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@1.29, 194e.
Filed May e, 1944
s sheets-sheet 2
:Suventor _
@QL 29,1946.
Filed May 6, 1944
5 Sheets-Sheet 5
_èn Mmvsßm
Patented Oct. 29, 1946
Robert H. Baker, Munster, Ind.
Application May 6, 1944, Serial No. 534,447
2 Claims. (Cl. 62-1)
The present invention relates to improvements
ice cubes and the like and to a novel method of
of heating unit mounted in a tube indicated in
broken lines.
Figure 5 is a View similar to Figure 1 showing a
defrosting the freezing unit, ice cube trays, ice
modified form of heating unit and its yapplica
in defrosters for freezing units, ice cube trays,
tion t0 a refrigerating unit of the refrigerator.
Figure 6 is a plan view of a further modified
form of heating unit.
Figure '7 is a longitudinal section therethrough
taken on the line 'l-l in Figure 6.
` An object of the invention is> to provide one or
Figure 8 is a perspective View of the interior
more forms of simple andrinexpensive heating 10
members of such heating unit.
units which lend themselves readily to applica
lFigure'9 is an exploded view of the elements or
tion to the freezing unit of an electric or other re
members of this group.
frigerator in a position or positions where such
Figure 10 is a modified form of heating ele
heating unit, when activated, will melt or defrost
ment showing a three-member group.
the area in the Vicinity ,ofl the tray and its sup
Figure 1l is an exploded view of the three
port so as `to permit the tray to be readily de
cubes, etc., and more particularly relates to a
heating element and the method of use of such
element in refrigerators for the quick defrosting
and easy removal of ice cube trays and ice cubes.
tached from the side walls of the freezing unit,
from the shelf .upon which itrests and from its
contact with adjacent trays, if any.
Another object of the invention is to suit the
heating unit to the freezing unit with a minimum
of reconstruction of the latter.
A further object of the invention is to so con
struct, constitute and arrange one or more heat
ing units at opposite local positions in the freez
ing unit as to be effective for local defrosting in
a minimum of time.
`Figure `12 is a longitudinal section taken
through a `container with the threeV element
Figure '13 shows a further modified form of the
heating element and an insulator support there
Figure 14 shows the case for this form of
heating unit.
Figure 15 is a fragmentary sectional view
through a showcase type of store refrigerator _
having one of the improved defrosting elements
applied thereto in connection with a metallic
thermostat for automatically interrupting the 30 radiating sheet.
circuit through the heating resistance wire after
Figure 16 is a perspective view showing a dia
the lapse of a >predetermined time period to avoid
grammatic preferred coil arrangement of the re
destructive action of the heat upon the refrig
sistance heating wire with two terminals for
erant or the refrigerating unit and its parts.
convenience in plugging into a socket.
The invention further contemplates a form of 35
Referring more particularly to the drawings
heating unit and radiating sheet in a new rela
and for the present to Figures 1, 2 and 3, 2i)
tionship to the refrigerant tubes and thermo
designates the freezing unit of a conventional
stat in a showcase type of >store refrigerator.
form usually found in household refrigerators in
With the foregoing and other objects in view,
which a rectangular metallic frame 2l is exter
the invention will be more fully described here 40 nally surrounded by refrigerant coils 22. With
inafter, and will be more particularly pointed out
in the frame 2l the usual trays for the ice cubes
in the claims appended hereto.
may be introduced in a well known manner and
In the drawings, wherein like symbols refer to
supported either upon the bottom 23 of the frame
like or corresponding parts throughout the sev
or upon a shelf 24 or both.
The invention also‘contemplates the use of a
Figure -1 is a perspective view of a -refrig
ating unit of a conventional type showing the
application of one form of the improved heating
In accordance with the present invention one
or more heating units are applied to either the
bottom 23, side walls of the frame `2"! or to the
shelf 24 or to all of these parts as shown in Fig
units thereto.
ure 1.
eral views,
Figure 2 is Ya horizontal section taken on the 50
line 2-2 of Figure 1.
Figure 3 is a perspective view, with parts broken
For this purpose the said bottom 23, shaft 24
and Side walls of the frame 2| are pressed out
wardly along definitive lines to produce grooves
25 in which the heating elements may be placed.
ÁOne such heating unit is shown in Figure 3 as
Figure 4 is a perspective view of a modified type 55. Comprising an electric resistance wire 26 em
away and parts shown in section, of one form of
heating unit employed.
through the perforations from one to the other
bedded in a body of insulation 21 and encased
side of the sheet 36. In other words it is threaded
through the perforations. The sheets are held
between blocks of insulating material 38.
Referring more particularly to Figures 6 to 9
resistance wire 26 running axially through the
inclusive, a still further modified form of heating
tube and Wrapped with spun glass electrical tape
element is shown consisting of four sheets of
which proved satisfactory for insulating the
mica 36, 46, 4|, 42. An intermediate sheet 4| is
heating element from the copper tube. In the
reduced between its ends to receive the resistance
first instance the heating wire 26 was wrapped
with the glass tape and thereupon inserted into 10 wire coil 43. One end of the coil passes out
through a perforation 44 of a companion sheet 46
the copper tube 2B while this tube extended in
in a copper or other metal tube 28.
A satisfactory form of heating unit has con
sisted of a 1A" copper tube 28 with the heating
a straight line.
and is thus brought out as one of the leads 45 of
Before any current was turned
the element.
into the wire 2‘6 the unit comprising Wire 26
wrapped tape 21 and copper tube 28 was bent
to the desired curves and shapes. Thereupon the
heating wire 26 was charged and the glass tape
caused to fuse slightly which caused it to lose
some of its pliability without sacrificing its ideal
insulating qualities. The fusion caused the tape
after several hours of continuous heat to con
solidate into a cohesive and homogeneous in
sulating body 21 tending to unit wire 26 and tube
28. The spun glass tape, so fused, has qualities
for lasting indefinitely. It is not desired to
charge the element with electricity until the tube
28 has been bent to the desired shape.
