The fan is mainly composed of four parts: blades, guard (net cover), fan head, and base. The fan head includes the electric motor, front and rear end covers, and the oscillation mechanism, which together serve as the main power source and driving components of the electric fan.
(1) Blades:
The blades are the main components that generate airflow. The design quality of the blades directly affects the fan's power consumption, air volume, air pressure, and noise performance. The shape and size of the blades are typically determined through repeated testing, evaluation, and analysis to achieve the optimal design. Most pedestal fans use three-blade designs shaped like palm leaves or broadswords, while some models use four blades.
(2) Guard (Net Cover):
The guard prevents accidental contact with the blades, reducing the risk of injury. In addition to sufficient mechanical strength, it should also feature an attractive and modern design.
(3) Fan Head:
The fan head consists of the electric motor and the oscillation mechanism.
(4) Motor:
The fan motor is typically a single-phase small asynchronous motor. It mainly consists of front and rear covers, a stator assembly, and a rotor assembly. The stator includes the stator core and windings, while the rotor includes the rotor core, windings, and shaft.
The motor speed is determined by the number of poles: fewer poles result in higher speed, which can produce greater airflow. However, higher speed also increases noise and raises the blade's peripheral (tip) speed. Excessive tip speed may pose safety risks. Therefore, to ensure safety and reduce noise, standards specify the maximum allowable blade tip speed for electric fans.
(5) Oscillation Mechanism:
The fan head is driven by the motor and can oscillate within a specified angle. According to standards, for fans with blade diameters below 250 mm (10 in), the oscillation angle should not be less than 60°, while for those above 300 mm (12 in), it should not be less than 80°.
The oscillation mechanism consists of a reduction (gear) mechanism, a four-link mechanism, and a control mechanism. After passing through a two-stage reduction system, the motor speed is reduced to about 47 r/min at the oscillation gear. This motion is then transmitted through the four-link mechanism to achieve the side-to-side oscillation of the fan head.
