WO1989002293A1 - Breathing apparatus - Google Patents

Abstract

Breathing apparatus, particularly for use in passenger aircraft, provides a battery-powered centrifuge mounted under the passenger seat and delivering downstream through a catalytic filter to an ori-nasal mask and hood assembly having similar filter means. The delivery tube from the centrifuge is a friction fit in the mask and readily disconnected for mobile use of same. Disconnection automatically seals the opening and the user then can draw external air through the filter and/or clean air or oxygen from the reservoir thereof constituted by the hood during mobile use. One-way valves control inhalation and exhalation. The hood is extensible and collapsible to provide a visual indication of the extent of the oxygen reservoir remaining.

Description

  
 



   BREATHING APPARATUS
 This invention relates to breathing apparatus. An example of the application of the invention is to breathing apparatus for use in passenger aircraft. However, the invention may well be considerably more widely applicable.



   There is a considerable requirement for breathing apparatus, suitable for use in aircraft in the event of fire. Existing aircraft provide an   or i-nasal    mask delivering a mixture of cabin air and extra oxygen, in the event of decompression during flight. Such equipment is unsuitable for use in aircraft fires, not least on account of the fact that the cabin air delivered may well be badly contaminated. A further factor is that, of course, these   or i-nasal    masks are fed by ducts or tubes and thus offer no mobility for the passenger when the time comes to escape from the aircraft.



   Previously proposed breathing apparatus for other situations include a simple system for taking air from floor level for breathing purposes, and gas/filter systems.



   Shortcomings of these prior proposals include the fact that air at floor level may not be breathable, and may contain poisons together with significant amounts of particulate matter. Moreover, these contaminants are inclined to enter the clean air system at joints and seals.



  So far as filter systems are concerned, these have a limited useful life under the adverse conditions in aircraft fires, particularly due to large particles of dispersed solid matter in the air. Moreover, these systems tend to be heavy and expensive and thus are not suitable for provision for each aircraft passenger. A further requirement is for protection for the user's eyes.



   An object of the present invention is to provide breathing apparatus offering improvements in relation to one or more of the matters discussed above, or generally.



  Amongst the requirements met by the embodiments described  below are the provision of a supply of air on a temporary basis and of a breathable quality, together with provision for mobility of the user, and the apparatus not being heavy or expensive
 According to the invention there is provided breathing apparatus as defined in the accompanying claims.



   In a preferred embodiment of the invention, breathing apparatus, particularly for use in passenger aircraft, provides a battery-powered centrifuge mounted under the passenger seat and delivering downstream through a catalytic filter to an ori-nasal mask and hood assembly having its own filter means. The delivery tube from the centrifuge is a friction fit in the mask and readily disconnected for mobile use of same. Disconnection automatically seals the opening and the user then can draw external air through the filter and/or clean air or oxygen from the reservoir thereof constituted by the hood during mobile use. One-way valves control inhalation and exhalation. The hood is extensible and collapsible to provide a visual indication of the extent of the air reservoir remaining.



   In the preferred embodiment, the driven centrifuge provides for removal of entrained matter in the air supply, thereby delivering through the filter a breathable supply of air whereby it is not necessary for the mask filter to be employed until this supply of air is disconnected for mobile use. Hence, the mask filter is protected and the advantages of static and mobile systems are combined.



  Moreover, a mobile and lightweight and inexpensive clean air or oxygen reservoir is provided, in the form of the hood, which also serves as an indicator of the state of this reservoir.



   In the embodiment described below, the apparatus is suitable for use in atmospheres containing adequate, ie about 17 per cent minimum of oxygen, but made potentially incapacitating by the presence of one or more noxious  substances such as particulate and gaseous products of combustion, or chemical escapes.



   Protection of the user's nose, mouth and eyes is provided either by an ori-nasal mask or/and an allenveloping hood. The hood may, if desired, be provided with a shoulder apron to which a battery/motor/filter pack and/or a breathable gas container is permanently attached.



  The mask or hood may have three optional features, namely firstly an outward relief valve which, when pressurised, prevents excess pressure build-up, and secondly a filter panel to filter incoming air, thu-s affording time before concentrations of carbon monoxide and/or carbon dioxide can rise to dangerous levels should the pressurising air flow fail for any reason, or be disconnected for mobile use.



  Thirdly, a container of breathable gas and/or catalyst may be provided which is released when the hood or mask is disconnected from an external pressurising air supply.



  Filters, (particulate, catalytic and absorption/adsorption as necessary for the specific atmosphere concerned), together with the pressurising fan/centrifuge, its driving motor and the associated battery power supply are housed together in a common package connected by a suitable hose or other means to the mask or hood.



