U.S. patent number RE36,165 [Application Number 08/801,046] was granted by the patent office on 1999-03-30 for heating and humidifying respiratory mask.
Invention is credited to R. Douglas Behr.
United States Patent |
RE36,165 |
Behr |
March 30, 1999 |
Heating and humidifying respiratory mask
Abstract
A light-weight face mask can heat and humidify inhaled air with
previously-exhaled air by passing the air through a
highly-effective and highly-efficient heat exchanger disposed
within the mask. The heat exchanger has a multitude of layers of
metallic mesh through which the air passes generally linearly. The
warm exhaled air heats the mesh which in turn heats the incoming
air before it is inhaled. Moisture from the exhaled air condenses
on the relatively-cool heat exchanger and humidifies the incoming
air. Inhaled air enters the mask generally upwardly, and exhaled
air exits it generally downwardly.
Inventors: |
Behr; R. Douglas (Midland,
MI) |
Family
ID: |
24323658 |
Appl.
No.: |
08/801,046 |
Filed: |
February 14, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
581040 |
Dec 29, 1995 |
05570684 |
Nov 5, 1996 |
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Current U.S.
Class: |
128/204.17;
128/201.13; 128/205.25; 128/206.22 |
Current CPC
Class: |
A61M
16/06 (20130101); A62B 9/003 (20130101); A61M
16/1045 (20130101); A61M 16/0683 (20130101) |
Current International
Class: |
A62B
9/00 (20060101); A62B 007/14 () |
Field of
Search: |
;128/204.17,201.13,205.25,205.27,206.17,206.24,206.19,206.22 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lewis; Aaron J.
Assistant Examiner: Srivastava; V.
Attorney, Agent or Firm: Rudy; Christopher John
Parent Case Text
.Iadd.CROSS-REFERENCE
This is a reissue of Pat. No. 5,570,684 (Nov. 5, 1996) which issued
from Ser. No. 08/581,040 which was filed on Dec. 29, 1995.
.Iaddend.
Claims
Having described my invention, what I claim is:
1. A light-weight respiratory face mask for warming and humidifying
inhaled air of a person who can wear the mask, i.e., a wearer, and
who has a head, and a face, nose, chin and mouth, efficiently with
negligible pressure differential, which comprises:
(a) an inner flexible shell capable of covering the wearer's face
from the nose to the chin, said shell capable of being spaced apart
from the wearer's face, and capable of providing an insulating air
space between the wearer's face and the mask when the mask is worn,
with peripheral edges of the inner shell able to be placed in
contact with the wearer's face to form an air seal when the mask is
worn;
(b) a heat exchanger disposed in a pocket in the inner shell
located opposite a position which can define the wearer's mouth,
and to be in open communication with the wearer's mouth, with the
heat exchanger consisting of about 15 to about 50 layers of
metallic mesh, and with each of the layers of the metallic mesh
having a surface area and a thermal conductivity within each layer
of the metallic mesh appropriate to the metallic mesh employed and
low thermal conductivity to adjacent layer(s) of the metallic mesh,
the layers being provided in a sheetlike arrangement, one layer
upon another, and being such that air can flow back and forth
across the layered arrangement in a direction from outside layer to
inside layer and from inside layer to outside layer in a direction
substantially perpendicular to the layers in the mask during
breathing by the wearer;
(c) an outer shell in a position opposite the wearer's mouth when
the mask is worn, with the outer shell having edges and joining the
inner shell above and on either side of the heat exchanger, and the
outer shell spaced apart from the heat exchanger and the inner
shell;
(d) an opening between the inner shell and the outer shell below
the heat exchanger to allow entry of air inhaled by the wearer of
the mask when the mask is worn and the wearer's head is in an
upright position upwardly, and discharge of air exhaled by the
wearer of the mask when the mask is worn and the wearer's head is
in an upright position downwardly, such that exhaled air can heat
the heat exchanger, which in turn can heat the inhaled air,
with the outer shell, the opening and the heat exchanger being
located on the mask so as to be able to reduce a tendency of the
heat exchanger to otherwise freeze in cold weather when the mask is
worn when snow is falling or blowing.
