Patent Publication Number: US-8974196-B2

Title: Fan and bearing bracket thereof

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a fan and a bearing bracket thereof, and in particular, to a bearing bracket formed by injection and a fan comprising the bearing bracket. 
     2. Description of the Related Art 
     As electronic products are developed toward having higher efficiency, higher frequency range, faster speeds and lighter weights, heat produced in electronic products has increased substantially. As a result of excessive heat, instability may occur in electronic products, thus affecting reliability and life-span of the electronic products. Therefore, efficiently dissipating heat in electronic products has become an important subject matter. One method in particular, uses fans. Fans are commonly utilized to dissipate heat in electronic products, and efficiency and cost reduction of fans are two primary tasks of fan development. 
     As shown in  FIG. 1 , a conventional fan  1  comprises a metal base  11 , a bushing  12 , a motor  13  and an impeller  14 . The bushing  12 , comprising copper or aluminum, and connects with the metal base  11 . The motor  13  is telescoped on the bushing  12 , and a shaft  131  of the motor  13  is disposed within the bushing  12 . The impeller  14 , connected with the outer periphery of the motor  13 , is rotated by the motor  13 . 
       FIG. 2  depicts another conventional fan  1   a,  wherein the bushing  12   a  of the fan  1   a  connects with the metal base  11   a  by a tight fit or gluing. Considering forces to the overall structure, the bushing  12 ,  12   a  of the fan  1 ,  1   a  is made of metal, thus resulting in higher costs. 
     Therefore, providing a bearing bracket, a motor and a fan with a rigid structure and at a lower cost, is a major task of fan development. 
     BRIEF SUMMARY OF THE INVENTION 
     An object of the invention is to provide a bearing bracket and a fan with a rigid structure and at a lower cost. 
     The invention provides a bearing bracket comprising a metal base and a bushing. An opening is formed on a central portion of the metal base. At least one aperture or a reinforcing part is formed adjacent to the opening. The bushing is integrally formed with the metal base by injection molding. 
     The invention provides a fan comprising an impeller, a bearing bracket, a stator structure and a rotor structure. The bearing bracket comprises a metal base and a bushing. The bushing encloses an axial portion or/and a portion of a radial portion of the metal base by injection molding, wherein the axial portion fences the opening. The stator structure is telescoped onto the bushing. The rotor structure is disposed corresponding to the stator structure, and the impeller connects with the rotor structure. 
     The bearing bracket further comprises an anti-vibration member disposed on at least one side surface of the metal base, wherein the anti-vibration member is made of plastic or rubber, and is annular, curved or polygonal. The radial portion of the metal base further comprises at least one through hole or a blind hole, and the anti-vibration member extends into the through hole or the blind hole. The anti-vibration member is adhered to a surface of the radial portion or a recess on the surface of the radial portion. 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
    
    
     
