What is the difference between an external rotor axial fan and an internal rotor fan

　　We know that there are many types of fans, of which the external rotor axial flow fan is the main one. Generally, there are two types of fans, one is an external rotor fan and the other is an internal rotor fan. So what is the difference between an external rotor axial fan and an internal rotor fan? Let’s take a look.

　　The difference between external rotor fan and internal rotor fan:

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

　　Internal rotor fan is an assembly spindle or motor composed of iron core and coil. After power on, AC internal rotor fan generates a magnetic field through the starting copper block in the motor to work; DC fan uses Hall IC to drive the fan to generate a magnetic field and rotate. Generally, DC fans have an inner rotor structure, AC fans are mostly inner rotor blades, and outer rotor blades are basically metal iron blades.

　　The advantages of AC inner rotor fan blade are that the blade is light, the motor is easy to produce and assemble, and the cost is low. The rotor fan blade fan in DC generally has a high speed and is easy to be protected. And the air volume of the rotor fan in the AC can be much larger, and it can be made into energy-saving control products. The disadvantage is that the AC inner rotor fan is easy to damage the motor due to unstable voltage and has a short service life. In addition, the motor temperature rises, the speed is low, and the power consumption is large.

　　AC outer rotor fan blades are basically connected with spindles and fan blades (iron blades or plastic blades). The motor can be made into a fully enclosed honeycomb structure, and it can run quickly by starting the capacitor. Its advantage is: AC fans of major international brands have more external rotor structures. Because of its low power consumption, high speed, and work efficiency much higher than that of the inner rotor. The metal fan blade has large inertia and the fan is resistant to high and low temperature environments. The motor can be directly dust-proof and moisture-proof, and can even be made into an IP56 protection level. It is not easy to damage and has a long service life. The disadvantage is that the cost is higher than the internal rotor fan.

　　The characteristic of 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 rate. The air flow conforms to the phase law. Under the same pressure and constant flow rate, the flow changes linearly with the increase of the width of the impeller. Usually it needs to be equipped with a rotating chamber (volute). The rotating chamber is generally made of aluminum, galvanized sheet or plastic.

　　Through the introduction of "the difference between external rotor fans and internal rotor fans" above, we know that there are actually many differences between external rotor axial fans and internal rotor fans. Because there are so many differences between the external rotor axial fan and the internal rotor fan, these two types of fans will focus on different areas. But these two kinds of fans are very important to us, we must understand.Related reading: more Fans products