US20100005787A1 - Exhaust gas purification apparatus for engine - Google Patents
Exhaust gas purification apparatus for engine Download PDFInfo
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- US20100005787A1 US20100005787A1 US12/441,412 US44141207A US2010005787A1 US 20100005787 A1 US20100005787 A1 US 20100005787A1 US 44141207 A US44141207 A US 44141207A US 2010005787 A1 US2010005787 A1 US 2010005787A1
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- exhaust gas
- selective reduction
- temperature
- reduction catalyst
- fuel
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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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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/9459—Removing one or more of nitrogen oxides, carbon monoxide, or hydrocarbons by multiple successive catalytic functions; systems with more than one different function, e.g. zone coated catalysts
- B01D53/9477—Removing one or more of nitrogen oxides, carbon monoxide, or hydrocarbons by multiple successive catalytic functions; systems with more than one different function, e.g. zone coated catalysts with catalysts positioned on separate bricks, e.g. exhaust systems
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/9495—Controlling the catalytic process
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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
- F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
- F01N11/002—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
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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
- 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
- F01N13/0093—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 the purifying devices are of the same type
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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
- F01N13/0097—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 the purifying devices are arranged in a single housing
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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
- F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
- F01N3/2892—Exhaust flow directors or the like, e.g. upstream of catalytic device
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/20—Reductants
- B01D2251/206—Ammonium compounds
- B01D2251/2062—Ammonia
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/40—Nitrogen compounds
- B01D2257/406—Ammonia
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/9404—Removing only nitrogen compounds
- B01D53/9409—Nitrogen oxides
- B01D53/9413—Processes characterised by a specific catalyst
- B01D53/9418—Processes characterised by a specific catalyst for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of 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
- 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
- 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
- F02B29/0425—Air cooled heat exchangers
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- 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
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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
- F02D41/024—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
- F02D41/025—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 changing the composition of the exhaust gas, e.g. for exothermic reaction on exhaust gas treating apparatus
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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
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
- F02D41/1446—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being exhaust temperatures
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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
- F02D41/30—Controlling fuel injection
- F02D41/38—Controlling fuel injection of the high pressure type
- F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
- F02D41/402—Multiple injections
- F02D41/405—Multiple injections with post injections
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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 apparatus for an engine, which removes nitrogen oxides contained in exhaust gas of a diesel engine to purify the exhaust gas.
- an exhaust gas purification apparatus for reducing nitrogen oxides (hereinafter abbreviated as NOx) contained in exhaust gas of a diesel engine there has been known an exhaust gas purification apparatus for a diesel engine, in which a selective reduction catalyst is provided midway in an exhaust passage of the diesel engine, and a liquid injection nozzle capable of injecting a urea-based liquid toward the selective reduction catalyst is provided in an exhaust pipe on the exhaust gas upstream side of the selective reduction catalyst.
- the urea-based liquid injected from the liquid injection nozzle is heated by the heat of exhaust gas and is hydrolyzed, by which ammonia is yielded.
- This ammonia functions as a reducing agent for reducing NOx in exhaust gas by using the selective reduction catalyst so that the quantity of NOx discharged to the atmosphere can be decreased.
- a mixer configured so that the liquid injected from the liquid injection nozzle can be mixed with exhaust gas is provided in an exhaust pipe between the liquid injection nozzle and the selective reduction catalyst (for example, refer to Japanese Unexamined Patent Application Publication No. 2003-232218 (“JP '218”) (Clams for the Patent, FIG. 1)
- ammonia yielded by the hydrolysis of urea-based liquid functions as a reducing agent only when the temperature of exhaust gas is relatively high.
- ammonia does not function as a reducing agent.
- the exhaust gas purification apparatus using the selective reduction catalyst in the exhaust pipe there remains an unsolved problem in that NOx in exhaust gas cannot be removed effectively when the temperature of exhaust gas is relatively low.
- An object of the present invention is to provide an exhaust gas purification apparatus for an engine capable of effectively removing NOx in exhaust gas even when the temperature of exhaust gas is relatively low.
- the invention is an improvement in an exhaust gas purification apparatus including, as shown in FIG. 1 , a selective reduction catalyst 21 provided in an exhaust pipe 16 of a diesel engine 11 driven by burning a fuel, which is injected from a fuel injection device, in a cylinder; a liquid injection nozzle 23 provided in the exhaust pipe 16 on the exhaust gas upstream side of the selective reduction catalyst 21 ; a liquid injecting means 30 capable of injecting a urea-based liquid 32 toward the selective reduction catalyst 21 via the liquid injection nozzle 23 ; a controller 44 for controlling the liquid injecting means 30 ; and a mixer 26 that is provided in the exhaust pipe 16 between the liquid injection nozzle 23 and the selective reduction catalyst 21 and is configured so that the liquid 32 injected from the liquid injection nozzle 23 is mixed with exhaust gas.
- the characteristic configuration of the above-described exhaust gas purification apparatus is that the apparatus further includes an ammonia purification catalyst 54 provided in the exhaust pipe 16 on the exhaust gas downstream side of the selective reduction catalyst 21 ; a diesel particulate filter 51 provided in the exhaust pipe 16 on the exhaust gas upstream side of the liquid injection nozzle 23 ; an oxidation catalyst 53 provided in the exhaust pipe 16 on the exhaust gas upstream side of the diesel particulate filter 51 ; and a temperature sensor 43 for detecting the temperature of the selective reduction catalyst 21 and sending the detected temperature to the controller 44 , the fuel injection device is configured so as to be capable of injecting the fuel into the cylinder after the top dead center of piston, and when the temperature sensor 43 detects that the selective reduction catalyst 21 has a temperature not higher than 170° C., the controller 44 controls the fuel injection device so that the fuel is injected into the cylinder after the top dead center of piston.
- the liquid 32 flows into the mixer 26 , being sufficiently mixed with exhaust gas, and reaches the selective reduction catalyst 21 uniformly.
- the selective reduction catalyst 21 the urea-based liquid 32 is heated by exhaust gas and is hydrolyzed, and ammonia yielded by the hydrolysis reduces NO and NO 2 , by which the emission of NOx is reduced.
- the ammonia purification catalyst 54 oxidizes ammonia passing through the selective reduction catalyst 21 without being used as a reducing agent, by which the ammonia is converted to harmless N 2 and H 2 O so that the ammonia is effectively prevented from being discharged to the atmosphere.
- the particulate filter 51 captures particulates in the exhaust gas of the diesel engine 11 , so that the particulates can be effectively prevented from being discharged to the outside.
- the invention is characterized further in that the fuel injection device is configured so as to be capable of injecting the fuel into a cylinder after the top dead center of piston; the temperature sensor 43 is provided at the inlet of the selective reduction catalyst 21 and is configured so as to be capable of measuring the temperature of exhaust gas flowing into the selective reduction catalyst 21 ; and when the temperature sensor 43 detects a temperature not higher than a predetermined temperature, the controller 44 controls the fuel injection device so that the fuel is injected into the cylinder after the top dead center of piston.
- the fuel burns in the exhaust pipe 16 , or undergoes oxidation reaction in the oxidation catalyst 53 provided on the upstream side of the particulate filter 51 to remarkably raise the temperature of exhaust gas, by which the temperature of the selective reduction catalyst 21 on the downstream side of the particulate filter 51 is increased rapidly.
- the controller 44 controls the fuel injection device so that the fuel is injected into the cylinder after the top dead center of piston. Thereby, the temperature of the selective reduction catalyst 21 is increased rapidly, and therefore NOx in exhaust gas can be removed effectively.
- the fuel is injected into the cylinder after the top dead center of piston by the fuel injection device, and the fuel is burned in the particulate filter 51 together with the particulates, by which the particulate filter 51 can be regenerated.
- the invention is characterized further in that a turbocharger 17 is provided on the engine 11 , and the oxidation catalyst 53 consists of a first oxidation catalyst 53 a provided in the exhaust pipe 16 just in rear of the turbocharger 17 and a second oxidation catalyst 53 b provided in the exhaust pipe 16 just in front of the diesel particulate filter 51 .
- the invention is characterized further in that the fuel injection device is configured so as to be capable of accomplishing both of after injection for injecting the fuel when the crank angle is in the range of 30 to 50 degrees after the top dead center of piston and post injection for injecting the fuel when the crank angle is in the range of 90 to 130 degrees after the top dead center of piston; and when the temperature sensor 43 detects that the selective reduction catalyst 21 has a temperature not higher than the predetermined temperature, the controller 44 controls the fuel injection device so that both of the after injection and the post injection are accomplished.
- the after injection can increase hydrocarbon in exhaust gas and burn the hydrocarbon to raise the temperature of exhaust gas flowing out of the engine 11 to the exhaust pipe 16 .
- the post injection can cause the hydrocarbon increased in exhaust gas to undergo oxidation reaction in the oxidation catalyst 53 provided on the upstream side of the particulate filter 51 to further raise the temperature of exhaust gas, by which the temperature of the selective reduction catalyst 21 can be increased rapidly.
- the liquid injection nozzle, the mixer, and the selective reduction catalyst are provided, when the urea-based liquid is injected from the injection nozzle, the urea-based liquid flows into the mixer, being mixed with exhaust gas, and reaches the selective reduction catalyst.
- the selective reduction catalyst the urea-based liquid is hydrolyzed, and ammonia yielded by the hydrolysis reduces NO and NO 2 , by which the emission of NOx is reduced.
- the ammonia purification catalyst provided in the exhaust pipe on the downstream side of the selective reduction catalyst oxidizes ammonia passing through the selective reduction catalyst without being used as a reducing agent, by which the ammonia is converted to harmless N 2 and H 2 O so that the ammonia is effectively prevented from being discharged to the atmosphere.
- the fuel when the fuel is injected into the cylinder after the top dead center of piston by the fuel injection device, the fuel burns in the exhaust pipe, or undergoes oxidation reaction in the oxidation catalyst provided on the upstream side of the particulate filter to remarkably raise the temperature of exhaust gas, by which the temperature of the selective reduction catalyst on the downstream side of the particulate filter is increased rapidly.
- the controller controls the fuel injection device so that the fuel is injected into the cylinder after the top dead center of piston. Thereby, the temperature of the selective reduction catalyst is increased rapidly, and therefore NOx in exhaust gas can be removed effectively.
- the particulate filter since the diesel particulate filter is provided in the exhaust pipe on the exhaust gas upstream side of the liquid injection nozzle, the particulate filter captures particulates in exhaust gas of the diesel engine to effectively prevent the particulates from being discharged to the outside. If the quantity of captured particulates increases, the resistance of exhaust gas passing through the particulate filter increases. However, by injecting the fuel into the cylinder after the top dead center of piston and by burning the fuel, the particulate filter can be regenerated.
- FIG. 1 is a general view showing a configuration of an exhaust gas purification apparatus in accordance with an embodiment of the present invention.
- FIG. 2 is a general view showing a configuration of an exhaust gas purification apparatus corresponding to the apparatus shown in FIG. 1 , which is provided with first and second oxidation catalysts.
- the intake port of a diesel engine 11 is connected with an intake pipe 13 via an intake manifold 12
- the exhaust port thereof is connected with an exhaust pipe 16 via an exhaust manifold 14
- the intake pipe 13 is provided with a compressor 17 a of a turbocharger 17 and an inter-cooler 18 for cooling intake air compressed by the turbocharger 17
- the exhaust pipe 16 is provided with a turbine 17 b of the turbocharger 17
- the rotary vane of the compressor 17 a and the rotary vane of the turbine 17 b are connected to each other by a shaft.
- the configuration is made such that the compressor 17 a is rotated via the turbine 17 b and the shaft by the energy of exhaust gas discharged from the engine 11 , by which intake air in the intake pipe 13 is compressed by the rotation of the compressor 17 a.
- a selective reduction catalyst 21 is provided in the middle of the exhaust pipe 16 .
- the catalyst 21 is accommodated in a cylindrical first converter 22 formed by enlarging the diameter of the exhaust pipe 16 .
- a copper zeolite catalyst which reduces NOx in exhaust gas flowing into the exhaust pipe 16 at a relatively low temperature of 200 to 300° C.
- a catalyst consisting of titanium oxide, vanadium oxide, or tungsten oxide may also be used.
- a liquid injection nozzle 23 capable of injecting a urea-based liquid 32 is provided so as to be directed toward the catalyst 21 , and in the exhaust pipe 16 between the liquid injection nozzle 23 and the selective reduction catalyst 21 , a mixer 26 configured so as to be capable of mixing the urea-based liquid 32 injected from the liquid injection nozzle 23 with exhaust gas is provided.
- the mixer 26 of this embodiment includes a mixer body 27 having a cylinder part 27 a through which exhaust gas passes in the axis line direction, and a plurality of partition plates 28 provided in the mixer body 27 .
- the mixer body 27 is manufactured by welding lid bodies 27 b and 27 c each formed by fabricating a stainless steel sheet into a funnel shape to both ends of the cylinder part 27 a formed by fabricating a stainless steel sheet into a cylindrical shape. That is to say, one end part facing to the cylinder part 27 a of each of the lid bodies 27 b and 27 c is formed so as to have an outside diameter equal to that of the cylinder part 27 a and is welded to the cylinder part 27 a .
- each of the lid bodies 27 b and 27 c is formed so as to have a diameter corresponding to that of the exhaust pipe 16 , and to the outer periphery of the other end part, ring-shaped flange members 27 d , 27 e for connecting the lid body 27 b , 27 c to the exhaust pipe 16 are welded.
- the flange members 27 d , 27 e are formed with a plurality of mounting holes, and can be screw-mounted to mounted members 16 a , 16 b provided at the end edge of the exhaust pipe 16 via the mounting holes.
- the plurality of partition plates 28 are provided at predetermined intervals in the mixer body 27 so as to obstruct the passage of exhaust gas in the cylinder part 27 a .
- a case where three partition plates are provided is shown.
- Each of the three partition plates 28 is formed with a plurality of gas holes 28 a , and the three partition plates 28 are provided at predetermined intervals in the mixer body 27 .
- the positions of the plurality of gas holes 28 a formed in each of the partition plates 28 are adjusted so as not to overlap the positions of the gas holes 28 a formed in the adjacent partition plate 28 in the axis line direction of the cylinder part 27 a .
- the mixer 26 is provided in an intermediate portion between the divided exhaust pipes 16 .
- the exhaust pipe 16 is divided at a position near the upstream side of the selective reduction catalyst 21 , and the mounted members 16 a and 16 b are provided at the end edges of the divided exhaust pipes 16 .
- the mixer 26 is inserted into the divided portion, and by screw-mounting the flange members 27 d and 27 e provided at both ends of the mixer 26 to the mounted members 16 a and 16 b , respectively, the mixer 26 is provided in the exhaust pipe 16 between the liquid injection nozzle 23 and the selective reduction catalyst 21 .
- the liquid injection nozzle 23 is connected with a urea-based liquid injecting means 30 capable of injecting the urea-based liquid 32 into the exhaust gas in the exhaust pipe 16 via the injection nozzle 23 .
- the urea-based liquid injecting means 30 has a liquid supply pipe 31 one end of which is connected to the liquid injection nozzle 23 , and the other end of the liquid supply pipe 31 is connected to a liquid tank 33 in which the urea-based liquid 32 is stored.
- the liquid supply pipe 31 is provided with a liquid regulating valve 34 for regulating the quantity of the liquid 32 supplied to the liquid injection nozzle 23 , and in the liquid supply pipe 31 between the liquid regulating valve 34 and the liquid tank 33 , a pump 36 capable of supplying the liquid 32 in the liquid tank 33 to the liquid injection nozzle 23 is provided.
- the liquid regulating valve 34 is a three-way valve having first, second and third ports 34 a , 34 b and 34 c .
- the first port 34 a is connected to the discharge opening of the pump 36
- the second port 34 b is connected to the liquid injection nozzle 23
- the third port 34 c is connected to the liquid tank 33 via a return pipe 37 .
- the liquid regulating valve 34 is configured so that when the liquid regulating valve 34 is turned on, the first and second ports 34 a and 34 b communicate with each other, and when the valve 34 is turned off, the first and third ports 34 a and 34 c communicate with each other.
- a temperature sensor 43 is provided to detect the temperature of exhaust gas in the exhaust pipe 16 .
- the temperature sensor 43 is provided at the inlet of the selective reduction catalyst 21 , and is configured so as to detect the temperature of exhaust gas flowing into the selective reduction catalyst 21 as the temperature of the selective reduction catalyst 21 .
- the detection output of the temperature sensor 43 is connected to the control input of a controller 44 consisting of a microcomputer.
- a rotation sensor 46 for detecting the rotational speed of the engine 11 detection outputs of a rotation sensor 46 for detecting the rotational speed of the engine 11 , a load sensor 47 for detecting the load of the engine 11 , and the like are connected.
- the load sensor 47 detects the displacement of a load lever of a fuel injection device (not shown).
- the control output of the controller 44 is connected to the liquid regulating valve 34 and the pump 36 .
- the controller 44 has a memory 44 a . In the memory 44 a , exhaust gas temperature at the inlet of the selective reduction catalyst, on or off of the liquid regulating valve 34 according to engine rotation, engine load, and the like, the degree of opening at the on time, and the operation of the pump 36 are stored in advance.
- the controller 44 is configured so as to monitor the operating state of the engine 11 based on the detection outputs of the temperature sensor 43 , the rotation sensor 46 , and the load sensor 47 , and to control the liquid regulating valve 34 and the pump 36 according to the conditions stored in the memory 44 a from the operating state so that a proper quantity of the urea-based liquid 32 is injected from the injection nozzle 23 according to the operating state.
- the exhaust pipe 16 on the upstream side of the injection nozzle 23 is provided with a particulate filter 51 .
- the particulate filter 51 is accommodated in a cylindrical second converter 52 formed by enlarging the diameter of the exhaust pipe 16 .
- the particulate filter 51 is manufactured by carrying an active ingredient having catalytic action on a carrier.
- the carrier is formed of a porous substance consisting of ceramics such as cordierite and silicon carbide, and has a plurality of through holes partitioned by porous walls, which are formed in parallel with each other.
- the plurality of through holes have inflow-side through holes 51 a the outlet side of which is closed and the inlet side of which is open and outflow-side through holes 51 b the inlet side of which is closed and the outlet side of which is open.
- the inflow-side through holes 51 a and the outflow-side through holes 51 b are formed alternately in a state of being partitioned by the walls. Also, on the porous wall, the active ingredient is applied and carried. The active ingredient produces oxidative action. As the active ingredient, noble metal based zeolite, noble metal based alumina, or the like is used.
- the wall is configured so as to have gas permeability in the state in which the active ingredient is carried.
- the particulate filter 51 is configured so that when exhaust gas flowing into the inflow-side through hole 51 a the inlet side of which is open passes through the wall, particulates in exhaust gas are captured.
- the particulate filter 51 is configured so that the exhaust gas from which particulates have been removed by the passage through the wall flows into the outflow-side through hole 51 b the inlet side of which is closed, and is discharged to the outside of the filter 51 from the open outlet side of the outflow-side through hole 51 b.
- an oxidation catalyst 53 is provided in the exhaust pipe 16 on the exhaust gas upstream side of the particulate filter 51 .
- This oxidation catalyst 53 is accommodated in the cylindrical second converter 52 formed by enlarging the diameter of the exhaust pipe 16 on the upstream side of the injection nozzle 23 in a state of being arranged just in front of the particulate filter 51 .
- the oxidation catalyst 53 has a monolithic carrier (material: cordierite), not shown, formed with a lattice-shaped (honeycomb-shaped) passage in the direction such that exhaust gas flows, and the monolithic carrier is coated with a platinum-zeolite catalyst or a platinum-alumina catalyst. This coating gives the oxidation catalyst 53 power for oxidizing soot and hydrocarbon (HC etc.).
- an ammonia purification catalyst 54 is provided in the first converter 22 in which the selective reduction catalyst 21 is accommodated in a state of being arranged just in rear of the selective reduction catalyst 21 .
- the ammonia purification catalyst 54 has a monolithic carrier (material: cordierite), not shown, formed with a lattice-shaped (honeycomb-shaped) passage in the direction such that exhaust gas flows, and the monolithic carrier is coated with a platinum-zeolite catalyst or a platinum-alumina catalyst. This coating gives the oxidation catalyst 53 power for oxidizing ammonia.
- the diesel engine 11 is driven by burning fuel injected by the fuel injection device, not shown, in a cylinder.
- the injection device not shown, in this embodiment has an in-cylinder injector the tip end part of which faces to the cylinder and which can inject light oil, which is a fuel, into the cylinder, a common rail for accumulating light oil under pressure therein and for feeding light oil under pressure to the injector, and a feed pump for supplying light oil to the common rail.
- the in-cylinder injector is configured so that the injection amount and timing of light oil can be adjusted by an electromagnetic valve incorporated in the injector.
- This fuel injection device is configured so as to be capable of injecting light oil, which is a fuel, into the cylinder after the top dead center of piston, and is configured so as to be capable of increasing and decreasing hydrocarbon supplied from the engine 11 to the exhaust pipe 16 according to the presence or absence of injection after the top dead center.
- a specific configuration of the fuel injection device is such that both of after injection for injecting fuel when the crank angle is in the range of 30 to 50 degrees after the top dead center of piston and post injection for injecting fuel when the crank angle is in the range of 90 to 130 degrees after the top dead center of piston.
- This fuel injection device is connected with the control output of the controller 44 , and the configuration is made such that when the temperature sensor 43 detects that the selective reduction catalyst 21 has a temperature not higher than a predetermined temperature, the controller 44 accomplishes both of the after injection and the post injection.
- this predetermined temperature is an upper-limit temperature at which the urea-based liquid does not hydrolyze and moreover the activity in the selective reduction catalyst 21 decreases, and can be set arbitrarily in the range of 100 to 200° C.
- the predetermined temperature is generally set at 170° C., it may be set at 175° C., 180° C., 185° C., 190° C., 195° C. or 200° C. exceeding the generally set temperature of 170° C.
- the predetermined temperature may be set at 166° C., 160° C., 155° C., 150° C., 145° C. or 140° C. lower than the generally set temperature of 170° C.
- the configuration is made such that the controller 44 controls the fuel injection device so that both of the after injection and the post injection are accomplished when the temperature sensor 43 detects that the selective reduction catalyst has a temperature not higher than the predetermined temperature, for example, 170° C.
- the exhaust gas goes from the exhaust manifold 14 to the exhaust pipe 16 , passing through the oxidation catalyst 53 via the exhaust pipe 16 , and reaches the particulate filter 51 .
- the particulates in the exhaust gas of the diesel engine 11 are captured by the diesel particulate filter 51 .
- the exhaust gas the particulates of which have been captured and removed passes through the particulate filter 51 and reaches the selective reduction catalyst 21 after passing through the liquid injection nozzle 23 and the mixer 26 .
- the controller 44 drives the pump 36 in the liquid injecting means 30 . Simultaneously, the controller 44 turns on the liquid regulating valve 34 to cause the first and second ports 34 a and 34 b in the liquid regulating valve 34 to communicate with each other, so that the urea-based liquid 32 is injected from the liquid injection nozzle 23 .
- a reducing agent is needed to reduce NOx in exhaust gas by using the selective reduction catalyst 21 .
- the urea-based liquid 32 the concentration of which has been adjusted to a predetermined value is stored in the liquid tank 33 .
- the controller 44 estimates the concentration of NOx in exhaust gas, and determines the quantity of urea used as a reducing agent necessary for reducing this NOx, by which a necessary quantity of urea-based liquid 32 is injected from the liquid injection nozzle 23 .
- the urea-based liquid 32 injected from the liquid injection nozzle 23 flows along the flow of exhaust gas toward the selective reduction catalyst 21 , and flows into the mixer 26 provided between the liquid injection nozzle 23 and the selective reduction catalyst 21 .
- the exhaust gas flowing into the mixer 26 passes through the plurality of gas holes 28 a formed in the three partition plates 28 . Since the plurality of gas holes 28 a are formed so as not to overlap the plurality of gas holes 28 a formed in the adjacent partition plate 28 in the axis line direction, the exhaust gas passes through the mixer 26 in a zigzag form. Since the exhaust gas goes zigzag, the urea-based liquid 32 injected into the exhaust gas is mixed with the exhaust gas. Therefore, the urea-based liquid 32 having been mixed with the exhaust gas sufficiently at the stage of passing through the mixer 26 reaches the selective reduction catalyst 21 uniformly.
- the urea-based liquid 32 uniformly reaching the selective reduction catalyst 21 is heated by exhaust gas and is hydrolyzed by the following chemical reaction to yield ammonia.
- This ammonia reduces NO and NO 2 by means of the following chemical reaction to reduce the emission of NOx, and since the urea-based liquid 32 reaches the selective reduction catalyst 21 uniformly, most of the ammonia functions as a reducing agent.
- the ammonia purification catalyst 54 is provided in the exhaust pipe 16 on the exhaust gas downstream side of the selective reduction catalyst 21 , the ammonia passing through the selective reduction catalyst 21 without being used as a reducing agent is oxidized by the ammonia purification catalyst 54 and is converted to harmless N 2 and H 2 O so that the ammonia is effectively prevented from being discharged to the atmosphere.
- the controller 44 controls the fuel injection device so that fuel is injected into the cylinder after the top dead center of piston.
- the predetermined temperature is 170° C.
- the controller 44 controls the fuel injection device so that both of the after injection and the post injection are accomplished.
- the after injection injects fuel when the crank angle is in the range of 30 to 50 degrees after the top dead center of piston.
- the after injection can increase hydrocarbon in exhaust gas and burn the hydrocarbon to raise the temperature of exhaust gas flowing out of the engine 11 to the exhaust pipe 16 .
- the post injection injects fuel when the crank angle is in the range of 90 to 130 degrees after the top dead center of piston.
- the post injection increases hydrocarbon in exhaust gas and supplies the hydrocarbon from the engine 11 to the exhaust pipe 16 together with exhaust gas.
- the hydrocarbon in exhaust gas is increased, and the increased hydrocarbon undergoes oxidation reaction in the oxidation catalyst 53 provided on the upstream side of the particulate filter 51 to further raise the temperature of exhaust gas.
- the temperature of exhaust gas increases, the temperature of the particulate filter 51 is also increased, so that the particulates accumulated in the filter 51 burn. Therefore, when the particulate filter 51 is regenerated as well, the post injection is accomplished.
- the engine a turbocharged diesel engine is cited.
- the exhaust gas purification apparatus in accordance with the present invention may be used in a naturally-aspirated diesel engine.
- the configuration can be made such that the oxidation catalyst 53 is divided, and a first oxidation catalyst 53 a is provided in the exhaust pipe 16 just in rear of the turbocharger 17 and a second oxidation catalyst 53 b is further provided in the exhaust pipe 16 just in front of the diesel particulate filter 51 .
- the exhaust gas purification apparatus for an engine which is provided with the first and second oxidation catalysts 53 a and 53 b , since the temperature of exhaust gas increases immediately after the exhaust gas has passed through the turbocharger 17 , in the first oxidation catalyst 53 a provided in the exhaust pipe 16 just in rear of the turbocharger 17 , some of the fuel injected after the top dead center of piston can be burned surely to raise the temperature of exhaust gas. By burning the remaining fuel in the second oxidation catalyst 53 b , the temperature of exhaust gas can be raised stepwise to rapidly increase the temperature of the selective reduction catalyst 21 .
