Fuel cell assembly system

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.

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.

DETAILED DESCRIPTION

Referring toFIGS. 1 and 2, a fuel cell assembly10includes a manifold12, 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 manifold12are a plurality of fuel cell stacks14,16,18and20. Each stack includes a plurality of standard commercially available fuel cells19coupled 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 manifold12. For example, stacks14and16may have a 1 kilowatt capacity, stack18may have a 5 kilowatt capacity and stack20may have a 10 kilowatt capacity. As best seen inFIG. 1, the manifold12includes individual passages formed therein for the communication of hydrogen fuel, air and coolant into and out of the fuel cell stacks, including hydrogen inlets22and28, coolant inlets24and30, and air outlets26and32.

As best seen inFIG. 2, fuel cell stack20includes a positive electrical terminal34, a negative electrical terminal36, a hydrogen inlet38, a coolant inlet40, an air outlet42, an air inlet44, a coolant outlet46and a hydrogen outlet48. Fuel cell stacks14,16and18have similar components similarly arranged, but stacks with different capacities will have different spacings among their terminals, inlets and outlets.

As best seen inFIG. 3, the manifold12has a plurality of zones14′,16′,18′ and20′, each corresponding to one of the fuel cell stacks14,16,18and20. The zones14′,16′,18′ and20′ preferably have differing characteristics corresponding to the differing characteristics of the fuel cell stacks14,16,18and20. For example, zones14′ and16′ may have a smaller area or “footprint” corresponding to a small capacity fuel cell stack, zone18′ may have an intermediate area or “footprint” corresponding to an intermediate capacity fuel cell stack and zone20′ 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 zone20′ includes a positive electrical terminal34′ a negative electrical terminal36′, a hydrogen outlet38′, a coolant outlet40′, an air inlet42′, an air outlet44′, a coolant inlet46′ and a hydrogen inlet48′.

FIG. 4is a sectional view which shows the right-hand (viewingFIG. 2) set of connections between the fuel cell stack20and the manifold12. Negative terminal36is connected to a negative conductor50in the manifold12. Air inlet port44is connected to an air supply passage52in the manifold12. Coolant outlet port46is connected to a coolant passage54in the manifold12. Hydrogen outlet port48is connected to a hydrogen passage56in the manifold12.

Referring now toFIG. 5, a fuel cell stack14,16,18or20is clamped to the manifold12by a pair of spring toggle clamps60on opposite sides of the stack. Each clamp60releasably engages a tab62formed on the side of the stack.

Referring now toFIG. 6, a block-off plate64may be clamped to the manifold12in place of one or more of the fuel cell stacks14,16,18or20. Each block-off plate64includes a pair of tabs66which engage a pair of the spring toggle clamps60.

FIG. 7illustrates a representative connection between the manifold12and a fuel cell stack16–20or a block-off plate64. A bore70extends into the manifold12and forms an annular shoulder72between bore70and a smaller diameter passage74. A bore76extends into the fuel cell stack16–20and forms an annular shoulder78between bore76and a smaller diameter passage80. The bore76will be a blind bore and there will be no passage80in the case of block-off plate64. An O-ring seal82is mounted in an annular groove84formed in the wall of bore76. A cylindrical tube86has one end sealingly received by bore70, such as a press fit, and engaging shoulder72. The other end of tube86is releasably received by bore76and is sealingly engaged by O-ring82. Such a connection would be used for each of the ports38–48.

FIGS. 8–10illustrates an alternate connection between the manifold12and a fuel cell stack16–20. This alternate connection self-seals the various manifold ports and eliminates the need for the block-off plate. Referring toFIG. 8, a bore90extends into the manifold12and forms an annular shoulder92between bore90and a smaller diameter passage94. The outer portion96of bore90forms screw threads. A check valve seat member98is screwed into the threaded portion96and forms a check valve seat100. A spring102is mounted in the bore90and urges a check valve ball104into engagement with seat100.

A threaded bore110extends into the fuel cell stack16–20and receives a valve plunger112. Referring toFIGS. 8 and 9, the plunger112has a hollow threaded base114, a hollow cylindrical sleeve115, a central stern116and a ball engager118on the outer end of the stern116. The stem comprises four axially and radially extending web members117. The base114, sleeve115and stem116form passages120which communicate the end of the stem116with passage80in the stack16–20. O-ring seals122and124are mounted in grooves on the sleeve115and engager118, respectively. When the fuel cell stack16–20is spaced apart from the manifold12, the ball104is held against seat100and the corresponding manifold passage is sealed from the exterior environment. As best seen inFIG. 9, flat surfaces126,128are formed on the periphery of sleeve115so that plunger112may be manipulated with a wrench (not shown).

Referring now toFIG. 10, when one of the fuel cell stacks16–20is placed against the manifold12, the ball engager118moves the ball104away from seat100and the manifold passage is communicated with the corresponding cell stack passage via passages120.

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.