US20200253409A1 - Cooking device having a cooking vessel and a ceramic heater - Google Patents
Cooking device having a cooking vessel and a ceramic heater Download PDFInfo
- Publication number
- US20200253409A1 US20200253409A1 US16/782,318 US202016782318A US2020253409A1 US 20200253409 A1 US20200253409 A1 US 20200253409A1 US 202016782318 A US202016782318 A US 202016782318A US 2020253409 A1 US2020253409 A1 US 2020253409A1
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- Prior art keywords
- heater
- ceramic substrate
- cooking
- resistive trace
- cooking device
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Links
- 238000010411 cooking Methods 0.000 title claims abstract description 145
- 239000000919 ceramic Substances 0.000 title claims abstract description 113
- 239000000758 substrate Substances 0.000 claims abstract description 103
- 238000010438 heat treatment Methods 0.000 claims abstract description 53
- 239000000463 material Substances 0.000 claims abstract description 18
- 235000013305 food Nutrition 0.000 claims abstract description 17
- 239000011521 glass Substances 0.000 claims description 19
- 238000012546 transfer Methods 0.000 claims description 9
- 238000004891 communication Methods 0.000 claims description 4
- 239000010410 layer Substances 0.000 description 20
- 241000209094 Oryza Species 0.000 description 8
- 235000007164 Oryza sativa Nutrition 0.000 description 8
- 230000006698 induction Effects 0.000 description 8
- 235000009566 rice Nutrition 0.000 description 8
- 229910052782 aluminium Inorganic materials 0.000 description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 7
- 239000004020 conductor Substances 0.000 description 7
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 238000009833 condensation Methods 0.000 description 5
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- 238000001704 evaporation Methods 0.000 description 4
- 230000008020 evaporation Effects 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 206010014357 Electric shock Diseases 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 229910001120 nichrome Inorganic materials 0.000 description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 2
- SWELZOZIOHGSPA-UHFFFAOYSA-N palladium silver Chemical compound [Pd].[Ag] SWELZOZIOHGSPA-UHFFFAOYSA-N 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 239000002356 single layer Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- IHWJXGQYRBHUIF-UHFFFAOYSA-N [Ag].[Pt] Chemical compound [Ag].[Pt] IHWJXGQYRBHUIF-UHFFFAOYSA-N 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 239000012772 electrical insulation material Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 239000004519 grease Substances 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 239000011224 oxide ceramic Substances 0.000 description 1
- 229910052574 oxide ceramic Inorganic materials 0.000 description 1
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Images
Classifications
-
- A—HUMAN NECESSITIES
- A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
- A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
- A47J27/00—Cooking-vessels
- A47J27/004—Cooking-vessels with integral electrical heating means
-
- A—HUMAN NECESSITIES
- A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
- A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
- A47J27/00—Cooking-vessels
- A47J27/02—Cooking-vessels with enlarged heating surfaces
-
- A—HUMAN NECESSITIES
- A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
- A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
- A47J36/00—Parts, details or accessories of cooking-vessels
- A47J36/02—Selection of specific materials, e.g. heavy bottoms with copper inlay or with insulating inlay
- A47J36/04—Selection of specific materials, e.g. heavy bottoms with copper inlay or with insulating inlay the materials being non-metallic
-
- 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
- F24C15/005—Coatings for ovens
-
- 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
- F24C15/32—Arrangements of ducts for hot gases, e.g. in or around baking ovens
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
- F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
- F28D15/0233—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes the conduits having a particular shape, e.g. non-circular cross-section, annular
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
- F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
- F28D15/0275—Arrangements for coupling heat-pipes together or with other structures, e.g. with base blocks; Heat pipe cores
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
- F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
- F28D15/04—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure
- F28D15/046—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure characterised by the material or the construction of the capillary structure
-
- 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
- H05B1/00—Details of electric heating devices
- H05B1/02—Automatic switching arrangements specially adapted to apparatus ; Control of heating devices
- H05B1/0227—Applications
- H05B1/0252—Domestic applications
- H05B1/0258—For cooking
- H05B1/0261—For cooking of food
-
- 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
- H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
- H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
- H05B3/14—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
- H05B3/141—Conductive ceramics, e.g. metal oxides, metal carbides, barium titanate, ferrites, zirconia, vitrous compounds
-
- 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
- H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater
- H05B3/22—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible
- H05B3/26—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor mounted on insulating base
- H05B3/265—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor mounted on insulating base the insulating base being an inorganic material, e.g. ceramic
-
- A—HUMAN NECESSITIES
- A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
- A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
- A47J2202/00—Devices having temperature indicating means
-
- 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
- F24C7/00—Stoves or ranges heated by electric energy
- F24C7/06—Arrangement or mounting of electric heating elements
- F24C7/067—Arrangement or mounting of electric heating elements on ranges
-
- 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
- H05B1/00—Details of electric heating devices
- H05B1/02—Automatic switching arrangements specially adapted to apparatus ; Control of heating devices
- H05B1/0202—Switches
-
- 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
- H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
- H05B2203/013—Heaters using resistive films or coatings
-
- 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
- H05B2213/00—Aspects relating both to resistive heating and to induction heating, covered by H05B3/00 and H05B6/00
- H05B2213/07—Heating plates with temperature control means
-
- 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
- H05B3/76—Plates with spirally-wound heating tubes
Definitions
- the present disclosure relates generally to cooking devices and more particularly to a cooking device having a cooking vessel and a ceramic heater.
- nichrome wire potted with ceramic cement inside a stainless steel sheath embedded inside a cast aluminum body. These heaters generate heat by passing electrical current through the nichrome wire. These types of heaters often suffer from long warmup and cooldown times due to the high thermal mass provided by the electrical insulation materials and the relatively large metal components. Furthermore, cooking vessels used with wire coil heaters typically have relatively low thermal mass resulting in poor distribution of heat within the cooking vessel.
- Some high-end rice cookers utilize induction heaters to directly warm the cooking vessel instead of relying on convection or thermal conduction.
- Induction rice cookers use induction heating where current is passed through a metal coil to create a magnetic field. The cooking vessel is positioned within the magnetic field to induce electrical current in the cooking vessel which, in turn, generates heat. With induction heating, the heating temperature may be controlled by adjusting the strength of the magnetic field allowing for shorter warmup and cooldown times to be achieved.
- induction heaters are generally expensive due to the cost of the electrical materials and components, and the control systems for induction heaters are relatively complex and generally expensive as a result.
- a cooking device includes a base having a top surface positioned to contact a cooking vessel configured to hold food during cooking.
- the base includes a heater having a ceramic substrate and an electrically resistive trace on an exterior surface of the ceramic substrate.
- the heater is positioned to supply heat generated by applying an electric current to the electrically resistive trace to the top surface of the base for heating the cooking vessel to heat food in the cooking vessel.
- the electrically resistive trace includes an electrical resistor material thick film printed on the exterior surface of the ceramic substrate.
- the electrically resistive trace is positioned on a top surface of the ceramic substrate that faces upward toward the top surface of the base.
- Embodiments include those wherein the heater includes a thermistor that is positioned on the ceramic substrate and in electrical communication with control circuitry of the heater for providing feedback regarding a temperature of the heater to the control circuitry of the heater.
- the thermistor is positioned on a bottom surface of the ceramic substrate that faces away from the top surface of the base.
- Embodiments include those wherein the base includes a heating plate that forms the top surface of the base.
- the heating plate is positioned in contact with the heater to transfer heat from the heater to the top surface of the base for heating the cooking vessel to heat food in the cooking vessel.
- the heating plate includes a domed top surface for contacting a concave bottom surface of the cooking vessel.
- Embodiments include those wherein the ceramic substrate has a polygonal shape. In some embodiments, the ceramic substrate has an octagonal shape.
- Embodiments include those wherein the electrically resistive trace extends in a serpentine pattern across the exterior surface of the ceramic substrate.
- the serpentine pattern of the electrically resistive trace has a generally circular outer perimeter.
- a cooking device includes a housing having a receptacle and a base positioned along a bottom of the receptacle.
- a cooking vessel is removably positionable within the receptacle for containing food to be cooked.
- the cooking vessel contacts the base when the cooking vessel is positioned within the receptacle.
- the base includes a heater having a ceramic substrate and an electrical resistor material thick film printed on a surface of the ceramic substrate. The heater is positioned to supply heat generated by applying an electric current to the electrical resistor material to the cooking vessel when the cooking vessel is positioned within the receptacle.
- a heater for use with a cooking device includes a ceramic substrate and an electrically resistive trace thick film printed on an exterior face of the ceramic substrate.
- the electrically resistive trace extends in a serpentine pattern across the exterior face of the ceramic substrate from a first end of the electrically resistive trace to a second end of the electrically resistive trace.
- the serpentine pattern of the electrically resistive trace has a generally circular outer perimeter.
- the heater also includes a first electrically conductive trace electrically connected to the first end of the electrically resistive trace and a second electrically conductive trace electrically connected to the second end of the electrically resistive trace.
- the first and second electrically conductive traces form respective first and second terminals providing respective first and second electrical connections for completing a circuit formed by the first and second electrically conductive traces and the electrically resistive trace.
- Some embodiments include one or more glass layers on the exterior face of the ceramic substrate that cover the electrically resistive trace electrically insulating the electrically resistive trace.
- Some embodiments include a thermistor positioned on a second exterior face of the ceramic substrate that is opposite the exterior face of the ceramic substrate on which the electrically resistive trace is positioned for providing feedback regarding a temperature of the heater to control circuitry of the heater.
- Embodiments include those wherein the ceramic substrate has a polygonal shape. In some embodiments, the ceramic substrate has an octagonal shape.
- FIG. 1 is a perspective view of a cooking device according to one example embodiment.
- FIG. 2 is a schematic diagram of the cooking device according to one example embodiment.
- FIG. 3 is an exploded perspective view of a heater assembly of the cooking device according to one example embodiment.
- FIGS. 4 and 5 are plan views of a top surface and a bottom surface, respectively, of a heater of the heater assembly shown in FIG. 3 .
- FIG. 6 is a cross-sectional view of the heater shown in FIGS. 4 and 5 taken along line 6 - 6 in FIG. 4 .
- FIG. 7 is a plan view of a top surface of a heater according to another example embodiment.
- FIG. 8 is a cross-sectional view of a cooking vessel of the cooking device employing a heat pipe according to one example embodiment.
- FIGS. 9A-9C are cross-sectional views of the cooking vessel shown in FIG. 8 taken along line 9 - 9 in FIG. 8 illustrating various example wick structures of the heat pipe.
- cooking device 100 includes a rice cooker. However, cooking device 100 may also include a pressure cooker, a steam cooker, etc.
- Cooking device 100 includes a housing 102 , a cooking vessel 120 , a lid 105 , a heater assembly 140 , and a user interface 109 .
- Housing 102 includes an upper portion having a receptacle 103 for receiving cooking vessel 120 and a lower portion within which heater assembly 140 is mounted.
- heater assembly 140 forms a receiving base of receptacle 103 such that cooking vessel 120 contacts and rests on top of heater assembly 140 when cooking vessel 120 is positioned within receptacle 103 so that heat generated by heater assembly 140 heats cooking vessel 120 .
- Cooking vessel 120 is generally a container (e.g., a bowl) having a food receptacle 121 in which food substances to be cooked, such as rice and water, are contained. That is, food receptacle 121 of cooking vessel 120 directly contacts and retains the food being cooked.
- Cooking vessel 120 may be composed of, for example, a metal having high thermal conductivity, such as stainless steel, aluminum or copper.
- Lid 105 covers the opening at a rim 122 of cooking vessel 120 .
- Lid 105 includes a handle 107 preferably composed of a material having low thermal conductivity to provide a safe surface for the user to hold when using lid 105 .
- User interface 109 is provided on a front portion of housing 102 .
- User interface 109 may include one or more buttons, dials, knobs, etc. for receiving user input and/or a display or indicator lights for providing information about the functioning and status of cooking device 100 to a user.
- Cooking device 100 also includes a power cord 112 for connecting cooking device 100 to an external power source 114 .
- food receptacle 121 of cooking vessel 120 holds water and rice to cook, and heater 140 transfers heat to cooking vessel 120 to bring the water to boil. Once the water reaches a steady boil, the temperature of cooking vessel 120 remains generally stable. Once all of the water in cooking vessel 120 is absorbed by the rice and/or evaporated, the temperature of cooking vessel 120 tends to increase, triggering a mechanism inside cooking device 100 to either turn heater assembly 140 off or to switch to a reduced temperature warming cycle intended to keep the food in cooking vessel 120 warm.
- Cooking device 100 includes heater assembly 140 including a heater 150 and a heating plate 145 .
- Heater 150 includes a substrate 152 to which at least one resistive trace 160 is secured. Heat is generated when electrical current provided by power source 114 is passed through resistive trace 160 .
- Heating plate 145 is positioned in contact with, or in very close proximity to, heater 150 in order to transfer heat from heater 150 to cooking vessel 120 .
- thermal grease is applied between heater 150 and heating plate 145 to facilitate physical contact and heat transfer between heater 150 and heating plate 145 .
- a gap filler e.g., silicon gap filler
- pad e.g., graphite gap pad
- Heating plate 145 is composed of, for to example, a metal having high thermal conductivity, such as forged aluminum.
- Cooking device 100 includes control circuitry 115 configured to control the temperature of heater 150 by selectively opening or closing a circuit supplying electrical current to resistive trace 160 . Open loop or, preferably, closed loop control may be utilized as desired.
- a temperature sensor 170 such as a thermistor, is coupled to substrate 152 for sensing the temperature of heater 150 and permitting closed loop control of heater 150 by control circuitry 115 .
- Control circuitry 115 may include a microprocessor, a microcontroller, an application-specific integrated circuit, and/or other form integrated circuit.
- User interface 109 is communicatively coupled to control circuitry 115 via a communications link 110 .
- control circuitry 115 includes a switch 117 connected between one end of resistive trace 160 and a first terminal 114 a of power source 114 .
- Switch 117 may be, for example, a mechanical switch, an electronic switch, a relay, or other switching device.
- the other end of resistive trace 160 is connected to a second terminal 114 b of power source 114 .
- the temperature of heater 150 is controlled by measuring the temperature of substrate 152 by temperature sensor 170 held in contact with substrate 152 and feeding temperature information from temperature sensor 170 to control circuitry 115 which, in turn, controls switch 117 to selectively supply power to resistive trace 160 based on the temperature information. When switch 117 is closed, current flows through resistive trace 160 to generate heat from heater 150 .
- control circuitry 115 may include power control logic and/or other circuitries for controlling the amount of power delivered to resistive trace 160 to permit adjustment of the amount of heat generated by heater 150 within a desired range of temperatures. For example, in some embodiments, when the temperature of heater 150 is low (e.g., under 100 degrees Celsius), heater 150 is supplied with 50% power and then gradually stepped up from 50% to 100% as the temperature of heater 150 increases.
- FIG. 3 shows heater assembly 140 including heating plate 145 and heater 150 according to one example embodiment.
- FIG. 4 shows a top view of heater 150
- FIG. 5 shows a bottom view of heater 150 .
- heating plate 145 is formed as a circular disk having a domed upper surface 147 (also shown in FIG. 2 with exaggerated scale for illustration purposes).
- heating plate 145 has a diameter of about 162 mm, a central portion having a thickness of about 5 mm, and a circumferential edge having a thickness of about 1 mm.
- heating plate 145 may have other shapes as long as heating plate 145 is positioned to spread heat from heater 150 across the bottom surface of cooking vessel 120 .
- the thermal conductivity and relative thinness of heating plate 145 result in a relatively low thermal mass, which reduces the amount of time required to heat and cool heating plate 145 and, in turn, cooking vessel 120 .
- Heater 150 includes substrate 152 constructed from ceramic or the like, such as aluminum oxide (e.g., commercially available 96% aluminum oxide ceramic).
- substrate 152 is referred to as ceramic substrate 152 .
- heater 150 may include one or more layers of ceramic substrate 152 .
- a thickness of ceramic substrate 152 may range from, for example, 0.5 mm to 1.5 mm, such as 1.0 mm.
- each layer may have a thickness ranging from, for example, 0.5 mm to 1.0 mm, such as 0.635 mm.
