Patent Publication Number: US-9410343-B2

Title: Collapsible frame for a portable shelter

Description:
This application is a continuation in part of U.S. application Ser. No. 13/790,842, filed Mar. 8, 2013, benefit of which is hereby claimed under 35 U.S.C. §120. U.S. application Ser. No. 13/790,842 claims the benefit of U.S. Provisional Patent Application No. 61/651,365, filed May 24, 2012. The present application incorporates both of the above-referenced applications by reference in their entirety. 
    
    
     BACKGROUND 
     Portable shelters are commonly used by the U.S. military and others, and are occupiable for temporarily housing military or other personnel, equipment, and/or supplies, or for providing services such as cooking, dining or medical care. Portable shelters are also used by organizations that provide humanitarian aid throughout the world. Such organizations commonly need to erect portable shelters in areas that have suffered from natural disasters, such as floods, tsunamis, hurricanes and the like. Ideally, these shelters should be designed for storage in a compact configuration that can be easily transported to a new destination for assembly and built for rugged use. Moreover, these shelters should be lightweight to make transportation easier and to make set up and disassembly manageable by a minimum number of people. Preferably, the assembly and disassembly process should be relatively quick and easy and require few hand tools. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of the claimed subject matter will be readily appreciated by reference to the following detailed description, taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is an isometric view of one representative embodiment of a temporary shelter having a collapsible frame formed in accordance with aspects of the present disclosure; 
         FIG. 2  is an isometric view of a collapsible frame of  FIG. 1 , the frame being in an erected state; 
         FIG. 3  is an isometric view of a collapsible frame of  FIG. 2 , the frame being in a first semi-collapsed state; 
         FIG. 4  is an isometric view of a collapsible frame of  FIG. 2 , the frame being in a second semi-collapsed state; 
         FIG. 5  is an isometric view of a collapsible frame of  FIG. 2 , the frame being in a collapsed state; 
         FIG. 6  is an end view of one embodiment of a center frame joint formed in accordance with aspects of the present disclosure; 
         FIG. 7  is an exploded partial isometric view of the center frame joint of  FIG. 6 , the end frame joint being a single purlin joint; 
         FIG. 8  is an isometric view of a pivot pin assembly of the center frame joint of  FIG. 7 ; 
         FIG. 9  is an exploded partial isometric view of the center frame joint of  FIG. 6 , the center frame joint being a double purlin joint; 
         FIG. 10  is an isometric view of a pivot pin assembly of the center frame joint of  FIG. 9 ; 
         FIG. 11  is an end view of one embodiment of a lateral frame joint formed in accordance with aspects of the present disclosure; 
         FIG. 12  is an exploded partial isometric view of the lateral frame joint of  FIG. 11 , the lateral frame joint being joint being a single purlin joint; 
         FIG. 13  is an exploded partial isometric view of the lateral frame joint of  FIG. 11 , the lateral frame joint being joint being a double purlin joint; 
         FIG. 14  is a partial isometric view of a purlin mid joint formed in accordance with aspects of the present disclosure; 
         FIG. 15  is an exploded partial isometric view of the purlin mid joint of  FIG. 14 ; 
         FIGS. 16A and 16B  show isometric views of a rotatable foot in the extended and retracted positions, respectively, formed in accordance with aspects of the present disclosure; 
         FIG. 17  is an example of the temporary shelter of  FIG. 1  equipped with one embodiment of a solar fly in accordance with aspects of the present disclosure; 
         FIG. 18  is another example of a collapsible frame in accordance with aspects of the present disclosure, the collapsible frame disposed in an erected state; 
         FIG. 19  is an end view of an arched frame support formed in accordance with aspects of the present disclosure, the arched frame support disposed in a collapsed position; 
         FIG. 20  is an exploded view of one example of a joint formed in accordance with aspects of the present disclosure; 
         FIG. 21  is an exploded view of another example of a joint formed in accordance with aspects of the present disclosure; 
         FIG. 22  is an exploded view of another example of a joint formed in accordance with aspects of the present disclosure; 
         FIG. 23  is an exploded view of another example of a joint formed in accordance with aspects of the present disclosure; 
         FIG. 24  is a perspective view of one example of a guide pin in accordance with aspects of the present disclosure; and 
         FIG. 25  is a perspective view of one example of a guide pin in accordance with aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In one aspect, the invention relates to a frame support for a portable shelter frame, the frame support being selectively articulable between an erected state and a collapsed state. The frame support includes a central frame member; a pair of upper arcuate frame members rotatably coupled to the ends of the central frame member via first joints, each pair of frame upper frame members being selectively moveable between a first, fixed position when the frame support is in the erected state and a second, fixed position when the frame support is in the collapsed state; and a pair of lower arcuate frame members rotatably coupled to the other ends of the upper arcuate frame members via second joints, each pair of frame lower frame members being selectively moveable between a first, fixed position when the frame support is in the erected state and a second, fixed position when the frame support is in the collapsed state. 
     In another aspect, the invention relates to a frame assembly comprising at least first and second frame supports as just described, and purlin assemblies interconnecting the at least first and second frame supports at the first joints and the second joints, respectively, wherein each purlin assembly includes first and second purlin members rotatably coupled about a purlin mid-joint, a first end of the purlin assembly being pivotally coupled to the first frame support, a second end of the purlin assembly being pivotally coupled to the second frame support, the purlin assembly being selectively lockable in an extended position when the frame is in the erected state, the purlin members being rotatable to a folded position when the frame is in the collapsed state. 
