Abstract:
A hot press mold for a MEA of fuel cell is provided. The hot press mold includes: a first mold including a first alignment part; a second mold including a second alignment part, being piled up a first electrode, a film, and a second electrode on it, whereby the first and second alignment parts join together to pile the first electrode, the film, and the second electrode between the first and second mold; and a lock loop secures the edge of the first and second mold to fix the first and second mold.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 097106732 filed in Taiwan, R.O.C. on Feb. 2, 2008, the entire contents of which are hereby incorporated by reference. 
       FIELD OF INVENTION 
       [0002]    This invention relates to a hot press mold, and more particularly to a hot press mold for the membrane electrode assembly (MEA), of a fuel cell. 
       BACKGROUND 
       [0003]    The natural resources of the earth diminish with the fast development of global industries, forcing the energy engineering industry to increase efforts to research an energy technology with the advantages of low-pollution, reusability and high conversion rate. Thus fuel cells, having a high energy conversion rate, become the focus of attention. Out of every kind of fuel cell, proton exchange membrane fuel cells (PEMFC) are the most popular, due to their fast activation, low activation temperature, higher power density and no electrolyte corrosion or leakage. 
         [0004]    The main structure of PEMFC is the MEA which consists of the membrane, the electrodes, and the gas diffusion layers. The first step of the hot press process is to place the anode (or cathode) on the heatsink. The second is to pile the proton exchangeable membrane, cathode (or anode) and the heatsink on the previous electrode in sequence. The last is to place another heatsink on the top side and put the whole assembly onto a machine which has been pre-heated to the setting temperature. The machine compresses and heats the whole assembly so that the electrodes and the proton exchangeable membrane will adhere to each other to form the MEA. After the compressing and heating process are completed, the machine starts to cool down. As the cooling process is completed, the MEA can be removed from the heatsink. 
         [0005]    However, this method of manufacturing MEA has the following problems. During the piling process, movement occurs between the electrodes and the membrane that results in a dimension deviation of the MEA. In addition, the hot press process could also cause such movement to occur during assembly. Furthermore, the MEA must be cooled down under a constant compressing pressure to prevent dimension distortions and undesirable adhering problems. Thus the conventional manufacturing method of MEA has a long cycle time and is inefficient. Furthermore, the repeated heating-cooling and continuous compressing process will increase process time and decrease the lifetime of the machine. 
         [0006]    Therefore, the primary issues to be solved are improving the structure of the hot press mold to make each component of the assembly align more easily, ensuring the MEA can be cooled outside the machine (reducing cooling time), and increasing the lifetime of the hot press machine by avoiding a repetitious heating-cooling process. 
       SUMMARY 
       [0007]    In view of these problems, this invention presents a hot press mold for the MEA of a fuel cell including: a first mold, a second mold, and a lock loop, wherein the first mold includes a first alignment part, and the second mold includes a second alignment part. A first electrode, a membrane and a second electrode are piled onto the second mold. The first alignment part connects with the second alignment part to combine the first mold with the second mold, which positions the first electrode, the membrane and the second electrode between the first mold and the second mold. The lock loop secures the edge of the first mold and the second mold and consequently fixes the first mold and the second mold. 
         [0008]    The second mold has an electrode alignment groove and a membrane alignment groove to accommodate the second electrode and the membrane individually, and the first electrode is placed on the membrane through an electrode alignment plate. So each component of the assembly is piled up more easily and more accurately, and the dimension of the assembly is not influenced by the movement occurring between the first mold and the second mold. 
         [0009]    Due to the fact that there are several first electrodes, membranes and second electrodes to be placed between the first mold and the second mold, several MEAs are manufactured at the same time and production efficiency is improved significantly. 
         [0010]    Furthermore, after heating the first mold and the second mold completely, the lock loop is rotated to shorten the distance between the first mold and the second mold, which can then be moved elsewhere to cool, thus reducing significantly the MEA production process time. Furthermore, a circulating fluid can be placed in the first mold or the second mold or both to improve cooling efficiency. 
         [0011]    The preferred embodiments and effects related to the present invention will be described in detail with the following figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The following detailed description of the embodiments of the present invention can be best understood when read in conjunction with the following drawings, in which device parts are identified with reference numerals and in which: 
           [0013]      FIG. 1A  is an outline diagram of the assembly of the first embodiment; 
           [0014]      FIG. 1B  is an exploded diagram of the first embodiment. 
           [0015]      FIG. 2A  is a structure diagram of the first mold of the first embodiment. 
           [0016]      FIG. 2B  is a structure diagram of the second mold of the first embodiment. 
           [0017]      FIG. 2C  is a structure diagram of the electrode alignment plate of the first embodiment. 
           [0018]      FIG. 2D  is a structure diagram of the lock loop of the first embodiment. 
           [0019]      FIG. 3A  is a cross-section diagram of the assembly of the second embodiment (1). 
           [0020]      FIG. 3B  is a cross-section diagram of the assembly of the second embodiment (2). 
           [0021]      FIG. 4A  is a structure diagram of the second mold of the third embodiment. 
           [0022]      FIG. 4B  is a structure diagram of the electrode alignment plate of the third embodiment. 
           [0023]      FIG. 5  is a structure diagram of the second mold of the fourth embodiment. 
           [0024]      FIG. 6  is a structure diagram of the second mold of the fifth embodiment. 
           [0025]      FIG. 7  is a structure diagram of the lock loop of the sixth embodiment. 
           [0026]      FIG. 8A  is a structure diagram of the first mold of the seventh embodiment. 
           [0027]      FIG. 8B  is a structure diagram of the second mold of the seventh embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    Please refer to  FIG. 1A ,  1 B,  2 A,  2 B,  2 C and  2 D, which is the first embodiment of the present invention, wherein  FIG. 1A  is a diagram of the assembly&#39;s outline,  FIG. 1B  is an exploded diagram;  FIG. 2A  is a structure diagram of the first mold,  FIG. 2B  is a structure diagram of the second mold;  FIG. 2C  is a structure diagram of the electrode alignment plate;  FIG. 2D  is a structure diagram of the lock loop. 
         [0029]    The hot press mold for MEA of fuel cell includes: the first mold  10 , the second mold  30  and the lock loop  40 . 
         [0030]    The first mold  10  has a body  11  which is substantially round, a plurality of first alignment parts  12  set on one surface of the body  11 , and a projection  14  set on the other surface of the body  14 . 
         [0031]    The second mold  30  has a body  31  which is substantially round, a plurality of second alignment parts  32  set on the body  31 , and a second external thread  33  is set at the outer surface of the body  31 . In addition, an electrode alignment plate  34  and a membrane alignment groove  35  are set on the body  31 , and a part of the area of the membrane alignment groove  35  overlaps the electrode alignment groove  34 . 
         [0032]    The above-mentioned first alignment part  12  can be a first alignment pin, and the second alignment part  32  can be a second alignment hole. When the first mold  10  is combined with the second mold  30 , the first alignment pin is inserted into the second alignment hole to position the first mold  10  on the second mold  30 . In addition, the first alignment part  12  can be a first alignment hole, and the second alignment part  32  can be a second alignment pin. When the first mold  10  is combined with the second mold  30 , the second alignment pin will be inserted into the first alignment hole to position the first mold  10  on the second mold  30 . The following description takes the first alignment part  12  as the first alignment hole, the second alignment part  32  as the second alignment pin. 
         [0033]    The lock loop  40  is substantially round, the central part is a through-hole  41 , and the inner surface of the lock loop  40  has an inner thread  42  which matches with the second outer thread  33 . The lock loop  40  secures the edge of the first mold  10  and the second mold  30  so that the first mold  10  and the second mold  30  can be fixed. 
         [0034]    An optional first outer thread (not shown) may be added to the outer surface of the body  11  of the above-mentioned first mold  10 , where the first outer thread matches with the inner thread  42 . The first outer thread is used to fix the first mold  10  and the lock loop  40 . 
         [0035]    The hot press mold of the fuel cell MEA further includes an electrode alignment plate  20  placed between the first mold  10  and the second mold  30 , which has an electrode guiding tunnel  21  and a plurality of through-holes  22 . The second alignment part  32  passes through the through-hole  22  and is inserted into the first alignment part  12 . 
         [0036]    The first step of manufacturing the MEA is to place the second electrode  50   b  into the electrode alignment groove  34  and to place the membrane  51  into the membrane alignment groove  35 . Next, the electrode plate  20  is piled on the second mold  30  and the first electrode  50   a  is piled on the membrane  51  through electrode guiding tunnel  21 . The first electrode  50   a , membrane  51  and the second electrode  50   b  pile on the second mold  30  in sequence, and the electrode alignment plate  20  can subsequently be removed. Then, the first mold  10  is stacked on the second mold  30 , while the second alignment part  32  passes through the through-hole  22  and is inserted into the first alignment part  12  to position first electrode  50   a , membrane  51  and the second electrode  50   b  between the first mold  10  and the second mold  30 . Next the lock loop  40  is hitched to the first mold  10  and the second mold  30  and the projection  14  of the first mold  10  lodges in the through-hole  41  of the lock loop  40 . Finally the lock loop  40  is rotated to tighten the first mold  10  and the second mold  30 . 
         [0037]    The top surface of the projection  14  is higher than the top surface of the body  11 , but it is not a restriction on the present invention. In addition, the above-mentioned membrane  51  is a proton exchangeable membrane, but it is not a restriction on the present invention. 
         [0038]    After completing the above-mentioned steps, the whole assembly is hot pressed in the hot press machine. If the top surface of the projection  14  is higher than the body  11 , then the hot press machine will press the MEA through the projection  14 . So the first electrode  50   a , the membrane  51  and the second electrode  50   b  adhere to each other to form the MEA. After completing the hot press process, lock loop  40  is rotated to tighten the first mold  10  and the second mold  30  and the whole assembly is removed from the hot press machine to cool. The cooling method for the hot-pressed assembly includes: water cooling, air cooling and contact cooling. After the assembly is cooled down, the lock loop  40  is loosened to separate the first mold  10  from the second mold  30 . The MEA is then removed from the first mold  10  and second mold  30 . Since the cooling process is not executed in the hot press machine, the present invention avoids the problem of overlong process time, and also increases the lifetime of the hot press machine. Furthermore, the present invention aligns first electrode  50   a , the membrane  51 , and the second electrode  50   b  more easily and accurately. 
         [0039]    Please refer to  FIG. 3A  and  FIG. 3B , which are the second embodiment of the present invention, where  FIG. 3A  is a cross-section diagram of the assembly ( 1 ) and  FIG. 3B  is a cross-section diagram of the assembly ( 2 ). 
         [0040]    In the present embodiment the projection  15  which is corresponds to the electrode guiding tunnel  21  is placed on one of the surface of the body  11  of the first mold  10 . The size of the projection  15  is matched with the electrode guiding tunnel  21  (as shown in  FIG. 3A ). First, the electrode alignment plate  20 , the first electrode  50   a , the membrane  51  and the second electrode  50   b  are piled on the second mold  30  in sequence. Secondly, the first mold  10  is stacked on the second mold  30  and the second alignment part  32  passes through the through-hole  22  and is inserted into the first alignment part  12  to position the first electrode  50   a , the membrane  51  and the second electrode  50   b  between the first mold  10  and the second mold  30 , while the projection  15  is plugged into the electrode guiding tunnel  21  and presses the first electrode  50   a.    
         [0041]    Furthermore, the cross-section area of the projection  15  is between that of the electrode alignment groove  34  and the membrane alignment groove  35  (as shown in  FIG. 3B ). The height of the projection  15  is longer than the sum of the depth of the electrode alignment groove  34  and the membrane alignment groove  35 . First, the electrode alignment plate  20  is stacked on the second mold  30 . Second, the first electrode  50   a , the membrane  51  and the second electrode  50   b  are piled in sequence, and the electrode alignment plate  20  is subsequently removed. Third, the first mold  10  is stacked on the second mold  30 . Finally, the second alignment part  32  is passed through the through-hole  22  and inserted into the first alignment part  12  to position the first electrode  50   a , the membrane  51  and the second electrode  50   b  between the first mold  10  and the second mold  30 . 
         [0042]    Please refer to  FIG. 4A  and  FIG. 4B , which constitute the third embodiment of the present invention.  FIG. 4A  is a structure diagram of the second mold and  FIG. 4B  is a structure diagram of the electrode alignment plate. 
         [0043]    In the present embodiment the top of the body  31  of the second mold  30  has a plurality of the electrode alignment grooves  34  and the membrane alignment grooves  35 . The electrode alignment plate  20  has a plurality of the electrode guiding tunnels  21  corresponding to the electrode alignment grooves  34 , wherein the number of the electrode alignment groove  34 , the membrane alignment grooves  35  and the electrode guiding tunnels  21  depends on the requirement. The purpose of the present embodiment is to manufacture several MEAs at the same time and improve the production efficiency significantly. 
         [0044]    The first mold  10  has a plurality of projections  15 , corresponding to the electrode guiding tunnels  21 , for pressing the first electrode  50   a  in each of the electrode guiding tunnel  21 . 
         [0045]    Please refer to  FIG. 5 , which is a structure diagram of the second mold of the fourth embodiment, wherein the body  31  of the second mold  30  has a plurality of trenches  36 , connecting the electrode alignment groove  34  and the membrane alignment groove  35  to the outer space, to release the gas generated during the hot press process. If the second mold  30  only has the electrode alignment groove  34 , the trench  36  only connects the electrode alignment groove  34  to the external space to release the gas generated during hot press process. 
         [0046]    Please refer to  FIG. 6 , which is a structure diagram of the second mold of the fifth embodiment of the present invention. The external surface of the body  31  of the second mold  30  has a plurality of inserting-holes. By inserting a specific tool into the inserting-holes, the assembly may be moved easily and safely. 
         [0047]    Please refer to  FIG. 7 , which is a structure diagram of the lock loop of the sixth embodiment. The outside surface of the lock loop  40  has a plurality of plugging-holes  44 . By inserting a specific tool into the plugging-holes  44 , the lock loop  40  may be rotated easily to tighten the first mold  10  and second mold  30 , while tightening the first electrode  50   a , the membrane  51 , and the second electrode  50   b.    
         [0048]    Please refer to  FIG. 8A  and  FIG. 8B , which is the seventh embodiment of the present invention, wherein,  FIG. 8A  is a structure diagram of the first mold and  FIG. 8B  is a structure diagram of the second mold. 
         [0049]    In order to improve the cooling effect, a first channel  18  is cut zigzag in the body  11  of the first mold  10 . Both ends of the first channel  18  have a first connector  181  for connecting a pipe which allows cooling liquid to flow in and transfer the heat. A second channel  38  is cut zigzag in the body  31  of the second mold  30 . Both ends of the second channel  38  have a second connector  381  for connecting a pipe which allows cooling liquid to flow in and transfer the heat. The present embodiment improves the cooling effect and shortens the time required for cooling. 
         [0050]    The above-mentioned description is not used to limit the present invention. Though the embodiment of setting both of the first channel  18  and the second channel  38  is described above, the first channel  18  may alternatively be set in the first mold  10  and in the second mold  30 . The second channel  38  is optional. 
         [0051]    The technical contents of the present invention have been disclosed with preferred embodiments as above. However, the disclosed embodiments are not used to limit the present invention. Those proficient in the relevant fields could make slight changes and modification without departing from the spirit of the present invention, and the changes and modification made thereto are all covered by the scope of the present invention. The protection scope for the present invention should be defined with the attached claims.