Patent Publication Number: US-2007097646-A1

Title: Heat dissipating apparatus for computer add-on cards

Description:
FIELD OF THE INVENTION  
      The present invention relates to a heat dissipating apparatus for computer add-on cards and particularly a heat dissipating apparatus mounted onto a VGA (video graphic array) card for dissipating heat generated by the VGA card, wherein the heat dissipating apparatus has an increased heat dissipating area to thereby enhance heat dissipating efficiency.  
     DESCRIPTION OF RELATED ART  
      Heat sinks serve as cooling devices for heat generating objects such as electronic components or other electronic devices, by absorbing heat generated by such objects and dissipating the absorbed heat into ambient air. Electronic components such as central processing units (CPUs), thermoelectric elements, video graphics array (VGA) cards, and power transistors generate a large amount of heat during operation. When the temperature of an electronic component exceeds a certain level, the electronic component may malfunction or outright fail in the worst case. For this reason, a heat sink is often required to be installed to such a heat generating electronic component to dissipate heat into ambient air.  
      With the rapid development of science and technology, a variety of electronic components or devices have been highly integrated and miniaturized in recent years. As a consequence, techniques for increasing the surface area of heat dissipating fins as much as possible and shortening the heat conducting pathway in heat sinks have been suggested. By these techniques, the dimensions of heat sinks can be reduced with increased heat dissipating efficiency. However, in a conventional manufacturing process, the heat dissipating fins of a conventional heat sink cannot be made thin enough to increase the heat dissipating efficiency. In addition, the cost for manufacturing extremely thin fins by the conventional methods, i.e., metal extrusion or stamping, is high.  
      A Heat sink of a heat dissipation device is commonly installed with a fan to increase the heat dissipating efficiency. For example, the fan is installed on top of the heat sink, and blows air over the heat sink, thereby taking heat away from the heat sink. Although cool air is blown to the heat sink by the fan, most of the air cannot fully flow through the fins and is deflected away midways of heat dissipation fins of the heat sink, so that the cooling efficiency of the fan is not high. Moreover, the mounting of the fan on the top of the heat sink makes a total height of the heat dissipation device be too large to be suitable for use in an environment which has a height limitation. In consideration of the increasing need for cooling high-performance and highly integrated electronic components in a small space, there is a need to develop an effective heat dissipating apparatus capable of sufficiently dissipating the heat generated from such electronic components.  
     SUMMARY OF INVENTION  
      Accordingly, what is needed is a heat dissipating apparatus which has an enlarged heat dissipating area and a more efficient means for removing heat therefrom so as to enhance heat dissipating efficiency.  
      According to a preferred embodiment of the present invention, a heat dissipating apparatus for use with an add-on card, such as a VGA card, comprises a base, a cover spaced from the base, a plurality of fins thermally connecting the cover and the base, a fan positioned on the base to blow air to the fins, and a heat pipe comprising an evaporating portion and a condensing portion. The evaporating portion is sandwiched between the base and the fins. The condensing portion between the fins and the cover. The cover absorbs heat from the fins and the condensing portion of the heat pipe. The fins and the cover dissipate heat to atmosphere immediately. Thus, the heat dissipating apparatus has an increased heat dissipating area and thereby enhancing hat dissipating efficiency.  
      Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings, in which: 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       FIG. 1  is an exploded, isometric view of a heat dissipating apparatus according to a first preferred embodiment of the present invention;  
       FIG. 2  is an assembled view of  FIG. 1 ;  
       FIG. 3  is an exploded, isometric view of a heat dissipating apparatus according to a second preferred embodiment of the present invention;  
       FIG. 4  is an assembled view of  FIG. 3 ; and  
       FIG. 5  is a side view of  FIG. 4 .  
    
    
     DETAILED DESCRIPTION  
       FIGS. 1-2  show a heat dissipating apparatus in accordance with a first preferred embodiment of the present invention. The heat dissipating apparatus mainly comprises a base  70 , a plurality fins  60  soldered to the base  70 , a heat pipe  50  positioned on the base  70  and extending through the fins  60 , a fan  40  located on the base  70 , and a cover  30  soldered onto the base  70  and covering the fins  60 , the fan  40  and the heat pipe  50 . The apparatus is mounted onto an add-on card  20  (such as a VGA card) for dissipating heat generated by a processor (not shown) of the add-on card  20  to achieve effective heat dissipation. For a VGA card, the processor is a GPU (graphic processing unit).  
      The base  70  is secured to the add-on card  20  by four suitable fasteners  10 . Each fin  60  is a single metal piece, and defines first and second parallel rectangular slots  62 ,  64  at a bottom portion thereof.  
      The heat pipe  50  has a U-shaped configuration. The heat pipe  50  is flattened and has a rectangular cross-section. The heat pipe  50  is sandwiched between the base  70  and the bottom portion of the fins  60 . The heat pipe  50  is filled with working fluid therein and has one end forming an evaporating portion  52  located in the first slot  62  of the fins  60  and another end forming a condensing portion  54  located in the second slot  64  of the fins  60 . The first slot  62  is located closer to the fan  40  than the second slot  64 . The evaporating portion  52  is parallel to the condensing portion  54  and adjacent to the fan  40 . The processor of the add-on card  20  engages a bottom face of the base  70  directly below the evaporating portion  52  of the heat pipe  50 . When the evaporating portion  52  absorbs heat from the processor of the add-on card  20 , the working fluid in the evaporating portion  52  becomes vapor. The vapor flows to the condensing portion  54  of the heat pipe  50  and is cooled and condensed into liquid. The condensed working fluid flows back to the evaporating portion  52  by capillarity effect on an inner wall of the heat pipe  50  to complete a heat discharging cycle in the heat pipe  50 . Thereafter, the circle is repeated.  
      The fan  40  is a general radial fan (blower) located on the base  70 . The fan  40  comprises a hollow hub  42  and a plurality of fan blades  44  extending radially from the hub  42 . The fan  40  is mounted to the base  70  by means of screws  402 . Airflow generated by the fan  40  flows through channels formed by the fins  60  to dissipate heat absorbed by the fins  60 .  
      The cover  30  has a top wall (not labeled) spaced from the base  70  and defining an opening  32  therein. The opening  32  is aligned with the fan  40 . The top wall of the cover  30  is soldered onto the fins  60  so that the fins  60  and the top wall of the cover  30  are thermally connected together. A top portion of the fins  60  is contacted with the cover  30 . The cover  30  has a shape similar to that of the base  70 . In the illustrated embodiment the cover  30  is made of aluminum but alternatively it could be made of steel, copper or any other suitable material having good thermal conducting characteristics. Heat absorbed by the base  70  goes through the heat pipe  50  and the fins  60  to the cover  30  to achieve an enlarged heat dissipating area. Accordingly, the heat dissipating efficiency of the heat dissipating apparatus is enhanced; the heat is dissipated not only by the fins  60  but also by the cover  30 .  
      Particularly referring to  FIG. 2 , the fins  60 , the heat pipe  50 , the fan  40  and the cover  30  are installed on the base  70 . One portion of the heat absorbed by the base  70  is distributed over the base  70  along the heat pipe  50 , and is transferred to the fins  60  simultaneously and dissipated to ambient air via the fins  60 . Meanwhile, airflow generated by the fan  40  flows through the fins  60  to take the heat away from the fins  60  thereby increasing a heat dissipating efficiency of the fins  60 . Other portion of the heat absorbed by the base  70  is transferred to the cover  30  via the fins  60  and dissipated by the cover  30  to the ambient air. Heat generated by the processor of the add-on card  20  is thus sufficiently dissipated to the ambient air, and accordingly, the add-on card  20  can operate stably and have an extended life of use. In the present invention, the airflow generated by the fan  40  is drawn from the opening  32  and blown to the fins  60 . Due to the restraint of the base  70  and the cover  30 , the airflow can only entire flow through the fins  60  to leave the heat dissipating apparatus. Thus, the airflow generated by the fan  40  can be sufficiently used to take the heat of the fins  60  away therefrom, and accordingly, the heat dissipation efficiency of the heat dissipating apparatus is promoted.  
       FIGS. 3-5  show a heat dissipating apparatus in accordance with a second preferred embodiment of the present invention. The heat dissipating apparatus of the second preferred embodiment is similar to that of the first preferred embodiment. However, a plurality of fins  60 ′ replaces the fins  60  of the first embodiment and a heat pipe  50 ′ replaces the heat pipe  50 . The fins  60 ′ define a first and a second slot  62 ′,  64 ′ at a bottom portion and a top portion thereof, respectively. The heat pipe  50 ′ has a U-shaped configuration, and comprises an evaporating portion  52 ′ located in the first slot  62 ′, a condensing portion  54 ′ located in the second slot  64 ′ and a connecting portion  53 ′ connecting the evaporating portion  52 ′ and the condensing portion  54 ′. The condensing portion  53 ′ is thermally connected to the cover  30 . In the second preferred embodiment, the evaporating portion  52 ′ and the condensing portion  54 ′ of the heat pipe  50  are flattened and have a rectangular cross-section, respectively. The connecting portion  53 ′ is round and has a circular cross-section.  
      When the second preferred embodiment of invention is in use, one portion of the heat absorbed by the base  70  is transferred to an upper portion of the fins  60 ′ via the condensing portion  54 ′ of the heat pipe  50 ′ and dissipated to ambient air via the fins  60 . Other portion of the heat is transferred to the cover  30  via the fins  60 ′ and the condensing portion  54 ′ of the heat pipe  50 ′, and dissipated by the cover  30  to the ambient air. Thus, the heat dissipating area is increased due to the cover  30 . Heat generated by the processor of the add-on card  20  is dissipated efficiently and quickly. Thus the add-on card  20  can operate stably and have an extended life of use.  
      It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.