DE19929042A1 - Controlling regeneration phase of a nitrogen oxides storage catalyst involves using measured signal of exhaust gas sensor connected to storage catalyst in exhaust gas pipe to determine ammonia content - Google Patents

Controlling regeneration phase of a nitrogen oxides storage catalyst involves using measured signal of exhaust gas sensor connected to storage catalyst in exhaust gas pipe to determine ammonia content

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Publication number
DE19929042A1
DE19929042A1 DE1999129042 DE19929042A DE19929042A1 DE 19929042 A1 DE19929042 A1 DE 19929042A1 DE 1999129042 DE1999129042 DE 1999129042 DE 19929042 A DE19929042 A DE 19929042A DE 19929042 A1 DE19929042 A1 DE 19929042A1
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Prior art keywords
exhaust gas
storage catalyst
gas sensor
sensor
regeneration
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DE1999129042
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German (de)
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Jens Papajewski
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Audi AG
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Audi AG
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Priority to DE1999129042 priority Critical patent/DE19929042A1/en
Publication of DE19929042A1 publication Critical patent/DE19929042A1/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
    • 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
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0828—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents characterised by the absorbed or adsorbed substances
    • F01N3/0842—Nitrogen oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B01D53/9431—Processes characterised by a specific device
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9495—Controlling the catalytic process
    • 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
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
    • 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
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0871—Regulation of absorbents or adsorbents, e.g. purging
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/027—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus
    • F02D41/0275—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus the exhaust gas treating apparatus being a NOx trap or adsorbent
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1439—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the position of the sensor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/146—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an NOx content or concentration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D2041/1468—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an ammonia content or concentration of the exhaust gases

Abstract

Process for controlling the regeneration phase of a nitrogen oxides storage catalyst comprises using the measured signal of an exhaust gas sensor (6) connected to the storage catalyst (4) in the exhaust gas pipe (2) to determine the NH3 content in the exhaust gas to define the end of the regeneration phases. Preferred Features: When the measured signal of the exhaust gas sensor at the end of the regeneration phases exceeds a determined threshold value, a fuel-air ratio lambda is adjusted to more than 1 in the exhaust gas. The exhaust gas sensor is maintained at a constant temperature of approximately 200 deg C.

Description

Die vorliegende Erfindung betrifft ein Verfahren zur Steuerung der Regene­ rationsphasen eines NOX-Speicherkatalysators.The present invention relates to a method for controlling the regeneration phases of a NO x storage catalyst.

NOX-Speicherkatalysatoren werden beispielsweise bei Brennkraftmaschinen eingesetzt, die mit magerer Verbrennung, das heißt einem Kraftstoff-zu-Luft- Verhältnis Lambda größer 1, betrieben werden, um die geforderten Abgas­ grenzwerte einhalten zu können. Dabei können die Speicherkatalysatoren die bei einer mageren Verbrennung erzeugten NOX-Verbindungen bis zum Erreichen ihrer Speicherkapazität adsorbieren. Ist diese Speicherkapazität erreicht, so müssen die gespeicherten NOX-Verbindungen durch kurzzeitiges Betreiben der Brennkraftmaschine mit fetter Verbrennung, das heißt einem Kraftstoff-zu-Luft-Verhältnis Lambda kleiner 1, wieder abgebaut werden, um den Speicherkatalysator zu regenerieren.NO x storage catalytic converters are used, for example, in internal combustion engines which are operated with lean combustion, that is to say a fuel-to-air ratio lambda greater than 1, in order to be able to comply with the required exhaust gas limit values. The storage catalytic converters can adsorb the NO x compounds generated during lean combustion until their storage capacity is reached. If this storage capacity is reached, the stored NO x connections must be broken down again by briefly operating the internal combustion engine with rich combustion, that is to say a fuel-to-air ratio lambda less than 1, in order to regenerate the storage catalytic converter.

