Patent Publication Number: US-2017363367-A1

Title: Heat dissipation device

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to heat dissipation techniques and more particularly to a heat dissipation device incorporating a heat spreader and a heat pipe. 
     2. Description of Related Art 
     With the advancement of technology, and in order to satisfy user needs, many electronic products are designed in pursuit of ever better performance, and because of that, the heat generated by the electronic components inside those products is increasing. To effectively address the issue of high heat, heat spreaders and heat pipes are typically used, both of which feature good thermal conductivity. A heat dissipation device, for instance, may include a combination of a heat spreader and a heat pipe. 
     Taiwan Patent No. M286564 discloses a temperature-uniforming heat dissipator that includes a heat spreader, a plurality of heat pipes, and a fin assembly. The heat spreader has an upper plate, a lower plate, and a cavity formed between the plates. The heat pipes, each having an interior space, are fixed on the upper plate of the heat spreader and are mounted with the fin assembly. The temperature-uniforming heat dissipator is characterized mainly in that the interior spaces of the heat pipes are in communication with the cavity of the heat spreader. 
     As is well known in the art, a heat pipe or heat spreader has capillary structures for guiding the flow of a working fluid to achieve heat circulation, wherein the capillary structures are generally composed of sintered copper powder. In the temperature-uniforming heat dissipator of the afore-cited patent, the lower plate of the heat spreader provides a surface for contact with a heat source, and when the working fluid evaporates into a gaseous state and enters the heat pipes, the heat of the working fluid dissipates outward through the pipe walls and the fins. The temperature-uniforming heat dissipator, therefore, relies on a good working fluid to maintain efficient heat dissipation. Moreover, to ensure that the working fluid flows by capillary action, the heat spreader and the inner wall of each heat pipe of the temperature-uniforming heat dissipator must be provided with uninterrupted capillary structures, so an additional processing step is required to connect the capillary structures at the curved joints between the heat spreader and the heat pipes. This additional step, however, complicates the manufacturing process. Also, capillary structures composed of sintered copper powder cannot effectively transport a working fluid over a long distance. 
     To overcome the aforesaid drawbacks, the applicant believes that the foregoing temperature-uniforming heat dissipator needs improvement in heat conduction. 
     BRIEF SUMMARY OF THE INVENTION 
     In view of the drawbacks of the prior art, the primary objective of the present invention is to provide a heat dissipation device in which a heat spreader and a heat pipe are connected by a fiber bundle, and which is highly efficient in heat dissipation because the fiber bundle can transport a working fluid over a long distance with a high mass flux. 
     The heat dissipation device of the present invention includes a heat spreader, a first capillary material, at least one heat pipe, a second capillary material, at least one fiber bundle, and a working fluid. The heat spreader has a first plate and a second plate, and these two plates are connected to form a receiving space therebetween, wherein the receiving space is defined with a heated area. The first capillary material is provided on either or both of the first plate and the second plate and is located in the heated area. The heat pipe has a cavity in communication with the receiving space. One end of the heat pipe is connected to the heat spreader, and the other end of the heat pipe is located outside the heat spreader and is closed. The second capillary material is provided on the inner wall of the heat pipe. The fiber bundle has an elongated shape. A portion of the fiber bundle is in the receiving space while another portion of the fiber bundle extends into the cavity. The portion of the fiber bundle that is in the receiving space is provided on either or both of the first plate and the second plate and is in contact with the first capillary material. The portion of the fiber bundle that is in the cavity is in contact with the second capillary material on the inner wall of the heat pipe. The working fluid is in the receiving space and the cavity. 
     In the present invention, at least one fiber bundle, which is known to be capable of transporting a working fluid over a long distance with a high mass flux, is connected to both the first capillary material in the heated area and the second capillary material in the cavity to enhance heat dissipation efficiency, allowing the heat dissipation device of the present invention to overcome the drawbacks of the conventional improvements made to heat dissipators, particularly an increase in product size or cost and inconveniences in manufacture and use that result from the only conventional solution of increasing the number, or modifying the structure, of fins, heat pipes, or heat spreaders. 
     Preferably, the location where the heat pipe is provided does not correspond to that of the heated area. 
     The heat dissipation device of the present invention allows the joint between the heat spreader and the heat pipe to be changed in position according to user needs, thereby providing greater convenience in manufacture and use than the prior art. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The technical features of the present invention are detailed below with reference to some preferred embodiments in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of the first preferred embodiment of the present invention; 
         FIG. 2  is a bottom perspective view of the first preferred embodiment of the present invention, with the first plate removed; 
         FIG. 3  is a section view taken long line  3 - 3  in  FIG. 1 ; 
         FIG. 4  is a bottom view of the first preferred embodiment of the present invention, with the first plate removed; 
         FIG. 5  is a bottom view of the second preferred embodiment of the present invention, with the first plate removed; 
         FIG. 6  is a sectional view taken along line  6 - 6  of  FIG. 5 ; 
         FIG. 7  is a bottom perspective view of the third preferred embodiment of the present invention, with the first plate removed; 
         FIG. 8  is a bottom view of the third preferred embodiment of the present invention, with the first plate removed; and 
         FIG. 9  is a sectional view taken along line  9 - 9  in  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1  to  FIG. 4 , the first preferred embodiment of the present invention provides a heat dissipation device  10  composed essentially of a heat spreader  11 , a first capillary material  12 , at least one heat pipe  13 , a second capillary material  14 , at least one fiber bundle  15 , and a working fluid (not shown). 
     The heat spreader  11  has a first plate  111  and a second plate  112 . The first plate  111  and the second plate  112  are connected in a sealing manner to form a receiving space  113  therebetween. The receiving space  113  is defined with a heated area H. The heat spreader  11  is further provided with an exhaust pipe  16 . One end of the exhaust pipe  16  is located in the heat spreader  11  and is in communication with the receiving space  113 . The other end of the exhaust pipe  16  is located outside the heat spreader  11  and is closed. 
     The first capillary material  12  is located in the heated area H. The first capillary material  12  may be provided on the first plate  111 , the second plate  112 , or both plates  111  and  112 . In this embodiment, the first capillary material  12  is provided on the second plate  112  by way of example. Besides, the first capillary material  12  may be composed of sintered copper powder or a woven net. In this embodiment, for instance, the first capillary material  12  is composed of sintered copper powder. 
     There are three heat pipes  13  in this embodiment. Each heat pipe  13  has a cavity  131  in communication with the receiving space  113 . Moreover, each heat pipe  13  has one end connected to the heat spreader  11  and the other end outside the heat spreader  11  and closed. The heat pipes  13  in this embodiment do not correspond in position to the heated area H, but it is totally alright that they do. In addition, the heat pipes  13  are inserted through a fin assembly  17 . 
     The second capillary material  14  is provided on the inner wall of each heat pipe  13  and may be composed of sintered copper powder, a woven net, or a groove. In this embodiment, for example, the second capillary material  14  is composed of sintered copper powder. 
     There are three fiber bundles  15  in this embodiment. The fiber bundles  15  are elongated in shape, are partially located in the receiving space  113 , and partially extend into the cavities  131  of the heat pipes  13 . The portions of the fiber bundles  15  that are in the receiving space  113  may be provided on the first plate  111 , the second plate  112 , or both plates  111  and  112 , and in this embodiment are provided on the second plate  112  for example. These portions of the fiber bundles  15  are in contact with first capillary material  12  in the heated area H. Meanwhile, the portions of the fiber bundles  15  that are in the cavities  131  are in contact with the second capillary material  14  in the heat pipes  13 . 
     The working fluid is in the receiving space  113  and the cavity  131  of each heat pipe  13  and is uniformly contained in the first capillary material  12 , the second capillary material  14 , and the fiber bundles  15 . The working fluid is well known in the art and difficult to show in the drawings and therefore will not be further described herein. 
     Having described the structure of the first preferred embodiment, the present specification continues to explain how the first preferred embodiment is used. 
