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JP7493885B2 - Control device for internal combustion engine - Google Patents

Control device for internal combustion engine Download PDF

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JP7493885B2
JP7493885B2 JP2020167035A JP2020167035A JP7493885B2 JP 7493885 B2 JP7493885 B2 JP 7493885B2 JP 2020167035 A JP2020167035 A JP 2020167035A JP 2020167035 A JP2020167035 A JP 2020167035A JP 7493885 B2 JP7493885 B2 JP 7493885B2
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無限 太古
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Daihatsu Motor Co Ltd
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  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Description

本発明は、車両に搭載される内燃機関を制御する制御装置に関する。 The present invention relates to a control device that controls an internal combustion engine mounted on a vehicle.

一般に、内燃機関の排気通路には、気筒から排出される排気ガス中に含まれる有害物質HC、CO、NOxを酸化/還元して無害化する三元触媒が装着されている。HC、CO、NOxの全てを効率よく浄化するには、混合気の空燃比をウィンドウと称する理論空燃比近傍の一定範囲に収める必要がある。 In general, a three-way catalyst is installed in the exhaust passage of an internal combustion engine to oxidize/reduce harmful substances HC, CO, and NOx contained in the exhaust gas discharged from the cylinders to render them harmless. In order to efficiently purify all of HC, CO, and NOx , it is necessary to keep the air-fuel ratio of the mixture within a certain range near the theoretical air-fuel ratio, called a window.

そのために、従来より、内燃機関の排気通路に空燃比センサを設置し、空燃比センサの出力信号を参照して、排気通路を流れるガスの空燃比を理論空燃比またはその近傍の目標空燃比にフィードバック制御している。内燃機関の運転制御を司る制御装置たるECU(Electronic Control Unit)は、気筒に吸入される空気(新気)の量に比例する基本噴射量に、ガスの実測空燃比に応じて変動するフィードバック補正係数を乗じることで、インジェクタからの燃料噴射量を決定する(例えば、下記特許文献を参照)。 For this reason, conventionally, an air-fuel ratio sensor is installed in the exhaust passage of an internal combustion engine, and the air-fuel ratio of the gas flowing through the exhaust passage is feedback-controlled to the theoretical air-fuel ratio or a target air-fuel ratio close to the theoretical air-fuel ratio by referring to the output signal of the air-fuel ratio sensor. The ECU (Electronic Control Unit), which is the control device that controls the operation of the internal combustion engine, determines the amount of fuel injected from the injector by multiplying the basic injection amount, which is proportional to the amount of air (fresh air) drawn into the cylinder, by a feedback correction coefficient that varies according to the actual air-fuel ratio of the gas (see, for example, the following patent document).

特開2010-138791号公報JP 2010-138791 A

現行の三元触媒は、内部に酸素を吸蔵する能力を有しており、空燃比リッチのガスが流入するときに蓄えていた酸素を放出し、また空燃比リーンのガスが流入するときに余剰の酸素を吸着する。 Current three-way catalysts have the ability to store oxygen internally, releasing the stored oxygen when rich air-fuel gas flows in, and absorbing excess oxygen when lean air-fuel gas flows in.

この種の触媒は、ある程度ガスの空燃比が変動していないと却って有害物質の浄化能率が低下する性質を帯びている。例えば、一定の車速またはエンジン回転数で車両が定常走行を続け、アクセル開度が安定していると、空燃比が理論空燃比近傍に収束している状態が継続し、(特に、空燃比がリッチまたはリーンに偏った履歴の後に理論空燃比近傍に安定したときに)その帰結として有害物質の排出量が増加することが起こり得る。 This type of catalyst has the property that its purification efficiency for harmful substances decreases if the air-fuel ratio of the gas does not fluctuate to a certain extent. For example, if a vehicle continues to run steadily at a constant vehicle speed or engine speed and the accelerator pedal depression is stable, the air-fuel ratio will continue to converge near the stoichiometric air-fuel ratio, and as a result (especially when the air-fuel ratio stabilizes near the stoichiometric air-fuel ratio after a history of being rich or lean), the amount of harmful substances emitted may increase.

