Oxygen supply and distribution system for a passenger aircraft

0001The invention, which is claimed in claims 1 and 19, relates to the supply and distribution of therapeutic oxygen to the passengers of an aircraft which is equipped with an emergency oxygen system that becomes operational in response to a drop of cabin pressure below a predetermined level.

BACKGROUND INFORMATION

0002Certain passengers must breathe additional oxygen at any time or at all times during a flight independently of the current operational status of the emergency oxygen supply system. This requirement for additional oxygen occurs particularly when the cabin pressure is lower than the normal atmospheric pressure at seal level, but not low enough to trigger the operation of the emergency oxygen supply. Such persons may require additional oxygen during the entire flight time and during times while sitting in the aircraft on the ground. For this purpose it is customary to use chemical oxygen generators, portable oxygen bottles or tanks, or portable oxygen generators known as OBOGS (on board oxygen generator system). These additional oxygen sources and their respective distribution systems are not permanently installed in an aircraft and require installation and maintenance when an aircraft is prepared for its next flight.

0003This disclosure distinguishes between an emergency oxygen supply and a therapeutic oxygen supply made available for passengers who require extra oxygen.

0004Certain types of aircraft have a permanently installed therapeutic oxygen supply system including a therapeutic oxygen source installed at a certain location within the aircraft. The distribution of therapeutic oxygen is performed through a separate conduit system connected to oxygen taps in the aircraft cabin. These oxygen taps are constructed for connecting therapeutic oxygen breathing masks to the taps for passengers who require such a therapeutic oxygen supply service.

0005It is also conventional to have small portable oxygen supply bottles on board for those passengers that only have a temporary breathing problem for which they require additional oxygen.

0006There are basically four conventional approaches for the supply of therapeutic oxygen to aircraft passengers. Chemical oxygen generators for supplying therapeutic oxygen to passengers require repeated installation, removal, and maintenance work including safety checks. Such chemical oxygen generators must be triggered either manually or automatically. Further, systems with chemical oxygen generators require the installation of more or fewer generators, depending on the flight duration and on the estimated number of passengers that may want to use therapeutic oxygen. Once chemical oxygen generators have been activated it is not possible to deactivate such generators, whereby the produced oxygen that is not used for the therapeutic services, is wasted. If a decompression of the cabin pressure occurs, in response to which the emergency oxygen system is activated, the user of the therapeutic oxygen supply system must exchange the therapeutic oxygen breathing mask against an emergency oxygen breathing mask. The passengers need to be instructed accordingly and in an emergency, confusion may result as to which mask is which.

0007<patcit id="pcit0001" dnum="US4651728A"><text>US 4,651,728</text></patcit>, which is considered being the closest prior art showing all the features of the preamble of claim 1 and 19 discloses a breathing system which is provided for supplying physiologically acceptable breathing gas to a pilot of an aircraft. The system includes a breathing mask connected to a pressure regulator. The pressure regulator is connected to a selector valve. Connected to the selector valve is an on-board oxygen generating system and a standby oxygen supply. The selector valve selects breathing gas from one of these two sources. Also included in the system is an emergency oxygen bottle connected to the regulator. Ambient air is supplied to the mask by an ambient air flow duct if for some reason none of the breathing . gas sources provide breathing gas to the regulator.

0008Similar considerations apply to the use of portable oxygen bottles for the supply of therapeutic oxygen. Such bottles have their own masks which must be exchanged against the emergency oxygen breathing mask when the cabin pressure drops below the predetermined level. Additionally, portable oxygen supply bottles need a control that is responsive to the current cabin pressure. Such control must be explained to the user which also may result in confusion. The foregoing considerations also apply to portable oxygen generators (OBOGS). Here again a switch between different oxygen breathing masks is required when the emergency oxygen system becomes effective.

0009Similar considerations apply to a permanently installed therapeutic oxygen supply system which also has its own separate oxygen masks that must be exchanged for emergency oxygen masks when the emergency oxygen supply system becomes effective in response to a failed cabin pressure.

OBJECTS OF THE INVENTION

0010In view of the foregoing it is the aim of the invention to achieve the following objects singly or in combination: <ul id="ul0001" list-style="none"><li>to construct an oxygen supply system for a passenger aircraft in such a way, that the same oxygen breathing masks can be used for a continuously available therapeutic oxygen supply or for an emergency oxygen supply;</li><li>to use at least a portion of the emergency oxygen distribution conduit system also for the distribution of therapeutic oxygen;</li><li>to minimize the effort and expense for the installation and maintenance of the entire oxygen supply and distribution system and particularly the therapeutic oxygen supply and distribution system of a passenger aircraft; and</li><li>to make the use of the emergency oxygen supply and the use of the therapeutic oxygen supply as simple as possible for the passengers to avoid confusions.</li></ul>

0011The invention further aims at avoiding or overcoming the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification. The attainment of these objects is, however, not a required limitation of the present invention.

SUMMARY OF THE INVENTION

0012The above objects have been achieved according to the invention by the combination of the features of the independent claim 1 or 19, respectively.