Aus der Druckschrift DE 196 07 151 C1 ist ein Verfahren zur Regeneration eines NOX-Speicherkatalysators bekannt, wobei während der Regenerati­ onsphase die aktuelle Beladung des Speicherkatalysators ermittelt wird, um die Regenerationsphase rechtzeitig abzubrechen. Dazu wird die Beladung des Speicherkatalysators, die von dem Speicherwirkungsgrad, der Kataly­ satortemperatur und der bereits erfolgten Anzahl von Regenerationsphasen abhängig ist, um einen Wert aus einem Kennfeld dekrementiert und wird die Regenerationsphase beendet, wenn die aktuelle Beladung des Speicherka­ talysators unter einen vorgegebenen Schwellenwert fällt.From the document DE 196 07 151 C1, a method for the regeneration of a NO x storage catalytic converter is known, the current loading of the storage catalytic converter being determined during the regeneration phase in order to terminate the regeneration phase in good time. For this purpose, the loading of the storage catalytic converter, which is dependent on the storage efficiency, the catalyst temperature and the number of regeneration phases that have already taken place, is decremented by a value from a map and the regeneration phase is ended when the current loading of the storage catalytic converter falls below a predetermined threshold value .

Zudem ist aus der Druckschrift DE 197 05 335 C1 eine Brennkraftmaschine mit einem Speicherkatalysator und ein Verfahren zur Regeneration des Speicherkatalysators bekannt. In addition, an internal combustion engine is known from the publication DE 197 05 335 C1 with a storage catalyst and a method for regeneration of the Storage catalyst known.  

Bei dieser Brennkraftmaschine wird das Abgas über den Abgastrakt zu ei­ nem Speicherkatalysator und von dem Speicherkatalysator zu einem Abgas­ sensor geführt, wobei der Abgassensor die Konzentration von Kohlenwas­ serstoffen oder reduzierenden Abgaskomponenten, wie zum Beispiel Koh­ lenmonoxid und Wasserdampf mißt. Zwischen der Brennkraftmaschine und dem Speicherkatalysator ist dort zudem eine Lambdasonde im Abgastrakt vorgesehen, die zur Bestimmung des Kraftstoff-zu-Luft-Verhältnisses vor dem Speicherkatalysator dient.In this internal combustion engine, the exhaust gas becomes egg via the exhaust tract nem storage catalyst and from the storage catalyst to an exhaust gas sensor led, the exhaust gas sensor the concentration of coal water or reducing exhaust gas components, such as Koh measures lenmonoxide and water vapor. Between the engine and there is also a lambda probe in the exhaust tract of the storage catalytic converter provided to determine the fuel-to-air ratio before serves the storage catalyst.

Und bei diesem Verfahren werden die Regenerationsphasen zu vorgegebe­ nen Zeitpunkten durchgeführt, wobei die Regenerationsphasen auch dort immer dann abgeschlossen werden, wenn die NOX-Beladung des Speicher­ katalysators einen vorgegebenen Grenzwert unterschreitet.And in this method, the regeneration phases are carried out at predetermined times, the regeneration phases also being completed there when the NO x loading of the storage catalytic converter falls below a predetermined limit value.

Ausgehend von diesem Stand der Technik ist es Aufgabe der Erfindung, ein verbessertes Verfahren zur Steuerung der Regenerationsphasen eines NOX- Speicherkatalysators zur Verfügung zu stellen, das auf einfache Weise eine sichere Einhaltung der Abgasgrenzwerte und eine bedarfsgerechte Regene­ ration des NOX-Speicherkatalysators gewährleistet.Starting from this prior art, it is an NO X object of the invention, an improved method for controlling the regeneration phases - to provide storage catalyst is available that easily secure compliance with the emission limits, and needs-based Regene ration of the NO x storage catalyst guaranteed.

Gelöst wird die Aufgabe, indem das Meßsignal eines dem NOX-Speicher­ katalysators im Abgasstrang nachgeschalteten Abgassensors zur Ermittlung von NH3 im Abgas verwendet wird, um das Ende der Regenerationsphasen zu definieren. Hierbei spielt es eine wichtige Rolle, daß am Ende der Rege­ nerationsphasen kurz vor dem Durchbruch von CO (Kohlenmonoxid) NH3 (Ammoniak) auftritt und dieses Auftreten von NH3 bei der Steuerung der Re­ generationsphasen als Abschaltkriterium verwendet werden kann. Damit wird einerseits erreicht, daß die Regenerationsphasen optimal ausgenutzt werden, um den NOX-Speicherkatalysator vollständig zu entleeren auf diese Weise den Speicherwirkungsgrad zu erhalten, und andererseits erreicht, daß Durchbrüche von Kohlenmonoxid sowie von unverbrannten Kohlenwasser­ stoffen, welche die Einhaltung der Abgasgrenzwerte gefährden, vermieden werden.The object is achieved by using the measurement signal of an exhaust gas sensor connected downstream of the NO x storage catalytic converter in the exhaust line to determine NH 3 in the exhaust gas in order to define the end of the regeneration phases. It plays an important role that at the end of the regeneration phases shortly before the breakthrough of CO (carbon monoxide) NH 3 (ammonia) occurs and this occurrence of NH 3 can be used as a switch-off criterion in the control of the regeneration phases. On the one hand, this ensures that the regeneration phases are optimally used to completely empty the NO x storage catalytic converter in this way to maintain the storage efficiency, and on the other hand that breakthroughs of carbon monoxide and unburned hydrocarbons, which endanger compliance with the exhaust gas limit values, be avoided.

Übersteigt das Meßsignal des Abgassensors zur Ermittlung von NH3 am En­ de der Regenerationsphasen einen bestimmten Schwellenwert, so wird im Abgas ein Kraftstoff-zu-Luft-Verhältnis Lambda größer 1 eingestellt. Damit werden die Regenerationsphasen beendet und neue Adsorptionsphasen ge­ startet.If the measurement signal of the exhaust gas sensor for determining NH 3 at the end of the regeneration phases exceeds a certain threshold value, a fuel-to-air ratio lambda greater than 1 is set in the exhaust gas. This ends the regeneration phases and starts new adsorption phases.

Wird während der Regenerationsphasen, bei denen im Abgas ein Kraftstoff- zu-Luft-Verhältnis Lambda kleiner 1 vorliegt ein NOX-Sensor als Abgassen­ sor zur Ermittlung von NH3 im Abgas verwendet, wobei dessen Queremp­ findlichkeit genutzt wird, so können zusätzliche und aufwendige Abgassen­ soren zur Ermittlung von NH3 im Abgas entfallen. Denn der NOX-Sensor kann bei diesem Kraftstoff-zu-Luft-Verhältnis aufgrund seiner Querempfind­ lichkeit sowohl für NOX als auch für NH3 im Abgas ein Meßsignal ausgeben. Während der Adsorptionsphasen des NOX-Speicherkatalysators, bei denen im Abgas ein Kraftstoff-zu-Luft-Verhältnis Lambda größer 1 vorliegt - dies ist sein eigentlicher Betriebsbereich - weist der NOX-Sensor hingegen keine Querempfindlichkeit auf, da dann kein NH3 im Abgas auftritt.If during the regeneration phases in which there is a fuel-to-air ratio lambda less than 1 in the exhaust gas, a NO x sensor is used as an exhaust gas sensor for determining NH 3 in the exhaust gas, the transverse sensitivity of which is used, so additional and complex measures can be taken Exhaust gas sensors for determining NH 3 in the exhaust gas are eliminated. Because the NO x sensor can output a measurement signal in this fuel-to-air ratio due to its cross sensitivity both for NO x and for NH 3 in the exhaust gas. During the adsorption phases of the NO x storage catalytic converter, in which there is a fuel-to-air ratio lambda greater than 1 in the exhaust gas - this is its actual operating range - the NO x sensor, on the other hand, has no cross-sensitivity since there is no NH 3 in the exhaust gas occurs.

Zweckmäßig wird die Querempfindlichkeit des NOX-Sensors dabei genutzt, indem in Abhängigkeit von verschiedenen Parametern der Brennkraftma­ schine das von dem NOX-Sensor ermittelte NOX vom NH3 im Abgas unter­ schieden wird.Suitably, the cross-sensitivity of the NOx sensor is used in this by machine in dependence on various parameters of the internal combustion is detected by the NOx sensor NO X by the NH 3 in the exhaust gas differences.

Um eine möglichst genaue Messung von NOX bzw. NH3 im Abgas zu er­ möglichen, wird der Abgassensor auf einer konstanten Temperatur von ca. 200 Grad Celsius gehalten, damit thermische Einflüsse bei der Messung weitgehend eliminiert werden.In order to enable the most accurate measurement of NO x or NH 3 in the exhaust gas, the exhaust gas sensor is kept at a constant temperature of approx. 200 degrees Celsius so that thermal influences during the measurement are largely eliminated.

Die vorliegende Erfindung wird unter Bezugnahme auf die nachfolgenden Zeichnungsfiguren näher erläutert. Es zeigen:The present invention will be described with reference to the following Drawing figures explained in more detail. Show it:

Fig. 1 eine schematische Anordnung einer Brennkraftmaschine mit einem NOX-Speicherkatalysator; und Fig. 1 shows a schematic arrangement of an internal combustion engine having an NO x storage catalyst; and

Fig. 2 ein gegen Ende einer Regenerationsphase gemessenes Ab­ gasspektrum mit NH3 und CO. Fig. 2 measured towards the end of a regeneration phase from gas spectrum with NH 3 and CO.

Die in Fig. 1 gezeigte Brennkraftmaschine 1 führt ihr Abgas zur Abgas­ nachbehandlung über einen Abgastrakt 2 zu einem Dreiwegekatalysator 3 und von dem Dreiwegekatalysator 3 zu einem NOX-Speicherkatalysator 4. The internal combustion engine 1 shown in Fig. 1 performs its exhaust gas after-treatment to the exhaust gas via an exhaust manifold 2 to a three-way catalyst 3 and the three way catalyst 3 to a NO x storage catalyst. 4

Stromauf des Dreiwegekatalysators 3 sowie des NOX-Speicherkatalysators 4 ist im Abgastrakt 2 eine Lambdasonde 5 vorgesehen, durch welche der Wert des aktuellen Kraftstoff-zu-Luft-Verhältnisses bestimmt wird.Upstream of the three-way catalytic converter 3 and the NO x storage catalytic converter 4 , a lambda probe 5 is provided in the exhaust tract 2 , by means of which the value of the current fuel-to-air ratio is determined.

Stromab des NOX-Speicherkatalysators 4 ist im Abgastrakt 2 ein Abgassen­ sor 6 vorgesehen. Als Abgassensor 6 wird hier ein herkömmlicher NOX- Sensor verwendet. Der Abgassensor 6 dient während der Adsorptionspha­ sen des NOX-Speicherkatalysators 4 allein zur Ermittlung von NOX im Abgas und während der Regenerationsphasen des NOX-Speicherkatalysators 4 sowohl zur Ermittlung von NOX als auch von NH3 im Abgas.Downstream of the NO x storage catalytic converter 4 , an exhaust gas sensor 6 is provided in the exhaust tract 2 . A conventional NO x sensor is used here as the exhaust gas sensor 6 . The exhaust gas sensor 6 is used during the Adsorptionspha sen of the NO X storage catalyst 4 solely for determining NO X in the exhaust gas and during the regeneration phases of the NO X storage catalyst 4 both for determining NO X and NH 3 in the exhaust gas.

Die Meßsignale der Lambdasonde 5 und des Abgassensors 6 sind via Steu­ erleitungen zu einem Steuergerät 7 geführt, wo sie verarbeitet und zur Steuerung der Brennkraftmaschine 1 verwendet werden. Außerdem gehen auch von der Brennkraftmaschine 1 eine Reihe von Steuerleitungen aus, die verschiedene andere Parameter der Brennkraftmaschine 1, wie zum Beispiel Drehzahl, Luftmenge, Last, Temperatur, usw. zu dem Steuergerät 7 liefern.The measurement signals of the lambda probe 5 and the exhaust gas sensor 6 are guided via control lines to a control unit 7 , where they are processed and used to control the internal combustion engine 1 . In addition, a number of control lines go out also by the internal combustion engine 1, various other parameters of the internal combustion engine 1, such as rotational speed, air volume, load, temperature, etc. provide to the controller. 7

Während der Adsorptionsphasen speichert der NOX-Speicherkatalysator 4 die im Abgas befindlichen NOX-Verbindungen, bis das Steuergerät 7 in Ab­ hängigkeit von der Luftmenge, der Last oder sonstigen Parametern, die das Ende der Speicherkapazität implizieren, den Beginn einen neuen Regenera­ tionsphase einleitet.During the adsorption phase stores the NOx storage catalytic converter 4, in the exhaust gas NO x compounds, to the control device 7 dependence, the beginning initiates in from the air amount, load, or other parameters, that imply the end of the storage capacity of a new regenerator tion phase .

Und während der Regenerationsphasen wird das im NOX-Speicher­ katalysator 4 gespeicherte NOX wieder abgebaut. Bei einer vollständigen Regenerierung des NOX-Speicherkatalysators 4 tritt durch einen Überschuß an H2 (Wasserstoff) gebildetes NH3 im Abgas auf. Das NH3 führt zu einem Ansprechen des Abgassensors 6, der dann ein Meßsignal an das Steuerge­ rät 7 ausgibt, woraufhin das Ende der Regenerationsphase eingeleitet wird. Auf diese Weise kann das Regenerationsende rechtzeitig ermittelt werden, da erst im Anschluß an das Auftreten von NH3 im Abgas ein zeitverzögertes Durchbrechen von CO (Kohlenmonoxid) erfolgt. Diese Zeitverzögerung Δt kann durch eine Verringerung des Kraftstoff-zu-Luft-Verhältnisses Lambda begünstigt werden, da dann auch das Verhältnis von H2 zu CO ansteigt. And during the regeneration phases the stored in the NOx storage catalyst 4 NO X is reduced again. When the NO x storage catalytic converter 4 is completely regenerated, NH 3 formed in the exhaust gas due to an excess of H 2 (hydrogen). The NH 3 leads to a response of the exhaust gas sensor 6 , which then advises a measurement signal to the Steuerge 7 outputs, whereupon the end of the regeneration phase is initiated. In this way, the end of regeneration can be determined in good time, since a delayed breakdown of CO (carbon monoxide) occurs only after the occurrence of NH 3 in the exhaust gas. This time delay .DELTA.t can be favored by reducing the fuel-to-air ratio lambda, since the ratio of H 2 to CO then also increases.

Das gegen Ende einer Regenerationsphase vorliegende Abgasspektrum mit NH3 und CO sowie die zwischen den Durchbrüchen von NH3 und CO lie­ gende Zeitverzögerung Δt ist zur Verdeutlichung in Fig. 2 dargestellt. Erfin­ dungsgemäß wird die Regenerationsphase unmittelbar nach dem Auftreten des NH3, das heißt rechtzeitig vor dem Auftreten des CO beendet.The exhaust gas spectrum with NH 3 and CO present at the end of a regeneration phase and the time delay Δt lying between the breakthroughs of NH 3 and CO are shown in FIG. 2 for clarification. According to the invention, the regeneration phase is ended immediately after the occurrence of the NH 3 , ie in good time before the occurrence of the CO.

Claims (5)

1. Verfahren zur Steuerung der Regenerationsphasen eines NOX- Speicherkatalysators, dadurch gekennzeichnet, daß das Meßsignal eines dem NOX-Speicherkatalysators (4) im Ab­ gasstrang (2) nachgeschalteten Abgassensors (6) zur Ermittlung von NH3 im Abgas verwendet wird, um das Ende der Regenerationsphasen zu definieren.1. A method for controlling the regeneration phases of a NO X - storage catalytic converter, characterized in that the measuring signal (4) from gas line (2) downstream exhaust gas sensor (6) for determining NH 3 used in the exhaust gas of the NO X storage catalytic converter, in order to define the end of the regeneration phases. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß dann, wenn das Meßsignal des Abgassensors (6) am Ende der Regenerationspha­ sen einen bestimmten Schwellenwert übersteigt, im Abgas ein Kraft­ stoff-zu-Luft-Verhältnis Lambda größer 1 eingestellt wird.2. The method according to claim 1, characterized in that when the measurement signal of the exhaust gas sensor ( 6 ) at the end of the regeneration phase sen exceeds a certain threshold value, a fuel-to-air ratio lambda greater than 1 is set in the exhaust gas. 3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß wäh­ rend der Regenerationsphasen, bei denen im Abgas ein Kraftstoff-zu- Luft-Verhältnis Lambda kleiner 1 vorliegt, ein NOX-Sensor als Abgas­ sensor (6) zur Ermittlung von NH3 im Abgas verwendet wird, wobei dessen Querempfindlichkeit genutzt wird.3. The method according to claim 1 or 2, characterized in that during the regeneration phases in which there is a fuel-to-air ratio lambda less than 1 in the exhaust gas, a NO x sensor as exhaust gas sensor ( 6 ) for determining NH 3 is used in the exhaust gas, whereby its cross-sensitivity is used. 4. Verfahren nach Anspruch 3, dadurch gekennzeichnet, daß die Querempfindlichkeit des NOX-Sensors genutzt wird, indem in Abhän­ gigkeit von verschiedenen Parametern der Brennkraftmaschine (1) das von dem NOX-Sensor ermittelte NOX vom NH3 im Abgas unterschieden wird. 4. The method according to claim 3, characterized in that the cross-sensitivity of the NOx sensor is used by the various parameters of the internal combustion engine (1) is detected by the NOx sensor NO X by the NH 3 differed in the exhaust gas dependence in depen . 5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß der Abgassensor (6) auf einer konstanten Temperatur von ca. 200 Grad Celsius gehalten wird.5. The method according to any one of claims 1 to 4, characterized in that the exhaust gas sensor ( 6 ) is kept at a constant temperature of approximately 200 degrees Celsius.
DE1999129042 1999-06-25 1999-06-25 Controlling regeneration phase of a nitrogen oxides storage catalyst involves using measured signal of exhaust gas sensor connected to storage catalyst in exhaust gas pipe to determine ammonia content Withdrawn DE19929042A1 (en)

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DE1999129042 DE19929042A1 (en) 1999-06-25 1999-06-25 Controlling regeneration phase of a nitrogen oxides storage catalyst involves using measured signal of exhaust gas sensor connected to storage catalyst in exhaust gas pipe to determine ammonia content

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WO2009053814A2 (en) * 2007-10-24 2009-04-30 Toyota Jidosha Kabushiki Kaisha Air-fuel ratio control apparatus and air-fuel ratio control method for internal combustion engine
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EP1413728A2 (en) * 2002-10-23 2004-04-28 Volkswagen Aktiengesellschaft Controller and method for controlling a NOX-sensor arranged in an exhaust gas channel of an internal combustion engine
EP1413728A3 (en) * 2002-10-23 2008-03-05 Volkswagen Aktiengesellschaft Controller and method for controlling a NOX-sensor arranged in an exhaust gas channel of an internal combustion engine
WO2009053814A2 (en) * 2007-10-24 2009-04-30 Toyota Jidosha Kabushiki Kaisha Air-fuel ratio control apparatus and air-fuel ratio control method for internal combustion engine
WO2009053814A3 (en) * 2007-10-24 2009-07-23 Toyota Motor Co Ltd Air-fuel ratio control apparatus and air-fuel ratio control method for internal combustion engine
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US8249793B2 (en) 2007-10-24 2012-08-21 Toyota Jidosha Kabushiki Kaisha Air-fuel ratio control apparatus and air-fuel ratio control method for internal combustion engine
CN101790631B (en) * 2007-10-24 2013-09-04 丰田自动车株式会社 Air-fuel ratio control apparatus and air-fuel ratio control method for internal combustion engine
DE102019208254A1 (en) * 2019-06-06 2020-12-10 Vitesco Technologies GmbH Method for determining the nitrogen oxide content and / or ammonia content in the exhaust gas of an internal combustion engine and exhaust system
DE102019208254B4 (en) 2019-06-06 2021-08-26 Vitesco Technologies GmbH Method for determining the nitrogen oxide content and / or ammonia content and carbon monoxide content in the exhaust gas of an internal combustion engine and exhaust system
US11725602B2 (en) 2019-06-06 2023-08-15 Vitesco Technologies GmbH Method for ascertaining the nitrogen oxide fraction and/or ammonia fraction in the exhaust gas of an internal combustion engine

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