- the present invention can be applied to an exhaust gas purification apparatus for an engine, which removes nitrogen oxides contained in exhaust gas of a diesel engine to purify the exhaust gas.
Abstract
There is provided an exhaust gas purification apparatus for an engine capable of effectively removing NOx in exhaust gas even when the temperature of exhaust gas is relatively low. The exhaust gas purification apparatus includes a selective reduction catalyst provided in an exhaust pipe, a liquid injection nozzle provided on the upstream side of the selective reduction catalyst, a liquid injecting means capable of injecting a urea-based liquid via the liquid injection nozzle, a controller, and a mixer. The apparatus further includes an ammonia purification catalyst provided on the downstream side of the selective reduction catalyst, a diesel particulate filter provided on the upstream side of the nozzle, an oxidation catalyst provided on the upstream side of the diesel particulate filter, and a temperature sensor for detecting the temperature of the selective reduction catalyst. A fuel injection device is configured so as to be capable of injecting fuel into a cylinder after the top dead center of piston, and when the temperature sensor detects that the selective reduction catalyst has a temperature not higher than a predetermined temperature, the controller controls the fuel injection device so that fuel is injected into the cylinder after the top dead center of piston.
Description
- This is a U.S. national phase application under 35 U.S.C. § 371 of International Patent Application No. PCT/JP2007/067903 filed Sep. 14, 2007 and claims the benefit of Japanese Application No. 2006-255634 filed Sep. 21, 2006. The International Application was published on Mar. 27, 2008 as International Publication No. WO/2008/035623 under PCT Article 21(2) the contents of these applications are incorporated herein in their entirety.
- The present invention relates to an exhaust gas purification apparatus for an engine, which removes nitrogen oxides contained in exhaust gas of a diesel engine to purify the exhaust gas.
- Conventionally, as an exhaust gas purification apparatus for reducing nitrogen oxides (hereinafter abbreviated as NOx) contained in exhaust gas of a diesel engine, there has been known an exhaust gas purification apparatus for a diesel engine, in which a selective reduction catalyst is provided midway in an exhaust passage of the diesel engine, and a liquid injection nozzle capable of injecting a urea-based liquid toward the selective reduction catalyst is provided in an exhaust pipe on the exhaust gas upstream side of the selective reduction catalyst. In this exhaust gas purification apparatus for a diesel engine, the urea-based liquid injected from the liquid injection nozzle is heated by the heat of exhaust gas and is hydrolyzed, by which ammonia is yielded. This ammonia functions as a reducing agent for reducing NOx in exhaust gas by using the selective reduction catalyst so that the quantity of NOx discharged to the atmosphere can be decreased. To uniformize the urea-based liquid reaching the selective reduction catalyst and to reduce NOx emission, a proposal has been made that a mixer configured so that the liquid injected from the liquid injection nozzle can be mixed with exhaust gas is provided in an exhaust pipe between the liquid injection nozzle and the selective reduction catalyst (for example, refer to Japanese Unexamined Patent Application Publication No. 2003-232218 (“JP '218”) (Clams for the Patent, FIG. 1)
- However, ammonia yielded by the hydrolysis of urea-based liquid functions as a reducing agent only when the temperature of exhaust gas is relatively high. When the temperature of exhaust gas is relatively low, ammonia does not function as a reducing agent. For this reason, in the exhaust gas purification apparatus using the selective reduction catalyst in the exhaust pipe, there remains an unsolved problem in that NOx in exhaust gas cannot be removed effectively when the temperature of exhaust gas is relatively low.
- An object of the present invention is to provide an exhaust gas purification apparatus for an engine capable of effectively removing NOx in exhaust gas even when the temperature of exhaust gas is relatively low.
- The invention is an improvement in an exhaust gas purification apparatus including, as shown in
FIG. 1 , aselective reduction catalyst 21 provided in anexhaust pipe 16 of adiesel engine 11 driven by burning a fuel, which is injected from a fuel injection device, in a cylinder; aliquid injection nozzle 23 provided in theexhaust pipe 16 on the exhaust gas upstream side of theselective reduction catalyst 21; a liquid injecting means 30 capable of injecting a urea-basedliquid 32 toward theselective reduction catalyst 21 via theliquid injection nozzle 23; acontroller 44 for controlling the liquid injecting means 30; and amixer 26 that is provided in theexhaust pipe 16 between theliquid injection nozzle 23 and theselective reduction catalyst 21 and is configured so that theliquid 32 injected from theliquid injection nozzle 23 is mixed with exhaust gas. - The characteristic configuration of the above-described exhaust gas purification apparatus is that the apparatus further includes an
ammonia purification catalyst 54 provided in theexhaust pipe 16 on the exhaust gas downstream side of theselective reduction catalyst 21; adiesel particulate filter 51 provided in theexhaust pipe 16 on the exhaust gas upstream side of theliquid injection nozzle 23; anoxidation catalyst 53 provided in theexhaust pipe 16 on the exhaust gas upstream side of thediesel particulate filter 51; and atemperature sensor 43 for detecting the temperature of theselective reduction catalyst 21 and sending the detected temperature to thecontroller 44, the fuel injection device is configured so as to be capable of injecting the fuel into the cylinder after the top dead center of piston, and when thetemperature sensor 43 detects that theselective reduction catalyst 21 has a temperature not higher than 170° C., thecontroller 44 controls the fuel injection device so that the fuel is injected into the cylinder after the top dead center of piston. - In the exhaust gas purification apparatus for an engine when the urea-based
liquid 32 is injected from theliquid injection nozzle 23, theliquid 32 flows into themixer 26, being sufficiently mixed with exhaust gas, and reaches theselective reduction catalyst 21 uniformly. In theselective reduction catalyst 21, the urea-basedliquid 32 is heated by exhaust gas and is hydrolyzed, and ammonia yielded by the hydrolysis reduces NO and NO2, by which the emission of NOx is reduced. Theammonia purification catalyst 54 oxidizes ammonia passing through theselective reduction catalyst 21 without being used as a reducing agent, by which the ammonia is converted to harmless N2 and H2O so that the ammonia is effectively prevented from being discharged to the atmosphere. Also, theparticulate filter 51 captures particulates in the exhaust gas of thediesel engine 11, so that the particulates can be effectively prevented from being discharged to the outside. - The invention is characterized further in that the fuel injection device is configured so as to be capable of injecting the fuel into a cylinder after the top dead center of piston; the
temperature sensor 43 is provided at the inlet of theselective reduction catalyst 21 and is configured so as to be capable of measuring the temperature of exhaust gas flowing into theselective reduction catalyst 21; and when thetemperature sensor 43 detects a temperature not higher than a predetermined temperature, thecontroller 44 controls the fuel injection device so that the fuel is injected into the cylinder after the top dead center of piston. - In the exhaust gas purification apparatus for an engine, when the fuel is injected into the cylinder after the top dead center of piston by the fuel injection device, the fuel burns in the
exhaust pipe 16, or undergoes oxidation reaction in theoxidation catalyst 53 provided on the upstream side of theparticulate filter 51 to remarkably raise the temperature of exhaust gas, by which the temperature of theselective reduction catalyst 21 on the downstream side of theparticulate filter 51 is increased rapidly. For this purpose, when thetemperature sensor 43 detects that theselective reduction catalyst 21 has a temperature not higher than the predetermined temperature at which the urea-based liquid does not hydrolyze and moreover the activity in theselective reduction catalyst 21 decreases, thecontroller 44 controls the fuel injection device so that the fuel is injected into the cylinder after the top dead center of piston. Thereby, the temperature of theselective reduction catalyst 21 is increased rapidly, and therefore NOx in exhaust gas can be removed effectively. - Also, if the quantity of particulates captured by the
particulate filter 51 increases, the resistance of exhaust gas passing through theparticulate filter 51 increases. In this case, the fuel is injected into the cylinder after the top dead center of piston by the fuel injection device, and the fuel is burned in theparticulate filter 51 together with the particulates, by which theparticulate filter 51 can be regenerated. - The invention is characterized further in that a
turbocharger 17 is provided on theengine 11, and theoxidation catalyst 53 consists of a first oxidation catalyst 53 a provided in theexhaust pipe 16 just in rear of theturbocharger 17 and asecond oxidation catalyst 53 b provided in theexhaust pipe 16 just in front of thediesel particulate filter 51. - In the exhaust gas purification apparatus for an engine, temperature of exhaust gas immediately after passing through the
turbocharger 17 rises. Therefore, in the first oxidation catalyst 53 a provided in theexhaust pipe 16 just in rear of theturbocharger 17, some of the fuel injected after the top dead center of piston can be burned surely to raise the temperature of exhaust gas. By burning the remaining fuel in thesecond oxidation catalyst 53 b, the temperature of exhaust gas can be raised stepwise to rapidly increase the temperature of theselective reduction catalyst 21. - The invention is characterized further in that the fuel injection device is configured so as to be capable of accomplishing both of after injection for injecting the fuel when the crank angle is in the range of 30 to 50 degrees after the top dead center of piston and post injection for injecting the fuel when the crank angle is in the range of 90 to 130 degrees after the top dead center of piston; and when the
temperature sensor 43 detects that theselective reduction catalyst 21 has a temperature not higher than the predetermined temperature, thecontroller 44 controls the fuel injection device so that both of the after injection and the post injection are accomplished. - In the exhaust gas purification apparatus for an engine, the after injection can increase hydrocarbon in exhaust gas and burn the hydrocarbon to raise the temperature of exhaust gas flowing out of the
engine 11 to theexhaust pipe 16. Also, the post injection can cause the hydrocarbon increased in exhaust gas to undergo oxidation reaction in theoxidation catalyst 53 provided on the upstream side of theparticulate filter 51 to further raise the temperature of exhaust gas, by which the temperature of theselective reduction catalyst 21 can be increased rapidly. - In the exhaust gas purification apparatus for an engine, since the liquid injection nozzle, the mixer, and the selective reduction catalyst are provided, when the urea-based liquid is injected from the injection nozzle, the urea-based liquid flows into the mixer, being mixed with exhaust gas, and reaches the selective reduction catalyst. In the selective reduction catalyst, the urea-based liquid is hydrolyzed, and ammonia yielded by the hydrolysis reduces NO and NO2, by which the emission of NOx is reduced. The ammonia purification catalyst provided in the exhaust pipe on the downstream side of the selective reduction catalyst oxidizes ammonia passing through the selective reduction catalyst without being used as a reducing agent, by which the ammonia is converted to harmless N2 and H2O so that the ammonia is effectively prevented from being discharged to the atmosphere.
- On the other hand, when the fuel is injected into the cylinder after the top dead center of piston by the fuel injection device, the fuel burns in the exhaust pipe, or undergoes oxidation reaction in the oxidation catalyst provided on the upstream side of the particulate filter to remarkably raise the temperature of exhaust gas, by which the temperature of the selective reduction catalyst on the downstream side of the particulate filter is increased rapidly. For this purpose, when the temperature sensor detects that the selective reduction catalyst has a temperature at which the urea-based liquid does not hydrolyze, the controller controls the fuel injection device so that the fuel is injected into the cylinder after the top dead center of piston. Thereby, the temperature of the selective reduction catalyst is increased rapidly, and therefore NOx in exhaust gas can be removed effectively.
- Also, since the diesel particulate filter is provided in the exhaust pipe on the exhaust gas upstream side of the liquid injection nozzle, the particulate filter captures particulates in exhaust gas of the diesel engine to effectively prevent the particulates from being discharged to the outside. If the quantity of captured particulates increases, the resistance of exhaust gas passing through the particulate filter increases. However, by injecting the fuel into the cylinder after the top dead center of piston and by burning the fuel, the particulate filter can be regenerated.
-
FIG. 1 is a general view showing a configuration of an exhaust gas purification apparatus in accordance with an embodiment of the present invention; and -
FIG. 2 is a general view showing a configuration of an exhaust gas purification apparatus corresponding to the apparatus shown inFIG. 1 , which is provided with first and second oxidation catalysts. - A best mode for carrying out the invention will now be described with reference to the accompanying drawings.
- As shown in
FIG. 1 , the intake port of adiesel engine 11 is connected with anintake pipe 13 via anintake manifold 12, and the exhaust port thereof is connected with anexhaust pipe 16 via anexhaust manifold 14. Theintake pipe 13 is provided with acompressor 17 a of aturbocharger 17 and an inter-cooler 18 for cooling intake air compressed by theturbocharger 17, and theexhaust pipe 16 is provided with aturbine 17 b of theturbocharger 17. Although not shown, the rotary vane of thecompressor 17 a and the rotary vane of theturbine 17 b are connected to each other by a shaft. The configuration is made such that thecompressor 17 a is rotated via theturbine 17 b and the shaft by the energy of exhaust gas discharged from theengine 11, by which intake air in theintake pipe 13 is compressed by the rotation of thecompressor 17 a. - In the middle of the
exhaust pipe 16, aselective reduction catalyst 21 is provided. Thecatalyst 21 is accommodated in a cylindricalfirst converter 22 formed by enlarging the diameter of theexhaust pipe 16. In this embodiment, there is shown a case where a copper zeolite catalyst, which reduces NOx in exhaust gas flowing into theexhaust pipe 16 at a relatively low temperature of 200 to 300° C., is used as thecatalyst 21. However, a catalyst consisting of titanium oxide, vanadium oxide, or tungsten oxide may also be used. In theexhaust pipe 16 on the exhaust gas upstream side of thecatalyst 21, that is, at the inlet of thecatalyst 21, aliquid injection nozzle 23 capable of injecting a urea-basedliquid 32 is provided so as to be directed toward thecatalyst 21, and in theexhaust pipe 16 between theliquid injection nozzle 23 and theselective reduction catalyst 21, amixer 26 configured so as to be capable of mixing the urea-basedliquid 32 injected from theliquid injection nozzle 23 with exhaust gas is provided. - The
mixer 26 of this embodiment includes amixer body 27 having acylinder part 27 a through which exhaust gas passes in the axis line direction, and a plurality ofpartition plates 28 provided in themixer body 27. Themixer body 27 is manufactured bywelding lid bodies cylinder part 27 a formed by fabricating a stainless steel sheet into a cylindrical shape. That is to say, one end part facing to thecylinder part 27 a of each of thelid bodies cylinder part 27 a and is welded to thecylinder part 27 a. On the other hand, the other end part of each of thelid bodies exhaust pipe 16, and to the outer periphery of the other end part, ring-shaped flange members lid body exhaust pipe 16 are welded. Theflange members members exhaust pipe 16 via the mounting holes. - On the other hand, the plurality of
partition plates 28 are provided at predetermined intervals in themixer body 27 so as to obstruct the passage of exhaust gas in thecylinder part 27 a. In this embodiment, a case where three partition plates are provided is shown. Each of the threepartition plates 28 is formed with a plurality of gas holes 28 a, and the threepartition plates 28 are provided at predetermined intervals in themixer body 27. The positions of the plurality of gas holes 28 a formed in each of thepartition plates 28 are adjusted so as not to overlap the positions of the gas holes 28 a formed in theadjacent partition plate 28 in the axis line direction of thecylinder part 27 a. Themixer 26 is provided in an intermediate portion between the dividedexhaust pipes 16. That is to say, theexhaust pipe 16 is divided at a position near the upstream side of theselective reduction catalyst 21, and the mountedmembers exhaust pipes 16. Themixer 26 is inserted into the divided portion, and by screw-mounting theflange members mixer 26 to the mountedmembers mixer 26 is provided in theexhaust pipe 16 between theliquid injection nozzle 23 and theselective reduction catalyst 21. - The
liquid injection nozzle 23 is connected with a urea-based liquid injecting means 30 capable of injecting the urea-basedliquid 32 into the exhaust gas in theexhaust pipe 16 via theinjection nozzle 23. The urea-based liquid injecting means 30 has aliquid supply pipe 31 one end of which is connected to theliquid injection nozzle 23, and the other end of theliquid supply pipe 31 is connected to aliquid tank 33 in which the urea-basedliquid 32 is stored. Also, theliquid supply pipe 31 is provided with aliquid regulating valve 34 for regulating the quantity of the liquid 32 supplied to theliquid injection nozzle 23, and in theliquid supply pipe 31 between the liquid regulatingvalve 34 and theliquid tank 33, apump 36 capable of supplying the liquid 32 in theliquid tank 33 to theliquid injection nozzle 23 is provided. Theliquid regulating valve 34 is a three-way valve having first, second andthird ports first port 34 a is connected to the discharge opening of thepump 36, thesecond port 34 b is connected to theliquid injection nozzle 23, and the third port 34 c is connected to theliquid tank 33 via areturn pipe 37. Theliquid regulating valve 34 is configured so that when theliquid regulating valve 34 is turned on, the first andsecond ports valve 34 is turned off, the first andthird ports 34 a and 34 c communicate with each other. - On the other hand, in the
exhaust pipe 16, atemperature sensor 43 is provided to detect the temperature of exhaust gas in theexhaust pipe 16. Thetemperature sensor 43 is provided at the inlet of theselective reduction catalyst 21, and is configured so as to detect the temperature of exhaust gas flowing into theselective reduction catalyst 21 as the temperature of theselective reduction catalyst 21. The detection output of thetemperature sensor 43 is connected to the control input of acontroller 44 consisting of a microcomputer. - Also, to the control input of the
controller 44, detection outputs of arotation sensor 46 for detecting the rotational speed of theengine 11, aload sensor 47 for detecting the load of theengine 11, and the like are connected. In this embodiment, theload sensor 47 detects the displacement of a load lever of a fuel injection device (not shown). The control output of thecontroller 44 is connected to theliquid regulating valve 34 and thepump 36. Thecontroller 44 has amemory 44 a. In thememory 44 a, exhaust gas temperature at the inlet of the selective reduction catalyst, on or off of theliquid regulating valve 34 according to engine rotation, engine load, and the like, the degree of opening at the on time, and the operation of thepump 36 are stored in advance. Thecontroller 44 is configured so as to monitor the operating state of theengine 11 based on the detection outputs of thetemperature sensor 43, therotation sensor 46, and theload sensor 47, and to control theliquid regulating valve 34 and thepump 36 according to the conditions stored in thememory 44 a from the operating state so that a proper quantity of the urea-basedliquid 32 is injected from theinjection nozzle 23 according to the operating state. - The
exhaust pipe 16 on the upstream side of theinjection nozzle 23 is provided with aparticulate filter 51. Theparticulate filter 51 is accommodated in a cylindricalsecond converter 52 formed by enlarging the diameter of theexhaust pipe 16. Theparticulate filter 51 is manufactured by carrying an active ingredient having catalytic action on a carrier. The carrier is formed of a porous substance consisting of ceramics such as cordierite and silicon carbide, and has a plurality of through holes partitioned by porous walls, which are formed in parallel with each other. The plurality of through holes have inflow-side throughholes 51 a the outlet side of which is closed and the inlet side of which is open and outflow-side throughholes 51 b the inlet side of which is closed and the outlet side of which is open. The inflow-side throughholes 51 a and the outflow-side throughholes 51 b are formed alternately in a state of being partitioned by the walls. Also, on the porous wall, the active ingredient is applied and carried. The active ingredient produces oxidative action. As the active ingredient, noble metal based zeolite, noble metal based alumina, or the like is used. The wall is configured so as to have gas permeability in the state in which the active ingredient is carried. Theparticulate filter 51 is configured so that when exhaust gas flowing into the inflow-side throughhole 51 a the inlet side of which is open passes through the wall, particulates in exhaust gas are captured. Also, theparticulate filter 51 is configured so that the exhaust gas from which particulates have been removed by the passage through the wall flows into the outflow-side throughhole 51 b the inlet side of which is closed, and is discharged to the outside of thefilter 51 from the open outlet side of the outflow-side throughhole 51 b. - Also, in the
exhaust pipe 16 on the exhaust gas upstream side of theparticulate filter 51, anoxidation catalyst 53 is provided. Thisoxidation catalyst 53 is accommodated in the cylindricalsecond converter 52 formed by enlarging the diameter of theexhaust pipe 16 on the upstream side of theinjection nozzle 23 in a state of being arranged just in front of theparticulate filter 51. Although not shown, theoxidation catalyst 53 has a monolithic carrier (material: cordierite), not shown, formed with a lattice-shaped (honeycomb-shaped) passage in the direction such that exhaust gas flows, and the monolithic carrier is coated with a platinum-zeolite catalyst or a platinum-alumina catalyst. This coating gives theoxidation catalyst 53 power for oxidizing soot and hydrocarbon (HC etc.). - Further, in the
exhaust pipe 16 on the exhaust gas downstream side of theselective reduction catalyst 21, anammonia purification catalyst 54 is provided. Theammonia purification catalyst 54 is accommodated in thefirst converter 22 in which theselective reduction catalyst 21 is accommodated in a state of being arranged just in rear of theselective reduction catalyst 21. Theammonia purification catalyst 54 has a monolithic carrier (material: cordierite), not shown, formed with a lattice-shaped (honeycomb-shaped) passage in the direction such that exhaust gas flows, and the monolithic carrier is coated with a platinum-zeolite catalyst or a platinum-alumina catalyst. This coating gives theoxidation catalyst 53 power for oxidizing ammonia. - On the other hand, the
diesel engine 11 is driven by burning fuel injected by the fuel injection device, not shown, in a cylinder. The injection device, not shown, in this embodiment has an in-cylinder injector the tip end part of which faces to the cylinder and which can inject light oil, which is a fuel, into the cylinder, a common rail for accumulating light oil under pressure therein and for feeding light oil under pressure to the injector, and a feed pump for supplying light oil to the common rail. The in-cylinder injector is configured so that the injection amount and timing of light oil can be adjusted by an electromagnetic valve incorporated in the injector. This fuel injection device is configured so as to be capable of injecting light oil, which is a fuel, into the cylinder after the top dead center of piston, and is configured so as to be capable of increasing and decreasing hydrocarbon supplied from theengine 11 to theexhaust pipe 16 according to the presence or absence of injection after the top dead center. A specific configuration of the fuel injection device is such that both of after injection for injecting fuel when the crank angle is in the range of 30 to 50 degrees after the top dead center of piston and post injection for injecting fuel when the crank angle is in the range of 90 to 130 degrees after the top dead center of piston. This fuel injection device is connected with the control output of thecontroller 44, and the configuration is made such that when thetemperature sensor 43 detects that theselective reduction catalyst 21 has a temperature not higher than a predetermined temperature, thecontroller 44 accomplishes both of the after injection and the post injection. Specifically, this predetermined temperature is an upper-limit temperature at which the urea-based liquid does not hydrolyze and moreover the activity in theselective reduction catalyst 21 decreases, and can be set arbitrarily in the range of 100 to 200° C. Although the predetermined temperature is generally set at 170° C., it may be set at 175° C., 180° C., 185° C., 190° C., 195° C. or 200° C. exceeding the generally set temperature of 170° C. Also, the predetermined temperature may be set at 166° C., 160° C., 155° C., 150° C., 145° C. or 140° C. lower than the generally set temperature of 170° C. The configuration is made such that thecontroller 44 controls the fuel injection device so that both of the after injection and the post injection are accomplished when thetemperature sensor 43 detects that the selective reduction catalyst has a temperature not higher than the predetermined temperature, for example, 170° C. - The operation of the exhaust gas purification apparatus for an engine configured as described above is explained.
- When the
engine 11 is started, the exhaust gas goes from theexhaust manifold 14 to theexhaust pipe 16, passing through theoxidation catalyst 53 via theexhaust pipe 16, and reaches theparticulate filter 51. The particulates in the exhaust gas of thediesel engine 11 are captured by thediesel particulate filter 51. The exhaust gas the particulates of which have been captured and removed passes through theparticulate filter 51 and reaches theselective reduction catalyst 21 after passing through theliquid injection nozzle 23 and themixer 26. - When the exhaust gas has a temperature at which urea is hydrolyzed, specifically in this embodiment, when the
temperature sensor 43 detects an exhaust gas temperature exceeding the predetermined temperature, which is a temperature at which urea is hydrolyzed, for example, 170° C., thecontroller 44 drives thepump 36 in the liquid injecting means 30. Simultaneously, thecontroller 44 turns on theliquid regulating valve 34 to cause the first andsecond ports liquid regulating valve 34 to communicate with each other, so that the urea-basedliquid 32 is injected from theliquid injection nozzle 23. The reason for this is that a reducing agent is needed to reduce NOx in exhaust gas by using theselective reduction catalyst 21. The urea-basedliquid 32 the concentration of which has been adjusted to a predetermined value is stored in theliquid tank 33. From the operating state of thediesel engine 11, which is determined based on the detection outputs of therotation sensor 46 and theload sensor 47, thecontroller 44 estimates the concentration of NOx in exhaust gas, and determines the quantity of urea used as a reducing agent necessary for reducing this NOx, by which a necessary quantity of urea-basedliquid 32 is injected from theliquid injection nozzle 23. - The urea-based
liquid 32 injected from theliquid injection nozzle 23 flows along the flow of exhaust gas toward theselective reduction catalyst 21, and flows into themixer 26 provided between theliquid injection nozzle 23 and theselective reduction catalyst 21. The exhaust gas flowing into themixer 26 passes through the plurality of gas holes 28 a formed in the threepartition plates 28. Since the plurality of gas holes 28 a are formed so as not to overlap the plurality of gas holes 28 a formed in theadjacent partition plate 28 in the axis line direction, the exhaust gas passes through themixer 26 in a zigzag form. Since the exhaust gas goes zigzag, the urea-basedliquid 32 injected into the exhaust gas is mixed with the exhaust gas. Therefore, the urea-basedliquid 32 having been mixed with the exhaust gas sufficiently at the stage of passing through themixer 26 reaches theselective reduction catalyst 21 uniformly. - The urea-based
liquid 32 uniformly reaching theselective reduction catalyst 21 is heated by exhaust gas and is hydrolyzed by the following chemical reaction to yield ammonia. -
(NH2)2.CO+H2O→CO2+2NH3 - This ammonia reduces NO and NO2 by means of the following chemical reaction to reduce the emission of NOx, and since the urea-based
liquid 32 reaches theselective reduction catalyst 21 uniformly, most of the ammonia functions as a reducing agent. -
4NO+4NH3+O2→4N2+6H2O -
6NO2+8NH3→7N2+12H2O - On the other hand, since the
ammonia purification catalyst 54 is provided in theexhaust pipe 16 on the exhaust gas downstream side of theselective reduction catalyst 21, the ammonia passing through theselective reduction catalyst 21 without being used as a reducing agent is oxidized by theammonia purification catalyst 54 and is converted to harmless N2 and H2O so that the ammonia is effectively prevented from being discharged to the atmosphere. - On the other hand, when the
temperature sensor 43 detects that theselective reduction catalyst 21 has a temperature not higher than the predetermined temperature at which the urea-based liquid does not hydrolyze and moreover the activity in theselective reduction catalyst 21 decreases, for example, 170° C., thecontroller 44 controls the fuel injection device so that fuel is injected into the cylinder after the top dead center of piston. The case where the predetermined temperature is 170° C. is explained concretely. When thetemperature sensor 43 detects that theselective reduction catalyst 21 has a temperature not higher than 170° C., thecontroller 44 controls the fuel injection device so that both of the after injection and the post injection are accomplished. The after injection injects fuel when the crank angle is in the range of 30 to 50 degrees after the top dead center of piston. The after injection can increase hydrocarbon in exhaust gas and burn the hydrocarbon to raise the temperature of exhaust gas flowing out of theengine 11 to theexhaust pipe 16. On the other hand, the post injection injects fuel when the crank angle is in the range of 90 to 130 degrees after the top dead center of piston. The post injection increases hydrocarbon in exhaust gas and supplies the hydrocarbon from theengine 11 to theexhaust pipe 16 together with exhaust gas. Then, the hydrocarbon in exhaust gas is increased, and the increased hydrocarbon undergoes oxidation reaction in theoxidation catalyst 53 provided on the upstream side of theparticulate filter 51 to further raise the temperature of exhaust gas. When the temperature of exhaust gas increases, the temperature of theparticulate filter 51 is also increased, so that the particulates accumulated in thefilter 51 burn. Therefore, when theparticulate filter 51 is regenerated as well, the post injection is accomplished. - When oxidation reaction occurs in the
oxidation catalyst 53 to increase the temperature of theparticulate filter 51, the temperature of exhaust gas passing through thefilter 51 increases further, and therefore the temperature of theselective reduction catalyst 21 on the downstream side of thefilter 51 increases rapidly to a temperature at which the urea-based liquid is hydrolyzed, so that the ammonia functions as a reducing agent for NOx. Therefore, in the exhaust gas purification apparatus in accordance with the present invention, even when the temperature of exhaust gas is relatively low, NOx in exhaust gas can be removed effectively. - In the above-described embodiment, as the engine, a turbocharged diesel engine is cited. However, the exhaust gas purification apparatus in accordance with the present invention may be used in a naturally-aspirated diesel engine.
