EP3421775B1 - Method for cleaning an exhaust gas recirculation line and/or an exhaust gas recircvulation cooler - Google Patents

Method for cleaning an exhaust gas recirculation line and/or an exhaust gas recircvulation cooler Download PDF

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Publication number
EP3421775B1
EP3421775B1 EP18179480.1A EP18179480A EP3421775B1 EP 3421775 B1 EP3421775 B1 EP 3421775B1 EP 18179480 A EP18179480 A EP 18179480A EP 3421775 B1 EP3421775 B1 EP 3421775B1
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EP
European Patent Office
Prior art keywords
exhaust gas
gas recirculation
recirculation line
internal combustion
combustion engine
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EP18179480.1A
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German (de)
French (fr)
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EP3421775A1 (en
Inventor
Tim VON HÖRSTEN
Andreas ESCHRICH
Jan KUSCHEL
Jörg LANDWEHR
Vincent HÖFLER
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Volkswagen AG
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Volkswagen AG
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Publication of EP3421775A1 publication Critical patent/EP3421775A1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/22—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with coolers in the recirculation passage
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B77/00—Component parts, details or accessories, not otherwise provided for
    • F02B77/04—Cleaning of, preventing corrosion or erosion in, or preventing unwanted deposits in, combustion engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/36—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with means for adding fluids other than exhaust gas to the recirculation passage; with reformers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/49—Detecting, diagnosing or indicating an abnormal function of the EGR system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/50—Arrangements or methods for preventing or reducing deposits, corrosion or wear caused by impurities
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28G—CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS
    • F28G15/00—Details
    • F28G15/003—Control arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28G—CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS
    • F28G9/00—Cleaning by flushing or washing, e.g. with chemical solvents
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/02—EGR systems specially adapted for supercharged engines

