US3885128A - Glass-ceramic plate heating unit cast-in heat spreader - Google Patents
Glass-ceramic plate heating unit cast-in heat spreader Download PDFInfo
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- US3885128A US3885128A US484421A US48442174A US3885128A US 3885128 A US3885128 A US 3885128A US 484421 A US484421 A US 484421A US 48442174 A US48442174 A US 48442174A US 3885128 A US3885128 A US 3885128A
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- glass
- ceramic plate
- plate
- heating element
- underside
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- 239000002241 glass-ceramic Substances 0.000 title claims abstract description 57
- 238000010438 heat treatment Methods 0.000 title claims abstract description 56
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 16
- 229910052751 metal Inorganic materials 0.000 claims abstract description 12
- 239000002184 metal Substances 0.000 claims abstract description 12
- 230000008878 coupling Effects 0.000 claims abstract description 8
- 238000010168 coupling process Methods 0.000 claims abstract description 8
- 238000005859 coupling reaction Methods 0.000 claims abstract description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052802 copper Inorganic materials 0.000 claims abstract description 7
- 239000010949 copper Substances 0.000 claims abstract description 7
- 238000005058 metal casting Methods 0.000 claims description 15
- 230000002093 peripheral effect Effects 0.000 claims description 3
- 230000001808 coupling effect Effects 0.000 claims description 2
- 238000005266 casting Methods 0.000 description 6
- 239000011521 glass Substances 0.000 description 6
- 239000006112 glass ceramic composition Substances 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 241000125205 Anethum Species 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000010411 cooking Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000007480 spreading Effects 0.000 description 2
- KEQXNNJHMWSZHK-UHFFFAOYSA-L 1,3,2,4$l^{2}-dioxathiaplumbetane 2,2-dioxide Chemical compound [Pb+2].[O-]S([O-])(=O)=O KEQXNNJHMWSZHK-UHFFFAOYSA-L 0.000 description 1
- 239000006095 Cer-Vit Substances 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 239000002196 Pyroceram Substances 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 230000005574 cross-species transmission Effects 0.000 description 1
- 230000000994 depressogenic effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 229940020445 flector Drugs 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 239000005337 ground glass Substances 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002470 thermal conductor Substances 0.000 description 1
- 239000000037 vitreous enamel Substances 0.000 description 1
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
- F24C15/00—Details
- F24C15/10—Tops, e.g. hot plates; Rings
- F24C15/102—Tops, e.g. hot plates; Rings electrically heated
- F24C15/105—Constructive details concerning the regulation of the temperature
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/68—Heating arrangements specially adapted for cooking plates or analogous hot-plates
- H05B3/74—Non-metallic plates, e.g. vitroceramic, ceramic or glassceramic hobs, also including power or control circuits
- H05B3/748—Resistive heating elements, i.e. heating elements exposed to the air, e.g. coil wire heater
Definitions
- ABSTRACT A glass-ceramic plate surface heating unit has a high thermal conductivity layer such as aluminum or copper cast in a recess formed on the underside of the plate, a metal sheathed electrical resistance heating element with an underlying reinforcing member is cast into the high conductivity layer, so that the said layer serves both as a mechanical and thermal coupling means between the heating element and the plate as well as a heat spreader means across the plate,
- the underside of the plate is shown with a plurality of cavities so as to increase the area of contact between the high conductivity layer and the glass-ceramic plate.
- the invention relates to glass-ceramic plate surface heating units or cooktops with a metal sheathed heating element cast into a heat spreading layer on the underside of the plate.
- Another difficulty encountered in glass-ceramic plate heating units is the rather poor quality of thermal conductivity through the glass-ceramic material.
- Such material is used widely in other arts as a thermal and electrical insulating material. rather than as a thermal conductor in the present invention. Heat does not readily diffuse laterally through the glass-ceramic plate, and during a cooking operation heat will flow to the utensil only near the point of contact. The remainder of the heated area may become very hot.
- the principal object of the present invention is to provide a glass-ceramic plate surface heating unit or cooktop with a cast-in heat spreader plate which also serves as a mechanical and thermal coupling means for the heating element.
- a further object ofthe present invention is to provide a glass-ceramic plate heating unit or cooktop of the class described with an enlarged area of contact between the cast-in heat spreader plate and the glassceramic plate.
- the present invention in accordance with one form thereof. relates to a solid plate surface heating unit comprising a glass-ceramic plate having a recess formed on the underside thereof. the recess being substantially filled with a high conductivity cast-in heat spreader layer.
- a metal sheathed electrical resistance heating element with a reinforcing member of open framework is fastened across the underside of the heating element that is in turn cast in the said heat spreader layer so that the layer serves both as a mechanical and thermal coupling means between the heating element and the glass-ceramic plate. as well as a heat spreading means of good thermal conductivity across the heated area of the plate.
- FIG. 1 is a fragmentary. cross-sectional. elevational view through about one-half of a solid glass-ceramic plate surface heating unit embodying the present invention, showing an aluminum or copper casting held in the underside of the glass-ceramic plate. with the heating element confined therein.
