An inner rotor fan is an electric motor which drives a set of fan blades to generate a flow of air or gas. In contrast to an external rotor axial fan, the rotor of an internal rotor fan is mounted inside the stator, and the fan blades are attached to the rotor. This topology allows the motor to be built much smaller, and also allows it to operate at higher speeds and with greater power density.
In general, fans are used in electronic devices to dissipate heat from components such as chips. A conventional plastic fan rotor is formed by an injection molding process, with multiple blades being formed radially on the rotor. Because the size of electronic devices becomes more compact, the blades of the plastic fan rotor are made thinner and thinner. However, the thinned blades become weak and fragile, easily snapping when the fan rotor is rotated at high speed.
To resolve this problem, an inner rotor fan is designed with more than one set of blades to increase the number of rotations. In addition, the metal fan rotor is coated with a protective film to protect the rotor from dust and moisture.
The present invention provides a fan rotor assembly with an inner rotor and an outer rotor, a central retainer and a central shaft. The inner rotor has multiple first blades, and the outer rotor is stacked on the inner rotor and has multiple second blades. The central shaft is mounted in the central retainer under the inner rotor.
A positioning cylinder is positioned between the inner and outer rotors, and has a top board (51) and a sidewall (52). The top board abuts the first connecting tabs (23) of the inner rotor and the second connecting tabs (13) of the outer rotor. The sidewall prevents relative lateral movements between the inner and outer rotors. The axial fan is equipped with a starting copper block to produce a magnetic field to start the fan. After energization, the fan operates through the Hall IC to generate the magnetic field and rotate.
Compared to an external rotor axial fan, an inner rotor fan is more compact and lightweight, making it easier to transport and handle. Furthermore, an internal rotor fan can operate at higher speeds and provide greater airflow than a conventional external rotor fan, making it suitable for use in a wide range of applications.
In addition, an inner rotor fan can be built with a variety of different blade angles and shapes to meet specific application requirements. For example, a fan with a more shallow angle can be used in places where space is limited, and a fan with a more narrow blade width can be used to achieve a high airflow at a lower pressure. An internal rotor axial fan can also be designed with various levels of noise reduction, energy efficiency and durability.
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