US20120079812A1 - Exhaust gas purification apparatus of engine and exhaust gas purification method of engine - Google Patents

Exhaust gas purification apparatus of engine and exhaust gas purification method of engine Download PDF

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Publication number
US20120079812A1
US20120079812A1 US13/314,888 US201113314888A US2012079812A1 US 20120079812 A1 US20120079812 A1 US 20120079812A1 US 201113314888 A US201113314888 A US 201113314888A US 2012079812 A1 US2012079812 A1 US 2012079812A1
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amount
aqueous solution
urea aqueous
exhaust gas
engine
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US13/314,888
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English (en)
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Nobuhiko Masaki
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UD Trucks Corp
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UD Trucks Corp
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Publication of US20120079812A1 publication Critical patent/US20120079812A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
    • 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
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/90—Injecting reactants
    • 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
    • B01D53/9431—Processes characterised by a specific device
    • 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
    • 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
    • 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
    • B01D2251/2067—Urea
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/911—NH3-storage component incorporated in the catalyst
    • 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
    • B01D53/9436—Ammonia
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/14—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust gas
    • F01N2900/1402—Exhaust gas composition
    • 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
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
    • F01N2900/1616—NH3-slip from catalyst
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
    • F01N2900/1622—Catalyst reducing agent absorption capacity or consumption amount
    • 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

