U.S. patent number RE36,958 [Application Number 08/975,937] was granted by the patent office on 2000-11-21 for hypobaric sleeping chamber.
This patent grant is currently assigned to Hyperbaric Mountain Technologies, Inc.. Invention is credited to Rustem Igor Gamow.
United States Patent |
RE36,958 |
Gamow |
November 21, 2000 |
Hypobaric sleeping chamber
Abstract
A portable hypobaric sleeping chamber for acclimatization to
high altitude or athletic conditioning is provided, capable of
maintaining internal pressures about 0.1 to about 10 psi below
ambient.
Inventors: |
Gamow; Rustem Igor (Boulder,
CO) |
Assignee: |
Hyperbaric Mountain Technologies,
Inc. (Boulder, CO)
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Family
ID: |
25275340 |
Appl.
No.: |
08/975,937 |
Filed: |
November 21, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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837760 |
Feb 19, 1992 |
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Reissue of: |
061275 |
May 13, 1993 |
05467764 |
Nov 21, 1995 |
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Current U.S.
Class: |
128/202.12;
128/200.24 |
Current CPC
Class: |
A61G
10/026 (20130101); A62B 31/00 (20130101); B63C
11/325 (20130101); A63B 69/00 (20130101); A63B
2208/056 (20130101); A63B 2208/12 (20130101) |
Current International
Class: |
A61G
10/02 (20060101); A61G 10/00 (20060101); A62B
31/00 (20060101); B63C 11/02 (20060101); B63C
11/32 (20060101); A61G 010/00 () |
Field of
Search: |
;128/200.24,200.12,205.26,205.28 ;600/22,21 ;482/13,148 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Pneumatic Structures, Minke & Eggers, Crosby Lockwood Staples,
London. .COPYRGT.1976. .
Levine, B.D. et al. (Apr. 1991) Medicine and Science in Sports and
Exercise 23(4), Suppl. 145. .
May, C. (Nov. 1990) "The Town That Can't Sit Still," New York
Times, p. 58. .
Richalet, J.P. Abstract 90, The Seventh International Hypoxia
Symposium. .
Escoffier, E. (1990) Everest Attempt and Acclimatization Experiment
The American Alpine Journal, pp. 303-304. .
Endo, Y. (1989) "High Mountain Research Center, Nagoya, Japan," The
American Alpine Journal, P. 266. .
Johnson, D.L., "Hearing Hazards Associated with Infrasound", in New
Perspectives on Noise-Induced Hearing Loss, Hamernik, R.P.,
Henderson, D. and Salvi, R. (eds.) 1982, 407-421. .
Slarve, R.N. and Johnson, D.L., "Human Whole-Body Exposure to
Infrasound", Aviation, Space, and Environmental Medicine (Apr.
1975), 428-431. .
Johnson, D.L., "Effects of Infrasound on Respiration", Preprints of
1973 Annual Scientific Meeting of Aerospace Medical Assn (May 1973)
37-38. .
Houston, Charles, "Going Higher, Oxygen, Man and Mountains,"
Mountaineer 4.sup.th Ed. 1998..
|
Primary Examiner: Lewis; Aaron J.
Attorney, Agent or Firm: Greenlee, Winner and Sullivan,
P.C.
Parent Case Text
This is a continuation of application Ser. No. 07/837,760, filed on
Feb. 19, 1992, now abandoned.
Claims
I claim:
1. A cylindrically-shaped hypobaric sleeping chamber with a length
longer than its diameter having a size sufficient to accommodate no
more than two reclining humans, having means for maintaining a
selected internal pressure between 0.1 and 10 psi below the local
ambient air pressure, and having means for providing fresh air to
occupants of said chamber over a period of up to eight hours, said
chamber further comprising:
(a) an air-impermeable outer layer formed of essentially
nonelastomeric material, and an inner frame of rigid or semi-rigid
material, said outer layer and inner frame when formed into said
cylindrically-shaped hypobaric chamber having sufficient strength
to withstand an external collapsing pressure of approximately 30
psig;
(b) a substantially airtight ingress and egress means through said
air-impermeable material of a size sufficient to allow a human to
pass therethrough;
(c) said means for providing fresh air comprising a vacuum pressure
release valve located in said air-impermeable material responsive
to a predetermined decrease in said internal pressure within said
hypobaric chamber below ambient pressure for pulling fresh ambient
air into said chamber;
(d) said means for maintaining said selected internal pressure
comprising a vacuum maintenance orifice located within said
air-impermeable material through which air is removed from said
chamber; and
(e) said cylindrically-shaped hypobaric sleeping chamber weighing
approximately 200 pounds or less.
2. The chamber of claim 1 having at least one window.
3. The chamber of claim 1 having an oximeter with an oxygen
alarm.
4. The chamber of claim 1 having a self-sealing door having a
vacuum gasket.
5. The chamber of claim 1 weighing less than about 100 pounds.
6. A cylindrically-shaped hypobaric sleeping chamber with a length
longer than its diameter having a size sufficient to accommodate no
more than two reclining humans, having means for maintaining a
selected internal pressure between 0.1 and 10 psi below the local
ambient air pressure, and having means for providing fresh air to
occupants of said chamber over a period of up to eight hours, said
chamber further comprising:
(a) an air-impermeable outer layer formed of essentially
nonelastomeric material, and an inner frame of rigid or semi-rigid
material, said outer layer and inner frame when formed into said
cylindrically-shaped hypobaric chamber having sufficient strength
to withstand an external collapsing pressure of approximately 30
psig;
(b) a substantially airtight ingress and egress means through said
air-impermeable material of a size sufficient to allow a human to
pass therethrough;
(c) said means for providing fresh air comprising a vacuum pressure
release valve located in said air-impermeable material responsive
to a predetermined decrease in said internal pressure within said
hypobaric chamber below ambient pressure for pulling fresh ambient
air into said chamber;
(d) said means for maintaining said selected internal pressure
comprising a vacuum maintenance orifice located within said
air-impermeable material through which air is removed from said
chamber; and
(e) said cylindrically-shaped hypobaric sleeping chamber weighing
approximately 2000 pounds or less. .Iadd.
7. A cylindrically-shaped hypobaric sleeping chamber with a length
longer than its diameter having a size sufficient to accommodate no
more than two reclining humans, having means for maintaining a
selected internal pressure between 0.1 and 10 psi below the local
ambient air pressure, and having means for providing fresh air to
occupants of said chamber, said chamber further comprising:
(a) an air-impermeable essentially nonelastomeric material forming
said chamber, whereby said cylindrically-shaped hypobaric chamber
has sufficient strength to withstand an external collapsing
pressure of approximately 30 psig;
(b) a substantially airtight ingress and egress means through said
air-impermeable material of a size sufficient to allow a human to
pass therethrough;
(c) said means for providing fresh air comprising a vacuum pressure
release valve located in said air-impermeable material responsive
to a predetermined decrease in said internal pressure within said
hypobaric chamber below ambient pressure for pulling fresh ambient
air into said chamber;
(d) said means for maintaining said selected internal pressure
comprising a vacuum maintenance orifice located within said
air-impermeable material through which air is removed from said
chamber; and
(e) said cylindrically-shaped hypobaric sleeping chamber weighing
approximately 2,000 pounds or less. .Iaddend..Iadd.8. The chamber
of claim 7 having sufficient strength to withstand an external
collapsing pressure of approximately 30 psig. .Iaddend..Iadd.9. The
chamber of claim 7 having means for providing fresh air to
occupants of said chamber over a period of up to eight hours.
.Iaddend..Iadd.10. The chamber of claim 7 weighing 200 pounds or
less. .Iaddend..Iadd.11. A cylindrically-shaped hypobaric sleeping
chamber with a length longer than its diameter having a size
sufficient to accommodate no more than two reclining humans, having
means for maintaining a selected internal pressure between 0.1 and
10 psi below the local ambient air pressure, and having means for
providing fresh air to occupants of said chamber over a period of
up to eight hours, said chamber further comprising:
(a) an air-impermeable outer layer formed of essentially
nonelastomeric material, and an inner frame of rigid or semi-rigid
material, said outer layer and inner frame when formed into said
cylindrically-shaped hypobaric chamber having sufficient strength
to withstand an external collapsing pressure of approximately 13
psig;
(b) a substantially airtight ingress and egress means through said
air-impermeable material of a size sufficient to allow a human to
pass therethrough;
(c) said means for providing fresh air comprising a vacuum pressure
release valve located in said air-impermeable material responsive
to a predetermined decrease in said internal pressure within said
hypobaric chamber below ambient pressure for pulling fresh ambient
air into said chamber;
(d) said means for maintaining said selected internal pressure
comprising a vacuum maintenance orifice located within said
air-impermeable material through which air is removed from said
chamber; and
(e) said cylindrically-shaped hypobaric sleeping chamber weighing
approximately 200 pounds or less. .Iaddend..Iadd.12. A
cylindrically-shaped hypobaric sleeping chamber with a length
longer than its diameter having a size sufficient to accommodate no
more than two reclining humans, having means for maintaining a
selected internal pressure between 0.1 and 10 psi below the local
ambient air pressure, and having means for providing fresh air to
occupants of said chamber, said chamber further comprising:
(a) an air-impermeable layer formed of essentially nonelastomeric
material, said chamber having sufficient strength to withstand an
external collapsing pressure of approximately 13 psig;
(b) a substantially airtight ingress and egress means through said
air-impermeable material of a size sufficient to allow a human to
pass therethrough;
(c) said means for providing fresh air comprising a vacuum pressure
release valve located in said air-impermeable material responsive
to a predetermined decrease in said internal pressure within said
hypobaric chamber below ambient pressure for pulling fresh ambient
air into said chamber;
(d) said means for maintaining said selected internal pressure
comprising a vacuum maintenance orifice located within said
air-impermeable material through which air is removed from said
chamber; and
(e) said cylindrically-shaped hypobaric sleeping chamber weighing
approximately 2000 pounds or less. .Iaddend.
