To be efficient, portable deployable building assemblies should have a foldable capability so that they may be erected where desired and, when necessary, folded up to a compact form for storage and/or transportation. These types of portable building assemblies now generally utilize struts, which are some type of tubular rods, as the basic construction unit, that form the skeleton structure and thus the configuration of the portable building assembly. The tubular rods noted above are interconnected with one another by some type of linking joints, so that the completed structure is collapsible. A plastic, canvas or some other type of durable fabric covering is secured to the outside and, in many instances, to the inside of the erected structure to envelope the outside surface of the assembly and provide an insulating air space between the covers to form a wall type interior in the covered shelter.
The simplest version of a portable shelter assembly is the “pup tent” noted above which contains two sides configured to form an inverted “V” wherein the vertex at the top can range between 30° and 60° depending upon the desires of the user as to the amount of space present within the interior of the shelter, as shown in FIG. 18.
An example of a large collapsible structure is shown in U.S. Pat. No. 3,185,164, which discloses a portable structure having a plurality of rods joined by coupling means into groups of three which are inter-related to form a generally hexagonal structural system.
Another example of such a collapsible structure is shown in U.S. Pat. No. 3,710,806. Portable structures that utilize elements which maintain the rigidity of the structure are disclosed in U.S. Pat. No. 3,063,521.
For example, U.S. Pat. No. 3,968,808 discloses a collapsible self-supporting dome-like structure with a network of pivotal rods interconnected with linking joints. The linking joint holds six rods, each connected to a six-sided metal ring. Each rod is connected onto the ring and is capable of rotating. The rod is a permanent attachment and thus cannot be disconnected nor replaced. There does not appear any way to attach a cover to the dome-like structure such as is found in the “keeper” component in the articulating hub assembly of the present invention.
U.S. Pat. No. 4,026,313 also discloses a collapsible self-supporting dome-like structure with a network of pivotal rods interconnected with linking joints. The pivotal device linking the rods together forming the structure is a circular joint. Each joint has only four rods. Each rod contains a plug ending with a small cylinder. This small cylinder is nested inside the joint and allows the rod to rotate. It appears that none of the components is easily interchanged. The top and bottom sections of the hubs in the reference appear to be permanently joined by all adhesive so that none of the rods or plugs can be replaced.
U.S. Pat. No. 4,512,097 discloses a display panel mounting clip. The clip body is used to connect display panels together. The clip assembly disclosed requires a spring mechanism to create tension and hold the panels together. The present invention requires no springs. The clip disclosed in the reference must be snapped into an opening joining the rods in a circular joint. In the present invention, the circular hub is screwed into the hub section so it is threadedly secured.
U.S. Pat. No. 4,280,521 discloses a hub assembly for collapsible structures. The hub assembly disclosed in the reference requires a circular retaining ring to hold the “column like elements” or tubes in place. Each tube must be threaded onto a circular retaining ring prior to insertion into the hub section. In the present invention no circular ring is present or required to hold the rods together inside the hub to allow rotation. The present invention as explained in detail hereinafter requires that each tube have its own tang, each with its own roll pin to independently nest inside the hub body. Thus no ring is present. The hub sections are secured in place by use of an adhesive to fuse the two hub sections together permanently. The tube members within the structure, therefore, are not easily replaceable since the hub sections cannot be replaced without destroying them. It is an object of the present invention to provide a hub assembly that has the capability of quickly and easily removing the strut which is contained within the hub.
The '521 reference design described above, uses a three piece clamping device to hold or attach a skin or cover to the structure. One piece is a plug that is incorporated inside the hub section and is fused into the hub sections. The second piece is a flat disc. The third piece is an element which is a screw. The screw is threaded into the plug and holds the clamp down. A screw driver would obviously be required to remove the clamp if or when the cover, the skin or the tubes have to be replaced.
Soviet Patent No. 1,392,220 discloses a joint between rods which possesses two pressure plates whose surfaces face each other and have spherical loons with slits from each loon to the outer outline of the pressure component plate. Screws appear to join the upper plate with the lower plate to hold the ball joints in place. The reference does not disclose a hub assembly such as described and claimed herein.
Collapsible frame structures for supporting tents or other outdoor shelters are disclosed in U.S. Pat. Nos. 563,376; 927,738; 1,773,847, 2,781,766, 3,968,808; 4,026,313; 4,290,244; 4,437,275; 4,473,986; 4,512,097; 4,522,008; 4,561,618; 4,579,066; 4,607,656 4,641,676, 4,689,932, 4,761,929, 4,779,635 and 4,838,003.
The prior art large structures disclosed in the references cited above in the past have suffered from a variety of problems. Some of them are not portable, and some are not collapsible. Due to the immense size which is needed in many present military and civilian applications, it is often difficult to erect or collapse (i.e., to raise or to lower) the structure network formed from the connecting struts. The inherent difficulties are that to erect or to collapse a large volume portable structure requires many workers, takes a significant amount of time, and requires special tools and equipment. The structures are bulky and heavy and have a complicated construction. Deployable portable building assemblies must be capable of being collapsed quickly and easily folded up into a compact structure.
The type of building assemblies using the central hub disclosed in U.S. Pat. No. 5,797,695 ('695) to A. Jon Prusmack, the contents of which are hereby incorporated by reference herein, conveniently collapse to a bundle having a cylindrical configuration along its longitudinal axis when stored.
A front view cross-sectional representation of the shelter structure disclosed in the '695 patent is depicted in FIG. 1A which shows the shelter with five “sections” or “quads” (denoted 1-5). The quads (also referred to herein as sections or modules) are square and have side and diagonal elements formed from tubular strut elements connected at each end and in the center to a hub. The diameter of the tubular strut elements contemplated by the '695 patent is about ⅝″ (0.0625″ in). Each of the five sections found in the '695 prior art structure is 5 feet square. The structure in the embodiment depicted in FIG. 1A has a horizontal interior distance at ground level between quad 1 and quad 5 of a bit greater than 11 feet. Using the 5 ft2 quad dimensions and the tubular strut of ⅝″, when the structure is erected, the distance from the ground to the center point of quad 3 of FIG. 1A is in excess of about 8 feet.
However, when attempting to construct a portable building assembly having greater height, width and length dimensions compared with those dimensions disclosed above with respect to the '695 assembly, it was determined that serious problems were encountered with respect to the structural integrity of the shelter.
When forming a larger interior volume deployable structure than that disclosed in the '695 patent, a tubular strut having greater structural integrity is required than the structural integrity of struts having a diameter of ⅝″. Using a larger diameter strut with the same size hub as disclosed in the '695 patent will not produce a shelter possessing the required features necessary for prompt tactical deployments. An increased diameter strut (i.e., greater than ⅝″) used in combination with the prior art hub will not allow the struts to compress when collapsing the structure. Accordingly, the structure cannot be folded to possess the required “low racking volume” wherein V=⅓πr2h where the smaller the V value, the more efficient the system.
A front cross-sectional view of a larger shelter unit is depicted in FIG. 1B. It possesses quads I-VII. This shelter has widths ranging generally from about 18 feet up to about 32 feet. There is accordingly a wider horizontal space at the base of same between the interior sides I and VII than the eleven plus feet of the shelter disclosed in FIG. 1A. The increased building dimensions require a commensurate increase the diameter of the tubular struts comprising the quads in the construction of a larger deployable shelter. The increase in the diameter of the struts is required as a result of an increase in the stress on the struts. The larger struts result in added structure weight. In addition to the heavier weight of the structure, there are some substantial construction problems. If the larger diameter tubular strut is increased to a length of, for example, 7 feet, the complementary angles between quads I and II, II and III and III and IV, etc. will be changed, so the symmetry which is inherent in the '695 prior art shelter is lost and the structure is totally different.
In copending application Ser. No. 11/228,651 certain basic features of a different style articulating hub assembly with a double tang is also disclosed. As noted, that application is incorporated by reference herein.
In all of the dome or cylinder framework structures of the above prior art patents, movement from the collapsed condition to the expanded condition involves expansion of the base of the structure from a bundled condition outwardly toward and finally to the fully expanded position of the base. Conversely, when the structure is collapsed, the base retreats inwardly from the fully expanded position to the bundled condition. Expansion is effected by pushing upwardly on the center of the structure allowing the sides to slide inward, and the base of the outermost quad to be parallel to the ground. Collapsing is effected by pulling outward on the outermost quad to make it perpendicular to the ground.
In many of the aforesaid prior art patents, as in the present invention, the skeletal framework is covered with flexible waterproof covering material to provide a covering enveloping the structure to result in the shelter function. The covering material may be made of any suitable coated fabric, such as polyester, nylon or even an appropriately treated canvas, and can be one piece and may include flaps with zipper or similar edge connections means for covering any openings or the like. Preferably, the covering material is attached to the framework at the hub means in the manner disclosed in any one of the prior patents. In order to allow the arch portions of the framework to separate for expansion or collapsing, the covering is also provided for such separation, even through it may be zipped up to effect the proper covering function when the framework is expanded.
Because the covering is a fabric, it has a given modulus of elasticity. This elastic property of the fabric presents a problem when a shelter of large area is erected because at the top of the shelter when the fabric cover is under tension, rain or snow falling on the top surface of the covering fabric (which is initially taut) will tend eventually to weigh down the fabric to the point where it will sag and then will collect the rain or snow in pockets formed as a result. As more of the rain or snow collects in these pockets, the greater the added weight to the shelter and ultimately, the overall integrity of the shelter is compromised. The floating hub of the present invention addresses this problem and provides a continuously smooth contour to the top of the shelter so as to eliminate the problem associated with the pockets of water or ice on the upper surface (top) of the shelter. None of the references cited above disclose the use of a floating hub to eliminate the problem stated.
For reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an improved portable shelter without the disadvantages inherent in the prior art.