Abstract:
A cooling device for dissipating heat for an electronic device includes a shell to absorb heat generating from a heat generating element in the electronic device, and a number of fins. The shell bounds a heat exchanging space and defines an air intake and an air outlet. The number of fins extends into the heat exchanging space. The shell guides air outside the shell to enter into the shell through the air intake and to exit from the shell through the air outlet after exchanging heat in the heat exchanging space.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is related to a copending U.S. patent application, titled “HEAT DISSIPATION STRUCTURE”, with the application Ser. No. 12/436,763, assigned to the same assignee as the present application, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The disclosure relates to a cooling device for electronic devices. 
     2. Description of Related Art 
     Nowadays, the trend for electronic devices, especially computers, is miniaturization, which leads to cooling problems. For example, when cooling a heat generating element, such as a central processing unit, of a notebook computer or a mini desktop computer, two ways are usually used. One way is to employ a traditional fan and heat sink for dissipating heat, which is low-cost but takes up a lot of space. The other way is to employ heat pipes, which are sufficient for cooling, but too expensive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of a first exemplary embodiment of a cooling device. 
         FIG. 2  is a cross-sectional, exploded view of the cooling device in  FIG. 1  and an electronic device. 
         FIG. 3  is an assembled view of the cooling device and the electronic device of  FIG. 2 . 
         FIG. 4  is an isometric view of a second exemplary embodiment of a cooling device. 
         FIG. 5  is a cross-sectional, exploded view of the cooling device in  FIG. 4  and an electronic device. 
         FIG. 6  is an assembled view of the cooling device and the electronic device of  FIG. 5 . 
         FIG. 7  is an isometric view of a third exemplary embodiment of a cooling device. 
         FIG. 8  is a cross-sectional, assembled view of the cooling device in  FIG. 7  and an electronic device. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 to 3 , a cooling device  10  according to a first embodiment of the present disclosure is used for cooling a first heat generating element  61  of an electronic device  70 . 
     The electronic device  70  includes a housing  50  and a printed circuit board (PCB)  60  mounted in the housing  50 . A depressed portion  51  is formed in the housing  50 . An opening  52  is defined in a center of a bottom wall  55  of the depressed portion  51 . The PCB  60  includes a first heat generating element  61  and a plurality of second heat generating elements  63 . In one embodiment, the electronic device  70  is a computer, the PCB  60  is a motherboard, and the first heat generating element  61  is a central processing unit (CPU). 
     The cooling device  10  includes a generally short cylinder-shaped shell  20 , matching the opening  52  of the housing  50  of the electronic device  70 . The shell  20  defines a heat exchanging space  26  therein and includes a top board  22 , a bottom board  30 , and an annular side board  24  perpendicularly connected between edges of the top board  22  and the bottom board  30 . The top board  22 , the bottom board  30 , and the side board  24  bound the heat exchanging space  26 . A hole is defined in a center of the top board  22 , forming an air intake  21 . A plurality of slots is spacedly defined in the side board  24 , adjacent to the bottom board  30  to form an air outlet  23 . The bottom board  30  touches the first heat generating element  61  to collect heat generated by the heat generating element  61 . A plurality of fins  31  extends perpendicularly from the inner side of the bottom board  30  in the shell  20 , and radially extends from a center of the shell  20  to the air outlet  23 . An eddy current fan  40  is mounted in the shell  20 , encircled by the plurality of fins  31 . 
     In assembly, the cooling device  10  is mounted to the electronic device  70  via the opening  52  of the depressed portion  51  of the housing  50 . The bottom board  30  of the cooling device  10  abuts against the first heat generating element  61  in the housing  50 . The air intake  21  and the air outlet  23  of the cooling device  10  are located outside the housing  50 . 
     In use, the bottom board  30  of the cooling device  10  collects heat generating from the first heat generating element  61  and transfers the heat to the plurality of fins  31 . When the fan  40  works, it draws air from outside the housing  50  into the cooling device  10  through the air intake  21 . The air then exits from the cooling device  10  through the air outlet  23 , taking heat of the plurality of fins  31  directly to the outside of the housing  50  of the electronic device  70 . 
     It is noted that the depressed portion  51  of the housing  50  is designed for reducing overall thickness and beautifying the external appearance of the electronic device  70  mounting the cooling device  10 . 
     In other embodiments, a blade fan may be used to replace the eddy current fan  40 . 
     Referring to  FIGS. 4 to 6 , a cooling device  10 A according to a second embodiment of the present disclosure is used for cooling a first heat generating element  61 A of an electronic device  70 A. 
     The electronic device  70 A includes a housing  50 A and a printed circuit board (PCB)  60 A mounted in the housing  50 A. An opening  52 A is defined in the housing  50 A. The PCB  60 A includes a first heat generating element  61 A and a plurality of second heat generating elements  63 A. 
     The cooling device  10 A includes a shell  20 A, matching the opening  52 A of the housing  50 A of the electronic device  70 A. The shell  20 A defines a heat exchanging space  26 A therein and includes a generally tapered top board  22 A, a bottom board  30 A, and an annular side board  24 A connected between edges of the top board  22 A and the bottom board  30 A. The top board  22 A, the bottom board  30 A, and the side board  24 A bound the heat exchanging space  26 A. A hole is defined in a first side of the top board  22 A, forming an air intake  21 A. A fan-shaped hole is defined in a second side of the top board  22 A opposite to the first side, forming an air outlet  23 A. The bottom board  30 A touches the first heat generating element  61 A to collect heat generated by the heat generating element  61 A. A plurality of fins  31 A in a fan-like arrangement extends perpendicularly from an inner side of the bottom board  30 A to the air outlet  23 A. A blade fan  40 A is mounted in the air intake  21 A of the shell  20 A. 
     In assembly, the cooling device  10 A is mounted to the electronic device  70 A via the opening  52 A of the housing  50 A. The bottom board  30 A of the cooling device  10 A abuts against the first heat generating element  61 A in the housing  50 A. The air intake  21 A and the air outlet  23 A of the cooling device  10 A are located outside the housing  50 A. 
     In use, the bottom board  30 A of the cooling device  10 A collects heat from the first heat generating element  61 A and transfers the heat to the plurality of fins  31 A. When the fan  40 A works, it draws air from outside the housing  50 A into the cooling device  10 A through the air intake  21 A, and then the air exits from the cooling device  10 A through the air outlet  23 A, taking heat of the plurality of fins  31 A, directly to the outside of the housing  50 A of the electronic device  70 A. 
     In other embodiments, an eddy current fan may be used to replace the blade fan  40 A. 
     According to the first and second embodiments, a direct thermal through technology (DTT) is used for the cooling device  10  or  10 A to cool the first heat generating element  61  or  61 A. In other words, because of the use of the DTT, the cool air does not merely pass through the inside of the housing  50  or  50 A, but directly enters into the cooling device  10  or  10 A from the outside of the housing  50  or  50 A, passes through the cooling device  10  or  10 A, and then directly exits to the outside of the housing  50  or  50 A. The air intake  21  or  21 A and the corresponding air outlet  23  or  23 A of the corresponding cooling device  10  or  10 A are both located outside the corresponding housing  50  or  50 A, thereby avoiding heated air to tarry in the corresponding electronic device  70  or  70 A so as to improve heat radiating efficiency. 
     Referring to  FIGS. 7 and 8 , a cooling device  10 B according to a third embodiment of the present disclosure is shown, differing from the second embodiment in  FIGS. 4 to 6  only in that a plurality of valves  25 B is employed. The plurality of valves  25 B is formed on a side board  24 B of a shell  20 B of the cooling device  10 B, inside a housing  50 B of an electronic device  70 B. Each valve  25 B can be controlled to open or close, and an opening degree of the valve  25 B can also be adjusted, allowing superfluous air entering into the housing  50 B to cool one or more second heat generating elements  63 B. 
     The cooling devices  10 ,  10 A, and  10 B of the present disclosure is designed according to the DDT, and provides better than a 50% heat exchange rate thus achieving low cost cooling. The cooling devices  10 ,  10 A, and  10 B can be applied to many electronic devices, especially tiny or slim systems, such as notebook computers, mini desktop computers, or liquid crystal displays. 
     It is to be understood, however, that even though numerous characteristics and advantages of the disclosure 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 details, 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.