Description
FIELD OF THE INVENTION
This invention lies in the field of hypobaric body chambers.
BACKGROUND OF THE INVENTION
For many years there has been a raging battle concerning the wisdom
of high altitude training for the low altitude athlete. Advocates
of high altitude training cited the numerous studies that all show
that the number of red blood cells increased and the aerobic
capacity increased after some extended stay at altitude, i.e.,
after acclimatization. Opponents to altitude training for the sea
level athletes, while acknowledging the increase in the hemoglobin
in these subjects, cited well-documented evidence that since the
performance of the athlete was so poor at altitude, a maximum
training regime was never possible to initiate. Thus, maximum
training could never occur. One clear solution that would answer
both objections would simply have the athlete live at altitude but
train at sea level. In this way he or she would obtain the maximum
benefit from both the high altitude and low altitude physiology.
Since de-acclimatization takes several weeks, there is virtually no
effect if the athlete descends quickly to sea level for training
and then reascends for the rest of his or her nontraining time.
This descent could be done either by physically transporting the
person to or near sea level or accomplishing the same effect via a
hyperbaric chamber.
Recently there was a report from Salt Lake City (Levine, B. D. et
al. (Apr 1991) Medicine and Science in Sports and Exercise 23(4),
Suppl. 145; and Levine, B. D. and Houston, C., "Benefits of
training at high altitude: myth or reality," The Seventh
International Hypoxia Symposium) clearly demonstrating that
athletes living at Snowbird, Utah (8,000 ft.), but training at Salt
Lake City, Utah (4,500 ft.), were significantly more fit than the
control group that both lived and trained at Salt Lake City.
Presently the Olympic Training Center (OTC) in Colorado Springs is
repeating this study and taking it further (May, C. (November
1991), "the Town That Can't Sit Still," New York Times Magazine, p.
58). The OTC is comparing and contrasting four situations: 1. Live
high and train high; 2. Live low and train low; 3. Live low and
train high; and 4. Live high and train low. These studies all deal
with determining the fitness level of athletes such as runners and
bicyclists, but there have also been several reports that high
altitude climbers that spent time in a hypobaric chamber (altitude
chamber) previous to climbing a mountain at altitude were better
acclimatized when starting the climb because of the time spent in
the hypobaric chamber (Richalet, J. P., "Effects of Acute and
Chronic Hypoxia in Human Erthropoeitin Control at Rest and
Exercise," Abstract 90, The Seventh International Hypoxia
Symposium; Escoffier, E. (1990), "Everest Attempt and
Acclimatization Experiment," The American Alpine Journal, pp.
303-304; and Endo, Y. (1989), "High Mountain Research Center,
Nagoya, Japan," The American Alpine Journal, p. 266). These two
lines of evidence both show that time spent at altitude results in
an increase in the number of red blood cells which is reflected in
the acclimatization in the mountain climbers as it also is in
athletes.
Previously-known hypobaric chambers have been large, heavy
structures with walls made of structurally rigid materials such as
concrete or metal which can simulate altitudes of 50,000 to several
hundred-thousand feet and are used for such purposes as pilot
training.
Portable hyperbaric chambers are known. For example, U.S. Pat. No.
4,974,829 to Gamow et al. discloses a spherical-shaped hyperbaric
chamber useful for physical conditioning for athletes, and a
cylindrically-shaped hyperbaric mountain bag in which mountain
climbers suffering from altitude sickness can be placed in a higher
pressure equivalent to descent to a lower altitude for alleviation
of their symptoms.
U.S. Pat. No. 5,063,924 to Galvan et al. discloses a portable
enclosed chamber for providing a controlled atmosphere which may be
pressurized to aid individuals in breathing in toxic
atmospheres.
U.S. Pat. No. 4,106,504 to York discloses a portable recompression
chamber capable of being pressurized to a desired ocean depth
pressure.
U.S. Pat. No. 3,729,002 to Miller discloses a portable, collapsible
recompression chamber for achieving ocean depth pressures.
U.S. Pat. No. 2,401,230 to Colley discloses a portable hyperbaric
chamber capable of pressurization for use during air flight at high
altitudes.
U.S. Pat. No. 1,294,188 to Stelzner discloses a portable,
collapsible decompression chamber which can be pressurized to ocean
depth pressures.
U.S. Pat. No. 4,621,621 to Marsalis discloses a portable hypobaric
device which is a respirator breathing jacket. The jacket assembly
has a screen-like grid curved to fit over the torso of the user in
spaced apart position from the torso, with an airtight poncho-like
jacket positioned over the grid. A vacuum pump and valve assembly
allows air to be alternately exhausted from and communicated into
the jacket to cause the user to inhale and exhale.
Oxygen monitoring devices are also known to the art, e.g., as
described in U.S. Pat. Nos. 4,914,424 to Hirao et al.; 4,462,246 to
Advani et al.; and 4,189,725 to Rowland et al.
None of the foregoing patents disclose a lightweight, portable
hypobaric chamber designed for only one or two reclining
persons.
DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts a preferred embodiment of the hypobaric chamber of
this invention and attached vacuum pump with a section of the outer
material of the chamber shown as though cut away to display the
inner support frame.
FIG. 2 depicts a preferred embodiment of the hypobaric chamber of
this invention having a ribbed internal frame covered with Mylar,
and steel end plates, one of which is equipped with a self-sealing
door.
SUMMARY OF THE INVENTION
A portable hypobaric chamber in cylindrical or spherical form,
sized to accommodate no more than two reclining humans is provided,
which is capable of maintaining at least about 0.1 psi below
ambient air pressures comprising:
a. a rigid air-impermeable, preferably nonelastomeric flexible
material;
b. substantially airtight ingress and egress means through said
air-impermeable material of a size sufficient to allow a human to
pass therethrough;
c. a vacuum release valve in said air-impermeable material;
d. a vacuum maintenance orifice in said air-impermeable material
through which air may be removed from said chamber.
The chamber may also comprise an internal support frame where the
air-impermeable material is not self-supporting.
The portable hypobaric chamber of this invention may be used for
both the acclimatization of the high altitude climber and as a
method to increase aerobic capacity for the athlete. This chamber
allows both the low altitude athlete and the high altitude climber
to gain the advantage of altitude acclimatization while remaining
at or near sea level. The chamber should be large enough and
comfortable enough that a person could sleep in the chamber and
thus spend perhaps as much as eight hours a day in the chamber. The
chamber of this invention weighs less than 20,000 pounds,
preferably less than 100 pounds, and more preferably less than 50
pounds, and can simulate altitudes up to three miles (approximately
16,000 ft), i.e., about 0.1 to about 10 psi below ambient air
pressure at sea level. In a preferred embodiment no carbon dioxide
scrubbers are needed. The device simply rapidly exchanges the
ambient air with the air in the chamber. This is because as the
pressure is decreased in the chamber the vacuum pressure relief
valves open, pulling in fresh air full of oxygen and simultaneously
eliminating the CO.sub.2 buildup in the bag.
The portable hypobaric chamber has a volume large enough so one or
two people may sit or lie comfortably for four to eight hours. A
cylindrical approximately six feet long and 16 inches in diameter
is a preferred minimum size for use by an adult human. A size that
appears to maximize the comfort volume with minimum bulk to
accommodate one or two users is approximately seven feet long and
approximately 31 inches in diameter, i.e., about 37 cubic feet.
The outer material of the chamber is any air-impermeable material,
preferably a fabric such as a coated nylon or mylar. Preferably the
material is essentially nonelastomeric and flexible.
