Heat dissipation fan

Abstract

A heat dissipation fan includes a housing, a first rotor, a second rotor, a base and a plurality of static blades. The first rotor has a shaft and a plurality of rotor blades. The second rotor is coupled to the first rotor and has a plurality of rotor blades. The base is disposed in the housing for supporting the first and second rotors. The static blades are disposed between the housing and the base, wherein a rear portion of each static blade extends along an axial line of the heat dissipation fan for improving the working efficiency of the second rotor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1 is a sectional view of a conventional fan; and

FIG. 2 is a sectional view of a heat dissipation fan of a first embodiment of the invention;

FIGS. 3A-3C are top views of the first rotor, the static blades and the second rotor;

FIG. 4 is a schematic diagram of rotor blades of first rotor, static blades and rotor blades of second rotor;

FIG. 5 is an exploded view of a heat dissipation fan of a second embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.

FIG. 2 shows a first embodiment of a heat dissipation fan of the invention. The fan includes a housing 21, a base 22 disposed in the housing 21, a plurality of static blades 23 disposed between the base 22 and the housing 21, a first rotor 24, a driving device 25 (for example, a motor) disposed through the base 22 and supported thereby, a shaft 26, and a second rotor 27. The second rotor 27 is disposed on a rear end (lee side) of the first rotor 24. An end of the shaft 26 passes a top surface of a hub 271 of the second rotor 27 and is fixed thereon. The inner portion of the hub 271 of the second rotor 27 is cup-shpaed. The shaft 26 is fixed to the second rotor 27 by riveting, screwing, adhesion, or other equivalent means. The driving device 25 can drive the first rotor 24 and the second rotor 27 via the shaft 26 to rotate the first rotor 24 and the second rotor 27 at the same speed.

A plurality of heat dissipation holes 242 are formed on the top surface of the hub 241 of the first rotor 24. A plurality of heat dissipation holes 272 are formed on the top surface of the hub 271 of the second rotor 27. When the first rotor 24 and the second rotor 27 are rotated by the driving device 25, airflow through the heat dissipation holes 242 and the heat dissipation holes 272 (as shown by the dotted lines) dissipates heat generated by the driving device 25 to elongate the used life thereof. The first rotor 24 includes a plurality of rotor blades 243. The second rotor 27 includes a plurality of rotor blades 273. The rotor blades 243 of the first rotor 24 incline upward. A windward side of the housing 21 includes an expanding portion 211 to increase intake airflow.

In terms of hydrodynamics, the rotation of the rotor blades will generate a pressure difference so as to generate airflow. However, when the air flow is discharged from the fan, it has an angle speed at the flow direction, thereby resulting in energy loss and decreasing heat dissipation efficiency. Further, in terms of flow field analysis, it will cause energy loss due to the generation of eddy on the heat dissipation fan. Moreover, when the airflow pass through the surface of rigid body, a shearing force is generated by friction, thereby causing energy loss. The gap between the tip of the rotor blades and the inner wall of the housing will also cause energy exhaust. The invention utilizes the Taguchi Method to obtain the optimum height ratio between the rotor and static blades. The static blades 23 guide airflow to reduce eddies, modify the angle speed to axial work, and improve the heat dissipation efficiency of the fan. When a ratio of a height h2 of the rotor blades 243 to a height h1 of the static blades 23 ranges from 1:1.6 to 1:2.2, the heat dissipation fan has the best efficiency and usage rate of space. The efficiency of the heat dissipation fan of the invention can be enhanced up to 45%. Eliminating the efficiency loss of the motor, the efficiency of the blades is thus about 60%. Alternatively, the ratio of the height h2 of the rotor blades 243 to the height h1 of the static blades 23 can also range from 1:1.1 to 1:1.4.

The number of rotor blades 243 of the first rotor 24 is different from that of the second rotor 27. For example, the number of rotor blades of the first rotor 24 can be 8, and the number of rotor blades 273 of the second rotor 27 is 9 or 5. In this embodiment, as shown in FIGS. 3A to 3C, the number of the static blades 23 is 7, and noise of the heat dissipation fan is thus reduced. Alternatively, the number of rotor blades of the first rotor is 9, and the number of rotor blades of the second rotor is 8 or 5.

Static blades 23 in the housing 21 can improve working efficiency of the second rotor 27, and increase the airflow pressure. As shown in FIG. 4, the tail ends of the static blades 23 are vertical design; in other word, the front portion 23a is curved, and the rear portion 23b is vertical and extends parallel to a center axis of the heat dissipation fan. Thus, the working efficiency of the second rotor 27 can be greatly improved. Preferably, the length of the rear portion 23b is about ⅓ to ¼ of that of the static blade 23. The rear portion 23b is vertical and parallel to the center axis of the heat dissipation fan. Thus, the efficiency of the rear portion 23b is enhanced and the performance of the heat dissipation fan is optimized.

FIG. 5 shows a heat dissipation fan of the second embodiment of the invention, the structure of which is similar to that of the above-described embodiment except that the hub 241 of the first rotor 24 is conical or tapered, or has an inclined surface, and the inner walls of the heat dissipation holes 242 are inclined. Additionally, the heat dissipation fan further includes a first air-guiding shroud 3 and a second air-guiding shroud 4 respectively disposed on opposite sides of the housing 21. The second air-guiding shroud 4 further includes a plurality of static blades 41 to increase airflow pressure and improve heat dissipation efficiency. The first air-guiding shroud 3 can further include a plurality of static blades. The first air-guiding shroud 3 and the second air-guiding shroud 4 expand outward or are flared, and coupled to the housing 21 by engaging, riveting, screwing, adhesion, or other equivalent means. The housing 21 further includes a plurality of connecting portions 211, and the heat dissipation fan is fixed on an external system frame via holes formed on the connecting portions 211.

The invention provides a heat dissipation fan with optimum heat dissipating efficiency, which is achieved by adjusting the height ratio of the rotor blades to static blades, the collocating numbers of the rotor and static blades, and the shaped design of static blades. Thus, the heat dissipation efficiency and usage rate of space are optimized.

While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.

Claims

1. A heat dissipation fan comprising a housing;a first rotor comprising a shaft and a plurality of rotor blades;a second rotor coupled to the first rotor and comprising a plurality of rotor blades;a base disposed in the housing for supporting the first and second rotors; anda plurality of static blades disposed between the housing and the base, wherein a rear portion of each static blade extends along an axial line of the heat dissipation fan.

2. The heat dissipation fan as claimed in claim 1, wherein a length of the rear portion is ⅓ to ⅕ of that of the static blade.

3. The heat dissipation fan as claimed in claim 1, wherein the second rotor is disposed on the lee side of the first rotor.

4. The heat dissipation fan as claimed in claim 1, wherein an end of the shaft passes through a top surface of a hub of the second rotor to be fixed thereon by riveting, screwing, adhesion, or other equivalent means.

5. The heat dissipation fan as claimed in claim 1, further comprising a first air-guiding shroud disposed on a side of the housing.

6. The heat dissipation fan as claimed in claim 5, further comprising a second air-guiding shroud disposed on another side of the housing.

7. The heat dissipation fan as claimed in claim 6, wherein the first or second air-guiding shroud comprises a plurality of static blades disposed therein.

8. The heat dissipation fan as claimed in claim 6, wherein the first air-guiding shroud or the second air-guiding shroud expands outward or is flared.

9. The heat dissipation fan as claimed in claim 6, wherein the first air-guiding shroud and the second air-guiding shroud are connected to the housing by engaging, riveting, screwing, adhesion, or other equivalent means.

10. The heat dissipation fan as claimed in claim 1, wherein the first rotor and the second rotor comprise a hub and the rotor blades disposed around the hub, respectively, the hub of the first rotor is conical or tapered, or has an inclined surface, and the hub of the second rotor is cup-shaped.

11. The heat dissipation fan as claimed in claim 10, wherein the hubs of the first and second rotors comprise a plurality of heat dissipation holes for allowing airflow to pass therethrough so as to dissipate an internal heat of the fan.

12. The heat dissipation fan as claimed in claim 11, wherein an inner surface of each heat dissipation hole is inclined.

13. The heat dissipation fan as claimed in claim 1, wherein the number of static blades is 7, the number of rotor blades of the first rotor is 9 and the number of rotor blades of the second rotor is 8 or 5 or the number of rotor blades of the first rotor is 8 and the number of rotor blades of the second rotor is 9 or 5.

14. The heat dissipation fan as claimed in claim 1, wherein a height ratio of the rotor blades to the static blades ranges from 1:1.1 to 1:2.2.

15. The heat dissipation fan as claimed in claim 1, wherein the housing further comprises a plurality of connecting portions, and the heat dissipation fan is fixed on an external system frame via holes formed on the connecting portions.

16. A heat dissipation fan comprising a housing;a first rotor comprising a shaft and a plurality of rotor blades;a second rotor coupled to the first rotor and comprising a plurality of rotor blades;a base disposed in the housing supporting the first and second rotors; anda plurality of static blades disposed between the housing and the base, wherein a ratio between a height ratio of the rotor blades to the static blades is ranges from 1:1.1 to 1:2.2.

17. The heat dissipation fan as claimed in claim 16, wherein an end of the shaft passes through a top surface of a hub of the second rotor to be fixed thereon by riveting, screwing, adhesion, or other equivalent means.

18. The heat dissipation fan as claimed in claim 16, further comprising a first air-guiding shroud disposed on a side of the housing, and a second air-guiding shroud disposed on another side of the housing.

19. The heat dissipation fan as claimed in claim 18, wherein the first or second air-guiding shroud comprises a plurality of static blades disposed therein, and the first air-guiding shroud or the second air-guiding shroud expands outward or is flared.

20. The heat dissipation fan as claimed in claim 16, wherein a front portion of each static blade is curved, and a rear portion of each static blade extends along an axial line of the heat dissipation fan, and a length of the rear portion is ⅓ to ⅕ of that of the static blade.