Definitions

  • the invention relates to a method for cleaning an exhaust gas recirculation line according to the preamble of the independent claim.
  • Exhaust gas aftertreatment systems are currently used in diesel engines which have an oxidation catalytic converter or NOx storage catalytic converter, a catalytic converter for the selective catalytic reduction of nitrogen oxides (SCR catalytic converter) and a particle filter for separating soot particles and, if necessary, further catalytic converters.
  • Ammonia is preferably used as the reducing agent.
  • a synthetic, aqueous urea solution is usually used in vehicles, which is mixed with the hot exhaust gas flow in a mixing device upstream of the SCR catalytic converter. As a result of this mixing, the aqueous urea solution is heated, with the aqueous urea solution releasing ammonia in the exhaust gas duct.
  • a commercially available, aqueous urea solution is generally composed of 32.5% urea and 67.5% water.
  • One way of reducing the raw emissions of an internal combustion engine is to recirculate exhaust gas into the fresh air system of the internal combustion engine.
  • the combustion temperature in the combustion chambers of the internal combustion engine can be lowered and thus in particular the formation of nitrogen oxide can be reduced.
  • High-pressure exhaust gas recirculation systems are known in which the exhaust gas immediately after an outlet of the Internal combustion engine discharged from the exhaust duct and the intake air is supplied immediately before entering the combustion chamber of the internal combustion engine.
  • low-pressure exhaust gas recirculation systems are known in which the exhaust gas of the internal combustion engine is tapped from the exhaust gas duct downstream of a turbine of the exhaust gas turbocharger and downstream of an exhaust gas treatment component, in particular a particle filter, and fed to the air supply system upstream of a compressor.
  • an exhaust gas recirculation cooler is generally provided in a low-pressure exhaust gas recirculation, with which the exhaust gas temperature of the recirculated exhaust gas is reduced.
  • deposits can form in the exhaust gas recirculation, which can reduce the line cross-section of the exhaust gas recirculation line and disrupt the function of an exhaust gas recirculation valve. This can lead to individual components of the exhaust gas recirculation having to be replaced because the components cannot be cleaned without dismantling and functional reliability is no longer guaranteed.
  • the FR 2 885 178 A1 discloses an internal combustion engine with an exhaust system and an intake system, the exhaust system being connected to the intake system via an exhaust gas recirculation system.
  • an exhaust flap is closed and a cleaning fluid is introduced into the exhaust gas duct in order to flush the exhaust gas recirculation line.
  • JP 2017 031 816 A discloses a method for cleaning an exhaust gas recirculation line, wherein the exhaust gas recirculation line is disconnected and a cleaning medium is introduced into the exhaust gas recirculation, following gravity and flowing through the exhaust gas recirculation line.
  • the exhaust gas duct is rotated in such a way that the cleaning medium is prevented from penetrating the particle filter.
  • US 6,478,036 B1 describes a method for cleaning an exhaust gas recirculation, whereby a cleaning device is connected by means of a screw connection to a connection on an exhaust manifold, whereby the exhaust gas recirculation cooler, the exhaust gas recirculation valve and the exhaust gas recirculation line are freed of impurities and deposits by introducing a flushing fluid into the exhaust gas recirculation line.
  • the DE 10 2014 001 457 A1 discloses a method for cleaning a heat exchanger in an exhaust gas recirculation system, the heat exchanger being flushed through with a cleaning fluid, the cleaning fluid being mixed with a gas.
  • the object of the invention is to provide a cleaning method for an exhaust gas recirculation system, in which dirt and deposits can be reliably removed from the exhaust gas recirculation and which makes the costly and time-consuming replacement of contaminated components superfluous.
  • the inventive method enables an exhaust gas recirculation line, an exhaust gas recirculation valve and / or an exhaust gas recirculation cooler to be cleaned so that deposits and sooting can be flushed out of the exhaust gas recirculation system without these components having to be replaced.
  • the exhaust gas recirculation channel is closed at least in sections by a diaphragm or a plate, so that the exhaust gas volume guided through the exhaust gas recirculation line is increased.
  • a closure is preferably designed in the manner of a pressure limiting valve in order to avoid damage to the exhaust system and to be able to reduce this pressure in the event of an impermissible pressure increase in the exhaust system.
  • the sooting state of the exhaust gas recirculation line, the exhaust gas recirculation valve and / or the exhaust gas recirculation cooler is determined before an exhaust gas recirculation cleaning is carried out and a method is initiated when the sooting state has reached or exceeded a defined threshold value for sooting. Targeted determination of the initial state enables the exhaust gas recirculation system to be cleaned as required.
  • the flushing fluid is introduced into at least one of the openings while the internal combustion engine is running.
  • a flushing pressure can be built up in a simple manner, which pushes the flushing fluid through the exhaust gas recirculation at high speed and thus enables efficient cleaning of the exhaust gas recirculation line, the exhaust gas recirculation valve and / or the exhaust gas recirculation cooler.
  • the internal combustion engine is operated at a threshold speed during the cleaning process, the threshold speed being above an idling speed of the internal combustion engine.
  • the threshold speed is preferably in the range between 1500 rpm and 4000 rpm, particularly preferably between 2000 rpm and 3000 rpm, for example 2500 rpm.
  • the high exhaust gas flow prevents flushing fluid residues remaining in the exhaust gas recirculation line, the exhaust gas recirculation valve or the exhaust gas recirculation cooler after the cleaning process, which can also have a negative impact on the functioning of the exhaust gas recirculation system.
  • the internal combustion engine is switched off when the flushing agent has been completely emptied into the exhaust gas recirculation line.
  • the internal combustion engine is switched off when the flushing agent has been completely emptied into the exhaust gas recirculation line.
  • the internal combustion engine is switched off after the detergent has been completely emptied, in particular a detergent bottle or a detergent canister, the environmental impact during service can be reduced. It is preferred to switch off the internal combustion engine with a short delay of 1 s to 20 s, in particular from 2 s to 10 s, particularly preferably about 5 s after the flushing agent has been completely emptied, in order to also allow the flushing fluid residue to flow through the To promote exhaust gas recirculation cooler, the exhaust gas recirculation valve and the exhaust gas recirculation line.
  • the rinsing fluid is an aqueous solution of a neutral cleaner with a mixing ratio of 80 to 95 percent by volume of water and 5 to 20 percent by volume of neutral cleaner. With such a Mixing ratio, a particularly good cleaning result could be achieved in experiments with a limited use of flushing fluid.
  • the flushing fluid is introduced into one of the openings at a pressure of 2-5 bar, in particular at a pressure of 3 bar.
  • a flushing fluid that is under increased pressure in relation to the environment can ensure that the flushing fluid is simply introduced into the exhaust gas recirculation line.
  • the pressure is built up in the detergent, in particular in the detergent bottle or the detergent canister, before it is connected to one of the openings on the exhaust gas recirculation line or the exhaust gas duct.
  • the openings are each closed by a sensor, in particular by a temperature sensor or an actuator for an exhaust gas recirculation valve, during normal operation of the internal combustion engine.
  • a sensor in particular by a temperature sensor or an actuator for an exhaust gas recirculation valve
  • the use of openings already present on the exhaust gas recirculation line or the exhaust gas duct means that no additional service openings are necessary for introducing the flushing fluid.
  • the need to dismantle the sensors to uncover the openings can ensure that these sensors are not damaged by the flushing fluid during the cleaning process.
  • an internal combustion engine 10 is shown with an air supply system and an exhaust system.
  • a fresh gas line 16 is connected to an inlet 12 of the internal combustion engine 10.
  • the internal combustion engine 10 is preferably designed as a self-igniting internal combustion engine 10 based on the diesel principle, but can also be designed as an externally ignited internal combustion engine 10 based on the Otto principle.
  • a compressor 18 of an exhaust gas turbocharger 34 and a charge air cooler 20 connected downstream of the compressor 18 in the flow direction are arranged in the fresh gas line 16.
  • the outlet 14 of the internal combustion engine 10 is connected to an exhaust gas duct 40 in which, in the flow direction of an exhaust gas through the exhaust gas duct 40, downstream of the internal combustion engine, a turbine 32 of the exhaust gas turbocharger 34, and downstream of the turbine 32 a catalytic converter 36, in particular an oxidation catalytic converter or a NOx storage catalytic converter, and a particle filter 38, in particular a particle filter with a coating for the selective, catalytic reduction of nitrogen oxides, are arranged downstream of the catalytic converter 36.
  • a catalytic converter 36 in particular an oxidation catalytic converter or a NOx storage catalytic converter
  • a particle filter 38 in particular a particle filter with a coating for the selective, catalytic reduction of nitrogen oxides
  • a first differential pressure line 42 which is connected to a differential pressure sensor 46, branches off from the exhaust gas channel 40 upstream of the particle filter 38. Downstream of the particle filter 38, the exhaust gas duct 40 is connected to the differential pressure sensor 46 via a second differential pressure line 44, so that a pressure difference can be determined via the particle filter 38. This pressure difference can be used to determine the loading state of the particle filter, so that the soot retained in the particle filter 38 can be burned off periodically and the particle filter 38 is released again.
  • an exhaust gas recirculation line 26, 30 branches off from exhaust gas duct 40 and connects this to fresh gas duct 16, downstream of charge air cooler 20 and upstream of inlet 12 of internal combustion engine 10.
  • exhaust gas recirculation line 26, 30 there is an exhaust gas recirculation cooler 28 and an exhaust gas recirculation valve is arranged through which a coolant of the internal combustion engine 10 flows and reduces the exhaust gas temperature of the exhaust gas recirculated via the exhaust gas recirculation line 26, 30.
  • An opening 54 to which a temperature sensor (not shown) can be connected, is provided on the exhaust gas recirculation line 30 downstream of a branch from the exhaust gas duct 40 and upstream of the exhaust gas recirculation cooler 28 and upstream of the exhaust gas recirculation valve.
  • the exhaust gas is cleaned by the catalytic converter 36 and the particle filter 38 and emitted to the environment via the exhaust gas duct 40.
  • a portion of the exhaust gas is fed to the fresh gas duct 16 via the exhaust gas recirculation line 26, 30 and the exhaust gas recirculation cooler 28, so that the combustion temperature in the combustion chambers of the internal combustion engine 10 can be lowered and thus the nitrogen oxide emissions can be reduced .
  • This can lead to sooting of the exhaust gas recirculation cooler 28, the exhaust gas recirculation valve and / or the exhaust gas recirculation line 26, 30 during operation.
  • This sooting leads to the cross-section of the exhaust gas recirculation line 26, 30, the exhaust gas recirculation valve, or the exhaust gas recirculation cooler 28 being reduced and thus only a smaller amount of exhaust gas can be recirculated under otherwise identical operating conditions. This can affect the functioning of the internal combustion engine and lead to an increase in the Emissions. In order to avoid an inadmissible increase in emissions or a malfunction, the components of the exhaust gas recirculation system had to be replaced when a certain sooting state was reached or exceeded.
  • FIG. 2 the internal combustion engine 10 is shown in a service operation for performing a method according to the invention for cleaning the exhaust gas recirculation line 26, 30, the exhaust gas recirculation valve and the exhaust gas recirculation cooler 28.
  • the exhaust gas duct 40 is closed by a closure 48, in particular by a sealing plate.
  • a first section 26 of the exhaust gas recirculation line 26, 30, which opens into the fresh gas line 16 downstream of the charge air cooler 20, is separated from a second section 30 of the exhaust gas recirculation line 26, 30 and the first section 26 is separated by a closure 24, in particular a closure plug or a Sealing plate, closed.
  • a closure 24 in particular a closure plug or a Sealing plate
  • the second section 30 of the exhaust gas recirculation line 26, 30 is, as in FIG Figure 3 shown, connected to a washing container 50. Since the exhaust pipe 40 is closed, the entire exhaust gas flow is guided through the exhaust gas recirculation line 30 and the exhaust gas recirculation cooler 28 in the service mode. In this case, a flushing fluid 58 is fed to the exhaust gas flow through one of the openings 54, 56, which is conveyed by the exhaust gas flow at high speed through the exhaust gas recirculation line 30, the exhaust gas recirculation valve and the exhaust gas recirculation cooler 28. This results in a high cleaning performance.
  • a suction funnel 52 is arranged on the washing container 50, with which the exhaust gas, after the washing fluid has been delivered to the washing container 50, is sucked off and can be drained off accordingly.
  • the method for cleaning the exhaust gas recirculation line 26, 30, the exhaust gas recirculation valve and the exhaust gas recirculation cooler 28 can also be based on FIG Figure 3 to explain.
  • a first method step the sooting state of the exhaust gas recirculation cooler 28, the exhaust gas recirculation valve and the exhaust gas recirculation line 26, 30 is determined. If this sooting state is above a defined threshold value for sooting, the exhaust gas recirculation system 26, 28, 30 must be cleaned.
  • the outlet opening from the exhaust gas channel 40 is first closed or the cross section of the exhaust gas channel is reduced in order to increase an exhaust gas flow through the exhaust gas recirculation line 26, 30.
  • the first section 26 of the exhaust gas recirculation line 26, 30 and the second section 30 of the exhaust gas recirculation line 26, 30 are separated from one another and the first section 26 is closed by a sealing plug.
  • an exhaust gas recirculation valve is connected to the exhaust gas recirculation cooler 28 with a hose.
  • a plug is removed from the exhaust gas recirculation valve and the exhaust gas recirculation valve is locked in an open position.
  • a temperature sensor is removed in the exhaust gas recirculation line 30 upstream of the exhaust gas recirculation cooler 28 and upstream of the exhaust gas recirculation valve, so that the opening 54 is exposed.
  • a rinsing agent in particular a pressure rinsing bottle, is filled with a rinsing fluid based on an aqueous neutral cleaner.
  • the pressure flush bottle is then attached to the opening 54 and an operating pressure of approx. 3 bar is built up in the pressure flush bottle.
  • the internal combustion engine 10 is started and accelerated to a flushing speed of 2000 rpm to 3000 rpm, preferably 2500 rpm, a check being carried out to determine whether the exhaust gas duct 40 is actually essentially gas-tight by the closure 48 is.
  • the flushing fluid is introduced from the pressure flushing bottle into the exhaust gas recirculation line 30, the pressure in the pressure flushing bottle being tracked in order to avoid a pressure drop.
  • the internal combustion engine 10 is switched off after a short run-on phase of 2 s-10 s, preferably about 5 s.
  • another pressure flush bottle can be connected to the exhaust gas recirculation line 30 and another flush cycle can be carried out. If the flushing process of the exhaust gas recirculation line 30 and the exhaust gas recirculation cooler 28 has been successfully completed, the internal combustion engine 10 is reset to the state for normal operation.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust-Gas Circulating Devices (AREA)
  • Exhaust Gas After Treatment (AREA)

Description

Die Erfindung betrifft ein Verfahren zur Reinigung einer Abgasrückführungsleitung gemäß dem Oberbegriff des unabhängigen Patentanspruchs.The invention relates to a method for cleaning an exhaust gas recirculation line according to the preamble of the independent claim.