2. The mask of claim 1, wherein the outer shell protrudes less than
about 3 centimeters beyond the wearer's nose.
3. The mask of claim 1, wherein the total surface area of all of
the layers of metallic mesh in the heat exchanger is substantially
less than about two thousand square centimeters.
4. The mask of claim 1, wherein each layer of the metallic mesh of
the heat exchanger has a cross-sectional area of 6 to 24 square
centimeters.
5. The mask of claim 4, wherein the thickness of the metallic
layers is less than 2.5 centimeters when pressed together.
6. The mask of claim 1, wherein the layers of the metallic mesh are
of aluminum or brass.
7. The mask of claim 6, wherein each of the layers of the metallic
mesh is of aluminum screening which consists of aluminum wires
about 0.025 centimeters in diameter, spaced about 0.14 centimeters
apart center to center in one direction and spaced about 0.16
centimeters apart center to center in a direction perpendicular
thereto.
8. The mask of claim 1, wherein at least a portion of .[.of.]. the
outer layer of metallic mesh in the heat exchanger is at least two
centimeters above the lower edge of the opening in the mask.
9. The mask of claim 1, wherein adjacent layers of metallic mesh
are connected along at least one edge.
10. The mask of claim 4, wherein the heat exchanger is centrally
located, and the heat exchanger had a width and a height, and the
width of the heat exchanger exceeds the height of the heat
exchanger.
11. The mask of claim 10, wherein a flexible cavity is provided
within the mask for easily and quickly inserting and removing a
heat exchanger pack consisting of layers of metallic mesh.
12. The mask of claim 1, having a color of a flesh tone.
13. The mask of claim 1, having facial expressions drawn, painted,
or printed thereon.
14. The mask of claim 1, having attached to edges thereof a strap
assembly which can pass around the wearer's head so as to hold the
mask in place.
15. The mask of claim 14, wherein the strap assembly is attached
with at least one adjustable interlocking component.
16. The mask of claim 14, wherein at least a portion of the strap
assembly is elastic.
17. A respiratory face mask capable of being worn by a person,
i.e., a wearer, who has a head, and a face, nose, chin and mouth,
which mask comprises the following:
an inner flexible shell capable of covering the wearer's face from
the nose to the chin, said shell capable of being spaced apart from
the wearer's face, and capable of providing an insulating air space
between the wearer's face and the mask when the mask is worn, with
peripheral edges of the inner shell able to be placed in contact
with the wearer's face to form an air seal when the mask is
worn;
a heat exchanger disposed in a pocket in the inner shell located
opposite a position which can define the wearer's mouth, and to be
in open communication with the wearer's mouth, with the heat
exchanger including a multitude of layers of metallic mesh, the
layers being provided in a sheetlike arrangement, one layer upon
another, and being such that air can flow back and forth across the
layered arrangement in a direction from outside layer to inside
layer and from inside layer to outside layer in a direction
substantially perpendicular to the layers in the mask during
breathing by the wearer;
an outer shell having edges and joining the inner shell above and
on either side of the heat exchanger, with the outer shell being
spaced apart from the heat exchanger and the inner shell;
an opening between the .[.the.]. inner shell and the outer shell
below the heat exchanger to allow entry of air inhaled by the
wearer of the mask when the mask is worn and the wearer's head is
in an upright position upwardly, and discharge of air exhaled by
the wearer of the mask when the mask is worn and the wearer's head
is in an upright position downwardly--such that exhaled air can
heat the heat exchanger, which in turn can heat the inhaled
air--with the outer shell, the opening and the heat exchanger being
located on the mask so as to be able to reduce a tendency of the
heat exchanger to otherwise freeze in cold weather when the mask is
worn when snow is falling or blowing,
wherein the mask is light-weight and useful for warming and
humidifying inhaled air efficiently with negligible pressure
differential for the wearer.
18. The mask of claim 17, wherein the multitude of layers of the
metallic mesh in the heat exchanger is from about 8 to about 50
layers of metallic mesh, and the heat exchanger includes an outer
layer with a cross-sectional area to the outer layer of the heat
exchanger of no more than 24 square centimeters.
19. The mask of claim 18, wherein the mask has an effectiveness of
warming outside air of at least 57 percent when the outside air
temperature is 17.7 degrees Fahrenheit.
20. The mask of claim 19, wherein the effectiveness of warming the
outside air is at least 70 percent when the outside air temperature
is 33.4 degrees Fahrenheit. .Iadd.
21. In a respiratory face mask including a facepiece and a metallic
heat exchanger, said mask useful for warming and humidifying cold
outside air wherein inhaled air comes directly into the mask from
the outside air through the heat exchanger, and exhaled air goes
from inside the mask through the heat exchanger directly to the
outside air, the improvement which comprises an outer shell
attached to the facepiece in a front part of the mask with the heat
exchanger being a multi-layered metallic mesh heat exchanger
enclosed inside the mask behind the outer shell, with an opening to
the outside air provided below the multi-layered metallic mesh heat
exchanger in the outer shell of the mask for inhalation and
exhalation therethrough, wherein the opening and the multi-layered
metallic mesh heat exchanger are located on the mask so as to be
able to reduce a tendency of the heat exchanger to otherwise freeze
in cold weather when the mask is worn when snow is falling or
blowing. .Iaddend..Iadd.22. A respiratory face mask which can be
worn by a person, i.e., a wearer, who has a head, including a face,
which mask comprises the following:
an inner shell, with an edge thereof able to be placed in contact
with the wearer's face to form an air seal when the mask is
worn;
a heat exchanger disposed in the mask, including a multitude of
layers of metallic mesh, the layers being provided in a sheetlike
arrangement, one layer upon another, and being such that air can
flow back and forth across the layered arrangement in a direction
from outside layer to inside layer and from inside layer to outside
layer in a direction substantially perpendicular to the layers in
the mask, and substantially perpendicular to the face of the
wearer, during breathing by the wearer;
an outer shell, generally spaced apart from the inner shell and the
heat exchanger, which can deflect exhaled air downwardly to outside
air through an opening when the mask is worn and the wearer's head
is in an upright position;
the opening being below the heat exchanger to allow entry of air
inhaled by the wearer of the mask when the mask is worn and the
wearer's head is in an upright position upwardly, and discharge of
air exhaled by the wearer of the mask when the mask is worn and the
wearer's head is in an upright position downwardly--such that
exhaled air can heat the heat exchanger, which in turn can heat the
inhaled air--with the outer shell, the opening and the heat
exchanger being located on the mask so as to be able to reduce a
tendency of the heat exchanger to otherwise freeze in cold weather
when the mask is worn when snow is falling or blowing,
wherein the mask is useful for warming and humidifying inhaled air
efficiently,
and wherein the inhaled air comes directly into the mask from the
outside air through the heat exchanger, and the exhaled air goes
from inside the mask through the heat exchanger directly to the
outside air.
.Iaddend..Iadd.23. The mask of claim 22, wherein the multitude of
layers of the metallic mesh in the heat exchanger are from about 8
to about 50 layers of metallic mesh. .Iaddend..Iadd.24. The mask of
claim 23, wherein the multitude of layers of the metallic mesh is
of aluminum or brass. .Iaddend.
Description
.Iadd.CROSS-REFERENCE .Iaddend.
.Iadd.This is a reissue of Pat. No. 5,570,684 (Nov. 5, 1996) which
issued from Ser. No. 08/581,040 which was filed on Dec. 29, 1995.
.Iaddend.
BACKGROUND OF THE INVENTION
.Iadd.I. Field of the Invention
The present invention concerns a respiratory mask. The mask is
useful in cold weather for heating and humidifying inhaled air with
exhaled air through a heat exchanger.
II. Description of Known Art .Iaddend.
The detrimental effects of breathing cold air, particularly for
people with medical problems such as cardiac conditions, angina,
and asthma, and the benefits of heating inhaled air have been
recognized for many decades and are described in various
publications including U.S. Pat. Nos. 3,835,853; 4,325,365;
4,601,287; 4,793,343; and 4,829,997. Inhaled air has been heated
with electrical elements as taught in U.S. Pat. Nos. 2,626,343;
3,249,108; 4,601,287; 4,620,537; and 4,793,343.Iadd., .Iaddend.and
with heated water as taught in U.S. Pat. No. 5,086,766. Inhaled air
has been heated also by devices that obtain heat from portions of
the human body rather than external power sources as described
.[.is.]. .Iadd.in .Iaddend.U.S. Pat. Nos. 4,269,183, 4,473,071,
4,671,268, and 4,683,869. The advantage of heating the inhaled air
with humid exhaled air has been recognized for many decades. U.S.
Pat. Nos. 3,326,214, 3,333,585, 3,814,094, and 4,136,691, .Iadd.and
.Iaddend.4,478,215 teach heating and humidifying inhaled air
through exhaled air by passing the air through an exchanger
fabricated from either foil, a nonwoven resilient porous fibrous
organic polymeric material, a foraminous .[.heat conductive.].
.Iadd.heat-conductive .Iaddend.material, or a continuous strip of
wire netting wound helically. In addition, U.S. Pat. Nos.
4,150,671, 4,196,728, 4,200,094, 4,325,365, and 4,458,679 teach
heating inhaled air with .[.one of.]. the following: a conduit
having heat-exchanging fins; a flexible curved horn of expanding
cross section, having a flared internal chamber containing metal
mesh; a spool-like member having a series of transverse notches
which leave integral fins; an elongated curved housing in which is
disposed a plurality of pairs of spaced-apart vanes; or a
counter-current medium such as a metal sponge. U.S. Pat. No.
3,835,853 teaches an improved device for heating inhaled air with
exhaled airs which avoids ice formation at very low temperatures by
bypassing a portion of the inhaled air with an automatic valve.
Some of these patents, e.g., U.S. Pat. No. 4,478,215, teach that
the inhaled air is humidified as well as heated by the exhaled
air.
None of the disclosed devices for heating air for breathing is in
widespread use. Generally.Iadd., .Iaddend.the effective devices are
heavy and bulky. In addition, many are relatively costly to
produce.
.Iadd.Furthermore, these additional U.S. patents are cited:
U.S. Pat. No. 2,381,568--Gas Mask.
U.S. Pat. No. 2,741,246--Gas Masks.
U.S. Pat. No. 5,007,114--Humidity-retaining Mask.
U.S. Pat. No. 5,010,594--Dampening Mask for Use in Aircraft.
U.S. Pat. No. 5,433,192--Breathing Mask having a Cellulose Heat and
Moisture Exchanger Formed Therein.
U.S. Pat. No. 5,595,173--Rehumidification Filter for Ventilation
Mask.
U.S. Pat. No. 5,435,299--Respiratory Mask.
DESIDERATA .Iaddend.
Widespread use of a device for warming air that is breathed in
requires that the device be relatively small, light weight, and
inexpensive. These characteristics demand that the heat exchanger
be simple.Iadd., .Iaddend.and yet highly efficient and highly
effective.
SOME OBJECTS AND AN INTRODUCTORY SUMMARY OF THE INVENTION
The first objective of this invention is to provide a face mask
having a highly effective heat exchanger for heating and
humidifying inhaled air with exhaled air.
The second objective of this invention is to provide a heat
exchanger that is highly efficient in order to minimize weight,
bulk, and cost so that the mask is suitable for widespread use in
many activities such as shoveling snow, snow skiing, and
jogging.
The third objective of this invention is to provide a device that
offers negligible resistance to air flow.
The fourth objective of this invention is to have a relatively low
air volume and low retention of carbon dioxide.
The fifth objective of the invention is to provide simple means,
having no external power source, for reducing the tendency of the
heat exchanger to freeze in cold weather.Iadd., .Iaddend.especially
when snow is falling or blowing.
The sixth objective of the invention is to provide a device that
can easily and quickly be removed and safely washed or
sterilized.Iadd., .Iaddend.even in a dish washer.
.Iadd.As may pertain to certain embodiments of this invention, the
following is noted: .Iaddend.
The first objective was achieved, in part, by constructing a heat
exchanger from about 15 layers or more of metallic mesh, having
high surface area, high thermal conductivity within the layer, and
low thermal conductivity layer to layer. This configuration allows
a temperature differential to develop in the direction of air flow.
The first two objectives are attained in part by fabricating the
shell of the mask from a material having low thermal conductivity
and by providing a small air space between the mask and face,
except at the edges of the mask. The edges of the mask contact the
face.Iadd., .Iaddend.providing a seal that inhibits flow of air at
the edges. The second, third, and fourth objectives are attained in
part by having the heat exchanger consist of no more than about 50
layers of metallic mesh having a cross-sectional area of no more
than about 24 square centimeters, and the thickness of the
multitude of layers no more than about 2.5 centimeters when
compressed. The larger the area of the heat exchanger exposed to
the cold environment becomes.Iadd.: .Iaddend.the greater is the
cooling of the heat exchanger by means of conduction and radiation.
Therefore, limiting the cross-sectional area of the outer layer to
about 24 square centimeters contributes, in part, to the fifth
objective. The fifth objective is attained, in part, by having the
opening of the mask face generally downward so that inhaled air
enters the mask in a generally upward direction, and, in part, by
locating at least a portion of the outermost layers of mesh in the
heat exchanger several centimeters above the lower extremity of the
opening in the mask. The sixth objective is attained by the
simplicity of both the face mask and the heat exchanger disposed in
the mask, and by holding the mask in place with a strap assembly
that can be placed easily and quickly around a person's head.
BRIEF DESCRIPTION OF THE DRAWINGS
The detail of this invention and its operation together with
additional objectives can best be understood by the following
description .Iadd.taken .Iaddend.in connection with the
drawings.Iadd., .Iaddend.in which:
FIG. 1 is a front elevational view of a preferred embodiment of the
mask worn by a person.
FIG. 2 is a side elevational view of the mask of FIG. 1.
FIG. 3 is an enlarged view of a heat exchanger for the mask of FIG.
1.
FIG. 4 is a cross-sectional view of the heat exchanger taken along
line 4--4 of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT AND ADDITIONALLY
ILLUSTRATIVE DETAIL OF THE INVENTION
With continuing reference to the drawings wherein numbers indicate
components, reference number 11 indicates an inner shell of the
mask.Iadd., .Iaddend.which has low thermal conductivity and which
covers the lower portion of the face. The inner shell fits tightly
to the face around the entire peripheral edge 12 to .Iadd.form a
seal and .Iaddend.prevent air flow .Iadd.therethrough.Iaddend.. The
remainder of the inner shell is spaced apart from the face.Iadd.,
.Iaddend.providing a dead air space 13, said air space providing
thermal insulation. The air space is small in order to reduce the
amount of entrapped carbon dioxide. A highly-effective heat
exchanger 14 is centrally located approximately in front of the
mouth 15 of the wearer. Said heat exchanger comprises a multitude
of layers of metallic mesh 16, each layer having a large surface
area, high thermal conductivity within the layer, and low thermal
conductivity to adjacent layers. The collection of layers of
metallic mesh are held together as a bundle along at least one edge
by means such as a formed plastic frame 17. Said bundle of metallic
