CN108194183B - Method and electronic control unit for detecting SCR ammonia loss during engine shutdown - Google Patents

Method and electronic control unit for detecting SCR ammonia loss during engine shutdown Download PDF

Info

Publication number
CN108194183B
CN108194183B CN201711448102.XA CN201711448102A CN108194183B CN 108194183 B CN108194183 B CN 108194183B CN 201711448102 A CN201711448102 A CN 201711448102A CN 108194183 B CN108194183 B CN 108194183B
Authority
CN
China
Prior art keywords
scr
ammonia
temperature
engine
nitrogen oxides
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201711448102.XA
Other languages
Chinese (zh)
Other versions
CN108194183A (en
Inventor
王龙晓
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Weichai Power Co Ltd
Original Assignee
Weichai Power Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Weichai Power Co Ltd filed Critical Weichai Power Co Ltd
Priority to CN201711448102.XA priority Critical patent/CN108194183B/en
Publication of CN108194183A publication Critical patent/CN108194183A/en
Application granted granted Critical
Publication of CN108194183B publication Critical patent/CN108194183B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • 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
    • 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
    • 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
    • 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

Landscapes

  • 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)

Abstract

The embodiment of the application discloses a method for obtaining SCR ammonia loss in the shutdown process of an engine, which fully considers the factors influencing the ammonia loss adsorbed on an SCR carrier in the shutdown process, wherein the factors not only comprise the shutdown time, but also comprise the treatment of nitrogen oxide remained in an SCR box body after shutdown and the SCR temperature. Based on the multiple factors, the ammonia capacity consumed by treating the nitrogen oxides remained in the SCR box body in the engine shutdown process and the ammonia escape quantity related to the SCR temperature and generated in real time in the shutdown process can be obtained, and the SCR ammonia loss in the engine shutdown process is accurately obtained based on the consumed ammonia capacity and the escape quantity. In addition, the embodiment of the application also discloses an electronic control unit.

Description

Method and electronic control unit for detecting SCR ammonia loss during engine shutdown
Technical Field
The present application relates to engine exhaust gas treatment systems, and more particularly, to a method and electronic control unit for obtaining SCR ammonia loss during engine shutdown.
Background
Selective Catalytic Reduction (SCR) technology is used for nitrogen oxide NO in tail gas emission of diesel vehiclesxThe treatment process of (1) is to spray reducing agent ammonia or urea under the action of catalyst to treat NO in tail gasxReduction to nitrogen gas N2And water H2And O, thereby achieving the purposes of energy conservation and emission reduction. The technology is a mainstream technical route in Europe, and is almost adopted by European long-distance trucks and large buses.
After the engine is shut down, there is a certain amount of ammonia that is adsorbed on the SCR carrier. In order to capture the SCR ammonia loss during engine shutdown, techniques for capturing the SCR ammonia loss during engine shutdown are currently available. One existing method for obtaining SCR ammonia loss during an engine shutdown is to determine the amount of SCR ammonia loss during the shutdown based on the shutdown time. However, the result of the SCR ammonia loss during the engine shutdown process obtained by this method is inaccurate, and affects the calculated value of the SCR physical model, resulting in the discrepancy between the ammonia capacity calculated by the SCR physical model and the ammonia capacity adsorbed in the actual SCR carrier, and further resulting in the increase of the frequency of the triggering of the adaptive and ammonia slip detection functions.
Disclosure of Invention
In view of the above, the present application provides a method and an electronic control unit for acquiring SCR ammonia loss during engine shutdown, so as to accurately acquire SCR ammonia loss during engine shutdown.
In order to solve the technical problem, the following technical scheme is adopted in the application:
a method of deriving SCR ammonia loss during engine shutdown, comprising:
acquiring the average temperature of SCR at the moment of stopping the engine, the ambient temperature and the quality of nitrogen oxides remained in the SCR;
acquiring an SCR temperature attenuation curve according to the SCR average temperature and the ambient temperature;
calculating the ammonia capacity consumed by processing the nitrogen oxides remained in the SCR according to the SCR temperature decay curve and the mass of the nitrogen oxides remained in the SCR; calculating the ammonia escape amount of the engine in the stopping process according to the SCR temperature decay curve and the stopping time;
and adding the consumed ammonia loading capacity and the ammonia escape amount to obtain the sum which is the SCR ammonia loss in the engine stop process.
Optionally, the obtaining an SCR temperature decay curve according to the SCR average temperature and the ambient temperature specifically includes:
and searching a MAP graph according to the SCR average temperature and the ambient temperature to obtain a temperature attenuation curve of the SCR temperature, wherein the MAP graph is obtained by calibrating in advance according to different SCR temperatures and ambient temperatures.
Optionally, the obtaining an SCR temperature decay curve according to the SCR average temperature and the ambient temperature specifically includes:
and acquiring an SCR temperature attenuation curve according to a pre-constructed SCR temperature model.
Optionally, obtaining the mass of nitrogen oxides remaining in the SCR specifically includes:
acquiring the mass flow of the tail gas at the moment when the engine stops, the concentration of nitric oxide in the tail gas and the volume of the SCR box body;
and estimating the mass of the nitrogen oxide remained in the SCR according to the mass flow of the tail gas, the concentration of the nitrogen oxide in the tail gas and the volume of the SCR box body.
Optionally, after adding the consumed ammonia load and the ammonia slip amount to obtain a sum, which is the SCR ammonia loss during the engine shutdown process, the method further includes:
and when the engine is restarted after being stopped, correcting the current ammonia capacity of the SCR according to the SCR ammonia loss in the engine stopping process.
An electronic control unit comprising:
the system comprises a first acquisition module, a second acquisition module and a control module, wherein the first acquisition module is used for acquiring the average temperature of the SCR at the stop moment of an engine, the ambient temperature and the quality of nitrogen oxides remained in the SCR;
the second acquisition module is used for acquiring an SCR temperature attenuation curve according to the SCR average temperature and the ambient temperature;
the first calculation module is used for calculating the ammonia capacity consumed by processing the nitrogen oxides remained in the SCR according to the SCR temperature decay curve and the mass of the nitrogen oxides remained in the SCR;
the second calculation module is used for calculating the ammonia escape amount of the engine in the stopping process according to the SCR temperature decay curve and the stopping time;
and the adding module is used for adding the consumed ammonia loading capacity and the ammonia escape amount to obtain the sum which is the SCR ammonia loss in the engine stop process.
Optionally, the second obtaining module is specifically configured to:
and searching a MAP graph according to the SCR average temperature and the ambient temperature to obtain a temperature attenuation curve of the SCR temperature, wherein the MAP graph is obtained by calibrating in advance according to different SCR temperatures and ambient temperatures.
Optionally, the second obtaining module is specifically configured to:
and acquiring an SCR temperature attenuation curve according to a pre-constructed SCR temperature model.
Optionally, the first computing module specifically includes:
the acquisition submodule is used for acquiring the mass flow of the tail gas at the stop moment of the engine, the concentration of nitrogen oxides in the tail gas and the volume of the SCR box body;
and the estimation submodule is used for estimating the mass of the nitrogen oxides remained in the SCR according to the mass flow of the exhaust, the concentration of the nitrogen oxides in the exhaust and the volume of the SCR box.
Optionally, the electronic control unit further comprises:
and the correction module is used for correcting the current ammonia capacity of the SCR according to the SCR ammonia loss in the engine stop process when the engine is started again after the engine is stopped.
Compared with the prior art, the method has the following beneficial effects:
after the engine is shut down, certain nitrogen oxide still remains in the SCR box body, and the temperature of the SCR catalyst is higher at the moment, and the residual nitrogen oxide can react with ammonia adsorbed on the SCR carrier, so that the loss of the ammonia capacity of the SCR is caused. Meanwhile, after the engine is stopped, a part of ammonia adsorbed on the SCR carrier can escape in real time, so that the ammonia capacity of the SCR is lost. And the ammonia escape amount is related to the SCR temperature, the higher the SCR temperature is, the larger the ammonia escape amount is, and the lower the SCR temperature is, the smaller the ammonia escape amount is. As such, SCR ammonia loss during engine shutdown consists of two parts: the ammonia load consumed to treat residual nitrogen oxides and the amount of ammonia slip associated with SCR temperature that occurs in real time during shutdown.
Based on this, the method for acquiring the ammonia loss of the SCR in the engine shutdown process provided by the embodiment of the present application fully considers the factors influencing the ammonia loss adsorbed on the SCR carrier in the shutdown process, and the factors include not only the shutdown time, but also the nitrogen oxide remaining in the SCR tank after the shutdown and the SCR temperature. Based on the multiple factors, the ammonia capacity consumed by treating the nitrogen oxides remained in the SCR box body in the engine stopping process and the ammonia escape quantity related to the SCR temperature can be accurately obtained, and the SCR ammonia loss in the engine stopping process can be accurately obtained based on the consumed ammonia capacity and the escape quantity.
Drawings
In order that the manner in which the embodiments of the present application are attained and can be understood in detail, a brief description of the drawings will now be provided. It is to be understood that these drawings are merely illustrative of some of the embodiments of the application.
FIG. 1 is a schematic flow chart of a method for obtaining SCR ammonia loss during engine shutdown provided by an embodiment of the present application;
FIG. 2 is a schematic view of an SCR temperature decay curve provided by an embodiment of the present application;
FIG. 3 is a schematic diagram of a MAP provided by an embodiment of the present application;
fig. 4 is a schematic structural diagram of an electronic control unit provided in an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and technical effects of the present invention clearer and more complete, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.
Before describing the embodiments of the present application, the SCR system will be described first.
SCR aims at nitrogen oxide NO in tail gas emission of diesel vehiclexThe treatment process of (1) is to spray reducing agent ammonia or urea under the action of catalyst to treat NO in tail gasxReduction to nitrogen gas N2And water H2And O, thereby achieving the purposes of energy conservation and emission reduction. The technology is a mainstream technical route in Europe, and is almost adopted by European long-distance trucks and large buses.
The basic operating principle of the SCR system is as follows: the tail gas from the turbine enters an exhaust mixing pipe, a urea metering injection device is arranged on the mixing pipe, urea aqueous solution is injected, and NH is generated after hydrolysis and pyrolysis reaction of urea at high temperature3Using NH on the surface of the SCR system catalyst3Reduction of NOXDischarge N2. Typically, a loss of 100L of fuel will be accompanied by a loss of 5L of liquid urea in water.
