WO2014102932A1 - 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 PDFInfo
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- WO2014102932A1 WO2014102932A1 PCT/JP2012/083659 JP2012083659W WO2014102932A1 WO 2014102932 A1 WO2014102932 A1 WO 2014102932A1 JP 2012083659 W JP2012083659 W JP 2012083659W WO 2014102932 A1 WO2014102932 A1 WO 2014102932A1
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- filter regeneration
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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
- F01N3/02—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
- F01N3/025—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 using fuel burner or by adding fuel to exhaust
- F01N3/0253—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 using fuel burner or by adding fuel to exhaust adding fuel to exhaust gases
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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
- 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
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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
- F01N3/02—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
- F01N3/033—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 in combination with other devices
- F01N3/035—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 in combination with other devices with catalytic reactors, e.g. catalysed diesel particulate filters
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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
- F01N3/105—General auxiliary catalysts, e.g. upstream or downstream of the main catalyst
- F01N3/106—Auxiliary oxidation catalysts
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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]
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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
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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
- 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
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/021—Introducing corrections for particular conditions exterior to the engine
- F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
- F02D41/024—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus
- F02D41/0245—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus by increasing temperature of the exhaust gas leaving the engine
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/021—Introducing corrections for particular conditions exterior to the engine
- F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
- F02D41/027—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus
- F02D41/029—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus the exhaust gas treating apparatus being a particulate filter
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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
- F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
- F01N2560/06—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being a temperature sensor
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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
- F01N2610/00—Adding substances to exhaust gases
- F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
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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
- F01N2610/00—Adding substances to exhaust gases
- F01N2610/03—Adding substances to exhaust gases the substance being hydrocarbons, e.g. engine fuel
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- 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
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- 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.
- an exhaust purification device provided in an exhaust passage of an internal combustion engine has been developed in which a filter carries a selective reduction type NOx catalyst (hereinafter referred to as an SCR catalyst).
- the filter collects particulate matter (hereinafter referred to as PM) in the exhaust.
- the SCR catalyst reduces NOx in the exhaust gas using ammonia (NH 3 ) as a reducing agent.
- a filter carrying such an SCR catalyst may be referred to as SCRF.
- the size of the exhaust gas purification device can be made smaller than when the filter and the SCR catalyst are separately provided in the exhaust passage. Therefore, the mountability of the exhaust purification device can be improved. Further, by adopting SCRF, it becomes possible to arrange the SCR catalyst upstream of the exhaust passage. The more upstream the SCR catalyst is arranged in the exhaust passage, the more easily the SCR catalyst is heated by the heat of the exhaust. Therefore, it is possible to improve the warm-up property of the SCR catalyst and improve the NOx purification rate (the ratio of the NOx amount reduced in the SCR catalyst to the NOx amount flowing into the SCRF) in the SCR catalyst.
- Patent Document 1 discloses a configuration in which an oxidation catalyst, an injector, an SCRF, and a slip oxidation catalyst are sequentially provided from the upstream side along the flow of exhaust gas in an exhaust passage of a diesel engine.
- An injector is a device that injects ammonia or a precursor of ammonia into the exhaust.
- the slip oxidation catalyst is a catalyst that oxidizes ammonia that has passed through the SCRF.
- the filter regeneration process is a process for oxidizing and depositing PM deposited on the SCRF.
- the filter regeneration process is realized by supplying fuel to a pre-stage catalyst having an oxidation function provided in an exhaust passage upstream of SCRF.
- the exhaust gas flowing into the SCRF is heated by the oxidation heat. Therefore, the temperature of SCRF can be raised to the filter regeneration temperature at which PM oxidation is promoted.
- Patent Document 2 discloses a technique for reducing the amount of ammonia supplied to the SCRF before heat regeneration (filter regeneration) of the SCRF. According to this, the amount of ammonia adsorbed on the SCR catalyst can be reduced before the thermal regeneration of the SCRF. As a result, it is possible to suppress the release of ammonia accompanying the thermal regeneration of SCRF.
- Patent Document 3 estimates the amount of HC attached to the SCR catalyst provided in the exhaust passage, and raises the temperature of the SCR catalyst when the amount of HC attached exceeds the allowable amount of attachment.
- a technique for desorbing HC is disclosed.
- Patent Document 2 discloses a technique for stopping the temperature increase of the SCR catalyst when the amount of HC adhering to the SCR catalyst decreases to a predetermined lower limit after the temperature increase of the SCR catalyst is started.
- SCRF is supplied with ammonia or an ammonia precursor. Then, in the SCR catalyst carried on the SCRF, NOx in the exhaust is reduced using ammonia as a reducing agent.
- ammonia when ammonia is oxidized, NOx may be generated. Since it is necessary to suppress the generation of such NOx, it is difficult to carry a catalyst having a high oxidation ability on SCRF. Therefore, the SCR catalyst supported on SCRF has very low oxidation ability.
- a part of the HC contained in the fuel supplied to the pre-stage catalyst may pass through the pre-stage catalyst without being oxidized in the pre-stage catalyst.
- HC that has passed through the front catalyst flows into SCRF.
- the SCR catalyst supported on SCRF has a very low oxidation ability. Therefore, when HC flows into SCRF, a part of the HC adheres to SCRF. Then, there is a possibility that the attached HC is not oxidized but remains attached to the SCRF.
- the ammonia adsorption site to which ammonia should be adsorbed in the SCR catalyst supported on the SCRF is blocked by the HC.
- the ammonia adsorption site is blocked by HC, it becomes difficult for ammonia to be adsorbed on the SCR catalyst after the completion of the filter regeneration process. As a result, the NOx purification rate in the SCR catalyst decreases.
- the present invention has been made in view of the above problems, and an object of the present invention is to suppress a decrease in the NOx purification rate accompanying the execution of the filter regeneration process in an exhaust gas purification system for an internal combustion engine equipped with an SCRF.
- the temperature of the SCRF is raised by raising the temperature of the exhaust gas discharged from the internal combustion engine, thereby removing HC adhering to the SCRF.
- the exhaust gas purification system for an internal combustion engine is: A pre-stage catalyst provided in the exhaust passage of the internal combustion engine and having an oxidation function; A fuel supply device for supplying fuel to the upstream catalyst; A filter that is provided in an exhaust passage downstream of the preceding catalyst and collects particulate matter in exhaust gas, and carries a selective reduction type NOx catalyst that reduces NOx in exhaust gas using ammonia as a reducing agent.
- SCRF An ammonia supply device for supplying ammonia or an ammonia precursor to the filter
- a filter regeneration process execution unit for performing a filter regeneration process for increasing the temperature of the filter by supplying fuel from the fuel supply device to the upstream catalyst, thereby removing particulate matter deposited on the filter; After the completion of the filter regeneration process by the filter regeneration process execution unit, the temperature of the filter is raised by raising the temperature of the exhaust discharged from the internal combustion engine, thereby removing the HC adhering to the filter.
- An HC poisoning recovery process execution unit that executes a poison recovery process.
- the temperature of the SCRF When the temperature of the SCRF is raised by raising the temperature of the exhaust gas discharged from the internal combustion engine, the temperature of the SCRF can be raised while suppressing an increase in the amount of HC flowing into the SCRF. Therefore, by executing the HC poisoning recovery process after the completion of the filter regeneration process, it is possible to remove HC adhering to the SCRF by executing the filter regeneration process while suppressing the attachment of new HC to the SCRF. it can.
- the HC poisoning recovery process may be executed for a time corresponding to the amount of HC adhering to the SCRF at the start of execution of the HC poisoning recovery process.
- the HC poisoning recovery process may be executed for a time corresponding to the execution time of the filter regeneration process. According to these, it is possible to suppress the HC poisoning recovery processing from being excessively long while sufficiently removing the HC adhering to the SCRF.
- ammonia or an ammonia precursor in an amount corresponding to the SCRF temperature may be supplied to the SCRF by the ammonia supply device until the SCRF temperature reaches the target temperature during the filter regeneration process.
- ammonia can be adsorbed on the ammonia adsorption site in the SCR catalyst even during the time that the SCRF temperature reaches the target temperature during the execution of the filter regeneration process. Therefore, the amount of HC adsorbed on the SCRF during the filter regeneration process can be suppressed. Therefore, the execution time of the HC poisoning recovery process can be shortened.
- the present invention in the exhaust gas purification system for an internal combustion engine equipped with SCRF, it is possible to suppress a decrease in the NOx purification rate accompanying the execution of the filter regeneration process.
- FIG. 1 is a diagram illustrating a schematic configuration of an intake / exhaust system of an internal combustion engine according to Embodiment 1.
- FIG. 3 is a flowchart illustrating a flow of filter regeneration processing and HC poisoning recovery processing according to the first embodiment.
- SCRF temperature Tf, pre-catalyst temperature Tpc, fuel addition amount Fadd from the fuel addition valve, post-injection amount Fpost in the internal combustion engine, SCRF when the filter regeneration process and the HC poisoning recovery process according to the first embodiment are executed 6 is a time chart showing transitions of the HC adhesion amount Qhc, the ammonia gas addition amount Aadd from the ammonia addition valve, and the ammonia adsorption amount Qam on the SCR catalyst.
- 6 is a flowchart showing a flow of filter regeneration processing and HC poisoning recovery processing according to a modification of the first embodiment.
- 12 is a flowchart illustrating a flow of ammonia gas addition control during the execution of the filter regeneration process according to the second embodiment.
- SCRF temperature Tf, pre-catalyst catalyst temperature Tpc, fuel addition amount Fadd from the fuel addition valve, post-injection amount Fpost in the internal combustion engine, SCRF when the filter regeneration process and the HC poisoning recovery process according to the second embodiment are executed 6 is a time chart showing transitions of the HC adhesion amount Qhc, the ammonia gas addition amount Aadd from the ammonia addition valve, and the ammonia adsorption amount Qam on the SCR catalyst.
- Example 1 Here, the case where the exhaust gas purification system for an internal combustion engine according to the present invention is applied to a diesel engine for driving a vehicle will be described.
- the internal combustion engine according to the present invention is not limited to a diesel engine, and may be a gasoline engine or the like.
- FIG. 1 is a diagram showing a schematic configuration of an intake / exhaust system of an internal combustion engine according to the present embodiment.
- the internal combustion engine 1 is a diesel engine for driving a vehicle.
