WO2011070647A1 - 内燃機関の排気浄化システム - Google Patents

内燃機関の排気浄化システム Download PDF

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WO2011070647A1
WO2011070647A1 PCT/JP2009/070528 JP2009070528W WO2011070647A1 WO 2011070647 A1 WO2011070647 A1 WO 2011070647A1 JP 2009070528 W JP2009070528 W JP 2009070528W WO 2011070647 A1 WO2011070647 A1 WO 2011070647A1
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Prior art keywords
pressure egr
amount
low
ammonia
passage
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PCT/JP2009/070528
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English (en)
French (fr)
Japanese (ja)
Inventor
文悟 川口
小田　富久
知美 大西
佐藤　正明
智志 小早川
健 白澤
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トヨタ自動車株式会社
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Application filed by トヨタ自動車株式会社 filed Critical トヨタ自動車株式会社
Priority to CN200980162798.7A priority Critical patent/CN102667083B/zh
Priority to PCT/JP2009/070528 priority patent/WO2011070647A1/ja
Priority to US13/514,752 priority patent/US8943802B2/en
Priority to EP09852044.8A priority patent/EP2511492B1/de
Priority to JP2011545009A priority patent/JP5472318B2/ja
Priority to EP16154693.2A priority patent/EP3043039B1/de
Publication of WO2011070647A1 publication Critical patent/WO2011070647A1/ja
Priority to US14/568,585 priority patent/US9359927B2/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
    • 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
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2006—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating
    • F01N3/2013—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating using electric or magnetic heating means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0047—Controlling exhaust gas recirculation [EGR]
    • F02D41/005—Controlling exhaust gas recirculation [EGR] according to engine operating conditions
    • 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
    • F02M26/02—EGR systems specially adapted for supercharged engines
    • F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
    • F02M26/06—Low pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust downstream of the turbocharger turbine and reintroduced into the intake system upstream 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
    • F02M26/02—EGR systems specially adapted for supercharged engines
    • F02M26/08—EGR systems specially adapted for supercharged engines for engines having two or more intake charge compressors or exhaust gas turbines, e.g. a turbocharger combined with an additional 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
    • F02M26/14—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system
    • F02M26/15—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system in relation to engine exhaust purifying apparatus
    • 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
    • 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
    • F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
    • F01N2240/36—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being an exhaust flap
    • 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
    • F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
    • F01N2240/40—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being a hydrolysis catalyst
    • 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
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
    • 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
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/14—Arrangements for the supply of substances, e.g. conduits
    • F01N2610/1453—Sprayers or atomisers; Arrangement thereof in the exhaust apparatus
    • 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
    • F02B37/12—Control of the pumps
    • F02B37/22—Control of the pumps by varying cross-section of exhaust passages or air passages, e.g. by throttling turbine inlets or outlets or by varying effective number of guide conduits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0047—Controlling exhaust gas recirculation [EGR]
    • F02D41/0065—Specific aspects of external EGR control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/04—Introducing corrections for particular operating conditions
    • F02D41/12—Introducing corrections for particular operating conditions for deceleration
    • F02D41/123—Introducing corrections for particular operating conditions for deceleration the fuel injection being cut-off
    • F02D41/126—Introducing corrections for particular operating conditions for deceleration the fuel injection being cut-off transitional corrections at the end of the cut-off period
    • 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
    • F02M26/09—Constructional details, e.g. structural combinations of EGR systems and supercharger systems; Arrangement of the EGR and supercharger systems with respect to the engine
    • F02M26/10—Constructional details, e.g. structural combinations of EGR systems and supercharger systems; Arrangement of the EGR and supercharger systems with respect to the engine having means to increase the pressure difference between the exhaust and intake system, e.g. venturis, variable geometry turbines, check valves using pressure pulsations or throttles in the air intake or exhaust 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
    • F02M26/13—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
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Definitions

  • the present invention relates to an exhaust gas purification system for an internal combustion engine, and more particularly to a technique for suppressing corrosion of intake system parts by EGR gas.
  • LPL-EGR device low-pressure EGR device
  • PH hydrogen ion index
  • JP 2008-144633 A Japanese Patent Laid-Open No. 09-324706 JP 2009-92005 A JP 2009-85011 A Japanese Patent Laid-Open No. 11-82182
  • the present invention has been made in view of the above circumstances, and in an exhaust gas purification system for an internal combustion engine equipped with a low-pressure EGR device, the chemicals of components provided in the EGR gas path are suppressed while suppressing an increase in the number of components.
  • the purpose is to provide a technology capable of suppressing changes.
  • the present invention provides an internal combustion engine having a low-pressure EGR mechanism that introduces a part of exhaust gas (low-pressure EGR gas) from an exhaust passage downstream of a centrifugal turbocharger turbine to an intake passage upstream of a compressor.
  • an ammonia-derived compound is supplied to a low-pressure EGR gas path using a supply device for supplying an ammonia-derived compound to a selective catalytic reduction catalyst.
  • the exhaust gas purification system for an internal combustion engine of the present invention includes: A selective reduction catalyst provided in an exhaust passage of the internal combustion engine; A low-pressure EGR passage that leads a part of the exhaust gas flowing in the exhaust passage downstream of the centrifugal turbocharger turbine to the intake passage upstream of the compressor as low-pressure EGR gas, and a low-pressure EGR valve that changes the cross-sectional area of the low-pressure EGR passage.
  • a low pressure EGR mechanism provided; An apparatus for supplying an ammonia-derived compound to the selective catalytic reduction catalyst, the supply apparatus being arranged so as to be able to supply the ammonia-derived compound in an exhaust passage upstream from a connection site of the low-pressure EGR passage; Control means for supplying an ammonia-derived compound from the supply device when the low-pressure EGR valve is in an open state; I was prepared to.
  • a part of the ammonia-derived compound supplied from the supply device is supplied to the intake passage through the low pressure EGR passage. Therefore, acidic substances (for example, condensed water and vaporized water of condensed water) present in the path of low-pressure EGR gas (for example, low-pressure EGR passage, intake passage, compressor, intercooler, etc.) are neutralized by the ammonia-derived compound.
  • low-pressure EGR gas for example, low-pressure EGR passage, intake passage, compressor, intercooler, etc.
  • the supply device since an existing device provided for supplying the ammonia-derived compound as the reducing agent to the selective reduction catalyst is used, the increase in the number of components can be suppressed and the components existing in the EGR gas path can be reduced. It becomes possible to suppress chemical changes.
  • the exhaust gas purification system for an internal combustion engine of the present invention may further include an acquisition unit that acquires a value that correlates with the amount of acidic substances present in the low-pressure EGR gas path.
  • the control unit may increase the supply amount of the ammonia-derived compound when the amount acquired by the acquisition unit is large compared to when the amount is small.
  • control means may increase the supply amount of the ammonia-derived compound as the hydrogen ion index (pH) of the acidic substance existing in the low-pressure EGR gas path decreases.
  • the exhaust gas purification system for an internal combustion engine may further include detection means for detecting the temperature of the low pressure EGR gas.
  • the control unit may increase the supply amount of the ammonia-derived compound when the temperature detected by the detection unit is higher than a predetermined reference temperature than when the temperature is lower.
  • the reference temperature here is, for example, the lower limit of the temperature range in which the ammonia-derived compound can be hydrolyzed.
  • ammonia-derived compound When the ammonia-derived compound is hydrolyzed, a compound having a high acid neutralization ability such as ammonia (NH 3 ) is generated. Therefore, when the supply amount of the ammonia-derived compound is adjusted according to the temperature of the low-pressure EGR gas, a large amount of the ammonia-derived compound is not supplied when the acid neutralization ability is low. Therefore, a situation where the consumption amount of the ammonia-derived compound is unnecessarily increased is avoided.
  • NH 3 ammonia
  • the control means may stop the operation of the supply device (stop the supply of the ammonia-derived compound) when the temperature detected by the detection means is lower than the reference temperature. In that case, consumption of the ammonia-derived compound can be minimized.
  • the exhaust gas purification system for an internal combustion engine may further include heating means for heating the low pressure EGR gas.
  • the control means may operate the heating means when supplying the ammonia-derived compound from the supply device.
  • the heating means is operated in this way, the ammonia-derived compound can be hydrolyzed even when the exhaust temperature is low. As a result, the opportunity to neutralize acidic substances present in the path of the low pressure EGR gas is increased.
  • the heating means may heat the selective catalytic reduction catalyst or before flowing into the selective catalytic reduction catalyst.
  • the exhaust gas may be heated.
  • the selective reduction catalyst in addition to the ammonia-derived compound supplied from the supply device, the selective reduction catalyst can be heated.
  • the selective catalytic reduction catalyst has the property of making it difficult to adsorb ammonia-derived compounds when exposed to high temperatures.
  • the selective catalytic reduction catalyst is adsorbing the ammonia-derived compound at the time when the ammonia-derived compound is supplied to the low-pressure EGR gas path.
  • the heating means directly or indirectly heats the selective reduction catalyst, in addition to the ammonia-derived compound supplied from the supply device, the ammonia-derived compound released from the selective reduction catalyst also passes through the low-pressure EGR gas path. Will be introduced.
  • the selective catalytic reduction catalyst is heated, the amount of the ammonia-derived compound introduced into the low-pressure EGR gas path is larger than when the selective catalytic reduction catalyst is not heated.
  • the amount of the ammonia-derived compound supplied from the supply device is preferably an amount obtained by subtracting the amount of the ammonia-derived compound adsorbed by the selective catalytic reduction catalyst. In this case, it is possible to avoid an excessive amount of ammonia-derived compounds introduced into the low-pressure EGR gas path, and it is possible to minimize the amount of ammonia-derived compounds supplied from the supply device.
  • the amount of the ammonia-derived compound adsorbed by the selective catalytic reduction catalyst can be calculated using parameters such as the supply amount of the ammonia-derived chemical compound and the bed temperature of the selective catalytic reduction catalyst.
  • the heating means a heater that converts electric energy into heat energy can be used.
  • the method of reducing the opening of the intake throttle valve, the method of reducing the opening of the exhaust throttle valve, and expanding the capacity of the variable displacement turbocharger (increasing the opening of the nozzle vane) can also be heated by a method of increasing the amount of EGR gas, a method of retarding the ignition timing of the fuel in the internal combustion engine, or the like.
  • the selective catalytic reduction catalyst is disposed in the exhaust passage upstream of the connection portion of the low pressure EGR gas passage, the ammonia-derived compound supplied from the supply device is hydrolyzed by the selective catalytic reduction catalyst. Therefore, in the configuration in which the selective catalytic reduction catalyst is arranged upstream of the connection portion of the low pressure EGR passage, the heating means as described above need not be provided.
  • the ammonia-derived compound supplied from the supply device may be adsorbed by the selective reduction catalyst. Therefore, when supplying an ammonia-derived compound to the low-pressure EGR gas path, it is necessary to supply more ammonia-derived compound than the amount of the ammonia-derived compound that can be adsorbed by the selective catalytic reduction catalyst.
  • the control means supplies more ammonia-derived compound from the supply device than the amount of the ammonia-derived compound that can be adsorbed by the selective catalytic reduction catalyst. It may be.
  • the selective reduction catalyst may be disposed in the exhaust passage downstream of the connection portion of the low pressure EGR passage.
  • the selective catalytic reduction catalyst becomes an exhaust resistance, the exhaust pressure upstream of the selective catalytic reduction catalyst becomes high. Therefore, it is possible to supply the ammonia-derived compound to the low pressure EGR passage without significantly reducing the opening of the exhaust throttle valve. As a result, the acidic substance in the low-pressure EGR gas path can be neutralized without significantly increasing the back pressure acting on the internal combustion engine.
  • the selective reduction catalyst is disposed in the exhaust passage downstream of the connection portion of the low pressure EGR passage, when a catalyst (for example, an oxidation catalyst) is disposed upstream of the connection portion of the low pressure EGR passage, It is desirable that the pressure loss of the catalyst be smaller than the pressure loss of the selective catalytic reduction catalyst.
  • the selective catalytic reduction catalyst is disposed in the exhaust passage downstream from the connection portion of the low pressure EGR passage
  • a dispersion plate for dispersing the ammonia-derived compound supplied from the supply device is provided in the exhaust passage
  • the dispersion plate may be disposed in the exhaust passage downstream of the connection portion of the low pressure EGR passage.
  • the exhaust pressure at the connection portion of the low pressure EGR passage is increased by the pressure loss of the selective reduction catalyst and the pressure loss of the dispersion plate.
  • the ammonia-derived compound supplied from the supply device can more easily flow into the low-pressure EGR passage.
  • the control means is provided from the supply device when the amount of low pressure EGR gas flowing through the low pressure EGR passage is small compared to when the amount is low. You may make it increase the ammonia origin compound supplied.
  • the amount of low-pressure EGR gas When the amount of low-pressure EGR gas is large, the amount of ammonia-derived compounds flowing into the low-pressure EGR passage increases and the amount of ammonia-derived compounds flowing into the selective catalytic reduction catalyst is smaller than when the amount is low. Therefore, the ammonia-derived compound supplied to the selective reduction catalyst may be insufficient.
  • the exhaust purification system of the internal combustion engine of the present invention further includes a calculation means for calculating the amount of the ammonia-derived compound flowing through the low pressure EGR passage. It may be.
  • the control means may correct the flow rate ratio between the low pressure EGR gas and the high pressure EGR gas according to the calculation result of the calculation means.
  • the high-pressure EGR mechanism referred to here includes a high-pressure EGR passage for guiding a part of the exhaust gas flowing in the exhaust passage upstream of the centrifugal turbocharger turbine to the intake passage upstream of the compressor as high-pressure EGR gas, and the high-pressure EGR And a high pressure EGR valve that changes a passage cross-sectional area of the passage.
  • the control means corrects the opening degree of the low pressure EGR valve to the opening side and corrects the opening degree of the high pressure EGR valve to the closing side.
  • the amount of low-pressure EGR gas can be increased without changing the amount of EGR gas introduced into the internal combustion engine (the total amount of low-pressure EGR and high-pressure EGR).
  • the amount of the ammonia-derived compound flowing through the low pressure EGR passage can be increased to the target value.
  • the control means corrects the opening degree of the low pressure EGR valve to the closing side and corrects the opening degree of the high pressure EGR valve to the opening side, thereby The amount of low-pressure EGR gas can be reduced without changing the amount of EGR gas introduced. As a result, the amount of the ammonia-derived compound flowing through the low pressure EGR passage can be reduced to the target value.
  • the control means of the present invention may perform a supply process that is a process of opening the low-pressure EGR valve and supplying the ammonia-derived compound from the supply device when the deceleration fuel cut control of the internal combustion engine is being executed. .
  • the low-pressure EGR gas amount can be adjusted without affecting the combustion state of the internal combustion engine. Therefore, it is possible to adjust the amount of the ammonia-derived compound flowing through the low pressure EGR passage without affecting the combustion state of the internal combustion engine.
  • the control means closes the exhaust throttle valve provided in the exhaust passage downstream of the connection portion of the low pressure EGR passage and downstream of the selective reduction catalyst. Also good. In that case, the entire amount of the ammonia-derived compound supplied from the supply device flows to the low pressure EGR passage. As a result, the acidic substance can be neutralized with the minimum amount of the ammonia-derived compound. Furthermore, the situation where ammonia-derived compounds are released into the atmosphere can also be suppressed.
  • control means reduces the amount of low-pressure EGR gas introduced into the intake passage during a predetermined period after completion of the deceleration fuel cut control when the supply process described above is performed, compared to when the supply process is not performed. May be.
  • the inside of the low-pressure EGR gas path is filled with air.
  • the path of the low-pressure EGR gas is filled with the low-pressure EGR gas.
  • the amount of oxygen introduced into the internal combustion engine is reduced when the amount of low-pressure EGR gas in the predetermined period after the completion of the deceleration fuel cut control is reduced compared to the case where the supply process is not performed. It is possible to avoid a situation that becomes too small.
  • the above-described predetermined period is a period required until the low-pressure EGR gas existing in the intake passage downstream from the connection portion of the low-pressure EGR passage is scavenged with fresh air (in other words, the connection portion of the low-pressure EGR passage). This corresponds to a period required for the oxygen concentration in the intake passage further downstream to rise to a predetermined concentration).
  • the period required until the low pressure EGR gas existing in the intake passage is scavenged is the volume of the path from the connection portion of the low pressure EGR passage to the internal combustion engine and the engine speed (in other words, the internal combustion engine sucks per unit time). Gas amount) can be calculated as a parameter.
  • the low-pressure EGR gas amount is taken into the low-pressure EGR passage from the exhaust passage. It takes some time for the low-pressure EGR gas to reach the internal combustion engine (low-pressure EGR gas transport delay). Therefore, there is a possibility that the amount of low-pressure EGR gas introduced into the internal combustion engine after a predetermined period has elapsed.
  • the exhaust gas purification system for an internal combustion engine corrects the opening degree of the high-pressure EGR valve to the open side after a predetermined period has elapsed (larger than the opening degree when the above-described supply processing is not performed). Good.
  • the path of the high pressure EGR gas is shorter than the path of the low pressure EGR gas, the high pressure EGR gas taken into the high pressure EGR path from the exhaust passage reaches the internal combustion engine earlier than the low pressure EGR gas. Therefore, when the opening degree of the high pressure EGR valve after the lapse of the predetermined period is corrected to the open side, the shortage amount of the low pressure EGR gas can be compensated by the high pressure EGR gas.
  • an exhaust gas purification system for an internal combustion engine equipped with a low pressure EGR device it is possible to suppress chemical changes in components provided in the EGR gas path while suppressing an increase in the number of components.
  • FIG. 1 is a diagram showing a schematic configuration of an exhaust gas purification system for an internal combustion engine in the present embodiment.
  • the internal combustion engine 1 shown in FIG. 1 is a compression ignition internal combustion engine (diesel engine) for driving a vehicle having four cylinders 2.
  • Each cylinder 2 of the internal combustion engine 1 is provided with a fuel injection valve 3 that directly injects fuel into the cylinder 2.
  • the internal combustion engine 1 is connected to an intake manifold 5 and an exhaust manifold 7.
  • An intake passage 4 is connected to the intake manifold 5.
  • An exhaust passage 6 is connected to the exhaust manifold 7.
  • a compressor 8 a of a centrifugal supercharger (turbocharger) 8 is installed in the intake passage 4.
  • a turbine 8 b of a turbocharger 8 is installed in the exhaust passage 6.
  • a first throttle valve 9 is provided in the intake passage 4 downstream of the compressor 8a.
  • a second throttle valve 19 is provided upstream of the compressor 8 a in the intake passage 4.
  • An intercooler 40 is provided in the intake passage 4 downstream from the compressor 8 a and upstream from the first throttle valve 9.
  • an oxidation catalyst 23, a particulate filter 24, a selective reduction catalyst 26, and an exhaust throttle valve 27 are arranged in order from the upstream side in the exhaust flow direction.
  • Selective reduction catalyst 26 selectively adsorbs polar molecules such as ammonia (NH 3), in a catalyst for reducing and purifying nitrogen oxides in the exhaust (NOx) adsorbed ammonia (NH 3) as a reducing agent is there.
  • an addition valve 25 for supplying a reducing agent to the selective reduction catalyst 26 is attached.
  • the reducing agent supplied from the addition valve 25 include liquid, gas, or solid ammonia-derived compounds.
  • an aqueous urea solution is used as the reduction supplied from the addition valve 25.
  • the addition valve 25 is an embodiment of the supply device according to the present invention.
  • the addition valve 25 adds an aqueous urea solution into the exhaust passage 6 when the selective catalytic reduction catalyst 26 is in an active state.
  • the urea aqueous solution added into the exhaust passage 6 is thermally decomposed and hydrolyzed in the exhaust gas or in the selective reduction catalyst 26 to generate ammonia (NH 3 ).
  • the ammonia (NH 3 ) thus generated is adsorbed by the selective reduction catalyst 26 and reduces nitrogen oxide (NOx) in the exhaust. It is assumed that the addition of the urea aqueous solution by the addition valve 25 is performed at a predetermined cycle.
  • the intake / exhaust system of the internal combustion engine 1 is provided with a high pressure EGR device 11 and a low pressure EGR device 15.
  • the high pressure EGR device 11 includes a high pressure EGR passage 12, a high pressure EGR valve 13, and a high pressure EGR cooler 14.
  • One end of the high-pressure EGR passage 12 is connected to the exhaust manifold 7, and the other end is connected to the downstream side of the first throttle valve 9 in the intake passage 4.
  • the high-pressure EGR valve 13 and the high-pressure EGR cooler 14 are provided in the high-pressure EGR passage 12.
  • the flow rate of the high-pressure EGR gas introduced from the exhaust manifold 7 into the intake passage 4 through the high-pressure EGR passage 12 is controlled by the high-pressure EGR valve 13.
  • the low pressure EGR device 15 includes a low pressure EGR passage 16, a low pressure EGR valve 17, and a low pressure EGR cooler 18.
  • One end of the low pressure EGR passage 16 is connected downstream of the addition valve 25 in the exhaust passage 6 and upstream of the selective reduction catalyst 26, and the other end is downstream of the second throttle valve 19 in the intake passage 4. In addition, it is connected upstream of the compressor 8a.
  • the low pressure EGR valve 17 and the low pressure EGR cooler 18 are provided in the low pressure EGR passage 16.
  • the flow rate of the low-pressure EGR gas introduced from the exhaust passage 6 into the intake passage 4 through the low-pressure EGR passage 16 is controlled by the low-pressure EGR valve 17.
  • An electronic control unit (ECU) 20 is provided in the internal combustion engine 1 configured as described above.
  • Various sensors such as a crank position sensor 21, an accelerator position sensor 22, and an exhaust temperature sensor 28 are electrically connected to the ECU 20.
  • the crank position sensor 21 is a sensor that detects the rotational position of the output shaft (crankshaft) of the internal combustion engine 1.
  • the accelerator position sensor 22 is a sensor that detects an operation amount (accelerator opening) of an accelerator pedal.
  • the exhaust temperature sensor 28 is a sensor that detects the temperature of the exhaust gas flowing through the exhaust passage 6. In the example shown in FIG. 1, the exhaust temperature sensor 28 is disposed in the exhaust passage 6 between the particulate filter 24 and the addition valve 25, but the exhaust passage 6 and the addition valve 25 upstream of the oxidation catalyst 23.
  • the exhaust passage 6 may be disposed downstream of the exhaust passage 6 or the exhaust passage 6 downstream of the selective catalytic reduction catalyst 26.
  • the ECU 20 is electrically connected to various devices such as the fuel injection valve 3, the first throttle valve 9, the second throttle valve 19, the addition valve 25, the high pressure EGR valve 13, the low pressure EGR valve 17, and the exhaust throttle valve 27. Has been.
  • the ECU 20 controls various devices based on the detection signals of the various sensors described above.
  • the ECU 20 when the internal combustion engine 1 is in an operating state, the ECU 20 periodically opens the addition valve 25 to supply a urea aqueous solution as a reducing agent to the selective catalytic reduction catalyst 26 (hereinafter referred to as “reduction”).
  • agent addition treatment a urea aqueous solution as a reducing agent to the selective catalytic reduction catalyst 26
  • the ECU 20 opens the addition valve 25 when the low-pressure EGR valve 17 is in an open state, thereby neutralizing acidic substances existing in the low-pressure EGR gas path (hereinafter referred to as “acid neutralization”). Process ”).
  • Condensed water may accumulate in the low-pressure EGR gas path.
  • the hydrogen ion index (pH) of the condensed water may decrease (strong oxidation). If condensed water with a low hydrogen ion index (pH) or vaporized condensed water (acidic substance) flows into the compressor 8a, the intercooler 40, etc. together with the low-pressure EGR gas, the compressor 8a and the intercooler 40 may be chemically changed. There is sex.
  • the selective reduction catalyst 26 is disposed in the exhaust passage 6 downstream of the connection portion of the low pressure EGR passage 16, so that the upstream end of the low pressure EGR passage 16 (low pressure EGR passage) The exhaust pressure at the connection portion between the exhaust passage 16 and the exhaust passage 6 is increased.
  • the exhaust pressure at the upstream end of the low pressure EGR passage 16 becomes high, the exhaust gas easily flows from the exhaust passage 6 to the low pressure EGR passage 16. Therefore, it is not necessary to greatly reduce the opening degree of the exhaust throttle valve 27 when the low pressure EGR valve 17 is opened. As a result, an increase in back pressure when the low pressure EGR valve 17 is opened can be minimized.
  • FIG. 2 is a flowchart showing a control routine executed by the ECU 20 when the acid neutralization process is performed.
  • This control routine is stored in advance in the ROM or the like of the ECU 20 and is periodically executed by the ECU 20.
  • the ECU 20 first executes the process of S101.
  • S101 the ECU 20 determines whether or not the low pressure EGR valve 17 is open. If a negative determination is made in S101, the ECU 20 proceeds to S103.
  • S103 the ECU 20 controls the addition valve 25 as usual. That is, the ECU 20 supplies the urea aqueous solution to the selective reduction catalyst 26 by opening the addition valve 25 at predetermined intervals.
  • the ECU 20 proceeds to S102.
  • the ECU 20 opens the addition valve 25.
  • Ammonia (NH 3 ) flowing into the low-pressure EGR passage 16 neutralizes acidic substances present in the low-pressure EGR gas path. As a result, it is possible to avoid a situation in which the compressor 8a and the intercooler 40 disposed in the low-pressure EGR gas path are in contact with the acidic substance and chemically change.
  • an addition valve 25 for supplying the reducing agent to the selective catalytic reduction catalyst 26 can be used, so new parts are added. There is no need to do.
  • the reducing agent addition process is performed when the low-pressure EGR valve 17 is opened, a part of the reducing agent flows into the low-pressure EGR passage 16, so that the reducing agent supplied to the selective reduction catalyst 26 may be insufficient. There is sex. Therefore, when the reducing agent addition process is performed when the low pressure EGR valve 17 is opened, the amount of addition of the reducing agent is increased as compared with the case where the reducing agent addition process is performed when the low pressure EGR valve 17 is closed. It may be.
  • the example in which the acid neutralization treatment is performed on condition that the low pressure EGR valve 17 is in the open state has been described.
  • the low pressure EGR valve 17 is in the low pressure state.
  • the acid neutralization treatment may be performed on condition that the temperature of the EGR gas is equal to or higher than the reference temperature.
  • the reference temperature here is a temperature that is equal to or slightly higher than the lower limit of the temperature range in which the urea aqueous solution is thermally decomposed and hydrolyzed.
  • a substance (ammonia (NH 3 )) having a high ability as a neutralizing agent can be supplied to the low-pressure EGR gas path. Therefore, it is possible to more reliably neutralize acidic substances present in the low-pressure EGR gas path.
  • the detection signal value of the exhaust temperature sensor 28 can be used as the temperature of the low-pressure EGR gas.
  • the hydrogen ion index (pH) of a substance existing in the low-pressure EGR gas path is equal to or lower than a predetermined value.
  • the above-mentioned predetermined value is a value determined based on the maximum value of the hydrogen ion index (pH) that is considered to cause a chemical change in components such as the compressor 8a and the intercooler 40. For example, from the above-described maximum value, It is set to a slightly large value.
  • a method for obtaining the hydrogen ion index (pH) of a substance existing in the low-pressure EGR gas path a method of arranging a pH sensor at a site where condensed water easily collects in the low-pressure EGR gas path, an operation history of the internal combustion engine 1 ( A method of obtaining from a map or calculation model using the engine speed, fuel injection amount, low pressure EGR gas amount, etc. as arguments, and the integrated amount of nitrogen oxide (NOx) flowing into the low pressure EGR gas path and the low pressure EGR gas Examples of the method include a map that uses the temperature in the path as an argument and a method that uses a calculation model.
  • the acid neutralization treatment may be performed with a trigger that the amount of the acidic substance existing in the low-pressure EGR gas path exceeds a predetermined threshold.
  • a map or calculation model using the operation history of the internal combustion engine 1 (accumulated amount of engine speed, fuel injection amount, low-pressure EGR gas, etc.) as an argument is used as a method for obtaining the amount of acidic substances present in the path of the low-pressure EGR gas.
  • a map or calculation model using the operation history of the internal combustion engine 1 (accumulated amount of engine speed, fuel injection amount, low-pressure EGR gas, etc.) as an argument is used.
  • a dispersion plate for dispersing the urea aqueous solution supplied from the addition valve 25 is provided in the exhaust passage 6 upstream of the selective reduction catalyst 26. It is in.
  • FIG. 3 is a diagram showing a schematic configuration of an exhaust gas purification system for an internal combustion engine in the present embodiment.
  • a dispersion plate 29 is disposed in the exhaust passage 6 upstream of the selective reduction catalyst 26 and downstream of the connection portion of the low pressure EGR passage 16.
  • Other configurations are the same as those of the first embodiment described above.
  • the dispersion plate 29 When the dispersion plate 29 is disposed in the exhaust passage 6 upstream from the selective reduction catalyst 26 and downstream from the connection portion of the low pressure EGR passage 16, the dispersion plate 29 is not provided, or the dispersion plate 29 is disposed in the low pressure EGR passage.
  • the pressure at the upstream end of the low pressure EGR passage 16 can be increased as compared with the case where the exhaust passage 6 is disposed upstream of the connection portion 16.
  • the exhaust gas (low pressure EGR gas) easily flows from the exhaust passage 6 to the low pressure EGR passage 16.
  • the opening degree of the exhaust throttle valve 27 when the low pressure EGR valve 17 is opened can be increased.
  • the difference between the first embodiment and the present embodiment described above is that an acid neutralization process is performed when the deceleration fuel cut control of the internal combustion engine 1 is in an execution state.
  • FIG. 4 is a flowchart showing a control routine executed by the ECU 20 when the acid neutralization process is performed.
  • This control routine is stored in advance in the ROM or the like of the ECU 20 and is periodically executed by the ECU 20.
  • the ECU 20 determines whether or not the deceleration fuel cut control of the internal combustion engine 1 is being executed in S201. If a negative determination is made in S201, the ECU 20 once ends this routine. On the other hand, when a positive determination is made in S201, the ECU 20 proceeds to S202.
  • the ECU 20 reads the detection signal (exhaust temperature) of the exhaust temperature sensor 28.
  • the detection means concerning this invention is implement
  • the ECU 20 proceeds to S203, and determines whether or not the exhaust gas temperature read in S202 is equal to or higher than a reference temperature.
  • the reference temperature is equal to or slightly higher than the lower limit of the temperature range in which the urea aqueous solution can be thermally decomposed and hydrolyzed.
  • the ECU 20 closes the second throttle valve 19 and the exhaust throttle valve 27. Subsequently, the ECU 20 proceeds to S205 and causes the addition valve 25 to add a predetermined amount of urea aqueous solution.
  • the aforementioned predetermined amount is a predetermined constant amount, and is a value determined in advance by an adaptation process using an experiment or the like.
  • the ECU 20 determines whether or not a termination condition for the deceleration fuel cut control is satisfied.
  • conditions for terminating the deceleration fuel cut control include a condition in which the engine speed is equal to or lower than a predetermined lower limit value, and the detection signal (accelerator opening) of the accelerator position sensor 22 is greater than zero. .
  • the ECU 20 returns the opening degree of the second throttle valve 19 and the exhaust throttle valve 27 to the normal opening degree.
  • a catalyst 30 for hydrolysis may be arranged in the exhaust passage 6 downstream from the addition valve 25 and upstream from the connection portion of the low pressure EGR passage 16. In that case, even if the exhaust temperature is lower than the reference temperature, the acid neutralization treatment can be performed as long as the hydrolysis catalyst 30 is in an active state.
  • the hydrolysis catalyst may be disposed in the low pressure EGR passage 16.
  • exhaust gas may not easily flow from the exhaust passage 6 to the low pressure EGR passage 16 due to pressure loss of the catalyst.
  • a heating device for heating the exhaust gas may be provided.
  • An example of the heating device is an electric heater that changes electric energy into heat energy.
  • the ECU 20 determines the opening degree of the low pressure EGR valve 17 in a predetermined period after the deceleration fuel cut control is completed (the operation of the internal combustion engine 1).
  • a process (hereinafter referred to as “scavenging process”) for closing the low pressure EGR valve 17 may be performed.
  • the above-mentioned predetermined period is a period required for the gas existing in the intake passage 4 downstream from the connection portion of the low pressure EGR passage 16 to be scavenged.
  • the volume of the path from the connection part of the low pressure EGR passage 16 to the combustion chamber of the internal combustion engine 1 and the engine speed are calculated as parameters. Can do.
  • the amount of oxygen introduced into the combustion chamber of the internal combustion engine 1 after completion of the deceleration fuel cut control is insufficient, or carbon dioxide (CO 2 ) or water (H 2 O) It is possible to avoid a situation where the amount is excessive. As a result, it is possible to avoid a situation in which the combustion stability of the internal combustion engine 1 is reduced or a misfire occurs after the deceleration fuel cut control is completed.
  • the amount of low-pressure EGR gas introduced into the combustion chamber of the internal combustion engine 1 is increased to the target amount (the target amount of low-pressure EGR gas when the acid neutralization process and the scavenging process are not performed). It is necessary to let However, since it takes some time for the low pressure EGR gas to reach the combustion chamber of the internal combustion engine 1, there is a possibility that the amount of low pressure EGR gas introduced into the combustion chamber of the internal combustion engine 1 after the scavenging process is insufficient. is there. If the low-pressure EGR gas is insufficient, there may be a situation where the amount of nitrogen oxide (NOx) generated increases or a situation where combustion noise increases.
  • NOx nitrogen oxide
  • the ECU 20 may correct the opening of the high-pressure EGR valve 13 after the scavenging process is opened more than the opening when the scavenging process is not executed.
  • the correction amount at that time may be a fixed amount, or may be a variable amount that is changed according to the shortage amount of the low-pressure EGR gas.
  • the example in which the acid neutralization process is performed on the condition that the deceleration fuel cut control is being performed has been described.
  • the deceleration fuel cut control is being performed and the low pressure EGR gas is in the path.
  • the acid neutralization treatment may be performed on the condition that the hydrogen ion index (pH) of the substance existing in is not more than a predetermined value. In that case, the amount of the urea aqueous solution supplied from the addition valve 25 can be minimized.
  • the difference between the first embodiment described above and the present embodiment is that the selective reduction catalyst 26 is disposed in the exhaust passage 6 upstream of the connection portion of the low pressure EGR passage 16.
  • FIG. 6 is a diagram showing a schematic configuration of an exhaust gas purification system for an internal combustion engine in the present embodiment.
  • the selective catalytic reduction catalyst 26 is disposed in the exhaust passage 6 upstream from the connection portion of the low pressure EGR passage 16 and downstream from the addition valve 25.
  • ammonia (NH 3 ) supplied from the addition valve 25 is selectively reduced. It will be adsorbed by the mold catalyst 26.
  • ammonia saturated amount the amount of adsorbable ammonia selective reduction catalyst 26 (NH 3) (hereinafter, referred to as "ammonia saturated amount") more ammonia (NH 3) Is added to the selective catalytic reduction catalyst 26 so that the addition valve 25 is controlled.
  • FIG. 7 is a flowchart showing a control routine executed by the ECU 20 when the acid neutralization process is performed.
  • This control routine is stored in advance in the ROM or the like of the ECU 20 and is periodically executed by the ECU 20.
  • the ECU 20 first determines in S301 whether or not an execution condition for the acid neutralization process is satisfied.
  • the acid neutralization execution condition is, for example, when the amount of acidic substances (ion amount or molar amount) Gac existing in the path of the low pressure EGR gas exceeds the threshold value and the low pressure EGR valve 17 is in the open state. To establish.
  • a map using an operation history of the internal combustion engine 1 an engine rotation speed, a fuel injection amount, an integrated amount of the low-pressure EGR gas, etc.
  • the obtaining means according to the present invention is realized by the ECU 20 obtaining the amount Gac of the acidic substance according to such a method.
  • the ECU 20 starts supplying the urea aqueous solution by opening the addition valve 25. At that time, the ECU 20 adjusts the supply amount of the urea aqueous solution so that more ammonia (NH 3 ) than the ammonia saturation amount of the selective reduction catalyst 26 is supplied to the selective reduction catalyst 26.
  • FIG. 8 is a diagram showing the relationship between the ammonia saturation amount of the selective reduction catalyst 26 and the bed temperature of the selective reduction catalyst 26.
  • the ammonia saturation amount of the selective reduction catalyst 26 changes according to the bed temperature of the selective reduction catalyst 26.
  • the ECU 20 calculates the ammonia saturation amount using the bed temperature of the selective reduction catalyst 26 as a parameter, and sets the addition valve 25 so that more ammonia (NH 3 ) than the ammonia saturation amount is supplied to the selective reduction catalyst 26. I tried to control it.
  • the ECU 20 calculates the total amount Gnh3lpl of ammonia (NH 3 ) flowing into the low pressure EGR passage 16 in S303. Specifically, the ECU 20 first determines the amount of ammonia (NH 3 ) flowing out from the selective reduction catalyst 26. That is, the ECU 20 obtains the concentration Cnh3rl of ammonia (NH 3 ) contained in the exhaust gas flowing out from the selective reduction catalyst 26.
  • the concentration Cnh3rl of ammonia (NH 3 ) contained in the exhaust gas may be obtained by a map or calculation model using the bed temperature of the selective catalytic reduction catalyst 26 or the exhaust gas flow rate as an argument, or the exhaust gas flow rate and the ammonia sensor. You may obtain
  • the ECU 20 calculates the amount of exhaust flowing from the exhaust passage 6 to the low pressure EGR passage 16, that is, the low pressure EGR gas amount Glpl.
  • the low-pressure EGR gas amount Glpl is obtained by a map or calculation model using as arguments the operating conditions (intake air amount or engine speed) of the internal combustion engine 1, the opening degree of the low-pressure EGR valve 17, the opening degree of the exhaust throttle valve 27, and the like. Can do.
  • the ECU 20 determines whether or not the total amount Gnh3lpl obtained in S303 is greater than or equal to the acidic substance amount Gac calculated in S301. If a negative determination is made in S304 (Gnh3lpl ⁇ Gac), the ECU 20 returns to S303 described above. On the other hand, when an affirmative determination is made in S304 (Gnh3lpl ⁇ Gac), the ECU 20 proceeds to S305 and closes the addition valve 25.
  • the ECU 20 resets the calculated value of the acidic substance amount Gac existing in the low-pressure EGR gas path to zero, and ends the execution of this routine.
  • the acidic substance existing in the low pressure EGR gas path can be neutralized.
  • the supply amount of the urea aqueous solution is adjusted according to the amount of the acidic substance existing in the path of the low pressure EGR gas, the consumption amount of the urea aqueous solution accompanying the execution of the acid neutralization treatment is necessary. Minimized.
  • the difference between the fourth embodiment described above and the present embodiment is that the exhaust throttle valve 27 is closed when the acid neutralization process is performed during the deceleration fuel cut control.
  • FIG. 9 is a flowchart showing a control routine executed when the ECU 20 performs the acid neutralization process in the present embodiment.
  • the same reference numerals are given to the processes equivalent to the control routine of the fourth embodiment described above (see FIG. 7).
  • the ECU 20 executes the process of S401 after executing the process of S302.
  • the ECU 20 determines whether or not the deceleration fuel cut control is being executed.
  • the ECU 20 proceeds to S402 where the second throttle valve 19 and the exhaust throttle valve 27 are closed and the low-pressure EGR valve 17 is opened.
  • the acid neutralization process is performed in such a state, all of the ammonia (NH 3 ) flowing out from the selective reduction catalyst 26 flows into the low pressure EGR passage 16.
  • all of the ammonia (NH 3 ) flowing out from the selective catalytic reduction catalyst 26 can be used as a neutralizing agent. As a result, it is possible to neutralize the acidic substance while suppressing the consumption amount of the urea aqueous solution accompanying the implementation of the acid neutralization treatment.
  • the ECU 20 proceeds to S403 and controls the opening of the second throttle valve 19, the exhaust throttle valve 27, and the low pressure EGR valve 17 to the normal opening.
  • the example in which the acid neutralization process is performed even when the deceleration fuel cut control is not executed has been described.
  • the acid neutralization process is performed only when the deceleration fuel cut control is performed. Also good. In that case, it is possible to further reduce the consumption of the urea aqueous solution accompanying the implementation of the acid neutralization treatment.
  • the difference between the fourth embodiment and the present embodiment is that a heating means for heating the selective reduction catalyst 26 is provided, and the heating means is operated during the acid neutralization treatment.
  • FIG. 10 is a diagram showing a schematic configuration of an exhaust gas purification system for an internal combustion engine in the present embodiment.
  • a heater 260 for heating the selective reduction catalyst 26 is attached to the selective reduction catalyst 26.
  • the heater 260 heats the selective catalytic reduction catalyst 26 by converting electric energy supplied from the battery into heat energy.
  • Other configurations are the same as those of the fourth embodiment described above.
  • the ECU 20 supplies the urea aqueous solution from the addition valve 25 and operates the heater 260.
  • the ECU 20 acquires the bed temperature of the selective catalytic reduction catalyst 26 when the conditions for executing the acid neutralization treatment are satisfied, and sets the target value (target supply amount) of the ammonia adsorption amount based on the bed temperature. decide.
  • the target supply amount is set to an amount smaller than the ammonia saturation amount.
  • the ECU 20 opens the addition valve 25 according to the target supply amount and operates the heater 260.
  • the bed temperature of the selective catalytic reduction catalyst 26 is high, the ammonia saturation amount is smaller than when the bed temperature is low. Therefore, when the selective catalytic reduction catalyst 26 is heated by the heater 260, the ammonia saturation amount falls below the target supply amount. As a result, a part of the ammonia (NH 3 ) supplied to the selective catalytic reduction catalyst 26 flows downstream from the selective catalytic reduction catalyst 26.
  • FIG. 11 shows changes in the bed temperature and the ammonia adsorption amount of the selective catalytic reduction catalyst 26 when the acid neutralization treatment is executed.
  • the solid line in FIG. 11 indicates the ammonia saturation amount, and the dashed line indicates the target value of the ammonia adsorption amount (in other words, the target supply amount of ammonia (NH 3 )).
  • tcat1 in FIG. 11 indicates the bed temperature of the selective catalytic reduction catalyst 26 when the conditions for executing the acid neutralization treatment are satisfied, and tcat2 indicates the bed temperature when the selective catalytic reduction catalyst 26 is heated by the heater 260. Show. Further, anh0 in FIG.
  • anh1 indicates the target supply amount of ammonia (NH 3 ) in the acid neutralization treatment.
  • Anh2 indicates the ammonia saturation amount (ammonia adsorption amount) when the bed temperature of the selective catalytic reduction catalyst 26 is raised to tcat2.
  • the selective reduction catalyst 26 when the selective reduction catalyst 26 is heated during the execution of the acid neutralization treatment, more ammonia than the ammonia saturation amount (ammonia saturation amount corresponding to the bed temperature at the time when the execution conditions for the acid neutralization treatment are satisfied). There is no need to supply (NH 3 ) to the selective catalytic reduction catalyst 26. As a result, it is possible to suppress an increase in the amount of urea aqueous solution consumed due to the acid neutralization treatment.
  • FIG. 12 is a flowchart illustrating a control routine executed when the ECU 20 performs the acid neutralization process.
  • the same reference numerals are assigned to the processes equivalent to the control routine (see FIG. 7) of the fourth embodiment described above.
  • the ECU 20 executes the process of S501 after executing S302.
  • the ECU 20 operates the heater 260.
  • the ECU 20 determines that the ammonia (NH 3 ) amount (target supply amount) anh1 supplied to the selective reduction catalyst 26 is the ammonia saturation amount anh0. It is assumed that the addition valve 25 is controlled so as to be smaller.
  • the ECU20 performs the process of S303 to S305 after performing the process of S501.
  • the ECU 20 uses the current bed temperature tcat, the target supply amount anh1, and the map as shown in FIG. 11 described above. Shall. That is, the ECU 20 obtains the ammonia saturation amount anh corresponding to the current bed temperature tcat from the map of FIG. Subsequently, the ECU 20 calculates the amount of ammonia (NH 3 ) flowing out from the selective reduction catalyst 26 by subtracting the ammonia saturation amount anh from the target supply amount anh1.
  • the ECU 20 executes the process of S502 after executing the process of S305.
  • the ECU 20 stops the heater 260.
  • the ammonia saturation amount is increased. Therefore, it is possible to avoid a situation in which ammonia (NH 3 ) flows out from the selective catalytic reduction catalyst 26 after completion of the acid neutralization treatment.
  • the heater attached to the selective catalytic reduction catalyst 26 is illustrated as a means for heating the selective catalytic reduction catalyst 26.
  • the heater is arranged so as to heat the exhaust flowing into the selective catalytic reduction catalyst 26. May be.
  • the control for correcting the opening of the second throttle valve 19 to the closed side, the control for increasing the low pressure EGR gas or the high pressure EGR gas, and the opening of the exhaust throttle valve 27 are closed. At least one of control for correcting the fuel injection side, control for retarding the injection timing of the fuel injection valve 3 (control for retarding the combustion timing of fuel), and control for supplying unburned fuel to the oxidation catalyst 23
  • control for correcting the fuel injection side control for retarding the injection timing of the fuel injection valve 3 (control for retarding the combustion timing of fuel)
  • control for supplying unburned fuel to the oxidation catalyst 23 By executing the ECU 20, the temperature of the exhaust gas flowing into the selective catalytic reduction catalyst 26 may be raised.
  • the ECU 20 advances the opening timing of the exhaust valve, thereby adjusting the temperature of the exhaust gas flowing into the selective catalytic reduction catalyst 26. You may make it raise.
  • the ECU 20 corrects the nozzle vane opening of the variable displacement turbocharger to the open side so that the temperature of the exhaust gas flowing into the selective reduction catalyst 26 is increased. May be.
  • the difference between the sixth embodiment described above and the present embodiment is that the exhaust throttle valve 27 is closed when the acid neutralization process is performed during the deceleration fuel cut control.
  • FIG. 13 is a flowchart showing a control routine executed when the ECU 20 performs the acid neutralization process in this embodiment.
  • the same reference numerals are given to the processes equivalent to the control routine (see FIG. 12) of the sixth embodiment described above.
  • the ECU 20 executes the processes of S601 to S603 before executing the process of S302.
  • the ECU 20 determines whether or not deceleration fuel cut control is being executed.
  • the ECU 20 proceeds to S602, where the second throttle valve 19 and the exhaust throttle valve 27 are closed and the low-pressure EGR valve 17 is opened.
  • the acid neutralization process is performed in such a state, all of the ammonia (NH 3 ) flowing out from the selective reduction catalyst 26 flows into the low pressure EGR passage 16.
  • all of the ammonia (NH 3 ) flowing out from the selective catalytic reduction catalyst 26 can be used as a neutralizing agent. As a result, it is possible to neutralize the acidic substance while suppressing the consumption amount of the urea aqueous solution accompanying the implementation of the acid neutralization treatment.
  • the ECU 20 proceeds to S603, and controls the opening of the second throttle valve 19, the exhaust throttle valve 27, and the low pressure EGR valve 17 to the normal opening.
  • the example in which the acid neutralization process is performed even when the deceleration fuel cut control is not executed has been described.
  • the acid neutralization process is performed only when the deceleration fuel cut control is performed. Also good. In that case, it is possible to further reduce the consumption of the urea aqueous solution accompanying the implementation of the acid neutralization treatment.
  • the difference between the first embodiment described above and the present embodiment is that the amount of urea aqueous solution supplied from the addition valve 25 is adjusted (corrected) in accordance with the amount of low-pressure EGR gas when the acid neutralization process is performed. In the point.
  • the amount of aqueous urea solution (amount of ammonia) flowing into the selective catalytic reduction catalyst 26 varies depending on the amount of low-pressure EGR gas. That is, when the amount of the low-pressure EGR gas is large, the amount of the urea aqueous solution flowing into the selective catalytic reduction catalyst 26 is smaller than when the amount is low. If the amount of the urea aqueous solution flowing into the selective catalytic reduction catalyst 26 becomes too small, the selective catalytic reduction catalyst 26 may not be able to completely purify nitrogen oxide (NOx) in the exhaust gas.
  • NOx nitrogen oxide
  • the amount of the aqueous urea solution supplied from the addition valve 25 is increased when the amount of the low-pressure EGR gas is large compared to when the amount is low. According to such a method, even when the aqueous urea solution is supplied from the addition valve 25 when the acid neutralization process is performed (when the low pressure EGR valve 17 is opened), the necessary amount is supplied to the selective reduction catalyst 26. Of ammonia (NH 3 ) can be supplied.
  • FIG. 14 is a flowchart illustrating a control routine executed when the ECU 20 performs the acid neutralization process.
  • the same reference numerals are given to the processes equivalent to the control routine (see FIG. 2) of the first embodiment described above.
  • the ECU 20 executes the process of S701 when an affirmative determination is made in S101.
  • the ECU 20 calculates the amount anhscr of ammonia (NH 3 ) supplied to the selective catalytic reduction catalyst 26 when it is assumed that a predetermined amount of urea aqueous solution has been added into the exhaust gas from the addition valve 25.
  • the predetermined amount here may be a predetermined constant amount, or a variable amount determined by using the amount of acidic substance present in the low-pressure EGR gas path or the hydrogen ion index (pH) as a parameter. May be.
  • the ECU 20 In calculating the amount of ammonia (NH 3 ) anhscr supplied to the selective catalytic reduction catalyst 26, the ECU 20 first sets the amount of urea aqueous solution supplied from the addition valve 25 and the exhaust gas flow rate Gex as parameters in the exhaust gas. The concentration of ammonia (NH 3 ) contained is calculated. Subsequently, the ECU 20 calculates the amount of exhaust flowing from the exhaust passage 6 to the low pressure EGR passage 16, that is, the low pressure EGR gas amount Glpl.
  • the low-pressure EGR gas amount Glpl is obtained by a map or calculation model using as arguments the operating conditions (intake air amount or engine speed) of the internal combustion engine 1, the opening degree of the low-pressure EGR valve 17, the opening degree of the exhaust throttle valve 27, and the like. Can do.
  • the ECU 20 proceeds to S702.
  • the ECU 20 determines whether or not the difference between the ammonia (NH 3 ) supply amount anhscr obtained in S701 and the ammonia adsorption amount target value anhtrg is smaller than an allowable value.
  • the ECU 20 proceeds to S102, where a predetermined amount of urea aqueous solution is supplied from the addition valve 25.
  • the ECU 20 proceeds to S703 and corrects the predetermined amount. Specifically, when the supply amount anhscr is smaller than the target value anhtrg, the ECU 20 increases and corrects the predetermined amount. On the other hand, if the supply amount anhscr is greater than the target value anhtrg, the predetermined amount is corrected to decrease.
  • the ECU 20 proceeds to S102 after executing the processing of S703, and operates the addition valve 25 according to the predetermined amount corrected in S703.
  • the acid neutralization treatment can be executed without reducing the purification ability of the selective catalytic reduction catalyst 26.
  • the acidic substance in the low-pressure EGR gas path can be neutralized without increasing the exhaust emission of the internal combustion engine 1.
  • the difference between the first embodiment described above and the present embodiment is that the low pressure EGR gas and the high pressure EGR are changed according to the amount of ammonia (NH 3 ) flowing into the low pressure EGR passage 16 when the acid neutralization process is performed.
  • the point is to adjust the flow ratio with the gas.
  • the ECU 20 has a flow ratio of the low pressure EGR gas to the high pressure EGR gas when the amount of ammonia (NH 3 ) supplied to the low pressure EGR passage 16 is insufficient. Was corrected to increase.
  • the amount of ammonia (NH 3 ) supplied to the low pressure EGR gas path can be increased without changing the amount of EGR gas introduced into the internal combustion engine 1 (the total amount of the low pressure EGR gas amount and the high pressure EGR gas amount). it can.
  • the amount of ammonia (NH 3 ) supplied to the low pressure EGR passage 16 is excessive, the flow rate ratio of the low pressure EGR gas to the high pressure EGR gas is corrected to decrease. In that case, the amount of ammonia (NH 3 ) supplied to the low-pressure EGR gas path can be reduced without changing the amount of EGR gas introduced into the internal combustion engine 1.
  • FIG. 15 is a flowchart showing a subroutine executed by the ECU 20 during or before execution of the acid neutralization process.
  • the ECU 20 calculates the amount Gac of the acidic substance existing in the low-pressure EGR gas path.
  • the acidic substance amount Gac can be obtained by the same method as in the fourth embodiment described above.
  • the ECU 20 calculates the amount Ghn3lpl of ammonia (NH 3 ) flowing into the low pressure EGR passage 16 based on the ratio ⁇ calculated in S801.
  • the ECU 20 performs the above calculation on the assumption that a predetermined amount of urea aqueous solution has been added from the addition valve 25.
  • the ECU 20 calculates a correction amount ⁇ C for correcting the ratio ⁇ of the low pressure EGR gas amount to the total EGR gas amount.
  • the correction amount ⁇ C may be a predetermined constant amount, or a variable amount that is set to a larger value when the absolute value of the difference ⁇ G calculated at S804 is large than when it is small. Also good.
  • the ECU 20 determines whether or not the difference ⁇ G calculated in S804 is greater than zero. If an affirmative determination is made in S806 ( ⁇ G> 0), the ECU 20 proceeds to S807. In S807, the ECU 20 subtracts the correction amount ⁇ C from the ratio ⁇ obtained in S801, thereby reducing and correcting the ratio ⁇ of the low pressure EGR gas amount to the total EGR gas amount. In that case, the amount of high-pressure EGR gas is increased and the amount of low-pressure EGR gas is decreased. As a result, the amount of ammonia (NH 3 ) supplied to the low pressure EGR passage 16 decreases without changing the total EGR gas amount.
  • NH 3 ammonia
  • the ECU 20 proceeds to S808 and determines whether or not ⁇ G is smaller than zero. If an affirmative determination is made in S808 ( ⁇ G ⁇ 0), the ECU 20 proceeds to S809. In S809, the correction amount ⁇ C is added to the ratio ⁇ obtained in S801, thereby increasing the low-pressure EGR gas amount ratio ⁇ with respect to the total EGR gas amount. In that case, the high-pressure EGR gas amount is reduced and the low-pressure EGR gas amount is increased. As a result, the amount of ammonia (NH 3 ) supplied to the low-pressure EGR passage 16 increases without changing the total EGR gas amount.
  • NH 3 ammonia
  • the low pressure EGR mechanism when the low pressure EGR mechanism is in an inoperative state (when the low pressure EGR valve 17 is in a closed state) or when the flow rate ratio of the low pressure EGR gas amount to the high pressure EGR gas amount is low. Even if it exists, it becomes possible to neutralize the acidic substance in a low pressure EGR gas path.
  • the ratio ⁇ of the low pressure EGR gas amount may be corrected to be increased on the condition that the temperature of the gas introduced into the combustion chamber of the internal combustion engine 1 is higher than the lower limit value.
  • the ECU 20 may correct the low-pressure EGR gas amount ratio ⁇ in accordance with a subroutine as shown in FIG.
  • S901 is executed when an affirmative determination is made in S808 ( ⁇ G ⁇ 0).
  • the ECU 20 determines whether or not the temperature Tin of the gas introduced into the combustion chamber of the internal combustion engine 1 is equal to or higher than the lower limit temperature Tinlt.
  • the temperature Tin of the gas introduced into the combustion chamber of the internal combustion engine 1 the temperature of the gas in the intake passage 4 downstream from the connection portion of the high pressure EGR passage 12 (for example, the temperature in the intake manifold 5) is used. Can do.
  • the temperature in the intake manifold 5 may be measured by a temperature sensor. Further, the temperature in the intake manifold 5 is obtained by using a map or an arithmetic model using an intake air amount, an intake air temperature, a high pressure EGR gas amount, a high pressure EGR gas temperature, a low pressure EGR gas amount, a low pressure EGR gas temperature and the like as arguments. May be.
  • the above-described lower limit temperature Tinlt is the lowest temperature in a temperature range where misfire cannot occur, or a temperature slightly higher than the lowest temperature, and is determined in advance by adaptation work using experiments or the like.
  • the ratio ⁇ of the low-pressure EGR gas amount is corrected to increase only when the occurrence of misfire can be avoided. Therefore, it is possible to avoid a decrease in drivability of the internal combustion engine 1 due to the execution of the acid neutralization process.
  • the low pressure EGR gas is controlled to flow around the low pressure EGR cooler 18, or the high pressure EGR gas flows around the high pressure EGR cooler 14.
  • the ratio ⁇ may be corrected so as to increase while controlling. Further, the ratio ⁇ may be corrected by increasing the temperature while increasing the temperature of the low pressure EGR gas and the high pressure EGR gas by adjusting the fuel injection timing.
  • the ratio ⁇ of the low pressure EGR gas amount decreases (increases the high pressure EGR gas amount) in the operation region where only the low pressure EGR mechanism operates or in the operation region where both the high pressure EGR mechanism and the low pressure EGR mechanism operate, the high pressure It is assumed that parts in the EGR gas path (for example, the high-pressure EGR valve 13) are overheated, or fuel is prematurely ignited due to an increase in the compression end temperature.
  • the ratio ⁇ of the low-pressure EGR gas amount may be corrected to decrease on the condition that the temperature of the high-pressure EGR gas is lower than the upper limit value.
  • the ECU 20 may correct the low-pressure EGR gas amount ratio ⁇ in accordance with a subroutine as shown in FIG.
  • S1001 is executed when an affirmative determination is made in S806 ( ⁇ G> 0).
  • the ECU 20 determines whether or not the temperature Thv of the high-pressure EGR gas is equal to or lower than the upper limit temperature Thvlt.
  • the temperature Thv of the high pressure EGR gas the temperature of the high pressure EGR gas in the vicinity of the high pressure EGR valve 13 can be used.
  • the high pressure EGR gas temperature in the vicinity of the high pressure EGR valve 13 may be measured by a temperature sensor, or may be calculated from the operating state (engine speed or fuel injection amount) of the internal combustion engine 1.
  • the above-described upper limit temperature Thvlt is lower than the maximum temperature in the temperature range where the high pressure EGR valve 13 or the like does not overheat, the maximum temperature in the temperature range where the premature ignition of the fuel can be avoided, or slightly lower than that temperature. It is the temperature, and is determined in advance by an adaptation work using experiments or the like.
  • the ECU 20 If the ECU 20 makes an affirmative determination in S1001 (Thv ⁇ Thvlt), the ECU 20 proceeds to S807 and corrects the ratio ⁇ of the low-pressure EGR gas amount to decrease. However, if a negative determination is made in S1001 (Thv> Thvlt), the execution of this routine is terminated without correcting the low-pressure EGR gas amount ratio ⁇ .
  • the ratio ⁇ of the low pressure EGR gas amount is corrected to be reduced only when it is possible to avoid overheating of the components arranged in the high pressure EGR gas path and premature ignition of the fuel. Will be. Therefore, it is possible to avoid deterioration of parts and drivability reduction of the internal combustion engine 1 due to execution of the acid neutralization treatment.
  • the ratio ⁇ may be corrected to decrease. Further, the ratio ⁇ may be corrected to decrease while the temperature of the low pressure EGR gas and the high pressure EGR gas is lowered by adjusting the fuel injection timing.

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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)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Exhaust-Gas Circulating Devices (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
PCT/JP2009/070528 2009-12-08 2009-12-08 内燃機関の排気浄化システム WO2011070647A1 (ja)

Priority Applications (7)

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CN200980162798.7A CN102667083B (zh) 2009-12-08 2009-12-08 内燃机的排气净化系统
PCT/JP2009/070528 WO2011070647A1 (ja) 2009-12-08 2009-12-08 内燃機関の排気浄化システム
US13/514,752 US8943802B2 (en) 2009-12-08 2009-12-08 Exhaust gas purification system for an internal combustion engine
EP09852044.8A EP2511492B1 (de) 2009-12-08 2009-12-08 Abgasemissionssteuerungssystem für einen verbrennungsmotor
JP2011545009A JP5472318B2 (ja) 2009-12-08 2009-12-08 内燃機関の排気浄化システム
EP16154693.2A EP3043039B1 (de) 2009-12-08 2009-12-08 Abgasreinigungssystem für einen verbrennungsmotor
US14/568,585 US9359927B2 (en) 2009-12-08 2014-12-12 Exhaust gas purification system for an internal combustion engine

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US14/568,585 Division US9359927B2 (en) 2009-12-08 2014-12-12 Exhaust gas purification system for an internal combustion engine

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JP2015068274A (ja) * 2013-09-30 2015-04-13 マツダ株式会社 エンジンの排気ガス還流制御装置
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JP6230010B1 (ja) * 2016-08-03 2017-11-15 マツダ株式会社 エンジンの排気浄化装置
JP2018021499A (ja) * 2016-08-03 2018-02-08 マツダ株式会社 エンジンの排気浄化装置

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US20120240557A1 (en) 2012-09-27
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US20150113985A1 (en) 2015-04-30
JP5472318B2 (ja) 2014-04-16
JPWO2011070647A1 (ja) 2013-04-22
EP2511492B1 (de) 2016-05-04
US9359927B2 (en) 2016-06-07
EP2511492A1 (de) 2012-10-17
EP3043039B1 (de) 2017-12-06
EP3043039A1 (de) 2016-07-13
CN102667083B (zh) 2015-03-25
CN102667083A (zh) 2012-09-12

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