Design And Realization Of Electronic Control Unit For Diesel Engine SCR Aftertreatment Urea Injection

In recent years,China has promulgated a series of laws and regulations to raise the limit of pollutant emission limits,which has gradually reduced the emission hazards of pollution sources such as motor vehicles and power plants.However,with the increase in the number of motor vehicles and the increase in the degree of mechanization of agriculture,forestry,engineering construction,etc.The number of diesel engines has also increased,and its exhaust emissions will inevitably cause some pollution to the atmospheric environment.In order to protect the planet on which human beings live,countries have promulgated diesel engine emission limit regulations in line with national conditions to limit diesel engine exhaust emissions.Among the harmful emissions of diesel engines,NO_x emissions are the main pollutants.After comprehensive comparative analysis of diesel engine emission control technology,selective catalytic reduction technology has matured in China and meets the needs of the Chinese market.Based on the existing SCR(Selective Catalytic Reduction Technology)system,this paper optimizes its electrical control system to meet the current national NO_x emission pollutant limit requirements and achieve the treatment of NO_x in the emission pollutants.Based on the V-shaped development model commonly used in the automotive industry and the idea of modular development,this paper develops an efficient electronic control unit for an air-assisted SCR system.The ACU(Aftertreatment Control Unit)realizes the control of the urea pump by collecting signals such as speed,NO_x value,catalyst temperature,etc.Through upper-layer control strategies and standard protocols,and then precisely controls the injection of urea solution to achieve reasonable treatment of exhaust gas emissions.the goal of.The main research and completion of this article are as follows:First,analyzed domestic and foreign diesel engine emission control technology,identified the air-assisted SCR system as the research direction,introduced the composition of the SCR system in detail,and gave requirements for the selection of components such as NO_x sensors and temperature sensors.At the same time,based on the analysis of the working principle and reflection principle of the selected urea pump,a corresponding upper control strategy was formulated.The upper-layer control strategy model is built by Matlab/Simulink,and the corresponding control strategy code is generated to realize the efficiency and convenience of code writing.Second,the functional requirements of the ACU control unit are analyzed,the hardware design of the electronic control unit is completed,and the design of the microcontroller module,power supply module,sensor processing circuit module and CAN communication module are elaborated in detail.At the same time,considering the harsh environment in which the equipment is located,the ACU control unit is optimized for circuit protection and electromagnetic compatibility to ensure its stability and safety.Third,analyze the functional requirements of the ACU software and complete the layered and modular design of the software.First,based on the Codewarrior IDE(Integrated Development Environment)integrated development environment,the underlying drivers such as CAN communication,ADC acquisition,and watchdog are designed,and the Free RTOS system is combined with the underlying drivers to complete the optimized design of the underlying drivers.Secondly,based on the Visual Studio 2019 development environment,the upper computer calibration software is written and completed.Its functions include monitoring the information collected by the urea pump and ACU,and modifying the exhaust flow rate and injection factor.Fourth,the test method and test process are designed to make the SCR system meet reasonable control logic under the existing experimental conditions,and complete the test of hardware PCB board welding,voltage circuit,BMD interface and CAN communication.The test results show that the developed SCR electronic control unit has stable hardware functions,high safety,strong anti-interference ability,reliable design of the bottom driver software,upper-layer calibration software can monitor and calibrate the parameters in real time,the SCR system can quickly respond to the injection,and the amount of urea solution injection High accuracy.Therefore,the designed ACU control unit has certain application value.