JPH04358735A - Air-fuel ratio controller of internal combustion engine - Google Patents
Air-fuel ratio controller of internal combustion engineInfo
- Publication number
- JPH04358735A JPH04358735A JP21879991A JP21879991A JPH04358735A JP H04358735 A JPH04358735 A JP H04358735A JP 21879991 A JP21879991 A JP 21879991A JP 21879991 A JP21879991 A JP 21879991A JP H04358735 A JPH04358735 A JP H04358735A
- Authority
- JP
- Japan
- Prior art keywords
- fuel ratio
- air
- assumption
- cylinder pressure
- rich
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000000446 fuel Substances 0.000 title claims abstract description 123
- 238000002485 combustion reaction Methods 0.000 title claims abstract description 18
- 238000001514 detection method Methods 0.000 claims abstract description 26
- 230000008859 change Effects 0.000 claims description 8
- 230000004044 response Effects 0.000 abstract description 11
- 238000000034 method Methods 0.000 description 15
- 230000008569 process Effects 0.000 description 14
- 238000002347 injection Methods 0.000 description 11
- 239000007924 injection Substances 0.000 description 11
- 238000010586 diagram Methods 0.000 description 4
- 230000001133 acceleration Effects 0.000 description 3
- 230000001052 transient effect Effects 0.000 description 3
- 239000000498 cooling water Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
Landscapes
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
Abstract
Description
【０００１】0001
【産業上の利用分野】本発明は、内燃機関の空燃比制御
装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-fuel ratio control device for an internal combustion engine.
【０００２】0002
【従来の技術】従来の内燃機関の空燃比制御装置として
は例えば図６ （Ａ） 〜 （Ｃ） に示すような、各
種の吸入空気流量検出手段を用いて吸入空気流量を測定
し、これに基づいて燃料供給量を決定して空燃比制御を
行うようにしたものが一般的である。因に、図６ （Ａ
） は吸気圧力に感応して回転するベーンの回転量をポ
テンショメータで検出して吸入空気流量を検出するベー
ン式のもの、同図 （Ｂ） は熱線抵抗の吸気流量に応
じた抵抗値変化に基づいてブリッヂ回路への電流を制御
し、該制御電流値を吸入空気流量として検出するホット
ワイヤ式のもの、同図 （Ｃ） はプローブ下流後の渦
量を測定して吸入空気流量を検出するカルマン渦式のも
のを示してある （昭和５５年１０月１５日株式会社山
海堂発行，「自動車工学全書第１０巻電装品，車体装備
品，エンジン部品」第２６３頁等参照） 。BACKGROUND OF THE INVENTION Conventional air-fuel ratio control devices for internal combustion engines measure the intake air flow rate using various intake air flow rate detection means, such as those shown in FIGS. Generally, the fuel supply amount is determined based on the air-fuel ratio and the air-fuel ratio is controlled. Incidentally, Figure 6 (A
) is a vane type that detects the intake air flow rate by detecting the amount of rotation of a vane that rotates in response to intake pressure using a potentiometer, and Figure (B) is a vane type that detects the intake air flow rate by detecting the amount of rotation of a vane that rotates in response to intake pressure. (C) is a hot wire type that controls the current to the bridge circuit and detects the control current value as the intake air flow rate. Figure (C) is a Kalman type that measures the amount of vortex downstream of the probe to detect the intake air flow rate. The vortex type is shown (see "Automotive Engineering Complete Book Vol. 10, Electrical Components, Body Equipment, Engine Parts", page 263, published by Sankaido Co., Ltd., October 15, 1980).
【０００３】0003
【発明が解決しようとする課題】しかしながら、このよ
うに吸入空気流量を検出して空燃比制御を行うものにあ
っては、上記の吸入空気流量検出手段は、大気圧や湿度
、温度の影響を受けて検出精度が低下したり、過渡状態
においては応答遅れを生じたり、あるいは何らかの影響
で故障したりすることが考えられる。このような場合、
機関は正確な空燃比制御を実施できなくなったり、最悪
の場合、運転を停止してしまうおそれがある。[Problem to be Solved by the Invention] However, in such a device that detects the intake air flow rate to control the air-fuel ratio, the above-mentioned intake air flow rate detection means is not sensitive to the effects of atmospheric pressure, humidity, and temperature. As a result, detection accuracy may decrease, response may be delayed in transient conditions, or failure may occur due to some influence. In such a case,
The engine may not be able to perform accurate air-fuel ratio control, or in the worst case, may stop operating.
