Abstract:
Evacuation systems including slide readiness indicators are detailed. The indicators may include lights colored, preferably, red and green and powered using either pre-existing or dedicated electricity sources. Associated switching equipment defaults to illumination of a red light until a slide is satisfactorily inflated and deployed, at which time the red light is extinguished and a green light is illuminated to provide affirmative indication that evacuation via the slide may commence.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/886,075, filed Oct. 3, 2013, and entitled “Evacuation Slide Readiness Indicator Concept,” the entire contents of which application are incorporated herein by this reference. 
    
    
     FIELD OF THE INVENTION 
     This application relates to systems for evacuating passenger vessels such as aircraft and more particularly, but not exclusively, to inflatable evacuation slides with indicators that the slides are inflated and ready for use. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 4,333,546 to Fisher describes inflatable evacuation or escape slides intended principally for off-wing (or “over-wing”) use. Because the wing may block view of the ground or other support surface from within the aircraft, passengers and crew may be unable to ascertain visually whether an off-wing evacuation slide has inflated sufficient for use. As noted in the Fisher patent:
         It is . . . important for the flight attendant to know whether or not the slide is properly extended without walking to the edge of the wing and looking down. This is important because the attendant must have this information without leaving the fuselage of the aircraft in order to direct the passengers to the escape slides which are operable.
 
See Fisher, col. 1, 11. 13-19. Accordingly, the escape slides of the Fisher patent include two additional indicator tubes designed to inflate upwardly into the line of sight of a flight attendant positioned at the corresponding fuselage access door. The indicator tubes further may include marking tape wrapped around their uppermost ends to enhance their visibility. See id. at col. 3, 11. 38-61. After presumed inflation of a slide, “[t]he attendant then can look out the access door of the fuselage and by observing the positions of the indicator tubes determine if the slide portion, which is not visible from the fuselage, is in condition for evacuating passengers.” See id. at 11. 64-68 (numerals omitted).
       

     U.S. Pat. No. 6,443,259 to Oley discloses a different mechanism for indicating readiness for use of an off-wing evacuation slide. Instead of using the two upwardly-inflatable tubes of the Fisher patent, slides of the Oley patent include
         a conventional red, octagonal “stop” sign that is releasably mounted to the guard rail. The stop sign is removed (to indicate that it is safe to proceed) when the evacuation slide has properly deployed by means of a [lanyard] connected to [the] toe end of the evacuation slide. As the evacuation slide unfurls, the lanyard is paid out until, at the last stage, when the toe end unfurls the lanyard pulls the stop sign off the guard rail, so that it is no longer visible to a disembarking passenger.
 
See Oley, Abstract, 11. 9-17.
       

