Respiration apparatus with flow limiter

CA 02393068 2002-07-05 ~ RBSPIRATORY APPARATUS WITH FLOW LIMITBUR The invention relates to breathing apparatus intended to protect people on board an aircraft, and in particular flight crew, against the effects of depressurization at high altitude and / or the appearance of toxic fumes or gases.

More precisely, the invention relates to breathing apparatus with demand and dilution regulator and to regulators for the pressure and flow of respiratory gas.A regulator of pressure and flow of respiratory gas generally comprises, connected to an oronasal mask:

- means for admitting additional gas, generally oxygen or air very enriched in oxygen, and - an ejector for mixing dilution air with the additional gas, connected to a supply outlet of a user , in diluted additional gas.

These breathing apparatuses are supplied, at the level of the admission, with additional gas supplied by pressurized oxygen cylinders, chemical generators or generators by selective absorption and restitution of oxygen known as OBOGS (acronym of the English expression). Saxon on-board generator oxygen system).

'CA 02393068 2002-07-05 2 The regulators deliver a respiratory gas for which the evolution of the enrichment for a given flow rate as a function of the altitude presents an inverted bell shape, that is to say the shape of the curve in full txait in figure 1.

Due to the characteristics of the ejector, the flow of additional gas (oxygen), at low altitude, is much higher than the flow corresponding to the physiological minimum necessary, which increases monotonically as a function of the cabin altitude. (dashed curve in FIG. 1) _ The flow of additional gas (oxygen) delivered to the respiratory system is too high compared to the needs and is the cause of an excessive consumption of additional gas (oxygen).

An aim of the invention is in particular to provide a breathing apparatus with a pressure regulator and a respiratory gas flow rate regulator making it possible to reduce the additional gas flow rate called for.

This object is achieved, thanks to a regulator of the type of that described above comprising, in addition, on the admission of additional gas to the ejector, control means capable of modifying the section of passage of the additional gas to the ejector. ejector; these means can in particular switch the supply of additional gas between several inlet passages CA 02393068 2002-07-05 3 having different sections; for example, one of these passages corresponds to a so-called economic flow and has a smaller section than that of the other passage called full flow.

Indeed, the passage of smaller section presents a pressure drop which limits the flow of additional gas supplied to the breathing mask (dotted curve in FIG. 1), to a value closer to the physiological minimum necessary for a given altitude (curve in dashes in Figure 1).

Means are advantageously provided to guarantee the safety of the user without intervention on his part or avoiding false maneuvers.

This goal can be achieved in several ways. By way of example, a regulator is provided comprising safety means having the following characteristics:

- they prevent the switching of the additional gas supply to the passage with the smallest section when there is no supply of dilution air (for example during a manual switching to mode called "$ 100 ", corresponding to a supply of additional pure gas to the breathing mask), and CA 02393068 2002-07-05 4 - they prohibit the supply of additional pure gas to the mask by cutting off the air supply, when the additional gas is supplied via the passage with the smallest section.

Advantageously, the regulator according to the invention comprises the following characteristics taken individually or in combination:

- the control means can be actuated manually;

- It comprises an altimeter capsule to actuate the control means as a function of the altitude.

When the regulator is mounted on an inflatable harness breathing mask, it includes a harness inflation actuator to connect the additional gas supply with the inflatable harness to inflate it; advantageously, the control means cooperate with the harness inflation actuator to switch the supply of additional gas to the full flow passage, when the harness inflation actuator is activated to inflate the harness.

For example, the control means switch the supply of additional gas to the full flow passage, under the effect of the pressure of the gas supplying the harness.

CA 02393068 2002-07-05 ~. According to another aspect, the invention is an enriched respiratory gas generator comprising a pressure regulator according to the invention.

Other aspects, aims and advantages of the invention will become apparent on reading the following detailed description of several embodiments.

The invention will also be better understood with the aid of the appended drawings in which:

- Figure 1 shows, as a function of the altitude, the evolution of the additional gas enrichment corresponding to the physiological minimum necessary, the evolution of the additional gas enrichment supplied by additional gas generators and the flow rate in additional gas supplied by a flow regulator according to the invention;

- Figure 2 shows schematically in section the fluid circuit of one embodiment of a flow regulator according to the invention;

- Figure 3 shows partially and schematically in section the fluidic circuit of another embodiment of the flow regulator shown in Figure 2;

- Figure 4 shows partially and schematically in section the fluidic circuit of yet another embodiment 'CA 02393068 2002-07-05 = 6 of the flow regulators shown in Figures 2 and 3; and - Figure 5 shows schematically in section safety means intended to equip regulators according to the invention.

According to a first embodiment, illustrated by FIG. 2, the demand regulator 1 according to the invention is provided with a flow limiter 2 with control by inflation actuator of a breathing mask wearing harness.

The regulator 1 comprises a box and a "normal / $ 100" switch 3, shown in FIG. 2 in the "100V" position (air inlet closed).

The housing is made up of several assembled parts defining a fluid circuit.

It has several fluid communications with the outside of the housing: a nozzle 27 for supplying additional gas, a connecting tube 4 with the inside of a breathing mask (not shown), an air inlet 5 for dilution, a vent passage 6 and an exhaled gas outlet 7.

It also comprises an inlet 8 in communication with the flow restrictor 2_ The housing further comprises several internal fluid communications: a primary duct 9 - CA 02393068 2002-07-05 7 comprising a calibrated constriction 22 and a secondary duct 10 connecting the compartments separated by a main valve 11 to a compartment 21 corresponding to a pilot valve 12.

The box also includes several switching members to modify the flow of fluids in the circuit defined by the box.

These switching members are the main valve 11 and the pilot valve 12; the regulator shown further has a valve 13 for venting the compartment 21 of the pilot valve 12 and an altimeter capsule 14.

The constitution of the valves is classic.

In the illustrated case, the main valve 11 consists of a membrane 15 cooperating with a fixed seat 16.

The membrane 15 separates a control chamber 17 from the inlet 8, from the primary duct 9 and from the connecting pipe 4_ The control chamber 17 is connected to the inlet 8 by a calibrated constriction 18.

When it is subjected to the additional gas inlet pressure, the membrane 15 is applied against the seat 16, closes the passage of the additional gas in this seat 16 and separates the inlet 8 from the pipe 4.

The pilot valve 12 comprises a membrane 19 sensi.ble to the pressure.

The membrane 19 carries a shutter CA 02393068 2002-07-05 8 20 which cooperates with a fixed seat to put the control chamber 17 in communication with the compartment 21 delimited by the membrane 19 or on the contrary to separate the chamber 17 and the compartment 21.

The compartment 21 also communicates with the admission 8 through the constriction 22.

The pilot valve 12 also constitutes an exhaust valve allowing the exit of the exhaled gases by the exhaled gas outlet 7.

The pressure which prevails in the chamber 21 is limited by the vent valve 13 which prevents the overpressure in the chamber 21 from exceeding a predetermined value.

The altimeter capsule 14 cuts off or allows the entry of air through the inlet of dilution air 5 as a function of the altitude. At high altitude, the altimeter capsule 14 cuts off the inlet of dilution air, so that the mask is supplied only with additional gas coming from the flow limiter 2.

The operation of regulator 1 is known and is therefore not detailed here.

Reference may be made, for more details on its operation, to documents FR-A-1 557 809 and FR-A-2 781 381.

CA 02393068 2002-07-05 9 The flow limiter 2 comprises a full flow / economic actuator 23, a passage with restricted section 25, a passage full flow 26.

The regulator 1 shown further has a harness inflation actuator 41, a harness connector 28, a plunger 29 and a piston 30. The harness inflation actuator 41 has a valve 42 and an ear 24.

The full flow passage 26 has a section such that the additional gas is transmitted through this passage with a maximum flow rate making it possible to supply the user with pure additional gas in a physiologically sufficient manner at the maximum expected altitude.

The restricted section passage 25 corresponds to a so-called economic flow rate and reduces the additional gas flow rate transmitted from the supply 27 to the inlet 8.

The plunger 29 has a zone of reduced diameter.

Depending on the position of the plunger 29, this zone places the supply 27 in communication, both with the passage with restricted section 25 and with the full flow passage 26, or only puts the supply 27 in communication with the passage to restricted section 25.

The plunger can be moved between these two positions by manual action on the full actuator - CA 02393068 2002-07-05 flow / economic 23 or by a piston 30 belonging to the harness inflation valve 42.

The piston 30 can be temporarily brought into the position shown by the harness inflation lug 24.

In this rest position, the power supply 27 and the harness inflation connector 28 do not communicate.

In the other position, a groove 31 of the piston 30 places the power supply 27 and the harness connector 28 in communication.

When the piston 30 is brought into the haxnais inflation position, it moves the plunger 29 to its position where the supply 27 is in communication with the restricted section passage 25 and with the full flow passage 26, if the plunger 29 does not is not already in this position.

This is a safety measure.

Thus, with the embodiment of the invention described here, the user's first inspiration through the mask cannot be limited by an insufficient flow of additional gas. The user can then, if desired and if it is useful, switch to economic mode by bringing the plunger 29 to the so-called economic position where only the passage with restricted section 25 is in communication with the power supply 27.

However, also as a safety measure, to switch to this economic mode, CA 02393068 2002-07-05 the user must first position the normal / 100% 3 actuator in the normal position (position offset to the left with respect to that shown in figure 2) that is to say with admission of dilution air.

The passage to restricted section 25 does not in fact make it possible to supply the user with 100% additional gas at a sufficient flow rate.

Figure 1 shows a case where the user switches the actuator 23 to 2500 m to limit the flow of additional gas to 0.65 l / min (NTPD) below this altitude (see curve in poxntxllés).

Above this altitude, the user will remain or return to full flow of additional gas, by positioning the full flow / economy actuator 23 in its position allowing communication of the supply 27 with the full flow passage 26.

According to yet another variant, the flow limiter 2 comprises several passages with restricted section 25 of different sizes and which can be selectively placed in communication with the power supply 27, so as to approach the flow rate curve corresponding to the physiological minimum by stages. corresponding to limited flow rates.

- CA 02393068 2002-07-05 12 According to a second embodiment, illustrated by FIG. 3, the demand regulator 1 according to the invention is provided with a flow limiter 2 with control by altimetric capsule.

Regulator 1 is identical to that described previously.

The flow limiter 2, according to this embodiment, comprises an altimeter capsule 32 and a shutter 33, in addition to the full flow / economy actuator 23, the harness inflation ear 24, the passage with restricted section 25 , the full flow passage 26, the supply 27 with additional gas, the harness connector 28, the plunger 29 and the piston 30 already described.

However, in this flow limiter 2, the plunger 29 and the piston 30 are independent.

The piston 30 is moved by the harness inflation ear 24 to put the groove 31 in communication with the power supply 27 and the harness connector 28, but in this movement, the plunger 29 is not stressed, whatever his position.

The supply 27 is connected to the passages with restricted section 25 and full flow 26, by the intermediary of a direct duct 34.

The direct conduit 34 permanently puts CA 02393068 2002-07-05 13 the power supply 27 with the passage to restricted section 25.

A control duct 35 makes it possible to transmit the pressure of the additional gas in the supply 27, to the plunger 29.

At low altitude, the shutter 33 is pressed, by a spring or the elasticity of the capsule, on a seat and closes the control duct 35. At a predetermined a] .altitude, the altimeter capsule 32 sufficiently urges the shutter. 33 to overcome the action of the spring.

The control duct 35 opens and the plunger 29 is moved under the pressure of the respiratory gas to the full flow position, if it was in the economy position.

Thus, the user is assured of always having a sufficient supply of respiratory gas whatever the altitude.

According to a third embodiment, illustrated in pazla in FIG. 4, the demand regulator 1 according to the invention is provided with a flow limiter 2 sensitive to the pressure in the harness.

The regulator 1, in this embodiment is also identical to that described in relation to the first embodiment.

The flow limiter 2, according to this embodiment, comprises a safety duct 36, between the piston 30 and the plunger 29, in addition to the full actuator CA 02393068 2002-07-05 14 flow / economic 23, of the The harness inflation actuator 24, the restricted section passage 25, the full flow passage 26, the respiratory gas supply 27, the harness connector 28, the plunger 29 and the piston 30 already described.

However, as for the second embodiment, in this flow limiter 2, the plunger 29 and the piston 30 are independent.

The piston 30 is moved by the harness inflation ear 24 to put the groove 31 in communication with the power supply 27 and the harness connector 28.

In this movement, the plunger 29 is not requested, but the additional gas sent into the harness is also sent into the safety duct 36 and with the same pressure.

This pressure is sufficient to move the plunger 29 to the full flow position, if it was in the economy position.

The user's first inspiration through the mask cannot therefore be limited by an insufficient flow of additional gas_ Here again, the user can then, if he wishes and if he deems it useful, switch to economy mode by requesting the full flow / economic actuator 23 to move the plunger 29 into the so-called economic position where only the passage with restricted section 25 is in communication with the power supply 27, with the same safety measure, insured - CA 02393068 2002-07-05 by the normal actuator / $ 100 3, than that described in relation to the first embodiment.

Although the regulator 1 can be placed on a user's seat, it is generally on civilian aircraft 5 worn by the user's mask.

The mask is in the standby position or stored in a mailbox 37.

In this case, illustrated by FIG. 5, the regulator 1 is advantageously provided with safety means intended to bring the normal / 100% actuator 3 to the 100% position when the mask equipped with the regulator 1 is taken out of the reception box. 37.

These security means consist for example of an elastic lock 38 placed on the reception box 37 and intended to cooperate with a stud 39 of the normal actuator / 100b 3.

When the mask equipped with the regulator 1 is introduced into the receiving box 37, in the direction of arrow F, the latch 38 brings, to the right in FIG. 5, the normal actuator / 100% 3 so that that it must be in the 100% position once the mask has been taken out of its inbox 37.

This further prevents, as explained above, that the full flow / economy actuator 23 is in the economy position when the mask is taken out of its reception box 37.

CA 02393068 2002-07-05 16 Numerous variants of the invention can be designed without departing from the scope of the invention. This is the case in particular, when several characteristics described above are combined, such as those intended to ensure the safety of the user of the regulator and of the flow limiter according to the invention.