Loudness reduction of household refrigerator by structural modification

In this study, loudness reduction of a household refrigerator was attempted by the structure modification. At first, loudness of the radiated noise was analyzed at various operational condition and the loudness was observed to be increased at a specific compressor rotational speed and the large sound pressure level (SPL) at 100 Hz was the main factor. Through the vibration analysis of the refrigerator body, the SPL was found to be increased largely by the resonance between the compressor rotational order input force and the natural frequency of the refrigerator body. Then, for the reduction of the sound, the rubber bush hardness of the compressor mount was softened and the loudness was decreased. However, the door vibration at low rotational speed was increased. Accordingly, we attempted to modify the body structure for the loudness reduction to compatible with small door vibration. Vibration mode analysis indicated that the high contributing vibration behavior of the body increasing the loudness and a countermeasure was applied to constrain the behavior. Finally, the loudness was decreased about 30% and the vibration was not increased at the low rotational speed by the countermeasure.