EP3784562A1

EP3784562A1 - Breathing apparatus for scuba diving with semi-closed circuit gas recycling

Info

Publication number: EP3784562A1
Application number: EP19718725.5A
Authority: EP
Inventors: Bernard GIAI-CHECA; Nicolas Peyron; Stéphane RAINAUT
Original assignee: La Spirotechnique Industrielle et Commerciale
Current assignee: La Spirotechnique Industrielle et Commerciale
Priority date: 2018-04-24
Filing date: 2019-04-24
Publication date: 2021-03-03
Also published as: US20210078683A1; WO2019206963A1; US11993353B2; FR3080358B1; FR3080358A1

Abstract

The subject matter of the invention is a breathing apparatus (1) for scuba diving with semi-closed circuit gas recycling comprising a breathing loop (2). The breathing loop (2) comprises a breathing bag (3), intended to be supplied by at least one gas tank (4), and a recycling chamber (61). The gas tank is connected to at least one input of the breathing bag by a first pipe (11) and a second pipe (12) respectively comprising a demand regulator (110) and a fixed nozzle (120) configured to respectively deliver a first supply and a second supply of gas to the breathing bag (3). Advantageously, the apparatus comprises a third pipe (13) comprising a gas flow regulator (130) configured to deliver, at a variable mass flow, a third supply of gas to the breathing bag (3), and at least one diving condition sensor configured to measure a physiological parameter of the diver or the depth. The appliance is advantageously configured to vary the variable mass flow as a function of data from the sensor for optimising the gas consumption.

Description

'SCUBA breathing apparatus with gas recirculation in semi-closed circuit'

TECHNOLOGICAL DOMAIN

The present invention relates to a breathing apparatus with gas recirculation. It finds at least one particularly advantageous application in the field of underwater diving breathing apparatus with gas recirculation semi-closed circuit.

BACKGROUND

The breathing apparatus with gas recycling or rebreather is mainly used for scuba diving. It allows a substantial saving of gas compared to a breathing apparatus operating in open circuit (usually designated by the acronym OC of the English Open Circuit).

A rebreather typically includes a breathing bag in which the diver breathes. The gas composition in the breathing bag is mainly the result of a mixture of fresh gas inputs and recycled gas inputs.

The recycled gas is generally obtained by filtration or purification of the gases exhaled by the diver. This filtration is intended in particular to trap all or part of the carbon from the CO 2 contained in the exhaled gas, in order to release molecular oxygen (O 2). After filtration, the gas thus "recycled" can be reinjected into the breathing bag. The fresh gas always contains oxygen (02), a variable part of which is metabolized by the diver according to his physiological needs. The fresh gas may also contain one or more diluents such as nitrogen (N2).

The supply of fresh gas can be done in different ways. In particular, there are the recyclers operating in semi-closed circuit (SCR acronym of "semi-closed rebreather" in English terminology) and the recyclers operating in closed circuit (CCR acronym for "closed-circuit rebreather" according to the English terminology). Saxon).

The present invention relates in particular to recyclers operating in semi-closed circuit (SCR).

In the case of an SCR rebreather, a usually overoxygenated gas is injected into the breathing loop with a constant mass flow rate. This flow rate is calculated to meet, within acceptable physiological limits, all breathing regimes and all the profiles of divers.

FIG. 1 shows such a rebreather comprising a breathing bag 3 fed with gas by an on-demand regulator 110 (DD) and by a nozzle 120 delivering a supply of fresh gas with a constant mass flow rate (fixed nozzle). The breathing bag is also fed with recirculated air from a recycling chamber 61. This recycling chamber 61 receives exhaled air from the plunger, traps the carbon dioxide from the exhaled air, typically in a lime cartridge and delivers recycled air.

During the dive, the excess gas, taken as being the difference between the quantity of gas injected into the breathing bag 3 and the quantity of gas consumed by the plunger, is evacuated via a pressure relief valve 31.

A disadvantage of such a solution is the waste of this surplus gas not consumed.

In order to optimize the supply of fresh gas and to limit waste, document US 6408847 B1 discloses, for example, an SCR recycler of which part of the fresh gas supply varies according to the inspiration intensity of the diver. Such a solution includes a valve mounted on the demand regulator, and mechanically controlled by a pressure sensitive valve located on the inspiratory side of the breathing loop. If the diver inhales deeply (so as to create a sufficient depression), the pressure sensitive valve actuates, by a mechanical system, the valve mounted on the regulator on demand. In response, it opens and releases an additional gas supply.

In practice, it turns out that if the valve is faulty, the supply of oxygen becomes insufficient, leading to a risk to the diver. This solution is therefore not sufficiently reliable in terms of security.

Several accidents have been observed with this type of solution. Due to these security issues, the use and development of this solution has remained extremely limited.

To overcome this drawback, other solutions include a sensor to assess the oxygen content in the respiratory bag. Depending on the measured oxygen content, the system injects pure gas (0 ₂ ) into the breathing bag to maintain pressure substantially constant oxygen at a fixed set point. In practice, this solution is also problematic in terms of safety since a failure of the oxygen sensor immediately endangers the diver.

The majority of the solutions proposed to increase the reliability of these recyclers consist of multiplying the number of sensors and pooling their measurements. This reduces the risk that a failure of one of the sensors interrupts the oxygen supply or on the contrary wastes a large amount of oxygen. These solutions have the main disadvantage of increasing the complexity of the system, which leads to increase its cost and make more difficult maintenance.

An object of the present invention is to overcome at least some of the disadvantages mentioned above.

More particularly, the invention aims to provide a semi-closed recirculating breathing apparatus having an improved level of safety for the diver and offering a satisfactory diving time.

ABSTRACT

A first aspect of the invention relates to a submarine gas recirculating diving breathing apparatus in a semi-closed circuit intended to be carried by a plunger, comprising a breathing loop intended to be connected to at least one gas reservoir, the breathing loop comprising:

at least one nozzle intended for the diver and enabling the diver to breathe in the breathing loop,

at least one recycling chamber connected to an outlet of the nozzle and intended to recycle at least a portion of an exhaled gas by the plunger so as to supply a recycled gas, said chamber being configured to receive a filtration device of expired gas, and

at least one breathing bag having an outlet connected to an inlet of the mouthpiece, an inlet connected to an outlet of the recycling chamber and at least one inlet intended to be connected to at least one outlet of the at least one reservoir gas, the breathing bag being configured to allow the mixture within it recycled gas from the recycling chamber and at least one gas supply, said fresh gas from the at least one gas tank.

