Detecting method for ammonia leakage in post-processing system and controller of post-processing system

Abstract

The invention specifically relates to a detection method for ammonia leakage in an aftertreatment system and a controller of the aftertreatment system. The detection method comprises the steps of: controlling an SCR of the aftertreatment system to inject urea or reducing agent ammonia into the exhaust gas of a vehicle when detecting a working condition; Control the ammonia-nitrogen ratio of urea or reducing agent ammonia to exhaust gas to be less than 1, and calculate the first conversion efficiency of SCR; according to the fact that the first conversion efficiency is within the first conversion efficiency threshold, control the ammonia-nitrogen ratio of urea or reducing agent ammonia to exhaust gas not less than 1, and calculate the second conversion efficiency of the SCR; according to the fact that the second conversion efficiency is less than the second conversion efficiency threshold, it is determined that ammonia leakage occurs in the aftertreatment system. The method for detecting ammonia leakage in an aftertreatment system provided by the present invention can determine that the SCR is in a normal working state by the fact that the first conversion efficiency is within the first conversion efficiency threshold, so as to reduce the influence of the abnormal SCR on the ammonia leakage. Second, the conversion efficiency determines whether ammonia leakage occurs in the aftertreatment system.

Description

technical field [0001] The invention relates to the technical field of vehicles, in particular to a method for detecting ammonia leakage in an aftertreatment system and a controller of the aftertreatment system. Background technique [0002] This section provides merely background information related to the present disclosure and is not necessarily prior art. [0003] The aftertreatment system of the existing vehicle uses SCR (Selective Catalytic Reduction Technology), under the action of the catalyst, the reducing agent ammonia or urea is injected into the exhaust gas of the vehicle, and the NOx in the exhaust gas is reduced to N through the reducing agent ammonia or urea. 2 and H 2 O, however, if there is an abnormality in the aftertreatment system, the ammonia in the reducing agent or urea may leak, that is, a part of the ammonia in the reducing agent or urea is discharged to the atmosphere without reacting with NOx. , causing air pollution. [0004] In order to detect...

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Problems solved by technology

[0003] The post-treatment system of existing vehicles uses SCR (Selective Catalytic Reduction Technology), and under the action of the catalyst, injects the reducing agent ammonia or urea into the exhaust gas of the vehicle, and reduces the NOx in the exhaust gas to N through the reducing agent ammonia or urea. 2 and H 2 O, however, in the case of an abnormality in the aftertreatment system, the reducing agent ammonia or ammonia in urea will leak, that is, part of the reducing agent ammonia or ammonia in urea will be discharged into the atmosphere without reacting with NOx cause air pollution

[0004] In order to detect whether ammonia leakage occurs in the after-treatment system, the conversion efficiency of NOx by SCR (technology) is usually used to judge whether ammonia leakage occurs in the after-treatment system. However, both SCR failure and ammonia leakage in the after-treatment system will affect the conversion efficiency of NOx , therefore, there is a certain error in judging the leakage of ammonia in the aftertreatment system through the conversion efficiency of NOx

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