Control method for improving precision of urea pump

Abstract

The invention provides a control method capable of improving injection precision of a urea pump obviously, and particularly relates to the urea pump used for metering based on the stepping motor principle. The injection amount and the rotating speed of a motor are in positive correlation, namely the higher the rotating speed of the motor the larger the injection amount of urea. According to the method, the corresponding relation is adopted, the closed-loop control method is utilized, control precision of the urea pump can be improved by means of primary calibration, measurement, fine calibration and repeated measurement, and therefore the precision of the actual urea injection amount and required urea injection amount is realized.

Description

technical field [0001] The invention relates to a control method of vehicle-mounted equipment, in particular to a control method applied to a urea injection system and improving the precision of a urea pump. Background technique [0002] With the continuous improvement of people's awareness of environmental protection and the continuous tightening of air pollutant control regulations, my country's requirements for vehicle exhaust emissions are becoming more and more stringent. To meet emission standards, De-NO x The application of after-treatment catalytic converters is becoming more and more extensive, especially for heavy-duty diesel vehicles NO x In the field of emission control, it is common practice to install a set of Urea-SCR (Selective Catalytic Reduction) or NH after the exhaust pipe. 3 -SCR after-treatment system to solve NO x emission problem. [0003] Thanks to NH 3 Not easy to store and potential safety hazard, Urea-SCR has become the mainstream De-NO x Po...

AI Technical Summary

Problems solved by technology

At the same time, the insufficient control precision of the urea pump is likely to cause the crystallization of the SCR system

[0005] As the core component of the SCR system, the urea pump can be divided into air-assisted type and non-air-assisted type. Regardless of the method used, a stepping motor (an open-loop control unit that converts electrical pulse signals into angular displacement or linear displacement) is used. Motor parts) is a common driving form. Since the existing technology is usually open-loop control, the urea pump is often used directly after passing the initial standard, which cannot meet the injection accuracy requirements.

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