The main chemical reactions that occur in SCR are as follows:
urea hydrolysis:
(NH2)2CO+H2O→2NH3+CO2
NOXreduction:
NO+NO2+2NH3→2N2+3H2O
NH3and (3) oxidation:
4NH3+3O2→2N2+6H2O
the complex physical and chemical reactions that occur in SCR systems include: injection, atomization, evaporation of aqueous urea solution, hydrolysis of urea and pyrolysis gas phase chemical reaction, and NOXOn the surface of the catalyst with NH3The catalytic surface chemistry that takes place.
As described above, in the SCR system, ammonia is used as a reaction gas for treating nitrogen oxides, and the SCR ammonia content has a great influence on the exhaust gas treatment effect. The SCR ammonia loading capacity is adapted to the actual working condition of the engine, so that an ideal tail gas treatment effect can be achieved. If the SCR ammonia loading is too low, it may result in the nitrogen oxides in the exhaust emissions not being completely treated, and if the SCR ammonia loading is too high, it may result in too much ammonia escaping from the SCR media, resulting in ammonia slip. Therefore, in order to achieve good exhaust gas treatment effect, an Electronic Control Unit (ECU) needs to know the actual ammonia load of the SCR in real time.
However, after the engine is shut down, because a certain amount of nitrogen oxides still remain in the SCR tank, and the temperature of the SCR catalyst is high at this time, the remaining nitrogen oxides may react with ammonia adsorbed on the SCR carrier, resulting in a loss of the SCR ammonia capacity. Meanwhile, after the engine is stopped, a part of ammonia adsorbed on the SCR carrier can escape in real time, so that the ammonia capacity of the SCR is lost. And the ammonia escape amount is related to the SCR temperature, the higher the SCR temperature is, the larger the ammonia escape amount is, and the lower the SCR temperature is, the smaller the ammonia escape amount is. As such, the engine shutdown process may result in a loss of SCR ammonia capacity. When the engine is restarted after being stopped, in order to enable the ECU to accurately know the actual ammonia capacity of the SCR, the current ammonia capacity of the SCR needs to be corrected by using the ammonia loss generated in the process of stopping the engine.
In order to correct the current SCR ammonia loading amount of the engine that is restarted after the engine is stopped, the SCR ammonia loss in the engine stopping process needs to be accurately obtained.
Based on this, the embodiment of the application fully considers the factors influencing the loss of ammonia adsorbed on the SCR carrier in the shutdown process, and the factors not only comprise the shutdown time, but also comprise the nitrogen oxides remained in the SCR box body after the shutdown and the SCR temperature. Based on the factors, the ammonia capacity consumed due to the treatment of the nitrogen oxides remained in the SCR box body in the engine stopping process and the ammonia escape amount related to the SCR temperature can be obtained, and the SCR ammonia loss in the engine stopping process can be accurately obtained based on the consumed ammonia capacity and the escape amount.
Referring to fig. 1, a method for acquiring SCR ammonia loss during engine shutdown provided by an embodiment of the present application includes the following steps:
s101: the average temperature of the SCR, the ambient temperature and the mass of nitrogen oxides remaining in the SCR catalyst at the time of engine shutdown are obtained.
As a specific example of the present application, a thermometer may be mounted on the SCR catalyst in advance, and the ECU may acquire the average temperature of the SCR at the time of engine stop by monitoring with the thermometer.
In the embodiment of the application, the ambient temperature is the external ambient temperature of the SCR catalyst at the time of engine shutdown.
As a specific example of the present application, the ECU may directly acquire the mass of nitrogen oxides remaining in the SCR catalyst. As another specific example of the present application, the mass of nitrogen oxides remaining in the SCR catalyst can be estimated from the exhaust gas mass flow at the time of engine shutdown, the concentration of nitrogen oxides in the exhaust gas, and the volume of the SCR tank. In this way, in order to estimate the mass of the nitrogen oxides remaining in the SCR catalyst,
the ECU acquires the mass flow of the tail gas at the moment when the engine is stopped, the concentration of nitrogen oxides in the tail gas and the volume of the SCR box body; and then estimating the mass of the nitrogen oxide remained in the SCR according to the mass flow of the tail gas, the concentration of the nitrogen oxide in the tail gas and the volume of the SCR box body.
Specifically, the mass of nitrogen oxides remaining within the SCR may be equal to the product of the exhaust gas mass flow, the concentration of nitrogen oxides in the exhaust gas, and the volume of the SCR tank.
