Euro-Pro Exhibit 1007
`Euro-Pro Exhibit 1006
`Euro-Pro v. Acorne
`Euro-Pro v. Acorne
`Page 1 of 11
`IPR2014-00186
`IPR2014-00186
`Page 1 of 11
`Page 1 of 11
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`

`
`3311- 22. 1957
`
`B. J. VALLORANI
`
`CONTROL CIRCUITS FOR ELECTRIC OVENS
`
`Filed Oct. 22, 1954
`
`2,778,914
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`3311- 22, 1957
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`B. J. VALLORANI
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`
`CONTROL CIRCUITS FOR ELECTRIC OVENS
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`United States Patent Ofice
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`2,778,914
`Patented Jan. 22, 1957
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` 2
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`1
`2,778,914
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`CONTROL CIRCUITS FOR ELECTRIC OVENS
`
`lien J, Vallorani, River Forest, Ill., assignor to General
`Electric Company, a corporation of New York
`
`Application October 22, 1954, Serial No. 463,957
`10 Claims.
`(Cl. 219—20)
`invention relates to control circuits for
`The present
`electric ovens, and more particularly to improved control
`circuits for such ovens provided in electric ranges of the
`home appliance type.
`In a conventional electric range of the home appliance
`type, there is provided at least one oven comprising upper
`and lower electric heating elements, a three-wire Edison
`source of electric current supply, a manually operable
`control switch selectively operative to establish different
`electrical heating connections between the heating ele-
`ments and‘ the source of current supply so as selectively
`to set the oven to carry out different ‘nroiling and halting
`operations, a manually settable thermostatic switch re-
`sponsive to the temperature in the oven for selectively
`completing and interrupting the established heating con-
`nections upon a temperature basis in the baking opera-
`tions of the oven, and a timer switch for selectively
`cornpleting and interrupting the established heating con-
`nections upon a clock-time basis in the baking operations
`of the oven.
`ln such an oven, the thermostatic switch
`alternately closes and opens completely the established
`heating connections upon a ternperature basis in the baking
`operations, whereby there is :1 considerable amplitude of
`the temperature variation in the oven cavity and also sub-
`stantial departure between the amplitude of the tempera-
`ture variation of the oven cavity and that of the thermal
`element of the thermostatic switch operatively associated
`with the oven cavity. Not only are these characteristics
`objectionable from the standpoints of efficiency and uni-
`formity of operation of the oven, but they are responsi-
`ble for the objectionable condition of “too much radia-
`tion eifect” normally present in the upper portions of
`such conventional ovens. This condition is also referred
`to as “too much top heat” in oven operation and is ex-
`ceedingly objectionable in cake-baking operations as it
`leads directly to lack of uniformity of texture and mois-
`ture content in the resulting product.
`Accordingly, it is a general object of the invention to
`provide in an electric oven of the character described, an
`improved and exceedingly simple control circuit that min-
`imizes the amplitude of temperature variation in the oven
`cavity and substantially eliminates any departure between
`the amplitude of the temperature variation of the oven
`cavity and that of the thermal element of the thermo-
`static switch operatively associated with the oven cavity,
`whereby the oven is admirably suited to cake-baking
`operations.
`Another object of the invention is to provide an im-
`proved control circuit for an electric oven of the char-
`acter described, wherein the thermostatic switch is of
`exceedingly simple construction and arrangement and
`achieves the improved operating characteristics noted by
`selectively completing and interrupting a plurality of dif-
`ferent heating circuits including the heating elements of
`the oven in the respective cold and hot positions thereof,
`so that in the hot position of the thermostatic switch heat
`is still supplied to the oven cavity, but at a lower rate than
`when the thermostatic switch is in the cold position
`thereof.
`
`A further object of the invention is to provide an im-
`proved control circuit for an electric oven of the charac-
`ter desciibed, wherein an increased number of different
`heating circuits for the heating elements is achieved with-
`
`out an increase in the number of heating elements em-
`ployed, but rather by a higher degree of selectivity of en-
`ergization of a standard number of heating elements
`across the various lines of the associated three-wire Edison
`supply source, whereby a higher degree of utilization of
`the standard number of heating elements is made than in
`a conventional electric oven.
`A still further object of the invention is to provide in
`an electric oven of the character described, an improved
`control circuit, wherein the operating conditions de-
`scribed are achieved not only in manually controlled bak-
`ing operations, but also in automatic clock-controlled
`baiting operations.
`Further feattlres of the invention pertain to the partic-
`ular arrangement of the elements of the circuit control
`network, whereby the above-outlined and additional oper-
`ating features thereof are attained.
`The invention, both as to its organization and method
`of operation,
`together with further objects and advan-
`tages thereof will best be understood by reference to the
`following specification taken in connection with the ac-
`companying drawings, in which:
`Figure l is a fragmentary front view of the upper por-
`tion of an electric range incorporating a broiling and
`baking oven control circuit embodying the present in-
`vention;
`2 is a diagram of the circuit control network in-
`corporated in the range shown in Fig. 1, all of the switches
`and circuit controls being illustrated in their normal or
`off positions;
`Fig. 3 is a 'fragmei1tary portion of the diagram shown
`in Fig. 2,
`illustrating the circuit connections when the
`manual control switch occupies its broil position;
`Fig. 4 is another fragmentary portion of the diagram
`shown in Fig. 2, illustrating the circuit connections when
`the manual control switch occupies its regular bake po-
`sition;
`Fig. 5 is a further fragmentary portion of the dia-
`gram shown in Fig. 2, illustrating the circuit connections
`when the manual control switch occupies its time bake
`position;
`Fig. 6 is a diagram of a modified form of the circuit
`control network that may be incorporated in the range
`shown in Fig. 1, all of the switches and circuit controls
`benig illustrated in their normal or oil positions;
`Fig. 7 is a fragmentary portion of the diagram shown
`in Fig. 6,
`illustrating the circuit connections when the
`manual control switch occupies its broil position;
`Fig. 8 is another fragmentzuy portion of the diagram
`shown in Fig. 6, illustrating the circuit connections when
`the manual control switch occupies its regular bake
`position;
`Fig. 9 is a further fragmentary portion of the diagram
`shown in Fig. 6, illustrating the circuit connections when
`the manual control switch occupies its time bake posi-
`tion;
`‘Fig. 10 is a diagram of another modified form of the
`circuit control network that may be incorporated in the
`range shown in Fig. 1, all of the switches and circuit con-
`trols being illustrated in their normal or off positions;
`‘Fig. 11 is a fragmentary portion of the diagram shown
`in Fig. 10, illustrating the circuit connections when the
`manual control switch occupies its broil position;
`Fig. 12 is another fragmentary portion of the diagram
`shown in Fig. 10, illustrating the circuit connections when
`the manual control switch occupies its regular bake po-
`sition; and
`Fig. 13 is a further fragmentary portion of the dia-
`gram shown in Fig. 10, illustrating the circuit connec-
`tions when the manual control switch occupies its time
`Page 5 of 11
`bake position.
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`In the diagrams of Figs. 2 to 5, inclusive, and 10 to
`13,
`inclusive, the control circuits embody manually op-
`erable control switches of the pushbutton type; and in
`the diagrams of Figs.» 6 to 9, inclusive, the modified form
`of the control circuit embodies a manually operable con-
`trol switch of the rotary snap type.
`In the diagrams of
`theheating elements appearing in Figs. 2 to 6, inclusive,
`a broken line indicates that
`the corresponding heating
`element is deenergized, and a solid line indicates that the
`corresponding heating element is energized.
`Referring now to Fig.
`1 of the drawings, the electric
`range 10 there illustrated and incorporating the broil-
`ing and baking oven control embodying the features of
`the present invention comprises an upstanding metal body
`11 that is provided with a cooking top 12 terminating in
`an upwardly -directed backsplash 13. A broiling and bak-
`ing oven cavity 14 is defined in the upper right-hand por-
`tion of the body 11 by a metal oven liner, not shown,
`which oven cavity 14 is provided with a door 15 that
`is hinged adjacent to the lower edge thereof and movable
`between open and closed positions.
`In the upper por-
`tion of the oven cavity 14, a first removable frame, not
`shown,
`is provided that supports first and second elec-
`tric heating elements 16 and 17 in a substantially hori-
`zontal and coplanar position and in inner and outer re-
`lation with respect to each other; and in the lower por-
`tion of the oven cavity 14, a second removable frame,
`not shown, is provided that supports a third electric heat-
`ing element 18 in a substantially horizontal position. The
`heating elements 16, 17 and 18 may be the open resist-
`ance coil
`type and are arranged upon the respective
`upper and lower frames in the general manner disclosed
`in U. S. Patent No. 2,498,583, granted on February 21,
`1950,
`to Herman W. Schulze,
`the electric heating ele-
`ments being suitably electrically insulated from the asso-
`ciated supporting frames.
