Multiple layer insulation cover

A multiple layer insulation cover for preventing heat loss in, for example, a greenhouse, is disclosed. The cover is comprised of spaced layers of thin foil covered fabric separated from each other by air spaces. The spacing is accomplished by the inflation of spaced air bladders which are integrally formed in the cover and to which the layers of the cover are secured. The bladders are inflated after the cover has been deployed in its intended use to separate the layers of the foil material. The sizes of the material layers are selected to compensate for sagging across the width of the cover so that the desired spacing is uniformly maintained when the cover has been deployed. The bladders are deflated as the cover is stored thereby expediting the storage process and reducing the amount of storage space required.

FIELD OF THE INVENTION 
The present invention is directed generally to an insulation cover, which 
is deployed and stored as desired. More specifically, the present 
invention is directed to a multiple layer insulation cover for a 
greenhouse. More specifically, the present invention is directed to a four 
layer insulation cover for a greenhouse in which the layers are spaced 
from each other by inflatable air bladders. The spaced layers of material 
in the insulation cover are preferably comprised of a metal foil such as 
aluminum which is secured to a polyester scrim. Spaced air bladders are 
incorporated in the cover and these bladders are inflated once the cover 
has been deployed to space the layers. The cover is stored on a suitably 
driven roll and as the cover is retracted onto the roll, the air bladders 
are deflated. 
In use as a greenhouse insulation cover, the multiple layer cover is stored 
on a roll above the level of the growth in the greenhouse. When the sun 
sets in the evening, or at any other time such as an overcast day, the 
cover is deployed to prevent heat loss through the roof of the greenhouse. 
The air bladders, which are inflated after the cover has been deployed, 
act to separate the layers of the cover, thus created air spaces between 
the layers to form an effective insulation cover which retains heat in the 
greenhouse. 
DESCRIPTION OF THE PRIOR ART 
The rising costs of fuel have created a severe problem for the greenhouse 
industry. The structure of the greenhouse, which allows maximum sunlight 
during the day, also allows a great deal of heat to escape during the 
evening. Approximately 10,000 acres are presently under glass in the 
United States; and as the costs of fuel oil and other sources of energy 
increase rapidly, the greenhouse owner is quickly being pushed to the 
point where he cannot continue in operation. 
The problem of heat loss in greenhouses has been recognized and the use of 
covers for greenhouses is known generally in the prior art. In one form, 
these covers are flexible transparent sheets which are secured to the roof 
of the greenhouse on the exterior thereof and are inflated by suitable 
means to provide an air space between the cover and the roof. Another 
device for cutting down on heat loss during the night is the use of 
insulating panels of materials such as expanded foams or the like. These 
panels are either cut to shape and put up in the evening and taken down in 
the morning or are arranged in a manner similar to venetian blinds so that 
they are opened during the day and closed at night. 
A recent attempt at reducing greenhouse heat loss is shown in U.S. Pat. No. 
4,064,648 to Charles C. Cary. The Cary patent is directed to an insulation 
system for greenhouses and the like and is comprised of a flexible sheet 
of material which is wound around a roll, is deployed at night, and is 
stored during the day. Rolls of this material are placed longitudinally 
along the length of the greenhouse and are unrolled across the greenhouse. 
The edges of the flexible sheet are disposed generally in a channel or box 
at either side and a cogged wheel assembly may be used to deploy the 
sheet. The Cary patent also discloses a system for opening the cover in 
response to snow accumulation on the roof of the greenhouse. 
The use of various heat retaining structures and elements is also known 
generally in conjunction with building windows, swimming pools, and other 
such facilities. These structures are often in the form of solid panels 
which can be moved from a storage location to a use location by some 
suitable means. Alternatively, these structures may be a flexible sheet of 
material which is stretched or otherwise secured across the area to be 
protected. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a multiple layer 
insulation cover. 
Another object of the present invention is to provide a multiple layer 
insulation cover in which the layers are maintained in spaced array by 
inflatable air bladders. 
A further object of the present invention is to provide an insulation cover 
for use in a greenhouse. 
Still another object of the present invention is to provide an insulation 
cover having a positive edge seal between the cover and a support track. 
Yet a further object of the present invention is to provide a cover which 
is effective to reduce heat losses by convection, conduction, and 
radiation. 
