Patent Publication Number: US-2012031587-A1

Title: Capillary structure of heat plate

Description:
FIELD OF THE INVENTION 
     The present invention relates to a structure of heat plate, and in particular to a capillary structure of a heat plate applicable to an electronic device. 
     BACKGROUND OF THE INVENTION 
     An electronic device often generates a great amount of heat during a long term operation. A common solution for handling such a great amount of heat is installation of a heat plate that dissipates the heat. A heat plate is advantageous in respect of high heat conductivity, light weight, and simple construction and can carry out transfer of a large amount of heat without consuming electrical power. 
     A conventional heat plate structurally comprises a board, which has a hollow interior forming a chamber that receives and retains therein a capillary tissue and is filled with a working fluid. Connected to one side of the board is a sealing tube (or referred to an opening sealing tube, a degassing tube, or a filling and degassing tube), which has an end mounted to the board and communicating the hollow interior chamber, so that the working fluid can be filled from the outside into the interior (namely the chamber) of the board through the sealing tube and degassing and air evacuation operations can also be performed through the sealing tube in order to realize the destination function of removal of heat from an electronic device. 
     Thus, the present invention aims to provide a capillary structure of a heat plate that helps increasing the efficiency of reduction of temperature in order to extend the lifespan of an electronic device. 
     SUMMARY OF THE INVENTION 
     A primary objective of the present invention is to provide a capillary structure of a heat plate that improves temperature reduction efficiency of the heat plate. 
     To realize the above objectives, the present invention provides a heat plate comprising two boards, which mate and are coupled to each other to define therebetween an accommodation chamber, at least one first capillary layer received in the accommodation chamber, and at least one second capillary layer received in the accommodation chamber in such a way that the first and second capillary layers are stacked over each other. With the arrangement of the first and second capillary layers, the efficiency of diffusion of vapor of a working fluid is increased and the uniformity of distribution of the working fluid is enhanced, so that the efficiency of temperature reduction is improved to thereby offer practicability, novelty, improvement, and convenience. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be apparent to those skilled in the art by reading the following description of preferred embodiments thereof with reference to the drawings, in which: 
         FIG. 1A  is an exploded view of a heat plate according to a first embodiment of the present invention; 
         FIG. 1B  is a perspective view illustrating two boards of the heat plate of the first embodiment coupled together according to the present invention; 
         FIG. 1C  a perspective view of the heat plate according to the first embodiment of the present invention in an assembled form; 
         FIG. 1D  is a cross-sectional view taken along line A-A′ of  FIG. 1C ; 
         FIG. 2A  is an exploded view of a heat plate according to a second embodiment of the present invention; 
         FIG. 2B  is a perspective view of a capillary structure comprising first and second capillary layers stacked over each other contained in the heat plate of the second embodiment of the present invention; 
         FIG. 2C  is a perspective view of the heat plate of the second embodiment in an assembled form; 
         FIG. 2D  is a cross-sectional view taken along line B-B′ of  FIG. 2C ; 
         FIG. 3  is an exploded view of a heat plate according to a third embodiment of the present invention; and 
         FIG. 4  is an exploded view of a heat plate according to a fourth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the drawings and in particular to  FIGS. 1A-1D , which respectively show an exploded view of a heat plate according to a first embodiment of the present invention, a perspective view illustrating two boards of the heat plate coupled together, a perspective of the heat plate, and a cross-sectional view of the heat plate, the heat plate constructed in accordance with the present invention comprises two boards  100 , a sealing tube  110 , at least one first capillary layer  210 , and at least one second capillary layer  220  and realizes functions of lowering temperature of a heat source, performing effective transfer of heat, and improving temperature reduction efficiency. 
     The two boards  100  are mated and coupled to each other so that the two boards  100  defined an accommodation chamber  101  therebetween. In a practical arrangement, one of the two boards  100  is structured to form a recess  102 , or alternatively, both boards  100  are structured to form corresponding recesses  102 , so that when the two boards  100  are coupled to each other, an accommodation chamber  101  that is in a vacuum condition and receives a working fluid therein is formed. The two boards  100  can be coupled in various ways, such as being jointed with copper paste or silver paste through blazing, diffusion bounding, or welding. 
     The sealing tube  110 , which is a hollow tubular body, is mounted to any side or any corner of the two coupled boards  100 . The sealing tube  110  has an end communicating the accommodation chamber  101  to allow the working fluid to be filled from the outside through the sealing tube  110  into the accommodation chamber  101 , whereby through changes between two phases, the working fluid is circulated through the first capillary layer  210  and the second capillary layer  220 , which collectively form a capillary structure, arranged between the two boards  100 , and consequently, the functions of lowering temperature of heat source and performing effective transfer and dissipation of heat can be realized. 
