Abstract:
A heat dissipation device includes a heat sink including a base and a plurality of fins on the base. Each of the fins includes a body stamped with at least a flap toward an adjacent fin. A plurality of passages is defined between adjacent fins. A fan is attached to the heat sink for providing forced airflow to the heat sink. The at least a flap of the body of each of the fins leans from the fan toward a heat-accumulating portion of the heat sink to guide a stream of the airflow from the fan to the heat-accumulating portion of the heat sink. The heat-accumulating portion is either a connecting portion between the fins and heat pipes, or the base of the heat sink.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to a heat dissipation device, and more particularly to a heat dissipation device used for dissipating heat generated by an electronic device. 
         [0003]    2. Description of Related Art 
         [0004]    With advancement of computer technology, electronic devices are operating at ever higher speeds. It is well known that the more rapidly the electronic devices operate, the more heat they generate. If the heat is not dissipated, the stability of the operation of the electronic devices will be impacted severely. Generally, in order for the electronic device to run normally a heat dissipation device is used to dissipate the heat generated by the electronic device. 
         [0005]    Conventionally, a heat dissipation device comprises a heat sink which has a base and a plurality of fins mounted on the base. The fins are oriented parallel to each other and arranged on the base with spaces between adjacent fins. Therefore, pluralities of passages are defined between the fins to allow airflow to pass therethrough. Usually the heat dissipation device further comprises a fan located aside the heat sink for providing forced airflow to the heat sink. The heat generated by the electronic device accumulates on the base. Sometimes a heat pipe is used for transferring the heat from the base to the fins. In the conventional design, there is insufficient airflow from the fan of the heat dissipation device can be distributed to the base or the heat pipe to duly remove the heat accumulated therein. Heat dissipation capacity of the heat dissipation device cannot meet heat dissipation requirements for the up-to-date electronic devices. Consequently, in order to improve the heat dissipation capacity, the heat dissipation device needs to be improved. 
         [0006]    What is needed, therefore, is a heat dissipation device having greater heat dissipation capacity. 
       SUMMARY OF THE INVENTION 
       [0007]    A heat dissipation device in accordance with a preferred embodiment of the present invention is used for dissipating heat generated by an electronic device. The heat dissipation device comprises a heat sink comprising a base and a plurality of fins on the base. Each of the fins comprises a body stamped with at least a flap toward an adjacent fin. A plurality of passages is defined with one between each fin and its adjacent fin. A fan is attached to the heat sink for providing forced airflow to the heat sink. The at least a flap of the body of each of the fins leans from the fan toward a heat-accumulating portion of the heat sink to guide a stream of airflow from the fan to the heat-accumulating portion of the heat sink. The heat-accumulating portion according to the preferred embodiment is a connecting portion between heat pipes and the fins of the heat sink. The heat-accumulating portion according to another embodiment is the base of the heat sink. 
         [0008]    Other advantages and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Many aspects of the present apparatus 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. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0010]      FIG. 1  is an exploded, isometric view of a heat dissipation device in accordance with a preferred embodiment of the present invention; 
           [0011]      FIG. 2  shows a fin set of the heat dissipation device of  FIG. 1 ; 
           [0012]      FIG. 3  is an assembled view of  FIG. 1 ; 
           [0013]      FIG. 4  is a plan view of  FIG. 3 ; 
           [0014]      FIG. 5  is an exploded, isometric view of a heat dissipation device in accordance with an alternative embodiment of the present invention; 
           [0015]      FIG. 6  shows a fin set of the heat dissipation device of  FIG. 5 ; 
           [0016]      FIG. 7  is an assembled view of  FIG. 5 ; and 
           [0017]      FIG. 8  is a side view of  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    Referring to  FIG. 1 , a heat dissipation device in accordance with a preferred embodiment of the present invention comprises a heat sink (not labeled) having a base  10  and a fin set  30  on the base  10 , three heat pipes  50  connecting the base  10  and the fin set  30  for transferring heat from the base  10  to the fin set  30 , and a fan  70  attached to a side of the fin set  30  by a fan holder  60 . 
