BACKGROUND
The invention relates to heat dissipation fans, and in particular to housings for axial flow fans.
Electronic devices generally produce heat during operation, and thus, heat-dissipating devices or fan assemblies are required. As the demand for heat-dissipation increases, fans must provide enhanced performance.
As shown in FIG. 1, a conventional axial flow fan includes a casing 90, a stator 91, and an impeller 93. The stator 91 is disposed in the casing 90. The impeller 93 includes a rotary shaft 94 inserted in an axial hole of the stator 91 and supported by bearings 92. When the impeller 93 rotates, airflow is directed to an outlet of the casing 90 by blades 95 of the impeller 93. A plurality of ribs 96 are disposed at the outlet of the casing 90. The ribs 96 are substantially a quarter of a circle in cross section, as shown in FIG. 2. The airflow produced by the impeller 93 is blocked by the ribs 96, resulting in different directions of airflow as shown by the arrows in FIG. 2. Noise is produced due to air turbulence near the ribs 96, and the air pressure at the outlet is reduced.
SUMMARY
Heat dissipation fans and housings thereof are provided. An exemplary embodiment of a housing of a heat dissipation fan comprises an outer frame, a base, and a plurality of air-guiding elements. The base is disposed in the outer frame. The air-guiding elements, disposed between the base and the outer frame, comprise a first curved surface, a second curved surface, and a bottom surface.
Further provided is another housing comprising an outer frame, a base, and a plurality of air-guiding elements. The base is disposed in the outer frame. The air-guiding elements, disposed between the base and the outer frame, comprise a first sloped surface and a second sloped surface, connected thereto. The sloped surfaces are arch, convex, concave, or sloped at different angles.
An exemplary embodiment of a heat dissipation fan comprises an outer frame, an impeller, a base, and a plurality of air-guiding elements. The impeller comprises a hub and a plurality of blades encircling the hub. The base is disposed in the outer frame. The air-guiding elements, disposed between the base and the outer frame, comprise a first curved surface and a second curved surface.
The blades comprise an inner edge lower than a top surface of the hub. The hub comprises a curved upper edge.
The heat-dissipation device further comprises a metal shell with a plurality of holes defined therein, and the hub comprises an engaging element engaged in the holes such that the hub is telescoped outside the metal shell.
The first curved surface and the second curved surface form different acute angles relative to a plane of the bottom surface, respectively, between 5° and 60°. Also, the first curved surface and the second curved surface have different curvatures.
The air-guiding elements further comprise a horizontal bottom surface. The curved surfaces are arch, convex, concave, or sloped at different angles.
The air-guiding elements are incomplete stator blades with a cross section area greater than or equal to one-third of the cross section area of the blades. The cross section area of the air-guiding elements may be less than that of the blades. The height of the air-guiding elements is substantially one-third to half that of the blades.
The outer frame comprises an outwardly extended portion, located at an outlet or an inlet thereof to increase air volume. The air-guiding elements are connected between the extended portion and the base. Each of the air-guiding elements comprises a fixed end and a free end. The fixed end is connected to the base, and the free end extends in the direction of the extended portion. Alternatively, the fixed end may be connected to the extended portion, and the free end extends in the direction of the base. Each of the air-guiding elements can comprise fixed ends connected to the extended portion and free ends extending in the direction of the base, and others of the air-guiding elements comprise fixed ends connected to the base and free ends extending in the direction of the extended portion.
A cross section of the air-guiding elements gradually increases or decreases from the base to the extended portion.
Additionally, the outer frame, the casing, and the air-guiding elements are integrally formed, as a monolithic piece.
The base comprises a plurality of reinforced structures to increase strength thereof.
DESCRIPTION OF THE DRAWINGS
The invention can be more fully understood by reading the subsequent detailed description in conjunction with the examples and references made to the accompanying drawings, wherein:
FIG. 1 is a schematic exploded view of a conventional fan;
FIG. 2 is a sectional view of FIG. 1 along line 2-2;
FIG. 3 is a perspective view of an embodiment of a housing of a heat dissipation fan;
FIG. 4 is a sectional view of an embodiment of a heat dissipation fan;
FIG. 5 is a schematic view showing arrangement of an air-guiding element and a blade;
FIGS. 6A and 6B are bottom views of another two embodiments of housings of heat dissipation fans;
FIG. 7 is a plot showing the relationship between air pressure and air volume of an embodiment of a heat dissipation fan, compared with a conventional fan.
DETAILED DESCRIPTION
Heat dissipation fans and housings thereof are provided. FIG. 3 is a perspective view of an embodiment of a housing 3 of a heat dissipation fan. The housing 3 includes an outer frame 30, a base 31, and a plurality of air-guiding elements 32. The base 31 is disposed in the outer frame 30 to support blades (not shown) of an impeller (not shown) of the heat dissipation fan. The air-guiding elements 32 are disposed between the base 31 and the outer frame 30 in the vicinity of an outlet. The air-guiding elements 32 can also be disposed at an inlet or at both the inlet and the outlet of the housing. The outer frame 30, while square as shown in FIG. 3, can also be rectangular or circular. The outer frame 30, the base 31, and the air-guiding elements 32 can be integrally formed as a monolithic piece by injection molding using materials such as plastic or metal. The base 31 can have a plurality of reinforced structures 31a to increase strength thereof.
As shown in FIG. 4, the heat dissipation fan 10 includes an impeller 4. The impeller 4 has a hub 41 and a plurality of blades 42 encircling the hub 41. Each of the blades 42 has an inner edge lower than a top surface of the hub 41. The hub 41 has a top edge with curved structure 41a such that airflow is smoothly guided to the blades 42. The heat dissipation fan 10 further includes a metal shell 43 with a plurality of holes defined therein. A top portion of the hub 41 has an engaging element 41b engaged in the holes of the metal shell 43 to telescope the hub 41 outside the metal shell 43. The holes of the metal shell 43 are not shown, since the engaging element 41b is disposed therein. The heat dissipation fan 10 further includes a driving device 5 disposed in the metal shell 43 or the hub 41 to rotate the impeller 4, producing airflow.
As shown in FIG. 5, each of the air-guiding elements 32 has a first curved surface 321, a second curved surface 322, and a horizontal bottom surface 323. The first curved surface 321 is located on the windward side, forming an inclined angle θ1 relative to a plane B of the horizontal bottom surface 323, shown by a dotted line. The second curved surface 322 is located at the opposite side of incoming airflow. The second curved surface 322 forms an inclined angle θ2 relative to a plane B of the bottom surface 323. Note that the angles θ1 and θ2 are different. The angles are preferably acute angles between 5° and 60°. The first curved surface 321 and the second curved surface 322 are arch, convex, concave, or sloped at an angle and can intersect at a point A in the vicinity of an end of the blade 42 such that airflow through the blades 42 is transferred to static pressure. Thus, air pressure of the heat dissipation fan is increased.
The air-guiding elements 32 are incomplete stator blades with cross section area greater than or equal to one-third of the cross section area of the blades 42. Alternatively, the cross section area of the air-guiding elements 32 is less than that of the blades 42. Namely, if the blades 42 are wing-shaped, the air-guiding elements 32 have a similar wing-shape with end portions thereof being cut off. Thus, the height of the air-guiding elements 32 is substantially one-third to half that of the blades 42.
As shown in FIG. 4, the outer frame 30 includes an outwardly extended portion 33a, located at an outlet, and another outwardly extended portion 33b located at an inlet thereof to increase air volume. The air-guiding elements 32 are connected between the extended portion 33a and the base 31. Note that the connection therebetween is not limited. For example, some of the air-guiding elements 32 have a fixed end connected to the base 31 and a free end extending in the direction of the extended portion 33a, as shown in FIG. 6A. Alternatively, some of the air-guiding elements 32 have a fixed end connected to the extended portion 33a and a free end extending in the direction of the base 31, as shown in FIG. 6B. Alternativley, the air-guiding elements 32 can be divided into two portions, one portion respectively having a fixed end connected to the extended portion 33a and a free end extending in the direction of the base 31, and the other portion respectively having a fixed end connected to the base 31 and a free end thereof extending in the direction of the extended portion 33a. In addition, the cross section of the air-guiding elements 32 is constant or can gradually increase or decrease from the base 31 to the extended portion 33a. The quantities of the air-guiding elements 32 can be less than those of the blades 42.
FIG. 7 is a plot showing the relationship between air pressure and air volume of the heat dissipation fan of FIGS. 3 to 5, compared with a conventional fan of FIG. 1. The dotted-line curve represents the plot of the conventional fan, and the solid-line curve represents that of the heat dissipation fan with the air-guiding elements of the present invention. It can be seen that the air-guiding elements can greatly increase air pressure while reducing noise level. In addition, the air-guiding elements of the present invention can also improve the performance of speed control of the axial-flow fan.
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.
Patent Application
20060039784