Die aktuelle und eine zukünftig immer schärfer werdende Abgasgesetzgebung stellen hohe Anforderungen an die motorischen Rohemissionen und die Abgasnachbehandlung von Verbrennungsmotoren. Dabei stellen die Forderungen nach einem weiter sinkenden Verbrauch und die weitere Verschärfung der Abgasnormen hinsichtlich der zulässigen StickoxidEmissionen eine Herausforderung für die Motorenentwickler dar. Bei Ottomotoren erfolgt die Abgasreinigung in bekannter Weise über einen Drei-Wege-Katalysator, sowie dem Drei-Wege-Katalysator vor- und nachgeschaltete weitere Katalysatoren. Bei Dieselmotoren finden aktuell Abgasnachbehandlungssysteme Verwendung, welche einen Oxidationskatalysator oder NOx-Speicherkatalysator, einen Katalysator zur selektiven katalytischen Reduktion von Stickoxiden (SCR-Katalysator) sowie einen Partikelfilter zur Abscheidung von Rußpartikeln und gegebenenfalls weitere Katalysatoren aufweisen. Als Reduktionsmittel wird dabei bevorzugt Ammoniak verwendet. Weil der Umgang mit reinem Ammoniak aufwendig ist, wird bei Fahrzeugen üblicherweise eine synthetische, wässrige Harnstofflösung verwendet, die in einer dem SCR-Katalysator vorgeschalteten Mischeinrichtung mit dem heißen Abgasstrom vermischt wird. Durch diese Vermischung wird die wässrige Harnstofflösung erhitzt, wobei die wässrige Harnstofflösung Ammoniak im Abgaskanal freisetzt. Eine handelsübliche, wässrige Harnstofflösung setzt sind im Allgemeinen aus 32,5 % Harnstoff und 67,5 % Wasser zusammen.The current exhaust gas legislation, and one that will become increasingly strict in the future, place high demands on the engine-related raw emissions and the exhaust gas aftertreatment of internal combustion engines. The demands for a further decrease in consumption and the further tightening of the exhaust gas standards with regard to the permissible nitrogen oxide emissions represent a challenge for the engine developers. In gasoline engines, exhaust gas cleaning is carried out in the known manner using a three-way catalytic converter and a three-way catalytic converter - and further downstream catalysts. Exhaust gas aftertreatment systems are currently used in diesel engines which have an oxidation catalytic converter or NOx storage catalytic converter, a catalytic converter for the selective catalytic reduction of nitrogen oxides (SCR catalytic converter) and a particle filter for separating soot particles and, if necessary, further catalytic converters. Ammonia is preferably used as the reducing agent. Because dealing with pure ammonia is complex, a synthetic, aqueous urea solution is usually used in vehicles, which is mixed with the hot exhaust gas flow in a mixing device upstream of the SCR catalytic converter. As a result of this mixing, the aqueous urea solution is heated, with the aqueous urea solution releasing ammonia in the exhaust gas duct. A commercially available, aqueous urea solution is generally composed of 32.5% urea and 67.5% water.

Eine Möglichkeit die Rohemissionen eines Verbrennungsmotors abzusenken ist die Rückführung von Abgas in den Frischlufttrakt des Verbrennungsmotors. Dadurch kann die Verbrennungstemperatur in den Brennräumen des Verbrennungsmotors abgesenkt und somit insbesondere die Stickoxidbildung vermindert werden. Dabei sind Hochdruck-Abgasrückführungen bekannt, bei denen das Abgas unmittelbar nach einem Auslass des Verbrennungsmotors aus dem Abgaskanal abgeführt und der Ansaugluft unmittelbar vor Eintritt in die Brennräume des Verbrennungsmotors zugeführt wird. Darüber hinaus sind Niederdruck-Abgasrückführungen bekannt, bei denen das Abgas des Verbrennungsmotors stromabwärts einer Turbine des Abgasturboladers und stromabwärts einer Abgasnachbehandlungskomponente, insbesondere eines Partikelfilters, aus dem Abgaskanal abgezapft und dem Luftversorgungssystem stromaufwärts eines Verdichters zugeführt wird. Dabei ist in einer Niederdruck-Abgasrückführung in der Regel ein Abgasrückführungskühler vorgesehen, mit welchem die Abgastemperatur des zurückgeführten Abgases reduziert wird.One way of reducing the raw emissions of an internal combustion engine is to recirculate exhaust gas into the fresh air system of the internal combustion engine. As a result, the combustion temperature in the combustion chambers of the internal combustion engine can be lowered and thus in particular the formation of nitrogen oxide can be reduced. High-pressure exhaust gas recirculation systems are known in which the exhaust gas immediately after an outlet of the Internal combustion engine discharged from the exhaust duct and the intake air is supplied immediately before entering the combustion chamber of the internal combustion engine. In addition, low-pressure exhaust gas recirculation systems are known in which the exhaust gas of the internal combustion engine is tapped from the exhaust gas duct downstream of a turbine of the exhaust gas turbocharger and downstream of an exhaust gas treatment component, in particular a particle filter, and fed to the air supply system upstream of a compressor. In this case, an exhaust gas recirculation cooler is generally provided in a low-pressure exhaust gas recirculation, with which the exhaust gas temperature of the recirculated exhaust gas is reduced.

Im Betrieb des Verbrennungsmotors können sich in der Abgasrückführung Ablagerungen bilden, welche den Leitungsquerschnitt der Abgasrückführungsleitung verringern können und die Funktion eines Abgasrückführungsventils stören können. Dies kann dazu führen, dass einzelne Bauteile der Abgasrückführung ausgetauscht werden müssen, weil die Komponenten ohne eine Demontage nicht gereinigt werden können und die Funktionssicherheit nicht mehr gewährleistet ist.During operation of the internal combustion engine, deposits can form in the exhaust gas recirculation, which can reduce the line cross-section of the exhaust gas recirculation line and disrupt the function of an exhaust gas recirculation valve. This can lead to individual components of the exhaust gas recirculation having to be replaced because the components cannot be cleaned without dismantling and functional reliability is no longer guaranteed.

Aus der EP 1 957 776 B1 ist ein Verfahren zur Reinigung eines Abgasrückführungssystems bei einem Nutzfahrzeug bekannt, bei dem an dem Abgasrückführungssystem eine Frischlufteinspeiseleitung vorgesehen ist, welche aus einem Drucklufttank des Kraftfahrzeuges mit Druckluft versorgt wird. Nachteilig an dieser Lösung ist jedoch, dass sie sich nicht auf PKW übertragen lassen, da PKW in der Regel über keinen eigenen Drucklufttank oder ein Druckluftsystem verfügen.From the EP 1 957 776 B1 A method for cleaning an exhaust gas recirculation system in a commercial vehicle is known, in which a fresh air feed line is provided on the exhaust gas recirculation system, which is supplied with compressed air from a compressed air tank of the motor vehicle. The disadvantage of this solution, however, is that it cannot be transferred to cars, since cars usually do not have their own compressed air tank or a compressed air system.

Die FR 2 885 178 A1 offenbart einen Verbrennungsmotor mit einer Abgasanlage und einem Ansaugtrakt, wobei die Abgasanlage über eine Abgasrückführung mit dem Ansaugtrakt verbunden ist. Um die Abgasrückführung zu reinigen, wird eine Abgasklappe geschlossen und ein Reinigungsfluid in den Abgaskanal eingebracht, um die Abgasrückführungsleitung zu spülen.The FR 2 885 178 A1 discloses an internal combustion engine with an exhaust system and an intake system, the exhaust system being connected to the intake system via an exhaust gas recirculation system. In order to clean the exhaust gas recirculation, an exhaust flap is closed and a cleaning fluid is introduced into the exhaust gas duct in order to flush the exhaust gas recirculation line.

JP 2017 031 816 A offenbart ein Verfahren zur Reinigung einer Abgasrückführungsleitung, wobei die Abgasrückführungsleitung getrennt wird und ein Reinigungsmedium in die Abgasrückführung eingeleitet, der Schwerkraft folgend, durch die Abgasrückführungsleitung fließt. Dabei wird der Abgaskanal so gedreht, dass ein Eindringen des Reinigungsmediums in den Partikelfilter verhindert wird. JP 2017 031 816 A discloses a method for cleaning an exhaust gas recirculation line, wherein the exhaust gas recirculation line is disconnected and a cleaning medium is introduced into the exhaust gas recirculation, following gravity and flowing through the exhaust gas recirculation line. The exhaust gas duct is rotated in such a way that the cleaning medium is prevented from penetrating the particle filter.

Aus der US 2014 / 331 954 A1 ist ein Reinigungssystem für eine Abgasanlage eines Verbrennungsmotors bekannt, wobei ein wasserbasiertes Reinigungsfluid in die Abgasanlage eingeleitet wird.From the US 2014/331 954 A1 A cleaning system for an exhaust system of an internal combustion engine is known, a water-based cleaning fluid being introduced into the exhaust system.

US 6 478 036 B1 beschreibt ein Verfahren zur Reinigung einer Abgasrückführung, wobei eine Reinigungsvorrichtung mittels einer Schraubverbindung an einen Anschluss an einem Abgaskrümmer angeschlossen wird, wobei durch das Einbringen eines Spülfluids in die Abgasrückführungsleitung der Abgasrückführungskühler, das Abgasrückführungsventil und die Abgasrückführungsleitung von Verunreinigungen und Ablagerungen befreit werden. US 6,478,036 B1 describes a method for cleaning an exhaust gas recirculation, whereby a cleaning device is connected by means of a screw connection to a connection on an exhaust manifold, whereby the exhaust gas recirculation cooler, the exhaust gas recirculation valve and the exhaust gas recirculation line are freed of impurities and deposits by introducing a flushing fluid into the exhaust gas recirculation line.

Aus der DE 10 2015 119 204 A1 ist ein Verfahren bekannt, bei welchem Wasser in die Brennräume des Verbrennungsmotors eingespritzt wird, um die Verbrennungstemperatur zusätzlich zur Temperatur durch eine Abgasrückführung zu reduzieren.From the DE 10 2015 119 204 A1 a method is known in which water is injected into the combustion chambers of the internal combustion engine in order to reduce the combustion temperature in addition to the temperature by means of exhaust gas recirculation.

Die DE 10 2014 001 457 A1 offenbart ein Verfahren zur Reinigung eines Wärmetauschers in einer Abgasrückführung, wobei der Wärmetauscher mit einer Reinigungsflüssigkeit durchgespült wird, wobei die Reinigungsflüssigkeit mit einem Gas versetzt wird.The DE 10 2014 001 457 A1 discloses a method for cleaning a heat exchanger in an exhaust gas recirculation system, the heat exchanger being flushed through with a cleaning fluid, the cleaning fluid being mixed with a gas.

Aufgabe der Erfindung ist es, ein Reinigungsverfahren für ein Abgasrückführungssystem bereitzustellen, bei dem Verschmutzungen und Ablagerungen aus der Abgasrückführung zuverlässig entfernt werden können und welches einen kosten- und zeitintensiven Austausch von verschmutzten Komponenten überflüssig macht.The object of the invention is to provide a cleaning method for an exhaust gas recirculation system, in which dirt and deposits can be reliably removed from the exhaust gas recirculation and which makes the costly and time-consuming replacement of contaminated components superfluous.

Erfindungsgemäß wird die Aufgabe durch ein Verfahren zur Reinigung einer Abgasrückführungsleitung und/oder eines Abgasrückführungskühlers an einem Verbrennungsmotor gelöst, welches folgende Schritte umfasst:

  • Drosseln eines Abgasstroms durch den Abgaskanal oder Verschließen des Abgaskanals durch einen Verschluss, sodass das durch den Abgasrückführungskanal geleitete Abgasvolumen erhöht wird,
  • Trennen der ersten Abgasrückführungsleitung von der zweiten Abgasrückführungsleitung,
  • Verschließen des offenen Endes der ersten Abgasrückführungsleitung durch einen weiteren Verschluss, sodass ein Eintrag in das Luftversorgungssystem des Verbrennungsmotors unterbunden wird,
  • Verbinden des offenen Endes der zweiten Abgasrückführungsleitung mit einem Spülbehälter,
  • Anschluss eines Spülmittels an eine Öffnung an der Abgasrückführungsleitung oder dem Abgaskanal in Spülrichtung stromaufwärts eines Abgasrückführungskühlers und stromaufwärts eines Abgasrückführungsventils der Abgasrückführungsleitung,
  • Einbringen eines Spülfluids in die Abgasrückführungsleitung, wobei der Abgasrückführungskühler, das Abgasrückführungsventil und die Abgasrückführungsleitung von Verunreinigungen und Ablagerungen befreit werden.
According to the invention, the object is achieved by a method for cleaning an exhaust gas recirculation line and / or an exhaust gas recirculation cooler on an internal combustion engine, which comprises the following steps:
  • Throttling an exhaust gas flow through the exhaust gas duct or closing the exhaust gas duct with a closure so that the exhaust gas volume conducted through the exhaust gas recirculation duct is increased,
  • Separating the first exhaust gas recirculation line from the second exhaust gas recirculation line,
  • Closing the open end of the first exhaust gas recirculation line by a further closure, so that entry into the air supply system of the internal combustion engine is prevented,
  • Connecting the open end of the second exhaust gas recirculation line to a flushing container,
  • Connection of a flushing agent to an opening on the exhaust gas recirculation line or the exhaust gas duct in the flushing direction upstream of an exhaust gas recirculation cooler and upstream of an exhaust gas recirculation valve of the exhaust gas recirculation line,
  • Introducing a flushing fluid into the exhaust gas recirculation line, the exhaust gas recirculation cooler, the exhaust gas recirculation valve and the exhaust gas recirculation line being freed of impurities and deposits.

Durch das erfindungsgemäße Verfahren ist die Reinigung einer Abgasrückführungsleitung, eines Abgasrückführungsventils und/oder eines Abgasrückführungskühlers möglich, sodass Ablagerungen und Versottungen aus dem Abgasrückführungssystem herausgespült werden können, ohne dass diese Bauteile ausgetauscht werden müssen. Dadurch ist ein einfacher Service möglich, wodurch in der Wartung und Instandhaltung des Kraftfahrzeuges Zeit und Geld eingespart werden können. Dabei wird der Abgasrückführungskanal durch eine Blende oder eine Platte zumindest abschnittsweise verschlossen, sodass das durch die Abgasrückführungsleitung geführte Abgasvolumen vergrößert wird. Bevorzugt ist ein Verschluss nach Art eines Druckbegrenzungsventils ausgeführt, um eine Beschädigung der Abgasanlage zu vermeiden und bei einem unzulässigen Druckanstieg in der Abgasanlage diesen Druck abbauen zu können.The inventive method enables an exhaust gas recirculation line, an exhaust gas recirculation valve and / or an exhaust gas recirculation cooler to be cleaned so that deposits and sooting can be flushed out of the exhaust gas recirculation system without these components having to be replaced. This enables simple servicing, which saves time and money in the maintenance and repair of the motor vehicle. In this case, the exhaust gas recirculation channel is closed at least in sections by a diaphragm or a plate, so that the exhaust gas volume guided through the exhaust gas recirculation line is increased. A closure is preferably designed in the manner of a pressure limiting valve in order to avoid damage to the exhaust system and to be able to reduce this pressure in the event of an impermissible pressure increase in the exhaust system.

Durch die in den abhängigen Ansprüchen aufgeführten Merkmale sind vorteilhafte Verbesserungen und Weiterentwicklungen des im unabhängigen Anspruch angegebenen Verfahrens zur Reinigung einer Abgasrückführungsleitung oder eines Abgasrückführungskühlers möglich.The features listed in the dependent claims enable advantageous improvements and further developments of the method specified in the independent claim for cleaning an exhaust gas recirculation line or an exhaust gas recirculation cooler.

In einer bevorzugten Ausführungsform der Erfindung ist vorgesehen, dass vor dem Durchführen einer Abgasrückführungsreinigung der Versottungszustand der Abgasrückführungsleitung, des Abgasrückführungsventils und/oder des Abgasrückführungskühlers ermittelt wird und ein Verfahren eingeleitet wird, wenn der Versottungszustand einen definierten Schwellenwert für die Versottung erreicht oder überschritten hat. Durch eine gezielte Ermittlung des Ausgangszustands kann eine bedarfsgerechte Reinigung des Abgasrückführungssystems erfolgen. Dabei müssen keine festen Serviceintervalle eingehalten werden, sondern es kann in Abhängigkeit von einer real auftretenden Verschmutzung oder Versottung entschieden werden, ob ein definierter Schwellenwert für die Versottung erreicht ist und dementsprechend eine Reinigung der Abgasrückführungsleitung, des Abgasrückführungsventils und/oder des Abgasrückführungskühlers notwendig ist.In a preferred embodiment of the invention it is provided that the sooting state of the exhaust gas recirculation line, the exhaust gas recirculation valve and / or the exhaust gas recirculation cooler is determined before an exhaust gas recirculation cleaning is carried out and a method is initiated when the sooting state has reached or exceeded a defined threshold value for sooting. Targeted determination of the initial state enables the exhaust gas recirculation system to be cleaned as required. No fixed service intervals have to be adhered to, but can be done in Depending on actual contamination or sooting, a decision is made as to whether a defined threshold value for sooting has been reached and accordingly cleaning of the exhaust gas recirculation line, the exhaust gas recirculation valve and / or the exhaust gas recirculation cooler is necessary.

Bevorzugt ist dabei, wenn das Spülfluid bei laufendem Verbrennungsmotor in zumindest eine der Öffnungen eingebracht wird. Durch einen laufenden Motorbetrieb kann auf einfache Art und Weise ein Spüldruck aufgebaut werden, welcher das Spülfluid mit hoher Geschwindigkeit durch die Abgasrückführung drückt und somit eine effiziente Reinigung der Abgasrückführungsleitung, des Abgasrückführungsventils und/oder des Abgasrückführungskühlers ermöglicht.It is preferred here if the flushing fluid is introduced into at least one of the openings while the internal combustion engine is running. With the engine running, a flushing pressure can be built up in a simple manner, which pushes the flushing fluid through the exhaust gas recirculation at high speed and thus enables efficient cleaning of the exhaust gas recirculation line, the exhaust gas recirculation valve and / or the exhaust gas recirculation cooler.

Besonders bevorzugt ist dabei, wenn der Verbrennungsmotor während des Reinigungsvorgangs mit einer Schwellendrehzahl betrieben wird, wobei die Schwellendrehzahl oberhalb einer Leerlaufdrehzahl des Verbrennungsmotors liegt. Durch eine höhere Drehzahl kann der Volumenstrom an Abgas durch die Abgasrückführungsleitung und den Abgasrückführungskühler erhöht werden. Dabei liegt die Schwellendrehzahl vorzugsweise im Bereich zwischen 1500 U/min und 4000 U/min, besonders bevorzugt zwischen 2000 U/min und 3000 U/min, beispielsweise 2500 U/min. Durch den hohen Abgasstrom wird verhindert, dass nach dem Reinigungsverfahren Spülfluidreste in der Abgasrückführungsleitung, dem Abgasrückführungsventil oder dem Abgasrückführungskühler zurückbleiben, welche ebenfalls negativen Einfluss auf die Funktion des Abgasrückführungssystems haben können.It is particularly preferred if the internal combustion engine is operated at a threshold speed during the cleaning process, the threshold speed being above an idling speed of the internal combustion engine. With a higher speed, the volume flow of exhaust gas through the exhaust gas recirculation line and the exhaust gas recirculation cooler can be increased. The threshold speed is preferably in the range between 1500 rpm and 4000 rpm, particularly preferably between 2000 rpm and 3000 rpm, for example 2500 rpm. The high exhaust gas flow prevents flushing fluid residues remaining in the exhaust gas recirculation line, the exhaust gas recirculation valve or the exhaust gas recirculation cooler after the cleaning process, which can also have a negative impact on the functioning of the exhaust gas recirculation system.

In einer weiteren Verbesserung des Verfahrens ist vorgesehen, dass der Verbrennungsmotor abgeschaltet wird, wenn das Spülmittel vollständig in die Abgasrückführungsleitung entleert wurde. Durch ein Abschalten des Verbrennungsmotors nach dem vollständigen Entleeren des Spülmittels, insbesondere einer Spülmittelflasche oder eines Spülmittelkanisters kann die Umweltbelastung beim Service reduziert werden. Dabei ist eine Abschaltung des Verbrennungsmotors mit einer kurzen Verzögerung von 1 s bis 20 s, insbesondere von 2 s bis 10 s, besonders bevorzugt von etwa 5 s nach dem vollständigen Entleeren des Spülmittels bevorzugt, um auch den Spülfluidrest noch mit einem entsprechenden Gasstrom durch den Abgasrückführungskühler, das Abgasrückführungsventil und die Abgasrückführungsleitung zu fördern.In a further improvement of the method it is provided that the internal combustion engine is switched off when the flushing agent has been completely emptied into the exhaust gas recirculation line. By switching off the internal combustion engine after the detergent has been completely emptied, in particular a detergent bottle or a detergent canister, the environmental impact during service can be reduced. It is preferred to switch off the internal combustion engine with a short delay of 1 s to 20 s, in particular from 2 s to 10 s, particularly preferably about 5 s after the flushing agent has been completely emptied, in order to also allow the flushing fluid residue to flow through the To promote exhaust gas recirculation cooler, the exhaust gas recirculation valve and the exhaust gas recirculation line.

In einer bevorzugten Ausführungsform des Verfahrens ist vorgesehen, dass das Spülfluid eine wässrige Lösung eines Neutralreinigers mit einem Mischungsverhältnis von 80 bis 95 Volumenprozent Wasser und 5 bis 20 Volumenprozent Neutralreiniger ist. Bei einem solchen Mischungsverhältnis konnte in Experimenten ein besonders gutes Reinigungsergebnis bei einem begrenzten Spülfluideinsatz erreicht werden.In a preferred embodiment of the method it is provided that the rinsing fluid is an aqueous solution of a neutral cleaner with a mixing ratio of 80 to 95 percent by volume of water and 5 to 20 percent by volume of neutral cleaner. With such a Mixing ratio, a particularly good cleaning result could be achieved in experiments with a limited use of flushing fluid.

Gemäß einer bevorzugten Ausführungsform der Erfindung ist vorgesehen, dass das Spülfluid mit einem Druck von 2 - 5 bar, insbesondere mit einem Druck von 3 bar, in eine der Öffnungen eingebracht wird. Durch ein unter einem gegenüber der Umgebung unter erhöhtem Druck stehenden Spülfluid kann ein einfaches Einbringen des Spülfluids in die Abgasrückführungsleitung gewährleistet werden. Dabei wird der Druck in dem Spülmittel, insbesondere in der Spülmittelflasche oder dem Spülmittelkanister aufgebaut, bevor dieser an eine der Öffnungen an der Abgasrückführungsleitung oder dem Abgaskanal angeschlossen wird.According to a preferred embodiment of the invention it is provided that the flushing fluid is introduced into one of the openings at a pressure of 2-5 bar, in particular at a pressure of 3 bar. A flushing fluid that is under increased pressure in relation to the environment can ensure that the flushing fluid is simply introduced into the exhaust gas recirculation line. The pressure is built up in the detergent, in particular in the detergent bottle or the detergent canister, before it is connected to one of the openings on the exhaust gas recirculation line or the exhaust gas duct.

In einer vorteilhaften Ausführungsform der Erfindung ist vorgesehen, dass die Öffnungen im Normalbetrieb des Verbrennungsmotors jeweils durch einen Sensor, insbesondere durch einen Temperatursensor oder einen Aktuator für ein Abgasrückführungsventil verschlossen sind. Durch die Verwendung von bereits an der Abgasrückführungsleitung oder dem Abgaskanal vorhandenen Öffnungen sind keine zusätzlichen Serviceöffnungen für das Einbringen von dem Spülfluid notwendig. Zudem kann durch die zur Offenlegung der Öffnungen notwendige Demontage der Sensoren sichergestellt werden, dass diese Sensoren durch das Spülfluid während des Reinigungsverfahrens nicht beschädigt werden.In an advantageous embodiment of the invention it is provided that the openings are each closed by a sensor, in particular by a temperature sensor or an actuator for an exhaust gas recirculation valve, during normal operation of the internal combustion engine. The use of openings already present on the exhaust gas recirculation line or the exhaust gas duct means that no additional service openings are necessary for introducing the flushing fluid. In addition, the need to dismantle the sensors to uncover the openings can ensure that these sensors are not damaged by the flushing fluid during the cleaning process.

In einer weiteren Verbesserung des Verfahrens ist vorgesehen, dass nach einem Spülvorgang die Restversottung der Abgasrückführungsleitung, des Abgasrückführungsventils und/oder des Abgasrückführungskühlers gemessen wird und das Verfahren solange wiederholt wird, bis die Restversottung unter einem zulässigen Schwellenwert liegt. Durch eine Überprüfung des Reinigungserfolgs kann eine bedarfsgerechte Einbringung von Spülfluid erfolgen, sodass die Menge an Spülfluid entsprechend erhöht oder reduziert werden kann. Dies führt zu einer Verringerung des Spülfluideinsatzes, da nicht immer der Einsatz einer maximalen Spülmittelmenge notwendig ist.In a further improvement of the method it is provided that after a flushing process the residual sooting of the exhaust gas recirculation line, the exhaust gas recirculation valve and / or the exhaust gas recirculation cooler is measured and the method is repeated until the residual sooting is below a permissible threshold value. By checking the cleaning success, flushing fluid can be introduced as required, so that the amount of flushing fluid can be increased or reduced accordingly. This leads to a reduction in the use of flushing fluid, since it is not always necessary to use a maximum amount of flushing agent.

Die verschiedenen in dieser Anmeldung genannten Ausführungsformen der Erfindung sind, sofern im Einzelfall nicht anders ausgeführt, mit Vorteil miteinander kombinierbar.The various embodiments of the invention mentioned in this application can be advantageously combined with one another, unless stated otherwise in the individual case.

Die Erfindung wird nachfolgend in Ausführungsbeispielen anhand der zugehörigen Zeichnungen erläutert. Gleiche Bauteile oder Bauteile mit gleicher Funktion sind dabei mit den gleichen Bezugszeichen gekennzeichnet. Es zeigen:

Figur 1
einen Verbrennungsmotor mit einem Frischluftsystem und einer Abgasanlage, wobei die Abgasanlage über eine Abgasrückführleitung mit dem Frischluftsystem verbunden ist;
Figur 2
den Verbrennungsmotor, wobei zur Reinigung des Abgasrückführungssystems die Einleitung von Abgas in das Frischluftsystem unterbunden ist und der Abgaskanal durch einen Verschluss verschlossen ist; und
Figur 3
den Verbrennungsmotor, wobei an dem Verbrennungsmotor ein erfindungsgemäßes Verfahren zur Reinigung einer Abgasrückführungsleitung und/oder eines Abgasrückführungskühlers durchgeführt wird.
The invention is explained below in exemplary embodiments with reference to the accompanying drawings. The same components or components with the same function are identified with the same reference symbols. Show it:
Figure 1
an internal combustion engine with a fresh air system and an exhaust system, the exhaust system being connected to the fresh air system via an exhaust gas recirculation line;
Figure 2
the internal combustion engine, the introduction of exhaust gas into the fresh air system being prevented for cleaning the exhaust gas recirculation system and the exhaust gas duct being closed by a closure; and
Figure 3
the internal combustion engine, a method according to the invention for cleaning an exhaust gas recirculation line and / or an exhaust gas recirculation cooler being carried out on the internal combustion engine.

In Figur 1 ist ein Verbrennungsmotor 10 mit einem Luftversorgungssystem und einer Abgasanlage dargestellt. Dazu ist eine Frischgasleitung 16 mit einem Einlass 12 des Verbrennungsmotors 10 verbunden. Der Verbrennungsmotor 10 ist vorzugsweise als selbstzündender Verbrennungsmotor 10 nach dem Dieselprinzip ausgebildet, kann aber auch als fremdgezündeter Verbrennungsmotor 10 nach dem Ottoprinzip ausgebildet sein. In der Frischgasleitung 16 sind ein Verdichter 18 eines Abgasturboladers 34 sowie in Strömungsrichtung dem Verdichter 18 nachgeschaltet ein Ladeluftkühler 20 angeordnet. Der Auslass 14 des Verbrennungsmotors 10 ist mit einem Abgaskanal 40 verbunden, in welchem in Strömungsrichtung eines Abgases durch den Abgaskanal 40 stromabwärts des Verbrennungsmotors eine Turbine 32 des Abgasturboladers 34, stromabwärts der Turbine 32 ein Katalysator 36, insbesondere ein Oxidationskatalysator oder ein NOx-Speicherkatalysator, und stromabwärts des Katalysators 36 ein Partikelfilter 38, insbesondere ein Partikelfilter mit einer Beschichtung zur selektiven, katalytischen Reduktion von Stickoxiden, angeordnet sind.In Figure 1 an internal combustion engine 10 is shown with an air supply system and an exhaust system. For this purpose, a fresh gas line 16 is connected to an inlet 12 of the internal combustion engine 10. The internal combustion engine 10 is preferably designed as a self-igniting internal combustion engine 10 based on the diesel principle, but can also be designed as an externally ignited internal combustion engine 10 based on the Otto principle. A compressor 18 of an exhaust gas turbocharger 34 and a charge air cooler 20 connected downstream of the compressor 18 in the flow direction are arranged in the fresh gas line 16. The outlet 14 of the internal combustion engine 10 is connected to an exhaust gas duct 40 in which, in the flow direction of an exhaust gas through the exhaust gas duct 40, downstream of the internal combustion engine, a turbine 32 of the exhaust gas turbocharger 34, and downstream of the turbine 32 a catalytic converter 36, in particular an oxidation catalytic converter or a NOx storage catalytic converter, and a particle filter 38, in particular a particle filter with a coating for the selective, catalytic reduction of nitrogen oxides, are arranged downstream of the catalytic converter 36.

Stromaufwärts des Partikelfilters 38 zweigt eine erste Differenzdruckleitung 42 aus dem Abgaskanal 40 ab, welche mit einem Differenzdrucksensor 46 verbunden ist. Stromabwärts des Partikelfilters 38 ist der Abgaskanal 40 über eine zweite Differenzdruckleitung 44 mit dem Differenzdrucksensor 46 verbunden, sodass eine Druckdifferenz über den Partikelfilter 38 ermittelt werden kann. Diese Druckdifferenz kann zur Ermittlung des Beladungszustandes des Partikelfilters genutzt werden, sodass der im Partikelfilter 38 zurückgehaltene Ruß periodisch abgebrannt werden kann und den Partikelfilter 38 wieder freisetzt.A first differential pressure line 42, which is connected to a differential pressure sensor 46, branches off from the exhaust gas channel 40 upstream of the particle filter 38. Downstream of the particle filter 38, the exhaust gas duct 40 is connected to the differential pressure sensor 46 via a second differential pressure line 44, so that a pressure difference can be determined via the particle filter 38. This pressure difference can be used to determine the loading state of the particle filter, so that the soot retained in the particle filter 38 can be burned off periodically and the particle filter 38 is released again.

Stromabwärts des Auslasses 14 und stromaufwärts der Turbine 32 zweigt eine Abgasrückführungsleitung 26, 30 aus dem Abgaskanal 40 ab und verbindet diesen mit dem Frischgaskanal 16 stromabwärts des Ladeluftkühlers 20 und stromaufwärts des Einlasses 12 des Verbrennungsmotors 10. In der Abgasrückführungsleitung 26, 30 sind ein Abgasrückführungskühler 28 und ein Abgasrückführungsventil angeordnet, welcher von einem Kühlmittel des Verbrennungsmotors 10 durchströmt wird und die Abgastemperatur des über die Abgasrückführungsleitung 26, 30 zurückgeführten Abgases reduziert. An der Abgasrückführungsleitung 30 ist stromabwärts einer Verzweigung von dem Abgaskanal 40 und stromaufwärts des Abgasrückführungskühlers 28 und stromaufwärts des Abgasrückführungsventils eine Öffnung 54 vorgesehen, an welche ein nicht dargestellter Temperatursensor angeschlossen werden kann. An dem Abgaskanal 40 ist stromabwärts des Auslasses 14 und stromaufwärts der Turbine 32 des Abgasturboladers 34 eine weitere Öffnung 56 zum Anschluss eines Sensors, insbesondere eines Abgassensors oder eines Temperatursensors vorgesehen.Downstream of outlet 14 and upstream of turbine 32, an exhaust gas recirculation line 26, 30 branches off from exhaust gas duct 40 and connects this to fresh gas duct 16, downstream of charge air cooler 20 and upstream of inlet 12 of internal combustion engine 10. In exhaust gas recirculation line 26, 30 there is an exhaust gas recirculation cooler 28 and an exhaust gas recirculation valve is arranged through which a coolant of the internal combustion engine 10 flows and reduces the exhaust gas temperature of the exhaust gas recirculated via the exhaust gas recirculation line 26, 30. An opening 54, to which a temperature sensor (not shown) can be connected, is provided on the exhaust gas recirculation line 30 downstream of a branch from the exhaust gas duct 40 and upstream of the exhaust gas recirculation cooler 28 and upstream of the exhaust gas recirculation valve. A further opening 56 for connecting a sensor, in particular an exhaust gas sensor or a temperature sensor, is provided on the exhaust gas duct 40 downstream of the outlet 14 and upstream of the turbine 32 of the exhaust gas turbocharger 34.

In dem in Figur 1 dargestellten Normalbetrieb des Verbrennungsmotors 10 wird das Abgas durch den Katalysator 36 und den Partikelfilter 38 gereinigt über den Abgaskanal 40 an die Umwelt emittiert. Um die Emissionen des Verbrennungsmotors 10 zu reduzieren, wird zumindest in bestimmten Betriebspunkten eine Teilmenge des Abgases über die Abgasrückführungsleitung 26, 30 und den Abgasrückführungskühler 28 dem Frischgaskanal 16 zugeführt, sodass die Verbrennungstemperatur in den Brennräumen des Verbrennungsmotors 10 gesenkt und somit die Stickoxidemissionen reduziert werden können. Dabei kann es im Betrieb zu einer Versottung des Abgasrückführungskühlers 28, des Abgasrückführungsventils und/oder der Abgasrückführungsleitung 26, 30 kommen. Diese Versottung führt dazu, dass sich der Querschnitt der Abgasrückführungsleitung 26, 30, des Abgasrückführungsventils, beziehungsweise des Abgasrückführungskühlers 28 verringert und somit bei ansonsten gleichen Betriebsbedingungen nur noch eine geringere Menge an Abgas zurückgeführt werden kann. Dies kann die Funktion des Verbrennungsmotors beeinflussen und zu einer Erhöhung der Emissionen führen. Um eine unzulässige Erhöhung der Emissionen oder eine Funktionsstörung zu vermeiden, mussten bislang die Komponenten des Abgasrückführungssystems ausgetauscht werden, wenn ein bestimmter Versottungszustand erreicht oder überschritten wurde.In the in Figure 1 Normal operation of the internal combustion engine 10 shown, the exhaust gas is cleaned by the catalytic converter 36 and the particle filter 38 and emitted to the environment via the exhaust gas duct 40. In order to reduce the emissions of the internal combustion engine 10, at least at certain operating points, a portion of the exhaust gas is fed to the fresh gas duct 16 via the exhaust gas recirculation line 26, 30 and the exhaust gas recirculation cooler 28, so that the combustion temperature in the combustion chambers of the internal combustion engine 10 can be lowered and thus the nitrogen oxide emissions can be reduced . This can lead to sooting of the exhaust gas recirculation cooler 28, the exhaust gas recirculation valve and / or the exhaust gas recirculation line 26, 30 during operation. This sooting leads to the cross-section of the exhaust gas recirculation line 26, 30, the exhaust gas recirculation valve, or the exhaust gas recirculation cooler 28 being reduced and thus only a smaller amount of exhaust gas can be recirculated under otherwise identical operating conditions. This can affect the functioning of the internal combustion engine and lead to an increase in the Emissions. In order to avoid an inadmissible increase in emissions or a malfunction, the components of the exhaust gas recirculation system had to be replaced when a certain sooting state was reached or exceeded.

In Figur 2 ist ein der Verbrennungsmotor 10 in einem Servicebetrieb zur Durchführung eines erfindungsgemäßen Verfahrens zur Reinigung der Abgasrückführungsleitung 26, 30, des Abgasrückführungsventils und des Abgasrückführungskühlers 28 dargestellt. Dazu wird der Abgaskanal 40 durch einen Verschluss 48, insbesondere durch eine Dichtplatte, verschlossen. Ferner wird ein erster Abschnitt 26 der Abgasrückführungsleitung 26, 30, welcher stromabwärts des Ladeluftkühlers 20 in die Frischgasleitung 16 mündet, von einem zweiten Abschnitt 30 der Abgasrückführungsleitung 26, 30 getrennt und der erste Abschnitt 26 durch einen Verschluss 24, insbesondere durch einen Verschlussstopfen oder eine Dichtplatte, verschlossen. Somit können während des Reinigungsverfahrens kein Abgas und keine sonstigen Verschmutzungen in die Frischgasleitung 16 eindringen. Der zweite Abschnitt 30 der Abgasrückführungsleitung 26, 30 wird, wie in Figur 3 dargestellt, mit einem Spülbehälter 50 verbunden. Da die Abgasleitung 40 verschlossen ist, wird in dem Servicebetrieb der komplette Abgasstrom durch die Abgasrückführungsleitung 30 und den Abgasrückführungskühler 28 geführt. Dabei wird dem Abgasstrom durch eine der Öffnungen 54, 56 ein Spülfluid 58 zugeführt, welches von dem Abgasstrom mit hoher Geschwindigkeit durch die Abgasrückführungsleitung 30, das Abgasrückführungsventil und den Abgasrückführungskühler 28 gefördert wird. Dadurch wird eine hohe Reinigungsleistung erzielt. An dem Spülbehälter 50 ist ein Absaugtrichter 52 angeordnet, mit welchem das Abgas, nachdem das Spülfluid an den Spülbehälter 50 abgegeben wurde, abgesaugt wird und entsprechend abgeleitet werden kann.In Figure 2 the internal combustion engine 10 is shown in a service operation for performing a method according to the invention for cleaning the exhaust gas recirculation line 26, 30, the exhaust gas recirculation valve and the exhaust gas recirculation cooler 28. For this purpose, the exhaust gas duct 40 is closed by a closure 48, in particular by a sealing plate. Furthermore, a first section 26 of the exhaust gas recirculation line 26, 30, which opens into the fresh gas line 16 downstream of the charge air cooler 20, is separated from a second section 30 of the exhaust gas recirculation line 26, 30 and the first section 26 is separated by a closure 24, in particular a closure plug or a Sealing plate, closed. Thus, no exhaust gas and no other contaminants can penetrate into the fresh gas line 16 during the cleaning process. The second section 30 of the exhaust gas recirculation line 26, 30 is, as in FIG Figure 3 shown, connected to a washing container 50. Since the exhaust pipe 40 is closed, the entire exhaust gas flow is guided through the exhaust gas recirculation line 30 and the exhaust gas recirculation cooler 28 in the service mode. In this case, a flushing fluid 58 is fed to the exhaust gas flow through one of the openings 54, 56, which is conveyed by the exhaust gas flow at high speed through the exhaust gas recirculation line 30, the exhaust gas recirculation valve and the exhaust gas recirculation cooler 28. This results in a high cleaning performance. A suction funnel 52 is arranged on the washing container 50, with which the exhaust gas, after the washing fluid has been delivered to the washing container 50, is sucked off and can be drained off accordingly.

Das Verfahren zur Reinigung der Abgasrückführungsleitung 26, 30, des Abgasrückführungsventils sowie des Abgasrückführungskühlers 28 lässt sich ebenfalls anhand von Figur 3 erklären. In einem ersten Verfahrensschritt wird der Versottungszustand des Abgasrückführungskühlers 28, des Abgasrückführungsventils und der Abgasrückführungsleitung 26, 30 ermittelt. Liegt dieser Versottungszustand oberhalb eines definierten Schwellenwertes für die Versottung, so ist eine Reinigung des Abgasrückführungssystems 26, 28, 30 notwendig. Dazu wird in einem zweiten Verfahrensschritt zunächst die Austrittöffnung aus dem Abgaskanal 40 verschlossen oder der Querschnitt des Abgaskanals reduziert, um einen Abgasstrom durch die Abgasrückführungsleitung 26, 30 zu erhöhen. Dies erfolgt vorzugsweise durch eine Platte nach dem Prinzip eines Druckbegrenzungsventils, sodass eine Beschädigung der Abgasnachbehandlungskomponenten aufgrund eines unzulässigen Druckaufbaus in der Abgasanlage vermieden wird. Ferner werden in einem dritten Verfahrensschritt der erste Abschnitt 26 der Abgasrückführungsleitung 26, 30 und der zweite Abschnitt 30 der Abgasrückführungsleitung 26, 30 voneinander getrennt und der erste Abschnitt 26 durch einen Verschlussstopfen verschlossen. In einem weiteren Verfahrensschritt wird ein Abgasrückführungsventil mit einem Schlauch an den Abgasrückführungskühler 28 angebunden. In einem nächsten Verfahrensschritt wird ein Stecker an dem Abgasrückführungsventil abgezogen und das Abgasrückführungsventil in einer geöffneten Stellung festgesetzt. In einem nächsten Verfahrensschritt wird ein Temperatursensor in der Abgasrückführungsleitung 30 stromaufwärts des Abgasrückführungskühlers 28 und stromaufwärts des Abgasrückführungsventils ausgebaut, sodass die Öffnung 54 freigelegt wird. Parallel wird ein Spülmittel, insbesondere eine Druckspülflasche mit einem Spülfluid auf Basis eines wässrigen Neutralreinigers, befüllt. Anschließend wird die Druckspülflasche an der Öffnung 54 befestigt und ein Betriebsdruck von ca. 3 bar in der Druckspülflasche aufgebaut.The method for cleaning the exhaust gas recirculation line 26, 30, the exhaust gas recirculation valve and the exhaust gas recirculation cooler 28 can also be based on FIG Figure 3 to explain. In a first method step, the sooting state of the exhaust gas recirculation cooler 28, the exhaust gas recirculation valve and the exhaust gas recirculation line 26, 30 is determined. If this sooting state is above a defined threshold value for sooting, the exhaust gas recirculation system 26, 28, 30 must be cleaned. For this purpose, in a second method step, the outlet opening from the exhaust gas channel 40 is first closed or the cross section of the exhaust gas channel is reduced in order to increase an exhaust gas flow through the exhaust gas recirculation line 26, 30. This is preferably done by a plate on the principle of a pressure relief valve, so that damage to the Exhaust aftertreatment components due to an impermissible pressure build-up in the exhaust system is avoided. Furthermore, in a third method step, the first section 26 of the exhaust gas recirculation line 26, 30 and the second section 30 of the exhaust gas recirculation line 26, 30 are separated from one another and the first section 26 is closed by a sealing plug. In a further method step, an exhaust gas recirculation valve is connected to the exhaust gas recirculation cooler 28 with a hose. In a next process step, a plug is removed from the exhaust gas recirculation valve and the exhaust gas recirculation valve is locked in an open position. In a next method step, a temperature sensor is removed in the exhaust gas recirculation line 30 upstream of the exhaust gas recirculation cooler 28 and upstream of the exhaust gas recirculation valve, so that the opening 54 is exposed. At the same time, a rinsing agent, in particular a pressure rinsing bottle, is filled with a rinsing fluid based on an aqueous neutral cleaner. The pressure flush bottle is then attached to the opening 54 and an operating pressure of approx. 3 bar is built up in the pressure flush bottle.

