WO2010066954A1 - Method and device for diagnosing the operation of an oxygen probe - Google Patents
Method and device for diagnosing the operation of an oxygen probe Download PDFInfo
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- WO2010066954A1 WO2010066954A1 PCT/FR2008/052250 FR2008052250W WO2010066954A1 WO 2010066954 A1 WO2010066954 A1 WO 2010066954A1 FR 2008052250 W FR2008052250 W FR 2008052250W WO 2010066954 A1 WO2010066954 A1 WO 2010066954A1
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- probe
- heating circuit
- heating
- during
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/4067—Means for heating or controlling the temperature of the solid electrolyte
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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
- F02D41/02—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
- F02D41/1493—Details
- F02D41/1494—Control of sensor heater
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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
- F02D41/02—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
- F02D41/1493—Details
- F02D41/1495—Detection of abnormalities in the air/fuel ratio feedback system
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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
- F02D41/20—Output circuits, e.g. for controlling currents in command coils
- F02D2041/202—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit
- F02D2041/2058—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit using information of the actual current value
Definitions
- the invention relates to a method and a device for diagnosing the operation of an oxygen sensor. It relates in particular to a method and a device for diagnosing the operation of the heating circuit of such a probe.
- one or more oxygen probes also called Lambda probes, are placed in its exhaust line.
- the output voltage of this probe is a function of the amount of oxygen present in the exhaust gas.
- the amount of pollutants emitted by the engine is a function of the richness of the fuel mixture. This wealth is regulated by the signal provided by the oxygen sensor, it is important that this information is as reliable as possible as quickly as possible.
- an oxygen sensor To deliver a signal truly representative of the richness of the fuel mixture, an oxygen sensor must operate within a predetermined temperature range. This temperature range can be between 650 and 850 °. During a cold start, the heat generated by the exhaust gas is not enough to heat the oxygen sensor to work properly.
- the oxygen sensors are therefore provided with an auxiliary heating circuit disposed near the sensing element of the probe and for heating the probe so that it functions well in this temperature range.
- pollutants such as nitrogen oxides (NOx), unburned hydrocarbons (HC) and carbon oxides (CO)
- this method does not allow a diagnosis of the heating circuit of the probe. If the heating circuit is defective by implementing the method described in US 2003-0178016, the value of the pulse width modulation will be modified to compensate for this defect and there will be no indication of the malfunction of the circuit. heater. This modification may even only partially compensate for the malfunction present and may result in an increase in the amount of pollutants emitted cold, and poor regulation of the temperature of the sensing element of the probe.
- An object of the present invention is to overcome the disadvantages of the prior art.
- the invention provides a robust and reliable device and method for diagnosing the operating state of the heating circuit of an oxygen sensor.
- the invention relates to a method for diagnosing the operating state of the heating circuit of an oxygen sensor, characterized in that it comprises:
- the heating circuit of the faulty probe is declared if the number of elementary windows for which the operation of the heating circuit of the probe has been declared faulty is greater than a threshold, during step d) the heating circuit of the faulty probe is declared if, for all the elementary windows, the operation of the heating circuit has been declared to be faulty, during the preliminary diagnostic step the operation of the heating circuit of the probe is declared to be faulty if the value current average is below the threshold, the method comprises a step of delaying and stabilizing the temperature of the heating resistor of the heating circuit of the probe, this step being prior to step a),
- the invention also relates to a device for diagnosing the operating state of the heating circuit of an oxygen sensor, the device comprising an electronic control unit connected to the heating circuit of the probe, characterized in that the device comprises in besides means for:
- FIG. 1 schematically represents a combustion engine internal equipped with two oxygen probes
- FIG. 2 is a partial electrical diagram of an oxygen sensor connected to an electronic control unit
- FIG. 3 is a flow chart of the various steps of the method according to the invention.
- the spark ignition internal combustion engine 6 comprises a plurality of injectors 8 injecting fuel into each of the cylinders 10 of the engine 6.
- the injectors 8 receive control signals of one unit electronic control unit (ECU) 16 through connections 14.
- I 1 ECU receives signals from the oxygen probes 18 and 20 arranged in an exhaust duct 28, respectively upstream and downstream of a catalytic converter 22, through the connections 24 and 26.
- the output signal of each probe 18 and 20 contains information on the residual oxygen content of the exhaust gases and also on the momentary ratio of air and fuel of the mixture sucked by the engine 6.
- the high and low levels of this signal correspond to the respective richnesses greater than and less than the stoichiometric ratio (wealth 1).
- the engine 6 further comprises in its intake line a butterfly valve 12 for controlling the amount of air admitted into the engine.
- L 1 UC E also receives other information (temperature of the intake air, inlet pressure, temperature of the engine cooling water, engine speed, etc.) from other sensors not shown in the figure. 1 via connections 32 to 36.
