Lightweight construction element

A lightweight construction element is provided with a fabric backing from untrimmed velvet fabric, coated to render it airtight and pressure resistant, with the internal space thereof allowing pressurization. With the pressurizing medium filled in, the yarn linking the two outer fabric webs will maintain a predetermined distance between the fabric webs and ensure high stability of the element.

BACKGROUND OF THE INVENTION 
The present invention relates to a lightweight construction element, 
comprising a fabric backing, coated to render it airtight and pressure 
resistent. 
DESCRIPTION OF THE PRIOR ART 
In a known lightweight construction element of this category, the fabric 
backing is fabricated from a flexible foil of composite material, provided 
with a textile web produced from synthetic yarn and coated on both sides 
with plastic. Two sections of plastic foil, cut to size and fixedly joined 
to each other by sealing or bonding their edges, are filled with a 
semi-rigid or still elastically deformable plastic foam, which structure 
is produced by pouring plastic material directly into the cavity. 
This lightweight construction element is of the disadvantage that its 
production requires metallic molds for absorbing the high pressures 
prevailing when pouring the plastic foam material. The shape of the 
lightweight construction element, once it has been completed, cannot be 
altered any more and it is also not possible to fold it into a small 
volume for purposes of transportation. 
Another known lightweight construction element is assembled from two 
identical sections. Each section has a fabric substrate onto which a 
number of parallel ribs formed from polyurethane foam with triangular, 
rectangular or trapezoidal cross-section are fixed by means of a textile 
web. Between the individual ribs, the fabric web is joined to the fabric 
substrate by seams. Both sections are laid one upon the other, so that 
their ribs will mesh like gear teeth. The lightweight construction element 
is provided with two covering layers of fabric and impregnated with a 
liquid plastic to which a catalyst for curing of the plastic is added. 
But this lightweight construction element can likewise not be folded when 
not in use. 
Furthermore a lightweight construction element is known, which is provided 
with glass-fiber reinforced polyester panels, wherein the space enclosed 
by the polyester panels contains a frame structure in the form of coils 
from metal wire or from glass-fiber reinforced polyester, or in the form 
of a mesh constructed from such coils. The individual coils are imbedded 
in a fabric layer impregnated with polyester. Although this construction 
will increase the load-bearing capacity of the lightweight construction 
element, it is also not possible therein, to fold the element when not in 
use or when it is to be transported. 
Finally, it has also been proposed to use air-filled cushion-type elements 
for different technical applications. Such cushion-type elements are 
fabricated from a foil-type material, with the foil edges joined by 
sewing, bonding or sealing. 
Although such cushion-type elements generally allow folding into a small 
volume when not in use, their disadvantage is that certain limits are set 
for their shape, as their shape will depend upon the pressure of the air 
or other medium used for inflation, and they can therefore not be designed 
as, respectively, a panel-shaped or casing-shaped lightweight construction 
element with exactly prescribed dimensions since the pressure of the 
filled-in pressurizing medium will force areas of larger dimensions to 
bulge outwards. 
SUMMARY OF THE INVENTION 
The present invention has as an object to eliminate the aforenamed 
disadvantages of known designs and to create a lightweight construction 
element of the initially outlined type, having dimensional stability 
despite its low weight, also being of simple construction and inexpensive 
to fabricate, and for which no costly metallic molds should be required. 
The surfaces of the lightweight construction element should, furthermore, 
not bulge outward upon pressurization of the internal space thereof. 
According to this invention, this is attained by a fabric backing 
consisting of an untrimmed velvet fabric, with the airtight coating 
allowing to pressurization of the internal space of the velvet fabric. The 
vertical pile yarn linking the two velvet fabric webs will hold these two 
webs at a predetermined distance when the internal space of the velvet 
fabric is filled with a pressurizing medium. These vertical pile yarns 
will reliably prevent bulging out of the fabric webs during the filling 
process and after its conclusion. High stability of the filled lightweight 
construction element will concomitantly be ensured thereby. 