In einem folgenden Verfahrensschritt wird der Verbrennungsmotor 10 gestartet und auf eine Spüldrehzahl von 2000 U/min bis 3000 U/min, vorzugsweise von 2500 U/min beschleunigt, wobei eine Überprüfung erfolgt, ob der Abgaskanal 40 tatsächlich durch den Verschluss 48 im Wesentlichen gasdicht verschlossen ist. Bei im Wesentlichen konstanter Spüldrehzahl des Verbrennungsmotors 10 wird das Spülfluid von der Druckspülflasche in die Abgasrückführungsleitung 30 eingebracht, wobei der Druck in der Druckspülflasche nachgeführt wird, um einen Druckabfall zu vermeiden. Nachdem die Druckspülflasche vollständig entleert ist, wird der Verbrennungsmotor 10 nach einer kurzen Nachlaufphase von 2 s - 10 s, vorzugsweise von etwa 5 s abgeschaltet. Bei Bedarf kann eine weitere Druckspülflasche an die Abgasrückführungsleitung 30 angeschlossen werden und ein weiterer Spülzyklus durchgeführt werden. Ist der Spülprozess der Abgasrückführungsleitung 30 und des Abgasrückführungskühlers 28 erfolgreich abgeschlossen, so wird der Verbrennungsmotor 10 wieder in den Zustand für den Normalbetrieb zurückversetzt.In a subsequent process step, the internal combustion engine 10 is started and accelerated to a flushing speed of 2000 rpm to 3000 rpm, preferably 2500 rpm, a check being carried out to determine whether the exhaust gas duct 40 is actually essentially gas-tight by the closure 48 is. At an essentially constant flushing speed of the internal combustion engine 10, the flushing fluid is introduced from the pressure flushing bottle into the exhaust gas recirculation line 30, the pressure in the pressure flushing bottle being tracked in order to avoid a pressure drop. After the pressure flushing bottle has been completely emptied, the internal combustion engine 10 is switched off after a short run-on phase of 2 s-10 s, preferably about 5 s. If necessary, another pressure flush bottle can be connected to the exhaust gas recirculation line 30 and another flush cycle can be carried out. If the flushing process of the exhaust gas recirculation line 30 and the exhaust gas recirculation cooler 28 has been successfully completed, the internal combustion engine 10 is reset to the state for normal operation.

BezugszeichenlisteList of reference symbols

1010
VerbrennungsmotorInternal combustion engine
1212th
Einlassinlet
1414th
AuslassOutlet
1616
FrischgasleitungFresh gas line
1818th
Verdichtercompressor
2020th
LadeluftkühlerIntercooler
2222nd
EinmündungConfluence
2424
VerschlussClasp
2626th
AbgasrückführungsleitungExhaust gas recirculation line
2828
AbgasrückführungskühlerExhaust gas recirculation cooler
3030th
AbgasrückführungsleitungExhaust gas recirculation line
3232
Turbineturbine
3434
AbgasturboladerExhaust gas turbocharger
3636
OxidationskatalysatorOxidation catalyst
3838
PartikelfilterParticle filter
4040
AbgaskanalExhaust duct
4242
DifferenzdruckleitungDifferential pressure line
4444
DifferenzdruckleitungDifferential pressure line
4646
DifferenzdrucksensorDifferential pressure sensor
4848
VerschlussClasp
5050
SpülbehälterRinsing container
5252
AbsaugtrichterSuction funnel
5454
Öffnungopening
5656
Öffnungopening

Claims (9)

  1. Method for cleaning an exhaust gas recirculation line (26, 30) and/or an exhaust gas recirculation cooler (28) at an internal combustion engine (10), comprising the following steps:
    - throttling of an exhaust gas stream through the exhaust gas duct (40) or closing of the exhaust gas duct (40), in order to increase the exhaust gas stream which is conducted through the exhaust gas recirculation line (26, 30),
    - disconnecting of the exhaust gas recirculation line (26, 30), wherein a first exhaust gas recirculation line portion (26) of the exhaust gas recirculation line (26, 30) is disconnected from a second exhaust gas recirculation line portion (30),
    - closing of the open end of the first exhaust gas recirculation line portion (26) by way of a further closure, with the result that an entry into the air supply system of the internal combustion engine (10) is prevented,
    - connecting of the open end of the second exhaust gas recirculation line portion (30) to a flushing container (50),
    - connection of a flushing medium to an opening (54, 56) on the second exhaust gas recirculation line portion (30) or the exhaust gas duct (40) upstream in the flushing direction of an exhaust gas recirculation cooler (28) and upstream of an exhaust gas recirculation valve of the exhaust gas recirculation line (26, 30),
    - introducing of a flushing fluid (58) into the second exhaust gas recirculation line portion (30), wherein the exhaust gas recirculation cooler (28), the exhaust gas recirculation valve and the second exhaust gas recirculation line portion (30) are freed from contaminants and deposits.
  2. Method according to Claim 1, characterized in that, before an exhaust gas recirculation cleaning operation is carried out, the fouling state of the second exhaust gas recirculation line portion (30), of the exhaust gas recirculation valve and/or of the exhaust gas recirculation cooler (28) is determined and a method is initiated if the fouling state has reached or exceeded a defined threshold value for the fouling.
  3. Method according to Claim 1 or Claim 2, characterized in that the flushing fluid is introduced into at least one of the openings (54, 56) in the case of a running internal combustion engine (10).
  4. Method according to Claim 3, characterized in that the internal combustion engine (10) is operated at a threshold rotational speed during the cleaning operation, the threshold rotational speed lying above an idling rotational speed of the internal combustion engine (10).
  5. Method according to either of Claims 3 and 4, characterized in that the internal combustion engine (10) is switched off when the flushing medium has been emptied completely into the second exhaust gas recirculation line portion (30).
  6. Method according to one of Claims 1 to 5, characterized in that the flushing fluid (58) is an aqueous solution of a neutral cleaner with a mixing ratio of from 80 to 95 per cent by volume water and from 5 to 20 per cent by volume natural cleaner.
  7. Method according to one of Claims 1 to 6, characterized in that the flushing fluid is introduced into one of the openings (54, 56) at a pressure of from 2 to 5 bar.
  8. Method according to one of Claims 1 to 7, characterized in that the openings (54, 56) are closed during normal operation of the internal combustion engine (10) in each case by way of a sensor, in particular by way of a temperature sensor or an actuator for an exhaust gas recirculation valve.
  9. Method according to one of Claims 1 to 8, characterized in that, after a flushing operation, the residual fouling of the second exhaust gas recirculation line portion (30), of the exhaust gas recirculation valve and/or of the exhaust gas recirculation cooler (28) is measured, and the method is repeated until the residual fouling lies below a permissible threshold value.
EP18179480.1A 2017-06-30 2018-06-25 Method for cleaning an exhaust gas recirculation line and/or an exhaust gas recircvulation cooler Active EP3421775B1 (en)

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DE102017114694.6A DE102017114694A1 (en) 2017-06-30 2017-06-30 Method for cleaning an exhaust gas recirculation line and / or an exhaust gas recirculation cooler and exhaust gas recirculation system

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Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6478036B1 (en) * 1998-12-10 2002-11-12 Bg Products, Inc. Method and apparatus for cleaning exhaust gas recirculation system
FR2885178A1 (en) * 2005-04-27 2006-11-03 Renault Sas Power train for motor vehicle, has exhaust gas recirculation valves and back pressure valve circulating exhaust gas in cleaning circuit and evacuating gas in exhaust pipe, where circuit cleans section of exhaust gas recirculation circuit
DE602005013587D1 (en) 2005-11-29 2009-05-07 Renault Trucks EXHAUST GAS RECYCLING SYSTEM AND METHOD FOR CLEANING SUCH A SYSTEM
US9249377B2 (en) * 2013-05-07 2016-02-02 Bg Intellectual, Inc. Cleaning formula for motor vehicle intake and exhaust systems
DE102014001457A1 (en) * 2014-02-05 2015-03-05 Mtu Friedrichshafen Gmbh Method and device for cleaning a heat exchanger, in particular an exhaust gas recooler for cooling an exhaust gas flow of an exhaust gas recirculation
US9528475B2 (en) * 2014-11-11 2016-12-27 Ford Global Technologies, Llc Method and system for EGR control
JP2017031815A (en) * 2015-07-29 2017-02-09 いすゞ自動車株式会社 Engine egr cooler and method of washing egr cooler
JP2017031816A (en) * 2015-07-29 2017-02-09 いすゞ自動車株式会社 Engine, and cleaning method of egr cooler of engine

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