     In another aspect, the invention relates to a frame assembly comprising a plurality of frame supports as just described, and a plurality of purlin assemblies interconnecting respective ones of the frame supports at respective first and second joints, each purlin assembly including first and second purlin members rotatably coupled about a purlin mid-joint, and each purlin assembly being selectively lockable in an extended position when the frame is in the erected state, the purlin members being rotatable to a folded position when the frame is in the collapsed state. 
     In another aspect, the invention relates to a joint for connecting two arcuate frame members, the joint including at least first and second plate members, a pivot pin assembly defining an axis of rotation between the first and second plate members, and a guide pin associated with the first plate member and an arcuate slot disposed in the second plate member, wherein the guide pin travels within the arcuate slot as one of the two arcuate frame members moves between a first, fixed position and a second, fixed position. 
     The detailed description set forth below in connection with the appended drawings where like numerals reference like elements is intended as a description of various embodiments of the disclosed subject matter and is not intended to represent the only embodiments. Each embodiment described in this disclosure is provided merely as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples provided herein are not intended to be exhaustive or to limit the claimed subject matter to the precise forms disclosed. Similarly, any steps described herein may be interchangeable with other steps, or combinations of steps, in order to achieve the same or substantially similar result. 
     The following discussion provides one or more examples of a frame for use with temporary shelters and the like. As will be described in more detail below, embodiments of the frame are collapsible and aid in the quick and easy assembly of a temporary shelter. 
     In the following description, numerous specific details are set forth in order to provide a thorough understanding of exemplary embodiments of the present disclosure. It will be apparent to one skilled in the art, however, that many embodiments of the present disclosure may be practiced without some or all of the specific details. In some instances, well-known process steps have not been described in detail in order not to unnecessarily obscure various aspects of the present disclosure. Further, it will be appreciated that embodiments of the present disclosure may employ any combination of features described herein. 
     Referring now to  FIG. 1 , there is shown an example of a temporary shelter  20  formed in accordance with aspects of the present disclosure. In the embodiment shown, the shelter  20  is of the compact and portable type, and comprises a lightweight, easy-to-erect frame  22  and a durable, flexible, tent-like structure  24  suspended therefrom. The shelter  20  in some embodiments may include a door  26  in the end wall  28 . As will be described in more detail below, the frame  22  is collapsible from an erect state, as shown in  FIG. 2 , to a collapsed state, as best shown in  FIG. 5 . 
     As shown in  FIG. 2 , the frame  22  includes a plurality of lightweight, interconnected frame supports  40 A- 40 F (shown as six) that extend transversely with respect to the longitudinal axis of the shelter  20 . When the frame  22  is erected, the frame supports  40 A- 40 F are vertically aligned, equally spaced apart, and interconnected with adjacent frame supports by a plurality of horizontally aligned purlin assemblies  180 . 
     Each frame support  40  comprises two elongate lateral members  42  and two elongate center members  44 , although different configurations wherein the frame support includes a different number of members are possible. As illustrated, each member  42  and  44  is formed from rectangular metallic tubing, such as rectangular aluminum tubing, so as to provide a lightweight support with sufficient strength to support the shelter  20 . The shape of the members  42  and  44  is not limited to the disclosed rectangular cross-section, but can be round, square, solid, or any other suitable shape. Moreover, while a lightweight metallic material, such as aluminum, is preferred, the members  42  and  44  can be formed of steel, composites, polymeric materials, or any other material having suitable strength. These and other variations as to the form of the members  42  and  44  will be appreciated by those of skill in the art and should be considered within the scope of the present disclosure. 
     In one embodiment, the frame members  42  and  44  and components of the purlin assemblies  180  are constructed out of 6061-T6 or 7075-T6 alloy aluminum tube and/or bar stock. Frame members and components made from 7075-T6 alloy, in particular, have similar strength to those made of steel, but with ⅓ the weight. 
     The center members  44  are hingedly connected end-to-end via a center frame joint  70  or  110  to form an upper frame portion. In the illustrated embodiment, center members  44  form an angle of approximately 140 degrees. The resulting A-frame type structure provides stability to the upper frame portion and to the frame  22  in general. It should be appreciated that the illustrated angle is exemplary only and should not be considered limiting. In this regard, center members  44  can be configured to be aligned, i.e., to form an angle of up to approximately 180 degrees, when the frame is erected. Alternatively, the angle formed by center members  44  can be less than approximately 140 degrees, e.g., 90 degrees or less. Moreover, embodiments are possible in which variation exists among the angles formed by the upper frame portions of different frames  22  that form the frame support  40 . These and other embodiments in which the center members  44  form different angels are contemplated and should be considered within the scope of the present disclosure. 
     Still referring to  FIG. 2 , the opposite end of each of the center members  44  is coupled to an end of a lateral member  42  via a lateral frame joint  150  or  170 . Each lateral member  42  extends to the ground in a downward and laterally outward direction from its respective lateral frame joint  150  or  170 . In the preferred embodiment, each lateral member  42  includes an optional collapsible foot  200  disposed on an end of opposite the connection to the lateral frame joint  150  or  170 . Collectively, the lateral members  42  cooperate to form a lower frame portion that supports the upper frame portion. It will be appreciated that the orientation of the lateral members  42  in the disclosed embodiment are exemplary only and that the angle of each lateral member  42  relative to its associated central members  42  can vary. In this regard, the lateral members  42  can be more vertical or less vertical when the frame  22  is erected. In other contemplated embodiments, the angles formed by associated central members  42  and lateral members  42  can differ for a particular frame support  40  or between different frame supports  40 . 
