US 3828501 A
Apparatus is disclosed comprising a holddown device for anchoring an inflatable thin wall structure which encloses a high humidity environment and simultaneously collecting the condensate formed on the inside of the wall of the structure. The device is elongate and contains means for attachment of the structure canopy and a longitudinal groove for collection of the condensate. Openings are provided for removal of the condensate from the collection groove. Anchoring means to attach the device to underlying earth or other support structure is also disclosed. The crosssectional shape is preferably generally triangular.
Description (OCR text may contain errors)
United States Patent [191 Haskins Aug. 13, 1974 APPARATUS COMPRISING A HOLD-DOWN DEVICE  Inventor: Lewis B. Haskins, Littleton, Colo.
 Assignee: Johns-Manville Corporation,
Greenwood Village, Colo.
 Filed: Sept. 10, 1973  Appl. No.: 395,476
 US. Cl 52/303, 52/2, 52/23, 52/l98, 52/295, 52/585  Int. Cl E04b 1/345  Field of Search 52/2, 198, 117, l3, 14,
52/15, 222, 292, 293, 295, 3, 4, 23, 169, 302, 303; 135/15 R, 15 CF; 160/392, 395
 References Cited UNITED STATES PATENTS 2,914,776 l2/l959 Hotz 160/395 X FOREIGN PATENTS OR APPLICATIONS 21l,738 5/1960 Austria 52/23 Primary Examiner-John E. Murtagh Attorney, Agent, or FirmRobert M. Krone; James W. McClain [5 7 ABSTRACT Apparatus is disclosed comprising a holddown device for anchoring an inflatable thin wall structure which encloses a high humidity environment and simultaneously collecting the condensate formed on the inside of the wall of the structure. The device is elongate and contains means for attachment of the structure canopy and a longitudinal groove for collection of the condensate. Openings are provided for removal of the condensate from the collection groove. Anchoring means to attach the device to underlying earth or other support structure is also disclosed. The crosssectional shape is preferably generally triangular.
12 Claims, 13 Drawing Figures PATENIE AUG 1 3mm sum 1 or 3 PAIENIE Am; 1 3 I974 sum 2 or 3 42. 44 N w H APPARATUS COMPRISING A HOLD-DOWN DEVICE BACKGROUND OF THE INVENTION The invention herein relates to apparatus comprising hold-down devices for inflatable thin wall structures. More particularly, it relates to such devices especially suited for use with a structure which encloses a high humidity environment where condensation occurs on the inside of the structure wall.
In recent years inflatable thin wall plastic structures or buildings have come into wide use in many areas. Since they are inflatable and their structural shape is thus maintained solely by air pressure they have found wide use where it is desired to enclose areas where structural support columns, beams, etc., would be impractical; typical of such uses is as enclosures for swimming pools. Since the plastic walls are thin and may be clear or translucent, inflatable structures have also been widely used for greenhouses, being far easier to.
erect and less susceptible to damage than the conventional glass walled greenhouse. There have also been many other uses for the inflatable structures, such as temporary storage facilities.
Two problems have been found to exist with such inflatable structures, however: 1) Because they are thin walled and flexible it has been found difficult to anchor them firmly to the ground or other underlying support structure in a mannerthat will prevent wind lift of the edges. Such wind lift can not only twist and tear the thin plastic wall but also provides entry into the enclosure for dirt, sand and water. Also, and most importantly, wind lift tends to deflate the structure. 2) Where the structure is used to enclose high humidity environments such as swimming pools or the growing facilities of greenhouses, a considerable amount of condensation forms on the inner surface of the thin plastic wall. This condensation tends to run down the inner surface of the wall and collect at the lower edge thereof. Collection and removal of this condensate is thus a continuing concern.
OBJECTS OF THE INVENTION It is the object of the invention herein to provide apparatus comprising a hold-down device which is simple in structure but which will serve to firmly anchor the wall of a thin wall inflatable structure to an underlying support structure.
It is also an object of this invention to provide apparatus comprising a hold-down device which will be resistant to wind lift, easily handleable and may be readily and economically fabricated in large quantities.