The chamber is equipped with one or more vacuum release valves
which open allowing ambient air from the outside to enter the
chamber when the desired gauge pressure is obtained. The vacuum
release valves are adjusted to allow a gauge pressure from 0.1 psi
gauge to 10.00 psi gauge with the lower pressure always being in
the chamber.
An internal frame of a rigid or semi-rigid material, preferably
steel or synthetic mesh material, e.g., braided carbon composite
may be placed in the chamber. The frame may include solid (nonmesh)
portions such as metal or fiberglass end caps or plates which can
be equipped with means for ingress and egress. Preferably the frame
is slightly larger than the volume of the outer material so that
the outer material is under tension when stretched over the frame.
The outer material then helps maintain the cylindrical or spherical
shape of the frame even under hypobaric pressure. The outer
material serves to keep the ambient pressure from entering the
chamber and the internal frame keeps the chamber from collapsing.
The frame may also be slightly smaller than the outer material if
prestressing of the outer material is not required for maintaining
the shape of the chamber.
The chamber has one to several optional windows. When the outer
material is not transparent, it is preferred that it be provided
with an opening for a window wherein said window is comprised of a
transparent or translucent material which may be sewn or
heat-sealed in said opening. The chamber also has airtight means
for ingress and egress, such as a door, preferably self-sealing,
and/or a zipper when a fabric outer material is used. The zipper
placement, for optimal comfort, is at the end of the chamber placed
circumferentially around the chamber for minimum stress. When the
frame includes solid metal parts equipped with means for ingress
and egress, such means are preferably substantially airtight, e.g.,
having rubber seals such as those used on refrigeration doors. A
mylar outer material can have ingress and egress means comprising
openings closed by flaps or folding, and sealed with tape.
A vacuum pump is attached to a one-way valve for removing air from
the chamber to achieve the desired pressure. The chamber is
preferably also equipped with a pressure gauge or an altimeter and
a commercial oximeter having an O.sub.2 alarm feature.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A hypobaric chamber is provided for simulating altitudes higher
than those at which the chamber is being used. The chamber is
portable, preferably cylindrical in shape and preferably no larger
than required to accommodate two reclining adult humans. The
preferred volume is about 37 cubic feet, i.e., about seven feet
long and about 31 inches in diameter. A preferred minimum size for
use by an adult human would be about six feet long and about 16
inches in diameter. Chambers designed for use by children, animals
or other purposes may be smaller as required. The chamber may be
larger, but to maintain a preferred weight of 100 pounds or less,
in accordance with the discussion hereinafter, the size cannot be
radically increased because the strength required for the frame and
outer material goes up rapidly in proportion to the square of the
interior radius.
The chamber is capable of simulating altitudes up to about 16,000
feet, i.e., about 10 psi below ambient pressure at sea level.
Pressures in the chamber can be maintained at between about 0.1 and
about 10 psi below the ambient pressure at the location where the
chamber is used. The vacuum pump exhausts air through an outlet in
the chamber until a preset pressure level is reached within the
chamber. When the preset pressure level is passed (that is when the
pressure inside the chamber is lower than the preset level), a
vacuum release valve allows air from outside the chamber to enter
the chamber until the desired pressure is again achieved.
With the vacuum pump, which is preferably automatically powered,
running continuously, a constant supply of fresh air will enter the
chamber through the vacuum release valve so that there will be no
need to supply the user inside the chamber with oxygen from another
source or to provide other expedients for removing carbon
dioxide.
The chamber comprises an internal support frame, if needed,
preferably a grid made of a rigid or semi-rigid material such as
metal or composite plastic. To minimize the weight and maximize the
portability of the device, the grid may be less rigid than required
to maintain the chamber's shape when not in use. For example, the
grid may be comprised of thin, semi-rigid wires or strands which
allow deformation or folding of the grid when the chamber is not
pressurized. Upon achieving hypobaric pressure in the chamber, if
the chamber is spherical or cylindrical in shape, the pressure of
the outer atmosphere acting uniformly on the outer material
covering the grid will cause the chamber to assume and maintain its
shape. Thus, spherical or cylindrical shapes are preferred.
Those skilled in the art will be able, without undue
experimentation, to determine optimal strength, flexibility and
size of the openings in the grid depending on such factors as the
strength and flexibility of the outer material, the desired
internal pressure, and the size of the chamber.
