Abstract:
A heat exchange module ( 1 ) is disclosed, which includes an evaporator ( 20 ), a condenser ( 50 ) and a heat sink ( 22 ). The evaporator defines therein a chamber for containing a wick structure ( 20   c ) saturated with a working fluid. The wick structure occupies a portion of the chamber. The condenser is disposed adjacent to the evaporator, wherein the working fluid turns into vapor in the evaporator after absorbing heat of a heat-generating component and the vapor turns into condensate at the condenser after releasing the heat. The heat sink is attached to an outer surface of the evaporator and located in alignment with the wick structure contained in the evaporator.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to an apparatus for transfer or dissipation of heat from heat-generating components, and more particularly to a heat exchange module applicable for removing heat from heat-generating electronic components, wherein the heat exchange module has a loop-type heat exchange device.  
       DESCRIPTION OF RELATED ART  
       [0002]     It is well known that heat is produced by electronic components such as integrated circuit chips during their normal operations. If not timely removed, the generated heat will produce a negative effect to the workability and stability of these electronic components. Therefore, heat-dissipating devices are commonly required to cool these electronic components.  
         [0003]     As an example, a conventional heat-dissipating device generally includes a heat pipe, a heat sink attached to the heat pipe and an electric fan used for producing a forced airflow towards the heat sink. The heat pipe is usually a vacuum casing containing therein a working fluid. A wick structure is preferably provided inside the heat pipe, lining an inner wall of the casing. The heat pipe has an evaporating section for being maintained in thermal contact with a heat-generating component such as a central processing unit (CPU) of a computer, and a condensing section to which the heat sink is attached. When the heat of the CPU is inputted into the heat pipe via its evaporating section, the working fluid contained therein absorbs the heat and turns into vapor. Due to the difference of vapor pressure between the two sections of the heat pipe, the generated vapor moves, with the heat being carried, towards the condensing section where the vapor is condensed into condensate after it releases the heat to the attached heat sink. The heat sink, in combination with the electric fan, further dissipates the heat into ambient environment. The condensate in the condensing section of the heat pipe is then drawn back by the wick structure to the evaporating section where it is again available for evaporation.  
         [0004]     As progress continues to be made in electronic industries, electronic components are produced to have more powerful functions while maintaining an unchanged size or even a smaller size. As a result, the amount of heat generated by these electronic components during their normal operations is commensurately increased, in which case the heat-dissipating devices used to cool these electronic components are required to have a larger heat removal capacity. Thus, many proposed solutions have been made to the foregoing conventional heat-dissipating device in attempt to increase its heat removal capacity, such as adopting multiple heat pipes, increasing the diameter of the heat pipe or increasing the surface area of the heat sink. However, these proposed solutions are ineffective or inapplicable in many applications. As described above, the movement of the vapor is countercurrent to that of the condensate in the heat pipe. As a result of the relative movements of the vapor and the condensate, a shearing force is induced in the heat pipe, which will produce a resistance to the flow of the condensate. If the condensate is not timely sent back to the evaporating section, the heat pipe will suffer a dry-out problem at that section.  
         [0005]     Currently, a loop-type heat exchange device has been proposed in order to overcome the foregoing drawback of the heat pipe. The loop-type heat exchange device generally includes an evaporator, a condenser, a vapor conduit and a liquid conduit. The evaporator contains therein a working fluid. The vapor and liquid conduits each are connected between the evaporator and the condenser by two individual pipes. In operation, the working fluid in the evaporator evaporates into vapor after absorbing the heat from the CPU, and the generated vapor then flows, via the vapor conduit, to the condenser where the vapor is condensed into condensate after its latent heat of evaporation is released. The condensate then returns back to the evaporator via the liquid conduit for being available again for evaporation, thus forming a heat transfer loop.  
         [0006]     In the loop-type heat exchange device, the vapor and the condensate are supposed to flow in the vapor and liquid conduits, respectively, and do not interfere with each other. However, since both the vapor and liquid conduits are connected to the evaporator, if there is no effective mechanism provided in the heat exchange device to maintain the unidirectional working fluid movement along the heat transfer loop, a portion of the vapor generated in the evaporator will possibly move backwards towards and finally enter into the liquid conduit. This portion of vapor flowing backwards will produce significant resistance to the condensate to return back to the evaporator along the liquid conduit, whereby a dry-out problem like that occurred in the heat pipe as set forth above may also happen in the loop-type heat exchange device.  
         [0007]     Therefore, it is desirable to provide a heat exchange module having a loop-type heat exchange device which overcomes the foregoing disadvantages.  
       SUMMARY OF INVENTION  
       [0008]     The present invention relates to a heat exchange module for removing heat from a heat-generating electronic component. The heat exchange module includes a loop-type heat exchange device having an evaporator, a condenser and a heat sink. The evaporator defines therein a chamber for containing a wick structure saturated with a working fluid. The wick structure occupies a portion of the chamber. The condenser is disposed adjacent to the evaporator, wherein the working fluid turns into vapor in the evaporator after absorbing the heat of the heat-generating electronic component and the vapor turns into condensate at the condenser after releasing the heat. The heat sink is attached to an outer surface of the evaporator and is located in alignment with the wick structure contained in the evaporator.  
         [0009]     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  
       [0010]      FIG. 1  is an isometric view of a heat exchange module in accordance with one embodiment of the present invention;  
         [0011]      FIG. 2  is an exploded, isometric view of the heat exchange module of  FIG. 1 ;  
         [0012]      FIG. 3  is an exploded, isometric view of a loop-type heat exchange device of the heat exchange module of  FIG. 2 ;  
         [0013]      FIG. 4  is a partially assembled view of the heat exchange module of  FIG. 2 ;  
         [0014]      FIG. 5  is a fully assembled view of the heat exchange module of  FIG. 2 , in an upside down manner and with a portion thereof being removed for clarification;  
         [0015]      FIG. 6  is an enlarged view of a fastening pin of the heat exchange module of  FIG. 2 ;  
         [0016]      FIG. 7  is an enlarged, isometric view of a mounting plate of the heat exchange module of  FIG. 2  in accordance with another example; and  
         [0017]      FIG. 8  is an enlarged, isometric view of a mounting plate of the heat exchange module of  FIG. 2  in accordance with a further example. 
     
    
     DETAILED DESCRIPTION  
       [0018]      FIGS. 1 and 2  illustrate a heat exchange module  1  in accordance with one embodiment of the present invention. The heat exchange module  1  includes a loop-type heat exchange device  10 , a fan duct  60 , an electric fan  70  (only showing a fan housing thereof), first and second air-guiding members  90   a,    90   b,  a mounting plate  100  and a plurality of fastening pins  110 .  
         [0019]      FIG. 3  shows the loop-type heat exchange device  10  in an upside down manner, which includes an evaporator  20 , two conduits  30  and a condenser  50 . The evaporator  20  includes top and bottom covers  20   a,    20   b  connected together to define a chamber (not labeled) inside the evaporator  20  for receiving a wick structure  20   c  therein. The bottom cover  20   b  is adapted for contacting a heat source (not shown) such as a central processing unit (CPU) of a computer. Although the wick structure  20   c  is schematically shown, it is well known by those skilled in the art that the wick structure  20   c  may include sintered powders or a mesh structure made of metal wires or organic fibers woven together. Before the evaporator  20  is hermetically sealed, a working fluid (not shown) such as water or methanol is injected into the chamber of the evaporator  20  for saturating the wick structure  20   c.  The wick structure  20   c  has a size smaller than the chamber of the evaporator  20  and only occupies a portion of the chamber. As shown in  FIG. 3 , the wick structure  20   c  occupies about one fourth of a total area of the chamber. The chamber of the evaporator  20  is accordingly partitioned by the wick structure  20   c  into two major regions, i.e., a liquid micro-channel region filled with the wick structure  20   c  and an adjacent vapor-gathering region used to gather vapor generated in the evaporator  20 , as will be described in more detail below.  
         [0020]     Each of the conduits  30  has a substantially U-shaped configuration and includes a first pipe section  31  and a second pipe section  33  positioned in parallel with the evaporating section  31 . A wick structure (not shown) is preferably formed inside the second pipe section  33  of each of the conduits  30 . The wick structure for each of the conduits  30  may include fine grooves integrally formed inside the conduits  30 , mesh or bundles of fiber inserted into the conduits  30 , or sintered powders combined to the conduits  30 . The conduits  30  are typically made of high thermally conductive material such as copper, aluminum, silver or their alloys.  
         [0021]     The condenser  50  includes a plurality of vertically spaced metal fins (not labeled). The metal fins of the condenser  50  are stacked along, and maintained in thermal contact with, the first and second pipe sections  31 ,  33  of each of the conduits  30 , as particularly shown in  FIG. 4 . The first and second pipe sections  31 ,  33  of each of the conduits  30  are connected to the evaporator  20 , wherein the first pipe sections  31  communicate with the vapor-gathering region while the second pipe sections  33  communicate with the micro-channel region of the chamber of the evaporator  20 . As heat from the CPU is applied to the evaporator  20 , the working fluid contained in the evaporator  20  evaporates into vapor after absorbing the heat. The generated vapor is gathered in the vapor-gathering region of the chamber of the evaporator  20  and then flows, via the first pipe sections  31  of the conduits  30 , to the second pipe sections  33  of the conduits  30  where the vapor releases its latent heat of evaporation to the metal fins of the condenser  50 . After the vapor releases the heat at the condenser  50 , it turns into condensate. The condensate then returns back to the evaporator  20  where it is again available for evaporation, thus forming a heat transfer loop. Specifically, the condensate is drawn back to the evaporator  20  under the capillary forces developed by the wick structures provided in the conduits  30  and the wick structure  20   c  provided in the evaporator  20 . In the heat exchange device  10 , since the micro-channel region of the evaporator  20  is filled with the wick structure  20   c,  the generated vapor in the evaporator  20  is thus prevented from moving backwards and proceeding along the second pipe sections  33  of the conduits  30 ; thus, the unidirectional working fluid movement mechanism along the heat transfer loop of the heat exchange device  10  is maintained. In order to prevent the vapor from being cooled prematurely as it flows along the first pipe sections  31  of the conduits  30 , the first pipe sections  31  may be maintained not to thermally contact with the metal fins of the condenser  50 .  
         [0022]     Referring back to  FIG. 2 , the mounting plate  100  has a heat sink  22  formed at a middle portion thereof. The heat sink  22  is integrally formed with the mounting plate  100 . Four mounting holes  102  are defined at corners of the mounting plate  100 , respectively. With reference also to  FIG. 6 , each of the fastening pins  110  has a pair of opposite barbs  112  extending outwardly and downwardly from a tip end thereof. In order to increase the resiliency of the barbs  112 , a groove  116  is defined in each of the barbs  112 .  
         [0023]     The heat sink  22  formed on the mounting plate  100  is maintained in intimate thermal contact with the top cover  20   a  of the evaporator  20  and is aligned with the wick structure  20   c  contained in the evaporator  20 , as shown in  FIGS. 4-5 . The heat sink  22  has a footprint sufficiently to cover the wick structure  20   c  but smaller than the top cover  20   a  of the evaporator  20 . Since the micro-channel region in the evaporator  20  is connected with the adjacent vapor-gathering region, a small portion of the vapor generated in the evaporator  20  will also enter into the micro-channels defined by the wick structure  20   c  and accordingly accumulate in the micro-channel region due to a large vapor pressure of the vapor-gathering region. The heat sink  22  attached to the evaporator  20  is used to condense that portion of vapor accumulated in the micro-channel region, thus maintaining the working fluid to flow in the unidirectional direction along the heat transfer loop of the heat exchange device  10 .  
         [0024]     The fan duct  60 , as shown in more detail in  FIGS. 4-5 , includes a top plate  60   a  and a pair of sidewalls  60   b  depending from opposite sides of the top plate  60   a.  A flange  62  extends outwardly from a bottom edge of each of the sidewalls  60   b,  as shown in  FIG. 5 . A plurality of mounting sleeves  64  is formed on the flange  62 , aligned with the mounting holes  102  of the mounting plate  100 .  
         [0025]     With reference to  FIGS. 2 and 4 - 5 , in assembly, the mounting plate  100  is fixedly placed between the evaporator  20  and the condenser  50 , with the heat sink  22  thermally contacting the evaporator  20 . The air-guiding members  90   a,    90   b  are respectively mounted to top and bottom sides of the condenser  50 . Each of the air-guiding members  90   a,    90   b  has an inclined surface (not labeled) provided near the electric fan  70  whereby an airflow generated by the electric fan  70  is guided to flow towards the condenser  50  and heat sink  22  to enhance heat dissipation effectiveness thereof. The fastening pins  110  extend respectively through the mounting holes  102  of the mounting plate  100  and then engage with the mounting sleeves  64  formed on the flanges  62  of the fan duct  60 , whereby the loop-type heat exchange device  10  is secured within the fan duct  60 . Specifically, each of the mounting sleeves  64  of the fan duct  60  defines a pair of opposite cutouts  64 a corresponding to the barbs  112  of each of the fastening pins  110 , as particularly shown in  FIG. 5 . The barbs  112  of the fastening pins  110  are deflected as the fastening pins  110  are inserted into the mounting sleeves  64 . Then, the barbs  112  restore back to their original shapes and engage with the mounting sleeves  64  in the cutouts  64   a.  The electric fan  70  is secured to one side of the fan duct  60  for providing forced convection for the heat exchange device  10 . After the heat exchange device  10  is secured within the fan duct  60 , the second pipe sections  33  of the conduits  30  are located nearer to the electric fan  70  than the first pipe sections  31  of the conduits  30  in order to facilitate the heat exchange between the condenser  50  and the second pipe sections  33  of the conduits  30  as the vapor flows through the second pipe sections  33 .  
         [0026]     The heat sink  22  used to cool the micro-channel region of the evaporator  20  may also be formed independently of the mounting plate  100 . As shown in  FIG. 7 , the heat sink  22   a  after being made is attached to the mounting plate  100   a  by gluing or otherwise adhesively attached to the mounting plate  100   a.  As a further example shown in  FIG. 8 , the heat sink  22   b  is captured within an aperture (not labeled) defined in the mounting plate  100   b  and is directly attached to the top cover  20   a  of the evaporator  20 .  
         [0027]     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.