EP0153493B1 - Mixture-measuring system for a combustion engine - Google Patents

Mixture-measuring system for a combustion engine Download PDF

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Publication number
EP0153493B1
EP0153493B1 EP84116261A EP84116261A EP0153493B1 EP 0153493 B1 EP0153493 B1 EP 0153493B1 EP 84116261 A EP84116261 A EP 84116261A EP 84116261 A EP84116261 A EP 84116261A EP 0153493 B1 EP0153493 B1 EP 0153493B1
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EP
European Patent Office
Prior art keywords
output
factor
metering system
correction value
mixture
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EP84116261A
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German (de)
French (fr)
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EP0153493A2 (en
EP0153493A3 (en
Inventor
Günter Braun
Werner Dipl.-Ing. Jundt
Norbert Dipl.-Ing. Miller
Jürgen Näger
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Robert Bosch GmbH
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Robert Bosch GmbH
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/26—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using computer, e.g. microprocessor
    • F02D41/266—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using computer, e.g. microprocessor the computer being backed-up or assisted by another circuit, e.g. analogue
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1477—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the regulation circuit or part of it,(e.g. comparator, PI regulator, output)
    • F02D41/1481—Using a delaying circuit
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio
    • F02D41/1456—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio with sensor output signal being linear or quasi-linear with the concentration of oxygen

Definitions

  • the invention is based on a mixture metering system for an internal combustion engine with a digital computing unit according to the preamble of the main claim.
  • DE-OS 3 124 676 shows a mixture metering system with the essential features of the preamble.
  • the mixture metering system according to the invention for an internal combustion engine with a digital arithmetic unit with the features of the main claim makes it possible to provide an optimal mixture of this output signal to the internal combustion engine irrespective of the time of the change in the output variable of a signal generating means in relation to the timed, delayed signal processing.
  • a low pollutant concentration in the exhaust gas can be ensured. It has proven to be advantageous to influence the mixture metering as a function of at least the delay time and / or the timing of the digital computing unit.
  • FIG. 1 shows a rough overview of a mixture metering system with a microcomputer
  • FIG. 2 shows a block diagram of the mixture metering system according to the invention
  • FIG. 3 shows a time diagram to explain the functioning of the mixture metering system in FIG. 2.
  • the following exemplary embodiments are described in connection with a fuel injection system.
  • the mixture metering system in connection with the correction function according to the invention is however independent of the method of mixture metering, so that the invention z. B. can also be used in conjunction with carburetor systems.
  • the representation of the mixture metering system according to the invention on the basis of a block diagram (FIG. 2) does not limit a practical embodiment to a single possibility of implementation.
  • the implementation by means of a freely programmable computer is therefore problem-free because the invention is clearly recognizable as such and therefore does not pose any problems for a person skilled in the field of electronic mixture metering systems.
  • FIG. 1 shows a schematic overview of a computer-controlled system with the most important components.
  • 11 denotes an arithmetic logic unit which is coupled via a data control and address bus 12 to a memory 13 and to an input / output unit 14.
  • this unit 14 receives various input variables I K and outputs various output variables O K , for example an injection duration for the amount of fuel to be metered or a signal for the actuator in one Air bypass of a carburetor system.
  • FIG. 2 an embodiment of the invention is shown as a block diagram.
  • the probe signal evaluation unit 21 and the control device 23 are connected to a correction stage 24, which has a corresponding correction function and to which an output unit 25 is connected.
  • the output unit 25 and the probe signal evaluation unit 21 are supplied in particular with different time cycles of a time cycle unit 26.
  • the probe signal evaluation unit 21 is provided with setpoint information U ⁇ 5 , which represents setpoint information for the air-force ratio to be metered to the internal combustion engine.
  • the mixture formation unit 27 influences an internal combustion engine 29, the exhaust gas 30 expelled by the internal combustion engine washing around the exhaust gas probe 15 and influencing its output variable U ⁇ l , so that the control loop for mixture formation is closed.
  • the function of the components of the probe signal evaluation unit 21, time stage 22, control unit 23 as well as correction stage 24 and output unit 25 can also be realized with the aid of a correspondingly programmed microcomputer 31, indicated by dashed lines in FIG.
  • the pilot control by means of the pilot control unit 28 and the timing unit 26 can also be integrated in the microcomputer 31.
  • a low output signal level corresponds to a lean and a high output signal level to a rich air-fuel mixture.
  • This exhaust gas probe output variable is compared in the probe signal evaluation unit 21 with the target value U ⁇ s and sampled with a counting frequency, the period of which is identified by T.
  • the corresponding output signal U SA of the probe signal evaluation unit 21 is plotted in FIG. 3b.
  • This signal possibly delayed by a desired time, reaches control unit 23, on the one hand, directly to correction stage 24 and, on the other hand, via time stage 22, which essentially serves to shift the average air-fuel ratio.
  • the output signals of the control device 23 via the output unit 25 influence the mixture formation unit 27, for example multiplicatively by a factor F R. Since the time period T 2 between two successive outputs of the output unit 25 generally assumes different values compared to the sampling rate T 1 ' , in particular larger values, for various programming reasons, as shown in FIGS. 3d and e, time delays between the actual switching process of the probe and the forwarding of this switching operation by the output unit 25. This can result in more or less short-term shifts in the mean value of the output signal (factor F R ), so that under certain circumstances a considerable deviation from the air ratio required for a possible catalytic exhaust gas aftertreatment occurs.
  • Correction stage 24 is required for this purpose, the mode of operation of which is explained in more detail below.
  • Exemplary embodiments of the invention have been described using a lambda-controlled mixture metering system for an internal combustion engine. Idle charge control, exhaust gas recirculation control, knock control, extreme value control and the like can be mentioned as further control methods for the mixture composition of an internal combustion engine, in which the invention can be used.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Testing Of Engines (AREA)

