Abstract:
A fuel cell powered vehicle is disclosed having a fuel storage tank, wherein the fuel tank is disposed on an undercarriage of the vehicle and has a substantially ovoid shape to militate against interference with a function of a suspension system of the vehicle.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a fuel cell powered vehicle an more particularly to a fuel cell powered vehicle having a fuel storage tank, wherein the fuel tank is disposed on an undercarriage of the vehicle and has a substantially ovoid shape. 
       BACKGROUND OF THE INVENTION 
       [0002]    Typical fuel cell powered vehicles use fuel cell power systems that convert a fuel and an oxidant into electricity. One type of fuel cell power system employs use of a proton exchange membrane (hereinafter “PEM”) to catalytically facilitate reaction of fuels (such as hydrogen) and oxidants (such as air or oxygen) into electricity. The fuel is typically stored in large pressurized fuel tanks and stored on an undercarriage of the vehicle. Due to the large fuel tank size, interior passenger space or cargo space may be reduced to provide enough fuel to meet vehicle performance requirements. Vehicle system efficiency concerns dictate that large fuel tanks, rather than a series of small tanks, be utilized for fuel storage. 
         [0003]    Typically, fuel tanks are cylindrical in shape, and are disposed transversely on the undercarriage of the vehicle, behind the rear passenger seats and between the wheel assemblies. Current fuel tanks are manufactured using a filament wound composite method. However, the use of the filament wound composite method restricts the shape of the fuel tank to a simple geometric shape, such as a cylindrical shape, for example. 
         [0004]    The large size and shape of the fuel tank often restricts the function of the vehicle suspension system and limits the suspension linkage shape and suspension configuration. In a vehicle utilizing a double A-arm type suspension system, the corners of a cylindrical fuel tank interfere with the suspension system. 
         [0005]    It would be desirable to develop a fuel storage tank for a fuel cell powered vehicle with an improved design adapted to maximize interior passenger space, cargo space, and fuel storage capacity, while minimizing interference a suspension system of the vehicle. 
       SUMMARY OF THE INVENTION 
       [0006]    Concordant and congruous with the present invention, a fuel tank for a fuel cell powered vehicle with an improved design adapted to maximize interior passenger space, cargo space, and fuel storage capacity, while minimizing interference with the suspension system of the vehicle, has surprisingly been discovered. 
         [0007]    In one embodiment, the fuel tank comprises an outer wall forming a cavity for housing a compressed fuel; a first portion having a first volume; a second portion having a second volume substantially equal to the first volume; and a third portion disposed between said first portion and said second portion and having a volume greater than the volume of each of said first portion and said second portion, the fuel tank adapted to be disposed on an undercarriage of a fuel cell powered vehicle and minimize an interference with a suspension system of the vehicle. 
         [0008]    In another embodiment, the fuel tank comprises a substantially ovoid shaped outer wall, said outer wall forming a cavity for housing a compressed fuel, the fuel tank adapted to be disposed on a fuel cell powered vehicle and minimize an interference with a suspension system of the vehicle. 
         [0009]    In another embodiment, the fuel cell propulsion system comprises a fuel cell system, including a stack which includes a plurality of fuel cell plates; and a fuel tank having an outer wall forming a cavity for housing a compressed fuel, the outer wall having a first portion having a first volume, a second portion having a second volume substantially equal to the first volume, and a third portion disposed between said first portion and said second portion and having a volume greater than the volume of each of said first portion and said second portion, the fuel tank adapted to be disposed on an undercarriage of a fuel cell powered vehicle and minimize an interference with a suspension system of the vehicle. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0010]    The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which: 
           [0011]      FIG. 1  is a schematic rear view of a vehicle incorporating a suspension system and a fuel tank as known in the art; 
           [0012]      FIG. 2  is a schematic rear view of a vehicle and a first suspension system incorporating a fuel tank according to an embodiment of the invention; 
           [0013]      FIG. 3 , is a perspective view of the fuel tank of  FIG. 2  having a substantially rectangular cross-sectional shape; 
           [0014]      FIG. 4  is a schematic rear view of a vehicle and a second suspension system incorporating the fuel tank illustrated in  FIG. 2 ; and 
           [0015]      FIG. 5  is a schematic rear view of a vehicle and suspension system incorporating a fuel tank according to another embodiment of the invention. 
           [0016]      FIG. 6  is a perspective view of the fuel tank of  FIG. 5  having a substantially circular cross-sectional shape. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0017]    The following detailed description and appended drawings describe and illustrate various exemplary embodiments of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. 
         [0018]      FIG. 1  illustrates a vehicle  24 ′ with a fuel tank  10 ′ according to the prior art. The fuel tank  10 ′ has a substantially cylindrical shape. As shown, the cylindrical shape of the fuel tank  10 ′ intersects the fuel tank  10 ′ and interferes with a suspension system  26 ′ of the vehicle  24 ′. The shape of the fuel tank  10 ′ also limits a movement of components of the suspension system  26 ′ such as a linkage (not shown), for example. A configuration of the suspension system  26 ′ is also restricted. 
         [0019]      FIG. 2  shows a fuel tank  10  according to an embodiment of the invention. The fuel tank  10  includes an outer wall  12 , a first portion  14 , a second portion  16 , and a third portion  18 . Typically, the fuel tank  10  depends from an undercarriage (not shown) of a fuel cell powered vehicle  24 . It is understood that the fuel tank  10  may be disposed on any vehicle and on any portion of the vehicle, as desired. 
         [0020]    The outer wall  12  has a length  20  and a width  22  and forms a cavity adapted to house a fuel (not shown). In the embodiment shown, the length  20  of the outer wall  12  of the fuel tank  10  is greater than the width  22 , and the first portion  14  and the second portion  16  have a substantially rounded first end  15  and second end  17 , respectively. Therefore, the outer wall  12  has a substantially ovoid or football shape. It is understood that the outer wall  12  may have any shape with the length  20  greater than the width  22 , as desired. As shown in  FIG. 3 , the outer wall  12  has a substantially flat top  12   a , a substantially flat bottom  12   b , and substantially flat sides  12   c  to form a substantially rectangular cross-sectional shape. It is understood that the top  12   a , bottom  12   b , and sides  12   c  may have any configuration to form a substantially circular cross-sectional shape, a substantially triangular cross-sectional shape, a substantially ovoid cross-sectional shape, and other cross-sectional shape, as desired. It is further understood that the outer wall  12  may be formed from any conventional material with mechanical properties sufficient to house a compressed fuel. The outer wall  12  may be formed from a metal, a plastic, a composite material, and any other conventional material capable of withstanding high fluid pressures, as desired. The fuel may be a liquid or a compressed gas, such as hydrogen, for example. 
         [0021]    The first portion  14  of the fuel tank  10  is formed adjacent the first end  15  of the fuel tank  10  and is disposed adjacent the wheel assembly  28  of the vehicle  24 . A suspension system  26  of the vehicle  24  is disposed around the first portion  14  of the fuel tank  10 . As shown in  FIG. 2 , the suspension system  26  is a double-A arm suspension system. It is understood that the first portion  14  may have any volume, as desired. It is further understood that the suspension system  26  may be any conventional suspension system  26  such as double A-arm shown in  FIG. 4 , multi-link, and leaf and beam, for example. 
         [0022]    The second portion  16  of the fuel tank  10  is formed adjacent the second end  17  of the fuel tank  10  and is disposed adjacent the wheel assembly  30  of the vehicle  24 . The suspension system  26  of the vehicle  24  is disposed around the second portion  16  of the fuel tank  10 . The volume of the second portion  16  is substantially equal to the volume of the first portion  14 . It is understood that the second portion  16  may have any volume, as desired. 
         [0023]    The third portion  18  of the fuel tank  10  is formed intermediate the first portion  14  and the second portion  16  of the fuel tank  10 . The volume of the third portion  18  is greater than the volume of each of the first portion  14  and the second portion  16 . 
         [0024]    In use, the fuel tank  10  is in fluid communication with a fuel cell system (not shown). When the vehicle  24  is in operation, the fuel tank  10  provides a feed of a fuel such as hydrogen to the anode side of the fuel cell assembly. Concurrently, a stream of an oxidant such as oxygen is fed into the cathode side of the fuel cell system. On the anode side, the hydrogen in the hydrogen stream is catalytically split into protons and electrons. In a polymer electrolyte membrane fuel cell, the protons permeate through the membrane to the cathode side. The electrons travel along an external load circuit to the cathode side creating the current of electricity in the fuel cell assembly. On the cathode side, the oxygen in the oxidant stream reacts with the protons permeating through the membrane and the electrons from the external circuit to form water molecules. 
         [0025]    Interference with the performance of the suspension system  26  by the fuel tank  10  during use of the vehicle  24  is minimized due to the substantially ovoid shape of the fuel tank  10 . The substantially ovoid shape of the fuel tank  10  minimizes the interference with the suspension system  26  by positioning the first portion  14  and the second portion  16  within the confines of the suspension system  26 , without crossing or contacting the suspension system  26 . To compensate for the volume of the fuel tank  10  lost due to the shape of the first portion  14  and the second portion  16 , the width  22  of the fuel tank  10  is maximized in the third portion  18 , yielding a third portion  18  with a volume greater than the volumes of each of the first portion  14  and the second portion  16 . By maximizing the volume of the third portion  18 , the storage volume of the fuel tank  10  is maximized to provide a sufficient amount of fuel to the vehicle  24  to meet driving range requirements. A further advantage of providing a fuel tank  10  which minimizes interference with the suspension system  26  is that the interior and cargo space of the vehicle  24  required to be removed to provide for the suspension system  26  and fuel tank  10  is minimized, thereby maximizing optimum vehicle  24  utility and comfort. 
         [0026]      FIG. 5  shows a fuel tank  10 ″ according to a second embodiment of the invention. The fuel tank  10 ″ is similar to the fuel tank  10  shown in  FIG. 2  except that the outer wall  12 ″ of the fuel tank  10 ″ at the first end  15 ″ and the second end  17 ″ has a frustoconical portion  32 ″ on the first portion  14 ″ and a frustoconical portion  34 ″ on the second portion  16 ″. As shown in  FIG. 6 , the outer wall  12 ″ has a substantially rounded top  12   a ″ and a substantially rounded bottom  12   b ″ to form a substantially circular cross-sectional shape. It is understood that the top  12   a ″ and the bottom  12   b ″ may have any configuration to form a substantially circular cross-sectional shape, a substantially triangular cross-sectional shape, a substantially ovoid cross-sectional shape, and other cross-sectional shape, as desired. The remaining structure, use, and advantages are substantially the same as described above for  FIGS. 2 ,  3 , and  4 . 
         [0027]    From the foregoing description, one ordinarily skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications to the invention to adapt it to various usages and conditions.