Abstract:
Automated systems and methods remove water from a fuel cell powered vehicle and eliminate the need for one or more separate steps to discharge the water. The water may be simultaneously drained or discharged from the vehicle holding tank while the fuel cell powered vehicle is being refueled.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT CONCERNING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     FIELD OF THE INVENTION 
     The invention relates to the field of fuel cell powered devices, and more specifically to automatically discharging fuel cell generated water from a holding tank on-board a fuel cell powered vehicle. 
     BACKGROUND OF THE INVENTION 
     Fuel cells are well known and are commonly used to produce electrical energy by means of electrochemical reactions. The fuel cell produces electricity by bringing a fuel such as hydrogen, methanol, hydrocarbons, or natural gas, for example, and an oxidant, typically air, into contact with two suitable electrodes and an electrolyte. 
     When hydrogen is used as the fuel and air as the oxidant, the use of fuel cells in power generation offers potential environmental benefits because the by-products of such a reaction are heat and water. When other fuels and oxidants are employed, the by-products will accordingly differ. When compared to more conventional power generation equipment, e.g., fossil fuels or nuclear activity, fuel cells have advantages of less pollutant, lower noise generated, increased energy density and higher energy conversion efficiency. Fuel cell power generation is proportional to the consumption rate of the fuel and oxidant. 
     Fuel cells can be used in a wide variety of devices where electricity is required, including portable electronic products, home-use or plant-use power generation systems, large-size power generation systems, military equipment, the space industry, and vehicles such as automotive, truck, and bus power systems, as non-limiting examples. 
     A common problem that has to be addressed with fuel cell powered vehicles is the removal of water generated by the chemical reactions within the fuel cell. In operation, fuel cells produce an appreciable amount of water. This water needs to be removed from the vehicle in some way, and the removal presents an extra amount of effort and additional steps of work on the part of the vehicle operator. 
     Traditionally, the water or water vapors has been simply vented to the ambient environment outside the fuel cell system or allowed to drain or drip on the floor. These disposal methods may not be desirable depending upon the actual application of the fuel cell system. The water may also be stored in a holding tank for manual disposal later. 
     In the above examples, storage of the water in a storage tank for manual discharge at some later point may be preferred, yet manual discharge of the water presents an additional operational complication to the operation of the fuel cell powered vehicle. Vehicles equipped with other power sources do not require a comparable water discharge operation in addition to the operation of fueling. The additional water discharge step takes time and increases the amount of activity necessary to keep the fuel cell powered vehicle operational. Lack of removal of the water may also result in functional difficulties of the fuel cell or eventual curtailment of the use of the fuel cell powered vehicle until the water can be manually discharged. 
     It would therefore be desirable to incorporate automated systems and methods to remove the water and to eliminate the need for one or more separate steps to discharge the water from the vehicle. The water may be automatically drained or discharged from the holding tank while the fuel cell powered vehicle is being refueled. 
     SUMMARY OF THE INVENTION 
     The invention overcomes the drawbacks of the previous fuel cell powered vehicles by eliminating the need for one or more separate steps required to manually discharge the water from an on-board water holding tank. 
     The invention provides systems and methods of operating a fuel cell powered vehicle in which discharge of accumulated water from the water holding tank may be automated before, during, or after the fueling process. No specific additional actions are required on the part of the vehicle operator. 
     The automatic discharge operation may be self-timing, i.e., providing water capacity and drain time commensurate with the amount of time the vehicle is re-fueled and/or the amount of fuel supplied to the vehicle during refueling. Properly scaled, at least enough water will be drained from the vehicle holding tank as the replacement fuel will subsequently generate. 
     In one embodiment, an automatic drain system and method is provided that uses a pump within the fueling station (or alternatively the fuel cell system), wherein the nozzle used to refill the fuel tank on-board the vehicle also provides a suction, e.g., created by the pump, to draw the accumulated water from the vehicle holding tank and to an external holding tank or an appropriate drain. 
     In another embodiment, an automatic drain system and method is provided to open a drain valve on the water holding tank when a sensing system detects that fueling is in process, or that the lift truck is connected to a fueling nozzle. Actuation of the water drain valve at that time causes the water to drain into an appropriate catch basin or drain formed at or as part of the fueling station floor area. 
     In yet another embodiment, a method of removing water from a fuel cell powered vehicle comprises: collecting the water from the fuel cell in a holding tank, the fuel cell and holding tank disposed on the lift truck; coupling a fueling nozzle to a fueling fitting disposed on the lift truck, the fueling fitting being in fluid communication with the holding tank and a fuel tank; and after coupling the fueling nozzle to the fueling fitting, automatically discharging the water from the holding tank. 
