WO2018193174A1 - Method for determining the ageing of a catalytic converter of a motor vehicle exhaust line - Google Patents

Method for determining the ageing of a catalytic converter of a motor vehicle exhaust line Download PDF

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Publication number
WO2018193174A1
WO2018193174A1 PCT/FR2018/050610 FR2018050610W WO2018193174A1 WO 2018193174 A1 WO2018193174 A1 WO 2018193174A1 FR 2018050610 W FR2018050610 W FR 2018050610W WO 2018193174 A1 WO2018193174 A1 WO 2018193174A1
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WO
WIPO (PCT)
Prior art keywords
catalyst
osc
oxygen storage
storage capacity
dec
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PCT/FR2018/050610
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French (fr)
Inventor
Charles LEMAITRE
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Psa Automobiles Sa
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Publication date
Application filed by Psa Automobiles Sa filed Critical Psa Automobiles Sa
Priority to EP18714576.8A priority Critical patent/EP3612723A1/en
Publication of WO2018193174A1 publication Critical patent/WO2018193174A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • F01N11/007—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
    • F01N2550/02—Catalytic activity of catalytic converters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/02—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor
    • F01N2560/025—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor for measuring or detecting O2, e.g. lambda sensors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/14—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics having more than one sensor of one kind
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/04—Methods of control or diagnosing
    • F01N2900/0416—Methods of control or diagnosing using the state of a sensor, e.g. of an exhaust gas sensor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/14—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust gas
    • F01N2900/1411—Exhaust gas flow rate, e.g. mass flow rate or volumetric flow rate
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
    • F01N2900/1602—Temperature of exhaust gas apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
    • F01N2900/1624—Catalyst oxygen storage capacity
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Definitions

  • the present invention relates to a method for determining the aging of a motor vehicle exhaust system catalyst.
  • the catalyst is made based on a material with reversible oxygen storage properties as a function of the richness of the exhaust gases.
  • the catalyst has an oxygen storage capacity, called “OSC” for "Oxygen Storage Capacity” in English. It allows to store the oxygen when the engine is operating in a lean regime (air / fuel ratio higher than 1) to restore it in rich mode (air / fuel ratio less than or equal to 1).
  • the catalyst contributes to the oxidation of carbon monoxide (CO) and unburned hydrocarbons (HC) and the reduction of nitrogen oxides (NOx).
  • the oxygen storage capacity of the catalyst is an indicator of its aging because the more the catalyst ages, the less it is capable of storing oxygen.
  • a strategy consists in measuring the oxygen storage capacity of the catalyst (image of the amount of active compounds). To determine this oxygen storage capacity, the strategy first empties the catalyst of its oxygen through a rich combustion, then fills it with a poor combustion. When an oxygen sensor located downstream of the catalyst detects oxygen, it means that the catalyst has reached its storage capacity.
  • the oxygen storage capacity of the catalyst OSC_Bru may be different for the same aging as a function respectively of the catalyst temperature, as shown in Figure 1a, and the flow rate Deb of the exhaust gas expressed in kilograms per second, as shown in Figure 1b. For this reason, a correction factor dependent on these two parameters is applied to make this raw storage capacity OSC_Bru constant, as shown in Figures 2a and 2b which represent a corrected storage capacity OSC_Corr.
  • the problem with this strategy is that the variation of the oxygen storage capacity is non-linear as a function of aging. Thus, a corrective factor is not valid only at a given moment for the catalyst.
  • FIG. 3a thus illustrates the evolution of raw oxygen storage capacities as a function of the temperature respectively for a new catalyst (see OSC_Bru_N), aged (see OSC_Bru_V), and failed (see OSC_Bru_OBD).
  • OSC_Bru_N new catalyst
  • OSC_Bru_V aged
  • OSC_Bru_OBD failed
  • 3b shows that a given corrective factor is adapted to correct the storage capacity of a defective catalyst (see curve OSC_Corr_OBD substantially constant) but is not adapted to correct the oxygen storage capacities of a new catalyst (see OSC_Corr_N) and aged (see OSC_Corr_V) which present a great dispersion.
  • the invention aims to effectively overcome this disadvantage by providing a method for determining the aging of a catalyst equipping an exhaust line, including a motor vehicle, the exhaust line being equipped with oxygen sensors upstream and downstream of the catalyst,
  • This process comprises:
  • the invention thus provides a gain in accuracy of the aging calculation of the catalyst, which reduces the pollutant emissions according to the driving profile.
  • the fact of not switching too early on an engine setting "aged” to compensate for the loss of efficiency of the catalyst makes it possible to gain in consumption.
  • the fact of not tipping too late on an engine setting "aged” ensures compliance with anti-pollution standards.
  • the method comprises a step of comparing the measured raw oxygen storage capacity with decision thresholds. corresponding to different states of the catalyst, the corrective factor being selected according to the previous comparison.
  • a first decision threshold corresponding to a new catalyst state and a second decision threshold corresponding to an aged catalyst state are defined.
  • the raw oxygen storage capacity in the case where the raw oxygen storage capacity is greater than the first decision threshold corresponding to the new catalyst state, then the raw oxygen storage capacity is corrected with a first factor. patch corresponding to a new catalyst.
  • the raw oxygen storage capacity in the case where the raw oxygen storage capacity is less than the first decision threshold corresponding to the new catalyst state and greater than the second decision threshold corresponding to the aged catalyst state. then the raw oxygen storage capacity is corrected with a second corrective factor corresponding to an aged catalyst.
  • the raw oxygen storage capacity in the case where the raw oxygen storage capacity is less than the second decision threshold corresponding to the aged catalyst state, the raw oxygen storage capacity is corrected with a third corrective factor. corresponding to a failed catalyst state.
  • the decision thresholds are obtained from a map that is a function of the flow of the exhaust gas and the catalyst temperature.
  • the method comprises:
  • the measurement of the raw oxygen storage capacity as well as the corrected oxygen storage capacity and the decision thresholds are obtained according to the following steps:
  • Figures 1a and 1b are graphical representations illustrating the evolution of a raw oxygen storage capacity of a catalyst as a function respectively of a catalyst temperature and a flow rate of exhaust gas;
  • FIGS. 2a and 2b are graphical representations illustrating the evolution of the oxygen storage capacity of Figures 1a and 1b corrected by a correction factor
  • FIG. 3a is a graphical representation illustrating the evolution of a raw oxygen storage capacity of the catalyst as a function of the catalyst temperature and for different catalyst states, namely a new catalyst, a aged catalyst, and a failed catalyst;
  • FIG. 3b is a graphical representation illustrating the dispersion between the oxygen storage capacities corrected by the same corrective factor for different catalyst states, namely a new catalyst, an aged catalyst, and a defective catalyst. ;
  • Figure 4 is a schematic representation of an architecture of an exhaust line of an internal combustion engine implementing the catalyst aging determination method according to the present invention
  • FIG. 5 is a functional diagram of the different steps of the method for determining the aging of the catalyst according to the present invention.
