Abstract:
A wearable life support system integrates an antigravity compensation apparatus for providing counter-pressures on the human body in response to antigravity conditions with an environmental defense apparatus for providing operational conditions to a human within the life support system. A filtration apparatus removes harmful conditions from breathable gas provided to a human within the system. A temperature control apparatus maintains operational conditions to a human within system. A vision maintenance and protection apparatus is kept clear through use of a demisting apparatus that prevents visual distortion of a visor covering the human visual field. The Demisting apparatus is integratable with a wearable life support system that provides environmental defense and/or antigravity compensation to the human user. A portable environmental apparatus provides ground and back-up life sustaining conditions to a human within wearable life support systems.

Description:
RIGHTS OF THE GOVERNMENT 
     The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to life support systems. In particular, this invention relates to operational readiness and life supporting systems which provide, for example, high performance fighter aircraft aircrew with high antigravity (rapid acceleration/deceleration) protection, environmental (chemical/biological) defense protection (both in the aircraft and on the ground), head and body cooling, and/or visual system demisting. 
     BACKGROUND OF THE INVENTION 
     The life support systems currently used by US Air Force fighter aircrew are a combination of apparatuses that include an anti-gravity suit (which provides counterpressure to the aircrew&#39;s lower body thus preventing pooling of blood in the lower body, one of the adverse effects of sustained acceleration), a counterpressure vest (which inflates to apply pressure to the aircrew&#39;s chest and back thus helping the heart pump blood up to the eyes and brain, inhibiting downward blood flow), a high pressure oxygen mask (which delivers breathing gas to the aircrew) and a helmet with a bladder (which inflates to tighten the mask straps to keep the aircrew&#39;s oxygen mask in position and ensure a good seal). To reduce the thermal burden on the aircrew resulting from all of these components, the aircrew may also wear a cooling vest. 
     A breathing gas terminal block worn on the aircrew&#39;s combat flight uniform acts as a connector between manside components and aircraft equipment. 
     Aircraft equipment typically includes an anti-gravity valve and breathing regulator. When the anti-gravity valve senses increasing pressure beyond the operational threshold level, it pressurizes the aircrew&#39;s anti-gravity suit and sends a signal to the breathing regulator, which increases the pressure of the oxygen-enriched breathing gas distributed by the terminal block to the oxygen mask, helmet bladder and counterpressure vest. The breathing regulator receives oxygen-enriched breathing gas from a main breathing gas supply on the aircraft, such as an on board oxygen generating system (OBOGS). Also included with aircraft equipment is an aircraft mounted filter/blower which directs gas to the cooling vest. 
     Although this life support system provides fighter aircraft aircrew with high gravity protection (known in the art as PBG, or pressure breathing for acceleration protection), and some thermal relief, it provides no environmental defense protection. It would therefore be desirable to integrate environmental (biological/chemical) defense protection with pressure breathing capability and body cooling into a single life support system. 
     Chemical defense protection for aircrew is typically provided by an impermeable butyl rubber hood to which a visor and oxygen mask are integrally attached. The impermeable hood assembly is worn under the aircrew&#39;s helmet. The hood assembly provides chemical defense protection for the aircrew both in the air and on the ground (that is, when the aircrew is going to and from the aircraft). Although the hood assembly provides the aircrew with protection from chemical contaminants, its use can result in problems relating to sweat buildup under the hood, which is uncomfortable for the aircrew, and misting of the hood visor, which diminishes the aircrew&#39;s vision. Such demisting/fogging problems are common in most substantially closed environments incorporating visual systems and/or eye protection (e.g., visors, goggles, glasses, etc.). In addition, as previously indicated, chemical and biological defense protection is not currently integrated with pressure breathing capability into one fighter aircraft aircrew life support system. 
     It would therefore also be desirable to provide demisting capabilities for visual apparatuses, and to provide such capabilities for incorporation into environmental defense and/or antigravity life support systems. 
     It is therefore a feature of the present invention to provide a life support system which provides chemical defense and high gravity protection for the aircrew of a high performance fighter aircraft. A further feature of the present invention is to incorporate in an aircrew acceleration life support system a chemical defense hood assembly which provides chemical defense protection for the aircrew in the air and on the ground. A further object of the present invention is to provide a life support system which includes the capability to demist the aircrew&#39;s visor and cool the aircrew&#39;s head and body. 
     It is an advantage of the present invention that it is usable with the main source of breathing gas on the aircraft (such as an on board oxygen generation system or OBOGS), an aircraft-mounted filter/blower, and a portable filter/blower. A further advantage of the present invention is that it enables the aircrew to obtain demist gas from the OBOGS in the event of filter/blower failure. A further advantage of the present invention is that it enables the aircrew to manually control the source of demist gas. 
     Other aspects and advantages of the invention are set forth in part herein and in part will be obvious herefrom, or may be attained by means of instrumentalities and combinations pointed out in the appended claims. 
     SUMMARY OF THE INVENTION 
     In accordance with the foregoing principles and objects of the invention, a wearable life support system for maintaining the operational readiness of a human user of the wearable life support system is described Although reference is made to “aircrew” and “high performance aircraft” throughout the disclosure, it should be appreciated that the teachings of the preferred embodiments are not limited to use exclusively by aircrew. 
     In a first embodiment of the invention, a wearable life support system, useful for aircrew of high performance aircraft, integrates an antigravity compensation apparatus for providing counter-pressures on the human body in response to antigravity conditions with an environmental defense apparatus for providing operational conditions to a human within the life support system. 
     In another embodiment of the invention, a filtration apparatus removes harmful conditions e.g., chemical and/or biological contaminants from breathable gas provided to a human within the system. 
     Another embodiment of the invention provides a temperature control apparatus for maintaining operational conditions to a human within the system. 
     In yet another embodiment of the invention, an apparatus for ensuring that a clear field of vision for a human is maintained in any vision protective/maintenance gear (e.g., a visor) is disclosed wherein a visor is kept clear through use of a demisting apparatus that prevents visual distortion of a visor covering the human visual field. 
     Another embodiment of the invention integrates the apparatus for ensuring clear vision by demisting into a wearable environmental defense/sustaining system. 
     In another embodiment of the invention, a portable environmental apparatus provides ground and back-up life sustaining conditions to a human within the wearable life support system. 
     Another embodiment of the invention provides a portable apparatus for providing demisting gas to the demisting apparatus. 
     Another embodiment of the invention allows for the manual control of gases within the system. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be clearly understood from the following detailed description of preferred embodiments thereof read in conjunction with the accompanying drawing wherein 
     FIG. 1 is a schematic diagram of a representative integrated antigravity/environmental defense life support system and associated aircraft-based equipment. 
     FIG. 1 a  is a side view of an environmental defense assembly of the invention. 
     FIG. 2 a  is a three-dimensional view of a diffuser portion of a demisting apparatus. 
     FIG. 2 b  is a view inside an environmental defense hood of the life support system incorporating componentry of a demisting apparatus. 
     FIG. 2 c  is a cross-sectional view along line D—D through the diffuser component of the demisting apparatus of FIG. 2 b.    
     FIG. 2 d  is an exploded view of the diffuser portion of FIG. 2 a.    
     FIG. 3 is a front view of an aircrew wearing the chemical defense hood and showing the diffuser which is located under a protective hood. 
     FIG. 4 is a cross-sectional view through a demist/cooling valve of the life support system of the invention. 
     FIG. 5 is a side view of an integrated terminal block of the life support system of the invention showing a manually adjustable switch of the terminal block in a first position. 
     FIG. 6 a  is a side view of the integrated terminal block showing the manually adjustable switch in a second position and showing the flow of breathing gas through the terminal block. 
     FIG. 6 b  is a side view of the integrated terminal block showing the manually adjustable switch in a second position and showing the flow of filter/blower gas through the terminal block. 
     FIG. 7 is a schematic diagram of the life support system and associated ground support equipment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, there is shown a schematic diagram of an integrated antigravity compensation/environmental defense life support system generally designated by the reference numeral  10 . The illustrated life support system  10  is of the type that would be used by aircrew and consists of manside components which connect to aircraft and ground support equipment Manside components are worn by the aircrew and include an anti-gravity suit  12 , counter-pressure vest  14 , and cooling vest  16 . Aircrew may wear an environmental (chemical/biological) sustaining/maintenance and/or defense assembly  18  consisting of a hood  20  to which a visor  22  and high pressure oxygen mask  24  are integrally attached. A newly formulated demisting apparatus comprising a demist/cooling valve  26  is integratable into the environmental defense assembly  18  at hood  20 . As illustrated in FIG. 1 a , a helmet  28  integrated with a pressure bladder  30  is wearable over hood  20 . As shown in FIG. 3, a newly formulated removable diffuser  32  is mounted inside hood  20 . As will be more fully explained, diffuser  32  directs gas across the interior of visor  22  for demisting purposes. Also newly formulated is an integrated terminal block  34 , illustrated in FIG. 1, which is worn on the aircrew&#39;s combat uniform. As will be more fully explained, terminal block  34  distributes breathing gas to mask  24 , counter-pressure vest  14  and helmet bladder  30 , and distributes dermist/cooling gas to valve  26 . As will be further explained, valve  26  directs gas flow for visor  22  demist and head cooling. 
     With respect to the following detailed description with respect to demist capabilities of the diffuser  32  illustrated in FIG. 2 a  and demist-related componentry, general reference is made to aspects of the chemical defense assembly  18  (e.g., hood  20 ). Integration with hood  20  should not be interpreted as a requirement/limitation with respect to demisting capabilities taught herein. Demisting capabilities can be provided by the integration of the diffuser  32  and its related demisting components (browbar  36 , tubing  38 , etc.) with visual systems (e.g., visors, goggles, glasses, etc.) without integration with protective gear (e.g., helmets, protective suits, or the like). Reference will be made to a “visor” or “visual system” herein and throughout the claims, and should be broadly interpreted to extend to visors, goggles, glasses, face shields, and other human-worn vision protective/prosthetic gear. Demisting gas may be provided by a portable apparatus. 
     Diffuser  32  and valve  26  will now be described. As shown in FIG. 2 a , diffuser  32  consists of a browbar  36  connecting to a hose assembly, or tubing,  38 . Browbar  36  is molded into a headband shape to follow the contours of the aircrew&#39;s forehead. As shown in FIG. 2 b , browbar  36  is positioned inside hood  20  above visor  22  such that its outer surface engages the interior surface of hood  20  and its inner surface engages the aircrew&#39;s forehead. As illustrated in FIG. 2 c , browbar  36  includes a molded neoprene rubber member  40  which is substantially rectangular in cross section. An axial passage  42  approximately 0.25 inches in diameter extends through member  40 . A plurality of passages  44  substantially perpendicular to axial passage  42  extend from the bottom of axial passage  42  through the underside of member  40 . Preferably, there are eight passages  44 , each 0.1 inch in diameter, equally spaced along the circumference of member  40 , as shown in FIG. 2 d . A foam member  46  is attached to the inner radius surface of member  40  using Velcro™ hooks  48  (or the like). A piece of cloth  50  is attached to the forehead-engaging surface of foam member  46 . Cloth-covered foam member  46  may thus be easily removed from member  40  for cleaning or replacement. 
     Preferably, cloth  50  is composed of a hydrophilic fabric, such as Ortho-Wick™ manufactured by Guilford Mill, Inc., which acts to wick moisture away from the aircrew&#39;s forehead. Preferably, foam member  46  is composed of a high density, breathable urethane available in thickness of ⅛ inch, ¼ inch, ⅜ inch and ½ inch. This enables the aircrew user to select foam member  46  with an appropriate thickness to provide a desired standoff between the aircrew&#39;s forehead and hood  20 . This is particularly helpful when the aircrew wears spectacles. 
     The outer radius surface of browbar member  40  is attached to hood  20  using fastening tape  52  which is also preferably made of Velcro™. Browbar  36  may thus be easily repositioned or removed from hood  20  for maintenance or cleaning. 
     As shown in FIG. 2 a , hose assembly (tubing)  38  is positioned at one end of browbar  36  substantially perpendicular thereto. Hose assembly  38  is adhesively bonded to the interior surface of hood  20 , along the side of visor  22 . One end of hose assembly  38  is coupled to browbar  36 . An opposing end connects to a spring-operated poppet valve  26  which is integrated into hood  20 , as shown in FIG.  3 . As illustrated in FIG. 4, valve  26  includes a demist outlet  54 , to which hose assembly  38  is coupled, a head cooling outlet  56 , and an inlet  58  which connects to a source of demist/cooling gas, as will be more fully explained. A spring-loaded poppet  60  operates to close valve  26 . When valve  26  is open, demist/cooling gas entering inlet  58  is split between head cooling outlet  56  (providing cooling gas to the aircrew&#39;s head) and demist outlet  54  (where it flows through hose assembly  38  and into axial passage  42  of browbar  36  and is directed through perpendicular passages  44  across visor  22  to demist visor  22 ). When valve  26  is closed, all gas is diverted to demist outlet  54 . Sufficient demist/cooling gas pressure is required to open valve  26 . When pressure drops, poppet  60  closes valve  26  and shuts off head cooling flow, as will be further explained. 
     Terminal block  34  will now be described. As shown in FIG. 5, terminal block  34  includes a central manifold chamber  62  having a main breathing gas inlet port  64  which is coupled to an inlet hose  66 , a filter/blower gas inlet port  68  which is coupled to an inlet hose  70 , a breathing gas outlet port  72 , a demist outlet port  74 , and a vest outlet port  76 . An emergency breathing gas inlet port  78  is connected via a channel  80  to breathing gas outlet port  72 . 
     As illustrated in FIG. 1, breathing gas outlet port  72  connects to the aircrew&#39;s breathing mask  24 . As shown in FIG. 1 a , breathing gas outlet port  72  also connects to helmet bladder  30 . As further illustrated in FIG. 1, vest outlet port  76  connects to the aircrew&#39;s counter-pressure vest  14 , all in a manner well known in the art. Demist outlet port  74  connects via a demist/cooling hose  82  to valve inlet  58 . Breathing gas and filter/blower gas inlets  66 ,  78  and  70  connect to supplies of these gases, as will be more fully explained in the discussion of aircraft and ground support equipment. 
     As shown in FIG. 5, a manually adjustable switch, or valving mechanism,  84  is mounted in central manifold chamber  62  of terminal block  34 . Switch  84  is moveable between a first position illustrated in FIG. 5 and a second position illustrated in FIGS. 6 a  and  6   b.    
     When switch  84  is in the first position as shown in FIG. 5, breathing gas entering breathing inlet  66  flows through central manifold  62  and out of breathing outlet  72  and vest outlet  76 , as indicated by the arrows. Filter/blower gas entering filter/blower inlet  70  flows out of demist outlet  74 , as shown. 
     When switch  84  is in the second position as shown in FIG. 6 a , breathing gas entering breathing inlet  66  flows through central manifold  62  and out of breathing outlet  72 , vest outlet  76  and demist outlet  74 , as indicated by the arrows. Similarly, as shown in FIG. 6 b , filter/blower gas entering demist inlet  70  flows out of demist outlet  74 , breathing outlet  72  and vest outlet  76 . Thus, as illustrated in FIGS. 6 a ,  6   b , in the second position, switch  84  opens a passage  86  for breathing gas to flow to demist outlet  74  and for filter/blower gas to flow to breathing and vest and bladder outlets  72  and  76 . 
     Aircraft equipment connecting to the combined acceleration/chemical defense aircrew life support system will now be described. As illustrated in FIG. 1, in the aircraft, breathing gas and demist/cooling gas inlets are connected to supplies of these gases via a personal equipment connector  88 , which carries all manside/aircraft communication lines, including cooling vest and antigravity suit supplies and intercommunication leads. Personnel equipment connector  88  includes a manside portion  90  and aircraft portion  92  and is mountable on the aircraft seat (not shown). As shown in FIG. 1, main breathing gas inlet  66  is coupled by a series of hoses to a breathing regulator  94  which receives high pressure breathing gas from the main breathing gas supply (not shown). The main breathing gas supply may be an on board oxygen generating system (OBOGS). This breathing gas is filtered by filtering apparatus  96  prior to entering breathing gas inlet  66 . Filter/blower gas inlet  70  is coupled by a series of hoses to an aircraft-mounted filter/blower unit  98  which receives air from the aircraft cabin. Cooling vest  16  also connects via a series of hoses to filter/blower unit  98 . Emergency breathing gas inlet  78  is coupled by a series of hoses to an emergency oxygen reservoir (not shown). Antigravity suit  12  connects via a series of hoses to antigravity valve  100 . Each of these pieces of aircraft equipment (OBOGS, personnel equipment connector, breathing regulator, filter, aircraft-mounted filter/blower, emergency oxygen reservoir, and antigravity valve) are well known in the art. 
     Life support system ground equipment/portable environmental apparatus will now be described. As shown in FIG. 7, on the ground, a portable filter/blower  102  provides demist/cooling gas to the aircrew. Filter/blower inlet  70  is coupled by a series of hoses to portable filter/blower  102 . Portable filter/blowers are well known in the art. It may be desirable to provide for a separate portable apparatus that can exclusively provide demisting/defogging gas to the demisting apparatus. 
     The combined acceleration/chemical defense aircrew life support system will now be described in the context of ground and aircraft operations in order to enable understanding of the invention. 
     During ground operation, the aircrew uses portable filter/blower  102  to provide demist/cooling gas to browbar  36  and cooling vest  16 . As illustrated in FIG. 7, the aircrew connects inlet hose  70  and cooling vest  16  to filter/blower  102 . The aircrew sets switch  84  to the second position, as illustrated in FIG. 6 b , and turns filter/blower  102  on. As illustrated in FIG. 6 b  part of the filter/blower gas entering terminal block  34  will flow from dermist outlet port  74 , where it will be directed to inlet  58  of demist/cooling valve  26 . As illustrated in FIG. 4, valve  26  will split gas flow between visor demist and head cooling. Demist gas will flow through demist outlet  54 , into diffuser  32  and be directed across the aircrew&#39;s visor  22 , as shown in FIGS. 2 a ,  4 . Head cooling gas will flow through head cooling outlet  56  and around the aircrew&#39;s hood  20 , thereby providing cooling gas to the aircrew&#39;s head. Part of the filter/blower gas will also flow from breathing gas outlet port  72  to mask  24  and bladder  30 , as shown in FIG. 1 a.    
     When the aircrew enters the aircraft cockpit, he disconnects inlet hose  70  and cooling vest  16  from portable filter/blower  102  and reconnects inlet hose  70  and cooling vest  16  to aircraft mounted filter/blower  98 , as illustrated in FIG.  1 . In addition, the aircrew connects main breathing gas inlet port  66  to regulator  94  and emergency breathing gas inlet port  78  to a source of emergency breathing gas (not shown), such as an emergency oxygen bottle. As is known in the art, regulator  94  will provide breathing gas to mask  24  through filter  96 . Also, as is known, the emergency oxygen bottle will supply breathing gas to mask  24  when the main source of breathing gas (such as OBOGS) either does not work or cannot supply breathing gas to mask  24 . The aircrew also connects vest outlet  76  to counterpressure vest  14  and antigravity suit  12  to antigravity valve  100 . As is known in the art, when the aircrew is exposed to high gravity, antigravity valve  100  will pressurize antigravity suit  12  and send a signal to breathing regulator  94 , which will increase the pressure of breathing gas distributed to mask  24 , bladder  30  and counterpressure vest  14   
     The aircrew sets switch  84  to the first position, as illustrated in FIG.  5 . The breathing gas entering terminal block  34  will flow from breathing gas outlet port  72  and vest outlet  76  and be directed to mask  24  and counterpressure vest  14 , as indicated previously. The filter/blower gas entering terminal block  34  will flow from demist outlet port  74  and be directed to inlet  58  of demist/cooling valve  26 . As illustrated in FIG. 4, valve  26  will split gas flow between visor  22  demist and head cooling. Demist gas will flow into diffuser  32  and be directed across the aircrew&#39;s visor  22 , as shown in FIG. 2 a . Head cooling gas will flow into the aircrew&#39;s hood  20  through head cooling outlet  56 , thereby providing cooling gas to the aircrew&#39;s head. 
     In the event of aircraft mounted filter/blower  98  failure, the aircrew sets switch  84  to the second position as illustrated in FIG. 6 a . Part of the breathing gas entering breathing gas inlet  66  will flow from breathing gas outlet port  72  and be directed to mask  24  and counterpressure vest  14 , as indicated previously. Part of the breathing gas entering breathing gas inlet  66  will flow from demist outlet port  74 , and be directed to inlet  58  of demist/cooling valve  26 , as illustrated in FIG.  4 . It should be noted that, to maintain PBG performance, passage  86  is dimensioned to restrict the amount of flow diverted from breathing gas for demist to a fraction of the normal input pressure. It must also be noted that the amount of breathing gas allowed through passage  86  is therefore much lower than normally available for demist and head cooling. For this reason, all diverted breathing gas must be used for demist. 
     Spring loaded poppet  60  operates to shut off head cooling in the event of aircraft-mounted filter/blower  98  failure, as illustrated in FIG.  4 . When blower  98  blower is operating, the demist/cooling gas pressure is sufficient to open valve  26 , which operates to split gas flow between visor  22  demist and head cooling, as previously explained. However, when blower gas pressure is not present, spring  104  forces poppet  60  to close. This operates to divert all gas to diffuser  32 , where it directed across the aircrew&#39;s visor  22 , as shown in FIG. 2 a  and as previously explained. 
     It is understood that modifications to the invention may be made as might occur to one with skill in the field of the invention within the scope of the appended claims. All embodiments contemplated thereunder which achieve the objects of the invention have therefore not been shown in complete detail. Other embodiments may be developed without departing from the spirit of the invention or from the scope of the appended claims.