CA1046122A - Glass-ceramic plate heating unit with cast-in heat spreader plate - Google Patents
Glass-ceramic plate heating unit with cast-in heat spreader plateInfo
- Publication number
- CA1046122A CA1046122A CA227,645A CA227645A CA1046122A CA 1046122 A CA1046122 A CA 1046122A CA 227645 A CA227645 A CA 227645A CA 1046122 A CA1046122 A CA 1046122A
- Authority
- CA
- Canada
- Prior art keywords
- glass
- plate
- ceramic plate
- heating element
- underside
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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
Landscapes
- 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
ABSTRACT OF THE DISCLOSURE
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 con-ductivity 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 con-tact between the high conductivity layer and the glass-ceramic plate.
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 con-ductivity 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 con-tact between the high conductivity layer and the glass-ceramic plate.
Description
~046~2 9D-RG-10232 (1) Field of the Invention:
The invention relates to glass-ceramic plate surface heating unitq or cooktops with a metal sheathed heating element cast into a heat spreading layer on the underside o~ the plate.
The invention relates to glass-ceramic plate surface heating unitq or cooktops with a metal sheathed heating element cast into a heat spreading layer on the underside o~ the plate.
(2) Description of the Prior Art:
In order to improve the cleanàbility of cooktops of domestic ranges as well as built-in countertop cooktQps~
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 milk-white, opaque, glass_ ceramic or crystalline glass material sold under such trade-marks as "PYROCERAM", "CER-VIT", and "HERCUVIT". This glass-ceramic material has a low thermal expan8ion 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 U.S Patent No. 3,632,983 issued January ~
4, 1972 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 therma~ly than standard porcelain ena-melled steel cooktops having metal sheathed electrical resi-stance 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 glass-ceramic plate as well as in the sheathed heating element and - 1 - ~
1~46~Z2 9D-RG-10232 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 i8 also a poor thermal cou_ pLing between the heater and the glass-ceramic plate, In order to transfer the heat from an open coil heater to the glass-ceramic 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, overheating 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 con-ductivity through the glass-ceramic material, Such material is used widely in other arts as thermal and electrical in-sulating material, rather than as a thermal conductor in the present invention, Heat does not readily diffuse lat_ erally through the glass-ceramic plate, and during a cooking operating 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 is glass-ceramic plate heating units is taught in U,S, Patent No. 3,622,754 issued November 239 1971 of Bohdan Hurko, which is also assigned to the present assignee, This Hurko patent employs a metal sheathed heating element that is attached to the underside of a thin composite plate having a core of high thermal conductivity such as copper, silver or aluminum, m e 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 sur~ace heating unit or cooktop with a cast-in heat spreader plate which also serves a~3 a mechanical and thermal coupling means for the heating element A further object of the 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 glass-ceramic plate.
The present invention, in accordance with one form thereof, relates to a solid plate surface heating unit com-prising 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.
This invention will be better understood from the following description taken in conjunction with the acc-ompanying drawings and its scope will be pointed out in the appended claims FIGURE 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.
1~6122 FIGURE 2 is a bottom plane view of the glas~_ceramic plate of FI~URE 1 showing a pattern of a plurality of cavities formed on the underside of the glass-ceramic plate so as to increase the sur~ace area of contact between the heat spreader casting and the glass-ceramic plate.
Turning now to a conRideration o~ the drawings and in partieular to FIGURE 1, there is shown a cross_sectional, elevation view of a solid plate surface heating unit 10 having a thin glass-eeramic plate 12 whieh is a molded part of generally eireular configuration having an inverted pan-shape by virtue of a recess 14 ereated on the underside of the glass-eeramie plate due to the presenee of a down_ turn peripheral wall 15. In other words, this glass-eeramie plate is not a simple plate of uniform thiekness throughout, as in most, if not all, glass-ceramic cooktops sold widely on the market today. While this invention is shown ineorporated in a single solid plate surfaee heating unit, it should be understood that it is equally applieable in a cooktop having a plurality of heated areas, where each heated area would have its own heat spreader layer 16. -~
This glass-eeramie material is eleetrieally insulating and thermally transmissive as well as being highly wear and `-thermal shock resistant, and resistant to the physieal and chemieal attaeks of foods and liquids which may eome in con-taet with the plate at relatively high temperatures. While -the term glass_eeramie material or erystalline glass material is used throughout, it should be understood that this invention eneompasses other materials with similar eharaeteristies, sueh as quartz, high-siliea glass, high-temperature glass and different eeramie materials.
