Respiration system with adjustable oxygen ratio, in particular for spacecrafts
By designing a dilution system for spacecraft, using feedback loops to adjust the oxygen ratio in the gas mixture, the problem of inaccurate oxygen ratio control in the prior art is solved, and the safety of crew members and the autonomy of the spacecraft are improved.
Patent Information
- Application Number
- CN202380056392.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-07-27
- Filing Date
- 2023-07-17
- Publication Date
- 2025-03-11
AI Technical Summary
The prior art is difficult to accurately and reliably control the proportion of oxygen received by spacecraft crew members, resulting in insufficient or excessive consumption of oxygen, affecting the safety of the crew and the autonomy of the spacecraft.
A dilution system is designed, including a gas mixture inlet, a dilution gas inlet, a sensor and a control system, to adjust the oxygen ratio in the gas mixture through a feedback loop to ensure it is close to the set value and adapt to different breathing conditions and occupant states.
Accurate control of the oxygen ratio is achieved, the problems of insufficient or excessive consumption of oxygen are avoided, and the safety of crew members and the autonomy of the spacecraft are improved.
Smart Images
Figure CN119604339A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to regulating the proportion of oxygen delivered by a breathing system to an occupant of a spacecraft.
[0002] More particularly, the invention relates to a breathing system, in particular for a spacecraft, and a method for controlling such a system. Background Art
[0003] A gas mixture containing oxygen is delivered to the occupants of the spacecraft via a mask connected to a source of breathable gas. Such a source of breathable gas may be a gas mixture, which may contain oxygen or air highly enriched with oxygen, stored in one or more cylinders or in a pressurized oxygen reserve arranged on board the spacecraft.
[0004] The oxygen supply may be replaced by an on-board oxygen generating system, for example one or more on-board oxygen generating systems (also referred to by the acronym OBOGS) supplied with air by the compressor of one or more engines.
[0005] The onboard oxygen generating system may also comprise a molecular sieve oxygen generating system (also referred to by the acronym MSOGS) arranged to provide oxygen enriched air at a desired oxygen concentration by adsorbing nitrogen from air supplied to the system.
[0006] This distribution is intended to protect the occupants from hypoxia, for example in the event of a decompression of the spacecraft cabin, in particular from the presence of smoke and / or vapors in the spacecraft cabin in the event of an accident, or from the effects of acceleration in the case of military spacecraft.
[0007] The gas mixture may also include a diluent gas, such as ambient air or air from a compressed air source.
[0008] Controlling the oxygen ratio in the gas mixture is crucial, especially to avoid delivering too little oxygen for effective operation. In fact, insufficient oxygen consumption can create safety problems, as the crew is not properly protected against hypoxia. This is even more harmful when the crew is a spacecraft pilot, and the risk of error increases, as hypoxia can cause the pilot to lose consciousness.
[0009] Conversely, excessive oxygen consumption depletes oxygen reserves. This reduces the autonomy of oxygen distribution. This is even more harmful when the occupant is a spacecraft pilot, especially a military spacecraft pilot, and the risk of error increases, since the reduced autonomy of oxygen distribution may lead to the necessity to shorten the flight time.
[0010] Furthermore, the proportion of oxygen required is likely to vary depending on the conditions and the occupants (depending on the criticality of the role they perform).
[0011] Oxygen masks can function by using dilution as needed: diluent gas and oxygen are injected when the occupant wearing the mask breathes in. Inhalation is detected when negative pressure is present in the mask, specifically by a differential pressure sensor or relative pressure sensor for electronically controlled management of the oxygen ratio, or by a membrane for mechanical control of the oxygen ratio.
[0012] Typically, dilution occurs continuously; the diluent gas and oxygen are simultaneously injected into the mask where they are consumed.
[0013] A common solution for this is to inject oxygen under pressure via a venturi placed in a capsule. The capsule volume can be connected to the outside so that the acceleration of the oxygen in the venturi creates a negative pressure that draws in a diluent gas mixed with it, such as ambient air.
[0014] This technology is purely mechanical. The dilution level is therefore ensured by the geometry of the Venturi tube and by an altimeter capsule which reduces the passage of dilution gas as the altitude increases, thus increasing the proportion of oxygen as the altitude increases.
[0015] In this device, the dilution of the oxygen / dilution gas mixture supplied to the occupant wearing the mask is a function of the altitude. To achieve this, the dilution gas is carried by the Venturi effect generated by an injector with a variable cross section, fed by the oxygen flow generated by the opening of the main valve. The dilution is adjusted as a function of the altitude by means of a capsule (for example an aneroid capsule), which blocks the dilution gas inlet and thus increases the oxygen supply ratio.