  • FIG. 6 is a graphical representation illustrating the evolution of a corrected oxygen storage capacity by a corrective factor chosen as a function of the state of the catalyst.
  • Figure 4 schematically shows a portion of an exhaust line 1 collecting the exhaust gas of an internal combustion engine 2 gasoline type equipping a motor vehicle.
  • the exhaust line 1 comprises a catalyst 3 arranged upstream of a particulate filter 4.
  • the catalyst 3 and the particulate filter 4 are grouped in the same casing 5 connecting to the rest of the line 1 by its ends (the Figure represents only half of the envelope 5 to make visible the catalyst 3 and the particulate filter 4).
  • the catalyst 3 is made of a material with reversible oxygen storage properties as a function of the richness of the exhaust gas.
  • Catalyst 3 has an oxygen storage capacity, called “OSC” for "Oxygen Storage Capacity". It allows the oxygen to be stored when the engine 2 is running at a lean speed (air / fuel ratio greater than 1) in order to restore it to a rich regime (air / fuel ratio less than or equal to 1).
  • Catalyst 3 contributes to the oxidation of carbon monoxide (CO) and unburnt hydrocarbons (HC) and the reduction of nitrogen oxides (NOx).
  • the oxygen storage capacity of the catalyst 3 is an indicator of its aging because the older the catalyst 3, the less it is capable of storing oxygen.
  • the exhaust line 1 is also provided with two oxygen probes 6, 7 commonly called lambda probes, respectively disposed upstream and downstream of the catalyst 3.
  • These probes 6, 7 of known type may take the form of linear or stoichiometric type probe.
  • the engine computer detects favorable conditions to achieve the measurement of the oxygen storage OSC_Bru raw capacity of the catalyst 3.
  • the temperature of the catalyst 3 must be high enough for the chemical reactions to occur.
  • the flow rate of the gas passing through the catalyst 3 must not be too high to allow the reagents time to store the oxygen.
  • the realization of the diagnostics of the oxygen probes 6, 7 must be carried out so as not to encounter interference in the wealth niches.
  • a good stability of richness is needed for the precision of the calculation of the oxygen in the exhaust gases.
  • Other conditions, such as engine speed, load, the speed of the vehicle can be taken into account to exclude particular life situations in technical control for example.
  • a step 102 the catalyst 3 is emptied of its oxygen by triggering a rich combustion, which allows to start the measurement in a step 103.
  • the catalyst 3 is then filled with oxygen through the triggering of a lean combustion and the calculation of the OSC_Bru oxygen storage capacity of the catalyst 3 is carried out in a step 104.
  • the oxygen storage capacities corrected OSC_Corr_N, OSC_Corr_V, OSC_Corr_OBD are calculated respectively for corrective factors dependent on the temperature of the catalyst 3 and the flow rate of the corresponding exhaust gases to different typical states of the catalyst 3, namely a first corrective factor corresponding to a catalyst 3 considered as new OSC_Corr_N, a second correction factor corresponding to a catalyst 3 considered aged OSC_Corr_V, and a third corrective factor corresponding to a catalyst 3 considered as failed OSC_Corr_OBD.
  • the corrective factor is therefore adjusted according to whether it is considered that the catalyst 3 is classified in category nine or aged or defective.
  • the OSC_Bru measurement is stopped in a step 106.
  • the process therefore chooses the capacity corrected oxygen storage OSC_Corr_N, OSC_Corr_V, OSC_Corr_OBD to be taken into account in the calculation of catalyst aging 3.
  • OSC_Corr_N, OSC_Corr_V, OSC_Corr_OBD the capacity corrected oxygen storage OSC_Corr_N, OSC_Corr_V, OSC_Corr_OBD to be taken into account in the calculation of catalyst aging 3.
  • the measured raw oxygen storage capacity OSC_Bru is compared, in a step 107, with decision thresholds S_Dec_N, S_Dec_V corresponding to different states of the catalyst 3.
  • a first decision threshold S_Dec_N corresponding to a catalyst is thus defined. 3 nine and a second decision threshold S_Dec_V corresponding to an aged catalyst 3.
  • the decision thresholds S_Dec_N, S_Dec_V are obtained from a map Cart_Dec which is a function of the flow rate Deb of the exhaust gas and the temperature of the catalyst 3. These decision thresholds S_Dec_N, S_Dec_V, as for the storage capacity, can be calculated during step 104, which makes it possible to have an evolution of these during the measurement in the event of a change of operating point, or be chosen at the end of the measurement, which makes it necessary to measure the raw OSC_Bru oxygen storage capacity at a single operating point.
  • the raw oxygen storage capacity OSC_Bru is greater than the first decision threshold S_Dec_N corresponding to a new catalyst 3 then the raw oxygen storage capacity OSC_Bru is corrected with a corrective factor corresponding to the catalyst state 3 new (see OSC_Corr_N).
  • the raw oxygen storage capacity OSC_Bru is less than the first decision threshold S_Dec_N and greater than the second decision threshold S_Dec_V corresponding to a catalyst 3 aged then the raw oxygen storage capacity OSC_Bru is corrected with a corrective factor corresponding to the aged catalyst state 3 (see OSC_Corr_V).
  • the raw oxygen storage capacity OSC_Bru is lower than the second decision threshold S_Dec_V then the raw oxygen storage capacity OSC_Bru is corrected with a correction factor corresponding to the failed catalyst state 3 (see OSC_Corr_OBD). ).
  • a corrected oxygen storage capacity OSC_Corr is then determined with the corrective factor selected as a function of the preceding comparison in a step 108 which may occur at the same time as step 104.
  • FIG. 6 shows that the process according to the invention makes it possible to obtain a constant corrected oxygen storage capacity whatever the state of the catalyst 3 (see curve OSC_Corr_N for a new catalyst, OSC_Corr_V for an aged catalyst, OSC_Corr_OBD for a defective catalyst).
  • the engine computer can then determine the aging of the catalyst 3, in a step 109, depending on the corrected oxygen storage capacity thus determined.
  • the aging of a catalyst 3 is expressed in kilometers. This mileage is not that of the vehicle because the driving profile, among other things, degrades more or less rapidly catalyst 3.
  • the calculation consists in characterizing the raw oxygen storage capacity OSC_Bru of a new catalyst 3, a catalyst 3 aged according to a precise range representing the average profile of a driver having traveled 100,000 kilometers, and a Catalyst 3 defaults in a range until the pollutant emissions of the vehicle exceed the failure thresholds established by a given regulation.