- FIG. 2 is an internal circuit diagram of one of the probes 18 or 20 of FIG. 1 and of its connection with I 1 ECU.
- Each probe 18, 20 comprises a heating circuit Cc comprising a heating resistor Rc and a signal circuit.
- sensor Cs having an internal resistance Rs of the sensing element of the element of the probe 1 or 20.
- the heating circuit Cc of the probe is connected to the ECU by the connections a and b and the circuit delivering the signal of the probe is connected to the motor by the connections c and d.
- L 1 UC E calculates the intensity of the current flowing through the heating circuit Cc from the voltage it measures at the terminals of this circuit Cc and from an internal resistor (not shown in the figure) implanted in an assembly said to current mirror.
- the invention proposes a method and a device for diagnosing the heating circuit of the oxygen sensor.
- step 50 I 1 UC E initializes all the variables used to perform the diagnosis of the heating circuit Cc. Then, in step 52 I 1 UC E verifies that the conditions for carrying out the test are met:
- the engine has at least reached a predetermined speed range, for example between 750 and 800 revolutions per minute,
- the temperature of the coolant is greater than a predetermined value, for example greater than -7 °,
- the electrical diagnoses of the probe 18 or 20 have detected no defects on the heating circuit Cc or on the signal circuit Cs; the other sensors, for example the temperature sensor of the coolant, making it possible to carry out the diagnosis are not declared defective.
- a delay timer is started by I 1 UC E before the actual diagnosis is made. This delay makes it possible to wait for the stabilization of the temperature of the heating resistor Rc. Indeed, the value of the heating resistor Rc varies depending on the temperature which causes significant variations in the value of the heating current passing through the heating circuit Cc and which can therefore affect the result of the diagnosis.
- I 1 UC E verifies that the diagnosis of the heating circuit can be performed. This step can be performed by checking the logical state of a booM authorization boolean. If the diagnosis is not allowed, step 52 is performed again. Otherwise, in step 56 I 1 UC E verifies that the heating command has been activated by checking the logic state of a heating activation boolean bool2. If the heating control has not been activated, step 54 is performed again. In the opposite case to step 58, I 1 UC E calculates an average value Imoy of the current flowing through the heating circuit Cc during a basic acquisition window.
- An elementary acquisition window, or elementary window, is here understood to mean a predetermined duration during which the average value of the current Imoy is calculated continuously by I 1 ECU. As long as the duration of the elementary window has not elapsed, the steps 56 and 58 are realized. L 1 UC E verifies that the duration of the basic acquisition window has elapsed in step 60. In step 62, when a basic acquisition window has elapsed, I 1 UC E compares the average value of the current heating Imoy having passed through the heating circuit Cc during a basic window to a threshold value S1 and declares this window fault if the average value Imoy of the current is below the threshold S1.
- step 64 I 1 UC E counts the number of elementary windows Nf elapsed and compares it with a threshold value Nmax. If the number of acquisition window elapsed is less than Nmax, step 54 is performed again. If this is not the case, at step 66 I 1 UC E declares the heating circuit faulty if all the basic acquisition windows have been declared as faulty. According to another alternative embodiment L 1 UC E can declare the circuit to be faulty if only certain elementary windows have been declared faulty. When a fault has been detected by the diagnosis according to the invention, it can be signaled to the driver of the vehicle, for example by lighting a warning light on the dashboard.
- the number of elementary detection windows is configurable. It is thus possible to adapt the diagnostic process to different types of oxygen sensors.
Abstract
Method of diagnosing the state of operation of the heating circuit of an oxygen probe, characterized in that it comprises: a) a step (58) of calculating the average value (Imoy) of the heating current of the probe over a predetermined period, called an elementary window; b) a step (62) of comparing this average value (Imoy) with a threshold value (S1) in order to carry out a preliminary diagnosis of the operation of the heating circuit (Cc) of the probe during this elementary window; c) a step (56,58,60) during which steps a) and b) are repeated a predetermined number (Nmin) of times; and d) a step (66) corresponding to the definitive diagnosis of the heating circuit of the probe according to the result of the preliminary diagnoses.
Description
PROCEDE ET DISPOSITIF DE DIAGNOSTIC DU FONCTIONNNEMENT D1UNE SONDE A OXYGENE.METHOD AND DEVICE FOR DIAGNOSIS OF FONCTIONNNEMENT 1 AN OXYGEN SENSOR.
L'invention concerne un procédé et un dispositif de diagnostic du fonctionnement d'une sonde à oxygène. Elle concerne en particulier un procédé et un dispositif de diagnostic du fonctionnement du circuit de chauffage d'une telle sonde.The invention relates to a method and a device for diagnosing the operation of an oxygen sensor. It relates in particular to a method and a device for diagnosing the operation of the heating circuit of such a probe.