     The first and second capillary layers  210 ,  220  are arranged in the accommodation chamber  101  in such a way that the first and second capillary layers  210 ,  220  are stacked over each other. The stacked first and second capillary layers  210 ,  220  have an overall thickness that is substantially identical to a depth of the accommodation chamber  101 . The first and second capillary layers  210 ,  220  can be metal nets (or alternatively, the second capillary layer  220  is formed of sintered powders (such as metal powders)). The first capillary layer  210  has a thickness that is greater than a thickness of the second capillary layer  220  and the first capillary layer  210  has a mesh that is smaller than a mesh of the second capillary layers  220 . (Namely, the first capillary layer  210  is a “coarse metal net”, while the second capillary layer  220  is a “fine metal net”.) 
     In the instant embodiment, two boards  100 , a first capillary layer  210 , and a second capillary layer  220  are included, wherein one of the two boards  100  forms a recess  102  so that the two boards  100 , when mating and coupled to each other, form an accommodation chamber  101  therebetween, and a sealing tube  110  is mounted to a corner of the two coupled boards  100  and has an end communicating the accommodation chamber  101 . The first and second capillary layers  210 ,  220  are received in the accommodation chamber  101  and the second capillary layer  220  is stacked under the first capillary layer  210 . The shape of the first and second capillary layers  210 ,  220  is complementary to a shape of the recess  102  of the board(s)  100 . The overall thickness of the stacked first and second capillary layers  210 ,  220  is substantially identical to a depth of the accommodation chamber  101  so that the capillary layers can be snugly, or even tightly, received in the accommodation chamber  101  to improve structural stability for positioning and supporting the capillary layers. Through the sealing tube  110 , a working fluid (such as water) is filled into the chamber between the two boards  100 , whereby through changes between two phases of the working fluid and circulation of the working fluid conducted by the capillary structure arranged between the two boards  100 , the functions of lowering temperature of heat source and performing effective transfer of heat can be realized. Meanwhile, when the working fluid undergoes changes between two phases (such as liquid water and water vapor), the vapor phase of the working fluid (such as water vapor) is allowed to uniformly diffuse to the upper board  100  through the first capillary layer  210 , thereby improving vapor diffusion efficiency, and, on the other hand, the liquid phase of the working fluid (such as water) is caused by the second capillary layer  220  to uniformly distribute over the lower board  100  to improve uniformity of distribution of the working fluid, thereby improving temperature reduction efficiency. 
     Referring to  FIGS. 2A-2D , which respectively show an exploded view of a heat plate according to a second embodiment of the present invention, a perspective view of a capillary structure adopted in the heat plate of the second embodiment, a perspective view of the heat plate of the second embodiment in an assembled form, and a cross-sectional view of the heat plate of the second embodiment, the second embodiment is substantially similar to the first embodiment with a major difference residing in that the second capillary layer  220  has a shape corresponding to the recesses  102  of the board  100 , but the first capillary layer  210  has a shape that is arbitrary (such as a T-shape) and an overall thickness of the first and second capillary layers  210 ,  220  stacked together is substantially identical to a depth of the accommodation chamber  101 . The first capillary layer  210  has a periphery that forms one or more cutoffs  211 , whereby when the second capillary layer  220  is stacked under the first capillary layer  210 , the cutoff  210  allows the vapor phase of the working fluid (such as water vapor) to quickly pass therethrough to thereby enhance the efficiency of temperature reduction. 
     Referring to  FIG. 3 , which shows an exploded view of a heat plate according to a third embodiment of the present invention, the third embodiment is substantially similar to the first embodiment with a major difference residing in that two second capillary layers  220  are respectively stacked on and under top and bottom surfaces of the first capillary layer  210  and the second capillary layers  220  are shaped to correspond to the recess  102  of the board(s)  100 , but the first capillary layer  210  has a shape that is arbitrary (such as a T-shape). The first capillary layer  210  has a periphery that forms one or more cutoffs  211 . 
     Referring to  FIG. 4 , which shows an exploded view of a heat plate according to a fourth embodiment of the present invention, the fourth embodiment is substantially similar to the first embodiment with a major difference residing in that the first capillary layer  210  corresponds in shape to the second capillary layer  220  and both the first and second capillary layers  210 ,  200  are of an arbitrary but identical shape (such as a T-shape). The first capillary layer  210  has a periphery that forms one or more cutoffs  211  and the second capillary layer  220  also has a periphery that forms one or more cutoffs  221 . 
     The present invention provides a heat plate of which the features are that two boards  100  mate and are coupled to each other to form an internal accommodation chamber  101  and a capillary structure of at least one first capillary layer  210  and at least one second capillary layer  220  is received in the accommodation chamber  101  in such a way that the first and second capillary layers  210 ,  220  are stacked over each other, whereby when a working fluid contained in the accommodation chamber  101  undergoes phase change, vapor or gaseous phase of the working fluid is allowed to quickly pass through the first capillary layer  210  to improve vapor diffusion efficiency, and, on the other hand, the liquid phase of the working fluid is allowed to uniformly diffuse and flow through the second capillary layer  220  to enhance uniformity of distribution of the working fluid, thereby improving temperature reduction efficiency. 
     Although the present invention has been described with reference to the preferred embodiments thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims.