JP2579565B2 - Air-fuel ratio control device for internal combustion engine - Google Patents
Air-fuel ratio control device for internal combustion engineInfo
- Publication number
- JP2579565B2 JP2579565B2 JP3218799A JP21879991A JP2579565B2 JP 2579565 B2 JP2579565 B2 JP 2579565B2 JP 3218799 A JP3218799 A JP 3218799A JP 21879991 A JP21879991 A JP 21879991A JP 2579565 B2 JP2579565 B2 JP 2579565B2
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- JP
- Japan
- Prior art keywords
- fuel ratio
- air
- deviation
- amount
- assumption
- 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.)
- Expired - Lifetime
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- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
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２
６３頁等参照) 。2. Description of the Related Art A conventional air-fuel ratio control device for an internal combustion engine measures intake air flow using various intake air flow detecting means as shown in FIGS. 6A to 6C. Generally, the air supply ratio is controlled by determining the fuel supply amount based on the fuel supply amount. FIG. 6A shows a vane type in which the amount of rotation of the vane which rotates in response to the intake pressure is detected by a potentiometer to detect the intake air flow rate.
FIG. 2B is a hot wire type in which the current to the bridge circuit is controlled based on a change in the resistance value of the hot wire resistance according to the intake flow rate, and the control current value is detected as the intake air flow rate;
FIG. 5C shows a Karman vortex type in which the amount of vortex downstream of the probe is measured to detect the intake air flow rate (published by Sankaido Co., Ltd. on October 15, 1980, “Automotive Engineering Encyclopedia”. 10-volume electrical equipment, vehicle body equipment, engine parts ”second
See page 63).
【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。However, in such an air-fuel ratio control system which detects the intake air flow rate, the above-mentioned intake air flow rate detecting means is not affected by the atmospheric pressure, humidity and temperature. As a result, it is conceivable that the detection accuracy decreases, a response delay occurs in a transient state, or a failure occurs due to some influence. In such a case, the engine cannot execute accurate air-fuel ratio control,
In the worst case, the operation may be stopped.
【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 such a conventional problem, and controls the fuel supply amount in accordance with the estimated air-fuel ratio state by detecting the in-cylinder pressure, and based on the control result. Accordingly, it is an object of the present invention to provide an air-fuel ratio control device for an internal combustion engine in which the estimation of the air-fuel ratio state is made reliable and the correction control is performed so that the air-fuel ratio approaches 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、燃料供給量を設定する燃料供給量設定手段と、 設
定された燃料供給量の下での燃焼に基づいて、前記筒内
圧ピーク値・クランク角度検出手段により検出された筒
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補正して設定する
燃料供給量補正手段と、補正された燃料供給量の下での
燃焼について、前記筒内圧ピーク値・クランク角度検出
手段により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
定する補正後空燃比ずれ量推定手段と、 燃料供給量補正
前の空燃比ずれ量と補正後空燃比ずれ量とを比較して、
ずれ量が拡大しているか否かにより、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。Therefore, an air-fuel ratio control apparatus for an internal combustion engine according to the present invention, as shown in FIG. 1, comprises an in-cylinder pressure detecting means for detecting an in-cylinder pressure of the engine, cylinder pressure peak value crank angle detecting means for detecting a crank angle providing the peak value and the peak value for each combustion stroke, and the fuel supply quantity setting means for setting a fuel supply amount, setting
Based on the combustion under the specified fuel supply,
Air-fuel ratio deviation estimating means for estimating a deviation amount of a current air-fuel ratio from a target air-fuel ratio based on the in-cylinder pressure peak value detected by the pressure peak value / crank angle detecting means and the crank angle; 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, and the estimated deviation amount of the air-fuel ratio and its assumption on the rich side or lean side. the fuel supply quantity correcting means for setting and correcting the fuel supply quantity to approximate the air-fuel ratio to the target air-fuel ratio, under the corrected fuel supply amount
For combustion, the cylinder pressure peak value / crank angle detection
Cylinder pressure peak value and crank angle detected by
The deviation of the current air-fuel ratio from the target air-fuel ratio based on the
The corrected air-fuel ratio deviation estimating means and the fuel supply amount correction
By comparing the previous air-fuel ratio deviation amount with the corrected air-fuel ratio deviation amount,
An assumption that determines whether the rich / lean assumption is correct based on whether or not the amount of deviation is increased, and an assumption that corrects the assumption by the rich / lean assumption means in accordance with the determination result by the determination means. And a correcting means.
【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、燃料供給量設定手段によ
り設定された燃料供給量の下で前記筒内圧ピーク値・ク
ランク角度検出手段により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。The peak value of the in-cylinder pressure detected by the in-cylinder pressure detecting means for each combustion stroke and the crank angle giving the peak value are detected by the in-cylinder pressure peak value / crank angle detecting means. The air-fuel ratio deviation estimating means is provided by the fuel supply amount setting means.
Under the set fuel supply amount, the in-cylinder pressure peak value
Based on the peak value of the in-cylinder pressure detected by the rank angle detecting means and the crank angle, the deviation amount of the current air-fuel ratio from the target air-fuel ratio is estimated, and the rich / lean assuming means estimates the deviation amount as the target air-fuel ratio. On the other hand, it is assumed that it is shifted to the rich side or to the lean side.
【０００７】燃料供給量補正手段は前記空燃比ずれ量推
定手段で推定された現状空燃比の目標空燃比に対するず
れ量と前記リッチ・リーン仮定手段によるリッチ・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
く燃料供給量を補正して設定する。補正後空燃比ずれ量
推定手段は、前記補正された燃料供給量の下での燃焼に
ついて、前記筒内圧ピーク値・クランク角度検出手段に
より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。仮定正誤判定手段は、燃料供給量補正前の空燃比ず
れ量と補正後空燃比ずれ量とを比較して、ずれ量が拡大
しているか否かにより、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 correcting means estimates the air-fuel ratio deviation amount.
The fuel supply amount is corrected and set so that the air-fuel ratio approaches the target air-fuel ratio based on the amount of deviation of the current air-fuel ratio from the target air-fuel ratio estimated by the determining means and the rich-lean assumption by the rich-lean assumption means. I do. Air-fuel ratio deviation after correction
The estimating means performs combustion under the corrected fuel supply amount.
About the in-cylinder pressure peak value / crank angle detecting means.
Based on the detected in-cylinder pressure peak value and crank angle
To estimate the deviation of the current air-fuel ratio from the target air-fuel ratio.
You. The assumption correct / wrong determining means compares the air-fuel ratio deviation amount before the fuel supply amount correction and the corrected air-fuel ratio deviation amount, and determines whether the rich / lean assumption is correct based on whether the deviation amount is enlarged. Is determined, and the assumption correcting means corrects the rich / lean assumption based on the determination result.
【０００８】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Ｔ 0 に相当する燃料量が燃料噴射弁９から噴射
される。ここで、該燃料噴射量の初期値Ｔ 0 を決定する
機能が燃料供給量設定手段に相当する。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] Based on the above premise, the microcomputer
The air-fuel ratio control performed by the computer 6 is shown in FIGS.
The description will be given according to the flow chart shown. Steps (in the diagram
Is denoted as S. In the following, the intake air flow rate and air-fuel ratio
Fuel injection amount determined based on the preset initial value of
A fuel amount corresponding to the initial value T 0 is injected from the fuel injection valve 9.
Is done. Here, the initial value T 0 of the fuel injection amount is determined.
The function corresponds to a fuel supply amount setting unit. By correcting the rich / lean assumption in the correct direction in this manner, it is possible to control the air-fuel ratio to approach the target air-fuel ratio correctly.
【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 ・θPmax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Ｐmax 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。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2 showing the configuration of one embodiment, an in-cylinder pressure sensor (in-cylinder pressure detecting means) 2 for detecting an in-cylinder pressure is attached to a portion where an ignition plug 1 is seated on a cylinder head.
Cylinder pressure signal from the input to the P max · θ Pmax detecting circuit 4 through an amplifier 3. Crank angle signal P max · theta Pmax detection circuit 4 from other crank angle sensor 5 of the in-cylinder pressure signal is also inputted, for each combustion stroke of the cylinder where the cylinder pressure sensor 2 is attached, the peak value P max of the in-cylinder pressure Is detected. That is,
P max · theta Pmax detecting circuit 4 and the crank angle sensor 5 and in-cylinder pressure peak crank angle detection means is constituted.
【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 the crank angle θPmax for each combustion stroke detected in this way are input to the microcomputer 6. Microcomputer 6
Controls the air-fuel ratio by estimating the amount of deviation of the current air-fuel ratio from the target air-fuel ratio based on each of the detected values and setting the fuel supply amount assuming that the air-fuel ratio is rich or lean. On the other hand, the deviation amount of the air-fuel ratio for each operating condition such as constant speed, acceleration, and start detected by the state of the throttle valve opening α detected by the throttle sensor 7 and the cooling water temperature T W detected by the water temperature sensor 8. Judge whether the rich / lean assumption is right or wrong according to the change state of
If not, correct the assumptions.
【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 is for injecting and supplying a set amount of fuel to the engine, thereby controlling the air-fuel ratio. Next, the operation will be described. First, consider the case where the stoichiometric air-fuel ratio is set as the target air-fuel ratio. FIG. 3 shows an in-cylinder pressure waveform with respect to the air-fuel ratio. In other words, the in-cylinder pressure changes substantially in the same manner regardless of whether the target air-fuel ratio is shifted to the rich side or the lean side. Therefore, if it is known whether the air-fuel ratio is shifted to the rich side or the lean side,
The predicted value of the air-fuel ratio is determined by the pattern of the in-cylinder pressure change.
【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。The air-fuel ratio control performed by the microcomputer 6 based on the above premise will be described with reference to the flowcharts shown in FIGS. In step (denoted as S in the figure; the same applies hereinafter), in step 1, the fuel amount corresponding to the initial value T 0 of the fuel injection amount determined based on the preset initial value of the intake air flow rate and the air-fuel ratio is determined. Injected from.
【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θPmaxとを入力する。In step 2, it is determined whether or not the combustion stroke of the cylinder (hereinafter referred to as a specific cylinder) to which the in-cylinder pressure sensor 2 is mounted has been completed, based on a cylinder discrimination signal from the crank angle sensor 5, and the end of the combustion stroke is determined. Then, proceed to step 3.
In step 3, the peak value P max of the in-cylinder pressure for each combustion stroke detected by the P max · θ Pmax detection circuit 4 and the crank angle θ Pmax at the time when the P max occurs are input.
【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。The program then proceeds to step 4, to estimate the amount of deviation from the target air-fuel ratio on the basis of the P max and theta Pmax input in step 3. More specifically, this is set by searching a three-dimensional map stored in the ROM of the microcomputer 6, for example, from the relationship between the in-cylinder pressure and the air-fuel ratio shown in FIG. In step 5, step when the change amount [Delta] [alpha] per unit time Δt on the basis of the valve opening degree α signals from the throttle sensor 7 determines whether acceleration or not exceeding a predetermined positive value [Delta] [alpha] 0, it is determined accelerated It is assumed that the process proceeds to step 6 and proceeds to step 6 in order to increase the fuel injection amount of the next time (after Δt seconds) with respect to the increase in the intake air flow rate, and the air-fuel ratio is 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。On the other hand, if the determination in step 5 is NO, the process proceeds to step 7 where the amount of change .DELTA..alpha.
It is determined whether or not the vehicle is decelerating below Δα 0, and if it is determined that the vehicle is decelerating, the process proceeds to step 8 and the air-fuel ratio shifts to the rich side in order to correct the next fuel injection amount to reduce the intake air flow rate. Assume that The determination in step 7 is NO
(−Δα 0 ≦ α ≦ Δα 0 ) In the steady state, the process proceeds to step 9 and the cooling water temperature T W detected by the water temperature sensor 8.
It is determined whether the engine is started and warmed up at a set value T W0 (for example, 60 ° C.) or less. If YES, a step is taken to increase the combustion temperature by increasing the combustion temperature by leaning the air-fuel ratio. 8 and assuming that the current air-fuel ratio is shifted to the rich side,
When the warm-up is substantially completed (NO), the process proceeds to step 10 and the same assumption as the previous (Δt seconds ago) is maintained. still,
At the first time after the start of control, the initial assumption (rich or lean) is set.