     To use the heat dissipation device  10 , referring to  FIG. 1  through  FIG. 4 , the heated area H is brought into contact with a heat source (not shown) such that the temperature of the heated area H increases. Due to the rise of temperature, the working fluid contained in the first capillary material  12  evaporates into a gaseous state and permeates the receiving space  113 . The gaseous working fluid then flows from the receiving space  113  to the cavity  131  of each heat pipe  13 . In the meantime, the heat carried by the gaseous working fluid is conducted through the walls of the heat pipes  13  to the fin assembly  17  and dissipates outward. After that, the cooled gaseous working fluid condenses into a liquid state, is contained in the second capillary material  14 , then flows back to the first capillary material  12  in the heated area H through the fiber bundles  15  by capillary action, and is contained in the first capillary material  12  again. The heat circulation mechanism described above enables the heat dissipation device  10  of the present invention to dissipate heat. 
     It can be known from the description of the first preferred embodiment that the fiber bundles  15  in the heat dissipation device  10  are connected to both the first capillary material  12  in the heated area H and the second capillary material  14  in the cavities  131 . Hence, by virtue of the long-distance working fluid transportation ability of the fiber bundles  15  and the high mass flux of the working fluid through the fiber bundles  15 , the heat dissipation device  10  has higher heat conduction efficiency than its prior art counterparts, in particular the aforementioned temperature-uniforming heat dissipator, whose capillary structures are formed by sintered copper powder. 
     The first preferred embodiment also shows that the heat dissipation device  10  of the present invention allows the heat pipes  13  to be connected to whichever part of the heat spreader  11  as needed, thus bringing about greater convenience in manufacture and use. 
       FIG. 5  and  FIG. 6  show the heat dissipation device  20  provided by the second preferred embodiment of the present invention. The second preferred embodiment is generally the same as the first preferred embodiment except that the fiber bundles  25  abut against the first plate  211  and the second plate  212 , and that the first capillary material  22  is provided on the first plate  211 . 
     The heat dissipation device  20  disclosed in the second preferred embodiment is so configured that, with the fiber bundles  25  abutting against the first plate  211  as well as the second plate  212 , a heat source (not shown) to be in contact with the heated area H 2  can be brought into contact with either or both of the first plate  211  and the second plate  212  in the heated area H 2 . The only adjustment to be made is to have the first capillary material  22  in the heated area H 2  correspond in position to the heat source. Since such an adjustment involves no other changes in structure or appearance, the aforesaid structural modification can be implemented with ease. The basic heat dissipation mechanism can be achieved even without the first capillary material  22 , although the presence of the first capillary material  22  leads to higher heat dissipation efficiency. The functions of the other components are the same as those in the first preferred embodiment and therefore will not be described repeatedly. 
       FIG. 7  to  FIG. 9  show the heat dissipation device  30  provided by the third preferred embodiment of the present invention. The third preferred embodiment is generally the same as the first preferred embodiment except that there are two heat pipes  33  and one fiber bundle  35 ; that the receiving space  313  further has a plurality of partitions  38  formed with a plurality of channels  39 ; that the partitions  38  are provided between and abut against the first plate  311  and the second plate  312  and separate the heated area H 3  from the cavities  331 ; that the partitions  38  do not abut against the heated area H 3 , the channels  39 , or the joints between the cavities  331  and the receiving space  313 ; that the heated area H 3  and the cavities  331  of the heat pipes  33  are in communication with each other only through the channels  39 ; that the fiber bundle  35  is partially in contact with the first capillary material  32  and partially extends into the heat pipes  33  through any two channels  39 ; and that the two ends of the fiber bundle  35  are in contact with the second capillary material  34 . The functions of the other components are the same as those in the first preferred embodiment and therefore will not be described repeatedly. 
     The heat dissipation device  30  disclosed in third preferred embodiment is so configured that the partitions  38  abutting against the first plate  311  and the second plate  312  provide the heat dissipation device  30  with additional structural support. Moreover, with the fiber bundle  35  extending through only some of the channels  39 , the working fluid is guided through the channels  39  where the fiber bundle  35  extends when in a liquid state, and flows through the channels  39  where the fiber bundle  35  is absent when in a gaseous state. Thus, the partitions  38  formed with the channels  39  not only reinforce the heat dissipation device  30  structurally, but also are effective in guiding the liquid-state portion and the gaseous portion of the working fluid through different channels  39 , preventing the high-speed gaseous portion from interfering with the reflow of the working fluid; consequently, high thermal conduction efficiency can be achieved.