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

Jun 10, 2020

What is the difference between an outer rotor fan and an inner rotor fan?


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


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


The advantages of AC inner rotor fan blades are that the fan blades are light, the motor is easy to produce and assemble, and the cost is low. DC inner rotor fan blades generally have higher rotation speeds and are easy to be protected. And the air volume of the AC inner rotor fan can be made much larger, and can be made into an energy-saving control product. Disadvantages are: AC inner rotor fan is easy to damage the motor due to unstable voltage and has a short service life. And 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 or plastic leaves). The motor can be made into a fully enclosed honeycomb structure, which can be quickly operated by starting the capacitor. The advantage is that the AC fans of major international brands all have more external rotor structures. Because of its low power consumption, high speed, and working efficiency is much higher than 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 protected against dust and moisture, and can even be made to 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 centrifugal fans 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 conditions of the same pressure and constant flow rate, the flow rate changes linearly with the increase of the impeller width. Usually need to be equipped with a rotating chamber (volute), the rotating chamber is generally made of aluminum, galvanized sheet or plastic.