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EP0719918A1 - Process and device to control the air/fuel mixture in a spark ignited internal combustion engine - Google Patents

Process and device to control the air/fuel mixture in a spark ignited internal combustion engine Download PDF

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Publication number
EP0719918A1
EP0719918A1 EP95402920A EP95402920A EP0719918A1 EP 0719918 A1 EP0719918 A1 EP 0719918A1 EP 95402920 A EP95402920 A EP 95402920A EP 95402920 A EP95402920 A EP 95402920A EP 0719918 A1 EP0719918 A1 EP 0719918A1
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EP
European Patent Office
Prior art keywords
probe
richness
engine
carried out
exhaust line
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
Application number
EP95402920A
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German (de)
French (fr)
Other versions
EP0719918B1 (en
Inventor
Gaétan Monnier
Hervé Perrin
Richard Tilagone
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IFP Energies Nouvelles IFPEN
Original Assignee
IFP Energies Nouvelles IFPEN
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Publication of EP0719918A1 publication Critical patent/EP0719918A1/en
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Classifications

    • 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
    • F02D41/2406—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
    • F02D41/2425—Particular ways of programming the data
    • F02D41/2429—Methods of calibrating or learning
    • F02D41/2441—Methods of calibrating or learning characterised by the learning conditions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
    • F02D35/0015—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for using exhaust gas sensors
    • F02D35/0023—Controlling air supply
    • F02D35/0038—Controlling air supply by means of air pumps
    • 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
    • F02D41/2406—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
    • F02D41/2425—Particular ways of programming the data
    • F02D41/2429—Methods of calibrating or learning
    • F02D41/2451—Methods of calibrating or learning characterised by what is learned or calibrated
    • F02D41/2474—Characteristics of sensors
    • 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
    • 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
    • F02D41/2406—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
    • F02D41/2425—Particular ways of programming the data
    • F02D41/2429—Methods of calibrating or learning
    • F02D41/2432—Methods of calibration
    • 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
    • F02D41/2406—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
    • F02D41/2425—Particular ways of programming the data
    • F02D41/2429—Methods of calibrating or learning
    • F02D41/2451—Methods of calibrating or learning characterised by what is learned or calibrated
    • F02D41/2454—Learning of the air-fuel ratio control

Definitions

  • the present invention relates to the field of control and regulation of engines and more particularly of spark ignition engines operating in lean mixture.
  • One known way of limiting nitrogen oxide emissions consists in operating the engine at a minimum richness, close to the lean limit of engine stability.
  • This type of probe delivers a rather qualitative information allowing to know if the engine works in lean mixture (the output voltage of the probes then tends towards 0), in rich mixture (the output voltage of the probes tends towards 1 volt) or at the stoichiometry (output voltage of the probes, intermediate, of the order of 0.5 V).
  • proportional probes the output voltage of which varies in proportion to the richness of the mixture.
  • FIG. 1 appended shows that the response characteristic of an "aged" probe (dotted curve B) in particular undergoes a variation in slope vis- against an unaged probe (curve A).
  • the proportional probe is recalibrated around the richness 1, taking into account the information delivered by a Lambda probe. This process is for example described in document WO 94/19593.
  • a non-negligible drawback related to the recalibration, over a wider richness range, of probes placed in the exhaust is that the new calibration can only be carried out by dismantling the probe, that is to say during periods d immobilization of the vehicle.
  • the present invention provides a solution to the general problem of aging probes in the exhaust lines.
  • the present invention overcomes in particular the drawbacks mentioned above.
  • the subject of the invention is a method for controlling the richness of a positive-ignition engine operating in a lean mixture.
  • the method consists in performing an in situ registration (on vehicle) of at least one probe, at several points, corresponding to different richnesses, by means of a second probe.
  • the registration is carried out at at least two operating points; the first around a wealth equal to unity and the second around a zero wealth.
  • Zero wealth registration is performed when the engine is stopped.
  • this zero-rich readjustment is carried out by an additional air supply upstream of the measurement point or points.
  • the registration can be carried out at three operating points, the third point being chosen near wealth 1, preferably at a wealth somewhat greater than one.
  • Gas powered engines are particularly targeted by the invention.
  • the invention further relates to a device for regulating the richness of a positive-ignition engine operating in a lean mixture comprising at least a first richness measurement probe, placed on an exhaust line equipped with a catalyst, and intended to measure proportionally the richness of the fluid flowing in said exhaust line.
  • the device comprises a second probe, placed on said exhaust line, and intended to provide the information necessary for the registration of said first probe for a richness equal to unity during the operation of the engine.
  • This second measurement probe can be an all or nothing type probe.
  • the first probe is placed upstream of said catalyst while the second probe can be preferably placed downstream of the catalyst, to limit its aging.
  • the device according to the invention may comprise a pump placed on said exhaust line and intended to inject air upstream from said first probe.
  • the pump is an electric pump.
  • FIG 2 schematically appears an exhaust line 1 from a spark ignition engine 2.
  • a catalyst 3 type 2 or 3 three-way is placed on the exhaust line 1.
  • a probe Lambda 4 operating in all or nothing, is placed on said line 1 upstream or downstream of the catalyst 3.
  • This probe 4 provides binary information of the "rich mixture” or “lean mixture” type. It is used by the regulation system to maintain the richness at a value close to stoichiometry.
  • a second so-called proportional probe 5 is positioned on line 1, preferably between engine 2 and catalyst 3.
  • FIG. 3 differs from that just described by the additional presence of a pump 6 preferably placed between the motor 2 and the probe 5, intended to inject air just upstream of the probe 5.
  • the operation of the air pump 6 is not linked to that of the engine; an electric air pump will advantageously be chosen.
  • This figure shows the output voltage (U) of a proportional probe placed at the exhaust, as a function of the richness (R) of the mixture.
  • a resetting of the probe 5 is carried out on the vehicle at several points of different richnesses: a resetting with zero wealth (engine stopped), and a resetting with wealth equal to one (during engine operation).
  • An air pump such as 6 is more and more frequently fitted to engines having an air injection at the exhaust. Consequently, in this case, no element is to be added to the engine to make it operate according to the invention.
  • the registration according to the invention is therefore an automated step which does not require any specific human intervention or any specific immobilization of the vehicle.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
  • Ignition Installations For Internal Combustion Engines (AREA)

Abstract

The richness control method is used in an engine (2) having an exhaust pipe (1) which incorporates a two or three-way catalytic converter (3) with an all-or-nothing lambda probe (4) on the downstream side yielding binary information which signifies rich or lean mixture. A second probe (5) of proportional type is placed preferably between the engine and the converter. The control method involves recalibration of the second probe at several operating points corresp. to different mixture strengths. The recalibration of zero richness, corresp. to absence of combustion gas from the exhaust pipe, is preferably delayed for a time after the engine has been stopped.

Description

La présente invention concerne le domaine du contrôle et de la régulation de moteurs et plus particulièrement de moteurs à allumage commandé fonctionnant en mélange pauvre.The present invention relates to the field of control and regulation of engines and more particularly of spark ignition engines operating in lean mixture.

La sévérisation des normes dans la plupart des pays industrialisés impose notamment de minimiser les émissions d'oxyde d'azote.The tightening of standards in most industrialized countries means in particular to minimize nitrogen oxide emissions.

Une façon connue de limiter les émissions d'oxyde d'azote consiste à faire fonctionner le moteur à une richesse minimale, proche de la limite pauvre de stabilité du moteur.One known way of limiting nitrogen oxide emissions consists in operating the engine at a minimum richness, close to the lean limit of engine stability.

Dans le cas de moteurs traditionnels fonctionnant à la stoechiométrie, une ou plusieurs sondes "Lambda" sont placées sur la ligne d'échappement.In the case of traditional engines operating at stoichiometry, one or more "Lambda" probes are placed on the exhaust line.

