EP0856098A1 - Device and method for diagnosing the condition of a probe upstream from a catalytic converter - Google Patents
Device and method for diagnosing the condition of a probe upstream from a catalytic converterInfo
- Publication number
- EP0856098A1 EP0856098A1 EP96934934A EP96934934A EP0856098A1 EP 0856098 A1 EP0856098 A1 EP 0856098A1 EP 96934934 A EP96934934 A EP 96934934A EP 96934934 A EP96934934 A EP 96934934A EP 0856098 A1 EP0856098 A1 EP 0856098A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- krich
- value
- probe
- signal
- krichp
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000000523 sample Substances 0.000 title claims abstract description 86
- 238000011144 upstream manufacturing Methods 0.000 title claims abstract description 42
- 230000003197 catalytic effect Effects 0.000 title claims abstract description 23
- 238000000034 method Methods 0.000 title claims abstract description 14
- 238000002485 combustion reaction Methods 0.000 claims abstract description 8
- 238000002347 injection Methods 0.000 claims abstract description 7
- 239000007924 injection Substances 0.000 claims abstract description 7
- 238000012937 correction Methods 0.000 claims description 19
- 238000004364 calculation method Methods 0.000 claims description 18
- 230000002950 deficient Effects 0.000 claims description 12
- 239000000446 fuel Substances 0.000 claims description 12
- 238000001914 filtration Methods 0.000 claims description 9
- 230000006870 function Effects 0.000 claims description 6
- 230000015654 memory Effects 0.000 claims description 6
- 238000005259 measurement Methods 0.000 claims description 5
- 238000002405 diagnostic procedure Methods 0.000 claims description 4
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims 2
- 238000010586 diagram Methods 0.000 description 13
- 238000003745 diagnosis Methods 0.000 description 8
- 239000003344 environmental pollutant Substances 0.000 description 7
- 231100000719 pollutant Toxicity 0.000 description 7
- 239000007789 gas Substances 0.000 description 5
- 230000007704 transition Effects 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000032683 aging Effects 0.000 description 2
- 230000006399 behavior Effects 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 230000007257 malfunction Effects 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 238000012774 diagnostic algorithm Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
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
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
-
- 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
- F02D41/1439—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the position of the sensor
- F02D41/1441—Plural 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
- F02D41/1493—Details
- F02D41/1495—Detection of abnormalities in the air/fuel ratio feedback system
-
- 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
- F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
- F02D2041/1413—Controller structures or design
- F02D2041/1432—Controller structures or design the system including a filter, e.g. a low pass or high pass filter
Definitions
- the invention relates to internal combustion engines of the injection type and comprising a catalytic exhaust system preceded by a probe and, more particularly in such engines, a device and a method for diagnosing the state of the probe arranged in upstream of the catalytic converter.
- the diagnosis then consists in declaring the probe failure if one or more faults are detected.
- Such a diagnostic method is based on the analysis of the behavior of the probe in order to deduce therefrom a state of the probe by presuming degradation modes. For example, an aged probe has reduced voltage dynamics and / or extended tilt times.
- a dynamic reduced voltage probe may be good vis-à-vis the emission of pollutants if only this characteristic is affected.
- An object of the present invention is therefore to implement a device and a method for diagnosing the state of a probe disposed upstream of a catalytic converter associated with an internal combustion engine of the injection type which does not have the above-listed drawbacks of prior art devices and methods.
- Another object of the present invention is also to implement a device and a method for diagnosing the state of an upstream probe which does not call for measurements of the intrinsic characteristics of the probe.
- the method of the invention is based on monitoring the characteristics of the wealth loop which have an influence on the pollutant emissions, namely, the average period and the average wealth of the loop.
- the state of the upstream probe is evaluated on the basis of the effects it produces on the wealth loop, that is to say on pollutant emissions, and not on the basis of its own characteristics.
- the effects of the state of the upstream probe are likely to generate pollutant emissions by exceeding the limits of the "window" for proper operation of the catalytic converter, this excess being due to the drift in the average operating richness and / or the average period of the wealth loop which becomes too long.
- the invention proposes to implement a second non-linear probe which is arranged downstream of the catalytic converter and which is an integral part of a second feedback loop thanks to which the output voltage v ava ⁇ of the second probe, called the downstream probe, is controlled by a reference voltage VC ava ⁇ corresponding to the center of the window for the correct operation of the catalytic converter.
- the signal which is provided by this loop is used to modify the signal of the first feedback loop comprising the upstream probe.
- the invention relates to a device for diagnosing the state of a nonlinear probe disposed upstream of a catalytic converter associated with an internal combustion engine of the injection type controlled by an electronic computer, said engine comprising a first loop of control, including said non-linear probe, to supply the computer with a first KCL correction signal of the quantity of fuel injected and a second control loop, including a second non-linear probe arranged downstream of said catalytic converter to provide a second signal for correcting KRICH of the quantity of fuel injected, said diagnostic device being characterized in that it comprises: - a filtering circuit to which the second KRICH correction signal is applied to supply a filtered signal KRICHp, - a measuring circuit to which the output signal V t from the upstream probe is applied to determine the average value T of the correction period d e the first control loop, and - a logic circuit to determine the good or defective DIAG state of the upstream probe as a function of the values of the filtered signal KRICHp and of the average period T
- the logic circuit determines that the upstream probe is defective if the filtered signal is greater than a maximum value or less than a minimum value or even if the average period is greater than a maximum value.
- the maximum and minimum values of the filtered signal KRICHp are determined by calibration as a function of the value of the average period and are recorded in a memory. This memory is addressed by the value of the average period to provide the maximum and minimum values to which the value of the filtered signal is compared.
- the invention also relates to a method which comprises the following steps: filtering the second correction signal KRICH to obtain a filtered signal KRICHp,
- FIG. 1 is a block diagram of a double wealth control loop system to which the invention applies;
- FIG. 2-A and 2-B are diagrams showing how the richness correction is carried out with a single feedback loop comprising a probe upstream of the catalytic converter;
- FIGS 3-A and 3-B are diagrams showing a way of correcting the richness using a second feedback loop comprising a probe downstream of the catalytic converter;
- FIG. 4 is a diagram showing how to filter the correction signal KRICH to obtain a filtered signal KRICHp;
- FIG. 5 is a diagram showing an algorithm for calculating the average period of the signal from the upstream probe
- FIG. 6 is a diagram showing the curves which determine the zones of correct or defective operation of the upstream probe
- FIG. 7 is a diagram showing a decision algorithm for determining the state of the upstream probe.
- an internal combustion engine 10 is controlled, in a known manner, by an electronic computer 12.
- the exhaust gases from this engine are filtered by an exhaust pipe 14 of catalytic type, from which they escape towards the open air.
- a first probe 16 is disposed at the inlet of the exhaust pipe and measures the content of one of the main components of the exhaust gases, this component usually being oxygen.
- This probe is of the non-linear type and is often called, as indicated above, "lambda" probe or EGO probe.
