What Is a Cooling Fan?
A cooling fan is a device in which an AC motor or DC motor with blades attached is installed in a casing to cool an object by the airflow generated by the rotation of the motor.
There are three main types of blades: propeller type, cylindrical type with blades arranged in a circumferential shape, and long cylindrical type with blades arranged in the same way. The propeller type is the most popular type of cooling fan because it generates air in the axial direction of the motor, which allows for a large airflow and a compact structure.
Uses of Cooling Fans
In recent years, the demand for cooling fans has been increasing due to the higher functionality and speed of various office automation equipment, especially personal computers, and the heat generated by the equipment.
Various sizes of cooling fans are available to meet different cooling designs. For example, those that are attached to equipment housings to cool the entire equipment interior, and those that are attached near heat-generating components such as circuit boards and CPUs to blow air directly to them for more efficient cooling.
For cooling outdoor equipment and machine tools, waterproof and oil proof measures are also available.
Principle of Cooling Fans
A propeller-type cooling fan consists of a motor with blades attached to a hollow casing, and through holes in the four corners of the casing, for attaching the fan to the equipment to be cooled. The structure of the cooling fan itself is quite simple, but due to the nature of its task of cooling during equipment operation, it is a continuous operation device that requires more durability than the equipment to be cooled.
The blades, which rotate under the driving force of the motor, are constantly subjected to a reaction force equivalent to the airflow generated in the direction perpendicular to the motor shaft. Furthermore, this load is a moment load that is greatest at the tip of the motor shaft and least at the base of the motor, depending on the width of the blades. In addition, one end of the motor shaft is unsupported and cantilevered. To maintain durability beyond that of the device to be cooled under these conditions, each manufacturer guarantees the catalog life of the cooling fan. This is done by selecting a bearing structure (ball bearing) inside the motor and a long-life lubricant sealed in it, both of which have been carefully considered for durability.