JPH0476244A - Air-fuel ratio controller - Google Patents
Air-fuel ratio controllerInfo
- Publication number
- JPH0476244A JPH0476244A JP2189227A JP18922790A JPH0476244A JP H0476244 A JPH0476244 A JP H0476244A JP 2189227 A JP2189227 A JP 2189227A JP 18922790 A JP18922790 A JP 18922790A JP H0476244 A JPH0476244 A JP H0476244A
- Authority
- JP
- Japan
- Prior art keywords
- air
- fuel ratio
- signal
- sensor
- value
- 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 147
- 230000002159 abnormal effect Effects 0.000 claims abstract description 9
- 230000005856 abnormality Effects 0.000 claims description 29
- 239000001301 oxygen Substances 0.000 claims description 9
- 229910052760 oxygen Inorganic materials 0.000 claims description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 8
- 238000002485 combustion reaction Methods 0.000 claims description 8
- 239000007789 gas Substances 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 3
- 230000007257 malfunction Effects 0.000 abstract 4
- 230000007488 abnormal function Effects 0.000 abstract 1
- 238000000034 method Methods 0.000 description 21
- 230000008569 process Effects 0.000 description 20
- 238000002347 injection Methods 0.000 description 13
- 239000007924 injection Substances 0.000 description 13
- 230000004913 activation Effects 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 239000007858 starting material Substances 0.000 description 6
- 239000003054 catalyst Substances 0.000 description 5
- 238000001514 detection method Methods 0.000 description 5
- 238000009792 diffusion process Methods 0.000 description 4
- 230000006870 function Effects 0.000 description 4
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 230000020411 cell activation Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002496 gastric effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000009474 immediate action Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 229910002076 stabilized zirconia Inorganic materials 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
【発明の詳細な説明】
(産業上の利用分野)
本発明は、内燃機関の空燃比情報を空燃比センサより取
り込むことにより、内燃機関の空燃比を制御する空燃比
制御装置に関する。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an air-fuel ratio control device that controls the air-fuel ratio of an internal combustion engine by taking in air-fuel ratio information of the internal combustion engine from an air-fuel ratio sensor.
(従来の技術)
従来、ジルコニアの酸素濃度電池作用と酸素イオンポン
ピング作用という特性を利用して、空燃比(A/F)を
単にストイキオよりもリーン側かリッチ側かだけでなく
、どの程度の値であるか検出するリニアA/Fセンサが
提案されている。(特開昭63−36’ 140号公報
参照)このリニアA/Fセンサは第8図に示すように、
その基部が各々安定化ジルコニア素子であるセンサセル
20とポンプセル21とを絶縁層22を介して結合して
構成される。両セルには排ガスの通過する拡散口23.
24が形成され、絶縁層22内には拡散口23、24か
らの排ガスを収容する検出室25が形成され、これらに
より、拡散律速体が構成されている。(Prior art) Conventionally, the characteristics of zirconia's oxygen concentration cell action and oxygen ion pumping action have been used to determine not only whether the air-fuel ratio (A/F) is leaner or richer than stoichiometry, but also how much. A linear A/F sensor has been proposed that detects whether the current value is the same or not. (Refer to Japanese Patent Application Laid-Open No. 63-36'140) As shown in FIG. 8, this linear A/F sensor has the following features:
The sensor cell 20 and the pump cell 21, each of which has a stabilized zirconia element at its base, are connected via an insulating layer 22. Both cells have diffusion ports 23 through which exhaust gas passes.
24 is formed, and a detection chamber 25 is formed in the insulating layer 22 to accommodate the exhaust gas from the diffusion ports 23 and 24, thereby forming a diffusion control body.
また、絶縁層22にはリファレンス室25aが形成され
、ここに参照気体例えば大気を導くように構成されてい
る。第9図に示すように、両セルには触媒を兼ねて白金
の電極26.27.28.29が設けてあり、これらに
は多数の微***があけられている。Further, a reference chamber 25a is formed in the insulating layer 22, and is configured to introduce a reference gas, such as the atmosphere, into the reference chamber 25a. As shown in FIG. 9, both cells are provided with platinum electrodes 26, 27, 28, and 29 which also serve as catalysts, and a large number of microholes are formed in these electrodes.
30は電気ヒータであり、セル全体を例えば800±1
00℃に加熱して各セルを活性状態で作動させている。30 is an electric heater, which heats the entire cell for example at 800±1
Each cell is operated in an active state by heating to 00°C.
この両セル20.21はセンサ即動回路SCに接続され
ている。Both cells 20,21 are connected to a sensor immediate circuit SC.
センサセル20は従来の02センサと同様の原理で電極
26.27間に酸素濃度差があると起電力を生じる性質
を備え、ポンプセル21は逆に電極28.29間に強制
的にポンプ電流Ipが流されると酸素をマイナス電極側
からプラス電極側に汲み出す性質を備えている。The sensor cell 20 has the same principle as the conventional 02 sensor, and has the property of generating an electromotive force when there is an oxygen concentration difference between the electrodes 26 and 27. On the contrary, the pump cell 21 has the property that a pump current Ip is forcibly generated between the electrodes 28 and 29. It has the property of pumping oxygen from the negative electrode side to the positive electrode side when flowing.