     A plurality of purlin assemblies  180  couple each frame support  40  to the adjacent frame support or frame supports. For the end frame supports  40 A and  40 F, i.e., the frame supports at the longitudinal ends of the frame  22 , each purlin assembly  180  extends longitudinally toward the adjacent frame support. For the interior frame supports  40 B- 40 E, i.e., the frame supports with an adjacent frame support on each side, a plurality of purlin assemblies  180  extend longitudinally in each direction to couple the frame support to both adjacent frame supports. When the frame  22  is erected, the purlin assemblies  180  ensure proper spacing between the frame supports  40  and also provide longitudinal stability to the frame  22 . 
     As will be described in further detail, each end of a given purlin assembly  180  is coupled to its respective frame support  40  to allow the purlin assembly to rotate relative to the frame support about a longitudinal axis, and to pivot about an axis normal to the longitudinal axis. Although the illustrated embodiment is shown to have purlin assemblies  180  located at the center frame joint  70  and  110  and each of the lateral frame joints  150  and  170 , it will be appreciated that this embodiment is just one example, and that the number of purlin assemblies and the attachment position of each purlin assembly to the frame supports can vary. 
     Referring now to  FIGS. 6-8 , one example of a center frame joint  70  formed in accordance with aspects of the present disclosure will now be described. As shown in  FIG. 6 , the center frame joint  70  maintains the orientation of the center members  44  relative to each other when the frame  22  is erected. As will be explained in further detail below, to facilitate the collapse of the frame  22 , the center frame joint  70  provides for selective rotation of the center members  44  relative to each other until the center members are generally parallel to each other, as shown in phantom lines in  FIG. 6 . 
       FIG. 7  shows a partially exploded isometric view of the center frame joint  70  shown in  FIG. 6 . The center frame joint  70  comprises two outer joint plates  72  and one or more inner joint plates  74 . The outer and inner joint plates  72 ,  74  have substantially identical outer perimeters, forming almost completed cylinders  76  and  78 , respectively, with rectangular-like legs  80  and  82 , respectively, extending at angles therefrom. In the illustrated embodiment, the rectangular-like legs are sized and configured to be received within a center portion of the center members  44 . 
     Each outer joint plate  72  includes a central bore  84  and two outer bores in the form of a purlin pin bore  86  and a lock pin bore  88  aligned on either side of the central bore  84 . The inner joint plate  74  includes: (1) a central bore  90  sized and configured for corresponding with the central bores  84  of the outer joint plates  72 ; (2) an arcuate slot  92  having a diameter corresponding to the purlin pin bore  86  of the outer joint plate  72 ; and (3) a lock pin bore  94  sized and configured to cooperate with the lock pin bores  88  of the outer joint plates  72 . As illustrated, the outer and inner joint plates  72  and  74  include a hole sized and configured to accept a rod  106 , which is inserted into the hole and welded at each end to secure the joint plates  72  and  74  to the center members  44 . Alternate embodiments are contemplated in which the outer and inner joint plates include a plurality of holes for accepting cooperating fasteners for securement to the center members  44 . The legs  80  and  82  may also be secured to respective center members via welding or the like. 
     To assemble the center frame joint  70 , one or more inner joint plates  74  are placed together and aligned. Next, an outer plate  72  is placed on each side of the inner joint plate(s)  74  so that the central bores  84  and  90  align, but with the legs  80  of the outer plates  72  extending in the direction opposite of the leg(s)  82  of the inner joint plate(s)  74 . The inner joint plates  74  are then rotatably connected to the outer joint plates  72  by a cylindrical guide pin  98 . The guide pin  98  is retained therein by snap rings  96  that engage circumferential grooves  100  formed in opposing ends of the guide pin  90 . The guide pin  98  is optionally formed with a plurality of grooves  100  thereon in order to accommodate joints having different thicknesses. 
     A purlin pin assembly  120  has a central portion with a diameter corresponding to that of purlin pin bore  86  of the outer joint plate  72 . The purlin pin assembly  120  extends through the purlin pin bores  86  of the outer joint plates  72  and the arcuate slot  92  of the inner joint plate  74 . The purlin pin assembly  120  is retained therein by snap rings  96  that engage circumferential grooves  124  formed in opposing ends of the purlin pin assembly  120 .  FIG. 8  shows one embodiment of a purlin pin assembly  120  suitable for use with the center frame joint  70  of one of the end frame supports  40 A and  40 F. The purlin pin assembly  120  includes a cylindrical pin  122  with circumferential grooves  124  formed at opposing ends thereof. In the disclosed embodiment, the cylindrical pin  122  has an inner pair of grooves  124  and an outer pair of grooves  124  formed thereon. As with the guide pins  90 , the two sets of corresponding grooves  124  allow a single purlin pin assembly  120  to be utilized in joints having different widths. The cylindrical pin  122  preferably includes a flat portion formed along one side. When utilized with the center frame joint  70 , the flat portion engages a flat portion of the purlin pin bore  86  to prevent the purlin pin assembly  120  from rotating within the purlin pin bore. 
