US2320041A - Domestic appliance - Google Patents

Description

y 1943- F. H. M coRMxcK 2,320,041

DOMESTIC APPLIANCE Filed July 5, 1940 4 Sheets-Sheet 1 May 1943. F. H. M CORMICK 2,320,041

DOMESTIC APPLIANCE Filed July 5, 1940 4 Sheets-Sheet 2 May 25, 1943. F. H. MCCORMICK DOMESTIC APFLIANCE Filed July 5* 1940 4 Sheets-Sheet 3 z/z/alNvENTOR. 2

M y 1943- F. H. MCCORMICK 2,320,041

DOMESTIC APPLIANCE Filed July 5, 1940 4 Sheets-Sheet 4 V C/GR M Z C ZE Patented May 25, 1943 I UNITED STATES PATENT OFFICE DOMESTIC APPLIANCE Francis H. McCormick, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application July 5, 1940, Serial'No. 344,018

IGIaim.

This invention relates to a domestic appliance and more particularly to surface heaters for electric ranges.

It is an object of my invention to provide a surface heater of the tubular sheath type in.-

which the upper surface of the sheath is held rig.

. idly in a single plane.

It is another object of my invention to provide an arrangement for a surface heater of the tubular sheath type whereby the heater can be readily cleaned without disturbing the electrical connections.

It is another object of my invention to provide connections. The terminal blocks are so formed an arrangement of a surface heater of the tubuiar sheath type in which the terminal connections are adequately shielded from spillage.

It is another object of my invention to provide a terminal member for a surface heater in which the terminal connections are so located as to be protected from spillage.

It is still another object of my invention to provide a surface heater of the tubular sheath type in which the sheath is very small in diameter so that it may be more readily formed into the desired configuration in order to obtain the desired heat distribution.

It is another object of my invention to provide a two-element surface heater of the tubular sheath type having an improved configuration to provide improved heat distribution.

Further objects and advantages of the present invention will be apparent from the following description, reference being had'to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a top view of one of the surface heaters of an electric range including its terminal block;

Fig. 2 is a sectional view taken along the line 2-2 of Fig. 1;

Fig. 3 is a sectional view taken along the line 3-4 of Fig. 1;

Fig. 4 is a sectional view taken along the line 4l of Fig. 3;

Fig. 5 is a sectional view showing the method of lifting up one of the surface heaters for clean- 8 P p Fig. 6 is an exposed view of the terminal block and connections;

Fig. 'l is a sectional view of the terminal block taken along the line 'l-'I of Fig. 2;

Fig. 8 is a sectional view taken along the line H of Fig. 2;

that the connections from thesurface heating units and from. the switch mechanism enter upon the bottom sides of the block so that the entrances are protected from spillage from above as shown in Fig. 2.

I have shown an electric range in which the surface heaters are of the tubular sheath type. The surface heaters are of the two-element type for general operation with a. three-wire Edison circuit with the inner element operating at maximum wattage when connected to a 115 volt circult and the outer element operating at maximum wattage when connected to a 230 volt circult. The two elements of each unit are welded to a framework and surrounded by a ring in order to insure rigidity. The ends of each of the connections extend downwardly and thence are curved outwardly to terminate in their respective terminal blocks which are located beneath the top surface of the electric range where they are shielded from spillage.

Referring now to the drawings and more particularly to Fig. 1 there is shown a surface heating unit 26 supported in the flanged aperture of the supporting top 22 of an electric range. This heating unit includes an inner element 60 and an outer element 62.

The inner element 60 begins with a looped end 64 and extends in a clockwise direction around a central disk 66 t0 the extent of nearly 360 after which it extends radially outwardly as indicated by the reference character 68, thence downwardly to form a portion indicated by the reference character 10 followed by a lower portion 12 which is curved outwardly and upwardly so that its two end enter the terminal block 14 upon its face 18. This face 16 is turned slightly downwardly so that liquid cannot drain into the interior of the terminal block through the apertures provided for the sheathed elements. The outer element 82 begins with the looped end 18 which i adjacent the radially extending portion 68 and ex-- tends in a counter-clockwise direction around the inner element 60 until it again reaches the radially extending portion 68, after which'it extends of high chrome-nickel steel.

terminal block II through-tho face 25., downwardly and outwardly ex ding portions of both elements are all Each. of the elements contains a helical electrical conductor such as the conductors l4 and 05. These conductors are each surrounded by a suitable electrical insulating material, such as magnesium oxide designated by the reference character 55, and the insulating material is enclosed within a tubular metal sheath. preferably The sheath of the inner element is designated by the reference character 55 and the sheath of the outer element by 52. The elements may be made by any suitable process, for example, one similar to that shown in the Lightioot Patent 1,359,400 may be used for its manufacture. After the elements assaosi The 1 wardly Projecting lip ill which together with a lower projection I ll firmly locks the ends of the channels to the projecting portions of the rim Ill. The lower proiections III 'are bent outwardly as shown in dotted lines in Fig.9 in order to allow the projection I" to be placed in the notch III. After this the proiections I are bent straight again so' that the projections III are firmly locked in place within notches III.

'Ihe rim III is madefrom a straight strip of metal and i curled into circular form with its Joint adjacent the terminal 14. This joint is made rigid by the connecting piece II I which is welded to the two ends of the strip forming the rim so as to make a flrm Joint which is practically invisible. This connecting piece III also serves are bent to the shape shown in Fig. 1 they are slightly flattened upon their upper surface as shown in Figs. 1 and 2, thus providing a greater contact area with the kitchen utensils used.

These elements are rigidly supported upon a framework formedby the crossed stainless steel channel members 04 and 55 which are each provided with a narrow bead 55 for contact welding the members to the bottoms of theelements as hereafter explained. These channels are notched at their centers to provide an overlapping Joint beneath the ornamental disk 55 which is fastened to another disk 55 which in turn is spotwelded to the channel members 54 and 55 in order to reinforce their overlapping joint to flrmly hold the channel members together.

The elements and 52 are preferably fastened to the crossed channels 54 and .55 by contact or to locate the surface heaters radially. since it is provided with a tongue adapted to register with the notch II2 provided in the flange III surrounding the aperture provided in the supporting surface 22 of the range. The rim I55 is provided with a flange .III which rests upon the flange III of the supporting top 22. By this construction the upper suri'acesof each element are maintained rigidly in a single plane.

Beneath each heating unit is a metal reflector- III which may be formed of aluminum coated steel, chrome plated metal or stainless steel in order to reflect the radiant energy from the heating elements for insulating purposes; This reflector I I9 reflects any heat rays from the heatprojection welding. This step is illustrated in, I

Fig. 10 which shows a portion of the inner element III together with a portion of one of the channels 55. As shown, the crossed channel members are supported upon a lower supporting member I52 which is shaped so that it supports 1 the channel members directly beneath'the'narrow bead 55 which is provided for welding Ipurposes. The two elements are'thenplaced upon the crossed channel members in proper .position after which a' pivoted weighted member illflisbrought to bear upon the uppersurface. or-the' elements and 52 in order to hold themfirmly upon the various portions'of thegbeadlfl. [The i lower supporting member I52 is connected bya suitable conductor'I55 to thefsecondar'y'coil ill of a transformer. The primary coil" III of the transformer is connected/tea power source under the control of a; manual switch .152. The

other end of thesecondiau y"coil;I55. is connected by a conductor I to apivote'dsupporting arm I55 for'the weighted members.I". When 1 the;

ing element upwardly onto the bottom surface of the container beingused upon the surface heater. The reflector Ii! is provided with the flange I2I which rests upon the flange II5 beneath the rim I55. The reflector H5 is provided with the drain aperture I25 beneath the central disk 55 so as to catch and drain any spillage which may fall between the convolutions of the heating elements from the containers used on top of the rang'e. The spillage will pass through the flanged aperture I23 onto a drain pan normally provided beneath the reflector. The reflector I I! isprovided with a cut-out or cut-away portion I25 through which the downwardly extendingportions Iii and 55 ofthe inner and outer heating elements pass.

,1: shouldbe noted that the terminal block is is not beneath the heating unit but is beneath the supporting top 22 of the range so that any liquid f-which spills upon the heating unit will not fail upon theterinihal block and possibly'enter to ca'usefa short circuit. Also by curving the terminal outwardly infthe manner described the entire assembled heating element-may be lifted upswitch I52 is closed :currentjpasses' through'the secondary circuit and sufli'cient current to weld wardly asshown in .Fig. 5 without disturbing the electrical connections to the switch mechanism. This exposes the reflector II! which may also be lifted and entirely removed for more convenient :cleaning if desired, without further disturbance.

passes between the elementsand the, channels I at the crossing points between the beads and the various portions of the elements. This DiOV'ides portion of the heating unit. ill-call this, projec tion welding;

The opposite ends a simple method for. simultaneously welding'the elements to the channels at-the-crossing points I as the conductor terminal of'the channel members are I provided withnotches similar to the notch IlI- in Fig.3. Each ofthese notches 'IOI receives the adjacent struck-in portion III of the rim Ill Within the sheathing of each vical electrical resistors are connected at their ends to a solid electrical conductor terminal such I3I.- This conductor Ill protrudesv from the end of the sheathing which is cut of! to expose the end of the solid conductor-terminal Iii. The end of the sheathing is fitted into a metal cap is: which is fastened to the terminal block I4 by the screws I 25 which are threaded into'the bushing I21. The terminal block- 14 is molded of some suitable electrical insulating plastic as shown in Fig. c with the threaded bushing I2Ijlodged directly in the'recess element, the he1-.

I29. The conductor I3I within the terminal block 14 issecurely fastened to a rectangular terminal lug I31.

When the cap I33 is fastened in place upon the terminal block 14, the terminal lugs I31 extend into the recesses I39. The threaded aperture MI in each of the terminal lugs I31 then registers with the center of one of the round passages I43 extending to the face I45 of the terminal block 14. A cup washer I41 fits into each of the recesses I43 and one of the binding screws I49 receives the eyeletted end of one of the flexible conductors I50 extending from the switch mechanism. Each of these binding screws extend through the aperture in one of the cup washers I41 and is threaded into one of the terminal lugs I31 in order to provide the necessary electrical connection between the particular flexible conductor extending from the/switch mechanism and the conductor terminal I3I which connects to the helical conductor within the sheathing. When in operating position, the face 16 as well as the face I45 of the terminal block 14 are each turned partially downwardly so that liquid falling upon the terminal block in its normal position will not enter the passages provided for the difierent conductors but these passages will be protected by the impervious upper faces of the block.

This two-part heating unit is connected to a three-wire Edison circuit through a multi-heat switch mechanism to secure various other lower wattage inputs with resulting changes in heat distribution for various cooking purposes. Several of the circuits which apply are disclosed in my copending application S. N. 236,471, filed ctober 22, 1938.

In Fig. 9 I have shown a heating unit which is larger in size than the unit shown in Figs. 1 to 5, but which is identical in other respects excepting that the outer element 222 is provided with a loop 226 within the inner elements 224. Like the smaller unit 26 the larger unit is supported within the flanged aperture of the range top 226 which covers the terminal block 228. The unit is provided with a rim 230 which rests upon the flange of the aperture in the range top 226. This rim is provided with struck-in portions 232 which support the ends of the crossed stainless steel channel members 234 which are each provided with a narrow welding bead 236 upon which rests the bottoms of the two elements at the points at which they cross the channel members 234. The channel members 234 are provided with a orntral disk 238 as in the smaller unit. The elements 222 and 224 are fastened to the crossed channel members by projection welding as in the smaller unit. The end portions of the elements extend downwardly and are curved outwardly so that they extend into one of the downwardly turned faces of the terminal block 228 exactly in the manner as shown best in Figs. 2 and 5 in connection with the smaller unit.

The provision of the additional inner loop 226 '6: the outer element 222 greatly improves the heat distribution of the larger unit by providing heat in the center as well as the edge portions by the outer element and in particular makes it possible to make the outer element much longer than the inner element. This lends itself admirably to my preferred arrangement of operating the inner element at a maximum wattage upon volts and the outer element at maximum wattage upon 230 volts in standard three-wire Edison circuit.

As mentioned in connection with the smaller unit, the elements of the larger unit are connected by flexible electric conductors to a multiheat switch mechanism which in turn is connected to a three-wire Edison circuit source in order to secure various lower wattage inputs with resulting changes. Several of the circuits which apply are disclosed in my co-pending application S. N. 236,471, filed October 22, 1938.

While the form of embodiment ofthe invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claim which follows.

What is claimed is as follows:

A multi-element surface heater of the tubular sheath type including a tubular double loop sheath element extending in a substantially circular fashion for nearly 360, a second tubular sheath element having a, single substantially circular loop portion within and in the same plane as the first element, said second element having a double loop second portion extending in a sub-' stantially circular fashion outside of and in the same plane as the first element.

FRANCIS H. MCCORMICK.

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