Ce type de sonde délivre une information plutôt qualitative permettant de savoir si le moteur fonctionne en mélange pauvre (la tension de sortie des sondes tend alors vers 0), en mélange riche (la tension de sortie des sondes tend vers 1 volt) ou à la stoechiométrie (tension de sortie des sondes, intermédiaire, de l'ordre de 0,5 V).This type of probe delivers a rather qualitative information allowing to know if the engine works in lean mixture (the output voltage of the probes then tends towards 0), in rich mixture (the output voltage of the probes tends towards 1 volt) or at the stoichiometry (output voltage of the probes, intermediate, of the order of 0.5 V).

Sur certains moteurs, un autre type de sonde a déjà été utilisé afin d'améliorer les mesures : il s'agit de sondes dites proportionnelles dont la tension de sortie varie proportionnellement à la richesse du mélange.On certain engines, another type of probe has already been used to improve the measurements: these are called proportional probes, the output voltage of which varies in proportion to the richness of the mixture.

Ces deux types de sondes, traditionnellement placées près du moteur, sont susceptibles de voir leur surface active s'altérer avec le temps (encrassement, vieillissement thermique...).These two types of sensors, traditionally placed near the engine, are likely to see their active surface deteriorate over time (fouling, thermal aging, etc.).

En outre, dans le cas de moteurs fonctionnant au gaz, on peut trouver à l'échappement une proportion non négligeable d'hydrocarbures légers tels que le méthane, particulièrement difficile à oxyder.In addition, in the case of gas-powered engines, a significant proportion of light hydrocarbons such as methane can be found at the exhaust, which is particularly difficult to oxidize.

La combinaison de ces deux phénomènes peut à terme fausser l'information délivrée par les sondes de richesse.The combination of these two phenomena can ultimately distort the information delivered by the wealth probes.

Pour limiter ce problème il a été révélé dans le document SAE 932821, un agencement selon lequel une chambre de combustion spécifique est prévue en parallèle avec le moteur et une sonde de richesse est associée aux gaz issus de cette chambre qui, ne brûlant qu'une petite quantité de gaz naturel, n'enverra qu'une quantité réduite voire nulle de méthane vers la sonde. La durée de vie de cette sonde se trouve donc allongée au prix toutefois d'une modification non négligeable du moteur lui-même.To limit this problem, it was revealed in the document SAE 932821, an arrangement according to which a specific combustion chamber is provided in parallel with the engine and a richness probe is associated with the gases coming from this chamber which, burning only one small amount of natural gas, will only send a reduced or even zero amount of methane to the probe. The life of this probe is therefore extended at the cost, however, of a non-negligible modification of the motor itself.

Le phénomène de dérive observé sur une sonde proportionnelle équipant un moteur à gaz est illustré sur la figure 1 ci-annexée qui montre que la caractéristique de réponse d'une sonde "vieillie" (courbe B pointillée) subit notamment une variation de pente vis-à-vis d'une sonde non vieillie (courbe A).The drift phenomenon observed on a proportional probe fitted to a gas engine is illustrated in FIG. 1 appended which shows that the response characteristic of an "aged" probe (dotted curve B) in particular undergoes a variation in slope vis- against an unaged probe (curve A).

De façon habituelle, un recalage de la sonde proportionnelle autour de la richesse 1 est effectué, en tenant compte de l'information délivrée par une sonde Lambda. Ce procédé est par exemple décrit dans le document WO 94/19593.Usually, the proportional probe is recalibrated around the richness 1, taking into account the information delivered by a Lambda probe. This process is for example described in document WO 94/19593.

Cependant un tel recalage ne permet pas de retrouver la sensibilité de part et d'autre de la richesse 1, d'où un problème dans la précision et la fiabilité des mesures.However, such a registration does not make it possible to recover the sensitivity on either side of the richness 1, hence a problem in the precision and reliability of the measurements.

Un inconvénient non négligeable lié au recalage, sur une plage de richesse plus large, de sondes placées à l'échappement est que la nouvelle calibration ne peut être opérée qu'en démontant la sonde, c'est-à-dire pendant des périodes d'immobilisation du véhicule.A non-negligible drawback related to the recalibration, over a wider richness range, of probes placed in the exhaust is that the new calibration can only be carried out by dismantling the probe, that is to say during periods d immobilization of the vehicle.

La présente invention propose une solution au problème général du vieillissement des sondes dans les lignes d'échappement.The present invention provides a solution to the general problem of aging probes in the exhaust lines.

Elle permet en outre des mesures plus précises de la richesse puisque un plus grand nombre de points de recalage des mesures peut être obtenu selon l'invention.It also allows more precise measurements of the richness since a greater number of registration points of the measurements can be obtained according to the invention.

Ainsi, la présente invention permet de remédier notamment aux inconvénients cités ci-dessus.Thus, the present invention overcomes in particular the drawbacks mentioned above.

L'invention a pour objet un procédé de contrôle de la richesse d'un moteur à allumage commandé fonctionnant en mélange pauvre.The subject of the invention is a method for controlling the richness of a positive-ignition engine operating in a lean mixture.

Selon l'invention le procédé consiste à effectuer un recalage in situ (sur véhicule) d'au moins une sonde, en plusieurs points, correspondant à des richesses différentes, grâce à une deuxième sonde.According to the invention, the method consists in performing an in situ registration (on vehicle) of at least one probe, at several points, corresponding to different richnesses, by means of a second probe.

Préférentiellement, le recalage est réalisé en au moins deux points de fonctionnement ; le premier autour d'une richesse égale à l'unité et le deuxième autour d'une richesse nulle.Preferably, the registration is carried out at at least two operating points; the first around a wealth equal to unity and the second around a zero wealth.

Le recalage à richesse nulle est réalisé lorsque le moteur est à l'arrêt.Zero wealth registration is performed when the engine is stopped.

Avantageusement, ce recalage à richesse nulle s'effectue par un apport d'air supplémentaire en amont du ou des points de mesure.Advantageously, this zero-rich readjustment is carried out by an additional air supply upstream of the measurement point or points.

En outre, le recalage peut être opéré en trois points de fonctionnement, le troisième point étant choisi à proximité de la richesse 1, préférentiellement à une richesse quelque peu supérieure à un.In addition, the registration can be carried out at three operating points, the third point being chosen near wealth 1, preferably at a wealth somewhat greater than one.

Les moteurs alimentés au gaz sont particulièrement visés par l'invention.Gas powered engines are particularly targeted by the invention.

L'invention concerne en outre un dispositif de régulation de la richesse d'un moteur à allumage commandé fonctionnant en mélange pauvre comprenant au moins une première sonde de mesure de la richesse, placée sur une ligne d'échappement équipée d'un catalyseur, et destinée à mesurer de façon proportionnelle la richesse du fluide s'écoulant dans ladite ligne d'échappement.The invention further relates to a device for regulating the richness of a positive-ignition engine operating in a lean mixture comprising at least a first richness measurement probe, placed on an exhaust line equipped with a catalyst, and intended to measure proportionally the richness of the fluid flowing in said exhaust line.

Conformément à l'invention, le dispositif comprend une deuxième sonde, placée sur ladite ligne d'échappement, et destinée à fournir l'information nécessaire au recalage de ladite première sonde pour une richesse égale à l'unité pendant le fonctionnement du moteur.According to the invention, the device comprises a second probe, placed on said exhaust line, and intended to provide the information necessary for the registration of said first probe for a richness equal to unity during the operation of the engine.

Cette deuxième sonde de mesure peut être une sonde de type tout ou rien.This second measurement probe can be an all or nothing type probe.

Avantageusement, la première sonde est placée en amont dudit catalyseur tandis que la deuxième sonde peut être placée préférentiellement en aval du catalyseur, pour limiter son vieillissement.Advantageously, the first probe is placed upstream of said catalyst while the second probe can be preferably placed downstream of the catalyst, to limit its aging.

