Abstract:
A supplemental oxygen system and method is set forth for providing oxygen to an occupant of a pressurized aircraft. A flexible hood may be adapted to be stowed in a small volume when the flexible hood is deflated and may be further adapted to cover at least a portion of the head of the occupant and to provide a flow of oxygen to the occupant when the flexible hood is inflated. A source of oxygen may be adapted to rapidly inflate and deploy the flexible hood.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The invention is generally directed to supplemental oxygen systems, and more particularly, to supplemental oxygen systems for aircraft.  
         [0003]     2. Background Description  
         [0004]     Modern aircraft operate at altitudes at which there is insufficient oxygen to sustain normal human conscious activities. A recent National Transportation Safety Board Aircraft Accident Brief (NTSB/AAB-00/01 at 6, fn 11) provides background information on this topic: 
        Pressurized aircraft cabins allow physiologically safe environments to be maintained for flight crew and passengers during flight at physiologically deficient altitudes. (At altitudes above 10,000 feet, the reduction in the partial pressure of oxygen impedes its ability to transfer across lung tissues into the bloodstream to support the effective functioning of major organs, including the brain. These altitudes are typically referred to as “physiologically deficient altitudes.”) At cruising altitudes, pressurized cabins of turbine-powered aircraft typically maintain a consistent environment equivalent to that of approximately 8,000 feet by directing engine bleed air into the cabin while simultaneously regulating the flow of air out of the cabin. The environmental equivalent altitude is referred to as “cabin altitude.”       
 
         [0006]     Current rules of operation for Transport Category airplanes, FAR 121.333 require a pilot to don and use an oxygen mask whenever the airplane is above 25,000 feet and the pilot is alone on the flight deck, and require at least one pilot to don and use oxygen at all times when the airplane is above 41,000 feet.  
         [0007]     Similarly, for pressurized commuter and on demand aircraft operations, FAR 135.89 require a pilot to don and use an oxygen mask whenever the airplane is above 25,000 feet and the pilot is alone on the flight deck, and require at least one pilot to don and use oxygen at all times when the airplane is above 35,000 feet.  
         [0008]     These requirements exist because external air pressure at cruise altitude is below the oxygen pressure in the pilot&#39;s bloodstream. In the event the cabin lost pressurization, the pilot would rapidly loose consciousness due to hypoxia. The “time of useful consciousness” following a loss of pressurization is shown in Table 1 below.  
                               TABLE 1                               Ambient   Partial   Partial           Time of useful   pressure   pressure of   pressure of       Altitude   consciousness without   of   21% oxygen   50%       (ft)   supplemental oxygen   air (psi)   (psi)   oxygen (psi)                   40,000   15 seconds   2.72   0.57   1.36       35,000   20 seconds   3.45   0.73   1.73       30,000   30 seconds   4.36   0.92   2.18       28,000    1 minute   4.77   1.00   2.39       26,000    2 minutes   5.22   1.10   2.61       24,000    3 minutes   5.69   1.20   2.85       22,000    6 minutes   6.20   1.30   3.10       20,000   10 minutes   6.75   1.42   3.37       15,000   Indefinite   8.29   1.74   4.15                  
 
         [0009]     Source: “Physiologically Tolerable Decompression Profiles for Supersonic Transport Type Certification,” Office of Aviation Medicine Report AM′ 70-12, S. R. Mohler, M. D., Washington, D.C.; Federal Aviation Administration, July 1970.  
         [0010]     An oxygen mask provides a means of supplying 50% or 100% oxygen to the pilot at ambient or near-ambient pressure. Oxygen naturally comprises 21% of the air which, at 15,000 ft., exerts a partial pressure of approximately 1.74 psi. As shown in Table (1) above, the same partial pressure may be provided at 35,000 ft with 50% oxygen, or above 40,000 ft with 100% oxygen (see “Ambient pressure” column above). This is how an oxygen mask provides an extended time of useful consciousness in an unpressurized airplane at cruise altitudes.  
         [0011]     During a decompression event at high altitudes, it is conceivable a single pilot, trying to handle an emergency unassisted, could lose consciousness before he or she would be able to don an oxygen mask. Thus the requirement to wear an oxygen mask for any pilot alone on the flight deck.  
         [0012]     Even with the development of quick-donning oxygen masks, the brief time between a rapid loss of aircraft cabin pressure and the donning and activation of an oxygen mask may be too long to ensure adequate oxygen for the pilot to safely control the aircraft and avoid losing consciousness. As noted by the NTSB: “Research has shown that a period of as little as 8 seconds without supplemental oxygen following rapid depressurization to about 30,000 feet may cause a drop in oxygen saturation that can significantly impair cognitive functioning and increase the amount of time required to complete complex tasks.” NTSB/AAB-00/01 at 34.  
