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신재우(Jaewoo Shin),원종식(Jongsik Won),김증한(Jeunghan Kim) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
PBNR(Power Based Noise Reduction) is a useful tool to predict the vehicle interior noise. It can measure noise reduction quantity from engine room to cabin using acoustic transfer function. This method provide acoustic package performance of the vehicle and able to prepare frequency band to same segment or benchmarking vehicle. This paper studies reciprocity that is based on PBNR test. And it also shows that noise reduction quantity is almost same when tonal noise is generated from vehicle. It can be used to predict motor or fan noise of electronic vehicle.
정인중(Injoong Joung),신재우(Jaewoo Shin),김성영(Sungyoung Kim) 한국자동차공학회 2018 한국자동차공학회 학술대회 및 전시회 Vol.2018 No.11
In the early stage of vehicle development, initial acoustic package proposed base on the ideal package condition by considering the noise source characteristics and experience of the previous vehicle, database and benchmarking results. However, in the development process of the vehicle, the package space and the part matching condition and the noise characteristics of the source are changing. So, the actual NVH performance is lower than the initial prediction performance, and need to tuning package in vehicle condition. The most difficulty of acoustic package development is to identify the invisible noise path and weak point in a small closed environment and apply countermeasures thereto. In such case, finding a solution with CAE(SEA) is not appropriate. Therefore, vehicle test needed and methods are based on trial and error method at the chassis dynamo and/or test track. This study suggests an intuitive and easy way for acoustic package test in the hemi-anechoic chamber without chassis dynamo. The beamforming acoustic camera can be used to detect the weak point and instantly show the performance changes. The target was the interior noise improvement for the engine combustion noise. So, the test environment was the hemi-anechoic chamber with a single point source inside of the engine room and an acoustic camera placed in the vehicle interior. For the overall airborne noise performance PBNR was also validated in the lab-test condition. The final evaluation of countermeasure was completed by driving test with the applicable countermeasure concept and final results will be reflected in the design.