Patent Publication Number: US-2011065023-A1

Title: Sealing structure and electricity supply device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 098131133 filed in Taiwan, Republic of China on Sep. 15, 2009, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The invention relates to an electricity supply device and a sealing structure thereof, and in particular, to an electricity supply device and a sealing structure thereof that can enhance the sealing effect and reduce the manufacturing cost. 
     2. Related Art 
     For the sake of our environment and planet, it is desired to develop green energy technologies such as the fuel cell technology. The fuel cell can convert the chemical energy of the fuel by the electrochemical reaction to generate electricity. 
       FIG. 1  is an exploded diagram showing a conventional fuel cell device  1 . As shown in  FIG. 1 , the conventional fuel cell device  1  includes a conductive substrate  12   a,  a diffusion layer  14   a,  a membrane electrode  16 , a diffusion layer  14   b , and a conductive substrate  12   b.    
     The conductive substrates  12   a  and  12   b  include reaction areas Ra and Rb and transmission areas Ta and Tb, respectively. When the conductive substrate  12   a  is a cathode, the conductive substrate  12   b  is an anode. The transmission areas Ta and Tb allow the fluids to flow around the conductive substrates  12   a  and  12   b , respectively. In this case, the fluid flows around the conductive substrate  12   a  is a cathode fluid (not shown), and the fluid flows around the conductive substrate  12   b  is an anode fluid (not shown). In order to form the circuit loop, the diffusion layer  14   a  disposed adjacent to the conductive substrate  12   a  and the diffusion layer  14   b  disposed adjacent to the conductive substrate  12   b  both have electronic conductivity. The membrane electrode  16  disposed between the diffusion layers  14   a  and  14   b  is disposed corresponding to the reaction areas Ra and Rb. In addition, the membrane electrode  16  includes a catalyze layer  161 , a catalyze layer  162 , and a proton exchange layer  163  disposed between the catalyze layers  161  and  162 . The proton exchange layer  163  is solid electrolyte, so that it can separate the catalyze layers  161  and  162 , and prevent the fluids flowing around the conductive substrates  12   a  and  12   b  from contacting with each other. 
     In addition, the membrane electrode  16  can separate the cathode and the anode, and the fluids flowing around the cathode and the anode are separated as well. In order to prevent the leakage or mixing of the fluids flowing around the cathode and the anode, it is necessary to configure a sealing body  18   a  between the membrane electrode  16  and the conductive substrate  12   a  and a sealing body  18   b  between the membrane electrode  16  and the conductive substrate  12   b.  Because the fluid is usually gas, the sealing bodies  18   a  and  18   b  are also called a gasket. 
     As mentioned above, the sealing bodies  18   a  and  18   b  are disposed at two opposite sides of the membrane electrode  16 . Thus, when assembling the fuel cell device  1 , the sealing bodies  18   a  and  18   b  must be disposed on the conductive substrate  12   a  or  12   b.  For example, if the sealing body  18   b  is disposed on the conductive substrate  12   b  in advance, the sealing body  18   b  can be used as a position reference for disposing the diffusion layer  14   b,  the membrane electrode  16 , the diffusion layer  14   a , the sealing body  18   a  and the conductive substrate  12   a  in sequence. However, since the sealing body  18   a  or  18   b  is not firmly fixed on the conductive substrate  12   a  or  12   b , it may slide that will cause the problems of the positioning of the later components. Moreover, the sealing effect may be very bad. In addition, if the relative positions between the membrane electrode  16  and the sealing bodies  18   a  and  18   b  are not accurate, they may have relatively shifting due to the vibration or thermal expansion contraction later. This will affect the usable lifetime of the fuel cell device  1 . Besides, two sealing bodies  18   a  and  18   b  are needed in the fuel cell device  1 , so that the manufacturing cost of the fuel cell device  1  can not be sufficiently reduced. Furthermore, there are too many factors influencing the assembling of the fuel cell device  1 , so that the manufacturing yield thereof can be efficiently increased. 
     In order to solve the above-mentioned bottlenecks of the prior art, the invention is to provide an electricity supply device and a sealing structure thereof that utilize a novel sealing structure design, which can keep the sealing effect and can simplify the assembling of the fuel cell device to reduce the manufacturing cost. 
     SUMMARY OF THE INVENTION 
     An objective of the invention is to provide an electricity supply device and a sealing structure thereof that can use the sealing structure to achieve the purposes of positioning and sealing, thereby simplifying the assembling procedure, increasing the manufacturing yield, and decreasing the manufacturing cost. 
     Another objective of the invention is to provide an electricity supply device and a sealing structure thereof that can use a single structure to separate the cathode fluid and the anode fluid. 
     To achieve the above-mentioned objectives, the invention discloses a sealing structure applied in an electricity supply device, which further includes two conductive substrates and a chemical-electrical conversion module disposed between the conductive substrates. The chemical-electrical conversion module includes two diffusion units and a membrane electrode unit disposed between the diffusion units. The sealing structure includes a first protruding structure and a second protruding structure. The first protruding structure is against to two conductive substrates. At least one end of one diffusion unit and at least one end of the membrane electrode unit are against to the inner side of one end of the first protruding structure. The second protruding structure is disposed adjacent to the first protruding structure and is disposed against the other conductive substrate and the membrane electrode unit. At least one end of the other diffusion unit is disposed against the inner side of at least one end of the second protruding structure. 
     In the invention, the first protruding structure and the second protruding structure are separated components; otherwise, the first protruding structure and the second protruding structure are integrally formed as one piece. At lest one of the first and second protruding structures is flexible. At least one of the first and second protruding structures is made of silica gel, polyvinyl chloride (PVC), Polyethylene (PE), Polypropylene (PP), Polystyrene (PS), or their combinations. The first protruding structure and the second protruding structure may have the same dimension or different dimensions. At least one of the first and second protruding structures is continuously or discontinuously disposed around the edge of the conductive substrate. Each of the conductive substrates has at least one reaction area and at least two fluid transmission areas. Herein, the sealing structure may be continuously or discontinuously disposed around the edge of the reaction area, and/or the sealing structure may be continuously or discontinuously disposed around the edges of fluid transmission areas. 
     In addition, the invention also discloses an electricity supply device including two conductive substrates, a chemical-electrical conversion module, and a sealing structure. The chemical-electrical conversion module is disposed between the conductive substrates, and includes two diffusion units and a membrane electrode unit, which is disposed between the diffusion units. One of the diffusion units is disposed adjacent to one of the conductive substrates, and the other one of the diffusion units is disposed adjacent to the other one of the conductive substrates. The sealing structure includes a first protruding structure and a second protruding structure. The first protruding structure is disposed against the conductive substrates, and at least one end of one of the diffusion units and at least one end of the membrane electrode unit are disposed against the inner side of at least one end of the first protruding structure. The second protruding structure is disposed adjacent to the first protruding structure, and at least one end of the second protruding structure is disposed against at least one end of the membrane electrode unit and at least one end of the other one of the conductive units. 
     In the invention, each of the conductive substrates has at least one reaction area and at least two fluid transmission areas, and the reaction area is disposed corresponding to the chemical-electrical conversion module. The reaction area includes at least one fluid channel. The sealing structure is continuously or discontinuously disposed around the edge of the reaction area; otherwise, the sealing structure is continuously or discontinuously disposed around the edges of fluid transmission areas. At least one of the conductive substrates has a surface configured with at least one positioning structure, and the positioning structure is disposed corresponding to the sealing structure. Otherwise, at least one of the conductive substrates has a surface configured with at least one fixing structure for fixing the sealing structure. The membrane electrode unit includes two catalyze units and a proton exchanging unit. One of the catalyze units is disposed between one of the conductive substrates and one of the diffusion units, and the other one of the catalyze units is disposed between the other one of the conductive substrates and the other one of the diffusion units. The proton exchanging unit is disposed between the catalyze units. The first protruding structure and the second protruding structure are separated components or integrally formed as one piece. At lest one of the first and second protruding structures is flexible. At least one of the first and second protruding structures is made of silica gel, polyvinyl chloride (PVC), Polyethylene (PE), Polypropylene (PP), Polystyrene (PS), or their combinations. The first protruding structure and the second protruding structure have the same dimension or different dimensions. The electricity supply device is a fuel cell device. 
