Abstract:
A heat dissipation device includes a heat conducting member ( 10 ) adapted for contacting with a heat generating electronic device and a fin unit ( 30 ). The fin unit defines a central hole ( 300 ) therein and consists of a plurality of fins ( 31 ) around the central hole and clasping each other. The fin unit fits around a periphery of the heat conducting member via the heat conducting member extending in the central hole of the fin unit. A clip ( 40 ) engages with the heat conducting member and the fin unit for providing a pressure to the fin unit such that the fin unit is intimately fastened to the heat conducting member.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates in general to a heat dissipation device used in association with electronic components.  
       DESCRIPTION OF RELATED ART  
       [0002]     With advancement of computer technology, electronic components operate rapidly. It is well known that when the electronic components have become smaller and faster, they generate more heat than ever. If the heat is not dissipated duly, the stability of the operation of the electronic components will be impacted severely. Generally, in order to ensure the electronic components to run normally, heat sinks are used extensively in connection with electronic components. U.S. Pat. No. 5,794,685 discloses an electronic component cooling apparatus. The cooling apparatus includes a heat sink having a cylindrical core and a plurality of radiation fins integrally extending outwards from the core. The radiation fins are formed so as to be limited in their thickness, and a space between two neighboring fins is also limited during manufacture such that number of the fins is limited correspondingly. Such construction fails to provide a sufficient amount of area of fins for radiating the heat, resulting in an insufficient heat dissipation.  
       SUMMARY OF THE INVENTION  
       [0003]     A heat dissipation device in accordance with an embodiment includes a heat conducting member adapted for contacting with a heat generating electronic device and a fin unit. The fin unit defines a central hole therein and consists of a plurality of fins around the central hole and clasping each other. The fin unit fits around a periphery of the heat conducting member via the heat conducting member extending in the central hole of the fin unit. A clip engages with the heat conducting member and the fin unit for providing a pressure to the fin unit such that the fin unit is intimately fastened to the heat conducting member.  
         [0004]     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  
       [0005]     Many aspects of the present device 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 device. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.  
         [0006]      FIG. 1  is an exploded, isometric view of a heat dissipation device in accordance with a preferred embodiment of the present invention;  
         [0007]      FIG. 2  is an assembled view of  FIG. 1   
         [0008]      FIG. 3  is a view similar to  FIG. 2  with a part thereof being cut away;  
         [0009]      FIG. 4  is a perspective view of one fin of a fin unit of  FIG. 1 ;  
         [0010]      FIG. 5  is an assembled view of a locking plate, a heat conducting member and two fins of  FIG. 1 ;  
         [0011]      FIG. 6  is a perspective view of a fin unit of  FIG. 1 ;  
         [0012]      FIG. 7  is an inverted view of  FIG. 6 ; and  
         [0013]      FIG. 8  is a perspective view of one fin of a heat dissipation device according to an alternative embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]     Referring to  FIGS. 1-3 , a heat dissipation device in accordance with a preferred embodiment of the present invention is shown. The heat dissipation device comprises a fin unit  30 , a heat conducting member  10  received in the fin unit  30 , a locking plate  20  combined to a bottom of the heat conducting member  10 , and a clip  40  for securing the fin unit  30  to the heat conducting member  10 .  
         [0015]     The heat conducting member  10  is a frustum which is formed from a cone with a circular base by cutting off a tip of the cone with a cut perpendicular to the height, forming a lower base (not labeled) and an upper base (not labeled) that are circular and parallel to each other. The lower base has a bigger cross-section than that of the upper base and forms an annular pad  12  extending outwardly from an outer surface thereof. A protrusion  14  (shown in  FIG. 3 ) is formed on a bottom of the lower base, for engaging with a heat generating electronic device (not show) located on a printed circuit board (not show). The heat conducting member  10  defines an opening  102  in a top portion thereof having a radius gradually decreased along a top-bottom direction, such that a wall  104  having a thickness gradually increased along the top-bottom direction is formed around the opening  102 . The wall  104  has an inclined surface  106  at an inner surface adjacent to a top thereof. An angle between the inclined surface  106  and an outer surface of the wall  104  is bigger than an angle between the inner surface of the wall  104  and the outer surface of the wall  104 . A bottom of the wall  104  defines a threaded hole  16  located below the opening  102 . The opening  102  is so configured as to reduce the weight of the heat dissipation device and save the cost of the heat dissipation device.  
