Breathing apparatus for an aircrew member
The invention relates to a breathing apparatus for providing a respiratory gas to a crewmember in a cabin of an aircraft, said breathable apparatus comprising an air inlet ( 5 ) for admission of ambient air in said breathing apparatus, an additional gas inlet ( 2 ) for admission of additional gas in said breathing apparatus, an outlet nozzle ( 4 ) for feeding said crew member with the respiratory gas comprising said ambient air and/or additional gas, said breathing apparatus further comprising neutralizing means ( 70, 141 ) for neutralizing at least partially the admission of said additional gas below a predefined cabin altitude (Z 1 ).
1. A breathing apparatus for providing a respiratory gas to a crewmember in a cabin of an aircraft, said breathing apparatus comprising:
an air inlet for admission of ambient air in said breathing apparatus,
an additional gas inlet for admission of additional gas in said breathing apparatus,
mixing chamber for mixing the ambient air with the additional gas,
an outlet nozzle for feeding said crew member with the respiratory gas comprising said ambient air and/or additional gas,
a neutralizing device for neutralizing the admission of said additional gas below a predefined cabin altitude (Z 1 ), the neutralizing device comprising:
an air circuit for feeding said mixing chamber with ambient air, the pressure loss of said air circuit depending upon cabin altitude,
a sealing element movable between a first position wherein the pressure loss of the air circuit is minimal and a second position wherein the pressure loss of said air circuit is increased, said sealing element being in its first position when the cabin altitude is below the predefined cabin altitude, and said sealing element being in its second position when the cabin altitude is greater than the predefined cabin altitude,
a first altimetric device adapted to move the sealing element into its second position when the cabin altitude is greater than the predefined altitude, and
a second altimetric device provided to pilot entry of ambient air into said apparatus as a function of the cabin altitude when the sealing element is in its second position.
2. A breathing apparatus according to claim 1 , wherein the neutralizing device further neutralizes at least partially the admission of ambient air when the cabin altitude is greater than the predefined cabin altitude.
3. A breathing apparatus according to claim 1 , wherein the air circuit is characterized by a flow area depending upon the cabin altitude.
4. A breathing apparatus according to claim 1 , wherein the first position of the sealing element is a resting position.
5. A breathing apparatus according to claim 1 , wherein the first altimetric device is an altimetric capsule.
6. A breathing apparatus according to claim 1 , wherein the first altimetric device comprises a piston.
7. A breathing apparatus according to claim 1 , wherein the neutralizing device further comprises non return device to maintain the sealing element in its second position even when the cabin altitude decreases and goes below the predefined cabin altitude.
8. A breathing apparatus according to claim 1 , wherein the first altimetric device comprises a piston chamber and a remotely controlled valve, said remotely controlled valve driving the piston chamber pressure between a first and a second value, the sealing element being movable in response to the pressure in said piston chamber.
9. A breathing apparatus according to claim 1 , wherein the second altimetric device is carried by the sealing element.
10. A breathing apparatus according to claim 1 , wherein the air circuit further comprises a second air inlet and a second feed pipe, the sealing element closing said second air feed pipe in its second position.
11. A breathing apparatus for providing a respiratory gas to a crewmember in a cabin of an aircraft, said breathing apparatus comprising:
an air inlet for admission of ambient air in said breathing apparatus,
an additional gas inlet for admission of additional gas in said breathing apparatus,
mixing chamber for mixing the ambient air with the additional gas,
an outlet nozzle for feeding said crew member with the respiratory gas comprising said ambient air and/or additional gas,
a neutralizing device for neutralizing the admission of said additional gas below a predefined cabin altitude (Z 1 ), the neutralizing device comprising:
an air circuit for feeding said mixing chamber with ambient air, the pressure loss of said air circuit depending upon the cabin altitude,
a sealing element movable between a first position wherein the pressure loss of the air circuit is minimal and a second position wherein the pressure loss of said air circuit is increased, said sealing element being in its first position when the cabin altitude is below the predefined cabin altitude, and said sealing element being in its second position when the cabin altitude is greater than the predefined altitude,
wherein the air circuit comprises the air inlet, an air feed pipe, a second air inlet, and a second feed pipe, with the sealing element closing said second air feed pipe when the sealing element is in its second position.
12. A breathing apparatus according to claim 11 , wherein the neutralizing device further comprises a device provided to pilot the entry of ambient air into said apparatus as a function of the cabin altitude when the sealing element is in its second position.
13. A breathing apparatus according to claim 11 , wherein the neutralizing device further comprises
a first altimetric device adapted to move the sealing element into its second position when the cabin altitude is greater than the predefined altitude, and
a second altimetric device provided to pilot entry of ambient air into said apparatus as a function of the cabin altitude when the sealing element is in its second position.
14. A breathing apparatus according to claim 13 , wherein the first altimetric device is an altimetric capsule.
15. A breathing apparatus for providing a respiratory gas to a crewmember in a cabin of an aircraft, said breathing apparatus comprising:
an air inlet for admission of ambient air in said breathing apparatus,
an additional gas inlet for admission of additional gas in said breathing apparatus,
a mixing chamber for mixing the ambient air with the additional gas,
an outlet nozzle for feeding said crew member with the respiratory gas comprising said ambient air and/or additional gas,
a neutralizing device for neutralizing the admission of said additional gas below a predefined cabin altitude (Z 1 ), the neutralizing device comprising:
an air circuit for feeding said mixing chamber with ambient air, the pressure loss of said air circuit depending upon the cabin altitude,
a sealing element movable between a first position wherein the pressure loss of the air circuit is minimal and a second position wherein the pressure loss of said air circuit is increased, said sealing element being in its first position when the cabin altitude is below the predefined cabin altitude, and said sealing element being in its second position when the cabin altitude is greater than the predefined altitude, and
a non return device to maintain the sealing element in its second position even when the cabin altitude decreases and goes below the predefined cabin altitude.