Definitions

  • the present invention relates to an exhaust gas purification apparatus of an engine, which selectively reduces a nitrogen oxide (NOx) in exhaust gas by use of ammonia produced from a urea aqueous solution, and an exhaust gas purification method of an engine.
  • NOx nitrogen oxide
  • an exhaust gas purification apparatus As a catalytic purification system which removes NOx included in exhaust gas of an engine, there has been proposed an exhaust gas purification apparatus as disclosed in Japanese Laid-open Patent Application Publication No. 2008-261253.
  • This exhaust gas purification apparatus injection-supplies an ammonia solution with a flow rate in accordance with an engine operation state to the exhaust gas on an exhaust upstream side of a selective catalytic reduction (SCR) catalyst disposed in an engine exhaust pipe, and selectively reduces NOx in the exhaust gas by the SCR catalyst, to convert NOx into harmless components.
  • SCR selective catalytic reduction
  • ammonia which does not reduce NOx in exhaust gas but is adsorbed to an SCR catalyst and ammonia which does not reduce NOx in the exhaust gas but passes through the SCR catalyst and is discharged to the atmosphere are present, depending on an engine operation state.
  • the ammonia which has passed through the SCR catalyst is oxidized by an oxidation catalyst disposed on an exhaust downstream side of the the SCR catalyst, whereby it is possible to suppress the discharging the ammpnia into the atmosphere.
  • the ammonia adsorbed to the SCR catalyst is not taken into consideration, but a flow rate of a urea aqueous solution to be injection-supplied to the exhaust gas on an exhaust upstream side of the SCR catalyst is controlled.
  • an object of one aspect of the present invention is to provide an exhaust gas purification apparatus of an engine which estimates an amount of ammonia adsorbed to an SCR catalyst to control the dosing of a urea aqueous solution in accordance with the estimation result, to achieve the effective utilization of the urea aqueous solution, and an exhaust gas purification method of an engine.
  • an exhaust gas purification apparatus of an engine includes a selective reduction catalyst disposed in an exhaust pipe of the engine to selectively reduce NOx by use of ammonia produced from a urea aqueous solution, an dosing unit which doses the urea aqueous solution to an exhaust gas on an exhaust upstream side of the selective reduction catalyst, and a control unit having a built-in computer.
  • control unit calculates an amount of the produced ammonia from an amount of the dosed urea aqueous solution in accordance with an engine operation state, and calculates a purification ratio of NOx by the selective reduction catalyst on the basis of a first NOx concentration in the exhaust gas discharged from the engine and a second NOx concentration in the exhaust gas passed through the selective reduction catalyst.
  • control unit performs calculation to estimate an amount of the ammonia to be adsorbed to the selective reduction catalyst on the basis of the amount of the produced ammonia and the purification ratio of NOx, and corrects the amount of the urea aqueous solution to be dosed in accordance with the engine operation state on the basis of the amount of the adsorbed ammonia.
  • control unit controls an operation of the dosing unit on the basis of the corrected amount of the urea aqueous solution to be dosed.
  • the control unit calculates a purification ratio of NOx by the selective reduction catalyst on the basis of a first NOx concentration in the exhaust gas discharged from the engine and a second NOx concentration in the exhaust gas passed through the selective reduction catalyst, and performs calculation to estimate an amount of the adsorbed urea aqueous solution corresponding to ammonia to be adsorbed to the selective reduction catalyst on the basis of an amount of the urea aqueous solution to be dosed in accordance with an engine operation state and the purification ratio of NOx.
  • control unit corrects the amount of the urea aqueous solution to be dosed in accordance with the engine operation state on the basis of the amount of the adsorbed urea aqueous solution, and then controls an operation of the dosing unit on the basis of the corrected amount of the urea aqueous solution to be dosed.
  • a control unit corrects an amount of an urea aqueous solution to be dosed in accordance with an engine operation state on the basis of a purification ratio of NOx by a selective reduction catalyst, and doses the corrected amount of the urea aqueous solution to be dosed to an exhaust upstream side of the selective reduction catalyst.
  • an amount of an urea aqueous solution to be dosed in accordance with an engine operation state is thus corrected, so that it is possible to suppress the ammonia passed through the selective reduction catalyst and discharged to the atmosphere, while acquiring the ammonia required for NOx purification by the selective reduction catalyst. In consequence, it is possible to achieve the effective utilization of the urea aqueous solution.
  • FIG. 1 is an overall block diagram showing an example of an exhaust gas purification apparatus which embodies the present invention
  • FIG. 2 is a flowchart showing an example of a control program
  • FIG. 3 is a flowchart showing another example of the control program.
  • FIG. 1 shows an embodiment of an exhaust gas purification apparatus which embodies the present invention.
  • a nitrogen oxidation catalyst 16 which oxidizes nitrogen monoxide (NO) into nitrogen dioxide (NO 2 )
  • an injection nozzle 18 which injection-supplies a urea aqueous solution
  • an SCR catalyst 20 which selectively reduces NOx by use of ammonia produced from the urea aqueous solution
  • an ammonia oxidation catalyst 22 which oxidizes the ammonia passed through the SCR catalyst 20 are arranged in this order along an exhaust flow-through direction.
  • the urea aqueous solution stored in a reducing agent tank 24 is supplied to the injection nozzle 18 through a reducing agent dosing unit 26 having a built-in pump and a built-in flow rate control valve therein. It is to be noted that the injection nozzle 18 , the reducing agent tank 24 and the reducing agent dosing unit 26 are included to constitute an example of a dosing unit.