It would be extremely diffieult to maintain an even temperature distribution aeross this glass-eeramic plate 12 - -1~)461ZZ 9D--RG-10232 if it were heated dixectly by an open coil resistance heating element or a metal sheathed resi~tance heating element of looped configuration. Heat diffuses very slowly laterally through the glass_ceramic material~ and hence, hot sports w~uld 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 wraped bottom of a cooking utensil. This ~;
type of glass cannot exceed an operational temperature of about 1300F at any point, hence, the total heat output of a glass-ceramic 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 of 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_asse~ibly of a metal sheathed electrical resistance heating element 18 of sprial coolfiguration is first staked or otherwise mounted on a reinforcing support 20 of open framework. mis sub-assembly is placed in contact with the molten metal 16 such that as the metal solidified 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 ~oining the heating element in an electrical circuit A reflector pan 26 of rather deep configuration is positioned beneath the heating unit 18 and reinforcing frame-work 20. The upper perimeter of the reflector pan 26 has an outwardly extending ledge 28 on which the supporting frame-, . i ~
1~461ZZ 9D_RG_102 3 2 work 20 is seated. A J-bolt 32 is hooked to the r~infor-cing frame 20 at its upper end 34, while the lower threaded end of the ~-bolt extends through an opening 36 in the bottom of the reflector pan 26 and a nut 38 i8 tightened on the bolt until the surface unit 10 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 1300 F, This can best be done by introducing a temperature-limiting means to the solid plate surface unit of the pre-sent inv~ntion such that the power to the heating element 18 is cut off if the temperature of the heat spreader cast-ing 16 rises to a predetermined temperature, This temper-ature-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 posittoned on the reinforcing framework 20 and cast in the heat spread_ `
er layer 16, m is sensor 42 i8 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 single_point, 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 tem-perature 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, As similar arrangement is utilized in the Hurko U~S.- Patent 3,622,754 issued November 23~ 1971.
.
. , This solid plate surface heating unit 10 i8 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 meanQ for holding the surface unit 10 down in place, and this function is provided by a trim ring 56 which has a transverse T-~haped cross-section with a first vertical shank section 58 which is insertable into the nar-row gap between the periphery of the heating unit 10 and the vertical side 60 created by the recessed ledge 52 The upper edge of the 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 i8 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 ~ 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 FIGURE 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 m is lower V-portion 78 has an .. . .
:
1~461ZZ 9D_RG_10232 apex 80 that is directed generally toward the edg~ of the ledge 52 of the cooktop 50 to serve as a detent member, .
such that when the surface unit 10 i8 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.
m ere is a tendency for the metal casting 16 to con-A~. tr~c~
~act slightly from the glass-ceramic plate 12 as the casting solidifies. This effect can be counterbalanced by providing a pattern of concavities 85 in the glass surface in the re-cess 14, as i8 best seen in the bottom plan-- view of FIGURE - ~-2 This increases the surface area of contact between the .
metal casting and the glass_ceramic plate to improve the thermal coupling between these two parts. Other patterns of concavitie~ 85 may be sub~tituted such as a corrugated surface, a pebbled em~ossed or textured surface.
Modifications of this invention will occur to those s~illed 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 this invention as claimed : . , . . ~ .
In order to improve the cleanàbility of cooktops of domestic ranges as well as built-in countertop cooktQps~
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 milk-white, opaque, glass_ ceramic or crystalline glass material sold under such trade-marks as "PYROCERAM", "CER-VIT", and "HERCUVIT". This glass-ceramic material has a low thermal expan8ion 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 U.S Patent No. 3,632,983 issued January ~
4, 1972 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 therma~ly than standard porcelain ena-melled steel cooktops having metal sheathed electrical resi-stance 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 glass-ceramic plate as well as in the sheathed heating element and - 1 - ~
1~46~Z2 9D-RG-10232 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 i8 also a poor thermal cou_ pLing between the heater and the glass-ceramic plate, In order to transfer the heat from an open coil heater to the glass-ceramic 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, overheating 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 con-ductivity through the glass-ceramic material, Such material is used widely in other arts as thermal and electrical in-sulating material, rather than as a thermal conductor in the present invention, Heat does not readily diffuse lat_ erally through the glass-ceramic plate, and during a cooking operating 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 is glass-ceramic plate heating units is taught in U,S, Patent No. 3,622,754 issued November 239 1971 of Bohdan Hurko, which is also assigned to the present assignee, This Hurko patent employs a metal sheathed heating element that is attached to the underside of a thin composite plate having a core of high thermal conductivity such as copper, silver or aluminum, m e 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 sur~ace heating unit or cooktop with a cast-in heat spreader plate which also serves a~3 a mechanical and thermal coupling means for the heating element A further object of the 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 glass-ceramic plate.
