CN109642485A - Method for the quality control of reducing agent solution in SCR catalyst - Google Patents

Method for the quality control of reducing agent solution in SCR catalyst Download PDF

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Publication number
CN109642485A
CN109642485A CN201780051768.3A CN201780051768A CN109642485A CN 109642485 A CN109642485 A CN 109642485A CN 201780051768 A CN201780051768 A CN 201780051768A CN 109642485 A CN109642485 A CN 109642485A
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quality
ammonia
mnh
reducing agent
modelling
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CN109642485B (en
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C.海曼
T.普菲斯特
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Robert Bosch GmbH
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Robert Bosch GmbH
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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
    • 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
    • F01N2900/04—Methods of control or diagnosing
    • F01N2900/0412—Methods of control or diagnosing using pre-calibrated maps, tables or charts
    • 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
    • F01N2900/04—Methods of control or diagnosing
    • F01N2900/0418—Methods of control or diagnosing using integration or an accumulated value within an elapsed period
    • 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
    • F01N2900/1411—Exhaust gas flow rate, e.g. mass flow rate or volumetric flow rate
    • 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
    • F01N2900/1621—Catalyst conversion efficiency
    • 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
    • F01N2900/18—Parameters used for exhaust control or diagnosing said parameters being related to the system for adding a substance into the exhaust
    • F01N2900/1806—Properties of reducing agent or dosing system
    • F01N2900/1818—Concentration of the reducing agent
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • 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]
    • 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

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

The present invention relates to a kind of methods, are used for the quality control of the reducing agent solution of SCR catalyst, which includes nitrogen oxides adjuster.In the beginning of this method, SCR catalyst is adjusted to scheduled transformation efficiency of the oxides of nitrogen.Then, the progress integral operation of actual ammonia mass flow is obtained into actual ammonia quality, and the ammonia mass flow of modelling is subjected to the ammonia quality that integral operation is modeled.Then the calculating of dosage quality factor is carried out, it is the quotient of the ammonia quality of actual ammonia quality and modelling, finally, when the dosage factor (facDos) is more than first threshold (311) of setting (at point 312), malfunction is generated, which is attributed to the poor quality of reducing agent solution.

Description

Method for the quality control of reducing agent solution in SCR catalyst
Technical field
The present invention relates to a kind of method, it is used for the quality control of the reducing agent solution in SCR catalyst, SCR catalysis Device has nitrogen oxides adjuster.Moreover, it relates to which a kind of computer program, executes when running on the computing device Each step according to the method for the present invention, and be related to storing the machine readable storage medium of the computer program.Finally, this hair It is bright to be related to a kind of control electronics, it is arranged for executing according to the method for the present invention.
Background technique
Now mainly using SCR catalyst (Selective Catalytic REduction selective catalytic reduction) come Restore the nitrogen oxides (NOx) in motor vehicle exhausts.Here, there are ammonia (NH3) as in the case where reducing agent, it is located at Nitrogen oxides molecule on SCR catalyst surface is reduced into elemental nitrogen.Reducing agent is provided in the form of aqueous solution of urea, wherein Ammonia is dissociated, commercially also referred to as AdBlue®, and reducing agent is injected into exhaust by the dosage module of SCR catalyst upstream Pipeline.The determination of desired dosage ratio carries out in control electronics, has in the control electronics for grasping Make and monitor the strategy of SCR system.
The SCR catalyst being currently known is in its catalyst converter surface storage ammonia.Memory capacity depends primarily on catalyst converter surface Temperature, and reduce as the temperature rises.It is attached to catalyst converter surface and the ammonia that can be used for restoring is more, nitrogen oxidation Object conversion ratio is higher.As long as the memory capacity of SCR catalyst does not exhaust, the reducing agent of excessive dispensing will be stored.On the contrary, such as The reducing agent that fruit metering unit is supplied less than reducing agent needed for nitrogen oxides present in reduction exhaust gas completely, then due to Continue that the reduction of nitrogen oxides occurs and makes the reduction of ammonia fill level in catalyst converter surface.It is commonly used in matching for SCR system at present Amount strategy include fill level adjust, adjust SCR catalyst in using the rated value of ammonia fill level as the operating point of form. The work range selection is to keep ammonia fill level sufficiently high, has not only been enough to ensure that high transformation efficiency of the oxides of nitrogen, but also is enough to provide buffering, To cope with emergent excessive nitrogen oxide mass (so-called nitrogen oxides peak value).It on the other hand, can according to SCR catalyst Ammonia fill level is selected with the maximum ammonia quality of storage.It was especially avoided at temperature quickly raised situation as a result, The ammonia for measuring dispensing without utilizing passes through catalyst converter surface；This is also referred to as ammonia evolution.
The quality definition of aqueous solution of urea is therefrom to dissociate the quotient of the urea quality of ammonia and the gross mass of aqueous solution of urea. 10 2,006 055 235 A1 of DE describes a kind of method of reducing agent quality for identification.Here, the nitrogen or ammonia in exhaust gas are dense Degree is determined by the Abgassensor for being arranged in SCR catalyst downstream.Then, the value measured is compared with fiducial value, and Occur being inferred to the quality decline of reducing agent in the case where deviation.Common NOx sensor shows quick to the intersection of ammonia Perception, i.e. its sensor signal not only include nitrous oxides concentration, but also show the summation signals of nitrogen oxides and ammonia.In nitrogen In the case that oxide sensor is arranged in SCR catalyst downstream, the increase of sensor signal can not only indicate nitrogen oxides Conversion ratio reduces, i.e. instruction nitrous oxides concentration increases, and can indicate that ammonia evolution and ammonia density are increase accordingly.Cause This, can not directly distinguish nitrogen oxides and ammonia using the sensor.
On the one hand, when the reducing agent dosage of stoichiometric excess leads to the ammonia quality stored in SCR catalyst increase, ammonia Relationship between fill level and transformation efficiency of the oxides of nitrogen causes transformation efficiency of the oxides of nitrogen to improve.On the other hand, if SCR is catalyzed Device is most preferably run, then transformation efficiency of the oxides of nitrogen remains unchanged.If the nitrogen oxides measured in this case turns Rate reduces, i.e., the sensor signal increases, then is attributable to the ammonia in SCR catalyst downstream.In such a case, it is possible to recognize It has been exhausted for the maximum storage capacity of SCR catalyst, therefore the ammonia of excessive dispensing without using passes through catalyst converter surface, i.e., Ammonia evolution occurs.
10 2,010 002 620 A1 of DE describes the adjustment by Adaptation factor to dosage quality, the Adaptation factor table Indicating claims the ratio between dosage quality and practical dosage quality.The Adaptation factor is directly changed the presetting quality of reducing agent (Vorsteuermasse), and for will be adjusted to by the nitrous oxides concentration for the sensor measurement for being located at SCR catalyst downstream The nitrogen oxides value of modelling.By I regulator, dosing scheme, which adapts to each system and more longlasting environment, to be influenced, therefore The necessary quantity for adapting to intervene can be reduced in the event of system failure.In addition, the adjusting can also be with respect to non- Often big and burst variation, such as when being filled using the reducing agent of mistake.Here, I regulator highly precisely comes into force, but phase It comes into force with answering also slow, and according to the quality of reducing agent and its dilution, it may be necessary to which several hours identify failure and carry out It adjusts.Here, the dilution of reducing agent is identified by Adaptation factor or by threshold value corresponding with Adaptation factor progress 's.
The another possibility for monitoring reducing agent quality is quality sensor, such as institute in 10 2,014 211 010 A1 of DE It states.The quality sensor is directly arranged in reducing agent tank, and analyzes ammonia density by acoustics and/or optical means.DE 10 2012 209 240 A1 describe it is a kind of for rationalizing the method for quality sensor because the quality sensor have by also Neurological susceptibility caused by the effect of former agent (St ranf lligkeit).
