GB2260442A - Temperature control devices for radiant heaters - Google Patents
Temperature control devices for radiant heaters Download PDFInfo
- Publication number
- GB2260442A GB2260442A GB9121369A GB9121369A GB2260442A GB 2260442 A GB2260442 A GB 2260442A GB 9121369 A GB9121369 A GB 9121369A GB 9121369 A GB9121369 A GB 9121369A GB 2260442 A GB2260442 A GB 2260442A
- Authority
- GB
- United Kingdom
- Prior art keywords
- radiant heater
- temperature sensor
- temperature control
- control device
- temperature
- 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
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
- H05B3/00—Ohmic-resistance heating
- H05B3/68—Heating arrangements specially adapted for cooking plates or analogous hot-plates
- H05B3/74—Non-metallic plates, e.g. vitroceramic, ceramic or glassceramic hobs, also including power or control circuits
- H05B3/748—Resistive heating elements, i.e. heating elements exposed to the air, e.g. coil wire heater
-
- 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
Abstract
A temperature control device for a radiant heater (1) for a cooker comprises a thermally responsive switch assembly (7, 8). The thermally responsive switch assembly comprises switch means (7) for mounting directly or indirectly on the radiant heater and an elongate thermally expansive temperature sensor (8) operatively connected at one end thereof to the switch means for extending across the radiant heater so as to be exposed to heat emitted by the heater. A mounting means (9) for mounting on the radiant heater includes means for securing the other end of the temperature sensor (8) such that the other end is fixed relative to the radiant heater. In use, as the temperature of the temperature sensor (8) rises the sensor expands relative to the radiant heater (1) so as to operate the switch means (7) at a predetermined temperature. <IMAGE>
Description
TEMPERATURE CONTROL DEVICE FOR A RADIANT HEATER
The present invention relates to a temperature control device for a radiant heater and may be used, for example, in conjunction with a radiant heater installed in a glass ceramic top cooker.
Temperature control devices are known in conjunction with radiant heaters installed in glass ceramic top cookers.
Such temperature control devices typically incorporate a rod-like temperature sensor that operates on the basis of a difference in thermal expansion coefficients between an expansion member of the sensor and a reference member of the sensor. The difference in thermal expansion gives rise to differential movement which, in turn, is employed to operate one or more switches which are used, for example to limit the temperature of the glass ceramic cooking surface and/or to warn that the surface of the glass ceramic is too hot to be touched. The temperature sensor generally comprises a rod of high expansion material located coaxially within a tube of low expansion material such as quartz. Alternatively, the temperature sensor may comprise an expansion tape or strip which is arranged at one side of a ceramic reference member.A rod-like temperature sensor in either of these forms has the disadvantage of vulnerability to damage of the reference member.
It is an object of the present invention to provide a temperature control device incorporating an elongate temperature sensor in which the reference member is less vulnerable to damage.
According to one aspect of the present invention there is provided a temperature control device for a radiant heater comprising: switch means for mounting directly or indirectly on the radiant heater; an elongate temperature sensor operatively connected at one end thereof to the switch means, for extending across the radiant heater so as to be exposed to heat emitted by the heater; and mounting means for mounting on the radiant heater, the mounting means including means for receiving the other end of the temperature sensor.
The switch means may be mounted on the mounting means which is adapted to be positioned externally of the radiant heater.
The temperature sensor may be in the form of a tape, wire or rod.
The mounting means may be provided with means for adjusting the position of the temperature sensor relative to the switch.
According to another aspect of the present invention there is provided a radiant heater for use in cooking apparatus including a temperature control device as hereinbefore defined.
According to a further aspect of the present invention there is provided cooking apparatus including a cooking plate and a radiant heater as hereinbefore defined.
The cooking plate may comprise glass ceramic.
For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which:
Figure 1 is a diagrammatic cross-sectional view of one embodiment of a temperature control device according to the present invention incorporated into a radiant heater for a glass ceramic top cooker; and
Figure 2 is a diagrammatic cross-sectional view of another embodiment of a temperature control device according to the present invention incorporated into a radiant heater for a glass ceramic top cooker.
Figure 1 shows one embodiment of the present invention in which a radiant heater 1 is arranged beneath a glass ceramic cooking plate 2. The radiant heater comprises a metal supporting dish 3 containing a base layer 4 of thermal and electrical insulating material and a peripheral wall 5 of thermal insulating material. Supported in grooves formed in the surface of the base layer 4 is a bare wire heating coil 6.
