Abstract:
The present invention relates to a method for sealing a heat transfer unit, which includes the steps of providing a heat transfer unit having at least one opening, welding the opening to form a welding section and close the opening, and pinching off the welding section and cutting part of the welding section to form a cutting end and complete sealing the opening of the heat transfer unit. By means of the method of the present invention, an extremely short dead zone can be obtained and high heat conduction efficiency is enhanced, further having the effects of reducing the arrangement space and shrinking steps of the heat pipe.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a method for sealing a heat transfer unit and in particular to a method for sealing a heat transfer unit, which significantly reduces the length of the dead zone and improves heat conduction efficiency. 
         [0003]    2. Description of Prior Art 
         [0004]    With the rapid development of electronic information industry, the processing capability of the electronic device such as a CPU increasingly grows with the increasing generated heat. The heat-dissipation module combining a heat-dissipation fin and a fan has not been able to meet the requirement of heat dissipation, especially for a notebook computer. The heat pipe is a currently and commonly used device for heat transfer. The heat pipe can be considered a passive heat transfer device with high heat conductivity. Using the mechanism of two-phase heat transfer, the heat transfer capability of the heat pipe is hundreds times as large as copper having the same size. The heat pipe used as a medium of heat transfer has the advantages of fast response and small heat resistance. Therefore, the highly efficient heat-dissipation module developed from the heat pipe or its derived product is suitable to solve the heat-dissipation problems caused by high performance electronic products. 
         [0005]    As for the traditional method for sealing a heat pipe, the heat pipe is firstly vacuumed through a pipe opening and a working liquid is filled in the heat pipe. Then, the pipe opening is stretched and shrinks to form a necking end. Next, welding (e.g., argon welding) is performed at the necking end. In this way, the necking end is sealed. However, the necking section of the traditional heat pipe cannot conduct heat, which results in a dead zone of heat transfer. The dead zone will lower heat conduction efficiency of the heat pipe (that is, poor heat conduction of the heat pipe). Also, the necking section of the heat pipe is longer, which shortens the effective heat transfer length of the heat pipe such that when the heat pipe is installed in a smart mobile device such as a smart watch, a smart phone, or a wearable device, the occupied space of the heat pipe will make the assembly of the smart mobile device difficult, which is unfavorable to the shrinking of the smart mobile device. 
         [0006]    Therefore, how to overcome the above problems and disadvantages is the focus which the inventor and the related manufacturers in this industry have been devoting themselves to. 
       SUMMARY OF THE INVENTION 
       [0007]    Thus, to effectively overcome the above problems, the primary objective of the present invention is to provide a method for sealing a heat transfer unit, which can effectively reduce the length of the dead zone and improves heat conduction efficiency 
         [0008]    Another objective of the present invention is to provide a method for sealing a heat transfer unit, which can effectively reduce the arrangement space when the sealed heat pipe is used. 
         [0009]    Yet another objective of the present invention is to provide a method for sealing a heat transfer unit, which can reduce the shrinking steps of the heat pipe. 
         [0010]    To achieve the above objectives, the present invention provides a method for sealing a heat transfer unit, which includes the steps of (a) to (c). Step (a) provides a heat transfer unit having a chamber and forming at least one opening, wherein an inner wall of the chamber forms at least one wick structure, wherein a working fluid is filled in the chamber; Step (b) welds the opening to form a welding section and close the opening; and Step (c) pinches off the welding section and cuts part of the welding section to form a cutting end and complete sealing the opening of the heat transfer unit. By means of the method of the present invention, an extremely short dead zone can be obtained and high heat conduction efficiency is enhanced, further having the effects of reducing the arrangement space and shrinking steps of the heat pipe. 
