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Oct. 29, 1946.
Filed May 15, 1942
F! G. ‘2.-.
‘2 Sheets-Sheet l
Emu. K. CLAzK
Oct‘ 29, 1946.
Filed May 15, 1942
2 Sheets-Sheet 2
Patented Oct. 29, 1946
Earl K. Clark, Mans?eld, Ohio, assignor to West
inghouse Electric Corporation, East Pittsburgh,
Pa., a corporation of Pennsylvania
Application May 15, 1942, Serial No. 443,032
1 Claim. (Cl. 219-20)
This invention relates to a control for an elec
vention as will be apparent from the following de
scription and claim taken in connection with the
accompanying drawings, forming a part of this
application, in which:
Fig. 1 is a perspective view of an electric cook
ing range in which the present invention is em
tric heating unit, such asthe surface unit of an
electric range, and it has for an object to provide
an improved control.
The control commonly used comprises a switch
actuated by a rotary knob and having an “off”
position, a position of maximum heat, and sev
eral positions of reduced heat. To initiate a cook
Fig. 2 is a fragmentary vertical section taken
ing operation, the knob is rotated from the “off”
approximately along line II—l_I of Fig. 1, showing
position to one of the heat positions, and to ter 10 one of the surface units and the control arrange
minate the cooking operation the knob is rotated
ment therefor;
to the “off” position. The knob may also be
Fig. 3 is a View similar to Fig. 2 except that
shifted from one heat position to another during
parts are omitted for clarity of illustration, with
the cooking operation. This type of control is
a cooking utensil positioned On the heating unit
generally satisfactory but it has certain limita 15 and showing the relationship of the parts of the
tions or disadvantages. One of these is that the
control arrangement when the heating unit is
current may be turned on regardless of whether
connected to a power source; and,
there is a cooking utensil or other article to be
‘Fig. 4 is a fragmentary vertical section of a
heated on the heating unit, thereby permitting a
range similar to that shown in Fig. 1 but incor
waste of electric current. Also, the user may re 20 porating a modi?ed form of the invention.
move the cooking utensil from the heating unit
Figs. 1, 2 and 3
and forget to turn the switch to the “o ”_ po
drawings in detail, I show an
sition, thereby resulting in a waste of electric cur
electric range In which comprises three surface
rent. A further disadvantage is that, each time
a. cooking operation is initiated or terminated, it 25 heating units I9, 20 and 2| and a deep well cooker
22. The unit 20 is provided with a control incor
is necessary to effect rotary movement of the
porating the present invention. Any one or all of
knob and to note the position to which the knob
the units l9 and 20 and the cooker 22 may be pro
is actuated; whereas, the easiest control opera
vided with a similar control. Other than the
tion is one wherein a control element is moved
more or less in a straight line to the end of its 30 novel control referred to, the range In may be of
travel, such as pushing a button.
It is an object of the present invention to pro- ‘
vide a control for a heating unit whereby a com
conventional construction.
The time clock l4
controls the oven in a well-known manner.
Referring to Figs. 2 and 3, the heating unit 20
comprises a single armored resistance element 25
single actuation of a control member, such as 35 which is spirally coiled to provide a ?at grid. The
7 ends of the resistance element 25 are provided
pushing a button.
with terminals indicated schematically at 26 and
A further object is to provide a control includ
21, for connecting the heating element to a suit
ing a control element which may be adjusted to
able source of power. This grid is mounted on
provide varying degrees of heat, and which need
not be reset to terminate the cooking operation. 40 supporting arms 28 which rest on the shoulder 33
Another object is to provide a control includ- , _ of a re?ector pan 30, which in turn is supported
on the range platform l2. The heating unit is
ing a control element which may be adjusted to
adapted to support a cooking utensil placed there
provide varying degrees of heat, and which need
plete cooking operation may be carried out by a
not be reset to terminate the cooking operation,
on to be heated, as shown at I I2 in Fig. 3. A cas
nor to initiate a subsequent cooking operation if 45 ing or hollow button 36 extends through the cen
the same degree of heat is desired.
ter of the heating unit and the re?ector pan 30.
