When an automobile idles, the engine speed should be decreased to reduce energy consumption and noise. The pulley ratio between the alternator and engine is increased to attain higher alternator speeds and to generate sufficient power for electronic equipment. However, at high engine speeds, an increased pulley ratio results in faster alternator rotation. The sound quality of alternators used in automobiles is discussed. It is known that a rapid change of rotation sometimes results in an unpleasant or unnatural noise from the cooling fans affixed to the rotors of the alternator. This noise is often referred to by the imitated or onomatopoeic expression of ''myah'' in Japanese. It is found that the primary cause of this ''myah'' sound is the frequency change of the maximum 1/3 octave band noise level, and that sound quality can be improved by controlling this frequency within a specific range.
Sound quality evaluation method of automobile alternators
Bewertungsmethode für die Schallqualität von Kfz-Drehstromlichtmaschinen
2001
4 Seiten, 3 Bilder, 1 Quelle
Conference paper
English
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