Abstract

The invention is directed to a mixture metering arrangement for an internal combustion engine with a digital data processor, particularly a microcomputer, the signal processing pattern of which is governed by clock pulses, and with a signal generating means which delivers analog output signals. The signal generating means is responsive to operating parameters of the internal combustion engine and is an exhaust gas sensor responsive to the air ratio Lambda. The exhaust gas sensor is used in a closed-loop control system to influence the air-fuel ratio and changes its output quantity at the air ratio of Lambda=1. In this arrangement, a correcting stage corrects the influence of a delay time (tv) connected with the clocked signal processing on the mixture formation. The delay occurs in the transmission of the change in the output of the sensor. Two methods are indicated for the mode of operation of the correcting stage by means of which a mean value shift of the quantity (FR) influencing the mixture formation is avoided and the concentration of toxic substances in the exhaust gases is minimized. Flowcharts are disclosed to realize the invention by means of a suitably programmed microcomputer.

Description

Stand der TechnikState of the art

Die Erfindung geht aus von einem Gemischzumeßsystem für eine Brennkraftmaschine mit einer digitalen Recheneinheit nach der Gattung des Hauptanspruchs.The invention is based on a mixture metering system for an internal combustion engine with a digital computing unit according to the preamble of the main claim.

Bekannt ist aus der US-A-4 337 745 bei einem Lambda-Regelungssystem eine Korrekturfunktion vorzusehen. Diese Korrekturfunktion korrigiert die unterschiedliche Trägheit des Lambda-Sensors in den beiden möglichen Schaltrichtungen von Fett nach Mager und umgekehrt, weil ohne diese Kompensation eine nicht erwünschte Lambda-Verschiebung auftreten würde (siehe hierzu Figur 6b der US-A-4 337 745).It is known from US-A-4,337,745 to provide a correction function for a lambda control system. This correction function corrects the different inertia of the lambda sensor in the two possible switching directions from rich to lean and vice versa, because without this compensation an undesired lambda shift would occur (see FIG. 6b of US Pat. No. 4,337,745).

Des weiteren zeigt die DE-OS 3 124 676 ein Gemischzumeßsystem mit den wesentlichen Merkmalen des Oberbegriffs. Obwohl dieses bekannte System in der Praxis zufriedenstellend arbeitet, hat es sich jedoch gezeigt, daß aufgrund der hohen Anforderungen an die Schadstofffreiheit des Abgases weitere Verbesserungen möglich und erforderlich sind.Furthermore, DE-OS 3 124 676 shows a mixture metering system with the essential features of the preamble. Although this known system works satisfactorily in practice, it has been shown, however, that further improvements are possible and necessary due to the high demands on the emission-free nature of the exhaust gas.

