US1686108A

US1686108A - Electrical heating apparatus

Info

Publication number: US1686108A
Application number: US72880A
Authority: US
Inventors: Harold N Shaw
Original assignee: GLOBAR CORP
Current assignee: GLOBAR Corp
Priority date: 1925-12-03
Filing date: 1925-12-03
Publication date: 1928-10-02
Anticipated expiration: 1945-10-02

Description

Oct.2,1928. I 1,686,108

H. N. SHAW ELEOTRICAL' HEATING APPARATUS Filed Dec. 1925 2. Sheets-Sheet 1 Oct. 2, 1928. 1,686,108

H. N SHAW ELECTRIGKL HEATING APPARATUS Filed Dec. 5. 1925 2 Shets-Sheet 2 Patented Oct. 2, 1928.

UNITED STATES PATENT OFFICE.

HAROLD N. SHAW OF MILWAUKEE, WISCONSIN, ASSIGNOR, BY MESNE ASSIGNMENTS, TO GLOBAR CORPORATION, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF NEW YORK.

Application filed December This invention relates in general to elec trical heating apparatus and has more particular relation to heating units of a type adapted for domestic and the like heating purposes, as for instance, hot plates for individual use and for insertion or incorpora tion as a partof electric cooking stoves or ranges and the like.

A general purpose of the present invention is the production of an electrical heating appliance, wherein the heating element or elements are of such a character and so mounted or disposed as to satisfactorily permit a relatively high degree of heat to be produced or generated and a maximum of such generated heat to be transmitted directly to or reflected upon the body or article tobe heated, rather than to be absorbed in heating refractory or the like supports and mountings or accessories which have little useful effect in the matter of permitting or promoting efficient heat transmission or utilization. Other advantages may be secured in accordance with the present invention through the use of heating elements which are self-sustaining at temperatures beyond those normally commerically attainable with metallic resistors, thus permitting concentration of maximum heating effects, and through the mechanically and electri- 1 cally eflicient supporting or mounting of these heating elements in such a manner as to leave substantially the entire surface of the heat generating portion of the individual heating elements exposed and free to readily transmit heat to the point desired, and, likewise, in such a manner as to permit varia' tion in the connections of individual heating elements, so as to vary the total heating effects, and also to permit ready removal and replacement of individual heating ele ments through a relatively simple operation.

It is an object of the present invention to provide an electrical heating apparatus of the above general character which is of improved design and construction and which is highly efficientin operation and relatively inexpensive in the matter of original and maintenance costs;

It is a further object of the present invention to provide an electrical heating apparatus of this general character which is of improved design and construction embodying heating units of the self-sustaining type which are readily detachable from and re- 3, 1925. Serial No. 7 2,880.

placeable in operative position, and wherein the heating units are held in mechanically and electrically operative position through yielding frictional engagement of supporting contact elements.

It is a. further object of the present invention to provide an electrical heating apparatus of improved design and construction embodying a plurality of heating units of the self-sustaining type which are so mounted as to be readily detachable from and replaceable in operative position, and .so as to dispose substantially the entire effective heating portions of the heating units in such an unobstructed manner as to permit maximum radiation efliciency and use ful heat transfer.

It is a further object of the present invention to provide an electrical heating apparatus of the above described character and embodying as a feature or features an efficient heat insulator and reflector element associated therewith for insuring maximum efficiency in the matter of concentration of the heat at the point desired, and novel means for definitely determining the operative position and mechanically and electrically mounting the support for the heating units of the apparatus in operative position in a readily detachable manner.

These and other objects and advantages are attained by the present invention, various novel features of which will be apparent from the accompanying description and drawings, disclosing several embodiments of the invention, and will be more particularly pointed out in the claims.

In the accompanying drawings;

Fig. 1 is a sectional elevation of an electrically heated hot plate embodying features of the present invention, the plane of section being that of the line I--I of Fig. 2.

Fig. 2 is a bottom plan view, with parts in section, of a removable portion of the apparatus shown in Fig. 1.

Fig. 3 is a sectional elevation of another embodiment of the invention, the sectional plane being that of the line IIIIII of Fig. 4e.

Fig. 4 is a bottom plan view, with parts in section, of a portion of the apparatus of the hot plate shown in Fig. 3.

Figs. 5 and 6 are views in elevation of a detail of the apparatus shown in Figs. 3 and 4.

In accordance with the disclosure of Fig.

1, the invention is applied to an electrical ,mounted on a suitable support, or for use as one of the several heating elementsof a cooking or the like range. As indicated, the hot-plate comprises a frame 10 of circular outline and having an upper plate-like portion 11 of desired smoothness or surface finish at its upper side, to suitably support a cooking utensil, or other article to be heated, and including a central hub portion 12 with an extension at its lower side, peripheral portions of the plate 11 being united to the central portion 12 by a pluralit of diametrical ribs 14 arranged at substantially right angles to each other, thus providing four triangular apertures 15 in the plate. While a specific form of apertured plate is shown and described, it will be apparent that the form and shape of this plate may be considerably altered without in any way affecting major considerations of the present invention.

The plate 11 is provided with a plurality of projections or rib-like flanges 16 at its underside, which may be arranged to form an enclosure of rectangular or the like outline, as indicated, these ribs being located fairly close to the outer periphery of the plate. A downwardly extending projection of the hub 12 is preferably of reduced diameter at its lower face, the lower surface of this projection being in substantially the same plane as the lower edge of the flanges 16. Projections or shoulders 18 extend from the inner side of each of the ribs or flanges 16 at substantially right angles thereto and adjacent one end thereof; and each rib or flange 16 is apertured in substantial alinement with an intermediate point on the projection 18 of an adjacent flange 16. A contact piece 20 is mounted on the face of each projection 18 opposite the aperture in the adjacent flange 16, the ex osed face of the contact piece being prefera ly provided with a concave or recessed portion.

There is mounted on the outer side of each of the ribs or flanges 16, a conductive terminal block 23 of brass, aluminum, or the like,

each terminal block carrying a terminal pin.

24 having a reduced lower end; and the terminal block is mechanically secured in operative position and electrically insulated from the corresponding flange 16 by screws or bolts 25 passing through insulating tubes or bushings 26 in the terminal block 23 and threaded into the flange 16. A washer 27 may be formed on the insulating tube 26' beneath the head of the screw 25, and an insulating spacer 28 ma be provided between the block'23 and t e flange 16. The means for securing the block in operative position on the flange 16 may also serve'to secure a relative stiff and resilient contact strip 29 of heat-resistant and resilient conductive material, such as Monel metal, a suitable bronze or the like. A contact strip 31 of heat-resistant conductive material, such as'aluminum or a chromium alloy, such as ascoloy, may be secured to and supported on the inner side of the relatively stiff resilient element 29, as by riveting, welding or the like. The outer end of each of the contact strips 31 and the resilient supporting strips 29 has a concave recess formed therein, as indicated at 32, this recessed contact portion being in substantial alinement with the center of the aperture 19 in the flange 16 on which the resilient contact strip 29 is mounted through terminal block 23. Insulating spacers 34 may be provided on the outer side of the ribs 16, or the adjacent side of the contact strip 31, to "prevent direct contact between these parts at any time.

Resistance heating elements of the rigid or self-sustaining type are indicated at 35, these heating elements or units being preferably of a non-metallic or carbonaceous character and in the form of molded and heat hardened bodies essentially constituted of silicon carbide, with or without resistance modifying materials, and having their ter minal portions of somewhat rounded surface formation and of materially increased electrical conductivity. The heating units 35 have their ends in butt-end engagement with recessed contact end 32 ofthe contact strip 31 and the contact recess in the corresponding contact piece 20, these units being of such leiwth and the position and stiffness of the

resiient contact elements

29, 31 being such that each of the heating units'is resiliently or yieldingly maintained or supported in operative position, through the normal bias of the supporting strip 29, with its terminals in forcible end-abutting engagement with the recessed contact 20 on the projection 18 and the contact 32 formed in the

resilient contact stri

29, 31. As indicated, one end of the heating unit projects through the corresponding aperture 19 in one of the flanges 16, being spaced from the walls of the aperture to a substantial degree and projecting to a slight extent beyondthe outer side of the flange 16.