  • the reducing agent dosing unit 26 may have a constitution which is divided into a pump module having the built-in pump, and a dosing module having the built-in flow rate control valve.
  • a NOx sensor 28 which measures a NOx concentration Cu in exhaust gas discharged from the engine 10 is attached.
  • a NOx sensor 30 which measures a NOx concentration Cd in the exhaust gas passed through the ammonia oxidation catalyst 22 is attached.
  • an exhaust temperature sensor 32 which measures a temperature (an exhaust temperature) T of the exhaust gas flowing into the SCR catalyst 20 is attached to. It is to be noted that in an exhaust gas purification apparatus in which the ammonia oxidation catalyst 22 is not disposed, the NOx sensor 30 measures the NOx concentration Cd in the exhaust gas passed through the SCR catalyst 20 .
  • Each measurement signal of the NOx sensors 28 and 30 and the exhaust temperature sensor 32 is input into a reducing agent dosing control unit 34 having a built-in computer. Moreover, the reducing agent dosing control unit 34 is connected to an engine control unit 36 which electronically controls the engine 10 via a controller area network (CAN) and the like so that a rotation speed Ne and a load Q can appropriately be read as an engine operation state.
  • CAN controller area network
  • the load Q of the engine 10 for example, a fuel injection amount, an intake air flow, an intake air pressure, a supercharging pressure, an accelerator open degree, a throttle open degree or the like can be applied.
  • the rotation speed Ne and load Q of the engine 10 are not limited to a constitution to be read from the engine control unit 36 , but may directly be measured by a known sensor.
  • the reducing agent dosing control unit 34 executes a control program stored in a read only memory (ROM) or the like, to electronically control the reducing agent dosing unit 26 so that the ammonia is supplied to the SCR catalyst 20 in accordance with the engine operation state.
  • ROM read only memory
  • the urea aqueous solution injection-supplied (dosed) through the injection nozzle 18 is hydrolyzed by using exhaust heat and vapor in the exhaust gas, and is converted into ammonia which functions as a reducing agent. It is known that this ammonia selectively reduces NOx in the exhaust gas in the SCR catalyst 20 , and is converted into harmless water (H 2 O) and nitrogen (N 2 ). At this time, NO is oxidized to NO 2 in the nitrogen oxidation catalyst 16 to enhance a NOx purification ratio by the SCR catalyst 20 , whereby a ratio between NO and NO 2 in the exhaust gas is improved to be suitable for the selective reductive reaction.
  • the ammonia passed through the SCR catalyst 20 is oxidized through the ammonia oxidation catalyst 22 disposed on the exhaust downstream side the SCR catalyst 20 , so that the ammonia is prevented from being discharged as it is to the atmosphere.
  • FIG. 2 shows an example of a control program to be executed by the reducing agent dosing control unit 34 with the start of the engine 10 as an opportunity.
  • step 1 (abbreviated as “S 1 ” in the drawings. This also applies to the following description.)
  • the reducing agent dosing control unit 34 reads, as the engine operation state, the exhaust temperature T from the exhaust temperature sensor 32 and the rotation speed Ne and the load Q from the engine control unit 36 .
  • the reducing agent dosing control unit 34 calculates an amount of the urea aqueous solution to be dosed in accordance with the engine operation state.
  • the reducing agent dosing control unit 34 refers to a control map in which the amount of the dosed urea aqueous solution adapted to the exhaust temperature, the rotation speed and the load is set, to obtain the amount of the urea aqueous solution to be dosed in accordance with the exhaust temperature T, the rotation speed Ne and the load Q.
  • step 3 the reducing agent dosing control unit 34 electronically controls each of the pump and flow rate control valve of the reducing agent dosing unit 26 , in accordance with the amount of the urea aqueous solution to be dosed so that the urea aqueous solution is injection-supplied through the injection nozzle 18 in accordance with the engine operation state.
  • step 4 the reducing agent dosing control unit 34 calculates an amount of the produced ammonia from the amount of the dosed urea aqueous solution, by use of a condition that two mols of ammonia is produced from one mol of urea.
  • step 5 the reducing agent dosing control unit 34 reads the NOx concentrations Cu and Cd from the NOx sensors 28 and 30 , respectively.
  • step 6 the reducing agent dosing control unit 34 calculates the NOx purification ratio by the SCR catalyst 20 by use of an equation “NOx purification ratio equals NOx concentration Cu minus NOx concentration Cd divided by NOx concentration Cu”.
  • the reducing agent dosing control unit 34 perform calculation to estimate an amount of the ammonia to be adsorbed to the SCR catalyst 20 by use of an equation “the amount of the adsorbed ammonia equals the amount of the produced ammonia multiplied by 1 minus NOx purification ratio, both terms in the parentheses”.
  • the reducing agent dosing control unit 34 presumes that the urea aqueous solution which does not contribute to the NOx purification in the urea aqueous solution injection-supplied through the injection nozzle 18 has been adsorbed to the SCR catalyst 20 in ammonia state.
  • step 8 the reducing agent dosing control unit 34 reads, as the engine operation state, the exhaust temperature T from the exhaust temperature sensor 32 and the rotation speed Ne and the load Q from the engine control unit 36 .
  • step 9 the reducing agent dosing control unit 34 calculates the amount of the urea aqueous solution to be dosed in accordance with the engine operation state by a method similar to the step 2 .
  • step 10 the reducing agent dosing control unit 34 calculates the amount of the urea aqueous solution corresponding to the amount of the adsorbed ammonia estimated in the step 7 , by use of a condition that one mol of ammonia is produced from 1 ⁇ 2 mol of urea.
