Patent Publication Number: US-6709229-B1

Title: Bi-directional incoming air flow fan

Description:
FIELD OF THE INVENTION 
     The invention relates to a bi-directional incoming air flow fan and, more particularly, a bi-directional incoming air flow fan used in a computer assembly to dissipate heat. 
     BACKGROUND OF THE INVENTION 
     Electrical fans are usually used to create an air flow and commonly provide the possibility of changing the outputted air flow direction. Electrical fans can be differentiated from their directions of air flow input and output. Such a differentiation principally leads to a distinction between axial flow type fans and centrifuge type fans. Axial flow type fans have the characteristics of generating an incoming air flow from the rotation axis of the rotary blades, the air flow then is compressed and outputted along the same rotation direction. In contrast, centrifuge type fans generate an axial incoming air flow that is outputted along the radial direction of the rotary blades. 
     Centrifuge type fans are traditionally known as blowers, and are usually comprised of a case and a rotor mounted in the case. It is further common that the case includes an axial face that has an air inlet and a radial face that has an air outlet. The rotor includes a plurality of rotary blades that, once put in rotation, generate an incoming air flow from the air inlet axially disposed, and an outgoing air flow through the air outlet. 
     Because a single face of the above traditional fan is provided with an air inlet, higher air flow amount therefore cannot provided. The prior art thus also provides a centrifuge type fan having a bi-directional incoming air flow. In this type of known fan, two axial faces of the case are respectively provided with an air inlet. However, because the air inlets do not have an equal surface area, incoming air flows are therefore not symmetrical when the rotor rotates, which causes deviation and generation of a floating force or compressive force to which the rotor is negatively subjected to. This results in an increase of friction and vibration of the rotor, which affects the life service of the fan and further generates parasitic noise. 
     SUMMARY OF THE INVENTION 
     It is therefore a principal object of the invention to provide a centrifuge type fan with bi-directional incoming air flow that can achieve a uniform incoming air flow from two sides, thereby reducing a deviation of the rotor and mechanical frictions due to a floating force, while providing a higher amount of air flow output. 
     To accomplish the above and other objectives, a bi-directional incoming air flow fan of the invention comprises a case in which is mounted a rotor that includes a plurality of rotary blades. The case has top and bottom faces that are respectively provided with a first and second air inlet having approximately a same surface area. A side of the case is further provided with an air outlet. Furthermore, each rotary blade includes an upper and lower sides that respectively have an axial flow guiding rib, and a free section that is inclined to form a radial flow section. Thereby, once the rotor is put in rotation, air flow amount and pressure are increased by means of the axial flow guiding ribs that create an uniform air flow. As a result, rotor deviation and floating force are reduced, thereby reducing mechanical frictions and parasitic noise. 
    
    
     To provide a further understanding of the invention, the following detailed description illustrates embodiments and examples of the invention, this detailed description being provided only for illustration of the invention. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings included herein provide a further understanding of the invention. A brief introduction of the drawings is as follows: 
     FIG. 1 is an external perspective view illustrating a bi-directional incoming air flow fan according to an embodiment of the invention; 
     FIG. 2 is an exploded view illustrating the fan according to an embodiment of the invention; 
     FIG. 3 is a perspective view of the lower cover of the invention; and 
     FIG. 4 is a partial section view of the rotor of the invention. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Wherever possible in the following description, like reference numerals will refer to like elements and parts unless otherwise illustrated. 
     Referring to FIG. 1, an external perspective view schematically illustrates a fan with bi-directional incoming air flow according to an embodiment of the invention. As shown in FIG. 1, the fan comprises a case  10  in which is assembled a rotor  40 . 
     FIG. 2 is an exploded view of the fan according to an embodiment of the invention. As illustrated, the case  10  is comprised of lower and upper covers  20 ,  30  assembled with each other. On axial faces corresponding to the rotation axis of the rotor  40 , the lower and upper covers  20 ,  30  are respectively provided with first and second air inlets  21 ,  31  of about a same surface area. On a side of the lower cover  20  is further arranged an air outlet  34 . Meanwhile, a slot  32  (better seen in FIG. 3) is arranged on another side of the lower case  20  corresponding to the periphery of the second air inlet  31 . With further reference to FIG. 4, the rotor  40  is comprised of a central pivot head  50  at a periphery of which are disposed a plurality of rotary blades  60 . The pivot head  50  is further provided with a recess  51  that is arranged in a manner to receive a driving unit (not shown), the connection wires of the driving unit can be received in the slot  32 . 
     Each rotary blade  60  is oriented forward of an inclination angle of 30°-120° and radially extends outward, with a surface area progressively increasing from the interior (head  50  side) to the exterior. Axial flow guiding ribs  61  are respectively arranged on upper and lower sides of each blade  60  to axially guide incoming air flow. A free section of each blade  60  is further forward inclined 15°-60° to form a radial flow section  62  through which air flow is radially guided outward. By means of the axial flow guiding ribs  61  that uniformly guide air flows, the air flow amount and air flow pressure are increased while the deviation and floating force to which the rotor  40  is usually subjected are reduced, mechanical frictions and parasitic noise are therefore favorably reduced. 
     The lower and upper covers  20 ,  30  are provided with connecting portions/slots  22 ,  33  that assemble with one another once the rotor  40  is mounted. 
     In use, the rotor rotates under the drive of the driving unit (not shown). The rotation of the rotary blades  60  drives air flow to axially penetrate the case  10  by means of the axial flow guiding ribs  61 . Due to an identical section of the first and second air inlets  21 ,  31  and a similar direction of the axial flow guiding ribs  61  of the rotary blades  60 , incoming air flow can be therefore uniformly guided from the two sides of the case  10 . Via this balanced incoming air flow, the deviation, floating force, and compressive force to which the rotor  40  is usually subjected to due to air flow circulation are favorably reduced, meanwhile the air flow amount and air flow pressure are increased. Furthermore, the friction between the bearings and other different elements of the fan (not shown) is also reduced, which results in noise reduction and extends the service life of the elements of the fan. Air flow entering the case  10  is oriented toward the air outlet  34  by means of the radial flow sections  62  of the rotary blades  60 . Thereby, a revolution cycle can achieve an air flow that incomes from two sides and radially outgoes. 
     Because the fan of the invention can achieve a bi-directional incoming air flow, the amount of air flow outputted by the fan of the invention is relatively greater than traditional fans having a same volume. Within electric appliances having small placement space while requiring a relatively high thermal dissipation such as computer assemblies, the fan of the invention is therefore particularly advantageous because it allows either a better thermal dissipation for a same fan volume, or a reduced size for equal performance of thermal dissipation, thereby allowing releasing more space. Moreover, by achieving a bi-directional incoming air flow, the invention can reduce the rocking of the rotor  40  in rotation, thereby reducing negative friction and parasitic noise and extending the life span of the fan. 
     It should be apparent to those skilled in the art that the above description is only illustrative of specific embodiments and examples of the invention. The invention should therefore cover various modifications and variations made to the herein-described structure and operations of the invention, provided they fall within the scope of the invention as defined in the following appended claims.