  • a table of correspondence between raw oxygen storage capacity OSC_Bru and mileage of the catalyst 3 is integrated in the engine calculator to convert the raw oxygen storage capacity OSC_Bru in kilometer.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

The invention relates mainly to a method for determining the ageing of a catalytic converter equipping an exhaust line, in particular of a motor vehicle, said exhaust line being equipped with oxygen probes upstream and downstream from the catalytic converter, characterised in that said method includes: - a step (103) of measuring a raw oxygen storage capacity of the catalytic converter at a given time; - a step of determining a state of the catalytic converter as a function of the measurement of the raw oxygen storage capacity; - a step (108) of determining a corrected oxygen storage capacity from a corrective factor which depends on a temperature of the catalytic converter, a flow rate of the exhaust gases, and the state of the catalytic converter; and - a step of determining (109) the ageing of the catalytic converter as a function of the corrected oxygen storage capacity.

Description

PROCEDE DE DETERMINATION DU VIEILLISSEMENT D'UN CATALYSEUR DE LIGNE D'ECHAPPEMENT DE VEHICULE  METHOD FOR DETERMINING THE AGING OF A VEHICLE EXHAUST LINE CATALYST
AUTOMOBILE  AUTOMOBILE
[0001 ] La présente invention porte sur un procédé de détermination du vieillissement d'un catalyseur de ligne d'échappement de véhicule automobile. The present invention relates to a method for determining the aging of a motor vehicle exhaust system catalyst.
[0002] On connaît des lignes d'échappement de moteur à combustion interne à essence munies d'un catalyseur disposé en amont d'un filtre à particules. Ce catalyseur est réalisé à base d'un matériau aux propriétés de stockage réversible d'oxygène en fonction de la richesse des gaz d'échappement. Le catalyseur présente une capacité de stockage en oxygène, dite "OSC" pour "Oxygen Storage Capacity" en anglais. Il permet de stocker l'oxygène lorsque le moteur fonctionne en régime pauvre (rapport air/carburant supérieur à 1 ) pour le restituer en régime riche (rapport air/carburant inférieur ou égal à 1 ). Le catalyseur contribue à assurer l'oxydation du monoxyde de carbone (CO) et des hydrocarbures imbrûlés (HC) et la réduction des oxydes d'azote (NOx). La capacité de stockage en oxygène du catalyseur est un indicateur de son vieillissement car plus le catalyseur vieillit, moins il est capable de stocker de l'oxygène. There are known gasoline internal combustion engine exhaust lines provided with a catalyst arranged upstream of a particulate filter. This catalyst is made based on a material with reversible oxygen storage properties as a function of the richness of the exhaust gases. The catalyst has an oxygen storage capacity, called "OSC" for "Oxygen Storage Capacity" in English. It allows to store the oxygen when the engine is operating in a lean regime (air / fuel ratio higher than 1) to restore it in rich mode (air / fuel ratio less than or equal to 1). The catalyst contributes to the oxidation of carbon monoxide (CO) and unburned hydrocarbons (HC) and the reduction of nitrogen oxides (NOx). The oxygen storage capacity of the catalyst is an indicator of its aging because the more the catalyst ages, the less it is capable of storing oxygen.
[0003] Ainsi, afin de connaître l'état de vieillissement du catalyseur, une stratégie consiste à mesurer la capacité de stockage en oxygène du catalyseur (image de la quantité de composés actifs). Pour déterminer cette capacité de stockage en oxygène, la stratégie vide d'abord le catalyseur de son oxygène grâce à une combustion riche, puis le remplit avec une combustion pauvre. Lorsqu'une sonde à oxygène située en aval du catalyseur détecte de l'oxygène, cela signifie que le catalyseur a atteint sa capacité de stockage. Thus, in order to know the state of aging of the catalyst, a strategy consists in measuring the oxygen storage capacity of the catalyst (image of the amount of active compounds). To determine this oxygen storage capacity, the strategy first empties the catalyst of its oxygen through a rich combustion, then fills it with a poor combustion. When an oxygen sensor located downstream of the catalyst detects oxygen, it means that the catalyst has reached its storage capacity.
[0004] La capacité de stockage en oxygène du catalyseur OSC_Bru peut être différente pour un même vieillissement en fonction respectivement de la température du catalyseur, comme cela est illustré par la figure 1 a, et du débit Deb des gaz d'échappement exprimé en kilogramme par seconde, comme cela est illustré par la figure 1 b. Pour cette raison, un facteur correctif dépendant de ces deux paramètres est appliqué pour rendre cette capacité brute de stockage OSC_Bru constante, tel que cela est illustré sur les figures 2a et 2b qui représentent une capacité de stockage corrigée OSC_Corr. [0005] Le problème de cette stratégie est que la variation de la capacité de stockage en oxygène est non linéaire en fonction du vieillissement. Ainsi, un facteur correctif n'est valable qu'à un instant donné pour le catalyseur. Un même facteur correctif amène donc de la dispersion pour d'autres vieillissements, ce qui rend difficile l'adaptation des réglages du moteur à combustion interne pour tenir compte de la dégradation des performances du système de post-traitement. [0006] La figure 3a illustre ainsi l'évolution de capacités brutes de stockage en oxygène en fonction de la température respectivement pour un catalyseur neuf (cf. OSC_Bru_N), vieilli (cf. OSC_Bru_V), et défaillant (cf. OSC_Bru_OBD). La figure 3b montre qu'un facteur correctif donné est adapté pour corriger la capacité de stockage d'un catalyseur défaillant (cf. courbe OSC_Corr_OBD sensiblement constante) mais n'est pas adapté pour corriger les capacités de stockage en oxygène d'un catalyseur neuf (cf. OSC_Corr_N) et vieilli (cf. OSC_Corr_V) qui présentent une grande dispersion. The oxygen storage capacity of the catalyst OSC_Bru may be different for the same aging as a function respectively of the catalyst temperature, as shown in Figure 1a, and the flow rate Deb of the exhaust gas expressed in kilograms per second, as shown in Figure 1b. For this reason, a correction factor dependent on these two parameters is applied to make this raw storage capacity OSC_Bru constant, as shown in Figures 2a and 2b which represent a corrected storage capacity OSC_Corr. The problem with this strategy is that the variation of the oxygen storage capacity is non-linear as a function of aging. Thus, a corrective factor is not valid only at a given moment for the catalyst. The same corrective factor therefore brings dispersion for other aging, which makes it difficult to adapt the settings of the internal combustion engine to take account of the degradation of the performance of the post-processing system. [0006] FIG. 3a thus illustrates the evolution of raw oxygen storage capacities as a function of the temperature respectively for a new catalyst (see OSC_Bru_N), aged (see OSC_Bru_V), and failed (see OSC_Bru_OBD). FIG. 3b shows that a given corrective factor is adapted to correct the storage capacity of a defective catalyst (see curve OSC_Corr_OBD substantially constant) but is not adapted to correct the oxygen storage capacities of a new catalyst (see OSC_Corr_N) and aged (see OSC_Corr_V) which present a great dispersion.