         [0016]     The locking plate  20  comprises a substantially rectangular body  22  and four fixing legs  24  extending outwardly and downwardly from four corners of the body  22 . Each of the legs  24  has a fixing hole  240  defined in a distal end thereof for fittingly receiving a fastener (not shown) therein. The fasteners are used to attach the heat dissipation device to the printed circuit board. The body  22  has a circular opening  26  defined in a center thereof. A diameter of the opening  26  is smaller than an outer diameter of the annular pad  12 . A gap (not labeled) is formed between an inner surface of the opening  26  and an outer circumferential surface of the heat conducting member  10  when the locking plate  20  is mounted on the annular pad  12 . An engaging portion  28  of the body  22  around the opening  26  is embossed on the locking plate  20 . The engaging portion  28  further extends to the fixing legs  24  to form a star-shaped configuration. The engaging portion  28  is devised for strengthening the locking plate  20  and engaging a bottom of the fin unit  30 .  
         [0017]     The fin unit  30  has a generally cylinder configuration, and comprises a plurality of fins  31  clasping each other to form a central hole  300  therein. The fin unit  30  is mounted around the outer circumferential surface of the heat conducting member  10  by mechanical coupling.  
         [0018]     Please referring to  FIG. 4-5 , each of the fins  31  comprises a plane portion  32  and a curved portion  34  integrally extending from the plane portion  32 . The curved portion  34  curves along a circumferential direction of the heat conducting member  10 . The plane portion  32  comprises an inner inclined edge  32   a  abutting against the outer circumferential surface of the heat conducting member  10 , an upper edge  32   b  connecting with the inner edge  32   a  and a lower edge  32   c  connecting with the inner edge  32   a . A flange  322  is perpendicularly and forward bent from the inner edge  32   a , for contacting with the outer circumferential surface of the heat conducting member  10 . The flange  322  has a length shorter than that of the inner edge  32   a  and a width gradually increased along an up-bottom direction. A wing  324  is perpendicularly and forward bent from the lower edge  32   c . The wing  324  has a width gradually enlarged from an end of the lower edge  32   c  adjacent to the inner edge  32   a  to another end of the lower edge  32   c  far away from the lower edge  32   c  along a length direction of the lower edge  32   c . A tongue  325  is perpendicularly and upwardly bent from a front edge of the wing  324 . A though hole  326  is defined in the wing  324  where the wing  324  is connected with the lower edge  32   c  of the plane portion  32 . A locating tab  327  is stamped from a center of the plane portion  32  such that a locating hole  328  is defined corresponding to the locating tab  327 . The tongue  325  of the fin  31  is inserted in the through hole  326  of an adjacent fin  31  and the locating tab  327  is inserted in the locating hole  328  of the adjacent fin  31  and abuts against the locating tab  327  of the adjacent fin  31  as two adjacent fins  31  are combined together. A protruding hook  36  is formed at a joint of the inner edge  32   a  and the upper edge  32   b . The hook  36  protrudes beyond the inner edge  32   a . The hook  36  has an arcuate edge  36   a  connecting with the inner edge  32   a  and a slant edge  36   b  connecting with the upper edge  32   b . The arcuate edge  36   a  is used for engaging with the inclined surface  106  of the wall  104  of the heat conducting member  10 . The upper edge  32   b  defines a cutout  362  adjacent to the hook  36 . The cutouts  362  of the fins  31  form an annular channel  304  (shown in  FIG. 6 ) for receiving the corresponding clip  40 . A triangular nub  38  is formed at a joint of the inner edge  32   a  and the lower edge  32   c , for inserting into the gap between the inner surface of the opening  26  and the outer circumferential surface of the heat conducting member  10 .  