The structural mechanics of thin cylindrical shells under external
pressure has been well studied and is well understood. The
following calculations show the relationship between a number of
variables such as chamber size, and strength and elasticity of the
materials used. Given the dimensions of the cylindrical chamber,
one can readily calculate the safe differential pressure between
the inside and the outside of the chamber, i.e., psig. The
pressures involved are identical to those "felt" by a cylindrical
submarine. Given the yield strength of the material (.sigma..sub.y)
and the modulus of elasticity (E), the following formula ##EQU1##
will yield the external collapsing pressure (q.sup.1). Using a
3/16" thick (t) mild steel that has been shaped into a cylinder 7
ft long with a radius (R) of 15.5", the collapsing pressure
(q.sup.1) of the cylinder will be 13 psig. Using mild steel 1/4"
thick gives a collapsing pressure (q.sup.1) of 30 psi. A chamber
with the external dimensions described above with walls of mild
steel 3/16" thick will have a safety factor of a little less than
three when ascended to an equivalent altitude of 3,000 m (9,840 ft)
from sea level. This safety factor is calculated in the following
way. At an altitude of 3,000 m (9,840 ft) the barometric pressure
is 10.2 psi, i.e., psig of 4.5 in respect to sea level. At a much
higher altitude of 5,000 m (16,404 ft) the barometric pressure is
7.8 psi, i.e., psig of 6.9 giving us a safety factor of a little
less than two. We thus suggest for simulated altitude greater than
3,000 m a wall thickness of 1/4" mild steel should be used. Such a
chamber has a collapsing pressure (q.sup.1) of 30 psig.
The calculations above describe the use of a mild steel material
only without interior supports, however, it will be apparent
therefrom to those skilled in the art how the various variables may
be changed to provide alternative embodiments of this invention. It
is important to prevent buckling of the outer material when no
internal frame is used, or of the internal frame. Using modern
composite material such as woven carbon fibers embedded in a resin
such as epoxy and adding circumferential load supporting ribs to
the cylinder allows one to use thinner and lighter materials. A
variety of preferably collapsible internal frames whose stiffness
is maintained by a series of interlocking units, some of which can
be prestressed by the outer material as described herein, are
preferably substituted for the mild steel skin. The internal frame
preferably includes annular rings made of a rigid material disposed
at least at the ends of the cylinder, and optionally spaced apart
along the length of the cylinder.
Composite plastic wands, e.g., of the type used as tent supports,
may also be used to construct an internal support, for example, by
insertion through loops or channels on the inner surface of the
outer material of the chamber. Another preferred material for
construction of the frame is braided carbon fiber composite,
available from Engineering Innovations, Littleton, Colo. This
material is available in the form of hollow pipes which can be used
to construct the frame.
Optional end caps such as shown in FIG. 1 made of a rigid material
such as metal, plastic or fiberglass may also comprise part of the
internal support frame for the chamber. In one embodiment the end
caps are designed to fit together to form a carrying case for the
chamber when collapsed.
The frame may also include rigid end plates which can be shaped to
conform to the overall cylindrical or spherical shape of the
chamber or can be flat, circular plates as shown in FIG. 2. These
plates may include ingress and egress means, such as a door,
preferably made essentially airtight by means known to the art such
as rubber seals. When the cylinder is composed of solid sheets of
material without windows, it is preferred that the end plates be of
transparent material.
The chamber also comprises an outer, air-impermeable material
disposed about said internal frame. This outer material is
preferably a flexible material such as fabric treated to be
air-impermeable or mylar. The outer material may be transparent. If
it not transparent it is preferred that the outer material be
equipped with one or more windows made of a transparent material to
allow the occupant of the chamber to look out and be viewed by
others outside the chamber monitoring its use.
The outer material should be essentially nonelastomeric so that it
is capable of maintaining hypobaric pressures within the chamber
without substantially stretching. However, it is desirable that
enough stretch be present in the material so that when it is
disposed over the internal support frame, it will be under tension.
This will help the support frame to maintain its cylindrical shape.
The outer material should not be so stretchy as to be pulled inside
the chamber to reduce the internal volume thereof to any
significant degree.
As will be appreciated by those skilled in the art, the outer
material must be strong enough not to tear when stretched over the
internal support frame or when the chamber is in use.
The outer material is air-impermeable and the entire chamber is
constructed using airtight seams and sealants if necessary so that
the chamber is substantially airtight. Minor leakage can be
tolerated because the vacuum pump is continuously or intermittently
operated, and air is permitted to enter the chamber through the
vacuum release valve to ensure fresh air in the chamber. Coated
nylon and Mylar (Trademark of DuPont) are preferred outer
materials.
