Patent Publication Number: US-2009236078-A1

Title: Heat-dissipating device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority of Taiwanese application no. 097109858, filed on Mar. 20, 2008. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a heat-dissipating device, more particularly to a heat-dissipating device for dissipating heat individually from a plurality of heat sources so as to ensure uniform heat dissipation thereamong. 
     2. Description of the Related Art 
     As shown in FIGS. 1 and 2, Taiwanese Utility Model Patent No. M326999 discloses a heat-dissipating device 1 for dissipating heat from a light-emitting unit 2 which includes a plurality of light-emitting diodes (LEDs) (21a) to (21d). The heat-dissipating device 1 includes a base 11, and the light-emitting unit 2 is mounted on the base 11 in an array configuration of a plurality of columns of the LEDs (21a) to (21d). The heat-dissipating device 1 further includes a plurality of fins 12 mounted on the base 11 and stacked in a parallel manner, and a plurality of heat pipes 13 each channeling through the fins 12. Each heat pipe 13 is U-shaped and has an absorbing section 131 that is in proximity to the light-emitting unit 2, and a cooling section 132 that is distal from the absorbing section 131. 
     During operation of the light-emitting unit 2, working fluid contained in each heat pipe 13 absorbs heat from the LEDs (21a) to (21d), eventually causing the working fluid to vaporize into its gaseous phase. The vaporized working fluid travels toward the cooling section 132 where it condenses back to its liquid phase due to the cooler temperature at the cooling section 132. Consequently, the working fluid performs a heat-exchange function. 
     However, a drawback of this configuration is that the heat from the LEDs (21a) to (21d) of each column thereof is not uniformly dissipated. For instance, the arrows shown in FIG. 2 indicate how the working fluid travels back to the absorbing section 131 after it is condensed in the cooling section 132. As a result, the LED (21a) will experience heat dissipation first from the condensed (i.e., re-cooled) working fluid before the LED (21b), and the LED (21b) before the LED (21c), and so on. A significant drawback of this conventional heat-dissipating device is that the working fluid may be too hot by the time it reaches the last LED (21d). As a consequence, the working fluid becomes less effective for reducing the temperature of the LED (21d). Ultimately, this leads to a reduction in the illumination uniformity of the light-emitting unit 2. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a heat-dissipating device that can overcome the above drawbacks of the prior art. 
     According to the present invention, a heat-dissipating device is used for dissipating heat from a plurality of heat sources. The heat-dissipating device includes a plurality of elongated thermally conductive elements each having an end adapted to thermally contact a respective one of the heat sources, and a fin structure connected to the thermally conductive elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which: 
         FIG. 1  is a perspective view of a conventional heat-dissipating device in a state associated with a light-emitting unit; 
         FIG. 2  is a cross-sectional view of the heat-dissipating device shown in  FIG. 1 , illustrating the directional flow of a working fluid after the working fluid condenses; 
         FIG. 3  is an exploded perspective view of the first preferred embodiment of a heat-dissipating device according to the present invention; 
         FIG. 4  is an assembled perspective view of the first preferred embodiment; 
         FIG. 5  is a sectional view of the first preferred embodiment; 
         FIG. 6  is a sectional view of a modified example of the first preferred embodiment of the heat-dissipating device in accordance with the present invention; 
         FIG. 7  is a sectional view of a heat-dissipating device in accordance with the second preferred embodiment of the present invention; 
         FIG. 8  is a sectional view of a heat-dissipating device in accordance with the third preferred embodiment of the present invention; and 
         FIG. 9  is a sectional view of a heat-dissipating device in accordance with the fourth preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Before the present invention is described in greater detail, it should be noted that like elements are denoted by the same reference numerals throughout the disclosure. 
     Referring to  FIGS. 3 ,  4 , and  5 , the first preferred embodiment of a heat-dissipating device according to the present invention is used to dissipate heat from a plurality of heat sources  31 . The heat-dissipating device includes a plurality of elongated thermally conductive elements  4  each having a first end  41  adapted to thermally contact a respective one of the heat sources  31  and a second end  42  opposite to the first end  41 . The heat-dissipating device further includes a fin structure  5  connected to the thermally conductive elements  4 . The thermally conductive elements  4  pass through the fin structure  5 . 
     Preferably, the fin structure  5  includes a plurality of spaced-apart plate-shaped fins that are parallel to each other. In this embodiment, the heat sources  31  are light-emitting diodes (LEDs), and each thermally conductive element  4  is hollow to thereby define a hollow chamber  40  that is filled with a working fluid. The working fluid may be a liquid coolant. 
     In use, when each heat source  31  illuminates, the working fluid contained in the respective one of the thermally conductive elements  4  absorbs heat from the heat source  31  via the first end  41  of the thermally conductive element  4 . As the temperature of the working fluid rises, the working fluid gradually vaporizes into its hot gaseous phase. The vaporized working fluid travels toward the second end  42  of the thermally conductive element  4  where it condenses back to its liquid phase due to the cooler temperature at the second end  42 . The condensed working fluid returns to the first end  41  and the process repeats. As a result, the working fluid performs a heat-exchange function. By employing this design, each heat source  31  can have its own working fluid for heat dissipation so that the heat dissipation for all of the heat sources  31  is made uniform. 
       FIG. 6  illustrates a modified example of the first preferred embodiment of this invention in which each of the thermally conductive elements  4  is formed in a dual-chambered configuration. 
       FIG. 7  illustrates a second preferred embodiment of this invention, which differs from the first preferred embodiment in that the heat-dissipating device further includes a fan  6 . In this embodiment, the fan  6  is disposed in proximity to the fin structure  5  so as to direct air thereonto. The fan  6  continuously blows air towards the fin structure  5  in order to enhance the transfer of thermal energy from the fin structure  5  to the surrounding air. 
       FIG. 8  illustrates a third preferred embodiment of this invention, which differs from the first preferred embodiment in that each of the thermally conductive elements  4  is U-shaped and hollow. Hence, the working fluid is not filled in the thermally conductive elements  4  in this embodiment. 
       FIG. 9  illustrates a fourth preferred embodiment of this invention, which differs from the first preferred embodiment in that each of the thermally conductive elements  4  is solid and rod-shaped. Hence, the working fluid is also not included in this embodiment. 
     In summary, the heat-dissipating device according to the present invention achieves the advantage of uniformly dissipating heat from a plurality of the heat sources  31 . 
     While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.