Vorteile der ErfindungAdvantages of the invention

Das erfindungsgemäße Gemischzumeßsystem für eine Brennkraftmaschine mit einer digitalen Recheneinheit mit den Merkmalen des Hauptanspruchs ermöglicht es dagegen, unabhängig vom Zeitpunkt der Änderung der Ausgangsgröße eines Signalerzeugungsmittels in Relation zur zeitgetakteten, verzögerten Signalverarbeitung dieses Ausgangssignal der Brennkraftmaschine ein optimales Gemisch zur Verfügung zu stellen. Insbesondere durch eine Korrektur des Einflusses einer verzögerten Weitergabe der Änderung der Ausgangsgröße der Sonde kann für eine geringe Schadstoffkonzentration im Abgas gesorgt werden. Es erweist sich als vorteilhaft, die Gemischzumessung in Abhängigkeit von zumindest der Verzögerungszeit und/oder des Zeittaktes der digitalen Recheneinheit korrigierend zu beeinflussen.The mixture metering system according to the invention for an internal combustion engine with a digital arithmetic unit with the features of the main claim, on the other hand, makes it possible to provide an optimal mixture of this output signal to the internal combustion engine irrespective of the time of the change in the output variable of a signal generating means in relation to the timed, delayed signal processing. In particular, by correcting the influence of a delayed transmission of the change in the output variable of the probe, a low pollutant concentration in the exhaust gas can be ensured. It has proven to be advantageous to influence the mixture metering as a function of at least the delay time and / or the timing of the digital computing unit.

Weitere Vorteile der Erfindung ergeben sich in Verbindung mit den Unteransprüchen aus der nachfolgenden Beschreibung der Ausführungsbeispiele.Further advantages of the invention result in connection with the subclaims from the following description of the exemplary embodiments.

Zeichnungdrawing

Es zeigen Figur 1 eine grobe Übersicht über ein Gemischzumeßsystem mit einem Mikrocomputer, Figur 2 ein Blockschaltbild des erfindungsgemäßen Gemischzumeßsystems und Figur 3 ein Zeitdigramm zur Erläuterung der Funktionsweise des Gemischzumeßsystems in der Figur 2.FIG. 1 shows a rough overview of a mixture metering system with a microcomputer, FIG. 2 shows a block diagram of the mixture metering system according to the invention, and FIG. 3 shows a time diagram to explain the functioning of the mixture metering system in FIG. 2.

Beschreibung derdescription of AusführungsbeispieleEmbodiments

Die folgenden Ausführungsbeispiele werden im Zusammenhang mit einer Kraftstoffeinspritzanlage beschrieben. Das Gemischzumeßsystem in Verbindung mit der erfindungsgemäßen Korrekturfunktion ist jedoch unabhängig von der Methode der Gemischzumessung, so daß die Erfindung z. B. auch in Verbindung mit Vergaseranlagen einsetzbar ist. Auch die Darstellung des erfindungsgemäßen Gemischzumeßsystems anhand eines Blockschaltbildes (Figur 2) begrenzt eine praktische Ausführungsform nicht auf eine einzige Möglichkeit der Realisierung. Die Realisierung mittels eines frei programmierbaren Rechners ist deshalb problemlos, weil die Erfindung als solche klar erkennbar ist und somit für einen Fachmann auf dem Gebiet der elektronischen Gemischzumeßsysteme keinerlei Probleme liefert.The following exemplary embodiments are described in connection with a fuel injection system. The mixture metering system in connection with the correction function according to the invention is however independent of the method of mixture metering, so that the invention z. B. can also be used in conjunction with carburetor systems. The representation of the mixture metering system according to the invention on the basis of a block diagram (FIG. 2) does not limit a practical embodiment to a single possibility of implementation. The implementation by means of a freely programmable computer is therefore problem-free because the invention is clearly recognizable as such and therefore does not pose any problems for a person skilled in the field of electronic mixture metering systems.

Figur 1 zeigt in schematischer Weise eine Übersicht über ein rechnergesteuertes System mit den wesentlichsten Komponenten. Mit 11 ist ein Rechenwerk bezeichnet, das über einen Daten-Steuer- und Adressbus 12 mit einem Speicher 13 sowie mit einer Ein-Ausgabe-Einheit 14 gekoppelt ist. Diese Einheit 14 erhält neben einem Signal von einem Signalerzeugungsmittel, insbesondere einer Sonde 15, insbesondere einer Lambda-Sonde, verschiedene Eingangsgrößen IK zugeführt und gibt verschiedene Ausgangsgrößen OK ab, beispielsweise eine Einspritzzeitdauer fur die zuzumessende Kraftstoffmenge oder ein Signal für den Steller in einem Luftbypass einer Vergaseranlage.Figure 1 shows a schematic overview of a computer-controlled system with the most important components. 11 denotes an arithmetic logic unit which is coupled via a data control and address bus 12 to a memory 13 and to an input / output unit 14. In addition to a signal from a signal generating means, in particular a probe 15, in particular a lambda probe, this unit 14 receives various input variables I K and outputs various output variables O K , for example an injection duration for the amount of fuel to be metered or a signal for the actuator in one Air bypass of a carburetor system.