[0007] L'invention vise à remédier efficacement à cet inconvénient en proposant un procédé de détermination du vieillissement d'un catalyseur équipant une ligne d'échappement, notamment de véhicule automobile, la ligne d'échappement étant équipée de sondes à oxygène en amont et en aval du catalyseur, The invention aims to effectively overcome this disadvantage by providing a method for determining the aging of a catalyst equipping an exhaust line, including a motor vehicle, the exhaust line being equipped with oxygen sensors upstream and downstream of the catalyst,
Ce procédé comporte: This process comprises:
- une étape de mesure d'une capacité brute de stockage en oxygène du catalyseur à un instant donné,  a step of measuring a raw oxygen storage capacity of the catalyst at a given instant,
- une étape de détermination d'un état du catalyseur en fonction de la mesure de la capacité brute de stockage en oxygène,  a step of determining a state of the catalyst as a function of the measurement of the raw oxygen storage capacity,
- une étape de détermination d'une capacité de stockage en oxygène corrigée à partir d'un facteur correctif qui dépend d'une température du catalyseur, d'un débit des gaz d'échappement, et de l'état du catalyseur, et  a step of determining a corrected oxygen storage capacity from a corrective factor which depends on a catalyst temperature, a flow rate of the exhaust gas, and the state of the catalyst, and
- une étape de détermination du vieillissement du catalyseur en fonction de la capacité de stockage en oxygène corrigée.  a step of determining the aging of the catalyst as a function of the corrected oxygen storage capacity.
[0008] L'invention permet ainsi d'obtenir un gain en précision du calcul de vieillissement du catalyseur, ce qui permet de réduire les émissions polluantes en fonction du profil de conduite. Par ailleurs, le fait de ne pas basculer trop tôt sur un réglage moteur "vieilli" pour compenser la perte d'efficacité du catalyseur permet de gagner en consommation. En outre, le fait de ne pas basculer trop tard sur un réglage moteur "vieilli" permet de garantir le respect des normes anti-pollution. The invention thus provides a gain in accuracy of the aging calculation of the catalyst, which reduces the pollutant emissions according to the driving profile. In addition, the fact of not switching too early on an engine setting "aged" to compensate for the loss of efficiency of the catalyst makes it possible to gain in consumption. In addition, the fact of not tipping too late on an engine setting "aged" ensures compliance with anti-pollution standards.
[0009] Selon une mise en œuvre, le procédé comporte une étape de comparaison de la capacité brute de stockage en oxygène mesurée avec des seuils de décision correspondants à différents états du catalyseur, le facteur correctif étant sélectionné en fonction de la comparaison précédente. According to one embodiment, the method comprises a step of comparing the measured raw oxygen storage capacity with decision thresholds. corresponding to different states of the catalyst, the corrective factor being selected according to the previous comparison.
[0010] Selon une mise en œuvre, on définit un premier seuil de décision correspondant à un état de catalyseur neuf et un deuxième seuil de décision correspondant à un état de catalyseur vieilli. According to one embodiment, a first decision threshold corresponding to a new catalyst state and a second decision threshold corresponding to an aged catalyst state are defined.
[001 1 ] Selon une mise en œuvre, dans le cas où la capacité brute de stockage en oxygène est supérieure au premier seuil de décision correspondant à l'état de catalyseur neuf alors la capacité brute de stockage en oxygène est corrigée avec un premier facteur correctif correspondant à un catalyseur neuf. [0012] Selon une mise en œuvre, dans le cas où la capacité brute de stockage en oxygène est inférieure au premier seuil de décision correspondant à l'état de catalyseur neuf et supérieure au deuxième seuil de décision correspondant à l'état de catalyseur vieilli alors la capacité brute de stockage en oxygène est corrigée avec un deuxième facteur correctif correspondant à un catalyseur vieilli. [0013] Selon une mise en œuvre, dans le cas où la capacité brute de stockage en oxygène est inférieure au deuxième seuil de décision correspondant à l'état de catalyseur vieilli alors la capacité brute de stockage en oxygène est corrigée avec un troisième facteur correctif correspondant à un état de catalyseur défaillant. According to one embodiment, in the case where the raw oxygen storage capacity is greater than the first decision threshold corresponding to the new catalyst state, then the raw oxygen storage capacity is corrected with a first factor. patch corresponding to a new catalyst. According to one embodiment, in the case where the raw oxygen storage capacity is less than the first decision threshold corresponding to the new catalyst state and greater than the second decision threshold corresponding to the aged catalyst state. then the raw oxygen storage capacity is corrected with a second corrective factor corresponding to an aged catalyst. According to one embodiment, in the case where the raw oxygen storage capacity is less than the second decision threshold corresponding to the aged catalyst state, the raw oxygen storage capacity is corrected with a third corrective factor. corresponding to a failed catalyst state.
[0014] Selon une mise en œuvre, les seuils de décision sont obtenus à partir d'une cartographie qui est fonction du débit des gaz d'échappement et de la température du catalyseur. According to one implementation, the decision thresholds are obtained from a map that is a function of the flow of the exhaust gas and the catalyst temperature.
[0015] Selon une mise en œuvre, le procédé comporte: According to one embodiment, the method comprises:
- une étape de calcul préalable de différentes capacités de stockage en oxygène corrigées avec un ensemble de facteurs correctifs correspondant à différents états du catalyseur, et - une étape de sélection de la capacité de stockage en oxygène corrigée en fonction de la comparaison entre la capacité brute de stockage en oxygène mesurée et les seuils de décision correspondants à différents états du catalyseur.  a step of prior calculation of different oxygen storage capacities corrected with a set of correction factors corresponding to different states of the catalyst, and a step of selecting the oxygen storage capacity corrected as a function of the comparison between the gross capacity. measured oxygen storage and the decision thresholds corresponding to different states of the catalyst.
[0016] Selon une mise en œuvre, la mesure de la capacité brute de stockage en oxygène ainsi que la capacité de stockage en oxygène corrigée et les seuils de décision sont obtenus suivant les étapes suivantes: According to one embodiment, the measurement of the raw oxygen storage capacity as well as the corrected oxygen storage capacity and the decision thresholds are obtained according to the following steps:
- une étape de vidage du catalyseur en oxygène par déclenchement d'une combustion riche, - une étape de commencement de la mesure, a step of emptying the oxygen catalyst by triggering a rich combustion, a step of beginning of the measurement,
- une étape de remplissage du catalyseur en oxygène par déclenchement d'une combustion pauvre, et  a step of filling the catalyst with oxygen by triggering a poor combustion, and
- une étape d'arrêt de la mesure lorsque la sonde à oxygène en aval du catalyseur détecte de l'oxygène.  a step of stopping the measurement when the oxygen sensor downstream of the catalyst detects oxygen.
[0017] L'invention sera mieux comprise à la lecture de la description qui suit et à l'examen des figures qui l'accompagnent. Ces figures ne sont données qu'à titre illustratif mais nullement limitatif de l'invention. The invention will be better understood from reading the following description and examining the figures that accompany it. These figures are given for illustrative but not limiting of the invention.
