Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to insulated multi-pane glazed units.
Such units are used for residential and commercial construc-
tion where controlled light transmittance and low sound and heat
transmittance is desirable.
2. Description of the Prior Art
Units of this type and their properties are described in the
Canadian Building Digest, put out by the Division of Building Research,
National Research Council of Canada, October 1963, in an article
"Factory Sealed Double-Glazed Units" by Solvason and Wilson.
The structure described in this article is a typical insula-
ting glass unit having two panes spaced-apart by a hollow metal spacer
containing a desiccant and surrounded by one or two sealants between
the frame and pane.
The prior art structure has a number of disadvantages. For
example, the joint design predisposes the units to breakage because,
as the glass moves due to barometric pressure and temperature changes,
the spacer acts as a fulcrum point introducing stresses to the glass
surface. This problem is discussed in an article in Glass Digest for
February 15, 1982 by A. Risher Hall. The units also require desiccants
which are expensive and also predispose the windows to breakage. The
breakage problem is discussed in Glass Digest for December 15, 1981 by
Richard Solvason, in a paper by C. J. Barry of Ford Glass Limited,
presented to the Insulated Glass Manufacturers Association on June 6,
1985, in an article by Lynn Beason in Glass Digest for February 15,
1986, in an article by J. P. Ausikaitin in Glass Digest for October
15, 1982, and in an article by Helmut Brook in Glass Digest for
June 15, 1986.
Also the seals on the units have short finite life due to
moisture vapor and transmission properties of the organic sealants
used. This problem is discussed in a paper delivered at the Sealed
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Insulated Glass Manufacturers Association, June 1955 by Bachman,
Glass Develop AB, Lund, Sweden and in a paper by Aulis Bertin
delivered to the Insulated Glass Manufacturers Association, General
Meeting, Toronto, January 10-11, 1979.
Conventional units also use hollow metal spacers (containing
desiccants). These spacers are difficult to joint at the corners and
decrease the visual area of the unit. They also provide fulcrum
points giving ruse to the breakage problem described above. The
spacers are usually made of aluminum which has a different coefficient
of thermal expansion to the glass. The high heat conductivity of the
aluminum reduces the thermal value of the unit and places internal
stresses on the pane.
United States Patent 2,589,064, Drake (1952) discloses a
multiple sheet glazing unit having separator means provided with
flanges sitting on the edges of the panes and secured to them by
metallic coatings and solder. Extending from the flanges between
the panes is an undulating or accordian-like spacer. Applicant
introduces this patent as a basis for explaining the distinction
over it of the present invention. A main shortcoming of this
structure is that the spacer cannot readily be brought around the
corners and, therefore, cannot be used in a continuous band.
Similar shortconlings attach to the structures shown in U.S. Patents
4,312,457, Allaire (1982) and 4,393,105, Kreisman (1983).
Reference is also made to the applicant's prior Canadian
Patent Application 432,631, filed July 18, 1983. This application
discloses an assembly comprising two panes of glass of the same
areal dimensions in registering parallel relationship with a plurality
of non-rigid slightly compressed spacer members sandwiched between
them. A cap of impervious material covers and adheres to the peri-
pheral edges of the panes and bridges the gap between them to form a
hermetically sealed chamber. The chamber is under partial vacuum so
that implosive pressure urges the panes and cap together and the panes
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against the spacer members.
It is an aim of the invention to provide an effective
insulated glazing unit using common readily available materials and
technique and which avoids the disadvantages of prior art structures.
SUMMARY OF THE INVENTION
A double glazed unit, according to the invention, is made up
of opposed glass panes connected and held apart by a sealing band of
unique construction, which extends completely around the periphery of
the unit and adheres to the edges of the panes. The sealing band is
made up of a central channel part of overall curved cross section,
located between the inside edges of the panes and an integral flange
at each side of the channel part juxtaposed and secured to the edge
surface of a pane. The channel part is provided with transverse
corrugations which endow the band with strength and flexibility in
all directions.
The invention also contemplates multiple glazing having more
than two panes. In this event, the sealing band may have several
channel parts intervened by an integral connecting web and integral
terminal flanges for connection to the edges of the panes or alterna-
tively may have inset inside panes and a single wide channel partbetween the outside panes.
The invention lends itself to multi-glazed structures with a
simple air space between panes or structures in which the space or
spaces are partially evacuated or gas filled. In the latter event,
special spacing members are provided to maintain a given space between
panes under the external pressure of the atmosphere urging them together.
BRIEF DESCRIPTION OF THE DRAWINGS
Having thus generally described the invention, it will be
referred to in more detail by reference to the accompanying drawings,
which illustrate preferred embodiments, and in which:
FIG. 1 is a fragmentary perspective view of a double glazed
unit, according to the invention;
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FIG. 2 is an enlarged fragmentary perspective view showing
a length of the edge sealing band used in the units
Figs. 1 and 4;
FIG. 3 is a cross-section along the line 3-3 of Fig. 2.
FIG. 4 is a double glazed unit, according to the invention,
which is under partial vacuum;
FIG. 5 is a fragmentary vertical cross-section through an
evacuated triple glazed unit, according to the
invention; and
FIG. 6 is a fragmentary enlarged perspective view showing
a length of sealing band for the triple glazed unit
of Fig. 4.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Fig. 1 shows a typical double glazed insulating unit, accord-
ing to the invention. It is made up of a pair of opposed glass panes
15 and 17, intervened by a space 19. The panes are urged towards
; each other by atmospheric pressure acting on their outside surfaces.
The pane 15 has an inside surface 15a and peripheral edge surfaces 15b.
The pane 17 similarly has an inside surface 17a and edge surfaces 17b.
Preferably, the corners of the panes 15 and 17 are rounded off as shown.
A sealing band B is intimately bonded to the edge surfaces
of the panes and bridges the gap 19 between them.
The sealing band B is an integral elongated thin impervious
specially constructed band of flexible resilient sheet material having
a central channel part 25 of curved cross section. The channel 25 is
provided with a series of regular transverse corrugations, each pre-
senting a series of valleys a and intervening crests b. The channel
25 is flanked at each side by a wide flat integral lip 29.
The sealing band B is applied to the glazing structure with
the lips 29 lying flat on the edge surfaces 15b and 17b of the
respective panes, and intimately bonded thereto to form sealing space
19 between the panes. The band B is dimensioned so that the channel
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25 bridges the space 19 and just fits between the inside surfaces 15a
and 17a, where they merge with the end surfaces 15b and 17b respectively.
Fig. 4 shows a typical double glazed evacuated insulating
unit, according to the invention. Similar reference numerals have
been applied to similar parts as in Fig. 1 but raised by 100. It is
made up of a pair of opposed glass panes 115 and 117, intervened by
partial vacuum space 119. The panes are urged towards each other by
atmospheric pressure acting on the outside.
The pane 115 has an inside surface 115a and peripheral edge
surfaces 115b. The pane 117 similarly has an inside surface 117a and
edge surfaces 117b. Preferably, the corners of the panes 115 and 117
are rounded off, as shown in Fig. 1.
The panes 115 and 117 are held apart by a number of spacers
A1 each made up of a small solid sphere 121, sandwiched between a pair
of pads 123, each bearing against a surface 115a or 117a, as the case
may be, of a pane.
A sealing band B1 is intimately bonded to the edge surfaces
of the panes and bridges the gap between them, as will be clear from
the description of Fig. 1.
Fig 5 shows a triple glazed structure, according to the
invention. It includes spaced-apart glass panes 215, 216 and 217.
The panes 215 and 217 have inside faces 215a and 217a respectively
and peripheral edge faces 215b and 217b. The intermediate pane 216
has opposed faces 216a and 216c and a peripheral edge face 216b which
is inwardly spaced as compared to the edge faces 115b and 117b.
The panes are spaced-apart by spacers A2 in the form of
malleable plastic discs 230 so as to maintain vacuum spaces 219
between the panes 215 and 216, and 220 between the panes 216 and 217.
The discs 230 between the center pane and respective outer panes are
staggered to increase the conductive path through the unit. Where
ball and pad spacers, as described above, are employed, a rigid ball
of steel or ceramic bearing on hard pads preferably of steel or
ceramic may be used. The pads are hard enough to prevent substantial
penetration by the ball. The conductive path is minimized by the
point loading between the ball and pads. The discs 230 are of high
strength plastic material cleaned by plasma discharge to prevent out-
gassing in vacuum. These plastics are slightly malleable to accommo-
date a small amount of movement in the glass without fracturing it.
These plastics have low thermal conductivity.
Examples of suitable plastic are Tygon and polycarbonate
resins.
The sealing band B2 is intimately bonded to the edges 215b
and 217b and bridges the gaps created by the spaces 219 and 220.
The sealing band B2 is a thin flexible resilient strip of
; metal formed to include spaced-apart channel parts 225 flanked by a
wide flat integral lip 229 which is bonded to an end edge face 215b or
217b, as the case may be.
Similarly, to the double glazed construction of Fig. 1, in
; the triple glazed construction, the sealing band B2 surrounds the
edges of the structure with the lips 229 sitting on and intimately
bonded to the edges 215b and 217b. The channel part 225 fits between
the faces 215a and 216a, bridging the gap 219. The channel 226 fits
between the faces 216c and 217a and bridges the gap 220 outside the
edge of the intermediate pane 216.
Variables
Glass
The panes may be of any glass used for glazing or display
screens, for example, any soda-lime or borosilicate glass, in com-
bination with any type of coating or tinting. The panes may vary in
thickness from 2 mm to 12 mm. The corners are radiused optionally
between 3 mm and 12 mm. By way of example, a 3 mm clear, tempered,
soda-lime glass is suitable. The edges should be ground slightly
and the corners rounded to 3 mm to 12 mm radius. This is a standard
procedure, prior to tempering, to reduce the risk of breakage and, at
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the same time, provides a suitable bonding surface for the sealing
band.
Sealing Band
The invention provides a spring band, resilient in all
directions, to remove stress from the bond line when movement occurs.
This is accomplished by a sealing band of the following construction.
Stresses from accumulated thermal movement and wind loads are
accommodated by flexing of the channel part of the sealing band.
Local stresses, directly at the bond side, are eliminated by matching
the coefficients of thermal expansion of the sealing band with the
glass and/or using bonds with enough malleability to allow ductile
flow.
The shape of the band, according to the invention, also
allows for continuous sealing around the unit without corner keys.
With the increasing use of higher performance glass, move-
ment properties become more critical. For example, the inside pane
can become very warm while the outside pane remains cooler, causing
thermal movement. The rigid nature of a conventional seal often
causes cracking of the inside panes. The seal of the invention does
not.
Another type of stress is the result of the thermal gradient
between the central area and the perimeter areas of the inner pane.
The applicant's sealing band being less thermally conductive,
minimizes this problem.
The sealing band is preferably formed from malleable stain-
less steel sheet of thickness from 4 to 20,000ths, desirably 5 to
7,000ths and having a range of Rockwell B hardness between 40 and
100, preferably 70 to 80. A preferred alloy is an annealed 304L
stainless steel.
Other metals may be used than those mentioned, for example,
aluminum, low carbon steel, or copper. But, these metals are less
desirable because of greater conductivity and corrodability and
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thermal coefficient of expansion.
A suitable sealing band may also be formed from plastic
material. In fact, such a band is useful to increase the overall
thermal performance of the insulating unit, by eliminating an
otherwise conductive path from inside to outside. This also
increases the strength of the unit by reducing temperature
gradients within the glass surface. High strength plastic sheet
having a thickness from 10 to 20,000ths with a metallic vapor
barrier electroplated or vacuum deposited on one surface may be
employed.
Suitable high-strength plastic sheel materials for the
band are, for example, polyurethane or nylon which, at the thick-
ness employed, are flexible. The plastics can be injection-molded
or vacuum-formed to the desired shape.
Problems with undesirable deformation of the band during
forming, e.g. puckering of the mounting lips, or otherwise, are
overcome by a forming method constituting a part of this invention.
A typical band has a trough of width 1/2 inch and depth 1/4
inch and the spacing of the corrugations from crest to crest is about
0.05 inches and the depth from crest to trough may be substantially
the same.
The trough may range in width from 1/8 inch to 2 inches,
with the corrugations on the 2 inch trough being from 0.045 to 0.220
in depth and the distance between the crests being from 0.045 inches
to 0.2 inches.
Bond
To achieve an effective bond between the sealing band and
the edge of the panes, it is desirable to select an alloy for the band
which closely matches the coefficient of thermal expansion of the
glass. For example, alloy #52 closely matches the coefficient of
thermal expansion for soda-lime glass.
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Bonding can also be performed with a low temperature glass
frit, e.g. a powdered high-lead glass, compounded to match the co-
efficient of thermal expansion for appropriate glass. It is applied
in a nitro cellulose vehicle and fuses at a temperature below that
which will adversely affect the temper of the glass. The alloy is
oxidized on the surface prior to bonding. The resulting oxide layer
is soluble in the molten glass.
Aluminum can be directly bonded to glass using an electro-
static process, but the aluminum band must be no thicker than 0.005
inches. At this thickness, the band yields before breaking the glass
when movement takes place due to thermal mismatch.
Other mismatched materials, such as stainless steel, can be
used with a graded seal. Interim malleable materials such as that
used for common tin-lead solders can be used. This requires a
metallizing of the glass to prepare it for fusing with the solder.
This can be done by atomic bombardment or vacuum metal deposits
followed by electroplating. These films are too thin to present
mismatch problems. It is likely that this process can be simplified
by combining it with another phase of production - possibly metalliz-
ing during tempering or the deposition of the low E coating. Heat
can be supplied by laser, electron beam, induction, resistance or
soldering irons.
The bonding of the band to the panes may also be performed
as follows.
The peripheral edges of each pane is metallized with a metal
layer chemically bonded thereto by ion-exchange. The lip or flange of
thetinned band is then juxtaposed to the metallized edge surface of
the pane and heat applied to fuse the band to the pane edge surface.
The resulting lamination is made up of the glass, the
metallizing layer, tin-lead solder and the metal of the band. The
coefficient of thermal expansion of the metal should be not more than
5% of that of the glass. The malleable nature of the solder inter-
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layer allows for a greater mismatch to allow normal grades of stain-
less steel to be used for the band. Preferably, the finished band
is ultrasonically cleaned and tinned before its application. The
metal band is juxtaposed to the edges of the pane, and heat and
pressure is applied resulting in bonding.
Vacuum
The vacuum required is 10 4 torr but to be safe the unit
should be pumped to 10 6 since components will leak gas during the
life of the unit. Special pumps and valves were used on the proto-
type but in production this too would likely be accomplished in the
coating stage for simplification. If coating is not applied in vacuum,
a simple pinch-off tube could be used, as is done in the TV tube
industry.
Baking of components is required to drive off surface gases.
This will require about 10 minutes, a short time compared to the 8 to
12 hour cure time required by conventional units. Helium penetra-
tion of glass was pointed out as a potential contaminant of the
vacuum but field studies indicate successful vacuum tubes in opera-
tion for 50 years. Evacuated solar collectors, a very similar
application, have a 10 year successful track record.
Getter
Active metal getters absorb gases from the cavity during its
life, helping to maintain the vacuum level. These are commercially
available and activated by heat as a final production function. This
is a well known science, backed up by 50 years of successful field
operation.
Manufacture
A preferred method of forming a metal sealing band is as
follows.
A strip is run through a series of roll-forming dyes to
provide the band with a trough which has a semi-circular or other-
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wise suitable curve in cross-section. The cross-section may be semi
circular, semi-oval or any other curved shape in which the curve is
continuous from one lip or flange of the band to the other.
The resulting band is then subjected to a progressive dye-
stamping operation to emboss the transverse corrugation in the trough
part while reducing substantially to a minimum any change in the
thickness of the band material.
A typical assembly method for an evacuated unit is as follows.
One pane is placed horizontally. lhe pads and balls are arranged into
position by longitudinal support arms coming from the side. A second
pane is placed horizontally on top of the assembly bearing the spacer.
The whole structure is prevented from moving horizontally by vertical
supports. The getter is placed in the cavity. Weight is applied to
the upper pane. The arms supporting the spacers are removed hori-
zontally. The sealing band is then bonded at the peripheral edge of
the panes, as described. A vacuum is drawn on the cavity through a
tube. A pinch off tube as familiar to the electronics industry may
be used. While the vacuum is being drawn the entire unit is heated
to drive off surface gases. The tube is pinched to provide a vacuum
tight seal. The getter is then activated by heating, for example, by
radio frequency.
Glazed Structure
; In assembling the glazed structure, as shown in the previous
Figures, an assembly jib is used to hold the pads and balls in place.
This is placed on the first pane and covered by the second pane.
Weights are applied to the second pane, the jig removed, and the
perimeter is bonded. A tube through the perimeter band is used to
evacuate the units.
Advantages
The multi-glazed units of the invention have the following
advantages:
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l. Larger life expectancy due to decreased moisture vapor
transmission rate of the seal.
2. Ease of manufacture because of the fewer components, the
corner design and the nature of the sealing band. The
structure lends itself to automated assembly.
3. Better thermal resistance due to decreased losses
through the perimeter seal and spacer.
4. Greater resistance to breakage because the glass is
relatively free floating.
5. Greater area of vision by reason of the elimination of
desiccant and conventional spacer bar.
6. Cost advantage through elimination of desiccant and
elimination of assembly labor.
7. The structure lends itself to gas-filling to improve
thermal and sound insulation, being capable of retain-
ing the gas permanently.
8. Transportation and installation is facilitated, the
edges of tne glass being protected by the sealing band.
In summary, the applicant's evacuated unit introduces a new
level of performance.