そこで、制御部31にてセンサセル20の起電力VSを
検出し、この起電力Vsを一定に保つように、即ち検出
室25内または拡散孔23.24内をストイキオに対応
する酸素濃度に保つようにポンプ電流工pをフィードバ
ック制御する。これにより、ポンプ電流Ipは第10図
に示すように空燃比に対して連続的に変化するので、ポ
ンプ電流Ipから空燃比を算出することが出来る。Therefore, the control unit 31 detects the electromotive force VS of the sensor cell 20, and controls to keep the electromotive force Vs constant, that is, to maintain the oxygen concentration in the detection chamber 25 or the diffusion hole 23, 24 at an oxygen concentration corresponding to stoichiometry. The pump current p is feedback-controlled. As a result, the pump current Ip changes continuously with respect to the air-fuel ratio as shown in FIG. 10, so the air-fuel ratio can be calculated from the pump current Ip.
制御部31としては、比較回路1にてセンサセル20の
起電力Vsをストイキオ相当の参照電圧Vrefと比較
し、比較回路1の出力を正負電源付き積分アンプ2で積
分し、その積分出力でポンプセル21にポンプ電流■ρ
を流す。The control unit 31 uses a comparison circuit 1 to compare the electromotive force Vs of the sensor cell 20 with a reference voltage Vref equivalent to stoichiometry, integrates the output of the comparison circuit 1 with an integrating amplifier 2 with positive and negative power supplies, and uses the integrated output to control the pump cell 21. Pump current ■ρ
flow.
そして、ポンプ電流Ipの回路に電流検出用の抵抗器5
を介装し、抵抗器の降下電圧から電流検出回路3により
ポンプ電流Ipを検出している。A resistor 5 for current detection is added to the pump current Ip circuit.
A pump current Ip is detected by a current detection circuit 3 from the voltage drop across the resistor.
更に、回路3の出力を加算回路4に入力し、下式の処理
により、たとえば、0〜5ボルトの信号V。UTにより
、空燃比(A/F)を表す様にしている。Furthermore, the output of the circuit 3 is input to the adder circuit 4, and the signal V of 0 to 5 volts, for example, is obtained by processing the following formula. UT represents the air-fuel ratio (A/F).
■。、、T=G・I p + V srp但し、Gは電
流−電圧変換ゲイン、V 5TPはステップアップ電圧
である。■. , , T=G·I p + V srp where G is a current-voltage conversion gain and V 5TP is a step-up voltage.
処で、内燃機関は空燃比を目標空燃比に調整すべく、空
燃比センサからの空燃比情報に基づきフィードバック制
御を行っている。例えば、空燃比をストイキオ近傍の狭
いウィンドウ内に制御することにより、排気系に用いら
れる三元触媒を効率良く作動させている。あるいは、リ
ーンNO工触媒及び三元触媒を排気系に備えたリーンバ
ーンエンジンの場合は、その空燃比を目標値である所定
のリーン側の値に保持すべく、リニアA/Fセンサから
の空燃比情報に基づきフィードバック制御を行っている
。In order to adjust the air-fuel ratio to a target air-fuel ratio, the internal combustion engine performs feedback control based on air-fuel ratio information from an air-fuel ratio sensor. For example, by controlling the air-fuel ratio within a narrow window near the stoichiometry, a three-way catalyst used in the exhaust system is operated efficiently. Alternatively, in the case of a lean burn engine equipped with a lean NO catalyst and a three-way catalyst in the exhaust system, air from the linear A/F sensor is Feedback control is performed based on fuel ratio information.
このように内燃機関を駆動させる上で、空燃比を目標値
に精度良く制御することは燃費の向上、機関出力の向上
、アイドル回転の安定化、排ガスの改善、ドライバビリ
ティ−の改善の上で極めて重要である。このため、この
空燃比情報が得られるリニアA/Fセンサの空燃比情報
が常時安定して出力されることが必要である。In driving an internal combustion engine, accurately controlling the air-fuel ratio to the target value improves fuel efficiency, increases engine output, stabilizes idle speed, reduces exhaust gas, and improves drivability. extremely important. Therefore, it is necessary that the air-fuel ratio information of the linear A/F sensor from which this air-fuel ratio information is obtained is always stably output.
(発明が解決しようとする課題)
処で、リニアA/Fセンサはこれが使用される雰囲気が
、ストイキオにある場合は問題ないが、リーン雰囲気下
で定常運転を連続して行うような場合に、その空燃比信
号V。IJTが第5図に示すような特性を示すことがあ
る。(Problem to be Solved by the Invention) The linear A/F sensor has no problem when the atmosphere in which it is used is stoichiometric, but when it is continuously operated in a lean atmosphere, Its air-fuel ratio signal V. IJTs may exhibit characteristics as shown in FIG.
即ち、エンジンが一定の目標空燃比(リーンの値)を設
定されて定常運転製連続して行うと、時間の経過と共に
その出力である空燃比信号V。UT値が低下する傾向を
示す。That is, when the engine is set to a constant target air-fuel ratio (lean value) and continuously operated in a steady state, the air-fuel ratio signal V which is the output as time passes. The UT value shows a tendency to decrease.