     Yet another embodiment provides systems and methods comprising a fuel cell powered vehicle. A fuel cell is disposed on the vehicle and adapted to produce usable electrical energy and water. A fuel tank and a holding tank are also disposed on the vehicle. The fuel tank contains a supply of fuel for the fuel cell and the holding tank holds the water. A holding tank drain valve is in fluid communication with the holding tank. A fueling fitting is disposed on the vehicle and adapted to sealingly couple to a mating fueling nozzle. The vehicle also includes a sensing system on or near the fueling fitting, the sensing system adapted to sense at least one of the fueling nozzle coupled to the fueling fitting and fueling in process, and to open the holding tank drain valve to allow the water to drain when at least one of the fueling nozzle coupled to the fueling fitting and fueling in process is sensed. 
     In some embodiments, the sensing system is adapted to close the holding tank drain valve when at least one of the fueling nozzle coupled to the fueling fitting and fueling in process is not sensed. The drain valve may be sized and configured to discharge an amount of water during refueling that is greater than or equal to an amount of water that would be generated by the fuel cell when the fuel cell consumes the fuel that is supplied to the vehicle during the refueling. 
     In some embodiments, the fuel tank is sized and configured to receive a maximum supply of fuel, the maximum supply of fuel capable of generating an amount of water just less than or equal to a maximum capacity of the holding tank. 
     In some embodiments, a dual port fitting is disposed on the vehicle and is adapted to sealingly couple to a mating dual port fueling nozzle. A fueling conduit in fluid communication with the fuel tank and the dual port fitting, and a water conduit in fluid communication with the holding tank and the dual port fitting. A pumping system may be included to transfer the water from the holding tank through the water conduit and through the dual port fitting and through the dual port fuel nozzle. The fueling conduit and the water conduit are at least one of juxtaposed and coaxial at the dual port fitting. 
     In some embodiments, the dual port fitting comprises a fuel port and a water port. The dual port fitting is adapted to simultaneously receive fuel from the fueling nozzle to fill the fuel tank and to discharge water from the holding tank. 
     In some embodiments, the dual port fueling nozzle is in fluid flow communication with a fueling station, the fueling station including a fuel storage tank and at least one of a fueling station water storage tank and a drain. The fueling station may include a pumping system adapted to transfer the water from the holding tank through the water conduit and through the dual port fitting and through the dual port fuel nozzle and to at least one of the fueling station water storage tank and the drain. 
     In yet another embodiment, a method of removing water from a fuel cell powered vehicle comprises: collecting the water from the fuel cell in a holding tank, the fuel cell and holding tank disposed on the vehicle, coupling a fueling nozzle to a fueling fitting disposed on the vehicle, the fueling fitting being in fluid communication with the holding tank and a fuel tank, sensing at least one of the fueling nozzle coupled to the fueling fitting and fueling in process, and filling the fuel tank with fuel while simultaneously discharging the water from the holding tank. 
     In some embodiments, the fueling nozzle comprises a two port fueling nozzle and the fueling fitting comprises a mating two port fueling fitting. The method further includes coupling the two port fueling nozzle to the two port fueling fitting and discharging the water from the holding tank through the two port fueling fitting and through the two port fueling nozzle. 
     In some embodiments, the two port fueling nozzle is in fluid communication with a fueling station, and the fueling station comprises a fuel storage tank and at least one of a water storage tank and a floor drain. The method further includes discharging the water from the holding tank through the two port fueling fitting and through the two port fueling nozzle and to at least one of the water storage tank and the floor drain, and simultaneously, refueling the vehicle by transferring fuel from the fuel storage tank through the two port fueling nozzle and through the two port fuel fitting and into a fuel tank on-board the vehicle. 
     In some embodiments, the method may also include, after coupling the fueling nozzle to the fueling fitting, discharging the water from the holding tank through a drain valve. Discharging the water from the holding tank through the drain valve may discharge the water into a floor drain. 
     In some embodiments, the vehicle comprises a lift truck including a tractor unit and a vertically movable platform mounted relative to the tractor unit. The platform is vertically movable between an upper position and a lower position. 
     In some embodiments, the vehicle comprises a lift truck including a tractor unit and a mast mounted relative to the tractor unit. The mast includes a fixed base and a vertically extendable mast section. A vertically movable platform is attached to the extendable mast section, the platform being vertically movable with the extendable mast section between an upper position and a lower position. 
     The foregoing and other objects and advantages will appear in the detailed description which follows. In the description, reference is made to the accompanying drawings which illustrate preferred embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a vehicle employing a fuel cell system; 
         FIG. 2  is a schematic view of one embodiment of a fuel cell system configured to automatically discharge the water generated by the fuel cell; 
         FIG. 3  is a plan view of a two port fitting adapted for use with the fuel cell system shown in  FIG. 2 ; 
         FIG. 4  is a plan view of an alternative two port fitting adapted for use with the fuel cell system shown in  FIG. 2 ; 
         FIG. 5  is a side view in partial section of a fueling nozzle sealingly coupled to the two port fitting of  FIG. 3 , and coupled to a fueling station via a fueling hose; 
         FIG. 6  is a schematic view of an alternative embodiment of a fuel cell system configured to automatically discharge the water generated by the fuel cell; and 
         FIG. 7  is a schematic view of an additional alternative embodiment of a fuel cell system configured to automatically discharge the water generated by the fuel cell. 
     
    
    
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed. 
     Referring now to the Figures, and more particularly to  FIG. 1 , the general arrangement of a representative vehicle, such as a lift truck  10 , incorporating a fuel cell system  12  is shown. For simplicity, the detailed description will describe the embodiments associated with the lift truck  10  incorporating the fuel cell system  12 . It is to be appreciated that the details of the invention may also be beneficial and adapted for a wide variety of devices and vehicles. Although the lift truck  10 , by way of example, is shown as a standing, fore-aft stance operator configuration lift truck, it will be apparent to those of skill in the art that the features of the invention are not limited to vehicles of this type, and can also be provided in various other types of vehicles, including but not limited to, other material handling and lift vehicle configurations. 
     As seen, one embodiment of the lift truck  10  includes a tractor unit  14  comprising an operator compartment  16  with an opening  18  for entry and exit of the operator. The compartment  16  includes a control handle  20  mounted to the tractor  14  near the front of the operator compartment  16 . A steering wheel  28  is also provided and is disposed above the turning wheel  30  it controls. The lift truck  10  includes two load wheels  32  proximate to a mast  22 . The mast  22  is mounted relative to the tractor unit  14 . The mast  22  includes a fixed base  23  and a vertically extendable mast section  25 , with a platform  27  attached to the extendable mast section  25 . The extendable mast section  25  raises and lowers the platform  27 . The platform  27  is shown including forks  24  and carrying a load  26 . 
     Referring to  FIGS. 1 and 2 , the lift truck  10  is shown to include a fuel cell system  12 . The fuel cell system  12  comprises a variety of components, including a fuel cell  42  in fluid communication with a fuel tank  44  and a water holding tank  46 . A fueling fitting  48  is shown on a side  50  of the tractor unit  14 . The fueling fitting  48  provides access for a fueling nozzle to refuel the fuel cell  12  in a similar fashion to refueling a gasoline powered vehicle. In certain embodiments, the fueling fitting  48  also provides access for discharging water from the holding tank  46 . Optionally, the holding tank  46  also includes a drain valve  56  for water discharge. 
     Fuel from the fuel tank  44  passes through a fuel line  40  and is available for the fuel cell  42 . As previously described, as the fuel cell  42  consumes the fuel and an oxidant, the output includes electrical power and water  52 . Thus, as fuel is consumed from the fuel tank  44 , the water from the fuel cell  42  is collected in the water holding tank  46 . The water  52  flows from the fuel cell  42  through a holding tank conduit  54  (or directly) into the holding tank  46  by way of gravity. It is to be appreciated that the water  52  may also be pumped or otherwise transferred to the holding tank during operation of the fuel cell  42 . 
     One or both of the water holding tank  46  and the fuel tank  44  may be sized accordingly so as the fuel is consumed from the fuel tank, there is sufficient space in the water holding tank  46  to hold the water generated. In a desirably sized system, as the last of the fuel is consumed, the water holding tank  46  is at or near capacity. 
     Referring now to  FIGS. 3 and 4 , alternative configurations of the fueling fitting  48  are shown. As seen in  FIG. 3 , the two-port fitting  60  includes a first port  62  for providing fuel to the fuel tank  44  through a fuel conduit  64 , and a juxtaposed second port  66  for removing water from the holding tank  46  through water conduit  68 . One or more seals  70 ,  72 ,  74  may be included, as would be known in the art, to provide a sealed fitting to a fueling nozzle  80 , to be described below.  FIG. 4  shows an alternative two-port fitting  60 ′ where the first port  62  and the second port  66  are configured, for example, to be one inside the other, i.e., as shown to be generally coaxial. 
     Referring now to  FIG. 5 , the fueling nozzle  80  is used to refuel the fuel cell  12 . The fueling nozzle  80  is shown coupled to a fueling pump or station  86  via hose  78 , and sealingly coupled to the two port fitting  60 . The fueling nozzle  80  includes a mating channel  82  for providing a fluid flow path for the fuel from a fuel storage tank  84  at the fueling station  86  to the first port  62  on the two port fitting  60 . When used with this two port fitting, the fueling nozzle  80  may also be fitted with a mating channel  88 , as shown, for providing a fluid flow path to discharge the water  52  from the water holding tank  46 . The water is discharged from the holding tank  46  through the water conduit  68  and second port  66 , through mating channel  88 , and to the water storage tank  90  at the fueling station  86 . The water storage tank  90  desirably has a greater capacity than the holding tank  46  on the lift truck  10 . 
     When the fueling nozzle  80  is properly connected to the two-port fitting  60  as shown, the fueling process may begin, and simultaneously, or before or after the fueling process, a water pumping system  92  draws, e.g., suctions, the accumulated water from the water holding tank  46  through the water conduit  68  and the fueling nozzle  80  to the water storage tank  90 . It is to be appreciated that the pumping system  92  may comprise a component of the fueling station  86 , as shown, or alternatively, the pumping system  92  may be incorporated into the fuel cell system  12  on the lift truck  10 . The pumping system may include any known pump configuration useful to pump fluids (e.g., a piston pump, a blower, a turbine, a fan, a linear pump, a rotary vane pump, a centrifugal pump, a reciprocating pump, a diaphragm pump or combinations thereof, as non-limiting examples), and may be manually operated or automatically operated (e.g., AC or DC electrically powered). 
     In this way, the water is automatically transferred from the holding tank  46  on-board the lift truck  10  to the water storage tank  90  at the fueling station  86  every time the fuel cell system  12  is fueled. Alternatively, the water may be transferred from the holding tank  46  to an appropriate drain  108 . The capacity of the water holding tank  46  may be sized as a direct function of the amount of fuel consumed, thus, related directly to the size of the fuel tank  44  storage capacity. Therefore, the fueling operation time can always be appropriate to the amount of time the pumping system  92  requires to drain the accumulated water  52 , whether for partial or complete re-fueling. 
     Referring to  FIG. 6 , an alternative embodiment of a fuel cell system  112  is shown. In the Figure, like components are given the same reference numerals as in  FIGS. 1-2 . For simplicity and brevity the description of these components is not repeated. 
     In this embodiment, a sensing system  100  is adapted to sense when the fueling nozzle  80  is either coupled to the fueling fitting  102  and/or when fueling is in process. A variety of sensing devices would be apparent to those of skill in the art, such as a switch, a fluid flow sensor, a mechanical link, a hydraulic link, and/or a pneumatic link, as non-limiting examples. In this embodiment, the fueling fitting  102  may comprise a single fuel port  104  for fuel transfer. When either are sensed, (i.e., when the fueling nozzle  80  is either coupled to the fueling fitting  102  and/or when fueling is in process), the sensing system  100  causes a drain valve  106 , (e.g., an open/close solenoid valve), on the water holding tank  46  to open and allow the water  52  to drain. In one embodiment, the sensing system  100  may be positioned on or near the fueling fitting  102  so as to detect when the fueling nozzle  80  is coupled to the fueling fitting  102 . In another embodiment, or in combination, the sensing system  100  may be positioned to detect the flow of fuel through the fueling fitting and/or through the fuel conduit  64 , and/or to detect the pressure of the incoming fuel. 
     The fueling station  86  location may be equipped with one or more suitable floor drains  108  to collect the water, and/or the water  52  may be allowed to drain to a building drain system  110 , for example. When fueling is completed or stopped, and/or when the fueling nozzle  80  is removed from the fueling fitting  102 , the sensing system  100  would sense either condition and cause the drain valve  106  on the water holding tank to close. 
     Similar to the fuel cell system  12  described above including a pumping system  92 , this fuel cell system  112  also provides an automatic drain process, and, similar to the pumping configuration, may be self-timing, providing drain time proportional to the amount of fuel supplied to the vehicle. 
       FIG. 7  shows an additional alternative embodiment of a fuel cell system  212 , which incorporates the ability to utilize either or both the pumping system  92  and the sensing system  100  as described above. When the lift truck  10  is being fueled and/or is coupled to a fueling nozzle  80 , the pumping system  92  may withdraw water from the holding tank  46  or, the sensing system  100  may drain the holding tank  46  through the drain valve  106 . Combining the pumping system  92  and the sensing system  100  as part of the fuel cell system  212  allows the user of the lift truck  10  additional flexibility to refuel the lift truck and discharge water at a fueling station that may or may not have available the two port fueling nozzle  80 , and may only have available a drain  108 . 
     Preferred embodiments have been described in considerable detail. Many modifications and variations to the preferred embodiment described will be apparent to a person of ordinary skill in the art. Therefore, the invention should not be limited to the embodiments described.