WO2015158375A1 - Method for monitoring the filtering capability of a particle filter - Google Patents

Method for monitoring the filtering capability of a particle filter Download PDF

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Publication number
WO2015158375A1
WO2015158375A1 PCT/EP2014/057721 EP2014057721W WO2015158375A1 WO 2015158375 A1 WO2015158375 A1 WO 2015158375A1 EP 2014057721 W EP2014057721 W EP 2014057721W WO 2015158375 A1 WO2015158375 A1 WO 2015158375A1
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WO
WIPO (PCT)
Prior art keywords
filter
exhaust gas
particle
value
particulate
Prior art date
Application number
PCT/EP2014/057721
Other languages
German (de)
French (fr)
Inventor
Tino Arlt
Michael Nienhoff
Paul Rodatz
Thomas Schön
Original Assignee
Continental Automotive Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Continental Automotive Gmbh filed Critical Continental Automotive Gmbh
Priority to PCT/EP2014/057721 priority Critical patent/WO2015158375A1/en
Publication of WO2015158375A1 publication Critical patent/WO2015158375A1/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
    • 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
    • F01N2430/00—Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics
    • 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
    • F01N2550/04—Filtering activity of particulate 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
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/05—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being a particulate 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
    • F01N2900/1402—Exhaust gas composition
    • 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 present invention relates to a method for monitoring the filterability of a particulate filter arranged in the exhaust system of a motor vehicle.
  • the combustion of fuel in an internal combustion engine causes unwanted particles. Since these particles are harmful to health ⁇ , the legislation has set emission limits. To be able to comply with these particle limits, especially in the exhaust system of modern
  • Particle sensor installed in the exhaust system to measure the exhaust gas concentration.
  • the particulate filter is intact, only a small particle concentration in the exhaust gas is measured by the particulate sensor. However, if the filter is damaged, the particulate sensor measures an abnormally high particulate concentration in the exhaust gas. In this procedure, there is now the problem of being able to distinguish between an intact and a defective filter safely under all operating conditions of the system.
  • Such particle filters are, in particular, soot filters which are installed in the exhaust gas line of diesel engines become.
  • the associated particle sensors are accordingly soot sensors.
  • the determination of the filter efficiency is carried out here only at certain operating points in order to reduce the scattering.
  • a defective particulate filter is characterized in that the particulate emissions (of a system in which this component is installed) exceed a limit in the exhaust gas test.
  • An intact particulate filter is just below this limit.
  • the tolerances of the sensor and the model are high.
  • the emissions are optimized for operating points that are approached in the exhaust gas test, ie at a low level. As a result, have the Particle sensor and the model a higher inaccuracy in these operating points. According to the current state of the art, therefore, there must be a considerable distance between an intact and a defective particle filter, so that they can be reliably distinguished from one another during the monitoring carried out.
  • the present invention has for its object to provide a method of the type described above, with which the filterability of a particulate filter can be monitored very accurately. With this method, in particular the accuracy of the determination of the state of
  • Particle filter can be increased, without causing the emissions he ⁇ significantly increase.
  • Performing a first diagnostic phase by determining an efficiency value of the particulate filter and comparing it to an expected value; upon reaching or falling below the expected value by the efficiency value setting a suspected error; when suspecting a fault, increasing the particulate emissions in the exhaust gas of the associated motor vehicle engine and thereby reducing the dispersion of the determined filter efficiency value;
  • Performing a second diagnostic phase analogous to the first diagnostic phase it is possible to achieve the abovementioned object, in particular to increase the accuracy of the determination of the state of the particle filter, without causing the emissions to increase significantly.
  • a two-stage method is proposed according to the invention. In the first phase of the efficiency value of the particulate filter is determined and compared with a He ⁇ maintenance value analogous to the known methods. This comparison can be made at operating points with a low particulate emission level. If the determined filter efficiency value is the
  • the engine particle emissions are now increased by appropriate measures.
  • the increased engine emissions also increase the emissions downstream of the particulate filter, which reduces the signal tolerances.
  • the smaller tolerances mean that the dispersion of the determined filter efficiency value can be reduced. In this area a reliable distinction between an intact and a defective particle filter is possible.
