S201 to Step S213 of the flowchart of FIG. 7, and in Step S220 and Step S221 of the flowchart of FIG. Steps S115 and S116 are performed in the same manner.
Therefore, the description of the processing contents of steps common to the first embodiment and the second embodiment is omitted, and the processing contents of steps S214 to S219, which are characteristic parts in the second embodiment, will be described in detail below.
制御装置１３は、ステップＳ２１２で保持時間ＲＥＴの経過を検出してステップＳ２１４に進むと、水温ＴＷを読み込む。
次いで、制御装置１３は、ステップＳ２１５に進み、増量係数ＫＭＲをＫＭＲ１からＫＭＲ２に向けて増加させるときの速度ΔＫＭＲ（単位時間当たりの増量係数ＫＭＲのステップ増加量）を水温ＴＷに応じて設定する。
When the control device 13 detects the elapse of the holding time RET in step S212 and proceeds to step S214, it reads the water temperature TW.
Next, the control device 13 proceeds to step S215, and sets the speed ΔKMR (step increase amount of the increase coefficient KMR per unit time) when increasing the increase coefficient KMR from KMR1 to KMR2 according to the water temperature TW.
図９は、増量係数ＫＭＲの増加速度ΔＫＭＲと水温ＴＷとの相関を例示する。
制御装置１３は、図９に示すように、水温ＴＷが低いほど増加速度ΔＫＭＲを遅く設定し、増量係数ＫＭＲがＫＭＲ１からＫＭＲ２にまで増加する（空燃比が空燃比ＡＦ１から空燃比ＡＦ２までリッチ化する）のが遅れるようにする。
FIG. 9 illustrates the correlation between the increase rate ΔKMR of the increase coefficient KMR and the water temperature TW.
As shown in FIG. 9, the control device 13 sets the increase rate ΔKMR slower as the water temperature TW is lower, and the increase coefficient KMR increases from KMR1 to KMR2 (the air-fuel ratio is enriched from the air-fuel ratio AF1 to the air-fuel ratio AF2). To be late).
制御装置１３は、次いでステップＳ２１６に進んで増量係数ＫＭＲをＫＭＲ１から増加速度ΔＫＭＲで徐々に増加させる処理を実施し、増量係数ＫＭＲをＫＭＲ１からＫＭＲ２に向けて増加させる過渡状態での増量係数ＫＭＲ３（ＫＭＲ３＞ＫＭＲ１）を設定する。
そして、制御装置１３は、ステップＳ２１７で、ステップＳ２１６での演算で求めた増量係数ＫＭＲ３と、高負荷域で排気温度の上昇を抑制するための増量係数ＫＭＲ２とを比較する。
Next, the control device 13 proceeds to step S216, performs a process of gradually increasing the increase coefficient KMR from KMR1 at the increase rate ΔKMR, and increases the increase coefficient KMR from KMR1 to KMR2 in the transient state. KMR3> KMR1) is set.
In step S217, the control device 13 compares the increase coefficient KMR3 obtained by the calculation in step S216 with the increase coefficient KMR2 for suppressing an increase in the exhaust temperature in the high load range.
増量係数ＫＭＲ３が増量係数ＫＭＲ２よりも小さい場合、増量係数ＫＭＲをＫＭＲ１からＫＭＲ２に向けて徐々に増加させる過渡状態（図８の時刻ｔ３から時刻ｔ４の間）であるので、制御装置１３は、ステップＳ２１８に進んで、燃料噴射量の増量補正に用いる増量係数ＫＭＲをＫＭＲ３に設定する。
一方、増量係数ＫＭＲ３が増量係数ＫＭＲ２以上になると、制御装置１３は、ステップＳ２１９に進み、燃料噴射量の増量補正に用いる増量係数ＫＭＲをＫＭＲ２に設定する（図８の時刻ｔ４）。
When the increase coefficient KMR3 is smaller than the increase coefficient KMR2, the controller 13 is in a transient state (between time t3 and time t4 in FIG. 8) in which the increase coefficient KMR is gradually increased from KMR1 to KMR2. Proceeding to S218, the increase coefficient KMR used for correcting the increase in the fuel injection amount is set to KMR3.
On the other hand, when the increase coefficient KMR3 becomes equal to or greater than the increase coefficient KMR2, the control device 13 proceeds to step S219, and sets the increase coefficient KMR used for increasing the fuel injection amount to KMR2 (time t4 in FIG. 8).
つまり、制御装置１３は、増量係数ＫＭＲをＫＭＲ１に保持時間ＲＥＴだけ保持した後は、水温ＴＷが低いほどより遅い速度で増量係数ＫＭＲをＫＭＲ１から徐々に増加させ、増量係数ＫＭＲがＫＭＲ２に達すると、その後は増量係数ＫＭＲをＫＭＲ２に維持させる。
換言すれば、制御装置１３は、空燃比を保持時間ＲＥＴ（図８の時刻ｔ２から時刻ｔ３の間）だけ空燃比ＡＦ１（ＡＦ１＜14.7）に保持した後、水温ＴＷが低いほどより遅い速度で空燃比ＡＦ１から徐々にリッチ方向に変化させ、空燃比が空燃比ＡＦ２（ＡＦ２＜ＡＦ１＜14.7）に達すると（図８の時刻ｔ４）、その後（図８の時刻ｔ４以降）は、空燃比を空燃比ＡＦ２に維持する。
That is, after holding the increase coefficient KMR in KMR1 for the holding time RET, the control device 13 gradually increases the increase coefficient KMR from KMR1 at a slower speed as the water temperature TW is lower, and when the increase coefficient KMR reaches KMR2. Thereafter, the increase coefficient KMR is maintained at KMR2.
