Title: System and method for conditioning of intake air for an internal combustion engine
Abstract: A system for conditioning intake air for an internal combustion engine includes an oxygen separation system. The oxygen separation system includes an entry port for ambient air, and at least two separate exhaust ports through which separate exhaust streams are drawn by separate suction sources. The oxygen separation system further includes a plurality of gas-permeable electrodes that are charged to provide a high-voltage static electric field inside the separator. An exhaust stream taken from the anode side of the separator is enriched in oxygen relative to ambient air. This oxygen-enriched stream is provided to an internal combustion engine for use in combusting fuel.
Patent Number: 6,895,945 Issued on 05/24/2005 to Parsa
| Inventors:
|
Parsa; Komad (Laguna Niguel, CA)
|
| Assignee:
|
Parsa Investments, L.P. (Laguna Niguel, CA)
|
| Appl. No.:
|
679993 |
| Filed:
|
October 6, 2003 |
| Current U.S. Class: |
123/539 |
| Intern'l Class: |
F02M 033/00 |
| Field of Search: |
123/3,26,585,536-539,559.1,25 .C,1 A
96/15
|
References Cited [Referenced By]
U.S. Patent Documents
| 3602202 | Aug., 1971 | Kobayashi.
| |
| 3672341 | Jun., 1972 | Smith et al.
| |
| 3792690 | Feb., 1974 | Cooper.
| |
| 3961609 | Jun., 1976 | Gerry.
| |
| 4064840 | Dec., 1977 | Vierling.
| |
| 5051113 | Sep., 1991 | Nemser.
| |
| 5678518 | Oct., 1997 | Grothe et al.
| |
| 5937799 | Aug., 1999 | Binion.
| |
| 6543428 | Apr., 2003 | Blandino et al.
| |
| 6675780 | Jan., 2004 | Wendels et al.
| |
Primary Examiner: McMahon; Marguerite
Attorney, Agent or Firm: O'Melveny & Myers LLP
Parent Case Text
RELATED APPLICATION
This application is a continuation-in-part of application Ser. No. 10/402,279,
filed Mar. 27, 2003, which is incorporated herein by reference and which is a continuation
of Ser. No. 10/194,628, filed Jul. 12, 2002, now U.S. Pat. No. 6,585,809.
Claims
1. A system for conditioning intake air for an internal combustion engine, the
system comprising:
an oxygen separation system operative to separate oxygen from air and to discharge
separate exhaust streams, a first one of the exhaust streams being enriched in
oxygen, wherein the oxygen separation system further comprises a substantially
sealed passageway connecting a first exhaust port for the first exhaust stream
with a second exhaust port for a second exhaust stream, and an entry port into
the passageway between the first exhaust port and the second exhaust ports;
a first suction source connected to the oxygen separation system, configured
to suction the first exhaust stream from the oxygen separation system;
an internal combustion engine receiving the first exhaust stream for use in combustion;
and
a second suction source connected to the oxygen separation system, configured
to suction the second exhaust stream from the oxygen separation system.
2. The system of claim 1, wherein the oxygen separation system further comprises
a first gas-permeable electrode disposed across the passageway, and a second gas
permeable electrode disposed across the passageway.
3. The system of claim 2, wherein the oxygen separation system further comprises
a chamber bounded by the first and second gas-permeable electrodes, the entry port
opening into the chamber.
4. The system of claim 3, wherein the entry port comprises a plurality of small
openings leading into the chamber.
5. The system of claim 2, further comprising a high-voltage source connected
to the first and second gas-permeable electrodes, whereby a static electric field
is maintained between the first and second electrodes.
6. The system of claim 4, wherein the high-voltage source comprises an ignition
coil for the internal combustion engine.
7. The system of claim 1, wherein the oxygen separation system further comprises
at least three gas-permeable electrodes disposed across the passageway between
the first and second exhaust ports.
8. The system of claim 7, further comprising a voltage divider connected to the
at least three electrodes, the voltage divider dividing a voltage output from a
high-voltage source among the at least three electrodes.
9. The system of claim 1, wherein the first suction source comprises an air intake
manifold of the internal combustion engine.
10. The system of claim 1, wherein the oxygen separation system further comprises
an entry port sized to result in a maximum oxygen output from the oxygen separation
system when the internal combustion engine is operating at its peak power speed.
11. The system of claim 1, wherein the first suction source comprises an air pump.
12. The system of claim 1, wherein the first suction source comprises a mechanical pump.
13. The system of claim 1, further comprising a line configured to discharge
the second exhaust streams into an exhaust system for the internal combustion engine.
14. The system of claim 1, wherein the second suction source comprises a vacuum
created using an exhaust stream of the internal combustion engine.
15. The system of claim 1, wherein the second suction source comprises an air pump.
16. The system of claim 1, further comprising an air metering system connected
to the oxygen separation system, the air metering system comprising two inlets,
a mixing section, and an outlet, wherein a first one of the two inlets is connected
to receive the first exhaust stream, and a second one of the two inlets is configured
to receive ambient air.
17. The system of claim 16, wherein the outlet of the air metering system is
connected to an air intake port for the internal combustion engine.
18. The system of claim 17, wherein the air metering system further comprises
a flow control valve configured to control the flow through at least one of the
two inlets.
19. The system of claim 1, further comprising an adjustable valve connected in
series with an entry port of the oxygen separation system.
20. The system of claim 1, further comprising an air filter connected in series
with an entry port of the oxygen separation system.
21. The system of claim 20, further comprising a plenum downstream of the filter,
and a plurality of small openings leading from the plenum into the oxygen separation system.
22. The system of claim 1, further comprising an electronic control system configured
to control total oxygen flow into the internal combustion engine.
23. The system of claim 22, further comprising an oxygen sensor disposed in the
first exhaust streams and connected to provide data to the electronic control system.
24. The system of claim 1, wherein the internal combustion engine comprises a
diesel engine.
25. The system of claim 1, wherein the internal combustion engine comprises a
gasoline engine.
26. A system for conditioning intake air for an internal combustion engine, the
system comprising:
an oxygen separation system operative to separate oxygen from air and to discharge
separate exhaust streams, a first one of the exhaust streams being enriched in
oxygen;
an air metering system connected to the oxygen separation system, the air metering
system comprising two inlets, a mixing section, and an outlet, wherein a first
one of the two inlets is connected to receive the first exhaust stream, and a second
one of the two inlets is configured to receive ambient air;
a first suction source connected to the oxygen separation system, configured
to suction the first exhaust stream from the oxygen separation system;
an internal combustion engine receiving the first exhaust stream for use in combustion;
and
a second suction source connected to the oxygen separation system, configured
to suction a second exhaust stream from the oxygen separation system.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and system for conditioning of intake
air and/or exhaust gases for an internal combustion engine.
2. Description of Related Art
For many combustion engines, including various gasoline and diesel designs, it
is beneficial to supply sufficient air to the combustion chamber for combusting
all of the fuel in the combustion chamber. Complete combustion decreases fuel consumption,
and reduces emissions such as hydrocarbons and carbon monoxide. Achieving complete
combustion, however, requires operating the engine at a leaner air/fuel ratio than
will provide the maximum power output. For example, for most gasoline engines,
an air/fuel ratio of 15:1 to 16:1 yields optimal fuel efficiency, while the stoichiometric
ratio is about 14.7:1, and maximum power is realized between about 12.5:1 and 13.5:1.
Many modern engines control the air/fuel ratio depending on the engine operating
conditions, operating more leanly at low power than at high.
Because combustion engines are limited to a fairly narrow range of optimal
air/fuel ratios, an engine of a given size is limited by its design to a certain
maximum power output. An engine's power is limited by the amount of fuel it can
combust, which is, in turn, limited by the amount of air it takes in (airflow).
The airflow of an engine depends on its displacement, engine speed (e.g., rpm),
and volumetric efficiency. Displacement is generally fixed based on the engine
design. Volumetric efficiency is defined as the amount of air taken in by an engine,
divided by the theoretical maximum amount of air that can be taken in under the
same conditions. It is seldom greater than about 80-85% for a naturally aspirated
gasoline engine, and typically diminishes greatly at high engine speeds. For example,
at 1000 rpm, an engine's volumetric efficiency may be 75%, at 2000 rpm 85%, and
at 3000 rpm 60%.
It is theoretically desirable to have volumetric efficiency as high as 100%,
or
even greater, at all engine speeds. Generally, a well-designed engine with a high
volumetric efficiently can be made lighter than an engine of comparable power having
a lower volumetric efficiency. Volumetric efficiency is often raised using a turbocharger
or supercharger to compress the engine's intake air. Volumetric efficiency can
be increased to greater than 100% using such devices.
However, turbochargers and superchargers have their own disadvantages. For
one thing, such devices are relatively expensive. More fundamentally, using compressed
intake air inevitably results in a higher engine compression ratio than using natural
aspiration in the same engine. This, in turn, causes higher engine stress that
may shorten engine life, and/or may require increasing the mass of engine components
or making other modifications to handle the higher stresses. In gasoline engines,
higher compression ratios often necessitate the use of higher-octane (premium)
gasoline, which is more expensive than regular gasoline. Another disadvantage is
higher combustion temperatures, because the air/fuel mixture experiences increased
compression heating prior to ignition. In turn, higher combustion temperatures
may increase generation of undesired emissions, and in particular, nitrous oxides
(NO
x). Higher combustion temperatures may also increase engine temperature,
shortening the engine life and/or requiring increasing the capacity of the engine's
cooling system or making other modifications to handle the higher temperatures.
Many of the benefits of increased volumetric efficiency, without the disadvantages
associated with compressing intake air, may be realized by enriching intake air
with oxygen. Simply put, using oxygen-enriched intake air can increase the amount
of oxygen available for combustion, without requiring any compression of intake
air. However, there is presently no effective solution for enriching intake air
with oxygen, without drawing oxygen from a finite source such as a bottle. To avoid
the limitations of bottled oxygen, it would be preferable to enrich intake air
with oxygen in a continuous process, using only ambient air as a feedstock. But
present methods of separating oxygen from air are too heavy, too bulky, and/or
two expensive for practical application with most combustion engines. It is desirable,
therefore, to provide an oxygen-enrichment system for a combustion engine that
is sufficiently compact, lightweight and cost-effective for use in many common
engine applications. It is further desirable to provide an internal combustion
engine incorporating an oxygen-enrichment system for conditioning intake air, thereby
attaining benefits similar to turbocharging or supercharging, without the disadvantages
associated with an increased compression ratio.
SUMMARY OF THE INVENTION
The invention provides a method and system for conditioning intake air for an
internal combustion engine, that overcomes the limitations of the prior art. The
method and system achieve oxygen enrichment of intake air, without drawing on any
external source of oxygen. The invention may be implemented using lightweight,
compact, and relatively inexpensive equipment that may be configured for a variety
of different engines. The invention further provides an internal combustion engine
with an intake air conditioning system that may be operated to achieve increased
power, efficiency, and/or reduced emissions, without increasing the pressure of
the intake air.
In an embodiment of the invention, a system comprises an oxygen separation system
connected to supply oxygen-enriched air to the air intake manifold of an internal
combustion engine. The oxygen separation system comprises a substantially sealed
passageway extending between a first exhaust port and a second exhaust port. An
air entry port opens into the passageway, between the first exhaust port and the
second exhaust port. At least two gas-permeable electrodes are disposed inside
the passageway, defining an ionization chamber bounded at opposing surfaces by
an electrode. A high-voltage static electric field may be applied between the opposing
electrodes. When voltage is so applied, air may be drawn through a static electric
field in the ionization chamber, by applying suction to the exhaust ports. The
air entry port is preferably configured such that the ionization chamber is maintained
at a pressure less than atmospheric during operation.
Optionally, more than two gas-permeable electrodes may be provided in
the passageway, dividing it into adjacent sections. These sections may be bounded
by electrodes of the same polarity, or of opposite polarity. At least one section,
however, is bounded by electrodes of opposite polarity. A static electric field
in adjacent sections may be maintained in a uniform direction through the passageway,
by appropriately maintaining the polarity of each section. Essentially, each section
may be configured as an ionization chamber containing an electric field that is
not opposed to the electric field in other sections along the passageway. In the
alternative, some of the sections may be configured as neutral chambers, being
bounded by electrodes of substantially the same charge.
One of the at least two electrodes (an anode) may be positively charged. The
other electrode (cathode) may be negatively charged. The passageway is configured
such that air in the ionization chamber that is closest to the anode is drawn out
the first exhaust port. This air may be enriched in oxygen, such as by having an
oxygen content about 20-40% greater than ambient air. The passageway is further
configured such that air closest to the cathode is drawn out the second exhaust
port. This air may be depleted in oxygen, commensurate with the degree of oxygen
enrichment in the first exhaust stream.
The electric field between the electrodes may cause a portion of the gas to become
ionized. In an embodiment of the invention, the amount of ionization is increased
by exposing the gas in the input space to ionizing radiation, such as from an ultraviolet
lamp or other radiation source. In another embodiment, the electrodes may by themselves
provide adequate ionization, without a further radiation source.
The system further may further include an internal combustion engine having an
air intake manifold connected to receive oxygen-enriched air from the first exhaust
port of the oxygen separation system. During engine operation, engine vacuum may
be used to draw air through the oxygen separation system and its first exhaust
port into the air intake manifold. In the alternative, or in addition, an air pump,
such as a low vacuum pump, may be installed between the first exhaust port and
the air intake manifold. If present, a pump should be configured to suction oxygen-enriched
air through the oxygen separation system, out the first exhaust port, and into
the air intake manifold.
In addition, an air metering system may be installed in the air line between
the
first exhaust port and the air intake manifold, to control the total volume of
air and extent of oxygen enrichment in the air supplied to the engine. If present,
the air metering system may comprise two inlets, a mixing section, and an outlet.
One of its two inlets may be connected to the oxygen separation system and the
other may receive ambient air. The outlet may be connected to the air intake manifold.
A flow control valve or valve may be configured to control the flow through one
or both inlets. The flow control valve may be controlled by an electronic control
system. An oxygen sensor may be placed in the outlet stream of the air metering
system and connected to provide data to the electronic control system. An air pressure
sensor may be similarly placed and connected. The electronic control system may
also be connected to control the pump speed, if a pump is present; and/or to control
the voltage supplied to the electrodes of the oxygen separation system.
The second exhaust port of the oxygen-separation system may be connected to the
engine exhaust, so as to draw air through the oxygen-separation system and out
the second exhaust port. In the alternative, or in addition, a second mechanical
pump may be configured to draw air from the second exhaust port and into the engine
exhaust. In the alternative, the second pump may discharge air from the second
exhaust port into the atmosphere. If present, the second pump may also be controlled
by the electronic control system.
A static high-voltage source may be connected to the electrodes for providing
the
static electric field between the gas-permeable electrodes of the oxygen separation
system. The high-voltage source may be powered by the engine's electrical system.
For example, a continuous high voltage may be drawn from the engine's ignition
system. In the alternative, a separate source may be used. Optionally, the voltage
output from the high-voltage source may be controlled using the electrode control
system. The voltage may vary from zero during engine ignition, up to its maximum
voltage when the engine is operating at maximum power. Up to the point where spark
discharge begins to occur, increasing the voltage supplied to the electrodes should
generally increase the degree of oxygen enrichment from the oxygen separation system.
When the engine is operating at peak power, it will consume the greatest quantity
of fuel, and will reach its maximum requirement for oxygen. Thus, maximum voltage
may be supplied to the electrodes when the engine is operating at peak power. In
the alternative, or in addition, the voltage supply may be held constant and the
degree of oxygen enrichment controlled using the air metering system.
A further alternative, which advantageously may operate without active control,
is to hold the voltage constant and connect the first exhaust port to the engine
vacuum. The ports of the oxygen separator may be configured so that the oxygen
separation system reaches its maximum oxygen output when the engine draws its maximum
vacuum. When voltage is fixed, oxygen output from the oxygen separation system
will generally increase as pressure in the ionization chamber is reduced below
atmospheric. This occurs because ionization of oxygen, and free movement of oxygen
ions towards the anode side, both increase as pressure is reduced. But below a
certain optimal pressure, which will vary depending on the design of the oxygen
separation system, the mass flow of oxygen decreases as the total oxygen throughput
decreases with decreasing pressure. Thus, the system may be designed so that the
optimal pressure is obtained in the oxygen separator—coinciding with maximum
oxygen output—when the engine draws its maximum vacuum.
A more complete understanding of the method and system for conditioning intake
air for an engine will be afforded to those skilled in the art, as well as a realization
of additional advantages and objects thereof, by a consideration of the following
detailed description of the preferred embodiment. Reference will be made to the
appended sheets of drawings which will first be described briefly.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a flow diagram showing exemplary steps of a method for oxygen separation
according to the invention.
FIG. 2 is a diagram showing an exemplary multistage system for oxygen separation.
FIG. 3 is a diagram showing an exemplary multistage system for oxygen separation,
according to an alternative embodiment of the invention.
FIG. 4A is a diagram showing an exemplary combined main air intake and oxygen
separator for use with a combustion engine.
FIG. 4B is a diagram showing an exemplary combined main air intake and oxygen
separator for use with a combustion engine, according to an alternative embodiment
of the invention.
FIG. 5 is a diagram showing an exemplary system for conditioning intake air
for an internal combustion engine.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention provides a method and system for separation of a constituent
from a gaseous mixture. FIG. 1 shows exemplary steps of a method
100 for
conditioning the air intake of an internal combustion engine, according to the
invention. Method
100 may be performed using any of the systems disclosed
herein, or any other suitable equipment. Steps
102-
114 may be performed
continuously and concurrently as a continuous method. At step
102, air is
introduced into an oxygen separation system comprising a passageway connecting
separate exhaust ports, a plurality of gas-permeable electrodes disposed in the
passageway for providing a static electric field through at least a portion of
the passageway, and an entry port into the passageway between the two exhaust ports.
At least two of the electrodes are configured at opposing ends of at least a portion
of the passageway, thereby providing an enclosed ionization chamber. Optionally,
the air pressure is reduced and regulated by a throttle valve in-line with the
entry port. In the alternative, the entry port has a fixed flow capacity. An entry
plenum, having a plurality of small openings leading into the ionization chamber,
may be used to introduce the inlet air under laminar (or less turbulent) flow conditions.
The ionization chamber comprises oppositely-charged electrodes of static polarity
separated by a volume for containing the gaseous mixture. One of the electrodes
is a cathode and the other is an anode.
At step
104, a low pressure is maintained in the ionization chamber. "Low
pressure" refers to a pressure less than atmospheric, such as between about 1-29
inches of mercury vacuum, or between about 0.05 and 0.95 atmospheres. Low pressure
is maintained by controlling the exhaust flows relative to the entry port until
the desired pressure is maintained in the ionization chamber. The optimal pressure
will vary, depending on parameters such as the electrode voltage and spacing.
At step
106, gas between the anode and cathode is ionized. Ionization
may
be driven by an electric field between the anode and cathode, by a separate radiation
source, or by some combination of radiation and an electric field. Depending on
system limitations and application requirements, it is generally desirable to increase
the strength of the electric field to the extent possible without causing arc discharges
to occur. Likewise, increasing the distance between the anode and the cathode may
also aid in the separation of the ionized gases, so long as the electric field
between the electrodes remains sufficiently intense to promote ionization and separation.
As a result of the ionization, oxygen ions are attracted towards the anode, where
they may be neutralized. The balance of the air is either attracted to the cathode,
or is unaffected by the electric field. As a result, air adjacent to the anode
will be enriched in oxygen relative to air adjacent to the cathode.
At step
108, the oxygen-enriched air adjacent to the anode is pumped out
and discharged from the ionization chamber. This may be performed by applying suction
to an exhaust plenum disposed against the anode, using any suitable pump or vacuum
source, including engine vacuum. Similarly, at step
110, oxygen-depleted
air adjacent to the cathode is pumped out and discharged from the ionization chamber.
Again, an exhaust plenum disposed against the cathode and suctioned by a suitable
pump or other vacuum source may be used to remove oxygen-depleted air. The engine
exhaust system may be used to assist in removal of air from the cathode side of
the oxygen separation system. Experimental results showed that oxygen enrichment
in the range of about 30%-40% above ambient levels may readily be achieved in the
exhaust stream from the anode side of the oxygen separator.
At step
112, air that is enriched in oxygen is drawn into the combustion
chamber. The engine may be naturally aspirated. In the alternative, inlet air may
be supplied by a pump or blower such as may be used to reduce the air pressure
in the oxygen separation system. The additional oxygen content may be used to promote
combustion at a lower cylinder pressure than would be possible using a traditional
turbocharger or supercharger. The optimal extent of oxygen enrichment may vary
under different operating conditions, for example, between about 5% and 50% increase
over ambient conditions, although the invention is not limited to this range. It
is believed that the total percentage of oxygen in the combustion chamber should
not be too great for engines designed to operate on air, but will vary depending
on engine design. It should be appreciate that the invention is not limited to
use with ground-based engines, but may also be used for high-altitude applications
such as prop-engine planes and helicopters. The overall efficiency of the system
may actually improve at higher altitudes, as it may become unnecessary to expend
energy for maintaining a reduced air pressure in the ionization chamber.
For many applications, it may be beneficial to control the total amount of oxygen
supplied to the engine. Accordingly, at optional step
114, a suitable control
system is used to control the amount of oxygen supplied depending on engine operating
conditions. For example, under higher load conditions the amount of oxygen supplied
may increase. Various systems may be used to accomplish this step. One example
is a feedback-controlled air metering system that may be used to blend the oxygen
enriched air from the oxygen separation system with ambient air, upstream of the
engine air intake port. An adjustable valve, or any other suitable control mechanism,
may be used to control the proportion of oxygen-enriched air to ambient air in
the inlet stream. Other examples of systems for controlling total oxygen may include
a feedback-controlled voltage control system for controlling the voltage supplied
to the oxygen separation system, and/or a vacuum pump control system for controlling
air flow and pressure through the oxygen control system.
FIG. 2 shows an oxygen separator system
200 according to the invention.
Separator system
200 and its elements are shown in a simplified, diagram
format. One of ordinary skill in the art will be able to select and assemble a
system according to the invention from FIG.
2 and the accompanying description herein.
Oxygen enrichment of greater than 30% was achieved using a system similar
to that shown in FIG.
2. An ionization chamber pressure in the range of
about 1-4 inches Hg below atmospheric pressure (between about 0.85 and 0.95 atmospheres)
was found to be suitable for producing a relatively high mass flow rate of oxygen-enriched
air. No separate source of ionization was needed. The electric field was about
1150 V/in, generated by electrodes of opposite polarity spaced about 4 inches apart
and charged to about 5000 V prior to operation of the system's vacuum pumps. When
the pumps operated, pressure between the electrodes dropped by about 4 inches Hg.
The gas between the electrodes became partially ionized, as evidenced by an approximately
400 V voltage drop across the electrodes after vacuum was applied. Exhaust from
the cathode end of the system was hotter than the ambient air. The increase in
temperature of the cathode-end exhaust was proportional to the electric field power
and voltage drop in the field induced by the vacuum pumps.
Oxygen separator system
200 comprises a section
262c that
serves as an ionization chamber for ionizing a gaseous mixture. The ionization
chamber comprises a space between oppositely-charged, gas permeable electrodes
211a,
213a that bound opposite ends of section
262c
inside of an enclosure
204. The enclosure
204 may have any suitable
shape, and defines a passageway
260 between opposing exhaust ports
218,
220. The gas-permeable electrodes
211a-b and
213a-b
are disposed across the passageway at intervals, thereby providing a plurality
of sections
262a-f each bounded at opposing ends by an electrode.
The sections are disposed in serial fashion through most of the passageway, terminating
at end sections
224,
226.
FIG. 2 shows a cutaway view of a cylindrical enclosure
204 defining passageway
260. Enclosure
204 may be made of any suitable non-conductive material,
for example, plastic. To save space or to fit in a particular location, the enclosure
may be curved or contoured along its length. In a prototype embodiment of the invention,
enclosure
204 comprised a 14-inch length of ASTM D3034, 8-inch diameter
PVC pipe, with its ends sealed by metal plates.
Enclosure
204 is provided with at least three gas ports connecting
with passageway
260: entry port
216, exhaust port
218, and
exhaust port
220. System
200 further comprises two gas-permeable
electrode banks
210,
212 (an anode bank and a cathode bank) spaced
apart and insulated from one another. The electrode banks are separated from each
other by the ionization chamber
202. Each bank is comprised of a series
of parallel spaced electrodes. Bank
210 is comprised of electrodes
211a-c,
and bank
212 is comprised of electrodes
213a-c. The electrodes
may be formed of any suitable conductive and gas-permeable material. Each electrode
within a bank of electrodes may be maintained at the same voltage. For example,
electrodes
211a-c may be maintained at the same positive voltage,
and electrodes
213a-c may be maintained at the same negative voltage.
Entry port
216 is configured for discharging air directly into the space
262c between electrode banks
210,
212. Entry port
216
may be comprised of a plurality of small orifices that serve as an entry plenum
to reduce the turbulence of air admitted into the ionization chamber
262c.
In the illustrated embodiment, the entry port
216 is open to the environment,
to admit ambient air. In the alternative, the entry port may be surrounded by a
plenum (not shown) for control of the entry air. The plenum may have an inlet that
is connected in series with an adjustment valve (not shown). Yet another alternative
is to provide a discrete entry port into the ionization chamber, with or without
a series-connected entry valve. In a prototype embodiment, a single discrete entry
port about 0.75 inches in diameter was used, without an adjustment valve. If present,
an adjustment valve may be used to throttle air flow into the ionization chamber,
thereby providing for regulation of air pressure in section
262c (ionization
chamber). If no entry valve is provided, pressure may be controlled by controlling
the speed of the exhaust pumps, or by providing an adjustment valve on one or more
of the exhaust ports.
Referring again to FIG. 2, ionization may be driven entirely by an electric
field that is created between electrode banks
210 and
212, by connection
to a high-voltage source
242. It may be desirable to increase the strength
of the electric field up to but not exceeding a level that will result in arc discharge.
A higher electric field strength may result in a higher level of ionization, as
well as more efficient separation of oppositely-charged ions. Use of an ionizing
radiation source (not shown) in the ionization chamber may permit lower electrode
voltages to be used, all other things being equal. The ionization chamber
262c
should be configured to produce negative ions predominately comprised of O
2-,
and positive ions predominately comprised of N
2+.
Electrode banks
210,
212 may be configured in various ways.
In an embodiment of the invention, each of their constituent electrodes
211a-c
and
213a-c are conductive plates. For example, the electrodes
may be aluminum or copper plates. In a prototype embodiment, the electrodes comprise
thin circular aluminum plates perforated by equally-spaced holes. The electrode
plates are oriented parallel to one another, and are mounted within enclosure
204
so as to divide the enclosure into a central enclosed volume (ionization chamber)
262c between the electrodes, and two exhaust plenums
224,
226, as shown in FIG.
2. Each electrode is gas-permeable to provide
for fluid communication between the exhaust plenums
224,
226 and
the ionization chamber
262c between the electrodes.
Electrode banks
210,
212 should be spaced apart far enough
so that gas adjacent to one electrode bank, e.g., bank
210, is not likely
to be suctioned into the exhaust plenum belonging to the opposite electrode, e.g.,
plenum
226 of electrode bank
212. At the same time, the electrode
banks should not be spaced too far apart, as this will weaken the electric field
and make separation of ions less likely. In other words, in selecting an appropriate
spacing and configuration of the electrode, the fluid dynamics created by pump
suction should be considered as well as the electric field between the electrodes.
In a prototype embodiment, the electrode banks were spaced approximately 4 inches
apart and were positioned symmetrically with respect to the center of the enclosure
204. Each electrode in the respective banks was positioned approximately
1.5 inches away from other electrodes in the same bank. A space of approximately
2 inches was provided between each electrode bank and its nearest exhaust port
for each exhaust plenum
224,
226.
Pumps
228,
238 may be connected to exhaust ports
218,
220, and may be operated to create suction in exhaust plenums
224,
226, respectively. Engine vacuum may be used instead of, or in addition
to, pumps
228,
238. Any suitable vacuum or suction pump may be used,
depending on the intended mass flow rate through the system, the desired vacuum
pressure in chamber
262c, and the electric field voltage. In a prototype
embodiment, pumps
228,
238 comprised 145 mm 2-stage tangential bypass
discharge vacuum pumps from Ametek® Lamb Electric of Kent, Ohio.
The flow of air into and out of system
200 may be controlled by an intake
valve (not shown), exhaust valve (not shown), and/or by varying the speed of pumps
228,
230. Air may be drawn into the ionization chamber
262c
as shown by arrow
236, because of suction provided by pumps
228
and
230 or from engine vacuum air within the chamber
262c is
ionized by the electric field between electrode banks
210,
212, and
ions of opposite polarity tend to propagate in opposite directions, towards an
oppositely-charged one of the electrode banks. An oxygen-enriched portion of the
air passes through electrode bank
210, and is discharged through exhaust
port
218, as indicated by arrow
230. The balance of air flow passes
through electrode bank
212 and is discharged through exhaust port
220,
as indicated by arrow
240. Provided that chamber
102 is substantially
sealed except for the gas ports, the inlet mass flow rate
236 will equal
the sum of the exhaust flows
230,
240.
An electric field of static polarity is maintained between electrode banks
210,
212 by DC power source
242. Any suitable source of direct current
(DC) power may be used, such as a discrete power supply. Power source
242
should be capable of maintaining the desired electrode voltage across the electrodes
at a sustained power level. In a prototype embodiment, a DC-to-DC power converter,
model SC-50 10 Watt, by American High Voltage of Elko, Nev., was used as a high
voltage source
242. The power converter was designed to produce an output
voltage of 0-5000 VDC, in proportion to an input voltage of 0-12 VDC. The power
converter was powered by a AC-to-DC 9 V power supply
244, rated for 1200
mA maximum output. Power supply
244 was connected to ordinary 115 VAC household
current
246. The output voltage of high voltage source
242 was nominally
5000 VDC prior to operation of the exhaust pumps. Although well below the voltage
threshold for arc discharge, the voltage proved sufficient for attaining useful
results in the separation of oxygen from air. Power dissipated by source
242
is believed to have been less than ten Watts.
For a given configuration of electrodes and voltage supplied to the electrodes,
the voltage of the electric field may be related to the mass flow of ionized air
through the ionization chamber. Using an apparatus of the type shown in FIG. 2
open to an ambient air environment, a voltage difference between the electrodes
may decrease from an initial voltage measured when the ionization chamber is at
atmospheric pressure. As gas is pumped out from the chamber, pressure in the chamber
will be reduced if the entry port is sufficiently restricted. Surprisingly, the
voltage difference between the electrodes will decrease as the exhaust pump speed
is increased, until a certain vacuum level is obtained in the ionization chamber.
That is, the maximum voltage drop is a function of the pump speed and input flow
rate. If an input valve is in place on the entry port, as the valve is increasingly
restricted, the maximum voltage drop will be observed at progressively slower pump
speeds. The extent of voltage drop will depend on the characteristics of the voltage
source, and is believed related to an electric current created by ionized gas flow
between the electrodes. At pressures below the vacuum level at which a maximum
voltage drop is observed, the voltage difference will again increase as the mass
flow of gas between the electrodes decreases.
In a prototype system of the type shown in FIG. 2, the exhaust pumps described
above were operated at their full design speed, drawing through a single entry
port about 0.75 inches in diameter. In this mode, a pressure drop of about 5 inches
Hg below atmospheric was measured by gauge
232. An oxygen sensor capable
of reading percentage of oxygen in the range of 0-100% was positioned in the exhaust
port of exhaust pump
228. The sensor was adjusted to read a concentration
of 20% oxygen in ambient air, prior to placing in the exhaust port. Voltage drop
at the voltage source
242 stabilized at about 400 V during operation of
the pumps. Oxygen content stabilized at a level of about 26% total oxygen at the
exhaust pump
240. Hence, the prototype successfully enriched the oxygen
content of the exhaust by about 30%, relative to ambient levels. It is believed
that greater oxygen enrichment is also possible, by implementing the features of
the inventions disclosed herein.
FIG. 3 shows an alternative system
300 for oxygen separation. Like system
200, system
300 includes a generally tubular enclosure
304
housing a plurality of permeable electrodes
310a-f in a passageway
360, an entry port
316 and two exhaust ports
218,
220
disposed at opposite ends of the passageway. Electrodes
310a-f are
disposed across passageway
360, dividing it into a plurality of sections
each bounded on opposing ends by an electrode. Differences from system
200
include tapered exhaust ports
318,
320 to promote laminar flow, a
voltage divider circuit
350, exhaust control valves
352,
354,
and controller
356. It should be appreciated that system
300 exemplifies
various new features and modifications to system
200, and it is not necessary
that all of these new features be used together at once. An oxygen separation system
according to the invention may be constructed by selecting from these new features
and modifications as desired.
Each electrode
310a-f may be connected to a different node of
voltage divider circuit
350. Resistors R
1 may be of equal value,
and divide the output of high voltage source
342 into equal (or if desired,
unequal) increments. High voltage source
342 is any suitable source of high-voltage
DC current. Resistor R
2 should be of comparatively high impedance relative
to the sum of the impedances of resistors R
1, so that substantially all
of the voltage output of source
342 is available between the resistors R
1.
R
2 should also be resistive enough to prevent unnecessary dissipation of
power by circuit
350. Thus, for example, if voltage source
342 provides
an output voltage of 50,000 V, this may be divided equally by resistors R
1
into increments of 10,000 V each. Electrode
310a, when connected
to circuit
350 as shown, will be the most negatively charged of electrodes
310a-f. Electrode
310b will be 10,000 V more positive
than electrode
310a, while being 10,000 V more negative than electrode
310c; and so on down the sequence of electrodes to the most positive
electrode
310f. Any other suitable voltage divider circuit may be
used; for example, multiple high-voltage sources may be connected in series, with
their connection nodes and end nodes dividing the sum of their voltage output.
Thus, an electric field of approximately uniform magnitude may be generated
along the length of passageway
360. This relatively long high-voltage electric
field should enhance ionization of oxygen, as well as separation of ionized oxygen
from air. In effect, the space between adjacent electrodes may be used as an extension
of the ionization chamber
302. The electric field between individual electrodes
may be made as strong as desired, up to the threshold imposed by arcing. The total
voltage drop across the bank of electrodes
310a-f may therefore be
greater than would be possible using just two oppositely-charged electrode banks
of equivalent spacing. In addition, just as in system
200, the presence
of additional electrodes in the gas flow path may enhance net diffusion of ionic
species towards an oppositely charged electrode, and reduce backwards diffusion.
A still further advantage is that the tubular enclosure
304 may readily
be curved, coiled or contoured along its length to fit in a desired space, and
the static electric field required for separation of ionic species may be maintained
along a curved flow path by placing electrodes at sufficiently close intervals
along the curve.
Oxygen separation systems
300 or
200 may function without dedicated
exhaust pumps in a system that includes an independent source of suction, e.g.,
an internal combustion engine. Hence, referring again to FIG. 3, system
300
is depicted without exhaust pumps. It should be appreciated, however, that suction
should be applied to both exhaust ports
318,
320, thereby drawing
gas in through entry plenum
316, for system
300 to operate in a manner
similar to that described for system
200. Flow through system
300
may be controlled by valves
352,
354 connected in series with one
or more of the exhaust ports. Exhaust port
318 may have a higher flow capacity
than port
320, depending the intended purity of separation. For example,
if 30% oxygen enrichment is desired, a ratio of 3:1 in the flow capacity of port
318 to
320 may be useful.
Oxygen separation system
300 may be configured for electronic control,
for example by an engine control module, and/or by a dedicated controller
356.
There are, of course, various ways that system
300 may be configured for
automatic control. One approach may be to connect a controller
356, such
as a programmable processor or controller, to sensors capable of measuring useful
operating parameters. For example, controller
356 may be connected to an
oxygen or other gas sensor
358 located in or near one of the exhaust plenums
326 or ports
354. In addition, or in the alternative, voltage drop
of the divider circuit
350 may be measured. Generally, given a unvarying
voltage supply, a voltage drop will be proportional to degree of ionization and
gas separation. Another input may be provided by connecting to a pressure sensor
332 inside enclosure
304, such as near or in the ionization chamber
302. Controller
356 may be connected to control one or more of the
exhaust valves
352,
354, whereby flow through system
300 may
be controlled independently from a more complex system to which it may belong.
In the alternative, or in addition, controller
356 may communicate with
the engine control module to coordinate control of oxygen separation system
300
with the engine system.
An oxygen separation system of the type described above may readily be incorporated
into an airflow system such as found in many conventional combustion engines. For
example, FIG. 4A shows an integrated air intake and oxygen separation system
400.
System
400 comprises a main air intake
402 for holding an air filter
404 upstream and in series with an entry port
406 of an oxygen separation
system
410. Main air intake
402 may be configured to provide a plenum
405 downstream of the filter
404 and surrounding the entry port
406.
Entry port
406 may comprise a plurality of small openings. The total area
of entry port
406 may be configured so that maximum total oxygen is output
from the anode-side exhaust port
408 when the oxygen-enriched exhaust stream
409 reaches its maximum flow rate, which should occur when the internal
combustion engine is operating at maximum power.
Oxygen separator
410 further comprises cathode-side exhaust port
412
from which an oxygen-depleted exhaust stream
413 may be drawn. An air passageway
414 is disposed along an interior of the oxygen separator, connecting the
anode-side and cathode-side exhaust ports
408,
412. Passageway
414
may be divided into sections by a plurality of electrodes, e.g., electrodes
416,
417. Any number of the sections may be configured as an ionization/separation
chamber by appropriately charging the electrodes using a high voltage source
418
connected to a power source
420. For automotive applications, high voltage
source
418 may comprise an ignition coil, and power source
420 may
comprise the battery and charging system.
An ambient air supply port
424 may be provided in housing
401 of
main air intake
402, opening into plenum
405. An adjustable control
valve
426 may be configured to control ambient air stream
427. It
should be apparent that valve
426 need not be incorporated into housing
402. Ambient air stream
427 and oxygen-enriched air stream
409
may be combined by a downstream air metering system (not shown). In the alternative,
port
424 may be omitted, and all engine air may be drawn from the oxygen-enriched
port
408. Yet another alternative is to blend oxygenated exhaust stream
409 with a portion of oxygen-depleted stream
413, with or without
the addition of ambient air stream
427, for control of total oxygen.
Housing
401 may be made from any suitable material, such as any suitable
plastic currently used for filter housings. Likewise, housing
422 for passageway
414 may be made from the same material, or from any similar or compatible
material, as housing
401. These materials may include any suitable non-conductive
plastic material that will maintain its shape and structural integrity in the heat
of the engine compartment.
FIG. 4B shows a combination air intake and oxygen separation system
450
like system
400, differing in that main air intake
430 is connected
to oxygen separation unit
440 via a discrete port
432 controlled
by an adjustable valve
434. Valve
434 may be used to maintain a desired
pressure and/or flow rate through oxygen separator
440. The presence of
a valve may be particularly useful if the amount of suction applied to port
442
and/or port
448 varies under different engine conditions. For example, valve
434 may be opened as engine speed increases, maintaining a relatively constant
pressure in separator
440 under different operating conditions.
FIG. 5 shows an exemplary system
500 for conditioning intake air for
an internal combustion engine
508. Air flow is indicated by bold dark arrows.
Communication lines between system components are indicated by solid lines of regular
weight. System
500 comprises a main air intake
502 through which
intake air may be drawn. Air intake
502 optionally includes any suitable
air filter
504 and a plenum
506.
Intake air may be drawn into an intake port
512 of oxygen separator
510, which may be of any suitable type described herein. Optionally, an
adjustable control valve
505 is placed upstream and in series with intake
port
512, to control flow into separator
510. Valve
505 may
be continuously adjusted to maintain a desired pressure in separator
510,
while the mass flow rate from separator
510 into engine
508 may be
allowed to vary according to engine requirements. In the alternative, or in addition,
intake port
512 may comprise a plurality of small openings leading from
a plenum (such as plenum
506) into the oxygen separation system
510,
or any other suitable opening.
A high voltage may be supplied to separator
510 using a high voltage source
519. High voltage source
519 may comprise any suitable high voltage
source as known in the art. It may be powered by the engine
508 electrical
system. For example, a portion of system
519 may comprise a high-voltage
ignition system for engine
508.
Oxygen-enriched air may be drawn from an anode-side exhaust port
of separator
510 and into an intake manifold
516 of engine
508.
The oxygen-enriched air stream may be drawn directly into the intake manifold by
the engine vacuum. In the alternative, any suitable vacuum pump
518 may
be interposed between the oxygen separator
510 and intake manifold
516,
to boost the amount of suction applied at the anode-side exhaust port
514
of separator
510. Vacuum pump
518 may be driven by its own motor,
or may be driven by the engine
508 drive shaft or exhaust pressure, in the
manner of a turbocharger or supercharger. Output from the vacuum pump
518
may be at any desired pressure, for example, at or above atmospheric pressure.
An output pressure near atmospheric may be advantageous in reducing engine stress
and increasing efficiency, as explained above.
In addition, or in the alternative, an air metering system
520 may be
interposed
between separator
510 and engine intake
516. Air metering system
520 may be used to control the total volume of air and oxygen content of
air supplied to engine
508. Metering system
520 may comprise a first
intake port
522 for oxygen-enriched air from separator
510, a second
inlet port
524 for ambient air from main air intake
502, at least
one adjustable control valve
526 to control the relative proportions of
air drawn through its inlet ports, and a mixing section
528 wherein air
drawn through the at least two inlet ports
522,
525 may be blended
together. In addition, or in the alternative, a stream of oxygen-depleted air may
be taken from cathode-side exhaust port
515 of separator
510, and
mixed with the oxygen-enriched air from port
514, as engine conditions dictate.
Oxygen-depleted air may be drawn from exhaust port
515 of
separator
510 using engine vacuum generated at the exhaust manifold
517
of engine
508. For example, air may be drawn into the exhaust system using
a pulsed secondary air injection system ("PAIR system"), a venturi vacuum pump,
or any other suitable exhaust-driven pump. In addition, or in the alternative,
a vacuum pump
532 may be used to draw air out port
515. Like vacuum
pump
518, vacuum pump
532 may be driven by its own motor, or may
be driven by the engine
508 drive shaft or exhaust pressure, in the mann
