U.S. patent application number 11/036984 was filed with the patent office on 2010-01-07 for micro fuel cell with membrane storage.
Invention is credited to David J. Pristash.
Application Number | 20100000434 11/036984 |
Document ID | / |
Family ID | 34994144 |
Filed Date | 2010-01-07 |
United States Patent
Application |
20100000434 |
Kind Code |
A1 |
Pristash; David J. |
January 7, 2010 |
Micro fuel cell with membrane storage
Abstract
An apparatus for the generation of electricity that may be in a
"standby" mode for long periods of time, i.e. many years. Thus, in
one embodiment of the invention, a fuel cell may include at least
one of the following features or components: a membrane, and/or
storage tanks or cells for hydrogen and oxygen, and/or an
"inertial" switch, which may optionally be assembled in close
proximity to a membrane. The inertial switch, when activated, may
rupture the membrane and allow the hydrogen and oxygen to mix in a
fuel cell.
Inventors: |
Pristash; David J.;
(Brecksville, OH) |
Correspondence
Address: |
SCHIFF HARDIN, LLP;PATENT DEPARTMENT
233 S. Wacker Drive-Suite 6600
CHICAGO
IL
60606-6473
US
|
Family ID: |
34994144 |
Appl. No.: |
11/036984 |
Filed: |
January 19, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60538211 |
Jan 23, 2004 |
|
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Current U.S.
Class: |
102/200 |
Current CPC
Class: |
F42C 15/26 20130101;
F42C 15/38 20130101; H01M 8/241 20130101; H01M 2250/00 20130101;
H01M 8/04201 20130101; H01M 8/04223 20130101; F42C 11/008 20130101;
Y02E 60/50 20130101; Y02T 90/40 20130101; H01M 8/1097 20130101;
H01M 8/04302 20160201; H01M 8/2457 20160201; H01M 2250/20 20130101;
H01M 8/04208 20130101; F42C 15/24 20130101; H01M 2008/1095
20130101 |
Class at
Publication: |
102/200 |
International
Class: |
F23Q 13/00 20060101
F23Q013/00; F42D 1/04 20060101 F42D001/04 |
Claims
1-22. (canceled)
23. A method for powering munitions, comprising the steps of:
containing a first fuel gas in a first storage tank; containing a
second fuel gas in a second storage tank; inhibiting at least one
of said first and second fuel gasses from reaching a fuel cell
membrane of a fuel cell while said fuel cell is in a dormant state;
installing said fuel cell in the dormant state in munitions; and
activating said fuel cell to power said munitions.
24. A method as claimed in claim 23, wherein said step of
activating includes activating said fuel cell by inertia.
25. A method as claimed in claim 23, further comprising the step
of: storing fuel for said fuel cell separate from a fuel cell
membrane when in the dormant state, and supplying the fuel to the
fuel cell membrane upon activation of said fuel cell.
26. A method as claimed in claim 23, wherein said first fuel gas is
oxygen and said second fuel gas is hydrogen.
27. A method as claimed in claim 23, wherein said step of
inhibiting includes blocking said first and second fuel gasses form
reaching said fuel cell membrane by first and second diaphragms,
and further comprising the step of: activating said fuel cell by
simultaneous puncture of said first and second membranes.
28. A method as claimed in claim 27, wherein said step of
activating by simultaneous puncture is by sliding movement of an
inertial body having first and second puncture needle, said sliding
movement causing said first and second puncture needles to puncture
respective ones of said first and second diaphragms.
29. A method as claimed in claim 28, wherein said first and second
puncture needles are hollow probes and said step of activating
includes initiating flow of said first and second fuel gasses
through respective ones of said first and second hollow probes.
30. A method as claimed in claim 23, wherein said step of
activating includes sliding an inertial body axially along a length
of a fuel cell structure.
31. A method as claimed in claim 30, further comprising the step
of: biasing said inertial body to an inactive position via a spring
force; overcoming said spring force by applying concussive force to
said inertial body.
32. A method as claimed in claim 23, wherein said steps of
containing said first and second fuel gases contains said first and
second fuel gases in tunneled storage tanks having internal
structures defining passageways in which the fuel gasses are
contained.
