Note: Descriptions are shown in the official language in which they were submitted.
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Oxygen breathing device and method for maintaining an emergency oxygen system
The invention relates to an oxygen breathing device, comprising an oxygen
source, in
particular a chemical oxygen generator or an oxygen pressure tank, at least
one oxygen
mask connected via an oxygen supply line to said oxygen source, a flow control
unit
adapted to receive a signal indicating ambient pressure or to detect ambient
pressure and
5 to control the flow of oxygen through the oxygen supply line depending on
said ambient
pressure, wherein the flow control unit is adapted to provide a low oxygen
flow at a first
ambient pressure, provide a higher oxygen flow at a second ambient pressure
which is
lower than said first ambient pressure and to increase said oxygen flow in at
least two
steps, preferably to increase said oxygen flow constantly.
10 A further aspect of the invention is a method for providing oxygen to a
passenger of an
aircraft and a method for maintaining an emergency oxygen system of an
aircraft.
Generally, emergency oxygen supply systems for passengers of an aircraft are
known.
Such systems are used to supply oxygen to passengers in case of a pressure
drop within
the cabin or other emergency or critical situations, where the oxygen present
in the cabin
15 of the aircraft is not sufficient for the vital functions of the
passenger within said cabin.
An emergency oxygen breathing device is known from the European patent
application
EP 2 143 469 Al. According to this reference, an oxygen breathing device
provides
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oxygen flow from an oxygen source to an oxygen mask of a passenger or crew
member.
The oxygen flow is controlled by a control unit to ensure that the passenger
is supplied
with an exact amount of oxygen. The control unit receives pressure signals
corresponding
to the ambient pressure from a pressure sensor and temperature signals
corresponding
to the oxygen temperature passing through the breathing device from a
temperature
sensor. Generally, with such a device, it is possible to supply an amount of
oxygen to a
passenger in an emergency case which ensures that the passenger receives
enough
oxygen for maintaining all vital functions.
One important aspect of such oxygen breathing devices, however, is the desire
to reduce
the weight and the size of such devices in order to reduce the overall weight
of the aircraft
and to provide additional space for entertainment systems or the like. This
size and
weight reduction, however, shall not effect a reduction of the time period of
supply of
oxygen to a passenger. Accordingly, it is an object of the invention to
provide an emer-
gency oxygen system for passengers of an aircraft with reduced size and
weight.
A further aspect of existing known assistance systems is the need to
periodically maintain
these systems and to adapt them to enhanced requirements or regulations in the
aircraft
industry. In the course of such maintenance it is a desire to be able to
improve existing
known oxygen systems in order to save weight and or space or to improve the
characte-
ristics of such systems in order to adapt them to existing requirements or
regulations. It is
a further object of the invention to provide a method and device which allows
improve-
ment of existing maintenance procedures in an efficient way.
It is another object to install modern oxygen masks which provide for low
oxygen con-
sumption at heights between 15.000 and 30.000 feet. Therefore, the oxygen flow
at these
heights needs to be adapted accordingly.
These and other objects are achieved by an oxygen breathing device according
to the
introductory function having an oxygen source, in particular a chemical oxygen
generator
or an oxygen pressure tank, at least one oxygen mask connected via an oxygen
supply
line to said oxygen source, a flow control unit adapted to receive a signal
indicating
ambient pressure or to detect ambient pressure and to control the flow of
oxygen through
the oxygen supply line depending on said ambient pressure, wherein the flow
control unit
is adapted to provide a low oxygen flow at a first ambient pressure, provide a
higher
oxygen flow at a second ambient pressure which is lower than said first
ambient pressure
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and to increase said oxygen flow in at least two steps, preferably to increase
said oxygen
flow constantly, wherein a bypass valve is arranged in the oxygen supply line
and com-
prises a first flow path and a second flow path comprising a bypass channel in
a parallel
flow arrangement to said first flow path, wherein said bypass valve is adapted
to direct
the flow of oxygen through said first flow path at an ambient pressure above a
predeter-
mined level according to a first flow condition and direct the flow of oxygen
through said
second flow path at an ambient pressure below a predetermined level according
to a
second flow condition, wherein said first flow path has a smaller flow cross
section than
said second flow path.
o The oxygen breathing device provides for a weight saving means for life
support of pas-
sengers in an aircraft. The device can be integrated in existing oxygen
breathing systems
without the need to redesign such existing systems. Moreover, the oxygen
breathing
device according to the invention is adapted to be used for currently used
oxygen masks
providing reduced oxygen consumption. Thereby, a reduced overall system weight
can
be achieved.
Preferably, the first ambient pressure is a system pressure corresponding to
an altitude of
the aircraft below 30.000 feet, e.g. intermediate altitudes between 15.000 and
30.000
feet. Still further it is preferred that the second ambient pressure is a
system pressure
corresponding to an altitude of the aircraft above 30.000 feet. The term
smaller flow cross
zo section reflects the fact that a smaller amount of oxygen per unit time
can flow through
the first flow path compared to the second flow path.
According to a first preferred embodiment, said first flow path comprises a
calibrated
orifice. Thereby, a predetermined maximum amount of oxygen flow to the
passenger can
be achieved. Preferably, the calibrated orifice can be a channel with a
predetermined
cross section which is arranged in the first flow path in a way that oxygen
flowing through
the first flow path has to flow through the calibrated orifice. Depending on
the size of the
cross section the maximum oxygen flow to a passenger or crew member can be ad-
justed.
If the amount of oxygen entering the bypass valve exceeds the amount of oxygen
leaving
the bypass valve at the outlet due to the calibrated orifice, the pressure in
the oxygen
supply line increases. This pressure increase can be utilized as a signaling
condition for
the bypass valve to switch to the second flow condition.
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According to a further embodiment said first flow path consists of a flow
through a cali-
brated orifice only and said second flow path consists of a flow through said
bypass
channel only or said bypass channel and said calibrated orifice. This provides
for a flexi-
ble and reliable embodiment of oxygen supply to the passenger.
A further preferred embodiment is characterized in that said bypass valve
comprises a
first flow channel comprising an orifice with a predetermined cross-section
and a second
flow channel, wherein a spring biased valve member engages a valve seat and a
pres-
sure inside the oxygen supply line acting against said spring to switch the
valve member
to switch the bypass valve between said first and second flow condition. This
provides for
an automatic and pressure controlled way of switching the bypass valve between
the first
and second flow condition.
The spring biased valve member preferably comprises an adjustable spring
comprising
an adjustment screw which can be mounted in a housing of the bypass valve. By
adjust-
ing the screw, the load of the spring and, accordingly, the pressure inside
the oxygen
supply line which is sufficient for lifting the valve member can be adjusted.
In another preferred embodiment a plurality of oxygen masks are connected to
said
oxygen source via a manifold, the oxygen supply line comprises a first central
oxygen line
section directing oxygen from the oxygen source to said manifold and a
plurality of
second oxygen line sections each directing oxygen from the manifold to an
oxygen mask,
zo said bypass valve is arranged in flow direction between said flow
control unit and said
oxygen masks. This provides for a central supply of oxygen from the oxygen
source to
the plurality of oxygen masks.
In another embodiment said bypass valve is arranged in said first central
oxygen line
section, in particular in flow direction between said flow control unit and
said manifold.
This provides for further weight saving, since a centralized bypass valve is
provided for a
plurality of oxygen masks, i.e. for the oxygen supply of a plurality of
passengers.
A further embodiment of the aforementioned oxygen breathing device comprises a
plu-
rality of bypass valves, wherein at least a number of said plurality of second
oxygen line
sections comprises one of said plurality of bypass valves. Thereby, a
decentralized
arrangement of the bypass valves is achieved which provides for an increased
liability of
the oxygen breathing device. If one of the bypass valves does not function
sufficiently,
which would lead to a malfunction of the oxygen supply to one of the oxygen
masks, the
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other remaining oxygen masks will still work sufficiently. In such an
emergency case two
passengers are able to share one oxygen mask.
According to a further embodiment of the oxygen breathing device, said bypass
valve
comprises a first and a second calibrated orifice, said second calibrated
orifice having a
larger flow cross section than said first calibrated orifice, wherein in said
first flow condi-
tion the oxygen is flowing through said first calibrated orifice and in said
second flow
condition the oxygen is at least partially circumventing said first calibrated
orifice and is
flowing through said second calibrated orifice. This provides for a
predetermined maxi-
mum oxygen flow in the second flow condition. Thereby, the oxygen flow to the
passen-
ger breathing mask can be calibrated both for the first and second flow
condition. Hence,
there is no need for a further calibrated orifice arranged in the passenger
breathing mask.
According to a further embodiment of the breathing device, in said second flow
condition
a first part of the oxygen is flowing through said first calibrated orifice
and a second part
of the oxygen is flowing through a bypass channel arranged in parallel to said
first calk
brated orifice.
According to another embodiment, in said first flow condition the oxygen is
flowing
through said first and second calibrated orifice in a serial arrangement. This
provides for
a space saving design of the bypass valve with a simplified design.
In another embodiment of the oxygen breathing device said bypass valve
comprises a
housing having an inlet opening and an outlet opening, a first flow channel
connecting
said inlet opening and said outlet opening, a second flow channel connecting
said inlet
opening and said outlet opening a valve piston sealing against a valve seat
inside said
housing, wherein, when said valve piston is in sealing contact to said valve
seat, the
second flow channel is interrupted thus requiring oxygen flowing through the
bypass
valve from the inlet to the outlet opening to flow through said first flow
channel, and
wherein, when said valve piston is in a distance position without contact to
said valve
seat, the second flow channel is open thus allowing oxygen flowing through the
bypass
valve from the inlet to the outlet opening to flow through said first and said
second flow
channel. Thereby, a reliable bypass valve with a simple design is achieved.
According to another embodiment of the aforementioned oxygen breathing device,
a first
calibrated orifice is arranged in the first flow channel and a second
calibrated orifice is
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arranged in the second flow channel, wherein said first calibrated orifice has
a smaller
flow cross section than said second calibrated orifice. This provides for a
oxygen flow to
the passenger in the second flow condition which is greater than the oxygen
flow to the
passenger in the first flow condition.
According to a further embodiment of the aforementioned oxygen breathing
device, said
piston is hollow, the first and second flow channel extend through said piston
and said
second calibrated orifice is arranged in the piston. Thereby, a space saving
design of the
bypass valve is achieved.
A further aspect of the invention is a method for providing oxygen to a
passenger of an
aircraft, comprising the steps of:
- providing oxygen from an oxygen source to at least one oxygen mask,
- automatically controlling the oxygen by a flow control unit by
0 receiving a
signal indicating ambient pressure or detecting ambient pres-
sure and
0 controlling the flow of oxygen through the oxygen supply line depending
on said ambient pressure, in that a low oxygen flow is provided at a first
ambient pressure, and a higher oxygen flow is provided at a second am-
bient pressure which is lower than said first ambient pressure
o whereby said
oxygen flow is increased in at least two steps, preferably
constantly,
characterized in that
- the oxygen is directed from said flow control unit to said oxygen mask via a
bypass
valve comprising a first flow path and a second flow path comprising a bypass
channel in a parallel flow arrangement to said first flow path,
- switching said bypass valve to
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o direct the flow of oxygen through said first flow path at an ambient pres-
sure above a predetermined level according to a first flow condition and
o direct the flow of oxygen through said second flow path at an ambient
pressure below a predetermined level according to a second flow condi-
tion,
o wherein said first flow path has a smaller flow cross section than said
second flow path.
Another aspect of the invention is a method for maintaining an emergency
oxygen system
of an aircraft, said emergency oxygen system comprising:
- an oxygen source, in particular a chemical oxygen generator or an oxygen
pressure tank,
- at least one oxygen mask connected via an oxygen supply line to said oxygen
source,
- a flow control unit adapted to receive a signal indicating ambient pressure
or to
detect ambient pressure and to control the flow of oxygen through the oxygen
supply line depending on said ambient pressure, wherein the flow control unit
is
adapted to
o provide a low oxygen flow at a first ambient pressure,
o provide a higher oxygen flow at a second ambient pressure which is low-
er than said first ambient pressure and
o to increase said oxygen flow in at least two steps, preferably to
increase
said oxygen flow constantly,
characterized by the steps of
installing a bypass valve in said oxygen supply line, said bypass valve
compris-
ing a first flow path and a second flow path comprising a bypass channel in a
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parallel flow arrangement to said first flow path, wherein said bypass valve
is
adapted to
o direct the flow of oxygen through said first flow path at an ambient
pressure above a predetermined level according to a first flow condi-
tion and
o direct the flow of oxygen through said second flow path at an ambient
pressure below a predetermined level according to a second flow con-
dition,
o wherein said first flow path has a smaller flow cross section than said
second flow path.
Preferred embodiments of the invention are described in connection with the
figures,
wherein
Fig. 1 is a first embodiment of a bypass valve in a side view according to the
present
invention,
Fig. 2 is a second embodiment of a bypass valve in a side view according to
the present
invention,
Fig. 3 is a first embodiment of an oxygen breathing device in a schematic view
according
to the present invention,
Fig. 4 is a second embodiment of an oxygen breathing device in a schematic
view ac-
cording to the present invention and
Fig. 5 is a third embodiment of an oxygen breathing device in a schematic view
according
to the present invention.
Figure 1 shows a bypass valve 1 arranged in an oxygen supply line 2 comprising
a first
flow path 3 and a second flow path 4. The bypass valve 1 can preferably be
positioned in
oxygen flow direction close to a passenger oxygen mask not shown in Fig. 1.
The second
flow path 4 comprises a bypass channel 5 in a parallel flow arrangement to the
first flow
path 3. The bypass valve 1 is adapted to direct a flow of oxygen 6 through
said first flow
path 3 at an ambient pressure above a predetermined level, according to a
first flow
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condition, i.e. a system pressure corresponding to an altitude of the aircraft
below 30.000
feet. Therefore, at intermediate altitudes, e.g. 15.000-30.000 feet, the
second flow path 4
of the bypass valve 1 is closed.
Furthermore, the bypass valve 1 is adapted to direct the flow of oxygen 6
through said
second flow path 4 at an ambient pressure below a predetermined level
according to a
second flow condition, i.e. a system pressure corresponding to an altitude of
the aircraft
above 30.000 feet. The first flow path 3 comprises a calibrated orifice 7
which has a
smaller flow cross section than the second flow path 4 when it is open. At
intermediate
altitudes, the calibrated orifice 7 reduces the effective flow of oxygen to
the passenger
io mask.
The bypass valve 1 comprises a first flow channel 10 which serves as the first
flow path
3. The second flow path 4 consists of a second flow channel 11, wherein a
spring biased
valve member 12 contacts a valve seat 13 when the second flow path 4 is
closed. A
pressure inside the oxygen supply line 2 acts against a spring 14 to engage
the valve
member 12 to switch the bypass valve 1 between a first and second flow
condition. I.e.
the orifice 7 is calibrated in a way that at a predetermined inlet pressure,
the valve mem-
ber 12 will be lifted against the force of the spring 14. Thereby, the second
flow path 4 is
opened.
The load of the spring 14 can be adjusted by an adjustment screw 15 which is
mounted in
zo a housing 20 of the bypass valve 1. In an alternative embodiment of the
bypass valve 1,
the design of the valve member 12 can also be realized by a membrane
arrangement.
The second flow channel 11 comprises a calibrated orifice 21 with a cross
section which
is greater than the cross section of the calibrated orifice 7.
Figure 2 shows a bypass valve 30 arranged in an oxygen supply line 31
comprising a first
flow channel 32 and a second flow channel 33. The second flow channel 33
comprises
two bypass channels 34 and 35 in a parallel flow arrangement to the first flow
channel 32.
The bypass valve 30 is adapted to direct a flow of oxygen 36 through said
first flow chan-
nel 32 at an ambient pressure above a predetermined level, i.e. a system
pressure cor-
responding to an altitude of the aircraft below 30.000 feet.
The first flow channel 32 comprises a calibrated orifice 37 which provides for
a certain
flow of oxygen at a certain pressure in an inlet 42 of the bypass valve 30.
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In flow direction behind the calibrated orifice 37 the bypass valve 30
comprises a piston
40 with a valve seat 41 which is closed when the oxygen pressure in the inlet
42 of the
bypass valve is lower than a predetermined pressure value. The piston 40 will
be lifted
against a force of a spring 43 when the inlet pressure exceeds the
predetermined value.
The load of the spring 43 can be adjusted by an adjustment screw not shown in
Fig. 2
which is mounted in a housing 47 of the bypass valve 30. Then oxygen flows
through the
first flow channel 32 and, additionally, through the second flow channel 33,
i.e. through
the bypass channels 34 and 35. Thereby, an increased oxygen flow 45 is
achieved at an
outlet 46 of the bypass valve 30 adapted to direct the oxygen flow 45 to a
passenger
o oxygen mask not shown in Fig. 2.
The piston 40 is a hollow and a second calibrated orifice 46 is arranged in
the piston 40 in
oxygen flow direction behind the first and second flow channel 33. The bypass
valve 30 is
encapsulated by the housing 47 comprising an inlet opening 48 and an outlet
opening 49.
Oxygen flowing from the inlet opening 48 to the outlet opening 49 passes
through orifice
37 and further through orifice 46 in a first flow condition. The orifice 46
has a greater
cross section than orifice 37. In a second flow condition, oxygen flowing from
the inlet
opening 48 to the outlet opening 49 passes through the orifice 37,
additionally through
the channels 34 and 35 and then through the orifice 46.
Figure 3 shows a first embodiment of an oxygen breathing device 50 in a
schematic view
comprising an oxygen source 51. The oxygen source 51 can be a high pressure
gaseous
oxygen or chemical oxygen source. The pressurized oxygen supplied by the
oxygen
source 51 enters a flow control unit 52 including a regulation valve. The flow
control unit
52 controls the outlet pressure of the oxygen flow to be supplied to a bypass
valve 53
arranged in flow direction behind the flow control unit 52. The flow control
depends on the
altitude of the aircraft, i.e. the flow control unit 52 receives a signal
indicating ambient
pressure and controls the oxygen flow accordingly. Preferably, the outlet
pressure of the
flow control unit 52 is a suitable system and/or breathing pressure. With
increased alti-
tude the flow control unit 52 increases the oxygen pressure to be supplied to
the bypass
valve 53. The bypass valve 53 can be a bypass valve substantially equal to the
bypass
valve as described in Figure 1.
The oxygen breathing device 50 further comprises a distribution network with
manifolds
54 for distributing the oxygen flow to a number of passenger oxygen masks 55.
Cali-
brated orifices 56 are arranged close to the oxygen passenger masks 55 in
oxygen flow
direction close to each oxygen mask 55. The oxygen source 51, the flow control
unit 52,
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the bypass valve 53 and the oxygen masks 55 are connected via an oxygen supply
line
57. The oxygen supply line 51 includes a first central oxygen line section 58
directing
oxygen from the oxygen source 51 to the manifold 54 and a plurality of second
oxygen
line sections 59 each directing oxygen from the manifold 54 to an oxygen mask
55.
Fig. 4 shows a second embodiment of an oxygen breathing device 60 similar to
the
oxygen breathing device 50 as shown in Fig. 3. The oxygen breathing device 60
com-
prises an oxygen source 51, a flow control unit 52 and a number of
decentralized bypass
valves 61 arranged in a distribution network 62 comprising manifolds 63. The
bypass
valves 61 are supplied with oxygen via an oxygen supply line 64 including a
first central
io oxygen line section 65 and a number of second oxygen line sections 66.
The dimensions
of the bypass valves 61 are smaller than the dimensions of the bypass valve 53
shown in
Fig. 3.
Fig. 5 shows a third embodiment of an oxygen breathing device 70 similar to
the oxygen
breathing device 60 as shown in Fig. 4. The oxygen breathing device 70
comprises an
oxygen source 51, a flow control unit 52 and a plurality of combined bypass
valves 71,
similar to the bypass valve 30 as depicted in Fig. 2. The combined bypass
valves 71 are
arranged in oxygen flow direction close to each passenger oxygen supply mask
72.
Calibrated orifices 73 for controlling the oxygen flow to the passenger are
each integrated
in one of the combined bypass valves 71. The dimensions of the bypass valves
71 are
zo smaller than the dimensions of the bypass valves 53 shown in Fig. 3 and
bypass valves
61 shown in Fig. 4.