`The circuit network that is provided for the purpose
`of selectively controlling the electric heating elements 16,
`17 and 18 comprises a manual control switch 19 mounted
`upon the backsplash 13 that is preferably of the push-
`button type and of the general construction disclosed in
`U S. Patent No. 2,431,904, granted on December 2,
`1947,‘to John L. Andrews. Specifically the control switch
`19 of the pushbutton type includes four individual manti-
`ally operable pushbuttons respectively corresponding to
`the off,‘ broil,
`regular bake" and time bake positions
`thereof.
`In passing,» it is noted that the control switch
`19 ‘is so constructed andarranged that as any one of
`its pushbuttons is manually actuated into its in position,
`the last-actuated one of its pushbuttons is returned to
`its out position, and the control switch is set into its
`control position corresponding to the presently actuated
`one of its pushbuttons. Also the backsplash 13 carries
`a thermostatic switch 24? that is provided with a manu-
`ally operable control dial 21, as well as a timer switch
`22 that is provided with a clock face 23, a manually set-
`table on knob 24 and a manually settable off knob 25.
`‘Further the backsplash 13 carries a thermostatic switch
`pilot
`lamp 26,21 control switch pilot lamp 2'7, and a
`number of other pushbutton switches 28 for controlling
`the surface units, not shown, that are also carried by the
`cooking top 12.
`Referring now more particularly to Fig. 2 of the draw-
`ings,
`it is pointed out that the thermostatic switch 20
`further comprises a thermal responsive element 3% ar-
`ranged Within the oven cavity 14 and responsive to the
`temperature therein, as well as a connecting capillary tube
`31. The thermostatic switch 20 is of the single-pole
`single-throw type including the single contact bridging
`member 32.
`It will be understood that the thermostatic
`switch 20 may be selectively set
`to maintain any pre-
`determined. temperature Within the oven cavity 14 by
`proper,-manipul_ation.of -thecontrol dial 21. Specifically,
`in the. thermostatic. switch .20, the bridging member 32
`normally bridges or closes the associated pair of contacts
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`and is operated to open the associated pair of contacts
`in response to an influence upon the thermal responsive
`element 3% indicating that the temperature Within the
`oven cavity 14 has reached the temperature previously
`set. by the control dial 21.
`Preferably the timer switch 22 is of the general con-
`struction of that disclosed in U. S. Patent No. 1,522,988,
`granted on‘ January 13, 1925, to Henry E. Warren, and
`comprises a synchronous electricmotor 39 of the “Tele-
`chron” type, as well. as a pair of Contact bridging mem-
`bers -4-1 and 52. The bridging members <31 and 42 nor-
`mally occupy open positions with respect to the asso-
`ciated pairs of contacts, and are later operated into closed
`positions with respect to the associated pairs of contacts,
`at a first preset clock time governed by the on control
`knob 12-4, and are still
`later operated back into their
`open positions with respect to the associated pairs of
`contacts, at a second preset clock time governed by the
`off control knob 2.5. For example, in the timer switch
`22, the on control knob 24 may. be set to a first prede-
`termined clock time, such, for example, as 5 o’clock,
`and the off control knob 25 may be set to a second pre-
`determined clock time, such, for example, as 6 o’clock;
`whereby the timer switch 22 effects the selective controls
`noted of the bridging members 41 and 42 at the two
`previously set clock times so that a baking operation is
`carried out
`in a manner more fully explained herein-
`after in the oven cavity 14- from 5 o’clock to 6 o’clock.
`The manual control switch 19 of the pushbutton type
`further comprises five incoming terminals 51, 52, 53, 54
`and 55, five outgoing terminals 51, 62, 63, 64 and 65,
`and five individual switch blades 71, 72, 73,
`'74 and '75,
`as best shown in Figs. 3, 4 and 5. The individual switch
`blades 71, etc. are adapted to complete connections be-
`tween the corresponding individual
`incoming terminals
`51, etc., and the corresponding individual outgoing termi-
`nals 61, etc.,
`in the different positions of the control
`switch 19, as explained more fully hereinafter. Also in
`the control switch 19,
`the incoming terminals 51 and
`52 are permanently strapped, the incoming terminals 53
`and 54 are permanently strapped, and the outgoing termi-
`nals 64 and 65 are permanently strapped.
