WO2005073525A1 - Method for controlling an internal combustion engine - Google Patents

Method for controlling an internal combustion engine Download PDF

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Publication number
WO2005073525A1
WO2005073525A1 PCT/SE2005/000055 SE2005000055W WO2005073525A1 WO 2005073525 A1 WO2005073525 A1 WO 2005073525A1 SE 2005000055 W SE2005000055 W SE 2005000055W WO 2005073525 A1 WO2005073525 A1 WO 2005073525A1
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WO
WIPO (PCT)
Prior art keywords
regeneration
aftertreatment device
engine
particle filter
exhaust
Prior art date
Application number
PCT/SE2005/000055
Other languages
French (fr)
Inventor
Paulina TENGSTRÖM
Andreas Hinz
Carl-Johan Karlsson
Original Assignee
Volvo Lastvagnar Ab
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Filing date
Publication date
Application filed by Volvo Lastvagnar Ab filed Critical Volvo Lastvagnar Ab
Publication of WO2005073525A1 publication Critical patent/WO2005073525A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0828—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents characterised by the absorbed or adsorbed substances
    • F01N3/0842—Nitrogen oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0821—Exhaust 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0871—Regulation of absorbents or adsorbents, e.g. purging
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0871—Regulation of absorbents or adsorbents, e.g. purging
    • F01N3/0878—Bypassing absorbents or adsorbents
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0871—Regulation of absorbents or adsorbents, e.g. purging
    • F01N3/0885—Regeneration of deteriorated absorbents or adsorbents, e.g. desulfurization of NOx traps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • F01N9/002—Electrical control of exhaust gas treating apparatus of filter regeneration, e.g. detection of clogging
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2410/00—By-passing, at least partially, exhaust from inlet to outlet of apparatus, to atmosphere or to other device
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2410/00—By-passing, at least partially, exhaust from inlet to outlet of apparatus, to atmosphere or to other device
    • F01N2410/04—By-passing, at least partially, exhaust from inlet to outlet of apparatus, to atmosphere or to other device during regeneration period, e.g. of particle filter
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/04—Sulfur or sulfur oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/14—Nitrogen oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/36—Arrangements for supply of additional fuel
    • 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
    • F02B29/00—Engines characterised by provision for charging or scavenging not provided for in groups F02B25/00, F02B27/00 or F02B33/00 - F02B39/00; Details thereof
    • F02B29/04—Cooling of air intake supply
    • F02B29/0406—Layout of the intake air cooling or coolant circuit
    • 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
    • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
    • 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
    • F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
    • F02M26/05—High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
    • 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
    • F02M26/23—Layout, e.g. schematics
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Definitions

  • the present invention relates to a method for controlling a piston-type internal combustion engine having an intake line for delivering air to combustion chambers of the engine and an exhaust system for removing exhaust gases from said combustion chambers, the exhaust system comprising a regenerable particle filter and a regenerable device for NO x aftertreatment for reducing environmentally harmful exhaust emissions from the engine, which is intended to function with variable load in order to propel a vehicle.
  • the quantity of nitrogen oxides formed by the combustion of fuel in an engine cylinder depends on the combustion temperature. Higher temperatures lead to a greater proportion of the atmospheric nitrogen being converted into nitrogen oxides.
  • a known engine-based method of reducing the quantity of nitrogen dioxide formed is so-called Exhaust Gas Recirculation (EGR) and in particular cooled EGR, which makes it possible to reduce the combustion temperature. This method is normally not sufficient, however, to meet the statutory requirements when the engine is operating at high load.
  • EGR Exhaust Gas Recirculation
  • This method of cooled Exhaust Gas Recirculation (EGR) places an increased load on the engine cooling system and the vehicle cooling system, especially at high engine loads. This constitutes a limit to the attainment of a high power output whilst achieving lower emissions.
  • NO x aftertreatment device for example LNA (Lean NO x Adsorber) to store NO x whilst the engine runs with excess oxygen.
  • the NO x aftertreatment device is regenerated by allowing the engine to run with deficient oxygen, that is to say with extra fuel admixture and/or reduced air flow, as described in US 5,473,887, for example .
  • LNC Lean NO x Catalyst
  • a problem with NO x aftertreatment devices is that they are exposed to sulfur contamination, which means that sulfur in the exhaust gases forms sulfates, which reduce the capacity to store NO x in the NO x aftertreatment device.
  • Sulfur regeneration can be achieved by reducing the excess-air factor (Lambda) and increasing the temperature to at least approximately 600°C upstream of the NO x aftertreatment device. This sulfur regeneration is not performed as frequently as N0 X regeneration, but owing to the high temperature the process nevertheless entails a significant so-called fuel penalty.
  • An object of the invention is therefore to provide a method which reduces the fuel penalty in sulfur regeneration.
  • the internal combustion engine 10 comprises an engine block 11 having six piston cylinders 12 together with inlet manifold 13 and exhaust manifold 14. Exhaust gases from the engine are fed via an exhaust line 15 to a turbine rotor 17 of a turbocharger unit 16.
  • the turbine shaft 18 drives the compressor wheel 19 of the turbocharger unit, which by way of an intake line 20 compresses incoming air and delivers it to the inlet manifold 13 via an air intercooler 21.
  • Fuel is fed to each cylinder 12 via injection devices (not shown) .
  • Exhaust gases that have passed through the turbocharger unit 16 are led onwards by way of the exhaust line 22 to a filter device 23 to separate particles from the exhaust gas flow. Downstream of the filter device is a three-way valve 24, which according to the prior art may conduct the exhaust gases either via a branch pipe 25 or via a branch pipe 26, the two branch pipes running parallel and being reunited downstream at a point 27.
  • the exhaust gas flow is thereafter led onwards into the atmosphere via a so-called clean-up unit 28, which may comprise an oxidation catalytic converter which oxidizes (burns) emission residues (HC, CO, etc) .
  • This unit may take various forms according to the demands placed on it (system design) .
  • the branch pipe 25 comprises a device 29 for mixing diesel fuel into the exhaust gas flow and a downstream NO x aftertreatment device in the form of an LNA reactor 30.
  • This comprises material which adsorbs and binds N0 X during lean-burn operation within the normal temperature range of the engine. Regeneration takes place at a higher temperature than the adsorption and whenever the three- way valve 24 leads the exhaust gas flow largely through the branch pipe 26 (bypass) and only a smaller, variable secondary flow through the branch pipe 25, the device 29 delivering diesel fuel that is gasified and mixed into the exhaust gas flow and forming regeneration gas, which according to the prior art converts and releases the bound nitrogen oxide as N 2 .
  • the engine 10 has a system for returning exhaust gases to the intake side of the engine as so-called EGR gas, via a pipeline 31, in order to reduce the nitrogen oxide emission of the engine in accordance with the prior art.
  • This line comprises a valve 32, which serves both as shut-off valve and as regulating valve for regulating the EGR flow.
  • a cooler 33 for cooling the EGR gases .
  • the valves 24 and 32 are connected to an engine control unit containing control program and control data for controlling the engine with reference to input data.
  • the engine control unit is connected, for example, to sensors which detect the engine speed and the accelerator pedal position.
  • the engine control unit is designed to control the valve 24 so that at low load the exhaust gas flow is led through the branch pipe 26. ithin this load range the exhaust emissions lie at acceptable levels without further aftertreatment. In other load ranges the exhaust gas flow is led through the branch pipe 25, NO x being stored in the NO x aftertreatment device with periodic regeneration according to the prior art.
  • the carbon monoxide (CO) content increases substantially downstream of the filter device 23.
  • This increase in the CO content is due to the fact that the soot is not fully oxidized during the filter regeneration.
  • This quantity of CO can be used to regenerate the NO x aftertreatment device.
  • the CO emission that occurs during filter regeneration acts as a starting point for desulfurization of the NO x aftertreatment device, which can be completed by means of the device 29 for mixing diesel fuel into the exhaust gas flow.
  • the fall in the lambda value described above can bring the lambda value down to a value of less than 1, thereby creating favorable conditions for reduction of SO x pollutants present in the NO x aftertreatment device.
  • the fuel economy is improved in that the soot deposited in the filter device is partially oxidized to form an effective heating/regeneration gas for the NO x aftertreatment device located downstream of the filter.
  • the use of CO makes the system independent of the physical distance that may exist between the filter and the point where the NO x aftertreatment device is mounted, provided that the ignition temperature for this CO is sufficiently high in the NO x aftertreatment device located downstream of the filter device.
  • the invention has been described above in an exhaust gas system which allows the exhaust gases to bypass the NO x aftertreatment device by means of a three-way valve 24 and the branch pipe 26.
  • the invention may be used in conventional exhaust systems without bypassing.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Processes For Solid Components From Exhaust (AREA)

Abstract

The invention relates to a method for controlling a piston-type internal combustion engine (10) having an intake line (20) for delivering air to combustion chambers of the engine and an exhaust system (15, 22) for removing exhaust gases from said combustion chambers. The exhaust system comprises a regenerable particle filter (23) and a regenerable NOx aftertreatment device (30) for reducing environmentally harmful exhaust emissions from engine, which is intended to function with variable load in order to propel a vehicle. The sulfur regeneration of the aftertreatment device (30) is synchronized with the regeneration of the particle filter (23) in such a way that the regeneration of the aftertreatment device takes place largely simultaneously with the regeneration of the particle filter.

Description

Method for controlling an internal combustion engine
TECHNICAL FIELD
The present invention relates to a method for controlling a piston-type internal combustion engine having an intake line for delivering air to combustion chambers of the engine and an exhaust system for removing exhaust gases from said combustion chambers, the exhaust system comprising a regenerable particle filter and a regenerable device for NOx aftertreatment for reducing environmentally harmful exhaust emissions from the engine, which is intended to function with variable load in order to propel a vehicle.
BACKGROUND OF THE INVENTION
The statutory requirements relating to diesel engines for heavy vehicles have been tightened up and will continue to become more stringent, particularly in relation to emissions of nitrogen oxide pollutants and particulate emissions.
The quantity of nitrogen oxides formed by the combustion of fuel in an engine cylinder depends on the combustion temperature. Higher temperatures lead to a greater proportion of the atmospheric nitrogen being converted into nitrogen oxides. A known engine-based method of reducing the quantity of nitrogen dioxide formed is so- called Exhaust Gas Recirculation (EGR) and in particular cooled EGR, which makes it possible to reduce the combustion temperature. This method is normally not sufficient, however, to meet the statutory requirements when the engine is operating at high load. This method of cooled Exhaust Gas Recirculation (EGR) places an increased load on the engine cooling system and the vehicle cooling system, especially at high engine loads. This constitutes a limit to the attainment of a high power output whilst achieving lower emissions.
Another known method of reducing the quantity of nitrogen dioxide, which is based on exhaust gas aftertreatment, uses an NOx aftertreatment device, for example LNA (Lean NOx Adsorber) to store NOx whilst the engine runs with excess oxygen. The NOx aftertreatment device is regenerated by allowing the engine to run with deficient oxygen, that is to say with extra fuel admixture and/or reduced air flow, as described in US 5,473,887, for example .
Further known systems for reducing nitrogen oxides include LNC (Lean NOx Catalyst) , which continuously reduces nitrogen oxides under lean-burn conditions.
A problem with NOx aftertreatment devices is that they are exposed to sulfur contamination, which means that sulfur in the exhaust gases forms sulfates, which reduce the capacity to store NOx in the NOx aftertreatment device. Sulfur regeneration can be achieved by reducing the excess-air factor (Lambda) and increasing the temperature to at least approximately 600°C upstream of the NOx aftertreatment device. This sulfur regeneration is not performed as frequently as N0X regeneration, but owing to the high temperature the process nevertheless entails a significant so-called fuel penalty.
SUMMARY OF THE INVENTION
An object of the invention is therefore to provide a method which reduces the fuel penalty in sulfur regeneration.
This object is achieved by a method according to the characterizing part of claim 1. DESCRIPTION OF THE DRAWINGS
The invention will be described in more detail below with reference to the drawing attached, which shows a schematic representation of an internal combustion engine, in which the method according to the invention can be applied.
DESCRIPTION OF THE PREFERRED EMBODIMENTS The internal combustion engine 10 comprises an engine block 11 having six piston cylinders 12 together with inlet manifold 13 and exhaust manifold 14. Exhaust gases from the engine are fed via an exhaust line 15 to a turbine rotor 17 of a turbocharger unit 16. The turbine shaft 18 drives the compressor wheel 19 of the turbocharger unit, which by way of an intake line 20 compresses incoming air and delivers it to the inlet manifold 13 via an air intercooler 21. Fuel is fed to each cylinder 12 via injection devices (not shown) . Although the figure illustrates a six-cylinder engine, the invention can also be used in conjunction with other cylinder configurations.
Exhaust gases that have passed through the turbocharger unit 16 are led onwards by way of the exhaust line 22 to a filter device 23 to separate particles from the exhaust gas flow. Downstream of the filter device is a three-way valve 24, which according to the prior art may conduct the exhaust gases either via a branch pipe 25 or via a branch pipe 26, the two branch pipes running parallel and being reunited downstream at a point 27. The exhaust gas flow is thereafter led onwards into the atmosphere via a so-called clean-up unit 28, which may comprise an oxidation catalytic converter which oxidizes (burns) emission residues (HC, CO, etc) . This unit may take various forms according to the demands placed on it (system design) .
The branch pipe 25 comprises a device 29 for mixing diesel fuel into the exhaust gas flow and a downstream NOx aftertreatment device in the form of an LNA reactor 30. This comprises material which adsorbs and binds N0X during lean-burn operation within the normal temperature range of the engine. Regeneration takes place at a higher temperature than the adsorption and whenever the three- way valve 24 leads the exhaust gas flow largely through the branch pipe 26 (bypass) and only a smaller, variable secondary flow through the branch pipe 25, the device 29 delivering diesel fuel that is gasified and mixed into the exhaust gas flow and forming regeneration gas, which according to the prior art converts and releases the bound nitrogen oxide as N2.
The engine 10 has a system for returning exhaust gases to the intake side of the engine as so-called EGR gas, via a pipeline 31, in order to reduce the nitrogen oxide emission of the engine in accordance with the prior art. This line comprises a valve 32, which serves both as shut-off valve and as regulating valve for regulating the EGR flow. There is 'also a cooler 33 for cooling the EGR gases .
The valves 24 and 32 are connected to an engine control unit containing control program and control data for controlling the engine with reference to input data. The engine control unit is connected, for example, to sensors which detect the engine speed and the accelerator pedal position. The engine control unit is designed to control the valve 24 so that at low load the exhaust gas flow is led through the branch pipe 26. ithin this load range the exhaust emissions lie at acceptable levels without further aftertreatment. In other load ranges the exhaust gas flow is led through the branch pipe 25, NOx being stored in the NOx aftertreatment device with periodic regeneration according to the prior art.
In an active oxygen-based regeneration of a soot -filled filter the carbon monoxide (CO) content increases substantially downstream of the filter device 23. This increase in the CO content is due to the fact that the soot is not fully oxidized during the filter regeneration. This results in a fall in the lambda value downstream of the filter device. This quantity of CO can be used to regenerate the NOx aftertreatment device. In addition, the CO emission that occurs during filter regeneration acts as a starting point for desulfurization of the NOx aftertreatment device, which can be completed by means of the device 29 for mixing diesel fuel into the exhaust gas flow. The fall in the lambda value described above can bring the lambda value down to a value of less than 1, thereby creating favorable conditions for reduction of SOx pollutants present in the NOx aftertreatment device.
The fuel economy is improved in that the soot deposited in the filter device is partially oxidized to form an effective heating/regeneration gas for the NOx aftertreatment device located downstream of the filter. The use of CO makes the system independent of the physical distance that may exist between the filter and the point where the NOx aftertreatment device is mounted, provided that the ignition temperature for this CO is sufficiently high in the NOx aftertreatment device located downstream of the filter device.
The invention has been described above in an exhaust gas system which allows the exhaust gases to bypass the NOx aftertreatment device by means of a three-way valve 24 and the branch pipe 26. Alternatively, the invention may be used in conventional exhaust systems without bypassing.
The invention must not be regarded as being limited to the exemplary embodiments described above, a number of further variants and modifications being feasible without departing from the scope of the following claims.

