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Dw- >1 7,1945- J. R. GoMERsALL ' ET AL 2,412,727 AUTOMATIC ELECTRIC TOÀSTER COMPENSATOR FOR VARIABLE VOLTAGE CURRENT SUPPLY " Filed Feb. 16’, 1942 - 2 Sheets-Shee'b l 3 J7 6/ ‘tv’ v (2.3) .1r ///// ///////////ï F’ ' /Íf _,Á) ’ INVENToRs. -MUHRA Y/RELAND BY »vz/MM ATTORNEY ' Dm 17» 194.5 J. R. _GoMERsALL Erm. AUTCMATIC ELECTRIC TOASTER COMPENSATOR FOR VARIABLE VOLTAGE CURRENT SUPPLY Filed Feb. 1s, 1942 2,412,727 :ay sheets-sheetvz ATTORNEY Patented Dec. 17, i945 2,412,727 UNITED STATES `P’A'I’EN'I‘ OFFICE 2,412,727 AUTOMATIC ELECTRIC 'JTÍOASTERv COMPEN SATOR FOR VARIAB RENT SUPPLY LE VOLTAGE CUR John n. Gomersali; Elgin, and Murray Ireland, near Elgin, Ill., assignors- to McGraw Electric Company, Elgint Ill-.,»a corporation of Delaware Application February 16, 1942,'¿Serial No.V 431,088 1 5 Claims. Our invention relatesl to electric cooking de vices and particularly to automatic elect'ricï toasters. An object ci our invention is'to provide means applicable to an automatic electric toaster which will compensate for the e?ïect of a variable voltage current supply energizing the toast heating ele (Cl. 219-19) 2 toaster assembly Il which comprises a moulded skeleton frame i3 and an outside casing l5 which in general are of the type which have been made and soldv heretofore. The outside casing l5 has an open upper end portion in which there islo cated atop closure member ll which, as shown ments. more particularly in Fig~ 3 of the drawings, is provided` with a bread-slice inserting and toast Another object of our invention is to provide removing opening is, in a- manner now well an automatic electric toaster that may be con nected to energizing circuits of appreciably dif 10 known in the art. The toaster assembly is pro vided further with a relatively thin sheet metal ferent voltages and which will provide substan bottom plate 2l` suitably secured against the up tially the same degree oi toasting for different per surface of the frame i3 and the bottom edge slices of bread. portions of the casing I5 may be secured either Another object of our invention is to provide a new method for toasting slices of bread compris 15 against the bottom plate 2l or the moulded base ing the steps of limiting the maximum tempera i3 as may be found desirable or suitable. Qur toaster assembly includes further a pair of spaced'vertically extending planar toast heat ing elements 23 and 2d which may be held in their the heat for a preset and iixed length of time. _ Another object of our invention is to provide 20 proper operative positions within the casing by any suitable or desired means not pertinent to relatively simple means which will ensure that, ture of the heat applied to the slice or slices of bread and subjecting the bread to the action of for a given setting of the control elements of an automatic electric toaster, substantially the same amount of heat from the toast heating elements will reach or aii‘ect the slice or slices of bread being toasted, irrespective of the voltage of the supply circuit to which the toast heating ele ments are connected. Other objects of our' invention Will either be apparent from a description of one form embody ing our invention or will be pointed out in the course of such description and set forth in the appended claims. In the drawings: Figure 1 is a longitudinal vertical sectional View through a toaster embodying our invention, Fig. 2 is a horizontal sectional View on the line 2-2 oi’ Fig. l, nor constituting a part of our invention. in order to properly center a slice of bread while it is toasting in a vertical position between he toast heating elements and 25 We provide guard or guide wires 2l the lower ends of‘which may ex tend through the base plate 2l and the upper re turn-bent end portions may be supported by lon gitudinally extending topirame plates 29 or inv any other suitable or desired manner. A strand of resistance conductor 3l may be wound on rel atively thin sheets of electric insulating material, such as mica, which constitute a part of the toast heating elements 23 and 25. We provide further bread carriers 33 extend ing substantially horizontally between the spaced toast heating elements and the iront end of such bread carrier may be rigidly connected with a Fig. 3 is a vertical sectional View taken on the 40 ?lrstfcarriage- Süß-of substantially L-shape, whichy carriage-ìs--provided at its upper and at its lower ends with guide-bushings 3l adapted to move ver Fig. 4 is a vertical sectional view taken on the line 3_3 of Fig. l, line 4-4 of Fig. l, Fig. 5 is a diagram of the electrical connections showing the position of the contacts while-still at lower temperature, and, Fig. 6 is a diagram of the electrical circuits showing the parts of Fig. 5 after having been heated to a given temperature. We have elected to show our invention and 50 particularly the novel elements thereof as applied to a single-slice automatic electric toaster but it is to be understood that our invention may bev applied to other types of toasters. We have