- ceramic substrate 152 is octagonal in shape having an incircle diameter d of about 147 mm.
- ceramic substrate 152 may take other suitable shapes depending on the application, such as, for example, circular, hexagonal, square, etc.
- the octagonal shape illustrated is easier to reliably manufacture on a commercial basis than, for example, a circular shape.
- Ceramic substrate 152 includes a top surface 152 a that faces heating plate 145 and a bottom surface 152 b opposite top surface 152 a .
- resistive trace 160 is positioned on top surface 152 a of ceramic substrate 152 .
- Resistive trace 160 includes a first end 160 a and a second end 160 b .
- a pair of conductive traces 162 a , 162 b are also positioned on top surface 152 a .
- Conductive traces 162 a , 162 b are connected to first and second ends 160 a , 160 b of resistive trace 160 , respectively.
- Resistive trace 160 includes a suitable electrical resistor material such as, for example, silver palladium (e.g., blended 70/30 silver palladium).
- Conductive traces 162 a , 162 b include a suitable electrical conductor material such as, for example, silver platinum.
- resistive trace 160 and conductive traces 162 a , 162 b are applied to ceramic substrate 152 by way of thick film printing.
- resistive trace 160 may include a resistor paste having a thickness of 10-13 microns when applied to ceramic substrate 152
- conductive traces 162 a , 162 b may include a conductor paste having a thickness of 9-15 microns when applied to ceramic substrate 152 .
- Resistive trace 160 forms the heating element of heater 150
- conductive traces 162 a , 162 b provide electrical connections to resistive trace 160 in order to supply an electrical current to resistive trace 160 to generate heat.
- resistive trace 160 follows a serpentine pattern extending from first end 160 a to second end 160 b along top surface 152 a of ceramic substrate 152 .
- the serpentine pattern formed by resistive trace 160 has a generally circular outer perimeter 161 .
- Conductive traces 162 a , 162 b each form a respective terminal 163 a , 163 b of heater 150 .
- Cables or wires 165 a , 165 b are connected to respective terminals 163 a , 163 b in order to electrically connect resistive trace 160 and conductive traces 162 a , 162 b to, for example, control circuitry 115 and power source 114 in order to selectively close the circuit formed by resistive trace 160 and conductive traces 162 a , 162 b to generate heat.
- Conductive trace 162 a directly contacts first end 160 a of resistive trace 160
- conductive trace 162 b directly contacts second end 160 b of resistive trace 160 .
- Conductive traces 162 a , 162 b both extend along an extension portion 155 of ceramic substrate 152 that extends from an edge 157 of ceramic substrate 152 in the example embodiment illustrated, but conductive traces 162 a , 162 b may be positioned in other suitable locations on ceramic substrate 152 as desired. Portions of first and second ends 160 a , 160 b of resistive trace 160 obscured beneath conductive traces 162 a , 162 b in FIG. 4 are shown in dotted line.
- current input to heater 150 at, for example, terminal 163 a by way of conductive trace 162 a passes through, in order, resistive trace 160 and conductive trace 162 b where it is output from heater 150 at terminal 163 b .
- Current input to heater 150 at terminal 163 b travels in reverse along the same path.
- heater 150 includes temperature sensor 170 , also referred to as thermistor 170 , positioned in close proximity to a surface of heater 150 in order to provide feedback regarding the temperature of heater 150 to control circuitry 115 .
- thermistor 170 is positioned on bottom surface 152 b of ceramic substrate 152 .
- thermistor 170 is welded directly to bottom surface 152 b of ceramic substrate 152 .
- heater 150 also includes a pair of conductive traces 172 a , 172 b that are each electrically connected to a respective terminal of thermistor 170 .
- Each conductive trace 172 a , 172 b has a distal end that forms a respective terminal 173 a , 173 b adjacent to an edge 158 of ceramic substrate 152 .
- Cables or wires 175 a , 175 b are connected to terminals 173 a , 173 b in order to electrically connect thermistor 170 to, for example, control circuitry 115 in order to provide closed loop control of heater 150 .
- thermistor 170 is positioned at a central location of bottom surface 152 b of ceramic substrate 152 .
- thermistor 170 and its corresponding conductive traces 172 a , 172 b may be positioned in other suitable locations on bottom surface 152 b of ceramic substrate 152 .
- heater 150 also includes a thermal cutoff (not shown), such as a bi-metal thermal cutoff, in contact with ceramic substrate 152 and connected in series with the heating circuit formed by resistive trace 160 and conductive traces 162 a , 162 b permitting the thermal cutoff to open the heating circuit formed by resistive trace 160 and conductive traces 162 a , 162 b upon detection by the thermal cutoff of a temperature that exceeds a predetermined amount. In this manner, the thermal cutoff provides additional safety by preventing overheating of heater 150 .
- a thermal cutoff such as a bi-metal thermal cutoff
- FIG. 6 is a cross-sectional view of heater 150 taken along line 6 - 6 in FIG. 4 .
- heater 150 includes resistive trace 160 and conductive traces 162 a , 162 b formed on ceramic substrate 152 .
- FIG. 6 depicts a single layer of ceramic substrate 152 .
- ceramic substrate 152 may include multiple layers as depicted by dashed line 153 .
- heater 150 includes one or more layers of printed glass 156 on top surface 152 a of ceramic substrate 152 .
- glass layer 156 covers resistive trace 160 and portions of conductive traces 162 a , 162 b in order to electrically insulate such features to prevent electric shock or arcing.
- glass layer 156 covers resistive trace 160 and adjacent portions of ceramic substrate 152 such that glass layer 156 forms the majority of the top surface of heater 150 facing heating plate 145 .
- An overall thickness of glass layer 156 may range from, for example, 35-45 microns.
- heater 150 also includes one or more layers of printed glass 159 on bottom surface 152 b of ceramic substrate 152 to minimize camber.
- the borders of glass layer 159 are shown in dashed line in FIG. 5 .
- glass layer 159 does not cover thermistor 170 and some portions of conductive traces 172 a , 172 b because the relatively low voltage (in comparison with the voltages applied to resistive trace 160 ) applied to such features presents a lower risk of electric shock or arcing.
- An overall thickness of glass layer 159 may range from, for example, 35-45 microns.
- heater 150 is fabricated by fiber laser scribing the perimeter of heater 150 to further increase thermal shock resistance. Fiber laser scribing tends to provide a more uniform singulation surface having fewer microcracks along the separated edge in comparison with conventional carbon dioxide laser scribing.
- Heater 150 may be constructed by way of thick film printing.
- resistive trace 160 is printed on fired (not green state) ceramic substrate 152 , which includes selectively applying a paste containing resistor material to top surface 152 a of ceramic substrate 152 through a patterned mesh screen with a squeegee or the like.
- the printed resistor is then allowed to settle on ceramic substrate 152 at room temperature.
- the ceramic substrate 152 having the printed resistor is then heated at, for example, approximately 140-160 degrees Celsius for a total of approximately 30 minutes, including approximately 10-15 mins at peak temperature and the remaining time ramping up to and down from the peak temperature, in order to dry the resistor paste and to temporarily fix resistive trace 160 in position.
- the ceramic substrate 152 having temporary resistive trace 160 is then heated at, for example, approximately 850 degrees Celsius for a total of approximately one hour, including approximately 10 minutes at peak temperature and the remaining time ramping up to and down from the peak temperature, in order to permanently fix resistive trace 160 in position.
- Conductive traces 162 a , 162 b are then printed on top surface 152 a of ceramic substrate 152 , which includes selectively applying a paste containing conductor material in the same manner as the resistor material.
- the ceramic substrate 152 having the printed resistor and conductor is then allowed to settle, dried and fired in the same manner as discussed above with respective to resistive trace 160 in order to permanently fix conductive traces 162 a , 162 b in position.
- Glass layer(s) 156 on top surface 152 a are then printed in substantially the same manner as the resistors and conductors, including allowing the glass layer(s) 156 to settle as well as drying and firing the glass layer(s) 156 .
- glass layer(s) 156 are fired at a peak temperature of approximately 810 degrees Celsius, slightly lower than the resistors and conductors.
- Conductive traces 172 a , 172 b for thermistor 170 are printed on bottom surface 152 b of ceramic substrate 152 in substantially the same manner as conductive traces 162 a , 162 b
- glass layer(s) 159 are printed on bottom surface 152 b of ceramic substrate 152 in substantially the same manner as glass layer(s) 156 .
- Thermistor 170 is then mounted to ceramic substrate 152 in a finishing operation with the terminals of thermistor 170 directly welded to conductive traces 172 a , 172 b.
- Thick film printing resistive trace 160 and conductive traces 162 a , 162 b on fired ceramic substrate 152 provides more uniform resistive and conductive traces in comparison with ceramic heaters having resistive and conductive traces printed on green state ceramic.
- the improved uniformity of resistive trace 160 and conductive traces 162 a , 162 b provides more uniform heating across heating plate 145 as well as more predictable heating of heater 150 .
- heater 150 may have other forms and shapes as desired.
- a heater 1150 may have a circular shape according to one example embodiment.
- Thermistor 170 is disposed on a surface of ceramic substrate 152 opposite the surface along which resistive trace 160 is disposed in the embodiment shown in FIG. 5 , but thermistor 170 and/or its corresponding conductive traces may be disposed on the same side of ceramic substrate 152 as resistive trace 160 so long as they do not interfere with the positioning of resistive trace 160 and conductive traces 162 a , 162 b .
- a thermistor 1170 is positioned on the same surface as resistive trace 160 (e.g., top surface 1152 a of ceramic substrate 1152 ).
- corresponding conductive traces of thermistor 170 may be disposed on the bottom surface (opposite top surface 1152 a ) of ceramic substrate 1152 while thermistor 1170 is positioned on top surface 1152 a thereof.
- heater 150 may include vias that are formed as through-holes substantially filled with conductive material extending through ceramic substrate 1152 from top surface 1152 a to the bottom surface of ceramic substrate 1152 in order to electrically connect the terminals of thermistor 1170 on top surface 1152 a to their corresponding conductive traces on the bottom surface.
- the heater of the present disclosure may include resistive and conductive traces in many different patterns and locations on ceramic substrate 152 , including to resistive traces on one or more of the exterior surfaces (top surface and/or bottom surface) of ceramic substrate 152 and/or an intermediate surface of ceramic substrate 152 , as desired.
- Other components e.g., a thermistor
- FIG. 8 shows a cooking vessel 120 suitable for use with heater assembly 140 according to one example embodiment.
- cooking vessel 120 includes an inner shell 125 and an outer shell 130 .
- An outside surface 125 b of inner shell 125 forms food receptacle 121 of cooking vessel 120 .
- Inner shell 125 and outer shell 130 have corresponding side walls 126 , 131 and corresponding bottom walls 127 , 132 separated by a gap 129 to form a dual-wall vessel.
- bottom wall 132 of outer shell 130 has a slightly concave outside surface 130 b that substantially matches domed upper surface 147 of heating plate 145 .
- heating plate 145 having a domed upper surface 147 in contact with a concave outside surface 130 b of the bottom wall 132 of cooking vessel 120 helps reduce bowing of bottom wall 132 of cooking vessel 120 during heating in comparison with a cooking vessel having a fiat bottom surface in contact with a flat top surface of a heating plate or heater. This, in turn, helps upper surface 147 of heating plate 145 maintain consistent contact with outside surface 130 b of the bottom wall 132 of cooking vessel 120 for heat transfer.
- Inner shell 125 and outer shell 130 are integrally joined or welded, e.g., at rim 122 , forming a sealed volume between inner and outer shells 125 , 130 that includes gap 129 . In some embodiments, the sealed volume is formed under reduced pressure relative to atmospheric pressure, such as a partial vacuum.
- a heat pipe 134 is provided between inner and outer shells 125 , 130 , including between side walls 126 , 131 and between bottom walls 127 , 132 .
- corresponding inside surfaces 125 a , 130 a of inner and outer shells 125 , 130 are lined with wick structures 135 containing a relatively small amount of working fluid, such as water.
- the wick structures 135 may be constructed from materials that allow capillary action of the working fluid within the sealed volume as discussed below.
- FIGS. 9A-9C various example wick structures for use with cooking vessel 120 are illustrated. Each of FIGS. 9A-9C is a cross-sectional view of cooking vessel 120 taken along line 9 - 9 in FIG. 8 .
- the wick structure includes sintered or arc sprayed metal 135 a , such as copper or aluminum, provided on inside surfaces 125 a , 130 a of inner and outer shells 125 , 130 .
- a screen or wire mesh 135 b is provided on each of the inside surfaces 125 a , 130 a of inner and outer shells 125 , 130 to form the wick structure.
- grooves 135 c are formed on each of the inside surfaces 125 a , 130 a of inner and outer shells 125 , 130 to provide the wick structure.
- Each groove 135 c extends substantially vertically along a respective side wall 126 , 131 and may continue substantially horizontally along a respective bottom wall 127 , 132 . While the example embodiments illustrated include a heat pipe 134 that includes one or more wick structures 135 and a working fluid, in other embodiments, heat pipe 134 includes a working fluid (e.g., water) contained between inner and outer shells 125 , 130 , but no wick structure.
- a working fluid e.g., water
- the working fluid cycles between an evaporation zone 180 near or around the lower region of cooking vessel 120 that is directly heated by heating plate 145 and a condensation zone 190 around the upper region of cooking vessel 120 .
- the working fluid within the evaporation zone 180 e.g., working fluid within the wick structures 135 between bottom walls 127 , 132 of inner and outer shells 125 , 130 and between side walls 126 , 131 of inner and outer shells 125 , 130 in the lower region of cooking vessel 120
- vapor 138 travels from the evaporation zone 180 to the condensation zone 190 along the gap 129 between wick structures 135 .
- vapor 138 arrives at the condensation zone 190 , it condenses back into liquid form releasing latent heat 185 through inner and outer shells 125 , 130 at the upper region of cooking vessel 120 .
- Condensed liquid 139 at the condensation zone 190 travels back to the evaporation zone 180 via wick structures 135 due to capillary action.
- the present disclosure provides a ceramic heater having a low thermal mass in comparison with the heaters of conventional cooking devices.
- a thick film printed resistive trace on a ceramic substrate provides reduced thermal mass in comparison with conventional wire coil heaters.
- the use of a thin heating plate, such as forged aluminum, also provides reduced thermal mass in comparison with the cast aluminum bodies of conventional wire coil heaters.
- the low thermal mass of the ceramic heater of the present disclosure allows the heater, in some embodiments, to heat to an effective temperature for use in a matter of seconds (e.g., less than 5 seconds), significantly faster than conventional wire coil heater cooking devices.
- the low thermal mass of the ceramic heater of the present disclosure also allows the heater, in some embodiments, to cool to a safe temperature after use in a matter of seconds (e.g., less than 5 seconds), again, significantly faster than conventional wire coil heater cooking devices.
- embodiments of the heater of the cooking device of the present disclosure operate at a more precise and more uniform temperature than conventional cooking devices because of the closed loop temperature control provided by the thermistor in combination with the relatively uniform thick film printed resistive and conductive traces.
- the low thermal mass of the ceramic heater permits greater energy efficiency in comparison with conventional wire coil heaters.
- the improved temperature control and temperature uniformity also improve the performance of the cooking device of the present disclosure. In this manner, embodiments of the cooking device of the present disclosure achieve high thermal and energy efficiency and high-end performance comparable to induction heating cooking devices, but at a greatly reduced cost in comparison with conventional induction heating cooking devices.
- the present disclosure further provides a heat pipe cooking vessel for use with the ceramic heater.
- the heat pipe structure within the cooking vessel provides improved thermal conductivity in comparison with conventional aluminum or copper cooking vessels allowing for a more uniform temperature distribution and effective heat transfer. Coupled with the low thermal mass of the ceramic heater, the heat pipe cooking vessel provides improved temperature uniformity relative to conventional cooking devices.
- the ceramic heater and the cooking vessel of the present disclosure may be used separately from each other in different heating and/or cooking applications. That is, the ceramic heater of the present disclosure may be used with a conventional cooking vessel, and the heat pipe cooking vessel of the present disclosure may be used with conventional heaters.
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Abstract
Description
- This application claims priority to U.S. Provisional Patent Application Ser. No. 62/802,955, filed Feb. 8, 2019, entitled “Heat Pipe Cooking Vessel,” the content of which is hereby incorporated by reference in its entirety.
- The present disclosure relates generally to cooking devices and more particularly to a cooking device having a cooking vessel and a ceramic heater.
- Manufacturers of cooking devices, such as rice cookers, are continuously challenged to improve heating time and heating effectiveness. Most low-end rice cookers, for example, utilize a wire coil heater, such as nichrome wire, potted with ceramic cement inside a stainless steel sheath embedded inside a cast aluminum body. These heaters generate heat by passing electrical current through the nichrome wire. These types of heaters often suffer from long warmup and cooldown times due to the high thermal mass provided by the electrical insulation materials and the relatively large metal components. Furthermore, cooking vessels used with wire coil heaters typically have relatively low thermal mass resulting in poor distribution of heat within the cooking vessel.
- Some high-end rice cookers utilize induction heaters to directly warm the cooking vessel instead of relying on convection or thermal conduction. Induction rice cookers use induction heating where current is passed through a metal coil to create a magnetic field. The cooking vessel is positioned within the magnetic field to induce electrical current in the cooking vessel which, in turn, generates heat. With induction heating, the heating temperature may be controlled by adjusting the strength of the magnetic field allowing for shorter warmup and cooldown times to be achieved. However, induction heaters are generally expensive due to the cost of the electrical materials and components, and the control systems for induction heaters are relatively complex and generally expensive as a result.
- Accordingly, a cost-effective cooking device having improved thermal efficiency is desired.
- A cooking device according to one example embodiment includes a base having a top surface positioned to contact a cooking vessel configured to hold food during cooking. The base includes a heater having a ceramic substrate and an electrically resistive trace on an exterior surface of the ceramic substrate. The heater is positioned to supply heat generated by applying an electric current to the electrically resistive trace to the top surface of the base for heating the cooking vessel to heat food in the cooking vessel. In some embodiments, the electrically resistive trace includes an electrical resistor material thick film printed on the exterior surface of the ceramic substrate. In some embodiments, the electrically resistive trace is positioned on a top surface of the ceramic substrate that faces upward toward the top surface of the base.
- Embodiments include those wherein the heater includes a thermistor that is positioned on the ceramic substrate and in electrical communication with control circuitry of the heater for providing feedback regarding a temperature of the heater to the control circuitry of the heater. In some embodiments, the thermistor is positioned on a bottom surface of the ceramic substrate that faces away from the top surface of the base.
- Embodiments include those wherein the base includes a heating plate that forms the top surface of the base. The heating plate is positioned in contact with the heater to transfer heat from the heater to the top surface of the base for heating the cooking vessel to heat food in the cooking vessel. In some embodiments, the heating plate includes a domed top surface for contacting a concave bottom surface of the cooking vessel.
- Embodiments include those wherein the ceramic substrate has a polygonal shape. In some embodiments, the ceramic substrate has an octagonal shape.
- Embodiments include those wherein the electrically resistive trace extends in a serpentine pattern across the exterior surface of the ceramic substrate. In some embodiments, the serpentine pattern of the electrically resistive trace has a generally circular outer perimeter.
- A cooking device according to another example embodiment includes a housing having a receptacle and a base positioned along a bottom of the receptacle. A cooking vessel is removably positionable within the receptacle for containing food to be cooked. The cooking vessel contacts the base when the cooking vessel is positioned within the receptacle. The base includes a heater having a ceramic substrate and an electrical resistor material thick film printed on a surface of the ceramic substrate. The heater is positioned to supply heat generated by applying an electric current to the electrical resistor material to the cooking vessel when the cooking vessel is positioned within the receptacle.
- A heater for use with a cooking device according to one example embodiment includes a ceramic substrate and an electrically resistive trace thick film printed on an exterior face of the ceramic substrate. The electrically resistive trace extends in a serpentine pattern across the exterior face of the ceramic substrate from a first end of the electrically resistive trace to a second end of the electrically resistive trace. The serpentine pattern of the electrically resistive trace has a generally circular outer perimeter. The heater also includes a first electrically conductive trace electrically connected to the first end of the electrically resistive trace and a second electrically conductive trace electrically connected to the second end of the electrically resistive trace. The first and second electrically conductive traces form respective first and second terminals providing respective first and second electrical connections for completing a circuit formed by the first and second electrically conductive traces and the electrically resistive trace. Some embodiments include one or more glass layers on the exterior face of the ceramic substrate that cover the electrically resistive trace electrically insulating the electrically resistive trace. Some embodiments include a thermistor positioned on a second exterior face of the ceramic substrate that is opposite the exterior face of the ceramic substrate on which the electrically resistive trace is positioned for providing feedback regarding a temperature of the heater to control circuitry of the heater. Embodiments include those wherein the ceramic substrate has a polygonal shape. In some embodiments, the ceramic substrate has an octagonal shape.
- The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present disclosure and together with the description serve to explain the principles of the present disclosure.
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FIG. 1 is a perspective view of a cooking device according to one example embodiment. -
FIG. 2 is a schematic diagram of the cooking device according to one example embodiment. -
FIG. 3 is an exploded perspective view of a heater assembly of the cooking device according to one example embodiment. -
FIGS. 4 and 5 are plan views of a top surface and a bottom surface, respectively, of a heater of the heater assembly shown inFIG. 3 . -
FIG. 6 is a cross-sectional view of the heater shown inFIGS. 4 and 5 taken along line 6-6 inFIG. 4 . -
FIG. 7 is a plan view of a top surface of a heater according to another example embodiment. -
FIG. 8 is a cross-sectional view of a cooking vessel of the cooking device employing a heat pipe according to one example embodiment. -
FIGS. 9A-9C are cross-sectional views of the cooking vessel shown inFIG. 8 taken along line 9-9 inFIG. 8 illustrating various example wick structures of the heat pipe. - In the following description, reference is made to the accompanying drawings where like numerals represent like elements. The embodiments are described in sufficient detail to enable those skilled in the art to practice the present disclosure. It is to be understood that other embodiments may be utilized and that process, electrical, and mechanical changes, etc., may be made without departing from the scope of the present disclosure. Examples merely typify possible variations. Portions and features of some embodiments may be included in or substituted for those of others. The following description, therefore, is not to be taken in a limiting sense and the scope of the present disclosure is defined only by the appended claims and their equivalents.
- Referring now to the drawings and particularly to
FIG. 1 , acooking device 100 is shown according to one example embodiment. In the example embodiment illustrated,cooking device 100 includes a rice cooker. However,cooking device 100 may also include a pressure cooker, a steam cooker, etc.Cooking device 100 includes ahousing 102, acooking vessel 120, alid 105, aheater assembly 140, and auser interface 109.Housing 102 includes an upper portion having areceptacle 103 for receivingcooking vessel 120 and a lower portion within whichheater assembly 140 is mounted. In the embodiment illustrated,heater assembly 140 forms a receiving base ofreceptacle 103 such thatcooking vessel 120 contacts and rests on top ofheater assembly 140 when cookingvessel 120 is positioned withinreceptacle 103 so that heat generated byheater assembly 140heats cooking vessel 120. -
Cooking vessel 120 is generally a container (e.g., a bowl) having afood receptacle 121 in which food substances to be cooked, such as rice and water, are contained. That is,food receptacle 121 ofcooking vessel 120 directly contacts and retains the food being cooked.Cooking vessel 120 may be composed of, for example, a metal having high thermal conductivity, such as stainless steel, aluminum or copper.Lid 105 covers the opening at arim 122 ofcooking vessel 120.Lid 105 includes ahandle 107 preferably composed of a material having low thermal conductivity to provide a safe surface for the user to hold when usinglid 105.User interface 109 is provided on a front portion ofhousing 102.User interface 109 may include one or more buttons, dials, knobs, etc. for receiving user input and/or a display or indicator lights for providing information about the functioning and status ofcooking device 100 to a user.Cooking device 100 also includes apower cord 112 for connectingcooking device 100 to anexternal power source 114. - In one embodiment, during use,
food receptacle 121 ofcooking vessel 120 holds water and rice to cook, andheater 140 transfers heat tocooking vessel 120 to bring the water to boil. Once the water reaches a steady boil, the temperature ofcooking vessel 120 remains generally stable. Once all of the water incooking vessel 120 is absorbed by the rice and/or evaporated, the temperature ofcooking vessel 120 tends to increase, triggering a mechanism insidecooking device 100 to either turnheater assembly 140 off or to switch to a reduced temperature warming cycle intended to keep the food incooking vessel 120 warm. - With reference to
FIG. 2 , a schematic depiction ofcooking device 100 is shown according to one example embodiment.Cooking device 100 includesheater assembly 140 including aheater 150 and aheating plate 145.Heater 150 includes asubstrate 152 to which at least oneresistive trace 160 is secured. Heat is generated when electrical current provided bypower source 114 is passed throughresistive trace 160. When cookingvessel 120 is disposed inreceptacle 103,cooking vessel 120 contacts and rests on top ofheating plate 145.Heating plate 145 is positioned in contact with, or in very close proximity to,heater 150 in order to transfer heat fromheater 150 tocooking vessel 120. In some embodiments, thermal grease is applied betweenheater 150 andheating plate 145 to facilitate physical contact and heat transfer betweenheater 150 andheating plate 145. In some embodiments, a gap filler (e.g., silicon gap filler) or pad (e.g., graphite gap pad) is positioned betweenheater 150 andheating plate 145 to facilitate heat transfer betweenheater 150 andheating plate 145.Heating plate 145 is composed of, for to example, a metal having high thermal conductivity, such as forged aluminum. -
Cooking device 100 includescontrol circuitry 115 configured to control the temperature ofheater 150 by selectively opening or closing a circuit supplying electrical current toresistive trace 160. Open loop or, preferably, closed loop control may be utilized as desired. In the embodiment illustrated, atemperature sensor 170, such as a thermistor, is coupled tosubstrate 152 for sensing the temperature ofheater 150 and permitting closed loop control ofheater 150 bycontrol circuitry 115.Control circuitry 115 may include a microprocessor, a microcontroller, an application-specific integrated circuit, and/or other form integrated circuit.User interface 109 is communicatively coupled to controlcircuitry 115 via acommunications link 110. - In the embodiment illustrated in
FIG. 2 ,control circuitry 115 includes aswitch 117 connected between one end ofresistive trace 160 and a first terminal 114 a ofpower source 114.Switch 117 may be, for example, a mechanical switch, an electronic switch, a relay, or other switching device. The other end ofresistive trace 160 is connected to asecond terminal 114 b ofpower source 114. The temperature ofheater 150 is controlled by measuring the temperature ofsubstrate 152 bytemperature sensor 170 held in contact withsubstrate 152 and feeding temperature information fromtemperature sensor 170 to controlcircuitry 115 which, in turn, controls switch 117 to selectively supply power toresistive trace 160 based on the temperature information. Whenswitch 117 is closed, current flows throughresistive trace 160 to generate heat fromheater 150. Whenswitch 117 is opened, no current flows throughresistive trace 160 to pause or stop heat generation fromheater 150. In some embodiments,control circuitry 115 may include power control logic and/or other circuitries for controlling the amount of power delivered toresistive trace 160 to permit adjustment of the amount of heat generated byheater 150 within a desired range of temperatures. For example, in some embodiments, when the temperature ofheater 150 is low (e.g., under 100 degrees Celsius),heater 150 is supplied with 50% power and then gradually stepped up from 50% to 100% as the temperature ofheater 150 increases. -
FIG. 3 showsheater assembly 140 includingheating plate 145 andheater 150 according to one example embodiment.FIG. 4 shows a top view ofheater 150, andFIG. 5 shows a bottom view ofheater 150. In the example embodiment illustrated,heating plate 145 is formed as a circular disk having a domed upper surface 147 (also shown inFIG. 2 with exaggerated scale for illustration purposes). In one embodiment,heating plate 145 has a diameter of about 162 mm, a central portion having a thickness of about 5 mm, and a circumferential edge having a thickness of about 1 mm. In other embodiments,heating plate 145 may have other shapes as long asheating plate 145 is positioned to spread heat fromheater 150 across the bottom surface ofcooking vessel 120. The thermal conductivity and relative thinness ofheating plate 145 result in a relatively low thermal mass, which reduces the amount of time required to heat andcool heating plate 145 and, in turn,cooking vessel 120. -
Heater 150 includessubstrate 152 constructed from ceramic or the like, such as aluminum oxide (e.g., commercially available 96% aluminum oxide ceramic). Hereinafter,substrate 152 is referred to asceramic substrate 152. In some embodiments,heater 150 may include one or more layers ofceramic substrate 152. Whereheater 150 includes a single layer ofceramic substrate 152, a thickness ofceramic substrate 152 may range from, for example, 0.5 mm to 1.5 mm, such as 1.0 mm. Whereheater 150 includes multiple layers ofceramic substrate 152, each layer may have a thickness ranging from, for example, 0.5 mm to 1.0 mm, such as 0.635 mm. In the embodiment illustrated,ceramic substrate 152 is octagonal in shape having an incircle diameter d of about 147 mm. However,ceramic substrate 152 may take other suitable shapes depending on the application, such as, for example, circular, hexagonal, square, etc. In general, the octagonal shape illustrated is easier to reliably manufacture on a commercial basis than, for example, a circular shape. -
Ceramic substrate 152 includes atop surface 152 a that facesheating plate 145 and abottom surface 152 b oppositetop surface 152 a. In the embodiment illustrated,resistive trace 160 is positioned ontop surface 152 a ofceramic substrate 152.Resistive trace 160 includes afirst end 160 a and asecond end 160 b. In this embodiment, a pair ofconductive traces top surface 152 a. Conductive traces 162 a, 162 b are connected to first and second ends 160 a, 160 b ofresistive trace 160, respectively.Resistive trace 160 includes a suitable electrical resistor material such as, for example, silver palladium (e.g., blended 70/30 silver palladium). Conductive traces 162 a, 162 b include a suitable electrical conductor material such as, for example, silver platinum. In the embodiment illustrated,resistive trace 160 andconductive traces ceramic substrate 152 by way of thick film printing. For example,resistive trace 160 may include a resistor paste having a thickness of 10-13 microns when applied toceramic substrate 152, andconductive traces ceramic substrate 152.Resistive trace 160 forms the heating element ofheater 150, andconductive traces resistive trace 160 in order to supply an electrical current toresistive trace 160 to generate heat. - In the example embodiment illustrated,
resistive trace 160 follows a serpentine pattern extending fromfirst end 160 a tosecond end 160 b alongtop surface 152 a ofceramic substrate 152. In this embodiment, the serpentine pattern formed byresistive trace 160 has a generally circularouter perimeter 161. Conductive traces 162 a, 162 b each form arespective terminal heater 150. Cables orwires respective terminals resistive trace 160 andconductive traces control circuitry 115 andpower source 114 in order to selectively close the circuit formed byresistive trace 160 andconductive traces Conductive trace 162 a directly contacts first end 160 a ofresistive trace 160, andconductive trace 162 b directly contacts second end 160 b ofresistive trace 160. Conductive traces 162 a, 162 b both extend along anextension portion 155 ofceramic substrate 152 that extends from anedge 157 ofceramic substrate 152 in the example embodiment illustrated, but conductive traces 162 a, 162 b may be positioned in other suitable locations onceramic substrate 152 as desired. Portions of first and second ends 160 a, 160 b ofresistive trace 160 obscured beneathconductive traces FIG. 4 are shown in dotted line. In this embodiment, current input toheater 150 at, for example, terminal 163 a by way ofconductive trace 162 a passes through, in order,resistive trace 160 andconductive trace 162 b where it is output fromheater 150 atterminal 163 b. Current input toheater 150 atterminal 163 b travels in reverse along the same path. - In some embodiments,
heater 150 includestemperature sensor 170, also referred to asthermistor 170, positioned in close proximity to a surface ofheater 150 in order to provide feedback regarding the temperature ofheater 150 to controlcircuitry 115. In the embodiment shown,thermistor 170 is positioned onbottom surface 152 b ofceramic substrate 152. In the example embodiment illustrated,thermistor 170 is welded directly tobottom surface 152 b ofceramic substrate 152. In this embodiment,heater 150 also includes a pair ofconductive traces thermistor 170. Eachconductive trace respective terminal edge 158 ofceramic substrate 152. Cables orwires terminals thermistor 170 to, for example,control circuitry 115 in order to provide closed loop control ofheater 150. In the embodiment illustrated,thermistor 170 is positioned at a central location ofbottom surface 152 b ofceramic substrate 152. However,thermistor 170 and its correspondingconductive traces bottom surface 152 b ofceramic substrate 152. - In some embodiments,
heater 150 also includes a thermal cutoff (not shown), such as a bi-metal thermal cutoff, in contact withceramic substrate 152 and connected in series with the heating circuit formed byresistive trace 160 andconductive traces resistive trace 160 andconductive traces heater 150. -
FIG. 6 is a cross-sectional view ofheater 150 taken along line 6-6 inFIG. 4 . As shown,heater 150 includesresistive trace 160 andconductive traces ceramic substrate 152.FIG. 6 depicts a single layer ofceramic substrate 152. However,ceramic substrate 152 may include multiple layers as depicted by dashedline 153. In the embodiment illustrated,heater 150 includes one or more layers of printedglass 156 ontop surface 152 a ofceramic substrate 152. In the embodiment illustrated,glass layer 156 coversresistive trace 160 and portions ofconductive traces glass layer 156 are shown in dashed line inFIG. 4 . In this embodiment,glass layer 156 coversresistive trace 160 and adjacent portions ofceramic substrate 152 such thatglass layer 156 forms the majority of the top surface ofheater 150 facingheating plate 145. An overall thickness ofglass layer 156 may range from, for example, 35-45 microns. - In the embodiment illustrated,
heater 150 also includes one or more layers of printedglass 159 onbottom surface 152 b ofceramic substrate 152 to minimize camber. The borders ofglass layer 159 are shown in dashed line inFIG. 5 . In this embodiment,glass layer 159 does not coverthermistor 170 and some portions ofconductive traces glass layer 159 may range from, for example, 35-45 microns. - In addition to providing electrical insulation, laminating the ceramic heater of the present disclosure with
glass layers heater 150 is fabricated by fiber laser scribing the perimeter ofheater 150 to further increase thermal shock resistance. Fiber laser scribing tends to provide a more uniform singulation surface having fewer microcracks along the separated edge in comparison with conventional carbon dioxide laser scribing. -
Heater 150 may be constructed by way of thick film printing. For example, in one embodiment,resistive trace 160 is printed on fired (not green state)ceramic substrate 152, which includes selectively applying a paste containing resistor material totop surface 152 a ofceramic substrate 152 through a patterned mesh screen with a squeegee or the like. The printed resistor is then allowed to settle onceramic substrate 152 at room temperature. Theceramic substrate 152 having the printed resistor is then heated at, for example, approximately 140-160 degrees Celsius for a total of approximately 30 minutes, including approximately 10-15 mins at peak temperature and the remaining time ramping up to and down from the peak temperature, in order to dry the resistor paste and to temporarily fixresistive trace 160 in position. Theceramic substrate 152 having temporaryresistive trace 160 is then heated at, for example, approximately 850 degrees Celsius for a total of approximately one hour, including approximately 10 minutes at peak temperature and the remaining time ramping up to and down from the peak temperature, in order to permanently fixresistive trace 160 in position. Conductive traces 162 a, 162 b are then printed ontop surface 152 a ofceramic substrate 152, which includes selectively applying a paste containing conductor material in the same manner as the resistor material. Theceramic substrate 152 having the printed resistor and conductor is then allowed to settle, dried and fired in the same manner as discussed above with respective toresistive trace 160 in order to permanently fixconductive traces top surface 152 a are then printed in substantially the same manner as the resistors and conductors, including allowing the glass layer(s) 156 to settle as well as drying and firing the glass layer(s) 156. In one embodiment, glass layer(s) 156 are fired at a peak temperature of approximately 810 degrees Celsius, slightly lower than the resistors and conductors. Conductive traces 172 a, 172 b forthermistor 170 are printed onbottom surface 152 b ofceramic substrate 152 in substantially the same manner asconductive traces bottom surface 152 b ofceramic substrate 152 in substantially the same manner as glass layer(s) 156.Thermistor 170 is then mounted toceramic substrate 152 in a finishing operation with the terminals ofthermistor 170 directly welded toconductive traces - Thick film printing
resistive trace 160 andconductive traces ceramic substrate 152 provides more uniform resistive and conductive traces in comparison with ceramic heaters having resistive and conductive traces printed on green state ceramic. The improved uniformity ofresistive trace 160 andconductive traces heating plate 145 as well as more predictable heating ofheater 150. - While the example embodiment illustrated in
FIGS. 3-5 includesheater 150 having an octagonal shape, in other embodiments,heater 150 may have other forms and shapes as desired. For example, with reference toFIG. 7 , aheater 1150 may have a circular shape according to one example embodiment.Thermistor 170 is disposed on a surface ofceramic substrate 152 opposite the surface along whichresistive trace 160 is disposed in the embodiment shown inFIG. 5 , butthermistor 170 and/or its corresponding conductive traces may be disposed on the same side ofceramic substrate 152 asresistive trace 160 so long as they do not interfere with the positioning ofresistive trace 160 andconductive traces FIG. 7 , athermistor 1170 is positioned on the same surface as resistive trace 160 (e.g.,top surface 1152 a of ceramic substrate 1152). In some embodiments, corresponding conductive traces ofthermistor 170 may be disposed on the bottom surface (oppositetop surface 1152 a) ofceramic substrate 1152 whilethermistor 1170 is positioned ontop surface 1152 a thereof. In this embodiment,heater 150 may include vias that are formed as through-holes substantially filled with conductive material extending throughceramic substrate 1152 fromtop surface 1152 a to the bottom surface ofceramic substrate 1152 in order to electrically connect the terminals ofthermistor 1170 ontop surface 1152 a to their corresponding conductive traces on the bottom surface. - It will be appreciated that the example embodiments illustrated and discussed above are not exhaustive and that the heater of the present disclosure may include resistive and conductive traces in many different patterns and locations on
ceramic substrate 152, including to resistive traces on one or more of the exterior surfaces (top surface and/or bottom surface) ofceramic substrate 152 and/or an intermediate surface ofceramic substrate 152, as desired. Other components (e.g., a thermistor) may be positioned on either the top surface or the bottom surface of the heater as desired, including on the same surface as the resistive traces or an opposite surface. -
FIG. 8 shows acooking vessel 120 suitable for use withheater assembly 140 according to one example embodiment. In the embodiment illustrated,cooking vessel 120 includes aninner shell 125 and anouter shell 130. Anoutside surface 125 b ofinner shell 125 formsfood receptacle 121 ofcooking vessel 120.Inner shell 125 andouter shell 130 havecorresponding side walls bottom walls gap 129 to form a dual-wall vessel. In this embodiment,bottom wall 132 ofouter shell 130 has a slightly concaveoutside surface 130 b that substantially matches domedupper surface 147 ofheating plate 145. The use of aheating plate 145 having a domedupper surface 147 in contact with a concaveoutside surface 130 b of thebottom wall 132 ofcooking vessel 120 helps reduce bowing ofbottom wall 132 ofcooking vessel 120 during heating in comparison with a cooking vessel having a fiat bottom surface in contact with a flat top surface of a heating plate or heater. This, in turn, helpsupper surface 147 ofheating plate 145 maintain consistent contact withoutside surface 130 b of thebottom wall 132 ofcooking vessel 120 for heat transfer.Inner shell 125 andouter shell 130 are integrally joined or welded, e.g., atrim 122, forming a sealed volume between inner andouter shells gap 129. In some embodiments, the sealed volume is formed under reduced pressure relative to atmospheric pressure, such as a partial vacuum. - In the example embodiment illustrated, a
heat pipe 134 is provided between inner andouter shells side walls bottom walls outer shells wick structures 135 containing a relatively small amount of working fluid, such as water. Thewick structures 135 may be constructed from materials that allow capillary action of the working fluid within the sealed volume as discussed below. InFIGS. 9A-9C , various example wick structures for use withcooking vessel 120 are illustrated. Each ofFIGS. 9A-9C is a cross-sectional view ofcooking vessel 120 taken along line 9-9 inFIG. 8 . In the embodiment shown inFIG. 9A , the wick structure includes sintered or arc sprayedmetal 135 a, such as copper or aluminum, provided oninside surfaces outer shells FIG. 9B , a screen orwire mesh 135 b is provided on each of theinside surfaces outer shells FIG. 9C ,grooves 135 c are formed on each of theinside surfaces outer shells groove 135 c extends substantially vertically along arespective side wall respective bottom wall heat pipe 134 that includes one ormore wick structures 135 and a working fluid, in other embodiments,heat pipe 134 includes a working fluid (e.g., water) contained between inner andouter shells - In one embodiment, during use, the working fluid cycles between an
evaporation zone 180 near or around the lower region ofcooking vessel 120 that is directly heated byheating plate 145 and acondensation zone 190 around the upper region ofcooking vessel 120. In particular, as cookingvessel 120 is heated by heater assembly 140 (e.g., byoutside surface 130 b ofbottom wall 132 ofouter shell 130 receiving heat from heater assembly 140) the working fluid within the evaporation zone 180 (e.g., working fluid within thewick structures 135 betweenbottom walls outer shells side walls outer shells vapor 138. Driven by pressure and temperature differences between the lower (hotter) region and upper (cooler) region,vapor 138 travels from theevaporation zone 180 to thecondensation zone 190 along thegap 129 betweenwick structures 135. Whenvapor 138 arrives at thecondensation zone 190, it condenses back into liquid form releasinglatent heat 185 through inner andouter shells cooking vessel 120. Condensed liquid 139 at thecondensation zone 190 travels back to theevaporation zone 180 viawick structures 135 due to capillary action. As the vaporization and condensation cycle repeats, heat is transferred from locations near the heat source to the rest of the sealed volume of cooking vessel 120 (i.e., from betweenbottom walls outer shells side walls outer shells 125, 130) resulting in an improved temperature uniformity withincooking vessel 120. - The present disclosure provides a ceramic heater having a low thermal mass in comparison with the heaters of conventional cooking devices. In particular, a thick film printed resistive trace on a ceramic substrate provides reduced thermal mass in comparison with conventional wire coil heaters. The use of a thin heating plate, such as forged aluminum, also provides reduced thermal mass in comparison with the cast aluminum bodies of conventional wire coil heaters. The low thermal mass of the ceramic heater of the present disclosure allows the heater, in some embodiments, to heat to an effective temperature for use in a matter of seconds (e.g., less than 5 seconds), significantly faster than conventional wire coil heater cooking devices. The low thermal mass of the ceramic heater of the present disclosure also allows the heater, in some embodiments, to cool to a safe temperature after use in a matter of seconds (e.g., less than 5 seconds), again, significantly faster than conventional wire coil heater cooking devices.
- Further, embodiments of the heater of the cooking device of the present disclosure operate at a more precise and more uniform temperature than conventional cooking devices because of the closed loop temperature control provided by the thermistor in combination with the relatively uniform thick film printed resistive and conductive traces. The low thermal mass of the ceramic heater permits greater energy efficiency in comparison with conventional wire coil heaters. The improved temperature control and temperature uniformity also improve the performance of the cooking device of the present disclosure. In this manner, embodiments of the cooking device of the present disclosure achieve high thermal and energy efficiency and high-end performance comparable to induction heating cooking devices, but at a greatly reduced cost in comparison with conventional induction heating cooking devices.
- The present disclosure further provides a heat pipe cooking vessel for use with the ceramic heater. The heat pipe structure within the cooking vessel provides improved thermal conductivity in comparison with conventional aluminum or copper cooking vessels allowing for a more uniform temperature distribution and effective heat transfer. Coupled with the low thermal mass of the ceramic heater, the heat pipe cooking vessel provides improved temperature uniformity relative to conventional cooking devices.
- While the example embodiment discussed above includes a ceramic heater used in conjunction with a heat pipe cooking vessel, it will be appreciated that the ceramic heater and the cooking vessel of the present disclosure may be used separately from each other in different heating and/or cooking applications. That is, the ceramic heater of the present disclosure may be used with a conventional cooking vessel, and the heat pipe cooking vessel of the present disclosure may be used with conventional heaters.
- The foregoing description illustrates various aspects of the present disclosure. It is not intended to be exhaustive. Rather, it is chosen to illustrate the principles of the present disclosure and its practical application to enable one of ordinary skill in the art to utilize the present disclosure, including its various modifications that naturally follow. All modifications and variations are contemplated within the scope of the present disclosure as determined by the appended claims. Relatively apparent modifications include combining one or more features of various embodiments with features of other embodiments.
Claims (26)
Priority Applications (7)
Application Number | Priority Date | Filing Date | Title |
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US16/782,318 US20200253409A1 (en) | 2019-02-08 | 2020-02-05 | Cooking device having a cooking vessel and a ceramic heater |
PCT/US2020/016927 WO2020163556A1 (en) | 2019-02-08 | 2020-02-06 | Cooking device having a cooking vessel and a ceramic heater |
EP20752674.0A EP3920755A4 (en) | 2019-02-08 | 2020-02-06 | Cooking device having a cooking vessel and a ceramic heater |
CA3127692A CA3127692A1 (en) | 2019-02-08 | 2020-02-06 | Cooking device having a cooking vessel and a ceramic heater |
JP2021544775A JP7504896B2 (en) | 2019-02-08 | 2020-02-06 | Cooking device having a cooking vessel and a ceramic heater - Patents.com |
CN202080012877.6A CN113395922A (en) | 2019-02-08 | 2020-02-06 | Cooking device with cooking container and ceramic heater |
US18/097,803 US20230148780A1 (en) | 2019-02-08 | 2023-01-17 | Cooking device having a cooking vessel and a ceramic heater |
Applications Claiming Priority (2)
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US201962802955P | 2019-02-08 | 2019-02-08 | |
US16/782,318 US20200253409A1 (en) | 2019-02-08 | 2020-02-05 | Cooking device having a cooking vessel and a ceramic heater |
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US18/097,803 Division US20230148780A1 (en) | 2019-02-08 | 2023-01-17 | Cooking device having a cooking vessel and a ceramic heater |
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US20200253409A1 true US20200253409A1 (en) | 2020-08-13 |
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US16/782,318 Abandoned US20200253409A1 (en) | 2019-02-08 | 2020-02-05 | Cooking device having a cooking vessel and a ceramic heater |
US16/782,327 Active 2041-07-23 US11666170B2 (en) | 2019-02-08 | 2020-02-05 | Cooking device having a cooking vessel and a ceramic heater |
US18/097,803 Pending US20230148780A1 (en) | 2019-02-08 | 2023-01-17 | Cooking device having a cooking vessel and a ceramic heater |
US18/139,658 Active US11998133B2 (en) | 2019-02-08 | 2023-04-26 | Cooking device having a cooking vessel and a ceramic heater |
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US16/782,327 Active 2041-07-23 US11666170B2 (en) | 2019-02-08 | 2020-02-05 | Cooking device having a cooking vessel and a ceramic heater |
US18/097,803 Pending US20230148780A1 (en) | 2019-02-08 | 2023-01-17 | Cooking device having a cooking vessel and a ceramic heater |
US18/139,658 Active US11998133B2 (en) | 2019-02-08 | 2023-04-26 | Cooking device having a cooking vessel and a ceramic heater |
Country Status (6)
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US (4) | US20200253409A1 (en) |
EP (1) | EP3920755A4 (en) |
JP (1) | JP7504896B2 (en) |
CN (1) | CN113395922A (en) |
CA (1) | CA3127692A1 (en) |
WO (1) | WO2020163556A1 (en) |
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US11998133B2 (en) | 2024-06-04 |
JP7504896B2 (en) | 2024-06-24 |
US20230148780A1 (en) | 2023-05-18 |
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CN113395922A (en) | 2021-09-14 |
US20230255386A1 (en) | 2023-08-17 |
US11666170B2 (en) | 2023-06-06 |
WO2020163556A1 (en) | 2020-08-13 |
EP3920755A1 (en) | 2021-12-15 |
JP2022520737A (en) | 2022-04-01 |
CA3127692A1 (en) | 2020-08-13 |
US20200253410A1 (en) | 2020-08-13 |
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