Cell unit for fuel cells

Details Cell unit for fuel cells Cell unit for fuel cells

1998-09-18

2001-01-30

Nuzzolillo, Maria (Department: 1745)

Chemistry: electrical current producing apparatus, product, and

With pressure equalizing means for liquid immersion operation

C429S006000, C429S006000, C429S006000

Reexamination Certificate

active

06180274

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the structure of cell units for use in fuel cells.
BACKGROUND OF THE INVENTION
As shown in
FIG. 7
, cell units for use in fuel cells generally comprise a cell
2
having an electrode portion
24
which is composed of an anode
21
formed on one surface of an electrolyte
20
in the form of a plate or film and a cathode
22
formed on the other surface of the electrolyte
20
, an anode side plate
3
having an anode side chamber
30
facing the anode for passing hydrogen gas or like fuel therethrough, and a cathode side plate
4
having cathode side chambers
40
facing the cathode for passing air or like oxidant therethrough. A multiplicity of cell units
10
of the structure described are arranged in layers for use in the fuel cell.
The fuel cell has fuel manifolds for supplying the fuel from outside uniformly to the anode side chambers
30
of the respective anode side plates
3
and discharging the fuel flowing through the anode side chambers
30
to the outside. The fuel manifolds are formed inside the cell units
10
, or alternatively externally of the cell units. Similarly, the fuel cell has oxidant manifolds for supplying the oxidant from outside uniformly to the cathode side chambers
40
of the respective cathode side plates
4
and discharging the oxidant flowing through the cathode side chambers
40
to the outside. The oxidant manifolds are formed inside the cell units
10
, or alternatively externally of the cell units.
FIG. 7
shows fuel manifolds formed inside the cell unit
10
. More specifically,
FIG. 7
shows fuel supply manifolds
31
,
90
extending through the anode side plate
3
and the cathode side plate
4
, respectively, and communicating with the anode side chamber
30
of the anode side plate
3
for supplying the fuel to the anode side chamber
30
, and fuel discharge manifolds
32
,
91
extending through the anode side plate
3
and the cathode side plate
4
, respectively, and communicating with the anode side chamber
30
of the anode side plate
3
for discharging the fuel passing through the anode side chamber
30
.
As shown in
FIG. 7
, a seal member
5
for preventing the fuel from leaking is disposed between the anode side plate
3
and the cathode side plate
4
.
Provision of seal members requires many steps of work for forming seal grooves and installing the seal members and is therefore costly, so that it is desired to minimize the number of locations where the seal member needs to be provided.
To diminish the number of seal members
5
to be installed for the fuel manifolds, the anode side plate
3
of one cell unit
10
and the cathode side plate
4
of another cell unit
10
adjacent thereto are integrally made into a bipolar plate
8
as shown in FIG.
8
. Since this structure requires no seal member
5
between the anode side plate
3
and the cathode side plate
4
of the adjacent cell units
10
, the number of seal members
5
needed for the fuel manifolds can be reduced.
However, in fabricating a fuel cell with use of bipolar plates
8
, it is necessary to arrange cells
2
and bipolar plates
8
alternately in layers. At this time, the cell
2
adheres to the bipolar plate
8
adjacent thereto. Accordingly, when there arises a need to replace the cell
2
, the cell
2
must be peeled off the bipolar plate
8
and is therefore difficult to repair or maintain. Moreover, the cell substituted for the removed cell is likely to alter the performance depending on the state of the cell as attached to the bipolar plate
8
, failing to assure the fuel cell of stabilized performance in its entirety.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a cell unit for use in fuel cells which is reduced in the number of seal members required for fuel manifolds or oxidant manifolds to simplify the fabrication process of the unit and to render the cell unit easy to maintain or repair.
To fulfill the above object, the present invention provides a cell unit for use in fuel cells which comprises an anode side plate having a pair of first and second stepped portions approximately parallel to each other and projecting from one surface of a generally rectangular base plate, the stepped portions and the base plate surface defining a recessed portion, the base plate surface of the recessed portion being recessed to provide an anode side chamber; a cell including an electrode portion having an anode formed on one surface of an electrolyte in the form of a plate or film and a cathode formed on the other surface of the electrolyte, the cell being accommodated in the recessed portion of the anode side plate with the anode facing the anode side chamber of the anode side plate; and a cathode side plate having a cathode side chamber formed in one surface of a generally rectangular base plate, the cathode side plate being accommodated in the recessed portion of the anode side plate with the cathode side chamber facing the cathode of the cell. The stepped portions of the anode side plate have respective top faces substantially flush with the other surface of the cathode side plate, with the cell and the cathode side plate accommodated in the recessed portion of the anode side plate.
Alternatively, the anode side plate can be formed with a stepped portion on one surface of its base plate along the entire outer periphery thereof.
A fuel supply manifold for passing a fuel therethrough and a fuel discharge manifold for passing therethrough the fuel to be discharged can be made to extend through the respective stepped portions and the base plate, with the supply manifold held in communication with the anode side chamber and with the anode side chamber held in communication with the discharge manifold by respective internal manifolds.
A stepped portion or stepped portions can be formed on the cathode side plate instead of the stepped portion or portions formed on the anode side plate.
A bipolar plate is usable in the cell unit of the invention for use in fuel cells, the bipolar plate comprising a generally rectangular base plate and being provided with a stepped portion on each of opposite surfaces of the base plate to form an anode side chamber in one of the surfaces and a cathode side chamber in the other surface.
The cell unit of the present invention can be smaller in the number of seal members required than in conventional cell units since the seal members conventionally used between the anode side plate and the cathode side plate can be dispensed with.
With the cell unit of the invention, the cell is sandwiched between the anode side plate and the cathode side plate, so that the components of fuel cells can be fabricated in the form of cell units. The fuel cell can therefore be checked for performance or maintained from unit to unit.
Since the fuel cell is fabricated by arranging a plurality of cell units of the invention into an assembly of layers, a malfunctioning cell unit, if found, can be removed singly after use for replacement. This results in facilitated repair or maintenance, assuring the fuel cell of more stabilized performance.
When comprising the bipolar plate of the invention, the cell unit also has these advantages.


REFERENCES:
patent: 4988583 (1991-01-01), Watkins et al.
patent: 5176966 (1993-01-01), Epp et al.
patent: 5300370 (1994-04-01), Washington et al.
patent: 5527363 (1996-06-01), Wilkinson et al.
patent: 5912088 (1999-06-01), Ernst

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