It is vertically movable and is biased upwardly by
A further object is to provide a control where
a spring 40 to a position in which it projects above
in the supply of current to the surface unit is
the plane of the top of the heating unit.
controlled by the placing of a cooking utensil or
The heating unit 20 may be energized from a
the like on the surface unit, but wherein provision 50
is made for guarding against unintended supply
suitable source of power, such as the line con
of current to the surface unit when placing a
cooking utensil or other article thereon for stor
age purposes only.
., These and other objects are effected by the in 55
ductors L1 and L2. The control for controlling
the supply of current from the line conductors
to the heating unit 20 comprises a line switch 45,
a wattage controller 86, and a thermostatic
switch 85. The line switch includes a push but
ton 5|. It completes a connection to the line
conductors L1 and L2 when a cooking utensil or
the like is placed on the heating unit 20 and the
button 9i is pushed in, and it opens the connec
tion when the vessel is removed from the heating
unit 20. The wattage controller 96 controls the
average wattage input or rate of energization of
the heating unit. In the present embodiment,
by the oversize opening 18, and is latched in back
in which the heating unit comprises a single 10
of the hook 82 as shown in Fig. 3. The switch
55 is now latched in closed position and will re
main closed as long as the utensil remains on the
heating unit. When it is removed, the spring 89
moves the lever Tl in clockwise direction to re
lease the member ‘ill and permit the resilient
member 53 to return to the open switch position
shown in Fig. 2.
The wattage controller 86 is located in back of
the backsplasher l3 and includes a thermostatic
or bimetal element 92 fixed at its lower end to
a stationary dielectric member 93. At its other
ing the circuit to the heating unit and it is ad
end, the bimetal element 92 is adapted to move
justable to vary the ratio of the “on” period to
the “oiT” period to provide diiferent rates of ener 15 into and out of engagement with a stationary
contact 96. The wattage controller further in~
gization, and to a continuous "on” position and
cludes a small or auxiliary heating element 98
preferably also to a continuous “off” position.
adapted to heat the bimetal element 92, which
The thermostatic switch 85 supersedes the watt
moves to the left out of engagement with the
age controller 89 during "the initial period of a
cooking operation to provide continuous current 20 contact 95 as its temperature is raised by the
heating element. To make the Wattage controller
or maximum rate of energization until the utensil
adjustable, the contact 96 is adapted to be moved
placed on the heating unit is brought to the boil
toward or away from the bimetal element 92 by
ing temperature. The wattage controller 86 and
means of a knob 91 disposed on the front of the
the thermostatic switch 85 are in accordance with
the invention of Edward Bletz, described and 25 backsplasher £3. The knob may, for example, be
mounted on a screw 95 threaded through the
claimed in his application, Serial No. LlOGjlSl.
heating element, the wattage controller effects
such control by intermittently opening and clos
backsplasher and abutting the contact 96, the
The novelty of the present invention resides par
latter being movably mounted in a suitable man~
ticularly in the line switch 45 and in its combina~
nor as will be readily understood by one skilled
tion with the wattage controller and the thermo~
static switch. These three parts of the control 30 in the art.
The heating element 90 and the bimetal ele
will now be described in greater detail.
ment 92 are connected in series in the circuit
The line switch 45 includes contacts 41 and 49
through the heating element 25. This circuit ex
connected to the line conductors L1 and L2 and
tends from line conductor L1, through the switch
insulatedly mounted on a resilient member 53
contacts Ill and 59, the conductor [52, the ter
through a dielectric member 54. It further in
minal 27, the heating element 25, the terminal
cludes a pair of cooperating contacts 49 and 50
26, the conductor 155, the heating element 99, the
adapted to be connected to the respective termi
bimetal element 92, the contact 96, the conductor
nals 26 and 21 and insulatedly mounted on a
I54, and the switch contacts 49 and 48 to the line
resilient member 56 through a dielectric member
51. The upper ends of the members 53 and 56 40 conductor L2. As current ?ows through the cir
cuit, the temperature of the bimetal element 92
are attached to the opposite sides of a stationary
member 59.
The push button 6| is mounted on the outer
end of a stem 62 which extends through the
front wall of the range in alignment with the
resilient member 59, so that by pushing the but
ton 5| the resilient member 53 is moved to bring
its contacts in engagement with the cooperating
contacts to close the switch. The stem 62 is
is raised by the heat from the heating element
90 and as it reaches a temperature determined by
the setting of the knob 91, it deflects to the left
out of engagement with the contact 96, thereby
opening said circuit. The flow of heat from the
heating element 90 is thus terminated and as the
bimetal element 92 cools to the predetermined
temperature, it moves into engagement with the
attached to the upper end of a member ‘H1 which 0 contact 95, thereby reestablishing the circuit. The
heating element 90 again heats the element 92
is pivoted at its lower end to a stationary block 13.
and the cycle of “on” and “o?” periods is re
The line switch 45 is provided with a mecha
nism for latching it in closed position when it is
By turning the knob 9'! to move the contact 95
closed while there is a utensil on the heating
unit 20. This mechanism includes a lever TI 55 to the left, the ratio of “on” period to “off” period
is increased since more heat is required to de?ect
pivoted on a stationary fulcrum by means of
the element 92 further to the left. Accordingly,
an oversize opening 18 in the lever and a pin 19
the average wattage input to the heating unit
which extends through the opening 18. A spring
and its rate of heat delivery to the utensil is in
80 biases the lever in clockwise direction. The
creased. The contact 96 may be moved sui
right-hand end of the lever l“! extends through
?ciently to the left to remain in engagement with
a slot 15 in the member 19 and is formed with
bimetal element 92, thereby providing a position
an upwardly-extending hook 82 which is adapted
of continuous energization or maximum heating.
to engage a struck-out portion 83 of the member
By moving the contact 99 to the right, the ratio
19 to hold the switch in closed position. The
left-hand end of the lever 11 has an angular 65 of the “on” period to the “oil” period is de
creased, since less heat is required to move the
portion 84 thereon which bears against the bot
bimetal element 92 out of engagement with the
tom. of the hollow button 36.
contact 96, and it is preferably movable su?lcient~
When a utensil is placed on the heating unit,
ly to the right to be out of engagement with the
the button 35 is depressed and the lever Tl is
tilted counter-clockwise to the position shown in 70 bimetal element 92 at room temperature, thereby
providing a completely “off” position.
Fig. 3. This operation conditions the control for
The pilot thermostat 85 is located‘in the upper
closing the circuit but does not in itself close the
‘ portion of the hollow button 36 so as to be in
circuit. If the button 6| is now pushed in to
close proximity to the bottom of a cooking utensil
close the switch, the struck-out portion 83- rides
over the inclined surface 8|, which is permitted 75 placed on the heating unit 20. This thermostat
includes a pair'of contacts“ and 88 and a-bi
metal snap-acting element 89 having a pair of
contacts thereon which normally bridge the con
tacts 81 and 88. The thermostatic switch 85 is
connected, by means of a conductor I53, in shunt
with the conductor I55 and the heating element
98. Accordingly, when the thermostatic switch
' is closed, the current is shunted therethrough and
on the’shoulder I84 of a reflector pan I83, the
latter being again supported on the platform of
the range. A pin I85 extends vertically through
the center of the heating unit and is biased up
wardly by a compression spring II8, the upper
end of which engages a pressure plate I89 which
in turn bears against a shoulder on the pin I85.
The ends of the two resistance elements are pro
vided with terminals represented schematically
the heating element 88 is deenergized, thereby
maintaining the bimetal element continuously in lo by the reference characters 88 to I8I for con
necting the heating unit to a suitable source of
engagement with the contact 96.
