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Coherent Analysis of vehicle HVAC Using the MDSA Method  

Oh Jae-Eung (한양대학교 기계공학부)
Hwang DongKun (한양대학교 자동차공학과)
Abu Aminudin (한양대학교 자동차공학과)
Lee Jung-Youn (경기대학교 기계시스템디자인공학부)
Kim SungSoo (현대모비스 응용기술연구부)
Publication Information
Journal of the Korean Society for Precision Engineering / v.22, no.8, 2005 , pp. 143-150 More about this Journal
Abstract
To verify applicability of multi-dimensional spectral analysis (MDSA) fur noise source identification two different approaches which are frequency response and coherent function have been investigated. The coherence function approach appears able to separate the correlated system when the noise sources were coherent. In this study, we identify contribution of structure-borne-noise of vehicle HVAC system using MDSA method. Firstly, to identify the applicability of MDSA method, 4-inputs of vehicle HVAC system were the signals measured by accelerometers attached on the selected noise sources which were composed of blower, evaporator, heater and duct. While 1-output which was driver's position sound was the SPL signals measured by a remote microphone, when the blower motor was operating. We identify efficiency of systems modeled with four Inputs/single output through ordinary coherence function (OCF) and partial coherence function (PCF). As a result of experiment, the blower accounted for $62-88\%$ of the overall level of sound energy density. Also, according to the analysis of acoustic signal and vibration signals measurement, an investigation of the noise source identification in the vehicle HVAC is presented. With the sound intensity method, the major sources of the vehicle HVAC radiation are verified. Also the method of improving the noise reduction is proposed by attaching damping patch access to blower motor and noise reduction is verified.
Keywords
Multi-dimensional spectrum analysis; HVAC; Partial coherence function; Multiple coherence function; Coherent-analysis;
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