Rotational motor plus cam to produce the sinusoidal motion.
Rotational motor plus cam to produce the sinusoidal motion.
It is tempting to use a traditional electric motor such as a BLDC connected to a cam in order to produce the required sinusoidal motion of the fan blade. The advantage of this is that one does not need to design a custom linear motor. A disadvantage of this approach is the higher than 20Hz noise introduced into the system by the motor cogging and motor commutation. The fans and support structure have very little damping, so small motor sounds will be amplified by the fan blades, which will increase the noise level.