この場合、途中で、エンジンをレーシングさせると、即
ち、−時的に空燃比をリッチに振り、ポンプ電流の向き
を代えると、02検出特性が復帰するものと見做され、
記号ERで示すように空燃比は符号STで示すスタート
時と同様の値に復帰する事も明らかと成っている。In this case, it is assumed that if the engine is raced midway through, that is, if the air-fuel ratio is made richer and the direction of the pump current is changed, the 02 detection characteristic will be restored.
It is also clear that, as indicated by the symbol ER, the air-fuel ratio returns to the same value as at the start, indicated by the symbol ST.
このように、リニアA/Fセンサの出力に異常が発生し
た場合、その空燃比情報はその信頼性を低下させること
となる。In this way, if an abnormality occurs in the output of the linear A/F sensor, the reliability of the air-fuel ratio information will be reduced.
そこで、リニアA/Fセンサの異常時にはこれを早期に
検出し、その時の状況に応じて、空燃比センサが復帰可
能な異常か、復帰不可の故障かを判定して、以後の空燃
比のフィードバック制御を中断させたり、それに代わる
制御方式での空燃比制御を選択的に行うことが望ましい
。Therefore, when an abnormality occurs in the linear A/F sensor, it is detected early, and depending on the situation at that time, it is determined whether the air-fuel ratio sensor is in a recoverable abnormality or an unrecoverable failure, and feedback on the air-fuel ratio is provided thereafter. It is desirable to interrupt the control or to selectively control the air-fuel ratio using an alternative control method.
本発明の目的は、空燃比センサの異常状態に適した空燃
比制御を行うことが出来る空燃比制御装置を提供するこ
とにある。An object of the present invention is to provide an air-fuel ratio control device that can perform air-fuel ratio control suitable for an abnormal state of an air-fuel ratio sensor.
(課題を解決するための手段)
上述の目的を達成するために、本発明は、混合気燃焼後
の排ガス中の酸素濃度に応じた空燃比信号を出力する空
燃比センサと、上記空燃比信号と車両の運転状態より決
定された目標空燃比との差分である空燃比ずれ量を算出
するずれ量算出手段と、上記空燃比ずれ量が第一の判定
値を上回ると異常信号を出力する異常判定手段と、上記
空燃比ずれ量が上記第一の判定値より大きな第二の判定
値を上回ると故障信号を出力する故障判定手段と、上記
異常信号が出力された時、上記空燃比信号に基づくフィ
ードバック制御を行う手段による空燃比制御を中断させ
、上記故障信号が出力された時上記空燃比信号に基づく
フィードバック制御を行う手段による空燃比制御を中断
させると共にセンサ作動を停止させる異常処理手段とを
有したことを特徴とする。(Means for Solving the Problems) In order to achieve the above object, the present invention provides an air-fuel ratio sensor that outputs an air-fuel ratio signal according to the oxygen concentration in exhaust gas after combustion of a mixture, and an air-fuel ratio sensor that outputs an air-fuel ratio signal according to the oxygen concentration in exhaust gas after combustion of a mixture. and a deviation amount calculation means for calculating an air-fuel ratio deviation amount which is a difference between the air-fuel ratio deviation amount and a target air-fuel ratio determined from the driving state of the vehicle, and an abnormality that outputs an abnormal signal when the air-fuel ratio deviation amount exceeds a first judgment value. determination means; a failure determination means for outputting a failure signal when the air-fuel ratio deviation amount exceeds a second determination value that is larger than the first determination value; abnormality processing means for interrupting the air-fuel ratio control by the means for performing feedback control based on the air-fuel ratio signal, and interrupting the air-fuel ratio control by the means for performing feedback control based on the air-fuel ratio signal and stopping sensor operation when the failure signal is output; It is characterized by having the following.
(作 用)
異常処理手段が異常信号を受けると、空燃比信号に基づ
くフィードバック制御を行う手段による空燃比制御を中
断させるのみとし、故障信号を受けると空燃比信号に基
づくフィードバック制御を行う手段による空燃比制御を
中断させると共にセンサ作動を停止させるので、異常処
理手段が異常信号を受けた場合にはセンサの復帰を待つ
事が出来る。(Function) When the abnormality processing means receives an abnormality signal, it only interrupts the air-fuel ratio control by the means for performing feedback control based on the air-fuel ratio signal, and when it receives a failure signal, it interrupts the air-fuel ratio control by the means for performing feedback control based on the air-fuel ratio signal. Since the air-fuel ratio control is interrupted and the sensor operation is stopped, when the abnormality processing means receives an abnormality signal, it can wait for the sensor to return.
(実 施 例)
第1図に示した空燃比制御装置は、内燃機関の燃料供給
系内に配設されている。(Embodiment) The air-fuel ratio control device shown in FIG. 1 is disposed within a fuel supply system of an internal combustion engine.
