Noise reduction of fan motors considering supporting structure for the fan

It is important for many home appliances to reduce their noise. Many motors are used in these appliances and their electromagnetic exciting force or vibration sometimes cause noise. When the electromagnetic exciting force and the mechanical system resonate, vibration and noise level rise. In this paper, we investigate the noise of the exhaust fan and try to reduce it. In order to clarify the source of the noise, we analyzed the frequency characteristics of the sound and the electromagnetic exciting force. We also examined the mechanical system such as natural frequency and vibrational mode of the exhaust fan. From these examination results, we recognized that the source of the noise was the resonance with the radial force and the mechanical system of the fan. Then we modified the shape of supporting structure slightly and reduce the vibration level of the fan. As a result, we achieved 10 dB of noise reduction. © 2013 The Japan Society of Mechanical Engineers.