US2392076A - Electric heater - Google Patents

Description

E. WIEGAND 2,392,076

ELECTRIC HEATER Jan. 1, 1946.

2 Sheets-Sheet 1 Original Filed Aug. 25, 1941 I=I W 4 lil lldlifl INVENTOR BY MW 4 ATTORNEYS Jan. 1, 1946. wlEGAND 2,392,076

ELEGTRI C HEATER Original Filed Aug. 25, 1941 2 Sheets-Sheet 2 4550 10 53 J2 55 ,0 l I. r I I Hy I if, wu m m m H 56 J7 7: I

- [0 WW 1. lV/EGfi/VD INVEZl/TOR ET MW 4m,

ATToRNewe Patented Jan. T, 1946 ELECTRIC HEATER Edwin L. Wiegand, Pittsburgh, Pa., assignor to Edwin L. Wiegand Company, Pittsburgh, Pa., a corporation of Pennsylvania Original application August 23, 1941, Serial No.

Divided and this application Decemher 9, 1942, Serial No. 468,383

2 Claims. ((1219-37) My invention relates to electric heaters, more particularly to electric range units, and the principal object of my invention is to provide new and improved electric heaters of these types.

This application is a division of my copending application Serial Number 408,073, filed August 23, 1941.

In the drawings accompanying this specification, and forming a part of this application, I have shown, for purposes of illustration, one form which my invention may assume, and in these drawings: v

Figure 1 is a plan view of an electric rangeunit illustrating an embodiment of the invention,

Figure 2 is a bottom plan view of the embodiment, drawn to a smaller scale,

Figure 3 is a side elevation of the embodiment,

Figure 4 is a bottom plan view, the reflector beiug omitted to better illustrate certain of the par s,

' Figure 5 is a sectional view corresponding generally to the line 5-5 of Figure 4,

Figure 6 is a fragmentary sectional view corresponding generally to theline 6-6 of Figure 5,

Figure 7 is an enlarged sectional view corresponding generally to the line l-l of Figure 5.

The electric heater or range unit embodying,

my invention may comprise one or more heating elements, in this instance two elements 10 and II. As herein shown, each element comprises a tubular metal sheath within which is disposed electrical resistance heating means l2, embedded in refractory electrical-insulating heat-conducting material ii. The insulating material l3 may be in the form of suitable granular, comminuted,

- or powdered refractory material, preferably compacted to a dense hard condition.

Each of the elements l0 and II has an activeportion which is preferably triangular in crosssection, as best shown in Figure 5, and the active portion of-each element is of generally spiral form. Referring particularly to Figures-1 and 4,

' it will be noted that the element I I has a central portion wound about itself for one turn, and the source of, say 220 volts, in such manner that either one or both may be energized, the elements herein shown are designed to provide 2000 watts when both are simultaneously energized. The

' element H is so designed that when it only is energized, it will provide 1400 watts, and this wattage will be spread out over a considerable area, but with some concentration at the center. The element I0 is so designedihat when it only is energized, it will provide 600 watts. Of course, the wattages will be in relation to the voltage used, and in the embodiment it is possible to have other heats. For instance,"if 110 volts were used, the elements l0 and herein disclosed are so designed that when both are. energized they will provide500 watts; when the element ll only is energized, it will provide 350 watts; and when the element 10 only is energized, it will provide 150 watts. Also, it will be apparent that it is possible to employ a switch connected to different voltages, as for example 220 volts and 110 volts,'and so designed that the element may be singly or together energized with either voltage.

'I'he element III has end portions p1, 1122, and the element II has end portions in. 1 4. Each of the end portions terminates in a connection terminal, respectively numbered l4, i5, i6, and H, which may be housed in'a suitable insulating block or housing 18. The terminals l5 and ii ar here shown bridged by a bridge plate l9, and the connection terminals may b connected to a source of electricity (not shown) through the means of a proper electrical switch (also not shown).

The-end portions 111, in, pa, in are all of substantially circular or rounded section, to facilitate bending, and preferably only th spiral portions of the elements are of triangular section. The elements such as may be embodied in the range unit herein shown may initially comprise a tubular sheath of substantially circular cross-section into which the resistor and insulatin maportion of each heating element 10; or H comprises a tubular sheath having two walls 20,, 2|, the major portions of which are flat and make betweenithem anangle of approximately these walls merging in a rounded apex 22. The

upper wall 23 is substantially entirely fiat and makes with the walls 20, 2| angles of 60 respectively. In the embodiment shown, the flat pordially disposed arms 27 to 32 inclusive.

tions of the walls 20, 2| are respectively of less cross-sectional extent than the substantially en-= tirely flat upper wall 23. i

As best seen in Figure 5, the upper walls 23 lie in a common plane. Therefore, if an object, such as a cooking vessel, is placed upon the heating means comprising the heating elements I0, I I, the vessel will be in contact with the fiat upper walls 23, and therefore is in excellent heat-conducting relation with respect to a relatively large area of the heating means, so as to be heated mainly by conduction. The generally downwardly facing lower walls 26, 2| of each heating element radiate some heat diagonally downwardly in respectively opposite directions, considering any given portion of an element, and this heat is reflected upwardly .by a reflector 2% which generally underlies the heating elements Ni, it. The end portions 101, in, pa, in extend downwardly from their respective active portions, and

then have their respective extremities bent slightly upwardly toward the insulating block it, thus forming a drip point 25, best shownin Figure 5 with reference to the portion pa. Preferably all the end portions are brought together at an edge of the range unit, as herein shown, so that external electrical connection thereto is facilitated.

Tracing the various portions of the elements, and starting with the portion pa of the element 5 i, it will be seen that the portion pa extends toward thecenter of the rang unit, upwardly to the active portion, and the active portion is wound about itself at the center at least once, as shown at pa, and then has an intermediate portion pa spiralling to the end portion 124. The element i it starts with the end portion :21 extending upwardly to its active portion, and this active portion is intercalated with respect to the active portion of the element i l except at the central portion 115, and terminates inthe end portion p2.

The apexes 22 of the heating elements It and ii define the under side of the active portion of the heating means, and this under side is mounted upon a supporting means 26, which may be a grating or grid comprising a plurality of generally ra- In the embodiment shown, the supporting means 26 comprisesa straight sheet-metal member, providing the arms 27, 28. The arms 29, 30 are formed by a sheet-metal member bent so as to form a central generally U-shaped bight 33, and-the arms 29, 3B extend from this bight in generally V- shaped relation with respect to each other. Likeaseaove 26. Desirably, the slots are elongated in a radial direction, and in this direction are longer than the width of the clips 38 to allow for relative movement of the elements in a plane defined by the upper margins of the arm 2'! through 32, so

as to accommodate for expansion and contraction 6f the heating elements. In this manner, binding,

straining, or warping of the parts is prevented.

The extremity of the arm 28 is formed with a projection 60 fitting into an aperture M in abracket 52. The bracket 62 is longitudinally curved, as best seen in Figure 4, and at its lowerextremities is provided with fingers 53 extending inwardly of the range unit, and terminating in upwardly directed ledges 433. An upper side mar gin of the bracket ,42 has an angular extension 55 upon which the apex of the element iii, adjacent the end portion p2, rests, thus supporting this part of the element 58, since it is spaced a substantial distance from the arm 32. The lower ,margin of the bracket 62 is formed with a curved which may be grounded to a suitable ground, such as a stove frame or the like.

Circumscribing the outer ends of the arms of the supporting means 26 is a ring at, having a U-shaped bight 3d, and the arms 3!, 32 extend" y from this bight in generally V-shaped relation with respect to each other. The bights 33, 36 are fastened to opposite sides of the sheet-metal member forming the arm 21, 28, as by 'means of rivets 35. If desired, all, or certain of the arms may be provided with stiffening ribs, as indicated by the numeral 35.

Means may be provided to hold means comprising the elements In, H in desired assembly with the supporting means 26. In the embodiment shown, this means comprises a plurality of slots 37 formed in the arm 27, each slot generally underlying the section of the respective heating elements traversed by the arm 2'1, as best seen in Figure 5. A plurality of clips 38 are secured to the apex of each element l0, l1 adjacent the arm 21, as by spot welding, each clip having a tongue 39 extending downwardly generally along a surface of the arm 27, extending thro gh a ethe heating i cylindrical portion 39 merging with an annular portion 56 in turn merging with a downwardly extending cylindrical flange 5 5', adapted to engage a range top (not shown). The arms 27, 3D, and 32 are longer than the other arms, and the longer arms are provided with projections 52 forming shoulders with the respective arm, the projections being adapted to engage respectively in apertures 53 formed in the cylindrical portion 49, and the shoulders being adapted to bear against the adjacent inner peripheral surface ofthe cylindrical portion, so that the ring 18 is adapted to support r the supporting means 26. v The arm 27, adjacent its extremity, is provided with a downwardly extending hook 541. As here shown, the hook is a separate piece and is spot welded to the arm 21. L

The hook 5% has an inclined surface 55 terminating in a hook-tip 5G.

The reflector 2 3 is disposed beneath the supporting means 26, and as best shown in Figure 5, is of generally conical form, or to describe it differently, is generally dish-shaped, with the opening of the dish directed toward the supporting means 25. The peripheral margin of the reflector 2G is formed with a downwardly offset curved portion 51, and the reflector, in line with the hook 56, is formed with a slot 58 of a. length to pass the hook 5d. The reflector 2 has a pocket 59 of generally U-shapedcross-section, as best seen in Figur 6, the bottom wall of the pocket extending radially inwardly, and merging with the reflector wall adjacent a central opening 60 formed in the reflector 24. On either side of the ,pocket 59, the reflector wall is formed with upvvardlyv pressed areas 6|, positioned so that the recess surfaces thus formed are adapted to receive respective ledges as. The hook 5 3 and the ledges 44 provide hanger means from which the reflector is adapted to be hung.

The reflector 24 is adapted for assembly and disassembly with respect to the supporting means by movement generally edgewise of the supporting means. For example, to assemble the reflector 24 with thesupporting means 26, the reflector 24 is moved in a direction generally parallel to the bottom edges of the arms 21 to 32 so that the pocket 59 moves to cover the adjacent parts of the end portions 91, 112, p3, and p4, and the reflector is moved a distance suflicient to align the slot 58 with the hook 54, at which time the reflector is lifted slightly to pass the hook through the slot, and the reflector 24 is again moved slightly in the first direction until'the recess surfaces formed by the upwardly pressed areas SI align with respective ledges 44. At this time, the reflector is permitted to hang, with the recess surfaces of the upwardly pressed areas resting on the ledges 44, and the reflector surface adjacent the slot 58 resting on the hook surface 55. The hook-tip 56 bears against the oflset margin 51 of the reflector, and the hook surface 55 is inclined, so that either or both prevent unintentional reverse disassembly movement of the refiector. To disassemble the reflector 24 from the supporting means 25, a reversal of the assembly movement is necessary.

As best seen in Figure 5, the peripheral margin of the reflector 24 is spaced from the cylindrical wall 49 of the rim 48, to provide a substantially annular air opening 62 (except at the pocket 59) so that air may enter this space radially inwardly and proceed upwardly through the grating and heating element assembly. The downwardly inclined wall of the reflector 24 provides a drainage surface for any substances spilled on the reflector, and these substances may drain through the central opening 60, which opening also provides an additional air opening.

A central medallion 63, or the like, may be provided to cover a desired amount of the space at the center of the heating means. As here shown, the medallion 63 rests on the upper edges of the arms 21 through 32, adjacent the big'ht portions 33, 34, and has marginal extensions, forming four legs 64, which are secured to the side surfaces of the bight portions 33, 34 in any suitable manner, as for instance by spot welding.

From the foregoing it will be apparent to those' skilled in the art that I have accomplished at least the principal-object of my invention, and it also will be apparent to those skilled in the art that the embodiment herein described may be variously changed and modified, without departing from the spirit of the invention, and that the invention is capable of uses and has advantages not herein specifically described; hence it will be appreciated that the herein disclosed embodiment is illustrative only, and that my invention is not limited thereto.

I claim:

1. An electric heating unit comprising supporting means and first and second electric heating elements mounted on said supporting means, having each of said elements intermediate the terminal portions thereof disposed in generally spiral configuration, withthe spirals of the two elements progressing in the same direction, the first element comprising an inner portion extending at least approximately two turns and spiralled on itself, and an outer portion continuing at least approximately one turn, and said second element comprising at least approximately two turns and including an interior portion extending at least approximately one turn and intercalated with said outer portion of said first element.

2. An electric heating unit comprising supporting means and first and second electric heating elements mounted on said supporting means, having each of said elements intermediate the terminal portions thereof disposed in generally spiral configuration, with the spirals of the two elements progressing in the same direction, the first element being of substantially greater heating capacity and comprising an inner portion extendin at least approximately two turns and spiralled on itself, and an outer portion continuing at least approximately one turn, and said second element comprising at least approximately two turns and including an interior portion extending at least approximately one turn and intercalated with said outer portion of said flrst element.

EDWIN L. WIEGAND.

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