S102: and acquiring an SCR temperature attenuation curve according to the average SCR temperature and the ambient temperature.
It should be noted that the SCR temperature decay curve is used to show the variation trend of the SCR temperature with time. As an example, the SCR temperature decay curve may be as shown in FIG. 2.
Therefore, the SCR temperature decay curve is not only related to the initial temperature of the SCR, but also related to the outside temperature, and the lower the outside temperature, the faster the SCR temperature decay, and the higher the outside temperature, the slower the SCR temperature decay. Therefore, in the embodiment of the present application, it is necessary to obtain the SCR temperature decay curve according to the average SCR temperature at the time of engine shutdown and the ambient temperature.
As a specific embodiment of the application, according to experience, a plurality of SCR average temperatures which often occur and SCR temperature change trends of a plurality of environment temperatures which an engine is often in can be calibrated in advance to obtain a MAP chart of SCR temperature change along with time. As an example, the MAP graph may be as shown in FIG. 3. In FIG. 3, the average temperatures of 4 SCRs are shown (
Figure GDA0002211426980000061
And
Figure GDA0002211426980000062
) And 4 ambient temperatures: (And
Figure GDA0002211426980000072
) The variation trend of the SCR temperature along with the time, namely the SCR temperature decay curve S1To S4。
In this embodiment, a MAP table calibrated in advance may be searched according to the average SCR temperature and the ambient temperature, and an SCR temperature decay curve corresponding to the average SCR temperature and the ambient temperature may be searched from the MAP table. For example, assume that the average SCR temperature is obtainedAt an ambient temperature of
Figure GDA0002211426980000074
The SCR temperature decay curve obtained according to the SCR average temperature and the ambient temperature is a curve S1.
As another specific example of the present application, an SCR temperature model may also be constructed in advance, and parameters in the SCR temperature model include: average SCR temperature at engine stop and ambient temperature. Thus, the SCR temperature decay curve can be obtained according to the pre-constructed SCR temperature model. The constructed SCR temperature model can be regarded as a mathematical formula, so that no matter what the obtained SCR average temperature and the obtained value of the environment temperature are, the corresponding SCR temperature attenuation curve can be obtained through the constructed SCR temperature model.
S103: calculating the ammonia capacity consumed by processing the nitrogen oxides remained in the SCR according to the SCR temperature decay curve and the mass of the nitrogen oxides remained in the SCR; and calculating the ammonia escape amount of the engine in the stopping process according to the SCR temperature decay curve and the stopping time.
Since the chemical reaction in the SCR is related to the temperature in the SCR, it is necessary to calculate the amount of ammonia consumed to process the nitrogen oxides remaining in the SCR from the actual temperature of the SCR and the mass of the nitrogen oxides remaining in the SCR as shown in the SCR temperature decay curve.
In addition, after the engine is stopped, a part of ammonia adsorbed on the SCR carrier can escape in real time, so that the ammonia capacity of the SCR is lost. And the ammonia escape amount is related to the SCR temperature, the higher the SCR temperature is, the larger the ammonia escape amount is, and the lower the SCR temperature is, the smaller the ammonia escape amount is. Therefore, in order to accurately acquire the SCR ammonia consumption in the engine stopping process, the ammonia slip amount in the engine stopping process needs to be calculated according to the SCR temperature decay curve and the stopping time.
In the embodiment of the present invention, when the engine is stopped, the ECU records the stop time, and when the engine is restarted after the engine is stopped, records the restart time, and determines the stop time of the engine based on the time difference between the two times.
S104: and adding the consumed ammonia loading capacity and the ammonia escape amount to obtain the sum which is the SCR ammonia loss in the engine stop process.
The above is a specific implementation manner of the method for acquiring the SCR ammonia loss during the engine shutdown process provided by the embodiment of the present application. In this particular implementation, factors that affect the loss of ammonia adsorbed on the SCR carrier during shutdown are fully considered, including not only the time of shutdown, but also the treatment of nitrogen oxides remaining in the SCR tank after shutdown and the SCR temperature. Based on the multiple factors, the ammonia capacity consumed by treating the nitrogen oxides remained in the SCR box body in the shutdown process of the engine and the ammonia escape quantity related to the SCR temperature and generated in real time in the shutdown process can be obtained, and the SCR ammonia loss in the shutdown process of the engine can be accurately obtained based on the consumed ammonia capacity and the escape quantity.