The present invention, in accordance with one form thereof, relates to a solid plate surface heating unit com-prising 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.
This invention will be better understood from the following description taken in conjunction with the acc-ompanying drawings and its scope will be pointed out in the appended claims FIGURE 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.
1~6122 FIGURE 2 is a bottom plane view of the glas~_ceramic plate of FI~URE 1 showing a pattern of a plurality of cavities formed on the underside of the glass-ceramic plate so as to increase the sur~ace area of contact between the heat spreader casting and the glass-ceramic plate.
Turning now to a conRideration o~ the drawings and in partieular to FIGURE 1, there is shown a cross_sectional, elevation view of a solid plate surface heating unit 10 having a thin glass-eeramic plate 12 whieh is a molded part of generally eireular configuration having an inverted pan-shape by virtue of a recess 14 ereated on the underside of the glass-eeramie plate due to the presenee of a down_ turn peripheral wall 15. In other words, this glass-eeramie plate is not a simple plate of uniform thiekness throughout, as in most, if not all, glass-ceramic cooktops sold widely on the market today. While this invention is shown ineorporated in a single solid plate surfaee heating unit, it should be understood that it is equally applieable in a cooktop having a plurality of heated areas, where each heated area would have its own heat spreader layer 16. -~
This glass-eeramie material is eleetrieally insulating and thermally transmissive as well as being highly wear and `-thermal shock resistant, and resistant to the physieal and chemieal attaeks of foods and liquids which may eome in con-taet with the plate at relatively high temperatures. While -the term glass_eeramie material or erystalline glass material is used throughout, it should be understood that this invention eneompasses other materials with similar eharaeteristies, sueh as quartz, high-siliea glass, high-temperature glass and different eeramie materials.
It would be extremely diffieult to maintain an even temperature distribution aeross this glass-eeramic plate 12 - -1~)461ZZ 9D--RG-10232 if it were heated dixectly by an open coil resistance heating element or a metal sheathed resi~tance heating element of looped configuration. Heat diffuses very slowly laterally through the glass_ceramic material~ and hence, hot sports w~uld 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 wraped bottom of a cooking utensil. This ~;
type of glass cannot exceed an operational temperature of about 1300F at any point, hence, the total heat output of a glass-ceramic 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 of 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_asse~ibly of a metal sheathed electrical resistance heating element 18 of sprial coolfiguration is first staked or otherwise mounted on a reinforcing support 20 of open framework. mis sub-assembly is placed in contact with the molten metal 16 such that as the metal solidified 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 ~oining the heating element in an electrical circuit A reflector pan 26 of rather deep configuration is positioned beneath the heating unit 18 and reinforcing frame-work 20. The upper perimeter of the reflector pan 26 has an outwardly extending ledge 28 on which the supporting frame-, . i ~
1~461ZZ 9D_RG_102 3 2 work 20 is seated. A J-bolt 32 is hooked to the r~infor-cing frame 20 at its upper end 34, while the lower threaded end of the ~-bolt extends through an opening 36 in the bottom of the reflector pan 26 and a nut 38 i8 tightened on the bolt until the surface unit 10 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 1300 F, This can best be done by introducing a temperature-limiting means to the solid plate surface unit of the pre-sent inv~ntion such that the power to the heating element 18 is cut off if the temperature of the heat spreader cast-ing 16 rises to a predetermined temperature, This temper-ature-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 posittoned on the reinforcing framework 20 and cast in the heat spread_ `
er layer 16, m is sensor 42 i8 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 single_point, 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 tem-perature 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, As similar arrangement is utilized in the Hurko U~S.- Patent 3,622,754 issued November 23~ 1971.
.
. , This solid plate surface heating unit 10 i8 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 meanQ for holding the surface unit 10 down in place, and this function is provided by a trim ring 56 which has a transverse T-~haped cross-section with a first vertical shank section 58 which is insertable into the nar-row gap between the periphery of the heating unit 10 and the vertical side 60 created by the recessed ledge 52 The upper edge of the 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 i8 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 ~ 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 FIGURE 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 m is lower V-portion 78 has an .. . .