[0016] A variant consists in controlling the dilution electronically. Thus, as described in documents EP 2 010 296 and EP 1 765 444, a pressure sensor placed at the neck of the venturi is used to measure the flow rate of the injected air. This measurement, coupled with knowledge of the air pressure, makes it possible to calculate the oxygen flow rate required to achieve the desired oxygen ratio. This oxygen flow rate is then obtained by adjusting the oxygen pressure upstream of the calibrated orifice via an electronically controlled valve.
[0017] Furthermore, it is known to carry out separate injections of oxygen and dilution air, which are developed in the stage-dilution technique. Thus, during the same inhalation cycle, pure oxygen is continuously injected and then dilution air is injected to supplement the inhalation.
[0018] Furthermore, a combined oxygen / air valve is known, in particular from document FR 2 334 374, for injecting oxygen and dilution air separately, with one blocking the other and vice versa. This technique makes it possible to reposition the regulator, but it requires measuring the duration of the inspiration. In practice, the combined oxygen / air valve is controlled based on the opening time, which is an indicator of the duration of the inspiration.
[0019] However, such systems do not allow very precise control of the proportion of oxygen in the gas mixture actually delivered to the occupant wearing the mask. This lack of precision makes it impossible to take into account drift in the system, which can lead to serious consequences, especially when the amount of oxygen delivered is overestimated.
[0020] Furthermore, these systems do not take into account that at the end of inspiration some oxygen is lost as "dead volume" which does not enter the lungs but remains in the trachea where it is not used by the body. Summary of the invention
[0021] The present invention aims to remedy the above-mentioned drawbacks by proposing a dilution system which allows precise and reliable control of the proportion of oxygen delivered to the user or occupant.
[0022] To this end, the present invention relates to a breathing system, in particular for a spacecraft, comprising:
[0023] - a distribution member adapted to deliver the gas mixture to at least one occupant,
[0024] a gas mixture inlet connectable to a source of breathable gas, said gas mixture inlet comprising a gas mixture inlet valve intended to adjust the proportion of breathable gas in the gas mixture,
[0025] a dilution gas inlet connectable to a dilution gas source, said dilution gas inlet comprising a dilution gas inlet valve intended to adjust the proportion of dilution gas in the gas mixture,
[0026] - at least one sensor adapted to measure information representative of the proportion of breathable gas in the gas mixture delivered by said distribution member, and
[0027] - a control system configured to adjust the ratio of breathable gas delivered according to the measured information and to control the gas mixture inlet valve and the dilution gas inlet valve according to the ratio of breathable gas delivered and the ratio of breathable gas desired.
[0028] This system makes it possible to implement a feedback loop for adjusting the proportion of breathable gas delivered to be as close as possible to a set value and to maintain said set value despite possible changes in breathing conditions and / or breathing patterns of the occupant.
[0029] The breathable gas may be, for example, pressurized oxygen from a storage cylinder. Furthermore, the diluent gas may be, for example, ambient air.
[0030] The dispensing member may in particular comprise a mask intended to be worn on the face of an occupant acting as mask wearer, and a tube adapted to allow the circulation of the gas mixture and / or the breathable gas.
[0031] The dilution gas inlet valve is specifically an "all or nothing" type valve.
[0032] The information indicative of the proportion of breathable gas may be a measurement of the volume fraction and / or mass fraction of breathable gas, a ratio of flow rates in a gas mixture inlet valve and / or a dilution gas inlet valve, a blood gas level of breathable gas in a mask-wearing occupant, or other information.
[0033] The sensor may comprise a first flow meter adapted to measure the flow rate of breathable gas through the gas mixture inlet valve, and / or a second flow meter adapted to measure the flow rate of dilution gas through the dilution gas inlet valve, and / or an oxygen sensor, and / or a physiological sensor.
[0034] The flow meters used can be from various technologies: thermal (hot wire probe type), acoustic (Doppler effect type) or mechanical (cantilever or Coriolis effect type) or based on pressure measurement (laminar flow, orifice plate, Venturi tube, etc.).
[0035] Alternatively, at least one of the sensors may include an oxygen sensor and / or a physiological sensor.
[0036] The dispenser part may comprise a mask and means for detecting the inhalation phase, in particular a pressure sensor particularly suitable for measuring the pressure in the interior space of the mask.
[0037] This feature makes it possible to obtain information about the breathing cycle of the occupant wearing the mask.
[0038] The control system may be configured to detect inhalation by the occupant and to vary the flow rate and / or volume through the gas mixture inlet valve and / or through the dilution gas inlet valve during the course of a breathing cycle.
[0039] This feature makes it possible to implement the dilution in stages and to adjust the dilution according to the breathing rate of the mask wearer.
[0040] The control system may be configured to control the gas mixture inlet valve and the dilution gas inlet valve to deliver:
[0041] a gas mixture during at least an initial phase of a breathing cycle, the gas mixture comprising, for example, at least 60% of breathable gas, in particular at least 75% of breathable gas, and more particularly at least 90% of breathable gas, and
[0042] - a gas mixture during at least one final phase of a breathing cycle, the gas mixture comprising, for example, at least 60% of diluent gas, in particular at least 75% of diluent gas, and more particularly at least 90% of diluent gas.
[0043] During a single breathing cycle, the initial phase occurs before the final phase.
[0044] This feature makes it possible to avoid the loss of breathable gas into respiratory dead volume that does not reach the lungs.
[0045] The control system may be configured to calculate an average proportion of breathable gas delivered during a breathing cycle and to adjust flow rates through the gas mixture inlet valve and the dilution gas inlet valve during a subsequent inhalation based on the average proportion of breathable gas.
[0046] This feature allows the flow rate to be adjusted so that the proportion of breathable gas in the delivered mixture more closely matches the desired proportion of breathable gas.
[0047] The control system can be configured to repeatedly measure the flow rate through the gas mixture inlet valve and / or through the dilution gas inlet valve during a breathing cycle, and control the gas mixture inlet valve and the dilution gas inlet valve based on the ratio of breathable gas delivered and the ratio of breathable gas desired.
[0048] This feature allows the ratio of breathable gas delivered to converge toward a desired ratio more quickly.
[0049] The control system can be configured to control the gas mixture inlet valve and / or the dilution gas inlet valve to deliver a gas mixture including both breathable gas and dilution gas during an intermediate phase of the breathing cycle, with one of the gas mixture inlet valve and / or the dilution gas inlet valve operating at a maximum flow rate.
[0050] During a single breathing cycle, the intermediate phase occurs in time between the initial phase and the final phase.
[0051] This feature makes it possible to compensate for a possible restriction of the flow rate in one of the valves by introducing a missing amount of gas during an intermediate phase. It is thus possible to smooth the transition between the initial phase and the final phase.
[0052] The control system may be configured to control the gas mixture inlet valve and / or the dilution gas inlet valve to deliver a gas mixture including both breathable gas and dilution gas during a transition phase of a breathing cycle, with the flow rate of breathable gas decreasing as the flow rate of dilution gas increases.
[0053] The control system may be configured to perform a calculation to correct the proportion of breathable gas in the delivered gas mixture based on a ratio or a proportional-integral calculation of the proportion of breathable gas delivered and the proportion of desired breathable gas.
[0054] This feature makes it possible to correct constant offset errors which a simple ratio corrector cannot correct in a simple manner.
[0055] The invention also relates to a method for controlling the proportion of breathable gas in a gas mixture delivered by a breathing system as defined above, the method comprising at least:
[0056] - a dispensing step during which a gas mixture comprising a certain proportion of breathable gas and a certain proportion of diluent gas is dispensed;
[0057] - a measuring step, during which at least one sensor measures information representative of the proportion of breathable gas in the delivered gas mixture,
[0058] - a calculation step, during which the control system calculates the proportion of breathable gas delivered,
[0059] a deviation calculation step, during which the control system calculates the deviation between the proportion of breathable gas delivered and the proportion of breathable gas desired, and
[0060] - a control step during which the control system (40) controls the gas mixture inlet valve and / or the dilution gas inlet valve to adjust the flow rate through the gas mixture inlet valve and the flow rate through the dilution gas inlet valve at least according to the calculated deviation. BRIEF DESCRIPTION OF THE DRAWINGS
[0061] [ Figure 1 ] Figure 1 is a schematic diagram of a respiratory system according to the present invention;
[0062] [ Figure 2 ] Figure 2 Is Figure 1 Representation of the control loop implemented by the respiratory system;
[0063] [ Figure 3 ] Figure 3 is a graphical representation of the gases delivered during a breathing cycle;
[0064] [ Figure 4 ] Figure 4 is a graphical representation of the gas delivered during a breathing cycle when the maximum flow rate of one of the valves becomes limiting;
[0065] [ Figure 5a ][ Figure 5b ] Figure 5a and 5b is a graphical representation of gas delivered during a plurality of breathing cycles including alternating dispensing of a gas mixture and a diluent gas; and
[0066] [ Figure 6 ] Figure 6 is a graphical representation of the gas delivered during a breathing cycle including the transition phase. DETAILED DESCRIPTION
[0067] exist Figure 1 A breathing system 1, in particular for a spacecraft, is schematically represented in . This breathing system 1 is intended to deliver or distribute a gas mixture comprising a breathable gas to at least one of the occupants of the spacecraft.
[0068] The dispensing of the gas mixture may occur from a breathable gas source. This breathable gas source may be a gas mixture that may include oxygen or molecular oxygen (these terms are used interchangeably herein), or highly oxygen-enriched air, stored in one or more cylinders or in a pressurized oxygen reserve disposed on the spacecraft.
[0069] The oxygen supply may be replaced by an onboard oxygen generating system, such as one or more onboard oxygen generator systems (also referred to by the acronym OBOGS) supplied with air by the compressor of one or more engines.
[0070] The onboard oxygen generating system may also comprise a molecular sieve oxygen generating system (also referred to by the acronym MSOGS) arranged to provide oxygen enriched air at a desired oxygen concentration by adsorbing nitrogen from air supplied to the system.
[0071] The occupant may be, for example, a pilot of a spacecraft, whose alertness and performance are always critical. Therefore, he must receive oxygen in sufficient quantities and in proportions adapted to the critical situation he faces.
[0072] The breathing system 1 comprises a regulator 10 capable of delivering a flow of gas to a distribution member. The distribution member comprises at least one tube 20 suitable for allowing the circulation of a gas mixture comprising a breathable gas, and a mask 30 intended for distributing the gas mixture comprising a breathable gas to an occupant.
[0073] Breathing system 10 also includes a control system 40 .
[0074] The regulator 10 comprises a gas mixture inlet 11. The gas mixture inlet 11 may be connected to a source of breathable gas 12, in particular a first source of breathable gas, such as pure oxygen from a pressurized cylinder.
[0075] exist Figure 1 In the specific example of the present invention, the regulator 10 is a remote regulator. In particular, the regulator 10 can be fixed to the spacecraft. The regulator 10 can then be connected to the mask 30 by means of a tube 20 suitable for allowing the circulation of a gas mixture including a breathable gas.
[0076] Alternatively, the regulator 10 may be worn on a mask 30 and connected to a source of breathable gas 12 via a tube 20 adapted to allow circulation of a gas mixture comprising the breathable gas and / or via an auxiliary tube.
[0077] The gas mixture inlet 11 includes a gas mixture inlet valve 13 adapted to adjust the flow rate of the gas mixture flowing through the gas mixture inlet 11 .
[0078] The gas mixture inlet valve 13 is in particular an electronic valve comprising a control device 14 adapted to control the flow rate of the gas flowing through the gas mixture inlet valve 13. Furthermore, the gas mixture inlet valve 13 may have a direct or an amplified actuation.
[0079] The control device 14 is for example of piezoelectric, electromagnetic, electrostatic, pneumatic or some other type. It may be for example a linear or rotary actuator.
[0080] The regulator 10 may further include a first sensor 15. The first sensor 15 may be a flow sensor adapted to measure the flow rate of the gas mixture flowing through the gas mixture inlet valve 13.
[0081] The first sensor 15 is, for example, a thermal sensor (in particular of the hot wire probe type), an acoustic sensor (in particular of the Doppler effect type), a mechanical sensor (in particular of the cantilever or Coriolis effect type), an air sensor (in particular of the Venturi effect type) or a pressure loss sensor.
[0082] Additionally or alternatively, a pressure sensor positioned according to the geometry of the gas mixture inlet valve 13 and the dispensing components comprising at least the tube 20 and the mask 30 also makes it possible to obtain flow rate values according to Bernoulli's principle or Poiseuille's law.
[0083] The tube 20 is advantageously flexible or at least partially flexible, in particular in the portion connected to the mask 30. A first end 21 of the tube 20 is connected to the regulator 10. A second end 22 of the tube 20 is connected to the mask 30.
[0084] The tube 20 fluidly connects the gas mixture inlet valve 13 to the mask 30 so that the gas mixture or breathable gas flowing through the gas mixture inlet valve 13 is delivered to an occupant wearing the mask 30 via the inhalation valve 23 .
[0085] The mask 30 is an oronasal mask that can be placed on the face of an occupant or wearer to whom a gas mixture including breathable gas is to be delivered. The mask is preferably arranged on the face of the wearer of the mask 30 in a sealing manner.
[0086] To this end, the mask 30 may be provided with a retaining device for ensuring that the mask 30 remains on the face of the occupant. Such retaining device is, for example, an elastic harness, a bayonet fastening system or a mechanical harness.
[0087] The mask 30 is generally concave and defines an interior space 33. When the mask 30 is secured to the wearer's face, the wearer's skin closes off the interior space 33 in which the wearer can inhale and exhale.
[0088] In the configuration where the regulator 10 is a remote regulator, the mask 30 includes an inhalation valve 23 to which the tube 20 leads, which is capable of allowing the gas mixture or breathable gas to pass from the tube 20 into the interior space 33.
[0089] Alternatively, in a configuration where the regulator 10 is worn on a mask 30, there is no inhalation valve.
[0090] Furthermore, the mask 30 comprises a dilution gas inlet 31 comprising a dilution gas inlet valve 32 allowing dilution gas to enter the inner space 33, in particular from the external environment.
[0091] The mask 30 also advantageously includes an exhalation valve, not shown. The exhalation valve is adapted to allow the exhalation of the wearer's exhaled gases to escape.
[0092] The dilution gas inlet valve 32 may be an electronic valve comprising a control device 34 adapted to control the flow rate of the gas flowing through the dilution gas inlet valve 32 .
[0093] The dilution gas inlet valve 32 may further include a second sensor 35. The second sensor 35 may be a flow rate sensor adapted to measure the flow rate of the gas flowing through the second valve 32.
[0094] The second sensor 35 is, for example, a thermal sensor (in particular of the hot wire probe type), an acoustic sensor (in particular of the Doppler effect type), a mechanical sensor (in particular of the cantilever or Coriolis effect type), an air sensor (in particular of the Venturi effect type) or a pressure loss sensor.
[0095] Furthermore, the mask 30 further comprises a pressure sensor 36 adapted to measure the pressure in the inner space 33 .
[0096] The control system 40 is connected to the control device 14 of the gas mixture inlet valve 13, the control device 34 of the dilution gas inlet valve 32, the first sensor 15 of the regulator 10, and the second sensor 35 of the dilution gas inlet 31. In addition, the control system 40 can also be connected to the pressure sensor 36.
[0097] The control system 40 is, for example, a circuit board comprising at least one processor adapted to execute programs, and at least one memory storing instructions for executing these programs.
[0098] According to another embodiment, the control system 40 may also be fully analog. The control system 40 may also comprise a control logic or control electronics and power electronics for controlling the gas mixture inlet valve 13 .
[0099] The control system 40 is particularly configured to measure the flow rates in the gas mixture inlet valve 13 and the dilution gas inlet valve 32 by utilizing the first sensor 15 of the regulator 10 and / or the second sensor 35 of the dilution gas inlet 31. The control system 40 is capable of calculating the oxygen proportion in the gas mixture delivered to the wearer based on the flow rates in the gas mixture inlet valve 13 and the dilution gas inlet valve 32. In addition, the control system 40 is capable of adjusting the commands to the gas mixture inlet valve 13 and the dilution gas inlet valve 32 based on the measured oxygen proportion in the gas mixture and the desired oxygen proportion in the gas mixture.
[0100] The oxygen proportion in the desired gas mixture is stored, for example, in a memory. Alternatively, the oxygen proportion in the desired gas mixture can be calculated from information inherent to the breathing system 1 and data stored in the memory. If the breathing system 1 is suitable for installation in a spacecraft, the inherent information is specifically flight data.
[0101] A method for controlling the proportion of oxygen in a delivered gas mixture follows a control loop implemented by the breathing system 1. Figure 2 As shown, the method for controlling the proportion of oxygen in the delivered gas mixture follows a feedback loop.
[0102] The control method provides: a first actuation step 101, during which the control device 14 of the gas mixture inlet valve 13 is actuated by the control system 40; and a second actuation step 102, during which the control device 34 of the second valve 32 is actuated by the control system 40, for example based on the initial flow rate value D stored in the memory. 0 The first actuation step 101 of the control device 14 for the gas mixture inlet valve 13 and the second actuation step 102 of the control device 34 for the second valve 32 may be performed successively or simultaneously in time.
[0103] At the end of the first actuation step 101 and the second actuation step 102, the control method provides a dispensing step 103 during which the gas mixture is dispensed to the wearer. In the dispensing step 103, the gas mixture comprises an initial proportion of oxygen.
[0104] Subsequently, the control method provides a measuring step 104 during which the flow rates through the gas mixture inlet valve 13 and the dilution gas inlet valve 32 are measured by means of the first sensor 15 and the second sensor 35 controlled by the control system 40 , respectively.
[0105] The ratio of the flow rates through the gas mixture inlet valve 13 and the dilution gas inlet valve 32 constitutes information indicative of the proportion of oxygen in the delivered gas mixture.
[0106] For this purpose, the control method provides a calculation step 105 during which the oxygen proportion in the gas mixture is calculated in the control system 40 .
[0107] Finally, the control method provides a deviation calculation step 106, during which the oxygen proportion in the delivered gas mixture is calculated relative to the desired gas mixture F. O2 The deviation between the oxygen ratio in
[0108] The deviation calculation may include an integral component or a pseudo-integral component having a cutoff frequency suitable for providing similar results, between 0.1 Hz and 1 Hz, specifically between 0.1 Hz and 0.75 Hz, and more specifically between 0.16 Hz and 0.75 Hz, and more specifically around the respiratory frequency between 0.16 Hz and 0.5 Hz.
[0109] Finally, the control method provides a control step 107 during which new control values for the gas mixture inlet valve 13 and the dilution gas inlet valve 32 are then determined in order to adjust the oxygen proportion in the delivered gas mixture.
[0110] The control method is iterated to improve the accuracy of the oxygen fraction in the gas mixture delivered to the wearer relative to a set value.
[0111] According to a particular dilution method, the distribution of the gas mixture comprising a certain proportion of oxygen can be performed by serial dilution.
[0112] Advantageously, the dilution is carried out according to the dilution-on-demand method; the principle of this method is Figure 3 and 4 In the diagram, Figure 3 and 4A graphical representation of the gas delivered during a breathing cycle and during a breathing cycle where the maximum flow rate of the gas mixture inlet valve 13 and / or the dilution gas inlet valve 32 becomes limited, respectively.
[0113] therefore, Figure 3 is a graphical representation of the evolution of the dispensed flow rate D of the gas mixture over time t during inhalation by the wearer of the mask 30 .
[0114] The start of inhalation by the wearer of the mask 30 is detected by means of a pressure sensor 36 adapted to measure the pressure in the interior space 33 and controlled by a control system 40. The occurrence of a negative pressure in the interior space 33 corresponds to the start of inhalation and triggers the dispensing of the gas mixture.
[0115] In the initial stage P i During this time, the gas mixture inlet valve 13 is open and the dilution gas inlet valve 32 is closed, so that the gas mixture mainly comprises breathable gas, in particular more than 90% of the flow rate is breathable gas, and advantageously only breathable gas.
[0116] Initial stage i The duration of the gas mixture depends on the flow rate D of the gas mixture, the proportion of oxygen in the desired gas mixture and an estimate of the wearer's inspiratory volume, so that in the initial phase P i The total volume of oxygen in the gas mixture delivered during the period corresponds to the product of the desired fraction of oxygen in the gas mixture and the wearer's inhalation volume. The volume of oxygen in the gas mixture delivered corresponds to the initial stage P i The area under the curve of the flow rate D during the period.
[0117] In the initial stage P i At the end, in the final stage P f During this period, the gas mixture inlet valve 13 is then closed and the dilution gas inlet valve 32 is opened. f During this time, the gas mixture comprises mainly the diluent gas, in particular more than 90% of the flow rate, and advantageously only the diluent gas.
[0118] Final Stage f This lasts until the wearer's inhalation ends, which is associated with the disappearance of the negative pressure measured in the interior space 33 and, depending on the circumstances, with the emergence of an overpressure in the interior space 33. f The volume of dilution gas delivered during the period corresponds to the volume of dilution gas delivered during the final stage P f The area under the curve of the flow rate D during the period.
[0119] The sum of the volumes of oxygen and diluent gas is recorded as an updated value of inspiratory volume by the control system 40. The proportion of oxygen actually delivered during inspiration is calculated in order to implement the control loop described above.
[0120] This approach allows the feedback to be adapted to changes in breathing rate and inspiratory volume of the wearer of the mask 30, particularly when external conditions change, especially during stress phases.
[0121] In addition, in the initial stage P i The delivery of oxygen during this period makes it possible to compensate for the oxygen losses into the inspiratory dead volume comprising only diluent gas.
[0122] The limiting factor of the control method and therefore of the staged dilution is the presence of a respective maximum flow rate Dmax of the gas mixture inlet valve 13 and the dilution gas inlet valve 32. This maximum flow rate Dmax prevents the delivery of sufficient oxygen or dilution gas to satisfy the inspiratory flow rate during a portion of inspiration.
[0123] This occurs especially when inspiration is short and has high peaks in flow rate, such as during stress phases. This also occurs when breathing is fast and causes discomfort during inspiration.
[0124] To overcome this problem, Figure 4 As shown ( Figure 4 is a graphical representation of the gas delivered during a breathing cycle when the maximum flow rate of one of the valves becomes limited), the control system 40 triggers the intermediate stage P r , during which the valve that is limiting the flow rate delivers its maximum flow rate. In this configuration, the other valve delivers additional flow rate to meet the inspiratory flow rate.
[0125] exist Figure 4 In the example shown, the gas mixture inlet valve 13 is a flow restricting valve and is delivering its maximum flow rate Dmax. Therefore, the dilution gas inlet valve 32 is opened to deliver an additional flow rate, which is represented by the area above the dashed line corresponding to the value Dmax of the maximum flow rate of the limited gas mixture inlet valve 13, and the continuous curve represents the flow rate D as a function of time t.
[0126] By in the initial stage P i and intermediate stage P r The proportion of oxygen delivered is calculated geometrically by summing the areas of oxygen under the curve corresponding to flow rate D in order to implement feedback as described above.
[0127] In the example described, the information relating to the proportion of breathable gas is the ratio of the volumes passing through the gas mixture inlet valve 13 and the dilution gas inlet valve 32 .
[0128] Other types of information may be obtained by utilizing different sensors. For example, it may be possible to use an oxygen sensor mounted on the mask 30 to directly measure the oxygen fraction in the delivered gas mixture. Alternatively, the oxygen sensor may be positioned to measure the proportion of oxygen in the wearer's exhaled gas. This may then be advantageously measured by using CO 2 The sensor obtains CO in the exhaled breath 2 The information is supplemented by measurements of ratios.
[0129] Furthermore, multiple initial phases P can be envisioned to occur during the same respiratory cycle. i and multiple final stages P f , specifically, they occur alternately with each other. Figure 5a and 5b Two graphical representations of gas delivered during a breathing cycle are shown, the breathing cycle including multiple alternations between dispensing of a gas mixture and a diluent gas.
[0130] Thus, depending on the number of alternations and / or depending on the duration of the breathing cycle, in particular the duration of the inhalation of the occupant wearing the mask 30, the breathing cycle may end in the following phases:
[0131] ● Final stage of distribution of dilution gas P fm ,like Figure 5a As shown;
[0132] or
[0133] ● Initial phase P of dispensing a gas mixture consisting mainly of breathable gases im+1 ,like Figure 5b shown.
[0134] Alternating in this way makes it possible to supply pure oxygen at the start of breathing while cycling several times per inhalation cycle on the mass of the air / oxygen mixture supplied. Thus, a quicker reaction is possible in situations where the inhalation pattern changes rapidly in frequency and amplitude.
[0135] Similarly, the volume of oxygen in the gas mixture delivered during the breathing cycle corresponds to the volume of oxygen in each initial phase P i1 , P i2 ,...P im , P im+1 Similarly, the volume of dilution gas delivered during the breathing cycle corresponds to the volume of gas delivered during each final phase P f1 , P f2 ,...P fm The sum of the areas under the curves for the flow rates D during the period. The sum of the volumes of oxygen and diluent gas is recorded by the control system 40 .
[0136] In addition, in order to keep the occupant wearing the mask 30 comfortable, it is conceivable that in the initial stage P i With the final stage P f Provide a transition phase between t .
[0137] In the transition phase t During this period, the distribution of the gas mixture gradually decreases, while the distribution of the diluent gas gradually increases, thereby generating a distribution transition.
[0138] Assign transition by Figure 6 The dashed curve in represents that Figure 6 In this transition phase P t A graphical representation of the gases delivered during a breathing cycle.
[0139] Transition phase t The duration of the transition phase P is adjustable. t This can be extended until the breathing cycle is complete.
[0140] Transition phase t It makes it possible to avoid any risk associated with a potential absence of distribution of the gas mixture and / or of the dilution gas during the switch from the initial phase to the final phase.
[0141] In practice, the switch from the initial phase to the final phase results in a momentary closing of the gas mixture inlet valve 13 , accompanied by a momentary opening of the dilution gas inlet valve 32 .
[0142] Thus, due to possible delays or mechanical lags, even the smallest time periods during which there is no dispensing of the gas mixture and / or dilution gas may be perceptible. This may be felt by the occupant wearing the mask 30 and lead to a distraction or even a hindrance to him. This is even more harmful if the occupant wearing the mask 30 is the pilot of the spacecraft.
[0143] It is conceivable that all types of physiological sensors are used to discover the physiological state of the occupant wearing the mask 30, in particular the blood oxygen level of the occupant wearing the mask. It is also possible to measure the blood composition of the occupant wearing the mask via measuring the arterial blood oxygen saturation SaO2 or measuring the pulse blood oxygen saturation SpO2. These data will be measured by an ABG analyzer (SaO2) or a pulse oximeter (SpO2) and used to implement a feedback loop.
[0144] Furthermore, it is also possible to discover the physiological state of the occupant wearing the mask, in particular by analyzing the exhaled breath, measuring brain activity and / or measuring the blood flow of the occupant wearing the mask.
[0145] Obviously, the present invention is not limited to the above-mentioned embodiments and is provided only as examples. It covers various modifications, alternative forms and other variations that can be conceived by technicians in the field within the framework of the present invention, and in particular, all combinations of the above-mentioned various operating modes that can be viewed individually or in association.
Claims
1. A breathing system (1), in particular for a spacecraft, comprising: - a distribution member (20, 30) suitable for delivering the gas mixture to at least one occupant, a gas mixture inlet (11) connectable to a source of breathable gas (12), said gas mixture inlet comprising a gas mixture inlet valve (13) intended to adjust the proportion of breathable gas in said gas mixture, a dilution gas inlet (31) connectable to a dilution gas source, said dilution gas inlet comprising a dilution gas inlet valve (32) intended to adjust the proportion of dilution gas in said gas mixture, - at least one sensor (15, 35) adapted to measure information representative of the proportion of breathable gas in the gas mixture delivered by the dispensing member (20, 30), and - A control system (40) configured to adjust the ratio of breathable gas delivered according to the measured information, and to control the gas mixture inlet valve (13) and the dilution gas inlet valve (32) according to the ratio of breathable gas delivered and the ratio of breathable gas required.
2. Breathing system (1) according to the preceding claim, characterized in that The sensor (15, 35) may include a first flow meter (15) adapted to measure the flow rate of the breathable gas through the gas mixture inlet valve (13), and / or a second flow meter (35) adapted to measure the flow rate of the dilution gas through the dilution gas inlet valve (32), and / or an oxygen sensor, and / or a physiological sensor.
3. A breathing system (1) according to any one of the preceding claims, characterized in that The dispenser part (30) comprises a mask (30) and means (36) for detecting an inhalation phase, in particular a pressure sensor (36) which is particularly suitable for measuring the pressure in an interior space (33) of the mask (30).
4. A breathing system (1) according to any one of the preceding claims, characterized in that The control system (40) is configured to detect inhalation of the occupant and to vary the flow rate and / or volume through the gas mixture inlet valve (13) and / or through the dilution gas inlet valve (32) during a breathing cycle.
5. Breathing system (1) according to the preceding claim, characterized in that The control system (40) is configured to control the gas mixture inlet valve (13) and the dilution gas inlet valve (32) to deliver: a gas mixture during at least one initial phase (Pi) of a breathing cycle, the gas mixture comprising, for example, at least 60% of breathable gas, in particular at least 75% of breathable gas, and more particularly at least 90% of breathable gas, and - at least one final phase (P f ) during the step of: the gas mixture comprising, for example, at least 60% of the dilution gas, specifically at least 75% of the dilution gas, and more specifically at least 90% of the dilution gas.
6. The breathing system (1) according to claim 4 or 5, characterized in that The control system (40) is configured to calculate an average delivered ratio of breathable gas during the breathing cycle and to adjust the flow rates through the gas mixture inlet valve (13) and the dilution gas inlet valve (32) during a subsequent inhalation based on the average ratio of breathable gas.
7. The breathing system (1) according to any one of claims 4 to 6, characterized in that The control system (40) is configured to repeatedly measure the flow rate through the gas mixture inlet valve (13) and / or through the dilution gas inlet valve (32) during the breathing cycle, and to control the gas mixture inlet valve (13) and the dilution gas inlet valve (32) based on the ratio of the delivered breathable gas and the ratio of the desired breathable gas.
8. Breathing system (1) according to the preceding claim, characterized in that The control system (40) is configured to control the gas mixture inlet valve (13) and / or the dilution gas inlet valve (32) to adjust the gas mixture inlet valve (13) and / or the dilution gas inlet valve (32) in the middle phase (P r ) during which the gas mixture comprising both breathable gas and dilution gas is delivered, the gas mixture inlet valve (13) and / or the dilution gas inlet valve (32) being operated at a maximum flow rate (Dmax).
9. Breathing system (1) according to the preceding claim, characterized in that The control system (40) is configured to control the gas mixture inlet valve (13) and / or the dilution gas inlet valve (32) to adjust the gas mixture inlet valve (13) and / or the dilution gas inlet valve (32) during the transition phase (P t ) during which the gas mixture comprising both breathable gas and dilution gas is delivered, and when the flow rate of the dilution gas increases, the flow rate of the breathable gas decreases.
10. The breathing system (1) according to any one of the preceding claims, characterized in that The control system (40) is configured to perform a calculation to correct the proportion of breathable gas in the delivered gas mixture based on a ratio or a proportional-integral calculation of the proportion of the delivered breathable gas and the proportion of the desired breathable gas.
11. A method for controlling the proportion of a breathable gas in a gas mixture delivered by a breathing system (1) according to any one of the preceding claims, the method comprising at least: - a dispensing step (103), during which a gas mixture comprising a proportion of breathable gas and a proportion of diluent gas is dispensed; - a measuring step (104), during which at least one sensor (15, 35) measures information representative of the proportion of breathable gas in the delivered gas mixture, - a calculation step (105), during which the control system (40) calculates the proportion of breathable gas delivered, - a deviation calculation step (106), during which the control system (40) calculates the deviation between the delivered proportion of breathable gas and the desired proportion of breathable gas, and - a control step (107), during which the control system (40) controls the gas mixture inlet valve (13) and / or the dilution gas inlet valve (32) to adjust the flow rate through the gas mixture inlet valve (13) and / or the flow rate through the dilution gas inlet valve (32) at least according to the calculated deviation.