Analysis and Control of Hermetic Compressor Sound Power Levels

The consumer market is demanding that the noise level of appliances be reduced to lower and lower levels to satisfy new expectations for environmental quality. This has placed a burden on the manufacturers of compressors for air conditioners and heat pumps to reduce noise radiated by their units. In order to accomplish this task, the approach has been to apply advanced signature analysis and structural dynamic analysis techniques to the compressors to learn the manner in which the excitation is produced and transmitted, and how the noise is radiated by the structure. Lastly, as a result of information gained through analysis of the system and its response, design changes are implemented in the compressor which significantly reduce the noise radiated by it. An example is given where hardware changes were made to an existing hermetic compressor in order to reduce its noise level. These changes consisted of reducing the transmissibility between the internal compressor components and the shell, and reducing the response of the shell through damping. Results are given which demonstrate the amount of noise reduction attainable with this approach.