【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13で
新たに検出されたＰmax ，θPmaxを入力する。In step 11, based on the deviation of the air-fuel ratio estimated in step 4 and the assumption of the deviation direction in steps 6, 8, and 10, the fuel injection amount is set to an initial value so as to approach the target air-fuel ratio. It is set by performing increase / decrease correction.
Next, in step 12, it is determined whether or not the fuel of the set fuel injection amount has been supplied to the specific cylinder and combustion has been terminated, based on the cylinder discrimination signal. After the completion of the combustion stroke, Pmax newly detected in step 13 is determined. , Θ Pmax .
【００１７】ステップ14では、前記Ｐmax ，θPmax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。[0017] At step 14, the P max, sets the shift amount from an air-fuel ratio based on the theta Pmax. In step 15, the deviation amount of the air-fuel ratio estimated in step 14 this time is compared with the deviation amount estimated in the previous time, and whether the previous rich / lean assumption was correct is determined based on whether the deviation amount is expanded. I 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
ステップ11にて燃料噴射量を補正して設定して空燃比制
御を行う。That is, if the rich / lean assumption is correct, the correction of the increase / decrease of the fuel injection amount performed in the correct direction is performed in the correct direction, so that the in-cylinder pressure increases and the deviation amount of the air-fuel ratio decreases. Therefore, it is determined in step 15 that the assumption is correct. In this case, after resetting the erroneous determination repetition counter to 0 in step 16, the process returns to step 5 again based on the rich / lean assumption according to the operating conditions and the friction amount of the air-fuel ratio estimated in step 14.
In step 11, the fuel injection amount is corrected and set, and the air-fuel ratio control is performed.
【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, the process proceeds to step 17, and the present assumption is reversed to the previous assumption (if rich, Lean, rich if lean). Then after counting up the counter C repeatedly indetermination in step 18, the count value C of the counter proceeds to step 19 to determine whether a predetermined value C 0 or more to Step 5 and when less than the predetermined value C 0 The process returns to step 20 if the value is equal to or greater than the predetermined value C 0 .
【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。That is, in a relatively stable state in which the air-fuel ratio does not repeat rich / lean many times, the air-fuel ratio converges to the target air-fuel ratio by correcting the deviation of the air-fuel ratio and the assumption of the rich / lean. Can be done. On the other hand, the air-fuel ratio sometimes repeats rich / lean during sudden acceleration / deceleration with the throttle valve opening changed abruptly. Therefore, even if the air-fuel ratio control is performed, the reliability is poor, so that the fluctuation of the air-fuel ratio may be rather increased.
【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。For this reason, if it is determined in step 19 that the correction of the rich / lean assumption has been continuously performed a predetermined number of times C 0 , it is determined that the above-mentioned rapid increase / decrease operation has been performed and step 20 is performed. Then, the fuel injection amount is set in accordance with a predetermined constant reference air-fuel ratio. Then, after it is determined in step 21 that the combustion has been completed for the set fuel injection amount, the process proceeds to step 22, where the change amount | Δα | of the throttle valve opening is equal to or more than a predetermined value Δα 1 (> Δα 0 ). Is determined.
【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。[0022] When the amount of change is still large movement of the throttle valve by a predetermined amount [Delta] [alpha] 1 or more, but continues the same air-fuel ratio control returns to step 20 again stable becomes [Delta] [alpha] is less than the predetermined value [Delta] [alpha] 1 Thereafter, the flow returns to step 13 to restart the above-described air-fuel ratio control. Thus, the air-fuel ratio state is predicted,
In addition, by correcting the predicted value, the operation of the engine can be continued even when the intake air flow rate detecting means breaks down. In addition, the present invention is applied to an air-fuel ratio control device using an intake air flow rate detecting means, and the detection accuracy of the intake air flow rate detecting means is reduced, and response delay in a transient state is corrected to improve control performance. Reliability can be improved and accuracy can be compensated.
【００２３】尚、図４及び図５において、ステップ４の
部分が空燃比ずれ量推定手段に相当し、ステップ11の部
分が燃料供給量補正手段に相当し、ステップ14の部分が
補正後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。[0023] Incidentally, in FIG. 4 and FIG. 5, <br/> part of Step 4 corresponds to the air-fuel ratio shift amount estimating means, part of step 11
The minute corresponds to the fuel supply amount correction means, and the portion of step 14 is
The corrected air-fuel ratio deviation amount estimating means corresponds to step S15, and the step S15 corresponds to assumed correctness determining means. The step S17 corresponds to assumed correction means. Further, in the present embodiment, the case where the stoichiometric air-fuel ratio is set as the target air-fuel ratio has been described.
Of course, it 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。As described above, according to the present invention, the operation of the engine can be continued even if the intake air flow detecting means fails, and the present invention is applied to an air-fuel ratio control device using the intake air flow detecting means. Thus, the reliability of the intake air flow detecting means can be enhanced or the accuracy can be compensated, for example, by correcting the detection accuracy of the intake air flow detecting means or the response delay in a transient state to improve the control performance.
【図１】本発明の構成を示すブロック図FIG. 1 is a 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 is a diagram showing a 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 is a diagram showing a change in in-cylinder pressure characteristics with respect to a shift of an air-fuel ratio toward a rich side and a change in a cylinder pressure characteristic with respect to a shift toward a 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 is a flowchart showing a control routine of the embodiment.
【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 is a flowchart showing a control routine of the embodiment.
【図６】吸入空気流量の各種検出手段の概要を示す図FIG. 6 is a diagram showing an outline of various detection means for detecting an 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 P max · θ Pmax detecting circuit 5 crank angle sensor 6 microcomputer
Claims (1)
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、燃料供給量を設定する燃料供給量設定手段と、 設定された燃料供給量の下での燃焼に基づいて、前記筒
内圧ピーク値・クランク角度検出手段により 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
料供給量を補正して設定する燃料供給量補正手段と、補正された燃料供給量の下での燃焼について、前記筒内
圧ピーク値・クランク角度検出手段により検出された筒
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補正後空燃比ずれ
量推定手段と、 燃料供給量補正前の空燃比ずれ量と補正後空燃比ずれ量
とを比較して、ずれ量が拡大しているか否かにより、 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. An in-cylinder pressure detecting means for detecting an in-cylinder pressure of an engine, and an in-cylinder pressure peak value / crank angle detection for detecting a peak value of the detected in-cylinder pressure for each combustion stroke and a crank angle giving the peak value. Means, a fuel supply amount setting means for setting a fuel supply amount, and the cylinder based on combustion under the set fuel supply amount.
Air-fuel ratio deviation estimating means for estimating a deviation amount of a current air-fuel ratio from a target air-fuel ratio based on an in-cylinder pressure peak value and a crank angle detected by an internal pressure peak value / crank angle detecting means; Rich / lean assumption means for assuming whether the deviation amount of the air-fuel ratio is on the rich side or the lean side with respect to the target air-fuel ratio, and the estimated deviation amount of the air-fuel ratio and the assumption on the rich side or the lean side. A fuel supply amount correcting means for correcting and setting the fuel supply amount so as to bring the air-fuel ratio closer to the target air-fuel ratio, and performing combustion in the cylinder under the corrected fuel supply amount.
Cylinder detected by pressure peak value / crank angle detection means
The current air-fuel ratio based on the internal pressure peak value and the crank angle
Air-fuel ratio deviation to estimate deviation from target air-fuel ratio
Amount estimating means, air-fuel ratio deviation before and after correction of fuel supply amount
And an assumption correct / incorrect determining means for determining whether the rich / lean assumption is correct based on whether or not the amount of deviation is increased; and a rich / lean assuming means in accordance with the determination result by the determining means. An air-fuel ratio control device for an internal combustion engine, comprising: an assumption correcting means for correcting an assumption based on the above.
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 JPH04358735A (en) | 1992-12-11 |
| JP2579565B2 true 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 |
|---|---|
| JPH04358735A (en) | 1992-12-11 |
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