Abstract:
A fuel cell based power generator exhibits a plurality of different power outputs. A selection structure carried by the generator facilitates specification of a desired output power.

Description:
FIELD 
     The invention pertains to fuel cell based power generators. More particularly, the invention pertains to such power generators which can provide a plurality of electrical outputs, one of which is selectable. 
     BACKGROUND 
     Batteries represent a substantial type of business whether for original equipment use or as replacements. Fuel cells may provide an alternative source of electrical energy for certain types of products. However, while batteries can provide a wide range of power levels, and are sold based on capacity, fuel cell based power generators can only provide a relatively narrow range of power levels. This potentially results in a different type of sales model based on power capability and energy capacity. 
     However given the potential size of the battery market it would be desirable to be able to configure fuel cell based power generators such that they more readily correspond to the current sales model as to how batteries are sold. This has the advantage of potentially reduced market fragmentation and increased acceptance and adoption of fuel cell technologies. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates one form of a variable power generator in accordance with the invention; 
         FIG. 1B  illustrates a variation on the generator of  FIG. 1A ; 
         FIG. 2A  is a front elevational view of another variable power fuel cell based generator in accordance with the invention; 
         FIG. 2B  is a top plan view of the generator of  FIG. 2A ; 
         FIG. 2C  is a side sectional view taken along plane  2 C- 2 C of  FIG. 2A ; and 
         FIG. 3  illustrates an electrical unit of a type which could be energized by power generators in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION 
     While embodiments of this invention can take many different forms, specific embodiments thereof are shown in the drawings and will be described herein in detail with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention, as well as the best mode of practicing same, and is not intended to limit the invention to the specific embodiment illustrated. 
     Embodiments of the present invention include power generators with output power selection structures. For example, in one aspect of the invention, user actuated switches or seals can be provided. The switches or seals mechanically open or seal portions of an array of fuel cell anodes, for example, from a hydrogen source or cathodes from the ambient. The seals prevent their respective cells from contributing to power generation. Advantageously, power generators in accordance with the invention, which make available selectable power outputs, will reduce the number of devices required to energize the multitude of different electronic devices currently available. 
     It will be understood that the selection structures can be implemented in a variety of configurations without departing from the spirit and scope of the present invention. For example, the switches or seals can be selected, removed or opened manually or automatically. 
     In another aspect of the invention, variable power generators in accordance with the invention can be automatically configured for use with a selected electrical unit when inserted into the respective unit. The appropriate output power can be selected by mechanically moving a switch or a valve. Alternately, a seal or foil can be torn or removed in the process of inserting the generator into the respective electrical unit. 
     In yet another aspect of the invention a plurality of fuel cells can be connected in series to achieve a desired output voltage. For example, five or six cells can be connected in series to achieve an output voltage in a range of three to four volts. A plurality of series configurations can be interconnected in parallel to provide additional output current at the common voltage. One plurality or another can be selected by means of an actuated switch, valve or seal which can be actuated or broken to provide the desired output power. Those switches or seals which have not been actuated or disturbed do not contribute to generation of electrical power and do not permeate hydrogen into the ambient atmosphere. 
     Exemplary configurations include five or six cells in series which can produce an output power of 10 mW. A plurality of such configurations, five or six could be coupled in parallel and provide 50 to 60 mW output. Alternately, each series configuration could produce different output power level. For example, configurations could be provided to produce 5, 10, 10, 25, 25, 50 and 100 mW. In this configuration, power levels from 100 to 200 mW can be provided in 5 mW increments. Other configurations and power output levels come within the spirit and scope of the invention. 
     In yet another aspect of the invention, self-configuring units can be provided having multiple moveable pins or terminations which can be actuated by an electronic device. For example, each pin or actuator on the generator can be connected to a valve which when activated exposes the respective fuel cell cathode to the ambient, or the fuel cell anode to hydrogen. The pin or moveable member can be activated by the respective electronic device. Inserting the generator into the device actuates the valves associated with the desired output power. 
       FIGS. 1A and 1B  illustrate two embodiments of the present invention,  10  and  20 . Each of the embodiments incorporates a generator having a housing  12 ,  22  respectively. The dimensions and shape of the respective housing  12 ,  22  are not limitations of the present invention. They can be dictated for example by the respective electronic units which are to be energized by the respective generator. 
     Each of generators  10 ,  20  incorporates a plurality of interconnected fuel cells such as  14   a, b, c, d  and  16   a, b, c, d . One of the combinations of fuel cells  14 - i ,  16 - i  can be selected in each of the generators  10 ,  20  depending on the application. As noted above, by combining several series connected fuel cells in parallel different power outputs can be provided at a common voltage such as 3 to 4 volts. 
     Cell combinations  14   a ,  16   a  for example can provide 100 mW output. Similarly combinations  14   c  and  16   c  can provide 33 mW outputs. 
     In accordance with the invention, a particular fuel cell configuration can be selected either manually or automatically, as discussed subsequently, by displacing a selection member such as  14   a - 1 ,  14   b - 1 ,  14   c - 1 , and  14   d - 1 . Displacement in any convenient direction relative to the housing  12 . One of the fuel cell combinations  14   i  can be manually or automatically selected by displacing one of the members such as  14   a - 1  thereby exposing either a respective cathode or anode to the ambient or hydrogen. Other fuel cell combinations in the generator do not contribute to the power output of the selected cell combination. 
     The selection mechanism of the generator  20  incorporates a plurality of removable or piercable seals or coverings, which could be formed of foil or membrane or the like all without limitation  16   a - 1 ,  16   b - 1 ,  16   c - 1 , and  16   d - 1 . Analogously to the selection process of the generator  10 , one of the covers or foils is pierced, torn or removed to activate a fuel cell combination. For example piercing or removing the respective cover of fuel cell can expose the respective cathodes to the ambient. Alternately, the respective anodes could be exposed to hydrogen. 
       FIGS. 2A-2C  illustrate a self-configuring form of generator  30  in accordance with the invention. The generator  30 , analogously to the generator  10 , incorporates a plurality of moveable or operable selection members such as  34   a - 1 ,  34   b - 1 ,  34   c - 1  and  34   d - 1 . The associated fuel cell combinations such as  34   a, b, c , and  d  can be selected by deflecting or moving the respective member or pin  34   a - 1 ,  b - 1 ,  c - 1  and  d - 1 . This can be accomplished by inserting the housing  32  into the respective electronic unit which in turn then deflects the appropriate valve, pin or selecting member to meet its requirements. Alternately, a respective cover or seal can be opened. Output power can be extracted by terminals  36 . 
     As illustrated in  FIG. 2C , the cell configuration  34   a  can include a common fuel supply  40   a , a slidable valve or cover  38   a  which is coupled to deflect the member or pin  34   a - 1 . Displacing the valve or cover  38   a  exposes the cathode of the cells  34   a  to the ambient. Alternately, the anodes can be exposed to the hydrogen fuel  40   a.    
       FIG. 3  illustrates a respective electronic unit  50  with which a self-configuring generator such as the generator  30  can be used. A cavity  50 - 1  incorporates a selection member  50 - 2  which engages one of the pins or valve elements  34   a - 1 ,  b - 1 ,  c - 1 , or  d - 1  of generator  30  when the generator is inserted into the cavity  50 - 1 . In response to having selected a desired output power and thereby activating a selective plurality of fuel cells, current at a predetermined voltage can be coupled via electrodes  36  to terminals  50 - 3  of the electrical unit  50  thereby energizing same. 
     It will be understood that a variety of selection members, corresponding to the member  50 - 2  can be incorporated into selected electrical units to produce different motions or displacements, or close an electrical circuit as the respective generator such as a generator  30  as being inserted. Exemplary configurations can include electrically activated valves (solenoid activated, electro-statically activated or the like without limitation) which are triggered as the generator is being inserted into a respective cavity. Alternately, electrical energy, for example a heated member adjacent to or extending through a cover or seal can be used to perforate same and select a generator. RF heating could also be used. All such configurations come within the spirit and scope of the present invention. 
     In yet another aspect of the invention, as an alternate to being able to select a power level appropriate for an electronic device, an output voltage and/current could also be automatically selected, based on the characteristics of the device, as the generator is being coupled to a respective electronic device by selectively coupling cells in series and/or parallel. As those of skill in the art will understand, the exact details of such selection structures are not limitations of the present invention. 
     From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.