この燃料供給系は、エンジン10の排気路11に配設さ
れるリニアA/FセンサSより得られた空燃比(A/F
) 情報をエンジンコントロールユニット(以後単にコ
ントローラと記す)12に出力し、このコントローラが
燃料供給量を算出し、その供給量の燃料を噴射ノズルN
が適時に吸気路13に噴射供給するという構成を採る。This fuel supply system uses an air-fuel ratio (A/F
) The information is output to the engine control unit (hereinafter simply referred to as controller) 12, this controller calculates the fuel supply amount, and injects the fuel of the supplied amount into the injection nozzle N.
A configuration is adopted in which the fuel is injected and supplied to the intake passage 13 at a proper time.
ここでリニアA/FセンサS及びセンサ即動回路SCは
第9図に示した従来装置と同じ構成を採る部分が多く、
その重複説明を略す。Here, most of the linear A/F sensor S and sensor immediate action circuit SC have the same configuration as the conventional device shown in FIG.
The redundant explanation will be omitted.
第1図において、リニアA/FセンサSは0〜5ボルト
の空燃比信号V outをエンジンコントロールユニッ
ト(以後単にコントローラと記憶)12に出力させてお
り、特に、センサ駆動回路SCには異常処理手段の一部
分を成すポンプカット回路14が第3図に示すように接
続されている。In Fig. 1, the linear A/F sensor S outputs an air-fuel ratio signal Vout of 0 to 5 volts to the engine control unit (hereinafter simply referred to as controller) 12, and in particular, the sensor drive circuit SC is sent to the sensor drive circuit SC for abnormality processing. A pump cut circuit 14 forming part of the means is connected as shown in FIG.
このポンプカット回路14は、比較回路1と正負電源付
き積分アンプ2間をゼロ電位、即ち比較回路1の出力が
ストイキオを示す電位に保つトランジスタ15が配設さ
れ、そのベース端にコントローラ12からのポンプカッ
ト入力が入力されるよう構成されている。This pump cut circuit 14 has a transistor 15 that maintains a zero potential between the comparator circuit 1 and the integrating amplifier 2 with positive and negative power supplies, that is, a potential in which the output of the comparator circuit 1 is stoichiometric. The pump cut input is configured to be input.
なお、符号16はエンジンの図示しないコンビネイショ
ンスイッチ内のスタータスイッチを、符号17は吸入空
気量情報を出力するエアフローセンサを、符号18はエ
ンジン回転数情報を出力する回転センサを、符号19は
大気圧情報を出方する大気圧センサをそれぞれ示してい
る。Reference numeral 16 designates a starter switch in a combination switch (not shown) of the engine, reference numeral 17 an air flow sensor that outputs intake air amount information, reference numeral 18 a rotation sensor that outputs engine speed information, and reference numeral 19 a large The atmospheric pressure sensors that output atmospheric pressure information are each shown.
コントローラ12はマイクロコンピュータでその要部が
構成され、特に、各出力信号を受けて、適時にその情報
を取り込み、あるいは適時に制御信号を駆動回路121
,122等に出力する入出力回路123と、第6図(a
)、(b )、(c )及び第7図に示す空燃比制御
プログラムや第4図の各判定値π、α等を書き込まれた
記憶回路124と、各制御プログラムに沿って制御値を
算出する制御回路125等で構成されている。The main part of the controller 12 is made up of a microcomputer, and in particular, it receives each output signal and takes in the information in a timely manner or sends a control signal to the drive circuit 121 in a timely manner.
, 122, etc., and the input/output circuit 123 that outputs to
), (b), (c), and a memory circuit 124 in which the air-fuel ratio control programs shown in FIG. 7 and each judgment value π, α, etc. shown in FIG. It is composed of a control circuit 125 and the like.
ここで、このコントローラ12の機能をこの発明に関し
てのみ説明すると、第2図に示すようになる。Here, the functions of this controller 12 will be explained only with regard to the present invention, as shown in FIG.
即ち、コントローラ12は空燃比センサSの駆動回路S
Cからの空燃比信号V。UTを受けて、この値と目標空
燃比との差分ΔA/F(空燃比ずれ量)を算出するずれ
量算出手段と、異常判定手段と、故障判定手段と、異常
処理手段及び空燃比信号に基づくフィードバック制御を
行う手段として機能する。That is, the controller 12 controls the drive circuit S of the air-fuel ratio sensor S.
Air-fuel ratio signal V from C. A deviation amount calculation means that receives the UT and calculates a difference ΔA/F (air-fuel ratio deviation amount) between this value and the target air-fuel ratio, an abnormality determination means, a failure determination means, an abnormality processing means, and an air-fuel ratio signal. It functions as a means for performing feedback control based on the
異常判定手段は差分ΔA/Fが第一の判定値πを上回る
と異常信号を出力し、故障判定手段は差分ΔA/Fが第
二の判定値αを上回ると故障信号を出力し、異常処理手
段は異常信号が出力された時、空燃比信号に基づくフィ
ードバック制御を行う手段による空燃比制御を中断させ
、故障信号が出力された時空燃比信号に基づくフィード
バック制御を行う手段による空燃比制御を中断させると
共にセンサ作動を停止させる。The abnormality determination means outputs an abnormality signal when the difference ΔA/F exceeds the first determination value π, and the failure determination means outputs a failure signal when the difference ΔA/F exceeds the second determination value α, and performs abnormality processing. The means interrupts the air-fuel ratio control by the means for performing feedback control based on the air-fuel ratio signal when the abnormality signal is output, and interrupts the air-fuel ratio control by the means for performing feedback control based on the air-fuel ratio signal when the failure signal is output. and stop sensor operation.
