Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02324318 2000-10-25
TITLE
FOAM INSULATION AND SHADING SYSTEM
FIELD OF THE INVENTION
This invention relates to a replaceable foam insulation and shading system for
a
building structure.
BACKGROUND OF THE INVENTION
Many buildings and structures have large areas of transparent material in
their
exterior shells to permit solar heat gain so as to reduce heating costs and to
permit the
entry of light into their interiors during the day. Greenhouses are an example
of such
buildings. Greenhouses typically rely on the sun to provide both heat and
light to their
interiors.
Greenhouses often have transparent roofs and walls so as to utilize as much
sunlight as possible. One problem with such structures is that it is difficult
to control the
heat loss and gain through the transparent roofs and walls. Typically,
greenhouse heat
loss has been dealt with by heating greenhouses with expensive electric or
petroleum fuel
heaters. Such heaters tend to dry the air they are heating. Most plants grow
better in
humid rather than dry air. Drying the air in a greenhouse tends to slow plant
growth.
In the past, the operators of greenhouses which were getting too hot would
simply
open a vent or door in the greenhouse to permit cooler air into the
greenhouse. However,
the air inside many greenhouses now has extra carbon dioxide added to it to
promote
photosynthesis in the plants. The carbon dioxide is wasted when the interior
of the
greenhouse is cooled by exchanging this carbon dioxide rich air for the normal
outside
air. As well, the air outside the greenhouse is often drier than the air
inside the
greenhouse. Further, permitting fresh air into a greenhouse typically also
permits the
entry of insect pests and undesirable windborne seeds.
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One way to overcome the heat loss problem is to have a double glazing with a
cavity between two glass sheets or other transparent sheet materials. This
increases the
insulating value of the shell of the greenhouse to some degree, but it does
not aid in
controlling the entry of solar radiation. It has been suggested that the
cavities between the
double panes in a wall or roof be filled with foam when it is desirable to
reduce the heat
passing through the wall or roof.
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BRIEF SUMMARY OF THE INVENTION
The present invention is an integrated greenhouse wall and roof foam
insulation
system. The foam insulation system includes an improved means of generating
foam.
The foam insulation system includes a means of controlling the distribution of
the foam
so as to optimize the entry of light, and the loss or gain of heat, whichever
is desired.
The foam insulation system includes a foaming liquid circulation system and an
air circulation system.
Foam insulation reduces the amount of heat radiated through the roofs and
walls
of a greenhouse. As well, the foam bubbles trap the air in the cavity, thereby
reducing the
connective currents in the cavity.
Heating the foam aids in warming the interior of the greenhouse without the
necessity of drying the air inside the greenhouse. The warm foam is in contact
with, and
conducts heat to, the inner skin of the roof and walls. The inner skin
conducts this heat to
the air inside the greenhouse which contacts the inner skin as it circulates
within the
greenhouse. Chilling the foam aids in cooling the interior of the greenhouse
without the
necessity of drying the air inside the greenhouse. The chilled foam is in
contact with, and
conducts heat away from, the inner skin of the roof and walls. The foam may be
heated
or chilled by: heating or chilling the foaming liquid; heating or chilling the
air with which
the foaming liquid is mixed; or both
The various features of novelty which characterize the invention are pointed
out
with more particularity in the claims annexed to and forming a part of this
disclosure. For
a better understanding of the invention, its operating advantages and specific
objects
attained by its use, reference should be made to the accompanying drawings and
descriptive matter in which there are illustrated and described preferred
embodiments of
the invention.
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IN TIDE DRAWINGS
Figure 1 is a schematic representation of the foam insulation and shading
system;
Figure 2 is a sectional view of a foamer;
Figure 3 is a sectional view of a foamer, of the type depicted in Figure 3,
with the view
from the end of the foamer rather than the side as in Figure 3;
Figure 4 is a sectional view of a bubble tube having orifices in its bottom
surface;
Figure 5 is a sectional view of a bubble tube having an opening in its bottom
surface
containing a porous sponge;
Figure 6 is a sectional view of an inner tube/outer tube combination having
orifices in its
bottom surface wherein the inner tube may be rotated relative to the outer
tube;
Figure 7 is a sectional view of an inner tube/outer tube combination having an
opening in
its bottom surface containing a porous sponge wherein the inner tube may be
rotated
relative to the outer tube;
Figure 8 is a sectional view of a foamer;
Figure 9 is a sectional view of a foamer, of the type depicted in Figure 8,
with the view
from the end of the foamer rather than the side as in Figure 8;
Figure 10 is a sectional view of a portion of the roof of a greenhouse
structure showing an
integral trough containing a foamer; and
Figure 11 is a sectional view of a portion of the roof and wall of a
greenhouse showing a
gutter containing a foamer.
