US1649067A - Electrically-heated cup and method of producing same - Google Patents

Description

Nov. 15, 1927. 1,649,067

J. H. KARLSON ELECTRICALLY HEATED CUP AND METHOD OF PRODUCING Filed Jul 15, 1925 2 Sheets-Sheet 1 Nov. 15, 1927. I 1,649,067

J, H. KARLSON ELECTRICALLY HEATED CUP AND METHOD OF PRODUCING SAME Filed July 13, 1925 2 sheets-Sheet 2 Patented Nov. 15, 1927.

UNITED STATES 1,649,067 PATENT OFFICE.-

JULIUS H. KARLSON, OF CHICAGO, ILLINOIS.

ELECTRICAlDLY-HEATED CUP AND METHOD OF PRODUCING SAME.

Application filed July 13, 1925. Serial No. 43,166.

1 element, existing as a helix around the container, will not only have its convolutions thoroughly insulated from the container and from one another, but be insulated from fpossible contact with a body exterior to the winding and from outward dissipation of heat by radiation or convection. Accordingly, one feature of the invention consists in applying to the vessel to be heated, a surface of electrically non-conducting material such, for instance, as sheet mica, winding a helix of electric resistance wire upon said. surface, with the convolutions spaced apart, winding a cord of insulating material, for instance, asbestos fiber, in the spiral path defined by the spaced convolutions of the resistance wire, and then winding a cord of insulating material in the grooves defined by the insulating cord first applied, and therefore in position to overlie the convolutions of the resistance element and complete the housing of the latter, and their heat dispelling insulation on all sides excepting that provided by the wall to be heated.

Another object of the invention is to provide an improved outlet for the ends of the resistance element in a construction of the kind described, and to equip the same with terminals adapted to enter an outlet receptacle and effect electrical connection of the cup with a source of electricity by the act of placing the heating container in position. To this end, another feature of the inven tion consists in enclosing the heating container, after equipping it with the housed re- 5 sistance element, as above described, in an outer shell, uniting the ends of the resistance element to binding posts extending through the bottom of said shell and into an insulation block beneath the bottom, and introducing the circuit closing terminals through the insulation block and into said binding posts; the binding posts being insulated from the bottom of the shell by means of an insulating plate underlying the heads of the binding posts, and non-conducting bushings surrounding the portions of the binding posts which pass through said bottom; the binding posts being secured in such position by means of nuts screwed upon the ends of the binding posts and seated against the insulating block, and the inserted ter- 'minals passing radially through the nuts and into the binding posts, and thereby permanently locking the nuts against unscrewing. Preferably, the outer'shell has its side walls extended a distance beneath its bottom suflici-ent to support its bottom, with the insulating block and contained equipment above the surface upon which the shell stands, and the insulating block has a removable cover which completes the enclosure of the securing nuts and the ends of the binding post upon which they are mounted.

In the accompanying drawings,-

Figure 1 is a vertical axial section of an electrically heated cup prepared in accordance with the method and embodying the several structural features constituting the subject-matter of the present invention.

Figure 2 is a section through a portion of said cup, the plane of section being indicated by the line 2 x of Figure 1.

Figure 3 is a section on the line 8"- x of Figure 1, looking upward.

Figure 4 is a schematic view illustrating the method of applying to the exterior of the inner wall of the cup the electric resistance element and the cord for insulating the same.

Figure 5 is a view illustrative of the method of applying solder to the joint between the inner and outer walls of the cup.

Referring to Figures 1, 2, and 3, 1 represents the inner wall of a cup or container for fluid to be heated, 2 an electrical resistance element coiled about said wall for the purpose of heating the same, and 3 an outer wall concentric with the wall 1',providing means for supporting the latter and developing therewith a space or chamber in which to locate the electric heating equipment. The resistance element 2 is in the form of a wire wound upon the exterior surface of the inner wall 1, after said wall has been faced With sheet mica or other substance efficient as an electrical insulator but relatively low in the insulation of heat, and the convolutions of the resistance element are spaced apart sufficient to have wound between them convolutions 4 of asbestos cord or other substance which is highly resistant to heat in addition to being an electricalnon-conductor; the effect of thus winding the insulating cord between the convolutions of the resistance element being to define a helical channel for the latter. The ends 2 2 of the resistance element thus wound upon the wall 1 are led in any suitable way, for instance, as indicated in the drawing, to a pair of binding posts 5 beneath the bottom of the container 1, and there firmly fixed in a manner to adapt the binding post to serve as means for introducing the resistance element into an electric circuit, as hereinafter described. Having developed the spiral channel for the resistance element 2, said channel is closed on the outer side by a sub stance that is a non-conductor of both heat and electricity, for instance, a second helical winding 6 of asbestos cord, confined in position by the convolutions of the cord first wound on, said closing cord resting upon the cord first wound in a manner to close the grooves against escape of heat from the resistance element either by radiation or convection.

In winding the resistance element and the insulating material upon the receptacle 1, a procedure may be followed such as suggested in Figure 1, wherein 7 represents a revolving head designed to receive the upwardly flaring portion 8 of the receptacle and hold the latter with its cylindrical portion 1 in position to receive the wire 2 from a reel of wire 2*, and an asbestos cord 4 from a reel 4. The outer winding of insulating cord will be applied in the same manner.

Binding posts 5 are mounted in the bottom 9 of the outer shell 3 of the container, being arranged with their heads resting upon a sheet 10 of mica, with their shanks protected from contact with the bottom 9 through means of fiber or other'insulating sleeves 11, while their lower ends 12 are threaded into spanner nuts 13 housed in an insulating block 14- and seated against shoulders 15 in said block. A cover plate 16 of insulating material, secured by screws 17 to the block 14 and also cemented to said block, completes a hermetic housing for all electrically conductive parts in contact with binding posts 5, and renders the electrical connection thoroughly waterproof and the cup immune from impingement by water used in washing it.

In order to complete a circuit with the binding posts 5, terminals 18, fitted watertight through a wall of the block 14, extend radially through the nuts 13 and into the lower ends of the binding posts in a manner to hold the terminals rigidly in a presentation which adapts them for convenient introduction into the sockets of an outlet receptacle, and at the same time to prevent the nut 13 from unscrewing.

The outer shell 3 terminates in a bottom flange 19 which supports the cup with its bottom 9 sufficiently above the surface on which the cup rests to accommodate the block 14; and this supporting flange 19 preferably terminates in an inwardly presented lip 20 which not only affords a better foot for the cup but better adapts the cup to enter into coaction with a sustaining projection when the cup is mounted in position by the long known method of mounting a cup by moving it upward to bring its upper marginal portion into engagement with a member that sustains it laterally, and then swinging the cup inward until its bottom engages over a projection which affords vertical support.

In unitingthe shell 3 with the inner container 1, the latter is preferably provided with a shoulder 21 adjacent the offset between the cylindrical portion 1 and flaring portion 8 of the cup, and against which shoulder the shell 3 is made to abut; and a body of solder or other readily fusible metal 22 is placed in the angle between the inner and outer shells, as shown in Figure 5, so that when the cup is placed upon the rotary table 23 and rotated while played upon by torch 24, the solder is melted and caused to flow by gravity in between the two surfaces that are to be joined, which will include the concentric, conforming and approximately contacting faces of the inner cup flare and the inner face of the outer shell, as well as the two edge faces which abut at the shoulder 21.

I claim:

1. In the art of developing resistance elements upon electrically heated containers, the steps which consist in winding the re sistance element in spaced convolutions upon the wall of the container, winding a cord of insulating material in the spaces between said resistance element to provide a helical channel for the resistance element, and winding a cord of material that is non-conductive of both heat and electricity in the said channel to complete the enclosure of the resistance element and prevent radiation or convection of heat outwardly therefrom.

2. In the art ofdeveloping electric heating means upon a container, the steps which consist in providing upon the outer surface of the container a facing of material that is conductive of heat but non-conductive of electricity, winding upon the surface thus prepared a helix of electric resistance wire with convolutions spaced apart, winding in the spaces between the convolutions a cord of non-combustible material that is resistant to both heat and 'electricity, thereby developing walls of a helical channel in which the resistance element lies, and then winding over said channel a cord of material resistant to heat and electricity and of a size that causes it to impinge against the sides of said channel formed by the cord first wound.

3. In an electrically heated vessel, 8. container, a facing of material that is conductive of heat but non-conductive of electricity, on the outer surface of said container, a helix of electric resistance wire with convolutions spaced apart on said facing, means forming insulation encasing said wire, comprising a 4. In an electrically heated vessel, a container, a facing of material that is conductive of heat but non-conductive of electricity, on the outer surface of said container, alternate convolutions of electric resistance Wire, and non-combustible cord material th t is resistant to both heat and electricity, n said facing, other convolutions of non-combustible cord material positioned over the channels formed by said first named convolutions of non-combustible cord material, forming therewith a casing for said wire convolutions.

5. In an electrically heated vessel, a container having a facing of material that is conductive of heat but non-conductive of electricity, on one surface thereof, convolutions of electric resistance wire. spaced on said facing, a casing over each convolution of wire comprising three cords of non-combustible material that is resistant to both heat and electricity.

6. In an electrically heated vessel, an inner container, an electrical resistance element mounted on said inner container, an outer container, having a wall surrounding said inner container, and a bottom beneath and spaced from the same, and also having a depending skirt portion, providingwith said bottom a cavity, an electrically insulating block in said cavity, binding posts extending from the space between said bottom and inner container, through said bottom and into the insulating block, said binding posts having the ends of said resistance element united to them within said space, and terminals extending laterally through said depending skirt and into the side of said block and transversely into portions of said binding posts located within the block, and means for hermetically sealing said terminals and binding posts.

Signed at Chicago, Illinois, this 8th day of July, 1925.

JULIUS H. KARLSON.

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