Chemistry: electrical current producing apparatus – product – and – With pressure equalizing means for liquid immersion operation
Reexamination Certificate
2001-08-24
2004-01-13
Ruthkosky, Mark (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
With pressure equalizing means for liquid immersion operation
C429S006000
Reexamination Certificate
active
06677071
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bipolar plate for a fuel cell, in particular, a corrugated bipolar plate made of metal. The bipolar plate provided by this invention can simplify the manufacturing process of the fuel cell and thus, reduce the production costs. Specially, the dimension and weight of the fuel cell can be decreased such that the actual utilization and mass production of the fuel cell become more convenient and practical.
2. Description of the Related Art
With the rapid growth of human civilization, the consumption of traditional energy sources, such as coal, oil and natural gas, increases rapidly. This has resulted in a serious pollution to the global environment, as well as various environmental problems such as global warming and acid rain. It is now recognized that the natural energy resources are limited. Therefore, if the present rate of consumption continues, all existing natural energy sources will be exhausted in the near future. Accordingly, many developed countries are dedicated to research and development of new and replaceable energy sources. The fuel cell is one of the most important and reasonably priced choices. Compared with traditional internal combustion engines, the fuel cell has many advantages such as high energy transformation efficiency, clean exhaust, low noise, and no consumption of traditional gasoline.
In brief, a fuel cell is an electrical power generation device powered by the electrochemical reaction of hydrogen and oxygen. In basic terms, the reaction is a reverse reaction of the electrolysis of water, to transfer the chemical energy into electrical energy. The basic construction of a fuel cell, for example, a proton exchange membrane fuel cell, comprises a plurality of cell units. The construction of the cell unit can be generally illustrated in FIG.
1
. It comprises a proton exchange membrane (PEM)
10
at the middle, with the two sides thereof provided with a layer of catalyst
12
, each of the two outsides of the catalyst
12
being further provided with a gas diffusion layer (GDL)
14
. An anode plate
16
and a cathode plate
18
are further provided at the outermost sides adjacent to the GDL
14
. After tightly combining all the above elements together, a cell unit is formed. For the practical application of a fuel cell, a plurality of the above cell units are stacked and serially connected to provide sufficient power, as illustrated in FIG.
2
. Therefore, two adjacent cell units can share a common polar plate
20
, as illustrated in
FIG. 3
, which serves as the anode and the cathode for the two adjacent cell units respectively. Accordingly, such a polar plate
20
is usually referred to as a bipolar plate.
Generally, as illustrated in
FIG. 3
, the two sides of the bipolar plate
20
are provided with many grooves
22
for transporting the gases for reaction, such as hydrogen and air (to provide oxygen), as well as moving the reactants, such as water droplet or vapor, out of the bipolar plate
20
. The conventional bipolar plate
20
is made of pure graphite or a graphite composite. Thus, the grooves on the graphite plate are usually formed by additional mechanical machining with complicated processes and at considerable cost. In addition, if the graphite plate is made by the compression molding of graphite powder, it must be further coated with resin or other material to seal the voids thereof. Moreover, graphite plate has a relatively low extensibility and thus cracks can be formed very easily. The crack on the bipolar plate may introduce leakage of gas and thereby impair the operation efficiency of the fuel cell. Furthermore, due to the requirement of adequate mechanical strength, the thickness of the graphite plate cannot be very thin, so the overall dimension occupied by the fuel cell cannot be further reduced.
BRIEF SUMMARY OF THE INVENTION
It is a primary objective of this invention to overcome the disadvantages of the conventional bipolar plate and to provide a bipolar plate that is thin, light, made by a simplified process, and has a low cost to manufacture. Accordingly, the space occupied by the fuel cell can be reduced and the manufacturing cost of the fuel cell can be lowered, so that the fuel cell is suitable for mass production and commercialization.
The major technical content of this invention is to make a corrugated bipolar plate from a metal sheet and form a plurality of parallel grooves which are complementary to each other on the two side surfaces of the bipolar plate. Because the bipolar plate of this invention is made of metal, the thickness thereof can be relatively thin and, the dimension and weight of the fuel cell can be significantly reduced. In addition, the manufacturing processes of the bipolar plate are simplified and the relative costs can be decreased.
The structures and characteristics of this invention can be realized by referring to the appended drawings and explanations of the preferred embodiments.
REFERENCES:
patent: 4604332 (1986-08-01), Warszawski
patent: 5227256 (1993-07-01), Marianowski
patent: 5514487 (1996-05-01), Washington
patent: 6040076 (2000-03-01), Reeder
patent: 6322919 (2001-11-01), Yang
patent: 6503653 (2003-01-01), Rock
patent: 19910487 (2000-06-01), None
patent: 10019094 (2001-10-01), None
patent: 2359186 (2001-08-01), None
patent: 06-236765 (1994-08-01), None
patent: 10-308227 (1998-11-01), None
patent: WO 00215311 (2002-02-01), None
Asia Pacific Fuel Cell Technologies, Ltd.
Rosenberg , Klein & Lee
Ruthkosky Mark
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