U.S. patent application number 17/666913 was filed with the patent office on 2022-05-26 for system and method of desorbing nitrogen from particles.
This patent application is currently assigned to Inova Labs, Inc.. The applicant listed for this patent is Inova Labs, Inc.. Invention is credited to Dragan NEBRIGIC.
Application Number | 20220161274 17/666913 |
Document ID | / |
Family ID | |
Filed Date | 2022-05-26 |
United States Patent
Application |
20220161274 |
Kind Code |
A1 |
NEBRIGIC; Dragan |
May 26, 2022 |
SYSTEM AND METHOD OF DESORBING NITROGEN FROM PARTICLES
Abstract
Described herein are various embodiments of an oxygen
concentrator system. In some embodiments, oxygen concentrator
system includes one or more components that improve the useful
lifetime of gas separation adsorbents.
Inventors: |
NEBRIGIC; Dragan; (Austin,
TX) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Inova Labs, Inc. |
San Diego |
CA |
US |
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Assignee: |
Inova Labs, Inc.
San Diego
CA
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Appl. No.: |
17/666913 |
Filed: |
February 8, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16076177 |
Aug 7, 2018 |
11266998 |
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PCT/US2017/016950 |
Feb 8, 2017 |
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17666913 |
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62292585 |
Feb 8, 2016 |
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International
Class: |
B03C 3/41 20060101
B03C003/41; B01D 53/04 20060101 B01D053/04; B01D 53/047 20060101
B01D053/047; B03C 3/38 20060101 B03C003/38 |
Claims
1. A system comprising: an oxygen concentrator apparatus comprising
a canister, the canister having a gas separation adsorbent disposed
therein; and an ionization module comprising: an ionizer configured
to ionize a stream of ambient air, the ionizer comprising an inlet
through which the stream of ambient air enters the ionizer and an
outlet through which the ionized stream of ambient air exits the
ionizer; and a connector configured to removably couple the
ionization module to the oxygen concentrator apparatus.
2. The system of claim 1, wherein the connector is configured to
removably couple the ionization module to the oxygen concentrator
apparatus such that the ionized stream of ambient air is delivered
to the canister of the oxygen concentrator apparatus.
3. The system of claim 2, wherein the oxygen concentrator apparatus
is configured to deliver the ionized stream of ambient air to the
canister during a venting process to remove contaminants from the
gas separation adsorbent disposed therein.
4. The system of claim 1, wherein the oxygen concentrator apparatus
further comprises a pump configured to pressurize the ionized
stream of ambient air.
5. The system of claim 1, wherein the oxygen concentrator apparatus
further comprises a particulate filter.
6. The system of claim 1, wherein the oxygen concentrator apparatus
is a portable oxygen concentrator apparatus.
7. The system of claim 1, wherein the ionization module further
comprises a pump configured to pressurize the ionized stream of
ambient air.
8. The system of claim 7, wherein the ionization module further
comprises a control board configured to send control signals to the
ionizer and the pump.
9. The system of claim 8, wherein the control board of the
ionization module comprises a screen for displaying information
regarding a status of the ionization module.
10. The system of claim 1, wherein the connector of the ionization
module comprises tubing for delivering the ionized stream of
ambient air to the canister of the oxygen concentrator
apparatus.
11. The system of claim 1, wherein the ionization module further
comprises a housing in which the ionizer is disposed.
12. A method comprising: removably coupling, with a connector, an
ionization module to an oxygen concentrator apparatus, wherein the
oxygen concentrator apparatus comprises a canister having a gas
separation adsorbent disposed therein; and ionizing, with an
ionizer of the ionization module, a stream of ambient air, wherein
the ionizer comprises an inlet through which the stream of ambient
air enters the ionizer and an outlet through which the ionized
stream of ambient air exits the ionizer.
13. The method of claim 12 further comprising: receiving, at the
canister of the oxygen concentrator apparatus, the ionized stream
of ambient air from the ionization module.
14. The method of claim 13 further comprising: passing the ionized
stream of ambient air through the canister of the oxygen
concentrator apparatus during a venting process to remove
contaminants from the gas separation adsorbent disposed
therein.
15. The method of claim 12 further comprising: pressurizing, with a
pump of the oxygen concentrator apparatus, the ionized stream of
ambient air.
16. The method of claim 12 further comprising: filtering, with a
particulate filter of the oxygen concentrator apparatus, the
ionized stream of ambient air.
17. The method of claim 12 further comprising: pressurizing, with a
pump of the ionization module, the ionized stream of ambient
air.
18. The method of claim 17 further comprising: sending, with a
control board of the ionization module, control signals to the
ionizer and the pump.
19. The method of claim 18 further comprising: displaying, with a
screen of the control board, information regarding a status of the
ionization module.
20. The method of claim 12 further comprising: disconnecting the
ionization module from the oxygen concentrator apparatus.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S.
application Ser. No. 16/076,177, filed Aug. 7, 2018, which is a
national phase entry under 35 U.S.C. .sctn. 371 of International
Application No. PCT/US2017/016950, filed Feb. 8, 2017, published in
English, which claims priority from U.S. Application No.
62/292,585, filed Feb. 8, 2016, all of which are incorporated
herein by reference.
TECHNICAL FIELD
[0002] The present invention relates generally to health equipment
and, more specifically, to oxygen concentrators.
BACKGROUND
[0003] There are many patients that require supplemental oxygen as
part of Long Term Oxygen Therapy (LTOT). Currently, the vast
majority of patients that are receiving LTOT are diagnosed under
the general category of Chronic Obstructive Pulmonary Disease,
COPD. This general diagnosis includes such common diseases as
Chronic Asthma, Emphysema, Congestive Heart Failure and several
other cardio-pulmonary conditions. Other people (e.g., obese
individuals) may also require supplemental oxygen, for example, to
maintain elevated activity levels.
[0004] Doctors may prescribe oxygen concentrators or portable tanks
of medical oxygen for these patients. Usually a specific oxygen
flow rate is prescribed (e.g., 1 liter per minute (LPM), 2 LPM, 3
LPM, etc.). Experts in this field have also recognized that
exercise for these patients provide long term benefits that slow
the progression of the disease, improve quality of life and extend
patient longevity. Most stationary forms of exercise like tread
mills and stationary bicycles, however, are too strenuous for these
patients. As a result, the need for mobility has long been
recognized. Until recently, this mobility has been facilitated by
the use of small compressed oxygen tanks. The disadvantage of these
tanks is that they have a finite amount of oxygen and they are
heavy, weighing about 50 pounds, when mounted on a cart with dolly
wheels.
[0005] Oxygen concentrators have been in use for about 50 years to
supply patients suffering from respiratory insufficiency with
supplemental oxygen. Traditional oxygen concentrators used to
provide these flow rates have been bulky and heavy making ordinary
ambulatory activities with them difficult and impractical.
Recently, companies that manufacture large stationary home oxygen
concentrators began developing portable oxygen concentrators, POCs.
The advantage of POCs concentrators was that they can produce a
theoretically endless supply of oxygen. In order to make these
devices small for mobility, the various systems necessary for the
production of oxygen enriched gas are condensed.
BRIEF SUMMARY
[0006] Systems and methods of providing an oxygen enriched gas to a
user of an oxygen concentrator are described herein.
[0007] In some embodiments, an oxygen concentrator includes at
least one canister; gas separation adsorbent disposed in at least
one canister, at least two electrodes coupled to at least one
canister, and a power supply coupled to at least one of the
electrodes. The gas separation adsorbent separates at least some
nitrogen from air in the canister to produce oxygen enriched gas.
The power supply is configured to electrically excite at least one
of the electrodes such that current flows between the electrodes
and ionizes air between the two electrodes. The ionized air assists
in removal of at least one compound from the gas separation
adsorbent. At least one compound is water and/or bacteria.
[0008] In some embodiments, a method of treating gas separation
adsorbent of an oxygen concentrator includes providing electrical
current to a first electrode such that electrical current flows
from the first electrode to a second electrode; the electrical
current flowing through at least a portion of the gas adsorbent and
ionizing air in the gas separation adsorbent; and removing one or
more compounds from the ionized gas separation adsorbent.
[0009] In some embodiments, a method of treating gas separation
adsorbent in an oxygen concentrator includes providing air to the
gas separation adsorbent, providing electrical current to a first
electrode such that electrical current flows from the first
electrode to a second electrode; the electrical current flowing
through at least a portion of the gas adsorbent and ionizing at
least a portion of the provided air, and removing one or more
compounds from the gas separation adsorbent.
[0010] A method of operating an oxygen concentrator system includes
providing at least two electrodes to at least one canister of a
first oxygen concentrator of the oxygen concentrator system, the
gas canister comprising gas separation adsorbent. Electrical
current is to a first electrode of the two electrodes such that
electrical current flows from the first electrode to a second
electrode of the two electrodes. The electrical current flows
through at least a portion of a gas adsorbent for a period of time.
The canister after the period of time has elapsed is provided to a
second oxygen concentrator of the oxygen concentrator system.
[0011] A method of providing oxygen enriched gas to a user of an
oxygen concentrator system, includes automatically assessing a
state of the gas separation adsorbent and operating the power
supply at a voltage sufficient to electrically excite at least one
of the electrodes such that current flows between the electrodes
and ionizes the gas separation adsorbent.
[0012] In an embodiment, an ionization module is used to produce
ionized gas. An ionization module, in one embodiment, includes an
ionizer capable of producing ionized gas, the ionizer comprising an
ionizer outlet through which ionized gas produced by the ionizer
exits. The ionization module may, optionally, include a pump
coupled to the ionizer outlet. The ionizer includes a coupling
which is configured to couple the ionizer to a gas separation
adsorbent canister.
BRIEF DESCRIPTION OF DRAWINGS
[0013] Advantages of the present invention will become apparent to
those skilled in the art with the benefit of the following detailed
description of embodiments and upon reference to the accompanying
drawings in which:
[0014] FIG. 1 depicts a schematic diagram of an embodiment of the
components of an oxygen concentrator;
[0015] FIG. 2 depicts a schematic diagram of an embodiment of the
outlet components of an oxygen concentrator;
[0016] FIG. 3 depicts a schematic diagram of an embodiment of an
outlet conduit for an oxygen concentrator;
[0017] FIG. 4 depicts a perspective view of an embodiment of a
dissembled canister system;
[0018] FIG. 5 depicts a perspective view of an embodiment of an end
of a canister system;
[0019] FIG. 6 depicts the assembled end of an embodiment of the
canister system end depicted in FIG. 5;
[0020] FIG. 7 depicts a perspective view of an embodiment of an
opposing end of the canister system depicted in FIGS. 4 and 5;
[0021] FIG. 8 depicts a perspective view of an embodiment of the
assembled opposing end of the canister system end depicted in FIG.
7;
[0022] FIG. 9 depicts various profiles of embodiments for providing
oxygen enriched gas from an oxygen concentrator;
[0023] FIG. 10 depicts a perspective view of an embodiment of a
canister that includes at least two electrodes in a canister;
[0024] FIG. 11 depicts a top view of an embodiment of the canister
of FIG. 12 containing gas separation adsorbent;
[0025] FIG. 12 depicts a perspective view of an embodiment of a
canister that includes at least two electrodes;
[0026] FIG. 13 depicts an exploded view of an ionization
module;
[0027] FIG. 14 depicts a schematic diagram of the interconnection
of the components of an ionization module;
[0028] FIG. 15 depicts a schematic diagram of an alternate
interconnection of the components of an ionization module; and
[0029] FIG. 16 depicts a projection view of an ionization
module.
[0030] While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof are shown by
way of example in the drawings and will herein be described in
detail. It should be understood, however, that the drawings and
detailed description thereto are not intended to limit the
invention to the particular form disclosed, but on the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the present
invention as defined by the appended claims.
DETAILED DESCRIPTION
[0031] It is to be understood the present invention is not limited
to particular devices or methods, which may, of course, vary. It is
also to be understood that the terminology used herein is for the
purpose of describing particular embodiments only, and is not
intended to be limiting. Headings are for organizational purposes
only and are not meant to be used to limit or interpret the
description or claims. As used in this specification and the
appended claims, the singular forms "a", "an", and "the" include
singular and plural referents unless the content clearly dictates
otherwise. Furthermore, the word "may" is used throughout this
application in a permissive sense (i.e., having the potential to,
being able to), not in a mandatory sense (i.e., must). The term
"include," and derivations thereof, mean "including, but not
limited to."
[0032] The term "coupled" as used herein means either a direct
connection or an indirect connection (e.g., one or more intervening
connections) between one or more objects or components. The phrase
"connected" means a direct connection between objects or components
such that the objects or components are connected directly to each
other. As used herein the phrase "obtaining" a device means that
the device is either purchased or constructed.
[0033] Oxygen concentrators take advantage of pressure swing
adsorption (PSA). Pressure swing adsorption involves using a
compressor to increase gas pressure inside a canister that contains
particles of a gas separation adsorbent. As the pressure increases,
certain molecules in the gas may become adsorbed onto the gas
separation adsorbent. Removal of a portion of the gas in the
canister under the pressurized conditions allows separation of the
non-adsorbed molecules from the adsorbed molecules. The gas
separation adsorbent may be regenerated by reducing the pressure,
which reverses the adsorption of molecules from the adsorbent.
Further details regarding oxygen concentrators may be found, for
example, in U.S. Published Patent Application No. 2009-0065007,
published Mar. 12, 2009, and entitled "Oxygen Concentrator
Apparatus and Method", which is incorporated herein by
reference.
[0034] Ambient air usually includes approximately 78% nitrogen and
21% oxygen with the balance comprised of argon, carbon dioxide,
water vapor and other trace elements. If a gas mixture such as air,
for example, is passed under pressure through a vessel containing a
gas separation adsorbent bed that attracts nitrogen more strongly
than it does oxygen, part or all of the nitrogen will stay in the
bed, and the gas coming out of the vessel will be enriched in
oxygen. When the bed reaches the end of its capacity to adsorb
nitrogen, it can be regenerated by reducing the pressure, thereby
releasing the adsorbed nitrogen. It is then ready for another cycle
of producing oxygen enriched air. By alternating canisters in a
two-canister system, one canister can be collecting oxygen while
the other canister is being purged (resulting in a continuous
separation of the oxygen from the nitrogen). In this manner, oxygen
can be accumulated out of the air for a variety of uses include
providing supplemental oxygen to patients.
[0035] FIG. 1 illustrates a schematic diagram of an oxygen
concentrator 100, according to an embodiment. Oxygen concentrator
100 may concentrate oxygen out of an air stream to provide oxygen
enriched gas to a user. As used herein, "oxygen enriched gas" is
composed of at least about 50% oxygen, at least about 60% oxygen,
at least about 70% oxygen, at least about 80% oxygen, at least
about 90% oxygen, at least about 95% oxygen, at least about 98%
oxygen, or at least about 99% oxygen.
[0036] Oxygen concentrator 100 may be a portable oxygen
concentrator. For example, oxygen concentrator 100 may have a
weight and size that allows the oxygen concentrator to be carried
by hand and/or in a carrying case. In one embodiment, oxygen
concentrator 100 has a weight of less than about 20 lbs., less than
about 15 lbs., less than about 10 lbs., or less than about 5 lbs.
In an embodiment, oxygen concentrator 100 has a volume of less than
about 1000 cubic inches, less than about 750 cubic inches; less
than about 500 cubic inches, less than about 250 cubic inches, or
less than about 200 cubic inches.
[0037] Oxygen may be collected from ambient air by pressurizing
ambient air in canisters 302 and 304, which include a gas
separation adsorbent. Gas separation adsorbents useful in an oxygen
concentrator are capable of separating at least nitrogen from an
air stream to produce oxygen enriched gas. Examples of gas
separation adsorbents include molecular sieves that are capable of
separation of nitrogen from an air stream. Examples of adsorbents
that may be used in an oxygen concentrator include, but are not
limited to, zeolites (natural) or synthetic crystalline
aluminosilicates that separate nitrogen from oxygen in an air
stream under elevated pressure. Examples of synthetic crystalline
aluminosilicates that may be used include, but are not limited to:
OXYSIV adsorbents available from UOP LLC, Des Plaines, IW; SYLOBEAD
adsorbents available from W. R. Grace & Co, Columbia, Md.;
SILIPORITE adsorbents available from CECA S.A. of Paris, France;
ZEOCHEM adsorbents available from Zeochem AG, Uetikon, Switzerland;
and AgLiLSX adsorbent available from Air Products and Chemicals,
Inc., Allentown, Pa.
[0038] As shown in FIG. 1, air may enter the oxygen concentrator
through air inlet 106. Air may be drawn into air inlet 106 by
compression system 200. Compression system 200 may draw in air from
the surroundings of the oxygen concentrator and compress the air,
forcing the compressed air into one or both canisters 302 and 304.
In an embodiment, an inlet muffler 108 may be coupled to air inlet
106 to reduce sound produced by air being pulled into the oxygen
generator by compression system 200. In an embodiment, inlet
muffler 108 may be a moisture and sound absorbing muffler. For
example, a water absorbent material (such as a polymer water
absorbent material or a zeolite material) may be used to both
absorb water from the incoming air and to reduce the sound of the
air passing into the air inlet 106.
[0039] Compression system 200 may include one or more compressors
capable of compressing air. In some embodiments, compression system
may include one, two, three, four, or more compressors. Compression
system 200 as depicted that includes compressor 210 and motor 220.
Motor 220 is coupled to compressor 210 and provides an operating
force to the compressor to operate the compression mechanism.
Pressurized air, produced by compression system 200, may be forced
into one or both of the canisters 302 and 304. In some embodiments,
the ambient air may be pressurized in the canisters to a pressure
approximately in a range of 13-20 pounds per square inch (psi).
Other pressures may also be used, depending on the type of gas
separation adsorbent disposed in the canisters.
[0040] In some embodiments, motor 220 is coupled to a pressurizing
device (e.g. piston pump or a diaphragm pump). The pressuring
device may be a piston pump that has multiple pistons. During
operation, the pistons may be selectively turned on or off. In some
embodiments, motor 220 may be coupled to multiple pumps. Each pump
may be selectively turned on or off. For example, controller 400
may determine which pumps or pistons should be operated based on
predetermined operating conditions.
[0041] Coupled to each canister 302/304 are inlet valves 122/124
and outlet valves 132/134. As shown in FIG. 1, inlet valve 122 is
coupled to canister 302 and inlet valve 124 is coupled to canister
304. Outlet valve 132 is coupled to canister 302 and outlet valve
134 is coupled to canister 304. Inlet valves 122/124 are used to
control the passage of air from compression system 200 to the
respective canisters. Outlet valves 132/134 are used to release gas
from the respective canisters during a venting process. In some
embodiments, inlet valves 122/124 and outlet valves 132/134 may be
silicon plunger solenoid valves. Other types of valves, however,
may be used. Plunger valves offer advantages over other kinds of
valves by being quiet and having low slippage.
[0042] In some embodiments, a two-step valve actuation voltage may
be used to control inlet valves 122/124 and outlet valves 132/134.
For example, a high voltage (e.g., 24 V) may be applied to an inlet
valve to open the inlet valve. The voltage may then be reduced
(e.g., to 7 V) to keep the inlet valve open. Using less voltage to
keep a valve open may use less power (Power=Voltage*Current). This
reduction in voltage minimizes heat buildup and power consumption
to extend run time from the battery. When the power is cut off to
the valve, it closes by spring action. In some embodiments, the
voltage may be applied as a function of time that is not
necessarily a stepped response (e.g., a curved downward voltage
between an initial 24 V and a final 7 V).
[0043] In some embodiments, air may be pulled into the oxygen
concentrator through compressors 305, 310. In some embodiments, air
may flow from compressors 305, 310 to canisters 302, 304. In some
embodiments, one of valves 122 or 124 may be closed (e.g., as
signaled by controller 400) resulting in the combined output of
both compressors 305, 310 lowing through the other respective valve
122 or 124 into a respective canister 302, 304. For example, if
valve 124 is closed, the air from both compressors 305, 310 may
flow through valve 122. If valve 122 is closed, the air from both
compressors 305, 310 may flow through valve 124. In some
embodiments, valve 122 and valve 124 may alternate to alternately
direct the air from the compressors 305, 310 into respective
canisters 302 or 304.
[0044] In an embodiment, pressurized air is sent into one of
canisters 302 or 304 while the other canister is being vented. For
example, during use, inlet valve 122 is opened while inlet valve
124 is closed. Pressurized air from compression system 200 is
forced into canister 302, while being inhibited from entering
canister 304 by inlet valve 124. In an embodiment, a controller 400
is electrically coupled to valves 122, 124, 132, and 134.
Controller 400 includes one or more processors 410 operable to
execute program instructions stored in memory 420. The program
instructions are operable to perform various predefined methods
that are used to operate the oxygen concentrator. Controller 400
may include program instructions for operating inlet valves 122 and
124 out of phase with each other, i.e., when one of inlet valves
122 or 124 is opened, the other valve is closed. During
pressurization of canister 302, outlet valve 132 is closed and
outlet valve 134 is opened. Similar to the inlet valves, outlet
valves 132 and 134 are operated out of phase with each other. In
some embodiments, the voltages and the duration of the voltages
used to open the input and output valves may be controlled by
controller 400.
[0045] Check valves 142 and 144 are coupled to canisters 302 and
304, respectively. Check valves 142 and 144 are one way valves that
are passively operated by the pressure differentials that occur as
the canisters are pressurized and vented. Check valves 142 and 144
are coupled to canisters to allow oxygen produced during
pressurization of the canister to flow out of the canister, and to
inhibit back flow of oxygen or any other gases into the canister.
In this manner, check valves 142 and 144 act as one way valves
allowing oxygen enriched gas to exit the respective canister during
pressurization.
[0046] The term "check valve", as used herein, refers to a valve
that allows flow of a fluid (gas or liquid) in one direction and
inhibits back flow of the fluid. Examples of check valves that are
suitable for use include, but are not limited to: a ball check
valve; a diaphragm check valve; a butterfly check valve; a swing
check valve; a duckbill valve; and a lift check valve. Under
pressure, nitrogen molecules in the pressurized ambient air are
adsorbed by the gas separation adsorbent in the pressurized
canister. As the pressure increases, more nitrogen is adsorbed
until the gas in the canister is enriched in oxygen. The
non-adsorbed gas molecules (mainly oxygen) flow out of the
pressurized canister when the pressure reaches a point sufficient
to overcome the resistance of the check valve coupled to the
canister. In one embodiment, the pressure drop of the check valve
in the forward direction is less than 1 psi. The break pressure in
the reverse direction is greater than 100 psi. It should be
understood, however, that modification of one or more components
would alter the operating parameters of these valves. If the
forward flow pressure is increased, there is, generally, a
reduction in oxygen enriched gas production. If the break pressure
for reverse flow is reduced or set too low, there is, generally, a
reduction in oxygen enriched gas pressure.
[0047] In an exemplary embodiment, canister 302 is pressurized by
compressed air produced in compression system 200 and passed into
canister 302. During pressurization of canister 302 inlet valve 122
is open, outlet valve 132 is closed, inlet valve 124 is closed and
outlet valve 134 is open. Outlet valve 134 is opened when outlet
valve 132 is closed to allow substantially simultaneous venting of
canister 304 while canister 302 is pressurized. Canister 302 is
pressurized until the pressure in canister is sufficient to open
check valve 142. Oxygen enriched gas produced in canister 302 exits
through check valve and, in one embodiment, is collected in
accumulator 106.
[0048] After some time the gas separation adsorbent will become
saturated with nitrogen and will be unable to separate significant
amounts of nitrogen from incoming air. This point is usually
reached after a predetermined time of oxygen enriched gas
production. In the embodiment described above, when the gas
separation adsorbent in canister 302 reaches this saturation point,
the inflow of compressed air is stopped and canister 302 is vented
to remove nitrogen. During venting, inlet valve 122 is closed, and
outlet valve 132 is opened. While canister 302 is being vented,
canister 304 is pressurized to produce oxygen enriched gas in the
same manner described above. Pressurization of canister 304 is
achieved by closing outlet valve 134 and opening inlet valve 124.
The oxygen enriched gas exits canister 304 through check valve
144.
[0049] During venting of canister 302, outlet valve 132 is opened
allowing pressurized gas (mainly nitrogen) to exit the canister
through concentrator outlet 130. In an embodiment, the vented gases
may be directed through muffler 133 to reduce the noise produced by
releasing the pressurized gas from the canister. As gas is released
from canister 302, pressure in the canister drops. The drop in
pressure may allow the nitrogen to become desorbed from the gas
separation adsorbent. The released nitrogen exits the canister
through outlet 130, resetting the canister to a state that allows
renewed separation of oxygen from an air stream. Muffler 133 may
include open cell foam (or another material) to muffle the sound of
the gas leaving the oxygen concentrator. In some embodiments, the
combined muffling components/techniques for the input of air and
the output of gas may provide for oxygen concentrator operation at
a sound level below 50 decibels.
[0050] During venting of the canisters, it is advantageous that at
least a majority of the nitrogen is removed. In an embodiment, at
least about 50%, at least about 60%, at least about 70%, at least
about 80%, at least about 90%, at least about 95%, at least about
98%, or substantially all of the nitrogen in a canister is removed
before the canister is re-used to separate oxygen from air. In some
embodiments, a canister may be further purged of nitrogen using an
oxygen enriched stream that is introduced into the canister from
the other canister.
[0051] In an exemplary embodiment, a portion of the oxygen enriched
gas may be transferred from canister 302 to canister 304 when
canister 304 is being vented of nitrogen. Transfer of oxygen
enriched gas from canister 302 to 304, during venting of canister
304, helps to further purge nitrogen (and other gases) from the
canister. In an embodiment, oxygen enriched gas may travel through
flow restrictors 151, 153, and 155 between the two canisters. Flow
restrictor 151 may be a trickle flow restrictor. Flow restrictor
151, for example, may be a 0.009D flow restrictor (e.g., the flow
restrictor has a radius of 0.009 inches which is less than the
diameter of the tube it is inside). Flow restrictors 153 and 155
may be 0.013D flow restrictors. Other flow restrictor types and
sizes are also contemplated and may be used depending on the
specific configuration and tubing used to couple the canisters. In
some embodiments, the flow restrictors may be press fit flow
restrictors that restrict air flow by introducing a narrower
diameter in their respective tube. In some embodiments, the press
fit flow restrictors may be made of sapphire, metal or plastic
(other materials are also contemplated).
[0052] Flow of oxygen enriched gas is also controlled by use of
valve 152 and valve 154. Valves 152 and 154 may be opened for a
short duration during the venting process (and may be closed
otherwise) to prevent excessive oxygen loss out of the purging
canister. Other durations are also contemplated. In an exemplary
embodiment, canister 302 is being vented and it is desirable to
purge canister 302 by passing a portion of the oxygen enriched gas
being produced in canister 304 into canister 302. A portion of
oxygen enriched gas, upon pressurization of canister 304, will pass
through flow restrictor 151 into canister 302 during venting of
canister 302. Additional oxygen enriched air is passed into
canister 302, from canister 304, through valve 154 and flow
restrictor 155. Valve 152 may remain closed during the transfer
process, or may be opened if additional oxygen enriched gas is
needed. The selection of appropriate flow restrictors 151 and 155,
coupled with controlled opening of valve 154 allows a controlled
amount of oxygen enriched gas to be sent from canister 304 to 302.
In an embodiment, the controlled amount of oxygen enriched gas is
an amount sufficient to purge canister 302 and minimize the loss of
oxygen enriched gas through venting valve 132 of canister 302.
While this embodiment describes venting of canister 302, it should
be understood that the same process can be used to vent canister
304 using flow restrictor 151, valve 152 and flow restrictor
153.
[0053] The pair of equalization/vent valves 152/154 work with flow
restrictors 153 and 155 to optimize the air flow balance between
the two canisters. This may allow for better flow control for
venting the canisters with oxygen enriched gas from the other of
the canisters. It may also provide better flow direction between
the two canisters. It has been found that, while flow valves
152/154 may be operated as bi-directional valves, the flow rate
through such valves varies depending on the direction of fluid
flowing through the valve. For example, oxygen enriched gas flowing
from canister 304 toward canister 302 has a flow rate faster
through valve 152 than the flow rate of oxygen enriched gas flowing
from canister 302 toward canister 304 through valve 152. If a
single valve was to be used, eventually either too much or too
little oxygen enriched gas would be sent between the canisters and
the canisters would, over time, begin to produce different amounts
of oxygen enriched gas. Use of opposing valves and flow restrictors
on parallel air pathways may equalize the flow pattern of the
oxygen between the two canisters. Equalizing the flow may allow for
a steady amount of oxygen available to the user over multiple
cycles and also may allow a predictable volume of oxygen to purge
the other of the canisters. In some embodiments, the air pathway
may not have restrictors but may instead have a valve with a built
in resistance or the air pathway itself may have a narrow radius to
provide resistance.
[0054] At times, oxygen concentrator may be shut down for a period
of time. When an oxygen concentrator is shut down, the temperature
inside the canisters may drop as a result of the loss of adiabatic
heat from the compression system. As the temperature drops, the
volume occupied by the gases inside the canisters will drop.
Cooling of the canisters may lead to a negative pressure in the
canisters. Valves (e.g., valves 122, 124, 132, and 134) leading to
and from the canisters are dynamically sealed rather than
hermetically sealed. Thus, outside air may enter the canisters
after shutdown to accommodate the pressure differential. When
outside air enters the canisters, moisture from the outside air may
condense inside the canister as the air cools. Condensation of
water inside the canisters may lead to gradual degradation of the
gas separation adsorbents, steadily reducing ability of the gas
separation adsorbents to produce oxygen enriched gas.
[0055] In an embodiment, outside air may be inhibited from entering
canisters after the oxygen concentrator is shut down by
pressurizing both canisters prior to shut down. By storing the
canisters under a positive pressure, the valves may be forced into
a hermetically closed position by the internal pressure of the air
in the canisters. In an embodiment, the pressure in the canisters,
at shutdown, should be at least greater than ambient pressure. As
used herein the term "ambient pressure" refers to the pressure of
the surroundings that the oxygen generator is located (e.g. the
pressure inside a room, outside, in a plane, etc.). In an
embodiment, the pressure in the canisters, at shutdown, is at least
greater than standard atmospheric pressure (i.e., greater than 760
mmHg (Torr), 1 atm, 101,325 Pa). In an embodiment, the pressure in
the canisters, at shutdown, is at least about 1.1 times greater
than ambient pressure; is at least about 1.5 times greater than
ambient pressure; or is at least about 2 times greater than ambient
pressure.
[0056] In an embodiment, pressurization of the canisters may be
achieved by directing pressurized air into each canister from the
compression system and closing all valves to trap the pressurized
air in the canisters. In an exemplary embodiment, when a shutdown
sequence is initiated, inlet valves 122 and 124 are opened and
outlet valves 132 and 134 are closed. Because inlet valves 122 and
124 are joined together by a common conduit, both canisters 302 and
304 may become pressurized as air and or oxygen enriched gas from
one canister may be transferred to the other canister. This
situation may occur when the pathway between the compression system
and the two inlet valves allows such transfer. Because the oxygen
generator operates in an alternating pressurize/venting mode, at
least one of the canisters should be in a pressurized state at any
given time. In an alternate embodiment, the pressure may be
increased in each canister by operation of compression system 200.
When inlet valves 122 and 124 are opened, pressure between
canisters 302 and 304 will equalize, however, the equalized
pressure in either canister may not be sufficient to inhibit air
from entering the canisters during shutdown. In order to ensure
that air is inhibited from entering the canisters, compression
system 200 may be operated for a time sufficient to increase the
pressure inside both canisters to a level at least greater than
ambient pressure. Regardless of the method of pressurization of the
canisters, once the canisters are pressurized, inlet valves 122 and
124 are closed, trapping the pressurized air inside the canisters,
which inhibits air from entering the canisters during the shutdown
period.
[0057] An outlet system, coupled to one or more of the canisters,
includes one or more conduits for providing oxygen enriched gas to
a user. In an embodiment, oxygen enriched gas produced in either of
canisters 302 and 304 is collected in accumulator 106 through check
valves 142 and 144, respectively, as depicted schematically in FIG.
1. The oxygen enriched gas leaving the canisters may be collected
in oxygen accumulator 106 prior to being provided to a user. In
some embodiments, a tube may be coupled to accumulator 106 to
provide the oxygen enriched gas to the user. Oxygen enriched gas
may be provided to the user through an airway delivery device that
transfer the oxygen enriched gas to the user's mouth and/or nose.
In an embodiment, an outlet may include a tube that directs the
oxygen toward a user's nose and/or mouth that may not be directly
coupled to the user's nose.
[0058] Turning to FIG. 2, a schematic diagram of an embodiment of
an outlet system for an oxygen concentrator is shown. Supply valve
160 may be coupled to outlet tube to control the release of the
oxygen enriched gas from accumulator 106 to the user. In an
embodiment, supply valve 160 is an electromagnetically actuated
plunger valve. Supply valve 160 is actuated by controller 400 to
control the delivery of oxygen enriched gas to a user. Actuation of
supply valve 160 is not timed or synchronized to the pressure swing
adsorption process. Instead, actuation is, in some embodiments,
synchronized to the patient's breathing. Additionally, supply valve
160 may have multiple actuations to help establish a clinically
effective flow profile for providing oxygen enriched gas.
[0059] Oxygen enriched gas in accumulator 106 passes through supply
valve 160 into expansion chamber 170 as depicted in FIG. 2. In an
embodiment, expansion chamber may include one or more devices
capable of being used to determine an oxygen concentration of gas
passing through the chamber. Oxygen enriched gas in expansion
chamber 170 builds briefly, through release of gas from accumulator
by supply valve 160, and then is bled through small orifice flow
restrictor 175 to flow rate sensor 185 and then to particulate
filter 187. Flow restrictor 175 may be a 0.025 D flow restrictor.
Other flow restrictor types and sizes may be used. In some
embodiments, the diameter of the air pathway in the housing may be
restricted to create restricted air flow. Flow rate sensor 185 may
be any sensor capable of assessing the rate of gas flowing through
the conduit. Particulate filter 187 may be used to filter bacteria,
dust, granule particles, etc. prior to delivery of the oxygen
enriched gas to the user. The oxygen enriched gas passes through
filter 187 to connector 190 which sends the oxygen enriched gas to
the user via conduit 192 and to pressure sensor 194.
[0060] The fluid dynamics of the outlet pathway, coupled with the
programmed actuations of supply valve 160, results in a bolus of
oxygen being provided at the correct time and with a flow profile
that assures rapid delivery into the patient's lungs without any
excessive flow rates that would result in wasted retrograde flow
out the nostrils and into the atmosphere. It has been found, in our
specific system, that the total volume of the bolus required for
prescriptions is equal to 11 mL for each LPM, i.e., 11 mL for a
prescription of 1 LPM; 22 mL for a prescription of 2 LPM; 33 mL for
a prescription of 3 LPM; 44 mL for a prescription of 4 LPM; 55 mL
for a prescription of 5 LPM; etc. This is generally referred to as
the LPM equivalent. It should be understood that the LPM equivalent
may vary between apparatus due to differences in construction
design, tubing size, chamber size, etc.
[0061] Expansion chamber 170 may include one or more oxygen sensors
capable of being used to determine an oxygen concentration of gas
passing through the chamber. In an embodiment, the oxygen
concentration of gas passing through expansion chamber 170 is
assessed using oxygen sensor 165. An oxygen sensor is a device
capable of detecting oxygen in a gas. Examples of oxygen sensors
include, but are not limited to, ultrasonic oxygen sensors,
electrical oxygen sensors, and optical oxygen sensors. In one
embodiment, oxygen sensor 165 is an ultrasonic oxygen sensor that
includes ultrasonic emitter 166 and ultrasonic receiver 168. In
some embodiments, ultrasonic emitter 166 may include multiple
ultrasonic emitters and ultrasonic receiver 168 may include
multiple ultrasonic receivers. In embodiments having multiple
emitters/receivers, the multiple ultrasonic emitters and multiple
ultrasonic receivers may be axially aligned (e.g., across the gas
mixture flow path which may be perpendicular to the axial
alignment).
[0062] In use, an ultrasonic sound wave (from emitter 166) may be
directed through oxygen enriched gas disposed in chamber 170 to
receiver 168. Ultrasonic sensor assembly may be based on detecting
the speed of sound through the gas mixture to determine the
composition of the gas mixture (e.g., the speed of sound is
different in nitrogen and oxygen). In a mixture of the two gases,
the speed of sound through the mixture may be an intermediate value
proportional to the relative amounts of each gas in the mixture. In
use, the sound at the receiver 168 is slightly out of phase with
the sound sent from emitter 166. This phase shift is due to the
relatively slow velocity of sound through a gas medium as compared
with the relatively fast speed of the electronic pulse through
wire. The phase shift, then, is proportional to the distance
between the emitter and the receiver and the speed of sound through
the expansion chamber. The density of the gas in the chamber
affects the speed of sound through the chamber and the density is
proportional to the ratio of oxygen to nitrogen in the chamber.
Therefore, the phase shift can be used to measure the concentration
of oxygen in the expansion chamber. In this manner the relative
concentration of oxygen in the accumulation chamber may be assessed
as a function of one or more properties of a detected sound wave
traveling through the accumulation chamber.
[0063] In some embodiments, multiple emitters 166 and receivers 168
may be used. The readings from the emitters 166 and receivers 168
may be averaged to cancel errors that may be inherent in turbulent
flow systems. In some embodiments, the presence of other gases may
also be detected by measuring the transit time and comparing the
measured transit time to predetermined transit times for other
gases and/or mixtures of gases.
[0064] The sensitivity of the ultrasonic sensor system may be
increased by increasing the distance between emitter 166 and
receiver 168, for example to allow several sound wave cycles to
occur between emitter 166 and the receiver 168. In some
embodiments, if at least two sound cycles are present, the
influence of structural changes of the transducer may be reduced by
measuring the phase shift relative to a fixed reference at two
points in time. If the earlier phase shift is subtracted from the
later phase shift, the shift caused by thermal expansion of
expansion chamber 170 may be reduced or cancelled. The shift caused
by a change of the distance between emitter 166 and receiver 168
may be the approximately the same at the measuring intervals,
whereas a change owing to a change in oxygen concentration may be
cumulative. In some embodiments, the shift measured at a later time
may be multiplied by the number of intervening cycles and compared
to the shift between two adjacent cycles. Further details regarding
sensing of oxygen in the expansion chamber may be found, for
example, in U.S. Published Patent Application No. 2009-0065007,
published Mar. 12, 2009, and entitled "Oxygen Concentrator
Apparatus and Method, which is incorporated herein by
reference.
[0065] Flow rate sensor 185 may be used to determine the flow rate
of gas flowing through the outlet system. Flow rate sensors that
may be used include, but are not limited to: diaphragm/bellows flow
meters; rotary flow meters (e.g. Hall Effect flow meters); turbine
flow meters; orifice flow meters; and ultrasonic flow meters. Flow
rate sensor 185 may be coupled to controller 400. The rate of gas
flowing through the outlet system may be an indication of the
breathing volume of the user. Changes in the flow rate of gas
flowing through the outlet system may also be used to determine a
breathing rate of the user. Controller 400 may control actuation of
supply valve 160 based on the breathing rate and/or breathing
volume of the user, as assessed by flow rate sensor 185
[0066] In some embodiments, ultrasonic sensor system 165 and, for
example, flow rate sensor 185 may provide a measurement of an
actual amount of oxygen being provided. For example, follow rate
sensor 185 may measure a volume of gas (based on flow rate)
provided and ultrasonic sensor system 165 may provide the
concentration of oxygen of the gas provided. These two measurements
together may be used by controller 400 to determine an
approximation of the actual amount of oxygen provided to the
user.
[0067] Oxygen enriched gas passes through flow meter 185 to filter
187. Filter 187 removes bacteria, dust, granule particles, etc.
prior to providing the oxygen enriched gas to the user. The
filtered oxygen enriched gas passes through filter 187 to connector
190. Connector 190 may be a "Y" connector coupling the outlet of
filter 187 to pressure sensor 194 and outlet conduit 192. Pressure
sensor 194 may be used to monitor the pressure of the gas passing
through conduit 192 to the user. Changes in pressure, sensed by
pressure sensor 194, may be used to determine a breathing rate of a
user, as well as the onset of inhalation. Controller 400 may
control actuation of supply valve 160 based on the breathing rate
and/or onset of inhalation of the user, as assessed by pressure
sensor 194. In an embodiment, controller 400 may control actuation
of supply valve 160 based on information provided by flow rate
sensor 185 and pressure sensor 194.
[0068] Oxygen enriched gas may be provided to a user through
conduit 192. In an embodiment, conduit 192 may be a silicone tube.
Conduit 192 may be coupled to a user using an airway coupling
member 196, as depicted in FIG. 3. Airway coupling member 196 may
be any device capable of providing the oxygen enriched gas to nasal
cavities or oral cavities. Examples of airway coupling members
include, but are not limited to: nasal masks, nasal pillows, nasal
prongs, nasal cannulas, and mouthpieces. A nasal cannula airway
delivery device is depicted in FIG. 3. During use, oxygen enriched
gas from oxygen concentrator system 100 is provided to the user
through conduit 192 and airway coupling member 196. Airway coupling
member 196 is positioned proximate to a user's airway (e.g.,
proximate to the user's mouth and or nose) to allow delivery of the
oxygen enriched gas to the user while allowing the user to breath
air from the surroundings.
Canister System
[0069] Oxygen concentrator system 100 may include at least two
canisters, each canister including a gas separation adsorbent. The
canisters of oxygen concentrator system 100 may be disposed formed
from a molded housing. In an embodiment, canister system 300
includes two housing components 310 and 510, as depicted in FIG. 4.
The housing components 310 and 510 may be formed separately and
then coupled together. In some embodiments, housing components 310
and 510 may be injection molded or compression molded. Housing
components 310 and 510 may be made from a thermoplastic polymer
such as polycarbonate, methylene carbide, polystyrene,
acrylonitrile butadiene styrene (ABS), polypropylene, polyethylene,
or polyvinyl chloride. In another embodiment, housing components
310 and 510 may be made of a thermoset plastic or metal (such as
stainless steel or a light-weight aluminum alloy). Lightweight
materials may be used to reduce the weight of the oxygen
concentrator 100. In some embodiments, the two housings 310 and 510
may be fastened together using screws or bolts. Alternatively,
housing components 310 and 510 may be solvent welded together.
[0070] As shown, valve seats 320, 322, 324, and 326 and air
pathways 330 and 332 may be integrated into the housing component
310 to reduce the number of sealed connections needed throughout
the air flow of the oxygen concentrator 100. In various
embodiments, the housing components 310 and 410 of the oxygen
concentrator 100 may form a two-part molded plastic frame that
defines two canisters 302 and 304 and accumulation chamber 106.
[0071] Air pathways/tubing between different sections in housing
components 310 and 510 may take the form of molded conduits.
Conduits in the form of molded channels for air pathways may occupy
multiple planes in housing components 310 and 510. For example, the
molded air conduits may be formed at different depths and at
different x,y,z positions in housing components 310 and 510. In
some embodiments, a majority or substantially all of the conduits
may be integrated into the housing components 310 and 510 to reduce
potential leak points.
[0072] In some embodiments, prior to coupling housing components
310 and 510 together, O-rings may be placed between various points
of housing components 310 and 510 to ensure that the housing
components are properly sealed. In some embodiments, components may
be integrated and/or coupled separately to housing components 310
and 510. For example, tubing, flow restrictors (e.g., press fit
flow restrictors), oxygen sensors, gas separation adsorbents 139,
check valves, plugs, processors, power supplies, etc. may be
coupled to housing components 510 and 410 before and/or after the
housing components are coupled together.
[0073] In some embodiments, apertures 337 leading to the exterior
of housing components 310 and 410 may be used to insert devices
such as flow restrictors. Apertures may also be used for increased
moldability. One or more of the apertures may be plugged after
molding (e.g., with a plastic plug). In some embodiments, flow
restrictors may be inserted into passages prior to inserting plug
to seal the passage. Press fit flow restrictors may have diameters
that may allow a friction fit between the press fit flow
restrictors and their respective apertures. In some embodiments, an
adhesive may be added to the exterior of the press fit flow
restrictors to hold the press fit flow restrictors in place once
inserted. In some embodiments, the plugs may have a friction fit
with their respective tubes (or may have an adhesive applied to
their outer surface). The press fit flow restrictors and/or other
components may be inserted and pressed into their respective
apertures using a narrow tip tool or rod (e.g., with a diameter
less than the diameter of the respective aperture). In some
embodiments, the press fit flow restrictors may be inserted into
their respective tubes until they abut a feature in the tube to
halt their insertion. For example, the feature may include a
reduction in radius. Other features are also contemplated (e.g., a
bump in the side of the tubing, threads, etc.). In some
embodiments, press fit flow restrictors may be molded into the
housing components (e.g., as narrow tube segments).
[0074] In some embodiments, spring baffle 129 may be placed into
respective canister receiving portions of housing component 310 and
510 with the spring side of the baffle 129 facing the exit of the
canister. Spring baffle 129 may apply force to gas separation
adsorbent 139 in the canister while also assisting in preventing
gas separation adsorbent 139 from entering the exit apertures. Use
of a spring baffle 129 may keep the gas separation adsorbent
compact while also allowing for expansion (e.g., thermal
expansion). Keeping the gas separation adsorbent 139 compact may
prevent the gas separation adsorbent from breaking during movement
of the oxygen concentrator system 100).
[0075] In some embodiments, pressurized air from the compression
system 200 may enter air inlet 306. Air inlet 306 is coupled to
inlet conduit 330. Air enters housing component 310 through inlet
306 travels through conduit 330, and then to valve seats 322 and
324. FIG. 5 and FIG. 6 depict an end view of housing 310. FIG. 5
depicts an end view of housing 310 prior to fitting valves to
housing 310. FIG. 6 depicts an end view of housing 310 with the
valves fitted to the housing 310. Valve seats 322 and 324 are
configured to receive inlet valves 122 and 124 respectively. Inlet
valve 122 is coupled to canister 302 and inlet valve 124 is coupled
to canister 304. Housing 310 also includes valve seats 332 and 334
configured to receive outlet valves 132 and 134 respectively.
Outlet valve 132 is coupled to canister 302 and outlet valve 134 is
coupled to canister 304. Inlet valves 122/124 are used to control
the passage of air from conduit 330 to the respective
canisters.
[0076] In an embodiment, pressurized air is sent into one of
canisters 302 or 304 while the other canister is being vented. For
example, during use, inlet valve 122 is opened while inlet valve
124 is closed. Pressurized air from compression system 200 is
forced into canister 302, while being inhibited from entering
canister 304 by inlet valve 124. During pressurization of canister
302, outlet valve 132 is closed and outlet valve 134 is opened.
Similar to the inlet valves, outlet valves 132 and 134 are operated
out of phase with each other. Each inlet valve seat 322 includes an
opening 375 that passes through housing 310 into canister 302.
Similarly valve seat 324 includes an opening 325 that passes
through housing 310 into canister 302. Air from conduit 330 passes
through openings 323, or 325 if the respective valve (322 or 324)
is open, and enters a canister.
[0077] Check valves 142 and 144 (See, FIG. 4) are coupled to
canisters 302 and 304, respectively. Check valves 142 and 144 are
one way valves that are passively operated by the pressure
differentials that occur as the canisters are pressurized and
vented. Oxygen enriched gas, produced in canisters 302 and 304 pass
from the canister into openings 542 and 544 of housing 410. A
passage (not shown) links openings 542 and 544 to conduits 342 and
344, respectively. Oxygen enriched gas produced in canister 302
passes from the canister though opening 542 and into conduit 342
when the pressure in the canister is sufficient to open check valve
142. When check valve 142 is open, oxygen enriched gas flows
through conduit 342 toward the end of housing 310. Similarly,
oxygen enriched gas produced in canister 304 passes from the
canister though opening 544 and into conduit 344 when the pressure
in the canister is sufficient to open check valve 144. When check
valve 144 is open, oxygen enriched gas flows through conduit 344
toward the end of housing 310.
[0078] Oxygen enriched gas from either canister, travels through
conduit 342 or 344 and enters conduit 346 formed in housing 310.
Conduit 346 includes openings that couple the conduit to conduit
342, conduit 344 and accumulator 106. Thus oxygen enriched gas,
produced in canister 302 or 304, travels to conduit 346 and passes
into accumulator 106.
[0079] After some time the gas separation adsorbent will become
saturated with nitrogen and will be unable to separate significant
amounts of nitrogen from incoming air. When the gas separation
adsorbent in a canister reaches this saturation point, the inflow
of compressed air is stopped and the canister is vented to remove
nitrogen. Canister 302 is vented by closing inlet valve 122 and
opening outlet valve 132. Outlet valve 132 releases the vented gas
from canister 302 into the volume defined by the end of housing
310. Foam material may cover the end of housing 310 to reduce the
sound made by release of gases from the canisters. Similarly,
canister 304 is vented by closing inlet valve 124 and opening
outlet valve 134. Outlet valve 134 releases the vented gas from
canister 304 into the volume defined by the end of housing 310.
[0080] While canister 302 is being vented, canister 304 is
pressurized to produce oxygen enriched gas in the same manner
described above. Pressurization of canister 304 is achieved by
closing outlet valve 134 and opening inlet valve 124. The oxygen
enriched gas exits canister 304 through check valve 144.
[0081] In an exemplary embodiment, a portion of the oxygen enriched
gas may be transferred from canister 302 to canister 304 when
canister 304 is being vented of nitrogen. Transfer of oxygen
enriched gas from canister 302 to canister 304, during venting of
canister 304, helps to further purge nitrogen (and other gases)
from the canister. Flow of oxygen enriched gas between the
canisters is controlled using flow restrictors and valves, as
depicted in FIG. 1. Three conduits are formed in housing 510 for
use in transferring oxygen enriched gas between canisters. As shown
in FIG. 7, conduit 530 couples canister 302 to canister 304. Flow
restrictor 151 (not shown) is disposed in conduit 530, between
canister 302 and canister 304 to restrict flow of oxygen enriched
gas during use. Conduit 532 also couples canister 302 to 304.
Conduit 532 is coupled to valve seat 552 which receives valve 152,
as shown in FIG. 8. Flow restrictor 153 (not shown) is disposed in
conduit 532, between canister 302 and 304. Conduit 534 also couples
canister 302 to 304. Conduit 534 is coupled to valve seat 554 which
receives valve 154, as shown in FIG. 8. Flow restrictor 155 (not
shown) is disposed in conduit 434, between canister 302 and 304.
The pair of equalization/vent valves 152/154 work with flow
restrictors 153 and 155 to optimize the air flow balance between
the two canisters.
[0082] Oxygen enriched gas in accumulator 106 passes through supply
valve 160 into expansion chamber 170 which is formed in housing
510. An opening (not shown) in housing 510 couples accumulator 106
to supply valve 160. In an embodiment, expansion chamber may
include one or more devices capable of being used to determine an
oxygen concentration of gas passing through the chamber.
Controller System
[0083] Operation of oxygen concentrator system 100 may be performed
automatically using an internal controller 400 coupled to various
components of the oxygen concentrator system, as described herein.
Controller 400 includes one or more processors 410 and internal
memory 420, as depicted in FIG. 1. Methods used to operate and
monitor oxygen concentrator system 100 may be implemented by
program instructions stored in memory 420 or a carrier medium
coupled to controller 400, and executed by one or more processors
410. A non-transitory memory medium may include any of various
types of memory devices or storage devices. The term "memory
medium" is intended to include an installation medium, e.g., a
Compact Disc Read Only Memory (CD-ROM), floppy disks, or tape
device; a computer system memory or random access memory such as
Dynamic Random Access Memory (DRAM), Double Data Rate Random Access
Memory (DDR RAM), Static Random Access Memory (SRAM), Extended Data
Out Random Access Memory (EDO RAM), Rambus Random Access Memory
(RAM), etc.; or a non-volatile memory such as a magnetic media,
e.g., a hard drive, or optical storage. The memory medium may
comprise other types of memory as well, or combinations thereof. In
addition, the memory medium may be located in a first computer in
which the programs are executed, or may be located in a second
different computer that connects to the first computer over a
network, such as the Internet. In the latter instance, the second
computer may provide program instructions to the first computer for
execution. The term "memory medium" may include two or more memory
mediums that may reside in different locations, e.g., in different
computers that are connected over a network.
[0084] In some embodiments, controller 400 includes processor 410
that includes, for example, one or more field programmable gate
arrays (FPGAs), microcontrollers, etc. included on a circuit board
disposed in oxygen concentrator system 100. Processor 410 is
capable of executing programming instructions stored in memory 420.
In some embodiments, programming instructions may be built into
processor 410 such that a memory external to the processor may not
be separately accessed (i.e., the memory 420 may be internal to the
processor 410).
[0085] Processor 410 may be coupled to various components of oxygen
concentrator system 100, including, but not limited to compression
system 200, one or more of the valves used to control fluid flow
through the system (e.g., valves 122, 124, 132, 134, 152, 154, 160,
or combinations thereof), oxygen sensor 165, pressure sensor 194,
flow rate monitor 180, temperature sensors, fans, and any other
component that may be electrically controlled. In some embodiments,
a separate processor (and/or memory) may be coupled to one or more
of the components.
[0086] Controller 400 is programmed to operate oxygen concentrator
system 100 and is further programmed to monitor the oxygen
concentrator system for malfunction states. For example, in one
embodiment, controller 400 is programmed to trigger an alarm if the
system is operating and no breathing is detected by the user for a
predetermined amount of time. For example, if controller 400 does
not detect a breath for a period of 75 seconds, an alarm LED may be
lit and/or an audible alarm may be sounded. If the user has truly
stopped breathing, for example, during a sleep apnea episode, the
alarm may be sufficient to awaken the user, causing the user to
resume breathing. The action of breathing may be sufficient for
controller 400 to reset this alarm function. Alternatively, if the
system is accidently left on when output conduit 192 is removed
from the user, the alarm may serve as a reminder for the user to
turn oxygen concentrator system 100 off.
[0087] Controller 400 is further coupled to oxygen sensor 165, and
may be programmed for continuous or periodic monitoring of the
oxygen concentration of the oxygen enriched gas passing through
expansion chamber 170. A minimum oxygen concentration threshold may
be programmed into controller 400, such that the controller lights
an LED visual alarm and/or an audible alarm to warn the patient of
the low concentration of oxygen.
[0088] Controller 400 is also coupled to internal power supply 180
and is capable of monitoring the level of charge of the internal
power supply. A minimum voltage and/or current threshold may be
programmed into controller 400, such that the controller lights an
LED visual alarm and/or an audible alarm to warn the patient of low
power condition. The alarms may be activated intermittently and at
an increasing frequency as the battery approaches zero usable
charge.
[0089] Further functions of controller 400 are described in detail
in other sections of this disclosure.
[0090] A user may have a low breathing rate or depth if relatively
inactive (e.g., asleep, sitting, etc.) as assessed by comparing the
detected breathing rate or depth to a threshold. The user may have
a high breathing rate or depth if relatively active (e.g., walking,
exercising, etc.). An active/sleep mode may be assessed
automatically and/or the user may manually indicate a respective
active or sleep mode by a pressing button for active mode and
another button for sleep mode. In some embodiments, a user may
toggle a switch from active mode, normal mode, or sedentary mode.
The adjustments made by the oxygen concentrator system in response
to activating active mode or sleep mode are described in more
detail herein.
Methods of Delivery of Oxygen Enriched Gas
[0091] The main use of an oxygen concentrator system is to provide
supplemental oxygen to a user. Generally, the amount of
supplemental oxygen to be provided is assessed by a physician.
Typical prescribed amounts of supplemental oxygen may range from
about 1 LPM to up to about 10 LPM. The most commonly prescribed
amounts are 1 LPM, 2 LPM, 3 LPM, and 4 LPM. Generally, oxygen
enriched gas is provided to the use during a breathing cycle to
meet the prescription requirement of the user. As used herein the
term "breathing cycle" refers to an inhalation followed by an
exhalation of a person.
[0092] In order to minimize the amount of oxygen enriched gas that
is needed to be produced to meet the prescribed amounts, controller
400 may be programmed to time delivery of the oxygen enriched gas
with the user's inhalations. Releasing the oxygen enriched gas to
the user as the user inhales may prevent unnecessary oxygen
generation (further reducing power requirements) by not releasing
oxygen, for example, when the user is exhaling. Reducing the amount
of oxygen required may effectively reduce the amount of air
compressing needed for oxygen concentrator 100 (and subsequently
may reduce the power demand from the compressors).
[0093] Oxygen enriched gas, produced by oxygen concentrator system
100 is stored in an oxygen accumulator 106 and released to the user
as the user inhales. The amount of oxygen enriched gas provided by
the oxygen concentrator system is controlled, in part, by supply
valve 160. In an embodiment, supply valve 160 is opened for a
sufficient amount of time to provide the appropriate amount of
oxygen enriched gas, as assessed by controller 400, to the user. In
order to minimize the amount of oxygen required to meet the
prescription requirements of a user, the oxygen enriched gas may be
provided in a bolus when a user's inhalation is first detected. For
example, the bolus of oxygen enriched gas may be provided in the
first few milliseconds of a user's inhalation.
[0094] In an embodiment, pressure sensor 194 and/or flow rate
sensor 185 may be used to determine the onset of inhalation by the
user. For example, the user's inhalation may be detected by using
pressure sensor 194. In use, a conduit for providing oxygen
enriched gas is coupled to a user's nose and/or mouth (e.g., using
a nasal cannula or a face mask). At the onset of an inhalation, the
user begins to draw air into their body through the nose and/or
mouth. As the air is drawn in, a negative pressure is generated at
the end of the conduit, due, in part, to the venturi action of the
air being drawn across the end of the delivery conduit. Pressure
sensor 194 may be operable to create a signal when a drop in
pressure is detected, to signal the onset of inhalation. Upon
detection of the onset of inhalation, supply valve 160 is
controlled to release a bolus of oxygen enriched gas from the
accumulator 106.
[0095] In some embodiments, pressure sensor 194 may provide a
signal that is proportional to the amount of positive or negative
pressure applied to a sensing surface. The amount of the pressure
change detected by pressure sensor 194 may be used to refine the
amount of oxygen enriched gas being provided to the user. For
example, if a large negative pressure change is detected by
pressure sensor 194, the volume of oxygen enriched gas provided to
the user may be increased to take into account the increased volume
of gas being inhaled by the user. If a smaller negative pressure is
detected, the volume of oxygen enriched gas provided to the user
may be decreased to take into account the decreased volume of gas
being inhaled by the user. A positive change in the pressure
indicates an exhalation by the user and is generally a time that
release of oxygen enriched gas is discontinued. Generally while a
positive pressure change is sensed, valve 160 remains closed until
the next onset of inhalation.
[0096] In some embodiments, the sensitivity of the pressure sensor
194 may be affected by the physical distance of the pressure sensor
194 from the user, especially if the pressure sensor is located in
oxygen concentrator system 100 and the pressure difference is
detected through the tubing coupling the oxygen concentrator system
to the user. In some embodiments, the pressure sensor may be placed
in the airway delivery device used to provide the oxygen enriched
gas to the user. A signal from the pressure sensor may be provided
to controller 400 in the oxygen concentrator 100 electronically via
a wire or through telemetry such as through BLUETOOTH.RTM.
(Bluetooth, SIG, Inc. Kirkland, Wash.) or other wireless
technology.
[0097] In an embodiment, the user's inhalation may be detected by
using flow rate sensor 185. In use, a conduit for providing oxygen
enriched gas is coupled to a user's nose and/or mouth (e.g., using
a nasal cannula or face mask). At the onset of an inhalation, the
user begins to draw air into their body through the nose and/or
mouth. As the air is drawn in, an increase in flow of gas passing
through conduit is created. Flow rate sensor 185 may be operable to
create a signal when an increase in flow rate is detected, to
signal the onset of inhalation. Upon detection of the onset of
inhalation, supply valve 160 is controlled to release a bolus of
oxygen enriched gas from the accumulator 106.
[0098] A user breathing at a rate of 30 breaths per minute (BPM)
during an active state (e.g., walking, exercising, etc.) may
consume two and one-half times as much oxygen as a user who is
breathing at 12 BPM during a sedentary state (e.g., asleep,
sitting, etc.). Pressure sensor 194 and/or flow rate sensor 185 may
be used to determine the breathing rate of the user. Controller 400
may process information received from pressure sensor 194 and/or
flow rate sensor 185 and determine a breathing rate based on the
frequency of the onset of inhalation. The detected breathing rate
of the user may be used to adjust the bolus of oxygen enriched gas.
The volume of the bolus of oxygen enriched gas may be increased as
the users breathing rate increase, and may be decreased as the
users breathing rate decreases. Controller 400 may automatically
adjust the bolus based on the detected activity state of the user.
Alternatively, the user may manually indicate a respective active
or sedentary mode by selecting the appropriate option on the
control panel of the oxygen concentrator. Alternatively, a user may
operate controller 400 from a remote electronic device. For
example, a user may operate the controller using a smart phone or
tablet device.
[0099] In some embodiments, if the user's current activity level as
assessed using the detected user's breathing rate exceeds a
predetermined threshold, controller 400 may implement an alarm
(e.g., visual and/or audio) to warn the user that the current
breathing rate is exceeding the delivery capacity of the oxygen
concentrator system. For example, the threshold may be set at 20
breaths per minute.
[0100] In some embodiments, controller 400 may operate the oxygen
concentrator based on the change in the inspiration breath pressure
threshold. The frequency and/or duration of the provided oxygen
enriched gas to the user relative to the current frequency and/or
duration may be adjusted based on the change in the inspiration
breath pressure threshold. Upon determining that the inspiration
breath pressure threshold has been lowered, the controller 400 may
switch the oxygen concentrator to a sedentary mode. Controller 400
may switch the oxygen concentrator to an active mode, when the
inspiration breath pressure threshold has been raised.
[0101] In some embodiments, as seen in FIG. 9, the bolus of
provided oxygen enriched gas may include two or more pulses. For
example, with a one liter per minute (LPM) delivery rate, the bolus
may include two pulses: a first pulse 556 at approximately 7 cubic
centimeters and a second pulse 558 at approximately 3 cubic
centimeters. Other delivery rates, pulse sizes, and number of
pulses are also contemplated. For example, at 2 LPMs, the first
pulse may be approximately 14 cubic centimeters and a second pulse
may be approximately 6 cubic centimeters and at 3 LPMs, the first
pulse may be approximately 21 cubic centimeters and a second pulse
may be approximately 9 cubic centimeters. In some embodiments, the
larger pulse 556 may be provided when the onset of inhalation is
detected (e.g., detected by pressure sensor 194). In some
embodiments, the pulses may be provided when the onset of
inhalation is detected and/or may be spread time-wise evenly
through the breath. In some embodiments, the pulses may be
stair-stepped through the duration of the breath. In some
embodiments, the pulses may be distributed in a different pattern.
Additional pulses may also be used (e.g., 3, 4, 5, etc. pulses per
breath). While the first pulse 556 is shown to be approximately
twice the second pulse 558, in some embodiments, the second pulse
558 may be larger than the first pulse 556. In some embodiments,
pulse size and length may be controlled by, for example, supply
valve 160 which may open and close in a timed sequence to provide
the pulses. A bolus with multiple pulses may have a smaller impact
on a user than a bolus with a single pulse. The multiple pulses may
also result in less drying of a user's nasal passages and less
blood oxygen desaturation. The multiple pulses may also result in
less oxygen waste.
[0102] In some embodiments, the sensitivity of the oxygen
concentrator 100 may be selectively attenuated to reduce false
inhalation detections due to movement of air from a different
source (e.g., movement of ambient air). For example, the oxygen
concentrator 100 may have two selectable modes--an active mode and
an inactive mode. In some embodiments, the user may manually select
a mode (e.g., through a switch or user interface). In some
embodiments, the mode may be automatically selected by the oxygen
concentrator 100 based on a detected breathing rate. For example,
the oxygen concentrator 100 may use the pressure sensor 194 to
detect a breathing rate of the user. If the breathing rate is above
a threshold, the oxygen concentrator 100 may operate in an active
mode (otherwise, the oxygen concentrator may operate in an inactive
mode). Other modes and thresholds are also contemplated.
[0103] In some embodiments, in active mode, the sensitivity of the
pressure sensor 194 may be mechanically, electronically, or
programmatically attenuated. For example, during active mode,
controller 400 may look for a greater pressure difference to
indicate the start of a user breath (e.g., an elevated threshold
may be compared to the detected pressure difference to determine if
the bolus of oxygen should be released). In some embodiments, the
pressure sensor 194 may be mechanically altered to be less
sensitive to pressure differences. In some embodiments, an
electronic signal from the pressure sensor may be electronically
altered to ignore small pressure differences. This can be useful
when in active mode. In some embodiments, during the inactive mode
the sensitivity of the pressure sensor may be increased. For
example, the controller 400 may look for a smaller pressure
difference to indicate the start of a user breath (e.g., a smaller
threshold may be compared to the detected pressure difference to
determine if the bolus of oxygen should be released). In some
embodiments, with increased sensitivity, the response time for
providing the bolus of oxygen during the user's inhalation may be
reduced. The increased sensitivity and smaller response time may
reduce the size of the bolus necessary for a given flow rate
equivalence. The reduced bolus size may also reduce the size and
power consumption of the oxygen concentrator 100.
Providing a Bolus Based on Inhalation Profile
[0104] In an embodiment, the bolus profile can be designed to match
the profile of a particular user. To do so, an inhalation profile
may be generated based on information gathered from pressure sensor
194 and flow rate sensor 185. An inhalation profile is assessed
based on, one or more of the following parameters: the breathing
rate of the user; the inhalation volume of the user; the exhalation
volume of the user; the inhalation flow rate of the user; and the
exhalation flow rate of the user. The breathing rate of the user
may be assessed by detecting the onset of inhalation using pressure
sensor 194 or flow rate sensor 185 as previously discussed.
Inhalation volume may be assessed by measuring the change in
pressure during inhalation and calculating or empirically assessing
the inhalation volume based on the change in pressure.
Alternatively, inhalation volume may be assessed by measuring the
flow rate during inhalation and calculating or empirically
assessing the inhalation volume based on the flow rate and the
length of the inhalation. Exhalation volume may be assessed in a
similar manner using either positive pressure changes during
exhalation, or flow rate and exhalation time. Inhalation flow rate
of the user is measured from shortly after the onset of inhalation.
Detection of the end of inhalation may be from the pressure sensor
or the flow rate sensor. When onset of inhalation is detected by
the pressure sensor, the onset is characterized by a drop in
pressure. When the pressure begins to increase, the inhalation is
considered complete. When onset of inhalation is detected by the
flow rate sensor, the onset is characterized by an increase in the
flow rate. When the flow rate begins to decrease, the inhalation is
considered complete.
[0105] There is a minimum amount of oxygen necessary for a person
to remain conscious. A person who is breathing rapidly is bringing
in a lower volume of air in each breath, and thus, requires less
oxygen enriched gas per inhalation. While there is some variation
from patient to patient, this relationship can be used to establish
the mean flow rate for each breath mathematically. By measuring a
large population of patients, the profile of the relative flow from
onset of inhalation to the onset of exhalation may be established.
Using this flow profile as a template, the calculated actual flow
based on breathing rate can be adjusted mathematically to a
calculated actual flow profile. This profile can be used to adjust
the opening and closing of the delivery valve to create an
idealized profile for the patient based on their breathing rate.
Inhalation profile data gathered from a population of users may be
used to create an algorithm that makes the appropriate adjustments
based on the detected inhalation profile. Alternatively, a look up
table may be used to control valve actuation durations and pulse
quantities based on a detected inhalation profile.
[0106] Measuring the inhalation profile of the patient provides a
more accurate basis for control of the bolus of oxygen enriched gas
being provided to the patient. For example, basing the delivery of
oxygen enriched gas on the onset of inhalation may not take into
account differences between individual users. For example, people
having a similar breathing rate can have different
inhalation/exhalation volume, inhalation/exhalation flow rates and,
thus, different bolus requirements necessary to produce the
prescribed amount of oxygen. In one embodiment, an inhalation
profile is created based on the flow rate of air during inhalation
and the duration of inhalation. The inhalation profile can then be
used as a predictor of the volume of air taken in by a specific
user during inhalation. Thus, inhalation profile information can be
used to modify the amount of oxygen enriched air provided to the
user to ensure that the prescribed level of oxygen is received. The
amount of oxygen provided to a user may be adjusted by modifying
the frequency and or duration of release of oxygen enriched gas
from the accumulator with supply valve 160. By tracking the
inhalation profile of the patient controller adjusts the delivery
supply valve actuation to idealize the bolus profile to provide the
oxygen at the maximum rate without causing wasteful retrograde
flow.
Power Management
[0107] Power for operation of oxygen concentrator system is
provided by an internal power supply 180. Having an internal power
supply allows portable use of the oxygen concentrator system. In
one embodiment, internal power supply 180 includes a lithium ion
battery. Lithium ion batteries offer advantages over other
rechargeable batteries by being able to provide more power by
weight than many other batteries.
[0108] In one embodiment, the compression system, valves, cooling
fans and controller may all be powered by an internal power supply.
Controller 400 (depicted schematically in FIG. 1) measures the
actual output voltage of the internal power supply and adjusts the
voltage to the various subsystems to the appropriate level though
dedicated circuits on a printed circuit board positioned inside the
oxygen concentrator.
[0109] In one embodiment, controller 400 adjusts the operation of
compressors 305 and 310 based on the oxygen output needs of the
user. Controller 400 may assess a preselected prescription for the
oxygen concentrator. In the embodiments shown herein, the oxygen
concentrator has a switch which is set by the user or the
prescribing doctor at the proper prescription rate (1 LPM up to 5
LPM). Controller 400 can assess the position of the switch to
determine the prescription for the subject. Based on the
prescription of the subject, the controller causes one or more of
the compressors to operate to begin production of oxygen.
[0110] In many instances, the operation energy of the oxygen
concentrator can be optimized by operating the compressors at less
than their normal maximum compressor speed. As used herein, the
phrase "normal maximum compressor speed" means the speed that the
compressor runs when the compressor is supplied with a current and
voltage that corresponds with the manufacturer's highest listed
current and voltage for proper operation of the compressor.
[0111] At low prescription rates (e.g., 1 LPM) it may not be
necessary to run both compressors to produce enough oxygen for the
user. In some instances, it may not be necessary to run the
compressor(s) at the normal maximum compressor speed. Controller
400 may be programmed to control the operation of one or more
compressors at a percentage of the normal maximum compressor speed,
wherein the percentage is assessed based on the preselected
prescription. In some instance, the selected percentage is
percentage less than 100%. If the prescription setting for the
oxygen concentrator is changed, controller 400 may adjust the
compressor speed to a different percentage of the normal maximum
compressor speed based on changes in the prescription and/or the
breathing rate of the user.
[0112] Controller 400 may further assess the breathing rate of the
subject. When providing oxygen to the user, the amount of oxygen
needed to maintain the proper prescription is based on the
breathing rate of the user. When the user has a low breathing rate
(e.g., 15 breaths per minute ("bpm") or less) then the compressor
may operate at a first percentage of the normal maximum compressor
speed. If the users breathing rate increases, it may be necessary
for the compressor to be operated at a second percentage of the
normal maximum compressor speed, which is different from the first
percentage. In this situation the second percentage will be a
higher percentage than the first percentage.
[0113] When only one compressor is being used, the controller may
arbitrarily select which compressor is operated. The selection of
the compressor may be randomized or alternated, to avoid using one
compressor more than the other compressor(s). This will help extend
the life of the compressors.
[0114] At high prescriptions, (e.g., 3 LPM or more) it may be
necessary to run more than one compressor at the same time to
provide sufficient oxygen for the user. When two or more
compressors are operated at the same time, each of the compressors
may be operated at a percentage less than the normal maximum
compressor speed. If the breathing rate of the user increases, the
speed of each compressor may also be increased. In some
embodiments, the compressors may not be capable of moving enough
air to produce sufficient oxygen for the patient when operating at
100% of the normal maximum compressor speed. Controller 400 may be
capable of sending a voltage and or current to one or more of the
compressors that is above the manufacturer's highest listed current
and voltage for proper operation of the compressor. This will cause
the compressor(s) to run at a speed above the normal maximum
compressor speed. This allows the controller to maintain proper
oxygen delivery to the patient, even when the patient's oxygen
needs exceed the normal operating parameters of the oxygen
concentrator.
[0115] In some embodiments, only one compressor may be used to
produce the oxygen needed by the patient. The compressor may be
operated at a speed that is less than the normal maximum compressor
speed. If the activity level of the patient increases the
controller may increase the speed of the compressor to increase the
production of oxygen. As the speed of the compressor approaches
100% of the normal maximum compressor speed, the controller may
start a second compressor before the first compressor reaches 100%
of the normal maximum compressor speed. Both compressors may be
operated at the same speed, or different speeds. Both compressors
may be operated at a speed that is less than the normal maximum
compressor speed. The first compressor and the second compressor
may be operated at the same percentage of the normal compressor
speed.
[0116] In an exemplary embodiment, an oxygen concentrator has two
compressors. At a prescription of 1 LPM, a single compressor is
operated at about 65% of the normal maximum compressor speed to
provide oxygen to the user, if the breathing rate is at about 12-15
bpm. The compressor that is operated is arbitrarily selected by the
controller. If the breathing rate of the subject increases above 15
bpm, the compressor speed may be increased to compensate for the
increased breathing rate. In this example, the compressor speed
remains below 100% of the normal maximum compressor speed at any
given breathing rate.
[0117] In the same exemplary system, if the prescription is
increased to 2 LPM, a single compressor is operated at about 75% of
the normal maximum compressor speed, to provide oxygen to the user,
if the breathing rate is at about 12-15 bpm. If the breathing rate
of the user increases above 15 bpm, the compressor speed is
increased up until the speed of the compressor reaches 85% of the
normal maximum compressor speed. At this point the controller turns
on the second compressor, and adjust the speed of both compressors,
so that both compressors operate at about 65% of the normal maximum
compressor speed.
[0118] In the same exemplary system, if the prescription is
increased to 3 LPM, both compressors are operated at about 85% of
the normal maximum compressor speed, to provide oxygen to the user,
if the breathing rate is at about 12-15 bpm. If the breathing rate
of the user increases above 15 bpm, the speed of both compressors
is increased. If the breathing rate approaches 25 bpm, the
compressors may not be able to provide sufficient oxygen when
operated at the normal maximum compressor speed. To provide the
proper amount of oxygen to the patient, each compressor may be
operated at a speed that is greater than the normal maximum
compressor speed. Since breathing rates at or above 25 bpm are
typically not maintained for long periods of time by the user, the
overdriving of the compressors is typically not performed for
long.
[0119] This method of controlling the compressors was shown to
improve the battery life of the oxygen concentrator. In a prior set
up, when the compressors were operated at a single speed, the
battery life for the oxygen concentrator was about 2 hours. When
the same system was updated using the control method described
above, the battery life was increased to 9 hours.
Ionized Air
[0120] Due to the size of the canister in the oxygen concentrator,
the quantity of gas separation adsorbent is small, but is capable
of producing an adequate quantity of product gas. Since the gas
separation adsorbent is optimized for maximum performance for a
specific oxygen concentrator (for example, the canister), any
significant decrease in capacity of the gas separation adsorbent
over time results in decreased product purity. One contributing
factor that may lead to a decrease in bed capacity is the
adsorption of impurities that do not completely desorb during
normal process operation, leading to the accumulation and retention
of impurities in the gas separation adsorbent. An example of such
an impurity that reduces the adsorption capacity of many zeolites
used in air separation is water.
[0121] Some stationary concentrators utilize some means of removing
water from the compressed gas before feeding the gas separation
adsorbent. Portable concentrators, by the nature of their
application, are more likely to be exposed to a wide range of
operating conditions including high humidity environments and/or
rapid temperature changes that could result in the need for more
sophisticated water rejection capabilities than implemented in
conventional portable oxygen concentrators. If water is present,
either in the form of liquid or vapor, and enters the gas
separation adsorbent, the gas adsorbent may adsorb at least some of
the water during each adsorption cycle.
[0122] When zeolites are used as the gas separation adsorbent, the
energy of adsorption of water is high relative to other types of
adsorbent. During the gas separation process not all adsorbed water
may be desorbed during evacuation/purge of the beds under typical
cycling. Therefore, complete removal of adsorbed water from gas
separation adsorbent usually entails applying some sort of energy
to the beds, such as thermal, infrared, or microwave, and purging
with a dry gas or applying a vacuum to the beds during the
regeneration process.
[0123] Although highly effective air drying systems exist in other
types of gas separation adsorbent fields, most of these systems
consume power, increase size and weight, or reduce system
efficiency in a manner detrimental to the stringent power
consumption, size/weight, and acoustic noise level requirements of
portable concentrators. Using a single process gas separation
adsorbent with some portion of the gas separation adsorbent
dedicated to impurity processing/rejection is a common method of
adding impurity rejection to a gas separation system. Adding
canisters containing gas separation adsorbent dedicated to
dehydration of the feed stream upstream of the gas separation
adsorbent or implementing layered absorbent utilizing desiccants in
addition to gas adsorbent suited for the desired gas fractionation
are also common methods of adding water rejection capacity to a gas
separation system, and can be effective in many circumstances.
However, additional canisters add significant size and weight to
the concentrator, or in the case of layered absorbents, the
desiccant layer displaces volume that could otherwise be used for
adsorbent used for highly efficient air separation or the volume of
the process columns could be decreased accordingly, and additional
power is used to compress gas through the desiccant.
[0124] Desiccants typically used for pre-drying air are also prone
to deactivation during constant cycling as well as during shutdown
periods, and are often regenerated via applying one of the
aforementioned methods. In some cases, the desiccant layer may be
advantageous, but also might not be entirely effective at
protecting the specialized adsorbents from water damage. By their
nature, personal oxygen concentrators, be they portable or
stationary, often operate in varied usage modalities rather than in
the continuous duty manner of an industrial gas production plant.
The duty cycle, storage time between use, and storage environment,
can vary widely from unit to unit. For example, home health care
providers may have a fleet of units that are stored in warehouses
that are not climate controlled while waiting for delivery to
patients for use. Similarly, patients may store units in their car
or home for a given period of time without use depending on their
individual oxygen needs. Thus, care must be used in shutting down
and storing units containing gas separation adsorbent that are run
on an intermittent basis. Any water (or other impurities) remaining
in the desiccant layer(s) or portion of the gas separation
adsorbent used for feed gas drying upon shutdown will diffuse over
time due to the gradient in chemical potential between the portion
of the bed that is used for impurity removal during normal
operation and the dry portion of the beds.
[0125] The diffusion coefficient of water in zeolites has Arrhenius
type temperature dependence, so if a concentrator is stored in a
high temperature environment the rate of intraparticle diffusion
will increase exponentially with temperature. The gas phase
diffusion rate will increase with increasing temperature as well.
Thus, in an oxygen concentrator system it is advantageous to remove
as much water as possible from the compressed gas feed stream to
prevent deactivation of the highly efficient zeolite, use less
desiccant, and minimize the presence of water in the gas separation
adsorbent during shutdown. Traditional means of removing water such
as coalescing filters and gravity water traps have limited
abilities to remove water and can thereby limit the usable service
life of oxygen concentrating equipment. The varying operating and
storage environments that portable concentrators may be exposed to
result in design challenges that more conventional gas separation
systems such as gas separation plants might not encounter and must
be addressed. As described, more efficient removal of water and/or
other impurities from gas separation adsorbent is desired.
[0126] Gas separation adsorbent (for example, zeolites) may have
two or more layers that include charged layers. A first layer may
include positively charged particles, and a second layer may
include negatively charged particles dispersed on top of the
positively charged particles, or vise versa. The negatively charged
particles may be evenly or unevenly dispersed on the first layer.
For example, water molecules may be electrostatically bound to
protons or metal cations in the zeolite. Applying current to the
gas separation adsorbent or providing charged air to the gas
separation adsorbent may change or disturb the electrostatic
charge. For example, the Gouy-Chapman model of electrical double
layer may be applied to the canisters. Disruption of the
electrostatic charge may release the water from the gas separation
adsorbent. The water may be vented from the canister. Removal of a
sufficient amount of water may recharge the gas separation
adsorbent. Thus, the gas separation adsorbent may be reused. Such
treatment of a gas separation adsorbent may extend the life of the
gas separation adsorbent and provide economical gas separation
adsorbents with good reliability.
[0127] In some embodiments, oxygen concentrator apparatus 100 may
include a canister containing gas separation adsorbent, at least
two electrodes and a power supply. FIG. 10 depicts a perspective
view of an embodiment of a canister that includes at least two
electrodes 610, 610' in canister 612. FIG. 11 depicts a top view of
the canister of FIG. 10 containing gas separation adsorbent 618.
FIG. 12 depicts an embodiment of a canister that includes at least
two electrodes 610, 610' on the outer surface of canister 612.
Electrodes 610, 610' are connected to power supply 614 by cables
616. Power supply 614 may be a separate power supply (for example,
an external power supply or a wall plug) or the same power supply
(for example, a battery) for the oxygen concentrator. Power supply
614 may provide alternating current or direct current to electrodes
610, 610'. In some embodiments, power supply may include a power
switch to turn the power supply on and off.
[0128] Electrodes 610, 610' may be flat, cylindrical or any
suitable shape. As shown in FIG. 12, electrodes 610, 610' are
positioned on an outer portion of canister 612. In some
embodiments, electrodes 610, 610' are positioned between an inner
wall and an outer wall of canister 612. Electrodes 610, 610' may be
made of materials known to be suitable for the ionization of air.
Suitable materials include, but are not limited to, platinum,
copper, nickel, doped ceramic materials or the like. In some
embodiments, electrodes 610, 610' are a single unit that includes
electrolyte material between the two electrodes.
[0129] In some embodiments, electrodes 610, 610' are removably
coupled to the canister. Using electrodes 610, 610' (and electrode
power supply) that are removably coupled to the canister allows the
electrodes to be removed after the gas separation adsorbent is
recharged. Thus, the extra weight of the power supply and/or
electrodes is not added to the weight of the portable oxygen
concentrator.
[0130] Supply of power to one of the electrodes, electrically
excites the electrode such that current flows between the two
electrodes. The current may ionize air flowing between the two
electrodes. The ionized air may contact the gas separation
adsorbent and ionize water absorbed in the gas separation
adsorbent. In some embodiments, contact of the ionized air with
bacteria absorbed on the gas separation adsorbent may kill some or
all of the bacteria present. In some embodiments, current flowing
between electrodes 610, 610' may produce sufficient heat to desorb
water from the gas separation adsorbent and/or kill bacteria in the
gas separation adsorbent. Removal of water and/or bacteria from the
gas separation adsorbent may sufficiently recharge the gas
separation adsorbent for continued use.
[0131] An embodiment of an ionization module 700 is depicted in
FIG. 13. Ionization module 700 includes top shell 710 and bottom
shell 712. Bottom shell 712 provides support for the ionization
components, while top shell 710 covers the components. Ionization
module includes an ionizer 720 which generates ionized gas (e.g.,
ionized dried air) to be used to regenerate the gas separation
adsorbent. Optionally, ionizer 720 also includes a heater (not
shown) which heats the ionized gas before delivery to the gas
separation adsorbent. An exemplary ionizer is SMC Ionizer IZN10
available from SMC Corporation of America, Noblesville Ind. During
use, ionizer 720 generates ionized gas which exits the ionizer
through ionizer outlet 722. Ionizer may be coupled to bottom shell
712 by mounting bracket 725.
[0132] Ionization module 700 also includes an interface 730 which
couples ionizer outlet 722 to an appropriate input port of an
oxygen concentrator. Interface 730 includes a support bracket 732,
a pump 734, a power cord holder 736, and a control board 738.
Support bracket 732 is mounted to bottom shell 712 and provides
support for the interface 730 components. Ionizer outlet 722 is
coupled to a pump 734 which is fitted into the tubular support of
support bracket 732. During use ionized gas from ionizer 720 enters
pump 734 which pressurizes the ionized gas and sends the gas into a
canister which is holding the gas separation adsorbent. Pump 734
and ionizer 720 are coupled to a power supply via a cord (not
shown) which is support be cord support 736. Operation of the
ionizer and the pump are controlled by control board 738. During
use, control board 738 sends control signals to ionizer 720 and
pump 734 to control the operation of these components. Control
board 738 includes an LCD screen 737 which displays information
regarding the status of the ionization module.
[0133] Ionization module is used to regenerate gas separation
adsorbent by passing ionized gas through the gas separation
adsorbent to help desorb contaminants from the adsorbent. Gas
separation adsorbent is typically disposed in a canister (as
described previously). In some embodiments, the canister is
disposed in an oxygen concentrator (e.g., a portable oxygen
concentrator apparatus, as discussed herein). In such embodiments,
a conduit is used to couple an input port of the oxygen
concentrator to the outlet of pump 734. The input port of the
oxygen concentrator apparatus receives the ionized gas from pump
734 and uses the ionized gas during a venting process to assist in
removal of contaminants (e.g., nitrogen and water) from the gas
separation adsorbent in the canister. A schematic diagram of the
interconnection of the components is shown in FIG. 14. A schematic
diagram of an alternate interconnection of the components is shown
in FIG. 15. In the ionization module of FIG. 15, the ionizer may
include a pump capable of pressuring the produced ionized gas.
[0134] In an alternate embodiment, canisters that hold gas
separation adsorbent are removable from an oxygen concentrator
apparatus. The removable canisters can be coupled to the ionization
module using appropriate couplings. An exemplary ionization module
which includes canister couplings is depicted in FIG. 16.
[0135] In this patent, certain U.S. patents, U.S. patent
applications, and other materials (e.g., articles) have been
incorporated by reference. The text of such U.S. patents, U.S.
patent applications, and other materials is, however, only
incorporated by reference to the extent that no conflict exists
between such text and the other statements and drawings set forth
herein. In the event of such conflict, then any such conflicting
text in such incorporated by reference U.S. patents, U.S. patent
applications, and other materials is specifically not incorporated
by reference in this patent.
[0136] Further modifications and alternative embodiments of various
aspects of the invention may be apparent to those skilled in the
art in view of this description. Accordingly, this description is
to be construed as illustrative only and is for the purpose of
teaching those skilled in the art the general manner of carrying
out the invention. It is to be understood that the forms of the
invention shown and described herein are to be taken as
embodiments. Elements and materials may be substituted for those
illustrated and described herein, parts and processes may be
reversed, and certain features of the invention may be utilized
independently, all as would be apparent to one skilled in the art
after having the benefit of this description of the invention.
Changes may be made in the elements described herein without
departing from the spirit and scope of the invention as described
in the following claims.
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