Figs. 1, 2 and 3.—Operation
The heating unit 28 may be energized from a
To initiate a cooking operation, the user ?rst
suitable source of power, such as an Edison three
places the utensil M2 on the heating unit 28, 15 wire system including two outside conductors L1
which action tilts the lever ‘I1 into counter
and L2 and a neutral conductor N. A switch I I4
clockwise direction, in which position it is
is provided for connecting the resistance elements
adapted to latch the member ‘I8. The user then
I33 and I34 to the line conductors in a manner
pushes the button 6| to close the line switch 45,
well known in the art to give a plurality of di?er
which is thereby latched in closed position by 20 ent heats; for example, to connect the heating
.the engagement of the member 18 with the lever
elements in parallel across the conductors L1 and
11. Assuming that the wattage controller 86 has
L2 to give a high heat, to connect one of them
been left at a setting which is still suitable, this
across the same conductors to give a medium high
pushing of the button is the only control op
heat, to connect both of them in series across the
eration necessary to be effected by the user for
same conductors to give a medium heat, to con
the entire cooking operation.
nect one of them across the conductors L1 and N
Since the temperature of the utensil I I2 is nor
to give a low heat and to connect both of them in
mally below the boiling temperature at the be
series across the conductors L1 and N to ‘give a
ginning of a cooking operation, the thermostatic
simmer heat. The switch II4 may be of a con
switch 85 remains closed. Accordingly, the heat 30 struction already well known in the art, so that
ing element 98 of the wattage controller is
further description thereof is not necessary. This
shunted and does not heat. Accordingly, the
switch is mounted on the back of the backsplasher
?ow of current through the heating unit is con
tinuous and delivers heat at its maximum rate
to the utensil II2‘.to raise its temperature as
quickly as possible to the boiling point. When
the boiling point is reached, the thermostatic
switch opens its contacts, causing the current to
?ow through the heating element 98. The watt
I3, but may be disposed elsewhere. It includes a
knob H5 provided on the front of the back
splasher for setting the switch to obtain the dif
ferent degrees of heat specified above.
The switch H4‘ is connected to the conductors
L1, L2, and N through conductors IIB, I28 and
H9, respectively. Conductors I23, I24 and I26
age controller 86 thereby assumes control of the 40 connect the switch I I 4 to the terminal 98, the two
heating unit in accordance with the setting to
terminals 99 ‘and I 88 in common, and the ter
which it has previously been adjusted. Such
minal I8 I , respectively.
setting will normally provide a relatively low
A two-pole switch I38‘ and a two-pole switch
rate of energization such as that known. as sim
I3I are interposed in the conductors H8 and
mering. Such heating continues until the user
I28, so that if either of these switches is open,
lifts the utensil from the heating unit, at which
the heating unit cannot be energized. The switch
time the lever 11 is tilted in clockwise direction to
I38 is actuated by the pin I85, described above,
unlatch the member ‘I8. Due to the resilience of
and is closed when the pin is depressed. The
the member 53, the line switch 45 thereupon
switch I3I includes a rod I 45 on which the con
opens the connection to the line conductors L1
50 tact-bridging elements are mounted. Its forward
and L2 to terminate all supply of heat.
end extends through the backsplasher and a push
It will thus be apparent that it is not necessary
button I46 is mounted or formed thereon. It is
to turn the knob 91 to the “off” position at the
biased to open circuit position by a spring I48
end of a cooking operation, nor is it necessary to
acting through a pressure plate I41. A solenoid
adjust it to the desired heating position every ,
time that a cooking operation is initiated. The
including a core I58 mounted on the rod I45 and
a coil I5I is adapted when energized to hold the
same setting of the wattage controller 86 will be
switch I3I in closed position. The coil I5I is
found satisfactory for most cooking operations,
energized by a circuit I53 controlled by its own
so that the knob 91 may be left in the same posi
tion from one cooking operation to another and
Figure 4.—Operation
adjusted only when an unusual cooking opera
tion is encountered. This means that, for most
The operation of the embodiment shown in
cooking operations, the only control operation
Fig. 4 is as follows: The cooking utensil or the
necessary for the user to carry out is to push
like to be heated is positioned on the heating unit
the button 6|.
28a, thereby closing the switch I38. The circuit
Figure 4
is still open, however, at the switch I3 I. The user
then pushes the button I48 to close the switch
Referring now to Fig. 4, I show an embodiment
I3I. The circuit is now completed to the switch
in which electrical mechanism instead of a me
II4, thereby placing the latter in control of the
chanical latch is employed for retaining a line
energization of the heating unit 28a. If the switch
switch in closed position only so long as there is a
knob I I5 is already in a heat position, then ener
utensil positioned on the heating unit. In this
gization of the heating unit 28a is effected upon
embodiment, the heating unit 28a comprises two
armored resistance elements I33 and I34 which
closing of the switch I3I at the rate determined
are spirally coiled to provide a grid mounted on
by the position of the knob II5. If it is in the
supporting arms I36. The ends of the latter rest 75 “o?” position, then the heating unit is not ener
gized until “such time as the knob is moved to a
heat position. It may be noted that the knob I I5
may be turned at any time, but that the switch
II4 can be effective to energize the heating unit
only at such time as both switches I30 and I3I u
are closed.
unit. Upon placing a utensil on the heating
unit, however, pushing the button I46 would
complete the holding circuit and the switch I3I
would be held in closed position until the utensil
is removed from the heating unit.
The singlev claim is directed to the embodi
Upon completing the cooking operation, the
ment shown in Fig. 4.
user merely lifts the utensil from the heating
What is claimed is:
unit. This opens the switch I30 to interrupt the
The combination with an electrical heating
supply of electric current to the heating unit. 10 unit adapted to supply heat to a cooking utensil
Since the holding circuit for the solenoid I53 is
or the like and a source of power for said heating
also deenergized by such current interruption,
unit, of a switch for connecting said heating unit
the switch I3I is opened by the spring I48. Ac
to said power source, said switch being biased to
cordingly, the circuit cannot be reestablished
open position, means for moving said switch to
until such time as both of the switches I30 and
closed position, electro-magnetic means for hold
I3I are again closed by placing a utensil on the
heating unit and pushing the button I46, respec
tively. In terminatingthe cooking operation, it
ing said switch in closed position, a circuit con
necting said electro-magnetic means to said
power source for energizing the same, said circuit
being so arranged that it is open at all times that
position, but it may be left undisturbed until such
said switch is open, a second switch connected in
time as it is desired to energize the heating unit
said circuit, said second switch being moved to
at a different rate than that for which the knob
closed position by placing a cooking utensil or
is set. In other words, where the same degree
the like on said heating element, thereby com
of heat is desired, the knob may be left in one
pleting the circuit from said power source to said
position from one cooking operation to another
electro-magnetic means and making the same
and only actuated when a diiferent degree of heat
effective to hold said ?rst switch in closed posi
is desired.
tion when moved to such position, said second
Instead of having the pin I05 controlling the
switch being biased so as to move to open-cir
switch interposed in the conductors H6 and I20,
it may actuate a switch in the holding circuit for 30 cuit position when there is no cooking utensil or
the like on said heating unit thereby opening the
the coil I5 I. In such case, the heating unit could
circuit from said power source to said electro
be energized without placing a utensil thereon by
magnetic means and rendering said electro-mag
merely pushing the button I46, but it would be
netic means ineffective to hold said ?rst switch
energized only so long as the button is manually
in closed position when there is no cooking utensil
held in the closed circuit position. As soon the
or the like on said heating unit.
button I46 is released, the spring I48 would re
open the switch I3I to deenergize the heating
is not necessary to turn the knob I I5 to the “off”
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