US20160169073A1 - System and method for diagnosing the selective catalytic reduction system of a motor vehicle - Google Patents

System and method for diagnosing the selective catalytic reduction system of a motor vehicle Download PDF

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US20160169073A1
US20160169073A1 US14/896,727 US201414896727A US2016169073A1 US 20160169073 A1 US20160169073 A1 US 20160169073A1 US 201414896727 A US201414896727 A US 201414896727A US 2016169073 A1 US2016169073 A1 US 2016169073A1
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catalytic reduction
selective catalytic
reduction system
ammonia
stored
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Romain CHANZY
Damiano Di-Penta
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Renault SAS
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Renault SAS
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    • 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
    • F01N3/18—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 characterised by methods of operation; Control
    • F01N3/20—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 characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/206—Adding periodically or continuously substances to exhaust gases for promoting purification, e.g. catalytic material in liquid form, NOx reducing agents
    • 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
    • F01N11/002—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring or estimating temperature or pressure in, or 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
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • 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
    • F01N3/18—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 characterised by methods of operation; Control
    • F01N3/20—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 characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • 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
    • F01N3/18—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 characterised by methods of operation; Control
    • F01N3/20—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 characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
    • 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
    • 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
    • F01N2560/026—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor for measuring or detecting NOx
    • 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
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/18—Ammonia
    • 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
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
    • 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
    • F01N2900/1616—NH3-slip from catalyst
    • 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
    • Y02T10/12—Improving ICE efficiencies
    • 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 area of the invention is the on-board diagnosis of functions of a motor vehicle, more particularly the diagnosis of the catalytic reduction of polluting emissions of a diesel-type motor vehicle.
  • the selective catalytic reduction system is known as an effective means for treatment for nitrous oxides (NO X ).
  • the system comprises continuous treatment of nitrous oxide emissions (nitrates and nitrites). It requires the use of a catalyst and a reducing agent injector arranged in the exhaust system.
  • the system therefore requires the addition of an additional tank containing the reducing agent (AdBlue for example), the specific injection system, a system for mixing the reducing agent with the exhaust gases, and a catalyst system accelerating the reduction of nitrous oxides by the reducing agent injected and/or stored on the catalyst.
  • the reducing agent AdBlue for example
  • the specific injection system a system for mixing the reducing agent with the exhaust gases
  • a catalyst system accelerating the reduction of nitrous oxides by the reducing agent injected and/or stored on the catalyst.
  • the quantity of reducing agent injected and the quantity of reducing agent stored on the catalyst must be finely adapted: in fact, an overdose of reducing agent (stored or injected) would only pointlessly increase the consumption of reducing agent and perhaps generate emissions of ammonia at the exhaust (a highly odorous and highly toxic compound). Under-dosing however limits the efficiency obtained and hence increases the emissions of nitrous oxides at the exhaust.
  • the selective catalytic reduction system stores the ammonia (NH 3 ) contained in the reducing agent, such as urea.
  • the ammonia thus stored in the selective catalytic reduction system then reduces the nitrous oxides (NO x ).
  • NO x nitrous oxides
  • NH 3 ammonia storage capacity
  • NH 3 ammonia storage capacity
  • ammonia storage capacity a value characterized by a maximum mass of ammonia (NH 3 ) which can be stored, which is a direct reflection of the ageing state of the SCR.
  • Patent WO 2008/103113 discloses an on-board diagnosis (OBD) of the SCR system based on the efficiency of the treatment of nitrous oxides NO x under specific conditions.
  • OBD on-board diagnosis
  • the efficiency of treatment of the nitrous oxides NO x by the selective catalytic reduction system SCR greatly depends on the NO 2 /NO x ratio between the nitrogen dioxide and the nitrous oxides at the inlet to the selective catalytic reduction system SCR. This ratio cannot be measured and is affected by the sulphurization level of the catalyst DOC, and by the soot level of the particulate filter FAP upstream of the selective catalytic reduction system SCR.
  • the efficiency determined by the model of the on-board selective catalytic reduction system SCR is compared with that determined via a sensor for nitrous oxides NO x arranged downstream of the selective catalytic reduction system SCR, under conditions where the NO 2 /NO x ratio is a priori nominal, i.e. after desulphurization of the catalyst DOC and/or regeneration of the particulate filter FAP. If, under nominal conditions, the efficiency measured is less than the efficiency calculated by the model, a failure of the selective catalytic reduction system SCR is detected.