When using a gaseous or liquid medium as a pressurizing agent, it will be 
practicable to relieve the pressure in the internal space of the 
lightweight construction element when the element is not to be used any 
longer, and then to fold up the element. It will thus be possible to save 
space in storage and transportatation. Installing and removing the element 
is extremely simple and may be made by unskilled personnel without 
requiring any special training. 
Should it be intended however, to use the lightweight construction element 
only once, it will be practicable as per a further modification of the 
invention, to use a hardenable plastic foam as a pressurizing medium. This 
foam will ensure adequate dimensional stability of the lightweight 
construction element, and also ensure a relatively low weight. 
The invention furthermore provides in another embodiment for a minimum of 
one feeder pipe to project into the internal space of the lightweight 
construction element. This will ensure a supply and uniform distribution 
of any pressurizing medium. It is practicable to use the feeder pipes for 
arranging a plurality of lightweight construction elements in succession, 
and to supply these from a single source for the pressurizing medium. 
The lightweight construction element as per the present invention may be 
used with advantage in various fields. It can be utilized in the 
construction of self-supporting sheds, of tents, movable partition walls 
of any kind, of casings, jackets for containers, circular silos, formwork 
elements for the construction industry, etc. Also coming into 
consideration is use of the element as packing material, particularly 
since this affords the possibility of saving costs by returning empties in 
a folded-up state.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The lightweight construction element shown in FIG. 1 comprises an a first 
or upper fabric web 1 and a second or lower fabric web 2, with the fabric 
webs pressure-resistant coated on their outer sides and linked to each 
other in the manner of an untrimmed velvet fabric by vertical pile yarns 
3. The number of yarns 3 amounts to approximately 30 to 200 per cm.sup.2. 
The distance 5 of upper fabric web 1 from lower fabric web 2 may 
preferably be between 2 and 20 mm. 
In FIG. 2 as well both fabric webs are provided with a coating 6 
impermeable to air. Such coating, in general a rubber coating applied by 
vulcanizing, may be made impact resistant, slip-proof, smooth, rough, 
resistant to cold or heat, resistant to chemicals, insulting, etc., as may 
be required. The fabric webs of the lightweight construction element are 
joined together at both sides by seams 4. Since the coating 6 is 
impermeable to air, the internal space or chamber 7 of the lightweight 
construction element may be pressurized and the element thus be made into 
a stable structure. Suitable as pressurizing media will be primarily gases 
such as air, helium, etc., or liquids. It is, however, also practicable to 
fill the internal space 7 with a foamed material, for instance 
polyurethane foam, which after pouring will harden. 
According to FIG. 3 the two lightweight construction elements 10 and 11 are 
joined by a layer 9 of a bonding agent. Seams may, however, also be used 
instead of this bonding layer 9. To allow simultaneous pressurizing of the 
internal spaces of both elements 10 and 11, their internal spaces are in 
communication by means of a pipe 12, which is bent to an angle. A straight 
pipe 12' serves to introduce the pressurizing medium or foam material into 
the internal space of element 11. 
The shed shown in FIG. 4, constructed from a construction element as per 
the invention, is of semicircular cross section with flanges 14 attached 
to the ends of the arched element and resting upon the base 13. Both 
flanges 14 are provided at their upper sides with hold-down rails 16 which 
are fixed to base 13 by means of bolts 17. In this instance, too, a 
pressurizing medium is supplied to the internal space of the element 
through piping provided with a manually operable valve 8. This valve 8 is 
connectable through a supply line 18 to a pressurizing-medium source, for 
instance a pump or a compressed-air cylinder. Furthermore, the 
pressurizing medium contained in the lightweight construction element may 
be vented to the atmosphere by means of valve 8. The shed as shown may be 
open at its front end since no air lock is required herein as would be the 
case with air-supported tents. 
The present invention is not limited in any way to the embodiments shown in 
the drawings and described in the aforegoing. It would, for instance, also 
be practicable to apply to both fabric webs of the lightweight 
construction element a flexible plastic coating instead of a rubber 
coating.