Abstract:
A heat exchange module ( 1 ) includes a fan duct, an evaporator ( 22 ), a condenser ( 26 ) and an electric fan ( 50 ). The fan duct includes a lower portion ( 10 ) and an upper portion ( 30 ). The lower portion cooperates with the upper portion to define therebetween an air passage ( 90 ). The evaporator contains therein a working fluid. The condenser is in fluid communication with the evaporator. The evaporator and the condenser are received in the air passage defined by the fan duct. The working fluid turns into vapor in the evaporator upon receiving heat from a heat-generating component ( 70 ) and the vapor turns into condensate upon releasing the heat to the condenser. The electric fan is attached to the fan duct. The electric fan produces an airflow flowing through the air passage for removing the heat away from the condenser.

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to an apparatus for dissipation of heat from heat-generating components, and more particularly to a heat exchange module suitable for removing heat from heat-generating electronic components. 
   DESCRIPTION OF RELATED ART 
   As progress continues developing in electronic industries, electronic components such as integrated circuit chips of computers are made 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, which in turn will adversely affect their workability and stability. It is well known that heat dissipating devices are commonly used to remove heat from heat-generating components. However, currently well-known heat dissipating devices such as heat sinks plus electric fans are no longer qualified or desirable for removing the heat from these electronic components due to their low heat removal capacity. Conventionally, increasing the rotation speed of the electric fan and increasing the size of the heat sink are two approaches commonly used to improve the heat dissipating performance of the heat dissipating device involved. However, if the rotation speed of the electric fan is increased, problems such as large noise will inevitably be raised. On the other hand, by increasing the size of the heat sink, it will make the heat dissipating device bulky, which contravenes the current trend towards miniaturization. 
   Currently, a loop-type heat exchange device with a more efficient heat dissipating effect has been proposed, which generally includes an evaporator and a condenser. The evaporator contains therein a working fluid. The working fluid in the evaporator evaporates into vapor after absorbing heat from a heat source, and the generated vapor is transferred to the condenser where the vapor is condensed into condensate after the vapor releases the heat. The condensate in the condenser is then transferred back to the evaporator for being available again for evaporation, thus forming a heat transfer loop for continuously taking heat away from the heat source. 
   When the foregoing heat exchange device is mounted to, for example, a computer system for dissipating heat from a heat generating electronic component thereof, the evaporator and the condenser often are required to be mounted individually. It is a time-consuming and tiresome job to do so. Sometimes, it is also desirable to detach the heat exchange device from the computer system for repair or replacement. In this situation, the evaporator and the condenser must also be individually addressed so as to remove the heat exchange device from the computer system. 
   Therefore, it is desirable to provide a highly efficient heat dissipating device which overcomes the foregoing disadvantages. 
   SUMMARY OF INVENTION 
   The present invention relates to a heat exchange module for removing heat from a heat-generating component. The heat exchange module includes a fan duct, an evaporator, a condenser and an electric fan. The fan duct includes a lower portion and an upper portion. The lower portion cooperates with the upper portion to define therebetween an air passage. The evaporator contains therein a working fluid. The condenser is in fluid communication with the evaporator. The evaporator and the condenser are received in the air passage defined by the fan duct. The working fluid turns into vapor in the evaporator upon receiving heat from the heat-generating component and the vapor turns into condensate upon releasing the heat to the condenser. The electric fan is attached to the fan duct. The electric fan produces an airflow flowing through the air passage for removing the heat away from the condenser. 
   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 a partially sectioned, isometric view of a heat exchange module in accordance with one embodiment of the present invention; 
       FIG. 2  is an exploded, isometric view of the heat exchange module of  FIG. 1 ; 
       FIG. 3  is an exploded, isometric view of a loop-type heat exchange device and a mounting base of the heat exchange module of  FIG. 1 ; 
       FIG. 4  is a cross-sectional view of an evaporator of the loop-type heat exchange device of  FIG. 3 , taken along line IV-IV thereof; 
       FIG. 5  is an isometric view of the evaporator of  FIG. 3 , with a top cover thereof being removed; 
       FIG. 6  is a cross-sectional view of a condenser of the loop-type heat exchange device of  FIG. 3 , taken along line VI-VI thereof; 
       FIG. 7  is similar to  FIG. 3 , showing a loop-type heat exchange device in accordance with another example, the heat exchange device being mounted on the mounting base; 
       FIG. 8  is a partially sectioned, isometric view of a fan duct of the heat exchange module of  FIG. 1  in an upside down manner; 
       FIG. 9  is an isometric view showing the heat exchange module of  FIG. 1  being assembled to a computer system; and 
       FIG. 10  is a side elevational view of the assembly of  FIG. 9 . 
