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Method for calculating ammonia leakage amount of SCR post-processing system

A calculation method, ammonia leakage technology, applied in the direction of exhaust treatment, electronic control of exhaust treatment device, diagnostic device of exhaust treatment device, etc., can solve the problem of low accuracy of SCR closed-loop control, and achieve accurate SCR closed-loop control , Improve the accuracy and reduce the effect of crystallization

Active Publication Date: 2021-08-03
DONGFENG AUTOMOBILE COMPANY
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Problems solved by technology

[0004] The purpose of the present invention is to overcome the defects and problems of low accuracy of SCR closed-loop control existing in the prior art, and provide a calculation method for ammonia leakage of SCR post-treatment system that improves the accuracy of SCR closed-loop control

Method used

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  • Method for calculating ammonia leakage amount of SCR post-processing system
  • Method for calculating ammonia leakage amount of SCR post-processing system
  • Method for calculating ammonia leakage amount of SCR post-processing system

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Embodiment

[0061] see figure 1 , a method for calculating ammonia leakage in an SCR aftertreatment system, the method comprising the following steps:

[0062] S1. Obtain the relational expression between the measured value of the current downstream NOx sensor and the amount of ammonia leakage;

[0063] The downstream NOx sensor measurement consists of nitrogen oxides and ammonia slip as shown in the following formula:

[0064] NO X _out=NO X +NH 3

[0065] The amount of nitrogen oxides is obtained by the following formula:

[0066] NO X = NO X _indly×(1-K×η)

[0067] In the above formula, NO X is the amount of nitrogen oxides;

[0068] From the above two formulas, the relationship can be obtained as:

[0069] NO X _out=NO X _indly×(1-K×η)+NH 3

[0070] In the above formula, NO X _out is the measured value of the current downstream NOx sensor, NO X _indly is the measured value of the upstream NOx sensor before t time (t is the time required for gas to flow from the upstr...

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Abstract

The invention discloses a method for calculating the ammonia leakage rate of an SCR post-processing system. The method comprises the following steps that S1, a relational expression between a current downstream NOx sensor measurement value and the ammonia leakage rate is obtained; S2, a relational expression between a downstream NOx sensor measurement value before 1s and the ammonia leakage amount is obtained; S3, the current ammonia leakage amount is calculated; a calculated value of the ammonia leakage amount is processed through low-pass filtering; the calculated value of the ammonia leakage amount is corrected according to the change trend of the calculated value of the ammonia leakage amount and an ammonia leakage amount actual value; and when the NOx conversion efficiency obtained through an upstream NOx sensor measurement value and the downstream NOx sensor measurement value is larger than a threshold value, the ammonia leakage amount calculation value is set to be 0. According to the design, the precision of SCR closed-loop control is improved, and the calculation accuracy of the ammonia leakage rate is high.

Description

technical field [0001] The invention relates to the technical field of SCR post-processing, in particular to a calculation method for ammonia leakage in an SCR post-processing system, which is mainly suitable for improving the accuracy of SCR closed-loop control. Background technique [0002] As a kind of power machinery, diesel engine has made outstanding contributions to the development of society, but it also causes environmental pollution. With the upgrading of my country's automobile emission standards, automobile emission regulations are more stringent after entering the National VI emission stage, and the requirements for diesel engine emission technology are getting higher and higher. It is becoming more and more difficult to achieve emission compliance by simply improving engine technology. In this case, an SCR aftertreatment system (such as figure 2 shown). The basic working principle of the SCR after-treatment system is: the exhaust gas flows out from the turboch...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F01N3/20F01N11/00F01N9/00
CPCF01N3/208F01N11/00F01N2610/02F01N2560/026Y02T10/40
Inventor 卢勇董波王善元华岳崔巍吴家坤张勃石磊孙哲秦忠怀张孝李楚桥沈昊杨勇杜雨婷
Owner DONGFENG AUTOMOBILE COMPANY
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