Development Of Combustion Analysis System For Internal Combustion Engine Based On STM32 Single Chip Microcomputer

Combustion analysis system of internal combustion engine is a key tool to study combustion process of internal combustion engine.It calculates combustion characteristic parameters such as heat release rate,temperature and combustion speed by collecting transient cylinder pressure data,and provides theoretical guidance for the design and development of internal combustion engine.Although the combustion engine analysis system has been developed by the famous overseas research and development of internal combustion engine,it is expensive.Most of the data acquisition equipments of the combustion analysis system developed by domestic universities use commercial data acquisition cards,and the combustion analysis software is developed in Lab VIEW or C++language,which results in complicated wiring,insufficient number of acquisition channels and unfriendly operation interface.In recent years,embedded technology has been developing rapidly,especially the function of ARM microprocessor has been improved rapidly.It is possible to design and develop data acquisition circuit for internal combustion engine based on ARM microprocessor.This paper designs a data acquisition device for internal combustion engine test by using STM32F103ZET6 chip in ARM microprocessor.The key circuit design includes voltage follower receiving charge amplifier output signal module,voltage comparator receiving photoelectric pulse signal module,voltage follower and differential amplifier receiving temperature signal module.And the voltage follower receives the piezoresistive pressure sensor signal module.Cylinder pressure sensor is responsible for collecting cylinder pressure data and transmitting analog signal to charge amplifier.The data acquisition equipment collects charge amplifier amplification signal synchronously according to photoelectric pulse signal.At the same time,the temperature and pressure of intake and exhaust,the temperature and pressure of engine oil,and the temperature of cold cut water outlet are collected.The operation program of data acquisition is developed to realize multi-channel analog-to-digital conversion,external interruption,serial communication and other functions.Combustion analysis software is developed based on C_#programming language,which uses iterative method to calculate heat release rate,has the functions of serial communication,data averaging and smoothing,Excel file saving data and so on.In order to verify the rationality of the design of the system,the heat release rate and accumulated heat release of the system are compared with the combustion analyzer developed by Devectron Company.The results show that the peak value of exothermic rate obtained by this system is slightly lower than the peak value of the exothermic rate of Devectron,and the exothermic rate in the post-combustion period is slightly higher than that of Devectron;the exothermic starting point and exothermic law are basically consistent with that of Devectron;the accumulated exothermic heat is slightly higher than the accumulated exothermic heat of Devectron,but it is closer to the theoretical The measurement and calculation results are accurate and reliable.