Ageing correction method based on dual NOx sensors for SCR catalyst

Abstract

The invention provides an ageing correction method based on dual NOx sensors for an SCR (Selective Catalytic Reduction) catalyst. The NOx sensors are correspondingly arranged at the upstream and downstream of the SCR catalyst of an engine exhaust system to calculate actual conversion efficiency of the SCR catalyst in real time, and the degree of ageing of the catalyst is calculated according to the actual conversion efficiency and ideal conversion efficiency of the SCR catalyst; the feed-forward control quantity of urea is corrected according to the degree of ageing of the catalyst; the brakespecific NOx emission of an engine is calculated in real time; and an OBD (On Board Diagnostics) diagnostic strategy judgment method is provided based on an OBD emission limit. The degree of ageing ofthe catalyst is reflected by a deterioration factor of the catalyst, the ejection amount of urea can be fed back and corrected according to the degree of ageing of the catalyst, the brake specific NOx emission of a vehicle on road is calculated in real time, and an emission OBD monitoring and judging method is put forward.

Description

technical field [0001] The invention belongs to the technical field of tail gas emission of motor vehicles, in particular to an SCR catalyst aging correction method based on double NOx sensors. Background technique [0002] With the society's increasing demand for motor vehicles, the low fuel consumption and high efficiency of diesel engines are favored by the society. In the face of high nitrogen oxide emissions from diesel engines, many technologies have emerged to improve emissions and reduce pollution. Among them, Selective Catalytic Reduction (SCR), which uses ammonia generated by urea decomposition as a reducing agent, has become a common technology for improving emissions. In fact, the high temperature environment generated by the engine under high load, as well as the sulfur components in the fuel and engine oil additives acting on the SCR catalyst for a long time will lead to a decrease in its activity. Especially in the post-treatment system where the DPF is place...

AI Technical Summary

Problems solved by technology

The disadvantage of this approach is that the NOx emission data of the engine needs to be obtained through the MAP look-up table method, and the calibration workload in the development process is very large, and this method is affected by the engine operating conditions, and cannot achieve good results under transient operating conditions. ground follow control effect

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