   The centrifuge and air purifying/filter means, together with its battery and motor, may be provided for fixed or portable installation. The latter may be mounted by means of a waist strap, shoulder sling or hand carrying means, or in miniaturised form may be mounted on the shoulder, apron or hood assembly.



   The fixed installation of the centrifuge and filter assembly is preferably located under the seat mounting for passengers. Evidence from aircraft accidents indicates that relatively clean air or oxygen is available at this location. The breathable air is delivered to the hood, inflates same, and after disconnection this reservoir provides sufficient clean breathable gas for several  minutes survival. The risk of subsequent suffocation is lessened, if not eliminated, by the provision of either a breathable gas cylinder or hood inlet filter which is brought into use when the hose and hood or mask are separated from one another. Such separation is by means of a self-sealing or filtering connection.



   In the fixed installation, stowage provision is provided for the hood or mask, with the latter already coupled to the centrifuge assembly for immediate use. This complete unit is sealed to conserve filter life until it is opened for withdrawal of the hood or mask and connecting hose. The action of opening the unit initiates operation of the pressurising fan/centrifuge motor.



   Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:
 Fig 1 shows, somewhat diagrammatically, a hood and air inlet means therefor;
 Fig 2 shows, again somewhat diagrammatically, and on a larger scale, the arrangement for connecting a clean air delivery tube to an   or i-nasal    mask through a valve and filter assembly;
 Fig 3 shows, in a similar view, the apparatus of Fig 2 with the air supply tube removed and a hood indicated together with a one-way air inlet valve from the hood, and a separate oxygen supply;
 Fig 4 shows a centrifuge and filter assembly for delivering clean air to the apparatus of Figs 1 to 3; and
 Fig 5 shows a modified form of the apparatus of Fig 4.

 

   As shown in Figs 1 to 3, breathing apparatus 10, to supply breathable air in a contaminated atmosphere, comprises a hood 12 to surround and enclose the human face and head, sealing means 14 for the hood to co-operate with the human body or with clothing thereon to resist entry of contaminated air, and inlet means 16 to admit a supply of breathable air or oxygen.  



   Hood 12 is in the form of an envelope of flexible sheet material to contain a reservoir of breathable air delivered through inlet 16. The hood may be made entirely from transparent material wh-ich may be wholly or partially coated with a reflective material. Alternatively, the hood material may be a woven and/or coated fabric having a transparent portion for visibility purposes.

  In either case, the physical characteristics of the hood are such that it can be initially inflated by the air delivered through inlet 16 or by oxygen so as to adopt an enlarged or extended configuration, the hood likewise being collapsible as the supply or reservoir   therein    is consumed or discharged, whereby during use of the apparatus 10, the relative size of the hood and/or its configuration after a period of use provides a visible indication to the user and/or others as to the extent of the remaining reservoir of breathable air or oxygen therein.



   The sealing means 14 may comprise an elasticated collar or garter portion to permit insertion of the head and subsequent sealing around the user's neck.



  Alternatively, a shoulder apron may be provided or the like, possibly with velcro or the like for adhesion purposes. These details are not shown in Fig 1. Likewise, an inlet duct 18 for breathable air together with an oxygen duct 20 and a filter 22 are indicated in simple fashion in
Fig 1 and are more fully described below.



   In the simple embodiment of Fig 1, the sealing means 14 provides a means for outward discharge of exhaled air and the ori-nasal mask of Figs 2 and 3 is not provided.



   Turning now to Fig 2, it will be noted that the inlet duct 18 extends through a seal 24 in an air inlet housing 26 having an ori-nasal mask 28 (constituting air delivery means) at its open inner end, for sealing engagement with the user's face, such engagement being maintained by a draw cord 30 extending around the user's neck and tied at 32 around duct 18, and thus frictionally gripping the duct.  



  Hood 12 is not shown in Fig 2 since in this embodiment without a separate supply of oxygen the hood need not be employed, its function being more important for mobile use, as an oxygen reservoir, as discussed below.



   At the delivery end of duct 18, a series of circumferentially spaced openings 34 are formed in the duct to allow air to freely pass into housing 26, as indicated by arrows 36. In this configuration, the inner end of duct 18 holds a valve 38 open. Valve 38 comprises a housing 40, valve springs 42, 44 and a valve member 46.



   In use, air is delivered through duct 18 and openings 34 via apertures 48 in housing 40 to   or i-nasal    mask 28 and thus to the user. As the user exhales, the exhaled air is delivered outwards and around the mask since the draw cord 30 is not tight. If a hood 12 is in place, the exhaled air can escape around the seal 14.



   Fig 3 shows a modification incorporating an oxygen supply duct 20 and an inlet valve 50. Fig 3 also -shows the configuration of valve 38 when duct 18 is withdrawn for mobile use.



   With regard to the oxygen duct 20, this optional feature permits the apparatus to meet the requirements of aircraft passengers in the event of cabin pressurisation failure. The oxygen is delivered to hood 12 directly. The user tightens draw cord 30. Duct 18 has been removed.



  This is achieved simply by pulling on it. The friction fit in seals 24 permits the duct to be removed without difficulty. As a result, springs 42, 44 close valve 38, which now functions as a one-way exhalation valve. Inlet valve 50 permits oxygen to be drawn by the user from the reservoir thereof in hood 12, in a one-way fashion. The user then obtains a mixture of oxygen and filtered/purified cabin air, the one via valve 50 and the other via catalytic filter 22, the proportion depending upon the relative magnitudes of the loading exerted by valve spring 52 and the resistance provided by catalytic filter 22.  



   It will be understood that upon disconnection of the oxygen supply conduit 20, the hood 12 will be extended and inflated. As the user consumes a balanced mixture of oxygen from the hood and filtered/purified air obtained via catalytic filter 22, and the user exhales via the one-way outlet valve 38, the volume of oxygen in hood 12 will reduce and the hood will begin to retract and collapse, thus providing a visible indication of the remaining extent of the oxygen reservoir. The same applies in the case of mobile use of the apparatus 10 after inflation of the hood by the clean air supply from duct 18 and/or oxygen 20.



  Total collapse of the hood only indicates exhaustion of air and/or oxygen initially retained within the hood, and inlet filter 22 will continue to function with minimal retention of expired carbon dioxide within the   or i-nasal    mask, thus permitting continued normal breathing by the user.



   Turning now to the clean air supply means shown in Fig 4, this is intended to be mounted at a suitable fixed location, such as under each passenger seat, with its outlet delivery duct 18 connected to the apparatus of Figs 1 to 3, as described above.



   Clean air supply apparatus 54 comprises a cylindrical housing 56, a motor 58 driving a fan or centrifuge 60 which draws air from the ambient atmosphere via an inlet bellmouth 62.



  Downstream of fan 60 is a catalytic filter 64 having its downstream side connected by a funnel 66 to duct 18, which of course is flexible. An annular outlet or discharge 68 is provided between the filter and funnel assembly and housing 56, the former being mounted on the latter by means of narrow radial, supports not shown.



   Motor 58 is powered by a battery pack, not shown, arranged to be energised on the user gaining access to or removing the head end apparatus of Figs 1 to 3 and/or donning same.



   When- motor 58 is energised, fan/centrifuge 60 draws  air through inlet 62 in the direction indicated by arrow I and the air is discharged through duct 18 in the direction indicated by arrow 0, as described below. Cylindrical housing 56 acts as a swirl chamber whereby particulate matter collects on the surface of the chamber and is discharged through outlet 68, leaving relatively clean air to enter the catalytic filter 64, which is thus protected from blockage by such particulate matter, and a relatively clean and pure supply of breathable air is delivered to duct 18.



   The embodiment of Fig 5 is less preferred and uses similar reference numerals to Fig 4, but in this case the filter 64 is upstream of the fan 60 and thus is not protected from blockage by particulate matter.



   The above embodiments provide the means for survival and escape from atmospheres made hazardous by products of combustion and other sources. They combine a protective hood and ori-nasal mask or other means for enclosing the nose, mouth and eyes of the wearer, and means for supplying cleaned pressurising air or breathable gas. The endurance of this supply is determined by one or more of the following factors, namely the battery supply to the centrifuge, the resistance of the catalytic filter to blockage (mainly a significant factor only in mobile use) and in some cases the capacity of the supply of breathable gas or oxygen. The battery, fan and motor, and filter elements together with an optional breathable gas container are combined together in a pack which may be combined with the hood and mask or installed separately and linked by the delivery hose. 

  The mask and/or hood assembly may be detached from the pack for mobile use, with or without a supplementary cylinder of breathable gas or oxygen, or a miniaturised pack for delivering breathable air.



   The fan of the clean air delivery system may be arranged to push or pull air through the catalytic filter element. The push arrangement is preferred on account of  increased air pressure and reduced air velocity, thereby reducing back pressure. Also, the rotational motion of air and particulate matter in the airstream causes centrifugal separation. In this way, particulate matter is removed before reaching the filter, thereby prolonging its life.



  The air discharged with the particles may be directed to cool the outlet from the catalytic filter, thereby reducing the effect of any exothermic reaction therein.



   The hood acts as an economiser or buffer so that breathable air delivery rate does not need to meet peak inspirational demands. The use of a continuous as opposed to a demand flow to the hood or mask at all times reduces the build-up of disabling exhaled gases. Moreover, the continuous ventilation of the hood increases comfort and reduces temperature rise due to body heat from exhaled gases. The airflow has little effect on hearing at low velocity and thus does not impede communication. The positive pressure of breathable air supplied eliminates breathing resistance.

 

   In the embodiment the air supply system has its own catalytic filter, itself protected by the centrifuge, and upon disconnection of same when a passenger opts for mobile use   ofthe    mask or hood assembly, a new and clean filter is brought into use. The centrifuge arrangement is unusual in that the separated matter is discarded and it is the remaining and relatively clean air which is used. 

Claims

1 Breathing apparatus for supplying breathable air in a contaminated atmosphere, the apparatus comprising: hood means to surround and enclose, at least partially, the human face and head; sealing means for said hood to co-operate with the human head, neck or body, or with clothing thereon, to resist entry of the contaminated atmosphere;

and inlet means to admit a supply of breathable air or oxygen to said hood; characterised by said hood means comprising an envelope of flexible sheet material to contain a reservoir of breathable air or oxygen and said envelope being of such physical characteristics that the hood is initially inflatable by a supply of breathable air or oxygen so as to adopt an enlarged or extended configuration, and said hood means likewise being collapsible as the supply or reservoir of air therein is consumed or discharged, whereby during use of the breathing apparatus the relative size of the hood and/or its configuration after a period of use provides a visible indication as to the extent of the remaining reservoir of remaining breathable air or oxygen therein.

2 Apparatus according to claim 1 characterised in that said envelope comprises at least a transparent portion for location in front of the user's eyes.

3 Apparatus according to claim 2 characterised in that said envelope is all or largely transparent.

4 Apparatus according to any one of claims 1 to 3 characterised by an or i-nasal mask having one-way inlet valve means to control the entry of breathable air or oxygen from said hood and one-way outlet valve means to control the discharge of exhaled air.

5 Apparatus according to any preceding claim characterised in that a valve in said inlet means is arranged to automatically close upon disconnection therefrom of an air supply duct or conduit, so as to prevent direct entry of contaminated air.

6 Apparatus according to claim 5 characterised by filter means to filter air admitted to said mask and arranged to be automatically brought into use upon said disconnection of said air supply duct or conduit.

7 Apparatus according to claim 6 when dependent on claims 5 and 4 characterised by the air flow resistance of said filter means being related to the vacuum required to open said inlet valve means, whereby a user breathes air from both sources.

8 Breathing apparatus to supply breathable air in a contaminated atmosphere comprising: delivery means for breathable air to deliver such air to the nose and/or mouth of a user; an air duct or tube connectible to the delivery means to deliver breathable air thereto; characterised by said duct or tube being removably received in an opening in said delivery means; and change-over means actuatable by disconnection of said tube or duct from said opening to prevent direct ingress of contaminated air through said opening and thus to permit the user to draw breathable air from an alternative supply.

9 Apparatus according to claim 8 characterised by said duct being a friction fit in said opening and being removable therefrom by the application of tension to the duct.

10 Apparatus according to claim 8 or claim 9 characterised by said- change-over means comprising a valve which is held open by said tube or duct until the latter is removed.

11 Apparatus according to any one of claims 8 to 10 characterised by said alternative supply of breathable air comprising an extensible hood to contain a reservoir of breathable air.

12 Apparatus according to claim 11 characterised in that said hood is connected to the delivery means through a oneway valve permitting flow from said hood to the delivery means.

13 Apparatus according to any one of claims 8 to 12 characterised in that said alternative air supply means comprises filter means to filter contaminated from the atmosphere.

14 Breathing apparatus to supply breathable air in a contaminated atmosphere, the apparatus comprising: delivery means for breathable air to deliver air to the nose and/or mouth of a user; and air treatment means connected between the external atmosphere and said delivery means to reduce contamination of air delivered to the user; characterised in that said air treatment means comprises a centrifuge.

15 Apparatus according to claim 14 characterised in that said centrifuge comprises a driven impellor to effect a centrifugal action.

16 The apparatus of claim 15 characterised by said impellor being located upstream of said delivery means, thereby to raise the air pressure on said upstream side.

17 Apparatus according to any one of claims 14 to 16 characterised by said apparatus being adapted to be mounted in a fixed position, for example under a passenger seat in an aircraft, and further characterised by disconnectible hose means to deliver air from said air treatment means to said delivery means.

18 Breathing apparatus according to any one of claims 14 to 17 characterised by filter/air purifying means located adjacent but downstream of said centrifuge.

19 An aircraft characterised by apparatus according to claim- 17 mounted under or adjacent each of a plurality of passenger seats.