Patent Publication Number: US-7909571-B2

Title: Centrifugal fan and frame thereof

Description:
BACKGROUND 
     The invention relates to a frame for a centrifugal fan, and in particular to a frame for a centrifugal fan preventing impurities from entering the interior thereof and reducing reflow of air in a system. 
     Referring to  FIG. 1 , a conventional centrifugal fan comprises a frame  10 , a motor (not shown), and an impeller  30 . The frame  10  comprises an air inlet  11  and an air outlet (not shown). The motor is disposed in the frame  10 , for activating the impeller  30  which comprises a hub  31 , a base plate  32 , and a plurality of blades  33  formed on the base plate  32 . Air enters the centrifugal fan via the air inlet  11  and flows with the rotation of the impeller  30  and exits from the air outlet. 
     Referring to  FIG. 2A  and  FIG. 2B , the conventional centrifugal fan is applied in a system  40  in which electronic members (not shown) are disposed. An air inlet  41  is formed on one side of a housing of the system  40 . As shown in  FIG. 2B , heat in the system  40  is dissipated by the centrifugal fan. Outside air enters the centrifugal fan via the air inlet  41  of the system  40 . Air output from the air outlet of the centrifugal fan is forwarded to the interior of the system  40 . The aforementioned operation of heat dissipation, however, has a drawback. An airflow output from the air outlet of the centrifugal fan causes reflow of air, reducing heat dissipation from the system  40 . 
     To reduce the reflow of air, another system, as shown in  FIG. 3 , comprises a guide plate  42  disposed in a housing of the system and tightly abutting the centrifugal fan to reduce the reflow of air. 
     Specifically, as shown in  FIG. 3 , the guide plate  42  abuts the centrifugal fan by a surface thereof contacting a turning corner on an outer frame of the centrifugal fan. Accordingly, the guide plate  42  contacts the centrifugal fan merely in a linear manner. Thus, reflow of air is also easily generated when linear contact between the guide plate  42  and the centrifugal fan is incomplete. 
     Moreover, as the air inlet  41  of the system  40  is connected to the exterior thereof, impurities, such as dust and water drops, may enter the system  40  via the air inlet  41 . The impurities may also enter the centrifugal fan, causing damage thereto. 
     Hence, there is a need for a frame of a centrifugal fan to reduce reflow of air in a system and enhance heat dissipation thereof. In addition, external impurities can be reduced in the centrifugal fan such that damage thereto is prevented. 
     SUMMARY 
     Accordingly, an embodiment of the invention provides a frame for a centrifugal fan. The frame comprises an air inlet and an air outlet. A first barricade is formed on one side of the air inlet and extends outward, preventing impurities from entering the air inlet. 
     Another embodiment of the invention provides a frame for a centrifugal fan. The frame comprises an air inlet and an air outlet. A second barricade is formed on part of the periphery of the air outlet and extends outward. The second barricade tightly abuts a system for preventing reflow of air, enhancing heat dissipation, and increasing rigidity of the frame. 
     Yet another embodiment of the invention provides a centrifugal fan comprising a frame, an impeller, and a motor. The frame comprises an air inlet and an air outlet. A barricade is formed on one side of the air inlet and extends outward, preventing impurities from entering the air inlet. The impeller is disposed in the frame. The motor is disposed in the frame for activating the impeller. 
    
    
     