Switch means 7 is attached to one side of the supporting dish 3 and an elongate temperature sensor 8 is attached to the switch means 7. Switch means 7 may incorporate one or more switches, for example one switch set to operate in the region of a glass surface temperature of 550 OC in order to protect the glass ceramic cooking plate against excessive temperatures and another switch set to operate in the region of a glass surface temperature of 60 OC in order to provide an indication that the cooking plate may be too hot to touch. The temperature sensor 8 is also attached to that side of the supporting dish substantially diametrically opposite the switch means 7 by means of a mounting element 9. The temperature sensor extends above the heating coil 6 and is directly exposed to radiation emitted from the coil.
The switch means 7 is operated by means of differential expansion that arises as a result of the relatively low thermal expansion of the supporting dish 3, which is not exposed directly to heat emitted by the heating coil 6 and is therefore at a lower temperature than the temperature sensor 8 and which thus serves as a reference member, and the relatively high thermal expansion of the temperature sensor 8, which is directly exposed to heat emitted by the heating coil 6 and/or the glass ceramic cooking plate 2 and which thus serves as an expansion member.
The temperature sensor 8 may be in the form, for example, of a rod, a wire or a tape and may be rigid or flexible.
The temperature sensor may be made, for example, a high chrome steel having a relatively high coefficient of thermal expansion. It is also possible to introduce into the temperature sensor lengths of material having a lower coefficient of thermal expansion if it is desired to make certain portions of the temperature sensor less sensitive than others. A further possibility is to coat all or part of the temperature sensor with a reflective material. The temperature sensor 8 may be positioned to extend across the heater 1 in close proximity to, or in contact with, the underside of the glass ceramic plate 2.Alternatively, the temperature sensor may be spaced a predetermined distance from the underside of the glass ceramic plate as is the case with conventional rod-like temperature sensors with the possibility of the temperature sensor 8 being threaded through apertures conventionally provided in the supporting dish 3 and the peripheral wall 5.
In use of the temperature control device according to the present invention, the temperature at which the device is to operate is set subsequent to the switch means 7 and the temperature sensor 8 being mounted on the heater 1, for example by adjusting the position of the temperature sensor 8 relative to the switch 7 by way of the mounting element 9, in a manner well known to the skilled person, and subsequently locking the temperature sensor in position with respect to the mounting means 9 and thus the supporting dish 3.
The temperature control device according to the present invention has the advantage that, compared with conventional temperature control devices which incorporate rod-type temperature sensors, it is less likely to suffer permanent damage if it is subject to shock or contact with other components.
Figure 2 shows another embodiment of the present invention which is a modification of the embodiment shown in Figure 1. The same reference numerals are used in Figure 2 to denote the same or similar parts to those shown in Figure 1.
Figure 2 shows that the mounting means 9 extends beneath, and is secured to the underside of, the supporting dish 3 of the radiant heater 1 and that the switch means 7 is arranged on the mounting means 9 instead of being arranged directly on the supporting dish 3. Such an arrangement can offer greater thermal isolation of the reference member, in this case the mounting means 9, from the base of the supporting dish 3, leading to a greater differential expansion between the temperature sensor 8 which forms the expansion member and the mounting means 9 which forms the reference member. This leads in turn to greater sensitivity of the temperature control device.
The temperature at which the device as shown in Figure 2 is to operate may be set subsequent to the mounting means 9 being mounted on the heater 1 as with the embodiment of
Figure 1, or may be set prior to the mounting means being attached to the heater. The use of a separate reference member as part of the mounting means has the added advantage that the reference member may be compensated for expansion that may occur as a result of changes in ambient temperature, for example by the use of low expansion ceramic materials or the use of composite materials.
Claims (8)
1. A temperature control device for a radiant heater comprising: switch means for mounting directly or indirectly on the radiant heater; an elongate temperature sensor operatively connected at one end thereof to the switch means, for extending across the radiant heater so as to be exposed to heat emitted by the heater; and mounting means for mounting on the radiant heater, the mounting means including means for receiving the other end of the temperature sensor.
2. A temperature control device according to claim 1, wherein the switch means is mounted on the mounting means which is adapted to be positioned externally of the radiant heater.
3. A temperature control device according to claim 1 or 2, wherein the temperature sensor is in the form of a tape, wire or rod.
4. A temperature control device as claimed in any preceding claim, wherein the mounting means is provided with means for adjusting the position of the temperature sensor relative to the switch.
5. A temperature control device for a radiant heater substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.
6. A radiant heater for use in cooking apparatus including a temperature control device as claimed in any preceding claim.
7. Cooking apparatus including a cooking plate and a radiant heater as claimed in claim 6.
8. Cooking apparatus as claimed in claim 7, wherein the cooking plate comprises glass ceramic.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9121369A GB2260442B (en) | 1991-10-09 | 1991-10-09 | Radiant heater incorporating a temperature control device |
| DE9213388U DE9213388U1 (en) | 1991-10-09 | 1992-10-06 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9121369A GB2260442B (en) | 1991-10-09 | 1991-10-09 | Radiant heater incorporating a temperature control device |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9121369D0 GB9121369D0 (en) | 1991-11-20 |
| GB2260442A true GB2260442A (en) | 1993-04-14 |
| GB2260442B GB2260442B (en) | 1995-06-07 |
Family
ID=10702611
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9121369A Expired - Fee Related GB2260442B (en) | 1991-10-09 | 1991-10-09 | Radiant heater incorporating a temperature control device |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE9213388U1 (en) |
| GB (1) | GB2260442B (en) |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB856257A (en) * | 1957-08-09 | 1960-12-14 | William John Sims | Improvements relating to electrically heated irons |
| US4327280A (en) * | 1979-02-07 | 1982-04-27 | Micropore International Limited | Smooth top cookers |
| US4393299A (en) * | 1980-11-17 | 1983-07-12 | Micropore International Limited | Electric radiant heater unit for a glass ceramic top cooker |
| US4508961A (en) * | 1982-03-02 | 1985-04-02 | Micropore International Limited | Electric radiant heater units for glass ceramic top cookers |
| GB2181896A (en) * | 1985-10-17 | 1987-04-29 | Ako Werke Gmbh & Co | Circuit-breaker for protection of a radiant heating means against overheating |
| US4665307A (en) * | 1983-09-10 | 1987-05-12 | Micropore International Limited | Thermal cut-out device for radiant heaters |
| US4845340A (en) * | 1987-05-01 | 1989-07-04 | E.G.O. Elektro-Gerate Blanc U. Fischer | Electric radiant heating element for heating a plate particularly a glass ceramic plate |
| GB2225920A (en) * | 1988-12-09 | 1990-06-13 | Redring Electric Ltd | Controlling an electric heater unit for an electric ceramic hob |
-
1991
- 1991-10-09 GB GB9121369A patent/GB2260442B/en not_active Expired - Fee Related
-
1992
- 1992-10-06 DE DE9213388U patent/DE9213388U1/de not_active Expired - Lifetime
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB856257A (en) * | 1957-08-09 | 1960-12-14 | William John Sims | Improvements relating to electrically heated irons |
| US4327280A (en) * | 1979-02-07 | 1982-04-27 | Micropore International Limited | Smooth top cookers |
| US4393299A (en) * | 1980-11-17 | 1983-07-12 | Micropore International Limited | Electric radiant heater unit for a glass ceramic top cooker |
| US4508961A (en) * | 1982-03-02 | 1985-04-02 | Micropore International Limited | Electric radiant heater units for glass ceramic top cookers |
| US4665307A (en) * | 1983-09-10 | 1987-05-12 | Micropore International Limited | Thermal cut-out device for radiant heaters |
| GB2181896A (en) * | 1985-10-17 | 1987-04-29 | Ako Werke Gmbh & Co | Circuit-breaker for protection of a radiant heating means against overheating |
| US4845340A (en) * | 1987-05-01 | 1989-07-04 | E.G.O. Elektro-Gerate Blanc U. Fischer | Electric radiant heating element for heating a plate particularly a glass ceramic plate |
| GB2225920A (en) * | 1988-12-09 | 1990-06-13 | Redring Electric Ltd | Controlling an electric heater unit for an electric ceramic hob |
Also Published As
| Publication number | Publication date |
|---|---|
| DE9213388U1 (en) | 1992-12-03 |
| GB2260442B (en) | 1995-06-07 |
| GB9121369D0 (en) | 1991-11-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20061009 |