     
    
     
       BRIEF DESCRIPTION OF DRAWING 
         [0011]      FIG. 1  is a flow chart of the method for sealing a heat transfer unit according to the first embodiment of the present invention; 
           [0012]      FIG. 2A  is a schematic view of a method for sealing a heat transfer unit according to the first preferred embodiment of the present invention in the first state; 
           [0013]      FIG. 2B  is a schematic view of a method for sealing a heat transfer unit according to the first preferred embodiment of the present invention in the second state; 
           [0014]      FIG. 2C  is a schematic view of a method for sealing a heat transfer unit according to the first preferred embodiment of the present invention in the third state; 
           [0015]      FIG. 2D  is a schematic view of a method for sealing a heat transfer unit according to the first preferred embodiment of the present invention in the fourth state; 
           [0016]      FIG. 3  is a view of the finished product made by the method for sealing a heat transfer unit according to the first preferred embodiment of the present invention; 
           [0017]      FIG. 4A  is a schematic view of a method for sealing a heat transfer unit according to the second preferred embodiment of the present invention in the first state; 
           [0018]      FIG. 4B  is a schematic view of a method for sealing a heat transfer unit according to the second preferred embodiment of the present invention in the second state; 
           [0019]      FIG. 4C  is a schematic view of a method for sealing a heat transfer unit according to the second preferred embodiment of the present invention in the third state; 
           [0020]      FIG. 4D  is a schematic view of a method for sealing a heat transfer unit according to the second preferred embodiment of the present invention in the fourth state; 
           [0021]      FIG. 5  is a view of the finished product made by the method for sealing a heat transfer unit according to the second preferred embodiment of the present invention; 
           [0022]      FIG. 6A  is a schematic view of a method for sealing a heat transfer unit according to the third preferred embodiment of the present invention in the first state; 
           [0023]      FIG. 6B  is a schematic view of a method for sealing a heat transfer unit according to the third preferred embodiment of the present invention in the second state; 
           [0024]      FIG. 6C  is a schematic view of a method for sealing a heat transfer unit according to the third preferred embodiment of the present invention in the third state; 
           [0025]      FIG. 6D  is a schematic view of a method for sealing a heat transfer unit according to the third preferred embodiment of the present invention in the fourth state; and 
           [0026]      FIG. 7  is a view of the finished product made by the method for sealing a heat transfer unit according to the third preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    The present invention is to provides a method of removing the dead zone of a flat heat pipe. 
         [0028]    Please refer to  FIG. 1 , which is a flow chart of the method for sealing a heat transfer unit according to the first embodiment of the present invention. Please also refer to  FIGS. 2A, 2B, 2C, 2D, and 3 . In the current embodiment, a cylindrical heat pipe is used as an example of the heat transfer unit  1  for explanation. The method for sealing a heat transfer unit includes the following steps. 
         [0029]    Step ( 100 ): providing a heat transfer unit having a chamber and forming at least one opening, wherein an inner wall of the chamber forms at least one wick structure, wherein a working fluid is filled in the chamber. 
         [0030]    The heat transfer unit  1  which is a cylindrical heat pipe is provided. The heat transfer unit  1  has a chamber  11  therein; each of two ends of the heat transfer unit  1  has an opening  12  communicating with the chamber  11 . An inner wall of the chamber  11  forms at least one wick structure  13 . In the current embodiment, sintered powder is used as an example of the wick structure  13  for explanation, but not limited to this. In practice, the wick structure  13  may be grooves, a metal net, or a fiber net. A working fluid  14  (e.g., pure water, inorganic compound, alcohols, ketones, liquid metal, coolant, or organic compound) is filled in the chamber  11 . Two dead zones  15  are individually defined between the wick structure  13  and each of the two opposite openings  12  at two ends of the heat transfer unit  1 . The wick structure  13  is not formed in the dead zones  15 , which helps the working fluid  14  be filled into the chamber  11 . Therefore, the dead zones  15  of the heat transfer unit  1  cannot be used for heat transfer. 
         [0031]    Step ( 101 ): welding the opening to form a welding section and close the opening. 
         [0032]    Two openings  12  at two ends of the heat transfer unit  1  have the dead zones  15 . In the current embodiment, the dead zones  15  are the portions which cannot carry out heat transfer on the heat transfer unit  1  and in which the wick structure  13  is not formed. Ultrasonic welding is performed on the dead zones  15  via ultrasonic welding equipment  5 . The inner wall in the portion of welding is welded and closed. Also, a certain range of the inner wall is required to be closed during the ultrasonic welding. Thus, after the ultrasonic welding is performed on two openings  12  of the heat transfer unit  1 , two welding sections  2  will be produced individually to close the individual openings  12 . Besides, the chamber  11  is vacuumed during the closing process to become a vacuumed chamber  11 . 
         [0033]    Step ( 102 ): pinching off the welding section and cutting off part of the welding section to form a cutting end and complete sealing the opening of the heat transfer unit. 
         [0034]    After the ultrasonic welding is performed, two ends of the heat transfer unit  1  individually form the welding section  2 . Besides, a certain range of the welding section  2  is required to be closed during the welding. Therefore, the pinch-off equipment  6  is used to pinch off the welding section  2  and cut off part of the welding section  2 . At the pinch-off location of the welding section  2 , the pinch-off equipment  6  closes the welding section  2  again to form a cutting end  3  such that the welding section  2  and the cutting end  3  can be closed effectively and thus the heat transfer unit  1  is sealed. 