The third possibility of monitoring reducing agent quality is the passive monitoring of SCR catalyst, wherein is passed by nitrogen oxides Sensor detects the nitrous oxides concentration of SCR catalyst upstream and downstream, and thereby determines that efficiency.When in the duration in setting When the efficiency that oversteps the extreme limit, fault identification is carried out.This method is primarily adapted for use in the strong dilution of identification reducing agent, because due to system , particularly NOx sensor tolerance it is relatively large, only can recognize that the very big deviation of efficiency.In order to compensate for this The some big and efficiency change (such as due to being filled with water) that quickly occurs, illustrates one in 10 2,012 221 574 A1 of DE Kind fill level observation device.The quick P adjuster is constantly compensated using the affiliated signal of corresponding NOx sensor The nitrous oxides concentration of the modelling in SCR catalyst downstream.In the case where there is deviation, P adjuster can be in seconds It executes fill level to adjust, until reaching declared efficiency again.
Summary of the invention
Quality control of this method for the reducing agent solution of SCR catalyst, the SCR catalyst include that nitrogen oxides is adjusted Device, the nitrogen oxides adjuster adjust SCR catalyst when this method starts, it are made to meet scheduled transformation efficiency of the oxides of nitrogen, That is, providing the reducing agent of corresponding high quantity to SCR catalyst.It is preferably adjusted to maximum transformation efficiency of the oxides of nitrogen.In next step In, integral fortune not only is carried out by actual ammonia mass flow but also by the ammonia mass flow of modelling especially by I regulator It calculates, obtains the ammonia quality of actual ammonia quality or modelling.
Then, the dosage factor is calculated by asking the quotient of two ammonia quality.Here, being increased also by nitrogen oxides adjuster The dosage quantity of former agent, to compensate the poor quality of reducing agent and realize high transformation efficiency of the oxides of nitrogen.Therefore, reducing agent dosage number The increase of amount leads to the increase of the dosage factor.If the dosage factor of the calculating is more than the first threshold of setting, generated in system Malfunction, the malfunction are attributed to the poor quality of reducing agent solution.Finally, carrying out failed storage in control electronics Device record, the control electronics control the dosage of reducing agent.
Preferably, the ammonia quality that actual ammonia quality and/or modelling are determined only in inquiry is more than scheduled pole The calculating of the dosage factor is just executed when limiting quality.Here, the limiting quanlity depends on the transformation efficiency of the oxides of nitrogen of setting.Thus really The quotient for protecting the ammonia quality of actual ammonia quality and modelling is sufficiently large, so as to identify the increase of the dosage factor, and thus Significant result is provided.
In addition, can then release malfunction again when second threshold of the dosage factor lower than setting.In such case Under, the quality of reducing agent is again good enough to re-executing conventional dosage.
Preferably, when determining actual ammonia quality, by the opening duration of metering valve and frequency meter can be opened Including calculation, which injects reducing agent in the upstream of SCR catalyst.In addition, the ammonia quality of modelling can preferably correspond to The presetting quality calculated.The presetting quality representation is calculated, in order to reach desired nitrogen oxides in SCR catalyst downstream Concentration and the ammonia quality injected.This is by by the nitrous oxides concentration of SCR catalyst upstream and exhaust air mass flow and chemistry The metering factor is multiplied to calculate with the nitrogen oxides efficiency of modelling, and wherein stoichiometric factor indicates nitrogen oxide mass and ammonia Ratio between quality, is thus restored.
The integral operation of the ammonia quality of actual ammonia quality and modelling persistently carries out according to another aspect, but dosage because The calculating of son is discrete progress in time.As a result, the calculating frequency of the dosage factor can depend on until in reality Ammonia quality or modelling ammonia quality integral operation in reach duration until predetermined limit value.The limiting value is preferred Corresponding to limiting quanlity above-mentioned.Dosage quality factor is calculated at this moment discrete filter also can be used.
Preferably, the sensitivity of filter depends on the time interval that reducing agent is added away from the last time.It is particularly preferred It is that the sensitivity of filter is indicated by sensitivity coefficient, and the sensitivity coefficient is included in by filter to dosage matter In the calculating for measuring the factor.Each step that computer program executes this method is set, especially when the computer program is calculating When being executed in equipment or control equipment.This to implement this method in conventional control electronics, without The change in structure is carried out thus.For this purpose, the computer program is stored on machine readable storage medium.
The computer program is run in equipment by controlling in conventional electrical, just obtains electronic control according to the present invention Equipment is arranged for carrying out the quality control of reducing agent solution.
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 shows the chart of transformation efficiency of the oxides of nitrogen according to prior art, which depends on Filling and emptying SCR catalyst and the ammonia fill level when ammonia evolution occurs.
Fig. 2 shows the flow charts of one embodiment of the method according to the invention.
Fig. 3 is shown according to one embodiment of the method according to the invention, actual ammonia quality and mould in SCR catalyst The time plot of the ammonia quality of type.
Fig. 4 is shown according to one embodiment according to the method for the present invention, the time plot of the dosage factor.
Fig. 5 is shown according to another embodiment according to the method for the present invention, the time plot of the dosage factor.
Specific embodiment
In conventional methods where, reducing agent is matched the gas exhaust piping for being given to SCR catalyst upstream by metering valve in dosage module In, on the surface of the SCR catalyst, conversion of nitrogen oxides (is not shown for elemental nitrogen by the ammonia discharged from aqueous solution of urea Out).Indicate that the how many transformation efficiency of the oxides of nitrogen NOxKonvert of conversion of nitrogen oxides depends on the ammonia fill level of SCR catalyst FNH3, and therefore depend on the ammonia quality mNH of dispensing3.It is shown in FIG. 1, according to conventional method embodiment, When 101 SCR catalyst of filling 100 and emptying, about ammonia fill level FNH3This conversion rate of nitrogen NOxKonvert.Ammonia is filled out The flat FNH of water-filling3The record of rated value 102 in the graph and indicate best ammonia filling quality FNH3, under the ammonia filling quality, SCR Catalyst converter is most preferably run in this embodiment.
In addition, being had recorded around rated value 102: relative to the buffer area 103 of nitrogen oxides peak value, the buffer area The excessive nitrogen oxide mass occurred suddenly should be compensated；And the buffer area 104 relative to ammonia evolution 105, it is escaped in ammonia In the case where, ammonia without using passes through catalyst converter surface.Occur when the ammonia escapes 105 in SCR catalyst measured downstream Ammonia quality mNH3Similarly about ammonia fill level FNH3It shows.
Therefore, it for the operation of SCR catalyst, needs accurately to understand ammonia fill level FNH3, thus it is also required to understand logical Cross the ammonia quality mNH of reducing agent solution dispensing3.Due to ammonia quality mNH3Urea quality mCH corresponding to reducing agent4N2O, therefore It depends on the quality Q of reducing agent, and wherein quality Q represents urea quality mCH4N2O and reducing agent gross mass mgesQuotient:
(formula 1).
Fig. 2 shows flow charts according to an embodiment of the method according to the invention.Firstly, by SCR catalyst Adjustment 200 to scheduled high transformation efficiency of the oxides of nitrogen NOxKonvert.Then, start inquiry 201, if there are related system events Barrier 202, all NOx sensors for measurement are ready to measure 203, dosage module activation 204, and match The quantity (such as passing through parallel method) unrestricted 205 for the reducing agent given.If meeting all operating parameters, adjusted by I The actual ammonia mass flow of measurement is carried out integral operation 206 and obtains actual ammonia quality mNH by device3Ist, wherein the reality Ammonia quality pass through the opening time t of metering valveÖffWith opening frequency fÖffEstimation.Meanwhile by the ammonia mass flow of modelling into The ammonia quality mNH that row integral operation 207 is modeled3Mod.The ammonia quality of the modelling corresponds to the presetting quality of ammonia mNH3Vor, the presetting quality of the ammonia are calculated with following formula 2:
(formula 2).
Here,It is the nitrous oxides concentration of SCR catalyst upstream,It is the exhaust mass stream in gas exhaust piping Amount,It is the nitrogen oxides efficiency of the modelling of SCR catalyst, andIt is stoichiometric factor.Stoichiometric factorIndicate ammonia quality mNH3With the ratio of nitrogen oxide mass mNOx.The molal weight of nitrogen dioxideIt is about as much as Effective molal weight of nitrogen oxides present in exhaust gas.In addition, from the unshowned reaction side that the SCR of progress reacts Formula obtains, the amount of substance of ammoniaCorresponding to the amount of substance of nitrogen dioxide, and stoichiometric factorTherefore it is The molal weight of ammoniaWith the molal weight of nitrogen dioxideRatio.Stoichiometric factor as a result,According to public affairs Formula 3 calculates:
(formula 3).
If actual ammonia quality mNH3The ammonia quality mNH of Ist or modelling3Mod is more than 208 settings depending on nitrogen oxidation The limiting quanlity mNH of object conversion ratio NOxKonvert3Grenz then calculates 209 dosage factor facDos according to formula 4, is real The ammonia quality mNH on border3The ammonia quality mNH of Ist and modelling3The quotient of Mod.
(formula 4).
It is explained in Fig. 3 by embodiment.Here it is shown that actual ammonia quality mNH3Ist and modelling Ammonia quality mNH3The time graph of Mod.Here, limiting quanlity mNH3Grenz is selected as 6g.At point 301, actual ammonia quality mNH3Ist is more than scheduled limiting quanlity mNH at about 22.5 minutes time t3Grenz。
In the flowchart of fig. 2, I regulator used in integral operation 206 and 207 is reset in step 210 arranged side by side. It should be noted that the two integral operationes 206 and 207 are to continue to carry out, but the calculating 209 of dosage factor facDos is discrete It carries out.Here, the frequency of the calculating 209 of dosage factor facDos depends on until the quality that oversteps the extreme limit in a step 208 mNH3Duration until Grenz, i.e., above-mentioned 22.5 minutes.In this case, the calculating 209 of dosage factor facDos Pass through EWMA filter 211(Exponential Weighted Moving AVerage exponentially weighted moving average (EWMA)) it carries out, it should EWMA filter is worked based on formula 5.
, wherein as t > 1,(formula 5).
StIndicate the value in the EWMA of time point t, YtIt is the original value of input, and α indicates the sensitivity system of EWMA filter Number, wherein the sensitivity coefficient changes according to the time interval of reducing agent is added away from the last time.In an exemplary embodiment party In formula, this is based on the integrator realization for detecting nitrogen oxide mass mNOx and resetting in the case where supplement is filled out.Only in typing Enough original value YtWhen, the assessment by EWMA filter can be just activated in initialization and/or resetting.
The adjustment variable of dosage factor facDos expression nitrogen oxides adjuster.In order to when the quality Q of reducing agent is poor Reach scheduled high transformation efficiency of the oxides of nitrogen NOxKonvert, nitrogen oxides adjuster must pass through the reducing agent matter of increase dispensing Amount is to increase ammonia filling quality FNH3(referring to Fig. 1).In other words, in order to realize identical transformation efficiency of the oxides of nitrogen NOxKonvert, needs higher reducing agent quality, this leads to the increase of dosage factor facDos.
In next step 212, as shown in figure 4, checking whether dosage factor facDos is more than first threshold 311.This Occur at mark point 312 at about 25 minutes.It in flow chart in Fig. 2, is next set as, generates 213 events in systems Barrier state, the quality Q that this is attributed to reducing agent solution is poor, and therefore creates 214 fault memorizers record.
