Home use "220V Cooling Fan" are three blades, blade airfoil shape is a bird (design terminology), this form of blade flow, low noise, in line with principles of fluid mechanics, it made use of fans for home use. So the vast majority of fans are three leaves. In addition, "220V Cooling Fan" three leaves have a better balancing, easy to produce oscillation, thereby reducing bearing wear. Prolong life, reduce maintenance costs. For the mechanical point of view: 3 "220V Cooling Fan" and form a reasonable mechanical power asymmetry, when the blade does not have a power potential, the other two in a state of potential energy, potential energy blade 2 can easily drive the natural one does not have the potential to temporarily blades can save electricity and conserve energy.