Method, device, equipment and medium for obtaining engine nitrogen oxide model value

Abstract

The present application discloses a method, device, equipment and medium for obtaining model values ​​of nitrogen oxides of an engine. The method includes: estimating the volume flow rate of the engine exhaust gas in real time; querying the delay time according to the volume flow rate; performing time delay on the original nitrogen oxide value according to the delay time to obtain the delayed nitrogen oxide value; calculating the change of the delayed nitrogen oxide value rate; compare the rate of change with the preset calibration coefficient to obtain the comparison result; select the filter coefficient according to the comparison result, and use the selected filter coefficient to filter the delayed nitrogen oxide value; use the selected time coefficient to filter the delay Perform PT filter processing on the nitrogen oxide value in real time. With the method of the embodiment of the present application, the nitrogen oxide model value obtained by processing is more in line with the actual situation, and the urea injection is more reasonable, which further reduces emissions and reduces the failure rate of the after-treatment SCR, without adding additional sensors, making the nitrogen oxide model Values ​​are more precise.

Description

technical field [0001] The present application relates to the technical field of engines, and in particular to a method, device, equipment and medium for obtaining engine nitrogen oxide model values. Background technique [0002] SCR (Selective Catalytic Reduction, Selective Catalytic Reduction) technology is one of the necessary technologies for diesel engines at present. The urea injection system injects urea reasonably according to the NOx emitted by the engine, and the urea is further decomposed into NH at high temperature 3 , under the action of SCR catalyst NH 3 Chemically react with NOx. NOx, namely nitrogen oxides, is one of the main pollutants emitted by diesel engines, mainly composed of NO and NO2. The SCR device is a post-processing device for reducing NOx emissions, and can inject urea according to the amount of NOx emitted by the engine. [0003] The amount of NOx emitted by the engine determines the amount of urea injection. At present, considering factors ...

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Problems solved by technology

[0004] The basic structure of NOx prediction models commonly used in engineering currently includes modules with steady-state NOx pulse and transient correction functions. Most of the current model values ​​have no or only simple signal processing functions (for example: simple PT filter form), resulting in the final There is still a large difference between the calculated NOx model value and the actual NOx value. Due to the lack of scientific and accurate signal processing methods, the NOx model value under transient conditions does not conform to the actual situation, especially under the strong transient condition of the engine. As a result, the post-treatment urea injection is relatively extensive, further causing problems such as substandard emissions or even crystallization

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