A tray or drip plate 36 of metal capable of assumin and retaining a relatively high finish or po i sh, aluminum being suitable for the purpose, is provided with perpiheralflanges 37 capable of readily frictionally gripping the lower edges of the flanges 16 m such a manner as to detachably maintain the medium of the.

but securely held or supported in mechanically and electrically operative position through the stiflness and resilience of the contact springs 29.. With the heating elements electrically and mechanically mounted through butt-end engagement with the

contacts

20 and 32,- in the mannerv indicated, it will be apparent that substantially the entire heat producing portion of the re-- sistance element is exposed and free to readily radiate heat. Likewise, with these,

. same being ordinarily in the form of a portion of the top. of a range or like heating appliance. This frame is apertured as indicated, being provided with a recessed shoulder 42 along its inner edge for cooperation with the periphery of the frame 10, so as to support the frame 10 by having the peripheral projection 43 thereon rest upon the shoulder 42. An enclosing housing 45 is provided, the same being of relatively stifl sheet metal formed in the shape of a shallow tray and secured at its upper edges to a portion of the support 41. Mounted upon the bottom of a housing 45 is a block 46 of refractory insulating material, preferably of a generally porous nature and highly heatresistant, this block extending into close proximity to the lower side of the reflector or drip plate 36. With this arrangement, especially when the refractory insulating material 46 does not readily'absorb heat, there is little dissipation or radiation of heat from the reflector 36, except the direct radiation and the reflection from the upper side thereof to the article or utensil supported at the upper side of the plate 11.

As indicated herein, the frame 10 with which the flanges 16 and the projections 18 are united or integral serves as one common terminal for the several heating units 35. The outer end of each of the heating units is electrically connected, through the contact strip 31 and the spring 29, the terminal block 23 and terminal pin 24, to a suitable terminal of a supply line, the frame 10 constituting the other terminal and being usually grounded. As indicated, with the parts in the position shown in Fig. 1, the lower ends of the terminal pins 24 detachably engage within socket contact elements 51 which are secured in insulating bushings 52 and suitably connected to line terminals 53, the insulating bushings 52 with their contact sockets 51 being suitably secured in operative position in the bottom of the housing 45, as by means of retaining collars 54 attached to the bushings, and guiding collars 55, the latter being maintained in operative position as by being secured to a side wall of the housing. I

As indicated, one of the terminal pins, indicated as 24, may be of special size or conformation for cooperation with a correspondingly shaped socket member in the housing 45, this relative arrangement of the contact pins and their sockets insuring that a definite position of the frame 10 upon or within the support 41 can be readily secured by merely adjusting the frame 10 to the position wherein the pin 24 is alined with its particular correspondingly shaped socket 51 and the other pins 24 are in alinement with their corresponding sockets 51, at which time the frame 10 and associated parts may be forced downwardly to the operative position indicated in the drawings, and the desired circuit connections may be established through the several heating units.

As indicated in Figs. 3 and 4, the frame 10 has an upper plate 11 having an annular peripheral portion joined to the central hub portion 12 by means of ribs or spokes 14 disposed in directions approximating radii of a circle but still provided with a substantial reverse bend or curvature, a desirable shape being substantially that of an involute. \Vith this arrangement, any longitudinal expansion of the ribs or spokes due to heating may be taken up in the bent or curved portion thereof without the exertion of such strains as will cause fracture of the spokes.

The plate 11 is provided with a downwardly extending circular flange 16 As indicated, a plurality of terminal blocks 23*, 23*, 23, 23 are secured upon the outside of and insulated'from spaced enlarged portions of the circular flange 16, the terminal blocks having terminal vpins 24 24*, 24, 24 respectively, and the method of securing these contact blocks in position be ing generally similar to that described for securing the contact blocks of Fig. 1, in accordance with which screws 25 pass through insulating bushings 26 in apertures in the terminal block, the bushing being flanged at its outer end 27 beneath the head of the screw, and the inner end of the screw being threaded into the enlarged portion of the flange 16*, with an insulating spacer 28 arranged between the terminal block and the flange 16*. As indicated, relatively stiff and resilient contact springs 57 are mounted at one end on the several contact blocks, being held in desired mechanical and electrical relation therewith by the screws 25, these resilient contact springs being each provided with a contact strip 58, welded, riveted or otherwise secured to its contact spring, a contact recess 59 being formed in the outer end portion of the strip 58 and,

if desired, in the contact springs, the general shape of the contact springs and strips being slightly curved to correspond with the curvature of the flange 16 As indicated, the fixed ends of the contact springs are insulated from flange 16 by the spacer 28, and the contact block 23 is insulated from its contact spring 57 by the insulating spacer 30. These

contact elements

57, 58 extend to a point adjacent the adjacent contact block 23, the contact recesses 59 being each in substantial alinement with a substantially radially extending aperture 19 through the flange 16 Secured in position on and disposed beneath the central portion or hub 12 of the plate 11 are two

complementary contact pieces

61, 62, each being provided with a recess 63 midway its length. thls recess extending approximately half way through the contact piece. The remaining bridge or unrecessed intermediate portion of each con tact piece fits into the recess of the other contact piece, with the two pieces arranged in the form of a cross with the arms extending at right angles to each other, and sheets of mica 63, or other sheet insulating material, are disposed between the adjacent side walls or surfaces of the two contact pieces, and a sheet 64 of similar material between the overlapped or superposed bridge portions formed by the recesses 63, to effectively insulate one contact piece from the other throughout. Each of the superposed portions of the contact pieces is provided with a through central aperture, 66, the apertures in the two pieces being in alinement when the pieces are in the position indicated. These

contact pieces

61 and 62 are held in desired position by means of asecuring screw or bolt 67 passing through the apertures 66 and an insulating bushing therein, being thus insulated from the contact pieces, and having its end threaded into the hub 12 a retaining or hearing plate or washer 68 being provided beneath the head of the screw 67 and having extended bearing upon the under side of each of the

contact pieces

61, 62 to assist in effectively maintaining these contact pieces in the positions indicated; Insulating spacers are disposed between the bearing plate 68 and the contact pieces 61. 62 and between the latter and the hub portion 12 of the plate. as indicated, to complete the insulation of these contact pieces one from the other and from the frame. Spacing or positioning studs 69 having their body portions .of substantially rectangular cross-section, are disposed between the bearing plate 68 and the hub portion 12", these studs 69 preferably having their ends of generally circular cross-section and fitting in correspondingly shaped recesses in both the hub and the bearing plate 68. These studs or pins are preferably of metal and suitably insulated from the sides of the

contact pieces

61 and 62 by the insulating sheets or strips 64, the cooperative engagement of the sides of these studs with the insulating strips serving to definitely position the contact pieces.

The

contact pieces

61, 62 are provided adjacent each end and on opposite sides of the center lines thereof with contact recesses 61; 61", and 62*, 62 respectively. These contact recesses are of approximately the in a

resilient contact element

57, 58, and one of the contact recesses 61, 61 and 62* and 62 in the

bridging contact pieces

61, 62, the body portion of the resistance element being substantinally entirely disposed within the flange or rib 16, the outer end thereof extending through the aperture 19 in .the flange, being free of the walls of the aperture, and the outer terminal end of the heating unit being disposed within the contact recess 59. As described heretofore, the mounting strips 57 are of such strength and resilience and so supported as to cause the heating unit 85 to be forcibly but nevertheless yieldingly maintained in operative position with mechanically and electrically elfec tive engagement maintained between the conductive terminal ends of the heating unit and the walls of the contact recesses 59 and the contact recesses 61, 61 62 and 62 the desired mechanical and electrical mounting being secured and maintained by the force exerted by the resilient contact element 57 in the general direction of the axis of the heating unit. Insulating spacers 34 may be secured to the outer side of the flange 16*- in position to prevent actual contact between any portion of the

contact spring

57, 58 and the flange 16.

As indicated, the

conductive pieces

61, 62 serve as bridging connectors for connecting pairs of heating units 85 in series between pairs of

contact mountings

57, 58 approximately 180 degrees apart and their corresponding terminal blocks. The electrical connections from the several terminal ins may be carried out separately to any desired form of switch or circuit-changing means which will provide for any desired series, parallel or series-parallel connection of the several heating units.

As indicated in Fig. 4, a lead or jumper 83 may permanently connect the contact block 23 being secured thereto by the screws 25, to the contact strip 57 which is supported or held in position by the contact ment being such that active circuit connections need be taken out from only contact terminal pins 24", 24 and 24 the terminal pin 24 being dead in so far as its outside circuit connectionis concerned. With this arrangement, and the frame 10 in operative position in its support, as indicated in Fig. 3, it may be considered that three terminals of a switch or circuit-changing device are connected to the terminal pins 24", 24 and 24. In one condition of the switch, the circuit is to the terminal pin 24 and block 23, whence one ,branch of the circuit passes through jumper 83, contact spring 57 connected thereto, heating element 85, through recessed

contact portions

61 and 61 of,

contact piece 61, heating element 85 associated with contact 61, contact spring 57 and terminal block 23 connected thereto, and thence through contact pin 24 to a second terminal of the controlling switch; and the other branch of the circuit passes from ontact block 23, through contact stri 57 and the heating element 85 associated therewith, through recessed

contact portions

62 and 62 of contact piece 62, heating element '85 and contact strip 57 associated therewith, contact block 23", and through terminal pin 24*, to a third terminal of the switch or to the same terminal to which terminal pin 23 is connected. With this arrangement, the four heating units are connected between the supply line, in two parallel connected groups, each of these groups including two bars in series. This arrangement of the heating units between the terminals of a supply line represents the one ordinarily used for cooking or the like heating purpose.

