CN109854347A - Method for calibration model ammonia fill level - Google Patents
Method for calibration model ammonia fill level Download PDFInfo
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- CN109854347A CN109854347A CN201811444942.3A CN201811444942A CN109854347A CN 109854347 A CN109854347 A CN 109854347A CN 201811444942 A CN201811444942 A CN 201811444942A CN 109854347 A CN109854347 A CN 109854347A
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- downstream
- scr
- scr catalyst
- mass flow
- fill level
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 title claims abstract description 146
- 229910021529 ammonia Inorganic materials 0.000 title claims abstract description 73
- 238000000034 method Methods 0.000 title claims abstract description 26
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims abstract description 135
- 239000003054 catalyst Substances 0.000 claims abstract description 117
- 238000006555 catalytic reaction Methods 0.000 claims abstract description 21
- 239000007789 gas Substances 0.000 claims abstract description 17
- 230000000052 comparative effect Effects 0.000 claims abstract 2
- 230000008859 change Effects 0.000 claims description 8
- 238000004590 computer program Methods 0.000 claims description 8
- DOTMOQHOJINYBL-UHFFFAOYSA-N molecular nitrogen;molecular oxygen Chemical compound N#N.O=O DOTMOQHOJINYBL-UHFFFAOYSA-N 0.000 claims description 4
- 150000001875 compounds Chemical class 0.000 claims 3
- 238000011144 upstream manufacturing Methods 0.000 description 14
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- 239000003638 chemical reducing agent Substances 0.000 description 7
- 238000002485 combustion reaction Methods 0.000 description 7
- 239000003795 chemical substances by application Substances 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 238000005915 ammonolysis reaction Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 239000004202 carbamide Substances 0.000 description 2
- 238000010531 catalytic reduction reaction Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 230000004913 activation Effects 0.000 description 1
- 230000003044 adaptive effect Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 235000012771 pancakes Nutrition 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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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
-
- 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
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/2066—Selective catalytic reduction [SCR]
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N9/00—Electrical control of exhaust gas treating apparatus
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N9/00—Electrical control of exhaust gas treating apparatus
- F01N9/005—Electrical control of exhaust gas treating apparatus using models instead of sensors to determine operating characteristics of exhaust systems, e.g. calculating catalyst temperature instead of measuring it directly
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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
- F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
- F01N2550/02—Catalytic activity of catalytic converters
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
- F01N2560/02—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor
- F01N2560/026—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor for measuring or detecting NOx
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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
-
- 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
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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
- 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
- F01N2900/1621—Catalyst conversion efficiency
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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
- 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
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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
Abstract
The present invention relates to a kind of methods for correcting the modelling ammonia fill level of the downstream SCR catalyst (22) in SCR catalysis system (20), and there are two the SCR catalysts (21,22) being arranged successively in gas exhaust piping (11) for SCR catalysis system tool.The nitrogen oxide mass flow that the expection nitrogen oxide mass flow in downstream SCR catalyst (22) downstream measures at the downstream in downstream SCR catalyst (22) is compared.It is corrected based on comparative result.
Description
Technical field
The present invention relates to a kind of for correcting the modelling of the downstream SCR catalyst in SCR catalysis system
(modelliert) there are two SCR being arranged successively in gas exhaust piping to urge for the method for ammonia fill level, the SCR catalysis system
Change device.Moreover, it relates to execute the computer program of each step of this method, and store the computer program
Machine readable storage medium.Finally, being arranged for executing this method the present invention relates to a kind of control electronics.
Background technique
By ammonia or the selective catalytic reduction of ammonolysis agent (Selective Catalytic Reduction;SCR) it is
Reduce the promising method of the nitrogen oxides in oxygen-rich exhaust.The efficiency of SCR catalyst depends on the space of its temperature, exhaust gas
Speed and key are the fill levels of the ammonia depending on its adsorption.Other than the ammonia of direct dispensing, adsorbed ammonia
Also for nitrogen oxides reduction, as a result, relative to the catalyst converter of emptying, the efficiency of SCR catalyst is improved.Storage performance depends on
The corresponding running temperature of catalyst converter.Temperature is lower, and storage capacity is bigger.
