GB2171795A - Device for controlling the temperature of heating elements - Google Patents
Device for controlling the temperature of heating elements Download PDFInfo
- Publication number
- GB2171795A GB2171795A GB08604733A GB8604733A GB2171795A GB 2171795 A GB2171795 A GB 2171795A GB 08604733 A GB08604733 A GB 08604733A GB 8604733 A GB8604733 A GB 8604733A GB 2171795 A GB2171795 A GB 2171795A
- Authority
- GB
- United Kingdom
- Prior art keywords
- rod
- high heat
- zone
- temperature
- zones
- 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.)
- Granted
Links
- 238000010438 heat treatment Methods 0.000 title claims abstract description 19
- 238000010411 cooking Methods 0.000 claims abstract description 15
- 238000010521 absorption reaction Methods 0.000 claims abstract description 13
- 229910052751 metal Inorganic materials 0.000 claims abstract description 9
- 239000002184 metal Substances 0.000 claims abstract description 9
- 230000005855 radiation Effects 0.000 claims description 13
- 230000001276 controlling effect Effects 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 6
- 239000002241 glass-ceramic Substances 0.000 claims description 3
- 150000002739 metals Chemical class 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 claims description 2
- 238000009713 electroplating Methods 0.000 abstract description 3
- 238000007650 screen-printing Methods 0.000 abstract description 3
- 230000008021 deposition Effects 0.000 abstract description 2
- 229910052736 halogen Inorganic materials 0.000 description 14
- 150000002367 halogens Chemical class 0.000 description 14
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 4
- 230000006835 compression Effects 0.000 description 3
- 238000007906 compression Methods 0.000 description 3
- 229910052709 silver Inorganic materials 0.000 description 3
- 239000004332 silver Substances 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 101100298225 Caenorhabditis elegans pot-2 gene Proteins 0.000 description 1
- 229910017060 Fe Cr Inorganic materials 0.000 description 1
- 229910002544 Fe-Cr Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- UPHIPHFJVNKLMR-UHFFFAOYSA-N chromium iron Chemical compound [Cr].[Fe] UPHIPHFJVNKLMR-UHFFFAOYSA-N 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 229910000623 nickel–chromium alloy Inorganic materials 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
- H05B1/0216—Switches actuated by the expansion of a solid element, e.g. wire or rod
-
- 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
- H05B3/746—Protection, e.g. overheat cutoff, hot plate indicator
-
- 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
- H05B2213/04—Heating plates with overheat protection 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
- 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
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)
- Control Of Resistance Heating (AREA)
Abstract
A device for controlling the temperature of heating elements of electric cooking appliances is located between the heating element and a cooking surface and comprises a high thermal expansion rod (7) with zones of high heat reflection (30) and high heat absorption (31). The rod is arranged in a tube (8) having a low thermal expansion, one end of the rod being connected to a contact system used for controlling the temperature of the heating element. By varying the effective areas of the zones the switching temperature can easily be adjusted. The reflective zone (30) may be formed by a metal layer deposited by electroplating, screen printing or vapour deposition; alternatively it may comprise a sleeve (37). The absorption layer comprises the area of the rod not coated or covered. The reflective layer may comprise longitudinal, annular or helical strips. <IMAGE>
Description
SPECIFICATION
Device for controlling or limiting the temperature of radiation- or contact-type heating elements
Description of the Invention
The invention relates to a device for controlling or limiting the temperature of radiation- or contact-type heating elements of electric cooking appliances comprising cooking surfaces consisting of metal, glass-ceramics or similar, in which device, between the heating element and the cooking surface, at least one temperature sensor is arranged which is provided with a rod having high thermal expansion, which rod is provided with a layer which reflects heat radiation, and is arranged in a tube having a low thermal expansion, one end of the rod being connected to a contact system used for regulating or limiting the temperature of the heating element.
According to British Patent Specification 2132060, such a device is known, the heat being generated by halogen lamps. These are suitable for heating the cooking surface particularly rapidly and emit intensive heat radiation. The consequence of this is that the heat radiated by the halogen lamps is absorbed by the rod of the control device which, on the one hand, results in a very high switching rate and thus increased contact wear and, on the other hand, leads to a shift in the hotplate temperature to be controlled. To counter this disadvantage, the rod located between hotplate and halogen lamps was shielded, according to the literature quoted, by a suitable layer reflecting infra-red radiation, for example metal oxide. According to another known proposal the rod is enclosed in a small tube of suitable material.Although such shielding of the rod results in considerable reduction of the switching rate due to the reflection of heat radiation, the At, that is the temperature difference between switching-on and switching-off of the contact, reaches very high values as a result of which the mean temperature between switching-on and switching-off of the controller drops to inadmissibly low values.
For these reasons, the present invention has the objective of creating a device of the type initially described which excludes the possibility both of a very high switching rate and of an inaccurate temperature control due to a large At.
According to the invention, this objective is achieved by the fact that the rod is provided both with a zone, known in itself, of high heat reflection and with a zone of high heat absorption. As a result of such a combination of two zones having different heat radiation properties, accurate temperature control can be achieved with only little effort, even in the case of intense heat radiation from, for example, halogen lamps. The result of the division into zones is that a part of the heat radiation is predominantly reflected by the rod and a part is predominantly absorbed. The reflection and absorption values can be advantageously adapted in the simplest manner to the specific conditions of use by correspondingly increasing or decreasing the zones.Tests have shown that a predetermined At can be achieved by the zone combination according to the invention, in which connection, however, the switching rate can be quite considerably reduced in comparison with a completely uncoated rod while increasing the duration of operation of the device.
According to a preferred embodiment, provision is made for the zone of high heat absorption to be formed by the surface of the rod material. Such a measure advantageously results in simple production.
According to another advantageous variant of the invention, both zones are arranged so as to extend in the longitudinal direction of the rod and are distributed over the rod circumference. Such a construction of the zones has the advantage that a longitudinal displacement of the rod or of the device in relation to the halogen lamps, for example during adjustment, has no influence on the measurement result. Similarly, a twisting of the rod around its longitudinal axis has no disadvantageous effect. A further improvement in this sense can be achieved if, in development of the invention, the two zones are constructed so as to be strip-shaped and, if necessary, are distributed in different sequence over the rod circumference.
However, according to another embodiment of the invention, the zone of high heat reflection can also be advantageously annularly and/or helically arranged on the rod having a high heat absorption. Even with such a development, longitudinal displacement of the rod with respect to the heat radiation lamps, as well as twisting around the longitudinal axis of the rod, has no disadvantageous effects on the measurement result.
An advantageous embodiment of the invention also consists in that the zones are formed by applying metals of high heat reflection to one part of the rod surface. Due to this only partial coating, the already existing characteristic of the rod surface for high heat absorption is utilized for forming the appropriate absorbing zone. The metal can be applied by vapour deposition, electro-plating, screen printing or similar.
Finally, another advantageous embodiment of the invention is characterized in that, between the rod and the tube having a low thermal expansion, a cylindrical sleeve having high heat reflection is provided to form the heat reflection zone. Such a sleeve is simple to produce and can also be easily introduced into the tube, the movements of expansion of the rod advantageously remaining without influ ence on the sleeve.
In the text which follows, the invention is explained in greater detail with the aid of illustrative embodiments shown in the drawing, in which:
Figure 1 shows a diagrammatic cross-section through a heating element having a device according to the invention for controlling or limiting the temperature,
Figure 2 shows a top view of an enlarged device according to the invention according to
Fig. 1,
Figure 3 shows an enlarged side view of a rod according to the device according to Fig.
2,
Figure 4 shows a cross-section through another embodiment of the rod, and
Figure 5 shows another illustrative embodiment of a rod according to the invention.
Fig. 1 shows a radiation-type heating element 1 which consists of a pot 2 in which a heating zone is located which exists by virtue of a halogen lamp 3. This halogen lamp 3 is arranged below a plate 4 of metal, glass-ceramics or similar which forms a cooking surface 5. Between the cooking surface 5 and the halogen lamp 3, a temperature sensor 6 is arranged which is connected with a switching head 7' provided with the contact system, the temperature sensor 6 constructed as a device for controlling or limiting the temperature being carried in simple manner through a drilled hole of the radiation-type heating element 1.