         [0035]    Therefore, the design of the present invention can be directly applied in a common finished heat transfer unit  1 , such as the above-mentioned cylindrical heat pipe, the flat heat pipe, the heat conducting plate or vapor chamber formed by an upper plate and an lower plate stacked to each other, to reduce the length of the dead zone  15  and minimize the area disposed by the dead zone  15 . As a result, the heat conduction efficiency of the heat transfer unit  1  can be relatively improved. (That is, the heat transfer unit  1  is almost the effective area.). In addition, after the dead zone  15  is effectively reduced by means of the design of the present invention, the whole length of the heat transfer unit  1  can be effectively reduced, resulting in a heat transfer unit  1  with a short and small size. In this way, when the heat transfer unit  1  of the present invention is applied in a smart mobile device such as a smart watch, smart phone, or wearable device, it occupies little space and has a space saving effect, facilitating size reduction of smart mobile devices. 
         [0036]    Please also refer to  FIGS. 1, 4A, 4B, 4C, 4D, and 5 , which are flow charts of a method for sealing a heat transfer unit according to the second preferred embodiment of the present invention. The current embodiment uses a flat heat pipe for explanation, instead of a cylindrical heat pipe as the heat transfer unit  1  of the first embodiment. In the current embodiment, the method for sealing a heat transfer unit mainly includes the following steps. First, a heat transfer unit  1  is provided, which is a finished product of the flat-pressed heat pipe. The heat transfer unit  1  has a chamber  11  therein; each of two ends of the heat transfer unit  1  has an opening  12 . The inner wall of the chamber  11  forms the wick structure  13 ; the working fluid  14  is filled in the chamber  11 . Two dead zones  15  are individually defined between the wick structure  13  of an inner wall of the heat transfer unit  1  and each of the two opposite openings  12  at two ends of the heat transfer unit  1 . Then, the two ends of the heat transfer unit  1  form the welding sections  2  after the ultrasonic welding is performed. Next, the welding sections  2  are pinched off using the pinch-off equipment  6  and part of the welding sections  2  are cut off. At the pinch-off location of the welding section  2 , the pinch-off equipment  6  closes the welding section  2  again to form a cutting end  3  such that the welding section  2  and the cutting end  3  can be closed effectively and thus the heat transfer unit  1  is sealed. In the way, after the dead zone  15  is effectively reduced by means of the design of the present invention, the whole length of the heat transfer unit  1  can be effectively reduced, resulting in a heat transfer unit  1  with a short and small size. Therefore, when the heat transfer unit  1  of the present invention is applied in a smart mobile device such as a smart watch, smart phone, or wearable device, it occupies little space and has a space saving effect, facilitating size reduction of smart mobile devices. 
         [0037]    Please refer to  FIGS. 1, 6A, 6B, 6C, 6D, and 7 , which are flow charts of a method for sealing a heat transfer unit according to the third preferred embodiment of the present invention. The current embodiment uses a flat vapor chamber formed by an upper plate and a lower plate stacked to each other as an example of the heat transfer unit  1  for explanation, instead of the heat transfer unit  1  of the first embodiment. In the current embodiment, the method for sealing a heat transfer unit mainly includes the following steps. First, a heat transfer unit  1  is provided, which is a flat vapor chamber. The heat transfer unit  1  has a chamber  11  therein and a filling section  4  at one end thereof. An opening  12  is formed in the filling section  4 . The inner wall of the chamber  11  is provided with the wick structure  13 ; the working fluid  14  is filled in the chamber  11 . The wick structure  13  is not disposed in the filling section  4  and thus the filling section  4  is a dead zone  15  in the current embodiment. Next, the filling section  4  of the heat transfer unit  1  is welded by the ultrasonic welding to form a welding section  2 . The welding sections  2  are pinched off using the pinch-off equipment  6  and part of the welding sections  2  are cut off. At the pinch-off location of the welding section  2 , the pinch-off equipment  6  closes the welding section  2  again to form a cutting end  3  such that the welding section  2  and the cutting end  3  can be closed effectively and thus the heat transfer unit  1  is sealed. In the way, after the dead zone  15  is effectively reduced by means of the design of the present invention, the whole length of the heat transfer unit  1  can be effectively reduced, resulting in a heat transfer unit  1  with a short and small size. Thus, when the heat transfer unit  1  of the present invention is applied in a smart mobile device such as a smart watch, smart phone, wearable device, or tablet computer, it occupies little space and has a space saving effect, facilitating size reduction of smart mobile devices. 
         [0038]    In summary, compared with the traditional method, the present invention has the following advantages. 
         [0039]    1. The length of the dead zone can be reduced. 
         [0040]    2. The heat conduction efficiency of the heat transfer unit can be improved. 
         [0041]    3. The space is saved. 
         [0042]    The above-mentioned embodiments are only the preferred ones of the present invention. All variations regarding the above method, shape, structure, and device according to the claimed scope of the present invention should be embraced by the scope of the appended claims of the present invention