Note: Descriptions are shown in the official language in which they were submitted.
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VACUUM INSULATED GLASS BUILDING COMPONENT
AND METHOD AND APPARATUS FOR ITS MANUFACTURE
The invention relates to a vacuum-insulated glass building ele-
ment which term is not intended to be lizN.ted to a vacuum-
insulated glass panes but also to another building components
consisting of a combination of vacuum insulated glass including
for example a solar module. The invention also resides in a
method and an apparatus for the manufacture of such a vacuum-
insulated building component.
The invention therefore relates to arrangements wherein at
least two glass plates or other areal glass structures with or
without the inclusion of another areal body are joined together
with a thin evacuated space therebetween.
Vacuum-insulated glass as such is known. It differs from con-
ventional insulated glass in that the space between the panes
is evacuated wherein, in normal insulated glass, it is filled
with a noble gas. Furthermore, the space between the glass
panes of vacuum insulated glass is substantially thinner than
in normal insulated glass, that is, only about 0.7 mm or less
since, in vacuum insulated glass, there is no convection in the
space betweeri the individual glass panes. The two individual
glass panes are supported with respect to each other by way of
supports distributed over the glass surface in a grid-like pat-
tern so that the ambient air pressure cannot press the panes
together. At their circumference, they are joined by a'vacuum-
sealed edge conxiection_
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In accordance with the known state of the art, vacuum insulated
glass panels are manufactured in that spacers are placed in the
predetermined grid-like pattern onto a first individual glass
pane and fixed by cementing and the second individual glass
pane is then placed on top. The top glass pane is provided at
its edge with a bore including a sealed-in evacuation nipple
which is fixed in position by glass solder or which is cemented
and to which a suction hose with a vacuum pump can be con-
nected. The two glass panes are then laser-welded along their
edges under atmospheric conditions using glass solder_ To this
end, the top glass pane is dimensioned so as to be smaller than
the bottom pane by several millimeters so that the edge of the
top pane is recessed with respect to the edge of the bottom
pane disposed below. In this way, the two glass panes can be
ls laser-welded together using glass solder by a laser beam di-
rected onto the arrangemeDt from the top.
After the laser welding of the panes, the space between the
panes is evacuated via the suction nipple. Evacuation is per-
formed for about two hours or longer during which time the
glass composite is maintained at a temperature of about 400 C
to about 450 C. Only in this way, volatile materials, mainly
water, which are adhering to the glass surfaces can be removed
from the space between the glass panes and a vacuum of suffi-
cient quality can be established.
This long period of evacuation at high temperature does not
only result in an expensive manufacturing process for the vac-
uum glass but also detrimentally affects the product quality.
Usually a reflective surface layer is vapor--deposited on the
glass surfaces facing the intermediate space a.f the glass panel
is to be used as a window panel in order to reflect heat radia-
tion whereby the heat protection function is improved. How-
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ever, because of the high temperatures used during evacuation
over a long period, highly effective coatings with a low emis-
sion degree (soft coatings) cannot be used. As a result, con-
ventional vacuum glass panels of the two-pane construction can
reach heat insulation values only compaxable with good conven-
tional insulated glass panels.
In addition, a high-temperature of about 450 C maintained dur-
ing evacuation over a period of about 2 hours results in the
de-tempering of single pane safety glass so that it substan-
ti.a].ly loses its safety glass property.
From EP-0 771 313, it is known to perform the laser welding of
the two individual panes of a vacuum insulated panel, which are
separated by an intermediate space and held in spaced relation-
ship by spacers arranged in the intermediate space, in a vacuum
chamber, so that the subsequent evacuation of the intermediate
space is no longer necessary. This printed publication ka.owever
recommends that during the welding of their edges within the
vacuum chamber the whole individual glass panes are heated to,
or slightly above, their annealing temperature in order to
avoid tension cracks. As a result, the problem that none of
the effective coatings for achieving low degrees of emission
can be used and safety glass single panes are also in this case
de-tempered.
However, whether the circumferential welding of the two single
panes are welded together in an azmospheric chamber with subse-
quent evacuation of the intermediate space or in a vacuum cham-
ber, in connection with conventional vacuurn-insulated glass
panels, there is always the substantial problem that the com-
posite rigid glass panel formed by the welding of the individ-
ual panes will not withstand the stresses to which it is sub-
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jected during use : The two individual panes separated by the
evacuated intermediate space during use assume different tezn-
peratures since the glass pane facing the room is warm and the
pane facing the outside air is cooler, wherein the use of a
coating for the reduction of heat losses by radiation increases
that temperature difference substantially. The temperature
difference between the individual. panes generated in this way
results in substantial mechanical tensions. This means that
conventional vacuum-insulated glass panels are limited in size
to certain maximum formats. Such vacuum-panels permit only a
certain relatively small window size. In addition, no reliable
information is available concerning- vacuum- ixzsu-lat'rorr---gi-cssa---
panels used under conditions where they are subjected to high
mechanical tensions.
It is therefore the object of the present invention to provide
vacuum-insulated glass building elements which reach heat insu-
lating values which are substantially better than those ob-
tained by good double pane insulation glass, but which, on the
other hand, require manufacturing expenditures which are at
least not essentially higher than the manufacturing expendi-
tures for a good double pane insulating glass panel, and which
can accommodate mechanical tensions occurring between the two
individual panes by temperature differences therebetween sub-
stantially better than conventional vacuum insulated glass pan-
els and which therefore promise a reliable long lifespan.
This object is solved in accordance with the invention by the
vacuuzn insulated glass building element as defined in claim 1.
3o
Advantageous embodiments of the invention are subject of the
subclaims.
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A particularly advantageous method for the manufacture of the
vacuum insulated glass building element according to the inven-
tion and a respective suitable and advantageous arrangement
therefore are subject of the method and the apparatus claims.
With the arrangement according to the present a.nvention, the
two individual panes are provided at their edges each with a
metal foil strip and the metal foil strips of the two individ-
ual panes are welded together. In this way, a durably vacuum-
tight connection between the individual panes is established
which however is not rigid but which can-accommodate relative
thermal expansions of the two individual panes. Such expansion
mov _men _s are accozcumodated without tensions, by the metal foil
strips which are interconnected by welding. In this way, a
vacuum-tight non-rigid edge cOnnection of the two individual
panes of the vacuum-insulated glass building component is pro-
vided which, during use, remains essentially free from mechani-
cal tensions also when the individual panes are subjected to
high temperature differences. For such an arrangement also a
reliable long life for the edge connection can be considered to
be no problem and the formatiou, of cracks as a result of ther-
mal effects on the panes which could lead to a loss of the vac-
uum between the panes is not to be expected.
'As essential advantages of the arrangement according to the in-
vention, not only a predictably long life of the vacuum-
insulated glass panel according to the invention is obtained in
this way, but also a limitation of the panel to small formats
is eliminated as it exists in connection with the rigid conven-
tional edge connections of conventional vacuum-irzsulated glass
panels obtained by glass-welding of the two individual panes.
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The glass panes can be joined along their edges with the metal
foil strips either with the aid of glass solder by melt welding
or by "coid" welding by means of ultrasound. In this connec-
tion, ultrasound welding is preferred since it causes no ther-
mal stresses. In addition, the ultrasound welding procedure is
simpler than the melt welding with glass solder.
This results in'a further substantial advantage of the vacuLtm-
insulated glass building element according to the invention in
that the ultrasound welding causes no thermal stresses, and
does not detrimentally affect the glass panes. 'If one of the
glass panes consists of safety glass,-the glass pane is not de-
tempered by the 'effects of heat and*the safety glass structure
remains unchanged. In addition, highly effective low-emission
coatz,ngs can be used which are not affected by the manufacture
of the edge joint so that very high heat insulation values are
obtained for the vacuum insulated building element.
The manufacture of the edge connection is possible by a rela-
tively simple process. The ultrasound welding (or also the
glass solder welding) of the glass pane edges with the metal
strip can occur under atmospheric conditions. The subsequent
welding of the metal foil strip areas which project from the
glass pane edges and are connected to the glass pane edges can
be performed in a vacuum chamber by laser welding so that sub-
sequent evacuation of the space between. the glass panes is not,
necessary. Subsequent7.y, outside the vacuum chamber, the welded
excess metal foil strip areas can be bent over toward one or
the other side and the edge joint is completed.
The metal foil strips are preferably arranged at the sides of
the glass panes which fac-e each other. Before the welding of
the metal foil strips in the vacuum chamber expediently a get-
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ter matexi.al is applied to one of the metal- strips which, with
respect to the welding seam to be formed, faces. the interior of
the space between the panes for the absorption of moisture
molecules possibly present in the space between the glass
panes.
An exemplary embodiment of a vacuum-insulated glass building
element according to the invention and a method and an appara-
tus for the manufacture thereof will be described below in
greater detail with reference to the accompanying drawings.
The drawings show in:
Fig. 1 in cross-section an edge area of a vacuum insulated
glass building element according to the invention,
Fig. 2 the two individual glass panes of the building element
with metal foil strips attached thereto before the assembly,
Fig. 3 the assembled individual glass panes after the welding
2o of the projecting areas of the metal foil strips,
Fig.. 4 a schematic cross-section of the edge area of a vacuum
insulated glass building element according to the invention
forming a solar module,
z5
Fi,g. 5 a variation of the arrangement according to Fig. 1,
Fig. 6 a schematic diagram which clarifies the manufacturing
procedure of vacuum insulated building elements according to
30 the invention,
Fig. 7 schematically the cleaning step of the method in a first
vacuum chamber, and
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Fig. 8 schematically the laser welding stage of the method a.~a a
second vacuum chamber.
Fig. 1 shows, in cross-section, the edge area of a vacuum insu-
lated glass building element in the form of a vacuum insulated
glass panel with a finished edge connection. The arrangement
comprises a cover pane 1(outer pane) and a bottom pane 2 (in-
ner pane), which are separated from each other by an intermedi-
ate pane space 3. In the intermediate pane space 3, there is a
vacuum. The two panes 1 and 2 are held at a predetermined dis-
tance from each other by spacers 4 which are fixed to the bot-
tom pane 4 in a grid-like arrangement- f-or-exampl-e--by--eeme-nt3ng--
and on which the cover pane I is supported. The spacers may=be
small glass cylinders as shown but they may also be in the form
of balls and they may also consist of metal.
The cover pane 1 and the bottom pane 2 each may have a thick-
ness of 4 mm and the intermediate space 3 may have a thickness
of preferably in the range of 0.7 mm to 1 mm.
At the edge of each of the two panes 1, 2, a metal foil strip 5
is attached in a vacuum-tight manner. Prefexab1y, the metal
foil strips 5 are attached at the sides" of the two panes 1, 2
facing the intermediate space 3.
The metal foil strips 5 may be connected to the respective
panes either by welding by means of a glass solder, preferably
however by ultrasound welding. The ultrasound welding occurs
with the interposition of a thin aluminum foil strip 6 between
the respective metal foil strip 5 and the glass surface,
wherein the aluminum is tightly joined to the glass surface and
also to the other metal of which the metal foil 5 consists,
preferably stainless steel. The areas of the metal foil strip
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which are attached to the two panes and which project over
the glass pane edges are compressed and welded together pref-
erably by laser welding. Herein, a getter material 8 is ar-
ranged inward of the welding seam 7 between the metal foil
5 strips 5 that is still within the intermediate space between
the panes which getter material has been applied to the lower
metal foil strip before the welding. The welded projecting area
of the metal foi7, strips 5 is bent onto the edge surface of the
lower pane 2. The getter material does not need to be arranged
between the panes as shown (where with a thin intermediate
space, there is generally no space), but it may be disposed in
the bent over area of the welded metal foil strips.
Figs. 2 and 3 show pxe-s tages of the finished edge connection
of the vacuum insulated glass building element according to
Fig. 1.
Fig. 2 shows the two still individual panes, that is the cover
pane 1 and the bottom pane 2, each with the metal foil strip 5
welded to the respective edge. On the bottom pane 2, further-
more, the spacers 4 are already in place.
Fig. 3 shows the joined arrangement of the top pane 1 and the
bottom pane 2 with the metal foil strips 5 welded thereto,
wherein the areas of the metal foil strips 5 projecting beyond
the pane edges are, welded together by a welding seam 7. By
bending the welded projecting areas of the metal foil strips 5
onto the edge surfaces of the bottom pane 2, the edge connec-
tion is completed as it is shown in Fig. 1.
Fig. 4 shows an arrangement as it is shown in Fig. 1, wherein
however the bottom pane 2 is-combined with an additional module
(or is formed as such), here with a solar photo voltaic module
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10. Herein, the photo voltaic module 10 forms with the bottom
pane 2, a compound arrangement. If as shown, in the embodiment
of Fig. 4, the additional module consists fully or partially of
glass, the metal foil strips may also be attached as shown in
Fig. 4 or, like in the basic embodiment according to Fig. 1, to
the side walls of the cover pane 1 and the bottom pane 2 or,
respectively, the additional module. which faces the intermedi-
ate space 3 between the panes. However, if the additional mod-
ule is not suitable for a vacuum-tight attachment of the re-
spective metal foil strips 5, the arrangement as shown in Fig.
5 and described below may be selected. Generally, however the
particular pane, in this case, the bottom pane will form the
additional module by integration of a particular function.
Fig. 5 shows a modified embodiment of the vacuum sealed edge
jointure of the arrangement according to Fig. 1. It differs
from the embodiment of Fig_ 1 in that the metal foil strip 5 is
not attached to the facing surfaces of the individual glass
panes 1 and 2, but to their outer surtaces. This embodiment
according to Fig. 5 is possible and equally good with respect
to the quality of the vacuum sealed edge connection as the em-
bodiment of Fig. 1, but in that case, the outer surfaces of the
finished vacuum insulated glass element is not smooth fully to
the outer edge thereof but has a raised edge area because of
the metal foil strips 5 extending along the edge. This could
be objectionable for some applications, which is why this em-
bodiment appears to be less preferred.
The preferred material for the edge foil strips 5 in all em-
bodiments is stainless steel.
As apparent from figures 1 to 3, the outer gap between the in-
dividual panes 1 and 2 and the metal foil strips 5 attached
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thereto can be sealed in the area between the respective indi-
vidual outer pane edges and the connection or, respectively,
weld areas to the glass pane surface by a filler material 9.
This filler material has two functions. It ensures a long-term
vacuum sealing by protecting the weld between the metal foil
strips and the glass from outside influences and it also re-
duces mechanical stresses. Furthermore, it protects the pane
edges from mechanical stresses during the bending over of the
welded metal foil strips.
io
Fig. 6 shows the procedure of a preferred manufacturing method
for the above-described vacuum insulated building elements in a
schematic block diagram.
In a first method step A, the two individual glass panes are
prepared under atmospheric conditions. This includes the con-
nection of the metal foil strips to the individual glass panes
and the attachment of the spacers to the bottom pane as well as
the application of the getter material, if used.
The second method step B resides in the cleaning of the two in-
dividual panes, particularly the removal of water molecules
from the pane surfaces. Special coatings of the panes bind wa-
ter molecules which are difficult to remove therefrom. Conven-
tionally, this requires heating to high temperatures over an
extended period, which, however is undesirable since high tem-
peratures, particularly when effective over an extended period,
destroy high quality coatings for reducing the degree of emis-
sion (so-called low E-layers) and also the glass structure, for
example, that of safety glass, as rnentioned already earlier.
This cleaning step is performed with the method according to
the invention, without temperature effects, by ion scattering,
wherein the ions absorb the moisture molecules and carry t_hem
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away, or by plasma cleaning which is also called plasma etch-
ing. This method step is performed in a first vacuum chamber
under constant suction in order to remove any moisture released
from the pane surfaces. It is very important hereiza, that in
each case, both sides of each individual pane are cleaned that
is the moisture is removed also from that side which does n.ot
delimit the evacuated space between the panes. This is neces-
sary because any moisture input into the high vacuum chamber,
in which the laser welding of the metal foil strips takes place
must be carefully avoided since otherwise the high vacuum is
detrimentally affected.
Fig. 7 shows schematically the cleaning stage according to the
method step B in the first vacuum chamber by ion scattering,
or, respectively, vacuum etching on both sides of the plate
wherein the ion scattering or, respectively, the vacuum etching
occurs along a line over the whole width of the plate while the
glass pane is moved on a transport means 11 through the first
vacuuzn, chamber 12.
The third method step C is the laser welding of the metal foil
strips in a second vacuum chamber 13, which is schematica],ly
shown in Fig. 8 in a sectional view. Herein, first., the lower
pane 2 is introduced into the vacuum chamber 13 and subse-
quently the upper pane is introduced and placed onto the lower
pane. The vacuum chamber 13 is provided at its topside along
all four corner areas with a, in each case, line-like window 14
which, of course, is interrupted by bridge areas of supporting
material as necessary for the integrity of the top wall of the
vacuum chamber 13. A laser cannon 15 is arranged on the out-
side, that is, above the vacuum chamber 13 and movable along
the window 14 in order to direct the laser beam through the
window 14 onto the metal foil strips to be welded_ The pane
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arrangement is disposed within the vacuum chamber 13 on a cor-
responding carriage which is movable in the plane of the pane
since, because of the design-based interruptions of the wi,xidow
14, a certain movability of the pane arrangement is necessary
in addition to the movability of the laser cannon.
This arrarigeznent has essential advantages. Since the laser can-
non 15 is arranged outside the vacuum chamber 13 and is movable
along the window 14, no mirror or any other optical elements or
mechanisms are needed within the vacuuin chamber so that the
vacuum chamber can have a minimum volume. The required length
and width of the vacuum chamber is based on the dimensions of
the largest pane arrangement to be welded therein and the
height of the vacuum chamber is determined only by the thick-
ness of the pane arrangement and the height required for the
carxiage by which it is supported. Because of the movability
of the laser cannon 15 also complicated laser-optical equip-
ment, particularly mirror mechanisms, are not needed outside
the vacuum chamber either which simplifies the arrangement.
In the last method step D, after the removal of the pane ar-
rangement with the welded metal foil strips out of the second
vacuum chamber 13, a final treatment of the edge areas is per-
formed, that is, the application of a filler material 9 and the
bending of the laser-welded projecting areas of the metal foil
strips, and, if desired, the installation of a protective cover
on the finished edge connection.
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