The present invention relates to a respiration air supply unit, intended for connection to a compressed air system, at least comprising: a housing, at least provided with an air inlet, which is provided with an inlet valve, a first air outlet, which is intended for supplying air coming from the air inlet to a user, and a pressure- sensitive membrane, the air inlet valve being operated as a result of the deflection of the pressure-sensitive membrane, and at least a second air outlet, which is intended for discharging the air exhaled by the user, and is provided with a first outlet valve, which allows air through when the pressure exceeds a first predetermined value.

Such a unit is known in practice, and is used in, for example, skin diving aε part of a two-stage respiration system.

Such a system usually comprises a compressed air cylinder containing compressed air at high pressure, for example at about 20 MPa, or another gas mixture which is suitable for breathing (simply described below as: air) . Connected to the outlet of such a compressed air cylinder is a first valve unit, which serves to reduce the pressure of the air from the compressed air cylinder to, for example, 1.3 MPa. By way of a supply hose the outlet of the first valve unit is connected to the diver's mouthpiece. However, in order to make the air coming from the first valve unit suitable for breathing, there is a second lowering of the pressure. The mouthpiece in this case is designed in such a way that the pressure of the air supplied through the mouthpiece to the diver depends on the diver's air requirements. For this purpose, the mouthpiece is provided with a flexible pressure-sensitive membrane which undergoes a certain deflection during inhaling and exhaling, and by means of which the diver's air requirements are established. This deflection causes an inlet valve in the mouthpiece to open, which inlet valve

allows air coming from the first valve unit to flow into the mouthpiece. During inhalation, depending on the extent of the inhalation, the inlet valve will be opened to a greater or lesser extent, and more or less air will thus be allowed through. When inhalation stops, the membrane will return to its neutral position in the housing, while when there is exhalation the membrane will undergo a deflection in the opposite direction. In both cases the inlet valve in the mouthpiece will be closed. During exhalation an outlet valve will also be opened, in order to allow the exhaled air to escape.

Should a diver have an accident under water, or should the diver's partner observe that breathing has stopped, through the fact that he no longer sees air bubbles coming out of the mouthpiece or that the mouthpiece is no longer in the diver's mouth, the current procedure is that the victim first has to be brought to the surface and is then resuscitated at the surface, on board a boat or on land. This is because the present respiration air supply units are not designed for performing artificial respiration on users.

The object of the present invention is therefore to provide a respiration air supply unit by means of which a victim can also be given artificial respiration. For this purpose, the unit according to the invention is characterized by control means for loading the first outlet valve in the opening direction and for opening the inlet valve, and by pressure-regulating means which prevent the outflow of air through at least the second air outlet until a second predetermined air pressure is reached, which second predetermined air pressure is greater than the first predetermined air pressure.

This makes it possible to administer air to a victim using a respiration air supply system according to the invention, in the course of which air pressure which will be maximum the value of the second predetermined air pressure is built up. When this pressure is reached the second air outlet will be opened and the excess air supplied can be discharged through said second outlet. This

second predetermined air pressure will have to have such a value that a victim who has air administered to him with a respiration air supply system according to the invention does not suffer any harmful consequences through the fact that too great a pressure has been able to build up in his lungs.

According to an advantageous embodiment of a respiration air supply system according to the invention, when the control means are operated the inlet valve shuts under the influence of the deflection of the pressure- sensitive membrane occurring at a third predetermined air pressure, which air pressure lies between the first predetermined air pressure and the second predetermined air pressure. When air is being administered to a victim with such a respiration air supply system, pressure is also built up, until a pressure corresponding to the value of a third predetermined air pressure is reached, in which case the inlet valve shuts off the inlet opening. This pressure is also selected in such a way that the victim does not suffer any harm through excessive pressure being placed on his lungs. If it is found that the inlet opening is still allowing air through, for example through the inlet valve having a defect, then the second outlet will be opened at any rate when the pressure level which corresponds to the value of the second predetermined air pressure is reached, so that excessive air supplied is again discharged in this way.

The invention will be explained below with reference to a drawing, in which:

Fig. 1 shows a diagrammatic top view in section of a first exemplary embodiment of the respiration air supply unit according to the invention;

Fig. 2 likewise shows a diagrammatic top view in section of a second exemplary embodiment of the respiration air supply unit according to the invention;

Fig. 3 shows a diagrammatic side view in section of a third exemplary embodiment of the respiration air supply unit according to the invention; and

Fig. 4 shows a diagrammatic side view in section of a fourth exemplary embodiment of the respiration air supply unit according to the invention.

Fig. 1 indicates by 1 a respiration air supply unit according to the present invention. This unit comprises a housing 2 with an air inlet 3, which in use is connected by way of a suitable hose (not shown) to a compressed air cylinder (not shown either) .

The air inlet 3 comprises a valve seat 4, against which a shut-off element 5 in its neutral position presses under the influence of the pressure of a valve spring 6. The force produced by the valve spring 6 is so great in this case that said shut-off element 5 is held pressed against the valve seat 4, even when the air supply is connected to the air inlet 3.

The unit also comprises a pressure-sensitive membrane 7 which is fixed in a suitable manner in the housing 2. A hardened, for example circular, part 8 is present in the centre of the membrane 7, which part is provided with one or more openings 9. The openings 9 are covered by a spring-loaded shut-off element 10.

The housing 2 comprises an outlet opening 11 which is provided with a mouthpiece 12. Depending on the air pressure prevailing in the housing 2, the membrane 7 undergoes a certain deflection, which deflection, as a result of the changing pressure in the housing 2 , varies with the breathing of a user. The to and fro deflection of the membrane 7 is transmitted by way of the hardened part 8 of the membrane 7 to an arm 13, which arm, through a suitable transmission, regulates the degree of closure of the shut-off element 5 against the valve seat 4 in the air inlet 3. When the user inhales, the reduced pressure in the space 14 of the housing 2 , which space is separated from the remainder of the housing by the membrane 7 and into which at least the air inlet 3 and the outlet opening 11 open, will cause the membrane 7 to move slightly in the direction of the mouthpiece 12, taking with it the arm 13, which in turn causes the shut-off element 5 to come away slightly from the valve seat 4, as a result of which

compressed air can flow out of the air inlet 3 by way of the space 14 and the outlet opening 11 into the mouthpiece 12. When the user inhales and when air is supplied through the air inlet 3, a slight vacuum will continue to prevail in the space 14. The membrane 7 will consequently continue to maintain a deflection, while during thiε phase also no air will escape through the openings 9 in the hardened part 8 of the membrane 7 , partly due to the fact that the openings 9 have been shut off by the spring-loaded shut-off element 10.

When the user exhales now, or when the user stops inhaling, the membrane 7 will move away from the mouthpiece 12, and the shut-off element 5 will be driven against the valve seat 4 through the force exerted thereon by the valve spring 6, so that the air supply through the air inlet 3 is shut off. The raised pressure in the space 14 when the user exhales causes the spring-loaded element 10 to be pressed away from the openings 9, so that the exhaled air can be discharged through these openings and through the outlets 15. When the user stops exhaling, the openings 9 will be shut off again by the spring-loaded element 10.

The way in which the respiration air supply system according to the invention operates will now be explained when it is acting as a resuscitation apparatus for administering air in emergencies. For this purpose, the unit according to the invention is provided with a control button 16, which for adminiεtering air to a victim has to be pressed relative to the housing 2 against the pressure of a first coil εpring 17. The dimenεionε of the control button 16 are preferably such that it can be presεed by, for example, the palm of the hand.

Preεsing the control button 16 also causes the second coil spring 18 and a pressure ring 19 to move towards the membrane 7. The pressure ring 19 will come to rest against the spring-loaded element 10. The spring- loaded element 10, which fulfils a valve function for the openings 9, consequently becomes heavier, so that the pressure in the space 14 at which the openings 9 are opened

Finally, Figure 1 shows a purge button 21 which operates independently of the control button 16, and which can be pressed against the force of a third coil spring 22, in order to interact with a stop element 23 and make the membrane 7 undergo such a deflection that the shut-off element 5 comes away from the valve ring 4 and air can flow through the air inlet 3 into the space 14. When the purge button 21 is pressed, the spring-loaded element 10 is not loaded by the pressure ring 19. The function of the purge button is underwater removal of water from the space 14 and the mouthpiece 12 when the mouthpiece has been out of the mouth. The purge button is known from the prior art.

Fig. 2 shows a second embodiment of the respiration air supply system according to the invention. The exemplary embodiment of Fig. 2 is similar to that of Fig. 1, and the corresponding parts have the same reference numbers. The embodiment of Fig. 2 differs from that of Fig. 1 in that the housing 2 has an additional air outlet 24 which is provided with an outlet valve 25. If the openings 9' are blocked by the pressure ring

19' and the spring-loaded element 10', the outlet valve 25 will allow air through from the space 14 when the pressure in said space reaches the same value as that at which in Fig. 1 the spring-loaded element 10 loaded by the spring 18 and pressure ring 19 opens the openings 9. If the second coil spring 18 ' is made heavier than the corresponding spring 18 from the embodiment of Fig. 1, when the control button 16 ' is operated the pressure ring 19 ' will be pressed in such a way against the spring-loaded element 10 ' that when the pressure in the space 14 increaseε the outlet valve 25 alwayε opens before the spring-loaded element 10' loaded by the spring 18 ' and pressure ring 19 ' opens the openings 9". Otherwise, this embodiment of the respiration air supply unit according to the invention works in the same way as that of Fig. 1.

The principle of the embodiment of Fig. 2 of the respiration air supply unit according to the invention, namely two outlet valves disposed parallel in the housing 2 , in the case of which the discharge of air from the space

example, pressing a rubber surface at least partially surrounding the housing 2 against the pressure of a resilient element, and thus making the pressure-sensitive membrane move a desired diεtance, as a result of which the outlet valve opens.

In the four embodiments of the respiration air supply system according to the invention discussed above the outlet valves and outlets are accommodated in the housing; however, when used in so-called "full-face masks" they can also be incorporated in the mask, so that the air discharge is, for example, by way of an outlet valve and outlet provided below the user's mouth.

Although in the embodiments described above it is assumed that this is a respiration air supply unit for use in skin diving, a respiration air supply unit according to the invention can also be used advantageously in a compressed air mask such as that in use in, for example, the fire service. There again, if an unconεcious victim is found in a smoke-filled room it is possible to provide him with air directly by means of a respiration air supply unit according to the invention, without the victim first having to be removed from the room concerned. The fact that air iε adminiεtered earlier can thus prevent more seriouε consequences for the victim. Yet another application can be found in an artificial respiration apparatus which is used by, for example, doctors, First Aiders or ambulance personnel in order to resuscitate a patient or victim. Manual resuscitation by meanε of a squeeze balloon then becomeε a thing of the past.

If for the last application the respiration air supply unit is equipped with a pneumatic or electronic control unit, the artificial respiration could be carried out automatically, at set intervals.