小型機器に搭載された冷却ファンの騒音特性

抄録

Recently the noise reduction of a small fan for cooling electronic devices is required. In small electronic devices, noise increases due to obstacles such as a heatsink and a louver, and the narrow flow path structure. In this paper, noise characteristics in a narrow flow path were investigated thorough noise measurements using a simulated device that reproduced the flow path of an electronic device. First, the noise without heatsink model was measured. Second, the noise with heatsink models was measured. Then, noise characteristics were also investigated at different heatsink position and number of fins. The fan operated at two speeds, 40r/sec and 60r/sec in all experiments. As a result, it is found out that peaks appear at constant frequency regardless of the setting position of heatsink model, the number of fins, and the rotational speed of the fan. Furthermore, it is revealed that the peak frequency is close to the resonance frequency of an acoustic tube.