DE102012202668A1 - Method for detecting error at metering valve of selective catalytic reduction catalyst system used in e.g. diesel engine, involves detecting blockage of metering valve when pressure difference is below threshold value - Google Patents
Method for detecting error at metering valve of selective catalytic reduction catalyst system used in e.g. diesel engine, involves detecting blockage of metering valve when pressure difference is below threshold value Download PDFInfo
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- DE102012202668A1 DE102012202668A1 DE201210202668 DE102012202668A DE102012202668A1 DE 102012202668 A1 DE102012202668 A1 DE 102012202668A1 DE 201210202668 DE201210202668 DE 201210202668 DE 102012202668 A DE102012202668 A DE 102012202668A DE 102012202668 A1 DE102012202668 A1 DE 102012202668A1
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- Prior art keywords
- metering valve
- pressure
- catalyst system
- pressure difference
- threshold value
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Classifications
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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
- F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
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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
- F01N3/2066—Selective catalytic reduction [SCR]
- F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
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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
- F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
- F01N2550/14—Systems for adding secondary air into exhaust
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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
- F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
- F01N2900/04—Methods of control or diagnosing
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- 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
Abstract
Description
Die Erfindung betrifft ein Verfahren zur Fehlererkennung an einem Dosierventil eines SCR-Katalysatorsystems. Weiterhin betrifft die vorliegende Erfindung ein Computerprogramm, das alle Schritte des erfindungsgemäßen Verfahrens ausführt und in einem Rechengerät abläuft. Schließlich betrifft die vorliegende Erfindung ein Computerprogrammprodukt mit Programmcode, der auf einem maschinenlesbaren Träger gespeichert ist, zur Durchführung des erfindungsgemäßen Verfahrens, wenn das Programm auf einem Rechengerät ausgeführt wird.The invention relates to a method for error detection on a metering valve of an SCR catalyst system. Furthermore, the present invention relates to a computer program that executes all the steps of the method according to the invention and runs in a computing device. Finally, the present invention relates to a computer program product with program code, which is stored on a machine-readable carrier, for carrying out the method according to the invention when the program is executed on a computing device.
Stand der TechnikState of the art
Um die immer strengeren Abgasgesetzgebungen zu erfüllen, ist es notwendig, Stickstoffdioxide im Abgas von Verbrennungskraftmaschinen, insbesondere von Dieselmotoren, zu verringern. Hierzu ist es bekannt, im Abgasbereich von Brennkraftmaschinen einen SCR-Katalysator (Selective Catalytic Reduction) anzuordnen, der dem Abgas der Verbrennungskraftmaschine enthaltene Stickoxide (NOx) in Gegenwart eines Reduktionsmittels zu Stickstoff reduziert. Hierdurch kann der Anteil von Stickoxid im Abgas erheblich verringert werden. Für den Ablauf der Reaktion wird Ammoniak (NH3) benötigt, das dem Abgas zugemischt wird. Als Reduktionsmittel werden daher NH3 bzw. NH3-abspaltende Reagenzien eingesetzt. In der Regel wird hierfür eine wässrige Harnstofflösung (Harnstoffwasserlösung) verwendet, die vor dem SCR-Katalysator im Abgasstrang eingespritzt wird. Aus dieser Lösung bildet sich Ammoniak, das als Reduktionsmittel wirkt. Eine 32,5 %ige wässrige Harnstofflösung ist unter dem Markennamen AdBlue® kommerziell erhältlich. In order to meet the increasingly stringent exhaust gas legislation, it is necessary to reduce nitrogen oxides in the exhaust gas of internal combustion engines, especially diesel engines. For this purpose, it is known to arrange an SCR catalytic converter (selective catalytic reduction) in the exhaust region of internal combustion engines, which reduces the nitrogen oxides (NOx) contained in the exhaust gas of the internal combustion engine in the presence of a reducing agent to nitrogen. As a result, the proportion of nitrogen oxide in the exhaust gas can be significantly reduced. For the course of the reaction ammonia (NH 3 ) is required, which is admixed to the exhaust gas. As reducing agents therefore NH 3 or NH 3 -splitting reagents are used. As a rule, an aqueous urea solution (urea-water solution) is used for this, which is injected in the exhaust gas line upstream of the SCR catalytic converter. From this solution forms ammonia, which acts as a reducing agent. A 32.5% aqueous urea solution is commercially available under the trade name AdBlue ®.
In einem SCR-Katalysatorsystem wird mit einem elektromagnetisch betätigten Nadelventil die Harnstoffwasserlösung ins Abgas eindosiert. Dieses Dosierventil wird dazu von einem Steuergerät entsprechend bestromt. Öffnet sich das Ventil, so zeigt dessen Stromverlauf einen charakteristischen Knick, der durch die Gegeninduktion der bewegten Ventilnadel entsteht. Dieser Stromknick wird vom Steuergerät abgetastet und durch eine Berechnung in einen numerischen Wert umgesetzt. Dieser Wert kann zur Fehlererkennung an dem Dosierventil genutzt werden. Dabei gilt, dass das Ventil bei einem hohen Wert geschaltet hat und ein niedriger Wert darauf hinweist, dass das Ventil nicht geschaltet hat und somit blockiert ist. Die Ausprägung des Stromknicks wird allerdings von etlichen Faktoren beeinflusst. Einer davon ist der Grad der magnetischen Sättigung im Öffnungszeitpunkt. Dieser wiederum hängt davon ab, bei welchem Stromniveau, d. h. bei welcher Magnetkraft, sich die Nadel in Bewegung setzt. Die Nadel wird durch eine Feder und durch die hydraulische Druckkraft der Harnstoffwasserlösung in ihrem Sitz gehalten. Diese Kraft muss von dem Elektromagneten überwunden werden. Bei derzeitigen Anwendungen dieser Fehlerdiagnose kann es beispielsweise bei einer sehr kalten Spule zu Schaltvorgängen kommen, die im Stromverlauf nicht oder für eine Auswertung nicht ausreichend abgebildet werden. Der daraus berechnete Wert ist dann niedrig, obwohl das Dosierventil geschaltet hat. Dadurch steigt das Risiko, dass fälschlicherweise ein blockiertes Ventil diagnostiziert wird. Solche Fehldiagnosen sind besonders bei kalten Spulen in Kombination mit einer hohen Batteriespannung, sowie hohen Federund/oder Druckkräften wahrscheinlich. In an SCR catalyst system, the urea water solution is metered into the exhaust gas with an electromagnetically actuated needle valve. This metering valve is energized accordingly by a control unit. If the valve opens, its current flow shows a characteristic kink, which results from the mutual induction of the moving valve needle. This current kink is sampled by the control unit and converted into a numerical value by a calculation. This value can be used to detect faults on the dosing valve. In this case, the valve has switched to a high value and a low value indicates that the valve has not switched and is thus blocked. However, the severity of the current kink is influenced by a number of factors. One of these is the degree of magnetic saturation at the time of opening. This in turn depends on the current level, ie. H. at which magnetic force, the needle sets in motion. The needle is held in place by a spring and by the hydraulic pressure force of the urea water solution. This force must be overcome by the electromagnet. In current applications of this fault diagnosis, for example, in the case of a very cold coil, switching operations may occur which are not sufficiently reflected in the course of the current or are not sufficiently displayed for an evaluation. The calculated value is then low, although the metering valve has switched. This increases the risk of incorrectly diagnosing a blocked valve. Such misdiagnoses are likely, especially with cold coils in combination with a high battery voltage, as well as high spring and / or pressure forces.
Offenbarung der ErfindungDisclosure of the invention
Das erfindungsgemäße Verfahren zur Fehlererkennung an einem Dosierventil eines SCR-Katalysatorsystems umfasst das kontinuierliche Überwachen des Drucks in einem hydraulischen System des SCR-Katalysatorsystems. Die Differenz zwischen einem maximalen Druck und einem minimalen Druck in einem vorgegebenen Messintervall wird berechnet und die Druckdifferenz mit einem Schwellenwert verglichen. Auf eine Blockierung des Dosierventils wird erkannt, wenn die Druckdifferenz unterhalb des Schwellenwertes liegt. Unter dem hydraulischen System des SCR-Katalysatorsystems wird erfindungsgemäß jenes System verstanden, welches zwischen einer druckerzeugenden Vorrichtung, wie beispielsweise einer Pumpe zum Fördern von Harnstoffwasserlösung aus einem Reduktionsmitteltank und dem Dosierventil des SCR-Katalysatorsystems liegt. Dieses kann einen oder mehrere Druckspeicher, wie beispielsweise Filter oder Leitungen umfassen. Die Ermittlung des Drucks in dem hydraulischen System kann mittels eines in diesem System standardmäßig verbauten Drucksensors erfolgen.The inventive method for fault detection on a metering valve of an SCR catalyst system comprises continuously monitoring the pressure in a hydraulic system of the SCR catalyst system. The difference between a maximum pressure and a minimum pressure in a predetermined measurement interval is calculated and the pressure difference compared to a threshold value. Blocking of the metering valve is detected when the pressure difference is below the threshold value. According to the invention, the hydraulic system of the SCR catalyst system is understood to mean that system which lies between a pressure-generating device, such as a pump for conveying urea water solution from a reducing agent tank, and the metering valve of the SCR catalyst system. This may include one or more pressure accumulators, such as filters or conduits. The determination of the pressure in the hydraulic system can be carried out by means of a standard built-in pressure sensor in this system.
Bevorzugt wird nur auf eine Blockierung des Dosierventils erkannt, wenn eine Ansteuerung des Dosierventils im Messintervall einen festgelegten Minimalwert überschreitet. Hierdurch wird sichergestellt, dass das erfindungsgemäße Verfahren nur bei ausreichender Ansteuerung auf eine Blockierung des Dosierventils schließt, sodass Fehldiagnosen vermieden werden. Die Ansteuerung kann erfindungsgemäß beispielsweise durch ein Tastverhältnis (duty cycle) abgebildet werden. Preferably, it is only recognized that the metering valve is blocked if a triggering of the metering valve in the measuring interval exceeds a specified minimum value. In this way, it is ensured that the method according to the invention only closes upon blocking of the metering valve if there is sufficient control so that misdiagnosis is avoided. The control can be imaged according to the invention, for example, by a duty cycle (duty cycle).
Weiterhin ist es erfindungsgemäß bevorzugt, dass nur auf eine Blockierung des Dosierventils erkannt wird, wenn eine zusätzliche Überwachungsfunktion einen Fehler des Dosierventils meldet, d.h. wenn eine Kombination aus zwei Überwachungsfunktionen einen Fehler des Dosierventils meldet. Bei der zusätzlichen Überwachungsfunktion kann es sich um eine Überwachungsfunktion gemäß dem Stand der Technik handeln, welche die Funktion des Dosierventils aufgrund seines Stromverlaufs diagnostiziert. Hierbei wird die Robustheit der Fehlererkennung am Dosierventil durch Kombination eines bekannten Verfahrens mit dem erfindungsgemäßen Verfahren gesteigert. Furthermore, it is inventively preferred that is detected only on a blockage of the metering valve when an additional monitoring function reports an error of the metering valve, ie when a combination of two monitoring functions reports an error of the metering valve. The additional monitoring function may be a monitoring function according to the prior art, which diagnoses the function of the metering valve on the basis of its current profile. In this case, the robustness of the error detection on the metering valve is increased by combining a known method with the method according to the invention.
Das erfindungsgemäße Computerprogramm führt alle Schritte des erfindungsgemäßen Verfahrens aus, wenn es auf einem Rechengerät abläuft. Da das erfindungsgemäße Verfahren auf der Auswertung eines vorhandenen Sensorsignals basiert und zu seiner Durchführung kein zusätzlicher Sensor erforderlich ist, kann es durch das erfindungsgemäße Computerprogramm in einem vorhandenen SCR-Katalysatorsystem implementiert werden, ohne hieran bauliche Veränderungen vornehmen zu müssen. Hierzu dient das erfindungsgemäße Computerprogrammprodukt Programmcode, der auf einem maschinenlesbaren Träger gespeichert ist zur Durchführung des erfindungsgemäßen Verfahrens, wenn das Programm auf einem Computer eines Steuergeräts ausführt wird. The computer program according to the invention performs all steps of the method according to the invention when it runs on a computing device. Since the method according to the invention is based on the evaluation of an existing sensor signal and no additional sensor is required for its implementation, it can be implemented by the computer program according to the invention in an existing SCR catalyst system, without having to make any structural changes thereto. For this purpose, the inventive computer program product program code, which is stored on a machine-readable carrier for carrying out the method according to the invention, when the program is executed on a computer of a control unit.
Kurze Beschreibung der ZeichnungShort description of the drawing
Ein Ausführungsbeispiel der Erfindung ist in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert. An embodiment of the invention is illustrated in the drawing and explained in more detail in the following description.
Ausführungsform der ErfindungEmbodiment of the invention
Weiterhin wird die Ansteuerung des Dosierventils des SCR-Katalysatorsystems als Tastverhältnis (duty cycle) rDyc in einem Überwachungsschritt
Wenn dieser Vergleich
Weiterhin wird in einer herkömmlichen Dosierventilüberwachung
Sofern in beiden Verfahrensschritten
Das erfindungsgemäße Verfahren erhöht die Robustheit der Fehlererkennung aus der herkömmlichen Fehlerüberwachung
Claims (5)
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DE201210202668 DE102012202668A1 (en) | 2012-02-22 | 2012-02-22 | Method for detecting error at metering valve of selective catalytic reduction catalyst system used in e.g. diesel engine, involves detecting blockage of metering valve when pressure difference is below threshold value |
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DE201210202668 DE102012202668A1 (en) | 2012-02-22 | 2012-02-22 | Method for detecting error at metering valve of selective catalytic reduction catalyst system used in e.g. diesel engine, involves detecting blockage of metering valve when pressure difference is below threshold value |
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DE102012202668A1 true DE102012202668A1 (en) | 2013-08-22 |
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DE201210202668 Pending DE102012202668A1 (en) | 2012-02-22 | 2012-02-22 | Method for detecting error at metering valve of selective catalytic reduction catalyst system used in e.g. diesel engine, involves detecting blockage of metering valve when pressure difference is below threshold value |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
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DE102016205555A1 (en) * | 2016-04-04 | 2017-10-05 | Röchling Automotive SE & Co. KG | SCR device with valve arrangement |
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- 2012-02-22 DE DE201210202668 patent/DE102012202668A1/en active Pending
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
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DE102016205555A1 (en) * | 2016-04-04 | 2017-10-05 | Röchling Automotive SE & Co. KG | SCR device with valve arrangement |
US10024214B2 (en) | 2016-04-04 | 2018-07-17 | Röchling Automotive SE & Co. KG | SCR Device with valve arrangement |
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