US20120321457A1 - Cooling fan with tapered hub - Google Patents

Abstract

A cooling fan includes a fan housing and a rotor received in the fan housing. The fan housing has an air inlet and an outlet opposite to the air inlet. The rotor includes a shaft, a hub engaged with the shaft, and a plurality of rotary blades extending outwardly from the hub. The hub has an outer surface expanding along a direction parallel to a central axis of the shaft from the air inlet to the air outlet.

Description

BACKGROUND
• 1. Technical Field
• The present disclosure relates generally to cooling fans, and more particularly to an axial fan with a large airflow.
• 2. Description of Related Art
• Cooling fans are commonly used in combination with heat sinks for cooling electronic components, such as CPUs. Normally, the heat sink is arranged on the electronic component to absorb heat therefrom, while the cooling fan is arranged on the heat sink to produce forced airflow flowing through the heat sink to take away the heat.
• Generally, the cooling fan includes a hub and a plurality of blades extending from the hub. The hub is usually cylindrical and blocks airflow in an air inlet of the cooling fan. As a result, an air-volume and an air-pressure of the airflow in the air inlet will reduce.
• What is needed is a cooling fan which can overcome the limitations described.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is an isometric view of a cooling fan in accordance to an embodiment of the present disclosure.
• FIG. 2 is a cross-sectional view of the cooling fan ofFIG. 1.
DETAILED DESCRIPTION
• Embodiments of the disclosure will now be described in detail with reference to the accompanying drawings.
• Referring toFIG. 1, acooling fan100 includes afan housing10 and arotor20 received in thehosing10. Thefan housing10 has a cubical configuration and includes atop plate11, abottom plate13, and alateral wall15 interconnecting thetop plate11 and thebottom plate13. Each of thetop plate11 and thebottom plate13 has a rectangular shape similar to each other. Thetop plate11 defines acircular air inlet110.
• Thebottom plate13 defines acircular air outlet130 corresponding to theair inlet110 of thetop plate11.
• Referring toFIG. 2, thebottom plate13 includes a supportingplate16 at theair outlet130. The supportingplate16 is connected to thebottom plate13 by a plurality of ribs (not shown). Acentral tube17 extends from the supportingplate16. Thecentral tube17 receives abearing30 therein. Thelateral wall15 is annular and has aninner surface150 surrounding areceiving room18.
• Therotor20 includes ahub21 and a plurality ofrotary blades23 connecting a circumference of thehub21. Thehub21 includes acircular top wall210 and anannular wall212 extending downwards from thetop wall210. Thetop wall210 and theannular wall212 cooperatively define aspace215 in thehub21. Thetop wall210 is flat and faces theair inlet110. Therotor20 includes ashaft214 mounted with thehub21. A top end of theshaft214 is fixedly engaged in a central portion of thetop wall210 of thehub21. Theshaft214 is assembled in thebearing30 and rotatably mounted on the supportingplate16. Theinner surface150 of thelateral wall15 is parallel to a central axis O of theshaft214.
• Theannular wall212 of thehub21 has anouter surface218. Theouter surface218 converges (tapers) in an upward direction, i.e., theouter surface218 ofannular wall212 slants towards the central axis O of theshaft214 from theair outlet130 of thebottom plate13 to theair inlet110 of thetop plate11. Put another way, a distance between theouter surface218 of thehub21 and theshaft214 expands gradually in the downward direction along theair inlet110 of thetop plate11 to theair outlet130 of thebottom plate13. Accordingly, theair inlet110 of thetop plate11 is larger than theair outlet130 of thebottom plate13. Theannular wall212 of thehub21 has an inner surface facing theshaft214, the inner surface defines a cylinder having a constant diameter. Thehub21 receives amagnet25 attached on the inner surface of theannular wall212. Astator50 surrounds thecentral tube17 in thespace215.
• During operation, therotor20 is rotated by the interaction of the alternating magnetic field established by thestator50 and the magnetic field of themagnet25. Therotary blades23 thus produce forced airflow to take away heat generated in an application environment that employs thecooling fan100. Since theouter surface218 of thehub21 tapers upwards to make theair inlet110 of thetop plate11 larger than theair outlet130 of thebottom plate13, during rotation of therotor20, a block of thehub21 for the forced airflow reduces, and thecooling fan100 can produce larger air-volume and air-pressure in theinlet110. Thus coolingfan100 can operate smoothly and quietly, and the quality of thecooling fan100 obtained should be good. In this embodiment, thecooling fan10 can increase 5% air-volume and 48% air-pressure than a conventional fan without variable outer wall of a hub.
• It is to be understood, however, that even though numerous characteristics and advantages of certain embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims (12)

1. A cooling fan comprising:

a fan housing having an air inlet and an outlet opposite to the air inlet;

a rotor received in the fan housing, the rotor comprising a shaft, a hub engaged with the shaft, and a plurality of rotary blades extending outwardly from the hub, the hub having an outer surface expanding outwards along a direction parallel to a central axis of the shaft from the air inlet to the air outlet.

2. The cooling fan ofclaim 1, wherein a distance between the outer surface of the hub and the shaft gradually increases from the air inlet to the air outlet.

3. The cooling fan ofclaim 1, wherein the fan housing has a lateral wall with an inner surface facing the hub, the inner surface being parallel to the central axis of the shaft.

4. The cooling fan ofclaim 1, wherein the hub comprises a circular top wall and an annular wall extending from the top wall towards the air outlet, an outer surface of the circular top wall of the hub facing the air inlet being flat, an outer surface of the annular wall of the hub expanding from the air inlet to the air outlet.

5. The cooling fan ofclaim 4, wherein the annular wall of the hub has an inner surface facing the shaft, the inner surface defining a cylinder having a constant diameter.

6. The cooling fan ofclaim 5, wherein the hub receives a stator therein, and a magnet is attached on the inner surface of the annular wall and surrounding the stator.

7. A cooling fan comprising:

a fan housing having an air inlet and an outlet opposite to the air inlet;

a rotor received in the fan housing, the rotor comprising a shaft, a hub engaged with the shaft, and a plurality of rotary blades extending outwardly from the hub, the hub having an outer surface tapered from the air outlet to the air inlet.

8. The cooling fan ofclaim 7, wherein a distance between the outer surface of the hub and the shaft gradually increases from the air inlet to the air outlet.

9. The cooling fan ofclaim 7, wherein the fan housing has a lateral wall with an inner surface confronting the hub, the inner surface being parallel to a central axis of the shaft.

10. The cooling fan ofclaim 7, wherein the hub comprises a circular top wall and an annular wall extending from the top wall towards the air outlet, an outer surface of the circular top wall of the hub facing the air inlet being flat, an outer surface of the annular wall of the hub expanding from the air inlet to the air outlet.

11. The cooling fan ofclaim 10, wherein the annular wall of the hub has an inner surface facing the shaft, and the inner surface has a constant diameter.

12. The cooling fan ofclaim 11, wherein the hub receives a stator therein, and a magnet is attached on the inner surface of the annular wall and surrounding the stator.

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