定速旋转式压缩机拍频声分析与改善

Analysis and improvement of the beat frequency noise in constant speed rotary compressor

某定速旋转式压缩机搭载的分体式空调,系统外机运行时存在明显嗡嗡声,严重影响空调外机声品质。通过对空调外机噪声信号实时采集,并采用带阻滤波器分析,确认影响听感的嗡嗡声是174 Hz和178 Hz两个相近频率产生的拍频噪声。分析得出拍频噪声的激励源为压缩机的三倍转频与异步电机的两倍转差频率调制产生的拍频振动,经过系统排气管道的共振放大后导致了钣金振动从而引起拍频噪声。最后对系统排气管道进行约束模态仿真分析及优化,消除了嗡嗡声,提升了该空调系统外机的声品质。

There is an obvious buzz in the outdoor unit for a running air conditioning system with a fixed speed compressor,which seriously affects the sound quality of air conditioner.The noise signals of air conditioner are collected and further analyzed by a band-stop filter.It is found that the buzzing noises are beat frequency signals induced by the modulation of two similar frequencies of 174 Hz and 178 Hz.Accordingly,the excitation source has two kinds of vibrations with two different frequencies.The first frequency corresponds to the three-fold rotational frequency of the compressor,while the second one is the two-way slip frequency of the asynchronous motor.As such,the vibrations of sheet metal are amplified by the resonance of the exhaust pipe,leading to abnormal noises.Finally,the structure of the exhaust pipe is optimized by establishing constrained simulation model.The results show that the buzzing noises are eliminated,and the sound quality of the air conditioner is greatly improved.