In Figur 2 ist ein Ausführungsbeispiel der Erfindung als Blockschaltbild dargestellt. Die mit 15 bezeichnete Sonde, im vorliegenden Beispiel als Abgassonde ausgebildet, liefert eine Ausgangsgröße UÄI an eine Sondensignalauswerteeinheit 21, die ihrerseits über eine Zeitstufe 22 mit einer vorzugsweise als PI-Regler ausgebildeten Regeleinrichtung 23 verbunden ist. Weiterhin sind die Sondensignalauswerteeinheit 21 sowie die Regeleinrichtung 23 mit einer eine entsprechende Korrekturfunktion liefenden Korrekturstufe 24, an die eine Ausgabeeinheit 25 angeschlossen ist, verbunden. Der Ausgabeeinheit 25 sowie der Sondensignalauswerteeinheit 21 werden insbesondere unterschiedliche Zeittakte einer Zeittakteinheit 26 zugeführt. Daneben liegt an der Sondensignalauswerteeinheit 21 eine Sollwertinformation UÄ5 an, die eine Sollwertinformation für das der Brennkraftmaschine zuzumessende Luft-Kraft-Verhältnis darstellt. Einer Gemischbildungseinheit 27, werden die Signale der Ausgabeeinheit 25 (Falktor FR) sowie einer Vorsteuerungseinheit 28 zugeführt, wobei die Vorsteuerungseinheit 28 Eingangsgrößen über Betriebsparameter der Brennkraftmaschine wie die Drehzahl, Last oder Temperatur und ähnliches verarbeitet. Die Gemischbildungseinheit 27 beeinflußt eine Brennkraftmaschine 29, wobei das von der Brennkraftmaschine ausgestoßene Abgas 30 die Abgassonde 15 umspült und deren Ausgangsgröße Uλl beeinflußt, so daß der Regelkreis für die Gemischbildung geschlossen ist. Es versteht sich, daß die Funktion der Komponenten Sondensignalauswerteeinheit 21, Zeitstufe 22, Regeleinheit 23 sowie Korrekturstufe 24 und Ausgabeeinheit 25 ebenso mit Hilfe eines entsprechend programmierten, in der Figur 2 gestrichelt angedeuteten Mikrocomputer 31 realisiert werden können. Auch die Vorsteuerung mittels der Vorsteuerungseinheit 28 sowie die Zeittakteinheit 26 kann im Mikrocomputer 31 integriert sein.In Figure 2, an embodiment of the invention is shown as a block diagram. The probe denoted by 15, in the present example designed as an exhaust gas probe, supplies an output variable U.sub.II to a probe signal evaluation unit 21, which in turn is connected via a time stage 22 to a control device 23 which is preferably designed as a PI controller. Furthermore, the probe signal evaluation unit 21 and the control device 23 are connected to a correction stage 24, which has a corresponding correction function and to which an output unit 25 is connected. The output unit 25 and the probe signal evaluation unit 21 are supplied in particular with different time cycles of a time cycle unit 26. In addition, the probe signal evaluation unit 21 is provided with setpoint information U Ä5 , which represents setpoint information for the air-force ratio to be metered to the internal combustion engine. A mixture formation unit 27, the signals the output unit 25 (Falktor F R ) and a pilot control unit 28, wherein the pilot unit 28 processes input variables via operating parameters of the internal combustion engine such as the speed, load or temperature and the like. The mixture formation unit 27 influences an internal combustion engine 29, the exhaust gas 30 expelled by the internal combustion engine washing around the exhaust gas probe 15 and influencing its output variable U λl , so that the control loop for mixture formation is closed. It goes without saying that the function of the components of the probe signal evaluation unit 21, time stage 22, control unit 23 as well as correction stage 24 and output unit 25 can also be realized with the aid of a correspondingly programmed microcomputer 31, indicated by dashed lines in FIG. The pilot control by means of the pilot control unit 28 and the timing unit 26 can also be integrated in the microcomputer 31.