Further, based on the accurate SCR ammonia loss, the ammonia load calculated by the SCR physical model can be made to coincide with the actual ammonia load adsorbed in the SCR carrier, and thus the frequency of adaptation and ammonia slip detection function triggers can be reduced.
In addition, in order to make the ECU accurately obtain the actual ammonia load in the SCR, as another specific implementation manner of the present application, after S104, the following steps may be further included:
and when the engine is restarted after being stopped, correcting the current ammonia capacity of the SCR according to the SCR ammonia loss in the engine stopping process.
When the engine is restarted after being stopped, the ECU is also started at the same time, and at this time, the ammonia amount in the SCR detected by the ECU is the SCR ammonia amount corresponding to the last engine stop. However, since there is a loss in the ammonia capacity in the SCR during engine shutdown, it is necessary to correct the current ammonia capacity of the SCR according to the SCR ammonia loss during engine shutdown in order for the ECU to accurately obtain the actual ammonia capacity in the SCR at restart after engine shutdown. The corrected SCR ammonia load is the SCR ammonia load at the last engine shutdown minus the ammonia loss incurred during the engine shutdown.
Because the ammonia loss in the engine shutdown process can be accurately acquired in the embodiment of the application, the current ammonia capacity of the SCR can be accurately corrected based on the accurate ammonia loss, so that the ECU can accurately acquire the actual ammonia capacity of the SCR.
The above is a specific implementation manner of the method for acquiring the SCR ammonia loss in the engine shutdown process provided by the embodiment of the present application. Based on the specific implementation mode, the embodiment of the application also provides an electronic control unit.
Referring to fig. 4, an electronic control unit provided in an embodiment of the present application includes:
a first obtaining module 41, configured to obtain an average temperature of the SCR at the time when the engine is stopped, an ambient temperature, and a mass of nitrogen oxides remaining in the SCR;
a second obtaining module 42, configured to obtain an SCR temperature decay curve according to the SCR average temperature and the ambient temperature;
a first calculation module 43, configured to calculate an ammonia capacity consumed for processing the nitrogen oxides remaining in the SCR according to the SCR temperature decay curve and the mass of the nitrogen oxides remaining in the SCR;
the second calculation module 44 is used for calculating the ammonia slip amount in the stopping process of the engine according to the SCR temperature decay curve and the stopping time;
and the adding module 45 is used for adding the consumed ammonia loading amount and the ammonia escape amount, and the obtained sum is the SCR ammonia loss in the engine stop process.
As an optional embodiment of the present application, in order to enable the ECU to accurately obtain the actual ammonia capacity of the SCR when the engine is restarted after being stopped, the electronic control unit may further include:
and a correction module 46 for correcting the current ammonia capacity of the SCR based on the SCR ammonia loss during the engine shutdown when the engine is restarted after shutdown.
As a specific example of the present application, in order to more accurately acquire the SCR temperature trend with time, the second acquiring module 42 may specifically be configured to: and searching a MAP chart according to the average SCR temperature and the ambient temperature to obtain a temperature attenuation curve of the SCR temperature, wherein the MAP chart is obtained by calibrating in advance according to different SCR temperatures and ambient temperatures.
As another specific example of the present application, in order to ensure that the SCR temperature trend over time can be obtained, the second obtaining module 42 may also be specifically configured to obtain an SCR temperature decay curve according to a pre-constructed SCR temperature model.
As another specific example of the present application, in order to accurately acquire the mass of the nitrogen oxides remaining in the SCR, the first calculation module 43 may specifically include:
the acquisition submodule is used for acquiring the mass flow of the tail gas at the stop moment of the engine, the concentration of nitrogen oxides in the tail gas and the volume of the SCR box body;
and the estimation submodule is used for estimating the mass of the nitrogen oxides remained in the SCR according to the mass flow of the exhaust, the concentration of the nitrogen oxides in the exhaust and the volume of the SCR box.
The above are merely examples of the present application and are not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims (10)