     A lug  126  extends along a longitudinal axis from one end of the pin  122 . The purlin pin assembly  120  further includes a purlin fitting  128  having a cylindrical body  130  with a clevis  132  extending longitudinally from one end. The clevis  132  is sized and configured to engage the lug  126  of the pin  122 . A center pin  134  extends transversely through the clevis  132  and the lug  126  to rotatably couple the cylindrical body  130  of the purlin fitting  128  to the pin  122 . It will be appreciated that the described embodiment is just one example and that other configurations to rotatably couple the purlin fitting  122  to the pin  122  are possible and that such configurations should be considered within the scope of the present disclosure. 
     Referring back to  FIG. 7 , rotation of the center joint  70  is limited by the travel of the purlin pin assembly  120  within the arcuate slot  92 . That is, as the center joint  70  rotates about the axis of the guide pin  98 , the purlin pin assembly  120  moves through the slot  92  until the purlin pin assembly abuts an end of the slot. At this point, the engagement of the purlin pin assembly  120  with the end of the slot  92  prevents further rotation of the center joint  70  in that direction. Thus, the purlin pin assembly  120  limits the rotation of the center joint  70  between a first position, in which the frame  22  is in an erected position, and a second position, in which the frame  22  is in a collapsed position. When the frame  22  is in the first (erected) position, a lock pin  102  is inserted through the lock pin bores  88  and  94  of the outer and inner joint plates  72  and  74  to temporarily fix the position of the center joint  70  in the first position. To move the center joint  70  to the collapsed position, the lock pin  102  is removed, and the center joint is free to rotate to the second position. 
     Still referring to  FIG. 7 , when the center joint  70  is assembled, the purlin fitting  128  of the purlin pin assembly  120  extends outwardly from one side of the joint. The purlin fitting  128  is sized and configured to be received by the cylindrical end of the purlin assembly  180 . With the purlin fitting  128  engaging the end of the purlin assembly  180 , a set pin  104  is inserted into an aperture cooperatively formed by throughbores  136  and  56  that extends laterally through the purlin fitting  128  and the end of the purlin assembly  180 , respectively, thereby pivotally coupling one end of the purlin assembly  180  to the center joint  70 . When coupled to the center joint  70  in this manner, the purlin assembly  180  is free to rotate relative to the center joint about the pivot pin  134  that connects the pin  122  portion of the purlin pin assembly  120  to the purlin fitting  128 . The illustrated center joint  70  is one representative embodiment in accordance with the present disclosure; however, other configurations are contemplated and should be considered within the scope of the present disclosure. In this regard, the described guide pin  98  can be a rivet, bolt/nut, or other fastener that couples the inner and outer joint plates together and provides rotation of each about a center axis. For such configurations, the number and location of the purlin assemblies  180  can vary from the illustrated embodiment 
     Referring now to  FIGS. 9 and 10 , a center joint  110  suitable for use with interior frame supports  40 B- 40 E will be described. Referring to  FIG. 9 , the illustrated center joint  110  is similar to the center joint  70  shown in  FIG. 7 , wherein like reference numbers indicate like components. Unlike the center joint  70  of  FIG. 7 , the center joint  110  of  FIG. 9  uses a purlin pin assembly  140  with a purlin fitting  128  at each end instead of purlin pin assembly  120 , which has a single purlin fitting  128 . 
     As best shown in  FIG. 10 , the illustrated embodiment of the purlin pin assembly  140  includes a cylindrical pin  142  with circumferential grooves  124  formed at opposing ends thereof. Similar to the cylindrical pin of the previously described purlin pin assembly  120 , the present purlin pin assembly  140  has a flat surface that engages a flat surface in the purlin pin bores  86  of the outer joint plates  72  to prevent the purlin pin assembly  140  from rotating relative to the outer joint plates. A lug  126  extends along a longitudinal axis from each end of the pin  142 . The purlin pin assembly  140  further includes a pair of purlin fittings  128 . Each purlin fitting  128  has a cylindrical body  130  with a clevis  132  extending longitudinally from one end. The clevis  132  is sized and configured to engage one of the lugs  126  of the pin  142 . At each end of the pin  142 , a center pin  134  extends transversely through the lug  126  and the clevis  132  of one of the purlin fittings  128  to rotatably couple the cylindrical body  130  of each purlin fitting  128  to an end of the pin  142 . As with the previously described purlin pin assembly  120 , it will be appreciated that the described embodiment is exemplary and that other configurations to rotatably couple the purlin fitting  128  to the pin  142  are possible and that such configurations should be considered within the scope of the present embodiment. 
     Referring back to  FIG. 9 , the center joint  110  is assembled using a guide pin  98  and a purlin pin assembly  140  in a manner similar to the previously described center joint  70  of  FIG. 7 . When the center joint  110  is assembled, a purlin fitting  128  extends from each side of the center joint. Each purlin fitting  128  is sized and shaped to be received within one end of a purlin assembly  180  and to be secured thereto with a set pin  104 . Accordingly, the center joint  110  is capable of having a purlin assembly  180  rotatably coupled to each side of the joint. 
