US 2664492 A
Description (OCR text may contain errors)
Dec. 29, 1953 K, FISCHER 2,664,492
HEATING PLATE STRUCTURE Filed Aug. 24, 1949 Patented jeo. 29, 195.3
UNITED STATES PATENT OFFICE Claims priority, application Germany February 9, 1949 5 Claims. (C1. 219-37) This invention relates to certain improvements in electric heating plate structures and stove frames therefor, of the type in which the heating plate includes an outer eaves rim adapted to prevent overowing cooking substances from getting to the underside of the heating plate in which the heating elements are embedded.
As is well known, electric heating plates in operation are exposed to very intensive corrosion stresses which especially act upon the eaves rim which in most instances is extended downwards to a low level.
It is the object of the present invention substantially to reduce the danger of corrosion and to provide a heating plate which in addition to a good appearance offers advantages when it is installed in electric stove frames.
With this object in View, according to the present invention the eaves rim is provided as a sheet metal ring of a corrosion-proof material ein bedded in the outer rim of the cast iron plate, in the casting process.
According to a further feature of the invention, my novel heating plate can be iitted in a particularly appropriate manner in a suitably shaped stove frame with upwardly directed rim of the circular aperture provided in the stove plate for reception of the heating plate by extending the said eaves rim in such a way in a radial direction, that it reaches beyond the upwardly directed rim of the stove plate, thus overlapping the air gap between the outer edge of the heating plate and the inner edge of the said circular aperture which hereinafter is termed heating hole for the sake of brevity.
Further objects and features of the invention will be seen from the following detailed description in connection with the accompanying drawing, showing by way of example and purely schematically some embodiments of the invention and in which:
Figs. l to '7 show each a vertical fragmentary section through the part of a stove plate adjacent to the edge of a heating hole, and the outer rim of a heating plate, i. e.,
Figs. 1 and 2 relating to conventional designs of heating plates,
Figs. 3 to 5 and 9 relating to various embodiments of heating plates according to the invention, with cast-in corrosion-resistant sheet metal ring,
Fig. 6 is a section on the line VI-VI in Fig. 8,
Fig. '7 is a section on the line VII-VII in Fig. 8,
Fig. 8 is a perspective view of the upper part oi a stove, and
Fig. 10 is a perspective view of another embodiment.
Similar reference numerals denote similar parts in the different views.
Referring now to the drawings in greater detail, it will be seen that l is the stove plate, 2 is a heating hole provided in the stove plate, 3 is the heating plate, 4 is a downwardly projecting rim which is made in one piece with the heating plate 3 and serves as an eaves rim in the conventional heating plates. It will be seen from Fig. 1, that between the inner` edge of the heating hole 2 and the outer edge of the heating plate 3 there is left an air gap into which overilowing cooking liquid may easily get. `Owing to the considerable heat expansions of the hot heating plate in relation to the cold stove plate this air gap cannot be dispensed with. Moreover, the rim 4 would be subject to corrosion if it would only partly lie against the rim of the heating hole.
It has been proposed already to arrange the heating plate 3 above the stove plate l, in the manner shown in Fig. 2, in such a way that its eaves rim 4 projects radially beyond the upwardly turned rim 5 of the heating hole which in this case has a smaller diameter than the cast plate 3. Owing to the large difference in height between the upper edge of the heating plate 3 and the surface of the stove plate I this arrangement implies the danger that a cooking pot of a larger diameter moved out of the center of the heating plate will overturn, while with the usual small level difference (compare e. g. h1 in Fig. 1) it would only tilt a bit, Without turning over.
Referring now to my novel design as shown in Fig. 3, it will be seen that in this case a sheet metal ring 6 consisting of a corrosion-resistant and preferably non-rusting steel (e. g. V2A steel) is cast in the outer rim of the heating plate 3 again consisting of cast iron, for bridging the air gap between the outer rim of the heating plate and the edge 5 of the heating hole 2. The outer rim 8 of the sheet metal ring 5 is downwardly bent, thus forming a vertical eaves rim with a very sharp eaves edge which prevents the cooking liquid from adhering and owing 01T inwardly, i. e. towards the center of the heating plate.
Fig. 4 shows another modification of a cast-in sheet metal ring yE, having a substantially U- shaped cross section. The outer eaves rim 8 corresponds in shape to that as per Fig. 3, while the middle shank of the U is Slightly downwardly inclined in an outward direction, i. e. away from the center of the heating plate. 'The sheet metal ring Gwaccordingto Fig. 4 differs substantially sides, in cast iron walls embracing it from Ybe-x low U-fashion and all having about the same wall thickness which again correspondslto .theawall thickness of the heating plate. Bythis embedding method every danger of corrosion is eliminated and the sheet metal ringeisgetlsairllorefslielyv protected against cracks by heat expansion ,than in the embodiment as per Fig. "Itishould be noted that the heat expansion of the plate and of the sheet metal ring are in a proportion of about 2:3; hence also with a view tothe con- `tinuously changing vtensile vand compressive stresses when heating and cooling the plate. .and t l.thefring the collar-shaped inner rim la willstand substantially higher stresses than. the flat form according to Fig. 3. :Also the. slightdownward inclination of the middle or bridge portion ofthe sheet4 metal .ring in an outward direction isV ad- .,vantageous in order to lead oil the overflowing cookingliquids from the heating plate and the .heating holetowards the outside. instead of the U-shaped prolelF-ig. 9) .it would also be possible to chooseV a semicircular profile of the sheet metal `ringnwhich oiers advantages in regardto the manufacture. .In my novel form of the eaves ..rng.6, 3, 'laasper Fig. 4 the conventional eaves -rim'd of thecastriron heating plate extending downwardlyto a very low point can be dispensed 1 with lor at leastmade substantially shorter.
-Althoughmy novel design oi the eaves rim with cast-insheet metalring of non-rusting steel 4offersspecial` advantages inasmuch as it eliminates the -danger of corrosion for the rim ofthe cast1iron plate, additional advantageswill be vvsecured in.` connectionwitnstove ,plates whose heating .holes have upwardly turned rims 5.
Owing tothe fact that the sheet .metal rings `li,
which-are made with a suitable width, completely coverthe annular gap 2 between the inner edge annular, 5 `ofthe stovelhole, my. novel` sheet -metal ring 6 safeguards the heating plate, and the vinteriorrof` the stoveagainst the entering ofover flowing food. This safety factor-canfbe further :increased by providing-.between the upwardly turned edge 5-offthel cooking hole and theplane :of-.thestove plate i a step 'i2 l(Fig. i)v leading upy Awards to the edge-of the heating hole-and adapted a tQdead-the Vowing down cooking liquid away yffrom the heating hole immediatelyincase ofV a v `:brisk overilowing sothat no accumulation of :,:liquid -will take placey in the vicinity or" said edge.
i It, is also contemplated within the purviewof r this yinvention `to have the-lower edge of the outer rim l8-.andv s0 the whole heating plate Sseat onthe stove-plate i. `In this case vthe outerrim maybe provided with a packing rim I Lelastically. seated jags (Fig. or teeth suitable for leading away the drops, or by bending the lower rim inwardly and outwardly in a wave or zig zag form, in the manner which is well known, e. g., from round cake forms, so that no illustration will be necessary in this respect.
.Advantageously the rsheet: metal ring. t is ar- Y ranged in such a way in relation tothe useful upper surface of the heating plate 3 that the level of the surface of the sheet metal ring lies deeper than the surface or" the heating plate Japproximately by the thickness of the heating v plate.
Figs. 6,' "I, and S will exemplify the mounting of :l afheatingplateaslper Fig. 1i in a specially shaped stove platawhose shape will best be seen from Y,fthe two sectional views in Figs. 6 and 7. The
surface lli of the stove plate l is slightly inclined ,towardsall sides from the upwardly bent edge 5 of the stove hole to an elevated border which in Fig. Tis relatively narrow, as indicated at lbut in Figli is somewhat broader, as shown lat i6.
At the lowest points Il of the 'surface it inthe immediate vicinity of the border l5, or iii, fany -overflowing cooking liquid will be collected and ycan beV easily wiped away by the housewife, or
as new and desire to secure b operator, while any overflow into the annular gap 2 between the rim i3A of the heating plate and the upwardly bent stove hole rim. 5 is prevented. This is an important advantage of my. novel combination oi a specially designed heating plate with a specially designed stove plate.
As various possible embodiments might be made of the aboveinvention, and as various changes might be made in the embodiments `aboveset forth, it is to` be understood that all matter herein set forth. or-shown inthe vaccompanying drawing is to be interpreted as illustrative and not'in a limiting sense.
`Having thus described my invention, I claim Letters Patent:
l. n an electric heating plate structurey for an opening ina stove plate having an upwardly yturned rim therein, a` cast iron Yheating plate and a sheet ymetal ring of a corrosion-resistant material whose inner border is bent downwards from its-radially projecting portion so as to form a l completely closed annular collar which has substantially the same diameter as theouter edge of the upper surface of the heating plate and is cast Yin the outer rim of said heating plate, said v ring comprising a peripheral eaves edge projecting overthe upwardly turned rim of fthe stove plate, the bending point between said collarand said radial portion being rounded oir".
2-. in an electric heating plate structure, a cast iron heating plate and a sheet metal ring yof` a corrosion-resistant material whose inner border `is bent downwards from its radially projecting 1 portion so as to form a completely closed annular collar which is cast in the outer rim oi said heatingplate so, as to be completely embedded at its lower edge and at its lateral faces by cast walls fof saidcast ironheating platehaving substantially the same wall thickness on the lower, inner, and outer sides of said collar, said ring comprising a peripheral eaves edge.
:ong the-stoveplate, vas'per Fig. 5. This, however, in general is undesirable since the voverflowing liquid owing to capillary effects tends to extend 3.; In an velectric heating plate structure, a cast iron heating plate and a sheet metal ring ofV a Acorrosion,-resistant material whose inner border -byproviding the rim-8of Fig. .4, whether seated f onthestove plate or spacedtherefrom, with sharp is bent downwards from its radially projecting Vportion so asto form a completely closed annular lcollar which is cast in the outer rim of said heatf ,ing plate so asv to be, completely embedded at its lower edge and at its lateral' faces bycast Walls of said cast iron heating plate having substantially the same wall thickness on the lower, inner, and outer sides of said collar, said ring comprising a peripheral eaves edge, the upper edge of said eaves ring being seated lower than the upper edge of the heating plate by an amount corresponding to the thinnest Wall thickness of the recessed heating plate.
4. In an electric heating plate structure for an opening in a stove plate having an upwardly turned rim therein, a cast iron heating plate and a sheet metal ring of a corrosion-resistant material cast in the outer rim of said heating plate, said ring having an inner portion which is bent downwards from its radially projecting portion to form a completely closed annular collar, and having a slight downward slope towards its periphery which is formed with a downwardly turned collar including an eaves edge projecting over the upwardly turned rim of the stove plate.
5. In an electric heating plate structure, a cast iron heating plate and a sheet metal ring of a corrosion-resistant material whose inner border is bent downwards from its radially projecting portion so as to form a completely closed annular collar which is cast in the outer rim of said heating plate so as to be completely embedded at its lower edge and at its lateral faces by cast walls of said cast iron heating plate, said ring comprising a peripheral eaves edge.
References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,257,106 Parkhurst Feb. 19, 1918 1,699,737 Hicks Jan. 22, 1929 1,700,543 Pierson Jan. 29, 1929 1,715,692 Backer June 4, 1929 2,029,573 Knapp et al. Feb. 4, 1936 2,176,382 Smith Oct. 17, 1939 FOREIGN PATENTS Number Country Date 62,663 Norway July 8, 1940 241,189 Switzerland June 17, 1946 252,708 Switzerland Oct. 16, 1948 363,362 Italy Oct. 3, 1938 446,410 Great Britain Apr. 29, 1936 463,007 Great Britain Mar. 19, 1937