In this manner, the temperature sensor 6 is exposed to the temperature prevailing below the cooking surface 5 in the heat radiation space between the cooking surface and the halogen lamp 3.
In Fig. 2, the device for controlling or limiting the temperature and provided with the temperature sensor 6 and the switching head 7' is shown in detail at an enlarged scale. The temperature sensor 6 is provided with a rod 7 of a highly temperature-resistant material having a high thermal coefficient of expansion, for example a nickel-chromium alloy or an Fe-Cr alloy which is arranged in a tube 8. The rod 7 has two zones 30, 31, of which the zone 31 is arranged at the free end of the rod 7 and is formed by the surface of the rod material having a high thermal coefficient of expansion (Fig. 3). The zone 30 adjoining the switching head 7' is formed by a layer 32 of metal with a high heat reflection, for example silver which is applied to the rod 7. This layer can be applied by vapour-deposition, by electroplating, by screen printing or similar.A large proportion of the radiation heat emitted by the halogen lamps 3 is reflected by this layer 32 and thus kept away from the rod 7. Only the radiation impinging on the front zone 31 of high heat absorption is absorbed and causes a corresponding expansion of the rod 7.
Tests involving a 17 cm long rod 7, in which the zone 31 of high heat absorption had a length of 4 cm, have produced a At, that is to say the temperature difference in which the contact 24, 26 is switched on and off respectively, of 30"C with only nine switching events in two minutes. In comparison with this, the switching rate was almost three times as high with a completely uncoated rod of the same length and using the same halogen lamps, but the At was less than 10 C. Although a completely silver-coated rod of the same length showed only a very low switching rate, a At of 100"C was found.
The tube 8 enclosing the rod 7 is formed, for example, from quartz. The ends of the tube 8 carry caps 11, 12, the cap 11 being supported against a base plate 13 which is screwed to the switching head 8 by means of screws 14. The rod 7 is carried through drilled holes in the cap 11, the base plate 13 and the cap 12 and has a thread 15 at its end located near the cap 12, a nut 16 being screwed onto this thread.
The other end of the rod 7 is provided with a dished collar 17. Between the collar 17 and the base plate 13, and thus between the collar 17 and one end of the tube 8 containing the rod 7, a compression spring 18 is arranged which keeps the rod 7 under tensile load and thus presses the nut 16 against the outside of the cap 12.
The rod 7, the tube 8, the two caps 11, 12, the nut 16, the base plate 13 and the compression spring 18 form the temperature sensor which is screwed to the switching head 7' by means of the screws 14, the switching head 7' being provided with a recess 19 into which the end of the rod 7 provided with the compression spring 18 is inserted.
The switching head 7' forms a housing 20 which is open towards the top, in which arrangement the open end can be covered by a cover plate. The inside of the housing 20 is connected to the recess 19 via a drill hole extending at least approximately axially with respect to the rod 7, in which hole a transfer element 22 is located which is axially displaceable in the drilled hole. One end of the transfer element 22 rests against the dished surface of the collar 17. The transfer element 22 has an actuating surface 23 for actuating the contact system which is used for controlling or limiting the temperature and which is provided with a contact spring 25 carrying the moving contact 24 and a connecting tab 27 provided with the fixed contact 26. The contact spring 25 is permanently connected to a spring support 28 which also carries the contact spring 25.
In the state shown in Fig. 2, the contacts 24, 26 are open and the heating circuit is thus interrupted. If a supply voltage is applied to the heating circuit, the halogen lamp 3 is heated, as a result of which the temperature rises in the space between the cooking sur face 5 and the halogen lamp 3. As a consequence, the rod 7 expands so that the transfer element 22 is moved towards the point of actuation of the contact spring 25.
As soon as the temperature of, for example, 700"C is reached in the space between the cooking surface 5 and the halogen lamp 3, the actuating surface 23 of the transfer element 22 presses against the contact spring 25, the contacts 24, 26 being suddenly separated so that the heating system is switched off. Since the rod 7 is shortened in the course of the subsequent cooling, the contact spring 25 snaps back into the position in which the contacts 24, 26 are closed.
The rod 7, shown in cross-section in Fig. 4, has zones 35 which are distributed over its circumference and which consist, for example, of deposited silver. These zones extend in the longitudinal direction of the rod over its entire length. Between these zones 35, zones 36 are located which are formed by the uncoated material of the rod 7. These forms are preferably constructed to be strip-shaped and alternate with each other, if necessary, in different sequence.
However, the zone of high heat reflection can also be annularly and/or helically arranged on the rod 7 having a high heat absorption.
The rod 7 according to Fig. 5 shown in longitudinal cross-section is partially covered by a cylindrical sleeve 37 which is arranged between the tube 8 and the rod 7. In this manner, the heat radiation is reflected by the sleeve 37 so that this also forms a zone of high heat reflection. This sleeve can be a metal foil, preferably a silver foil.
Claims (7)
1. Device for controlling or limiting the temperature of radiation- or contact-type heating elements of electric cooking appiiances comprising cooking surfaces consisting of metal, glass-ceramics or similar, in which device, between the heating element and the cooking surface, at least one temperature sensor is arranged which is provided with a rod having a high thermal expansion, which rod is provided with a layer which reflects heat radiation and is arranged in a tube having a low thermal expansion, one end of the rod being connected to a contact system used for regulating or limiting the temperature of the heating element, wherein the rod (7) is provided both with a zone (30), known in itself, of high heat reflection and with a zone (31) of high heat absorption.
2. Device according to Claim 1, characterized in that the zone (31) of high heat absorption is formed by the surface of the rod material.
3. Device according to Claim 1, characterized in that both zones (30, 31) are arranged to extend in the longitudinal direction of the rod (7) and are distributed over the rod circumference.
4. Device according to Claim 1 or 3, characterized in that the two zones (30, 31) are constructed in the shape of strips and, if necessary, are distributed in different sequence over the rod circumference.
5. Device according to Claim 1, characterized in that the zone (30) of high heat reflection is annularly and/or helically arranged on the rod (7) having a high heat absorption.
6. Device according to one of Claims 1 to 5, characterized in that the zone (30, 31) are formed by applying metals with high heat reflection to one part of the rod surface.
7. Device according to one of Claims 1 to 6, characterized in that a cylindrical sleeve (37) having a high heat reflection is provided between the rod (7) and the tube (8) having low thermal expansion, in order to form the heat reflection zone (30).
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT0058685A AT381784B (en) | 1985-02-27 | 1985-02-27 | DEVICE FOR REGULATING OR LIMITING THE TEMPERATURE OF RADIATION OR CONTACT HEATERS |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8604733D0 GB8604733D0 (en) | 1986-04-03 |
| GB2171795A true GB2171795A (en) | 1986-09-03 |
| GB2171795B GB2171795B (en) | 1989-06-21 |
Family
ID=3494508
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8604733A Expired GB2171795B (en) | 1985-02-27 | 1986-02-26 | Device for controlling or limiting the temperature of radiation- or contact-type heating elements |
Country Status (5)
| Country | Link |
|---|---|
| AT (1) | AT381784B (en) |
| DE (1) | DE3601634C2 (en) |
| FR (1) | FR2578031A1 (en) |
| GB (1) | GB2171795B (en) |
| IT (2) | IT1191370B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001072088A1 (en) * | 2000-03-23 | 2001-09-27 | Ceramaspeed Limited | Temperature sensor |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4002322A1 (en) * | 1990-01-26 | 1991-08-01 | Bosch Siemens Hausgeraete | COOKING AREA |
| DE4126790C2 (en) * | 1991-08-14 | 2002-06-06 | Miele & Cie | Process for producing an oven with an enamelled baking muffle |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE419806B (en) * | 1973-08-30 | 1981-08-24 | Ego Elektro Blanc & Fischer | ELECTRICAL SWITCH |
| DE7826549U1 (en) * | 1978-09-07 | 1978-12-14 | E.G.O. Elektro-Geraete Blanc U. Fischer, 7519 Oberderdingen | TEMPERATURE LIMITER FOR GAS-HEATED CERAMIC GLASS COOKING SURFACES |
| GB2069300B (en) * | 1980-02-01 | 1983-09-01 | Mictropore International Ltd | Radiant heating elements for smooth top cookers |
| GB2132060B (en) * | 1982-12-24 | 1985-12-18 | Thorn Emi Domestic Appliances | Heating apparatus |
| AT376540B (en) * | 1983-01-05 | 1984-11-26 | Electrovac | DEVICE FOR CONTROLLING OR LIMITATION OF AT LEAST ONE TEMPERATURE VALUE OR A TEMPERATURE RANGE OF RADIATION OR CONTACT HEATER FROM ELECTRICAL COOKING EQUIPMENT |
| DE3302489A1 (en) * | 1983-01-26 | 1984-07-26 | Ego Elektro Blanc & Fischer | ELECTRIC RADIATOR HEATER FOR HEATING COOKING OR WARM PLATES, ESPECIALLY GLASS CERAMIC PLATES |
| GB8324271D0 (en) * | 1983-09-10 | 1983-10-12 | Micropore International Ltd | Thermal cut-out device |
-
1985
- 1985-02-27 AT AT0058685A patent/AT381784B/en not_active IP Right Cessation
-
1986
- 1986-01-21 DE DE3601634A patent/DE3601634C2/en not_active Expired - Fee Related
- 1986-01-30 IT IT04802/86A patent/IT1191370B/en active
- 1986-01-30 IT IT1986A04802A patent/IT8604802A1/en unknown
- 1986-02-21 FR FR8602393A patent/FR2578031A1/en not_active Withdrawn
- 1986-02-26 GB GB8604733A patent/GB2171795B/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001072088A1 (en) * | 2000-03-23 | 2001-09-27 | Ceramaspeed Limited | Temperature sensor |
| US6752531B2 (en) | 2000-03-23 | 2004-06-22 | Ceramaspeed Limited | Temperature sensor |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3601634C2 (en) | 1996-07-11 |
| FR2578031A1 (en) | 1986-08-29 |
| AT381784B (en) | 1986-11-25 |
| IT1191370B (en) | 1988-03-23 |
| DE3601634A1 (en) | 1986-10-16 |
| GB8604733D0 (en) | 1986-04-03 |
| GB2171795B (en) | 1989-06-21 |
| IT8604802A1 (en) | 1987-07-30 |
| ATA58685A (en) | 1986-04-15 |
| IT8604802A0 (en) | 1986-01-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5270519A (en) | Radiant heater having multiple heating zones | |
| US5138135A (en) | Cooktop | |
| EP0176027B1 (en) | Radiative heating body for a cooking apparatus | |
| EP0164900B1 (en) | Heating apparatus | |
| EP0206597B1 (en) | Improvements in or relating to infra-red heaters | |
| US4267815A (en) | Thermal cut-out for gas-heated glass ceramic cooking surfaces | |
| US5310993A (en) | Device for controlling or limiting temperature in an electric cooking appliance | |
| US5049726A (en) | Radiant electric heaters | |
| US5919385A (en) | Cooking apparatus | |
| GB2171795A (en) | Device for controlling the temperature of heating elements | |
| US4892997A (en) | Electric heaters | |
| GB2339475A (en) | Temperature sensor for a cooking hob | |
| US3423572A (en) | Control for surface heaters | |
| GB2161348A (en) | Radiation heater reflector | |
| EP0174774A1 (en) | Heating apparatus | |
| US5892206A (en) | Radiant electric heater arrangement and method of operating the same | |
| US3375346A (en) | Infrared surface heating unit with two filaments | |
| EP0150087B1 (en) | A thermal limiting device | |
| FI91476C (en) | Temperature controlled hotplate | |
| US4631390A (en) | Thermal limiter | |
| JPS6171579A (en) | Heating device | |
| GB2225920A (en) | Controlling an electric heater unit for an electric ceramic hob | |
| CA1076652A (en) | Combination microwave/thermal oven thermostat | |
| JPH0648099B2 (en) | Electric stove | |
| GB2164150A (en) | Temperature responsive actuating elements |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PE20 | Patent expired after termination of 20 years |
Effective date: 20060225 |