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DESCRIPTION OF A SPECIFIC EMBODIMENT
Refernng to Figure 1, the invention is illustrated by way of a simplified
schematic
drawing of a greenhouse structure (10) showing the major components of the
foam
insulation and shading system ( 12), including the reservoir ( 14); air mover
( 16) and the
foamer (18).
The wall and roof of the greenhouse structure (10) each have an inner skin
(20)
and an outer skin (22) with a void between the inner skin (20) and the outer
skin (22). In
Figure 1, this void is divided into compartments, being two roof compartments
(24) and
two wall compartments (26). For simplicity, in Figure 1 the foam insulation
and shading
system (12) is shown as only involving the left roof compartment (24), but in
normal use
the foam insulation and shading system would typically involve all of the roof
compartments (24) and the wall compartments (26).
The reservoir (14) contains a foaming liquid (28), such as are well known to
those
skilled in the art. A chiller (30) is connected to the reservoir (14) by
suitable conduit so
that the foaming liquid (28) may be cooled by the chiller (30). A heater (32)
is connected
to the reservoir (14) by suitable conduit so that the foaming liquid (28) may
be heated by
the heater (32). It will be apparent to those skilled in the art that there
are many different
ways to heat or cool the foaming liquid (28) in the reservoir (14).
The reservoir (14) is connected to the roof compartment (24) by the return
pipe
(34). The reservoir (14) is connected to the pump (36) by the pump intake pipe
(38). The
pump (36) is connected to the foamer (18) by the fill pipe (40). Typically,
the return pipe
(34), pump intake pipe (38) and the fill pipe (40) comprise commercially
available pipe
such as plastic pipe. In use, the pump (36) pumps the foaming liquid (28) to
the foamer
(18). It will be apparent to those skilled in the art that the pump (36) could
be in various
configurations, including a sump type pump installed within the reservoir (
14).
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The air mover (16) may be any suitable means of supplying air, such as a
compressor or a simple blower, both of which are well known to those skilled
in the art.
The air mover (16) is connected to the foamer (18) by a suitable conduit, such
as an air
pipe (42) (shown in Figures 8 and 9) or an air duct (44) (shown in Figures 2
and 3),
depending on the pressure and volume of the air required for the particular
foamer (18).
In some applications, it is beneficial to be able to cool or heat the air
supplied to the
foamer (18) from the air mover (16). It will be apparent to those skilled in
the art that
there are many effective means for heating or cooling the air.
The foamer (18) is a device which enables the air provided by the air mover
(16)
to blow through the foaming liquid (28) so as to form bubbles (46) in a
particular
compartment. The insulation and shade provided by the bubbles (46), and the
durability
of the bubbles (46), depends on the size of the bubbles (46). As a general
rule, larger
bubbles (46) provide less shade and more insulation than smaller bubbles(46),
but larger
bubbles (46) tend to dissipate sooner than smaller bubbles (46). Therefore,
the optimum
bubble size depends on a variety of factors including the outside temperature
and the
amount of sunlight. It is desirable to be able to vary the bubble (46) size in
response to
changing conditions. As well, it is desirable that the bubbles (46) be of
uniform size so
that they uniformly provide the optimum amount of shade and insulation.
In the present invention, the foamer (18) preferably spans the relevant roof
compartment (24) or wall compartment (26) so as to generate bubbles (46) along
the
length of the compartment, often along the bottom or lower side of the
compartment.
Therefore, the foamers (18) tend to be long. Typically, it is preferable that
the bubbles
(46) be of a fairly uniform size so that a particular batch of foam has
uniform shading and
insulating qualities. Creating uniform bubbles (46) along the length of the
foamer (18)
requires that uniform amounts of air are blown through the foaming liquid (28)
along the
length of the foamer (18).
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In use, the foaming liquid (28) in the reservoir (14) may be heated or chilled
as
desired. The pump (36) draws foaming liquid (28) from the reservoir (14) and
pumps it
to the foamer (18). The air mover (16) draws in air and supplies it to the
foamer (18).
The air may be heated or cooled if required. The air and the foaming liquid
(28) mix at
the foamer (18), forming bubbles which fill the roof compartment (24). The air
in the
roof compartment (24) which is displaced by the bubbles (46) escapes through
the
compartment vent (47). The compartment vent (47) preferably comprises a screen
(not
shown) through which the air passes. The screen acts to pop any bubbles (46)
contacting
it so as to prevent the foaming liquid (46) from escaping. Over time, the
bubbles (46) in
the roof compartment (24) begin to pop. The foaming liquid (28) from the
popped
bubbles (46) flows either directly back into the foamer (18); or to the bottom
of the roof
compartment (24), down the return pipe (34) and into the reservoir (14) from
which it can
be pumped to the foamer (18) as needed.
One embodiment of the foamer (18) is shown in Figures 2 and 3. An air duct
(44)
is connected to the air mover (16) (not shown). A series of bubble tubes (48)
are
connected to the air duct (16) at each end of the bubble tubes (48). The
bubble tubes (48)
are at least partially immersed in the foaming liquid (28). The foaming liquid
(28) is
contained by the sidewalls (50) of the foamer (18). Alternatively, the foaming
liquid
could be contained by a feature of the greenhouse structure (10) as shown in
Figures 10
and 11. In the embodiment shown in Figures 2 and 3, the bottom surface of the
bubble
tubes (48) contains orifices (52) to permit air to blow into the foaming
liquid (28). As set
out below, other embodiments of the bubble tubes (48) may be used. The bubble
tubes
(48) contain check valves (54) which open when air is blown into the bubble
tubes (48)
from the air duct (44) and close when air is not being blown into the bubble
tubes (48) so
as to prevent the foaming liquid (28) from flowing into the air duct (44). The
large
volume of the air duct (44) relative to the volume of the bubble tubes (48);
the relatively
short length of the bubble tubes (48); and the fact that the bubble tubes (48)
are connected
to the air duct (44) at both ends, operate to ensure that substantially the
same amount of
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air will pass through each orifice (52), thus producing uniform bubbles (46).
As shown in
Figure 3, bubble tubes (48) may be positioned side by side above the air duct
(44).
Figures 4, 5, 6 and 7 are sectional views illustrating different embodiments
of the
bubble tubes (48). In all of these embodiments, in use the bubble tube (48) is
at least
partially immersed in the foaming liquid (28). Figure 4 shows a bubble tube
(48) having
three rows of orifices (52). Figure S shows a bubble tube (48) having an
opening (56)
filled with a porous sponge (58). In use, the air supplied by the air mover
(16) blows
through the porous sponge (58) into the foaming liquid (28).
With the embodiments of the bubble tube (48) shown in Figures 4 and 5, the
size
of the bubbles (46) may be altered by changing the pressure of the air
supplied by the air
mover (16) which will alter the volume of air flowing through the bubble tubes
(48).
With the embodiments of the bubble tube (48) shown in Figures 6 and 7, the
volume of
air flowing through the bubble tubes (48) may be altered by altering the size
of the holes
in the bottom of the bubble tubes (48). The embodiments of the bubble tubes
(48) shown
in Figures 6 and 7 comprise an inner tube (60) and an outer tube (62)
configured such that
the inner tube (58) can rotate relative to the outer tube (60). In the
embodiment shown in
Figure 6 the inner tube (60) and the outer tube (62) have matching orifices
(52) and the
amount of air flowing through the orifices (52) can be controlled by rotating
the inner
tube (60) relative to the outer tube (62) so as to constrict or dilate the
orifices (52). In the
embodiment shown in Figure 7, the inner tube (60) and the outer tube (62) form
a
common opening (56) containing a porous sponge (58). The amount of air flowing
through the porous sponge (58) can be controlled by rotating the inner tube
(60) relative
to the outer tube (62) so as to constrict or dilate the opening (56). It will
be obvious to
those skilled in the art that there are many means actuating the rotating of
the inner tube
(60) relative to the outer tube (62).
Figures 8 and 9 show another foamer (18) embodiment comprising an air pipe
(42) connected to the air mover (16) (not shown) and a feeder pipe (64). The
feeder pipe
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(64) is~connected to a bubble tube (48) at a plurality of locations along the
length of the
feeder pipe (64) and the bubble tube (48). In Figures 8 and 9, the foamer (18)
is shown
having orifices (52) along the bottom. The foamer (18) may be configured in
any of the
ways described in this specification. The diameter of the air pipe (42) and
the feeder pipe
(64) is larger than the diameter of the bubble tube (48), which acts to ensure
that the
pressure within the bubble tube (48) is substantially uniform and that
therefore the air
passing out of the bubble tube (48) is substantially uniform along its length.
As shown in Figures 10 and 11, foamers (18) may incorporate declivities which
are integral to the relevant structure for the purpose of containing the
foaming liquid (28).
Figure 10 shows a portion of a roof of a type of greenhouse having an internal
trough
(66). The trough (66) contains foaming liquid (28) and a bubble tube (48) so
as to permit
bubbles (46) to be formed in the trough (66). Trough vents (68) permit bubbles
(46) to
flow into the adjoining roof compartments (24). Figure 11 shows a gutter (70)
formed at
the meeting of a wall and the roof of a structure with an inner skin (20) and
an outer skin
(22). The gutter (70) contains foaming liquid (28) and a bubble tube (48) so
as to permit
bubbles (46) to be formed in the gutter (70) and to fill the roof compartment
(24).
Analogous declivities are typically present at the bottom of the wall
compartments (26).
The foregoing is a description of a preferred embodiment of the invention
which
is given here by way of example. The invention is not to be taken as limited
to any of the
specific features as described, but comprehends all such variations thereof as
come within
the scope of the appended claims.