En outre, le dispositif selon l'invention peut comprendre une pompe placée sur ladite ligne d'échappement et destiné à injecter de l'air en amont de ladite première sonde.In addition, the device according to the invention may comprise a pump placed on said exhaust line and intended to inject air upstream from said first probe.

Sans sortir du cadre de l'invention, la pompe est une pompe électrique.Without departing from the scope of the invention, the pump is an electric pump.

D'autres caractéristiques, avantages et détails de l'invention apparaîtront plus clairement à la lecture de la description qui va suivre, faite à titre illustratif et nullement limitatif, en référence, aux dessins annexés sur lesquels :

  • La figure 2 est un schéma d'une ligne d'échappement selon un mode de réalisation de l'invention;
  • La figure 3 est un schéma d'une ligne d'échappement selon un autre mode de réalisation de l'invention; et
  • La figure 4 montre une courbe obtenue selon l'invention.
Other characteristics, advantages and details of the invention will appear more clearly on reading the description which follows, given by way of illustration and in no way limiting, with reference to the appended drawings in which:
  • Figure 2 is a diagram of an exhaust line according to an embodiment of the invention;
  • Figure 3 is a diagram of an exhaust line according to another embodiment of the invention; and
  • Figure 4 shows a curve obtained according to the invention.

Sur la figure 2 apparaît de façon schématique une ligne d'échappement 1 issue d'un moteur à allumage commandé 2. Un catalyseur 3 de type 2 ou 3 trois voies est placé sur la ligne d'échappement 1. De façon connue, une sonde Lambda 4, fonctionnant en tout ou rien, est placée sur ladite ligne 1 en amont ou en aval du catalyseur 3. Cette sonde 4 fournit une information binaire de type "mélange riche" ou "mélange pauvre". Elle est utilisée par le système de régulation pour maintenir la richesse à une valeur proche de la stoechiométrie.In Figure 2 schematically appears an exhaust line 1 from a spark ignition engine 2. A catalyst 3 type 2 or 3 three-way is placed on the exhaust line 1. In known manner, a probe Lambda 4, operating in all or nothing, is placed on said line 1 upstream or downstream of the catalyst 3. This probe 4 provides binary information of the "rich mixture" or "lean mixture" type. It is used by the regulation system to maintain the richness at a value close to stoichiometry.

Une deuxième sonde 5 dite proportionnelle est positionnée sur la ligne 1, de préférence entre le moteur 2 et le catalyseur 3.A second so-called proportional probe 5 is positioned on line 1, preferably between engine 2 and catalyst 3.

Le mode de réalisation de la figure 3 diffère de celui qui vient d'être décrit par la présence supplémentaire d'une pompe 6 placée préférentiellement entre le moteur 2 et la sonde 5, destinée à injecter de l'air juste en amont de la sonde 5.The embodiment of Figure 3 differs from that just described by the additional presence of a pump 6 preferably placed between the motor 2 and the probe 5, intended to inject air just upstream of the probe 5.

Si la ligne d'échappement 1 est déjà équipée d'une pompe à air 6 injectant, de façon connue, de l'air à l'échappement, alors cette pompe peut ici être en outre utilisée pour injecter spécifiquement de l'air juste en amont de la sonde 5. La ligne 7 en pointillée sur la figure 3 indique cette connexion supplémentaire.If the exhaust line 1 is already equipped with an air pump 6 injecting, in a known manner, air into the exhaust, then this pump can here also be used to specifically inject air just in upstream of the probe 5. The dotted line 7 in FIG. 3 indicates this additional connection.

Préférentiellement, le fonctionnement de la pompe à air 6 n'est pas lié à celui du moteur ; une pompe à air électrique sera avantageusement choisie.Preferably, the operation of the air pump 6 is not linked to that of the engine; an electric air pump will advantageously be chosen.

Le fonctionnement des éléments énoncés ci-dessus va maintenant être explicité, en relation avec la figure 4.The operation of the elements set out above will now be explained, in relation to FIG. 4.