0013The main advantage of the invention is seen in that duplications of oxygen supply components such as masks, conduits in the form of pipes and/or hoses, as well as valves are substantially reduced. Another advantage of the invention is seen in that a supply of therapeutic oxygen is available to any therapeutic passenger at all times when that passenger is onboard and that an emergency oxygen supply is available to all passengers when the cabin pressure falls below a predetermined level, whereby the therapeutic passengers can use the same masks in both instances. Still another advantage of the present system is seen in that a sufficient oxygen supply for therapeutic purposes and for emergency purposes is available on board of the passenger aircraft at all times, yet the weight and costs are reduced because certain components such as conduits, valves and particularly the oxygen breathing masks are used for both emergency and therapeutic purposes.

BRIEF DESCRIPTION OF THE DRAWINGS

0014In order that the invention may be clearly understood, it will now be described in connection with example embodiments thereof, with reference to the accompanying drawings, wherein: <dl id="dl0001"><dt>Fig. 1</dt><dd>shows a first embodiment with bottles or tanks forming an emergency oxygen supply while an additional bottle of the same construction forms a therapeutic oxygen supply with both supplies connectable to the same oxygen masks;</dd><dt>Fig. 2</dt><dd>shows a second embodiment in which the therapeutic oxygen supply is an onboard oxygen generator with both supplies connectable to the same masks as in <figref idref="f0001">Fig. 1</figref>;</dd><dt>Fig. 3</dt><dd>shows the same oxygen supply system as in <figref idref="f0002">Fig. 2</figref>, with a modified oxygen distribution wherein the oxygen masks are connected to an emergency oxygen conduit which in turn is connected through a valve to a therapeutic oxygen conduit;</dd><dt>Fig. 4</dt><dd>shows a further embodiment in which the therapeutic oxygen supply system comprises an onboard battery of oxygen generators with the oxygen distribution as in <figref idref="f0001">Figs. 1</figref> and <figref idref="f0002">2</figref>, and wherein the battery of oxygen generators may be used to supplement the oxygen supply for the emergency system; and</dd><dt>Fig. 5</dt><dd>illustrates an embodiment in which the oxygen supply is the same as in <figref idref="f0004">Fig. 4</figref> with an oxygen distribution as in <figref idref="f0003">Fig. 3</figref>.</dd></dl>

DETAILED DESCRIPTION

0015Features that are the same in more than one Fig. will be described first and only once. <figref idref="f0001">Figs. 1</figref>, <figref idref="f0002">2</figref> and <figref idref="f0004">4</figref> show an emergency oxygen supply subsystem EOS and a therapeutic oxygen supply subsystem TOS. The emergency subsystem EOS comprises three oxygen bottles 1 connected to a common filling port 2 by a filling conduit or pipeline 3. The emergency oxygen subsystem EOS comprises control means such as valves, pressure reducers and heat exchangers. The subsystem is connected in common through an emergency oxygen conduit EOC to at least one, preferably several oxygen distribution banks ODB to be described in more detail below.

0016All oxygen bottles or tanks 1 are of the same construction and are connected in common to a discharge port 4 by a conduit or pipe line 5. All oxygen distribution banks ODB are of identical construction and serve for an oxygen distribution from both supply subsystems EOS and TOS. Each oxygen distribution bank ODB comprises a conduit such as a pipeline, hose or the like 7 provided with a plurality of oxygen outlets 8 to which oxygen masks OM are connectable, for example by quick coupling plug-in connectors or the like. According to the invention the same therapeutical oxygen masks OM also of identical construction are used in an emergency situation when the cabin pressure falls below a determined level or when a passenger requires a therapeutic oxygen supply. For this dual purpose each oxygen distribution bank ODB in <figref idref="f0001">Figs. 1</figref>, <figref idref="f0002">2</figref> and <figref idref="f0004">4</figref> is connected at one end through a respective check valve 9 to an emergency oxygen supply conduit EOC leading to the emergency supply EOS. The other end of each oxygen distribution bank ODB is connected through a respective further check valve 10 to a therapeutic oxygen supply conduit TOC leading to the therapeutic oxygen supply subsystem TOS.

0017The oxygen distribution banks ODB in <figref idref="f0003">Figs. 3</figref> and <figref idref="f0005">5</figref> are of identical construction with a conduit 7 and oxygen outlets 8. The check valves 9 and 10 are omitted in <figref idref="f0003">Figs. 3</figref> and <figref idref="f0005">5</figref>. Instead, all oxygen distribution banks ODB are directly connected in common to the emergency oxygen supply conduit EOC. The conduit EOC is connected to the supply EOS as in <figref idref="f0001">Figs. 1</figref>, <figref idref="f0002">2</figref> and <figref idref="f0004">4</figref> and additionally through a single check valve 11 to the therapeutic oxygen supply conduit TOC leading to the therapeutic oxygen supply subsystem TOS.