- FIG. 2 is a bottom plan view of the glass-ceramic plate of FIG. 1 showing a pattern ofa plurality of cavities formed on the underside of the glass-ceramic plate so as to increase the surface area of contact between the heat spreader casting and the glass-ceramic plate.
- FIG. 1 there is shown a cross-sectional, elevational view of a solid plate surface heating unit 10 having a thin glass-ceramic plate 12 which is a molded part of generally circular configuration having an inverted pan-shape by virtue of a recess 14 created on the underside of the glass-ceramic plate due to the presence of a down-turned peripheral wall 15.
- this glass-ceramic plate is not a simple plate of uniform thickness throughout, as in most. if not all. glass-ceramic cooktops sold widely on the market today. While this invention is shown incorporated in a single solid plate surface heating unit, it should be understood that it is equally applicable in a cooktop having a plurality of heated areas, where each heated area would have its own heat spreader layer 16.
- This glass-ceramic material is electrically insulating and thermally transmissive as well as being highly wear and thermal shock resistant, and resistant to the physical and chemical attacks of foods and liquids which may come in contact with the plate at relatively high temperatures. While the term glass-ceramic material or crystalline glass material is used throughout. it should be understood that this invention encompasses other materials with similar characteristics, such as quartz, high-silica glass, high-temperature glasses and different ceramic materials.
- the present invention contemplates the casting of an aluminum or copper layer 16 within the recess 14 on the underside of the glass-ceramic plate 12.
- a sub-assembly of a metal sheathed electrical resistance heating element 18 of spiral configuration is first staked or otherwise mounted on a reinforcing support 20 of open framework. This sub-assembly is placed in contact with the molten metal 16 such that as the metal solidifies the heating element and a portion of the reinforcing framework 20 will be cast into the heat spreader layer 16.
- the sheathed heating element 18 is shown with two vertically-arranged electrical terminals 21 and 22 for joining the heating element in an electrical circuit.
- a reflector pan 26 of rather deep configuration is positioned beneath the heating unit 18 and reinforcing framework 20.
- the upper perimeter of the reflector pan 26 has an outwardly extending ledge 28 on which the supporting framework 20 is seated.
- a J-bolt 32 is hooked to the reinforcing frame 20 at its upper end 54, while the lower threaded end of the .l-bolt extends through an opening 36 in the bottom of the reflector pan 26 and a nut 38 is tightened on the bolt until the surface unit is tightly held in the reflector pan 26.
- This temperature-limiting means comprises a temperature sensor 42 in the form of an elongated bulb which is positioned outside the outermost coil of the heating element 18 and is positioned on the reinforcing framework and cast in the heat spreader layer 16.
- This sensor 42 is a bulb-like member that is filled with a high temperature thermostatic fluid such as sodium potasium (NaK) or the like.
- the sensor communicates with a temperature responder 44 by means of a capillary tube 46, which is shown diagrammatically as a long dash line.
- This temperature responder 44 is a singlepoint, temperature-limiting switch or thermostat that is set at a critical temperature of about 1250F.
- This temperature responder 44 would include switch means (not shown) in a series circuit with the heating element 18 such that if the critical temperature of the heat spreader casting would be reached the power circuit to the heating element 18 would be broken and the heating element de-energized.
- a similar arrangement is utilized in the Hurko US. Pat. No. 3,622,754.
- This solid plate surface heating unit 10 is shown mounted in a cooktop 50 by means of a depressed circular ledge 52 that encircles a cut-out opening 54. It is best to provide some means for holding the surface unit 10 down in place, and this function is provided by a trim ring 56 which has a transverse T-shaped crosssection with a first vertical shank section 58 which is insertable into the narrow gap between the periphery of the heating unit 10 and the vertical side 60 created by the recessed ledge 52. The upper edge ofthe vertical shank 58 is provided with a folded-over crown 62 which overlies both the edge of the cooktop 50 and the edge of the glass-ceramic plate 12.
- Releasable means must be provided for holding the trim ring 56 in place.
- a series of widely spaced clip members 66 are attached to the shank portion 58 of the trim ring 56 at widely spaced positions around the trim ring.
- Each clip member 66 is of thin spring material of narrow width, and at its upper end it is provided with an offset finger 68 which is adapted to extend through a mating slot 70 formed in the shank portion of the trim ring 56.
- the only way to insert the finger 68 through the slot 70 is to remove the surface unit 10 from the cooktop 50 and insert the fingers at a generally perpendicular angle with respect to the shank portion 58 of the trim ring, and then pivot or lower the clip member down against the side of the shank portion, as is best seen in FIG. 1.
- Each clip member 66 is generally of Z-shape in side view having a generally vertically upper flange 74, a generally horizontal mid-portion 76 and a wide V-shaped lower portion 78.
- This lower V- portion 78 has an apex 80 that is directed generally toward the edge of the ledge 52 of the cooktop 50 to serve as a detent member, such that when the surface unit 10 is lowered onto the recessed ledge 52 of the cooktop 50, the apex 80 tends to engage the innermost edge of the ledge 52 until additional force causes the clip member to spring away from the ledge and then the apex to snap back beneath the ledge to serve as a tight hold-down means.
- a surface heating unit comprising a glass-ceramic plate having recess means formed on the underside thereof, the recess means substantially covering a large area of the plate and being substantially filled with a metal casting of high thermal conductivity such as aluminum or copper that is formed in place, a metal sheathed electrical resistance heating element with a reinforcing member of open framework fastened across the underside of the heating element, the heating element and reinforcing member being partially embedded in the said metal casting, whereby the metal casting serves as both a mechanical and thermal coupling means between the heating element and the glassceramic plate as well as the heat spreader means across the plate.
- a surface heating unit as recited in claim 1 wherein there is a reflector pan positioned beneath the glass-ceramic plate and having a peripheral edge near the top portion of the pan on which the said reinforcing member is seated, and fastening means joining the re flector pan to the reinforcing member, the area of the glass-ceramic plate in contact with the metal casting being provided with a textured surface having a plurality of cavities for increasing the area of contact between these two parts and hence the thermal coupling action.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Electric Stoves And Ranges (AREA)
- Resistance Heating (AREA)
- Baking, Grill, Roasting (AREA)
Abstract
A glass-ceramic plate surface heating unit has a high thermal conductivity layer such as aluminum or copper cast in a recess formed on the underside of the plate, a metal sheathed electrical resistance heating element with an underlying reinforcing member is cast into the high conductivity layer, so that the said layer serves both as a mechanical and thermal coupling means between the heating element and the plate as well as a heat spreader means across the plate. The underside of the plate is shown with a plurality of cavities so as to increase the area of contact between the high conductivity layer and the glass-ceramic plate.
Description
United States Patent [1 1 Dills GLASS-CERAMIC PLATE HEATING UNIT CAST-1N HEAT SPREADER [75] Inventor: Raymond L. Dills, Louisville, Ky.
[73] Assignee: General Electric Company,
Louisville, Ky.
22 Filed: July 1,1974
21 Appl. No.: 484,421
[52] US. Cl. 219/462; 219/457; 219/463; 219/464; 219/530 [51] Int. Cl. 1. H051) 3/68 [58] Field of Search 219/439, 449, 457, 458, 219/459, 461,462,463, 464, 467,530
[56] References Cited UNITED STATES PATENTS 1,924,409 8/1933 Manson 1 219/530 2,152,126 3/1939 Young 219/460 3,519,798 7/1970 Walther 1. 219/439 3,569,672 3/1971 Hurko 219/464 [4 1 May 20, 1975 3,622,754 11/1971 Hurko 219/462 3,632,983 1/1972 Dills 219/.464 3,805,023 4/1974 Waimer et al. 219/464 X 3,816,704 6/1974 Borom et a1, 219/462 Primary Examiner-Velodymyr Y. Mayewsky [57] ABSTRACT A glass-ceramic plate surface heating unit has a high thermal conductivity layer such as aluminum or copper cast in a recess formed on the underside of the plate, a metal sheathed electrical resistance heating element with an underlying reinforcing member is cast into the high conductivity layer, so that the said layer serves both as a mechanical and thermal coupling means between the heating element and the plate as well as a heat spreader means across the plate, The underside of the plate is shown with a plurality of cavities so as to increase the area of contact between the high conductivity layer and the glass-ceramic plate.
3 Claims, 2 Drawing Figures GLASS-CERAMIC PLATE HEATING UNIT CAST-IN HEAT SPREADER BACKGROUND OF THE INVENTION 1. Field of the Invention:
The invention relates to glass-ceramic plate surface heating units or cooktops with a metal sheathed heating element cast into a heat spreading layer on the underside of the plate.
2. Description of the Prior Art:
In order to improve the cleanability of cooktops of domestic ranges as well as built-in countertop cooktops, the standard porcelain enamel cooktop surface with separate electrical heating elements or gas burners has been replaced in certain models of appliances by high resistivity glass-ceramic plates. which are heated by electricity or gas. Such plates are of generally milkwhite. opaque, glass-ceramic or crystalline glass material sold under such trademarks as PYROCERAM. CER-VIT". and HERCUVIT. This glass-ceramic material has a low thermal expansion coefficient, and it has a smooth top surface of almost ground glass finish or texture that presents a pleasing appearance and is also readily cleanable. The continuous top surface prevents the drainage of spillovers underneath the cooktop.
