Abstract:
A power generator having a fuel cell and a fuel container in an enclosure with a pneumatic slide valve interposed between the fuel cell and the fuel container. The fuel cell may provide water vapor which goes to react with the fuel of the container and result in a production of hydrogen for the fuel cell. The valve may be connected to a pressure sensitive membrane that is linked to the valve such that when the pressure within the enclosure increases, the membrane will begin to move and close the valve to cut off the supply of water vapor to the fuel to reduce hydrogen production and consequently the pressure. With a reduction or stoppage of hydrogen production, the pressure may decrease and the membrane may begin to open the valve to let in water vapor to the fuel to make more hydrogen.

Description:
[0001]     The present invention may be related to U.S. patent application Ser. No. 11/247,435, filed Oct. 11, 2005; U.S. patent application Ser. No. 09/941,247, filed Aug. 28, 2001; U.S. patent application Ser. No. 10/780,827, filed Feb. 18, 2004; U.S. patent application Ser. No. 10/891,380, filed Jul. 14, 2004; U.S. patent application Ser. No. 10/850,673, filed May 21, 2004; U.S. patent application Ser. No. 10/750,581, filed Dec. 29, 2003; U.S. patent application Ser. No. 11/209,591, filed Aug. 22, 2005; U.S. patent application Ser. No. 11/270,848, filed Nov. 9, 2005; U.S. patent application Ser. No. 11/257,872, filed Oct. 25, 2005; and U.S. patent application Ser. No. 11/257,738, filed Oct. 25, 2005; all of which are hereby incorporated by reference. 
     
    
     BACKGROUND  
       [0002]     The present invention pertains to power generation devices and particularly to election power generation devices. More particularly, the invention pertains to fuel cells.  
       SUMMARY  
       [0003]     The invention is a space efficient energy per unit volume fuel cell having a pneumatic slide valve. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0004]      FIG. 1  is a sectional side view of a fuel cell;  
         [0005]      FIGS. 2   a ,  2   b  and  2   c  show three positions of a grid-like valve used in the fuel cell;  
         [0006]      FIG. 3  shows a cylindrical shaped fuel cell utilizing the valve of  FIGS. 2   a ,  2   b  and  2   c;    
         [0007]      FIGS. 4   a  and  4   b  show an illustrative implementation of a body structure of the fuel cell power generator assembly; and  
         [0008]      FIGS. 5   a  and  5   b  show a top portion for the illustrative of the body structure in  FIGS. 4   a  and  4   b.   
     
    
     DESCRIPTION  
       [0009]      FIG. 1  shows a fuel cell power generator or generation system or assembly  10  having a fuel container  11 , a mesh, perforated plate or layer, or grid, or the like, type of valve  12  connected to a pressure sensitive diaphragm  13 , and having a number of elements for a fuel cell  14  which are designed to provide electrical power. The elements may include a cathode electrode  16 , a cathode gas diffusion layer  15 , a membrane  17 , an anode gas diffusion layer  20 , and an anode electrode  18 . In the present example, the fuel cell may be on one side (or at the top in the Figure) of the block-like configuration  10  in  FIG. 1 . In the lower portion of the fuel cell assembly  10  may be a fuel container  11  which may contain a quantity of lithium alumina hydride or other cell fuel. A partial pressure may cause oxygen of the atmosphere to be drawn into a cavity  26 . There is not a partial pressure for nitrogen of the atmosphere. The atmosphere may be dry and draw in some of the water. The oxygen may come in on the cathode  16  side of the plurality of elements or cell  14 . Protons may move from the anode  18  to the cathode  16 . There may be a water vapor which has a partial pressure but the vapor is kept in by a membrane. Electrons may be stripped from the H 2  to result in protons going from the anode electrode  18  through an anode gas diffusion layer  20 , a membrane  17  and a cathode diffusion layer  15  to the cathode  16 . The electrons may constitute an electrical current that flows from the anode  18  through an impedance load  19  and to the cathode  16  where the electrons, protons and oxygen form a water vapor. Layer  17  may be a water vapor permeable electrolytic membrane. On the cathode may be an oxygen permeable, water vapor impermeable membrane. There may various approaches to the design of the fuel cell  14 .  
         [0010]     The valve  12  may be in place to regulate the water from going down, but not to keep the H 2  from going up, relative to the orientation of assembly  10  in  FIG. 1 . Water may be a generated product at the cathode. There may be a gas impermeable layer at the number of elements or cell  14  to prevent water or vapor from going through while permitting protons to move through the cell. When the water vapor encounters the fuel from the container  11 , hydrogen may be produced. The reaction may be stated as follows: 
 
LiAlH 4 +4H 2 O→4H 2 +Byproduct 
 
         [0011]      FIGS. 2   a ,  2   b  and  2   c  illustrate an operation of the valve in the present fuel cell design. The valve in  FIG. 2   a  may be open. A diaphragm  13  may move the valve  12  to an open position and, on the other hand, move the valve  12  to a closed position as shown in  FIG. 2   c . The valve may have a partially open position as identified in  FIG. 2   b . Valve  12  may have two mesh-, grid- or plate-like parts  21  and  22 . These parts may be of other forms or design to effect the operation described here. Part  21  may be stationary relative to the fuel cell assembly or system  10 . Part  22  may be positioned on or adjacent to part  21 . These parts  21  and  22  may be plates or the like with numerous openings  23  in them. The openings may be in the form of, for instance, small rectangular shapes laid out in a symmetrical pattern in both plates  21  and  22 . With plate  22  overlaid on plate  21 , the openings  23  may be aligned such that matter may flow through the pair of plates  21  and  22 , as shown in  FIG. 2   a . Plate  22  may be moved left relative to plate  21  and the openings  23  will become partially closed as shown in  FIG. 2   b . If plate  22  is further moved left, the openings  23  may be closed in that portions of plates  21  and  22  overlap each other&#39;s openings, as shown in  FIG. 2   c.    
         [0012]     Even though the valve  12  is described in terms of two plates or the like, more than two plates or the like may be implemented in valve  12 . The principle of operation may be the same except there may be various partial overlaps of the more than two plates for perhaps more precise control of a flow through the valve  12 . A valve having more than two plates or the like may be applicable to the configuration or assembly  30  of  FIG. 3  or to other kinds of configurations or assemblies.  
         [0013]     Plate  22  may be moved by a diaphragm  13  which is pressure sensitive. If pressure of matter in the portion of the cell assembly in the volume  26  proximate to plate  22  increases, as shown in  FIGS. 2   a ,  2   b  and  2   c , then the diaphragm  13  may bulge out from the chamber volume  26  proximate to plate  22 . Attached at about a center  24  of diaphragm  13  may be a linkage  25  that is attached to plate  22 . When bulging out at the center  24  (to the left in the Figures) because of pressure, then the linkage  25  may likewise pull plate  22  to the left (in the Figures) to reduce the flow of matter or gas through the plates in response to the increased pressure. If the pressure increases even more, then diaphragm  13  may expand further out to its stop thereby causing plate  22  to have its non-open areas overlap plate  21  openings  23 , and plate  21  to have its non-open areas overlap plate  22  openings and effectively stop the flow of matter (e.g., water vapor) through plates  21  and  22 . As the pressure decreases in the chamber  26  proximate to plate  22 , then diaphragm  13  may begin returning to a less bulged state and via the linkage  25  push plate  22  so that a part of the openings  23  of both plates  21  and  22  are uncovered or unclosed. Further reduction of the pressure in chamber  26  may result in diaphragm  13  returning to its initial open position thereby moving plate  22  so that the openings  23  of plates  21  and  22  are aligned such that none of the openings  23  in the plates are effectively obscured by either plate. Again, as the chamber  26  pressure increases, the valve  12  begins to close, and as the chamber  26  pressure decreases, the valve  12  begins to open. Thus, the amount of flow through the valve  12  may be determined by the chamber  26  pressure. This approach may provide a regulation of the flow or volume of the gas from chamber  26  through the valve. This operation may be implemented with a valve  12  having more than two plates or components for controlling a flow of a fluid or material. A fluid may be a gas or a liquid.  
         [0014]     The valve mechanism described in  FIGS. 2   a ,  2   b  and  2   c  may be designed into a cylindrical fuel cell device  30  as shown in  FIG. 3 . The mechanism may also be designed into a fuel cell generator assembly having some other shape. In  FIG. 3 , the fuel volume or supply may be in the center of the cylinder. Between the cell  14  and the fuel supply container or chamber  11  may be a cylindrical slide valve  12 . The valve may be two cylindrical sleeves of grid, mesh, perforated material, or the like, that are concentric and adjacent to each other. The parts  21  and  22  of the cylindrical valve may slide relative to each other to open and close the valve  12  (like the parts  21  and  22  in  FIGS. 2   a - 2   c ). On the outside of the circumference slide valve  12  may be a fuel cell or cells  14  (similar to the fuel cell  14  of  FIG. 1 ).  
         [0015]     A diaphragm  13  for operating the cylindrical valve  12  may be situated at the end of a cylindrical chamber  26  and linked to a part  21  or  22  of valve  12 . Diaphragm  13  may be responsive to pressure in chamber  26  in that if the pressure increases, one of the valve  12  parts  21  and  22  will be moved relative to the other by the linked diaphragm  13  to close the valve  12 , and if the pressure decreases, then the valve  12  will be at least gradually opened, thereby monitoring an amount of vapor flow to the fuel cell or cells  14 . The same design and operation of the present illustrative examples of fuel cell assemblies  10  and  30  may apply to fuel cell assemblies of other shapes.  
         [0016]     The chamber  26  of the fuel cell assembly  10 ,  30  may be sealed and fuel may added through an opening having a removable cover  27  adjacent or part of the fuel chamber  11 , which seals chamber  26  when the cover is in place.  
         [0017]     The fuel cell  14  may have an electrolytic membrane  17  positioned between a negative electrode or cathode  16  and a positive electrode or anode  18 . A hydrogen fuel (i.e., hydrogen gas) may be channeled through flow field plates  21  and  22  to the anode  18 , while oxygen is channeled to the cathode  16  of the fuel cell. At the anode  18 , the hydrogen may be split into positive hydrogen ions (protons) and negative electrons. The electrolytic membrane may allow only protons to pass through it to the cathode  16 . The electrons instead may travel as a current via an external circuit  19  to the cathode  16 . At the cathode  16 , the electrons and the protons may combine with oxygen to form water molecules.  
         [0018]     Once water is formed as a byproduct of an oxygen-hydrogen reaction at the fuel cell  14 , the produced water may passively diffuse back through the fuel cell into a cavity  26  to the fuel chamber or container  11 . Within the cavity  26  on the anode  18  side of the fuel cell  14 , a relatively low humidity region may exist due to a moisture absorbing nature of the fuel substance in fuel container  11 . Thus, the water retention at the cathode  16  may generate a moisture concentration gradient and a gas pressure differential which causes water molecules to diffuse back through the fuel cell  14  into cavity  26  and to fuel chamber  12  in the form of water vapor. This water vapor may react with the fuel of container  11  and generate hydrogen gas. The generated hydrogen gas may then pass through cavity  26  and to the fuel cell anode  18  where it can react with oxygen to once again generate water molecules. This cycle may continue until all of the fuel in chamber  11  is consumed.  
         [0019]     The fuel cell power generator system  10 ,  30  may utilize the valve  12  for regulating the passage of water vapor from the fuel cell  14  to the container  11  and regulating the production of hydrogen gas from the fuel container  11 . Valve  12  may be positioned in the cavity  26  between the fuel container  11  and the fuel cell  14 . Valve  12  may be a pneumatic valve that is controlled by a gas pressure in the cavity  26 , where it is pneumatically adjusted to control a conveyance of water vapor to the fuel container  11 . Valve  12  may be a slidable plate  22  with openings adjacent to another plate  21  having similar openings  23  which overlap each other upon closing or opening the valve  12 , which is described at another place of this description. When the valve  12  is in a closed position, it may prevent water vapor from reaching the fuel container  11 . Alternatively, when valve  12  is in an open position, it may allow water vapor to reach the fuel container  11  and allow generated hydrogen gas to reach the fuel cell  14 . The singular reference to a fuel cell  14  in this description may also mean reference to more than one fuel cell.  
         [0020]     The actuation of valve  12  may be controlled by an internal pressure exerted on the diaphragm  13 . As the internal gas pressure of the cavity  26  rises due to the generation of hydrogen gas, the diaphragm  13  may bend or push out slightly. This may cause the linkage  25  to pull slidable valve plate  22  and move it relative to plate  21 , closing the valve  12  and preventing the flow of additional water vapor to the fuel container  11 . With valve  12  closed, the hydrogen production may cease. This situation may also prevent the internal gas pressure from rising further. As hydrogen is consumed, such as by fuel cell  14 , the internal gas pressure may drop, allowing the membrane  13  to return to a more relaxed state and open the valve  12 . The sliding valve  12  plate  22  may move about one millimeter from fully open to fully closed. It may take about 4 psi (27 kPa) to 6 psi (42 kPa) pressure on the membrane or diaphragm  13  to fully close the valve  12 . Accordingly, hydrogen gas may automatically be produced at a rate at which it is consumed.  
         [0021]      FIGS. 4   a  and  4   b  show an illustrative implementation of a body structure for the fuel cell system or assembly  10 . Adjacent to the valve  12  may be a window frame like structure  31 . Structure  31  may provide strength to the valve and the assembly. Valve  12  may have two or more grids where one or more grids are moveable relative to the other grid or grids for opening and closing the valve. The moveable grids may be connected to the pressure sensitive diaphragm  13 . Adjacent to the valve  12  may be the chamber or cavity  26 . The fuel container or chamber  11  may be adjacent to cavity or chamber  26 . At the exterior portion of the fuel container or chamber  11  may be a cover  27 . Cover  27  may seal the container or chamber  11  from the ambient environment. Cover  27  may be removed, as shown in  FIG. 4   b , for adding fuel to the container or chamber  11 . Situated at a level  32  proximate to structure  31  and valve  12 , fuel cell  14  components may be placed.  
         [0022]     Electrode  18  may be a gold coating on top of the stationary portion or plate  21  of valve  12 . Electrode  16  may be a coating on the bottom side of a top structure  28  that may be placed on the assembly  10 , as shown in  FIGS. 5   a  and  5   b . Structure  28  may have grid or mesh openings that are aligned with those of plate  21 . Layers or components  15 ,  17  and  20  may be situated between electrodes  16  and  18 . Other components or layers may be situated between, or on top or bottom of the electrodes  16  and  18 , respectively.  
         [0023]     In the present specification, some of the matter may be of a hypothetical or prophetic nature although stated in another manner or tense.  
         [0024]     Although the invention has been described with respect to at least one illustrative example, many variations and modifications will become apparent to those skilled in the art upon reading the present specification. It is therefore the intention that the appended claims be interpreted as broadly as possible in view of the prior art to include all such variations and modifications.