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EP1149230A1 - Method and arrangement for purifying an exhaust gas stream of a spark ignition engine flowing in an exhaust gas line - Google Patents

Method and arrangement for purifying an exhaust gas stream of a spark ignition engine flowing in an exhaust gas line

Info

Publication number
EP1149230A1
EP1149230A1 EP00900064A EP00900064A EP1149230A1 EP 1149230 A1 EP1149230 A1 EP 1149230A1 EP 00900064 A EP00900064 A EP 00900064A EP 00900064 A EP00900064 A EP 00900064A EP 1149230 A1 EP1149230 A1 EP 1149230A1
Authority
EP
European Patent Office
Prior art keywords
exhaust gas
particle filter
honeycomb body
coating
reducing agent
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP00900064A
Other languages
German (de)
French (fr)
Inventor
Wolfgang Maus
Rolf BRÜCK
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vitesco Technologies Lohmar Verwaltungs GmbH
Original Assignee
Emitec Gesellschaft fuer Emissionstechnologie mbH
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 Emitec Gesellschaft fuer Emissionstechnologie mbH filed Critical Emitec Gesellschaft fuer Emissionstechnologie mbH
Publication of EP1149230A1 publication Critical patent/EP1149230A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10Exhaust 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
    • F01N3/18Exhaust 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
    • F01N3/20Exhaust 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
    • F01N3/2066Selective catalytic reduction [SCR]
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation 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
    • B01D53/34Chemical or biological purification of waste gases
    • B01D53/92Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9404Removing only nitrogen compounds
    • B01D53/9409Nitrogen oxides
    • B01D53/9431Processes characterised by a specific device
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation 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
    • B01D53/34Chemical or biological purification of waste gases
    • B01D53/92Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9445Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
    • B01D53/9454Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific device
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation 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
    • B01D53/34Chemical or biological purification of waste gases
    • B01D53/92Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9495Controlling the catalytic process
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0814Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0821Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents combined with particulate filters
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0828Exhaust 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
    • F01N3/0835Hydrocarbons
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0828Exhaust 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
    • F01N3/0842Nitrogen oxides
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0828Exhaust 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
    • F01N3/0857Carbon oxides
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01NGAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00Adding substances to exhaust gases
    • F01N2610/02Adding substances to exhaust gases the substance being ammonia or urea
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02BINTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00Other engines
    • F02B75/12Other methods of operation
    • F02B2075/125Direct injection in the combustion chamber for spark ignition engines, i.e. not in pre-combustion chamber
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/10Internal combustion engine [ICE] based vehicles
    • Y02T10/12Improving ICE efficiencies

Definitions

  • the present invention relates to a method and an arrangement for cleaning an exhaust gas stream of a gasoline engine flowing in an exhaust gas line, to which an air / fuel mixture is preferably supplied via direct injection.
  • pollutants essentially hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NO ⁇ ), as well as possibly soot particles.
  • HC hydrocarbons
  • CO carbon monoxide
  • NO ⁇ nitrogen oxides
  • the content of pollutants and soot particles in the exhaust gas mainly depends on the air / fuel ratio supplied. With small air / fuel ratios one speaks of a "rich" mixture composition (air deficit); with large air / fuel ratios one speaks of a "lean” mixture composition (air excess).
  • Soot occurs mainly when burning under extreme air deficiency. Although this condition is not normally achieved in the gasoline engine, it can occur locally due to inhomogeneities, especially during the cold start phase.
  • the soot formation is usually initiated by thermal cracking of the fuel molecules in the absence of oxygen and, with the elimination of hydrogen, leads to the polymerization of carbon-rich macromolecules, which then agglomerate into the final soot particles.
  • the sharp increase in soot when the stoichiometric air ratio is approached follows from the increasing Expansion of the rich mixture zones due to an increase in the injection quantity. Soot formed in rich mixture zones usually hardly burns without further measures.
  • the exhaust gas also contains a relatively large amount of CO and HC, while with air excess CO and HC can be almost completely oxidized up to a certain point.
  • the NO ⁇ content goes through a maximum in the range of slightly lean mixture composition. In this area, however, there is an optimum of the specific fuel consumption for the gasoline engine. So if gasoline engines are set to optimally low consumption, there are high NO ⁇ concentrations in addition to moderate CO and HC concentrations in the exhaust gas. So far, little attention has been paid to the fact that gasoline engines also produce particles, which, however, are usually smaller and have a lower total volume than diesel engines. Nevertheless, such particles can be an environmental burden.
  • the invention is based on the object of specifying measures and devices for improved cleaning of an exhaust gas stream of a gasoline engine flowing in an exhaust line.
  • the method according to the invention for cleaning an exhaust gas stream of a gasoline engine flowing in an exhaust gas line, to which an air / fuel mixture is preferably fed via direct injection is characterized in that the exhaust gas in the exhaust gas line one behind the other has at least one honeycomb body with a catalytically active coating, preferably a three - Path coating, and a particle filter with an at least temporarily storing at least one pollutant component, in particular hydrocarbon (HC), carbon monoxide (CO) and / or nitrogen oxide (NO ⁇ ), through which the coating, whereby an improved cleaning of the exhaust gas can be achieved in an advantageous manner.
  • HC hydrocarbon
  • CO carbon monoxide
  • NO ⁇ nitrogen oxide
  • a reducing agent preferably from a reducing agent reservoir via at least one reducing agent line, for example continuously, is fed to the particle filter.
  • a reducing agent for example ammonia
  • ammonia as a function of a residual NO ⁇ concentration in the exhaust gas behind the honeycomb body almost completely avoids overdosing of the reducing agent, thereby achieving a stoichiometric ratio between the remaining NO ⁇ and reducing agent and advantageously cleaning the exhaust gas containing NO ⁇ Otto engine is improved.
  • Another advantage is that significantly smaller amounts of reducing agents are required than, for example, when reducing agent is injected into an exhaust gas before it flows through a honeycomb body with a catalytically active coating.
  • the reducing agent line preferably ends at the particle filter, the particle filter preferably having an integrated distribution device to which the reducing agent line is connected.
  • an oxidizing agent preferably oxygen (O 2 )
  • O 2 oxygen
  • the coating of the particle filter can at least temporarily store oxygen (O 2 ).
  • Modern gasoline engines usually have electronic engine control or comparable control means.
  • HC hydrocarbon
  • CO carbon monoxide
  • NO ⁇ nitrogen oxide
  • pollutant residues not converted in the honeycomb body can be recognized in an advantageous manner and implemented in the particle filter arranged behind them, which has a correspondingly storing coating, supported by the reducing or oxidizing agents supplied to the filter, the metering of which is controlled, for example, by means of the electronic motor control.
  • the particle filter is preferably regenerated by burning the particles, in particular triggered by engine heat and / or by exothermic reactions in the honeycomb body, preferably at intervals which can be determined, for example, by means of the engine control.
  • the honeycomb body can at the same time form the particle filter at least in partial areas, as a result of which a space-saving design can advantageously be achieved.
  • the single figure schematically shows an arrangement for cleaning an exhaust gas stream of an Otto engine 1 flowing in an exhaust gas line 2, to which an air / fuel mixture is preferably supplied via direct injection.
  • an air / fuel mixture is preferably supplied via direct injection.
  • the flow direction S there is at least one honeycomb body 3 with a catalytically active coating, preferably a three-way catalytic converter, in the exhaust line. and a particle filter 4 with an at least temporarily storing at least one pollutant component, in particular hydrocarbon (HC), carbon monoxide (CO) and or nitrogen oxide (NO ⁇ ).
  • HC hydrocarbon
  • CO carbon monoxide
  • NO ⁇ nitrogen oxide
  • the coating of the particle filter 4 is preferably at least partially designed such that when the gasoline engine 1 is supplied with a rich air / fuel mixture, residual HC and CO which have not been converted in the honeycomb body 3 are stored; and that when the lean engine 1 is supplied with a lean air / fuel mixture, the residual NO ⁇ converted into the honeycomb body 3 is stored.
  • At least one measuring probe 5, 6, 7 is provided, which are arranged between the honeycomb body 3 and the particle filter 4 and, for example, in connection with an electronic motor control, not shown stand, which advantageously includes programs for controlling or regulating the exhaust gas cleaning. In particular, it can be used to determine metered amounts of reducing and / or oxidizing agents to be added.
  • an oxidizing agent or a reducing agent is fed from a reducing agent reservoir 8 via at least one reducing agent line 9 by means of a pump 11 to the particle filter 4 .
  • the particle filter 4 preferably has an integrated distribution device 10, in particular for supplying the reducing agent, which is connected to the reducing agent line 9.
  • Fluid ammonia is preferably used as the reducing agent, which is carried in the reducing agent reservoir 8 and can be supplied as required.
  • the reducing agent can also be carried as a stored precursor, for example urea, in the reducing agent reservoir 8 and, if necessary, in particular pyrolytically, produced and then fed as a fluid to the particle filter 4, in particular via the distribution device 10.
  • a stored precursor for example urea
  • the structure of the particle filter 4 which promotes the deposition of soot particles is preferably a pore structure or a channel structure, wherein in the case of channels these are preferably at least partially offset and / or arranged transversely.
  • the particle filter 4 is arranged at least so closely adjacent behind the honeycomb body 3 that the particles burn, in particular triggered by exothermic reactions in the honeycomb body 3, preferably at determinable intervals.
  • the honeycomb body 3 can also form the particle filter 4 at least in partial areas.
  • honeycomb body 3 and particle filter 4 further components can be provided in the exhaust line 2 of a gasoline engine 1.
  • at least one so-called water trap can be arranged in front of the honeycomb body 3, which keeps the honeycomb body 3 and its catalytic coating as dry as possible in order to be able to bring about the desired oxidation or reduction processes in the honeycomb body 3 even at exhaust gas temperatures of only about 100 ° C. .
  • Water traps therefore contain materials that can collect and store large quantities of water below a certain temperature.
  • an electrically heatable catalyst can also be arranged in the exhaust line 2 in front of the honeycomb body 3 in order to ensure an at least temporarily increased exhaust gas temperature for a catalytic conversion of the pollutants even immediately after the engine has started.
  • the honeycomb body 3 itself can be electrically heated.
  • the present invention is particularly suitable for exhaust systems of gasoline engines.
  • the particle filter 4 advantageously takes on the additional oxidation of residual hydrocarbons (HC) and carbon monoxide (CO) during the cold start phase and, in particular, the supplementary reduction of residual nitrogen oxides (NO ⁇ ) when the gasoline engine 1 is under load. .