In an alternative embodiment, the dosage factor facDos of reduction is additionally provided, the improvement of quality Q is corresponded to (such as by replacing reducing agent).In additional step 215, as shown in figure 5, checking whether dosage factor facDos has been lower than the Two threshold values 321.This occurred at mark point 322 at about 70 minutes.Now, as shown in the flowchart of figure 2,216 failures are released State.

Claims (12)

1. the method for the quality control of the reducing agent solution for SCR catalyst, the SCR catalyst is adjusted with nitrogen oxides Device the described method comprises the following steps:
(200) described SCR catalyst is adjusted to scheduled transformation efficiency of the oxides of nitrogen (NOxKonvert)；
Actual ammonia mass flow progress integral operation (206) is obtained into actual ammonia quality (mNH3Ist)；
The ammonia mass flow of modelling is subjected to the ammonia quality (mNH that integral operation (207) are modeled3Mod)；
It calculates (208) dosage factor (facDos), is the actual ammonia quality (mNH3) and the ammonia of the modelling Ist Quality (mNH3Mod quotient)；And
When the dosage factor (facDos) is more than first threshold (311) of (212) setting, (213) malfunction is generated, The quality (Q) that the malfunction is attributed to reducing agent solution is poor.
2. the method according to claim 1, wherein inquired (208), the actual ammonia quality (mNH3) and/or the ammonia quality (mNH of the modelling Ist3It Mod whether is more than) scheduled limiting quanlity (mNH3Grenz), and And only work as the actual ammonia quality (mNH3) and/or the ammonia quality (mNH of the modelling Ist3It Mod) is more than the limit Quality (mNH3The calculating (208) of the dosage factor (facDos) is just executed when Grenz).
3. method according to claim 1 or 2, which is characterized in that when the dosage factor (facDos) sets lower than (215) When fixed second threshold (321), (216) malfunction is released.
4. method according to any of the preceding claims, which is characterized in that in determination (206) the actual ammonia matter Measure (mNH3When Ist), by the opening duration (t of reducing agent metering valveÖff) and opening frequency (fÖff) count.
5. method according to any of the preceding claims, which is characterized in that the ammonia quality of the modelling (mNH3Mod presetting quality (mNH calculated) is corresponded to3Vor), the presetting quality is by by the SCR catalyst upstream Nitrous oxides concentration () and exhaust air mass flow () and stoichiometric factor () and modelling nitrogen oxygen Compound efficiency () be multiplied to calculate.
6. method according to any of the preceding claims, which is characterized in that the actual ammonia quality (mNH3Ist) With the ammonia quality (mNH of the modelling3Mod integral operation (206,207)) persistently carries out, and the dosage factor (facDos) calculating (209) is discrete progress in time.
7. according to the method described in claim 6, it is characterized in that, the frequency of the calculating (209) of the dosage factor (facDos) Rate depends on until in the actual ammonia quality (mNH3) or the ammonia quality (mNH of the modelling Ist3Mod integral operation) It is more than predetermined limit value (mNH in (206,207)3Grenz the duration until).
8. the method according to the description of claim 7 is characterized in that being calculated using (211) discrete filter, (208) are described to match It measures the factor (facDos).
9. according to the method described in claim 8, it is characterized in that, the sensitivity of the filter depends on adding away from the last time The time interval of reducing agent.
10. computer program is arranged for carrying out each step of method according to any one of claim 1 to 9.
11. machine readable storage medium, computer program storage according to claim 10 is on said storage.
12. control electronics are arranged for executing reduction by method according to any one of claim 1 to 9 The quality control of agent solution.
CN201780051768.3A 2016-08-24 2017-06-23 Method for quality control of a reducing agent solution in an SCR catalyst Active CN109642485B (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102016215864.3A DE102016215864A1 (en) 2016-08-24 2016-08-24 Method for quality control of a reducing agent solution in an SCR catalyst
DE102016215864.3 2016-08-24
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