It is further an object of this invention to provide apparatus comprising a hold-down device which will simultaneously serve as a collection and removal means for condensate which collects on and runs down the inside walls of such thin wall structures in high humidity environments.
It is further an object of this invention to provide apparatus comprising a hold-down device which may be readily and compactly stored and transported.
BRIEF SUMMARY OF THE INVENTION The invention herein is apparatus comprising a holddown device for anchoring a side of a thinwalled inflatable structure which encloses a high humidity environment and for simultaneously collecting condensate which is deposited on the interior of the wall of the structure. The device comprises an elongated hollow member having an axial opening therethrough in which the condensate accumulates and through which it is removed to a reservoir, drain, or other removal system. The device also has a base portion, an outer wall, and a collector surface. The outer wall has therein canopy attachment means, preferably a longitudinal groove having a cross-section with a maximum width greater than the width of the opening of the groove in the surface of the outer wall. The collector surface has therein a longitudinally extending condensate collection groove. Means are provided for communication between the condensate collection groove and the axial opening. In other embodiments the apparatus also comprises means for attaching the hold-down device to an underlying support structure, means to join adjacent devices together in end-to-end relationship, means cooperating with the canopy attachment means to attach the wall of the structure to the device, and means to provide a pressure differential or suction through the axial opening. It is preferred that the device has a triangular cross-section.
v BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a single section of an having the preferred triangular cross-section.
FIG. 2 is a cross-sectional view of the hold-down device of FIG. 1 taken on the plane 2-2.
FIG. 3 shows pictorially a method of joining together adjacent hold-down devices in end-to-end relationship.
FIG. 4 is an axial cross-section of the devices of FIG. 3 showing the relationship of the various parts in assembled position. I
FIG. 5 illustrates a connection where two devices meet at right angles, as at the corner of a structure.
FIG. 6a shows a means of sealing the outer surface of a device at a joint, and FIG. 6b shows the sealing tape used therefore.
FIG. 7 shows an end view of a number of hold-down devices in a close-packed configuration for storage or shipping.
FIGS. 8 and 9 illustrate two means of anchoring the device to an underlying support structure.
FIGS. 10 and 11 illustrate other means of anchoring the hold-down device to an underlying support, and are particularly directed to embodiments in which the hold-down device is anchored to sand, soil or the like.
FIG. 12 is a detailed drawing showing one means of attaching the wall or side of the canopy of the structure to a hold-down device.
DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS The apparatus of this invention is best understood by reference to the attached drawings. FIG. 1 illustrates in perspective a single length or section of the central element of the apparatus, an elongated hold-down device. Since these devices are most conveniently produced by extrusion, as will be discussed below, the length of a given section is entirely arbitrary and can be chosen on the basis of ease in handling, weight or the particular length needed for a specific use. It is expected that common lengths would typically run up to as much as 20 or 30 feet, depending on the particular material from which the device is made. Shorter lengths such as 6, ID or 20 feet are also contemplated as well as longer lengths where long unbroken stretches of anchoring device are desired and suitable handling means are available. Conversely, very short sections may also be manufactured or can be readily obtained by cutting standard length sections in the field. Similarly, either field or factory cutting can be used to form the mitered ends used for the angular joint shown in FIG. 5.
The specific features of the device and their operation are best illustrated in FIGS. 1, 2 and 12. The device as shown in these Figures (and designated 2) has a generally triangular crosssection. By generally triangular is meant that the overall cross-sectional envelope has the shape of a triangle. The preferred triangular shape will be an isosceles or an equilateral triangle, but any generally triangular shape in which the inner and outer sides have sufficient slope to function effectively herein will be suitable. This triangular shape of the envelope is best illustrated in FIG. 7. In that figure, the triangular outline of each device is evident despite the fact that each has a number of grooves, indentations and rounded corners. This generally triangular shape has been found to be of considerable advantage, for it permits ready attachment of the canopy and to an underlying support structure as well as efficient collection of the condensate and convenient storage. For this reason the generally triangular cross-sectional configuration is preferred. It is also contemplated, however, that other suitable crosssections may be used, such as square, hemispherical, or polygonal. The particular cross-section will be such as to provide a base, an outer wall and a collection surface, each of which will be described below, as well as allowing space for an axial opening.
The device has a base 4, a collection surface 6 and an outer wall 8. Running axially entirely through the device is a central opening 10 which permits the device to function as a pipe.
The outer wall of the device contains canopy attachment means. While such means may comprise clamps, a bar bolted to the outer wall 8, or other such mechanical devices, or chemical adhesives, it is preferred that the means comprise a longitudinal groove 14 formed in outer wall 8. This structure is preferred because it can provide continuous attachment along the length of a section of the device, and also because it is amenable to formation by extrusion. Preferred canopy attachment groove 14 has a crosssectional form such that the maximum internal width is greater than the opening from the surface of the outer wall 8. Resulting from this shape are lips 16 and/or 18. Attachment of the canopy, side, or wall of the structure is by force-fit or pressure fit, as shown in FIG. 12. A compressible tube or rod 19 is compressed and forced into groove 14 past lips 16 and 18, pushing ahead of it a portion of canopy 20. After passing the constriction formed by lips 16 and 18, the tube or rod 19 expands, forcing canopy 20 into engagement with the surface of groove 14 and maintaining that engagement by compressive pressure. While canopy attachment groove 14 is shown in FIG. 2 in its preferred circular or bulbar form, which is most readily fabricated by extrusion, it may be of any other similar cross-sectional form in which a portion of the interior width is greater than the minimum width of the opening through the surface of outer wall 8. Similarly, although it is preferred that both lips 16 and 18 exist, the particular shape of canopy attachment groove 14 may be such that a true lip exists only on one edge of the groove opening.
The collection surface 6 has formed therein a longitudinal groove 22 for condensate collection. Collection surface 6 is shown in the Figures as a sloping surface forming the inner wall of the generally triangular device 2. Where the device 2 has another cross-section. collection surface 6 will of course have a different configuration. For instance, if the cross-section is generally square, the collection surface 6 will be the top surface of the device. In any event, collection surface 6 will have a shape which will direct condensate running down the inside of wall or canopy 20 into condensate collection groove 22. In the generally triangular preferred configuration, the slope of portion 24 of collection surface 6 provides such direction. In addition, the angle at corner 26 will be a fairly large obtuse angle so that the condensate will flow around corner 26 rather than collecting at the corner to form droplets.
Condensate collection groove 22 must be of sufficient depth to collect the condensate as it runs in thereto. Therefore, in the preferred generally triangular configuration the shape of groove 22 will be such as to form a lip 28 which has a damming or containment function.
The condensate collection groove 22 also has a low point 30 from which the condensate is removed. This removal is effected by conduit means 32 which comprises one or more holes providing direct communication between low point 30 of groove 22 and axial opening 10. Condensate thus collecting at low point 30 in groove 22 passes through conduit means 32 into axial opening 10 and is drawn through the latter to some, sort of reservoir or collection means (not shown). The driving force for such movement of the condensate may be merely gravity, such that the condensate flows out of groove 22 through conduit means 32 and into axial opening 10 merely of its own weight. Alternatively, a pump or other suction creating means (not shown) is attached to axial opening 10 and the pressure differential created thereby is employed to draw the collected condensate out of groove 22 and through conduit means 32. The pump or other suction means also serves to draw the collected condensate through axial opening 10 for collection in the reservoir. The amount of suction which is to be maintained in axial opening 10 will depend on the amount of condensate to be collected and the means for maintenance of inflation of the entire structure. The latter is necessary because groove 22 is in direct communication with the interior of the inflated structure and thus a continual suction in axial opening 10 would ultimately serve to deflate the structure unless suitable means of maintaining the desired degree of inflation are used. Such a balancing of the inflating and deflating forces is well within the ability of those skilled in the art. More preferably, however, the normal inflation pressure of the inflatable structure provides a positive pressure differential which forces the condensate through conduit means 32 to axial opening 10. This positive pressure differential also causes the condensate fluid to flow through the axial opening to the collection reservoir (which is maintained at a pressure below the inflation pressure of the structure.) Thus, no external pumping apparatus is required solely for condensate collection.
If desired, similar conduit means 34 may be formed to provide communication between canopy attachment groove 14 and axial opening 10. This will prevent the entrapment of air in groove 14 when canopy and the pressure fit means (e.g., tube or rod 19) are placed therein. Both conduit means 32 and 34 are most readily formed in the device by drilling. The diameters of the holes may be the same or different and in the case of conduit means 32 will be largely dependent on the amount of condensate to be drawn therethrough.
A typical means of joining adjacent devices of this invention in end-to-end relationship is shown in FIGS. 3 and 4. The ends of each section are machined or otherwise formed into a bell opening to accommodate a connecting sleeve 36. The bell openings 38 and 40 shown in FIG. 4 also contain grooves 42 and 44 respectively each of which accommodates a rubber O-ring 46 and 48 respectively. The O-rings, bell openings and connecting sleeve all cooperate to form a tight joint through which condensate can flow and suction can be maintained. Such joints are conventional in the pipe and conduit art and the details of construction and assembly will be well known to those skilled in that art.
FIG. 6 illustrates a method of sealing the outer edges of joints between adjacent devices to prevent the incursion of dirt, water, etc. A conventional flexible duct tape 50 overlaps with and stretches between two adjacent devices (only one of which is shown in FIG. 6) and conforms to the various contours thereof. The tape may extend completely around the entire device or it may be just over a portion of the joint as shown in FIG. 6.
The base 4 of the device provides means for supporting the device and also, where required, for anchoring the device to underlying support structures. Most commonly, the underlying support structure will be the ground, whether common soil, sand or the like. It is also contemplated, however, that an underlying foundation of concrete, wood or other material may be provided on which the device is to be supported. For instance, the device may be laid on the deck surrounding a swimming pool or on a concrete slab intended for use as the floor of the structure.
Where the device is made of a heavy material (e.g., concrete), it may have sufficient weight to anchor the thin wall structure without any auxiliary attachment to the support structure. This would be especially true where there are few dislodging forces, such as strong winds. However, it is preferred that the device be positively attached to the underlying support structure. This prevents accidental dislodgement and provides a measure of dimensional stability to the structure. FIGS. 8 and 9 illustrate two means of attaching the device to such an underlying support structure. The support structure itself is generally designated 52 and may comprise concrete, wood, earth, sand or the like. The base of the device preferably has formed therein lugs 54 and 56 which cooperate with the anchoring device generally designated 58 to anchor the hold down device 2. In the embodiment illustrated in FIG. 8 the anchoring device 58 consists of a fish plate 60 and a driven stake 62. Alternatively, the stake 62 may be replaced by screw or bolt means 59 as illustrated in FIG. 9 or, in relatively loose packed material such as earth or sand, by
such devices as earth augers. Generally the anchoring device 58 will be placed on the outer side of the holddown device 2 since the dislodging forces such as wind are normally applied to that side. However, it is also contemplated that a second anchoring device could be attached to lug 56, as shown in FIG. 9, to provide additional anchoring force or to resist any dislodging forces which may be applied to the inner wall of the hold down device 2. The exact location of the anchoring devices 58 and their spacing along the length of the holddown device 2 will depend on the strength of the various dislodging forces to be encountered and the type of support structure to which the device is anchored.
FIG. 10 illustrates a particular embodiment in which the hold-down deviceis partially buried in the underlying support structure. In one embodiment, the support structure 52 is concrete and the device is embedded by being cast in place when the concrete is poured. Lugs 54 and 56 provide means for securely locking the device in place in the concrete bed. Alternatively, the
I support structure 52 may be backfilled sand or earth.
In this instance it is of advantage to provide articles 64 and 66 to aid in retaining the device in the packed sand or earth. The articles 64 and 66 are commonly strips of wood, flat stone, sheet metal and the like which engage lugs 54 and 56 respectively and extend for some distance into the bed 52 of earth or sand. These serve to distribute forces which would otherwise be concentrated at device 2 and tend to pull device 2 out of the bed of sand or earth. By distribution of these dislodging forces through the bed 52 by articles 64 and 66, the device is more readily retained in place. This technique is commonly used in placing structures in soil or sand and many types of materials, including many scrap boards, rocks and the like have been commonly and satisfactorily used.