         [0019]     Please referring to  FIGS. 6-7 , the fin unit  30  is formed by the fins  31  clasping each other. The flanges  322  of the fins  31  cooperatively form a mating surface  302  mating with the outer circumferential surface of the heat conducting member  10 . The plane portions  32  of the fins  31  are perpendicular to the outer circumferential surface of the heat conducting member  10 . The curved portions  34  are bent obliquely respective to the plane portions  32 . The curved portions  34  are used for allowing an airflow to flow through channels (not labeled) formed between the fins  31  and guiding the airflow to blow towards the bottom portion of the heat conducting member  10  and other electronic components around the heat dissipation device.  
         [0020]     Again referring to  FIG. 1  and  FIG. 3 , the clip  40  comprises a cap  42  and a screw  43  used for mounting the cap  42  on the heat conducting member  10 . The cap  42  comprises a circular top plate (not labeled) having a concave portion  420  at a center thereof, and a lateral flange  422  extending downwardly from an edge of the top plate. The lateral flange  422  is engaged in the channel  304  of the fin unit  30 . The concave portion  420  defines a through hole  421  at a center thereof, for permitting passage of the screw  43 . Three spaced cuts  423  are defined in a top plate for facilitating a user to manipulate the cap  42  and increasing the resilience of the cap  42 . The screw  43  comprises an expanded head  430  and a shaft  432  extending downwardly from the head  430 . A distal end of the shaft  432  forms external threads.  
         [0021]     In assembly of the heat dissipation device, the locking plate  20  is assembled to the heat conducting member  10  by fitting the heat conducting member  10  into the opening  26  of the locking plate  20  until a top face of the annular pad  12  of the heat conducting member  10  abuts the locking plate  20 . The heat conducting member  10  has an interferential engagement with the body  22  so that the heat conducting member  10  and the locking plate  20  are securely connected together. Thereafter, the fin unit  30  is assembled to the heat conducting member  10  and rests on the locking plate  20  whereby the fins  31  surround the outer circumferential surface of the heat conducting member  10 . The inner edges  32   a  of the fins  31  intimately engage with the outer circumferential surface of the heat conducting member  10 . The arcuate edges  36   a  of the hooks  36  of the fins  31  abut against the inclined surface  106  of the wall  104  of the heat conducting member  10 . The triangular nubs  38  of the fins  31  are inserted into the gap between the bottom of the outer circumferential surface of the wall  104  and the locking plate  20 . The cap  42  is mounted on the top of the heat conducting member  10  after the fin unit  30  is assembled to the heat conducting member  10 . The lateral flange  422  of the cap  42  is engaged in the channel  304  of the fin unit  30 . The screw  44  passes through the through hole  421  of the cap  42  and extends into the opening  102  of the heat conducting member  10  and further threadedly engaged in the threaded hole  16  of the heat conducting member  10 , whereby the fins  31  are downwardly pressed by the cap  42  to cause the fins  31  to intimately engage with the heat conducting member  10 . Especially, in use of the heat dissipation device, a risk of a vibration by a fan to cause the connection between the fin unit  30  and the heat conducting member  10  to loose is prevented.  
         [0022]     Referring to  FIG. 8 , a heat dissipation device in accordance with an alternative embodiment of the present invention is shown. The heat dissipation device is similar to the heat dissipation device of the previous preferred embodiment, but a fin  31   a  replaces the fin  31  of the fin unit  30  of the previous preferred embodiment. The fin  31   a  comprises a plane portion  32   a , a first bend portion  342   a  bent from the plane portion  32   a  and a second bend portion  344   a  slightly bent from an edge of the first bend portion  342   a . The plane portion  32   a  is similar with the plane portion  32  of the preferred embodiment, and comprises a flange  322   a , a wing  324   a  and a protruding hook  36   a . A cutout  362   a  is defined adjacent to the hook  36   a . A locating tab  327   a  is stamped from a center of the second bend portion  344   a  such that a locating hole  328   a  is defined corresponding to the locating tab  327   a . The first bend portion  342   a  and the second bend portion  344   a  cooperately form a guide portion for guiding the airflow to blow toward the bottom of the heat conducting member  10 .  
         [0023]     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 hereinbefore described merely being preferred or exemplary embodiments of the invention.