       FIGS. 11 and 12  show one example of a lateral frame joint  150  for use with the end frame supports  40 A and  40 F in accordance with the present disclosure. As previously described, the lateral frame joint  150  rotatably connects one end of a center member  44  to an end of a lateral member  42 . As shown in  FIG. 11 , when the frame  22  is erected, the center member  44  and the lateral member  42  are fixedly positioned relative to each other such that the members form an angle of approximately 110 degrees. It should be appreciated that the illustrated angle is exemplary only and should not be considered limiting. In this regard, the angle formed by a given center member  44  and the corresponding lateral member  42  when the frame  22  is erected can vary to accommodate any suitable frame configuration. As will be explained in more detail later, in order to facilitate the collapse of the frame  22 , the lateral frame joint  150  provides for selective rotation of the lateral member  42  relative to the center member  44  until the lateral member and center member are generally parallel to each other, as shown in phantom lines in  FIG. 11 . 
     Referring now to  FIG. 12 , a representative embodiment of a lateral frame joint  150  will be described. The lateral frame joint  150  includes a pair of joint plates  152  disposed on opposing sides of the end of the end of the lateral member  42 . As illustrated, the joint plates  152  are fixedly coupled to the lateral member  42  using rods  108  welded in place, as previously described with respect to the center frame joint  70 ; however, it will be appreciated that the joint plate can be secured to the lateral member by fasteners, welding, or any other suitable attachment method. When coupled together, the lateral member  42  and the joint plates  152  cooperate to form a clevis on the end of the lateral member. A joint pin bore  154  extends through each joint plate  152  and is positioned to be offset from the edge of the lateral member  42 . Each joint plate further includes lock pin bore  160  formed therein. When the joint plates  152  are coupled to the lateral member, the joint pin bore  154  and lock pin bore  160  of one joint plate align with the corresponding joint pin bore and lock pin bore, respectively, of the opposing plate. As illustrated, the joint plates  152  also include a hole  112  through which a guide wire can be attached to the joint  150  to stabilize the shelter  20 , as shown in  FIG. 1 . 
     Still referring to  FIG. 12 , the end of the center member  44  is formed as a lug  156  with a central bore  158  having a size that corresponds to the joint pin bores  154  of the joint plates  152 . As illustrated, the lug  156  is integrally formed with the center member  44 ; however, the lug can be a separately formed component fixedly secured to the center member using fasteners, welding, or any other suitable attachment method. The center member  44  further includes a lock pin bore  162  that aligns with the lock pin bores of the joint plates  152  when the frame is in an erected position. 
     The lateral member  42  and the center member  44  are rotatably coupled together by the previously described purlin pin assembly  120  extending through the joint pin bores  154  of the joint plates  152  and the central bore  158  of the center member  44 . As previously described with respect to center joint  70 , the purlin pin assembly  120  is retained within the joint by snap rings  96  that are disposed on opposing sides of the joint plates  152  and engage the grooves  124  of the purlin pin assembly  120 . Similar to the previously described purlin pin bore  86  of the center joint  110 , the joint pin bores  154  of the lateral frame joint  150  have a flat portion that engages a flat portion of the purlin pin assembly  120  to prevent the purlin pin assembly from rotating in the hole. 
     When the lateral frame joint  150  is assembled, a purlin fitting  128  extends from one side of the joint to allow a purlin assembly  180  to be pivotally coupled thereto, as previously described with respect to center joint  70  (see  FIG. 7 ). The lateral frame joint  150  is selectively lockable in the erected (open) position by inserting a lock pin  102  though the aligned lock pin bores  160  and  162 . 
     Referring now to  FIG. 13 , an exemplary embodiment of a lateral frame joint  170  suitable for use with interior frame supports  40 B- 40 E, will be described. The lateral frame joint  170  is similar to the lateral frame joint  150  of  FIGS. 11 and 12 , wherein like reference numbers indicate like components. Unlike the previously described lateral frame joint  150 , the lateral frame joint  170  of  FIG. 13  uses purlin pin assembly  140 , which allows a purlin assembly  180  to be pivotally coupled to each side of the joint, as previously described with respect to center frame joint  110  (see  FIG. 9 ). 
     It will be appreciated that the illustrated lateral frame joints are exemplary only and other configurations are contemplated. For example, in one alternate embodiment, the joint plates are couple to the center member, and the lug is formed on the lateral member. In another example, a clevis that engages the lug is integrally formed with either the lateral member or the center member. These and other variations will be apparent to those of ordinary skill in the art and should be considered within the scope of the present disclosure. 
     The purlin assemblies  180  extend longitudinally between adjacent frame supports to maintain spacing between the frame supports and to provide stability to the frame  22  when the frame is erected. Each purlin assembly  180  is pivotally coupled at each end to a frame support. In order to allow for the frame  22  to be collapsed without having to remove the purlin assemblies  180 , each purlin assembly is selectively foldable about a purlin mid joint  184 . 
     Referring to  FIGS. 14 and 15 , one example of a purlin assembly  180  in accordance with the present disclosure will be described. Each purlin assembly includes a pair of elongate members  182 . The elongate members  182  are preferable formed from lightweight hollow tubing, such as round aluminum tubing, but it will be appreciated that the material and cross-sectional properties of the members can vary within the scope of the present disclosure. 
     The elongate members  182  are rotatably coupled about double-hinged purlin mid joint  184 . The purlin mid joint  184  includes center fitting  188  with a pair of lugs  190  extending in opposite directions. Rotatably attached to each lug  189  about a center pin  134  is a previously described, clevis-shaped purlin fitting  128 . Each purlin fitting  128  is in turn received within the end of one of the elongate members  182  and secured therein with a set pin  104 . The disclosed purlin mid joint  184  is just an example, and it is contemplated that various alternate double-hinge configurations can be utilized. Such configurations should be considered within the scope of the present disclosure. 
