Abstract:
A fuel cell assembly includes a manifold having a plurality of fuel cell connecting zones. At least some of the zones have differing characteristics such as area and arrangement of electrical connections and inlet and outlet ports corresponding to differing electrical power capacities. The assembly also includes one or more fuel cell stacks. At least some of the stacks have differing electrical power capacities, differing characteristics corresponding to the differing characteristics of the manifold zone, and corresponding differing arrangements of electrical connections and inlet and outlet ports. These differing characteristics are designed so that a fuel cell stack of a particular capacity can be connected only to a manifold zone corresponding to such capacity.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a fuel cell assembly system. 
   It is likely that fuel cells will be used in future vehicles. For example, fuel cells could be used as an auxiliary power source which could supply power for lights, electronics, electric drives and electrically powered implements attached to such a vehicle. The amount of fuel cell generated power needed will vary as a function of customer selected options and usage. Therefore, there will be a need for fuel cell assemblies of varying capacity. 
   SUMMARY 
   Accordingly, an object of this invention is to provide a fuel cell assembly whose capacity can be easily adapted to differing power needs. 
   This and other objects are achieved by the present invention, wherein a fuel cell assembly includes a manifold having a plurality of fuel cell connecting zones. At least some of the zones have differing characteristics such as area and arrangement of fuel cell connecting components and inlet and outlet ports corresponding to differing electrical power capacities. The assembly also includes a plurality of fuel cell stacks. At least some of the stacks have differing electrical power capacities, differing characteristics corresponding to the differing characteristics of the manifold zone, and corresponding differing arrangements of inlet and outlet ports. These differing characteristics are designed so that a fuel cell stack of a particular capacity can be connected only to a manifold zone corresponding to such capacity. A block-off plate is provided for coupling to a manifold zone where it is desired not to place a fuel cell stack. A connector arrangement is provided which seals the manifold connections when no block-off plate or fuel cell stack is coupled to a particular manifold zone and which eliminates the need for the block-off plate. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  is a side elevation view of a fuel cell assembly according to the present invention. 
       FIG. 2  is view along lines  2 — 2  of  FIG. 1 . 
       FIG. 3  is view along lines  3 — 3  of  FIG. 1 . 
       FIG. 4  is view along lines  4 — 4  of  FIG. 2 . 
       FIG. 5  is a perspective view of a fuel cell module mounted to a manifold of the present invention. 
       FIG. 6  is a perspective view of a block-off plate mounted to a manifold of the present invention. 
       FIG. 7  is a detailed sectional view of a connection between a fuel cell module and the manifold of the present invention. 
       FIG. 8  is a detailed sectional view of an alternate embodiment of a connection between a fuel cell module and the manifold of the present invention in a disconnected state. 
       FIG. 9  is a perspective view of a plug part of the connection of  FIG. 8 . 
       FIG. 10  is detailed sectional view of the connection of  FIG. 8  in a connected state. 
   

   DETAILED DESCRIPTION 
   Referring to  FIGS. 1 and 2 , a fuel cell assembly  10  includes a manifold  12 , which may be made of a solid piece of metallic material, such as aluminum, although a plastic or polymer material could satisfy the mechanical requirements of the material. Coupled to the side of the manifold  12  are a plurality of fuel cell stacks  14 ,  16 ,  18  and  20 . Each stack includes a plurality of standard commercially available fuel cells  19  coupled together in a conventional manner to form a fuel cell stack. Each stack preferably has a different power capacity and a different characteristic, such as an area or “footprint” on its side facing the manifold  12 . For example, stacks  14  and  16  may have a 1 kilowatt capacity, stack  18  may have a 5 kilowatt capacity and stack  20  may have a 10 kilowatt capacity. As best seen in  FIG. 1 , the manifold  12  includes individual passages formed therein for the communication of hydrogen fuel, air and coolant into and out of the fuel cell stacks, including hydrogen inlets  22  and  28 , coolant inlets  24  and  30 , and air outlets  26  and  32 . 
   As best seen in  FIG. 2 , fuel cell stack  20  includes a positive electrical terminal  34 , a negative electrical terminal  36 , a hydrogen inlet  38 , a coolant inlet  40 , an air outlet  42 , an air inlet  44 , a coolant outlet  46  and a hydrogen outlet  48 . Fuel cell stacks  14 ,  16  and  18  have similar components similarly arranged, but stacks with different capacities will have different spacings among their terminals, inlets and outlets. 
   As best seen in  FIG. 3 , the manifold  12  has a plurality of zones  14 ′,  16 ′,  18 ′ and  20 ′, each corresponding to one of the fuel cell stacks  14 ,  16 ,  18  and  20 . The zones  14 ′,  16 ′,  18 ′ and  20 ′ preferably have differing characteristics corresponding to the differing characteristics of the fuel cell stacks  14 ,  16 ,  18  and  20 . For example, zones  14 ′ and  16 ′ may have a smaller area or “footprint” corresponding to a small capacity fuel cell stack, zone  18 ′ may have an intermediate area or “footprint” corresponding to an intermediate capacity fuel cell stack and zone  20 ′ may have a larger area or “footprint” corresponding to a larger capacity fuel cell stack. In each zone the separation of the electrical connections and inlet and outlet ports is larger or smaller, in proportion to the dimensions of the corresponding zone. Manifold zone  20 ′ includes a positive electrical terminal  34 ′ a negative electrical terminal  36 ′, a hydrogen outlet  38 ′, a coolant outlet  40 ′, an air inlet  42 ′, an air outlet  44 ′, a coolant inlet  46 ′ and a hydrogen inlet  48 ′. 
     FIG. 4  is a sectional view which shows the right-hand (viewing  FIG. 2 ) set of connections between the fuel cell stack  20  and the manifold  12 . Negative terminal  36  is connected to a negative conductor  50  in the manifold  12 . Air inlet port  44  is connected to an air supply passage  52  in the manifold  12 . Coolant outlet port  46  is connected to a coolant passage  54  in the manifold  12 . Hydrogen outlet port  48  is connected to a hydrogen passage  56  in the manifold  12 . 
   Referring now to  FIG. 5 , a fuel cell stack  14 ,  16 ,  18  or  20  is clamped to the manifold  12  by a pair of spring toggle clamps  60  on opposite sides of the stack. Each clamp  60  releasably engages a tab  62  formed on the side of the stack. 
   Referring now to  FIG. 6 , a block-off plate  64  may be clamped to the manifold  12  in place of one or more of the fuel cell stacks  14 ,  16 ,  18  or  20 . Each block-off plate  64  includes a pair of tabs  66  which engage a pair of the spring toggle clamps  60 . 
     FIG. 7  illustrates a representative connection between the manifold  12  and a fuel cell stack  16 – 20  or a block-off plate  64 . A bore  70  extends into the manifold  12  and forms an annular shoulder  72  between bore  70  and a smaller diameter passage  74 . A bore  76  extends into the fuel cell stack  16 – 20  and forms an annular shoulder  78  between bore  76  and a smaller diameter passage  80 . The bore  76  will be a blind bore and there will be no passage  80  in the case of block-off plate  64 . An O-ring seal  82  is mounted in an annular groove  84  formed in the wall of bore  76 . A cylindrical tube  86  has one end sealingly received by bore  70 , such as a press fit, and engaging shoulder  72 . The other end of tube  86  is releasably received by bore  76  and is sealingly engaged by O-ring  82 . Such a connection would be used for each of the ports  38 – 48 . 
     FIGS. 8–10  illustrates an alternate connection between the manifold  12  and a fuel cell stack  16 – 20 . This alternate connection self-seals the various manifold ports and eliminates the need for the block-off plate. Referring to  FIG. 8 , a bore  90  extends into the manifold  12  and forms an annular shoulder  92  between bore  90  and a smaller diameter passage  94 . The outer portion  96  of bore  90  forms screw threads. A check valve seat member  98  is screwed into the threaded portion  96  and forms a check valve seat  100 . A spring  102  is mounted in the bore  90  and urges a check valve ball  104  into engagement with seat  100 . 
   A threaded bore  110  extends into the fuel cell stack  16 – 20  and receives a valve plunger  112 . Referring to  FIGS. 8 and 9 , the plunger  112  has a hollow threaded base  114 , a hollow cylindrical sleeve  115 , a central stern  116  and a ball engager  118  on the outer end of the stern  116 . The stem comprises four axially and radially extending web members  117 . The base  114 , sleeve  115  and stem  116  form passages  120  which communicate the end of the stem  116  with passage  80  in the stack  16 – 20 . O-ring seals  122  and  124  are mounted in grooves on the sleeve  115  and engager  118 , respectively. When the fuel cell stack  16 – 20  is spaced apart from the manifold  12 , the ball  104  is held against seat  100  and the corresponding manifold passage is sealed from the exterior environment. As best seen in  FIG. 9 , flat surfaces  126 ,  128  are formed on the periphery of sleeve  115  so that plunger  112  may be manipulated with a wrench (not shown). 
   Referring now to  FIG. 10 , when one of the fuel cell stacks  16 – 20  is placed against the manifold  12 , the ball engager  118  moves the ball  104  away from seat  100  and the manifold passage is communicated with the corresponding cell stack passage via passages  120 . 
   If no fuel cell stack is to be mounted to a particular manifold zone, then a simple threaded plug (not shown) may be screwed into the ports in that zone to seal them from the environment. 
   While the present invention has been described in conjunction with a specific embodiment, it is understood that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. For example, instead of different zones and stacks having different areas, they could have similar areas, but have different spacings or arrangements of components. Accordingly, this invention is intended to embrace all such alternatives, modifications and variations which fall within the spirit and scope of the appended claims.