Chemistry: electrical current producing apparatus – product – and – Having diverse cells or diverse removable cells in a support...
Reexamination Certificate
1998-11-06
2001-02-27
Kalafut, Stephen (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Having diverse cells or diverse removable cells in a support...
C429S006000, C429S006000
Reexamination Certificate
active
06194092
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a portable power system using fuel cells, and more particularly to a fuel cell apparatus employing polymer electrolyte fuel cells using the air as an oxidizer.
2. Related Art
Examples of prior art techniques, using a fuel cell as a portable power source, are disclosed in JP-A-04-308662 and JP-A-06-60894, and these publications disclose a construction in which a phosphoric acid fuel cell is operated by hydrogen, supplied from a hydrogen storage alloy, and the air. JP-A-54-22537 and JP-A-02-260371 disclose a construction in which a polymer electrolyte fuel cell is operated by hydrogen, supplied from a hydrogen storage alloy, and the air.
In a polymer electrolyte fuel cell, a proton exchange membrane (PEM), which is a polymer electrolyte, is used as an electrolyte, and its general construction is shown in FIG.
3
. In the construction using this proton exchange membrane
17
, a layer of a positive electrode (oxygen electrode)
18
and a layer of a negative electrode (hydrogen electrode)
19
are formed respectively on opposite sides of the proton exchange membrane
17
, and these jointly constitute a unit cell
20
.
In the case where hydrogen is used as a fuel while oxygen is used as an oxidizer, a reaction, expressed by the following formula (1), occurs at the negative electrode at the interface of contact between a catalyst and the polymer electrolyte while a reaction, expressed by the following formula (2), occurs at the positive electrode, so that water is formed.
H
2
2H
+
+2e
−
(1)
½O
2
+2H
+
+2e
−
→H
2
O (2)
The catalyst serves to provide an active site or spot of the reaction, and the active sites serve as a conductor for the electrons in the above reactions, and the polymer electrolyte serves as a conductor for the hydrogen ions. However, the polymer electrolyte does not exhibit ion-permeability before it becomes moistened, and therefore with respect to a feature of the power system employing the polymer electrolyte fuel cell, a method of moistening the polymer electrolyte has been extensively studied. The unit cells
20
are connected in series by using separator plates
21
and gaskets
22
(see
FIG. 4
) to form a laminate
23
(see
FIG. 5
) which is fastened by end plates
24
to thereby provide one electricity-generating unit.
During the generation of electricity, the energy of an excess voltage, corresponding to a current density at which the electricity is generated, is discharged from the fuel cell body of this construction, and therefore the fuel cell body serves as a heat-generating source.
The hydrogen storage alloy of the hydrogen storage tank for supplying hydrogen to the fuel cell performs a representative reaction, expressed by the following formula (3), in accordance with the storage and discharge of hydrogen:
M: hydrogen storage alloy, H: hydrogen &agr;, &bgr;: ratio of hydrogen atoms H to hydrogen storage alloy atoms M in a solid phase (This ratio corresponds to a stoichiometric composition of a hydride phase)
The hydrogen content of the metal, exhibiting a phase (which is a metal phase in which hydrogen is dissolved), increases, and at the time of the reaction (the reaction in a right-hand direction in formula (3)) when the &agr; phase reacts with hydrogen gas and is converted into &bgr; phase (hydride), which is a hydride phase, heat &Dgr;H of formation is produced. When hydrogen is emitted from the metal hydride, the &bgr; phase is converted into the &agr; phase, thereby absorbing the heat &Dgr;H, and this characteristic is already known. At this time, in order to stably. supply hydrogen, it is necessary to supply heat to the hydrogen storage alloy, and therefore there have been proposed various methods of supplying heat to the hydrogen storage tank.
However, in the above conventional portable fuel cell and the above conventional polymer electrolyte fuel cell system, any consideration has not been given to a construction for achieving a compact design in view of the heat transmission between the fuel cell body, serving as the heat-generating source, and the hydrogen storage alloy portion serving as the heat-absorbing source.
For example, in the construction disclosed in JP-A-54-22537 and JP-A-02-260371, the polymer electrolyte fuel cell is operated by hydrogen supplied from the hydrogen storage alloy, but these publications show only the construction for transmitting heat of the fuel cell to the hydrogen storage alloy, the construction of a wick member for recovering the formed water, and the construction of a water-permeable member, and do not disclose any construction for achieving the compact design. U. S. Pat. No. 5,200,278 discloses various techniques related to the construction of a polymer electrolyte fuel cell and such a fuel cell system, but does not suggest any construction for achieving a compact design, and there is a problem that any consideration has not been given to a construction for achieving the compact design in view of the heat transmission between the fuel cell body, serving as the heat-generating source, and the heat of the hydrogen storage alloy portion serving as the heat-absorbing source.
SUMMARY OF THE INVENTION
With the above problems of the prior art in view, it is an object of this invention to provide a portable power apparatus employing fuel cells, which enables a compact design of the apparatus.
According to the present invention, there is provided a fuel cell apparatus comprising a plurality of fuel cell bodies for generating electricity by the use of hydrogen and the air; a hydrogen storage tank for storing hydrogen required for the fuel cell bodies; a controller for controlling a flow of the hydrogen from the hydrogen storage tank and for controlling an operation and output of fuel cells in the fuel cell bodies; hydrogen supply means connecting the hydrogen storage tank to the fuel cell bodies so as to supply the hydrogen from the hydrogen storage tank to the fuel cell bodies and being releasably connected to the hydrogen storage tank; air feed means for supplying the air, in order to supply oxygen necessary for the generation of electricity by the fuel cells, to the fuel cell bodies; a secondary battery for driving the controller and for supplementally driving the air feed means; and casing receiving the above components therein; wherein the casing has air intake ports and an air discharge port for the air feed means, and also has means by which the hydrogen storage tank can be introduced into and removed from the casing; and wherein at least one pair of fuel cell bodies are disposed respectively on inner surfaces of opposite side walls of the casing, and the air (as cathode fuel) is introduced by the air feed means through the associated side wall of the casing, and is supplied to the fuel cell body. The hydrogen storage tank for supplying anode fuel to the fuel cell bodies is disposed on the side surface of each of the fuel cell body, facing away from a cathode fuel-supplying inlet thereof, through heat transmission means.
With this construction, the air (cathode fuel), introduced through the air intake ports, formed respectively on the opposite side walls of the casing, is supplied to the fuel cell bodies disposed respectively on the inner surfaces of the opposite side walls of the casing, and after oxygen in the air is consumed, the air absorbs heat from the fuel cell bodies serving as heat-generating members, and this heat can be supplied to the hydrogen storage tank disposed on those sides of the fuel cell bodies respectively facing away from the casing through the heat transmission means. The plurality of fuel cell bodies are provided, and the hydrogen storage tank is disposed between these fuel cell bodies, and by doing so, the heat transfer area of the hydrogen storage tank can be efficiently used for heat transmission purposes. With this system construction, the energy of the heat, generated from the fuel cell bodies, can be efficiently transmitted to
Ohara Hideo
Sugawara Yasushi
Uchida Makoto
Kalafut Stephen
Matsushita Electric - Industrial Co., Ltd.
Stevens Davis Miller & Mosher L.L.P.
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