Bis auf die Blöcke Zeittakteinheit 26 sowie Korrekturstufe 24 und Ausgabeeinheit 25 ist diese Anordnung hinreichend bekannt, so daß ihre Funktionsweise nicht näher erläutert werden muß. Wichtig für den Kern der Erfindung ist nun die Tatsache, daß aufgrund der digitalen, zeitgetakteten Datenverarbeitung Verzögerungszeiten in der Weitergabe der Änderung der vorzugsweise analogen Ausgangsgröße U),1 an die Gemischbildungseinheit 27 zur überlagerten Beeinflussung des Kraftstoff-Luft-Verhältnisses auftreten. Zur Erläuterung der hiermit verbundenen Problematik dienen die in Figur 3 dargestellten Zeitdiagramme, wobei in Figur 3a das vorzugsweise analoge Ausgangssignal UÄI der Sonde 15 für den Sonderfall dargestellt ist, daß die Sonde 15 als (Lambda = 1) -Sonde ausgebildet ist. Dabei entspricht ein niedriger Ausgangssignalpegel einem mageren und ein hoher Ausgangssignalpegel einem fetten Luft-Kraftstoff-Gemisch. Diese Abgassonden-Ausgangsgröße wird in der Sondensignalauswerteeinheit 21 mit dem Sollwert UÄs verglichen und mit einer Zählfrequenz, deren Periodendauer mit T, gekennzeichnet ist, abgetastet. Das entsprechende Ausgangssignal USA der Sondensignalauswerteeinheit 21 ist in der Figur 3b aufgetragen. Dieses Signal gelangt eventuell um eine gewünschte Zeit verzögert zum einen direkt auf die Korrekturstufe 24 und zum anderen über die Zeitstufe 22, die im wesentlichen zu einer Verschiebung des mittleren Luft-Kraftstoff-Verhältnisses dient, zur Regeleinheit 23.Except for the blocks timing unit 26 and correction stage 24 and output unit 25, this arrangement is well known, so that its mode of operation need not be explained in more detail. What is important for the essence of the invention is the fact that, due to the digital, time-clocked data processing, delay times occur in the transfer of the change in the preferably analog output variable U), 1 to the mixture formation unit 27 for superimposed influencing of the fuel-air ratio. The time diagrams shown in FIG. 3 serve to explain the problems associated with this, FIG. 3a showing the preferably analog output signal U.sub.II of the probe 15 for the special case that the probe 15 is designed as a (lambda = 1) probe. A low output signal level corresponds to a lean and a high output signal level to a rich air-fuel mixture. This exhaust gas probe output variable is compared in the probe signal evaluation unit 21 with the target value U Äs and sampled with a counting frequency, the period of which is identified by T. The corresponding output signal U SA of the probe signal evaluation unit 21 is plotted in FIG. 3b. This signal, possibly delayed by a desired time, reaches control unit 23, on the one hand, directly to correction stage 24 and, on the other hand, via time stage 22, which essentially serves to shift the average air-fuel ratio.

Das Ausgangsignal UPI der Regeleinrichtung 23, das im vorliegenden Ausführungsbeispiel für einen konstanten Ausgangspegel der Abgassonde 15 integrales Verhalten und beim Wechsel des Ausgangspegels proportionales Verhalten aufweist, ist in Figur 3c aufgetragen.The output signal U PI of the control device 23, which in the present exemplary embodiment has integral behavior for a constant output level of the exhaust gas probe 15 and behavior which is proportional when the output level changes, is plotted in FIG. 3c.

Es gilt nun als Stand der Technik, daß die Ausgangssignale der Regeleinrichtung 23 über die Ausgabeeinheit 25 die Gemischbildungseinheit 27 beispielsweise multiplikativ mit einem Faktor FR beeinflussen. Da aus verschiedenen programmtechnischen Gründen die Zeitdauer T2 zwischen zwei aufeinanderfolgenden Ausgaben der Ausgabeeinheit 25 im allgemeinen unterschiedliche Werte im Vergleich zur Abtastrate T1' nämlich insbesondere größere Werte annimmt, können, wie in Figur 3d und e dargestellt, Zeitverzögerungen zwischen dem tatsächlichen Schaltvorgang der Sonde und der Weitergabe dieses Schaltvorganges durch die Ausgabeeinheit 25 auftreten. Hieraus können mehr oder minder kurzzeitige Mittelwertschiebungen des Ausgabesignals (Faktor FR) resultieren, so daß unter Umständen eine erhebliche Abweichung vom für eine eventuelle katalytische Abgasnachbehandlung erforderlichen Luftverhältnis auftritt.It is now considered state of the art that the output signals of the control device 23 via the output unit 25 influence the mixture formation unit 27, for example multiplicatively by a factor F R. Since the time period T 2 between two successive outputs of the output unit 25 generally assumes different values compared to the sampling rate T 1 ' , in particular larger values, for various programming reasons, as shown in FIGS. 3d and e, time delays between the actual switching process of the probe and the forwarding of this switching operation by the output unit 25. This can result in more or less short-term shifts in the mean value of the output signal (factor F R ), so that under certain circumstances a considerable deviation from the air ratio required for a possible catalytic exhaust gas aftertreatment occurs.