     As mentioned above, the electricity supply device of the invention has a sealing structure configured between two conductive substrates directly. This configuration can simplify the assembling procedure of the electricity supply device, and thus make the positioning of the membrane electrode module more accurate and easier. Moreover, it is cheaper to use only one sealing structure, which can still achieve good seaming effect for preventing the mixing and leakage of the cathode and anode fluids. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will become more fully understood from the detailed description and accompanying drawings, which are given for illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is an exploded diagram showing the conventional fuel cell device; 
         FIG. 2  is a schematic diagram of an electricity supply device according to an embodiment of the invention; 
         FIG. 3  is a schematic diagram showing the structure of the conductive substrate; and 
         FIG. 4  is a cross-sectional diagram of the electricity supply device of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements. 
       FIG. 2  is a schematic diagram of an electricity supply device according to an embodiment of the invention. As shown in  FIG. 2 , an electricity supply device  2  includes two conductive substrates  22   a  and  22   b,  a chemical-electrical conversion module  24 , and a sealing structure  26 . The chemical-electrical conversion module  24  is disposed between the conductive substrates  22   a  and  22   b,  and includes two diffusion units  24   a  and  24   b  and a membrane electrode unit  24   c.  The diffusion unit  24   a  is disposed adjacent to the conductive substrate  22   a,  and the other diffusion unit  24   b  is disposed adjacent to the other conductive substrate  22   b.  The membrane electrode unit  24   c  is disposed between the diffusion units  24   a  and  24   b.  The sealing structure  26  includes a first protruding structure  261  and a second protruding structure  262 . The first protruding structure  261  is disposed against the conductive substrate  22   a,  and the diffusion unit  24   a  and the membrane electrode unit  24   c  are disposed against the inner side of the first protruding structure  261 . The second protruding structure  262  is disposed adjacent to the first protruding structure  261 , and is disposed against the other conductive unit  22   b  and the membrane electrode unit  24   c.  In this embodiment, only at least one end of the diffusion unit  24   a  and at least one end of the membrane electrode unit  24   c  disposed against the inner side can be enough to achieve the fixing purpose, and they do not have to totally against the inner side. 
       FIG. 3  is a schematic diagram showing the structure of the conductive substrate. Referring to both  FIG. 2  and  FIG. 3 , the conductive substrates  22   a  and  22   b  are used as the cathode conductive substrate and the anode conductive substrate, respectively. Regarding to their functions, the conductive substrate  22   a  has at least one reaction area Ra′ and at least two fluid transmission areas Ta′, and the conductive substrate  22   b  has at least one reaction area Rb′ and at least two fluid transmission areas Tb′. A part of the fluid transmission areas Ta′ and Tb′ can allow the fluid flowing into the reaction areas Ra′ and Rb′, and the other part of the fluid transmission areas Ta′ and Tb′ can allow the reacted fluid flowing out. Since the reaction areas Ra′ and Rb′ are the major chemical-electrical conversion areas, they are disposed corresponding to the chemical-electrically conversion module  24 . In addition, in order to increase the reaction rate of the fluids, the reaction areas Ra′ and Rb′ are further configured with several fluid channels Sa′ and Sb′, and the fluids can flow from the fluid transmission areas Ta′ and Tb′ to the wandered and high-density fluid channels Sa′ and Sb′. Thus, the fluids can homogeneously distributed to the entire reaction areas Ra′ and Rb′. To be noted the design of the fluid channels Sa′ and Sb′ can be various depending on different demands. Of course, the conductive substrates  22   a  and  22   b  may have only one surface that is configured with the fluid channels Sa′ and Sb′. In practice, multiple of electricity supply devices may be connected in serial or in parallel to provide the desired voltage or current, so that the major surfaces of the conductive substrate  22   a  or  22   b  can all be configured with the fluid channels Sa′ or Sb′. Thus, the conductive substrate  22   a  or  22   b  can be independently applied to two electricity supply devices. In this embodiment, the two major surfaces of the conductive substrate  22   a  (or  22   b ) are configured with the fluid channels Sa′ (or Sb′). 
     Since the conductive substrates  22   a  and  22   b  must have proper rigidity for supporting and protecting the components configured therein, proper flexibility for absorbing the structural stress during assembling, and good conductivity, they are usually made of the composition containing carbon and polymer. Of course, metal or alloy can also be used as the material of the conductive substrates  22   a  and  22   b.    
     Referring to  FIG. 2 , the chemical-electrical conversion module  24  includes two diffusion units  24   a  and  24   b,  and a membrane electrode unit  24   c.  The membrane electrode unit  24   c  is disposed between the diffusion units  24   a  and  24   b,  and is located corresponding to the reaction areas Ra′ and Rb′ of the conductive substrates  22   a  and  22   b.  In this embodiment, the membrane electrode unit  24   c  further includes two catalyze units  241  and  242 , and a proton exchanging unit  243 , which is disposed between the two catalyze units  241  and  242 . In other words, in one direction, the catalyze unit  241  and the diffusion unit  24   a  are stacked on the proton exchanging unit  243  in sequence, and, in the other direction, the catalyze unit  242  and the diffusion unit  24   b  are stacked on the proton exchanging unit  243  in sequence. 
     As mentioned above, when the conductive substrate  22   a  is used as the cathode substrate of the electricity supply device, the diffusion unit  24   a  and the catalyze unit  241  disposed between the conductive substrate  22   a  and the proton exchanging unit  243  are included in the general cathode. On the contrary, when the conductive substrate  22   a  is used as the anode substrate of the electricity supply device, the diffusion unit  24   a  and the catalyze unit  241  disposed between the conductive substrate  22   a  and the proton exchanging unit  243  are included in the general anode. 
       FIG. 4  is a cross-sectional diagram of the electricity supply device of  FIG. 2 . With reference to  FIG. 2  and  FIG. 4 , the sealing structure  26  includes a first protruding structure  261  and a second protruding structure  262 . The dimension of the first protruding structure  261  is larger than that of the second protruding structure  262 . In this case, the thickness M of the first protruding structure  261  is larger than the thickness δ2 of the second protruding structure  262 . 
     In more detailed, as shown in  FIG. 4 , the first protruding structure  261  is disposed against and between the conductive substrates  22   a  and  22   b,  and the diffusion unit  24   a  and the membrane electrode unit  24   c  are disposed against the inner side of the first protruding structure  261 . In other words, the conductive substrate  22   a,  the membrane electrode unit  24   c  and the first protruding structure  261  can configure an airtight space, so that the fluid flowing from the fluid transmission area Ta′ of the conductive substrate  22   a  can be sealed between the conductive substrate  22   a  and the membrane electrode unit  24   c,  thereby preventing the fluid leakage and the mixing with outside fluid. Similarly, the second protruding structure  262  is disposed against and between the conductive substrate  22   b  and the membrane electrode unit  24   c,  so that the conductive substrate  22   b,  the membrane electrode unit  24   c  and the second protruding structure  262  can configure an airtight space. Accordingly, the fluid flowing from the fluid transmission area Tb′ of the conductive substrate  22   b  can be sealed between the conductive substrate  22   b  and the membrane electrode unit  24   c , thereby preventing the fluid leakage and the mixing with outside fluid or the other fluid. 
     In this embodiment, the first protruding structure  261  and the second protruding structure  262  are integrally formed as one piece. In other words, the first protruding structure  261  and the second protruding structure  262  are not connected with each other. To be noted, depending on different designs or demands, the first protruding structure  261  and the second protruding structure  262  may be separated components. Besides the above-mentioned configuration of disposing the sealing structure  26  at the edges of the reaction areas Ra′ and Rb′ of the conductive substrates  22   a  and  22   b,  the sealing structure  26 , which includes the first and second protruding structures  261  and  262 , may be further disposed at the edges of the fluid transmission areas Ta′ and Tb′ of the conductive substrates  22   a  and  22   b  for preventing leakage when the fluid flows in to or out of the fluid transmission areas Ta′ and Tb′. To be noted, the first and second protruding structures  261  and  262  of the embodiment are both continuous structures, but at least one of them may be changed as a discontinuous structure according to different designs of, for example, the conductive substrates  22   a  and  22   b.    
     Regarding to the assembling procedure of the electricity supply device  2 , the sealing structure  26  is firstly disposed on the conductive substrate  22   b,  and then the diffusion unit  24   b,  the catalyze unit  242 , the proton exchanging unit  243 , the catalyze unit  241 , and the diffusion unit  24   a  are stacked thereon in order. After that, the other conductive substrate  22   a  is finally disposed thereon so as to finish the assembling of the electricity supply device  2 . In more detailed, the dimensions (or areas) of the diffusion unit  24   b  and catalyze unit  242  are usually similar to or slightly smaller than the enclosed area of the second protruding structure  262 . Thus, the diffusion unit  24   b  and catalyze unit  242  can be easily disposed inside the second protruding structure  262 . Besides, the dimension (or area) of the membrane electrode unit  24   c  is slightly larger than that of the diffusion unit  24   b,  and the membrane electrode unit  24   c  is disposed against both of the first and second protruding structures  261  and  262 . Similarly, the dimensions of the other catalyze unit  241  and diffusion unit  24   a  are usually similar to or slightly smaller than the enclosed area of the first protruding structure  261 , so that the catalyze unit  241  and diffusion unit  24   a  can be easily disposed inside the first protruding structure  261 . In this case, the diffusion unit  24   b  and catalyze unit  242  disposed at one side of the membrane electrode unit  24   c  can be sealed by the second protruding structure  262 , so that the fluid located in this area can be prevented from leaking or mixing with other fluid. Similarly, the catalyze unit  241  and diffusion unit  24   a  disposed at the other side of the membrane electrode unit  24   c  can be sealed by the first protruding structure  261 , so that the fluid located in this area can be prevented from leaking or mixing with other fluid. Of course, the above-mentioned two fluids located in the reaction areas Ra′ and Rb′ can be isolated by the membrane electrode unit  24   c.    
     In order to make the assembling procedure more simple and convenient, the conductive substrates  22   a  and  22   b  may further be configured with at least one positioning structure Ca and at least one positioning structure Cb, respective, which are disposed corresponding to the sealing structure  26 . Thus, the sealing structure  26  can be easily and accurately positioned on the proper location. For example, the positioning structures Ca and Cb can be recesses, protruding slots, or protrusions. In this embodiment, the positioning structures Ca and Cb are protruding slots, so that the sealing structure  26  can be positioned depending on the positioning structures Ca and Cb formed on the surfaces of the conductive substrates  22   a  and  22   b.  Except for the above-mentioned positioning structures Ca and Cb, each of the conductive substrates  22   a  and  22   b  may further be configured with at least one fixing structure (not shown), which is disposed corresponding to the sealing structure  26 , for fixing the sealing structure  26  on the conductive substrates  22   a  and  22   b.  Thus, the sealing structure  26  can be firmly connected with the conductive substrates  22   a  and  22   b  for avoiding sliding and shifting, which may influence the sealing effect. In this embodiment, the fixing structure can be a hook, a protruding slot or a protrusion. 
     To be noted, since the sealing structure  26  can be formed by flexible materials, such as silica gel, polyvinyl chloride (PVC), Polyethylene (PE), Polypropylene (PP), Polystyrene (PS), or their combinations, it can also absorb the assembling stress during the assembling procedure. Thus, the assembling stress can compress the sealing structure  26  to generate a deformation of the sealing structure  26 , which can enhance the sealing effect. In addition, since the flexible sealing structure  26  can absorb the extra assembling stress, the electricity supply device  2  can sustain larger external force. This can achieve the purpose of strengthening the structure of the electricity supply device  2 . 
     In summary, the electricity supply device of the invention has a sealing structure configured between two conductive substrates directly. This configuration can simplify the assembling procedure of the electricity supply device, and thus make the positioning of the membrane electrode module more accurate and easier. Moreover, it is cheaper to use only one sealing structure, which can still achieve good seaming effect for preventing the mixing and leakage of the cathode and anode fluids. Compared with the prior art, which uses two sealing bodies to seal the spaces located at two sides of the membrane electrode unit, respectively, and thus has the problems of misalignment and assembling, the sealing structure of the invention can be disposed on the conductive substrates in advance and then the other components are stacked thereon in order. Thus, the present invention can solve the problems of the prior art that uses two sealing bodies, and has the advantages of good sealing property and simpler assembling procedure. 
     Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the invention.