Urea injection control method capable of meeting NOx emission control of in-use vehicle

Abstract

The invention discloses a urea injection control method capable of meeting NOx emission control of an in-use vehicle. According to the method, an air inlet flow sensor is arranged on an air inlet pipeline of an engine, an upstream NOx sensor, and an upstream exhaust temperature sensor are sequentially arranged on an upstream exhaust pipe of an SCR catalyst, a downstream NOx sensor and a downstreamexhaust temperature sensor are arranged on a downstream exhaust pipe of the SCR catalyst, an SCR controller calculates the basic urea required injection amount according to signals of the sensors andthe set target NOx conversion rate, and a urea pump and a nozzle are controlled to execute urea injection. Relevance between the SCR control and an ECU is completely decoupled, the SCR system can work completely independent of an engine, generality is high, an engine rack or complete vehicle test can be reduced, a large amount of manpower and material resources are saved, the efficiency of end in-use vehicle modification is improved, and the environment treatment pace is quickened.

Description

technical field [0001] The invention relates to the technical field of post-treatment of diesel engine exhaust, in particular to a urea injection control method satisfying NOx emission control of in-use vehicles. Background technique [0002] The traditional SCR control technology is based on the advanced bench calibration of the target engine to obtain information such as exhaust flow, exhaust temperature and NOx concentration under various working conditions, and save these basic data in the controller; when the vehicle is running , and then according to the engine operating conditions at that time, look up the table from the calibration data to estimate the exhaust flow, exhaust temperature and NOx concentration at that time, and then calculate the required urea injection amount. Due to the special circumstances of the in-use vehicle, the engine cannot be disassembled for bench testing, so the required injection volume of urea cannot be calculated based on the pre-calibra...

AI Technical Summary

Problems solved by technology

Due to the special circumstances of the vehicle in use, the engine cannot be disassembled for a bench test, so it is impossible to calculate the required injection volume of urea based on the pre-calibrated data, and the traditional technology cannot be applied

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