Abstract: Noise is an important sensory indicator of refrigerator products and also a key concern for consumers. If the refrigerator has high noise or abnormal noise, it may cause consumer complaints. The evaluate of the noise during the pull down stage of a frost-free side-by-side refrigerator by monitoring and recording the noise test process throughout the entire period, combined with methods such as ear sensing and near-field microphone fixed-point monitoring. It is found that the refrigerator has problems such as high compressor noise, obvious resonance of connecting pipes, and abnormal noise during the damper opening stage during the pull down stage. Through the implementation of the compressor step-up speed control, the connection pipe wrapped with soft XPE foam, and the gap between the damper and the air duct foam increased, the peak noise of the pull down stage was reduced from 45 dB(A) to 37 dB(A), and a series of problems such as the resonance noise of the connection pipe and the abnormal noise of the damper opening were eliminated. The noise in the pull down stage of the whole machine has been significantly improved, and the user's experience has been greatly improved.

Key words: Pull down stage, Resonance, Abnormal noise, Step-up speed control, Vibration-isolating material