- An intake passage 2 and an exhaust passage 3 are connected to the internal combustion engine 1.
- An air flow meter 11 is provided in the intake passage 2. The air flow meter 11 detects the intake air amount of the internal combustion engine 1.
- a first exhaust temperature sensor 12 In the exhaust passage 3, a first exhaust temperature sensor 12, a fuel addition valve 4, a front catalyst 5, an ammonia addition valve 6, SCRF 7, a second exhaust temperature sensor 13, a rear catalyst 8, and a third exhaust temperature sensor 14 are exhausted. It is provided in order from the upstream side along the flow.
- the pre-stage catalyst 5 is an oxidation catalyst. However, the pre-stage catalyst 5 may be a catalyst other than the oxidation catalyst as long as it has an oxidation function.
- the fuel addition valve 4 adds fuel into the exhaust gas in order to supply fuel to the front catalyst 5.
- the fuel addition valve 4 corresponds to the fuel supply apparatus according to the present invention.
- the timing is later than the main fuel injection, and the injected fuel is not burned in the combustion chamber and is not burned in the exhaust passage 3.
- SCRF7 is configured by supporting an SCR catalyst 7a on a wall flow type filter that collects PM in exhaust gas.
- the SCR catalyst 7a reduces NOx in the exhaust gas using ammonia as a reducing agent.
- the ammonia addition valve 6 adds ammonia gas into the exhaust gas so as to supply ammonia to the SCRF 7.
- ammonia is supplied to the SCRF 7, the ammonia is once adsorbed at an ammonia adsorption site in the SCR catalyst 7a supported on the SCRF 7. Then, the adsorbed ammonia becomes a reducing agent, and NOx in the exhaust is reduced.
- the ammonia addition valve 6 corresponds to the ammonia supply device according to the present invention.
- the ammonia supply device according to the present invention may be a device that supplies ammonia as a liquid or a solid.
- the ammonia supply apparatus according to the present invention may be an apparatus for supplying an ammonia precursor.
- a urea addition valve for adding an aqueous urea solution into the exhaust gas may be provided instead of the ammonia addition valve 6, a urea addition valve for adding an aqueous urea solution into the exhaust gas may be provided. In this case, urea is supplied to SCRF 7 as an ammonia precursor. And ammonia is produced
- the latter stage catalyst 8 is an oxidation catalyst.
- the rear catalyst 8 may be another catalyst having an oxidation function.
- the rear catalyst 8 may be a catalyst configured by combining an oxidation catalyst and an SCR catalyst that reduces ammonia in exhaust using ammonia as a reducing agent.
- an oxidation catalyst is formed by supporting a noble metal such as platinum (Pt) on a support made of aluminum oxide (Al 2 O 3 ), zeolite, or the like, and copper (Cu SCR catalyst may be formed by supporting a base metal such as iron or iron (Fe).
- the rear catalyst 8 By making the rear catalyst 8 a catalyst having such a configuration, HC, CO and ammonia in the exhaust can be oxidized, and further, a part of ammonia is oxidized and NOx is generated and generated. NOx can be reduced using excess ammonia as a reducing agent.
- the first exhaust temperature sensor 12, the second exhaust temperature sensor 13, and the third exhaust temperature sensor 14 are sensors that detect the temperature of the exhaust.
- the first exhaust temperature sensor 12 detects the temperature of the exhaust discharged from the internal combustion engine 1.
- the second exhaust temperature sensor 13 detects the temperature of the exhaust gas flowing out from the SCRF 7.
- the third exhaust temperature sensor 14 detects the temperature of the exhaust gas flowing out from the rear catalyst 8.
- the internal combustion engine 1 is provided with an electronic control unit (ECU) 10.
- ECU electronice control unit
- Various sensors such as an air flow meter 11, a first exhaust temperature sensor 12, a second exhaust temperature sensor 13, and a third exhaust temperature sensor 14 are electrically connected to the ECU 10. And the output signal of various sensors is input into ECU10.
- the ECU 10 estimates the flow rate of the exhaust gas in the exhaust passage 3 based on the output value of the air flow meter 11. Further, the ECU 10 estimates the temperature of the SCRF 7 based on the output value of the second exhaust temperature sensor 13 and estimates the temperature of the rear catalyst 8 based on the output value of the third exhaust temperature sensor 14.
- the ECU 10 is electrically connected to the fuel injection valve, the fuel addition valve 4 and the ammonia addition valve 6 of the internal combustion engine 1. These devices are controlled by the ECU 10.
- the collected PM is gradually deposited on the SCRF 7. Therefore, in this embodiment, a filter regeneration process is executed to remove PM deposited on the SCRF 7.
- the filter regeneration process according to the present embodiment is realized by adding fuel from the fuel addition valve 4 and supplying the fuel to the front catalyst 5 thereby. When the fuel is oxidized in the front catalyst 5, oxidation heat is generated. The exhaust gas flowing into the SCRF 7 is heated by this oxidation heat. Thereby, the temperature of SCRF7 rises.
- the amount of fuel added from the fuel addition valve 4 is controlled to raise the temperature of the SCRF 7 to a predetermined filter regeneration temperature (for example, 650 ° C.) at which PM oxidation is promoted. As a result, PM deposited on SCRF 7 is oxidized and removed.
- a predetermined filter regeneration temperature for example, 650 ° C.
- the filter regeneration process is executed every time a predetermined time elapses.
- the filter regeneration process may be executed each time a vehicle equipped with the internal combustion engine 1 travels a predetermined travel distance. Further, the filter regeneration process may be executed every time the PM accumulation amount in SCRF 7 reaches a predetermined accumulation amount.
- the PM accumulation amount in the SCRF 7 can be estimated based on the history of the fuel injection amount in the internal combustion engine 1, the flow rate of the exhaust gas flowing into the SCRF 7, the temperature of the SCRF 7, and the like.
- a part of the HC contained in the fuel supplied to the front catalyst 5 may pass through the front catalyst 5 without being oxidized in the front catalyst 5.
- HC that has passed through the front catalyst 5 flows into the SCRF 7.
- the SCR catalyst 7a supported on the SCRF 7 has a very low oxidizing ability. Therefore, when HC flows into SCRF7, a part of the HC adheres to SCRF7. Then, there is a possibility that the attached HC is not oxidized but remains attached to the SCRF.
- the ammonia adsorption site to which ammonia should be adsorbed in the SCR catalyst 7a supported on the SCRF 7 is blocked by the HC.
- the HC poisoning recovery process is executed to remove the HC adhering to the SCRF 7.
- the HC poisoning recovery process is a process of increasing the temperature of the SCRF 7 to an HC poisoning recovery temperature (for example, 650 ° C.) at which HC oxidation is promoted by increasing the temperature of the exhaust gas discharged from the internal combustion engine 1.
- This HC poisoning recovery process is realized in the internal combustion engine 1 by executing the auxiliary fuel injection at a timing later than the main fuel injection and when the injected fuel is used for combustion in the combustion chamber. The By executing the auxiliary fuel injection at such timing, the temperature of the exhaust gas discharged from the internal combustion engine 1 can be raised.
- the auxiliary fuel injection executed at such timing is referred to as post injection.
- the temperature of the SCRF 7 When the temperature of the SCRF 7 is increased by increasing the temperature of the exhaust gas discharged from the internal combustion engine 1, the temperature of the SCRF 7 can be increased while suppressing an increase in the amount of HC flowing into the SCRF 7. Therefore, by executing the HC poisoning recovery process after the completion of the filter regeneration process, it is possible to remove the HC adhering to the SCRF 7 by executing the filter regeneration process while suppressing the adhesion of new HC to the SCRF 7. it can.
- FIG. 2 is a flowchart showing the flow of the filter regeneration process and the HC poisoning recovery process according to this embodiment. This flow is stored in advance in the ECU 10 and is repeatedly executed by the ECU 10.
- step S101 it is determined whether or not an execution condition for the filter regeneration process is satisfied. In this embodiment, when a predetermined time has elapsed since the previous execution of the filter regeneration process has been completed, it is determined that the condition for executing the filter regeneration process has been satisfied. If a negative determination is made in step S101, the execution of this flow is temporarily terminated. On the other hand, when an affirmative determination is made in step S101, the process of step S102 is executed next.
- step S102 fuel addition from the fuel addition valve 4 is executed. That is, the filter regeneration process is executed.
- the temperature of the SCRF 7 is adjusted to the filter regeneration temperature, which is the target temperature, by controlling the amount of fuel added from the fuel addition valve 4.
- step S103 it is determined whether or not an execution end condition for the filter regeneration process is satisfied.
- a predetermined regeneration execution time has elapsed since the start of the execution of the filter regeneration process, it is determined that the execution end condition for the filter regeneration process is satisfied.
- step S103 If a negative determination is made in step S103, the processes in steps S102 and S103 are executed again. On the other hand, when a positive determination is made in step S103, the process of step S104 is performed next. In step S104, the fuel addition from the fuel addition valve 4 is stopped. That is, the execution of the filter regeneration process is terminated.
- step S105 the HC adhesion amount Qhc at the current SCRF 7 is calculated.
- the amount of HC adhering to the SCRF 7 per unit time and the amount of HC oxidized per unit time during execution of the filter regeneration process are the amount of fuel added from the fuel addition valve 4, the flow rate of exhaust, the temperature of the pre-stage catalyst 5, and It can be estimated based on the temperature of the SCRF 7 or the like. Then, by accumulating these values, the HC adhesion amount Qhc in SCRF 7 can be calculated.
- step S106 an execution time ⁇ Tp of the HC poisoning recovery process to be executed is set.
- the execution time ⁇ Tp of the HC poisoning recovery process is set based on the HC adhesion amount Qhc in SCRF7. That is, when the HC adhesion amount Qhc in SCRF 7 is large, the execution time ⁇ Tp of the HC poisoning recovery process is set shorter than when the HC adhesion amount Qhc is small.
- the relationship between the HC adhesion amount Qhc in SCRF 7 and the execution time ⁇ Tp of the HC poisoning recovery process is determined based on experiments and the like. The relationship between these values is stored in advance in the ECU 10 as a map or a function.
- step S107 post injection in the internal combustion engine 1 is executed. That is, the HC poisoning recovery process is executed.
- the temperature of the SCRF 7 is adjusted to the HC poisoning recovery temperature, which is the target temperature, by controlling the injection timing and the injection amount of the auxiliary fuel injection.
- the HC poisoning recovery temperature and the filter regeneration temperature may be the same temperature.
- step S108 whether or not the time ⁇ Tp set in step S106 has elapsed since the start of the post injection in the internal combustion engine 1, that is, the start of the HC poisoning recovery process. Determined. If a negative determination is made in step S108, the processes in steps S107 and S108 are executed again. On the other hand, if an affirmative determination is made in step S108, the process of step S109 is then executed. In step S109, the post injection is stopped. That is, the execution of the HC poisoning recovery process is terminated.
- the execution time ⁇ Tp of the HC poisoning recovery process is set based on the HC adhesion amount Qhc in SCRF7.
- the HC poisoning recovery process may be executed without setting the execution time of the HC poisoning recovery process in advance.
- the residual amount of HC in SCRF 7 is estimated during the execution of the HC poisoning recovery process.
- the execution of the HC poisoning recovery process may be terminated when the estimated residual HC amount is equal to or less than the predetermined residual amount.
- the amount of HC oxidation per unit time during execution of the HC poisoning recovery process can be estimated based on the flow rate of the exhaust gas, the temperature of the SCRF 7, and the like.
- the HC residual amount in SCRF 7 can be calculated by subtracting the HC oxidation amount from the HC adhesion amount at the start of execution of the HC poisoning recovery process.
- the execution time of the HC poisoning recovery process may be set based on the execution time of the filter regeneration process. In this case, when the execution time of the filter regeneration process is short, the execution time of the HC poisoning recovery process is set shorter than when the execution time of the filter regeneration process is long. Also by this, it is possible to suppress excessively long execution time of the HC poisoning recovery process while sufficiently removing the HC adhering to the SCRF 7.
- the execution time of the HC poisoning recovery process may be a predetermined time. Even in this case, the HC adhering to the SCRF 7 can be removed by executing the filter regeneration process. However, from the viewpoint of suppressing deterioration in fuel consumption, it is preferable to change the execution time of the HC poisoning recovery process according to the HC adhesion amount in SCRF 7 or the execution time of the filter regeneration process as described above.
- the PM residual amount in SCRF 7 may be estimated during the filter regeneration process. Then, in step S103 of the above flow, when the estimated PM residual amount becomes equal to or smaller than the predetermined residual amount, it may be determined that the condition for ending the filter regeneration process is satisfied.
- the amount of PM oxidation per unit time during the execution of the filter regeneration process can be estimated based on the exhaust flow rate, the temperature of the SCRF 7, and the like. Then, the PM residual amount in SCRF 7 can be calculated by subtracting the PM oxidation amount from the PM deposition amount at the start of execution of the filter regeneration process.
- the predetermined residual amount may be an amount larger than an amount at which it can be determined that substantially all of the oxidizable PM has been removed.
- the temperature of the SCRF 7 is adjusted to a target temperature substantially the same as the target temperature in the filter regeneration process even during the execution of the HC poisoning recovery process. Therefore, even if PM remains in the SCRF 7 when the filter regeneration process is completed, the remaining PM can be oxidized and removed during the execution of the HC poisoning recovery process.
- FIG. 3 shows the temperature Tf of the SCRF 7, the temperature Tpc of the front catalyst 5, the fuel addition amount Fadd from the fuel addition valve 4, the internal combustion engine 1 when the filter regeneration process and the HC poisoning recovery process according to this embodiment are executed.
- 6 is a time chart showing changes in post injection amount Fpost at HC, HC adhesion amount Qhc at SCRF7, ammonia gas addition amount Aadd from the ammonia addition valve 6, and ammonia adsorption amount Qam at the SCR catalyst 7a.
- the horizontal axis represents time t.
- Tft represents the target temperature (filter regeneration temperature, HC poisoning recovery temperature) of SCRF 7 in the filter regeneration process and the HC poisoning recovery process.
- the fuel addition from the fuel addition valve 4 is executed from time t0 to time t3. That is, the execution time of the filter regeneration process is from time t0 to t3. Therefore, during the period from time t0 to t3, the HC attachment amount Qhc in SCRF7 increases. During this time, the temperature Tf of the SCRF 7 gradually increases from the time t1 to the time t2, and the SCRF temperature Tf is maintained at the target temperature (filter regeneration temperature) Tft from the time t2 to the time t3.
- the period from time t3 to t4 is the execution time of the HC poisoning recovery process.
- the supply of new HC to the SCRF 7 is suppressed, and the temperature Tf of the SCRF 7 is maintained at the target temperature (HC poisoning recovery temperature). Therefore, during the period from time t3 to t4, the HC adhesion amount Qhc in SCRF7 decreases.
- the temperature Tf of the SCRF 7 reaches the target temperature (filter regeneration temperature, HC poisoning recovery temperature) Tft, it is difficult for ammonia to be adsorbed on the SCR catalyst 7a. Therefore, in the present embodiment, the addition of ammonia gas from the ammonia addition valve 6 is stopped during the execution of the filter regeneration process and the HC poisoning recovery process.
- the temperature Tf of SCRF 7 (that is, the temperature of the SCR catalyst 7a) gradually decreases between time t4 and time t5. Accordingly, the amount of ammonia that can be adsorbed on the SCR catalyst 7a increases. Therefore, during the time t4 to t5, the ammonia gas addition amount Aadd from the ammonia addition valve 6 is gradually increased. Thereby, during the time t4 to t5, the ammonia adsorption amount Qam in the SCR catalyst 7a gradually increases.
- FIG. 4 is a flowchart showing the flow of filter regeneration processing and HC poisoning recovery processing according to this modification.
- processes other than step S205 are the same as those in the flowchart shown in FIG. Therefore, only the process of step S205 will be described, and the description of the process of other steps will be omitted.
- This flow is stored in advance in the ECU 10 and is repeatedly executed by the ECU 10.
- step S205 it is determined whether or not the temperature of SCRF 7 has become equal to or lower than a predetermined processing start temperature Tf0.
- the processing start temperature Tf0 is a temperature that is equal to or lower than a target temperature (filtering temperature) for the filter regeneration processing and is equal to or higher than a lower limit value of the temperature at which HC attached to the SCRF 7 can be oxidized.
- This processing start temperature Tf0 is determined in advance based on experiments and the like.
- step S104 If a negative determination is made in step S104, the process of step S104 is executed again. On the other hand, if an affirmative determination is made in step S104, the process of step S105 is then executed.
- step S105 the amount of HC deposited in SCRF 7 at the current time is subtracted from the amount of HC deposited in SCRF 7 at the end of execution of the filter regeneration process to subtract the amount of HC oxidized after the completion of execution of the filter regeneration process. Is calculated.
- the execution time ⁇ Tp of the HC poisoning recovery process set in step S106 can be shortened. As a result, it becomes possible to further suppress the deterioration of fuel consumption accompanying the execution of the HC poisoning recovery process.
- Example 2 The schematic configuration of the intake and exhaust system of the internal combustion engine according to the present embodiment is the same as that according to the first embodiment. Hereinafter, only differences from the first embodiment in the filter regeneration process and the HC poisoning recovery process according to the present embodiment will be described.
- Example 1 As described above, when the temperature of the SCRF 7 rises to the target temperature (filter regeneration temperature, HC poisoning recovery temperature), it is difficult for ammonia to be adsorbed on the SCR catalyst 7a. Therefore, in Example 1, the addition of ammonia gas from the ammonia addition valve 6 was stopped during the execution of the filter regeneration process and the HC poisoning recovery process. However, ammonia can be adsorbed on the SCR catalyst 7a until the temperature of the SCRF 7 reaches the target temperature during the filter regeneration process, that is, while the temperature of the SCRF 7 is lower than the target temperature. Therefore, in this embodiment, addition of ammonia gas from the ammonia addition valve 6 is executed until the temperature of the SCRF 7 reaches the target temperature even during execution of the filter regeneration process.
- ammonia can be adsorbed on the ammonia adsorption sites in the SCR catalyst 7a even during the time until the temperature of the SCRF 7 reaches the target temperature during execution of the filter regeneration process. Therefore, the amount of HC adhering to SCRF 7 during the filter regeneration process can be suppressed. As a result, the amount of HC adhering to SCRF 7 at the end of execution of the filter regeneration process can be reduced.
- FIG. 5 is a flowchart showing a flow of ammonia gas addition control during the execution of the filter regeneration process according to the present embodiment. This flow is stored in advance in the ECU 10 and is repeatedly executed by the ECU 10.
- step S301 it is determined whether or not the filter regeneration process is being executed. If a negative determination is made in step S301, the execution of this flow is temporarily terminated. On the other hand, if an affirmative determination is made in step S301, the process of step S302 is then executed.
- step S302 it is determined whether or not the temperature Tf of the SCRF 7 is lower than the target temperature Tft (filter regeneration temperature) Tft. If an affirmative determination is made in step S302, then the process of step S303 is executed.
- step S303 an ammonia gas addition amount Add from the ammonia addition valve 6 is set.
- the ammonia gas addition amount Add is set according to the temperature Tf of SCRF 7 (that is, the temperature of SCR catalyst 7a). That is, when the temperature Tf of the SCRF 7 is high, the ammonia addition amount Add is set smaller than when the temperature is low.
- the relationship between the ammonia addition amount Add and the temperature Tf of the SCRF 7 is determined based on experiments and the like. The relationship between these values is stored in advance in the ECU 10 as a map or a function.
- step S304 addition of ammonia from the ammonia addition valve 6 is executed. At this time, the amount of ammonia added is adjusted to the amount set in step S303.
- step S302 determines whether the temperature of SCRF 7 has reached the target temperature Tft. If a negative determination is made in step S302, that is, if the temperature of SCRF 7 has reached the target temperature Tft, the process of step S305 is then executed. In step S305, the addition of ammonia gas from the ammonia addition valve 6 is stopped.
- the amount of ammonia gas added from the ammonia addition valve 6 gradually increases as the temperature of the SCRF 7 rises. Reduced to Thereby, it can suppress that an excessive amount of ammonia gas is supplied to SCRF7. Therefore, the ammonia outflow from SCRF 7 can be suppressed.
- FIG. 6 shows the temperature Tf of the SCRF 7, the temperature Tpc of the front catalyst 5, the fuel addition amount Fadd from the fuel addition valve 4, the internal combustion engine 1 when the filter regeneration process and the HC poisoning recovery process according to this embodiment are executed.
- 6 is a time chart showing changes in post injection amount Fpost at HC, HC adhesion amount Qhc at SCRF7, ammonia gas addition amount Aadd from the ammonia addition valve 6, and ammonia adsorption amount Qam at the SCR catalyst 7a.
- the horizontal axis represents time t.
- Tft represents the target temperature (filter regeneration temperature, HC poisoning recovery temperature) of SCRF 7 in the filter regeneration process and the HC poisoning recovery process.
- the solid line indicates the transition of each value according to the present embodiment, and the broken line indicates the transition of each value when the filter regeneration process and the HC poisoning recovery process according to the first embodiment are performed. Show.
- the addition of ammonia gas from the ammonia addition valve 6 is also executed during the time t0 to t2 during which the filter regeneration process is being executed. Then, during the time t1 to t2, the amount of ammonia gas added from the ammonia addition valve 6 is gradually reduced as the temperature of the SCRF 7 rises. As a result, at the time t2, the ammonia adsorption amount Qam in the SCR catalyst 7a becomes substantially zero.
- the execution time of the HC poisoning recovery process (time from t3 to t4) can be shortened compared to the case of the first embodiment.
- the SCRF 7 rises to a temperature at which PM oxidation is promoted, as in the filter regeneration process.
- the temperature of the SCRF 7 is set to the same temperature by supplying fuel to the upstream catalyst 5. Compared with the case where the fuel consumption is increased up to, the fuel consumption is increased. Therefore, removal of PM deposited on SCRF 7 is performed by filter regeneration processing in order to suppress deterioration of fuel consumption.
Abstract
Description
内燃機関の排気通路に設けられ、酸化機能を有する前段触媒と、
前記前段触媒に燃料を供給する燃料供給装置と、
前記前段触媒より下流側の排気通路に設けられ、排気中の粒子状物質を捕集するフィルタであって、アンモニアを還元剤として排気中のNOxを還元する選択還元型NOx触媒が担持されたフィルタ(SCRF)と、
前記フィルタにアンモニア又はアンモニアの前駆体を供給するアンモニア供給装置と、
前記燃料供給装置から前記前段触媒に燃料を供給することで前記フィルタの温度を上昇させ、それによって前記フィルタに堆積した粒子状物質を除去するフィルタ再生処理を実行するフィルタ再生処理実行部と、
前記フィルタ再生処理実行部によるフィルタ再生処理の実行終了後、内燃機関から排出される排気の温度を上昇させることで前記フィルタの温度を上昇させ、それによって前記フィルタに付着したHCを除去するHC被毒回復処理を実行するHC被毒回復処理実行部と、を備える。
ここでは、本発明に係る内燃機関の排気浄化システムを、車両駆動用のディーゼルエンジンに適用した場合について説明する。ただし、本発明に係る内燃機関は、ディーゼルエンジンに限られるものではなく、ガソリンエンジン等であってもよい。
図1は、本実施例に係る内燃機関の吸排気系の概略構成を示す図である。内燃機関1は車両駆動用のディーゼルエンジンである。内燃機関1には吸気通路2及び排気通路3が接続されている。吸気通路2にはエアフローメータ11が設けられている。エアフローメータ11は内燃機関1の吸入空気量を検知する。
SCRF7には、捕集されたPMが徐々に堆積する。そこで、本実施例においては、SCRF7に堆積したPMを除去するためにフィルタ再生処理が実行される。本実施例に係るフィルタ再生処理は、燃料添加弁4から燃料を添加し、それによって燃料を前段触媒5に供給することで実現される。前段触媒5において燃料が酸化されると酸化熱が生じる。この酸化熱によってSCRF7に流入する排気が加熱される。これにより、SCRF7の温度が上昇する。フィルタ再生処理の実行時においては、燃料添加弁4からの燃料添加量を制御することで、SCRF7の温度をPMの酸化が促進される所定のフィルタ再生温度(例えば、650℃)まで上昇させる。その結果、SCRF7に堆積したPMが酸化され除去される。
図2は、本実施例に係るフィルタ再生処理及びHC被毒回復処理のフローを示すフローチャートである。本フローはECU10に予め記憶されており、ECU10によって繰り返し実行される。
図3は、本実施例に係るフィルタ再生処理及びHC被毒回復処理を実行した際の、SCRF7の温度Tf、前段触媒5の温度Tpc、燃料添加弁4からの燃料添加量Fadd、内燃機関1におけるポスト噴射量Fpost、SCRF7におけるHC付着量Qhc、アンモニア添加弁6からのアンモニアガス添加量Aadd、及びSCR触媒7aにおけるアンモニア吸着量Qamの推移を示すタイムチャートである。図3において、横軸が時間tを表している。また、図3において、Tftが、フィルタ再生処理及びHC被毒回復処理におけるSCRF7の目標温度(フィルタ再生温度、HC被毒回復温度)を表している。
次に、本実施例の変形例について説明する。本実施例において、フィルタ再生処理の実行終了後、即ち燃料添加弁4からの燃料添加の停止後、HC被毒回復処理を実行しなくてもSCRF7の温度がHCの酸化が可能な温度に維持されていれば、SCRF7に付着したHCは除去される。そのため、必ずしも、フィルタ再生処理の実行終了と同時にHC被毒回復処理の実行を開始する必要はない。
本実施例に係る内燃機関の吸排気系の概略構成は実施例1に係る構成と同様である。以下、本実施例に係るフィルタ再生処理及びHC被毒回復処理において、実施例1と異なる点についてのみ説明する。
図5は、本実施例に係るフィルタ再生処理の実行中におけるアンモニアガス添加制御のフローを示すフローチャートである。本フローはECU10に予め記憶されており、ECU10によって繰り返し実行される。
設定された量に調整される。
図6は、本実施例に係るフィルタ再生処理及びHC被毒回復処理を実行した際の、SCRF7の温度Tf、前段触媒5の温度Tpc、燃料添加弁4からの燃料添加量Fadd、内燃機関1におけるポスト噴射量Fpost、SCRF7におけるHC付着量Qhc、アンモニア添加弁6からのアンモニアガス添加量Aadd、及びSCR触媒7aにおけるアンモニア吸着量Qamの推移を示すタイムチャートである。図6において、横軸が時間tを表している。また、図6において、Tftが、フィルタ再生処理及びHC被毒回復処理におけるSCRF7の目標温度(フィルタ再生温度、HC被毒回復温度)を表している。また、図6において、実線は、本実施例に係る各値の推移を示しており、破線は、実施例1に係るフィルタ再生処理及びHC被毒回復処理を実行した際の各値の推移を示している。
2・・・吸気通路
3・・・排気通路
4・・・燃料添加弁
5・・・前段触媒
6・・・アンモニア添加弁
7・・・フィルタ(SCRF)
7a・・選択還元型NOx触媒(SCR触媒)
8・・・後段触媒
10・・ECU
11・・エアフローメータ
12・・第1排気温度センサ
13・・第2排気温度センサ
14・・第3排気温度センサ
Claims (4)
- 内燃機関の排気通路に設けられ、酸化機能を有する前段触媒と、
前記前段触媒に燃料を供給する燃料供給装置と、
前記前段触媒より下流側の排気通路に設けられ、排気中の粒子状物質を捕集するフィルタであって、アンモニアを還元剤として排気中のNOxを還元する選択還元型NOx触媒が担持されたフィルタと、
前記フィルタにアンモニア又はアンモニアの前駆体を供給するアンモニア供給装置と、
前記燃料供給装置から前記前段触媒に燃料を供給することで前記フィルタの温度を上昇させ、それによって前記フィルタに堆積した粒子状物質を除去するフィルタ再生処理を実行するフィルタ再生処理実行部と、
前記フィルタ再生処理実行部によるフィルタ再生処理の実行終了後、内燃機関から排出される排気の温度を上昇させることで前記フィルタの温度を上昇させ、それによって前記フィルタに付着したHCを除去するHC被毒回復処理を実行するHC被毒回復処理実行部と、を備える内燃機関の排気浄化システム。 - HC被毒回復処理が、該HC被毒回復処理の実行開始時の前記フィルタにおけるHC付着量に応じた時間実行される請求項1に記載の内燃機関の排気浄化システム。
- HC被毒回復処理が、フィルタ再生処理の実行時間に応じた時間実行される請求項1に記載の内燃機関の排気浄化システム。
- フィルタ再生処理の実行中において前記フィルタの温度が目標温度に達するまでの間、前記フィルタの温度に応じた量のアンモニア又はアンモニアの前駆体を前記アンモニア供給装置によって前記フィルタに供給する請求項1から3のいずれか一項に記載の内燃機関の排気浄化システム。
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- 2012-12-26 EP EP12891274.8A patent/EP2940265A4/en not_active Withdrawn
- 2012-12-26 CN CN201280078001.7A patent/CN104870767A/zh active Pending
- 2012-12-26 JP JP2014553938A patent/JPWO2014102932A1/ja active Pending
- 2012-12-26 US US14/655,586 patent/US20150330275A1/en not_active Abandoned
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Cited By (7)
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WO2016103627A1 (en) * | 2014-12-24 | 2016-06-30 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purification system for an internal combustion engine |
JP2016121589A (ja) * | 2014-12-24 | 2016-07-07 | トヨタ自動車株式会社 | 内燃機関の排気浄化システム |
CN107109983A (zh) * | 2014-12-24 | 2017-08-29 | 丰田自动车株式会社 | 用于内燃发动机的排气净化系统 |
CN107109983B (zh) * | 2014-12-24 | 2019-05-17 | 丰田自动车株式会社 | 用于内燃发动机的排气净化系统 |
US10337376B2 (en) | 2014-12-24 | 2019-07-02 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purification system for an internal combustion engine |
JP2016176429A (ja) * | 2015-03-20 | 2016-10-06 | 三菱自動車工業株式会社 | エンジンの排気浄化装置 |
JP2017053334A (ja) * | 2015-09-11 | 2017-03-16 | トヨタ自動車株式会社 | 内燃機関の排気浄化システム |
Also Published As
Publication number | Publication date |
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JPWO2014102932A1 (ja) | 2017-01-12 |
CN104870767A (zh) | 2015-08-26 |
EP2940265A4 (en) | 2015-12-23 |
EP2940265A1 (en) | 2015-11-04 |
US20150330275A1 (en) | 2015-11-19 |
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