In other words, the control device 13 holds the air-fuel ratio at the air-fuel ratio AF1 (AF1 <14.7) for the holding time RET (between time t2 and time t3 in FIG. 8), and then at a slower speed as the water temperature TW decreases. When the air-fuel ratio is gradually changed from the air-fuel ratio AF1 to reach the air-fuel ratio AF2 (AF2 <AF1 <14.7) (time t4 in FIG. 8), thereafter (after time t4 in FIG. 8), the air-fuel ratio is decreased. The air-fuel ratio AF2 is maintained.
制御装置１３が、第１実施形態のように、空燃比を空燃比ＡＦ１（ＡＦ１＜14.7）に保持時間ＲＥＴだけ保持した後に、空燃比を空燃比ＡＦ２にまでステップ的にリッチ化させると、排気中の粒子状物質が急に増える可能性がある。
これに対し、第２実施形態では、制御装置１３が、空燃比ＡＦ１から空燃比ＡＦ２にまで徐々にリッチ化させるように制御し、かつ、空燃比ＡＦ１から空燃比ＡＦ２に向かう速度を水温ＴＷが低いほど遅くするので、排気温度ＴＥＸが排気系部品の保護のための上限排気温度ＴＥＸmaxに達することを抑制しつつ、粒子状物質の排出を可及的に抑えることができる（図８参照）。
When the control device 13 holds the air-fuel ratio in the air-fuel ratio AF1 (AF1 <14.7) for the holding time RET and then enriches the air-fuel ratio stepwise to the air-fuel ratio AF2 as in the first embodiment, There may be a sudden increase in particulate matter.
On the other hand, in the second embodiment, the control device 13 performs control so that the air-fuel ratio AF1 gradually increases from the air-fuel ratio AF1 to the air-fuel ratio AF2, and the water temperature TW changes the speed from the air-fuel ratio AF1 to the air-fuel ratio AF2. Since the lower the speed is, the lower the exhaust temperature TEX is, and the exhaust of particulate matter can be suppressed as much as possible while suppressing the exhaust temperature TEX from reaching the upper limit exhaust temperature TEXmax for protecting the exhaust system parts (see FIG. 8).
前述した第１実施形態及び第２実施形態において、制御装置１３は、内燃機関１の運転温度を代表する状態量として水温ＴＷを用い、水温ＴＷが低いほど高負荷域での空燃比リッチ化の変化応答を遅らせる。
しかし、内燃機関１の運転温度として水温ＴＷを用いる構成に限定されず、制御装置１３は、排気温度ＴＥＸに基づき高負荷域での空燃比リッチ化の変化応答を設定できる。
In the first embodiment and the second embodiment described above, the control device 13 uses the water temperature TW as a state quantity representative of the operating temperature of the internal combustion engine 1, and the lower the water temperature TW, the richer the air-fuel ratio in the high load region. Delay change response.
However, the control device 13 is not limited to the configuration using the water temperature TW as the operating temperature of the internal combustion engine 1, and can set the change response of the air-fuel ratio enrichment in the high load region based on the exhaust temperature TEX.
以下では、制御装置１３が、排気温度ＴＥＸに基づき高負荷域での空燃比リッチ化の変化応答を設定する構成とした第３実施形態を説明する。
図１０は、第３実施形態における制御装置１３による燃料増量処理の流れ（空燃比制御部としての演算機能）を示すフローチャートである。
Hereinafter, a description will be given of a third embodiment in which the control device 13 is configured to set the change response of the air-fuel ratio enrichment in the high load region based on the exhaust gas temperature TEX.
FIG. 10 is a flowchart showing the flow of fuel increase processing (calculation function as an air-fuel ratio control unit) by the control device 13 in the third embodiment.
図１０のフローチャートは、第１実施形態を示す図２のフローチャートの水温ＴＷに関わる処理を、排気温度ＴＥＸに関わる処理に置き換えた点が異なるが、高負荷域における基本的な増量補正処理の流れは共通し、図１０のフローチャートのステップＳ３０１−ステップＳ３１６は、図２のフローチャートのステップＳ１０１−ステップＳ１１６にそのまま対応する。
そこで、以下では、排気温度ＴＥＸに関わる処理であるステップＳ３０４−ステップＳ３０５（遅延時間ＤＴの設定処理）、ステップＳ３０７−ステップＳ３０９（増量係数ＫＭＲ１及び保持時間ＲＥＴの設定処理）を詳述する。
The flowchart of FIG. 10 is different in that the process related to the water temperature TW in the flowchart of FIG. 2 showing the first embodiment is replaced with the process related to the exhaust temperature TEX, but the flow of basic increase correction processing in a high load region is different. Are common, and steps S301 to S316 in the flowchart of FIG. 10 correspond directly to steps S101 to S116 in the flowchart of FIG.
Therefore, in the following, step S304 to step S305 (delay time DT setting process) and step S307 to step S309 (increase coefficient KMR1 and holding time RET setting process), which are processes related to the exhaust gas temperature TEX, will be described in detail.
図１０のフローチャートにおいて、制御装置１３は、ステップＳ３０４で、排気温度ＴＥＸを読み込み、次のステップＳ３０５（遅延時間設定部）で、高負荷域になってから燃料増量処理を開始させるまでの遅延時間ＤＴを排気温度ＴＥＸに基づき設定する。
なお、内燃機関１が排気温度センサ１６を備えない場合、制御装置１３は、ステップＳ３０５で排気温度センサ１６による排気温度ＴＥＸの検出値に代えて排気温度ＴＥＸの推定値を用いることができる。この場合、制御装置１３は、ステップＳ３０４で、水温ＴＷ、吸入空気量、スロットル開度、機関負荷、機関回転速度などの機関運転状態から排気温度ＴＥＸを推定する処理を実施する。
In the flowchart of FIG. 10, the control device 13 reads the exhaust gas temperature TEX in step S304, and in the next step S305 (delay time setting unit), the delay time until the fuel increase process is started after the high load region is reached. DT is set based on the exhaust temperature TEX.
When the internal combustion engine 1 does not include the exhaust temperature sensor 16, the control device 13 can use the estimated value of the exhaust temperature TEX instead of the detected value of the exhaust temperature TEX by the exhaust temperature sensor 16 in step S305. In this case, in step S304, the control device 13 performs a process of estimating the exhaust temperature TEX from the engine operating state such as the water temperature TW, the intake air amount, the throttle opening, the engine load, and the engine speed.
制御装置１３は、ステップＳ３０５において、排気系部品の保護のための上限排気温度ＴＥＸmaxと排気温度ＴＥＸの検出値（又は排気温度ＴＥＸの推定値）との差ΔＴＥＸ（ΔＴＥＸ＝ＴＥＸmax−ＴＥＸ）に基づき、遅延時間ＤＴを設定する。
図１１は、遅延時間ＤＴと排気温度差ΔＴＥＸとの相関を例示する図である。
In step S305, the control device 13 is based on the difference ΔTEX (ΔTEX = TEXmax−TEX) between the upper limit exhaust temperature TEXmax for protecting the exhaust system components and the detected value of the exhaust temperature TEX (or the estimated value of the exhaust temperature TEX). The delay time DT is set.
FIG. 11 is a diagram illustrating the correlation between the delay time DT and the exhaust gas temperature difference ΔTEX.
排気温度差ΔＴＥＸが大きい場合（排気温度ＴＥＸが低い場合）は、排気温度ＴＥＸが上限排気温度ＴＥＸmaxに達するまでの余裕が大きく、排温上昇を抑制するための空燃比のリッチ化をより遅らせることができる。逆に、排気温度差ΔＴＥＸが小さいと、排気温度ＴＥＸが直ぐに上限排気温度ＴＥＸmaxに達してしまい、排温上昇を抑制するための空燃比のリッチ化を急ぐ必要がある。
そこで、制御装置１３は、ステップＳ３０５において、図１１に示したように、排気温度差ΔＴＥＸが大きいほど、換言すれば、そのときの排気温度ＴＥＸが低いほど、遅延時間ＤＴをより長い時間に設定する。
When the exhaust gas temperature difference ΔTEX is large (when the exhaust gas temperature TEX is low), there is a large margin until the exhaust gas temperature TEX reaches the upper limit exhaust gas temperature TEXmax, and the enrichment of the air-fuel ratio for suppressing the exhaust gas temperature rise is further delayed. Can do. Conversely, if the exhaust gas temperature difference ΔTEX is small, the exhaust gas temperature TEX immediately reaches the upper limit exhaust gas temperature TEXmax, and it is necessary to urgently enrich the air-fuel ratio in order to suppress the exhaust gas temperature rise.
Therefore, in step S305, the control device 13 sets the delay time DT to a longer time as the exhaust temperature difference ΔTEX is larger, in other words, as the exhaust temperature TEX at that time is lower, as shown in FIG. To do.
次に、第３実施形態における増量係数ＫＭＲ１及び保持時間ＲＥＴの設定処理を詳述する。
制御装置１３は、ステップＳ３０７で、排気温度ＴＥＸの検出値を読み込むか、又は、排気温度ＴＥＸの推定を行い、次ステップＳ３０８では、排気温度ＴＥＸの検出値（又は排気温度ＴＥＸの推定値）に基づき、増量係数ＫＭＲ１を設定する。
Next, the setting process of the increase coefficient KMR1 and the holding time RET in the third embodiment will be described in detail.
In step S307, the control device 13 reads the detected value of the exhaust temperature TEX or estimates the exhaust temperature TEX. In the next step S308, the detected value of the exhaust temperature TEX (or the estimated value of the exhaust temperature TEX) is obtained. Based on this, an increase coefficient KMR1 is set.
制御装置１３は、ステップＳ３０８において、排気系部品の保護のための上限排気温度ＴＥＸmaxと排気温度ＴＥＸの検出値（又は排気温度ＴＥＸの推定値）との差ΔＴＥＸ（ΔＴＥＸ＝ＴＥＸmax−ＴＥＸ）に基づき、増量係数ＫＭＲ１を設定する。
図１２は、増量係数ＫＭＲ１と排気温度差ΔＴＥＸとの相関を例示する図である。
In step S308, the control device 13 is based on the difference ΔTEX (ΔTEX = TEXmax−TEX) between the upper limit exhaust temperature TEXmax for protecting the exhaust system components and the detected value of the exhaust temperature TEX (or the estimated value of the exhaust temperature TEX). The increase coefficient KMR1 is set.