Zur Vermeidung dieser Nachteile und einer daraus resultierenden hohen Schadstoffkonzentration, die auch nicht durch einen Katalysator zu reduzieren ist, ist es erforderlich, die aufgrund dieser verzögerten Ausgabe des Faktors FR entstandene Abweichung möglichst rasch durch einen Eingriff zu korrigieren. Hierzu ist die Korrekturstufe 24 erforderlich, deren Funktionsweise im folgenden näher erläutert wird.In order to avoid these disadvantages and a resulting high concentration of pollutants, which cannot be reduced by a catalyst either, it is necessary to correct the deviation resulting from this delayed output of the factor F R as quickly as possible by an intervention. Correction stage 24 is required for this purpose, the mode of operation of which is explained in more detail below.

In Figur 3d ist den von der Korrekturstufe 24 über die Ausgabeeinheit 25 im Zeittakt T2 ausgegebene Faktor FR aufgetragen. Die aufgrund der unterschiedlichen Verarbeitungszeiten im Mikrocomputer auftretende Verzögerungszeit in der Weitergabe der Änderung der Ausgangsgröße der Abgassonde 15 ist mit tv gekennzeichnet. Der Signalverlauf, der ohne Einwirken der Ausgabeeinheit 25 und der Korrekturstufe 24 auftreten würde, ist gestrichelt gekennzeichnet. Aus dieser Figur ist zu entnehmen, daß aufgrund der verzögerten Ausgabe eine Mittelwertverschiebung des Faktors FR auftritt, da sich das Flächenverhältnis für Flächen oberhalb und unterhalb der gestrichelten, bei Fr = 1 eingetragenen Linie ändert. Dies führt zumindestens kurzzeitig zu einer Änderung des der Brennkraftmaschine zugeführten Luft-Kraftstoff-Verhältnisses. Zur Vermeidung dieser Mittelwertverschiebung werden nun zwei Möglichkeiten vorgeschlagen. In beiden Fällen wird die Verzögerungszeit, die sich aus der Differenz zwischen der Änderung der Ausgangsgröße der Abgassonde und der tatsächlichen Ausgabe (siehe Figur 3b in Verbindung mit 3d) ergibt, in Relation zur Taktzeit T2 gesetzt. Zur Bestimmung eines Korrekturwertes nach der ersten Methode ist eine Multiplikation dieses Wertes mit der Größe A Ausgang, die sich, natürlich geeignet normiert, aus der Differenz der neuen Ausgangsgröße und der alten Ausgangsgröße beispielsweise der Sondensignalauswerteeinheit 21 ergibt, vorgesehen. Im vorliegenden Spezialfall ergibt sich das Verhältnis von Verzögerungszeit zur Taktzeit T2 zu etwa 0,75 und der Wert A Ausgang aus Figur 2b zu (-1), so daß sich der Korrekturwert auf (-0,75) willkürliche Einheiten (bezogen auf die Skala der Figur 3c) beläuft. Beim nächsten Schaltvorgang der Sonde liegen die gleichen Verhältnisse, allerdings mit umgekehrten Vorzeichen für Ausgang vor, so daß sich hier ein Korrekturwert von (+0,75) willkürlichen Einheiten ergibt. Der Korrekturwert wird somit nach der Rechenvorschrift:

  • Korrekturwert = (Verzögerungszeit tv/Taktzeit T2) · A Ausgang mit A Ausgang = neue Ausgangsgröße - alte Ausggangsgröße berechnet. Um diesen Korrekturwert wird de jeweilige Faktor FR modifiziert (siehe Ablaufplan Seite 8), wobei möglicherweise notwendige Normierungsfaktoren für A Ausgang nicht berücksichtigt wurden. Eine Normierung ist im allgemeinen dazu notwendig, die Ausgangsgröße A Ausgang in Einheiten des Faktors FR umzurechnen.
The factor F R output by the correction stage 24 via the output unit 25 in the time cycle T 2 is plotted in FIG. 3d. The delay time occurring in the transmission of the change in the output variable of the exhaust gas probe 15 due to the different processing times in the microcomputer is identified by t v . The signal curve, which would occur without the action of the output unit 25 and the correction stage 24, is indicated by dashed lines. From this figure it can be seen that due to the delayed output an average shift of the factor F R occurs since the area ratio for areas above and below the dashed line entered at F r = 1 changes. This leads at least for a short time to a change in the air-fuel ratio supplied to the internal combustion engine. To avoid this shift in the mean value, two options are now proposed. In both cases, the delay time, which results from the difference between the change in the output variable of the exhaust gas probe and the actual output (see FIG. 3b in conjunction with 3d), is set in relation to the cycle time T 2 . To determine a correction value according to the first method, a multiplication of this value by the size A output is provided, which, of course, suitably normalized, results from the difference between the new output size and the old output size, for example of the probe signal evaluation unit 21. In this special case, the ratio of delay time to Cycle time T 2 to about 0.75 and the value A output from FIG. 2b to (-1), so that the correction value amounts to (-0.75) arbitrary units (based on the scale of FIG. 3c). The next time the probe is switched, the same conditions are present, but with the opposite sign for the output, so that there is a correction value of (+0.75) arbitrary units. The correction value is thus based on the calculation rule:
  • Correction value = (delay time t v / cycle time T 2 ) · A output with A output = new output variable - old output variable calculated. The respective factor F R is modified by this correction value (see flowchart on page 8), whereby any necessary standardization factors for A output were not taken into account. Standardization is generally necessary to convert the output variable A output into units of factor F R.