Claims

1. A method for controlling a piston-type internal combustion engine (10) having an intake line (20) for delivering air to combustion chambers of the engine and an exhaust system (15, 22) for removing exhaust gases from said combustion chambers, the exhaust system comprising a regenerable particle filter (23) and a regenerable NOx aftertreatment device (30) for reducing environmentally harmful exhaust emissions from the engine, which is intended to function with variable load in order to propel a vehicle, characterized in that the sulfur regeneration of the aftertreatment device (30) is synchronized with the regeneration of the particle filter (23), in such a way that the regeneration of the aftertreatment device takes place largely simultaneously with the regeneration of the particle filter.
2. The method as claimed in claim 1, characterized in that a reduction in the lambda value created downstream of the particle filter (23) by the regeneration thereof is used as starting point for the sulfur regeneration of the aftertreatment device (30) .
3. The method as claimed in claim 1 or 2, characterized in that the aftertreatment system (30) is of the LNA (Lean NOx Adsorber) type.
4. The method as claimed in claim 1 or 2, characterized in that the aftertreatment system (30) is of the LNC
(Lean NOx Catalyst) type.
5. The method as claimed in any one of claims 1 to 4, characterized in that the sulfur regeneration of the aftertreatment device (30) is supported by an injector (29) for delivering hydrocarbons to an exhaust gas flow upstream of the aftertreatment device.
PCT/SE2005/000055 2004-01-28 2005-01-18 Method for controlling an internal combustion engine WO2005073525A1 (en)

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SE0400196A SE527213C2 (en) 2004-01-28 2004-01-28 Method of controlling a piston-type internal combustion engine for the purpose of simultaneously regenerating a particle filter and a NOx aftertreatment device

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2039898A1 (en) * 2007-09-24 2009-03-25 Deere & Company Continuously regenerating particulate filter for internal combustion engine
FR2933446A1 (en) * 2008-07-01 2010-01-08 Renault Sas Nitrogen oxide trap desulfurizing method for post processing of exhaust gas emitted by internal engine of motor vehicle, involves desulfurizing trap after beginning and before ending of regeneration of filter
DE102018113056B4 (en) 2017-06-02 2022-12-22 GM Global Technology Operations LLC SYSTEMS AND METHODS FOR CONTROLLING EXHAUST FLOW THROUGH A DUAL AFTERTREATMENT DEVICE

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EP1069286A2 (en) * 1999-07-14 2001-01-17 Volkswagen Aktiengesellschaft Exhaust gas purification device for internal combustion engine and regeneration method of this device
EP1072764A1 (en) * 1999-07-28 2001-01-31 Renault System and method of treating exhaust gases of a combustion engine
EP1170472A1 (en) * 2000-07-05 2002-01-09 Kemira Metalkat Oy System and method for purifying exhaust gases
WO2003002854A1 (en) * 2001-06-26 2003-01-09 N.V. Bekaert S.A. A method of desulfation of nox-adsorbers
WO2003033892A1 (en) * 2001-10-15 2003-04-24 Toyota Jidosha Kabushiki Kaisha Exhaust gas purifying device and method for internal combustion engine

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Publication number Priority date Publication date Assignee Title
DE19850757A1 (en) * 1998-08-07 2000-02-17 Volkswagen Ag Method and device for desulfating a catalyst device
EP1069286A2 (en) * 1999-07-14 2001-01-17 Volkswagen Aktiengesellschaft Exhaust gas purification device for internal combustion engine and regeneration method of this device
EP1072764A1 (en) * 1999-07-28 2001-01-31 Renault System and method of treating exhaust gases of a combustion engine
EP1170472A1 (en) * 2000-07-05 2002-01-09 Kemira Metalkat Oy System and method for purifying exhaust gases
WO2003002854A1 (en) * 2001-06-26 2003-01-09 N.V. Bekaert S.A. A method of desulfation of nox-adsorbers
WO2003033892A1 (en) * 2001-10-15 2003-04-24 Toyota Jidosha Kabushiki Kaisha Exhaust gas purifying device and method for internal combustion engine

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2039898A1 (en) * 2007-09-24 2009-03-25 Deere & Company Continuously regenerating particulate filter for internal combustion engine
FR2933446A1 (en) * 2008-07-01 2010-01-08 Renault Sas Nitrogen oxide trap desulfurizing method for post processing of exhaust gas emitted by internal engine of motor vehicle, involves desulfurizing trap after beginning and before ending of regeneration of filter
DE102018113056B4 (en) 2017-06-02 2022-12-22 GM Global Technology Operations LLC SYSTEMS AND METHODS FOR CONTROLLING EXHAUST FLOW THROUGH A DUAL AFTERTREATMENT DEVICE

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SE0400196L (en) 2005-07-29
SE0400196D0 (en) 2004-01-28

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