FIG. 12 is a diagram illustrating the correlation between the increase coefficient KMR1 and the exhaust gas temperature difference ΔTEX.
排気温度差ΔＴＥＸが大きい場合（排気温度ＴＥＸが低い場合）は、排気温度ＴＥＸが上限排気温度ＴＥＸmaxに達するまでの余裕が大きいため、排温上昇を抑制するための空燃比のリッチ化要求が低く、排気温度差ΔＴＥＸが小さい場合に比べてリッチ化を抑えることができる。
そこで、制御装置１３は、ステップＳ３０８において、図１２に示したように、排気温度差ΔＴＥＸが大きいほど、換言すれば、そのときの排気温度ＴＥＸが低いほど、増量係数ＫＭＲ１（ＫＭＲ１＞1.0）をより小さい値に設定する。
When the exhaust gas temperature difference ΔTEX is large (when the exhaust gas temperature TEX is low), there is a large margin until the exhaust gas temperature TEX reaches the upper exhaust gas temperature TEXmax. Further, the enrichment can be suppressed as compared with the case where the exhaust gas temperature difference ΔTEX is small.
Therefore, in step S308, as shown in FIG. 12, the control device 13 increases the increase coefficient KMR1 (KMR1> 1.0) as the exhaust temperature difference ΔTEX is larger, in other words, as the exhaust temperature TEX at that time is lower. Set to a smaller value.
更に、制御装置１３は、次のステップＳ３０９で、排気温度差ΔＴＥＸに基づき保持時間ＲＥＴを設定する。
図１３は、保持時間ＲＥＴと排気温度差ΔＴＥＸとの相関を例示する図である。
排気温度差ΔＴＥＸが大きい場合（排気温度ＴＥＸが低い場合）は、排気温度ＴＥＸが上限排気温度ＴＥＸmaxに達するまでの余裕が大きく、排温上昇を抑制するための空燃比の更なるリッチ化を遅らせることができる。逆に、排気温度差ΔＴＥＸが小さいと、排気温度ＴＥＸが直ぐに上限排気温度ＴＥＸmaxに達してしまい、排温上昇を抑制するための空燃比の更なるリッチ化を急ぐ必要がある。
Further, in the next step S309, the control device 13 sets the holding time RET based on the exhaust gas temperature difference ΔTEX.
FIG. 13 is a diagram illustrating a correlation between the holding time RET and the exhaust gas temperature difference ΔTEX.
When the exhaust gas temperature difference ΔTEX is large (when the exhaust gas temperature TEX is low), there is a large margin until the exhaust gas temperature TEX reaches the upper exhaust gas temperature TEXmax, and further enrichment of the air-fuel ratio for suppressing the exhaust gas temperature is delayed. be able to. On the contrary, if the exhaust gas temperature difference ΔTEX is small, the exhaust gas temperature TEX immediately reaches the upper limit exhaust gas temperature TEXmax, and it is necessary to urgently further enrich the air-fuel ratio in order to suppress the exhaust gas temperature rise.
そこで、制御装置１３は、ステップＳ３０９において、図１３に示したように、排気温度差ΔＴＥＸが大きいほど、換言すれば、そのときの排気温度ＴＥＸが低いほど、保持時間ＲＥＴをより長い時間に設定し、空燃比をＡＦ１からＡＦ２にまでリッチ化させるまでの時間を遅らせる。
このように、排気温度差ΔＴＥＸに基づき高負荷域での燃料増量処理の応答を設定する構成であれば、より高い精度で燃料増量処理（空燃比のリッチ化処理）を実施でき、空燃比のリッチ化に伴う排気性状（粒子状物質量）の悪化を可及的に抑えることができる。
Therefore, in step S309, as shown in FIG. 13, the control device 13 sets the holding time RET to a longer time as the exhaust temperature difference ΔTEX is larger, in other words, as the exhaust temperature TEX at that time is lower. Then, the time until the air-fuel ratio is enriched from AF1 to AF2 is delayed.
As described above, if the response of the fuel increase process in the high load region is set based on the exhaust gas temperature difference ΔTEX, the fuel increase process (air-fuel ratio enrichment process) can be performed with higher accuracy. Deterioration of exhaust properties (particulate matter amount) accompanying enrichment can be suppressed as much as possible.
上記第３実施形態の増量処理における、増量係数ＫＭＲ１から増量係数ＫＭＲ２にステップ的に切り替える構成に代えて、増量係数ＫＭＲ１から増量係数ＫＭＲ２に向けて増量係数ＫＭＲを徐々に増加させる構成とし、制御装置１３が、増量係数ＫＭＲの増加速度を排気温度ＴＥＸ（排気温度差ΔＴＥＸ）に基づき設定するよう構成することができる。 In the increase processing of the third embodiment, instead of the configuration in which the increase coefficient KMR1 is switched to the increase coefficient KMR2 stepwise, the increase coefficient KMR is gradually increased from the increase coefficient KMR1 toward the increase coefficient KMR2. 13 can be configured to set the increase rate of the increase coefficient KMR based on the exhaust temperature TEX (exhaust temperature difference ΔTEX).
係る構成とした第４実施形態を以下で説明する。
図１４のフローチャートは、図１０のフローチャートに示した処理の流れに、増量係数ＫＭＲ１から増量係数ＫＭＲ２に向けて排気温度ＴＥＸに応じた速度で増量係数ＫＭＲを徐々に増加させる処理（ステップＳ４１４−ステップＳ４１９）を付加した点が異なり、更に、ステップＳ４１４−ステップＳ４１９は、図７に示した第２実施形態のステップＳ２１４−ステップＳ２１９に対し、増量係数ＫＭＲの増加速度が排気温度差ΔＴＥＸに基づき設定される点が異なる。
A fourth embodiment having such a configuration will be described below.
The flowchart of FIG. 14 is a process of gradually increasing the increase coefficient KMR from the increase coefficient KMR1 toward the increase coefficient KMR2 at a speed corresponding to the exhaust temperature TEX (step S414-step). Step S419 to Step S419 is different from Step S214 to Step S219 of the second embodiment shown in FIG. 7 in that the increase rate of the increase coefficient KMR is set based on the exhaust gas temperature difference ΔTEX. Is different.
そこで、以下では、既述した処理についての詳細な説明を省略し、制御装置１３が、増量係数ＫＭＲの増加速度を排気温度差ΔＴＥＸに基づき設定する処理を詳述する。
制御装置１３は、ステップＳ４１４で、排気温度ＴＥＸの検出値を読み込むか、又は、排気温度ＴＥＸの推定を行い、次ステップＳ４１５では、増量係数ＫＭＲをＫＭＲ１からＫＭＲ２に向けて増加させるときの速度ΔＫＭＲを排気温度ＴＥＸの検出値（又は排気温度ＴＥＸの推定値）に基づき設定する。
Therefore, in the following, detailed description of the processing described above will be omitted, and processing in which the control device 13 sets the increase rate of the increase coefficient KMR based on the exhaust gas temperature difference ΔTEX will be described in detail.
In step S414, the control device 13 reads the detected value of the exhaust gas temperature TEX or estimates the exhaust gas temperature TEX, and in the next step S415, the speed ΔKMR when increasing the increase coefficient KMR from KMR1 to KMR2. Is set based on the detected value of the exhaust temperature TEX (or the estimated value of the exhaust temperature TEX).
制御装置１３は、ステップＳ４１５において、排気系部品の保護のための上限排気温度ＴＥＸmaxと排気温度ＴＥＸの検出値（又は排気温度ＴＥＸの推定値）との差ΔＴＥＸ（ΔＴＥＸ＝ＴＥＸmax−ＴＥＸ）に基づき、増量係数ＫＭＲの増加速度ΔＫＭＲを設定する。
図１５は、増量係数ＫＭＲの増加速度ΔＫＭＲと排気温度差ΔＴＥＸとの相関を例示する。
In step S415, the control device 13 is based on the difference ΔTEX (ΔTEX = TEXmax−TEX) between the upper limit exhaust temperature TEXmax for protecting the exhaust system components and the detected value of the exhaust temperature TEX (or the estimated value of the exhaust temperature TEX). The increase rate ΔKMR of the increase coefficient KMR is set.
FIG. 15 illustrates the correlation between the increase rate ΔKMR of the increase coefficient KMR and the exhaust gas temperature difference ΔTEX.
制御装置１３は、図１５に示すように、排気温度差ΔＴＥＸが大きいほど、換言すれば、排気温度ＴＥＸが低いほど、増加速度ΔＫＭＲを小さくする。
排気温度差ΔＴＥＸが大きい場合は、排気温度ＴＥＸが上限排気温度ＴＥＸmaxに達するまでの余裕が大きく、排温上昇を抑制するための空燃比のリッチ化要求が低いから、空燃比ＡＦ２にまでリッチ化するのを遅らせることができる。
As shown in FIG. 15, the control device 13 decreases the increase rate ΔKMR as the exhaust temperature difference ΔTEX is larger, in other words, as the exhaust temperature TEX is lower.
When the exhaust gas temperature difference ΔTEX is large, there is a large margin until the exhaust gas temperature TEX reaches the upper limit exhaust gas temperature TEXmax, and the demand for enriching the air-fuel ratio to suppress the exhaust temperature rise is low. Can be delayed.
そして、制御装置１３が、排気温度ＴＥＸの低いときに（冷機状態で）空燃比ＡＦ２に向けてのリッチ化を遅らせることで、燃料増量処理に伴う排気性状（粒子状物質の排出量）の悪化を抑えることができ、更に、排気温度ＴＥＸ（排気温度差ΔＴＥＸ）に基づき空燃比ＡＦ２に向けてのリッチ化速度を設定することで、空燃比のリッチ化を可及的に抑えつつ排気温度ＴＥＸが上限排気温度ＴＥＸmaxに達することを抑制できる。 The control device 13 delays the enrichment toward the air-fuel ratio AF2 when the exhaust temperature TEX is low (in the cold state), thereby deteriorating the exhaust property (particulate matter discharge amount) accompanying the fuel increase processing. Furthermore, by setting the enrichment speed toward the air-fuel ratio AF2 based on the exhaust temperature TEX (exhaust temperature difference ΔTEX), the exhaust temperature TEX is suppressed while suppressing the enrichment of the air-fuel ratio as much as possible. Can be prevented from reaching the upper exhaust temperature TEXmax.
上記実施形態で説明した各技術的思想は、矛盾が生じない限りにおいて、適宜組み合わせて使用することができる。
また、好ましい実施形態を参照して本発明の内容を具体的に説明したが、本発明の基本的技術思想及び教示に基づいて、当業者であれば、種々の変形態様を採り得ることは自明である。
The technical ideas described in the above embodiments can be used in appropriate combination as long as no contradiction arises.
Although the contents of the present invention have been specifically described with reference to preferred embodiments, it is obvious that those skilled in the art can take various modifications based on the basic technical idea and teachings of the present invention. It is.
例えば、制御装置１３は、遅延時間ＤＴを水温ＴＷに応じて変更する一方で、増量係数ＫＭＲ１、保持時間ＲＥＴ、増加速度ΔＫＭＲを排気温度ＴＥＸ（排気温度差ΔＴＥＸ）に応じて変更するなど、水温ＴＷに応じた増量応答の設定と、排気温度ＴＥＸに応じた増量応答の設定とを併用することができる。
また、制御装置１３は、高負荷域での燃料噴射量の増量補正中に水温ＴＷ又は排気温度ＴＥＸが減少変化したときに、増量を減らす（空燃比をリーン化方向に変化させる）処理を実施することができる。
For example, the control device 13 changes the delay time DT according to the water temperature TW, while changing the increase coefficient KMR1, the holding time RET, and the increase speed ΔKMR according to the exhaust temperature TEX (exhaust temperature difference ΔTEX). The setting of the increase response according to the TW and the setting of the increase response according to the exhaust gas temperature TEX can be used together.
In addition, the control device 13 performs a process of reducing the increase (changing the air-fuel ratio in the leaning direction) when the water temperature TW or the exhaust gas temperature TEX is decreased during the increase correction of the fuel injection amount in the high load range. can do.
また、上記実施形態において、制御装置１３は、高負荷域での空燃比のリッチ方向への変化応答を設定するのに用いる内燃機関１の運転温度として、水温ＴＷと排気温度ＴＥＸとの少なくとも一方を用いるが、これらに代えて若しくはこれらとともに、吸気温度、外気温度、潤滑油温度、触媒温度などを用いることができる。
また、制御装置１３は、高負荷域での空燃比のリッチ方向への変化応答を設定する処理において、内燃機関１の運転温度及び内燃機関１の運転状態（機関負荷、機関回転速度など）に応じて変化応答を変更することができる。
In the above-described embodiment, the control device 13 uses at least one of the water temperature TW and the exhaust gas temperature TEX as the operating temperature of the internal combustion engine 1 used for setting the change response in the rich direction of the air-fuel ratio in the high load range. However, instead of or together with these, intake air temperature, outside air temperature, lubricating oil temperature, catalyst temperature, and the like can be used.
Further, the control device 13 sets the operating temperature of the internal combustion engine 1 and the operating state (engine load, engine speed, etc.) of the internal combustion engine 1 in the process of setting the response to change in the rich direction of the air-fuel ratio in the high load region. The change response can be changed accordingly.
また、制御装置１３は、遅延時間ＤＴが経過したときから高負荷用のリッチ空燃比ＡＦ２に向けて空燃比を徐々にリッチ化させる構成とし、更に、遅延時間ＤＴが経過したときからのリッチ方向への空燃比の変化速度を、内燃機関１の運転温度が低いほど遅く設定することができる。
つまり、制御装置１３は、遅延時間ＤＴが経過してから保持時間ＲＥＴだけ空燃比を空燃比ＡＦ１に保持する構成に限定されず、遅延時間ＤＴが経過した時点から徐々に空燃比をリッチ化させて高負荷用のリッチ空燃比に到達させることができる。
Further, the control device 13 is configured to gradually enrich the air-fuel ratio toward the high load rich air-fuel ratio AF2 after the delay time DT has elapsed, and further to the rich direction from when the delay time DT has elapsed. The rate of change of the air-fuel ratio to can be set slower as the operating temperature of the internal combustion engine 1 is lower.
That is, the control device 13 is not limited to the configuration in which the air-fuel ratio is held at the air-fuel ratio AF1 only for the holding time RET after the delay time DT has elapsed, and the air-fuel ratio is gradually enriched from the time when the delay time DT has elapsed. Thus, the rich air-fuel ratio for high load can be reached.
また、内燃機関１が、例えば特開２０１７−４０５６３号公報に開示されるような粒子状物質検出センサを備える場合、制御装置１３は、粒子状物質検出センサによって検出された粒子状物質の量及び内燃機関１の運転温度に基づき、空燃比のリッチ方向への変化応答を変更することができる。
また、制御装置１３は、内燃機関１の運転温度に基づく変化応答の設定特性を、粒子状物質検出センサによって検出された粒子状物質の量に基づき修正する学習処理を実施することができる。
In addition, when the internal combustion engine 1 includes a particulate matter detection sensor as disclosed in, for example, Japanese Patent Application Laid-Open No. 2017-40563, the control device 13 determines the amount of particulate matter detected by the particulate matter detection sensor and Based on the operating temperature of the internal combustion engine 1, the change response of the air-fuel ratio in the rich direction can be changed.
Further, the control device 13 can perform a learning process for correcting the setting characteristic of the change response based on the operating temperature of the internal combustion engine 1 based on the amount of particulate matter detected by the particulate matter detection sensor.
