Abstract:
A heat dissipation device includes a heat sink ( 10 ), a fan holder ( 20 ) located on the heat sink and a fan ( 30 ) mounted on the fan holder. The heat sink includes a plurality of fins ( 14 ) extending therefrom and defines two slots ( 16 ) in two opposite outmost fins thereof. The fan holder includes two brackets ( 200 ) each having a positioning rib ( 212 ) engaged in a corresponding slot of the heat sink and resisting the outmost fin to thereby mount the fan holder to the heat sink.

Description:
1. FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to a heat dissipation device, and more particularly to a heat dissipation device incorporating a fan for dissipating heat generated by an electronic device. The heat dissipation device has a fan holder for attachment of the fan. 
       2. DESCRIPTION OF RELATED ART 
       [0002]    It is well known that during operation computer electronic devices such as central processing units (CPUs) can generate large amounts of heat. The heat must be quickly removed from the electronic device to prevent it from becoming unstable or being damaged. Typically, a heat sink is attached to an outer surface of the electronic device to absorb heat from the electronic device, and the heat absorbed by the heat sink is then dissipated to ambient air. 
         [0003]    Generally, in order to improve heat dissipation efficiency of a heat sink, a fan is desired to provide forced airflow to the heat sink. Usually, the fan is mounted to the heat sink by a fan holder attached to the heat sink. Conventionally, the heat sink mainly comprises a heat-conducting base contacting a heat generating electronic device and a plurality of heat dissipating fins extending from one face of the base. A plurality of screw threads is formed in two outermost fins at each side of the heat sink. The fan holder defines a plurality of fixing apertures corresponding to the screw threads of the heat sink. Pluralities of screws are engaged in the fixing apertures of the fan holder and the screw threads of the heat sink, thereby fastening the fan holder to the heat sink. The fan holder is mounted on the heat sink by using a number of screws. The structure can mount the fan to the heat sink, but a problem is that complexities arise when installing the fan holder to the heat sink using multiple screws. 
         [0004]    What is needed, therefore, is a heat dissipation device incorporating a fan holder easily mounted to a heat sink thereof. 
       SUMMARY OF THE INVENTION 
       [0005]    A heat dissipation device in accordance with a preferred embodiment of the present invention includes a heat sink, a fan holder located on the heat sink and a fan mounted on the fan holder. The heat sink includes a plurality of fins extending therefrom and defines two slots in two opposite outmost fins thereof. The fan holder includes two brackets each having a positioning rib engaged in a corresponding slot of the heat sink and resisting the outmost fin to thereby mount the fan holder to the heat sink. 
         [0006]    Other advantages and novel features will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings, in which: 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Many aspects of the present apparatus and method can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present apparatus and method. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0008]      FIG. 1  is an exploded, isometric view of a heat dissipation device in accordance with a preferred embodiment of the present invention; 
           [0009]      FIG. 2  is an assembled side view of a fan holder and a heat sink of the heat dissipation device of  FIG. 1 ; and 
           [0010]      FIG. 3  is an assembled view of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0011]      FIG. 1  illustrates a heat dissipation device in accordance with a preferred embodiment of the present invention. The heat dissipation device comprises a heat sink  10 , a fan holder  20  and a fan  30  mounted on the fan holder  20 . 
         [0012]    The heat sink  10  is integrally extruded from heat conductive material, such as aluminum, and comprises a base  12  and a plurality of fins  14  perpendicularly extending from the base  12 . The base  12  has a bottom face (not labeled) for contacting a heat-generating electronic device such as a CPU (not shown). A pair of slots  16  are defined in outer surfaces of two opposite outmost fins  14  of the heat sink  10 , respectively. Each of the two opposite outmost fins  14  comprises a first portion  140  extending upwardly from the base  12  and a second portion  142  extending upwardly from a lateral side of the first portion  140 . The first portion  140  has a gradually decreasing thickness toward a top of the first portion  140  away from the base  12 . The slot  16  is defined when the second portion  142  is recessed in a connecting portion (not labeled) between the first portion  140  and the second portion  142 . Seen from a direction of a lateral side view (i.e.,  FIG. 2 ) of the heat sink  10 , the second portion  142  has an ear-like shape. The second portion  142  has an inclined surface  144  corresponding to a top end (not labeled) of the first portion  140 , for facilitating an engagement with the fan holder  20 . The inclined surface  144  extends upwardly and outwardly along a bottom-to-top direction of the heat sink  10 . The top end of the first portion  140  is located outside of and adjacent to the slot  16 . 
         [0013]    The fan holder  20  comprises a pair of brackets  200  attached on a top of the heat sink  10 . Each bracket  200  comprises a first plate  210  arranged at a lateral side of the heat sink  10  and a second plate  220  connecting with the first plate  210  and attached to the top of the heat sink  10 . The first plate  210  has a rectangular shape and has a pair of positioning ribs  212  perpendicularly inwardly protruding from an inner side (not labeled) thereof. The positioning ribs  212  are stamped from the first plate  210  so that a pair of recesses  214  are defined in an opposing outer side (not labeled) of the first plate  210 , located corresponding to the positioning ribs  212 . A pair of threaded holes  222  are defined in opposing lateral edges of the second plate  220 . The second plate  220  has an arc-shaped side edge  224  between the threaded holes  222 . The arc-shaped side edges  224  of the second plates  220  of the brackets  200  together define a round opening (not labeled) below the fan  30 , for guiding airflow produced by the fan  30  to pass through to cool the fins  14  of the heat sink  10 . The fan  30  comprises a rectangular frame  32 . The frame  32  defines four orifices  320  in four corners corresponding to the threaded holes  222  of the second plates  220  of the brackets  200  of the fan holder  20 . 
         [0014]    Referring to  FIG. 2 , in order to assemble the fan holder  20  to the heat sink  10 , bottoms of the first plates  210  of the brackets  200  of the fan holder  20  are slipped over the inclined surface  144  and inserted into the slots  16  of the opposite outmost fins  14  of the heat sink  10 . The positioning ribs  212  of the first plates  210  of the brackets  200  are held in the slots  16  and resist the second portion  142  of the outmost fin  14 . The positioning ribs  212  abut against a bottom surface (not labeled) of the second portion  142  of the outmost fin  14 , which is extended inwardly from a bottom end of the inclined surface  144 . The first plate  210  has an outer surface at a lower end thereof, which abuts against the top end of the first portion  140 , and an inner surface above the position ribs  212 , which abut against the inclined surface  144 . 
         [0015]    Referring to  FIGS. 1-3 , the second plates  220  of the brackets  200  of the fan holder  20  are located on the top of the heat sink  10  and the fan  30  is arranged on the brackets  200  of the fan holder  20 . Four screws  40  are extended through the orifices  320  of the frame  32  and screwed in the threaded holes  222  of the second plates  220  of the brackets  200  to thereby fasten the fan  30  to the top of the heat sink  10 , with the airflow produced by the fan  30  passing through the opening (not labeled) of the fan holder  20  to cool the fins  14  of the heat sink  10 . 
         [0016]    In this case, the fan holder  20  can be made by steel instead of aluminum and surfaces of the fan holder  20  are coated with zinc so that the fan holder  20  has advantages of better strength and low cost. 
         [0017]    It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereto described merely being preferred or exemplary embodiments of the invention.