U.S. patent application number 10/537722 was filed with the patent office on 2006-03-09 for breathing apparatus.
Invention is credited to David Hodson, Paul Townsend.
Application Number | 20060048774 10/537722 |
Document ID | / |
Family ID | 32507931 |
Filed Date | 2006-03-09 |
United States Patent
Application |
20060048774 |
Kind Code |
A1 |
Townsend; Paul ; et
al. |
March 9, 2006 |
Breathing apparatus
Abstract
A face mask (10) mechanically coupled to a lung demand valve
(LDV) (12). The face mask (10) comprises a main mask and an inner
mask (15) which fits over the wearer's mouth and nose. The interior
of the inner mask (15) is in fluidic communication with the
interior of the main mask (10) by means of non-return valves (16).
The interior of the main mask is in fluidic communication with an
inlet port (18) which is mechanically and fluidically coupled to a
supply port (20) of an LDV. The LDV (12) includes a diaphragm and a
cover (44) which comprises three parts (44a, 44b) and (44c).
Exhaled air is used to flush the space around the diaphragm. Thus,
any toxic or undesirable gas in the vicinity of the diaphragm is
pushed out to atmosphere by the exhaled air flowing past and around
the diaphragm.
Inventors: |
Townsend; Paul; (Jesmond,
GB) ; Hodson; David; (Whitley Bay, GB) |
Correspondence
Address: |
CAESAR, RIVISE, BERNSTEIN,;COHEN & POKOTILOW, LTD.
11TH FLOOR, SEVEN PENN CENTER
1635 MARKET STREET
PHILADELPHIA
PA
19103-2212
US
|
Family ID: |
32507931 |
Appl. No.: |
10/537722 |
Filed: |
December 9, 2003 |
PCT Filed: |
December 9, 2003 |
PCT NO: |
PCT/GB03/05346 |
371 Date: |
August 1, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60432454 |
Dec 11, 2002 |
|
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|
Current U.S.
Class: |
128/200.24 |
Current CPC
Class: |
A62B 18/10 20130101 |
Class at
Publication: |
128/200.24 |
International
Class: |
A62B 9/00 20060101
A62B009/00; A61M 16/00 20060101 A61M016/00 |
Claims
1. A lung demand valve device for use with breathing apparatus, for
delivering breathable gas from a pressurised supply to a user
wearing a face mask, for inhalation, the device comprising a body
in which is housed a valve member, for controlling the rate of
delivery of the breathable gas, a movable diaphragm having a first
face exposed to pressure within the body and a second face exposed
to pressure outside the body, the diaphragm being responsive to the
differential in pressure between its first and second faces to
control the valve member, and a duct arranged to direct exhaled air
towards said second face of said diaphragm.
2. A device according to claim 1 wherein the device is detachably
mountable on a mask of a breathing apparatus.
3. A device according to claim 1 wherein the device is permanently
attached to a mask of a breathing apparatus.
4. A device according to claim 1 wherein the device is integral
with a mask of a breathing apparatus.
5. A device according to claim 1 wherein the duct portion is
arranged to abut an exhalation port of a mask.
6. A device according to claim 1 wherein the duct is arranged to
direct exhaled air to a region surrounding the second face of the
diaphragm, so as to flush ambient gases from said region.
7. A device according to claim 1 wherein the device comprises a
cover member arranged to extend around the device for preventing
the ingress of dirt into the housing, and wherein the duct
comprises a portion of said cover.
8. A device according to claim 7 wherein said cover comprises a
plurality of portions which portions are detachably fixed
together.
9. A device according to claim 1 wherein the device comprises
locating means arranged to co-operate with a mask to inhibit
rotation of the device relative to a mask.
10. Self-contained breathing apparatus including a lung demand
valve device according to claim 1.
11. A lung demand valve suitable for use in a self contained
breathing apparatus, in which fluid for breathing is conveyed to a
user on inhalation, the lung demand valve comprising: a first fluid
path, a second fluid path, a flexible diaphragm, separating the
first and second fluid paths, and wherein the second fluid path is
open to the atmosphere.
12. A cover suitable for use on a lung demand valve for a self
contained breathing apparatus, in which fluid for breathing is
conveyed to a user on inhalation, in which the lung demand valve
comprises: a first fluid path, and a diaphragm, enclosing at least
a part of the first fluid path, wherein the cover provides the lung
demand valve with a second fluid path, so that the first and second
fluid paths are separated by the diaphragm, and the second fluid
path is open to the atmosphere, and wherein exhaled fluid is
directed along the second fluid path to the diaphragm.
13. A self-contained breathing apparatus in which fluid for
breathing is conveyed to a user on inhalation, the apparatus
comprising: a face mask, connected to a lung demand valve, and worn
by the user, a high pressure cylinder containing the fluid for
breathing, a hose for conveying fluid from the cylinder to the lung
demand valve, wherein the lung demand valve comprises: a first
fluid path for conveying fluid for inhalation to the face mask, a
second fluid path for conveying exhaled fluid from the face mask to
the atmosphere, and a flexible diaphragm, separating the first and
second fluid paths, wherein exhaled air is directed to the
diaphragm.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to self-contained breathing
apparatus (SCBA) and particularly to breathing apparatus utilising
a face mask and a second stage regulator, or so-called
lung-demand-valve (LDV).
[0002] In a SCBA set breathing gas (usually air) is stored at a
first, "high" pressure in a pressurized cylinder. From the cylinder
the gas is conveyed to the user for breathing via at least one
stage of regulator, in which the gas is reduced in pressure. It is
preferable to have two stages of regulator each of which reduces
the pressure. In such a system the first reduction in pressure
takes place, as the gas leaves the cylinder, in a first stage
regulator. The gas is stored in the cylinder at a pressure of
typically up to 200 to 300 bar and after the first stage of
pressure reduction has a pressure in the order of 7.5 bar. The gas
is then considered to be at "medium" pressure. The medium pressure
gas is then conveyed to a second stage regulator, usually a lung
demand valve conveniently mounted on a face mask of a user. Here
the gas is reduced in pressure to a slightly super-atmospheric
pressure, at which the gas is breathable.
[0003] The lung demand valve is actuated by the breathing of the
wearer of the mask, such that as the wearer inhales a diaphragm is
displaced causing a valving member to open allowing breathable gas
into an expansion chamber, from which it may be drawn into the
lungs of the user.
[0004] An example of such apparatus is illustrated in schematic
sectional view in FIG. 1, in which a face mask 10 is mechanically
coupled to a lung demand valve 12, which in turn is in fluidic
communication with a cylinder of breathing gas 13 via a hose 14.
The face mask 10 comprises an inner mask 15 which fits over the
wearer's mouth and nose. The interior of the inner mask 15 is in
fluidic communication with the interior of the main mask 10 by
means of so-called "oranasal" non-return valves 16, mounted on
either side of the inner mask, and the interior of the main mask is
in fluidic communication via vents (not shown) with an inlet port
18 of the mask. The mask inlet port 18 is mechanically fluidically
coupled to a supply port 20 of the LDV. The LDV 12 itself includes
a valving member, a valve seat (neither shown) and an expansion
chamber 22. The valving member is biased in the "valve closed"
position in which it bears against the valve seat. However, the
valving member may be displaced from the valve seat to allow medium
pressure compressed air into the chamber 22 by movement of an
actuator arm 24 mounted pivotally on the LDV. The compressed air
arrives at the LDV from a rubber hose coupled to the LDV at medium
pressure (approximately 7.5 bar). A distal end 24A of the arm bears
against the diaphragm member 26 comprising a flexible apron portion
26A and, in the centre, a relatively rigid disc portion 26B. The
apron portion 26A is mounted around its periphery in a
correspondingly shaped housing portion 28 of the LDV. Beneath it is
a spring 30 which exerts a biasing force on the diaphragm to keep
the actuator arm 24 normally in such a configuration that the valve
is slightly open. On the same side of the diaphragm as the spring
30 the housing portion 28 is open to atmosphere, through a rubber
dust cover 32 which is clipped over the housing 28 to keep dust or
other ambient particulates from contacting the diaphragm 26.
[0005] In equilibrium, the spring 30 positions the diaphragm 26 and
hence the actuator arm 24 so that the valve is partially open.
Accordingly, breathable gas, at slightly super atmospheric
pressure, flows into the chamber and hence to the mask inlet port
18 at a constant, limited rate, and the pressure inside the LDV
keeps the spring and diaphragm in an equilibrium position. As soon
as the wearer of the mask inhales, a reduction in the pressure
inside the mask 15 occurs. This reduction is transmitted to the LDV
chamber 22. The diaphragm is in fluidic communication with the
atmosphere through holes 34 in the base of the LDV housing. When
the air pressure in the chamber 22 falls below the equilibrium,
super-atmospheric pressure, the spring 30 is able to push the
diaphragm, causing it to rise, which in turn causes the actuator
arm 24 to rise until they adopt the position shown in FIG. 1. The
result of this is that the compressed air flows into the chamber 22
at a greater rate during inhalation. Once inhalation has ceased the
pressure in chamber 22 builds again to resume the equilibrium state
of slightly super-atmospheric pressing down on the diaphragm and
countering the force of the spring 30. This causes the actuator arm
to urge the valve towards an equilibrium position in which the flow
of breathable gas into the chamber 22 is reduced again.
[0006] In this way the valve acts to supply breathable air to the
lungs of the wearer but "on demand", whilst keeping a constant low
level of supply to maintain a positive (i.e. super atmospheric)
pressure in the mask at all times, even during non-inhalation
phases, so as to resist the ingress of smoke and noxious gases into
the mask around its sides.
[0007] FIG. 2 shows schematically the exhalation phase. In the LDV
the pressure in chamber 22, i.e. of air for inhalation, and spring
30 maintains the diaphragm 26 and actuator arm 24 in an equilibrium
position shown in FIG. 2. Meanwhile, exhaled air in the inner mask
15 builds in pressure and at a one-way exhalation valve 36
overcomes a biasing spring 38 to allow an exhale valving member 40
to be displaced from its seat 42. The exhaled air is simply vented
to atmosphere to outlets 39. Once exhalation ceases, the pressure
of exhaled air in the face mask falls and biasing spring 38 closes
the exhalation valve 36. The cycle of inhalation and exhalation
then continues.
[0008] For the LDV to function, the diaphragm must be exposed to
the external atmosphere on one side. In atmospheres containing
relatively high concentrations of toxins it is conceivable that the
external face of the diaphragm might be subjected to a gradual
build up of toxins. Since the apron of the diaphragm is a thin
membrane, typically of rubber or silicone, concerns have been
expressed that in exceptional cases if the diaphragm faces this
exposure repeatedly or for long periods this could lead to toxins
diffusing through the membrane.
SUMMARY OF THE INVENTION
[0009] Accordingly, a need exists for an LDV and/or LDV/mask
combination in which the likelihood of such a build up of toxins on
the external face of the diaphragm is minimised or eliminated.
[0010] According to one aspect of the invention there is provided a
lung demand valve device for use with breathing apparatus, for
delivering breathable gas from a pressurised supply to a user
wearing a face mask, for inhalation. The device comprises a body in
which is housed a valve member, for controlling the rate of
delivery of the breathable gas, a movable diaphragm having a first
face exposed to pressure within the body and a second face exposed
to pressure outside the body. The diaphragm is responsive to the
differential in pressure between its first and second faces to
control the valve member. A duct is provided and arranged to direct
exhaled air towards the second face of the diaphragm.
[0011] The device may be detachably mountable on a mask of a
breathing apparatus. Alternatively the device may be permanently
attached to a mask of a breathing apparatus. In an alternative
arrangement the device is integral with a mask of a breathing
apparatus.
[0012] The duct portion may be arranged to abut an exhalation port
of a mask. The duct may be arranged to direct exhaled air to a
region surrounding the second face of the diaphragm, so as to flush
ambient gases from that region.
[0013] Preferably the device comprises a cover member arranged to
extend around the device for preventing the ingress of dirt into
the housing, and wherein the duct comprises a portion of the cover.
The cover may comprise a plurality of portions which portions are
detachably fixed together.
[0014] Preferably the device comprises locating means arranged to
co-operate with a mask to inhibit rotation of the device relative
to a mask.
[0015] According to another aspect of the present invention there
is provided a lung demand valve suitable for use in a self
contained breathing apparatus, in which fluid for breathing is
conveyed to a user on inhalation. The lung demand valve comprises a
first fluid path, a second fluid path, a flexible diaphragm,
separating the first and second fluid paths, and wherein the second
fluid path is open to the atmosphere.
[0016] According to a still further aspect of the present invention
there is provided a cover suitable for use on a lung demand valve
for a self contained breathing apparatus, in which fluid for
breathing is conveyed to a user on inhalation. The lung demand
valve comprises a first fluid path, and a diaphragm, enclosing at
least a part of the first fluid path. The cover provides the lung
demand valve with a second fluid path, so that the first and second
fluid paths are separated by the diaphragm, and the second fluid
path is open to the atmosphere, and wherein exhaled fluid is
directed along the second fluid path to the diaphragm.
[0017] According to a still further aspect of the present invention
there is provided a self-contained breathing apparatus in which
fluid for breathing is conveyed to a user on inhalation. The
apparatus comprises a face mask, connected to a lung demand valve,
and worn by the user, a high pressure cylinder containing the fluid
for breathing, a hose for conveying fluid from the cylinder to the
lung demand valve. The lung demand valve comprises a first fluid
path for conveying fluid for inhalation to the face mask, a second
fluid path for conveying exhaled fluid from the face mask to the
atmosphere; and a flexible diaphragm, separating the first and
second fluid paths, wherein exhaled air is directed to the
diaphragm.
[0018] Preferably the second fluid path is provided by a removable
cover positioned over the lung demand valve.
[0019] The cover may be made of chemically resistant material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] A preferred embodiment of the present invention will now be
described, by way of example only, with reference to the
accompanying drawings in which:
[0021] FIG. 1 is a schematic sectional view of a prior known
breathing mask and LDV in a first configuration,
[0022] FIG. 2 is a view of the mask of FIG. 1 in a second
configuration,
[0023] FIG. 3 is a side view of mask and LDV according to one
exemplary embodiment of the invention,
[0024] FIG. 4 is a front prospective view of the LDV of FIG. 3,
and
[0025] FIG. 5 is a schematic sectional view of the mask and LDV of
FIGS. 3 and 4.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0026] Turning to FIG. 3, this is a side view of a mask and LDV
constructed in accordance with one exemplary preferred embodiment
of the present invention. In particular, FIG. 3 shows a mask 10, an
LDV, generally represented by 12, a cylinder 13 and hose 14, and an
inner mask 15 complete with non-return valve 16. The mask 10, LDV
12 cylinder 13 and hose 14 are identical to the equivalents shown
in FIGS. 1 and 2 and, during an inhalation phase, they operate in
the same manner as the prior art apparatus described above.
[0027] However, in accordance with the present invention the LDV 12
is provided with a cover 44 which comprises three parts, namely, a
yoke, 44a, a rubber cover portion 44b and a rigid plastic duct
portion 44c.
[0028] The rigid plastic yoke 44a extends across the top of the
supply port (not shown) of the LDV and is secured by screws 46
(only one of which is shown in FIG. 3). The screws are located on
both sides of the yoke and threadedly engage the rigid plastic duct
portion 44c. Stretched between the yoke 44a and the rigid plastic
duct portion 44c across the front and underside of the LDV is the
rubber cover portion 44b. In particular, the flexible rubber cover
portion 44b is trapped between the yoke 44a and duct 44c at its
upper end, and engages lugs (not shown) on the duct 44c at its
lower end. A gap in the cover portion 44b reveals a compressed air
intake port 48 which in the interest of clarity is shown in this
figure unconnected to any delivery hose.
[0029] FIG. 4 shows generally the LDV 12 in a front perspective
view. In FIG. 4, only parts 56, 58, and 60 of the face mask 10 to
which the LDV is coupled are shown by hatched lines in the interest
of clarity. A portion 50 of pressurised rubber hose is also shown
connected to the intake port 48 of the LDV cover through which
"medium" pressure air is supplied to the LDV.
[0030] FIG. 5 shows a cross-sectional view of the mask. As the
wearer exhales, an increased pressure is created in the inner mask
14. The increased pressure in the face mask lowers the diaphragm 26
in the LDV, temporarily closing the air supply. As the user
breathes out, the exhalation valve 36 opens and allows the exhaled
air to pass out of the mask 10 through outlet port 39. Since the
duct portion 44c of the cover 44 abuts directly the port 39,
exhaled air is retained within and directed by the cover 44. The
air then flows over the diaphragm 26, and is eventually vented to
the atmosphere through exit slots 52. When the user ceases
exhaling, the exhalation valve 36 is urged shut by the spring 38,
thus closing the exhalation port 39 to the atmosphere. The user
then breathes in, and the process described above in relation to
FIG. 1 is repeated.
[0031] Accordingly, exhaled air which in the prior art apparatus
would be vented directly to the atmosphere is used to flush the
space around the diaphragm. Thus, any toxic or undesirable gas in
the vicinity of the diaphragm is pushed out to atmosphere by the
exhaled air flowing past and around the diaphragm.
[0032] In the prior art LDV and mask the LDV is free to rotate in
relation to the mask whilst remaining coupled thereto. Clearly in
the apparatus according to the present invention the LDV must not
be permitted to rotate with respect to the mask, since such
rotation would displace the duct 44c from the exhalation port 39
and thus the exhaled air would undesirably vent directly to
atmosphere before flushing the diaphragm 26.
[0033] To maintain the abutment of the duct 44c to the exhalation
port 39, the yoke portion 44a of the cover is provided with two
upstanding lugs 54 (see FIG. 4) which lie either side of a pair of
similar lugs 56 on the face mask which are provided as standard
items to protect a release button 58, located on the mask from
being inadvertently depressed.
[0034] The juxtaposition of lugs 54 and 56 respectively on the yoke
portion of the LDV cover and on the face mask, prevents rotation of
the LDV, and hence the duct 44c, with respect to the mask.
[0035] While the invention has been described in detail and with
reference to specific examples thereof, it will be apparent to one
skilled in the art that various changes and modifications can be
made therein without departing from the spirit and scope
thereof.
* * * * *