[0018] Les figures 1 a et 1 b, déjà décrites, sont des représentations graphiques illustrant l'évolution d'une capacité brute de stockage en oxygène d'un catalyseur en fonction respectivement d'une température du catalyseur et d'un débit des gaz d'échappement; Figures 1a and 1b, already described, are graphical representations illustrating the evolution of a raw oxygen storage capacity of a catalyst as a function respectively of a catalyst temperature and a flow rate of exhaust gas;
[0019] Les figures 2a et 2b, déjà décrites, sont des représentations graphiques illustrant l'évolution de la capacité de stockage en oxygène des figures 1 a et 1 b corrigée par un facteur correctif; [0020] La figure 3a, déjà décrite, est une représentation graphique illustrant l'évolution d'une capacité brute de stockage en oxygène du catalyseur en fonction de la température du catalyseur et pour différents états du catalyseur, à savoir un catalyseur neuf, un catalyseur vieilli, et un catalyseur défaillant; Figures 2a and 2b, already described, are graphical representations illustrating the evolution of the oxygen storage capacity of Figures 1a and 1b corrected by a correction factor; FIG. 3a, already described, is a graphical representation illustrating the evolution of a raw oxygen storage capacity of the catalyst as a function of the catalyst temperature and for different catalyst states, namely a new catalyst, a aged catalyst, and a failed catalyst;
[0021 ] La figure 3b, déjà décrite, est une représentation graphique illustrant la dispersion entre les capacités de stockage en oxygène corrigées par un même facteur correctif pour différents états du catalyseur, à savoir un catalyseur neuf, un catalyseur vieilli, et un catalyseur défaillant; FIG. 3b, already described, is a graphical representation illustrating the dispersion between the oxygen storage capacities corrected by the same corrective factor for different catalyst states, namely a new catalyst, an aged catalyst, and a defective catalyst. ;
[0022] La figure 4 est une représentation schématique d'une architecture d'une ligne d'échappement d'un moteur à combustion interne mettant en œuvre le procédé de détermination du vieillissement du catalyseur selon la présente invention; Figure 4 is a schematic representation of an architecture of an exhaust line of an internal combustion engine implementing the catalyst aging determination method according to the present invention;
[0023] La figure 5 est un diagramme fonctionnel des différentes étapes du procédé de détermination du vieillissement du catalyseur selon la présente invention; FIG. 5 is a functional diagram of the different steps of the method for determining the aging of the catalyst according to the present invention;
[0024] La figure 6 est une représentation graphique illustrant l'évolution d'une capacité de stockage en oxygène corrigée par un facteur correctif choisi en fonction de l'état du catalyseur. [0025] La figure 4 représente schématiquement une partie d'une ligne d'échappement 1 collectant les gaz d'échappement d'un moteur à combustion interne 2 de type essence équipant un véhicule automobile. La ligne d'échappement 1 comporte un catalyseur 3 disposé en amont d'un filtre à particules 4. Le catalyseur 3 et le filtre à particules 4 sont regroupés dans une même enveloppe 5 se raccordant au reste de la ligne 1 par ses extrémités (la figure ne représente que la moitié de l'enveloppe 5 pour rendre visibles le catalyseur 3 et le filtre à particules 4). FIG. 6 is a graphical representation illustrating the evolution of a corrected oxygen storage capacity by a corrective factor chosen as a function of the state of the catalyst. [0025] Figure 4 schematically shows a portion of an exhaust line 1 collecting the exhaust gas of an internal combustion engine 2 gasoline type equipping a motor vehicle. The exhaust line 1 comprises a catalyst 3 arranged upstream of a particulate filter 4. The catalyst 3 and the particulate filter 4 are grouped in the same casing 5 connecting to the rest of the line 1 by its ends (the Figure represents only half of the envelope 5 to make visible the catalyst 3 and the particulate filter 4).
[0026] Le catalyseur 3 est réalisé à base d'un matériau aux propriétés de stockage réversible d'oxygène en fonction de la richesse des gaz d'échappement. Le catalyseur 3 présente une capacité de stockage en oxygène, dite "OSC" pour "Oxygen Storage Capacity" en anglais. Il permet de stocker l'oxygène lorsque le moteur 2 fonctionne en régime pauvre (rapport air/carburant supérieur à 1 ) pour le restituer en régime riche (rapport air/carburant inférieur ou égal à 1 ). Le catalyseur 3 contribue à assurer l'oxydation du monoxyde de carbone (CO) et des hydrocarbures imbrûlés (HC) et la réduction des oxydes d'azote (NOx). La capacité de stockage en oxygène du catalyseur 3 est un indicateur de son vieillissement car plus le catalyseur 3 vieillit, moins il est capable de stocker de l'oxygène. The catalyst 3 is made of a material with reversible oxygen storage properties as a function of the richness of the exhaust gas. Catalyst 3 has an oxygen storage capacity, called "OSC" for "Oxygen Storage Capacity". It allows the oxygen to be stored when the engine 2 is running at a lean speed (air / fuel ratio greater than 1) in order to restore it to a rich regime (air / fuel ratio less than or equal to 1). Catalyst 3 contributes to the oxidation of carbon monoxide (CO) and unburnt hydrocarbons (HC) and the reduction of nitrogen oxides (NOx). The oxygen storage capacity of the catalyst 3 is an indicator of its aging because the older the catalyst 3, the less it is capable of storing oxygen.
[0027] La ligne d'échappement 1 est également munie de deux sondes à oxygène 6, 7 appelées couramment sondes lambda, disposées respectivement en amont et en aval de du catalyseur 3. Ces sondes 6, 7 de type connu pourront prendre la forme de sonde de type linéaire ou stœchiométrique. The exhaust line 1 is also provided with two oxygen probes 6, 7 commonly called lambda probes, respectively disposed upstream and downstream of the catalyst 3. These probes 6, 7 of known type may take the form of linear or stoichiometric type probe.
[0028] On décrit ci-après, en référence avec les figures 5 et 6, les étapes du procédé de détermination du vieillissement du catalyseur 3 selon la présente invention. Ces étapes pourront par exemple être mises en œuvre par le calculateur moteur du véhicule qui comporte une mémoire stockant des instructions logicielles à cet effet. [0029] Dans une étape 101 , le calculateur moteur détecte des conditions favorables pour réaliser la mesure de la capacité brute de stockage en oxygène OSC_Bru du catalyseur 3. Il existe quatre principales conditions. Tout d'abord, la température du catalyseur 3 doit être assez élevée pour que les réactions chimiques puissent se produire. Ensuite, le débit des gaz traversant le catalyseur 3 ne doit pas être trop élevé pour laisser le temps aux réactifs de stocker l'oxygène. Puis, la réalisation des diagnostics des sondes à oxygène 6, 7 doit être réalisée pour ne pas rencontrer d'interférences dans les créneaux de richesse. Enfin, pour réaliser la mesure, il faut une bonne stabilité de richesse pour la précision du calcul de l'oxygène dans les gaz d'échappement. D'autres conditions, comme le régime moteur, la charge, la vitesse du véhicule peuvent être prises en compte pour exclure des situations de vie particulières en contrôle technique par exemple. Hereinafter, with reference to FIGS. 5 and 6, the steps of the method for determining the aging of the catalyst 3 according to the present invention are described. These steps may for example be implemented by the vehicle engine computer which includes a memory storing software instructions for this purpose. In a step 101, the engine computer detects favorable conditions to achieve the measurement of the oxygen storage OSC_Bru raw capacity of the catalyst 3. There are four main conditions. First, the temperature of the catalyst 3 must be high enough for the chemical reactions to occur. Then, the flow rate of the gas passing through the catalyst 3 must not be too high to allow the reagents time to store the oxygen. Then, the realization of the diagnostics of the oxygen probes 6, 7 must be carried out so as not to encounter interference in the wealth niches. Finally, to achieve the measurement, a good stability of richness is needed for the precision of the calculation of the oxygen in the exhaust gases. Other conditions, such as engine speed, load, the speed of the vehicle can be taken into account to exclude particular life situations in technical control for example.
[0030] Dans une étape 102, le catalyseur 3 est vidé de son oxygène grâce au déclenchement d'une combustion riche, ce qui permet de commencer la mesure dans une étape 103. Le catalyseur 3 est alors rempli en oxygène grâce au déclenchement d'une combustion pauvre et le calcul de la capacité brute de stockage en oxygène OSC_Bru du catalyseur 3 est réalisé dans une étape 104. Au cours de cette même étape 104, les capacités de stockage en oxygène corrigées OSC_Corr_N, OSC_Corr_V, OSC_Corr_OBD sont calculées respectivement pour des facteurs correctifs dépendant de la température du catalyseur 3 et du débit des gaz d'échappement correspondants à différents états types du catalyseur 3, à savoir un premier facteur correctif correspondant à un catalyseur 3 considéré comme neuf OSC_Corr_N, un second facteur correctif correspondant à un catalyseur 3 considéré comme vieilli OSC_Corr_V, et un troisième facteur correctif correspondant à un catalyseur 3 considéré comme défaillant OSC_Corr_OBD. On adapte donc le facteur correctif selon que l'on considère que le catalyseur 3 est classé en catégorie neuf ou vieilli ou défaillant. In a step 102, the catalyst 3 is emptied of its oxygen by triggering a rich combustion, which allows to start the measurement in a step 103. The catalyst 3 is then filled with oxygen through the triggering of a lean combustion and the calculation of the OSC_Bru oxygen storage capacity of the catalyst 3 is carried out in a step 104. During this same step 104, the oxygen storage capacities corrected OSC_Corr_N, OSC_Corr_V, OSC_Corr_OBD are calculated respectively for corrective factors dependent on the temperature of the catalyst 3 and the flow rate of the corresponding exhaust gases to different typical states of the catalyst 3, namely a first corrective factor corresponding to a catalyst 3 considered as new OSC_Corr_N, a second correction factor corresponding to a catalyst 3 considered aged OSC_Corr_V, and a third corrective factor corresponding to a catalyst 3 considered as failed OSC_Corr_OBD. The corrective factor is therefore adjusted according to whether it is considered that the catalyst 3 is classified in category nine or aged or defective.
[0031 ] Une fois que la sonde 7 en aval du catalyseur 3 détecte de l'oxygène dans une étape 105, c'est-à-dire que le catalyseur 3 a atteint sa capacité de stockage, la mesure OSC_Bru est arrêtée dans une étape 106. [0032] En fonction du niveau de capacité brute de stockage en oxygène OSC_Bru atteint sur le point de fonctionnement moteur (déterminé par le débit Deb des gaz à l'échappement et la température du catalyseur 3), le procédé choisi donc la capacité de stockage en oxygène corrigée OSC_Corr_N, OSC_Corr_V, OSC_Corr_OBD à prendre en compte dans le calcul du vieillissement du catalyseur 3. [0033] Pour cela, plusieurs règles de décisions sont mises en œuvre. Suivant ces règles, la capacité brute de stockage en oxygène mesurée OSC_Bru est comparée, dans une étape 107, avec des seuils de décision S_Dec_N, S_Dec_V correspondants à différents états du catalyseur 3. On définit ainsi un premier seuil de décision S_Dec_N correspondant à un catalyseur 3 neuf et un deuxième seuil de décision S_Dec_V correspondant à un catalyseur 3 vieilli. Once the probe 7 downstream of the catalyst 3 detects oxygen in a step 105, that is to say that the catalyst 3 has reached its storage capacity, the OSC_Bru measurement is stopped in a step 106. [0032] Depending on the level of OSC_Bru oxygen storage capacity reached at the engine operating point (determined by the flow rate Deb of the exhaust gases and the catalyst temperature 3), the process therefore chooses the capacity corrected oxygen storage OSC_Corr_N, OSC_Corr_V, OSC_Corr_OBD to be taken into account in the calculation of catalyst aging 3. [0033] For this, several decision rules are implemented. According to these rules, the measured raw oxygen storage capacity OSC_Bru is compared, in a step 107, with decision thresholds S_Dec_N, S_Dec_V corresponding to different states of the catalyst 3. A first decision threshold S_Dec_N corresponding to a catalyst is thus defined. 3 nine and a second decision threshold S_Dec_V corresponding to an aged catalyst 3.
[0034] Les seuils de décision S_Dec_N, S_Dec_V sont obtenus à partir d'une cartographie Cart_Dec qui est fonction du débit Deb des gaz d'échappement et de la température du catalyseur 3. Ces seuils de décision S_Dec_N, S_Dec_V, comme pour la capacité de stockage, peuvent être calculés pendant l'étape 104 ce qui permet d'avoir une évolution de ceux-ci pendant la mesure en cas de changement de point de fonctionnement, ou être choisis à la fin de la mesure ce qui contraint de réaliser une mesure de la capacité brute de stockage en oxygène OSC_Bru sur un seul point de fonctionnement. The decision thresholds S_Dec_N, S_Dec_V are obtained from a map Cart_Dec which is a function of the flow rate Deb of the exhaust gas and the temperature of the catalyst 3. These decision thresholds S_Dec_N, S_Dec_V, as for the storage capacity, can be calculated during step 104, which makes it possible to have an evolution of these during the measurement in the event of a change of operating point, or be chosen at the end of the measurement, which makes it necessary to measure the raw OSC_Bru oxygen storage capacity at a single operating point.