One such electrically heated glass-ceramic cooktop design is shown in US. Pat. No. 3.632.983 of the present inventor. which is also assigned to the assignee of the present invention Present day glass-ceramic surface units and cooktops are less efficient thermally than standard porcelain enamelled steel cooktops having metal sheathed electrical resistance heating elements of spiral configuration. This is mainly because the glass-ceramic material has a high thermal mass. thus a slow thermal response requiring a longer time to heat up and cool down. The heat is stored in the glassceramic plate as well as in the sheathed heating element and in the insulating support block or pad for the heating element. When open coil heaters are used at a spaced distance below the plate there is also a poor thermal coupling between the heater and the glass-ceramic plate. In order to transfer the heat from an open coil heater to the glassceramic plate. the heater has to operate at higher temperatures than otherwise. which creates several problems such as poor efficiency of the system, high heat losses, over heating of components. and high cooktop temperatures. Glass-ceramic cooktops and surface units with open coil heaters also present a safety hazard in the event the glass-ceramic plate is broken and liquids should pass through the crack and contact the open coil heater.
Another difficulty encountered in glass-ceramic plate heating units is the rather poor quality of thermal conductivity through the glass-ceramic material. Such material is used widely in other arts as a thermal and electrical insulating material. rather than as a thermal conductor in the present invention. Heat does not readily diffuse laterally through the glass-ceramic plate, and during a cooking operation heat will flow to the utensil only near the point of contact. The remainder of the heated area may become very hot.
One solution to this problem of low thermal efficiency in glass-ceramic plate heating units is taught in US. Pat. No. 3,622,754 of Bohdan Hurko, which is also assigned to the present assignee. This Hurko patent employs a metal sheathed heating element that is attached to theunderside of a thin composite plate having a core of high thermal conductivity such as copper, silver or aluminum. The composite plate is pressed against the underside of the glass-ceramic plate.
The principal object of the present invention is to provide a glass-ceramic plate surface heating unit or cooktop with a cast-in heat spreader plate which also serves as a mechanical and thermal coupling means for the heating element.
A further object ofthe present invention is to provide a glass-ceramic plate heating unit or cooktop of the class described with an enlarged area of contact between the cast-in heat spreader plate and the glassceramic plate.
SUMMARY OF THE INVENTION The present invention, in accordance with one form thereof. relates to a solid plate surface heating unit comprising a glass-ceramic plate having a recess formed on the underside thereof. the recess being substantially filled with a high conductivity cast-in heat spreader layer. A metal sheathed electrical resistance heating element with a reinforcing member of open framework is fastened across the underside of the heating element that is in turn cast in the said heat spreader layer so that the layer serves both as a mechanical and thermal coupling means between the heating element and the glass-ceramic plate. as well as a heat spreading means of good thermal conductivity across the heated area of the plate.
BRIEF DESCRIPTION OF THE DRAWINGS This invention will be better understood from the following description taken in conjunction with the accompanying drawings and its scope will be pointed out in the appended claims.
FIG. 1 is a fragmentary. cross-sectional. elevational view through about one-half of a solid glass-ceramic plate surface heating unit embodying the present invention, showing an aluminum or copper casting held in the underside of the glass-ceramic plate. with the heating element confined therein.
FIG. 2 is a bottom plan view of the glass-ceramic plate of FIG. 1 showing a pattern ofa plurality of cavities formed on the underside of the glass-ceramic plate so as to increase the surface area of contact between the heat spreader casting and the glass-ceramic plate.
DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to a consideration of the drawings and in particular to FIG. 1, there is shown a cross-sectional, elevational view of a solid plate surface heating unit 10 having a thin glass-ceramic plate 12 which is a molded part of generally circular configuration having an inverted pan-shape by virtue of a recess 14 created on the underside of the glass-ceramic plate due to the presence of a down-turned peripheral wall 15. In other words; this glass-ceramic plate is not a simple plate of uniform thickness throughout, as in most. if not all. glass-ceramic cooktops sold widely on the market today. While this invention is shown incorporated in a single solid plate surface heating unit, it should be understood that it is equally applicable in a cooktop having a plurality of heated areas, where each heated area would have its own heat spreader layer 16.
This glass-ceramic material is electrically insulating and thermally transmissive as well as being highly wear and thermal shock resistant, and resistant to the physical and chemical attacks of foods and liquids which may come in contact with the plate at relatively high temperatures. While the term glass-ceramic material or crystalline glass material is used throughout. it should be understood that this invention encompasses other materials with similar characteristics, such as quartz, high-silica glass, high-temperature glasses and different ceramic materials.
It would be extremely difficult to maintain an even temperature distribution across this glass-ceramic plate 12 if it were heated directly by an open coil resistance heating element or a metal sheathed resistance heating element of looped configuration. Heat diffuses very slowly laterally through the glass-ceramic material, and hence. hot spots would be created on the plate surface nearest the areas of contact between the heater and the glass, as well as between the glass and the warped bottom of a cooking utensil. This type of glass cannot exceed an operational temperature of about l300F at any point, hence, the total heat output of a glassceramic surface heating unit would be reduced if the plate is provided with an uneven temperature distribution. In the absence of a temperature-limiting means, the plate would have to be underheated in order to avoid damaging the glass-ceramic plate.