  • Document WO 2007/037730 discloses a diagnosis system for the selective catalytic reduction system SCR based on comparison of the efficiency of the treatment of the nitrous oxides NO x by a nitrous oxides NO x sensor arranged downstream of the selective catalytic reduction system SCR, with a nominal efficiency at a given engine operating point (load, speed). If the efficiency of the SCR is lower than the reference, a failure is detected.
  • An object of the invention is a system for diagnosing the selective catalytic reduction system of a motor vehicle equipped with an internal combustion engine connected via an exhaust manifold successively to an assembly comprising a nitrous oxide catalyst and a particulate filter, and a selective catalytic reduction system.
  • the system comprises:
  • the means for determining the maximum mass of ammonia stored in the selective catalytic reduction system may comprise a means for determining the ammonia level at the outlet from the selective catalytic reduction system as a function of the signal received from the measuring means, and a means for modeling the selective catalytic reduction system, and able to estimate the levels of ammonia and nitrous oxides downstream of the selective catalytic reduction system via a model.
  • the means for determining the maximum mass may also comprise a calculation means able to determine the difference between the level of ammonia measured at the outlet from the selective catalytic reduction system and the modeled values for the levels of ammonia and nitrous oxides downstream of the selective catalytic reduction system, and to determine a new value for the maximum mass of ammonia stored in the selective catalytic reduction system if the difference is positive, and to transmit the new value for the maximum mass of ammonia stored in the selective catalytic reduction system to the means for modeling the selective catalytic reduction system in order to determine new values until the difference is zero.
  • the calculation means may be able to transmit the maximum mass of ammonia stored in the selective catalytic reduction system when the difference is zero.
  • the fault signal for the selective catalytic reduction system may assume a first value if the value determined for the maximum mass of ammonia stored in the selective catalytic reduction system is less than a threshold, while it assumes a second value if this is not the case.
  • the means for modeling the selective catalytic reduction system may be able to estimate the ammonia level downstream of the selective catalytic reduction via a model, as a function of the ratio between the nitrogen dioxide and the nitrous oxides downstream of the exhaust manifold, the temperature upstream of the selective catalytic reduction system, the mass of urea injected upstream of the selective catalytic reduction system, the maximum mass of ammonia stored in the selective catalytic reduction system, the exhaust gas flow, the level of ammonia upstream of the selective catalytic reduction system, and the level of nitrous oxides upstream of the selective catalytic reduction system.
  • the means for modeling the selective catalytic reduction system may also be able to determine the ratio between nitrogen dioxide and nitrogen monoxide downstream of the exhaust manifold, as a function of the temperature upstream of the assembly of the particulate filter and the catalyst, the exhaust gas flow from the internal combustion engine, and the level of nitrous oxides downstream of the exhaust manifold.
  • Another object of the invention is a method for diagnosing the selective catalytic reduction system of a motor vehicle equipped with an internal combustion engine connected via an exhaust manifold successively to an assembly comprising a nitrous oxide catalyst and a particulate filter, and a selective catalytic reduction system.
  • the method comprises the following steps:
  • the maximum mass of ammonia stored in the selective catalytic reduction system may be determined by performing the following steps:
  • a fault signal assuming a first value may be emitted for the selective catalytic reduction system, while it assumes a second value if this is not the case.
  • the levels of ammonia and nitrous oxides downstream of the selective catalytic reduction system may be estimated via a model, as a function of the ratio between the quantity of nitrogen monoxide and nitrogen dioxide downstream of the exhaust manifold, the temperature upstream of the selective catalytic reduction system, the mass of urea injected upstream of the selective catalytic reduction system, the maximum mass of ammonia stored in the selective catalytic reduction system, the exhaust gas flow, the level of ammonia upstream of the selective catalytic reduction system, and the level of nitrous oxides upstream of the selective catalytic reduction system.
  • the ratio between the nitrogen monoxide and the nitrogen dioxide downstream of the exhaust manifold may be determined as a function of the temperature upstream of the assembly of the particulate filter and the catalyst, the exhaust gas flow from the internal combustion engine, and the level of nitrous oxides downstream of the exhaust manifold.
