METHOD FOR PROTECTING AIRCRAFT OCCUPANT AND BREATHING MASK

1 . Method for protecting aircraft occupant comprising the steps of:

providing a user with a breathing mask for aircraft occupant,

providing a respiratory gas including a mixture of breathable gas and dilution gas to the user,

sensing partial pressure or rate of oxygen in respiratory gas,

adjusting the rate (fraction/percentage/concentration) of oxygen (or breathable gas) in the respiratory gas, further comprising:

sensing partial pressure or rate of oxygen in the exhalation gas generated by the user,

determining coherence between the partial pressure or rate of oxygen sensed in the exhalation gas and the partial pressure or rate of oxygen in respiratory gas sensed for detecting failure.

2 . The method according to claim 1 , comprising:

adjusting the rate of oxygen in the respiratory gas in accordance with the partial pressure or rate of oxygen or carbon dioxide in the exhalation gas.

3 . The method according to claim 1 , comprising:

sensing partial pressure or rate of oxygen in exhalation gas generated by the user,

adjusting the rate of oxygen in the respiratory flow in accordance with the partial pressure or rate of oxygen in exhalation gas.

4 . The method according to claim 3 , comprising:

sensing partial pressure or rate of oxygen and carbon dioxide in exhalation Gas generated by the user,

adjusting the rate of oxygen in the respiratory flow in accordance with the partial pressure or rate of oxygen and carbon dioxide in exhalation gas.

5 . (canceled)

6 . The method according to claim 1 further comprising:

sensing barometric pressure in the aircraft and

determining coherence between the partial pressure or rate of oxygen sensed in the exhalation gas and the partial pressure or rate of oxygen in respiratory gas thanks to a coherence equation including:

the partial pressure or rate of oxygen sensed in the exhalation gas,

the partial pressure or rate of oxygen in respiratory gas, and

the barometric pressure.

7 . The method according to claim 6 wherein said coherence equation is:

P A O 2 =F 1 O 2 .(P B −P A H 2 O)−P A CO 2 .(F 1 O 2 +(1−F 1 O 2 )/R),

with

P A O 2 is the oxygen partial pressure sensed in the exhalation gas

P B is the barometric pressure in the aircraft

P A CO 2 is the partial pressure of carbon dioxide in the exhalation gas

P A H 2 O is the partial pressure of water in the exhalation gas

F 1 O 2 is rate of oxygen or the partial pressure of oxygen sensed in the respiratory gas (62)

R is a constant between 0.1 and 1.2 corresponding to respiratory quotient.

8 . The method according to claim 7 further comprising:

sensing the partial pressure of carbon dioxide in the exhalation gas.

9 . The method according to claim 7 wherein the partial pressure of water in the exhalation gas is replaced by a constant.

10 . The method according to claim 1 wherein the coherence is determined by comparison of a range value and a ratio between the measured value and the value estimated by the coherence equation.

11 . The method according to claim 1 further comprising sensing the partial pressure or rate of oxygen in the exhalation gas and the partial pressure or rate of oxygen in respiratory gas sensed with a sole (the same) gas sensor.

12 . A breathing mask for aircraft occupant including a demand regulator, said regulator comprising:

a breathable gas supply line to be connected to a source of breathable gas and supplying a flow chamber with breathable gas,

dilution gas supply line to be connected to a source of dilution gas and supplying the flow chamber with dilution gas,

a dilution adjusting device adjusting the rate of dilution gas in the respiratory gas supplied to the flow chamber, the dilution adjusting device comprising a dilution valve, a gas sensor adapted to sense partial pressure or rate of oxygen or carbon dioxide and a control device controlling the dilution valve in accordance with a dilution signal generated by the gas sensor in function of the partial pressure or rate of oxygen or carbon dioxide, wherein:

the dilution adjusting device further comprises a gas flow direction sensor,

the control device comprises a pump electrochemical cell placed in the flow chamber for alternatively sensed the oxygen partial pressure in the respiratory gas and in the exhalation gas.

13 . The breathing mask according to claim 12 wherein the gas sensor is adapted to sense partial pressure or rate of oxygen or carbon dioxide in exhalation gas generated by the user.

14 . The breathing mask according to claim 12 wherein the gas sensor is adapted to sense partial pressure or rate of oxygen.

15 . The breathing mask according to claim 14 wherein the dilution adjusting device further comprises a carbon dioxide gas sensor.

16 . (canceled)

17 . (canceled)