そのような事象を回避するべく、一時的に敢えてガスの空燃比を理論空燃比を跨ぐようにリッチ及びリーンに強制振動させる加振制御を実施し、以て触媒内の酸素吸蔵量を適正化し、触媒による有害物質の浄化能率を高く保つようにしている。 To avoid such an occurrence, vibration control is implemented, which temporarily forces the gas air-fuel ratio to oscillate between rich and lean so that it crosses the theoretical air-fuel ratio, optimizing the amount of oxygen stored in the catalyst and maintaining a high purification efficiency of harmful substances by the catalyst.

だが、空燃比の加振制御により、内燃機関の出力するエンジントルクの大きさは増減する。このエンジントルクの変動が、運転者を含む車両の搭乗者に体感される程度まで大きくなり、車両のNV(Noise and Vibration)性能またはドライバビリティを低下させる懸念がある。 However, the magnitude of the engine torque output by the internal combustion engine increases or decreases due to vibration control of the air-fuel ratio. This fluctuation in engine torque may become large enough to be felt by the vehicle occupants, including the driver, and there is a concern that this may degrade the vehicle's noise and vibration (NV) performance or drivability.

以上の問題に初めて着目してなされた本発明は、空燃比の加振制御に伴う悪影響を最小限に抑えることを所期の目的としている。 The present invention, which was developed for the first time with an eye on the above problems, aims to minimize the adverse effects of vibration control of the air-fuel ratio.

本発明では、車両に搭載される内燃機関を制御する制御装置であって、気筒から排出され排気浄化用の触媒に流入するガスの空燃比を強制的に増減させる加振制御を実施する際、気筒における燃焼の機会毎または単位時間あたりの空燃比の変化量を、内燃機関が出力するエンジントルクの変動量が許容範囲に収まると考えられる所要値以下に設定して空燃比を徐変させる内燃機関の制御装置を構成した。 The present invention provides a control device for controlling an internal combustion engine mounted on a vehicle, and when performing vibration control to forcibly increase or decrease the air-fuel ratio of gas discharged from a cylinder and flowing into an exhaust purification catalyst, the control device for the internal combustion engine is configured to gradually change the air-fuel ratio by setting the amount of change in the air-fuel ratio per combustion opportunity in the cylinder or per unit time to a required value or less that is considered to keep the amount of fluctuation in the engine torque output by the internal combustion engine within an acceptable range.

加振制御において空燃比を緩やかに増減させることの副効用として、内燃機関の冷間始動直後等の触媒の早期の昇温を促すことも可能になる。 As a side effect of gradually increasing and decreasing the air-fuel ratio in vibration control, it is also possible to promote early heating of the catalyst, for example, immediately after a cold start of the internal combustion engine.

前記加振制御を実施する際、空燃比をリッチに変化させる期間には気筒における混合気への点火タイミングをそれ以外の期間に比して遅角補正することも好ましい。さすれば、空燃比のリッチ化によるエンジントルクの不必要な増大を抑制してエンジントルクの変動をより縮小することができる。その上で、前記加振制御において、空燃比をリッチ側の下限まで低減させる期間における空燃比の燃焼機会毎または単位時間あたりの変化量の絶対値を、空燃比をリーン側の上限まで増加させる期間における空燃比の燃焼機会毎または単位時間あたりの変化量の絶対値よりも大きくとるようにしてもよい。 When performing the vibration control, it is also preferable to retard the ignition timing of the mixture in the cylinder during the period in which the air-fuel ratio is changed to the rich side, compared to the other periods. In this way, it is possible to suppress unnecessary increases in engine torque due to the enrichment of the air-fuel ratio, and to further reduce the fluctuations in engine torque. In addition, in the vibration control, the absolute value of the amount of change in the air-fuel ratio per combustion opportunity or per unit time during the period in which the air-fuel ratio is reduced to the lower limit on the rich side may be set to be greater than the absolute value of the amount of change in the air-fuel ratio per combustion opportunity or per unit time during the period in which the air-fuel ratio is increased to the upper limit on the lean side.

本発明によれば、空燃比の加振制御に伴う悪影響を最小限に抑えることができる。 The present invention makes it possible to minimize the adverse effects of vibration control of the air-fuel ratio.