The present invention contemplates the casting of an aluminum or copper layer 16 within the recess 14 on the underside of the glass-ceramic plate 12. Before this metal casting is poured and solidified, a sub-assembly of a metal sheathed electrical resistance heating element 18 of spiral configuration is first staked or otherwise mounted on a reinforcing support 20 of open framework. This sub-assembly is placed in contact with the molten metal 16 such that as the metal solidifies the heating element and a portion of the reinforcing framework 20 will be cast into the heat spreader layer 16. The sheathed heating element 18 is shown with two vertically-arranged electrical terminals 21 and 22 for joining the heating element in an electrical circuit.
A reflector pan 26 of rather deep configuration is positioned beneath the heating unit 18 and reinforcing framework 20. The upper perimeter of the reflector pan 26 has an outwardly extending ledge 28 on which the supporting framework 20 is seated. A J-bolt 32 is hooked to the reinforcing frame 20 at its upper end 54, while the lower threaded end of the .l-bolt extends through an opening 36 in the bottom of the reflector pan 26 and a nut 38 is tightened on the bolt until the surface unit is tightly held in the reflector pan 26.
It is important to limit the operating temperature of the glass-ceramic plate 12 to a temperature below about l300F. This can best be done by introducing a temperature-limiting means to the solid plate surface unit of the present invention such that the power to the heating element 18 is cut off if the temperature of the heat spreader casting 16 rises to a predetermined temperature. This temperature-limiting means comprises a temperature sensor 42 in the form of an elongated bulb which is positioned outside the outermost coil of the heating element 18 and is positioned on the reinforcing framework and cast in the heat spreader layer 16. This sensor 42 is a bulb-like member that is filled with a high temperature thermostatic fluid such as sodium potasium (NaK) or the like. The sensor communicates with a temperature responder 44 by means of a capillary tube 46, which is shown diagrammatically as a long dash line. This temperature responder 44 is a singlepoint, temperature-limiting switch or thermostat that is set at a critical temperature of about 1250F. This temperature responder 44 would include switch means (not shown) in a series circuit with the heating element 18 such that if the critical temperature of the heat spreader casting would be reached the power circuit to the heating element 18 would be broken and the heating element de-energized. A similar arrangement is utilized in the Hurko US. Pat. No. 3,622,754.
This solid plate surface heating unit 10 is shown mounted in a cooktop 50 by means of a depressed circular ledge 52 that encircles a cut-out opening 54. It is best to provide some means for holding the surface unit 10 down in place, and this function is provided by a trim ring 56 which has a transverse T-shaped crosssection with a first vertical shank section 58 which is insertable into the narrow gap between the periphery of the heating unit 10 and the vertical side 60 created by the recessed ledge 52. The upper edge ofthe vertical shank 58 is provided with a folded-over crown 62 which overlies both the edge of the cooktop 50 and the edge of the glass-ceramic plate 12.
Releasable means must be provided for holding the trim ring 56 in place. For this purpose a series of widely spaced clip members 66 are attached to the shank portion 58 of the trim ring 56 at widely spaced positions around the trim ring. Each clip member 66 is of thin spring material of narrow width, and at its upper end it is provided with an offset finger 68 which is adapted to extend through a mating slot 70 formed in the shank portion of the trim ring 56. The only way to insert the finger 68 through the slot 70 is to remove the surface unit 10 from the cooktop 50 and insert the fingers at a generally perpendicular angle with respect to the shank portion 58 of the trim ring, and then pivot or lower the clip member down against the side of the shank portion, as is best seen in FIG. 1. These fingers 68 become captured in place in the slots 70 due to the small clearance between the shank portion 58 and the vertical side 60 of the cooktop edge. Each clip member 66 is generally of Z-shape in side view having a generally vertically upper flange 74, a generally horizontal mid-portion 76 and a wide V-shaped lower portion 78. This lower V- portion 78 has an apex 80 that is directed generally toward the edge of the ledge 52 of the cooktop 50 to serve as a detent member, such that when the surface unit 10 is lowered onto the recessed ledge 52 of the cooktop 50, the apex 80 tends to engage the innermost edge of the ledge 52 until additional force causes the clip member to spring away from the ledge and then the apex to snap back beneath the ledge to serve as a tight hold-down means.
There is a tendency for the metal casting 16 to contract slightly from the glass-ceramic plate 12 as the casting solidifies. This effect can be counterbalanced by providing a pattern of concavities in the glasssurface in the recess 14, as is best seen in the bottom plan view of FIG. 2. This increases the surface area of contact between the metal casting and the glassceramic plate to improve the thermal coupling between these two parts. Other patterns of concavities 85 may be substituted such as a corrugated surface, a pebbled embossed or textured surface.
Modifications of this invention will occur to those skilled in this art, therefore, it is to be understood that this invention is not limited to the particular embodiments disclosed but that it is intended to cover all modifications which are within the true spirit and scope of 5 this invention as claimed.