第4図の示すように、第二の判定値αは第一の判定値π
より大きく設定される。As shown in FIG. 4, the second judgment value α is the first judgment value π
is set larger.
この場合、第一の判定値πは第5図で説明したように、
エンジンが連続リーンの定常運転を連続して行う場合(
符号ENで示す領域)に時間の経過と共に生じる空燃比
信号V。LITの低下を考慮して決定される。この場合
、空燃比フィードバックを中断し、リニアA/Fセンサ
S自体の他方、第二の判定値αは第一の判定値πより十
分に大きく、明らかに、復帰見込の無い故障状態のレベ
ルに信号がすれたと判断出来る値に設定される。In this case, the first judgment value π is as explained in FIG.
When the engine performs continuous lean steady operation (
The air-fuel ratio signal V that occurs over time in the region indicated by the symbol EN. It is determined in consideration of the reduction in LIT. In this case, the air-fuel ratio feedback is interrupted, and the second judgment value α of the linear A/F sensor S itself is sufficiently larger than the first judgment value π, and it is clearly at the level of a failure state with no hope of recovery. It is set to a value that allows it to be determined that the signal has faded.
ここで、このコントローラ37による燃料噴射量の制御
(フィードバック制御及び非フイードバツク時に行われ
るオープンループ制御)と共に行われる空燃比制御処理
を第6図(a)、(b)、(c)及び第7図の制御プロ
グラムと共に説明する。Here, the air-fuel ratio control process performed together with the fuel injection amount control (feedback control and open loop control performed during non-feedback) by the controller 37 is shown in FIGS. 6(a), (b), (c) and 7. This will be explained along with the control program shown in the figure.
コントローラのプログラムは、第6図(c)に示すよう
にスタータスイッチのオン処理によりスタートする。こ
の場合、メインルーチンではヒータ30(第9図参照)
のオン処理がなされ、それに続いてスタータフラグが1
か否か判定し、スタータオン処理がなされていないと、
ステップa8に、再度ステップa2に達し、スタータオ
ンされるとステップa3に進む。The controller program starts by turning on the starter switch as shown in FIG. 6(c). In this case, in the main routine, the heater 30 (see Fig. 9)
is turned on, and then the starter flag is set to 1.
It is determined whether or not, and if the starter-on process is not performed,
When the process reaches step a2 again at step a8 and the starter is turned on, the process proceeds to step a3.
ステップa3ではスタータフラグがクリアされ、フェー
ル判定フラグF1及び異常フラグF2がクリアされ、ポ
ンプ電流Ip(第9図参照)の作動を許容するポンプセ
ル作動フラグがクリアされる。In step a3, the starter flag is cleared, the fail determination flag F1 and the abnormality flag F2 are cleared, and the pump cell operation flag that allows operation of the pump current Ip (see FIG. 9) is cleared.
ステップa6ではリニアA/FセンサSの起動時期を規
制するセンサ起動タイマがまずリセットされ、その後ス
タートされる。In step a6, a sensor activation timer that regulates the activation timing of the linear A/F sensor S is first reset and then started.
ステップa8に達すると、ここではセンサ起動タイマの
カウント値が設定値θ(この値は起動時における空燃比
センサの確実な活性化を待つ、待ち時間に応じた値)を
上回ったか否かを判定する。When step a8 is reached, it is determined here whether the count value of the sensor activation timer has exceeded the set value θ (this value is a value corresponding to the waiting time for reliable activation of the air-fuel ratio sensor at the time of activation). do.
上回らない間はステップa17に進み、空燃比フィード
バック係数KPBを1に設定し5空燃比フイードバツク
を禁止処理し、燃料噴射量のオープンループ制御、即ち
、エンジン回転数N及び負荷A/Nに応じた燃料噴射量
を所定のマツプより算出し、その算出した算出燃料噴射
量FueQを所定のエリアに取り込み、ステップa1に
戻る。この処理以後の図示しない燃料噴射ルーチンでは
、これが所定クランク角での割込みタイミングに応じて
実行され、所定のオープンループ制御で決定された目標
空燃比を達成出来る燃料噴射が行われる。If the fuel injection amount is not exceeded, the process proceeds to step a17, where the air-fuel ratio feedback coefficient KPB is set to 1, the air-fuel ratio feedback is prohibited, and the fuel injection amount is controlled in an open-loop manner, that is, according to the engine speed N and the load A/N. The fuel injection amount is calculated from a predetermined map, the calculated fuel injection amount FueQ is taken into a predetermined area, and the process returns to step a1. After this process, a fuel injection routine (not shown) is executed in response to an interrupt timing at a predetermined crank angle, and fuel injection that can achieve the target air-fuel ratio determined by predetermined open-loop control is performed.