本発明の一実施形態における車両用内燃機関及び制御装置の概略構成を示す図。1 is a diagram showing a schematic configuration of a vehicle internal combustion engine and a control device according to an embodiment of the present invention; 同実施形態の制御装置がプログラムに従い実行する処理の手順例を示すフロー図。FIG. 4 is a flowchart showing an example of a procedure of a process executed by the control device according to the embodiment in accordance with a program. 同実施形態の制御装置による制御の内容を説明するタイミング図。FIG. 4 is a timing chart illustrating the contents of control performed by the control device according to the embodiment. 同実施形態の制御装置による制御の内容を説明するタイミング図。FIG. 4 is a timing chart illustrating the contents of control performed by the control device according to the embodiment.

本発明の一実施形態を、図面を参照して説明する。図1に、本実施形態における車両用内燃機関の概要を示す。本実施形態における内燃機関は、火花点火式の4ストロークエンジンであり、複数の気筒1(図1には、そのうち一つを図示している)を具備している。各気筒1の吸気ポート近傍には、燃料を噴射するインジェクタ11を設けている。また、各気筒1の燃焼室の天井部に、点火プラグ12を取り付けてある。点火プラグ12は、点火コイルにて発生した誘導電圧の印加を受けて、中心電極と接地電極との間で火花放電を惹起するものである。 One embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an overview of an internal combustion engine for a vehicle in this embodiment. The internal combustion engine in this embodiment is a spark-ignition four-stroke engine, and is equipped with multiple cylinders 1 (one of which is shown in FIG. 1). An injector 11 for injecting fuel is provided near the intake port of each cylinder 1. In addition, an ignition plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The ignition plug 12 generates a spark discharge between a center electrode and a ground electrode when an induced voltage generated by an ignition coil is applied to the ignition plug 12.

吸気を供給するための吸気通路3は、外部から空気を取り入れて各気筒1の吸気ポートへと導く。吸気通路3上には、エアクリーナ31、電子スロットルバルブ32、サージタンク33、吸気マニホルド34を、上流からこの順序に配置している。 The intake passage 3 for supplying intake air takes in air from the outside and directs it to the intake port of each cylinder 1. An air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from upstream on the intake passage 3.

排気を排出するための排気通路4は、気筒1内で燃料を燃焼させた結果発生した排気ガスを各気筒1の排気ポートから外部へと導く。この排気通路4上には、排気マニホルド42及び排気浄化用の三元触媒41を配置している。 The exhaust passage 4 for discharging exhaust gases guides exhaust gases generated as a result of burning fuel in the cylinders 1 from the exhaust ports of each cylinder 1 to the outside. An exhaust manifold 42 and a three-way catalyst 41 for purifying exhaust gases are arranged on this exhaust passage 4.

排気通路4における触媒41の上流及び下流には、排気通路4を流通するガスの空燃比を検出するための空燃比センサ43、44を設置する。空燃比センサ43、44はそれぞれ、排気ガスの空燃比に対して非線形な出力特性を有するO2センサであってもよく、排気ガスの空燃比に比例した出力特性を有するリニアA/Fセンサであってもよい。 Air-fuel ratio sensors 43, 44 for detecting the air-fuel ratio of the gas flowing through the exhaust passage 4 are installed upstream and downstream of the catalyst 41 in the exhaust passage 4. The air-fuel ratio sensors 43, 44 may each be an O2 sensor having a nonlinear output characteristic with respect to the air-fuel ratio of the exhaust gas, or a linear A/F sensor having an output characteristic proportional to the air-fuel ratio of the exhaust gas.

排気ガス再循環(Exhaust Gas Recirculation)装置2は、排気通路4と吸気通路3とを連通する外部EGR通路21と、EGR通路21上に設けたEGRクーラ22と、EGR通路21を開閉し当該EGR通路21を流れるEGRガスの流量を制御するEGRバルブ23とを要素とする。EGR通路21の入口は、排気通路4における触媒41の下流の所定箇所に接続している。EGR通路21の出口は、吸気通路3におけるスロットルバルブ32の下流の所定箇所(特に、サージタンク33または吸気マニホルド34)に接続している。 The exhaust gas recirculation device 2 includes an external EGR passage 21 that connects the exhaust passage 4 and the intake passage 3, an EGR cooler 22 provided on the EGR passage 21, and an EGR valve 23 that opens and closes the EGR passage 21 to control the flow rate of EGR gas flowing through the EGR passage 21. The inlet of the EGR passage 21 is connected to a predetermined location downstream of the catalyst 41 in the exhaust passage 4. The outlet of the EGR passage 21 is connected to a predetermined location downstream of the throttle valve 32 in the intake passage 3 (in particular, the surge tank 33 or the intake manifold 34).