What is claimed as new and desired to be secured by Letters Patent of the United States is:
1. A surface heating unit comprising a glass-ceramic plate having recess means formed on the underside thereof, the recess means substantially covering a large area of the plate and being substantially filled with a metal casting of high thermal conductivity such as aluminum or copper that is formed in place, a metal sheathed electrical resistance heating element with a reinforcing member of open framework fastened across the underside of the heating element, the heating element and reinforcing member being partially embedded in the said metal casting, whereby the metal casting serves as both a mechanical and thermal coupling means between the heating element and the glassceramic plate as well as the heat spreader means across the plate.
2. A glass-ceramic plate as recited in claim 1 wherein the said recess means on the underside of the glassceramic plate is formed with a plurality of cavities that are also filled with the metal casting so as to increase the area of contact between the glass-ceramic plate and the metal casting.
3. A surface heating unit as recited in claim 1 wherein there is a reflector pan positioned beneath the glass-ceramic plate and having a peripheral edge near the top portion of the pan on which the said reinforcing member is seated, and fastening means joining the re flector pan to the reinforcing member, the area of the glass-ceramic plate in contact with the metal casting being provided with a textured surface having a plurality of cavities for increasing the area of contact between these two parts and hence the thermal coupling action.
Claims (3)
1. A surface heating unit comprising a glass-ceramic plate having recess means formed on the underside thereof, the recess means substantially covering a large area of the plate and being substantially filled with a metal casting of high thermal conductivity such as aluminum or copper that is formed in place, a metal sheathed electrical resistance heating element with a reinforcing member of open framework fastened across the underside of the heating element, the heating element and reinforcing member being partially embedded in the said metal casting, whereby the metal casting serves as both a mechanical and thermal coupling means between the heating element and the glass-ceraMic plate as well as the heat spreader means across the plate.
2. A glass-ceramic plate as recited in claim 1 wherein the said recess means on the underside of the glass-ceramic plate is formed with a plurality of cavities that are also filled with the metal casting so as to increase the area of contact between the glass-ceramic plate and the metal casting.
3. A surface heating unit as recited in claim 1 wherein there is a reflector pan positioned beneath the glass-ceramic plate and having a peripheral edge near the top portion of the pan on which the said reinforcing member is seated, and fastening means joining the reflector pan to the reinforcing member, the area of the glass-ceramic plate in contact with the metal casting being provided with a textured surface having a plurality of cavities for increasing the area of contact between these two parts and hence the thermal coupling action.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US484421A US3885128A (en) | 1974-07-01 | 1974-07-01 | Glass-ceramic plate heating unit cast-in heat spreader |
| CA227,645A CA1046122A (en) | 1974-07-01 | 1975-05-23 | Glass-ceramic plate heating unit with cast-in heat spreader plate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US484421A US3885128A (en) | 1974-07-01 | 1974-07-01 | Glass-ceramic plate heating unit cast-in heat spreader |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3885128A true US3885128A (en) | 1975-05-20 |
Family
ID=23924110
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US484421A Expired - Lifetime US3885128A (en) | 1974-07-01 | 1974-07-01 | Glass-ceramic plate heating unit cast-in heat spreader |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US3885128A (en) |
| CA (1) | CA1046122A (en) |
Cited By (26)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4045653A (en) * | 1976-06-28 | 1977-08-30 | National Presto Industries, Inc. | Electric cooker with press-staked heating element and method of making the same |
| FR2376370A1 (en) * | 1976-12-30 | 1978-07-28 | Bosch Siemens Hausgeraete | BAKING PLATE, IN PARTICULAR GLASS CERAMIC PLATE |
| FR2410790A1 (en) * | 1977-12-02 | 1979-06-29 | Bosch Siemens Hausgeraete | BAKING PLATE, PREFERREDLY VITROCERAMIC HOB |
| EP0037037A1 (en) * | 1980-03-27 | 1981-10-07 | Helmut Klotz | Base for cooking pots |