  • FIG. 1 shows the principal elements of an internal combustion engine equipped with a selective catalytic reduction system and an on-board diagnostic system
  • FIG. 2 illustrates the main elements of a system for determining the maximum ammonia storage capacity
  • FIG. 3 illustrates the main steps of the method for diagnosing the selective catalytic reduction system.
  • FIG. 1 illustrates an internal combustion engine 1 of a motor vehicle connected by its exhaust manifold to an exhaust pipe.
  • a first temperature sensor 2 mounted on the exhaust pipe downstream of the exhaust manifold, we see successively a first temperature sensor 2 , an assembly 3 comprising an oxidation catalyst and a particulate filter, a urea injector 4 , a second temperature sensor 5 , a selective catalytic reduction system 6 and a nitrous oxide sensor 7 .
  • the oxidation catalyst is housed in the assembly 3 upstream of the particulate filter, i.e. closer to the engine 1 , so as to reach its ignition temperature more quickly.
  • the second temperature sensor 5 is installed upstream of the injector 4 , such that the temperature measurement is not disrupted by the urea injection.
  • the internal combustion engine 1 is connected directly or via a control means to an on-board diagnostic system 8 via a connection providing the exhaust gas flow and the flow of nitrous oxides NO x . These flows result from a map or from an estimation means, depending in particular on the operating point of the internal combustion engine 1 .
  • the first temperature sensor 2 is connected to the on-board diagnostic system 8 via a connection 2 a providing the temperature upstream of the assembly 3 .
  • the second temperature sensor 5 is connected to the on-board diagnostic system 8 via a connection 5 a providing the temperature upstream of the selective catalytic reduction system 6 .
  • the nitrous oxides sensor 7 is connected to the on-board diagnostic system 8 via a connection 7 a providing the quantity of nitrous oxides and ammonia downstream of the selective catalytic reduction system 6 .
  • the maximum mass of ammonia stored is estimated under conditions of leakage of this ammonia.
  • the nitrous oxides (NO x ) sensor, reference 7 arranged downstream of the selective catalytic reduction system 6 , cannot distinguish nitrous oxides (NO x ) from ammonia (NH 3 ). This property can then be exploited to detect leaks of ammonia (NH 3 ), deduce from this the maximum mass of ammonia stored, and diagnose a failure as a function of this value.
  • the model described below is included in the system 9 for determining the maximum ammonia storage capacity. To be able to estimate the maximum mass of ammonia stored, the model is linked to the nitrous oxides NO x sensor, reference 7 .
  • the selective catalytic reduction system is evacuated via a control means 8 a for the evacuation and injection of urea, linked to an actuator via connection 6 a .
  • the control means 8 a may interrupt the urea injection by the injector 4 in order to obtain an effect equivalent to evacuation by consumption of all the ammonia present in the selective catalytic reduction system. Since evacuation allows an absolute reference value to be set, the mass determined does not comprise any relativity and can therefore be compared with a threshold by a comparison means 8 b in order to determine a failure of the selective catalytic reduction system.
  • the description presented below firstly comprises presentation of the modeling of the selective catalytic reduction system 6 , then the method and system of diagnosing the selective catalytic reduction system.
  • FIG. 2 illustrates a system 9 for determining the maximum ammonia storage capacity. This has a means 9 a for determining the ammonia level at the outlet from the selective catalytic reduction system 6 , as a function of the measurement by the nitrous oxides sensor 7 .
  • the modeling of the selective catalytic reduction system begins by estimating the ammonia mass. This is given by a reduced model based on the physico-chemical phenomena taking place in the exhaust tract.
  • this ratio ⁇ between the nitrogen dioxide (NO 2 ) and the nitrous oxides (NO x ) cannot be measured. It must therefore be estimated via a model or map as a function of the exhaust gas flow q ech and the temperature at the inlet to the oxidation catalyst (DOC), called T doc .
  • the exhaust flow q ech is measured or modeled as a function of the different engine gas flows.
  • X no2 in ⁇ ( T doc ,q ech ) ⁇ X nox in
  • the level of nitrous oxides (NO x ) at the outlet from the engine X in nox can be measured via a sensor or estimated via a model.
  • * is a site which can receive a molecule of ammonia NH 3 NH 3 *: represents a stored molecule of ammonia NH 3 O 2 : a molecule of dioxygen N 2 : a molecule of dinitrogen NO: a molecule of nitrogen monoxide NO 2 : a molecule of nitrogen dioxide.
  • the equation system illustrates such a model.
  • the level X in nh3 of ammonia (NH 3 ) upstream of the selective catalytic reduction system can be estimated as a function of the injected urea quantity.
  • the means 9 b for modeling the selective catalytic reduction system determines the variation in mass dm nh3 /dt of ammonia (NH 3 ) as a function of time, the level X out nox of nitrous oxides (NO x ) and the level X out nh3 of ammonia (NH 3 ) downstream of the selective catalytic reduction system, as a function of the level X in nox of nitrous oxides (NO x ) upstream of the selective catalytic reduction system and the flow q ech of exhaust gas from the internal combustion engine 1 , the temperature T scr of these gases at the inlet to the selective catalytic reduction system from the second temperature sensor 5 , the ratio ⁇ between the nitrogen dioxide (NO 2 ) and the nitrous oxides (NO x ), the maximum mass m max nh3 of ammonia stored in the selective catalytic reduction system, the level X in nh3 of ammonia (NH 3 ) up
  • the level X out nox of nitrous oxides (NO x ) and the level X out nh3 of ammonia (NH 3 ) downstream of the selective catalytic reduction system it is possible to determine the maximum mass of ammonia stored via an observer.
  • the measurement from the nitrous oxides sensor (NO x ) downstream of the selective catalytic reduction system is broken down to take account of its capacity to measure both nitrous oxides and ammonia. The following equation takes into account this breakdown.
  • X out,capt nox value of the measurement of the nitrous oxides sensor
  • X out nox level of nitrous oxides
  • X out nh3 level of ammonia (NH 3 ) downstream of the selective catalytic reduction system.
  • the system 9 for determining the maximum ammonia storage capacity also comprises a subtractor 9 c connected at the inlet to the means 9 a for determining the ammonia level at the outlet from the selective catalytic reduction system 6 , and to the means 9 b for modeling the selective catalytic reduction system, and connected at the outlet to a calculation means 9 d able to determine the maximum mass m max nh3 of ammonia stored in the selective catalytic reduction system as a function of the signal received from the subtractor 9 c and from a memory 9 e.
  • the subtractor 9 c allows determination of the parameter ⁇ by application of equation 6, by subtracting the values received from the means 9 b for modeling the selective catalytic reduction system from the value received from the determination means 9 a.
  • the calculation means 9 d determines the maximum mass m max nh3 of ammonia stored in the selective catalytic reduction system as a function of the signal received from the memory 9 e when the system 9 for determining the maximum ammonia storage capacity is initialized. In other situations, the calculation means 9 d determines the maximum mass m max nh3 of ammonia stored in the selective catalytic reduction system by integrating, relative to time, the product of parameter ⁇ by the saved constant K. In doing this, the calculation means 9 d applies the third equation of the equation system (Eq 5).
  • the calculation means 9 d also estimates whether the parameter ⁇ is zero. If so, the calculation means 9 d emits the determined value for the maximum mass m max nh3 of ammonia stored in the selective catalytic reduction system.
  • the comparison means 8 b receives from the calculation means 9 d a signal carrying the maximum mass m max nh3 of ammonia stored in the selective catalytic reduction system 6 .
  • the comparison means 8 b performs the comparison of the maximum mass with a memorized threshold, allowing a distinction between a selective catalytic reduction system in good condition and a faulty selective catalytic reduction system. If the maximum mass is greater than the threshold, a signal for absence of failure is transmitted, otherwise a failure signal is transmitted. Alternatively, only the failure signal is emitted, and only when the emission conditions are combined.
  • the model is initialized with a maximum m max nh3 of ammonia stored in the catalyst equal to the value of the maximum mass of ammonia which can be stored in a selective catalytic reduction system in good condition, or 4 g in the present example, then the values for the level of nitrous oxides and ammonia (NH 3 ) downstream of the selective catalytic reduction system are determined.
  • parameter ⁇ we determine the value of parameter ⁇ as a function of the modeled values for the levels of nitrous oxides and ammonia (NH 3 ) downstream of the selective catalytic reduction system, and of the measurement from the nitrous oxides sensor.
  • the current value of the maximum mass m max nh3 of ammonia stored in the catalyst is saved and compared with a threshold. If the value is greater than the threshold, the selective catalytic reduction system is in good condition, otherwise a fault is detected and a warning signal emitted.
  • the method for diagnosing the selective catalytic reduction system illustrated by FIG. 3 uses the models and equations explained above.
  • the method comprises a first step 10 during which the ammonia mass is evacuated.
  • a first step 10 during which the ammonia mass is evacuated.
  • an evacuation is performed so that the estimate of the maximum mass m max nh3 of ammonia stored in the selective catalytic reduction system can begin from an absolute reference substantially equal to zero. This evacuation takes place by cutting the urea injection for a few minutes.
  • a specific mass of urea is injected which is sufficiently high for the selective catalytic reduction system to either reach or exceed the limit for leakage of ammonia (NH 3 ). In other words, more ammonia (NH 3 ) is injected than the system can theoretically contain.
  • the mass to be injected may be determined as a function of the maximum mass of ammonia stored in a catalytic reduction system having no fault.
  • a third step 12 we estimate the ammonia level x out nh3 and the nitrous oxides level x out nh3 downstream of the selective catalytic reduction system via the model by applying equation 5.
  • the third step is repeated until the value of parameter ⁇ is zero.
  • the last value of the maximum mass m max nh3 of ammonia stored in the selective catalytic reduction system is then saved.
  • a fourth step 13 we compare the maximum mass m max nh3 of ammonia stored in the selective catalytic reduction with a threshold. If the maximum mass is greater than the threshold, the selective catalytic reduction system has no fault. If this is not the case, the selective catalytic reduction system has a fault.
  • a signal corresponding to the state of the selective catalytic reduction system is then transmitted at the outlet.

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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)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
US14/896,727 2013-06-28 2014-06-13 System and method for diagnosing the selective catalytic reduction system of a motor vehicle Abandoned US20160169073A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR1356261A FR3007795B1 (fr) 2013-06-28 2013-06-28 Systeme et procede de diagnostic de la reduction catalytique selective d'un vehicule automobile.
FR1356261 2013-06-28
PCT/FR2014/051452 WO2014207340A1 (fr) 2013-06-28 2014-06-13 Système et procédé de diagnostic de la réduction catalytique sélective d'un véhicule automobile

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EP3523519B1 (de) * 2016-10-10 2020-11-11 Vitesco Technologies GmbH Katalysator-alterungserkennung ohne zusätzliche systemkomponente
EP3546712A4 (en) * 2016-11-24 2019-11-20 Toyota Jidosha Kabushiki Kaisha SYSTEM FOR DIAGNOSIS OF ANOMALIES OF AN EXHAUST GAS CLEANING DEVICE
US10570799B2 (en) * 2018-05-09 2020-02-25 Ngk Spark Plug Co., Ltd. Purification control device
US11313268B2 (en) * 2019-05-09 2022-04-26 Robert Bosch Gmbh Method of monitoring an SCR catalyst
DE102019206873A1 (de) * 2019-05-13 2020-11-19 Robert Bosch Gmbh Überwachung des Zustands eines Katalysators zur Stickoxidminderung durch Vergleich des Stickoxid-Sensorsignals mit einem modellierten Wert
US20220154615A1 (en) * 2019-08-07 2022-05-19 Cummins Inc. Systems and methods for measuring exhaust gas species and scr catalyst nox storage for scr-related controls and diagnostics
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CN113701959A (zh) * 2020-05-21 2021-11-26 北京福田康明斯发动机有限公司 车辆排气管路漏气检测方法
CN114352393A (zh) * 2020-10-13 2022-04-15 通用汽车环球科技运作有限责任公司 选择性催化还原（scr）故障检测系统和方法
CN114810289A (zh) * 2021-06-10 2022-07-29 长城汽车股份有限公司 一种对scr系统状态的检测方法、装置、电子设备及车辆
US20240052796A1 (en) * 2022-08-11 2024-02-15 Cummins Inc. Systems and methods for forecasting aftertreatment temperatures over a horizon

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CN105308282B (zh) 2018-02-09
EP3014082A1 (fr) 2016-05-04
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KR102059602B1 (ko) 2019-12-26
CN105308282A (zh) 2016-02-03
KR20160026868A (ko) 2016-03-09
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EP3014082B1 (fr) 2017-05-03
FR3007795B1 (fr) 2015-06-19

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