     Such a stop sign of the Oley patent is made of fabric and removably attached to the guard rail by hook-and-loop fasteners. See id., col. 3, 11. 61-64. Full deployment of the corresponding slide “yank[s the sign] off its mountings” and pulls it into a sheath for concealment and stowage. See id., col. 4, 11. 25-33. Alternatively, the stop sign may be replaced by “a permanent sign which is concealed by a cover operated by a lanyard, or a conventional yellow ‘police tape’ stretching across the entrance [of the slide], which is removed by a lanyard.” See id., col. 4, 11. 53-57. The contents of the Fisher and Oley patents are incorporated herein in their entireties by this reference. 
     As criticized in the Oley patent, the inflatable, upwardly-extending “barber poles” of the Fisher patent are disadvantageous at least because “they use valuable inflation gasses to effect their deployment.” Additionally, they “are not intuitive,” as “self-disembarking passengers will not know to look for the barber poles to determine the status of the evacuation slide and may attempt to exit the plane before the slide is properly deployed.” See id., col. 1, 1. 59 through col. 2, 1. 6. Nor are the stop signs of the Oley patent wholly advantageous, however. Passengers and crew receive no affirmative indication of slide readiness, for example; mere absence of a “stop” sign might not be understood to mean “go,” leading to possible confusion among evacuees as to whether evacuation is yet proper. Additionally, failure of the lanyard to overcome the mechanical strength of the hook-and-loop fasteners, tearing of the fabric of the stop sign, or lack of complete stowage of the stop sign in its sheath may result in continued visibility of some or all of the stop sign even though the corresponding slide is ready for use. This too could confuse passengers and crew, incorrectly inhibiting evacuation when it would be proper to do so. 
     SUMMARY OF THE INVENTION 
     The present invention provides alternatives to the readiness indicators of the Fisher and Oley patents. The indicators not only are intuitive, but also furnish affirmative information as to when evacuation is proper. No valuable inflation gas is needed for operation of the indicators of the present invention, nor is any “yanking” of fabric signs necessary to change states of the indicators from “stop” to “go.” The present invention thus is designed to reduce, if not wholly avoid, evacuee confusion as to readiness of (particularly) off-wing inflatable evacuation slides for use without impeding inflation of the slides in any way. It further may be simple and reliable and use pre-existing electrical power. 
     Presently preferred versions of the invention may comprise colored lights indicating slide statuses. Although such lighting may be supplied in any suitable manner, at least some embodiments of the invention utilize red and green light-emitting diodes (LEDs) to furnish the colored lighting. Nearly universally understood by humans is that a red light is synonymous with a stop command, whereas a green light indicates the contrary (i.e. “go”). Depending on which light is illuminated at any given time, passengers and crew receive clear information—whether negative or affirmative—as to the readiness for use of the corresponding slide. 
     Moreover, some versions of the invention may place the lights on a background shaped like a conventional traffic signal. The signal-shaped background additionally may be of a color contrasting with red and green (e.g. yellow or orange). The effect is to clarify further the function and nature of the lighting as providing stop and go commands for slide usage. 
     Enhanced visibility of the indicator lighting may, if desired, be provided by mounting it on an outboard rail tube at the entrance to the ramp of the slide. This mounting position typically permits easy viewing of the lighting from the fuselage access door or an adjacent window, even in low-light conditions sometimes present in emergency evacuation situations. 
     Readiness indicator lighting of the invention may be powered by, for example, emergency power of the aircraft. Alternatively, batteries used for other aspects of slide lighting may power the indicator lighting of the present invention. No additional power thus is needed to operate the indicator lighting. However, if desired for any reason, the indicator lighting may have a dedicated power supply independent from those typically already present on-board an aircraft. 
     Certain versions of the invention may include a switching module mounted on a lower section of a slide. Upon commencement of slide deployment, electrical power may be supplied to the switching module, whose normal (default) state causes illumination of (only) the red LED. Normal slide inflation causes restraint links to separate sequentially to stage proper unfolding of the slide. As the slide continues to deploy normally, the restraint links continue to separate until a final link remains in the lower section of the slide. If the switching module is connected to or included as part of the final link, separation of the final link may cause the switching module to change state so as to extinguish the red LED and illuminate the green LED instead. Such change in illumination supplies an affirmative signal to passengers and crew that the slide has fully inflated. By contrast, if for any reason the final link does not separate—indicative of improper or incomplete deployment of the slide—the switching module will not change state and the red LED will remain illuminated. 
     Some switching modules may be designed to effect state change through removal of a pin. If the pin is attached to a lanyard in turn attached to a separable portion of the final link, separation of the final link will tension the lanyard and pull the pin from the switching module. As the pin is removed, the switching module changes from its default state (in which the red LED is illuminated) to a state in which the green LED is active and the red LED is inactive. 
     In some circumstances, it might be possible for a slide to deploy completely, hence activating the green LED, yet soon thereafter deflate sufficiently to be unusable. Some versions of the invention, therefore, also may include a pressure sensor which must register satisfactory pressure in the slide before the green LED may illuminate. If at any time slide pressure drops below a minimum acceptable value, the sensor prevents illumination of the green LED or, if the green LED is illuminated, causes a state change so that the red LED becomes active instead. The pressure sensor, if present, preferably is electrically powered, although other sensors of inflation pressure, including transducer-type sensors which may produce electrical signals, may be used instead. 
     It thus is an optional, non-exclusive object of the present invention to provide improved systems for evacuating persons from vessels or other objects. 
     It is also an optional, non-exclusive object of the present invention to provide evacuation systems in which indication of slide readiness is furnished. 
     It is another optional, non-exclusive object of the present invention to provide evacuation systems in which colored indicators of slide readiness are configured to be visible to passengers and crew within aircraft. 
     It is a further optional, non-exclusive object of the present invention to provide evacuation systems not requiring inflation gas or yanking of a fabric sign for purposes of indicating slide readiness. 
     It is, moreover, an optional, non-exclusive object of the present invention to provide evacuation systems in which red and green lights signal, alternatively, “stop” and “go” commands for slide usage. 
     It is an additional optional, non-exclusive object of the present invention to provide evacuation systems in which the signal lights may be positioned on an outboard rail tube at the entrance to a slide ramp and, optionally, with a background of contrasting color shaped as a traffic signal. 
     It is yet another optional, non-exclusive object of the present invention to provide evacuation systems in which indicator lights may be powered by pre-existing sources of electricity. 
     It is also an optional, non-exclusive object of the present invention to provide evacuation systems having switching modules whose states determine which one of a plurality of indicator lights present on a slide is to be illuminated. 
     It is a further optional, non-exclusive object of the present invention to provide evacuation systems in which a switching module is associated with a final restraint link of a slide such that separation of the final link causes the switching module to change states. 
     It is, moreover, an optional, non-exclusive object of the present invention to provide evacuation systems in which the switching module is configured to change states when a pin is pulled therefrom, as by a lanyard tensioned by separation of the final restraint link. 
     It is also an optional, non-exclusive object of the present invention to provide evacuation systems optionally including a sensor for determining that inflation pressure of a slide is (or remains) satisfactory for use. 
     Other objects, features, and advantages of the present invention will be apparent to those skilled in the art with reference to the remaining text and drawings of this application. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1-3  provide various, partly-schematic views of an exemplary inflatable off-wing slide as deployed for purposes of evacuating an aircraft. 
         FIG. 4  illustrates an outboard rail tube of the slide of  FIGS. 1-3  together with an exemplary readiness indicator of the present invention. 
         FIG. 5  is another view of portions of the slide and the readiness indicator of  FIGS. 1-4 . 
         FIG. 6  provides an example of a switching module and final restraint link useful as parts of the slide and readiness indicator of  FIGS. 1-5 , with the final restraint link intact and the switching module in its normal (default) state. 
         FIG. 7  illustrates the exemplary switching module and final restraint link of  FIG. 6 , with the final restraint link separated (i.e. not intact) thereby causing the switching module to change to a state differing from its normal state. 
     
    
    
     DETAILED DESCRIPTION 
     Depicted in  FIGS. 1-3  is exemplary evacuation slide assembly  10 . Slide assembly  10  is shown positioned in part on wing W of aircraft A and thus is commonly called an “off wing” (or “over wing”) assembly. Slide assembly  10  may comprise multiple inflatable tubes  14  and sliding surface  18  and be divided into a generally horizontal entrance section  22  and a ramped section  26  having lower section  28  terminating at toe end  30 . Beneficially, when slide assembly  10  is deployed for evacuation of aircraft A, toe end  30  will be adjacent ground G or some other surface capable of supporting evacuees. 
     However, as illustrated especially in  FIG. 3 , view of lower section  28  (including toe end  30 ) from within aircraft A may be blocked by wing W. Thus, absent exiting the aircraft A via hatch door D and walking to entrance section  22 , passengers and crew may be unable to ascertain whether, in particular, toe end  30  is inflated and positioned properly for use. In darkness or low-light conditions, furthermore, it may be impossible to assess the condition and positioning of lower section  28  even after exiting aircraft A onto entrance section  22 . 
       FIGS. 4-5  show a solution to this issue in the form of readiness indicator  34 . Indicator  34  preferably (although not necessarily) provides visible indication of the deployment status of slide assembly  10 ; visible indications further are preferably of high brightness to counteract external darkness or low-light conditions. Indicator  34  may be mounted, or otherwise attached or connected, to slide assembly  10  in any appropriate manner. As illustrated in  FIG. 4 , indicator  34  preferably is permanently attached to an outboard rail  38  of entrance section  22  so as to be readily visible from hatch door D or nearby windows of the fuselage of aircraft A. 
     At least some versions of indicator  34  include first and second components in the form of lights  42  and  46 . One of these lights beneficially may be a red LED ( 42 ), whereas the other may be a green LED ( 46 ). The colors red and green may be chosen because of their near-universal signification of the commands “stop” and “go,” respectively. Those skilled in the art will, though, recognize that indicator  34  need not provide visual indication or, if it does, that such visual indication need not necessarily be in the form of red and green lighting. Nevertheless, if present, lights  42  and  46  optionally may be backed by a contrasting colored structure or material  50  shaped in the form of a traffic signal, thereby reinforcing the “stop” and “go” command meanings of the red and green colors. 
     Lights  42  and  46  may be powered in any appropriate manner. Aircraft emergency power may be used, for example, as may power potentially available for lighting other aspects of slide assembly  10 . Alternatively, one or more batteries or other power sources may be dedicated to powering lights  42  and  46 . Switching module  54  (see  FIGS. 6-7 ) may be employed to illuminate one or the other of lights  42  and  46 —but preferably not both concurrently—depending on a condition of slide assembly  10 . For example, switching module  54  may have a default state in which, upon deployment of slide assembly  10 , power passes to illuminate red light  42 . When slide assembly  10  is inflated sufficiently for use, switching module  54  may be caused to change state such that power passes to illuminate green light  46  instead. In this way, passengers and crew can be made to comprehend not to evacuate aircraft A when red light  42  is illuminated and to begin evacuating when the red light  42  is extinguished and green light  46  is illuminated. 
     Switching module  54 , while directly or indirectly electrically connected to lights  42  and  46 , beneficially may be mechanically connected to final restraint link  58  of slide assembly  10 . As assembly  10  inflates for deployment, multiple restraint links may separate sequentially in controlled fashion so as properly to stage the unfolding of the assembly  10 . By associating switching module  54  with final restraint link  58 , allowing separation of that final restraint link  58  to effect a change of switching module  54  helps ensure such change occurs only when slide assembly  10  has inflated properly. 
     As shown in  FIG. 6 , final restraint link  58  is intact, and lanyard  62  is connected to pin  66  of switching module  54 . As final restraint link  58  separates ( FIG. 7 ), lanyard  66  is tensioned until the force pulls pin  66  from switching module  54 . Switching module  54  is configured such that removal of pin  66  effects the state change (i.e. toggles the switch), removing power from red light  42  and supplying power to green light  46 . By contrast, should slide assembly  10  not deploy properly such that final restraint link  58  does not separate, power never will be furnished to green light  46  but instead will be provided to red light  42  as long as power is available to switch module  54 . 
     The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of the present invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of the invention. As a non-limiting example of an acceptable adaptation, embodiments optionally may include a pressure sensor which must register satisfactory pressure in the slide to commence or maintain illumination of green light  46 .