     A sleeve  186  is slidably associated with the elongate members  182 . When the members are positioned to be approximately coaxial, the sleeve  186  is selectively positionable over the purlin mid joint  184 . When so positioned, the sleeve  186  limits rotation of each elongate member  182  relative to the center fitting  188 , thereby securing the purlin assembly  180  in an extended position (see  FIG. 14 ). When the sleeve  186  is moved so that it does not cover the purlin mid joint  184 , the elongate members  182  are rotatable relative to the center fitting  188  so that the elongate members can be positioned to be generally parallel to each other in a “folded” position (see  FIG. 15 ). Thus, each purlin assembly  180  is selectively positionable between a locked, extended position and a folded position. 
     Referring now to  FIGS. 16A and 16B , a rotatable base  200  is preferable coupled to the lower end of each lateral member  42  to help stabilize the shelter  20 . The rotatable base  200  includes a plate  202  with a pair of lugs  204  extending in a perpendicular direction from opposing sides of the plate  202 . The base  200  is rotatably coupled to the lower end of the lateral member  42  about a bolt, pin, or other suitable element that extends through holes formed in both plates  202  and the lateral member  42 . 
     When the shelter  20  is erected, the base  200  extends laterally from the lateral member  42  and provides a larger “footprint” to support the shelter ( FIG. 16A ). The base  200  is selectively secured in the open position by a removable lock pin  102  that extends through a hole  206  formed in the lateral member  42  and at least one of the lugs  204 . 
     When the shelter  20  is collapsed the lock pin  102  at each base  200  is removed, and the base  200  is rotated into the position shown in  FIG. 16B . The lock pin  102  is then inserted back into the hole in the lateral member  42  for storage. 
     It will be readily apparent to one of ordinary skill in the art that various alternate embodiments of the exemplary disclosed shelter are possible without departing from the spirit and scope of the present disclosure. For example, the number, spacing, and erected form of the frame elements can vary to provide shelters of different sizes and shapes. Moreover, it is contemplated that two or more shelters can be connected end to end, by lateral passageways, or a combination thereof. In this manner, shelters of varying sizes with distinct, separate areas can be configured using a multitude of smaller, standard shelters. These and other variations of the disclosed embodiments are contemplated and should be considered within the scope of the disclosed subject matter. 
     Referring back to  FIGS. 1-5 , one exemplary embodiment of a method for collapsing a portable shelter and, more specifically, a shelter frame, will be described. Starting with the erected shelter  20  of  FIG. 1 , the tent-like structure  24  and associated guide wires, stakes, etc. are removed from the frame, shown in  FIG. 2 . Next, the lock pins  102  are disengaged from the lateral frame joints  150  and  170 , and each lateral member  42  is rotated about the its respective joint until it is generally parallel with the corresponding center member  42 , as shown in  FIG. 3 . Next, the purlin assemblies  180  are unlocked by sliding the sleeves  186  away from the purlin mid-joints. The frame supports  40 A- 40 F are moved together, as shown in  FIG. 4 , with the purlin assemblies  180  folding inward between the frame supports. Finally, the lock pins  102  are disengaged from the center joints  70  and  110 , and the center members  44  are rotated relative to each other until they are generally parallel, as shown in  FIG. 5 . The collapsed frame is optionally secured with straps, placed in a container, or otherwise secured in the collapsed state and is ready for transport. To erect portable shelter, these steps are simply reversed to proceed from the configuration shown in  FIG. 5  to the configuration shown in  FIG. 1 . It will be appreciated that the order of the steps of the described methods are exemplary only and should not be considered limiting. In this regard, the order of the steps may vary within the scope of the present disclosure. 
     The disclosed example of a collapsible shelter is advantageous over known shelters in that it allows for quick set up and disassembly by a minimum number of people. The lightweight construction combined with joints that keep the frame components connected, even when the shelter is disassembled, makes set up and disassembly more manageable so as to require fewer people. In this regard, the disclosed shelter can be easily set up by two or three people or, if necessary, by a single person. Further, the inclusion of lock pins and sleeves to selectively fix the various frame joints in their erected positions eliminates the need for tool and also makes assembly of the frame easier, as these locking devices inherently position the various frame elements when utilized. Moreover, the disclosed frame joints have a limited range of rotation, with the limits of rotation being the erected and collapsed joint positions. These and other disclosed features of the illustrated collapsible shelter combine to provide a shelter that is quickly and easily erected by a minimum number of people. 
     One or more embodiments described herein may be employed with a solar fly, one example of which is sold under the trademark THERMACAM. As best shown in  FIG. 17 , one embodiment of a solar fly, generally designated  220 , includes a durable and flexible outer cover  252 . The outer cover  252  is of sufficient length to completely extend longitudinally over the shelter  20 , as best shown in  FIG. 16 . Also, the outer cover  252  is of sufficient width to extend transversely over the majority of the shelter  20 . In one embodiment, the longitudinal edges of the outer cover  252  are positioned approximately 12-60 inches above ground or other supporting surface. On the outer side of the solar fly  220 , a plurality of guy lines  260  may be employed in order to secure the solar fly  220  over the shelter  20 . The outer side of the solar fly  220  may also be contoured to so as not to hinder use of any doors that are optionally positioned on the side of the shelter. 
     The outer cover  252  in one embodiment is made of one or more layers of solid and/or low or non-gas permeable material such as a polyester reinforced vinyl fabric, military grade canvas fabrics, nylon fabrics, fabrics sold under the trademark CORDURA, military spec. 44103D fabrics, etc. The outer cover  252  includes one or more semi-permeable areas positioned in various locations of the outer cover  52 . In that regard, the outer cover  52  in several embodiments includes one or more longitudinally extending areas  290 A of mesh, such as vinyl mesh fabric, vinyl coated mesh, nylon mesh, military grade mesh fabric, wire mesh, etc., positioned at or near the crest or apex  292  of the roof  94  of the shade shelter  20 . The interstices of the longitudinally extending areas  290 A of mesh are sized and configured so as to permit air flow through the outer cover  252 , and in some embodiments, the interstices may be of a diamond configuration, hexagonal configuration, rectangular configuration, etc., just to name a few. In use, the areas  290 A may act like a vent to allow hot, rising air to escape through the solar fly  220  from the space formed between the outer cover  252  and the tent-like structure  24 , which may in turn, pull cooler air from the bottom of the longitudinal sides and ends of the solar fly, thereby creating convectional air flow sometimes referred to as a chimney effect. 
     In other embodiments, the outer cover  252  may also include one or more longitudinally extending areas  290 B of mesh, such as vinyl mesh fabric, vinyl coated mesh, nylon mesh, military grade mesh fabric, wire mesh, etc., positioned on the sides of the outer cover  52  at approximately the height of any windows of the associated shelter  20 . In some embodiments, the interstices of the longitudinally extending areas  290 B of mesh are sized and configured so as to provide visibility to the occupants of the shelter  24  so that the occupants may see through the windows and out through the outer cover  52 . Additionally or alternatively, the interstices of the longitudinally extending areas  290 B of mesh are sized and configured so as to permit air flow through the outer cover  252 . In some embodiments, the interstices may be of a diamond configuration, hexagonal configuration, rectangular configuration, etc., just to name a few. 
     In several embodiments, the semi-permeable areas, including areas  290 A,  290 B, provide between approximately 55-90% solar protection from the sun&#39;s rays. In one embodiment, the areas  290 A,  290 B provide approximately 85% solar protection from the sun&#39;s rays. In these or other embodiments, an optional blackout layer may be attached along the interior surface of the outer cover  252  other than in the semi-permeable areas, which solely, or in combination with the outer cover  252 , aid in the prevention of light emission through solar fly  220 . In one embodiment, the blackout layer is chosen so that the outer cover  252  provides greater than 80% and up to 100% solar protection from the sun&#39;s rays. One or more materials that can be employed in the blackout layer include but are not limited to carbon, carbon blends, etc. The outer cover  252  may have a camouflaged exterior color that matches the environment, if desired. 
     In a first embodiment, the over cover  252  of the solar fly  220  contacts and is supported by the frame supports  40 A- 40 E. In some embodiments, the solar fly can be spaced from the frame supports by spacers (not shown). Examples of spacers that may be practiced with embodiments of the present disclosure are set forth in detail in Provisional Application No. 61/653,948, filed May 31, 2012, the disclosure of which is hereby incorporated by reference in its entirety. 
       FIGS. 18-25  relate to aspects of another example of a collapsible frame  320  and associated elements and sub-elements, in accordance with aspects of the present disclosure. In some embodiments, the collapsible frame  320  is suitable to support a durable, flexible, outer cover (not shown) in order to form a temporary shelter. In these embodiments, the collapsible frame  320  is of the internal frame type. In other embodiments, the collapsible frame  320  is suitable to support a durable, flexible, tent-like structure suspended therefrom. In these embodiments, the collapsible frame is of the external frame type. 
     In the embodiment shown in  FIG. 18 , the collapsible frame  320  is lightweight and easy-to-assemble.  FIG. 18  shows an end view of the frame  320 ; viewed in plan correspondingly to  FIGS. 1 and 2 , a plurality of arched frame supports  340  (one of which is shown in collapsed form in  FIG. 19 ) would be visible, connected in a corresponding manner and in other ways (one of which is described below) which would be apparent to ordinarily skilled artisans. In  FIG. 18 , the collapsible frame  320  is formed by a plurality of lightweight arched frame supports  340  (one of which is shown in collapsed form in  FIG. 19 , as noted) spaced apart in a transversely disposed manner and interconnected by horizontally aligned purlins. Each arched frame support  340  comprises a plurality (shown as five) arch segments  340 A- 340 E connected end-to-end via joints  348 A,  348 B to form an integral member. In the embodiment shown, arch segments  340 D and  340 E are connected respectively to first ends of arch segments  340 B and  340 C via joints  348 A, while the opposite ends of arch segments  340 B and  340 C are connected respectively to opposite sides of the arch segment  340 A via joints  348 B. 