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • General Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Environmental & Geological Engineering (AREA)
  • Biomedical Technology (AREA)
  • Toxicology (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
  • Processes For Solid Components From Exhaust (AREA)
  • Filtering Of Dispersed Particles In Gases (AREA)

Abstract

The invention relates to a method and arrangement for purifying an exhaust gas stream of a spark ignition engine (1) flowing in an exhaust gas line (2). An air/fuel mixture is preferably supplied to said spark ignition engine by means of direct injection. For an improved purification, the exhaust gas flows, in succession, through the exhaust gas line (2), through at least one honeycomb body (3) with a catalytically active coating, preferably with a three-way coating, and through a particle filter (4) with a coating which accumulates at least one pollutant component, in particular, hydrocarbon (HC), carbon monoxide (CO) and/or nitrogen oxide (NOx) in an at least temporary manner. The invention is particularly suited for exhaust gas systems of spark ignition engines (1). In addition to its existing task of collecting soot particles, the particle filter (4) advantageously assumes the function of carrying out, in particular, the supplementary oxidation of residual hydrocarbons (HC) as well as carbon monoxide (CO) during the cold start phase, and carries out, in particular, the supplementary reduction of residual nitrogen oxides (NOx) when the spark ignition engine (1) is operated under load.

Description

Verfahren und Anordnung zum Reinigen eines in einem Abgasstrang strömenden Abgasstromes eines Ottomotors Method and arrangement for cleaning an exhaust gas stream of a gasoline engine flowing in an exhaust line

Die vorliegende Erfindung betrifft ein Verfahren und eine Anordnung zum Reinigen eines in einem Abgasstrang strömenden Abgasstromes eines Ottomotors, dem ein Luft/Kraftstoff-Gemisch vorzugsweise über eine Direkteinspritzung zugeführt wird.The present invention relates to a method and an arrangement for cleaning an exhaust gas stream of a gasoline engine flowing in an exhaust gas line, to which an air / fuel mixture is preferably supplied via direct injection.

Bei der Verbrennung von Kohlenwasserstoffen, wie sie beispielsweise in Benzin vorkommen, mit Luft in einem Ottomotor, entstehen neben den Hauptverbrennungsprodukten Kohlenstoffdioxid und Wasserdampf auch Nebenprodukte, insbesondere Schadstoffe, im wesentlichen Kohlenwasserstoffe (HC), Kohlenstoffmonoxid (CO) und Stickoxide (NOχ), sowie gegebenenfalls Rußpartikel. Der Gehalt von Schadstoffen und Rußpartikeln im Abgas hängt überwiegend von dem zugeführten Luft/Kraftstoffverhältnis ab. Bei kleinen Verhältnissen Luft/Kraftstoff spricht man von einer „fetten" Gemischzusammensetzung (Luftunterschuß); bei großen Verhält- nissen Luft/Kraftstoff von einer „mageren" Gemischzusammensetzung (Luftüberschuß).In the combustion of hydrocarbons, such as those found in gasoline, with air in a gasoline engine, in addition to the main combustion products carbon dioxide and water vapor, by-products also arise, in particular pollutants, essentially hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOχ), as well as possibly soot particles. The content of pollutants and soot particles in the exhaust gas mainly depends on the air / fuel ratio supplied. With small air / fuel ratios one speaks of a "rich" mixture composition (air deficit); with large air / fuel ratios one speaks of a "lean" mixture composition (air excess).

Ruß tritt hauptsächlich bei Verbrennung unter extremen Luftunterschuß auf. Diese Bedingung ist zwar normalerweise beim Ottomotor nicht erreicht, kann aber örtlich durch Inhomogenitäten, insbesondere während der Kaltstartphase, auftreten. Die Rußbildung wird in der Regel durch thermisches Cracken der Brennstoffmoleküle unter Sauerstoffmangel eingeleitet und führt unter Abspaltung von Wasserstoff zur Polymerisation von kohlenstoffreichen Makromolekülen, die dann zu den endgültigen Rußteilchen agglomerieren. Die starke Zunahme von Ruß bei Annäherung an das stöchiometrische Luft Verhältnis folgt aus der zunehmenden Ausdehnung der fetten Gemischzonen infolge Erhöhung der Einspritzmenge. In fetten Gemischzonen gebildeter Ruß verbrennt ohne weitere Maßnahmen meist kaum.Soot occurs mainly when burning under extreme air deficiency. Although this condition is not normally achieved in the gasoline engine, it can occur locally due to inhomogeneities, especially during the cold start phase. The soot formation is usually initiated by thermal cracking of the fuel molecules in the absence of oxygen and, with the elimination of hydrogen, leads to the polymerization of carbon-rich macromolecules, which then agglomerate into the final soot particles. The sharp increase in soot when the stoichiometric air ratio is approached follows from the increasing Expansion of the rich mixture zones due to an increase in the injection quantity. Soot formed in rich mixture zones usually hardly burns without further measures.

Damit unverbrannte Rußpartikel nicht die Umwelt belasten, ist beispielsweise aus der DE 41 17 676 AI bekannt, insbesondere im Abgasstrang von Dieselmotoren, wenigstens einen Filter mit einer die Ablagerung von Rußpartikeln fordernden Struktur anzuordnen. Die Regeneration eines solchen Partikelfilters, d.h. die Verbrennung von abgelagerten Rußpartikeln, erfolgt beispielsweise durch zeitweises Zuführen von Kraftstoff und Luft zur Aulheizung des Partikelfilters, so daß auch unter Luftunterschuß gebildete Rußpartikel wieder verbrennen. Es ist auch z. B. aus der DE 40 12 719 AI bekannt, den Filter mit einem zumindest eine Schadstofϊkomponente, insbesondere Kohlenwasserstoff (HC), Kohlenstoffmonoxid (CO) und/oder Stickoxid (NOx) umzusetzenden Katalysator zu versehen.So that unburned soot particles do not pollute the environment, it is known, for example from DE 41 17 676 AI, in particular in the exhaust system of diesel engines, to arrange at least one filter with a structure which requires the deposition of soot particles. The regeneration of such a particle filter, ie the combustion of deposited soot particles, is carried out, for example, by temporarily supplying fuel and air for heating the particle filter, so that soot particles formed under a deficit of air burn again. It is also e.g. B. from DE 40 12 719 AI known to provide the filter with at least one pollutant component, in particular hydrocarbon (HC), carbon monoxide (CO) and / or nitrogen oxide (NO x ) catalyst to be implemented.

Bei einer Verbrennung unter extremen Luftunterschuß enthält das Abgas zudem relativ viel CO und HC, während bei Luftüberschuß bis zu einem gewissen Punkt CO und HC fast vollständig oxidiert werden können. Der Gehalt an NOχ durchläuft ein Maximum im Bereich leicht magerer Gemischzusammensetzung. In diesem Bereich liegt aber für den Ottomotor ein Optimum des spezifischen Verbrauches an Brennstoff. Werden also Ottomotoren auf optimal niedrigen Verbrauch eingestellt, liegen hohe NOχ-Konzentrationen neben mäßigen CO- und HC-Konzentrationen im Abgas vor. Bisher kaum Beachtung gefunden hat dabei die Tatsache, daß auch Ottomotoren Partikel erzeugen, die allerdings meist kleiner sind und mit geringerem Gesamtvolumen entstehen als bei Dieselmotoren. Trotzdem können solche Partikel eine Umweltbelastung sein. Der Erfindung liegt die Aufgabe zugrunde, Maßnahmen und Vorrichtungen zur verbesserten Reinigung eines in einem Abgasstrang strömenden Abgasstromes eines Ottomotors anzugeben.With combustion under extreme air deficiency, the exhaust gas also contains a relatively large amount of CO and HC, while with air excess CO and HC can be almost completely oxidized up to a certain point. The NOχ content goes through a maximum in the range of slightly lean mixture composition. In this area, however, there is an optimum of the specific fuel consumption for the gasoline engine. So if gasoline engines are set to optimally low consumption, there are high NOχ concentrations in addition to moderate CO and HC concentrations in the exhaust gas. So far, little attention has been paid to the fact that gasoline engines also produce particles, which, however, are usually smaller and have a lower total volume than diesel engines. Nevertheless, such particles can be an environmental burden. The invention is based on the object of specifying measures and devices for improved cleaning of an exhaust gas stream of a gasoline engine flowing in an exhaust line.

Diese Aufgabe wird durch ein Verfahren gemäß Anspruch 1 und durch eine Anordnung gemäß Anspruch 12 gelöst. Vorteilhafte Ausgestaltungen und Weiterbildungen sind in den jeweils abhängigen Ansprüchen beschrieben.This object is achieved by a method according to claim 1 and by an arrangement according to claim 12. Advantageous refinements and developments are described in the respective dependent claims.

Das erfindungsgemäße Verfahren zum Reinigen eines in einem Abgasstrang strömenden Abgasstromes eines Ottomotors, dem ein Luft/Kraftstoff-Gemisch vorzugsweise über eine Direkteinspritzung zugeführt wird, zeichnet sich dadurch aus, daß das Abgas im Abgasstrang hintereinander mindestens einen Wabenkörper mit katalytisch aktiver Beschichtung, vorzugsweise einer Drei- Wege-Beschichtung, und einen Partikelfilter mit einer wenigstens zeitweise zumindest eine Schadstoffkomponente, insbesondere Kohlenwasserstoff (HC), Kohlenstoffmonoxid (CO) und/oder Stickoxid (NOχ), speichernden Beschichtung durchströmt, wodurch in vorteilhafter Weise eine verbesserte Reinigung des Abgases erzielbar ist.The method according to the invention for cleaning an exhaust gas stream of a gasoline engine flowing in an exhaust gas line, to which an air / fuel mixture is preferably fed via direct injection, is characterized in that the exhaust gas in the exhaust gas line one behind the other has at least one honeycomb body with a catalytically active coating, preferably a three - Path coating, and a particle filter with an at least temporarily storing at least one pollutant component, in particular hydrocarbon (HC), carbon monoxide (CO) and / or nitrogen oxide (NOχ), through which the coating, whereby an improved cleaning of the exhaust gas can be achieved in an advantageous manner.

Es hat sich nämlich gezeigt, daß bei einer Anordnung eines Partikelfilters mit einer wenigstens zeitweise zumindest eine der Schadstoffkomponenten speichernden Beschichtung hinter mindestens einem Wabenkörper mit einer katalytisch aktiven Beschichtung in überraschender Weise eine verbesserte Reinigung des im Abgasstrang strömenden Abgases sowohl hinsichtlich der Schadstoffkomponenten als auch hinsichtlich gegebenenfalls auftretender Rußpartikel erzielen läßt. So wird für den Fall, daß dem Ottomotor beispielsweise während der Kaltstartphase ein fettes Luft/Kraftstoff-Gemisch zugeführt wird, zur Verbesserung der Abgasreinigung vorgeschlagen, daß die Beschichtung des Partikelfilters nicht im Wabenkörper umgesetztes restliches HC bzw. CO speichert.It has been shown that, in an arrangement of a particle filter with a coating that at least temporarily stores at least one of the pollutant components behind at least one honeycomb body with a catalytically active coating, surprisingly improved cleaning of the exhaust gas flowing in the exhaust line both with regard to the pollutant components and with regard to, if appropriate soot particles can be achieved. For example, in the event that a rich air / fuel mixture is supplied to the gasoline engine during the cold start phase, it is proposed to improve the exhaust gas purification that the coating of the particle filter stores residual HC or CO that has not been converted in the honeycomb body.

Für den Fall, daß dem Ottomotor ein mageres Luft/Kraftstoff-Gemisch zugeführt wird, wird zur Verbesserung der Abgasreinigung vorgeschlagen, daß die Beschichtung des Partikelfilters nicht im Wabenkörper umgesetztes restliches NOχ speichert.In the event that a lean air / fuel mixture is supplied to the gasoline engine, it is proposed to improve the exhaust gas purification that the coating of the particle filter does not store any residual NOχ converted in the honeycomb body.

Dadurch lassen sich in vorteilhafter Weise die jeweils erhöhten Schadstoff- Konzentrationen im Abgas gezielt und nahezu vollständig eliminieren.As a result, the respective increased pollutant concentrations in the exhaust gas can be eliminated in a targeted manner and almost completely.

Zur weiteren Minimierung der Stickoxide (NOχ) wird vorgeschlagen, daß in Abhängigkeit einer restlichen NOχ-Konzentration im Abgas hinter dem Wabenkörper dem Partikelfilter ein Reduktionsmittel, vorzugsweise aus einem Reduktionsmittelreservoir über wenigstens eine Reduktionsmittelleitung, beispielsweise kontinuierlich, zugeführt wird.To further minimize the nitrogen oxides (NOχ), it is proposed that, depending on a remaining NOχ concentration in the exhaust gas behind the honeycomb body, a reducing agent, preferably from a reducing agent reservoir via at least one reducing agent line, for example continuously, is fed to the particle filter.

Alternativ hierzu wird vorgeschlagen, das Reduktionsmittel in Intervallen dem Partikelfilter zuzuführen, insbesondere in Abhängigkeit von im Partikelfilter gespeicherten Mengen an restlichem NOχ.As an alternative to this, it is proposed to supply the reducing agent to the particle filter at intervals, in particular as a function of the amounts of residual NOχ stored in the particle filter.

Die Zuführung eines Reduktionsmittels, beispielsweise Ammoniak, in Abhängigkeit einer restlichen NOχ-Konzentration im Abgas hinter dem Wabenkörper vermeidet fast vollständig Überdosierungen des Reduktionsmittels, wodurch etwa ein stöchiometrisches Verhältnis zwischen restlichem NOχ und Reduktionsmittel erzielt und in vorteilhafter Weise die Reinigung von NOχ enthaltendem Abgas des Ottomotors verbessert wird. Ein weiterer Vorteil besteht darin, daß deutlich geringere Mengen an Reduktionsmitteln benötigt werden als beispielsweise bei einer Eindüsung von Reduktionsmittel in ein Abgas, bevor dieses einen Wabenkörper mit katalytisch aktiver Beschichtung durchströmt.The addition of a reducing agent, for example ammonia, as a function of a residual NOχ concentration in the exhaust gas behind the honeycomb body almost completely avoids overdosing of the reducing agent, thereby achieving a stoichiometric ratio between the remaining NOχ and reducing agent and advantageously cleaning the exhaust gas containing NOχ Otto engine is improved. Another advantage is that significantly smaller amounts of reducing agents are required than, for example, when reducing agent is injected into an exhaust gas before it flows through a honeycomb body with a catalytically active coating.

Erfindungsgemäß bevorzugt endet die Reduktionsmittelleitung am Partikelfilter, wobei vorzugsweise der Partikelfilter eine integrierte Verteileinrichtung aufweist, mit der die Reduktionsmittelleitung verbunden ist.According to the invention, the reducing agent line preferably ends at the particle filter, the particle filter preferably having an integrated distribution device to which the reducing agent line is connected.

Zur weiteren Minimierung der Kohlenwasserstoffe (HC) und des Kohlenstoff- monoxids (CO) wird vorgeschlagen, daß in Abhängigkeit einer restlichen HC-CO- Konzentration im Abgas hinter dem Wabenkörper dem Partikelfilter ein Oxidationsmittel, vorzugsweise Sauerstoff (O2), zugeführt wird.To further minimize the hydrocarbons (HC) and the carbon monoxide (CO), it is proposed that an oxidizing agent, preferably oxygen (O 2 ), be fed to the particle filter depending on a remaining HC-CO concentration in the exhaust gas behind the honeycomb body.

Alternativ und/oder kumulativ kann vorzugsweise die Beschichtung des Partikelfilters wenigstens zeitweise Sauerstoff (O2) speichern.Alternatively and / or cumulatively, the coating of the particle filter can at least temporarily store oxygen (O 2 ).

Die Zuführung eines Oxidationsmittels in Abhängigkeit von restlichen Kohlenwasserstoffe (HC) und restlichem Kohlenstoffmonoxid (CO) vermeidet fast vollständig Überdosierungen, wodurch etwa ein stöchiometrisches Verhältnis zwischen restlichem HC bzw. CO einerseits und dem Oxidationsmittel andererseits erzielt und in vorteilhafter Weise die Reinigung von HC bzw. CO enthaltendem Abgas des Ottomotors verbessert wird.The supply of an oxidizing agent as a function of residual hydrocarbons (HC) and residual carbon monoxide (CO) almost completely avoids overdosing, as a result of which a stoichiometric ratio between residual HC or CO on the one hand and the oxidizing agent on the other hand is achieved and the cleaning of HC or CO-containing exhaust gas from the gasoline engine is improved.

Üblicherweise weisen moderne Ottomotoren eine elektronische Motorsteuerung oder damit vergleichbare Steuer- und Regelmittel auf. Zur verbesserten Steuer- und/oder Regelung der Abgasreinigung beispielsweise durch eine Motorsteuerung wird vorgeschlagen, zwischen Wabenkörper und Partikelfilter wenigstens eine Meßsonde anzuordnen, welche wenigstens eine nicht im Wabenkörper umgesetzte Schadstoffkomponente mißt, wobei vorzugsweise zur Messung der restlichen Schadstoffkomponenten Kohlenwasserstoff (HC), Kohlenstoffmonoxid (CO) und Stickoxid (NOχ) jeweils wenigstens eine Meßsonde vorgesehen ist. Dadurch lassen sind in vorteilhafter Weise nicht im Wabenkörper umgesetzte Schadstoffreste erkennen und im dahinter angeordneten, eine entsprechend speichernde Beschichtung aufweisenden Partikelfilter, unterstützt durch die dem Filter zugeführten Reduktions- bzw. Oxidationsmittel, deren Dosierung beispielsweise mittels der elektronischen Motorsteuerung gesteuert werden, umsetzen.Modern gasoline engines usually have electronic engine control or comparable control means. For improved control and / or regulation of the exhaust gas purification, for example by an engine control, it is proposed to have at least one between the honeycomb body and the particle filter Arrange measuring probe which measures at least one pollutant component not converted in the honeycomb body, preferably at least one measuring probe being provided for measuring the remaining pollutant components hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxide (NOχ). As a result, pollutant residues not converted in the honeycomb body can be recognized in an advantageous manner and implemented in the particle filter arranged behind them, which has a correspondingly storing coating, supported by the reducing or oxidizing agents supplied to the filter, the metering of which is controlled, for example, by means of the electronic motor control.

Erfindungsgemäß bevorzugt wird der Partikelfilter durch Verbrennung der Partikel regeneriert, insbesondere ausgelöst durch Motorwärme und/oder durch exotherme Reaktionen im Wabenkörper, vorzugsweise in beispielsweise mittels der Motorsteuerung bestimmbaren Intervallen.According to the invention, the particle filter is preferably regenerated by burning the particles, in particular triggered by engine heat and / or by exothermic reactions in the honeycomb body, preferably at intervals which can be determined, for example, by means of the engine control.

Alternativ zu der bisher beschriebenen getrennten Anordnung kann der Wabenkörper wenigstens in Teilbereichen zugleich den Partikelfilter bilden, wodurch in vorteilhafter Weise eine platzsparende Bauweise erzielbar ist.As an alternative to the separate arrangement described so far, the honeycomb body can at the same time form the particle filter at least in partial areas, as a result of which a space-saving design can advantageously be achieved.

Weitere Merkmale, Vorteile und Ausgestaltungen der vorliegenden Erfindung werden anhand eines exemplarischen Ausführungsbeispieles und anhand der Zeichnung beschrieben.Further features, advantages and refinements of the present invention are described on the basis of an exemplary embodiment and on the basis of the drawing.

Die einzige Figur zeigt schematisch eine Anordnung zum Reinigen eines in einem Abgasstrang 2 strömenden Abgasstromes eines Ottomotors 1, dem ein Luft/Kraftstoff-Gemisch vorzugsweise über eine Direkteinspritzung zugeführt wird. In Strömungsrichtung S ist im Abgasstrang hintereinander mindestens ein Wabenkörper 3 mit katalytisch aktiver Beschichtung, vorzugsweise ein Drei-Wege-Katalysator, und ein Partikelfilter 4 mit einer wenigstens zeitweise zumindest eine Schadstoffkomponente, insbesondere Kohlenwasserstoff (HC), Kohlenstoffmonoxid (CO) und oder Stickoxid (NOχ), speichernden Beschichtung.The single figure schematically shows an arrangement for cleaning an exhaust gas stream of an Otto engine 1 flowing in an exhaust gas line 2, to which an air / fuel mixture is preferably supplied via direct injection. In the flow direction S there is at least one honeycomb body 3 with a catalytically active coating, preferably a three-way catalytic converter, in the exhaust line. and a particle filter 4 with an at least temporarily storing at least one pollutant component, in particular hydrocarbon (HC), carbon monoxide (CO) and or nitrogen oxide (NOχ).

Die Beschichtung des Partikelfilters 4 ist vorzugsweise wenigstens teilweise so ausgebildet, daß, wenn dem Ottomotor 1 ein fettes Luft/Kraftstoff-Gemisch zugeführt wird, nicht im Wabenkörper 3 umgesetztes restliches HC und CO gespeichert wird; und daß, wenn dem Ottomotor 1 ein mageres Luft/Kraftstoff- Gemisch zugeführt wird, nicht im Wabenkörper 3 umgesetztes restliches NOχ gespeichert wird.The coating of the particle filter 4 is preferably at least partially designed such that when the gasoline engine 1 is supplied with a rich air / fuel mixture, residual HC and CO which have not been converted in the honeycomb body 3 are stored; and that when the lean engine 1 is supplied with a lean air / fuel mixture, the residual NOχ converted into the honeycomb body 3 is stored.

Zur Messung der restlichen Schadstofifkomponenten Kohlenwasserstoff (HC), Kohlenstoffmonoxid (CO) und Stickoxid (NOχ) ist jeweils wenigstens eine Meßsonde 5, 6, 7 vorgesehen, welche zwischen Wabenkörper 3 und Partikelfilter 4 angeordnet sind und beispielsweise mit einer nicht dargestellten elektronischen Motorsteuerung in Verbindung stehen, die in vorteilhafter Weise auch Programme zur Steuer bzw. Regelung der Abgasreinigung beinhaltet. Insbesondere können mit ihr Dosiermengen an ggf. zuzugebenen Reduktions- und/oder Oxidationsmitteln bestimmt werden.To measure the remaining pollutant components hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxide (NOχ) at least one measuring probe 5, 6, 7 is provided, which are arranged between the honeycomb body 3 and the particle filter 4 and, for example, in connection with an electronic motor control, not shown stand, which advantageously includes programs for controlling or regulating the exhaust gas cleaning. In particular, it can be used to determine metered amounts of reducing and / or oxidizing agents to be added.

So wird beispielsweise in Abhängigkeit der gemessenen restlichen HC-CO- Konzentration bzw. einer gemessenen restlichen NOχ-Konzentration im Abgas hinter dem Wabenkörper 3 dem Partikelfilter 4 ein Oxidationsmittel bzw. aus einem Reduktionsmittelreservoier 8 über wenigstens eine Reduktionsmittelleitung 9 mittels einer Pumpe 11 eine Reduktionsmittel zugeführt. Vorzugsweise weist der Partikelfilter 4, insbesondere zur Zuführung des Reduktionsmittels, eine integrierte Verteileinrichtung 10 auf, welche mit der Reduktionsmittelleitung 9 verbunden ist. Bevorzugt wird fluides Ammoniak als Reduktionsmittel verwendet, welches im Reduktionsmittelreservoir 8 mitgeführt und bedarfsweise zugeführt werden kann. Alternativ hierzu kann das Reduktionsmittel auch als gespeicherter Vorläufer, beispielsweise Harnstoff, im Reduktionsmittelreservoir 8 mitgeführt werden und bedarfsweise, insbesondere pyrolytisch, hergestellt und anschließend als Fluid dem Partikelfilter 4, insbesondere über die Verteileinrichtung 10, zugeführt werden.For example, depending on the measured remaining HC-CO concentration or a measured remaining NOχ concentration in the exhaust gas behind the honeycomb body 3, an oxidizing agent or a reducing agent is fed from a reducing agent reservoir 8 via at least one reducing agent line 9 by means of a pump 11 to the particle filter 4 . The particle filter 4 preferably has an integrated distribution device 10, in particular for supplying the reducing agent, which is connected to the reducing agent line 9. Fluid ammonia is preferably used as the reducing agent, which is carried in the reducing agent reservoir 8 and can be supplied as required. As an alternative to this, the reducing agent can also be carried as a stored precursor, for example urea, in the reducing agent reservoir 8 and, if necessary, in particular pyrolytically, produced and then fed as a fluid to the particle filter 4, in particular via the distribution device 10.

Die eine Ablagerung von Rußpartikeln fördernde Struktur des Partikelfilters 4 ist vorzugsweise eine Porenstruktur oder eine Kanalstruktur, wobei im Fall von Kanälen diese vorzugsweise wenigstens teilweise versetzt und/oder quer angeordnete sind. Zur Regeneration des Partikelfilters 4, d.h. zur Verbrennung der in ihm abgelagerten Rußpartikel, ist der Partikelfilter 4 wenigstens so dicht benachbart hinter dem Wabenkörper 3 angeordnet, daß die Partikel insbesondere ausgelöst durch exotherme Reaktionen im Wabenkörper 3, vorzugsweise in bestimmbaren Intervallen, verbrennen.The structure of the particle filter 4 which promotes the deposition of soot particles is preferably a pore structure or a channel structure, wherein in the case of channels these are preferably at least partially offset and / or arranged transversely. For the regeneration of the particle filter 4, i.e. for the combustion of the soot particles deposited in it, the particle filter 4 is arranged at least so closely adjacent behind the honeycomb body 3 that the particles burn, in particular triggered by exothermic reactions in the honeycomb body 3, preferably at determinable intervals.

Erfindungsgemäß bevorzugt kann der Wabenköφer 3 auch wenigstens in Teilbereichen zugleich den Partikelfilter 4 bilden.According to the invention, the honeycomb body 3 can also form the particle filter 4 at least in partial areas.

Es sei noch darauf hingewiesen, daß zu der erfindungsgemäßen Anordnung von Wabenköφer 3 und Partikelfilter 4 weitere Komponenten im Abgasstrang 2 eines Ottomotors 1 vorgesehen werden können. Insbesondere kann vor dem Wabenköφer 3 wenigstens eine sogenannte Wasserfalle angeordnet sein, die den Wabenköφer 3 und seine katalytische Beschichtung möglichst trocken hält, um die gewünschten Oxidations- bzw. Reduktionsprozesse im Wabenköφer 3 auch bei Abgas- Temperaturen von nur etwa 100 °C bewirken zu können. Wasserfallen enthalten deshalb Materialien, welche Wasser unterhalb einer bestimmten Temperatur in großen Mengen auffangen und speichern können. Auch kann im Abgasstrang 2 vor dem Wabenköφer 3 zusätzlich ein elektrisch beheizbarer Katalysator angeordnet sein, um eine wenigstens zeitweise erhöhte Abgas-Temperatur für eine katalytische Umsetzung der Schadstoffe auch unmittelbar nach dem Start des Motors sicherzustellen. Letztlich kann der Wabenköφer 3 selbst elektrisch beheizbar sein.It should also be pointed out that in addition to the arrangement according to the invention of honeycomb body 3 and particle filter 4, further components can be provided in the exhaust line 2 of a gasoline engine 1. In particular, at least one so-called water trap can be arranged in front of the honeycomb body 3, which keeps the honeycomb body 3 and its catalytic coating as dry as possible in order to be able to bring about the desired oxidation or reduction processes in the honeycomb body 3 even at exhaust gas temperatures of only about 100 ° C. . Water traps therefore contain materials that can collect and store large quantities of water below a certain temperature. In addition, an electrically heatable catalyst can also be arranged in the exhaust line 2 in front of the honeycomb body 3 in order to ensure an at least temporarily increased exhaust gas temperature for a catalytic conversion of the pollutants even immediately after the engine has started. Ultimately, the honeycomb body 3 itself can be electrically heated.

Die vorliegende Erfindung eignet sich besonders für Abgasanlagen von Ottomotoren. Dabei übernimmt in vorteilhafter Weise der Partikelfilter 4 neben seiner Aufgabe, gegebenenfalls Rußpartikel abzufangen, während der Kaltstartphase insbesondere die ergänzende Oxidation von restlichen Kohlenwasserstoffen (HC) sowie Kohlenstoffmonoxid (CO) und im Lastbetrieb des Ottomotors 1 insbesondere die ergänzende Reduktion von restlichen Stickoxiden (NOχ). The present invention is particularly suitable for exhaust systems of gasoline engines. In addition to its task of trapping soot particles, the particle filter 4 advantageously takes on the additional oxidation of residual hydrocarbons (HC) and carbon monoxide (CO) during the cold start phase and, in particular, the supplementary reduction of residual nitrogen oxides (NOχ) when the gasoline engine 1 is under load. .

BezugszeichenlisteReference list

OttomotorPetrol engine

AbgasstrangExhaust line

WabenköφerHoneycomb body

PartikelfilterParticle filter

MeßsondeMeasuring probe

MeßsondeMeasuring probe

MeßsondeMeasuring probe

ReduktionsmittelreservoirReductant reservoir

ReduktionsmittelleitungReducing agent line

VerteilereinrichtungDistribution device

Pumpepump

Strömungsrichtung Flow direction

Claims

Patentansprüche claims 1. Verfahren zum Reinigen eines in einem Abgasstrang (2) strömenden Abgasstromes eines Ottomotors (1), dem ein Luft/Kraftstoff-Gemisch vorzugsweise über eine Direkteinspritzung zugeführt wird, dadurch gekennzeichnet, daß das Abgas im Abgasstrang (2) hintereinander mindestens einen Wabenköφer (3) mit katalytisch aktiver Beschichtung, vorzugsweise einer Drei-Wege- Beschichtung, und einen Partikelfilter (4) mit einer wenigstens zeitweise zumindest eine Schadstoffkomponente, insbesondere Kohlenwasserstoff (HC), Kohlenstoffmonoxid (CO) und/oder Stickoxid (NOχ), speichernden Beschichtung durchströmt.1. A method for cleaning an exhaust gas stream of an Otto engine (1) flowing in an exhaust gas line (2), to which an air / fuel mixture is preferably fed via direct injection, characterized in that the exhaust gas in the exhaust gas line (2) one behind the other at least one honeycomb body ( 3) with a catalytically active coating, preferably a three-way coating, and a particle filter (4) with an at least temporarily at least one pollutant component, in particular hydrocarbon (HC), carbon monoxide (CO) and / or nitrogen oxide (NOχ), storing coating . 2. Verfahren nach Anspruch 1, wobei dem Ottomotor (1) ein fettes Luft/Kraftstoff-Gemisch zugeführt wird, dadurch gekennzeichnet, daß die Beschichtung des Partikelfilters (4) nicht im Wabenköφer (3) umgesetztes restliches HC und CO speichert.2. The method according to claim 1, wherein the gasoline engine (1) is fed a rich air / fuel mixture, characterized in that the coating of the particle filter (4) not in the honeycomb body (3) stores residual HC and CO. 3. Verfahren nach Anspruch 1, wobei dem Ottomotor (1) ein mageres Luft/Kraftstoff-Gemisch zugeführt wird, dadurch gekennzeichnet, daß die Beschichtung des Partikelfilters (4) nicht im Wabenköφer (3) umgesetztes restliches NOχ speichert.3. The method according to claim 1, wherein the gasoline engine (1) is fed a lean air / fuel mixture, characterized in that the coating of the particle filter (4) not in the honeycomb body (3) stores residual NOχ. 4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß in Abhängigkeit einer restlichen NOχ-Konzentration im Abgas hinter dem Wabenköφer (3) dem Partikelfilter (4) ein Reduktionsmittel, beispielsweise Ammoniak, zugeführt wird. 4. The method according to any one of claims 1 to 3, characterized in that a reducing agent, for example ammonia, is supplied as a function of a remaining NO (concentration in the exhaust gas behind the honeycomb body (3) to the particle filter (4). 5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, daß das Reduktionsmittel kontinuierlich zugeführt wird.5. The method according to claim 4, characterized in that the reducing agent is fed continuously. 6. Verfahren nach Anspruch 4, dadurch gekennzeichnet, daß das Reduktions- mittel in Intervallen zugeführt wird, insbesondere in Abhängigkeit von im6. The method according to claim 4, characterized in that the reducing agent is supplied at intervals, in particular depending on in Partikelfilter (4) gespeicherten Mengen an restlichem NOχ.Particulate filter (4) stored amounts of residual NOχ. 7. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß in Abhängigkeit einer restlichen HC-CO-Konzentration im Abgas hinter dem Wabenköφer (3) dem Partikelfilter (4) ein Oxidationsmittel, vorzugsweise7. The method according to any one of claims 1 to 3, characterized in that an oxidizing agent, preferably depending on a remaining HC-CO concentration in the exhaust gas behind the honeycomb body (3), the particle filter (4) Sauerstoff (O ), zugeführt wird.Oxygen (O) is supplied. 8. Verfahren nach einem der vorherigen Ansprüche, dadurch gekennzeichnet, daß die Beschichtung des Partikelfilters (4) wenigstens zeitweise Sauerstoff (O ) speichert.8. The method according to any one of the preceding claims, characterized in that the coating of the particle filter (4) at least temporarily stores oxygen (O). 9. Verfahren nach einem der vorherigen Ansprüche, dadurch gekennzeichnet, daß zwischen Wabenköφer (3) und Partikelfilter (4) wenigstens eine Meßsonde angeordnet ist, welche wenigstens eine der nicht im Wabenköφer (3) umgesetzten restlichen Schadstoffkomponenten mißt.9. The method according to any one of the preceding claims, characterized in that between honeycomb body (3) and particle filter (4) at least one measuring probe is arranged, which measures at least one of the remaining pollutant components not implemented in the honeycomb body (3). 10. Verfahren nach Anspruch 9, dadurch gekennzeichnet, daß zur Messung der restlichen Schadstoffkomponenten Kohlenwasserstoff (HC), Kohlenstoffmonoxid (CO) und Stickoxid (NOx) jeweils wenigstens eine Meßsonde (5, 6, 7) vorgesehen ist. 10. The method according to claim 9, characterized in that at least one measuring probe (5, 6, 7) is provided for measuring the remaining pollutant components hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxide (NO x ). 11. Verfahren nach einem der vorherigen Ansprüche, dadurch gekennzeichnet, daß der Partikelfilter (4) durch Verbrennung der Partikel regeneriert wird, insbesondere ausgelöst durch Motorwärme und/oder durch exotherme Reaktionen im Wabenköφer (3), vorzugsweise in bestimmbaren Intervallen.11. The method according to any one of the preceding claims, characterized in that the particle filter (4) is regenerated by combustion of the particles, in particular triggered by engine heat and / or by exothermic reactions in the honeycomb body (3), preferably at determinable intervals. 12. Anordnung zum Reinigen eines in einem Abgasstrang (2) strömenden Abgasstromes eines Ottomotors (1), dem ein Luft/Kraftstoff-Gemisch vorzugsweise über eine Direkteinspritzung zugeführt wird, dadurch gekennzeichnet, daß in Strömungsrichtung (S) des Abgases im Abgasstrang (2) hintereinander mindestens ein Wabenköφer (3) mit katalytisch aktiver Beschichtung, vorzugsweise ein Drei-Wege-Katalysator, und ein Partikelfilter (4) mit einer wenigstens zeitweise zumindest eine Schadstoffkomponente, insbesondere Kohlenwasserstoff (HC), Kohlenstoffmonoxid (CO) und oder Stickoxid (NOχ), speichernden Beschichtung angeordnet sind.12. Arrangement for cleaning an exhaust gas stream of an Otto engine (1) flowing in an exhaust gas line (2), to which an air / fuel mixture is preferably fed via direct injection, characterized in that in the flow direction (S) of the exhaust gas in the exhaust gas line (2) at least one honeycomb body (3) with a catalytically active coating, preferably a three-way catalyst, and a particle filter (4) with at least one at least one pollutant component, in particular hydrocarbon (HC), carbon monoxide (CO) and or nitrogen oxide (NOχ) , storing coating are arranged. 13. Anordnung nach Anspruch 12, wobei dem Ottomotor (1) ein fettes Luft - Kraftstoff-Gemisch zugeführt wird, dadurch gekennzeichnet, daß mittels der Beschichtung des Partikelfilters (4) nicht im Wabenköφer (3) umgesetzter Kohlenwasserstoff (HC) und Kohlenstoffmonoxid (CO) speicherbar sind.13. The arrangement according to claim 12, wherein the gasoline engine (1) is fed a rich air-fuel mixture, characterized in that by means of the coating of the particle filter (4) not in the honeycomb body (3) converted hydrocarbon (HC) and carbon monoxide (CO ) can be saved. 14. Anordnung nach Anspruch 12, wobei dem Ottomotor (1) ein mageres Luft/- Kraftstoff-Gemisch zugeführt wird, dadurch gekennzeichnet, daß mittels der Beschichtung des Partikelfilters (4) nicht im Wabenköφer (3) umgesetzte Stickoxide (NOχ) speicherbar sind. 14. The arrangement according to claim 12, wherein the gasoline engine (1) is fed a lean air / fuel mixture, characterized in that by means of the coating of the particle filter (4) not in the honeycomb body (3) converted nitrogen oxides (NOχ) can be stored. 15. Anordnung nach einem der Ansprüche 12 bis 14, dadurch gekennzeichnet, daß in Abhängigkeit einer restlichen NOχ-Konzentration im Abgas hinter dem Wabenköφer (3) dem Partikelfilter (4) aus einem15. Arrangement according to one of claims 12 to 14, characterized in that depending on a remaining NO restlichen concentration in the exhaust gas behind the honeycomb body (3) the particle filter (4) from one Reduktionsmittelreservoir (8) über wenigstens eine Reduktionsmittelleitung (9) ein Reduktionsmittel, beispielsweise Ammoniak, zuführbar ist.Reducing agent reservoir (8) can be supplied with a reducing agent, for example ammonia, via at least one reducing agent line (9). 16. Anordnung nach Anspruch 15, dadurch gekennzeichnet, daß die Reduktionsmittelleitung (9) am Partikelfilter (4) endet.16. The arrangement according to claim 15, characterized in that the reducing agent line (9) ends at the particle filter (4). 17. Anordnung nach Anspruch 16, dadurch gekennzeichnet, daß der Partikelfilter (4) eine integrierte Verteileinrichtung (10) aufweist, mit der die Reduktionsmittelleitung (9) verbunden ist.17. The arrangement according to claim 16, characterized in that the particle filter (4) has an integrated distribution device (10) with which the reducing agent line (9) is connected. 18. Anordnung nach einem der Ansprüche 12 bis 17, dadurch gekennzeichnet, daß in Abhängigkeit einer restlichen HC-CO-Konzentration im Abgas hinter dem Wabenköφer (3) dem Partikelfilter (4) ein Oxidationsmittel, beispielsweise Sauerstoff (O2), zuführbar ist.18. Arrangement according to one of claims 12 to 17, characterized in that an oxidizing agent, for example oxygen (O 2 ), can be supplied as a function of a remaining HC-CO concentration in the exhaust gas behind the honeycomb body (3). 19. Anordnung nach einem der Ansprüche 12 bis 18, dadurch gekennzeichnet, daß die Beschichtung des Partikelfilters (4) so ausgebildet ist, daß sie wenigstens zeitweise Sauerstoff (O2) speichert.19. Arrangement according to one of claims 12 to 18, characterized in that the coating of the particle filter (4) is designed such that it at least temporarily stores oxygen (O 2 ). 20. Anordnung nach einem der Ansprüche 12 bis 19, dadurch gekennzeichnet, daß zur Messung wenigstens einer der nicht im Wabenköφer (3) umgesetzten restlichen Schadstoffkomponenten zwischen Wabenköφer (3) und20. Arrangement according to one of claims 12 to 19, characterized in that for measuring at least one of the remaining pollutant components not implemented in the honeycomb body (3) between the honeycomb body (3) and Partikelfilter (4) wenigstens eine Meßsonde angeordnet ist. Particle filter (4) at least one measuring probe is arranged. 21. Anordnung nach Anspruch 20, dadurch gekennzeichnet, daß zur Messung der restlichen Schadstoffkomponenten Kohlenwasserstoff (HC), Kohlenstoffmonoxid (CO) und Stickoxid (NOχ) jeweils wenigstens eine Meßsonde (5, 6, 7) vorgesehen ist.21. The arrangement according to claim 20, characterized in that at least one measuring probe (5, 6, 7) is provided for measuring the remaining pollutant components hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxide (NOχ). 22. Anordnung nach einem der Ansprüche 12 bis 21, dadurch gekennzeichnet, daß der Partikelfilter (4) ausgelöst durch Motorwärme und/oder durch exotherme Reaktionen im Wabenköφers (3) regenerierbar ist, vorzugsweise in bestimmbaren Intervallen.22. Arrangement according to one of claims 12 to 21, characterized in that the particle filter (4) triggered by engine heat and / or by exothermic reactions in the honeycomb body (3) can be regenerated, preferably at determinable intervals. 23. Anordnung nach einem der Ansprüche 12 bis 22, dadurch gekennzeichnet, daß der Wabenköφer (3) wenigstens in Teilbereichen zugleich den Partikelfilter (4) bildet. 23. Arrangement according to one of claims 12 to 22, characterized in that the honeycomb body (3) at least in partial areas forms the particle filter (4).
EP00900064A 1999-01-18 2000-01-05 Method and arrangement for purifying an exhaust gas stream of a spark ignition engine flowing in an exhaust gas line Withdrawn EP1149230A1 (en)

Applications Claiming Priority (3)

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DE19901760 1999-01-18
DE19901760A DE19901760A1 (en) 1999-01-18 1999-01-18 Method and arrangement for cleaning an exhaust gas stream of a gasoline engine flowing in an exhaust line
PCT/EP2000/000047 WO2000042302A1 (en) 1999-01-18 2000-01-05 Method and arrangement for purifying an exhaust gas stream of a spark ignition engine flowing in an exhaust gas line

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EP (1) EP1149230A1 (en)
JP (1) JP2002535531A (en)
KR (1) KR20010101549A (en)
CN (1) CN1336981A (en)
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WO2000042302A1 (en) 2000-07-20
AU1865700A (en) 2000-08-01
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CN1336981A (en) 2002-02-20
US20020011069A1 (en) 2002-01-31
DE19901760A1 (en) 2000-07-27

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