また、制御装置１３は、例えば、増量係数ＫＭＲを加重平均した結果に基づき燃料噴射量を増量補正する加重平均演算部を備え、係る加重平均演算部の重み付けを、高負荷域で内燃機関１の運転温度（水温ＴＷ、排気温度ＴＥＸなど）に応じて変更することで、空燃比のリッチ方向への変化応答を変更する構成とすることができる。
つまり、制御装置１３が、高負荷域で空燃比のリッチ方向への変化応答を変更する処理は、増量係数ＫＭＲの保持や増量係数ＫＭＲを第１規定値から第２規定値に向けて変化させる速度の制御に限定されず、応答を制御する公知の処理を適宜採用できる。
In addition, the control device 13 includes a weighted average calculation unit that increases and corrects the fuel injection amount based on the result of weighted averaging of the increase coefficient KMR, for example, and weights the weighted average calculation unit in the high load range. By changing according to the operating temperature (water temperature TW, exhaust gas temperature TEX, etc.), it is possible to change the change response of the air-fuel ratio in the rich direction.
That is, the process in which the control device 13 changes the change response of the air-fuel ratio in the rich direction in the high load region holds the increase coefficient KMR or changes the increase coefficient KMR from the first specified value toward the second specified value. It is not limited to the speed control, and a known process for controlling the response can be appropriately employed.
ここで、上述した実施形態から把握し得る技術的思想について、以下に記載する。
内燃機関の制御装置は、その一態様として、内燃機関の負荷が高負荷域になったときに前記内燃機関の空燃比をリッチ方向に変化させる空燃比制御部を備え、
前記空燃比制御部は、
前記内燃機関の負荷が高負荷域になった後に遅延時間が経過してから、空燃比をリッチ方向に変化させる処理を開始する遅延処理部と、
前記遅延時間を前記内燃機関の運転温度が低いほどより長く変更する遅延時間設定部と、
前記空燃比をリッチ方向に変化させる処理を開始した後の空燃比のリッチ方向への変化応答を、前記内燃機関の運転温度が低いほどより遅くする応答設定部と、
を含み、
前記応答設定部は、
前記遅延時間が経過したときに空燃比を、理論空燃比よりもリッチで13.0以上である応答調整用のリッチ空燃比にまでシフトさせ、前記応答調整用のリッチ空燃比を設定時間だけ保持させた後、空燃比を前記応答調整用のリッチ空燃比よりもリッチである高負荷用のリッチ空燃比に制御し、
前記応答調整用のリッチ空燃比を前記内燃機関の運転温度が低いほどより大きくする処理と、前記設定時間を前記内燃機関の運転温度が低いほどより長くする処理との少なくとも一方を実施する。
Here, the technical idea that can be understood from the above-described embodiment will be described below.
The internal combustion engine control apparatus includes, as one aspect thereof, an air-fuel ratio control unit that changes the air-fuel ratio of the internal combustion engine in a rich direction when the load of the internal combustion engine is in a high load range,
The air-fuel ratio controller is
A delay processing unit for starting a process of changing the air-fuel ratio in a rich direction after a delay time has elapsed after the load of the internal combustion engine has become a high load range;
A delay time setting unit that changes the delay time longer as the operating temperature of the internal combustion engine is lower;
A response setting unit that makes the change response in the rich direction of the air-fuel ratio after starting the process of changing the air-fuel ratio in the rich direction slower as the operating temperature of the internal combustion engine is lower;
Including
The response setting unit
When the delay time has elapsed, the air-fuel ratio is shifted to a rich air-fuel ratio for response adjustment that is richer than the theoretical air-fuel ratio and 13.0 or more, and the rich air-fuel ratio for response adjustment is held for a set time. Thereafter, the air-fuel ratio is controlled to a rich air-fuel ratio for high load that is richer than the rich air-fuel ratio for response adjustment,
At least one of a process of increasing the rich air-fuel ratio for response adjustment as the operating temperature of the internal combustion engine is lower and a process of increasing the set time as the operating temperature of the internal combustion engine is lower is performed.
このようにすれば、粒子状物質の排出量を抑制しつつ、排気温度の上昇を抑制できる。内燃機関における粒子状物質の排出量は、空燃比が13.0を下回るリッチ域で増大する傾向があるので、理論空燃比よりもリッチで13.0以上である応答調整用のリッチ空燃比に保持させることで、空燃比のリッチ化による排気温度の上昇抑制効果を得つつ、粒子状物質の排出量を抑制することができる。 If it does in this way, the rise in exhaust temperature can be controlled, suppressing the discharge of particulate matter. Since the discharge amount of particulate matter in an internal combustion engine tends to increase in a rich region where the air-fuel ratio is less than 13.0, by maintaining the rich air-fuel ratio for response adjustment that is richer than the theoretical air-fuel ratio and 13.0 or more In addition, it is possible to suppress the discharge amount of the particulate matter while obtaining the effect of suppressing the increase in the exhaust gas temperature due to the enrichment of the air-fuel ratio.