`Further, the circuit network comprises a bus 81 com-
`monly connecting together the inside terminals of the
`heating elements 1d, 17 and 18, a bus 82 terminated by
`the outgoing terminal 61, a bus 83 terminated by the out-
`going terminal 62, a bus 84 terminated by the outgoing
`terminal 63 and connected to the outside terminal of the
`heating element 16, a bus 85 commonly terminated by
`the outgoing terminals 64 and 65 and connected to the
`outside terminal of the heating element 18, and a bus
`87 terminated by the incoming terminal 55. Further,
`the circuit network comprises a three-wire Edison source
`of current supply of 236 volts, single-phase A. C. that
`includes first and second outside lines 91 and 92 and a
`grounded neutral line 93. The outside line 91 is corn-
`mouly connected to the incoming terminals 51 and 52;
`the outside line 92 is commonly connected to the in-
`coming terminals 53 and 54; and the neutral line ‘)3 is
`connected to the outside terminal of the heating element
`17. The contacts controlled by the bridging member 32
`are respectively connected to the busses 31 and 33; the
`contacts controlled by the bridging member 41 are respec-
`tively connected to the busses 83 and 82; and the contacts
`controlled by the bridging member 42 are respectively
`connected to the bus 37 and the outside line 92. The
`winding of the electric motor 39 is connected across the
`outside line 92 and the neutral line 93; the thermostatic
`switch pilot
`lamp 26 is ‘connected across the neutral
`line 93 and the bus 81; and the control switch pilot lamp
`27 is connected across the neutral line 93 and the bus 82.
`In the arrangement: the heating element 16 may have
`a resistance of 1.7.4 ohms, developing awattage of 3200
`watts-at 236 volts;
`the heating element 17‘may have in
`resistance of 17.4 ohms, developing a wattage of 800
`Page 6 of 11
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`2,778,914
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`watts at 118 volts; the heating element 18 may have a
`resistance of 18.6 ohms, developing a wattage of 3000
`watts at 236 volts.
`Considering now the operation of the circuit control
`network of Figs. 2 to 5,
`inclusive, in conjunction with
`the control of the heating elements 16, 17 and 18, it is
`noted that when the off pushbutton of the control switch
`19 is actuated, the five incoming terminals 51 to -55, in-
`clusive, are respectively disconnected from the five out-
`going terminals 61 to 65, inclusive, as indicated in Fig. 2;
`whereby the heating elements 16, 17 and 13 are de-
`energized, as shown in broken lines in Fig. 2. Also at
`this time it may be assumed that the oven cavity 14 is
`cold so that the thermostatic switch 20 operates the bridg-
`ing member 32 to close the associated pair of contacts.
`Further, it may be assumed that the timer switch 22 is
`operating for clock purposes, but
`that neither of
`the
`control knobs 24- or 25 is set. At this time, the thermo-
`static switch pilot lamp 27 and the control switch pilot
`lamp 28 are extinguished.
`Now assuming that the cook wishes to perform a broil-
`ing operation, she merely operates the broil pushbutton
`of the control switch 19 setting the circuit elements into
`the condition shown in Fig. 3; whereby the incoming
`terminals 51, 52 and 53 are respectively connected to
`the outgoing terminals 61, 62 and 63 by the respective
`switch blades ‘/1, 72 and 73. When the control switch
`19 is thus operated into its broil position, the heating
`element 16 is energized across the outside lines 91 and
`92 via a circuit including the busses 83, 81 and 84, as
`well as the bridging member 32; and the heating element
`17 is energized across the outside line 91 and the neutral
`line 93 via a circuit including the busses .83 and 81, as
`well as the bridging member 32. Accordingly, the heat-
`ing element 16 develops its full rated wattage of approxi-
`mately 3200 watts; and the heating element 17 develops
`its full rated wattage of approximately 800 watts. Thus
`in the broil position of the control switch 19, the total
`4000 watts is developed in the upper portion of the oven
`cavity 14, which is desirable for broiling purposes.
`Normally when a broiling operation is to be carried
`out in the oven cavity 14, the control dial 21 of the
`thermostatic switch 20 is set up to its maximum tem-
`perature position and the door 15 is set ajar or cracked
`to ventilate the oven cavity 14; whereby the thermostatic
`switch 20 ordinarily exercises no control during the broil-
`ing operation. Also at this time the thermostatic switch
`pilot lamp 26 is illuminated between the bus 81 and the
`neutral line 93 in order to indicate that the bridging mem-
`ber 32 of the thermostatic switch 20 occupies its closed
`position with respect to the associated pair of contacts;
`and the control switch pilot lamp 27 is illuminated be-
`tween the neutral line 93 and the bus 82 in order to
`indicate that the control switch 19 occupies other than
`its off position.
`the cook wishes to perform a
`Now assuming that
`regular baking operation, she first sets the control dial 231
`to the temperature that is desired in the oven cavity 14,
`and merely operates the regular bake pushbutton of the
`control switch 19 setting the circuit elements into the
`condition shown in Fig. 4; whereby the incoming termi-
`nals 51, 52 and 54 are respectively connected to the out-
`going terminals 61, 62 and 64 by the respective switch
`blades 71, 72 and 74. When the control switch 19 is
`thus operated into its regular bake position, the heating
`element 18 is energized across the outside lines 91 and
`92 via the busses S3, 81 and 85 and the contact bridging
`member 32 of the thermostatic switch 20; and the heating
`element 17 is energized across the outside lines 91 and
`the neutral line 93 via the busses 83 and 81 and the
`contact bridging member 32 of the thermostatic switch 20.
`Accordingly, the heating element 18 develops its full rated
`wattage of approximately 3000 watts; while the heating
`element 17 develops its full rated wattage of approxi-
`mately 800 watts. Thus in the regular bake position
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`of the control switch 19, when the contact bridging mem-
`ber 32 is closed, the total wattage developed in the oven
`cavity 14 is approximately 3800 watts; however, about
`3000 watts of this total wattage is developed by the heat-
`ing element 18 so that a disproportionate amount of
`heat is produced in the lower portion of the oven cavity
`14, which is necessary in order that a substantially uni-
`form distribution of the heat be effected throughout the
`oven cavity 14, which is desirable for regular baking
`purposes.
`During the carrying out of the regular baking opera-
`tion in the oven cavity 14-, when the temperature therein
`reaches the temperature previously set by the control dial
`21 of the thermostatic switch 2.0, the temperature respon-
`sive element 30 is suitably influenced in order to govern
`the thermostatic switch 20 so that the bridging member
`32 is operated to open the above-traced primary parallel
`circuits for energizing the heating elements 17 and 18,
`whereby the heating elements 17 and 18 are energized
`in series relation across the outside line 92 and the
`neutral line 93 via the busses
`and 81. Accordingly,
`the heating element 17 develops only a small wattage
`of approximately 185 watts and the heating element 18
`develops only a small wattage of approximately 200
`watts. Thus in the regular bake position of the control
`switch 19, when the Contact bridging member 32 is open,
`the total wattage developed in the oven cavity 14 is ap-
`proximately 385 watts; however, about 200 watts of this
`total wattage is developed by the heating element 18 so
`that a disproportionate amount of heat is produced in
`the lower portion of the oven cavity 14, which is neces-
`sary in order that a substantially uniform retention of the
`heat be effected throughout the oven cavity 14-, which is
`desirable for regular baking purposes.
`The temperature within the oven cavity 14 gradually
`subsides, and when it reaches a temperature slightly be-
`low that previously set by the control dial 21 of the
`thermostatic switch 20, the temperature responsive ele-
`ment 30 is suitably influenced in order to govern the
`thermostatic switch 20 so that the bridging member 32
`is operated to interrupt the above—traced secondary series
`circuit for energizing the heating elements 17 and 18
`and to reclose the above-traced primary parallel circuits
`for energizing the heating elements 17 and 18. As the
`regular baking operation is continued, the thermostatic
`switch 20 operates in the manner described above to hold
`the previously set
`temperature in the oven cavity 14.
`During the regular baking operation the thermostatic
`switch pilot lamp 25 is illuminated only when the bridg-
`ing member 32 of the thermostatic switch 20 occupies
`its closed position with respect to the associated pair of
`contacts, producing a corresponding indication; and the
`control switch pilot lamp 27 is illuminated in order to
`indicate that the control switch 19 occupies other than
`its off position.
`the cook wishes to perform a
`Finally assuming that
`time baking operation, she first sets the control dial 21
`to the temperature that is desired in the oven cavity 14,
`and then sets the time during which tie time baking
`operation is desired upon the timer switch 22.
`Spe-
`cifically, the on control knob 24 is set at the clock-time
`it is wished to initiate the baking operation, such, for
`example, as 5:00 o’clocl;; and the 01? control knob 25
`is set to the clock-time at which it is wished to arrest
`the baking operation, such, for example, as 6:00 o’clocl;.
`Then the cook operates the time bake pushbutton of the
`control switch 19 setting the circuit elements into the
`condition shown in Fig. 5 ; whereby the incoming terminals
`51 and 55 are respectively connected to the outgoing
`terminals 61 and 65 by the respective switch blades 71
`and 75.
`‘When the control switch 19 is thus operated
`into its time bake position, a circuit is prepared for ener-
`gizing the heating element 18 across the outside lines
`91 and 92, which circuit is open at this time at the two
`’ contact bridging members 41 and 42 of the timer switch
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`22; and a circuit is prepared for energizing the heating
`element 17 across the outside line 91 and the neutral line
`93, which circuit is open at this time at the contact bridg-
`ing member 41 of the timer switch 22.
`Thus at this time while the timer switch 22 occupies
`its open position, there is no potential upon the heating
`elements 16, 17 and 18; and accordingly,
`there is no
`shock hazard to the cook should she inadvertently touch
`any one of the heating elements 16, 17 or 18 while she
`is also in contact with the metal liner of the oven cavity
`14 or the metal body 11 of the range 10. This consider-
`ation is of fundamental importance only with respect to
`the upper heating elements 16 and 17 that are exposed
`directly in the top of the oven cavity 14, since the heat
`distributing shield or baffie normally associated with the
`lower heating element 18 in the bottom of the oven
`cavity 14 prevents contact by the cook with the lower
`heating element 18.
`In other words, the shock hazard
`mentioned is really with respect to the upper heating ele-
`ments 16 and 17; which shock hazard is prevented in the
`present arrangement.
`Continuing now with the time baking operation, when
`the clock 23 of the timer switch 22 reaches the 5:00
`o’clock position set by the on control knob 24, the bridg-
`ing members 11-1 and 42 are operated into their closed
`positions with respect to the associated pairs or" contacts
`completing the circuits for energizing the heating ele-
`ments 17 and 18. The circuit for energizing the heating
`element 17 extends from the outside line 91 via the switch
`blade 71,
`the bus 82, the contact bridging member 41,
`the bus 83, the contact bridging member 32, the bus 81
`and die heating element 17 to the neutral line 93; while
`the circuit for energizing the heating element 18 extends
`from the outside line 91 via the switch blade 71, the bus
`82,
`the contact bridging member 41,
`the bus 83,
`the
`contact bridging member 41,
`the bus 832,
`the contact
`bridging member 32, the bus 81, the heating element 18,
`the bus 85,
`the switch blade 75,
`the bus 87 and the
`contact bridging member 42 to the outside line 92.
`Accordingly, at this time the heating elements 17 and 18
`respectively develop the full rated wattages of approxi-
`mately 925 watts and approximately 2000 watts previously
`mentioned in conjunction with the regular baking oper--
`ation.
`The time baking operation proceeds in a manner iden-
`tical to that of the regular baking operation previously
`described, under the control of the thermostatic switch
`20 and until the clock 23 reaches the 6:00 o'clock posi-
`tion set by the off control knob 25; whereupon the con-
`tact bridging members 41 and 42 are operated back into
`their normal open positions with respect to the associated
`pairs of contacts,
`thereby interrupting the previously
`traced circuits for energizing the heating elements 17 and
`18. Again it will be observed that when the contact
`bridging members 41 and 42 of the timer switch 22 are
`returned into their open positions with respect
`to the
`associated pairs of contacts, all potentials are removed
`from the heating elements 1-6, 17 and 18 in order again
`to eliminate any shock hazard to the cook should she
`inadvertently touch any one of
`the heating elements
`noted while she is also in contact with the metal liner
`of the oven cavity 14. At this time,
`the time baking
`operation has been completed.
`In the time baking opera-
`tion the control of the therrnostatic switch pilot lamp Z6
`and the control of the control switch pilot lamp 27 are
`the same as described in conjunction with the regular
`baking operation.
`-
`Referring now to Figs. 6 to 9, inclusive, of the draw-
`ings,
`the modified form of the control circuit for the
`electric range 10 there illustrated and embodying the
`features of the present invention is substantially identical
`to the control circuit
`therefor previously described in
`conjunction with Figs. 2 to 5, inclusive, except that the
`manually operable control switch 119 is of the rotary
`snap type instead of the pushbutton type.
`Specifically,
`
`10
`
`15
`
`20
`
`25
`
`30
`
`40
`
`45
`
`50
`
`60
`
`70
`
`75
`
`8
`in Fig. 6, it will be understood that in the oven cavity
`114 the arrangement and disposition of the heating ele-
`ments 116, 117 and 118 are substantially the same as those
`previously described; and the thermostatic switch 120,
`and its elements, as well as the timer switch 122, and its
`elements, are the same as previously described. More-
`over, in the control circuit of Fig. 6, the arrangement of
`the three-wire Edison source of current supply including
`the outside lines 191 and 192 and the grounded neutral
`line 193 is the same as that previously described.
`control
`More particularly,
`the manually operable
`switch 119 of the rotary snap type is preferably of the
`general construction and arrangement of that disclosed
`in U. S. Patent No. 2,203,236, granted on June 4, 1940,
`to Charles P. Randolph et al.; and, of course, it will be
`understood that the control switch 119 is mounted upon
`the backsplash 13 of the electric range 10 in the usual
`manner.
`Specifically,
`the control switch 119 of
`the
`rotary snap type includes a single rotary operating knob
`119a manually operable into corresponding ofr”, broil,
`regular bake and time bake positions, the control switch
`119 including six incoming terminals 151 to 156, inclu-
`sive, six outgoing terminals 161 to 166,
`inclusive, and
`six individual switch blades 171 to 176, inclusive, as best
`shown in Figs. 7, 8 and 9. The individual switch blades
`171, etc., are adapted to complete connections between
`the corresponding individual
`incoming terminals 151,
`etc., and the corresponding individual outgoing termi-
`nals 161, etc., in the difierent positions of the control
`switch 119, as explained more fully hereinafter.
`In the
`control switch 119, the incoming terminals 151 and 152
`are permanently strapped,
`the incoming terminals 153
`and 155 and the outgoing terminal 166 are permanently
`strapped together,
`the outgoing terminals 162 and 163
`are permanently strapped, and the outgoing terminals
`164 and 165 are permanently strapped. When the con-
`trol switch 119 occupies its off position the incoming
`terminals 153 and 155 are respectively connected to the
`outgoing terminals 163 and 165 by the respective switch
`blades 173 and 175, as illustrated in Fig. 6; when the
`control switch 119 occupies its broil position,
`the in-
`coming terminals 152, 155 and 156 are respectively con-
`nected to-the outgoing terminals 162, 165, and 166 by
`the respective switch blades 172, 175 and 176, as illus-
`trated in Fig. 7; when the control switch 119 occupies
`its regular bake position,
`the incoming terminals 151,
`153, 155 and 156 are respectively connected to the out-
`going terminals 161, 163, 165 and 166 by the respective
`switch blades 171, 173, 175 and 176, as illustrated in
`Fig. 8; and when the control switch 119 occupies its
`time bake position, the incoming terminals 151, 153 and
`154 are respectively connected to the outgoing terminals
`161, 163, 164 by the respective switch blades 171, 173
`and 174, as illustrated in Fig. 9.
`As illustrated in Fig. 6,
`the inside terminals of the
`heating elements 116 and 117 are commonly connected
`to a bus 181; the outside terminals of the heating ele-
`ments 116 and 117 are respectively connected to a bus
`182 and to the neutral line 193; and the inside and out-
`side terminals of the heating element 118 are respec-
`tively connected to two busses 184 and 185. The com-
`monly connected incoming terminals 151 and 152 are
`connected to the outside line conductor 192;
`the com-
`monly connected incoming terminals 153 and 155 and
`the outgoing terminal 166 are connected to the bus 132;
`the incoming terminal 154 is connected to a bus 186;
`the incoming terminal 156 is connected to a bus 187;
`the outgoin