用于柴油车尾气处理的尿素喷射泵监控系统

华中科技大学硕士学位论文

Abstract

Giving its higher thermal efficiency and lower CO2 emission,diesel vehicle has beengot a wide range of application all over the world,however the air pollution caused by itsexhaust NOx and particulate matter has been becoming more and more serious. So withmore and more strict emission regulations of diesel engine, selective catalytic reduction(SCR)exhaust after-treatment technology of diesel engine has been considered to be themost promising one,due to its good flue economy and insensitiveness to sulfur,and it alsohas been widely applied in many European countries. In recent years, our country hasbeen popularizing its application in diesel engine.The control of urea dosing is key toSCR system, so a urea pump monitor system with a human-machine interface based onSTM32 is developed in this paper to meet the requirements of urea dosing control unit.

This paper mainly introduces the hardware and software design of STM32 controlpanel and the development of the human-machine interface. STM32 control panel canacquire the related data from temperature sensors and pressure sensors in real-time andmonitor/control the switch states of electromagnetic valve and relay simultaneously.Thehuman-machine interface developed by VC can display the sampling data receivedfrom STM32 panel in curve and send commands to control the stepper motor andelectromagnetic valve of STM32 panel.The data and commands are transmitted betweencomputer and STM32 control panel through RS232 bus.

Firstly,according to the working principle of SCR, the overall design scheme of ureapump monitor system based on ARM microprocessor is proposed in this paper. In thehardware prospective, the design thought of the key circuit modules and matters neededattention is discussed. The configuration process and actual application of variousperipheral module of STM32 from the software prospective is introduced. Secondly,Modbus communication protocol based on standard bus RS232 to realize the real-timecommunication between computer and STM32 panels is proposed. Define thecommunication frame of each modules and design the sending, receiving andcommunication programs to ensure communication reliable and stable. Last, thehuman-machine interface is built, and the establishment of each functional module ofinterface and function realization is introduced, furthermore the transmission of data andcommands between computer and STM32 panel is realized by serial programming.Key wo rd:S C R,VC ,mo nitor s ystem,S TM32,RS 232,Modb us pro toco l

II