１…内燃機関、５…燃料噴射弁、１３…制御装置、１５…水温センサ、１６…排気温度センサ DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 5 ... Fuel injection valve, 13 ... Control apparatus, 15 ... Water temperature sensor, 16 ... Exhaust temperature sensor
Claims (7)
前記空燃比制御部は、
前記内燃機関の負荷が高負荷域になった後に遅延時間が経過してから、空燃比をリッチ方向に変化させる処理を開始する遅延処理部と、
前記遅延時間を前記内燃機関の運転温度が低いほどより長く変更する遅延時間設定部と、
前記空燃比をリッチ方向に変化させる処理を開始した後の空燃比のリッチ方向への変化応答を、前記内燃機関の運転温度が低いほどより遅くする応答設定部と、
を含む、内燃機関の制御装置。 An air-fuel ratio controller that changes the air-fuel ratio of the internal combustion engine in a rich direction when the load of the internal combustion engine is in a high load range;
The air-fuel ratio controller is
A delay processing unit for starting a process of changing the air-fuel ratio in a rich direction after a delay time has elapsed after the load of the internal combustion engine has become a high load range;
A delay time setting unit that changes the delay time longer as the operating temperature of the internal combustion engine is lower;
A response setting unit that makes the change response in the rich direction of the air-fuel ratio after starting the process of changing the air-fuel ratio in the rich direction slower as the operating temperature of the internal combustion engine is lower;
A control device for an internal combustion engine, comprising:
前記遅延時間が経過したときに空燃比を設定値だけリッチ方向にシフトさせ、当該シフト後の空燃比を設定時間だけ保持させた後、空燃比を更にリッチ方向に変化させ、
前記設定値を前記内燃機関の運転温度が低いほどより小さくする処理と、前記設定時間を前記内燃機関の運転温度が低いほどより長くする処理との少なくとも一方を実施する、
請求項１記載の内燃機関の制御装置。 The response setting unit
When the delay time has elapsed, the air-fuel ratio is shifted in the rich direction by a set value, the air-fuel ratio after the shift is held for the set time, and then the air-fuel ratio is further changed in the rich direction,
Performing at least one of a process of making the set value smaller as the operating temperature of the internal combustion engine is lower and a process of making the set time longer as the operating temperature of the internal combustion engine is lower,
The control device for an internal combustion engine according to claim 1.
前記設定時間が経過した後に空燃比を更にリッチ方向にシフトさせて高負荷用のリッチ空燃比に制御する、
請求項２記載の内燃機関の制御装置。 The response setting unit
After the set time has elapsed, the air-fuel ratio is further shifted in the rich direction to control the rich air-fuel ratio for high load.
The control device for an internal combustion engine according to claim 2.
前記設定時間が経過した後に空燃比をリッチ方向に設定速度で変化させ、
前記設定速度を前記内燃機関の運転温度が低いほどより遅くする、
請求項２記載の内燃機関の制御装置。 The response setting unit
After the set time has elapsed, the air-fuel ratio is changed in the rich direction at a set speed,
Making the set speed slower as the operating temperature of the internal combustion engine is lower,
The control device for an internal combustion engine according to claim 2.
請求項１から請求項４のいずれか１つに記載の内燃機関の制御装置。 The operating temperature of the internal combustion engine is at least one of a cooling water temperature of the internal combustion engine and an exhaust temperature of the internal combustion engine.
The control device for an internal combustion engine according to any one of claims 1 to 4.
排気温度の推定値又は排気温度の検出値と上限排気温度との差が大きいほど空燃比のリッチ方向への変化応答を遅くする、
請求項５記載の内燃機関の制御装置。 The response setting unit
The greater the difference between the estimated value of the exhaust temperature or the detected value of the exhaust temperature and the upper limit exhaust temperature, the slower the change response in the rich direction of the air-fuel ratio.
The control device for an internal combustion engine according to claim 5.
前記内燃機関の負荷が高負荷域になってからの経過時間が遅延時間に達したか否かを検出するステップと、
前記遅延時間を前記内燃機関の運転温度が低いほどより長く変更するステップと、
前記経過時間が前記遅延時間に達してから前記内燃機関の空燃比をリッチ方向に変化させるステップと、
前記空燃比のリッチ方向への変化応答を前記内燃機関の運転温度が低いほどより遅くするステップと、
を含む、内燃機関の制御方法。 Detecting whether the load of the internal combustion engine is in a high load range;
Detecting whether or not an elapsed time since the load of the internal combustion engine has become a high load range has reached a delay time;
Changing the delay time longer as the operating temperature of the internal combustion engine is lower;
Changing the air-fuel ratio of the internal combustion engine in a rich direction after the elapsed time reaches the delay time;
A step of making the change response in the rich direction of the air-fuel ratio slower as the operating temperature of the internal combustion engine is lower;
A control method for an internal combustion engine, comprising:
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| JP2015094299A (en) * | 2013-11-13 | 2015-05-18 | 日産自動車株式会社 | Fuel injection control device of internal combustion engine |
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| JPS6153431A (en) * | 1984-08-23 | 1986-03-17 | Toyota Motor Corp | Control device for increase of fuel in internal-combustion engine |
| JP2003065111A (en) * | 2001-08-23 | 2003-03-05 | Fuji Heavy Ind Ltd | Fuel injection controller for engine |
| JP2015094299A (en) * | 2013-11-13 | 2015-05-18 | 日産自動車株式会社 | Fuel injection control device of internal combustion engine |
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| JP2020169622A (en) * | 2019-04-04 | 2020-10-15 | マツダ株式会社 | Engine combustion control device |
| JP7283187B2 (en) | 2019-04-04 | 2023-05-30 | マツダ株式会社 | Engine combustion control device |
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