illustrated an automatic electricl 55 The tically lower reciprocally end'of thison standard a vertical may standard be supported by the base plate 2| while the upper end thereof may be supported» by a small bracket lil, all in a manner well known in the art. We provide further a second reciprocally mov able carriageßê, which second carriage is pro vided with upper and lower bearing bushings 45 which are adapted to move on the vertical stand ard 3d; We provide a main switch for the toast heating elements,` which switch comprises a pair of con tact‘- members 41 insulatedly supported in proper operative'position on the base plate 2l near its 2,412,727 3 4 operator, such as “medium,” for example will i front edge portion. Carriage 35 is adapted to support a contact bridging member t9 insulated , cause successive slices of bread of the same kind to receive substantially the same browning or degree of toasting as long as the temperature of the toaster remains at the same value. ly secured to a resilient member 5l which mem ber 5i is carried by and moves with the first men tioned carriage 35. When the carriage 35 is In case, however, the energizing supply circuit moved to its lowermost position, contact bridging voltage is much lower, a similar slice of bread member li@ will engage the contact members d1 to thereby close an energizing circuit through the toast heating elements, it being assumed, of course, that .the toast heating elements are elec trically connected by means of a twin conductor would be toasted only to the light degree and, therefore, the operator would have to change the setting of the timing mechanism to lengthen the toasting operation and thereby obtain the desired medium degree of toasting. If medium toast was desired and had been ob cord 53 with a suitable source of supply of elec tric energy. tained in a toaster operated on a 115 volt cir cuit and which was then connected to a 125 volt The bread carrier is normally yieldingly biased to an upper non-toasting position by means of a tension coil spring 55 one end of which is con circuit, the degree of toasting would probably be that usually called “dark” .if indeed it might not nected to carrier 33 or carriage 35 While the other be black or burnt. end thereof may be connected to bracket 4 I. It is to be noted further that the ñrst slice of The second carriage plate 43 is provided with bread to be toasted, starting with a cold toaster, 20 a forwardly-extending portion 5'1 which is of will not be as dark or as well toasted as will, say, such length as to extend outwardly beyond the the third, fourth or ñfth slice of toast when the front portion of the casing i5 is through a slot toaster is operated with but small time intervals, 59 therein and an actuating knob 3l is secured to on the order of say five seconds between the suc the arm 5l so that an operator may press down wardly on knob 6I to cause downward movement cessive toasting operations. A number of different inventions have been made .and applied to toasters of .the various kinds of carriage d3, carriage 35, and the bread carrier when it is desired to move the bread carrier into now on sale which effect what is usually called a compensation for not only the variation of the its lowermost toasting position. ' We provide also a suitable timing mechanism eifect of the different temperatures under which 63 here shown as including a spring-driven train a toaster will operate because of quickly succes sive operations, but also to take care of the fact that different toasters assembled and tested in .the factory at a selected standard voltage, may be operated at much lower or much higher volt of gears of the general kind shown in Ireland Patent No. 1,866,808 but it is to be understood that any other timer which will operate for an adjustably preset i'lxed length of time may be used in place of such mechanical timer. An ad justing knob Se may be provided, by which the operating period of the timer may be manually varied. The timer mechanism E3 is held in proper >operative position by a bracket 65. The .timer is provided with a lever detent mem ber 51 pivotally mounted on the timing mecha ages by different purchasers of similar toasters made by the same manufacturer. Thus, if it be assumed that one toaster may operate on a 100 volt supply circuit at one time and may operate 40 on a 125 volt supply circuit at another time, it is evident that the amount of energy translated into heat at .the higher voltage is over fifty pre nism 33 near the lower end of the lever and an cent greater than that translated into heat at end portion E9 is provided on the lever 61 at its the lower voltage. The parts now ~to be described lower end which portion 55 is adapted to be en and constituting more particularly our inven gaged by a laterally projecting portion ‘il con tion provide compensating means which may be stituting a part of or secured to the ñrst carriage considered to be 100% effective to take care of 35. Thus when carriage 35 is moved downward variations in the temperature of .the toaster as lY, as hereinbefore described, it Will engage the well as taking care of different supply circuit portion e9 and be held in its lowered position, that voltages. 50 is, with the carrier in its toasting position for We provide a bimetal member “i5 which in the such length of time as may be determined by .the present embodiment is preferably made of sub operation of the timing mechanism 63. stantially U-shape and is connected in electric The timing mechanism E3, when it is of the series circuit with the toast heating elements 23 type disclosed in Patent No. 1,866,808, will be and 25. We prefer to mount the compensating 55 wound up when carriage member 43 is moved bimetal strip or bar 'i5 out of close thermal com downwardly and the construction is such that the munication with the body of the toaster and par carriage member 43 will be moved upwardly with ticularly of the toast heating elements and the returning part of the mechanical timer as therefore locate it below the base plate 2i which clearly described in the above mentioned patent 60 is provided with a Ventilating opening îî imme and when a release portion 'I3 on carriage 43 en gages a roller l5 mounted on the upper end of lever (il, latch member ‘H will be released from detent lever 61 and the spring 55 will cause quick upward movement of the carrier into its non toasting position. The parts of the toaster hereinbefore described are those which constitute a standard toaster, large numbers of which have been made and sold and it is to be understood that the timing mech anism 63 has mounted thereon means permit ting of varying its time of operation so that light, medium or dark toast may be obtained and as long as the toast heating elements are subjected to substantially the same energizing supply cir cuit voltage, say 115 volts, any one setting by an diately above the bar 15 so that air will be drawn inwardly through a properly perforated crumb tray 19, past the bimetal bar 'i5 and through the opening or openings 11 in the base plate 2l, 65 vertically upwardly past the toast heating ele ments and out through the opening is. . W e provide further a secondary toast heating element control switch including a spring bar 8l connected in series electric circuit with the bimetal bar l5 and the toast heating elements 23 and 25, this bar 8| having a contact member 83 at its free end. A second contact member 85 is mounted on an auxiliary current traversed bimetal bar 3i for a purpose which will hereinafter appear. The free end of the bimetal bar 'l5 is provided with an 5 2,412,727 adjustable short machine screw 3Q which is adapted to engage a small lug di of electric in sulating material mounted on spring b r Si near the contact member t3. The diagrams oi connection shown Figs. 5 and 6 disclose the connections oi the toast heating elements, the bimetal bars d? and the auxiliary switch just above described. The design 6 heating elements will be substantially the same as was supplied to the toast heating elements when connected to a 105 volt circuit. If now a light piece of toast is desired, the timer will be mandati adjusted by the operator to reduce the length oi a toasting operation, but the same gen eral comments made hereinbefore as to dark toast will apply. and construction of the bimetal bar is such One of the results of our new method of toasting that when heated it will move in a counter-clock 10 _is that instead of what may be called purely “sur wise direction as seen in Fig. 2 of the drawings, face toasting” being effected, a slice of bread is and will cause set screw to engage lug @i on the toasted deeper and the inside of the slice of bread spring Contact bar Si at a given temperature to is baked out or dried out to some extent. thereby cause opening of the heating circuit oi the Our new method of operation as obtained by toast heating elements. It has been found that in a structure of this general 1sind, contact me i ers S3 an are the use of a toaster embodying our invention results the intermittent application of toasting heat, and particularly radiant heat to the sur faces of a slice of bread, the temperature of this heat being definitely limited because of the fact caused to engage each other and to be disengaged from each other at relati ely very short intervals, giving rise to radio interference, and we therefore 20 that as soon as this temperature and the tempera prefer to provide some means for causing a greater ture of bimetal bar 'i5 reaches a given value, the difference ci temperature to occur as to bimetal current is interrupted. As noted above, the past bar 'i5 before operation ci the secondary switch method has been to use a variable time or length is effected. We may use the secondary bimetal of a toasting period and not to limit the tempera bar 3l which is so designed and constructed that ture and our invention provides a new method, it will move in a clockwise direction, as seen in namely that of a limited maximum temperature Fig. 2 of the drawings, when subjected to tempera and an invariable or fixed length of time of toast ture rise. The eiîect or result ci” the action of ing operation irrespective of supply circuit volt the secondary bimetal bar is to cause disengage age and the temperature of the toaster structure. ment of contact members E3 and to be effected It may be further pointed out that when a 30 only after an appreciable change oi temperature toaster of the kind embodying our invention is of bimetal bar '55 and this change temperature used on a relatively low voltage energizing circuit, can be made to have any desired value. the length of the current-on periods will be sub We have found by actual tests on compensated stantially greater than the length of time of the toasters of this kind that the operation a toaster current-off periods but, of course, this condition embodying our invention results in substantially will change when the toaster is operated on a cir the same amount oi" heat energy reaching or cuit of higher voltage. aiïecting a slice of bread, for a given setting of the However, the main distinguishing element of timing mechanism such as medium, irrespective our toaster' and its method of operation is that of the temperature of the toaster because of close- ,I ly successive toasting operations or because of L., we provide means which will ensure that a sub stantially presetl amount of heat reaches a slice connection to different supply circuit voltages. or slices of bread being toasted irrespective of The bimetal bar oí course, effective, since the temperature of the toaster and particularly it is traversed by a current either the saine as or of its toasting chamber and irrespective also of proportional to that traversing the toast heating the voltage of the supply circuit to which the elements, to limit the temperature to which the toast heating elements may be connected. surfaces of a slice of bread `eing toasted are sub Various modifications and changes may be jected. .t is Íurther evident that the adjustment made in the structure embodying our invention and setting or” the control parts must be that‘ and al1 such changes clearly coming Within the which will give the desired degree oi toasting on scope of the appended claims are to be considered the lowest supply circuit voltage which be as being covered thereby. used to energize the toast heating elements an W e claim as our invention: that, therefore, a slice of bread toasted i a toaster l. In an automatic electric toaster adapted for of the kind embodying our invention will be sub operation on electric circuits of diiîerent voltages jected to a longer toastinLT operation period than and comprising toast heating elements, a main would otherwise be necessary where individual ad switch for said heating elements, means to start justments of the timer might be made to adapt a toasting operation, a constant speed timer star* the toaster to say greatly differing’ supply circuit ed running in response to said starting means to voltages. time the toasting period and operative to cause Thus, if a dark piece of toast is desired on a low opening of said main switch and terminate a voltage supply circuit (say 105 volts), 'the setting toasting operation after a preset ñXed length of of the timer will be such as to give a relatively time, a second switch for controlling the ener long toasting operation period and the tempera gization of the toast heating elements during ture controlled switch will be actuated to subject operation of and independently of the timer and the slice of bread to a predetermined amount of 65 a bimetal bar, of substantially U-shape, located heat during the toasting operation. If now the same toaster is connected to a supply circuit of out of close heat-receiving relation with the toast heating elements and electrically connected in much higher voltag» say 120 volts, and the same series circuit with the toast heating elements and degree of toasting is desired, the adjustment of the timer will not be changed. The operation of the 70 adapted to actuate said second switch to cause continuous application of toasting heat to a slice temperature controlled switch will be .such that of bread at the start of a toasting operation until the successive energization periods of the toast the bimetal bar has reached a predetermined heatinc1r elements will be shorter when they value and intermittent application of toasting were connected to the 105 volt circuit and the total heat thereafter for recurrent periods determined amount of watt-seconds supplied to the toast 75 by and variable with the value of the input volt 2,412,727 7 age, and to cause the total amount of such heat reaching a slice of bread to be constant irrespec tive of different energizing voltages applied to the toast heating elements. 2. In an automatic electric toaster adapted t0 8 prising toast heating elements, means to start a toasting operation, a main switch for said heat ing elements, a constant speed timer started run ning in response to said starting means to time the toasting period and operative to cause open ing of said main switch at the end of a toasting operation after a ñxed length of time, the im provement comprising means controlling ener operate on electric circuits or" different voltages and at different toaster temperatures and com~ prising toast heating elements, means to start a gization of the heating elements during operation toasting operation, a main switch for said heating elements, a constant speed timer started running 10 of and independently of the timer for ensuring that substantially the same amount of heat from in response to said starting means to time the said toast heating elements shall reach a slice toasting period and operative to cause opening of bread during said fixed length of time of a of said main switch and terminate a toasting op toasting operation irrespective of variations in eration after a preset nxed length of time and t a second control `switch for said toast heating ele 15 the temperature of the toaster and in the ener gizing voltage applied to the toast heating ele ments during operation of and independently of ments, said means including a bimetal bar, of vthe timer, a thermal element out of close thermal substantially U-shape traversed by the same cur relation with said toast heating elements, heated rent carried by the toast heating elements posi in accordance with the current carried by the toast heating elements and adapted to actuate 20 tioned out oí close heat receiving relation with the toast heating elements and a vsecond control said second control switch-to energizewand de switch for said toast heating elements actuable by energize said toast heating elements consecu said bimetal bar for causing consecutive ener tively to cause substantially the same amount of gizaticn and deenergization of the toast heating heat from the toast heating elements to reach a slice or” bread being toasted during said preset 25 elements during a toasting operation and to in crease the total time of energization of the toast ñxed length of time irrespective of the energizing heating elements during said ñxed length of time voltage applied to the toast heating elements. of a toasting operation with decrease in the volt 3. In an automatic electric toaster adapted to age applied to the toast heating elements. operate at different toaster temperatures and on 5. In an automatic electric toaster adapted to electric circuits of different voltages and compris 30 operate on electric circuits of different voltages ing toast heating elements. means to start a toast and comprising toast heating elements, a main ing operation, a main switch for lsaid heating ele switch for said heating elements, means to start ments, a constant speed timer started running a toasting operation, a constant speed timer in response to said starting means to time the toasting period and operative to cause opening of 35 started running in response to said starting means ì to time the toasting period and operative to cause said main switch and terminate a toasting oper opening of said main switch at the end of a toast ation after a preset ñxed length of time, the im ing operation after a ñxed length of time and a provement comprising means for ensuring that second control switch for controlling the ener 'substantially the same amount of heat from said toast heating elements shall reach a slice of bread 40 gization of the toast heating elements during operation of and independently of the timer7 a during said preset fixed length of time of a toast bimetal bar, of substantially U-shape, out ci close ing operation irrespective of variations in the thermal relation with said toast heating elements temperature of the toaster and in the energizing adapted to carry the current ño‘wing through the voltage applied to the toast heating elements, said means including a thermaliy-actuable switch te. Le1 toast heating elements and to actuate said second switch to cause intermittent energization of the controlling energization of said heating elements toast heating elements and intermittent applica during operation of and independently of the tion of relatively high temperature radiant heat timer and positioned out of close heat receiving to a slice of bread being toasted, said thermally relation with the toast heating elements and - heated in accordance with the currentl carried by u aotuable control switch being eiîective to limit the temperature reached by the surface of a slice the toast heating elements for controlling the en of bread being toasted and to cause substantially ergization of the toast heating elements to reduce the same amount of radiant heat to reach a slice the total time of energization of the toast heat of bread being toasted during said fixed length of ing elements during said preset ñXed length of time of a toasting operation with increase in the l. time of a toasting operation irrespective of varia tions in the energizing voltage applied to the toast voltage applied to the toast heating elements. 4. In an automatic electric toaster adapted to operate at different toaster temperatures and on electric circuits Vof different voltages and com heating elements. JOHN R. GOMERSALL. MURRAY IRELAND.