As will be set forth in greater detail in a description of a preferred 
embodiment, as set forth hereinafter, the multiple layer insulation cover 
in accordance with the present invention is comprised generally of four 
layers of metal foil secured to polyester scrim. The four layers are 
joined, along their longitudinal sides to inflatable air bladders. As the 
bladders are inflated, the multiple layers are caused to separate thereby 
creating air spaces between each layer. The longitudinal edges of the 
cover terminate in generally T-shaped strips which cooperate with supports 
such as PVC piping or the like having an axially extending slot. The top 
of the T-shaped strip is placed within the support piping with the leg of 
the T extending out through the slot in the pipe. Suitably spaced reels, 
driven by electric motors or the like, are placed at either end of the 
area in which the cover is to be deployed to move the cover between its 
stored and deployed positions. 
In contrast with known greenhouse insulation covers which are in the form 
of solid sheets or panels, the multiple layer insulation cover in 
accordance with the present invention is flexible and can be stored on a 
roll when not in use. This facilitates the deployment of the cover in a 
short period of time with little effort. Furthermore, the stored cover 
takes a minimum amount of space, thus when used in a greenhouse, allowing 
full utilization of the space within the greenhouse. 
As was discussed previously, a flexible greenhouse cover is shown generally 
in U.S. Pat. No. 4,064,648 to Cary. This patent shows a single or double 
layer cover with, in the double layer cover, the two layers being 
separated over their entire areas by air pressure. In contrast, the 
multiple layer insulation cover in accordance with the present invention 
is formed of spaced layers with the spacing being accomplished by 
inflatable air bladders along the edges of the cover. These inflatable 
bladders allow the equal spacing of the four layers. Spacing of more than 
two layers could not be obtained with the Cary device unless the pressures 
between the layers were accurately controlled. By inflating only elongated 
tubes instead of the total area between the cover layers, the size of the 
blowers required can be reduced, thus reducing initial cost and operating 
expense. Additionally, the tubes are more rapidly inflated and deflated to 
facilitate deployment and storage of the cover. 
In the cover set forth in the Cary patent, there are provided a plurality 
of separate covers, each of which extends transversely across the 
greenhouse. Contrastingly, in the multiple layer insulation cover of the 
present invention, the cover extends longitudinally along the length of 
the greenhouse. This type of deployment greatly reduces the length of the 
edges that must be sealed to prevent escape of heated air. Each 
longitudinal edge of the cover of the present invention ends in a T-shaped 
strip which rides in a support such as a hollow tube having an axially 
extending slot. The cooperation between the top of the T-shaped element 
and the hollow support, forms a positive seal which prevents escape of 
heated air. The short transverse ends of the cover can be sealed by any 
suitable means and this is a small area to seal in contrast to the 
longitudinal edges. 
The material used to construct the multiple layer insulation cover in 
accordance with the present invention is preferably a flexible metal foil 
adhered to a polyester scrim. This material is readily available 
commercially, is easy to work with, is durable, and is not expensive. 
Thus, the cover which is produced is also long wearing and durable. Its 
initial cost and upkeep costs are low in comparison to the cost of heating 
fuels so that the costs of installing and operating an assembly using the 
multiple layer insulation cover of the present invention are attractive to 
the owner of a greenhouse or the like. 
Since the materials used in the construction of the cover are durable and 
highly flexible, the cover can be rolled on a storage roller and will 
require little space. Repeated deployment and storage of the multiple 
layer insulation cover, as would be required in day to day usage, will not 
cause the materials to wear out rapidly, thus assuring the owner of the 
facility in which the cover is used of having an effective, durable and 
trouble free cover which is easily and rapidly deployable to prevent heat 
losses and to thereby substantially reduce fuel costs in a greenhouse, 
warehouse, or any similar area having heat loss problems.

DESCRIPTION OF A PREFERRED EMBODIMENT 
Turning initially to FIG. 1, there may be seen generally at 10, a multiple 
layer insulation cover in accordance with the present invention. In the 
preferred embodiment, cover 10 is shown deployed in a conventional 
greenhouse, generally at 12. While the cover 10 will hereinafter be 
discussed and described in conjunction with a greenhouse, it is to be 
understood that the invention is not limited to such use. The multiple 
layer insulation cover in accordance with the present invention can be 
used advantageously in any area where it is desired to reduce heat loss. 
By way of example, the cover could be utilized in a warehouse to 
substantially reduce heat loss through a poorly insulated roof. Similarly, 
in a passive solar house with south facing windows, the cover in 
accordance with the present invention could be used to cover the windows 
when there is no sunlight thereby substantially reducing heat loss. 
Accordingly, while the multiple layer insulation cover will be hereinafter 
described in use in a greenhouse, its uses are not so limited. 
As may be seen in FIG. 1, greenhouse 12 is of conventional construction and 
has a plurality of transparent panels 14 which are supported by spaced 
uprights 16 and roof trusses 18 to form greenhouse structure 12 which has 
spaced longitudinally extending walls 20 and 22 and a peaked roof 24. One 
end wall 26 of greenhouse 12 may be seen at the right of FIG. 1 and it 
will be understood that the greenhouse would be closed with a second end 
wall which, for clarity, is not shown. It will also be understood that 
greenhouse 12 could be shaped generally as a hemicylinder or other known 
shape. Greenhouse 12 is also provided with a plurality of spaced benches 
or supports 28 upon which the plants being grown are placed. 
Multiple layer insulation cover 10 is comprised, as may be seen in FIG. 1, 
of four spaced layers 30, 32, 34, and 36, which extend between the side 
walls 20 and 22 of greenhouse 12 and which terminate in inflatable air 
bladders 38 and 40, which, as will be described in greater detail 
hereinafter serve to separate the layers 30-36 when inflated. The cover 10 
extends longitudinally along the length of the greenhouse 12 and is 
secured to the walls 20 and 22 by support tubes 42 which are connected to 
the spaced uprights 16, as will be described hereinafter. A storage reel 
44 is shown supported at the first end 26 of greenhouse 12 by conventional 
means. Reel 44 extends transversely across the greenhouse side walls 20 
and 22 and is rotatable by a suitable power source such as an electric 
motor 46 which transmits power to reel 44 through a drive belt 48 or the 
like. It will be understood that there is also provided a corresponding 
deployment reel assembly (not shown) which would be placed adjacent a 
second end wall of greenhouse 12 and would be similar in structure and 
operation to reel 44. Actuation of the deployment reel assembly would 
cause cover 10 to be deployed in place, as seen in FIG. 1, while actuation 
of the storage reel assembly 44 would store cover 10, thus permitting 
sunlight to pass through the transparent panels 14 to contact the growing 
plants. 
Turning now to FIG. 2, there may be seen an enlarged view of a portion of 
multiple layer insulation cover 10 in accordance with the present 
invention. As was discussed previously, cover 10 is formed by four layers 
30, 32, 34 and 36 which are spaced by an air bladder 40. As may be seen in 
FIG. 2, top and bottom layers 30 and 36, respectively of cover 10 are 
coextensive with a portion of bladder 40. Upper and lower intermediate 
layers 32 and 34 are secured to the outer periphery of bladder 40 at 
spaced locations by any acceptable means or method such as stitching or an 
adhesive. Bladder 40 is formed of the same material as the four spaced 
layers and may be suitably treated to retain air under pressure or may 
carry an air tight plastic inner liner (not shown). The material used in 
the fabrication of the multiple layer insulation cover 10 is, as was 
discussed previously, an aluminum foil secured to a polyester scrim. A 
suitable material is FOYLON and is available from the Duracote 
Corporation. 
The top and bottom layers 30 and 36 and bladder 40 terminate, at their 
outer edge in a generally T-shaped strip or element 50. Strip 50 includes 
a top piece 52 and a leg 54 which cooperate to form the T. As may be seen 
in FIG. 2, strip 50 is disposed with its top 52 within the support pipe 42 
and with leg 54 passing through an axial slot 56 in pipe or support track 
42. This slot 56 may be angled downwardly with reference to a horizontal 
plane thereby reducing wear on the underside of leg 54 of T-strip 50. In a 
preferred embodiment in which the span between side walls 20 and 22 is 
approximately 24 feet, the slot 56 may be angled downwardly at 
approximately 9.degree.. 
Support 42 is shown in the preferred embodiment as PVC piping and this is 
preferred since it is lightweight, durable, impervious to moisture, and 
the like, easily installed, and not particularly expensive. It will be 
understood that other materials could be used for support 42 if necessary. 
Support 42 is secured to the spaced uprights 16 by any suitable means such 
as brackets 58 which are held in place by screws 60 or the like. 
A cable 64 such as wire rope or the like is secured to a leading edge 
portion 66 of T-strip 50 by a suitable U-shaped connector 68. Cable 64 
runs through the support tube 42 and is secured to the deployment reel 
(not shown). Actuation of the deployment reel causes the cable 64 to pull 
the cover off the storage reel 44. It will be understood that a similar 
cable would be provided in the other support tube secured to the other 
side wall of greenhouse 10 and that additional cables could be secured at 
spaced points across the leading edge of the multiple layer insulation 
cover. It will also be understood that the leading edges of layers 30, 32, 
34, and 36 and of bladders 38 and 40 are all sealed together. 
As the cables 64 are wound on the deployment reel, the multiple layer 
insulation cover 10 is pulled off storage reel 44 and is deployed above 
the growing area of greenhouse 12, as seen in FIG. 1 at a desired height 
sufficient to allow access to the plants or benches 28. The leg portion 54 
of T-strip 50 passes through the slot 56 in the support pipe 42 and the 
top portion 52 of strip 50 seals the slot 56 to form an effective air 
seal. As the cover 10 reaches the deployed portion, an air opening 70 in 
the lower side of bladder 40 is placed over a corresponding outlet 72 in 
an air conduit 74. Correspondingly shaped, magnetized flexible gaskets 76 
and 78 are provided with gasket 76 surrounding air opening 70 in bladder 
40 and with gasket 78 being secured about outlet 72 of air conduit 74. Air 
is provided by a blower or fan (not shown) and is directed up conduit 74 
in the direction indicated by arrow A in FIG. 2. This air flow is 
sufficient to inflate bladder 40 to a shape as shown in FIGS. 1 and 2. It 
will be understood that the bladder along the other longitudinal edge of 
cover 10 is being concurrently inflated to deploy the cover with the four 
layers generally uniformly spaced. 
Once multiple layer insulation cover 10 is deployed and the bladders 38 and 
40 are inflated, there is provided an effective means for retaining heat 
in the greenhouse. The four layers 30, 32, 34, and 36 are assembled in 
cover 10 with the reflective side facing upwardly. The air spaces between 
layers stop conductive heat loss, the air spaces are still so there is 
little convective heat loss and the aluminum foil is a poor emitter of 
heat so there is little radiant heat loss. With the cover 10 deployed, the 
heat remains in the greenhouse. There is little heat loss due to poor 
sealing since the T-strip 50 and support tube 42 form an effective seal. 
As may be seen in FIG. 2, the spaces between the uprights 16, transparent 
panels 14 and support tube 42 can be sealed by suitable strips 80 of 
insulation such as expanded foam which are permanently secured in place. 
Suitable means such as suspended drapes or flaps can be provided along the 
end walls of the greenhouse to prevent escape of heated air around the 
reels. 
In a preferred embodiment, in which the width of the greenhouse is 24 feet, 
the air bladders 38 and 40 are structured to have a circumference of 
approximately 30 inches. Top and bottom layers 30 and 36 are in contact 
with bladder 40 each for approximately 14 inches and the intermediate 
layers 32 and 34 are spaced 2 inches from each other. This results in a 
multiple layer insulation cover in which each layer is spaced 
approximately 2 inches from the next layer. The air supplied to bladders 
38 and 40 is only slightly above atmospheric pressure by approximately 0.6 
inches of water. A small fan capacity is required and a fan which provides 
50 CFM and draws only 50 watts of power will be adequate to inflate a 
bladder in several minutes. Since the layers of cover 10 are very light, 
the force of each layer on the bladder is small and would be in the order 
of 0.089 Lb/in over a 24 foot span with a 12 inch sag at the center of the 
span. By suitable analysis, the length of material to be used to form the 
four layers can be selected prior to assembly so that the spacing will 
remain uniform across the entire span. It will be understood that the use 
of bladders 38 and 40, the air pressure required, and the amount of sag 
across the span can be varied depending on the size of the span. It will 
also be understood that the size of the fans can be varied depending on 
how rapidly it is desired to inflate the bladders. Additionally, plural 
fans can be placed along the length of each bladder. Since these fans draw 
little power, they will be left on when the cover is deployed thereby 
insuring inflation of the bladders and spacing of the layers even if there 
are minor air leaks. 
When the cover 10 is to be stored, the fans are turned off and the storage 
reel 44 is actuated to draw the cover 10 to the right, as seen in FIG. 1. 
The air is forced out of the bladders and the T-strips 50, which are made 
of nylon webbing or other similar material, are sufficiently flexible so 
that the top 52 folds adjacent the leg 54 once the T-strip is pulled out 
of the support 42 adjacent take-up reel 44. The rolling of the cover 10 in 
this fashion reduces wear to a minimum and stores the cover in as little 
space as possible. 
The multiple layer insulation cover in accordance with the present 
invention as set forth hereinabove is an effective, economical, and 
dependable way of greatly reducing heat loss through the roof of a 
greenhouse or through any other poorly insulated area. The multiple layers 
of the cover provide good insulation capabilities without bulk and with 
little storage space requirement. The longitudinally extending air 
bladders facilitate the spacing of the layers in an effective and 
economical manner while not requiring large capacity fans or blowers. 
While a preferred embodiment of a multiple layer insulation cover in 
accordance with the present invention has been set forth hereinabove, 
fully and completely, it will be obvious to one of ordinary skill in the 
art that a number of changes in, for example, the number of layers, the 
type of fabric, the drive means for the reels, the shape of the support 
tubes, and the like, could be made without departing from the true spirit 
and scope of the invention and that the invention is to be limited only by 
the following claims: