US2014001A - Heating element construction - Google Patents

Description

Sept. 10, 1935. A. s. KNAPP ET AL 2,914,001

HEAT I NG ELEMENT CON STRUCTION Filed Aug, 17, 1955 vPatented Sept. 10, 1935 UNITED STATES PATENT OFFICE Stevens, Chattanooga,

Tenn., assignors to Knapp-Monarch Company, Belleville, Ill., a corporation of Missouri Application August 17,

11 Claims.

An object of our present invention is to provide a. heating element construction in which simple, durable and inexpensive means is provided for supporting a resistance element relative to a plate or the like to be heated thereby.

A further object is to provide a heating element construction comprising a plate of sheet metal or the like having outwardly opening slots in the edge thereof and insulating elements received in the slots to project outwardly from the edge of the plate, the insulating elements having notches in their outer ends through which the resistance element extends for supporting it in relation tov the plate and insulating it therefrom.

A further object is to provide a heating element construction in which insulating elements can be associated with plates of various diameters for making small or large diameter heating elements, the insulating elements in each case being the same and the plate only being different for the different sizes of heating elements.

Another object is to provide a heating element consisting of a plate having slots into which insulating elements may be inserted, the elements themselves being grooved so as to retain them against undesired movement in the slots and having notches of peculiar formation in their outer ends whereby the resistance element may be inserted, but cannot readily be disassociated from the notch after the entire heating element is\ assembled.

A further object is to provide a method of manufacturing a heating element assembly comprising the steps of associating a plurality of insulating elements with a center plate so that they project outwardly beyond the edge thereof and the mounting of a coiled resistance wire in notches formed in the outer ends of the insulating element.

A further object is to provide the insulating elements of greater thickness than the diameter of the coiled resistance wire whereby when they are placed against a plate or the like to be heated by the resistance wire they hold the resistance wire spaced and insulated from the plate or the like.

With these and other objects in view our invention consists in the construction, arrangement and combination of the various parts of our device, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in our claims, and illustrated in the accompanying drawing, in which:-

Figure 1 is a vertical sectional view through a wallie iron showing a pair of my heating element constructions associated therewith.

1933, Serial No. 685,584

Figure 2 is a lay-out view of the heating elements only before they are connected to the wallie grids of the Waffle iron.

Figure 3 is an outer end elevation of one of the insulating elements used in our heating element construction showing the resistance element being entered into the notch in the end thereof.

Figure 4 is a sectional view on the line 4-4 of Figure 3.

Figure 5 is a sectional view on the line 5-5 of Figure 2.

Figure 6 is a perspective view lating elements; and

Figure 7 is a diagrammatic view showing a greater number of insulating elements being used on a larger supporting plate.

On the accompanying drawing, we have used the reference numerals I0 and I2 to indicate the lower and upper grids respectively of a waffle iron A. Suitable casings I4 and I6 are provided for heating elements B, which embody our invention and which are secured to the grids.

Each heating element B comprises a plate I8, insulating elements 20 and a resistance element 22. The plate I 8 is provided with radially eX- tending, outwardly opening slots 24 circumferentially spaced around the periphery there-of. The edges of the plate adjacent the sides of the slots are corrugated, as indicated at 26 (see Figures 2 and 5).

Each insulating element 20 is provided on opposite sides with a groove 28.

The insulating elements are adapted to be inserted in the slots 24 of the plate I8 with the edges of the slots and the corrugations 26 received in the grooves 28 which are Wide enough to accommodate both the thickness of the plate and the height of the corrugation. The corrugations serve to provide points of engagement rather' than surfaces of engagement, whereby a better frictional contact between the insulating elements and the plate I8 is had.

The grooves 28 are closer to one edge of the insulating element 20 than the other so that when the plate I8 is assembled therewith, the plate will be quite close to the grid I0 or other surface to be heated by the heating element and can be secured thereto, as by a bolt 30 and a nut 32. The insulating elements 20, it will be noted, are of greater thickness than the diameter Of the resistance element 22 and accordingly when the edges of the insulating elements are placed in contact with the grids IG and I2 or other surface to be heated, regardless of which edge is so placed, they will be holding the resistance Wire of one of the insugeneral directions. On larger spaced from the grid and thus prevent electrical contact between the wire and the grid. A depression 34 in the plate may be provided with contacts the grid to prevent undue strain on the plate I8 when the nut 32 is tightened.

The resistance element 22 is strung through notches 36 which are provided in the outer. ends of the insulating elements 20. Each notch has an entry portion 36a at its outer end which is of slightly greater Width than the diameter of the resistance element, as shown in Figure 3, and the axis of which is at a slight angle relative to the axis of the bottom of the notch 36 Where the resistance element Iinally rests after assembly.k

By this arrangement the resistance element dur ing assembly must be entered into the notch 36 while at an angle relative to the plane of the plate I 8 and when it assumes its finally assembled position, Which is parallel to the plane of the plate, it is retained in the notch by the entry portion 36a.

Three of the insulating elements, as indicated at 20a, may be provided with rivets 38 for the ends of the resistance element wires 40. Another of the insulating elements, as indicated at 20h, may be provided with a rivet 4| for one end of the resistance element and for one end of a terminal prong 42. Another insulating element, as indicated at 2Bc, may be provided with a rivet 44 for a terminal prong 46 and one end of alead wire 4U, all as shown in Figure 2.

InFigure 2, we have shown a plate provided with the insulating elements projecting radially in six plates, additional slots 24 can be provided and additional insulating elements used, such as shown in Figure 7, in which the insulating elements project in eight general directions. Smaller or larger plates with fewer or greater number of slots and insulating elements, it will be obvious, can be thus used for assembling different sizes of heating elements, yet using the same insulating element regardless of size of the finished heating element.

The terminal prongs 42 and 46 are preferably extended through insulating bushings 48 in the casing I4 which help to support the prongs and insulate them from the Waile iron A. The corrugations 26 need not necessarily be provided, although they are found desirable. Means other than the grooves 28 can be provided to prevent undesired movement of the insulating elements relative to the slots 24 and other changes also may be made without departing from the real spirit and purpose of our invention and it is our intention to cover by our claims, any modified forms of structure or use of mechanical equivalents, which may be reasonably included Within their scope;

We claim as our invention:

1. A heating element construction comprising a. circular supporting plate having outwardly opening slots in the periphery thereof, insulating elements received in said slots and having their outer ends spaced from said periphery and notched, a resistance element extending through the notches of said outer ends and shoulders on said insulating elements engaging a surface of said plate to prevent movement of said insulating ellertnent through said slot at right angles to said p a e.

2. A heating element construction comprising a supporting plate having outwardly opening slots in the edge thereof, insulating elements received in said slots and having their outer ends spaced from the edge of said plate, a resistance 22 and for lead element supported adjacent said outer ends, a terminal prong having one end supported by one oi said insulating elements and a casing in enclosing and supporting relation to said heating element construction and in supporting relation 5 to said prong intermediate the ends thereof. Y

3. A heating element construction comprising a supporting plate having peripheral notches, a. plurality of insulating elements each having op posite grooves associated with one oi said notches, 10 projecting outwardly from said plate and having their outer ends spaced from said edge and a resistance element encircling said insulating elements, supported thereby adjacent said outer ends and retaining said insulating elements in position on said edge of said plate.

4. A heating element comprising a. supporting plate having spaced slots in the edge thereof, a plurality of insulating elements received in said slots and having grooves overlapping the edges of said slots, said insulating elements projecting from the edge of said plate and having their outer ends spaced from said edge and a resistance element supported on said insulating elements adjacent their outer ends. 25

5. A heating element comprising a supporting plate having spaced slots in the edge thereof, a plurality of insulating elements received in said slots and having grooves overlapping the edges of said slots, said insulating elements projecting 30 from the edge oi said plate and having their outer ends spaced from said edge and a resistance element encircling said Vinsulating elements, supported thereby adjacent said outer ends and retaining said insulating elements in position on said plate.

6. A heating element construction comprising a circular supporting plate having radially extending slots in the periphery thereof, a plurality of insulating elements received, one in each of 4,0 said slots, projecting from the edge of said plate, having shoulders engaging the surface of said plate adjacent said slots and having their outer ends spaced from said edge and a resistance element supported on said insulating elements adjacent their outer ends.

7. A heating element comprising a supporting plate having slots in the edge thereof, insulating elements having grooves in the sides thereof, said insulating elements being received in said slots with the edges of the plate adjacent the slots therein received in said grooves and a resistance element supported on said insulating elements.

8. A heating element comprising a supporting plate having slots in the edge thereof, insulating elements having grooves in opposite sides thereof, said insulating elements being received in said slots with the edges of the plate adjacent the slots therein received in said grooves, said insulating elements having notches in their outer ends and a resistance element extending through said notches.

9. A heating element comprising a supporting plate having slots in the edge thereof, insulating 05 elements having grooves in the sides thereof received in said slots with the edges of the plate adjacent y the slots therein received in said grooves, lsaid plate having a plurality of corrugations in the edge thereof adjacent said slots, said grooves being Wide enough to embrace both the edges and the corrugations and a resistance element supported on said insulating elements.

l0. A heating element construction comprising a supporting plate having outwardly opening 7' slots in an edge thereof, insulating elements received in said slots and having -their outer ends spaced from said edge and notched, a resistance element extending through the notches of saidv outer ends and a pair of shoulders on at least one side of each of said insulating elements engaging opposite surfaces of said plate to prevent movement of said insulating elements through said slots at right angles to said plate.

11. A heating element comprising a supporting plate having a slot in the edge thereof, an .insulating element having a groove in at least one side thereof, said insulating element being received in said slot with the edge of said supporting plate adjacent the slot therein received in said groove of said insulating element, and a resistance element supported on said insulating element.

FRANK J. STEVENS. ANDREW S. KNAPP.

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