本実施形態の内燃機関の制御装置たるECU0は、プロセッサ、メモリ、入力インタフェース、出力インタフェース等を有したマイクロコンピュータシステムである。ECU0は、複数基のECUまたはコントローラがCAN(Controller Area Network)等の電気通信回線を介して相互に通信可能に接続されてなるものであることがある。 The ECU0, which is the control device for the internal combustion engine in this embodiment, is a microcomputer system having a processor, memory, an input interface, an output interface, etc. The ECU0 may be configured by connecting multiple ECUs or controllers so that they can communicate with each other via an electrical communication line such as a CAN (Controller Area Network).

ECU0の入力インタフェースには、車両の実車速を検出する車速センサから出力される車速信号a、内燃機関のクランクシャフトの回転角度及びエンジン回転数を検出するクランク角センサから出力されるクランク角信号b、アクセルペダルの踏込量またはスロットルバルブ32の開度をアクセル開度(いわば、内燃機関に要求されるエンジン負荷率またはエンジントルク)として検出するセンサから出力されるアクセル開度信号c、吸気通路3(特に、サージタンク33または吸気マニホルド34)内の吸気温及び吸気圧を検出する温度・圧力センサから出力される吸気温・吸気圧信号d、内燃機関の冷却水温を検出する水温センサから出力される冷却水温信号e、触媒41の上流側における排気ガスの空燃比を検出する空燃比センサ43から出力される信号f、触媒41の下流側における排気ガスの空燃比を検出する空燃比センサ44から出力される信号g、大気圧を検出する大気圧センサから出力される大気圧信号h等が入力される。 The input interface of the ECU0 receives inputs such as a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal b output from a crank angle sensor that detects the rotation angle of the crankshaft of the internal combustion engine and the engine speed, an accelerator opening signal c output from a sensor that detects the accelerator pedal depression amount or the opening of the throttle valve 32 as the accelerator opening (in other words, the engine load rate or engine torque required for the internal combustion engine), an intake air temperature/intake pressure signal d output from a temperature/pressure sensor that detects the intake air temperature and intake pressure in the intake passage 3 (particularly the surge tank 33 or the intake manifold 34), a cooling water temperature signal e output from a water temperature sensor that detects the cooling water temperature of the internal combustion engine, a signal f output from an air-fuel ratio sensor 43 that detects the air-fuel ratio of the exhaust gas upstream of the catalyst 41, a signal g output from an air-fuel ratio sensor 44 that detects the air-fuel ratio of the exhaust gas downstream of the catalyst 41, and an atmospheric pressure signal h output from an atmospheric pressure sensor that detects the atmospheric pressure.

ECU0の出力インタフェースからは、点火プラグ12のイグナイタ13に対して点火信号i、インジェクタ11に対して燃料噴射信号j、スロットルバルブ32に対して開度操作信号k、EGRバルブ23に対して開度操作信号l等を出力する。 The output interface of ECU0 outputs an ignition signal i to the igniter 13 of the spark plug 12, a fuel injection signal j to the injector 11, an opening operation signal k to the throttle valve 32, an opening operation signal l to the EGR valve 23, etc.

ECU0のプロセッサは、予めメモリに格納されているプログラムを解釈、実行し、運転パラメータを演算して内燃機関の運転を制御する。ECU0は、内燃機関の運転制御に必要な各種情報a、b、c、d、e、f、g、hを入力インタフェースを介して取得し、エンジン回転数を知得するとともに気筒1に吸入される空気(新気)量を推算する。そして、それらエンジン回転数及び吸入空気量等に基づき、要求燃料噴射量、燃料噴射タイミング(一度の燃焼に対する燃料噴射の回数を含む)、燃料噴射圧、要求EGR率(または、EGRガス量)、点火タイミング(一度の燃焼に対する火花点火の回数を含む)等といった各種運転パラメータを決定する。ECU0は、運転パラメータに対応した各種制御信号i、j、k、lを出力インタフェースを介して印加する。 The processor of ECU0 interprets and executes programs stored in memory in advance, and calculates operating parameters to control the operation of the internal combustion engine. ECU0 acquires various pieces of information a, b, c, d, e, f, g, and h necessary for controlling the operation of the internal combustion engine via the input interface, and determines the engine speed and estimates the amount of air (fresh air) drawn into cylinder 1. Then, based on the engine speed and intake air volume, etc., it determines various operating parameters such as the required fuel injection amount, fuel injection timing (including the number of fuel injections per combustion), fuel injection pressure, required EGR rate (or EGR gas amount), ignition timing (including the number of spark ignitions per combustion), etc. ECU0 applies various control signals i, j, k, and l corresponding to the operating parameters via the output interface.