       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 an exploded perspective view of a conventional centrifugal fan; 
         FIG. 2A  is a schematic top view of a conventional centrifugal fan applied in a system; 
         FIG. 2B  is a schematic side view of a conventional centrifugal fan applied in a system; 
         FIG. 3  is a schematic side view of a conventional centrifugal fan applied in another system; 
         FIG. 4A  is a schematic perspective view of the centrifugal fan of an embodiment of the invention; 
         FIG. 4B  is a schematic side view of  FIG. 4A ; 
         FIG. 5  is an exploded side view of  FIG. 4A ; 
         FIG. 6A  is a schematic top view of a centrifugal fan of an embodiment of the invention applied in a system; 
         FIG. 6B  is a schematic side view of a centrifugal fan of an embodiment of the invention applied in a system; 
         FIG. 6C  is a schematic front view of a centrifugal fan of an embodiment of the invention applied in a system; 
         FIG. 7A  is a schematic top view of a first barricade of a centrifugal fan of an embodiment of the invention; 
         FIG. 7B  is another schematic top view of a first barricade of a centrifugal fan of an embodiment of the invention; 
         FIG. 8  is a schematic side view of a centrifugal fan of an embodiment of the invention applied in another system; and 
         FIGS. 9A ,  9 B,  9 C, and  9 D are partial views of different top ends of the second barricades of the centrifugal fan of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 4A ,  4 B, and  5 , the centrifugal fan comprises a hollow frame  50 , an impeller  60 , and a motor (not shown) for activating the impeller  60 . The motor and impeller  60  are disposed in the frame  50 . 
     The frame  50  comprises a top cover  501  and a bottom cover  502 . The frame  50  further comprises an axial air inlet  503  and a sideward air outlet  504 . Specifically, the air inlet  503  penetrates the top cover  501  and is formed along an axial direction thereof. The air outlet  504  is formed between a periphery of the top cover  501  and a corresponding periphery of the bottom cover  502 . The top cover  501  comprises a plurality of U-shaped retaining rings (first engaging portions)  5011  downwardly formed on the periphery thereof. The bottom cover  502  comprises a plurality of protrusions (second engaging portions)  5021  formed on the sidewall thereof. The U-shaped retaining rings  5011  respectively engage the protrusions  5021  to form the frame  50 . In this embodiment, the profile of the frame  50  is substantially D-shaped. Namely, the air outlet  504  outwardly expands from interior of the frame  50  and with respect to an opposite end thereof. The profile of the frame  50  is designed according to the flow of air therein, normalizing the speed and amount of airflow output from the air outlet  504 . Thus, heat generated by a heat source with a large area can be dissipated, and space required by the frame  50  can be reduced. 
     Moreover, a first barricade  505  is axially and upwardly formed on part of the periphery of the air inlet  503  of the top cover  501 . The height, curved length, and forming position of the first barricade  505  can be designed as required. Specifically, the first barricade  505  may not be formed on the periphery of the air inlet  503 , the curvature thereof may not be the same as that of the periphery of the air inlet  503 , and the barricade  505  may not be vertically and upwardly formed. Namely, the first barricade  505  may be separated from the air inlet  503  by a distance, the curvature thereof may be greater or less than that of the periphery of the air inlet  503 , and the barricade  505  may be upwardly formed with any sloped angle. 
     Moreover, a second barricade  506  is formed on part of the periphery of the air outlet  504  and extends outwardly and axially. The height of the second barricade  506  can be designed as required. To reduce space occupied by the frame  50 , the air inlet  503  and air outlet  504  can be close to each other. As a portion of the top cover  501  between the air inlet  503  and the air outlet  504  is weak, the second barricade  506  can enhance rigidity thereof. Specifically, part of the periphery of the air inlet  503  near one side of the air outlet  504  is straight and covers part of blades of the impeller  60 . Reflow of air can thus be reduced. 
     Referring to  FIGS. 6A ,  6 B, and  6 C, the centrifugal fan can be applied in a system  40  with a housing. Electronic members (not shown) and the centrifugal fan are disposed in the housing. An air inlet  41  is formed on one side of the housing. Heat in the system  40  is dissipated by operation of the centrifugal fan. Specifically, air enters the centrifugal fan via the air inlet  41  of the system  40  and is forwarded to the interior of the system  40  via the air outlet  504  of the centrifugal fan. When the centrifugal fan is disposed in the system  40 , the first barricade  505  of the frame  50  faces the air inlet  41  of the system  40 , which prevents impurities, such as dust and liquid, from entering the centrifugal fan. The centrifugal fan is thus not damaged. Since the first barricade  505  is mainly to prevent the impurities from entering the centrifugal fan via the air inlet  41  of the system  40 , the first barricade  505  can also be designed to have a straight and flat profile. Nevertheless, the profile and forming position of the first barricade  505  shown in  FIG. 4A  and  FIG. 6A  provide a better prevention of impurities entering the centrifugal fan and thus do not adversely affect flow of air. Alternatively, the air inlet  41  may be formed on different sides of the housing of the system  40 . Similarly, the first barricade  505  may be formed in different positions on the centrifugal fan, as shown in  FIG. 7A  and  FIG. 7B . 
     Referring to  FIG. 8 , the centrifugal fan can be applied in another system  40  with a housing and a guide plate  42 . The guide plate  42  is disposed in the housing. When the centrifugal fan is disposed in the system  40 , the second barricade  506  of the frame  50  tightly abuts the guide plate  42 , such that reflow of air is reduced and heat dissipation of the system  40  is enhanced. Moreover, the second barricade  506  can be designed as required. For example, as shown in  FIGS. 9A ,  9 B,  9 C, and  9 D, a top end (or an extending end) of the second barricade  506  can be formed with a planar, curved, or sloped surface. Thus, better abutment between the second barricade  506  and the guide plate  42  is achieved. 
     In conclusion, in the disclosed centrifugal fan, the first barricade prevents impurities from entering, and the second barricade tightly abuts the guide plate of the system. Thus, reflow of air is prevented and heat dissipation from the system is enhanced. 
     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.