   

   DETAILED DESCRIPTION 
     FIGS. 1-2  illustrate a heat exchange module  1  in accordance with one embodiment of the present invention. The heat exchange module  1  includes a mounting base  10 , a loop-type heat exchange device  20 , an air-guiding member  30  and an electric fan  50 . The heat exchange device  20  is mounted on the mounting base  10  and located within the air-guiding member  30 . The exchange device  20  includes an evaporator  22 , a vapor conduit  24 , a condenser  26  and a liquid conduit  28 . Two ends of each of the vapor and liquid conduits  24 ,  28  are connected to the evaporator  22  and the condenser  26 , respectively. The air-guiding member  30  is mounted to the mounting base  10  by a plurality of fasteners  60 . The electric fan  50  is attached by a plurality of screws (not labeled) to one longitudinal side of the air-guiding member  30  to which the condenser  26  of the heat exchange device  20  is adjacent. The heat exchange module  1  as a whole is attached to a heat-generating component such a central processing unit (CPU)  70  of a computer system for dissipating heat from the CPU  70 , as illustrated in  FIG. 10 . In this embodiment, the heat exchange module  1  is attached to the CPU  70  by a plurality of screws  80 , as shown in  FIGS. 2 and 10 . 
   As shown in  FIG. 3 , the mounting base  10  has a substantially rectangular, plate-like configuration. The mounting base  10  defines a through hole  12  therein and four mounting holes  14  around the through hole  12  of the mounting base  10 . 
   With reference to  FIGS. 4-5 , the evaporator  22  has a plate-type configuration including a top cover  221  and a bottom cover  222 . The top and bottom covers  221 ,  222  cooperate with each other to define a chamber  223  inside the evaporator  22 . The bottom cover  222  includes a first, thicker section  222   a  and a second, thinner section  222   b  integrally extending from one side of the first section  222   a . The first section  222   a  projects downwardly to an extent below the second section  222   b  with a step (not labeled) formed between the first and second sections  222   a ,  222   b . A protrusion  225  is formed by extending further downwardly from a substantially middle portion of the first section  222   a  of the bottom cover  222  for passing through the through hole  12  of the mounting base  10  to contact with the CPU  70 . A first wick structure  226  is arranged inside the evaporator  22  and saturated with a working fluid (not shown) such as water or alcohol. The first wick structure  226  is preferably in the form of sintered powders or a screen mesh made of flexible metal wires or organic fibers woven together. 
   The chamber  223  of the evaporator  22  includes two major regions, i.e., an evaporating region  223   a  and an adjacent liquid micro-channel region  223   b , corresponding to the first and second sections  222   a ,  222   b  of the bottom cover  222  of the evaporator  22 , respectively. The micro-channel region  223   b  is fully filled with the first wick structure  226 . Also, a portion of the first wick structure  226  extends from the micro-channel region  223   b  into a middle part of the evaporating region  223   a . This portion of the first wick structure  226  has a size substantially equal to that of the protrusion  225  of the bottom cover  222 , and is fittingly located just above and covers the protrusion  225 . Additionally, another portion of the first wick structure  226  also extends from the micro-channel region  223   b  into front and rear sides of the evaporating region  223   a , as viewed from  FIG. 5 . As a result, the first wick structure  226  spans across both the micro-channel region  223   b  and the evaporating region  223   a . The remaining part of the evaporating region  223   a  not filled with the first wick structure  226  is provided as a vapor-gathering sub-region  223   c  for accommodating the generated vapor in the evaporator  22 . The vapor and liquid conduits  24 ,  28  are connected to the evaporating region  223   a  and the micro-channel region  223   b , respectively. Specifically, the vapor conduit  24  communicates with the vapor-gathering sub-region  223   c  so as to enable the vapor gathered in the vapor-gathering sub-region  223   c  to leave the evaporator  22  into the vapor conduit  24 . As particularly shown in  FIG. 4 , a plurality of metal fins  228  extends from an outer surface of each of the top and bottom covers  221 ,  222 , aligned with the micro-channel region  223   b.    
   In order to bring the condensate from the condenser  26  back to the evaporator  22  timely, a second wick structure  281  is provided inside the liquid conduit  28 , as particularly shown in  FIG. 5 . The second wick structure  281  may be fine grooves integrally formed at the inner surface of the liquid conduit  28 , screen mesh or bundles of fiber inserted into the liquid conduit  28 , or sintered powders combined to the inner surface of the liquid conduit  28 . 
   Referring now to  FIG. 6 , the condenser  26  includes top and bottom housings  261 ,  262  and a plurality of condensing tubes  263  along which a plurality of metal fins  264  is stacked. Each of the top and bottom housings  261 ,  262  has an elongated, box-like structure. These condensing tubes  263  are located between the top and bottom housings  261 ,  262  and are positioned in parallel with each other. Two ends of each of these condensing tubes  263  are communicated with the top and bottom housings  261 ,  262 , respectively. Specifically, a bottom wall  261   a  of the top housing  261  and a top wall  262   a  of the bottom housing  262  each define therein a plurality of holes (not labeled). Top and bottom ends of these condensing tubes  263  are fixedly and hermetically positioned in these holes defined in the walls  261   a ,  262   a . As presenting a large heat dissipating surface area, the metal fins  264  are made of highly thermally conductive material such as copper or aluminum and are maintained in intimate thermal contact with a circumferential surface of each of the condensing tubes  263 . The bottom housing  262  has an inlet  266  and an outlet  267  for being connected to the vapor and liquid conduits  24 ,  28 , respectively. As shown in  FIGS. 1-3 , the condenser  26  is positioned in an upright position with the condensing tubes  263  being located perpendicularly to the liquid conduit  28 . 
   As heat from the CPU  70  is applied to the evaporator  22 , the working fluid contained in the evaporator  22  evaporates into vapor after absorbing the heat. Then, the generated vapor flows, via the vapor conduit  24 , to the condenser  26  where the vapor releases its latent heat of evaporation and accordingly turns into condensate. The vapor conduit  24  may also have a larger diameter than the liquid conduit  28  so as to enable the generated vapor in the evaporator  22  to move towards the condenser  26  smoothly. Specifically, the heat generated by the CPU  70  is firstly transferred to the first section  222   a  of the bottom cover  222  and then to the evaporating region  223   a  of the chamber  223  to cause the working fluid contained in that region to evaporate into the vapor. Due to the difference of vapor pressure between the evaporator  22  and the condenser  26 , the generated vapor moves towards the condenser  26 . As the vapor enters into the bottom housing  262  of the condenser  26  through the inlet  266 , the vapor moves freely into the condensing tubes  263  where the vapor releases the heat carried thereby to the metal fins  264  contacting the condensing tubes  263 . The heat further is dissipated into ambient environment by the condenser  26  in combination with the electric fan  50 . With these condensing tubes  263  and metal fins  264 , the condenser  26  has a large heat removal capacity and therefore the vapor can be effectively cooled at the condenser  26 . 
   In order to prevent the vapor transferred by the vapor conduit  24  from being prematurely condensed in the vapor conduit  24  due to the cooling of the airflow of the electric fan  50 , the vapor conduit  30  is preferably made of heat insulating material. Due to gravity, the condensate resulted from the vapor in the condensing tubes  263  flows towards the bottom housing  262 . Thereafter, the condensate gathered in the bottom housing  262  flows through the outlet  267  into the liquid conduit  28  through which the condensate is brought back to the evaporator  22  where it is again available for evaporation. In order to enable the condensate contained in the bottom housing  262  to enter into the liquid conduit  28  more rapidly and smoothly, the bottom housing  262  has a slanted inner bottom surface  268  declining from the inlet  266  towards the outlet  267 . The bottom surface  268  has a lowest level around the outlet  267 . On the other hand, in order to prevent the vapor in the bottom housing  262  from directly entering into the liquid conduit  28  through the outlet  267  without having been condensed in the condenser  26 , a baffle  269  is provided above the outlet  267  and arranged in such a manner that it blocks a vast majority of the vapor in the bottom housing  262  to directly enter into the liquid conduit  28  but does not block the condensate in the bottom housing  262  to enter into the liquid conduit  28 . After the working fluid in the evaporating region  223   a  is evaporated, an inventory of the working fluid in the evaporating region  223   a  is reduced due to the evaporation in that region. The condensate returned to the micro-channel region  223   b  is subsequently supplied to the evaporating region  223   a  for being available again for evaporation as a result of the capillary force of the first wick structure  226 . This cycle of the working fluid effectively takes heat away from the CPU  70 . 
   In the heat exchange device  20 , the movement of the working fluid forms a heat transfer loop whereby the heat of the CPU  70  is effectively removed away. The movements of the vapor and the condensate in the heat exchange device  20  are carried out separately in the respective vapor and liquid conduits  24 ,  28 . The condensate is drawn back to the evaporator  22  under the capillary forces of the second and first wick structures  281 ,  226  as respectively provided in the liquid conduit  28  and the evaporator  22 , thereby preventing an excessive amount of the condensate from accumulating in the condenser  26  and meanwhile avoiding the potential dry-out problem occurring at the evaporator  22 . 
     FIG. 7  shows an alternative embodiment of the present heat exchange device  10 . In this embodiment, the vapor and liquid conduits  24 ,  28  are connected to the top and bottom housings  261 ,  262  of the condenser  26 , respectively. Since the vapor transferred by the vapor conduit  24  enters into the condenser  26  from the top housing  261 , the baffle  269  as provided in the bottom housing  262  as shown in  FIG. 6  is no longer required. 
   In the present heat exchange device  20 , the two-section design of the bottom cover  222  with different thicknesses is aimed to reduce an amount of the heat of the CPU to be conducted from the first section  222   a  to the second section  222   b  and finally to the micro-channel region  223   b  of the evaporator  22 . Since the first section  222   a  has a larger thickness than the second section  222   b , the heat conducted laterally from the first section  222   a  towards the second section  222   b  is reduced in comparison with a bottom cover with a uniform thickness. Accordingly, the heat transferred to the micro-channel region  223   b  of the evaporator  22  from the bottom cover  222  is also effectively reduced, the condensate in the micro-channel region  223   b  is less likely to be heated directly in that region, and excessive vapor is thus prevented from being formed and accumulated in the micro-channel region  223   b.    
   The metal fins  228  of the evaporator  22  are provided as a cooling device to lower down the temperature of the micro-channel region  223   b  and at the same time to prevent vapor from being formed and accumulated in that region. Since the micro-channel region  223   b  is connected with the adjacent evaporating region  223   a , a portion of the vapor generated in the evaporating region  223   a  will “creep” from the evaporating region  223   a  into the micro-channel region  223   b  due to a large vapor pressure in the vapor-gathering sub-region  223   c . Additionally, the temperature in the micro-channel region  223   b  will also gradually increase, subject to a relatively high temperature and a flow of the vapor in the evaporating region  223   a . The metal fins  228  are applied to directly condense the vapor entering into the micro-channel region  223   b  and meanwhile to dissipate the heat transferred to the micro-channel region  223   b  from the adjacent evaporating region  223   a  or the second, thinner section  222   b  of the bottom cover  222 . Thus, due to the presence of the metal fins  228 , the vapor potentially to be formed and accumulated in the micro-channel region  223   b  is greatly reduced. 