         [0019]    The base  10  comprises a substantially rectangular heat receiver  100 , and four fixing legs  110  extending outwardly from four corners of the heat receiver  100 . The heat receiver  100  is made from a highly heat conductive metal such as copper, aluminum or the like. A top face of the heat receiver  100  defines three parallel grooves (not labeled) therein. A bottom face of the heat receiver  100  is flat for thermally contacting a heat generating electronic device. Each of the fixing legs  110  defines a fixing hole (not labeled) adjacent to a distal end thereof for fixing the heat dissipation device to a printed circuit board (not shown) by a fastener  120  engaging in the fixing hole. 
         [0020]    Referring also to  FIG. 2 , the fin set  30  comprises a plurality of fins  300  assembled together. Each fin  300  comprises a main body  310 , two flanges  320  perpendicularly extending from two opposite lateral edges of the main body  310 . The main body  310  has a linear front edge (not labeled) perpendicular to the flanges  320  and an opposite curved rear edge (not labeled) projecting rearwards beyond the flanges  320 . Two spaced flaps  311  are stamped from the main body  310 , leaving two slits  314  between the two flaps  311  in the main body  310  of the fin  300 . Each flap  311  is oriented substantially perpendicular to the main body  310  and has a height equal to or less than that of the flange  320 . Each of the two flaps  311  has a first end adjacent to the linear front edge of the main body  310  and a second end extending toward the curved rear edge of the main body  310 . The two flaps  311  have the first ends thereof adjacent to each other and the second ends apart from each other, thereby defining a wedge-shaped portion in a middle portion of the main body  310 . Two rows of through holes  316  are defined outside corresponding flaps  311  in the main body  310 . Each hole  316  is circumferentially surrounded by a collar  317  extending upwardly from the main body  310 . The main body  310  defines two short slots  319  parallel and adjacent to the linear front edge. The flanges  320  of the each fin  300  of the fin set  30  abut the main body  310  of an adjacent fin  300  of the fin set  30 . The flaps  311  of each fin  300  of the fin set  30  extend to the main body  310  of the adjacent fin  300  of the fin set  30 . The through holes  316  of the fins  300  of the fin set  30  cooperatively define three channels  330  outside the flaps  311  of the fin set  30  for receiving the heat pipes  50  therein. Corresponding slots  319  of the fins  300  of the fin set  30  cooperatively define a groove  340  for fixing the fan holder  60 . A plurality of passages (not labeled) is defined between adjacent fins  300  of the fin set  30 . 
         [0021]    Referring again to  FIG. 1 , each heat pipe  50  comprises a first section  510  and two parallel second sections  530  perpendicularly extending from two ends of the first section  510 . A rounder corner (not labeled) is formed at each joint of the first section  510  and the second sections  530 . The first section  510  is received in a corresponding groove of the base  10 . The second section  530  extends beyond the base  10  and is thermally received in a corresponding channel  330  of the fin set  30 . Therefore, the fin set  30  is stacked on the second sections  530  of the heat pipes  50  with the second sections  530  of the heat pipes  50  being located outside the flaps  311  and closer and closer to the flaps  311  along the front-to-rear direction of the fin set  30 . In other words, the flaps  311  lean toward the second sections  530  of the heat pipes  50 . 
         [0022]    The heat dissipation device further comprises a fin unit  40  located between the base  10  and the fin set  30 . The fin unit  40  is folded from a piece of metal sheet, and has a bottom face thermally contacting the top face of the base  10  and a top face contacting a bottom face of the fin set  30 . The fin set  30  is stacked on the second sections  530  of the heat pipes  50 , and is further supported by the fin unit  40 . 
         [0023]    The fan holder  60  comprises two spaced brackets  610 . Each bracket  610  comprises a fixing face  611 , a positioning rib  613  substantially parallel to the fixing face  611 , and a connecting rib  615  connecting the fixing face  611  and the positioning rib  613 . The positioning ribs  613  of the fan holder  60  engage in corresponding grooves  340  of the fin set  30 , thereby attaching the fan holder  60  to the fin set  30 . The fixing faces  611  are located on a front side of the fin set  30  and mount the fan  70  thereon via a plurality of fasteners such as screws  80 . By this, the fan  70  confronts to the passages of the fin set  30  and adjacent to the first ends of the two flaps  311 , therefore, more airflow produced by the fan  70  can be guided to the heat pipes  50  by the flaps  311  of the fin set  30 . 
         [0024]    In use, the base  10  the bottom face contacts the electronic device and absorbs heat from the electronic device. Part of the heat in the base  10  is transferred to the fin unit  40 , and part of the heat is absorbed by the first sections  510  of the heat pipes  50 . Subsequently, the heat in heat pipes  50  is transferred to the fins  300  of the fin set  30  by the second sections  530  of the heat pipes  50 . The heat in the fin set  30 , the fin unit  40  and the heat pipes  50  is duly dissipated to ambient air by the fan  70 . 
         [0025]    According to the heat dissipation device of the preferred embodiment of the present invention, each fin  300  of the fin set  30  of the heat dissipation device has two flaps  311  leaning toward the second sections  530  of the heat pipes  50 ; therefore, more airflow from the fan  70  is guided to the second sections  530  of the heat pipes  50  and portions of the fins  300  around the second sections  530  of the heat pipes  50  by the flaps  311 , as shown in  FIG. 4 . As a result, more heat in the second sections  530  of the heat pipes  50  and the portions of the fins  300  around the second sections  530  is dissipated to ambient air by the airflow, thus avoiding overheating of heat dissipation device. So, heat dissipation capacity of the heat dissipation device of the present invention is improved in comparison with the heat dissipation devices in the related art. 
         [0026]    Referring to  FIGS. 4-8 , a heat dissipation device in accordance with an alternative embodiment of the present invention is shown. The heat dissipation device comprises a base  10   a , a fin set  30   a  located on the base  10   a , and a fan  70  attached to the fin set  30   a  by a fan holder  60   a.    
         [0027]    The base  10   a  comprises a substantially rectangular heat receiver  100   a , and four fixing legs  110   a  integrally extending outwardly from four corners of the heat receiver  100   a . Two opposite lateral faces of the heat receiver  100   a  define two opposite fixing apertures  101   a  for fixing the fan holder  60   a  thereto. Each fixing legs  110   a  defines a fixing hole  111   a  adjacent to a distal end thereof for accommodating a fastener (not shown) to fasten the heat dissipation device to the printed circuit board. 
         [0028]    The fin set  30   a  comprises a plurality of fins  300   a  each having bottom and top flanges  320   a  which are substantially perpendicularly extended from a body  310   a  of each fin  300   a . The fin set  30   a  has a top face defining a slot  340  therein for positioning the fan holder  60   a  on the fin set  30   a . The bottom flanges  320   a  of the fins  300   a  of the fin set  30   a  cooperatively form a face thermally contacting a top face of the base  10   a . Two parallel flaps  311   a  are stamped at an angle from the body  310   a  of each fin  300   a , thereby leaving two parallel slits  314   a  in the body  310   a . The flaps  311   a  are substantially perpendicular to the body  310   a . A height of each flap  311   a  from the body  310   a  is substantially equal to or less than that of the flange  320   a . Each flap  311  extends along top left-bottom right direction in the body  310   a  of the fin set  30   a , that is to say each flap  311  extends toward the base  10   a . In other words, each flap  311  has a rear end pointing toward the base  10   a.    
         [0029]    The fan holder  60   a  comprises a U-shaped frame  610   a  and two opposite faceplates  620   a  extending from two lateral sides of the frame  610   a . The frame  610   a  extends a positioning rib  630   a  from a top side thereof. An opening  621   a  is surrounded by the top side of the frame  610   a  and the two faceplates  620   a . The positioning rib  630   a  engages in the slot  340   a  of the fin set  30   a . The two lateral sides of the frame  610   a  have distal bottom ends being fixed to the base  10   a  via bolts  650   a  engaging through holes  660   a  defined therein and corresponding fixing apertures  101   a  of the base  10   a ; in this manner the fan holder  60   a  is fixed to the fin set  30   a . The fan  70  is attached to the faceplates  620   a  by a plurality of screws  710 . As a result the flaps  311   a  of the fin set  30   a  have front ends thereof adjacent to the fan  70 , and rear ends thereof leaning towards the base  10   a , thereby guiding more airflow produced by the fan  70  to the base  10   a  to remove more heat in the base  10   a , as shown in  FIG. 8 . 
         [0030]    It is believed that the present invention and its 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.