Oxygen supply and distribution system for a passenger aircraft

Aircraft passengers who require a therapeutic oxygen supply independently of the prevailing cabin pressure, as distinguished from an emergency oxygen supply that depends on an inadequate cabin pressure, can breath therapeutic oxygen and/or emergency oxygen depending on the situation, through the same therapeutic oxygen masks. For this purpose a control accessible to the crew is used to connect a therapeutic oxygen supply to the emergency oxygen distribution system of the aircraft, whereby the source of oxygen is used either partially for therapeutic purposes or fully for emergency purposes.

PRIORITY CLAIM

This application is based on and claims the priority under 35 U.S.C. §119 of German Patent Application 103 40 985.8, filed on Sep. 5, 2003, the entire disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention 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

Certain 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 sea 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.

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

Certain 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.

It 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.

There 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.

Similar 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.

Similar 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

In view of the foregoing it is the aim of the invention to achieve the following objects singly or in combination: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;to use at least a portion of the emergency oxygen distribution conduit system also for the distribution of therapeutic oxygen;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; andto 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.

The 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

The above objects have been achieved according to the invention by the combination of the following features in an oxygen supply system for a passenger aircraft, which system comprises oxygen breathing masks (OM) accessible to passengers for use at any time for therapeutic purposes or for emergency purposes. The oxygen supply source thus has a capacity sufficient for both purposes and can be activated partially for therapeutic purposes and fully for emergency purposes. The oxygen source includes an emergency oxygen supply subsystem (EOS) with a first oxygen source (1) and a therapeutic oxygen supply subsystem (TOS) with a second oxygen source (1′,22), a first oxygen conduit (EOC) connecting said first oxygen source (1) to said oxygen breathing masks (OM), a second oxygen conduit (TOC) connecting said second oxygen source (1′,22) to said oxygen breathing masks (OM), controllable valve means in at least one of said first and second oxygen conduits (EOC, TOC) for selectively connecting said oxygen breathing masks to one of said first subsystem (EOS) or to said second subsystem (TOS), and a control (16,26) connected to said subsystems (EOS and TOS) for activating either the first or the second or both subsystems, whereby the same oxygen breathing masks (OM) are selectively usable for therapeutic or for emergency purposes.

The 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 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 passengers receiving therapeutic oxygen 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.

DETAILED DESCRIPTION OF A PREFERRED EXAMPLE EMBODIMENT AND OF THE BEST MODE OF THE INVENTION

Features that are the same in more than one FIG. will be described first and only once.FIGS. 1,2and4show an emergency oxygen supply subsystem EOS and a therapeutic oxygen supply subsystem TOS. The emergency subsystem EOS comprises three oxygen bottles1connected to a common filling port2by a filling conduit or pipeline3. 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.

All oxygen bottles or tanks1are of the same construction and are connected in common to a discharge port4by a conduit or pipe line5. 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 like7provided with a plurality of oxygen outlets8to which oxygen masks OM are connectable, for example by quick coupling plug-in connectors or the like. According to the invention the same therapeutic 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 inFIGS. 1,2and4is connected at one end through a respective check valve9to 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 valve10to a therapeutic oxygen supply conduit TOC leading to the therapeutic oxygen supply subsystem TOS.

The oxygen distribution banks ODB inFIGS. 3 and 5are of identical construction with a conduit7and oxygen outlets8. The check valves9and10are omitted inFIGS. 3 and 5. 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 inFIGS. 1,2and4and additionally through a single check valve11to the therapeutic oxygen supply conduit TOC leading to the therapeutic oxygen supply subsystem TOS.

The therapeutic oxygen supply subsystem TOS inFIG. 1comprises one or more additional oxygen bottles1′ of the same construction as the bottles1′ of the emergency oxygen supply subsystem EOS. The additional bottle1′ is also connected to the discharge line5through an extension discharge line5′ connected to the line5. Similarly, the therapeutic oxygen supply bottle1′ is connected through a pipeline extension3′ of the pipeline3to the filling port2. Thus, all four oxygen supply bottles1and1′ can be filled simultaneously when the aircraft is in maintenance. The filling line extension3′ is connected to the supply bottle1′ through a heat compensator or heat exchanger12for keeping the temperature of the supply systems TOS and EOS at an acceptable limit during rapid filling of the bottles1and1′. The therapeutic oxygen supply conduit TOC is connected through a controllable shut-off valve13and through a pressure controller, particularly a pressure reducer14to the therapeutic oxygen supply bottle1′. A control connection15such as an electrical conductor, a pneumatic or hydraulic line or the like connects the controllable shut-off valve13to a control member such as a switch16. The valve13can 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 conduit17connects the pressure reducer14to a pressure indicator18. The pressure indicator18tells the crew the pressure in the therapeutic oxygen supply bottle1′, thereby enabling the crew to determine the quantity of oxygen still remaining in the supply bottle1′.

A safety valve19interconnects the discharge pipeline extension5′ with the therapeutic oxygen conduit TOC to relieve any excess pressure in the therapeutic oxygen supply subsystem TOS through the conduit5and out the discharge port4.

In operation, the therapeutic oxygen supply subsystem TOS will be switched on by opening the valve13so 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 valve10will be closed and the valve9will be opened 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 ofFIG. 1is seen in that all oxygen supply bottles1and1′ 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 valves9,10and13.

Each of the five embodiments shown inFIGS. 1 to 5comprises a test port closeable by a shut-off valve20for checking whether the therapeutic oxygen supply subsystem TOS and its conduit TOC are properly sealed so that there are no leaks. Further components21perform the same function in each of the five embodiments for the emergency oxygen supply EOS and its conduit EOC.

InFIGS. 2 and 3the therapeutic oxygen supply subsystem TOS is the same in the form of an oxygen generator22connected to the oxygen distribution banks ODB through the therapeutic oxygen conduit TOC. The oxygen generator22is connected to a gas venting conduit23for bleeding nitrogen N2from the top of the oxygen generator22which is also connected to a bleed air pipeline24at its bottom. A control line25connects the oxygen generator22to a control panel with a switch26that may be operated as described above with any suitable command transmission through the control line25.

InFIGS. 4 and 5the oxygen generator22is reinforced by additional oxygen generators22′ connected in parallel with the oxygen generator22to 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 line23while the bottom of the battery is connected to the bleed line24just as in theFIGS. 2 and 3with the single oxygen generator.

InFIGS. 4 and 5a shut-off valve27and a conduit27′ connected to the conduit EOC permit using oxygen generated by the generator battery22,22′ in the emergency oxygen supply system, if needed. Again, the same therapeutic oxygen distribution banks ODB and the same oxygen breathing masks OM will be used.

Incidentally, 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.