燃料噴射量を決定するにあたり、ECU0は、まず、気筒1に吸入される空気の量を求め、その吸入空気量に対して目標空燃比を実現できような燃料噴射量の基本量TPを決定する。吸入空気量は、エンジン回転数及び吸気圧を基に推算する。必要であれば、その推算値に、吸気温や大気圧等に応じた補正を加えることができる。なお、吸気通路3にエアフローメータが設置されているならば、エアフローメータを介して吸入空気量を直接計測することが可能である。 In determining the fuel injection amount, the ECU 0 first obtains the amount of air taken into the cylinder 1, and then determines a basic amount TP of fuel injection amount that can realize a target air-fuel ratio for that amount of intake air. The amount of intake air is estimated based on the engine speed and intake pressure. If necessary, the estimated value can be corrected according to the intake temperature, atmospheric pressure, etc. If an airflow meter is installed in the intake passage 3, it is possible to directly measure the amount of intake air via the airflow meter.

次いで、この基本噴射量TPを、触媒41に流入するガスの実測空燃比と目標空燃比との偏差に応じたフィードバック補正係数FAFや、環境条件その他に応じて定まる各種補正係数Kにより補正する。補正係数FAF、Kはそれぞれ、1を中心に増減する正数である。さらに、インジェクタ11を開弁しても燃料が噴出しない無効噴射時間TAUVを加味して、最終的な燃料噴射時間T、即ちインジェクタ11を開弁するべくこれに通電する時間を算定する。燃料噴射時間Tは、
T=TP×FAF×K+TAUV
となる。ECU0は、燃料噴射時間Tだけインジェクタ11に対して信号jを入力し、インジェクタ11を開弁して燃料を噴射させる。
Next, this basic injection amount TP is corrected by a feedback correction coefficient FAF corresponding to the deviation between the measured air-fuel ratio of the gas flowing into the catalyst 41 and the target air-fuel ratio, and various correction coefficients K determined according to environmental conditions and the like. The correction coefficients FAF and K are each a positive number that increases or decreases from 1. Furthermore, the final fuel injection time T, i.e., the time for which current is supplied to the injector 11 to open it, is calculated taking into account the invalid injection time TAUV during which no fuel is injected even when the injector 11 is opened. The fuel injection time T is calculated as follows:
T = TP x FAF x K + TAUV
The ECU 0 inputs a signal j to the injector 11 for the fuel injection time T, and opens the valve of the injector 11 to inject fuel.

ECU0は、原則として、理論空燃比またはその近傍の空燃比を目標空燃比とし、そのような空燃比を達成できるように燃料噴射量を調整する。燃料としてガソリンを使用する内燃機関であれば、平常の目標空燃比は14.6ないしその近傍の値となる。 In principle, ECU0 sets the target air-fuel ratio to the theoretical air-fuel ratio or an air-fuel ratio close to that, and adjusts the fuel injection amount so that such an air-fuel ratio can be achieved. In an internal combustion engine that uses gasoline as fuel, the normal target air-fuel ratio is 14.6 or a value close to that.

しかしながら、三元触媒41は、これに流入するガスの空燃比がある程度以上増減変動していないと、却って有害物質の浄化能率が低下してしまう。そこで、図2に示すように、本実施形態のECU0は、空燃比を変動させるべき状況が訪れると(ステップS1)、一時的に触媒41に流入するガスの空燃比を強制的に増減させる加振制御を実施する(ステップS2)。 However, if the air-fuel ratio of the gas flowing into the three-way catalyst 41 does not fluctuate by more than a certain amount, the purification efficiency of harmful substances will actually decrease. Therefore, as shown in FIG. 2, when a situation arises in which it is necessary to fluctuate the air-fuel ratio (step S1), the ECU 0 of this embodiment performs vibration control to temporarily forcibly increase or decrease the air-fuel ratio of the gas flowing into the catalyst 41 (step S2).

