Design And Development Of A Real-time Analysis System For Diesel Engine Heat Release Rate

This article mainly introduces the realization of the adaptive filtering method in the online acquisition process of cylinder pressure signal and the development of the on-line collection and real-time combustion analysis system for the cylinder pressure signal of the internal combustion engine.In order to obtain real and effective internal cylinder pressure data of the internal combustion engine,this article aims at measuring the channel effect in the process of measuring cylinder pressure data.Based on the formants in spectrum analysis of dynamometer charts,the combination of filtering methods such as FFT,linear interpolation and IDFT is used to realize acquisition.In-cylinder pressure real-time filtering,this method can effectively remove clutter interference,to maximize the preservation of the real pressure data in the cylinder combustion start phase and maximum pressure increase rate and other combustion characteristics,help to improve the accuracy of the calculation of combustion heat release rate.In addition,under different operating conditions of the internal combustion engine,the interference frequency is different,the system can realize on-line adaptive recognition and search of formant frequency range,effectively avoiding the problem of difficult setting of cut-off frequency in the general digital filtering method.This paper uses a data acquisition card,cylinder pressure sensor,angle sensor and LabVIEW software to build a combustion analysis test platform.In this measurement platform,the square wave pulse signal of the angular mark sensor is used as an external acquisition clock to trigger the data acquisition card,and the cylinder pressure signal is acquired online in units of 0.1 degree phase angle.The acquisition platform uses the pure compression line method and the compression midline method to achieve the dynamic top dead center calibration and correction,and the application of online adaptive filtering method to achieve the smooth processing of cylinder pressure data;at the same time based on the power diagram calculation of the maximum pressure of the internal combustion engine Important combustion parameters such as high rate,combustion heat release rate,CA50,explosion pressure,and their corresponding phases;using producer/consumer operation patterns with good synchronization in the program algorithm to improve data sharing capabilities and achieve real-time data operations simultaneously Store results quickly.Finally,by analyzing the proportion of computing time of each sub-program module in the test platform,it is concluded that the real-time performance of the system is closely related to the average number of processing cycles of the cylinder pressure data.When the cycle is n,it can meet the real-time calculation at the speed of n*1900r/min,which can meet the requirements of most diesel combustion analysis.Through the above two parts of work,this article can obtain more accurate in-cylinder pressure data,and real-time reduction of the actual combustion state of the internal combustion engine cylinder with on-line measurement and real-time analysis modes.At the same time,the combustion analysis system can reflect the transient characteristics of the engine in real time.