| US4394564A (en) * | 1981-12-21 | 1983-07-19 | General Electric Company | Solid plate heating unit |
| EP0093273A3 (en) * | 1982-05-03 | 1984-03-14 | Elpag Ag Chur | Radiation unit for a range or the like |
| US4481407A (en) * | 1980-05-12 | 1984-11-06 | Stokes (Australasia) Limited | Electric hotplate |
| US4634841A (en) * | 1985-06-18 | 1987-01-06 | Laughrey James C | Cover for cooking stove heating element |
| US4740664A (en) * | 1987-01-05 | 1988-04-26 | General Electric Company | Temperature limiting arrangement for a glass-ceramic cooktop appliance |
| US4788414A (en) * | 1986-04-24 | 1988-11-29 | E.G.O. Elektro-Gerate Blanc U. Fischer | Radiant heating unit for cookers or the like |
| US4843218A (en) * | 1985-12-20 | 1989-06-27 | Bosch-Siemens Hausgerate Gmbh | Heating element for thermal heating devices, especially cooking stations |
| US4962297A (en) * | 1988-03-30 | 1990-10-09 | Aktiebolaget Electrolux | Temperature controlled hot plate |
| US5220155A (en) * | 1992-03-12 | 1993-06-15 | Emerson Electric Co. | Heating and sensing apparatus for range top |
| US5221829A (en) * | 1990-10-15 | 1993-06-22 | Shimon Yahav | Domestic cooking apparatus |
| GB2277145A (en) * | 1993-04-13 | 1994-10-19 | Redring Electric Ltd | A hob |
| US5410128A (en) * | 1994-01-03 | 1995-04-25 | White Consolidated Ind Inc | Hold down spring clip for electric range coil type heating elements |
| US5422459A (en) * | 1992-03-12 | 1995-06-06 | Zibo Electrothermal Appliances Factory | Hot plate with shaped double walled electric heating element to promote heat transfer |
| US5467695A (en) * | 1993-09-29 | 1995-11-21 | Blanco Gmbh & Co. Kg | Device for preparing foods |
| WO1996025630A1 (en) * | 1995-02-15 | 1996-08-22 | Shute Alan B | Counter-top cooking unit using natural stone |
| GB2323922A (en) * | 1997-04-02 | 1998-10-07 | Redring Electric Ltd | A heating unit for a hob |
| US5994674A (en) * | 1993-04-13 | 1999-11-30 | Gda Applied Energy Limited | Hob |
| US6111229A (en) * | 1997-10-23 | 2000-08-29 | Schott Glas | Cooking appliance such as a stove with an arrangement of a ceramic heating element as a cooking zone in a cutout of a cooking surface |
| US6462316B1 (en) | 2000-10-10 | 2002-10-08 | General Electric Company | Cooktop control and monitoring system including detecting properties of a utensil and its contents |
| US6510888B1 (en) * | 2001-08-01 | 2003-01-28 | Applied Materials, Inc. | Substrate support and method of fabricating the same |
| US20040084439A1 (en) * | 2002-10-23 | 2004-05-06 | Henri Galliou | Sheathed heating element with positive temperature coefficient |
| US20180263413A1 (en) * | 2017-03-14 | 2018-09-20 | Illinois Tool Works Inc. | Cooking appliance and related heater assembly |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1924409A (en) * | 1929-08-28 | 1933-08-29 | Manson George James | Heated die for drying fibrous articles |
| US2152126A (en) * | 1936-10-02 | 1939-03-28 | John Wentworth | Heating device |
| US3519798A (en) * | 1967-04-07 | 1970-07-07 | Siemens Ag | Device for thermal processing of semiconductor wafers |
| US3569672A (en) * | 1969-05-01 | 1971-03-09 | Gen Electric | Low thermal mass, plate surface heating unit |
| US3622754A (en) * | 1970-07-24 | 1971-11-23 | Gen Electric | Glass plate surface heating unit with even temperature distribution |
| US3632983A (en) * | 1970-10-13 | 1972-01-04 | Gen Electric | Smooth surfaced, heated cooktop |
| US3805023A (en) * | 1972-03-31 | 1974-04-16 | Horizons Inc | Electrical heating device having metal depositions: in a porous anodized metal layer |
| US3816704A (en) * | 1972-03-20 | 1974-06-11 | Gen Electric | Surface heating apparatus |
-
1974
- 1974-07-01 US US484421A patent/US3885128A/en not_active Expired - Lifetime
-
1975
- 1975-05-23 CA CA227,645A patent/CA1046122A/en not_active Expired
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1924409A (en) * | 1929-08-28 | 1933-08-29 | Manson George James | Heated die for drying fibrous articles |
| US2152126A (en) * | 1936-10-02 | 1939-03-28 | John Wentworth | Heating device |
| US3519798A (en) * | 1967-04-07 | 1970-07-07 | Siemens Ag | Device for thermal processing of semiconductor wafers |
| US3569672A (en) * | 1969-05-01 | 1971-03-09 | Gen Electric | Low thermal mass, plate surface heating unit |
| US3622754A (en) * | 1970-07-24 | 1971-11-23 | Gen Electric | Glass plate surface heating unit with even temperature distribution |
| US3632983A (en) * | 1970-10-13 | 1972-01-04 | Gen Electric | Smooth surfaced, heated cooktop |
| US3816704A (en) * | 1972-03-20 | 1974-06-11 | Gen Electric | Surface heating apparatus |
| US3805023A (en) * | 1972-03-31 | 1974-04-16 | Horizons Inc | Electrical heating device having metal depositions: in a porous anodized metal layer |