ステップS1にいう、空燃比を変動させるべき状況とは、典型的には、車速またはエンジン回転数の単位時間あたりの変化量の絶対値が閾値よりも小さく、かつアクセル開度の単位時間あたりの変化量の絶対値が閾値よりも小さいような定常走行が一定時間以上継続しているときである。このような状況下では、ガスの空燃比が理論空燃比近傍に収束している状態が続き、その帰結として有害物質の排出量が増加することがあり得る。 The situation in step S1 where the air-fuel ratio should be changed typically occurs when steady driving continues for a certain period of time or more, in which the absolute value of the amount of change per unit time in the vehicle speed or engine speed is smaller than a threshold value, and the absolute value of the amount of change per unit time in the accelerator opening is smaller than a threshold value. In such a situation, the gas air-fuel ratio continues to converge near the theoretical air-fuel ratio, which can result in an increase in the amount of harmful substance emissions.

ステップS2の加振制御では、ガスの空燃比を、理論空燃比を跨ぐようにリッチとリーンとの間で振動させる。燃料としてガソリンを使用する内燃機関であれば、例えば、空燃比を、理論空燃比よりもリッチな13.3程度まで低減させる期間と、理論空燃比よりもリーンな16程度まで増加させる期間とを設ける。 In the vibration control of step S2, the air-fuel ratio of the gas is oscillated between rich and lean so as to straddle the theoretical air-fuel ratio. In the case of an internal combustion engine that uses gasoline as fuel, for example, a period is provided in which the air-fuel ratio is reduced to about 13.3, which is richer than the theoretical air-fuel ratio, and a period is provided in which the air-fuel ratio is increased to about 16, which is leaner than the theoretical air-fuel ratio.

その上で、図3または図4に示すように、本実施形態では、空燃比の加振制御において、各気筒1における燃焼の機会(即ち、サイクル)毎または単位時間あたりの空燃比の変化量を、エンジントルクの変動量が車両のNV性能及びドライバビリティを低下させないような許容範囲に収まると考えられる所要値以下に設定し、空燃比を急変させず徐変させるようにする。このとき、燃料噴射量Tの燃焼機会毎または単位時間あたりの変化量も、エンジントルクの変動量が許容範囲に収まる所要値以下となる。 In addition, as shown in FIG. 3 or FIG. 4, in this embodiment, in the air-fuel ratio oscillation control, the amount of change in the air-fuel ratio for each combustion opportunity (i.e., cycle) or per unit time in each cylinder 1 is set to a required value or less that is considered to be within an acceptable range in which the amount of engine torque fluctuation does not degrade the vehicle's NV performance and drivability, and the air-fuel ratio is changed gradually without being changed suddenly. At this time, the amount of change in the fuel injection amount T for each combustion opportunity or per unit time is also set to a required value or less that is within an acceptable range in which the amount of engine torque fluctuation falls.

空燃比がリッチ側の下限(例えば、13.3)まで低減する期間における空燃比の燃焼機会毎または単位時間あたりの変化量ΔR、空燃比がリーン側の上限(例えば、16)まで増加する期間における空燃比の燃焼機会毎または単位時間あたりの変化量ΔLはそれぞれ、そのときの車速、エンジン回転数、エンジン負荷率等のうちの何れか一つまたは複数に応じて可変に調整してよい。 The amount of change ΔR in the air-fuel ratio per combustion opportunity or per unit time during the period when the air-fuel ratio decreases to the lower limit on the rich side (e.g., 13.3), and the amount of change ΔL in the air-fuel ratio per combustion opportunity or per unit time during the period when the air-fuel ratio increases to the upper limit on the lean side (e.g., 16) may each be variably adjusted according to one or more of the vehicle speed, engine speed, engine load factor, etc. at that time.