0018The therapeutic oxygen supply subsystem TOS in <figref idref="f0001">Fig. 1</figref> comprises an additional oxygen bottle 1' (or more) of the same construction as the bottles 1' of the emergency oxygen supply subsystem EOS. The additional bottle 1' is also connected to the discharge line 5 through an extension discharge line 5' connected to the line 5. Similarly, the therapeutic oxygen supply bottle 1' is connected through a pipeline extension 3' of the pipeline 3 to the filling port 2. Thus, all four (or more) oxygen supply bottles 1 and 1' can be filled simultaneously when the aircraft is in maintenance. The filling line extension 3' is connected to the supply bottle 1' through a heat compensator or heat exchanger 12 for keeping the temperature of the supply systems TOS and EOS at an acceptable limit during rapid filling of the bottles 1 and 1'. The therapeutic oxygen supply conduit TOC is connected through a controllable shut-off valve 13 and through a pressure controller, particularly a pressure reducer 14 to the therapeutic oxygen supply bottle 1'. A control connection 15 such as an electrical conductor, a pneumatic or hydraulic line or the like connects the controllable shut-off valve 13 to a control member such as a switch 16. The valve 13 can thus be opened or closed by a crew member as needed by an electrical, a pneumatic, or a mechanical, or any other suitable control. A pressure conduit 17 connects the pressure reducer 14 to a pressure indicator 18. The pressure indicator 18 tells the crew the pressure in the therapeutic oxygen supply bottles 1', thereby enabling the crew to determine the quantity of oxygen still remaining in the supply bottles 1'.

0019A safety valve 19 interconnects the discharge pipeline extension 5' with the therapeutic oxygen conduit TOC to relieve any excess pressure in the therapeutic oxygen supply subsystem TOS through the conduit 5 and out the discharge port 4.

0020In operation, the therapeutic oxygen supply subsystem TOS will be switched on by opening the valve 13 so that any passenger can receive therapeutic oxygen through any of the masks OM. In an emergency, when the cabin pressure falls below a predetermined mandatory level, the valve 10 will be closed and the valve 9 will be opened either automatically in response to the pressure drop and the emergency oxygen supply subsystem EOS will be switched on. Thus, a passenger or any passenger can receive oxygen either from the therapeutic oxygen supply TOS at all times onboard when the cabin pressure is normal or from the emergency oxygen supply EOS when the cabin pressure is below normal but always through the same mask OM. The important advantage of the embodiment of <figref idref="f0001">Fig. 1</figref> is seen in that all oxygen supply bottles 1 and 1' can be filled simultaneously and that the oxygen distribution banks ODB and the masks OM can be used by both supply systems EOS and TOS by an appropriate control of the valves 9, 10 and 13.

0021Each of the five embodiments shown in <figref idref="f0001 f0002 f0003 f0004 f0005">Figs. 1 to 5</figref> comprises a test port closeable by a shut-off valve 20 for checking whether the therapeutic oxygen supply subsystem TOS and its conduit TOC are properly sealed so that there are no leaks. Further parts 21 perform the same function in each of the five embodiments for the emergency oxygen supply EOS and its conduit EOC.

0022In <figref idref="f0002">Figs. 2</figref> and <figref idref="f0003">3</figref> the therapeutic oxygen supply subsystem TOS is the same in the form of an oxygen generator 22 connected to the oxygen distribution banks ODB through the therapeutic oxygen conduit TOC. The generator 22 is connected to a gas venting conduit 23 for bleeding nitrogen N₂ from the top of the oxygen generator 22 which is also connected to a bleed air pipeline 24 at its bottom. A control line 25 connects the oxygen generator 22 to a control panel with a switch 26 that may be operated as described above with any suitable command transmission through the control line 25.

0023In <figref idref="f0004">Figs. 4</figref> and <figref idref="f0005">5</figref> the oxygen generator 22 is reinforced by additional oxygen generators 22' connected in parallel with the portable oxygen generator 22 to form a battery of such oxygen generators. The battery of oxygen generators is connected in common at the top of the generators to the gas vent line 23 while the bottom of the battery is connected to the bleed line 24 just as in the <figref idref="f0002">Figs. 2</figref> and <figref idref="f0003">3</figref> with the single oxygen generator.

0024In <figref idref="f0004">Figs. 4</figref> and <figref idref="f0005">5</figref> a shut-off valve 27 and a conduit 27' connected to the conduit EOC permit using oxygen generated by the generator battery 22, 22' in the emergency oxygen supply system, if needed. Again, the same oxygen distribution banks ODB and the same therapeutic oxygen breathing masks OM will be used.

0025Incidentally, the determination of a sufficient oxygen supply for emergency and therapeutic purposes will depend on the type of passenger aircraft, on the flight duration, and on a safety margin that is determined on past experience.

0026Although the invention has been described with reference to specific example embodiments, it will be appreciated that it is intended to cover all modifications and equivalents within the scope of the appended claims. It should also be understood that the present disclosure includes all possible combinations of any individual features recited in any of the appended claims.