[0035] Dans le cas où la capacité brute de stockage en oxygène OSC_Bru est supérieure au premier seuil de décision S_Dec_N correspondant à un catalyseur 3 neuf alors la capacité brute de stockage en oxygène OSC_Bru est corrigée avec un facteur correctif correspondant l'état catalyseur 3 neuf (cf. OSC_Corr_N). [0036] Dans le cas où la capacité brute de stockage en oxygène OSC_Bru est inférieure au premier seuil de décision S_Dec_N et supérieure au deuxième seuil de décision S_Dec_V correspondant à un catalyseur 3 vieilli alors la capacité brute de stockage en oxygène OSC_Bru est corrigée avec un facteur correctif correspondant à l'état catalyseur 3 vieilli (cf. OSC_Corr_V). [0037] Dans le cas où la capacité brute de stockage en oxygène OSC_Bru est inférieure au deuxième seuil de décision S_Dec_V alors la capacité brute de stockage en oxygène OSC_Bru est corrigée avec un facteur correctif correspondant à l'état catalyseur 3 défaillant (cf. OSC_Corr_OBD). In the case where the raw oxygen storage capacity OSC_Bru is greater than the first decision threshold S_Dec_N corresponding to a new catalyst 3 then the raw oxygen storage capacity OSC_Bru is corrected with a corrective factor corresponding to the catalyst state 3 new (see OSC_Corr_N). In the case where the raw oxygen storage capacity OSC_Bru is less than the first decision threshold S_Dec_N and greater than the second decision threshold S_Dec_V corresponding to a catalyst 3 aged then the raw oxygen storage capacity OSC_Bru is corrected with a corrective factor corresponding to the aged catalyst state 3 (see OSC_Corr_V). In the case where the raw oxygen storage capacity OSC_Bru is lower than the second decision threshold S_Dec_V then the raw oxygen storage capacity OSC_Bru is corrected with a correction factor corresponding to the failed catalyst state 3 (see OSC_Corr_OBD). ).
[0038] Une capacité de stockage en oxygène corrigée OSC_Corr est alors déterminée avec le facteur correctif sélectionné en fonction de la comparaison précédente dans une étape 108 qui pourra se produire au même moment que l'étape 104. La figure 6 met en évidence que le procédé selon l'invention permet d'obtenir une capacité de stockage en oxygène corrigée constante quel que soit l'état du catalyseur 3 (cf. courbe OSC_Corr_N pour un catalyseur neuf; OSC_Corr_V pour un catalyseur vieilli; OSC_Corr_OBD pour un catalyseur défaillant). A corrected oxygen storage capacity OSC_Corr is then determined with the corrective factor selected as a function of the preceding comparison in a step 108 which may occur at the same time as step 104. FIG. 6 shows that the process according to the invention makes it possible to obtain a constant corrected oxygen storage capacity whatever the state of the catalyst 3 (see curve OSC_Corr_N for a new catalyst, OSC_Corr_V for an aged catalyst, OSC_Corr_OBD for a defective catalyst).
[0039] Le calculateur moteur peut ensuite déterminer le vieillissement du catalyseur 3, dans une étape 109, en fonction de la capacité de stockage en oxygène corrigée ainsi déterminée. Le vieillissement d'un catalyseur 3 est exprimé en kilomètres. Ce kilométrage n'est pas celui du véhicule car le profil de conduite, entre autre, dégrade plus ou moins vite le catalyseur 3. Le calcul consiste à caractériser la capacité brute de stockage en oxygène OSC_Bru d'un catalyseur 3 neuf, d'un catalyseur 3 vieilli suivant une gamme précise représentant le profil moyen d'un conducteur ayant parcouru 100 000 kilomètres, et d'un catalyseur 3 défaillant suivant une gamme jusqu'à ce que les émissions polluantes du véhicule dépassent les seuils de défaillance établis par une réglementation donnée. Une table de correspondance entre capacité brute de stockage en oxygène OSC_Bru et kilométrage du catalyseur 3 est intégrée dans le calculateur moteur pour convertir la capacité brute de stockage en oxygène OSC_Bru en kilomètre. The engine computer can then determine the aging of the catalyst 3, in a step 109, depending on the corrected oxygen storage capacity thus determined. The aging of a catalyst 3 is expressed in kilometers. This mileage is not that of the vehicle because the driving profile, among other things, degrades more or less rapidly catalyst 3. The calculation consists in characterizing the raw oxygen storage capacity OSC_Bru of a new catalyst 3, a catalyst 3 aged according to a precise range representing the average profile of a driver having traveled 100,000 kilometers, and a Catalyst 3 defaults in a range until the pollutant emissions of the vehicle exceed the failure thresholds established by a given regulation. A table of correspondence between raw oxygen storage capacity OSC_Bru and mileage of the catalyst 3 is integrated in the engine calculator to convert the raw oxygen storage capacity OSC_Bru in kilometer.
[0040] Alternativement, il sera possible de déterminer uniquement la capacité de stockage en oxygène corrigée correspondant à l'état du catalyseur 3 déterminé après comparaison de la capacité brute de stockage en oxygène OSC_Bru avec les seuils de décision S_Dec_N, S_Dec_V. Autrement dit, dans ce cas, on ne calcul pas les capacités de stockages corrigées avec les trois facteurs correctifs, mais uniquement celle corrigée avec le facteur correctif correspondant à l'état du catalyseur 3. On réalise ainsi des économies de ressources de calcul au détriment de la précision de calcul. Alternatively, it will be possible to determine only the corrected oxygen storage capacity corresponding to the state of the catalyst 3 determined after comparing the raw oxygen storage capacity OSC_Bru with the decision thresholds S_Dec_N, S_Dec_V. In other words, in this case, we do not calculate the corrected storage capacities with the three correction factors, but only that corrected with the corrective factor corresponding to the state of the catalyst 3. There is thus savings of computing resources to the detriment calculation precision.

Claims

REVENDICATIONS
1. Procédé de détermination du vieillissement d'un catalyseur (3) équipant une ligne d'échappement (1 ), notamment de véhicule automobile, ladite ligne d'échappement (1 ) étant équipée de sondes à oxygène (6, 7) en amont et en aval du catalyseur (3), ce procédé comportant: 1. Method for determining the aging of a catalyst (3) fitted to an exhaust line (1), in particular of a motor vehicle, said exhaust line (1) being equipped with oxygen sensors (6, 7) upstream and downstream of the catalyst (3), this process comprising:
- une étape de mesure (103) d'une capacité brute de stockage en oxygène (OSC_Bru) du catalyseur (3) à un instant donné,  a measurement step (103) of a raw oxygen storage capacity (OSC_Bru) of the catalyst (3) at a given instant,
- une étape de détermination d'un état du catalyseur (3) en fonction de la mesure de la capacité brute de stockage en oxygène (OSC_Bru),  a step of determining a state of the catalyst (3) as a function of the measurement of the raw oxygen storage capacity (OSC_Bru),
- une étape de détermination (108) d'une capacité de stockage en oxygène corrigée à partir d'un facteur correctif qui dépend d'une température du catalyseur (3), d'un débit des gaz d'échappement, et de l'état du catalyseur (3), et a step of determining (104) a corrected oxygen storage capacity from a corrective factor which depends on a catalyst temperature (3), a flow rate of the exhaust gases, and on the state of the catalyst (3), and
- une étape de détermination (109) du vieillissement du catalyseur (3) en fonction de la capacité de stockage en oxygène corrigée.  a step of determining (109) the aging of the catalyst (3) as a function of the corrected oxygen storage capacity.
2. Procédé selon la revendication 1 , caractérisé en ce qu'il comporte une étape de comparaison (107) de la capacité brute de stockage en oxygène (OSC_Bru) mesurée avec des seuils de décision (S_Dec_N, S_Dec_V) correspondants à différents états du catalyseur (3), le facteur correctif étant sélectionné en fonction de la comparaison précédente. 2. Method according to claim 1, characterized in that it comprises a step of comparing (107) raw oxygen storage capacity (OSC_Bru) measured with decision thresholds (S_Dec_N, S_Dec_V) corresponding to different states of the catalyst (3), the corrective factor being selected according to the previous comparison.
3. Procédé selon la revendication 2, caractérisé en ce qu'on définit un premier seuil de décision (S_Dec_N) correspondant à un état de catalyseur (3) neuf et un deuxième seuil de décision (S_Dec_V) correspondant à un état de catalyseur (3) vieilli. 3. Method according to claim 2, characterized in that defines a first decision threshold (S_Dec_N) corresponding to a new state of catalyst (3) and a second decision threshold (S_Dec_V) corresponding to a state of catalyst (3). ) aged.
4. Procédé selon la revendication 3, caractérisé en ce que, dans le cas où la capacité brute de stockage en oxygène (OSC_Bru) est supérieure au premier seuil de décision (S_Dec_N) correspondant à l'état catalyseur (3) neuf alors la capacité brute de stockage en oxygène (OSC_Bru) est corrigée avec un premier facteur correctif correspondant à un catalyseur (3) neuf. 4. Method according to claim 3, characterized in that, in the case where the raw oxygen storage capacity (OSC_Bru) is greater than the first decision threshold (S_Dec_N) corresponding to the catalyst state (3) nine then the capacity raw oxygen storage (OSC_Bru) is corrected with a first corrective factor corresponding to a new catalyst (3).
5. Procédé selon la revendication 3 ou 4, caractérisé en ce que, dans le cas où la capacité brute de stockage en oxygène (OSC_Bru) est inférieure au premier seuil de décision (S_Dec_N) correspondant à l'état de catalyseur (3) neuf et supérieure au deuxième seuil de décision (S_Dec_V) correspondant à l'état de catalyseur (3) vieilli alors la capacité brute de stockage en oxygène (OSC_Bru) est corrigée avec un deuxième facteur correctif correspondant à un catalyseur (3) vieilli. 5. Method according to claim 3 or 4, characterized in that, in the case where the raw oxygen storage capacity (OSC_Bru) is lower than the first decision threshold (S_Dec_N) corresponding to the state of catalyst (3) nine and greater than the second decision threshold (S_Dec_V) corresponding to the aged catalyst state (3) then the raw oxygen storage capacity (OSC_Bru) is corrected with a second corrective factor corresponding to an aged catalyst (3).
6. Procédé selon l'une quelconque des revendications 3 à 5, caractérisé en ce que, dans le cas où la capacité brute de stockage en oxygène (OSC_Bru) est inférieure au deuxième seuil de décision (S_Dec_V) correspondant à l'état catalyseur (3) vieilli alors la capacité brute de stockage en oxygène (OSC_Bru) est corrigée avec un troisième facteur correctif correspondant à un état catalyseur (3) défaillant. 6. Method according to any one of claims 3 to 5, characterized in that, in the case where the raw oxygen storage capacity (OSC_Bru) is less than the second decision threshold (S_Dec_V) corresponding to the catalyst state ( 3) then aged the raw oxygen storage capacity (OSC_Bru) is corrected with a third corrective factor corresponding to a failed catalyst state (3).
7. Procédé selon l'une quelconque des revendications 2 à 6, caractérisé en ce que les seuils de décision (S_Dec_N, S_Dec_V) sont obtenus à partir d'une cartographie (Cart_Dec) qui est fonction du débit des gaz d'échappement et de la température du catalyseur (3). 7. Method according to any one of claims 2 to 6, characterized in that the decision thresholds (S_Dec_N, S_Dec_V) are obtained from a map (Cart_Dec) which is a function of the exhaust gas flow rate and the temperature of the catalyst (3).
8. Procédé selon l'une quelconque des revendications 2 à 7, caractérisé en ce qu'il comporte: 8. Method according to any one of claims 2 to 7, characterized in that it comprises:
- une étape de calcul préalable de différentes capacités de stockage en oxygène corrigées (OSC_Corr_N, OSC_Corr_V, OSC_Corr_OBD) avec un ensemble de facteurs correctifs correspondant à différents états du catalyseur (3), et  a step of prior calculation of various corrected oxygen storage capacities (OSC_Corr_N, OSC_Corr_V, OSC_Corr_OBD) with a set of correction factors corresponding to different states of the catalyst (3), and
- une étape de sélection de la capacité de stockage en oxygène corrigée (OSC_Corr_N, OSC_Corr_V, OSC_Corr_OBD) en fonction de la comparaison entre la capacité brute de stockage en oxygène mesurée (OSC_Bru) et les seuils de décision (S_Dec_N, S_Dec_V) correspondants à différents états du catalyseur (3).  a step of selecting the corrected oxygen storage capacity (OSC_Corr_N, OSC_Corr_V, OSC_Corr_OBD) as a function of the comparison between the measured raw oxygen storage capacity (OSC_Bru) and the decision thresholds (S_Dec_N, S_Dec_V) corresponding to different catalyst states (3).
9. Procédé selon l'une quelconque des revendications 2 à 8, caractérisé en ce que la mesure de la capacité brute de stockage en oxygène (OSC_Bru) ainsi que la capacité de stockage en oxygène corrigée et les seuils de décision (S_Dec_N, S_Dec_V) sont obtenus suivant les étapes suivantes: 9. Method according to any one of claims 2 to 8, characterized in that the measurement of the raw oxygen storage capacity (OSC_Bru) and the corrected oxygen storage capacity and the decision thresholds (S_Dec_N, S_Dec_V) are obtained by the following steps:
- une étape de vidage du catalyseur (3) en oxygène par déclenchement d'une combustion riche,  a step of emptying the catalyst (3) with oxygen by triggering a rich combustion,
- une étape de commencement de la mesure (103),  a step of beginning of the measurement (103),
- une étape de remplissage du catalyseur (3) en oxygène par déclenchement d'une combustion pauvre, et  a step of filling the catalyst (3) with oxygen by triggering a poor combustion, and
- une étape d'arrêt de la mesure (106) lorsque la sonde à oxygène (7) en aval du catalyseur (3) détecte de l'oxygène.  - A step of stopping the measurement (106) when the oxygen sensor (7) downstream of the catalyst (3) detects oxygen.
PCT/FR2018/050610 2017-04-21 2018-03-14 Method for determining the ageing of a catalytic converter of a motor vehicle exhaust line WO2018193174A1 (en)

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