A T3 metering theory used for diesel exhaust fluid dosing and failure diagnosis in selective catalyst reduction dosing systems

• Published in: Journal of Zhejiang University. A. Science Vol. 20; no. 5; pp. 334 - 346
• Main Authors: Yang, Yan-xiang, Tan, Bing-qian, Liu, Chang-wen, Zhang, Ping, Le, Qi-jiang, Zhang, Ben-xi
• Format: Journal Article
• Language: English
• Published: Hangzhou Zhejiang University Press 01.05.2019; Springer Nature B.V
• Subjects: Catalysis; Catalysts; Civil Engineering; Classical and Continuum Physics; Control methods; Correlation analysis; Diagnosis; Diesel; Diesel engines; Emissions control; Energy conservation; Engineering; Exhaust emission; Exhaust emissions; Exhaust systems; Failure analysis; Failure modes; Industrial Chemistry/Chemical Engineering; Mathematical models; Mechanical Engineering; Nozzles; Position measurement; Pulse duration modulation; Selective catalytic reduction; Plunger-sleeve pump; 尿素溶液计量单元; T3 计量理论; Diesel exhaust fluid (DEF) dosing unit; T3 metering theory; TK421.5; Sensor-free diagnosis; 套筒式柱塞泵; 无传感器诊断
• ISSN: 1673-565X; 1862-1775
• DOI: 10.1631/jzus.A1800518

In this paper, a new dosing unit is presented for diesel exhaust fluid (DEF) dosing in combustion engine exhaust emission selective catalyst reduction (SCR) systems. The dosing unit is a plunger-sleeve pump nozzle system driven by a charged solenoid, and is pump-end controlled by pulse width modulation (PWM) signals. The core characteristics of the unit include both metering precision control and failure diagnosis methods. In this study, both physical-mathematical analysis and experiments were carried out. A so-called whole state T3 metering theory was developed by studying the system using a physical-mathematical model based on energy conservation. The study showed that the liquid discharge, which is associated with the plunger-sleeve relative position, correlates well with a measurable variable T3. Experimental investigations verified that the metering results were independent of the state variations in some range and that metering is controlled with high precision. Two typical DEF dosing systems based on the dosing unit and some specific failure modes are introduced. Significant variation of the parameter T 3 in the T3 model is useful for the detection of specific failure modes.