         [0013]     Accordingly, there is a need for improved systems for providing supplemental oxygen to aircraft crew members. The present invention is directed to overcoming one or more of the problems or disadvantages associated with the prior art.  
       SUMMARY OF THE INVENTION  
       [0014]     This invention provides apparatuses and methods for providing oxygen to a pilot or other crewmember in an emergency such as decompression or loss of pressurization, without requiring the pilot to continuously wear an uncomfortable breathing mask.  
         [0015]     Some embodiments of this invention may also be used to provide a self-donning smoke hood function in the event of fire on the airplane.  
         [0016]     The features, functions, and advantages may be achieved independently in various embodiments of the present invention or may be combined in yet other embodiments. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a rear perspective view of a self-donning oxygen mask that may be stowed in a radio headset, in a stowed configuration;  
         [0018]      FIG. 2  is a rear perspective view of the self-donning oxygen mask of  FIG. 1 , in a partially deployed configuration;  
         [0019]      FIG. 3  is a rear perspective view of the self-donning oxygen mask of  FIG. 1 , in a fully deployed configuration;  
         [0020]      FIG. 4  is a rear perspective view of a self-donning oxygen mask that deploys in a clamshell fashion;  
         [0021]      FIG. 5  is a side elevational view of a self-donning oxygen mask that may be stowed in a shoulder harness, in a stowed configuration;  
         [0022]      FIG. 6  is a side elevational view of the self-donning oxygen mask of  FIG. 5 , in a partially deployed configuration;  
         [0023]      FIG. 7  is a side elevational view of the self-donning oxygen mask of  FIG. 5 , in a fully deployed configuration;  
         [0024]      FIG. 8  is a front elevational view of a self-donning oxygen mask that may be stowed in a chest pack or seat belt buckle, in a stowed configuration;  
         [0025]      FIG. 9  is side elevational view of the self-donning oxygen mask of  FIG. 8 , in a stowed configuration;  
         [0026]      FIG. 10  is a side elevational view of the self-donning oxygen mask of  FIG. 8 , in a partially deployed configuration;  
         [0027]      FIG. 11  is a side elevational view of the self-donning oxygen mask of  FIG. 8 , in a fully deployed configuration;  
         [0028]      FIG. 12  is a front elevational view of the self-donning oxygen mask of  FIG. 8 , in a fully deployed configuration and partially disconnected from the seat belts and shoulder harnesses;  
         [0029]      FIG. 13  is a side elevational view of the self-donning oxygen mask of  FIG. 8 , in a fully deployed configuration and completely disconnected from the seat belts and shoulder harnesses;  
         [0030]      FIG. 14  is a front elevational view of the self-donning oxygen mask of  FIG. 8  in a fully deployed configuration, completely disconnected from the seatbelts and shoulder harnesses, and with securing body straps installed;  
         [0031]      FIG. 15  is a side elevational view of a self-donning oxygen mask that may be stowed in a headrest, in a stowed configuration;  
         [0032]      FIG. 16  is a side elevational view of the self-donning oxygen mask of  FIG. 15 , in a partially deployed configuration;  
         [0033]      FIG. 17  is a side elevational view of the self-donning oxygen mask of  FIG. 15 , in a fully deployed configuration;  
         [0034]      FIG. 18  is a side elevational view of the self-donning oxygen mask of  FIG. 15 , in a fully deployed configuration and partially detached from the headrest;  
         [0035]      FIG. 19  is a front elevational view of the self-donning oxygen mask of  FIG. 15 , in a fully deployed configuration and with securing body straps installed;  
         [0036]      FIG. 20  is a perspective view of a self-inflating oxygen mask stowed in a container;  
         [0037]      FIG. 21  is a perspective view of the self-inflating oxygen mask of  FIG. 20 , removed from the container and in a partially deployed configuration;  
         [0038]      FIG. 22  is a perspective view of the self-inflating oxygen mask of  FIG. 20 , in a fully deployed configuration;  
         [0039]      FIG. 23  is a front elevational view of the self-inflating oxygen mask of  FIG. 20 , in a fully deployed configuration and in an operational position over a head of a user;  
         [0040]      FIG. 24  is a perspective view of a self-donning oxygen mask stowed in a bed;  
         [0041]      FIG. 25  is a perspective view of the self-donning oxygen mask of  FIG. 24 , in a partially deployed configuration;  
         [0042]      FIG. 26  is a perspective view of the self-donning oxygen mask of  FIG. 24 , in a fully deployed configuration;  
         [0043]      FIG. 27  is a perspective view of a self-inflating oxygen tent installed on a bed and in a partially open configuration; and  
         [0044]      FIG. 28  is a perspective view of the self-inflating oxygen tent of  FIG. 27 , in a closed configuration. 
     
    
     DETAILED DESCRIPTION  
       [0045]     This invention may include a transparent flexible hood made in one or more parts, and that may be connected to a number of inflatable tubes. The entire assembly may be collapsed into a flat package.  
         [0046]     The invention may include incorporation of a hood into an overall emergency oxygen system for an aircraft such that, for example, when a loss of pressure is detected, a warning alarm sounds. If the pilot does not quickly disarm the system, oxygen or oxygen-enriched air is released into the inflatable tubes, which become rigid, and pull/push the connected oxygen hood from its storage location. The hood may be configured such that when the tubes are fully inflated, the hood closes around the pilot&#39;s head. Oxygen or oxygen-enriched air is released into the hood for the pilot to breathe.  
         [0047]     The hood does not need to seal tightly around the pilot&#39;s head, as the hood is not pressurized. Small gaps around the edges of the hood will not impair function. In fact, small gaps are necessary to exhaust the pilot&#39;s exhaled air. Large gaps, however, may impair function unless the oxygen flow is increased to compensate.  
         [0048]     These self-donning oxygen systems may be configured to deploy automatically, with no input required by the user. Thus, the system will deploy and function even of the user is unconscious. These systems not only deploy and operate on an unconscious user, but supply a sufficient amount of oxygen for the user to regain consciousness and thus, regain control of the aircraft.  
         [0049]     Variations of the self-donning oxygen system according to the invention may include some or all of the features of the following embodiments.  
         [0050]     With reference to  FIGS. 1 through 3 , a transparent oxygen hood  20  may be stowed in a pilot&#39;s radio headset  22 , and deployed forward to cover a pilot&#39;s face  24  when activated by a sensor system  31 . The sensor system  31  is in fluid communication with the cabin atmosphere and monitors the cabin pressure. If the cabin pressure falls below a predetermined threshold, the warning alarm is activated and if the pilot does not disarm the sensor system  31  in a predetermined amount of time, the sensor system  31  activates the transparent oxygen hood  20 . Of course, the sensor system  31  may be remotely located from the transparent oxygen hood  20  and may activate the transparent oxygen hood  20  wirelessly.  FIGS. 2 and 3  depict a deployment of the transparent oxygen hood  20 . The transparent oxygen hood  20  may include inflatable tubes  25  that add rigidity and help give a consistent shape to the transparent oxygen hood  20 . The tubes  25  may be inflated with gas from the aircraft oxygen supply, a separate gas supply, such as, a separate pressurized oxygen tank or a small canister of carbon dioxide (e.g., the small pressurized carbon dioxide canisters used to inflate life vests or used in pellet guns). Of course, other devices may be used to inflate the hood, such as, for example, resilient wires, springs, flexible resilient fabrics, etc. The transparent oxygen hood  20  does not need to seal tightly around the pilot&#39;s face  24  to function properly. This configuration may require the pilot to continually wear the radio headset  22  when alone on the flight deck, in order to comply with aviation regulations.  
         [0051]     The oxygen-enriched air supplied to the transparent oxygen hood  20  may be supplied from one or more small internal cylinders (not shown). The small internal cylinders may contain oxygen-enriched air or may contain 100% oxygen which is mixed with ambient air, using an induction pump (not shown), for example, to produce an oxygen-enriched air supply. This configuration may be incorporated into the headset  22 . However, the small internal cylinders would become depleted over time. At some point after the loss of pressurization, the pilot would have to connect the transparent oxygen hood  20  to an oxygen supply line (not shown), or remove it to don a normal oxygen mask when time permits.  
         [0052]     According to another embodiment of the invention, a transparent oxygen hood  20 ′ may deploy from the radio headset  22  in two parts, closing in a clamshell fashion around the pilot&#39;s head, or head and neck, as depicted in  FIG. 4 . The transparent oxygen hood  20 ′ may include inflatable tubes  25 ′.  
         [0053]     In accordance with yet another embodiment of the invention, depicted in  FIGS. 5 through 7 , a transparent oxygen hood  120  may deploy from a pilot&#39;s shoulder harness  122 . The transparent oxygen hood  120  may be deployed in a single piece, as shown, or in a clamshell fashion similar to that depicted in  FIG. 4 . The transparent oxygen hood  120  may include inflatable tubes  125 . The use of this embodiment may require the pilot wear the shoulder harness  122  continually when alone on the flight deck. The transparent oxygen hood  120 , when stowed, may be integrated into the shoulder harnesses and/or seatbelts  122  or may be attached to the shoulder harnesses and/or seatbelts  122 .  
         [0054]     In accordance with yet another aspect of the invention, a transparent oxygen hood  220  may deploy from a lightweight chest pack  223  (shown in  FIGS. 8 through 14  and similar to a front-pack baby carrier), seatbelt buckle, or other device worn by the pilot. Deployment may be similar to that of the embodiment depicted in  FIGS. 5 through 7 , except the pilot would be able to rise from his seat and take the transparent oxygen hood  220  with him. The seatbelt buckle or chest pack  223  is detachable from the seatbelts  222  allowing a user freedom of movement. This example also includes optional body securing straps  227  to keep the transparent oxygen hood  220  in place during movement.  
         [0055]     With reference to  FIGS. 15 through 19 , a transparent oxygen hood  320  may be stowed in a pilot&#39;s seat  322 , deploying from a head rest  324 . The transparent oxygen hood  320  may include inflatable tubes  325 . This embodiment may require that the pilot remain seated when alone in the flight deck.  
         [0056]     The transparent oxygen hood  320  may deploy from a detachable backpack  329  nestled into the seat cushions instead of the headrest  324 . After deployment the pilot may manually or automatically strap the backpack  329  on and detach it from the seat  322 , thus allowing the pilot to rise from his seat  322  and take the transparent oxygen hood  320  with him. This embodiment may include body securing straps,  327 , similar to the embodiment of  FIGS. 8 through 14 .  
         [0057]     Another related concept for ease of use is a self-inflating, manually donned transparent oxygen hood  420 , as shown in  FIGS. 20 through 23 . This system could replace existing Portable Breathing Equipment (PBE) used by airplane crews for fighting certain types of fires. Conventional PBE systems use a chemical oxygen generator that, once activated, cannot be deactivated and thus runs to depletion. Additionally, such chemical oxygen generators emit significant amounts of heat as a by product of the chemical reaction and this excess heat may become extremely uncomfortable for a user. In this concept, a crewmember needing emergency oxygen removes the flat, un-inflated transparent oxygen hood  420  from a container  421 . Tubes  425  may be provided that inflate in the collar  430  and sides of the hood  420  to give it a helmet-like shape, enabling easy donning and wear.  
         [0058]     This invention may also be used to provide self-donning transparent oxygen hoods for flight attendant seats. If such devices are supplied from detachable backpacks, flight attendants would be assured of ready access to oxygen-enriched air in the event of loss of pressurization, and their mobility to assist passengers would not be impaired. Of course, any or all of the embodiments may be constructed from fire proof or fire resistant materials to protect the face of the user from intense heat and/or fire.  
         [0059]     This invention may also be used to provide self-donning transparent oxygen hoods  520  for crew rest seats and/or beds  532 . This concept would ensure that a crew member seated or lying down during periods of crew rest would be supplied with oxygen-enriched air, for example, in the event of a loss of cabin pressure, even while sleeping, as shown in  FIGS. 24 through 26 . The transparent oxygen hood  520  may be stowed in one or both ends of the crew bed  532  or in the top of a crew rest seat (not shown). Alternately, the transparent oxygen hood  520  may be stowed in a bottom side of the crew bed  532 . Regardless, upon detection of a loss of pressure, the flexible tubes  525  may inflate, similar to the previous embodiments. This example of the transparent oxygen hood  520  may be connected directly to an aircraft oxygen supply or a portable oxygen bottle stored near the crew bed  532  or seat. The transparent oxygen hood  520  extends, as the tubes  525  pressurize, sufficiently to cover the head area of a crew member lying in the bunk. The flexible tubes  525  when pressurized are sufficiently flexible to conform to the crew members body, thereby covering the crew member and able to accommodate a wide range of body sizes and/or shapes.  
         [0060]     A variation of the above concept would supply oxygen-enriched air directly to a crew rest bunk with a tent  620  as shown in  FIGS. 27 through 28 . A simple curtain  634  may be used to constrain the oxygen-enriched air to the bunk  632 . The curtain  634  may be releasably secured to one or more sides of the tent  620  or to the bed  632 . The curtain may be attached with a zipper, hook and loop fasteners, buttons or any other type of releasable securing device. The seal need not be air tight as discussed above.  
         [0061]     A “dump and meter” system may be required to ensure rapid replacement of the air inside the hood or tent with oxygen-enriched air. This system would “dump” a large amount of oxygen for the first several seconds, followed by “metering” a slower flow of oxygen to maintain appropriate levels as the pilot breathes. A system of this sort may be required especially for the larger volume systems, such as the tent systems described above. Although, a “dump and meter” system may be used for the hood type systems as well. These “dump and meter” systems may also assist with deploying the inflatable tubes.  
         [0062]     All of the above embodiments may be optionally provided with a control knob to allow the pilot to adjust the rate of flow and/or oxygen richness. Additionally, oxygen-enriched air may be released into the hood/tent through a dedicated valve, or by controlled leakage from the inflatable tubes.  
         [0063]     The automatic deployment feature may include a wireless link to deploy the hood when smoke is detected on the flight deck by the airplane&#39;s avionics cooling system.  
         [0064]     Other aspects and features of the present invention can be obtained from a study of the drawings, the disclosure, and the appended claims.