33. A method as claimed in claim 23, further comprising the step
of: resetting an activation mechanism from an active state to an
inactive state.
Description
CLAIM TO PRIORITY
[0001] This application claims priority under 35 U.S.C. 120 to
Provisional U.S. Patent Application 60/538,211, filed Jan. 23,
2004, the entire contents of which are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] This invention relates to the field of fuel cells, and more
particularly to the field of embedded electronics for systems that
are subject to a period of "standby" prior to powering up.
BACKGROUND OF THE INVENTION
[0003] In a fuel cell the chemical energy present in hydrogen and
the oxidant (oxygen) is cleanly, quietly and efficiently converted
electrochemically into electrical energy. The hydrogen is oxidized
at the anode (negative pole) and the oxygen (or air) is reduced at
the cathode (positive pole) of a single cell. The catalyst on the
anode promotes the oxidation of hydrogen molecules into hydrogen
ions (H.sup.+) and electrons: the hydrogen ions migrate through the
membrane to the cathode, where the cathode catalyst causes the
combination of the hydrogen ions, electrons and oxygen to produce
water. The polymer membrane in the so-called "Proton Exchange
Membrane Fuel Cell" (or PEMFC) conducts the hydrogen ions best when
fully hydrated.
[0004] The flow of electrons through an external circuit produces
electric current, which can be used, for example, by a direct
current (DC) electric motor. An inverter provides alternating
current (AC) for modem days applications.
[0005] The electrodes may be formed by a thin layer of catalyst
applied to an appropriate backing placed on the opposite surface of
the thin polymer membrane. Two bipolar plates are positioned
against this backing, one on each side of the membrane. The bipolar
plates have two functions: the transmission of electrons through
the elementary cells and the release of heat to the external
environment.
[0006] The side of bipolar plates facing the membrane electrode
assembly (MEA) may be provided with ribs, which allow for the
distribution of the gases (hydrogen and air) and the discharge of
the resultant product water.
[0007] The power requirement in fuel cell technology is achieved by
enlarging the cell area (to increase the ampere requirements) and
by combining a number of single cells in series to produce a fuel
cell stack by means of the bipolar plates (to increase voltage
requirements). A number of stacks are then combined to produce a
power plant as shown in FIG. 1.
[0008] In the conventional art shown in FIG. 1 an anode end plate 2
defines the left portion of a fuel cell stack 1. Hydrogen fuel is
channeled through the flow plates to the anode on one side of the
fuel cell, while oxygen is channeled to the cathode on the other
side of the cell. The catalyst on the anode end plate 2 causes the
hydrogen to split into positive hydrogen ions (protons) and
negatively charged electrons. The hydrogen ions migrate through a
membrane, which allows only the positively charged ions to pass
through it, to the cathode end plate 14, where the cathode end
plate 14 catalyst causes the combination of the hydrogen ions,
electrons and oxygen to produce water. The negatively charged
electrons travel along external circuit 16 to the cathode,
generating an electric current.
[0009] Next to anode end plate 2 is a membrane electric assembly 4,
and bipolar plate 6. Bipolar plate 6 is followed by membrane
electrode assembly 8, and then by bipolar plate 10. Finally, there
is another membrane electrode assembly 12 before cathode end plate
14. As shown in the figure, the bipolar plates 6 and 10 act as an
anode for one cell and a cathode for the adjacent cell. The plate
may be made of metal or a conductive polymer (which may be a
carbon-filled composite). The plate can incorporate flow channels
for the fluid feeds and may also contain conduits for heat
transfer. The membrane electrode assemblies are the structure
comprising of an electrolyte (proton-exchange membrane) with
surfaces coated with catalyst/carbon/binder layers and sandwiched
by two microporous conductive layers (which function as the gas
diffusion layers and current collectors).
[0010] The several types of fuel cells include the electrolyte
type. The electrolyte in between the electrodes defines the
operating temperature and, at that temperature, a suitable catalyst
may be selected.
[0011] A major standby power requirement exists with respect to
munitions production suitable for military application. Munitions
today are "smart" which may mean they have electronics embedded in
them to aid in achieving hits on the desired targets.
[0012] Currently, batteries, and in particular lithium batteries,
are employed in many "smart" munitions. However, since munitions
are produced during periods of non-use and subsequently stockpiled
for use during period of conflict, storage or "shelf life" becomes
an issue. Batteries embedded in such devices should be capable of
long term survival, requiring continued reliably for perhaps
decades in storage. Additionally, the embedded batteries should
retain their capabilities under the most demanding environmental
conditions. The alternative of enabling munitions with a battery
immediately prior to its use is extremely undesirable for combat
situations.
[0013] Published Patent Application No. 2003 0152815 relates
generally to electrical power sources and more particularly to
microscopic batteries some forms of which are integrated or
integratable with and providing internal power to MEMS and
integrated microcircuits, either on a retrofit or original
manufacture basis. MEMS (microelectromechanical systems) involve
the fabrication and use of miniature devices which comprise
microscopic moving parts (such as motors, relays, pumps, sensors,
accelerometers, etc.). MEMS devices can be combined with integrated
circuits, and can perform numerous functions. For example, military
applications for remote sensors and accelerometers include: safing
and arming of fuses; friend or foe identification; embedded sensors
for system integrity monitoring; communications systems monitoring,
such as with satellites; low power mobile displays; flexible
sensing surfaces; and numerous others. For example, the microscopic
batteries of Patent Application No. 2003 0152815 do not employ fuel
cell technology due to the perceived limitation of providing
sufficient power to drive the microdevices.
[0014] U.S. Pat. No. 6,506,513 and U.S. Published Patent
Application No. 20030082421 each disclose a fuel cell assembly in
which the fuel tank is located separate from the fuel cell and
feeds the fuel to the cell via capillary action using a fuel
permeating material; while U.S. Published Patent Application No.
2003 0129464 discloses a fuel cell assembly employing a separate
fuel source which is rupturable by a needle for drawing out the
fuel which is supplied to the fuel cell.
SUMMARY OF THE INVENTION
[0015] One embodiment of this invention is to generate electricity
after having a device in "standby" mode for long periods of time,
i.e. many years. In another embodiment of this invention, a method
of construction of a device that is able to generate electricity
after being in "standby" mode for long periods of time is
discussed. In general, usage in this "standby" mode is called
"shelf life" and batteries have been a primary way to achieve this
goal.
[0016] Although generators could be considered to fit this
definition, their relative size precludes them from all but the
most energy intensive applications, so they are not normally
considered part of this invention, but may be utilized when size is
not a concern. A variety of batteries may fill most short and
medium shelf life niches with little problems. However, it is where
the shelf life requirements go into the decades that batteries
start to have failure issues because of their inherent chemical
nature.
[0017] Thus, in another embodiment of the invention, a fuel cell
may include at least one of the following features or components: a
membrane, and/or storage tanks or cells for hydrogen and oxygen,
and/or an "inertial" switch, which may optionally be assembled in
close proximity to a membrane. The inertial switch, when activated,
may rupture the membrane and allow the hydrogen and oxygen to mix
in a fuel cell.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The Figures illustrates the component Fuel Cell Stack, an
Inertial Switch, and the Polymer Electrolyte Membrane Battery
(PEMERY) of the invention and a conventional fuel cell.
[0019] A more complete appreciation of the present invention, and
one or more of the attendant advantages thereof, will be readily
ascertained and/or obtained as the same becomes better understood
by reference to the following detailed description when considered
in connection with the accompanying drawings, wherein:
[0020] FIG. 1 is an exemplary diagram of a fuel cell stack.
[0021] FIG. 2 is an exemplary diagram of an inertial switch.
[0022] FIG. 3 is an exemplary diagram of a polymer electrolyte
membrane battery (PEMERY).
DETAILED DESCRIPTION OF THE INVENTION
[0023] The micro fuel cell according to one exemplary embodiment is
a new product configured uniquely from several emerging
technologies. One exemplary embodiment also involves the process of
making the new product. The micro fuel cell can include three major
features or components: a polymer electrolyte membrane, or PEM,
and/or a miniature nanotechnology storage tanks or cells for
hydrogen and oxygen to be relied upon by the fuel cell in
generating electricity which may be fracturable, frangible,
rupturable, or puncturable in order to be activated to release the
hydrogen and oxygen, and a miniature or nanotechnology "inertial"
switch, such as a G-force switch or centrifugal-force switch. When
assembled, these three features or components together may present
a very small package uniquely suitable for this application.
[0024] The present invention, in one exemplary embodiment, may
include a fuel cell. Current polymer electrolyte membrane (PEM)
fuel cells have produced cells of 0.2 millimeters in thickness that
can produce better than 0.5 ampere of current per square centimeter
at 0.7 volts. Supporting structures will increase that size, and
the stacking of the cells could be utilized to deliver higher
voltages. Through recent advancements in design, a remarkably small
cell will generate voltages and currents as good as any existing or
proposed battery.
[0025] The elements of this PEM technology have developed to the
point that appropriate and inventive packaging or assembling can be
utilized. One embodiment of this invention depicts the utilization
of such a unique assembly and the method of making such an
assembly. As promising as PEM fuel cell technology is in size
reduction, it is the size that's important, so any future method
developed that also could be miniaturized would also work in this
application.
[0026] In another exemplary embodiment of the present invention, a
method and apparatus for storage of the fuel and oxidant for the
fuel cell is addressed. Fuel cells may use of hydrogen and oxygen
in order to operate. Typically, this supply should be proximate to
the cell structure but, remote storage may work better in some
applications.
[0027] To accomplish this in a miniaturized environment can
require, in one embodiment of the invention, a corresponding
miniaturization of conventional storage "tanks" is preferable.
Alternatively, in another embodiment, these "tanks" may be
constructed from very small blocks of material which are
honeycombed, or otherwise "tunneled."
[0028] In this embodiment, such small blocks of material are
infiltrated with micro channels, cavities, passages, sinuses or
nano-tunnels functioning as one or more storage media. In a
munitions application where a very short active life is required,
material constructed or otherwise provided with micro-cavities or
nano-tunnels affording adequate storage capacity for the hydrogen
and oxygen used to run the fuel cell for a period of time
sufficient to carry out its objectives. Alternatively, in another
exemplary embodiment this device may also be used for standby
power, remote location and for emergency radio beacons as used in
downed aircraft as a few non-limiting examples.
[0029] In another exemplary embodiment of the unique fuel cell
structure and method, a connecting device placed between the PEM
cell assembly and the two gas storage tanks. The purpose of this
connecting device is to serve as a way to deliver the stored
hydrogen and oxygen to the proximity of the power generation
portion of the cells, such that the voltage generation can take
place.
[0030] Many equivalent variations of this connecting device are
possible, such as, for example, chemical, electrical, or mechanical
switches, but a preferred embodiment for the munitions application
involves a mechanical inertial switch.
[0031] An inertial switch is shown in FIG. 2. In this embodiment,
two miniature, sharp, hollow probes 24 and 26 are positioned above
and/or adjacent to membrane 28, located so as to separate a fuel
cell (not pictured) from hydrogen receiver 28 and oxygen receiver
30.
[0032] When sufficient G forces, for example, or any other force
sufficient to activate the switch, are generated, the weight 34
forces probes 24 and 26 through membrane 28. Hydrogen is then able
to flow through hollow probe 24 and oxygen is able to flow through
hollow probe 26 into receivers 30 and 32, respectively, allowing
for the generation of power in a fuel cell stack below the inertial
switch. This is further described in FIG. 3 below.
[0033] Each of these probes (24 and 26) is counterbalanced against
movement. For example, a biasing force may be afforded by a spring
or spring-like element, or a resilient memory material, pneumatic
pressure, or other similar and equivalent means to generally and
continuously (for long periods of time) maintain a first position
adjacent, yet apart, from a respective membrane.
[0034] More recently, delicate, micro-inertia switches have been
developed that may be employed in this structural context. Upon the
imposition of dynamic forces of movement, usually expressed in
terms of G forces, overcoming the biasing force, the probes move
against their respective membranes, thereby rupturing or
penetrating the membranes. In this way, hydrogen and oxygen are
released to flow to the fuel cell region.
[0035] Since many applications of this micro fuel cell technology
involve one-time use, no reset action may be necessary. However, a
reset mechanism and system is an alternative embodiment for either
military or commercial applications. Reset mechanisms can be valves
which may optionally be mechanically or electrically operated by an
operator or by an automated system.
[0036] In another embodiment of the present invention, the fuel
cell and method, prior to activation (either purposeful or in
response to inertial forces), has no active ongoing processes, as
opposed to those that exist with respect to common batteries. Where
batteries are involved, such ongoing processes typically act to
deplete a battery's capacity to perform when ultimately needed. The
sealed hydrogen and oxygen storage tanks of at least one embodiment
of the present invention inhibit active processes from happening
and reduce the problems associated with ongoing processes.
[0037] In the inventive assembly described and illustrated in FIG.
3, the components that run the device and generate electricity,
when needed, are separated by physical barriers. This figure shows
a PEMERY 40 with hydrogen storage tank 42 and the oxygen storage
tank 44 as sealed by membranes 43 and 45, respectively. Inertial
switch 46 is positioned beneath membranes 43 and 45. When
activated, inertial switch 46 will rupture membranes 43 and 45,
allowing the hydrogen from storage tank 42 and the oxygen from
storage tank 44 to flow through inertial switch 46 and into fuel
cell 48. The hydrogen and oxygen undergo an electrochemical
reaction in fuel cell 48, as previously described with respect to
FIG. 1, allowing the conversion into electrical energy, represented
by DC current 50.
[0038] Because the barriers discussed with respect to FIG. 3 are
generally stable by design, the shelf life of the PEMERY unit is
inherently very long. A life period of fifty to sixty years, or
even twice that period, is not unreasonable. Thus, the limitations
of the fuel cell would be reduced to those associated with the
materials utilized in building the fuel cell itself.
[0039] The novel fuel cell and the method for its fabrication may
have applications across a wide range of fields, ranging from
military ordnance systems to commercial signaling devices or
detectors, and to space exploration where a power-up cycle may be
called upon a year or even many years following a launch. Its
miniature size makes the novel fuel cell particularly suitable
anytime and anywhere that space is limited, weight is critical and
time to power-up may be considerably long.
[0040] In some applications, an inertial switch may optionally be
unnecessary. In these applications the inertial switch could be
replaced by another device offering different functionality than
that of the inertial switch. In one exemplary embodiment, the
inertial switch could be replaced with any other on/off device
giving the unit the ability to turn on run for some period and then
turn off again. This would give extended life to a variety of uses,
whether they are military applications or commercial in nature.
[0041] While PEM fuel cell technology is referenced many times
throughout this disclosure, the concept described herein is not
intended to be limited to that technology only. Indeed, as
appropriate to the specific application, any fuel cell technology
would work in this configuration. PEM technology, however, is
presently best adaptable to miniaturization and lower cost.
[0042] Alternatives exist for the gas storage means, as well. The
object is to supply the necessary hydrogen and oxygen to meet the
power design parameters of the product being designed. Just as
power classifications exist among AAA, AA, C and D batteries, this
also is true of the micro fuel cell unit which may be designed
specifically to meet a variety of power demand levels.
[0043] Additionally, the high-G inertial switch designed for
military application could optionally be replaced by a low-G switch
that would allow turning on a battery with a shake of the hand
prior to use. Thus, it is possible, for example, to have a D
battery with no shelf life. However, switching on and off may be
desired, thus necessitating a reset switch incorporated into the
present fuel cell design.
[0044] In another embodiment of the invention, the fuel cell and
inertial switch could be used for driving micropumps for delivering
medicine to remotely located patient, or for activating RB or radio
signal location devices upon sudden impact such as crashes.
[0045] In another exemplary embodiment of the present invention,
the fuel cell and inertial switch can be used for quiescent
tracking or lighting devices that are activated when needed such as
for lost individuals or persons needing emergency medical
attention.
[0046] In yet another exemplary embodiment of the present
invention, the fuel cell and inertial switch can be used in remote
robot devices, even micro-robots, such as on remote missions, i.e.,
arctic exploration or space travel in which devices activated upon
landing.
[0047] While the invention has been particularly shown and
described with reference to a preferred embodiment thereof, it will
be understood by those skilled in the art that various changes in
form and detail may be made without departing from the spirit and
scope of the present invention as set forth in the following
claims. Furthermore, although elements of the invention may be
described or claimed in the singular, the plural is contemplated
unless limitation to the singular is explicitly stated.
* * * * *