:
1~461ZZ 9D_RG_10232 apex 80 that is directed generally toward the edg~ of the ledge 52 of the cooktop 50 to serve as a detent member, .
such that when the surface unit 10 i8 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.
m ere is a tendency for the metal casting 16 to con-A~. tr~c~
~act slightly from the glass-ceramic plate 12 as the casting solidifies. This effect can be counterbalanced by providing a pattern of concavities 85 in the glass surface in the re-cess 14, as i8 best seen in the bottom plan-- view of FIGURE - ~-2 This increases the surface area of contact between the .
metal casting and the glass_ceramic plate to improve the thermal coupling between these two parts. Other patterns of concavitie~ 85 may be sub~tituted such as a corrugated surface, a pebbled em~ossed or textured surface.
Modifications of this invention will occur to those s~illed 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 this invention as claimed : . , . . ~ .
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 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.
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 |
|---|---|
| CA1046122A true CA1046122A (en) | 1979-01-09 |
Family
ID=23924110
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA227,645A Expired CA1046122A (en) | 1974-07-01 | 1975-05-23 | Glass-ceramic plate heating unit with cast-in heat spreader plate |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US3885128A (en) |
| CA (1) | CA1046122A (en) |
Families Citing this family (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 |
| DE7641069U1 (en) * | 1976-12-30 | 1978-06-22 | Bosch-Siemens Hausgeraete Gmbh, 7000 Stuttgart | COOKING PLATE, PREFERABLY CERAMIC GLASS COOKING PLATE |
| DE7736873U1 (en) * | 1977-12-02 | 1979-05-10 | Bosch-Siemens Hausgeraete Gmbh, 7000 Stuttgart | COOKING PLATE, PREFERABLY CERAMIC GLASS 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 |
| DE3216508A1 (en) * | 1982-05-03 | 1983-11-03 | Elpag AG Chur, 7001 Chur | RADIATION UNIT FOR A STOVE OR THE LIKE |
| US4634841A (en) * | 1985-06-18 | 1987-01-06 | Laughrey James C | Cover for cooking stove heating element |
| DE3545442A1 (en) * | 1985-12-20 | 1987-06-25 | Bosch Siemens Hausgeraete | HEATING ELEMENT FOR THERMAL HOME APPLIANCES, ESPECIALLY FOR COOKING POINTS |
| DE3613901A1 (en) * | 1986-04-24 | 1987-10-29 | Ego Elektro Blanc & Fischer | BEAM RADIATOR FOR COOKING APPLIANCES OR THE LIKE |
| US4740664A (en) * | 1987-01-05 | 1988-04-26 | General Electric Company | Temperature limiting arrangement for a glass-ceramic cooktop appliance |
| SE460450B (en) * | 1988-03-30 | 1989-10-09 | Electrolux Ab | TEMPERATURE REGULATED COOKING TABLE |
| US5221829A (en) * | 1990-10-15 | 1993-06-22 | Shimon Yahav | Domestic cooking apparatus |
| US5220155A (en) * | 1992-03-12 | 1993-06-15 | Emerson Electric Co. | Heating and sensing apparatus for range top |
| CN1076326A (en) * | 1992-03-12 | 1993-09-15 | 淄博电热电器厂 | Combined type electric heating plate moulding process and electric heating plate |
| GB2277145B (en) * | 1993-04-13 | 1997-08-27 | Redring Electric Ltd | A hob |
| US5994674A (en) * | 1993-04-13 | 1999-11-30 | Gda Applied Energy Limited | Hob |
| DE4333158A1 (en) * | 1993-09-29 | 1995-03-30 | Blanco Gmbh & Co Kg | Appliance for preparing food |
| US5410128A (en) * | 1994-01-03 | 1995-04-25 | White Consolidated Ind Inc | Hold down spring clip for electric range coil type heating elements |
| US5640947A (en) * | 1995-02-15 | 1997-06-24 | Shute; Alan B. | Counter-top cooking unit using natural stone |
| GB2351553B (en) * | 1997-04-02 | 2001-03-14 | Gda Applied Energy Ltd | A heating unit for a hob |
| DE19746844C1 (en) * | 1997-10-23 | 1998-12-03 | Schott Glas | Ceramic heating element for electric cooking hob |
| 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 |
| FR2846509B1 (en) * | 2002-10-23 | 2006-03-17 | Seb Sa | PTC EFFECT ARMORED HEATING ELEMENT |
| US11154162B2 (en) * | 2017-03-14 | 2021-10-26 | Illinois Tool Works Inc. | Cooking appliance and related heater assembly |
Family Cites Families (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 |
| DE1619999A1 (en) * | 1967-04-07 | 1970-03-26 | Siemens Ag | Device for the thermal treatment of disc-shaped bodies for semiconductor purposes |
| 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 |
-
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
Also Published As
| Publication number | Publication date |
|---|---|
| US3885128A (en) | 1975-05-20 |
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