- This probe provides on its output terminal an upstream electrical signal V ( Figure 2-A) which is applied to a comparator circuit 18 in which V a ⁇ non ⁇ . is compared with a threshold voltage v S a ⁇ rt ⁇ n -t- to determine the sign of V a ⁇ nont with respect to this threshold.
- the value of the threshold v S a ⁇ non t depends on the characteristics of the probe and corresponds to the tilting voltage of the probe when the stoichiometric conditions are met.
- the output terminal of the comparator circuit 18, which provides a binary signal 1 or 0, is connected to the input terminal of a first correction regulator 20 for richness regulation which is of the proportional type of gain P and integral of gain I
- the corrector circuit 20 supplies a signal KCL which has the form represented by the diagram of FIG. 2-B. It is this signal KCL which is supplied to the computer 12 to control the quantity of fuel to be injected.
- KCL which has the form represented by the diagram of FIG. 2-B. It is this signal KCL which is supplied to the computer 12 to control the quantity of fuel to be injected.
- This circuit 24 essentially consists of a comparator 28 to which the signal v ava ⁇ and a so-called reference signal VCa., v ,, al ! and a third corrector circuit 30 to which the signal (V downstream - VC downstream ) supplied by the comparator circuit 28 is applied.
- the third corrector circuit 30 is for example of the proportional and integral type and supplies the signal KRICH which is applied to the second correction circuit 22.
- the second corrector circuit 22 can introduce the KRICH correction in different ways, one of which will be explained in relation to the time diagrams of FIGS. 3-A and 3-B. These diagrams are plots of the KCL signal as modified by the second corrector circuit 22, the modified KCL signal being called KCL. ,,.
- the signal KRICH is applied during the lean-to-rich transitions which are detected by the first probe, which corresponds to the falling edge of the signal KCL.
- KRICH> 0 enrichment
- the plot of KCL ⁇ is that of figure 3-A while in the case where KRICH ⁇ 0 (depletion), the plot of KCL ⁇ is that of figure 3-B .
- the device for diagnosing the state of the probe 16 comprises the elements represented inside the rectangle 40 of the diagram in FIG. 1. It is a filter 32 to which the output signal KRICH of the correcting circuit is applied. 24 of the second loop as well as a calculation circuit 34 of the average period T m of the signal v amcm t of - The upstream probe 16.
- the output terminals of the filter 32 and of the calculation circuit 34 are connected to a logic circuit 36 which determine the good or bad state of the probe 16 as a function of the output signal KRICHp of the filter 32 and of the value T m of the mean period of the signal v am ⁇ nf
- the binary sig nal 1 or O of the good or bad state of probe 16 appears on the DIAG output terminal of logic circuit 36.
- the information which is provided by the computer 12 is as follows:
- Circuits 32 and 34 process the information listed above and only allow filtering and calculation of T m if the following conditions are met simultaneously:
- REG min and REG ma ⁇ being respectively the minimum and maximum values of the engine speed REG between which the diagnosis can be carried out;
- P m i n and p max being respectively the minimum and maximum values of the pressure P of the inlet manifold between which the diagnosis can be carried out.
- the filtering 32 performs the calculation of the filtered richness correction KRICHp according to the algorithm of FIG. 4. This calculation (step 42) is only carried out if the conditions listed above are fulfilled (step 44) and, in this case, the average wealth KRICHp is given by:
- KRICHp KRICHp + K (KRICH - KRICHp) with K a filtering factor between 0 and 1.
- the calculation circuit 34 performs the calculation of the average period T m according to the algorithm of FIG. 5. This calculation is only carried out if the conditions listed above are met (step 50). This calculation of the mean period T ⁇ is to count the transitions of the voltage V upstream of a value below the threshold vs. upstream ⁇ a vaj - eur upper threshold for a certain time interval T D and dividing the interval T D by the number N of transitions that have been detected.
- the algorithm for calculating the average period T of the first loop is represented by the diagram in FIG. 5.
- the first step (50) consists in checking whether the diagnostic conditions listed above are fulfilled. If the answer is "YES”, the step of counting 52 of the time T is started, that is to say that the calculation of the average period T_ begins.
- step 54 the old state STATE A of the probe corresponding to v upstream ⁇ vs upstream
- the counter for the duration T D of the diagnosis is increased by the value T of the counter 52.
- the next step 68 resets the counter 52 to zero for a new measurement T of the current period.
- STATE A 1 so that the condition of step 56 is not fulfilled, in which case the steps of the algorithm are repeated.
- the logic circuit 36 performs the steps of the algorithm of FIG. 7 so as to compare the value of KRICHp with values which have been determined to be limit values beyond which the probe is considered to be defective and this for a value determined T m of the mean period.
- These limit values called KRICH ma ⁇ for an excessively high richness and KRICH- j ⁇ for an excessive impoverishment, are determined by a calibration using a series of probes whose aging characteristics are known. This calibration makes it possible to plot the KRICH ⁇ na ⁇ and KRICH m ⁇ n curves as a function of the period T m (FIG. 6), curves which can be stored in the form of two cartographic tables or a single table combining the two.
- the cartographic tables can be produced by memories which are addressed by the value of T m , and the values read are KRICrL and KRI ⁇ L j . ⁇ For the value of T m (FIG. 6).
- the diagnosis is complete (step 94) and a new diagnosis can be launched to obtain a new value of KRICHp and of T m .
- KRICH ' max , KRICH' min and T ' ma ⁇ it is possible to limit oneself to choosing fixed thresholds for KRICH ' max , KRICH' min and T ' ma ⁇ and it is therefore no longer necessary to have two cartographic tables.
- the value of KRICHp is compared with the two selected thresholds while the value T m of the average value is compared with the threshold T ' a ⁇ . If KRICHp is greater than KRICH ' ma ⁇ , or less than KRICH' m ⁇ n or greater than T'_ a ⁇ , the probe is considered to be defective. Otherwise, the probe is considered good.
- the algorithm of FIG. 7 can be implemented in the form of software or in that of electronic circuits in which the comparison steps 80, 82 and 84 would be performed by number comparators.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
Abstract
Description
DISPOSITIF ET PROCEDE DE DIAGNOSTIC DE L'ETAT D'UNE SONDE DISPOSEE EN AMONT DU POT CATALYTIQUE. DEVICE AND METHOD FOR DIAGNOSING THE CONDITION OF A PROBE PROVIDED UPSTREAM OF THE CATALYTIC POT.
L'invention concerne les moteurs à combustion interne du type à injection et comportant un pot d'échappement catalytique précédé d'une sonde et, plus particulièrement dans de tels moteurs, un dispositif et un procédé pour diagnostiquer l'état de la sonde disposée en amont du pot catalytique.The invention relates to internal combustion engines of the injection type and comprising a catalytic exhaust system preceded by a probe and, more particularly in such engines, a device and a method for diagnosing the state of the probe arranged in upstream of the catalytic converter.