【０００４】本発明は、このような従来の問題点に着目
してなされたもので、筒内圧を検出して推定される空燃
比状態に応じて燃料供給量を制御し、かつ、制御結果に
応じて空燃比状態の推定を確かなものとして空燃比を目
標値に近づけるように修正制御するようにした内燃機関
の空燃比制御装置を提供することを目的とする。The present invention has been made in view of these conventional problems, and it controls the fuel supply amount according to the air-fuel ratio state estimated by detecting the cylinder pressure, and also controls the fuel supply amount based on the control result. It is an object of the present invention to provide an air-fuel ratio control device for an internal combustion engine that can accurately estimate the air-fuel ratio state and perform corrective control to bring the air-fuel ratio closer to a target value.
【０００５】[0005]
【課題を解決するための手段】このため本発明に係る内
燃機関の空燃比制御装置は図１に示すように、機関の筒
内圧を検出する筒内圧検出手段と、検出された筒内圧の
燃焼行程毎のピーク値と該ピーク値を与えるクランク角
度とを検出する筒内圧ピーク値・クランク角度検出手段
と、前記検出された筒内圧ピーク値とクランク角度とに
基づいて現在の空燃比の目標空燃比からのずれ量を推定
する空燃比ずれ量推定手段と、前記推定された空燃比の
ずれ量が目標空燃比に対してリッチ側であるかリーン側
であるかを仮定するリッチ・リーン仮定手段と、前記推
定された空燃比のずれ量とそのリッチ側又はリーン側の
仮定により空燃比を目標空燃比に近づけるべく燃料供給
量を設定する燃料供給量設定手段と、前記推定された空
燃比のずれ量の変化状態に応じてリッチ・リーンの仮定
が正しいか否かを判定する仮定正誤判定手段と、前記判
定手段による判定結果に応じてリッチ・リーン仮定手段
による仮定を修正する仮定修正手段とを備えて構成した
。[Means for Solving the Problems] Therefore, the air-fuel ratio control device for an internal combustion engine according to the present invention, as shown in FIG. a cylinder pressure peak value/crank angle detection means for detecting a peak value for each stroke and a crank angle that provides the peak value; air-fuel ratio deviation amount estimating means for estimating the amount of deviation from the fuel ratio; and rich/lean assumption means for assuming whether the estimated deviation amount of the air-fuel ratio is on the rich side or lean side with respect to the target air-fuel ratio. and a fuel supply amount setting means for setting a fuel supply amount to bring the air-fuel ratio closer to the target air-fuel ratio based on the estimated deviation amount of the air-fuel ratio and its rich side or lean side assumption; Assumption correctness determining means for determining whether the rich/lean assumption is correct or not according to a change state of the amount of deviation; and assumption correcting means for modifying the assumption by the rich/lean assuming means in accordance with a determination result by the determining means. It was configured with
【０００６】[0006]
【作用】筒内圧検出手段で検出された筒内圧の燃焼行程
毎のピーク値と該ピーク値を与えるクランク角度とが筒
内圧ピーク値・クランク角度検出手段により検出される
。空燃比ずれ量推定手段は、前記検出された筒内圧のピ
ーク値とクランク角度とに基づいて現在の空燃比の目標
空燃比からのずれ量を推定し、リッチ・リーン仮定手段
は前記ずれ量が目標空燃比に対してリッチ側にずれてい
るかリーン側にずれているかを仮定する。[Operation] The peak value of the cylinder pressure detected by the cylinder pressure detection means for each combustion stroke and the crank angle giving the peak value are detected by the cylinder pressure peak value/crank angle detection means. The air-fuel ratio deviation amount estimation means estimates the deviation amount of the current air-fuel ratio from the target air-fuel ratio based on the detected peak value of the in-cylinder pressure and the crank angle, and the rich/lean assumption means estimates the deviation amount of the current air-fuel ratio from the target air-fuel ratio based on the detected peak value of the in-cylinder pressure and the crank angle. Assume whether the target air-fuel ratio is deviated to the rich side or lean side.
【０００７】燃料供給量設定手段は現状空燃比の目標空
燃比に対するずれ量とリッチ・リーンの仮定とに基づい
て空燃比を目標空燃比に近づけるべく燃料供給量を設定
する。仮定正誤判定手段は、空燃比のずれ量の変化状態
に基づいてリッチ・リーンの仮定が正しいか否かを判定
し、該判定結果に基づいて仮定修正手段がリッチ・リー
ンの仮定を修正する。The fuel supply amount setting means sets the fuel supply amount to bring the air-fuel ratio closer to the target air-fuel ratio based on the deviation amount of the current air-fuel ratio from the target air-fuel ratio and the rich/lean assumption. The assumption correctness determining means determines whether the rich/lean assumption is correct based on the state of change in the air-fuel ratio deviation amount, and the assumption correcting means corrects the rich/lean assumption based on the determination result.
【０００８】このようにしてリッチ・リーンの仮定が正
しい方向に修正されることにより空燃比を正しく目標空
燃比に近づける制御を行える。[0008] In this way, the rich/lean assumption is corrected in the correct direction, thereby allowing control to accurately bring the air-fuel ratio close to the target air-fuel ratio.
【０００９】[0009]
【実施例】以下に本発明の実施例を図に基づいて説明す
る。一実施例の構成を示す図２において、点火栓１のシ
リンダヘッドへの着座部に筒内圧を検出する筒内圧セン
サ （筒内圧検出手段） ２が装着され、該筒内圧セン
サ２からの筒内圧信号はアンプ３を介してＰｍａｘ ・
θＰｍａｘ検出回路４に入力される。Ｐｍａｘ ・θＰ
ｍａｘ検出回路４は筒内圧信号の他クランク角センサ５
からのクランク角信号も入力し、前記筒内圧センサ２が
装着された気筒の燃焼行程毎に、筒内圧のピーク値Ｐｍ
ａｘ を検出する。即ち、Ｐｍａｘ ・θＰｍａｘ検出
回路４とクランク角センサ５とで筒内圧ピーク値・クラ
ンク角度検出手段が構成される。[Embodiments] Examples of the present invention will be described below with reference to the drawings. In FIG. 2 showing the configuration of one embodiment, a cylinder pressure sensor (cylinder pressure detection means) 2 for detecting cylinder pressure is attached to the seating part of the spark plug 1 on the cylinder head, and the cylinder pressure sensor 2 detects the cylinder pressure. The signal is passed through amplifier 3 to Pmax・
It is input to the θPmax detection circuit 4. Pmax・θP
The max detection circuit 4 receives the cylinder pressure signal as well as the crank angle sensor 5.
The crank angle signal from the cylinder pressure sensor 2 is also input, and the peak value Pm of the cylinder pressure is determined for each combustion stroke of the cylinder in which the cylinder pressure sensor 2 is installed.
Detect ax. That is, the Pmax/θPmax detection circuit 4 and the crank angle sensor 5 constitute cylinder pressure peak value/crank angle detection means.
【００１０】このようにして検出された燃焼行程毎の筒
内圧ピーク値Ｐｍａｘ とクランク角度θＰｍａｘとは
マイクロコンピュータ６に入力される。マイクロコンピ
ュータ６は、前記各検出値に基づいて現状空燃比の目標
空燃比に対するずれ量を推定すると共に、リッチ・リー
ンのいずれにずれているかを仮定して燃料供給量を設定
することにより空燃比を制御する一方、スロットルセン
サ７によって検出されるスロットル弁開度αや水温セン
サ８によって検出される冷却水温度ＴＷ の状態によっ
て検出される定速，加速，始動等の運転条件毎に空燃比
のずれ量の変化状態に応じてリッチ・リーン仮定の正誤
を判定し、誤っている場合は、仮定を修正する。The in-cylinder pressure peak value Pmax and crank angle θPmax detected in this way for each combustion stroke are input to the microcomputer 6. The microcomputer 6 estimates the amount of deviation of the current air-fuel ratio from the target air-fuel ratio based on the detected values, and sets the fuel supply amount based on whether the current air-fuel ratio is rich or lean. At the same time, the air-fuel ratio is controlled for each operating condition such as constant speed, acceleration, and starting, which is detected by the throttle valve opening α detected by the throttle sensor 7 and the cooling water temperature TW detected by the water temperature sensor 8. The correctness or wrongness of the rich/lean assumption is determined according to the state of change in the amount of deviation, and if it is incorrect, the assumption is corrected.
【００１１】燃料噴射弁９は、機関に設定量の燃料を噴
射供給するものであり、これによって、空燃比が制御さ
れる。次に作用を説明する。まず目標空燃比として理論
空燃比を設定した場合について考える。空燃比に対する
筒内圧波形は図３に示すようになる。即ち、目標空燃比
に対して、リッチ側にずれてもリーン側にずれても筒内
圧は略同様に変化する。したがって空燃比がリッチ側に
ずれているのかリーン側にずれているのかが分かれば、
筒内圧変化のパターンによって空燃比の予測値は決定さ
れる。The fuel injection valve 9 injects and supplies a set amount of fuel to the engine, thereby controlling the air-fuel ratio. Next, the action will be explained. First, consider the case where the stoichiometric air-fuel ratio is set as the target air-fuel ratio. The in-cylinder pressure waveform with respect to the air-fuel ratio is shown in FIG. That is, the cylinder pressure changes in substantially the same way whether the target air-fuel ratio shifts to the rich side or lean side. Therefore, if you can tell whether the air-fuel ratio is shifting toward the rich side or toward the lean side,
The predicted value of the air-fuel ratio is determined by the pattern of changes in cylinder pressure.
【００１２】かかる前提に基づいて前記マイクロコンピ
ュータ６により行われる空燃比制御を図４及び図５に示
したフローチャートに従って説明する。ステップ （図
ではＳと記す。以下同様） １では、吸入空気流量と空
燃比との予め設定した初期値に基づき決定された燃料噴
射量の初期値Ｔ０ に相当する燃料量が燃料噴射弁９か
ら噴射される。Based on this premise, the air-fuel ratio control performed by the microcomputer 6 will be explained with reference to the flowcharts shown in FIGS. 4 and 5. In step 1 (denoted as S in the figure; the same applies hereinafter), the fuel amount corresponding to the initial value T0 of the fuel injection amount determined based on the preset initial values of the intake air flow rate and the air-fuel ratio is supplied from the fuel injection valve 9. Injected.
【００１３】ステップ２では、前記筒内圧センサ２が装
着された気筒 （以下特定気筒という） の燃焼行程が
終了したか否かをクランク角センサ５からの気筒判別信
号によって判定し、燃焼行程終了判定後ステップ３へ進
む。
ステップ３では、前記Ｐｍａｘ ・θＰｍａｘ検出回路
４により検出されている燃焼行程毎の筒内圧のピーク値
Ｐｍａｘ とそのＰｍａｘ 発生時のクランク角度θＰ
ｍａｘとを入力する。In step 2, it is determined whether the combustion stroke of the cylinder in which the cylinder pressure sensor 2 is installed (hereinafter referred to as a specific cylinder) has ended based on the cylinder discrimination signal from the crank angle sensor 5, and the combustion stroke end determination is made. Proceed to step 3. In step 3, the peak value Pmax of the cylinder pressure for each combustion stroke detected by the Pmax/θPmax detection circuit 4 and the crank angle θP at the time of occurrence of the peak value Pmax are determined.
Enter max.
【００１４】次いでステップ４へ進み、ステップ３で入
力されたＰｍａｘ とθＰｍａｘとに基づいて目標空燃
比からのずれ量を推定する。これは具体的には、図３に
示した筒内圧と空燃比との関係から設定したものをマイ
クロコンピュータ６のＲＯＭに記憶した３次元マップか
ら検索すること等によって設定する。ステップ５では、
スロットルセンサ７からの弁開度α信号に基づき単位時
間Δｔ当りの変化量Δαが正の所定値Δα０ を上回る
加速時か否かを判定し、加速と判定されたときはステッ
プ６へ進んで次回 （Δｔ秒後） の燃料噴射量を吸入
空気流量の増量に対して増量補正すべくステップ６へ進
んで空燃比がリーン側へずれていると仮定する。Next, the process proceeds to step 4, in which the amount of deviation from the target air-fuel ratio is estimated based on Pmax and θPmax input in step 3. Specifically, this is set by searching a three-dimensional map stored in the ROM of the microcomputer 6 based on the relationship between the in-cylinder pressure and the air-fuel ratio shown in FIG. In step 5,
Based on the valve opening α signal from the throttle sensor 7, it is determined whether or not the amount of change Δα per unit time Δt exceeds a positive predetermined value Δα0. It is assumed that the process proceeds to step 6 to increase the fuel injection amount (after Δt seconds) in response to the increase in the intake air flow rate, and that the air-fuel ratio has shifted to the lean side.
【００１５】また、ステップ５の判定がＮＯであるとき
はステップ７へ進んで同じく変化量Δαが負の所定値−
Δα０ を下回る減速時か否かを判定し、減速と判定し
たときはステップ８へ進んで次回の燃料噴射量を吸入空
気流量の減量に対して減量補正すべく空燃比がリッチ側
へずれていると仮定する。ステップ７の判定がＮＯであ
る （−Δα０ ≦α≦Δα０ ） 定常状態では、ス
テップ９へ進んで水温センサ８によって検出された冷却
水温度ＴＷ が設定値ＴＷ０ （例えば６０度Ｃ） 以
下の始動，暖機時であるか否かを判定し、ＹＥＳのとき
は、空燃比をリーン化して燃焼温度を高めて暖機を促進
すべくステップ８へ進んで現状の空燃比がリッチ側へず
れていると仮定し、ＮＯである暖機が略完了したときは
、ステップ１０に進み前回 （Δｔ秒前） の仮定と同
一の仮定を維持する。尚、制御開始後第１回目では初期
の仮定 （リッチ又はリーン） がセットされる。If the determination in step 5 is NO, the process proceeds to step 7 where the change amount Δα is also set to a negative predetermined value -
It is determined whether or not the deceleration is below Δα0, and when it is determined that the deceleration is occurring, the process proceeds to step 8 and the air-fuel ratio is shifted to the rich side in order to correct the next fuel injection amount in response to the reduction in the intake air flow rate. Assume that If the determination in step 7 is NO (-Δα0 ≦α≦Δα0), in the steady state, proceed to step 9, and if the cooling water temperature TW detected by the water temperature sensor 8 is lower than the set value TW0 (for example, 60 degrees C), the startup It is determined whether or not it is time to warm up, and if YES, the process proceeds to step 8 to make the air-fuel ratio lean and increase the combustion temperature to promote warm-up, indicating that the current air-fuel ratio has shifted to the rich side. Assuming that, if the warm-up is substantially completed (NO), the process proceeds to step 10, and the same assumption as the previous one (Δt seconds ago) is maintained. Note that the initial assumption (rich or lean) is set for the first time after starting the control.
【００１６】ステップ１１では、前記ステップ４で推定
された空燃比のずれ量とステップ６，８，１０でのずれ
方向の仮定に基づいて目標空燃比に近づけるべく燃料噴
射量を初期値に対して増減補正することによって設定す
る。
次いでステップ１２では、前記設定された燃料噴射量の
燃料が特定気筒に供給されて燃焼を終了したか否かを気
筒判別信号によって判別し、燃焼行程終了後ステップ１
３で新たに検出されたＰｍａｘ ，θＰｍａｘを入力す
る。In step 11, based on the air-fuel ratio deviation amount estimated in step 4 and the assumption of the deviation direction in steps 6, 8, and 10, the fuel injection amount is adjusted from the initial value in order to approach the target air-fuel ratio. Set by correcting increase/decrease. Next, in step 12, it is determined based on the cylinder discrimination signal whether or not the set fuel injection amount of fuel has been supplied to the specific cylinder and combustion has ended, and after the completion of the combustion stroke, step 1 is performed.
Input the newly detected Pmax and θPmax in step 3.