この後、ステップa2ではスタータフラグがゼロである
ことより、ステップa8に進み、センサ起動タイマがθ
をカウントし、カウント値がθを上回るとステップa9
に達する。ここではセンサ起動タイマがまだ作動中であ
ればそのカウント作動をそのときの値のまま停止させ、
ステップalOに進む。After this, in step a2, since the starter flag is zero, the process proceeds to step a8, and the sensor activation timer is set to θ.
is counted, and when the count value exceeds θ, step a9
reach. Here, if the sensor activation timer is still operating, its counting operation is stopped at the current value,
Proceed to step alO.
ここでは始め、ポンプセル作動フラグが1でないとステ
ップallに進み、ポンプセル21を作動し、フラグを
1とし、ポンプセル作動タイマをスタートさせ、同タイ
マのカウントが設定値E(空燃比センサの出力が安定す
るのを待つ待ち時間に相当する値)を上回ったか否かを
判定し、上回らない間はステップa17側のオープンル
ープ処理を継続し、上回ると、即ち待ち時間が経過しポ
ンプ電流■、が信頼性を持つと、ステップa15に進み
、ポンプセル作動タイマが作動中であればその時のカウ
ント値のままで、その作動を停止させ、ステップa20
に進む。At first, if the pump cell activation flag is not 1, the process proceeds to step all, in which the pump cell 21 is activated, the flag is set to 1, the pump cell activation timer is started, and the count of the timer reaches the set value E (the output of the air-fuel ratio sensor is stable). It is determined whether or not the value has exceeded the value (corresponding to the waiting time for waiting for If the pump cell operation timer is activated, the operation is stopped with the current count value unchanged, and step a20 is performed.
Proceed to.
ステップa20では空燃比センサSの異常判定をする。In step a20, it is determined whether the air-fuel ratio sensor S is abnormal.
まず、ステップa20としてのサブルーチン#1では、
第7図に示すように、空燃比信号Voutに基づくセン
サ異常の判定をする。ここでは、フェール判定フラグF
1が1とならない間で、フィードバック制御中のみ、ス
テップb3に進み、そうでないとメインルーチンへリタ
ーンする。。First, in subroutine #1 as step a20,
As shown in FIG. 7, sensor abnormality is determined based on the air-fuel ratio signal Vout. Here, the fail judgment flag F
Only during feedback control while 1 does not become 1, the process proceeds to step b3; otherwise, the process returns to the main routine. .
ステップb3,4ではメインルーチンで既に決定されて
いる現車両の運転状況に応じた目標空燃比A/Fの値の
読み込みを行い、リニアA/FセンサSより空燃比信号
Voutを読み込む。更に、所定の空燃比A/F算出マ
ツプ(図示せず)に沿って、空燃比信号Voutに応じ
た実空燃比を概算する。In steps b3 and b4, the value of the target air-fuel ratio A/F according to the driving situation of the current vehicle, which has already been determined in the main routine, is read, and the air-fuel ratio signal Vout from the linear A/F sensor S is read. Further, the actual air-fuel ratio according to the air-fuel ratio signal Vout is approximately calculated according to a predetermined air-fuel ratio A/F calculation map (not shown).
ステップb6では目標空燃比A/Fとセンサ検出の空燃
比との偏差ΔA/Fを算出する。そして、偏差ΔA/F
が故障判定である第二の判定値αを上回ったか否かを判
定し、上回っていないとステップb9に進み、上回って
いるとフェール判定フラグF1を1としてリターンする
。ステップb9では、偏差ΔA/Fが第一の判定値πを
上回ったか否かを判定し、上回った場合は異常フラグF
2を1としそうでないとそのままメインルーチンにリタ
ーンする。In step b6, a deviation ΔA/F between the target air-fuel ratio A/F and the air-fuel ratio detected by the sensor is calculated. And the deviation ΔA/F
It is determined whether or not exceeds the second determination value α which is a failure determination. If not, the process proceeds to step b9, and if it has exceeded, the fail determination flag F1 is set to 1 and the process returns. In step b9, it is determined whether the deviation ΔA/F exceeds the first judgment value π, and if it exceeds the abnormality flag F
If 2 is not set to 1, the process returns to the main routine.
このような異常判定の後、ステップa21に達する。こ
こでは、フェール判定フラグF1がゼロか否かを見て、
フェールであると直ちに空燃比フィードバック中断とシ
ステム停止処理ゾーンにあると見做す。即ち、ステップ
a16で、ポンプセル作動停止出力を駆動回路122を
介してポンプカット回路14に出力し、ポンプ電流1p
をカットし、ステップa、17に進む。After such an abnormality determination, step a21 is reached. Here, check whether the fail judgment flag F1 is zero or not,
If there is a failure, it is immediately assumed that the air-fuel ratio feedback is interrupted and the system is in the system stop processing zone. That is, in step a16, the pump cell operation stop output is output to the pump cut circuit 14 via the drive circuit 122, and the pump current 1p is output.
Cut and proceed to step a, 17.
