However, in terms of physical composition, DC fans have the same basic structure as AC fans: fan blades, rotor, stator, fan frame and bearing system.
Composition of DC and AC fans1---- fan blades
Blade inclination: the greater the inclination, the greater the pressure difference between the upper and lower surfaces of the blades, and the greater the wind pressure at the same speed.
Number of blades: Most DC and AC fans have an odd number of blades such as 7, 9, 11 etc. If an even number of fan blades are used, it is easy for the system to resonate and will cause the blades or shaft to fracture.
Blade curvature: slightly curved in the direction of rotation, a certain curvature, can ensure that the airflow is concentrated in the columnar space directly in front of the air outlet, increasing the air distance and wind pressure.
Spindle diameter: Due to the presence of the motor and bearings, there is inevitably a blind spot in the centre of the DC and AC fan spindles where no airflow passes.
Fan balance: When the physical centre of mass of the fan blades of DC and AC fans is not on the same axis, the fan blades will cause an imbalance in operation, i.e. vibration.
Components of DC and AC fans2 ---- rotor
Includes the fan blade, the shaft, the magnetic ring, the outer frame of the magnetic ring and the oil ring.
Components of DC and AC fans3---- stator
Includes motor, outer frame, bearings and grommets.
Components of DC and AC fans4---- fan frame
The fan frame "restrains" the air flow driven by the fan blades, controlling its direction of flow, suppressing back-excursion and scattering, and concentrating it in the desired direction of air supply. The materials and construction used need to be strong enough to withstand physical impact to a certain extent, protecting the fan blades, motor and other delicate components.
Components of DC and AC fans5 ---- Bearing systems
Bearings act as a bottleneck factor in the life of DC and AC fans, and also have a significant impact on the operating noise and manufacturing costs of the fan. Bearing systems for DC and AC fans can be divided into: ball bearings (also divided into single and double ball bearings), oiled bearings, ceramic bearings, hydraulic rifling bearings ......