【００１７】ステップ１４では、前記Ｐｍａｘ ，θＰ
ｍａｘに基づいて空燃比からのずれ量を設定する。ステ
ップ１５では、今回ステップ１４で推定された空燃比の
ずれ量と前回の推定されたずれ量とを比較し、ずれ量が
拡大しているか否かによって前回のリッチ・リーンの仮
定の正誤を判定する。In step 14, the Pmax, θP
The amount of deviation from the air-fuel ratio is set based on max. In step 15, the current air-fuel ratio deviation amount estimated in step 14 is compared with the previous estimated deviation amount, and it is determined whether the previous rich-lean assumption is correct or not depending on whether the deviation amount has increased. do.
【００１８】即ち、リッチ・リーンの仮定が正しければ
、それに対して行われる燃料噴射量の増減補正が正しい
方向になされていることにより筒内圧が上昇して空燃比
のずれ量が減少することになるため、ステップ１５で仮
定が正しいと判定される。この場合は、ステップ１６で
誤判定繰り返し回数カウンタを０にリセットした後、ス
テップ５へ戻り、再度運転条件に応じたリッチ・リーン
仮定とステップ１４で推定した空燃比の擦れ量とに基づ
いて燃料噴射量を設定して空燃比制御を行う。In other words, if the rich-lean assumption is correct, the in-cylinder pressure will increase and the air-fuel ratio deviation will decrease because the fuel injection amount is corrected in the correct direction. Therefore, it is determined in step 15 that the assumption is correct. In this case, after resetting the misjudgment repetition counter to 0 in step 16, the process returns to step 5, and the fuel is refueled based on the rich/lean assumption according to the operating conditions and the amount of air-fuel ratio friction estimated in step 14. Sets the injection amount and performs air-fuel ratio control.
【００１９】一方、ステップ１５で空燃比のずれ量が拡
大して仮定が誤っていると判定された時はステップ１７
へ進み、今回の仮定を前回の仮定とは反対の仮定 （リ
ッチのときはリーン、リーンのときはリッチ） に修正
する。次いでステップ１８で誤判繰り返し回数カウンタ
Ｃをカウントアップした後、ステップ１９へ進み前記カ
ウンタのカウント値Ｃが所定値Ｃ０以上あるか否かを判
定して所定値Ｃ０ 未満のときはステップ５へ戻るが、
所定値Ｃ０ 以上のときはステップ２０へ進む。On the other hand, if it is determined in step 15 that the air-fuel ratio deviation has increased and the assumption is incorrect, step 17
Proceed to , and modify the current assumption to be the opposite of the previous assumption (lean when rich, rich when lean). Next, in step 18, after counting up the misjudgment repetition counter C, the process proceeds to step 19, and it is determined whether the count value C of the counter is greater than or equal to a predetermined value C0, and if it is less than the predetermined value C0, the process returns to step 5. ,
If the value is equal to or greater than the predetermined value C0, the process proceeds to step 20.
【００２０】即ち、空燃比がリッチ・リーンを何回も繰
り返さないような比較的安定した状態においては、空燃
比のずれ量とリッチ・リーンの仮定についての修正によ
り空燃比を目標空燃比に収束させることができる。これ
に対し、スロットル弁開度を急激に変化させた急加・減
速時等では空燃比がリッチ・リーンを繰り返すことがあ
り、これに対して空燃比のずれ量とリッチ・リーンの仮
定及び修正により空燃比制御を行っても信頼性が乏しい
ため却って空燃比の変動を大きくしてしまうことがある
。In other words, in a relatively stable state where the air-fuel ratio does not repeat rich-lean cycles many times, the air-fuel ratio can be converged to the target air-fuel ratio by correcting the air-fuel ratio deviation amount and the rich-lean assumption. can be done. On the other hand, during sudden acceleration or deceleration when the throttle valve opening is suddenly changed, the air-fuel ratio may repeatedly cycle between rich and lean. Even if the air-fuel ratio is controlled by this method, the reliability is poor and the air-fuel ratio may actually increase fluctuations.
【００２１】このため、ステップ１９でリッチ・リーン
の仮定の修正が連続して所定回数Ｃ０ 行われたと判定
されたときは、上記のような急加・減運転であると判断
してステップ２０へ進み、予め設定された一定の基準空
燃比に対応して燃料噴射量を設定する。そして前記設定
された燃料噴射量に対して燃焼が終了したことをステッ
プ２１で判定した後、ステップ２２へ進み、スロットル
弁開度の変化量｜Δα｜が所定値Δα１ （＞Δα０
） 以上であるか否かを判定する。Therefore, when it is determined in step 19 that the rich/lean assumptions have been corrected a predetermined number of times C0 consecutively, it is determined that this is sudden acceleration/deceleration operation as described above, and the process proceeds to step 20. Then, the fuel injection amount is set in accordance with a preset constant reference air-fuel ratio. After determining in step 21 that combustion has ended for the set fuel injection amount, the process proceeds to step 22, where the amount of change |Δα| in the throttle valve opening is set to a predetermined value Δα1 (>Δα0
) Determine whether or not the above is true.
【００２２】変化量が所定量Δα１ 以上でスロットル
弁の動きがまだ大きい場合には、再度ステップ２０へ戻
って同様の空燃比制御を継続するがΔαが所定値Δα１
未満となって安定した後はステップ１３へ戻って前記
した空燃比制御を再開する。このように、空燃比状態を
予測し、かつ、該予測値を修正することにより吸入空気
流量検出手段が故障した場合でも機関の運転を続行でき
るのである。また、吸入空気流量検出手段を用いた空燃
比制御装置に適用して吸入空気流量検出手段の検出精度
低下や過渡状態における応答遅れを補正して制御性能を
より高めるなど、吸入空気流量検出手段の信頼性を高め
たり精度を補償したりすることができる。If the amount of change is greater than the predetermined amount Δα1 and the movement of the throttle valve is still large, the process returns to step 20 and the same air-fuel ratio control is continued, but when Δα is the predetermined value Δα1.
After it becomes stable, the process returns to step 13 and the above-described air-fuel ratio control is restarted. In this way, by predicting the air-fuel ratio state and correcting the predicted value, engine operation can be continued even if the intake air flow rate detection means fails. In addition, it can be applied to an air-fuel ratio control device using an intake air flow rate detection means to further improve control performance by correcting a decrease in the detection accuracy of the intake air flow rate detection means and a response delay in a transient state. It can increase reliability and compensate for accuracy.
【００２３】尚、図４及び図５において、ステップ４，
１４の部分が空燃比ずれ量推定手段に相当し、ステップ
１５の部分が仮定正誤判定手段に相当し、ステップ１７
の部分が仮定修正手段に相当する。また、本実施例では
、目標空燃比として理論空燃比を設定した場合について
示したが、他の任意の目標空燃比に対して適用できるこ
とは勿論である。Note that in FIGS. 4 and 5, step 4,
14 corresponds to an air-fuel ratio deviation amount estimating means, a step 15 corresponds to an assumption correctness determination means, and a step 17
The part corresponds to the assumption correction means. Further, in this embodiment, the case where the stoichiometric air-fuel ratio is set as the target air-fuel ratio is shown, but it goes without saying that the present invention can be applied to any other target air-fuel ratio.
【００２４】[0024]
【発明の効果】以上説明したように本発明によれば、吸
入空気流量検出手段が故障した場合でも機関の運転を続
行でき、また、吸入空気流量検出手段を用いた空燃比制
御装置に適用して吸入空気流量検出手段の検出精度や過
渡状態における応答遅れを補正して制御性能をより高め
るなど、吸入空気流量検出手段の信頼性を高めたり精度
を補償したりすることができる。[Effects of the Invention] As explained above, according to the present invention, even if the intake air flow rate detection means fails, engine operation can be continued, and it can also be applied to an air-fuel ratio control device using the intake air flow rate detection means. It is possible to improve the reliability and compensate for the accuracy of the intake air flow rate detection means by correcting the detection accuracy of the intake air flow rate detection means and the response delay in a transient state to further improve control performance.
【図１】本発明の構成を示すブロック図[Fig. 1] Block diagram showing the configuration of the present invention
【図２】本発明
の一実施例の構成を示す図[Fig. 2] A diagram showing the configuration of an embodiment of the present invention.
【図３】空燃比のリッチ側へ
のずれに対する筒内圧特性の変化及びリーン側へのずれ
に対する筒内圧特性の変化を示す線図[Fig. 3] Diagram showing changes in cylinder pressure characteristics as the air-fuel ratio shifts toward the rich side and changes in the cylinder pressure characteristics as the air-fuel ratio shifts toward the lean side.