他方、ステップa21でフェールでないとしてステップ
a22に達すると、ここでは現在の運転状態がフィード
バック条件を満たしているか否かを判定し、フィードバ
ック許容判定域に無い場合は、ステップa17のオープ
ンループ制御に進み、判定域にあるとステップa23に
達する。ここでは異常判定フラグF2が1か否かを判定
し、1の場合、空燃比フィードバック−時中断ゾーンに
あるとし、センサの回復を待つべくステップa17のオ
ープンループ制御に進む。他方、異常判定フラグF2が
ゼロでは空燃比フィードバックゾーンにあると判定し・
ステップa24に進む。On the other hand, when it is determined that there is no failure in step a21 and the process reaches step a22, it is determined here whether the current operating state satisfies the feedback condition, and if it is not within the feedback allowable determination area, the process proceeds to open loop control in step a17. , is in the determination range, the process reaches step a23. Here, it is determined whether the abnormality determination flag F2 is 1 or not, and if it is 1, it is determined that the air-fuel ratio feedback-time interruption zone exists, and the process proceeds to open loop control in step a17 to wait for the sensor to recover. On the other hand, if the abnormality determination flag F2 is zero, it is determined that the air-fuel ratio is in the feedback zone.
Proceed to step a24.
ステップa24では、空燃比信号Voutに基づき空燃
比算出(A/F)zの算出を(A/F)2=f(Vou
t)より行う。続いてメインルーチンで既に決定されて
いる現車両の運転状況に応じた目標空燃比A/Fの値の
読み込みを行い、この目標空燃比A/Fと実際の空燃比
(A/F)2との差を求め、しかも、これの前回値との
差ΔEも算出しておき、空燃比による燃料量補正係数K
FBの算出に入る。In step a24, the air-fuel ratio calculation (A/F)z is calculated based on the air-fuel ratio signal Vout as (A/F)2=f(Vou
t). Next, the value of the target air-fuel ratio A/F according to the driving situation of the current vehicle, which has already been determined in the main routine, is read, and this target air-fuel ratio A/F and the actual air-fuel ratio (A/F)2 are compared. , and also calculate the difference ΔE between this and the previous value, and calculate the fuel amount correction coefficient K based on the air-fuel ratio.
Enter FB calculation.
ここでは、差Δεのレベルに応じたゲインの比例項KA
(ε)と、三元触媒の応答遅れを防ぐためのオフセット
量Kpを算出し、更に、微分項としてのKO(Δε)、
積分項としてのΣKr (ε、−t+−a)を各々算出
し、これらの加減算により、KF!lを求める。Here, the proportional term KA of the gain according to the level of the difference Δε
(ε) and the offset amount Kp to prevent response delay of the three-way catalyst, and further calculate KO (Δε) as a differential term,
ΣKr (ε, -t+-a) as integral terms are calculated, and by addition and subtraction, KF! Find l.
この後ステップa19に進み、各補正係数KpIlyK
、及び基準燃料量Fにより、この時点での適正燃料供給
量FueQを算出し、ステップa1に戻る。After this, the process proceeds to step a19, and each correction coefficient KpIlyK
, and the reference fuel amount F, the appropriate fuel supply amount FueQ at this point is calculated, and the process returns to step a1.
このような処理で得られた値はメインルーチン中におけ
る所定クランク角信号の割込み時に行われる燃料噴射ル
ーチンで呼び出され、その値に応じた噴射時間だけ燃料
噴射ノズルNが駆動回路121を介して駆動され、所定
の空燃比を達成可能な燃料噴射がなされることとなる。The value obtained through such processing is called in the fuel injection routine performed when a predetermined crank angle signal interrupts in the main routine, and the fuel injection nozzle N is driven via the drive circuit 121 for an injection time corresponding to the value. This results in fuel injection that can achieve a predetermined air-fuel ratio.
(発明の効果)
以上のように、本発明は、異常処理手段が異常信号を受
けると、空燃比フィードバックのみを一旦停止し、オー
プンループ制御等を行ってセンサの復帰を待ち、故障信
号を受けるとセンサ作動を停止させ、空燃比フィードバ
ック制御を停止させ、これに代えたオープンループ制御
等の空燃比制御を実行可能であり、空燃比センサの異常
状態に適した空燃比制御を行うことが出来、空燃比のず
れによる排ガスの悪化、ドライバビリティ−の低下、ア
イドルの不安定化等の弊害を防止し、あるいは最小限に
押えることができる。(Effects of the Invention) As described above, in the present invention, when the abnormality processing means receives an abnormality signal, it temporarily stops only the air-fuel ratio feedback, performs open-loop control, waits for the sensor to recover, and receives the failure signal. It is possible to perform air-fuel ratio control such as open-loop control instead of this by stopping sensor operation and air-fuel ratio feedback control, and performing air-fuel ratio control suitable for abnormal conditions of the air-fuel ratio sensor. It is possible to prevent or minimize problems such as deterioration of exhaust gas, deterioration of drivability, and instability of idle due to air-fuel ratio deviation.