Il est connu d'utiliser des systèmes pour modifier la quantité du carburant qui est injectée dans un moteur en fonction de la composition des gaz d'échappement et, plus particulièrement, de la teneur en oxygène de ces gaz. A cet effet, la teneur en oxygène est mesurée à l'aide d'une sonde non linéaire dite sonde "lambda" ou sonde EGO, EGO étant l'acronyme anglo-saxon pour "Exhaust Gas Oxygen". Une telle sonde est disposée en amont du pot d'échappement catalytique et le signal fourni par cette sonde sert à modifier la quantité de carburant qui est injectée dans les cylindres du moteur par l'intermédiaire d'une première boucle de contre- réaction. Pour cette raison, cette sonde est aussi appelée sonde de régulation de richesse.It is known to use systems to modify the quantity of fuel which is injected into an engine as a function of the composition of the exhaust gases and, more particularly, of the oxygen content of these gases. To this end, the oxygen content is measured using a non-linear probe called the "lambda" probe or EGO probe, EGO being the acronym for "Exhaust Gas Oxygen". Such a probe is arranged upstream of the catalytic converter and the signal supplied by this probe is used to modify the quantity of fuel which is injected into the engine cylinders via a first feedback loop. For this reason, this probe is also called a richness regulation probe.
Il est clair que le mauvais état de cette sonde conduit à un mauvais fonctionnement du moteur et du pot catalytique, ce qui induit des émissions de polluants à des valeurs anormalement élevées. Il est donc important de déterminer l'état de cette sonde à tout moment de manière à diagnostiquer son mauvais fonctionnement lorsque son état s'est détérioré au-delà de certaines limites. Les solutions actuelles de diagnostic de l'état de la sonde amont consistent à analyser le comportement de la sonde en réponse à des excitations de richesse en boucle ouverte ou en boucle fermée et à surveiller les paramètres suivants :It is clear that the poor condition of this probe leads to a malfunction of the engine and the catalytic converter, which induces emissions of pollutants at abnormally high values. It is therefore important to determine the state of this probe at all times so as to diagnose its malfunction when its state has deteriorated beyond certain limits. Current solutions for diagnosing the state of the upstream probe consist in analyzing the behavior of the probe in response to rich loop excitations or closed loop and to monitor the following parameters:
- la tension minimale fournie par la sonde : si elle est trop élevée, il y a défaut ;- the minimum voltage supplied by the probe: if it is too high, there is a fault;
- la tension maximale fournie par la sonde : si elle est trop faible, il y a défaut ;- the maximum voltage supplied by the probe: if it is too low, there is a fault;
- le temps de basculement pauvre-riche : s'il est trop long, il y a défaut ; - le temps de basculement riche-pauvre : s'il est trop long, il y a défaut ;- the poor-rich changeover time: if it is too long, there is a fault; - the rich-poor changeover time: if it is too long, there is a fault;
- la période du signal fourni par la sonde en boucle fermée : si elle est trop longue, il y a défaut.- the period of the signal supplied by the closed loop probe: if it is too long, there is a fault.
Le diagnostic consiste alors à déclarer la panne de la sonde si un ou plusieurs défauts sont détectés.The diagnosis then consists in declaring the probe failure if one or more faults are detected.
Un tel procédé de diagnostic est basé sur l'analyse du comportement de la sonde pour en déduire un état de la sonde en présumant des modes de dégradation. Par exemple, une sonde âgée a une dynamique de tension réduite et/ou des temps de basculement allongés.Such a diagnostic method is based on the analysis of the behavior of the probe in order to deduce therefrom a state of the probe by presuming degradation modes. For example, an aged probe has reduced voltage dynamics and / or extended tilt times.
L'inconvénient d'un tel procédé de diagnostic est qu'il n'existe pas de bijection parfaite entre ces mesures et les émissions de polluants.The disadvantage of such a diagnostic method is that there is no perfect bijection between these measurements and the pollutant emissions.
En outre, la calibration des seuils de détection des défauts s'avère très délicate et nécessite :In addition, the calibration of fault detection thresholds is very delicate and requires:
- une connaissance parfaite des modes de vieillissement des sondes,- a perfect knowledge of the aging modes of the probes,
- de nombreux essais pour établir un lien entre les dégradations mesurées des paramètres et leurs effets sur les émissions de polluants.- numerous attempts to establish a link between the measured degradations of the parameters and their effects on pollutant emissions.
Par ailleurs, il n'est pas possible de garantir dans tous les cas la fiabilité du diagnostic. Par exemple, une sonde à dynamique en tension réduite peut s'avérer bonne vis-à-vis de l'émission de polluants si seule cette caractéristique est affectée.In addition, it is not possible to guarantee in all cases the reliability of the diagnosis. For example, a dynamic reduced voltage probe may be good vis-à-vis the emission of pollutants if only this characteristic is affected.
Un but de la présente invention est donc de mettre en oeuvre un dispositif et un procédé de diagnostic de l'état d'une sonde disposée en amont d'un pot catalytique associé à un moteur à combustion interne du type à injection qui ne présente pas les inconvénients ci-dessus énumérés des dispositifs et procédés de l'art antérieur. Un autre but de la présente invention est aussi de mettre en oeuvre un dispositif et un procédé de diagnostic de l'état d'une sonde amont qui ne fait pas appel à des mesures des caractéristiques intrinsèques de la sonde. Le procédé de l'invention est basé sur la surveillance des caractéristiques du bouclage de richesse qui ont une influence sur les émissions de polluants, à savoir, la période moyenne et la richesse moyenne du bouclage. De cette manière, l'état de la sonde amont est évalué à partir des effets qu'elle produit sur le bouclage de richesse, c'est-à-dire sur les émissions de polluants, et non pas à partir de ses caractéristiques propres. Les effets de l'état de la sonde amont sont susceptibles d'engendrer des émissions de polluants par dépassement des limites de la "fenêtre" de bon fonctionnement du pot catalytique, ce dépassement étant dû à la dérive de la richesse moyenne de fonctionnement et/ou à la période moyenne de la boucle de richesse qui devient trop longue. Pour détecter la dérive de la richesse moyenne de fonctionnement, l'invention propose de mettre en oeuvre une deuxième sonde non-linéaire qui est disposée en aval du pot catalytique et qui fait partie intégrante d'une deuxième boucle de contre-réaction grâce à laquelle la tension de sortie v avaι de la deuxième sonde, dite sonde aval, est asservie à une tension de consigne VCava^ correspondant au centre de la fenêtre de bon fonctionnement du pot catalytique. Le signal qui est fourni par cette boucle est utilisé pour modifier le signal de la première boucle de contre-réaction comprenant la sonde amont.An object of the present invention is therefore to implement a device and a method for diagnosing the state of a probe disposed upstream of a catalytic converter associated with an internal combustion engine of the injection type which does not have the above-listed drawbacks of prior art devices and methods. Another object of the present invention is also to implement a device and a method for diagnosing the state of an upstream probe which does not call for measurements of the intrinsic characteristics of the probe. The method of the invention is based on monitoring the characteristics of the wealth loop which have an influence on the pollutant emissions, namely, the average period and the average wealth of the loop. In this way, the state of the upstream probe is evaluated on the basis of the effects it produces on the wealth loop, that is to say on pollutant emissions, and not on the basis of its own characteristics. The effects of the state of the upstream probe are likely to generate pollutant emissions by exceeding the limits of the "window" for proper operation of the catalytic converter, this excess being due to the drift in the average operating richness and / or the average period of the wealth loop which becomes too long. To detect the drift in the average operating richness, the invention proposes to implement a second non-linear probe which is arranged downstream of the catalytic converter and which is an integral part of a second feedback loop thanks to which the output voltage v ava ι of the second probe, called the downstream probe, is controlled by a reference voltage VC ava ^ corresponding to the center of the window for the correct operation of the catalytic converter. The signal which is provided by this loop is used to modify the signal of the first feedback loop comprising the upstream probe.
Un tel système d'asservissement de la richesse à double boucle de commande est décrit dans la demande de brevet déposée ce jour par la demanderesse et intitulée : "SYSTEME ET PROCEDE DE DOUBLE BOUCLE DE COMMANDE POUR MOTEUR A COMBUSTION INTERNE" .Such a richness control system with double control loop is described in the patent application filed today by the applicant and entitled: "SYSTEM AND METHOD OF DOUBLE CONTROL LOOP FOR INTERNAL COMBUSTION ENGINE".
L'invention concerne un dispositif de diagnostic de l'état d'une sonde non linéaire disposée en amont d'un pot catalytique associé à un moteur à combustion interne du type à injection commandée par un ordinateur électronique, ledit moteur comprenant une première boucle de commande, incluant ladite sonde non linéaire, pour fournir à l'ordinateur un premier signal de correction KCL de la quantité de carburant injectée et une deuxième boucle de commande, incluant une deuxième sonde non linéaire disposée en aval dudit pot catalytique pour fournir un deuxième signal de correction KRICH de la quantité de carburant injectée, ledit dispositif de diagnostic étant caractérisé en ce qu'il comprend : - un circuit de filtrage auquel est appliqué le deuxième signal de correction KRICH pour fournir un signal filtré KRICHp, - un circuit de mesure auquel est appliqué le signal de sortie V t de la sonde amont pour déterminer la valeur moyenne T de la période de correction de la première boucle de commande, et - un circuit logique pour déterminer l'état DIAG bon ou défectueux de la sonde amont en fonction des valeurs du signal filtré KRICHp et de la période moyenne Tm.The invention relates to a device for diagnosing the state of a nonlinear probe disposed upstream of a catalytic converter associated with an internal combustion engine of the injection type controlled by an electronic computer, said engine comprising a first loop of control, including said non-linear probe, to supply the computer with a first KCL correction signal of the quantity of fuel injected and a second control loop, including a second non-linear probe arranged downstream of said catalytic converter to provide a second signal for correcting KRICH of the quantity of fuel injected, said diagnostic device being characterized in that it comprises: - a filtering circuit to which the second KRICH correction signal is applied to supply a filtered signal KRICHp, - a measuring circuit to which the output signal V t from the upstream probe is applied to determine the average value T of the correction period d e the first control loop, and - a logic circuit to determine the good or defective DIAG state of the upstream probe as a function of the values of the filtered signal KRICHp and of the average period T m .
Dans une forme de réalisation de l'invention, le circuit logique détermine que la sonde amont est défectueuse si le signal filtré est supérieur à une valeur maximale ou inférieur à une valeur minimale ou encore si la période moyenne est supérieure à une valeur maximale. Dans une autre forme de réalisation de l'invention, les valeurs maximales et minimales du signal filtré KRICHp sont déterminées par calibration en fonction de la valeur de la période moyenne et sont enregistrées dans une mémoire. Cette mémoire est adressée par la valeur de la période moyenne pour fournir les valeurs maximale et minimale auxquelles est comparée la valeur du signal filtré.In one embodiment of the invention, the logic circuit determines that the upstream probe is defective if the filtered signal is greater than a maximum value or less than a minimum value or even if the average period is greater than a maximum value. In another embodiment of the invention, the maximum and minimum values of the filtered signal KRICHp are determined by calibration as a function of the value of the average period and are recorded in a memory. This memory is addressed by the value of the average period to provide the maximum and minimum values to which the value of the filtered signal is compared.
L'invention concerne également un procédé qui comprend les étapes suivantes : - filtrage du deuxième signal de correction KRICH pour obtenir un signal filtré KRICHp,The invention also relates to a method which comprises the following steps: filtering the second correction signal KRICH to obtain a filtered signal KRICHp,
- calcul de la valeur moyenne Tm de la période du signal de sortie Vamont de la sonde amont,- calculation of the average value T m of the period of the upstream output signal V of the upstream probe,
- comparaison dudit signal filtré KRICHp à deux valeurs maximale KRICHmaχ et minimale KRICHm^n pour déterminer l'état DIAG correct ou défectueux de ladite sonde amont selon que le signal filtré KRICHp est respectivement à l'intérieur des limites définies par les valeurs maximale et minimale ou à l'extérieur desdites limites pour la valeur de la période moyenne τm- D'autres caractéristiques et avantages de la présente invention apparaîtront à la lecture de la description suivante d'un exemple particulier de réalisation, ladite description étant faite en relation avec les dessins joints, dans lesquels :- comparison of said filtered signal KRICHp with two values maximum KRICH maχ and minimum KRICH m ^ n to determine the correct or defective DIAG state of said upstream probe according to whether the filtered signal KRICHp is respectively within the limits defined by the maximum values and minimum or outside of said limits for the value of the average period τ m- Other characteristics and advantages of the present invention will appear on reading the following description of a particular embodiment, said description being made in relation to the accompanying drawings, in which:
- la figure 1 est un schéma fonctionnel d'un système de double boucle de commande de richesse auquel s'applique l'invention ;- Figure 1 is a block diagram of a double wealth control loop system to which the invention applies;
- les figures 2-A et 2-B sont des diagrammes montrant comment s'effectue la correction de richesse avec une seule boucle de contre-réaction comportant une sonde en amont du pot catalytique ; - les figures 3-A et 3-B sont des diagrammes montrant une manière de corriger la richesse en utilisant une deuxième boucle de contre-réaction comportant une sonde en aval du pot catalytique ;- Figures 2-A and 2-B are diagrams showing how the richness correction is carried out with a single feedback loop comprising a probe upstream of the catalytic converter; - Figures 3-A and 3-B are diagrams showing a way of correcting the richness using a second feedback loop comprising a probe downstream of the catalytic converter;
- la figure 4 est un diagramme montrant la manière de filtrer le signal de correction KRICH pour obtenir un signal filtré KRICHp ;- Figure 4 is a diagram showing how to filter the correction signal KRICH to obtain a filtered signal KRICHp;
- la figure 5 est un diagramme montrant un algorithme de calcul de la période moyenne du signal de la sonde amont ; - la figure 6 est un diagramme montrant les courbes qui déterminent les zones de fonctionnement correct ou défectueux de la sonde amont, et- Figure 5 is a diagram showing an algorithm for calculating the average period of the signal from the upstream probe; FIG. 6 is a diagram showing the curves which determine the zones of correct or defective operation of the upstream probe, and
