Abstract:
Detailed are restraints intended principally (but not necessarily exclusively) for inflatable evacuation slides or rafts. At least one such restraint may be designed to release based on geometric shape of an object (such as a slide) rather than merely as a function of its inflation pressure or length. One version of this type of restraint includes a connector pin attached to a cord, with tensioning of the cord eventually retracting the pin to effect release of the restraint.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to restraints for inflatable materials and more particularly, although not necessarily exclusively, to temporary restraints for inflatable evacuation slides or rafts of the types often installed on aircraft or other vessels or on drilling platforms or other building structures. 
       BACKGROUND OF THE INVENTION 
       [0002]    Inflatable evacuation slides typically are provided as means for emergency egress from aircraft or other people-containing structures. Controlling deployment of these slides so as to allow them to function correctly in emergency situations is thus of especial importance. Deployment control may be difficult in certain circumstances, however; as an example, if extended fully while only slightly inflated, a slide may be vulnerable to wind deflection repositioning its distal end such that the slide is unsuitable for passenger transit even when more completely inflated. Conversely, controls that prevent adequate inflation of a slide likewise would be problematic. 
         [0003]    Conventionally, assemblies of cords and wires, referred to as frangible links, have been used for deployment control. Such a link is placed between proximal and distal ends of a folded, uninflated slide. As the slide inflates, it attempts to unfold but is restrained by the link. Further inflation eventually tensions the wire past its breaking point, at which time the slide may fully unfold for use. 
         [0004]    U.S. Pat. No. 4,460,062 to Fisher describes another restraint system for evacuation slides designed especially for installation in the upper deck of a Boeing 747 aircraft. It replaces the frangible links described above with shear pins. The Fisher &#39;062 patent also details a secondary restraint in the form of a cord laced in a lanyard knot, which cord unlaces upon contact with an inflatable bag. U.S. Pat. No. 4,567,977 to Fisher discloses an alternate secondary restraint including a piston and coil spring. 
         [0005]    U.S. Pat. No. 5,711,495 to Danielson illustrates yet another restraint system for inflatable evacuation slides. This system of the Danielson patent provides friction braking means incorporating spooled webbing. As stated in the patent: “Unrolling of the webbing from the spool permits the controlled extension of the inflated tubes until the full extension of the length of webbing occurs, at which time the webbing pulls free from the spool resulting in the full release of the particular fold being restrained.” See Danielson, col. 4, 11. 26-30 (numerals omitted). 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides alternate restraints to those of the Fisher &#39;062 and &#39;977 patents and the Danielson patent. Unlike the restraints of the two Fisher patents, for example, some restraints of the present invention do not release as a direct function of pin breaking strength or internal slide pressure. Moreover, unlike the restraints of the Danielson patent, the present restraints do not incorporate spooled webbing releasing as a function of slide length. Instead, at least one restraint of the present invention releases based on the geometric shape of a partially-inflated slide or raft, restraining a distal section of a slide until the slide has unfolded to a particular angle (or range of angles). 
         [0007]    Certain presently-preferred versions of slide restraints utilize a frangible link connecting proximal and middle sections of the slide as well as an assembly comprising a strap and a moveable pin connecting the middle section and the distal section. As the slide inflates, the middle section and distal section of the slide unfold from the proximal section but are restrained by the frangible link. Eventually, inflation pressure causes breakage of the frangible link, permitting further separation of the proximal and middle sections. 
         [0008]    The strap and pin assembly restrain the position of the distal section of the slide relative to the middle section until the pin retracts, which in turn frees an end of the strap. Retraction of the pin may occur via tension placed on a lanyard (or other cord or connector) connecting the pin to the proximal section of the slide. Whereas the lanyard initially is slack when the slide is folded, inflation of the slide starts to tension the lanyard. Preferably, however, the lanyard retains at least some slack until the frangible link is broken, so that the pin remains in place. Following breakage of the link, however, the lanyard tenses, triggering retraction of the pin and consequent separation of the distal section from the middle section. 
         [0009]    Although frangible links and strap and pin assemblies comprise presently—preferred restraints, other types of restraints may be employed instead or additionally. Similarly, although preferred placements of the restraints are as described above, restraints may be placed elsewhere instead or additionally (including on each side of a slide). Indeed, persons skilled in relevant fields of endeavor will understand that multiple types and placements of restraints may occur within the scope of the present invention. 
         [0010]    It thus is an optional, non-exclusive object of the present invention to provide restraints for expandable materials. 
         [0011]    It is an additional optional, non-exclusive object of the present invention to provide restraints designed principally for use with inflatable evacuation slides or rafts. 
         [0012]    It is another optional, non-exclusive object of the present invention to provide restraints releasable based, at least in part, on the geometric shape of an object (such as an inflatable evacuation slide). 
         [0013]    It is a further optional, non-exclusive object of the present invention to provide restraints releasable upon triggering by tension of a lanyard. 
         [0014]    It is, moreover, an optional, non-exclusive object of the present invention to provide systems of restraints including both one or more frangible links and one or more assemblies of straps and pins. 
         [0015]    Other objects, features, and advantages will be apparent to those skilled in relevant fields of endeavor with reference to the remaining text and the drawings of this application. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a schematic representation of an inflatable evacuation slide and an associated first type of restraint, with the slide shown at a first stage of deployment. 
           [0017]      FIG. 2  is a schematic representation of the slide and restraint of  FIG. 1  shown with the slide at a second stage of deployment. 
           [0018]      FIG. 3  is a schematic representation of the slide of  FIG. 1  and portions of an associated second type of restraint, with the slide shown at approximately the second stage of deployment. 
           [0019]      FIG. 4  illustrates the second type of restraint shown in a first position. 
