Abstract: The metal shell of the variable frequency outdoor unit is the main noise radiation source of the outdoor unit at certain frequencies under the excitation of the compressor. Using a half power band method, the damping of the original sheet metal structure and the sheet metal structure with added damping layer was compared. The damping was increased from 0.43% to 2.60%, and the sheet metal structure with added damping layer was applied to the outdoor unit casing. The peak noise was reduced by 12.8 dB(A), significantly improving the noise quality of the outdoor unit.

Key words: Air-conditioner, Damping, Structure radiation noise