  • step 11 the reducing agent dosing control unit 34 subtracts the amount of the urea aqueous solution from the amount of the dosed urea aqueous solution, to correct the amount of the urea aqueous solution to be dosed. That is, it is noted that the ammonia adsorbed to the SCR catalyst 20 is utilized for the purification of NOx in the exhaust gas, and thus, the reducing agent dosing control unit 34 decreases the amount of the urea aqueous solution to be dosed. Then, upon the completion of the correction of the amount of the urea aqueous solution to be dosed, the reducing agent dosing control unit 34 returns the processing to the step 3 .
  • the amount of the urea aqueous solution to be dosed in accordance with the engine operation state is dosed to the exhaust upstream of the SCR catalyst 20 .
  • the purification ratio of NOx to be selectively reduced by the SCR catalyst 20 is obtained on the basis of the NOx concentration in the exhaust gas discharged from the engine 10 and the NOx concentration in the exhaust gas passed through the ammonia oxidation catalyst 22 .
  • an amount represented by “1-NOx purification ratio” is the amount of the ammonia to be adsorbed to the SCR catalyst 20 .
  • the amount of the urea aqueous solution corresponding to the amount of the adsorbed ammonia is subtracted from the amount of the urea aqueous solution to be dosed in accordance with the engine operation state to correct the amount of the urea aqueous solution to be dosed, and on the basis of the corrected amount of the urea aqueous solution to be dosed, the dosing of the urea aqueous solution is controlled.
  • the amount of the urea aqueous solution to be dosed in accordance with the engine operation state is corrected on the basis of the NOx purification ratio by the SCR catalyst 20 , and the corrected amount of the urea aqueous solution to be dosed is dosed to the exhaust gas on the exhaust upstream side of the SCR catalyst 20 .
  • the amount of the urea aqueous solution to be dosed in accordance with the engine operation state is thus decreased and corrected. Therefore, the ammonia passed through the SCR catalyst 20 and discharged to the atmosphere can be suppressed, while acquiring the ammonia required for the NOx purification by the SCR catalyst 20 . In consequence, the effective utilization of the urea aqueous solution can be achieved. Moreover, the amount of the ammonia which is not adsorbed to the SCR catalyst 20 but is introduced into the ammonia oxidation catalyst 22 decreases. Therefore, the ammonia oxidation catalyst 22 can be miniaturized, and the decrease of a weight and cost thereof can be expected.
  • FIG. 3 shows another example of the control program to be executed by the reducing agent dosing control unit 34 with the start of the engine 10 as the opportunity.
  • the description of the processing which is common to the control program shown in FIG. 2 is simplified for a purpose of excluding redundant description.
  • step 21 the reducing agent dosing control unit 34 reads, as the engine operation state, the exhaust temperature T from the exhaust temperature sensor 32 and the rotation speed Ne and the load Q from the engine control unit 36 .
  • step 22 the reducing agent dosing control unit 34 calculates the amount of the urea aqueous solution to be dosed in accordance with the engine operation state.
  • step 23 the reducing agent dosing control unit 34 electronically controls each of the pump and flow rate control valve of the reducing agent dosing unit 26 , in accordance with the amount of the urea aqueous solution to be dosed.
  • step 24 the reducing agent dosing control unit 34 reads the NOx concentrations Cu and Cd from the NOx sensors 28 and 30 , respectively.
  • step 25 the reducing agent dosing control unit 34 calculates the NOx purification ratio by the SCR catalyst 20 by use of the equation “NOx purification ratio equals NOx concentration Cu minus NOx concentration Cd divided by NOx concentration Cu”.
  • step 26 the reducing agent dosing control unit 34 perform calculation to estimate the amount of the adsorbed urea aqueous solution corresponding to the amount of the ammonia to be adsorbed to the SCR catalyst 20 by use of an equation “the amount of the adsorbed urea aqueous solution equals the amount of the dosed urea aqueous solution multiplied by 1-NOx purification ratio, both terms in the parentheses”.
  • step 27 the reducing agent dosing control unit 34 reads, as the engine operation state, the exhaust temperature T from the exhaust temperature sensor 32 and the rotation speed Ne and the load Q from the engine control unit 36 .
  • step 28 the reducing agent dosing control unit 34 calculates the amount of the urea aqueous solution to be dosed in accordance with the engine operation state.
  • step 29 the reducing agent dosing control unit 34 subtracts the amount of the adsorbed urea aqueous solution from the amount of the dosed urea aqueous solution, to correct the amount of the urea aqueous solution to be dosed. Afterward, the unit returns the processing to the step 23 .
  • the amount of the urea aqueous solution to be dosed is corrected on the basis of the urea aqueous solution, so that the control can be simplified.
  • the amount of the adsorbed ammonia or the amount of the adsorbed urea aqueous solution corresponding thereto may be corrected on the basis of an ammonia concentration measured by an ammonia sensor attached to the exhaust pipe 14 positioned on the exhaust downstream side of the ammonia oxidation catalyst 22 .
  • the amount of the adsorbed ammonia or the amount of the adsorbed urea aqueous solution is obtained in consideration of the amount of the ammonia passed through the ammonia oxidation catalyst 22 , and hence control accuracy can be enhanced.
  • the effective utilization of the urea aqueous solution can further be promoted through the enhancement of the control accuracy.
  • the ammonia sensor measures the concentration of the ammonia in the exhaust gas passed through the SCR catalyst 20 .
  • the present invention can be applied to an exhaust gas purification apparatus including the exhaust pipe 14 further provided with a diesel particulate filter (DPF) which collects and removes a particulate matter (PM), an exhaust gas purification apparatus including the DPF coated with a catalyst component which functions as an SCR catalyst, and the like.
  • DPF diesel particulate filter
  • PM particulate matter

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Environmental & Geological Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Biomedical Technology (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • General Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Toxicology (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
US13/314,888 2009-06-18 2011-12-08 Exhaust gas purification apparatus of engine and exhaust gas purification method of engine Abandoned US20120079812A1 (en)

Applications Claiming Priority (3)

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JP2009145276A JP5398372B2 (ja) 2009-06-18 2009-06-18 エンジンの排気浄化装置
JP2009-145276 2009-06-18
PCT/JP2010/060092 WO2010147107A1 (ja) 2009-06-18 2010-06-15 エンジンの排気浄化装置及び排気浄化方法

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US20150068197A1 (en) * 2013-09-10 2015-03-12 GM Global Technology Operations LLC Urea injection controller for a motorized system
US9429061B2 (en) 2012-07-04 2016-08-30 Emitec Gesellschaft Fuer Emissionstechnologie Mbh Method for metering a reducing agent into an exhaust-gas treatment device, exhaust-gas treatment device and motor vehicle
CN106121797A (zh) * 2016-08-29 2016-11-16 无锡威孚力达催化净化器有限责任公司 Scr后处理系统氨泄漏状态判断方法
CN112240235A (zh) * 2019-07-17 2021-01-19 上海汽车集团股份有限公司 一种scr的控制方法及装置
US11359531B2 (en) * 2019-07-26 2022-06-14 GM Global Technology Operations LLC Method for control of exhaust aftertreatment for diesel engine

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