OBD diagnosis and treatment method of diesel engine SCR aftertreatment system

Abstract

The invention provides an OBD diagnosis and treatment method of a diesel engine SCR aftertreatment system. The SCR aftertreatment system comprises an SCR catalyst, a urea nozzle, an upstream NOx sensor, an upstream NH3 sensor, an upstream temperature sensor, a downstream NOx sensor, a downstream NH3 sensor and a downstream temperature sensor, wherein the urea nozzle, the upstream NOx sensor, the upstream NH3 sensor and the upstream temperature sensor are located on the upstream portion of the SCR catalyst, the downstream NOx sensor, the downstream NH3 sensor and the downstream temperature sensor are located on the downstream portion of the SCR catalyst, and the OBD diagnosis and treatment method comprises following steps that S1, an SCR catalyst chemical reaction dynamical model is built;S2, an SCR catalyst temperature model is built; S3, a self-adaptation sliding-mode observer is built; S4, an OBD system is subject to stage treatment. According to the OBD diagnosis and treatment method, through the stage treatment strategy, the failure diagnosis precision can be obviously improved, the emission regulation need of the nation V or higher can be met, an engine is subject to torque limiting, sensor measuring value is replaced with model calculation value, normal running of the system is ensured, and the better control effect is achieved.

Description

technical field [0001] The invention relates to the technical field of post-processing of diesel engines, in particular to an OBD diagnosis and processing method of an SCR post-processing system of a diesel engine. Background technique [0002] The focus of diesel engine emission control is NOx and particulate matter (Particulate Matter, PM) emissions. In order to reduce emissions, Selective Catalytic Reduction (Selective Catalytic Reduction, SCR) post-treatment technology has been developed rapidly. The use of SCR technology not only has small changes to the engine body, but also has good durability and can effectively reduce emissions. It has been vigorously developed and widely used at home and abroad. However, the existing model-based On-Board Diagnostics (OBD) method cannot meet the requirements of China V or higher emission regulations. When the SCR after-treatment system fails, it can only limit the torque of the engine. It is not conducive to the promotion and appli...

AI Technical Summary

Problems solved by technology

However, the existing model-based On-Board Diagnostics (OBD) method cannot meet the requirements of China V or higher emission regulations. When the SCR after-treatment system fails, it can only limit the torque of the engine. It is not conducive to the promotion and

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