       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 schematic view of a conventional fan; 
         FIG. 2  is a schematic view of another conventional fan; 
         FIG. 3  is a schematic view of a fan of the invention 
         FIGS. 4A to 4D  are schematic views showing the fan of the invention with variant combinations of a metal base and an aperture; 
         FIG. 5A  is a cross sectional view of a variant embodiment of the invention; and 
         FIG. 5B  is a cross sectional view of another variant embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the related figures, an exemplary embodiment of the invention discloses a bearing bracket, a motor and a fan, wherein same components are referenced the same for brevity. 
     As shown in  FIG. 3 , an embodiment of the invention provides a fan comprising an impeller  4 , a bearing bracket  31 , a stator structure  32 , a rotor structure  33  and a magnetizing cover  34 . The bearing bracket  31  comprises a metal base  311  and a bushing  312 . The metal base  311  comprises an opening O on a center portion thereof and a radial portion with at least one aperture H formed adjacent to the opening O. The radial portion extends in the radial direction R (as shown in  FIG. 3 ). The bushing  312  encloses a portion of the radial portion of the metal base  311  by injection molding. The bushing  312  covers the periphery of the opening O and the aperture H. The metal base  311  comprises pure metal or metal alloys. The bushing  312  is made of plastic, such as cold-curing plastic, thermosetting plastic or light-curing plastic, but it is not limited thereto. 
     The stator structure  32  and the rotor structure  33  are received in the magnetizing cover  34 . The stator structure  32 , telescoped onto the bushing  312 , comprises a set of silicon steel sheets. Additionally, a stop portion B is formed on the outer periphery of the bushing  312  to limit the axial movement of the stator structure  32 . The stop portion B contacts the stator structure  32  and fixes the stator structure  32 . The stop portion B is integrally formed with the bushing  312 , and protrudes from the outer periphery of the bushing  312 . Alternatively, the stop portion B is formed by melting a portion of the bushing  312 . 
     The rotor structure  33  is disposed corresponding to the stator structure  32 . The rotor structure  33  comprises a shaft  331  disposed in the bushing  312  and a magnet. The impeller  4  connects with the magnetizing cover  34 . 
     In the embodiment, the stator structure  32 , the rotor structure  33  and the impeller  4  are not limited. The main objective of the invention focuses on injection molding when connecting the bushing  312  and the metal base  311 , thus reducing costs and enhancing structural rigidity. 
     In the embodiment, the metal base  311  and the aperture H comprise many variations.  FIGS. 4A to 4D  are exemplified below, but other variations may be possible. 
     As shown in  FIG. 4A , the metal base  411  comprises a radial portion  413 . The aperture H 1  of the metal base  411  is disposed on the radial portion  413 , and is circular. As shown in  FIG. 4B , the metal base  511  has a radial portion  513  and an axial portion  514 . The aperture H 2  of the metal base  411  is trapezoid and disposed on a border between radial portion and the axial portion. That is, the aperture H 2  extends from the radial portion  513  to the axial portion  514 . The aperture in the embodiment can be in other shapes, such as rectangular or polygonal. 
     Referring to  FIG. 4C , the metal base  611  has a radial portion  613  and an axial portion  614 . Besides the aperture H 3 , the metal base  611  further comprises a reinforcing part  615  disposed on the axial portion  614 . When the bushing  312  and the metal base  611  are integrally formed by injection molding, the reinforcing part  615  is also integrally enclosed. The reinforcing part  615  comprises a protrusion, a recess or a combination thereof. The reinforcing part  615  extends from the periphery of the opening O of the metal base  611 . In the embodiment, the shape of the reinforcing part  615  is not limited. The reinforcing part  615  can be trapezoid. Furthermore, the reinforcing part  715  is T-shaped in  FIG. 4D . The reinforcing part  715  can also be rectangular, circular or polygonal. 
       Fig. 5A  is similar to  Fig. 3 . Referring to  FIG. 5A , the metal base  311  comprises an opening O, an axial portion  3111  surrounding the opening O, and a radial portion  3112 . The axial portion  3111  of the metal base  311  extends in the axial direction Z (as shown in  FIG. 5A ), and the radial portion  3112  extends in the radial direction R (as shown in  FIG. 5A ). The bushing  312  encloses the axial portion  3111  and a portion of the radial portion  3112  of the metal base  311  by injection molding. The bearing bracket  31  of the fan further comprises an anti-vibration member  35 . A bearing  36  is disposed between the bearing bracket  31  and the shaft  331  of the impeller  4 . Additionally, the bearing bracket  31  connects with a fan frame or a system frame  9 . 
     In this embodiment, the metal base  311  is fastened on the fan frame or the system frame  9  by the radial portion  3112 . The radial portion  3112  has a coupling structure, an engaging structure, a hole or a recess. The anti-vibration member  35  is disposed on at least one side surface of the metal base  311 . It can be disposed between the radial portion  3112  and the fan frame or system frame  9  as shown in  FIG. 5A . The anti-vibration member  35  is made of plastic or rubber, and it can be annular, curved or polygonal. 
     Further, the radial portion  3112  is substantially flat and comprises at least one through hole or blind hole, wherein the anti-vibration member  35  extends into the through hole or the blind hole. Alternatively, the anti-vibration member  35  is adhered to a surface or a recess on the surface of the radial portion  3112 . Otherwise, the metal base  311  can also be fastened on the fan frame of the system frame  9  by screwing through the radial portion  3112 . The screws and the anti-vibration member  35  can be located in the same though hole or different through holes. Therefore, vibration transmitted through the screws is directly absorbed by the anti-vibration member  35 . 
     Moreover, the advantages of the anti-vibration member  35  are to prevent collision between the metal base  311  and the fan frame or the system frame  9 , to reduce noises during the vibration and to increase assembling tolerance between the radial portion  3112  of the metal base  311  and the fan frame or the system frame  9 . 
       Fig. 5B  is similar to  Fig. 5  A.  FIG. 5B  depicts another variant embodiment of the invention showing a cross sectional view of the fan. This embodiment differs from the previous embodiment that the metal base  311  only has the radial portion, and comprising at least one aperture (as shown in dotted line). When the bushing  312  covers the metal base  311 , it extends into the aperture to enhance the connection between the metal base  311  and the bushing  312 . 
     The fan of the invention comprises an integrally formed bushing and metal base by injection molding, and the aperture or the reinforcing part is formed adjacent to the opening of the metal base. Compared to conventional fans, the bushing of the invention comprises an injection-formed plastic bushing, such that the cost is lower than the conventional metal bushing. In addition, the bushing connects with the aperture or the reinforcing part, such that the rigidity of the overall structure is assured. Additionally, when the metal base of the bearing bracket of the fan is applied on the fan frame or the system frame, the anti-vibration member between the metal base and the fan frame or the system frame absorbs vibration produced by the bearing bracket during operation of the fan, avoiding failure of the bearing bracket and the connection between the bearing bracket and the fan frame or the system frame. Moreover, the metal base of the bearing bracket of the fan is substantially flat, and the size of the metal base is not limited, such that the metal base does not require changes when applying to different devices. As a result, the bearing bracket is suitable for all kinds of devices, reducing design cost, manufacturing cost and stocks. 
     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.