In the embodiment of FIG. 2, transparent Mylar is used, preferably
of a thickness of 3 mil. Other transparent materials known to the
art may also be used provided they have sufficient strength to
withstand the pressure difference between the interior and exterior
of the chamber.
In another embodiment, the entire cylinder, except for the ends, is
constructed of a solid sheet of rigid material, preferably a carbon
fiber composite material in sheet form. Preferably this material
comprises two sheets of composite separated by a layer of aluminum
honeycomb. This material may be supported by internal ribs if
required, but preferably is stiff enough, i.e., has a yield
strength great enough, not to require internal supports.
The vacuum release valve can be of any construction known to the
art for permitting air to enter the chamber from the outside when a
predetermined pressure has been reached. A standard pressure
release valve inserted into the outer material of the chamber in an
orientation opposite to that used for hyperbaric devices is
suitable for this use. The valve can be adjustable by the user to
various pressures, or can be capable of opening only at a single
pressure preset for the chamber when the chamber is constructed.
The valve must be capable of opening at a difference between the
inside and outside pressure of between about 0.1 and 10 psi.
It should be appreciated by those skilled in the art that because
the valve responds to differences between the pressures inside and
outside the chamber, when the chamber is used at altitude, the
pressure release valve must be set to respond to a lower pressure
difference than when the chamber is used at sea level. It is
desirable that the pressure inside the bag not be less than
equivalent to about 15,000 to 16,000 feet of altitude.
The hypobaric chamber of this invention also comprises
substantially airtight means for ingress and egress, preferably of
a size sufficient to allow an adult human to enter and exit the
chamber. Preferably these means comprise substantially airtight
zipper means when a fabric outer material is used, preferably
disposed along an axis perpendicular to the long axis of the
cylindrical chamber, and preferably positioned near one end of the
chamber. A door in the frame, preferably in a rigid plate portion
of the frame such as the flat, circular end plate described above,
can also be used, preferably a self-sealing door similar to a
refrigerator. When an outer material such as mylar is used,
openings closed by flaps or folding and sealed with tape may be
used.
As will be readily appreciated, the openings in the outer material
must coincide with openings in the internal frame such as those
discussed above.
Airtight zippers are known to the art and include zippers
manufactured by Talon and YKK of rubber or steel.
As will be appreciated by those skilled in the art, other
ingress/egress means may be used so long as they are substantially
airtight when the chamber is in use. As discussed above, some
leakage in the chamber can be tolerated so long as it does not
exceed the vacuum pump's ability to maintain the desired hypobaric
pressure within the chamber.
The chamber is also equipped with a vacuum maintenance orifice. The
vacuum pump is connected to this opening and air exits the chamber
through this opening. The vacuum maintenance orifice may be
equipped with check valve means allowing hypobaric pressure to be
maintained within the chamber when the vacuum pump is not
operating. Such valve means are necessary when a manually-operated
pump rather than a gasoline-powered, electrically-powered or other
automatically-powered vacuum pump is used, or when such an
automatically-powered pump is operated intermittently.
The hypobaric chamber of this invention is preferably portable,
weighing 100 pounds or less, and preferably 50 pounds or less.
Preferably the chamber is constructed of flexible, foldable outer
material and a lightweight, foldable or disassembleable inner
support frame, e.g., a lightweight metal composite or plastic grid,
or a series of wands which can be assembled to form the frame and
disassembled for transportation and storage.
The chamber may include rigid end caps, and these may be equipped
with handles and fasteners such that they fit together to form a
carrying case for the chamber. Such a carrying case may optionally
be of a size large enough to accommodate the vacuum pump as well as
the chamber itself so that the entire system is self-contained.
As will be appreciated by those skilled in the art, the chamber
may, if desired, be equipped with oxygen supply and carbon dioxide
scrubber means.
An oximer with an alarm is preferably also included in the chamber
so as to alert the user or those monitoring use of the chamber when
the oxygen content of the air in the chamber falls below optimal
breathing levels. Such devices are known to the art and are
commercially available. An alarm may also be provided which
responds to power failures to alert the user if the electrical
power to the vacuum pump goes off.
The inside of the chamber may be equipped with a mattress and
bedding materials for the comfort of the user sleeping in the
chamber. Optional legs may be added to keep the chamber from
rolling.
The chamber of this invention may also be equipped with an inner
bladder such as that described in U.S. Pat. No. 5,109,837,
incorporated herein by reference. In this instance, air enters the
chamber through the vacuum release valve, and is breathed in
through a first one-way valve into a mask affixed to the user's
face. The mask is also equipped with a second one-way valve through
which air is breathed out into the inner bladder, the inner bladder
is connected through an opening in the outer material of the
chamber to a vacuum pump which may be a bicycle or raft pump or an
automatically-powered pump. As the inner bladder is emptied, the
pressure inside the chamber falls below the preset level and the
vacuum release valve allows air to enter the chamber, thus
supplying the user with a constant supply of fresh air. The user
breathes only previously unbreathed air from the inside of the
chamber and exhales used air only into the inner bladder. Use of
the bladder allows operation of the pump to be decreased. When a
manually operated pump is used, the number of pumps required per
minute is substantially decreased.
An embodiment of the hypobaric chamber of this invention is shown
in FIG. 1. The chamber is comprised of an outer material 10 which
is disposed or stretched over internal frame 20. The chamber may
optionally be equipped with windows 30. A pressure gauge or
altimeter 40 may be attached to the chamber for determining the
pressure inside the chamber. The chamber is also equipped with a
vacuum release valve 50 which allows ambient air to enter the
chamber when further air is removed from the chamber by vacuum pump
60 through vacuum maintenance orifice 90 after the desired
hypobaric pressure inside the chamber has been reached, so as to
maintain the pressure inside the chamber at a preset level. The
chamber is also equipped with a zipper 70 to allow a human to enter
and exit the chamber. Optionally the ends of the chamber beneath
the outer material are equipped with rigid caps, which in their
entirely comprise, or are equipped with, a self-sealing door
80.
The chamber is used for hypobaric athletic conditioning as a
sleeping chamber. The user enters the chamber through airtight
zipper 70 which may be opened and closed from both inside and
outside the chamber. The vacuum release valve 50 is preset to a
selected hypobaric pressure. For use at sea level, preferred
pressures are between about 2 psi and about 7 psi below ambient.
For use at high elevations such as 5,000 feet, preferred athletic
conditioning pressures are between about 2 psi and about 3 psi
below ambient. When the chamber is used for acclimatization to high
altitude, pressures between about 5 psi and about 10 psi below
ambient are selected.
The vacuum pump is activated. The vacuum pump is connected to the
chamber through an orifice in the outer material of the chamber. If
the internal frame contains a rigid member, there may be a
corresponding orifice therein to allow connection to the pump.
Preferably the pump is an automatically-powered pump rather than a
manual pump. Air is exhausted from the chamber by the pump until
the preset hypobaric pressure is achieved within the chamber. The
outer material 10 of the chamber is pressed against the internal
frame 20 by the outer air pressure acting against the lowered
pressure within the chamber. The cylindrical shape of the chamber
allows the pressure against the outer material to be uniformly
distributed around the circumference of the chamber, thus
preventing local deformation of the internal support frame. In use
the chamber maintains a uniformly cylindrical shape.
The optional end caps 80 help maintain this shape. The optional
windows 30 can be used for viewing the occupant inside the chamber
or for the occupant's use in seeing out of the chamber.
Pressure gauge 40 which may be placed inside or outside the chamber
allows the user or others to monitor the pressure inside the
chamber and make adjustments if required.
An optional oximeter having an alarm feature warns the user or
person monitoring the use of the bag if the oxygen level falls
below that required for breathing at the desired pressure inside
the chamber.
When not in use, in a preferred embodiment, the chamber may be
collapsed and stored inside rigid caps 80 which can be equipped
with handles and fastenings such that they comprise a carrying case
for the chamber.
FIG. 2 shows a preferred embodiment of this invention. The chamber
is covered with a transparent outer material 110, preferably Mylar
(trademark of DuPont). The material needs to cover only the sides
of the cylindrical chamber and not the ends.
The ends of the chamber are covered by metal (preferably steel) end
caps 180, one of which is equipped with a self-sealing door 170
having a vacuum gasket 175.
The internal frame of the chamber is constructed of metal,
preferably steel, ribs 130 in the form of annular rings, over which
is placed wire mesh 120. Structural supports 135 in the form of
horizontal rigid members may also be used.
The chamber is equipped with a vacuum release valve 150 in end cap
180. The end cap 180 on the opposite side of the chamber is
equipped with an exhaust port, or vacuum maintenance orifice 190
connected by a hose to a vacuum pump (not shown).
The chamber is also equipped with support legs 160 to prevent
tipping and rolling.
As will be appreciated by those skilled in the art, there are many
modifications which may be made to the basic design described above
all within the scope and spirit of this invention.
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