前者の変化量ΔRの絶対値の大きさと、後者の変化量ΔLの絶対値の大きさとが、均等であるとは限られない。図4に示す例は、空燃比の加振制御中に、各気筒1での混合気への火花点火のタイミングに補正を加えるものである。内燃機関の熱機械変換効率を最大化するべく、通常、点火タイミングは、MBT(Minimum advance for Best Torque)とし、またはノッキング等の異常燃焼を惹起しない限りにおいて可及的にMBTに近づけている。図4に示す例では、空燃比をリッチに変化させる期間において、点火タイミングをそのような平常のタイミングよりも遅角させ、空燃比のリッチ化によるエンジントルクの増大を相殺している。その分、空燃比をリッチに変化させる期間における空燃比の変化量ΔRの絶対値を、空燃比をリーンに変化させる期間における空燃比の変化量ΔLの絶対値よりも大きくとることが許される。換言すれば、空燃比をリッチに変化させる期間では、より速やかに空燃比を変化させてよい。 The magnitude of the absolute value of the former change amount ΔR and the magnitude of the absolute value of the latter change amount ΔL are not necessarily equal. The example shown in FIG. 4 is a correction to the timing of spark ignition to the mixture in each cylinder 1 during the vibration control of the air-fuel ratio. In order to maximize the thermomechanical conversion efficiency of the internal combustion engine, the ignition timing is usually set to MBT (Minimum advance for Best Torque), or is as close to MBT as possible as long as it does not cause abnormal combustion such as knocking. In the example shown in FIG. 4, during the period in which the air-fuel ratio is changed to rich, the ignition timing is retarded from such normal timing to offset the increase in engine torque due to the enrichment of the air-fuel ratio. Accordingly, the absolute value of the change amount ΔR of the air-fuel ratio during the period in which the air-fuel ratio is changed to rich is allowed to be larger than the absolute value of the change amount ΔL of the air-fuel ratio during the period in which the air-fuel ratio is changed to lean. In other words, during the period when the air-fuel ratio is changed to a richer state, the air-fuel ratio may be changed more quickly.

本実施形態では、車両に搭載される内燃機関を制御する制御装置0であって、気筒1から排出され排気浄化用の触媒41に流入するガスの空燃比を強制的に増減させる加振制御を実施する際、気筒1における燃焼の機会毎または単位時間あたりの空燃比の変化量を、内燃機関が出力するエンジントルクの変動量が許容範囲に収まると考えられる所要値以下に設定して空燃比を徐変させる内燃機関の制御装置0を構成した。本実施形態によれば、加振制御に伴うエンジントルクの変動が十分に緩やかとなり、車両のNV性能やドライバビリティを高く維持することが可能となる。 In this embodiment, the control device 0 controls an internal combustion engine mounted on a vehicle, and when performing vibration control to forcibly increase or decrease the air-fuel ratio of gas discharged from cylinder 1 and flowing into an exhaust purification catalyst 41, the control device 0 for the internal combustion engine is configured to gradually change the air-fuel ratio by setting the amount of change in the air-fuel ratio per combustion opportunity or per unit time in cylinder 1 to a required value or less that is considered to keep the amount of change in the engine torque output by the internal combustion engine within an acceptable range. According to this embodiment, the fluctuation in engine torque caused by the vibration control becomes sufficiently gentle, making it possible to maintain high NV performance and drivability of the vehicle.

また、内燃機関の冷間始動直後等の触媒41の温度が低温である時期に、空燃比の加振制御を実施するとともに、上述の通り空燃比を徐変させることで、触媒41を早期に昇温させてその活性化を促すこともできる。触媒41が早期に活性化すれば、その分だけ有害物質の排出量が削減されることになる。 In addition, when the temperature of the catalyst 41 is low, such as immediately after a cold start of the internal combustion engine, by implementing vibration control of the air-fuel ratio and gradually changing the air-fuel ratio as described above, it is possible to heat the catalyst 41 early and promote its activation. If the catalyst 41 is activated early, the amount of harmful substances emitted will be reduced accordingly.

加えて、前記加振制御を実施する際、空燃比をリッチに変化させる期間には気筒1における混合気への点火タイミングをそれ以外の期間に比して遅角補正することも考えられる。さすれば、空燃比のリッチ化によるエンジントルクの不必要な増大を抑制してエンジントルクの変動をより縮小できる。 In addition, when implementing the vibration control, it is also possible to retard the ignition timing of the mixture in cylinder 1 during the period in which the air-fuel ratio is changed to rich, compared to other periods. This can suppress unnecessary increases in engine torque due to the enrichment of the air-fuel ratio, and further reduce fluctuations in engine torque.