The respiratory apparatus further comprises a plurality of conduits allowing connections in parallel between at least one inlet of the breathing bag and the at least one gas reservoir, preferably a plurality of outlets of the at least one gas reservoir, at least one first conduit of said plurality of ducts being equipped with a first nozzle called fixed nozzle configured to deliver at a constant volume flow rate and preferably at a constant mass flow rate a first supply of fresh gas to the breathing bag.

Advantageously, the respiratory apparatus further comprises: A second conduit of said plurality of conduits. The second duct is equipped with a gas flow regulator. This gas flow regulator is configured to deliver at a variable volume flow rate and preferably at a variable mass flow rate a second supply of fresh gas to the breathing bag.

at least one diving condition sensor, configured to measure at least one dive condition parameter taken from a physiological parameter of the diver and the pressure of the water surrounding said apparatus.

The breathing apparatus is advantageously configured to control the gas flow regulator so as to vary said variable volume flow rate and preferably said variable mass flow rate at least based on data relating to said at least one diving condition parameter.

The diving breathing apparatus according to the invention thus makes it possible to modulate the supply of fresh gas via the nozzle with a variable volume flow rate. This modulation of gas supply depends on a data of the diving condition sensor and advantageously makes it possible to optimize the consumption of gas (fresh air) as a function of a physiological parameter of the plunger or of the surrounding hydrostatic pressure. The waste of fresh air is thus reduced and the duration of the dive lengthened. Diving comfort is also increased. In addition, such an apparatus comprising three ducts offers a level of safety greater than or equal to that of a conventional semi-closed apparatus comprising one or two ducts, in the event of damage to one of said ducts. Indeed, a risk analysis envisaging different cases of damage on these ducts makes it possible to show that the probability of occurrence of a critical situation for such an apparatus is reduced with respect to a semi-closed respiratory apparatus. classic. This risk analysis is detailed later.

According to an advantageous and preferred possibility, the at least one diving condition sensor is a physiological sensor and preferably a ventilatory frequency sensor.

Such a sensor advantageously allows to account for the effort provided by the diver at each moment of the dive. Thus, the gas consumption is optimized according to the effort of the diver.

The at least one dive condition sensor may further include a depth or pressure sensor configured to measure a dive depth.

According to a preferred embodiment, the breathing apparatus is configured so that the gas pressure at the inlet of the fixed nozzle is constant, for example equal to 15 bars. The breathing apparatus is preferably configured so that the gas pressure at the inlet of the gas flow regulator is constant, for example equal to 15 bar.

According to this embodiment, the density of the gas entering the fixed nozzle and / or the gas flow regulator is constant, and the amount of oxygen contained in this gas is advantageously constant, regardless of the surrounding hydrostatic pressure. In this case, the mass flow delivered at the outlet of the fixed nozzle and / or the gas flow regulator is advantageously proportional to the corresponding volume flow rate. According to a particularly advantageous possibility, the respiratory apparatus further comprises an electronic control module. This electronic module is preferably configured to electronically control the gas flow regulator so as to vary the variable volume flow at least according to said data relating to said dive condition parameter.

This electronic control of the variable volume flow advantageously makes it possible to avoid the use of mechanical solutions requiring, for example, manipulation on the part of the plunger (change of fast connectors in order to change the type of nozzle, manual adjustment).

A second aspect of the invention relates to a kit for equipping a half-closed circuit scuba diving breathing apparatus to be worn by a diver.

This kit includes at least:

a gas flow regulator configured to deliver at a variable volume flow rate and preferably at a variable mass flow rate a second supply of fresh gas via at least one duct connected to the breathing bag and to the at least one gas reservoir of the apparatus; respiratory,

at least one diving condition sensor, configured to measure at least one dive condition parameter taken from a physiological parameter of the diver and the pressure of the water surrounding said apparatus, said at least one sensor being configured to be carried by at least one of the apparatus, the kit and the diver,

an electronic control module configured to control the gas flow regulator so as to vary said variable volumetric flow rate and preferably said variable mass flow rate at least as a function of a datum relative to said at least one dive condition parameter.

BRIEF INTRODUCTION OF FIGURES

Other features, objects and advantages of the present invention will appear on reading the detailed description which follows, and with reference to the appended drawings given as non-limiting examples and in which:

Figure 1 shows a conventional mechanical semi-closed rebreather from the prior art; Figure 2 shows a semi-closed rebreather according to a non-limiting embodiment of the invention;

FIG. 3 illustrates a semi-closed rebreather according to one embodiment of the invention carried by a diver.

FIG. 4 illustrates an exemplary kit according to the invention.

DETAILED DESCRIPTION The invention according to its first aspect comprises in particular the following optional features that can be used in combination or alternatively:

According to one embodiment, the at least one sensor is a ventilatory frequency sensor.

According to one embodiment, the ventilatory frequency sensor is positioned on a portion of the breathing loop located between the inlet of the mouthpiece and the outlet of the breathing bag. This reduces the humidity to which the sensor is exposed. Indeed, if it was disposed between the tip and the recycling chamber, or in the latter, the sensor would be subjected to a higher humidity. It turned out that the reliability of these sensors is degraded by the presence of too high humidity. This embodiment thus makes it possible to further improve the reliability, and consequently the safety, of the apparatus according to the invention.

In one example, the at least one dive condition parameter is a physiological parameter of the diver. This physiological parameter may for example be the ventilatory frequency of the plunger and / or its heart rate and / or the saturation / the oxygen level in the blood of the plunger. Thus, the at least one dive condition sensor is configured to measure the diver's breath rate and / or heart rate and / or saturation / oxygen level in the diver's blood. This is a direct death. This parameter or data relating to this parameter is then sent to the electronic control module which controls the gas flow regulator.

According to one embodiment, the apparatus further comprises a demand regulator equipping an additional conduit of said plurality of conduits. The on-demand regulator is configured to deliver additional fresh gas input to the breathing bag.

According to one embodiment, a manual injector can replace the demand regulator to deliver to the breathing bag the supply of additional fresh gas from the at least one gas reservoir.

According to one embodiment, the first and second ducts feed two separate inputs of the breathing bag. According to an alternative embodiment, the first and second conduits supply the same inlet of the breathing bag. For example, a "Y" duct makes it possible to collect fresh gas inputs from the first and second nozzles and to supply a single inlet of the breathing bag. This alternative embodiment makes it possible to reduce the number of entries of the breathing bag and the number of ducts. It simplifies the device and improves its robustness.

According to one embodiment, the first and second ducts are fed by two separate outputs of the breathing bag. According to an embodiment alternatively, the first and second ducts are fed by the same outlet of the breathing bag. For example a conduit in "Y" allows to feed the first and second. This alternative embodiment makes it possible to reduce the number of tank outlets and the number of ducts. It simplifies the device and improves its robustness.

Likewise, the additional conduit equipped with the optional on-demand keeper, when present, may possibly be connected to the same input and / or the same output as at least one of the first and second conduits.

According to one embodiment, the recycling chamber comprises a filtration device such as a soda lime cartridge.

According to one embodiment the nozzle is configured to cooperate with the mouth of the plunger.

According to one embodiment the tip is in the form of a face mask taking both the mouth and the nose of the plunger.

According to one embodiment, the apparatus comprises a physiological sensor configured to measure at least one physiological parameter of the plunger and a depth sensor for measuring the pressure of the water surrounding said apparatus, and the apparatus is configured to control the regulator of gas flow so as to vary the variable volume flow at least according to the physiological parameter of the plunger and the pressure.

According to one embodiment, the gas flow regulator comprises a second nozzle having a variable section so as to deliver the second variable volume flow supply.

According to an alternative embodiment to the previous embodiment, the gas flow regulator comprises an intermittent opening valve and a nozzle having a fixed section, said nozzle being coupled to said valve so as to deliver the second variable volume flow rate delivery. and preferably variable mass flow.

According to one embodiment, the apparatus is configured so that the variable volume flow rate and preferably the variable mass flow rate delivered by the gas flow regulator is respectively less than or equal to the constant volume flow rate and preferably to the constant mass flow rate delivered. by the fixed nozzle.

This configuration makes it possible to deliver at least half of the total volume flow rate by the first constant volume flow nozzle, and at most half of the total volume flow rate through the second variable volume flow nozzle. A gas saving of 50% is thus advantageously possible under minimal effort of the plunger (static diving) while keeping an intake of fresh air acceptable for the plunger in case of malfunction of the second nozzle. This solution thus offers an improved level of safety since even in the event of failure of the variable volume flow nozzle, the breathing bag is supplied with sufficient fresh gas so that the diver is not in danger. He can then for example, finishing the dive with a satisfactory level of comfort, or returning to the surface, or heading to other divers.

According to one embodiment, the apparatus is configured so that the constant volumetric flow D _1V delivered by the fixed nozzle and the variable volume flow rate D ₂ v delivered by the gas flow controller are such that k ₁ ^* (D ₁ v + D2v) £ D2v £ k2 ^* (D ₁ v + D ₂ v), with ki = 0.1 and k ₂ = 0.9, preferably with ki = 0.2 and k ₂ = 0.8, and preferably with ki = 0.3 and k ₂ = 0.7.

According to one embodiment, the fixed nozzle is configured to deliver the first fresh gas supply from a first pressurized gas tank and the gas flow controller is configured to deliver the second fresh gas supply from a second gas tank. under pressure.

This configuration advantageously makes it possible to separate the sources of gas supply, which reduces the probability of occurrence of a total rupture of gas supply (case of simultaneous failures on each of the first and second nozzles). This embodiment thus makes it possible to further improve the reliability, and consequently the safety, of the apparatus according to the invention.

According to one embodiment, the apparatus comprises the at least one gas reservoir. According to one embodiment, the gas flow regulator is formed of at least and preferably only of:

a fixed nozzle configured to deliver at a constant volume flow rate and preferably at a constant mass flow rate a first supply of fresh gas to the breathing bag,

- A solenoid valve configured to vary in time the flow of said fresh gas supply so as to deliver at variable volume flow rate and preferably variable mass flow rate the second supply of fresh gas to the breathing bag.

According to one embodiment, the solenoid valve and the fixed nozzle of the gas flow regulator are connected in series.

In the remainder of the description when it is stated that a member A is directly connected to a member B, this means that there are no other members between A and B, unless otherwise indicated.

According to one embodiment, the outlet of the nozzle is directly connected to the inlet of the recycling chamber.

According to one embodiment, the outlet of the recycling chamber is directly connected to an inlet of the breathing bag.

According to one embodiment, an outlet of the breathing bag is directly connected to an inlet of the nozzle, with the exception of at least one sensor configured to measure the dive condition parameter used to control the gas flow regulator. .

According to one embodiment, a first conduit directly connects a fresh gas reservoir to the breathing bag, with the exception of the fixed nozzle which is disposed on this first conduit. According to one embodiment, a second conduit directly connects a fresh gas reservoir to the breathing bag with the exception of the gas flow regulator which is disposed on this second conduit.

According to one embodiment, a third conduit, which is only optional, directly connects the fresh gas reservoir to the breathing bag, with the exception of the demand regulator which is disposed on this third conduit.

The invention according to its second aspect comprises in particular the following optional features that can be used in combination or alternatively:

According to one embodiment, the at least one diving condition sensor is a physiological sensor.

According to one embodiment, the physiological sensor is a ventilatory frequency sensor.

According to one embodiment, the ventilatory frequency sensor is configured to be positioned on the breathing loop between the inlet of the nozzle and the outlet of the breathing bag.

According to one embodiment, the kit further comprises a depth sensor configured to be connected to the electronic control module so as to enable the electronic control module to control said variable volumetric flow rate as a function of at least one datum of said sensor. depth.

In the following description and claims, the following terms mean:

- sonic nozzle: the sonic nozzle is a calibrated orifice in which the flow velocity of the gas is greater than or equal to the sonic velocity of this gas to the right of the minimum passage section of the orifice (sonic or supersonic flow).

- volume flow rate: the volume flow rate D _v of a gas passing through an orifice or a nozzle of section S at a speed v is: D _v = v. S. In the case of a subsonic flow, this flow rate D _v varies as a function of the pressure of the gas upstream of the nozzle and the pressure of the gas downstream of the nozzle. In the case of a supersonic flow, this flow rate D _v varies according to the pressure of the gas upstream of the sonic nozzle only. The volume flow D _v is expressed in L / min in the following.

constant volume flow: a gas that flows through a sonic nozzle of fixed section S at sonic velocity presents a constant volume flow rate for a constant gas pressure upstream of the sonic nozzle.

mass flow rate: the mass flow rate D _M of a gas passing through an orifice or a nozzle of section S at a speed v is: D _M = pv S, where p is the density of the gas.

constant mass flow: a gas that flows through a nozzle of fixed section S at sonic velocity has a constant mass flow rate, if the density of this gas is constant. In In particular, a gas delivered at constant pressure upstream of the sonic nozzle has such a constant mass flow rate.

