Note: Descriptions are shown in the official language in which they were submitted.
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FIELD OF THE INVENTION
The present invention related to a window construction having
a continuous reflective sheet extendable in a plurality of
spaced apart layers between the glazings for thermal insula-
tion and privacy.
PRIOR ACT
Multiple glazings are used in windows for reducing heat losses
by creating still air spaces; however radiation losses are still
high due to the high absorbance and emissivity coefficients of
glass to infrared radiation. It is known that shades with a
plurality of spaced apart reflective layers are very effective
because they create insulating still air spaces separated by low
emissivity layers. Such an apparatus is disclosed in Canadian
Patent No. 1,120,784 wherein a shade is made from a plurality
of reflective sheets which are simultaneously unrolled from a
storage roller and drawn across the area of the window while
being kept spaced apart by spacer bars, rollers or strips.
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SUMMARY OF THE INVENTION
It is the purpose of this invention to devise a window
construction having a simpler apparatus for achieving the
above objective by using not a plurality of sheets drawn
simultaneously but a single continuous reflective sheet
extended in a plurality of spaced apart layers. This is
done by having a continuous flexible reflective sheet which
is stored on a storage roller hidden in the upper member of
the window frame during daytime having its free end fastened
to the upper member, extended downward and kept spaced apart
by a vertically free moving spacer weight roller when the
sheet is unrolled from the storage roller.
For extending the sheet in a two-layer configuration a single
spacer weight roller extends the sheet downward by gravity as
the storage roller is rotated to unwind the sheet.
For extending the sheet in a 4-layer or more configuration free
rotating stationary rollers mounted along the upper window frame
member alternate with spacer weight rollers. As the sheet is
unwound from the storage roller, the stationary spacer rollers
and the spacer weight rollers combine their action for extending
the sheet in a plurality of spaced apart layers.
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The portion of sheet thus extended in spaced apart layers
define enclosed air spaces of thickness generally equal to the
diameter of the rollers. The thickness of these air spaces
is preferably close to the optimum thickness for the maximum
air insulation resistance having the minimum natural convection.
The sheet being reflective the multiple layers eliminate losses
through radiation and provide privacy as a side benefit.
DESCRIPTION OF THE DRAWINGS
. .
Figure 1 is a vertical cross-sectional view of the window
construction showing the sheet extended in a two-layer confi-
guration creating three air spaces in the insulating mode.
Figure 2 is a vertical cross-sectional view of the window cons-
truction showing the sheet extended in a larger number of layers
creating a larger number of air spaces in the insulating mode.
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Referring now to Figure 1, in a window construction having a
transparent area defined by glazings 18, a continuous flexlble
reflective sheet 2 of width equal to the horizontal width of
the transparent area of the window and of length a plurality
of times the vertical length of the transparent area of the
window, has one end edge attached squarely to storage roller 4
mounted between glazings 18 adjacent to top member 11 of the
window frame perpendicularly to the vertical side member 13
of the window frame and in a pla~e generally parallel to
glazings 18, the other end edge of the sheet being attached
squarely to the top member 11 of the window frame between the
glazings 18 by fastening bar 6 which is parallel to storage roller
4 and spaced away from the vertical unrolling plane of the sheet
from storage roller 4 a distance approximately equal to the
diameter of spacer weight roller 8.
Spacer weight roller 8 is vertically free moving and suspended on
sheet 2 intermediate storage roller 4 and fastening bar 6, being
at dotted position 9 when sheet 2 is fully wound up on storage 4
in the light transmitting mode. As sheet 2 is unrolled from sto-
rage roller 4, it is pulled downward and tensioned by spacer weight
roller 8 in two spaced apart portions of sheet cooperating with
glazings 18 to define three air spaces 16 in the insulating mode.
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Flexible seals 12 attached inside the vertical side members 13
of the window frame and parallel to the vertical side edges of
sheet 2 seal the gap between the vertical edges of sheet 2 and
the vertical side members 1~ of the window frame and seals 14
seal the bottom edge of sheet 2 against the bottom member 15
of the window frame in order to reduce convection air flow
between the enclosed spa~ces 16. Seals 12 also serve to guide
spacer weight roller 8 vertically.
Figure 2 shows how the addition of stationary spacer rollers 22
mounted along the top window frame member intermediate the sto-
rage roller 4 and the fastening bar 6, plus additional spacer
weight rollers 8 can increase the number of reflective layers
and enclosed air spaces for increased thermal insulation.
Storage roller 4 may be reversibly rotated manually by such
means as illustrated by hand crank 24 or through a cord driven
pulley (not shown) at the end of storage roller 4, or it may be
rotated by a reversible electrical or air motor in which case limit
switch 20 (Fig. 1) stops the motor when contacted by storage roller
8 when sheet 2 is fully extended.
The window construction may be of a standard double glazed unsealed
openable sliding type or of a double glazed sealed type, the reflec-
tive sheet being extendable between the two glazings. In the latter
case, driving the storage roller inside the double glazing requires
effectively sealing the driving mechanism with means such as seals
26 in Fig. 2 or the use of a magnetic coupling to preserve the
sealed characteristics of the window as illustrated in Fig. 3,
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where a reversible motor 28 rotates a first magnet 30 which
drives a second permanent magnet 34 inside the sealed window
(a portion of which is only shown) through sealing membrane
32 made of a magnetically permeable material such as aluminum
or plastics.
Altough arrangements have been shown wherein the insulating
sheet 2 is mounted between a pair of glazings as in a double
glazed window, it is readily appreciated that the insulating
sheet 2 may be also mounted on the room side of a window as
illustrated in Fig. 2 by removing the inner glazing as shown
by dotted line 19.
In the preferred embodiments of the invention at least one and
preferably both side of the sheet are highly reflective to in-
frared radiation, having low absorbance and emittance coefficients.
Aluminized polyethylene teraphthalate film is most suitable.
While only certain embodiments of the invention have been des-
cribed it is apparent that modification may be made without
departing from the true scope and spirit thereof as defined in
the appended claims.
