Power generator with a pneumatic slide valve

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.

BACKGROUND

The present invention pertains to power generation devices and particularly to election power generation devices. More particularly, the invention pertains to fuel cells.

SUMMARY

The invention is a space efficient energy per unit volume fuel cell having a pneumatic slide valve.

DESCRIPTION

FIG. 1shows a fuel cell power generator or generation system or assembly10having a fuel container11, a mesh, perforated plate or layer, or grid, or the like, type of valve12connected to a pressure sensitive diaphragm13, and having a number of elements for a fuel cell14which are designed to provide electrical power. The elements may include a cathode electrode16, a cathode gas diffusion layer15, a membrane17, an anode gas diffusion layer20, and an anode electrode18. In the present example, the fuel cell may be on one side (or at the top in the Figure) of the block-like configuration10inFIG. 1. In the lower portion of the fuel cell assembly10may be a fuel container11which 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 cavity26. 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 cathode16side of the plurality of elements or cell14. Protons may move from the anode18to the cathode16. 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 H2to result in protons going from the anode electrode18through an anode gas diffusion layer20, a membrane17and a cathode diffusion layer15to the cathode16. The electrons may constitute an electrical current that flows from the anode18through an impedance load19and to the cathode16where the electrons, protons and oxygen form a water vapor. Layer17may 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 cell14.

The valve12may be in place to regulate the water from going down, but not to keep the H2from going up, relative to the orientation of assembly10inFIG. 1. Water may be a generated product at the cathode. There may be a gas impermeable layer at the number of elements or cell14to prevent water or vapor from going through while permitting protons to move through the cell. When the water vapor encounters the fuel from the container11, hydrogen may be produced. The reaction may be stated as follows:
LiAlH4+4H2O→4H2+Byproduct

FIGS. 2a,2band2cillustrate an operation of the valve in the present fuel cell design. The valve inFIG. 2amay be open. A diaphragm13may move the valve12to an open position and, on the other hand, move the valve12to a closed position as shown inFIG. 2c. The valve may have a partially open position as identified inFIG. 2b. Valve12may have two mesh-, grid- or plate-like parts21and22. These parts may be of other forms or design to effect the operation described here. Part21may be stationary relative to the fuel cell assembly or system10. Part22may be positioned on or adjacent to part21. These parts21and22may be plates or the like with numerous openings23in them. The openings may be in the form of, for instance, small rectangular shapes laid out in a symmetrical pattern in both plates21and22. With plate22overlaid on plate21, the openings23may be aligned such that matter may flow through the pair of plates21and22, as shown inFIG. 2a. Plate22may be moved left relative to plate21and the openings23will become partially closed as shown inFIG. 2b. If plate22is further moved left, the openings23may be closed in that portions of plates21and22overlap each other's openings, as shown inFIG. 2c.

Even though the valve12is described in terms of two plates or the like, more than two plates or the like may be implemented in valve12. 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 valve12. A valve having more than two plates or the like may be applicable to the configuration or assembly30ofFIG. 3or to other kinds of configurations or assemblies.

Plate22may be moved by a diaphragm13which is pressure sensitive. If pressure of matter in the portion of the cell assembly in the volume26proximate to plate22increases, as shown inFIGS. 2a,2band2c, then the diaphragm13may bulge out from the chamber volume26proximate to plate22. Attached at about a center24of diaphragm13may be a linkage25that is attached to plate22. When bulging out at the center24(to the left in the Figures) because of pressure, then the linkage25may likewise pull plate22to 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 diaphragm13may expand further out to its stop thereby causing plate22to have its non-open areas overlap plate21openings23, and plate21to have its non-open areas overlap plate22openings and effectively stop the flow of matter (e.g., water vapor) through plates21and22. As the pressure decreases in the chamber26proximate to plate22, then diaphragm13may begin returning to a less bulged state and via the linkage25push plate22so that a part of the openings23of both plates21and22are uncovered or unclosed. Further reduction of the pressure in chamber26may result in diaphragm13returning to its initial open position thereby moving plate22so that the openings23of plates21and22are aligned such that none of the openings23in the plates are effectively obscured by either plate. Again, as the chamber26pressure increases, the valve12begins to close, and as the chamber26pressure decreases, the valve12begins to open. Thus, the amount of flow through the valve12may be determined by the chamber26pressure. This approach may provide a regulation of the flow or volume of the gas from chamber26through the valve. This operation may be implemented with a valve12having more than two plates or components for controlling a flow of a fluid or material. A fluid may be a gas or a liquid.

The valve mechanism described inFIGS. 2a,2band2cmay be designed into a cylindrical fuel cell device30as shown inFIG. 3. The mechanism may also be designed into a fuel cell generator assembly having some other shape. InFIG. 3, the fuel volume or supply may be in the center of the cylinder. Between the cell14and the fuel supply container or chamber11may be a cylindrical slide valve12. The valve may be two cylindrical sleeves of grid, mesh, perforated material, or the like, that are concentric and adjacent to each other. The parts21and22of the cylindrical valve may slide relative to each other to open and close the valve12(like the parts21and22inFIGS. 2a-2c). On the outside of the circumference slide valve12may be a fuel cell or cells14(similar to the fuel cell14ofFIG. 1).

A diaphragm13for operating the cylindrical valve12may be situated at the end of a cylindrical chamber26and linked to a part21or22of valve12. Diaphragm13may be responsive to pressure in chamber26in that if the pressure increases, one of the valve12parts21and22will be moved relative to the other by the linked diaphragm13to close the valve12, and if the pressure decreases, then the valve12will be at least gradually opened, thereby monitoring an amount of vapor flow to the fuel cell or cells14. The same design and operation of the present illustrative examples of fuel cell assemblies10and30may apply to fuel cell assemblies of other shapes.

The chamber26of the fuel cell assembly10,30may be sealed and fuel may added through an opening having a removable cover27adjacent or part of the fuel chamber11, which seals chamber26when the cover is in place.

The fuel cell14may have an electrolytic membrane17positioned between a negative electrode or cathode16and a positive electrode or anode18. A hydrogen fuel (i.e., hydrogen gas) may be channeled through flow field plates21and22to the anode18, while oxygen is channeled to the cathode16of the fuel cell. At the anode18, 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 cathode16. The electrons instead may travel as a current via an external circuit19to the cathode16. At the cathode16, the electrons and the protons may combine with oxygen to form water molecules.

Once water is formed as a byproduct of an oxygen-hydrogen reaction at the fuel cell14, the produced water may passively diffuse back through the fuel cell into a cavity26to the fuel chamber or container11. Within the cavity26on the anode18side of the fuel cell14, a relatively low humidity region may exist due to a moisture absorbing nature of the fuel substance in fuel container11. Thus, the water retention at the cathode16may generate a moisture concentration gradient and a gas pressure differential which causes water molecules to diffuse back through the fuel cell14into cavity26and to fuel chamber12in the form of water vapor. This water vapor may react with the fuel of container11and generate hydrogen gas. The generated hydrogen gas may then pass through cavity26and to the fuel cell anode18where it can react with oxygen to once again generate water molecules. This cycle may continue until all of the fuel in chamber11is consumed.

The fuel cell power generator system10,30may utilize the valve12for regulating the passage of water vapor from the fuel cell14to the container11and regulating the production of hydrogen gas from the fuel container11. Valve12may be positioned in the cavity26between the fuel container11and the fuel cell14. Valve12may be a pneumatic valve that is controlled by a gas pressure in the cavity26, where it is pneumatically adjusted to control a conveyance of water vapor to the fuel container11. Valve12may be a slidable plate22with openings adjacent to another plate21having similar openings23which overlap each other upon closing or opening the valve12, which is described at another place of this description. When the valve12is in a closed position, it may prevent water vapor from reaching the fuel container11. Alternatively, when valve12is in an open position, it may allow water vapor to reach the fuel container11and allow generated hydrogen gas to reach the fuel cell14. The singular reference to a fuel cell14in this description may also mean reference to more than one fuel cell.

The actuation of valve12may be controlled by an internal pressure exerted on the diaphragm13. As the internal gas pressure of the cavity26rises due to the generation of hydrogen gas, the diaphragm13may bend or push out slightly. This may cause the linkage25to pull slidable valve plate22and move it relative to plate21, closing the valve12and preventing the flow of additional water vapor to the fuel container11. With valve12closed, 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 cell14, the internal gas pressure may drop, allowing the membrane13to return to a more relaxed state and open the valve12. The sliding valve12plate22may 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 diaphragm13to fully close the valve12. Accordingly, hydrogen gas may automatically be produced at a rate at which it is consumed.

FIGS. 4aand4bshow an illustrative implementation of a body structure for the fuel cell system or assembly10. Adjacent to the valve12may be a window frame like structure31. Structure31may provide strength to the valve and the assembly. Valve12may 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 diaphragm13. Adjacent to the valve12may be the chamber or cavity26. The fuel container or chamber11may be adjacent to cavity or chamber26. At the exterior portion of the fuel container or chamber11may be a cover27. Cover27may seal the container or chamber11from the ambient environment. Cover27may be removed, as shown inFIG. 4b, for adding fuel to the container or chamber11. Situated at a level32proximate to structure31and valve12, fuel cell14components may be placed.

Electrode18may be a gold coating on top of the stationary portion or plate21of valve12. Electrode16may be a coating on the bottom side of a top structure28that may be placed on the assembly10, as shown inFIGS. 5aand5b. Structure28may have grid or mesh openings that are aligned with those of plate21. Layers or components15,17and20may be situated between electrodes16and18. Other components or layers may be situated between, or on top or bottom of the electrodes16and18, respectively.

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.