In the following, a constant mass or volume flow is also called sonic flow.

Constant flow rate is defined as a flow rate which does not change over time (over an observation period greater than 1 minute, preferably greater than five minutes and preferably from a few minutes to a few tens of minutes) of more or less 10 % and preferably plus or minus 5% and preferably plus or minus 2%.

- air equivalent depth: the depth indicated on decompression tables relating to breathing gas mixtures containing nitrogen and oxygen in proportions different from those of air, known as nitrox.

In the following, the terms "orifice" and "nozzle" are used in synonyms. The terms "flow" and "flow" are also used in synonyms.

The terms "gas recirculating breathing apparatus" and "recycler" are used in synonyms.

In the following, the fresh gas is a gas containing oxygen and which has not been recycled by trapping the C0 ₂ exhaled by the user. Thus, the term "fresh" gas is understood as opposed to the term "recycled" gas, the recycled gas being the gas delivered by a recycling chamber after trapping the C0 ₂ exhaled by the user. The fresh gas typically comes from a gas cylinder shipped by the diver. The fresh gas may be fresh air, or a mixture comprising proportions of nitrogen and oxygen different from those of air, such as nitrox, or a mixture comprising nitrogen, water, helium and oxygen such as trimix.

In particular, "fresh air" and "fresh gas" are used in synonyms and can also be understood as "nitrox" and "trimix" or other variants of gaseous mixtures of the trimix type, such as heliox, heliair, the triox for example. Typically, it may be a superoxygenated gas that is to say a mixture containing a percentage of oxygen greater than 21% by volume, for example equal to 30%, 40%, 50% or 60%.

In the remainder of the description and the claims, the term "variable nozzle" means a device for regulating a gas flow rate. For example, a nozzle having an opening of variable and / or adjustable section forms such a device. A nozzle having a fixed section opening associated with an intermittent valve also forms such a device. This device can be simply called "gas flow regulator".

We will now describe the present invention through a preferred but non-limiting embodiment.

With reference to FIGS. 2 and 3, a first embodiment of the invention is a semi-closed circuit scuba diving breathing apparatus 1 comprising a breathing loop 2, a breathing bag 3. The apparatus is configured to be fluidly connected to at least one gas reservoir 4.

The breathing loop 2 comprises a first side said inspiration side 5 and a second side said expiration side 6.

The inspiration side 5 comprises a duct extending from an outlet of the breathing bag 3 to an inlet of the nozzle 56 or a mask intended for the plunger 10 and allows the air inspired by the plunger 10 to be conveyed. The tip can be a mouthpiece inserted partly into the mouth of the diver or be integrated into a face mask taking both the mouth and nose of the diver.

The expiration side 6 comprises a duct extending from an outlet of the mouthpiece 56 or the mask to a breathing bag inlet 3 and serves to convey the exhaled air by the plunger 10.

The expiration side 6 comprises in particular a recycling chamber 61 adapted to receive an expired air filtration device, such as a soda lime cartridge. Such a filter device is configured to trap the carbon dioxide present in the exhaled air, and pass a filtered or purified portion of exhaled air. This part, also called recycled air, is then reinjected into the breathing bag 3. The recycling chamber 61 has an inlet coupled to the outlet of the nozzle 56 or mask and an outlet coupled to the inlet of the breathing bag 3.

The breathing bag 3 is therefore partly fed by the recycled air.

The fresh air supply of the breathing bag 3 is preferably done primarily through a first conduit 12 and a second conduit 13 extending between the at least one gas reservoir 4 and the breathing bag 3.

The breathing bag 3 is therefore advantageously powered by a double main injection of gas in order to optimize the gas consumption of the plunger 10 and the safety of the dive. These advantages are explained in the following.

The first conduit 12 may comprise a first nozzle 120 preferably having a fixed section. A first expander 121 at an outlet of the at least one gas reservoir 4, connected to this first duct 12 upstream of the first nozzle, called the fixed nozzle 120, is configured to deliver gas at the inlet of this nozzle This first regulator 121 corresponds for example to a "first stage" type regulator that is usually encountered on diving cylinders. This type of expansion valve typically allows to relax a gas of 200 bar at 10 or 15 bar. This type of expansion valve is, however, generally controlled by the hydrostatic pressure of the surrounding medium, so as to deliver a relative pressure, for example 15 bar relative to the surrounding hydrostatic pressure. According to a preferred embodiment, this first expander 121 is configured to deliver gas at constant pressure, for example 15 bar, at the inlet of the fixed nozzle 120. In this case, this first expander 121 is not controlled by the pressure hydrostatic surrounding, so as to deliver an absolute pressure, for example 15 bar regardless of the surrounding hydrostatic pressure. This makes it possible to deliver gas having a constant density to the inlet of the fixed nozzle 120. The quantity of oxygen contained in this gas is therefore constant, whatever the hydrostatic pressure.

The fixed nozzle 120 is configured to output the gas at ambient pressure so as to supply the breathing bag 3 with a gas sonic flow with a constant gas volume flow rate D 1 _V , and preferably with a constant gas mass flow rate D _{1 M.} In the nonlimiting example illustrated in FIG. 2, the inlet of the breathing bag 3 fed by the duct 12 carrying the fixed nozzle 120 is referenced 122.

The volume flow rate of constant gas D 1 _V can be between 0 and 40 liters per minute, preferably between 0 and 30 liters per minute and even more preferably between 0 and 20 liters per minute.

The second conduit 13 may comprise a gas flow regulator 130. The gas flow regulator 130 preferably comprises:

Or a second nozzle preferably having a variable section.

That is to say a fixed nozzle 136, that is to say a nozzle of fixed section, connected to a valve 155 allowing the passage of the gas intermittently. It may for example be a solenoid valve.

Or a combination of a solenoid valve and a valve 155 permitting the passage of gas intermittently.

A second expander 131 at the level of the at least one gas reservoir 4, connected to this second duct 13 upstream of the gas flow regulator 130, is configured to deliver gas at the inlet of this gas flow regulator 130. This second regulator 131 may be a "first stage" type regulator. Advantageously and similarly to the operation of the first expander 121 detailed above, this second expander 131 is configured to deliver gas at a constant pressure, for example 15 bar, at the inlet of the gas flow regulator 130.

According to one embodiment, the first and second regulators 121, 131 may be one and the same regulator, so as to simplify the system and make it more robust. The connection between this regulator and the first and second conduits 12, 13 may then include a bypass so as to supply each of the two conduits 12, 13.

The gas flow regulator 130 is configured to deliver the gas supplying the breathing bag 3 with a volume flow rate of variable gas D ₂ v, and preferably with a mass flow rate of gas variable D _2M . In the nonlimiting example illustrated in FIG. 2, the inlet of the breathing bag fed by the duct 13 carrying the gas flow regulator 130 is referenced 132.

The variable volume flow rate of gas D ₂ v is such that D _2min D D _2V D D _2max .

For example, the variable volumetric flow rate of D 2 _V gas can be between 0 and 40 liters per minute, preferably between 0 and 30 liters per minute and even more preferably between 0 and 20 liters per minute.

According to this exemplary embodiment, the gas flow regulator 130 continuously feeds the breathing bag 3 at least for D ₂ v> D 2 _min , without interrupting the supply of fresh gas.

According to an alternative embodiment, the first 12 and second 13 ducts are fed by the same outlet 121 of the gas tank 4, as illustrated in FIG. 4.

According to an alternative embodiment, the first 12 and second 13 conduits feed a same inlet 122 of the breathing bag 3, as shown in Figure 4. For this the first 12 and second 13 ducts are connected; for example in "Y" to a common conduit 123.

These embodiments make it possible to simplify and improve the robustness of the apparatus.

According to one embodiment, the gas flow regulator 130 may consist of a nozzle of variable section called variable nozzle.

According to another embodiment, the gas flow regulator 130 may be constituted by the combination of a fixed nozzle 136 of constant section and a valve 155 or solenoid valve with intermittent opening, punctually interrupting the supply of fresh gas , so as to vary the volume flow D _2V . In this configuration, the flow rate D _2V takes only the values 0 and D _2max. This second supply of fresh gas can thus be delivered to sonic flow, which advantageously makes it possible to accurately evaluate the quantity of oxygen actually delivered. The average supply of fresh gas from this second intake therefore varies according to a cutoff frequency of the solenoid valve for example. This configuration also reduces the cost of the system. This alternative embodiment is illustrated in FIG.

The following description refers to the embodiment in which the gas flow regulator 130 comprises a nozzle of variable section. Nevertheless, all the embodiments, features and advantages described below can be combined with the embodiment in which the gas flow controller 130 includes a fixed or variable nozzle 136 connected to an intermittent valve 155 such as a solenoid valve. The reference numeral 130 is therefore used for the gas flow regulator 130, regardless of its embodiment, and the expression "variable nozzle 130" may be replaced by the expression "gas flow regulator 130".

According to an optional embodiment, the breathing bag 3 can be supplied with fresh air through an additional conduit 1 1 extending between the at least one gas reservoir 4 and the breathing bag 3. This additional conduit 11 can be configured to deliver additional fresh gas supply via a Demand 1 10 demand expansion valve. This demand regulator 1 10 can be controlled manually by the plunger 10 (it can then be called an injector), as needed, and / or can be triggered automatically, for example during a rapid descent, to deliver a supplement of fresh air in the 3. Such a demand regulator 1 10 is perfectly conventional and widely known in the field of diving. It typically corresponds to a "second stage" type regulator found on open-circuit breathing apparatus (OC), the air suction being connected to the breathing bag in the context of the invention. According to an alternative embodiment, the supply of additional fresh gas is delivered via a manual injector alone or coupled to an on-demand regulator 1 10.

The reference 1 10 corresponds either to a demand regulator or a demand regulator coupled to a manual injector or a manual injector alone.

Advantageously, the breathing bag 3 is fed continuously through the fixed nozzle 120, and in a variable manner through the variable nozzle 130. The total volume flow D _N of gas delivered to the breathing bag 3 is written D _N = D _1V + D _2V .

Advantageously, the variation of the flow rate D ₂ v of the variable nozzle 130 depends on a physiological need of the plunger 10.

According to a preferred embodiment, the respiratory apparatus 1 comprises an electronic control module 7 and a first sensor 51, referred to as a physiological sensor, configured to measure a physiological parameter of the plunger 10.

The physiological sensor 51 is preferably a respiratory rate sensor. It may be located on the inspiration side 5 of the breathing loop 2, and is preferably configured to minimize the pressure drop in the breathing loop 2. Such a sensor may for example be based on the measurement of a speed of movement of the breathing loop 2. a heated gas bubble. Thus, the sensor directly measures the respiratory rate. This sensor does not depend on a mechanical device that allows or not the gas supply. Thus, the sensor according to the invention is not a demand regulator that allows the gas supply. The accuracy and safety of the device are greatly improved.

The physiological parameter measured, in this example the measured respiratory rate, can then be transmitted to the electronic control module 7 in real time. The electronic control module 7 is configured to adjust the variable flow rate D _2V by means of a microcontroller controlling the variable nozzle 130 according to at least the measured physiological parameter, in this example of the measured respiratory rate. Thus, the variable nozzle 130 is controlled by the device 1 and more precisely by a microcontroller.

The variable nozzle 130 is configured to remain open if it is no longer powered, for example if the electronic module is not activated (button ON / OFF not actuated) or if the battery is discharged, or in case of failure of the electronic control module 7 and / or the microcontroller. This further enhances the safety of the respiratory system. According to an alternative possibility, the physiological sensor 51 may be a heart rate sensor. In this case, the sensor is for example fixed on the thorax or the wrist of the plunger.

According to an alternative possibility, the physiological sensor 51 may be a sensor for oxygen saturation in the blood. In this case, the sensor is for example fixed on the thorax or the wrist of the plunger.

Alternatively, the respiratory apparatus 1 may comprise a plurality of identical sensors to increase the reliability of the assembly by redundancy.

Alternatively, the respiratory apparatus 1 may comprise a plurality of different types of sensors (eg respiratory rate sensor and heart rate sensor). This makes it possible to evaluate more precisely the amount of fresh air to be supplied to the breathing bag. It also helps to further enhance the safety of the respiratory system. Thus, the at least one diving condition sensor is configured to measure at least one of the following parameters: the ventilatory frequency of the diver, his heart rate, the saturation / the oxygen level in the diver's blood. This is a direct death. This parameter or data relating to this parameter is then sent to the electronic control module which controls the gas flow regulator.

According to one embodiment, the total flow rate D _N of gas therefore depends on the measured respiratory rate, via the variable nozzle 130 delivering D ₂ v, and thus meets a need for oxygen on the part of the plunger 10.

The variable flow D ₂ v is preferably zero for a respiratory rate measured below a first RV-i threshold corresponding to a minimum effort of the diver 10. Statistically, the respiratory rate of a diver is less than 10 breaths per minute. minute in situations of minimal effort, such as a static dive or during a decompression stop.

Advantageously, for a measured respiratory rate less than RV-i with for example RV-i = 10 breaths per minute, the variable flow D _2V can be adjusted electronically so that D _2V = 0 L / min. In this case, only the first nozzle 120 with constant volume flow supplies the breathing bag 3 with gas (D _N = D _1V ). A saving of gas can thus be achieved and the duration of the dive is lengthened. Moreover, the respiratory comfort of a breathable diver in the apparatus 1 becomes greater than that of a breathing diver in a conventional rebreather comprising a breathing bag fed only steadily, said breathing bag being then supercharged with gas in a such a situation of minimal effort.

The variable flow D 2 _V is preferably maximum for a respiratory rate measured above a second threshold RV ₂ corresponding to an intense effort of the plunger 10. Statistically, the respiratory rate of a plunger is greater than 20 breaths per minute when situations of intense effort, such as diving into the water or working. The breathing comfort of a breathable diver in the apparatus 1 may also be greater than that of a breathable diver in a conventional rebreather comprising a bag respiratory force fed only constantly, said breathing bag being then underfed gas in such a situation of intense effort.

For a measured respiratory rate between RV-i and RV ₂ , the variable flow rate D ₂ v may be equal to an average flow rate (D _2min + D _2max ) / 2, or may vary continuously as a function of the measured respiratory rate.

According to one possibility, at least half of the total volume flow D _N can be delivered by the first nozzle 120 with a constant volume flow rate D _1V , and at most half of the total volume flow rate D _N can be delivered by the second flow nozzle 130 voluminal variable D _2V , so that 0 <

D ₂ V £ D-iv and D _2max = D-iv-

A gas saving of 50% is thus advantageously possible in a situation of minimal effort of the plunger 10. This compromise also makes it possible to keep an intake of fresh air acceptable for the plunger 10 in the event of malfunction of the second nozzle 130.

This double supply of fresh air of the breathing bag 3 by the fixed nozzle 120 and the variable nozzle 130 thus optimizes the gas consumption by reducing waste and increasing the comfort of the diver 10 during the dive.

Another advantage is the reduction of the amount of gas released by the pressure relief valve 31 of the breathing bag 3, which increases the visual and acoustic discretion during the dive. According to an advantageous possibility, additionally or alternatively to the physiological sensor, the apparatus 1 comprises a depth sensor 52 or surrounding pressure connected to the electronic control module 7. The electronic control module 7 can be configured to adjust the volume flow rate D total _N as a function of depth measured _my P by the depth transducer 52. This D _N of adjustment is made by means of the variable nozzle 130 permitting variation of _2V D.

In particular, the total flow D _N can be reduced in a so-called deep diving zone, for a depth greater than a limit depth P _Nm, for example equal to 18 m. The partial pressure of oxygen P0 ₂ in the gas increases with the depth (Dalton's law), so that from the limiting depth P _Mm , a decrease of the total flow D _N can be realized to compensate for the increase in P0 ₂ . This decrease in the total flow rate D _N as a function of the depth measured, for P _mes > P _üm , also makes it possible to save gas.

This decrease in the total flow D _N causing a decrease in P0 _{2 also} makes it possible to limit the risk of hyperoxic crisis, which becomes important for a P0 ₂ > 1, 6 bar.

For security, the electronic control module 7 is preferably configured to limit the decrease in the total flow rate D _N so as to maintain an oxygen partial pressure P0 ₂ greater than 1 bar and / or greater than a partial pressure of oxygen at the equivalent air depth. In this way the plunger 10 always has the possibility of following an air decompression table during a recovery to the surface.

The flow D _1V is preferably delivered via mechanical elements only, such as the first constant pressure regulator and the fixed nozzle 120. The flow D _1V is therefore controlled purely mechanically. The flow rate D ₂ v is preferably electronically controlled by the electronic control module 7.

The double injection of gas into the breathing bag 3 is therefore preferentially done by a so-called mechanical injection and by a so-called electronic injection.

According to one possibility, the proportion of mechanical injection and electronic injection can be chosen so as to optimize the general operation of the respiratory apparatus 1.

This choice may result for example from a risk analysis.

The ratio of flow rates L = D ₂ v / D _N can thus be adjusted between 0 and 1 as a function of the proportion of mechanical injection and desired electronic injection.

For L = 0, the operation of the apparatus 1 corresponds to that of a conventional semi-closed mechanical recycler whose entire injection is governed by a fixed nozzle.

For L = 1, the operation of the apparatus 1 corresponds to a recycler whose entire flow is electronically controlled.

The risk analysis relating to a malfunction of the device 1 in the event of damage at the D 1 _V and / or D 2 _V flow rates shows that:

In the case where the fixed nozzle 120 operates normally and the variable nozzle 130 does not work and remains open (damage case No. 1), the injection is constant and has a maximum total flow D _N = D _1V + D _2max ,

The apparatus 1 then operates in a manner similar to a conventional mechanical semi-closed rebreather.

In the case where the fixed nozzle 120 operates normally and the variable nozzle 130 does not work and remains closed (in case of damage No. 2), the injection is constant and has a minimum total flow D _N = D _1V . The diver 10 is not in danger and can for example finish his dive, or return to the surface, or go to other divers, minimizing his efforts.

The choice of the ratio L can make it possible to favor a gas injection by mechanical injection at the flow rate D _1V , rather than the injection of gas by electronic injection at the flow rate D _2V . For L <0.5 the diver 10 can continue his dive with a satisfactory level of comfort in this case of damage n ° 2.

In the case where the fixed nozzle 120 does not work and the variable nozzle 130 operates normally (in case of damage No. 3), the injection is variable and has a total flow D _N = D _2V .

The choice of the ratio L can make it possible to favor an injection of gas by electronic injection at the flow rate D _2V , rather than the injection of gas by mechanical injection at the flow rate D _1V . For L> 0.5 the diver 10 can continue his dive with a satisfactory level of comfort in this case of damage n ° 3. The probability of occurrence of this case of damage n ° 3 is identical to the probability of occurrence of a plugged nozzle on a conventional semi-closed mechanical device.

In the case where the fixed nozzle 120 does not work and the variable nozzle 130 does not work and remains closed (in case of damage No. 4), there is more main injection and D _N = 0.

This case of failure 4 must be managed by the plunger 10 in the same way as with a conventional semi-closed mechanical rebreather.

According to an advantageous possibility, the fixed nozzle 120 is connected to a first gas tank and the variable nozzle 130 is connected to a second gas tank, so that the supply sources of the two nozzles are separated. The probability of occurrence of the damage case # 4 is then reduced.

The probability of occurrence of a critical situation for such a device 1 is thus reduced vis-à-vis a conventional semi-closed device. This solution therefore offers an improved level of security.

The injection D _N can also be supplemented as required by the demand regulator 1 10 on the conduit 1 1 for example.

This additional injection via the pipe 1 1 preferably delivers the same gas as the main injection by the nozzles. The triggering of the demand regulator 1 10 can be done manually by the plunger 10, and / or automatically, for example during a rapid descent of the plunger 10. This makes it possible to prevent the breathing bag 3 from retracting under the effect of increasing the ambient hydrostatic pressure, the fixed and variable nozzles delivering too little gas to quickly compensate for the increase in ambient hydrostatic pressure.

This regulator on demand 1 10 thus increases the comfort of the diver and allows him to make fast descents but is not necessarily essential.

As illustrated in Figure 2, it will be noted that the first conduit 12 allows the passage of gas from the gas reservoir 4 to the breathing bag 3 passing through only the first nozzle 120 constant volume flow. Preferably, this duct 12 comprises only the first nozzle 120 constant volume flow. In particular, this duct 12 does not include an on-demand regulator. The gas passing through the first nozzle 120 with constant volume flow does not pass through a demand regulator before reaching the breathing bag 3. This considerably improves the safety of the device.

The breathing bag 3 also preferably comprises a pressure relief valve 31 for eliminating excess gas in the breathing loop 2. A second aspect of the invention relates to a kit 20 adaptable on a conventional semi-closed mechanical rebreather. Typically this kit 20 can be mounted on an apparatus such as that illustrated in FIG.

With reference to FIG. 4, this kit 20 comprises at least one so-called variable nozzle 130 configured to deliver a variable volumetric flow rate of gas D ₂ v, a sensor 51, 52 configured to measure a depth or a physiological parameter of the plunger and a module control electronics 7 configured to vary the flow rate D ₂ v of the variable nozzle 130 as a function of at least one data of the sensor 51, 52.

The variable-rate nozzle 130, also designated gas flow regulator 130, may be formed by a solenoid valve 155 associated with a constant-flow nozzle 136. According to one example, such a nozzle 136 is for example similar to a sonic nozzle 120. Variable nozzle 130 may be connected to an auxiliary duct provided separately or included in the kit 20. This auxiliary duct connects the breathing bag 3 and at least one gas reservoir 4 of the conventional semi-closed mechanical rebreather, so as to deliver an auxiliary supply of fresh gas with variable volumic flow rate D _2V .

A Y-link 123 at the inlet and / or outlet of the nozzles 120 and 130 or ducts 12, 13 equipped with the nozzles 120, 130 can make it possible to simplify the connections and to improve the robustness of the apparatus. This allows for example to have only one inlet 124 on the breathing bag to collect the contributions of the nozzles 120 and 130. These Y connections can be provided separately or integrated into the kit 20.

Preferably, it will be noted that in this example also, the conduit 12 allows a supply of the breathing bag 3 by the gas tank 4 by passing only through the first nozzle 120 constant volume flow. In particular, the gas from the gas reservoir 4 does not cross another member such as a demand regulator to reach the breathing bag 3 through the conduit 12 and the first nozzles 120 constant volume flow.

The physiological sensor 51 is preferably a ventilatory frequency sensor, and can be connected to the breathing loop 2 of the conventional mechanical semi-closed rebreather, between the breathing bag 3 and the nozzle 56 intended for the plunger.

In addition to the physiological sensor 51 or as an alternative to the physiological sensor 51, the kit 20 comprises a depth sensor 52 and the electronic control module 7 is configured to vary the flow rate D _2V of the variable nozzle 130 as a function of at least depth sensor data 52.

The depth sensor 52 is preferably integrated in a sealed enclosure 21. This reduces the size of the kit 20 and improve the handling of the kit 20 by the user.

This kit 20 advantageously and at a lower cost of transforming the conventional mechanical semi-closed rebreather into a breathing apparatus according to the first aspect of the invention. As is clear from the detailed description above, the invention provides a breathing apparatus and a robust and particularly reliable breathing apparatus kit. The invention thus greatly improves the safety and comfort of the diver. The invention also makes it possible to extend the duration of the dive with respect to a standard rebreather.

The invention is not limited to the embodiments described above but extends to all embodiments within the scope of the claims.

Claims

1. Apparatus (1) for submarine gas recirculating diving breathing apparatus in a semi-closed circuit to be carried by a plunger (10), comprising a breathing loop (2) for connection to at least one gas reservoir (4), the breathing loop (2) comprising:

at least one nozzle (56) for the plunger (10) and allowing the plunger (10) to breathe in the breathing loop (2),

at least one recycling chamber (61) connected to an outlet of the nozzle (56) and for recycling at least a portion of an exhaled gas by the plunger (10) so as to provide a recycled gas, said chamber ( 61) being configured to receive an expired gas filtering device, and

at least one breathing bag (3) having an output connected to an input of the tip (56), an input connected to an output of the recycling chamber (61) and at least one input for connection to at least one leaving the at least one gas tank (4), the breathing bag (3) being configured to allow the mixing of the recycled gas from the recycling chamber (61) and at least one gas supply therein , said fresh gas, coming from the at least one gas reservoir (4), the apparatus (1) comprising a plurality of conduits allowing connections in parallel between at least one inlet of the breathing bag (3) and at least one gas tank (4), the apparatus (1) comprising:

a first duct (12) of said plurality of ducts, equipped with a first nozzle (120) said fixed nozzle configured to deliver at a constant volume flow rate and preferably at a constant mass flow rate a first supply of fresh gas to the breathing bag (3) ,

an additional conduit (1 1) of said plurality of conduits, equipped with an on-demand regulator (1 10) configured to deliver an additional fresh gas supply to the breathing bag (3),

said apparatus (1) being characterized in that it further comprises at said at least one duct:

a second duct (13) of said plurality of ducts, equipped with a gas flow regulator (130) configured to deliver at a variable volume flow rate and preferably at a variable mass flow rate a second supply of fresh gas to the breathing bag (3) ,

in that said apparatus (1) also comprises at least one dive condition sensor (51) configured to measure at least one dive condition parameter taken from a physiological parameter of the plunger (10) and the pressure of the water surrounding said apparatus (1), and in that,

said apparatus (1) is configured to control the gas flow regulator (130) so as to vary said variable volume flow rate and preferably said variable mass flow rate based at least on a data item relating to said at least one condition parameter Diving.

2. Apparatus (1) according to the preceding claim wherein the at least one sensor is a physiological sensor (51).

3. Apparatus (1) according to the preceding claim wherein the at least one sensor is a ventilatory frequency sensor.

4. Apparatus (1) according to the preceding claim wherein the ventilatory frequency sensor is positioned on a portion (5) of the breathing loop (2) between the inlet of the nozzle (56) and the outlet of the breathing bag (3).

5. Apparatus (1) according to any one of the preceding claims wherein the at least one sensor comprises a depth sensor.

Apparatus (1) according to any one of the preceding claims further comprising an electronic control module (7) configured to electronically control the gas flow regulator (130) so as to vary the variable volume flow rate and preferably the variable mass flow rate at least as a function of said data relating to said diving condition parameter.

7. Apparatus (1) according to any one of the preceding claims comprising at least one physiological sensor (51) configured to measure at least one physiological parameter of the plunger (10) and a depth sensor for measuring the pressure of the surrounding water. said apparatus (1), and wherein said apparatus (1) is configured to control the gas flow regulator (130) so as to vary said variable volume flow rate and preferably said variable mass flow rate at least in accordance with the physiological parameter of the plunger (10) and the pressure.

8. Apparatus (1) according to any one of the preceding claims wherein the gas flow regulator (130) comprises a second nozzle having a variable section so as to deliver the second variable volume flow input and preferably mass flow rate. variable.

Apparatus (1) according to any one of claims 1 to 7 wherein the gas flow regulator (130) comprises intermittent valve (155) and a nozzle (136) having a fixed section, said nozzle (136) ) being coupled to said valve (155) so as to deliver the second variable volume flow supply and preferably variable mass flow.

Apparatus (1) according to any one of claims 1 to 7, wherein the gas flow regulator (130) is formed of at least and preferably only:

a fixed nozzle (136) configured to deliver at a constant volume flow rate and preferably at a constant mass flow rate a supply of fresh gas to the breathing bag (3); - a solenoid valve (155) configured to vary in time the flow rate of said supply of fresh gas so as to deliver, at a variable volume flow rate and preferably at a variable mass flow rate, the second supply of fresh gas to the breathing bag (3), the solenoid valve (155) and the fixed nozzle (136) of the gas flow regulator ( 130) being connected in series.

11. Apparatus (1) according to any one of the preceding claims configured so that the variable volume flow rate and preferably the variable mass flow rate delivered by the gas flow regulator (130) is respectively less than or equal to the constant volume flow rate and preferably at the constant mass flow rate delivered by the fixed nozzle (120).

12. Apparatus (1) according to any one of the preceding claims configured so that the constant volume flow D _1V delivered by the fixed nozzle (120) and the variable volume flow D ₂ v delivered by the gas flow regulator (130). ) are such that k ₁ ^* (D ₁ v + D2v) £ D2v £ k2 ^* (D ₁ v + D ₂ v), with ki = 0.1 and k ₂ = 0.9, preferably with ki = 0.2 and k ₂ = 0.8 , and preferably with ki = 0.3 and k ₂ = 0.7.

Apparatus (1) according to any one of the preceding claims wherein the fixed nozzle (120) is configured to deliver the first fresh gas supply from a first pressurized gas tank and the gas flow controller (130). is configured to deliver the second fresh gas supply from a second pressurized gas tank.

14. A kit (20) for equipping a semi-closed circuit gas diving breathing apparatus to be carried by a plunger (10), the apparatus comprising a breathing loop (2) to be connected to at least one gas reservoir (4), the breathing loop (2) comprising at least one breathing bag (3) having: an outlet connected to an inlet of a mouthpiece (56) allowing the diver (10) to breathe in the breathing loop (2), an inlet connected to an outlet of a recycling chamber (61) of a gas exhaled by the plunger and at least one inlet intended to be connected to at least one outlet of the at least one a gas tank (4), the breathing bag (3) being configured to allow the mixing within it of the recycled gas from the recycling chamber (61) and at least one gas supply, said fresh gas, from at least one gas tank (4),

said at least one gas reservoir (4) being connected to at least one inlet of the breathing bag (3) by at least one conduit comprising: a first nozzle (120) called a fixed nozzle configured to deliver at a constant volume flow rate and preferably at a constant mass flow rate a first supply of fresh gas to the breathing bag (3),

an on demand regulator (110) configured to deliver additional fresh gas input to the breathing bag (3),

the kit (20) comprising at least:

a gas flow regulator (130) configured to deliver at a variable volume flow rate and preferably at a variable mass flow rate a second supply of fresh gas through said at least one duct connected to the breathing bag (3) and to the at least one reservoir of gas (4),

at least one diving condition sensor (51) configured to measure at least one dive condition parameter taken from a physiological parameter of the diver (10) and the pressure of the water surrounding said apparatus (1), said at least one a sensor being configured to be carried by at least one of the apparatus (1), the kit (20) and the plunger (10),

an electronic control module (7) configured to control the gas flow regulator (130) so as to vary said variable volumetric flow rate and preferably said variable mass flow rate at least according to a data item relating to said at least one parameter diving condition.

15. Kit (20) according to the preceding claim wherein the at least one diving condition sensor is a physiological sensor.

16. Kit (20) according to the preceding claim wherein the physiological sensor is a ventilatory frequency sensor.

17. Kit (20) according to the preceding claim wherein the ventilatory frequency sensor is configured to be positioned on the breathing loop between the inlet of the nozzle and the outlet of the breathing bag.

18. Kit (20) according to any one of claims 14 to 16 further comprising a depth sensor configured to be connected to the electronic control module so as to allow the electronic control module to control said variable volumetric flow rate and preferably said variable mass flow rate as a function of at least one datum of said depth sensor.