mesh fits snugly in a pocket 18 that is an integral part of the
inner shell. Because of the snug fit of the heat exchanger in the
pocket and the tight fit of the periphery of the inner shell on the
face of the person wearing the mask, essentially all inhaled and
exhaled air flows generally linearly through the multitude of
layers of metallic mesh in the heat exchanger. Outer shell 19 is
generally spaced apart from the inner shell and from the outer
extremity of the heat exchanger. The sides and top of the outer
shell 19 join the inner shell above and on each side of the heat
exchanger. The inner and outer shells are spaced apart along the
bottom of the mask.Iadd., .Iaddend.providing an opening 20. Exhaled
air is deflected downward by the outer shell and exits generally
downward from said opening.Iadd., .Iaddend.thereby reducing fogging
of glasses or goggles by exhaled air. Inhaled air enters generally
upward through said opening.Iadd., .Iaddend.thereby reducing the
tendency for snow that is falling or blowing from entering said
opening and thereby reducing clogging and freezing of the heat
exchanger. The heat exchanger is located well above the lower edge
of the opening.Iadd., .Iaddend.thereby additionally reducing loss
of heat via radiation and reducing the tendency for snow to enter
the heat exchanger and freeze .Iadd.it.Iaddend.. One should realize
that the latter two design features are relatively simple and much
more practical than heating the heat exchanger with an external
power source such as batteries or heated water. The mask can be
produced in any color including skin tones. Facial expressions such
as .Iadd.with feature .Iaddend.21 can be printed, drawn, or painted
on the front of the mask. The mask is held in place by the strap
assembly 22. It can have an elastic portion 22A .[.or.].
.Iadd.and/or .Iaddend.an adjustable interlocking portion 22B to
facilitate adjustment and removal of the mask.
Experiments were conducted to determine the effectiveness of the
invention in heating inhaled air. A commercial respirator was
modified for the experiments. Tape was placed over two input
ports.Iadd., .Iaddend.and the centrally-located output port was
enlarged to a diameter of about 4.5 centimeters. A rectangular
pocket for a heat exchanger was fabricated .Iadd.to be
.Iaddend.about 4.5 centimeters high and about 5.7 centimeters
long.Iadd., .Iaddend.and .Iadd.it .Iaddend.placed within the mask
in front of the round opening. The space around the pocket was
partially filled with a silicone caulk to hold the pocket in place
and leave a relatively small gap between the caulk and the face.
Thirty layers of metallic mesh.Iadd., .Iaddend.about 4.5 by 5.7
centimeters.Iadd., .Iaddend.were placed in the heat-exchanger
pocket. The mesh was comprised of aluminum wires about 0.025
centimeters in diameter.Iadd., .Iaddend.spaced about 0.16
centimeters apart center to center in one direction and spaced
apart about 0.14 centimeters in the perpendicular direction.
Temperature of the air was measured inside the mask immediately
adjacent to the inner layer of mesh while breathing through the
mask. Temperature measurements were made with a Digitherm
electronic indoor/outdoor thermometer. The remote sensor that was
placed inside the mask was about 0.6 centimeters .[.thick.].
.Iadd.high .Iaddend.and about 1.6 centimeters in diameter. With an
outdoor temperature of 33.4 degrees F..Iadd., .Iaddend.and a body
temperature of 97.5 degrees F., the air temperature in the mask
stabilized at 87.8 degrees F..Iadd., .Iaddend.after 2 minutes.
Assuming that the measured temperature, M, is the average of the
temperature of the air entering the mask from the heat exchanger,
H, and .Iadd.of .Iaddend.the temperature of the air breathed out of
the mouth, B, then M=(B+H)/2.Iadd., .Iaddend.and H=2M-B. In this
case, H=2(87.8)-97.5=78.1 degrees F. In this example, the mask
heated the outside air 44.7 degrees F. The most that the mask could
heat the air is 97.5-33.4=64.1 degrees F. The percent effectiveness
is 100.Iadd.% .Iaddend.times the ratio of the measured increase in
temperature to the difference between body and outdoor
temperatures. In this example, the percent effectiveness is
100.Iadd.%.Iaddend.(44.7 .Iadd.degrees F..Iaddend./64.1
.Iadd.decrees F..Iaddend.)=70.Iadd.%.Iaddend.. This data and
similar data are tabulated below. All temperatures are given in
degrees Fahrenheit, i.e., F.
______________________________________ Number of layers of mesh 30
8 16 20 30 Outside temperature 33.4 36.1 36.1 36.1 36.1 Measured
temperature 87.8 82.7 83.3 86.3 88.3 Calculated input air
temperature 78.1 67.9 69.1 74.7 79.1 Increase in temperature 44.7
31.8 33.0 38.6 43.0 Percent effectiveness 70 52 54 63 70
______________________________________ Type of mesh "standard"
"fine" none ______________________________________ Number of layers
of mesh 16 32 16 32 0 Outside temperature 17.7 17.9 18.3 18.5 18.7
Measured temperature 80.7 84.9 84.7 89.4 72.0 Calculated input air
temperature 63.9 72.3 71.9 81.3 46.5 Increase in temperature 46.2
54.4 53.6 62.8 27.2 Percent effectiveness 57 68 68 79 35
______________________________________
One can see from this data that the mask heats the inhaled air to
some extent even with no metallic mesh in the heat-exchanger
pocket, and that the amount of heating increased with increasing
number of layers to nearly 80 percent effectiveness. One can also
see that the "fine" mesh was more effective than the
.Iadd.".Iaddend.standard.Iadd.".Iaddend. mesh for a selected number
of layers. On the other hand, the "fine" mesh had about 4 times the
number of wires in a selected area.Iadd., .Iaddend.and
therefore.Iadd., .Iaddend.each layer of "fine" mesh was 4 times as
heavy as the "standard" mesh. One can also see that 32 layers of
"standard" mesh was as effective in heating air as 16 layers of the
"fine" mesh, even though 32 layers of "standard" mesh weighed half
as much as 16 layers of "fine" mesh. Even with thirty-six layers of
standard mesh in the heat exchanger, no resistance to breathing was
evident. The pressure differential between the inside of the mask
was measured while a person was breathing through it. The pressure
differential was less than about 0.02 inches of water column during
normal breathing and less than about 0.1 inches of water when
breathing was as fast as possible.
The invention accordingly .Iadd.or by incorporation of features
from originally filed claims .Iaddend.includes the following
embodiments:
A light-weight respiratory face mask for warming and humidifying
inhaled air efficiently with negligible pressure differential,
which includes the following: an inner flexible shell covering the
face from the nose to the chin, the inner shell generally spaced
apart from the face, which provides an insulating air space between
the face and the mask, with peripheral edges of the inner shell
contacting the face to form an air seal; a heat exchanger disposed
in a pocket in the inner shell located opposite the mouth, and in
open communication with the mouth, with the heat exchanger
consisting of about 15 to 50 layers of metallic mesh, each of the
layers having a high surface area and having high thermal
conductivity within the layer and low thermal conductivity to
adjacent layers; an outer shell opposite the mouth, the outer shell
joining the inner shell above and on either side of the heat
exchanger, and the outer shell spaced apart from the heat exchanger
and the inner shell; an opening between the inner shell and the
outer shell below the heat exchanger to allow entry of inhaled air
generally upward and discharge of exhaled air generally downward
such that exhaled air heats the heat exchanger which in turn heats
the inhaled air. In addition, the mask can include the following
features: its outer shell can be such as to protrude less than
about 3 centimeters beyond the wearer's nose; the surface area of
metal in the heat exchanger can be substantially less than about
two thousand square centimeters (about three hundred square
inches); each layer of the heat exchanger can have an area of 6 to
24 square centimeters; the thickness of the multitude of metallic
layers can be less than 2.5 centimeters when pressed together; the
layers of mesh can be aluminum or brass; the layers of mesh can be
aluminum screening that consists of aluminum wires about 0.025
centimeters in diameter, spaced about 0.141 centimeters center to
center in one direction and spaced about 0.159 centimeters apart in
the perpendicular direction; at least a portion of .[.of.]. the
outer layer of mesh in the heat exchanger can be at least two
centimeters above the lower edge of the opening in the mask;
adjacent layers of metallic mesh can be connected along at least
one edge; the heat exchanger can be centrally located, and the
width of the heat exchanger can exceed the height; a flexible
cavity can be provided within the mask for easily and quickly
inserting and removing a heat exchanger pack consisting of layers
of metallic mesh; it can have the color of one of the many flesh
tones; it can have facial expressions drawn, painted, or printed on
the frontal surface; it can have attached to each edge a strap
assembly which passes around the wearer's head, thereby holding the
mask in place, and the strap assembly can be attached with at least
one adjustable interlocking component, and it can have at least a
portion of the strap assembly elastic.
As can be appreciated from the foregoing and the drawings, the
layers of metallic mesh can be provided in a sheetlike arrangement,
one layer upon another. They can be such that air can flow back and
forth across the layered arrangement in a direction from outside
layer to inside layer and from inside layer to outside layer in a
direction substantially perpendicular to the layers in the mask
during breathing by the mask wearer.
And accordingly, this invention can relate to a light-weight face
mask for heating and humidifying inhaled air with
previously-exhaled air by passing the air through a
highly-effective, highly-efficient heat exchanger disposed within
the mask, with the heat exchanger consisting of a multitude of
layers of metallic mesh through which the air passes generally
linearly. The warm exhaled air heats the mesh which in turn heats
the incoming air before it is inhaled. Moisture from the exhaled
air condenses on the relatively cool heat exchanger and humidifies
the incoming air. Inhaled air enters the mask generally upwardly,
and exhaled air exits it generally downwardly.
It will be understood that certain features and subcombinations
have utility and may be used without reference to other features
and subcombinations. This is contemplated and within the scope of
my claims. It is further .[.obvious.]. .Iadd.plain .Iaddend.that
various changes may be made in details within the scope of my
claims without departing from the spirit of my invention. It is to
be understood, therefore, that my invention is not to be limited to
the specific details shown and described.
.Iadd.Accordingly, a mask of the invention can include a
multi-layered metallic mesh heat exchanger enclosed inside the mask
and has an opening below the heat exchanger in the outer shell for
inhalation and exhalation. Along these lines, the invention can
include a respiratory face mask which can be worn by a person,
i.e., a wearer, who has a head, including a face, which mask
includes an inner shell, with an edge thereof able to be placed in
contact with the wearer's face to form an air seal when the mask is
worn; a heat exchanger disposed in the mask, including a multitude
of layers of metallic mesh, the layers being provided in a
sheetlike arrangement, one layer upon another, and being such that
air can flow back and forth across the layered arrangement in a
direction from outside layer to inside layer and from inside layer
to outside layer in a direction substantially perpendicular to the
layers in the mask during breathing by the wearer; an outer shell,
generally spaced apart from the inner shell and the heat exchanger,
which can deflect exhaled air downwardly through an opening when
the mask is worn and the wearer's head is in an upright position;
the opening being below the heat exchanger to allow entry of air
inhaled by the wearer of the mask when the mask is worn and the
wearer's head is in an upright position upwardly, and discharge of
air exhaled by the wearer of the mask when the mask is worn and the
wearer's head is in an upright position downwardly--such that
exhaled air can heat the heat exchanger, which in turn can heat the
inhaled air--with the outer shell, the opening and the heat
exchanger being located on the mask so as to be able to reduce a
tendency of the heat exchanger to otherwise freeze in cold weather
when the mask is worn when snow is falling or blowing, wherein the
mask is useful for warming and humidifying inhaled air efficiently.
.Iaddend.
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