1. A method of capturing SCR ammonia loss during engine shutdown, comprising:
acquiring the average temperature of SCR at the moment of stopping the engine, the ambient temperature and the quality of nitrogen oxides remained in the SCR;
acquiring an SCR temperature attenuation curve according to the SCR average temperature and the ambient temperature;
calculating the ammonia capacity consumed by processing the nitrogen oxides remained in the SCR according to the SCR temperature decay curve and the mass of the nitrogen oxides remained in the SCR; calculating the ammonia escape amount of the engine in the stopping process according to the SCR temperature decay curve and the stopping time;
and adding the consumed ammonia loading capacity and the ammonia escape amount to obtain the sum which is the SCR ammonia loss in the engine stop process.
2. The method according to claim 1, wherein the obtaining an SCR temperature decay curve according to the SCR average temperature and the ambient temperature specifically comprises:
and searching a MAP graph according to the SCR average temperature and the ambient temperature to obtain a temperature attenuation curve of the SCR temperature, wherein the MAP graph is obtained by calibrating in advance according to different SCR temperatures and ambient temperatures.
3. The method according to claim 1, wherein the obtaining an SCR temperature decay curve according to the SCR average temperature and the ambient temperature specifically comprises:
and acquiring an SCR temperature attenuation curve according to a pre-constructed SCR temperature model.
4. The method according to claim 1, wherein obtaining the mass of nitrogen oxides remaining in the SCR comprises:
acquiring the mass flow of the tail gas at the moment when the engine stops, the concentration of nitric oxide in the tail gas and the volume of the SCR box body;
and estimating the mass of the nitrogen oxide remained in the SCR according to the mass flow of the tail gas, the concentration of the nitrogen oxide in the tail gas and the volume of the SCR box body.
5. The method of claim 1, wherein said adding said consumed ammonia load to an ammonia slip amount, the resulting sum being the SCR ammonia loss during engine shutdown, further comprises:
and when the engine is restarted after being stopped, correcting the current ammonia capacity of the SCR according to the SCR ammonia loss in the engine stopping process.
6. An electronic control unit, comprising:
the system comprises a first acquisition module, a second acquisition module and a control module, wherein the first acquisition module is used for acquiring the average temperature of the SCR at the stop moment of an engine, the ambient temperature and the quality of nitrogen oxides remained in the SCR;
the second acquisition module is used for acquiring an SCR temperature attenuation curve according to the SCR average temperature and the ambient temperature;
the first calculation module is used for calculating the ammonia capacity consumed by processing the nitrogen oxides remained in the SCR according to the SCR temperature decay curve and the mass of the nitrogen oxides remained in the SCR;
the second calculation module is used for calculating the ammonia escape amount of the engine in the stopping process according to the SCR temperature decay curve and the stopping time;
and the adding module is used for adding the consumed ammonia loading capacity and the ammonia escape amount to obtain the sum which is the SCR ammonia loss in the engine stop process.
7. The electronic control unit of claim 6, wherein the second obtaining module is specifically configured to:
and searching a MAP graph according to the SCR average temperature and the ambient temperature to obtain a temperature attenuation curve of the SCR temperature, wherein the MAP graph is obtained by calibrating in advance according to different SCR temperatures and ambient temperatures.
8. The electronic control unit of claim 6, wherein the second obtaining module is specifically configured to:
and acquiring an SCR temperature attenuation curve according to a pre-constructed SCR temperature model.
9. The electronic control unit of claim 6, wherein the first computing module specifically comprises:
the acquisition submodule is used for acquiring the mass flow of the tail gas at the stop moment of the engine, the concentration of nitrogen oxides in the tail gas and the volume of the SCR box body;
and the estimation submodule is used for estimating the mass of the nitrogen oxides remained in the SCR according to the mass flow of the exhaust, the concentration of the nitrogen oxides in the exhaust and the volume of the SCR box.
10. The electronic control unit of claim 6, further comprising:
and the correction module is used for correcting the current ammonia capacity of the SCR according to the SCR ammonia loss in the engine stop process when the engine is started again after the engine is stopped.
CN201711448102.XA 2017-12-27 2017-12-27 Method and electronic control unit for detecting SCR ammonia loss during engine shutdown Active CN108194183B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201711448102.XA CN108194183B (en) 2017-12-27 2017-12-27 Method and electronic control unit for detecting SCR ammonia loss during engine shutdown

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201711448102.XA CN108194183B (en) 2017-12-27 2017-12-27 Method and electronic control unit for detecting SCR ammonia loss during engine shutdown

Publications (2)

Publication Number Publication Date
CN108194183A CN108194183A (en) 2018-06-22
CN108194183B true CN108194183B (en) 2020-01-03

Family

ID=62584734

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201711448102.XA Active CN108194183B (en) 2017-12-27 2017-12-27 Method and electronic control unit for detecting SCR ammonia loss during engine shutdown

Country Status (1)

Country Link
CN (1) CN108194183B (en)

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7726118B2 (en) * 2006-09-18 2010-06-01 Ford Global Technologies, Llc Engine-off ammonia vapor management system and method
JP4375483B2 (en) * 2008-02-22 2009-12-02 トヨタ自動車株式会社 Exhaust gas purification device for internal combustion engine
US8671666B2 (en) * 2010-03-11 2014-03-18 Cummins Inc. System and apparatus for enhancing exhaust aftertreatment startup emissions control
DE102011085108A1 (en) * 2011-10-24 2013-04-25 Ford Global Technologies, Llc Method for controlling an injection device for feeding an ammonia-releasing reducing agent into an exhaust gas purification system of an internal combustion engine
US8862370B2 (en) * 2012-08-02 2014-10-14 Ford Global Technologies, Llc NOx control during engine idle-stop operations
EP2754871B1 (en) * 2013-01-15 2017-11-15 Ford Global Technologies, LLC Method for controlling the operation of an exhaust aftertreatment system in a vehicle
US9217350B2 (en) * 2013-11-13 2015-12-22 Ford Global Technologies, Llc Method and system for reductant injector degradation
CN104314650A (en) * 2014-07-29 2015-01-28 潍柴动力股份有限公司 SCR (selective catalytic reduction) feed-forward control method and device

Also Published As

Publication number Publication date
CN108194183A (en) 2018-06-22

Similar Documents

Publication Publication Date Title
EP3660288B1 (en) Injection amount control method and device for scr urea injection system in engine
US9115630B1 (en) Diagnostic for a mid-catalyst NH3 sensor
DE102009038948B4 (en) System and method for controlling lean nitrogen oxide emission
US8881508B2 (en) SCR control system utilizing a differential NH3 and NOx measurement using an exhaust gas sensor coupled with a micro SCR catalyst
CN102027212B (en) Method for correcting nitrogen oxide emission models
CN101832167B (en) Ammonia adsorption control method in SCR (Selective catalytic reduction) catalyst
US9181845B2 (en) Method for calculating the NO2 content at the inlet of a selective reduction catalyst and device for the implementation of this method
US11047283B2 (en) Method of monitoring an SCR catalytic converter
CN113006913B (en) Urea crystallization risk early warning method and device, computer equipment and storage medium
CN110230530B (en) Method, device and system for heating engine SCR system pipeline
US9482133B2 (en) Exhaust emission control system of internal combustion engine
US9739190B2 (en) Method and apparatus to control reductant injection into an exhaust gas feedstream
US9145816B2 (en) Exhaust treatment methods and systems
CN111226027B (en) Method for operating a diesel engine and diesel engine with NH3 concentration detection
JP2018178850A (en) Control device for exhaust emission control system
CN113202605B (en) Method for calculating ammonia leakage amount of SCR (Selective catalytic reduction) aftertreatment system
CN108194183B (en) Method and electronic control unit for detecting SCR ammonia loss during engine shutdown
US8808630B2 (en) Exhaust gas catalytic converter system and method for operating an exhaust gas catalytic converter
KR102540930B1 (en) Selective catalytic reduction (scr) catalyst apparatus for a vehicle and method for controlling thereof
JP2012057591A (en) Exhaust emission control device
CN107044323A (en) A kind of SCR catalyst ammonia amount of storage computational methods and the device used
CN113348298A (en) Method for injecting ammonia in gaseous form into the exhaust line of a heat engine
EP4187066A1 (en) A method and system for sensor analysis in an exhaust gas aftertreatment system
CN113404577A (en) Method and device for identifying fuel oil filling point based on Internet of vehicles technology
US8940260B2 (en) Supplemental ammonia storage and delivery system

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant