Heat insulated wall

A heat insulated wall having two surface layers disposed at a distance from one another and are at least substantially vacuum-tight in construction. The two surface layers together with an at least substantially vacuum-tight connection element enclose an evacuable space that is filled with an evacuable thermal insulation material. The surface layers have angled sections with free ends directed away from the space and on which the connection element is disposed and is fastened in a vacuum-tight fashion to the angled sections.

BACKGROUND OF THE INVENTION 
Field of the Invention 
The invention relates to a heat insulated wall having two surface layers 
disposed at a distance from one another and being at least substantially 
vacuum-tight in construction which together with an at least substantially 
vacuum-tight connection element enclose an evacuable space which is filled 
with an evacuable thermal insulation material. 
With heat insulated walls based on vacuum insulation technology it is known 
for the outer surface layers, which are at a distance from one another, to 
be connected to one another in a vacuum-tight fashion by a connection 
profile which is substantially U-shaped in cross section. The connection 
profile is inserted between the surface layers in such a way that the free 
leg ends thereof face the edges of the surface layers and end 
substantially flush with them. With this type of connection of the two 
surface layers it is absolutely necessary to furnish the base of the 
connection profile with a thickness of material which must lie within the 
same order of magnitude as that of the surface layers. This is necessary 
in order to achieve some rigidity for the tensioning forces which are 
required as part of the manufacturing process and which have to be exerted 
exclusively outside the insulation compartment, owing to its lack of 
accessibility, on the heat insulated wall. As a consequence of the 
increased thickness of material in the area of the base of the connection 
profile, and when using inexpensive thermal insulation materials which 
serve as both supporting and insulating material and are to be introduced 
into the space between the surface layers, such as open-cell polyurethane 
foam or open-cell polystyrene foam or the like, a heat bridge is produced 
which has a considerable adverse effect on the insulation capacity of the 
heat insulated wall. To avoid this adverse effect, the known walls are 
filled with expensive fiber materials that in addition, owing to their 
relatively high specific weight, represent a marked increase in weight of 
the walls. Thereby, considerably hindering the handling of the walls in 
production or, where the latter are employed, for example, for a 
refrigeration device, such as a household refrigerator or home freezer, 
considerably hindering the mobility of the device. 
SUMMARY OF THE INVENTION 
It is accordingly an object of the invention to provide a heat insulated 
wall that overcomes the above-mentioned disadvantages of the prior art 
devices of this general type, which has simple constructional measures. 
With the foregoing and other objects in view there is provided, in 
accordance with the invention, a heat insulated wall, including: an at 
least substantially vacuum-tight connection element; an evacuable thermal 
insulation material; and two surface layers disposed at a distance from 
one another and being at least substantially vacuum-tight in construction, 
the two surface layers together with the at least substantially 
vacuum-tight connection element enclose an evacuable space filled with the 
evacuable thermal insulation material, the two surface layers having 
angled sections with free edges directed away from the evacuable space, 
the at least substantially vacuum-tight connection element disposed on and 
fastened to the angled sections in a vacuum-tight fashion. 
The object is achieved in accordance with the invention by the surface 
layers having along their free edges an angled section which is directed 
away from the evacuable space and on which the connection element bears 
and is fastened in a vacuum-tight fashion. 
With a construction technique of this kind it is possible without exception 
to employ individual parts of simple geometry in the form of planar sheet 
metal sections which are inexpensive to produce. In addition, the sections 
on the surface layers and the connection element which have to be 
tensioned with respect to one another using tensioning tools are readily 
accessible, so that, firstly, very simple tensioning tools can be employed 
owing to the ready accessibility of the tensioning points and a connection 
element equipped with a sheet-like wall thickness can be used, since the 
element no longer has to be used to absorb any tensioning forces. The use 
of a connection element equipped with a sheet-like wall thickness gives 
the possibility of filling the space between the surface layers with an 
inexpensive thermal insulation material, such as open-cell polyurethane 
foam or open-cell polystyrene foam, for example, without thereby adversely 
affecting the heat insulation properties. When the thermal insulation 
materials are used the sheet-like connection element constitutes only a 
negligible heat bridge. 
In a preferred embodiment of the subject matter of the invention it is 
provided that the connection element is configured as a flat profile with 
two edge strips having at least essentially the same width and thickness 
of material as the angled sections and between which there is disposed a 
sheet-like intermediate piece which bridges at least the evacuable space. 
Using edge strips whose thickness of material is in the same range as that 
of the angled sections, the connection element fabricated, for example, 
from stainless steel or steel sheet, can be fixed in a particularly 
reliable and rapid manner by welding to, for example, surface layers 
fabricated from stainless steel or steel sheet, and with high processing 
reliability. The sheet-like intermediate piece at the same time provides 
coverage of the space between the surface layers with minimal thermal 
conduction. 
In a further preferred embodiment of the subject matter of the invention it 
is provided that the sheetlike intermediate piece with its lateral 
sections is fastened in a vacuum-tight fashion to the surface layers as a 
spacer between the edge strips and the angled sections. 
The results of this are individual parts which are particularly simple and 
inexpensive to produce and which, moreover, can be joined in a 
particularly functionally reliable manner and can be connected to one 
another with particular processing reliability. 
The vacuum-tight fastening of the spacer can be produced both with 
particular processing reliability and in a particularly inexpensive way if 
in a subsequent advantageous embodiment of the subject matter of the 
invention it is provided that the vacuum-tight fastening of the spacer is 
brought about by welding. 
In terms of fabrication the connection element is easy to produce and 
particularly simple to handle if it is provided that the connection 
element is composed of a plurality of longitudinal sections. 
In a subsequent preferred embodiment of the subject matter of the invention 
it is provided that the longitudinal sections are guided in one piece and 
jointlessly over the corner regions of the walls. 
Therefore, potential problems with the leak-tightness of the vacuum 
insulation as a result of points of connection accumulating in the corner 
regions, in the form, for example, of accumulations of weld seams in the 
case of surface layers and connection elements fabricated from stainless 
steel or steel sheet, are made less acute. The one-piece corner profiles 
also ensure that the desired geometry, which is also required on 
functional grounds, is always maintained, since the corner profiles can be 
employed, for example, as preformed or prefabricated components and the 
corner on the heat insulation walls need not be brought about only by 
profile sections which are not joined until the fabrication stage. 
Moreover, the one-piece corner profiles make it possible to use different 
corner configurations, such as rounded corners, for example, which permit 
a continuous, uninterrupted and therefore, in processing terms, reliable 
welding operation when the surface layers are welded to the connection 
profile. 
In a further preferred embodiment of the subject matter of the invention, 
it is provided that the longitudinal sections are each supported by a 
support element which is fastened in a vacuum-tight fashion to the surface 
layers for supporting the region where two longitudinal sections are 
joined to one another. 
By introducing such support elements, whose wall thickness lies, for 
example, in the same order of magnitude as the thickness of the material 
of the surface areas, the longitudinal sections can be adjusted with 
particular ease and rapidity with respect both to one another and to the 
surface layers, thereby providing a significant increase in the speed of 
the fabrication process. Furthermore, the support elements also have the 
capacity to absorb tensioning forces which may be applied as a result of 
the production process. 
In a subsequent preferred embodiment of the subject matter of the invention 
it is provided that the longitudinal sections are covered where they join 
with one another in each case by a cover element which is connected in a 
vacuum-tight fashion to the surface layers and to the support element. 
By using cover elements at the joint sites between the joined longitudinal 
sections, the latter can be connected to one another in a particularly 
purposeful and fabrication-friendly manner to form a vacuum-tight 
connection element. The vacuum-tight connection of the cover element to 
the support elements fastened in vacuum-tight fashion to the surface 
layers results in a vacuum-tight assembly being produced even when there 
are joint gaps of different widths between the joined-together 
longitudinal sections as a consequence of their production tolerances. 
The heat insulated walls can be produced in a particularly reliable manner 
in processing terms by mass production if it is provided that the surface 
layers, the connection element, the support element and the cover element 
are formed from weldable metallic materials. 
A particularly environment-friendly refrigeration device possessing a high 
heat insulation capacity, having a heat insulated housing and a functional 
compartment which is disposed therein and can be closed by a heat 
insulated door, can be produced if in a subsequent preferred embodiment of 
the subject matter of the invention it is provided that the heat insulated 
housing and the door are configured as set forth in the invention. The 
high heat insulation capacity also makes it possible to reduce the wall 
thickness of the heat insulated housing and therefore enlarge the useful 
capacity of the cooling or freezing compartment with unchanged external 
dimensions. 
In a similarly, particularly environmentally compatible manner, with a 
relatively high heat insulation capacity and an increased useful capacity 
with unchanged external dimensions it is possible to produce an oven 
muffle for a domestic oven, having a heat-insulated oven muffle which can 
be closed by a door, if in a final preferred embodiment of the subject 
matter of the invention it is provided that the oven muffle is configured 
as set forth in the invention. 
Other features which are considered as characteristic for the invention are 
set forth in the appended claims. 
Although the invention is illustrated and described herein as embodied in a 
heat insulated wall, it is nevertheless not intended to be limited to the 
details shown, since various modifications and structural changes may be 
made therein without departing from the spirit of the invention and within 
the scope and range of equivalents of the claims. 
The construction and method of operation of the invention, however, 
together with additional objects and advantages thereof will be best 
understood from the following description of specific embodiments when 
read in connection with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In all the figures of the drawing, sub-features and integral parts that 
correspond to one another bear the same reference symbol in each case. 
Referring now to the figures of the drawing in detail and first, 
particularly, to FIG. 1 thereof, there is shown a heat insulated housing 
10 which can be used for a domestic refrigeration device, such as a 
household refrigerator or a home freezer. The insulated housing 10 has a 
storage compartment 12 that is accessible via an access opening 11 and is 
configured as a cooling or freezing compartment. The compartment 12 is 
lined with an inner surface layer 13 which serves as an interior lining 
that is configured as a pipe structure and consists, for example, of 
stainless or corrosion-protected steel sheet with a thickness of material 
of, for example, 0.4 mm. The inner surface layer 13 is provided at its end 
section facing the access opening 11 with an angled section 14 that is 
disposed essentially perpendicular to the inner surface layer 13. The 
surface of the angled section 14, facing away from the storage compartment 
12, serves as a bearing surface 15 whose free edge 16 delimits the free 
opening cross section of the access opening 11. The inner surface layer 13 
is enveloped by an outer surface layer 17 that serves as an exterior 
lining of the housing 10. The walls of the outer surface layer 17 are 
disposed at a distance from the walls of the inner surface layer 13 so 
that the two surface layers 13 and 17 are joined like two pipes plugged 
into one another. The outer surface layer 17 is provided at its end 
section facing the access opening 11 with an angled section 18. The angled 
section 18 is produced by noncutting deformation of the outer surface 
layer 17. The angled section 18 has a free edge 19 facing away from the 
surface layer 13, and whose outer surface, like that of the angled section 
14, serves as a bearing surface 20. The bearing surface 20 like that of 
the inner surface layer 13, is disposed essentially perpendicular to the 
surface of the outer surface layer 17 and extends at essentially the same 
height as the bearing surface 15 on the inner surface layer 13. Between 
the inner surface layer 13 and the outer surface layer 17, which surrounds 
it in the manner of an envelope, the equal distancing of the walls of the 
outer surface layer 17 from the walls of the inner surface layer 13 
produces a space 21. The space 21 is filled with an evacuable thermal 
insulation material 22, such as open-cell polyurethane foam or open-cell 
polystyrene foam, and which is closed in a vacuum-tight fashion on its 
rear side opposite the access opening 11. On the side of the access 
opening 11, the space 21 is closed off in vacuum-tight fashion by a 
connection element 23 which extends along the angled sections 14 and 18, 
respectively, and at its free edges is fastened in vacuum-tight fashion to 
their bearing surfaces 15 and 20, respectively. 
The connection element 23 is of essentially flat-profiled construction and 
is composed of a plurality of sections 24 that extend in one piece and 
jointlessly over the corner region of the housing 10. The sections 24 are 
fabricated from a sheet-like material such as, for example, a stainless 
steel sheet with a thickness of material of 0.1 mm. The sheet-like 
sections 24, which extend up to the free edges of the angled section 14 or 
18, respectively, are joined to one another by their end sections 25 to 
form a joint 26. The end sections 25 being supported at the joint 26 by a 
support element 27 having a substantially U-shaped cross section or 
profile. The support element 27 is fabricated, for example, from a 
stainless steel sheet lying within the range of thickness of material of 
the surface layers 13 and 17. The support element 27 is fastened in a 
vacuum-tight fashion by its legs to the inside, facing the space 21, of 
the surface layers 13 and 17, by a weld seam S1 (FIG. 2). In addition to 
the sheet-like sections 24, the connection element 23 also includes edge 
strips 28, which lie within the range of thickness of material of the 
surface layers 13 and 17. The edge strips 28 have essentially the same 
width as the bearing surface 15 or 20, respectively, and like the sections 
24, are guided continuously in one piece over the corner regions of the 
housing 10. The edge strips 28 are also fastened in vacuum-tight fashion 
along the bearing surface 15 by a weld seam S2. The sheet-like sections 24 
are disposed as a spacer between the angled section 14 and 18, 
respectively, and the edge strips 28 are connected in vacuum-tight fashion 
by the weld seam t2 to the surface layer 13 or 17, respectively. The edge 
strips 28 are in each case shortened at the joint 26 essentially by half 
the width b (FIG. 2) of a cover element 29 which lies within the range of 
thickness of material of the surface layers 13 and 17. The cover element 
29 is fabricated, for example, from stainless or corrosion-protected steel 
sheet, and which by virtue of the shortening of the edge strips 28 is able 
to fill the gap formed relative to the sections 24. The cover element 29, 
which ends essentially flush with the free edges of the angled sections 14 
and 18, serves for vacuum-tight coverage of the joint 26 of the end 
sections 25. The vacuum-tight assembly is produced using a weld seam S3 
which crosses the weld seams S2. The weld seam S3 extends over the entire 
length of the cover element 29 and connects the cover element 29 in a 
vacuum-tight fashion to both the angled sections 14 and 18 and to the base 
of the U-shaped support element 27. By using the cover elements 29 
employed at the joints 26 of the sections 24, in combination with the edge 
strips 28 and the sheet-like sections 24, the two surface layers 13, 17 
are connected to one another in a vacuum-tight form with minimal thermal 
conduction between them, so that in cooperation with the means which are 
not shown but which on the rear, connect the two surface layers to one 
another in a vacuum-tight fashion, the space 21 is closed off in such a 
way that it can be evacuated. 
In a modification of the present connection element 23, it would be 
conceivable to produce the edge strips 28 by folding over, several times, 
the length-wise edges of the sheet-like sections 24. 
The novel heat insulated wall described in the example of the heat 
insulated housing 10 for a household refrigerator or home freezer is also 
suitable for constructing a door of a domestic refrigeration device and 
for producing a heat insulated oven muffle which is employed in connection 
with a domestic oven. 
The latter application requiring full adaptation of the thermal insulation 
material serving as a support material in the evacuated space to the 
operating temperatures that commonly prevail in ovens.