Afin de déterminer la richesse du mélange gazeux introduit dans les cylindres d'un moteur à combustion interne installé dans un véhicule automobile, on place dans sa ligne d'échappement une ou plusieurs sondes à oxygène encore appelées sonde Lambda. La tension de sortie de cette sonde est fonction de la quantité d'oxygène présent dans les gaz d'échappement.In order to determine the richness of the gaseous mixture introduced into the cylinders of an internal combustion engine installed in a motor vehicle, one or more oxygen probes, also called Lambda probes, are placed in its exhaust line. The output voltage of this probe is a function of the amount of oxygen present in the exhaust gas.
La quantité de polluants émis par le moteur est fonction de la richesse du mélange carburé. Cette richesse étant régulée grâce au signal fourni par la sonde à oxygène, il est important que cette information soit la plus fiable possible le plus rapidement possible.The amount of pollutants emitted by the engine is a function of the richness of the fuel mixture. This wealth is regulated by the signal provided by the oxygen sensor, it is important that this information is as reliable as possible as quickly as possible.
Pour délivrer un signal véritablement représentatif de la richesse du mélange carburé, une sonde à oxygène doit fonctionner dans une gamme de température prédéterminée. Cette gamme de températures peut être comprise entre 650 et 850°. Lors d'un démarrage à froid, la chaleur dégagée par les gaz d'échappement ne suffit pas à chauffer la sonde à oxygène pour qu'elle fonctionne correctement. Les sondes à oxygène sont donc pourvues d'un circuit de chauffage auxiliaire disposé à proximité de l'élément sensible de la sonde et destiné à chauffer la sonde pour qu'elle fonctionne bien dans cette gamme de températures.
Pour répondre aux normes internationales concernant les émissions de substances polluantes, tels les oxydes d'azote (NOx), les hydrocarbures imbrûlés (HC) et les oxydes de carbone (CO), il est utile de surveiller le fonctionnement du circuit de chauffage de la sonde.To deliver a signal truly representative of the richness of the fuel mixture, an oxygen sensor must operate within a predetermined temperature range. This temperature range can be between 650 and 850 °. During a cold start, the heat generated by the exhaust gas is not enough to heat the oxygen sensor to work properly. The oxygen sensors are therefore provided with an auxiliary heating circuit disposed near the sensing element of the probe and for heating the probe so that it functions well in this temperature range. To meet international standards for emissions of pollutants, such as nitrogen oxides (NOx), unburned hydrocarbons (HC) and carbon oxides (CO), it is useful to monitor the operation of the heating circuit of the probe.
Le document US 2003-0178016 décrit un procédé de régulation de la température de chauffage d'une sonde à oxygène. Ce document propose de réguler le courant traversant la résistance de chauffage de cette sonde en utilisant une modulation de largeur d'impulsion.Document US 2003-0178016 describes a method of regulating the heating temperature of an oxygen probe. This document proposes to regulate the current flowing through the heating resistor of this probe by using a pulse width modulation.
Toutefois, ce procédé ne permet pas d'effectuer un diagnostic du circuit de chauffage de la sonde. Si le circuit de chauffage est défectueux en mettant en œuvre le procédé décrit dans US 2003-0178016, la valeur de la modulation de largeur d'impulsion sera modifiée pour compenser ce défaut et il n'y aura aucune indication sur le disfonctionnement du circuit de chauffage. Cette modification peut même ne compenser que partiellement le disfonctionnement présent et peut aboutir à une augmentation de la quantité de polluants émis à froid, et à une mauvaise régulation de la température de l'élément sensible de la sonde.However, this method does not allow a diagnosis of the heating circuit of the probe. If the heating circuit is defective by implementing the method described in US 2003-0178016, the value of the pulse width modulation will be modified to compensate for this defect and there will be no indication of the malfunction of the circuit. heater. This modification may even only partially compensate for the malfunction present and may result in an increase in the amount of pollutants emitted cold, and poor regulation of the temperature of the sensing element of the probe.
Un but de la présente invention est de remédier aux inconvénients de l'art antérieur.An object of the present invention is to overcome the disadvantages of the prior art.
L'invention propose un dispositif et un procédé robustes et fiables permettant de diagnostiquer l'état de fonctionnement du circuit de chauffage d'une sonde à oxygène.