第1図は本発明の一実施例としての空燃比制御装置の概
略構成図、第2図は同上装置のコントローラの機能を表
すブロック図、第3図は同上装置内のセンサ駆動回路図
、第4図は同上装置の差分ΔA/Fに対する空燃比フィ
ードバック制御ゾーン説明図、第5図リニアA/Fセン
サの出力の経時変化線図、第6図(a )、(b )、
(c )および第7図は空燃比制御プログラムのフロー
チャート、第8図は従来の空燃比センサのセンサ素子部
分の構成の説明図、第9図は従来の空燃比センサの概略
構成図、第10図はポンプ電流と空燃比の関係を示す図
、第11図はポンプ電流の方向に基づくストイキオ信号
の特性を示す図である。
1・・・エンジン、11・・・排気系、12・・・コン
トローラ、N・・・燃料噴射ノズル、Vout・・・空
燃比信号、S・・・空燃比センサ、SC・・・センサ原
動回路、ΔA/F・・・差分。Fl・・・フェール判定
フラグ、F2・・・異常判定フラグ
S、ffi
胃
る 6 履
(a)
心7
【
嶌10
図
市47
叉
ノツチ
スト4〜オ
ノーン
A/FFIG. 1 is a schematic configuration diagram of an air-fuel ratio control device as an embodiment of the present invention, FIG. 2 is a block diagram showing the functions of the controller of the same device, FIG. 3 is a sensor drive circuit diagram in the same device, and FIG. Fig. 4 is an explanatory diagram of the air-fuel ratio feedback control zone for the difference ΔA/F of the same device, Fig. 5 is a graph of changes over time in the output of the linear A/F sensor, Fig. 6 (a), (b),
(c) and FIG. 7 are flowcharts of the air-fuel ratio control program, FIG. 8 is an explanatory diagram of the configuration of the sensor element portion of the conventional air-fuel ratio sensor, FIG. 9 is a schematic configuration diagram of the conventional air-fuel ratio sensor, and FIG. The figure shows the relationship between the pump current and the air-fuel ratio, and FIG. 11 shows the characteristics of the stoichiometry signal based on the direction of the pump current. DESCRIPTION OF SYMBOLS 1... Engine, 11... Exhaust system, 12... Controller, N... Fuel injection nozzle, Vout... Air-fuel ratio signal, S... Air-fuel ratio sensor, SC... Sensor driving circuit , ΔA/F...difference. Fl... Fail judgment flag, F2... Abnormality judgment flag S, ffi Gastric 6 Shoe (a) Heart 7 [Shim 10 Zuichi 47 Notchist 4 ~ Onone A/F
Claims (1)
を出力する空燃比センサと、上記空燃比信号と車両の運
転状態より決定された目標空燃比との差分である空燃比
ずれ量を算出するずれ量算出手段と、上記空燃比ずれ量
が第一の判定値を上回ると異常信号を出力する異常判定
手段と、上記空燃比ずれ量が上記第一の判定値より大き
な第二の判定値を上回ると故障信号を出力する故障判定
手段と、上記異常信号が出力された時、上記空燃比信号
に基づくフィードバック制御を行う手段による空燃比制
御を中断させ、上記故障信号が出力された時上記空燃比
信号に基づくフィードバック制御を行う手段による空燃
比制御を中断させると共にセンサ作動を停止させる異常
処理手段とを有した空燃比制御装置。An air-fuel ratio sensor that outputs an air-fuel ratio signal according to the oxygen concentration in exhaust gas after combustion of the air-fuel mixture, and an air-fuel ratio deviation amount that is the difference between the air-fuel ratio signal and a target air-fuel ratio determined from the vehicle operating condition. deviation amount calculation means for calculating, abnormality judgment means for outputting an abnormal signal when the air-fuel ratio deviation amount exceeds a first judgment value, and a second judgment in which the air-fuel ratio deviation amount is larger than the first judgment value. a failure determining means that outputs a failure signal when the abnormality signal exceeds a value; and when the abnormality signal is output, the air-fuel ratio control by the means for performing feedback control based on the air-fuel ratio signal is interrupted, and when the failure signal is output; An air-fuel ratio control device comprising abnormality processing means for interrupting air-fuel ratio control by the means for performing feedback control based on the air-fuel ratio signal and stopping sensor operation.
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2189227A JP2527083B2 (en) | 1990-07-17 | 1990-07-17 | Air-fuel ratio control device |
DE4122828A DE4122828C2 (en) | 1990-07-10 | 1991-07-10 | Air-fuel ratio control device for an internal combustion engine in a motor vehicle |
KR1019910011660A KR940004344B1 (en) | 1990-07-10 | 1991-07-10 | Air-fuel ratio controller |
US07/727,855 US5209206A (en) | 1990-07-10 | 1991-07-10 | Air-fuel ratio control system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2189227A JP2527083B2 (en) | 1990-07-17 | 1990-07-17 | Air-fuel ratio control device |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH0476244A true JPH0476244A (en) | 1992-03-11 |
JP2527083B2 JP2527083B2 (en) | 1996-08-21 |
Family
ID=16237714
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP2189227A Expired - Lifetime JP2527083B2 (en) | 1990-07-10 | 1990-07-17 | Air-fuel ratio control device |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP2527083B2 (en) |
-
1990
- 1990-07-17 JP JP2189227A patent/JP2527083B2/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
JP2527083B2 (en) | 1996-08-21 |
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