   The air-guiding member  30 , as shown in more detail in  FIG. 8 , has an inverted U-shaped configuration and includes a top plate  30   a  and a pair of sidewalls  30   b  depending from opposite sides of the top plate  30   a . A flange  32  extends outwardly from a bottom edge of each of the sidewalls  30   b . A pair of mounting sleeves  34 , as being spaced from each other, is formed on the flange  32 . Each of the flanges  32  has a arced projection  36  formed thereon. The arced projection  36  projects downwardly and is located between the mounting sleeves  34  formed on each flange  32 . Each of the mounting sleeves  34  of the air-guiding member  30  defines a pair of opposite cutouts  34   a . With reference also to  FIG. 2 , the mounting sleeves  34  are aligned with the mounting holes  14  of the mounting base  10 . Each of the fasteners  60  has a pair of elastic barbs  62  extending outwardly and downwardly from opposite sides of a tip end thereof, corresponding to the cutouts  34   a  of each of the mounting sleeves  34 . 
   With reference to  FIGS. 1-3  and  9 - 10 , in assembly, the evaporator  22  of the heat exchange device  20  is mounted to the mounting base  10 . The protrusion  225  of the evaporator  22  is received in the through hole  12  of the mounting base  10  and projects below an underside of the mounting base  10  in order for contacting with the CPU  70 . The fasteners  60  respectively extend through the mounting holes  14  of the mounting base  10  and extend into the mounting sleeves  34  of the air-guiding member  30 . The barbs  62  of the fasteners  60  are brought into engagement with the mounting sleeves  34  in the cutouts  64   a  whereby the air-guiding member  30  is mounted to the mounting base  10 . At this position, the arced protrusions  36  of the air-guiding member  30  are also brought into abutment with the mounting base  10 . Due to the presence of the protrusions  36 , the mounting base  10  is capable of being rotated with respect to the air-guiding member  30  around the two protrusions  36  within a small angle of rotation so as to perfectly maintain the protrusion  225  of the evaporator  22  to have a coplanar contact with the entire top surface of the CPU  70  as the heat exchange module  1  is mounted to the CPU  70  for dissipating heat therefrom. The electric fan  50  is attached to the air-guiding member  30  and located adjacent to the condenser  26 . The electric fan  50  has a footprint larger than that of the condenser  26  and a bottom portion of the electric fan  50  extends below the mounting base  10 , as particularly shown in  FIG. 1 . The air-guiding member  30  cooperates with the mounting base  10  to form a fan duct with an air passage  90  being formed in the fan duct for passage of the airflow of the electric fan  50 , as shown in  FIG. 9 . The heat exchange device  20  is received in the air passage  90  of the air duct. The airflow of the electric fan  50  is guidable from one end of the air passage where the condenser  26  is located to the other end thereof. 
   After being previously assembled, the heat exchange module  1  can be subsequently mounted to the CPU  70  of the computer system easily by the screws  80  extending respectively through holes (not labeled) defined in the flanges  32  of the air-guiding member  30  and finally secured to a printed circuit board (PCB)  100  on which the CPU  70  is mounted or a system casing  110  of the computer system, which is mounted under the PCB  100 . The protrusion  225  of the evaporator  22  is maintained in thermal contact with the CPU  70 . The mounting base  10  is spaced from the PCB  100  by a specific distance, which is substantially the same as a length of that portion of the electric fan  50  that extends below the mounting base  10 , as shown in  FIG. 10 . The airflow produced by the electric fan  50  is capable of being divided into two currents, one current flowing through the air passage  90  for cooling the condenser  26  of the heat exchange device  20 , the other current flowing from beneath the mounting base  10  for simultaneously cooling the CPU  70 , the evaporator  22  of the heat exchange device  20  and the mounting base  10 . Under the guidance of the fan duct, the airflow of the electric fan  50 , after flowing through the air passage  90 , is still capable of being used to cool other heat-generating electronic components  101  located near the heat exchange module  1  and which are also mounted on the PCB  100 . In the present heat exchange module  1 , the mounting base  10  is made of high thermally conductive material such as copper or aluminum in order to facilitate heat dissipation from the CPU  70 . However, the mounting base  10  may also be made of plastic material in order to lower down the manufacturing cost thereof. 
   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.