Cette figure montre la tension de sortie (U) d'une sonde proportionnelle placée à l'échappement, en fonction de la richesse (R) du mélange.This figure shows the output voltage (U) of a proportional probe placed at the exhaust, as a function of the richness (R) of the mixture.

Selon l'invention, on réalise sur véhicule un recalage de la sonde 5 en plusieurs points de richesses différentes : un recalage à richesse nulle (moteur arrêté), et un recalage à richesse égale à un, (pendant le fonctionnement du moteur).According to the invention, a resetting of the probe 5 is carried out on the vehicle at several points of different richnesses: a resetting with zero wealth (engine stopped), and a resetting with wealth equal to one (during engine operation).

On peut effectuer plusieurs recalages autour de la richesse égale à 1 par exemple un recalage à R = 0,9 et un recalage à R = 1,1. Des recalages dans cette plage de mesure sont avantageux car de façon courante le système y répond linéairement.It is possible to carry out several readjustments around the richness equal to 1, for example a registration with R = 0.9 and a registration with R = 1.1. Recalibrations in this measurement range are advantageous because the system currently responds to them linearly.

Pour enrichir ou appauvrir temporairement le mélange, afin d'atteindre par exemple des richesses égales à 0,9 ou 1,1, il est possible de modifier le signal de commande du dispositif d'injection de gaz dans une proportion connue. En effet, par analogie aux dispositifs d'injection de carburant, dans certaines plages déterminées de fonctionnement, le débit injecté est directement proportionnel au temps d'injection. En contrôlant simplement le temps d'injection, on peut donc faire varier la richesse du mélange dans des proportions connues.To temporarily enrich or deplete the mixture, in order to reach, for example, richnesses equal to 0.9 or 1.1, it is possible to modify the control signal of the gas injection device in a known proportion. In fact, by analogy with fuel injection devices, in certain determined operating ranges, the flow injected is directly proportional to the injection time. By simply controlling the injection time, the richness of the mixture can therefore be varied in known proportions.

Dans la pratique on effectuera le recalage autour d'un troisième point de richesse supérieure à un, comme par exemple à R=1,1 afin de pouvoir recaler ultérieurement, par extrapolation, la sonde dans une plage de richesses supérieures à l'unité.In practice, the registration will be carried out around a third point of richness greater than one, such as for example at R = 1.1 in order to be able to readjust later, by extrapolation, the probe in a range of richnesses greater than unity.

Il est recommandé de faire varier le mélange à partir de conditions de fonctionnement stables par exemple à partir d'un fonctionnement à richesse égale à l'unité, au ralenti.It is recommended to vary the mixture on the basis of stable operating conditions, for example from an operation with richness equal to unity, at idle.

Pour obtenir un recalage à richesse nulle, correspondant à une absence de gaz de combustion dans le conduit d'échappement, il est préférable d'attendre un certain temps après l'arrêt du moteur.To obtain a zero-rich readjustment, corresponding to an absence of combustion gas in the exhaust duct, it is preferable to wait a certain time after the engine has stopped.

Il est possible selon l'invention de raccourcir cet arrêt prolongé en injectant de l'air frais juste en amont de la sonde 5 : La pompe 6 par exemple permet de réaliser cette fonction.It is possible according to the invention to shorten this prolonged stop by injecting fresh air just upstream of the probe 5: The pump 6 for example allows this function to be carried out.

Une pompe à air telle que 6 équipe de plus en plus fréquemment les moteurs ayant une injection d'air à l'échappement. Par conséquent, dans ce cas, aucun élément n'est à ajouter sur le moteur pour le faire fonctionner selon l'invention.An air pump such as 6 is more and more frequently fitted to engines having an air injection at the exhaust. Consequently, in this case, no element is to be added to the engine to make it operate according to the invention.

En outre une telle injection d'air permet de pallier au fait que des hydrocarbures sont susceptibles de se désorber des produits déposés à l'intérieur de la tubulure d'échappement.In addition, such an injection of air makes it possible to compensate for the fact that hydrocarbons are capable of being desorbed from the products deposited inside the exhaust manifold.

Le recalage selon l'invention est donc une étape automatisée qui ne nécessite aucune intervention humaine spécifique ni aucune immobilisation spécifique du véhicule.The registration according to the invention is therefore an automated step which does not require any specific human intervention or any specific immobilization of the vehicle.

Seule une attente supplémentaire peut être nécessaire, au démarrage du moteur.Only an additional wait may be necessary when starting the engine.

Claims (13)

Procédé de contrôle de la richesse d'un moteur (2) à allumage commandé fonctionnant en mélange pauvre, caractérisé en ce qu'il consiste à effectuer in situ (sur véhicule) un recalage d'au moins une sonde (5) en plusieurs points de fonctionnement, correspondant à des richesses différentes, grâce à une deuxième sonde (4).Method for controlling the richness of a spark-ignition engine (2) operating in a lean mixture, characterized in that it consists in performing in situ (on vehicle) a readjustment of at least one probe (5) at several points of operation, corresponding to different richnesses, thanks to a second probe (4). Procédé selon la revendication 1, caractérisé en ce que l'on réalise un recalage en au moins deux points de fonctionnement, le premier autour de la richesse 1 et le deuxième autour de la richesse nulle.Method according to claim 1, characterized in that a realignment is carried out at at least two operating points, the first around the wealth 1 and the second around the zero wealth. Procédé selon la revendication 2, caractérisé en ce que le recalage à richesse nulle est réalisé lorsque le moteur est à l'arrêt.Method according to claim 2, characterized in that the zero-rich readjustment is carried out when the engine is stopped. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que l'on réalise un recalage en trois points.Method according to any one of the preceding claims, characterized in that a three-point registration is carried out. Procédé selon la revendication 4, caractérisé en ce que l'on réalise un recalage autour d'un troisième point de fonctionnement correspondant à une richesse quelque peu supérieure à 1.Method according to claim 4, characterized in that a registration is carried out around a third operating point corresponding to a richness somewhat greater than 1. Procédé selon l'une quelconque des revendications 2 à 5, caractérisé en ce que le recalage autour de la richesse nulle s'effectue par un apport d'air supplémentaire en amont du ou des points de mesure.Method according to any one of claims 2 to 5, characterized in that the adjustment around the zero wealth is carried out by an additional air supply upstream of the measurement point (s). Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que ledit moteur est alimenté au gaz.Method according to any one of the preceding claims, characterized in that the said motor is supplied with gas. Dispositif de contrôle de richesse destiné à mettre en oeuvre le procédé selon l'une quelconque des revendications précédentes, comprenant au moins une première sonde (5), placée sur une ligne d'échappement (1) équipée d'un catalyseur (3), et destinée à mesurer de façon proportionnelle la richesse du fluide s'écoulant dans ladite ligne d'échappement, caractérisé en ce qu'il comprend en outre une deuxième sonde (4) placée sur la ligne d'échappement (1) et destinée à fournir l'information nécessaire au recalage de ladite première sonde (5) pour une richesse égale à l'unité, pendant le fonctionnement du moteur.Richness control device intended to implement the method according to any one of the preceding claims, comprising at least a first probe (5), placed on an exhaust line (1) equipped with a catalyst (3), and intended to measure proportionally the richness of the fluid flowing in said exhaust line, characterized in that it further comprises a second probe (4) placed on the exhaust line (1) and intended to supply the information necessary for the registration of said first probe (5) for a richness equal to unity, during the operation of the engine. Dispositif selon la revendication 8, caractérisé en ce que ladite deuxième sonde de mesure (4) est une sonde de type tout ou rien.Device according to claim 8, characterized in that said second measurement probe (4) is an all-or-nothing type probe. Dispositif selon la revendication 8 ou 9, caractérisé en ce que ladite première sonde (5) est placée en amont dudit catalyseur.Device according to claim 8 or 9, characterized in that said first probe (5) is placed upstream of said catalyst. Dispositif selon l'une quelconque des revendications 8 à 10, caractérisé en ce que ladite deuxième sonde (4) est placée en aval dudit catalyseur.Device according to any one of claims 8 to 10, characterized in that said second probe (4) is placed downstream of said catalyst. Dispositif selon l'une quelconque des revendications 8 à 11, caractérisé en ce qu'il comprend une pompe (6) destinée à injecter de l'air dans ladite ligne d'échappement (1) en amont de ladite première sonde (5).Device according to any one of claims 8 to 11, characterized in that it comprises a pump (6) intended to inject air into said exhaust line (1) upstream of said first probe (5). Dispositif selon la revendication 12, caractérisé en ce que la pompe (6) est une pompe électrique.Device according to claim 12, characterized in that the pump (6) is an electric pump.
EP95402920A 1994-12-29 1995-12-22 Process and device to control the air/fuel mixture in a spark ignited internal combustion engine Expired - Lifetime EP0719918B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9415898 1994-12-29
FR9415898A FR2728940A1 (en) 1994-12-29 1994-12-29 PROCESS AND DEVICE FOR CONTROLLING THE RICHNESS OF A CONTROLLED IGNITION ENGINE