なお、本発明は以上に詳述した実施形態に限られるものではない。例えば、ステップS2にて、空燃比の加振制御は、内燃機関が具備する複数の気筒1の全てにおいて一斉に実施してもよいが、一部の気筒1に限り加振制御を実施し、残りの気筒1では依然として空燃比を理論空燃比またはその近傍に維持することとしてもよい。 The present invention is not limited to the embodiment described above in detail. For example, in step S2, the vibration control of the air-fuel ratio may be performed simultaneously for all of the multiple cylinders 1 of the internal combustion engine, or the vibration control may be performed only for some of the cylinders 1, and the air-fuel ratio of the remaining cylinders 1 may still be maintained at or near the theoretical air-fuel ratio.

その他、各部の具体的な構成や処理の手順等は、本発明の趣旨を逸脱しない範囲で種々変形が可能である。 In addition, the specific configuration of each part and the processing procedures can be modified in various ways without departing from the spirit of the present invention.

本発明は、車両に搭載される内燃機関の制御に適用することができる。 The present invention can be applied to the control of an internal combustion engine mounted on a vehicle.

0…制御装置(ECU)
1…気筒
11…インジェクタ
12…点火プラグ
3…吸気通路
4…排気通路
41…触媒
43、44…空燃比センサ
a…車速信号
b…クランク角信号
c…アクセル開度信号
f、g…空燃比信号
i…点火信号
j…燃料噴射信号
0...Control unit (ECU)
REFERENCE SIGNS LIST 1 cylinder 11 injector 12 spark plug 3 intake passage 4 exhaust passage 41 catalyst 43, 44 air-fuel ratio sensor a vehicle speed signal b crank angle signal c accelerator opening signal f, g air-fuel ratio signal i ignition signal j fuel injection signal

Claims (1)

車両に搭載される内燃機関を制御する制御装置であって、
気筒から排出され排気浄化用の触媒に流入するガスの空燃比を強制的に増減させる加振制御を実施する際、気筒における燃焼の機会毎または単位時間あたりの空燃比の変化量を、内燃機関が出力するエンジントルクの変動量が許容範囲に収まると考えられる所要値以下に設定して空燃比を徐変させるものであり、
前記加振制御を実施する際、空燃比をリッチに変化させる期間には気筒における混合気への点火タイミングをそれ以外の期間に比して遅角補正することとし、
前記加振制御において、空燃比をリッチ側の下限まで低減させる期間における空燃比の燃焼機会毎または単位時間あたりの変化量の絶対値を、空燃比をリーン側の上限まで増加させる期間における空燃比の燃焼機会毎または単位時間あたりの変化量の絶対値よりも大きくとる内燃機関の制御装置。
A control device for controlling an internal combustion engine mounted on a vehicle,
When performing vibration control to forcibly increase or decrease the air-fuel ratio of gas discharged from a cylinder and flowing into an exhaust gas purification catalyst, the amount of change in the air-fuel ratio for each combustion opportunity in the cylinder or per unit time is set to a required value or less that is considered to cause the amount of fluctuation in the engine torque output by the internal combustion engine to fall within an acceptable range , thereby gradually changing the air-fuel ratio,
When the vibration control is performed, the ignition timing of the mixture in the cylinder is retarded during a period in which the air-fuel ratio is changed to a richer value compared to other periods,
A control device for an internal combustion engine, in which, in the vibration control, an absolute value of an amount of change in the air-fuel ratio per combustion opportunity or per unit time during a period in which the air-fuel ratio is reduced to a lower limit on the rich side is set to be larger than an absolute value of an amount of change in the air-fuel ratio per combustion opportunity or per unit time during a period in which the air-fuel ratio is increased to an upper limit on the lean side.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005171979A (en) 2003-11-21 2005-06-30 Denso Corp Controller for internal combustion engine
JP2008274823A (en) 2007-04-27 2008-11-13 Toyota Motor Corp Oxygen sensor failure diagnosis device for internal combustion engine
WO2012090267A1 (en) 2010-12-27 2012-07-05 トヨタ自動車株式会社 Internal combustion engine control apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005171979A (en) 2003-11-21 2005-06-30 Denso Corp Controller for internal combustion engine
JP2008274823A (en) 2007-04-27 2008-11-13 Toyota Motor Corp Oxygen sensor failure diagnosis device for internal combustion engine
WO2012090267A1 (en) 2010-12-27 2012-07-05 トヨタ自動車株式会社 Internal combustion engine control apparatus

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