US2367500A - Temperature responsive control mechanism - Google Patents

Description

Jan. 16, 1945. A. J. HUCK TEMPERATURE RESPONSIVE CONTROL MECHANISM Filed Nov. 26, 194].

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Patented Jan. 16, 1945 2,367,5l'lll um s'm'rss vPair-Eur "OFFICE TEMPERATURE RESPONSIVE CONTROL MECHANISM Alfred JosephHuck, St. Louis, Mo., asslgnor to Knapp-Monarch Company, St. Louis, Mo., a corporation of Missouri Application November 26, 1941, Serial No. 420,533

Claims. '(01. 161-1) My present invention relates to a temperature responsive control mechanism, and its general object is to provide mechanism of the character shown in Brosseau Patent No. 2,179,811, adapted to overcome certain failings of the Brosseau switchwhen installed on toasters or other electric appliances ci a certain type.

One object of the invention is to provide temperature responsive control means particularly suitable for use with appliances intended to operate in successive cycles, the mechanism being -.heeter, which operates a latch for holding the main switch latched in closed position, also operable to supply heat to a timer element which out in my claims and illustrated in the accompanying drawing, wherein:

Figure 1 is a bottom plan view of a temperature responsive control mechanism embodying my invention, the mechanism being designed for mounting in the base of a toaster in a manner somewhat similar to that shown in the Brosseau patent;

Figure 2 is a side elevation of, the upper part of Figure 1 looking at Figur 1 toward the left;

Figure 3 is a sectional view on the line 3--3 of Figure 1, showing a manual latch operating means;

Figure 4 is a diagrammatic view of the elements of my timer mechanism;

Figure 5 is a sectional view on the line 5--i of Figure 1, showing a timing heater; and

Figure 6 is a sectional view on the line 6-5 of Figure 1, showing the connection of a knob to an adjusting shaft.

On the accompanying drawing I have used the reference numeral ill to indicate a base plate on is heated during the timing period and finally effects energization of the heater whereupon the current ceases flowing through the timer element and it starts to cool down in the Brosseau type of switch, my arrangement being such that heat from the heater is radiated to the timer element to prevent such cooling down and possible recycling and resulting improper operation.

A further object is to provide a latch operating mechanism whereby a latch may be either latched or unlatched manually, and the operating means therefor includes a shaft extending in the plane of the frame of the timer mechanism so that the timer mechanism can he located in the base of a'bread toaster or the like and the shaft extended through the end of the base to terminate in a knob for rocking the shaft.

Still a further object is to provide adjusting means for the timer including a. shaft extending to a position of access outside the toaster base, both the latch actuating shaft and the adjuster shaft having thereon knobs which may be readily adjusted for changing the timing period or matching indicia on the casing of the toaster when the knob is placed in position, a fluted and split shaft being provided, and the knob being a friction fit thereon.

With these and other objects in view,'my invention consists in the construction, arrangement and combination of the various parts of my device whereby the objects contemplated are atwhich the elements of my temperature responsive control mechanism are mounted. A plate of insulation H is secured to the base plate ill, as by rivets l2, and various parts of the mechanism which carry electricity are mounted on the plate ll The timer mechanism includes a main switch comprising switch blades l3 and N. A terminal I5 is provided for the blade l3, and the blade M has a contact element it. to cooperate with the blade I3 in the closed position of the switch, as shown in Figure 2, and by dotted lines in Figure 3.

The switch l3l is adapted to be moved to closed circuit position by a knob l! on a shaft I 8. The shaft l8 is pivoted in perforated ears l9 extending from the base plate [0. A latch releasing cam 20 is secured to the shaft l8. A latch lug 2| is rotatable on the shaft and is limited in rocking movement relative to the cam 20 by an ear 22 on the cam received in an enlarged opening 23. The latch lug 2| has an ex tension 24 to engage an insulation piece 25 on the switch blade H to press the contact 16 into engagement with the blade l3 when the shaft is rotated counterclockwise in Figure 3.

The latch lug 2| is adapted to be latched, as shown by dotted lines in Figure 3, on a latch 26 which is carried by a leaf spring 21. The leaf spring 21 is secured to 2. lug 28 extending from the base plate l0, and an adjusting screw 30 is carried by the latch 26. The adjusting screw has tamed, as hereinafter more fully set forth, pointed 5 an insulated end, indicated at 3 i.

For releasing the latch 26 from the latch lug 2i to thereby permit the switch l3-I4 to open, I provide a latch releasing element 32 formed of bimetal and mounted on a heat bridge bracket 33.

The latch releasing element carries a bimetal extension 34 to engage the insulating button 3! when the latch releasing element warps clockwise in Figure 1 to thus release the latch 26 from the latch ing 2 I.

A heater H is provided for heating the latch releasing element, and causing it to warp in the manner Just described. For controlling the circuit of the heater H I provide a timer element 35 of bimetal, and the timing heater therefor consists of a single loop of resistance ribbon 36, best shown in Figure 5. The timer element 35 is secured to a bracket 31 which is pivoted at 38 so that its upper end may swing, a rivet 39 and a slot permitting such swinging. The bracket 31 is adJusted by an adjusting shaft 4! threaded in a bracket 42 and having thereon an adjusting knob 43. The adjusting knob 43 has a fluted bore, in-

- dicated at 44 in Figure 6, to fit a fluted portion 45 of the shaft 4| so that the adjusting knob can be put on in any one of several circumferential positions. The shaft 4| is split, as indicated at 48, and there is a friction fit between the fluted part of the shaft and the fluted bore of the knob. Thus the knob may be limited to a portion of a revolution, yet the adjustment of the toaster may be'readily changed. If adjustment is desired beyond any range for which it is set between such limits, it is merely necessary to pull the knob off, turn it in the proper direction and replace it so that it assumes a new position of rotation relative to the adjusting shaft 4|.

The timer element 35 carries a contact 41 coperable with another contact 48, which contacts control the heater H, as will hereinafter appear.

The contact 48 is carried by a compensating bimetal element 49 secured to the heat bridge bracket 33, the circuit connections being as illustrated in Figure 4.

The Brosseau patent discloses a switch of the same general character as herein disclosed. However, the arrangement of parts is different, particularly the relation of the heater H to the timer bimetal 35. In my disclosure it will be noted that these two elements are arranged parallel to each other and relatively close to each other. Accordingly, the heater H, when it is energized, radiates heat to the bimetal element 35 for an important purpose, which will hereinafter appear, and which prevents an undesirable recycling operation experienced when the Brosseau switch is applied to certain types of toasters.

Practical operation The main switch l3-l4 is in series with a heating element HE (see Figure 4) of a toaster or the like. The timer is mounted in the hollow base of a toaster, with the plate In suitably secured against the top of the base. The shafts I8 and 4! project to the end and side respectively of the toaster. The knob 43, due to its split, fluted sliding friction fit, permits resetting, if necessary, the color adjustment for the toast beyond the set range of travel of the knob without disassembling the toaster and without the use of any tools. In order to use only one set of molding dies the same knob and the same mounting feature is used also on the latch operating shaft l3. When the latch operating shaft is turned to the on" position by clockwise rotation of the knob l7, the latch lug II is lifted to the position shown by dotted lines in Figure 3, and the latch 26 swings under the -50 to the wire 5|.

latch 1113 to hold it in the dotted Position. This also holds its extension 24 in the dotted position for closing the main switch, thus causing the heating element HE to become energized. The circuit then passes into the heating element and then through the following elements in order (see Figure 4): I5, l3, l6, I4, 33, 43, 43, 41, 35 and II to a terminal 50 with which the line wire 5| is connected. The other line wire I! is connected to the heating element.

If, for any reason, the operator wishes to turn off the toaster manually, the knob II can be rotated counterclockwise so that the cam 23 will force the latch 33 outwardly from under the latch lug 2|, thereby permitting the inherent resiliency of the switch blade l4 to diseng ge the contact II from the switch blade l3.

If the switch is left closed for the timing period, the timing heater 36 heats the timer bimetal 35 so that it deflects in a direction for separating the contact 41 from the contact 43. This happens when the proper toast color as set by the adjusting knob 43 is attained. The circuit now changes so that the current that formerly passed across the contacts 41 and 43 now passes from the heat bridge '33 through the latch actuator bimetal 32 and the heater H to the bracket 31 and then on through the heater 36 and the terminal The heat generated by the heater H warps the actuator 32 toward the right for the element 34 to move the latch 28 in a releasing direction, whereupon the main switch springs open. This ends the first toasting cycle.

The heat bridge 33 carries heat from the actuator 32 across to the bimetal element 49, which element 49 is a compensator for ambient temperature and the bimetal element 34 acts as a latch heat compensator, all as set forth in the Brosseau patent. However, it will be noted that the current during the timing period flows through the timer element 35 so as to act in conjunction with the heater 36 to provide the thermal timing period. When the contacts 41 and 48 separate, then current no longer flows through the timer element 35 so that the timer bimetal 35 is now heated only by the heater 36 and not by the heater plus the current flowing through the element 35 itself. Therefore, there is a tendency for the element 35 to cease deflecting during this period while the heater H is being heated prior to opening the main toaster circuit. During this critical period the timer compensator 49 already begins deflecting very slightly due to the delayed flow of heat received through the bridge 33 from the latch actuator 32. The result is that the timer contacts 41 and 48 close prematurely before the heater H has heated the bimetal element 32 sufiiciently to release the latch 26. This would cause a. recycle condition if it were not for heat radiated from the heater H affecting the bimetal 35 so as to prevent it from deflecting toward the left and thus keeping the contact 41 separated from the contact 43. It is therefore evident that the relation between the heater H and the bimetal element 35 is an important feature of my invention, the arrangement being such that the heater supplies heat to the bimetal element, whereas such was not the case in the Brosseau patent. The spacing between the heater H and. the bimetal 35 may be determined by experiment and then fixed.

I have also provided in my mechanism a compact latch handle assembly permitting a rotary motion of the knob IT, as distinguished from a swinging motion for these parts, as shown in the assasoo 3 Brosseau patent. The switch blade I 4 furnishes the required tension for operating the latch toward unlatched position after manual release or after automatic release instead of a separate spring having to be provided for this purpose.

Some changes may be made in the construction and arrangement of the parts of my device without departing irom the real spirit and purpose or my invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope without sacrificing any of the advantages thereof.

I claim as my invention:

i. In a device of the class described, a normally open main switch, means for manually closing said main switch, a latch for latching said main switch in closed position, means for releasing said latch comprising a temperature responsive timer element, a. heater therefor operable while said main switch is closed, a contact carried by said! timer element, a second contact normally engaged by said first contact, a temperature responsive compensating element for moving said second contact toward said first contact when heated due to ambient temperature rise, said first con-- tact being separable from said second contact upon a predetermined temperature causing said timer element tomove said first contact in a direction of separation relative to said second contact, a temperature responsive actuator for releasing said latch when heated and a second heater for heating said actuator, said second heater being rendered operable by separation of said contacts,'said second heater being closely adjacent said timer element to radiate heat thereto when said second heater' is energized to thereby prevent said timer element from cooling to a position of contactbetween said first and second contacts.

2. In timing means for an electrically operated heating element having an energizing circuit, a relatively flat frame, a main switch carried by said frame for closing said circuit to energize said heating element, a manually operable knob to eflect such closure, a shaft on which said knob is mounted, said shaft having its axis extending parallel to the plane of said relatively fiat frame, latch means carried by said shaft for holding said switch in circuit closing position, said latch means being rendered operable by rotation of said shaft in one direction, a latch releasing. cam carried by said shaft for releasing said latch means from holding position by reverse rotation of said shaft, temperature responsive timing means for actuating said latch means to unlatched position comprising a thermal element and a latch for said latch means, said thermal element being adapted to move said latch out or holding position with respect to said latch means, a heater for said thermal element, a thermal timer to operate said heater, a second heater for said thermal timer in circuit with said main switch, said thermal timer being responsive to heat of said second heater to attain a first heater energizing position until said first heater efiects movement oi said thermal element to position releasing said latch from said latch means. thereby opening said main switch to deenergize said second heater, said second heater during operation supplying heat to said thermal by cause said thermal timer to continue in its second heater energizing position after reaching such position.

3. In timing means for an electrically o ted heating element having an energizing circuit, a main switch for closing said circuit to energize said'heating element, a manually operable knob to efieot such closure, latch means for holding said switch in circuit closing position, temperature responsive timing means for actuating said latch means to unlatchedposition comprising a thermal element and a latch for said latch means, said thermal element being adapted to move said latch out of holding position with respect to said latch means, a first heater for said thermal element, a thermal timer to operate said first heater,

a second heater for said thermal timer in circuit with said main switch, said thermal timer being responsive to heat of saidsecond heater to attain a predetermined position at the end of a timing period, switch means operable by said thermal timer in said predetermined position for energizing said first heater until it effects movement of said thermal element to position releasing said latch from said latch means, thereby opening said main switch to de'enersize said second heater, said first heater during energization thereof supplying sufilcient heat to said thermal timer to prevent the same from cooling, thereby causing said thermal timer to remain in said predetermined position during energization of said first heater.

4. In a device of the class described, a normally Y open main switch, means for manually closing said'rnain switch, a latch for latching said main switch in closed position, means for releasing said latch comprising a current responsive timer including a bimetal element, acontact carried by said bimetal element, a second'contact normally engaged thereby, said first contact being separable from said second contact upon a predetermined current fiow through said timer which causes said bimetal element to move said first contact in a direction of separation relative to said second contact, heater operated means for releasing said latch and rendered operable by said contacts while disengaged, said heater operated means comprising a relatively flat heater arranged in a plane parallel to said bimetal element to supply some of its heat thereto when said heater operated means g is energized, thereby preventing said bimetal eletimer to prevent the same from cooling and therement from cooling to a position of contact between said first and second contacts while said heater operated means is energized.

5. Timing means for an electrical appliance having a heating element comprising a switch for closing a circuit to said heating element, a manually actuated means for operating said switch to circuit closing position, latch means for holding said switch in circuit closing position, a fiat bimetal element for releasing said latchmeanaa heater wrapped around said bimetal element whereby a substantial portion of the heater is exposed throughout the width of a face of said bimetal element, a second fiat blmetal element responsive to current flow during the timing period which affects warping of said second bimetal element to determine the timing period, a second heater for said second bimetal element, said second bimetal element at the end of its timing De-- riod effecting energization 0'! said first heater, said first and second bimetal elements being adjacent each other and in substantially parallel planes whereby said first heater in addition to heatin said first bimetal element radiates heat from said substantial portion thereof to said second bimetal element to prevent cooling thereof as a result of cessation of current flow therethrough at the end 01 the timing period.

ALFRED JOSEPH HUCK.

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