1. Field of the Disclosure
The disclosure relates to an axial fan, and more particularly to an axial fan providing increased airflow and reduced operating noise.
2. Description of Related Art
With continuing developments in technology, electronic packages such as CPUs (central processing units) generating more heat that requires immediate dissipation. Axial fans are commonly used in combination with heat sinks for cooling CPUs.
Often, an axial fan includes a stator and a rotor. The rotor includes a hub and a plurality of fan blades extending outwardly therefrom. A permanent magnet is arranged in the hub and surrounds the stator. The stator includes a stator core with coils wound therearound. When electrical current is supplied to the coils, the fan blades, rotated by magnetic force of the coils, produce forced airflow. A fan housing surrounding the stator and the rotor guides the forced airflow from one side to an opposite side. However, during operation, while the fan blades rotate, the housing is stationary, and a gap is defined between the outer ends of the blades and the housing to avoid friction therebetween. Accordingly, size of the fan blades is limited, which correspondingly limits airflow. In addition, airflow from the rotary fan blades impacts the stationary fan housing, increasing noise of the axial fan.
For the foregoing reasons, there is a need in the art for an axial fan which overcomes the described limitations.
According to an exemplary embodiment of the disclosure, an axial fan defines an air inlet on one side and an air outlet on an opposite side along an axis of the fan. The axial fan includes a base, a bearing, a stator and a rotor. A central tube extends upwardly from the base, around which the stator is mounted. The bearing is received in the central tube of the base and the rotor is rotatably supported by the bearing. The rotor includes a hub, a plurality of rotary blades extending outwardly from the hub, and an annular wall surrounding the rotary blades. The annular wall connects to outer ends of the rotary blades and rotates therewith, guiding airflow from the air inlet to the air outlet during operation of the fan.
Other advantages and novel features of the disclosure will be drawn from the following detailed description of the exemplary embodiments of the disclosure with attached drawings.
Referring to
The stator 20 is mounted around the central tube 12. The stator 20 includes a stator core 22 with coils 24 wound thereon to establish an alternating magnetic field, and a PCB 26 (printed circuit board) with electronic components mounted thereon. The electronic components are electrically connected with the coils 24 to control electrical current flowing through the coils 24. To prevent the coils 24 from making electrical contact with the stator core 22, a pair of insulating frames 28 cover the stator core 22.
Referring to
After assembly, the stator 20 is fixed to the central tube 12. The shaft 33 of the rotor 30 extends into the bearing 100 and thus is rotatably supported thereby. The hub 32 of the rotor 30 surrounds the stator 20 with the magnet 34 confronting the coils 24 of the stator 20. The annular wall 38 of the rotor 30 is located among the four fixed portions 16. An outer surface of the annular wall 38 is spaced from the fixing portions 16, and the bottom side 382 of the annular wall 38 is higher than the base 10.
During operation, the rotor 30 is rotated by the interaction of the alternating magnetic field established by the stator 20 and the magnetic field of the magnet 34 of the rotor 30. The rotary blades 36 thus produce forced airflow. The annular wall 38 surrounding the rotary blades 36 guides the forced airflow from the air inlet 15 to the air outlet 17. Furthermore, the annular wall 38 is connected to the outer ends 364 of the rotary blades 36 and rotates with the rotary blades 36, increasing a sturdiness of the axial fan, such that operating noise of the axial fan is reduced. In addition, as the rotary blades 36 extend from the hub 32 to the annular wall 38, length of the rotary blade 36 along the extending direction increases, increasing airflow generated by the axial fan and correspondingly providing improved heat dissipation.
It is understood that the invention may be embodied in other forms without departing from the spirit thereof. Thus, the present examples and embodiments are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.
Number | Date | Country | Kind |
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2008 1 0068325 | Jul 2008 | CN | national |
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2528992 | Jan 2003 | CN |
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Number | Date | Country | |
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20100003131 A1 | Jan 2010 | US |