EP0483020B1 - Aircrew breathing protection gear - Google Patents

Description

The invention relates to respiratory equipment intended to protect aircraft crew members during flights at high altitude and / or under high load factor, requiring to supply a respiratory mask with gas under a pressure higher than that of the 'ambiance.

To protect the crew members against the risks of anoxia and aeroembolism, an overpressure is generally established in the cockpit of an aircraft, from 1500 m onwards, which is increased with altitude. The respiratory equipment includes a mask which a demand regulator supplies first with dilute oxygen, then with pure oxygen under a pressure such that the partial pressure of oxygen in the lungs remains sufficient. The equipment is also provided to supply the mask, in the event of ejection or loss of pressure in the passenger compartment at high altitude, with oxygen under sufficient pressure to avoid loss of consciousness.

The member or each member of the crew of a combat aircraft, the evolutions of which cause high accelerations along the vertical plane, is furthermore provided with a device for protection against acceleration, comprising pants provided with connected inflatable pockets. to a control valve, called an anti-g valve, which supplies a pressure which is a function of acceleration.

It has already been proposed (US-A-4,230,097) on the one hand to increase the overpressure of the respiratory supply gas supplied to the mask in the event of acceleration to increase resistance to it, on the other hand - if breathing gas is supplied under high pressure to the mask - pressurize the pants pockets to create compensation.

When the mask is supplied with pressurized respiratory gas, it tends to peel off the face which makes leaks reduce respiratory overpressure. To solve this problem, known protective equipment (US-A-4,172,455) comprises a mask mechanically connected to a helmet provided with an inflatable neck pocket and regulating means for supplying the mask and the neck pocket. under the same pressure, which is a function of the ambient pressure and / or the load factor. The output of the respiratory regulator at the request of this equipment is connected by a first conduit, called "caterpillar" or "elephant's trunk", to the mask and by another conduit to the neck pocket.

This provision has not been found to be completely satisfactory. Because the padding of the helmet is deformable, the force of application of the mask on the face is insufficient and contact with the skin is not effectively ensured. In addition, the force of application of the mask against the face due to the pressure of the pocket increases more slowly than the pressure in the mask, resulting in particularly large leaks during an initial feeding phase.

The invention aims in particular to provide equipment improving the protection of the crew when the flight conditions make it necessary to supply the breathing gas under a pressure significantly higher than that of the atmosphere.

For this purpose, the invention provides in particular protective equipment according to claim 1.

The invention also aims, in the case of protective equipment intended for an aircraft capable of reaching very high altitudes, to improve the protection of the crew in the event of the appearance of conditions requiring a sudden and significant increase in the breathing gas supply pressure. In conventional equipment, the delay in swelling of the bag results in significant initial leaks slowing the rise in pressure of the respiratory gas inhaled by the wearer of the bag. mask. To solve this problem, the regulating means are advantageously provided to supply the pneumatic means with a gas flow rate sufficient to cause a pressure build-up speed greater than that of the pressure build-up in the mask.

According to yet another aspect of the invention, usable in protective equipment comprising an anti-g valve provided for establishing, in the absence of acceleration, in the pants pockets, a pressure greater than the pressure prevailing in the mask and function of the latter, the regulating means advantageously comprise a circuit making it possible to supply the pneumatic means from the anti-g valve, under a pressure reduced compared to that supplied to the pants pockets, but greater than that of the respiratory gas supplied to the mask.

When, moreover, the regulating means are provided to supply the mask with gas under a pressure which increases as a function of the acceleration along the vertical plane, detected by an anti-g valve, it is advantageous to supply the pneumatic means from the anti-g valve with a time advance relative to the increase in the pressure of the respiratory gas sent to the mask.

The pneumatic means can be constituted by a neck pocket of known constitution. The action of this pocket can be supplemented or replaced by that of other means fulfilling the same function, namely exerting - directly or indirectly - a pressure force which keeps the edge of the mask applied against the face.