- la figure 7 est un diagramme montrant un algorithme de décision pour déterminer l'état de la sonde amont. Sur la figure 1, un moteur à combustion interne 10 est commandé, de manière connue, par un ordinateur électronique 12. Les gaz d'échappement de ce moteur sont filtrés par un pot d'échappement 14 de type catalytique, duquel ils s'échappent vers l'air libre. Une première sonde 16 est disposée à l'entrée du pot d'échappement et mesure la teneur de l'un des composants principaux des gaz d'échappement, ce composant étant habituellement l'oxygène. Cette sonde est du type non linéaire et est souvent appelée, comme indiqué ci-dessus, sonde "lambda" ou sonde EGO. Cette sonde fournit sur sa borne de sortie un signal électrique Vamont (Figure 2-A) qui est appliqué à un circuit comparateur 18 dans lequel Vaτnon^. est comparé à une tension de seuil vSaιrtθn-t- pour déterminer le signe de Vaιnont par rapport à ce seuil.- Figure 7 is a diagram showing a decision algorithm for determining the state of the upstream probe. In FIG. 1, an internal combustion engine 10 is controlled, in a known manner, by an electronic computer 12. The exhaust gases from this engine are filtered by an exhaust pipe 14 of catalytic type, from which they escape towards the open air. A first probe 16 is disposed at the inlet of the exhaust pipe and measures the content of one of the main components of the exhaust gases, this component usually being oxygen. This probe is of the non-linear type and is often called, as indicated above, "lambda" probe or EGO probe. This probe provides on its output terminal an upstream electrical signal V (Figure 2-A) which is applied to a comparator circuit 18 in which V aτnon ^. is compared with a threshold voltage v S aιrtθn -t- to determine the sign of V aιnont with respect to this threshold.
La valeur du seuil vSaιnont dépend des caractéristiques de la sonde et correspond à la tension de basculement de la sonde lorsque les conditions de stoechiométrie sont remplies.The value of the threshold v S aιnon t depends on the characteristics of the probe and corresponds to the tilting voltage of the probe when the stoichiometric conditions are met.
La borne de sortie du circuit comparateur 18, qui fournit un signal binaire 1 ou 0 , est connectée à la borne d'entrée d'un premier circuit correcteur 20 de régulation de richesse qui est du type proportionnel de gain P et intégral de gain I. Le circuit correcteur 20 fournit un signal KCL qui a la forme représentée par le diagramme de la figure 2-B. C'est ce signal KCL qui est fourni à l'ordinateur 12 pour commander la quantité de carburant à injecter. Ainsi, dès que v am0nt est inférieur à vs amont' ce a signifie que le mélange est pauvre en carburant et qu'il faut augmenter la quantité de carburant. C'est ce qui est réalisé par le saut +P (Figure 2-B) suivi d'une pente positive de valeur I jusqu'au moment où Vamont dépasse VSamont, ce qui signifie que le mélange devient riche en carburant et qu'il faut en diminuer la quantité. Ceci est réalisé par un saut -P suivi d'une pente négative de valeur I. La valeur de correction KCL, fournie par le circuit correcteur 20, est modifiée par un deuxième circuit correcteur 22, qui introduit un terme correcteur KRICH, avant d'être appliquée à l'ordinateur 12. Ce terme correcteur KRICH est déterminé par un circuit 24 à partir d' un signal de sortie Vaval d'une deuxième sonde lambda 26 qui est disposée à la sortie du pot d'échappement catalytique 14. Ce circuit 24 est essentiellement constitué d'un comparateur 28 auquel sont appliqués le signal v ava^ et un signal dit de consigne VCa.,v,,al! et d'un troisième circuit correcteur 30 auquel est appliqué le signal (Vaval - VCaval) fourni par le circuit comparateur 28. Le troisième circuit correcteur 30 est par exemple du type proportionnel et intégral et fournit le signal KRICH qui est appliqué au deuxième circuit correcteur 22.The output terminal of the comparator circuit 18, which provides a binary signal 1 or 0, is connected to the input terminal of a first correction regulator 20 for richness regulation which is of the proportional type of gain P and integral of gain I The corrector circuit 20 supplies a signal KCL which has the form represented by the diagram of FIG. 2-B. It is this signal KCL which is supplied to the computer 12 to control the quantity of fuel to be injected. Thus, as soon as v am0 nt is less than vs am have ' it means that the mixture is poor in fuel and that the quantity of fuel must be increased. This is what is achieved by the jump + P (Figure 2-B) followed by a positive slope of value I until the moment when V upstream exceeds VS upstream , which means that the mixture becomes rich in fuel and that 'the quantity must be reduced. This is achieved by a jump -P followed by a negative slope of value I. The correction value KCL, supplied by the corrector circuit 20, is modified by a second corrector circuit 22, which introduces a corrector term KRICH, before d be applied to the computer 12. This corrector term KRICH is determined by a circuit 24 from an output signal V downstream of a second lambda probe 26 which is disposed at the outlet of the catalytic exhaust 14. This circuit 24 essentially consists of a comparator 28 to which the signal v ava ^ and a so-called reference signal VCa., v ,, al ! and a third corrector circuit 30 to which the signal (V downstream - VC downstream ) supplied by the comparator circuit 28 is applied. The third corrector circuit 30 is for example of the proportional and integral type and supplies the signal KRICH which is applied to the second correction circuit 22.
Le deuxième circuit correcteur 22 peut introduire la correction KRICH de différentes manières dont l'une sera expliquée en relation avec les diagrammes temporels des figures 3-A et 3-B. Ces diagrammes sont des tracés du signal KCL tel que modifié par le deuxième circuit correcteur 22, le signal KCL modifié étant appelé KCL.,,.The second corrector circuit 22 can introduce the KRICH correction in different ways, one of which will be explained in relation to the time diagrams of FIGS. 3-A and 3-B. These diagrams are plots of the KCL signal as modified by the second corrector circuit 22, the modified KCL signal being called KCL. ,,.
Selon les diagrammes des figures 3-A et 3-B, le signal KRICH est appliqué lors des transitions pauvre-riche qui sont détectées par la première sonde, ce qui correspond au flanc descendant du signal KCL. Dans le cas où KRICH > 0 (enrichissement) , le tracé de KCL^ est celui de la figure 3-A tandis que dans le cas où KRICH < 0 (appauvrissement) , le tracé de KCL^ est celui de la figure 3-B.According to the diagrams of FIGS. 3-A and 3-B, the signal KRICH is applied during the lean-to-rich transitions which are detected by the first probe, which corresponds to the falling edge of the signal KCL. In the case where KRICH> 0 (enrichment), the plot of KCL ^ is that of figure 3-A while in the case where KRICH <0 (depletion), the plot of KCL ^ is that of figure 3-B .