In another embodiment, illustrated in FIG. 11, a projecting anchor 68 is used to anchor the device to the bed of earth or other support structure 52. In this embodiment the generally triangular device 2 rests on its base 4 on the top of support structure 52 (represented by dashed lines). The anchor 68, which consists of a web 70 and a footing 72 is buried or embedded in the support structure 52. In FIG. I l the anchor 68 is shown as integral with and extending longitudinally of device 2. However, there may be a series of such anchors 68 each removably connected to device 2 at spaced intervals longitudinally of such device.
The hold-down device of this invention may be fabricated in a number of'ways. It may be, for instance, machined out of suitable 'rod or bar stock. Because of its elongated nature and the longitudinal structure of the grooves, the device is particularly suited to be formed largely by extrusion. Such extrusion will readily form the entire crosssectional shape and elongated shape of the device, leaving only the conduit means 32 and 34 to be formed by subsequent drilling.
The device may be formed of any convenient material which can be machined or, preferably, extruded. Thus, many types of metals, concrete, plastic and the like are entirely suitable. The particular material chosen will depend largely on the size of the device, the desired length of sections, cost factors, material availability, the environment into which it is to be placed and the anchoring scheme contemplated. One preferred material is the asbestos fiber/hydraulic cement composition specifically formulated for extrusion which is described in U.S. Pat. No. 3,219,467 to Redican et al. In another preferred embodiment, the device is made from an extrudable plastic such as polypropylene, polyethylene or similar thermoplastic or thermosetting material.
As an example of the device forming the core of the apparatus of this invention, it is contemplated that the device may be extruded out of the asbestos-cement composition described by Redican et al with the following approximate dimensions:
overall height: 3.8 inches overall width: 4.1 inches axial opening: 1.4 inches diameter cross-sectional shape: isosceles triangle canopy attachment groove:
opening width: 0.16 inches maximum width: 0.29 inches cross-sectional shape bulbar condensate collection groove:
width: 0.25 inches depth: 0.375 inches average configuration: U-shaped, with centerline parallel to outer wall of device and extending from center of axial opening.
width: 0.8 inches height: 0.44 inches What is claimed is:
1. Apparatus comprising a hold-down device for anchoring a side of a thin-walled inflatable structure which encloses a high humidity environment and for simultaneously collecting condensation which is deposited on the interior of the wall of said structure, which comprises:
a. an elongated hollow member having an axial opening therethrough for removal of the collected condensate from said apparatus, a base portion, an outer wall, and a collection surface;
b. said outer wall having therein canopy attachment means;
c. said collection surface having therein a longitudinally extending condensate collection groove; and
d. means providing communication between said condensate collection groove and said axial opening.
2. The apparatus of claim 1 wherein said device has a generally triangular cross-section.
3. The apparatus of claim 1 wherein said canopy attachment means comprises a longitudinally extending groove formed in said outer wall, said groove having a maximum cross-sectional width greater than the width of the opening of said groove in the surface of said outer wall.
4. The apparatus of claim 1 further comprising means for attaching said hold-down device to an underlying support structure.
5. The apparatus of claim 4 wherein said means for attaching comprises at least one lug structure in the base portion of said device.
6. The apparatus of claim 1 further comprising means forjoining a plurality of said devices in adjacent end-toend relationship and for providing a fluid communication passage between the respective axial openings of adjacent devices.
7. The apparatus of claim 1 further comprising means cooperating with said canopy attachment groove to attach said side of said structure to said device.
8. The apparatus of claim 7 wherein said means cooperating engages said side and attaches said side to said device by a pressure fit.
9. The apparatus of claim 1 further comprising means providing communication between said canopy attachment groove and said axial opening. 1
l0. Theapparatus of claim 1 wherein there exists a pressure differential between said condensate collection groove and said axial opening sufficient to cause condensate collected in said groove to flow through said means providing communication to said axial opening.
11. The apparatus of claim 1 wherein said device is composed of a composition comprising asbestos fiber and hydraulic cement.
12. The apparatus of claim 1 wherein said device is composed of thermosetting or thermoplastic extrudable plastic material.