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EP0719918A1 true EP0719918A1 (en) 1996-07-03
EP0719918B1 EP0719918B1 (en) 1998-09-02

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EP95402920A Expired - Lifetime EP0719918B1 (en) 1994-12-29 1995-12-22 Process and device to control the air/fuel mixture in a spark ignited internal combustion engine

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EP (1) EP0719918B1 (en)
AT (1) ATE170596T1 (en)
DE (1) DE69504468T2 (en)
ES (1) ES2121316T3 (en)
FR (1) FR2728940A1 (en)

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WO1999047915A1 (en) * 1998-03-13 1999-09-23 Fev Motorentechnik Gmbh Method for zero point stabilization of an exhaust-gas sensor and an arrangement for carrying out said method
EP1128181A2 (en) * 2000-02-23 2001-08-29 Heraeus Electro-Nite International N.V. Method for determining the contents of oxygen of a gas

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EP0878709A2 (en) * 1997-03-21 1998-11-18 NGK Spark Plug Co. Ltd. Method and apparatus for measuring NOx gas concentration
EP0878709A3 (en) * 1997-03-21 1999-04-28 NGK Spark Plug Co. Ltd. Method and apparatus for measuring NOx gas concentration
EP1074834A1 (en) 1997-03-21 2001-02-07 Ngk Spark Plug Co., Ltd Method and apparatus for measuring NOx gas concentration
US6375828B2 (en) 1997-03-21 2002-04-23 Ngk Spark Plug Co., Ltd. Methods and apparatus for measuring NOx gas concentration, for detecting exhaust gas concentration and for calibrating and controlling gas sensor
US6743352B2 (en) 1997-03-21 2004-06-01 Ngk Spark Plug Co., Ltd. Method and apparatus for correcting a gas sensor response for moisture in exhaust gas
US6923902B2 (en) 1997-03-21 2005-08-02 Ngk Spark Plug Co, Ltd. Methods and apparatus for measuring NOx gas concentration, for detecting exhaust gas concentration and for calibrating and controlling gas sensor
WO1999047915A1 (en) * 1998-03-13 1999-09-23 Fev Motorentechnik Gmbh Method for zero point stabilization of an exhaust-gas sensor and an arrangement for carrying out said method
EP1128181A2 (en) * 2000-02-23 2001-08-29 Heraeus Electro-Nite International N.V. Method for determining the contents of oxygen of a gas
EP1128181A3 (en) * 2000-02-23 2004-03-17 Heraeus Electro-Nite International N.V. Method for determining the contents of oxygen of a gas

Also Published As

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FR2728940A1 (en) 1996-07-05
FR2728940B1 (en) 1997-02-21
ATE170596T1 (en) 1998-09-15
DE69504468T2 (en) 1999-01-28
EP0719918B1 (en) 1998-09-02
DE69504468D1 (en) 1998-10-08
ES2121316T3 (en) 1998-11-16

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