转子压缩机摩擦噪声机理探究

Study on the Generation Mechanism of Frictional Squeal of a Rotary Compressor

为了研究转子压缩机摩擦噪声的形成机理,基于摩擦耦合引起摩擦系统自激振动的理论,建立了全尺寸的转子式空调压缩机摩擦噪声的有限元模型,模型中的接触对有:曲轴与上下法兰接触形成主副轴承,曲轴偏心部与滚子接触形成轴颈轴承,曲轴下偏心部端面与下法兰接触形成止推轴承。定义各个接触对的接触属性为库伦摩擦。利用复特征值分析法研究了该系统在滑动摩擦时的摩擦噪声发生趋势。进行了压缩机摩擦噪声的试验测量,测量了压缩机的振动信号,提取了振动信号的频谱。运用谐波小波包变换方法,成功识别出碰磨故障。曲轴和法兰间发生碰磨,可能是压缩机摩擦噪声的来源。仿真结果表明在f=10021Hz时,系统发生不稳定振动也即出现摩擦噪声。测得的振动信号的主频为10000Hz,模型预测结果和试验实测结果的比较显示该有限元模型预测的摩擦噪声频率接近试验实测的摩擦噪声频率,验证了模型的正确性。对转子压缩机摩擦噪声的影响因素进行了进一步的分析。结果表明当法兰的弹性模量增大到143000MPa时,可有效抑制摩擦噪声。并且摩擦系数越大,越容易发生摩擦噪声。

The work aims to study the formation mechanism of squeal of a rotary compressor.According to the mode-coupling mechanism for squeal,a full-size finite element model of a rotary compressor was established.The main contact pairs in this model are:the crankshaft was pressed into contact with the upper flange to form the main bearing,and was pressed into contact with the lower flange to form the sub bearing.the roller surface to the eccentric part surface of the crankshaft to form a journal bearing,and the end surface of the lower eccentric part of the crankshaft to surface of the lower flange to form a thrust bearing.The complex eigenvalue extraction method was used to study the tendency of the squeal occurrence propensity of the rotary compressor during working.Tests on squeal of the rotary compressor were carried out.The squealing vibration of the rotary compressor was measured,and the power spectrum density analysis of the squealing vibration was performed.Using the harmonic wavelet packet transform method,the rubbing fault was successfully identified.The crankshaft rubbing against the flange may be the source of the frictional noise of the compressor.Numerical results showed that the unstable vibration frequency of the rotary compressor was f=10021 Hz,which was corresponding to the frequency of the rotary compressor squeal.Results showed that the squeal frequency measured was in a good agreement with one predicted by the finite element model.Finally,the factors affecting squeal of the rotary compressor was studied.Results showed that increasing the elastic modulus of the flange can suppress squeal of the rotary compressor.And the greater the friction coefficient,the more likely friction-induced noise will occur.