Jan. 4, 1949.
E, CHALLET
SOLID ELEGTRIC_HEATING PLATE
Filed Oct. 28, 1957‘
. '
2,458,251
Patented Jan. 4, 1949
UNITED
2,458,251
STATES i PATENT " OFFICE
2,458,251
SOLID vELECTRIC HEATING PLATE
Etienne Challet, Paris, France, assignor to Entre
prises Electriques Fribourgeoises, Fribourg,
" ' Switzerland, a company of Switzerland
Application October 28, 1937, Serial No. 171,576
In Switzerland January 13, 1937
Section 3, Public Law 690, August 8, 1946
Patent expires January 13, 1957
3 Claims.
1
The present invention relates to electrically
heated plates.
(Cl. 219-37)
2
may be of round, annular, or of any other desired
shape.
If a solid plate of the same thickness through
Referring to the drawings wherein similar ref
out is heated uniformly it will ?rst become red
erence characters denote like parts in the vari
in a zone which is concentric to the periphery of
ous views Fig. 1 illustrates a partial sectional
the plate and which divides the plate surface into
view of a solid round plate. The plate is indi
two zones of substantially equal area. Then as
cated at I and the heating element 2 therefore
the heating is continued the red zone will spread
is located as shown in a conventional insulating
towards the periphery and towards the center
unit. As is clearly shown upon Fig. 1 the dis
of the plate. However the ?rst mentioned zone 10 tance between the top of each insulating unit and
is generally the hottest. It is an object of the
the upper surface of the plate varies for each in
invention to provide means whereby the heating
sulating unit. In the zone wherein there is the
is uniform throughout the entire plate.
maximum concentration of heat this length is
On the other hand if the heating of the plate
indicated by the distance line between the ar
is discontinued the plate will ?rst cool at the 15 rows 3. This length gradually decreases towards
periphery and at the center and the concentric
the periphery and towards the center where it
central zone remains red even after the other
reaches
the length shown by the distance lines
parts of the plate have regained their normal
4 and 5.
appearance. It is an object of the invention to
By constructing the thickness of the metal of
provide a plate wherein cooling will take place
the
plate proportional to the quantity of heat
uniformly from the peripheries toward the central
transmitted
by the resistance to the plate at each
zone.
point a uniform heating of the entire plate may
An object of the invention therefore is to pro
be obtained.
vide an electrically heated plate wherein the
In Fig. 2 a modi?cation is shown wherein 6
stresses and strains due to heating are eliminat 25 indicates
the plate, 1 the heating element and
ed thereby considerably increasing the life of
the distances of the heating elements from the
the plate.
surface of the plate is shown by the distance lines
A still further object of the invention is to pro
8, 9 and I 0.
vide an electrically heated plate wherein the
In this form of construction the central por
thickness of the plate along the zone of great 30
tion of the plate is provided with an undulating
est heat concentration is increased and such in
section integral with the plate. This construc
creased thickness takes place gradually from the
tion at the central portion will yield to any con
periphery and the center of the plate to the above
tractions or expansions of the plate itself.
mentioned Zone of greatest heat concentration.
I claim:
A further object of the invention is to provide
1. An integral electrically heated plate com
35
a solid electrically heated plate in which the
prising heating units and an integral metallic
thickness of the metal is proportioned to the
plate supporting said units, said plate having a
quantity of heat transmitted by the heating
thickness gradually increasing from the pe
unit at each point of the plate. In this way the
riphery inwardly and from the center outwardly
surface portion of the plate subject to the great
est concentration of heat will be heated uni
formly with the periphery and the center of the
plate thereby eliminating any strain at the pe
ripheral and central portions and also prevent
towards a concentric zone intermediate said pe
riphery and center so that a uniform heating
throughout said plate may take place.
2. An integral electrically heated plate com
prising heating units and an integral annular
ing warping.
With the above and other objects in view which 45 metallic plate supporting said units, said plate
having a thickness gradually increasing from the
will become apparent from the detailed descrip
periphery inwardly and from the center out
tion below the invention is shown in the draw
wardly towards a concentric zone intermediate
Fig. l is a partial cross-sectional view through , said periphery and center so that a uniform heat
’ ing throughout said plate may take place.
one form of an electrically heated plate con
ings in which:
structed in accordance with the invention.
Fig 2 is a similar View of another type of elec
trically heated plate.
In the invention the electrically heated plate
3. An integral electrically heated plate com
prising heating units and an integral metallic
plate of disc shape supporting said units, said
units being arranged annularly between a cen
tral portion of said plate and the periphery
2,458,251
3
4
thereof, said plate having a thickness gradually
REFERENCES CITED
increasing from the periphery thereof inwardly
and from said central portion outwardly towards
n
a concentric zone intermediate said periphery
n
-
'
and central portion so that a uniform heating 5
throughout said plate adjacent said heating units
-
?ghgf ffhigwggferll‘sere ces are of record ‘m the
UNITED STATES PATENTS
Number
Name
Date
may take place and said plate having at said
central portion an undulating con?guration
whereby any contraction or expansion of said
plate may be compensated for without any stress 10
1,435,153
1,492,540
1579332
1,729,673
Wolcott __________ __ 15131126, 1924
Kercher et a1 ______ __ Apr_29,1924
Owen _____________ __ Apr_ 6, 1926
Kercher et a1 _______ __ Oct 1, 1929
01‘ 8min-
1,998,764
2,015,856
Jordan ___________ __ Apr. 23, 1935
Lang ______________ __ Oct. 1,1935
ETIENNE CHALLET'