- Also, in the above-described embodiment, the case where a
single oxidation catalyst 53 is provided in theexhaust pipe 16 on the upstream side of thediesel particulate filter 51 has been explained. However, as shown inFIG. 2 , in the case where theturbocharger 17 is provided on theengine 11, the configuration can be made such that theoxidation catalyst 53 is divided, and a first oxidation catalyst 53 a is provided in theexhaust pipe 16 just in rear of theturbocharger 17 and asecond oxidation catalyst 53 b is further provided in theexhaust pipe 16 just in front of thediesel particulate filter 51. In the exhaust gas purification apparatus for an engine, which is provided with the first andsecond oxidation catalysts 53 a and 53 b, since the temperature of exhaust gas increases immediately after the exhaust gas has passed through theturbocharger 17, in the first oxidation catalyst 53 a provided in theexhaust pipe 16 just in rear of theturbocharger 17, some of the fuel injected after the top dead center of piston can be burned surely to raise the temperature of exhaust gas. By burning the remaining fuel in thesecond oxidation catalyst 53 b, the temperature of exhaust gas can be raised stepwise to rapidly increase the temperature of theselective reduction catalyst 21. - The present invention can be applied to an exhaust gas purification apparatus for an engine, which removes nitrogen oxides contained in exhaust gas of a diesel engine to purify the exhaust gas.
Claims (4)
1. An exhaust gas purification apparatus comprising:
a selective reduction catalyst provided in an exhaust pipe of a diesel engine driven by burning a fuel, which is injected from a fuel injection device, in a cylinder;
a liquid injection nozzle provided in the exhaust pipe on the exhaust gas upstream side of the selective reduction catalysts;
a liquid injecting means capable of injecting a urea-based liquid toward the selective reduction catalyst via the liquid injection nozzle;
a controller for controlling the liquid injecting means; and
a mixer which is provided in the exhaust pipe between the liquid injection nozzle and the selective reduction catalyst and is configured so that the liquid injected from the liquid injection nozzle is mixed with exhaust gas, characterized in that
the exhaust gas purification apparatus further comprises:
an ammonia purification catalyst provided in the exhaust pipe on the exhaust gas downstream side of the selective reduction catalyst;
a diesel particulate filter provided in the exhaust pipe on the exhaust gas upstream side of the liquid injection nozzle;
an oxidation catalyst provided in the exhaust pipe on the exhaust gas upstream side of the diesel particulate filter; and
a temperature sensor for detecting the temperature of the selective reduction catalyst and sending the detected temperature to the controllers.
2. The exhaust gas purification apparatus according to claim 1 , wherein
the fuel injection device is configured so as to be capable of injecting the fuel into the cylinder after the top dead center of piston;
the temperature sensor is provided at the inlet of the selective reduction catalyst and is configured so as to be capable of measuring the temperature of exhaust gas flowing into the selective reduction catalyst; and
when the temperature sensor detects a temperature not higher than a predetermined temperature, the controller controls the fuel injection device so that the fuel is injected into the cylinder after the top dead center of piston.
3. The exhaust gas purification apparatus according to claim 2 , wherein a turbocharger is provided on the engine, and the oxidation catalyst consists of a first oxidation catalyst provided in the exhaust pipe just in rear of the turbocharger and a second oxidation catalyst provided in the exhaust pipe just in front of the diesel particulate filter.
4. The exhaust gas purification apparatus according to claim 2 , wherein
the fuel injection device is configured so as to be capable of accomplishing both of after injection for injecting the fuel when the crank angle is in the range of 30 to 50 degrees after the top dead center of piston and post injection for injecting the fuel when the crank angle is in the range of 90 to 130 degrees after the top dead center of piston; and
when the temperature sensor detects that the selective reduction catalyst has a temperature not higher than the predetermined temperature, the controller controls the fuel injection device so that both of the after injection and the post injection are accomplished.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2006255634A JP2008075543A (en) | 2006-09-21 | 2006-09-21 | Exhaust emission control device for engine |
JP2006-255634 | 2006-09-21 | ||
PCT/JP2007/067903 WO2008035623A1 (en) | 2006-09-21 | 2007-09-14 | Engine exhaust gas purification apparatus |
Publications (1)
Publication Number | Publication Date |
---|---|
US20100005787A1 true US20100005787A1 (en) | 2010-01-14 |
Family
ID=39200449
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US12/441,412 Abandoned US20100005787A1 (en) | 2006-09-21 | 2007-09-14 | Exhaust gas purification apparatus for engine |
Country Status (4)
Country | Link |
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US (1) | US20100005787A1 (en) |
EP (1) | EP2065577A1 (en) |
JP (1) | JP2008075543A (en) |
WO (1) | WO2008035623A1 (en) |
Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20110047986A1 (en) * | 2009-08-17 | 2011-03-03 | Drasner Iii Henry Joseph | Retrofit Aftertreatment System for Treating Diesel Exhaust |
US20110219754A1 (en) * | 2010-03-05 | 2011-09-15 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purification apparatus of an internal combustion engine |
WO2011152830A1 (en) * | 2010-06-04 | 2011-12-08 | International Engine Intellectual Property Company, Llc | System and method for injecting ammonia into an exhaust gas stream |
US20120117946A1 (en) * | 2010-11-11 | 2012-05-17 | Gm Global Technology Operations, Inc. | Control method and apparatus for regenerating a particulate filter |
CN103827022A (en) * | 2011-09-21 | 2014-05-28 | 日野自动车株式会社 | Exhaust gas purifier |
US20140250168A1 (en) * | 2011-07-14 | 2014-09-04 | Ayodele Damola | Optimization engine in a mobile cloud accelerator and related methods |
US20150013310A1 (en) * | 2013-07-15 | 2015-01-15 | Ford Global Technology, Llc | Emission control system including an oxidation catalyst and selective catalytic reduction catalyst |
CN104454086A (en) * | 2014-12-08 | 2015-03-25 | 山东大学 | DPF (diesel particulate filter) initiative regeneration system with combustor |
WO2015128247A1 (en) * | 2014-02-28 | 2015-09-03 | Haldor Topsøe A/S | Method for the cleaning of exhaust gas from a compression ignition engine |
US20160032802A1 (en) * | 2013-03-18 | 2016-02-04 | Yanmar Co., Ltd. | Exhaust purification system and ship comprising same |
EP2868882A4 (en) * | 2012-05-31 | 2016-05-18 | Ud Trucks Corp | Method for improving durability of exhaust-gas pipe, and exhaust-gas purification device |
US9822688B2 (en) | 2015-06-24 | 2017-11-21 | Ford Global Technologies, Llc | Exhaust flow device |
US10066530B2 (en) | 2015-11-17 | 2018-09-04 | Ford Global Technologies, Llc | Exhaust gas mixer |
US10086332B2 (en) | 2015-05-07 | 2018-10-02 | Ford Global Technologies, Llc | Exhaust flow device |
US10646935B2 (en) | 2006-11-28 | 2020-05-12 | The Hillman Group, Inc. | Self service key duplicating machine with automatic key model identification system |
WO2021071299A1 (en) * | 2019-10-11 | 2021-04-15 | 서울대학교산학협력단 | Exhaust gas post-processing system control device |
US20220298428A1 (en) * | 2019-11-13 | 2022-09-22 | Haldor Topsøe A/S | Halides removal washing system for a hydrocarbon stream |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2960593B1 (en) * | 2010-05-27 | 2012-12-28 | Peugeot Citroen Automobiles Sa | EXHAUST GAS POST-TREATMENT DEVICE OF A COMBUSTION ENGINE |
EP2529091B1 (en) * | 2010-01-25 | 2016-04-06 | Peugeot Citroën Automobiles SA | Exhaust gas aftertreatment device of an internal combustion engine |
EP2977096B1 (en) * | 2013-03-22 | 2020-08-19 | NGK Insulators, Ltd. | Reducing agent injection device, exhaust gas treatment device and exhaust gas treatment method |
EP2826971A1 (en) | 2013-07-17 | 2015-01-21 | DEUTZ Aktiengesellschaft | Method for reducing nitrogen oxides in diesel engine exhaust gases and exhaust gas treatment system for carrying out the method |
Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6347831B1 (en) * | 1999-10-18 | 2002-02-19 | Lifetime Products, Inc. | Foldable picnic table with telescoping pedestals and bench supports |
US20030110761A1 (en) * | 2001-12-13 | 2003-06-19 | Isuzu Motors Limited | Exhaust emission purification system for diesel engine |
EP1363009A1 (en) * | 2001-02-20 | 2003-11-19 | Isuzu Motors Limited | Fuel injection control method for diesel engine and regenerative control method for exhaust gas after treatment device |
US20040200271A1 (en) * | 2003-04-11 | 2004-10-14 | Van Nieuwstadt Michiel J. | Pressure sensor diagnosis via a computer |
US20050086933A1 (en) * | 2003-10-27 | 2005-04-28 | Nieuwstadt Michiel V. | Method and system for controlling simultaneous diesel particulate filter regeneration and lean NOx trap desulfation |
US20060059900A1 (en) * | 2004-09-22 | 2006-03-23 | Mazda Motor Corporation | Exhaust gas purification system |
US20070204602A1 (en) * | 2004-04-05 | 2007-09-06 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas control apparatus and exhaust gas control method for internal combustion engine |
US20080228374A1 (en) * | 2006-11-14 | 2008-09-18 | Denso Corporation | Fuel injection device and adjustment method thereof |
US20100064662A1 (en) * | 2006-06-13 | 2010-03-18 | Volvo Lastvagnar Ab | Diesel catalyst system |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2003232218A (en) * | 2002-02-08 | 2003-08-22 | Hino Motors Ltd | Exhaust emission control device for engine |
JP2004204699A (en) * | 2002-12-24 | 2004-07-22 | Hino Motors Ltd | Exhaust gas purifying device |
JP4013771B2 (en) * | 2003-01-23 | 2007-11-28 | トヨタ自動車株式会社 | Exhaust gas purification device for internal combustion engine |
JP2005098193A (en) * | 2003-09-24 | 2005-04-14 | Toyota Motor Corp | Internal combustion engine with turbocharger, and exhaust emission control device |
JP2005264774A (en) * | 2004-03-17 | 2005-09-29 | Hino Motors Ltd | Controller of exhaust emission control device |
JP2005320880A (en) * | 2004-05-07 | 2005-11-17 | Nissan Diesel Motor Co Ltd | Exhaust emission control device |
JP2006200473A (en) * | 2005-01-21 | 2006-08-03 | Mitsubishi Fuso Truck & Bus Corp | Control device for engine with exhaust gas after-treating device |
-
2006
- 2006-09-21 JP JP2006255634A patent/JP2008075543A/en active Pending
-
2007
- 2007-09-14 US US12/441,412 patent/US20100005787A1/en not_active Abandoned
- 2007-09-14 EP EP07807310A patent/EP2065577A1/en not_active Withdrawn
- 2007-09-14 WO PCT/JP2007/067903 patent/WO2008035623A1/en active Application Filing
Patent Citations (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6347831B1 (en) * | 1999-10-18 | 2002-02-19 | Lifetime Products, Inc. | Foldable picnic table with telescoping pedestals and bench supports |
EP1363009A1 (en) * | 2001-02-20 | 2003-11-19 | Isuzu Motors Limited | Fuel injection control method for diesel engine and regenerative control method for exhaust gas after treatment device |
US20030110761A1 (en) * | 2001-12-13 | 2003-06-19 | Isuzu Motors Limited | Exhaust emission purification system for diesel engine |
US20040200271A1 (en) * | 2003-04-11 | 2004-10-14 | Van Nieuwstadt Michiel J. | Pressure sensor diagnosis via a computer |
US6947831B2 (en) * | 2003-04-11 | 2005-09-20 | Ford Global Technologies, Llc | Pressure sensor diagnosis via a computer |
US20050086933A1 (en) * | 2003-10-27 | 2005-04-28 | Nieuwstadt Michiel V. | Method and system for controlling simultaneous diesel particulate filter regeneration and lean NOx trap desulfation |
US20070204602A1 (en) * | 2004-04-05 | 2007-09-06 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas control apparatus and exhaust gas control method for internal combustion engine |
US20060059900A1 (en) * | 2004-09-22 | 2006-03-23 | Mazda Motor Corporation | Exhaust gas purification system |
US20100064662A1 (en) * | 2006-06-13 | 2010-03-18 | Volvo Lastvagnar Ab | Diesel catalyst system |
US20080228374A1 (en) * | 2006-11-14 | 2008-09-18 | Denso Corporation | Fuel injection device and adjustment method thereof |
Cited By (25)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10646935B2 (en) | 2006-11-28 | 2020-05-12 | The Hillman Group, Inc. | Self service key duplicating machine with automatic key model identification system |
US20110047986A1 (en) * | 2009-08-17 | 2011-03-03 | Drasner Iii Henry Joseph | Retrofit Aftertreatment System for Treating Diesel Exhaust |
US8783022B2 (en) * | 2009-08-17 | 2014-07-22 | Donaldson Company, Inc. | Retrofit aftertreatment system for treating diesel exhaust |
US20110219754A1 (en) * | 2010-03-05 | 2011-09-15 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purification apparatus of an internal combustion engine |
US8677736B2 (en) | 2010-03-05 | 2014-03-25 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purification apparatus of an internal combustion engine |
WO2011152830A1 (en) * | 2010-06-04 | 2011-12-08 | International Engine Intellectual Property Company, Llc | System and method for injecting ammonia into an exhaust gas stream |
US20120117946A1 (en) * | 2010-11-11 | 2012-05-17 | Gm Global Technology Operations, Inc. | Control method and apparatus for regenerating a particulate filter |
US8707684B2 (en) * | 2010-11-11 | 2014-04-29 | GM Global Technology Operations LLC | Control method and apparatus for regenerating a particulate filter |
US20140250168A1 (en) * | 2011-07-14 | 2014-09-04 | Ayodele Damola | Optimization engine in a mobile cloud accelerator and related methods |
US9156000B2 (en) | 2011-09-21 | 2015-10-13 | Hino Motors, Ltd. | Exhaust gas purifier |
CN103827022A (en) * | 2011-09-21 | 2014-05-28 | 日野自动车株式会社 | Exhaust gas purifier |
EP2868882A4 (en) * | 2012-05-31 | 2016-05-18 | Ud Trucks Corp | Method for improving durability of exhaust-gas pipe, and exhaust-gas purification device |
US9657362B2 (en) | 2012-05-31 | 2017-05-23 | Ud Trucks Corporation | Method for improving durability of exhaust pipe |
US20160032802A1 (en) * | 2013-03-18 | 2016-02-04 | Yanmar Co., Ltd. | Exhaust purification system and ship comprising same |
US9394822B2 (en) * | 2013-07-15 | 2016-07-19 | Ford Global Technologies, Llc | Emission control system including an oxidation catalyst and selective catalytic reduction catalyst |
US20150013310A1 (en) * | 2013-07-15 | 2015-01-15 | Ford Global Technology, Llc | Emission control system including an oxidation catalyst and selective catalytic reduction catalyst |
RU2687854C2 (en) * | 2014-02-28 | 2019-05-16 | Юмикор АГ унд Ко. КГ | Method of exhaust gas purification of engine with compression ignition |
US10399036B2 (en) | 2014-02-28 | 2019-09-03 | Umicore Ag & Co. Kg | Method for the cleaning of exhaust gas from a compression ignition engine |
WO2015128247A1 (en) * | 2014-02-28 | 2015-09-03 | Haldor Topsøe A/S | Method for the cleaning of exhaust gas from a compression ignition engine |
CN104454086A (en) * | 2014-12-08 | 2015-03-25 | 山东大学 | DPF (diesel particulate filter) initiative regeneration system with combustor |
US10086332B2 (en) | 2015-05-07 | 2018-10-02 | Ford Global Technologies, Llc | Exhaust flow device |
US9822688B2 (en) | 2015-06-24 | 2017-11-21 | Ford Global Technologies, Llc | Exhaust flow device |
US10066530B2 (en) | 2015-11-17 | 2018-09-04 | Ford Global Technologies, Llc | Exhaust gas mixer |
WO2021071299A1 (en) * | 2019-10-11 | 2021-04-15 | 서울대학교산학협력단 | Exhaust gas post-processing system control device |
US20220298428A1 (en) * | 2019-11-13 | 2022-09-22 | Haldor Topsøe A/S | Halides removal washing system for a hydrocarbon stream |
Also Published As
Publication number | Publication date |
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EP2065577A1 (en) | 2009-06-03 |
WO2008035623A1 (en) | 2008-03-27 |
JP2008075543A (en) | 2008-04-03 |
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Owner name: HINO MOTORS, LTD., JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HOSOYA, MITSURU;KAWADA, YOSHIHIRO;REEL/FRAME:022400/0273 Effective date: 20090224 |
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STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |