CN111798936B - Method for calculating NH3 storage amount of SCR (Selective catalytic reduction) catalyst - Google Patents

Method for calculating NH3 storage amount of SCR (Selective catalytic reduction) catalyst Download PDF

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CN111798936B
CN111798936B CN202010534302.2A CN202010534302A CN111798936B CN 111798936 B CN111798936 B CN 111798936B CN 202010534302 A CN202010534302 A CN 202010534302A CN 111798936 B CN111798936 B CN 111798936B
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CN111798936A (en
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白桃李
程欢
李林
张衡
周杰敏
陈玉俊
韩虎
王梅俊
李芳�
郑攀
杨晓莹
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Dongfeng Commercial Vehicle Co Ltd
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Abstract

The application relates to a method for calculating the amount of NH3 stored in an SCR (selective catalytic reduction) catalyst, which relates to the technical field of engines and comprises the following steps: calculating to obtain a final NH3 storage capacity value according to the basic NH3 storage capacity value and the NH3 storage capacity correction coefficient; calculating to obtain an initial value of stored NH3 amount according to the initial value of stored NH3, the correction coefficient of the initial value of stored NH3 and the compensation amount of the initial value of stored NH 3; calculating the real-time NH3 storage rate according to the effective NH3 injection mass flow, the NH3 mass flow consumed by the NOx conversion, the carrier temperature, the exhaust mass flow, the carrier aging coefficient and the current NH3 storage variable quantity; and calculating to obtain the real-time stored NH3 according to the initial value of the stored NH3 amount and the real-time stored NH3 rate. The application considers the oxidation amount of NH3 gas and the NH3 storage capacity of the SCR catalyst under the current working condition, reduces the influence of interference factors on the calculation result to a certain extent, and improves the calculation accuracy.

Description

Method for calculating NH3 storage amount of SCR (Selective catalytic reduction) catalyst
Technical Field
The invention relates to the technical field of engines, in particular to a method for calculating the amount of NH3 stored in an SCR (selective catalytic reduction) catalyst.
Background
When the amount of stored NH3 of an SCR (Selective Catalytic Reduction) catalyst is calculated, the amount is obtained mainly according to the NH3 gas injection amount and the NH3 gas reaction amount integral, and the initial amount of stored NH3 of the SCR catalyst is read by a controller memory after the ECU is electrified again.
However, as NH3 can be adsorbed or desorbed on the surface of the catalyst, interference information is added to the calculation process of the amount of stored NH3 of the SCR catalyst;
if the real-time stored NH3 amount is not accurately obtained, uncertainty may be introduced into urea injection control, and Nox conversion efficiency may be insufficient or NH3 slip may occur during transient conditions. At the same time, if the calculated amount of stored NH3 is not accurate, the availability of catalyst conversion performance may be reduced
Therefore, in order to eliminate the interference factors and ensure the conversion performance of the catalyst, a new calculation scheme of the amount of the stored NH3 of the SCR catalyst is urgently needed.
Disclosure of Invention
The embodiment of the application provides a method for calculating the amount of NH3 stored in an SCR (selective catalytic reduction) catalyst, which considers the oxidation amount of NH3 gas and the NH3 storage capacity of the SCR catalyst under the current working condition, reduces the influence of interference factors on the calculation result to a certain extent, improves the calculation accuracy and guarantees the availability of the conversion performance of the catalyst at the later stage.
In a first aspect, a method for calculating an amount of stored NH3 for an SCR catalyst is provided, the method comprising the steps of:
calculating and obtaining a final NH3 storage capacity value of the SCR catalyst according to a basic NH3 storage capacity value and a NH3 storage capacity correction coefficient of the SCR catalyst;
when the ECU is electrified again, calculating and obtaining an initial value of the stored NH3 amount of the SCR catalyst according to the initial value of the stored NH3 of the SCR catalyst, the correction coefficient of the initial value of the stored NH3 and the compensation amount of the initial value of the stored NH 3;
calculating the real-time NH3 storage rate of the SCR catalyst according to the effective NH3 injection mass flow corresponding to the SCR catalyst, the NH3 mass flow consumed by NOx conversion, the carrier temperature, the exhaust mass flow, the carrier aging coefficient and the current NH3 storage variable quantity;
calculating and obtaining real-time stored NH3 amount corresponding to the SCR catalyst according to the initial value of the stored NH3 amount and the real-time stored NH3 rate; wherein the content of the first and second substances,
the method for calculating the real-time NH3 storage rate of the SCR catalyst according to the effective NH3 injection mass flow corresponding to the SCR catalyst, the NH3 mass flow consumed by NOx conversion, the carrier temperature, the exhaust mass flow, the carrier aging coefficient and the current NH3 storage variable quantity comprises the following steps:
judging whether a first difference value between the effective NH3 injection mass flow and the NH3 mass flow consumed by the NOx conversion is smaller than a preset first threshold value or not;
when the first difference value is smaller than a preset first threshold value, the residual coefficient after NH3 gas phase oxidation is 1;
calculating and obtaining a stored NH3 rate after considering NH3 gas phase oxidation according to the effective NH3 injection mass flow, the NH3 mass flow consumed by the conversion Nox and the residual coefficient after NH3 gas phase oxidation;
judging a numerical value of a preset calibration switching value;
when the value of the calibrated switching value is equal to 0, the real-time stored NH3 rate is equal to the stored NH3 rate after considering NH3 gas phase oxidation;
when the value of the calibrated switching value is equal to 1, the real-time stored NH3 rate is equal to the difference between the stored NH3 rate after considering NH3 gas phase oxidation and the release oxidation rate of the adsorbed NH 3.
Specifically, the final NH3 capacity value calculation formula corresponding to the final NH3 capacity value is as follows:
MNH3cap＝Mbase_NH3cap×fNH3cap(ii) a Wherein the content of the first and second substances,
MNH3capfor the final NH3 storage capacity value, Mbase_NH3capOn the basis of the NH3 capacity value, fNH3capThe correction coefficient is NH3 storage capacity.
Specifically, the calculation formula of the initial value of the stored NH3 amount corresponding to the initial value of the stored NH3 amount is as follows:
MNH3int＝Mint_EEPROM×fint+Mint_offset(ii) a Wherein the content of the first and second substances,
MNH3intis the initial value of the amount of stored NH3, Mint_EEPROMIs the initial value of NH3 storage, fintCorrecting the coefficient for the initial value of stored NH3, Mint_offsetAnd compensating the initial value of the stored NH 3.
Further, the method comprises the following steps:
and when the first difference value is not less than a preset first threshold value, calculating to obtain the residual coefficient after the NH3 gas phase oxidation according to the NH3 gas phase oxidation coefficient corresponding to the aged catalyst, the NH3 gas phase oxidation coefficient corresponding to the new catalyst and the interpolation coefficient of the NH3 gas phase oxidation coefficient.
Further, the method comprises the following steps:
and calculating to obtain the release oxidation rate of the adsorbed NH3 according to the release oxidation coefficient of the adsorbed NH3 corresponding to the aged SCR catalyst, the release oxidation coefficient of the adsorbed NH3 corresponding to the new catalyst, the interpolation coefficient of the release oxidation coefficient of the adsorbed NH3 and the exhaust mass flow.
Specifically, the calculation formula considering the stored NH3 rate after the gas-phase oxidation of NH3 is:
Figure GDA0002974795580000031
Figure GDA0002974795580000032
is the effective NH3 injection mass flow,
Figure GDA0002974795580000033
NH3 Mass flow, f consumed for the conversion of NoxNH3o2gasFor the residual coefficient after vapor phase oxidation of NH3,
Figure GDA0002974795580000034
the stored NH3 rate after gas phase oxidation of NH3 is considered.
Specifically, according to the NH3 gas phase oxidation coefficient corresponding to the aged catalyst, the NH3 gas phase oxidation coefficient corresponding to the new catalyst, and the interpolation coefficient of the NH3 gas phase oxidation coefficient, the calculation formula for calculating the residual coefficient after NH3 gas phase oxidation is as follows:
fNH3o2gas＝1-[fOld_NH3o2gas+(fNew_NH3o2gas-fOld_NH3o2gas)×fmap_NH3o2gas]；
fOld_NH3o2gasthe corresponding NH3 gas phase oxidation coefficient f of the aging catalystNew_NH3o2gasThe corresponding NH3 gas phase oxidation coefficient f of the new catalystmap_NH3o2gasIs an interpolation factor of the NH3 vapor phase oxidation factor, fNH3o2gasIs the residual coefficient after the gas phase oxidation of the NH 3.
Specifically, the formula for obtaining the release oxidation rate of the adsorbed NH3 by calculation according to the release oxidation coefficient of the adsorbed NH3 corresponding to the aged SCR catalyst, the release oxidation coefficient of the adsorbed NH3 corresponding to the new catalyst, the interpolation coefficient of the release oxidation coefficient of the adsorbed NH3, and the exhaust mass flow is as follows:
Figure GDA0002974795580000041
wherein the content of the first and second substances,
fOld_NH3o2adsreleasing an oxidation coefficient, f, for the adsorbed NH3 corresponding to the aged SCR catalystNew_NH3o2adsReleasing the oxidation coefficient, f, for the adsorbed NH3 corresponding to the new catalystmap_NH3o2adsAn interpolation coefficient for the adsorbed NH3 release oxidation coefficient,
Figure GDA0002974795580000042
for the purpose of the exhaust gas mass flow,
Figure GDA0002974795580000043
releasing the oxidation rate for the adsorbed NH 3.
Specifically, the formula for calculating and obtaining the real-time stored NH3 amount corresponding to the SCR catalyst according to the initial value of the stored NH3 amount and the real-time stored NH3 rate is as follows:
Figure GDA0002974795580000044
wherein the content of the first and second substances,
MNH3intis the initial value of the stored NH3 amount,
Figure GDA0002974795580000045
for said real-time storage of NH3 rate, MNH3LoadThe real-time stored NH3 amount.
The beneficial effect that technical scheme that this application provided brought includes:
1. the application provides a computing technology that SCR catalyst stored up NH3 volume considers the oxidation volume of NH3 gas and the NH3 ability of storing up under the SCR catalyst current operating mode, reduces the influence of interference factor to the computational result to a certain extent, improves the computational accuracy, provides the assurance for the availability of later stage catalyst conversion performance.
2. According to the method, the initial value of the stored NH3 amount is corrected and calculated, and the stored NH3 amount is oxidized and corrected, so that the calculation accuracy is further improved.
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In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a flowchart illustrating steps of a method for calculating the amount of NH3 stored in an SCR catalyst according to embodiment 1 of the present application;
fig. 2 is a flowchart of step S3 in the method for calculating the amount of stored NH3 in the SCR catalyst according to embodiment 1 of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.
The embodiment of the invention provides a method for calculating the amount of stored NH3 of an SCR (selective catalytic reduction) catalyst, which considers the oxidation amount of NH3 gas and the NH3 storage capacity of the SCR catalyst under the current working condition, reduces the influence of interference factors on a calculation result to a certain extent, improves the calculation accuracy and guarantees the availability of the conversion performance of the catalyst at the later stage.
In order to achieve the technical effects, the general idea of the application is as follows:
a method of calculating an amount of stored NH3 for an SCR catalyst, the method comprising the steps of:
s1, calculating and obtaining a final NH3 storage capacity value of the SCR catalyst according to the basic NH3 storage capacity value and the NH3 storage capacity correction coefficient of the SCR catalyst;
s2, when the ECU is electrified again, calculating and obtaining an initial value of the amount of stored NH3 of the SCR catalyst according to the initial value of stored NH3 of the SCR catalyst, the correction coefficient of the initial value of stored NH3 and the compensation amount of the initial value of stored NH 3;
s3, calculating the real-time NH3 storage rate of the SCR catalyst according to the effective NH3 injection mass flow corresponding to the SCR catalyst, the NH3 mass flow consumed by the conversion NOx, the carrier temperature, the exhaust mass flow, the carrier aging coefficient and the current NH3 storage variable quantity;
s4, calculating and obtaining real-time stored NH3 amount corresponding to the SCR catalyst according to the initial value of the stored NH3 amount and the real-time stored NH3 rate.
Example 1
Referring to fig. 1 and 2, an embodiment of the invention provides a method for calculating an amount of stored NH3 of an SCR catalyst, the method comprising the following steps:
s1, calculating and obtaining a final NH3 storage capacity value of the SCR catalyst according to the basic NH3 storage capacity value and the NH3 storage capacity correction coefficient of the SCR catalyst;
s2, when the ECU is electrified again, calculating and obtaining an initial value of the amount of stored NH3 of the SCR catalyst according to the initial value of stored NH3 of the SCR catalyst, the correction coefficient of the initial value of stored NH3 and the compensation amount of the initial value of stored NH 3;
s3, calculating the real-time NH3 storage rate of the SCR catalyst according to the effective NH3 injection mass flow corresponding to the SCR catalyst, the NH3 mass flow consumed by the conversion NOx, the carrier temperature, the exhaust mass flow, the carrier aging coefficient and the current NH3 storage variable quantity;
s4, calculating and obtaining real-time stored NH3 amount corresponding to the SCR catalyst according to the initial value of the stored NH3 amount and the real-time stored NH3 rate.
In the embodiment of the present application, in step S1, it is required to know the final NH3 storage capacity value of the SCR catalyst, i.e. the maximum value of the SCR catalyst NH3 storage capacity, and the final NH3 storage capacity value of the SCR catalyst is mainly related to the characteristics of the carrier, the temperature of the carrier, and the aging degree of the carrier;
the method comprises the steps that NH3 storage capacity of an SCR catalyst can be obtained according to a preset SCR catalyst NH3 storage capacity model, carrier temperature and carrier aging coefficient are input into the SCR catalyst NH3 storage capacity model, NH3 storage capacity of the SCR catalyst is output, in the model, a base NH3 storage capacity value of the SCR catalyst is obtained by table lookup of carrier temperature, NH3 storage capacity correction coefficient is obtained by table lookup of carrier aging coefficient, and a final NH3 storage capacity value of the SCR catalyst is a product of a base NH3 storage capacity value and an NH3 storage capacity correction coefficient.
Specifically, the final NH3 capacity value calculation formula corresponding to the final NH3 capacity value is as follows:
MNH3cap＝Mbase_NH3cap×fNH3cap(ii) a Wherein the content of the first and second substances,
MNH3capfor the final NH3 capacity value, Mbase_NH3capOn the basis of the NH3 capacity value, fNH3capThe correction coefficient is NH3 storage capacity.
Step S2, when the ECU is electrified again, the controller reads the stored NH3 initial value of the last driving cycle from the system EEPROM, obtains the correction coefficient of the stored NH3 initial value according to the table lookup of the stop running time t of the engine, obtains the compensation quantity of the stored NH3 initial value according to the table lookup of the stop running time t of the engine, and then calculates and obtains the stored NH3 initial value of the SCR catalyst according to the stored NH3 initial value, the stored NH3 initial value correction coefficient and the stored NH3 initial value compensation quantity of the SCR catalyst.
Specifically, the calculation formula of the initial value of the stored NH3 amount corresponding to the initial value of the stored NH3 amount is as follows:
MNH3int＝Mint_EEPROM×fint+Mint_offset(ii) a Wherein the content of the first and second substances,
MNH3intfor storing an initial value of NH3 quantity, Mint_EEPROMTo store the initial value of NH3, fintCorrection factor, M, for storing initial value of NH3int_offsetThe compensation amount is the initial value of NH3 storage.
And step S3, calculating the real-time NH3 storage rate of the SCR catalyst under the working condition at that time according to the effective NH3 injection mass flow corresponding to the SCR catalyst, the NH3 mass flow consumed by the conversion Nox, the carrier temperature, the exhaust mass flow, the carrier aging coefficient and the current NH3 storage variable quantity.
And step S4, calculating and obtaining real-time stored NH3 amount corresponding to the SCR catalyst according to the initial value of the stored NH3 amount and the real-time stored NH3 rate.
According to the embodiment of the application, the oxidation amount of NH3 gas and the NH3 storage capacity of the SCR catalyst under the current working condition are considered, the influence of interference factors on the calculation result is reduced to a certain extent, the calculation accuracy is improved, and the availability of the conversion performance of the catalyst at the later stage is guaranteed.
In the embodiment of the present application, the calculation accuracy is further improved by performing correction calculation on the initial value of the stored NH3 amount and performing oxidation correction on the stored NH3 amount.
Specifically, the method includes the following steps of calculating a real-time NH3 storage rate of the SCR catalyst according to an effective NH3 injection mass flow corresponding to the SCR catalyst, an NH3 mass flow consumed by NOx conversion, a carrier temperature, an exhaust mass flow, a carrier aging coefficient and a current NH3 storage variable quantity, and specifically includes the following steps:
s301, judging whether a first difference value between the effective NH3 injection mass flow and the NH3 mass flow consumed by NOx conversion is smaller than a preset first threshold value or not;
s302, when the first difference is smaller than a preset first threshold value, the residual coefficient after NH3 gas phase oxidation is 1;
s303, calculating and obtaining a stored NH3 rate after considering NH3 gas phase oxidation according to the effective NH3 injection mass flow, the NH3 mass flow consumed by the conversion Nox and the residual coefficient after NH3 gas phase oxidation;
s304, judging the numerical value of the calibration switching value;
s305, when the value of the calibrated switching value is equal to 0, the real-time NH3 storage rate is equal to the NH3 storage rate after considering NH3 gas phase oxidation;
s306, when the value of the calibrated switching value is equal to 1, the real-time NH3 storage rate is equal to the difference between the NH3 storage rate after the NH3 gas phase oxidation and the NH3 adsorption release oxidation rate.
Specifically, in step S303, the calculation formula considering the stored NH3 rate after the gas-phase oxidation of NH3 is:
Figure GDA0002974795580000091
Figure GDA0002974795580000092
effective NH3 injection mass flow,
Figure GDA0002974795580000093
NH3 Mass flow, f consumed for NOx conversionNH3o2gasIs the residual coefficient after vapor phase oxidation of NH3,
Figure GDA0002974795580000094
to take into account the stored NH3 rate after gas phase oxidation of NH 3.
Specifically, in step S305,
Figure GDA0002974795580000095
wherein the content of the first and second substances,
Figure GDA0002974795580000096
the real-time storage of the NH3 rate,
Figure GDA0002974795580000097
to take into account the stored NH3 rate after gas phase oxidation of NH 3.
Specifically, in step S306,
Figure GDA0002974795580000098
wherein the content of the first and second substances,
Figure GDA0002974795580000099
the real-time storage of the NH3 rate,
Figure GDA00029747955800000910
to account for the stored NH3 rate after vapor phase oxidation of NH3,
Figure GDA00029747955800000911
the oxidation rate is released for adsorption of NH 3.
Specifically, the method further comprises a procedure for calculating the release oxidation rate of adsorbed NH3, that is, the method further comprises the following steps:
and calculating to obtain the release oxidation rate of the adsorbed NH3 according to the adsorbed NH3 release oxidation coefficient corresponding to the aged SCR catalyst, the adsorbed NH3 release oxidation coefficient corresponding to the new catalyst, the interpolation coefficient of the adsorbed NH3 release oxidation coefficient and the exhaust mass flow.
It should be noted that the formula for calculating the release oxidation rate of adsorbed NH3 is:
Figure GDA00029747955800000912
wherein the content of the first and second substances,
fOld_NH3o2adsrelease of the oxidation coefficient, f, for the corresponding adsorbed NH3 of an aged SCR catalystNew_NH3o2adsRelease of the oxidation coefficient, f, for the corresponding adsorbed NH3 of the new catalystmap_NH3o2adsTo release an interpolation coefficient of the oxidation coefficient for adsorbed NH3,
Figure GDA00029747955800000913
in order to be able to control the exhaust gas mass flow,
Figure GDA00029747955800000914
the oxidation rate is released for adsorption of NH 3.
Further, step S302 corresponds to a corresponding operation when the first difference is smaller than a preset first threshold, and when the first difference is not smaller than the preset first threshold, the method further includes step S307, and step S307 includes the following steps:
and when the first difference value is not less than a preset first threshold value, calculating to obtain a residual coefficient after NH3 gas phase oxidation according to the NH3 gas phase oxidation coefficient corresponding to the aged catalyst, the NH3 gas phase oxidation coefficient corresponding to the new catalyst and the interpolation coefficient of the NH3 gas phase oxidation coefficient.
Due to the gas phase oxidation of NH3 under the high-temperature state of SCR, the partial oxidation is mainly influenced by the mass flow of exhaust gas and the average temperature of the SCR catalyst, and the oxidation of the partial NH3 gas influences the stored NH3 amount in the catalyst;
the input of a gas phase NH3 oxidation coefficient calculation model is SCR carrier temperature, exhaust mass flow and carrier aging coefficient, and the output is residual coefficient after NH3 gas phase oxidation, in the model, the SCR carrier temperature and exhaust flow look up a new SCR catalyst NH3 gas phase oxidation coefficient table and an aging SCR catalyst NH3 gas phase oxidation coefficient table to obtain the NH3 gas phase oxidation coefficient of the new catalyst and the NH3 gas phase oxidation coefficient of the aging SCR catalyst, then the interpolation coefficient of the NH3 gas phase oxidation coefficient is obtained according to the SCR catalyst aging coefficient table look-up, and the NH3 gas phase oxidation coefficients of the new catalyst and the aging catalyst are interpolated to obtain intermediate quantity.
Specifically, according to the NH3 gas phase oxidation coefficient corresponding to the aged catalyst, the NH3 gas phase oxidation coefficient corresponding to the new catalyst, and the interpolation coefficient of the NH3 gas phase oxidation coefficient, the calculation formula for calculating the residual coefficient after NH3 gas phase oxidation is:
fNH3o2gas＝1-[fOld_NH3o2gas+(fNew_NH3o2gas-fOld_NH3o2gas)×fmap_NH3o2gas]；
fOld_NH3o2gasNH3 vapor phase oxidation coefficient, f, for aged catalystNew_NH3o2gasThe corresponding NH3 gas phase oxidation coefficient, f of the new catalystmap_NH3o2gasInterpolation factor, f, for the NH3 gas phase oxidation factorNH3o2gasIs the residual coefficient after gas phase oxidation of NH 3.
In step S4, according to the initial value of the stored NH3 amount and the real-time stored NH3 rate, a formula for calculating and obtaining the real-time stored NH3 amount corresponding to the SCR catalyst is:
Figure GDA0002974795580000111
wherein the content of the first and second substances,
MNH3intis the initial value of the amount of stored NH3,
Figure GDA0002974795580000112
for real-time storage of NH3 rate, MNH3LoadThe NH3 amount is stored in real time.
It is noted that, in the present application, relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The foregoing are merely exemplary embodiments of the present application and are presented to enable those skilled in the art to understand and practice the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (9)

1. A method of calculating an amount of stored NH3 for an SCR catalyst, the method comprising the steps of:
calculating and obtaining a final NH3 storage capacity value of the SCR catalyst according to a basic NH3 storage capacity value and a NH3 storage capacity correction coefficient of the SCR catalyst;
when the ECU is electrified again, calculating and obtaining an initial value of the stored NH3 amount of the SCR catalyst according to the initial value of the stored NH3 of the SCR catalyst, the correction coefficient of the initial value of the stored NH3 and the compensation amount of the initial value of the stored NH 3;
calculating the real-time NH3 storage rate of the SCR catalyst according to the effective NH3 injection mass flow corresponding to the SCR catalyst, the NH3 mass flow consumed by NOx conversion, the carrier temperature, the exhaust mass flow, the carrier aging coefficient and the current NH3 storage variable quantity;
calculating and obtaining real-time stored NH3 amount corresponding to the SCR catalyst according to the initial value of the stored NH3 amount and the real-time stored NH3 rate; wherein the content of the first and second substances,
the method for calculating the real-time NH3 storage rate of the SCR catalyst according to the effective NH3 injection mass flow corresponding to the SCR catalyst, the NH3 mass flow consumed by NOx conversion, the carrier temperature, the exhaust mass flow, the carrier aging coefficient and the current NH3 storage variable quantity comprises the following steps:
judging whether a first difference value between the effective NH3 injection mass flow and the NH3 mass flow consumed by the NOx conversion is smaller than a preset first threshold value or not;
when the first difference value is smaller than a preset first threshold value, the residual coefficient after NH3 gas phase oxidation is 1;
calculating and obtaining a stored NH3 rate after considering NH3 gas phase oxidation according to the effective NH3 injection mass flow, the NH3 mass flow consumed by the conversion Nox and the residual coefficient after NH3 gas phase oxidation;
judging a numerical value of a preset calibration switching value;
when the value of the calibrated switching value is equal to 0, the real-time stored NH3 rate is equal to the stored NH3 rate after considering NH3 gas phase oxidation;
when the value of the calibrated switching value is equal to 1, the real-time stored NH3 rate is equal to the difference between the stored NH3 rate after considering NH3 gas phase oxidation and the release oxidation rate of the adsorbed NH 3.
2. The method for calculating the amount of stored NH3 of the SCR catalyst of claim 1, wherein the final stored NH3 capability value corresponding to the final stored NH3 capability value is calculated by the formula:
MNH3cap＝Mbase_NH3cap×fNH3cap(ii) a Wherein the content of the first and second substances,
MNH3capfor the final NH3 storage capacity value, Mbase_NH3capOn the basis of the NH3 capacity value, fNH3capThe correction coefficient is NH3 storage capacity.
3. The method for calculating the stored NH3 amount of the SCR catalyst as claimed in claim 1, wherein the stored NH3 amount initial value corresponding to the stored NH3 amount initial value is calculated by the formula:
MNH3int＝Mint_EEPROM×fint+Mint_offset(ii) a Wherein the content of the first and second substances,
MNH3intis the initial value of the amount of stored NH3, Mint_EEPROMIs the initial value of NH3 storage, fintCorrecting the coefficient for the initial value of stored NH3, Mint_offsetAnd compensating the initial value of the stored NH 3.
4. The method of calculating the amount of stored NH3 for an SCR catalyst of claim 1, further comprising the steps of:
and when the first difference value is not less than a preset first threshold value, calculating to obtain the residual coefficient after the NH3 gas phase oxidation according to the NH3 gas phase oxidation coefficient corresponding to the aged catalyst, the NH3 gas phase oxidation coefficient corresponding to the new catalyst and the interpolation coefficient of the NH3 gas phase oxidation coefficient.
5. The method of calculating the amount of stored NH3 for an SCR catalyst of claim 1, further comprising the steps of:
and calculating to obtain the release oxidation rate of the adsorbed NH3 according to the release oxidation coefficient of the adsorbed NH3 corresponding to the aged SCR catalyst, the release oxidation coefficient of the adsorbed NH3 corresponding to the new catalyst, the interpolation coefficient of the release oxidation coefficient of the adsorbed NH3 and the exhaust mass flow.
6. The method for calculating the amount of stored NH3 for an SCR catalyst of claim 1, wherein the calculation formula that considers the stored NH3 rate after gas phase oxidation of NH3 is:
Figure FDA0002974795570000031
Figure FDA0002974795570000032
is the effective NH3 injection mass flow,
Figure FDA0002974795570000033
NH3 Mass flow, f consumed for the conversion of NoxNH3o2gasFor the residual coefficient after vapor phase oxidation of NH3,
Figure FDA0002974795570000034
the stored NH3 rate after gas phase oxidation of NH3 is considered.
7. The method for calculating the amount of stored NH3 of the SCR catalyst as recited in claim 4, wherein the calculation formula for calculating the residual coefficient after NH3 gas phase oxidation according to the interpolation coefficients of the NH3 gas phase oxidation coefficient corresponding to the aged catalyst, the NH3 gas phase oxidation coefficient corresponding to the new catalyst and the NH3 gas phase oxidation coefficient is as follows:
fNH3o2gas＝1-[fOld_NH3o2gas+(fNew_NH3o2gas-fOld_NH3o2gas)×fmap_NH3o2gas]；
fOld_NH3o2gasthe corresponding NH3 gas phase oxidation coefficient f of the aging catalystNew_NH3o2gasThe corresponding NH3 gas phase oxidation coefficient f of the new catalystmap_NH3o2gasIs an interpolation factor of the NH3 vapor phase oxidation factor, fNH3o2gasIs the residual coefficient after the gas phase oxidation of the NH 3.
8. The method for calculating the stored NH3 amount of the SCR catalyst of claim 5, wherein the formula for calculating the release oxidation rate of the adsorbed NH3 according to the adsorbed NH3 release oxidation coefficient corresponding to the aged SCR catalyst, the adsorbed NH3 release oxidation coefficient corresponding to the new catalyst, the interpolation coefficient of the adsorbed NH3 release oxidation coefficient and the exhaust mass flow is as follows:
Figure FDA0002974795570000035
wherein the content of the first and second substances,
fOld_NH3o2adsreleasing an oxidation coefficient, f, for the adsorbed NH3 corresponding to the aged SCR catalystNew_NH3o2adsReleasing the oxidation coefficient, f, for the adsorbed NH3 corresponding to the new catalystmap_NH3o2adsAn interpolation coefficient for the adsorbed NH3 release oxidation coefficient,
Figure FDA0002974795570000036
for the purpose of the exhaust gas mass flow,
Figure FDA0002974795570000037
releasing the oxidation rate for the adsorbed NH 3.
9. The method for calculating the stored NH3 amount of the SCR catalyst as claimed in claim 1, wherein the formula for calculating the real-time stored NH3 amount corresponding to the SCR catalyst according to the initial value of the stored NH3 amount and the real-time stored NH3 rate is as follows:
Figure FDA0002974795570000041
wherein the content of the first and second substances,
MNH3intis the initial amount of the stored NH3The value of the initial value is set,
Figure FDA0002974795570000042
for said real-time storage of NH3 rate, MNH3LoadThe real-time stored NH3 amount.
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