By suitable switch arrangement to disconnect the terminal pin 24 from the supply line, leaving the terminal pins 24 and 24 connected across the supply line, the four heating units are connected in series, giving a resultant reduced heating effect. This series circuit will be apparent, from terminal pin 24 and its terminal block 23", and associated contact spring 57 and heating element 85, throu h contact piece 62, through the heating e ement and contact spring associated with contact block 23, jumper 83, and contact spring and heating element associated with cont-act block 23?, contact piece 61, and the heating element and contact spning associated with contact block 23, thence to the terminal pin 24 associated with the other side of the supply line. As in the apparatus of Figs. and 2, the terminal pin 24 is of special size or'shape to fit in the a socket member of corresponding size and shape carried by the housing 45. It will be apparent that other desired arrangements as to heating effects may be produced; and in this connection, the

contact pieces

61, 62 may be provided with terminal pins and the housing 45 with suitable corresponding contactsockets extending through the insulating block 46 for cooperation with such ter minal pins, such an arrangement permitting the individual heating elements to be connected in parallel.

Other details of the hot-plate of Figs. 3 and 4 and the means for mechanically and electrically mounting thesanie in operative position will be apparent from the detailed description of features of Figs. ,1 and 2.

With the heating elements arranged as in Figs. 3 and 4, that is, extending substantially radially from a central point of the plate 11 and so disposed as to have practically the entire length of each heating element which is effective for heat-producing purposes opposite a recess of the plate, the utensil or other article on the upper side of the plate is. exposed to the full heat produced by the several heating elements and radiated directly or reflected from the tray 36, a result being that any desired heating effect may be produced in a minimum 0 time, since there is no appreciable loss of heat such as would ordinarily occur in heating refractory or other supports and mountings for the heating elements.

It will be apparent that in either of the forms of the invention disclosed, any heating element may be readily removed from operative position either after the hot-plate has been removed from operative position and the reflector or dri plate 36 removed, or from the upper side of the plate even when the latter is in operative position, it being necessary merely to forcibly withdraw the recessed terminal contact portion on the resilient contact strips 29, 31 of Fig. 2 or 57 58 of Fig. 4, from the outer end of the heating unit or element. Under these circumstances, the inner end of the heating unit may be readily removed from the recessed contact portion 20 carried by the frame in Figs. 1 and 2, or from the contact recesses of the

conductive pieces

61, 62 mounted u on the hub of the plate 11 in Figs. 3 an 4. With the inner end of the heating unit removed from its fixed contact recess, it can be readily tilted so as to pers mit withdrawal of the outer end of the unit inwardl through the

aperture

19 or 19 and thus in 1y removed through the apertures late 11 or 11, or rom the rear or lower side of the frame. It will be apparent that the same or a replacement heating unit may be readily inserted to operative position in a corresponding manner, that 1s, by inserting one end thereof through the aperfixed recessed

contact

20, or 61*, 61 62, 62

Aside from the efiicient heating results secured through the above described hotplate and the facility for: ready removal and replacement of the cartridge-like heating units or elements thereof, the apparatus has the distinct and decided advantage and the metallic contact terminals are maintained in proper condition against deterioration in spite of high operating temperatures of the heating element with its more highly conductive terminal portions and the type of mounting which permits ready radiation or transfer of heat from the active heating portion of the heating element, and the further advantage that all parts of the apparatus are readily accessible and visible and may be readily removed and replaced to effect inspection and cleaning of such parts, to the end that the apparatus is readily and easily maintained in a safe and sanitary condition.. c

It should be understood that the invention claimed is not limited to the, exact details of construction shown and described herein, for various modifications will be apparent to personsskilled in this particular art.

It is claimed and desired to secure by Letters Patent:

1. In an electrical heating appliance, in combination with a supporting frame having apertured wall portions extending downwardly from the upper edge of the frame, a plurality of contacts mounted on the under side of said frame in substantial alinement with alined apertures in said wall portions, and a self-sustaining resistance heating element having a portion movable through an aperture in one of said wall portions and yieldingly and detachably mounted in electrically operative position by said contacts through butt-end engagement between said contacts and said heating element.

2. In an electrical heating appliance, in combination with a supporting frame, a plurality of contacts mounted on the under side of said frame, and a self-sustaining resistance heating element yieldingly and detachably mounted in mechanically and electrically operative position through butt-end engagement of contacts with the terminal portions of said heating element, one of said contacts being of a yielding character.

3-. In an electrical heating appliance, in combination with a supporting frame inv eluding a plate-like element and portions depending therefrom, a lurality of contacts mounted on the depen ing portions of said frame, certain of said contacts bein yielding, and a plurality of resistance heating elements yieldingly and detachably mounted in mechanically and electrically operative position through forcible and yielding buttend engagement of one ofsaid contacts with an end of said heatirig element, certain of said contacts 'being electrically connected together whereby a plurality of said heating elements are connected in the same circuit. 4. In an electrical heating appliance, in combination with a supporting frame having a central hub, and ribs radiating therefrom and providing intermediate openings in said frame, contacts carried by said frame, and self-sustaining resistance heating elements carried by said frame at the under side thereof and electrically associated with said contacts, said heating elements being substantially wholly disposed opposite the openings between said ribs.

5. In an electrical heating appliance, in combination with a supporting frame having a central hub, and ribs radiating therefrom and providing intermediate openings in said frame, contacts carried by said frame, and a resistance heating element carried by said frame and electrically associated with said contacts, said ribs each having a reversely bent portion adapted to take upi expansion strains in said Iibs incident to eating effects produced by said heating element. 6. In an electrical heating appliance, in combination with a supporting frame having a central hub, and ribs radiating therefrom and providing intermediate openings in said frame, contacts carried by said frame, and

self-sustaining resistance heating elements carried by said frame at the under side thereof and electrically associated with-said contacts, said heating elements being substantially wholly disposed opposite the openings between said ribs, and said ribs each having a reversely curved portion adapted to compensate for heating effects produced in said frame by said heating elements 7. In combination in an electrically heated apparatus, a supporting frame, depending projections on the under side ofsaid frame, contacts carried by said projections, certain of said contacts being yieldable, and a plurality of self-sustaining resistance heating elements detachably held in mechanically and electrically operative position in said frame through yielding butt-end engagement of said contacts on the ends of said resistance elements.

8. In combination in an electrically heated apparatus, an apertured supporting frame, depending projections on the under side of said frame, contacts carried by said projections, one of said contacts being yieldable and including a resilient contact strip supported at one end and having a contact recess at another portion thereof, and a selfsustaining resistance heating element detachably held in. yielding frictional engagement between said yieldable contact and a second their body portions within said flange and terminal portions extending through the apertures in said flange into end-abutting engagement with said yielding contacts, said contacts being adapted to yieldably and detachably mount said resistance element in operative position.

10. In an electrical heating appliance, the combination of a supporting frame having a central depending hub-like supporting element provided with a plurality of contacts, spaced peripheral contacts, and spaced radially extending, self-sustaining resistance heating elements detachably mounted between pairs of said central and peripheral contacts. I

11. In an electrical heating appliance, the combination of a supporting frame having a central depending hub-like supporting element provlded with a plurality of contacts, spaced resiliently and yieldingly positioned peripheral contacts, and spaced radially ex tending self-sustaining resistance heating elements each mounted in mechanically and electrically operative position between one of said hub contacts and one of said yielding peripheral contacts through butt-end engagement between said contacts and the ends of said heating elements.

12. In an electrical heating appliance, the combination of a supporting frame having a central dependin hub-like supporting element provided wit a plurality of contacts, spaced resiliently and yieldingly positioned peripheral contacts, and spaced radially extending self-sustaining resistance heating elements having integral terminal portions more highly conductive than the body portions and each mounted in mechanically and electrically operative position between one of said hub contacts and one of said yielding peripheral contacts through butt-end engagement between said contacts and the ends of said heating elements.

13. In an electrical heating appliance,the combination with a frame having an upper plate-like support provided with a central hub and ribs radiating therefrom, a plurality of contacts mounted on said frame adjacent the periphery thereof, a bridging connection carried by said hub portion and provided with a plurality of recessed contact portions, and self-sustaining resistance heating elements maintained in operative position by and between pairs of said peripheral and hub contacts.

14. In an electrical heating appliance, the combination with a frame having an upper plate-like support provided with a central hub and ribs radiating therefrom, a plurality of contacts mounted on said frame adjacent the periphery thercof, a bridging connection carried by said hub portion and provided with a plurality of recessed contact portions, and self-sustaining resistance heating elements maintained in operative position by and between pairs of said peripheral and hub contacts, the heat producing portions of said heating elements being substantially wholly exposed through the openings in said plate between said ribs.

15. In an electrically heated appliance, in combination with a frame having a central hub portion, a plurality of connecting pieces mounted adjacent said hub portion and insulated from each other, each of said connecting pieces being provided with contact portions, spaced resilient contacts mounted on peripheral portions of said frame, and substantially radially extending self-sustaining resistance heating elements yieldingly mounted, in electrical association with said central and peripheral contacts.

16. In an electrically heated appliance, in combination with a frame having a central hub portion, a plurality of connecting pieces mounted adjacent said hub'portion and insulated from each other, each of said connecting pieces being provided with contact portions, spaced resilient contacts mounted on peripheral portions of said frame, and substantially radially extending self-sustaining resistance heating elements yieldingly mounted in electrical association with said central and peripheral contacts, and terminals associated with said peripheral contacts and arranged to permit connection of groups ofsaid heating elements and their contacts in series or in parallel arrangement.

17. In combination in an electrically heated apparatus, a support, a frame removabl mounted on said support, contacts carrie b said frame below the upper edge thereo certain of said contacts being yieldable, and a self-supporting resistance heating element detachably held in yielding frictional engagement with said contacts through pressure exerted on an end of said heating element in the direction of its axis.

18. In combination in an electrically heated apparatus, a support, a frame removably mounted on said support, contacts carried b said frame below the upper edge thereo certain of said contacts bein yieldable, and a self-supportin resistance heating element detachably hel in yielding frictional engagement with said contacts, said Spaced opposed portions provided with heating element being mechanically and electrically mounted in operative position wholly through yielding butt-end engagement with said contacts.

19. In an electrically heated appliance, a support, an apertured frame removably mounted on said support, contacts carried by said frame, certain of said contacts being yieldable, and a self-supporting resistance heating element detachably held in yielding frictional engagement with said contacts,

alined recesses, conductive terminals supported on said frame and having contact portions adapted to occupy positions in substantial alinement with the recesses in the opposed iwall portions, one of said terminals biasing its contact portion toward the contact'portion of an opposed terminal, and a resistance heating elementrdisposed beneath said topjplate with its terminal portions extending into.opposed recesses in said depending wall portions and yieldingly mounted in electrically and mechanicall operative position through butt-end engagement between said terminalsand said heating element.

21. In an electrical heating appliance, in

combination with a support, terminals carried thereby, a supporting frame removably mounted on said support and having termi'nals detachably cooperative with those of said support, contacts carried by said frame at the under side thereof and connected to said terminals, certain of said contacts being I yieldable, and self-sustaining detachable resistance heating elementsmounted in operative position between pairs of said contacts, and a yieldable one of said contacts serving to maintain forcible and yielding engagement with the ends of said heating elements.

22. In an electrical heating appliance, in combination with a support, terminals carried thereby, a supporting frame removably mounted on said support and having terminals detachably cooperative with those of said support, one of said terminals on said support and a corresponding terminal on the frame being of distlnctive shape to insure the same definite positioning of said frame on support at all times, contacts carried by said frame at the underside thereof and connected to said terminals, certain of said contacts being yieldable, and self-sustaining detachable resistance heating elements mounted in operative position between pairs of said contacts, and yieldable ones of said contacts serving to maintain forcible and yielding engagement with the ends of said heating elements.

23. In an electrical heating appliance, in combination with a support, a depending housing carried thereby, a frame removably mounted on said support, a resistance element mounted on the under side of said frame, a heat reflector detachably positioned beneathsaid heating elements, and a heat in-- sulating element carried by said frame and positioned adjacent the under side of said reflectorl 24. In an electrical heating appliance, in combination with a support, a frame removably mounted on said sup ort, a resistance element mounted on said rame, a heat reflector detachably supported by said frame and positioned beneath said heating element and removable with the frame, and a heat insulating element carried by said frame and positioned adjacent the under side of said In witness whereof I afiix my signature