Le dispositif de diagnostic de l'état de la sonde 16 comprend les éléments représentés à l'intérieur du rectangle 40 du schéma de la figure 1. Il s'agit d'un filtre 32 auquel est appliqué le signal de sortie KRICH du circuit correcteur 24 de la deuxième boucle ainsi qu'un circuit de calcul 34 de la période moyenne Tm du signal v amcmt de -La sonde amont 16. Les bornes de sortie du filtre 32 et du circuit de calcul 34 sont connectées à un circuit logique 36 qui déterminent l'état bon ou mauvais de la sonde 16 en fonction du signal de sortie KRICHp du filtre 32 et de la valeur Tm de la période moyenne du signal v amθnf Le signal binaire 1 ou O de l'état bon ou mauvais de la sonde 16 apparaît sur la borne de sortie DIAG du circuit logique 36.The device for diagnosing the state of the probe 16 comprises the elements represented inside the rectangle 40 of the diagram in FIG. 1. It is a filter 32 to which the output signal KRICH of the correcting circuit is applied. 24 of the second loop as well as a calculation circuit 34 of the average period T m of the signal v amcm t of - The upstream probe 16. The output terminals of the filter 32 and of the calculation circuit 34 are connected to a logic circuit 36 which determine the good or bad state of the probe 16 as a function of the output signal KRICHp of the filter 32 and of the value T m of the mean period of the signal v amθ nf The binary sig nal 1 or O of the good or bad state of probe 16 appears on the DIAG output terminal of logic circuit 36.
Les informations qui sont fournies par l'ordinateur 12 sont les suivantes :The information which is provided by the computer 12 is as follows:
- le régime moteur REG, - la pression du collecteur d'entrée P,- the engine speed REG, - the pressure of the inlet manifold P,
- l'état de la première boucle : actif ou non,- the state of the first loop: active or not,
- l'état de la deuxième boucle : actif ou non.- the state of the second loop: active or not.
Les circuits 32 et 34 traitent les informations énumérées ci-dessus et n'autorisent le filtrage et le calcul de Tm que si les conditions suivantes sont remplies simultanément :Circuits 32 and 34 process the information listed above and only allow filtering and calculation of T m if the following conditions are met simultaneously:
" REGmin < REG < REGmax "REG min < REG < REG max
- Pmi•n < P r < Prmax- Pmi • n <P r <P r max
Première boucle à l'état actif, - Deuxième boucle à l'état actif,First loop in active state, - Second loop in active state,
REGmin et REGmaχ étant respectivement les valeurs minimale et maximale du régime moteur REG entre lesquelles le diagnostic peut être effectué ; Pmin et pmax étant respectivement les valeurs minimale et maximale de la pression P du collecteur d'entrée entre lesquelles le diagnostic peut être effectué. Le filtrage 32 réalise le calcul de la correction de richesse filtrée KRICHp selon l'algorithme de la figure 4. Ce calcul (étape 42) n'est effectué que si les conditions énumérées ci-dessus sont remplies (étape 44) et, dans ce cas, la richesse moyenne KRICHp est donnée par :REG min and REG maχ being respectively the minimum and maximum values of the engine speed REG between which the diagnosis can be carried out; P m i n and p max being respectively the minimum and maximum values of the pressure P of the inlet manifold between which the diagnosis can be carried out. The filtering 32 performs the calculation of the filtered richness correction KRICHp according to the algorithm of FIG. 4. This calculation (step 42) is only carried out if the conditions listed above are fulfilled (step 44) and, in this case, the average wealth KRICHp is given by:
KRICHp = KRICHp + K(KRICH - KRICHp) avec K un facteur de filtrage compris entre 0 et 1. Le circuit de calcul 34 réalise le calcul de la période moyenne Tm selon l'algorithme de la figure 5. Ce calcul n'est effectué que si les conditions énumérées ci- dessus sont remplies (étape 50) . Ce calcul de la période moyenne T^ consiste à compter les transitions de la tension Vamont d'une valeur inférieure au seuil vsamont ^ une vaj-eur supérieure au seuil pendant un certain intervalle de temps TD et à diviser cet intervalle TD par le nombre N de transitions qui ont été détectées.KRICHp = KRICHp + K (KRICH - KRICHp) with K a filtering factor between 0 and 1. The calculation circuit 34 performs the calculation of the average period T m according to the algorithm of FIG. 5. This calculation is only carried out if the conditions listed above are met (step 50). This calculation of the mean period T ^ is to count the transitions of the voltage V upstream of a value below the threshold vs. upstream ^ a vaj - eur upper threshold for a certain time interval T D and dividing the interval T D by the number N of transitions that have been detected.
L'algorithme de calcul de la période moyenne T de la première boucle est représenté par le diagramme de la figure 5. La première étape (50) consiste à vérifier si les conditions de diagnostic énumérées ci-dessus sont remplies. Si la réponse est "OUI", l'étape de comptage 52 du temps T est démarré, c'est-à-dire que le calcul de la période moyenne T_ commence. Dès que vamont > vsaraont (étape 54) et que l'état ancien ETATA de la sonde correspondant à vamont < vsamont (ETATA = 0) , l'étape 58 consiste à mémoriser ce nouvel état de la sonde par ETATA = 1. L'étape suivante 60 consiste à vérifier si une transition (TRANS = 1) a été déjà détectée auparavant ; en cas de réponse positive, cela signifie qu'une période s'est écoulée et le comptage 62 du nombre N de périodes est augmenté d'une unité. Par la même occasion, le compteur de la durée TD du diagnostic est augmenté de la valeur T du compteur 52. Le calcul 66 de la période moyenne Tm = TD/N est alors effectué avec les nouvelles valeurs de N et TD. L'étape suivante 68 remet à zéro le compteur 52 pour une nouvelle mesure T de la période en cours. Pour que le calcul exposé ci-dessus puisse s'effectuer correctement, il faut que les états suivants soient présents : TRANS = 0, ETATA = 1 et T = 0, ce qui est réalisé par les étapes 72, 74 et 76 en cascade qui sont initialisées par la vérification (étape 50) que les conditions de diagnostic ne sont pas remplies, ce qui est toujours le cas au démarrage du moteur. Ainsi, pour la première mesure de la période, le compteur 52 est à la valeur 0 mais comme ETAT» = 1, le calcul ne peut commencer tant que cet état ne passe pas à ETATA = 0 de manière à être certain de détecter une transition dans le sens voulu. Ceci est obtenu par la détection que v aιrιont < vsamont' aut3uel cas on passe à ETATA = 0 (étape 78) .The algorithm for calculating the average period T of the first loop is represented by the diagram in FIG. 5. The first step (50) consists in checking whether the diagnostic conditions listed above are fulfilled. If the answer is "YES", the step of counting 52 of the time T is started, that is to say that the calculation of the average period T_ begins. As soon as v upstream > vs araont (step 54) and the old state STATE A of the probe corresponding to v upstream <vs upstream (STATE A = 0), step 58 consists in memorizing this new state of the probe by STATE A = 1. The next step 60 consists in checking whether a transition (TRANS = 1) has already been detected before; in the event of a positive response, this means that a period has elapsed and the count 62 of the number N of periods is increased by one. At the same time, the counter for the duration T D of the diagnosis is increased by the value T of the counter 52. The calculation 66 of the average period T m = T D / N is then carried out with the new values of N and T D . The next step 68 resets the counter 52 to zero for a new measurement T of the current period. For the above calculation to be performed correctly, the following states must be present: TRANS = 0, STATE A = 1 and T = 0, which is achieved by steps 72, 74 and 76 in cascade which are initialized by verification (step 50) that the diagnostic conditions are not fulfilled, which is always the case when starting the engine. Thus, for the first measurement of the period, the counter 52 is at the value 0 but as STATE "= 1, the calculation cannot begin until this state does not pass to STATE A = 0 so as to be certain to detect a transition in the desired direction. This is obtained by the detection that v aιrιon t <vs upstream ' aut 3 ue l case we go to STATE A = 0 (step 78).
Au démarrage, TRANS = 0 de sorte que la condition de l'étape 60 n'est pas remplie et il ne peut pas y avoir de calcul de la période. S'il n'en est rien, l'étape 70 impose TRANS = 1, ce qui remet à zéro le compteur 52 par l'étape 68 et un nouveau comptage de T peut commencer. Au démarrage, ETATA = 1 de sorte que la condition de l'étape 56 n'est pas remplie, auquel cas les étapes de l'algorithme sont recommencées.On start-up, TRANS = 0 so that the condition of step 60 is not fulfilled and there cannot be a calculation of the period. If this is not the case, step 70 imposes TRANS = 1, which resets counter 52 by step 68 and a new count of T can begin. At startup, STATE A = 1 so that the condition of step 56 is not fulfilled, in which case the steps of the algorithm are repeated.
Le circuit logique 36 réalise les étapes de l'algorithme de la figure 7 de manière à comparer la valeur de KRICHp à des valeurs qui ont été déterminées comme étant des valeurs limites au-delà desquelles la sonde est considérée comme défectueuse et ceci pour une valeur déterminée Tm de la période moyenne. Ces valeurs limites, appelées KRICHmaχ pour une richesse trop élevée et KRICH-j^ pour un appauvrissement trop important, sont déterminées par une calibration en utilisant une série de sondes dont on connaît les caractéristiques de vieillissement. Cette calibration permet de tracer les courbes KRICHτnaχ et KRICHm^n en fonction de la période Tm (figure 6) , courbes qui peuvent être mémorisées sous la forme de deux tables cartographiques ou d'une seule table regroupant les deux. Ces tables cartographiques peuvent être réalisées par des mémoires qui sont adressées par la valeur de Tm, et les valeurs lues sont KRICrL et KRIŒLj.^ pour la valeur de Tm (figure 6) . La première étape 80 de l'algorithme de diagnostic consiste à comparer la durée TD du calcul de la période T-JJ à une durée minimale TDιn:£n au-dessous de laquelle un diagnostic ne serait pas fiable. Si TD > TDm^n, l'étape suivante 82 consiste à comparer KRICHp à une valeur KRICHιnaχ qui est lue dans la table cartographique 88 donnant KRICH_aχ = SfT-..) . Cette table est adressée par la valeur de Tm pour donner une valeur de KRICHjnaχ qui est comparée à KRICHp. Si la condition n'est pas vérifiée, la sonde est considérée comme défectueuse (étape 92) .The logic circuit 36 performs the steps of the algorithm of FIG. 7 so as to compare the value of KRICHp with values which have been determined to be limit values beyond which the probe is considered to be defective and this for a value determined T m of the mean period. These limit values, called KRICH maχ for an excessively high richness and KRICH- j ^ for an excessive impoverishment, are determined by a calibration using a series of probes whose aging characteristics are known. This calibration makes it possible to plot the KRICH τnaχ and KRICH m ^ n curves as a function of the period T m (FIG. 6), curves which can be stored in the form of two cartographic tables or a single table combining the two. These cartographic tables can be produced by memories which are addressed by the value of T m , and the values read are KRICrL and KRIŒL j . ^ For the value of T m (FIG. 6). The first step 80 of the diagnostic algorithm consists in comparing the duration T D of the calculation of the period T- DD with a minimum duration T Dιn: £ n below which a diagnosis would not be reliable. If T D > T Dm ^ n , the next step 82 consists in comparing KRICHp to a value KRICH ιnaχ which is read in the cartographic table 88 giving KRICH_ aχ = SfT- ..). This table is addressed by the value of T m to give a value of KRICH jnaχ which is compared to KRICHp. If the condition is not checked, the probe is considered to be defective (step 92).
Si la condition est vérifiée, l'étape suivante 84 est de comparer KRICHp à la valeur de KRICH^^ pour T^ telle que lue dans la table 86 dans laquelle sont enregistrées les valeurs de la courbe S(Tm). Si la condition KRICH > KRICH ^ n'est pas vérifiée, la sonde est considérée comme défectueuse (étape 92) avec DIAG = 0. Dans le cas contraire, la sonde est considérée comme correcte (étape 90) avec DIAG = 1.If the condition is satisfied, the next step 84 is to compare KRICHp with the value of KRICH ^^ for T ^ as read in table 86 in which the values of the curve are recorded S (T m ). If the condition KRICH> KRICH ^ is not checked, the probe is considered to be defective (step 92) with DIAG = 0. Otherwise, the probe is considered to be correct (step 90) with DIAG = 1.
Dès que la sonde est considérée comme correcte ou défectueuse, le diagnostic est terminé (étape 94) et un nouveau diagnostic peut être lancé pour obtenir une nouvelle valeur de KRICHp et de Tm. Avec les courbes de la figure 6 qui sont mises sous la forme de tables et en mettant en oeuvre l'algorithme de la figure 7, les sondes qui sont considérées comme mauvaises (DIAG = 0) sont dans la partie hachurée à l'extérieur des deux courbes, les sondes qui sont considérées comme bonnes (DIAG = 1) correspondent à la surface à l'intérieur des courbes.As soon as the probe is considered to be correct or defective, the diagnosis is complete (step 94) and a new diagnosis can be launched to obtain a new value of KRICHp and of T m . With the curves of figure 6 which are put in the form of tables and by implementing the algorithm of figure 7, the probes which are regarded as bad (DIAG = 0) are in the hatched part outside the two curves, the probes which are considered good (DIAG = 1) correspond to the surface inside the curves.
Au lieu des deux courbes de la figure 6, il est possible de se limiter à choisir des seuils fixes pour KRICH'max, KRICH'min et T'maχ et il n'est donc plus nécessaire d'avoir deux tables cartographiques. Dans ce cas simplifié, la valeur de KRICHp est comparée aux deux seuils choisis tandis que la valeur Tm de la valeur moyenne est comparée au seuil T' aχ. Si KRICHp est supérieure à KRICH'maχ, ou inférieure à KRICH'm^n ou supérieure à T'_aχ, la sonde est considérée comme défectueuse. Dans le cas contraire, la sonde est considérée comme bonne. L'algorithme de la figure 7 peut être réalisé sous la forme d'un logiciel ou sous celle de circuits électroniques dans lesquels les étapes de comparaison 80, 82 et 84 seraient réalisées par des comparateurs de nombres. Instead of the two curves in Figure 6, it is possible to limit oneself to choosing fixed thresholds for KRICH ' max , KRICH' min and T ' maχ and it is therefore no longer necessary to have two cartographic tables. In this simplified case, the value of KRICHp is compared with the two selected thresholds while the value T m of the average value is compared with the threshold T ' aχ . If KRICHp is greater than KRICH ' maχ , or less than KRICH' m ^ n or greater than T'_ aχ , the probe is considered to be defective. Otherwise, the probe is considered good. The algorithm of FIG. 7 can be implemented in the form of software or in that of electronic circuits in which the comparison steps 80, 82 and 84 would be performed by number comparators.
Claims
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9512238 | 1995-10-18 | ||
| FR9512238A FR2740173B1 (en) | 1995-10-18 | 1995-10-18 | DEVICE AND METHOD FOR DIAGNOSING THE CONDITION OF A PROBE PROVIDED UPSTREAM OF THE CATALYTIC POT |
| PCT/FR1996/001631 WO1997014876A1 (en) | 1995-10-18 | 1996-10-18 | Device and method for diagnosing the condition of a probe upstream from a catalytic converter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0856098A1 true EP0856098A1 (en) | 1998-08-05 |
| EP0856098B1 EP0856098B1 (en) | 1999-12-22 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP96934934A Expired - Lifetime EP0856098B1 (en) | 1995-10-18 | 1996-10-18 | Device and method for diagnosing the condition of a probe upstream from a catalytic converter |
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| Country | Link |
|---|---|
| US (1) | US6192310B1 (en) |
| EP (1) | EP0856098B1 (en) |
| JP (1) | JP3993891B2 (en) |
| KR (1) | KR100425426B1 (en) |
| DE (1) | DE69605816T2 (en) |
| FR (1) | FR2740173B1 (en) |
| WO (1) | WO1997014876A1 (en) |
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| FR2769985B1 (en) * | 1997-10-17 | 1999-12-31 | Renault | METHOD AND SYSTEM FOR MONITORING THE OPERATION AND AGING OF A LINEAR OXYGEN SENSOR |
| US6311680B1 (en) | 2000-03-21 | 2001-11-06 | Ford Global Technologies, Inc. | Active adaptive bias for closed loop air/fuel control system |
| DE10128969C1 (en) * | 2001-06-15 | 2002-12-12 | Audi Ag | Method for diagnosing guide probe fitted downstream from catalytic converter in system for controlling engine, involves detecting oxygen content in exhaust system for an internal combustion engine. |
| JP4802116B2 (en) * | 2007-02-21 | 2011-10-26 | 日本特殊陶業株式会社 | Gas sensor abnormality diagnosis method, gas sensor abnormality diagnosis device |
| JP4874918B2 (en) * | 2007-10-01 | 2012-02-15 | 日本特殊陶業株式会社 | Gas sensor abnormality diagnosis method, gas sensor abnormality diagnosis device |
| US9606160B2 (en) * | 2014-03-05 | 2017-03-28 | GM Global Technology Operations LLC | Detection of stuck in range sensor and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4747265A (en) * | 1985-12-23 | 1988-05-31 | Toyota Jidosha Kabushiki Kaisha | Double air-fuel ratio sensor system having improved exhaust emission characteristics |
| DE4125154C2 (en) * | 1991-07-30 | 2001-02-22 | Bosch Gmbh Robert | Method and device for lambda probe monitoring in an internal combustion engine |
| DE4139561A1 (en) * | 1991-11-30 | 1993-06-03 | Bosch Gmbh Robert | Monitoring ageing state of oxygen probe connected before catalytic converter for combustion engine - |
| US5337555A (en) * | 1991-12-13 | 1994-08-16 | Mazda Motor Corporation | Failure detection system for air-fuel ratio control system |
| JP3303981B2 (en) * | 1991-12-20 | 2002-07-22 | 株式会社日立製作所 | Diagnosis device for engine exhaust gas purification device |
| JP2978960B2 (en) * | 1992-07-31 | 1999-11-15 | 本田技研工業株式会社 | Oxygen sensor deterioration detection device for internal combustion engine |
| DE4331153C2 (en) * | 1992-09-26 | 2001-02-01 | Volkswagen Ag | Method for obtaining error-specific evaluation criteria of an exhaust gas catalytic converter and a control lambda probe |
| US5656765A (en) * | 1995-06-28 | 1997-08-12 | General Motors Corporation | Air/fuel ratio control diagnostic |
-
1995
- 1995-10-18 FR FR9512238A patent/FR2740173B1/en not_active Expired - Lifetime
-
1996
- 1996-10-18 DE DE69605816T patent/DE69605816T2/en not_active Expired - Lifetime
- 1996-10-18 EP EP96934934A patent/EP0856098B1/en not_active Expired - Lifetime
- 1996-10-18 KR KR10-1998-0702854A patent/KR100425426B1/en not_active IP Right Cessation
- 1996-10-18 US US09/091,237 patent/US6192310B1/en not_active Expired - Lifetime
- 1996-10-18 WO PCT/FR1996/001631 patent/WO1997014876A1/en active IP Right Grant
- 1996-10-18 JP JP51557497A patent/JP3993891B2/en not_active Expired - Fee Related
Non-Patent Citations (1)
| Title |
|---|
| See references of WO9714876A1 * |
Also Published As
| Publication number | Publication date |
|---|---|
| KR100425426B1 (en) | 2004-07-15 |
| JP3993891B2 (en) | 2007-10-17 |
| JP2000508035A (en) | 2000-06-27 |
| KR19990064350A (en) | 1999-07-26 |
| DE69605816T2 (en) | 2000-07-27 |
| WO1997014876A1 (en) | 1997-04-24 |
| FR2740173B1 (en) | 1997-12-05 |
| DE69605816D1 (en) | 2000-01-27 |
| US6192310B1 (en) | 2001-02-20 |
| EP0856098B1 (en) | 1999-12-22 |
| FR2740173A1 (en) | 1997-04-25 |
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