Die zweite Methode geht von dem Konzept aus, eine Änderung des Ausgangssignals jeweils mit einer Verzugszeit von mindestens einem Zeittakt T2 abzuarbeiten. Während dieser Verzugszeit, die durchaus auch mehrere, beispielsweise n Taktzeiten T2 umfassen kann, wird unter Vernachlässigung von Normierungsfaktoren eine, nach der Formel:

  • neue Ausgabegröße = alte Ausgabegröße + (Verzögerungszeit tv/Taktzeit T2) · Δ Ausgang
  • mit A Ausgang = neue Ausgangsgröße - alte Ausggangsgröße berechnete Größe als Faktor FR ausgegeben (siehe Ablaufplan Seite 9). Der zeitliche Verlauf des Faktors FR ergibt sich in entsprechender Weise wie beim ersten Ausführungsbeispiel (Figur 3d) und ist in Figur 3e aufgetragen.
The second method is based on the concept of processing a change in the output signal with a delay time of at least one time cycle T 2 . During this delay time, which can also include several, for example n cycle times T 2 , neglecting normalization factors, one becomes, according to the formula:
  • new output variable = old output variable + (delay time t v / cycle time T 2 ) · Δ output
  • with A output = new output variable - old output variable, calculated quantity output as factor F R (see flowchart on page 9). The time course of the factor F R results in a manner corresponding to that in the first exemplary embodiment (FIG. 3d) and is plotted in FIG. 3e.

Obwohl das Ausführungsbeispiel aus Gründen der Anschaulichkeit blockschaltbildmäßig dargestellt wurde, ist auch an eine Realisierung mittels eines entsprechend programmierten Mikrocomputer gedacht. Zur Erläuterung der entsprechenden Programmstruktur sind im folgenden zwei Ablaufpläne, entsprechend den beiden Methoden zur Ermittlung des Korrekturwertes, dargestellt. Diese Ablaufpläne sprechen für sich selbst, so daß neben den obigen Ausführungen keine weiteren Erläuterungen notwendig sind.

Figure imgb0001
Figure imgb0002
Although the exemplary embodiment has been shown in block diagram form for reasons of clarity, it is also intended to be implemented using a suitably programmed microcomputer. To explain the corresponding program structure, two flow charts are shown below, corresponding to the two methods for determining the correction value. These flow charts speak for themselves, so that no further explanations are necessary in addition to the above.
Figure imgb0001
Figure imgb0002

Ausführungsbeispiele der Erfindung wurden anhand eines Lambda-geregelten Gemischzumeßsystems für eine Brennkraftmaschine beschrieben. Als weitere Regelverfahren für die Gemischzusammensetzung einer Brennkraftmaschine, bei denen die Erfindung einsetzbar ist, können beispielsweise die Leerlauffüllungsregelung, Regelung der Abgasrückführung, Klopfregelung, Extremwertregelung und ähnliches genannt werden.Exemplary embodiments of the invention have been described using a lambda-controlled mixture metering system for an internal combustion engine. Idle charge control, exhaust gas recirculation control, knock control, extreme value control and the like can be mentioned as further control methods for the mixture composition of an internal combustion engine, in which the invention can be used.

Claims (10)

1. Mixture metering system for a combustion engine having a digital processing unit, in particular a microcomputer, whose signal processing sequence is bound to clock pulses and having a signal generating means which outputs, in particular, analog output signals and is sensitive to operating parameters of the combustion engine, in particular to an exhaust gas probe sensitive to the air ratio lambda, which signal generating means is used in a closed-loop control having a correction function to influence the air-fuel ratio and in particular changes its output variable where air ratio lambda = 1, characterized in that the closed-loop control with the correction function (24) corrects the influence of a delay time (tv) connected to the clock-pulsed signal processing in the forwarding of the change of the output value of the signal generating means for the carburetion, and thereby determines a correction value as a function of at least the recorded delay time (tv).
2. Mixture metering system according to claim 1, characterized in that the correction function (24) determines a correction value as a function of a pulse time (T2) of the digital processing unit.
3. Mixture metering system according to one of the preceding claims, characterized in that the correction function (24) determines a correction value as a function of the change of the output variable of two successive output variables (A output) of the signal generating means.
4. Mixture metering system according to at least one of the preceding claims, characterized in that the correction function (24) determines a correction value according to the formula:
correction value = (delay time tv/pulse time T2) x A output x N
where output = nth output variable - (n-1)th output variable and
N normalization factor.
5. Mixture metering system according to at least one of the preceding claims, characterized in that after a change of the output variable, for determining a factor (FR), factors (FR) lying temporally more than at least one pulse time (T2) behind are processed by the correction function (24).
6. Mixture metering system according to claim 5, characterized in that the correction function (24) during this period of at least one pulse time (T2) determines a factor (FR) changed by the correction value.
7. Mixture metering system according to claim 6, characterized in that the factor (FR) for the carburetion is formed in accordance with the formula:
nth factor = (n-m)th factor + correction value with m = 1, 2, 3, ...
8. Mixture metering system according to at least one of claims 1 to 4, characterized in that after a change of the output variable of the signal generation means, for determining the factor (FR), a factor (FR) lying temporally behind by less than one pulse time (T2) is processed by the correction function (24).
9. Mixture metering system according to claim 8, characterized in that the factor (FR) for the carburetion is formed according to the formula:
nth factor nth factor + correction value.
10. Mixture metering system according to at least one of the preceding claims, characterized in that the factor (FR) is only corrected by a correction value when the output variable of the signal generation means changes.
EP84116261A 1984-02-18 1984-12-22 Mixture-measuring system for a combustion engine Expired EP0153493B1 (en)

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AT84116261T ATE41813T1 (en) 1984-02-18 1984-12-22 MIXTURE METERING SYSTEM FOR AN ENGINE.

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DE19843405916 DE3405916A1 (en) 1984-02-18 1984-02-18 MIXING METERING SYSTEM FOR AN INTERNAL COMBUSTION ENGINE
DE3405916 1984-02-18

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DE3825749A1 (en) * 1988-07-29 1990-03-08 Daimler Benz Ag METHOD FOR ADAPTIVE CONTROL OF AN COMBUSTION ENGINE AND / OR ANOTHER DRIVE COMPONENT OF A MOTOR VEHICLE
US8450931B2 (en) 2005-05-10 2013-05-28 Dow Corning Corporation Process for minimizing electromigration in an electronic device
JP4286880B2 (en) * 2007-04-25 2009-07-01 本田技研工業株式会社 Program for searching for control parameters

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FR2423806A1 (en) * 1977-05-26 1979-11-16 Anvar REGULATION PROCESS WITH REFERENCE MODEL AND REGULATOR IMPLEMENTING THIS PROCESS
US4307694A (en) * 1980-06-02 1981-12-29 Ford Motor Company Digital feedback system
CA1174334A (en) * 1980-06-17 1984-09-11 William G. Rado Statistical air fuel ratio control
FR2485641A1 (en) * 1980-06-26 1981-12-31 Renault METHOD AND APPARATUS FOR ELECTRONIC IGNITION CONTROL FOR INTERNAL COMBUSTION ENGINE
US4337745A (en) * 1980-09-26 1982-07-06 General Motors Corporation Closed loop air/fuel ratio control system with oxygen sensor signal compensation
US4345194A (en) * 1980-12-01 1982-08-17 The United States Of America As Represented By The United States Department Of Energy Control system to reduce the effects of friction in drive trains of continuous-path-positioning systems
DE3046863A1 (en) * 1980-12-12 1982-07-22 Robert Bosch Gmbh, 7000 Stuttgart ELECTRONICALLY CONTROLLED FUEL MEASURING SYSTEM FOR AN INTERNAL COMBUSTION ENGINE
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JPS5813140A (en) * 1981-07-17 1983-01-25 Nissan Motor Co Ltd Electronic engine control device with external adjustment function
JPS59194053A (en) * 1983-04-18 1984-11-02 Toyota Motor Corp Method and device of air-fuel ratio control for internal- combustion engine

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EP0153493A2 (en) 1985-09-04
EP0153493A3 (en) 1986-12-03
US4689746A (en) 1987-08-25
DE3477502D1 (en) 1989-05-03
DE3405916A1 (en) 1985-08-22
JPS60190628A (en) 1985-09-28

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