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Патент USA US2403991

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July 16,1946;
c. ,1. MURPHY péi-AL
Filed Dec. 6, 1939
5 Sheets-Sheet l
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July l6,v 1946-
Filed Dec. 6, 1939
3 Sheets-Sheet 3
Patented July 16, 1946
Cornelius J. Murphy and William P. Yant, Pitts
burgh, Pa., assignors to Mine Safety Appliances
‘Company, Pittsburgh, Pa., a corporation of
Applicationllecember 6, 1939,‘Serial No.‘ 307,783
‘3 Claims. ' (Cl. 128——-191')
This" invention’ relates to breathing apparatus,
and more particularly to the self-contained type
fering with breathing, and which is simple in
construction and operation.
Another object of this invention is to'provide
breathing apparatus which operates on the de
breathing circuit.
1 At very high altitudes, such as those encoun 5 mand principle but which is simpli?ed in'that the
apparatus requires a single breathing 'tube for
tered by aviators, the rari?ed air does not supply
in which pure oxygenilmay be supplied. to the ,
operation and includes a simpli?ed valve arrange
ment and one which is adaptable especially for
suf?cierit oxygen to sustain human life. There
fore, it is customary to furnish aviators who are
operation at low temperatures.
going to fly at such'heights with breathing appa
A further object is to ‘provide breathing appa
ratus connected to a supply of oxygen‘that makes 10
ratus which is adaptable to use with many types
up for the de?ciency in‘the air.
There are sev
eral types of breathing apparatus for this pur
pose, one of the mosteconomical being the de
mand' type in which ,oxygen‘enters the breathing
tube only during inhalation. 'This type of appa
ratus'is sometimes constructed so that part of
the unpuri?ed exhaled ai’r'may be rebreathed in
order that the supply of pure oxygen will not be
of canisters containing the chemicals for purify
ing exhaled air.
A still further object of this invention is to
provide breathing apparatus including an auxil
iary source of oxygen connected to the breathing
circuit in such a manner that the valve system
necessary for controlling the supply of oxygen is
operable at extremely low temperatures.
exhausted as quickly as otherwise. Nevertheless,
In accordance with this invention a face-piece,
there is still a waste of oxygen because the larger 20
covering the nose and mouth or the mouth alone,
share of that inhaled but not consumed by the
is connected by a breathing tube to a breathing
.body is lost with the exhaled air, whereby the
chamber or bag to which pure oxygen issupplied
service time of a given supply of oxygen is mate
rially ‘decreased.
from a suitable container. The bag, is provided
In ‘constructing the breathing apparatus de
?ne'dherein there were a number of special prob
lems that had to be solved. It was necessary that
25 with a type of valve that admits more oxygen to
' it only after the oxygen in the bag has been de
pleted to a certain extent by consumption in the
body during the course of respiration. The wall
of the breathing tube is provided with a pair of
variable atmospheric pressures and at altitudes
30 spaced valves that are adapted to be opened by
from 15,000 to 30,000 pieet where the temperature
an air-purifying canister when its‘inlet and out
is as low asminus 257°C. Such low temperatures
let are associated with the valves. The canister
cause condensation of moisture in the exhaled air
contains a suitable chemical for‘ removing the
resulting heretofore infreezing of the valve sys
dioxide from the exhaled air and liberat
terns of breathing apparatus. To be acceptable,
ing oxygen. _To prevent the exhaled air from
the apparatus must be capable of furnishing oxy
passing around the canister instead of through it,
gen while ascending from 15,000 to 30,000 feet,
the tube is provided ‘with a check valve between
remaining at the higher altitude for two hours,
the other two valves. The exhaled air in passing
and, then descending to the 15,000 foot elevation.
through the canister reacts with the chemical
All that time the apparatus must be capable of
therein and liberates oxygen which passes on to,
supplying suf?cient oxygen to support extreme
the breathing bag. Consequently, the oxygen
physical exertion and to compensate for the
that is exhaled is not lost but is reinhaled so that
psychological effects of the low atmospheric pres
less new oxygen from the container is required.
the apparatus herself-contained and operative at
sures. It likewise must not be uncomfortable to
wear nor interfere with normal operation of a
During inhalation the resistance of the canister
to air flow through it causes the check valve in
the breathing tube to open and permit the air to
pass around the canister. With this construction
only one breathing tube is required.
plane or gun, even though the seat is arranged
to swing around. in a complete circle. Satisfac
tory breathing apparatus must also be operative
inany position.
When the air-purifying canister needs replac
It is among the objects of this invention to 50 ing because of utilization of its chemical it is re
provide breathing apparatus which is especially
moved and the two valves that were held open by
suitable for high altitudes, in which substantially
it are closed, preferably automatically by springs.
Outside air, whether impure or merely ‘de?cient
no oxygen is wasted during normal operation,
which contains an air-purifying canister that can
be quickly removed and replaced without inter
in oxygen, is thus prevented from entering the
breathing tube while‘ the canister is removed.’
During the short period required for replacing
the canister the wearer breathes oxygen directly
from the breathing bag and exhales around the
edges of the face-piece, because the check valve‘
inlet and outlet valves 28 and 29 are mounted in
the tube adjacent the two passages. These two
valves are biased toward each other toward closed
position by means of coil springs 3i encircling
in the breathing tube prevents him from exhaling
their stems 32 which are slidably mounted in
back into the bag.
guides 33 in the breathing tube. Each valve has
If desired, the breathing tube valves that are
opened by the canister may be omitted as they
do not affect the operation of the apparatus while
an ‘irregularly shaped portion 34 that extends
substantially through the passage when the valve
is closed and which does not close the passage
The air-purifying can
ister '36 that is placed in the canister receptacle
vention the exhaled air, that is warmed consider-7
ably by chemical reaction in the canister, passes
contains a chemical suitable for removing car
around the above-mentioned breathing bag valve
bon dioxide from the exhaled air and liberating
to prevent any tendency for that valve to freeze
oxygen. The canister has an inlet tube 31 at its
in very cold atmospheres.
15 upper end and an outlet tube 38 at its lower
The invention is illustrated in the accompany
end which engage projecting portions 34 of the
ing drawings in which Fig. 1 is a front View,
valves and force them inwardly so that the valves
partly in section, of a portion of my breathing
are unseated, as shown in Fig. 1. The inlet and
apparatus; Fig. 2 is a fragmentary front view of
outlet tubes of the canister are encircled by seal
the canister is in place. In one form of the in
10 when the valve is open.
the lower portion of the canister receptacle and 20 ing gaskets 39 that are pressed against the walls
breathing tube connected thereto; Fig. 3 is a
of the passages. Thus, while the canister is in
fragmentary view showing the canister removed
operative position the two Valves are held open
and the valves closed; Fig. 4 is a front view of
by it so that exhaled air will pass through it and
the breathing bag and oxygen container that are
liberate oxygen that passes on to the breathing
connected to the breathing tube; Fig. 5 is an end 25 bag to add to the oxygen furnished by the oxygen
view, of the breathing bag with the oxygen con~
cylinder. Exhaled air is prevented from short
tainer removed; Fig. 6 is a front view, partly bro
circuiting around the canister through the
ken away, of a modi?cation of the breathing bag
breathing tube by an inhalation check valve 4|
assembly; and Fig. '7 is a vertical section thereof
mounted in the tube adjacent outlet valve 29.
taken on the line VII—VII of Fig. 6.
During inhalation this check valve is drawn open
Referring to the drawings, a face-piece I (Fig.
so that air can travel directly from the breath
1) of any suitable form is connected by a breath
ing tube 2 to a breathing bag 3 shown in Figs.
4 and 5. This bag is connected by an admission
valve 4, a pressure-reducing valve 6 and a pipe
‘I to the main valve 8 of an oxygen cylinder 9.
This cylinder is also provided with a by-pass valve
II that is connected by a pipe l2 directly to the
breathing tube for by-passing oxygen around the
bag in case of emergency.
ing bag to the face-piece through the breathing
tube without having to pass through the canister
which offers considerable breathing resistance.
When the chemical in the canister becomes
spent so that a new canister is required, cover 26
is unlatched from the canister receptacle and
swung downwardly to the position shown in Fig.
3. The moment this happens the pressure of the
canister against valves 28 and 29 is released and
they are closed by their springs to seal the breath
Between the oxygen
cylinder and reducing valve, pipe‘ 7 is provided
with a pressure .gauge l8.
The admission valve
ing tube against the outside atmosphere. During
4 is normally closed by a spring biased plunger
the short period that expires while the old can
ister is being removed and replaced by a new one,
the wearer inhales directly from the breathing
bag as before, but exhales between the edges of
the face-piece and his face. When the receptacle
I 4 that extends toward a bumper plate I6 on
the opposite side of the bag which engages the
plunger and thereby opens the valve whenever
the bag becomes nearly deflated by consumption
of oxygen by the body. Consequently, oxygen is
cover is closed on the new canister, the inlet and
supplied to the bag only at periodic intervals and
outlet tubes of the latter again force valves 28
is withdrawn therefrom only by the inhalations 50 and 29 open and. reestablish thev normal self
of the wearer of the face-piece.
contained breathing circuit.
It is a feature of this invention that the oxygen
Directly below the face-piece the breathing
contained in the exhaled air is retained in the
tube is provided with a shut-off valve 42 which
breathing apparatusand rebreathed so that it
is used when the apparatus is being ?ushed out.
will not be wasted but will conserve the oxygen 55 That is, the wearer'inhales, closes this valve so
in the oxygen cylinder. Accordingly, a canister
receptacle 2! is mounted on a pad '22 to which
straps 23 are connected for harnessing this part
that air can neither enter nor leave the breath
ing tube, and exhales directly into the atmos
phere by lifting the face-piece. The valve is
then opened and this process repeated a couple
of the breathing apparatus to the body of the
wearer. The breathing tube from the face-piece
more times.
leads directly to the top of this receptacle with
It will be seen that by utilizing check valve 4|
which it communicates through a passage 25 in
during exhalation to direct exhaled air through
their adjoining walls. From this passage the
the canister, and the breathing resistance of the
breathing tube extends laterally to the side of the
canister during inhalation to by-pass puri?ed air
receptacle down which a ?exible portion of the 65 around the canister, only one breathing tube
tube extends to another laterally extending por
serves for both inhalation and exhalation. This
tion below the receptacle. Hinged to the bottom
simpli?es the construction and makes the appa
of the canister receptacle is a cover 26 that is
ratus less cumbersome which is highly desirable
rigidly connected to the breathing tube below
for aircraft use.
its. central portion and with which the interior of 70
Figs. 6 and 7 show a modi?ed embodiment of
the receptacle communicates through a passage
the breathing bag assembly in which the col
2?. The breathing tube continues on from cover
lapsible breathing bag 5| is mounted in a metal
26 t0 the breathing bag.
box 52 to the back side of which the adjoining
To close passages 24 and 21 between the tube
side of the bag is secured as shown in Fig. 7..
and canister receptacle when the latter is empty, 76 Oxygen is supplied to the bag from a cylinder 53
disposed outside of the box and having a main
valve 54 connected by a pressure reducing valve
56 inside of the box to an admission valve 51
communicating with the inside of the bag. The
reducing valve is provided with a chamber 58 in
which a lever 59 is pivotally mounted at one end.
The opposite end of the lever is pivotally con
or shut in cold atmospheres, such as in high alti
tude aircraft use. This desirable result is accom
plished because the exhaled air is warmed con
siderably in passing through air-purifying canis
ter 36 of Fig. l by the chemical reaction therein,
and this warm air flows in jacket 89 around the
admission valve.
According to the provisions of the patent stat
utes, we have explained the principle and mode
nected to the lower end of an upright rod 6| sus
pended from the top of a bellows member 62.
Oxygen enters chamber 58 through a passage 63 10 of operation of our invention and have illustrated
when slidable valve member 64 is forced away
and described what we now consider to represent
from the inner end of the passage by a coil spring
its best embodiments. However, we desire to have
65, and the passage is at all times in communi
it understood that, within the scope of the ap~
cation with a pressure gauge 61 through a tube
pended claims, the invention may be practiced
58. As the pressure in chamber 58 increases it
otherwise than as speci?cally illustrated and de
expands the bellows and lifts rod 61 which swings
the projection 69 on top of lever 59 against valve
We claim:
member 64, thereby forcing it inwardly against
1. The combination with a face-piece, a breath
the inner end of valve passage 63.
ing chamber, a breathing tube connecting said
The opposite side of chamber 58 is connected 20 chamber and face-piece, and an oxygen container
by a tube ‘H to a valve chamber ‘I2 (Fig. 7) in an
for supplying the chamber with oxygen, of an air
admission valve 5'! projecting inwardly from the
purifying canister provided with an inlet and an
back side of box 52. This valve is normally closed
outlet, a pair of spaced valves mounted in the
by a spring pressed valve member 14 having a
wall of said tube and adapted to be opened by
plate 16 on its outer end. When this valve mem 25 said canister inlet and outlet when associated
ber is moved inwardly it uncovers a port 11 that
therewith, means detachably connecting the
connects chamber 12 with an inner chamber 78
canister to said valves, and an inhalation check
that is formed partly by a collapsible bellows
valve disposed in said tube between said pair of
member 19, This inner chamber is connected by
valves adjacent the canister outlet valve.
a tube Bl to the interior of the bag. ,
2. The combination with a face-piece, a
As in the ?rst embodiment, oxygen is admitted
breathing chamber, and an oxygen container for
to the bag from the cylinder only when required,
supplying the chamber with oxygen, of a breath
and likewise it is admitted only when the bag
ing tube connecting said chamber and- face-piece
collapses a predetermined amount. Accordingly,
and having two laterally spaced substantially
the free side of the bag carries a metal disc 82 35 parallel portions connected by a ?exible portion,
to which the lower end of a triangular metal plate
a canister receptacle disposed between said spaced
83 is pivotally connected. The upper end of this
portions of the tube and rigidly connected to the
plate is pivotally supported from a bracket 84
wall of one of them, said wall and receptacle
connected to the. top of the box. The upper por
being provided with a communicating passage,
tion of this plate is provided centrally with an 40 said receptacle having a removable cover rigidly
opening in which a threaded sleeve 86 is secured
connected to the wall of the other of the spaced
which contains a screw 8‘! that is adjustable ax
portions of the tube, said cover and wall being
ially therein. When the bag collapses a prede
provided with a communicating passage, a pair of
termined amount the inner end of this screw
engages end plate 16 on the admission valve and
thereby forces valve member ‘M away from port
1'! to allow oxygen to escape from the reducing
valve chamber into tube 8| and the bag.
It is a feature of this embodiment of the in
spring biased valves mounted in the tube for
closing said passages, an air-purifying canister
removably mounted in said receptacle and pro
vided with inlet and outlet portions that open
said valves when said cover is closed, and an in
halation check valve disposed in said breathing
vention that the breathing tube 2 (Fig. 6) which
connects the bag with the face-piece is connected
to the top of the box by a coupling 88 that opens
into a jacket 89 encircling the major portion of
admission valve 51. From an opening in the bot
tom of the jacket a tube 9| leads downwardly '
into the bag, this tube surrounding the smaller
tube 8| from the admission valve. By-pass valve
tube between said pair of valves.
3. Breathing apparatus comprising a face
piece, a breathing chamber, a breathing tube’con
necting said chamber and face-piece, an oxygen
container for supplying the chamber with oxygen,
the wall of said tube being provided with a pair
of longitudinally spaced openings, an air-purify
ing canister provided with an inlet and an outlet
92 (Fig. 6) on the oxygen cylinder is connected
communicating with said openings, and an in
by a tube 93 with the jacket so that oxygen may
halation check valve disposed in said tube be
be admitted directly to the bag in case the ad (30 tween said openings adjacent the canister outlet
mission valve becomes inoperative for any reason.
However, it is the purpose of the jacket to prevent
the admission valve from freezing either open
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