  • a threshold value is preferably determined with regard to the particle concentration in the exhaust gas, beyond which a reliable differentiation of different filter efficiency values is possible.
  • This threshold value preferably corresponds to a particle ⁇ concentration value from which the tolerance bands of the filtration efficiency values for an intact and a defective
  • the particulate emissions in the exhaust gas are specially increased so that the Particle concentration in the exhaust gas is above the determined threshold.
  • the first diagnostic phase is preferably carried out at operating points with a low particulate emission level. It is therefore possible to keep the Parti ⁇ kelemissionen at a low level. It is only when a fault is suspected, the Partike ⁇ lemissionen be increased in the exhaust gas. Such an increase therefore only takes place in exceptional cases, if a reasonable suspicion exists.
  • the increase of the particulate emissions in the exhaust gas is carried out in the inventive method, for example by adjusting the Abgasmolrate, change the injection duration and / or the injection phase.
  • the inventive method is preferably used for monitoring the filterability of a soot filter, especially in diesel engines of motor vehicles.
  • the particle concentration in the exhaust gas is preferably determined by means of a particle sensor connected downstream of the particle filter.
  • Figure 1 is a diagram showing the filter efficiency for
  • Figure 2 is a flow diagram of a method for monitoring the filter capability of a soot filter.
  • Figure 1 shows the tolerance band of the filter efficiency for an intact soot filter with nominal 80% filter efficiency and a defective soot filter with only 40%. The values are plotted against the engine soot concentration. It can be seen that for low concentrations (area 1, to the left of the solid vertical line) the tolerance band opens strongly and the worst efficiency (eff_pf_min_0, 8) of the intact filter and the best efficiency (eff_pf_max_04) of the defective filter overlap. Therefore, in area 1 a robust distinction between the two filters is not possible. But this is the area that is typically approached in the exhaust test.
  • the method for monitoring the filterability of the soot filter arranged in the exhaust gas line of a diesel vehicle runs as follows: According to FIG. 2, in step 1, an efficiency value of the soot filter is determined in a first diagnostic phase. In step 2, this efficiency value is compared to an expected value. If the expectation value achieved by the efficiency value or under ⁇ reached, in step 3, a suspected error is set. Only when setting a suspected error in step 4 the
  • Soot emissions in the exhaust gas of the associated diesel engine increased. This reduces the dispersion of the determined filter efficiency value, as shown in FIG. Thereafter, a second diagnostic phase is then carried out analogously to the first diagnostic phase.
  • a second diagnostic phase is then carried out analogously to the first diagnostic phase.
  • an efficiency value of the soot filter is again determined, and in step 6, this efficiency value is compared with an expected value.
  • the tolerance bands for a defective filter and an intact filter now have a clear distance from one another (in the region of the increased carbon black concentration), so that a clear distinction from the filters is possible.

Abstract

A method is described for monitoring the filtering capability of a particle filter arranged in the exhaust system of a motor vehicle. In a first diagnostic phase, an efficiency value of the filter is determined and compared with an expected value. Upon reaching or underrunning the expected value by the efficiency value, a suspected error is set. Upon setting a suspected error, the particle emissions in the exhaust gas are increased. A second diagnostic phase is then executed analogous to the first diagnostic phase. It can thereby be clearly distinguished whether the filter is defective or intact.

Description

Beschreibung description
Verfahren zur Überwachung der Filterfähigkeit eines Method for monitoring the filterability of a
Partikelfilters particulate filter
Die vorliegende Erfindung betrifft ein Verfahren zur Überwachung der Filterfähigkeit eines im Abgasstrang eines Kraftfahrzeuges angeordneten Partikelfilters. Bei der Verbrennung von Kraftstoff in einem Verbrennungsmotor entstehen ungewollt Partikel. Da diese Partikel gesundheits¬ schädlich sind, hat der Gesetzgeber Emissionsgrenzwerte festgelegt. Um diese Partikelgrenzwerte einhalten zu können, werden insbesondere in den Abgasstrang von modernen The present invention relates to a method for monitoring the filterability of a particulate filter arranged in the exhaust system of a motor vehicle. The combustion of fuel in an internal combustion engine causes unwanted particles. Since these particles are harmful to health ¬, the legislature has set emission limits. To be able to comply with these particle limits, especially in the exhaust system of modern
PKW-Diesel-Motoren Partikelfilter eingebaut. Diese werden typischerweise als Wandstromfilter auf Basis von Keramikwerkstoffen ausgeführt. Der Gesetzgeber verlangt zudem, dass die Funktionstüchtigkeit des Filters während seines Betriebes („On Board Diagnose") überwacht wird. Um diese Anforderung zu er- füllen, wird ein dem Partikelfilter nachgeschalteter Car diesel engines particle filter installed. These are typically designed as wall-flow filters based on ceramic materials. Legislation also requires that the functionality of the filter be monitored during its operation (on-board diagnostics) .To meet this requirement, a filter downstream of the particulate filter is required
Partikelsensor in den Abgasstrang eingebaut, um die Abgaskonzentration zu messen.  Particle sensor installed in the exhaust system to measure the exhaust gas concentration.
Falls das Partikelfilter intakt ist, wird vom Partikelsensor nur eine geringe Partikelkonzentration im Abgas gemessen. Wenn das Filter jedoch geschädigt ist, misst der Partikelsensor eine abnorm hohe Partikelkonzentration im Abgas. Bei dieser Vorgehensweise besteht nunmehr die Problematik, unter allen Betriebsbedingungen des Systems sicher zwischen einem intakten und einem defekten Filter unterscheiden zu können. If the particulate filter is intact, only a small particle concentration in the exhaust gas is measured by the particulate sensor. However, if the filter is damaged, the particulate sensor measures an abnormally high particulate concentration in the exhaust gas. In this procedure, there is now the problem of being able to distinguish between an intact and a defective filter safely under all operating conditions of the system.
Bei derartigen Partikelfiltern handelt es sich insbesondere um Rußfilter, die in den Abgasstrang von Dieselmotoren eingebaut werden. Die zugehörigen Partikelsensoren sind dementsprechend Rußsensoren . Such particle filters are, in particular, soot filters which are installed in the exhaust gas line of diesel engines become. The associated particle sensors are accordingly soot sensors.
Um eine entsprechende Überwachung der Filterfähigkeit des Partikelfilters bzw. eine Zustandsbestimmung des To a corresponding monitoring of the filterability of the particulate filter or a state determination of the
Partikelfilters durchzuführen, ist es bekannt, mithilfe einer modellierten Motor-Partikel-Emission und der mithilfe eines Partikelsensors gemessenen Partikelkonzentration nach dem Partikelfilter die Filtereffizienz des Filters zu bestimmen. Der entsprechende ermittelte Filtereffizienzwert wird mit einem Erwartungswert verglichen. Der Erwartungswert prognostiziert die Filtereffizienz für einen defekten anzeigepflichtigen Partikelfilter. Bei einem Partikelfilter, der gerade die zulässigen Emissionen überschreitet, soll der Erwartungswert also exakt der anhand des Messsignals ermittelten Effizienz ent¬ sprechen. Wenn nunmehr die ermittelte Effizienz gleich dem Erwartungswert ist oder unter diesem liegt, ist der It is known to use a modeled engine particle emission and the particle concentration measured after the particulate filter particle filter to determine the filter efficiency of the filter. The corresponding determined filter efficiency value is compared with an expected value. The expected value predicts the filter efficiency for a defective reportable particulate filter. In a particulate filter, which just exceeds the permitted emissions, the expected value will therefore speak exactly the efficiency determined from the measured signal ent ¬. Now, if the determined efficiency is equal to or below the expected value, the
Partikelfilter geschädigt und kann als defekt erkannt werden. Die Bestimmung der Filtereffizienz wird hierbei nur in bestimmten Betriebspunkten durchgeführt, um die Streuungen zu reduzieren. Particle filter damaged and can be recognized as defective. The determination of the filter efficiency is carried out here only at certain operating points in order to reduce the scattering.
Ein defekter Partikelfilter ist dadurch gekennzeichnet, dass die Partikelemissionen (eines Systems, in dem dieses Bauteil verbaut ist) im Abgastest einen Grenzwert überschreiten. Ein intakter Partikelfilter hingegen liegt knapp unterhalb dieses Grenzwertes. In der Praxis gibt es einen Graubereich zwischen den beiden Komponenten, da sowohl das Signal des Partikelsensors als auch das Rohemissions-Modell (modellierte MotorPartikel- Emission) Toleranzen unterliegt, so dass daher die Bestimmung der Filtereffizienz toleranzbehaftet ist. Speziell bei niedrigen Partikelemissionen sind die Toleranzen des Sensors und des Modells hoch. In typischen Applikationen sind für Betriebspunkte, welche im Abgastest angefahren werden, die Emissionen optimiert, d.h. auf einem niedrigen Niveau. Dadurch haben der Partikelsensor und das Modell eine höhere Ungenauigkeit in diesen Betriebspunkten. Nach heutigem Stand der Technik muss daher ein erheblicher Abstand zwischen einem intakten und einem defekten Partikelfilter liegen, damit diese bei der durchgeführten Überwachung zuverlässig voneinander unterschieden werden können . A defective particulate filter is characterized in that the particulate emissions (of a system in which this component is installed) exceed a limit in the exhaust gas test. An intact particulate filter, however, is just below this limit. In practice, there is a gray area between the two components, since both the signal of the particle sensor and the raw emission model (modeled engine particle emission) are subject to tolerances, so that the determination of the filter efficiency is tolerant. Especially with low particulate emissions, the tolerances of the sensor and the model are high. In typical applications, the emissions are optimized for operating points that are approached in the exhaust gas test, ie at a low level. As a result, have the Particle sensor and the model a higher inaccuracy in these operating points. According to the current state of the art, therefore, there must be a considerable distance between an intact and a defective particle filter, so that they can be reliably distinguished from one another during the monitoring carried out.
Der vorliegenden Erfindung liegt die Aufgabe zugrunde, ein Verfahren der eingangs beschriebenen Art zur Verfügung zu stellen, mit dem sich die Filterfähigkeit eines Partikelfilters besonders exakt überwachen lässt. Mit diesem Verfahren soll insbesondere die Genauigkeit der Zustandsbestimmung des The present invention has for its object to provide a method of the type described above, with which the filterability of a particulate filter can be monitored very accurately. With this method, in particular the accuracy of the determination of the state of
Partikelfilters erhöht werden, ohne dabei die Emissionen er¬ heblich ansteigen zu lassen. Particle filter can be increased, without causing the emissions he ¬ significantly increase.
Diese Aufgabe wird erfindungsgemäß bei einem Verfahren der angegebenen Art durch die folgenden Schritte gelöst: This object is achieved in a method of the type indicated by the following steps:
Durchführen einer ersten Diagnosephase durch Ermitteln eines Effizienzwertes des Partikelfilters und Vergleichen desselben mit einem Erwartungswert; bei Erreichen oder Unterschreiten des Erwartungswertes durch den Effizienzwert Setzen eines Fehlerverdachtes; bei Setzen eines Fehlerverdachtes Erhöhen der Partikelemissionen im Abgas des zugehörigen Kraftfahrzeugmotors und hierdurch Verringerung der Streuung des ermittelten Filtereffizienzwertes; und Performing a first diagnostic phase by determining an efficiency value of the particulate filter and comparing it to an expected value; upon reaching or falling below the expected value by the efficiency value setting a suspected error; when suspecting a fault, increasing the particulate emissions in the exhaust gas of the associated motor vehicle engine and thereby reducing the dispersion of the determined filter efficiency value; and
Durchführen einer zweiten Diagnosephase analog zur ersten Diagnosephase . Mit dem erfindungsgemäßen Verfahren gelingt es, die vorstehend genannte Aufgabe zu lösen, insbesondere die Genauigkeit der Zustandsbestimmung des Partikelfilters zu erhöhen, ohne die Emissionen erheblich ansteigen zu lassen. Dazu wird erfin- dungsgemäß ein zweistufiges Verfahren vorgeschlagen. In der ersten Phase wird analog zu dem bekannten Verfahren der Effizienzwert des Partikelfilters ermittelt und mit einem Er¬ wartungswert verglichen. Dieser Vergleich kann an Betriebspunkten mit einem niedrigen Partikelemissionsniveau durchge- führt werden. Falls der ermittelte Filtereffizienzwert denPerforming a second diagnostic phase analogous to the first diagnostic phase. With the method according to the invention, it is possible to achieve the abovementioned object, in particular to increase the accuracy of the determination of the state of the particle filter, without causing the emissions to increase significantly. For this purpose, a two-stage method is proposed according to the invention. In the first phase of the efficiency value of the particulate filter is determined and compared with a He ¬ maintenance value analogous to the known methods. This comparison can be made at operating points with a low particulate emission level. If the determined filter efficiency value is the
Erwartungswert erreicht oder unterschreitet, wird nicht direkt ein Fehler eingetragen, sondern erst ein Fehlerverdacht gesetzt. Expected value is reached or not reached, an error is not entered directly, but only a suspected error is set.
In der zweiten Phase werden nun durch geeignete Maßnahmen die Motorpartikelemissionen erhöht. Durch die erhöhten Motoremissionen steigen auch die Emissionen nach dem Partikelfilter, wodurch die Toleranzen des Signals kleiner werden. Die geringeren Toleranzen bewirken, dass die Streuung des ermittelten Filtereffizienzwertes reduziert werden kann. In diesem Bereich ist eine zuverlässige Unterscheidung zwischen einem intakten und einem defekten Partikelfilter möglich. In the second phase, the engine particle emissions are now increased by appropriate measures. The increased engine emissions also increase the emissions downstream of the particulate filter, which reduces the signal tolerances. The smaller tolerances mean that the dispersion of the determined filter efficiency value can be reduced. In this area a reliable distinction between an intact and a defective particle filter is possible.
Vorzugsweise wird bei dem erfindungsgemäßen Verfahren in Bezug auf die Partikelkonzentration im Abgas ein Schwellenwert er- mittelt, jenseits von dem eine zuverlässige Unterscheidung von unterschiedlichen Filtereffizienzwerten möglich ist. Dieser Schwellenwert entspricht dabei vorzugsweise einem Partikel¬ konzentrationswert, ab dem sich die Toleranzbänder der Filtereffizienzwerte für einen intakten und einen defekten In the method according to the invention, a threshold value is preferably determined with regard to the particle concentration in the exhaust gas, beyond which a reliable differentiation of different filter efficiency values is possible. This threshold value preferably corresponds to a particle ¬ concentration value from which the tolerance bands of the filtration efficiency values for an intact and a defective
Partikelfilter nicht mehr überlappen. Do not overlap the particle filter anymore.
Bei dem erfindungsgemäßen Verfahren werden daher die Partikelemissionen im Abgas speziell so erhöht, dass die Partikelkonzentration im Abgas über dem ermittelten Schwellenwert liegt. In the method according to the invention, therefore, the particulate emissions in the exhaust gas are specially increased so that the Particle concentration in the exhaust gas is above the determined threshold.
Es hat sich gezeigt, dass sich mit dem erfindungsgemäßen Verfahren besonders gute Ergebnisse erzielen lassen, wenn die Partikelemissionen im Abgas so erhöht werden, dass sich eine Partikelkonzentration von mehr als 10 mg/m3 im Abgas ergibt. In diesem Bereich ist eine zuverlässige Unterscheidung zwischen defekten und intakten Filtern möglich. Dies ist generell abhängig vom Emissions- und Filterwirkungsgrad und von dem Modell und den Sensortoleranzen. It has been found that particularly good results can be achieved with the method according to the invention if the particle emissions in the exhaust gas are increased so that a particle concentration of more than 10 mg / m 3 in the exhaust gas results. In this area a reliable distinction between defective and intact filters is possible. This is generally dependent on the emission and filter efficiency and on the model and sensor tolerances.
Bei dem erfindungsgemäßen Verfahren wird die erste Diagnosephase vorzugsweise an Betriebspunkten mit einem niedrigen Partike- lemissionsniveau durchgeführt. Es gelingt daher, die Parti¬ kelemissionen auf einem niedrigen Niveau zu halten. Erst dann, wenn der Verdacht eines Fehlers besteht, werden die Partike¬ lemissionen im Abgas erhöht. Eine solche Erhöhung findet daher nur in Ausnahmefällen statt, wenn ein begründeter Fehlerverdacht besteht. In the method according to the invention, the first diagnostic phase is preferably carried out at operating points with a low particulate emission level. It is therefore possible to keep the Parti ¬ kelemissionen at a low level. It is only when a fault is suspected, the Partike ¬ lemissionen be increased in the exhaust gas. Such an increase therefore only takes place in exceptional cases, if a reasonable suspicion exists.
Das Erhöhen der Partikelemissionen im Abgas wird bei dem erfindungsgemäßen Verfahren beispielsweise durch Verstellung der Abgasführrate, Änderung der Einspritzdauer und/oder des Ein- spritzphasings durchgeführt. The increase of the particulate emissions in the exhaust gas is carried out in the inventive method, for example by adjusting the Abgasführrate, change the injection duration and / or the injection phase.
Das erfindungsgemäße Verfahren wird vorzugsweise zur Überwachung der Filterfähigkeit eines Rußfilters, speziell bei Dieselmotoren von Kraftfahrzeugen, eingesetzt. Die Partikelkonzentration im Abgas wird dabei vorzugsweise mithilfe eines dem Partikelfilter nachgeschalteten Partikelsensors ermittelt. The inventive method is preferably used for monitoring the filterability of a soot filter, especially in diesel engines of motor vehicles. The particle concentration in the exhaust gas is preferably determined by means of a particle sensor connected downstream of the particle filter.
Bei dem erfindungsgemäßen Verfahren, das als zweistufiges Verfahren ausgebildet ist, kann in jedem Fall die Emissions- erhöhung auf den Fehlerverdachtsfall reduziert werden. Die Emissionen in einem System, in dem der Partikelfilter intakt ist, werden nicht beeinflusst. Die Erfindung wird nachfolgend anhand eines Ausführungs¬ beispieles in Verbindung mit der Zeichnung im Einzelnen erläutert. Es zeigen: In the method according to the invention, which is designed as a two-stage process, in each case the emission be reduced to the error suspected case. The emissions in a system where the particulate filter is intact are not affected. The invention will be explained below with reference to an embodiment ¬ example in conjunction with the drawings in detail. Show it:
Figur 1 ein Diagramm, das die Filtereffizienz für Figure 1 is a diagram showing the filter efficiency for
einen intakten Partikelfilter und einen defekten an intact particulate filter and a defective one
Partikelfilter zeigt; und Particle filter shows; and
Figur 2 ein Ablaufdiagramm eines Verfahrens zur Über wachung der Filterfähigkeit eines Rußfilters. Figure 2 is a flow diagram of a method for monitoring the filter capability of a soot filter.
Figur 1 zeigt das Toleranzband der Filtereffizienz für eine intakten Rußfilter mit nominal 80 % Filtereffizienz und einen defekten Rußfilter mit nur 40 %. Die Werte sind aufgetragen über die Motor-Rußkonzentration. Man erkennt, dass für niedrige Konzentrationen (Bereich 1, links von der durchgezogenen vertikalen Linie) sich das Toleranzband stark öffnet und sich der schlechteste Wirkungsgrad (eff_pf_min_0 , 8 ) des intakten Filters und der beste Wirkungsgrad (eff_pf_max_04 ) des defekten Filters überlappen. Daher ist im Bereich 1 eine robuste Unterscheidung der beiden Filter nicht möglich. Dies ist aber der Bereich, welcher im Abgastest typischerweise angefahren wird. Figure 1 shows the tolerance band of the filter efficiency for an intact soot filter with nominal 80% filter efficiency and a defective soot filter with only 40%. The values are plotted against the engine soot concentration. It can be seen that for low concentrations (area 1, to the left of the solid vertical line) the tolerance band opens strongly and the worst efficiency (eff_pf_min_0, 8) of the intact filter and the best efficiency (eff_pf_max_04) of the defective filter overlap. Therefore, in area 1 a robust distinction between the two filters is not possible. But this is the area that is typically approached in the exhaust test.
Falls nun in diesem Bereich 1 eine Filtereffizienz unterhalb des besten Wirkungsgrades (eff_pf_max_0 , 4 ) des defekten Filters gemessen wird, wird ein Fehlerverdacht gesetzt. Anschließend werden die Rohemissionen erhöht, und die Diagnose wird im Bereich 2 (rechts von der durchgezogenen vertikalen Linie) wiederholt. In diesem Bereich ist eine zuverlässige Unterscheidung beider Filter möglich. Im Einzelnen läuft dabei das Verfahren zur Überwachung der Filterfähigkeit des im Abgasstrang eines Dieselfahrzeuges angeordneten Rußfilters wie folgt ab: Gemäß Figur 2 wird in Schritt 1 in einer ersten Diagnosephase ein Effizienzwert des Rußfilters ermittelt. In Schritt 2 wird dieser Effizienzwert mit einem Erwartungswert verglichen. Wenn der Erwartungswert durch den Effizienzwert erreicht oder unter¬ schritten wird, wird in Schritt 3 ein Fehlerverdacht gesetzt. Nur bei Setzen eines Fehlerverdachtes werden in Schritt 4 dieIf a filter efficiency below the best efficiency (eff_pf_max_0, 4) of the defective filter is measured in this area 1, a suspected error is set. Subsequently, the raw emissions are increased and the diagnosis is repeated in region 2 (to the right of the solid vertical line). In this area, a reliable distinction between the two filters is possible. In detail, the method for monitoring the filterability of the soot filter arranged in the exhaust gas line of a diesel vehicle runs as follows: According to FIG. 2, in step 1, an efficiency value of the soot filter is determined in a first diagnostic phase. In step 2, this efficiency value is compared to an expected value. If the expectation value achieved by the efficiency value or under ¬ reached, in step 3, a suspected error is set. Only when setting a suspected error in step 4 the
Rußemissionen im Abgas des zugehörigen Dieselmotors erhöht. Hierdurch wird die Streuung des ermittelten Filtereffizienzwertes verringert, wie in Figur 1 gezeigt. Danach wird dann analog zur ersten Diagnosephase eine zweite Diagnosephase durchgeführt. In Schritt 5 wird wiederum ein Effizienzwert des Rußfilters ermittelt, und in Schritt 6 wird dieser Effizienzwert mit einem Erwartungswert verglichen. Gemäß Figur 1 besitzen jetzt (im Bereich der erhöhten Rußkonzentration) die Toleranzbänder für einen defekten und einen intakten Filter einen deutlichen Abstand voneinander, so dass eine deutliche Unterscheidung von den Filtern möglich ist. Soot emissions in the exhaust gas of the associated diesel engine increased. This reduces the dispersion of the determined filter efficiency value, as shown in FIG. Thereafter, a second diagnostic phase is then carried out analogously to the first diagnostic phase. In step 5, an efficiency value of the soot filter is again determined, and in step 6, this efficiency value is compared with an expected value. According to FIG. 1, the tolerance bands for a defective filter and an intact filter now have a clear distance from one another (in the region of the increased carbon black concentration), so that a clear distinction from the filters is possible.

Claims

Patentansprüche claims
1. Verfahren zur Überwachung der Filterfähigkeit eines im Abgasstrang eines Kraftfahrzeuges angeordneten Partikelfilters mit den folgenden Schritten: 1. A method for monitoring the filterability of a arranged in the exhaust line of a motor vehicle particulate filter with the following steps:
Durchführen einer ersten Diagnosephase durch Ermitteln eines Effizienzwertes des Partikelfilters und Vergleichen desselben mit einem Erwartungswert; bei Erreichen oder Unterschreiten des Erwartungswertes durch den Effizienzwert Setzen eines Fehlerverdachtes; bei Setzen eines Fehlerverdachtes Erhöhen der Partikelemissionen im Abgas des zugehörigen Kraftfahrzeugmotors und hierdurch Verringerung der Streuung des ermittelten Filtereffizienzwertes; und Performing a first diagnostic phase by determining an efficiency value of the particulate filter and comparing it to an expected value; upon reaching or falling below the expected value by the efficiency value setting a suspected error; when suspecting a fault, increasing the particulate emissions in the exhaust gas of the associated motor vehicle engine and thereby reducing the dispersion of the determined filter efficiency value; and
Durchführen einer zweiten Diagnosephase analog zur ersten Diagnosephase. Performing a second diagnostic phase analogous to the first diagnostic phase.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass in Bezug auf die Partikelkonzentration im Abgas ein Schwellenwert ermittelt wird, jenseits von dem eine zuverlässige Unter- Scheidung von unterschiedlichen Filtereffizienzwerten möglich ist . 2. The method according to claim 1, characterized in that a threshold value is determined with respect to the particle concentration in the exhaust gas, beyond which a reliable distinction between different different filter efficiency values is possible.
3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, dass der Schwellenwert einem Partikelkonzentrationswert entspricht, ab dem sich die Toleranzbänder der Filtereffizienzwerte für einen intakten und einen defekten Partikelfilter nicht mehr überlappen . 3. The method according to claim 2, characterized in that the threshold corresponds to a particle concentration value, from which the tolerance bands of the filter efficiency values for an intact and a defective particulate filter no longer overlap.
4. Verfahren nach Anspruch 2 oder 3, dadurch gekennzeichnet, dass die Partikelemissionen im Abgas so erhöht werden, dass die Partikelkonzentration im Abgas über dem ermittelten Schwellenwert liegt. 4. The method according to claim 2 or 3, characterized in that the particle emissions in the exhaust gas are increased so that the particle concentration in the exhaust gas is above the determined threshold value.
5. Verfahren nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass die Partikelemissionen im Abgas so erhöht werden, dass sich eine Partikelkonzentration von mehr als 10 mg/m3 im Abgas ergibt. 5. The method according to any one of the preceding claims, characterized in that the particulate emissions in the exhaust gas are increased so that a particle concentration of more than 10 mg / m 3 results in the exhaust gas.
6. Verfahren nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass die erste Diagnosephase an Be¬ triebspunkten mit einem niedrigen Partikelemissionsniveau durchgeführt wird. 6. The method according to any one of the preceding claims, characterized in that the first diagnostic phase is carried out at loading ¬ operating points with a low particle emission level.
7. Verfahren nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass das Erhöhen der Partikelemissionen im Abgas durch Verstellung der Abgasrückführrate, Änderung der Einspritzdauer und/oder des Einspritzphasings durchgeführt wird. 7. The method according to any one of the preceding claims, characterized in that the increasing of the particulate emissions in the exhaust gas is performed by adjusting the exhaust gas recirculation rate, change the injection duration and / or the injection phase.
8. Verfahren nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass es zur Überwachung der Filterfä¬ higkeit eines Rußfilters eingesetzt wird. 8. The method according to any one of the preceding claims, characterized in that it is used to monitor the Filterfä ¬ ability of a soot filter.
9. Verfahren nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass die Partikelkonzentration im Abgas mithilfe eines dem Partikelfilter nachgeschalteten 9. The method according to any one of the preceding claims, characterized in that the particle concentration in the exhaust gas downstream of the particle filter
Partikelsensors ermittelt wird. Particle sensor is determined.
PCT/EP2014/057721 2014-04-16 2014-04-16 Method for monitoring the filtering capability of a particle filter WO2015158375A1 (en)

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CN116718534A (en) * 2023-08-09 2023-09-08 深圳丰汇汽车电子有限公司 Particulate filter filtration efficiency detecting system based on data analysis

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WO2009115542A1 (en) * 2008-03-20 2009-09-24 Continental Automotive Gmbh Diagnostic method and diagnostic system for a particle filter of an internal combustion engine, in particular for a soot filter in a diesel motor vehicle
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JP2005325812A (en) * 2004-05-17 2005-11-24 Honda Motor Co Ltd Failure determining device for filter
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FR3045102A1 (en) * 2015-12-11 2017-06-16 Renault Sas METHOD FOR CONTROLLING A MOTORIZATION DEVICE AND ASSOCIATED MOTORIZATION DEVICE
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