If SCR catalyst is filled up completely its reservoir, occur in the internal combustion engine for restoring its exhaust gas by SCR catalyst negative
When carrying transition, even if also resulting in ammonia evolution without ammonia or ammonolysis agent with being given in gas exhaust piping.But it if to realize to the greatest extent
Possible high transformation efficiency of the oxides of nitrogen, just inevitably needs to run SCR system under high ammonia fill level.If due to internal combustion
The temperature of the load transient of machine, fully filled SCR catalyst increases, then the ammonia storage capacity decline of the SCR catalyst, thus
Ammonia is caused to escape.
SCR catalyst is mounted near internal combustion engine, therefore SCR catalyst is rapidly reached its fortune after internal combustion engine cold start-up
Trip temperature, thus above-mentioned effect is with regard to particularly significant.Therefore, can be arranged in gas exhaust piping in the downstream of the first SCR catalyst
Second SCR catalyst, for adsorbing ammonia from the evolution of the ammonia of the first catalyst converter and then being converted.
The criterion calls of onboard diagnostic system (OBD) must monitor two SCR catalysts.For this purpose, usually being urged in two SCR
The downstream for changing device is respectively present NOx sensor.For cost reasons, usually only in the first SCR catalyst upstream, installation is matched
Valve is measured, ammonolysis reducing agent solution is matched and is given in gas exhaust piping.The ammonia filling of the second SCR catalyst only passes through first as a result,
The ammonia of SCR catalyst, which escapes, to carry out.However, it is also possible to arrange other metering valve between SCR catalyst.The data of sensor
It can be used for modeling the fill level of two SCR catalysts.
However, it may occur that the ammonia fill level of the physics in second or downstream SCR catalyst deviates modelling
Ammonia fill level.When the ammonia fill level of physics is too low, the transformation efficiency of the oxides of nitrogen of the second SCR catalyst is reduced and just
It may cause over-limit condition.Although the method for rapidly adapting to can re-calibrate the nitrogen oxides volume in the second SCR catalyst downstream
Definite value, but still be difficult to eliminate source of error because adaptive method can not determination should be in the region of the first SCR catalyst still
Source of error is found in the region of two SCR catalysts.
Summary of the invention
This method is used to correct the modelling ammonia fill level of the downstream SCR catalyst in SCR catalysis system, which urges
Change system has two SCR catalysts being arranged successively in gas exhaust piping.Here, upstream SCR catalyst is close to internal combustion engine, and
Outlet of the downstream SCR catalyst close to gas exhaust piping.By the expection nitrogen oxide mass flow in downstream SCR catalyst downstream with
The nitrogen oxide mass flow measured at the downstream of downstream SCR catalyst compares.Result is corrected based on this comparison.
In traditional operation reserve, there are two specified fill levels for upstream SCR catalyst tool.Minimum specified fill level is led
The poor efficiency of SCR reaction is caused, but ammonia evolution does not occur.Still it is being regarded as proper ammonia evolution (especially no more than 200ppm)
Under conditions of, maximum rated fill level leads to high transformation efficiency of the oxides of nitrogen.Upstream SCR is run first under maximum fill level
Catalyst converter, SCR efficiency is very high, and the ammonia evolution generated is received by downstream SCR catalyst.Occurring from upstream catalyst
In the case that low NOx evolution but high ammonia escape, under the ammonia fill level in downstream SCR catalyst rises rapidly and is more than
Swim the specified fill level of minimum of SCR catalyst.The specified fill level of minimum of downstream SCR catalyst just has been provided for high nitrogen oxygen
Compound conversion ratio, but still there is the fill volume for the ammonia evolution from upstream SCR catalyst.If in downstream SCR catalyst
Ammonia fill level be higher than minimum specified fill level and be lower than maximum rated fill level, then reduced corresponding to interpolation factor
Swim the specified fill level of ammonia in SCR catalyst.If the fill level in the second SCR catalyst rise to maximum fill level or
Higher, then the specified fill level of ammonia in the SCR catalyst of upstream is reduced to minimum fill level.In downstream SCR catalyst most
Big specified fill level is defined herein as, and is disposed in the normal operation of the motor vehicles of SCR catalysis system in gas exhaust piping,
Do not occur from downstream SCR catalyst or only occur slight ammonia evolution.If except the dosage positioned at the upstream of upstream SCR catalyst
Except valve, SCR catalysis system also has the other metering valve between SCR catalyst, then will be in downstream SCR catalyst
Ammonia fill level is at least maintained at its minimum specified fill level.This (causes high ammonia storage to be held in upstream SCR catalyst low temperature
Amount) under conditions of, it is impossible without the second metering valve.