As hereinafter described more particularly in
connection with Figure 15, the circuit of the
heating wire 26 may be controlled by a thermo
stat, or the wire 26 may be of predetermined
resistance so that it heats to the desired tem
perature and will not rise destructively above
The other lead 46 comes off the
other end of the coil 43. The sheets 35 and 42
15 form enclosing members for the two intermediate
sheets 46 and 4|. All four sheets can be very
readily enclosed in a metal case composed of the
half parts 41 and 48 with the ends 49 clipped to
gether as shown in Figure 7. This element can
20 be very easily installed in present day refrigera
tors and can be manufactured at very moderate
cost. Two such elements would be sufficient, one
under each ice tray, or placed at the sides of the
Referring more particularly to Figures 10, l1
and 12, a very similar form of heating unit is
illustrated having the three sheets 5U, 5| and 52
to make a still thinner unit in which sheets 56 and
52 are blank or imperforate and all are of mica
30 or suitable insulating material. The intermediate
sheet 5I is perforated as indicated at 53 to receive
the resistance wire 54 which is run therethrough
in the manner indicated in Figure 10. These
the same.
three elements, in the order named are assembled
When current is turned through the wire 26 the
ice trays, although frozen tight, will be loose 35 into a metallic case 55 as shown in Figure l2.
in a matter of a few minutes.
It may take some
what longer to free the ice cubes.
After de
energizing the heating unit, the freezing unit
Referring more particularly to Figures 13 and
14, 56 designates a sheet or plate of insulating ma
terial having perforated insulators thereon which
support the coiled heating wire 58. This element
will reestablish its freezing temperature in ap
proximately ten minutes. The refrigerator can 40 is received into a metal case 59 with the mica
sheet 56 acting as the cover for the case to en
be defrosted while the door of the refrigerator
close the heating unit.
is closed. The switch element should be de
Referring more particularly to Figure l5 this
signed so as to shut off the freezing unit when
is a cross section of the freezing unit of a show
the defroster is in use. The element 26 should
not be allowed to get too hot as this might be 45 case type of store refrigerator. The freezing unit
usually runs all the way across the front of the
come harmful. 1n larger refrigeration units,
refrigerator although in some types there vis a
Where the cost would not be prohibitive an elec
freezing coil at each end of the showcase. The
trical clock or timer could be used that would
heating unit is of the type illustrated in Figure 3
automatically defrost the unit at the necessary
50 and is designated generally at 28a. On account of
its versatility this unit may be made to follow the
Referring more particularly to Figure 4 a
freezing unit regardless of type or shape.
modified form of the heating unit comprises a
The heating element 23a generates heat for de*
porcelain or other insulating solid core 29 with a
frosting purposes. Its copper tube is in contact
helix 36 of electric resistance wire wound eX
ternally about the same and through V-shaped 55 with the metallic sheet 66 which absorbs the heat,
confines and distributes the heat directly to the
notches 3| in discs 32 of porcelain or other in- '
refrigerant tubes or coils 6|. Heat from the ele
sulating material which are fitted about the core
ment 28a radiates through the sheet 66 to the re
2'8 at the ends and suitable intervals therealong.
frigerant tubes 6| and thermostat 62 at approxi
The discs are of greater diameter than the core
26 thus providing protected areas between the 60 mately the same ratio, making it possible to con
trol the amount of heat which reaches the re
discs 32 for containing the wire 30. Further
frigerant tubes 6 I. It would not be necessary for
protection is obtained by the tubular shaped
the heat to reach a temperature of over 60 or ’70
cover 33 which may be of copper similar to the
degrees. A drainage trough 63 is seated beneath
cylinder 28 of Figure 3. A metal material for
l the heating unit 28a, distributing plate 60 and
the parts 28 and 33 is desirable on account of
coils 6l' to carry off to a suitable vessel for easy
the high conductivity of the metal which tends
removal the Water resulting from the defrosting
to transfer and distribute the heat generated
from within the heating unit to the areas to be
The flat heating elements such as shown in
Figures 6 to 12 inclusive can be manufactured
Referring more particularly to Figure 5 the
very cheaply and can be usedk in every conceivable>
bottom, side walls and shelf of the freezing unit
type of refrigerating unit without requiring any
are compartmental as indicated at 34 and 35
alterations whatsoever. It would simply raise the
to receive heating units composed of sheets 36
pan a quarter of an inch.
of mica prepared to receive therethrough the
1n the claims wherever the word “wire” is used
high resistance Wire 31. This> Wire is passed 75
it will be understood that it refers not only to a.
wire but also to a coil, rod, bar or strip of material
that generates heat.
It is obvious that various changes and modi
ñcations may be made in the details of construc
tion and design of the above specifically described
embodiment of this invention without departing
from the spirit thereof, such changes and modi
fications being restricted only` by the scope of the
following claims,
What is claimed is:
1. A modiñed refrigerating evaporator for
household refrigerators in which refrigerating
coils surround a rectangular metallic frame hav
ing side walls, a bottom, a top and being without
ends to admit slidable trays for ice cubes, the
modification comprising pressed-out areas in the
walls and bottom along deñnitive lines to produce
grooves opening on the inner space of the unit,
and heating coils lying in said grooves flush with
the plane of the inner faces of the wall and upper
face of the bottom.
2. The combination of claim 1 characterized by
the fact that the heating coils are formed of tubes
of metal having straight pieces of resistance Wire
axially therethrough and wrapped with spun
glass electrical tape fused throughout into a co
hesive and homogeneous insulating mass between
the wire and tube.
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