Decreasing Noise Pollution of the Automotive Compressor in Preheating Mode

The acoustic profile of electrical vehicles is one of the most important parameters for consumers, when they select a car to purchase, considering models with similar characteristics. Therefore, even minor acoustic pollution produced by one of the auxiliary car systems, may worsen the customer's impression and significantly impact their choice. As a result, car manufacturers pay considerable attention to noise characteristics of all vehicular systems and initiate many researches in this area. One of the emerging topics is compressor operation in preheating mode, where compressor oil is heated to decrease its viscosity while the compressor is not rotating. Therefore, even minor operational noises are perfectly recognized and worsen the acoustic profile. In order to decrease these noises, the proposed paper studies compressors, operating in preheating modes, evaluates irradiated acoustic noises and proposes several directions to improving acoustic profiles. Thereafter, all approaches are analyzed, evaluated and the best technique is selected for further work. The feature of this work is the usage of equal loudness contours (ELCs) and equal annoyance contours (EACs), which reflects the specifics of human ear to sense sounds of various frequencies.