What Is The Difference Between An Outer Rotor Axial Fan And An Inner Rotor Fan?

We all know that there are many types of fans, among which the outer rotor axial fan is the main type. Everyone knows that there are two types of fans, one is the outer rotor fan and the other is the inner rotor fan. So what is the difference between the outer rotor axial flow fan and the inner rotor fan? Let’s find out below.
What is the difference between an external rotor fan and an internal rotor fan?

The outer rotor fan adopts the advanced structure and reasonable aerodynamic design of the outer rotor motor to directly drive the impeller, and has the characteristics of high efficiency, low noise, light weight, compact structure, and convenient installation and maintenance.

The inner rotor fan is a spindle or motor composed of an iron core and a coil. After the power is turned on, the AC inner rotor fan works through the starting copper block in the motor to generate a magnetic field; the DC fan drives the fan through the Hall IC to generate a magnetic field and rotate. Generally, DC fans are of inner rotor structure, most of AC fans are also inner rotor blades, and outer rotor blades are basically of metal iron blade structure.

The advantage of the AC inner rotor blade fan is that the blade is light, the motor is easy to produce and assemble, and the cost is low. The DC inner rotor blade fan generally has a higher speed and is easy to do protective treatment. And the air volume can be much larger than that of the AC inner rotor fan, and it can be made into an energy-saving control product. The disadvantage is: the AC inner rotor fan is easy to damage the motor due to voltage instability, and the service life is short. Moreover, the temperature of the motor rises, the speed is low, and the power consumption is large.

The blades of the AC outer rotor are basically connected by the spindle and the blades (iron blades or plastic blades). The motor can be made into a fully enclosed honeycomb structure, which can run quickly through the starting capacitor. Its advantages are: AC fans of major international brands are mostly made of external rotor structure. Because of its low power consumption, high speed, and work efficiency is much higher than that of the inner rotor. The metal fan blades have high inertia, and the fan is resistant to high and low temperature environments. The motor can be directly protected against dust and moisture, and can even be made into an IP56 protection level. Not easy to damage and long service life. The disadvantage is that the cost is higher than that of the inner rotor fan.

The characteristic of the centrifugal fan is that the pressure rises quickly, which mainly depends on the width of the impeller, the air performance and the appropriate large flow. The air flow conforms to the phase law. Under the condition of the same pressure and constant flow velocity, the flow changes linearly with the increase of the width of the impeller. Usually it needs to be equipped with a rotating chamber (volute), which is generally made of aluminum, galvanized sheet or plastic.
To sum up, there are actually many differences between the outer rotor axial fan and the inner rotor fan. Because there are so many differences between the outer rotor axial flow fan and the inner rotor fan, these two kinds of fans will focus on different fields. But these two kinds of fans are very important to us, we must understand them.