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Publication numberUS3870861 A
Publication typeGrant
Publication dateMar 11, 1975
Filing dateMar 7, 1974
Priority dateMar 7, 1974
Publication numberUS 3870861 A, US 3870861A, US-A-3870861, US3870861 A, US3870861A
InventorsWerych Ewald R
Original AssigneeSola Basic Ind Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electric hot plate heating unit with a ceramic cover
US 3870861 A
A hot plate cover of ceramic is used to cover an in-situ vacuum molded heating element. The cover has a dependent flange therearound which is positionable over the open top of the heating element when the cover is in position thereon. The inner faces of the flange contain indentations which receive resilient latches of the heating element assembly to retain the cover in position.
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Description  (OCR text may contain errors)

I Umted States Patent 1191 1111 3,870,861 Werych 1 Mar. 11, 1975 [541 ELECTRIC HOT PLATE HEATING UNIT 2,538,567 1/1951 Jones 219/454 WITH A CERAMIC COVER 2,570,975 10/1951 Ostcrheld 219/459 2,659,295 11/1953 Soccoli 99/339 Inventor: ald W ych, Elm Gro e, W1s. 2,978,564 4/1961 Blanding et a1 219/260 x 3,047,702 7 1962 L f b 1.. 219 464 [73] Ass1gnee: 2211a Baslc lnanstnes, lnc., 1466997 9x969 i 'i gg X lwaukee 3,613,177 10 1971 22 Filed: Man 7 1974 3,733,462 5/1973 Bouchard C1111. 219/464 [2H Appl' 449345 Primary Examiner-Vo1odymyr Y. Mayewsky Attorney, Agent, or Firm-Smythe & Moore [52] U.S. Cl 219/459, 99/339, 99/447,

24/73 B, 219/454, 219/462, 219/464 [57] ABSTRACT [51] Int. Cl. H05b 3/68 [58] Field of Search 219/454, 455, 456, 457, Plate of 18 used 219/458 459 460 461 462 463 s1tu vacuum molded heatmg element. The cover has a 5 24773 dependent flange therearound which is positionable over the open top of the heating element when the [56] References Cited cover is in position thereon. The inner faces of the flange contain indentations which receive resilient UNITED STATES PATENTS latches of the heating element assembly to retain the v over in position 1,778,884 10/1930 Bressan 319/463 2,513,733 7/1950 Morris 219/464 X 4 Claims. 7 Drawing Figures 1 ELECTRIC IIOT PLATE HEATING UNIT WITH A CERAMIC COVER The present invention relates to a surface heating unit and, more particularly, to the mounting of an electrically heated hot plate on the top of an enclosure.

One form of a surface heating unit comprises a hot plate such as used in a laboratory, home or office. Such a hot plate has a housing or enclosure with a surface heating unit. One form of a surface heating unit comprises a ceramic member having a heating element embedded therein and constructed to have a low thermal mass to enable the unit to heat up in a very short period of time. Since the heating top plate is of ceramic construction, certain obstacles are encountered in securing the top plate to an enclosure which is generally of a metal or plastic construction. Previous proposals for mounting such top plates on an enclosure have been unsatisfactory since they were either unduly complicated in structure or were not reliable since they brought about destruction or damage to the top plate after a period of use.

One of the objects of the present invention is to provide an improved structure for retaining a ceramic top plate upon an enclosure of an in-situ molded surface heating unit.

According to one aspect of the present invention, a surface heating unit may be provided having means to define an enclosure having an open top with resilient latch means at the top edges of the enclosure. The heating element may be an in-situ molded insulating or refractory body with the heating coils embedded therein. Aceramic top plate is positionable upon the enclosure open top and has a dependent flange therearound. There are indentations in the flange to receive the latch means when the top is in position on the enclosure with the heating unit whereby the top plate is retained thereon.

Other objects, advantages and features of the present invention will become apparent from the accompanying description and drawings, which are merely exemplary.

In the drawings:

FIG. 1 is a front elevational view of a surface heating hot plate with a portion shown in section;

FIG. 2 is an overall perspective view of the top plate partially in section;

FIG. 3 is a top plan view of the heating assembly and top plate with a portion of the top plate broken away;

FIGS. 4A, B and C are sectional fragmentary enclarged views of a portion of the top plate and heating unit assembly showing the manner in which the top plate is positioned upon the enclosure and then retained in position; and

FIG. 5 is a schematic perspective of the heating unit enclosure.

Proceeding next to the drawings wherein like reference symbols indicate the same parts throughout the various views, a specific embodiment of the present invention will be described in detail.

In FIG. 1 there is indicated generally at what is commonly known as a laboratory hot plate incorporating the present invention. Housing or base 11 has mounted thereon a heating assembly 12. The base 11 is of a type known in the art and can be provided with switches, controls and dials to provide accurate and precise control over the temperature to which the top plate unit may be heated and also to automatically control the duration of time the plate remains at a selected temperature.

Heating unit assembly 12 has a rectangular box 13 (FIGS. 1, 5) with inwardly tapering faces or sides 14 which define an open top 15. The upper edges 16 of each of the enclosure faces 14 are provided with a latch means 17. The latch 17 is a resilient member extending along a face 14. Latch 17 can be moved inwardly as shown in step B of FIG. 4.

The top plate 18 can be made of suitable ceramic, such as shatterproof glass which will resist thermal shock, chemical corrosion and discoloration.

The top plate 18 has downwardly extending flanges or sides 19 which in the form shown are tapered outwardly. On the inner face of each of at least two of the flanges, there is an elongated slot or indentation 20 for receiving a mating latch tab or extension 17 of box 13.

The heating unit 22 can be composed of coiled heating wire element 23 which is in-situ molded into the inorganic fiber body 24. The heating unit 22 can be made by a vacuum molding process as described in copending Application Ser. No. 371,752, filed June 20, 1973. One example of suitable material is described in US. Pat. No. 3,500,444 and No. 3,500,464.

The problem of assembly and of securing the top plate 18 to the enclosure 13 is eliminated according to the present invention since, as illustrated in FIGS. 4A, B and C, the top plate is mounted by merely positioning the flanges over the open end of the enclosure as shown in FIG. 4A. The top plate 18 is then moved downwardly in the direction of the arrow 21 to cam the latch tab 17 inwardly as shown in FIG. 43 until the top plate 18 is in its intended position as shown in FIG. 4C. At this point the sloping surfaces of the hot plate flange and the faces of the enclosure conform, and the tab 17 is urged into the indentation 20 because of the inherent spring force of the latch.

As can be seen in FIG. 3, the latches are in the form of a sheet or plate and the tabs are elongated so as to provide a substantial length of securing surface between the latches on all of the faces of the enclosure and the respective indentations.

While the embodiment has been described with an enclosure and top plate which has a rectangular transverse section, it should be born in mind that the enclosure may have other cross sections such as circular or polygonal, and the hot plate may have corresponding sections. The latches would then be positioned and shaped to conform to the cross section of the respective enclosures.

Thus, it can be seen that the present invention has provided a simple and effective arrangement for attaching a ceramic top plate to the top of an enclosure which may be of metal, plastic, or other suitable material. No special tools or skills are required for the assembly, and the danger of cracking, chopping, or breaking the ceramic top plate are virtually eliminated.

It will be'understood that changes in various details of construction and arrangement of parts may be made without departing from the spirit of the invention except as defined in the appended claims.

What is claimed is:

1. In an electric hot plate heating unit, the combination of means defining an enclosure having a bottom and sides, electrical heating and insulating means ar-, ranged in said enclosure, latch means at the top edges of said enclosure, a thermally conductive top plateheating surface unit positionable in heat conductive position over said heating and insulating means, said top plate unit having depending flange means there-around positionable over the top of said enclosure and said heating and insulating means, there being indentations in the inner faces of said flange means to receive said latch means when said top plate is in position on said enclosure and heating and insulating means whereby said top plate is retained thereon.

2. In an electric hot plate heating unit as claimed in claim 1 wherein said latch means is resilient and has a portion projecting outwardly of said enclosure whereby positioning the top plate downwardly on the enclosure will cam the projecting portion inwardly until said latch is urged into said indentations upon said top plate reaching its intended position.

3. In an electric hot plate heating unit as claimed in claim 1 wherein said electrical heating means is in-situ molded in said insulating means and said heating and insulating means is carried therein. 5

4. In an electric hot plate heating unit as claimed in claim 1 wherein said latch means comprises a plurality of resilient latches on the faces of said enclosure with each latch means having a portion projecting laterally of said enclosure and adapted to engage indentations in said top plate flange.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1260252 *Apr 3, 1917Mar 19, 1918Philip F ApfelElectric heater.
US1778884 *May 17, 1927Oct 21, 1930Electro Thermal Unit CompanyElectric heating unit
US2513733 *Jun 28, 1947Jul 4, 1950Morris Vergil JFoot warmer
US2538567 *Jan 3, 1947Jan 16, 1951Jones George MVessel for pressure cooking
US2570975 *Jul 27, 1946Oct 9, 1951Mcgraw Electric CoElectric heating element
US2659295 *Mar 17, 1952Nov 17, 1953Soccoli Dom DToast warming attachment for electric toasters
US2978564 *Dec 31, 1958Apr 4, 1961Corning Glass WorksElectric hot plate
US3047702 *Oct 3, 1958Jul 31, 1962Lefebvre Fredrick LPlate heater
US3466997 *Mar 8, 1967Sep 16, 1969Kentucky Fried Chicken CoChicken frying equipment
US3613177 *Jul 27, 1970Oct 19, 1971Corning Glass WorksAnchoring clip for mounting appliances
US3733462 *Jan 11, 1972May 15, 1973Raytheon CoHeating element for flush top ranges
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3936660 *Sep 30, 1974Feb 3, 1976Fluoroware Systems CorporationHot plate
US4004130 *Oct 23, 1975Jan 18, 1977Fluoroware Systems CorporationHot plates
US4195560 *Jul 11, 1977Apr 1, 1980Sunbeam CorporationElectric crepe maker
US4278877 *Aug 2, 1979Jul 14, 1981General Signal CorporationElectrical heating unit with flattened embedded heating coil
US4321459 *Mar 7, 1980Mar 23, 1982Nichias CorporationElectrical heating molded-element comprising inorganic fibers
US4617450 *Mar 22, 1983Oct 14, 1986Bulten-Kanthal GmbhStable at high temperatures
US4634841 *Jun 18, 1985Jan 6, 1987Laughrey James CCover for cooking stove heating element
US4861969 *Mar 18, 1988Aug 29, 1989E.G.O. Elektro-Gerate Blanc U. FischerElectric hotplate, apparatus and method for fitting a cover plate thereto
US6297482Jul 26, 2000Oct 2, 2001Maytag CorporationCeramic-based downdraft cooktop having angled front face portion
US6501053Sep 28, 2001Dec 31, 2002Maytag CorporationControl system for an appliance cooktop
U.S. Classification219/465.1, 99/447, 99/339
International ClassificationH05B3/74, H05B3/68
Cooperative ClassificationH05B3/748
European ClassificationH05B3/74R
Legal Events
Aug 2, 1990ASAssignment
Effective date: 19900731
Aug 2, 1990AS02Assignment of assignor's interest
Effective date: 19900731