When the deviation of the model of the ammonia fill level of downstream SCR catalyst is practical, such as downstream SCR catalyst may cause
Ammonia fill level reduced during the boost phase of motor vehicles.The situation can be prevented by correcting.Downstream SCR catalysis
The expection nitrogen oxide mass flow in device downstream preferably by between two SCR catalysts nitrogen oxide mass flow and downstream
The efficiency of SCR catalyst determines.Here, the efficiency is obtained by the model of downstream SCR catalyst, so as to recognize mistake
Model value.Nitrogen oxide mass flow between two SCR catalysts is preferably measured by NOx sensor.In addition,
There is ammoniacal sensor between SCR catalyst, preferably in order to which one side can be measured into the ammonia acquisition amount in downstream SCR catalyst
And the ammonia acquisition amount can be passed to catalyst converter model, it on the other hand can compensate for the ammonia cross sensitivity of NOx sensor
Property (Ammoniakquerempfindlichkeit).But in principle, the nitrogen oxide mass flow between two SCR catalysts
It can also be obtained respectively by respective model with ammonia mass flow.
It in an embodiment of this method, is thus corrected, that is, in the common adjusting to two SCR catalysts
In, change SCR catalysis in downstream according to the difference between expected nitrogen oxide mass flow and the nitrogen oxide mass flow measured
The current ammonia fill level of device.Under high catalyst temperature, downstream SCR catalyst is for a long time almost only by coming from upstream SCR
The ammonia evolution of catalyst converter supplies at once, and when metering valve that may be present between two SCR catalysts is hardly in use, above-mentioned
Scheme is exactly particularly preferred.
It in another embodiment of this method, is thus corrected, that is, in the common adjusting to two SCR catalysts
In, according to the difference between expected nitrogen oxide mass flow and the nitrogen oxide mass flow measured, measured with correcting value change
Nitrogen oxide mass flow value.
In two embodiments of this method, it is preferably carried out adjusting, that is, the ammonia of downstream SCR catalyst fills water
It is flat relative to the predetermined ammonia fill level depending on temperature at most deviate can predetermined threshold value, it is predetermined at this
The ammonia fill level depending on temperature under, there is no ammonia evolution at downstream catalyst.In the tradition operation plan of SCR catalysis system
In slightly, which is the maximum rated fill level of downstream SCR catalyst.
Each step that computer program executes this method is set, especially when the computer program is calculating equipment or electricity
When being run in son control equipment.For this purpose, the computer program is stored on machine readable storage medium.
By running the computer program on control electronics, just obtains and be arranged for being corrected down by this method
Swim the control electronics of the modelling ammonia fill level of SCR catalyst.
Detailed description of the invention
Shown in the drawings of the embodiment of the present invention, it is further elaborated in next explanation.
Fig. 1 schematically shows SCR catalysis system according to prior art, wherein can be by reality according to the present invention
Apply the modelling ammonia fill level of the method correction downstream SCR catalyst of example.
Fig. 2 shows the time plots of the nitrogen oxide mass flow in SCR catalysis system.
Fig. 3 shows another curve graph of the nitrogen oxide mass flow in SCR catalysis system.
Fig. 4 shows another curve graph of the nitrogen oxide mass flow in SCR catalysis system.
Specific embodiment
Internal combustion engine 10 has SCR catalysis system 20 in its gas exhaust piping 11, as shown in Figure 1.The SCR catalysis system has
Aqueous solution of urea can be sprayed into gas exhaust piping 11 using the first reducing agent metering unit by the first reducing agent metering unit 41.
At a high temperature of exhaust gas, ammonia is released from the aqueous solution of urea.The downstream of first reducing agent metering unit 41 is provided with
One or upstream SCR catalyst 21 and second or downstream SCR catalyst 22.The catalyst material of first SCR catalyst is arranged in
(SCR on filter on particulate filter;SCRF).Upstream arrangement of first NOx sensor 31 in reducing agent metering unit 41
In gas exhaust piping 11.Second NOx sensor 32 is arranged between two SCR catalysts 21,22.Third NOx sensor arrangement
In the downstream of the second SCR catalyst 22.The second reduction is disposed between the second NOx sensor 32 and the second SCR catalyst 22
Agent metering unit 42.Its signal is all passed to control electronics 50 by all NOx sensors 31,32,33.Since NOx is passed
It reacts to ammonia to 31,32,33 cross sensitivity of sensor, their signal is the summation signals of nitrogen oxides and ammonia.But it is restoring
The upstream arrangement of agent metering unit 21 has the first NOx sensor, reliably to measure the amount of the nitrogen oxides in exhaust gas.If
SCR catalysis system 20 is run in this way, i.e., ammonia evolution does not occur at the second SCR catalyst 22, then can be based on this, the 3rd NOx
The signal of sensor is based only upon nitrogen oxides.However, being made since ammonia evolution can be set at the first SCR catalyst 21 with this
For the supplement of the second reducing agent metering unit 42, ammonia is supplied to the second SCR catalyst 22, therefore the second NOx sensor is possible to
Summation signals from ammonia and nitrogen oxides are provided.In order to obtain between two SCR catalysts 21,22 as unit of ppm
Nitrogen oxide mass flow q32, therefore must just reduce the ammonia mass flow in summation signals as unit of ppm.This can be by
The model of first SCR catalyst is determined by the ammoniacal sensor (not shown) between two SCR catalysts.Reducing agent dosage
Amount with the ammonia being given in gas exhaust piping 11 is equally transmitted to control equipment 50 by unit 41,42.
Fig. 2 shows in the operation reserve of SCR catalysis system 20, song of the nitrogen oxide mass flow q about time t
Line.Nitrogen oxide mass flow q32 between two SCR catalysts 21,22 is determined by the signal of the second NOx sensor 32.The
The nitrogen oxide mass flow q33 in two SCR catalysts, 22 downstream is determined by third NOx sensor 33.Qmax is indicated when second
When SCR catalyst is filled with the ammonia of its maximum rated fill level, the expection nitrogen oxidation substance in 22 downstream of the second SCR catalyst
Measure flow.Qmin100 indicates that the 3rd NOx is passed when the second SCR catalyst 22 100% filled with its minimum specified fill level
Expection nitrogen oxide mass flow at sensor 33.Qmin50 indicates only to correspond to when the ammonia fill level of the second SCR catalyst
Its minimum specified fill level 50% when, the expection nitrogen oxide mass flow in 22 downstream of the second SCR catalyst.It is expected that nitrogen
Oxide mass flow qmax, qmin100, qmin50 by nitrogen oxide mass flow 32 and the second SCR catalyst 22 efficiency
It determines.The standardization face of the temperature of activation energy, the second SCR catalyst 22 that the efficiency is reacted by SCR, the second SCR catalyst 22
Product coefficient, the coefficient of frequency of SCR reaction, the specified fill level of minimum ammonia of the second SCR catalyst 22, its maximum ammonia storage capacity
It is obtained with the residence time of SCR catalyst 22.As can be seen that the nitrogen oxide mass flow q33 measured substantially corresponds to needle
To the expection nitrogen oxide mass flow qmin100 of the specified fill level of minimum of downstream SCR catalyst 22.It is catalyzed in SCR and is
Under the operating status of system, wherein the ammonia fill level of downstream SCR catalyst 22 should be adjusted to its minimum specified fill level, survey
This curve of the nitrogen oxide mass flow q33 obtained shows that SCR catalysis system is ideally adjusted and the 2nd SCR is catalyzed
The ammonia fill level of device 22 corresponds to its modelling value.It does not need to be corrected herein.
