Development Of Diesel Engine Noise Test System And Research On Noise Source Analysis

The noise acquisition and analysis system is an important method for the research of vehicle noise control.However,it is often expensive and inconvenient to carry.This study uses noise source analysis,signal time and frequency domain feature extraction methods,experimental analysis methods,and noise acquisition and analysis systems and other research content.Analysis of the advantages of test analysis methods and time-frequency domain feature extraction methods,and based on NI and LabVIEW software and hardware development noise acquisition and analysis system,with a simple and practical,portable features,can test and analysis of vehicles and the key parts of diesel engines the noise changes.The dissertation focuses on noise signal characteristics,noise acquisition and analysis system development,and experimental analysis and application.The main research contents are described as follows:Firstly,the noise source and noise generation mechanism of diesel engine are studied.The feature extraction methods in noise time domain,frequency domain and time-frequency domain are analyzed,and the main test methods of diesel engine noise are analyzed.By comparing the advantages and disadvantages of the signal feature extraction method and the experimental analysis method,the noise analysis process combining the test analysis with the time-frequency domain analysis is determined,which lay the foundation for the subsequent development of noise and analysis systems based on NI and LabVIEW software and hardware development.Secondly,development and research of noise collection and analysis system: On the one hand,focused on noise development and analysis system hardware development.According to the hardware design scheme of the noise collection system,the system hardware selection,signal conditioning circuit,data acquisition card selection,main indicators of the data acquisition equipment,and the connection method of the tested signal are studied,and it is analyzed that the hardware design can meet the requirements.On the other hand,the software development of the noise acquisition and analysis system is focused on.Based on the software's overall program design scheme of the noise acquisition system,the software module design of the noise collection system is carried out,mainly including the data acquisition main module design and the parameter setting sub-module design and data management module design,calibration sub-module design,software interface and results display module design and other aspects of the study,and completed the software program main sub-module debugging analysis;the other hand,the use of MATLAB tool bag in signal analysis of the advantages.Based on LabVIEW and MATLAB,the noise signal wavelet analysis module is developed and designed.The analysis module can call the wavelet analysis result and enrich the signal analysis and processing functions of the noise acquisition and analysis system.Finally,the signal acquisition,analysis and processing functions of the noise collection and analysis system are analyzed in detail,and the noise signal can be quickly calculated in terms of RMS value,waveform index,peak index,and frequency spectrum characteristics.and Tests on diesel noise and vehicles internal and external noise,on-board post-processor noise,and other aspects fully reflect the simple,practical,and portable nature of the noise acquisition system developed in this study,and enable rapid evaluation of the noise status of the test object.The analysis verified the signal acquisition and signal analysis processing capabilities of the noise acquisition and analysis system.The noise collection and analysis system designed by the dissertation has the characteristics of friendly man-machine interaction interface,simple operation,portable,and strong versatility.It can provide a good technical means for the complex testing environment of the vehicle and diesel engine.