Cited By (37)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4045653A (en) * | 1976-06-28 | 1977-08-30 | National Presto Industries, Inc. | Electric cooker with press-staked heating element and method of making the same |
| FR2376370A1 (en) * | 1976-12-30 | 1978-07-28 | Bosch Siemens Hausgeraete | BAKING PLATE, IN PARTICULAR GLASS CERAMIC PLATE |
| FR2410790A1 (en) * | 1977-12-02 | 1979-06-29 | Bosch Siemens Hausgeraete | BAKING PLATE, PREFERREDLY VITROCERAMIC HOB |
| EP0037037A1 (en) * | 1980-03-27 | 1981-10-07 | Helmut Klotz | Base for cooking pots |
| US4481407A (en) * | 1980-05-12 | 1984-11-06 | Stokes (Australasia) Limited | Electric hotplate |
| US4394564A (en) * | 1981-12-21 | 1983-07-19 | General Electric Company | Solid plate heating unit |
| EP0093273A3 (en) * | 1982-05-03 | 1984-03-14 | Elpag Ag Chur | Radiation unit for a range or the like |
| US4634841A (en) * | 1985-06-18 | 1987-01-06 | Laughrey James C | Cover for cooking stove heating element |
| US4843218A (en) * | 1985-12-20 | 1989-06-27 | Bosch-Siemens Hausgerate Gmbh | Heating element for thermal heating devices, especially cooking stations |
| US4788414A (en) * | 1986-04-24 | 1988-11-29 | E.G.O. Elektro-Gerate Blanc U. Fischer | Radiant heating unit for cookers or the like |
| US4740664A (en) * | 1987-01-05 | 1988-04-26 | General Electric Company | Temperature limiting arrangement for a glass-ceramic cooktop appliance |
| DE3744372C2 (en) * | 1987-01-05 | 1999-08-12 | Gen Electric | Power control method for protecting glass ceramic cooking surfaces |
| US4962297A (en) * | 1988-03-30 | 1990-10-09 | Aktiebolaget Electrolux | Temperature controlled hot plate |
| US5221829A (en) * | 1990-10-15 | 1993-06-22 | Shimon Yahav | Domestic cooking apparatus |
| US5374807A (en) * | 1990-10-15 | 1994-12-20 | Yahav; Shimon | Domestic cooking apparatus |
| US5508495A (en) * | 1990-10-15 | 1996-04-16 | Yahav; Shimon | Domestic cooking apparatus |
| US5220155A (en) * | 1992-03-12 | 1993-06-15 | Emerson Electric Co. | Heating and sensing apparatus for range top |
| US5422459A (en) * | 1992-03-12 | 1995-06-06 | Zibo Electrothermal Appliances Factory | Hot plate with shaped double walled electric heating element to promote heat transfer |
| GB2277145B (en) * | 1993-04-13 | 1997-08-27 | Redring Electric Ltd | A hob |
| GB2277145A (en) * | 1993-04-13 | 1994-10-19 | Redring Electric Ltd | A hob |
| US5994674A (en) * | 1993-04-13 | 1999-11-30 | Gda Applied Energy Limited | Hob |
| US5467695A (en) * | 1993-09-29 | 1995-11-21 | Blanco Gmbh & Co. Kg | Device for preparing foods |
| US5410128A (en) * | 1994-01-03 | 1995-04-25 | White Consolidated Ind Inc | Hold down spring clip for electric range coil type heating elements |
| WO1996025630A1 (en) * | 1995-02-15 | 1996-08-22 | Shute Alan B | Counter-top cooking unit using natural stone |
| US5640947A (en) * | 1995-02-15 | 1997-06-24 | Shute; Alan B. | Counter-top cooking unit using natural stone |
| GB2323922B (en) * | 1997-04-02 | 2001-08-29 | Redring Electric Ltd | A heating unit for a hob |
| GB2323922A (en) * | 1997-04-02 | 1998-10-07 | Redring Electric Ltd | A heating unit for a hob |
| EP0911586A3 (en) * | 1997-10-23 | 2002-02-06 | Schott Glas | Mounting of a ceramic cooking heater in an opening of a cooking hob |
| US6111229A (en) * | 1997-10-23 | 2000-08-29 | Schott Glas | Cooking appliance such as a stove with an arrangement of a ceramic heating element as a cooking zone in a cutout of a cooking surface |
| US6462316B1 (en) | 2000-10-10 | 2002-10-08 | General Electric Company | Cooktop control and monitoring system including detecting properties of a utensil and its contents |
| US6510888B1 (en) * | 2001-08-01 | 2003-01-28 | Applied Materials, Inc. | Substrate support and method of fabricating the same |
| WO2003012835A3 (en) * | 2001-08-01 | 2003-08-28 | Applied Materials Inc | Substrate support and method of fabricating the same |
| CN100470715C (en) * | 2001-08-01 | 2009-03-18 | 应用材料有限公司 | Substrate support and method for manufacturing the same |
| US20040084439A1 (en) * | 2002-10-23 | 2004-05-06 | Henri Galliou | Sheathed heating element with positive temperature coefficient |
| US6919542B2 (en) * | 2002-10-23 | 2005-07-19 | Seb S.A. | Sheathed heating element with positive temperature coefficient |
| US20180263413A1 (en) * | 2017-03-14 | 2018-09-20 | Illinois Tool Works Inc. | Cooking appliance and related heater assembly |
| US11154162B2 (en) * | 2017-03-14 | 2021-10-26 | Illinois Tool Works Inc. | Cooking appliance and related heater assembly |
Also Published As
| Publication number | Publication date |
|---|---|
| CA1046122A (en) | 1979-01-09 |
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