           [0020]      FIG. 5  illustrates the second type of restraint shown in a second position. 
           [0021]      FIG. 6  illustrates the second type of restraint shown in a third position. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Schematically illustrated in  FIGS. 1-3  is exemplary slide  10  together with a portion of an aircraft A. Slide  10  preferably is an inflatable emergency evacuation slide of the sort commonly installed on commercial and military passenger and cargo aircraft. Slide  10  need not necessarily be so, however; instead, it may allow evacuation of ships or other vessels, drilling platforms, buildings, or other structures. Alternatively, slide  10  may be a raft, a combined slide and raft, or any object having suitable characteristics useable in conjunction with the present invention. 
         [0023]    Versions of slide  10  may be installed (in aircraft or otherwise) in conventional manners. If installed in aircraft A, slide  10  typically would be folded into a small volume and packed within or adjacent an exit door. If needed to permit evacuation of aircraft A, slide  10  could be inflated automatically or manually, with the inflation forcing the slide  10  to unfold (among other things) as its volume increases. 
         [0024]    As schematically depicted in  FIGS. 1-3 , slide  10  may include proximal section  14 , middle section  18 , and distal section  22 . (Of course, other versions of such a slide may comprise more or fewer sections.) Nevertheless, depicted slide  10  includes at least these sections, with proximal section  14  defining a “head,” or proximal end  26  typically designed to remain attached to aircraft A when slide  10  is deployed. By contrast, distal section  22  defines a “toe,” or distal end  30 , when slide  10  is deployed. 
         [0025]      FIG. 1  illustrates slide  10  at a first stage of deployment. At this stage, upper surfaces  34  and  38  of respective proximal and middle sections  14  and  18  remain connected by restraint  42 , which may (but need not necessarily) be or include a frangible link. Inflation of slide  10 , however, has progressed such that middle section  18  has unfolded to an angle α 1  from proximal section  14 . Restraint assembly  46  (see  FIGS. 3-6 ) continues to connect upper surface  38  to upper surface  50  of distal section  22  at this first stage of deployment. 
         [0026]    A second stage of deployment of slide  10  is shown in  FIG. 2 . At this stage, slide  10  has inflated sufficiently to cause unfolding of middle section  18  from proximal section  14  to an angle α 2  (where α 2 &gt;α 1 ), at which point restraint  42  releases or otherwise becomes non-functional (as, for example, by breakage of a frangible link) and middle section  18  can begin to unfold more fully from proximal section  14 . 
         [0027]    Unfolding of middle section  18  from proximal section  14  to angle α 2  (or approximately so) also may trigger release of restraint assembly  46  so as to allow distal section  22  to begin unfolding from middle section  18 .  FIG. 3  schematically details portions of restraint assembly  46  immediately prior to its release, with cord or lanyard  54  approaching maximum tension when middle section  18  has unfolded from proximal section  14  to an angle α 3 . Presently preferred is that the value of angle α 3  exceed that of angle α 2 , so that restraint  42  releases before restraint assembly  46  does. Persons skilled in the art will, however, recognize that the values of these angles need not necessarily be ordered such that α 3 &gt;α 2 &gt;α 1 . 
         [0028]    Additional components of exemplary restraint assembly  46  are illustrated in  FIGS. 3-6 . Beyond lanyard  54 , assembly  46  may include strap  58 , pin  62 , and connector  66 . In at least some versions of slide  10 , strap  58  comprises webbed nylon, pin  62  is a parachute pin, and connector  66  is a loop of cord. Persons skilled in the art will recognize that other materials and objects may be employed instead, however. 
         [0029]    As shown principally in  FIG. 3 , first end  70  of strap  58  may be attached to middle section  18  along side  72  of slide  10 . Such attachment may occur in any suitable manner as, for example, by a ring and patch assembly bonded to middle section  18 . Second end  74  of strap  58  is not fixed to any portion of slide  10 , instead terminating with loop  78 . 
         [0030]    First end  82  of lanyard  54  may be attached—again in any suitable manner—to proximal section  14  along side  72 . Connected appropriately to its second end  86  may be pin  62 , consistent with  FIGS. 4-6 . Like second end  74 , second end  86  is not fixed to any portion of slide  10 . 
         [0031]    Connector  66  advantageously is fixed to distal section  22  of slide  10 . It may comprise, for example, at least patch  90  bonded to distal section  22  and from which loop  94  protrudes. Loop  94  is designed to receive loop  78 , which in turn receives pin  62 . 
         [0032]    For installation, uninflated slide  10  may be folded at least so that upper surface  50  contacts or is proximate upper surface  38  and upper surface  38  contacts or is proximate upper surface  34 . Loop  78  may be fitted through loop  94  of connector  66 , following which pin  62  may be fitted through loop  78 . Because in the folded state of slide  10  the distance between connector  66  and first end  82  of lanyard  54  is less than the length of the lanyard  54 , lanyard  54  remains slack, consistent with  FIG. 4 . 
         [0033]    Upon deployment slide  10  inflates and, as noted above, commences unfolding. When middle section  18  has unfolded from proximal section  14  to an angle α 3 , lanyard  54  becomes taut and slides out of, and thus retracts from, loop  78 , as illustrated in  FIG. 5 . With pin  62  removed from loop  78 , further inflation causes the loop  78  to slide out of, and thus retract from, loop  94  ( FIG. 6 ), fully releasing restraint assembly  46 . Thus, merely by varying the length of lanyard  54 , assembly  46  may be made to release at different values of angle α 3  as necessary or desired. 
         [0034]    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. Contents of the Fisher &#39;062 and &#39;977 patents and of the Danielson patent are incorporated herein in their entireties by this reference.