In particular, the pneumatic means may comprise an inflatable sealing rod, placed between the internal sealing lip of the mask face cover and the covering part, supplied by a circuit. This solution makes it possible to complete the action of the neck pocket or to replace it, although this substitution gives less favorable results.

We also know that the current trend is to equip the helmet with a viewfinder, which implies that the position of the helmet relative to the head is maintained with precision. In practice, this generally implies that the helmet is personalized and that the use of an inflatable neck pocket is avoided, the action of which tends to move the helmet relative to the head. The pneumatic means can then be incorporated into a strap connecting the mask to the helmet, the term "strap" being taken in a broad sense and as indicating any organ connecting the helmet to the mask and making it possible to press the mask against the face by resting on helmet.

• la figure 1 est un schéma de principe montrant un équipement de protection pour pilote d'aéronef, de constitution générale connue ;
• la figure 2 montre les courbes de variation de la pression dans le masque et dans la poche de nuque d'un casque dans le cas d'un équipement classique de protection et dans le cas d'un mode de réalisation de l'invention ;
• la figure 3 est un schéma de principe montrant des moyens d'alimentation de la poche de nuque conforme à un mode particulier de réalisation de l'invention, utilisable dans le cas d'un équipement de protection comportant une valve anti-g prévue pour gonfler les poches de pantalon sous une pression supérieure à celle du gaz respiratoire, au moins lorsque la pression respiratoire dépasse une valeur déterminée ;
• la figure 4, similaire à une fraction de la figure 3, montre une variante de réalisation ;
• la figure 5 montre la façon dont les moyens régulateurs d'un équipement selon l'invention peuvent être associés à un ensemble régulateur respiratoire-valve anti-g de constitution générale connue ;
• la figure 6, similaire à la figure 3, montre un mode de réalisation de l'invention applicable à un équipement de protection dont la valve anti-g n'est pas prévue pour mettre en pression les poches de pantalon en cas de surpression respiratoire.
• la figure 7 montre un exemple représentatif de courbes de la pression de sortie du régulateur respiratoire et la valve anti-g dans un équipement de protection ;
• les figures 8 et 81 montrent, respectivement en élévation et en coupe suivant la ligne A-A, une constitution possible de masque complétant l'action de la poche ou la remplaçant ;
• la figure 9 montre des courbes de variation de la pression dans le masque et dans la poche de nuque (et/ou le vérin pneumatique et/ou le boudin de masque) en fonction du temps, dans le cas d'un équipement dont le régulateur respiratoire fournit au masque une pression croissante avec l'accélération ;
• la figure 10 est un schéma montrant une constitution possible de moyens pneumatiques d'application de masque, complétant ou se substituant à la poche de nuque de la figure 1.

The invention will be better understood on reading the following description of particular embodiments of the invention, given by way of non-limiting examples. The description refers to the accompanying drawings, in which:

• FIG. 1 is a block diagram showing protective equipment for an aircraft pilot, of known general constitution;
• FIG. 2 shows the curves of variation of the pressure in the mask and in the nape pocket of a helmet in the case of conventional protective equipment and in the case of an embodiment of the invention;
• Figure 3 is a block diagram showing means for supplying the neck pocket according to a particular embodiment of the invention, usable in the case of protective equipment comprising an anti-g valve provided for inflating pants pockets under a pressure higher than that of the respiratory gas, at least when the respiratory pressure exceeds a determined value;
• Figure 4, similar to a fraction of Figure 3, shows an alternative embodiment;
• FIG. 5 shows how the regulating means of equipment according to the invention can be associated with a respiratory regulator-anti-g valve assembly of known general constitution;
• FIG. 6, similar to FIG. 3, shows an embodiment of the invention applicable to protective equipment, the anti-g valve of which is not intended to press the pants pockets in the event of respiratory overpressure.
• FIG. 7 shows a representative example of curves of the outlet pressure of the respiratory regulator and the anti-g valve in protective equipment;
• Figures 8 and 81 show, respectively in elevation and in section along the line AA, a possible constitution of mask completing the action of the pocket or replacing it;
• FIG. 9 shows curves of variation of the pressure in the mask and in the neck pocket (and / or the pneumatic cylinder and / or the mask flange) as a function of time, in the case of an equipment whose regulator breathing provides the mask with increasing pressure with acceleration;
• FIG. 10 is a diagram showing a possible constitution of pneumatic mask application means, supplementing or replacing the neck pocket of FIG. 1.

The protective equipment shown schematically in Figure 1 has a general constitution widely used at present on combat aircraft. It comprises a rigid helmet 10 and a respiratory mask 12 covering the nose and the mouth, connected to the mask by straps of adjustable length. An inflatable pocket 14 is placed inside the rigid shell of the helmet, against the occipital part of the head. This neck pocket is intended to press the mask against the face when the respiratory gas supplied to the mask 12 has an overpressure with respect to the atmosphere.

The equipment worn by the pilot also comprises a waistcoat or plastron 16 provided with chest pockets and pants 18 provided with pockets intended to clamp the soft parts of the legs, both inflatable.

The seat 20 carries means for supplying the mask and pockets which can be viewed as having a respiratory regulator 22 supplied with oxygen under pressure by an on-board source (converter of liquid oxygen or generator of oxygen-enriched air in general) and an anti-g 24 valve, generally supplied with air taken from a stage of the compressor of an engine although it can also be supplied by an on-board gas reserve. The outlet of the respiratory regulator 22 is connected to a caterpillar 26 for supplying the mask 12 and, via a connection 28, to the pockets of the vest. The anti-g valve 24 is connected to a connector 30 supplying the pockets of the pants 18.

The arrangement described so far being conventional there is no need to describe it further. As will be seen below, the invention is not applicable only to such equipment.

The regulating means of an equipment according to the invention comprise, in addition to the respiratory regulator 22, a circuit 32 whose output is, in the case of FIG. 1, connected by a pipe 34 to the neck pocket 14.

In equipment of the type which has just been described, the pressure variation as a function of time in the mask 12 and the chest pockets 16, in the event of sudden appearance of conditions making it necessary to create a pressure P₀ there, is of the kind shown by curve 36 in FIG. 2 if the neck pocket is supplied by a bypass taken from the track 26. The pressure in the neck pocket 14 increases more slowly, as indicated by curve 38; this pressure is not fully usable to apply the mask against the face due to the imperfect performance of the pocket, hence leaks. In addition, the pressure in the pocket, due to the volume of the latter and the compressibility of the helmet padding, increases much less quickly than in the mask.

The harmful consequences of these two phenomena are reduced by feeding the bag under a pressure P₀ + ΔP₀ greater than the respiratory overpressure sought in the mask 12
in case of altimetric compensation of the pants pockets
and / or if the pants pockets are inflated by the anti-g valve,
so as to have a growth curve of the kind shown at 40, placing itself above curve 36 as soon as possible.

The pressure difference ΔP₀ is chosen according to the efficiency of the neck pocket 14. In practice, it will generally be of the order of 30 hPa.

On the one hand, the overpressure ΔP₀ makes it possible to press the mask tightly against the face once the set pressure P₀ + ΔP₀ is reached, on the other hand it causes a more rapid increase in the pressure in the neck pocket 14, as indicated by curve 40 in phantom.

In the case where the anti-g valve 24 is coupled to the respiratory regulator 22 so as to supply the pockets of the pants 18 with gas under a pressure higher than the pressure of the respiratory gas, in the event of supply of the mask 12 under overpressure, the circuit 32 to add to a known type of equipment can be very simple.

In the case illustrated in FIG. 3, the circuit 32 includes an intake valve 42 and a deflation valve 44, each connecting the bag 14 to the outlet of the anti-g valve 24. The valve d admission 42 includes a valve 46 resting on a seat for communicating the inlet and outlet of the valve, carried by a membrane one side of which is subjected to outlet pressure and the other side of which is subjected at the pressure prevailing in a piloting chamber 48. The pilot pressure can be adjustable for example by a solenoid valve, as a function of parameters such as acceleration, external pressure, etc. The inlet valve 42 is connected to the pocket by means of a non-return valve 50 and a throttling valve 52 for limiting the flow. A calibrated valve 54 makes it possible to limit the overpressure in the pocket for example to a value of 120 hPa. In a circuit of the kind shown in FIG. 3, the overpressure created in the pocket 14 depends on the outlet pressure of the anti-g valve, itself a function of the respiratory overpressure and greater than the latter thanks to the pressure multiplier 61.

The exhaust valve 44 allows the bag 14 to empty into the atmosphere through a vent 56 when the outlet pressure of the anti-g valve, which prevails in a chamber 58, decreases.

The simplified alternative embodiment shown in FIG. 4 comprises an inlet valve 42a constituted by a simple valve calibrated by a spring 54 whose compression force fixes the difference between the outlet pressure of the anti-g valve and the pressure which s 'established in the back pocket 14.

• la valve anti-g 24 établisse, dans les poches du pantalon 18, une pression fonction de la surpression respiratoire et supérieure à elle,
• le régulateur respiratoire 22 établisse, dans le masque 12, une surpression fonction de la pression établie dans les poches du pantalon 18 par la valve anti-g 24 en cas d'apparition d'une accélération dirigée suivant la verticale avion.

The circuit 32 shown in FIG. 3 can in particular be used in respiratory equipment, the respiratory regulator 22 and the anti-g valve 24 have the constitution shown in FIG. 5 and are coupled to each other so that:

• the anti-g valve 24 establishes, in the pockets of the pants 18, a pressure which is a function of the respiratory overpressure and greater than it,
• the respiratory regulator 22 establishes, in the mask 12, an overpressure as a function of the pressure established in the pockets of the pants 18 by the anti-g valve 24 in the event of the appearance of an acceleration directed along the vertical plane.

It is not necessary to describe here the regulator 22 and the valve 24, the constitution of which can be very similar to that described in document US-A-4 230 097.

The outlet of the anti-g valve 24, the inlet 60 of which is connected for example to a stage of the engine compressor, controls the respiratory overpressure by means of a pressure reducing valve 62, for example in a ratio 1 / 10 (this value is not limiting). Conversely, the respiratory regulator 22 controls the overpressure in the pockets of the pants 18, in the absence of acceleration, by means of a pressure multiplication valve 64, of ratio 4/1 for example (this value does not again being given only as an example). A supply of oxygen under pressure to the anti-g valve 24 is then necessary: in FIG. 5, it is carried out by a nozzle 68 on the inlet 66 of the respiratory regulator 22.

FIG. 7 shows, by way of example, curves 70 and 72 representative of the outlet pressure of the anti-g valve 24 and of the regulator 22 as a function of the acceleration directed along the vertical plane G _z ; the anti-g valve feeds the pants pockets only after an acceleration of 2 g. In a variant, the feeding of the pockets is delayed up to 4 g, as shown by the dashed curve, which facilitates the feeding of the neck pocket in advance relative to the mask.

Protective equipment intended for aircraft not exceeding an altitude of about 15,000 m is often devoid of means making it possible to create pressure in the pockets of the pants in the event of respiratory overpressure.

In this case the circuit 32 may have the constitution shown in FIG. 6, where the members corresponding to those of FIGS. 3 and 4 bear the same reference number, assigned the index a.

The circuit of FIG. 6 essentially differs from that of FIG. 4 by the constitution of the evacuation or deflation valve 44a, which also constitutes a compensation valve, and which is supplied by the source anti-g valve 24. There is, in valve 44a, a membrane on which the outlet pressure of the anti-g valve 24 is exerted. This membrane is not directly linked to a communication communication valve. pocket 14 with a vent 56a. It is provided with a pusher 70 intended to exert a bearing force of the valve 72 for communicating with the vent when an overpressure prevails in the chamber 58a. The valve 72 is carried by an additional membrane 74 which defines, with the first membrane, a chamber 76 supplied by the respiratory regulator 22. This regulator supplies the neck pocket 14 by means of a throttle and an anti-valve -back 78.

This arrangement allows the discharge valve 44a to operate according to two compensation laws, one as a function of the respiratory overpressure, due to the presence of the membrane 74, the other as a function of the acceleration detected by the anti-g valve 24.

The invention is susceptible of numerous variant embodiments.

In particular, the pressure intended to ensure the seal can be established in a strap for pulling the mask towards the helmet, to press the mask against the face, and / or in an inflatable sealing rod, for example in the form of an iron horse opening upwards, bordering the face cover of the mask in addition to the pocket 14, or in its place. A connection 80 (Figure 3) is sufficient to supply the sealing rod.

FIGS. 8 and 8A show a possible constitution of a mask provided with such a tube. The elastomeric face cover 82 has a thick central part and / or reinforced by a shell 84. On the internal face of the peripheral part of the face cover can be stuck a rigid gutter, for example in the shape of a horseshoe releasing the bridge of the nose. An inflatable tube 86, connected to connection 80, is fixed, for example by gluing, on the gutter or in a fold of the thin part of the face cover. A stop 88 can be provided to limit its swelling and / or hold it in place.

When the circuit 32 does not provide pressure, the flange 86 has a minimum cross section. When the circuit 32, on the other hand, provides pressure, the tube inflates, tightens the straps and increases the seal.

FIG. 9 shows the curves of variation of the pressure, as a function of time t , in a device according to yet another alternative embodiment. Curve 90 shows the variation of the pressure in the mask 12 and the vest pockets. Curve 94 shows the pressure variation in the neck pocket and / or the inflatable strap and / or the sealing flange 88. In the illustrated case, the circuit 32 is designed to anticipate, for a time Δt, the rise in pressure in the mask. The final pressure reached in the neck pocket, the sausage or the strap is ΔP₁ higher than the final pressure in the mask. In practice, the value of ΔP₁ may vary depending on the efficiency of the pneumatic sealing means; in the case of a helmet pocket, it will often, in practice, be of the order of 30 hPa.

The curves in FIG. 9 can be obtained even if the final pressure in the acceleration protective clothing is equal to the pressure in the mask, insofar as the pressure necessary to supply the pocket, the flange and / or the strap is obtained from a valve providing overpressure as a function of acceleration.

FIG. 10 (where the components corresponding to those of FIG. 1 have the same reference number) shows an embodiment of the invention which is particularly advantageous when the helmet 10 is intended to receive a helmet viewfinder and is devoid of neck pocket. Such a helmet is generally personalized to the measurements of the pilot for whom it is intended and must remain within an immutable position in relation to the head. In this case it is preferable to incorporate the pneumatic means in a strap for connecting the mask to the helmet. In the case shown in Figure 10, the helmet can be considered integral, in the sense that it includes a front fairing 96, placed in front of the chin. To facilitate removal of the helmet, the fairing 96 can be fixed in a removable manner, for example by engagement and locking of two side blades 98 in housings 100 of the helmet. The mask 12 is then fitted into the fairing 96 and the pneumatic means can be constituted by at least one actuator or a pneumatic bellows interposed between the fairing and the rigid shell of the mask. In the case illustrated in FIG. 10, the body of a jack 102 is fixed to the fairing and the piston is connected to the shell of the face cover by ball joints 104. A spring 106 ensures permanent contact of the mask with the face.

The invention is susceptible of numerous variants of material still further, in particular as regards the pressure control. In particular, the pockets can be supplied by valves, piloted or not, electronically controlled, which in particular makes it possible to carry out any desired law and relationship between the mask pressures, pants pockets, chest pocket and helmet pocket (and / or possibly flange or pneumatic strap), in particular a linear relationship. Adaptable electronic control devices are already known, such as those described in patent US-A-4 336 590, with pilot valve, and those with progressive solenoid valve.

Claims (10)

1. Respiratory equipment for protecting the members of an aircraft crew when flying at high altitude and/or under a high load factor requiring a respiratory mask (12) for breathing gas at a higher than ambient pressure, the equipment comprising a mask (12) mechanically connected to a helmet (10) and means for adjusting the supply of respiratory gas to the mask at a pressure which depends on the altitude and/or the acceleration,
   characterised in that the adjusting means are designed to produce, in pneumatic means exerting a force pressing the edge of the mask against the face, a pressure greater than the pressure of the respiratory gas supplied to the mask (12), at least when the mask supply pressure exceeds a predetermined threshold value.
2. Protective equipment according to claim 1 for an aircraft for flying at high altitudes,
   characterised in that the adjusting means are adapted to supply the pneumatic means with gas at a flow rate sufficient to produce a pressure rise at a speed greater than the pressure rise in the mask.
3. Equipment according to claim 1 or 2 comprising at least one anti-g valve (24) adapted to produce a pressure in the trouser pockets greater than the pressure in the mask and dependent thereon, even in the absence of acceleration, when the mask is supplied with gas under pressure,
   characterised in that the adjusting means comprise a circuit (42, 44) for supplying the pneumatic means from the anti-g valve at a pressure below the pressure supplied to the trouser pockets but above the pressure of the respiratory gas supplied to the mask.
4. Equipment according to claim 1, 2 or 3, comprising coupling means (62) causing the mask-adjustment means to supply gas at a pressure which increases with the vertical acceleration of the aircraft detected by an anti-g valve (24),
   characterised in that the adjusting means are adapted to supply the pneumatic means from the anti-g valve at a pressure above the pressure in the mask and/or in advance of the increase in pressure of the respiratory gas supplied to the mask.
5. Equipment according to claim 4, characterised in that the coupling means comprise an inlet valve (42) and a deflating valve (44), both connecting the pneumatic means to the outlet of the anti-g valve (24), the escape valve (44) enabling the pneumatic means to empty to atmosphere via a vent (56) when the outlet pressure of the anti-g valve decreases.
6. Equipment according to claim 5,
   characterised in that the inlet valve (42) comprises a flap (46) which rests on a seat for connecting the inlet to the outlet of the valve and is borne by a diaphragm, one surface of which is subjected to the outlet pressure and the other surface to the pressure in a control chamber (48) at a pressure which is adjustable in dependence on the acceleration or the external pressure.
7. Equipment according to claim 4,
   characterised in that the deflating valve (44a) comprises a diaphragm subjected to the outlet pressure of the anti-g valve (24) and comprising a push rod (70) adapted to exert a bearing force on a flap (72) for connecting the pneumatic means to a vent, the flap (72) being borne by an additional diaphragm (74) which, in co-operation with the first diaphragm, bounds a chamber (76) supplied by the respiratory adjustment means (22), which also supplies the resilient means via a constriction and a non-return valve (78).
8. Equipment according to any of the preceding claims,
   characterised in that the pneumatic means comprise a nape-of-the-neck pocket (14) of the helmet or an inflatable seal tube (86) around the face of the mask.
9. Equipment according to any of the preceding claims,
   characterised in that the pneumatic means comprise a strap (98) connecting the mask to the helmet.
10. Equipment according to claim 9,
    characterised in that the helmet is of the integral kind and the belt has a jack (102) interposed between the face of the mask (12) and a front fairing (96) belonging to the strap.

Images