       FIG. 20  shows an exploded view of one example of the joint  348 A formed in accordance with aspects of the present disclosure. The joint  348 A comprises two outer joint plates  360 A and one or more inner joint plates  362 A. The outer and inner joint plates  360 A,  362 A have a substantially identical outer perimeter, forming an almost completed cylinder with a rectangular-like legs  368 A,  369 A extending respectively therefrom (See  FIGS. 18 and 19 , in which these elements are unnumbered but nevertheless are readily visible). The outer joint plates  360 A each include a central bore  370 A and two outer bores in the form of a guide pin bore  372 A and a lock pin bore  374 A aligned on either side of the central bore  370 A. The inner joint plate  362 A includes: 1) a central bore  380 A sized and configured for corresponding with the central bore  370 A of the outer joint plates  360 A; two outer bores  382 A and  384 A sized and configured to cooperate with the lock pin bores  374 A of the outer joint plates  360 A in the erected position of  FIG. 18  and the collapsed position of  FIGS. 19 ; and 3) an arcuate slot  386 A having a diameter corresponding to the guide pin bores  372 A of the outer joint plates  360 A. The outer and inner joint plates  360 A,  362 A may also include a plurality of holes  388 A for accepting cooperating fasteners for securement to the arch segments  340 A- 340 E. 
     To assemble the joint  348 A, an outer plate  360 A is placed on both sides of the inner joint plate  362 A so that the central bores  370 A,  380 A, are aligned, but with the legs  368 A of the outer plates  360 A extending in the direction opposite of the leg  369 A of the inner joint plate  362 A. The inner joint plate  362 A is then pivotably connected to the outer joint plates  360 A by pivot pin  390 A. Pivot pin  390 A can be a rivet, bolt/nut, or other fastener that couples the inner and outer joint plates together and provides rotation of each about a center axis. In some embodiments, the pivot pin  390 A may be configured similarly to guide pin  98  ( FIG. 7 ). In that regard, the pivot pin  390 A can be retained within joint  348 A by snap rings  398 A that engage circumferential grooves  400 A formed in opposing ends of the guide pin  390 A. The guide pin  390 A is optionally formed with a plurality of such grooves  400 A thereon in order to accommodate joints having different thicknesses. 
     A guide pin  392 A (See also  FIG. 24 ) is then inserted into the cooperating aperture formed by the guide pin bore  372 A and guide slot  386 A. The guide pin  392 A in some embodiments may be configured similarly to cylindrical pin  122  ( FIG. 7 ). Once inserted, the guide pin  392 A can be retained by therein by snap rings  402 A that engage circumferential grooves  404 A formed in opposing ends of the guide pin  392 A. Once the joint  348 A is assembled, the inner joint plate  362 A is allowed to pivot with respect to the outer joint plates  360 A about the center axis formed by pivot pin  390 A from an erected position, such as that shown in  FIG. 18 , to a collapsed position, such as that shown in  FIG. 19 . Once in the extended or erected position shown in  FIG. 18 , a lock pin  394 A, bolt and nut, etc., may be suitably coupled in aligned bores  374 A,  384 A so as to inhibit or lock movement of the inner joint plate  362 A with respect to the outer joint plates  360 A. In some embodiments, the bores  372 A have a flat portion similar to what is shown in  FIGS. 7-10  with respect to purlin pin bore  86  and purlin pin assembly  120 . This type of configuration also may be described as a keyed configuration. Bores  372 A then cooperate with a correspondingly shaped guide pin  392 A so that the guide pin is prevented from rotating, similarly to the arrangement and relationship in  FIGS. 7-10 . 
     The joint  348 A shown in  FIG. 20  is suitable for the end frame supports  340  of the collapsible frame  320 . For the joints of the frame supports  340  positioned in-between the end frame supports, the joint  348 A′ shown in  FIG. 21  can be used. The joint  348 A′ is substantially identical in construction and operation to the joint  348 A of  FIG. 20  except for the differences that will now be described in detail. As shown in  FIGS. 21 and 25 , a guide pin  392 A′ with opposing lugs  126 A′ is employed instead of the single lugged guide pin  392 A of  FIG. 20 . In that regard, the opposing lugs  126 A′ can be employed for coupling to purlins on both sides of the frame support  340 . 
       FIG. 22  shows an exploded view of an example of the joint  348 B formed in accordance with aspects of the present disclosure. The joint  348 B is substantially identical in construction and operation as the joint  348 A of  FIG. 20  except for the differences that will now be described in detail. As shown in  FIG. 22 , the length of the elongate arcuate slot  386 B is less than the arcuate slot  386 A. As a result, once assembled, the inner joint plate  362 B is allowed to pivot with respect to the outer joint plates  360 B about the center axis formed by pivot pin  390 B from an erected position, such as that shown in  FIG. 18 , to a collapsed position shown in  FIG. 19 . Due to the configuration of arcuate slot  386 B and the configuration and arrangement of the joint  348 B, the lock pin bore  374 B and outer bores  382 B,  384 B are located at different positions about the central bores  370 B,  380 B. 
     The joint  348 B shown in  FIG. 22  is suitable for the end frame supports  340  of the collapsible frame  320 . For joints of frame supports  340  positioned in-between the end frame members, the joint  348 B′ shown in  FIG. 23  can be used. The joint  348 B′ is substantially identical in construction and operation as the joint  348 B of  FIG. 22  except for the differences that will now be described in detail. As shown in  FIGS. 23 and 25 , a guide pin  392 B′ with opposing lugs  126 B′ is employed instead of the single lugged guide pin  392 B of  FIG. 22 . In that regard, the opposing lugs  126 B′ can be employed for coupling to purlins on both sides of the frame support  340 . 
     The principles, representative embodiments, and modes of operation of the present disclosure have been described in the foregoing description. However, aspects of the present disclosure which are intended to be protected are not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. It will be appreciated that variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present disclosure. Accordingly, it is expressly intended that all such variations, changes, and equivalents fall within the spirit and scope of the claimed subject matter.