L'invention concerne un procédé de diagnostic de l'état de fonctionnement du circuit de chauffage d'une sonde à oxygène caractérisé en ce qu'il comporte :The invention provides a robust and reliable device and method for diagnosing the operating state of the heating circuit of an oxygen sensor. The invention relates to a method for diagnosing the operating state of the heating circuit of an oxygen sensor, characterized in that it comprises:
- a) une étape de calcul de la valeur moyenne du courant de chauffage de la sonde durant une durée prédéterminée appelée fenêtre élémentaire, - b) une étape de comparaison de cette valeur moyenne à une valeur de seuil pour effectuer un diagnostic préliminaire du fonctionnement du circuit de chauffage de la sonde durant cette fenêtre élémentaire, c) une étape au cours de laquelle les étapes a et b sont répétées un nombre prédéterminé de fois, d) une étape de diagnostic définitif du circuit de chauffage de la sonde en fonction du résultat des diagnostics préliminaires.a) a step of calculating the average value of the heating current of the probe during a predetermined duration called elementary window, b) a step of comparing this average value with a threshold value to perform a preliminary diagnosis of the operation of the heating circuit of the probe during this elementary window, c) a step during which steps a and b are repeated a predetermined number of times, d) a definitive diagnostic step of the heating circuit of the probe according to the result preliminary diagnoses.
Selon d'autres caractéristiques du procédé:According to other characteristics of the process:
- durant l'étape d) on déclare le circuit de chauffage de la sonde défaillant si le nombre de fenêtres élémentaires pour lesquels le fonctionnement du circuit de chauffage de la sonde a été déclaré défaillant est supérieur à un seuil, durant l'étape d) on déclare le circuit de chauffage de la sonde défaillant si pour toutes les fenêtres élémentaires le fonctionnement du circuit de chauffage a été déclaré défaillant, lors de l'étape de diagnostic préliminaire le fonctionnement du circuit de chauffage de la sonde est déclaré défaillant si la valeur moyenne du courant est inférieure au seuil, le procédé comporte une étape de temporisation et de stabilisation de la température de la résistance de chauffage du circuit de chauffage de la sonde, cette étape étant préalable à l'étape a),during step d), the heating circuit of the faulty probe is declared if the number of elementary windows for which the operation of the heating circuit of the probe has been declared faulty is greater than a threshold, during step d) the heating circuit of the faulty probe is declared if, for all the elementary windows, the operation of the heating circuit has been declared to be faulty, during the preliminary diagnostic step the operation of the heating circuit of the probe is declared to be faulty if the value current average is below the threshold, the method comprises a step of delaying and stabilizing the temperature of the heating resistor of the heating circuit of the probe, this step being prior to step a),
- la défaillance du circuit de chauffage de la sonde est signalée au conducteur.
L'invention concerne également un dispositif de diagnostic de l'état de fonctionnement du circuit de chauffage d'une sonde à oxygène, le dispositif comportant une unité électronique de commande reliée au circuit de chauffage de la sonde caractérisé en ce que le dispositif comporte en outre des moyens pour:- the failure of the heating circuit of the probe is signaled to the driver. The invention also relates to a device for diagnosing the operating state of the heating circuit of an oxygen sensor, the device comprising an electronic control unit connected to the heating circuit of the probe, characterized in that the device comprises in besides means for:
- calculer de la valeur moyenne du courant de chauffage de la sonde durant une durée prédéterminée, appelée fenêtre élémentaire,calculating the average value of the heating current of the probe during a predetermined duration, called the elementary window,
- comparer cette valeur moyenne à une valeur de seuil pour effectuer un diagnostic préliminaire du fonctionnement du circuit de chauffage de la sonde durant cette fenêtre élémentaire,comparing this average value with a threshold value to perform a preliminary diagnosis of the operation of the heating circuit of the probe during this elementary window,
- diagnostiquer le fonctionnement du circuit de chauffage de la sonde en fonction du résultat des diagnostics préliminaires.- diagnose the operation of the heating circuit of the probe according to the result of the preliminary diagnoses.
D'autres avantages et caractéristiques de la présente invention apparaîtront à l'examen de la description détaillée d'un mode de réalisation de l'invention, nullement limitatif, et des dessins annexés, sur lesquels: la figure 1 représente schématiquement un moteur à combustion interne équipé de deux sondes à oxygène,Other advantages and features of the present invention will appear on examining the detailed description of an embodiment of the invention, in no way limiting, and the accompanying drawings, in which: FIG. 1 schematically represents a combustion engine internal equipped with two oxygen probes,
- la figure 2 est un schéma électrique partiel d'une sonde à oxygène connectée à une unité électronique de commande,FIG. 2 is a partial electrical diagram of an oxygen sensor connected to an electronic control unit,
- la figure 3 est un ordinogramme des différentes étapes du procédé selon l'invention.- Figure 3 is a flow chart of the various steps of the method according to the invention.
On se réfère à présent à la figure 1. Le moteur à combustion interne 6 à allumage commandé comporte une pluralité d'injecteurs 8 injectant du carburant dans chacun des cylindres 10 du moteur 6. Les injecteurs 8 reçoivent des signaux de commande d'une unité de commande électronique (U. C. E.) 16 par l'intermédiaire de connexions 14. Pour commander le temps d'ouverture des injecteurs 8, I1U. C. E. reçoit des signaux en provenance des
sondes à oxygène 18 et 20 disposées dans un conduit d'échappement 28, respectivement en amont et en aval d'un convertisseur catalytique 22, par les connexions 24 et 26. Le signal de sortie de chaque sonde 18 et 20 contient une information sur la teneur en oxygène résiduel des gaz d'échappement et également sur le rapport momentané d'air et de carburant du mélange aspiré par le moteur 6. Les nivaux haut et bas de ce signal correspondent à des richesses respectivement supérieure et inférieure au rapport stoechiométrique (richesse 1 ). Le moteur 6 comporte en outre dans sa ligne d'admission une vanne papillon 12 destinée à contrôler la quantité d'air admis dans le moteur.Referring now to FIG. 1, the spark ignition internal combustion engine 6 comprises a plurality of injectors 8 injecting fuel into each of the cylinders 10 of the engine 6. The injectors 8 receive control signals of one unit electronic control unit (ECU) 16 through connections 14. To control the opening time of the injectors 8, I 1 ECU receives signals from the oxygen probes 18 and 20 arranged in an exhaust duct 28, respectively upstream and downstream of a catalytic converter 22, through the connections 24 and 26. The output signal of each probe 18 and 20 contains information on the residual oxygen content of the exhaust gases and also on the momentary ratio of air and fuel of the mixture sucked by the engine 6. The high and low levels of this signal correspond to the respective richnesses greater than and less than the stoichiometric ratio (wealth 1). The engine 6 further comprises in its intake line a butterfly valve 12 for controlling the amount of air admitted into the engine.
L1U. C. E reçoit également d'autres informations (température de l'air admis, pression à l'admission, température de l'eau de refroidissement moteur, régime moteur ...) en provenance d'autres capteurs non représentés sur la figure 1 via les connexion 32 à 36.L 1 UC E also receives other information (temperature of the intake air, inlet pressure, temperature of the engine cooling water, engine speed, etc.) from other sensors not shown in the figure. 1 via connections 32 to 36.
La figure 2 est un schéma électrique interne d'une des sondes 18 ou 20 de la figure 1 et de sa connexion avec I1U. C. E. Chaque sonde 18, 20 comporte un circuit de chauffage Cc comportant une résistance de chauffage Rc et un circuit de signal de sonde Cs comportant une résistance interne Rs de l'élément sensible de l'élément de la sonde 1 ou 20. Le circuit de chauffage Cc de la sonde est relié à l'UCE par les connexions a et b et le circuit délivrant le signal de la sonde est relié au moteur par les connexions c et d. L1U. C. E calcule l'intensité du courant traversant le circuit de chauffage Cc à partir de la tension qu'elle mesure aux bornes de ce circuit Cc et d'une résistance interne (non représentée sur la figure) implantée dans un montage dit à miroir de courant.
L'invention propose un procédé et un dispositif de diagnostic du circuit de chauffage de la sonde à oxygène.FIG. 2 is an internal circuit diagram of one of the probes 18 or 20 of FIG. 1 and of its connection with I 1 ECU. Each probe 18, 20 comprises a heating circuit Cc comprising a heating resistor Rc and a signal circuit. sensor Cs having an internal resistance Rs of the sensing element of the element of the probe 1 or 20. The heating circuit Cc of the probe is connected to the ECU by the connections a and b and the circuit delivering the signal of the probe is connected to the motor by the connections c and d. L 1 UC E calculates the intensity of the current flowing through the heating circuit Cc from the voltage it measures at the terminals of this circuit Cc and from an internal resistor (not shown in the figure) implanted in an assembly said to current mirror. The invention proposes a method and a device for diagnosing the heating circuit of the oxygen sensor.
On reporte à présent à la figure 3 qui est un ordinogramme des différentes étapes du procédé de diagnostic selon l'invention. A l'étape 50 I1U. C. E initialise toutes les variables utilisées pour réaliser le diagnostic du circuit de chauffage Cc. Puis, à l'étape 52 I1U. C. E vérifie que les conditions de réalisation du test sont réunies:Referring now to Figure 3 which is a flow chart of the various steps of the diagnostic method according to the invention. In step 50 I 1 UC E initializes all the variables used to perform the diagnosis of the heating circuit Cc. Then, in step 52 I 1 UC E verifies that the conditions for carrying out the test are met:
- le moteur a au moins atteint une plage de régime prédéterminé, par exemple comprise entre 750 -800 tours par minute,the engine has at least reached a predetermined speed range, for example between 750 and 800 revolutions per minute,
- la température du liquide de refroidissement est supérieure à une valeur prédéterminée, par exemple supérieure -7°,the temperature of the coolant is greater than a predetermined value, for example greater than -7 °,
- les diagnostics électriques de la sonde 18 ou 20 n'ont détecté de défauts ni sur le circuit de chauffage Cc ni sur le circuit de signal Cs, - les autres capteurs, par exemple le capteur de température du liquide de refroidissement, permettant de réaliser le diagnostic ne sont pas déclarés défaillants.the electrical diagnoses of the probe 18 or 20 have detected no defects on the heating circuit Cc or on the signal circuit Cs; the other sensors, for example the temperature sensor of the coolant, making it possible to carry out the diagnosis are not declared defective.
Lorsque ces conditions sont réunies, toujours à l'étape 52, une temporisation Tempo est lancée par I1U. C. E avant la réalisation du diagnostic proprement dit. Cette temporisation permet d'attendre la stabilisation de la température de la résistance de chauffage Rc. En effet, la valeur de la résistance de chauffage Rc varie en fonction de la température ce qui provoque des variations importantes de la valeur du courant de chauffage traversant le circuit de chauffage Cc et qui peut par conséquent influer sur le résultat du diagnostic.When these conditions are met, still at step 52, a delay timer is started by I 1 UC E before the actual diagnosis is made. This delay makes it possible to wait for the stabilization of the temperature of the heating resistor Rc. Indeed, the value of the heating resistor Rc varies depending on the temperature which causes significant variations in the value of the heating current passing through the heating circuit Cc and which can therefore affect the result of the diagnosis.
Le diagnostic de la sonde pouvant être inhibé par d'autres stratégies de contrôle moteur prioritaires, à l'étape 54 I1U. C. E vérifie que le diagnostic du
circuit de chauffage peut être effectué. Cette étape peut être effectuée en vérifiant l'état logique d'un booléen d'autorisation booM . Si le diagnostic n'est pas autorisé, l'étape 52 est de nouveau effectuée. Dans le cas contraire, à l'étape 56 I1U. C. E vérifie que la commande de chauffage a bien été activée en vérifiant l'état logique d'un booléen d'activation de chauffage bool2. Si la commande de chauffage n'a pas été activée l'étape 54 est nouveau réalisée. Dans le cas contraire à l'étape 58, I1U. C. E calcule une valeur moyenne Imoy du courant traversant le circuit de chauffage Cc durant une fenêtre élémentaire d'acquisition. On entend ici par fenêtre élémentaire d'acquisition, ou fenêtre élémentaire, une durée prédéterminée durant laquelle la valeur moyenne du courant Imoy est calculée en continue par I1U. C. E. Tant que la durée de la fenêtre élémentaire n'est pas écoulée, les étapes 56 et 58 sont réalisée. L1U. C. E vérifie que la durée de la fenêtre élémentaire d'acquisition est écoulée à l'étape 60. A l'étape 62, lorsqu'une fenêtre élémentaire d'acquisition est écoulée, I1U. C. E compare la valeur moyenne du courant de chauffage Imoy ayant traversé le circuit de chauffage Cc durant une fenêtre élémentaire à une valeur de seuil S1 et déclare cette fenêtre défaillante si la valeur moyenne Imoy du courant est inférieure au seuil S1. A l'étape 64 I1U. C. E compte le nombre de fenêtres élémentaire Nf écoulées et le compare à une valeur de seuil Nmax. Si le nombre de fenêtre d'acquisition écoulée est inférieur à Nmax l'étape 54 est de nouveau effectuée. Si tel n'est pas le cas, à l'étapes 66 I1U. C. E déclare le circuit de chauffage défaillant si toutes les fenêtres d'acquisition élémentaires ont été déclarées comme étant défaillantes. Selon une autre variante de réalisation L1U. C. E peut déclarer le circuit comme étant défaillant si certaines fenêtres élémentaires seulement ont été déclarées défaillantes.
Lorsqu'une défaillance a été détectée par le diagnostic selon l'invention, elle peut être signalée au conducteur du véhicule, par exemple grâce à l'allumage d'un voyant lumineux au tableau de bord.The diagnosis of the probe that can be inhibited by other priority motor control strategies, at step 54 I 1 UC E, verifies that the diagnosis of the heating circuit can be performed. This step can be performed by checking the logical state of a booM authorization boolean. If the diagnosis is not allowed, step 52 is performed again. Otherwise, in step 56 I 1 UC E verifies that the heating command has been activated by checking the logic state of a heating activation boolean bool2. If the heating control has not been activated, step 54 is performed again. In the opposite case to step 58, I 1 UC E calculates an average value Imoy of the current flowing through the heating circuit Cc during a basic acquisition window. An elementary acquisition window, or elementary window, is here understood to mean a predetermined duration during which the average value of the current Imoy is calculated continuously by I 1 ECU. As long as the duration of the elementary window has not elapsed, the steps 56 and 58 are realized. L 1 UC E verifies that the duration of the basic acquisition window has elapsed in step 60. In step 62, when a basic acquisition window has elapsed, I 1 UC E compares the average value of the current heating Imoy having passed through the heating circuit Cc during a basic window to a threshold value S1 and declares this window fault if the average value Imoy of the current is below the threshold S1. In step 64 I 1 UC E counts the number of elementary windows Nf elapsed and compares it with a threshold value Nmax. If the number of acquisition window elapsed is less than Nmax, step 54 is performed again. If this is not the case, at step 66 I 1 UC E declares the heating circuit faulty if all the basic acquisition windows have been declared as faulty. According to another alternative embodiment L 1 UC E can declare the circuit to be faulty if only certain elementary windows have been declared faulty. When a fault has been detected by the diagnosis according to the invention, it can be signaled to the driver of the vehicle, for example by lighting a warning light on the dashboard.
Grâce au procédé selon l'invention, il est possible de faire la différence entre une défaillance ponctuelle qui ne sera détectée que sur une fenêtre élémentaire d'acquisition et une défaillance permanente qui sera détectée sur un grand nombre ou sur l'ensemble des fenêtres élémentaires d'acquisition. Grâce à cette caractéristique on évite les fausses détections et le diagnostic est plus robuste.With the method according to the invention, it is possible to differentiate between a point failure which will be detected only on a basic acquisition window and a permanent failure which will be detected on a large number or on all the elementary windows. acquisition. This feature avoids false detection and the diagnosis is more robust.
En outre, le nombre de fenêtres élémentaires de détection est paramétrable. Il est ainsi possible d'adapter le procédé de diagnostic à différents types de sondes à oxygène.
In addition, the number of elementary detection windows is configurable. It is thus possible to adapt the diagnostic process to different types of oxygen sensors.
Claims
1. Procédé de diagnostic de l'état de fonctionnement du circuit de chauffage d'une sonde à oxygène caractérisé en ce qu'il comporte :1. A method for diagnosing the operating state of the heating circuit of an oxygen sensor, characterized in that it comprises:
- a) une étape (58) de calcul de la valeur moyenne (Imoy) du courant de chauffage de la sonde durant une durée prédéterminée appelée fenêtre élémentaire,a) a step (58) for calculating the average value (Imoy) of the heating current of the probe during a predetermined duration called elementary window,
- b) une étape (62) de comparaison de cette valeur moyenne (Imoy) à une valeur de seuil (S1) pour effectuer un diagnostic préliminaire du fonctionnement du circuit de chauffage (Cc) de la sonde durant cette fenêtre élémentaire, c) une étape (56,58,60) au cours de laquelle les étapes a et b sont répétées un nombre (Nmax) prédéterminé de fois, d) une étape (66) de diagnostic définitif du circuit de chauffage de la sonde en fonction du résultat des diagnostics préliminaires.b) a step (62) of comparing this average value (Imoy) with a threshold value (S1) to perform a preliminary diagnosis of the operation of the heating circuit (Cc) of the probe during this elementary window, c) a step (56, 58, 60) in which steps a and b are repeated a predetermined number (Nmax), d) a definitive diagnostic step (66) of the probe heating circuit according to the result of the preliminary diagnoses.
2. Procédé selon la revendication précédente caractérisé en ce que durant l'étape d) on déclare le circuit de chauffage (Cc) de la sonde défaillant si le nombre de fenêtres élémentaires pour lesquels le fonctionnement du circuit de chauffage de la sonde a été déclaré défaillant est supérieur à un seuil.2. Method according to the preceding claim characterized in that during step d) declares the heating circuit (Cc) of the faulty probe if the number of elementary windows for which the operation of the heating circuit of the probe has been declared. failing is greater than a threshold.
3. Procédé selon la revendication 1 caractérisé en ce que durant l'étape d) on déclare le circuit de chauffage (Cc) de la sonde défaillant si pour toutes les fenêtres élémentaires le fonctionnement du circuit de chauffage a été déclaré défaillant.3. Method according to claim 1 characterized in that during step d) declares the heating circuit (Cc) of the faulty probe if for all the elementary windows the operation of the heating circuit has been declared defective.
4. Procédé de diagnostic selon l'une quelconque des revendications précédentes caractérisé en ce que lors de l'étape (62) de diagnostic préliminaire le fonctionnement du circuit de chauffage de la sonde est déclaré défaillant si la valeur moyenne du courant est inférieure au seuil (S1 ).4. Diagnostic method according to any one of the preceding claims, characterized in that during the step (62) of diagnosis preliminary operation of the heating circuit of the probe is declared faulty if the average value of the current is below the threshold (S1).
5. Procédé selon l'une quelconque des revendications précédentes caractérisé en ce qu'il comporte une étape (52) de temporisation et de stabilisation de la température de la résistance de chauffage (Rc) du circuit de chauffage (Cc) de la sonde (18,20), cette étape étant préalable à l'étape a).5. Method according to any one of the preceding claims, characterized in that it comprises a step (52) for delaying and stabilizing the temperature of the heating resistor (Rc) of the heating circuit (Cc) of the probe ( 18,20), this step being prior to step a).
6. Procédé de diagnostic selon l'une des revendications 2 à 5 caractérisé en ce que la défaillance du circuit de chauffage de la sonde est signalée au conducteur.6. Diagnostic method according to one of claims 2 to 5 characterized in that the failure of the heating circuit of the probe is signaled to the driver.
7. Dispositif de diagnostic de l'état de fonctionnement du circuit de chauffage d'une sonde à oxygène, le dispositif comportant une unité électronique de commande (16) apte à être reliée au circuit de chauffage (Cc) de la sonde (18,20) caractérise en ce que le dispositif comporte en outre des moyens pour: - calculer de la valeur moyenne (Imoy) du courant de chauffage de la sonde durant une durée prédéterminée, appelée fenêtre élémentaire,7. Device for diagnosing the operating state of the heating circuit of an oxygen sensor, the device comprising an electronic control unit (16) adapted to be connected to the heating circuit (Cc) of the probe (18, 20) characterized in that the device further comprises means for: calculating the average value (Imoy) of the heating current of the probe during a predetermined duration, called the elementary window,
- comparer cette valeur moyenne (Imoy) à une valeur de seuil (S1) pour effectuer un diagnostic préliminaire du fonctionnement du circuit de chauffage de la sonde durant cette fenêtre élémentaire,comparing this average value (Imoy) with a threshold value (S1) to perform a preliminary diagnosis of the operation of the heating circuit of the probe during this elementary window,
- diagnostiquer le fonctionnement du circuit de chauffage de la sonde en fonction du résultat des diagnostics préliminaires. - diagnose the operation of the heating circuit of the probe according to the result of the preliminary diagnoses.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/FR2008/052250 WO2010066954A1 (en) | 2008-12-09 | 2008-12-09 | Method and device for diagnosing the operation of an oxygen probe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/FR2008/052250 WO2010066954A1 (en) | 2008-12-09 | 2008-12-09 | Method and device for diagnosing the operation of an oxygen probe |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2010066954A1 true WO2010066954A1 (en) | 2010-06-17 |
Family
ID=40791317
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/FR2008/052250 WO2010066954A1 (en) | 2008-12-09 | 2008-12-09 | Method and device for diagnosing the operation of an oxygen probe |
Country Status (1)
| Country | Link |
|---|---|
| WO (1) | WO2010066954A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR3111951A1 (en) * | 2020-06-29 | 2021-12-31 | Vitesco Technologies | Motor controller adapted to identify an unsuitable richness sensor and associated process |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5218946A (en) * | 1991-09-26 | 1993-06-15 | Robert Bosch Gmbh | Method and arrangement for checking the operability of an electric heater in a motor vehicle |
| US5228426A (en) * | 1992-10-28 | 1993-07-20 | Ford Motor Company | Oxygen sensor system with an automatic heater malfunction detector |
| US5505183A (en) * | 1995-03-10 | 1996-04-09 | Ford Motor Company | Method and system for controlling emissions from an internal combustion engine |
| EP1734241A1 (en) * | 2005-06-17 | 2006-12-20 | Ford Global Technologies, LLC | Method for diagnosing a secondary lambda probe in a catalytic converter |
| FR2924167A1 (en) * | 2007-11-27 | 2009-05-29 | Renault Sas | Heating circuit operating state diagnosing method for lambda sensor in motor vehicle, involves carrying out final diagnosis of heating circuit of oxygen sensor relative to result of preliminary diagnoses of operation of heating circuit |
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2008
- 2008-12-09 WO PCT/FR2008/052250 patent/WO2010066954A1/en active Application Filing
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5218946A (en) * | 1991-09-26 | 1993-06-15 | Robert Bosch Gmbh | Method and arrangement for checking the operability of an electric heater in a motor vehicle |
| US5228426A (en) * | 1992-10-28 | 1993-07-20 | Ford Motor Company | Oxygen sensor system with an automatic heater malfunction detector |
| US5505183A (en) * | 1995-03-10 | 1996-04-09 | Ford Motor Company | Method and system for controlling emissions from an internal combustion engine |
| EP1734241A1 (en) * | 2005-06-17 | 2006-12-20 | Ford Global Technologies, LLC | Method for diagnosing a secondary lambda probe in a catalytic converter |
| FR2924167A1 (en) * | 2007-11-27 | 2009-05-29 | Renault Sas | Heating circuit operating state diagnosing method for lambda sensor in motor vehicle, involves carrying out final diagnosis of heating circuit of oxygen sensor relative to result of preliminary diagnoses of operation of heating circuit |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR3111951A1 (en) * | 2020-06-29 | 2021-12-31 | Vitesco Technologies | Motor controller adapted to identify an unsuitable richness sensor and associated process |
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