【図４】同上実施例の制御ルーチンを示すフローチャー
ト[Fig. 4] Flowchart showing the control routine of the embodiment same as above.
【図５】同上実施例の制御ルーチンを示すフローチャー
ト[Fig. 5] Flowchart showing the control routine of the embodiment same as above.
【図６】吸入空気流量の各種検出手段の概要を示す図[Figure 6] Diagram showing an overview of various detection means for intake air flow rate
２ 筒内圧センサ
４ Ｐｍａｘ ・θＰｍａｘ検出回路５
クランク角センサ
６ マイクロコンピュータ2 Cylinder pressure sensor 4 Pmax/θPmax detection circuit 5
Crank angle sensor 6 Microcomputer
Claims (1)
、検出された筒内圧の燃焼行程毎のピーク値と該ピーク
値を与えるクランク角度とを検出する筒内圧ピーク値・
クランク角度検出手段と、前記検出された筒内圧ピーク
値とクランク角度とに基づいて現在の空燃比の目標空燃
比からのずれ量を推定する空燃比ずれ量推定手段と、前
記推定された空燃比のずれ量が目標空燃比に対してリッ
チ側であるかリーン側であるかを仮定するリッチ・リー
ン仮定手段と、前記推定された空燃比のずれ量とそのリ
ッチ側又はリーン側の仮定により空燃比を目標空燃比に
近づけるべく燃料供給量を設定する燃料供給量設定手段
と、前記推定された空燃比のずれ量の変化状態に応じて
リッチ・リーンの仮定が正しいか否かを判定する仮定正
誤判定手段と、前記判定手段による判定結果に応じてリ
ッチ・リーン仮定手段による仮定を修正する仮定修正手
段とを備えて構成したことを特徴とする内燃機関の空燃
比制御装置。1. A cylinder pressure detection means for detecting the cylinder pressure of an engine; a cylinder pressure peak value for detecting the peak value of the detected cylinder pressure for each combustion stroke and a crank angle that provides the peak value;
crank angle detection means; air-fuel ratio deviation amount estimating means for estimating a deviation amount of the current air-fuel ratio from the target air-fuel ratio based on the detected in-cylinder pressure peak value and the crank angle; and the estimated air-fuel ratio. rich/lean assumption means for assuming whether the deviation amount of the air-fuel ratio is on the rich side or lean side with respect to the target air-fuel ratio; a fuel supply amount setting means for setting a fuel supply amount to bring the fuel ratio closer to a target air-fuel ratio; and an assumption for determining whether the rich-lean assumption is correct according to a change state of the estimated air-fuel ratio deviation amount. 1. An air-fuel ratio control device for an internal combustion engine, comprising: correctness/incorrect determination means; and assumption correction means for correcting the assumption made by the rich/lean assumption means in accordance with the determination result by the determination means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3218799A JP2579565B2 (en) | 1991-08-29 | 1991-08-29 | Air-fuel ratio control device for internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3218799A JP2579565B2 (en) | 1991-08-29 | 1991-08-29 | Air-fuel ratio control device for internal combustion engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04358735A true JPH04358735A (en) | 1992-12-11 |
| JP2579565B2 JP2579565B2 (en) | 1997-02-05 |
Family
ID=16725547
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3218799A Expired - Lifetime JP2579565B2 (en) | 1991-08-29 | 1991-08-29 | Air-fuel ratio control device for internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2579565B2 (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57163128A (en) * | 1981-04-01 | 1982-10-07 | Nissan Motor Co Ltd | Air-fuel ratio controlling apparatus of internal combustion engine |
| JPS58107826A (en) * | 1981-12-22 | 1983-06-27 | Nissan Motor Co Ltd | Electronically controlled fuel injection device of engine |
-
1991
- 1991-08-29 JP JP3218799A patent/JP2579565B2/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57163128A (en) * | 1981-04-01 | 1982-10-07 | Nissan Motor Co Ltd | Air-fuel ratio controlling apparatus of internal combustion engine |
| JPS58107826A (en) * | 1981-12-22 | 1983-06-27 | Nissan Motor Co Ltd | Electronically controlled fuel injection device of engine |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2579565B2 (en) | 1997-02-05 |
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