Research On Vibration And Noise Of Compressor

Compressor is the main noise resource of refrigerator. As the development of economy and improvement of living condition, people put more emphasis on noise control. The reduction of refrigerator noise has great meanings for protecting work and living environment.Crankshaft connecting-rod piston mechanism's unbalance movement is important cause for the generation of compressor's vibration and mechanical noise. The research related to reciprocation compressor's shell vibration and noise radiation used to focus on shell parameters design, pump connecting means and existing oil's influence for shell's modal frequencies, or employing kinetics theoretical formula to improve structure parameters for movement mechanism. FEM/BEM simulation technologies upon compressor's vibration and shell acoustic radiation research were not very much reported. As for the shell vibration response under mechanical stimulation, FEM has only been employed upon double rotor compressor research. Simulation for reciprocation compressor's shell vibration and acoustic radiation has not been reported.Combined with the project of compressor's vibration and noise characteristic research in Embraco, this thesis is base on the theoretical analysis and the former experience. Besides that, the thesis is focused on the research of reciprocation compressor's vibration and noise by the means of computation simulation and experimental analysis. This thesis is composed of 4 main parts:Firstly, on the basis of compressor's noise resource and transmission path analysis, this thesis measures vibration and noise before and after removing air-action components of compressor, gaining frequency spectrum of vibration/noise and sound power level. By comparing measurements of two conditions, the noise resource for main noise peak and vibration transmission path has identified.Secondly, this thesis employs acoustic software to do FEM-Fluid analysis for suction muffler, gaining transmission lost for R600a. Through acoustic modal analysis, some muffling gorges are explained to have stimulated acoustic co-vibration inside muffler. R134a and R600a's transmission lost curves have been compared as well.Thirdly, this thesis makes FEM structure harmonic analysis for compressor's vibration caused by crankshaft connecting-rod piston mechanism unbalance movement. Compressor pump and shell surface's vibration velocity distribution are gained. Unbalance moment caused by gas force has great influence for pump vibration, especially for the torsion vibration in horizontal plane. Importing analysis results of vibration response into BEM software for sound radiation simulation, the radiation mainly exists on the starter side and its opposite side.At last, tests of pump/shell vibration and sound power are designed and carried out after removing air-action. By comparing measurements and simulation results, crankshaft connecting-rod piston mechanism is verified as main stimulation resource for low-frequency vibration. Exaction of vibration response analysis can meet project exploit requirement. Noise radiation simulation and measurement results give some refer to compressor's mechanical noise prediction.