Note: Descriptions are shown in the official language in which they were submitted.
~ CASE 2527
This invention relates to refrigera-ting appliances
generally of a domestic type. It particularly relates -to
such appliances wherein an insulating foam is expanded ~ithin
cavity walls of the appliance. Still more particularly it
relates to improvements in the sealing of thermal breaker
strips that join the cavity walls whereby the breaker strips
may be employed effectively to retain the foam during the
insulating process.
In appliances of the above type two related methods
are commonly employed for the in situ type of foam
insulation o~ the cavity walls. In both methods a reactant
system is compounded; in the one method the system is
allowed to react partially external to the cavity, and prior
to set up the relati-vely viscous mixture is injected into
the cavity. In the second method the liquid reactants are
merely poured through one or more openings in the back of
the cabinet; the mobile liquids runs down the inner surfaces
of -the cavity walls and tends to expand from the bottom of
the cavity upwards. This second method is particularly
testing of any imperfections in the wall structure, for the
pressure generated as the foam expands tends to force the
mobile liquid through only minute fissures. Unfortunately
it is precisely in the area of the breaker strip joints
where the liquid reactants tends to drain and accumulate, the
cabine-t during this foaming method being oriented with
its open front downward. Temporary rubber gaskets have been
employed to seal in this area. However, these require
frequent replacement due to the adherence of foam to the
gasket. Moreover the fitting and stripping of a -temporary
gasket is found to be time consuming. Latterly a-ttempts
have been made to use the breaker strips themselves either
as a primary sealant means so as to con-tain the foam, or as
CASE 2527
a secondary sealant means in conjunction with, for example,
fibre glass batts located within the cavity immediately to
the rear of the breaker strip. However, the reject rate in
these methods due to foam escape marring the external surfaces
of the appliance is relatively high, and it is usually
necessary to provide a temporary tape seal between the edges
of the breaker strip and the appliance walls.
In Canadian Patent Application Serial No. 264,930 Eiled
October 28, 1976, titled "Foam In Place Breaker Strips" to
Kuskowski, commonly assigned herewith, improvements to
breaker strips are described which permit the effective con-
tainment of liquid foam generating materials along the
length of the breaker strips. The aforesaid strips are pre-
ferably extrusion moulded for reasons of economy. In use,
strip material is cut to length to provide Gne strip for
each of the four sides of the cabinet opening; the in-
dividual lengths are sprung into position with the ends
abutting, thus forming four mitered corner joints. Dif-
fic~lty has been experienced in providing a seal for these
abutting joints. The above-mentioned methods, i.e., the use of
internal fibre batts or temporary tape seals may be restored
to. In addition, it was proposed in Canadian Pat., 845,677,
issued June, 1970 to Pulaski, to inject a small quantity of
a fast rise time foam into the cavity in the vicinity of the
joints 50 as to provide an internal seal. None of these
methods have proved to be entirely satisfactory.
I have found that a suitable corner joint seal can be
rapidly and easily made by introducing a pad of a com-
pressible, resilient material between the abutting end
portions of the breaker strips, so as to be tightly nipped
in the joint along the length thereof. I have found that
a particularly suitable sponge material for this purpose is
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CASE 2 5 2 7
a foamed polyethylene having a density of about 2.0 lbs/cuEt~,
for example as sold under the trade mark ETHAE~OAMo Other
resilient foamed polymers, particularly foamed polyolefins
or polyurethane that are unaffected by the foam providing
materials used in -the insulation process will in general
be suitable.
In accordance with the present invention there is
provided an improved method for applying foam-in-place
insulation to a cavity formed between an encasement of a
refrigerating apparatus and a nesting liner therefor, the
encasement and liner being bridged at their front edge
portions by a thermal breaker strip which includes at least
two ends abutting to form a joint. The improvement comprises
sealing the joint by compressing a pad oE an inert, re-
silient material between the abutting ends along the length
of the joint prior to introducing the foam in place in- ;
sulation.
My invention will be further described in relation
to a preferred embodiment thereof, as illustrated in the
accompanying drawing wherein.
Figure 1 is an exploded perspective view of a
refrigerator outer cabinet, inner cabinet and breaker strips;
Figure 2 is a view along ]ine 2-2 of Figure 1 with
the components in assembled relationship;
Figure 3a is a partial section through the upper
right~hand corner of the cabinet of Flgure 1, with the
components in assembled relationship;
Figure 3b is similar to Figure 3a, but wherein an
insulating foam material has been introduced into the cavity
of the refrigerator;
Figure 3c is similar to Figure 3b, but shows a
finished corner assembly.
~ CASE 2527
Refering to E~igures 1 and 2 in detail, a refrigerating
appliance which is represented generally the numeral 10,
comprises an open front box-shaped encasement structure 12
and an open front liner structure 14 nesting therein and
spaced therefrom by a cavity 16. The two wall structures
are preferably folded from steel sheet. In order to thermally
insulate the liner, cavity 16 is normally filled with an
insulating material. The forward edge 20 of liner 14 -
connects to encasement 12 by a thermal breaker strip 40,
this generally being formed from a thermoplastic material
such as polystyrene, ABS etc.
In one commonly employed process for insulating cavity
16, the structure of Figure 1 is placed Eace downwarcls
upon a male mould so as to support liner 14, and a reactive
liquid composition is metered into one or more openings
in the back of encasement 12. The liquid runs down the
inside surfaces of the encasement and liner 14, expanding
rapidly and generating appreciable pressure. At least a
portion of the reactants, whilst still in a mobile, llquid
state, flows over the interior surface of breaker strip ~10.
The form of breaker strip 40 illustrated is that
taught in the previously referred to Kuskowski patent
application. This is deemed to be preferred in providing
an effective seal along the length of the breaker strip,
both where it seals to outer encase~ent 12 and to inner
liner 14. Other forms of breaker strip may be employed,
however. This preferred form of breaker strip 40 includes
a double clawlike seal 42 which connects to the forward
edge 20 of liner 14. The opposed side of breaker strip
30 40 includes a J seal 44 which wedges into a channel 24
formed along each frontal wall portion of encasement 12
within cavity 16 so as to retain the breaker strip securely
~ ~ ~q'~ ~ CASE 2527
in positionl and a flange seal ~6.
The assembly of the component parts o refrigerating
apparatus 10 prior to the foam insulation step is generally
known to those in the art. Briefly, liner 14 is supported
in spaced, nesting relation wlthin encasement 12. The
open ends of channels 24 proximate the fou]- corner dis-
continuities are filled with a mastic composition. Ap-
propriately sized lengths of ~reaker strip 40 are then
positioned to bridge between liner 14 and encasement 12,
with the ends of the breaker strip abutting in a miter
joint in each of the four corners, and the miter joints
sealed. The assemblage is supported on a mouldiny jig
(not illustrated) and placed with the open front face
downward, following which foam or foam-producing liquid
is introduced into cavity 16. For further details of this
general procedure reference may be had to Canadian Patent
808,613, issued March 18, 1969 to Gobeille.
In the practice of my invention breaker strips are
cut to length so that when assembled in position they form
a frame wherein the ends are closely abutting in the
corner joints. Some latitude is possible however, and a
gap of some 1-2 mm is quite tolerable. The sealing of the
corner joints is best seen with reference to Figures 3a-3c.
In Figure 3a a pad 50 of foamed polyethylene having a
density of about 2,0 lbs/cuft. is shown as being nipped
tightly between abutting ends of two adjacent portions of
breaker strip. The breaker strip may be assembled about
pad 50 or alternatively pad 50 may forced into position
subse~uent to the assembly of the breaker strips. No
special tool is required for this purpose, a piece of sheet
metal having a width approximately coextensive with the
lenyth o-f the joint to be made sufficiny. It may be
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- CASE ~527
desirable to adhere pad 50 to one end of a breaker strip
prior to bringing the end of a second strip into abutment
-therewith.
When foam is introduced into cavity 16 the pressure
generated appears to flatten the edge portion of pad 50
which projects within the cavity, as seen in Figure 3b,
thus probably assisting in sealing the joint and reducing
the possibility of the escape of foam or foam producing
liquid. Extensive trials have shown an extremely low
failure incidence, and in those cases wherein there has
been a foam escape this has generally been found to be
due to grossly oversized openings between abutting ends
of the breaker strip at the corner joints. Following the
set up of the ~oam within cavity 16 and the removal of
the refrigerating apparatus from the moulding jig, the
edge portion of pad 50 which projects from the exterior
of the joint, i.e. towards the interior of the refrigerator,
is trimmed off with a sharp knife closely adjacent the
breaker strips 40 or pushed in cavity 16, if preferred.
As an alternative procedure the projecting edge portion
may be pushed into cavity 16. Subsequently a thin layer
of a sealant material such as a room temperature
vulcani~ing silicone polymer is applied, shown as 55 in
Figure 3c.
Whilst my invention has been specifically described
in terms of sealing a corner joint wherein the ends of
adjacent breaker strips are mitered, it will be apparent
that my method can be employed to seal other types of
abutting joints as are commonly employed to join the ends
of injection moulded type breaker strips. The scope of my
invention is not limited to the specific and preferred
embodiment, but according to the embodiments thereof
described in the appended claims.
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