It is shown in FIG. 3, how the ammonia fill level of the second SCR catalyst gradually leaks under the high load capacity of internal combustion engine 10
To the greatest extent (leerlaufen).From the minimum for being directed to the second SCR catalyst 22 corresponding to expected nitrogen oxide mass flow qmin100(
The 100% of specified fill level) value start, the nitrogen oxide mass flow q33 measured is gradually decreased down specified to be filled out for minimum
50% flat value qmin50 of water-filling.In an embodiment of the method in accordance with the present invention, this trend can thus be stopped, that is, by
The nitrogen oxide mass flow q33 measured identifies calibration model ammonia with the difference for being expected nitrogen oxide mass flow qmin100
The necessity of fill level, and the ammonia fill level in the second SCR catalyst 22 is kept by correcting value.
Fig. 4 is shown, when filling out ammonia fill level from maximum rated by the adjusting intervention in the second SCR catalyst 22
When water-filling pancake is as low as minimum specified fill level, in the nitrogen oxide mass flow q33 that 22 downstream of the second SCR catalyst measures
How to change.Exist to adjust herein and intervene, negative correction can be set in an embodiment of the method in accordance with the present invention for it
Amount.
Claims (8)
1. the method for the modelling ammonia fill level for correcting the downstream SCR catalyst (22) in SCR catalysis system (20), institute
Stating SCR catalysis system has two SCR catalysts (21,22) being arranged successively in gas exhaust piping (11), which is characterized in that will
The expection nitrogen oxide mass flow (qmin100) in downstream SCR catalyst (22) downstream in the downstream SCR catalyst (22)
Downstream at the nitrogen oxide mass flow (q33) that measures compare, and be corrected based on comparative result.
2. the method according to claim 1, wherein the expection nitrogen oxygen in the downstream SCR catalyst (22) downstream
Compound mass flow (qmin100) by between described two SCR catalysts (21,22) nitrogen oxide mass flow (32) and institute
The efficiency for stating downstream SCR catalyst (22) determines.
3. method according to claim 1 or 2, which is characterized in that thus correction carries out, that is, urge to described two SCR
Change in the common adjusting of device (21,22), according to the expected nitrogen oxide mass flow (qmin100) and the nitrogen oxygen measured
Difference between compound mass flow (q33) changes the current ammonia fill level of the downstream SCR catalyst (22).
4. method according to claim 1 or 2, which is characterized in that thus correction carries out, that is, urge to described two SCR
Change in the common adjusting of device (21,22), according to the expected nitrogen oxide mass flow (qmin100) and the nitrogen oxygen measured
Difference between compound mass flow (q33), with correcting value change described in the value of nitrogen oxide mass flow that measures.
5. the method according to claim 3 or 4, which is characterized in that be adjusted in this way, that is, the downstream SCR catalyst
(22) ammonia fill level at most deviates relative to the predetermined ammonia fill level depending on temperature can predetermined threshold
Value, under the predetermined ammonia fill level depending on temperature, there is no ammonia evolutions at the downstream catalyst.
6. computer program is arranged for carrying out each step of the method according to any one of claims 1 to 5.
7. machine readable storage medium, computer program storage according to claim 6 is on said storage.
8. control electronics (50) are arranged for correcting down by the method according to any one of claims 1 to 5
Swim the modelling ammonia fill level of SCR catalyst (23).
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| CN112727577A (en) * | 2019-10-28 | 2021-04-30 | 罗伯特·博世有限公司 | Method for adapting the dosing of a reducing agent in an SCR catalyst |
| CN114263521A (en) * | 2021-12-31 | 2022-04-01 | 潍柴动力股份有限公司 | Sensor parameter correction method and device |
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| GB2589150B (en) * | 2019-11-25 | 2022-02-23 | Delphi Automotive Systems Lux | Dual SCR system control method |
| EP4095362B1 (en) * | 2021-05-26 | 2024-05-01 | Volvo Truck Corporation | Controlling urea injection in exhaust aftertreatment systems |
| CN115095410B (en) * | 2022-07-14 | 2023-11-17 | 潍柴动力股份有限公司 | Control method, control device and control system for tail gas treatment |
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| KR20190064468A (en) | 2019-06-10 |
| DE102017221573A1 (en) | 2019-06-06 |
| CN109854347B (en) | 2022-04-15 |
| KR102660647B1 (en) | 2024-04-26 |
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